The commensurability condition is applied to determine the hierarchy of fractional fillings of Landau levels in monolayer and in bilayer graphene. The filling rates for fractional quantum Hall effect (FQHE) in graphene are found in the first three Landau levels in one-to-one agreement with the experimental data. The presence of even denominator filling fractions in the hierarchy for FQHE in bilayer graphene is explained. Experimentally observed hierarchy of FQHE in the first and second Landau levels in monolayer graphene and in the zeroth Landau level in bilayer graphene is beyond the conventional composite fermion interpretation but fits to the presented nonlocal topology commensurability condition.  SU(4) spin-valley symmetry is broken by a larger magnetic field, the new features for IQHE appear, corresponding to removal of LL subbands degeneracy [Recent progress in Hall experiments with graphene has revealed many new features in longitudinal and transversal resistivity in Hall configurations characteristic for fractional quantum Hall effect (FQHE), both in suspended graphene scrapings –3, and igeneracy . In the graphene . EspeciaIn the present paper we analyze the hierarchy for fractional fillings linked to strongly correlated multiparticle states in graphene using the topological commensurability approach developed earlier for the ordinary 2DEG Hall systems –10. In t2. N-fold normal product of the manifold N elements [N particle system resulting in special shapes of trajectories are not important here, unless they cause the topological nonequivalence. Only topology of trajectories on M decides whether one trajectory loop can be continuously transformed into another one without a cut or not. If a smooth continuous transformation is impossible between two trajectories, they are topologically nonequivalent and fall into distinct classes of the full braid group. Thus, the full braid group does not reflect the dynamics details, but rather identifies the topology restrictions imposed on the multiparticle system, which are associated to some global features of the system including the manifold type and only those aspects of interaction that might cause topological nonequivalence of trajectories. The Coulomb repulsion of electrons on the plane is a central prerequisite for the braid group definition at magnetic field presence, because the scale of interparticle separation defined by the Coulomb repulsion must interfere with the planar cyclotron orbits, discriminating in this way possible correlation types. As the loops from i-th particle on the manifold M, i.e., the classical position of the i-th particle on M) are changing along a selected loop from the The concept of the commensurability of cyclotron trajectories with interparticle spacing in a 2D charged system at strong magnetic field is born in relation to the braid group approach to multiparticle systems in the presence of a magnetic field, and employs the interaction of electrons, essential for formation of any correlated state, including states corresponding to FQHE. The collective behavior of a quantum multiparticle state must be assigned by the statistics phase shift acquired by the multiparticle wave function if one considers position exchanges of particle pairs ,13. The elements . The quoar braid . In thisnt 1DURs :(1) σi→ei-th and M the braid groups differ considerably from the permutation group. For where he 1DURs :(2) σi→ecorresponding to so-called anyons . This is illustrated in the central panel of Figure BA must be shared among three loops with the same surface A (i.e. BA for each loop). Thus, each loop accommodated to the flux quantum A and gives the contribution BA to the flux, resulting in the total flux 3BA per particle, as needed – this is schematically illustrated in Figure A in the right panel is equal to A in the left panel, which means that the three-loop orbits fit to the interparticle separation.In Figure As the braid group generator must be defined by the half of the cyclotron orbit . The genductors .x-th particle separation  is here 4. This corresponds to the ordinary Zeeman spin-splitting and to the so-called valley splitting (expressed often in terms of a pseudospin) due to doublet of inequivalent K points mixed with two sublattices for C atoms in crystal lattice of graphene [In graphene one deals with the relativistic version of LLs ,23. Thisnds meet . Thus thgraphene  and the rvations . The remThe Berry phase contribution is linked to an additional Similar analysis of the LLs can be done for the bilayer graphene ,24. Due  and n=1 ,24. Beca the LLs ,24.3.1. For the magnetic field strong enough that The cyclotron orbits in the LLL must be accommodated to the bare kinetic energy S is the sample surface). As this orbit size is lower than the interparticle separation l-th particles. In this way one can obtain the hierarchy of fillings for FQHE in this subband of the LLL, q-looped orbit x-th particle . For hoFor the completely filled subband x-th particle) we get Similarly one can consider fillings of the following LL with At the special case q-looped orbits, their size may be accommodated to every x-th particle in the subband, resulting in additional hierarchy in all subbands of the first LL, Moreover, for , ν=23,4,+xll3(q-1n), whereas the interparticle distances are measured with the plaque The following subbands are filled with electrons upon the similar scheme. For the subband 3.2. The special topology of the bilayer graphene creates the opportunity to verify the braid group based concept of the commensurability of cyclotron orbit size with the interparticle spacing in the planar system of interacting particles. Let us emphasize once more that the interaction is essential for correlation manifestation – the interaction prevents particles from approaching one another closer than the particle separation resulting from the planar density. This separation is rigidly kept by the interaction allowing the commensurability notion to be useful. Exclusively when the cyclotron orbits fit accurately to the particle spacing the exchange of neighboring particles in the presence of the perpendicular magnetic field is possible along specific braids named as the cyclotron braids.It must be emphasized that commensurability condition, as related to the braid group, concerns the classical archetype of the quantum system, thus is not addressed to real quantum particles which do not have any trajectories. This agrees with the spirit of the braid group approach in which classical trajectories in configuration space supply information on quantum statistics via 1DURs of the braid group. To organize any correlated collective state, the related statistics of particles must be determined first. In order to establish the statistics of quantum particles, the appropriate braid group must be defined whereas the statistics is governed by the selected 1DUR of this group .The bilayer graphene is, however, not strictly two dimensional and for the bilayer graphene the topological situation changes considerably. Two sheets of the graphene plane lie close to each other and the hopping can change the electron positions among the planes. Thus, we deal here with double the number of electrons residing on a two-sheet structure simultaneously instead of the single sheet as was the case for the monolayer graphene.doublelooped cyclotron orbits may have in bilayer graphene the same size as the single-looped orbit in opposition to the monolayer case. This follows from the fact that the second loop can be located in the opposite sheet of graphene than the first one and the external field passing through such doublelooped orbit is twice larger than the flux passing through the single-looped orbit. Each loop has in this case its own separate surface in contrary to the multilooped cyclotron orbit located on the purely 2D plane. Taking into account that in the bilayer system loops of the multilooped orbit may be located partly in both 2D sheets, the contribution of the one loop must be avoided whereas the remaining loops must share the same flux as passing through a single-looped orbit, independently of how loops are distributed among two sheets. Thus, one can write out the commensurability condition in the bilayer graphene for the case of too short single-looped cyclotron orbits in the following form , and p is an odd integer to assure that the half of the cyclotron orbit defines the braid.where, p-looped cyclotron orbit take part only The factor Equation  is causep – thus the generators of the corresponding cyclotron subgroup are of the form p exponent for the Jastrow polynomial. But due to the distinct commensurability of orbits with interparticle separation (Equation (p-odd) in the first particle-type subband of the LLL, i.e., in the subband Let us emphasize that for such multilooped orbits the total number of loops is still Equation ) the reln due to the same size of the cyclotron orbits.For holes in this subband  one can write Some novelty occurs, however, in the following two subbands of the LLL, The generalization of this main series for holes in the subband and to the full FQHE hierarchy in this subband is as follows: for subband holes, In the subband The last subband The evolution of the fractional filling hierarchy of subsequent LLs is illustrated in Figures For bilayer graphene the degeneration of One can consider also the situation in the LLL of bilayer graphene, when the degeneracy of ∗<1 , it wasce band) ,29. Both011 cm-2 ; and in FQHE in suspended graphene is observed at relatively high temperatures around 10 K , and eveThe competition between the FQHE state with the insulator state near the Dirac point, corresponding to a rapidly decreasing concentration has also been demonstrated ,33 Figu.From the perspective of cyclotron groups, experimental results on FQHE in graphene –31,34 se5-60 V ) allows 5-60 V ,29. For 5-60 V . In the 5-60 V  may exhiBN) in high magnetic fields of the order of 40 T  .The mobility of carriers in graphene is lower than in traditional 2DEG, but taking into account that the carrier concentration in graphene can be lower in comparison to semiconductor heterostructure ,38, the Energy gaps protecting incompressible FQHE states are larger in graphene than in traditional semiconductor materials, reaching a magnitude in order of 16 K  , the subn. The repeating doublet of filling ratios for If one compares the experimentally observed fractions for characteristic FQHE features in longitudinal and Hall conductivities measured on a variety of samples of graphene with the pattern of fractional hierarchy for two lowest LLs, as illustrated in Figure le-loop) –5. The n3), 133,13, , 3,113, -rates indistinguishable at the observation resolution. In higher LL the new features, however, occur in between the above-mentioned doublets, but with nonzero longitudinal resistivity contrary to other FQHE states. This suggests that not all particles participate in these correlated states and they may correspond to the multilooped correlations of every second or every third particles according the appropriate cyclotron commensurability. And indeed these new features in the first LL of monolayer graphene, recently reported  at ν=73,N, B)-plane in Figure N, B)-plane. Straight lines, which lie in a -plane and have a common point in a coordinate origin, are connected to a constant filling factor value; N, B)-plane can be described as n enumerating LL, b depending on n and LL degeneracy, first n and compressed to smaller periods for higher n, which also agrees with the details of the observation [Another experimental evidence for the above hierarchy follows from the measurement  of the tervation . SimilarThe most convincing evidence supporting the correctness of the commensurability condition is, however, the coincidence of the related predictions with the experimental observations in bilayer graphene. The pronounced feature of these observations is the occurrence of primary fractional features with even denominators also in the lowest subband of the LLL in bilayer graphene, oppositely to monolayer one . The comNote finally that the FQHE hierarchy in bilayer systems with the characteristic even denominators holds also for bilayer 2DEG conventional Hall setups and indeed the ed there ,41, whic5. The condition for commensurability of cyclotron orbits building cyclotron braid subgroups with interparticle spacing in homogeneous 2D charged systems is formulated in order to verify possibility of arrangement of correlated multiparticle Hall states. Using this commensurability condition based on the braid group approach to statistics of interacting many particle systems, the hierarchy of fractional fillings for LLs in graphene has been determined. The FQHE evolutionwith growing numbers of LLs has been described. In higher LLs the new opportunities for commensurability occur leading to the different than the ordinary FQHE(multiloop) correlated states. The fractional fillings of LLs related with this new commensurability opportunity have been identified, starting from the first LL. They are referred to FQHE(single-loop) because the related correlations are described by single-looped braids. Both the monolayer and bilayer graphene have been considered and the essential difference of related hierarchy structures has been demonstrated and described. The even denominator main line of the fractional filling hierarchy in bilayer graphene is found in agreement with the experimental observations. The confirmation of the presented hierarchy for the monolayer and bilayer graphene can be found in experimental data for both, the graphene on BN substrate as well as the suspended samples including bilayer graphene available for fillings up to sixth spin-valley subband.The success in description of hierarchy for FQHE using commensurability conditions is linked with the nonlocal and topological character of this approach. It is known that FQHE results from non-perturbative effects of the Coulomb interaction in 2D, which give rise to gapped many-body states at special filling factors. These states have long-range entanglement and cannot be explained in a simple single-particle picture. Similarly, the composite fermion theory, effective in the LLL of conventional 2DEG and in monolayer graphene, is in fact not strictly local, utilizing the auxiliary concept of flux tubes, or vortices, fixed to particles and allowing via this multiparticle effective trick to discriminate highly nonlocal effects. The commensurability approach presented in this paper bases on the topological braid group description of statistics in many body systems and falls to the same class of nonlocal multiparticle models. It elucidates artificial assumptions of composite fermion theory and allows for the generalization of the topological approach beyond the limit of the composite fermion model. In particular, the commensurability approach is effective also in higher LLs and allows the hierarchy of FQHE to be defined quite differently than that in the LLL – in agreement with experimental observations. Utilizing the energy minimization methods , the difference between FQHE states belonging to various Landau levels is referred to the different form of the effective Coulomb interaction (i.e. Coulomb interaction dressed by the form factor corresponding to a given Landau level). The energy minimization gives energy gaps for fractions related to special multiparticle correlations of FQHE. These fractions (and their hierarchy) can be, however, identified by a nonlocal effective-multiparticle topological method of commensurability braid approach, generalizing in this way the previous composite fermion approach from the LLL. The advantage of the commensurability condition is especially clearly visible in the case of bilayer graphene, where the states at fractions with even denominators cannot be explained by the simple composite fermion model, even in the LLL.


Botaurus stellaris among other 19 cohabiting birds species in The Parc Natural dels Aiguamolls de l’Empordà, showing an averaged recognition accuracy of 91% over 2h 55’ of representative data. The FPGA-based feature extraction implementation allows the system to process data from 30 acoustic sensors in real time with an affordable cost. Finally, several open questions derived from this research are discussed to be considered for future works.Fast environmental variations due to climate change can cause mass decline or even extinctions of species, having a dramatic impact on the future of biodiversity. During the last decade, different approaches have been proposed to track and monitor endangered species, generally based on costly semi-automatic systems that require human supervision adding limitations in coverage and time. However, the recent emergence of Wireless Acoustic Sensor Networks (WASN) has allowed non-intrusive remote monitoring of endangered species in real time through the automatic identification of the sound they emit. In this work, an FPGA-based WASN centralized architecture is proposed and validated on a simulated operation environment. The feasibility of the architecture is evaluated in a case study designed to detect the threatened  Biodiversity describes the full range of different varieties of life on Earth and their diversity. It is a measure a measure of the number and variability of organisms present in different ecosystems. Nevertheless, especially due to climate change, fast environmental changes can cause mass decline or even extinctions of species . The divThe bioacoustic study of specific species and locations may become a useful tool to evaluate the effect of climate change and habitats modification ,4. In thSpecifically, some bird species have suffered a dramatic reduction of breeding herds in the last decades in the majority of European countries, mainly due to the decrease of the quality and the availability of suitable habitats. They have been catalogued with a high level of protection at community sites by the European Directive 79/409/EEC . In ordeWhen it comes to designing a WASN-based birdsong recognition system to detect the presence of endangered species, two main approaches can be followed. In In the literature, different real-time signal processing platforms can be found, such as Graphics Processing Units (GPUs) ,14, commBotaurus stellaris songs within a simulated acoustic environment, which includes 19 other bird species cohabiting at The Parc Natural dels Aiguamolls de l’Empordà  [The aim of this work is to design and evaluate the feasibility of an FPGA-based centralized WASN architecture, which includes several acoustic sensors for the remote monitoring of endangered species in real time through the automatic identification of the birdsong in their natural habitat. We validate the architecture by developing a birdsong recognition system in a case study designed to detect the , Spain) . Despite, Spain) . FinallyBotaurus stellaris are found in This paper is structured as follows. The related work about birdsong recognition, reviewing different FPGA applications in the field of signal processing and the use of WASN, is detailed in In this section, we revise the main studies performed in automatic birdsong recognition and detail other signal processing applications implemented in real-time over an FPGA. We pay special attention to animal sound recognition and how WASNs have been used as a solution for wildlife monitoring.In the literature, we can find several biological projects focused on the acoustic detection of bird songs. The acoustic song recognition is suitable for the monitoring of bird species because many birds are better detected by sound than by vision . In thisIn , the perIn , each biIn , the detk-means classifier. Up to twelve different feature extraction coefficients are used to classify four different large databases of bird vocalizations  by means of random forest. The good performance of the unsupervised approach relies on the database possibilities to train the classification algorithm using only observed data [In , the autved data .In , an HHM-Several approaches to real-time automatic bird recognition can be found in the literature, using hardware platforms covering from microprocessors up to GPUs.Botaurus stellaris we are facing in this work, but the proposal does not ensure real-time performance in the sensor. In [k-means to classify the log-scaled Mel-spectrogram representation of each audio clip [In , a Raspbnsor. In , a protodio clip , which odio clip . ROBIN wdio clip ) with a In , the autThe use of microprocessors, as the aforementioned Raspberry Pi or any other Advanced RISC Machines (ARM) core embedded hardware platforms, present enough potential to address the signal processing and machine learning associated with birdsong classification computational load. However, due to the architecture of the microprocessor, the real-time requirements cannot be guaranteed despite the efficiency of the implemented algorithms. On the other hand, if a GPU hardware is used for single sensor acoustic birdsong detection, most of the approximations are over-dimensioned to achieve real-time performance. Despite its performance as a high computing device, it has high power consumption, which is a clear drawback to work in the wildlife.Three common FPGA signal processing fields of application are speech, music and communications . All of In , the autFinally, in , an FPGAWireless Acoustic Sensor Networks have multiple applications, such as surveillance in urban areas, ambient assisted living, environmental or wildlife monitoring .To our knowledge, the first WASN implemented for wildlife monitoring goes back to , which wIn , a WASN Finally, it is worth noting that most of the applications found in the literature apply the signal processing algorithms over the raw data in each node of the network as they are based on a distributed architecture, which increases the total cost of the network design.We present a WASN system following a centralized architecture paradigm based on a Zynq device . This centralized architecture, where the data processing takes place in a single device, allows us to implement simpler nodes than those presented in the related work, where a microprocessor or a FPGA are used in every single node to perform the signal processing. This simplification in the nodes reduces their costs and power consumption, which are the main constraints in WASNs deployed in the wild.a) simple nodes or motes, which are in charge of sensing the environment sounds and sending the raw data through wireless communication to the gateway, (b) the gateway, which is a subsystem able to coordinate the wireless network and collect all the raw data from the nodes re-transmitting them to the centralized recognition system, and (c) the recognition system, which provides the machine hearing functionality through the application of audio input feature extraction and machine learning. Moreover, a database to store the results of the analysis can be used remotely or included it in the recognition system platform.The proposed architecture to design an FPGA-based centralized WASN is depicted in The proposed hardware platform is based on a System on Chip (SoC) built on a Zynq FPGA. This kind of platform offers the possibility to implement algorithms of high computational cost in the programmable logic (PL) of the FPGA, which is a suitable solution when execution time is an important constraint. With such platform, while the FPGA implements the algorithms, the processing system (PS) of the ARM would implement an operating system to control the applications and the systems peripherals easily.Currently, Zynq devices allow high granularity between the low cost and the high performance fabric, as we can see in The FPGA contains the aforementioned bird recognition algorithm encapsulated as a whole intellectual property (IP) with Advanced Micro-controller Bus Architecture (AMBA) Advanced eXtensible Interface (AXI4) interface to communicate with an ARM microprocessor, which will be responsible for the control of the FPGA and which will include the machine learning classifier as well. AXI4 buses were adopted by Xilinx and are widely used to easily connect IPs with embedded micro-controllers or ARM cortex-A microprocessors such as MicroBlaze or Zynq, respectively, with several peripherals . Figure As stated before, the interfaces of this IP are based on AXI4 buses, which allow for establishing handshake between modules to read and write information with the aim of avoiding information loss due to low capacity buffers in some components. Both input and output interfaces have an asynchronous First Input First Output (FIFO) memory, using on one side the IP system clock and on the other side the ARM clock, since those might be the same speed or not, and might be synchronous with each other or not. This commonly used technique allows not only two clock domains running at different speeds (which is very common in SoCs), but also minimizes data loss and makes the system more agile since the FIFO can save as many data words from the fast clock as its depth.Botaurus stellaris birdsong among cohabiting species in a simulated environment. This is a key step before deploying an FPGA-based WASN designed to detect this species in protected places where their presence for reproduction is unknown nowadays. The common bittern (Botaurus stellaris), whose loud booming call performed by males during the breeding season can be heard from up to 2 km away [In order to validate the proposed system architecture, we develop a case study focused on the detection of  km away ,50, is n km away .The acoustic birdsong recognition algorithm implemented by the WASN consists of two different stages, as detailed in We select MFCC  as the fBotaurus stellaris and 19 coexisting bird species in The Parc Natural dels Aiguamolls de l’Empordà. The dataset lasts 8 h and 18 min approximately, with 30 recording files per species collected from the Xeno-Canto project [The dataset used to train and test the developed system includes the  project  sampled Botaurus stellaris is mainly characterized by its center frequency around 150 Hz, which can be detected thanks to the energy peaks in the suitable frequency band in low noise conditions [Botaurus stellaris call, while Ciconia ciconia, Motacilla flava and Porphyrio porphyrio, respectively. These spectrograms reveal notable acoustic and spectral differences between those species, as the bittern presents a narrow-band signal centered at very low frequencies, whilst Ciconia ciconia, Motacilla flava and Porphyrio porphyrio calls cover a wider spectrum at different higher frequencies up to 15 kHz, as it can be observed in The call of the nditions . Figure The process followed to compute MFCC is shown in The proposed implementation of the MFCC algorithm in the FPGA described in From In The audio birdsong recognition module aims to label automatically the correct species by means of the characterized MFCC corresponding to the 30 ms audio frames. For this purpose, this algorithm takes as an input the aforementioned 13-dimension vector from the feature extraction module obtaining as output the inferred label of the recognized species, considering an automatic classifier with supervised learning.n different sets of MFCC vectors corresponding to the n classes or species that we aim to classify. The k-means algorithm, which is an unsupervised learning algorithm, performs the estimation of the mean of every cluster for the n classes, which are modeled as a combination of different clusters of data. Subsequently, the mean of every cluster and the total number of clusters are fed the GMM fitting algorithm with the aim to approximate the cloud of data with a combination of multivariate Gaussians. We have conducted a comparative study considering a sweep of the number of mixtures. As you can see from n GMM models, the test data set is processed calculating the highest probability density for the n GMM inferring the class label for these audio frames.The supervised machine learning algorithm used is based on a GMM-approach  using sperved in . Finallyn models based on M multivariate Gaussian Distributions of dimension d for every model to obtain the class with the highest probability. The probability of every model M Gaussian distributions and a weights function The aforementioned GMM for multi-class supervised classification uses Equation . The comEquation , where Σd. The first part of Equation  the power consumption and (b) the cost of the nodes can be lower because each can be implemented with a single micro-controller instead of applying the signal processing algorithm over the raw data in each node using a microprocessor or FPGAs that has been implemented previously in a distributed architecture in the literature, due to the fact that the digital signal processing can be computed in the embedded platform. This reduction in the power consumption, which means an increase of the battery life and in the total cost, are one of the main constraints in WASN deployed in the wild.Future work should focus on the study and comparison of the different available wireless technologies with the aim to increase the battery life. Moreover, some techniques based on the sound event detection can be implemented to choose which audio frames should be transmitted or not to the centralized platform to reduce the transmission time. Despite the fact that it would reduce the power consumption of the system, it can only be applied if the micro-controller is able to assume the computational cost of the algorithm.Finally, the coverage area of the whole system depends on microphone directivity, wireless technology coverage and the maximum number of nodes gathered by the WASN.Based on our preliminary implementation, we propose a set of low cost platforms suitable to be used in the deployment of the whole system in the future. Some of them are listed in The presented birdsong recognition system is made up of a feature extraction which has been developed on the PL side of the Zynq, and a machine learning classifier which has been developed in the PS side. With the resources required in the feature extraction implementation on the PL side, which is detailed in Finally, if the number of sensors to monitor was smaller than 30, the frequency clock of the system could be lower than the proposed 100 MHz to drastically reduce the power consumption because the dissipation is a function of the system frequency . The finBotaurus stellaris recognition accuracies are placed among the best ones. Despite MFCC presenting good results for the classification conducted in this paper, other feature extraction techniques could be considered in the future, especially those specifically designed to represent music and songs [As a case study, the developed bird song recognition system shows good results when tested in a simulated environment over Matlab. In particular, the nd songs .This work has been conducted considering a typical configuration using MFCC and GMM and a synthetic dataset, with the aim to validate the whole proposal, leaving for future works its optimization. Although we have validated that working with 32 mixtures allows a good trade-off between recognition accuracy and computational cost, it is worth mentioning that, in our experience in similar investigations ,59, we hBotaurus stellaris song, a spectro-temporal analysis would likely improve the classification results because the temporal information in terms of repetitiveness, combined with the spectral occupation (closer to lower frequencies than nearly any other species), could improve the separability of our target endangered species.For instance, in the feature extraction stage, not only the spectral information could be taken into account, but also the temporal information . Due to Botaurus stellaris among coexisting bird species before moving the automatic recognition system from the simulated to the real-life environment. For that purpose, the authors consider that one of the potential next steps should compare the GMM performance to other machine learning algorithms. Multiple stage machine learning algorithms such as HMM [Gaussian Mixture Models have good overall performance in the tests conducted in this paper; despite this fact, there is some room for improving the robustness of the system to identify of the h as HMM ,22 can bAccording to several authors, Deep Neural Networks show good performance in automatic birdsong recognition, improving classical machine learning methods substantially when enough training data is available. In , the tecn-classification problem  when identified among the remaining 19 cohabiting bird species’ songs.The aforementioned proposal has been validated through a case study designed to detect the This work has also detailed the MFCC implementation on an FPGA device using a Zynq platform in which an ARM cortex-A and an FPGA coexist. Finally, an analysis of low cost Zynq platforms is done based on the required resources of the proposed MFCC plus GMM algorithm, concluding that up to 30 acoustic sensors can be processed in real time within the same FPGA as the upper bound of the WASN centralized architecture.In terms of the implementation of the birdsong recognition system, we have observed that the Mel scale filter bank entails the highest execution cost. Since the series implementation still shows acceptable results in terms of time consumption , we have opted for this implementation focusing on the reduction of the consumed resources (DSPs and LUTs) instead of minimizing the execution time . This is possible due to the low throughput of the input data. However, some extra optimization can be addressed in the future by increasing the degree of parallelization as well as choosing a more intensive architecture implementation in the FFT IP core. Both approaches would allow for processing hundreds of sensors at the cost of increasing the amount of computational resources required . These low-level adjustments should be performed depending on the optimization required by the specific application, the most important parameters being the number of sensors, the latency and execution time, and the computational resources and the power consumption.After this research focusing on the validation of the FPGA-based WASN architecture by means of a specific case study, we plan to design and develop a complete WASN-based system composed of several low-power microphones integrating the communication infrastructure in a real-life environment. These devices should have very low power consumption in order to extend lifespan of their powering batteries. Their main function will be to gather the acoustic data and send it to the centralized module through the gateway, namely, the aforementioned Zynq FPGA of Xilinx . Nevertheless, the specific requirements and design for the whole system  should be studied in detail before its implementation in future works. Moreover, the specific study about the geographic area coverage of the designed and validated WASN architecture in The Parc Natural dels Aiguamolls de l’Empordà is left for future works.Botaurus stellaris songs, which remains as an open question at the current stage of our research, since it is a species in severe recession in that natural park.Finally, it is worth noting that this work has been done in a simulated environement using a synthetic database. Therefore, a complete data set collected from The Parc Natural dels Aiguamolls de l’Empordà should be obtained and annotated accurately to evaluate the implemented system in real-life conditions with the same device characteristics. To that effect, a recording campaign should be conducted during several days/weeks in different places of the park in order to obtain enough representative environmental sounds and birdsongs in an open field. Nevertheless, one of the key issues of the recordings will be related to the collection of


The objective of this paper is to propose a novel tubular linear machine with hybrid permanent magnet arrays and multiple movers, which could be employed for either actuation or sensing technology. The hybrid magnet array produces flux distribution on both sides of windings, and thus helps to increase the signal strength in the windings. The multiple movers are important for airspace technology, because they can improve the system’s redundancy and reliability. The proposed design concept is presented, and the governing equations are obtained based on source free property and Maxwell equations. The magnetic field distribution in the linear machine is thus analytically formulated by using Bessel functions and harmonic expansion of magnetization vector. Numerical simulation is then conducted to validate the analytical solutions of the magnetic flux field. It is proved that the analytical model agrees with the numerical results well. Therefore, it can be utilized for the formulation of signal or force output subsequently, depending on its particular implementation. Linear machine generates translations directly without rotation-to-transmission conversion mechanisms, and thus achieves compact structure, high efficiency and good dynamic performance. It has wide applications in aerospace industries ,2, transMagnetic flux density is extremely important for the design of linear machines. High flux density helps to increase force output or signal strength depending on particular tasks. The conventional method is to increase the magnet size and thus the flux density. However, the large size or mass of the system is apparently not preferred for most applications, especially in aerospace technology. Alternatively, various magnet patterns have been proposed by researchers to enhance the magnetic flux density inside the linear machines without changing the system size significantly. Buren et al.  presentsThe objective of this study is to propose one novel linear permanent magnet machine with three-layer hybrid magnets and two-layer windings. The employment of the proposed structure offers the following advantages. The combination of conventional Halbach array and alternatively magnetized radial poles helps to enhance the magnetic flux density in the radial direction, and thus increase the force output of the linear machine. In addition, the utilization of multiple movers in the linear machine increases the redundancy and reliability of the system, which is extremely important for the aerospace technology. Furthermore, the winding mass is reduced, and thus the dynamic response could be improved significantly for moving coil designs. The design concept is presented, Laplace’s and Poisson’s equations are obtained from source free property of magnetic field and Maxwell equations. The general solution of magnetic vector potential is represented with Bessel functions. The flux distribution inside the machine is then formulated analytically by utilizing harmonic expansion of magnetization vectors and boundary conditions. Numerical computation is conducted to validate the analytical model and on the proposed design.The schematic structure of the proposed tubular linear machine is illustrated in In this section, the flux field in the proposed linear machine is formulated analytically. The obtained mathematical model could be employed for subsequent design optimization, modeling of thrust or output current, and high precision motion control.(a)z.The machine has a periodic magnetic structure along axial direction (b)The axial length is infinite, and thus the end effects can be ignored.(c)The distribution of magnetic field is axially symmetric.(d)The magnetic permeability of back iron is infinite.B(T) for these two regionsB is equal to the curl of magnetic vector potential, i.e.,To formulate the magnetic field mathematically, the space in linear machine under study is divided into two regions based on their magnetic characteristics. The air space is denoted as Region I. The PM pole filled with rare-earth magnetic material is denoted as Region II . AccordiThe Coulomb gauge is used as a constraint to uniquely determine the divergence of a vector. As a result, we have Laplace’s Equation, or governing equation for region IBased on the symmetric distribution of flux density in tubular linear machines, the Laplace’s equation, i.e., Equation (3) in cylindrical coordinates can be expanded and simplified asr and z, it can be represented with separation principle of variables asSince z axial, thus, the solution to magnetic potential in Region I isn is a positive integer.Substituting Equation (6) into (5) givesond kind , mn= is the same as Equation (8) and the particular part unctions . Therefoi = 1, 2, represents two sections of air region, while j = 1, 2, 3 represents internal, middle and external PMs respectively.From Equations (1), (8) and (15), the general solution of flux density is obtainedThere are 10 unknown coefficients in the analytical model of flux density, i.e., The major structural parameters in the boundary conditions are presented in Substituting Equations (16)–(18), (19) and (21) into Equation (20) will derive ten expanded equations describing ten boundary conditions respectively. They are shown as follows:The matrix form of Equations (22a) until (22j) isThe numerical approach is an effective way to analyze the magnetic flux field distribution of electromagnetic actuators. The values of major parameters for numerical computation are listed in The structure of the proposed linear machine is axially symmetric, so Magnetostatic 2D solver is conducted on Maxwell to model and analyze the flux field. In this study, the whole model is divided into 179,958 mesh elements to derive accurate solution, with the RMS edge length ranging from 0.00012 mm to 0.00051 mm for different parts of solving regions. The relationship between the number of iterative solving rounds and the energy error percentage is shown in Flux distribution corresponding to the initial and maximum working positions of coils without and with load is shown in To precisely observe the variation of magnetic flux field, The analytical model is a powerful tool for design optimization and control implementation of electromagnetic actuators. In contrast, the numerical approach is an efficient and reliable way to validate analytical results. To compare the numerical result and analytical model precisely, four positions indicated by lines in the air region are utilized for simulation, as shown in The comparison result of the analytical model and the numerical computation is presented in The objective of this study is to propose one novel tubular linear machine with hybrid magnet arrays and multiple layers of windings. It could be implemented for actuation or motion sensing depending on particular tasks. The employment of hybrid magnet array with Halbach and alternatively magnetized radial poles helps to enhance the magnetic flux density in the radial direction, and thus increase the current signal strength or force output. Furthermore, the utilization of multiple windings offers the redundancy property, and thus increases the system reliability significantly. Based on the proposed topological design, the magnetic vector potential is formulated analytically from governing equations. The flux distribution is then obtained from the curl of the potential. Numerical computation is conducted to validate the analytical model. It shows that the analytical model agrees with the numerical result well. In addition, the variation of magnetic flux density in the linear machine is consistent with the magnet patterns. The proposed structure topology and developed analytical model could be employed for subsequent study on current signal or force generation, and real-time motion control.


Underwater Wireless Sensor Networks (UWSNs) have intrinsic challenges that include long propagation delays, high mobility of sensor nodes due to water currents, Doppler spread, delay variance, multipath, attenuation and geometric spreading. The existing Weighting Depth and Forwarding Area Division Depth Based Routing (WDFAD-DBR) protocol considers the weighting depth of the two hops in order to select the next Potential Forwarding Node (PFN). To improve the performance of WDFAD-DBR, we propose DOlphin and Whale Pod Routing protocol (DOW-PR). In this scheme, we divide the transmission range into a number of transmission power levels and at the same time select the next PFNs from forwarding and suppressed zones. In contrast to WDFAD-DBR, our scheme not only considers the packet upward advancement, but also takes into account the number of suppressed nodes and number of PFNs at the first and second hops. Consequently, reasonable energy reduction is observed while receiving and transmitting packets. Moreover, our scheme also considers the hops count of the PFNs from the sink. In the absence of PFNs, the proposed scheme will select the node from the suppressed region for broadcasting and thus ensures minimum loss of data. Besides this, we also propose another routing scheme  in which multiple sinks are placed at water surface, but one sink is embedded inside the water and is physically connected with the surface sink through high bandwidth connection. Simulation results show that the proposed scheme has high Packet Delivery Ratio (PDR), low energy tax, reduced Accumulated Propagation Distance (APD) and increased the network lifetime. Underwater Wireless Sensors Networks (UWSNs) have numerous applications in diverse fields such as submarine detection, disaster prevention, oil/gas spill monitoring, off-shore exploration, and military target tracking. The characteristics of UWSNs e.g., high error rate probability, large propagation delay, floating node mobility and low communication bandwidth are totally diverse compared to terrestrial networks. Unfortunately, due to the dynamic nature of links, the connectivity of the sensor nodes cannot be assured and the reasons include rapid changes in network topology, variations in temperature, multi-path fading, environmental noises and interferences . Since rSelection of forwarder by computing the optimal average number of PFNs of the forwarding nodes,Calculating optimal transmission power adjustment based upon more distant node from the source node in potential forwarding region,Finding the alternate node from the suppressed region for the case if source node is in a void,Carrying out packet holding time calculations to assign priorities,Finding the nearest sink for the case if one of the sink is embedded underwater.Contributions: The contributions of our work have been summarized in the itemized text below: (1) The optimal set of mapped values for number of potential forwarding nodes and number of suppressed nodes has been investigated; (2) Significant energy is saved due to optimal route discovery mechanism; (3) Additional energy conservation achieved by dividing forwarder region into transmission power levels; (4) An optimal solution provided to cater for the problem of voids and energy holes; (5) Performance parameters included in formulating the holding time i.e., number of potential forwarder, number of suppressed nodes, hop count; (6) Significant improvement in end-to-end delay achieved by readjusting the position of sink nodes; (7) Traffic congestion sorted out by averaging potential forwarding nodes which forms the basis of item 2. To implement the above mentioned contributions, we follow the following steps:The rest of the manuscript has been structured as follows. The detailed discussion regarding previous work on routing protocols in UWSNs is carried out in In this section, we first review some related works on routing protocols in Underwater Acoustic Sensor Networks (UASNs), and will discuss their pros and cons. Then, we discuss the differences between WDFAD-DBR and proposed DOW-PR routing protocol.The most important and recognized property of Wireless Sensor Network (WSNs) is Energy efficiency. There are many types of terrestrial WSN protocols i.e., Directed Diffusion , Two-TieRouting protocols for UWSNs are categorized into four classes. The first such class is that of Flooding Based Routing (FBR) protocols, which includes HH-VBF, FBR, DBR, H2–DAB, DFR, etc. The second is multipath based routing, which include protocols presented by Winston et al. , Dario PGeographic based routing protocol such as VBF, HH-VBF requires a location information of the network where the nodes are deployed to send a packet to the centralized station from the source node. In VBF , a routiIn , Hwang eESEVBF   scales aIn FBR , the unnIn DFR , the autAnother routing protocol belongs to Communication path based routing protocol, whose scheme is abbreviated as Relative Distance Based Forwarding (RDBF) and is introduced in . This scA clustering scheme is used in ,23 for rTwo types of holes are created in wireless sensors network, one is a void hole that occurs due to unavailability of forwarder nodes, and the other is an energy hole that occurs due to the imbalanced data traffic in the network. The creation of a hole is a major factor in degrading the performance of the entire network. In this regard, Zahid et al.  proposedSherif et al.  authors The objective of these two routing protocols i.e., Round-Based clustering (RBC)  and LinkWan et al. propose PSFQ (Pump Slowly and Fetch Quickly) , in whicAnother routing protocol or routing scheme is Adaptive Mobility of Courier nodes in Threshold-optimized Depth-based (AMCTD) . This prH2-DAB protocol, which is also abbreviated as hop by hop dynamic addressing based protocol, is free of location information, as it belongs to a beacon based routing protocol class, as localization information of the node is costly, so, in this way, it reduces the cost of hardware. This scheme counts the hop number from the sink nodes present on the surface, and assigns a distinct address to all sensors that are part of the network by using the beacon mechanism from the nodes present on the surface (sink nodes). The node that has larger dynamical and distinct address will forward the packet towards the node that has a dynamically smaller address, up until it reaches the destination node or sink node. In , this scIn , mutilpaThe authors in  proposedIn , the autx, y, z-coordinates among nodes. Thirdly, the collision of the packets is investigated while contending the channel at the MAC layer.First and foremost, the problem of void holes (absence of forwarder in the transmission range of the source node) occurrence is exploited by the authors in our baseline paper i.e., WDFAD-DBR . The desTo improve the performance of WDFAD-DBR, we propose a state-of-the-art DOW-PR routing protocol in which we divide the transmission range into different transmission power levels while selecting the next forwarding node. The source node searches for the optimal power level for packet transmission.We also consider the additional parameters i.e., number of PFNs and number of suppressed nodes. WDFAD-DBR does not consider the above-mentioned parameters due to which a network consumes a significant amount of receiving energy, especially in dense networks.Along with other parameters, our scheme also considers the number of hops traversed by the packet initiated from the source node. Consequently, DOW-PR optimizes the shortest possible path and thereby improves the end-to-end delays.WDFAD-DBR does not provide any mechanism for void hole occurrences at the second hop forwarder. Our proposed protocol DOW-PR will select the node for broadcasting from the suppressed nodes when there is no PFN available.In DOW-PR, we also propose another system  in which multiple sinks are placed at water surface, but only one sink is embedded inside the water and will be physically connected with the surface sink through high bandwidth connection.In this paper, our proposed protocol DOW-PR focuses on selecting the optimal forwarder. This is very similar to the WDFAD-DBR. Much like WDFAD-DBR, DOW-PR also considers the weighting sum of depth of the current and the next expected hops’ sensor nodes. The novelties of the proposed protocol that differentiate themselves from counterpart WDFAD-DBR is mentioned in itemized text as follows:H is the combination of depth difference h between the source node and next PFN and the depth difference h1 between the PFN at hop 1 to the next expecting PFN at hop 2. However, WDFAD-DBR does not consider the number of suppressed nodes and number of PFNs of a source node, which consumes a significant amount of receiving energy. The reason behind it arises from the fact that a large number of PFNs result in receiving the packet as well as the high probability of duplicate packets generated at the first hop and hence excessive transmission energy wasted. The second important reason is that WDFAD-DBR does not consider the hops number for a packet to travel through. In case of a void hole i.e., when the forwarding node does not exist or the existing forwarding node does not have enough energy to communicate, WDFAD-DBR will drop the packet straight away and therefore Packet PDR degraded.The proposed protocol considered the number of suppressed nodes, number of PFNs, and hop count of each potential forwarder as well as the weighting sum of the two hops neighbors. For instance, if considering node S as the source node and nodes A and B are the next hop potential forwarding nodes, as shown in The WDFAD-DBR protocol abbreviates the priorities of PFNs in designing the holding time of the received packets by considering the accumulative depth differences of the potential forwarding nodes at hops 1 and 2 . WDFAD-DSink Node D: A UWSN sink node  is a type of node that is placed at the ocean surface or embedded inside water. Primarily, its function is to collect data from the sensor node and forward it to the base station through high speed radio link. These sinks or destination nodes can be static or mobile. Let D be a set of network sinks, then:Transmission Range : Potential Forwarding Zone (PFZ) is the hemispherical region whose radius is equal to a b Neighbors of node i that are in PFZ of S:The following notations are used in our proposed DOW-PR scheme:Firstly, the holding time of packet p at node i refer to . Node i The second reason for generating the duplicate packet is the hidden terminal problem. In a hidden terminal problem, the source node broadcasts and the potential forwarding nodes receive the packet. The problem occurs when the highest priority node broadcasts the packet while some of the potential forwarding nodes of the source node are not in the range and thus do not receive the duplicate packet, which causes these packets to be generated.Thirdly, relaying packets over multiple hops might result in a failed delivery of the packet to its destination because of high error rate of the acoustic channel, path losses and channel impairments. Duplicate packet generation and transmission become imperative because of the above-mentioned scenarios.Primarily, the duplicate packets are generated due to the following facts:In this section, we describe the network architecture, division of transmission range in different transmission power levels, and selection of suppressed node in the absence of potential forwarding nodes.The network architecture of DOW-PR protocol is composed of sink nodes, relay nodes and anchored node as shown in c represents the velocity of the acoustic signal in m/s , T represent the temperature in degree Celsius, S is the salinity in parts per thousand and D represents the depth in meters. The sound speed increases with the increase in temperature as shown in Different factors affect the speed of acoustic waves i.e., temperature variation, pressures at different layers of the sea and salinity of the water. Mathematically, it can be related as : c=1446.Channel geometry and its reflection and refraction properties influence the impulse response of an acoustic channel. The total count of major paths for propagation and their relative delays and strengths are also determined by these characteristics. Strictly speaking, the number of signal echoes is infinitely large, but after discarding those which have undergone multiple reflections and thereby lost much of their energy, we are left with only a few significant paths. The longest path delay governs the total multipath spread, which is to the tune of tens of milliseconds. Such values are usually reported in shallow-water experiments . The disd is defined by the following formula [The acoustic channel attenuation in UWSNs over  formula :10logA. TID field is a two-bit number that differentiates between the packets. The TID for NR is “00”. SID abbreviated as ID of the source and it is broadcast in the neighbor request message. DP represents the depth of source node and VA is a one bit number represents the void hole announcement. The value of VA will be true if the source found a void hole. ACK packet is sent in reply to neighbor request means the neighbor node send its information. The format of ACK is ACK . The TID for ACK packet is “01”, SID presents the identification ID of the current neighbor sensor and DP is the depth of node sending ACK packet. DATA is the real data and it has header and payload. The format of DATA is . The TID value for DATA packet type is “10”, SID is the source ID, DID represents the destination address, DP represents source depth and PID representing packet sequence number. The neighbor request and Acknowledgment packet has smaller size than the DATA packet.There are three various types of packets in DOW-PR routing protocol, which are NEIGHBOR REQUEST, ACK and DATA. The source node uses packet The proposed protocol divides the transmission range into six different transmission energy levels as shown in WDFAD-DBR selects the route based upon the weighting sum of depth difference between first and second hop PFNs. WDFAD-DBR drops the packet when there is no PFN(s) found and that means the data is lost. The source node S finds PFNs by sending a neighbor request packet. However, if the source node does not have any PFN, then the node for forwarding the packet will be selected from the suppressed nodes refer to . The selWhen neighbors of a source node receive data packets, it decodes and extracts the depth information of a source node and compares it with its own depth field DP. If DP value of the receiver is greater than DP value of the source node, and also the void announcement VA field has a value of 1, then it will forward the packet after necessary holding time calculation when no PFN is available to source. For the case, if PFNs are available, then each PFN will calculate the holding time according to the Fitness Function (HH) value, which is described below. The proposed scheme not only considers the sum of depth difference of the two hops (H), but also considers the number of PFNs (h is the depth difference of the source node to its PFN and h1 is the depth difference of the PFN to the next expected hop and To find the Fitness Function (HH) value, we mapped the The holding time is a function of the fitness value:Let For Node A: H = 8, For Node B: H = 16, For Node C: H = 12, According to WDFAD-DBR, node B will be selected as a next forwarder, but it has a large number of PFNs, which will consume a lot of receiving energy and generate a large number of duplicate packets. In DOW-PR protocol, the node having highest Fitness Function (HH) value will be selected as the next forwarder. Thus, Fitness Function (HH) calculates for Nodes A, B and C as follows:Node A:Node B:Node C:If source node S broadcasts a packet, then all the neighbor nodes i.e., A, B, C, M and N shown in The holding time between two neighboring nodes should be different in such a way that the forwarder node that has a greater fitness function (HH) value transmits the packet before the transmission of the same packet from other nodes. For instance, if node A has the highest fitness function value, then it will transmit prior to node B. Upon the receiving duplicate packet from node A, it simply drops the packet. The following equation must be satisfied to avoid duplicate packets:Substituting Equation  in EquatAccording to the the triangle inequality theorem that the length of each side is less than sum of lengths of the other two sides, and greater than the difference between these lengths, thus k varies between 0 and R, as it depends on −2RBy solving the equation and putting the values in , we haveThe node having the highest fitness function (HH) value will be selected as a next forwarder. For instance, node A will calculate the holding time and start timer. When the timer is expired, then node A will forward the packet. If the other nodes in the range of A, i.e., B receives the duplicate packet during the holding time, it will drop both the packets because it means the original packet is already transmitted. The holding time is inversely proportional to Our proposed DOW-PR scheme divides the whole transmission region into two levels of nodes distribution. One level in which the nodes are in closest proximity to the surface sinks and the other is the nodes that are in closest proximity to the sink deployed underwater. There are nine sinks that are placed at the sea surface, while one is placed inside the water. The anchored nodes are fixed at the bottom that can generate and transmit a packet towards PFZ. The relay nodes are transportable with the water current in horizontal direction. These nodes are capable of generating, forwarding and receiving a packet from other nodes. Whenever the node transmits or receives a packet, the first and foremost step followed by the forwarder is to calculate its distance with the sink set D. The node compares the distance between itself and the rest of the sinks from the set D sequentially and finds PFNs lying in the hemisphere in the direction of the minimal distinct sink. The direction of data packet flow will be towards the sink lying at its closest proximity. If the separation between forwarding node and sink deployed on the sea surface is less than the sink deployed underwater, then the holding time computation will be carried out for the nodes present in the hemisphere in the direction of the surface sink D. On the other hand, if the source node is in closest proximity to the embedded sink The above-mentioned phenomena can be further elaborated by a scenario shown in Algorithm 1: Algorithm for selecting the forwarder among potential forwarding nodes.In this section, the detailed simulation analysis of the proposed dolphin pod scheme in contrast to WDFAD-DBR is presented in addition to the simulation results in the enhanced version  compared with our own dolphin pods routing protocol. DOW-PR has been developed in MATLAB  and simulations are carried out to test the performance compared to WDFAD-DBR. We have used all the underwater environment settings as in WDFAD-DBR.We deploy 100–500 network nodes in the three-dimensional volumetric space of 10 Km × 10 Km × 10 Km , as shown in Equation  to find Hop count mechanism gives a hops number to each node according to the sequence/serial numbers of depth levels between the node and the sink. The PFNs of the source node are those nodes that have a smaller depth than the source node and lies in the range of the source node. Similarly, the nodes that are in the range of the source node but have a larger depth than the source node are called suppressed nodes. All those nodes having a sink in its range have a hop number equal to (hp1) and the nodes having depth greater than maximum transmission range PN and lesser than twice of the maximum transmission range will lie at hop 2 (hp2). Similarly, the mechanism continued until the sea bed reached. For example, from Data delivery mechanism is used to forward the generated or received packets to its destination. Every node can generate a packet. If the closest proximity sink is present in predefined maximum transmission power range of the source node, then it relays the packet to the sink and it is therefore successfully delivered to the destination. All the sinks are communicated/connected via high speed radio links. If the sink is not in the range, then the Algorithm 1 selects the best node for forwarding according to the fitness function (HH). The fitness function is set in such a way that the forwarding node has a higher weighting sum of depth difference of the two hops, average PFNs number, least suppressed node numbers and having a lower hops count value.Each node is assigned a unique HH value calculated through a fitness function in Equation . When thded sink  as compaWe evaluate DOW-PR against WDFAD-DBR and DBR in term of APD, energy tax, end-to-end delay, packets dropped number and alive nodes number for different ranges of Performance Metrics: The proposed system will define a new metric called Alive Nodes Number (ANN) besides the common performance metrics, i.e., APD, End-to-End Delay (E2ED), Energy Tax (ET) and PDR.Alive Nodes Number (ANN): A node having enough energy that it can receive, process and forward the packet is called alive node. To categorize the alive nodes, the threshold Packet Delivery Ratio (PDR): PDR is the ratio of the packets received by the sink to the total packets generated by the network. The packets may be received multiple times, so this redundant packet is considered to be a one distinct packet:End-To-End Delay (E2ED): The E2ED is defined as the average time taken for a packets transmission from the instant the source node started transmission to the instant it is delivered to the destination. E2ED consists of transmission delay, propagation delay, processing time and holding time. Due to the multiple-sink nature of the network, a packet may be received by more than one sink, so the shortest time will be considered as end-to-end delay.Energy Tax (ET): The energy tax is defined as the average energy expenditure per node when a packet is successfully delivered to its destination. It includes the energy for sending packet, receiving packet, computational energy, and the idle state energy shown in the equation below:Average Accumulated Propagation Distance (APD): APD is defined as the average accumulated distance of each hop of all the packets that are successfully delivered to the sinks. There is a multi-sink network environment in which more than one sink can receive a packet, so the shortest accumulated propagation distance is considered as a final accumulated propagation distance.h is the hop number of packet from source node to sink and The APD can be found by the following mathematical equation:In this section, the simulations are performed upon the dolphin pod routing in which all the sinks are placed on the water surface without any sink embedded Moreover, dolphin pod routing assigns weight both to the packet advancement as well as to the network traffic density in such a way that priority is given to the less dense traffic path at the cost of packet advancement. The fitness function (HH) value will be less for the more dense path in which the probability of traffic density is high. Therefore, the dolphin pods scheme selects the path where the forwarder of the source node has a higher value of weighting sum of depth difference of the hops (H) , averageNext, we investigate the energy tax comparison of a proposed dolphin pod with WDFAD-DBR protocol. When compared to idle listening, packet reception, sensing and processing of operations, in underwater acoustic networks, transmission of a packets is the most energy consuming operation. Transmission of data packets accounts for most of the energy consumed due to their large size when compared to control packets. The above argument is already validated through experimental measurement by the authors in . Energy Secondly, our scheme exploited the adaptive nature of data transmission power, which depends upon the maximum displaced node within the transmission range refer to . ConsequMoreover, the proposed scheme in this paper selects the next expecting hop by considering the weighting sum of the depth difference of the two hops, the PFN number, suppressed nodes number and the hop number of the expected next forwarding node, which reduces the total energy to a very low level. Energy tax is directly proportional to the total energy consumption, and inversely related to nodes number and number of packets generated  to be collected by the sink at the sea surface. On the other hand, in the whale pod scenario, the same packet will be received at the embedded sink and propagated through the distance of 2.5 km at the most.Last but not least is the important metric end-to-end delay that needs to be optimized especially when there is run-time data needed in the network. The end-to-end delay has been investigated for both DOW-PR scenarios. The simulation results show the obvious improvement in end-to-end delay and this is because of the same argument described repeatedly in the above text i.e., the locally available embedded sink reduces the propagation distance. For instance, if the node at the seabed generated a packet, then it has to propagate at least the full Although our proposed protocol outperforms the aforementioned performance metrics, we observe some limitations and constraints in certain specific scenarios as discussed below:In sparse networks, there are probably fewer PFNs present at each node in the network due to which overall improvement seems to be negligible; however, the computational cost still becomes greater. The abovementioned constraint in DOW-PR will become even more pressing when transmission range is also low. WDFAD-DBR focuses on the packet advancement at the first and second hop. It works well compared to DOW-PR in delay intolerant ad hoc underwater networks, where prolonged network lifetime is not required. DOW-PR has other limitations in the scenario where the source node is in a void and its predecessors also don’t have PFNs other than the source node. In this case, the node will drop the packet or have progressive backward transmissions. In sparse networks with low average data packet generation, a low number of duplicate packets occurs due to which energy losses reduce in both DOW-PR and WDFAD-DBR, but DOW-PR will carry out more complex computational algorithms. In sparse networks, the probability of the void hole occurrence is high due to which DOW-PR will produce a huge number of void announcement messages, which will be disseminated in the entire network. It has been observed that, contrary to WDFAD-DBR, DOW-PR undergoes additional energy loss in transmitting void announcement control packets and thereby collision probability is also increased. In the future, the authors plan to undertake research that will overcome the above-mentioned constraints.A dolphin and whale pods routing protocol (DOW-PR) has been proposed in this paper. There are two versions of the proposed protocols i.e., dolphin pods and the whale pods. Whale pods routing protocol is the further enhancement of the dolphin pods routing. Basically, the proposed scheme enhanced the performance of the metrics simulated in its state-of-the-art counterpart routing protocol i.e., Weighting Depth Forwarding Area Division Depth Based Routing (WDFAD-DBR) protocol. DOW-PR provides a reduction in energy consumption, increasing PDR, and minimizing end-to-end delay. In the proposed scheme, it explores the role of the parameters like potential forwarding nodes number, suppressed nodes numbers and hops count value in designing the holding time equation. Moreover, the values of the above-mentioned parameters have been mapped  into arbitrary values and that are also tested for simulations. The investigations through simulations showed that dolphin pods routing beats the WDFAD-DBR, on average improving by 31.5% of energy tax, 6% of PDR, and 24.6% of E2ED. However, certain performance trade-offs have been observed and listed in In the future, we will investigate the other sets of arbitrary values for mapping the actual values of potential forwarding nodes number, suppressed nodes number and hops count. Other than this, we will deploy a greater number of movable underwater sink nodes.


Routing in Vehicular Ad hoc Networks (VANET) is a bit complicated because of the nature of the high dynamic mobility. The efficiency of routing protocol is influenced by a number of factors such as network density, bandwidth constraints, traffic load, and mobility patterns resulting in frequency changes in network topology. Therefore, Quality of Service (QoS) is strongly needed to enhance the capability of the routing protocol and improve the overall network performance. In this paper, we introduce a statistical framework model to address the problem of optimizing routing configuration parameters in Vehicle-to-Vehicle (V2V) communication. Our framework solution is based on the utilization of the network resources to further reflect the current state of the network and to balance the trade-off between frequent changes in network topology and the QoS requirements. It consists of three stages: simulation network stage used to execute different urban scenarios, the function stage used as a competitive approach to aggregate the weighted cost of the factors in a single value, and optimization stage used to evaluate the communication cost and to obtain the optimal configuration based on the competitive cost. The simulation results show significant performance improvement in terms of the Packet Delivery Ratio (PDR), Normalized Routing Load (NRL), Packet loss (PL), and End-to-End Delay (E2ED). Vehicular Ad hoc Networks (VANETs)  are a coAdjusting routing protocols for V2V communication network in order to satisfy various QoS requirements in applications was studied in ,7,8. HowDue to the high-level perspective, MANET is not suitable in VANETs, it needs to be developed to meet the specific characteristics of VANETs. Different methods to tune the routing parameters had previously been introduced to ensure a high level of performance in the dynamic network , yes mosTuning routing configuration parameters is one of the most common strategies used to keep track of neighboring node status . A numbeIn this paper, we present a framework model designed specifically to tune the routing configuration parameters in high dynamic mobility environment. This model exploits the network resources to improve the stability and reliability of routing packets between vehicles, which it index the QoS metrics as a function to balances the QoS requirements and the nature of the dynamic mobility impact. This balance reduces the trade-off between the communication cost and time needed to deliver packets successfully. In addition, we present The routing protocol for vehicular networks in urban environment called Balanced Optimized Link State Routing-Particle swarm optimization (BOLSR-PSO). This protocol is the end result obtained when the framework tune Optimized Link State Routing-Particle swarm optimization (OLSR-PSO), which improved its efficiency using the network resources by maximizing PDR, Throughput, and minimizing both NRL and E2ED.The remainder of this paper is organized as follows; The ordinary OLSR RFC-3626  routing The QoS constraints do not consider the classical routing protocols when selects a path, authors in  studied A comprehensive study about the impact of data flows on achieved routes validity used CBR data flow between vehicles to study the impact of different mobility models on the performance of the routing protocol in Vehicular Networks . For thiTuning routing parameters is an important issue to enhance the exchanging route information between neighboring nodes correctly , and leaThe framework approach was introduced to obtain the knowledge about the current mobility as a main issue in dynamic mobility, which used the video-streamed base on UDP in order to optimize routing decisions and reduce the influence of path losses . In 11]11], the For a self-optimizing scheme to balanced routing resources in wireless sensor networks, the authors used Ant Colony Optimization to utilize and optimize network resources . Most ofIn summary, The primary objective of this work is to define the best parameter values for the routing protocol in VANET environments. These values are obtained by sensing the best response time for any change in the topology network, especially in terms of the overhead and end-to-end delay.The framework model should offer a comprehensive view of network environment as close as possible to the real world environment. This model is carried out by different stages and procedures which interact automatically to obtain efficient routing configurations. In order to obtain fully the information of vehicles network communications, each scenario is run to compute the communication cost of the whole vehicles connectivity in term of PDR, throughput, NRL, and E2ED. This is done through network simulation which link OLSR with IEEE 802.11p and VANET scenarios. Then, the connectivity cost is calculated as a cost function. This cost is used as a main factor in PSO algorithm to generate an optimized solution (Configuration of parameters).A link state routing protocol was proposed in  for discIn OLSR, the MPRs are selected using the HELLO-interval messages and are only responsible for forwarding TC messages to special nodes in the network. This feature ensures a minimum level of packet broadcasting over the whole network. Therefore, the performance of OLSR is greatly influenced by the number of HELLO-interval and TC messages and their interval time. Furthermore, increasing the rate of Hello-interval and TC messages leads to more frequent updates in the topology table thereby resulting in more routing overhead . The HELThis work tunes the most important configuration parameters, which have a great impact on network performance as proposed in the ordinary OLSR. As a result, these parameters define the degree of time allocated, which can be selected from a ready-made group of eight levels for re-routing message information that is equal to 3 by default. The interesting features of OLSR  made it PSO is an adaptive algorithm developed by Dr. Eberhart in . The maii-th in particle i = j = j-th dimension of the problem in the domain of the search space. These particles are distributed randomly in the search space, and the optimal solution is made depending mainly on updating the particles position with each iteration.i according to the j-th dimensional component.i according the j-th dimensional component.i according to the j-th dimensional component.j-th dimensional component.In order to initialize the population, we need to define the group of i is presented as f denote the fitness function needed to be optimized. Then the local best of particle i can update its velocity and position at iteration t as.i at j-th dimensional.The basic operation of PSO is more appropriate to solve dynamic mobility problem, and it is used to mange the network resources . To findThe found in ,38.To detect a fit configuration for routing protocol, we introduce a reliable and robust communication cost function to aggregate the weighted cost of each factor in the network to a single scalar value. This value function has been defined to maximize the network connectivity during the path discovery phase and to reduce the routing overhead. Our approach can take the advantage of the communication capabilities among vehicles to provide an accurate status for different urban scenarios. The overall routing performance is influenced by numerous factors such as the degree of node mobility patterns, network density, traffic load, frequent topology changes, and wireless channel effects. Moreover, this function balances the trade-off level between the QoS requirements and the routing limitations during the route discovery mechanism, which achieves the best overall performance in respect to each performance metric. The advantage of this strategy is its ability to independently examine the different metrics for a variety of urban scenarios. In addition, the proposed model provides an efficient method for comparing two or more effective factors, which index the set of response metrics in one function, as shown in The performance model represents arithmetically the weighted response of each performance metric, comparing the communication cost with the respective upper and lower bounds of each factor. In the literature, a number of studies address the routing configuration problems in the high dynamic network, however, none of these studies considered balancing routing performance according to the nature of VANET environment. This work maps factors of performance metrics to a single function based on balancing the trade-off between the QoS constraints and the degree of dynamic mobility. This model is carried out by coupling two different stages: an optimization procedure and a simulation stage. We considered Throughput, Packet Delivery Ratio (PDR), End-to-End Delay (E2ED) and Normalized routing Load (NRL) as the main QoS factors to calculate the communication cost (fitness function).Let topology . The quai refers to the interact response when there is any change in one of the varying factors – O. Therefore, the arithmetic average of summation can be formulated as a weighted ratio of the response metrics according to the respective upper or lower bound. Where f represents the fitness cost of communication that quantifies overall system performance at each iteration. To define the upper or lower bounds between 0 and 1, the equation of cost function f can be formulated as follows:To define the best-fit formula that is able to reflect the correct trade-off status between the OLSR configuration and frequent change in network topology, we need to identify the appropriate QoS constraints to control the values for each metric. Let f is paramount to maintain the quality of solution. The ratios of i deviates from its respective upper bound i from its respective upper bound The objective of the cost function The proposed framework model is comprised of three stages: The network simulation with different urban scenarios, communication cost function, and PSO optimization algorithm. These procedures generate optimal configurations of OLSR protocol for a given VANET scenario. In each urban scenario, all mobile nodes are equipped with IEEE 802.11p network interface card which give each node the ability needed to send and receive messages according to Wi-Fi constraints. This ability is conditional by several factors such as limitation of distance, bandwidth availability, link life time, directions, and the varying speed of vehicles. This is because of the routing protocol discovers the path through the vehicles based on the network topology, which build it by periodically broadcasting control messages. These messages are used to update and maintain the network topology information within specific period time. In such VANET environments, this time is not compatible with routing configuration parameter values defined in , the number of packets received by destination nodes to the number of packets sent by the source node (PDR), the number of forwarded packets divided by number of data packets received (NRL), and the ratio of time difference between every packet sent and received to the total time difference over the total number of packets received (E2ED). In order to save network bandwidth, and improve the transmission ability of the network, the proposed equation is made to reflect correctly the deviating values of response metrics from its respective performance metric bound. The performance metrics values are placed in the equation in the form of numerator and denominator to maximize and minimize the performance metric. Additionally, the deviating values obtained from the equation reflects the balance of the trade-off between the QoS requirement and the efficiency of routing, these values plays an important role in balancing the weight of communication costs. The PSO algorithm calculates the optimal fitness value using the communication cost obtained from cost function. The communication cost is associated with each particle which affects the behavior of particles to find the global fitness value of a single parameter at a time. These values represent the new value of BOLSR-PSO configuration parameters. This process continues to happen once a new communication cost is calculated until an optimal global fitness value is obtained for each parameter. The new values rising from this process are the configuration parameters of BOLSR-PSO .Nowadays, there are different approaches developed to solve the complex problem of VANET simulation. There are numbers of road traffic simulators which generate NS-2 format traces file, but the most comprehensive ones use OpenStreetMap (OSM)  such as In order to obtain results close to the real world, we have defined 10 realistic vehicular mobility scenarios. This scenarios will be evaluated by an existing specific VANET simulator as suggested in . The criWe take into consideration the relation between the number of network nodes and the selected area, vehicle speed movement, limit of covering range, available bandwidth, and simulation time. For example, the number of nodes should be higher in highway wireless network environments. The reason of large scale density is to reduce the likelihood of packets loss due to vehicles traveling at higher speeds than in urban areas environments. In our scenarios, there are 40 vehicles moving and exchange information data about routes in an area of 1400 m × 1200 m, and the vehicles travel on the urban scenario with varying speeds of 10–50 km/h, and the transmission power range is adjusted to 250 m. The setting of VANET scenarios are adjusted automatically by SUMO simulator.In order to investigate the efficiency of our solution, we implemented and compared the OLSR-PSO , UM-OLSRThe vehicles move through urban roads at varying speeds of 10–50 km/h. The transmission power range is adjusted to 250 m according to the characteristics of the network system (IEEE 802.11p) interface card . The simIn this simulation, we performed 40 independent runs of every scenario in order to ensure the accurate values of the average communication cost. This cost should be as close as possible to real world environment, where the quality of cost is evaluated using six network data loads  in this area. We used the most widely accepted parameters, such as average E2ED, PDR, NRL, and PL.We discussed the framework proposed to augment OLSR routing protocol efficiency, which ultimately proved to balance QoS metrics. These performance metrics were studied to find the impact of different OLSR configurations on the proposed fitness function. The trade-off between accuracy of routes and cost in the proposed equation manages correctly the capacity of links between the vehicles, therefore, reducing the necessary number of packets exchanged, reducing link failure and help in avoiding congestion. In our BOLSR protocol, whenever a vehicle aggregates the neighboring vehicles information at a specific point of time, it uses HELLO-interval and TC messages to estimate the quality of communication state in the routes discovering process. It is important to note that the parameters that are used in OLSR protocol mange this process at limited time. This time must be enough to collect, process, calculate, select routes, and broadcast route information. If the time interval for each parameter was not enough to received packet during this specific period, then, the probability of link failure increases. This may lead to packet loss and increase end to end delay.The behavior of each algorithm shows the capability of delivering, gathering, and processing route knowledge of different dynamic mobility patterns. The effectiveness of each approach is described by the functional relationship between the QoS metrics that influence the performance routing protocol and the mathematical approach. The proposed protocol help to improve the operations functionality to reduces link failures and conjunction problem by collecting accurate and up-to-date data about VANET network timely. Therefore, the proposed protocol enhances the stability and flexibility of the network by balancing between the QoS requirements and the OLSR configuration constraints. This work introduced an ideal solution to fulfill the QoS requirements for solving optimal routing configuration problems. This solution satisfies various demands of the VANET network by adjusting the routing configuration, it also can balance different response metrics effectively which can be integrated into a single scalar value that gives a better evaluation and comparison. In an urban environment, the proposed BOLSR-PSO routing protocol is able to utilize the network resources information efficiently and provide smooth routing data packets between the vehicles. It gives better performance compared to the standard OLSR RFC-3626, OLSR-PSO, OLSR-Gomez and RAND algorithms. The simulation results showed that the proposed configuration significantly improves routing performance under different conditions of traffic density. As a future work, we plan to design scalable method that can efficiently deal with high topology change under different network condition. This work takes into account the position of relay selection nodes and Roadside Units (RSUs) to evaluating the quality of link connection.


The purpose of the study has been making the orthodontic space maintainers in PEEK polymer (Polyetheretherketone) through a digital workflow. New digital technologies are taking hold in diagnosis, therapy and in dental laboratories. The digital world can help dentist in diagnosis and therapy: -diagnosis through the acquisition of radiographic images (CBCT) or scanners which allow the creation of 3D digital models – about therapy thanks to dental CAD CAM system. It consists of design devices through an dedicated software CAD and then realize devices through CAM system. We used digital system to improve the quality of the treatment and reduce costs. Peek polymer, subject of studies in recent years, thanking to its characteristics, resulted useful for this study. According to a nine month- follow up the devices were found comfortable, satisfying, personalized and minimally visible for the patients. These devices were found suitable to maintain the space. About material, thanks to its dimensional stability, mechanical strength but specially, thanks to its biocompatibility, PEEK was found as a very good material to build space maintainers. The workflow allowed a simulation of the treatment plan with a better collaboration and acceptance of the patient. Digital system reduced the systematic mistakes during the various phases and the production time. The digital system saved space creating a virtual plaster casts collection. Key words:PEEK, CAD/CAM system, space maintainers, orthodontic prevention. Plasma treatment has no impact on bond to resin cements . The scanned object was hit from all sides by light beams and then filmed with micro cameras. Since the scans are several and detected over the entire model the result was a cloud of points. The software connected the points and reconstructed a pattern of tiny polygons creating the virtual model.Step 2: Once got virtual model, we had the model in all the screenings. Thanks to CAD (Computer Aided Design) software we designed personalized devices. The model has been archived and imported directly into 3Shape Dental Design software system using the zoom tools, rotating and panning allowed to view the model from different angles and magnifications facilitating the analysis of the model. This system allows to design devices and to determinate a lot of variables such as the material thickness, retention, undercuts, the space for the cementation, the points of support Fig. .Step 3: At this point the file has been sent to the CAM and begun the construction of the building through milling Roland DWX-50 features 5-axis continuous movement, equipped with an automatic transmission of different tools. This is a manufacturing process by subtraction and thanks to these movements the block of chosen material was milled to get the form designed previously by software CAD (in about one hour). The three devices we made, were the following: lingual arch, band with loop and removable plate. The first patient was 8-year old child who needed a space maintainers to keep the space in the mandible o allow a proper eruption of the canines and premolar teeth.The workflow allowed us to get a peek polymer 1.3mm thick lingual arch, in about one hour, which could get in touch with facial lingual. The device was also composed by two orthodontic bands cemented on the first lower molars ( by cvi) Fig. . In the The last case shows a removable plate. The patient was 8 years old, had a supernumerary which interfered with the proper central incisor eruption. The supernumerary caused a delay of incisor eruption. Thanks to the central incisor’s eruptive force, the treatment plan was to extract the deciduous incisor and the supernumerary and to maintain the space during the permanent incisor’s eruption Fig. . Accordiet al. showed that peek has many advantageous properties useful for esthetic metal-free orthodontic wire despite lower esthetic properties (New research in dentistry such as digital technologies or tissue engineering are changing diagnosis and therapy . Digitaloperties . There a