The human foetus typically needs to rotate when passing through the tight birth canal because of the complex shape of the pelvis. In most women, the upper part, or inlet, of the birth canal has a round or mediolaterally oval shape, which is considered ideal for parturition, but it is unknown why the lower part of the birth canal has a pronounced anteroposteriorly oval shape.Here, we show that the shape of the lower birth canal affects the ability of the pelvic floor to resist the pressure exerted by the abdominal organs and the foetus. Based on a series of finite element analyses, we found that the highest deformation, stress, and strain occur in pelvic floors with a circular or mediolaterally oval shape, whereas an anteroposterior elongation increases pelvic floor stability.This suggests that the anteroposterior oval outlet shape is an evolutionary adaptation for pelvic floor support. For the pelvic inlet, by contrast, it has long been assumed that the mediolateral dimension is constrained by the efficiency of upright locomotion. But we argue that the mediolateral elongation has evolved because of the limits on the anteroposterior diameter imposed by upright posture. We show that an anteroposteriorly deeper inlet would require greater pelvic tilt and lumbar lordosis, which compromises spine health and the stability of upright posture. These different requirements of the pelvic inlet and outlet likely have led to the complex shape of the pelvic canal and to the evolution of rotational birth characteristic of humans.The online version contains supplementary material available at 10.1186/s12915-021-01150-w. Human childbirth typically involves a complex rotational motion of the foetal head, followed by the shoulders and rest of the body, as the baby passes through the birth canal Fig. A. The tiEvolutionarily, human pelvic morphology has been the target of many, partly antagonistic selection pressures. The size of the birth canal presumably evolved by trading off the advantage of a large birth canal for childbirth against the disadvantage for bipedal locomotion, thermoregulation, and particularly pelvic floor support , 11–20. We propose that not only the size but also the shape of the birth canal is subject to functional and evolutionary trade-offs between parturition, pelvic floor stability and locomotion. These selective factors, however, differentially affect various parts of the pelvis. The size and shape of the pelvic inlet is particularly decisive for successful parturition. Locomotion efficiency is assumed to be affected by the distance between the acetabula , 30, whiThe deformation of the pelvic floor in response to pressure increases with the average radius of the pelvic floor for a constant pelvic floor shape , which mWe tested this hypothesis by a series of finite element analyses (FEA) of idealised pelvic floor models that vary from oval to round, while keeping the area and thickness constant. Loaded with an increased physiological intra-abdominal pressure  or mediolateral (ML) direction equally reduced deformation, stress and strain. This symmetrical behaviour results from the geometrical symmetry of the flat and ellipsoid models as well as from the isotropic material properties adopted here. For the more realistic anatomical model, by contrast, the sagittal cross-section was not symmetrically shaped, with the maximum curvature located at the area of the anal sphincter rather than at the mid-point. As a result, the highest deformation was not observed for a circular model but for a mediolaterally elongated shape with AP/ML=0.83. The highest values of strain and stress occurred in models with AP/ML=0.71. An even more extreme ML oval shape only weakly reduced displacement, stress and strain. However, increasing the AP/ML ratio towards a more AP oval shape of the anatomical model led to a rapid decrease in all three measures. As our anatomical model still is an idealisation of the real pelvic floor, the actual pelvic floor shape leading to the greatest deformation may deviate from our estimate but is likely to have an AP/ML ratio smaller than 1 see the ‘’ sectionThese findings suggest that a mediolaterally elongated shape of the lower birth canal is particularly disadvantageous for pelvic floor support. The more anteroposteriorly oval the lower birth canal is, the more resistant the pelvic floor is in response to pressure. This is in agreement with clinical literature reporting that a mediolaterally wider lower birth canal predisposes to pelvic floor dysfunction , 38–40. size . Furthermore, the stability of the pelvic floor does not only depend on its size and shape. Parity, mode of delivery, age, obesity and weakness or injuries of pelvic floor tissue are important risk factors for pelvic floor disorders ) and providing different metabolic capacities during pregnancy [The relative strengths and actual trade-off dynamics of these antagonistic selective forces depend on biological, environmental and sociocultural factors that have changed during human history and partly differ among populations today (‘shifting trade-off model’ ). For inregnancy . Transitregnancy , 85. Henregnancy  have parThe anteroposterior oval shape of the lower pelvic canal is an evolutionary adaptation for pelvic floor support. By contrast, the mediolateral elongation of the pelvic inlet presumably evolved because of the limits on the anteroposterior diameter imposed by upright posture. We showed that an anteroposteriorly deeper inlet would require greater pelvic tilt and lumbar lordosis, which compromises spine health and the stability of upright posture. These different requirements of the pelvic inlet and outlet likely have led to the complex shape of the pelvic canal and to the evolution of rotational birth characteristic of humans.We assessed how changes in the ratio of anteroposterior to mediolateral diameters (AP/ML) of the pelvic floor affect the amount of displacement under physiological pressure conditions. We used three different idealisations of pelvic floor geometry: a flat membrane, a regular 3D oval-shaped hammock and a 3D membrane that resembles real pelvic floor geometry as it is suspended in the midplane and outlet of the birth canal. We refer to the first model as ‘flat’, the second model as ‘ellipsoid’ and the third model as ‘anatomical’ Fig. . The shaComputer-aided design (CAD) models of the pelvic floor were created as shells in SOLIDWORKS (© 1995-2019 Dassault Systémes). Their mediolateral (ML) diameter corresponded to the distance between the ischial bones at the points of muscle insertion on the ischial spines and was thus equal to the width of the midplane of the birth canal  of modern Europeans as reported by DelPrete . The ‘ba3 to each of the models [. The geometry was discretised using more than 3000 HEX 8 elements with an average element size of 2 mm. An implicit solution scheme using ANSYS Mechanical  was adopted to solve the quasi-static loading problem. The boundary conditions were identical across models and involved setting the mobility of the rim to zero in all three directions, while allowing for rotation. We assumed that the pelvic floor is at an equilibrium at the normal intra-abdominal pressure of 0.5kPa [. We therefore apply the difference of 4kPa between the normal and the Valsalva intra-abdominal pressure as an equivalent normal force to the entire superior surface of the mesh. This approach allowed us to validate our pelvic floor model , the maximum von Mises strain and the maximum von Mises stress (in MPa). The engineering term ‘strain’ is a dimensionless measure that describes the amount of extension the material experiences per unit length, while ‘stress’ denotes the amount of force experienced by the material per unit of its surface. A large strain magnitude implies that the material was stretched, compressed or sheared to a high degree. At the same time, a large stress signifies a high amount of energy that the material absorbed in order to achieve its deformation. The von Mises stresses and strains are theoretical values calculated from the three-dimensional stress and strain state of the material, therefore combining in a single parameter the maximum distortion energy . We ignoThe geometry of the real human pelvic floor is more complex than our anatomical model as it is neither homogeneous in thickness nor in tissue properties. Additionally, pelvic floor tissue properties vary due to individual genetic differences and change with age, hormonal status and pelvic floor training –100. TheAdditional file 1:Tab. S1. List of models and their AP/ML ratios used for finite element analysis. Tab. S2. FE model validation. Fig. S1. Stress-strain relationships for the three geometries  at the base dimensions. Fig. S2. Total displacement across all anatomical models. Fig. S3. Comparison of displacement maxima at the anterior and posterior compartments of the anatomical models and their total maxima.


In United States (U.S.), government-funded organizations, such as NLDAC, reimburse travel and subsistence expenses incurred during living-organ donation process. However, in Iran, there is a non-governmental organization called Iranian Kidney Foundation (IKF) that funds the direct and indirect costs of donors through charitable donations and contributions from participants in the exchange program. In this article, for countries outside the U.S. that currently use an equality approach, we propose a potential new compensation-apportionment approach (equitable approach) for kidney-exchange chains and compare it with the currently available system  in terms of the apportionment of compensation in a kidney-exchange chain to cover the expenses incurred by the initiating living donor of the chain in the act of donation. To this end, we propose a mechanism to apportion compensation among all participating pairs based on the equity approach by utilizing a prediction model to calculate the probability of graft survival in each transplant operation. These probabilities are then used to define the utility of any transplantation, considering the quality of each pair’s donated and received kidney in the chain. Afterward, the corresponding cost is apportioned by a mechanism based on the normalized differences between the utility of donated and received kidneys for each incompatible pair of the chain. In summary, we demonstrate that by utilizing the equitable approach, there is more fairness and equity in the allocation of resources in organ-procurement systems, which results in more satisfaction among incompatible pairs. Additional future prospective studies are needed to assess this proposed equitable approach for kidney-exchange chains in countries outside the U.S., such as Iran, that currently use an equality approach. The two currently available treatment options for patients with kidney failure are dialysis or kidney transplantation . AlthougPatients with an incompatible living donor can participate in kidney-exchange programs. Kidney exchange or kidney paired donation (KPD) involves the exchange of kidneys between living donors and recipients so as to facilitate transplantation of incompatible pairs and optimize available resource utilization. Blood group O recipients are often disadvantaged in this process ,7. KPD cThere are financial barriers for non-designated living donors, despite their altruism. Living donors face both direct and indirect costs for their act of donation. Direct costs are related to transportation, lodging and parking, whereas indirect costs include lost wages, use of paid time off, dependent care expenses and risks to job stability ,12,13,14Given to the current process of the IKF, the amount of money that should be paid from participants varies under different circumstances. To determine these amounts, the IKF tries to fund a part of compensation, usually about 30%, from the individual donors or organizations once the kidney-exchange chain and the initial donor are identified . The remEquality approach: equality is easily reached by allocating an equal amount of the living donor’s costs to all pairs participating in the exchange plan. We named this approach the equal compensation amount (ECA) approach.Equitable approach: unlike the ECA approach, this approach is complicated and aims to consider equity in the apportionment of the non-designated donor’s costs among the incompatible pairs in the exchange plan. Regarding the focus of this approach on fairness, it is named the fair compensation amount (FCA) approach.Regarding these definitions, we aim to develop a mechanism to adopt the FCA approach in compensation apportionment. We also compare the results achieved by this approach with those achieved by the ECA to determine which approach brings more satisfaction to participants in the chain. Note that the developed FCA approach can also be employed in transplantation systems in which government-funded programs have limited funding and cannot cover all expenses of living donors.The rest of the article is organized as follows: In Kidney exchange between incompatible pairs was first proposed in 1986 by Rapaport . The simAs mentioned earlier, chain kidney donation is another approach in kidney-exchange programs, which has been widely discussed in living donor availability ,27,28,29Prediction of future events has been a matter of attention for decades; however, prognostic studies only began to receive adequate attention a few years ago . PredictRegarding the mentioned limitations of kidney-exchange programs, the main contributions of this work are summarized below:We aim to (1) propose a new equity-based approach to achieve financial neutrality of the initiating non-designated donor in kidney-exchange chains in sharing the direct and indirect costs of the living donor between the participating incompatible pairs that can be considered outside the U.S., and (2) compare two different approaches, ECA and FCA, in terms of apportioning the required compensation among chain participants.To implement the FCA approach for the apportionment of the participant compensation, we must take the characteristics of all donated and received kidneys in the chain into account. To address this issue, we develop a mathematical mechanism that determines each pair’s share regarding the attributes its donated and received kidneys.The proposed mechanism determines the probability of graft survival by utilizing multivariate Cox regression survival analysis ,39, convTo define and formulate the problem under investigation, we first describe the problem and list its assumptions. Then, we discuss the methodology and approaches used to apportion compensation among the available pairs in a kidney-exchange chain.As mentioned in the preceding section, the purpose of this article is to compare ECA and FCA approaches in the operation of apportioning the compensation of external donors who starts a kidney-exchange chain among the participating incompatible pairs and to present a mathematical mechanism for this goal under the FCA approach. The share of the total compensation allocated to each incompatible pair in the chain under the FCA approach must be according to the characteristics to both kidneys being receives and donated to the chain.To describe the problem, Several authors in the literature have discussed the notion of fairness and equity in the allocation of divisible and indivisible goods ,42,43,44The main question of this article is how this compensation should be apportioned among incompatible pairs to have the minimum overall envy after the operations. To answer this question, this study presents a mathematical mechanism to determine the share of compensation paid by each participating pair under the FCA approach. Then, the results from this mechanism are compared with the apportionment results under the ECA approach. The following major assumptions are considered:The exchange chain is given in this study. To obtain this chain, one can employ approaches available in the literature ,45,46. TLiving donor’s cost apportionment is carried out to determine the share of each participating pair before the transplantation process.The chain pairs have been chosen from a predefined pool and do not choose to move to another chain . That isAll donor-recipient participants in the chain program are incompatible, and their orders in the chain have been defined based on the exchange program’s objective. Therefore, an incompatible pair cannot alter its corresponding pair for the kidney exchange ,25.It is assumed that all of the transplants in the chain would be performed successfully. In case of failure of the exchange chain due to last-minute failure of a transplant, the total share of subsequent incompatible pairs from the compensation is paid by the organization responsible for organ procurement and transplantation in the system.The characteristics of the kidney initiating the chain program are known. The amount of compensation that should be paid to the initial donor to cover his costs associated with the donation process is also given, and all participants are informed about and have agreed to this value.Although the last donor-recipient pair of the chain pays a share of the corresponding patient’s compensation, their donated kidney would be assigned to the first compatible patient on the waiting list.C is the total amount of compensation, n is the number of participating incompatible pairs in the chain and iC is the portion of compensation allocated to incompatible pair i. In the ECA approach, iC is easily calculated as follows:We compared two different approaches based on equality and equity to determine the share of the compensation for incompatible pairs. If However, the FCA approach is complicated. To develop this approach, we employ the Shapley value, one of the most prominent ways to allocate gains obtained by a set of players in coalitional cooperative games. The main idea of Shapley value is that members should receive payments or shares proportional to their marginal contributions in a cooperative game . AllocatiU is the utility that transplant i brings about the system, the FCA approach is defined as:iu is the utility donated by the ith incompatible pair to the chain and equivalents to the utility of the ith transplant, estimated based on the system administrator’s preferences as the entity responsible for matching donors and patients. In addition, i−u1 indicates the amount of utility received by incompatible pair i and, similarly, equals the utility of transplantation i−1. Accordingly, u0 indicates the utility of the initiating transplantation of the chain.Taking into account all mentioned factors, we calculate the odds of graft survival and determine patients’ share in providing compensation according to these probabilities. To this end, we employ the utility function to capture the nonlinear impact of graft-survival probability on the satisfaction of the pairs. Afterwards, compensation is apportioned among all pairs of the chain, considering their utility to the system. Given Note that each transplant has a utility value for the social planner, e.g., the IKF, aiming to maximize the number of patients receiving a kidney in the exchange program. Since Equation (2) takes the condition of both received and donated kidneys into account, it diminishes total envy between participants and consequently increases fairness.Utility theory has been proposed by Von Neumann and Morgenstern  to measuConversely, the decision maker prefers lower values of an attribute if the utility function is monotonically decreasing. With a non-monotonic utility function, the decision maker’s preferences concerning different attribute levels may increase or decrease . Risk avTo estimate the utility of a transplant, different characteristics of the recipient and the donor must be considered. Therefore, rather than directly estimating the utility function based on these attributes, we propose using these attributes to estimate the probability of graft survival and then defining each transplant’s utility based on its graft-survival probability. In this article, the likelihood of graft survival is estimated by a calculator based on the multivariate Cox regression survival analysis presented in . This caAs mentioned, converting the graft-survival probability to the transplant’s utility requires definition of a utility function. This study estimated this function using the standard gamble (SG) technique  on the dAs Equation (1) shows, the ECA approach apportions the identified compensation among all participants equally. However, the mechanism proposed under the FCA approach aims to apportion compensation among all participants regarding the characteristics of both kidneys they will receive and donate. These characteristics can be represented by the amount of utility provided for each participant. Due to the impacts of transplantation failure on the recipient’s quality of life and length of the waiting list, a kidney’s survival probability in the recipient’s body is usually considered the main factor in patient-utility estimation . AccordiU is the estimated utility of the transplant and T is the probability of graft survival 10 years after transplantation.Regarding the collected data, provided in the n is the number of incompatible pairs, i, that is the net utility, and be calculated as follows:Although the acquired utility function helps us estimate any transplantation utility, it could not be directly utilized to determine the share of an incompatible pair. Each pair grants an amount of utility to the chain and receives another amount from the chain. Therefore, the difference between the granted and the received utilities should be considered as an index to determine the share of compensation. To this end, let us assume that u and to keep the share of incompatible pairs non-negative, Equation (4) is normalized as follows:To avoid a negative value of Δi. Regarding Equation (5), an incompatible pair pays more portion of compensation if it has a higher value of normalized net utility. Therefore, each pair’s percentage of total compensation is calculated as follows:iC is the portion of the compensation allocated to incompatible pair i and C is the total amount of compensation that should be paid to the external donor. It is worth mentioning that if all pairs receive the same utility, the total normalized net utility would be zero. In this case, all pairs should pay an equal portion of the total compensation. Conversely, if the pairs receive variant normalized net utility, they would pay a different portion of the total compensation that could be obtained by Equation (6). Additionally, according to this Equation, the incompatible pair with the lowest Δu value does not pay any share of the compensation if its respective In this Equation To compare the results of cost apportionment under ECA and FCA approaches, first, we must evaluate the validity of our proposed cost-apportionment mechanism under the FCA approach. Therefore, To analyze the properties of the developed mechanism, we investigate two different scenarios of an operational kidney-exchange chain and discuss how the chain’s attribution mechanism and the amount of total compensation affect the compensation portion each participating incompatible pair should pay. The first scenario assumes four incompatible pairs  with different characteristics available in the kidney-exchange chain. A woman with a high BMI (body mass index) in the age range of 50–59 donates her kidney to the exchange chain. Besides, the total compensation for this donation is considered $5000.The latter scenario also includes four incompatible pairs similar to those in the former scenario. However, the external donor is a man with a healthy BMI and in the age range of <30. In addition, the living donor’s total cost in this scenario is set to $5500. Considering the data presented in As the results show, incompatible pair 2 is not supposed to pay any portion of the compensation since it has the minimum negative net utility in both scenarios. In addition, a significant part of the compensation is assigned to incompatible pair 3 due to the positive value of its net utility. Furthermore, the obtained result shows that finding a non-designated living donor who increases the graft-survival probability in the first transplantation certainly increases the share of the first incompatible pair and decreases the share of other participants, except for those pairs whose shares are zero.In this section, intending to assess the functionality of the mechanism under the FCA approach and compare its results with the apportionment scenario under the ECA approach, we implement 1000 rounds of simulations of kidney-exchange chains. Through this process, each pair’s share of the compensation and the outcome of each transplant operation 10 years after the procedure is determined. All of the characteristics of transplants in the chains are generated using uniform distributions within their parameter ranges specified by the KGSC . We perfAccordingly, these 1000 kidney-exchange chains include 8920 transplants in total, with random characteristics. According to our mechanism based on the FCA approach, the 10-year probability of graft survival and the utility value can be estimated for each of these transplants; Furthermore, The final results of the simulation process are presented in As previously mentioned, we aim to compare the results of cost apportionment based on two different approaches, ECA and FCA. In this regard, the functionality of these approaches must be assessed in the simulation results. As in In current renal-transplantation systems, living donors face financial burdens related to their act of donation, which can act as disincentives to donate. These financial burdens include transportation costs, lodging and parking costs, lost wages, etc. In many transplantation systems in other countries outside the U.S., such as Iran, organizations and governmental funds cannot cover these expenses. In these situations, compensation of the initiating living donors of kidney-exchange chains may potentially be paid by the participating pairs in the chains. We proposed the apportionment of the compensation of the initiating living donor in kidney-exchange chains between incompatible pairs of the chain based on the notion of equity, and compared its final results to those derived from the equality approach.To achieve this goal, this study developed a new mechanism employing the kidney chain of exchanges and utility function to apportion compensation among participating incompatible pairs based on the FCA approach. The proposed mechanism considers all donor and recipient characteristics in the chain and attempts to determine a compensation ratio according to the utility value of pairs. According to this mechanism, the amount of compensation allocated to incompatible pairs increases as they receive a better-matched kidney, and their share decreases as they donate a better-matched kidney.Furthermore, in comparison with dividing compensation equally between all participating pairs according to the ECA approach, the apportionment of total compensation between incompatible pairs by the proposed mechanism based on the FCA approach results in a decrease in total envy between the agents and an increase in fairness of the apportionment model. The reason for this is that by utilizing our mechanism, the apportioned share of compensation to agents with better bundles will be higher than that of other agents. Therefore, the amount of envy in their bundles will be lower. Thus, it can be concluded that by utilizing the FCA approach, we are moving towards more fairness and equity in the allocation of resources in organ-procurement systems, which results in more satisfaction among incompatible pairs.It is worth mentioning that in the proposed mechanism, each transplant’s utility is calculated solely based on the probability of graft survival post-transplantation. It does not investigate other factors, such as patient health status, affordability, etc. In addition, this FCA approach is not developed for the U.S.; instead, it is mainly intended for other countries that currently use an equality approach, such as Iran, and we do not endorse the use of this FCA approach in the U.S.The following are suggestions of topics that future research could investigate to improve the concept we presented in this research:Developing a multi-attribute utility function to capture other factors, such as affordability and survival probability, is another research line for future studies in the FCA approach. As mentioned, the current research assumes that the main factor determining utility is graft-survival probability. Although this factor is the most effective, other factors, such as affordability, the recipient’s health condition and PRA and the expected time for recipients to reach the top of the waiting, list may affect the recipient’s utility.Implementation of the FCA approach in the apportionment of compensation, assessing the potential increase in the number of kidney-exchange chains and the satisfaction level of participating incompatible pairs in these chains.In summary, we demonstrated that by utilizing the equitable approach, there is more fairness and equity in the allocation of resources in organ-procurement systems, which results in more satisfaction among incompatible pairs. Additional future prospective studies are needed to assess this proposed equitable approach for kidney-exchange chains in countries outside the U.S., such as Iran, that currently use an equality approach.


On top of this, we also explored corresponding training strategies for better grasp classification in real-time applications.Pattern recognition using surface Electromyography (sEMG) applied on prosthesis control has attracted much attention in these years. In most of the existing methods, the sEMG signal during the firmly grasped period is used for grasp classification because good performance can be achieved due to its relatively stable signal. However, using the only the firmly grasped period may cause a delay to control the prosthetic hand gestures. Regarding this issue, we explored how grasp classification accuracy changes during the reaching and grasping process, and identified the period that can leverage the grasp classification accuracy and the earlier grasp detection. We found that the grasp classification accuracy increased along the hand gradually grasping the object till firmly grasped, and there is a  Losing a hand is a tremendously physical trauma to any individual. Amputated individuals face a huge difficulty in performing daily activities independently , which cTo restore the functionality of hands in daily life and in work place, wearing prostheses is one of the necessary options for amputees. There are three types of prosthetic hands: cosmetic hand, body-power hand and Myoelectric hand ,5. AmongInterpretation on muscle signals is essential for the control of electric powered prosthetic hands, which requires machine learning algorithms to classify muscular electric signals into corresponding hand movement patterns. In most of the published papers, scientists use myoelectric signals recorded during firmly grasped periods for grasp classification, which yielded satisfactory classification outcomes ,9,10,11.When including muscle activities recorded from entire grasp period, the classification accuracy decreased. In Cognolato et al.’s report , the accsweet period. Once the sweet period is identified, we can develop a better classification strategy that can be used in the real-time environment.To solve this problem, developing a method to classify grasp pattern using sEMG data recorded in the earlier grasp period with a high accuracy is necessary. In this study, we investigate how grasp classification accuracy changes over the entire reaching and grasping process, and identify a period in early grasp phase that can achieve the best grasp classification outcome. We call this period as Specifically, we first apply and compare several processing methods for the feature extraction of the sEMG signals. Then, we conduct an experiment to find the sweet period that is suitable for early grasp classification with the best classification outcome. Finally, we will conduct another experiment to compare several common training and testing strategies to identify an effective strategy for better real-time grasp classification. We hypothesize that the muscle activities recorded in the early period of hand grasping can provide sufficient information to achieve the same or higher accuracy of grasp classification than other time periods with a reduced delay for prosthetic hand control.The data used in this study were from an open-source dataset collected by Cognolato et al. , where tTwelve sEMG sensors were placed on the forearm of each subject, producing twelve columns of sEMG data, respectively. Due to the hardware problem, no myoelectric data were received from electrode number eight during the acquisition of subject S024. Therefore, the sEMG data for this subject were recorded from eleven electrodes instead of twelve .Ten grasp gestures were performed in this data collection which were selected based on the hand taxonomies ,15,16,17In the data post-processing part, the abnormal samples were replaced with the precedent valid samples when filtering outliers . As therIn the feature extraction process, we first determined the suitable window size for deriving features . As showTo assure the recognition accuracy by using proper features, we tested eleven commonly used features, which were Standard Deviation (STD), Root Mean Square (RMS), Integrated EMG (IEMG), Mean Absolute Value (MAV), Waveform Length (WL), Log Detector (LOG), Simple Square Integral (SSI), Skewness (SKW), Kurtosis (KURT), Average Amplitude Change (AAC) and Difference Absolute Standard Deviation Value (DASDV) . We dropGradient boosting decision tree, such as XGBoost  and LighWe tuned the hyperparameters by using the training set of all the subjects and obtained the best results as follows: the learning rate is 0.1; no limit was set for the maximum depth; the number of estimators is 100; the number of leaves is 31; the remaining parameters are set to the default values.The Reaching Phase: starts from the hand lifting off, and ends by touching the object. During this phase, the hand is accelerated to a peak velocity and then is decelerated and brought to touch the target object. The hand usually opens to be configured to the target grasp gesture (pre-shape) .The Early Grasping Phase: begins at the moment when the hand initially contacts the object, and gradually closes the fingers until the hand starts to firmly grasp the object.The Firm Grasping Phase: the target object is firmly grasped and hand shape is maintained relatively steady.Normally, a typical reaching and grasping process can be divided into three phases ,25:The RWe segmented the Reaching, Early grasping, and Firm Grasping phases of each grasp gesture from each subject by observing corresponding videos frame by frame and calculated the average duration of each phase from all the observations. The judgment criteria for entering an Early Grasping Phase was the moment that the hand started to touch the target object, the judgement criteria for entering a Firm Grasping Phase was the moment that the target grasp gesture was completely formed and the hand started to keep relatively steady. According to the segmentation, Early Grasping Phase and Firm Grasping Phase started averagely 1020 ms and 1604 ms from the beginning of Reaching Phase, respectively. An example of grasp phases overlaid with sEMG signals during a full grasp trail is shown in We conducted two experiments, the first one aimed to analyse the grasp classification accuracy during the three grasping phases and find out the best position and length of sweet period, another was to find out the best training strategy.The grasp trials performed by the participants lasted approximately 4.5–5 s . We remoIn this study, each participant performed one grasp gesture four times (repetitions) which allowed us to split the sEMG data by repetitions to validate testing results. For all the cases in this study, we used three repetitions (75%) for training and one repetition (25%) for testing with leave-one-repetition-out cross-validation, which used one repetition data for testing and the rest three repetitions for training the model, and repeated this process four times to cover all repetitions for testing. To increase the reliability of the sEMG data set, there were three objects being grasped in each repetition with the same gesture as mentioned in the data collection section. In other words, there were 324,000 data samples (90 samples/grasp × 10 grasp gestures × 4 repetitions × 3 objects × 30 subjects) in the data set.From To find the optimal length of the sweet period, we designed different sliding windows with sizes of 300 ms, 400 ms, 500 ms, 600 ms, 700 ms, 800 ms, 900 ms and 1000 ms. The sliding window moved along with the time with step 50 ms, and in each move, it calculated and recorded the mean accuracy. We analyzed the records from the sliding window, and the results are given in From In the comparison experiment, we tested six strategies using different training and testing data, as shown in In cases 1–3, we used all the three grasp phases as training data and reduced the testing data size, from all three phases to only the firm grasping phase, then to the sweet period. The purpose of performing these three comparisons was to study which phase/period was the better choice for testing data when using all grasp phases as training data. Besides, to figure out which phase played a better role model training, we studied another five cases. For cases 4–5, we used Firm Grasping Phase for training and reduced the testing data size. In cases 6–7, we used a combined Phases for training and sweet period for testing. In case 8, we used the data in the sweet period for both training and testing. It is worth mentioning again, the cross-validation method used for all the cases was leave-one-repetition-out cross-validation which used one repetition data for testing and the rest three repetitions for training the model, and repeated this process four times to cover all repetitions for testing, such that all testing data was excluded from training the model. For example, in one testing repetition of case 8, the data from the sweet period of three repetitions were used for training the model and the rest one for testing. The results are presented in As shown in the Our hypothesis is supported by the results that there is a sweet period located in the Early Grasping Phase where sEMG signals can be used to achieve a similar or higher accuracy and lower delay of grasp classification than other time windows, which would help to improve the performance of robotic hand implementation in the real-life applications. This is important as the classifier can get the data much faster instead of waiting the muscle getting into the Firm Grasping Phase.We found that during the Reaching Phase, the mean accuracy of this phase is only about 63%. This is because, in this period, the subjects moved their hands to reach the object and start to perform the grasp gesture, keeping the muscle status changing. Therefore, the sEMG signals in this period fluctuate very much, making it difficult in decoding the sEMG signals, see When getting into the Early Grasping phase, the accuracy reaches approximately 85%, which is as high as that in the Firm Grasping phase. The possible reason for this is the hand has already fully formed into the target gesture during the Early Grasping phase. Although this formed gesture is slightly different to the final target gesture, it can provide sufficient information for the classification. Therefore, the accuracy reaches to a high level at the start of the Early Grasping phase. After the subject firmly grasps the object (getting into the Firm Grasping phase), the accuracy keeps stable at around 85% because the sEMG signals started to be stable, which also make the classification performance stable.Notice that the sEMG signal is more active in the Reaching and Early Grasping phases with high amplitude of the sEMG waveform as shown in Using all three grasp phases for training the model and only using sweet period for controlling is found to be the best strategy for Myoelectric prosthetic hand application in real-life condition, not only because the sweet period during Early Grasping phase is suitable for prosthesis control as discussed before, but also this strategy can also increase the recognition accuracy compared to other strategies. The possible reason of higher accuracy achieved by this strategy could be more variation data was included in the model training. From case 3 and 6 in the For case 5, the accuracy is only 60.80% when only using the Firm Grasping Phase for training because this period lost much information about gesture formation in Reaching and Early Grasping Phases. For case 8, the accuracy reaches 74.99% only using sweet period for training because this training data also lost the part of information about the gesture in the Reaching Phase and the Firm Grasping Phase. However, using all phases data for training and the sweet period data for testing achieved the best accuracy, which can be the common practice in real-life situations where training a model is not time-sensitive.In order to reduce the delay of myoprosthetic hand control in the real-life situation while maintaining a high recognition accuracy, we investigated the grasp classification performance during three grasping phases to identify the sweet period. We found that the sweet period located between 1.1 s and 1.4 s from the start of the hand grasping which happens in the Early Grasping phase before the hand is firmly grasped.Furthermore, we found using sEMG from all three grasping phases  for grasp classification model training achieved the best accuracy. Together with the identified sweet period for controlling, the grasp classification accuracy and the response speed of prosthetic hand can be balanced to achieve high performance.


This paper proposes a differential filtering method for the identification of modal parameters of bridges from unmanned aerial vehicle (UAV) measurement. The determination of the modal parameters of bridges is a key issue in bridge damage detection. Accelerometers and fixed cameras have disadvantages of deployment difficulty. Hence, the actual displacement of a bridge may be obtained by using the digital image correlation (DIC) technology from the images collected by a UAV. As drone movement introduces false displacement into the collected images, the homography transformation is commonly used to achieve geometric correction of the images and obtain the true displacement of the bridge. The homography transformation is not always applicable as it is based on at least four static reference points on the plane of target points. The proposed differential filtering method does not request any reference points and will greatly accelerate the identification of the modal parameters. The displacement of the points of interest is tracked by the DIC technology, and the obtained time history curves are processed by differential filtering. The filtered signals are input into the modal analysis system, and the basic modal parameters of the bridge model are obtained by the operational modal analysis (OMA) method. In this paper, the power spectral density (PSD) is used to identify the natural frequencies; the mode shapes are determined by the ratio of the PSD transmissibility (PSDT). The identification results of three types of signals are compared: UAV measurement with differential filtering, UAV measurement with homography transformation, and accelerometer-based measurement. It is found that the natural frequencies recognized by these three methods are almost the same. This paper demonstrates the feasibility of UAV-differential filtering method in obtaining the bridge modal parameters; the problems and challenges in UAV measurement are also discussed. Longterm use of bridges inevitably causes structural damage that may lead to bridge collapse accidents. It is necessary to carry out damage detection regularly. Vibration measurement is an important step in the field of vibration-based structural damage detection . The traAs a new type of bridge inspection tool, the UAV equipped with high-resolution cameras can hover in a predetermined position for image collection. The image data can be analyzed to evaluate the reliability, durability, and bearing capacity of bridges . MoreoveIn order to obtain the modal parameters of bridges exactly, numerous researchers have proposed methods to eliminate the false displacements caused by the UAV ego-motion. Yoon et al.  used triSince UAV movement is a random process, it is expected that the differential filtering method can eliminate this random component in the measured signals to get the correct modal parameters. Differential filtering as a signal processing method is often used for signal enhancement and recovery . The sigThis paper proposes a differential filtering method to remove the random UAV movement from the measured signals, through which the modal parameters of bridges can be obtained directly. A UAV is used to collect images of bridge vibrations, and then the DIC technology is used to track the points of interest to obtain their displacement time-history curves that contain the random UAV movement. The displacement time-history signals are processed by the differential filtering technology; the processed time-history signals are imported into the modal analysis system; the modal parameters are extracted by the OMA method. Finally, the feasibility of the differential filtering method in signal processing is verified by comparing with the homography-based and the accelerometer-based methods.The first step of this work is to process the UAV video frames by the DIC method; the second and third steps are to process the displacement data by using the homography-based method and differential filtering method, separately. Finally, the OMA method is used to estimate the modal parameters.The tracking principle of the DIC is shown in essed as ,37:(1)Cspi′=i-th row and j-th column of the homography matrix, The homography matrix, If there are more than four reference points, the least square method is used to solve the homography matrix.i-th  is usually used in the operational modal identification of the structure. In a multiple-degree-of-freedom system, the response transmissibility is defined as Tio(ω) :(8)Tio(ωi and o measured when the excitation force is applied at point p. From Equation (10), we have:The PSD transmissibility is expressed as:uillaume , the PSDon (FRF) . Fpω is r-th mode shape values at points o-th degree of freedom as a reference and the i-th degree of freedom being changed r-th modal shape can be obtained as follows:From Equation (12), the modal shape of the structure can be obtained as follows:Substituting Equation (9) into Equation (13):The process of using OMA to identify structural modal parameters is shown in The experiment is conducted in an outdoor environment. The experimental setup, instrument, plan, and goal are introduced in the following.The experimental model  is a 28-In order to improve the image resolution and tracking accuracy of the DIC method, the UAV shooting distance is shortened in this experiment. The UAV is used to take pictures at a distance of 3 m and records one half of the model.Digital camera  for recording model vibration;DJI’s quadrotor drones  with a high-resolution camera with a sampling frequency of 30 frames per second and a resolution of 1920 × 1080 pixels;A signal acquisition system for collecting signals ;A laptop computer connected to the acquisition system.The experimental equipment for modal analysis  includesThe displacement response is collected and processed by the dynamic acquisition system (JM3841), and then the structural modal parameters (frequencies and mode shapes) are obtained from the processed PSD and CPSD curves.The experiments are designed to verify the effectiveness of the proposed differential filtering method in obtaining the modal parameters from UAV measurements. The experimental layout is shown in As shown in (a)Verifying the correction accuracy of the UAV results by comparing them with fixed cameras. The image sequence of the UAV is corrected by homography transformation to obtain the true displacement time-history signal, which is imported into the dynamic acquisition software with the time-history signal of the fixed camera to obtain the modal parameters. The results are compared with those of the fixed camera to demonstrate the feasibility of UAVs in actual vibration measurement.(b)Verifying the accuracy of the differential filtering method by comparing with homography-based correction results. The uncorrected time-history signals of UAV measurements are processed by the proposed differential filtering, and the processed results are input into the dynamic acquisition software to obtain the modal parameters, which are compared with those identified from the other two methods: accelerometer measurements and homography-based correction of UAV images.The main goals of this experiment include the following:The experimental results are presented in three parts. The first part compares the measurement results of the UAV and the fixed camera. The second part describes the different processing effects between the differential filtering and the homography correction. The last part compares the modal parameters extracted by three methods: differential filtering, homography correction, and accelerometer measurement.The largest vibration amplitude of the bridge model is at the middle of the span, thus Node 15 is selected as the target point for comparative study.The displacement (corrected and uncorrected) of the target point is shown in As shown in The time-history curve of the target point is processed with second-order differential filtering and homography transformation, and the results are shown in The results of homography transformation and differential filtering show the same free vibration attenuation characteristics by comparing the two curves in The PSD curves of the original signal and the corrected signal of UAV measurements are shown in The original signal and corrected signal of UAV measurement are processed by the second-order differential filtering; the modal parameters are shown in In addition, the first-order mode shapes obtained by differential filtering, geometric correction, and accelerometer methods are shown in In this paper, the UAV images processed by the DIC and the obtained displacement signals are either corrected by the homography transformation or the differential filtering method. The OMA is carried out to identify the corresponding modal parameters, and the feasibility of the differential filtering replacing the UAV correction in identifying modal parameters is proved.(1)Under the same experimental conditions, UAVs can replace fixed cameras to accomplish data acquisition. The real-time history signals can be obtained after the homography transformation. Compared with accelerometer measurement, the DIC method is non-contact and full-field. More target points can be selected for measurement to improve the identification accuracy of mode shapes. Combination of the DIC technology with UAV measurement can greatly improve the efficiency of modal identification of real bridges.(2)Differential filtering is used to remove the zero drift and signal noise in UAV signals. Differential filtering can replace geometric correction for data processing and the modal parameters can be directly identified without obtaining the real structural displacement. Hence, differential filtering can greatly simplify modal identification from UAV measurement.The following conclusions can be drawn from the above work:In conclusion, the differential filtering method proposed in this paper is simple to operate and applicable to modal identification in bridge engineering. Compared with the homography-based method, the proposed method does not require either fixed reference points or image geometric correction. By directly differentiating the collected bridge vibration data twice, the zero-point drift of the PSD curve caused by the drone motion is filtered out, and the high-frequency part of the signal is also amplified, which is beneficial to the identification of higher-order vibration frequencies. Eventually, the natural frequencies and mode shapes can be obtained directly from the uncorrected displacement data that contains UAV motion. This greatly improves the efficiency of bridge vibration measurement using UAVs. With the further development of UAV technology and image processing algorithms, vibration measurement technology based on UAVs will play a more important role in dynamic analysis and damage identification of bridges.


Plasmodium falciparum has long been rejected, several recent works pose hypotheses and provide direct and indirect evidence of the existence of mechanisms similar to RNA interference in this organism. In particular, the possibility of regulation of P. falciparum gene expression through human microRNAs is of great importance both for fundamental biology and for medicine. In the present work we address the problem of possibility of the existence in the P. falciparum genome of the nucleotide sequences such that mRNAs transcribed from genes containing these sequences could form duplexes with human microRNAs. Using bioinformatics methods we have analysed genomes of 15 P. falciparum isolates for sequences homological to these microRNAs.Malaria is a disease annually causing over 400,000 deaths. Deep understanding of molecular and genetic processes underlying its life cycle and pathogenicity is required to efficiently resist it. RNA interference is a mechanism of the gene expression regulation typical for a wide variety of species. Even though the existence of this phenomenon in The analysis has demonstrated the existence of a vast number of genes that could potentially be regulated by the human microRNAs in the plasmodial genome.P. falciparum malaria. The majority of homological intervals occur in genes encoding cell adhesion proteins.Despite the fact that the numbers of homological intervals vary significantly between isolates, the hsa-miR-451a and hsa-miR-223-3p microRNAs are expected to make the most notable contribution to the pathogenesis of  RNA interference is one of the most prominent breakthroughs in molecular genetics of the late twentieth century. In the broad sense of the term, the essence of this phenomenon lies in eukaryotic gene expression regulation  by small non-coding RNAs (ncRNAs). Initially the use of the term was limited to posttranscripional gene silencing (PTGS) mediated by small non-coding RNAs of a certain class called small interfering RNAs (siRNAs). In this case, gene silencing occurs due to the formation of complementary bonds between a siRNA and a target mRNA either leading to the endonuclease clevage of the target RNA or directly impeding its translation. Further research has revealed the existence of several other types of small ncRNAs having similar mechanisms of functioning, as well as other mechanisms of gene expression regulation mediated by small non-coding RNAs. To date, the most extensively studied class of small non-coding RNAs participating in such interactions is microRNA, which are double-stranded RNA molecules typically from 19 to 25 nucleotides in length. Unlike siRNAs, microRNAs are endogenous and can utilise various mechanisms to regulate gene expression: besides the endonuclease cleavage of the target mRNAs, a microRNA can cause translation termination during initiation or elongation. MicroRNA and siRNA also differ in the anticipated function: microRNAs are considered to alter gene expression, stabilise mRNA and protein level and repress stochastic fluctuations of the gene expression level between different cells while siRNAs predominantly target exogenous nucleic acids such as mobile genetic elements and viral mRNA , e.g. nucleotides [It is worth mentioning that a microRNA contains the so-called seed region, which, as a rule, consists of nucleotides lying in the , 8 interleotides , 20 in tP. falciparum isolates  and 7 microRNAs   separately due to their importance in the pathogenesis of malaria, as well as all genes encoding proteins and RNA in general.One of the most important criteria in the assessment of the potential importance of a microRNA in P. falciparum isolates to interact with the human microRNAs was analysed in more detail; the results of this analysis are summarised in Tables P. falciparum isolates.The number of homologous intervals with the same microRNA significantly differs between various In most cases, the majority of homologous intervals are located within genes encoding PfEMP1. The number of homologous intervals with RIFIN genes is significantly lower and close to zero in case of STEVOR genes. In none of the cases under consideration the number of homologous intervals with PfEMP1 pseudogenes exceeded those with genes encoding the other cell adhesion proteins.The potential ability of different P. falciparum TG01 isolate genome is higher by an order of magnitude than the one in the P. falciparum 7G8 isolate.The numbers of homologous intervals with hsa-miR-451a are maximal for all isolates; these values are reflected in the last column. Among the analysed genes encoding cell adhesion proteins, as indicated by columns 3–6, the majority of potential interactions are expected to happen with mRNAs encoding the PfEMP1 protein, and hence this protein is expected to be particularly affected by the RNA interference-like mechanism. With minor exceptions, the numbers representing potential interactions with specific cell adhesion proteins for hsa-miR-451a are higher in comparison with all the other microRNAs under consideration. Interestingly, the total number of homologous intervals with this microRNA differs almost twice between the isolates; the separate quantities calculated for specific genes encoding cell adhesion proteins differ even more significantly: the proportion of homologous intervals with PfEMP1 genes within the P. falciparum genes might be regulated by human microRNAs using a non-canonical mechanism similar to RNA interference. We have found that the genome of P. falciparum contains genes encoding mRNA potentially capable of forming duplexes with human microRNAs. Taking into consideration the previously demonstrated fact of transport of the RISC elements into the organism of the parasite, this result may indicate the possibility of RNA interference in P. falciparum and regulation of gene expression through human microRNAs.The bioinformatics research indicates that the expression of P. falciparum gene suppression is completely different and is based on the formation of covalent bonds between imported human microRNAs and 5′ ends of P. falciparum mRNAs similar to trans-splicing. It is worth mentioning that we have found no other works that would support this hypothesis. Thus, the pathway according to which human microRNA enter the parasite and form hydrogen bonds with complementary sequences in plasmodial mRNAs or non-coding RNAs seems more feasible. However, the authors also consider miR-451a as the major factor of P. falciparum gene expression deregulation. Besides that, the novelty of this study is provided by the fact that we have found no works in which the researchers would specifically emphasise the role of the cell adhesion proteins of P. falciparum as a potential target for human microRNAs.The topic to which this work is devoted is not quite well covered in the literature. To our knowledge, only two similar works exist: one is by LaMonte et al.  and the P. falciparum. This fact allows us to consider this phenomenon to be an antiparasitic protective mechanism of the human. The significant numerical superiority of the number of binding sites for the hsa-miR-451a and hsa-miR-223-3p microRNAs that was revealed as a result of the analysis correlates with the increase in the level of these microRNAs in patients with malaria described in the literature. Similarly, the observed patterns in the number of binding sites in mRNAs encoding adhesion proteins correspond to the fact that sequestration of red blood cells and rosette formation can be mediated by the PfEMP1, RIFIN, and STEVOR proteins, with PfEMP1 playing the leading role in these processes. In addition, the analysis of the genomes of various P. falciparum isolates has shown significant differences in the number of possible target mRNAs for human microRNAs, which may serve as a diagnostic criterion for determining the strain of P. falciparum and for prediction of the further course of malaria.As a result of the analysis, it has been found that a significant proportion (up to 1/3) of all mRNAs with which the investigated human microRNAs can form complementary bonds are mRNAs encoding cell adhesion proteins of Plasmodium genus and to determine the possible effect of microRNA of the macroorganism on the course of other forms of malaria.The main direction of further work is experimental verification of the aforementioned hypotheses using molecular methods, namely, microRNA sequencing to determine microRNA profiles in different cases and quantitative PCR to explore relationships between the human microRNA and plasmodial RNA levels. Besides, it is essential to research the existence of similar mechanisms in other species belonging to the


Based on the perspective of complex system management of forest biomass power generation (FBPG) supply chain, this paper explores a new way to reduce the operation cost of forest biomass raw materials supply chain and improve the operation efficiency of forest biomass supply chain in China. Firstly, the supply chain model of FBPG is summarized through the survey data, and the existing problems are found. Then, the behavior strategies among farmers, middlemen, and enterprises are analyzed, and the data that cannot be obtained in the model are estimated by using statistical methods. Finally, the complex supply chain system is simulated by computer. Through setting different forestry policies, this paper compares and analyzes the profit of the supply chain and puts forward policy suggestions to promote the development of the FBPG industry in China. In this paper, the actual situation, principles of statistics, and system simulation are effectively combined to make the behavior rules of various stakeholders fit the reality, and the research conclusions are more practical. With the development of society, the importance of the ecological environment has become increasingly prominent. As a renewable and clean energy industry, biomass energy industry is of great significance to improve environmental quality and develop circular economy. Forest biomass power generation (FBPG) industry is an important part of biomass energy industry. It can generate economic benefits by making rational use of forestry resources and bring substantial ecological benefits by reducing pollutant emissions to protect the natural environment. Especially for the northwest area with poor natural conditions in China, the energy development of tending residues such as pruning shrubs can improve the income level of local farmers and the local natural environment.Although the utilization of forest biomass energy is essential, China's FBPG industry is still in the initial stage of development, and there are many problems in actual development. For example, farmers lack the will to collect, so it is difficult to collect forest biomass raw materials on a large scale. In addition, the cost of raw materials remains high, and the degree of marketization is low. Therefore, from the perspective of the complex system of forest biomass raw materials supply chain, it is of great significance to mobilize the enthusiasm of farmers to collect and reduce the cost of raw materials by optimizing the policy combination so as to maximize the overall profit of the supply chain and ensure the sustainable and stable operation of biomass power generation enterprises.This paper combines the supply chain of FBPG with computer simulation technology. Firstly, the paper models the complex supply chain system composed of farmers, middlemen, and biomass power generation enterprises and constructs a multiagent raw materials supply chain simulation model. Then, the paper puts forward the optimal combination scheme and policy suggestions for the development of the FBPG industry through simulating the simulation results under different parameters, which has important practical significance for expanding the scale of the FBPG industry in China.Forest biomass refers to the organic matter formed by photosynthesis of woody plants such as forest trees. Forest biomass energy is the energy stored in forest biomass after conversion; that is, the energy can be used for power generation or heating through direct combustion or modern conversion technologies , 2. ForeThe development of the biomass energy industry still faces problems such as difficult raw materials collection, low equipment utilization, and high operation and maintenance costs , 5. By 2The simulation modeling method based on multiagent started in the late 1990s. This method adopts bottom-up modeling thought and emphasizes the authenticity of microindividuals during modeling. The model establishes the relationship between agents through the message mechanism and then forms the macroframework of the simulation system. Many scholars have applied multiagent simulation technology to the supply chain of forestry, agricultural products, and other fields. For example, Hanafizadeh and Sherkat  used NetBecause of the different characteristics of supply chains, there are also differences in agent behavior rules. The multiagent modeling of the FBPG supply chain is more considered from the perspective of raw materials supply. According to the research results, farmers, middlemen, and enterprises can be abstracted as agents with independent decision-making, learning, and memory ability. There are obvious differences in the decision-making rules of agents, the interaction rules between agents and between agents, and the external environment. The use of multiagent simulation technology shows obvious advantages. The behavior rules of simulation agents are designed according to the actual behavior of individuals. Through the interaction of microagents, various emergent behaviors and self-organization phenomena in the system can be effectively explored .In conclusion, the forest biomass energy industry has extensive development space. The existing problems are mainly backward technology, lagging policy, insufficient supply of raw materials, and high production cost. Therefore, it is necessary to study the supply chain of forest biomass energy raw materials from the perspective of microagents. Policy factor greatly impacts biomass power generation industry, which can promote industrial development through economic policy adjustment. In addition, although the multiagent simulation method is not widely used in the forest biomass energy supply chain, there have been many studies in the field of forestry and agriculture. Therefore, it is reasonable to summarize the industrial policy suggestions through a series of simulation experiments.As a biomass enterprise, the power generation product cannot be saved.Raw materials have a wide production area and large output, but the collection has periodicity and is greatly affected by factors such as environment and season.There are many alternative uses of raw materials, resulting in large supply fluctuation.Raw materials are susceptible to moisture and decay, with low weight and value density. The cost of transportation and storage is high.The raw materials supply of enterprise is generally subject to many farmers and middlemen. The enterprise does not occupy a dominant position.The characteristics of FBPG supply chain are as follows:It can be seen that FBPG supply chain is essentially different from the conventional production supply chain. The latter usually only focuses on the uncertainty of the consumption market, while the former pays more attention to the uncertainty of upstream raw materials supply.In addition, compared with biomass raw materials such as straw, the geographical distribution of forest biomass raw materials is more special, the collection quantity is more uncertain, and the transportation cost is more expensive. Therefore, the upstream of FBPG supply chain is relatively complex, and the supply is unstable. By signing contracts and expanding the scope of purchase, the cooperative relationship between various agents can be stabilized. When establishing the simulation model, seasonal and other random factors will be set to reflect supply uncertainty.The first-hand data used in this paper was obtained by issuing questionnaires in Wushen Banner and Hangjin Banner of Inner Mongolia Autonomous Region, and Zhongwei City of Ningxia Hui Autonomous Region, as well as in-depth interviews with enterprises' leaders. The survey covers the basic information and raw materials purchase information of enterprises. In this survey, 5 enterprises were visited, and 127 questionnaires of farmers related to biomass energy were completed. Fifty-four farmers have sold raw materials in two ways .In the upstream supply chain of FBPG, there are mainly two kinds of raw materials transportation modes. One is that forest farmers directly sell to FBPG enterprises; the other is that forest farmers sell to middlemen and then sell to enterprises by middlemen. The downstream supply chain is relatively simple. The only customer is the State Grid Corporation of China (SGCC). The whole FBPG supply chain system can be shown in The upstream supply chain of FBPG enterprises in China is mainly two-level or three-level supply chain: (1) two-level supply chain: farmers/upstream companies/enterprises -power generation enterprises; (2) three-level supply chain: farmers-middlemen-power generation enterprises. Specifically, power generation enterprises mainly obtain raw materials through four modes: first, power generation enterprises independently cultivate economic forests as raw materials for power generation; second, enterprises cooperate with upstream companies to obtain raw materials, which are generally molding fuel enterprises; third, enterprises purchase crops or forest residues from farmers; fourth, enterprises purchase raw materials from middlemen. These middlemen are mainly individual farmers. Due to the market economy, they have spontaneously become a hub connecting upstream and downstream raw materials.The choice of raw materials supply mode depends on many factors such as business plan, capital status, geographical location, and other factors. Enterprises often choose mixed modes. Mode 1 belongs to internal production of enterprises and has a low degree of application. Mode 2 is interest cooperation among enterprises. Mode 3 and mode 4 are transactions between individual farmers and enterprises. Therefore, this paper mainly studies mode 3 and mode 4.The downstream supply chain of FBPG is a two-level supply chain: power generation enterprises-SGCC. In addition to a few enterprises using the advantage of biomass power generation to increase sideline income, SGCC is the only downstream customer in the sale chain of the whole industry. Therefore, the formulation of policies on FBPG largely determines the survival and development of power generation enterprises.At present, the feed-in tariff standard of biomass energy in China is 0.75 yuan/kWh. The feed-in tariff is the price of power commodity delivered to SGCC by power production enterprises. As China has formulated the priority scheduling policy, the sale of biomass power generation will be guaranteed. Moreover, according to the Renewable Energy Law, biomass power is preferentially connected to the grid and does not participate in peak regulation. Therefore, these policies reduce the impact of changes in electricity consumption of end customers on biomass power generation industry and ensure the stability of sale of biomass power generation enterprises.Salix psammophila) pruned from the roots as raw materials.This part establishes the three-level supply chain simulation model consisting of farmers, middlemen, and biomass power generation enterprises and uses NetLogo software for simulation. The role of the government appears in the form of subsidy parameters in the simulation system. The behaviors of farmers and middlemen adopt the “economic man” hypothesis. Middlemen will adjust their purchase scope according to the price of enterprise to maximize their profit. The simulation system takes enterprise as the core node of the whole supply chain to simulate the optimal purchase price and government subsidy when the enterprise reaches production capacity. The parameters and some processes of the model are mainly based on the relevant data of the Maowusu biomass thermal power plant in Erdos, Inner Mongolia. The enterprise takes the branches of sandy shrubs  How much purchase price can make the biomass power generation enterprise reach production capacity and obtain the maximum ecological benefits. (2) How much government subsidy can ensure that the enterprise does not lose money at the purchase price of reaching production capacity. (3) What policy can be implemented to improve the overall efficiency of the supply chain.2Salix psammophila can produce about 1t branches  yuan.When Q/2.5] means to take the smallest integer larger than itself.[2) can be calculated.Therefore, the transportation cost of the farmer (FC(5)The profit of farmer from selling raw materials to the enterprise is(6)The profit of farmer from selling raw materials to the middleman is(7)W1 and W2 to choose to prune or not, and whether to sell to the middleman or sell to enterprise. Calculate the quantity of raw materials actually transported to the enterprise (Qfe) and the quantity of raw materials actually transported to the middleman (Qfm) in each cycle.The farmer compares Farmers aim to maximize their profit and choose a reasonable sale object. Farmers' profit is sale income plus government subsidy and minus all costs. Farmers need to pay the collection cost of collecting biomass raw materials; the income of farmers mainly comes from biomass raw materials in their woodland. If it is sold directly to the enterprise, it also needs to pay the transportation cost. The main influencing factors of biomass raw materials transportation cost include vehicle technical performance, vehicle operating cost, characteristics of crops, collection mode, and radius . BecauseThe specific behavior rules of farmer are shown in Salix psammophila matures in about three years, and the more it is cut, the more lusher it is. If the grown branches are not cut off, it will become dead branches in less than seven years. Because the government has public welfare forest subsidy for energy forest, once Salix psammophila dies, farmers will not be able to obtain public welfare forest subsidy, which will cause great losses to farmers. Therefore, the system assumes that farmers must choose to prune in the cycle, and the frequency of pruning is set to one time every three years. Moreover, the purchase scope of the middleman may not cover all farmers, so the farmer needs to judge whether he/she is within the purchase scope of the nearest middleman in advance so as to make the next decision of choosing to prune or not and selecting sale object.It should be noticed that Middlemen also aim to maximize their profit and hope to acquire and sell as many raw materials as possible. Middlemen are responsible for the initial processing and transportation of raw materials in the supply chain. The transportation route consists of two parts: one is that the middleman purchases from the farmer and then transports raw materials to the processing point (the location of the middleman), and the other is that the middleman transports raw materials from the processing point to the biomass power generation enterprise. Middleman decides the current purchase scope based on the current purchase price of the enterprise.When middleman purchases raw materials from retail farmers, the unit transportation cost is 0.25 yuan/ton·km .Because the middleman cannot accurately estimate the purchase quantity before determining the purchase scope, the unit transportation cost transported to the enterprise is temporarily calculated as full load so as to calculate the purchase radius R of the middleman.The estimated unit transportation cost of transporting raw materials to the enterprise is 0.067 yuan/ton·km .R of the middleman should base on the economy of cost. According to the calculation method of purchase radius in reference [The purchase radius eference , the uniAccording to the questionnaires, there are two main types of vehicles used by middlemen, as shown in (1)The purchase quantity of the middleman is the sum of the quantity of raw materials within the purchase scope:(2)1=MCost × Qm.The primary processing cost of the middleman is MC(3)The actual transportation cost of the middleman is(4)The profit of middleman isThe maximum purchase radius of the middleman isThe specific behavior rules of middleman are shown in The enterprise plays a leading role in the whole supply chain. The change of enterprise's purchase price will have an impact on the purchase scope of middlemen and farmers' willingness to sell. The initial price of the enterprise is set according to the current market price. If the production capacity is not reached, the purchase price of the enterprise in the next cycle will increase by 5 yuan/ton. If output exceeds demand, the price in the next cycle will be reduced by 5 yuan/ton to reach an equilibrium state.Price change function: EPri=EPri+5Qe=Qm+QfeTotal quantity of raw materials purchased by the enterprise: q=800 × QePower generation of the enterprise: 1=0.292 × qPower generation cost: EC2=EPri × QePurchase cost of the enterprise: ECW4=0.9 × Price × q − EC1 − EC2The profit of the enterprise: Some formulas are calculated as follows:In , 0.9 meaThe initial parameters used in the simulation system come from the survey data of farmers in many towns in Inner Mongolia and Ningxia. Except for unit pruning subsidy, other parameters are assigned in the form of sliding strip. The initial values of number of farmers, number of middlemen, middlemen purchase price, and feed-in tariff are all taken from the survey data as described in First, input the initial parameters into the system, as shown in n = 0), the light green area is the woodland within three years after pruning (n < 3), and the dark green area represents the woodland that can be used for pruning (3 ≤ n ≤ 5). Farmers are represented by small triangles, middlemen are represented by white squares, and the enterprise is represented by a red dot in the center. With the dynamic change of cycle, the interface can visually show the change of pruning and the transportation of raw materials.After inputting the initial parameters, design the view interface of the FBPG raw materials supply chain network, as shown in Under the setting conditions in Under the setting conditions, the profit of enterprise is negative. Similarly, export the relevant data of enterprise's profit, as shown in Therefore, continue to adjust the feed-in tariff to study when enterprise generates profit. When the feed-in tariff reaches 0.85 yuan/kWh, the power generation profit of the enterprise is still negative, with a loss of about 3 million yuan. Continue to gradually increase the feed-in tariff by 0.01 yuan until 0.95 yuan/kWh, and the enterprise can achieve profitability under the condition of meeting the raw materials demand, as shown in It is not difficult to find that the simulation result is basically consistent with the survey data of existing policy. At present, the purchase price of forest biomass raw materials is 400 yuan per ton, and the enterprise can only purchase 80000∼90000 tons of raw materials. In the survey, it is found that most biomass power generation enterprises are in a state of loss at the price of 0.75 yuan/kWh. Therefore, it can be verified that the model construction is basically reasonable.The previous section has verified the rationality of the model. Therefore, adjust the parameters from the perspective of supply chain, internal agent, and external environment, and further discuss the influence of parameter change on supply chain. Several comparative experiments are carried out based on the initial parameters.β) is very important. In the above initial environment, compare the profit of middleman, enterprise, and farmer, as shown in The policy subsidy sharing contract can help the whole supply chain achieve coordination . The supt = 7 (not reaching equilibrium) and t = 17 (reaching equilibrium), the two nodes' raw materials purchase price of the enterprise is different, which are 380 yuan per ton and 420 yuan per ton, respectively. Compare the profit of each agent and the whole of the supply chain under the two nodes, and sort out the relevant data of the nodes in When the feed-in tariff remains unchanged (price = 0.95), two periodic nodes are selected, which are the node that does not reach equilibrium and the node that reaches equilibrium. For example, at the two nodes of t) is 0.673 yuan/kWh (0.95–0.277), which is equivalent to 538.5 yuan/ton of forest biomass raw materials. At this time, the purchase price is 420 yuan/ton, and the subsidy coefficient (β) can be calculated as 0.074.When the purchase price of the enterprise increases, the overall profit of the supply chain increases significantly, which verifies the rationality of the experiment. In this experiment, the government subsidy  in the region has a great impact on the whole supply chain. Therefore, when selecting the site, it is necessary for enterprises to investigate the local forest biomass energy potential and choose the area with rich resources as the power generation address. The number of middlemen will also have a certain impact on the raw materials purchase of enterprises. If the number of middlemen in the region is too small, it will also increase the difficulty for enterprises to acquire raw materials. In particular, it is difficult to acquire raw materials from farmers in remote areas and small areas.Combined with the actual operation of the current enterprises in China, the current feed-in tariff of 0.75 yuan per kWh (including subsidy) is low for biomass power generation enterprises, and most enterprises are facing the crisis of bankruptcy. The survey also found that 69 farmers believe that the current purchase price of raw materials is unreasonable. The simulation results show that when the feed-in tariff is increased to about 0.95∼1.0 yuan per kWh, the biomass power generation enterprises will not suffer losses when reaching the production capacity. At the same time, the purchase price of the enterprises needs to be improved. Under the current purchase price, the supply of raw materials is insufficient. It is more appropriate that the purchase price of raw materials should increase about 25 yuan at the current level of 400 yuan per ton.Unit pruning cost has a great impact on the whole supply chain. The increase of pruning cost will lead enterprises to reach the production capacity at a higher purchase price. At the same time, the feed-in tariff that meets the profitable conditions of enterprises will also increase. Therefore, combined with the relevant policies of energy subsidy in the western region of China, the government can adopt appropriate subsidy for purchasing agricultural machinery to realize large-scale mechanized collection and greatly reduce the cost of artificial pruning. The government gives farmers a pruning subsidy, which can also promote some farmers to participate in pruning and increase the supply of raw materials.When selecting the site, biomass power generation enterprises need to take the external environment factors into account to ensure that the number of local farmers can provide enough forest biomass raw materials. In addition, the enterprises should establish a long-term and stable partnership with middlemen, reasonably plan the number of middlemen, and ensure a stable supply of raw materials.The simulation experiment is carried out by adjusting the parameter value, and the results are summarized as follows:FBPG industry is of great significance to protect the ecological environment and promote the increase of farmers' income in the western region of China. Research and survey found that the current bottleneck of industrial development in China is mainly due to the insufficient supply of raw materials and serious losses of enterprises. In order to solve this problem, this paper discusses the coordination of the FBPG supply chain on the premise of uncertain supply. This is a supplement to a subdivided field of straw biomass power generation supply chain research. At the same time, the combination of empirical research and case analysis makes up for the defect of excessive parameter value deviation in the simulation processes and enriches the research content of multiagent simulation of the supply chain. The conclusions of this paper are as follows.Firstly, it is relatively difficult to collect forest biomass raw materials in China, which has a great relationship with the terrain. Farmers' collection cost is high, and they generally believe that the purchase price of enterprises is low. Because the labor income level has been increasing in recent years, this leads to the low willingness of farmers to collect and sell raw materials. In addition, forest biomass raw materials also have many other values besides being sold to enterprises, such as covering sand layer (sand-prevention) and self-use as an alternative fuel. There are many methods to sell biomass raw materials collected by farmers. The choice of farmers depends on which method can obtain the greatest profit. Therefore, through reasonably increasing the purchase price and giving subsidy for purchasing agricultural machinery, the participation of forest farmers can be improved. It is conducive to the stable supply of raw materials and helps the sustainable and stable development of enterprises.Secondly, middlemen are an important and stable source for FBPG enterprises to purchase raw materials. At present, the government only provides a feed-in tariff subsidy for biomass power generation enterprises. If the enterprise transfers part of the subsidy to middlemen, the purchase quantity of middlemen will increase, and the profit of the enterprise will also increase. Therefore, enterprises can improve the supply enthusiasm of middlemen by means of increasing purchase price and ensure that the raw materials of FBPG enterprises meet the production capacity demand as much as possible. It also avoids the loss of stock shortage.Finally, at the current stage, if the enterprise is expected to meet the production capacity demand, the purchase price of 425 yuan per ton is reasonable. In this case, the feed-in tariff can be increased to about 0.95 yuan per kWh to ensure the sustainable operation of biomass power generation enterprises. In addition, reducing the power generation operation cost of enterprises, promoting the use of brush cutters, reducing labor cost, and providing pruning subsidy can also promote the overall efficiency of the supply chain.Although this paper simulates the reality of the FBPG supply chain in China as much as possible, there are still some details to be further considered due to the complexity of reality. For example, there is a time gap  in the issuance of policy subsidy, which may lead to insufficient funds for enterprises to purchase biomass raw materials in that year, and many farmers think that it is difficult to prune, which may lead to a lack of labor. So middlemen need to hire labor from other provinces in China, increasing the cost of pruning.The simulation model is only applicable to the forest biomass raw materials supply chain in the western region of China, which can be improved and optimized to make it applicable to other regions.Continue to enrich the behavior rules of agents, such as the behavior rules of enterprises. The current setting of enterprise is that price is set on a uniform basis. As a result, farmers close to the enterprise can get rich income, while farmers far away can get less income. So the hierarchical pricing strategy can be further considered. There are different purchase prices for farmers at different distances, which can reduce the cost of enterprises.The distribution of farmers, middlemen, and enterprise in the model is different from reality, so a regional map can be introduced to optimize the simulation effect.Further discuss the problem of labor shortage in the western region of China.These complex situations may become important factors hindering the development of biomass enterprises in China. Therefore, the prospects are put forward in the follow-up research: