Research on calibration method of microscopic parameters of siltstone based on gray theory.

When the Linear Parallel Bond Model (PBM) in Particle Flow Code is used to simulate intact rocks, a basic problem is how to determine the microscopic parameters that control the macroscopic properties of the modeled rocks. After simplifying the microscopic parameters of the PBM model, this study proposes a new method of inverse performance of the regression equations of the macroscopic parameters by the gray absolute correlation combined with regression analysis, which solves the drawbacks of the current manual trial parameter calibration method to a certain extent. When this method is applied to the calibration of the microscopic parameters of the siltstone, the numerical simulation results produce good agreement between the results derived from the finite element software (ABAQUS) both in terms of macroscopic parameters and damage forms.

Trajectory optimisation with musculoskeletal integration features for fracture reduction orthopaedic robot.

BACKGROUND: Human body is an integrated system of bones and muscles. To date, there are insufficient studies on the effect of muscles on the trajectory planning of orthopaedic robot. To this end, based on a Stewart-Gough platform (6-UPU) fracture reduction orthopaedic robot, a musculoskeletal trajectory optimisation method was constructed for the interference of soft tissue during the reduction process. METHODS: Firstly, pose description of the fracture reduction orthopaedic robot was introduced, and its working space was analysed. Secondly, an improved Hill muscle theory was used to construct the musculoskeletal system, and finite element analysis (FEA) was carried out. Thirdly, particle swarm optimisation (PSO) with variable weights was imported, and fracture reduction trajectory planning was obtained by quintic polynomial in the workspace. Then mathematical model for trajectory optimisation was presented, and targets of musculoskeletal optimisation were extracted, which include muscle energy consumption, robot-assisted repositioning time and trajectory length. In this sense, musculoskeletal integration trajectory optimisation method was put forward. Finally, comparative optimisation simulation with skeleton only and bone and muscle together were tested, and safety experiment with musculoskeletal integration was conducted. RESULTS: A cone shape workspace was got, whose range can be defined as 635.14 mm on the X axis, 720 mm on the Y axis, and 240 mm on the Z axis, respectively. Besides, different FEA displacements revealed the effect of bone and muscle on the movement of the robot. Moreover, the optimal results with and without muscle had showed different movement time: the former consumed about 27 s, but the latter spent about 25 s. Additionally, the speed and acceleration of the drive rods can be obtained from zero to zero during the reset. CONCLUSIONS: The results show that the optimised trajectory obtained with this method is safe and reliable. Furthermore, the presence of muscle has great influence on the trajectory of robot, which could prolong the reduction time so as to prevent the occurrence of uneven soft and hard traction rate problem. This paper could be helpful for the future trajectory planning study of fracture reduction orthopaedic robot.

Hill-based musculoskeletal model for a fracture reduction robot.

BACKGROUND: The introduction of fracture reduction robot can solve the problem of large reduction forces during fracture reduction surgeries and the need to collect multiple medical images. However, because its safety has not been certified, there are few academic achievements on this type of robot. To calculate the safety factor during its operation, a musculoskeletal model needs to be established to study the constraints of muscles on the robot. The existing academic achievements of musculoskeletal modelling are mainly for application such as rehabilitation treatment and collision in car accidents. METHODS: A musculoskeletal model applied to the fracture reduction robot is proposed in this paper. First, by comparing the characteristics of mainstream muscle models and combining the biological characteristics of the anesthetised muscles, the Hill model was selected as the muscle model for this study. Second, based on the motion composition of six spatial degrees of freedom, five basic fractural malposition situations are proposed. Then, a 170-cm tall male musculoskeletal model was built in Opensim. Based on this model, the muscle force curves of the above malposition situations are calculated. Finally, a similar musculoskeletal model was established in Adams, and the accuracy of its muscle force data was tested. The study is approved by the ethics committee of the Rehabilitation Hospital, National Research Center for Rehabilitation Technical Aids, Beijing, China. RESULTS: The muscle force curve of Opensim and Adams model under situations of five basic malposition are compared. Most of the correlation coefficients are in the range of 0.98-0.99. The overall correlation coefficient is greater than 0.95. CONCLUSIONS: The simulation results prove that this model can be used for the safety assessment of the fracture reduction robots. This model will be served as an environmental constraint to study the control of fracture reduction robot.

Microbes Associated With Black Soldier Fly (Diptera: Stratiomiidae) Degradation of Food Waste.

Black soldier fly (Hermetia illucens L.) larvae are capable of valorizing waste by converting it into insect biomass that can be used as animal feed, leaving undigested residue that can be used as soil enrichment. Evidence is conflicting over whether larvae fed substrate containing pathogenic microbes emerge uncontaminated. Studies also differ on which clades comprise the species' gut microbiome, and on whether and how diet affects these microbes. Using culturing and metabarcoding, the bacterial microbiota of black soldier fly larvae reared on two different kinds of food waste (postproduction soy pulp and postconsumer cafeteria waste) were analyzed, along with the microbes of their substrates. Little to no overlap was found between the wastes, the larvae, and the residues, but the larvae fed different foods had a significant percentage of their microbes in common. The data, in line with other works on this species, suggest the larvae have a conserved microbiota whose components vary geographically.