Design of Decision Tree Structure with Improved BPNN Nodes for High-Accuracy Locomotion Mode Recognition Using a Single IMU

Smart wearable robotic system, such as exoskeleton assist device and powered lower limb prostheses can rapidly and accurately realize man–machine interaction through locomotion mode recognition system. However, previous locomotion mode recognition studies usually adopted more sensors for higher accuracy and effective intelligent algorithms to recognize multiple locomotion modes simultaneously. To reduce the burden of sensors on users and recognize more locomotion modes, we design a novel decision tree structure (DTS) based on using an improved backpropagation neural network (IBPNN) as judgment nodes named IBPNN-DTS, after analyzing the experimental locomotion mode data using the original values with a 200-ms time window for a single inertial measurement unit to hierarchically identify nine common locomotion modes (level walking at three kinds of speeds, ramp ascent/descent, stair ascent/descent, Sit, and Stand). In addition, we reduce the number of parameters in the IBPNN for structure optimization and adopted the artificial bee colony (ABC) algorithm to perform global search for initial weight and threshold value to eliminate system uncertainty because randomly generated initial values tend to result in a failure to converge or falling into local optima. Experimental results demonstrate that recognition accuracy of the IBPNN-DTS with ABC optimization (ABC-IBPNN-DTS) was up to 96.71% (97.29% for the IBPNN-DTS). Compared to IBPNN-DTS without optimization, the number of parameters in ABC-IBPNN-DTS shrank by 66% with only a 0.58% reduction in accuracy while the classification model kept high robustness

Prediction Method of the Fuel Consumption of Wheel Loaders in the V-Type Loading Cycle

Wheel loaders in the V-type loading cycle are characterized by complicated loading conditions, nonlinear power-train system, and time-variable engine power distribution. Therefore, it is difficult to predict the fuel consumption of wheel loaders in the V-type loading cycle. The static matching methods cannot provide fuel consumption prediction for the loading cycle. In this paper, the prediction method and model of the fuel consumption for wheel loaders in the V-type loading cycle were proposed. Firstly, the hydraulic system data were tested when a wheel loader loaded three different materials in a typical V-type loading cycle. Secondly, the tested data were filtered by the 8th-order Butterworth filter and the dimensionless power deduction equations of hydraulic power system for loading three different materials were obtained by Gaussian and linear fitting based on the filtered data in the loading cycle. Finally, fuel consumption was obtained with the compiling dynamic calculation program as well as input parameters of tested vehicle speed, throttle parameter, and the dimensionless equation. The simulation results agreed well with experiment results. Dynamic calculation program is applicable to calculate loading economy and can provide academic guidance for wheel loader’s design and optimization

Laboratory-based Surveillance of Extensively Drug-Resistant Tuberculosis, China

To estimate the prevalence of extensively drug-resistant tuberculosis (XDR TB) in China, we retrospectively analyzed drug-resistance profiles of 989 clinical Mycobacterium tuberculosis isolates. We found 319 (32.3%) isolates resistant to >1 first-line drugs; 107 (10.8%) isolates were multidrug resistant, of which 20 (18.7%) were XDR. XDR TB is of major concern in China

Dietary protein sources differentially affect the growth of Akkermansia muciniphila and maintenance of the gut mucus barrier in mice

Scope: The gut microbiota plays an essential role in linking diet to host health. The specific role of different dietary proteins on the gut microbiota and health is less understood. Here we investigated the impact of proteins derived from chicken and soy on the gut microbiota and host gut barrier in C57BL/6 mice. Methods and results: Specific-pathogen-free and germ-free mice were assigned to either a chicken or a soy protein-based diet for 4 weeks. Compared with a chicken protein-based diet, intake of a soy protein-based diet reduced the abundance of A. muciniphila and the number of goblet cells, lowered the level of Muc2 mRNA, and decreased the thickness of the mucus layer in the colon of specific-pathogen-free mice. In germ-free mice colonization with A. muciniphila combined with intake of a chicken protein-based diet resulted in a higher expression of the Muc2 mRNA in colon, and surprisingly, an increased potential for oxidative phosphorylation in A. muciniphila compared with colonized mice fed a soy protein-based diet. Conclusion: These findings suggest possible mutually beneficial interactions between the growth and function of A. muciniphila and host mucus barrier in response to intake of a chicken protein-based diet contrasting the intake of a soy protein-based diet

Development of lower limb rehabilitation evaluation system based on virtual reality technology

Nowadays, with the development of the proportion of the elderly population in the world, several problems caused by the population aging gradually into people's horizons. One of the biggest problems plagued the vast majority of the elderly is hemiplegia, which leads to the vigorous development of the physical therapists. However, these traditional methods of physical therapy mainly rely on the skill of the physical therapists. In order to make up the defects of traditional methods, many research groups have developed different kinds of robots for lower limb rehabilitation training but most of them can only realize passive training which cannot adopt rehabilitation training based on the patients' individual condition effectively and they do not have a rehabilitation evaluation system to assess the real time training condition of the hemiplegic patients effectively. In order to solve the problems above, this paper proposed a lower limb rehabilitation evaluation system which is based on the virtual reality technology. This system has an easy observation of the human-computer interaction interface and the doctor is able to adjust the rehabilitation training direct at different patients in different rehabilitation stage based on this lower limb rehabilitation evaluation system. Compared with current techniques, this novel lower limb rehabilitation evaluation system is expected to have significant impacts in medical rehabilitation robot field

Research on the drilling winch control system for clean sampling of Antarctic Subglacial Lakes

Antarctica, with a large number of ice sheets, is among the last unexplored places on Earth. The subglacial lakes beneath these ice sheets have been isolated from the outside world for up to 35 million years, containing a diverse group of marine organisms and other materials. Its unique hydrological environment provides insights regarding microbial evolution and past climates on Earth, which have become central to interpreting the process of landscape evolution and assessments of possible future climate change. Clean sampling of subglacial lake water without introducing surface biological or other type of contamination has long been a goal of the international scientific community. The overlying ice thickness can reach thousands of meters and in conventional deep ice drilling, drilling fluids are employed while the boreholes exposed to the atmosphere. The only method for penetration is thermal drilling with the rate proportional to the vertical diameter of the drilling rig, which requires the drill body to be as thin as possible. The melted ice/water in the upper borehole will refreeze immediately once penetrating into the ice layers. Cables, thereby, need to be configured inside the drilling rig since separate cables from the external surface are not applicable in such cases. The drill rig comprises the motor-driven winch, outer surface heating system, control system as well as sampling system, totaling 600 kg in weight. Gear reducers are required during the cable lowering/lifting operations with a maximum outer diameter of the winch of 140 mm and a high-precision automatic synchronization between the reducers and cable lowering/lifting system is required. An automatic tension sensor along with a winch control system is designed to realize thee automatic synchronization between the gear reducers and the cable lowering/lifting system through servo control

Mathematical Model for Elliptic Torus of Automotive Torque Converter and Fundamental Analysis of Its Effect on Performance

Passenger car torque converters have been designed with an increasingly flatter profile in recent years for the purpose of achieving a weight saving and more compact size. However, a flatter design tends to result in the reduced hydrodynamic performance. To improve its performance, a new flat torus of elliptic type method concentrating on the solution to flat TC was put forward, and four torque converters of different flatness ratios were designed to judge the superiority of the flat torus design method. The internal flow characteristics were numerically investigated using CFD codes and resulted in good agreement with experimental data. The results indicate that the main cause of this performance degradation can be attributed to deterioration of the velocity fields of the pump, and a case of flatness ratio 0.8 illustrates the reason that the performance designed by the flat torus design method based on the elliptic shape is more excellent than that of the traditional one. Furthermore, this study proposed a structure of removal of inner ring to improve the performance of torque converter

Measurement and analysis of the internal flow field in the hydrodynamic torque converter with adjustable guide vanes

This article presents a particle-tracking velocimetry experiment for studying internal flows of hydrodynamic torque converter whose guide vanes are adjustable. The torque converter in which the flow region is an enclosed space with multiple impellers has a complicated geometry of impellers. Complex flows in adjustable stator are experimentally analyzed using particle-tracking velocimetry, and some advanced measurement technique has been successfully applied. Under each opening, using the single-frame and triple-exposure method, images of the flow fields in the adjustable stator were recorded at three typical working conditions as the speed ratios were equal to 0 (stall), 0.5 (design), and 1 (idle). According to particle trajectories on the images, the displacements and corresponding velocity vectors were obtained. The internal flow pattern of the hydrodynamic torque converter with adjustable guide vanes were acquired and analyzed in two cases: the changing conditions under the same opening and the changing openings under the same condition