Search

The control strategy of rehabilitation robots should not only adapt to patients with different levels of motor function but also encourage patients to participate voluntarily in rehabilitation training. However, existing control strategies usually consider only one of these aspects. This study proposes a voluntary and adaptive control strategy that solves both questions. Firstly, the controller switched to the corresponding working modes (including challenge, free, assistant, and robot-dominant modes) based on the trajectory tracking error of human-robot cooperative movement. To encourage patient participation, a musculoskeletal model was used to estimate the patient’s active torque. The robot’s output torque was designed as the product of the active torque and a coefficient, with the coefficient adaptively changing according to the working mode. Experiments were conducted on two healthy subjects and four hemiplegic patients using an ankle rehabilitation robot. The results showed that this controller not only provided adaptive the robot’s output torque based on the movement performance of patients but also encouraged patients to complete movement tasks themselves. Therefore, the control strategy has high application value in the field of rehabilitation.

Abstract Background Compared to nonsocial information, the human brain is more highly sensitive to social information. As a kind of typical social semantic information, the words describing person traits differ from the nonsocial semantic information describing inanimate objects in many ways. It remains to be seen whether the processing of trait words has a valence asymmetric and whether it differs from the processing of nonsocial semantic information in terms of behavioral responses and neural temporal processes. Method Taking person and object names as priming stimuli and adjective words only used for describing humans or objects as target stimuli, the present study aimed to investigate the processing characteristics of social and nonsocial semantic information by recording both behavioral and ERP data. Results Behavioral results showed that the response times for negative words were significantly slower than those for positive words whether for social or nonsocial semantic information. The accuracy rates of negative words were significantly lower than those of positive words when the targets were social words which is contrary to the nonsocial words. The ERP results indicated that there was a negative bias effect on the processing of both types of information during the whole time course of brain neural activity; that is, the P2, N400, and LPP amplitudes elicited by negative words were larger than those elicited by positive words; However, the negative bias effect of social semantic information started at the early perceptual stage which was significantly earlier than the onset of negative bias of nonsocial semantic information, and was significantly affected by the prime type. In addition, there was a significant semantic conflict N400 effect only for nonsocial semantic information. Conclusions Overall, the present study revealed the existence of an early negative bias of social information and provided evidence for the specificity of social information.

To effectively solve the problems of environmental pollution and resource waste caused by steel slag and open up a new field of application of steel slag, the porous magnetic steel slag abrasive was prepared by combining the gas quenching process with steel slag as the main raw material. Besides, and the micro-morphology, the pore structure, the magnetic properties, the mechanical properties and the abrasive properties of steel slag abrasive were characterized by field emission scanning electron microscope, high-performance automatic mercury porosimeter, magnetometer, etc. The results show that the steel slag abrasive is monodisperse spherical, and there are disordered pores arranged in round or elliptical shape on its surface and cross section. The porosity of abrasive sample is 37% to 45%, and the pore volume is 0.18 to 0.23 mL/g. Under the action of external magnetic field, with the increase of the particle size of the abrasive sample, its hysteresis loop shifts clockwise and presents a narrow “S” type closed curve. The abrasive sample shows typical ferrous magnetism, which can effectively improve the surface quality of aluminum alloy workpiece, and the surface roughness Ra of the workpiece is reduced from 3.2 µm to 0.7 µm.

Most of the blockchain-based identity authentication systems are based on public blockchain, which are still essentially traditional centralized identity management and verification methods, making it difficult to meet the needs of trusted access and fine-grained access control in microgrids.Therefore, based on the FISCO BCOS consortium blockchain technology, a distributed identity authentication system supporting multi-center was designed.A DID-based identity management protocol to achieve autonomous control of user identity in a practical scenarios was designed.Distributed trusted access technology for end nodes in microgrids was studied, and privacy-protecting credentials based on zero-knowledge proof were designed.This scheme meets the requirements of trustworthy and verifiable user identity in different privacy security scenarios, and achieves autonomous control of entity identity, fine-grained access control and trusted data exchange.The usability and effectiveness of the proposed algorithm are demonstrated through system experiments and performance analysis.

Kitchen waste is an important component of domestic waste, and it is both harmful and rich in resources. Approximately 1.3 billion tons of kitchen waste are produced every year worldwide. Kitchen waste is high in moisture, is readily decayed, and has an unpleasant smell. Environmental pollution can be caused if this waste is treated improperly. Conventional treatments of kitchen waste (e.g., landfilling, incineration and pulverization discharge) cause environmental, economic, and social problems. Therefore, the development of a harmless and resource-based treatment technology is urgently needed. Profits can be generated from kitchen waste by converting it into biofuels. This review intends to highlight the latest technological progress in the preparation of gaseous fuels, such as biogas, biohythane and biohydrogen, and liquid fuels, such as biodiesel, bioethanol, biobutanol and bio-oil, from kitchen waste. Additionally, the pretreatment methods, preparation processes, influencing factors and improvement strategies of biofuel production from kitchen waste are summarized. Problems that are encountered in the preparation of biofuels from kitchen waste are discussed to provide a reference for its use in energy utilization. Optimizing the preparation process of biofuels, increasing the efficiency and service life of catalysts for reaction, reasonably treating and utilizing the by-products and reaction residues to eliminate secondary pollution, improving the yield of biofuels, and reducing the cost of biofuels, are the future directions in the biofuel conversion of kitchen waste.

In the iron-ore-sintering process, the use of biomass charcoal instead of coke breeze can reduce the emission of flue gas pollutants and alleviate the energy crisis of fossil fuels. However, the direct application of biomass charcoal to iron ore sintering is bound to affect the sinter properties. The effects of biomass charcoal addition on the sintering ore properties and flue gas pollutants emission were studied through sintering cup and related performance test experiments. Meanwhile, the influence mechanism of biomass charcoal instead of coke breeze on iron ore sintering was expounded. The experimental results show that with an increase in biomass charcoal, the vertical sintering rate increased, the internal pore structure developed rapidly, and the pollutant emission decreased gradually. When the biomass charcoal content was less than 40%, the sinter strength and yield were stable and slightly improved with the increase in biomass charcoal. When the biomass charcoal content was higher than 40%, the metallurgical properties of sinter degraded sharply, making it difficult to meet the production requirements. The comprehensive effect of biomass charcoal on the sinter suggests that the suitable biomass charcoal addition was 40%; under this condition, the reduction in SO2 and NOx was 28.2% and 25.7%, respectively.

The process of granulation in blast furnace slag (BFS) by gas quenching can effectively recover the waste heat of BFS and improve the value-added nature of the BFS byproduct. With decreasing temperature, BFS crystallizes into melilite, anorthite, spinel, etc. Mineral crystallization, however, is not conducive to the production of amorphous BFS beads. This study uses thermodynamic simulation and remelting experiments to study the influences of basicity, acidity, and the MgO and Al2O3 content of the BFS on the crystallization. By controlling the composition of the BFS, mineral crystallization in the process of granulation in BFS, by gas quenching, could be prevented. The results show that increasing the basicity of the BFS causes the mineral crystallization temperature to increase rapidly. The mineral phase then crystallizes at a higher temperature, which is not conducive to the formation of an amorphous phase. Increasing the acidity of the BFS can greatly decrease the crystallization temperature, e.g., when the acidity increases to 1.3, amorphous BFS beads can be obtained at the gas quenching temperature (1623 K). Although increasing the MgO and Al2O3 contents in the BFS had little effect on the crystallization temperature and yield, the preparation of amorphous BFS beads by gas quenching could be realized by adjusting the acidity of the BFS.

The use of the gas-quenching process for preparing porous bead slag abrasive was investigated in this paper. An X-ray diffractometer, field emission scanning electron microscope, mercury intrusion porosimetry, and stereo microscope were used to analyze the microbead forming mechanism, pore structure, acid–alkali resistance, and polishing properties of porous steel slag microbead abrasives. Results show that the porous steel slag abrasives present a mono-disperse spherical shape with a hard shell and the porosity is 42.36%. The thermodynamic fractal model indicates that the fractal dimension of the abrasive is 2.226, which shows its simple pore structure. The sample has better chemical stability in the polishing fluid than in water, acid, and alkali solution. Therefore, aluminum and copper alloys are used as substrates for polishing tests. The results indicate that the abrasives could effectively improve the quality of the workpiece surface and the polishing efficiency for aluminum alloy was higher than that for copper alloy.

Most of the air pollutants in the steel industry come from the sintering process, and the air pollutants produced by the sintering process mainly come from the sinter fuel (coke breeze). The S and N content of biomass fuel is low; therefore, biomass fuel is used instead of coke breeze for sintering to reduce the emission of the sinter flue gas pollutants. However, the use of biomass fuel reduces the sintering layer temperature, which results in the deterioration of the sinter properties. In order to ensure the quality of sintering base on biomass fuel, the thermodynamic calculation and related experiments were carried out, the effects of different basicity, MgO and Al2O3 content on the formation of low melting point minerals in sintered mixture were studied, and the suitable composition of sintered mixture was determined in this paper, so as to reduce the liquid phase formation temperature of sinter and increase in biomass fuel addition, which provided theoretical support for the application of biomass fuel in sintering. Experimental results indicate that the suitable conditions for the low-temperature sintering were a basicity of 2.0, and MgO and Al2O3 contents of 1.0% and 1.8%, respectively. Under this condition, more biomass fuel can be used to replace coke breeze, and the emission of flue gas pollutants can be greatly reduced.

Titanium alloy has been widely applied in industrial engineering products due to its advantages of great corrosion resistance and high specific strength. This paper investigated the processing parameters for finish turning of titanium alloy TC11. Firstly, a three-factor central composite design of experiment, considering the cutting speed, feed rate and depth of cut, are conducted in titanium alloy TC11 and the corresponding surface roughness are obtained. Then a mathematic model is constructed by the response surface methodology to fit the relationship between the process parameters and the surface roughness. The prediction accuracy was verified by the one-way ANOVA. Finally, the contour line of the surface roughness under different combination of process parameters are obtained and used for the optimum surface roughness prediction. Verification experimental results demonstrated that material removal rate (MRR) at the obtained optimum can be significantly improved without sacrificing the surface roughness. Keywords: Titanium alloy, Surface roughness, Response surface methodology, Design of experiment, Iso-surface

Slag beads with different crystal content could be obtained through the gas quenching blast furnace slag (BFS) process. In order to increase the additional value of the slag beads as much as possible, it was necessary to restrain the crystallization of the slag beads as much as possible. In this paper, the mineral types and crystallization temperatures of BFS with different basicities and cooling rates were studied by using Factsage thermodynamic software, XRD, and differential scanning calorimeter (DSC) experiments, which obtained the gas quenching temperature and the cooling rate needed to restrain crystallization behavior in the gas quenching process; The crystallization mechanism was studied by calculating crystallization activation energy (Ec) using the DSC experiment, at the same time, the thermodynamic results were verified. The proper basicity and cooling rate of BFS were found to be conducive to the preparation of amorphous slag beads. The results showed that the initial crystallization temperature decreased with decreasing the basicity and increasing the cooling rate, which could increase the amorphous content of slag beads in the gas quenching process. The crystallization activation energy (Ec) increased with decreasing basicity, which increased the crystallization barrier.

Ecological restoration refers to the containment of soil erosion, restoration of water conservation, climate regulation, maintenance of ecological functions of biodiversity, and improvement of ecological environment and landscape pattern based on self-repairing capacity of the nature and combined with appropriate artificial measures. Since the natural restoration process of karst desertification mountain is very long, it needs to be supplemented by artificial vegetation restoration. This paper introduced the ecological restoration technologies implemented in karst rocky desertification mountains in Xixiu District, Anshun City of Guizhou Province, and also introduced the afforestation tending management measures. It assessed the ecological benefits of the ecological restoration project from five aspects: mountain community characteristics, vegetation coverage, species diversity, afforestation survival rate and landscape effect. [ABSTRACT FROM AUTHOR]

SiC material is a kind of material with excellent properties, in order to inhibit it's oxidation behaviour and prolong the service life of the material during the process of using, the oxidation behaviour of three kinds of SiC materials containing different amounts of Cp in the three temperature ranges from 400oC to 1100oC is studied in this paper. It emphatically analyzes the relations among Cp/SiC's quality change fraction in air and oxidation temperature, oxidation time, Cp/SiC's apparent porosity and oxidation temperature, Cp/SiC's bending strength and oxidation temperature, oxidation time. It is concluded that the Cp content of SiC is the key factor to influence the strength and oxidation behaviour of composite materials and the kind of SiC composite ceramics which add Cp can improve oxidation resistance of the materials. [ABSTRACT FROM AUTHOR]

In order to study the effect of cutting speed, feed and tool wear of superalloy Inconel625 on machined surface quality, coated carbide tools CNMG120408 were selected to carry out turning test under different cutting conditions. The change laws of roughness of machined surface, surface work hardening and white layer were analyzed under the condition of different cutting speed, feed and tool wear. The results showed that the machined surface roughness has been reduced from 1.140 µm to 0.640 µm with the increase of cutting speed, the surface roughness value increased with the increase of feed and flank wear and the depth of work hardening layer decreased with the increase of cutting speed, while work hardening rate was improved. The depth of work hardening layer was increased with the improvement of feed and flank wear. Tool wear, cutting temperature and the thickness of white layer gradually was increased with the increase of cutting speed. Meanwhile, the critical temperature of the material phase transition has been reduced because of the severe plastic deformation in the cutting process, which leads to the formation of white layer at low cutting temperature. [ABSTRACT FROM AUTHOR]