Structure design, kinematics analysis, and effect evaluation of a novel ankle rehabilitation robot

This paper presents a novel ankle rehabilitation (2-CRS+PU)&R hybrid mechanism, which can meet the size requirements of different adult lower limbs based on the three-movement model of the ankle. This model is related to three types of movement modes of the ankle movement, without axis offset, which can cover the ankle joint movements. The inverse and forward position/kinematics results analysis of the mechanism is established based on the closed-loop vector method and using the optimization of particle groups algorithm. Four groups of position solutions of the mechanism are obtained. The kinematics simulation is analyzed using ADAMS software. The variations of the velocity and acceleration of all limbs are stable, without any sudden changes, which can effectively ensure the safety and comfort of the ankle model end-user. The dexterity of the mechanism is analyzed based on the transport function, and the results indicate that the mechanism has an excellent transfer performance in yielding the structure parameters. Finally, the rehabilitation evaluation is conducted according to the three types of movement modes of the ankle joint. The results show that this ankle rehabilitation mechanism can provide a superior rehabilitation function

The future is distributed: a vision of sustainable economics

“The Future is distributed: a vision of sustainable economies” is a collection of case studies on distributed economies, a concept describing sustainable alternatives to the existing business models. The authors of this publication are international Masters students of the Environmental Sciences, Policy and Management Programme at the International Institute for Industrial Environmental Economics at Lund University in Sweden. The aim of their work is to demonstrate that local, small-scale, community-based economies are not just part of the theory, but have already been implemented in various sectors and geographical settings

The Prospects for Biogas Systems in Rural China: Incentives, Barriers and Potentials

Due to the multiple benefits of biogas systems, the Chinese Government has made great efforts to promote the development of biogas systems in rural China, especially household biogas plants and medium and large scale biogas plants to treat manure and waste water from intensive livestock and poultry farms. This thesis conducts a comprehensive literature review to understand the current situation of biogas systems in rural China in the light of feedstock, technologies and utilization of biogas and digested residue. A number of incentives and barriers affecting the production and utilization of biogas and digested residues are analyzed, in terms of policy, economy, technology and society. Based on the analysis of future social economic development in rural China, the examination of a variety of policies and the comprehensive literature review on the promotion of biogas plants, a number of measures are proposed. The policy advice for the development of household biogas plants in rural China is to slow down development, strengthen the education and training of farmers on the proper utilization of biogas plants, improve the rural biogas service network and ensure the quality of biogas plants as well as the associated facilities, and provide more funding for research and development of household biogas plants. As for medium and large scale biogas plants, in order to promote the further expansion, it is important to strengthen the enforcement of environmental protection law, develop multi-channels to raise the investments, set up the market for the products of medium and large scale biogas plants, and provide more funding for the capacity building of qualified technicians and improve the technology of biogas plants and auxiliary equipment for industrialization. A number of policy instruments are also suggested in this thesis to encourage the use of biogas and digested residue

Fractal cracking patterns in concretes exposed to sulfate attack

© 2019 by the authors. Sulfate attack tests were performed on concrete samples with three water-to-cement ratios, and micro-crack growth patterns on concrete surfaces were recorded. The expansive stress and crack nucleation caused by delayed ettringite formation (DEF) were studied using X-ray diffraction and scanning electron microscopy. By means of a digital image processing technology, fractal dimensions of surface cracking patterns were determined, which monotonously increase during corrosion. Moreover, it is shown that the change of fractal dimensions is directly proportional to accumulation of DEF, and therefore, a simple theoretical model could be proposed to describe the micro-crack evolution in concretes under sulfate attack

Entropy evolution during crack propagation in concrete under sulfate attack

In this paper, the corrosion experiment of concrete showed that the length and orientation of cracks, as well as their propagation direction are randomly distributed. By virtue of SEM and XRD techniques, the growth of delayed ettringite was detected, which leads to expansion stress and then induces the nucleation and propagation of cracks. To investigate the statistical characteristics of cracks, the concept of information entropy was adopted. Furthermore, based on the entropy evolution at different corrosion times and the chemical reaction rate of delayed ettringite, a model for entropy evolution was proposed. It is shown that the normalized entropy exponentially increases with the non-dimensional corrosion time

RB Particle Filter Time Synchronization Algorithm Based on the DPM Model

Time synchronization is essential for node localization, target tracking, data fusion, and various other Wireless Sensor Network (WSN) applications. To improve the estimation accuracy of continuous clock offset and skew of mobile nodes in WSNs, we propose a novel time synchronization algorithm, the Rao-Blackwellised (RB) particle filter time synchronization algorithm based on the Dirichlet process mixture (DPM) model. In a state-space equation with a linear substructure, state variables are divided into linear and non-linear variables by the RB particle filter algorithm. These two variables can be estimated using Kalman filter and particle filter, respectively, which improves the computational efficiency more so than if only the particle filter was used. In addition, the DPM model is used to describe the distribution of non-deterministic delays and to automatically adjust the number of Gaussian mixture model components based on the observational data. This improves the estimation accuracy of clock offset and skew, which allows achieving the time synchronization. The time synchronization performance of this algorithm is also validated by computer simulations and experimental measurements. The results show that the proposed algorithm has a higher time synchronization precision than traditional time synchronization algorithms

Lithium/Sulfide All-Solid-State Batteries using Sulfide Electrolytes

All-solid-state lithium batteries (ASSLBs) are considered as the next generation electrochemical energy storage devices because of their high safety and energy density, simple packaging, and wide operable temperature range. The critical component in ASSLBs is the solid-state electrolyte. Among all solid-state electrolytes, the sulfide electrolytes have the highest ionic conductivity and favorable interface compatibility with sulfur-based cathodes. The ionic conductivity of sulfide electrolytes is comparable with or even higher than that of the commercial organic liquid electrolytes. However, several critical challenges for sulfide electrolytes still remain to be solved, including their narrow electrochemical stability window, the unstable interface between the electrolyte and the electrodes, as well as lithium dendrite formation in the electrolytes. Herein, the emerging sulfide electrolytes and preparation methods are reviewed. In particular, the required properties of the sulfide electrolytes, such as the electrochemical stabilities of the electrolytes and the compatible electrode/electrolyte interfaces are highlighted. The opportunities for sulfide-based ASSLBs are also discussed

Multiscale monitoring of interface failure of brittle coating/ductile substrate systems: A non-destructive evaluation method combined digital image correlation with acoustic emission

In this paper, we proposed a non-destructive evaluation method combined digital image correlation with acoustic emission techniques. The method was used to in situ monitor interface failure and internal damage of brittle coating/ductile substrate systems with different size scales. The results show that there is a good relationship between digital image correlation and acoustic emission signals, which can be applied to judge cracking formation and coating delamination and to determine fracture toughness of a thermal barrier coating system subjected to bending

Treatment of PBDEs from Soil-Washing Effluent by Granular-Activated Carbon: Adsorption Behavior, Influencing Factors and Density Functional Theory Calculation

Soil-washing is a potential technology for the disposal of soil contaminated by e-waste; however, the produced soil-washing effluent will contain polybrominated diphenyl ethers (PBDEs) and a large number of surfactants, which are harmful to the environment, so the treatment of PBDEs and the recycling of surfactants are the key to the application of soil-washing technology. In this study, coconut shell granular-activated carbon (GAC) was applied to remove PBDEs from Triton X-100 (TX-100) surfactant which simulates soil-washing effluent. The adsorption results show that, GAC can simultaneously achieve effective removal of 4,4′-dibromodiphenyl ether (BDE-15) and efficient recovery of TX-100. Under optimal conditions, the maximum adsorption capacity of BDE-15 could reach 623.19 μmol/g, and the recovery rate of TX-100 was always higher than 83%. The adsorption process of 4,4′-dibromodiphenyl ether (BDE-15) by GAC could best be described using the pseudo-second-order kinetic model and Freundlich isothermal adsorption model. The coexistence ions had almost no effect on the removal of BDE-15 and the recovery rate of TX-100, and the solution pH had little effect on the recovery rate of TX-100; BDE-15 had the best removal effect under the condition of weak acid to weak base, indicating that GAC has good environmental adaptability. After adsorption, GAC could be regenerated with methanol and the adsorption effect of BDE-15 could still reach more than 81%. Density functional theory (DFT) calculation and characterization results showed that, Van der Waals interaction and π–π interaction are dominant between BDE-15 and GAC, and hydrogen bond interactions also exist. The existence of oxygen-containing functional groups is conducive to the adsorption of BDE-15, and the carboxyl group (-COOH) has the strongest promoting effect. The study proved the feasibility of GAC to effectively remove PBDEs and recover surfactants from the soil-washing effluent, and revealed the interaction mechanism between PBDEs and GAC, which can provide reference for the application of soil-washing technology