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The track impedance is one of the most important parameters in designing the track circuit which is widely used in the railway signal control system to detect the presence of a train. This paper aims to calculate the ballastless track impedance by taking account of the influence of reinforcement bars.

This paper proposes a two-step decomposition approach to calculate the ballastless track impedance. The basic idea is evaluating the track impedance without the reinforcement bars by using two-dimensional (2D) finite element method (FEM), and the incremental impedance, because of the reinforcement bar, is calculated by the partial element equivalent circuit (PEEC) method.

The numerical examples show that the proposed approach can guarantee the accuracy and largely reduce the computing time, at least 20 times, compared with the direct three-dimensional (3D) FEM method.

The study provides a fast approach to calculate the ballastless track impedance. However, compared with the 3D FEM method, the results are less accurate because of the approximation and assumption adopted in the method. A future study should pay more attention to improve accuracy of the model.

A fast approach is proposed to calculate the ballastless track impedance taking account of the influence of the reinforcement bars. The computing time can be largely reduced by using the method. With the proposed approach, the influence of insulation of the reinforcement bars on track impedance can be analyzed.

Snake-inspired robots are of great significance in many fields because of their great adaptability to the environment. This paper aims to systematically illustrate the research progress of snake-inspired robots according to their application environments. It classifies snake-inspired robots according to the numbers of degrees of freedom in each joint and briefly describes the modeling and control of snake-inspired robots. Finally, the application fields and future development trends of snake-inspired robots are analyzed and discussed.

This paper summarizes the research progress of snake-inspired robots and clarifies the requirements of snake-inspired robots for self-adaptive environments and multi-functional tasks. By equipping various sensors and tool modules, snake-inspired robots are developed from fixed-point operation in a single environment to autonomous operation in an amphibious environment. Finally, it is pointed out that snake-inspired robots will be developed in terms of rigid and flexible deformable structure, long endurance and multi-function and intelligent autonomous control.

Inspired by the modular and reconfigurable concepts of biological snakes, snake-inspired robots are well adapted to unknown and changing environments. Therefore, snake-inspired robots will be widely used in industrial, military, medical, post-disaster search and rescue applications. Snake-inspired robots have become a hot research topic in the field of bionic robots.

This paper summarizes the research status of snake-inspired robots, which facilitates the reader to be a comprehensive and systematic understanding of the research progress of snake-inspired robots. This helps the reader to gain inspiration from biological perspectives.

This paper aims to demonstrate the principle and practical applications of hyperspectral object detection, carry out the problem we now face and the possible solution. Also some challenges in this field are discussed.

First, the paper summarized the current research status of the hyperspectral techniques. Then, the paper demonstrated the development of underwater hyperspectral techniques from three major aspects, which are UHI preprocess, unmixing and applications. Finally, the paper presents a conclusion of applications of hyperspectral imaging and future research directions.

Various methods and scenarios for underwater object detection with hyperspectral imaging are compared, which include preprocessing, unmixing and classification. A summary is made to demonstrate the application scope and results of different methods, which may play an important role in the application of underwater hyperspectral object detection in the future.

This paper introduced several methods of hyperspectral image process, give out the conclusion of the advantages and disadvantages of each method, then demonstrated the challenges we face and the possible way to deal with them.

The purpose of this paper is to assess the immediate and lagged effects of founder's turnover on firm performance, and test the moderating effects of enterprise scale and founders' tenure on enterprise performance.

The paper selects 307 listed companies founded by founder from the Listed Company's Financial Database provided by the China Center for Economic Research. Based on 1,535 observations, this paper tests the relationship between founder turnover and performance by using the random effect model and the fixed effect model.

It is found that founders' turnover will have a significant immediate and negative effect on firm performance. There exists a lagged effect of founders' turnover, but this lagged effect is not as strong as immediate effect. It is also found that the effect of founders' turnover has been moderated by firm size and founders' characteristics.

Founders should choose an appropriate time of leaving when the firm's performance has reached a level high enough for the successor to have a better chance of improving its future operations.

Although some scholars have recognized the special role of founders and that enterprises' performances are mainly determined by the founders, few have studied founders' turnover on firm performance directly and empirically. This paper expands understanding of the founders' departure behavior on firm performance.

The main purpose of this study is to see the effects of Information Communication Technology (ICT) on a firm's innovation performance in sub-Saharan Africa (SSA). The objective of this study is twofold: First, it aims to analyze the impact of ICT applications on firms' innovative behavior and whether firms using ICT applications more intensively are also more innovative. Second, and more essentially, it assesses empirically the impact of ICT applications on firms' innovative performance in sub-Saharan African countries by using instrumental variable probit model. Therefore, we used data from the 2013 enterprise survey (Business Environment and Enterprise Performance Survey (BEEPS)). According to our results, the most important ICT tools are emails and using the internet for online sales. Firms who have IT Teams are not creating any difference; however, if a firm purchase or develop in-house any software then they are more likely to produce innovation than the other firms.

During the service condition of residential constructions with concrete structure, the influence of inside and exterior factors will result in different degrees of harm to concrete engineering. Therefore, it is very necessary to continue engineering work toward the concrete structure. Therefore, the purpose of this study is to evaluate the influence of the factors on the comprehensive performance of the concrete structure engineering.

Applying a mathematics method to establish the comprehensive evaluation model of the concrete structure engineering performance, qualitative and quantitative methods were adopted for reinforced concrete structural performance analysis.

The key to a safe construction project is to require all bidders to submit a written safety plan with their bids. The instruction to bidders must include guidelines for an acceptable safety plan and state clearly that the substance of the safety plan will be reviewed, and its adequacy will be a determining factor in who shall be selected as the contractor.

Based on the characteristics of concrete structure, applying the analytic hierarchy process to evaluate the concrete structure engineering comprehensive performance, an evaluation index system was built. The research combines quantitative method with qualitative method evaluation was made.

To address the lack of data in this field and determine the relationship between the coefficient of friction and the interference between locomotive wheels and axles, this study evaluates the theoretical relationship between the coefficient of friction and the interference under elastic deformation.

When using numerical analyses to study the mechanical state of the contacting components of the wheels and axle, the interference between the axle parts and the coefficient of friction between the axle parts are two important influencing factors. Currently, as the range of the coefficient of friction between the wheel and axle in interference remains unknown, it is generally considered that the coefficient of friction is only related to the materials of the friction pair; the relationship between the interference and the coefficient of friction is often neglected.

A total of 520 press-fitting experiments were conducted for 130 sets of wheels and axles of the HXD2 locomotive with 4 types of interferences, in order to obtain the relationship between the coefficient of friction between the locomotive wheel and axle and the amount of interference. These results are expected to serve as a reference for selecting the coefficient of friction when designing axle structures with the rolling stock, research on the press-fitting process and evaluations of the fatigue life.

The study provides a basis for the selection of friction coefficient and interference amount in the design of locomotive wheels and axles.

This paper aims to investigate the friction and wear properties of Cr-Ni-Mo-V steel against 440C stainless steel under both water and water–silica mixture lubricant.

The Cr-Ni-Mo-V steel specimens were taken from a forged steel brake disc with the process of quenching at 900°C and tempering at 600°C. The tribological testing was performed using a contact configuration of ball-on-flat with a liquid cell according to the ASTM standard. Detailed examinations on the worn surface were analyzed using a scanning electron microscope.

The results indicate that the friction coefficient and friction damage of the steel sliding under water–silica mixture are higher than those under water. The friction coefficient decreases with increasing load and increases with the sliding speed for the two lubricants. The mass wear rate presents a rising trend with both sliding load and speed. The wear mechanisms of the Cr-Ni-Mo-V steel sliding under the two lubricants are oxidation wear, abrasive wear and fatigue wear.

Because of the chosen tribological testing approach, the research results could not describe the tribological performance of the brake disc accurately during actual braking process of the high-speed train. Therefore, researchers are encouraged to test the proposed propositions further.

This study shows that the tribology behavior of the Cr-Ni-Mo-V steel with water or water–silica mixture lubrications helps the industrial firms and academicians to work on the wear of the brake disc in rainwater or wet environment.