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As wheeled mobile robots find increasing use in outdoor applications, it becomes more important to reduce energy consumption to perform more missions efficiently with limit energy supply. The purpose of this paper is to survey the current state-of-the-art on energy-efficient motion planning (EEMP) for wheeled mobile robots.

The use of wheeled mobile robots has been increased to replace humans in performing risky missions in outdoor applications, and the requirement of motion planning with efficient energy consumption is necessary. This study analyses a lot of motion planning technologies in terms of energy efficiency for wheeled mobile robots from 2000 to present. The dynamic constraints play a key role in EEMP problem, which derive the power model related to energy consumption. The surveyed approaches differ in the used steering mechanisms for wheeled mobile robots, in assumptions on the structure of the environment and in computational requirements. The comparison among different EEMP methods is proposed in optimal, computation time and completeness.

According to lots of literature in EEMP problem, the research results can be roughly divided into online real-time optimization and offline optimization. The energy consumption is considered during online real-time optimization, which is computationally expensive and time-consuming. The energy consumption model is used to evaluate the candidate motions offline and to obtain the optimal energy consumption motion. Sometimes, this optimization method may cause local minimal problem and even fail to track. Therefore, integrating the energy consumption model into the online motion planning will be the research trend of EEMP problem, and more comprehensive approach to EEMP problem is presented.

EEMP is closely related to robot’s dynamic constraints. This paper mainly surveyed in EEMP problem for differential steered, Ackermann-steered, skid-steered and omni-directional steered robots. Other steering mechanisms of wheeled mobile robots are not discussed in this study.

The survey of performance of various EEMP serves as a reference for robots with different steering mechanisms using in special scenarios.

This paper analyses a lot of motion planning technologies in terms of energy efficiency for wheeled mobile robots from 2000 to present.

With the dramatically increasing number of substations, robots are expected to inspect equipment in the power industry. However, a traditional robotic system cannot work stably because of the strong electromagnetic field in substation. The purpose of this paper is to present a robust and stable robotic system for inspecting the substation equipment without the involvement of workers.

The paper presents in detail a robotic system that consists of a monitor center and a robot. With the monitor center, the workers could send inspection tasks and monitor status of the robot timely. Once a fault is detected, the alarm message will flash immediately to remind the workers. The patrol mode of the robot comprises teleoperation, regular inspection, special inspection and a key return mode. The robot only relies on a low-cost magnetic sensor for lateral positioning and radio frequency identification technology for longitudinal positioning when working under patrol mode. At each stop point, the substation equipment can be recognized quickly through accurate matching with the template image stored in the database.

It is shown that the robot could work efficiently and reliably in power substations. The positioning error is proved to be within 5 mm, compared to that of 20 cm by implementing integrated global positioning system-dead reckoning navigation. Because of the high positioning accuracy, it is much easier to recognize the substation equipment. It is observed that nearly 99 per cent of equipments can be recognized.

The proposed robotic system is tested in a simple substation environment. While the proposed system shows satisfactory positioning results, further studies considering changeable weather condition will focus on improving the equipment recognition rate in such environment, such as rainy, snowy and strong sunlight.

The key contribution of this paper is that it provides a robotic system to inspect substation equipment instead of workers, to improve working efficiency and to reduce manpower cost.

This paper presents a robotic system to inspect substation equipment instead of workers. Four patrol modes are designed to meet the inspection demand. Comparing with the previous robotic systems, this system contributes to higher position accuracy and higher equipment recognition rate.

The purpose of this paper is to study conducted electromagnetic interference (EMI) of the high-low voltage DC/DC converter based on GaN high-electron-mobility transistors (HEMTs) in electric vehicle, and design EMI filters to suppress the conducted EMI.

The conducted EMI propagation model is established through simulation and analysis studying the influences of parasitic parameters, operation mode, output power and near-field capacitive coupling effects on conducted EMI of the DC/DC converter and comparing the suppression effects of EMI filters with different topologies to select the best EMI filter.

It is shown that parasitic parameters, operation mode, output power and near-field capacitive coupling effects can affect the conducted EMI of the DC/DC converter, and EMI filters of the CLC topology can effectively suppress the conducted EMI below the limit of CISPR 25.

Analysis of conducted EMI and design of EMI filters greatly facilitate further explorations and studies on EMI problems of the high-low voltage DC/DC converter based on GaN HEMTs.

This study aims to investigate the two-dimensional magnetohydrodynamic flow and heat transfer of a fractional Maxwell nanofluid between inclined cylinders with variable thickness. Considering the cylindrical coordinate system, the constitutive relation of the fractional viscoelastic fluid and the fractional dual-phase-lag (DPL) heat conduction model, the boundary layer governing equations are first formulated and derived.

The newly developed finite difference scheme combined with the L1 algorithm is used to numerically solve nonlinear fractional differential equations. Furthermore, the effectiveness of the algorithm is verified by a numerical example.

Based on numerical analysis, the effects of parameters on velocity and temperature are revealed. Specifically, the velocity decreases with the increase of the fractional derivative parameter α owing to memory characteristics. The temperature increase with the increase of fractional derivative parameter ß due to a decrease in thermal resistance. From a physical perspective, the phase lag of the heat flux vector and temperature gradients τ_q and τ_T exhibit opposite trends to the temperature. The ratio τ_T/τ_q plays an important role in controlling different heat conduction behaviors. Increasing the inclination angle θ, the types and volume fractions of nanoparticles Φ can increase velocity and temperature, respectively.

Fractional Maxwell nanofluid flows from a fixed-thickness pipe to an inclined variable-thickness pipe, and the fractional DPL heat conduction model based on materials is considered, which provides a basis for the safe and efficient transportation of high-viscosity and condensable fluids in industrial production.

Sentiment identification of Chinese text faces many challenges, such as requiring complex preprocessing steps, preparing various word dictionaries carefully and dealing with a lot of informal expressions, which lead to high computational complexity.

A method based on Chinese characters instead of words is proposed. This method represents the text into a fixed length vector and introduces the chi-square statistic to measure the categorical sentiment score of a Chinese character. Based on these, the sentiment identification could be accomplished through four main steps.

Experiments on corpus with various themes indicate that the performance of proposed method is a little bit worse than existing Chinese words-based methods on most texts, but with improved performance on short and informal texts. Especially, the computation complexity of the proposed method is far better than words-based methods.

The proposed method exploits the property of Chinese characters being a linguistic unit with semantic information. Contrasting to word-based methods, the computational efficiency of this method is significantly improved at slight loss of accuracy. It is more sententious and cuts off the problems resulted from preparing predefined dictionaries and various data preprocessing.