Search

To study the distribution and regularity of the longitudinal force of continuously welded rail on a railway bridge, a railway suspension bridge with a span of (84 + 84 + 1092 + 84 + 84) m is taken ...

Human robot interaction is playing significant roles in many industries, in which humans are allowed to corporate with robots or control robots to complete some tasks. Achieving realtime control of robots by demonstrating human arm motion is one of the effective methods to improve the quality of human robot interaction. In this paper, a new method to accomplish human skeleton key points extraction is proposed and a system for controlling a virtual UR5 robot (which is modeling in Unity 3D) is developed to imitate human motions. A sequential architecture composed of convolutional networks is used to identify the 2D coordinates; the depth information from Kinect v2 sensor is used to obtain the actual 3D coordinates and the result of the proposed method is used for joint angles calculation. The appropriate mapping relationships between human arm and UR5 robots are built by transforming the arm angel to UR5's degrees of freedom. The performance of this method is measured by the degree of real-time simulation of human hand trajectory. Further, the comparison between the method in this paper and other method is implemented. The experimental results indicate that the developed system and proposed method are reliable and efficient to accomplish human motion imitation.

Manufacturing activities in cloud-based environments strongly rely on the online integration and description of the capability of machining resources. In the authors’ previous work, STEP-NC schema was applied to construct an ontology model to support the integration and reasoning of machine tool information and capability. For the maintenance and update of the model, in this paper, a self-learning method is proposed to explore correlations from STEP-NC process planning documents to obtain machining knowledge to improve the comprehensiveness of the model. In this method, a Map/Reduce-based Apriori algorithm is developed incombination with the built ontological model. First, a dataset is extracted from the document according to the importance analysis results of the model. Then, a mining procedure that combinesApriori algorithm and Map/Reduce framework is developed. Finally, two representation modes are adopted to embed the mined results into the model. According to the outcomes of a preliminary experiment with standard STEP-NC documents, this method effectively enables the ontology learning mechanism from the aspects of time consumption and mined associations, which improves the suitability of the enriched ontology model to handle information integration and industrial applications.

Atmospheric temperature and directed solar radiation have a significant effect on the temperature field of high-speed railway (HSR) concrete bridge and ballastless track structure. However, temperature actions are random process of which distribution laws are difficult to explore, and existing statistical methods for structure temperature analysis are still not precise. So far, there are few researches for annual temperature spectra and design codes for bridge–track system. Based on the one-year observation data, this paper investigated the temperature actions for Chinese HSR bridge–track structure. By utilizing reliability high moment theory, a statistical method which could built virtual distribution was put forward. Based on the renewed study, the effects of waterproof for deck were taken into consideration, a temperature action model was proposed which is suitable for both bridge and track structure. In addition, for track structure, the previous temperature load models were modified. Apart from that, by proposing the concepts of temperature uniform and fluctuant spectra, the research evaluated service performance of structure. Finally, the distribution regularities of uniform temperature spectra were fitted by Fourier series, and the relationship between structural and atmospheric uniform temperature was established (formula (25) ). As a result, according to 50 years recorded atmospheric temperature data, the prediction model of the structure extreme temperature was suggested, and by taking the recurrence interval of 100, 150 and 300 years, the extreme temperatures of the system are 52.23, 54.34 and 57.77 °C.

The railway engineering major shows extremely strong applicability, with the internationalization of railway engineering teaching and communication, how to solve the problem of cultivating the international students of the railway engineering major experimental teaching is a core problem that the railway engineering majors in universities need to solve at this stage. Through reform, a new type of experimental teaching system for railway engineering specialty was constructed, that is, the experimental course system and content system determined by the international students training program were taken as the core, the construction of teachers, experimental facilities, practice bases and other conditions as the basis, and the system construction and operation organization to build an organic whole composed of four elements for guarantee. It is closely integrated with the theoretical teaching system and relatively independent. It guarantees the realization of the goal of international students training. And it can integrate and optimize the experimental teaching links, content, methods and evaluation system, and build a “gradual experiment-professional experiment-comprehensive experiment” progressive gradient experiment teaching system. Form a benign pattern of collaborative training of laboratories, practice bases and scientific research bases, mutual promotion of teaching and scientific research, and effectively promote the improvement of students’ experimental innovation ability.

With the continuous development of China's social economy, it has correspondingly promoted the development of the railway engineering experimental career, and has made tremendous progress in the cultivation of railway engineering experimental talents. At the same time, there are still many problems in the development of rail transit in the construction of "double first-class". Only by solving the existing problems can we further promote the smooth development of the training of railway engineering experimental talents. Therefore, the article mainly analyzes the problems and countermeasures of railway engineering experimental training, combined with the status and role of laboratories in the training of talents under the background of "double first-class", according to the society's demand for first-class engineering talents, we reformed and explored laboratory resource integration and optimization.

This paper presents a spiral bevel gear strain measurement using optical fiber gratings. High-speed and heavy-duty spiral bevel gear (SBG) is the key component of the power transmission of intersection axes. Its dynamic mechanical properties greatly influence the working performance of the machine. By building a strain detecting system based on FBG demodulation, we carried out real-time measurements of the distributed strain in the SBG with different torques and different rotation speed. The experimental results show a complete strain waveform from gear-in to gear-out, verifying the feasibility of measuring the strain of SBG using optical fiber gratings.

In the power system, the substation as the most important node to connect the transmission system with distribution system is an important factor to determine whether the power system is under the normal operation. Real-time recognition of the operation status of the equipment in the substation by using the recognition technology based on the infrared image target extraction can timely observe the equipment fault points, and help the repair and maintenance personnel to eliminate the fault points timely. This paper will focus on the noise reduction, segmentation and recognition of the substation infrared image by using the recognition technology based on the infrared image target extraction, so as to extract necessary features and the technology and algorithm about data for real-time monitoring of the equipment in the substation, and improve the evaluation of the operational safety of the equipment in the substation.

Particulate detection, which is based on lock-in amplifier technology, requires a phase-shift signal generator with wide frequency range and high phase shift precision. Since the current phase-shift signal generator has a deficiency of low precision in high frequency range, the author designed a phase-shift generator which adopts direct digital frequency synthesis technology, and expresses hardware design principles of the system. This paper focuses on the design of hardware and software concerning high precision phase shift and amplitude closed-loop control. The experimental results indicate that the output signals have a high accuracy in phase difference, frequency and amplitude under a wide frequency range and this system achieves the requirements of particulate detection.

This paper introduces the principle of valve regulated lead acid batteries (VRLA) on-line monitor-internal resistance measurement of monocell's transient twice constant current discharge. Hardware design and software program based on this principle were analyzed in detail, and experimental results were put forward. The system, with the function of remote control and measurement, is convenient to realize the automatization of invalid battery detection.

This paper is concerned the limitation of the knowledge and its discovery and propaganda processes. All the knowledge is the reflection of the world and knowledge itself. We can divide the knowledge into static and dynamic forms according by its object. Static knowledge can't be perfect as the Set theory has proved. Dynamic knowledge can't be Precise. All the knowledge can't handle the world as a whole. The propaganda process of the knowledge has limitation too, because the density of the knowledge can't be infinite. So we have to admit that the knowledge have left the space for the belief and random. Furthermore the world is undetermined in the boundary of human being's intelligence.

For the energy shortage in China's coastal areas, which has exerted severe impact on economy development, a growing number of attentions have been paid to ocean energy utilization. In this paper, a review of related researches as well as development of ocean energy in China is given. The main part of this paper is the investigation into ocean energy distribution and technology status of tidal energy, wave energy, and thermal energy, especially that of the tidal energy and wave energy. Finally, some recommendations for the future development of ocean energy in China are also provided. For further research in this field and development of ocean energy utilization in China, this review can be taken as reference.