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This paper presents a transfer learning-based approach for induction motor fault diagnosis, where the Transfer principal component analysis (TPCA) is proposed to improve diagnostic performance of the induction motors under various working conditions. TPCA is developed to minimize the distribution difference between training and testing data by mapping cross-domain data into a shared latent space in which domain difference can be reduced. The trained model can achieve a good performance in testing data by using the learned features consisting of common latent principal components. Experimental results show that the proposed approach outperforms traditional machine learning techniques and can diagnose induction motor fault under various working conditions effectively.

Recently, the study of analog optical computing raised renewed interest due to its natural advantages of parallel, high speed and low energy consumption over conventional digital counterpart, particularly in applications of big data and high-throughput image processing. The emergence of metamaterials or metasurfaces in the last decades offered unprecedented opportunities to arbitrarily manipulate the light waves within subwavelength scale. Metamaterials and metasurfaces with freely controlled optical properties have accelerated the progress of wave-based analog computing and are emerging as a practical, easy-integration platform for optical analog computing. In this review, the recent progress of metamaterial-based spatial analog optical computing is briefly reviewed. We first survey the implementation of classical mathematical operations followed by two fundamental approaches (metasurface approach and Green’s function approach). Then, we discuss recent developments based on different physical mechanisms and the classical optical simulating of quantum algorithms are investigated, which may lead to a new way for high-efficiency signal processing by exploiting quantum behaviors. The challenges and future opportunities in the booming research field are discussed.

Weak fault signals are always embedded in mass vibration noise in many gear systems, thus making difficulty in gear fault diagnosis. In order to extract weak fault signals, a new multi-scale-based multi-fractal analysis (MMA) method is introduced in this paper, which is based on classical multi-fractal detrended fluctuation analysis (MFDFA) framework. Firstly, the Hurst surface features are utilized to describe the characteristics with multifractal of the vibration signal, which have been proved to be sensitive to the dynamical responses of the various gear faults. Secondly, a moving fitting window is added to the MFDFA framework to sweep through all the range of the scales, and then obtain final multi-scale features, whose purpose is to magnify those features in some important scales and weaken the rest scales. In addition, other techniques, such as the distance-based feature selection and the random forest (RF) classifier, are also introduced into the gearbox fault diagnosis procedure to verify the effectiveness of extracted features for differentiating various gear states. Experiments using the Qianpeng testbed (QT) prove that the MMA method can effectively extract weak signals, and has higher diagnostic accuracy than other algorithms, such as empirical mode decomposition (EMD), wavelet transform (WT), and classical MFDFA.

Introduction: This protocol is for a meta analysis that aims to systematically review the diagnostic value of anti-hepatitis B virus in serum tested by the enzyme linked immunosorbent assay in patients with hepatitis B. Methods and analysis: The following electronic databases will be searched from inception to Mar 2021: PubMed, Web of Science, ScienceDirect, EMBASE, MEDLINE, Springer, China National Knowledge Infrastructure, Chinese Biomedical Literature Database, VIP Chinese Science and Technology Periodical Database, and Wanfang Database. All study about enzyme linked immunosorbent assay reagents have been published at home and abroad to diagnose hepatitis B virus will be included. MetaDisc 1.4 soft will used to calculate pooled effect size in sensitivity, specifi city, likelihood ratio, diagnostic odds ratio and summary receiver operating characteristic curve, and area under the curve as well. Ethics and dissemination: Formal ethical approval is not required, as the data are not individualized. The findings of this systematic review will be disseminated in a peer-reviewed publication and/or presented at relevant conferences. Registration number: INPLASY2020100051.

Based on 3GR model, the relationships between energy consumption, economic effect and technical effect of countries at different stage of development (developed, developing and the least developed countries) was figured out. Comparing the equivalent value of GREC, GREO and GREI during the period from 1996 to 2013, the diverse development laws in different kinds of countries was found. The following conclusions were obtained: (1) based on 3GR model, there is a liner relationship between GREC and GREO or GREI and an inverse relationship between GREI and GREO when the equivalent value of (1+GREOi) or (1+GREIi) or (1+GRECi) is a constant. (2) The equivalent value of GREO are in the following orders, developed countries < developing countries < the least developed countries, while that of GREI have the opposite orders. The orders of the equivalent value of GREC are developed countries, the least developed countries and developing countries from small to large. The least developed countries own the largest potential to realize further development whether in economic expansion, technical innovation or in optimize industrial structure while these potential in developed countries are the smallest and in developing countries are at the middle level; the development in developing countries shows the most growth going forward. (3) The change in energy consumption is codetermined by EO effect, EI effect and their interactive effect. EO effect shows the leading position among the three effects, especially in developing countries and the least developed countries. In developed countries, EC change, EO effect and EI effect are both change in a tight range. While in developing countries and the least developed countries, these ranges are rather large.

Three main ways of how renewable energy is currently used in rural China are described in detail: biomass energy, solar energy and small hydro-power. The difficulties faced in their promotion are analyzed, such as lack of policy, lack of technical personnel, single financing channels and inadequate research efforts. Some constructive suggestions are provided, which have important theoretical significance and practical value for developing renewable energy in rural China.

In machines and mechanisms, most of the clearance joints are designed to operate with lubricant fluid, which is an effective way of ensuring better performance of the mechanical systems. The differently located lubricated joints interact with each other, influencing the total performances of the mechanical system. In this study, a numerical coupling model for the dynamics and lubrication analyses of the multibody system with multiple lubricated clearance joints is established. This approach couples the dynamics model of the multibody system with the lubrication models of translational and revolute clearance joints. The dynamics model is established by the Lagrange’s method, while The lubrication models are solved using the finite element method. The hydrodynamic forces built up by the lubricant fluid are evaluated from the motion states of the system and then input into dynamics model of the multibody system. Finally, the proposed approach is applied to a four-stroke gasoline engine with the lubricated piston skirt-liner subsystem and lubricated bearing at the big end of the connecting rod. Published version

Biomass energy as a renewable energy increasingly attracts global attention. An in-depth applied research was made on biomass energy for cooking in China's rural areas in this paper. And a novel biomass semi-gasification technology was proposed. This technology does not produce tar which causes serious environmental pollution compared with the biomass gasification technology, and has higher efficiency than the biomass direct combustion technology. This technology has a strong theoretical and practical significance in optimizing the rural energy structure, improving the rural ecological environment, and improving the production and living quality of the farmers in China.

Dynamic stress-strain states in Voronoi honeycombs are investigated by using cell-based finite element models. Two different loading scenarios are considered: the high-constant-velocity compression and the direct impact. The 2D local engineering strain fields are calculated. According to the feature of shock front propagation, the 1D distribution of local engineering strain in the loading direction is deduced from the 2D strain fields, which provide evidences of the existence of discontinuities at shock front in cellular materials and thus enhance the basis of the continuum-based shock models. A method to quantitatively clarify the local stress-strain states ahead of and behind the shock front is developed. The results show that the dynamic stress-strain states in the densification stage obtained from both loading scenarios are different from the quasi-static stress-strain relation. The stress ahead of the shock front obtained from the high-constant-velocity compression scenario is slightly smaller than the quasi-static yield stress, but that obtained from the direct impact scenario is larger than the quasi-static yield stress. The possible mechanisms of deformation and wave propagation are explored.

Purpose: To introduce the novel effective Y-shaped silicon stent for treating canalicular laceration. Methods: Fifty-four canalicular laceration cases (54 eyes) underwent the lacrimal surgery using the novel Y-shaped silicon stents were collected, and the stents were removed 3 months after surgery. All cases were followed up for 12 months. The operability of stenting and removing the stent were assessed. The data we collected during each follow-up are: stent position and integrity, aesthetic results, the discomfort, the symptom of epiphora, the patency of lacrimal passage, complications, and patient’s satisfaction. Results: The stenting time was 14.3±5.8 min and the time of removing it was 1.8±0.5 min. Both of the operability of stenting and removing were accessed to be easy in more than 94.4% cases. All stents were in position and integrated. 51 cases (94.4%) had no problems on aesthetic results. Three patients (5.4%) complained about the discomfort. Two cases (3.7%) had the symptom of epiphora, which were obstructed after removing the stents. Fifty-two cases (96.3%) were with patent canaliculus and satisfied with the surgery and symptom improvement. Only 5 cases (9.3%) had complications. Conclusion: The novel Y-shaped silicon stent is an effective stent for treating canalicular laceration.

With the development of our society, the proportion of the accidents caused by human behavior (e.g. human behavior and organizational behavior) is increasing nowadays. “Human Error” has gradually become the focus of the research. Though researched and confirmed by the experts home and abroad, the significance of being the manager still get overlooked easily in reality. Taking into the consideration this situation, for which authors propose “Condition Theory” and to analyze the importance of the manager in the security events by telling examples to reach the conclusion that the role of manager has been the core effect in the security investigation and prevention.

Mine ventilation system which was the important constituent of coal mining system ensured the safety production as critical measures. Construction and quantification of evaluation index system for mine ventilation system was the basis and standard of comprehensive evaluation of system's defect. This paper began with hazard factors which caused ventilation accident, investigated the direct and indirect reasons, and then carried on a qualitative analysis of Fault Tree. According to analysis results, an evaluation index system of ventilation system was constructed and the index was also quantified by use of AHP. Since that existing index system was improved and supplemented, it is supposed to improve the operational capability and rationality of daily management as well as safety evaluation of mine ventilation system.

Network of measurement and control is now converging with network of information tightly more and more, which improves the development of network-distributed measurement and control technology. And networked sensors are important unit in networked measurement and control system. This paper applied Session Initiation Protocol (SIP) to networked sensors system aimed for a kind of unified IEEE 1451 NCAP model of networked sensors using SIP as the interface. We analyzed the features of SIP and sensor network interface, presented a frame of networked sensor based on SIP according to IEEE1451 sensor standards, and studied on-line register of networked sensor based on SIP. Devices supported by SIP in distributed control system can communicate easily with IP-based information network, and can also provide conveniently multimedia service. SIP and P2P SIP are worthy of deep research for networked sensor system.

With the rapid development of science and technology of intelligent transportation, Frequency Modulated Continuous Wave (FMCW) radar sensor has been widely used in automotive auxiliary driving. This paper presents a method to obtain parameters of obstacles ahead a vehicle. Firstly, the signal processing is applied to detect and analyze the moving obstacle to get its range, speed and Doppler shift. Then, a spatial model is set up for the height detection of the obstacle. Finally the feasibility of the introduced method is demonstrated through simulation by using FMCW radar sensors which are mounted on a vehicle. This method of obstacle detection may be applied on safety driving assistant.

A small forest-ball was manufactured and calibrated using CMM F25. An industrial CT called Metrotom1500 was calibrated by the small forest-ball and another big forest-ball produced by Carl Zeiss. These two forest-balls were separately measured at two different magnifications of the industrial CT, and the measurement results could meet the maximum permissible error of Metrotom1500.

A rhombus-shaped microstrip meander-line slow-wave structure is proposed for use in a low voltage, wide bandwidth, moderate power and high efficiency millimeter-wave traveling-wave tube. The structure is evolved from the original V-shaped microstrip meander-line slow-wave structure. Compared with the conventional slow-wave structure, it is a kind of planar structure, whose fabrication can be easily realized by utilizing the technology of 2-D micro-fabrication. Whats more, the structure can realize beam-wave interaction with sheet electron beam, and no additional electron beam channel is needed. The electromagnetic characteristics and the interaction between the sheet electron beam and slow wave in the structure are obtained by utilizing the electromagnetic simulation software HFSS and the particle-in-cell code in CST Particle Studio, respectively. Our calculations indicate that, at a beam voltage of 7 kV and a beam current of 90 mA, the traveling wave tube based on the structure is capable of delivering several tens of watts output power with an interaction efficiency of 14.3％ and a transient 3 dB bandwidth of 18 GHz(ranging from 132 GHz to 150 GHz)

In the field of optical imaging, the conventional imaging resolution is about 200 nm due to the diffraction limit. The higher resolution is urgently needed for further developing scientific research. Therefore, how to break through this limitation to acquire high quality and high resolution image has become a hot research topic. The microspheres with the size of tens of micrometers exhibit the ability to improve the imaging resolution of the conventional optical microscope by locating them directly on the sample surface. Due to its simplicity, the microsphere optical nanoscope technology is widely studied. This paper introduces the research background of the optical microscope and the research progress of microsphere optical nanoscope technology. At the same time, approaches to adjusting the photonic nanojet generated by the microspheres by fabricating concentric ringing, central mask, and surface coating of microspheres are reviewed. The possible reasons for this improved resolution are discussed. The applications and development of the microsphere ultra-microscopic technology in the future are discussed.

The advantages and disadvantages of Static Synchronous Compensator (STATCOM) between centralized configuration and distributed configuration is proposed. Through the analysis of an application case, the distributed configuration of STATCOM can be more effectively provided the load bus voltage support compared with centralized configuration base on the same capacity. It ensures the stability of the end of the load bus voltage, thereby increasing the voltage level of the hub substation.

During grasping the underwater object, friction condition of fingers and object is variable, and forces imposed on the object are very complex too. It's difficult for autonomous operation to grasp the underwater object, and the operation requires a full tactile sensing. Therefore the methods are presented to extract the feature of touch and slide sensing from the output data of four component finger force sensors, aiming at the experimental research for underwater operation. According to contact model of fingers, we choose four component finger force sensors based on strain gauges. Employing fusing output data of finger force sensors installed on claw, it is very convenient for obtaining reliably touching, sliding and grasping forces.

With the development of power electronics technology, more and more power electronic facilities have been used in power system. The valve stack of series SCRs is the key to realize the dynamic VAr compensation with thyristor-switched-capacitor at medium voltage distribution network. This paper presents a firing technology as a solution for MV TSC. TSC with "transient-free" switching process is analyzed and zero-cross gating technology is required. Optical fiber and series zero-cross optoisolators triac drivers are adopted as parts of triggering system to solve the problems of isolating, zero-cross detection, gating energy, etc.. The performance of this triggering system was tested by field experiments, which showed satisfied effectiveness and certified its validity to be used as the executive component of TSC

As more attention on human beings, developing an effective communication interface connecting the human brain to computer becomes an active research area in recent years. Until now, no efficient device can record the entire procedure of intrinsic human behavior information, including acquiring, transmitting, processing and outputting. In this paper, we offer a system which consists of computer and F-tablet, the later can acquire the kinematics and kinetics information of human handwriting. Joined with human beings, a vision-brain-hand to computer (VBH-C) interaction system is presented. In this human-in-the-loop-testing system, human beings acquire image, voice or text from computer by eyes or ears then write them down. As a closed-loop feedback portion, the designed F-Tablet acquires strokes of pen-up and pen-down, velocity and acceleration of pen-tip, three dimension forces of pen-plate contacting point and shape of character etc. The core part of the system, named as F-Tablet, is introduced which is able to acquire the trajectory and three-axis forces directly and simultaneously of pen-tip. A simple test will be done to judge the movements and forces controlling ability of different ages with the help of the system. Comparing with other brain-computer interface (BCI), VBH-C interface can offer more information, especially as a closed-loop and information feedback, it is easier for human decision pattern identification.

The re-entrant double-staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube. This structure has a wide bandwidth, a moderate interaction impedance, and excellent thermal dissipation properties, as well as easy fabrication. A well-matched waveguide coupler is proposed for the structure. Combining the design of attenuators, a full-scale three-dimensional circuit model for the V-band coupled-cavity travelingwave tube is constructed. The electromagnetic characteristics and the beam–wave interaction of this structure are investigated. The beam current is set to be 100 mA, and the cathode voltage is tuned from 16.8 kV to 15.8 kV. The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz. The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%, respectively.

A watt-class backward wave oscillator is proposed, using the concise sine waveguide slow-wave structure combined with a pencil electron beam to operate at 220 GHz. Firstly, the dispersion curve of the sine waveguide is calculated, then, the oscillation frequency and operating voltage of the device are predicted and the circuit transmission loss is calculated. Finally, the particle-in-cell simulation method is used to forecast its radiation performance. The results show that this novel backward wave oscillator can produce over 1-W continuous wave power output in a frequency range from 210 GHz to 230 GHz. Therefore, it will be considered as a very promising high-power millimeter-wave to terahertz-wave radiation source.

Staggered double vane slow wave structure (SWS) and sheet electron beam are employed to investigate a 140 GHz high power traveling wave tube. Numerical calculation of eigenmode shows that the SWS has a good characteristic of dispersion and interaction impedance. The transition structure, input/output coupler and concentrated attenuator are especially proposed for the circuit to ensure that the tube will work well. Particle-in-cell simulation results demonstrate that the traveling wave tube can provide over 300 W of peak power in a frequency range of 132-152 GHz with a maximum of 546 W and a corresponding gain of 37.37 dB at 138 GHz assuming a beam power to be 5.115 kW and input power to be 0.1 W. The output power of the tube can exceed 440 W in a frequency range of 128-152 GHz with a corresponding interaction efficiency of over 8.6% when the input powers range from 0.027 W to 0.46 W. Such a traveling wave tube has a great significance and a potential application in high power short millimeter wave field.

A novel slow-wave structure, i.e., an open-style dielectric-lined azimuthally periodic circular waveguide (open-style DLAP-CW) which can be applied to millimeter wave traveling-wave tube, is proposed. The hot dispersion characteristics are derived by the self-consistent relativistic field theory. And the electron beam interaction in the novel slow-wave structure (SWS) is analyzed in a linear frame. The linear gain characteristics of the DLAP-CW is studied analytically for dimensions of the improved SWS and the parameters of the electron beam. The results illustrate that selecting the appropriate dimensions of the metal rods can improve the small-signal gain. Finally, a comparison of the small-signal gain of this structure with a close-style DLAP-CW is made, and the results validate that the novel SWS has an advantage over the close-style DLAP-CW in gain with little influence on the bandwidth, which can potentially improve electron efficiency in the beam wave interaction. The research in this paper will also be a foundation of the theory for open-style dielectric-lined azimuthally periodic circular waveguide traveling-wave tube.