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Both silicone gel and quercetin are effective in scar treatment but have different action mechanisms. Quercetin is mainly applied in the gel form and can lead to poor adhesion of silicone gel sheet; therefore, they cannot be combined in clinical use. In this study, a silicone gel sheet that releases quercetin in a sustained manner for 48 hours was successfully developed. Four round scars (Ø: 1 cm) were made in the ears of New Zealand albino rabbits (n = 10). After scar healing, the rabbits were divided into four groups: blank control group with no treatment, silicone gel sheet group with dressing change every 2 days, quercetin group with dressing change three times daily, and combination treatment group with dressing change every 2 days. Scar assessment was performed 3 months later. Transepidermal water loss showed no difference between the combination treatment group and the silicone gel sheet group, but was lower than that in the quercetin group and the blank control group. Immunohistochemistry of CD 31 and proliferating cell nuclear antigen showed the following results: combination treatment group < silicone gel sheet group = quercetin group < blank control group. Polymerase chain reaction results showed that the expression of type-I and type-III collagen in the combination treatment group and the quercetin group was significantly lower than that in the other two groups. Thus, quercetin-modified silicone gel sheet combines the advantages of the two treatments and is more effective at inhibiting cell proliferation in scar tissue than either of the two treatments alone.

Lameness has a considerable influence on the welfare and health of dairy cows. Many attempts have been made to develop automatic lameness detection systems using computer vision technology. However, these detection methods are easily affected by the characteristics of individual cows, resulting in inaccurate detection of lameness. Therefore, this study explores an individualized lameness detection method for dairy cattle based on the supporting phase using computer vision. This approach is applied to eliminate the influence of the characteristics of individual cows and to detect lame cows and lame hooves. In this paper, the correlation coefficient between lameness and the supporting phase is calculated, a lameness detection algorithm based on the supporting phase is proposed, and the accuracy of the algorithm is verified. Additionally, the reliability of this method using computer vision technology is verified based on deep learning. One hundred naturally walking cows are selected from video data for analysis. The results show that the correlation between lameness and the supporting phase was 0.864; 96% of cows were correctly classified, and 93% of lame hooves were correctly detected using the supporting phase-based lameness detection algorithm. The mean average precision is 87.0%, and the number of frames per second is 83.3 when the Receptive Field Block Net Single Shot Detector deep learning network was used to detect the locations of cow hooves in the video. The results show that the supporting phase-based lameness detection method proposed in this paper can be used for the detection and classification of cow lameness and the detection of lame hooves with high accuracy. This approach eliminates the influence of individual cow characteristics and could be integrated into an automatic detection system and widely applied for the detection of cow lameness.

Sialolithiasis is the common disease of salivary glands. The majority of sialoliths occur in the submandibular gland or the Wharton’s duct. The length of sialolith usually measures from 1 to

This study aimed to improve the conventional rat burn wound model and to validate its utility. In total, 60 Sprague-Dawley rats were divided equally into the control and experimental groups. Altogether, 60 burn wound models with zones of stasis were created in each group. Gross visual assessments of the burn wounds were performed at 0 h, 24 h, and 48 h after burn creation. The rates of necrosis in the zones of stasis were calculated, and the blood flow from the wounds was examined. Wound tissues were collected 48 h after the burn and subjected to hematoxylin and eosin staining to determine whether the models were successfully established. The model success rates were calculated. The success rate of the burn wound models was significantly different between the control group and the experimental group (93.33% [56/60] vs. 100%; P=0.042). The Cronbach's alpha values and the respective correlation coefficients indicated that the stability of the zones of stasis in the models on the 2 sides of the spine was higher in the experimental group than in the control group. The standard deviations of the rate of necrosis, blood flow, and density of necrotic cells and apoptosis cell density, and inflammatory factor content in the zones of stasis were smaller in the experimental group than in the control group at 48 h after model construction. This suggested that the stability of repeated procedures was higher in the experimental group than in the control group. The novel device for creating burns in animal models facilitated the effective creation of zones of stasis for rat burn wound models. Both the model success rate and stability were higher compared with the conventional model construction method. In addition, the use of the novel device can better align with the requirements of self-controlled studies. This article is protected by copyright. All rights reserved.

The abundant geothermal energy in hot dry rock (HDR) formations is an attractive renewable energy resource with great potential. China will develop its first HDR geothermal formation in the Gonghe Basin. HDR is a hard and low-permeability granite containing very few fluids. Development requires fluids to cyclically flow between injection and production wells to extract geothermal energy in the artificial heat transfer zone. Hydraulic fracturing is the main technology for creating flow paths. But few studies have investigated fractures in HDR geothermal formations. This paper investigated fractures as flow paths in HDR geothermal formations during hydraulic fracturing. Hydraulic fractures were simulated using a custom true-triaxial hydraulic fracturing test system in a realistic formation environment, in which a scaled wellbore was used that was built in outcrop granite rock from the Gonghe Basin. Fracture creation in granite was investigated via experiments, as well as influence factors, and what experience could be achieved. This study can be used to design and evaluate hydraulic fracturing projects in potential HDR geothermal formations.

To improve the efficiency of the wind power generation, this article proposes an active disturbance rejection controller (ADRC) based MPPT strategy, and establishes a LabVIEW FPGA platform based hardware-in-the-loop (HIL) test system. Firstly, the configuration, operation principle, mathematical model and maximum power point tracking (MPPT) control strategy of the wind power generation are analyzed. According to the angular speed tracking motion equation of the wind turbine, the ADRC based MPPT strategy is designed. Secondly, the real-time simulation model of wind speed, wind turbine and PMSG, as well as MPPT rapid control prototype (RCP) are developed by using PXI-FPGA architecture on the LabVIEW RT real-time operation platform. Then, by building a power converter and connecting it to the PXI-FPGA real-time operation platform, the HIL test system is established. Finally, the HIL real-time simulation tests are conducted with various wind speed conditions. The results not only prove the correctness of ADRC based MPPT strategy, but also demonstrate that the HIL system is an efficient tool for application in wind power generation development.

Background: There have been few studies on large-scale samples regarding natural killer/T-cell lymphoma (NKTCL) in children and adolescents for the low incidence of NKTCL in this age group. The clinical, histopathological and molecular features of 22 young people with NKTCL were evaluated. The aim of the present study was to provide a better understanding of the clinicopathological aspects of this rare entity of lymphoma.Results: There were 15 male and 7 female patients (male/female, 2.14:1) with a median age of 15 years. The results revealed that the nasal site was the most involved region while non-nasal sites were observed in 27.3% out of all cases, and exhibited histopathological and immunohistochemical features similar to the cases in adults. Seven (36.8%) out of all the 19 patients during the follow-up died of the disease, and the median follow‑up period was 44 months. Moreover, patients treated with radiotherapy/chemotherapy showed significantly inferior OS compared with the untreated patients. High mutation frequencies were detected including KMT2C (5/5), MST1 (5/5), HLA-A (3/5) and BCL11A (3/5), which involved in modifications, tumor suppression and immune surveillance. Conclusion: NKTCL in children and adolescents is a rare type of T/NK cell neoplasms. This disease is difficult to distinguish from other EBV-related disorders in young people. Furthermore, active treatment is necessary after the diagnosis of NKTCL is confirmed.

The aerodynamic characteristics of Darrieus vertical axis wind turbines (VAWTs) are affected by several geometrical parameters. Airfoil shape is one of the important factors which have not been received enough attention in the past, compared to other parameters such as solidity, number of blades, chord length, rotor diameter, pitch angle and aspect ratio. In this paper, four airfoils with varying maximum thickness (12%, 15%, 18% and 21%) are investigated by calculating the aerodynamic characteristics of Darrieus VAWTs using computational fluid dynamics technology. The power and torque characteristics, as well as their flow field characteristics, are analyzed. The results indicate that the power coefficient follows a trend of CP_NACA 0018 > CP_NACA 0015 > CP_NACA 0021 > CP_NACA 0012 below an optimum TSR, while it increases with the decrease in airfoil maximum thickness beyond the optimum TSR. The optimum TSR and operational zone also increase with the decrease in airfoil maximum thickness. An optimized airfoil thickness is determined to be between 15 and 18% for a relatively high power coefficient and appropriate optimum TSR, as well as a wider operational zone and a high efficiency band. Moreover, the airfoil maximum thickness influences the strength and region of the vorticity, as well as the interactions between blades and shed vortex, being the main reason for the observed differences in instantaneous torque coefficient. The vorticity of NACA 0015 model is weaker and smaller than that of NACA 0021 model when TSR is 2.0.

As the manufacturing industry is heading toward the fourth industrial revolution, smart manufacturing is born at the right moment. By integrating new information technologies, such as the Internet of Things, the cyber-physical system (CPS), big data, and artificial intelligence, smart manufacturing has endowed the factories and shop floors with much intelligence, which is characterized by the organic cooperation among workers, machines, unmanufactured products, and other physical assets. In this situation, endowing these smart physical assets with self-X intelligence and autonomy to make manufacturing resources allocation decisions autonomously has been a vital problem that needs prompt solutions. To solve this problem, this paper deals with training a reasonable knowledge model from the historical shop floor data using a hidden Markov model (HMM) theory. In this model, the unmanufactured product's machining feature/process flow is considered as an observation sequence and the corresponding smart manufacturing resources (SMRs) sequence is considered as a hidden state sequence. The solving method to train the HMM-based knowledge model for autonomous manufacturing resources allocation (A-MRA) is further described in a step-by-step manner. Thereafter, a demonstrative case is studied to verify the proposed model and method. First, 123 pairs of historical data (i.e., process flow and SMR sequence) are used to learn the HMM-based knowledge model and another 5 pairs of historical data are used to test the feasibility and accuracy of the proposed model. The results show that only three elements (total $5\times 9$ elements) in the predicted SMR sequences are different from those in the historical SMR sequences, and the average vector angle between the five predicted and historical SMR sequences is 11.68°, which is relatively low considering that only nine elements exists in each SMR sequence.

Background: Epigenetic regulation plays vital roles in the oncogenesis and treatment of diffuse large B-cell lymphoma (DLBCL). The H3K9me3-specific histone methyltransferase SUV39H1 is an epigenetic gene that promotes the progression of a variety of malignancies. However, the roles of SUV39H1 in DLBCL remain unclear.Methods: Initially, the Oncomine, Cancer Cell Line Encyclopedia (CCLE), UALCAN and Gene Expression Profiling Interactive Analysis (GEPIA) databases were searched to explore the expression of SUV39H1 in DLBCL. The clinical parameters and pathological sections of 61 successive patients, including 47 cases of DLBCL and 14 cases of reactive lymphoid hyperplasia, were collected from January 2019 to November 2020. Immunohistochemistry was conducted to verify the results of the database search. Finally, relevant parameters and pathological results were combined to analyze the expression of SUV39H1.Results: We found that the expression of SUV39H1 in DLBCL tissues was higher than that in normal and other cancer tissues (PP=0.037), suggesting that patients with high SUV39H1 expression are less likely to develop tumors over 7.5 cm in size. Regarding survival, the group with high SUV39H1 expression had a lower survival rate than the group with low SUV39H1 expression in terms of 10-year disease-free survival (DFS) according to the database analyses (P=0.035). However, SUV39H1 was revealed as an independent predictor of overall survival (OS) and progression-free survival (PFS) in patients from both databases and our hospital (P>0.05).Conclusion: SUV39H1 expression is higher in DLBCL tissues than in normal and other cancer tissues, indicating that DLBCL patients may not develop bulky tumors over follow-up and suggesting that SUV39H1 might serve not only as a predictive factor in the clinic but also as a target for the epigenetic therapy of DLBCL.

Compared to traditional cameras, light field imaging can additionally record the direction of incoming light. Based on this, light fields can be represented in focus stacks that focus at different depths and all-in-focus images. The refocusing information of focal stacks can provide supplementary information for saliency detection. In this paper, we propose a novel multi-generator adversarial network for saliency detection that consists of a cascaded multi-generator and a discriminator. The multi-generator extract saliency features from all-in-focus images and focal stacks. Besides, we set the predicted map multiplied by the all-in-focus image as the input of the discriminator. With this multiplication, we can preserve color and texture information of the salient objects, and reduce the computational cost. We conduct experiments on three public datasets. Compared with existing methods, our method achieves competitive results.

Under the circumstance of soft fractured surrounding rock with high geo-stress, the support technology of tunnel has become a major challenge. Traditional I-shaped steel and bar lattice girder, which cross-sections are often designed to be left-right symmetrical, may have insufficient strength and stiffness. Based on the concept of symmetry, a new support technology of spatial steel tubular grid (SSTG) arch is designed with high strength and large stiffness. In order to clarify the mechanical properties and failure mechanism of SSTG arch used as primary support, through laboratory and numerical experiments, this paper carries out the bending tests for the circumferential joint of SSTG arch components combined with the excavation tunnel project of Panyu Square Station in Guangzhou, and the analyses of the ultimate bearing capacity, deflection displacement, failure modes, and stress&ndash, strain evolution laws of joint components are conducted in detail. The results show that during the whole process of loading, the arch components have experienced elastic growth stage, plastic development stage, and final failure stage. The average ultimate bending capacity of SSTG arches is 340.5 kN&middot, m, and the joint opening is 13.9 mm. The joint form of high-strength bolt + rigid flange plate proposed in the paper has reasonable stress state and high safety redundancy, which can bear the load of surrounding rock effectively, and ensure the safety in tunnel construction. The research results could provide a theoretical basis for the design and application of SSTG arch support in related projects.

Welding of copper was conducted using a single-mode fiber laser rotated at a high speed by a galvano scanner. The rotation diameter and frequency were changed to investigate the effect of the beam rotation on the welding quality. The rotation diameter changed from 0.3 to 1.0 mm and the rotation frequency changed from 77 to 285 Hz. The weld depth obtained with scanning is smaller than that obtained without scanning. The weld depth decreases as rotation frequency increases, regardless of the rotation diameter. The bead width obtained with scanning is larger than that obtained without scanning because of the larger laser radiation area. In the welding there is an unscanned area, based on the relationship between laser scanning conditions and welding speed, that makes the weld depth periodic. It was found that welding geometry can be controlled by adjusting scanning parameters. Spatter and surface voids decrease as rotation frequency and diameter increase. It was confirmed a scanning speed over 500 mm/s suppressed large spatter and surface voids.

This paper numerically investigates the effects of airfoil leading edge radius on the aerodynamic characteristics of H-rotor Darrieus vertical axis wind turbine (VAWT). 10 modified airfoils are generated by changing the leading edge radius of the base NACA 0015 airfoil from 1%c to 9%c, respectively. A 2D unsteady Computational Fluid Dynamics (CFD) model is established and validated with the previously published experimental data. The power, torque, and flow field characteristics of the rotors are analyzed. The results indicate that the maximum and minimum power coefficient at the optimum tip speed ratio (TSR) are obtained for the LE-5%c and LE-1%c model, respectively. The best aerodynamic characteristics are determined by the LE-5%c model below the optimum TSR and the LE-3%c model beyond the optimum TSR. The torque characteristics and pressure distribution for the single blades with different airfoil leading edge radius show an obvious difference in the upwind region and a very small difference in the downwind region. Moreover, the airfoil leading edge radius influences the strength, region, and diffusion rate of the vortices, being the main reason for the observed differences in instantaneous torque coefficient and power coefficient. The vortices of the LE-1%c model are stronger, larger, and diffuse slower than those of the LE-2%c and LE-5%c model at the optimum TSR.

Waterflooding is currently one of the most common and mature oil and gas development methods. However, when oil and gas fields enters the medium or high water-cut period, there is still a large amount of residual oil remaining untapped while residual oil characteristics and distribution could be complicated. Micromodel method is considered as a novel experimental method for studying residual oil characteristics and waterflooding. Unlike conventional core flooding, visualization of the whole process can be realized through micromodels. In this work, three different flooding rates were used to simulate the waterflooding process via micromodels. Consequently, oil recovery rates and residual oil distribution were obtained. It was observed that higher waterflooding rate increased the oil recovery. When the flooding rate was large, dispersed residual oil was observed after waterflooding. When the rate was small, residual oil exhibited more complicated configurations. For the trapped residual oil in the dead end pores in hydrophilic rock matrix, increasing the flooding rate or the viscosity of displacing phase could be beneficial to dislodge the residual oil.

Fault diagnosis based on deep learning has become a hot research topic because of the successful application of deep learning in other fields. Due to variable operating conditions and a harsh operating environment, it is extremely difficult to effectively diagnose some typical faults of diesel engines. When operating conditions and environmental factors change, the performance of deep learning models also become extremely unstable. In order to solve these problems, this paper proposes a novel deep learning model, called multi-branch convolutional neural networks (MBCNNs) with an integrated cross-entropy. MBCNN can be embedded in the proposed model and simultaneously equipped with four auxiliary classifiers. The proposed model is trained on two different datasets separately, which consist of six diesel engine faults. The trained network model was compared with other methods to prove the superiority of this network model. Meanwhile, by adding Gaussian white noise, the performance of the MBCNN in different noise environments is investigated. The final results show that the MBCNN with integrated cross-entropy can effectively diagnose different diesel engine faults under variable operating conditions.

The computer vision technique has been rapidly adopted in cow lameness detection research due to its noncontact characteristic and moderate price. This paper attempted to summarize the research progress of computer vision in the detection of lameness. Computer vision lameness detection systems are not popular on farms, and the accuracy and applicability still need to be improved. This paper discusses the problems and development prospects of this technique from three aspects: detection methods, verification methods and application implementation. The paper aims to provide the reader with a summary of the literature and the latest advances in the field of computer vision detection of lameness in dairy cows.

Energy Internet is a new hot topic in the research of industry and academia at home and abroad. It is also the development direction of the energy industry, and it is possible to innovate the way of human life. The paper summarized the concept and connotation by surveying the domestic and international development of the Internet of Energy. The information technology architecture of the Internet of Energy is reviewed from the perspective of the integration of energy system and information technology. This article described the characteristics of power line carrier communication, and analyzed the role and status of power line carrier communication technology in the Internet of Energy. The challenges and opportunities that power line carrier communication faces in the Internet of Energy are analyzed. In the end, this paper discussed the future development of Internet of Energy. Through the “Internet +”technology though, it will integrate advanced information technology and energy systems, coordinate multi-energy networks, innovate energy system operation modes, promote industrial upgrading, and generate new economic growth points.

A novel tri-band bandpass filter (BPF) is proposed by using cross-coupled stepped impedance resonators (SIRs), which can operate at 2.4 GHz, 3.5 GHz and 5.25 GHz respectively. In engineering application, it is suitable for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX). In addition, the passband of this filter can be easily controlled by changing the electrical parameters of the resonators. So it is helpful to the selection of passband in engineering applications. For in-depth analysis, the equivalent circuit of the filter is also proposed. At last, it shows that the measured results agree well with the simulated results. The insertion loss of the filter within each passband is less than 1.9 dB, meanwhile two transmission zeros are obtained which can be able to meet the engineering requirements.

Background: Striae distensae (SD) are common and aesthetically undesirable dermal lesions. The aim of this study is to comprehensively evaluate the effectiveness of different therapies in treating striae distensae using network meta-analysis.

Under mesophilic conditions (37 °C), a bench-scale experiment of dry fermentation start-up using kitchen waste was conducted in a fed-batch single phase reactor over a period of 40 days. The results showed that (1) comparing biogas production, efficiencies, and methane concentrations, three apparent different stages emerged: adaption, growth, and stability; (2) in adaption and growth stages, daily biogas production was 0–0.2 L/day and 0.2–0.4 L/day, respectively, and the concentration of methane in the biogas was 22.91% and 48.79%, respectively, with a biodegradation rate of approximately 34.72% in the adaption phase and 27.60% during the growth phase; (3) in the stability stage, the biogas production efficiency attained the maximal level and stabilized at approximately 0.6–0.4 L/day and the concentration of methane was 54.32%. Furthermore, the pH fell to 4.15, and the concentration of chemical oxygen demand increased from 51.139 to 119.295 mg/ml.

Mini-sized steel pipe pile technology is more used to foundation reinforcement, underpinning and isolation under the condition of construction site or space is limited. This paper discusses the mechanism and construction technology of mini-sized steel pipe grouting pile foundation underpinning technology. This paper shows how to effectively solve the problems of existing buildings foundation reinforcement construction through the actual engineering examples. This paper also analysis of the feasibility and validity of the mini-sized steel pipe grouting pile foundation underpinning technology, the research results can provide a practical and feasible construction scheme for similar engineering.

Classification is one of the most important tasks in real world with the intention of finding the underlying patterns of the data and making use of the found patterns. Other than considering lots of parameters that may influence the classification model accuracy, the influence of the feature selections has been rarely discussed. SHAP (SHapley Additive exPlanation) value is a novel ensemble learning measurement that is the unique consistent and locally accurate attribution value. Its applications to feature selection are not mentioned in the literature. In this paper, we compare the prediction accuracy of several feature selection techniques on a set of Polish companies. We show that new feature selection method based on the SHAP values is superior (not worse) to other widely used prediction methods.

Because of its advantageous aerodynamic performance, the vertical-axis wind turbine (VAWT) has gained more and more attention. This paper studies the vibration characteristic of the VAWT main spindle, and presents a mechanical and electromechanical coordination vibration suppression method for the VAWT main spindle. The proposed method can measure main spindle current vibration intensity in real-time. And when the main spindle vibration intensity exceeds preset critical control threshold value, the method can use both the on-line intelligent analysis decision and the mechanical and electromechanical coordinated controller to suppress the main spindle vibration, as well as to make the VAWT maintain mechanical stability. At the same time, the method can ensure the VAWT meets maximum wind energy capture efficiency as far as possible.

For overcoming the disadvantages of wide range wind power perturbation and model parameter uncertainties, a novel maximum power point tracking (MPPT) controller for permanent magnet synchronous generator (PMSG) based vertical axis wind power generation system is developed using back-stepping control method. The MPPT controller adopts wind turbine's optimum rotational speed tracking algorithm, and the wind turbine's dynamic aerodynamic mechanical torque is estimated by an extended state observer (ESO). According to the back-stepping controller design approach, virtual control signals and Lyapunov functions are constructed step by step. By employing Lyapunov stability theorem, back-stepping control law for each subsystem is worked out, thus, the global asymptotical stability for the overall closed-loop system that all virtual control signals involved is guaranteed. The back-stepping control system is simulated using Matlab/Simulink software, which is compared with a traditional PID control system. The simulation results verify the correctness and effectiveness of the back-stepping controller.

The welding distortion of thin plate was selected as research subject, which causes loss of dimensional control, structural integrity and increases fabrication costs for straightening. To study the characteristic of the welding distortion on thin plate structures, experiments were conducted. The test model was a thin plate stiffened structure and a large twisting distortion was observed. The welding distortion of the same structure was analyzed as a large deformation problem using a thermal elastic plastic FEM and an elastic FEM based on the concept of inherent deformation. The computed results by both methods showed the twisting distortion which is a typical buckling type deformation and the magnitude of this distortion agreed well with the experimental measurement.

This paper focuses on an intelligent MPPT (maximum power point tracking) algorithm for permanent magnet vertical-axis direct-drive wind turbine systems. The relationship between generator speed and buck convert’s duty ratio is analyzed. then, the output and the speed of wind turbine are controlled by convert’s duty ratio. In this way an intelligent MPPT algorithm, the different step length is given in different directions, is used to this system. At last, the system is simulated by software, and the simulation results indicates that compared with the conventional MPPT strategy, the rapidity and the stability are increased by intelligent MPPT algorithm.

Based on the disciplines theory such as the mechanics and electromagnetics, this paper presents three kinds of electromaglev linear feed unit, with the help of the 3D modeling software Solidworks and large general purpose finite element analysis software ANSYS. The statics analysis on workbenches of the three kinds of electromaglev linear feed unit are made by using of ANSYS, then the results are analyzed and compared. It can be identified as the conclusion that, the structural stiffness on workbenches of the three kinds of magnetic linear feed unit can basically meets the requirement, and all of them can be selected as the needed structural design. But the four-L separately suspended and oriented type electromaglev linear feed unit has the better structure stiffness, and take the weight, cost, load capacity and dynamic characteristics and other factors into account, we preferred to choose the workbench design of the four-L-pillar separately suspended and oriented type electromaglev linear feed unit.

The transfer function of the BUCK converter is proposed by using the state-space average method. The lead-lag network is used to optimize the stability of the closed-loop BUCK system. And the stability of the system has been greatly improved. At last the simulation model of the system is founded by using the Matlab software. Compared with the results of the simulation of open-loop and closed-loop system, the conclusion can be reached that the stability of the after- compensator system is greatly improved.

The structural and working principle of a kind of maglev linear feed unit for CNC engraving and milling machine tools are presented, and its mathematical model is analyzed, then its model of vibration is established in this paper. The modal analysis is made, the natural frequency is calculated with its vibration models, and the influence on the natural frequency of electromagnetic levitation bearing unit, which is caused by stiffness and damping coefficients of electromagnetic levitation bearing, is analyzed respectively by means of ANSYS software. The calculation and analysis presented in this paper can help us design the structure of the maglev linear feed unit for CNC engraving and milling machine tools, and can also establish a solid foundation for further etailed dynamics analysis.

Vertical axis wind turbine (VAWT) plays one of the important roles in wind power equipments. When joining the magnetic levitation technology, the VAWTs can effectively reduce the friction torque to improve startup performance and increase the power coefficient. At the same time, the mechanical vibration can be reduced, and its actual functioning time can be extended. In this paper, the structure, working principle and mathematical model were introduced respectively with an intention to present the magnetic supporting structure of a VAWT. Then the self adaptive integral-type sliding mode control (AISMC) was offered and designed. Compared with convention-al PID control, the simulations show that the system under the AISMC control has a better dynamic response and robust characteristic.

This paper investigates the modeling and decoupling control of grid-connected voltage source inverter (GC-VSI) for wind energy conversion system (WECS) applications. Firstly, the typical configuration and operation principle of the direct-driven grid-connected WECS are analyzed. Then, by means of input-output modeling method and instantaneous active power theory, a time domain mathematical model of the GC-VSI is set up. Besides, in order to resolve the GC-VSI active current and reactive current cross-coupling nonlinear control problem, a vector decoupling control method for the GC-VSI firing pulse generation is deduced in the dq synchronous rotating coordinates. The proposed decoupling control method can realize the active power and reactive power of the GC-VSI injected into the grid are regulated independently. Finally, the performance of the proposed GC-VSI system is evaluated by using MATLAB/Simulink simulation.

In this paper, a nonlinear dynamic decoupling controller is proposed for the permanent magnet linear synchronous motor (PMLSM) servo system to improve dynamic operating performance. Firstly, the reversibility of the PMLSM mathematical model is analyzed, and it is proved that the system is reversible. Then an inverse system method is applied to the PMLSM servo system, and it is decoupled into a linear velocity subsystem and a linear current subsystem based on the α-th order inverse system method. Considering the both ideal linear subsystems are sensitive to parameter disturbances and various disturbances, a variable rate reaching law approach based subsystem sliding mode controller for higher system stability and robustness is proposed. Finally, simulation results are provided to demonstrate the effectiveness of the proposed control method.

In order to eliminate the chattering phenomena caused by conventional sliding mode control (SMC) method in magnetic bearing system control, this paper proposes a variable rate reaching law approach based sliding mode controller to achieve higher system stability and robustness. In this control law, system states’ normal numbers are brought in to automatic adjust the gain of the switching control part of SMC. The controller output amplitude of chattering can be progressively damped, and the system will converge to zero asymptotically. The system stability is proved by Laypunov theory, and the prerequisite of control law parameters design is deduced out. Simulation results show that the proposed SMC control method has effectiveness in dynamic suspension position tracking performance and obtaining system robustness.

In the fields of numerical control machine, robot etc, vector control system of permanent magnet synchronous motor (PMSM) has widely application prospects. Proportion integration (PI) adjustment block, coordinate transformation block, space vector pulse width module (SVPWM) block and the simulation model of the whole system are built in MATLAB/SIMULINK according to the mathematical model, SVPWM technique and vector control theory of PMSM. The simulation results show that stator winding triphase current can run smoothly, speed and output torque can be accurately follow the given value. The results provide the basis for further research of the performance of the PMSM control system.

This paper presents a theoretical analysis and experimental evaluation of the switched reluctance generator (SRG) for off-grid variable-speed wind energy applications. The detailed model, control parameters and operational characteristics of the SRG as well as variable-speed wind turbine are discussed. In order to drive the wind energy conversion system (WECS) to the point of maximum aerodynamic efficiency, a SRG power output feedback control strategy which optimized angle position-current chopping control cooperating PI regulator is proposed. The control strategy is also demonstrated by means of Matlab/Simulink. Moreover, an experimental test system is set up, which a cage induction machine is used to emulate the variable-speed wind turbine. The experimental results validate the proposed control strategy and confirm the SRG performance.

In this paper the single mode condition of silicon-on-insulator (SOI) rib waveguide with large cross section is investigated based on the effective index method (EIM) by using numerical computation and analytical derivation with the consideration of the polarization effects. A polarized single-mode condition for SOI rib waveguide with large cross section is presented, the results from analytical derivation are highly concordant with that from numerical computation. For the vertical single-mode condition, the deviations between HE and EH modes correlate oppositely with the total rib height of rib waveguide, and the critical rib height ratio gradually approaches but never equals to 0.5 with the increase of the total rib height. There, HE mode and EH mode are commonly known as quasi-transverse-electric (TE) mode and quasi-transverse-magnetic (TM) mode respectively. The deviation of the critical rib width between HE and EH modes for the lateral single-mode condition is relatively small, which is a function of the rib height ratio but irrelevant to the total rib height for the specified index profile. The fact that the total rib height, index profile, and polarization of modes have effects on the single-mode condition of SOI rib waveguide with large cross section was demonstrated in this work, which was not discussed in the previous works. The results in this work can give guidance to design, simulation and fabrication of SOI rib waveguide with large cross section in practical applications.

In this paper, a novel extended state observer (ESO) based integral sliding model control (ISMC) approach is proposed to achieve maximum power point tracking (MPPT) for direct-driven permanent magnet synchronous generator (PMSG) variable speed wind energy conversion systems (VS-WECS). The proposed control approach adopts optimum tip speed ratio tracking scheme to realize maximum wind energy capture. Considering strong nonlinear and uncertainty features of VS-WECS, the ISMC is developed on the basis of the rotor angular speed tracking model. The sliding mode surface function consists of the integral term of the rotor angular speed tracking error, which ensures the rotor angular speed tracking without error at stable state. To eliminate the undesired chattering phenomena aroused from the sign function in the sliding mode control law, an ESO is designed to estimate the wind turbine aerodynamic torque. Using torque estimate feedback technique, the gain of sign function has the capability of self-adjustment according to the fluctuation of wind speed. Simulation results show that the proposed control approach has better tracking performance compared with that of conventional PI regulator.

This paper proposes a novel maximum power point tracking (MPPT) control strategy for variable speed wind turbine system using the optimal torque sliding mode control technique. In this strategy, the generator optimal torque tracking error and its integral are selected as system state variables, and a dynamic sliding mode controller is designed to improve the wind energy capture efficiency and shorten MPPT response time for variable wind speed working condition. The actual control input signal is formed from a first-order integral operation of the original sliding mode control input signal, which makes the generator actual control input reference current signal continuous and smoothing. It also contributes greatly to chattering attenuation and avoiding large fluctuations of the generator output power. The simulation results for a permanent magnet synchronous generator (PMSG) based wind turbine system have proved the validity of the proposed control strategy.

Focal point position control is significant in deep penetration laser beam welding because it is apt to change during welding due to some fluctuating factors, such as the non-planar workpiece, welding distortion and thermal focusing. This work describes the design of a double closed-loop control of the focal point position for CO2 laser beam welding. A photodiode sensor (PS) and a plasma charge sensor (PCS) are simultaneously utilized to detect the optical emission and plasma charge current in welding. It is found that the PCS signal could be used to control the nozzle–workpiece distance based on the decrease of PCS signal intensity with increasing nozzle–workpiece distance. The PS signal could be used to control the focal point position by using PS signal variation with focal point position. Therefore, a system for double closed-loop controlling the focal point position has been set up, using the PCS signal to control the nozzle–workpiece distance and the PS signal to control the focal point position. The experimental results with a non-planar workpiece show that the double closed-loop control of the focal point position not only automatically follows the contours of the workpiece surface, but also controls the focal point position constant by compensating the effect of thermal focusing.

Compared with lasers with the wavelength of 1030nm∼1080nm, including Nd:YAG, Fiber and Disk lasers, one of the advantages of using 515 nm green laser is its higher absorption for many metals, except aluminum. Thus deeper penetration depth is expected for welding of these metals. In this paper, the basic phenomena and penetration properties of 515nm green laser was investigated. A 515nm green laser with the maximum power of 300W and a 1070nm-1080nm fiber laser with the maximum power of 2000W were separately used for conducting welding experiments. The materials used in welding were pure copper and 304-Type stainless steels. A high-speed camera was used to observe the behavior of the plume and weld pool during welding. The results show that the green laser can produce extremely deep and narrow weld bead. The mechanism of welding keyhole with 515nm green laser is discussed as well.Compared with lasers with the wavelength of 1030nm∼1080nm, including Nd:YAG, Fiber and Disk lasers, one of the advantages of using 515 nm green laser is its higher absorption for many metals, except aluminum. Thus deeper penetration depth is expected for welding of these metals. In this paper, the basic phenomena and penetration properties of 515nm green laser was investigated. A 515nm green laser with the maximum power of 300W and a 1070nm-1080nm fiber laser with the maximum power of 2000W were separately used for conducting welding experiments. The materials used in welding were pure copper and 304-Type stainless steels. A high-speed camera was used to observe the behavior of the plume and weld pool during welding. The results show that the green laser can produce extremely deep and narrow weld bead. The mechanism of welding keyhole with 515nm green laser is discussed as well.

A coordinated nonlinear controller of static synchronous compensator (STATCOM) and generator excitation are designed according to the direct feedback linearization (DFL) theory and the T-S type fuzzy sliding mode variable-structure control (FSMC) theory. The proposed coordinated controller can improve both the power angle stability of generator and the voltage behavior at the STATCOM location. It is designed based on local measurements and possess good robustness. The simulation studies indicate the proposed coordinated controller can improve the accuracy of voltage control and strengthen the stability of power systems.

H.264 (MPEG4 AVC) is a new video coding standard jointly developed by ITU-T and ISO MPEG. H.264 derives most of its coding efficiency improvements from motion estimation which, on the other hand, has greatly increased the computational complexity of the CODEC, so many fast motion estimation algorithms have been proposed, such as MVFAST, HEXBS and so on. In this paper, we propose a fast mode decision method which can greatly reduce the computational complexity of subpixel motion estimation and speed up the encoder.

H.264 is a new recommendation for moving picture coding proposed by JVT. In this standard, full pixel and sub-pixel motion estimation are the most important parts. The unequal-arm adaptive rood pattern search (APRS-3) algorithm has shown a good performance on search speed-up. In this paper, we propose an improved algorithm called APRS-4 which applies an early termination technology on APRS-3 by using adaptive threshold. This early termination technology is also applied on sub-pixel motion estimation, and a new fast sub-pixel motion estimation algorithm is proposed which uses the motion vector information of the neighbor blocks. Experimental results show that both algorithms have achieved a good speed-up ratio. Compared with full-pixel motion estimation, our new algorithm could keep image quality well with almost the same bit rate.

The area of visual prosthesis by electrically stimulating the neural tissue of the blind person is more and more attractive with the development of electrode array and biological technology. Processing the images captured by the camera is the first step in the whole project. We use a new algorithm to get the accurate edge of color images. The result is better than that obtained through some edge operators like Canny, Soble. Then, we use simple methods to segment the image into regions that are based on gray level images of objects we are most interested in. Finally, we integrate the results from the two steps above. These methods are simple and have low computational complexity that can be used in real time process and in the volume-limited chip. The result is good in visual prostheses and also adapt to pixelized vision in later steps.

We investigate blind adaptive multiuser detection with interference rejection in direct sequence code division multiple access (DS-CDMA) cellular communication systems. A general approach is presented, which is independent of the information transmission rate of the systems. For multiuser detection, the DS-CDMA channel is first modeled into a multiple-input multiple-output (MIMO) signal model framework. Then, based on a decision feedback equalizer (DFE), multiuser information symbols can be recovered without any prior knowledge of the channel and the users' signature waveforms (including the desired user's signature waveform). Simulation results illustrate good performance of the proposed method, and the proposed method can be effectively used in both low-rate and high-rate DS-CDMA systems, which provides it a broader use in practical scenarios.

We propose a new video coding scheme based on four improvements. (1) Half pixel precision is used for the overlapped motion compensation. (2) Region wavelet decomposition is only applied to the significant region in the prediction error image (displacement frame difference, DFD). (3) Zerotree is used for representation of the significant region wavelet coefficients. (4) A quantization model based on the human visual system (HVS) have been used for intraframe coding. Simulation results show that some coding gain has been reached compared to the conventional wavelet coder.

A novel video coding scheme based on the blocking regional wavelet transform and overlapped motion compensation is researched in this paper. Several new or improved algorithms are proposed. The high-energy regions of interframe predicted difference are first detected using a hierarchical sliding-window region forming algorithm. The regional border is processed to reduce ringing-effects. Wavelet decomposition and quantization are carried out only for these regions. A quantization model based on HVS spatiality-frequency and time-frequency features is used in the coding algorithm. An improved single-pass scanned zero-tree is employed to represent quantized wavelet coefficients. This scheme reduces the bit rate by about 36%-51% or gets a distinct improvement in decoding video quality by cutting down ringing-effects at the same bit rate compared with traditional wavelet-based coding algorithms. Simulation results show acceptable image quality for CIF resolution at low bit-rate and very low bit-rate.

We construct a low-bit rate multimedia communication system (LBMCS) and propose a new fast motion estimation algorithm which guarantees the implementation of a software-based H.263 codec. Based on this system we implement some practical functions such as remote monitor, videophone, audio recording, video recording, facsimile (FAX) and white board. Besides discussing the hardware structure and software frameworks of the system, we place the emphasis on the efficient implementation of the H.263 codec where the improvement in half-pel estimation is mentioned, and a novel search algorithm SSS (synthetical switch search) is expatiated on. Simulation results show that SSS is rather better than the common-used search algorithm, the TSS (three step search).