烟腔无电机叶轮空气放大式抽油烟机的机理

标准空气放大器制成的烟腔无电机叶轮抽油烟机,虽能克服现有抽油烟机烟腔内的电机叶轮吸油结垢和甩出油垢之弊端,但空气放大器本体的气隙易受油垢堵塞。通过在本体增开油槽和油孔,能自防气隙堵塞,具有附壁效应。附壁效应的机理是:输入的压缩空气从气隙冲向本体气腔上端乃至上方,形成空心状负压区,能强烈抽吸本体底端下方的油烟,形成实心气柱,从而实现抽吸油烟量远大于压缩空气输入量。

烟腔无电机叶轮的空气放大式抽油烟机之机理

标准空气放大器制成的烟腔无电机叶轮抽油烟机,虽能克服现有抽油烟机烟腔内的电机叶轮吸油结垢之缺陷和甩出油垢之弊端,但空气放大器本体的气隙易受油垢堵塞,而在本体增开油槽和油孔,即能自防气隙堵塞。该抽油烟机涉及附壁效应,而附壁效应在此的正解是:输入的压缩空气从气隙冲向本体的气腔上端乃至上方,形成空心状负压区,能强烈抽吸本体底端下方的油烟,形成实心气柱,从而实现抽吸油烟量远大于压缩空气输入量。

无电机转速可调自清洗过滤器的设计

无电机转速可调全自动自清洗过滤器是一种国内外研究最多的过滤器设备,文章研究了无电机转速可调过滤器驱动系统的工作原理和结构特性,自主研发了一种无电机转速可调吸污式全自动自清洗过滤器。经过试验,该设备不需安装电机和外接电源,便可实现实时清洗时不间断供水,耗水量小,零件互换性强,装配简单,安装方便,智能化水平高,成本低,具有较好的市场应用前景。

新型脱气器研发理论探讨

脱气器是综合录井仪和气测录井仪的重要设备,脱气器的脱气效率和稳定性直接影响录井气测分析结果,进而影响对油气层的识别和解释。通过对现用电动脱气器优缺点的分析,提出一种全新理念的脱气器,并详细分析了这种脱气器的结构,原理及优势:(1)脱气效率高,利于发现薄层气;(2)脱气量充足,稳定、无管线堵塞;(3)安装位置合理,无逸散气流失;(4)无电机,结构简单,节约成本,易于维修;(5)安全性能更高。基于以上特点使其有着很高的推广应用价值。

STRATEGY AND IMPLEMENTATION FOR HIGH-SPEED TORQUE ENHANCEMENT OF BRUSHLESS DC MOTOR

Serious commutation lag occurs when a Brushless DC Motor(BLDCM) operates at high speeds,and this leads to torque decline with ripple.In this paper,an advanced conduction control scheme is proposed which can accelerate the commutation and enhance the torque production remarkably.Besides,an on line adjusting algorithm based on the Golden Section Method is adopted to search the optimal advanced conduction angle.Simulation and experimental results verify the feasibility and effectivity of the scheme proposed.

Anti-reverse rotation startup method for sensorless brushless DC motor

In order to start up the brushless DC motor （BLDCM） without reverse rotation and smoothly switch the running state of the motor, a novel startup and smoothly switching method for a sensodess BLDCM is presented. Based on the saturation effect of the stator iron, six short voltage pulses are applied to determine the initial rotor position and the rotor can be found within 60°. After that, a series of short and long voltage pulses are used to accelerate the motor and the variation of the response current is utilized to detect the rotor position dynamically. When the motor reaches a certain speed at which the back-electromotive force （EMF） method can be applied, all the power devices are turned off and the running state of the motor is smoothly switched at the moment determined by the relationship between the terminal voltage waveform and the commutation phases. The experimental results verify the feasibility and validity of the proposed method.

EFFECTIVE DOUBLE LOOP CONTROL FOR A SQUARE WAVE BRUSHLESS DC MOTOR

A new type of brushless DC motor has been developed by using a square wave rare earth permanent magnet synchronous motor with its double loop control circuit. The double loop control scheme of the drive system yields a combination of desired characteristics including simplified control structure, small ripple torque, high speed accuracy, wide operating speed range, and fast dynamic response. Experimental results confirm excellent characteristics of the motor.

Integrated design of brushless motor drive and control system for robot joints

To meet the requirements of high performance, low cost, and easy operation of the robot, a brushless motor drive and control system for the robot joint is designed, including CAN bus, WPF upper host computer development, and magnetic encoders, and other sensors, in which the STM32 F103 chip is used as the main control chip, and the DRV8323 is a brushless motor drive chip. The principle of field-oriented control(FOC) brushless motor drive is elaborated.Meanwhile, the drive and control system design is completed from both hardware and software aspects. Finally, the PID algorithm is used for the closed-loop speed test of the robot joint. The experimental result shows that the designed robot joints and control system run smoothly and reliably, have the characteristics of modularization and miniaturization, and are suitable for the control of micro-service robots and manipulators.

Geochemistry of Iron,Sulfur and Related Heavy Metals in Metal-Polluted Taihu Lake Sediments

To understand the geochemical characteristics of iron and sulfur and the extent of iron-sulfide minerals influencing heavy metal behaviour in metal-polluted sediments of Talhu Lake, two sites, in Meiliang Bay （ML） and Wuli Lake （WL）, were selected to study the fractionation of iron, sulfur and related heavy metals. There were relatively high concentrations of Fe^2＋ and low concentrations of total S^2- in porewaters, indicating that conditions in these sediments favored iron reduction. The concentrations of acid volatile sulfides in sediments were 1.9-9.6 μmol g^-1 at ML and 1.0-11.7 μmool g^-1 at WL, both in the range of values detected in unpolluted lakes. Pyrite-S was 10.2-49.4 μmol g^-1 at ML and 10.3- 33.0 μmol g^-1 at WL, accounting for more than 69% of the reduced inorganic sulfur at both sites. The low degree of sulphidization （〈 14%） and pyritization （〈 10%） indicate that sulfate may be the limiting factor for pyrite formation. The extractability of Mn, Cu, Pb, Zn, Ni, and Cr in sediments all suggest that sulfides are not the major binding phase for these metals during early diagenesis. Sulfur may play a modest role in the geochemistry of iron and traced metals in the sediments.

Novel high torque bearingless two-sided rotary ultrasonic motor

Applications are limited at present because the currently available ultrasonic motors (USMs) do not provide suffi-ciently high torque and power. The conventional travelling-wave USM needs the bearing to support, which required lubricant. To solve the above problem, a bearingless travelling-wave USM is designed. First, a novel structure of the two-sided USM consisting of a two-sided teeth stator and two disk-type rotors is designed. And the excitation principle of the two-sided travelling-wave USM is analyzed. Then, using ANSYS software, we set up the model of the stator to predict the excitation frequency and modal response of the stator. The shape of the vibration mode was obtained. Last, the load characteristics of the USM are measured using ex-perimental method. The maximum stall torque and the no-load speed were obtained. The results showed that the characteristics of the two-sided USM are better than those of the conventional one-sided USM.

Simulation of Dynamic Electromagnetic Interference Environment for Unmanned Aerial Vehicle Data Link

In order to test the anti-interference ability of an Unmanned Aerial Vehicle(UAV) data link in a complex electromagnetic environment,a method for simulating the dynamic electromagnetic interference of an indoor wireless environment is proposed.This method can estimate the relational degree between the actual face of an UAV data link in an interface environment and the simulation scenarios in an anechoic chamber by using the Grey Relational Analysis(GRA) theory.The dynamic drive of the microwave instrument produces a real-time corresponding interference signal and realises scene mapping.The experimental results show that the maximal correlation between the interference signal in the real scene and the angular domain of the radiation antenna in the anechoic chamber is 0.959 3.Further,the relational degree of the Signal-toInterference Ratio(SIR) of the UAV at its reception terminal indoors and in the anechoic chamber is 0.996 8,and the time of instrument drive is only approximately 10 μs.All of the above illustrates that this method can achieve a simulation close to a real field dynamic electromagnetic interference signal of an indoor UAV data link.

Modelling of modern automotive petrol engine performance using Support Vector Machines

Modern automotive petrol engine performance is significantly affected by effective tune-up. Current practice of engine tune-up relies on the experience of the automotive engineer, and tune-up is usually done by trial-and-error method and then the vehicle engine is run on the dynamometer to show the actual engine performance. Obviously the current practice involves a large amount of time and money, and then may even fail to tune up the engine optimally because a formal performance model of the engine has not been determined yet. With an emerging technique, Support Vector Machines (SVM), the approximate per- formance model of a petrol vehicle engine can be determined by training the sample engine performance data acquired from the dynamometer. The number of dynamometer tests for an engine tune-up can therefore be reduced because the estimated engine performance model can replace the dynamometer tests to a certain extent. In this paper, the construction, validation and accuracy of the model are discussed. The study showed that the predicted results agree well with the actual test results. To illustrate the significance of the SVM methodology, the results were also compared with that regressed using multilayer feedforward neural networks.

Reliable energy-efficient routing with novel route update in wireless sensor networks

In this paper we introduce a novel energy-aware routing protocol REPU (reliable, efficient with path update), which provides reliability and energy efficiency in data delivery. REPU utilizes the residual energy available in the nodes and the re-ceived signal strength of the nodes to identify the best possible route to the destination. Reliability is achieved by selecting a number of intermediate nodes as waypoints and the route is divided into smaller segments by the waypoints. One distinct ad-vantage of this model is that when a node on the route moves out or fails, instead of discarding the whole original route, only the two waypoint nodes of the broken segment are used to find a new path. REPU outperforms traditional schemes by establishing an energy-efficient path and also takes care of efficient route maintenance. Simulation results show that this routing scheme achieves much higher performance than the classical routing protocols, even in the presence of high node density, and overcomes simul-taneous packet forwarding.

NOVEL SENSORLESS VECTOR CONTROL SYSTEM OF INDUCTION MACHINE BASED ON FLUX OBSERVER IN FIELD WEAKENING

A speed-sensorless vector control system for induction machines （IMs）is presented, According to the vector control theory of IMs, the rotor flux is estimated based on a flux observer,and the speed is estimated through the method of q-axis rotor flux converging on zero with proportional integral regulator, A 0.75 kW,50 Hz,two-pole induction machine was used in the simulation and experimental verification, The simulation model was constructed in Matlab. A series of tests were performed in the field weakening region, for both no-load and loaded operation. The estimated speed tracks the actual speed well in the based speed region and field weakening region （ 1 per unit value to 4 per unit value）. The small estimation error of residual speed is due to the existence of slip.

Error analysis and distribution of the driving mechanism for large spherical radio telescope active reflector

In order to reduce the cost,3-PRS mechanism is introduced into the application of supporting theactive reflector unit of large radio telescope.The kinematic model of 3-PRS mechanism with rotationaljoint errors is derived to solve the error problem in actual engineering application.Then based on the errormodel,inverse and forward kinematics are analyzed.Because the solutions can not be analytically ex-pressed,a numerical method is applied.Afterwards,the parasitic motion errors are analyzed using searchmethod and empirical formulas of the maximum parasitic motion error are put forward.Finally,the toler-ance is distributed using empirical formulas to avoid interference between adjacent reflector units.Theanalyses provide a theoretical basis for the design and installation of large radio telescope active reflector.

Improved Feistel-based ciphers for wireless sensor network security

Wireless sensor networks (WSNs) are exposed to a variety of attacks. The quality and complexity of attacks are rising day by day. The proposed work aims at showing how the complexity of modern attacks is growing accordingly, leading to a similar rise in methods of resistance. Limitations in computational and battery power in sensor nodes are constraints on the diversity of security mechanisms. We must apply only suitable mechanisms to WSN where our approach was motivated by the application of an improved Feistel scheme. The modified accelerated-cipher design uses data-dependent permutations, and can be used for fast hardware, firmware, software and WSN encryption systems. The approach presented showed that ciphers using this approach are less likely to suffer intrusion of differential cryptanalysis than currently used popular WSN ciphers like DES, Camellia and so on.

A New-style Permanent-magnet Motor with Double-stator Structure

A new-style direct drive motor with double-stator structure is proposed. The structure and principle of the permanent-magnet (PM) brushless motor are discussed. On the basis of numerical calculation, the cogging torque waveforms of the prototype motor when staggering two stators are analyzed. The method that can reduce torque ripple making use of the structure features of this motor is investigated. The results of numerical calculation and experiment indicate that designing motor with this kind of structure is a good scheme for increasing the power density.

A QoS-Aware Packet Scheduling Mechanism in Cognitive Radio Networks for Smart Grid Applications

Cognitive radio sensor network is applied to facilitate network monitoring and management, and achieves high spectrum efficiencies in smart grid. However, the conventional traffic scheduling mechanisms are hard to provide guaranteed quality of service for the secondary users. It is because that they ignore the influence of diverse transition requirements in heterogeneous traffi c. Therefore, a novel Qo S-aware packet scheduling mechanism is proposed to improve transmission quality for secondary users. In this mechanism, a Qo S-based prioritization model is established to address data classification firstly. And then, channel quality and the effect of channel switch are integrated into priority-based packet scheduling mechanism. At last, the simulation is implemented with MATLAB and OPNET. The results show that the proposed scheduling mechanism improves the transmission quality of high-priority secondary users and increase the whole system utilization by 10%.

Research of variable speed directly driven SRG wind power system position sensorless based on DFNN by FEA

A new method of switched reluctance wind power generation position sensorless based on DFNN by FEA was proposed, Through current and magnetic linkage to get the angle of SRG rotor position, the nonlinear mapping of cur- rent-magnetic linkage-angle was built, By training these sample data from FEA, the angle of SRG rotor position was replaced by the output of DFNN to achieve SRG position sensorless. Simulation results show that the error between actual rotor position and estimate rotor position is small; SRG can commutate with great accuracy; and the output voltage of SRG wind power system under variable wind speed is essentially constant.

Fast-ionic conductor Li_(2.64)(Sc_(0.9)Ti_(0.1))_(2)(PO_(4))_(3) doped PVDF-HFP hybrid gel-electrolyte for lithium ion batteries

With increasing demand on energy density of lithium-ion battery,wide electrochemical window and safety performance are the crucial request for next generation electrolyte.Gel-electrolyte as a pioneer for electrolyte solidization development aims to solve the safety and electrochemical window problems.However,low ionic conductivity and poor physical performance prohibit its further application.Herein,a fast-ionic conductor(Li_(2.64)(Sc_(0.9)Ti_(0.1))_(2)(PO_(4))_(3))(LSTP)was added into poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)base gel-electrolyte to enhance mechanical properties and ionic conductivity.Evidences reveal that LSTP was able to weaken interforce between polymer chains,which increased the ionic conductibility and decreased interface resistance during the cycling significantly.The obtained LiFePO_(4)/hybrid gel-electrolyte/Li-metal coin cell exhibited excellent rate capacity(145 mA·h/g at 1C,95 mA·h/g at 3C,28℃)which presented a potential that can be comparable with commercialized liquid electrolyte system.