在线离子对固相萃取预富集系统分析水样中的烷基苯磺酸盐

采用在线离子对固相萃取法富集测定生活废水中阴离子表面活性剂十二烷基苯磺酸钠.电动分析系统由1个电渗泵和5个电磁切换阀组成,计算机控制泵运作和阀切换.在萃取柱和检测器之间用改进的气液分离器除去洗脱液中气泡.实验对离子对试剂和固相萃取条件进行了优化.结果表明,在样品溶液中加入0.5 mmol/L四丁基溴化铵、采样体积15 mL、用0.80 mL/min萃取保留,2.0 mL/min吸入80 %乙腈洗脱液15 s,再以1.65 mL/min洗脱时,结果最佳.方法检出限为10 μg/L,线性范围0.030～1.00 mg/L,富集倍数65,相对标准偏差3.7 %,回收率90.6%～98.0%.

石英微米晶粒电泳微柱的制备及其电泳分离

研究了内径2mm石英管填充均匀石英微米晶粒的电泳微柱制备及其电泳分离的可行性。石英微米晶粒用水热法合成。含30%甲醇的1.5mmol/LNa2HPO4为电泳缓冲液(pH11.5),对无需衍生的色氨酸、苯丙氨酸和酪氨酸进行了微柱电泳分离和紫外吸收检测。检出限分别为0.038、0.21和0.20μmol/L;色氨酸的分离效率为4.4×104塔板数/m,电泳微柱的样品容量达到35μL,且有较好的分离重现性。对未填充石英微粒,填充平均粒度360μm石英砂和长9μm石英微米晶粒的电泳微柱的热效应进行了讨论。实验结果表明,在电泳微柱中填充石英微米晶粒可抑制大柱径电泳的热效应,增大样品容量,提高检测灵敏度。此微柱电泳技术可作为现场、实时和便携式电动流动全分析系统的高效分离手段,适合大体积和低浓度样品分析。

On-Line Broken-Bar Fault Diagnosis System of Induction Motor

Induction motor faults including mechanical and electrical faults are reviewed.The fault diagnosis methods are summarized.To analyze the influence of stator current,torque,speed and rotor current on faulted bars,a time-stepping transient finite element(FE)model of induction motor with bars faulted is created in this paper.With wavelet package analysis method and FFT method, the simulation result of finite element is analyzed.Based on the simulation analysis,the on-line fault diagnosis system of induction motor with bars faulted is developed.With the speed of broken bars motor changed from 1 478 r/min to 1 445 r/min,the FFT power spectra and the wavelet package decoupling factors are given.The comparison result shows that the on-line diagnosis system can detect broken-bar fault efficiently.

Similarity theory based method for MEMS dynamics analysis

A new method for MEMS dynamics analysis is presented,ased on the similarity theory. With this method, two systems' similarities can be captured in terms of physics quantities/governed-equations amongst different energy fields, and then the unknown dynamic characteristics of one of the systems can be analyzed according to the similar ones of the other system. The probability to establish a pair of similar systems among MEMS and other energy systems is also discussed based on the equivalent between mechanics and electrics, and then the feasibility of applying this method is proven by an example, in which the squeezed damping force in MEMS and the current of its equivalent circuit established by this method are compared.

Dynamics analysis of planar armored cable motion in deep-sea ROV system

The armored cable used in a deep-sea remotely operated vehicle(ROV) may undergo large displacement motion when subjected to dynamic actions of ship heave motion and ocean current. A novel geometrically exact finite element model for two-dimensional dynamic analysis of armored cable is presented. This model accounts for the geometric nonlinearities of large displacement of the armored cable, and effects of axial load and bending stiffness. The governing equations are derived by consistent linearization and finite element discretization of the total weak form of the armored cable system, and solved by the Newmark time integration method. To make the solution procedure avoid falling into the local extreme points, a simple adaptive stepping strategy is proposed. The presented model is validated via actual measured data. Results for dynamic configurations, motion and tension of both ends of the armored cable, and resonance-zone are presented for two numerical cases, including the dynamic analysis under the case of only ship heave motion and the case of joint action of ship heave motion and ocean current. The dynamics analysis can provide important reference for the design or product selection of the armored cable in a deep-sea ROV system so as to improve the safety of its marine operation under the sea state of 4 or above.

Electromechanical dynamics analysis and simulation on rollforming equipment with both sides variable cross-section

Electromechanical dynamics analysis and simulation on a rollforming equipment with both sides variable cross-section are discussed in this study.The system includes mechanical parts and electromagnetism parts,and it is a strongly coupled electromechanical system.Based on a virtual work principle and given power,generalized forces of this system are obtained.By using Lagrange-Maxwell equations,a model of electromechanical dynamics is established.Differential equations of two-phase winding on d-q axis are obtained by Park transformation,which comes from three-phase winding equations on the A-B-C axis.This system is solved with the 4th order Runge-Kutta's method,and discrete solutions of all variables are obtained.Finally,by using Matlab language,the system is simulated.The results show that the proposed method works very well.

Method of analyzing vibration characteristics of armature system of hermetically sealed electromagnetic relay

Published research is minimal on vibration characteristics of hermetically sealed electromagnetic relay (EMR) ex- posed to mechanical environment. The vibration characteristics of armature system, link contact system with electromagnetic system will cause EMR malfunction. The nonlinear dynamics model of armature systems was studied by considering electro- magnetic attraction force and opposite mechanical force in this paper. Angular displacements of armature under different sinu- soidal vibration conditions are solved in order to obtain the failure mode result from armature system. Vibration tests showed the presented analyzing method is suitable for EMR. The conclusions are instructive for increasing vibration resistance of armature systems of EMR, and are significant for reliability design of switch apparatus.

Research and practice of designing hydro/ photovoltaic hybrid power system in microgrid

Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.

Electrodynamic Tethered Deorbit System Dynamics and Performance Analysis

Electrodynamic tethered deorbit technology is a novel way to remove abandoned spacecrafts like upper stages or unusable satellites. This paper investigates and analyses the deorbit performance and mission applicability of the electrodynamic tethered system. To do so, the electrodynamic tethered deorbit dynamics with multi-perturbation is firstly formulated, where the Earth magnetic field, the atmospheric drag, and the Earth oblateness effect are considered. Then, the key system parameters, including payload mass, tether length and tether type, are analyzed by numerical simulations to investigate their influences on the deorbit performance and to give the setting principles for choosing system parameters. Based on this and given an appropriate group of system parameters, numerical simulations are undertaken to study the impact of the mission parameters, including orbit height and orbit inclination, and thus to investigate the mission applicability of the electrodynamic tethered deorbit technology.

Power-optimal encoding for low-power address bus

This paper presented a novel bus encoding method to reduce the switching activity on address buses and hence reduce power dissipation. Dynamic-sorting encoding(DSE) method reduces the power dissipation of address bus based on the dynamic reordering of the modified offset address bus lines. This method reorders the ten least significant bits of offset address according to the range of offset address, and the optimal sorting pattern is transmitted through the high bits of address bus without the need for redundant bus lines. The experimental results by using an instruction set simulator and SPEC2000 benchmarks show that DSE method can reduce signal transitions on the address bus by 88.2%, and the actual overhead of the encoder circuit is estimated after encoder is designed and synthesized in 0.18-μm CMOS technology. The results show that DSE method outperforms the low-power encoding schemes presented in the past.

Electric Parameter Measurement System Based on Virtual Instrument

In this paper, virtual instnnnent technology is applied in the development of an electric parameter measta＇ement system for mobile power stations. Virtual inset technology is used to lmasure and analyze electric parameters of mobile power stations. The whole measurement system is mmpmed of computer, data acquisition card and LabView virtual instnnnent platform. It can be used to monitor, record, and analyze electric parameters of sinusoidal alternating ciroait These parameters include voltage, effective value of ctaxent, phase differences, power, and etc. Experimental results show that this virtual measuring device satisfy the requirement of mobile power station montoring anti dynamic property analysis. Hardware and software design of the system will be discussed in detail.

Steady-State Performance Analysis of Brushless DC Propulsion Motor

The brushless DC motor can be used in the marine electric propulsion system for its excellent control characteristics and large thrust. In order to estimate the operating performances of the brushless DC motor for the high-power shipping during the design stage, the steady-state analysis is as important as the dynamic analysis generally. A mathematical model of the brushless DC propulsion motor is established according to the state-space method for the dynamic and steady-state performance analysis. The state-space mathematical model is a set of linear differential equations, so the steady-state currents of the armature windings can be gained directly by the symmetrical boundary conditions and the eigenvalues of the system matrix. The steady-state simulation results are compared with the dynamic ones to validate the correctness of this eigenvector method.