多定子直线感应电机故障模式下的电流过载特性

为了提高可靠性和安全性,长初级双边直线感应电机可以采用多台初级(N 2)上下并联布置共用一个次级的结构形式。针对多定子直线感应电机,对其数学模型进行了深入研究,并基于耦合参数等效电路模型,详细分析了两定子直线感应电机输出电磁推力与输入相电流及工作转差频率之间的函数关系,得到了其单台定子因故障而退出运行,另一台定子维持输出电磁推力不变时其三相电流的过载规律。利用某两定子双边直线感应电动机原理样机进行实验,实验结果与理论分析吻合,验证了理论分析的正确性。

多定子直线感应电机模型及间接矢量控制算法

针对多台定子(N≥2)上下并联布置共用一个次级结构的多定子直线感应电机,采用电压/电流空间矢量及其向量形式建立电机等效电路模型及其控制器模型。借助于控制器模型中电机次级动子板输出的机械功率,得到多定子直线感应电机输出电磁推力的计算表达式,并推导出适用于多定子直线感应电机的间接矢量控制方程。将该模型和控制算法应用于某型轨道交通列车试验线,实验结果表明,列车启动阶段速度超调量不超过1.10%,验证了理论分析的正确性。

一种新型多定子直线型超声电机的研究

直线型超声电机具有可直接驱动、精度高、响应快、适用于真空环境等优点,但驱动力较小。为提高工作台的负载能力,该文提出并研制了一种多定子直线型超声电机。样机由两个定子和一个动子(与工作台台面相联)组成。定子是一个利用1阶纵振和2阶弯振、带双足的兰杰文振子,双足交替驱动。讨论了该电机的驱动机理,对定子的结构进行了优化设计,给出了定子、动子、工作台一体化的设计方案,并对电机的输出性能做了初步的实验研究。

多定子永磁直线同步电机绕组切换故障特性研究

针对多定子永磁直线同步电机(PMLSM)运行过程中绕组切换故障可能引起的失步问题,研究了绕组切换故障特性。在分析PMLSM推力功角特性的基础上,研究了频率对稳定运行区间的影响规律,建立了考虑出入端效应的多定子PMLSM推力模型,研究了绕组切换故障对稳定性的影响规律,利用样机进行了实验研究,得到了一台及两台绕组切换故障时,电机运行频率、运行方式对运行特性的影响规律。研究结果表明:低速PMLSM的电阻效应不能忽略,动子所受正向推力作用空间变小,负向推力作用空间增大。相同数量的绕组失电,提升运行时较易失步。失电绕组越多,剩余电机承担电流越大,越易引起失步。

超声电机多定子同步驱动技术的研究

研究多定子超声电机同步驱动技术,通过多定子同步驱动增加电机的驱动力(矩),解决目前单定子驱动电机输出功率不大的问题,并且以两个定子同步驱动为例,分别给出了采用分立元件、AVR以及DSP 3种器件设计驱动电路的方法,比较分析了各自的优缺点,并指出多定子同步驱动可有效提高电机运行的可靠性和稳定性,探讨了同步驱动技术今后的发展趋势。

M_n(~R) (a_n, f, x) Apporximation in L_p[0, l]

Generalized Bernstein-Kantorovich polynomials M_n^((k))(a_n, f, x) were introduced in the paper and their order of approximation were estimated in the L_p[0, 1]-spaces.

A Preliminary Study of Rotundine-Polyion Complex Release System

A rotundine-polyion complex(PIC)release system was prepared first by granulation of rotundine containing chitosan acetate solution and then by complexing with carboxymethyl glucomannan(CMGM)solution on the granular surface.The granules have an average diameter of 1.38-1.53 mm and the drug content reaches 62.89％.The external release tests showed T_(50) to be 45 rain and the total release time 4 h in an artificial gastric juice,while no more than 60％ of the drug was released in the same period of time in an ar- tificial intestinal fluid.The various factors affecting the external release were examined.

Power system stabilizer design using hybrid multi-objective particle swarm optimization with chaos

A novel technique for the optimal tuning of power system stabilizer (PSS) was proposed,by integrating the modified particle swarm optimization (MPSO) with the chaos (MPSOC).Firstly,a modification in the particle swarm optimization (PSO) was made by introducing passive congregation (PC).It helps each swarm member in receiving a multitude of information from other members and thus decreases the possibility of a failed attempt at detection or a meaningless search.Secondly,the MPSO and chaos were hybridized (MPSOC) to improve the global searching capability and prevent the premature convergence due to local minima.The robustness of the proposed PSS tuning technique was verified on a multi-machine power system under different operating conditions.The performance of the proposed MPSOC was compared to the MPSO,PSO and GA through eigenvalue analysis,nonlinear time-domain simulation and statistical tests.Eigenvalue analysis shows acceptable damping of the low-frequency modes and time domain simulations also show that the oscillations of synchronous machines can be rapidly damped for power systems with the proposed PSSs.The results show that the presented algorithm has a faster convergence rate with higher degree of accuracy than the GA,PSO and MPSO.

Efficient and Stable Optimization of Multi‑pass End Milling Using a Cloud Drop‑Enabled Particle Swarm Optimization Algorithm

Optimization of machining parameters is of great importance for multi-pass end milling because machining parameters adversely or positively affect the time and quality of production.This paper develops a second-order fulldiscretization method(2ndFDM)-based 3-D stability prediction model for simultaneous optimization of spindle speed,axial cutting depth and radial cutting depth.The optimal machining parameters in each pass are obtained to achieve the minimum production time comprehensive considering constraints of 3-D stability,machine tool performance,tool life and machining requirements.A cloud drop-enabled particle swarm optimization(CDPSO)algorithm is proposed to solve the developed machining parameter optimization,and 13 benchmark problems are used to evaluate CDPSO algorithm.Numerical results show that CDPSO algorithm has a certain advantage in computational cost as well as comparable search quality and robustness.A demonstrative example is provided.

Output Speed and Torque of Differential Double-Stator Swing Hydraulic Multimotors

A new type of differential double-stator swing hydraulic motor, based on double stator structure, was introduced. Compared with the traditional swing hydraulic motors, it could provide various kinds of rotational speeds and torques under the same conditions of input flow rate and pressure. The operating prindple and graphic symbols were described. The output speed and torque characters in multifarious connection modes were analyzed through single-acting differential double-stator swing hydraulic multi-motors. Then the differential connection modes and differential principles of differential double-stator swing hydraulic multi-motors were stated. Furthermore, the output speed and torque characters of double- acting and triple-acting ones in multifarious connection modes were gotten. The interaction between output torque and the displacement ratio was studied. Finally, the internal leakage that influenced the volumetric efficiency was researched. The theoretical and experimental researches show that the differential double-stutor swing hydraulic multi-motors can provide various kinds of rotational speeds and torques. Predictably, this new kind of swing hydraulic multi-motors has broad application prospects in machine tool equipments, engineering machineries, and simulation turntables.

Identification of Fucans from Four Species of Sea Cucumber by High Temperature ~1H NMR

Acidic polysaccharide, which has various biological activities, is one of the most important components of sea cucumber. In the present study, crude polysaccharide was extracted from four species of sea cucumber from three different geographical zones, Pearsonothuria graeffei(Pg) from Indo-Pacific, Holothuria vagabunda(Hv) from Norwegian Coast, Stichopus tremulu(St) from Western Indian Ocean, and Isostichopus badionotu(Ib) from Western Atlantic. The polysaccharide extract was separated and purified with a cellulose DEAE anion-exchange column to obtain corresponding sea cucumber fucans(SC-Fucs). The chemical property of these SC-Fucs, including molecular weight, monosaccharide composition and sulfate content, was determined. Their structure was compared simply with fourier infrared spectrum analyzer and identified with high temperature 1H nuclear magnetic resonance spectrum analyzer(NMR) and room temperature 13 C NMR. The results indicated that Fuc-Pg obtained from the torrid zone mainly contained 2,4-O-disulfated and non-sulfated fucose residue, whereas Fuc-Ib from the temperate zone contained non-, 2-O- and 2,4-O-disulfated fucose residue; Fuc-St from the frigid zone and Fuc-Hv from the torrid zone contained mainly non-sulfated fucose residue. The proton of SC-Fucs was better resolved via high temperature 1H NMR than via room temperature 1H NMR. The fingerprint of sea cucumber in different sea regions was established based on the index of anomer hydrogen signal in SC-Fucs. Further work will help to understand whether there exists a close relationship between the geographical area of sea cucumber and the sulfation pattern of SC-Fucs.

Determination of Transport Properties for Dilute Gas Mixtures Involving Carbon Tetrafluoride

In our previous work,we calculated transport properties of pure gaseous polyatomic carbon tetrafluoride(CF4) and five equimolar binary gas mixtures of CF4 with noble gases through inversion technique.The present work is a continuation of our studies on determining the transport properties of binary gas mixtures CF4 with some gases including three diatomic molecules CO,N2,and O2,a linear polyatomic CO2,and two non-linear polyatomic molecules SF6 and CH4.The Chapman-Enskog and Vesovic-Wakeham methods as well as inversion procedure are used to determine the viscosities,diffusivities,and thermal conductivities,which deviates from the literature values within 1%,4%,and 5%,respectively.

Quaternary phosphonium polymer-supported dual-ionically bound[Rh(CO)I_(3)]^(2-)catalyst for heterogeneous ethanol carbonylation

A single-Rh-site catalyst(Rh-TPISP)that was ionically-embedded on a P(V)quaternary phosphonium porous polymer was evaluated for heterogeneous ethanol carbonylation.The[Rh(CO)I_(3)]^(2-)unit was proposed to be the active center of Rh-TPISP for the carbonylation reaction based on detailed Rh L3-edge X-ray absorption near edge structure(XANES),X-ray photoelectron spectroscopy(XPS),and Rh extended X-ray absorption fine structure(EXAFS)analyses.As the highlight of this study,Rh-TPISP displayed distinctly higher activity for heterogeneous ethanol carbonylation than the reported catalytic systems in which[Rh(CO)_(2)I_(2)]^(-)is the traditional active center.A TOF of 350 h^(-1)was obtained for the reaction over[Rh(CO)I_(3)]^(2-),with>95%propionyl selectivity at 3.5 MPa and 468 K.No deactivation was detected during a near 1000 h running test.The more electron-rich Rh center was thought to be crucial for explaining the superior activity and selectivity of Rh-TPISP,and the formation of two ionic bonds between[Rh(CO)I_(3)]^(2-)and the cationic P(V)framework([P]^(+))of the polymer was suggested to play a key role in firmly immobilizing the active species to prevent Rh leaching.

Genetic instability in cancer tissues analyzed by random amplified polymorphic DNA PCR

OBJECTIVE: To detect DNA and chromosomes instabilities during the progression of tumors and screen new molecular markers coupled to putative or unknown oncogenes and/or tumor suppressor genes. METHODS: Five kinds of tumors, in a total of 128 specimens, were analyzed by random amplified polymorphic DNA (RAPD) PCR. Bands representing instabilities were recovered, purified, and cloned, labeled as probes for Southern and Northern blot analysis and DNA sequencing. RESULTS: Sample 5 and 3 of the gastric cancer tissues showed the highest genomic changes and the average detectability in five cancers was up to at least 40% (42.2% - 49.4%). There were significant differences in the ability of each primer to detect genomic instability, which ranged from 27% (primer 8) to 68% (primer 2). Band B is a single copy fragment, and was found to be an allelic loss in gastric and colon cancers. It is a novel sequence and was registered in GenBank with Accession Number AF151005. Further analysis revealed that it might be part of a cis-regulatory element of a new tumor suppressor gene, containing a promoter of cis-action 'CACA' box, an enhancer of 'GATA' family and a start codon. CONCLUSIONS: It was impossible or difficult to get great achievements for cancer treatments with the procedure of gene therapy only to one oncogene or one tumor suppressor gene because the extensive DNA variations occurred during the progression of tumor. RAPD assay connected with other techniques was a good tool for the detection of genomic instabilities and direct screening of some new molecular markers related to tumor suppressor genes or oncogenes.

EXPONENTIAL STABILITY OF A REPARABLE MULTI-STATE DEVICE

The exponential stability of a multi-state device is discussed in this paper. We present that the Co-semigroup generated by the system operator is quasi-compact and irreducible. It is known that 0 is a simple eigenvalue of the system operator. In combination with this, we obtain that the time-dependent solution exponentially converges to the steady-state solution, which is the positive eigenfuction corresponding to the simple eigenvalue O.

Photonic quantum network transmission assisted by the weak cross-Kerr nonlinearity

Classical network coding permits all internal nodes to encode or decode the incoming messages over proper fields in order to complete a network multicast. Similar quantum encoding scheme cannot be easily followed because of various quantum no-go theorems. In this paper, to avoid these theorems in quantum multiple-source networks, we present a photonic strategy by exploring quantum transferring approaches assisted by the weak cross-Kerr nonlinearity. The internal node may nearly deterministically fuse all incoming photons into a single photon with multiple modes. The fused single photon may be transmitted using twophotonic hyperentanglement as a quantum resource. The quantum splitting as the inverse operation of the quantum fusion allows forwarding quantum states under the quantum no-cloning theorem. Furthermore, quantum addressing schemes are presented to complete the quantum transmissions on multiple-source networks going beyond the classical network broadcasts or quantum n-pair transmissions in terms of their reduced forms.

OPTIMAL SUBSTRUCTURE OF SET-VALUED SOLUTIONS OF NORMAL-FORM GAMES AND COORDINATION

A number of solution concepts of normal-form games have been proposed in the literature on subspaces of action profiles that have Nash type stability. While the literature mainly focuses oil the minimal of such stable subspaces, this paper argues that non-minimal stable subspaces represent well the multi-agent situations to which neither Nash equilibrium nor rationalizability may be applied with satisfaction. As a theoretical support, the authors prove the optimal substructure of stable subspaces regarding the restriction of a game. It is further argued that the optimal substructure characterizes hierarchical diversity of coordination and interim phases in learning.

Modal Decomposition for the Analysis of the Rotor-stator Interactions in Multi-stage Compressors

A modal analysis method of the rotor-stator interactions in multistage compressors has been developed by LMFA. This method, based on a double modal decomposition of the flow over space and time, has been applied to nu- merical and experimental results of the high-speed 3Y2-stage compressor CREATE based at LMFA, Lyon-France. It reveals the presence of a very strong rotor-stator interaction which completely drives the flow at casing behind all the rotors. This modal analysis method applied to an unsteady RANS simulation permits to calculate the en- ergy of the rotor-stator interactions and to plot energetic meridian maps to explain experimental results and to analyze the interaction in the whole machine.

Platinum nanoparticles supported MoS2 nanosheet for simultaneous detection of dopamine and uric acid

Herein, platinum nanoparticles-decorated molybdenum disulfide （PtNPs@MoS2） nanocomposite has been synthesized via a microwave-assisted hydrothermal method, which was characterized by transmission electron microscopy （TEM） and powder X-ray diffraction （XRD）. This MoSz-based nanocomposite modified glass carbon electrode （PtNPs@MoSz/GCE） exhibited excellent electrocatalytic activity toward dopamine （DA） and uric acid （UA） due to their synergistic effect. Two well-defined oxidation peaks of DA and UA were obtained at PtNPs@MoS2/GCE with a large peak separation of 160 mV （DA-UA）, sug- gesting that the modified electrode could individually or simultaneously analyze DA and AA. Under the optimal conditions, the peak currents of DA and UA were linearly dependent on their concentrations in the range of 0.5-150 and 5-1000 gmol/L with detection limit of 0.17 and 0.98 gmol/L, respectively. The proposed MoSz-based sensor can also be employed to examine DA and UA in real samples with satisfactory results. Therefore, the PtNPs@MoS2 nanocomposite might offer a good possibil- ity for electrochemical sensing and other electrocatalytic applications.

Entangler and analyzer for multiphoton Greenberger-Horne-Zeilinger states using weak nonlinearities

In the regime of weak nonlinearity we present two general,feasible schemes for manipulating photon states.One is an entangler for generating any one of the n-photon Greenberger-Horne-Zeilinger(GHZ)states.Interactions of the incoming photons with crossKerr media followed by a phase shift gate and a measurement on a probe beam plus appropriate local operations using classical feed-forward of the measurement results allow one to obtain the desired states in a nearly deterministic manner.The second scheme discussed is an analyzer for multiphoton maximally entangled states,which is derived from the above entangler.In this scheme,all of the 2nn-photon GHZ states can,nearly deterministically,be discriminated.