三峡水轮发电机全定子非线性热–流体耦合网络模型研究

为了计算水轮发电机水冷定子温度场,提出了基于有限元法计算参数的三峡水轮发电机全定子非线性热–流体耦合网络模型。网络模型中热阻参数均采用有限元法计算发电机三维局部温度模型得到,提高了参数计算准确性。模型计及铜的电阻率和水铜交界面对流换热系数随温度的变化而造成耦合网络方程的非线性。该模型可克服解算定子局部模型时某些边界条件无法确定的问题,同时实现了热网络和流体网络的耦合求解,计算值与实际运行数据基本符合,说明了该模型的正确性和有效性。为研究大型发电机全定子温度场提供了一种新方法。

全金属螺杆钻具定子精密电解加工成形阴极设计

为缩短全金属螺杆钻具定子电解加工阴极设计周期同时提高成形精度,提出了一种粒子群优化BP神经网络的精密成形阴极设计方法,建立了全金属螺杆钻具定子电解加工精密成形阴极设计模型,完成了多弧面成形阴极设计。采用自主研制的大型卧式电解加工设备,在选定参数下实现了材料为38CrMoAlA的4 m长金属螺杆钻具定子的稳定加工,轮廓成形精度为±0.03 mm,表面粗糙度达Ra0.848μm。

基于任意时刻电网故障下的双馈风力发电机定子磁链全响应研究

为研究双馈风力发电机(DFIG)定子磁链的全响应与电网故障发生时刻的关系,通过求解DFIG状态方程,得到任意时刻故障下DFIG定子磁链的解析表达式;利用坐标分解方式研究了定子磁链稳态响应与故障时刻的关系;通过分析定子磁链直流分量的大小,研究了定子磁链自由响应与故障时刻的关系。结果表明,定子磁链稳态响应与故障时刻无关,且其大小随故障时刻的变化呈现2倍工频周期的变化规律。最后通过搭建Matlab/Simulink模型仿真验证了推导公式的准确性和理论分析的正确性,为DFIG低电压穿越时转子侧的控制策略提供了一定的理论依据。

PLC与变频器等智能技术在280吨桥式起重机上的应用

本文介绍了PLC与变频器控制在莱钢新动区280吨桥式起重机上的应用,装置调速性能和启、制动效果好,优化线路和节省成本,故障率低,重点分析了系统抗干扰功能措施及问题处理方法。

浅析变频器与PLC控制在桥式起重机上的应用

介绍了变频器与PLC控制在桥式起重机上的应用,装置调速性能和启、制动效果好,优化线路和节省成本,故障率低,重点分析了系统抗干扰功能的措施及问题的处理方法。

Robust Quantum Secure Direct Communication and Deterministic Secure Quantum Communication over Collective Dephasing Noisy Channel

We propose two schemes for quantum secure direct communication (QSDC) and deterministic securequantum communication (DSQC) over collective dephasing noisy channel.In our schemes,four special two-qubit statesare used as the quantum channel.Since these states are unchanged through the collective dephasing noisy channel,the effect of the channel noise can be perfectly overcome.Simultaneously,the security against some usual attacks canbe ensured by utilizing the various checking procedures.Furthermore,these two schemes are feasible with present-daytechnique.

E24 profile slope stability analysis in Haizhou Opencast Coal Mine of Fuxin

The E24 profile slope analyzed belongs to a series of excavated slopes of the Haizhou Opencast Coal Mine. It seems to be divided into Downslope Part and Upslope Part. Its profile comprises two noticeable coal seams, called the 8# and 9# weak layers, considered as the potential failure surfaces. In consideration of the actual configuration as in the perspective of any modification, assessing the stability of this slope with various profile forms under given conditions, and assessing the risk of instability and quantifying the influence of earthworks or other modifications to the stability of this slope, have constituted the primordial objectives carried out. From assumed potential failure surfaces, any specific profiles and specified slip surfaces are defined. A factor of safety (FoS) is computed for each specified slip surface; the smallest FoS found corresponds to the least favorable slip surface. The safety factor values obtained are compared to the suggested safety factor. Limit equilibrium methods of vertical slices implemented in Slope/W, computer program for slope stability analyses, have been adopted to perform the E24 slope stability analysis. The safety factor values computed with 9# weak layer are lower than for 8#; the factors of safety obtained with Sarma's method are the smallest; more, without groundwater (long term) overall values are greater than those determined under groundwater condition (short term). The lowest safety factor value is found for a profile depending on an adopted earthwork sequence. The E24 profile slope stability analysis shows the instability risk for the deepest weak layer, and also shows the short and long term stability of this slope for the envisaged earth movements. However it demonstrates the existence of instability risk for any earthwork firstly affecting the downslope part.

Single Epoch GPS Deformation Signals Extraction and Gross Error Detection Technique Based on Wavelet Transform

Wavelet theory is efficient as an adequate tool for analyzing single epoch GPS deformation signal. Wavelet analysis technique on gross error detection and recovery is advanced. Criteria of wavelet function choosing and Mallat decomposition levels decision are discussed. An effective deformation signal extracting method is proposed, that is wavelet noise reduction technique considering gross error recovery, which combines wavelet multi-resolution gross error detection results. Time position recognizing of gross errors and their repairing performance are realized. In the experiment, compactly supported orthogonal wavelet with short support block is more efficient than the longer one when discerning gross errors, which can obtain more finely analyses. And the shape of discerned gross error of short support wavelet is simpler than that of the longer one. Meanwhile, the time scale is easier to identify.

Improved Quantum ＂ Ping-Pong＂ Protocol Based on Extended Three-Particle GHZ State

In order to transmit secure messages, a quantum secure direct communication protocol based on extended three-particle GHZ state was presented, in which the extended three-particle GHZ state was used to detect eavesdroppers. In the security analysis, the method of the entropy theory is introduced, and three detection strategies are compared quantitatively by using the constraint between the information eavesdroppers can obtain and the interference introduced. If the eavesdroppers intend to obtain all inforrmtion, the detection rate of the original ＂Ping-pong＂ protocol is 50% ; the second protocol used two particles of EPR pair as detection particles is also 50%; while the presented protocol is 58%. At last, the security of the proposed protocol is discussed. The analysis results indicate that the protocol in this paper is more secure than the other two.

Green large-scale production of N/O-dual doping hard carbon derived from bagasse as high-performance anodes for sodium-ion batteries

Sodium-ion batteries are considered as a promising candidate for lithium-ion batteries due to abundant sodium resources and similar intercalation chemistry.Hard carbon derived from biomass with the virtue of abundance and renewability is a cost-effective anode material.Herein,hard carbon is derived from renewable bagasse through a simple two-step method combining mechanical ball milling with carbonization.The hard carbon electrodes exhibit superior electrochemical performance with a high reversible capacity of 315 mA∙h/g.Furthermore,the initial capacity of the full cell,HC//NaMn0.4Ni0.4Ti0.1Mg0.1O2,is 253 mA∙h/g and its capacity retention rate is 77%after 80 cycles,which further verifies its practical application.The simple and low-cost preparation process,as well as excellent electrochemical properties,demonstrates that hard carbon derived from bagasse is a promising anode for sodium-ion batteries.

Federated unscented particle filtering algorithm for SINS/CNS/GPS system

To solve the problem of information fusion in the strapdown inertial navigation system(SINS)/celestial navigation system(CNS)/global positioning system(GPS) integrated navigation system described by the nonlinear/non-Gaussian error models,a new algorithm called the federated unscented particle filtering(FUPF) algorithm was introduced.In this algorithm,the unscented particle filter(UPF) served as the local filter,the federated filter was used to fuse outputs of all local filters,and the global filter result was obtained.Because the algorithm was not confined to the assumption of Gaussian noise,it was of great significance to integrated navigation systems described by the non-Gaussian noise.The proposed algorithm was tested in a vehicle's maneuvering trajectory,which included six flight phases:climbing,level flight,left turning,level flight,right turning and level flight.Simulation results are presented to demonstrate the improved performance of the FUPF over conventional federated unscented Kalman filter(FUKF).For instance,the mean of position-error decreases from(0.640×10-6 rad,0.667×10-6 rad,4.25 m) of FUKF to(0.403×10-6 rad,0.251×10-6 rad,1.36 m) of FUPF.In comparison of the FUKF,the FUPF performs more accurate in the SINS/CNS/GPS system described by the nonlinear/non-Gaussian error models.

Digital Signatures for e-Government - a Long-Term Security Architecture

The framework of digital signature based on qualified certificates and X. 509 architecture is known to have many security risks. Moreover, the fraud prevention mechanism is fragile and does not provide strong guarantees that can be necessary for flow of legal documents. Mediated signatures have been proposed as a mechanism to effectively disable signature cards. In this paper we propose further mechanisms that can be applied on top of mediated RSA, compatible with the standard format, but providing security guarantees even in the case when RSA becomes broken or the keys are compromised. The solution is immune tokleptographic attacks as only deterministic algorithms are used on user＇s side.

GLOBAL ASYMPTOTIC STABLE ERADICATION FOR THE SIV EPIDEMIC MODEL WITH IMPULSIVE VACCINATION AND INFECTION-AGE

We study the application of a pulse vaccination strategy to eradicate the slowly progressing diseases that have infectiousness in latent period. We derive the condition in which eradication solution is a global attractor, this condition depends on pulse vaccination proportion p. We also obtain the condition of the global asymptotic stability of the solution. The condition shows that large enough pulse vaccination proportion and relatively small interpulse time lead to the eradication of the diseases. Moreover the results of the theoretical study might be instructive to the epidemiology of HIV.

High-throughput sequencing-based genome-wide identification of micro RNAs expressed in developing cotton seeds

Micro RNAs(mi RNAs) have been shown to play critical regulatory roles in gene expression in cotton. Although a large number of mi RNAs have been identified in cotton fibers, the functions of mi RNAs in seed development remain unexplored. In this study, a small RNA library was constructed from cotton seeds sampled at 15 days post-anthesis(DPA) and was subjected to high-throughput sequencing. A total of 95 known mi RNAs were detected to be expressed in cotton seeds. The expression pattern of these identified mi RNAs was profiled and 48 known mi RNAs were differentially expressed between cotton seeds and fibers at 15 DPA. In addition, 23 novel mi RNA candidates were identified in 15-DPA seeds. Putative targets for 21 novel and 87 known mi RNAs were successfully predicted and 900 expressed sequence tag(EST) sequences were proposed to be candidate target genes, which are involved in various metabolic and biological processes, suggesting a complex regulatory network in developing cotton seeds. Furthermore, mi RNA-mediated cleavage of three important transcripts in vivo was validated by RLM-5′ RACE. This study is the first to show the regulatory network of mi RNAs that are involved in developing cotton seeds and provides a foundation for future studies on the specific functions of these mi RNAs in seed development.

A pest control model with state-dependent impulses

In this paper, a pest control model with state-dependent impulses is firstly established, which relies on releasing of natural enemies, together with spraying pesticides. By using the successor function of differential equation geometry rules, the existence of order one periodic solution is discussed. According to the Analogue of Poincare＇s Criterion, the orbitally asymptotic stability of the order one periodic solution is obtained. Furthermore, we investigated the global attractor of the system. From a biological point of view, our results indicate that： （1） the pest population can be controlled below some threshold; （2） compared to single measure, it is more efficient to take two measures for reducing the level of the pests.

Analysis of a malaria model with mosquito host choice and bed-net control

A malaria model is formulated which includes the enhanced attractiveness of infectious humans to mosquitoes, as result of host manipulation by malaria parasite, and the human behavior, represented by insecticidetreated bed-nets usage. The occurrence of a backward bifurcation at R0 = 1 is shown to be possible, which implies that multiple endemic equilibria co-exist with a stable disease-free equilibrium when the basic repro- duction number is less than unity. This phenomenon is found to be caused by disease- induced human mortality. The global asymptotic stability of the endemic equilibrium for R0 〉1 is proved, by using the geometric method for global stability. Therefore, the disease becomes endemic for R0〉 1 regardless of the number of initial cases in both the human and vector populations. Finally, the impact on system dynamics of vector＇s host preferences and bed-net usage behavior is investigated.