电容器单元爆破能量与电容器组接线结构方式之关系

在工程项目中,经常有用户提出电容器单元的耐爆能量要求,因此,认真分析爆破能量与电容器组及其结构的关系十分重要。文章就针对这个问题进行了探讨。

小型断路器接线端子温升研究

小型断路器接线端子温升是产品开发设计中的主要性能,也是火灾防患的重要参数,对产品的实际使用有重要的影响。其中电流大小、导线类型和规格、接线框的结构设计、拧紧力矩等都是影响接线端子温升的重要因素。主要通过试验对比不同影响因素下的端子温升,获得一些重要结论。

基于多媒体软件的数码插画应用研究

针对原有数码插画应用在空间制图方面存在顶点分布不均、连接线结构散乱等问题,提出并设计了基于多媒体软件的数码插画应用系统。通过功能设计、技术框架设计,搭建多媒体数码插画应用软件环境,通过四元素转换、插值转化,完成数码插画硬件的设计。实验结果表明,改进的基于多媒体软件的数码插画应用系统既能保证空间制图各顶点有序分布,也能解决连接线结构散乱的问题,具有一定优势。

矿井低压真空馈电开关智能综合保护器的硬件设计

介绍了一种基于数字信号控制器的矿井低压真空馈电开关智能综合保护器的硬件设计,阐述了在该智能综合保护器硬件设计过程中的技术创新点,包括选用dsPIC30F6014A数字信号控制器、设计了负电压产生电路和备用电源、增加了液晶背光控制电路、增加了瓦斯频率输入部分。该智能综合保护器采用4层电路板结构以减小尺寸和提高抗干扰能力,并采用外部接线端子排接线结构,便于在井下更换。测试结果验证了该智能综合保护器的可行性。

电动汽车充换电设施接入电网典型模式研究

本文结合当前电动汽车及充换电设施的发展现状,分析了充换电设施接入配电网带来的影响,充换电设施接入配电网的技术要求,提出了电动汽车充换电设施接入电网的典型模式。

A Position-Based Handoff Scheme in WAVE Systems

IEEE 802.11p has been proposed to extend the application of IEEE 802.11 to Wireless Access fast fading Vehicular Environments (WAVE).Due to the high velocities of vehicles and thus the inconstant topology of networks,it is extremely difficult to maintain communications without handoff in an Internet of Vehicles (IoV).Hence,fast handoff from one roadside unit (RSU) to another is necessary.Although some solutions have been given in IEEE 802.11r and 802.11f standards,the handoff latency is still as high as about 50 ms when adopting them.To address this issue in WAVE systems,a novel position-based handoff (PHO) scheme is proposed in this paper.In PHO scheme,the triggering of the handoff is accomplished by the location information of a vehicle instead of the power level of the received signal.Both the handoff process and latency of PHO scheme are analyzed.Finally,to verify the analytical results,simulations were conducted to date the effectiveness of the proposed PHO scheme.

Fatigue Strength Evaluation of Resin-Injected Bolted Connections Using Statistical Analysis

Different strategies can be used to perform reparations and reinforcements of ancient bolted and riveted metallic bridges. As the riveting process is not currently a common practice, it requires proper equipment and skilled workers. Another solution is the use of welding. However, the weldability of old steels is poor. Bolts are very attractive alternative solutions, and are most commonly used to repair old metallic bridges. Fitted bolts are expensive solutions; the alternative is the use of resin-injected bolts. The behavior of bolted joints with preloaded resin-injected bolts has been studied using quasi-static and creep tests; however, few studies on the slip and fatigue behavior of these joints can be found in the literature. This paper presents an overview of a few experimental programs that were carried out by several authors aiming at evaluating the fatigue behavior of single and double shear resin-injected bolted connections. A comparison between the experimental data of joints with preloaded standard bolts and preloaded resin- injected bolts shows a fatigue strength reduction in the latter. Since Eurocode 3 （EC3） suggests the same fatigue strength curve for joints made of resin-injected bolts and standard bolts, this may raise some con- cerns. Furthermore, research on the feasibility of using both bonded and bolted connections is shown. This last study was performed with high-strength low-alloy structural steel plates and an acrylic struc- tural adhesive for metal bonding. For both case studies, a statistical analysis is performed on fatigue experimental data using linearized boundaries and the Castillo and Fernandez-Canteli model. Fatigue design curves are proposed and compared with the design suggestions of several European and North American standards,

Nonlinear identification and characterization of structural joints based on vibration transmissibility

In order to investigate the nonlinear characteristics of structural joint,the experimental setup with a jointed mass system is established for dynamic characterization analysis and vibration prediction,and a corresponding nonlinearity identification method is studied.First,the sine-sweep vibration test with different baseexcitation levels areapplied to the structural joint system to study the dominant modal of mass rigid motion.Then,based on t e harmonic balance method principle,t e measured vibration transmissibilities a e utilized for nonlinearity identification using different excitation levels.Experimental results show that nonlinear spring and damping force can be represented by a polynomial order approximation.The identified nonlinear stiffness and damping force can predict the system’s response,and they can reveal t e shifts of resonant frequency or damping due to discontinuity of contact mechanisms within a certain range.

箱式变压器在煤矿供电系统改造中的应用

针对现有系统变压器缺少保护控制装置,以及供电可靠性差的问题,对其设计采用箱式变压器的技术改造,既提高供电质量,又具备一定的补偿作用。经实际运行,取得了良好的效果。

Longitudinal forces of continuously welded track on high-speed railway cable-stayed bridge considering impact of adjacent bridges

A proven beam-track contact model was used to analyze the track-structure interaction of CWR (continuously welded track) on bridge. Considering the impact of adjacent bridges, the tower-cable-track-beam-pier-pile finite element model of the cable-stayed bridge was established. Taking a bridge group including 40-32m simply-supported beam and (32+80+112)m single-tower cable-stayed bridge and 17-32m simply-supported beam on the Kunming-Shanghai high-speed railway as an example, the characteristics of CWR longitudinal force on the cable-stayed bridge were studied. It is shown that adjacent bridges must be considered in the calculation of the track expansion force and bending force on cable-stayed bridge. When the span amount of adjacent bridges is too numerous, it can be simplified as six spans; the fixed bearing of adjacent simply-supported beams should be placed on the side near the cable-stayed bridge; the track expansion device should be set at the bridge tower to reduce the track force near the bridge abutment.

Novel Localized Excitations of Nonlinear Coupled Scalar Fields

Some extended solution mapping relations of the nonlinear coupled scalar field and the well-known φ^4 model are presented. Simultaneously, inspired by the new solutions of the famous φ^4 model recently proposed by Jia, Huang and Lou, five kinds of new localized excitations of the nonlinear coupled scaiar field （NCSF） system are obtained.

One-Branch Zero-IF Wireless Receiver Topology with Multiphase Local Oscillator

This paper proposes a one-branch zero-IF receiver topology, which samples the I and Q signals of the modulated RF carrier with one signal path by means of a multiphase local oscillator. The suggested one-branch re- ceiver works without matching problem, and it is also capable of cancelling out the flicker noise and DC-offset when the local oscillator is configured to the four-phase mode. The one-branch receiver saves much area and power com- pared with the traditional two-branch ones. All of the advantages above make the one-branch receiver topology a promising architectural candidate for low-power and low-cost RF CMOS receiver designs. Keywords： RF CMOS; zero-IF; flicker noise; image rejection; low-power; IQ matching

Analysis and Modeling of k-regular and k-connected Protection Structure in Ultra-High Capacity Optical Networks

This paper proposes k-regular and k-connected(k&k) structure against multifaults in ultra-high capacity optical networks.Theoretical results show that pre-configured k&k structure can reach the lower bound on logical redundancy.The switching time of k&k protection structure is as quickly as ringbased protection in SDH network.It is the optimal protection structure in ultra-high capacity optical networks against multi-faults.We develop the linear programming model for k&k structure and propose a construction method for k&k structure design.Simulations are conducted for spare spectrum resources effi ciency of the pre-confi gured k&k structure under multi-faults on representative COST239 and NSFnet topologies.Numerical results show that the spare spectrum resources efficiency of k&k structure can reach the lower bound on logical redundancy in static networks.And it can largely improve spare spectrum resources effi ciency compared with p-cycles based protection structure without reducing protection effi ciency under dynamic traffi cs.

Clustering Approaches for Overhead Reduction over Coordinated Multiple Points Network-MIMO Downlink Systems

Owing to the potential for intercell cochannel interference mitigation and significant spectral efficiency improvement, coordinating transmission techniques by multiple radio access points have recently attracted a lot of attention. In this paper, the system structure and mathematical signal model based on clustered structure are presented for multipoint coordinating downlink transmission, the clustered supercell configurations with static/dynamic approaches are discussed, and then optimal precod- ing design is provided for an accepted level of scheduling complexity and reduced signaling over- head. Some simulation results are given to evaluate the performance of different cell-clustering approaches, and to show that a clustered supercell size of 7 is a reasonable choice for clustered coordination with the given transmit power and the reduced feedback.

可视对讲系统剖析及选用指南

一个完整的可视对讲系统，大多是由以下几部分设备组成整个结构。

Effect of triple-phase contact line on contact angle hysteresis

Recent studies have shown that the triple-phase contact line has critical effect on the contact angle hysteresis of surfaces.In this study,patterned surfaces with various surface structures of different area fractions were prepared by electron etching on a silicon wafer.The advancing angle,receding angle and hysteresis angle of these surfaces were measured.Our experimental results showed that while the geometry of microstructure and contact line have a minor effect on the advancing angle,they have a significant effect on the receding angle and thus the hysteresis angle.We have shown that the effect of microstructure and the contact line can be described by a quantitative parameter termed the triple-phase line ratio.The theoretical predictions were in good agreement with our experimental results.

Crustal structure of northeastern margin of the Tibetan Plateau by receiver function inversion

Using seismic data of about one year recorded by 18 broadband stations of ASCENT project, we obtained 2547 receiver func- tions in the northeastern Tibetan Plateau. The Moho depths under 14 stations were calculated by applying the H-x domain search algorithm. The Moho depths under the stations with lower signal-noise ratio （SNR） were estimated by the time delay of the PS conversion. Results show that the Moho depth varies in a range of -40--60 kin. The Moho near the Haiyuan fault is vague, and its depth is larger than those on its two sides. In the Qinling-Qilian Block, the Moho becomes shallower gradually from west to east. To the east of 105~E, the average depth of the Moho is 45 km, whereas the west is 50 km or even deeper. Combining our results with surface wave research, we suggest a boundary between the Qinling and the Qilian Mountains at around 105~E. S wave velocities beneath 15 stations have been obtained through a linear inversion by using Crust2.0 as an ini- tial model, and the crustal thickness that was derived by H-x domain search algorithm was also taken into account. The results are very similar to the results of previous active source studies. The resulting figure indicates that low velocity layers devel- oped in the middle and lower crust beneath the transition zone of the Tibet Block and western Qinling, which may be related to regional faults and deep earth dynamics. The velocity of the middle and lower crust increases from the Songpan Block to the northeastern margin of Tibetan Plateau. Based on the velocity of the crust, the distribution of the low velocity zone and the composition of the curst （Poisson＇s ratio）, we infer that the crust thickening results from the crust shortening along the direc- tion of compression.

Geometry of the Second-Order Tangent Bundles of Riemannian Manifolds

Let （M, g） be an n-dimensional Riemannian manifold and T2M be its second- order tangent bundle equipped with a lift metric g. In this paper, first, the authors con- struct some Riemannian almost product structures on （T2M, g） and present some results concerning these structures. Then, they investigate the curvature properties of （T2M, g）. Finally, they study the properties of two metric connections with nonvanishing torsion on （T2M, g： The//-lift of the Levi-Civita connection of g to TaM, and the product conjugate connection defined by the Levi-Civita connection of g and an almost product structure.

An unexpected tetranuclear Li_2Cr_2 trimethylsilylacetylide complex bridged by two μ_3-pyrazolates

A tetranuclear Li2Cr2 acetylide precursor complex, [Li(Tp)crm(c=CSiMe3)2(/,t3-pz)]2· (n-pentane)2 (Tp = hydridotris(pyra- zolyl)borate, pz = pyrazolate) (1) has been synthesized and characterized. The X-ray structure analysis shows that the complex contains a Li2Cr2 core bridged by two ,u3-pyrazolates. The magnetic data exhibit the existence of weak antiferromagnetic in- teraction in the cluster.

Synthesis,structure and bonding of the hypoelectronic cluster compound Sr_3Tl_5

The Sr3Tl5 phase was prepared by high temperature synthesis techniques through reaction of the high purity elements in the welded Nb tubes.The structure established through X-ray structural analysis shows the compound is a good hypoelectronic trielide example of the Pu3Pd5 structural type in which skeletal electron count is lower than in a traditional Zintl phase(Cmcm,Z = 4;a = 10.604(2) ,b = 8.675(2) ,and c = 10.985(2) ;V = 1010.5(3) 3).The strontium size and the compound's polarity appear responsible for this thallium phase crystallization in the Pu3Pd5 family type rather than the isoelectronic Sr3In5 version.A first-principle electronic structure calculation(LMTO) demonstrates that the strontium atoms participate substantially in Sr-Tl bonding in the structure.