Multi-quadric Equations Interpolation and Its Applications to the Establishment of Crustal Movement Speed Field

In this paper,multi_quadric equations interpolation is used to establish a widely covered and valuable speed field model,with which the crustal movement image is obtained.

Suppressing of humping bead using an external magnetic field in high-speed gas metal arc welding

During high-speed gas metal arc welding （GMAW）, the backward flowing molten jet with high momentum in the weld pool is considered to be responsible for the occurrence of humping bead. To suppress humping bead, an electromagnetic device is developed and coupled with the welding system. By adjusting the conditions of external magnetic field, forward electromagnetic force is obtained to reduce the momentum of the backward flow of molten metal in weld pool. Consequently, the humping bead can be suppressed by adjusting the external magnetic field. Bead-on-plate welding experiment was conducted on mild steel plates, and the influence of magnetic flux density on the arc deflection angle and weld bead quality is investigated. It is found that external magnetic field can remarkably adjust the momentum of backward flow jet and significantly improve the quality of weld bead.

Translation speed measurements of hydrogen, helium, and argon field-reversed configurations in the central cell of a KMAX mirror device

A series of experimental results of field-reversed configurations(FRCs) on a KMAX(Keda Mirror with AXisymmetricity) tandem mirror machine are reported.Single-side FRC translation processes with three different gas species were measured by avalanche photodiodes.Consistent with the theoretical prediction, the measured FRC speeds were inversely proportional to the square root of the ion mass.However, the speeds of the hydrogen FRC increased even in a uniform magnetic field region while the speeds of the helium and argon FRCs decreased.Possible mechanisms are discussed.The speed of the second pass due to the reflection of the mirror fields was found to be ~1/3 of the first pass speed.The internal magnetic fields were measured for a colliding-merging argon FRC, and the results show that, even for very slowmoving FRCs, merging can occur.

Pressure Distribution Characters of Flow Field around High-Speed Train

Based on incompressible viscous fluid Navier-stokes equation and k-ε 2-equations turbulent model, an investigation on 3D turbulent flow field around four kinds of train models has been made by finite element method. From the calculation, the pressure distribution characters of now field around high-speed trains have been obtained. It is significant for strength design of the high-speed train body, for resisting wind design of the facilities beside the high-speed railways and for determining the aerodynamic force of induced air to the human body near the railways.

电动叶菜收获机速度协同控制系统设计与试验

针对电动叶菜收获机切割、输送和行走三者速度不协调导致的叶菜损伤率高、功耗大和收获效率低等问题,开发了一种电动叶菜收获机速度协同控制系统。系统以可编程逻辑控制器为核心,利用信息传感模块对割刀电机的电流、电压和转速进行数据采集;主控模块根据速度协同控制算法对采集信号进行处理,得到负载信息并协同切割、输送和行走三者速度。田间试验结果表明:系统稳定可靠,能够根据收获情况动态协同各部件速度参数,叶菜损伤率为8.88%;与传统定速控制方法相比,收获机功耗降低了13.1%,收获效率提升了33.4%。

Mathematical Modeling,Field Calibration and Numerical Simulation of Low-Speed Mixed Traffic Flow in Cities

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Development and application of coupling model of aluminum thin-gauge high-speed casting

Based on the analyses of aluminum melt flow, solidification, heat transfer during the process of twin-roll casting, a coupling mathematical model of aluminum thin-gauge high-speed casting was developed, which included the casting roller shell. At the same time, Galerkin method was adopted to solve the coupling model. The fluid field and temperature field of aluminum melt in casting zone, the temperature field and thermal stress field of roller shells were simulated by the coupling model. When the casting velocity is 7m/min, and the thickness of strip is 2mm, the circumfluent area comes into being in the casting zone, and the mushy zone dominates the casting zone, while the temperature of melt decreases rapidly as it approaches the rollers. The temperature of the roller shell varies periodically with the rotation of roller, and reaches the highest temperature in the casting zone, while the temperature of roller shell decreases gradually as it leaves the casting zone. The difference of thermal stress between the inner surface and outer surface of the roller shell is very large, and the outer surface suffers tensile-compressive stress.

Prediction of high-speed train induced ground vibration based on train-track-ground system model

The development of analysis on train-induced ground vibration is briefly summarized. A train-track- ground integrated dynamic model is introduced in the paper to predict the ground vibration induced by high-speed trains. Representative dynamic responses of the train-track-ground system predicted by the model are presented. Some major results measured from two field tests on the ground vibration induced by two high-speed trains are reported. Numerical prediction with the proposed train-track-ground model is validated by the high-speed train running experiments. Research results show that the wheel/rail dynamic interaction caused by track irregularities has a significant influence on the ground acceleration and little influence on the ground displacement. The main frequencies of the ground vibration induced by high-speed trains are usually below 80 Hz. Compared with the ballasted track, the ballastless track structure can produce much larger train-induced ground vibration at frequencies above 40 Hz. The vertical ground vibration is much larger than the lateral and longitudinal components.

The Influence of Longitudinal Magnetic Field on the CO_2 Arc Shape

The COarc welding was carried out under a longitudinal magnetic field,and the arc shape has been studied by using a high-speed camera.From the camera images,we know that under the action of the longitudinal magnetic field,the upper end of the arc will constrict and the lower end of the arc will expand.It would become a bell-type shape and rotate at a highspeed in the optimum range of magnetic field parameters.The arc shape was simulated using a mathematical model,which was established based on experiment data and theoretical knowledge,and mechanism analysis has been carried out regarding the effect of longitudinal magnetic field on COwelding arcs.

Effects of electrode configuration on electroslag remelting process of M2 high-speed steel ingot

The electrode configuration determines the thermophysical field during the electroslag remelting(ESR) process and affects the final microstructure of the ingot. In this work, ingot with a diameter of 400 mm was prepared with two electrode configuration modes of single power ESR process, namely one electrode(OE) and two series-connected electrodes(TSCE). Finite element simulation was employed to calculate the electromagnetic field, flow field and temperature field of the ESR system. The results show that the temperature of the slag pool and the metal pool of the TSCE process is lower and more uniform than that of the OE process.The calculated temperature distribution of the ingot could be indirectly verified from the shape of the metal pool by the experiment. The experimental results show that the depth of the metal pool in the OE ingot is about 160 mm, while the depth of the TSCE ingot is nearly 40 mm shallower than that of the OE ingot. Microstructural comparisons indicate that coarse eutectic carbides are formed in the center of the OE ingot, whereas more even eutectic carbides appear in the center of the TSCE ingot. In general, compared with the OE process, the TSCE process is preferred to remelt high speed steel ingots.

Effect of flow field distribution on the synthesis of sub-micron ZSM-5 molecular sieve in a quasi-solid system

Scale-up synthesis of sub-micron ZSM-5 molecular sieve in a quasi-solid system was investigated. Compared with traditional hydrothermal synthesis, the synthesis in a quasi-solid system has the advantages of high yield, short crystallization time, low energy consumption as well as low emissions. However, the high solid content in the quasi-solid system can cause the mass and heat transfer problems and make scalable production difficult. In order to solve the problem, we have developed a method for the optimization of the mass and heat transfer. By this method one can vary the flow field in the reactor by changing the stirrer speed. Scale-up synthesis of the sub-micron ZSM-5 molecular sieve in a quasi-solid system was carried out in a 5 L reactor with double propeller-type agitators. The process was investigated with product characterization using X-ray diffraction （XRD） and scanning electron microscopy （SEM） and the flow field information was collected using laser Doppler velocimetry （LDV）. The results showed that the flow field patterns can be tuned by using different stirrer speeds, the morphology and size of assynthesized of ZSM-5 can be effectively controlled.

核电半速汽轮发电机励磁绕组匝间短路时转子涡流损耗研究

为研究核电半速汽轮发电机励磁绕组匝间短路时转子涡流损耗特性,推导了核电半速汽轮发电机空载运行时励磁绕组匝间短路故障下,定子分数次谐波环流产生的合成磁动势表达式,分析合成磁动势相对于转子的转速,揭示了转子表面产生涡流的原因以及涡流的频率特性。结合涡流损耗计算方法,以一台核电半速汽轮发电机为例进行了仿真验证。在此基础上,对核电半速汽轮发电机励磁绕组不同位置发生相同程度匝间短路,以及励磁绕组发生不同程度匝间短路过程进行了仿真,计算了转子各阻尼条及槽楔中的涡流及涡流损耗,揭示了励磁绕组匝间短路时影响转子阻尼条及槽楔中涡流和涡流损耗的因素。为核电半速汽轮发电机励磁绕组匝间短路故障时,分析转子发热的影响因素提供了理论基础。

Influence of longitudinal magnetic field on metal transfer in MIG arc welding

Metal transfer is an important phenomenon in metal inert gas （MIG） arc welding with longitudinal alternating magnetic field. It is of great significance to observe the metal transfer modes under different excitatory currents and frequencies. However, it is very difficult to view the metal transfer process directly during welding, due to the strong interference from the arc light. To obtain the relationship between the metal transfer modes and the different magnetic fields, a high-speed video camera was used to acquire the images of globules. Different metal transfer modes under the conditions of different magnetic fields and welding parameters were studied. The experiment shows clear images of droplet transfer as well as influence of longitudinal magnetic field on both metal transfer and globule shape.

Contribution to the Investigation of Motorcyclists’ Speed Prediction Equations for Two-Lane Rural Roads

The calculation of speed prediction equations has been the subject of numerous researches in the past. The majority of them present models to predict free-flow speed in terms of the road geometry at the curved road sections and more specifically in terms of the radiuses of the curves. Common characteristic is that none of them approaches the speed behavior of motorcycles since they are excluded from the datasets of the various studies. Instead, the models usually predict operating speed for other vehicle types such as passenger cars, vans, pickups and trucks. The present paper aims to cover this gap by developing speed prediction equations for motorcycles. For this purpose a new methodology is proposed while field measurements were carried out in order to obtain an adequate dataset of free-flow speeds along the curved sections of three different two lane rural roads. The aforementioned field measurements were conducted by two participants incorporating various road conditions (e.g. light conditions, experience level, familiarity with the routes). The ultimate target was the development of speed prediction equations by calculating the optimum regression curves between the curve radius’ and the corresponding velocities for the different road conditions. The research revealed that the proposed methodology could be used as a very useful tool to investigate motorcyclists’ behavior at curved road sections. Moreover it was feasible to draw conclusions correlating the speed adjustment with the various driving conditions.

Numerical analysis of external magnetic field for mitigating backward flow momentum in weld pool

The external magnetic field is applied to mitigating backward flow jet of molten metal in weld pool so that humping bead may be suppressed during high speed gas metal arc welding（GMAW）. Therefore, the external magnetic field distribution in workpiece is critical to understand the interaction mechanisms of the external magnetic field with molten metal flow. In this study, the steady state external magnetic field induced by excitation device is numerically analyzed by using the the finite element software ANSYS and the three dimensional static magnetic scalar method. The distribution of external transverse magnetic field By in workpiece and arc area is calculated, and the influence of excitation current and air-gap distance on the distribution of transverse magnetic field By has been discussed. The magnetic field distribution in workpiece is measured by using a Tesla-Meter and compared with the simulated result. It is found that both are in good agreement.

Research on Multi-System Ultra-High Speed Optical Signal Access System

In view of the small transmission capacity and single signal modulation format of the existing optical transmission system, this paper proposes an ultra-high-speed optical signal access scheme based on NEL0670, which can realize the transmission of 100 G DP-QPSK, 200 G DP-16QAM and 400 G DP-16QAM signals, and realize flexible and intelligent reception of multi-system optical signals.

Phantom and Quintessence Fields Coupled to Scalar Curvature in General <i>f(R)</i>Gravity Theory

This paper reviews the development of f(R) gravity theory and Phantom and Quintessence fields. Specifically, we present a new general action of f(R) gravity and Phantom and Quintessence fields coupled to scalar curvature. Then, we deduce Euler-Lagrange Equations of different fields, matter tensor and effective matter tensor. Additionally, this paper obtains the general pressure, density and speed sound of the new general field action, and investigates different cosmological evolutions with inflation. Further, this paper investigates a general f(R) gravity theory with a general matter action and obtains the different field equations, general matter tensor and effective matter tensor. Besides, this paper obtains the effective Strong Energy Condition (SEC) and effective Null Energy Condition (NEC). Then, we prove that when f(R) approaches to R, the effective SEC and the effective NEC approach to the usual SEC and the usual NEC, respectively. Finally, this paper presents a general action of f(R) gravity, Quintessence and Phantom fields and their applications.

考虑台风时空变异性的15 MW海上风电机组来流风速场研究

已有针对大型海上风电机组的抗台风安全研究较少考虑对同一机组台风过境全过程的影响和同一时刻海上风电场不同机组的影响。然而,实际上台风具有显著的时空变异特征,随着海上风电机组日益朝着高大化趋势发展,有必要重新审视台风时空变异性对大型海上风电机组结构安全性的影响。以未来主流大型海上风电机组(15 MW海上风电机组)和主流海上风电场规模为研究对象,基于气象实测数据和台风多阶段风速场数据驱动模型获取了台风“威马逊”(1409)的台风致风速场时空变异特征,并反演了台风“威马逊”影响下同一时刻不同机组和同一机组不同时刻的15 MW海上风电机组的来流风速场,并开展了相应的极值对比分析。研究结果表明,台风时空变异性对海上风电机组的来流风速场影响显著,将导致同一风电场内的不同机组来流风速可能存在量级差异,也意味着相同设计标准下的风电机组在同一台风影响下会存在截然不同的结构安全表现。通过对台风时空变异特征及其引起的来流风速场进行研究,阐明了这些因素对大型海上风电机组结构抗台风安全性影响的重要性,可为面向我国海域的大型海上风电机组安全设计提供参考依据。

电动汽车用新型模块化聚磁转子永磁电机设计及其对比分析

将轮辐型内置式转子和Halbach永磁阵列结合,并取消转子铁心加强筋,减小漏磁达到高聚磁同时兼顾凸极比,实现高转矩/功率密度和宽调速范围。在保证永磁体用量相同的情况下,建立新型高凸极比聚磁转子和V型转子两种电机模型,针对两者的分段转子拓扑,开展电磁性能对比分析,包括气隙磁密、凸极比、功率以及弱磁扩速能力等。同时,考虑到无转子铁心加强筋会导致转子分段存在结构强度问题,仿真验证新型高凸极比聚磁转子结构在最高转速6000 r/min时给予碳纤维护套保护下转子结构强度的可靠性;分析温度限制下新型高凸极比转子电机的功率输出。另外,对比两种不同电机结构的振动噪声情况。最后,研制一台16极/72槽新型高凸极比转子永磁电机样机,实验验证有限元分析结果的准确性。进一步说明了新型高凸极比转子永磁电机在转矩/功率密度和宽调速运行等方面的性能优势。

送风方式对高速列车通风和呼吸污染物扩散特性的影响

高速列车交通网络发达且载客量大,但车厢环境封闭易造成污染物的堆积,为提高乘车舒适性和安全性,基于计算流体动力学理论(CFD),建立满载工况的全尺寸车厢通风计算模型.针对排风口位于两侧车窗上端的排风方式,采用速度不均匀系数、温度不均匀系数、能量利用系数和通风效率作为列车通风系统的评价指标,对比研究6种送风方式对车厢内流场特性和呼吸污染物扩散特性的影响,包括多孔顶板送风、下部送风、多孔顶板送风+下部送风、局部多孔顶板送风、侧顶送风、局部多孔顶板送风+侧顶送风.研究结果表明:通过调整风口之间的流量分配比例可以使送风气流均匀地流向客室两侧,改善车内温度均匀性;采用下部送风时,有助于提高通风系统的能量利用系数和通风效率,分别高达1.38和1.21,但会恶化车内乘坐舒适性;通过研究乘客之间呼吸污染物的相互影响情况发现,第C列乘客的呼吸污染物容易向第B列乘客的呼吸区域进行扩散,加剧乘客之间的交叉感染;通过减小多孔顶板的送风口尺寸,采用局部多孔顶板送风可以有效缓解该现象,使污染物的体积浓度下降至0.0019.