电动车用轮毂电机场路耦合分析

针对电路模拟法和电磁解析法难以准确计及铁磁材料磁导率非线性的影响,以及磁场有限元法难以分析外电路为非标准正弦激励等问题,采用场路耦合法分析电动车用轮毂电机特性,将电磁场有限元方程与外电路方程联立求解,充分考虑外电路中时间谐波电流等非线性因素对磁场的影响,实现电磁场量和电气量的直接耦合。推导轮毂电机电磁场与外电路耦合离散方程、机械运动方程以及功率损耗方程,计算其负载感应电动势和功率损耗,对比分析磁场有限元法和场路耦合法计算结果的差异,并研究轮毂电机功率损耗密度的分布规律。分别采用磁场有限元法和场路耦合法计算在不同工况运行时电机的效率特性,通过样机实验对比分析,结果表明:场路耦合法计算结果更准确,证明所用分析方法的正确性。     

高速开关磁阻电机的电感计算与运行分析

高速开关磁阻电机(SRM)常采用角度控制方式(APC),因而准确计算电感曲线,确定开通关断角对电机的控制非常重要.本文采用能量增量法计算了SRM的静态电感和动态电感特性,分析比较得出动态电感能更好地反映电机的动态特性及饱和特性.根据高速运行的SRM动态电感,确定了合适的角度控制方案.基于有限元软件JMAG-studio,采用场-路耦合方法,对高速SRM运行于APC的工况进行分析计算,得到了电机的磁场分布及电流、转矩特性.     

PWM控制隔爆异步电机定子绕组短路损耗分析

矿用隔爆电机是煤矿井下设备的主要驱动电机,大部分采用逆变器供电,使得电机的谐波损耗增大;定子绕组短路故障是电机的主要故障类型,发生短路故障后,电机的损耗也会发生变化,对PWM供电防爆异步电机定子绕组短路故障损耗变化的研究对电机温度场的研究和故障诊断具有重要的理论意义。为了对定子绕组故障后的电机损耗的特点和变化规律进行研究,建立了一台刮板输送机用防爆异步电动机定子绕组短路故障时的场-控-路耦合二维有限元模型,首先对电机的定子电流和气隙磁密的进行计算,然后对电机的铜耗、磁滞损耗和涡流损耗进行了计算和分析。通过分析可知:电机发生定子绕组短路故障后,故障相的电流增大,使得电机的铜耗大大增加,磁滞损耗和涡流损耗也增加。通过对电机整体损耗的分析,为电机温度场的计算和故障诊断提供理论依据。     

分析感应式电气变速器的电磁耦合与解耦控制技术

针对感应式电气变速器的电磁耦合与解耦控制技术问题,研究了耦合场具有的分布规律以及对主要参数产生的重要影响。利用仿真有限元对电气变速器进行定量计算,并准确把握内外电机的自感与互感出现的变化范围,根据所获得的电感数值同时结合数学系统模型进行建模,研究结果表明计算变参数解耦的准确性。     

新型高速永磁电机的场路耦合分析

通过分析高速永磁电机的特点与关键技术,并在此基础上进行了一台60 000 r/min,100 kW的高速永磁电机的定、转子结构设计,提出了一种新的既有利于降低转子表面电磁损耗又有利于电机通风散热的定子结构和一种可满足高速电机机械和电磁性能要求而且加工和充磁工艺简单的新型永磁转子结构.然后,利用场路耦合分析,计算了高速永磁电机的空、负载特性和电机内的电磁场,部分验证了这种特殊结构的永磁同步电机电磁设计的合理性.     

裂隙岩体介质温度、渗流、变形耦合模型与有限元解析

在建立了岩体裂隙介质三场耦合微分控制方程的基础上,推导了岩石、裂隙,水,气三相介质的温度场、变形场、渗流场耦合模型及有限元解析格式和分析计算方法,对国内某煤矿的多孔裂隙介质三场耦合实际工程问题进行了求解,对结果的可靠性及分析精度进行了论证.     

基于Surrogate方法的低速大扭矩门用电机机壳振动噪声优化

门用电机振动与噪声的研究对改善公共交通领域乘客体验有极大的促进作用.由于应用场景中机械电磁环境较为复杂,基于电磁力波计算的传统永磁电机振动噪声方法存在计算不精确、多物理场耦合优化模型不紧密等问题.本文提出一种基于Surrogate方法的分数槽永磁同步电机八边形机壳设计方案,通过有限元仿真获取先验数据,利用克雷金法重构Surrogate数学模型,经误差修正后,采用搜索算法对电机机壳振动噪声进行优化.结果表明,本文方法对多物理量耦合仿真优化具有较高的拟合精确度与较快的计算速度,具有良好的工程可行性.     

抽水蓄能发电电动机三维瞬态涡流场有限元分析

对广州抽水蓄能B厂某发电电动机进行了三维涡流场有限元计算,建立了发电电动机的三维模型,分析了电流密度、磁密等场量的分布情况,获得了气隙径向磁密并进行了谐波分析。通过发电电动机的三维瞬态涡流场计算,可以更加准确地得到电机电磁场分布情况,运算结果能够为电机的设计、选型、国产化制造提供相应参考,在电机优化设计方面具有一定的参考价值。     

双馈水轮发电机风摩损耗数值研究

根据双馈水轮发电机结构特点和通风特性,以计算流体力学为基础,建立通风道流体场模型,应用有限体积法对电机内流体流动特性进行数值求解,并对电机内风摩损耗进行计算,进而实现了电机内机械损耗的分离计算.通过与实验数据的对比分析,验证了其计算结果的准确性.对电机内风摩损耗的敏感性因素进行了分析.采用有限体积法进行求解,得出电机风摩损耗,结合轴承摩擦损耗经验公式计算得出电机的机械损耗,以此机械损耗与实验数据比较验证了结果的正确性.进而分析了电机转速、通风道内壁面表面粗糙度以及通风槽钢长度和尺寸等因素对电机风摩损耗的影响.     

直线电机瞬态特性的场路耦合分析法

运用磁网络法,进行了单边直线感应电动机的性能分析。提出了此种电机的磁网络模型,由电磁场方程导出了磁网络的参数,从而考虑了直线电机边端效应、绕组不对称分布等结构特点。场路耦合及机电耦合法的运用,使文中提供的分析模型更接近实际情况,适合于动态特性的分析     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the