查询词典 gradient of scalar field

Trichogramma showed high control efficacy on cotton bollworm eggs after three times of release both in the second and in the third generation bollworm periods. The parasitism on the second and third generation bollworm eggs were 66.0%-70.7% and 76.0%-81.2%, respectively, which were significantly higher than that in the control (second generation: 7.0%-12.3%, third generation: 5.2%-7.4%). And the injury rate of cotton buds and bolls in the second and third generation bollworm were 2.2% and 3.1%, respectively, which were significantly lower than that in the control (second generation:8.5%, third generation: 20.9%). In the second generation bollworm period, number of bollworm eggs or larvae in the Trichogramma released cotton field did not differ to that in the chemically controlled field. But in the third generation, there were significantly less bollworm eggs and larvae in the Trichogramma released cotton field. There were more predators in the Trichogramma released cotton field. These results indicated that cotton boll worm in the transgenic insect-resistant cotton field can he effectively controlled by mass-releasing of T.

结果发现：棉铃虫卵在棉株不同部位的分布差异较大，2代棉铃虫卵主要分布在叶正面、叶背面和茎尖，3代棉铃虫卵主要分布于蕾铃；在放蜂田，赤眼蜂对棉株不同部位棉铃虫卵的寄生率差异较大，2，3代棉铃虫时期对叶正面、叫背面、茎尖、蕾铃的棉铃虫卵寄生率均较高，对叶柄和茎杆处卵的寄生率较低；并以3代棉铃虫时期的寄生率较高；在2，3代棉铃虫时期分别连续释放3次赤眼蜂，对棉铃虫具有很强控制作用，2，3代棉铃虫卵的被寄生率分别为66.0%~70.7%和76.0%~81.2%，均显著高于化防田的自然寄生率（2代：7.0%~12.3%，3代：5.2%~7.4%）；蕾铃被害率分别为2.2%和3.1%，均显著低于化防田（2代：8.5%，3代：20.9%；2代棉铃虫时期，放蜂田和化防田的棉铃虫卵量和幼虫数量差异均不显著，但3代棉铃虫以后，放蜂田棉铃虫卵量和幼虫数量均显著低于化防田，且放蜂田的捕食性天敌数量显著高于化防田。

The big event attracts many primary enterprises and their representatives to be present and you may see the following world-famous regular exhibitors: Yuanda in curtain-walling system ; Shide Group ,Nanshan ,Huajian in Profile field ; Siegen-Aubi ,Giesse, Kinlong,Liphing Yeung's and HEHE in Hardware field;YKK AP,Jansen ,Aluk ,Azon in fenestration field ; Wegoma ,Tianchen ,Deca ,Pinghe-huaya in equipment field ;BASF ,Baiyun, zhijiang,Newandon in sealing products field.

在国内外享有盛誉的幕墙领域的沈阳远大公司，玻璃领域旭硝子、中航三鑫集团；型材领域大连实德集团、南山铝业集团、山东华建集团；五金配套件领域德国丝吉利娅、意大利吉斯、坚朗、立兴杨氏、佛山合和；门窗幕墙系统领域YKK AP、瑞士严实、阿鲁克、美国亚松；设备领域德国威格玛、天辰集团、德佳控股公司、平和华亚公司；密封材料领域巴斯夫、广州白云、杭州之江、新安东、成都硅宝等全球知名企业已经悉数报名参展。

In this thesis, we focus on the theory for the interaction of molecular dipole moment with external electric field and use the numerical simulation to investigate the rotational state-selection of polar molecules in a hexapole electric field and the laser-field role of alignment or orientation for molecules based on semi-classical treatment, the detail is the numerical calculation for a quantum mechanical treatment of molecules and their interaction with the external field and a classical electrodynamical treatment for static electric field.

本文研究是在描述分子偶极矩（永久偶极矩或诱导偶极矩）和外电场相互作用的基础上，我们建立了对分子态选择和角动量取向、准直研究的半经典理论框架（即分子体系状态、能量及与外场相互作用使用量子理论描述，分子的运动轨迹使用经典电动力学描述），并利用数值计算方法对静电场和随时间变化电场作用下分子的转动态选择、取向和准直过程进行了研究。

A mathemetical model of magnetic field in electromagnetic separation of inclusions from molten aluminum under rectangle coil and 50Hz current is presented according to the magnetic vector potential integral equation and the basic theory of magnetohydrodynamics. The magnetic field distribution in the gap of coils is simulated by the model and the actual magnetic field distribution also is measured. The experimental results show that the magnetic field distribution in the gap of coils is uniform and is consistemt with the model simulation. The magnetic field designed accord the simulated result is proved suitable in the practice.

摘 要：根据电磁流体力学的基本理论，利用矢量磁位积分，建立了在采用矩形电磁线圈和工频电源的条件下电磁分离铝熔体中夹杂的电磁场数学模型，模拟计算了电磁感应线圈气隙中的磁场分布状态，同时对制做的感应线圈的实际磁场进行了测量模拟计算磁场的分布状态与实际磁场的测量结果基本一致，都表明在电磁感应线圈气隙中磁场分布均匀，可以进行分离铝熔体中的非金属夹杂。

Thirdly, according to the development of the frozen soil, the coupling model of single freezing pipe of axial symmetry of temperature field, stress field and moisture migration is put forward firstly. Then, by means of the progressing principle of potential field, the coupling model of temperature field, stress field and moisture migration which is under the condition of the multi-freezing pipes is extended. At last, the energy balance equation, stress balance equation, quality balance equation, geometric equation, physical equation, initial and boundary conditions etc are adopted to give the analytic solution to the problem of plane axial symmetry of single freezing pipe.

第三，在对室内试验和现场实测结果研究的基础上，分析了土体冻结过程中温度场、应力场、水分场耦合原理，并按照冻土体形成发展过程，首先建立了单一冷源冻结轴对称温度、应力、水分场耦合模型；接着利用势场的迭加原理，将单一冷源情况的三场耦合问题推广到多冷源情况的三场耦合；最后根据能量守恒平衡方程、应力平衡方程、质量守恒平衡方程、几何方程、物理方程、初始及边界条件，解出了单一冷源平面轴对称问题的解析解。

The size of tested field was measured using comparison between the tested field image caught through CCD and the plotting paper image when plotting paper was placed in the tested field position with no plasma jet; the emission intensity distribution of tested field was obtained using stepping motor taking fiber probe to scan tested field, and the spectrum analysis instrument was used to show the spectrum intensity information.

通过CCD获得的待测场图像与没有射流射出时在待测场处放置的坐标纸图像进行比对，测量了实际待测场的大小；利用步进电机带动光纤探针对待测场进行扫描，通过光谱仪获得了待测场的光强分布。

In chapter 1, an up to now synthetically evaluation is given on the research ways and conclusions about jet in cross-flow. Considering the shortage of previous research ways and techniques (the instantaneous flow field and vortices field can not be properly get), in addition to the deficiency of corresponding conclusion (mainly concentrate on the analysis of time-average but little on structures of flow and action of vortex), the research way and content is draft out in this part. Though PIV, the time-average, instantaneous flow field and vortices field can be get, that will unveil the coherent vortex and its course of generation, development and evolvement, with the assistance of K-ε model and Hybrid Finite Analytic Method , which will proof-test the experiment result and bring some complementary, more profound research about the 3-D characters can be done. Using some fundamental topological theory and principle on flow analysis, with anglicizing of vortex structure, a reasonable description is the topological characteristic of near field in JICF given.

首先在第一章中对横流中湍射流的以往研究方法和研究成果给予了综合的评述，针对横流中湍射流旋涡结构以往研究中研究方法的局限性（不能很好得到流动的瞬态流场及涡量场）和相应研究成果中存在的不足（大都集中在时均特性的分析，对流动的内部结构和旋涡的运动阐述很少），明确了本文的研究方法和研究内容：通过PIV流动测量显示技术得到流动的时均及瞬态流场、涡量场，来揭示横流中湍射流的时均、瞬态流场、涡量分布特性，和各种具有拟序结构性质的复杂涡系的产生、发展及演化过程；结合湍流k-ε双方程模型及相应的HFAM计算方法，对于实验进行相互验证和补充，从而更为充分地研究各种旋涡的三维特性；利用拓扑分析的一些基本原理及相关规则，依据对各种旋涡结构的分析，做出对射流近区流场拓扑性质的合理描述。

Motor speed is controlled by varying the current in the field windings.for example,when the amount of current flowing through the field windings is increased, the field strength increases, causing the armature wingdings to produce a larger counter EMF which slows the motor.conversely,when the field current is decreased, the field strength decreases, and the motor speeds up because the conter EMF is reduced.

调速控制的不同目前在外地windings.for例如，当电流流动量的通过外地绕组是增加，电场强度的增加，导致电枢wingdings产生较大的反电势而减慢motor.conversely当外地电流降低，电场强度降低，电机的速度，因为conter电磁场降低。

The results show:(1) that the dynamical properties in the system depend on the degree of entanglement of the initial two identical two-level entangled atoms and the intensity of the coherent optical field, and the atomic dipole moment can be completely squeezed via choosing optimal degree of entanglement of the initial atoms in the feeblish optical field;(2) that the quantum properties of the system also depend on the degree of entanglement of the initial two identical two-level entangled atoms and the intensity of the coherent optical field, and the radiation field can be effectively squeezed via choosing optimal degree of entanglement of the initial atoms in the feeblish optical field.

结果表明：(1)相干态光场的强度和两原子的初始纠缠度对原子的动力学行为有很大的影响。原子布居的振荡频率及幅度和原子偶极压缩的演化规律与光场强弱和两原子初始纠缠度相关联。在弱光场下，选择合适的两原子初始纠缠态，原子偶极矩可以完全被压缩。(2)相干态光场的强度和两原子的初始纠缠度对光场的量子特性也有很大的影响。光场的二阶相干性质和光场的压缩效应均与光场强度和两原子纠缠度相关联。在弱光场中，选择合适的两原子初始纠缠度，光场压缩深度和时间可达到最大。

Based on the analysis of displacement of the electron in transverse magnetic field ,computation of magnetic field of Helmholtz coil and the analysis of uniform scope of magnetic field,the expression of the electron displacement with magnetic field intensity in intensitive uniform magnetic field is modified by the authors.

为了衡量电子在横向磁场下的偏移量的实验中所测数据的优劣性，分析了电子在横向磁场下的偏移原理，，通过亥姆霍兹线圈全空间磁场的计算和磁场均匀性范围的分析；修正了电子在匀强磁场中偏移距离与磁感应强度的关系式，得到了电子在磁场中的偏移距离与产生匀强磁场的电流以及磁场大小的偏差率之间的关系以及成立的条件。

You can snipe the second and third union leaders from this position.

您可以鹬第二和第三工会领袖从这一立场出发。

Aiming at the currently shortage of XML streams quality detecting, this paper proposes a new forecasting method of XML streams quality by least squares support vector machines, which is used the method of XML keys' vector matrix as windows, and vector product wavelet transform to multilevel decompose and refactor the XML streams series, that can fulfill real-time checking demand of XML quality, and ensure constraint, consist- ency and integrality. For even more adapting net load, it proposes a control strategy by weight and adaptive adjustment to ensure XML streams quality.

针对当前XML数据流质量检测存在的不足，提出构建XML键的矢量矩阵作为窗口，利用矢量积小波变换多级分解与重构XML数据流，再结合最小二乘支持向量机对XML数据流质量进行预测的一种方法，满足XML数据流质量重构时实时检测的要求，保证XML数据的约束性、一致性与完整性；为了更好的适应网络负载，采取加权与自适应窗口调整等调度策略充分保证XML数据流的质量检测。