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Based on varying process of generator terminal parameters after excitation fault, shortages of excitation protective principle of static stability boundary and asynchronous impedance boundary are analyzed. It proposed that excitation fault research relates to large-disturbance stability. Because dynamic power-angle character of generator after excitation fault is non-sinusoidal, there are differences between dynamic power-angle character and static state power-angle character. So it isn't ideal to protective operation result based on small-disturbance stability and static stability boundary criterion. At the same time, it proposed that asynchronous boundary impedance criterion is a constant reactive power circle moving adown j Xd′. It can ensure complete loss-of-excitation generator measuring impedance enter into the circle, but can't ensure the other condition measuring impedance including impossible losing synchronism enter. So loss-of-excitation protection would be maloperation when system voltage drops short and recovers or generator rejects load.③Based on stability principle, it puts forward setting conditions and calculation method of generator loss-of-excitation protection by direct measuring power-angle.
以励磁故障后发电机端的相关参数的变化为基础,通过对以静稳定边界和异步阻抗边界作判据的两类三种现行励磁保护在原理上存在的缺陷分析,发现:励磁故障是一个大干扰稳定性问题,励磁故障后的发电机的动态功角特性与静态功角特性有很大的差异,已远非正弦曲线,因此基于小干扰稳定性原理、以静稳定边界作判据的保护必然动作不理想;异步边界阻抗判据是一个下移j Xd′的等无功阻抗圆,它可以保证完全失磁后的发电机测量阻抗能进入该阻抗圆,但不能保证完全失磁之外的其它状态不会进入该阻抗圆,因此在系统电压短时下降或发电机突然甩负荷等情况下可能启动该保护使之误动。
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New type of water chemistry for utility drum boiler and its principle and characteristic Two kinds of water chemistry's main principle and characteristic are detailedly analyzed. Against the problem of high eroding speed, high Fe content in feed water and boiler water, high scaling speed, short chemical cleaning interval, needing poisonous chemical deoxidant, etc for drum boiler's deoxidization water chemistry and difficulty of using oxidation water chemistry, a new type of water chemistry is put forward on the basis of analyzing the characteristic of whole power station's water steam cycle system, principle of two kinds of water chemistry and their practical effect in every cycle stage. Considering two water chemistry's merit, a new water chemistry called Limited Oxidation Water Chemistry is put forward, which is a local slight oxidization no-deoxidant water chemistry. And the proposed method's principle, control parameter, applying condition, start-lay up and emergency measures are initially calculated and analyzed.
三、新型汽包炉水化学工况的提出及其原理和特点详细分析了国内外现行两大类水化学工况处理的核心原理和特点,针对现行汽包炉还原性水化学工况处理所存在的系统腐蚀速度相对较大、给水和炉水铁浓度高、锅炉结垢速度快、机组酸洗间隔短、无法避免有毒化学除氧剂的使用以及氧化性水化学工况在汽包炉机组上应用的困难等问题,在详细分析电站整个水蒸汽循环系统的特点、两类水工况处理的原理和对循环中各段处理的实际效果等的基础上,综合两者的优点,提出了一种新型的局部轻微氧化性无除氧剂汽包炉水化学工况-"汽包炉有限氧化性水化学工况"处理原理,并初步计算、分析和确定了该种新型水化学工况的主要工艺控制参数、应用条件、启停与紧急情况处理等。
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On the basis of dual porosity theory,the well test interpretation model which considers the variation of krg versus the volume of liquid is also established and resolved by the implicit method numerically.
摘要通过分析凝析气藏的相图,建立了凝析液饱和度随压力降的变化规律,并回归得出了相应的公式;同时通过对气体压缩因子、黏度随压力、温度的变化,建立了这些参数和无因次压力的关系;在双重介质地层假设的基础上,建立了在试井过程中凝析气相对渗透率随凝析液饱和度变化的凝析气藏试井解释数学模型,采用隐式迭代的方法进行了求解并进行了参数敏感性分析;结果表明:凝析液的饱和度对凝析气藏试井的压力及压力导数曲线有着很大的影响,早期由于凝析液的析出,阻碍了气藏的流动,导致压力及压力导数曲线上升;在凝析液饱和度达到峰值之后,随着凝析液的挥发,凝析气的相对渗透率逐渐恢复,压力及压力导数曲线又回归到正常的径向流位置;由于裂缝和基岩之间的压力差,使得裂缝弹性储容比在测试过程中发生变化,进而影响了压力及压力导数;窜流系数和裂缝弹性储容比的变化决定了窜流段发生的早晚和程度;而基岩中气体黏度的变化使得窜流的发生稍微滞后。
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We make the following assumption for When 2 is positive definite matrix, different estimators about matrix of regression coefficients and inefficiency of Least squares estimate have been discussed in many documents. Considered 2 is nonnegative definite matrix, this thesis derives Best linear unbiased Estimate of parameter matrix B and estimable parameter function KBL under the meaning of matrix nonnegative definite and the property of maximum probability of BLUE is investigated.
当∑>0时,众多文献讨论了回归系数阵的各种估计及LSE的有效性,本文考虑了当∑≥0的情形,给出了回归系数阵B及其可估参数函数KBL的在矩阵非负定意义下的最优估计,研究了它的一个最大概率性质,并且讨论了最小二乘估计成为最佳线性无偏估计的充分必要条件,在此基础上给出了均值矩阵的最小二乘估计与BLUE的偏差估计,定义了LSE相对于BLUE的一个相对效率,并给出了它的界。
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The main results of the study are obtained as follows:1 In order to analyze and study the physical and mechanical characteristics of Lianyungang marine soft clay deeply, large numbers of basic mechanical characteristics tests and tri-axial shear tests are completed.2 In order to investigate the loaded and failure characteristics of the cement-soil, the cement-soils for the different ratio and different cure time are studied in the laboratory, and their unconfined compression tests and tri-axial shear tests are performed.3 Based on the solution of one-dimension consolidation, the one-dimension consolidation of the double-layered foundation is solved for two-grade loading in virtue of transcendental equation; Simultaneously, the one-dimension consolidation of the double-layered foundation is solved by means of Laplace transform for two-grade loading, and Stehfest numerical transform is applied in Laplace's inverse transformation; Furthermore, according to the practical foundation shapes, the consolidation models of the soil between piles and the substratum are built and solved respectively.4 The effect of each parameters on the consolidation of the double-layered foundation is discussed, and the solution of load transfer method for double-layered foundation is applied in A1-A4 section of Lian-Xu expressway. The results of calculating settlement of the double-layered consolidation theory are basic agreement with the measuring settlement results.
取得了以下几方面的研究成果:1针对连云港海相软土进行一维固结和三轴剪切试验,深入分析连云港海相软土的物理力学特性。2模拟水泥土搅拌桩施工,在室内制备不同配比、不同龄期的水泥土试样,并进行无侧限抗压试验和三轴剪切试验,揭示水泥土的受力特性及破坏特性。3运用超越方程,以双层地基一维固结解析解为基础,推导出二级加荷条件下双层地基的固结解析解;同时,通过荷载传递法并借助Laplace变换对双层地基的固结问题进行了数值求解;此外,根据实际的地基结构,建立了桩间土和下卧层的固结模型并分别进行求解分析。4分析探讨了双层地基中各参数对双层地基固结的影响程度,并运用荷载传递法的解答计算了连-徐高速公路A1-A4标水泥土搅拌桩处理段的六个断面,计算结果与实测数据有较好的一致性。
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Based on this, a new WENO difference scheme which based on Dispersion-Relation-Preserving relation is developed, and representative test cases with this scheme for computational aeroacoustics problems has been implemented and compared in order to test capability of wave capturing; In addition, WENO schemes generally do not converge at high order in the presence of contact discontinuity of Euler equations, so a conservative front tracking technique coupling WENO schemes and Level Set method to simulate the translating density profile is presented here, and numerical simulation with this technique for representative test case has been implemented and results show the desired accuracy.
本文研究了高阶精度加权基本无振荡格式及其在双曲守恒律方程中的应用,在此基础上作了两个方面的工作:一是针对高频声波问题构造出一种基于保色散关系的WENO有限差分格式,并对计算气动声学问题的代表性算例进行了大量数值实验,比较了该格式捕捉波数的能力;另外,针对高阶WENO格式在处理Euler方程的接触间断时精度有所降低的问题,研究了利用界面追踪技术Level Set方法和高阶激波捕捉WENO格式相结合的一种守恒追踪方法,并且给出有代表性的密度滑移面问题的算例,得到一致高阶精度的数值模拟结果。
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We used Aeromonas hydrophila which we separated from the diseased Paralichthys olivaceus to made a inactivated whole cell bacterin .We injected this vaccine in the mice and the Paralichthys olivaceus .Both the mice and the Paralichthys olivaceus gained a good protection of 80% and 70%.The fish with dipping immersion gained a good protection of 85%,and the incidence of disease was 6%.We detected the antibody level in the antiserum by agglutination reaction and indirect ELISA which seemed to be immunogenic crucially.We anatomized the mice then we found that all the purtenance of the immunzied mice are healty.All of this proved that the vaccine is effective.
本实验将所分离到的嗜水气单胞菌用终浓度为0.2%~0.5%的甲醛对菌体进行灭活,制备了灭活疫苗,并优化灭活疫苗的灭活条件;将制备的灭活疫苗分别注射小鼠和牙鲆,均取得了较为理想的效果,其中小鼠的免疫保护率达到80%,牙鲆的免疫保护率达到70%;采用渗透压差法大规模浸泡免疫牙鲆也取得了很好的效果,浸泡免疫过的牙鲆发病率仅为6%,攻毒后免疫保护率为85%;通过应用间接ELISA方法检测受免动物的抗血清,并将牙鲆的抗血清注射新西兰白兔,从而获得兔抗鱼血清,更便于检测,结果都表明动物体内产生了较高的抗体水平;剖检攻毒后的动物,发现免疫过的动物内脏健康无异样,表明该疫苗安全有效,从而为防治牙鲆腹水症开辟了一条新途径,也为进一步制备其基因工程疫苗奠定了基础。
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In time of realizing moderate unglue hemp, it developed a series of new products like low polymeric xylose, pectin, environmental fiberboard and organic manure that reaches delamination and multilevel use of hemp's combination and disassembly.
技术特点:1、项目基于大麻纤维和麻杆等化学组成和结构的差异,开发了环境友好的汽爆新技术,为实现大麻的清洁、高效全利用奠定了基础。2、建立的大麻清洁脱胶方法,既提高了麻皮纤维的制成率和分裂度,又不损伤纤维结构,显著提高了大麻的可纺性,是一种创新的大麻脱胶技术。3、提出了利用大麻杆无胶制备环保型纤维板的方法,解决了成本高和二次污染问题。4、该项目突破依靠单一技术或单一组分利用的技术路线,按照生态工程原理,建立了大麻产品深加工利用的技术体系和综合利用新工艺,在实现麻皮纤维适度脱胶的同时,开发了低聚木糖、果胶、环保型纤维板和有机肥料等系列新产品,达到了大麻组分的分层多级利用。
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In this paper, the basic principle and the power factor of conventional SERDS are discussed. Aiming at its shortage of low power factor, boost chopper type SERDS is adopted. The equivalent circuit of the new scheme is built up, and then vector diagram is used to analyze the power factor of the system, also the harmonic distortion of the system is discussed. The experiment device is established base on a 380F/7.5 kW induction motor and a passive soft switching scheme is applied in order to improve the working condition of IGBT. At last, the experimental results are shown.
本文在分析传统串级调速原理的基础上,对系统的功率因数进行分析;针对传统串级调速系统功率因数低的缺点,采用升压斩波式串级调速系统加以改进;建立了升压斩波式串级调速系统的等效电路并采用向量图法对该系统的功率因数进行详细分析;分析了系统的谐波情况;构建了以7.5kW/380V电机为调速对象的升压斩波式串级调速系统实验装置,给出相应的实验结果;针对斩波器中IGBT处于硬开关状态的缺点,应用无源无损软开关技术予以改善,包括对软开关电路工作原理的分析、参数的设计并给出相应的实验结果。
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On this basis, kinematics simulation of the model was used by Adams. Meanwhile,this paper also introduced the way of constraint of Differential gear and Shortcomings in the course of Adams simulation, and pr oposed a new and feasible way of establishment of gear constraint.
建立了基于UG对无级传动变速器的三维模型,在此基础上运用Adams对模型进行运动学仿真,同时介绍了在Adams仿真过程中差动轮系约束的建立方法以及还存在的缺点,并且提出了建立齿轮约束的新的可行的方法。
- 推荐网络例句
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She gently rebuff ed him, but agreed that they could be friends
她婉言拒绝了,但同意作为朋友相处。
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If in the penal farm, you were sure to be criticized.
要是在劳改农场,你等着挨绳子吧!
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Several theories about reigniting and extinguishing of the arc have been refered.
本文综合考虑了几种电弧重燃和熄灭理论。