Evaluation of Generalized Error Function via Fast-Converging Power Series

A generalized form of the error function, Gp(x)=pΓ(1/p)∫0xe−tpdt, which is directly associated with the gamma function, is evaluated for arbitrary real values of p>1and 0x≤+∞by employing a fast-converging power series expansion developed in resolving the so-called Grandi’s paradox. Comparisons with accurate tabulated values for well-known cases such as the error function are presented using the expansions truncated at various orders.

Real-Time Information System of Power Plant Based on B/S Computing Mode

This paper introduces the system structure and work principle of the upgraded real time information system in Wangting Power Plant, and then expounds the realization way and function features of this system on B/S computing mode. The results of field application show the new system has good capability, reliability and expandability.

基于s-Power级数的对数螺线多项式逼近表示

目的为得到对数螺线的多项式逼近表示。方法利用s-Power级数,也就是泰勒两点展开的模式,得到它的多项式逼近表示。结果截断s-Power级数的前k项,就得到了k阶埃尔米特插值,也就是(2k+1)次的具有和给定区间对数螺线相同k阶端点导数的多项式曲线。通过分段拼接就得到了在拼接点具有Ck连续的Hermite B样条曲线。结论该方法计算简单,并且通过提高次数,可得到高精度逼近,是Christoph Baumgarten等人三次有理样条曲线逼近法的更合适的替代。

高压管汇材料疲劳性能测试及P-S-N模型曲线的拟合

高压管汇作为压裂设备中的主要易损件之一,其失效危害较大。它的失效原因主要是疲劳、冲蚀、腐蚀或者材料缺陷引起的刺漏和爆裂,其中尤以疲劳失效最不可预估。目前,对于高压管汇材料的疲劳性能研究不够深入,为解决高压管汇材料疲劳寿命的准确描述问题,以某国产高压管汇材料为例,进行了一系列疲劳试验,并基于试验数据,采用多种分布模型和不同S-N模型进行拟合分析,得出综合评价拟合能力最强的P-S-N模型。结果表明,该材料在中长疲劳寿命区,Weibull三参数模型在7级应力水平下综合评价能力最好;在存活率分别为50%、90%、99%、99.9%时,指数S-N模型的拟合系数均大于0.98,拟合能力最好。得出的P-S-N模型曲线可以为高压管汇的疲劳寿命以及安全设计提供依据。

Identification of voltage sag source location using S and TT transformed disturbance power

An alternative method was introduced for voltage sag source location based on S and TT transformed disturbance powers. It is done to avoid the wrong and inconclusive detection of conventional disturbance power method proposed in the literature. Unlike in the case of the traditional method, the proposed method first transforms the recorded voltage and current during the sag event to some special features before calculating the new version of disturbance powers. The effectiveness of the proposed method has been verified through simulation and actual data from an industrial power system. The results show that the presented method can correctly detect the location of voltage sag source.

Information content method for evaluating diagnostic tests and its comparison of power with other methods

This paper derives the variance of the information content and develops its statistical inference method. We describe the relations between information content and sensitivity, specificity, efficiency, prevalence rate. If sensitivity, specificity and efficiency are fixed, the closer to 0. 5 the prevalence rate is, the more the information content. If prevalence rate and efficiency are fixed, the closer to each other the sensitivity and specificity are, the more the information content. We compare the power of information content method, efficiecy test, Youden's index test and kappa coefficient method. The information content method has higher power than the other methods in most conditions. It is especially sensitive to the difference between two sensitivities. It comes to conclusion that the information content method has more virtues than the other methods mentioned in this paper.

Evaluation of axial length/total corneal refractive power ratio as a potential marker for ocular diagnosis of Marfan’s syndrome in children

AIM:To investigate whether the axial length(AL)/total corneal refractive power(TCRP)ratio is a sensitive and simple factor that can be used for the early diagnosis of Marfan’s syndrome(MFS)in children.METHODS:The relationship between the AL/TCRP ratio and the diagnosis of MFS for 192 eyes in 97 children were evaluate.The biological characteristics,including age,sex,AL,and TCRP,were collected from medical records.Receiver operating characteristic(ROC)curve analysis was performed to investigate whether the AL/TCRP ratio effectively distinguishes MFS from other subjects.The Youden index was used to re-divide the whole population into two groups according to an AL/TCRP ratio of 0.59.RESULTS:Of 96 subjects(mean age 7.46±3.28 y)evaluated,56(110 eyes)had a definite diagnosis of MFS in childhood based on the revised Ghent criteria,41(82 eyes)with diagnosis of congenital ectopia lentis(EL)were included as a control group.AL was negatively correlated with TCRP,with a linear regression coefficient of-0.36(R2=0.08).A significant correlation was found between age and the AL/TCRP ratio(P=0.023).ROC curve analysis showed that the AL/TCRP ratio distinguished MFS from the other patients at a threshold of 0.59.MFS patients were present in 24/58(41.38%)patients with an AL/TCRP ratio of≤0.59 and in 34/39(87.18%)patients with an AL/TCRP ratio of>0.59.CONCLUSION:An AL/TCRP ratio of>0.59 is significantly associated with the risk of MFS.The AL/TCRP ratio should be measured as a promising marker for the prognosis of children MFS.Changes in the AL/TCRP ratio should be monitored over time.

Power Flex700S变频器在干熄焦提升机中的应用

济钢150t、160t干熄焦提升机控制系统均采用AB公司的RSLogix5000控制系统,提升机变频器采用的是PowerFlex700S系列产品,变频器与控制系统之间通过ControlNet模块进行连接通讯,采用端子控制方式,动作流程更加平稳,实现了良好的人机界面功能,保证了干熄焦高效安全稳定运行。

Investment risk analysis of China's wind power industry based on pre-assessment matrix

Wind energy is a clean and sustainable energy, and wind power does not rely on fossil fuels. So there is no fuel price risk, and it, of course, does not include the environmental costs, such as carbon emissions. Because of these unique advantages, wind power has gradually become an important part of the strategy of sustainable development in China. Now with the growing voices on global greenhouse gas emission reduction, and as a clean and efficient energy, wind power has huge potential in combating climate change, energy security pressures and the needs for energy. Wind power in China began to develop from the 1980s. In the first 20 years, the speed of development was slow; but since 2004, it has had an extremely rapid growth.This paper, in order to study the development mechanism of China＆amp;amp;amp;#39;s wind power industry, investigated and analyzed the status quo of wind power industry in China, and then found that （1） the development trend of wind power industry in China appears exponential growth; （2） China＆amp;amp;amp;#39;s installed capacity of wind power is still smaller than that os some other countries; （3） new subsidy policies bring developing opportunities to wind power industry in China; （4） the sectors of wind power industry are in unbalanced growing; （5） the owners of proposed wind farms are too optimistic though the built wind farm had many problems. In addition, by using the methodology of Game Theory, this paper has also constructed the matrix of pre-assessing risks of China＆amp;amp;amp;#39;s wind power industry to further discuss the potential risk factors within China＆amp;amp;amp;#39;s wind power industry as risk factors of wind farm construction, risk factors of production of wind turbines, risk factors of parts and components manufacturing industry under risk indicators like R＆amp;amp;amp;amp;D, patents, the domestic policy, the international policy, the quality of products and the market regulation, in order to provide a scientific assessment and self-assessment tool for investors or implementers, and also to promote the further development of the wind power industry.

经验小波变换和改进S变换结合的电能质量检测与识别方法

为分析不确定干扰因素影响下的实际电力网络电能质量问题,提出一种经验小波变换(EWT)和改进S变换相结合的电能质量检测与识别方法。该方法一方面利用EWT联合归一化直接正交(NDQ)算法和奇异值分解(SVD)算法准确提取调幅-调频分量的频率、幅值和时间参数,另一方面考虑到EWT算法在高噪声环境下瞬时幅值波动的问题,引入改进S变换提取高噪声干扰下的电能质量扰动时频信息,最后,基于EWT和改进S变换提取的扰动特征向量,利用基于改进粒子群优化算法(IPSO)优化支持向量机(SVM)的电能质量扰动识别分类器实现扰动类型的精确识别。仿真和实验表明所提方法在复合扰动识别分类时平均识别准确率为93.23%,且能够准确识别4种实测扰动信号。

Electrical Power Losses in a Photovoltaic Solar Cell Operating under Partial Shading Conditions

The aim of this paper is to determine the power losses recorded by a PV generator operating under partial shading conditions. These losses are evaluated through two distinct methods. The first method is based on mathematical modeling, while the second is based on Simulink’s physical model. The losses recorded are considerable and increase as a function of the increase in the percentage of shading up to a limit value where they become constant in the case where an ideal by-pass diode is connected in parallel with the modules. This limit value is non-existent in the case where the bypass diode is not ideal, which in fact corresponds to the real model. However, it emerges that the power losses are minimized in a PV system comprising bypass diodes, in particular in the case where the partial shading is considerable.

A WEIGHTED FEATURE REDUCTION METHOD FOR POWER SPECTRA OF RADAR HRRPS

Feature reduction is a key process in pattern recognition. This paper deals with the feature reduction methods for a time-shift invariant feature, power spectrum, in Radar Automatic Target Recognition (RATR) using High-Resolution Range Profiles (HRRPs). Several existing feature reduction methods in pattern recognition are analyzed, and a weighted feature reduction method based on Fisher's Discriminant Ratio (FDR) is proposed in this paper. According to the characteristics of radar HRRP target recognition, this proposed method searches the optimal weight vector for power spectra of HRRPs by means of an iterative algorithm, and thus reduces feature dimensionality. Compared with the method of using raw power spectra and some existing feature reduction methods, the weighted feature reduction method can not only reduce feature dimensionality, but also improve recognition performance with low computation complexity. In the recognition experiments based on measured data, the proposed method is robust to different test data and achieves good recognition results.

Future Expectation for China’s Nuclear Power

China: the future of nuclear powerWang Yonggan: In terms of the highlighted issue ofenergy security, oil is of paramount importance, coal isthe foundation and electricity is the pivot according

Power cost minimization in data centers Via Lyapunov optimization

With the advent of big data,the demand for computing has been increasing in a very large scale for the past decade,so geographically distributed data centers are erected in the direction of cloud computing development. A Lyapunov optimization approach is considered for the problem of minimizing energy cost for distributed Internet data centers( IDCs). By capturing the power cost of servers and cooling systems,the Lyapunov optimization technique is formulated to design a decisive strategy that offers provable power cost minimization and Qo S guarantees. The algorithm performance and effectiveness are validated via simulations driven by real world traces.

Wind Power Potential in Interior Alaska from a Micrometeorological Perspective

The wind power potential in Interior Alaska is evaluated from a micrometeorological perspective. Based on the local balance equation of momentum and the equation of continuity we derive the local balance equation of kinetic energy for macroscopic and turbulent systems, and in a further step, Bernoulli’s equation and integral equations that customarily serve as the key equations in momentum theory and blade-element analysis, where the Lanchester-Betz-Joukowsky limit, Glauert’s optimum actuator disk, and the results of the blade-element analysis by Okulov and Sorensen are exemplarily illustrated. The wind power potential at three different sites in Interior Alaska (Delta Junction, Eva Creek, and Poker Flat) is assessed by considering the results of wind field predictions for the winter period from October 1, 2008, to April 1, 2009 provided by the Weather Research and Forecasting (WRF) model to avoid time-consuming and expensive tall-tower observations in Interior Alaska which is characterized by a relatively low degree of infrastructure outside of the city of Fairbanks. To predict the average power output we use the Weibull distributions derived from the predicted wind fields for these three different sites and the power curves of five different propeller-type wind turbines with rated powers ranging from 2 MW to 2.5 MW. These power curves are represented by general logistic functions. The predicted power capacity for the Eva Creek site is compared with that of the Eva Creek wind farm established in 2012. The results of our predictions for the winter period 2008/2009 are nearly 20 percent lower than those of the Eva Creek wind farm for the period from January to September 2013.

Disclosure of Duke's Power in My Last Duchess Through Analysis of Transitivity

This thesis attempts to analyze the presentation of Duke's power in Robert Browning's My Last Duchess through theory of transitivity in functional stylistics. Through transitivity analysis, Duke's dominating position will be revealed, and the thematic significance and language features of this poem would be shed light upon as well.

Constant Power Model in Arm Rotation—A New Approach to Hill’s Equation

The purpose of this study was to further develop the constant power model of a previous study and to provide the final solution of Hill’s force-velocity equation. Forearm and whole arm rotations of three different subjects were performed downwards (elbow and shoulder extension) and upwards (elbow and shoulder flexion) with maximum velocity. These arm rotations were recorded with a special camera system and the theoretically derived model of constant maximum power was fitted to the experimentally measured data. The moment of inertia of the arm sectors was calculated using immersion technique for determining accurate values of friction coefficients of elbow and whole arm rotations. The experiments of the present study verified the conclusions of a previous study in which theoretically derived equation with constant maximum power was in agreement with experimentally measured results. The results of the present study were compared with the mechanics of Hill’s model and a further development of Hill’s force-velocity relationship was derived: Hill’s model was transformed into a constant maximum power model consisting of three different components of power. It was concluded that there are three different states of motion: 1) the state of low speed, maximal acceleration without external load which applies to the hypothesis of constant moment;2) the state of high speed, maximal power without external load which applies to the hypothesis of constant power and 3) the state of maximal power with external load which applies to Hill’s equation. This is a new approach to Hill’s equation.

Large Power Transformer Fault Diagnosis and Prognostic Based on DBNC and D-S Evidence Theory

Power transformer is a core equipment of power system, which undertakes the important functions of power transmission and transformation, and its safe and stable operation has great significance to the normal operation of the whole power system. Due to the complex structure of the transformer, the use of single information for condition-based maintenance (CBM) has certain limitations, with the help of advanced sensor monitoring and information fusion technology, multi-source information is applied to the prognostic and health management (PHM) of power transformer, which is an important way to realize the CBM of power transformer. This paper presents a method which combine deep belief network classifier (DBNC) and D-S evidence theory, and it is applied to the PHM of the large power transformer. The experimental results show that the proposed method has a high correct rate of fault diagnosis for the power transformer with a large number of multi-source data.

CALCULATIONS OF BIVARIATE SPLINES——Ⅰ. Truncated Powers and BM-Splines in S_2~1, (?)2 and S_4~2,(?)_2

Examining the B-coefficient relations between two adjacent s-simplicies with given smoothness requirements, we find a compromise technique between btp-coefficients and B-coefficients to calculate a bivariate locally supported spline, give another proof of the BM-splines in S_(100)(4d, 3d-1, △_2) and establish the BM-splines in S_2~1, and S_4,

Japan’s Politics and Diplomacy after DPJ Took Power

Great changes occurred to the Japanese power structure as DPJ had taken power. The new government in Japan is now headed by DPJ and its alliance–Social Democratic Party and People's New Party, substituting for LDP-Komeito coalition government, an alternation of two conservative parties, though not in a strict sense of the two-party alternation. The election intensified the conservative politics in general, though different from the hawk conservative force in the post-cold war period. The Japanese political currents see a trend of 'de-rightwardization'. This will help to improve Japan’s relations with its Asian neighbors. Yukio Hatoyama calls for building 'fraternity society' and fostering 'fraternity' spirit in diplomatic affairs. He is for the view of attaching equal importance to U.S. and Asia.