基于探测概率的雷达网反隐身开关机模型

为提高雷达网对隐身目标的战术对抗能力,根据隐身飞机的特点,提出主战方向角概念。由主战方向角和雷达与目标的相对位置来计算雷达对隐身目标的探测概率。按照隐身目标航迹经过的每个网格,建立了基于探测概率的雷达网开关机模型,并在每个网格内选取主战雷达和助战雷达。仿真结果表明,该模型可以快速准确地评估雷达网搜索目标的能力,并为指挥员对雷达网内各部雷达进行有序的实时指挥提供有价值的参考。

一种雷达网反隐身雷达开关机模型

为了提高雷达网对隐身目标的战术对抗能力,根据隐身飞机的特点,由隐身飞机的入侵方向和雷达与目标的相对位置来计算雷达对隐身目标的探测概率,建立了基于探测概率的雷达网开关机模型,并在各网格内选取主战雷达和助战雷达.在责任区内输入一条F-117A航迹进行仿真,结果表明该模型可以为指挥员实时指挥提供参考.

基于大数据的数字电视用户关机行为预测

广电有线运营商利用双向数字电视机顶盒回传的用户收视行为数据,结合广电BOSS系统提供的媒资数据,通过采用大数据分析技术,为数字电视用户提供个性化的收视服务,极大提升了用户体验并增加了营业收入。然而,回传数据难以捕捉到电视机的状态,在机顶盒未关闭而电视机关闭的情况下,通过回传数据得到的用户收视行为是无效的,会影响大数据分析系统对用户收视行为的预估。通过分析已知的数字电视用户关闭电视机的行为特征,生成用户关机模型,从而预测无法采集到电视机关机数据的数字电视用户的关机行为,保证用户收视行为统计的有效性。

Causation mechanism of coal miners' human errors in the perspective of life events

In order to effectively decrease the safety accidents caused by coal miners’human errors,this paper probes into the causality between human errors and life events,coping,psychological stress,psychological function,physiological function based on life events’vital influence on human errors,establishing causation mechanism model of coal miners’human errors in the perspective of life events by the researching method of structural equation.The research findings show that life events have significantly positive influence on human errors,with a influential effect value of 0.7945 and a influential effect path of‘‘life events—psychological stress—psychological function—physiological function—human errors’’and‘‘life events—psychological stress—physiological function—human errors’’.

Elastodynamic modeling and joint reaction prediction for 3-PRS PKM

To gain a thorough understanding of the load state of parallel kinematic machines(PKMs), a methodology of elastodynamic modeling and joint reaction prediction is proposed. For this purpose, a Sprint Z3 model is used as a case study to illustrate the process of joint reaction analysis. The substructure synthesis method is applied to deriving an analytical elastodynamic model for the 3-PRS PKM device, in which the compliances of limbs and joints are considered. Each limb assembly is modeled as a spatial beam with non-uniform cross-section supported by lumped virtual springs at the centers of revolute and spherical joints. By introducing the deformation compatibility conditions between the limbs and the platform, the governing equations of motion of the system are obtained. After degenerating the governing equations into quasi-static equations, the effects of the gravity on system deflections and joint reactions are investigated with the purpose of providing useful information for the kinematic calibration and component strength calculations as well as structural optimizations of the 3-PRS PKM module. The simulation results indicate that the elastic deformation of the moving platform in the direction of gravity caused by gravity is quite large and cannot be ignored. Meanwhile, the distributions of joint reactions are axisymmetric and position-dependent. It is worthy to note that the proposed elastodynamic modeling method combines the benefits of accuracy of finite element method and concision of analytical method so that it can be used to predict the stiffness characteristics and joint reactions of a PKM throughout its entire workspace in a quick and accurate manner. Moreover, the present model can also be easily applied to evaluating the overall rigidity performance as well as statics of other PKMs with high efficiency after minor modifications.

Modeling of Rocks with Spatial Distributed Fractures by Random Medium Theory

By using the spectrum expanding theory of random processes and Hudson's crack model,we developed a random medium model for rocks with spatial random distributed number density of cracks. This model could connect the micro-parameters of the cracks with the macro- mechanical properties, and can be effectively applied to model the real inhomogeneous medium. Numerical example indicates that the random distribution characters could be different for different elastic constants under the same random distribution of number density of cracks. By changing the value of the autocorrelation length pair, it is possible to model the difference of the distribution in the two coordinate directions. Numerical modeling results for seismic wave propagating in rocks with random distributed fractures using a staggered high-order finite-difference (SHOFD) are also presented.

Coefficient of Partial Correlation and Its Calculation

This thesis offers the general concept of coefficient of partial correlation.Starting with regres-sion analysis,the paper,by using samples,infers the general formula of expressing coefficient of partial correlation by way of simple correlation coefficient.

Mechanical Behavior of Soybean Protein Fibers

In order to understand the relationship between the mechanical property and the effect of bleaching and dyeing to the soybean protein fibers(SPF),four mechanical models are chosen.The tensile and relaxation property of the soybean protein fibers are analyzed.The tensile and relaxation curves are fitted with the suitable model.It shows that the relaxation property of SPF is in accordance with the standard linear solid model.Estimates of the Hookean spring modulus at 8% and at 10% are different,so some structural modifications could be produced by the strain.Bleached fibers show a higher level of relaxation than raw fibers and dyed fibers.Bleaching has a remarkable influence on decreasing tenacity at break for each test modality.Knotted and looped modalities decrease fiber tenacity remarkably in all three samples.

The Crucial Role of Time in M＆A Activities： An Inductive Exploration

Mergers ＆ acquisitions （M＆As） are important strategic instruments, yet nearly half of all transactions fail, often resulting in disastrous write-offs and losses for corporations and financing institutions alike - despite promising prospects upfront. Applied research has been trying to find a ＂panacea＂ to prevent or at least predict M＆A failure, investigating motives, synergies and performance. Despite the growing unease with the stationary explanatory models in literature, research has only marginally focused on the concept of time, with inquiries into market timing and integration speed. Yet other timing concepts have been neglected in concepts so far despite early empirical evidence for their existence. The purpose of this paper is thus to identify and elaborate on the importance of further relevant theories of timing. For this, and true to the exploratory nature of the topic, the authors have chosen a qualitative comparative case study design based on existing case reports which are investigated for narrations highlighting timing concepts. This study reveals six factors which have a crucial impact on the M＆A outcome： time of acquisition, M＆A duration in its entirety, M＆A sequence, synergy chronology, frequency of acquisitions and time to step back. It contributes to theory and practice in outlining the careful attention that needs to be paid in planning in these factors to enhance the chances of a successful M＆A transaction.

Anomaly detection of hot components in gas turbine based on frequent pattern extraction

Hot components operate in a high-temperature and high-pressure environment. The occurrence of a fault in hot components leads to high economic losses. In general, exhaust gas temperature(EGT) is used to monitor the performance of hot components.However, during the early stages of a failure, the fault information is weak, and is simultaneously affected by various types of interference, such as the complex working conditions, ambient conditions, gradual performance degradation of the compressors and turbines, and noise. Additionally, inadequate effective information of the gas turbine also restricts the establishment of the detection model. To solve the above problems, this paper proposes an anomaly detection method based on frequent pattern extraction. A frequent pattern model(FPM) is applied to indicate the inherent regularity of change in EGT occurring from different types of interference. In this study, based on a genetic algorithm and support vector machine regression, the relationship model between the EGT and interference was tentatively built. The modeling accuracy was then further improved through the selection of the kernel function and training data. Experiments indicate that the optimal kernel function is linear and that the optimal training data should be balanced in addition to covering the appropriate range of operating conditions and ambient temperature. Furthermore, the thresholds based on the Pauta criterion that is automatically obtained during the modeling process, are used to determine whether hot components are operating abnormally. Moreover, the FPM is compared with the similarity theory, which demonstrates that the FPM can better suppress the effect of the component performance degradation and fuel heat value fluctuation. Finally, the effectiveness of the proposed method is validated on seven months of actual data obtained from a Titan130 gas turbine on an offshore oil platform. The results indicate that the proposed method can sensitively detect malfunctions in hot components during the early stages of a fault, and is robust to various types of interference.

An improved practical model for wear prediction of revolute clearance joints in crank slider mechanisms

A stationary clearance link algorithm(SCLA)for calculating the reaction-force of revolute clearance joints in crank slider mechanisms is proposed in this paper.The SCLA is more efficient than other algorithms of the same accuracy.Furthermore,based on the Winkler foundation model,an unsymmetrical Winkler foundation model and a double elastic layer Winkler model are proposed.By integrating a dynamic model and the unsymmetrical Winkler foundation model with Archard wear model,an improved integrated wear prediction model is also generated.A series of experiments have been performed to compare with the predicted analysis data,and the results showed a good agreement.As a real industry application,with the double elastic layer Winkler model,the integrated wear prediction model was successfully used to predict the wear depth of the joint bearing(bimetallic bearing)for the cantilever crane of a concrete pump truck of Sany Heavy Industry.

Three-dimensional dissipative stress space considering yield behavior in deviatoric plane

Naturally deposited soils are always found in the complex three-dimensional stress state.Constitutive models developed for modeling the three-dimensional mechanical behavior of soils should obey the basic laws of thermo-mechanical principles.Based on the incremental dissipation function,a new deviatoric shift stress is derived and then introduced into the existing constitutive models to describe the yield behavior in the deviatoric plane for geomaterials.By adopting the proposed shift stress,the relationship between dissipative stress tensors and true stress tensors can be established.Therefore,the threedimensional plastic strain can be calculated reasonably through the associated flow rule in the three-dimensional dissipative stress space.At the same time,three methods that are conventionally adopted for generalizing constitutive models to model the three-dimensional stress-strain relationships are examined under the thermo-mechanical framework.The TS(transformed stress)method is shown to obey the thermo-mechanical rules and the TS space adopted in TS method is actually a translational three-dimensional dissipative stress space.However,it is illustrated that the other two approaches,the method of using failure criterion directly and the method of using g()function,violate the basic rules of thermo-mechanical theories although they may bring convenience and simplicity to numerical analysis for geotechnical engineering.Comparison between model predictions and experimental data confirms the validity of the proposed three-dimensional dissipative stress space.

The Effects of Simplest Little Higgs Model on the Spin Correlations in the Top Quark Pair Production at the LHC and ILC

In the simplest little Higgs model （SLH）, we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values. At the LHC, the suppression can be over 10% for mz, 〈 750 GeV. The SLH prediction value is outside the 1σ range of the experimental data from ATLAS, and within 1σ range of the experimental data from CMS. At the ILC, the SLH can sizably suppress the tt spin correlation for mz, approaching the center-of-mass energy √s. For example, the maximal suppression can reach -22.5%, -14.5%, and -9.5% for √s = 500 Ge V, 800 Ge V, and 1000 GeV, respectively. Therefore, the tt spin correlation at the ILC can be a sensitive probe for the SLH.