ASSESSMENT OF AIRCRAFT COMBAT SURVIVABILITY ENHANCED BY COMBINED RADAR STEALTH AND ONBOARD ELECTRONIC ATTACK

The combat survivability is an essential factor to be considered in the development of recent military aircraft. Radar stealth and onboard electronic attack are two major techniques for the reduction of aircraft susceptibility. A tactical scenario for a strike mission is presented. The effect of aircraft radar cross section on the detection probability of a threat radar, as well as that of onboard jammer, are investigated. The guidance errors of radar guided surface to air missile and anti aircraft artillery, which are disturbed by radar cross section reduction or jammer radiated power and both of them are determined. The probability of aircraft kill given a single shot is calculated and finally the sortie survivability of an attack aircraft in a supposed hostile thread environment worked out. It is demonstrated that the survivability of a combat aircraft will be greatly enhanced by the combined radar stealth and onboard electronic attack, and the evaluation metho dology is effective and applicable.

恢复受CIH病毒摧毁的BIOS系统

众所周知,4月26日是计算机的灾难日。但是,偏偏今年4月26日大部分计算机使用者都没有注意,致使很多计算机遭到CIH病毒的袭击。我单位也未能幸免,一台P586同样遭到CIH病毒的袭击,而且是最惨的一种,BIOS系统和硬盘分区均被摧毁。 我单位遭CIH病毒袭击的计算机是一台Pentium 166MMX,微星MS5129主板,AMIBIOS的BIOS系统。当时的第一个想法就是希望找到一块同样主板的BIOS芯片,用热插拔法恢复已被摧毁的BIOS系统。经过一天的折腾,始终无法找到所要的BIOS芯片。难道就没有办法了吗?通过认真仔细的分析,我想同一时期的计算机其硬件配置相差不多。

1994年广西船舶交通事故分析及防范措施

一、全年事故概况 1994年度,全区共发生入级统计的船舶交通事故120起,其中重大、大事故77起,死亡4人,事故直接经济损失4358483元,与1993年对比,事故次数上升15.38％,重大、大事故上升8.45％,死亡人数下降76.47％,事故直接经济损失上升6.7％。

Space-time spreading and space-time coding for correlated frequency-selective channel in the presence of interference

The space-time spreading （SIS）, superimposed training sequences and space-time coding （STC） are adopted to obtain a closed-form of average error probability upper bound and maximum likelihood esti- mation expression for multiple input and multiple output （MIMO） correlated frequency-selective channel in the presence of interference （colored interference）. Moreover, the correlation at both ends of the wire- less link that can be incorporated equivalently into correlation at the transmit end is derived. Finally, the mean square error （MSE） of the maximum likelihood estimate is also derived.

Numerical method of slope failure probability based on Bishop model

Based on Bishop's model and by applying the first and second order mean deviations method, an approximative solution method for the first and second order partial derivatives of functional function was deduced according to numerical analysis theory. After complicated multi-independent variables implicit functional function was simplified to be a single independent variable implicit function and rule of calculating derivative for composite function was combined with principle of the mean deviations method, an approximative solution format of implicit functional function was established through Taylor expansion series and iterative solution approach of reliability degree index was given synchronously. An engineering example was analyzed by the method. The result shows its absolute error is only 0.78% as compared with accurate solution.

Quantifying the attribution of model bias in simulating summer hot days in China with IAP AGCM 4.1

Using lAP AGCM simulation results for the period 1961-2005, summer hot days in China were calculated and then compared with observations. Generally, the spatial pattern of hot days is reasonably reproduced, with more hot days found in northern China, the Yangtze and Huaihe River basin, the Chuan-Yu region, and southern Xinjiang. However, the model tends to overestimate the number of hot days in the above-mentioned regions, particularly in the Yangtze and Huaihe River basin where the simulated summer-mean hot days is 13 days more than observed when averaged over the whole region, and the maximum overestimation of hot days can reach 23 days in the region. Analysis of the probability distribution of daily maximum temperature （Trnax） suggests that the warm bias in the model-simulated Tmax contributes largely to the overestimation of hot days in the model. Furthermore, the discrepancy in the simulated variance of the Tmax distribution also plays a non- negligible role in the overestimation of hot days. Indeed, the latter can even account for 22% of the total bias of simulated hot days in August in the Yangtze and Huaihe River basin. The quantification of model bias from the mean value and variability can provide more information for further model improvement.

Estimating extreme temperature differences in steel box girder using long-term measurement data

The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge,the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were summarized.The probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 years.Finally,the temperature difference models in cross-section area were proposed for bridge thermal design.The results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are considerable.All the positive and negative temperature differences can be described by the weighted sum of two Weibull distributions.The maximum positive and negative horizontal temperature differences in top plate are 10.30 ℃ and -13.80 ℃,respectively.And the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30 ℃ and-3.70 ℃,respectively.For bridge thermal design,there are two vertical temperature difference models between top plate and bottom plate,and six horizontal temperature difference models in top plate.

Pairwise codeword error probability for coded atmospheric optical communication systems

To study the performance of various error-control coding schemes,exact expressions and upper bounds on the pairwise codeword error probability(PEP)for several modulation schemes(OOK,SC-BPSK,BPPM)used in atmospheric optical communication systems are derived.To simplify the computation,this research was under the assumption of weak turbulence.Moreover,by simulation of expressions,the performances of PEP in different modulation schemes are compared and the best one of them is given.

ERROR IMPROVEMENT OF TEMPORAL DISCRETIZATION IN TDFEM FOR ELECTROMAGNETIC ANALYSIS

Integral method is employed in this paper to alleviate the error accumulation of differential equation discretization about time variant t in Time Domain Finite Element Method (TDFEM) for electromagnetic simulation. The error growth and the stability condition of the presented method and classical central difference scheme are analyzed. The electromagnetic responses of 2D lossless cavities are investigated with TDFEM; high accuracy is validated with numerical results presented.

Complementary system-theoretic modelling approach for enhancing hydrological forecasting

Hydrologic models generally represent the most dominant processes since they are mere simplifications of physical reality and thus are subject to many significant uncertainties. As such, a coupling strategy is proposed. To this end, the coupling of the artificial neural network （ANN） with the Xin＇anjiang conceptual model with a view to enhance the quality of its flow forecast is presented. The approach uses the latest observations and residuals in runoff/discharge forecasts from the Xin＇anjiang model. The two complementary models （Xin＇anjiang ＆ ANN） are used in such a way that residuals of the Xin＇anjiang model are forecasted by a neural network model so that flow forecasts can be improved as new observations come in. For the complementary neural network, the input data were presented in a patterned format to conform to the calibration regime of the Xin＇anjiang conceptual model, using differing variants of the neural network scheme. The results show that there is a substantial improvement in the accuracy of the forecasts when the complementary model was operated on top of the Xin＇anjiang conceptual model as compared with the results of the Xin＇anjiang model alone.

Probabilistic Chain Teleportation of a Qutrit-State

We investigate chain teleportation of a qutrit-state via the non-maximally two-qutrit entangled channels.For the case of four parties,the efficiencies of two chain teleportation protocols,the separate chain teleportation protocol(SCTP),and the global chain teleportation protocol (GCTP),are calculated.In SCTP the errors are corrected betweenevery step while in GCTP the errors are corrected only at the end.Furthermore,we present a piecewise global chainteleportation protocol (PGCTP) for keeping away from the inconvenience of error-correction of GCTP.We show thatPGCTP is more efficient than SCTP.

Backlash analysis of a new planetary gearing with internal gear ring

Due to low carrying capacity and short life of current ring reducer,we proposed a new planetary gearing with internal gear ring,which consisted of two stages.One was an involute planetary drive and the other was an N-type planetary drive with small teeth difference.The kinematic calculation was conducted based on the analysis of structural composition and working principle.Formulas of backlash calculation for the new planetary gearing were derived by using probabilistic theory and the analytical model was created at the same time.Then,main factors that affect the systematic backlash were introduced and the effects of manufacture error,misaligments and roller bearing parameters on the distribution of backlash were presented.The influence of gear backlash on systematic return difference was performed based on the backlash mathematic model proposed.The results show that the backlash is a little large,of which the backlash of bearing takes a greater part than two gearing stages.So we presented some practical methods to reduce the systematic backlash.

STATISTICAL PROBABILITY BASED ALGORITHM FOR EXTRACTING FEATURE POINTS IN 2-DIMENSIONAL IMAGE

An algorithm for automatically extracting feature points is developed after the area of feature points in 2-dimensional (2D) imagebeing located by probability theory, correlated methods and criterion for abnormity. Feature points in 2D image can be extracted only by calculating standard deviation of gray within sampled pixels area in our approach statically. While extracting feature points, the limitation to confirm threshold by tentative method according to some a priori information on processing image can be avoided. It is proved that the proposed algorithm is valid and reliable by extracting feature points on actual natural images with abundant and weak texture, including multi-object with complex background, respectively. It can meet the demand of extracting feature points of 2D image automatically in machine vision system.

A NOVEL INTEGER FREQUENCY OFFSET ESTIMATOR FOR OFDM

One of the principal disadvantages of Orthogonal Frequency Division Multiplexing (OFDM) is very sensitive to carrier frequency offset. The integer frequency offset has no effect on the orthogonality among the subcarriers, but it causes a circular shift and phase rotation of the received data symbols sequence, resulting in a Bit Error Rate(BER) of 0.5. In this paper,a novel integer frequency offset estimator for OFDM is derived based on maximum likelihood estimation technique and exploration of the differential relation between two consecutive OFDM data symbol sequences in frequency domain. Its performance is compared with the conventional method by computer simulations for the additive white Gaussian noise channel and a multipath fading channel. Simulation results show that the performance of the proposed estimator is better than the conventional estimator.

Probability density function and estimation for error of digitized map coordinates in GIS

Traditionally, it is widely accepted that measurement error usually obeys the normal distribution. However, in this paper a new idea is proposed that the error in digitized data which is a major derived data source in GIS does not obey the normal distribution but the p-norm distribution with a determinate parameter. Assuming that the error is random and has the same statistical properties, the probability density function of the normal distribution, Laplace distribution and p-norm distribution are derived based on the arithmetic mean axiom, median axiom and p-median axiom, which means that the normal distribution is only one of these distributions but not the least one. Based on this ideal distribution fitness tests such as Skewness and Kurtosis coefficient test, Pearson chi-square chi(2) test and Kolmogorov test for digitized data are conducted. The results show that the error in map digitization obeys the p-norm distribution whose parameter is close to 1.60. A least p-norm estimation and the least square estimation of digitized data are further analyzed, showing that the least p-norm adjustment is better than the least square adjustment for digitized data processing in GIS.

Framework Definitions of Effects and Phenomena and Examples in Differential and Difference Equations

Framework definitions of earlier informally used notions of effect and phenomenon are proposed, examples of their role in developing mathematics are given. Phenomena of singular cycle and deepening boundary layer in the theory of singularly perturbed differential equations and ancient popular synergetic process described by system of random difference equations are presented.

Dynamic Reliability Evaluation of Double-Layer Cylindrical Latticed Shell under Multi-Support Excitations

To overcome the excessive computational cost and/or bad accuracy of traditional approaches,the probabilistic density evolution method(PDEM) is introduced.The dynamic reliability of a double-layer cylindrical latticed shell is evaluated by applying PDEM and Monte Carlo Method(MCM) respectively,and four apparent wave velocities(100 m/s,500 m/s,800 m/s and 1 200 m/s) and five thresholds(0.1 m,0.2 m,0.3 m,0.4 m and 0.5 m) are taken into consideration.Only the difference between threshold and maximal deformation...

Estimating Probability of Instability of Haulage Drift with Respect to Mining Sequences

Haulage drifts play a vital role in providing personnel and equipment access to ore extraction areas for mine production. Thus, their stability is of crucial importance during the life of a mine plan. Many Canadian mines use longhole mining methods or one of its variants. These methods require access to the orebody through haulage drifts on multiple levels. This paper examines the stability of mine haulage drifts with respect to planned mining sequence. A case study of an underground mine is presented. The case study examines # l Shear East of the Garson Mine in Sudbury, Ontario. A two-dimensional, elastoplastic, finite difference model （FLAC 2D） is developed for a haulage drift situated 1.5 km below surface in the footwall of the orebody. The stability of the haulage drift is evaluated in terms of the spread of yield zones into the rockmass due to nearby mining activities. The performance of the drift stability is evaluated at various mining stages, employing the RMC （Random Monte-Carlo） technique in conjunction with finite difference modeling to study the probability of unsatisfactory performance of the drift. The results are presented and categorized with respect to probability, instability and mining stage.

The Development and Influence of RCPS Instructions to Promote Students＇ Scientific Learning Motivation and Scientific Concept Learning

This research aims at developing RCPS （revised creative problem solving） teaching model, besides the authors designed the instructions of chemical reaction to promote eight grade students＇ scientific learning motivation and scientific concept learning. We adopted quasi-experiment study, the experimental group and controlled group all 28 students were chose, go on the parameter is analyzed together compared with textbook instructions, scale of scientific learning motivation and test of scientific conception learning were used for the two groups in prior test and post test, then they used statistical ANCOVA （analysis of covariance） to analyze the differences between the two teaching models. The result of this study finds that RCPS teaching model improved student＇s scientific learning motivation and learning scientific concept was superior to textbook instructions in controlled group, p = 0.001 （〈 0.01）, and all with high experimental treatment effects （〉 0.14）. The study also proposes that when RCPS teaching model was applied to scientific concept teaching, RCPS teaching model should be joined the conception introducing stage, and pay attention to students＇ scientific learning motivation.

Moderate deviations and hypothesis testing for signal detection problem

Abstract We use moderate deviations to study the signal detection problem for a diffusion model. We establish a moderate deviation principle for the log-likelihood function of the diffusion model. Then applying the moderate deviation estimates to hypothesis testing for signal detection problem we give a decision region such that its error probability of the second kind tends to zero with faster speed than the error probability of the first kind when the error probability of the first kind is approximated by e-ατ（T）, where α〉 0, τ（T） = o（T） and τ（T）→∞ as the observation time T goes to infinity.