用极大似然法研究部分熔透十字接头疲劳性能

利用极大似然法测试疲劳寿命曲线,研究未熔透尺寸对十字接头疲劳强度的影响。应用有限元方法,可确定疲劳裂纹的开裂位置(焊根或焊趾)。经疲劳试验表明,极大似然法实用性及曲线拟合合理性较好,而且十字焊接接头存在一个临界未熔透尺寸,低于临界值,承受轴向载荷作用的焊接接头疲劳强度不会受到影响。

关于半参数广义线性模型的惩罚似然估计

本文对文[1]给出的一类半参数广义线性模型(semi-paramctric GLM),利用惩罚似然方法得到参数和非参数函数的惩罚似然估计。同时指出极小惩罚似然估计与惩罚加权最小=乘估计等价。

术语翻译标准体系刍议

术语翻译的本质及术语特点决定了术语翻译应遵循"极似"标准。以"极似"为核心,以术语形式、术语内容、术语风格为实现维度构筑术语翻译标准体系。译者通过对原语术语的操作,转移内容,更换形式,可实现双语术语的"极似"。

(bt)性质

若T满足σ(T)\σvw(T)=p00(T),则称T有(bt)性质。本文主要研究了(bt)性质,具体研究了(bt)性质与其它Weyl型定理之间的关系,并给出了(bt)性质成立的条件及它与SVEP之间的关系。

可靠性试验数据的统计分析法

应用统计理论方法分析可靠性试验数据具有深远的理论意义,在实践中有良好的作用.作者就对之作了些较深入的思考,并展开了科学论述.

Life prediction for vacuum fluorescent display using maximum likelihood estimation

In order to obtain the life information of the vacuum fluorescent display （VFD） in a short time, a model of constant stress accelerated life tests （CSALT） is established with its filament temperature increased, and four constant stress tests are conducted. The Weibull function is applied to describe the life distribution of the VFD, and the maximum likelihood estimation （MLE） and its iterative flow chart are used to calculate the shape parameters and the scale parameters. Furthermore, the accelerated life equation is determined by the least square method, the Kolmogorov-Smirnov test is performed to verify whether the VFD life meets the Weibull distribution or not, and selfdeveloped software is employed to predict the average life and the reliable life. Statistical data analysis results demonstrate that the test plans are feasible and versatile, that the VFD life follows the Weibull distribution, and that the VFD accelerated model satisfies the linear Arrhenius equation. The proposed method and the estimated life information of the VFD can provide some significant guideline to its manufacturers and customers.

Percentiles Estimation for a Response Distribution

To estimate percentiles of a response distribution, the transformed response rule of Wetherill and Robbins-Monro sequential design were proposed under Log-Logistic model. Based on responses data, a necessary and sufficient condition for the existence of maximum likelihood estimators and then the calculating formula were presented. After a simulation study, the proposed approach was applied to 65# detonator. Numerical results showed that estimators of percentiles from the proposed approach are robust to the parametric models lacking information on the original response distribution.

变系数广义线性模型的变系数与变离差估计

本文提出了变系数广义线性模型中变系数与变离差的局部加权极大似然估计,同时通过数值模拟来说明这种方法的可行性。.

Reliability evaluation for Weibull distribution under multiply type-? censoring

The multiply type-I censoring represented that all units in life test were terminated at different times. For estimations of Weibull parameters, it was easy to compute the maximum likelihood estimation （MLE） and least-squares estimation （LSE） while it was hard to build confidence intervals （CI）. The concept of generalized confidence interval （GCI） was introduced to build CIs of parameters under multiply type-I censoring. Further, GCI based on LSE and GCI based on MLE were proposed. It is mathematically proved that the former is exact and the latter is approximate. Besides, a Monte Carlo simulation study and an illustrative example also Ran out that the GCI method based on LSE yields rather satisfactory results by comparison with the ones based on MLE. It should be clear that the GCI method is a sensible choice to evaluate reliability under multiply type-I censoring.

AN ADAPTIVE SPECKLE SUPPRESSION AND EDGE ENHANCEMENT TECHNIQUE

Speckle degrades severely the quality of medical B-scan ultrasonic images, especiallyit blurs edges and details of images. An adaptive speckle suppression and edge enhancementmethod based on Nakagami distribution is presented. The statistics of log-compressed echo im-ages is derived for Nakagami distribution. An adaptive filter based on local statistical propertyof speckle is designed. The stick technique that utilizes sticks with different sizes and variousorientations is applied to locally approximate certain linear features of image. The local regionis a stick instead of a usual window, the orientation of sticks is decided by hypothesis test op-timizing method and the length of sticks is obtained by region growing technique. Performanceof the new method has been tested on the phantom and ultrasound images of pig muscle andechocardiographic. The results show that the technique effectively reduces the speckle noise whilepreserving and enhancing the tissue edge and resolvable details.

Gauge Invariance of a Time-Dependent Harmonic Oscillator in Magnetic Dipole Approximation

A manifestly gauge-invariant formulation of non-relativistic quantum mechanics is applied to the case of time-dependent harmonic oscillator in the magnetic dipole approximation. A general equation for obtaining gauge-invariant transition probability amplitudes is derived.

CHANNEL ESTIMATION OF MULTI-RATE DS-CDMA SIGNALS IN SLOW FADING MULTIPATH CHANNELS

In Direct-Sequence Code Division Multiple Access(DS-CDMA) mobile communi-cation systems, it is very important to obtain accurate estimation of the channel parameters,especially that of the propagation delay. But the near-far problem may make the estimationcomplicated and can degrade the estimation performance significantly. In this paper, an efficientMaximum Likelihood (ML) method is presented for channel parameter estimation of multi-rateDS-CDMA systems in slow fading multipath channels in a near-far scenario. The algorithmextended the ML approach to multi-rate DS-CDMA systems, and proposes decomposing a multi-dimensional optimization problem into a series of one-dimensional optimization and has improvedcomputational efficiency. Theoretical analysis and numerical examples show that the estimatorproposed is effective and near-far resistant.

An Approximate M-estimation for the Parameters of Mixed Regression Model

In this paper, to keep scale inveriance, we propose an approximate M-estrmation for the mixed regression model and show consistency of the estimation under weaker conditions than that in [1].

The Wisdom of the Many and Fichte＇s ＂We＂

In order to consider the Wisdom of the Many, one has to reconsider Aristotle＇s statement about the source of a nation-state concerning political ＂gregarism＂--how it is called today, and why this belongs to the essentials of political constitution. Beforehand, this concept should not provide an instance of theoretical indulgence for emotional concepts or alike. Then, this statement will have to be confronted with the core argument of the Wisdom of the Many, together with the interpretation of Waldron. It will be interpreted as the counterpart of gregarism： When several people find together a solution, which eventually overrules that of the （few） expert（s）, they rely upon a common focus or an instance of polar consciousness. This includes the final question if the shared consciousness-or the polarity condition-is not able to also dominate and manifest within a group of experts, of those sufficiently erudite. As a token of possible evidence, the answer is given with Fichte, his lecture of the Science of Knowledge of 1804 by reason of the succinct reliance upon the plural ＂We.＂

Analysis of Electrogastrograms of Elderly Gastrectomized Subjects by Using Maximum Lyapunov Exponent

Not much data are available regarding the electrical activity in the stomachs and intestines of elderly gastrectomized patients The purpose of this study was to determine the feasibility of using a complex dynamic method to analyze the electrogastrograms （EGGs） of healthy young, healthy elderly, and gastrectomized elderly male individuals. The authors analyzed the EGGs by using the maximum Lyapunov exponent （MLE）, which is one of the indices of the chaotic characteristics of time series. Significant differences were observed between the MLEs estimated from the, EGGs of the young and elderly individuals for most of the temporal intervals. The authors＇ data indicate that the EGGs of elderly gastrectomized subjects might be distinguished from the EGGs of healthy elderly individuals on the basis of the MLE distribution.

Magnetism and Sound Velocities of Iron Carbide （Fe3C） under Pressure

The elastic property and sound velocity of FeaC under high pressure are investigated by using the spin-polarized generalized gradient approximation within density-functional theory. It is found that the magnetic phase transition from the ground ferromagnetic （FM） state to the nonmagnetic （NM） state occurs at ～73 GPa. Based on the predicted Hugoniot of Fe3C, we calculate the sound velocities of FM-Fe3C and NM-Fe3C from elastic constants. Compared with pure iron, NM-FeaC provides a better match of compressional and shear sound velocities with the seismic data of the inner core, supporting carbon as one of the light elements in the inner core.

A novel robust adaptive controller for EAF electrode regulator system based on approximate model method

The electrode regulator system is a complex system with many variables, strong coupling and strong nonlinearity, while conventional control methods such as proportional integral derivative （PID） can not meet the requirements. A robust adaptive neural network controller （RANNC） for electrode regulator system was proposed. Artificial neural networks were established to learn the system dynamics. The nonlinear control law was derived directly based on an input-output approximating method via the Taylor expansion, which avoids complex control development and intensive computation. The stability of the closed-loop system was established by the Lyapunov method. The current fluctuation relative percentage is less than ±8% and heating rate is up to 6.32 ℃/min when the proposed controller is used. The experiment results show that the proposed control scheme is better than inverse neural network controller （INNC） and PID controller （PIDC）.

全译求似研究

大部分情况下,译作与原作难以相等,只能相似。就层次而言,译作与原作之似可分为近似和胜似。前者占主导地位,后者占次要地位。就类型而言,译作与原作之似可分为形似、意似与神似。意似是基本要求,形意皆似是更高追求,神似是理想状态。要做到译作似于原作,首先要准确理解原作,其次要灵活运用不同的全译方法与技巧,采用地道的译语形式准确完整地传达原作意义,曲尽其妙地传达原文风格。

Analysis of seasonal signals and long-term trends in the height time series of IGS sites in China

The seasonal signal and long-term trend in the height time series of 10 IGS sites in China are investigated in this paper. The offset detection and outlier removal as well as the removal of common mode error are performed on the raw GPS time-series data developed by the Scripps Orbit and Permanent Array Center(SOPAC). The seasonal-trend decomposition procedure based on LOESS(STL) is utilized to extract precise seasonal signals, followed by an estimation of the long-term trend with the application of maximum likelihood estimation(MLE) to the seasonally adjusted time series. The Up-compo- nents of all sites are featured by obvious seasonal variations, with significant phase and amplitude modulation on some sites. After Kendall's tau test, a significant trend(99% confidence interval) for all sites is achieved. Furthermore, the trends at sites TCMS and TNML have significant changes at epochs 2009.5384 and 2009.1493(95% confidence interval), respectively, using the Breaks For Additive Seasonal and Trend test. Finally, the velocities and their uncertainties for all sites are estimated using MLE with the white noise plus flicker noise model. And the results are analyzed and compared with those announced by SOPAC. The results obtained in this paper have a higher precision than the SOPAC results.

A novel joint navigation state error discriminator based on iterative maximum likelihood estimation

To break through the limitations of traditional discriminators used in vector tracking loops, this paper presents an iterative maximum likelihood estimation(IMLE) method for extracting navigation state errors from multi-satellite signals. The IMLE method takes into account both computational cost and estimation accuracy. The associated gradient vector and Hessian matrix of the MLE cost function are derived. The characteristics of the proposed joint discriminator are analyzed based on the properties of the MLE cost function,gradient vector, and Hessian matrix. The effectiveness of IMLE is verified by Monte Carlo simulation.