SAS and SPLUS programs to perform Cox regression without convergence problems

When analyzing survival data, the parameter estimates and consequently the relative risk estimates of a Cox model sometimes do not converge to finite values. This phenomenon is due to special conditions in a data set and is known as 'monotone likelihood'. Statistical software packages for Cox regression using the maximum likelihood method cannot appropriately deal with this problem. A new procedure to solve the problem has been proposed by G. Heinze, M. Schemper, A solution to the problem of monotone likelihood in Cox regression, Biometrics 57 (2001). It has been shown that unlike the standard maximum likelihood method, this method always leads to finite parameter estimates. We developed a SAS macro and an SPLUS library to make this method available from within one of these widely used statistical software packages. Our programs are also capable of performing interval estimation based on profile penalized log likelihood (PPL) and of plotting the PPL function as was suggested by G. Heinze, M. Schemper, A solution to the problem of monotone likelihood in Cox regression, Biometrics 57 (2001).     

Translation and execution of distributed Ada programs: Is it stillAda?

Some of the fundamental issues and tradeoffs involved in the translation and execution of programs written in the Ada language and intended for distributed execution are examined. The memory access architecture, binding time and degree of system homogeneity are the three basic characteristics in terms of which target systems can be described. Library subprograms and library packages are identified as natural distributable units of the language. The program-to-process/memory mapping and the unit of the language to be distributed are the key issues in the distribution of Ada. The implications of various alternatives for these are analyzed     

Multi-attribute Group Decision-making Based on Hesitant Bipolar-valued Fuzzy Information and Social Network

Fuzzy sets have undergone several expansions and generalisations in the literature, including Atanasov’s intuitionistic fuzzy sets, type 2 fuzzy sets, and fuzzy multisets, to name a few. They can be regarded as fuzzy multisets from a formal standpoint; nevertheless, their interpretation differs from the two other approaches to fuzzy multisets that are currently available. Hesitating fuzzy sets (HFS) are very useful if consultants have hesitation in dealing with group decision-making problems between several possible memberships. However, these possible memberships can be not only crisp values in [0,1], but also interval values during a practical evaluation process. Hesitant bipolar valued fuzzy set (HBVFS) is a generalization of HFS. This paper aims to introduce a general framework of multi-attribute group decision-making using social network. We propose two types of decision-making processes: Type-1 decision-making process and Type-2 decision-making process. In the Type-1 decision-making process, the experts’ original opinion is proces for the final ranking of alternatives. In Type-2 decision making processs, there are two major aspects we consider. First, consistency tests and checking of consensus models are given for detecting that the judgments are logically rational. Otherwise, the framework demands (partial) decision-makers to review their assessments. Second, the coherence and consensus of several HBVFSs are established for final ranking of alternatives. The proposed framework is clarified by an example of software packages selection of a university.     

Symbolic modeling in robotics: Genesis,applicaton, and future prospects

This survey article gives an overview of software packages for generating numerically efficient manipulator models in symbolic form, i.e. as computer programs written in a high-level language such as C or FORTRAN. We chronicle the history of computational robot dynamics and, to some extent, multibody systems dynamics. We survey several mechanical computer-aided engineering software packages because they have charted the course for symbolic robot modeling software. The attractive features of various programs regarding areas of application (vehicles, robots, satellites, etc.) and design possibilities (kinematic and dynamic analysis, modal analysis, optimization of mechanical design, numerical efficiency of generated symbolic models, etc.) are emphasized. Finally, as an example, we present the SYM program package in more detail and point out the new strategic area of robotics which has emerged during the last two years: computer-aided generation of control laws.     

Estimation in mixed models via layer triangular transformation

A new alternative for estimating parameters in some mixed linear models is presented and illustrated. The approach is based on the same layer triangular transformation of the model matrix as proposed earlier by Öfversten (Biometrics 49 (1993)) for the derivation of some exact tests for variance components. Using the same preliminary transformation for both testing and estimation gives us an integrated set of procedures for the full analysis of some widely used mixed linear models. The proposed procedures are computationally stable and space saving.     

基于电力载波的电能质量监测系统

电能质量已经引起了国家和众多方面的密切关注,建立电能质量监测及分析系统,对电能质量进行正确地检测、评估和分类,了解电网长期负荷状态和污染程度,是提高电能质量的必要手段。本文设计了基于电力线载波的电能质量监测系统,对系统硬件设计、软件实现及系统实现的功能进行了详细介绍。     

Analysis of fading statistics in cellular mobile communication systems

Spatial channel models are often proposed for modeling the angular aspects of mobile radio channel in picocell, microcell, and macrocellular environments. These models are validated through comparison with available measurement results. The comparisons are usually based on the fitness of their pdfs of angle of arrival to the histogram of occurrences of the signals over an angular span, given in the measurement data. This paper presents a comparison of the notable scattering models with various spatial channel measurements. The paper suggests criteria for the comparative analysis of the previously proposed spatial channel models and measurements on the basis of their fading statistics. Quantitative analysis of the considered models and the field measurements is also presented using multipath shape factors i.e. angle spread, the angular constriction and direction of maximum fading. Based on the obtained shape factors, fading statistics like level crossing rates, average fade duration, auto-covariance and coherence distance are evaluated. Effect of increasing Doppler spread on the level crossing rates and average fade duration is also elaborated in detail.     

CAD model repair using knowledge-guided NURBS

This paper presents a methodology to repair flawed migrated models that are designed with knowledge-guided NURBS (KGN). Incompatible traditional CAD packages that are based on NURBS technology have been for many years carrying out the exchange of models and data through either neutral file formats (IGES or STEP) or proprietary formats. The exchange process most often produces poor quality data and results in errors in the migrated CAD models costing the industry billions of dollars every year. While previous studies by large focus on finding means to repair migrated models through patching, we propose to repair errors in CAD models which are generated using KGN through a reconstructing process instead of patching. We have implemented a prototype system to show that employing the right tools on the stored knowledge and data a designer can reconstruct a migrated model based on new local requirements of the receiving system without having to repair it, avoiding delay and corrective processes that only produce patched-up design bases and limiting the effective use of such models.     

A configurable reference modelling language

Enterprise Systems (ES) are comprehensive off-the-shelf packages that have to be configured to suit the requirements of an organization. Most ES solutions provide reference models that describe the functionality and structure of the system. However, these models do not capture the potential configuration alternatives. This paper discusses the shortcomings of current reference modelling languages using Event-Driven Process Chains (EPCs) as an example. We propose Configurable EPCs (C-EPCs) as an extended reference modelling language which allows capturing the core configuration patterns. A formalization of this language as well as examples for typical configurations are provided. A program of further research including the identification of a comprehensive list of configuration patterns, deriving possible notations for reference model configurations and testing the quality of these proposed extensions in experiments and focus groups is presented.     

DSLAM技术模式的监听网关设计分析

由于ADSL（Asymmetric Digital Subscriber Line）端到端的通讯结构,传统的监听技术很难进行,在分析了ADSL数据承载方式和用户认证的基础上,设计了一种基于DSLAM（Digital Subscribe Loop Access Multiplexer）技术模式的监听网关。详细描述了IP数据的获取以及ATM通道的映射,实现了对ADSL用户网络层数据的在线监听。     

An integrated approach for the configuration of automated manufacturing systems

The paper proposes a new integrated approach for supporting firms in their decisions of dimensioning automated production systems. The problem is closely related to the performance evaluation of the system since discriminating indicators are necessary to rank different alternatives. Traditionally, analytical methods and simulation have been used to evaluate the production system performance, with minor emphasis on the relationships between the tools and their use. Given the complexity of the problem, it is not possible to use only analytical methods that cannot enter deeply in problem details; at the same time the space of potential system configurations is too large to be evaluated by means of detailed tools such as simulation. In the proposed methodology, the problem is decomposed hierarchically into different sub-problems; each one has a different level of detail and a specific performance evaluation tool is used. At each level of the analysis, each system configuration is compared, by means of statistical tests, with the other alternatives with the purpose of discarding unprofitable solutions.     

软件安全性研究综述

软件是安全性关键的软件密集型系统(比如综合航电系统)的一个重要安全因子,软件安全性已逐渐成为软件工程和安全工程交又领域的研究热点之一。对软件安全性的内涵与外延进行了剖析,给出了软件安全性定义。讨论了软件安全性的度量模型。着重从软件工程的视角对软件安全性的开发过程、设计方案、评估方法与认证技术等现状进行了综述,并探讨了软件安全性的研究方向。     

基于神经网络的失效树算法选择

失效树分析广泛应用于工业系统的可靠性分析。有几种算法可以实现。尽管这种分析使用广泛，但是当处理大型失效树结构时就会显示出在精确性和有效性方面的局限性。本文着眼于通过神经网络从一系列算法选项中选择一个最佳算法。经过神经网络的两次筛选，对于任意失效树，其选择最佳算法的预测能力是90％。     

基于音频指纹的两步固定音频检索

提出了一种基于过零率和音频指纹的两步固定音频检索算法.在基于过零率直方图的初步检索中,采用直方图的迭代计算和动态的观测窗滑动步长来减少计算量并加快搜索速度,快速筛选出相似度较高的候选音频片段;接着基于降维Philips音频指纹对候选音频进行精检索,进一步提高检索精度.实验结果表明,该音频检索算法在保证较好的检索准确性基础上,大幅度提高了检索速度,且具有较好的鲁棒性.     

A method for the production of simulation models with application to web interaction paradigms

Modern internet and web applications rely on interactions among remote host computers connected by heterogeneous networks (different LANs, gateways, WANs, MANs, etc.). Simulation modelling such networks is of great importance to the web application designer to predict, at design time, performance metrics such as the end-to-end delay between hosts, which is dramatically increased by the various mechanisms necessary to deal with heterogeneity (protocol conversion, packet fragmentation and re-assembly, flow control, etc.).On the other hand, producing a simulation model of web interactions is a non-trivial task because of the great importance of the software aspects. It is thus necessary to provide general model production guidelines which can be then tailored and applied to specific simulation languages or packages.This paper gives such general production guidelines with an example application to the production of simulation models for web interaction paradigms of client–server and mobile agent types. An example use of the models is also introduced to predict the most convenient paradigm and the best choice of the host capacities for each given network configuration.     

Novel intuitionistic fuzzy decision making models in the framework of decision field theory

The intuitionistic fuzzy decision making problems have gained great popularity recently. Most of the current methods depend on various aggregation operators that provide collective intuitionistic fuzzy values of alternatives to be ranked. Such collective information only depicts the overall characteristics of the alternatives but ignores the detailed contrasts among them. Most important of all, the current decision making procedure is not in accordance with the way that the decision makers (DMs) think about the decision making problems. In this paper, we develop a novel intuitionistic fuzzy decision making model in the framework of decision field theory. The decision making model emphasizes the contrasts among alternatives with respect to each attribute that competes and influences each other, and thus, the preferences for alternatives can dynamically evolve and provide the final optimal result. After that, we develop an intuitionistic fuzzy group decision making model based on decision field theory, and then make a practical case study on the application of the developed models to the “one belt, one road” investment decision making problems. Finally, we point out the characteristics and the limitations of our models in detail.     

Interactive computer programs for education and research: A survey

In this paper, a survey is given of the development and use of interactive computer packages for education and research in the field of control engineering, signal analysis and parameter estimation. Relevant aspects are: aims and goals of the package, its design and structure, the interaction, the development of the software, the necessary hardware, the educational aspects, the contents of the package and possible future developments.     

Diagnostics for skew-normal nonlinear regression models with AR(1) errors

In this article, we consider some diagnostics for skew-normal nonlinear regression models with AR(1) errors which provide a useful extension of the normal regression models. The estimation of the parameters in the models is studied based on the EM algorithm. Meanwhile, several score tests are presented for testing the homogeneity of the scale parameter and/or significance of autocorrelation in skew-normal nonlinear regression models. The properties of score tests are investigated through Monte Carlo simulations. The test methods are illustrated with two numerical examples.     

Bootstrap hypothesis testing for some common statistical problems: A critical evaluation of size and power properties

The construction of bootstrap hypothesis tests can differ from that of bootstrap confidence intervals because of the need to generate the bootstrap distribution of test statistics under a specific null hypothesis. Similarly, bootstrap power calculations rely on resampling being carried out under specific alternatives. We describe and develop null and alternative resampling schemes for common scenarios, constructing bootstrap tests for the correlation coefficient, variance, and regression/ANOVA models. Bootstrap power calculations for these scenarios are described. In some cases, null-resampling bootstrap tests are equivalent to tests based on appropriately constructed bootstrap confidence intervals. In other cases, particularly those for which simple percentile-method bootstrap intervals are in routine use such as the correlation coefficient, null-resampling tests differ from interval-based tests. We critically assess the performance of bootstrap tests, examining size and power properties of the tests numerically using both real and simulated data. Where they differ from tests based on bootstrap confidence intervals, null-resampling tests have reasonable size properties, outperforming tests based on bootstrapping without regard to the null hypothesis. The bootstrap tests also have reasonable power properties.     

Bootstrap hypothesis testing for some common statistical problems: A critical evaluation of size and power properties

The construction of bootstrap hypothesis tests can differ from that of bootstrap confidence intervals because of the need to generate the bootstrap distribution of test statistics under a specific null hypothesis. Similarly, bootstrap power calculations rely on resampling being carried out under specific alternatives. We describe and develop null and alternative resampling schemes for common scenarios, constructing bootstrap tests for the correlation coefficient, variance, and regression/ANOVA models. Bootstrap power calculations for these scenarios are described. In some cases, null-resampling bootstrap tests are equivalent to tests based on appropriately constructed bootstrap confidence intervals. In other cases, particularly those for which simple percentile-method bootstrap intervals are in routine use such as the correlation coefficient, null-resampling tests differ from interval-based tests. We critically assess the performance of bootstrap tests, examining size and power properties of the tests numerically using both real and simulated data. Where they differ from tests based on bootstrap confidence intervals, null-resampling tests have reasonable size properties, outperforming tests based on bootstrapping without regard to the null hypothesis. The bootstrap tests also have reasonable power properties.