Rapid Communication. Exposure assessment of biomechanical stress in repetitive manual work using frequency-weighted filters

A quantitative exposure assessment strategy for physical stress associated with repetitive manual tasks is proposed using continuous biomechanical data measured directly from electrogoniometers or force sensors. This paper describes an efficient method for reducing large quantities of biomechanical data into a quantifiable metric that accounts for recognized musculoskeletal exposure factors, including repetitiveness, postural or forceful exertion stress, and duration. A frequency domain approach is used for averaging elemental data recorded for repetitive cycles. Parameters for frequency-weighted filters are developed using psychophysical data for equivalent discomfort levels resulting from repetitive movements of different amplitudes and frequencies. These filters enable continuous biomechanical data to be filtered and integrated, resulting in a single quantity corresponding to psychophysical response characteristics for repetitive motion stress. It is anticipated that a similar approach may be used for epidemiological response characteristics. Applications of this theory may make it possible for assessing exposure to physical stress in a manner analogous to the way in which sound level meters are used for measuring exposure to acoustic noise. Repetitive wrist flexion and localized discomfort was used for demonstrating the feasibility of this approach. Suitable data reduction techniques are necessary for evaluating work methods, job designs, and for conducting large scale detailed epidemiological investigations of cumulative trauma disorder risk factors. Frequency-weighted filters based on human response to physical stress at different frequencies can greatly simplify exposure analysis and ultimately may make it possible for quantitative exposure limits to be established.     

A Probabilistic Analysis of Multiple-drug Testing Procedures in Sports Doping Control

Athletes engaged in competition, particularly those involved in international competitions such as the Olympics, are increasingly being tested for a greater variety of banned substances; it is not unusual for tests to be conducted for 100 drugs and another 400 as metabolites. Previous studies related to the accuracy of drug testing processes have failed to properly consider the effects of testing for more than one drug. In order to identify appropriate indicators for the multiple-drug case, probability theory and accuracy concepts applicable to testing for multiple drugs are developed and applied to illustrative data. The probability that a drug-free individual will test positive for drug use is shown to be much higher than indicated by previous studies, and it is shown that an increase in the number of drugs tested for yields an approximately proportionate increase in the probability that a positive test result is erroneous. Therefore, while testing for one drug may result in a comfortably low rate of false accusations of drug use, testing for multiple drugs may well result in an unacceptably high rate. Finally, a set of empirical measures is suggested for use in cases of tests for multiple drugs; the measures will provide for comparability among laboratory proficiency studies.     

Characterization of reconfigurable Stewart platform for contour generation

The limited treatment available for Stewart platform characteristics leads to the lack of an efficient methodology for determining the optimum geometry for different tasks. In this paper, an effort is made to characterize the parameters for developing a reconfigurable Stewart platform for the contour generation application. A solution is provided through the formulation of dimensionless parameters in combination with a study on the generic parameters like configuration. The variable geometry approach for the reconfiguration of Stewart platform has been adopted for four different platforms, and a generic approach is formulated after studying different parameters. A stiffness model developed for contour generation application is used in tandem with this generic approach to identify the trajectory with maximum stiffness for complex contours. The proposed methodology provides a holistic approach to develop a complete set of design tool to choose the optimum geometry for any new reconfigurable Stewart platform to be developed.     

一类孤立因子阈值的计算方法

介绍一种孤立点因子的评价方法LOF,基于LOF给出一种修改的孤立因子评价标准MLOF,它不仅适用于聚类模式的孤立点发现,还适用于规则模式的孤立点发现;阐述了基于MLOF的一类孤立因子阈值的计算方法,实验表明这种方法具有良好的推荐效果.     

Joint organisational and technical development of CIM-systems: An extension of the classic scandinavian approach

In Scandinavia theories and methods for cooperative design tools for the computer supported craftsman have been the topics for intensive research for several years. This paper widens the discussion by taking in the question of CIM and the reshaping of the division of labour, work organisation and manufacturing processes. The paper argues for an evaluation of methods and tools developed for very different aspects of integrated manufacturing.     

Efficient Development of Lexical Language Resources and their Representation

Statistical approaches in speech technology, whether used for statistical language models, trees, hidden Markov models or neural networks, represent the driving forces for the creation of language resources (LR), e.g., text corpora, pronunciation and morphology lexicons, and speech databases. This paper presents a system architecture for the rapid construction of morphologic and phonetic lexicons, two of the most important written language resources for the development of ASR (automatic speech recognition) and TTS (text-to-speech) systems. The presented architecture is modular and is particularly suitable for the development of written language resources for inflectional languages. In this paper an implementation is presented for the Slovenian language. The integrated graphic user interface focuses on the morphological and phonetic aspects of language and allows experts to produce good performances during analysis. In multilingual TTS systems, many extensive external written language resources are used, especially in the text processing part. It is very important, therefore, that representation of these resources is time and space efficient. It is also very important that language resources for new languages can be easily incorporated into the system, without modifying the common algorithms developed for multiple languages. In this regard the use of large external language resources (e.g., morphology and phonetic lexicons) represent an important problem because of the required space and slow look-up time. This paper presents a method and its results for compiling large lexicons, using examples for compiling German phonetic and morphology lexicons (CISLEX), and Slovenian phonetic (SIflex) and morphology (SImlex) lexicons, into corresponding finite-state transducers (FSTs). The German lexicons consisted of about 300,000 words, SIflex consisted of about 60,000 and SImlex of about 600,000 words (where 40,000 words were used for representation using finite-state transducers). Representation of large lexicons using finite-state transducers is mainly motivated by considerations of space and time efficiency. A great reduction in size and optimal access time was achieved for all lexicons. The starting size for the German phonetic lexicon was 12.53 MB and 18.49 MB for the morphology lexicon. The starting size for the Slovenian phonetic lexicon was 1.8 MB and 1.4 MB for the morphology lexicon. The final size of the corresponding FSTs was 2.78 MB for the German phonetic lexicon, 6.33 MB for the German morphology lexicon, 253 KB for SIflex and 662 KB for the SImlex lexicon. The achieved look-up time is optimal, since it only depends on the length of the input word and not on the size of the lexicon. Integration of lexicons for new languages into the multilingual TTS system is easy when using such representations and does not require any changes in the algorithms used for such lexicons.     

Discrete estimators of characteristics for periodically correlated time series

Results of an investigation of the characteristic estimator properties for periodically correlated time series obtained on the basis of finite data length are given. The formulae for the bias and variance of the estimators for mean and covariance function Fourier coefficients are found. The conditions for the choice of sampling interval value, for which aliasing effects do not appear, are obtained. The interpolation formulae for the mean and covariance function estimates are derived. The dependencies of the statistical characteristics of the estimators on sampling interval and sample size for modulated signals are analyzed.     

选择高性能DSP构成实时控制系统

随着控制理论与策略越来越复杂,对自动控制系统提出了更高的要求,特别是对实时性要求很高的复杂控制系统,对计算机方面的要求更为苛刻。ADSP2106X在数字信号处理的各个领域得到了较多应用,而本文从其运算速度,数据动态范围,存储容量,存取速度,扩展片外各类接口能力,I/O能力,中断处理功能,程序设计优化和构成多处理器系统能力等方面详细论述了采用其构成实时控制系统的优越性,对设计复杂实时控制系统时对机型的选择具有较高的参考价值。     

Constraint Solving for Term Orderings Compatible with Abelian Semigroups, Monoids and Groups

It is crucial for the performance of ordered resolution or paramodulation-based deduction systems that they incorporate specialized techniques to work efficiently with standard algebraic theories E. Essential ingredients for this purpose are term orderings that are E-compatible, for the given E, and algorithms deciding constraint satisfiability for such orderings.Here we introduce a uniform technique providing the first such algorithms for some orderings for abelian semigroups, abelian monoids and abelian groups, which we believe will lead to reasonably efficient techniques for practice.Our algorithms are in NP, and hence optimal, since in addition we show that, for any well-founded E-compatible ordering for these E, the constraint satisfiability problem is NP-hard even for conjunctions of inequations.     

Loss rates for stochastic fluid models

We introduce loss rates, a novel class of performance measures for Markovian stochastic fluid models and discuss their applications potential. We derive analytical expressions for loss rates and describe efficient methods for their evaluation. Further, we study interesting asymptotic properties of loss rates for large size of the buffer, which are crucial for identifying the Quality of Service requirements guaranteed for each user. We illustrate the theory with a numerical example.     

Creating names for retrieval by self and others

Two experiments aimed to explore the general usability of filenames that were either chosen for personal use or designed for another user, within a document-filing scenario. Both experiments revealed a strong benefit for using self-chosen names over using names that were chosen by another for their personal use. However, both experiments also showed that participants could to some extent adapt their chosen names for use by a wider population. In experiment one, users could recall these 'designed' names more accurately than names that had been chosen for personal use by another (although this difference was not evident in a recognition test). Experiment two supported this effect; names designed for general use were more accurately recalled by another than the names designed for self-use after two sessions of use. Names designed for general use employed higher frequency words than did the self-chosen names, which supports the view that the benefit for self-chosen names partly lies in their exploitation of idiosyncratic associations.     

Database design with user-definable modelling concepts

Modelling is an integral part of engineering processes. Consequently, database design for engineering applications should take into account the modelling concepts used by engineers. On the other hand, these applications exhibit a wide diversity of modelling concepts. Rather than consolidating these into one single semantic data model one should aim for correspondingly specialized semantic models. This paper takes a constructive approach to developing such specialized models by proposing an Extensible Semantic Model (ESM) as the basis for declaring specialized semantic data models. The paper introduces a computerized environment for database design based on an ESM, and discusses the consequences of the ESM for a number of design tools: the need for a formal definition of the notion of modelling concept in order to have reliable and precise foundation for the extensions, declarative techniques for quickly introducing graphical representations for new concepts and for using them during schema design, conceptual-level test data generation for a designer-oriented evaluation of designs, and optimization techniques to control the wide latitude in mapping a conceptual schema to a logical schema. First experiences seem to point to considerable productivity gains during database design.     

Meme Media for Clipping and Combining Web Resources

The publication and reuse of intellectual resources using the Web technologies provide no support for us to clip out any portion of Web pages, to combine them together for their local reuse, nor to publish the newly composed object as a new Web page for its reuse by other people. This paper shows how the meme-media architecture is applied to the Web to provide such support for us. This makes the Web work as a shared repository not only for publishing intellectual resources, but also for their collaborative reediting. We will propose a general framework for clipping arbitrary Web contents as live objects, for defining IO ports on such a clip, and for the recombination and linkage of such clips based on both the original and some user-defined relationships among them. In our previous works, we proposed two separate frameworks for these three purposes; one works for the first two, and the other for the last. Here we will propose a unified framework for these three purposes, as well as its detailed internal mechanisms. Then we show how it can be easily applied to various legacy Web applications to develop innovative services.     

Compact disc standards: an introductory overview

The success of the compact disc (CD) as a storage medium for digital audio has, over the last ten years, resulted in a number of initiatives to use the CD for other applications as well, e.g., as read-only memory for computers, as a storage medium for audio-visual material for multimedia applications, and as a storage medium for photographs. Each of these applications poses additional requirements on how the corresponding information is stored and retrieved, resulting in a range of different CD standards. The functional specifications of these standards are each given a specific color for ease of reference: the Red Book for CD-DA, the Yellow Book for CD-ROM, the Green Book for CD-I, etc. This paper aims at giving an overview of the various CD standards by explaining what is specified in each of the colored books and by indicating how they relate to one another.     

Mouse Selection Versus Voice Selection of Menu Items

Subjects completed a menu selection task using mouse and spoken language technologies for menu sizes that are powers of 2 from 2 to 256. It was found that mouse selection was faster than spoken language selection for menu sizes of 32 or less for most subjects. For small N, mouse selection was about three times faster. Spoken language selection was as fast or faster for menus of size 64 or larger. The trade-off size, approximately 64, was different for various subjects, but not greatly different. Data was gathered for words with one, two, and three syllables with the result that the trade-off size was the same for all three, but the error characteristics for spoken inputs were worse for shorter words, as would be expected.     

证书和私钥漫游系统的设计方案

阐述了PKI应用系统中数字证书和私钥漫游的必要性和可行性，给出了数字证书和私钥漫游系统的设计方案。该方案提出了证书和私钥漫游系统的两种运行模式：作为独立的系统运行，可以为多个CA颁发的证书和私钥提供漫游服务；与CA认证系统结合在一起，只对本CA所颁发的证书和私钥提供漫游服务。方案详细描述了用户注册、证书和私钥的上传、下载流程以及安全方面的设计。     

水利系统干部人事档案数字信息化建设探索与实践

干部档案数字信息化建设是干部档案工作在信息化时代的必由之路,是提高干部信息管理和利用水平的必然要求。在阐述档案数字信息化概念的基础上,以南京水利科学研究院干部人事档案数字信息化建设为实例,对水利干部人事档案数字信息化建设进行有益探索,提出水利系统干部人事档案数字信息化系统建设的要素确定、基本程序及主要环节,具有实用性和可操作性。     

Stability of difference Volterra equations: Direct Liapunov method and numerical procedure

A procedure to construct Liapunov functionals for discrete Volterra equations is proposed. Using this procedure stability conditions are derived for general Volterra difference equations. Some applications of the proposed procedure for obtaining stability conditions for linear multistep methods for Volterra integro-differential equations are presented.     

Estimating the Attraction Domain for the Boost Inverter

This work presents an approach for estimating the domain of attraction for polynomial systems with state and control‐signal constraints, including saturation. In many problems, it is possible to derive global stability properties for such systems, neglecting constraints. Consideration of the constraints usually makes the problem much more complicated. In this paper, the stability analysis performed for the unconstrained case is used for the problem as a whole. For application of the method, there are powerful computational tools that can be employed in cases of polynomial systems. The technique is not only valid for the analysis of equilibrium points, but also for other attractors, such as limit cycles. As examples, the domain of attraction for given control laws is estimated for both a nonlinear DC‐DC boost converter and for a boost inverter.     

一种分布动态网络安全系统框架

网络是人类社会全新的活动空间。这个活动空间必须符合人类社会活动的规则。信息安全是其中最重要的问题。安全问题不是某个使用网络部门的事,而是需要全社会合力解决的问题。本文从入侵检测信息的标准化入手,提出了一个分布动态网络安全系统框架结构。探讨了分布动态网络安全系统框架的层次结构、通讯方式和协议,通过分布动态网络安全系统框架解决攻击源定位、攻击响应及重要应用系统的防护等问题。