Note To The Mixed-Type Splitting Iterative Method For The Positive Real Linear System

In [5] a new iterative method is given for the linear system of equations Au=b , where A is large, sparse and nonsymmetrical and A^{\rm T}+A is symmetric and positive definite (SPD) or equivalently A is positive real. The new iterative method is based on a mixed-type splitting of the matrix A and is called the mixed-type splitting iterative method. The iterative method contains an auxiliary matrix D_1 that is restricted to be symmetric. In this note, the auxiliary matrix is allowed to be more general and it is shown that by proper choice of D 1 , the new iterative method is still convergent. It is also shown that by special choice of D_{1} , the new iterative method becomes the well-known (point) accelerated overrelaxation (AOR) [1] method. Hence, it is shown that the (point) AOR method applied to the positive real system is convergent under the proper choice of the overrelaxation parameters y and .     

A case study in the mechanical verification of fault tolerance

To date, there is little evidence that modular reasoning about fault-tolerant systems can simplify the verification process in practice. This question is studied using a prominent example from the fault tolerance literature: the problem of reliable broadcast in point-to-point networks subject to crash failures of processes. The experiences from this case study show how modular specification techniques and rigorous proof re-use can indeed help in such undertakings.     

Further studies of shoulder and neck pain and exposures in customer service work with low biomechanical demands

The aim of the study was to establish insight into work exposures that cause shoulder and neck pain among occupational groups that have low biomechanical exposure and experience work stress from client/customer contact, among other exposures. Four occupational groups were studied, in health care (n = 20), retail (n = 22), banking (n = 26), and university secretaries (n = 26), a total of 94 volunteers. Thirty-nine were classified as pain-afflicted in the shoulder and neck, while 55 were pain-free. The subjects' perceptions of biomechanical and psychosocial exposures were established by use of quantitative questionnaires and by explorative interviews with open-ended questions, covering the same themes. Heart rate and trapezius EMG were recorded over a full workday and the following leisure period. Trapezius median and static activity during work were 3.3% and 0.3% EMG_max, only marginally higher than trapezius activity in the leisure period (2.7% and 0.2% EMG_max). The quantitative questionnaire did not identify any variable that correlated with shoulder and neck pain except perceived general tension. The interviews established that the interaction with clients or customers was an important source of work stress. Such stress appeared to be a complex entity not easily characterized by established psychosocial questionnaires. The physiological variables were at most weakly elevated in periods with high stress as compared to periods with low stress. The authors caution against relying on standardized quantitative questionnaires and/or physiological recordings to characterize work stress in occupations with emotional stress through client/customer service work.     

Normal horizontal working area: the concept of inner boundary

A model was developed to determine the inner boundary of the normal horizontal working area based on the concept that the elbow and forearm-hand should move on the table surface while describing the area. The proposed model was applied to determine the normal horizontal working areas for the 5th percentile female and 95th percentile male. It was shown that the conventional models that had disregarded the concept of the inner boundary overestimated the area on the average by 26%. The proposed model is more realistic and accurate than the conventional models.     

Measurement of Bulk Mechanical Properties and Modeling the Load-Response of Rootzone Sands. Part 1: Round and Angular Monosize and Binary Mixtures

The bulk mechanical properties of two different types of rootzone sands (round and angular) were measured using a cubical triaxial tester. Two monosize sands (d 50 = 0.375 mm and 0.675 mm) and their 50:50 binary mixtures (d 50 = 0.500 mm) were studied. The compression, shear, and failure responses of the above-mentioned six compositions were analyzed, compared, and modeled. Two elastic parameters (bulk and shear moduli) and two elastoplastic parameters (swelling and consolidation indices) of the six sand compositions were also calculated and compared. The angular sand was more compressible than round sand during isotropic compression. In addition, the angular sands tended to have lower initial bulk density and high porosity values. Among the three different size fractions, the 0.375 mm mixture was least compressible for both sand shapes. The failure strength and shear modulus of the angular sand were higher than the round sands. In addition, due to their simplicity, phenomenological models were developed to predict the compression and shear behavior of the sands. The prediction models were validated using subangular and subround sands. Average relative difference values were calculated to determine the effectiveness of the prediction models. The mean average relative difference values for compression profiles, i.e., volumetric stress vs. volumetric strain, were from 16 % to 39 %, except for the initial load-response portion (< 1 % volumetric strain). The predictive models were effective in reproducing the failure responses: at 17.2 kPa confining pressure, the mean of average relative difference was 23 %; at 34.5 kPa , the mean difference was 24 %.     

现代港口与城市发展的关系——以江苏省镇江市为例

镇江是一座历史文化名城，素有“天下第一江山”之美誉，它的形成发展与其港口是密不可分的。本文从镇江港口空间形态、城市空间形态、港口与城市发展的关系为切入点，寻求港城空间发展对策。     

居住小区规划设计课程教学方法研究

本文介绍了大连理工大学居住小区规划设计课程提高教学质量的具体措施,通过改进设计地块给定方式,安排学生实地调研居住片区和优秀住区,体验居住生活,整合院校教学资源,增加户型选型、景观设计、技术设计、工程设计等方面专题讲座,加强教学管理,检查阶段设计成果等多种教学方法,实现全面提高学生居住小区规划设计水平的教学目标。     

浅谈环境认证和电线电缆的发展

文章主要介绍了电线电缆的环境认证标准及绿色电线电缆的发展及应用。     

Wild Ways and Paths of Pleasure: Access to British waterfalls, 1500–2000

In Britain the rise of tourism, largely associated with the Romantic taste for landscape, encouraged travel to relatively inaccessible areas. Among travellers in search of the picturesque and the sublime, waterfalls were particularly popular, but these were commonly difficult and dangerous places to visit. The impact of tourism on the evolution of the landscape at waterfall sites over a period during which people travelled to tourist centres on horseback, by coach, by rail and by motor vehicle is examined. Drawing on topographical, travel and tourist literature from the sixteenth century to 2000, together with extensive field observation, the evolution from the 'natural' to the designed landscape, created to meet the needs of, and to attract, visitors, is considered. It is demonstrated how, while facilitating visits to natural attractions such as waterfalls, improved access and the provision of amenities have changed valued landscapes and, hence, the visitor's experience of them.     

Intra-team boundaries as inhibitors of performance improvement in UK design and build projects: a call for change

The success of the design and build (D&B) procurement route could be undermined by issues arising from the rigid professional cultures of individual participants within project workgroups. These have the potential to inhibit the achievement of a key espoused benefit of D&B procurement, i.e. that it promotes the integration of the design and construction processes for improved project performance. Cultural non-interoperability is identified as a significant potential barrier to effective change management, and to the achievement of innovation within the design and construction processes. This note argues that project responsibilities, which currently are delineated along professional identity lines, produce design and construction solutions that fail to fulfil the potential of D&B procurement. It is suggested that addressing cultural interoperability will require a fundamental and long term reshaping of the industry's structure, beginning with the professional bodies and the higher education system that underpins their future membership.