A formal description of open distributed processing (ODP) trading based on guidelines for the definition of managed objects (GDMO)

New requirements of growing computer networks and information systems have an influence on extended client/server models with increased functionality. This forms the basis for service management in distributed systems which is realized by a service trading concept. This paper studies the requirements derived from the Open Distributed Processing (ODP) Reference Model in order to consider an open service market. Furthermore, it examines management possibilities for describing the service trading scenario. Because of similar architectures and properties ODP services, service offers, types, exporters and traders are mapped onto management components and modeled as managed objects. Therefore, the Guidelines for the Definition of Managed Objects (GDMO) are used. The final concept allows a precise and unambiguous study of the service trading scenario and provides means for exporting and importing of service offers in a distributed environment.     

The Art of the Accessibility Statement

ABSTRACT

Many libraries recognize the need to create Web sites accessible to users with disabilities, as legislated in U.S. Code Section 508, but Section 508 compliance defines a minimum legal level of accessibility. The same technology that can make a Web site available to users with disabilities can also make the site available to users with wireless devices, such as PDAs and cell phones, with Internet access. To bring about “maximum accessibility,” library Web designers need to implement Web standards. This article argues the place to begin implementing these standards is with an accessibility statement which serves as both a contract and a navigational aid.     

Guidelines for energetic load in three methods of refuse collecting

The energetic load and guidelines were formulated for energetic load in three methods of refuse collecting. These methods were collecting refuse in polythene bags (in a city area and in a suburb), in two-wheeled mini-containers and in large four-wheeled containers. To determine the energetic load of the collecting methods, these collecting methods were simulated in the laboratory. The simulation protocols were based on data such as weight of the handled materials, and the frequency and duration of the most prominent refuse collecting activities as found in the preliminary field study. During the execution of the protocols the heart rate and oxygen uptake were continuously recorded. The maximal oxygen uptake was determined during a continuous running protocol on a treadmill. The energetic load was expressed in terms of percentage of the maximal oxygen uptake. As the limit for the energetic load a value of 30% of the maximal oxygen uptake during an 8-h working day was chosen. The limit for energetic overload was exceeded for the maximal oxygen uptake for refuse collecting with polythene bags in a city area (44·5%), collecting with bags in a suburb (37·2%) and with mini-containers. The percentage of the maximal oxygen uptake for collecting with large containers was 28·4%, which was below the limit for the energetic load of 30%. Guidelines were formulated for the relevant occupational field terms: maximal amount of collecting hours and maximal amount of collected refuse per collector per hour. The guidelines were formulated in percentiles (P₉₀ and P₇₅). This means that 90 and 75% of the refuse collecting population in The Netherlands will be prevented from having an energetic overload above the limit of 30% of the maximal oxygen uptake.     

Toward methods for supporting the anticipation-feedback loop in user interface design

Recent research has compared different usability evaluation methods with respect to their effectiveness and efficiency. The paper analyses the impact of different usability evaluation methods on design problem-solving processes of individual designers and evaluators. It is proposed that usability evaluation methods have to be divided into two categories according to their fundamentally different way of supporting the design for usability: (1) guideline-based methods and (2) methods based on the mental generation of scenarios and anticipation of user goals. We present data from an experimental study that shows that these two types of methods entail differences in the perspective-taking processes. Furthermore, the results indicate that the methods have a differential impact on the general problem-solving strategy, i.e. whether to use a top-down, breadth-first or a depth-first approach. Possible implications for the development of techniques that support the design of usable systems are discussed.     

Using a circadian rhythms model to evaluate shift schedules

As long as the need for shiftwork exists, so will the demand for an optimal scheduling strategy that balances the needs of both industry and the shiftworker. One aim is for schedules that require workers to be on duty during the times that they are most naturally alert and awake. Czeisler et al. (1982) developed a set of circadian rhythm based guidelines intended to aid in designing such shiftwork schedules. This paper takes research one step further by testing such empirical criteria in a mathematical setting. The two-oscillator model of free-run human circadian rhythms developed by Kronauer et al. (1982) was modified to represent the circadian rhythms of a shiftworker on a pre-selected shiftwork schedule. Numerical simulations were used to compare the circadian rhythms produced from a variety of shiftwork schedules to the free-run rhythms. Shift schedules that resulted in circadian rhythms closest to the free-run rhythms were identified as preferred schedules. The numerical results supported Czeisler's findings (1982), indicating the best shift schedules adopt a slow, forward-shifting rotation pattern, rotate shifts after 2-week periods and allow an average of 2 days o^ff per week.     

Guidelines for shiftworkers: trials and errors?

86 guidelines for shiftworkers were assembled by a team of European experts and published as the Bulletin of Shiftwork Topics No. 3. Before publication, 24 of the personally directed guidelines were tested against the normal actions of two groups of mixed sex industrial 3-shift continuous workers (n = 120). Six of the guidelines were endorsed as their practice by a majority of both groups; six were opposed by a majority of both groups; and twelve were intermediate. The six that were opposed are closely examined. Half of them fall into specific remedies for sleep problems, that were more abruptly phrased in the questionnaire than in the guidelines. The other three are concerned with eating and drinking: breaking your sleep to join in a family meal is only a gentle suggestion in the guidelines, and not a sensible general recommendation for day-sleepers; avoiding fatty foods may only be appropriate if you have digestive problems; and avoiding coffee and tea in the last two hours before sleep appears to oppose and lose out to work and home pressures. An evaluated intervention is required to check these points.     

Increasing usability when interacting through screen readers

The application of appropriate Web site design and evaluation methods helps to ensure more usable and accessible Web sites. While in the literature guidelines and evaluation methods for accessibility and usability are given and discussed separately, we aim at identifying the relationships between these two concepts, in particular considering usability criteria for accessible Web sites. In this work, we propose a set of such criteria targeted to improving the navigability for a specific group of disabled users, i.e., vision-impaired people. The identification of the eighteen criteria suggested herein was performed through empirical feedback, by which potential issues were identified. Subsequently, a systematic method was developed on the basis of the analysis of potential solutions, resulting in a classification of the criteria according to usability aspects. Some example applications of the proposed criteria to three existing public administration Web sites are discussed.     

Siting guidelines for concentrating solar power plants in the Sahel: Case study of Burkina Faso

Selecting a site that meets the technical requirements for a concentrating solar power plant (CSP) is a very critical exercise. This paper points out crucial factors and provides guidelines regarding the selection of suitable sites. It especially focuses on Sahelian countries which have their own climatic peculiarities. These countries, characterized by low access to electricity, are well endowed in solar resources. They are potentially good locations for concentrating solar power plants since their mean daily solar radiation exceeds 5.5 kWh/m². CSP presents therefore, a good opportunity for them to increase in a sustainable manner, their energy supply. The guidelines developed in this paper are applied to Burkina Faso as a case study.     

Refinery-wide control loop performance assessment

This paper discusses the application of control loop performance assessment (CLPA) in a refinery setting. The CLPA algorithm has several parameters that have to be adjusted correctly to give the best results. Procedures are described for selecting these parameters which make it feasible to implement the algorithm on a refinery-wide scale. We report practical experiences with the use of the techniques.     

High-resolution wind-driven rain measurements on a low-rise building—experimental data for model development and model validation

With the specific intention to provide experimental data for model development and model validation, a new measurement setup for wind, rain and wind-driven rain (WDR) has been designed and installed at the Laboratory of Building Physics (Katholieke Universiteit Leuven). This paper focuses on the new measurement setup and on the obtained measurement results. The CFD-based design and the installation of the measurement setup are outlined and samples of the database containing the wind, rain and high-resolution WDR measurements are provided and discussed. This paper also provides the link to a website from which the experimental WDR database can be downloaded. Finally, the use of these data to determine WDR coefficients and their use in WDR assessment are briefly addressed.