Simulating a field case of reactive chloroethene transport

In this paper, the simulation of a bio-chemical in situ remediation approach is discussed. We consider a field case of a contaminant plume consisting of dissolved chloroethenes. A regional flow model shows, that the contaminants may reach a water works located 2 km downstream of the spill area. Thus, an in situ remediation is anticipated, where the dechlorination and mineralization of the chloroethenes is stimulated by a sequence of aerobic and anaerobic treatments. The equations of the reactive transport model are discretized using implicit time schemes and locally refined meshes. The resulting discrete equations are solved simultaneously with a Newton method and a point-block multigrid method, which turned out to be an efficient solver for the considered systems. Simulation results for several remediation configurations show a fast bio-chemical degradation of the chloroethenes which is, however, limited to the vicinity of the injection wells. This effect is caused by the fast decomposition of the easily degradable substrate infiltrated during the anaerobic treatment phase. The simulations suggest that the preliminary concept of the remediation scheme could be optimized, e.g. by re-injection, with respect to the in situ biodegradation efficiency. Received: 24 May 2000 / Accepted: 29 July 2001 Communicated by R. Helmig     

Design and protection of an information network under a partial ordering: A case study

In this paper, we discuss a practical information system using a partial ordering for protecting information from illicit dissemination and modification. We use an office automation system designed to assist in the operation and management of a law office as an example. We briefly review recent results in the use of partial orderings for protection and administration of information networks, describe the design process wherein a partial ordering is used to represent the structure of information and its use in a law office, and show how this particular system was designed and used. We show examples of how the partial ordering was used to simplify risk analysis and guide well informed administrative decision making. We consider the practicality of this implementation, and the effects of security and integrity protection on the performance of the office. We summarize results and point out possible extensions of this work.     

Simulating the urban spatial structure with spatial interaction: A case study of urban polycentricity under different scenarios

Polycentric urban development is gaining momentum in both scholarly research and real-life practice. This brings new demand for planning support systems to simulate and analyse the urban spatial structure in terms of polycentricity under various urban policy scenarios. With the help of emerging urban data, urban simulation techniques, and network science, this study proposes a workflow to simulate the urban spatial structure with spatial interaction as a part of the planning support system. Using Singapore as a case study, this study has explored the resulting urban spatial structure with four employment distribution strategies. The results suggest that planning practices impact urban spatial structure and its spatial interaction by redistributing urban morphological elements, such as employment in this study. Also, our results show that the physical urban spatial structure and spatial interaction are closely related. These results reinforce the role of urban planning practice to achieve a more sustainable and coherent urban built environment. Through this empirical evidence, our workflow exemplifies the potential of the planning support system to help urban planners and governments understand their urban policy regarding urban polycentricity.     

Simulating asynchronous hardware on multiprocessor platforms: the case of AMULET1

Synchronous VLSI design is approaching a critical point, with clock distribution becoming an increasingly costly and complicated issue and power consumption rapidly emerging as a major concern. Hence, recently, there has been a resurgence of interest in asynchronous digital design techniques which promise to liberate digital design from the inherent problems of synchronous systems. This activity has revealed a need for modelling and simulation techniques suitable for the asynchronous design style. The concurrent process algebra communicating sequential processes (CSP) and its executable counterpart, occam, are increasingly advocated as particularly suitable for this purpose. This paper focuses on issues related to the execution of CSP/occam models of asynchronous hardware on multiprocessor machines, including I/O, monitoring and debugging, partition, mapping and load balancing. These issues are addressed in the context of occarm, an occam simulation model of the AMULET1 asynchronous microprocessor; however, the solutions devised are more general and may be applied to other systems too. Copyright © 2001 John Wiley & Sons, Ltd.     

Robustness analysis: a case study

The stability test of polynomials whose coefficients depend multilinearly on interval parameters is considered. The authors describe and compare four brute-force solution approaches. These are eigenvalue calculation, zero exclusion from a specified value set, algebraic tests of real and complex Hurwitz roots, and the parameter space method. They are applied to a simple example with two parameters and third-order polynomial. An interesting feature of the example is that it can have an isolated unstable point. The example may be useful as a benchmark for future approaches to the multilinear problem. All four methods are shown to be feasible for the simple example, but they require effort     

Brick handling: a case study

A small change in brick dimensions resulted in an increase in the perceived work-load of men loading and unloading pallets of bricks by hand. A laboratory study indicated that the change in brick dimensions required changes in grip pattern in order to unload bricks at the same rate, moving the same number at a time. These changed grip patterns resulted in increased upper body movement, increased chest-muscle activity and higher heart rates. These differences were reflected in higher subjective ratings of fatigue.     

Structural redocumentation: a case study

Most software documentation typically describes the program at the algorithm and data-structure level. For large legacy systems, understanding the system's architecture is more important. The authors propose a method of reverse engineering through redocumentation that promises to extend the useful life of large systems     

Courseware validation: a case study

Abstract This paper discusses methods used and problems faced in the validation study of LOGICLANDIA , a courseware package for the learning and teaching of predicate logic in Italian upper secondary schools. The courseware underwent a medium scale evaluation process that involved about three hundred students. LOGICLANDIA's validation consisted of three main phases: subjective evaluation, in-house evaluation and field test. The study produced a number of indications of revision of the courseware material, as well as information about effectiveness of the educational approach and satisfaction of students. But rather than going into the details of the results of LOGICLANDIA's evaluation, the paper focuses on problems encountered and adopted solutions that can be generalised to similar cases.     

Information technology and the accountant: a case study

The factors leading to the success or failure of IT implementations by accountants are investigated in a health service situation. Tbe case study adopts the participant observation methodology and the factors observed are classified as motivators and demotivators. Using a project dependent definition of success, a catastrophe theory framework is used to describe the outcome of the combined influence of these factors. Four particular IT projects are discussed and the factors observed include: the influence of higher levels in the organizational hierarchy, some systems characteristics, the seduction of technology, external pressures, the 'rate of change', skills shortage and reliability. By comparing the examples described with features mentioned by other authors, it is noted that some factors appear to be generally applicable, whereas others may be context dependent.     

Using the WinWin spiral model: a case study

Fifteen teams used the WinWin spiral model to prototype, plan, specify, and build multimedia applications for USC's Integrated Library System. The authors report lessons learned from this case study and how they extended the model's utility and cost-effectiveness in a second round of projects     

Job-shop development model: a case study

Traditional effort-estimation models can be frustrating, especially when staff are divided among multiple projects. The authors evaluate a model based on dividing activities into jobs. It accounts for divided time and more accurately categorizes rework costs. The model lets organizations represent software development in more detail than they can with many existing models. By breaking each project into batches and each batch into jobs, the model recognizes that, at any point in time, parts of the software may be at different stages of completion     

Designing for flexibility: a case study

Abstract: Expert systems have traditionally been designed with one particular purpose in mind, whether problem-solving, critiquing etc. When the system is intended for users with varying background knowledge it becomes necessary to provide different facilities for different groups of users, which in turn puts demands on how the knowledge must be represented. This paper describes an industrial prototype—Protein Purification Advisor (PPA)—in the area of protein purification, and how a suitable choice of knowledge representation has allowed us to use the same knowledge for a number of purposes including those mentioned above. Particular interest is laid on the topic of how to represent the heuristic knowledge and how to use it in actual decision-making.     

Learning without lectures: a case study

During a 1995-1996 sabbatical, the authors' long-standing concern about discrepancies between their teaching philosophies and classroom practices reached a crisis. As a result, they decided to offer the fall 1996 Introduction to Psychology course on the World Wide Web. There were several issues to think about. First, the authors saw the potential for a huge impact, since 80 to 85 percent of North Dakota State University students enrol in Psych110, most within their first two years. Second, they decided to design the course so that it could be offered for off-campus distance learning as well as on-campus resident instruction. Third, they decided to minimize overhead for students by using only a Web browser, e-mail, a textbook, and the textbook publisher's demonstration/simulation software. Fourth, they chose to base decisions about course components on published literature covering cognition and teaching. Finally, they built in mid term and final student course evaluation components and a field experiment comparing student attitudes and learning outcome for online versus lecture classes     

Intel's incident-free culture: a case study

The occupational ergonomic program that Intel's newly established manufacturing plant in Israel implemented in 1997 helped prevent injuries and also marked the launch of a whole new approach to ergonomics. A key element in the success of the seven-point program was a strong commitment from management, which came to regard this plan as a vital strategic element in the new plant's success. Comprehensive, top-down planning imposed obligations on all elements in the manufacturing spectrum, from suppliers to contractors to employees. Work requirements were set; cooperation with the plant's occupational health professionals was established; and long-term reporting and instruction systems were developed. Extensive ergonomic training was a crucial factor in integrating ergonomic procedures into the organization's day-to-day activities. Along with this instructional program, ergonomic engineers implemented a strict measuring system to ensure that each ergonomic activity would be performed according to schedule. By the time the factory opened its gates and began to produce, a vigorous ergonomic environment had emerged and employees were displaying an ergonomic mindset that also impinged upon their non-work activities. As a result of the successful implementation of the program, Intel's ergonomic program has become a model for Israeli industry. This paper presents a full ergonomic program that besides supplying the Intel plant with solutions was unique enough to impact the whole Israeli industry.     

Software product lines: a case study

A software product line is a family of products that share common features to meet the needs of a market area. Systematic processes have been developed to dramatically reduce the cost of a product line. Such product‐line engineering processes have proven practical and effective in industrial use, but are not widely understood. The Family‐Oriented Abstraction, Specification and Translation (FAST) process has been used successfully at Lucent Technologies in over 25 domains, providing productivity improvements of as much as four to one. In this paper, we show how to use FAST to document precisely the key abstractions in a domain, exploit design patterns in a generic product‐line architecture, generate documentation and Java code, and automate testing to reduce costs. The paper is based on a detailed case study covering all aspects from domain analysis through testing. Copyright © 2000 John Wiley & Sons, Ltd.     

Tank monitoring: a pAMN case study

The introduction of probabilistic behaviour into the B-method is a recent development. In addition to allowing probabilistic behaviour to be modelled, the relationship between expected values of the machine state can be expressed and verified. This paper explores the application of probabilistic B to a simple case study: tracking the volume of liquid held in a tank by measuring the flow of liquid into it. The flow can change as time progresses, and sensors are used to measure the flow with some degree of accuracy and reliability, modelled as non-deterministic and probabilistic behaviour respectively. At the specification level, the analysis is concerned with the expectation clause in the probabilistic B machine and its consistency with machine operations. At the refinement level, refinement and equivalence laws on probabilistic GSL are used to establish that a particular design of sensors delivers the required level of reliability.     

Applying reliability measurement: a case study

The problem of knowing when to stop testing software is considered, focusing on the strategy of stopping when a reliability level or rate of failure occurrence acceptable to the customer is reached. The system's reliability is monitored throughout the system test, and the system is released to the field only when the measured reliability is at or above this objective. This approach was applied to test-failure data collected on Remote Measurement System-Digital 1, a large telecommunications testing system that had already gone through system test and been released to the field. The RMS-D1 failure data, which consisted of command-response errors versus commands executed, had been routinely collected by the system-test organization during testing. The testing phase analyzed, the load test, was an operational-profile-driven test in which a controlled load was imposed on the system reflective of the system's busy-hour usage pattern. It was found to be feasible to apply the reliability-measurement approach in real time, to systems actually undergoing system test, given a controlled load-test environment.<>     

Assessing architectural evolution: a case study

This paper proposes to use a historical perspective on generic laws, principles, and guidelines, like Lehman’s software evolution laws and Martin’s design principles, in order to achieve a multi-faceted process and structural assessment of a system’s architectural evolution. We present a simple structural model with associated historical metrics and visualizations that could form part of an architect’s dashboard. We perform such an assessment for the Eclipse SDK, as a case study of a large, complex, and long-lived system for which sustained effective architectural evolution is paramount. The twofold aim of checking generic principles on a well-know system is, on the one hand, to see whether there are certain lessons that could be learned for best practice of architectural evolution, and on the other hand to get more insights about the applicability of such principles. We find that while the Eclipse SDK does follow several of the laws and principles, there are some deviations, and we discuss areas of architectural improvement and limitations of the assessment approach.     

Incentives in production: a case study

The motivation, rationale, and experiences of implementing an incentive scheme in a large petrochemical plant in the People's Republic of China for the purpose of conserving the consumption of cooling water is described. Experimental implementation in a section of a plant is described in detail. A few incentive-induced features uncovered after analyzing the experimental data are reported. A mathematical model with several variations is presented. A better predictive property of the incentive scheme in comparison to a more conventional method is proved analytically. The effectiveness of the scheme is shown by the amount of water conserved, and by the management's decision for plantwide adoption of the scheme. Practical issues encountered in experimental implementation, extensions of the scheme to more general situations, and theoretical problem inspired by the experiment are discussed     

Measuring software quality: a case study

The National Security Agency's (NSA) mission is to provide support for the security of the United States. Over the years, the Agency has become extremely dependent on the software that makes up its information technology infrastructure. NSA has come to view software as a critical resource upon which much of the world's security, prosperity, and economic competitiveness increasingly rests. To ensure cost effective delivery of high quality software, NSA has analyzed effective quality measures applied to a sample code base of 25 million lines. This case study dramatically illustrates the benefits of code level measurement activities