极大代数方法在轧钢厂DEDS中的应用

本文用极大代数方法对某轧钢厂建立了离散事件动态系统(DEDS)模型,在周期分析与 配置理论的基础上解决了最优调度与控制问题.     

Experience with fault injection experiments for FMEA

Failure Modes and Effects Analysis (FMEA) is a widely used system and software safety analysis technique that systematically identifies failure modes of system components and explores whether these failure modes might lead to potential hazards. In practice, FMEA is typically a labor‐intensive team‐based exercise, with little tool support. This article presents our experience with automating parts of the FMEA process, using a model checker to automate the search for system‐level consequences of component failures. The idea is to inject runtime faults into a model based on the system specification and check if the resulting model violates safety requirements, specified as temporal logical formulas. This enables the safety engineer to identify if a component failure, or combination of multiple failures, can lead to a specified hazard condition. If so, the model checker produces an example of the events leading up to the hazard occurrence which the analyst can use to identify the relevant failure propagation pathways and co‐effectors. The process is applied on three medium‐sized case studies modeled with Behavior Trees. Performance metrics for SAL model checking are presented. Copyright © 2011 John Wiley & Sons, Ltd.     

Quantifying security threats and their potential impacts: a case study

In earlier works we presented a computational infrastructure that allows an analyst to estimate the security of a system in terms of the loss that each stakeholder stands to sustain as a result of security breakdowns. In this paper we illustrate this infrastructure by means of an e-commerce application.     

Data and reports: Contents design and users allocation

When a common information system should supply data in a batch processing mode to many various users, the systems analyst is faced with the problem of allocating data among various reports and reports among different users. The traditional approach to that problem is very unstructured. Such a problem is formulated here in a nonlinear binary programming model. Four alternative techniques of solving the model are presented, followed by an example. The main contribution is a systematic and analytic approach toward a major problem in information systems design.     

Wearing two hats: analyst-managers for small software projects

With the evolution of software development, companies have changed their project methodology and are asking IT employees to evolve with them. The business analyst talks to users, ironing out the details of what they wanted and balancing that wish list against what an IT system could economically or practically deliver. The business analyst also ensures that users develop business processes to support the software. The actual task of writing the software falls to a project manager and his team of software developers. Today, companies commonly ask IT managers to assume the business analyst role in addition to their duties as project manager, especially in small projects. This article discusses how IT managers can successfully navigate the thin line between business analyst and project manager.     

Power: A critical systems development factor

Information system development methodologies for complex management support systems require the information analyst to utilize concepts and techniques which are frequently viewed as being too intangible and abstract. The analyst's knowledge and techniques must accommodate the increased variations and complexities which commonly exist for management support systems at all levels of management.In this article, power is examined as an information systems development concept and as a basis for a technique which will enable the information analyst to identify the information requirements for management support systems more effectively.     

A SYSTEMS APPROACH TO PLANNING IN ORGANIZATIONS-DEVELOPING A COLLABORATIVE RESEARCH STUDY

Abstract

Some of the problems in developing a holistic systems approach to the question of planning in organizations and the part that the in-house analyst should play in the planning process are discussed in this article. The question of how to match the organizational system to the particular human characteristics of those who will operate it is asked. It is illustrated that the analyst, in order to be successful, needs to take an overall holistic view of the problem of his or her organization. The author then presents a discussion of a research project currently being initiated at the International Institute for Applied Systems Analysis.     

Intrusion detection alarms reduction using root cause analysis and clustering

As soon as the Intrusion Detection System (IDS) detects any suspicious activity, it will generate several alarms referring to as security breaches. Unfortunately, the triggered alarms usually are accompanied with huge number of false positives. In this paper, we use root cause analysis to discover the root causes making the IDS triggers these false alarms; most of these root causes are not attacks. Removing the root causes enhances alarms quality in the future. The root cause instigates the IDS to trigger alarms that almost always have similar features. These similar alarms can be clustered together; consequently, we have designed a new clustering technique to group IDS alarms and to produce clusters. Then, each cluster is modeled by a generalized alarm. The generalized alarms related to root causes are converted (by the security analyst) to filters in order to reduce future alarms’ load. The suggested system is a semi-automated system helping the security analyst in specifying the root causes behind these false alarms and in writing accurate filtering rules. The proposed clustering method was verified with three different datasets, and the averaged reduction ratio was about 74% of the total alarms. Application of the new technique to alarms log greatly helps the security analyst in identifying the root causes; and then reduces the alarm load in the future.     

Automated Barchart Construction

The task of work sequencing and assignment of personnel is generally done manually. The need for a system which can reduce this overhead cost and provide work plans (barcharts) having improved manpower utilization has been recognized for many years. This article describes a technique developed for use as a computer system of “Automated Barchart Construction” (ABC). This system improves the effectiveness of the industrial engineering analyst by reducing the analyst effort required to produce and maintain barcharts and providing new barcharts soon after job planning is complete which reflect an improved manpower utilization.     

Ambiguity and tacit knowledge in requirements elicitation interviews

Interviews are the most common and effective means to perform requirements elicitation and support knowledge transfer between a customer and a requirements analyst. Ambiguity in communication is often perceived as a major obstacle for knowledge transfer, which could lead to unclear and incomplete requirements documents. In this paper, we analyze the role of ambiguity in requirements elicitation interviews, when requirements are still tacit ideas to be surfaced. To study the phenomenon, we performed a set of 34 customer–analyst interviews. This experience was used as a baseline to define a framework to categorize ambiguity. The framework presents the notion of ambiguity as a class of four main sub-phenomena, namely unclarity, multiple understanding, incorrect disambiguation and correct disambiguation. We present examples of ambiguities from our interviews to illustrate the different categories, and we highlight the pragmatic components that determine the occurrence of ambiguity. Along the study, we discovered a peculiar relation between ambiguity and tacit knowledge in interviews. Tacit knowledge is the knowledge that a customer has but does not pass to the analyst for any reason. From our experience, we have discovered that, rather than an obstacle, the occurrence of an ambiguity is often a resource for discovering tacit knowledge. Again, examples are presented from our interviews to support this vision.     

Optimal acceptance sampling plans for log-location-scale lifetime models using average risks

Assuming that the probability of obtaining a defective unit in a production process, p, is not constant, a versatile methodology is presented for determining optimal failure-censored reliability sampling plans for log-location-scale lifetime models. The optimization procedure to decide the acceptability of a product is usually sufficiently accurate for the most widely used parametric lifetime models, such as the Weibull and lognormal distributions, and fairly robust to small deviations in the prior knowledge. Moreover, lower and upper bounds on the optimal sample size, and the corresponding acceptance constants, are derived in closed-forms. The proposed approach extends the traditional sampling plans to those cases in which appreciable prior information on p exists, and also allows the analyst the flexibility to delimitate the range of p and to incorporate into the reliability analysis prior impartiality between the producer and the consumer. In addition, the practitioners may achieve substantial savings in sample size, better information on the production process and better assessment of the true producer and consumer risks. An example related to the acceptability of a certain kind of gyroscope is included for illustrative purposes. Various practical prior distributions are considered to describe the random fluctuations in the proportion defective.     

A design language for the definition of a retrieval system interface for casual users of a relational database

A design language is described that enables the information analyst to produce a tailor-made interface for the casual user of a relational database system. The ideas are extended to show how ad hoc retrieval systems can be constructed from the building blocks incorporated in the relational model.     

Predicting pilot error: Testing a new methodology and a multi-methods and analysts approach

The Human Error Template (HET) is a recently developed methodology for predicting design-induced pilot error. This article describes a validation study undertaken to compare the performance of HET against three contemporary Human Error Identification (HEI) approaches when used to predict pilot errors for an approach and landing task and also to compare analyst error predictions to an approach to enhancing error prediction sensitivity: the multiple analysts and methods approach, whereby multiple analyst predictions using a range of HEI techniques are pooled. The findings indicate that, of the four methodologies used in isolation, analysts using the HET methodology offered the most accurate error predictions, and also that the multiple analysts and methods approach was more successful overall in terms of error prediction sensitivity than the three other methods but not the HET approach. The results suggest that when predicting design-induced error, it is appropriate to use a toolkit of different HEI approaches and multiple analysts in order to heighten error prediction sensitivity.     

COSSAC: a framework for analyzing and configuring secure computer facilities

Checklist have historically provided the vehicle for analyzing the security posture of a computer facility but they have at least two deficiencies: they cannot take into account the unique operational and environmental requirements of a particular facility nor can they rationalize the interaction between various protective measures. The system to be described is a computer program that carried on a structured dialogue with the analyst to obtain information about existing safeguards and perceived needs; then it issues warnings and suggestions directed at upgrading the security of the facility. It is written in a non-procedural language that makes it easy to change. Its knowledge base can therefore grow with experience and track advances in the state of the art.     

Adaptive reallocation of cybersecurity analysts to sensors for balancing risk between sensors

Cyber Security Operations Center (CSOC) is a service-oriented system. Analysts work in shifts, and the goal at the end of each shift is to ensure that all alerts from each sensor (client) are analyzed. The goal is often not met because the CSOC is faced with adverse conditions such as variations in alert generation rates or in the time taken to thoroughly analyze new alerts. Current practice at many CSOCs is to pre-assign analysts to sensors based on their expertise, and the alerts from the sensors are triaged, queued, and presented to analysts. Under adverse conditions, some sensors have more number of unanalyzed alerts (backlogs) than others, which results in a major security gap for the clients if left unattended. Hence, there is a need to dynamically reallocate analysts to sensors; however, there does not exist a mechanism to ensure the following objectives: (i) balancing the number of unanalyzed alerts among sensors while maximizing the number of alerts investigated by optimally reallocating analysts to sensors in a shift, (ii) ensuring desirable properties of the CSOC: minimizing the disruption to the analyst to sensor allocation made at the beginning of the shift when analysts report to work, balancing of workload among analysts, and maximizing analyst utilization. The paper presents a technical solution to achieve the objectives and answers two important research questions: (i) detection of triggers, which determines when-to reallocate, and (ii) how to optimally reallocate analysts to sensors, which enable a CSOC manager to effectively use reallocation as a decision-making tool.     

WESTT (workload, error, situational awareness, time and teamwork): an analytical prototyping system for command and control

Modern developments in the use of information technology within command and control allow unprecedented scope for flexibility in the way teams deal with tasks. These developments, together with the increased recognition of the importance of knowledge management within teams present difficulties for the analyst in terms of evaluating the impacts of changes to task composition or team membership. In this paper an approach to this problem is presented that represents team behaviour in terms of three linked networks (representing task, social network structure and knowledge) within the integrative WESTT software tool. In addition, by automating analyses of workload and error based on the same data that generate the networks, WESTT allows the user to engage in the process of rapid and iterative “analytical prototyping”. For purposes of illustration an example of the use of this technique with regard to a simple tactical vignette is presented.     

An object-oriented tool for function point analysis

Abstract: Function points have become an accepted measure of software size and are becoming an industry standard. However, the application of function point analysis is fairly complex and requires experience and a good understanding to apply it in a consistent manner. This paper describes the development of a knowledge-based, object-oriented system to assist an analyst in performing function point analysis. The objective of the function point analysis (FPA) tool is to allow an analyst to estimate system size in function points without having extensive training or experience using the function point method. The FPA tool uses information available in a functional specification that is a product of the requirements analysis phase of the software development life cycle. An object-oriented model was used to represent the functional requirements of a software system.     

A methodology which requires user participation in the design of information systems

User participation in the design of computerized information systems is an accepted philosophy. The goal is to enhance the appreciation for and thus utility of the new system. In reality, however, system design procedures tend not to achieve this goal. The reason is that participation is implemented half heartedly, allowing the user to ask and answer questions, but not get involved in the design. This paper presents an adaptation of Nadler's “IDEALS” approach to the design of information systems. The approach presented is a five step procedure which removes the user from his daily information related activities and allows him to hypothesize an idealized use of information in his job. The approach then proceeds to allow the user and analyst to creatively implement a close approximation to the ideal design target.     

Knowledge-based support in help-desk environments

How much does a knowledge based system improve help desk interactions? To investigate the relationship between a KBS and a help desk and to provide a first step in determining the return on investment of KBSs in general, we conducted a study that showed as accurately as possible the impact of a KBS on one of Hewlett-Packard's customer support centers. We organized the study to verify three main assumptions: it takes less time to resolve a call when the analyst uses the KBS; the time saving shows up as a weekly decrease in overall interaction time; using a KBS allows the analyst to solve more kinds of problems than not using it