An Objective Function to Evaluate Performance of Human–Robot Collaboration in Target Recognition Tasks

Robotic systems in unstructured environments must cope with unknown, unpredictable, and dynamic situations. Inherent uncertainty, and limited sensor accuracy and reliability impede target recognition performance. Introducing a human operator into the system can help improve performance and simplify the robotic system. In this paper, four basic levels of collaboration were defined for human-robot collaboration in target recognition tasks. An objective function that includes operational and time costs was developed to quantify performance and determine the best collaboration level. Signal detection theory was applied to evaluate system performance. The optimal collaboration level for different cases was determined by using numerical analyses of the objective function. The findings indicate that the best system performance, the optimal values of performance measures, and the best collaboration level depend on the task, the environment, human and robot parameters, and the system characteristics. For the tested cases, the manual level was never the best collaboration level for achieving the optimal solution. The autonomous level was the best collaboration level when robot sensitivity was higher than human sensitivity. In general, collaboration of human and robot in target recognition tasks will improve upon the optimal performance of a single human detector.     

Electrostatic-Discharge Awareness & Control?An R&M 2000 Issue

As weapon systems become more sophisticated to meet multiple complex hostile threats, there will be an increasing reliance upon a high density of analog and digital microelectronic components, modules, and subsystems. Hybrid microelectronics are moving toward submicron geometries for semiconductor components, multilayer interconnects, and higher component densities on larger area substrates. This miniaturization increases the susceptibility of microelectronic circuitry to electrical overstress (EOS) and electrostatic discharge (ESD). Since EOS and ESD directly affect reliability and maintainability, procedures must be developed to account for them in engineering design, manufacturing, and testing. Over the past several years, there has been a concerted effort to raise ESD awareness at all levels of design and production at Motorola and other electronic firms. This paper briefly describes what measures should be considered and presents examples of their implementation at Motorola to increase reliability, lower costs, and reduce maintainability factors.     

Reliability modeling for expansion-planning of electric-powerplants

The author presents a simple analytic approach for solving the problem of expansion planning of electric power plants. The relationship between the long-range generation investment and the plant size is studied to determine generation capacity. The reliability level, as an important limiting factor of the expansion planning process, is discussed and the corresponding systems costs are determined based on the reliability specification. The stochastic behavior of each plant is represented using a six-state model. The reliability level of the generation system is evaluated using a recursive convolution of the weekly load duration curve with the stochastic availability of the generating units. Central to the reliability calculation is the selection of the unit size; the relationships between plant size and the corresponding investment and production cost are calculated for each expansion alternative. The techniques are also applied to a practical power system and a comparative study is used to select the optimal plant size     

Computer Reliability Optimization System

The short electronic system development time, the acute competitiveness, the emphasis on lower costs, and the insistence upon high reliability has fostered practical computerization of the manager's and designer's reliability function. This computerization attempts to achieve feasible system optimization. The Computerized Reliability Optimization System (CROS) was developed by Hoffman Electronics Corporation's Computer-Aided-Design, Analysis, and Reliability Group to provide an optimum solution to the present system reliability methods. CROS is a comprehensive set of computer programs and a complementary design and management method for handling the total reliability function from proposal effort through the production and field-data analysis. The organization, application, feasibility, and results of CROS are discussed.     

晶圆级芯片尺寸封装技术

尺寸缩减几乎是电子封装技术应用的主要驱动力之一。高功能性和高可靠性与尺寸缩减的相互作用,也是所有微电子系统的决定因素。因此,最佳产品设计、最小单芯片封装和板技术的最佳结合,将提供最佳解决方案。晶圆级CSP将是匹配所有电子系统要求、降低总成本的单芯片封装技术的最佳方案。     

Designing a Reliable Power System: Hydro-Quebec's Integrated Approach

Hydro-Que/spl acute/bec's transmission system is among the most extensive and complex transmission networks in North America. The system's design was improved over the last few years using an optimization process based on acquired experience as well as customers' expectations. Hydro-Que/spl acute/bec's transmission system is currently designed in accordance with four major guiding principles based on a successive line of defense concept designed to counter events that are increasingly more severe but also increasingly more rare. These major guiding principles are a direct reflection of the level of risk that society accepts to tolerate in relation to the costs involved by higher reliability requirements. Que/spl acute/bec's specific context, which is characterized by long transmission lines, harsh weather, and customers' heavy reliance on electricity for their heating needs, means that very high security standards must be used in the system design. To obtain a level of reliability on par with that of our neighbors' systems, however, requires more stringent criteria and standards. This paper will describe the design philosophy of Hydro-Que/spl acute/bec's power system, the underlying major guiding principles, and the defense plans designed to ensure its reliability.     

A practical method of optimizing system life cycle costs vs availability

The effect will be shown, on availability and life cycle costs by equipment reliability, maintainability, system configuration and technician response time to equipment failures. Guidelines will be given to assist the project manager in determining best system parameters for minimizing life cycle costs for a particular application.     

Reengineering claims processing using probabilistic inductivelearning

With health care costs in the United States skyrocketing, and $.25 of every health care dollar being spent on systems and claims administration, technological advances such as electronic claims filing are being advocated as cost-reducing measures. These improvements alone, however, will not significantly reduce costs unless they are accompanied by revisions in the entire claims processing system. This study explores the reliability and utility of probabilistic inductive learning (PrIL), a statistically enhanced decision tree algorithm, for improving the decision-making process at the New York State Workers' Compensation Board (WCB). Results indicate that the PrIL algorithm is favorably comparable to both the purely statistical and the classical decision tree methodologies, with the added advantages of easy to understand rules and user-defined reliability measures for each of those rules. Given the appropriate information regarding the relative value of correct and incorrect classification of cases in the WCB system, PrIL can be used to accurately assist in the decision making process in terms of reducing cost, predicting and enhancing quality and case outcomes in managed care practices     

Reliability Investment and Life-Cycle Cost

The reliability of avionic equipment profoundly influences life-cycle cost; the level of reliability attained largely depends upon the investment in reliability programs during development. As more investment is made in reliability improvement, some cost elements increase and others decrease. These opposing cost trends yield a unique minimum life-cycle cost (LCC). In order to find the level of investment in a reliability improvement program that minimizes LCC, the Reliability Investment Optimization (RIO) model has been developed. It identifies, for a particular avionic system, the level of reliability investment that minimizes the LCC of the equipment. This model employs a reliability-growth relationship based on the Duane model. The RIO model uses this reliability growth pattern to compute LCC as a function of MTBF (mean time between failures) where LCC comprises: 1) research, development, test and evaluation (RDT&E), 2) procurement, and, 3) operations and support (O&S). The RIO model uses summary level data that are appropriate for the timeframe of its most advantageous use, i.e., prior to detail design of the system. The degree of accuracy for the input parameters need not be high because results are not very sensitive to data accuracy. The model's results thus are quite stable. The RIO model was designed with avionic systems in mind. However, the model applies to a wider range of systems. Certain assumptions should be particularly scrutinized in extending usage beyond avionics, e.g., Poisson demand assumption versus a wearout failure pattern (failure rate increases over time), scheduled maintenance, and LCC element breakdown.     

Wafer-level chip size package (WL-CSP)

Size reduction is one of the main driving forces for packaging in nearly all electronic applications. The interaction of size reduction with highest functionality and high reliability is also predominant for all microelectronic systems. Therefore a synergism of optimal product design, smallest single chip package and board technology will give the best solution. Wafer level CSP will be the best solution for single chip packaging matching all requirements for electronic systems and reducing total cost     

Engineering—Economic analysis of electric power systems

This state-of-the art paper sets out recent developments in the engineering-economic analysis of electric power systems, especially the formulation of optimal investment and pricing policies. The basic economic principle is that electricity services should be provided in a manner which maximizes the net benefits of consumption of society as a whole. In investment policy, this principle may often be reduced to the simpler rule of minimizing total costs subject to specific constraints. In pricing policy, rates should reflect the marginal costs of supply, thus ensuring that economic efficiency criteria are satisfied. However, these marginal costs must be systematically adjusted to yield a practical tariff structure that meets other policy objectives. Several case studies are provided which illustrate the practical application of the methodology to optimize investment planning and reliability, system losses, and tariffs.     

Reliability of voting in fault-tolerant software systems for smalloutput-spaces

Under a voting strategy in a fault-tolerant software system there is a difference between correctness and agreement. An independent N -version programming reliability model which distinguishes between correctness and agreement is proposed for treating small output spaces. An alternative voting strategy, consensus voting, is used to treat cases when there can be agreement among incorrect outputs, a case which can occur with small output spaces. The consensus voting strategy automatically adapts the voting to various version reliability and output-space cardinality characteristics. The majority-voting strategy provides reliability which is a lower bound, and the 2-out-of-n voting strategy provides reliability which is an upper bound, on the reliability by consensus voting. The reciprocal of the cardinality of output space is a lower bound on the average reliability of fault-tolerant system versions below which the system reliability begins to deteriorate as more versions are added     

基于构件的软件测试中测试用例分配优化研究

探讨了软件测试中每个构件软件的可靠性灵敏度已知,而测试资源受约束时,如何合理分配测试用例以提高构件软件可靠性的最优化问题.分析了传统的基于可靠性灵敏度的构件软件可靠性优化方法(RPP策略),在此基础上提出一种考虑测试代价的改进的构件软件可靠性优化方法(RPP-c策略).证明了RPP-c策略中带约束的测试用例最优分配问题是一个NPC问题,给出了动态规划求解方法,从理论上验证了RPP-c策略是最优的.     

Expanding Maintainability Concepts and Techniques

As electronic systems continue to increase in cost and complexity, the search for more effective maintainability concepts and techniques takes on added momentum. Recent contracts often require maintainability to be predicted during design and the predictions later validated by demonstration. To accomplish these new requirements, maintainability must develop a new and closer relationship with reliability and design engineering. This new relationship will not be difficult when probabilities of maintenance success are applied to the corrective maintenance repair time predictions. Probabilities of maintainability and reliability would then be compatible and thus effectively utilized to determine availability, the prime index for systems effectiveness. Changing maintainability requirements are discussed along with the more familiar prediction methods, as well as how these concepts and techniques can be expanded to predict the probability of maintenance success.     

Microelectronic System Reliability Prediction

The paper reviews the US MIL-HDBK-217 (MH-217) method of part stress-analysis failure-rate prediction for microelectronic systems and investigates the extent to which the MH-217 failure-rate formula is compatible with the physics of actual failure modes. A new formula is proposed which takes account separately of the reliability of the microelectronic devices in a system and of the system-level determinants of reliability. It is simpler than the current MH-217 formula, and more useful. It enables the system level aspects such as reliability program activities to be taken into account in the prediction, and allows better correlation to be made between part test and system test data. An example applies the new formula to a typical microelectronic system. By considering separately the failure physics of parts and the system level determinants, reliability prediction can be made a more useful tool both for part stress analysis and for reliability program management. The model would enable better correlations to be made between part and system test results. More work needs to be done to refine and validate the parameters. For high-reliability programs with closely controlled maintenance or with no maintenance, the use of a decreasing failure rate model for part failures should be considered. The failure rate formulae for other electronic parts used in microelectronic systems would also need to be reviewed, but apart from removal of the environmental factor and reduction in the failure rate values proportionate to that proposed for microelectronic parts, no changes should be necessary.     

Electronic Part Failure Rates in Space Environments

Much conjecture exists regarding the special effects of space environments as reliability stressors on common electronic parts. To understand the unique risks associated with these additional factors, it is useful to envision their presence as superimposed sources of activation energy. This, in turn, demands a general mathematical model for part failure rate synthesis which relates statistical risk with energy level. Such a mathematical model has been developed and is worthy of close examination from the view-point of additional space environment risks. Thus, an energy level concept affords mathematical equations from which the statistical risks in ``unproven' operational environments can be inferred from an extrapolation of a wealth of conventional operational experience. This paper contends that advances in the art of space material test and evaluation must have their roots in a comprehensive understanding of terrestrial tests and statistical failure rate criteria. Any useful comprehension must be based upon a rank order of part stressors where ground environment factors are essential prerequisites. Once examined from an energy viewpoint, failure tendencies and their underlying material mechanisms can be usefully depicted mathematically using energy as a helpful common denominator. It remains then to deliberate upon the appropriate material test evidences to establish tables of part usage risk for space environments with the same level of completeness as has been established for terrestrial operating conditions.     

NRLA & MOD-Metric Models as Aids in Design Decisions

This paper reports partial results and extensions of a study at Clemson University from 1980 December to 1982 May. The purpose was to develop an integrated model set to aid in evaluating design alternatives on the availability and logistic support requirements of major weapon systems. The model set includes the Network Repair Level Analysis (NRLA) and MOD-Metric models. System design decisions concern the nominal reliability of components, the extent to which components are hierarchially designed, the accessibility of components, and whether the component will be repaired or discarded when it fails. System design includes the design of the logistic support system and its relation to the hardware. Design alternatives should be carefully investigated to determine the effects that each would have on ownership costs, performance, and availability. This model set was applied to the components of the air refueling boom of the KC-135A tanker aircraft. The 2-echelon, 2-indenture inventory system used at times by the US Air Force is assumed. In particular we report: 1) the effects of component reliability on spare stock levels and spare parts costs, and 2) the impact of component reliability on the level at which repair takes place. The models have similar data requirements and they yield useful conclusions. However, there are some difficulties. The spares decisions from MOD-Metric are not necessarily compatible with NRLA because the MOD-Metric analysis is far more sophisticated.     

R&M 2000 and Environmental Stress Screening

The United States Air Force, Army, and Navy have established the need for Environmental Stress Screening (ESS). The Air Force policy statement issued 1986 November imposed the provision that all fielded major electronic systems must deliver 2000 hours failure free. To accomplish this will require changes in design, producibility, and manufacturing attitudes. Defectives must be removed in the factory, at the most cost effective point in the production cycle. This will require assessing failures from the field, then developing a system to identify these defectives in the factory, at the lowest level of assembly. Poor reliability rooted in high component failure rates leads to premature equipment failures. Fielded systems and spares provisioning with resultant maintenance actions cost heavily during each year of life. The result is that the spares provisioning & logistic support is now exceeding 50 percent of the defense allocation (1984 and 1985 budgets). Cost increases result from poor equipment reliability. Today, systems originally contracted to deliver over 500 hours mean time-between-failures (MTBF) are delivering less than 50 hours MTBF, (Navy Maintenance Material Management ``3M' report). Excessive failure of components is a major cause of reduced life of equipment. Most maintenance actions involve the replacement of piece parts. The roots of this problem lie in the factory. Manufacturers are not removing defectives early in the product design/production cycle. Because of inadequate testing, most defectives are not detected in the factory. Failures are then precipitated in the field.     

A review on thermal cycling and drop impact reliability of SAC solder joint in portable electronic products

Currently, the portable electronic products trend to high speed, light weight, miniaturization and multifunctionality. In that field, solder joint reliability in term of both drop impact and thermal cycling loading conditions is a great concern for portable electronic products. The transition to lead-free solder happened to coincide with a dramatic increase in portable electronic products. Sn–Ag–Cu (SAC) is now recognized as the standard lead free solder alloy for packaging interconnects in the electronics industry. The present study reviews the reliability of different Ag-content SAC solder joints in term of both thermal cycling and drop impact from the viewpoints of bulk alloy microstructure and tensile properties. The finding of the study indicates that the best SAC composition for drop impact performance is not necessarily the best composition for optimum thermal cycling reliability. The level of Ag-content in SAC solder alloy can be an advantage or a disadvantage depending on the application, package and reliability requirements. As a result, most component assemblers are using at least two (and in many cases even more) lead-free solder sphere alloys to meet various package requirements.     

Prerequisites to manufacturing thin-film photovoltaics

In order to compete with established crystalline silicon technologies, thin-film photovoltaics must achieve comparable performance with the promise of substantially lower cost. Low costs will only be achieved with manufacturing volumes of at least several MW_p per year. Due to the high investment required for such a factory, there are a number of prerequisites that must be demonstrated to reduce the risk of this investment. The product requirements must be clearly identified, and are likely to be dictated by the existing silicon technologies. The process must be shown to be capable of producing a high-efficiency, high-yield, stable product. Estimated manufacturing costs must be substantially lower than the costs projected for the crystalline silicon competition to justify the investment in an unproven technology. Once these prerequisites are satisfied, the increase in volume to a manufacturing scale remains a challenge due to the specialized nature of the equipment needed to perform these new processes. Nonetheless, many of these prerequisites have now been demonstrated and new thin-film manufacturing facilities are being constructed. © 1997 John Wiley & Sons, Ltd.