Measuring computer software reliability

Under certain conditions, traditional hypothesis-testing techniques may be used as a management tool by software developers or software purchasers who wish to insure that their packages have some specified reliability level. These conditions are: (1) the existence of independent collections of test data, (2) a way of determining the correctness of processing of these collections, and (3) a way of randomly selecting test data.Two basic approaches have been described. In a fixed sample size test, the user decides on the reliability desired. He can then determine the number of test cases which must be examined and the acceptance/rejection criteria. In a sequential test, the desired reliability level is again pre-determined, but samples are tested one at a time until an accept/reject decision can be made.Experiments with a large amount of error data derived from six separate systems indicate that reliability results derived from these models are consistent with actual reliability figures.Most current acceptance procedures are based on a naive assumption that a large program can be exhaustively tested and delivered in an error-free condition. Because these expectations cannot be fulfilled, the manager of a software development project or the purchaser of a software product is provided with no quantitative information on which to base an acceptance decision and is thus forced to make these decisions based mostly on intuition and his own experience in similar situations. These models allow one to replace these intuition-based decisions with quantitatively-based decisions and thus constitute an important contribution to the science of management of software development efforts.     

Analysis of Buffering Techniques in MRP Systems with a Matrix Loading Model

This paper addresses the development of a matrix model for the initial loading procedure in material requirement planning systems with variable lead time. This model expresses the relationship between the planned production quantity in the Master Production Schedule and the production lead time required. Using this model, an analysis of the functions of buffering techniques before loading are discussed. Methods for allocating safety stock and safety lead time using the service level approach are presented to accommodate quantity or lead-time uncertainties. The matrix model is used to study fixed-lead-time loading. The relationships between fixed-lead-time loading and variable-lead-time loading are examined. Methods for allocating buffering quantities for fixed-lead-time loading are developed.     

Mechanisms of tubulin modification by phosphatidylcholine hydroperoxides

The interaction of lipid peroxides with cellular proteins has been postulated to contribute to cellular aging. A potential target for such effects is tubulin, the building block of microtubules. We examined the concentration-dependent effects of phosphatidylcholine hydroperoxides on the ability of tubulin to polymerize into microtubules. The results demonstrated that even very low concentrations of peroxides were sufficient to interfere with the tubulin and, therefore, the microtubule function. Decreased tubulin activity (as measured by tubulin GTPase activity) showed correlation with the modification of methionine and cysteine in tubulin and a change in the tubulin conformational state as indicated by fluorescence and ultraviolet spectroscopic measurements. As no effect on electric conductivity was observed, indicating that modulation of ionic binding was not involved, the interaction mechanism may be a hydrophobic one.     

Beyond parallel play: Science befriending the art of method acting to advance healing relationships.

Research underscores the central role of factors in healing that appear to relate to the therapeutic relationship. These nonspecific or common factors and placebo effects are often overshadowed by an emphasis in the field on particular empirically supported therapies. Yet relationship variables account for a greater proportion of the variance in treatment outcomes than the technical intervention employed, representing a notable blind spot in our science and, by extension, our practice. As a consequence, clinical instruction in psychology and in the health professions more broadly generally lacks adequate specificity with respect to how to cultivate a healing relationship. Through the elaboration of several techniques derived from theatrical traditions, the authors propose that method acting and similar schools of drama provide a method for honing clinical skills in these areas that is amenable to empirical scrutiny. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

在线检测与分析 快速发现不可见的电学缺陷

在Fab里，在经过特别设计的短流程测试晶圆上进行的快速电学测试和自动FIB／SEM缺陷分析可以将不可见缺陷探测与分析的时间降低一个数量级，并且对不同的设计参数非常敏感，因而有足够的样本来做重要的统计评估。     

Monitoring the status of forests and rangelands in the Western United States using ecosystem performance anomalies

The effects of land management and disturbance on ecosystem performance (i.e. biomass production) are often confounded by those of weather and site potential. The current study overcomes this issue by calculating the difference between actual and expected ecosystem performance (EEP) to generate ecosystem performance anomalies (EPA). This study aims to delineate and quantify average EPA from 2000–2009 within the Greater Platte and Upper Colorado River Basins, USA. Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) images averaged over the growing season (GSN) served as a proxy of actual ecosystem performance. Yearly EEP was determined with rule-based piecewise regression tree models of abiotic data (climate, soils, elevation, etc.), independently created for each land cover. EPA were calculated as the residuals of the EEP to GSN relationship, and characterized as normal performing, underperforming, and overperforming at the 90% confidence level. Validation revealed that EPA values were related to biomass production (R ² = 0.56, P = 0.02) and likely to the proportion of biomass removed by livestock in the Nebraska Sandhills. Overall, 60.6% of the study area was (normal) performing near its EEP, 3.0% was severely underperforming, 5.0% was highly overperforming, and the remainder was slightly underperforming or overperforming. Generally, disturbances such as fires, floods, and insect damage, in addition to high grazing intensity, result in a negative EPA. Conversely, mature stands and appropriate management often result in positive EPA values. This method provides information critical to land managers to evaluate the appropriateness of previous management practices and restoration efforts and quantify disturbance impacts. Results are at a scale sufficient for many of the large management units of the region and for locating areas needing further investigation. Applications of EPA data to monitoring invasive species, grazing impacts, and vulnerability to plant community shifts have been suggested by land management professionals.     

Design of transient experiments for identification of fixed bed thermal transport properties

The utility of using optimal input signals to improve the parametric information content in a transient experiment is explored. This work extends the statistical design concepts that have proven useful in steady state model building studies to a dynamic environment. The methodology is demonstrated for the identification of thermal transport properties in an adiabatic packed bed. The effects of the choice of measurements, initial parameter values and accuracies, and performance criteria are assessed. The results indicate that optimal dynamic experiments can offer considerable improvement over present practice.     

Tryptophan and tonic immobility in chickens: Effects of dietary and systemic manipulations.

Consistent with a serotonergic-midbrain raphe model of tonic immobility, 4 experiments designed to evoke changes in serum tryptophan produced reliable effects on the duration of the response in a total of 114 Production Red chickens. Systemic injections of tryptophan, the dietary precursor of serotonin, led to a dose-dependent increase in immobility, with optimal effects observed within 30 min after injection. Dietary depletion of endogenous tryptophan attenuated the duration of immobility, and a diet completely free of tryptophan, but supplemented with niacin, practically abolished the reaction. Dietary replacement of tryptophan reinstated the response. In a 5th experiment with 20 Ss, tryptamine, an alternative metabolic by-product of tryptophan, had no effect on immobility. Data are discussed in light of evidence showing serotonergic involvement in tonic immobility. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of work rates, energy expenditure, and perceived exertion during a 1-h vacuuming task with a backpack vacuum cleaner and an upright vacuum cleaner

The purpose of this study was to evaluate two types of industrial vacuum cleaners, in terms of cleaning rates, energy expenditure, and perceived exertion. Twelve industrial cleaners (six males and six females, age 28-39 yr) performed two 1-h vacuuming tasks with an upright vacuum cleaner (UVC) and a backpack vacuum cleaner (BPVC). Measures for oxygen uptake (VO2) and ratings of perceived exertion (RPE) were collected continuously during the 1-h vacuuming tasks. Cleaning rates for the UVC and BPVC were 7.23 and 14.98 m2min(-1), respectively. On a separate day subjects performed a maximal treadmill exercise test to determine their maximal aerobic capacity (peak VO2). Average absolute energy costs (in Metabolic equivalents), relative energy costs of the vacuum task compared to the subjects' maximal aerobic capacity (% peak VO2), and RPE responses for the 1-h vacuuming tasks were similar between vacuum cleaners, but % peak VO2 and RPE values differed between genders. These results indicate that the BPVC was more efficient than the UVC. With the BPVC, experienced workers vacuumed at a cleaning rate 2.07 times greater than the UVC and had similar levels of energy expenditure and perceived effort, compared to the slower cleaning rate with the UVC.     

Collaborating with a Medical School to Assess Occupational Health and Safety Content in an Engineering Curriculum

A research center in the College of Medicine assisted the Biosystems and Agricultural Engineering Department in the assessment of occupational health and safety instruction in the undergraduate agricultural engineering curriculum. An interdisciplinary team developed a questionnaire to explore three facets of health and safety instruction: 1) content and placement in the curriculum, 2) reasons for teaching occupational health and safety, and 3) adequacy of teaching resources. The questionnaire was pilot tested using agricultural engineering faculty and technicians from a large land grant university. Responses to the questionnaire revealed strengths and weaknesses in the curriculum regarding occupational health and safety instruction. The questionnaire will be expanded and further tested with a broader subject base. This cooperative effort demonstrates that medical schools can be a valuable resource to engineering schools who are looking for ways to improve occupational health and safety instruction in their curricula.