Evaluation and comparison of estimation methods for failure rates and probabilities

An updated parametric robust empirical Bayes (PREB) estimation methodology is presented as an alternative to several two-stage Bayesian methods used to assimilate failure data from multiple units or plants. PREB is based on prior-moment matching and avoids multi-dimensional numerical integrations. The PREB method is presented for failure-truncated and time-truncated data. Erlangian and Poisson likelihoods with gamma prior are used for failure rate estimation, and Binomial data with beta prior are used for failure probability per demand estimation. Combined models and assessment uncertainties are accounted for. One objective is to compare several methods with numerical examples and show that PREB works as well if not better than the alternative more complex methods, especially in demanding problems of small samples, identical data and zero failures. False claims and misconceptions are straightened out, and practical applications in risk studies are presented.     

Identifying software project risks in Nigeria: an International Comparative Study

We report a study where software project risk factors were solicited in Nigeria. The study repeats a research design, which has been used in a Delphi study in the U.S., Finland, and Hong Kong to rank software development risks. The study produces a rank-order list of software risk factors and compares results with the earlier study, showing significant differences. Obtained rankings signal the importance of the infrastructure related and socio-economic software risks in developing countries like Nigeria. This demonstrates the importance of understanding the broader socio-economic context in identifying and managing software risks. The study also shows that some risks in Nigeria are located on a different scale. The choice of contingent mitigation strategies of project managers play a less important role, because the risks are so deeply engrained with the poor quality of basic infrastructure services.     

Effects of latitude and weather conditions on sugars,fruit acids and ascorbic acid in currant (Ribes sp.) cultivars

BACKGROUND: Sugars, acids and vitamin C are essential components influencing the sensory and nutritional properties of currants (Ribes sp.). In this study the effects of growth latitude and weather conditions on these components in red, white and green currant cultivars were systematically investigated for the first time. RESULTS: Red Dutch (a red Ribes rubrum cultivar) contained more malic acid but fewer sugars and had a lower sugar/acid ratio than Vertti (a green Ribes nigrum cultivar) and White Dutch (a white R. rubrum cultivar). Fructose (27–56 g L^?1 juice) and glucose (21–54 g L^?1) were the major sugars in all currant samples, but sucrose (7–20 g L^?1) was present only in Vertti. Vertti contained the most ascorbic acid. Sugars, malic acid and the sugar/acid ratio in Red Dutch were 11–28% higher in southern Finland than in northern Finland. The corresponding values in Vertti were 6–16% lower in the south than in the north, but no differences were found in White Dutch. As the relative humidity decreased, the amounts of citric acid and total acid increased in all cultivars, while the amount of sugars increased in Vertti but decreased in White Dutch and Red Dutch. In Red Dutch, high temperature and radiation levels increased the sugar content. CONCLUSION: The influence of latitude and weather conditions on qualitative parameters of currants varies with the cultivar. This study provides important guidance for currant cultivation and for further physiological and enzymological studies. Copyright © 2009 Society of Chemical Industry     

采用超临界参数的循环流化床

目前在波兰E lekrown ia Lagisza发电厂建造世界上第1座超临界蒸汽参数的循环流化床锅炉。该CFB锅炉的设计发电容量达460 MW,采用了西门子的本生垂直管(Benson Vertical)技术。该CFB锅炉预计在2006年投入运行。     

Quantitative analysis of phenolic compounds in Chinese hawthorn (Crataegus spp.) fruits by high performance liquid chromatography–electrospray ionisation mass spectrometry

Eleven major phenolic compounds (hyperoside, isoquercitrin, chlorogenic acid, ideain, epicatechin, two procyanidin (PA) dimers, three PA trimers and a PA dimer-hexoside) were quantified in the fruits of 22 cultivars/origins of three species of the Chinese hawthorn (Crataegus spp.) by HPLC–ESI-MS-SIR. Hyperoside (0.1–0.8 mg/g dry mass [DM]), isoquercitrin (0.1–0.3 mg/g DM), chlorogenic acid (0.2–1.6 mg/g DM), epicatechin (0.9–11.7 mg/g DM), PA B2 (0.7–12.4 mg/g DM), PA dimer II (0.1–1.5 mg/g DM), PA trimer I (0.1–2.7 mg/g DM), PA trimer II (0.7–6.9 mg/g DM), PA trimer III (0.01–1.2 mg/g DM) and a PA dimer-hexoside (trace–1.1 mg/g DM) were detected in all the samples. Ideain (0.0–0.7 mg/g DM) was found in all the samples except Crataegus scabrifolia. Significant correlations between the contents of individual PA aglycons were observed (r > 0.9, P < 0.01). A strong correlation between flavonols was also shown (r = 0.71, P < 0.01). Fruits of Crataegus pinnatifida var. major had higher contents of PAs but lower contents of flavonols compared with Crataegus brettschneideri. The fruits of C. scabrifolia contained the highest level of PA dimer-hexoside, which was present in trace amounts in the fruits of C. pinnatifida.     

Flow visualization inside a wire-plate electrostatic precipitator

A flow visualization study was performed in a wire-plate precipitator with a plate-plate spacing of 20.32 cm and wire-wire spacing of 20.32 cm. Smoke was used as the flow tracer, where injection and illumination were accomplished by two different techniques. In one method smoke was released from a single heated probe and illuminated by electronic flash. The other method employed a uniform smoke flow made visible by a laser sheet. The latter technique proved to be superior, providing well-defined views of the flow in both streamwise and spanwise planes over a wide range of velocities (0.2-2 m/s) and current densities (0-0.5 mA/m). The illuminated flow patterns were recorded by still 35 mm photography and color video taping. Of particular interest was the interaction between the precipitator gas flow and the corona-generated electric wind for both polarities of discharge. Results showed that positive corona discharge produces a stable two-dimensional smoke flow with negligible turbulent dispersion for precipitator velocities greater than 0.7 m/s. Lower velocities allowed the electric wind to dominate producing unstable, recirculating flow with widespread turbulence. Negative discharges were inherently unsteady and three-dimensional at all operating conditions but displayed extreme instability and recirculation (similar to positive polarity) for precipitator velocities less than 0.7 m/s     

Inter-organizational information systems adoption – a configuration analysis approach

In this article we propose a new complementary approach to investigate Inter-Organizational Information Systems (IOIS) adoption called configuration analysis. We motivate the need for a new approach by the common observation that the structure and the strategy of an IOIS are interdependent and that the IOIS adoptions consequently cluster orderly. For example, an IOIS setup with a powerful customer as a hub and many suppliers as spokes frequently surfaces across diffusion studies. Yet, this fact has not been integrated into existing analyses, and its implications have not been fully developed. We propose that IOIS scholars need to look beyond the single adopting organization in IOIS adoption studies and in contrast consider adoption units what we call an adoption configuration. Each such configuration can be further characterized along the following dimensions: (1) vision, (2) key functionality, (3) mode of interaction, (4) structure and (5) mode of appropriation. In addition, these dimensions do not co-vary independently. For example, a particular organizing vision assumes a specific inter-organizational structure. A typology of IOIS configurations for adoption analysis is laid out consisting of dyadic, hub and spoke, industry and community configurations. Specific forms or adoption analysis are suggested for each type of configuration. Overall, configuration analysis redirects IOIS adoption studies both at the theoretical and the methodological level, and a corresponding research agenda is sketched.     

Atomic force microscopy: influence of air drying and fixation on the morphology and viscoelasticity of cultured cells

The influence of fixation, air-drying and liquid-imaging on the morphology as well as on the viscoelasticity of malignant mesothelioma cells was studied by atomic force microscopy. In this study, dehydrated cells were more easily scanned and offered faster data recording than hydrated cells. However, the influence of fixation strength was more noticeable. Strong fixation induced flattening of the cytoplasm and loss of nuclear structure, resulting in a clearly visible cytoskeleton which could be easily seen as fibres orientated in the direction of the cell growth. By contrast, the morphology of hydrated cells was influenced to a lesser degree on fixation and showed an overall 'rounding' of the surface with vague, ill-defined structures. Nuclear areas of these samples were difficult to image.
Viscoelasticity measurements also exhibited large differences. Dehydrated cells were much harder and showed a uniform indentation profile over the whole cell that was independent of fixation. Indentation on hydrated cells was large and depended on the height of the measuring spot, the submembranous structure and, to a lesser extent, on fixation. To calculate an overall 'cellular' viscoelasticity, different methods were tested on these samples. Indentations of multiple, randomly chosen points, covering the whole cell, were measured and averaged to yield a mean indentation score. We avoided the thin and shadowed areas since it was shown that these regions were less suited for measuring. Using this design, large viscoelasticity differences were found, on which the influence of the external parameters could be shown. In another set-up, layered imaging was tried. However, long data acquisition times caused cellular activation and rearrangement, making this scanning mode unsatisfactory.     

The humidity buffer capacity of clay–sand plaster filled with phytomass from treatment wetlands

The aim of our study was to measure the amount of moisture absorption and desorption in clay–sand plaster mixed with “fibre-wool” from Typha spadixes and chips of Typha and Phragmites. Common cattail (Typha latifolia) and common reed (Phragmites australis) are the most common plants in constructed and semi-natural wetlands for wastewater treatment, as they are highly valued in ecologically oriented construction. The cattail and reed for the experiment were harvested in a wastewater treatment subsurface flow semi-natural wetland and in two free water surface constructed wetlands which showed reliable aboveground phytomass production over a 5 years period (for Typha, 0.37–1.76 kg DW m⁻² in autumn and 0.33–1.38 kg DW m⁻², and for Phragmites, 0.61–1.32 and 0.61–1.02 kg DW m⁻², respectively). The quantity of moisture absorption and desorption was measured in a climatic chamber where the humidity of ambient air was suddenly raised from 50% to 80% (absorption) and reduced from 80% to 50% (desorption). Over 12 h, all of the samples released the same amount of water as they absorbed. The clay–sand plaster samples absorbed slower than they desorbed, whereas the gypsum wallboard required significantly more time for desorption. Added phytomass gave positive effects by reducing the weight of the clay–sand plaster, accelerating and increasing moisture absorption.     

ANN modeling applied to NO x reduction with octane in a new microreactor

A silver/alumina catalyst was tested for its NO _x reduction activity during oxygen-rich conditions and during variation in the input parameters (nitric oxide, octane and oxygen). The experimental data using the microreactor was investigated by means of artificial neural networks (ANN).