The Effect of Applying Design of Experiments Techniques to Software Performance Testing

Effective software performance testing is essential to the development and delivery of quality software products. Many software testing investigations have reported software performance testing improvements, but few have quantitatively validated measurable software testing performance improvements across an aggregate of studies. This study addressed that gap by conducting a meta-analysis to assess the relationship between applying Design of Experiments (DOE) techniques in the software testing process and the reported software performance testing improvements. Software performance testing theories and DOE techniques composed the theoretical framework for this study. Software testing studies (n = 96) were analyzed, where half had DOE techniques applied and the other half did not. Five research hypotheses were tested, where findings were measured in (a) the number of detected defects, (b) the rate of defect detection, (c) the phase in which the defect was detected, (d) the total number of hours it took to complete the testing, and (e) an overall hypothesis which included all measurements for all findings. The data were analyzed by first computing standard difference in means effect sizes, then through the Z test, the Q test, and the t test in statistical comparisons. Results of the meta-analysis showed that applying DOE techniques in the software testing process improved software performance testing (p \u3c 05). These results have social implications for the software testing industry and software testing professionals, providing another empirically-validated testing methodology. Software organizations can use this methodology to differentiate their software testing process, to create more quality products, and to benefit the consumer and society in general

Designs and Technology Requirements for Civil Heavy Lift Rotorcraft

The NASA Heavy Lift Rotorcraft Systems Investigation examined in depth several rotorcraft configurations for large civil transport, designed to meet the technology goals of the NASA Vehicle Systems Program. The investigation identified the Large Civil Tiltrotor as the configuration with the best potential to meet the technology goals. The design presented was economically competitive, with the potential for substantial impact on the air transportation system. The keys to achieving a competitive aircraft were low drag airframe and low disk loading rotors; structural weight reduction, for both airframe and rotors; drive system weight reduction; improved engine efficiency; low maintenance design; and manufacturing cost comparable to fixed-wing aircraft. Risk reduction plans were developed to provide the strategic direction to support a heavy-lift rotorcraft development. The following high risk areas were identified for heavy lift rotorcraft: high torque, light weight drive system; high performance, structurally efficient rotor/wing system; low noise aircraft; and super-integrated vehicle management system

Navier-Stokes Calculations for a Highly-Twisted Rotor Near Stall

The viscous flow field near the surface of a hovering rotor blade was studied for blade twist distributions typical of a till rotor blade and a conventional helicopter rotor blade. Three blade geometries were studied, including a tilt rotor blade twist distribution (baseline), conventional helicopter rotor blade twist distribution, and the baseline twist distribution with 2 deg of precone. The results give insight into the delayed stall phenomenon often observed for highly twisted rotors. Calculations were performed for a high thrust condition near stall using the thin-layer Navier-Stokes CFD code TURNS. Effects of built-in twist on section force coefficients, skin friction, velocities, surface pressures, and boundary layer shape factor are discussed. Although the rotor thrust coefficient was nominally the same for the cases using the two twist distributions, large differences were found in the section in-plane and normal force coefficients. These preliminary results imply that the blade outboard region, rather than the inboard region, provides the majority of the performance advantage of the baseline case over the low twist case. Skin friction, velocities near the blade, and surface pressures for the two twist distributions reveal significant differences in the blade outboard region

NASA Heavy Lift Rotorcraft Systems Investigation

The NASA Heavy Lift Rotorcraft Systems Investigation examined in depth several rotorcraft configurations for large civil transport, designed to meet the technology goals of the NASA Vehicle Systems Program. The investigation identified the Large Civil Tiltrotor as the configuration with the best potential to meet the technology goals. The design presented was economically competitive, with the potential for substantial impact on the air transportation system. The keys to achieving a competitive aircraft were low drag airframe and low disk loading rotors; structural weight reduction, for both airframe and rotors; drive system weight reduction; improved engine efficiency; low maintenance design; and manufacturing cost comparable to fixed-wing aircraft. Risk reduction plans were developed to provide the strategic direction to support a heavy-lift rotorcraft development. The following high risk areas were identified for heavy lift rotorcraft: high torque, light weight drive system; high performance, structurally efficient rotor/wing system; low noise aircraft; and super-integrated vehicle management system

Phytochemical screening, antioxidant, antiulcer and toxicity studies on Desmodium adscendens (Sw) DC Fabaceae leaf and stem

Purpose: To assess the phytochemical profile, toxicity, as well as the antioxidant, and antiulcer activities of the methanol extracts of Desmodium adscendens stem and leaf.Methods: Maceration procedure was employed in the preparation of the methanol extracts. Phytochemical characterization of the extracts was carried out according to standard methods. In vitro antioxidant activity was evaluated using 2, 2-diphenyl-1-picryhyldrazy (DPPH l) and ferric reducing antioxidant power assay (FRAP). Antiulcer activity was investigated using ethanol-induced ulcer model, while toxicity was assessed by observing the mice for mortality.Results: Phytochemical analysis indicate the presence of glycosides, alkaloids, tannins, flavonoids, and saponins in the stem and leaf. Methanol extracts of the plant exhibited antioxidant activity, with DPPH assay results showing median inhibitory concentration (IC50) of 87.59 (leaf), 108.87 (stem), 28.52 (alpha-tocopherol), and 5.05 μg/mL (ascorbic acid). The FRAP assay results for the stem and leaf extracts were 1483 and 1953 μM Fe2+/g dry plant, respectively, while for ascorbic acid it was 3463 μMFe2+/g. The extracts showed significant antiulcer activity, with 14.27 and 15.18 % ulceration inhibition for the leaf extract, and 12.31 and 13.36 % for the stem extract at administered doses of 100 and 200 mg/kg, respectively. Cimetidine and omeprazole (standards) showed ulceration inhibition of 5.53, and 8.26 % at 5.7 and 0.57 mg/kg doses, respectively.Conclusion: The methanol extracts of Desmodium adscendens stem and leaf offer significant protective activity against ethanol-induced gastric ulceration in rats, and the activity may be related to their antioxidant effect.Keywords: Antioxidant, Antiulcer, Toxicity, Desmodium adscenden

Reducing the Incidence of Skin Breakdown in the Surgical Patient

https://digitalcommons.psjhealth.org/stvincent-bootcamp/1028/thumbnail.jp

Decay of metastable phases in a model for the catalytic oxidation of CO

We study by kinetic Monte Carlo simulations the dynamic behavior of a Ziff-Gulari-Barshad model with CO desorption for the reaction CO + O $\to$ CO$_2$ on a catalytic surface. Finite-size scaling analysis of the fluctuations and the fourth-order order-parameter cumulant show that below a critical CO desorption rate, the model exhibits a nonequilibrium first-order phase transition between low and high CO coverage phases. We calculate several points on the coexistence curve. We also measure the metastable lifetimes associated with the transition from the low CO coverage phase to the high CO coverage phase, and {\it vice versa}. Our results indicate that the transition process follows a mechanism very similar to the decay of metastable phases associated with {\it equilibrium} first-order phase transitions and can be described by the classic Kolmogorov-Johnson-Mehl-Avrami theory of phase transformation by nucleation and growth. In the present case, the desorption parameter plays the role of temperature, and the distance to the coexistence curve plays the role of an external field or supersaturation. We identify two distinct regimes, depending on whether the system is far from or close to the coexistence curve, in which the statistical properties and the system-size dependence of the lifetimes are different, corresponding to multidroplet or single-droplet decay, respectively. The crossover between the two regimes approaches the coexistence curve logarithmically with system size, analogous to the behavior of the crossover between multidroplet and single-droplet metastable decay near an equilibrium first-order phase transition.Comment: 27 pages, 22 figures, accepted by Physical Review

Using risk-ranking of metals to identify which poses the greatest threat to freshwater organisms in the UK

Freshwater aquatic organisms face the challenge of being exposed to a multitude of chemicals discharged by the human population. The objective of this study was to rank metals according to the threat they pose to aquatic organisms. This will contribute to a wider Chemical Strategy for freshwater which will risk rank all chemicals based on their potential risk to wildlife in a UK setting. The method involved comparing information on ecotoxicological thresholds with measured concentrations in rivers. The bioconcentration factor was also considered as a ranking method. The metals; Ag, Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn, were analysed using this approach. Triclosan and lindane were used as comparative organic pollutants. Using a range of ranking techniques, Cu, Al and Zn came top of the list of concern, with Cu coming first

Cyanobacteria and microcystin contamination in untreated and treated drinking water in Ghana

© 2017, Page Press Publications. All rights reserved. Although cyanobacterial blooms and cyanotoxins represent a worldwide-occurring phenomenon, there are large differences among different countries in cyanotoxin-related human health risk assessment, management practices and policies. While national standards, guideline values and detailed regulatory frameworks for effective management of cyanotoxin risks have been implemented in many in­dustrialized countries, the extent of cyanobacteria occurrence and cyanotoxin contamination in certain geographical regions is underreported and not very well understood. Such regions include major parts of tropical West and Central Africa, a region constisting of more than 25 countries occupying an area of 12 million km2, with a total population of 500 milion people. Only few studies focusing on cyanotoxin occurrence in this region have been published so far, and reports dealing specifically with cyanotoxin contamination in drinking water are extremely scarce. In this study, we report seasonal data on cyanobactcria and microcystin (MC) contamination in drinking water reservoirs and adjacent treatment plants located in Ghana, West Africa. During January-June 2005, concentrations of MCs were monitored in four treatment plants supplying drinking water to major metropolitan areas in Ghana: the treatment plants Barekese and Owabi, which serve Kumasi Metropolitan Area, and the plants Kpong and Weija, providing water for Accra-Tema Metropolitan Area. HPLC analyses showed that 65% samples of raw water at the intake of the treatment plants contained intracellular MCs (maximal detected concentration was 8.73 fig L-1), whereas dissolved toxins were detected in 33% of the samples. Significant reduction of cyanobacterial cell counts and MC concentrations was achieved during the entire monitoring period by the applied conventional water treatment methods (alum flocculation, sedimentation, rapid sand filtration and chlorination), and MC concentration in the final treated water never exceeded 1 fig L-1 (WHO guideline limit for MC-LR in drinking water). However, cyanobacterial cells (93-3,055 cell mL-1) were frequently found in the final treated water and intracellular MCs were detected in 17% of the samples (maximal concentration 0.61 (μg L-1), while dissolved MCs were present in 14% of the final treated water samples (maximal concentration 0.81 μg L-1). It indicates a borderline efficiency of the water treatment, thus MC concentrations in drinking water might exceed the WHO guideline limit if the treatment efficiency gets compromised. In addition, MC concentrations found in the raw water might represent significant human health risks for people living in areas with only a limited access to the treated or underground drinking water

Proposing an Engineering Gendered Racial Microaggression Scale

Background Minorities in engineering regularly experience negative statements or behaviors of others that disparage them due to their gender, race, ethnicity, or other identity. Students from engineering have cited these persistent subtle negative statements and behaviors, or microaggressions, as reasons for considering leaving engineering programs or the university entirely. Previous measures of microaggressions have not been designed to capture the unique experiences of minorities within the engineering environment. Purpose This research differs from previous work because it incorporates an intersectional perspective by acknowledging microaggressions are not experienced universally for individuals within all groups or institutions (Crenshaw et al. 1993; Wilkins 2012). In the context of a predominantly white institution (PWI) and a historically black college/university (HBCU), the experiences of gender and racial minorities in engineering departments were asked to share their experiences to identify overarching themes in microaggressive language and actions. The research strives to answer, “How do gender and race microaggressions affect student success and persistence in engineering programs?” Brief Research Methodology and Approach The preliminary scale used a three phased approach to scaled design to nest the novel scale in the existing literature, previous scales, and from interviews with minority engineering undergraduate students. The current paper presents a preliminary Engineering Gender and Racial Microaggression Scale (EGRMS) to measure microaggressions within the engineering environment. Preliminary Results This research expands knowledge on intersectional microaggression experiences of engineering students. The overarching goal is to address the needs of multiple identity groups including the dominant white male student, female students, and students of color