Selecting Probability Distributions for Use in Complex Discrete Event Simulation Models

In discrete event simulation, probability distributions are used as models of various unpredictable system components. The times between equipment failures and job processing times are examples of such random system components. The commonly recommended and taught practice for selecting a probability distribution to represent a random component is a multistep process that concludes with a recommended “best fit” distribution. In this research, a more straightforward approach for selecting a probability distribution to represent a random component is examined. In this approach a standard or “default” distribution is used, with parameters set so that the distribution moments match the first two sample moments of collected data. Two default distributions were examined, which were the two parameter Lognormal, and Mixed Empirical-Exponential distribution. Comparisons of the use of default distributions was compared to the use of best fit distributions in three models of increasing complexity. Measurements of complexity were developed that show a clear difference in the complexity of the models developed. Statistically significant differences in estimated performance measures when using best, or default distributions are less frequent as the systems become more complex. The results also indicate that using two-parameter lognormal default distributions results in fewer differences when compared to results using best fit distributions than the Mixed Empirical-Exponential default distribution

Aerodynamic analysis of Speedo Fastskin-I Swimsuit

Swimming is one of the most energy intensive sporting events, where a winner is decided by a short margin. The winning time margin can be increased by various means, including engineered outfits within the game's regulations. In swimming, apart from optimisation of the swimmer's body, an appropriately devised swimsuit can play a significant role in reducing the drag, thereby enhancing the winning time margin. The main motivation for undertaking this study stems from the increasing levels of technical sophistication in the swimsuits that are claimed by the manufacturers for performance enhancement. Therefore, the goal of this paper is to undertake an experimental study with microscopic illustration of the swimsuit fabric, and its effects on aerodynamic properties. The study utilised a commercial swimsuit under stretched and un-stretched conditions of fabric morphology, and their impact on aerodynamic drag. This study was conducted using a wind tunnel for a range of Reynolds numbers. The simplified body shape was used to determine the aerodynamic drag. The finding of this study illustrates that there is a significant difference between the aerodynamic drag for the stretched and un-stretched surface morphology of the Speedo FS-I swimsuit. Furthermore, the microscopic analysis of the stretched and un-stretched fabric was undertaken to extend our undertstanding

Effect of a long bout versus short bouts of walking on weight loss during a weight loss diet: a randomized trial

Objective: To evaluate the effect of different daily physical activity (PA) frequencies while maintaining the same daily volume of PA on weight loss, carbohydrate and lipid metabolism, in women with overweight/obesity throughout a 24- week intervention.Methods: 65 women [BMI = 27- 35 kg/m²; age= 18-40 y] who had a sedentary lifestyle were randomly allocated to include either a longer-bout of PA (LBP), 50 min/d moderate-intensity PA, or two shorter-bouts of PA (SBP), two 25 min/d moderate intensity PA, 6 d/week during their weight loss plan. Anthropometric and blood measurements were taken at baseline and 24 weeks.Results: Compared with the LBP group, the SBP group had a greater decrease in weight (SBP: -8.08 ± 2.20 kg; LBP: -6.39 ± 2.28 kg; P = 0.019), BMI (SBP: -3.11 ± 0.87 kg/m²; LBP: -2.47 ± 0.86 kg/m², P=0.027) and waist circumference (SBP: -8.78 ± 2.62 cm; LBP: -5.76 ± 2.03 cm; P = 0.026). No significant differences were seen in carbohydrate and lipid metabolism characteristics after the 24 weeks.Conclusion: PA undertaken in 2 shorter-bouts per day could be more effective for weight loss than when undertaken in a daily long-bout in adult women on a 24 wk weight loss program

Peculiar behavior of the electrical resistivity of MnSi at the ferromagnetic phase transition

The electrical resistivity of a single crystal of MnSi was measured across its ferromagnetic phase transition line at ambient and high pressures. Sharp peaks of the temperature coefficient of resistivity characterize the transition line. Analysis of these data shows that at pressures to ~0.35 GPa these peaks have fine structure, revealing a shoulder at ~ 0.5 K above the peak. It is symptomatic that this structure disappears at pressures higher than ~0.35 GPa, which was identified earlier as a tricritical poin

Effects of mindfulness, reappraisal, and suppression on sad mood and cognitive resources

The present study investigated the relative effects of mindfulness, reappraisal and suppression in reducing sadness, and the extent to which implementation of these strategies affects cognitive resources in a laboratory context. A total of 171 Singaporean undergraduate participants were randomly assigned to receive brief training in mindfulness, reappraisal, or suppression prior to undergoing a sad mood induction. Individual adherence to Asian cultural values was assessed as a potential moderator of strategy effectiveness. Participants rated their mood and completed a Color-Word Stroop task before and after mood regulation instructions. Analyses using multi-level modelling showed that the suppression condition caused less robust declines in sadness over time compared to mindfulness. There was also a nonsignificant trend in which mindfulness was associated with greater sadness recovery compared to reappraisal. Suppression resulted in lower average sadness compared to mindfulness among those high on Asian cultural values, but not those low on Asian cultural values. Both mindfulness and reappraisal buffered against increases in Stroop interference from pre-to post-regulation compared to suppression. The findings highlight the advantage of mindfulness as a strategy effective not only in the regulation of sad mood, but also in the preservation of cognitive resources in the context of mood regulation

Psychological and neural mechanisms of trait mindfulness in reducing depression vulnerability

Mindfulness-based interventions are effective for reducing depressive symptoms. However, the psychological and neural mechanisms are unclear. This study examined which facets of trait mindfulness offer protection against negative bias and rumination, which are key risk factors for depression. Nineteen male volunteers completed a 2-day functional magnetic resonance imaging study. One day utilized a stress-induction task and the other day utilized a mindful breathing task. An emotional inhibition task was used to measure neural and behavioral changes related to state negative bias, defined by poorer performance in inhibiting negative relative to neutral stimuli. Associations among trait mindfulness [measured by the Five Facet Mindfulness Questionnaire (FFMQ)], trait rumination, and negative bias were examined. Non-reactivity scores on the FFMQ correlated negatively with rumination and negative bias following the stress induction. Non-reactivity was inversely correlated with insula activation during inhibition to negative stimuli after the mindful breathing task. Our results suggest non-reactivity to inner experience is the key facet of mindfulness that protects individuals from psychological risk for depression. Based on these results, mindfulness could reduce vulnerability to depression in at least two ways: (i) by buffering against trait rumination and negative bias and (ii) by reducing automatic emotional responding via the insula

Performance of Gonad Maturation and Spawned of Grouper Broodstock Cross Breeding Between F-2 and F-0

In fish grouper escpecially humpback grouper culture, seed and broodstock quality and availability determine the production success. Main supply of wild broodstock still dominates grouper hatchery activities, therefore, the exploitation of the wild broodstock is very high. Efforts to use the supply of cultured broodstock through selection and breeding processes will greatly determine their culture success. The purpose of this experiment was to get seeds from the cross breeding between F-2 and F-0. The research used two (2) concrete tanks with volume of 75 m3 each. Each tank was filled with 20 fishes consisting of 10 fishes of F-2 and 10 fishes of F-0. The experiment was conducted the Institute of Mariculture Research and Development, Gondol, Bali. The result showed a good gonadal development and natural spawning of cross breeding between F-2 and F-0. Total number of eggs (1.320.000) was found the highest in May in tank A, while the highest fertilized eggs of 385.000 were found in June. The SSCP analyses showed no difference in genetic characters of broodstock from cross-breeding between the female parent F-2 and F-0 male parent

Solar Assisted Heat Pump System for High Quality Drying Applications: A Critical Review

Solar assisted heat pump (SAHP) system integrates a solar thermal energy source with a heat pump. This technique is a very fundamental concept, especially for drying applications. By combining a solar thermal energy source such as solar thermal collectors and a heat pump dryer will assist in reducing the operation cost of drying and producing products with high quality. Many review papers in the literature evaluated the R&D aspects of solar-assisted heat pump dryers (SAHPD). This critical review paper studies some of the researches conducted in this field to understand and provides an update on recent developments in SAHPD. Also, a detailed explanation of principles and operation for SAHPD and its applications are presented. The used types of solar thermal collectors, as well as various heat pump dryers, are all discussed in this article. Finally, it is concluded that there is a clear lack of research in the techno-economic and environmental evaluation, while most of SAHPD studies focused on the performance study of the system

PRODUCTION OF FUNCTIONAL MALE BROODSTOCK OF CORAL TROUT GROUPER (Plectropomus leopardus)

Fertilization rate of the first generation of coral trout grouper, Plectropomus leopardus from wild broodstock in cultured tank was relatively low of 10-35%. Based on gonad histology analysis of 30 samples, only one male was found in early stage maturation. Therefore, it is needed to increase functional male production to ensure an increase level of egg fertilization. The experiment was conducted for 9 months using coral trout broodstock, from wild stock as control and selected F1 from culture as treatment. Broodstocks were reared in three tanks, each was 100 m3 in volume with 54 fishes/tank. All selected cultured fish (F1) in tank C were implanted with 17a-MT hormone at 50 mg/kg of body weight every month for 3 consecutive months. Wild stock fish in tank A and selected cultured fish (F1) in tank B were not implant as controls. The result showed that the number of male  increased 6 times in implanted by 17a-MT hormone compared to fish without implant only increased 2 times. Therefore, eggs fertilization and hatching rate were significantly increased by implanting F1 broodstocks with hormone17a-MT. Keywords: Functional male, broodstock, Coral trout (Plectropomus leopardus

Population density and territory size in juvenile rainbow trout, Oncorhynchus mykiss: implications for population regulation.

We manipulated population density of juvenile rainbow trout ( Oncorhynchus mykiss ) across a range of realistic densities in artificial stream channels, while controlling food abundance in two different ways: in Experiment 1, the total amount of food was held constant over a threefold increase in density, whereas in Experiment 2, the per capita amount of food was held constant over an eightfold increase in density. We tested the contrasting predictions that territory size (i) is not affected by population density; (ii) decreases with population density as 1/n, where n = the local population size; or (iii) decreases with population density but towards an asymptotic minimum size. In Experiment 1, territory size decreased with increasing population density. With the broader range of densities used in Experiment 2, territory size initially decreased with density and then leveled off at a minimum territory radius of 20–30 cm. Our results suggest an asymptotic minimum size of about 0.2 m2 for a 5 cm rainbow trout, similar to what is observed for high-density conditions in the wild. This minimum territory size could potentially set an upper limit on local population density and help regulate the population size of stream salmonids. </jats:p