scholarly journals Performance Evaluation of an Object Management Policy Approach for P2P Networks

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Dario Vieira ◽  
Cesar A. V. Melo ◽  
Yacine Ghamri-Doudane
Keyword(s):  
Large Scale ◽  
Scalable Video Coding ◽  
Experimental Studies ◽  
Management Policy ◽  
P2p Systems ◽  
Object Management ◽  
Web Cache ◽  
High Scalability ◽  
Management Policies ◽  
The Impact

The increasing popularity of network-based multimedia applications poses many challenges for content providers to supply efficient and scalable services. Peer-to-peer (P2P) systems have been shown to be a promising approach to provide large-scale video services over the Internet since, by nature, these systems show high scalability and robustness. In this paper, we propose and analyze an object management policy approach for video web cache in a P2P context, taking advantage of object's metadata, for example, video popularity, and object's encoding techniques, for example, scalable video coding (SVC). We carry out trace-driven simulations so as to evaluate the performance of our approach and compare it against traditional object management policy approaches. In addition, we study as well the impact of churn on our approach and on other object management policies that implement different caching strategies. A YouTube video collection which records over 1.6 million video's log was used in our experimental studies. The experiment results have showed that our proposed approach can improve the performance of the cache substantially. Moreover, we have found that neither the simply enlargement of peers' storage capacity nor a zero replicating strategy is effective actions to improve performance of an object management policy.

scholarly journals Clinical Investigations of the Effect of Citrus unshiu Peel Pellet on Obesity and Lipid Profile

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Seongil Kang ◽  
Sangyeol Song ◽  
Joosang Lee ◽  
Hyekyung Chang ◽  
Sanghun Lee
Keyword(s):  
Lipid Profile ◽  
Total Cholesterol ◽  
Cholesterol Level ◽  
Weight Control ◽  
Large Scale ◽  
Total Cholesterol Level ◽  
Experimental Studies ◽  
Density Lipoprotein ◽  
Citrus Unshiu ◽  
The Impact

Objectives. Several experimental studies have reported antiobesity and lipid-improving effects of Citrus unshiu. However, clinical studies on its effects are lacking. This study was designed to evaluate the impact of Citrus unshiu peel pellet (CUPP) on obesity and lipid profile. Methods. For 118 patients with body mass index (BMI) > 23 who took Citrus unshiu peel pellet (CUPP) for 4 weeks in a Public Health Center, laboratory and biometric readings before and after CUPP administration were analyzed. Results. Mean age of these subjects was 53.8±10.6 years (range: 18-75 years). There were 88 (74.6%) females in the study sample (n = 118). A significant (p < 0.01) decrease in BMI from 27.47±2.24 to 27.27±2.22 was observed in all subjects after CUPP treatment and 65.3% (N = 77) of them lost 1.03±0.83 kg of weight after 4 weeks of treatment. Total cholesterol level was significantly (p < 0.01) decreased from 204.0±37.4 mg/dL to 193.5±36.5 mg/dL. Significant (p < 0.05) decreases in levels of low-density lipoprotein, cholesterol, and triglyceride were also observed. Conclusions. These results suggest that CUPP in practice could help weight control and improve total cholesterol level. Findings of this study provide clinical foundation for future large-scale trials to establish clinical benefits of CUPP.

Experimental Indirect Determination of Wind Turbine Performance and Blade Element Theory Parameters in Controlled Conditions

2012 ◽  
Vol 36 (6) ◽  
pp. 717-737 ◽  
Author(s):  
David A. Johnson ◽  
Ahmed Abdelrahman ◽  
Drew Gertz
Keyword(s):  
Large Scale ◽  
Radial Direction ◽  
Turbine Blades ◽  
Model Development ◽  
Experimental Studies ◽  
Indirect Determination ◽  
Controlled Conditions ◽  
Power Measurements ◽  
The Impact ◽  
Blade Element

The performance of a three bladed 3.3 m diameter turbine was measured unobtrusively in a large scale, controlled wind, open jet facility. Due to the scale of the facility blockage was very low in comparison to previous studies. The turbine blades utilized NREL S83X airfoils appropriate for the flow conditions and Reynolds number present in the facility. Airfoils were blended along the radial direction in a varying chord, varying twist blade design with a design coefficient of power ( Cp) peak at λ = 5.4. Simultaneous three component velocity measurements were obtained using a purpose built traverse at specific radial locations (segments) upstream and immediately downstream of the rotor plane. These velocities were utilized to determine blade element momentum (BEM) parameters and to predict the performance of the rotor. Comparisons are made to the limited number of experimental studies reported in the literature and with parameters derived from CFD numerical simulations. Measured radial velocities upstream of the rotor were near zero and uniform in the radial direction and were uniform and slightly larger downstream of the rotor indicating the BEM assumption of limited radial interaction between segments was acceptable and that the wake was expanding. Axial induction was most uniform in the radial direction at the design and peak Cp condition and area averaged values approached 1/3 but did not exceed this value. Tangential measured velocities, tangential induction and circulation show the impact of the nacelle and blade root location and the tip. An evaluation of the local angle of attack and two dimensional airfoil data at one radial location gave a reasonable comparison with other measured torque values. Rotor performance determined with this method was compared with electrical power measurements and previous BEM model predictions. The power derived from the BEM method outlined here closely followed electrical turbine power measurements although the method overpredicted the power likely due to the segment discretization in the tip region. The detail of these results should be useful to further understand the flow immediately downstream of a rotor in controlled conditions and provide detailed data for BEM model enhancement and future model development.

scholarly journals The Impact of Forest Management Restrictions on Aspen Harvest Levels and Forest Structure in Itasca County, Minnesota

1999 ◽  
Vol 16 (4) ◽  
pp. 177-184
Author(s):  
Joan M. Nichols ◽  
Dietmar W. Rose ◽  
Syed A. Husain
Keyword(s):  
Forest Structure ◽  
Management Policy ◽  
Forest Composition ◽  
Timber Supply ◽  
Trade Offs ◽  
Long Run ◽  
Spatial Attributes ◽  
Management Policies ◽  
The Impact ◽  
Selection Of

Abstract Potential management policies of the Minnesota Department of Natural Resources (MDNR) designed to enhance nontimber values were examined to estimate their impact on permissible harvest levels, forest composition and spatial attributes of aspen in Itasca County, Minnesota. An allowable cut equal to the Long Run Sustained Yield (LRSY) was estimated and used as the target harvest level for each management policy. Results were analyzed in a number of ways including Geographic Information Systems (GIS). The study illustrates that the selection of specific management policies can have significant impacts on timber supply as well as forest structures. Therefore, any suggested policy should always be reviewed for its potential impacts and associated trade-offs before implementation. North. J. Appl. For. 16(4):177-184.

Assessing young learners’ foreign language abilities

2020 ◽  
Vol 54 (1) ◽  
pp. 1-37 ◽  
Author(s):  
Marianne Nikolov ◽  
Veronika Timpe-Laughlin
Keyword(s):  
Foreign Language ◽  
Language Learning ◽  
Language Proficiency ◽  
Large Scale ◽  
Experimental Studies ◽  
Language Abilities ◽  
Language Programs ◽  
Young Learners ◽  
Foreign Language Programs ◽  
The Impact

AbstractGiven the exponential growth in the popularity of early foreign language programs, coupled with an emphasis of evidence-based instruction, assessing young learners’ (YLs) foreign language abilities has moved to center stage. This article canvasses how the field of assessing young learners of foreign languages has evolved over the past two decades. The review offers insights into how and why the field has developed, how constructs have been defined and operationalized, what language proficiency frameworks have been used, why children were assessed, what aspects of their foreign language proficiency have been assessed, who was involved in the assessment, and how the results have been used. By surveying trends in foreign language (FL) and content-based language learning programs involving children between the ages of 3 and 14, the article highlights research into assessment of and for learning, and critically discusses areas such as large-scale assessments and proficiency examinations, comparative and experimental studies, the impact of assessment, teachers’ beliefs and assessment practices, young learners’ test-taking strategies, age-appropriate tasks, alternative and technology-mediated assessment, as well as game-based assessments. The final section of the article highlights where more research is needed, thus outlining potential future directions for the field.

scholarly journals Economic and Mathematical Modeling of the Direct Effects of Large-Scale Infrastructure Projects on Developing Territories

2019 ◽  
pp. 78-89
Author(s):  
Olga Patrakeeva
Keyword(s):  
Economic Growth ◽  
Simulation Model ◽  
Large Scale ◽  
System Analysis ◽  
Distribution Functions ◽  
Management Policy ◽  
Infrastructure Projects ◽  
Railway Transport ◽  
Krasnodar Krai ◽  
The Impact

The problem of assessing the effects of infrastructure projects for territories is debatable. Modeling experience has been accumulated today, and elaborated macroeconomic models allow to identify causal relationships between the indicators of transport development and economic growth. The goal of this article is to define a simulation model of assessing the impact of transport projects on the economic growth of Krasnodar Krai exemplified by the Crimean Bridge project. The solution of this scientific problem requires taking into account different factors and complicated interrelationships within the framework of the regional social and economic system under consideration, using methods of system analysis and tools of economic and mathematical simulation. The simulation model reflects the scenario parameters of the capital management policy, highway transport freight turnover, highway transport freight turnover directly connected with the construction of Kerch Straight Bridge, carriage of goods by railway transport, carriage of goods by railway transport directly connected with the construction of Kerch Straight Bridge. The interrelations of this model’s parameters are established by the econometrics methods. In accordance with the produced scenarios the expected median values of the additional increment of the Krasnodar Krai GRP due to the increment of transportation associated with the Crimean Bridge operation are in the range between 0.97 % and 1.1 %. The most conservative scenario presumes the median value of 0.97 % and lower limit of 0.8 %. This tool can be used to assess the direct effect of railway and road construction for other Russian regions. The proposed simulation model will be further expanded by including further distribution functions of scenario variables and additional structural relationships.

scholarly journals The Effect of Youth Entrepreneurship Education Programs: Two Large-Scale Experimental Studies

SAGE Open ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 215824402095697
Author(s):  
Gayoung Kim ◽  
Dohyeon Kim ◽  
Woo Jin Lee ◽  
Sunyoung Joung
Keyword(s):  
Large Scale ◽  
Experimental Studies ◽  
Entrepreneurship Education ◽  
Entrepreneurial Intention ◽  
Social Problem Solving ◽  
Entrepreneurial Intentions ◽  
Comparison Groups ◽  
Quasi Experimental ◽  
Matched Comparison ◽  
The Impact

Recent years have witnessed the worldwide growth of entrepreneurship education (EE) as entrepreneurship is regarded as the key driver of innovation and economic growth. Most extant studies on EE have focused on its impact on entrepreneurial intentions. However, the application of the same EE measurements for both adults and adolescents has long been criticized; the indices developed for potential adult entrepreneurs may not be suitable for young entrepreneurs, considering the large time gap before they enter the workforce. This study aims to develop appropriate indicators for the assessment of youth EE in Korea and to examine the effectiveness of youth EE. Two large-scale quasi-experimental studies were conducted with pre- and posttest matched-comparison groups for verification. This study suggests six common variables for measuring the impact of youth EE: opportunity discovery, opportunity exploitation, entrepreneurship, creativity capacity, social problem solving, and entrepreneurial intention. The analyses showed that all these indicators positively influenced youth EE. We also proposed practical suggestions for the development of EE programs.

scholarly journals A numerical model for the time-dependent wake of a pedalling cyclist

2019 ◽  
Vol 233 (4) ◽  
pp. 514-525
Author(s):  
Martin D Griffith ◽  
Timothy N Crouch ◽  
David Burton ◽  
John Sheridan ◽  
Nicholas AT Brown ◽  
...  
Keyword(s):  
Drag Force ◽  
Large Scale ◽  
Aerodynamic Drag ◽  
Experimental Studies ◽  
Wake Flow ◽  
Time Dependent ◽  
Navier Stokes ◽  
Streamwise Vorticity ◽  
Leg Cycling ◽  
The Impact

A method for computing the wake of a pedalling cyclist is detailed and assessed through comparison with experimental studies. The large-scale time-dependent turbulent flow is simulated using the Scale Adaptive Simulation approach based on the Shear Stress Transport Reynolds-averaged Navier–Stokes model. Importantly, the motion of the legs is modelled by joining the model at the hips and knees and imposing solid body rotation and translation to the lower and upper legs. Rapid distortion of the cyclist geometry during pedalling requires frequent interpolation of the flow solution onto new meshes. The impact of numerical errors, that are inherent to this remeshing technique, on the computed aerodynamic drag force is assessed. The dynamic leg simulation was successful in reproducing the oscillation in the drag force experienced by a rider over the pedalling cycle that results from variations in the large-scale wake flow structure. Aerodynamic drag and streamwise vorticity fields obtained for both static and dynamic leg simulations are compared with similar experimental results across the crank cycle. The new technique presented here for simulating pedalling leg cycling flows offers one pathway for improving the assessment of cycling aerodynamic performance compared to using isolated static leg simulations alone, a practice common in optimising the aerodynamics of cyclists through computational fluid dynamics.

Improving turbine endwall cooling uniformity by controlling near-wall secondary flows

2016 ◽  
Vol 231 (14) ◽  
pp. 2689-2705 ◽  
Author(s):  
Mitra Thomas ◽  
Thomas Povey
Keyword(s):  
Mass Flux ◽  
Large Scale ◽  
Guide Vane ◽  
Pressure Ratio ◽  
Experimental Studies ◽  
Pressure Profile ◽  
Design Guidelines ◽  
Secondary Flows ◽  
The Impact ◽  
Endwall Cooling

In this paper, we propose a design philosophy for cooling high-pressure nozzle guide vane endwalls, which exploits the momentum of cooling jets to control vane secondary flows thereby improving endwall cooling uniformity. The impact of coolant-to-mainstream pressure ratio, hole inclination angle, hole diameter, vane potential field, and overall mass flux ratios are considered. Arguments are developed by examining detailed experimental studies conducted in a large-scale low-speed cascade tunnel with engine-realistic combustor geometry and turbulence profiles. Computational fluid dynamics predictions validated by the same are used to extend the parameter space. We show that the global flow field is highly sensitive to the inlet total pressure profile, which in turn can be modified by introducing relatively low mass flow rates of cooling gas at engine realistic coolant-to-mainstream pressure ratios and mass flux ratios. This interaction effect must be understood for successful design of optimised endwall cooling schemes, an effect which is not sufficiently emphasized in much of the literature on this topic. Design guidelines are given that we hope will be of use in industry.

scholarly journals Overview of the fire management policy of the Kruger National Park

Koedoe ◽  
1999 ◽  
Vol 42 (1) ◽  
Author(s):  
H.C. Biggs ◽  
A.L.F. Potgieter
Keyword(s):  
National Park ◽  
Large Scale ◽  
Fire Management ◽  
Major Change ◽  
Management Plan ◽  
Kruger National Park ◽  
Management Policy ◽  
Fire Policy ◽  
Trade Offs ◽  
The Impact

New developments in fire management policy in the Kruger National Park are sketched against the background of changing attitudes towards ecosystem management. The experimental burning plots established in the mid-1950s are discussed briefly, as is the almost forty-year era of rotational block- burning. The lightning-driven fire policy initiated in 1992 and currently aimed at by park management is discussed, with comments on its early performance. More recent revision of the management plan stressed maximisation of appropriate research benefits from the experimental burning plots, con- doned the lightning approach for the present, but stressed the absolute necessity of the park not finding itself in the 1992 position again, where a major change in policy has to be made with no comparative evidence from other systems. To this end, a major landscape-scale fire management trial has been planned for implementation starting in April 2000. It is sheduled to run over a twenty-year period, and will be placed at four localities representing different major landscapes in the park. It will compare the effects of three different fire systems (lightning, patch mosaic, and range condition burning systems) on biodiversity elements crucial to the park's mission. The rationale for, layout of, and criteria for deciding on the outcome of the trial are discussed, as well as the trade-offs that were made to enable the trial to be of such a large scale and still fit into overall park planning. The impact of the trial on the park's monitoring programme is discussed.

scholarly journals Experimental studies on the hybrid system of heat and cold production from solar energy

2017 ◽  
Vol 21 (6 Part B) ◽  
pp. 2827-2835
Author(s):  
Stanislaw Gil ◽  
Boguslaw Gradon ◽  
Wojciech Bialik
Keyword(s):  
Solar Energy ◽  
Large Scale ◽  
Cooling System ◽  
Renewable Energy Sources ◽  
Experimental Studies ◽  
Hot Water ◽  
Temperate Climate ◽  
Water Tank ◽  
Energy Potential ◽  
The Impact

In recent years more and more energy is consumed in the European Union countries for summer air conditioning in buildings. This consumption will probably increase even more due to the predicted climate warming and the desire to improve the quality of life. At present final energy as heat and electricity is sourced mainly from fossil fuels. However, recently alternative renewable energy sources are increasingly taken into account as a result of efforts toward environmental protection and fuels savings. This paper presents results of the analysis of a hybrid solar-assisted heating and cooling system for buildings in the temperate climate of west and central Europe. Solar energy potential was estimated. The investigation was performed using a large scale laboratory installation, which contains an evacuated solar collector, a single-stage NH3-H2O absorption chiller and a hot water tank. The impact of the main system parameters on its performance was analyzed on the basis of energy balances.

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