computer simulation

摘要： Fixed-station sampling design was widely used in fishery-independent surveys because of its characteristics of convenient sampling station setting,but the non-probabilistic(fixed)nature made it more uncertainty of drawing inferences on population.The performance of fixed-station sampling design for multispecies survey has not been evaluated,and we are uncertain if the design could detect the temporal trends of different populations in multispecies fishery-independent survey.In this study,spatial distribution of abundance indices for three species with different spatial distribution patterns including small yellow croaker(Larimichthys polyactis),whitespotted conger(Conger myriaster)and Fang’s blenny(Enedrias fangi)were simulated using ordinary kriging interpolation as the“true”population distribution.The performance of fixed-station sampling design was compared with simple random sampling design by resampling the simulated“true”populations in this simulation study.The results showed that the fixed-station sampling design had the power to detect the seasonal trends of species abundance.The effectiveness of fixed-station sampling design were different in different species distribution patterns.When the species had even distribution,fixed-station sampling design could get high quality abundance data;when the distribution was uneven with heterogeneity or patchiness,fixed-station sampling design tended to underestimate or overestimate the abundance.Evidently,the estimates of abundance index based on the fixedstation sampling design must be calibrated cautiously while applying them for fisheries stock assessment and management.This study suggested that fixed-station sampling design could catch the temporal dynamics of population abundance,but the abundance estimates from the fixed-station sampling design could not be treated as the absolute estimates of populations.

摘要： The influences of rocker shoes on foot biomechanics were controversial because the interaction between two design factors—rocker angle and apex location,was usually omitted.This study investigated the interaction effects of rocker angle and apex location on plantar foot pressure,metatarsophalangeal/ankle angle,and Achilles tendon force during walking.Ten participants performed walking trials under six rocker shoe conditions:2 rocker angles(mild and severe)×3 apex locations(distal,standard,and proximal),wherein the plantar foot pressure was measured and the movement data were processed by musculoskeletal modeling to report joint angle and Achilles tendon force.A two-way ANOVA repeated measures was used for statistics.Significant interaction effects were reported in examinations of forefoot pressure,midfoot pressure,and metatarsophalangeal dorsiflexion.The standard apex significantly reduced peak forefoot and midfoot pressures(p=0.008–0.034,Hedges'g=0.75–0.84),which was further decreased by a severe rocker angle(p=0.006,Hedges'g=0.51–0.81).Moving the apex proximally reduced Achilles tendon forces(p<0.001,Hedges'g=0.80)and facilitated both metatarsophalangeal dorsiflexion and ankle plantarflexion during push-off(p=0.003–0.006,Hedges'g=0.03–0.82).Rocker angle seemed to have fewer effects on ankle joint angle and Achilles tendon force.We concluded that apex location was likely the dominant design factor of the rocker sole in influencing foot biomechanics,yet its interactions with rocker angle should be considered.The configuration of the two features could be varied to possess different therapeutic merits and adapt to specific application purposes.

摘要： Contemporary office buildings have been calling attention for intense use of glass on their façades.This way,glazed areas in such buildings may favor the access to natural light and contribute to power generation through photovoltaic systems.However,the application of STPV(Semi-Transparent Photovoltaic)may interfere with the building’s energy performance and good use of daylight.So,this work aims to assess daylighting and thermoenergetic performances in an office room located in southern Brazil,with different types of STPV applied to the building’s glasses.This study was carried out through computer simulation,integrating software’s Rhinoceros with DIVA plugin and EnergyPlus.Results have shown that the application of STPV with proper transparency percentage provides access to daylighting and increases visual comfort for occupants,and also contributes to the building’s energy balance,as it may save from 9.6%to 28%in energy.Its use,in the climatic context analyzed,has boosted energy consumption for cooling and for artificial lighting;however,photovoltaic generation was higher and thus compensated for the increase caused by the system.

摘要： Natural gas hydrate inhibitor has been serving the oil and gas industry for many years. The development and search for new inhibitors remain the focus of research. In this study, the solution polymerization method was employed to prepare poly(N-vinyl caprolactam-co-butyl methacrylate)(P(VCap-BMA)), as a new kinetic hydrate inhibitor(KHI). The inhibition properties of P(VCap-BMA) were investigated by tetrahydrofuran(THF) hydrate testing and natural gas hydrate forming and compared with the commercial KHIs. The experiment showed that PVCap performed better than copolymer P(VCap-BMA). However,low doses of methanol or ethylene glycol are compounded with KHIs. The compounding inhibitors show a synergistic inhibitory effect. More interesting is the P(VCap-BMA)-methanol system has a better inhibitory effect than the PVCap-methanol system. 1% P(VCap-BMA) + 5% methanol presented the best inhibiting performance at subcooling 10.3 °C, the induction time of natural gas hydrate was 445 min.Finally, the interaction between water and several dimeric inhibitors compared by natural bond orbital(NBO) analyses and density functional theory(DFT) indicated that inhibitor molecules were able to form the hydrogen bond with the water molecules, which result in gas hydrate inhibition. These exciting properties make the P(VCap-BMA) compound hydrate inhibitor promising candidates for numerous applications in the petrochemical industry.

摘要： The basic assumption of an energy-efficient project is the proper relation with the local climatic context.To analyse a building’s performance before its construction,it is necessary that the object to be designed is recreated in a virtual environment,to evaluate its thermal balance.In order to recreate this virtual environment,it is necessary to use computer programs,and that requires a file composed of a weather database organized hourly in a specific year and defined,in the case of this article,from a TRY(test reference year).The objective of this study is to prepare a weather file for the city of Pelotas,RS,Brazil.This research was structured in five stages.In the first stage,the TRY was determined.In the second stage,the necessary variables for the preparation of the weather file to be used in the programs EnergyPlus?and Design Builder?were created and treated.In the third stage,weather files were prepared in.epw and.try formats.In the fourth stage,the weather file generated was simulated and compared with two other weather files belonging to the same bioclimatic zone.In the fifth and last stage,a typical day was elaborated for the city of Pelotas.As a result,the importance of optimization of the EPW generation process based on algorithms was highlighted.It was also verified that although we have three nearby cities with similar characteristics,it is possible to have differences of simulation results when the appropriate weather file is not used.

摘要： Understanding the folding processes of a protein into its three-dimensional native structure only with its amino-acid sequence information is a long-standing challenge in modern science. Two- hundred independent folding simulations (starting from non-native conformations) and two- hundred independent unfolding simulations (starting from the folded native structure) are performed using the united-residue force field and Metropolis Monte Carlo algorithm for betanova (three-stranded antiparallel beta-sheet protein). From these extensive computer simulations, two representative folding pathways and two representative unfolding pathways are obtained in the reaction coordinates such as the fraction of native contacts, the radius of gyration, and the root- mean-square deviation. The folding pathways and the unfolding pathways are similar each other. The largest deviation between the folding pathways and the unfolding pathways results from the root-mean-square deviation near the folded native structure. In general, unfolding computer simulations could capture the essentials of folding simulations.

摘要： The performance parameters of vapor compression refrigeration units that used the refrigerant R-404A were studied by developing a computer simulation algorithm. The various performance parameters investigated per one kilowatt of refrigeration capacity, such as the mass flow rate, the compressor power consumption, the condenser heat rejection rate, the compressor exit temperature and the coefficient of performance. Two refrigeration cycles were tested under various evaporating and condensing temperatures: the standard cycle and the ideal cycle with superheating and sub-cooling. The results of the present work reveal that the compressor power variation over the evaporating temperature range from –10°C to 15°Cat Tc = 40°C is decreased by 38.8% for standard cycle and by 43.8% for ideal cycle. The compressor power variation over the condensing temperature range from 30°C to 50°C at Te = 10°C is increased by 122% for standard cycle and by 54.5% for ideal cycle. On the other hand, the COP for the ideal cycle with 5°C superheating and sub-cooling is approximately 25% higher than that of the standard cycle at Te = 10°C and Tc = 40°C for the refrigerant R-404A.

摘要： It reviews the main methods of the study of railway capacity in the world. But in China, the defini-tion of railway capacity is different from the other countries, so the main methods of calculating railway ca-pacity are not suit to Chinese railway. We introduce the coefficient of removal analysis method to calculatethe capacity of railway with automatic block section, but its calculating result isn’t satisfying. As computertechnology improves, the auto-drawing train working diagram (TWD) has become a trend. It proposes a newapproach to calculate the railway capacity, and the calculating method is based on auto-drawing TWD andcomputer simulation. The goal of this new method is to draw the maximum number of common freight trainpaths into the original timetable where passenger train paths and important freight train paths are exist andfixed.

摘要： It reviews the main methods of the study of railway capacity in the world. But in China, the defini-tion of railway capacity is different from the other countries, so the main methods of calculating railway ca-pacity are not suit to Chinese railway. We introduce the coefficient of removal analysis method to calculatethe capacity of railway with automatic block section, but its calculating result isn’t satisfying. As computertechnology improves, the auto-drawing train working diagram (TWD) has become a trend. It proposes a newapproach to calculate the railway capacity, and the calculating method is based on auto-drawing TWD andcomputer simulation. The goal of this new method is to draw the maximum number of common freight trainpaths into the original timetable where passenger train paths and important freight train paths are exist andfixed.

摘要： It reviews the main methods of the study of railway capacity in the world. But in China, the defini-tion of railway capacity is different from the other countries, so the main methods of calculating railway ca-pacity are not suit to Chinese railway. We introduce the coefficient of removal analysis method to calculatethe capacity of railway with automatic block section, but its calculating result isn’t satisfying. As computertechnology improves, the auto-drawing train working diagram (TWD) has become a trend. It proposes a newapproach to calculate the railway capacity, and the calculating method is based on auto-drawing TWD andcomputer simulation. The goal of this new method is to draw the maximum number of common freight trainpaths into the original timetable where passenger train paths and important freight train paths are exist andfixed.

摘要： It reviews the main methods of the study of railway capacity in the world. But in China, the defini-tion of railway capacity is different from the other countries, so the main methods of calculating railway ca-pacity are not suit to Chinese railway. We introduce the coefficient of removal analysis method to calculatethe capacity of railway with automatic block section, but its calculating result isn’t satisfying. As computertechnology improves, the auto-drawing train working diagram (TWD) has become a trend. It proposes a newapproach to calculate the railway capacity, and the calculating method is based on auto-drawing TWD andcomputer simulation. The goal of this new method is to draw the maximum number of common freight trainpaths into the original timetable where passenger train paths and important freight train paths are exist andfixed.