• 제목/요약/키워드: Transport capacity

검색결과 643건 처리시간 0.023초

불응축가스 주입량에 따른 VCHP의 열제어 특성 (Analysis of Thermal Control Characteristics of VCHP by the Charging Mass of Non-Condensible Gas)

  • 서정세;박영식;정경택
    • 설비공학논문집
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    • 제17권12호
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    • pp.1139-1144
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    • 2005
  • This study has been performed to investigate the thermal performance of variable conductance heat pipe (VCHP) with meshed wick. The length of condenser portion in a VCHP is varied by the expansion of inert gas with the operation temperature, and the heat transport capacity is thus varied with the operating temperature. In this study, numerical evaluation of the VCHP is made for the thermal performance of VCHP, based on the diffusion model of inert gas. Water is used as a working fluid and nitrogen as a control inert gas in the copper tube. As a result, the thermal performance of VCHP has been compared with that of constant conductance heat pipe (CCHP) according to the variation of operation temperature. Maximum heat transport capacity of VCHP is mainly presented for operation temperature and the variation of operation temperature is also presented for heat transfer rate of VCHP.

STEAM GENERATOR TUBE INTEGRITY ANALYSIS OF A TOTAL LOSS OF ALL HEAT SINKS ACCIDENT FOR WOLSONG NPP UNIT 1

  • Lim, Heok-Soon;Song, Tae-Young;Chi, Moon-Goo;Kim, Seoung-Rae
    • Nuclear Engineering and Technology
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    • 제46권1호
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    • pp.39-46
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    • 2014
  • A total loss of all heat sinks is considered a severe accident with a low probability of occurrence. Following a total loss of all heat sinks, the degasser/condenser relief valves (DCRV) become the sole means available for the depressurization of the primary heat transport system. If a nuclear power plant has a total loss of heat sinks accident, high-temperature steam and differential pressure between the primary heat transport system (PHTS) and the steam generator (SG) secondary side can cause a SG tube creep rupture. To protect the PHTS during a total loss of all heat sinks accident, a sufficient depressurization capability of the degasser/condenser relief valve and the SG tube integrity is very important. Therefore, an accurate estimation of the discharge through these valves is necessary to assess the impact of the PHTS overprotection and the SG tube integrity of the primary circuit. This paper describes the analysis of DCRV discharge capacity and the SG tube integrity under a total loss of all heat sink using the CATHENA code. It was found that the DCRV's discharge capacity is enough to protect the overpressure in the PHTS, and the SG tube integrity is maintained in a total loss of all heat accident.

A Simulation Study of Urban Public Transport Transfer Station Based on Anylogic

  • Liu, Weiwei;Wang, Fu;Zhang, Chennan;Zhang, Jingyu;Wang, Lei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제15권4호
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    • pp.1216-1231
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    • 2021
  • With the increase in the population of our cities and the rapid increase in the number of private cars, urban traffic has become more and more congested. At this stage, urban public transportation has become one of the main ways to improve urban traffic congestion. Aiming at the problem of how to improve the basic capacity of buses in multi-line transfer stations, this paper conducts simulation research based on anylogic software. Through micro-simulation analysis of vehicles entering, stopping, and exiting the station, combined with the delay model theory, the vehicle is given Stop organization optimization and station layout improvement methods, so that vehicles can run in the station more stably, smoothly and safely. Case analysis shows that applying this method to the roadside parking problem, the main and auxiliary bus stations have a significant improvement in operating capacity compared with the conventional tandem double bus stations, and the service level of the main and auxiliary bus stations has been significantly improved.

Exploring market uncertainty in early ship design

  • Zwaginga, Jesper;Stroo, Ko;Kana, Austin
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제13권1호
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    • pp.352-366
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    • 2021
  • To decrease Europe's harmful emissions, the European Union aims to substantially increase its offshore wind energy capacity. To further develop offshore wind energy, investment in ever-larger construction vessels is necessary. However, this market is characterised by seemingly unpredictable growth of market demand, turbine capacity and distance from shore. Currently it is difficult to deal with such market uncertainty within the ship design process. This research aims to develop a method that is able to deal with market uncertainty in early ship design by increasing knowledge when design freedom is still high. The method uses uncertainty modelling prior to the requirement definition stage by performing global research into the market, and during the concept design stage by iteratively co-evolving the vessel design and business case in parallel. The method consists of three parts; simulating an expected market from data, modelling multiple vessel designs, and an uncertainty model that evaluates the performance of the vessels in the market. The case study into offshore wind foundation installation vessels showed that the method can provide valuable insight into the effect of ship parameters like main dimensions, crane size and ship speed on the performance in an uncertain market. These results were used to create a value robust design, which is capable of handling uncertainty without changes to the vessel. The developed method thus provides a way to deal with market uncertainty in the early ship design process.

Quantum modulation of the channel charge and distributed capacitance of double gated nanosize FETs

  • Gasparyan, Ferdinand V.;Aroutiounian, Vladimir M.
    • Advances in nano research
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    • 제3권1호
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    • pp.49-54
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    • 2015
  • The structure represents symmetrical metal electrode (gate 1) - front $SiO_2$ layer - n-Si nanowire FET - buried $SiO_2$ layer - metal electrode (gate 2). At the symmetrical gate voltages high conductive regions near the gate 1 - front $SiO_2$ and gate 2 - buried $SiO_2$ interfaces correspondingly, and low conductive region in the central region of the NW are formed. Possibilities of applications of nanosize FETs at the deep inversion and depletion as a distributed capacitance are demonstrated. Capacity density is an order to ${\sim}{\mu}F/cm^2$. The charge density, it distribution and capacity value in the nanowire can be controlled by a small changes in the gate voltages. at the non-symmetrical gate voltages high conductive regions will move to corresponding interfaces and low conductive region will modulate non-symmetrically. In this case source-drain current of the FET will redistributed and change current way. This gives opportunity to investigate surface and bulk transport processes in the nanosize inversion channel.

Noisy Data Aggregation with Independent Sensors: Insights and Open Problems

  • Murayama, Tatsuto;Davis, Peter
    • Journal of Multimedia Information System
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    • 제3권2호
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    • pp.21-26
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    • 2016
  • Our networked world has been growing exponentially fast. The explosion in volume of machine-to-machine (M2M) transactions threatens to exceed the transport capacity of the networks that link them. Therefore, it is quite essential to reconsider the tradeoff between using many data sets versus using good data sets. We focus on this tradeoff in the context of the quality of information aggregated from many sensors in a noisy environment. We start with a basic theoretical model considered in the famous "CEO problem'' in the field of information theory. From a point of view of large deviations, we successfully find a simple statement for the optimal strategies under the limited network capacity condition. Moreover, we propose an open problem for a sensor network scenario and report a numerical result.

아이스 슬러리의 수송 및 냉열이용에 관한 연구 (A Study on Transport and Heat Utilization of Ice Slurries)

  • 길복임;이윤표;정동주;조봉현;최은수
    • 설비공학논문집
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    • 제13권11호
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    • pp.1065-1071
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    • 2001
  • To investigate hydraulic and thermal characteristics of ice slurries in a circular tube, ice slurries were tested in a flow loop with a constant heat flux test section, for ranges of flow velocity, ice fraction and heat flux. Heat transfer coefficients and friction factors of ice slurries were calculated by measuring the outer wall temperatures of the test section and the pressure drops over the test section. Heat transfer coefficients of ice slurries were 9% higher than the heat transfer coefficients expected by Petukhov. Friction factors were about 4% lower than the friction factors expected by Petukhov. The effective thermal capacity of ice slurry with 12.8% ice fraction, was found to be about 3 times higher than the thermal capacity of water.

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공역확장을 통한 인천국제공항 수용능력 향상에 관한 고찰 (On the Design of Extending Airspace for Improving Incheon International Airport Capacity)

  • 이영종
    • 한국항행학회논문지
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    • 제19권2호
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    • pp.103-107
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    • 2015
  • 본 논문은 인천국제공항의 공역 수용 능력 향상을 시키기 위한 공역 확보 대안을 제시하고자 한다. 활주로 15/16방향 동시독립접근을 위해서는 ILS 접근절차에 대해 레이더 유도방식으로 관제업무를 제공해야 하므로, 레이더 유도가 가능한 최소 공역을 감안하여 휴전선비행금지구역(P-518) 조정을 제안하며, 동시독립접근이 가능할 경우 교통량 증가로 인한 임시 체공구역 확보를 위하여, 군 훈련공역을 단계적으로 5마일씩 총 10마일을 확보, 오산접근구역 내에 군 훈련공역 일부를 서울접근 관제소에 포함시키는 것을 제안 하고자 한다.

A Separator with Activated Carbon Powder Layer to Enhance the Performance of Lithium-Sulfur Batteries

  • Vu, Duc-Luong;Lee, Jae-Won
    • 한국분말재료학회지
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    • 제25권6호
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    • pp.466-474
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    • 2018
  • The high theoretical energy density ($2600Wh\;kg^{-1}$) of Lithium-sulfur batteries and the high theoretical capacity of elemental sulfur ($1672mAh\;g^{-1}$) attract significant research attention. However, the poor electrical conductivity of sulfur and the polysulfide shuttle effect are chronic problems resulting in low sulfur utilization and poor cycling stability. In this study, we address these problems by coating a polyethylene separator with a layer of activated carbon powder. A lithium-sulfur cell containing the activated carbon powder-coated separator exhibits an initial specific discharge capacity of $1400mAh\;g^{-1}$ at 0.1 C, and retains 63% of the initial capacity after 100 cycles at 0.2 C, whereas the equivalent cell with a bare separator exhibits a $1200mAh\;g^{-1}$ initial specific discharge capacity, and 50% capacity retention under the same conditions. The activated carbon powder-coated separator also enhances the rate capability. These results indicate that the microstructure of the activated carbon powder layer provides space for the sulfur redox reaction and facilitates fast electron transport. Concurrently, the activated carbon powder layer traps and reutilizes any polysulfides dissolved in the electrolyte. The approach presented here provides insights for overcoming the problems associated with lithium-sulfur batteries and promoting their practical use.

편성물의 섬유의 종류, 실의 굵기 및 니트타입에 따른 투습완충능력 (Effect of Fiber Content, Yarn Size and Construction of Knit Fabrics on the Buffering Capacity against Water Vapor)

  • 유화숙;허윤숙;김은애
    • 한국의류학회지
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    • 제20권1호
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    • pp.228-238
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    • 1996
  • The purpose of this study was to evaluate the effect of chacteristics of knit fabrics on the microclimate of the skin simulating system. To determine the effect of characteristics of knit fabrics, vapor state of sweat pulse was simulated in the closed system. Different contents of fibers such as cotton, wool and polyester with different yarn size and knit types were chosen for specimens. The changes of humidity and temperature of air layer in the simulated systems were measured. Buffering indices, $K_d$ and $\beta_r$, were determined by considering $\alpha_p, \DeltaP_{max}, t_{max}, and tan\beta$. Physical properties of knit fabrics such as thickness, porosity, air resistance and moisture vapor transport were measured. Results showed that vapor pressure of wool was lower than cotton or polyester This was attributed to the hydrophilicity of wool which absorbed moisture rather quickly and retained in the knit fabric. The time to decrease vapor pressure was faster for polyester than cotton or wool. As a result, $K_d$ was in the order of wool> polye, item> cotton. $\beta_r$ of wool was rower than cotton or polyester due to its lowers porosity and slower desorption rate. For the yarn size, $K_d$ was in the order of 80's> 60's> 30's; thinner and lighter yarn showed better water vapor transport property. For knit type, buffering capacity of single jersey was better than interlock knit fabric. Statistical analysis showed that the air permeability was the most influential factor far the water vapor transport properties.

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