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An Experimental Study of Condensation Heat Transfer in Sub-Millimeter Rectangular Tubes

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Journal of Thermal Science 2004年第4期13卷 350-357页

作者： Jeong Seob shin Moo Hwan KIM Department of Mechanical Engineering POSTECH Pohang KoreaDepartment of Mechanical Engineering POSTECH Pohang Korea

The characteristics of local heat transfer and pressure drops were experimentally investigated using condensing R134a two-phase flow, in single rectangular tubes, with hydraulic diameter of 0.494, 0.658, and 0.972 mm. New experimental techniques were used to measure the in-tube condensation heat transfer coefficient especially for the low heat and mass flows. Tests were performed for a mass flux of 100, 200, 400, and 600 kg/m2s, a heat flux of 5 to 20 kW/m2, and a saturation temperature of 40℃. In this study, effect of heat flux, mass flux, vapor qualities, and hydraulic diameter on flow condensation were investigated and the experimental local condensation heat transfer coefficients and frictional pressure drop are shown. The experimental data of condensation Nusselt number are compared with previous correlations, most of which are proposed for the condensation of pure refrigerant in a relatively large inner diameter round tubes.

关键词： condensation hydraulic diameter rectangular in-tube multiphase flow.

Difficulties, strategies, and recent research and development of layered sodium transition metal oxide cathode materials for high-energy sodium-ion batteries

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Journal of Energy Chemistry 2024年第3期90卷 40-57,I0003页

作者： Kouthaman Mathiyalagan Dongwoo shin Young-Chul Lee Department of Nano Science and Technology Convergence Gachon University1342 Seongnam-DaeroSujeong-GuGyeonggi-DoSeongnam-Si 13120Republic of Korea Department of Bio Nano Technology Gachon University1342 Seongnam-DaeroSujeong-GuGyeonggi-DoSeongnam-Si 13120Republic of Korea

Energy-storage systems and their production have attracted significant interest for practical *** are the foundation of sustainable energy sources for electric vehicles(EVs),portable electronic devices(PEDs),*** recent decades,Lithium-ion batteries(LIBs) have been extensively utilized in largescale energy storage devices owing to their long cycle life and high energy ***,the high cost and limited availability of Li are the two main obstacles for *** this regard,sodium-ion batteries(SIBs) are attractive alternatives to LIBs for large-scale energy storage systems because of the abundance and low cost of sodium *** is one of the most important components in the battery,which limits cost and performance of a *** the classified cathode structures,layered structure materials have attracted attention because of their high ionic conductivity,fast diffusion rate,and high specific ***,we present a comprehensive review of the classification of layered structures and the preparation of layered ***,the review article discusses extensively about the issues of the layered materials,namely(1) electrochemical degradation,(2) irreversible structural changes,and(3) structural instability,and also it provides strategies to overcome the issues such as elemental phase composition,a small amount of elemental doping,structural design,and surface alteration for emerging *** addition,the article discusses about the recent research development on layered unary,binary,ternary,quaternary,quinary,and senary-based O3-and P2-type cathode materials for high-energy *** review article provides useful information for the development of high-energy layered sodium transition metal oxide P2 and O3-cathode materials for practical SIBs.

关键词： O3-type P2-type Cathode materials Sodium-ion batteries Layered structure

Miniature planar telescopes for efficient,wide-angle,high-precision beam steering

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Light(Science & Applications) 2021年第8期10卷 1445-1454页

作者： Ziqian He Kun Yin shin-Tson Wu College of Optics and Photonics University of Central FloridaOrlandoFL 32816USA

Non-mechanical beam steerers with lightweight,compact,high-efficiency,high-precision,and/or large-angle are pivotal for light detection and ranging(LiDAR)of autonomous vehicles,eye-tracking for near-eye displays,microscopy,optical tweezers,and high-precision three-dimensional(3D)***,even the most matured optical phased array can only provide quasi-continuous,efficient beam steering within a small angle range.A telescope module with an angle magnification function can be coupled to enlarge the steering range or *** obtaining a compact,low-cost,lightweight,high-quality telescope module with conventional optics remains *** liquid crystal-based planar optical elements offer great design freedom for manipulating the phase profile of light in 2D *** to the advantages of high efficiency,thinness,low cost,easy processing,flexibility,and response to environmental stimuli,a plethora of high-quality optical devices have been ***,a miniature planar telescope mediated by liquid crystal polymers is proposed to offer angle magnification independent of incident spatial *** consists of two cascaded liquid crystal planar optical elements,each performing a predefined mathematical *** this concept,planar optical elements are fabricated using a new exposure method and assembled into planar telescopes with different magnification *** the incident field range,over 84.6%optical efficiency is achieved with small wavefront *** a miniature planar telescope shows the potential of cascaded liquid crystal planar optical elements for realizing functionalities that cannot be fulfilled by single optical elements,and enables lightweight,low loss,passive optical transmitters for widespread applications.

关键词： angle beam telescope

The Minimal Free Resolution of a Fat Star-Configuration in Pn

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Algebra Colloquium 2014年第1期21卷 157-166页

作者： Jeaman Ahn Yong Su shin Department of Mathematics Education Kongju National University 182 Shinkwan-dong Kongju Chungnam 314-701 Korea Department of Mathematics Sungshin Women's University Seoul 136-742 Korea

Abstract. We find the minimal free resolution of a fat star-configuration X in Pn of type （r, s,t） defined by general forms of degrees d1,...,dr, and show that a fat linear star- configuration X in P2 never has generic Hilbert function if （s,t） ≠ （1, 1） or （2, 2）. These two results generalize the interesting results of [2].

关键词： Hilbert functions minimal free resolutions weak Lefschetz property fat star-configurations

ROBUST DESIGN MODELS FOR CUSTOMER-SPECIFIED BOUNDS ON PROCESS PARAMETERS

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Journal of Systems Science and Systems Engineering 2006年第1期15卷 2-18页

作者： Sangmun shin Byung Rae CHO Department of Systems Management&Engineering Inje University GimhaeKyung Nam 621-749South Korea Department of Industrial Engineering Clemson University ClemsonSouth Carolina 29634USA

Robust design (RD) has received much attention from researchers and practitioners for years, and a number of methodologies have been studied in the research community. The majority of existing RD models focus on the minimum variability with a zero bias. However, it is often the case that the customer may specify upper bounds on one of the two process parameters (i.e., the process mean and variance). In this situation, the existing RD models may not work efficiently in incorporating the customer’s needs. To this end, we propose two simple RD models using the ε?constraint feasible region method - one with an upper bound of process bias specified and the other with an upper bound on process variability specified. We then conduct a case study to analyze the effects of upper bounds on each of the process parameters in terms of optimal operating conditions and mean squared error.

关键词： Robust design Process bias process variability response surface methodology ε?constraint method optimization

Climatic Classification over Asia during the Middle Holocene Climatic Optimum Based on PMIP Models

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Journal of Earth Science 2016年第1期27卷 123-129页

作者： Hyuntaik Oh Ho-Jeong shin Center for Marine Environmental Impact Assessment National Fisheries Research and Development Institute Ocean Circulation and Climate Research Division Korea Institute of Ocean Science and Technology

When considering potential global warming projections, it is useful to understand the impact of each climate condition at 6 kyr before present. Asian paleoclimate was simulated by performing an integration of the multi-model ensemble with the paleoclimate modeling intercomparison project（PMIP） models. The reconstructed winter（summer） surface air temperature at 6 kyr before present was 0.85 oC（0.21 oC） lower（higher） than the present day over Asia, 60oE-150oE, 10oN-60oN. The seasonal variation and heating differences of land and ocean in summer at 6 kyr before present might be much larger than present day. The winter and summer precipitation of 6 kyr before present were 0.067 and 0.017 mm·day-1larger than present day, respectively. The Group B climate, which means the dry climates based on K？ppen climate classification, at 6 kyr before present decreased 17% compared to present day, but the Group D which means the continental and microthermal climates at 6 kyr before present increased over 7%. Comparison between the results from the model simulation and published paleo-proxy record agrees within the limited sparse paleo-proxy record data.

关键词： paleoclimate modeling intercomparison project (PMIP) paleoclimate global warming,Asian continent.

Integration of climate change considerations into environmental impact assessment- implementation, problems and recommendations for China

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Frontiers of Environmental Science & Engineering 2013年第4期7卷 598-607页

作者： I-shin CHANG Jing WU College of Environment and Resources Inner Mongolia University Huhhot 010021 China College of Environmental Science and Engineering Nankai University Tianjin 300071 China

Climate change plays an important role in affecting and altering the course of human development. So far, there have been no effective and efficient techniques to directly quantify the influences of climate change on human development, but there have been rough estimation and qualitative description of the effects. Since the 1990s, climate change considerations have been required to be included in environmental impact assess- ment, which is a flexible institutional framework of environmental risk evaluation and management. However, there have been no concrete achievements demonstrated. The purpose of this study was first to summarise the practical experience and to disclose the existing problems during the implementation of the process of integrating climate change considerations into environmental impact assessment in China through a case study. Currently in China, the practice of integrating climate change con- siderations into environmental impact assessment is mainly concentrated on the strategic environmental assessment level. The influences of climate change were identified as energy consumption, greenhouse gases emission, and the restraint of development under abnormal or extreme weather or climate conditions. Because of a lack of related technical guidelines and practical experi- ence, the climate change considerations that have been selected and the evaluation methods that have been applied are quite different. Recommendations on policies, laws, and institutional regulations institution are proposed to better utilise environmental impact assessment to integrate climate change considerations into economic, social, and environmental decisions and actions.

关键词： climate change considerations environmental

Initialization for NMF-Based Audio Source Separation Using Priors on Encoding Vectors

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China Communications 2019年第9期16卷 177-186页

作者： Jaeuk Byun Jong Won shin Electrical Engineering and Computer Science Gwangju Institute of Science and Technology (GIST)

Nonnegative matrix factorization(NMF)has shown good performances on blind audio source separation(BASS).While the NMF analysis is a non-convex optimization problem when both the basis and encoding matrices need to be estimated simultaneously,the source separation step of the NMF-based BASS with a fixed basis matrix has been considered ***,because the basis matrix for the BASS is typically constructed by concatenating the basis matrices trained with individual source signals,the subspace spanned by the basis vectors for one source may overlap with that for other *** this paper,we have shown that the resulting encoding vector is not unique when the subspaces spanned by basis vectors for the sources overlap,which implies that the initialization of the encoding vector in the source separation stage is not ***,we propose a novel method to initialize the encoding vector for the separation step based on the prior model of the encoding *** results showed that the proposed method outperformed the uniform random initialization by 1.09 and 2.21dB in the source-to-distortion ratio,and 0.20 and 0.23 in PESQ scores for supervised and semi-supervised cases,respectively.

关键词： blind audio source separation nonnegative matrix factorization speech enhancement

Advancing from scalar to vectorial liquid crystal holography:a paradigm shift

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Light(Science & Applications) 2024年第9期13卷 1696-1697页

作者： Yan Li shin-Tson Wu Department of Electronic Engineering Shanghai Jiao Tong UniversityShanghai 200240China College of Optics and Photonics University of Central FloridaOrlandoFL 32816USA

A versatile and tunable vectorial holography is demonstrated based on single-layer single-material liquid crystal *** novel approach advances the process from scalar to vectorial holography,opening new opportunities f... 详细信息

关键词： liquid crystal versatile