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A comparison of optimization theories for energy conservation in heat exchanger groups

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science Bulletin 2011年第Z1期 449-454页

作者： CHEN Qun1,2,WU Jing3,WANG MoRan4,PAN Ning2 & GUO ZengYuan1 1 Key laboratory for Thermal science and Power Engineering of Ministry of Education,Department of Engineering Mechanics,Tsinghua University,Beijing 100084,China 2 Department of Biological and Agricultural Engineering,University of California,Davis CA 95616,usa 3 College of Energy and Power Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China 4 earth and environmental sciences division,los alamos national laboratory,los alamos nm 87545,usa

In general,thermal processes can be classified into two categories: heat-work conversion processes and heat transfer processes. Correspondingly,the optimization of thermal processes has to have two different criteria:the well known entropy generation minimization method and the recently proposed entransy dissipation maximization method. This study analyzes the thermal issues in a heat exchanger group,and optimizes the unit arrangements under different constraints based on a suitable optimization crite-rion. The result indicates that the principle of minimum entropy generation rate is valid for optimizing heat exchangers in a ther-modynamic cycle with given boundary temperatures. In contrast,the entransy dissipation maximization is more suitable in heat exchanger optimizations involving only heat transfer processes. Furthermore,the entropy generation rate induced by dumping used streams into ambient surroundings has to be taken into account,except for that originating from the hot and cold-ends of heat exchangers,when using the entropy generation minimization to optimize heat exchangers undergoing a thermodynamic cycle.

关键词： heat exchangers optimization criterion entransy dissipation maximization entropy generation minimization

Photosynthetically active radiation retrieval based on HJ-1A/B satellite data

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science China earth sciences 2010年第S1期53卷 81-91页

作者： LI Li1,XIN XiaoZhou1,sU GaoLi1,2 & LIU QinHuo1 1 state Key laboratory of Remote sensing science,Institute of Remote sensing Applications,Chinese Academy of sciences,Beijing 100101,China 2 Zhejiang Climate Center,Hangzhou 310017,China 1. state Key laboratory of Remote sensing science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China2. Zhejiang Climate Center Hangzhou 310017 China

Photosynthetically active radiation(PAR) is essential for plant photosynthesis and carbon cycle,and is also important for meteorological and environmental *** advance China's disaster and environmental monitoring capabilities,the HJ-1A/B satellites have been placed in earth *** of their environmental monitoring objectives is the study of *** simulated direct solar,scattered and environment radiation between 400 and 700 nm under different atmospheric parameters(solar zenith angle,atmospheric water vapor,atmospheric ozone,aerosol optical thickness,surface elevation and surface albedo),and then established a look-up table between these input parameters and *** on the look-up table,we used HJ-1A/B aerosol and surface albedo outputs to derive the corresponding *** of inversed instantaneous and observed PAR values using HJ-1 Heihe experimental data had a root mean square error of 25.2 W m-2,with a relative error of 5.9%.The root mean square error for accumulated daily PAR and observed values was 0.49 MJ m-2,with a relative error of 3.5%.Our approach improved significantly the computational efficiency,compared with using directly radiation transfer *** also studied the sensitivity of various input parameters to photosynthetically active radiation,and found that solar zenith angle and atmospheric aerosols were sensitive PAR *** albedo had some effect on PAR,but water vapor and ozone had minimal impact on PAR.

关键词： Photosynthetically active radiation 6s HJ-1A/B satellites

Magnetic characterization of noninteracting,randomly oriented,nanometer-scale ferrimagnetic particles

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Magnetic characterization of noninteracting,randomly oriente...

Photoluminescence,thermally stimulated luminescence and dosimetry properties of dysprosium doped strontium phosphate phosphors

中国科学院地质与地球物理研究所第十届(2010年度)学术年会

作者： Changqian Cao,Lanxiang Tian,Qingsong Liu,Weifeng Liu,Guanjun Chen, and Yongxin Pan 1 Paleomagnetism and Geochronology laboratory,Key laboratory of the earth’s Deep Interior,Institute of Geology and Geophysics,Chinese Academy of sciences,Beijing,China. 2 Also at France-China Bio-Mineralization and Nano-structures laboratory,Institute of Geology and Geophysics,Chinese Academy of sciences,Beijing,China. 3 Also at Graduate University of Chinese Academy of sciences,Beijing, China. 4 state Key laboratory of Microbial Technology,school of Life sciences,shandong University,Jinan,China.

[1]studying the magnetic properties of ultrafine nanometer-scale femmagnetic particles (<10 nm)is vital to our understanding of superparamagnetism and its applications to environmental magnetism,biogeomagnetism,iron b...

[1]studying the magnetic properties of ultrafine nanometer-scale femmagnetic particles (nm)is vital to our understanding of superparamagnetism and its applications to environmental magnetism,biogeomagnetism,iron biomineralization,and biomedical ***,magnetic properties of the ultrafine nanometer-sized femmagnetic grains are very poorly constrained because of ambiguities caused by particle magnetostatic interactions and unknown size *** resolve these problems,we synthesized magnetoferritins using the recombinant human H chain ferritin(HFn). These femmagnetic HFn were further purified through size exclusion chromatography to obtain monodispersed ferrimagnetic *** electron microscopy revealed that the purified ferrimagnetic HFn are monodispersed and each consists of an iron oxide core(magnetite or maghemite)with an average core diameter of 3.9±1.1 nm imbedded in an intact protein *** R value of the Wohlfarth-Cisowski test measured at 5 K is 0.5,indicating no magnetostatic *** saturation isothermal remanent magnetization acquired at 5 K decreased rapidly with increasing temperature with a median unblocking temperature of 8.2 *** preexponential frequency factor f determined by AC susceptibility is(9.2±7.9)×*** extrapolated M/M and B/B at 0 K are 0.5 and 1.12,respectively,suggesting that the ferrimagnetic HFn cores are dominated by uniaxial *** calculated effective magnetic anisotropy energy constant K=1.2×10 J/m,which is larger than previously reported values for bulk magnetite and/or maghemite or magnetoferritin and is attributed to the effect of surface *** data provide useful insights into superparamagnetism as well as biomineralization of ultrafine ferrimagnetic particles.

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Photoluminescence,thermally stimulated luminescence and dosi...

Facile one-pot sonochemical synthesis of hydrophilic ultrasmall LaF3:Ce,Tb nanoparticles with green luminescence

第七届全国稀土发光材料学术研讨会

作者： Li Juan~(1,2,9) Zhou Huijun~1 Zhang Liwei~1 Zhang Chunxiang~3 Tang Qiang~3 Hao Jingquan~2 Zhang Yanli~4,su Qiang~(2,5) Wang shubin~2 (1 Chemistry and Biology College of Beihua University,Jilin,132013,P.R.China) (2 Key Laboratoiy of Rare earth Chemistry and Physics,Changchun Institute of Applied Chemistry, Chinese Academy of science,Changchun,130022,P.R.China) (3 Department of Physics,sun Yat-sen University,Guangzhou,510275,P.R.China) (4 Ionizing Radiation division,national Institute of Metrology,Beijing,130000,P.R.China) (5 state Key Laboratoiy of Optoelectivnic Materials and Technology,school of Chemistry and Chemical Engineering,sun Yat-sen University,Guangzhou,510275,P.R.China)

Thermally stimulated luminescence(TsL) is widely employed for radiation dosimetry and geological *** stimulated luminescence(TsL) dosimetry has been developed to the stage that it represents a key technique in absorbed dose *** in radiation dosimetry by the TsL technique has resulted in numerous efforts seeking production of new,high-performance TsL materials due to their potential applications in clinical,personal and environmental monitoring for both ionizing and non-ionizing radiation. Polycrystalline powder samples of dysprosium doped sr(PO4):Dy phosphors were prepared by solid state reaction in air at high temperature and characterized by x-ray powder diffraction in this work. The excitation spectrum for Dy in the sample sr(PO):Dy by monitoring the emission at 577nm exhibited H→D(294nm),H→P(326nm),H→P(350nm),H→P(367nm), H→M(389nm)andH→G(432nm)forbidden f-f transitions of Dy *** emission broad band at about 423nm,475nm,577nm,665nm and 750nm attributed to the host emission and F→H,F→H,F→HandF→Hf-f transitions of Dy ions by excited with wavelength 350nm were observed. The diffuse reflectance spectra of sr(PO):Dy after and before 60Co gamma-ray irradiation and the subtracting spectrum were studied in 200000nm wavelength *** absorption bands were observed in the subtracting spectrum,the first one at about 260nm,and the later two bands at about 403 and 632 nm. The TsL emission spectrum of sr(PO):Dy by 60Co gamma-rays irradiation at 293k showed that the characteristic emission bands at about 450nm,480nm,575 nm,665nm,750nm attributed to the host emission and F→H,F→H,F→Hand F→Hf-f transitions of Dy ions, agreeing basically with the photoluminescence(PL),*** of emission spectrum of PL and TsL originate from the same luminescent centers of Dy *** emission from Dy or Dy ions was observed in the measurement waveiength *** relative TsL intensity was plotted as a function of 60Co gamma-rays irradiation dose for the s

关键词： Thermally stimulated luminescence Dosimetry strontium phosphate

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Progress in Natural science:Materials International 2012年第5期22卷 488-492页

作者： Lisha Zhang a,Wei Li b,Xianghua Hu b,Yanlin Peng b,Junqing Hu b,Xingyu Kuang b,Linlin song b,Zhigang Chen b a state Key laboratory for Modification of Chemical Fibers and Polymer Materials,College of environmental science and Engineering,Donghua University,shanghai 201620,China b College of Materials science and Engineering,Donghua University,shanghai 201620,China [a] state Key laboratory for Modification of Chemical Fibers and Polymer Materials College of Environmental Science and Engineering Donghua University Shanghai 201620 China [b] College of Materials science and Engineering Donghua University Shanghai 201620 China

Rare earth nanoparticles(RENPs) have great superiority as luminescent materials for broad applications,and a prerequisite for most of their application is to obtain hydrophilic RENPs with efficient luminescence and small diameter(nm).To address this problem,we report a facile one-pot sonochemical route with tetraethylene glycol as the solvent and tetrafluoroborate-based ionic liquid as the fluorine source for the synthesis of LaF3:Ce,Tb as the model of ***3:Ce,Tb nanoparticles with the diameter of about 6 nm were prepared in a very short ultrasound time(10min).Fourier transform infrared spectrum reveals the presence of tetraethylene glycol ligands on their surface,which confers high solubility of LaF3:Ce,Tb nanoparticles in *** 254 nm UV excitation,the aqueous dispersion of LaF3:Ce,Tb nanoparticles exhibits strong green emission with luminescent quantum yield of 50%.This work probably contributes to not only the fundamental research of shape-controlled LaF3:Ce,Tb nanoparticles but also new methods of producing other RENPs for broad applications.

关键词： sonochemical synthesis LaF3:Ce,Tb Nanoparticles Luminescence

Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance

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science China earth sciences 2006年第4期49卷 431-442页

作者： ZHANG Yunlin1, 2, QIN Boqiang1, HU Weiping1, WANG sumin1, CHEN Yuwei1 & CHEN Weimin1 1. Nanjing Institute of Geography & Limnology, Chinese Academy of sciences, Nanjing 210008, China 2. Graduate school of the Chinese Academy of sciences, Beijing 100039, China 1. Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China 2. Graduate school of the Chinese Academy of sciences Beijing 100039 China

By using the data of underwater irradiance measured in the different lakeregions of Lake Taihu during 1998—2004 and total suspended solids (Tss), wind speeds of the total13 stations in typical lake regions during 1993—2003, this paper analyzes the factors ofinfluencing on PAR (pho-tosynthetically available radiation) attenuation, euphotic depth, andpresents the temporal and spatial variations of euphotic depth of typical lake regions in LakeTaihu, and the spectral distributions of euphotic depth at station 2. The results show that theconcentration of Tss is the most important factor impacting PAR attenuation, followed by chlorophylla; chromophoric dissolved organic matter (CDOM) has little impact on the PAR euphotic depth. During1993—2003, the mean yearly PAR euphotic depths of the typical lake regions ranged from 1.04 to1.95 m with a mean value of 1.35±0.23 m. The PAR euphotic depth fell into 3 spatial zone types:Type Ⅰ, the lowest, including the lake center and the inflows of rivers; Type Ⅱ, intermediate,including Meiliang Bay, Wulihu Lake and Gonghu Bay; Type Ⅲ, the greatest, including the East LakeTaihu; corresponding mean depths were approximately 1.1, 1.4, 2.0 m, respectively. The seasonalvariations of euphotic depths were not quite the same in different lake regions. In the lake center,the mean values of PAR euphotic depth in summer and autumn were significantly greater than those inwinter and spring; in the Meiliang Bay, winter means were significantly greater than in the otherthree seasons; in the East Lake Taihu, winter means were significantly less than in the other threeseasons. However, no distinct seasonal change was recorded in the Wulihu Lake, Gonghu Bay and theinflows of rivers. The spectral distributions of euphotic depth present a minimal value at the bluelight wave band of 400 nm, and a peak at the green light wave band of around 580 nm. In 1998 and1999, based on the seasonal many-day continuous measurements, the PAR euphotic depths at station 2w

关键词： lake taihu euphotic depth diffuse attenuation coefficient total suspendedsolid ecological

Combustion synthesis of Ce^(3+), Eu^(3+) and Dy^(3+) activated NaCaPO_4 phosphors

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Journal of Rare earths 2011年第6期29卷 527-535页

作者： K N shinde s J Dhoble Animesh Kumar Department of Physics RTM Nagpur University national environmental Engineering Research Institute

The preparation of NaCaPO4 doped with rare earth （RE） ions Ce3＋, Eu3＋ and Dy3＋ by combustion method was described. Under UV excitation （251 nm） of NaCaPO4：Ce3＋ showsd emission （367 nm） in UV range. When NaCaPO4：Dy3＋ phosphor was excited at 349 nm, the emission spectrum showed intense bands at 482 nm （blue） and 576 nm （yellow）. In Eu activated NaCaPO4 phosphor, the emission spectrum showed a dominant peak at 594 nm （orange） while others were at 614 and 621 nm （red） when excited at 393 nm. The prepared phosphor was characterized by X-ray diffraction （XRD）, scanning electron microscope （sEM） and photoluminescence （PL） measurement. Thus, the photoluminescence behavior of NaCaPO4：Ce3＋ was strongly suggested for scintillator. Likewise, Eu3＋ and Dy3＋ activated NaCaPO4 phosphors were recommended for near-UV white light-emitting diodes （LEDs）.

关键词： combustion synthesis photoluminescence phosphor scintillator solid state lighting rare earths

LED Determination Methods of sulfur Dioxide Concentration in Air

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LED Determination Methods of Sulfur Dioxide Concentration in...

Unsupervised phase mapping of X-ray diffraction data by nonnegative matrix factorization integrated with custom clustering

2011 IEEE International Conference on Waste Recycling,Ecology and Environment(ICWREE 2011)

作者： Chunmei LIU1* Zhang ZHANG2 Wen CAO1 Lei XU1 1 school of Information Engineering southwest University of science &Technology Mianyang 621010 China 2 College of Physics and Electronic Information China West Normal University Nanchong 637002 China

sulfur dioxide （sO2） gas is one of the major pollution in the atmosphere whose content is an important air quality indicator assessed by environmental monitor stations. In this paper, an ultraviolet LED is applied as light source whose centre wavelength is 300nm. Having got through the sample cell, the light is divided into the reference light and sample light with different sO2 concentration by the spectroscope. The light intensity modulation factor can be calculated by measuring the difference of spectral intensity of the two lights, thus the sO2 gas concentration is rated. The concentration calibration curve with very high linearity can be obtained by means of measuring several groups of sO2 with different concentration. This study shows that the measurement method can be applied in the measurement of sO2 concentration with low cost, anti- interference and high sensitivity.

关键词： ultraviolet LED sO2 light intensity modulation index

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npj Computational Materials 2018年第1期4卷 295-304页

作者： Valentin stanev Velimir V.Vesselinov A.Gilad Kusne Graham Antoszewski Ichiro Takeuchi Boian s.Alexandrov Department of Materials science and Engineering University of MarylandCollege ParkMD 20742USA Center for Nanophysics and Advanced Materials University of MarylandCollege ParkMD 20742USA Joint Quantum Institute University of MarylandCollege ParkMD 20742USA los alamos national laboratory Earth Science DivisionLos AlamosNM 87545USA national Institute of standards and Technology GaithersburgMD 20899USA Department of Mathematics University of MarylandCollege ParkMD 20742USA los alamos national laboratory Theoretical DivisionLos AlamosNM 87545USA

Analyzing large X-ray diffraction(XRD)datasets is a key step in high-throughput mapping of the compositional phase diagrams of combinatorial materials *** and automating this task can help accelerate the process of discovery of materials with novel and desirable ***,we report a new method for pattern analysis and phase extraction of XRD *** method expands the Nonnegative Matrix Factorization method,which has been used previously to analyze such datasets,by combining it with custom clustering and cross-correlation *** new method is capable of robust determination of the number of basis patterns present in the data which,in turn,enables straightforward identification of any possible peak-shifted ***-shifting arises due to continuous change in the lattice constants as a function of composition and is ubiquitous in XRD datasets from composition spread *** identification of the peak-shifted patterns allows proper quantification and classification of the basis XRD patterns,which is necessary in order to decipher the contribution of each unique single-phase structure to the multi-phase *** process can be utilized to determine accurately the compositional phase diagram of a system under *** presented method is applied to one synthetic and one experimental dataset and demonstrates robust accuracy and identification abilities.

关键词： properties. phase nonnegative