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Study of the circulation theory of the cooling system in vertical evaporative cooling generator

工程和商业管理国际学术会议

作者： Zhang Li-ning1 2 zhang Qi1 Lin Da-chao2 An-jing2 (1.beijing institute of technology achademy of mechanical-electrical engineering beijing China 100081 2.North China institute of science and technology civil engineering department beijing Yanjiao China 101601)

The pre-warning of enterprise financial crisis is a hot studying spot in current theory field, and also becomes a considering focus in reality field. This paper firstly overviews the present research conditions of enterprise financial crisis pre-warning, sets up the pre-warning index system. Then makes reduction on the index system and finds the core unascertained factors which influence enterprise financial safety by using the Rough Sets（RS）. On this basis, accomplishes the financial risk pre-warning based on the great nonlinear function approaching capability of artificial nerve network（ANN）. Against for the shortage of ANN, this paper introduces the Particle Swarm Optimization（PSO）, sets up a crisis forecast system to the enterprise financial crisis based on RS and ANN with PSO. Thus making the index system reduction, the dynamic study and induction of ANN, the Particle Swarm Optimization, the forecast and evaluation of enterprise financial crisis organically combined. At last, gives an actual example to justify the validity and efficiency of this model. This study supplies a new method for the dynamic pre-warning of enterprise financial crisis.

关键词： Rough sets Particle swarm optimization Artificial nerve network Enterprise financial crisis pre-warning

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Science China(Technological Sciences) 2006年第3期49卷 358-364页

作者： YU Shunzhou1, CAI jing2, GUO Chaohong1 & GU Guobiao1 1. institute of Electrical Engineering, Chinese Academy of Sciences, beijing 100080, China 2. beijing Changcheng institute of Metrology and Measurement, beijing 100095, China institute of Electrical Engineering Chinese Academy of Sciences Beijing China beijing Changcheng institute of Metrology and Measurement Beijing China

The article briefly states the current development of evaporative cooling generator; its advantages comparing with generators of traditional cooling. Vertical evaporative cooling generator, which adopts Close-Loop-Self-Cycle with no-pump; free convection boil in the hollow stator bar, is one of the great developments in generator design. This article emphasizes the importance of cooling system in generator; expatiates the circulation theory in two aspects, energy; flow;; analyzes the essential reason, motivity; stability of Close-Loop-Self-Cycle. The article points out that the motivity of the circulation is the heat absorbed by coolant. After absorbing heat the coolant will have the ability of doing work because of the phase change. In another words, it is the buoyancy causing by density difference leads to the Close-Loop-Self-Cycle. This conclusion is validated by experimental data.

关键词： vertical evaporative cooling generator, cooling system, circulation theory.

Density functional theory study of the reaction paths of reactions of CH3C（O）O2 radicals with HO2 in the gas phase

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Progress in Natural Science:Materials International 2006年第12期16卷 1269-1274页

作者： ZHOU Yuzhi~ 1,2 , ZHANG Shaowen~1 and LI Qianshu~1**(1. State Key Laboratory of Explosion Science and technology, beijing institute of technology, beijing 100081, China 2. beijing institute of Education, beijing 100044, China) State Key Laboratory of Explosion Science and technology Beijing Institute of Technology Beijing 100081 China beijing institute of Education Beijing 100044 China

A DFT study on the reactions between CH_3C（O）O_2and HO_2radicals has been carried out. It is suggested that both the triplet and singlet potential surfaces involve a complex mechanism with the formation of loosely bound intermediate complexes of reactants and products. The reaction prefers to occur on the triplet surface to produce peracetic acid (CH_3C（O）O_2H) and triplet O_2molecule. The CH_3C（O）O_2H can further convert into CH_3C（O）O and HO radicals.

关键词： acetyl peroxy radicals HO2 radicals reaction mechanism DFT.

An analysis of seismic attenuation in random porous media

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Science China(Physics,Mechanics & Astronomy) 2010年第4期53卷 628-637页

作者： LIU Jiong1, BA jing2, MA JianWei1 & YANG HuiZhu1 1 institute of Seismic Exploration, School of Aerospace, Tsinghua University, beijing 100084, China 2 Research institute of Petroleum Exploration & Development, PetroChina, beijing 100083, China institute of Seismic Exploration School of Aerospace Tsinghua University Beijing China Research institute of Petroleum Exploration & Development PetroChina Beijing China

The attenuation of seismic wave in rocks has been one of the interesting research topics, but till now no poroelasticity models can thoroughly explain the strong attenuation of wave in rocks. In this paper, a random porous medium model is designed to study the law of wave propagation in complex rocks based on the theory of Biot poroelasticity and the general theory of stochastic process. This model sets the density of grain, porosity, permeability and modulus of frame as random parameters in space, and only one fluid infiltrates in rocks for the sake of better simulation effect in line with real rocks in earth strata. Numerical simulations are implemented. Two different inverse quality factors of fast P-wave are obtained by different methods to assess attenuation through records of virtual detectors in wave field (One is amplitude decay method in time domain and the other is spectral ratio method in frequency domain). Comparing the attenuation results of random porous medium with those of homogeneous porous medium, we conclude that the attenuation of seismic wave of homogeneous porous medium is far weaker than that of random porous medium. In random porous media, the higher heterogeneous level is, the stronger the attenuation becomes, and when heterogeneity σ = 0.15 in simulation, the attenuation result is consistent with that by actual observation. Since the central frequency (50 Hz) of source in numerical simulation is in earthquake band, the numerical results prove that heterogeneous porous structure is one of the important factors causing strong attenuation in real stratum at intermediate and low frequency.

关键词： the theory of stochastic process the theory of Biot poroelasticity the attenuation of seismic wave inverse quality factor

Microstructure and Frictional Behavior of Fe-based Amorphous Metallic Coatings Prepared by Atmospheric Plasma Spraying

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稀有金属材料与工程 2011年第S3期40卷 160-165页

作者： Zhou Zheng1,2, Wang Lu2, He Dingyong1, Liu Yanbo2, Zhang Guanzhen1 1.beijing University of technology, beijing 100124, China 2 beijing institute of technology, beijing 100081, China beijing Univ Technol Beijing 100124 Peoples R China beijing Inst Technol Beijing 100081 Peoples R China

Amorphous metallic coatings with a composition of Fe48Cr15Mo14C15B6Y2 were prepared by means of atmospheric plasma spraying (APS) process under different conditions. The microstructure and frictional behavior were characterized simultaneously in this article. The results show that the as-deposited coatings consist of amorphous matrix and some precipitated nanocrystals, while the amorphous fraction and particle deformation as well as crystallization mechanism are significantly sensitive to the spraying parameters. The amorphous coatings express high microhardness and excellent wear resistance under dry frictional wear condition, which attributes to the inherent characteristic of amorphous phase and the dispersion strengthening of precipitated nanocrystals. The dominant wear mechanism of the amorphous coatings is fatigue wear accompanying with oxidative wear. In addition, the microhardness and wear resistance of the amorphous coatings were improved by optimizing spraying parameters, owing to the effect of both structural character and proper proportional of amorphous and nanocrystals fraction.

关键词： Fe-based amorphous coating APS microstructure friction

Augmented reality registration algorithm based on nature feature recognition

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Science China(Information Sciences) 2010年第8期53卷 1555-1565页

作者： CHEN jing 1 , WANG YongTian 1,2 , GUO JunWei 1 , LIU Wei 1 , LIN jingDun 1 , XUE Kang 1 , LIU Yue 1 & DING GangYi 31 School of Optoelectronics, beijing institute of technology, beijing 100081, China 2 School of Computer Science and technology, beijing institute of technology, beijing 100081, China 3 School of Software, beijing institute of technology, beijing 100081, China School of Optoelectronics Beijing Institute of Technology Beijing China School of Computer Science and technology Beijing Institute of Technology Beijing China School of Software Beijing Institute of Technology Beijing China

This paper presents an improved key frame based augmented reality registration algorithm for real-time motion tracking in outdoor environment. In such applications, wide-baseline feature matching is a critical problem. In this paper, we apply randomized tree method to match key points extracted from the input image to those key frames as a classification problem. Extended Kalman filter is also utilized for jitter correction. A video see-through mobile augmented reality system is built for the on-site digital reconstruction of Yuanmingyuan Garden. Experimental results demonstrate that this algorithm is real-time, robust and effective for outdoor tracking.

关键词： outdoor augmented reality camera tracking randomized tree

Ni-Cu bimetallic alloy anchored on nitrogen-doped carbon nanotubes for CO_(2)-to-CH_(4) electrochemical conversion

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Nano Research 2024年第8期17卷 6922-6930页

作者： jing Li Chuanyong jing Jin Wang School of Environment Beijing Key Laboratory of Aqueous Typical Pollutants Control and Water Quality SafeguardBeijing Jiaotong UniversityBeijing 100044China State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Tangshan Research institute Beijing Jiaotong UniversityTangshan 063000China

Electrocatalytic CO_(2) reduction to CH_(4) remains challenging due to multi-electron transfer and intermediates ***,we synthesized electrocatalysts by growing Ni-Cu alloy structure on nitrogen-doped carbon nanotubes(NixCuy-NCNT)for electrocatalytic CO_(2) reduction reaction(CO_(2)RR)via hydrothermal method followed by *** optimized Ni_(1)Cu_(1)-NCNT demonstrated a superior CO_(2)RR performance,achieving 99.7%FECH_(4)(FE=Faradaic efficiency)and 11.54 mA·cm^(−2) current density at−1.2 V *** hydrogen electrode(RHE),which outperformed single metal *** outstanding performance was due to the electrons transferred from Cu to Ni and Ni-Cu alloy shifted the d-band center toward the Fermi level,which was more conducive to the intermediate *** situ electrochemical attenuated total reflection(EC-ATR)and density functional theory(DFT)calculations revealed the appearance of *CHO intermediate and the pathway during the CO_(2)RR *** design of the bimetallic electrocatalyst in this study provides a new perspective for the highly selective reduction of CO_(2).

关键词： electrocatalytic CO_(2) reduction Ni-Cu alloy nitrogen-doped carbon nanotube(NCNT) electrochemical attenuated total reflection(EC-ATR) density functional theory(DFT)calculations

Measurement Methodology for Monitoring Fouling Resistance in Condenser of Chiller

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湖南大学学报（自然科学版） 2009年第S1期36卷 119-122页

作者： YU Dan1,3,GAN Li-si1,CAO Yong2(1.beijing University of technology,beijing 100022,China 2.Build Environment and Energy Efficiency,China Academy of Building Research,beijing 100013,China 3.beijing institute of Civil Engineering and Architecture,beijing 100044,China) beijing University of technology Beijing 100022 China beijing institute of Civil Engineering and Architecture Beijing 100044 China Build Environment and Energy Efficiency China Academy of Building Research Beijing 100013 China

This paper established an on-line monitoring model for fouling resistance of cooling water based on heat transfer theory,which was mainly applied to the fouling resistance test for condenser of chiller in operation,and the test requirements were *** proves that the load ratio of chiller has big influence on the test result,and the best load ratio for test is the range of 80%～100%.A case has been executed to validate the model's feasibility.

关键词： fouling resistance monitoring condenser cooling water

Fractional Fourier domain equalization for single carrier broadband wireless systems

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Science China(Information Sciences) 2012年第10期55卷 2257-2268页

作者： HUANG KeWu 1,2,TAO Ran 1 & WANG Yue 1 1 Department of Electronic Engineering,beijing institute of technology,beijing 100081,China 2 institute of Manned Space System Engineering,China Academy of Space technology,beijing 100094,China Department of Electronic Engineering Beijing Institute of Technology Beijing China institute of Manned Space System Engineering China Academy of Space Technology Beijing China

In this paper,a novel single carrier equalization approach in the fractional Fourier domain(FRFD) is *** can remove all the inter-symbol interference(ISI) and avoid the considerable noise enhancement of the frequency domain-zero forcing(FD-ZF) *** the fractional Fourier transform makes a chirp spread,the impulse response of the deep fading channel may be flattened in some orders of the FRFD while it would be greatly attenuated in the *** searching for an optimal order under certain criterion,we take advantages of the ZF algorithm to mitigate the effects of the ISI *** approach can overcome the contradiction between the ISI mitigation and the noise enhancement of the FD-ZF *** analysis and simulation results show that the proposed FRFD-ZF equalizer can achieve a significant performance and have the same computation cost O(N log N) as the conventional FD linear equalizer,especially in the frequencyselective deep-fading channels.

关键词： fractional Fourier transform single carrier systems zero-forcing equalizer frequency domain linear equalizer

An uncertainty investigation for liner impedance eduction methods

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Chinese Journal of Aeronautics 2024年第3期37卷 49-59页

作者： Weihao SHI Xiaodong jing School of Energy and Power Engineering Beihang UniversityBeijing 100191China

Impedance eduction methods have been developed for decades to meet the increasing need for high-quality impedance data in the design and optimization of acoustic *** this end,it is important to fully investigate the uncertainty problem,to which only limited attention has been devoted so *** paper considers the possibility of acoustically-induced structural vibration as a nonnegligible uncertainty or error source in impedance eduction *** the frequency moves away from the resonant frequency,with the increase in the value of cavity reactance,the acoustic particle velocity inside liner orifices possibly decreases to the extent comparable to the vibration velocity of liner facing ***,the acoustically-induced vibration,although generally being weak except at the inherent structural frequencies,may considerably affect the impedance eduction results near the anti-resonant frequency where the liner has poor *** demonstrate the effect of structural vibration,the vibration velocity of liner facing sheet is estimated from the experimentally educed admittance of the liner samples whose orifices are sealed with ***,a three-dimensional numerical model is set up,in which normal particle velocity is introduced over the solid portion of liner facing sheet to imitate structural vibration,rather than directly solving the acoustic-structural coupling *** shown by the results,the vibration of liner facing sheet,whose velocity is as small as estimated by the experiment,can result in anomalous deviation of the educed impedance from the impedance model near the anti-resonant *** trend that the anomalous deviation varies with frequency is numerically captured.

关键词： Impedance eduction Uncertainty analysis Acoustically-induced structural vibration Anti-resonant frequency Perforated liner