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Numerical Study on Breaking Criteria for Solitary Waves

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China Ocean Engineering 2003年第4期18卷 589-604页

作者： Chung-ren CHOU Ruey-syan SHIH John z. YIM Department of Harbor and River Engineering Taiwan Ocean University Keelung ChinaDepartment of Civil Engineering Tung Nan Institute of Technology Taipei ChinaDepartment of Harbor and River Engineering Taiwan Ocean University Keelung China

Studies of the breaking criteria for solitary waves on a slope are presented in this paper. The boundary element method is used to model the processes of shoaling and breaking of solitary waves on various slopes. Empirical formulae that can be used to characteriz. the breaking of solitary waves are presented. These include the breaking index, the wave height, the water depth, and the maximum particle velocity at the point of breaking. Comparisons with the results of other researches are given.

关键词： boundary element breaking indices empirical formula solitary wave

On a general theory for compressing process and aeroacoustics:linear analysis

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Acta Mechanica Sinica 2010年第3期26卷 355-364页

作者： E .Mao Y. P. Shi J. z. Wu State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University 100871 Beijing China University of Tennessee Space Institute Tullahoma TN 37388 USA

Of the three mutually coupled fundamental processes （shearing, compressing, and thermal） in a general fluid motion, only the general formulation for the compress- ing process and a subprocess of it, the subject of aeroacous- tics, as well as their physical coupling with shearing and thermal processes, have so far not reached a consensus. This situation has caused difficulties for various in-depth complex multiprocess flow diagnosis, optimal configuration design, and flow/noise control. As the first step toward the desired formulation in fully nonlinear regime, this paper employs the operator factoriz.tion method to revisit the analytic linear theories of the fundamental processes and their decomposi- tion, especially the further splitting of compressing process into acoustic and entropy modes, developed in 1940s-1980s. The flow treated here is small disturbances of a compressible, viscous, and heat-conducting polytropic gas in an unbounded domain with arbitrary source of mass, external body force, and heat addition. Previous results are thereby revised and extended to a complete and unified theory. The theory pro- vides a necessary basis and valuable guidance for developing corresponding nonlinear theory by clarifying certain basic issues, such as the proper choice of characteristic variables of compressing process and the feature of their governing equations.

关键词： Longitudinal (compressing) processTransversal (shearing) process Acoustic mode Entropy mode Aeroacoustics

Inactivation, reactivation and regrowth of indigenous bacteria in reclaimed water after chlorine disinfection of a municipal wastewater treatment plant

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Journal of Environmental Sciences 2013年第7期25卷 1319-1325页

作者： Dan Li Siyu z.ng April z. Gu Miao He Hanchang Shi Environmental Simulation and Pollution Control State Key Joint Laboratory School of Environment Tsinghua University Department of Civil and Environmental Engineering Northeastern University

Disinfection of reclaimed water prior to reuse is important to prevent the transmission of pathogens. Chlorine is a widely utiliz.d disinfectant and as such is a leading contender for disinfection of reclaimed water. To understand the risks of chlorination resulting from the potential selection of pathogenic bacteria, the inactivation, reactivation and regrowth rates of indigenous bacteria were investigated in reclaimed water after chlorine disinfection. Inactivation of total coliforms, Enterococcus and Salmonella showed linear correlations, with constants of 0.1384, 0.1624 and 0.057 L/（mg·min） and R 2 of 0.7617, 0.8316 and 0.845, respectively. However, inactivation of total viable cells by measurement of metabolic activity typically showed a linear correlation at lower chlorine dose （0-22 （mg·min）/L）, and a trailing region with chlorine dose increasing from 22 to 69 （mg·min）/L. Reactivation and regrowth of bacteria were most likely to occur after exposure to lower chlorine doses, and extents of reactivation decreased gradually with increasing chlorine dose. In contrast to total coliforms and Enterococcus, Salmonella had a high level of regrowth and reactivation, and still had 2% regrowth even after chlorination of 69 （mg·min）/L and 24 hr storage. The bacterial compositions were also significantly altered by chlorination and storage of reclaimed water, and the ratio of Salmonella was significantly increased from 0.001% to 0.045% after chlorination of 69 （mg·min）/L and 24 hr storage. These trends indicated that chlorination contributes to the selection of chlorine-resistant pathogenic bacteria, and regrowth of pathogenic bacteria after chlorination in reclaimed water with a long retention time could threaten public health security during wastewater reuse.

关键词： inactivation regrowth reactivation indigenous bacteria reclaimed water

LOW CYCLE FATIGUE BEHAVIOR OF Az.1HP ALLOY IN AS HIGHP RESSURE DIE CASTING

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Acta Metallurgica Sinica(English Letters) 2000年第4期13卷 961-966页

作者： Liu, z. Xu, Y.Y. Wang, z.G. Wang, Y. Liu, z.Y. Inst of Metal Research Chinese Acad of Sciences Shenyang China

Fully reversed total strain-controlled low-cycle fatigue tests were conducted at room temperature in air to study the fatigue behavior of Az.1HP magnesium alloy in as high pressure die casting and subsequently heat treatment. All the specimens in different heat histories exhibit cyclic strain hardening in different degrees. It is difficult to distinguish the fatigue behavior of the die casting specimens from that of the solution aging specimens. The solution treated specimens show longer fatigue life at high strain amplitude and shorter fatigue life at low strain amplitude than the die casting and solution aging specimens though they have the lowest yield strength with higher strain hardening. Fatigue fracture surfaces for strain amplitude larger than 0.005 show very similar to those found by monotonic tensile tests. The SEM examination reveals that the regions of fatigue crack growth and final fracture can be characteriz.d by quasi-cleavage mechanisms, but some shallow dimples, slip bands and secondary cracks are found on the fracture surface in the fracture crack growth areas.

关键词： Cracks Die casting Fatigue of materials Heat treatment

Mesoporous Carbon-Tin Nanocomposites as Anode Materials for Li-ion Battery

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Journal of Materials Science & Technology 2008年第4期24卷 657-660页

作者： z. W.z.ao z.P.Guo P. Yao H.K.Liu Institute for Superconducting and Electronic Materials University of Wollongong NSW 2522 Australia ARC Centre of Excellence for Electromaterials Science University of Wollongong NSW 2522 Australia Centre for Analysis and Measurement Tianjin University Tianjin 300072 China

A new mesoporous carbon-tin （MC-Sn） nanocomposite has been successfully prepared via a two-step method. From the transmission electron microscopy （TEM） observations, the tin nanoparticles were decorated on the as-prepared mesoporous carbons. The mesoprous structure of the carbon can effectively buffer the volume changes during the Li-Sn alloying and de-alloying cycles. The as-prepared MC/Sn nanocomposite electrodes exhibited extremely good cycling stability, with the specific capacity of Sn in the composite electrode calculated to be 959.7 mAh-g-1, which amounts to an impressive 90.9% of the theoretical value （990 mAh-g-1）. The reversible capacity after 200 cycles is 96.1% of the first cycle reversible capacity, i.e., the capacity fade rate is only 0.0195% per cycle, which is even better than that of commercial graphite-based anodes.

关键词： Mesoporous Carbon Tin Nanocomposites Lithium ion battery

A Modified Entropy Generation Number for Heat Exchangers

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Journal of Thermal Science 1996年第4期5卷 257-263页

作者： z. M. Xu S. R. Yang z. Q. Chen Department of Power Engineering Northeast China Institute of Electric Power Engineering Jilin City China Energy and Power Machinery Engineering Institute Xi’an Jiaotong University Xi’an China

This paper demonstrates the difference between the entropy generation number method proposed by Bejan and the method of entropy generation per unit amount of heat transferred in analyz.ng the thermodynamic performance of heat exchangers, points out the reason for leading to the above difference.A modified entropy generation number for evaluating the irreversibility of heat exchangers is proposed which is in consistent with the entropy generation per unit amount of heat transferred in entropy generation analysis. The entropy generated by friction is also investigated. Results show that when the entropy generated by friction in heat exchangers is taken into account, there is a minimum total entropy generation number while the NTU and the ratio of heat capacity rates vary. The existence of this minimum is the prerequisite of heat exchanger optindz.tion.

关键词： entropy generation heat exchanger.

Measurement, modelling, and closed-loop control of crystal shape distribution： Literature review and future perspectives

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Particuology 2016年第3期14卷 1-18页

作者： Cai Y. Ma Jing J. Liu Xue z. Wang Institute of Particle Science and Engineering School of Chemical and Process Engineering University of Leeds Leeds 1.52 9JT United Kingdom School of Chemistry and Chemical Engineering South China University of Technology Guangzhou 510640 China

Crystal morphology is known to be of great importance to the end-use properties of crystal products, and to affect down-stream processing such as filtration and drying. However, it has been previously regarded as too challenging to achieve automatic closed-loop control. Previous work has focused on controlling the crystal siz. distribution, where the siz. of a crystal is often defined as the diameter of a sphere that has the same volume as the crystal. This paper reviews the new advances in morphological population balance models for modelling and simulating the crystal shape distribution （CShD）, measuring and estimating crystal facet growth kinetics, and two- and three-dimensional imaging for on-line characterisation of the crystal morphology and CShD. A framework is presented that integrates the various components to achieve the ultimate objective of model-based closed-loop control of the CShD. The knowledge gaps and challenges that require further research are also identified.

关键词： Crystal morphology Crystal shape distribution Morphological population balance mode3D process imaging Closed-loop control of crystal shapeCrystal facet growth kinetics

Speech Separation Methodology for Hearing Aid

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Computer Systems Science & Engineering 2023年第2期44卷 1659-1678页

作者： Joseph Sathiadhas esra Y.Sukhi Meenakshi Sundararajan Engineering College ChennaiTamil naduIndia R.M.K.Engineering College KavaraipettaiTamil naduIndia

In the design of hearing aids(HA),the real-time speech-enhancement is *** digital hearing aids should provide high signal-to-noise ratio,gain improvement and should eliminate *** generic hearing aids the perfor-mance towards different frequencies varies and non *** noise can-cellation and speech separation methods drops the voice magnitude under the noise *** performance of the HA for frequency response is non *** noise suppression methods reduce the required signal strength ***,the performance of uniform sub band analysis is poor when hearing aid is *** this paper,a speech separation method using Non-negative Matrix Fac-toriz.tion(NMF)algorithm is proposed for wavelet *** Proposed non-uniformﬁlter-bank was validated by parameters like band power,Signal-to-noise ratio(SNR),Mean Square Error(MSE),Signal to Noise and Dis-tortion Ratio(SINAD),Spurious-free dynamic range(SFDR),error and *** speech recordings before and after separation was evaluated for quality using objective speech quality measures International Telecommunication Union-Telecommunication standard ITU-T P.862.

关键词： Speech separation waveletﬁlter independent component analysis(ICA) non-negative matrix factoriz.tion(NMF) fejer-korovkin(FK) signal-to-noise ratio(SNR)

Structural and Optical Properties of Nanocrystal In203 Films by Thermal Oxidation of In2S3 Films

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Chinese Physics Letters 2006年第6期23卷 1610-1612页

作者： M. OEz.as M. Bedir z. OEz.ürk D. Korkmaz.S. Sur Department of Engineering Physics University of Gaziantep 27310 Gaziantep Turkey

In2S3 nanocrystalline films are prepared on glass substrates by the spray pyrolysis technique using indium chloride and thiourea as precursors. The deposition is carried out at 350℃ on glass substrates. The films are then annealed for two hour at 200, 400, 600, and 800℃ in O2 flow. This process allows the transformation of nanocrystal In203 films from In2S3 films and the reaction completes at 600℃. These results indicate that the In2O3 film prepared by this simple thermal oxidation method is a promising candidate for electro-optical and photovoltaic devices.

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