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Direct numerical simulation of turbulent boundary layer over an anisotropic compliant wall

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Acta Mechanica Sinica 2019年第2期35卷 384-400页

作者： Qian-Jin Xia Wei-Xi Huang chun-xiao xu AML Department of Engineering MechanicsTsinghua University Beijing 100084 China

Direct numerical simulation of a spatially developing turbulent boundary layer over a compliant wall with anisotropic wall material properties is performed. The Reynolds number varies from 300 to approximately 860 along the streamwise direction, based on the external flow velocity and the momentum thickness. Eight typical cases are selected for numerical investigation under the guidance of the monoharmonic analysis. The instantaneous flow fields exhibit the traveling wavy motion of the compliant wall, and the frequency-wavenumber power spectrum of wall pressure fluctuation is computed to quantify the mutual influence of the wall compliance and the turbulent flow at different wave numbers. It is shown that the Reynolds shear stress and the pressure fluctuation are generally enhanced by the wall compliance with the parameters considered in the present study. A dynamical decomposition of the skin-friction coefficient is derived, and a new term (CW) appears due to the wall-induced Reynolds shear stress. The influence of the anisotropic compliant wall motion on the turbulent boundary layer through the wall-induced negative Reynolds shear stress is discussed. To elucidate the underlying mechanism, the budget analysis of the Reynolds stresses transportation is further carried out. The impact of the wall compliance on the turbulent flow is disclosed by examining the variations of the diffusion and velocity-pressure correlation terms. It is shown that increase of the Reynolds stresses inside the flow domain is caused by enhancement of the velocity-pressure correlation term, possibly through the long-range influence of the wall compliance on the pressure field, rather than diffusion of the wall-induced Reynolds shear stress into the fluid flow.

关键词： Turbulent boundary layer Anisotropic compliant wall Direct numerical simulation Skin-friction coefficient Reynolds shear stress

Thermal stability of nanocrystalline layer prepared by surface mechanical attrition in 0Cr18Ni9Ti stainless steel

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中国有色金属学会会刊：英文版 2004年第z1期14卷 210-214页

作者： WANG Hong-bin WU xiao-chun xu Ling-yun School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Materials Science and Engineering Shanghai University Shanghai 200072 China

By means of surface mechanical attrition (SMA), a nanostructured surface layer was formed on a 0Cr18Ni9Ti austenite stainless steel plate. A strain-induced martensite transformation was observed during SMA treatment, and a single magnetic martensite phase layer with thickness of about 30 μm was gotten. The grain growth and phase transformations in the nanocrystalline layer are investigated during heating. The grain growth exponent for nanocrystalline polycrystalline steel is estimated. The kinetics mechanism governing the grain growth in the nanocrystalline layer is discussed. The martensite in the surface layer is quite stable and the temperature at which the reverse transformation of martensite to austenite starts during heating is about 500 ℃.

关键词： grain growth phase transformation surface mechanical attrition surface nanocrystalline layer

Lost expression of thyroid hormone receptor-β1 mRNA in esophageal cancer

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Frontiers in Biology 2012年第4期7卷 368-373页

作者： Hao LI xiao-chun xu Department of Clinical Cancer Prevention UTM. D. Anderson Cancer Center Houston TX 77030 USA Department of Pathology Anhui Medical University Hefei 230032 China

Thyroid hormone receptors （TR）, ligand-mediated transcription factors, regulate cell growth, differentiation, and apoptosis. In humans, two different genes encode TR-α and TR-β and they are often co-expressed in various tissues at different levels. To explore the role of TR in esophageal cancer, we analyzed expression of TR-β1 mRNA （most abundantly expressed in the majority of normal cells） in normal and malignant esophageal tissue specimens using in situ hybridization. The TR-β1 mRNA was detected in 92.3% （96 of 104） of normal esophageal mucosa, whereas TR-β1 mRNA was only detected in 55.8% （58 of 104 cases） of esophageal squamous cell carcinoma specimens （P〈 0.00001）. Expression of TR-β1 mRNA was associated with well-differentiated cancers （P〈 0.001）. Furthermore, we determined whether the loss of heterozygosity （LOH） in TR-β1 gene locus would be responsible for the lost TR-β1 expression. Analysis of 73 esophageal tissue specimens generated 39 informative cases, 17 of which showed LOH （43.6%） but only 9 of these 17 cases were correlated with lost TR-β1 expression. This study demonstrated that expression of TR-β1 mRNA was lost in esophageal cancer tissues, which may be due to multiple mechanisms.

关键词： esophageal cancer thyroid hormone receptor in situ hybridization LOH

Characteristic pattern of human prostatic growth with age

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Asian Journal of Andrology 2002年第4期4卷 269-271页

作者： Shu-Jie XIA xiao-Xin xu Jian-Bao TENG chun-xiao xu xiao-Da TANG Department of Urology Shanghai 1st People's HospitalShanghai 200080China Department of Urology Linqu People's HospitalLinquShandong 262600China Department of Urology Shandong Provincial HospitalJinan 250021China

Aim: To study the characteristic pattern of the age-related growth of the human prostate gland. Methods: The volume (weight) of the prostate in 1,601 males, aged from newborn to 92 years, was determined by Bultrasonography. Results: Prostatic volume determination by B-ultrasonography in 1601 males (1301 normal subjects and 300 BPH patients) pointed out that the age-stratified growth of human prostate could be categorized into 4 life stages: (1) the first slow growing phase (from newborn to 9 years): the prostate grows slowly at a rate of 0.14g per year; (2) the first rapid growing phase (from 10 to 30 years): the prostate grows at a rate of 0.84 g per year; (3) the second slow growing phase (from 30 to 50 years), the prostate grows at a rate of 0.21 g per year; (4) the second rapid growing phase (from 50 to 90 years): the prostate grows at one of the following rates: in one group the growth rate is of 0.50 g per year and in the other 1.20 g per year, leading to benign prostatic hyperplasia (BPH). Conclusion: The volumes of the prostate are different in different age groups and it grows with age at different rates in four life phases. The prostate growth in phases can be expressed by the following equation: Y=19.36+1.36X'-0.58X'2+0.33X'3, where Y=prostate volume, X=age (up to 70 years), X'=(X-35.5)/10. (Asian JAndrol 2002 Dec; 4: 269-271)

关键词： prostatic hypertrophy age factor B-ultrasonography androgen

New Individual Identification Method of Radiation Source Signal Based on Entropy Feature and SVM

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Journal of Harbin Institute of Technology(New Series) 2014年第1期21卷 98-101页

作者： Yun Lin xiao-chun xu Zi-Cheng Wang College of Information and Communication Engineering Harbin Engineering University

In this paper,according to the defect of methods which have low identification rate in low SNR,a new individual identification method of radiation source based on information entropy feature and SVM is presented. Firstly,based on the theory of multi-resolution wavelet analysis,the wavelet power spectrum of noncooperative signal can be gotten. Secondly,according to the information entropy theory,the wavelet power spectrum entropy is defined in this paper. Therefore,the database of signal's wavelet power spectrum entropy can be built in different SNR and signal parameters. Finally,the sorting and identification model based on SVM is built for the individual identification of radiation source signal. The simulation result indicates that this method has a high individual's identification rate in low SNR,when the SNR is greater than 4 dB,the identification rate can reach 100%. Under unstable SNR conditions,when the range of SNR is between 0 dB and 24 dB,the average identification rate is more than 92. 67%. Therefore,this method has a great application value in the complex electromagnetic environment.

关键词： radiation source individual identification wavelet power spectrum information entropy support vector machine

Research of Hybrid Modulation Radar Signal

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Journal of Harbin Institute of Technology(New Series) 2013年第3期20卷 35-39页

作者： Kai-Feng Guo Yun Lin Meng Wang xiao-chun xu Unit 91635 of the Chinese People Liberation Army

Based on the advantage of phase coded signal and stepped frequency signal,a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulation between the pulses, which is named as phase-coded stepped-frequency ( PCSF ) signal. By analyzing its waveform and ambiguity function,the comparison between Stepped-Frequency ( SF) signal and PCSF signal is given,which shows that the PCSF signal is better than SF signal. Finally,the signal processing method with two stage compressed processing is presented. The simulation results show that this new hybrid modulation radar signal can get a higher stepped frequency than ordinary SF signal,realize the same equivalent bandwidth with less pulse number,and solve the conflict among the stepped frequency,the number of pulse, and transmit average power. Under the premises of a certain range resolution,this new hybrid modulation radar signal not only raises the data rate of radar system,but also reduces Doppler sensitivity with a good prospect, and the effect of one-dimensional range profile is much better than that of traditional SF signal. Therefore,this new hybrid modulation radar signal can be widely used in application.

关键词： phase coded stepped frequency hybrid modulation signal ambiguity function signal processing

Research of Velocity Compensation Method Based on Range Profile Feature

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Journal of Harbin Institute of Technology(New Series) 2013年第2期20卷 81-85页

作者： Kai-Feng Guo Yun Lin Meng Wang xiao-chun xu College of Information and Communication Engineering Harbin Engineering University

In this paper,based on the feature of high resolution one-dimensional range profile,two effective motion compensation methods are presented. Firstly,the processing method of stepped-frequency and the response of target moving to range profile are analyzed. Secondly,the function of range profile entropy and range profile contrast are presented for velocity compensation,and then the theory analysis,math model,and solution method are analyzed in detail. Finally,several simulation experiments are designed to prove the accuracy and effectiveness of these two methods. From the final theory analysis and simulation experiments,the conclusion can be drawn that these two methods are effective,which can get much higher velocity estimation accuracy,well real-time and easy to be used in project application. After motion compens-ation,the high resolution one-dimensional range profile will be much better than that used to be,and is used for the detection, recognition and ranging of moving targets.

关键词： stepped frequency velocity compensation range profile range profile entropy range profile contrast

An Introduction to Convex Optimization Theory in Communication Signals Recognition

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Journal of Harbin Institute of Technology(New Series) 2013年第5期20卷 14-19页

作者： Jin-Feng Pang Yun Lin xiao-chun xu Zheng Dou Zi-Cheng Wang College of Information and Communication Engineering Harbin Engineering University

In this paper,convex optimization theory is introduced into the recognition of communication signals. The detailed content contains three parts. The first part gives a survey of basic concepts,main technology and recognition model of convex optimization theory. Special emphasis is placed on how to set up the new recognition model of communication signals with multisensor reports. The second part gives the solution method of the recognition model,which is called Logarithmic Penalty Barrier Function. The last part gives several numeric simulations,in contrast to D-S evidence inference method,this new method can also generate reasonable recognition results. Moreover,this new method can deal with the form of sensor reports which is more general than that allowed by the D-S evidence inference method,and it has much lower computation complexity than that of D-S evidence inference method. In addition,this new method has better recognition result,stronger anti-interference and robustness. Therefore,the convex optimization methods can be widely used in the recognition of communication signals.

关键词： convex optimization theory signal recognition D-S evidence theory logarithmic penalty barrier function

Suppression of esophageal cancer cell growth using curcumin,(-)-epigallocatechin-3-gallate and lovastatin

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World Journal of Gastroenterology 2012年第2期18卷 126-135页

作者： Fei Ye Gui-Hong Zhang Bao-Xiang Guan xiao-chun xu Department of Clinical Cancer Prevention The Universityof Texas MD Anderson Cancer Center Houston TX 77030United States Department of Pathology Anhui Medical University Hefei 230032 Anhui ProvinceChina

AIM:To determine the effects of curcumin,(-)-epigallocatechin-3-gallate (EGCG),lovastatin,and their combinations on inhibition of esophageal ***:Esophageal cancer TE-8 and SKGT-4 cell lines were subjected to cell viability methyl thiazolyl tetrazolium and tumor cell invasion assays in vitro and tumor formation and growth in nude mouse xenografts with or without curcumin,EGCG and lovastatin *** expression was detected using immunohistochemistry and Western blotting in tumor cell lines,tumor xenografts and human esophageal cancer tissues,***:These drugs individually or in combinations significantly reduced the viability and invasion capacity of esophageal cancer cells in ***,these three agents reduced the expression of phosphorylated extracellular-signal-regulated kinases (Erk1/2),c-Jun and cyclooxygenase-2 (COX-2),but activated caspase 3 in esophageal cancer *** nude mouse xenograft assay showed that EGCG and the combinations of curcumin,EGCG and lovastatin suppressed esophageal cancer cell growth and reduced the expression of Ki67,phosphorylated Erk1/2 and *** expression of phosphorylated Erk1/2 and COX-2 in esophageal cancer tissue specimens was also analyzed using *** data demonstrated that 77 of 156 (49.4%) tumors expressed phosphorylated Erk1/2 and that 121 of 156 (77.6%) esophageal cancers expressed COX-2 *** particular,phosphorylated Erk1/2 was expressed in 23 of 50 (46%) cases of esophageal squamous cell carcinoma (SCC) and in 54 of 106 (50.9%) cases of adenocarcinoma,while COX-2 was expressed in 39 of 50 (78%) esophageal SCC and in 82 of 106 (77.4%) esophageal ***:The combinations of curcumin,EGCG and lovastatin were able to suppress esophageal cancer cell growth in vitro and in nude mouse xenografts,these drugs also inhibited phosphorylated Erk1/2,c-Jun and COX-2 expression.

关键词： Chemoprevention Curcumin Cyclooxygen-ase-2 (-)-epigallocatechin-3-gallate Esophageal can-cer Statin