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The Superiorities of Bayes Linear Unbiased Estimator in Multivariate Linear Models

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Acta Mathematicae Applicatae Sinica 2012年第2期28卷 383-394页

作者： wei-ping ZHANG Lai-sheng wei Yu chen Department of Statistics and Finance University of Science and Technology of China Hefei 230026 China

In this article, the Bayes linear unbiased estimator （BALUE） of parameters is derived for the multivariate linear models. The superiorities of the BALUE over the least square estimator （LSE） is studied in terms of... 详细信息

关键词： multivariate linear models Bayes linear unbiased estimator least square estimator mean squareerror matrix criterion Bayesian Pitman closeness criterion

Precipitate Behavior in Fe–20Cr–30Ni–2Nb Austenitic Heat-Resistant Steel

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Acta Metallurgica Sinica(English Letters) 2015年第4期28卷 424-429页

作者： Hiroki Ishikawa Chi Zhang sheng-wei chen Zhi-Gang Yang School of Materials Science and Engineering Tsinghua University Department of Chemistry and Materials Science Tokyo Institute of Technology

In this study, the precipitation behavior of a new austenitic heat-resistant steel （Fe-20Cr-30Ni-2Nb, in at%） was investigated. The effects of alloying addition of boron （B） and lanthanum （La） on the microstructure of the austenitic steel were scrutinized using SEM, EPMA, TEM, and XRD. The results showed that the addition of B enhanced the precipitation of bar-type Laves phase. A small precipitate with high La concentration was observed at the grain boundary in the alloy without aging; similar precipitates without La also presented in region adjacent to the La single phase. This result indicates that La can exist independently and does not contribute to the formation of new compounds. However, in both B- and La-modified alloy, B appeared in the precipitate free zone. In the alloy containing both B and La, only Fe2Nb Laves- phase precipitates, as indicated by the XRD result.

关键词： Precipitation free zone Grain boundary Phase transformation Microstructure Fe-20Cr-30Ni-2Nb austenitic heat-resistant steel

Observer-based Adaptive Iterative Learning Control for Nonlinear Systems with Time-varying Delays

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International Journal of Automation and computing 2010年第4期7卷 438-446页

作者： wei-sheng chen Rui-Hong Li Jing Li Department of Applied Mathematics Xidian University X{an 710071 PRC

An observer-based adaptive iterative learning control （AILC） scheme is developed for a class of nonlinear systems with unknown time-varying parameters and unknown time-varying delays. The linear matrix inequality （LMI） method is employed to design the nonlinear observer. The designed controller contains a proportional-integral-derivative （PID） feedback term in time domain. The learning law of unknown constant parameter is differential-difference-type, and the learning law of unknown time-varying parameter is difference-type. It is assumed that the unknown delay-dependent uncertainty is nonlinearly parameterized. By constructing a Lyapunov-Krasovskii-like composite energy function （CEF）, we prove the boundedness of all closed-loop signals and the convergence of tracking error. A simulation example is provided to illustrate the effectiveness of the control algorithm proposed in this paper.

关键词： Adaptive iterative learning control (AILC) nonlinearly parameterized systems time-varying delays Lyapunov- Krasovskii-like composite energy function.

UNSTEADY FLOW ANALYSIS AND EXPERIMENTAL INVESTIGATION OF AXIAL-FLOW PUMP

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Journal of Hydrodynamics 2010年第1期22卷 35-43页

作者： ZHANG De-sheng SHI wei-dong chen Bin GUAN Xing-fan Technical and Research Center of Fluid Machinery Engineering Jiangsu University Zhenjiang 212013 China

The three-dimensional unsteady turbulent flow in axial-flow pumps was simulated based on Navier-Stoke solver embedded with k - ε RNG turbulence model and SIMPLEC algorithm. Numerical results show that the unsteady prediction results are more accurate than the steady results, and the maximal error of unsteady prediction is only 4.54%. The time-domain spectrums show that the static pressure fluctuation curves at the inlet and outlet of the rotor and the outlet of the stator are periodic, and all have four peaks and four valleys. The pressure fluctuation amplitude increases from the hub to the tip at the inlet and outlet of the rotor, but decreases at the outlet of the stator. The pressure fluctuation amplitude is the greatest at the inlet of the rotor, and the average amplitude decreases sharply from the inlet to the outlet. The frequency spectrums obtained by Fast Fourier Transform （FFT） show that the dominant frequency is approximately equal to the blade passing frequency. The static pressure on the pressure side of hydrofoil on different stream surfaces remains almost consistent, and increases gradually from the blade inlet to the exit on the suction side at different time steps. The axial velocity distribution is periodic and is affected by the stator blade number at the rotor exit. The experimental results show that the flow is almost axial and the pre-rotation is very small at the rotor inlet under the conditions of 0.8 QN -1.2 QN Due to the clearance leakage, the pressure, circulation and meridional velocity at the rotor outlet all decrease near the hub leakage and tip clearance regions.

关键词： axial-flow pump unsteady flow pressure fluctuation high efficiency flow field measurement

Antibacterial properties and corrosion resistance of AISI 420 stainless steels implanted by silver and copper ions

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International Journal of Minerals,Metallurgy and Materials 2012年第4期19卷 322-327页

作者： Hong-wei Ni Han-shuang Zhang Rong-sheng chen wei-ting Zhan Kai-fu Huo Zhen-yu Zuo Key Laboratory for Ferrous Metallurgy and Resources Utilization of the Ministry of Education School of Materials and Metallurgy Wuhan University of Science andTechnology Wuhan 430081 China

Silver or copper ions are often chosen as antibacterial agents. But a few reports are concerned with these two antibacterial agents for preparation of antibacterial stainless steel （SS）. The antibacterial properties and corrosion resistance of AISI 420 stainless steel implanted by silver and copper ions were investigated. Due to the cooperative antibacterial effect of silver and copper ions, the Ag/Cu implanted SS showed excellent antibacterial activities against both Gram-negative Escherichia coli （E. coli） and Gram-positive Staphylococcus aureus （S. aureus） at a total implantation dose of 2~ 1017 ions/cm2. Electrochemical polarization curves revealed that the corrosion resistance of Ag/Cu implanted SS was slightly enhanced as compared with that of un-implanted SS, The implanted layer was characterized by X-ray photoelec- tron spectroscopy （XPS）. Core level XPS spectra indicate that the implanted silver and copper ions exist in metallic state in the implanted layer.

关键词： ion implantation antibacterial properties stainless steel Escherichia coli Staphylococcus aureus corrosion resistance

The first experience of multi-gripper robot assisted percutaneous coronary intervention in complex coronary lesions

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Journal of Geriatric Cardiology 2023年第8期20卷 608-611页

作者： Pan LI Liang ZHANG Bo LI wei-Po chen wei-sheng chen Zhi-Fu GUO Bi-Li ZHANG Department of Cardiology Changhai HospitalNaval Medical UniversityShanghaiChina Department of Cardiology Shanghai 411 HospitalChina RongTong Medical Healthcare Group Co.Ltd.ShanghaiChina

With advances in the field of interventional cardiology,percutaneous coronary intervention(PCI)has become one of the main treatment methods for patients with coronary artery disease in clinical practice.^([1])Routine interventional therapy is performed under fluoroscopic guidance,and interventional cardiologists are therefore often exposed to *** a result,the risks of cancer,cataract,hair loss and loss of skin pigmentation will be significantly incre-ased after long-term radiation exposure.

关键词： coronary percutaneous lesions

Arg-gly-asp-mannose-6-phosphate inhibits activation and proliferation of hepatic stellate cells in vitro

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World Journal of Gastroenterology 2006年第8期12卷 1303-1307页

作者： Lian-sheng Wang Ying-wei chen Ding-Guo Li Han-Ming Lu Digestive Disease Laboratory Xinhua Hospital Shanghai Second Medical University Shanghai 200092 China

AIM： To investigate the effect of arg-gly-asp-mannose-6 phosphate （RGD-M6P） on the activation and proliferation of primary hepatic stellate cells in vitro. METHODS： Hepatic steUate cells （HSCs） were isolated from rats by in situ collagenase perfusion of liver and 18% Nycodenz gradient centrifugation and cultured on uncoated plastic plates for 24 h with DMEM containing 10% fetal bovine serum （FBS/DMEM） before the culture medium was substituted with 2% FBS/DMEM for another 24 h. Then, HSCs were cultured in 2% FBS/DMEM with transforming growth factor 131, M6P, RGD, or RGD- M6P, respectively. Cell morphology was observed under inverted microscope, smooth muscle α-actin （α-SMA） was detected by immunocytochemistry, type Ⅲ procollagen （PCⅢ） in supernatant was determined by radioimmunoassay, and the proliferation rate of HSCs was assessed by flow cytometry. RESULTS： RGD-M6P significantly inhibited the morphological transformation and the α-SMA and PC Ⅲ expressions of HSCs in vitro and also dramatically prevented the proliferation of HSCs in vitro. Such effects were remarkably different from those of RGD or M6R CONCLUSION： The new compound, RGD-M6P, which has a dramatic effect on primary cultured HSCs in vitro, can inhibit the transformation of HSCs in culture caused by TGFβ1, suppresses the expression of PCIII and decreases proliferation rate of HSC. RGD-M6P can be applied as a selective drug carrier targeting at HSCs, which may be a new approach to the prevention and treatment of liver fibrosis.

关键词： RGD Mannose-6-phosphate Hepatic stellate cell Liver fibrosis

Adaptive Output-feedback Regulation for Nonlinear Delayed Systems Using Neural Network

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International Journal of Automation and computing 2008年第1期5卷 103-108页

作者： wei-sheng chen Jun-Min Li Department of Applied Mathematics,Xidian University,Xi′an 710071,PRC Department of Applied Mathematics Xidian University Xi’an PRC

A novel adaptive neural network （NN） output-feedback regulation algorithm for a class of nonlinear time-varying timedelay systems is proposed. Both the designed observer and controller are independent of time delay. Different from the existing results, where the upper bounding functions of time-delay terms are assumed to be known, we only use an NN to compensate for all unknown upper bounding functions without that assumption. The proposed design method is proved to be able to guarantee semi-global uniform ultimate boundedness of all the signals in the closed system, and the system output is proved to converge to a small neighborhood of the origin. The simulation results verify the effectiveness of the control scheme.

关键词： Adaptive neural network (NN) output-feedback nonlinear time-delay systems backstepping

Syntheses of(C_8H_8)Ln(C_9H_7)·(THF)_2(Ln=Pr,Nd)and crystal structure of(C_8H_8)Pr(C_9H_7)·(THF)_2

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Chinese Journal of Chemistry 1992年第4期10卷 331-336页

作者： WEN,Ke JIN,Zhong-sheng wei,Ge-cheng chen,Wen-Qi Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022 Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022

This paper reports two lanthanide complexes of formula (C_9H_7)Ln(C_8H_8)·(THF)_2 where Ln is Pr or Nd,C_9H_7 is indenyl,and C_8H_8 is cyclooctatetraene (COT).The complexes were prepared by the reaction of LnCl_3 with K(C_9H_7) and K_2(C_8H_8) in THF.(C_9H_7)Pr(C_8H_8)·(THF)_2 crystallizes in THF at - 15℃ in the monoclinic space group P2_1:with unit cell dimensions a=8.446(0),b=10.083(2), c=13.407(3),β=105.48(1)°,V=1100.43(35)~3,Dc=1.52g/cm^3 and Z=*** final R value is 0.033,R_w value is 0.030,*** (C_9H_7)Pr(C_8H_8)·(THF)_2 a five-membered ring centroid of C_9H_7,the C_8H_8 ring centroid and the two oxygen atoms from the two THF molecules form a distorted tetrahedral geometry around the metal.

关键词： Syntheses of C8H8)Pr C8H8)Ln C9H7 THF Nd