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Gas–liquid two-phase flow in serpentine microchannel with different wall wettability

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Chinese Journal of Chemical Engineering 2017年第7期25卷 874-881页

作者： Yunlong Zhou he chang Tianyu Qi Energy and Power Engineering College Northeast Dianli University Institute of Energy Environment and Economy Tsinghua University

Gas–liquid flow in serpentine microchannel with different surface properties exhibits drastically different flow behavior. With water and air as working fluids, the method of numerical simulation was adopted in this paper based on CLSVOF(coupled level set and volume of fluid method) multiphase model. After verifying the reasonability of the model through experiment, by changing wall properties and Re number(Rehe influences of contact angle and surface roughness on flow regime and Po number were discussed. Moreover, the difference of pressure drop between curve and straight microchannel was also calculated. Beyond that, the combined effect of curve channel and wall properties on flow resistance was analyzed. This paper finds that wall properties have great influence on gas–liquid flow in microchannels not only on flow regime but also flow characteristics. Meanwhile, the pressure drop in curve microchannels is larger than straight. It is more beneficial for fluid flowing when the straight part of microchannel is hydrophilic smooth wall and curve part is hydrophobic with large roughness.

关键词： Serpentine microchannel Computational fluid dynamics Gas-liquid flow Microfluidics

Numerical investigation of the seismic response of a UHV composite bypass switch retrofitted with wire rope isolators

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Earthquake Engineering and Engineering Vibration 2021年第1期20卷 275-290页

作者： Yang Zhenyu Xie Qiang he chang Xue Songtao Department of Civil Engineering Tongji UniversityShanghai 200092China

An ultra-high voltage(UHV)composite bypass switch(BPS)faces increasing seismic challenges when UHV projects extend to high seismic intensity *** UHV composite BPS still generates excessive stress at the bottom section although hollow composite insulators with high flexural strength are *** the standard retrofitting strategy by using stiffer supports cannot reduce stress responses,wire rope isolation is *** optimal design of isolation considers both stress and displacement responses since the slenderness and composite material of insulators contribute to significant *** results show that properly designed isolation can significantly reduce stress without excessive displacement responses.A larger radius configuration helps to improve the applicability of small stiffness isolators under high *** the isolation still cannot satisfy the requirement,smaller stiffness isolators with a larger radius,or isolators with increased loops and smaller radius,can be introduced to gain better energy dissipation capacity and effectiveness in response ***,a three-step design procedure is proposed to increase the damping force but fix the rotational stiffness of ***,the application of wire rope isolation can be extended to UHV composite BPS with a low natural frequency,but conductors with enough redundancy should be used.

关键词： UHV composite bypass switch seismic analysis seismic performance upgrading wire rope isolator

Molecular characteristics and stages of chronic hepatitis B virus infection

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World Journal of Gastroenterology 2009年第25期15卷 3099-3105页

作者： Ying-Hui Shi chang-he Shi Department of Microbiology Centers for Disease Control and Prevention of Qingdao Qingdao 266034 Shandong Province China Department of hepatitis Qingdao Infectious Disease Hospital Qingdao 266033 Shandong Province China

hepatitis B virus (HBV) is a common viral pathogen that causes a substantial health burden worldwide. Remarkable progress has been made in our understanding of the natural stages of chronic HBV infection. A dynamic balance between viral replication and host immune response is pivotal to the pathogenesis of liver disease. Knowledge of the HBV genome organization and replication cycle can unravel HBV genotypes and molecular variants, which contribute to the heterogeneity in outcome of chronic HBV infection. Most HBV infections are spontaneously resolved in immunocompetent adults, whereas they become chronic in most neonates and infants at a great risk of developing complications such as cirrhosis and hepatocellular carcinoma (HCC). Those with chronic HBV infection may present in one of the four phases of infection: immune tolerance, immune clearance [hepatitis B eantigen (HBeAg)-positive chronic hepatitis B (CHB)], inactive carrier state, and reactivation (HBeAg-negative CHB). Understanding the dynamic nature of chronic HBV infection is crucial in the management of HBV carriers. Long-term monitoring and optimal timing of antiviral therapy for chronic HBV infection help to prevent progression of HBV-related liver disease to its later stage, particularly in patients with higher risk markers of HCC, such as serum DNA concentration, HBeAg status, serum aminotransferase, HBV genotypes, and pre-core or core mutants.

关键词： hepatitis B virus Pathology Immune tolerance Immune clearance Inactive hepatitis B surface antigen carriers Reactivation T-cell response Cytokines

Mechatronic Design of a Synergetic Upper Limb Exoskeletal Robot and Wrench-based Assistive Control

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Journal of Bionic Engineering 2018年第2期15卷 247-259页

作者： Lei he Caihua Xiong Kai Liu Jian Huang chang he Wenbin Chen School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China School of Automation Huazhong University of Science and Technology Wuhan 430074 China

Upper limb exoskeletal rehabilitation robots are required to assist patients＇ arms to perform activities of daily living according to their motion intentions. In this paper, we address two questions： how to design an exoskeletal robot which can mechanically reconstruct functional movements using only a few actuators and how to establish wrench-based assistive control. We first show that the mechanism replicating the synergic feature of the human upper limb can be designed in a recursive manner, meaning that the entire robot can be constructed from two basic mechanical units. Next, we illustrate that the assistive control for the synergetic exoskeletal robot can be transformed into an optimization problem and a Riemannian metric is proposed to generate anthropomorphic reaching movements according to contact forces and torques. Finally, experiments are carried out to verify the functionality of the proposed theory.

关键词： upper limb exoskeletal robot postural synergy wrench based assistive control

Study on （2＋1）-Dimensional Nizhnik-Novikov-Veselov Equation by Using Extended Mapping Approach

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Communications in Theoretical Physics 2006年第1X期46卷 10-14页

作者： XU chang-Zhi he Bao-Gang Department of Physics Jinhua Education College Jinhua 321000 China

Extended mapping approach is introduced to solve （2＋1）-dimensional Nizhnik-Novikov Veselov equation. A new type of variable separation solutions is derived with arbitrary functions in the model. Based on this excitation, rich localized structures such as multi-lump soliton and ring soliton are revealed by selecting the arbitrary function appropriately.

关键词： extended mapping approach (2+1)-dimensional Nizhnik-Novikov-Veselov equation new localized excitation

A general solution for Stokes flow and its application to the problem of a rigid plate translating in a fluid

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Acta Mechanica Sinica 2015年第1期31卷 32-44页

作者： Xiang-Yu Li Si-Cong Ren Qi-chang he School of Mechanics and Engineering Southwest Jiaotong University School of Mechanical Engineering Southwest Jiaotong University Universit'e Paris-Est Laboratoire Mod'elisation et Simulation Multi Echelle UMR 8208 CNRS 5 Boulevard Descartes77454 Marne-la-Vall'ee France

A general solution for 3D Stokes flow is given which is different from, and more compact than the exist ing ones and more compact than them in that it involves only two scalar harmonic functions. The general solution deduced is combined with the potential theory method to study the Stokes flow induced by a rigid plate of arbitrary shape trans lating along the direction normal to it in an unbounded fluid. The boundary integral equation governing this problem is derived. When the plate is elliptic, exact analytical results are obtained not only for the drag force but also for the ve locity distributions. These results include and complete the ones available for a circular plate. Numerical examples are provided to illustrate the main results for circular and ellip tic plates. In particular, the elliptic eccentricity of a plate is shown to exhibit significant influences.

关键词： Stokes flow 3D general solutions Potentialtheory method Circular plate Elliptic plate

A New Infeasible-Interior-Point Algorithm for Linear Programming over Symmetric Cones

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Acta Mathematicae Applicatae Sinica 2017年第3期33卷 771-788页

作者： chang-he LIU You-lin SHANG Ping HAN School of Mathematics and Statistics Henan University of Science and Technology College of Mathematics and System Science Shandong University of Science and Technology

In this paper we present an infeasible-interior-point algorithm, based on a new wide neighbourhood N（ t1, t2, η）, for linear programming over symmetric cones. We treat the classical Newton direction as the sum of two other directions. We prove that if these two directions are equipped with different and appropriate step sizes, then the new algorithm has a polynomial convergence for the commutative class of search directions. In particular, the complexity bound is O（r1.5 log ε-1） for the Nesterov-Todd （NT） direction, and O（r2 log ε-1） for the xs and sx directions, where r is the rank of the associated Euclidean Jordan algebra and ε 〉 0 is the required precision. If starting with a feasible point （x0, y0, s0） in N（t1, t2, η）, the complexity bound is O（ √ r log ε-1） for the NT direction, and O（r log ε-1） for the xs and sx directions. When the NT search direction is used, we get the best complexity bound of wide neighborhood interior-point algorithm for linear programming over symmetric cones.

关键词： symmetric cone Euclidean Jordan algebra interior-point methods linear programming polynomial complexity

Upper Yellow River air concentrations of organochlorine pesticides estimated from tree bark, and their relationship with socioeconomic indices

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Journal of Environmental Sciences 2014年第3期26卷 593-600页

作者： chang he Jun Jin Bailin Xiang Ying Wang Zhaohui Ma College of Life and Environmental Sciences Minzu University of China

Organochlorine pesticide （OCP） concentrations in tree bark from the upper Yellow River region were determined. Total OCP concentrations ranged from 2.7 to 82 ng/g dw, with a mean of 20 ng/g dw. Concentrations of total （E） DDTs （0.49-37 ng/g dw）, HCHs （0.55-4.5 ng/g dw）, and HCB （0.1-1.0 ng/g dw） were much higher than the other OCPs and accounted for 89% of the YOCP concentrations. p,p＇-DDT was the dominant member of the DDT pesticide group and [5-HCH was the dominant HCH isomer. The p,p＇-DDT/p,p＇-DDE and ct-HCH/y-HCH ratios suggested that there were recent DDT and y-HCH releases. OCP concentrations in the air were estimated from the tree bark, and the estimated median 3ZDDTs, EHCHs, and HCB concentrations in the air were 0.09, 0.14, and 0.024 pg/m3, respectively. The relationship between total OCP concentrations and socioeconomic and natural environment indices were assessed using multiple linear regression analysis, and a regression equation including all these factors was obtained. Population density and tertiary industry were the two dominant factors that appeared to affect OCP concentrations in the upper Yellow River region.

关键词： North-western China organohalogen willow vegetation atmosphere persistent organic pollutants (POPs)

Phase Patterning of Poly(oxime-ester)for Information Encryption by Photo-induced Isomerization

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Chinese Journal of Polymer Science 2024年第10期42卷 1488-1494,I0010页

作者： Yu-Fan Yang Yun Bai Yi-Bao Li chang-Fei he School of Chemistry and Chemical Engineering Gannan Normal UniversityGanzhou341000China

Crystal polymers or liquid crystal elastomers undergo a phase transition that results in a change in the corresponding optical properties,which has the potential to be applied in areas such as information encryption and *** utilization of these materials for patterning purposes requires different phase transition ***,once prepared,altering the phase transition temperature of them presents significant ***,a poly(oxime-ester)(POE)network is developed to achieve high-resolution and multilevel patterning by photo-induced *** as-prepared POE exhibits the ability to transition from an opaque state to a transparent state under temperature stimuli,with the transition temperature and kinetics dependent on UV light exposure ***,complex patterns and information can be encrypted through different selective regional exposure time and decrypted under specific temperature or cooling ***,we illustrate an example of temporal communication,where cooling time or temperature serves as the encoded *** research expands the application scope of advanced encryption materials,showcasing the potential of POE in dynamic information encryption and decryption processes.

关键词： Poly(oxime-ester) Isomerization Phase patterning Information encryption