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Analytical solution for SH wave propagating through a graded plate of metamaterial

Jinfeng ZHAO, Yongdong PAN, Zheng ZHONG

《机械工程前沿（英文）》 2011年 第6卷 第3期   页码 301-307 doi: 10.1007/s11465-011-0238-7

摘要：

A physical model for the shear horizontal (SH) wave propagating from left-handed material (LHM) through a graded or transition layer to right-handed material (RHM) has been proposed in this paper. After the comparison of the basic wave equations of the electromagnetic, longitudinal, and SH waves, it is found that they take similar differential form. The analytical solutions have been found for power law, hyperbolic, and polynomial profiles. Numerical waveforms of the amplitude and phase of the displacement are obtained for the corresponding profiles. It is found that the waveforms are symmetric for the power law and hyperbolic profiles, and that the waveform for the polynomial profile is shifted and non-symmetric. The shift along with the anti-symmetric profile may provide a way to monitor the wave behavior of the metamaterials.

关键词： left-handed material (LHM)     metamaterial     shear horizontal (SH) wave    

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基于色散可调超构表面的宽带低剖面天线研究综述 Review Articles

Wei E. I. LIU, Zhi Ning CHEN, Xianming QING

《信息与电子工程前沿（英文）》 2020年 第21卷 第1期   页码 27-38 doi: 10.1631/FITEE.1900473

摘要： 超构表面支持传播导波和表面波，并表现出新颖的色散特性。通过调控其独特的色散特性、设置特殊的边界条件以及选用合适的激励机制，低剖面的超构表面天线也能激励起多个邻近的谐振模式以实现宽带定向辐射。本文首先介绍3类典型宽带低剖面色散可调超构表面天线及其工作原理，接着详细综述色散可调超构表面天线技术的研究进展，重点讨论小型化、圆极化、波束扫描等应用设计。这种新近发展的色散可调超构表面技术，不仅能为宽带低剖面天线设计提供解决方案，更显示其在新型天线技术研发中的巨大潜力。

关键词： 超构表面天线；色散调控；复合左右手色散特性；导波；表面波；宽带；低剖面    

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Drug-coated balloon-only strategy for percutaneous coronary intervention of left main coronary artery

《医学前沿（英文）》 2023年 第17卷 第1期   页码 75-84 doi: 10.1007/s11684-022-0950-1

摘要： This retrospective single-center registry study included all consecutive patients who underwent percutaneous coronary intervention (PCI) for a de novo left main coronary artery lesion using drug coated-balloon (DCB)-only strategy between August 2011 and December 2018. To best of our knowledge, no previous studies of DCB-only strategy of treating de novo left main coronary artery disease, exist. The primary endpoint was major adverse cardiovascular events (MACEs) including cardiac death, non-fatal myocardial infarction, and target lesion revascularization (TLR). The cohort was divided into two groups depending on weather the lesion preparation was done according to the international consensus group guidelines. Sixty-six patients (mean age 75±8.6, 72% male), 52% of whom had acute coronary syndrome, underwent left main PCI with the DCB-only strategy. No procedural mortality and no acute closures of the treated left main occurred. At 12 months, MACE and TLR occurred in 24% and 6% of the whole cohort, respectively. If the lesion preparation was done according to the guidelines, the MACE and TLR rates were 21.2% and 1.9%. Left main PCI with the DCB only-strategy is safe leading to acceptable MACE and low TLR rates at one year, if the lesion preparation is done according to the guidelines.

关键词： drug-coated balloon     left main     high bleeding risk     predilatation     calcifield lesion     percutaneous coronary intervention    

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Incremental value of contrast echocardiography in the diagnosis of left ventricular noncompaction

null

《医学前沿（英文）》 2016年 第10卷 第4期   页码 499-506 doi: 10.1007/s11684-016-0473-8

摘要：

Contrast echocardiography with left ventricular opacification (LVO) improves the definition of endocardium in two-dimensional echocardiography (2DE). This study was aimed to determine whether LVO offered added diagnostic value in noncompaction of left ventricular myocardium (NCVM). A total of 85 patients (40±20 years, 54 males) with suspected NCVM were subjected to transthoracic 2DE and LVO, and 40 healthy volunteers were examined with 2DE and assigned as control subjects. The location of NCVM, the thickness ratio of noncompacted to compacted myocardium (NCR), and the cavity size and ejection fraction of LV were quantified. Results revealed that NCVM was mainly located in the LV medium (53.2%), apical (46.2%) segments, and lateral wall (39.8%). The NCR obtained through LVO was greater than that detected through 2DE (4.2±1.3 vs. 3.3±1.2, P<0.001), and higher inter-correlations and less intra- and inter-observer variabilities were determined in the former than in the latter. The NCVM detection rates were also increased from 63.5% via 2DE to 83.5% via LVO and 89.4% via 2DE combined with LVO (2DE+ LVO) (P = 0.0004). The LV cavity size was greater and the LV ejection fraction (LVEF) was lower in the NCVM patients than in the control group (P<0.01). In the NCVM group, the LV cavity size was higher and the LVEF was lower in LVO than in 2DE (P<0.01). In conclusion, contrast echocardiography contributes significant sensitivity and reproducibility to routine transthoracic echocardiography in NCVM diagnosis. Therefore, this technique should be clinically performed to diagnose suspected NCVM.

关键词： echocardiography     left ventricular noncompaction cardiomyopathy     echo contrast media    

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Challenges and opportunities in improving left ventricular remodelling and clinical outcome following

《医学前沿（英文）》 2021年 第15卷 第3期   页码 416-437 doi: 10.1007/s11684-021-0852-7

摘要： Over the last half century, surgical aortic valve replacement (SAVR) has evolved to offer a durable and efficient valve haemodynamically, with low procedural complications that allows favourable remodelling of left ventricular (LV) structure and function. The latter has become more challenging among elderly patients, particularly following trans-catheter aortic valve implantation (TAVI). Precise understanding of myocardial adaptation to pressure and volume overloading and its responses to valve surgery requires comprehensive assessments from aortic valve energy loss, valvular-vascular impedance to myocardial activation, force-velocity relationship, and myocardial strain. LV hypertrophy and myocardial fibrosis remains as the structural and morphological focus in this endeavour. Early intervention in asymptomatic aortic stenosis or regurgitation along with individualised management of hypertension and atrial fibrillation is likely to improve patient outcome. Physiological pacing via the His-Purkinje system for conduction abnormalities, further reduction in para-valvular aortic regurgitation along with therapy of angiotensin receptor blockade will improve patient outcome by facilitating hypertrophy regression, LV coordinate contraction, and global vascular function. TAVI leaflet thromboses require anticoagulation while impaired access to coronary ostia risks future TAVI-in-TAVI or coronary interventions. Until comparable long-term durability and the resolution of TAVI related complications become available, SAVR remains the first choice for lower risk younger patients.

关键词： surgical aortic valve replacement     trans-catheter aortic valve implantation     left ventricular hypertrophy and fibrosis     myocardial force-velocity relationship     His-Purkinje pacing     renin-angiotensin system inhibitors     coronary access impairment    

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Evaluation of potential failure of rock slope at the left abutment of Jinsha River Bridge by model test

Zhiming ZHAO, Xihua WANG

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 332-340 doi: 10.1007/s11709-013-0206-x

摘要： Jinsha River Bridge is located on Tiger Leaping Gorge town, China. The left bank slope composes of moderately thick layer of slate overlain by schistose basalt, and where rocks are controlled by two sets of joint planes. To evaluate the stability of the rock slope under bridge foundation, model test and calculation model based on the geological parameters and the slope stability was simulated and analyzed using Universal Distinct Element Code (UDEC) and Finite Element Mehod (FEM). According to model test, failure mainly initiated at the toe with shear movement along the joint planes, eventually resulting in the sliding along the slope surface and formation of tension crack at the crest of the model. This result coincide with the UDEC model, which shows that slope surface will produce loosening damage and slipping expected along the joint planes under different loading conditions. Moreover, the result of FEM analysis indicates that the rock mass under the main pier has potential shear failure region. So, the bridge foundation should be strengthened to prevent the slope failure under external forces.

关键词： slope stability     strength properties     model test     numerical analysis    

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cannulation of superior vena cava for a hemodialysis patient with an original dysfunctional catheter on the left

null

《医学前沿（英文）》 2017年 第11卷 第3期   页码 445-448 doi: 10.1007/s11684-017-0520-0

摘要：

Establishing a long-term vascular access in patients exhibiting vascular access exhaustion is challenging. In this study, we reported a case of a direct catheterization in the superior vena cava of a hemodialysis patient with vascular access exhaustion and original dysfunctional catheter inserted via the left internal jugular vein. The direct catheterization was performed with cuffed tunnel catheter (CUFF) and guided by digital subtraction angiography (DSA) and multidetector computed tomography venography (MDCTV). The DSA and MDCTV results revealed an occlusion in the right innominate vein and thromboses in the left innominate, right internal jugular, subclavian, and femoral veins. The distal end of the superior vena cava was localized clearly by the original CUFF under DSA. Directed at the distal end of the superior vena cava, a 0.5-cm secondary puncture was introduced below the lateral head of the sternocleidomastoid muscle via the right neck area. This study is one of the few reports regarding direct catheterization of CUFF via the superior vena cava of a patient with vascular access exhaustion and CUFF dysfunction on the left internal jugular vein. We believe that our study can provide a new alternative for inserting central venous catheter for such patient.

关键词： superior vena cava     intervention     vascular access exhaustion     catheterization     tunneled cuffed hemodialysis catheter    

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Assessment of global and regional left ventricular twist and displacement in anterior myocardial infarction

Wei HAN MM, Ming-Xing XIE MD, Qing LV MD, Xin-Fang WANG MD, Li ZHANG MM,

《医学前沿（英文）》 2010年 第4卷 第1期   页码 71-76 doi: 10.1007/s11684-010-0006-9

摘要： The recent development of 2-dimensional strain (2D strain) imaging can provide a powerful alternative for assessing left ventricular (LV) torsion. This study was conducted to evaluate the global and regional left ventricular twist by 2D strain in patients with anterior wall myocardial infarction (AMI). A total of 55 AMI patients were divided into two groups according to their ejection fraction (EF) values (group A: LVEF≥50%; group B: LVEF<50%), and 35 normal people served as the control group. Using 2-dimensional strain software, global and regional LV rotation and displacement were obtained at two planes. Compared with the control group, patients of group A showed reduced peak LV twist of the anterior and anterior-septal wall (9.26±1.89 10.74±2.67; 9.71±1.71 11.36±2.29, both <0.05), but the radial displacement and global twist were maintained (>0.05). Differently, regional and global LV twist and radial displacement in patients of group B deceased significantly, especially in the anterior and anterior-septal wall, as compared with patients in the control or group A (both <0.05). Moreover, a strong correlation was noted between peak twist and radial displacement; the twist-displacement loop was markedly distorted in patients of group B. This study demonstrated that 2D strain has a potential ability for quantification of left ventricular global and segment twist and radial displacement in patients with coronary artery disease.

关键词： echocardiography     twist     two-dimensional strain imaging     coronary artery disease    

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Liquid metal material genome: Initiation of a new research track towards discovery of advanced energy

Lei WANG, Jing LIU

《能源前沿（英文）》 2013年 第7卷 第3期   页码 317-332 doi: 10.1007/s11708-013-0271-9

摘要： As the basis of modern industry, the roles materials play are becoming increasingly vital in this day and age. With many superior physical properties over conventional fluids, the low melting point liquid metal material, especially room-temperature liquid metal, is recently found to be uniquely useful in a wide variety of emerging areas from energy, electronics to medical sciences. However, with the coming enormous utilization of such materials, serious issues also arise which urgently need to be addressed. A biggest concern to impede the large scale application of room-temperature liquid metal technologies is that there is currently a strong shortage of the materials and species available to meet the tough requirements such as cost, melting point, electrical and thermal conductivity, etc. Inspired by the Material Genome Initiative as issued in 2011 by the United States of America, a more specific and focused project initiative was proposed in this paper—the liquid metal material genome aimed to discover advanced new functional alloys with low melting point so as to fulfill various increasing needs. The basic schemes and road map for this new research program, which is expected to have a worldwide significance, were outlined. The theoretical strategies and experimental methods in the research and development of liquid metal material genome were introduced. Particularly, the calculation of phase diagram (CALPHAD) approach as a highly effective way for material design was discussed. Further, the first-principles (FP) calculation was suggested to combine with the statistical thermodynamics to calculate the thermodynamic functions so as to enrich the CALPHAD database of liquid metals. When the experimental data are too scarce to perform a regular treatment, the combination of FP calculation, cluster variation method (CVM) or molecular dynamics (MD), and CALPHAD, referred to as the mixed FP-CVM-CALPHAD method can be a promising way to solve the problem. Except for the theoretical strategies, several parallel processing experimental methods were also analyzed, which can help improve the efficiency of finding new liquid metal materials and reducing the cost. The liquid metal material genome proposal as initiated in this paper will accelerate the process of finding and utilization of new functional materials.

关键词： liquid metal material genome     energy material     material discovery     advanced material     room-temperature liquid alloy     thermodynamics     phase diagram    

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Robust topology optimization of multi-material lattice structures under material and load uncertainties

Yu-Chin CHAN, Kohei SHINTANI, Wei CHEN

《机械工程前沿（英文）》 2019年 第14卷 第2期   页码 141-152 doi: 10.1007/s11465-019-0531-4

摘要： Enabled by advancements in multi-material additive manufacturing, lightweight lattice structures consisting of networks of periodic unit cells have gained popularity due to their extraordinary performance and wide array of functions. This work proposes a density-based robust topology optimization method for meso- or macro-scale multi-material lattice structures under any combination of material and load uncertainties. The method utilizes a new generalized material interpolation scheme for an arbitrary number of materials, and employs univariate dimension reduction and Gauss-type quadrature to quantify and propagate uncertainty. By formulating the objective function as a weighted sum of the mean and standard deviation of compliance, the tradeoff between optimality and robustness can be studied and controlled. Examples of a cantilever beam lattice structure under various material and load uncertainty cases exhibit the efficiency and flexibility of the approach. The accuracy of univariate dimension reduction is validated by comparing the results to the Monte Carlo approach.

关键词： robust topology optimization     lattice structures     multi-material     material uncertainty     load uncertainty     univariate dimension reduction    

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Prognostic value of fasting glucose on the risk of heart failure and left ventricular systolic dysfunction

Hui Wang, Yang Zhang, Zhujun Shen, Ligang Fang, Zhenyu Liu, Shuyang Zhang

《医学前沿（英文）》 2021年 第15卷 第1期   页码 70-78 doi: 10.1007/s11684-020-0749-x

摘要： Recent studies have shown that acute blood glucose elevation in patients with ST-segment elevation myocardial infarction (STEMI) suggests a poor prognosis. To investigate the effect of fasting blood glucose (FBG) on the risk of heart failure (HF) and left ventricular systolic dysfunction (LVSD) in non-diabetic patients undergoing primary percutaneous coronary intervention (PCI) for acute STEMI, we retrospectively recruited consecutive non-diabetic patients who underwent primary PCI for STEMI in our hospital from February 2003 to March 2015. The patients were divided into two groups according to the FBG level. A total of 623 patients were recruited with an age of 61.3±12.9 years, of whom 514 (82.5%) were male. The HF risk (odds ratio 3.401, 95% confidence interval (CI) 2.144–5.395, <0.001) was significantly increased in patients with elevated FBG than those with normal FBG. Elevated FBG was also independently related to LVSD (β 1.513, 95%CI 1.282–1.785, <0.001) in a multiple logistics regression analysis. In conclusion, elevated FBG was independently associated with 30-day HF and LVSD risk in non-diabetic patients undergoing primary PCI for STEMI.

关键词： myocardial infarction     percutaneous coronary intervention     diabetes mellitus     fasting glucose     heart failure    

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Contemporary coronary artery bypass grafting

null

《医学前沿（英文）》 2014年 第8卷 第4期   页码 395-398 doi: 10.1007/s11684-014-0374-7

摘要：

Current evidence clearly demonstrates that coronary artery bypass grafting (CABG) remains the “gold standard” treatment for most patients with multivessel and left main stem disease. This article summarizes the relevant evidence basis demonstrating that CABG, in comparison to stenting, reduces mortality and subsequent myocardial infarction and the need for repeat revascularization. The article also describes the evidence basis to support the use of more arterial grafts during CABG and the current role of off-pump CABG.

关键词： coronary artery bypass grafting (CABG)     coronary artery disease     left main     arterial grafts     internal mammary artery     off-pump CABG    

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工程材料研究中科学问题的思考

于翘

《中国工程科学》 1999年 第1卷 第3期   页码 1-4

摘要：

在不少场合下，航天用工程材料处在极端条件下工作，这就对材料提出许多特殊的要求，虽然国内外有一定的研究积累，但对更精确的模型和符合特定材料的损伤的状态方程，有待深一步研究。如高级弹头再入时气动加热和粒子云侵蚀以及两者耦合效应引起弹头防护材料增大后退量的问题；空中垃圾和微流星的高速碰撞对航天器的威胁；特别是核爆和激光武器对材料的损伤和破坏，实质上是辐射引起的热击波层裂破坏，这些都属于超高速碰撞对材料的响应问题。天线罩材料、吸波材料、红外隐身材料、电磁屏蔽材料都是具有不同波长电磁波的电磁功能材料，它们对固体介质的穿透、吸收、反射等会产生响应，不同的电磁功能材料，其宏观性能的物理参量不同，但有几个参量是通用的，如介电常数、磁导率和损耗角正切，搞清这些参量与材料微观结构的关系，可以为材料设计和材料创新提供科学依据。

关键词： 天线罩材料     吸波材料     红外隐身材料     电磁兼容材料    

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A novel approach to minimizing material loss for computer numerical control flank-regrinding of worn

《机械工程前沿（英文）》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0757-z

摘要： Flanks of end mills are prone to wear in a long machining process. Regrinding is widely used in workshops to restore the flank to an original-like state. However, the traditional method involves material waste by trial and error and dramatically decreases the potential regrinding. Moreover, over-cut would happen to the flutes of worn cutters in the regrinding processes because of improper wheel path. This study presented a new approach to planning the wheel path for regrinding worn end mills to minimize material loss and recover the over-cut. In planning, a scaling method was developed to determine the maximum size of the new cutter according to the similarity of cutter shapes before and after regrinding. Then, the wheel path is first generated by envelope theory to regrind the worn area with a four-axis computer numerical control grinder according to the new size of cutters. Moreover, a second regrinding strategy is applied to recover the flute shape over-cut in the first grinding. Finally, the proposed method is verified by an experiment. Results showed that the proposed approach could save 25% of cutter material compared with the traditional method and ensure at least three regrinding times. This work effectively provides a general regrinding solution for the worn flank with maximum material-saving and regrinding period.

关键词： flank-regrinding     worn end mill     wheel position and orientation     material loss     over-cut    

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A MATLAB code for the material-field series-expansion topology optimization method

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 607-622 doi: 10.1007/s11465-021-0637-3

摘要： This paper presents a MATLAB implementation of the material-field series-expansion (MFSE) topo-logy optimization method. The MFSE method uses a bounded material field with specified spatial correlation to represent the structural topology. With the series-expansion method for bounded fields, this material field is described with the characteristic base functions and the corresponding coefficients. Compared with the conventional density-based method, the MFSE method decouples the topological description and the finite element discretization, and greatly reduces the number of design variables after dimensionality reduction. Other features of this method include inherent control on structural topological complexity, crisp structural boundary description, mesh independence, and being free from the checkerboard pattern. With the focus on the implementation of the MFSE method, the present MATLAB code uses the maximum stiffness optimization problems solved with a gradient-based optimizer as examples. The MATLAB code consists of three parts, namely, the main program and two subroutines (one for aggregating the optimization constraints and the other about the method of moving asymptotes optimizer). The implementation of the code and its extensions to topology optimization problems with multiple load cases and passive elements are discussed in detail. The code is intended for researchers who are interested in this method and want to get started with it quickly. It can also be used as a basis for handling complex engineering optimization problems by combining the MFSE topology optimization method with non-gradient optimization algorithms without sensitivity information because only a few design variables are required to describe relatively complex structural topology and smooth structural boundaries using the MFSE method.

关键词： MATLAB implementation     topology optimization     material-field series-expansion method     bounded material field     dimensionality reduction    

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标题 作者 时间 类型 操作

Analytical solution for SH wave propagating through a graded plate of metamaterial

Jinfeng ZHAO, Yongdong PAN, Zheng ZHONG

期刊论文

基于色散可调超构表面的宽带低剖面天线研究综述

Wei E. I. LIU, Zhi Ning CHEN, Xianming QING

期刊论文

Drug-coated balloon-only strategy for percutaneous coronary intervention of left main coronary artery

期刊论文

Incremental value of contrast echocardiography in the diagnosis of left ventricular noncompaction

null

期刊论文

Challenges and opportunities in improving left ventricular remodelling and clinical outcome following

期刊论文

Evaluation of potential failure of rock slope at the left abutment of Jinsha River Bridge by model test

Zhiming ZHAO, Xihua WANG

期刊论文

cannulation of superior vena cava for a hemodialysis patient with an original dysfunctional catheter on the left

null

期刊论文

Assessment of global and regional left ventricular twist and displacement in anterior myocardial infarction

Wei HAN MM, Ming-Xing XIE MD, Qing LV MD, Xin-Fang WANG MD, Li ZHANG MM,

期刊论文

Liquid metal material genome: Initiation of a new research track towards discovery of advanced energy

Lei WANG, Jing LIU

期刊论文

Robust topology optimization of multi-material lattice structures under material and load uncertainties

Yu-Chin CHAN, Kohei SHINTANI, Wei CHEN

期刊论文

Prognostic value of fasting glucose on the risk of heart failure and left ventricular systolic dysfunction

Hui Wang, Yang Zhang, Zhujun Shen, Ligang Fang, Zhenyu Liu, Shuyang Zhang

期刊论文

Contemporary coronary artery bypass grafting

null

期刊论文

工程材料研究中科学问题的思考

于翘

期刊论文

A novel approach to minimizing material loss for computer numerical control flank-regrinding of worn

期刊论文

A MATLAB code for the material-field series-expansion topology optimization method

期刊论文