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A survey of photon mapping state-of-the-art research and future challenges

Chun-meng KANG,Lu WAN,Yan-ning XU,Xiang-xu MENG

《信息与电子工程前沿（英文）》 2016年第17卷第3期页码 185-199 doi: 10.1631/FITEE.1500251

摘要： Global illumination is the core part of photo-realistic rendering. The photon mapping algorithm is an effective method for computing global illumination with its obvious advantage of caustic and color bleeding rendering. It is an active research field that has been developed over the past two decades. The deficiency of precise details and efficient rendering are still the main challenges of photon mapping. This report reviews recent work and classifies it into a set of categories including radiance estimation, photon relaxation, photon tracing, progressive photon mapping, and parallel methods. The goals of our report are giving readers an overall introduction to photon mapping and motivating further research to address the limitations of existing methods.

关键词： Global illumination Photon mapping Radiance estimation Photon relaxation Progressive photon mapping

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Carbon dots-based fluorescence sensor for two-photon imaging of pH in diabetic mice

《化学科学与工程前沿（英文）》 2023年第17卷第3期页码 298-306 doi: 10.1007/s11705-022-2212-9

摘要： Herein, a reversible pH fluorescent sensor was developed using caffeic acid as the precursor by one-step solvothermal synthesis method. The carbon dots-based sensor (CA-CDs) exhibited pH-dependent increase in fluorescence intensity and showed linear relationship in the range of pH 6.60 and 8.00. Notably, the fluorescence sensor has a reversible response to pH change. Finally, the CA-CDs has been successfully applied for two-photon imaging of the pH in liver and kidney of diabetic mice. Imaging results showed that the pH value in kidney of diabetic mice was lower than that of the normal mice, while the pH value in liver of diabetic mice was almost the same as that of the normal mice. The present study provides a simple analytical method for pH detection suitable for in vivo.

关键词： carbon dots two-photon imaging pH diabetic mice

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Deformation control criterion of shield tunnel under lateral relaxation of soft soil

《结构与土木工程前沿（英文）》 2023年第17卷第5期页码 780-795 doi: 10.1007/s11709-023-0944-3

摘要： Metro shield tunnels under the lateral relaxation of soil (LRS) are susceptible to significant lateral deformations, which jeopardizes the structural safety and waterproofing. However, deformation control standards for such situations have not been clearly defined. Therefore, based on a specific case, a model test is conducted to realize the LRS of a shield tunnel in a sandy stratum to reveal its effect on segment liners. Subsequently, a deformation control criterion is established. The LRS is simulated by linearly reducing the loads applied to the lateral sides of the segment structure. During lateral unloading, the lateral earth pressure coefficient on the segment decreases almost exponentially, and the structural deformation is characterized by horizontal expansion at the arch haunches and vertical shrinkage at the arch vault and arch bottom. Based on the mechanical pattern of the segment structure and the acoustic emission, the deformation response of a segment can be classified into three stages: elastic and quasi-elastic, damage, and rapid deformation development. For a shield tunnel with a diameter of approximately 6 m and under the lateral relaxation of sandy soil, when the ellipticity of the segment is less than 2.71%, reinforcement measures are not required. However, the segment deformation must be controlled when the ellipticity is 2.71% to 3.12%; in this regard, an ellipticity of 3% can be used as a benchmark in similar engineering projects.

关键词： shield tunnel lateral relaxation of soil deformation control criterion of segment structure model test

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Finding buckling points for nonlinear structures by dynamic relaxation scheme

Mohammad REZAIEE-PAJAND, Hossein ESTIRI

《结构与土木工程前沿（英文）》 2020年第14卷第1期页码 23-61 doi: 10.1007/s11709-019-0549-z

摘要： Dynamic Relaxation Method (DRM) is an explicit approach for solving the simultaneous systems of equations. In this tactic, the fictitious mass and damping are added to the static governing equations, and an artificial dynamic system is constructed. By using DRM for nonlinear analysis, the structural static equilibrium path is obtained. This outcome is extremely valuable, since it leads to the behavior of structures. Among the finding related to the structural static path are the critical and buckling points for nonlinear structures. In this paper, a new way for calculating the load factor is proposed by setting the external work zero. Mixing the dynamic relaxation scheme with external work technique has not been formulated so far. In all incremental-iterative methods, the load factor increment sign should be determinated by extra calculations. This sign leads to increase or decrease of the load increment. It is worth emphasizing that sign of the load factor increment changes at the load limit points. Therefore, the sign determinations are required in the common work control methods. These disadvantages are eliminated in the proposed algorithm. In fact, the suggested load factor depends only on the Dynamic Relaxation (DR) fictitious parameters. Besides, all DR calculations are performed via vector operation. Moreover, the load factor is calculated only by one formula, and it has the same relation in the all solution processes. In contrast to the arc length techniques, which requires the sign determined, the proposed scheme does not need any sign finding. It is shown that author’s technique is quicker than the other dynamic relaxation strategies. To prove the capability and efficiency of the presented scheme, several numerical tests are performed. The results indicate that the suggested approach can trace the complex structural static paths, even in the snap-back and snap-through parts.

关键词： load factor external work dynamic relaxation static equilibrium path large displacement

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Nonlinear analysis of cable structures using the dynamic relaxation method

Mohammad REZAIEE-PAJAND, Mohammad MOHAMMADI-KHATAMI

《结构与土木工程前沿（英文）》 2021年第15卷第1期页码 253-274 doi: 10.1007/s11709-020-0639-y

摘要： The analysis of cable structures is one of the most challenging problems for civil and mechanical engineers. Because they have highly nonlinear behavior, it is difficult to find solutions to these problems. Thus far, different assumptions and methods have been proposed to solve such structures. The dynamic relaxation method (DRM) is an explicit procedure for analyzing these types of structures. To utilize this scheme, investigators have suggested various stiffness matrices for a cable element. In this study, the efficiency and suitability of six well-known proposed matrices are assessed using the DRM. To achieve this goal, 16 numerical examples and two criteria, namely, the number of iterations and the analysis time, are employed. Based on a comprehensive comparison, the methods are ranked according to the two criteria. The numerical findings clearly reveal the best techniques. Moreover, a variety of benchmark problems are suggested by the authors for future studies of cable structures.

关键词： nonlinear analysis cable structure stiffness matrix dynamic relaxation method

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A fast and accurate dynamic relaxation scheme

Mohammad REZAIEE-PAJAND, Mohammad MOHAMMADI-KHATAMI

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 176-189 doi: 10.1007/s11709-018-0486-2

摘要： Dynamic relaxation method (DRM) is one of the suitable numerical procedures for nonlinear structural analysis. Adding the fictitious inertia and damping forces to the static equation, and turning it to the dynamic system, are the basis of this technique. Proper selection of the DRM artificial factors leads to the better convergence rate and efficient solutions. This study aims to increase the numerical stability, and to decrease the analysis time. To fulfil this objective, the reduction rate of analysis error for consecutive iterations is minimized. Based on this formulation, a new time step is found for the viscous dynamic relaxation. After combining this novel relationship with the other DRM factors, various geometrical nonlinear structures, such as, trusses, frames and shells are analyzed. The obtained results verify the efficiency of authors’ scheme.

关键词： viscous dynamic relaxation time step displacement error geometric nonlinear analysis

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波粒二象性理论的若干问题

黄志洵

《中国工程科学》 2002年第4卷第1期页码 54-63

摘要：

论述了光波和物质波的波粒二象性理论的发展，讨论了该理论的存留问题。认为光子的静质量和光子的内部结构仍是科学中的关键性疑点。指出，虽然波粒二象性成立的前提是波长足够小，但在现有理论中却提不出一条清晰的界线。讨论了光波和电磁波是物质还是物质属性的问题。提出了对de Broglie波超光速相速的疑问。分析表明，如何建立电磁脉冲的粒子形象的问题仍需解决。此外，探讨了当电磁脉冲以超光速传播时相对论是否受破坏。最后，讨论了消失波的粒子性和虚光子问题。

关键词：光子光波物质波波粒二象性孤子电磁脉冲超光速消失波虚光子

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The stress relaxation of cement clinkers under high temperature

Xiufang WANG,Yiwang BAO,Xiaogen LIU,Yan QIU

《机械工程前沿（英文）》 2015年第10卷第4期页码 413-417 doi: 10.1007/s11465-015-0357-7

摘要：

The energy consumption of crushing is directly affected by the mechanical properties of cement materials. This research provides a theoretical proof for the mechanism of the stress relaxation of cement clinkers under high temperature. Compression stress relaxation under various high temperatures is discussed using a specially developed load cell, which can measure stress and displacement under high temperatures inside an autoclave. The cell shows that stress relaxation dramatically increases and that the remaining stress rapidly decreases with an increase in temperature. Mechanical experiments are conducted under various temperatures during the cooling process to study the changes in the grinding resistance of the cement clinker with temperature. The effects of high temperature on the load-displacement curve, compressive strength, and elastic modulus of cement clinkers are systematically studied. Results show that the hardening phenomenon of the clinker becomes apparent with a decrease in temperature and that post-peak behaviors manifest characteristics of the transformation from plasticity to brittleness. The elastic modulus and compressive strength of cement clinkers increase with a decrease in temperature. The elastic modulus increases greatly when the temperature is lower than 1000 °C. The compressive strength of clinkers increases by 73.4% when the temperature drops from 1100 to 800 °C.

关键词： stress relaxation high temperature cement clinker compression elastic modulus

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Synthesis and characterization of 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles with two-photon fluorescence

ZHU Xiaoqin, QIAN Ying, LU Zhifeng

《化学科学与工程前沿（英文）》 2007年第1卷第4期页码 381-384 doi: 10.1007/s11705-007-0069-6

摘要： Four novel 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles that exhibit strong two-photon absorption and enhanced two-photon excited fluorescence were designed and synthesized based on push-core-pull-core-push molecules built from embedding electron-transporting 1,3,4-oxadiazole in aromatic conjugated system through Wittig-Horner reaction. Their chemical structures were determined to show trans-vinylene character according to infrared (IR) and H nuclear magnetic resonance (NMR) spectra. A very effective energy transfer from the excited units to the ?-conjugated bridging unit can enhance the two-photon absorption and two-photon fluorescence.

关键词： 2-arylvinyl trans-vinylene character effective fluorescence push-core-pull-core-push

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中微子研究新进展

黄志洵

《中国工程科学》 2002年第4卷第10期页码 90-93

摘要：

自从前苏联的V. Lubimov（1980年）和瑞士苏黎世大学的W. Kundig（1986年）发表了关于中微子质量的研究以来，进一步的工作已在日本等国展开；现在有一批实验室在进行中微子研究。文章论述了两个关键问题，即光子与中微子的相似性和令人感兴趣的超光速中微子理论。

关键词：中微子超光速快子光子

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Hypoplastic constitutive modeling of wetting deformation of weathered rockfill materials

Erich BAUER, Zhongzhi FU, Sihong LIU,

《结构与土木工程前沿（英文）》 2010年第4卷第1期页码 78-91 doi: 10.1007/s11709-010-0011-8

摘要： The wetting deformation of weathered rockfill materials has been attracting growing attention from both engineers and scientists. The importance of realistic predictions of wetting deformations for high earth and rockfill dams is a strong motivation to establish a suitable constitutive model. Recently, the hypoplastic constitutive model by Gudehus and Bauer was extended by introducing solid hardness depending on the state of weathering. The extended model takes into account the influence of the current density, the effective stress state, the rate of deformation, and the time dependent process of degradation of the solid hardness. In the present paper, the performance of this model is evaluated by comparing numerical simulations with experiments obtained from a water sensitive rockfill material. In particular, triaxial compression paths and creep deformation under deviatoric stress states are considered. Finally, the constitutive model proposed is used to study the influence of a degradation of the solid hardness on the long term behavior of a hypothetical fill dam.

关键词： rockfill dams weathered granular materials hypoplasticity solid hardness creep stress relaxation

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血浆代谢组学结合超微弱发光表征早期2型糖尿病的中医证型 Article

何敏, 孙濛濛, Slavik Koval, Roeland Van Wijk, Thomas Hankemeier, Jan Van der Greef, Eduard P.A. Van Wijk, 王梅

《工程（英文）》 2019年第5卷第5期页码 916-923 doi: 10.1016/j.eng.2019.03.011

摘要：

2型糖尿病（T2DM）的患病率在全球范围内呈迅速上升趋势。因通用干预措施收效甚微，所以疾病研究的重点已经转向个性化策略，特别是疾病的早期阶段的个性化策略。中医基于系统观建立并结合了个性化策略，提高了我们对个性化诊断的认识。从系统生物学的角度，例如将代谢组学与其他系统性诊断方法（如超微弱发光）相结合，可提高对个性化诊断的理解，同时为此类个性化诊疗策略提供生化相关物质基础。在本研究中，我们研究了44名处于2型糖尿病前期的受试者的血浆代谢组学，探讨了基于以下中医亚型进行疾病早期分型的可行性：气阴两虚、气阴两虚挟痰湿、气阴两虚挟血瘀。此外，通过血浆代谢组学和超微弱发光在中医亚分型方面的关系，获得体内生化参数与体外表征参数的关联性信息，从而尝试对疾病亚型分类及判断有更深一步的阐释。结果表明，血浆代谢物的主成分分析揭示了从中医角度划分的2型糖尿病前期不同亚型之间的差异性。对于3种2型糖尿病前期亚型，相对含量较高的脂质（如胆固醇酯和甘油三酯）是鉴别其中之二的重要元素，并且可能与较高的心血管疾病风险相关。血浆代谢组学数据表明，血脂谱是超微弱发光在2型糖尿病亚型分型中收集的重要组成部分。结果表明，2型糖尿病前期的不同中医亚型之间存在代谢差异，可通过血浆代谢物分析来区分这些亚型，血浆代谢组学为系统性超微弱发光体表测量提供了生化参数相关依据。

关键词： 2型糖尿病血浆代谢物疾病亚型超微弱发光相关性网络

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光的本性

范良藻,冯劲松

《中国工程科学》 2007年第9卷第2期页码 58-67

摘要：

文献［１］提出每一个光量子hf都由个数不同的N（λ）个单光子组成的假设，并在已公布的氢光谱的数据中找出和不同hf的光量子相对应的N（λ）值和单光子的质量。文章报告了进一步发现光量子hf的波长与N（λ）的乘积在某些特定条件下是一个不变量ζ＝N（λ）λ^［２］这一特征现象，从而破解了波粒二象性近百年之迷端：所谓光量子的波长不过是相邻两个单光子的间距，而频率f则是在单位时间内通过空间坐标某处单光子的个数，并用单光子的数形结构导出所有惯性系中光速c＝λf都是不变的结论。狭义相对论的光速不变原理，不再是一个

关键词：光量子波粒二象性原子光谱狭义相对论

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双向中继传输中基于半定松弛的非相干检测 Regular Papers-Research Articles

Chan-fei WANG, Ji-ai HE, Wei-fang WANG, Ya-mei XU

《信息与电子工程前沿（英文）》 2019年第20卷第9期页码 1259-1265 doi: 10.1631/FITEE.1800096

摘要：提出一种双向中继传输广播阶段高性能非相干传输方案，即不需要信道估计的多符号差分检测算法。在下行阶段首次引入基于广义似然比检验的多符号差分检测（GLRT-MSDD）。进一步转换GLRT-MSDD，得到基于半定松弛的多符号差分检测（SDR-MSDD），此转化过程降低了算法实现的复杂度。性能分析和仿真结果表明，在双向中继传输中，所提SDR-MSDD方法以合理复杂度得到接近于GLRT-MSDD方法的误码性能。

关键词：多符号差分检测；广义似然比检验；半定松弛；双向中继传输

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物理光学的若干进展

黄志洵

《中国工程科学》 2006年第8卷第2期页码 18-29

摘要：

就物理光学方面的一系列理论和实验研究，如Goos-Hänchen位移、FTIR现象、负折射率、太赫超光速实验、光子静质量测量等做了评述和讨论。指出近年来的研究显示了消失波现象的重要性，例如消失波可造成超光速传播，且常有新方法和新测量结果；介绍了物理光学在相关领域的技术创新和应用实例；讨论了光子有静止质量的可能性及光频标准和光频测量的历史和新的进展。

关键词：物理光学负波速负折射率 GH位移消失波光子静质量