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Digitalized Mirror Array and Its Application in Large Telescope:Principle and Case Studies

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Communications in Theoretical Physics 2009年第10期52卷 750-760页

作者： chen Ying-Tian ZHANG Yang HU Sen Ho Tso-Hsiu Boon Ham lim chen sin lim Kok Keong Chong Boon Kok Tan University of Science and Technology of China Department of Astronomy and Applied Physics Hefei 230026 China University of Science and Technology of China Department of Mathematics Hefei 230026 China Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190 China University of Tunku Abdul Rahman Faculty of Engineering and Science Selangor Malaysia

In this article, we report the principle and conceptual design of a fundamentally different technology in fabricating high precision aberration free optical devices. The tip-tilt of facet in a mirror array is produced by digitally controlled line-tilts of rows and columns. It has not only provided a cost-effective designing methodology in optical physics but also led to a much finer precision of 1 mili arc sec or less. As examples of the application of the proposed digitalised optics, two case studies have been given： a 10 m Schmidt telescope （off-axis） and an 8 m Cassegrain telescope （on-axis）.

关键词： tip-tilting line-tilting Schmidt telescope aberration correction cassegrain telescope

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3D打印中的生物可接受性参数

世界建筑 2024年第1期 54-55页

作者：艾瑞尔·陈阿尤布·拉齐母卓尔(译) 丹麦皇家建筑艺术学院不详

随着城市的发展,人类对地球上有限的空间和资源的争夺不断加剧,许多野生动物因此失去家园甚至失去生命。我们有必要在城市中引入更多植被及其所包含的微生物,以重建一个更多元的生态系统,并通过调节温度和CO_(2)等条件,增强城市环境的... 详细信息

随着城市的发展,人类对地球上有限的空间和资源的争夺不断加剧,许多野生动物因此失去家园甚至失去生命。我们有必要在城市中引入更多植被及其所包含的微生物,以重建一个更多元的生态系统,并通过调节温度和CO_(2)等条件,增强城市环境的可持续性和韧性。生物可接受性设计是将生物多样性融入现有城市基础设施的一种解决方案,尤其适用于高密度城市环境和与自然界隔绝的室内环境。利用3D打印技术的高精度,我们可以设计出特定的复杂几何形状,起到促进生物生长的作用。

关键词：城市基础设施生态系统室内环境生物多样性生物生长野生动物可持续性

Complete Solution of Sun Tracking for Heliostat

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Communications in Theoretical Physics 2006年第1期45卷 165-166页

作者： chen Ying-Tian lim Boon-Han lim Chern-sing Department of Astronomy and Applied Physics University of Science and Technology of China Hefei 230026 China

A general solution of sun tracking for an arbitrarily oriented heliostat towards an arbitrarily located target on the earth is published. With the most general form of solar tracking formulae, it is seen that the used azimuthelevation, spinning-elevation tracking formulae etc. are the special cases of it. The possibilities of utilizing the general solution and its significance in solar energy engineering are discussed.

关键词： solar tracking azimuth-elevation spinning-elevation optical aberration heliostat

Energetics and conserved quantity of an axially moving string undergoing three-dimensional nonlinear vibration

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Acta Mechanica sinica 2008年第2期24卷 215-221页

作者： Liqun chen C. W. lim Hu Ding Department of Mechanics Shanghai University Shanghai 200444 China Department of Construction and Building City University of Hong Kong Hong Kong China Shanghai Institute of Applied Mathematics and Mechanics Shanghai 200072 China

Nonlinear three-dimensional vibration of axially moving strings is investigated in the view of energetics. The governing equation is derived from the Eulerian equation of motion of a continuum for axially accelerating strings. The time-rate of the total mechanical energy associated with the vibration is calculated for the string with its ends moving in a prescribed way. For a string moving in a constant axial speed and constrained by two fixed ends, a conserved quantity is proved to remain unchanged during three-dimensional vibration, while the string energy is not conserved. An approximate conserved quantity is derived from the conserved quantity in the neighborhood of the straight equilibrium configuration. The approximate conserved quantity is applied to verify the Lyapunov stability of the straight equilibrium configuration. Numerical simulations are performed for a rubber string and a steel string. The results demonstrate the variation of the total mechanical energy and the invariance of the conserved quantity.

关键词： Nonlinear free vibration Axial movingstring Energetics Conserved quantity Stability

Mechanical joint performances of friction self-piercing riveted carbon fiber reinforced polymer and AZ31B Mg alloy

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Journal of Magnesium and Alloys 2022年第12期10卷 3367-3379页

作者： Yuan Li Yong Chae lim Jian chen Jiheon Jun Zhili Feng Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA

Carbon fiber reinforced polymer(CFRP) and AZ31B Mg alloy were joined by the friction self-piercing riveting(F-SPR) with different steel rivet shank sizes. With the increase of rivet shank size, lap shear fracture load and mechanical interlock distance increased. Ultrafine grains were formed at the joint in AZ31B as a result of dynamic recrystallization, which contributed to the higher hardness. Fatigue life of the CFRP-AZ31B joint was studied at various peak loads of 0.5, 1, 2, and 3 kN and compared with the resistance spot welded AZ31B-AZ31B from the open literature. The fatigue performance was better at higher peak load(>2 kN) and comparable to that of resistance spot welding of AZ31B to AZ31B at lower peak loads(<1 kN). From fractography, the crack initiation for lower peak load(<1 kN) case was observed at the fretting positions on the top and bottom surfaces of AZ31B sheet. When peak load was increased, fretting between the rivet and the top of AZ31B became more dominant to initiate a crack during fatigue testing.

关键词： Friction self-piercing riveting Magnesium alloy Carbon fiber reinforced polymer Dynamic recrystallization Fatigue life Crack initiation

Electrogastrography associated with symptomatic changes after prokinetic drug treatment for functional dyspepsia

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World Journal of Gastroenterology 2012年第41期18卷 5948-5956页

作者： Hyun Chul lim Sang In Lee Jiande DZ chen Hyojin Park Department of Internal Medicine Yonsei University College of MedicineSeoul 120-752South Korea Division of Gastroenterology Department of Internal MedicineUniversity of Texas Medical BranchGalvestonTX 77555United States

AIM:To evaluate the effect of prokinetic drugs on electrogastrography(EGG) parameters according to symptomatic changes in patients with functional dyspepsia(FD).METHODS:Seventy-four patients with FD were prospectively enrolled in this study between December 2006 and December *** surveyed the patients using a questionnaire on dyspeptic symptoms before and after an 8-wk course of prokinetic drug *** also measured cutaneous pre-prandial and postprandial EGG recordings including percentage of gastric waves(normogastria,bradygastria,tachygastria),dominant frequency(DF),dominant power(DP),dominant frequency instability coefficient(DFIC),dominant power instability coefficient(DPIC),and the ratio of post-prandial to fasting in DP before and after the 8-wk course of prokinetic drug ***:Fifty-two patients(70%) achieved symptomatic improvement after prokinetic drug *** who had normal gastric slow waves showed symptom improvement group after *** DF showed a downward trend in the symptom improvement group,especially in the itopride ***-prandial DP was increased regardless of symptom improvement,especially in the itopride group and mosapride ***-prandial DFIC and DPIC in the symptom improvement group were significantly increased after the *** EGG power ratio was increased after treatment in the symptom improvement group(0.50 ± 0.70 vs 0.93 ± 1.77,P = 0.002),especially in the itopride and levosulpiride ***:Prokinetics could improve the symptoms of FD by regulating gastric myoelectrical activity,and EGG could be a useful tool in evaluating the effects of various prokinetics.

关键词： Electrogastrography Functional dyspepsia Itopride Mosapride Levosulpiride

Unravelling the competitive effect of microstructural features on the fracture toughness and tensile properties of near beta titanium alloys

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Journal of Materials Science & Technology 2022年第2期97卷 101-112页

作者： Yang Liu Samuel C.V.lim chen Ding Aijun Huang Matthew Weyland Department of Materials Science and Engineering Monash UniversityClaytonVIC3800Australia Monash Centre for Additive Manufacturing Monash UniversityNotting HillVIC3168Australia BAOWU Special Metallurgy Co.Ltd. Shanghai200940China Monash Centre for Electron Microscopy Monash UniversityClaytonVIC3800Australia

The competitive effect of microstructural features including primaryα(α_(p)),secondaryα(α_(s)),grain boundaryα(α_(GB)) and β grain size on mechanical properties of a near β Ti alloy were studied with two heat treatment *** relative effect of β grain size and STA(solution treatment and ageing)processing parameters on mechanical properties were quantitatively explored by the application of Taguchi *** results were further explained via correlating microstructure with the fracture toughness and tensile *** was found that large numbers of fine as precipitates and continuous α_(s) played greater roles than other features,resulting in a high strength and very low ductility(<2%)of STA process *** β grain size had a negative correlation with fracture *** the samples prepared by BASCA( β anneal slow cooling and ageing)process,improved ductility and fracture toughness were obtained due to a lower density ofα;precipitates,a basket-weave structure and zigzag morphology of α_(GB).For this heat treatment,an increase in prior β grain size had an observable positive effect on fracture *** contradictory effect of β grain size on fracture toughness found in literature was for the first time *** was shown that the microstructure obtained from different processes after β solution has complex effect on mechanical *** complexity derived from the competition between microstructure features and the overall sum of their effect on fracture toughness and tensile properties.A novel table was proposed to quasi-quantitatively unravel these competitive effects.

关键词： Nearβtitanium alloys Microstructural features Competitive effect Fracture toughness βgrain size effect

Telephone Penetration and Economic Growth in the APEC Region： A Simultaneous Non-Linear GMM Approach

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Frontiers of Economics in China-Selected Publications from Chinese Universities 2012年第3期7卷 339-362页

作者： Eng Kooi lim Zhiqi chen Economic Policy and Enforcement Branch Competition BureauGovernment of CanadaGatineauQC K1A 0C9Canada Department of Economics Carleton UniversityOttawaON K1S 5B6Canada

We examine the contributions of the telecommunications infrastructure to economic growth in the Asia-Pacific Economic Cooperation （APEC） economies during the period from 1982 to 2003 using a modified version＇of the model developed by Roller and Waverman （2001）. Our estimation results show that, consistent with Roller and Waverman （2001）, telecommunication infrastructure has a significant effect on economic growth in the APEC region and that the inclusion of country fixed effects is important for obtaining a more reliable estimate of the growth effect. Moreover, the magnitude of the growth effect is inversely related to the level of telecommunications infrastructure in the APEC economies. While the marginal effect of an increase in telecommunications infrastructure in the APEC region is smaller than that in the OECD countries found ir/Roller and Waverman （2001）, the total contribution of telecommunication infrastructure to economic growth is larger in the former than in the latter.

关键词： APEC growth telecommunications

Advances and applications of CRISPR/Cas-mediated interference in Escherichia coli

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Engineering Microbiology 2024年第1期4卷 55-65页

作者： Xiaohui lim Congqiang Zhang Xixian chen singapore Institute of Food and Biotechnology Innovation(SIFBI) Agency for Science Technology and Research(A∗STAR)31 Biopolis WayLevel 6Nanos BuildingSingapore 138669Singapore

The bacterium Escherichia coli(***)is one of the most widely used chassis microbes employed for the biosynthesis of numerous valuable chemical *** the past decade,the metabolic engineering of *** has undergone significant advances,although further productivity improvements will require extensive genome modification,multi-dimensional regulation,and multiple metabolic-pathway *** this context,clustered regularly interspaced short palindromic repeats(CRISPR),along with CRISPR-associated protein(Cas)and its inactive variant(dCas),have emerged as notable recombination and transcriptional regulation tools that are particularly useful for multiplex metabolic engineering in *** this review,we briefly describe the CRISPR/Cas9 technology in ***,and then summarize the recent advances in CRISPR/dCas9 interference(CRISPRi)systems in ***,particularly the strategies designed to effectively regulate gene repression and overcome retroactivity during ***,we discuss recent applications of the CRISPRi system for enhancing metabolite production in ***,and finally highlight the major challenges and future perspectives of this technology.

关键词： CRISPRi Multiplex Metabolic engineering CRISPR/dCas9 Retroactivity