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Rigidity of closed submanifolds in a locally symmetric Riemannian manifold

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Applied Mathematics(A Journal of Chinese Universities) 2016年第2期31卷 237-252页

作者： GU Juan-ru LENG yan XU Hong-wei Department of Applied Mathematics Zhejiang University of Technology Hangzhou 310023 China Center of Mathematical Sciences Zhejiang University Hangzhou 310027 China

Let Mn（n ≥ 4） be an oriented closed submanifold with parallel mean curvature in an （n ＋ p）-dimensional locally symmetric Riemannian manifold Nn＋p. We prove that if the sectional curvature of N is positively pinched in [5, 1], and the Ricci curvature of M satisfies a pinching condition, then M is either a totally umbilical submanifold, or δ= 1, and N is of constant curvature. This result generalizes the geometric rigidity theorem due to Xu and Gu [15].

关键词： Submanifold Ejiri rigidity theorem Ricci curvature Mean curvature.

Resonant Peak Splitting for Ballistic Conductance in Two-Dimensional Electron Gas Under Electromagnetic Modulation

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Chinese Physics Letters 2000年第8期17卷 598-600页

作者： WANG ru-Zhi yan Xiao-Hong Department of Physics Xiangtan UniversityXiangtan 411105

By developing a transfer-matrix method,the resonant peaks splitting of ballistic conductance are investigated into the two-dimensional electron gas system with both electric and magnetic modulations of nanoscale *** is found that there exists the n-fold resonant peak splitting for ballistic conductance through n perpendicular magnetic barriers to n electric *** a combination of m magnetic barriers and n electric barriers by increasing the amplitude of electric field,the folds of the splitting would shift from m- to n-1.

关键词： splitting resonant conductance

Intestinal glucagon-like peptide-1:A new player associated with impaired counterregulatory responses to hypoglycaemia in type 1 diabetic mice

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World Journal of Diabetes 2024年第8期15卷 1764-1777页

作者： Fang-Xin Jin yan Wang Min-Ne Li ru-Jiang Li Jun-Tang guo Department of Histology and Embryology Key Laboratory of Universities in Shandong ProvinceShandong Second Medical UniversityWeifang 261053Shandong ProvinceChina Department of Pathological Physiology Shandong Second Medical UniversityWeifang 261053Shandong ProvinceChina

BACKGROUND Impaired hypoglycaemic counterregulation has emerged as a critical concern for diabetic patients who may be hesitant to medically lower their blood glucose levels due to the fear of potential hypoglycaemic ***,the pathogenesis of hypoglycaemic counterregulation is still ***-like peptide-1(GLP-1)and its analogues have been used as adjunctive therapies for type 1 diabetes mellitus(T1DM).The role of GLP-1 in counterregulatory dysfunction during hypoglycaemia in patients with T1DM has not been *** To explore the impact of intestinal GLP-1 on impaired hypoglycaemic counterregulation in type 1 diabetic *** T1DM was induced in C57BL/6J mice using streptozotocin,followed by intraperitoneal insulin injections to create T1DM models with either a single episode of hypoglycaemia or recurrent episodes of hypoglycaemia(DH5).Immunofluorescence,Western blot,and enzyme-linked immunosorbent assay were employed to evaluate the influence of intestinal GLP-1 on the sympathetic-adrenal reflex and glucagon(GCG)*** GLP-1 receptor agonist GLP-1(7-36)or the antagonist exendin(9-39)were infused into the terminal ileum or injected intraperitoneally to further investigate the role of intestinal GLP-1 in hypoglycaemic counterregulation in the model *** The expression levels of intestinal GLP-1 and its receptor(GLP-1R)were significantly increased in DH5 *** instances of excess of intestinal GLP-1 weakens the sympathetic-adrenal reflex,leading to dysfunction of adrenal counterregulation during ***5 mice showed increased pancreaticδ-cell mass,cAMP levels inδcells,and plasma somatostatin concentrations,while cAMP levels in pancreaticαcells and plasma GCG levels ***,GLP-1R expression in islet cells and plasma active GLP-1 levels were significantly increased in the DH5 *** experiments involving terminal ileal infusion and intraperitoneal injection in the model mice demonstra

关键词： Glucagon-like peptide-1 Impaired hypoglycaemic counterregulation Type 1 diabetes Intestine Pancreas

Study on the instantaneous protection reliability of low voltage circuit breakers

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第3期8卷 370-377页

作者： LU Jian-guo DU Tai-hang LUO yan-yan Electrical Apparatus Institute Hebei University of Technology Tianjin 300130 China

This paper outlines the significance of enhancing the instantaneous protection reliability of low voltage circuit breakers and describes their main failure modes. The instantaneous failure mechanism of low voltage circuit breakers was analyzed so that measures to improve instantaneous protection reliability can be determined. Furthermore, the theory of the instantaneous characteristics calibration device for low voltage circuit breakers and the method of eliminating the non-periodic component of test current are given in detail. Finally, the test results are presented.

关键词： Low voltage circuit breakers Instantaneous protection reliability Non-periodic component of current Phase selective closing

Efficient recovery of group-sparse signals with truncated and reweighted l_(2,1)-regularization

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Journal of Systems Engineering and Electronics 2017年第1期28卷 19-26页

作者： yan Zhang Jichang guo Xianguo Li School of Electronic Information Engineering Tianjin University School of Computer and Information Engineering Tianjin Chengjian University School of Electronic and Information Engineering Tianjin Polytechnic University

The l2, 1-norm regularization can efficiently recover group-sparse signals whose non-zero coefficients occur in a few groups. It is well known that the l2, 1-norm regularization based on the classic alternating direction method shows strong stability and robustness in many applications. However, the l2, 1-norm regularization requires more measurements. In order to recover group-sparse signals with a better sparsity-measurement tradeoff, the truncated l2, 1-norm regularization and reweighted l2, 1-norm regularization are proposed for the recovery of group-sparse signals based on the iterative support detection. The proposed algorithms are tested and compared with the l2, 1-norm model on a series of synthetic signals and the Shepp-Logan phantom. Experimental results demonstrate the performance of the proposed algorithms, especially at a low sample rate and high sparsity level. © 1990-2011 Beijing Institute of Aerospace Information.

关键词： Iterative methods Recovery

Entropy optimization based filtering for non-Gaussian stochastic systems

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Science China(Information Sciences) 2017年第12期60卷 33-43页

作者： Bo TIAN yan WANG Lei guo School of Automation Science and Electrical Engineering Beihang University National Key Laboratory on Aircraft Control Technology Beihang University

This paper is concerned with the entropy optimization based filter design for a class of multivariate dynamic stochastic systems with simultaneous presence of non-Gaussian process noise and measurement *** filter consists of time update and measurement update two steps, where the selection of the filter gain in the measurement update equation is a key issue to be addressed. Different from the classic Kalman filter theory, entropy rather than variance is employed as the filtering performance criterion due to the non-Gaussian characteristic of the estimation error. Following the establishment of the relationship between the probability density functions of random noises and estimation error, two kinds of entropy based performance indices are provided. On this basis, the corresponding optimal filter gains are obtained respectively by using the gradient optimization technique. Finally, some numerical simulations are provided to demonstrate the effectiveness of the proposed filtering algorithms.

关键词： non-Gaussian systems joint probability density function(JPDF) quadratic information potential relative entropy optimal filtering

Aging Precipitation Behavior and Mechanical Properties of Inconel 617 Superalloy

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Acta Metallurgica Sinica(English Letters) 2013年第3期26卷 307-312页

作者： yan guo Bohan WANG Shufang HOU Materials Department Xi'an Thermal Power Research Institute Co.Ltd.

Aging precipitation behavior and mechanical properties of Inconel 617 superalloy aged at 760℃ for up to 10000 h were investigated. The results showed that the precipitates of the aged alloy are M23C6 and M6C carbides and γ phase. The carbide particles precipitated both at the grain boundaries and within grains, and the γ phase particles were situated at intragranular sites in the process of aging. The carbide particles were discontinuously dispersed at grain boundaries after aging for 3000 h, while after aged for 5000 h the carbide particles are merged. The precipitates inside grains remained stable even after aging for 10000 h. The hardness was increased for the alloy aged for 300 h up to 3000 h, which was resulted primarily from the precipitation of carbides as discrete particles both at the grain boundaries and inside grains. Small quantity γ precipitates were formed inside grains, to some extent, which contributed to an enhanced hardness. However, a decrease of the hardness was observed after aging for 5000 h. A significant drop in toughness of the alloy aged for 300 h was attributed to the reduction of the bonding interface strength when carbides precipitated at grain boundaries. Thereafter, the toughness decreased slowly with the prolonged aging time. The high temperature tensile properties of the aged alloy are rather stable even aged for 300-3000 h.

关键词： Inconel 617 Superalloy Aging Precipitate Mechanical properties

Three-component reaction for synthesis of functionalized spiro[indoline-3,4'-pyrano[3,2-h]quinolines]

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Chinese Chemical Letters 2016年第4期27卷 575-578页

作者： Rong-guo Shi Chao-guo yan College of Chemistry & Chemical Engineering Yangzhou University

The functionalized spiro[indoline-3,40-pyrano[3,2-h]quinolines] were efficiently prepared in high yields from three-component reaction of 8-hydroxyquinoline, isatins and malononitrile or ethyl cyanoacetate in ethanol ... 详细信息

关键词： Spirooxindole Chromene Isatin Malononitrile Three-component reaction

A rapid modeling method for urban microscale meteorology and its applications

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Science China Earth Sciences 2023年第10期66卷 2224-2238页

作者： Xiaoran guo Chao yan Shiguang MIAO Institute of Urban Meteorology China Meteorological AdministrationBeijing100089China Key Laboratory of Urban Meteorology China Meteorological AdministrationBeijing100089China

This paper introduces a fast urban microscale meteorological model with a horizontal resolution of O(10)m,named URBAN(Urban Rapid&Building-Aware Neighborhood),which is capable of rapid assessment of meteorological fields over key urban areas,including wind speed,air temperature,humidity and thermal comfort index,with the execution time less than10 minutes consuming 1 CPU *** uses a fast wind diagnostic method to construct three-dimensional(3-D)wind fields surrounding complex building clusters with their geometry resolved *** enhance the accuracy of wind reconstruction and the continuity of the initial wind field around irregular buildings,we propose a new parameterization method based on stream functions,which can accurately characterize the influences of complex urban building clusters on the three-dimensional wind *** model can provide various results for the meteorological service of large outdoor activities,including conventional meteorological elements(wind,temperature,humidity,radiation,etc.)and the Universal Thermal Comfort Index,which is derived from the relationship between physiological processes and environmental meteorological *** this paper,URBAN is applied to develop an automatic analysis and forecast system of microscale meteorological elements over the central Beijing region in summer during a large outdoor *** comparing with the half-hourly observations from three auto weather stations(AWSs)in the region,the root-mean-square errors(RMSEs)of the modeled 10-meter-height wind speed,2-meter-height air temperature and humidity are 0.98 m s^(-1),1.37℃and 7.37%,respectively.

关键词： Urban microscale meteorology Wind diagnose Fast simulation Human comfort index Weather service