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Search Results: 1 - 10 of 42723 matches for " Binbin Xu "
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Central Extension of Mapping Class Group via Chekhov-Fock Quantization
Binbin Xu
Mathematics , 2014,
Abstract: The central extension of mapping class groups of punctured surfaces of finite type that arises in Chekhov-Fock quantization is 12 times of the Meyer class plus the Euler classes of the punctures, which agree with the one arising in the Kashaev quantization.
On the Ambartzumian-Pleijel identity in hyperbolic geometry
Xu Binbin
Mathematics , 2014,
Abstract: We describe a hyperbolic version of the Ambartzumian-Pleijel identity. We use this identity to prove the hyperbolic Crofton formula and the hyperbolic isoperimetric inequality. This identity also provides a way to compute the chord length distribution for an ideal polygon in the hyperbolic plane. The analogous results for a maximally symmetric, simply connected, $2$-dimensional Riemannian manifold with constant sectional curvature are given at the end.
Retrieving Soil Water Contents from Soil Temperature Measurements by Using Linear Regression
Qin XU,Binbin ZHOU,
Qin XU
,Binbin ZHOU

大气科学进展 , 2003,
Abstract: A simple linear regression method is developed to retrieve daily averaged soil water content from diurnal variations of soil temperature measured at three or more depths. The method is applied to Oklahoma Mesonet soil temperature data collected at the depths of 5, 10, and 30 cm during 11-20 June 1995. The retrieved bulk soil water contents are compared with direct measurements for one pair of nearly collocated Mesonet and ARM stations and also compared with the retrievals of a previous method at 14 enhanced Oklahoma Mesonet stations. The results show that the current method gives more persistent retrievals than the previous method. The method is also applied to Oklahoma Mesonet soil temperature data collected at the depths of 5, 25, 60, and 75 cm from the Norman site during 20 30 July 1998 and 1-31 July 2000. The retrieved soil water contents are verified by collocated soil water content measurements with rms differences smaller than the soil water observation error (0.05 ma m-a). The retrievals are found to be moderately sensitive to random errors (±0.1 K) in the soil temperature observations and errors in the soil type specifications.
Research of China''s Soil Spectral Line
我国土壤光谱线之研究

Xu Binbin,
徐彬彬

遥感学报 , 1991,
Abstract: The analysis on soil spectral data obtained from the different area of our country shows that exists a soil spectral line in 2-dimension space or multidimension space, but it is not a strictly straight line, it is a belt with certain width. It is not suitable for vegetation analysis with a united soil spectral line in the whole country. The influence of different soil spectral line on plant canopy and greenness assessment was discussed. In addition, the results and physical significance of the principal component analysis on the soil spectral reflectance were described.
A New Resveratrol Trimer from the Roots and Stems of Vitis wenchowensis
Binbin Gu,Yaru Xu,Shan He
Molecules , 2013, DOI: 10.3390/molecules18077486
Abstract: Phytochemical constituents of Vitis wenchowensis were investigated for the first time. A new resveratrol trimer, wenchowenol ( 1), was isolated from the roots and stems of Vitis wenchowensis along with four known stilbenoids 2–5. The structure and relative configuration of 1 were established on the basis of spectral evidence, especially HMBC and NOESY experiments. It showed potent antioxidant activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) radical.
Association between -238 but not -308 polymorphism of Tumor necrosis factor alpha (TNF-alpha)v and unexplained recurrent spontaneous abortion (URSA) in Chinese population
Chunmei Liu, Jing Wang, Sirui Zhou, Binbin Wang, Xu Ma
Reproductive Biology and Endocrinology , 2010, DOI: 10.1186/1477-7827-8-114
Abstract: A cohort of 132 Southern Chinese Han RSA patients and 152 controls constituted the subjects of this study. Two functional polymorphisms -308 and -238 of TNF-alpha were studied by association analysis.lack of association was found in TNF-alpha -308 SNP yet a significant difference was discovered in -238 polymorphism.This study suggested that TNF-alpha may be a risk factor in Chinese RSA patients. However the ethnic differences may also contribute to the results.Recurrent spontaneous abortion (RSA) is defined as three or more consecutive pregnancy losses before 22 gestational weeks or the spontaneous abortion of an embryo/fetus weighing less than 500 g and affecting an estimated 1 of every 100 couples preparing to have children [1]. The diagnosis of RSA undergo multiple tests to detect parental chromosomal anomalies, maternal thrombophilic, endocrine, or immunological disorders, yet it has been estimated that the specific cause of RSA remains unknown in 37%-79% of affected women. Over 50% of the RSA cases are classified as idiopathic unexplained recurrent spontaneous abortion (URSA) [1].Possible candidates include genes regulating the development of increased cellular immunity [2] and altered T helper 1 (Th1)-Th2 balance as well as autoimmune abnormalities, coagulation, angiogenesis, vascular tone, and apoptosis.Successful pregnancy is dependent on maintaining a fine balance between Th1 and Th2 immunity so forth Th1 and Th2 intracellular cytokine expression is supposed to alter in RSA patients. Over expression of Th1 cytokines is thus associated with RSA in several studies [3]. Infiltration by natural killer (NK) cells and activated macrophages were also detected in resorption sites.Produced by Th1 cells, cytokine Tumor necrosis factor alpha (TNF-alpha) is a multifunctional proinflammatory cytokine secreted predominantly by monocytes/macrophages that has effects on lipid metabolism, coagulation, insulin resistance, and endothelial function and was proposed as a candid
Methyl N-hydroxy-N-(2-methylphenyl)carbamate
Binbin Zhang,Yifeng Wang,Kun Dong,Danqian Xu
Acta Crystallographica Section E , 2013, DOI: 10.1107/s1600536813000421
Abstract: There are three independent molecules in the asymmetric unit of the title compound, C9H11NO3, which are connected by O—H...O hydrogen bonds, forming an R33(15) ring. The dihedral angles between the planes of the benzene and amide groups are 75.16 (3), 71.47 (3) and 70.56 (3)°. The hydroxy O atom lies 0.912 (3), 1.172 (2) and 1.339 (2) from the mean plane of the corresponding benzene ring in the three molecules.
A Request Distribution Algorithm for Web Server Cluster
Wei Zhang,Huan Wang,Binbin Yu,Wei Xu
Journal of Networks , 2011, DOI: 10.4304/jnw.6.12.1760-1766
Abstract: With the explosively increasing of web-based applications’ workloads, Web server cluster encounters challenge in response time for requests. Request distribution among servers in web server cluster is the key to address such challenge, especially under heavy workloads. In this paper, we propose a new request distribution algorithm named llac (least load active cache) for load balancing switch in web server cluster. The goal of llac is to improve the cache hit rate and reduce response time. Packets are parsed in IP level, and back-end servers are notified to cache hot files using link change technology, neither changing URL information nor modifying the service program. This avoids switching overhead between user mode and kernel mode. The load balancing switch directly creates connection with the selected server, avoiding migrating connection overhead. This policy estimates the current composited load of each server and selects the server with the least load to serve the request. It also improves the resource utilization of web servers. Experimental results show that llac achieves better performance for web applications than wrr (weight round robin) which is a popular request distribution.
Dynamic Mechanical Properties and Constitutive Relation of an Aluminized Polymer Bonded Explosive at Low Temperatures
Yuliang Lin,Binbin Xu,Rong Chen,Jingui Qin,Fangyun Lu
Shock and Vibration , 2014, DOI: 10.1155/2014/918103
Abstract: Polymer bonded explosives (PBXs) are widely used as energetic fillings in various warheads, which maybe are utilized under extreme environments, such as low or high temperatures. In this paper, the dynamic response of an aluminized polymer bonded explosive was tested at a range of temperatures from ?55°C to ?2°C and a fixed loading strain rate (~700?s?1) with the split Hopkinson pressure bar (SHPB). The PBX tested is aluminized, which contains 76?wt% RDX, 20?wt% aluminum powder, and 4?wt% polymer binder, respectively. The results show that the effect of temperature on the strength of the PBX is obvious at the tested strain rates. Based on the experimental results and prophase studies, a constitutive model was obtained, in which the effect of temperature and strain rate were considered. The modeling curves fit well with the experimental results, not only at low temperature under 0°C, but also at room temperature (20°C). The model may be used to predict the dynamic performances of the PBXs in various environments. 1. Introduction Due to low sensitivity and high detonation performance, the polymer bonded explosives (PBXs) are commonly used as energetic fillings in various weapon systems. In addition, the PBXs feature favorable mechanical and physical properties and can be easily shaped for different warheads. Since the operation circumstances of the weapon systems are complex, the industrial and military technology research institutions require the energetic materials to be workable under extreme environments, such as wide temperature ranges. However, PBXs’ main components are explosive crystal and polymer binder. Due to the fact that the latter can be easily affected by change in temperature, the mechanical properties of PBXs are usually nonlinear and highly temperature dependent. Further research is needed to fully characterize the dynamic mechanical properties of PBX over a wide temperature range, and the constitutive model is required to be developed to predict the dynamic mechanical properties at different temperatures. Some research works on dynamic mechanical properties of PBXs have been done [1–17]. The dynamic and static mechanical properties of PBXs were very different [5]. Furthermore, researchers have paid more attention to the effect of temperature on dynamic mechanical response of PBXs [6–16]. The stress-strain responses of PBX9501 and mock 9501 were tested under different temperatures and strain rates [6]. Gray III et al. used a specially designed SHPB setup to obtain the compression properties of PBX9501 and PBX9502 over a wide range of
Perimeter traffic control strategybased on macroscopic fundamental diagrams
Xu Jianmin, Yan Xiaowen, Ma Yingying, Jing Binbin
- , 2017, DOI: 10.3969/j.issn.1003-7985.2017.04.018
Abstract: A perimeter traffic signal control strategy is proposed based on the macroscopic fundamental diagram theory(MFD)to solve the signal control problem in oversaturated states. First, the MFD of a specific regional network can be derived using VISSIM simulation software. Secondly, the maximum number of cumulative vehicles that the network can accommodate is determined based on the MFD. Then, through monitoring the influx flow, the number of vehicles existing in and exiting from the network, a perimeter traffic control model is proposed to optimize the signal timing of the boundary intersections. Finally, a virtual network simulation model is established and three different kinds of traffic demand are loaded into the network. Simulation results show that after the strategy implementation, the number of vehicles accumulating in the network can be kept near the optimal value, while the number of both entering and exiting vehicles increases significantly and the road network can be maintained at a large capacity. Simultaneously, the queue length at the approach of the border intersections is reasonably controlled and vehicles entering and exiting the network can maintain a more efficient and stable speed. The network performance indices such as the average traffic delay and average number of stops can be improved to a certain degree, thus verifying the effectiveness and feasibility of the perimeter control strategy.
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