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Search Results: 1 - 10 of 34391 matches for " Fangyun Lu "
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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
Suggestion of EFS-small satellite system for impending earthquake forecast
Zuji Qiang,Ainai Ma,Fangyun Chen,Junrong Zhang,Laixing Lin,Zhenlin Lu
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02884670
Abstract: Besides, radiometers of some other microwave frequencies are also included so as to make the small satellite system useful for observation of atmosphere, soil and crops. The platform construction and the altitude control system of the satellites suitable to the sweeping radiometer antennas are stressfully implemented. The orbit of the satellites in the system is well designed so that any place in the world could be observed twice a day in accordance with the optical small satellite system.
Suggestion of EFS-small satellite system for impending earthquake forecast

Zuji Qiang,Ainai Ma,Fangyun Chen,Junrong Zhang,Laixing Lin,Zhenlin Lu,

科学通报(英文版) , 2000,
Abstract: In the IAF Congress ’92 a multiple small satellite Earth observation system was put forward with sensors of visible and infrared spectrums. The system could shorten the revisiting period so that any place on the world could be observed twice a day. Now we extend the idea to the microwave remote sensing satellite system. The main purpose of the system is the impending forecast of earthquakes. According to the theory and long-time concrete practice of Qiang Zuji through the observation of temperature increase of the low layer of atmosphere and its moving trend caused by some sorts of radiation and gases released from Earth interior, an impending strong earthquake could be predicted in time. As the temperature increase is detected by thermo-infrared spectrum sensors on the meteorological satellites, the observation may be sometimes obstructed by cloud or rain. In the suggested system, mm-wave radiometers are used and those obstructions could be generally overcome. Besides, radiometers of some other microwave frequencies are also included so as to make the small satellite system useful for observation of atmosphere, soil and crops. The platform construction and the altitude control system of the satellites suitable to the sweeping radiometer antennas are stressfully implemented. The orbit of the satellites in the system is well designed so that any place in the world could be observed twice a day in accordance with the optical small satellite system.
Bone marrow mesenchymal stem cells from leukemia patients inhibit growth and apoptosis in serum-deprived K562 cells
Zhaohui Wei, Naiyao Chen, Hongxing Guo, Xueming Wang, Fangyun Xu, Qian Ren, ShiHong Lu, Bin Liu, Lei Zhang, Hui Zhao
Journal of Experimental & Clinical Cancer Research , 2009, DOI: 10.1186/1756-9966-28-141
Abstract: K562 cells were cocultured with leukemic MSCs under serum deprivation. Cell Counting Kit-8 (CCK-8), PI staining, Annexin V/PI binding and FACS assays were used to investigate cell proliferation, cell cycle status, and apoptosis of K562 cells cultures in the presence or absence of 10% serum. Western blotting was used to determine the levels of Akt, phosphorylated Akt (p-Akt), the BCL-2 family member Bad, and phosphorylated Bad (p-Bad) proteins in K562 cells after coculturing with MSCs. The effects of LY294002 (a specific inhibitor of PI3K) on protein expression were also determined.K562 cell proliferation was inhibited by coculture with MSCs and the dominant cell cycle was the G0-G1 phase. The proportion of apoptotic K562 cells was decreased and the levels of p-Akt and p-Bad were upregulated after exposing K562 cells to MSCs. However, when LY294002 was used, p-Akt and p-Bad proteins inK562 cells showed a significant reduction, while no distinct variation was seen in the nonphosphorylated Akt and Bad protein levels.Leukemic MSCs can inhibit K562 cell expansion and modulate the cell cycle to a state of relative quiescence. This allows the K562 cells to endure adverse conditions such as serum starvation. The PI3K-Akt-Bad signaling pathway may be involved in this antiapoptotic process via phosphorylation of the Akt and Bad proteins. Blocking MSC-induced transduction of the PI3K-Akt-Bad pathway may be a potential strategy for a targeted therapy to combat leukemia.Bone marrow is not only the source of leukemic cells, but is also the primary site of leukemia relapse [1]. For these reasons, the hematopoietic microenvironment (HM) of the bone marrow plays a crucial role in the development and progression of leukemia. Variations in the HM may influence the biological behaviors of leukemia cells; for example, induction of resistance to chemotherapy drugs by hypoxia [2] is now known to involve many components. One important HM component is the bone marrow mesenchymal stem cell (
RESEARCH ON DYNAMIC FRACTURE BEHAVIORS OF STANSTEAD GRANITE
Stanstead花岗岩动态断裂性能

CHEN Rong,GUO Xian,LU Fangyun,XIA Kaiwen,
陈荣
,郭弦,卢芳云,夏开文

岩石力学与工程学报 , 2010,
Abstract: 采用一种新的方法研究Stanstead花岗岩的动态断裂性能,包括起裂韧度、断裂能、传播韧度和裂纹传播速度。该方法采用分离式霍普金森压杆加载的带预制裂纹的半圆盘三点弯试样,同时采用激光位移计监测试样的裂纹面张开位移。在动态力平衡的条件下,起裂韧度由准静态公式计算得到。通过裂纹面张开位移数据推算出2个碎片的残余动能,从而计算出平均传播断裂能和传播韧度。裂纹传播平均速度由黏接在试样上的一系列裂缝计测量得到。试验结果表明,该花岗岩的起裂韧度和传播韧度都与加载速率有关,传播韧度大于起裂韧度,传播韧度随着裂纹传播速度的提高而提高。通过裂纹传播速度和传播韧度的关系拟合得到材料的止裂韧度及裂纹传播极限速度。得到的Stanstead花岗岩与Laurentian花岗岩结果对比表明,Stanstead花岗岩颗粒较大,起裂、止裂韧度较小;Laurentian花岗岩颗粒较小,传播韧度较小,裂纹传播极限速度较大,裂纹容易传播。
STUDY ON REGULATION OF STRESS WAVE PROPAGATION IN ROCKMASS WITH COMPOUND STRUCTURES
应力波在有地下复合结构的岩石介质中传播规律研究

Li Huanqiu,Lu Fangyun,Wu Xiangyun,Zhao Yuxiang,Ren Huiqi,
李欢秋
,卢芳云,吴祥云,赵玉祥,任辉启

岩石力学与工程学报 , 2003,
Abstract: The compound structures are of clear superiority in resisting dynamic loading and can absorb more shock energy than ordinary structure. Based on the test results by blasting simulation equipment with diameter of 2.5m and the calculations by dynamic finite element method,the stress wave propagation in rockmass with underground compound circle structure surrounded by the soft backfill and the interaction between the stress wave and compound structures are studied. The regulations of the stress wave propagation in rockmass with the underground compound structure are obtained.
在分离式Hopkinson拉杆实验中确定临界实验条件的经验方法
曹雷, 文学军, 卢芳云, 覃金贵, 陈荣
CAO Lei
, WEN Xuejun, LU Fangyun, QIN Jingui, CHEN Rong

- , 2015, DOI: 10.11887/j.cn.201501018
Abstract: 在分离式Hopkinson拉杆实验中,常常需要获得试样在经历一个拉力脉冲拉断情况下的最低应变率,而在分离式Hopkinson拉杆装置中确定对应最低应变率的发射压力需要进行多次尝试性实验。为了更好地解决这一问题,提出一种简单的经验方法,可以通过一次拉断的实验结果计算出一个拉力脉冲拉断试样需要的最小发射压力及相应的应变率,进一步可以预测不同发射压力下的应变率。对4种铝合金试样进行拉伸实验,结果表明,利用提出的经验方法得到的应变率结果与实验结果吻合较好,可以有效地对发射压力和实验应变率进行预估。
In split Hopkinson tensile bar test, it is necessary to obtain the smallest strain rate of the specimen which was fractured by a tensile stress impulse, while determining the corresponding launch pressure of the smallest strain rate needs to conduct many tentative tests. In order to solve this problem well, an empirical method which needs to carry out tensile fracture test only once was proposed to calculate the smallest launch pressure and strain rate to fracture the specimen. The method can further predict the strain rate in different launch pressure. The tensile fracture tests of four kinds of aluminum alloy testify that the proposed method is coincident with the experimental results and it is efficient to evaluate the launch pressure and strain rate.
The Mechanism of Swainsonine Causing Early Pregnancy Abnormal Decidualization and Inducing Abortion by Changing Glycosylation Modification  [PDF]
Yi Wang, Xin Gao, Ming Peng, Yanfei You, Fangyun Shi, Yazhou Guo, Baoyu Zhao, Chenchen Wu
Advances in Reproductive Sciences (ARSci) , 2018, DOI: 10.4236/arsci.2018.63007
Abstract: Locoweed is a poisonous plant that severely harms the development of grass-land and animal husbandry throughout the world. Oxytropis and Astragalus are the Latin names for the poisonous plants commonly known as locoweed. The main toxic substance in these plants is swainsonine. It is a strong inhibitor of lysosomal α-mannosidase I and Golgi body α-mannosidase II, resulting in the accumulation of oligosaccharides and glycoproteins in lysosomes, interfering with the molecular and cellular recognition of glycans, and causing tissue-cell vacuolar degeneration. Livestock shows a series of clinical and pathological symptoms, mainly for the decline of reproductive performance. The effects in dams are abortion, weak fetus, and fetal malformations. The key step in maintaining pregnancy in dams is early endometrial decidualization, because reproductive hormones, decidual cell apoptosis, endoplasmic reticulum (ER) stress, and other immune factors are negatively affected by swainsonine. This article addresses the modifications that occur through glycan processing and glycosylation resulting in the change of post-translational modification of the protein and the activity of the glycoprotein, and then direct and indirect mechanisms of ER stress, apoptosis, reproductive hormones, immune factors, and cell cycle and other pathways. Our aim is to find new methods of prevention and treatment of swainsonine poisoning in grassland animals.
Routing-Aware Clustering Algorithms for Two-Tiered Sensor Networks
Ataul Bari,Fangyun Luo,Arunita Jaekel,Subir Bandyopadhyay
International Journal of Distributed Sensor Networks , 2011, DOI: 10.1155/2011/797916
Abstract: In hierarchical two-tiered sensor networks, higher-powered relay nodes can be used as cluster heads for designing scalable sensor networks. It has been shown that, in such networks, the assignment of sensor nodes to clusters plays an important role in determining the lifetime of the network. In this paper, we have proposed two routing-aware, distributed algorithms for assigning sensor nodes to clusters in two-tiered networks. The first heuristic assumes that all relay nodes, acting as cluster heads, send their data directly to the base station. The second heuristic relaxes this assumption and is to be used with any network where each relay node uses a multihop route to send its data to the base station. Unlike conventional clustering algorithms, our approaches take into consideration the routing scheme used by the relay nodes, and attempt to balance the energy dissipation of the nodes. We have compared the results of our distributed approaches with the optimal solutions obtained using an integer linear program (ILP) formulation, as well as existing techniques, based on heuristics. The results indicate that our approaches, on average, can produce results that are close to the optimal solutions and consistently outperform existing heuristics. 1. Introduction Sensor nodes are tiny, low-powered, and multifunctional devices operated by lightweight batteries. A network of sensor nodes performs tasks through the collaborative efforts of a large number (hundreds or even thousands) of sensor nodes that are densely deployed within the sensing area [1]. Data from each sensor node are gathered at a central entity, often called the base station [1, 2]. Replacing or recharging the batteries of sensor nodes is usually not feasible, so that a sensor network becomes nonfunctional when the batteries in a “sufficient” number of nodes are depleted. The lifetime of a sensor network is a measure of the duration, from the time the network is deployed, to the time it becomes nonfunctional. The limited transmission range and the battery power of sensor nodes affect the scalability and the lifetime of sensor networks. As a consequence, energy conservation in a sensor network to maximize its lifetime is a major research topic. Recently, some special nodes, known as relay nodes (also called gateway nodes [3] and application nodes [4]), have been used to design sensor networks with increased lifetime. The sensor nodes in such a network are organized in clusters. Each cluster is assigned a relay node acting as its cluster head, defining a two-tier hierarchical sensor network [4, 5],
Some classes of rational functions and related Banach spaces
R. M. Dudley,Sergiy Sidenko,Zuoqin Wang,Fangyun Yang
Mathematics , 2007,
Abstract: For positive integers d, r, and M, we consider the class of rational functions on real d-dimensional space whose denominators are products of at most r functions of the form 1+Q(x) where each Q is a quadratic form with eigenvalues bounded above by M and below by 1/M. Each numerator is a monic monomial of the same degree as the corresponding denominator. Then we form the Banach space of countable linear combinations of such rational functions with absolutely summable coefficients, normed by the infimum of sums of absolute values of the coefficients. We show that for rational functions whose denominators are rth powers of a specific 1+Q, or differences of two such rational functions with the same numerator, the norm is achieved by and only by the obvious combination of one or two functions respectively. We also find bounds for coefficients in partial-fraction decompositions of some specific rational functions, which in some cases are quite sharp.
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