基于元胞自动机的埃博拉药物配送系统设计

采用元胞自动机模型预测了西非36个地区埃博拉患者的未来人数,针对抗埃博拉病毒药物保质期较短的特点,根据所需药物数量设计出了该药物的二级配送系统,提出了最短时间配送系统、最低成本配送系统2种模型,并进一步阐述了运行效率更为高效的跨国界最低成本配送系统。更多还原     

Combination of interference alignment and beamforming in cellular networks

In this paper, we propose two joint transmit-receive iterative algorithms without the cooperation between different base stations based on the idea of interference alignment (IA) to improve the throughput of relay backhaul links in cellular networks for the case of imperfect channel knowledge,which can be implemented with small changes to existing TD-LTE standards. Unlike the previous interference alignment algorithms’ only reducing the sum interference to the other receivers at the transmitter or the sum received Multi-user interference (MUI) at the receiver, our algorithm shapes the transmission of each data stream at transmitters in order not only to minimize interference to the other users, but also to minimize the interference between different streams objected to the same user, suppressing the MUI and Multi-stream interference (MSI) at receivers. The proposed algorithm I is to maximize the SINR at receivers. But the complexity is relatively high. Algorithm II only needs linear operations and sacrifices a little performance for much lower complexity compared to the Maximize SINR iterative algorithm which needs the inversion operation of matrix. It is also proved that the algorithm converges monotonically. The simulation results show that the techniques have considerable performance gain compared with the previous algorithms. Further research about power allocation is also discussed.     

A new TDOA algorithm based on Taylor series expansion in cellular networks

Time difference of arrival (TDOA) is the positioning technique with the most potential in cellular mobile telecommunication systems. The Taylor series expansion method has been widely used in solving nonlinear equations for its high accuracy and good robustness. However, the performance of the Taylor’s method depends highly on the initial estimation. Therefore, one new algorithm, hybrid optimizing algorithm (HOA) was proposed, which combines the Taylor series expansion method with the steepest decent method. The steepest decent method features fast convergence at the initial iteration and small computation complexity. HOA takes great advantage of both methods. Simulation results show that HOA achieves better performance on positioning accuracy and efficiency. __________ Translated from Journal on Communications, 2007, 28(6): 7–11 [译自: 通信学报]     

Perinatal Obesity Induces Hepatic Growth Restriction with Increased DNA Damage Response,Senescence, and Dysregulated Igf-1-Akt-Foxo1 Signaling in Male Offspring of Obese Mice

Maternal obesity predisposes for hepato-metabolic disorders early in life. However, the underlying mechanisms causing early onset dysfunction of the liver and metabolism remain elusive. Since obesity is associated with subacute chronic inflammation and accelerated aging, we test the hypothesis whether maternal obesity induces aging processes in the developing liver and determines thereby hepatic growth. To this end, maternal obesity was induced with high-fat diet (HFD) in C57BL/6N mice and male offspring were studied at the end of the lactation [postnatal day 21 (P21)]. Maternal obesity induced an obese body composition with metabolic inflammation and a marked hepatic growth restriction in the male offspring at P21. Proteomic and molecular analyses revealed three interrelated mechanisms that might account for the impaired hepatic growth pattern, indicating prematurely induced aging processes: (1) Increased DNA damage response (γH2AX), (2) significant upregulation of hepatocellular senescence markers (Cdnk1a, Cdkn2a); and (3) inhibition of hepatic insulin/insulin-like growth factor (IGF)-1-AKT-p38-FoxO1 signaling with an insufficient proliferative growth response. In conclusion, our murine data demonstrate that perinatal obesity induces an obese body composition in male offspring with hepatic growth restriction through a possible premature hepatic aging that is indicated by a pathologic sequence of inflammation, DNA damage, senescence, and signs of a possibly insufficient regenerative capacity.     

Relations between compliances of inhomogeneities having the same shape but different elastic constants

The contributions of inhomogeneities having the same shape but different elastic constants, to the overall elastic properties are interrelated. The utility of these relations lies, in particular, in the possibility to extend available results for pores or rigid inclusions to inhomogeneities of arbitrary elastic properties. The relations are exact for ellipsoids and approximate for non-ellipsoidal shapes. The constructed approximation also constitutes approximate connection between the first Eshelby’s problem (the eigenstrain problem) and the second one (the inhomogeneity problem), for non-ellipsoidal shapes. It also yields approximate formulas for the contribution of a non-ellipsoidal inhomogeneity to effective elastic properties.     

多孔材料缓冲吸能特性表征方法

分析了多孔材料缓冲吸能机理，综述了多孔缓冲材料吸能特性的几种表征方法：缓冲曲线、缓冲系数、Janssen因子、Rusch曲线、能量吸收率曲线和能量吸收图，并分析了各种表征方法的优缺点。能量吸收图汇集了应变率和材料结构特征等信息，且能够模型化，对于不同密度多孔材料吸能特性的表征具有一定的普适性。     

Flt3 Signaling in B Lymphocyte Development and Humoral Immunity

The Class III receptor tyrosine kinase Flt3 and its ligand, the Flt3-ligand (FL), play an integral role in regulating the proliferation, differentiation, and survival of multipotent hematopoietic and lymphoid progenitors from which B cell precursors derive in bone marrow (BM). More recently, essential roles for Flt3 signaling in the regulation of peripheral B cell development and affinity maturation have come to light. Experimental findings derived from a multitude of mouse models have reinforced the importance of molecular and cellular regulation of Flt3 and FL in lymphohematopoiesis and adaptive immunity. Here, we provide a comprehensive review of the current state of the knowledge regarding molecular and cellular regulation of Flt3/FL and the roles of Flt3 signaling in hematopoietic stem cell (HSC) activation, lymphoid development, BM B lymphopoiesis, and peripheral B cell development. Cumulatively, the literature has reinforced the importance of Flt3 signaling in B cell development and function. However, it has also identified gaps in the knowledge regarding Flt3-dependent developmental-stage specific gene regulatory circuits essential for steady-state B lymphopoiesis that will be the focus of future studies.     

复合材料网格结构模态分析的均匀化等效建模

复合材料网格结构由于内部结构复杂 , 在有限元分析中难以建立实际模型 , 需要对结构采用均匀化方法进行弹性常数等效。本文中根据结构的最小势能原理和有限元法基本思想 , 对结构的弹性力学基本方程进行了推导 , 使用有限单元法中的位移场 , 根据应变能相等的原则 , 得出了求解等效弹性矩阵的一种比较通用的方法 ;根据动能相等的原则 , 得出了等效质量的求解公式。采用有限元方法 , 对胞元进行了拉伸和剪切载荷下的细观力学分析 , 将分析结果代入到推导的公式 , 求出了复合材料网格结构的等效特性参数 ; 使用求得的等效模型对结构进行了宏观仿真 , 并与实际模型仿真结果进行对比。研究结果表明 , 该等效方法具有较好的精度 , 能够满足工程的需要 , 可用于各类大型结构的分析。      

初始几何缺陷对非强支撑钢框架柱性能的影响

在钢框架二阶弹性分析中,结构整体初始几何缺陷和构件的初始几何缺陷是实际存在的,其影响不应忽略。基于由单根柱和梁组成的框架子结构模型,通过引入以上两种几何缺陷,得出了考虑初始几何缺陷影响的框架柱位移与内力的理论公式。利用该理论模型,可以较准确地分析框架结构整体几何缺陷与构件几何缺陷对二阶弹性弯矩的影响。参数分析结果表明:对于钢框架柱,结构的整体几何缺陷和构件几何缺陷对弯矩的影响均可以等效为作用于楼层处的假想水平力,而假想水平力的大小与作用于该楼层的竖向荷载有关。     

超声电机定子的简化复合梁模型裂纹扩展分析与实验

超声电机工作环境非常复杂,压电陶瓷极易发生断裂失效。为了分析研究电场、预压力及裂纹位置对压电陶瓷断裂失效的影响,将超声电机的定子沿周向简化为弹性复合梁模型,并在压电陶瓷上预制贯穿裂纹。首先用Ansys有限元软件对简化模型进行仿真,分析得到增大电场、预压力能增加裂纹尖端应力值,裂纹更加容易扩展。然后通过实验验证得到增大电场强度裂纹更加容易扩展。