Efficient multi‐hop wireless broadcast protocol in vehicular networks using automated threshold function design

Vehicular networking applications often use multi‐hop wireless broadcasting as a primary data dissemination mechanism. Therefore, protocols that efficiently and thoroughly propagate application data while adapting to a wide range of network density, vehicle distribution pattern, channel quality, and other conditions are critical for vehicular communications. Here, we design the Statistical Vehicular Broadcast (SVB) protocol to efficiently distribute data via multi‐hop broadcast in vehicular networks. First, we present an automated optimization technique for the design of threshold functions in statistical broadcasting methods. Next, we compare and analyze known statistical techniques, including different fundamental methods, assessment delay algorithms, and failsafe mechanisms. All combinations of these techniques are given threshold functions optimized using the proposed automated procedure then are evaluated in a wide range of simulations. High‐level statistical design principles and recommendations are established based on analysis of these results. Finally, we apply those principles to design SVB. It is evaluated in JiST/SWANS and is shown to achieve a high target reachability level while consuming less bandwidth than similar protocols across urban and highway vehicular networking scenarios.Copyright © 2014 John Wiley & Sons, Ltd.     

Minimal within-host dengue models highlight the specific roles of the immune response in primary and secondary dengue infections

In recent years, the within-host viral dynamics of dengue infections have been increasingly characterized, and the relationship between aspects of these dynamics and the manifestation of severe disease has been increasingly probed. Despite this progress, there are few mathematical models of within-host dengue dynamics, and the ones that exist focus primarily on the general role of immune cells in the clearance of infected cells, while neglecting other components of the immune response in limiting viraemia. Here, by considering a suite of mathematical within-host dengue models of increasing complexity, we aim to isolate the critical components of the innate and the adaptive immune response that suffice in the reproduction of several well-characterized features of primary and secondary dengue infections. By building up from a simple target cell limited model, we show that only the innate immune response is needed to recover the characteristic features of a primary symptomatic dengue infection, while a higher rate of viral infectivity (indicative of antibody-dependent enhancement) and infected cell clearance by T cells are further needed to recover the characteristic features of a secondary dengue infection. We show that these minimal models can reproduce the increased risk of disease associated with secondary heterologous infections that arises as a result of a cytokine storm, and, further, that they are consistent with virological indicators that predict the onset of severe disease, such as the magnitude of peak viraemia, time to peak viral load, and viral clearance rate. Finally, we show that the effectiveness of these virological indicators to predict the onset of severe disease depends on the contribution of T cells in fuelling the cytokine storm.     

北京西山地质旅游资源开发

北京市西山地区山、水、洞并举,峰、谷、泉、瀑兼备,是发展地质旅游的理想之地。但西山门头沟处的风暴岩等特色地质景观在国内鲜为人知,却受到了许多国外地质专家的重视。本文针对西山寒武系海相碳酸盐岩地层特色地质景观,从景点的区域位置、景点描述和成因机理3个方面对风暴岩、核形石带、藻丘、豹皮灰岩特色景点做了详细介绍,并提出景点开发建议。开辟北京西山寒武系海相碳酸盐岩地层地质旅游观赏路线不仅可以保护国家地质资源,也可以提高游客的地质兴趣与素养。     

基于Hybrid Port的VLAN实现

VLAN具有控制网络广播风暴、保障网络安全和简化网络管理等特点，因此在局域网中得到广泛的应用。在某些场合下必须允许特定VLAN之间相互访问，通常实现方式是划分IP子网并通过IP进行路由。但是在某些特定的场合中，由于IP紧缺以及保障IP真实等原因，不能采取这样的方案。为此本文提出了一种基于混杂端口（hybrid port）的虚拟局域网（VLAN）实现方案。通过这种方式设计，在提高网络安全性的同时，避免了IP地址紧缺的问题。最后给出了基于混杂端口VLAN设计方案。     

永定新河淤积现状及冲淤演变分析

依据永定新河河道多年的冲淤形态和潮汐水流、泥沙的特征，对永定新河的冲淤规律进行了分析，提出了海河流域淤泥质河口在以潮流为主要动力条件下，感潮河道的冲淤规律，揭示了淤泥质河口在潮流动力作用下的演变过程，对类似河道及河口治理具有借鉴作用。     

黄河中游粗泥沙集中来源区产沙规律综述

在前人研究的基础上分析总结了该区特有的暴雨洪水产沙规律：暴雨是侵蚀产沙的主要动力，暴雨、洪水、泥沙之间存在着必然的关系；洪水发生时间集中，峰高量大，暴涨暴落，对黄河中游大洪峰的形成具有决定性影响；侵蚀产沙强烈而粗泥沙集中，输沙能力强，洪水含沙量高，是黄河粗泥沙的集中来源地；河龙区间特别是粗泥沙集中来源区频繁或连续的暴雨洪水对黄河输沙有重要影响；随着治理水平的提高，区域洪水有减小趋势，但泥沙量变化不明显，大部分支流的洪峰流量、洪水含水量反应不敏感，说明一般规模和水平的治理工程还不能有效控制区域大洪水特别是特大洪水的泥沙。     

广西北部地区"85·5"特大暴雨洪水分析

198 5年 5月 2 4～ 2 7日 ,桂北地区兴安、全州、灌阳三县境内骤降一场历史罕见的暴雨 (简称“85·5”暴雨 ) ,暴雨中心雨量达 5 6 0mm ,10 0mm的降雨量笼罩面积达 5 0 0 0km2 ,导致湘江上游干支流洪水遭遇严重 ,是有历史资料以来的最大洪水。研究分析本次暴雨洪水过程 ,对湘江上游流域综合治理、规划设计、洪水预报、防汛抗洪等都具有极为重要的意义。     

黄河三门峡一花园口“82．8”大暴雨期间水汽输送分析

通过计算１９８２年７月２９日～８月２日黄河中游三门峡一花园口间区域的水汽通量、水汽通量散度和水汽净输送等特征量，分析了这次暴雨过程的水汽源地、水汽输送的物理过程和水汽净输送量与暴雨洪水的关系。结果表明，这次暴雨的水汽主要来自东部洋面上，低空偏东风急流和三花间地区的辐合上升运动共同构成了该地区水汽输送的通道，暴雨区内水汽的缔向福合是形成暴雨水汽福合的主要过程，水汽的经向辐散则是水汽输出的主要原因，而水汽的低层辐合、高层辐散及低层水汽向高层的垂直输送是降雨增强的机制。     

桥子沟流域“1987.4.19”暴雨洪水及土壤侵蚀调查分析

桥子沟流域属黄土丘陵沟壑区第三副区。１９８７年４月１９日，该流域突降暴雨，造成了严重的水土流失。此次暴雨降雨集中、历时知、强度大，所形成的洪水历时短、峰值大。土壤侵蚀调查分析结果表明，本次暴雨造成该流域坡面总侵蚀量２０１９０ｔ，平均侵蚀模数为８７３８ｔ／ｋｍ＾２，造成该流域沟道总侵蚀量７０８７ｔ，侵蚀模数为５０８６０ｔ／ｋｍ＾２；坡面和沟道侵蚀量所占比例分别为７４％和２６％。     

A new psychophysical method: Method of transposition or equal-appearing relations.

"In many experiments dealing with perceptual phenomena, investigators try to find a stimulus which appears equal to a standard stimulus. It often happens, however, that the procedure involved in finding the equivalent stimulus alters the stimulus pattern so that the measurement is not made on the original stimulus pattern. To avoid this difficulty, a new psychophysical method, which is named the method of transposition or the method of equal-appearing relations, was proposed. The major advantage of this method over the traditional ones is that it leaves the original stimulus pattern intact." (PsycINFO Database Record (c) 2010 APA, all rights reserved)