Achieving fair service with a hybrid scheduling scheme for CICQ switches

Providing performance guarantees for arriving traffic flows has become an important measure for today’s routing and switching systems. However, none of current scheduling algorithms built on CICQ (combined input and cross-point buffered) switches can provide flow level performance guarantees. Aiming at meeting this requirement, the feasibility of implementing flow level scheduling is discussed thoroughly. Then, based on the discussion, it comes up with a hybrid and stratified fair scheduling (HSFS) scheme, which is hierarchical and hybrid, for CICQ switches. With HSFS, each input port and output port can schedule variable length packets independently with a complexity of O(1). Theoretical analysis show that HSFS can provide delay bound, service rate and fair performance guarantees without speedup. Finally, we implement HSFS in SPES (switch performance evaluation system) to verify the analytical results.     

A secure routing model based on distance vector routing algorithm

Distance vector routing protocols have been widely adopted as an efcient routing mechanism in current Internet,and many wireless networks.However,as is well-known,the existing distance vector routing protocols are insecure as it lacks of efective authorization mechanisms and routing updates aggregated from other routers.As a result,the network routing-based attacks become a critical issue which could lead to a more deteriorate performance than other general network attacks.To efciently address this issue,this paper,through analyzing the routing model and its security aspect,and presents a novel approach on guaranteeing the routing security.Based on the model,we present the security mechanism including the message exchange and update message security authentication mechanism.The suggested approach shows that the security mechanism can efectively verify the integrity and validate the freshness of routing update messages received from neighbor nodes.In comparison with exiting mechanisms(SDV,S-RIP etc),the proposed model provides enhanced security without introducing significant network overheads and complexity.     

An indoor localization system in a multiblock workspace

As service robots and other ubiquitous technology have evolved, an increasing need for the autonomous navigation of mobile objects has arisen. In a large number of localization schemes, the absolute-position estimation method, which relies on navigation beacons or landmarks, has been widely used as it has the advantages of being economical and accurate. However, only a few of these schemes have expanded their application to complicated workspaces, or those that have many rooms or blocks. As the navigation of mobile objects in complicated workspaces is vital for ubiquitous technology, multiblock navigation is necessary. This article presents methodologies and techniques for the multiblock navigation of the indoor localization system with active beacon sensors. This new indoor localization system design includes ultrasonic attenuation compensation, dilution-of-precision analysis, and a fault detection and isolation algorithm using redundant measurements. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Theory and techniques of data mining in CGF behavior modeling

For the large quantity of data,rules and models generated in the course of computer generated forces (CGFs) behavior modeling,the common analytical methods are statistical methods based on the tactical rules,tactical doctrine and empirical knowledge.However,from the viewpoint of data mining,we can find many of these analytical methods are also each-and-every different data mining methods.In this paper,we survey the data mining theory and techniques that have appeared in the course of CGF behavior modeling f...     

Effect of nanopore size on poly(dT)30 translocation through silicon nitride membrane

The nanopore size effect on translocation of poly(dT)30through Si3N4 membrane is investigated.In this paper,we report that the speed of the poly(dT)30 transport through Si3N4 nanopores can be slowed down by half through increasing the nanopore diameter from 4.8 nm to 10.8 nm.The results are consistent with our simulation results.Besides,the current blockage induced by DNA passing through the nanopore is less obvious as pore diameter is larger,which is in good agreement with the theoretical prediction.The conclusion about DNA transport through nanopores is beneficial for the design of DNA sequencing devices.     

上海市长江隧道工程洞门中心坐标精确测定

根据上海市长江隧道工程贯通处洞门中心坐标测量的卖际情况，利用数学方法将空间三维的洞门钢环实测坐标拟合出三维方程，精确求取钢环中心的三维坐标。     

面向IPv4／v6的BGP平滑重启的设计与实现

BGP通过平滑重启机制,可以最小化BGP重启所引起的对路由的负面影响,保证BGP在重启阶段仍然可以提供转发数据服务。文中着重于面向IPv4/v6的平滑重启能力的具体实现,介绍了平滑重启的工作过程和设计实现方法,并阐述了关键技术难点。目前,BGP的平滑重启功能已经在基于Linux的T比特路由器中实现。     

烟囱筒壁多层结构相互作用的短时超高温非稳态温度场计算

针对实际烟囱的筒壁为多层结构组成，并针对低温烟囱存在短时超高温的现象，运用拉普拉斯变换法，给出了烟囱筒壁的一维非稳态物理模型及数学模型，得到了考虑烟囱筒壁多层结构相互作用下的瞬态温度计算公式。并结合算例给出了在短时超高温条件下烟囱筒身沿径向的瞬态温度分布。     

Molecular dynamics simulation of the test of single-walled carbon nanotubes under tensile loading

Molecular dynamics (MD) simulations were performed to do the test of sin-gle-walled carbon nanotubes (SWCNT) under tensile loading with the use of Bren-ner potential to describe the interactions of atoms in SWCNTs. The Young’s modulus and tensile strength for SWCNTs were calculated and the values found are 4.2 TPa and 1.40―1.77 TPa, respectively. During the simulation, it was found that if the SWCNTs are unloaded prior to the maximum stress, the stress-strain curve for unloading process overlaps with the loading one, showing that the SWCNT’s de-formation up to its fracture point is completely elastic. The MD simulation also demonstrates the fracture process for several types of SWCNT and the breaking mechanisms for SWCNTs were analyzed based on the energy and structure be-havior.     

Synchronous estimation of DTM and fractional vegetation cover in forested area from airborne LIDAR height and intensity data

We proposed a method to separate ground points and vegetation points from discrete return, small footprint airborne laser scanner data, called skewness change algorithm. The method, which makes use of intensity of laser scanner data, is especially applicable in steep, and forested areas. It does not take slope of forested area into account, while other algorithms consider the change of slope in steep forested area. The ground points and vegetation points can be used to estimate digital terrain model (DTM) and fractional vegetation cover, respectively. A few vegetation points which were classified into the ground points were removed as noise before the generation of DTM. This method was tested in a test area of 10000 square meters. A LiteMapper-5600 laser system was used and a flight was carried out over a ground of 700–800 m. In this tested area, a total number of 1546 field measurement ground points were measured with a total station TOPCON GTS-602 and TOPCON GTS-7002 for validation of DTM and the mean error value is −18.5 cm and the RMSE (root mean square error) is ±20.9 cm. A data trap sizes of 4 m in diameter from airborne laser scanner data was selected to compute vegetation fraction cover. Validation of fractional vegetation cover was carried out using 15 hemispherical photographs, which are georeferenced to centimeter accuracy by differential GPS. The gap fraction was computed over a range of zenith angles 10° using the gap light analyzer (GLA) from each hemispherical photograph. The R ² for the regression of fractional vegetation cover from these ALS data and the respective field measurements is 0.7554. So this study presents a method for synchronous estimation of DTM and fractional vegetation cover in forested area from airborne LIDAR height and intensity data.