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211.
Collaborative spectrum sensing is proposed to improve the detection performance in cognitive radio (CR) networks. However,
most of the current collaborative sensing schemes are vulnerable to the interference of the malicious secondary users (SUs).
In this paper we propose a reputation-based collaborative spectrum sensing scheme to improve the security of cooperative sensing
by mitigating the impacts of misbehaviors. The fusion center calculates the reputation rating of each SU according to their
history reports to weight their sensing results in the proposed scheme. We analyze and evaluate the performance of the proposed
scheme and its advantages over previous schemes in expansibility and integrity. Simulation results show that the proposed
scheme can minimize the harmful influence from malicious SUs. 相似文献
212.
Based on the analysis of heat transfer mechanics, physical and chemical change of pellet drying and preheating process in
grate, the mathematical model is established and solved by three-diagonal matrix algorithm. With Visual Basic 6.0 a simulation
software is developed. The model is verified by measurements at a domestic pellet plant, and the temperature distribution
of pellet bed is gained. Meanwhile, the influence of different operation parameters on the pellet thermal process is studied.
The results can be taken as a basis of practical production control and the grate optimizing design. 相似文献
213.
TANGLi-qiang ZHENGGui CAIYan-hong 《船舶与海洋工程学报》2004,3(2):73-78
A mechanical model of visco-elastic material is established in order to investigate viscous effect in dynamic growing crack-tip field of mode Ⅱ. It is shown that in stable creep growing phase, elastic deformation and viscous deformation are equally dominant in the near-tip field, the stress and strain have the same singularity, namely, (σε) ∝r^-1/(n-1). The asymptotic solutions of separatied variables of stress, stain and displacement in crack-tip field are obtained by asymptotic analysis, and the results of numerical value of stress and strain in crack-tip field are obtained by shooting method. Through numerical calculation, it is shown that the near-tip fields are mainly governed by the creep exponent n and Mach number M. By the asymptotic analysis to the crack-tip field, the fracture criterion of mode Ⅱ dynamic growing crack of visco-elastic materials is put forward from the point of view of strain. 相似文献
214.
Distributed information systems require complex access control which depends upon attributes of protected data and access
policies. Traditionally, to enforce the access control, a file server is used to store all data and act as a reference to
check the user. Apparently, the drawback of this system is that the security is based on the file server and the data are
stored in plaintext. Attribute-based encryption (ABE) is introduced first by Sahai and Waters and can enable an access control
mechanism over encrypted data by specifying the users’ attributes. According to this mechanism, even though the file server
is compromised, we can still keep the security of the data. Besides the access control, user may be deprived of the ability
in some situation, for example paying TV. More previous ABE constructions are proven secure in the selective model of security
that attacker must announce the target he intends to attack before seeing the public parameters. And few of previous ABE constructions
realize revocation of the users’ key. This paper presents an ABE scheme that supports revocation and has full security in
adaptive model. We adapt the dual system encryption technique recently introduced by Waters to ABE to realize full security. 相似文献
215.
Aiming at the problem that the fast tracking algorithm using spatio-temporal context (STC) will inevitably lead to drift and even lose the target in long-term tracking, a new algorithm based on spatio-temporal context that integrates long-term tracking with detecting is proposed in this paper. We track the target by the fast tracking algorithm, and the cascaded search strategy is introduced to the detecting part to relocate the target if the fast tracking fails. To a large extent, the proposed algorithm effectively improves the accuracy and stability of long-term tracking. Extensive experimental results on benchmark datasets show that the proposed algorithm can accurately track and relocate the target though the target is partially or completely occluded or reappears after being out of the scene. 相似文献
216.
This paper proposes a non-linear dynamics model for articulated vehicles. This model is able to capture common low-speed behaviours of any articulated vehicles off-highway, such as operating for a corner or roundabout on a cambered or slippery surface. It can be used to assess the low-speed manoeuvrability of articulated vehicles under such manoeuvres and conditions. The vehicle model was validated by comparing its path tracking performance to that of the field tests. 相似文献
217.
Circuit net list bipartitioning using simulated annealing technique has been proposed in the paper. The method converges asymptotically
and probabilistically to global optimization. The circuit net list is partitioned into two partitions such that the number
of interconnections between the partitions is minimized. The proposed method begins with an innovative clustering technique
to obtain a good initial solution. Results obtained show the versatility of the proposed method in solving non polynomial
hard problems of circuit net list partitioning and show an improvement over those available in literature. 相似文献
218.
In a coil box between the roughing and finishing stands on a hot strip mill, a problem has been encountered that the entry
region of the plate touches the bending rolls and deforms. As a result, the defective coil occurs. The condition of plate
bending, which forms a new deformation feature in coiling, is analyzed. In this paper, the authors focus on the research of
the effects of coiling parameters, such as the thickness of plate, roll speed and feeding speed of plate in coil box, and
on specific plate bending. A finite element method is developed to simulate this coiling process. Based on numerical simulation,
the effects of the coiling parameters on the mechanics and deformation of the bending plate are obtained. Numerical simulation
tests have verified the validity of the developed model. 相似文献
219.
A radio frequency identification (RFID) yoking proof scheme can generate proofs of simultaneous presence of two tags in the
range of a specified reader so that an off-line verifier can verify the proofs later. This proof has found several interesting
applications. However, many existing RFID yoking schemes are vulnerable to replay attacks. To overcome the weaknesses, Cho
et al. proposed a new RFID yoking proof protocol and a new grouping protocol. Unfortunately, Cho et al.’s schemes are still
vulnerable to replay attacks. In this paper, in addition to demonstrating weaknesses, we further discuss the rationale behind
these weaknesses to provide a guide line for designing secure RFID yoking schemes. Based on the guide line, we propose a new
RFID yoking scheme and a new RFID grouping scheme. Performance evaluation shows that our scheme outperforms its counterparts. 相似文献
220.