摘要：Traditional fractal pattern design has some disadvantages such as inability to effectively reflect the characteristics of real scenery and texture. We propose a novel pattern design technique combining fractal geometry and image texture synthesis to solve these problems. We have improved Wei and Levoy (2000)’s texture synthesis algorithm by first using two-dimensional autocorrelation function to analyze the structure and distribution of textures, and then determining the size of L neighborhood. Several special fractal sets were adopted and HSL (Hue, Saturation, and Light) color space was chosen. The fractal structure was used to manipulate the texture synthesis in HSL color space where the pattern’s color can be adjusted conveniently. Experiments showed that patterns with different styles and different color characteristics can be more efficiently generated using the new technique.

摘要：A novel micromirror based on the PolyMUMPs process is designed and presented. The hexagonal micromirror with a diameter of 450 μm consists of three supporting bilayer cantilevers and a mirror plate. The bilayer cantilevers, formed with a polysilicon layer and a gold layer, elevate the mirror plate according to residual stress-induced bending. Both analytical and finite element analysis （FEA） models are built to calculate the elevated height of the free end of the cantilever. The analytical solution is in accordance with the FEA simulation results, with longitudinal stresses applied only. Results of a three-dimensional （3D） simulation with two direction stresses applied also show the elevated height to be proportional to the width of the cantilever and the length of the gold layer. Due to the torque of the joint, the elevated heights of the two kinds of cantilevers assembled with the mirror plates are much smaller than those of the free end of the cantilevers. Both micromirrors with different cantilevers are fabricated. The elevated heights of the fabricated micromirrors are measured using Veeco optical profiler, which show good coincidence with simulation results.

摘要：For a hierarchical cognitive radio network(CRN),the secondary users(SUs) may access the licensed spectrum opportunistically,whenever it is not occupied by the primary users(PUs).An important issue for this kind of CRN is the achievable qualityof-service(QoS) performance,such as traffic transmission delay,which is critical to the SUs' traffic *** this paper,we focus on the delay performance analysis of the SU system and the design of the corresponding optimal access strategy for the case of SUs sharing multiple licensed *** our analysis,the transmission of PU and SU traffic is modeled as M/G/1 *** merging the PU and SU traffic,we propose the model of a priority virtual queue on the licensed *** on this model,we obtain the expected system delay expression for SU traffic through M/G/1 preemptive repeat priority queuing *** the case of multiple licensed channel access,the access strategy is further investigated with respect to the expected system delay for SU *** minimizing the expected transmission delay,the optimal access strategy is modeled as a nonlinear programming problem,which can be resolved by means of the classic Genetic Algorithm(GA).Numerical results validate our analysis and design of an optimal access ***,by considering the time taken by the GA approach,we can also adopt the inverse proportional access strategy to obtain near-optimal results in practice.

摘要：We discuss the P-V criticality and phase transition in the extended phase space of Born-Infeld AdS(BIAdS) black hole surrounded by quintessence dark energy, where the cosmological constant Λ is identified with the thermodynamical pressure P. Comparing with Van der Waals(VdW)-like SBH/LBH phase transition of Born-Infeld AdS(BI-AdS) black hole, we find that the BI-AdS black hole surrounded by quintessence dark energy possesses lower critical temperature because of parameter a > 0, even disappears since the parameter a taking enough large values leads to Tc ≤ 0. Moreover, the interesting thermodynamic phenomenon of reentrant phase transition(RPT) are also observed,and the quintessence dark energy plays a similar role in this RPT.

摘要：To improve the computational efficiency of the reliability-based design optimization(RBDO) of flexible mechanism, particle swarm optimization-advanced extremum response surface method(PSO-AERSM) was proposed by integrating particle swarm optimization(PSO) algorithm and advanced extremum response surface method(AERSM). Firstly, the AERSM was developed and its mathematical model was established based on artificial neural network, and the PSO algorithm was investigated. And then the RBDO model of flexible mechanism was presented based on AERSM and PSO. Finally, regarding cross-sectional area as design variable, the reliability optimization of flexible mechanism was implemented subject to reliability degree and uncertainties based on the proposed approach. The optimization results show that the cross-section sizes obviously reduce by 22.96 mm^2 while keeping reliability degree. Through the comparison of methods, it is demonstrated that the AERSM holds high computational efficiency while keeping computational precision for the RBDO of flexible mechanism, and PSO algorithm minimizes the response of the objective function. The efforts of this work provide a useful sight for the reliability optimization of flexible mechanism, and enrich and develop the reliability theory as well.

摘要：As the hot line in NP-hard problems research in recent years, backbone analysis is crucial for phase transition, hardness, and algorithm design. Whereas theoretical analysis of backbone and its applications in algorithm design are still at a begin- ning state yet, this paper took the quadratic assignment problem （QAP） as a case study and proved by theoretical analysis that it is NP-hard to find the backbone, i.e., no algorithm exists to obtain the backbone of a QAP in polynomial time. Results of this paper showed that it is reasonable to acquire approximate backbone by inter- section of local optimal solutions. Furthermore, with the method of constructing biased instances, this paper proposed a new meta-heuristic -- biased instance based approximate backbone （BI-AB）, whose basic idea is as follows： firstly, construct a new biased instance for every QAP instance （the optimal solution of the new instance is also optimal for the original one）; secondly, the approximate backbone is obtained by intersection of multiple local optimal solutions computed by some existing algorithm; finally, search for the optimal solutions in the reduced space by fixing the approximate backbone. Work of the paper enhanced the research area of theoretical analysis of backbone. The meta-heuristic proposed in this paper provided a new way for general algorithm design of NP-hard problems as well.

摘要：Casting blast can greatly reduce the stripping cost and improve the production capacity of opencast coal mines. Key technologies including high bench blasting, inclined hole, millisecond blasting, pre-splitting blasting and casting blast parameters determination which have influence on the effect of casting blast have been researched with the combination of the ballistic theory and experience in mines. The integrated digital processing system of casting blast was developed in order to simplify the design process of casting blast, improve working efficiency and veracity of design result and comprehensively adopt the software programming method and the theory of casting blast. This system has achieved five functions, namely, the 3D visualization graphics management, the intelligent management of geological information, the intelligent design of casting blast, the analysis and prediction of the blasting effect and the automatic output of the design results. Long-term application in opencast coal mines has shown that research results can not only reduce the specific explosive consumption and improve the blasting effect, but also have high value of popularization and application.

摘要：The past decade has seen a growing interest in ocean sensor networks because of their wide applications in marine research,oceanography,ocean monitoring,offshore exploration,and defense or homeland *** sensor networks are generally formed with various ocean sensors,autonomous underwater vehicles,surface stations,and research *** make ocean sensor network applications viable,efficient communication among all devices and components is *** to the unique characteristics of underwater acoustic channels and the complex deployment environment in three dimensional(3D) ocean spaces,new efficient and reliable communication and networking protocols are needed in design of ocean sensor *** this paper,we aim to provide an overview of the most recent advances in network design principles for 3D ocean sensor networks,with focuses on deployment,localization,topology design,and position-based routing in 3D ocean spaces.

摘要：Network coding is proved to have advantages in both wireline and wireless networks. Especially, appropriate network coding schemes are programmed for underlined networks. Considering the feature of strong node mobility in aviation communication networks, a hop-by-hop network coding algorithm based on ad hoc networks was proposed. Compared with COPE-like network coding algorithms, the proposed algorithm does not require overhearing from other nodes, which meets confidentiality requirements of aviation communication networks. Meanwhile, it does save resource consumption and promise less processing delay. To analyze the performance of the network coding algorithm in scalable networks with different traffic models, a typical network was built in a network simulator, through which receiving accuracy rate and receiving delay were both *** simulation results indicate that, by virtue of network coding, the proposed algorithm works well and improves performance significantly. More specifically, it has better performance in enhancing receiving accuracy rate and reducing receiving delay, as compared with any of the traditional networks without coding. It was applied to both symmetric and asymmetric traffic flows and, in particular, it achieves much better performance when the network scale becomes larger. Therefore, this algorithm has great potentials in large-scale multi-hop aviation communication networks.

摘要：Uncertainty model validation has been studied for stable system by several authors. This paper considers uncertainty model validation for unstable systems. Under a similar assumption to study for stable systam, a necessary and suffident condition is obtained for unstable uncertainty models not to be invalidated, which generalizes the results of previous study and show that the uncertainty model validation for unstable systems is again a boundary interpolation problem.