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摘要:A trajectory generator based on vehicle kinematics model was presented and an integrated navigation simulation system was *** that the tight relation between vehicle motion and topography,a new trajectory generator for vehicle was proposed for more actual ***,a vehicle kinematics model was built based on conversion of attitude vector in different coordinate ***,the principle of common trajectory generators was ***,combining the vehicle kinematics model with the principle of dead reckoning,a new vehicle trajectory generator was presented,which can provide process parameters of carrier anytime and achieve simulation of typical actions of running ***,IMU(inertial measurement unit) elements were simulated,including accelerometer and *** setting up the simulation conditions,the integrated navigation simulation system was verified by final performance *** result proves the validity and flexibility of this design.
摘要:Transformation thermodynamics as a major extension of transformation optics has recently received considerable attention. In this paper, we present two-dimeusional (2D) and three-dimensional (3D) diamond-shaped transient thermal cloaks with non-singular homogeneous material parameters. The absence of singularity in the parameters results from the fact that the linear coordinate transformation is performed by expanding a line segment rather than a point into a region, while the mechanism behind the homogeneity is the homogeneous stretching and compression along orthogonal directions during the transformation. Although the derived parameters remain anisotropic, we further show that this can be circumvented by considering a layered structure composed of only four types of isotropic materials based on the effective medium theory. Numerical simulation results confirm the good performance of the proposed cloaks.
摘要:This paper aims at designing a better net-work i,,imozatopm strategy to fight against the Sus- ceptible-Infected-Susceptible (SIS) type epidemic spreading in networks. Previous work used the nurrber of drops in the spectral radius of the net-work for evaluation and guiding the design of im-munization strategies. Instead, we propose using the infected node number in the steady state of SIS spreading as the appropriate metric. We use the metric to point out the limitations of the Equal Graph Partitioning (EGP) strategy and the "max-△λ" strategy, which are two representative network inmmnization strategies, and then identify the criti-cal role of epidemic spreading parameters in the e-valuation and design of network immuzization strat- egies. Based on all of these, we design a new immuzization strategy. Simulation results show that our strategy performs consistently better than the EGP strategy. In many cases, it uses only 50% less re-sources to achieve the same immuzization effect.
摘要:The multi-component composition characteristics of high-temperature near-α Ti alloys were investigated in the present work by means of a cluster formula approach. The uniform cluster formula [CN12 cluster](glue atom)3 for the hexagonal close-packed α solid solution was first obtained based on the Friedel oscillation theory, with a total atom number in the formula of Z = 16. Then it was analyzed that the Z values in the cluster composition formulas of typical near-α Ti alloys are within the range of Z = 16.0016.30, being perfectly consistent with the ideal Z = 16. Based on it, a series of new alloys with Z = 16 and with Nb/Ta substitution for Mo in Ti1100 alloy were designed, suction-cast into φ 6 mm rods, and then heat-treated with solid solution and aging. It was found that the alloy with co-addition of Mo, Ta and Nb has a high strength and good ductility at both room and high temperatures. More importantly, the additions of Nb and Ta can contribute to the formation of continuous and compact Al2O3 scales, resulting in an obvious improvement of oxidation resistances at both 923 K and 1073 K. The effects of Mo, Ta and Nb on the oxidation behaviors of the designed alloys at 1073 K were further discussed.
摘要:这份报纸调查控制港口的 Hamiltonian (PCH ) 多代理人系统的产量一致问题与修理并且切换的拓扑学。第一,一个分布式的组产量一致协议经由塑造方法全球性到达稳定性和组产量一致的能量被设计。第二,一个新分布式的控制协议被使用 PCH 系统的结构的性质建议。这个协议的优点是它能由构造一种虚拟邻居转变指导的图到未受指导的图。第三,一个控制协议被设计,扩大 LaSalle0s 不变性原则在联合连接的拓扑学条件下面为交换系统发展了让所有代理人当拓扑学正在切换时,到达输出一致。最后,有模拟的一些解说性的例子被提供表明在这份报纸设计的协议的有效性。
摘要:In this paper, a composite control scheme for macro-micro dual-drive positioning stage with high accel- eration and high precision is proposed. The objective of control is to improve the precision by reducing the influence of system vibration and external noise. The positioning stage is composed of voice coil motor (VCM) as macro driver and piezoelectric actuator (PEA) as micro driver. The precision of the macro drive positioning stage is improved by the com- bined PID control with adaptive Kalman filter (AKF). AKF is used to compensate VCM vibration (as the virtual noise) and the external noise. The control scheme of the micro drive positioning stage is presented as the integrated one with PID and intelligent adaptive inverse control approach to compensate the positioning error caused by macro drive positioning stage. A dynamic recurrent neural networks (DRNN) based inverse control approach is proposed to offset the hysteresis nonlinearity of PEA. Simulations show the positioning precision of macro-micro dual-drive stage is clearly improved via the proposed control scheme.
摘要:This article investigates transmitter design in Rayleigh fading multiple input multiple output (MIMO) channels with spatial correlation when there are channel uncertainties caused by a combined effect of channel estimation error and limited feedback. To overcome the high computational complexity of the optimal transmit power allocation, a simple and suboptimal allocation is proposed by exploiting the transmission constraint and differentiating a bound based on Jensen inequality on the channel capacity. The simulation results show that the mutual information corresponding to the proposed power allocation closely approaches the channel capacity corresponding to the optimal one and meanwhile the computational complexity is greatly reduced.
摘要:Double-weight optical code division multiple access(OCDMA) systems are proposed for studying differentiated quality-of-service transmission. Based on quadratic congruence code(QCC), we construct a one-dimensional double-weight code family, which can be well utilized in incoherent synchronous double-weight OCDMA networks. By introducing algebraic transformation to code sequences of QCC in level 1, we obtain multiple double-weight codes with cross-correlation 1. Under the same-bit-power assumption, the performance of low-weight codes can be significantly improved and is always superior to that of high-weight codes in double-weight OCDMA systems with power control. This property is contrary to previous conclusions under the same-chip-power assumption.
摘要:Aspect-oriented modeling can uncover potential design faults, yet most existing work fails to achieve both separation and composition in a natural and succinct way. This study presents an aspect-oriented modeling and analysis approach with hierarchical Coloured Petri Nets(HCPN). HCPN has sub-models and well-defined semantics combining a set of submodels. These two characteristics of HCPN are nicely integrated into aspect oriented modeling. Submodels are used to model aspects while the combination mechanism contributes to aspects weaving. Furthermore, the woven aspect oriented HCPN model can be simulated and analyzed by the CPN Tools. A systematic web application case study is conducted. The results show the system original properties are satisfied after weaving aspects and all design flaws are revealed. As such, the approach can support web application design and analysis in an aspect-oriented fashion concisely and effectively.
摘要:Lightweight and efficient carbon-based microwave absorbents are significant in addressing the increasing severity of electromagnetic *** this study,hierarchical NiO/Ni nanosheets with a tuneable phase and morphology supported on a carbon fiber substrate(CF@NiO/Ni)were fabricated using a hydrothermal approach and post-annealing *** the annealing temperature increases,more metallic Ni is formed,and an apparent porosity appears on the sheet *** from the advantages of a three-dimensional(3D)conducting network,hierarchical porous structure,reinforced dipole/interface polarization,multiple scattering,and good impedance matching,the CF@NiO/Ni-500 composite exhibits an excellent microwave absorption performance even at a filling rate of only 3wt%.Specifically,its minimal reflection loss is-43.92 dB,and the qualified bandwidth is up to 5.64 *** addition,the low radar cross-section area of the CF@NiO/Ni composite coating confirms its strong ability to suppress electromagnetic wave *** expect that this work could contribute to a deeper understanding of the phase and morphology evolution in enhancing microwave absorption.
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