By analogy with internet of things (IoT), internet of vehicles (IoV) which enables ubiquitous information exchange and content sharing among vehicles with little or no human intervention is a key enabler for the intelligent transportation industry. In this paper, we study how to combine both the physical and social layer information for realizing rapid content dissemination in device-to-device vehicle-to-vehicle (D2D-V2V) based IoV networks. In the physical layer, headway distance of vehicles is modeled as a Wiener process, and the connection probability of D2D-V2V links is estimated by employing the Kolmogorov equation. In the social layer, the social relationship tightness that represents content selection similarities is obtained by Bayesian nonparametric learning based on realworld social big data, which are collected from the largest Chinese microblogging service Sina Weibo and the largest Chinese video-sharing site Youku. Then, a price-rising based iterative matching algorithm is proposed to solve the formulated joint peer discovery, power control, and channel selection problem under various quality of service (QoS) requirements. Finally, numerical results demonstrate the effectiveness and superiority of the proposed algorithm from the perspectives of weighted sum rate and matching satisfaction gains.
In the paper, a new method for designing Cosine Modulated Filter Banks (CMFB) is proposed, the prototype filter is designed by optimization method. Firstly, the method appropriately relaxes the limit conditions for perfect reconstruction, the design problem of CMFB is formulated as a nonlinear and unconstrained optimization of an objective function, which stopband cutoff frequency is fixed, passband cutoff frequency is adjusted to minimize the cost function which satisfies reconstruction condition, and directly designs the prototype filter. The simulation results illustrate the proposed method and its improvement over other methods in terms of amplitude distortion, aliasing distortion, signal to noise ratio and reconstruction performance.
A direct-drive motor has the merits of low speed, high torque, and elimination of mechanical deceleration mechanisms, and is widely used in various fields. A novel direct-drive permanent magnet synchronous motor is presented herein, in which all coils are wrapped around the stator yoke in the same orientation. The structure of the novel direct-drive permanent magnet synchronous motor with toroidal windings (N-TWDDPMSM) is introduced and its operating principle is analyzed by describing the variation in the armature magnet field versus time. Furthermore, based on the same power grade and mechanical size, several finite-element models of motors with different windings are established using Magnet software to analyze the distribution of magnetic field, back-electromotive force (back-EMF), power-angle characteristics, loss characteristics, etc. Compared with the traditional permanent magnet synchronous motor (T-PMSM), the traditional permanent magnet synchronous motor with toroidal windings (T-TWPMSM), and the N-TWDDPMSM, the N-TWDDPMSM shows advantages of low speed and high torque, and the feasibility and superiority of the N-TWDDPMSM are verified.
A compact L-band high temperature superconducting (HTS) microstrip input duplexer for satellite communication application has been developed. The duplexer has two output channels with center frequencies at 1200 and 1250 MHz, respectively. It was fabricated on a single piece of 2-in double-sided YBCO thin film on LaAlO 3 substrate with a dimension of 26 × 42 mm. The duplexer consists of a T-junction and two bandpass filters, i.e., a ten-pole filter and an eight-pole filter for the two transmission channels, respectively. Both of the two HTS bandpass filters were specially designed to suppress the second-harmonic spurious passband. Moreover, an HTS bandstop filter is added to the duplexer to improve the out-of-band rejection at a special frequency band. As a result of the preceding special designs, in addition to a very low insertion loss (0.2 dB), considerably sharp band edge (21 dB/MHz), and good voltage standing wave ratio (better than 1.4:1), much deeper out-of-band rejection (more than 75 dB) can be realized in a much wider frequency range, i.e., up to 3 GHz, which is almost three times above the center frequency of the passbands. Although all the elements of the duplexer are integrated within a single-piece YBCO film and the layout is compact, excellent isolation (higher than 80 dB) between the two channels has still been achieved.Index Terms-Bandpass filter, bandstop filter, high temperature superconducting (HTS) duplexer. His current research interests are HTS microwave devices and microwave tunable filters.
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