Papers by Keyword: Bandwidth (BW)

Abstract: The performance of bandwidth and transmitting voltage response to the piezoelectric dual-excited underwater acoustic transducer are studied by FEM software ANSYS in the paper. At first, the mechanism of the dual-excited transducer is analyzed, once this is done, The FEM models with different axial dimension of the piezoelectric stack and the mid mass, Al and steel are specified for the material of mid mass respectively. the calculated curves are contrasted, the results were found that the appropriate proportion of the mid-mass to the stack will broaden the bandwidth and enhance the transmitting voltage response, the increase of the thickness of the mid-mass will reduce the transmitting voltage response, and the bandwidth can be expanded to 13kHz, the resonance frequency has shifted to a higher value, it ranges from 34kHz to 46kHz. The results show that one octave bandwidth could be achieved and provide support for the next production and experiment of the broadband underwater acoustic transducer.

Abstract: The resonance frequency of the cymbal transducer ranges from 2kHz to 40kHz and its effective electromechanical coupling factor is around 20%. Finite element analysis has been performed to ascertain how the transducer’s makeup affect the transducer’s performance parameters. Two-dimensional axisymmetric model of the cymbal transducer was founded by finite element software-ANSYS, the application of the element type was discussed and the FEM models were built up under the far field condition. Eight groups of cymbal transducers of resonance frequency around 3kHz with different structural dimensions were designed. It was better for choosing the cymbal transducer of the 8mm cavity coping diameter, 20.8mm cavity bottom diameter and 26.8mm piezoelectric ceramic wafer diameter than others for reducing distortion degree of the signal and improving communication turnover in the researched cymbal transducers. It was appropriate for choosing the cymbal transducer of the 8mm cavity coping diameter, 22.4mm cavity bottom diameter and 26.4mm piezoelectric ceramic wafer diameter in order to improve the free-field voltage sensitivity and transmission efficient.

Abstract: The three common frequency selective surface (FSS) structure, i.e. ring, crosses and Y-aperture which have the same center frequencies are designed, then the three FSS structures are placed at absorbing materials to form complex absorbing structures which are simulated by means of spectral domain approach. Therefore, the effects of different FSS on the characteristics of absorbing materials are studied and the influence laws are given. This research offers reference to element selection for the application of common FSS to absorbing materials.

Abstract: The stabilization, tracking and pointing systems are essential features of modern fire control and surveillance systems. The criteria for precision stabilization may vary from a few hundred micro-radians to few nano-radians for achieving jitter free image depending upon the application scenario. The Line of sight (LOS) is stabilized by mounting the optical payload on a gimbal platform and designing the control system around them. The paper describes a choquet fuzzy integral based control algorithm developed for LOS controlling and stabilizing application. In this approach, q-measure is estimated to simplify the computation of λ-measure that aggregates the information from the weighted inputs. The output of fuzzy rules, which are formulated by defining the product of weighted inputs are required to compute the fuzzy measure in the form of Choquet fuzzy integral.

Abstract: Simulation systems with hardware-in-loop are composed by three-Axis virtual flight motion simulator, simulation computer, load torque simulator, and visual simulation systems. Three-Axis Virtual Flight Motion Simulator are used to simulate the attitude of missile in simulation system with hardware-in-loop, so its performance influenced the result of simulation directly. This paper mainly analyzed the factors which influenced the performance of a three-Axis virtual flight motion simulator which we are used now in the lab, then analyzed the entire simulation system’s error caused by these factors through numerical simulation method. By analysis we can see that bandwidth is the main factor influenced the precision of simulation systems with hardware-in-loop, mechanical device installation error and measurement error may also cause some errors of the systems at the same time.

Abstract: Energy bills are on the rise and with the recent attention to saving the global environment. Saving energy (minimizing energy consumption) is becoming a standard issue for all industrial and commercial applications. Moreover, provisioning of quality of service (QoS) for multimedia traffic in wireless networks is complicated due to user mobility and limited wireless resources. Bandwidth (throughput) and hop count and are the important parameters in QoS requirements. In this article, a novel QoS constrained minimum power cellular ad hoc augmented network (QCMP CAHAN) architecture is proposed for next generation wireless networks. The QCMP CAHAN architecture is proposed to find the optimal minimum power route under bandwidth and hop-count constraints (QoS constraints). The QCMP CAHAN has a hybrid architecture, in which each mobile terminal (MT) of CDMA cellular networks has ad hoc communication capability. The QCMP CAHAN is an evolutionary approach to traditional cellular networks. We show that the total energy consumed by the MTs is lower in the case of QCMP CAHAN than in the case of traditional cellular networks. As the ad hoc communication range of each MT increases, the total transmitted energy in QCMP CAHAN decreases. However, due to the increased number of hops involved in information delivery between source and destination, the end-to-end delay increases. The maximum end-to-end hop count will be limited to a specified tolerable value, and QCMP CAHAN has ability to adapt to various hop-count constraints for different services. A MT in QCMP CAHAN will not relay any message when its ad hoc communication range is zero, and if this is the case for all MTs, then QCMP CAHAN reduces to the traditional cellular networks. Moreover, the bandwidth constrained problem in QCMP CAHAN is described as a nonlinear programming problem to minimize the total power consumption. We solved the bandwidth constrained problem in QCMP CAHAN by allocating optimum traffic rates on different routes between source and destination.

Abstract: This paper proposed an effective approach for extending the bandwidth of MEMS vibratory gyroscope by employing the electrostatic force feedback control. The mathematical model for the bandwidth is established through the dynamic model of the gyroscope, which indicates that the bandwidth of the sensor depends on the difference between the resonant frequencies of the two working modes. The system bandwidth can be enlarged by utilizing electrostatic force rebalance control to null Coriolis force caused by external angular rate which can also improve the performance of the transient response. Simulation results forecast a satisfactory performance of the control system with suggested control method.

Abstract: Aiming to the shortcoming of traditional route protocols in cognitive radio networks, cognitive radio routing and optimal spectrum assignment (CRRSA) algorithm was proposed. In this paper, we consider the situation that non-interfering among the adjacent jump, and present the optimal allocation of available spectrum, and then calculate the bandwidth of end-to-end path, finally select the maximize bandwidth of end-to-end path as the best transmission route. Simulation results show that the End-to-End bandwidth of CRRSA is larger than that of traditional routing algorithm.

Abstract: Ad Hoc network is a novel type of mobile computer network, Its own distinctive quality entrusts with its huge prospects for development. This paper presents a TM program, and thus to determine the proportion of each data stream in multi-hop ad hoc wireless networks accounts for the channel time. At the same time, TM program based on a proposed multi-hop wireless data flow algorithm for fair bandwidth allocation.

Abstract: SpaceWire is used for on-board satellite networks. It is proposed by the ESA as the basis for future data-handing architectures. It takes an indispensable role for the shortage of bandwidth of bus among data processing. Based on the research of SpaceWire Network, some parameters, such as delay, bit error ratio, bandwidth and throughput, a new scheme of the testing about the parameters of SpaceWire was proposed. Then its implementation technology was analyzed and explained.