On Differentiation Among Pilot Signals of Multiple Mobile Targets in Retro-Reflective Beamforming for Wireless Power Transmission

An experimental study is conducted on several retro-reflective beamforming schemes for wireless power transmission to multiple wireless power receivers(referred to herein as“targets”).The experimental results demonstrate that,when multiple targets broadcast continuous-wave pilot signals at respective frequencies,a retro-reflective wireless power transmitter is capable of generating multiple wireless power beams aiming at the respective targets as long as the multiple pilot signals are explicitly separated from one another by the wireless power transmitter.However,various practical complications are identified when the pilot signals of multiple targets are not appropriately differentiated from each other by the wireless power transmitter.Specifically,when multiple pilot signals are considered to be carried by the same frequency,the wireless power transmission performance becomes heavily dependent on the interaction among the pilot signals,which is highly undesirable in practice.In conclusion,it is essential for a retro-reflective wireless power transmitter to explicitly discriminate multiple targets’pilot signals among each other.

Optimal Design of Aperture Illuminations for Microwave Power Transmission with Annular Collection Areas

This work presents an optimal design method of antenna aperture illumination for microwave power transmission with an annular collection area.The objective is to maximize the ratio of the power radiated on the annular collection area to the total transmitted power.By formulating the aperture amplitude distribution through a summation of a special set of series,the optimal design problem can be reduced to finding the maximum ratio of two real quadratic forms.Based on the theory of matrices,the solution to the formulated optimization problem is to determine the largest characteristic value and its associated characteristic vector.To meet security requirements,the peak radiation levels outside the receiving area are considered to be extra constraints.A hybrid grey wolf optimizer and Nelder–Mead simplex method is developed to deal with this constrained optimization problem.In order to demonstrate the effectiveness of the proposed method,numerical experiments on continuous apertures are conducted;then,discrete arrays of isotropic elements are employed to validate the correctness of the optimized results.Finally,patch arrays are adopted to further verify the validity of the proposed method.

Manufacturing Development Emphases on Power Generation and Transmission Apparatus in 11th Five-Year Plan Period and Prospect to the Year 2020

Based on predictions on Chinese power development in the coming 20 years, this paper introduces the emphases and key technologies in power sources and power network construction, and puts for ward the major tasks and technological orientation for machinery manufacturers to supply qualified equipment to China power industry.

High Precision Ultrasonic Guided Wave Technique for Inspection of Power Transmission Line

Due to the merits of high inspection speed and long detecting distance, Ultrasonic Guided Wave（UGW） method has been commonly applied to the on-line maintenance of power transmission line. However, the guided wave propagation in this structure is very complicated, leading to the unfavorable defect localization accuracy. Aiming at this situation, a high precision UGW technique for inspection of local surface defect in power transmission line is proposed. The technique is realized by adopting a novel segmental piezoelectric ring transducer and transducer mounting scheme, combining with the comprehensive characterization of wave propagation and circumferential defect positioning with multiple piezoelectric elements. Firstly, the propagation path of guided waves in the multi-wires of transmission line under the proposed technique condition is investigated experimentally. Next, the wave velocities are calculated by dispersion curves and experiment test respectively, and from comparing of the two results, the guided wave mode propagated in transmission line is confirmed to be F（1,1） mode. Finally, the axial and circumferential positioning of local defective wires in transmission line are both achieved, by using multiple piezoelectric elements to surround the stands and send elastic waves into every single wire. The proposed research can play a role of guiding the development of highly effective UGW method and detecting system for multi-wire transmission line.

X-BAND CIRCULARLY POLARIZED RECTENNAS FOR MICROWAVE POWER TRANSMISSION APPLICATIONS

Circularly polarized rectennas operating at X-band are studied in this paper. The quasi-square patches fed by aperture coupling are used as the circularly polarized receiving antennas, which are easily matched and integrated with the circuits of rectennas. The double-layer structure not only minimizes the size of the rectennas but also decreases the effects of the circuits on the an- tenna. The receiving elements have broader bandwidth and higher gain than the single-layer patches. Two rectennas operating at 10GHz are designed, fabricated and measured. The voltage of 3.86V on a load of 200? is measured and a high RF-DC conversion efficiency of 75% is obtained at 9.98GHz. It is convenient for this kind of rectennas to form large arrays for high power applications.

Vibration Characteristics and Power Transmission of Coupled Rectangular Plates with Elastic Coupling Edge and Boundary Restraints

Coupled-plate structures are widely used in the practical engineering such as aeronautical,civil and naval engineering etc.Limited works can be found on the vibration of the coupled-plate structure due to the increased mathematical complexity compared with the single plate structure.In order to study analytically the vibration characteristics and power transmission of the coupled-plate structure,an analytical model consisting of three coupled plates elastically restrained along boundary edges and elastically coupled with arbitrary angle is considered,in which four groups of springs are distributed consistently along each edge of the model to simulate the transverse shearing forces,bending moments,in-plane longitudinal forces and in-plane shearing forces separately.With elastic coupling condition and general boundary condition of both flexural and in-plane vibrations taken into account by setting the stiffness of corresponding springs,the double Fourier series solution to the dynamic response of the structure was obtained by employing the Rayleigh-Ritz method.In order to validate the model,the natural frequency and velocity response of the model are firstly checked against results published in literatures and the ANSYS data,and good agreement was observed.Then,numerical simulation of the effects of several relevant parameters on the vibration characteristics and power transmission of the coupled structure were performed,including boundary conditions,coupling conditions,coupling angle,and location of the external forces.Vibration and energy transmission behaviors were analyzed numerically.The results show that the power transmission can be significantly influenced by the boundary restraints and the location of excitation.When the excitation is located at the central symmetry point of the model,the energy flow shows a symmetrical distribution.Once the location deviates from the central symmetry point,the power circumfluence occurs and the vortex energy field is formed at high frequency.

Reduction of electric field strength by two species of trees under power transmission lines

Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical pollution.Shielding effects on the electric field strength under transmission lines by two tree species,Populus alba and Larix gmelinii,were examined in this study.The electrical resistivity at different heights of trees was measured using a PiCUS sonic tomograph,which can image the electrical impedance for trees.The electric field strength around the trees was measured with an elf field strength measurement system,HI-3604,and combined with tree resistivity to develop a model for calculating the electric field intensity around trees using the finite element method.In addition,the feasibility of the finite element method was confirmed by comparing the calculated results and experimental data.The results showed that the trees did reduce the electric field strength.The electric field intensity was reduced by 95.6%,and P.alba was better than L.gmelinii at shielding.

Analysis of the compound split transmission based on the four-port power split device

In order to identify all the appropriate system schemes for the compound split systems formed primarily with a four-port mechanical power split device, power transmission characteristics of the compound split systems was analyzed. Considering the structural symmetry and according to the different connection arrangement of the four ports, compound split system was classified into four types. Using black-box modeling method, the generalized models of the speed ratio, the torque ratio and the power split ratio were established. Moreover, a semi-invert diagram was used to distin- guish the different schemes in each type. The characteristics of the speed ratio, the torque ratio and the power split ratio in each domain were also analyzed and compared. Through the semi-invert dia- gram, a selection method based on the rated-power speed ranges in different schemes was presented and all suitable compound split systems were identified, which can be used as references for the scheme selection of this kind of continuously variable power split transmission.

Scenario Based Transmission Power Control (TPC) Analysis over Wireless Body Area Network (WBAN)

In the modern age, Wireless Body Area Network (WBAN) becomes very popular everywhere for monitoring healthcare services remotely. However, the WBAN system has lagged in efficient power consumption till now. As WBAN is formed with several portable devices, low power consumption will ensure battery lifetime. In this paper, an analysis of Transmission Power Control (TPC) over WBAN has been conducted. A ZigBee based WBAN model with different network topologies and data rates has been proposed in the experiment. WBAN data-management technique has been proposed due to reducing more data transmission. Less data transmission reduces overall power consumption. The whole work has been done using OPNET and OMNET++ network simulators. Six sensor nodes have been used with a ZigBee coordinator in the simulation scenario where throughput, load, delay, data traffic, amount of power consumption, packet delivery ratio, etc. have been used as simulation parameters. TPC analysis indicates the power consumptions in different topologies, with different data rates. Several simulation scenarios were run and the results were analyzed in this paper.

Study on Wireless Power Transmission for Gastrointestinal Microsystems Based on Inductive Coupling

Wireless power transmission based on inductive coupling for remotely implanted micro devices has been considered in this paper. The receiving coil, integrated in microsystems and the external transmitting coil compose a loosely coupled transformer. The coupling coefficient was calculated and measured on spacing misalignments. The geometric size of transmitting coil was analyzed for the target of remotely delivering power. The received power was maximized by choosing appropriate value of frequency, tuning capacitance and the load resistance. A conventional full bridge rectifier circuit was employed to convert ac to dc voltage. The received dc power was up to 160 mW with a transmitting vohage of 5 Vrms when the receiving coil was placed at the center of the transmitting coil. This may meet the requirement of some microsystems for high power over a long time.

A Theoretical Model for the Asymmetric Transmission of Powerful Acoustic Wave in Double-Layer Liquids

A theoretical model which couples the oscillation of cavitation bubbles with the equation of an acoustic wave is utilized to describe the sound fields in double-layer liquids, which can be used to realize the asymmetric transmission of acoustic waves. Numerical simulations show that the asymmetry is related to the properties of the host liquids and the input acoustic wave. Asymmetry can be enhanced if the maximum number density or the ambient radius of the cavitation bubbles in the low cavitation threshold liquid increases. Moreover, the direction of rectification will be reversed if the amplitude of the input acoustic wave becomes high enough.

Battery Charger for Electric Vehicles based on a Wireless Power Transmission

In this paper,the case of a battery charger for electric vehicles based on a wireless power transmission is addressed.The specificity of every stage of the overall system is presented.Based on calculated and measured results,relevant capacitive compensations of the transformer and models are suggested and discussed in order to best match the operating mode and aiming at simplifying as much as possible the control and the electronics of the charger.

Multi-Constrained QoS Opportunistic Routing by Optimal Power Tuning in Low Duty-Cycle WSNs

Designing a multi-constrained QoS (Quality of service) communication protocol for mission-critical applications that seeks a path connecting source node and destination node that satisfies multiple QoS constrains such as energy cost, delay, and reliability imposes a great challenge in Wireless Sensor Networks (WSNs). In such challenging dynamic environment, traditional routing and layered infrastructure are inefficient and sometimes even infeasible. In recent research works, the opportunistic routing paradigm which delays the forwarding decision until reception of packets in forwarders by utilizing the broadcast nature of the wireless medium has been exploited to overcome the limitations of traditional routing. However, to guarantee the balance between the energy, delay and reliability requires the refinement of opportunistic routing through interaction between underlying layers known as cross-layer opportunistic routing. Indeed, these schemes fail to achieve optimal performance and hence require a new method to facilitate the adoption of the routing protocol to the dynamic challenging environments. In this paper, we propose a universal cross-layered opportunistic based communication protocol for WSNs for guaranteeing the user set constraints on multi-constrained QoS in low-duty-cycle WSN. Extensive simulation results show that the proposed work, Multi-Constrained QoS Opportunistic routing by optimal Power Tuning (MOR-PT) effectively achieves the feasible QoS trade-off constraints set by user by jointly considering the power control and selection diversity over established algorithms like DSF [1] and DTPC [2].

Analysis of DC Power Transmission Using High T_c Superconducting Cables

A conceptual superconducting DC cable model is designed and its magnetic fields distribution is analyzed with Ansoft/Maxwell soft. A DC Power transmission system is also studied by using the Matlab/Simulink. With the DC Line and AC Ground Fault, the system losses analysis is introduced.The analysis results mainly include the magnetic fields distribution of the HTS cable model with Ansoft/Maxwell, the system loss, the DC Line and AC Ground Fault with Matlab/Simulation.

CHAOTIC OSCILLATION OF ANONLINEAR POWER SYSTEM

For a nonlinear power transmission system, the residue calculus method is introduced and applied to study its heteroclinic bifurcation. There a cone region and a strip region of parameters are obtained, in which the power transmission system displays chaotic oscillation. This gives a theoretic analysis and a computational method for the purpose to control the nonlinear system with deviation stably running.

Rate-aware optimal transmission power analysis in wireless ad hoc networks

The problem of transmission power control in a rate-aware way is investigated to improve the throughput of wireless ad hoc network. The behavior of basic IEEE 802.11 DCF is approximated by the p-persistent CSMA through a Markov chain model. The throughput model takes hidden terminals, muhi-hop flow and concurrent interference into account. Numerical results show that the optimal transmission power derived from this model could balance the tradeoff between spatial reuse and data rate and hence yield maximum throughput.

Power authorization by adding digital controller to electrical equipment

Unpredicted load behaviour troubles traditional power system and becomes a main unstable factor. This paper pro poses a digitalized power system based on synthetical transmission carrier which makes the power system also serves as a data communication system with the same structure. Loads get authorized before powered on, so their behaviour is predictable. Digitalized power system includes such basic units as digital power source, hub and load. Their concepts are explained, their behaviour and implements arc also described in detail. Real time distribution of residual power is applied, which makes prompt authorization possible. Communication protocol and load address assignments are also presented in this paper. A prototype is built and the results verify the effect of the new proposed power system.

Theoretical Design of Energy Harvesting Module or Wireless Power Transmission Receiver Using Magnetic Field of 0.2 mT at 60 Hz

This paper presents a theoretical design method for a magnetic energy harvesting module. This module consists of an air-core coil and resonant capacitor. With a simple RLC circuit model, it can derive an equation of harvesting energy as a function of coil size. In order to demonstrate the magnetic field, a uniform magnetic field is generated by the developed coil system. From the experimented results, it is successfully demonstrated 100 mW of energy harvesting from a magnetic field of 0.09 mT at 60 Hz. This value is in good agreement with the estimated results. Harvested energy is proportional to the square of the magnetic flux density. However, ICNIRP2010 provides a guideline that an acceptable level for human health in a public space is 0.2 mT at power-line frequency. This paper also discuss the possibilities of several applications related with both magnetic energy harvesting and wireless power transmission.

The Sixth International Conference on Fluid Power Transmission and Control(ICFP'2005)

Date: April 12-15, 2005 Venue: Zhejiang University, Hangzhou, P. R. China Organized by Institute of Mechatronic Control Engineering, Zhejiang University

Retro-reflective Beamforming Technique with Applications in Wireless Power Transmission

Retro reflective beamforming technique has the potential of enabling efficient wireless power transmission over long distance(on the order of meters and even kilometers).In retro reflective beamforming,wireless power transmission is guided by pilot signal:Based upon pilot signal broadcasted by a wireless power receiver,a wireless power transmitter delivers focused microwave power beam(s)onto the location of wireless power receiver.When the wireless power receiver’s location is not fixed or when the wireless power receiver’s location is unknown to the wireless power transmitter,the microwave power beam would follow the wireless power receiver’s location dynamically as long as the wireless power receiver broadcasts pilot signal periodically.This paper reviews our research endeavors in recent years on retro reflective beamforming technique targeting three applications:(1)wireless charging for low power mobile/portable electronic devices,(2)space solar power satellites(SSPS)application,and(3)wireless charging in fully enclosed space.The feasibility and potential of retro reflective beamforming technique with applications in wireless power transmission are demonstrated by some preliminary experimental results.