Numerical simulation on magnetohydrodynamic power generation channel of scramjet

The reverse magnetohydrodynamic(MHD)energy bypass technology is a promising energy redis⁃tribution technology in the scramjet system,in augmented with a power generation equipment to supply the neces⁃sary long-distance flight airframe power.In this paper,a computational model of the scramjet magnetohydrody⁃namic channel is developed and verified by using the commercial software Fluent.It is found that when the mag⁃netic induction intensity is 1,2,3,4 T,the power generation efficiency is 22.5%,22.3%,22.0%,21.5%,and decreases with the increase of the magnetic induction intensity,and the enthalpy extraction rate is 0.026%,0.1%,0.21%,0.34%,and increases with the increase of the magnetic induction intensity.The deceleration ef⁃fect of electromagnetic action on the airflow in the power channel increases with the increase of magnetic induc⁃tion intensity.The stronger the magnetic field intensity,the more obvious the decreasing effect of fluid Mach num⁃ber in the channel.The power generation efficiency decreases as the magnetic induction intensity increases and the enthalpy extraction rate is reversed.As the local currents gathering at inlet and outlet of the power generation area,total temperature and enthalpy along the flow direction do not vary linearly,and there are maximum and minimum values at inlet and outlet.Increasing the number of electrodes can effectively regulate the percentage of Joule heat dissipation,which can improve the power generation efficiency.

Channels and Legal Framework for Power Sector Financing in China

Since early 1980s, in particular during the period of "7th and 8th Five-year Plan"(1986- 1995), China’s power sector has adopted successfully the policy of multichannel and diversified financing to raise funds as well as encouraging to introduce foreign funds for its development and has got tremendous achievements. This paper describes the channels and methods to raise funds from both domestic and international market to meet huge demand of funds amounting to 690 billion yuan RMBfor the sector development during "gth Fiveyear Plan" period (1996-2000) in the wake of overall reform and achievements in the past decade. This paper also presents the legal framework supporting to suit for the methods and channels of the financing. Some suggestions have been made.

Highly efficient class-F power amplifier with digital predistortion for WCDMA applications

A digital predistorted class-F power amplifier （PA） using Cree GaN HEMT CGH40010 operating at 2. 12 GHz is presented to obtain high efficiency and excellent linearity for wideband code-division multiple access （ WCDMA ） applications. Measurement results with the continuous wave （CW） signals indicate that the designed class-F PA achieves a peak power-added efficiency （PAE） of 75. 2% with an output power of 39.4 dBm. The adjacent channel power ratio （ACPR） of the designed PA after digital predistortion （DPD） decreases from -28. 3 and -27. 5 dBc to -51.9 and -54. 0 dBc, respectively, for a 4-carrier 20 MHz WCDMA signal with 7. 1 dB peak to average power ratio （PAPR）. The drain efficiency （DE） of the PA is 37. 8% at an average output power of 33. 3 dBm. The designed power amplifier can be aoolied in the WCDMA system.

Power allocation and mode selection methods for cooperative communication in the rectangular tunnel

For the multipath fading on electromagnetic waves of wireless communication in the confined areas,the rectangular tunnel cooperative communication system was established based on the multimode channel model and the channel capacity formula derivation was obtained.On the optimal criterion of the channel capacity,the power allocation methods of both amplifying and forwarding(AF) and decoding and forwarding(DF) cooperative communication systems were proposed in the limitation of the total power to maximize the channel capacity.The mode selection methods of single input single output(SISO) and single input multiple output(SIMO) models in the rectangular tunnel,through which the higher channel capacity can be obtained,were put forward as well.The theoretical analysis and simulation comparison show that,channel capacity of the wireless communication system in the rectangular tunnel can be effectively enhanced through the cooperative technology;channel capacity of the rectangular tunnel under complicated conditions is maximized through the proposed power allocation methods,and the optimal cooperative mode of the channel capacity can be chosen according to the cooperative mode selection methods given in the paper.

Indoor Narrowband Power Lines Channel Characterization

Power line is an efficient media for home area networking communication scenarios. However, it is not designed to transmit data. This causes several perturbations phenomenon for communications technologies over the power cables. This work presents an investigation of the indoor narrowband power lines channel behavior. The load, the transmission line length and the network topology impact are studied using a simple network. A channel response measure campaign has been realized in 13 sites. The channel capacity has been used for channel classification. The measures were classified into 5 classes. It is shown that channel response is mainly impacted by the load impedance. The class distributions are more impacted by the nature of appliances connected into the indoor network.

The Wireless Power Transmission on the Wristto-Forehead Path Based on the Body Channel

The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.However,except for the channel length,different on-body loca-tions of the transmitter and receiver also influence the power supply performance.This paper fo-cuses on the wrist-to-forehead path to show the potential of BC-WPT for the brain bioelectronics such as the brain computer interface device.The channel characteristics from 10 MHz to 60 MHz are measured by a vector network analyzer(VNA)and a prototype BC-WPT system with differ-ent copper electrodes and the lowest power loss locates between-22 dB and-33 dB.Furthermore,the minimum path loss limit is simulated in Advanced Design System(ADS)software and the low-est optimum path loss can reach nearly-13 dB.Finally,a rectifier circuit is also built at the receiv-er side to harvest d.c.voltage.The results show that the open-circuit voltage(OCV)can reach 1.75 V with the transmitter of 50Ωoutput impedance supplying 5V_(pp)sine voltage at 60 MHz when adopt-ing 1 cm-diameter circular electrodes.

Characterization and Modeling Home Power Grid Topologies in PLC Broadband

Home power outlets can be connected in various topologies： derivation, star, cascade. This paper firstly describes the intrinsic behavior of the transfer function of these basic topologies. Secondly, the channel capacities of the three topologies are compared to check if there is a more favorable topology. Many deterministic modeling methods have been developed to compute the transfer function of power line networks but the given examples in the studies correspond only to the derivation topology with branches connected to the direct path between transceivers. Thirdly, this paper evaluates the ability of common modeling methods （multipath and chain matrices） to compute accurately the transfer function of any topology. Modeling the derivation topology with ＂secondary＂ branches and the star topology is shown to be inappropriate with chain matrices based method. Indeed, this method is very sensitive to the uncertainty of the second parameters of the power cables and this induces considerable fading shifts for those topologies. Multipath modeling method produces results agreeing with measurements for any topology.

Adaptive Energy-Efficient Power Allocation for DAS with Imperfect Channel State Information and Antenna Selection

Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Rayleigh fading channel.A novel EE that is defined as the average transmission rate divided by the total consumed power is introduced.In accordance with this definition,an adaptive power allocation(PA) scheme for DAS is proposed to maximize the EE under the maximum transmit power constraint.The solution of PA in the constrained EE optimization does exist and is unique.A practical iterative algorithm with Newton method is presented to obtain the solution of PA.The proposed scheme includes the one under perfect CSI as a special case,and it only needs large scale and statistical information.As a result,the scheme has low overhead and good robustness.The theoretical EE is also derived for performance evaluation,and simulation result shows the validity of the theoretical analysis.Moreover,EE can be enhanced by decreasing the estimation error and/or path loss exponents.

Research on Multichannel Supply Chain Pricing Under Different Dominance

In a multichannel supply chain comprising of dual-channel retailers with both physical and online channels as well as single-channel e-tailers with online channels,a multichannel demand model for e-commerce is constructed based on customer channel preferences,and a Stackerberg game model with price competition dominated by dual-channel retailers and single-channel e-tailers as well as a Bertrand game model with equal rights are established to analyze the impact of different channel rights structures on the price,demand,and profit of the two retailers.The results show that the single-channel e-tailer under the dual-channel retailer-dominated game has the highest profit,and the dual-channel retailer xmder the single-channel e-tailer-dominated game has the highest profit;thus,both retailers should accept the other's dominant channel rights for profit maximization.

A Design of WCDMA RF Transceiver with Its Performance Measuring

A 2-GHz radio frequency transceiver is presented and implemented for third generation mobile communications using wide-band code division multiple access （WCDMA） scheme. Performance measuring systems are introduced for transmitter channel and receiver sensitivity, respectively. The transceiver achieves maximum output power of 22 dBm, dynamic range of 85 dB, adjacent channel power rejection ratio （ACPR） of -41dB@5MHz, and receiver sensitivity of-119.6 dBm for 128-kb/s data at 3.84-Mcps spreading rate. The measured results indicate the conformity to the required commercial 2.0-GHz WCDMA specification and 3GPP requirements.

Strategic Response to a Powerful Downstream Retailer:Difference-Setting Wholesale Pricing Contract and Partial Forward Integration

We study a supply chain consisted of a supplier and both retailers,and the supplier sells a single product through a dominant retailer and a weak retailer.The aggressive bargaining behavior of the dominant retailer brings the supplier much concern and two feasible strategies are presented to respond to that:difference-setting wholesale pricing contract and integration with the weak retailer.We investigate the decisions of supply chain members under each solution and find that,compared to the traditional form,the supplier always benefits from announcing the difference-setting wholesale pricing contract for it not only raises the marginal wholesale profits of both channels but also reduces the market share of the dominant retailer,thus potentially weakening its channel power.In addition,we show that combining with the weak retailer is not a wise choice for suppliers when the dominant retailer with relatively little bargaining power enjoys a large market share.Finally,by comparing the equilibria of these two solutions,we find that the optimal choice for suppliers depends not only on the difference in market share but also on the dominant retailer's bargaining power in the negotiation.