In this paper, a new high step-up current-fed LLC resonant DC-DC converter with a center-tapped transformer is proposed. By selecting the switching frequency to be lower than, but near to, the series resonant frequency of the LLC resonant tank, soft-switching operation of all semiconductors, i.e., zero voltage switching (ZVS) turn-on of power MOSFETs and zero current switching (ZCS) turn-off of diodes is achieved. This leads to lower electromagnetic interference (EMI) and lower switching losses and improves the converter efficiency. An interleaved structure is used at the primary side. Thus, input current ripple is smaller, and its frequency is twice the switching frequency. Consequently, a smaller input filter is necessary in practice. The converter with 1.2 kW output power and 760 V regulated output voltage with 80-200 V input voltage variations is simulated. The output voltage is regulated by using asymmetric pulse width modulation (APWM) at 200 kHz switching frequency. Finally, a 700-W prototype has been implemented and experimental results are also presented to verify the simulation results.

Several studies about microstructure noise in capital markets have found that it is a vital aspect of a liquid market. In the absence of noise traders trading volume would severely decrease. However, on the other hand, market microstructure noise deviates prices from their fundamental values. In this paper, we separate the microstructure noise from the price process and then we ask whether high frequency estimates of microstructure noise contain a risk factor and whether that risk factor is priced in the market, meaning that stocks that covary with our high-frequency measure of noise tend to get compensated in the form of higher returns. We examine this question through a portfolio switching approach by looking at the returns of portfolios sorted on our high frequency measurement of the magnitude of the market microstructure noise. The results show that the portfolio corresponding to the highest quartile noise outperforms the portfolio with the lowest quartile noise.

Code switching, as an outcome of linguistic contact, can be seen in most of the multilingual societies. The present field study was conducted in Urmia, a multilingual city of Iran. The purpose of the study was to compare the frequency and direction of code switching among female elementary and high-school students representing high, middle, and low social classes. Applying a non-participant observation method, the required data was extracted from the casual conversations of the students through voice recording. The extracted data was then, exposed to statistical analysis using SPSS software. According to the findings, there was a statistically significant relationship between the direction of code switching and social class of the participants, i. e. the dominant code switching direction among high-class was Fasri-Turkish, while students in the low and middle classes mostly switched in the reverse direction. Furthermore, the results showed no significant relationship between sex and frequency of code switching. Also, no significant relationship was observed between sex and direction of code switching neither.

Conventional high-frequency half-bridge inverters are used widely in industrial and domestic utilizations due to their simplicity and controllability. The output power of these inverters, especially in PWM control technique, will be limited to a narrow range if soft-switching attributes such as zero voltage and zero current switching (ZVZCS) are used. In order to solve this problem this paper proposes a new soft-switching high-frequency half bridge inverter, which employs an active quasi-resonant snubber. This inverter, which is controlled by fixed frequency PWM control technique can regulate output power continuously and is designed according to the principals of conventional high-frequency half-bridge inverters. The soft-switching operation condition of the proposed inverter is expanded to wider range than conventional one. Fixed-frequency, 20 kHz, high thermal efficiency induction-heating cookers are some of the potential applications of this new topology which can be used in domestic and industrial applications. Experimental results illustrate the proof of both the verification of simulation results and the feasibility features of the proposed inverter.

Flux-switching permanent magnet (FSPM) machines are novel brushless machines having magnets in the stator and currently are under intensive research due to their novel features, such as simple and robust rotor, flux focusing effect, sinusoidal phase back-EMF, high torque/power density and high efficiency. In this paper, a sensorless high-frequency sinusoidal signal injection scheme for a novel yokeless and segmented armature axial flux-switching sandwiched permanent-magnet motor (YASA-AFFSSPM) is proposed. Firstly, pulsating voltage injection is investigated in detail. In addition, a simpler method (Direct signal process method) for position error signal processing is presented based on pulsating signal injection. The principle and the realization of this method are analyzed in depth. Through experiment, the traditional signal process method and direct signal process method with high-frequency pulsating sinusoidal signal injection are compared to verify the validity these methods.

This paper proposes a 2.4 GHz active mixer without passive inductor for the transceiver system. Taking into account the design requirements of the mixer, a double-balanced down-conversion structure with active inductor and negative resistance is designed. The proposed mixer with 130 nm CMOS technology is designed and simulated using Cadence software at 1.5 V supply voltage. Although we had to compromise conversion gain with linearity, we were able to achieve very high conversion gain with average linearity. Based on the results of post-layout simulations, the conversion gain of 27.57 dB, IIP3 equal to -7.88 dBm, 1-dB compression point equal to -17.34 dBm and IIP2 equal to 44.22 dBm with power consumption of 2.5 mW was obtained for the proposed mixer. The chip size without input and output pads is 95.18 µm × 117.68 µm, which leads to a chip area of 0.0112mm2.

Local sinusoidal modulation of cavity solitons in an injected Vertical-Cavity Surface-Emitting Laser1 above the laser threshold is numerically investigated and their synchronization in a unidirectional interaction regime is discussed. An all-optical frequency switch based on the synchronization of cavity solitons in this regime is proposed and its performance is quantified by two important parameters: 1) external force threshold and 2) response time of the switching. Our study shows that cavity solitons can be used as all-optical frequency switches with a speed that meets the requirements of optical operations.

Active filters are effective for eliminating harmonic currents and improving reactive power due to nonlinear loads and unbalanced sources. In this paper an effective and new method for Control of active filter is investigated. Direct Power Control (DPC) with space vector modulation is employed for this control scheme. Also, the AC line voltage sensors with a virtual flux (VF) estimator are replaced. The control system is resistant to the majority of line voltage disturbances using by the idea of virtual flux and synchronous double reference frame phase-locked loop (SDRF-PLL) approach. Superior advantages of this method are simple algorithm, good dynamic response, constant switching frequency and resistant to the majority of line voltage disturbances. The operation of proposed control strategy is verified in SIMULINK/MATLAB simulation environment. The simulations show that this active filter is effective for eliminating reactive power injected from nonlinear loads and unbalanced sources. (NF) of low noise amplifier (LNA) are compared with each other.