In this paper, an ultra-low-noise amplifier with Frequency band switching capability is designed, simulated and fabricated. The two Frequency ranges of this amplifier consist of the 2. 4 to 2. 5 GHz and 3. 1 GHz to 3. 15 GHz Frequency bands. The designed amplifier has a noise figure of less than 1dB, a minimum gain of 23 dB and a VSWR of less than 2 in the whole Frequency band. The design process starts with increasing the stability factor in the source through manipulating the inductor placement technique. Then the input and output matching circuits for the first Frequency band are designed. This process is completed by utilizing two similar stages placed successively in order to achieve the desired gain level. Since no degradation of the noise figure is observed and acceptable values are also obtained for other parameters, switching the elements in the output matching circuit can be a good idea for avoiding the use of a similar circuit for the second Frequency band. The optimum secondary values for the mentioned elements are obtained through the analyses performed using the ADS software. For changing the values of the mentioned elements two MOSFETs are used for adding capacitance and inductance to the matching circuit. In the next step, the designed amplifier is finalized and optimized after adding a suitable bias circuit to it. Moreover, The designed amplifier is fabricated and a good agreement between the measurement, analysis, and simulation results is observed.

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.

In this paper, a double-band hysteresis current controller (DBHCC) as a new switching method in feeder inverter of a BLDC motor is proposed and implemented. Then, it is compared with the single-band hysteresis current controller (SBHCC). It has been shown that in the proposed method, the average switching Frequency of switches is reduced compared to SBHCC by preserving other advantages. Thus, switching losses are reduced and the lifetime of switches is increased. In addition, it has desirable effects on reducing electromagnetic interferences and noise. In addition, speed control, torque, current ripple and transient states are investigated in both states. Three-phase reference currents for hysteresis switching are obtained using a PI regulator and integrating with output signals from Hall-effect sensors. BLDC motors are used widely in the industry due to more advantages in comparison with others. In order to drive this motor, a three-level cascade half-bridge voltage source inverter with constant DC link for each phase is used. Simulation results are obtained and analyzed using MATLAB/Simulink environment.

Introduction: Usually osseointegration takes between three to six months after implant placement but patients are interested to have early loading. There are no definitive criteria for measuring bone mineral density (BMD), insertion torque (IT) (final torque force) and resonance Frequency analysis (RFA) (primary implant stability) to determine exact loading time based on the relationship between the above-mentioned parameters. The aim of this study was to determine the relationship between IT, RFA and BMD in screw-type implants.Materials and Methods: This clinical trial was conducted on 18 patients who were candidates for ITI implant placement. Written consent was taken and jaw bone density was determined via a digital radiography technique before surgery. After implant placement, RFA and IT were measured. Fifty-five ITI implants of the total 62 implants placed were evaluated; the implants were 12 mm long with a diameter of 4.1 mm. Data was analyzed with Pearson’s test using SPSS.15 software (a=0.05).Results: There was a significant relationship between IT, RFA and BMD. Pearson’s test showed a correlation coefficient of 0.872 to 0.789 between the three parameters, indicating a strong relationship between them. The mean bone density was 1.468±0.042 g/cm2; the mean RFA was 66.01±2.2 ISQ and the mean IT was 34.62±3.33 N/cm2.Conclusion: Based on the results of the present study there is a significant relationship between, IT, RFA and BMD (p value=0.001).

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.

In this paper, a Frequency switchable antenna design using genetic algorithms (GAs) for dual band WiMAX (3.5GHz) and WLAN (5.2GHz) applications is proposed. The area of the radiating patch element is divided into 2 mm square cells, with each cell assigned a conducting or non-conducting characteristic. To realize Frequency reconfiguration, switches are incorporated into appropriate locations to activate/deactivate corresponding cells. The on/off states of the switches are represented by the presence or absence of conductor, respectively. Hence, the proposed approach allows the antenna to operate as mono-band or dual-band radiator according to the desired application. Further, measurements and simulations are carried out and a reasonable agreement is achieved.

Earthquake accelerograms are needed for dynamic analysis of structures. Preliminary data obtained from recording instruments may include some errors that their sources and values should be evaluated and corrected appropriately. In this study, at first step, earthquake recording instruments are introduced and explained. Then the noise (error) sources of accelerograms and processing methods of earthquake data are reviewed. Filtering techniques are also assessed from the view point of Earthquake Engineering. For this purpose, different methods for the determination of correction Frequency are reviewed and finally the standard w-2 model introduced by Brune (1970) is selected. In this study, 78 earthquake records are selected from Mahdavians study. In this selection, two parameters are considered:(1) Causative earthquake of the record and(2) The soil type of at recording station. A computer program is developed to calculate Fourier amplitude spectra of three recorded components and to plot them. By comparing the calculated spectra and the standard w-2 model, correction Frequency is determined and then records are corrected using SWS processing software. Effect of different parameters like magnitude, epicenter distance and local site conditions are evaluated. Correction frequencies are estimated and Fourier amplitude spectra are plotted before and after the correction. Finally, several correction Frequency bands are presented for different site conditions of recording stations.