Estimated Output Power Research Articles

Dynamic Equilibrium Analysis and Simulation of Submerged Kuroshio Generator System

This paper presents design of a novel submerged Kuroshio generator system (SKGS) which is suitable for maritime environments near Keelung Sill. The SKGS was combined with a reliable cable design and a simple anchor system at sea, and it could ignore changes of yaw and roll motion through a proper rudder design. An intuitive simulation method adopted MapleSim software to create a rigid structure modeling of the SKGS. Different modeling frameworks for varied cable design and joint positions were adjusted to meet with the system requirements. Therefore, the system requirements of stability, dynamic equilibrium analysis, and motion behavior of the SKGS combined with the cable design were achieved in this study. Furthermore, the motion ranges of surge-axis and heave-axis could be converged within 0.5 m, and the estimated output power of the SKGS could exceed in 55.1 KW.

Numerical study of high impedance T-match antennas for terahertz photomixers

This paper outlines an efficient numerical method to design terahertz photomixers. The simulations are benchmarked using measured power levels from results published in the literature. Next, the method is applied to two new photomixer designs based on the high impedance T-match antenna with bias supply DC-blocking structures for either a uniplanar layout or a multilayer structure for improved device reliability. Manufacturability is favoured by avoiding the use of airbridges, substrate thinning or under-etching. The estimated output power of the improved design is 9.0 $$\upmu \!\text {W}$$ , which is an improvement of three times over the reference photomixer.

A Method to Calculate Output Power for Sheet-Beam Traveling-Wave Amplifiers

A method to estimate output power for sheet-beam traveling-wave amplifiers is presented. Two traveling-wave tubes are calculated by this method, and the results are compared with those of particle-in-cell simulation.

Infrared and hydrophone system for eastimating the output power of high intensity focused ultrasound transducer

Output power of high intensity focused ultrasound (HIFU) transducer is not only important for the safety and efficiency of clinical treatment, but also for therapy planning in medical applications. In the current paper, a method was proposed to estimate output power of HIFU using a hydrophone and infrared system. The proposed method is independent of the thermal and acoustic parameters of the acoustic absorber and the type of transducer that has been measured. This method consisted of five steps. The amplitude absorption coefficient of the medium was measured through the first two steps. Through the second and third steps, we estimated the ratio of the heat capacity per unit volume to the ultrasonic amplitude absorption coefficient of the absorber. In fourth step, the temperature change at the absorber/air was captured by an IR camera, and the temperature change rate (TCR) was used to estimate the intensity based on the parameters measured by the first three steps. In last step, the sound power of HIFU transducer at high driving voltage can be obtained following the relationship between the sound intensity and sound power. The method was proposed and simulated in three 2-D 1.36 MHz-phased arrays and two kinds of absorbers. In last step, the sound power of HIFU transducer at high driving voltage can be obtained following the relationship between the sound intensity and sound power.

The 8th Harmonic Push-Push Oscillator in V Band

In this paper, the 8th harmonic Push-Push oscillator is successfully presented. The Push-Push principle and the excellent harmonic coherency in a microwave resonator are effectively utilized. The proposed oscillator consists of two sub-circuits, a microstrip ring resonator and an output circuit. The concept of the simplified structure harmonic oscillator (SSHO) is adopted in the proposed oscillator. The microstrip ring resonator plays two roles of the common resonator and the power combiner circuit. This kind of Push-Push oscillator has practical advantages of the easy circuit design due to the simple circuit configuration and the miniaturization of the circuit size. Using the Push-Push principle and the effective circuit configuration of the output circuit, the desired 8th harmonic signal is effectively enhanced. This Push-Push oscillator achieves good millimeter-wave oscillation in V band using inexpensively available X band HEMTs. The estimated output power of -6dBm at the frequency of 51GHz is obtained with the phase noise of -93dBc/Hz at the offset frequency of 1MHz.

Fabrication and characterization of bismuth–telluride-based alloy thin film thermoelectric generators by flash evaporation method

Bismuth–telluride-based alloy thin film thermoelectric generators are fabricated by a flash evaporation method. We prepare Bi 0.4Te 3.0Sb 1.6 (p-type) and Bi 2.0Te 2.7Se 0.3 (n-type) powders for the fabrication of the flash evaporated thin films. The overall size of the thin film thermoelectric generators, which consist of seven pairs of legs connected by aluminum electrodes, is 20 mm by 15 mm. Each leg is 15 mm long, 1 mm wide and 1 μm thick. We measure the output voltage and estimate the maximum output power near room temperature as a function of the temperature difference between hot and cold junctions of the thin film thermoelectric generators. In order to improve the performance of the generators, a hydrogen annealing process is carried out at several temperatures from 25 °C to 250 °C. The highest output voltage of 83.3 mV and estimated output power of 0.21 μW are obtained from a hydrogen annealing temperature of T a = 250 °C and a temperature difference of Δ T = 30 K. The hydrogen annealing temperature of T a = 250 °C also results in the best electrical performance for both p-type thin film (Seebeck coefficient = 254.4 μV/K, resistivity = 4.1 mΩ cm, power factor = 15.9 μW/cm K 2) and n-type thin film (−179.3 μV/K, 1.5 mΩ cm, 21.5 μW/cm K 2).

Resonant-cavity InGaN multiple-quantum-well green light-emitting diode grown by molecular-beam epitaxy

A resonant-cavity InGaN/GaN multiple-quantum-well (MQW) light-emitting diode, incorporating a semitransparent Bragg reflector, has been grown by molecular-beam epitaxy. A 30% reflectivity AlGaN/GaN distributed Bragg reflector and a Ni coating were used as bottom and top mirrors, for backside emission. High-resolution x-ray diffraction data reveal high-quality interfaces in both the MQW and the Bragg mirror. Room-temperature electroluminescence is centered at 507 nm, with an estimated output power of 5 μW at 20 mA. The external efficiency is increased by a factor of 12 compared to similar structures without resonant cavity.

High power factor AC/DC/AC converter with random PWM

A three-phase AC/DC/AC converter is presented with a power factor preregulator to improve the power quality in the input side and a pseudorandom noise generator to reduce the emitted acoustic noise and the mechanical vibration for an induction motor drive. The space vector modulation with hysteresis current control for a voltage source rectifier is adopted to simplify the hardware circuit. A control scheme is presented to drive the supply current following the reference current. The amplitude of reference current for the pulsewidth modulation (PWM) rectifier is derived from the DC bus voltage regulator and the estimated output power. Random switching frequency technique for a three-phase PWM inverter system to reduce the annoying tonal noise and resonant vibration from an induction motor is described. By randomly varying the instantaneous PWM switching frequency from one cycle to the next, the frequency distribution of harmonics is spread in a wide frequency range. The major advantage for using such a strategy is the nonrepetitive output spectral characteristic that results in reduction of torque pulsations in motor drive systems. The nearly unity power factor at the three-phase rectifier and the absence of acoustic noise concentrated at the specific tones which is usually present with conventional sinusoidal modulation are verified by the experimental tests.

Gyrotron backward wave oscillator experiments with a relativistic electron beam using an X-band rectangular waveguide

A mildly relativistic electron beam (500keV, 200A, 10ns) injected into an X-band rectangular waveguide immersed in a uniform axial magnetic field (4-10kG) produced magnetically tunable microwave radiation in the 9-13 GHz frequency range with an estimated output power of 1MW. The frequency range and tunability of the radiated microwave agreed with a theoretical model for a gyrotron backward wave oscillator taking into account the low energy component of the beam electron.

Localization of brain electrical activity via linearly constrained minimum variance spatial filtering.

A spatial filtering method for localizing sources of brain electrical activity from surface recordings is described and analyzed. The spatial filters are implemented as a weighted sum of the data recorded at different sites. The weights are chosen to minimize the filter output power subject to a linear constraint. The linear constraint forces the filter to pass brain electrical activity from a specified location, while the power minimization attenuates activity originating at other locations. The estimated output power as a function of location is normalized by the estimated noise power as a function of location to obtain a neural activity index map. Locations of source activity correspond to maxima in the neural activity index map. The method does not require any prior assumptions about the number of active sources of their geometry because it exploits the spatial covariance of the source electrical activity. This paper presents a development and analysis of the method and explores its sensitivity to deviations between actual and assumed data models. The effect on the algorithm of covariance matrix estimation, correlation between sources, and choice of reference is discussed. Simulated and measured data is used to illustrate the efficacy of the approach.

Theoretical analysis of the breakdown voltage in pseudomorphic HFETs

In this paper a two-dimensional (2-D) model based on a solution to the moments of the Boltzmann transport equation is used to study breakdown in pseudomorphic Heterojunction Field Effect Transistors (HFETs). The effects of the energy conservation equation and the space charge effects of generated carriers are studied in the model. The model is then used to study breakdown in GaAs channel and In/sub 0.53/Ga/sub 0.47/As channel HFETs. The model shows that impact ionization breakdown in these structures is dominated by generation in two regions: (1) the high field region near the corner of the gate, and (2) the channel near the top heterojunction. Next, the effect of a thin pseudomorphic layer, which has a high threshold energy for impact ionization, is studied. This layer is shown to significantly improve the breakdown. voltage of the HFET if used properly. Finally the effects of doping on breakdown voltage of these HFETs are studied. This study shows that increased doping can improve the maximum estimated output power of these devices.

Pseudomorphic inverted HEMT suitable to low supplied voltage application

An enhancement-mode pseudomorphic inverted HEMT with short gate length shows superior saturation properties at low drain voltage. Such saturation properties are suitable for low-supplied-voltage applications. High-frequency properties of FETs were also studied, using two types of frequency-dependent measurement systems which represent active load and common-source circuits. It was confirmed that low knee voltage in the static I-V curve is preserved above 100 kHz. The estimated output power for the device is 50% higher than that of conventional pseudomorphic HEMT at supplied voltage of 1 V. >