A frequency servo SoC with output power stabilization loop technology for miniaturized atomic clocks

A frequency servo system-on-chip(FS-SoC)featuring output power stabilization technology is introduced in this study for high-precision and miniaturized cesium(Cs)atomic clocks.The proposed power stabilization loop(PSL)technique,incorporating an off-chip power detector(PD),ensures that the output power of the FS-SoC remains stable,mitigating the impact of power fluctuations on the atomic clock's stability.Additionally,a one-pulse-per-second(1PPS)is employed to syn-chronize the clock with GPS.Fabricated using 65 nm CMOS technology,the measured phase noise of the FS-SoC stands at-69.5 dBc/Hz@100 Hz offset and-83.9 dBc/Hz@1 kHz offset,accompanied by a power dissipation of 19.7 mW.The Cs atomic clock employing the proposed FS-SoC and PSL obtains an Allan deviation of 1.7×10^(-11) with 1-s averaging time.

Analysis on Output Power for Multi-direction Piezoelectric Vibration Energy Harvester

To predict the performance of multi-direction piezoelectric vibration energy harvester,an equation for calculating its output power is obtained based on elastic mechanics theory and piezoelectricity theory.Experiments are performed to verify theoretical analysis.When the excitation direction is along Y direction,a maximal output power about 0.139 mW can be harvested at a resistive load of 65kΩ and an excitation frequency of 136 Hz.Theoretical analysis agrees well with experimental results.Furthermore,the performance of multi-direction vibration energy harvester is experimentally tested.The results show that the multi-direction vibration energy harvester can harvest perfect energy as the excitation direction changes in XY plane,YZ plane,XZ plane and body diagonal plane of the harvester.

Reducing the minimum output power of soft-switching inverter arc welding power supplies

The full-bridge zero-voltage and zero-current switching inverter, which can adjust the output power by keeping the duty-cycle of lagging arm constant, changing the duty-cycle of leading arm, is a common circuit topology of soft-switching inverter arc welding power supplies. However, the output power still remains a certain value when the duty-cycle of leading arm decreases to zero. The working-mode of soft-switching inverter and the waveforms of major parameters with the condition of duty-cycle of leading arm being zero are studied in this paper. U-1 characteristic experiments prove that the minimum output power of soft-switching circuit, which depends on the charged voltage of capacitors in parallel with leading arm, can be decreased by reducing the duty-cycle of lagging arm. By switching working-modes between half-bridge and full-bridge, the output power can swing from zero to the power rating.

Controlling the output power of soft switching arc welding inverter by two-stage continuous PWM method

The full bridge zero voltage zero current switching （ FB-ZVZCS ） , which could adjust the output power by keeping the duty ratio of lagging leg constant and changing the duty ratio of leading leg, was a common circuit of soft switching arc welding inverter power source. However, when the duty ratio of leading leg was reduced to zero, the output power stayed the constant value instead of becoming zero. The working status and waveforms of some major parameters were studied in this paper while the duty ratio of leading leg was zero. It was concluded that the minimum output power of soft switching inverter was related to the charging voltage of paraUel capacitors, and the output power also could be reduced by reducing the duty ratio of lagging leg. A novel two-stage continuous PWM control method that could switch working-mode between full bridge and half bridge was put forward in this paper. This kind of control method could further reduce the output power of soft switching inverter in order to meet the requirement of low heat input of sheet metal welding.

Optimal Output Power Control of Switched Reluctance Generator at a Constant Speed

In order to control the output power of a switched reluctance generator(SRG)at a constant speed,the output power of SRG is theoretically analyzed by using freewheeling control.First,through a theoretical analysis,a finite element simulation and an experiment,it was verified that the output power of SRG cannot be improved by using freewheeling control with a single pulse control method(SPCM).Then,the maximum output power can be obtained by optimizing the turn off angles of SPCM at a constant speed,and at the same time,the formula of the optimal turn-off angle was presented,which meets the criterion for the output power maximization.Finally,numerical simulation and experimental results demonstrated the validity of the theoretical analysis.

Development of Surface Grating Distributed Feedback Quantum Cascade Laser for High Output Power and Low Threshold Current Density

We report on the room-temperature cascade laser （QCL） at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback （DFB） quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.

Experimental Study of Buffer Gas Flow Rate Effect on Output Power of a Copper Vapor Laser

A copper vapor laser with active medium length of 60 cm and bore of 16 mm has been operated and optimized using different buffer gases to investigate the effect of the gas flow rates on the output power. It is found that there is a special optimum gas flow rate associated with the type of buffer gas.

Mathematical modeling of output power in RF-excited CO_2 waveguide lasers

Theoretical analysis model has been established for CO 2 laser to describe the process of dynamic emission in the electrooptically Q switched laser .The electron excitation and the energy transfer of vibration level and the rotational relaxation of rotational levels are described. The comparison between this model and a set of coupled rat equations model are discussed.

A novel method for extending the output power back-off range of an asymmetrical Doherty power amplifier

A novel method is proposed to extend the output power back-off(OPBO)range of the Doherty power amplifier(DPA).This study reveals that the OPBO range of the DPA can be extended by tuning the output impedance of the peaking stage away from infinity and changing the phase delay of the output matching network of the carrier power amplifier.Based on this theory,a large-OPBO-range high-efficiency asymmetrical DPA working band from 1.55 to 2.2 GHz(35%relative bandwidth)is designed to verify the proposed method.Experimental results show that the DPA operates from 1.6 to 2.1 GHz.The range of the measured efficiency is 42.2%–52.1%in the OPBO state and 47%–62.7%in the saturation state.The OPBO range is 11.1–13.2 dB.

W-band high output power Schottky diode doublers with quartz substrate

W-band quartz based high output power fix-tuned doublers are analyzed and designed with planar Schot- tky diodes. Full-wave analysis is carried out to find diode embedding impedances with a lumped port to model the nonlinear junction. Passive networks of the circuit, such as the low pass filter, the E-plane waveguide to strip transitions, input and output matching networks, and passive diode parts are analyzed by using electromagnetic simulators, and the different parts are then combined and optimized together. The exported S-parameters of the doubler circuit are used for multiply efficiency analysis. The highest measured output power is 29.5 mW at 80 GHz and higher than 15 mW in 76-94 GHz. The highest measured efficiency is 11.5% at 92.5 GHz, and the typical value is 6.0% in 70-100 GHz.

A 4.69-W/mm output power density InAlN/GaN HEMT grown on sapphire substrate

We report high performance InA1N/GaN HEMTs grown on sapphire substrates. The lattice-matched InA1N/GaN HEMT sample showed a high 2DEG mobility of 1210 cmZ/（V.s） under a sheet density of 2.6 × 10^13 cm^-2. Large signal load-pull measurements for a （2 × 100 μm） x 0.25 μm device have been conducted with a drain voltage of 24 V at 10 GHz. The presented results confirm the high performances reachable by InAIN- based technology with an output power density of 4.69 W/ram, a linear gain of 11.8 dB and a peak power-added efficiency of 48%. This is the first report of high performance InA1N/GaN HEMTs in China's Mainland.

Efficiency and Output Power Evaluation of a Wavelength Converter Based on FWM in a Single Mode Fiber

A frequency domain analysis is presented to determine the performance characteristics of a tunable all-optical wavelength converter using four-wave mixing (FWM) in a single mode fiber (SMF) around the zero dispersion wavelength using two pump lasers. The output converted signal power as well as efficiency evaluated at a bit rate of 10 Gb/s show that the signal power is substantially higher at lower values of wavelength separation.

Local topography-induced pressure gradient effects on the wake and power output of a model wind turbine

Wind-tunnel experiments were performed to study the effect of favorable and adverse constant pressure gradients(PG)from local changes in the topography right downwind of a model wind turbine.Particle image velocimetry was used to characterize the near and intermediate wake regions.We explored five scenarios,two favorable,two adverse PG,and a case with negligible PG.Results show that the PGs induce a wake deflection and modulate the wake.They imposed a relatively small impact on the turbulence kinetic energy and kinematic shear stress but a comparatively dominant effect on the bulk flow on the flow recovery.Based on this,a simple formulation is used to describe the impact of PG on the wake.We modeled the base flow through a linearized perturbation method;the wake is obtained by solving a simplified,integrated streamwise momentum equation.This approach reasonably estimated the flow profile and PG-induced power output variations.

Big-M based MILP method for SCUC considering allowable wind power output interval and its adjustable conservativeness

In contrast to most existing works on robust unit commitment(UC),this study proposes a novel big-M-based mixed-integer linear programming(MILP)method to solve security-constrained UC problems considering the allowable wind power output interval and its adjustable conservativeness.The wind power accommodation capability is usually limited by spinning reserve requirements and transmission line capacity in power systems with large-scale wind power integration.Therefore,by employing the big-M method and adding auxiliary 0-1 binary variables to describe the allowable wind power output interval,a bilinear programming problem meeting the security constraints of system operation is presented.Furthermore,an adjustable confidence level was introduced into the proposed robust optimization model to decrease the level of conservatism of the robust solutions.This can establish a trade-off between economy and security.To develop an MILP problem that can be solved by commercial solvers such as CPLEX,the big-M method is utilized again to represent the bilinear formulation as a series of linear inequality constraints and approximately address the nonlinear formulation caused by the adjustable conservativeness.Simulation studies on a modified IEEE 26-generator reliability test system connected to wind farms were performed to confirm the effectiveness and advantages of the proposed method.

Fabrication of Tm-Doped Fibers for High Power and 121W Output All-Fiber Tm-Doped Fiber Laser

We fabricate the Tm-doped double cladding silica fiber by using the vapor-solution hybrid-doping method, then build up an all-fiber Tin-doped fiber laser which can provide the output power of up to 121 W, corresponding to a slope efficiency of 51% and an optical-optical efficiency of 48%. By using the domestic Tin-doped fiber, it is the first time a hundred-watt level output at 1915nm has been achieved, to the best of our knowledge. The thermal effect of Tm-doped fiber laser is also analyzed.

Decision Technique of Solar Radiation Prediction Applying Recurrent Neural Network for Short-Term Ahead Power Output of Photovoltaic System

In recent years, introduction of a renewable energy source such as solar energy is expected. However, solar radiation is not constant and power output of photovoltaic (PV) system is influenced by weather conditions. It is difficult for getting to know accurate power output of PV system. In order to forecast the power output of PV system as accurate as possible, this paper proposes a decision technique of forecasting model for short-term-ahead power output of PV system based on solar radiation prediction. Application of Recurrent Neural Network (RNN) is shown for solar radiation prediction in this paper. The proposed method in this paper does not require complicated calculation, but mathematical model with only useful weather data. The validity of the proposed RNN is confirmed by comparing simulation results of solar radiation forecasting with that obtained from other

STUDY OF LARGE OUTPUT POWER PIEZOELECTRIC CERAMIC TRANSFORMER

The piezoelectric ceramic transformer has been more and more widely applied in elec tronic devices of high voltage and small current due to its novel features in the high voltage field: very high voltage step-up ratio, small in size, light in weight and non-metal material in use; it cannot be burnt while the load circuit is shorted, and broken down in high voltage field;

Prediction of photovoltaic power output based on different non-linear autoregressive artificial neural network algorithms

Prediction of power output plays a vital role in the installation and operation of photovoltaic modules.In this paper,two photovoltaic module technologies,amorphous silicon and copper indium gallium selenide installed outdoors on the rooftop of the University of Dodoma,located at 6.5738°S and 36.2631°E in Tanzania,were used to record the power output during the winter season.The average data of ambient temperature,module temperature,solar irradiance,relative humidity,and wind speed recorded is used to predict the power output using a non-linear autoregressive artificial neural network.We consider the Levenberg-Marquardt optimization,Bayesian regularization,resilient propagation,and scaled conjugate gradient algorithms to understand their abilities in training,testing and validating the data.A comparison with reference to the performance indices:coefficient of determination,root mean square error,mean absolute percentage error,and mean absolute bias error is drawn for both modules.According to the findings of our investigation,the predicted results are in good agreement with the experimental results.All the algorithms performed better,and the predicted power out of both modules using the Bayesian regularization algorithm is observed to exhibit good processing capabilities compared to the other three algorithms that are evident from the measured performance indices.