MOCVD growth of AlGaInP/GaInP quantum well laser diode with asymmetric cladding structure for high power applications

In order to improve the characteristics of the general broad-waveguide 808-nm semiconductor laser diode （LD）, we design a new type quantum well LD with an asymmetric cladding structure. The structure is grown by metal organic chemical vapor deposition （MOCVD）. For the devices with 100-ttm-wide stripe and 1000-/zm-long cavity under continuous-wave （CW） operation condition, the typical threshold current is 190 mA, the slope efficiency is 1.31 W/A, the wall-plug efficiency reaches 63%, and the maximum output power reaches higher than 7 W. And the internal absorption value decreases to 1.5 cm^-1.

Application of Soft Power Strategy on Asian Civilization Spaces

While increasing contact between peoples and cultures,globalization does not weaken the diversity of world's civilizations.Soft power can serve as a lubricant to prevent the clash of civilizations and enhance dialogues between civilizations.The article summarizes the three components of China's soft power:cultural promoting,foreign assistance and the thought of"a harmonious world."Taking Uzbekistan as an example,the author also illustrates the path of the Islamic nations to implement"soft power"strategy.

New LNK302 Addresses Lower Power Home Appliance and Industrial Applications

SAN JOSE,Calif.-September 9,2004-Power Integrations,Inc.(NASDAQ:POWI),the leading supplier of high-voltageanalog integrated circuits used in power conversion, todayintroduced LNK302,a new member of the company'sLinkSwitch-TN family of AC- DC power conversion ICs.Designed as a cost-effective replacement for bulky,energy-wasting capacitive droppers and linear transformers,the LinkSwitch-TN family is ideal for use in home applianceand industrial control applications.The addition of

REMOTE SENSING APPLICATION RESEARCH OF WATER POWER AT THE INITIAL EXPLOITING STAGE IN THE LOWER REACHES OF YALONG RIVER

There are abundant water power resources in the Yalong River which are suitable for the large hydroelectric engineering. But a reliability study should be made for the valley which liable to frequent earthquakes. The color infrared aerophotos, multi-spectral photography and thermal infrared scanning had been specially done besides MSS image, processing. Researches on remote sensing applications to engineering geology, hydrogeology, deformation of neo-tectonics, Iandslide, mud-rock flow, ecological environment and geographical information system had been carried out by more than 20 research units.

Thermal management by manipulating electromagnetic parameters

Electromagnetic absorbing materials may convert electromagnetic energy into heat energy and dissipate it.However,in a high-power electromagnetic radiation environment,the temperature of the absorbing material rises significantly and even burns.It becomes critical to ensure electromagnetic absorption performance while minimizing temperature rise.Here,we systematically study the coupling mechanism between the electromagnetic field and the temperature field when the absorbing material is irradiated by electromagnetic waves.We find out the influence of the constitutive parameters of the absorbing materials(including uniform and non-uniform)on the temperature distribution.Finally,through a smart design,we achieve better absorption and lower temperature simultaneously.The accuracy of the model is affirmed as simulation results aligned with theoretical analysis.This work provides a new avenue to control the temperature distribution of absorbing materials.

Role of PV-Powered Vehicles in Low-Carbon Society and Some Approaches of High-Efficiency Solar Cell Modules for Cars

Development of highly-efficient photovoltaic (PV) modules and expanding its application fields are significant for the further development of PV technologies and realization of innovative green energy infrastructure based on PV. Especially, development of solar-powered vehicles as a new application is highly desired and very important for this end. This paper presents the impact of PV cell/module conversion efficiency on reduction in CO2 emission and increase in driving range of the electric based vehicles. Our studies show that the utilization of a highly-efficient (higher than 30%) PV module enables the solar-powered vehicle to drive 30 km/day without charging in the case of light weight cars with electric mileage of 17 km/kWh under solar irradiation of 3.7 kWh/m2/day, which means that the majority of the family cars in Japan can run only by the sunlight without supplying fossil fuels. Thus, it is essential to develop high-efficiency as well as low-cost solar cells and modules for automotive applications. The analytical results developed by the authors for conversion efficiency potential of various solar cells for choosing candidates of the PV modules for automotive applications are shown. Then we overview the conversion efficiency potential and recent progress of various Si tandem solar cells, such as III-V/Si, II-VI/Si, chalcopyrite/Si, and perovskite/Si tandem solar cells. The III-V/Si tandem solar cells are expected to have a high potential for various applications because of its high conversion efficiency of larger than 36% for dual-junction and 42% for triple-junction solar cells under 1-sun AM1.5 G illumination, lightweight and low-cost potentials. The analysis shows that III-V based multi-junction and Si based tandem solar cells are considered to be promising candidates for the automotive application. Finally, we report recent results for our 28.2% efficiency and Sharp’s 33% mechanically stacked InGaP/GaAs/Si triple-junction solar cell. In addition, new approaches which are suitable for automotive applications by using III-V triple-junction, and static low concentrator PV modules are also presented.

Recent Developments of Modulation and Control for High-Power Current-Source-Converters Fed Electric Machine Systems

The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor and offer high fault-tolerant capability for short-circuit faults.Besides,they provide motor friendly waveforms and four-quadrant operation ability.Therefore,they are suitable for high-power applications of fans,pumps,compressors and wind power generation.The purpose of this paper is to comprehensively review recent developments of key technologies on modulation and control of high-power(HP)PWM-CSC fed electric machines systems,including reduction of low-order current harmonics,suppression of inductor–capacitor(LC)resonance,mitigation of common-mode voltage(CMV)and control of modular PWM-CSC fed systems.In particular,recent work on the overlapping effects during commutation,LC resonance suppression under fault-tolerant operation and collaboration of modular PMW-CSCs are described.Both theoretical analysis and some results in simulations and experiments are presented.Finally,a brief discussion regarding the future trend of the HP CSC fed electric machines systems is presented.

Guest Editorial:Special Section on Applications of Power Electronics in Power Systems

Power transformers and steam turbines were the key drivers in the development of the AC power system paradigm at the dawn of the 20 th century, characterized by huge synchronous generators feeding millions of passive loads through large interconnected systems, all of them supervised and controlled from a centralized energy management system(EMS). In the same way, thyristor valves and IGBTs, introduced

Application of piezoelectric transient response in transducer acoustic power measurement

To explore a more convenient method for measuring the focused ultrasound power, a piezoelectric ceramic plate was used to receive ultrasonic signal directly. Due to an acoustic force acts on the surface of piezoelectric ceramic plate, the piezoelectric response was obtained by means of electromechanical analogy, which was composed of voltage response caused by forced vibration and high frequency attenuation response caused by natural vibration. The conversion relationship between output signal of piezoelectric ceramic plate and acoustic power of transducer was analyzed. The envelope of output piezoelectric signal was extracted in twice, and a voltage amplitude curve with sinusoidal distribution that could describe the changes of acoustic power was obtained. Under different drive voltage of transducer, the maximum peak voltage of envelope curve was found respectively. Their squared values were made a linear fitting with acoustic power measured by acoustic power meter, and then the proportional coefficient of theoretical relational expression was calibrated. The experimental results are in good agreement with the theory. The relative error between calibrated theoretical acoustic power and that measured by acoustic power meter was less than 8.7%. The paper can provide a guideline for measuring acoustic power of transducer by using piezoelectric signal.

CNFET-based voltage rectifier circuit for biomedical implantable applications

Carbon nanotube field effect transistor（CNFET） shows lower threshold voltage and smaller leakage current in comparison to its CMOS counterpart. In this paper, two kinds of CNFET-based rectifiers, full-wave rectifiers and voltage doubler rectifiers are presented for biomedical implantable applications. Based on the standard 32 nm CNFET model, the electrical performance of CNFET rectifiers is analyzed and compared. Simulation results show the voltage conversion efficiency（VCE） and power conversion efficiency（PCE） achieve 70.82% and 72.49% for CNFET full-wave rectifiers and 56.60% and 61.17% for CNFET voltage double rectifiers at typical 1.0 V input voltage excitation, which are higher than that of CMOS design. Moreover, considering the controllable property of CNFET threshold voltage, the effect of various design parameters on the electrical performance is investigated.It is observed that the VCE and PCE of CNFET rectifier increase with increasing CNT diameter and number of tubes. The proposed results would provide some guidelines for design and optimization of CNFET-based rectifier circuits.