Selective Area Growth and Characterization of GaN Nanorods Fabricated by Adjusting the Hydrogen Flow Rate and Growth Temperature with Metal Organic Chemical Vapor Deposition

CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposition （MOCVD）. The SAG template is obtained by nanospherical-lens photolithography. It is found that increasing the flow rate of 1-12 will change the CaN crystal shape from pyramid to vertical rod, while increasing the growth temperature will reduce the diameters of GaN rods to nanometer scale. Finally the CaN nanorods with smooth lateral surface and relatively good quality are obtained under the condition that the H2：N2 ratio is 1：1 and the growth temperature is 1030℃. The good crystal quality and orientation of GaN nanorods are confirmed by high resolution transmission electron microscopy. The cathodoluminescence spectrum suggests that the crystal and optical quality is also improved with increasing the temperature.

Tentative tariff rate for partial import and export products adjusted

The tentative tariff rate for partial import and export products was adjusted since November 1^(st) of 2006.Total 58 imported commodities will be imposed lower tentative

Design and experimental analysis of rice pneumatic seeder with adjustable seeding rate

To adapt to the diversity of hybrid rice and meet its requirements of precision seeding,a rice pneumatic seeder with adjustable seeding rates was designed in this study.The seeder employed an independent vortex pump to provide the air source for the seed metering device.According to the requirements of air flow in the seed metering device,a sub-pipeline and a general pipeline were designed.The performances of the two types of pipelines were verified by the air pressure uniformity tests.The results showed that the sub-pipeline can distribute the air pressure more evenly than the general pipeline.The coefficient of variation of the sub-pipeline pressure was less than 5%.Wuyou 1179 hybrid rice was selected as the experimental object.The field seeding tests were carried out with different negative pressures and different numbers of groups of sucking holes as experimental factors.The results showed that the average qualified rate of seeding was 93.35%when only 2 groups of sucking holes were working under the seed sucking negative pressure of 2.0 kPa.The average qualified rate of seeding was 87.21%when 3 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The average qualified rate of seeding was 83.73%when 4 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The average qualified rate of seeding was 79.86%when 5 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The main factors affecting the seeding effect were analyzed and the feasibility of a rice pneumatic seeder with adjustable seeding rates was verified by field tests.The research results can provide a basis for its practical production and application.

Dynamic discharging characteristics of absorption thermal battery under different capacity regulation strategies

Thermal battery plays an important role in renewable energy utilization towards carbon neutrality.The novel absorption thermal battery(ATB)has excellent performance but suffers from serious capacity attenuation.To address this problem,two capacity regulation methods,i.e.,variable solution flow and variable cooling water flow,are proposed to achieve a demanded discharging rate.The effects of the two regulation strategies on the dynamic discharging characteristics and overall storage performance are comparatively investigated.To demon-strate the adjustability of the output capacity,several stable discharging rates are successfully maintained by the proposed methods.To maintain a higher discharging rate,the stable discharging time has to be sacrificed.As the demanded output increased from 0.5 kW to 6.0 kW,the stable discharging time decreased from 781.8 min to 27.9 min under variable solution flow and from 769.9 min to 30.7 min under variable cooling water flow.With the increase of solution or water flow rate,the energy storage density is improved,while the energy storage efficiency is slightly increased first and decreased later.The regulation method of variable water flow shows relatively lower energy storage efficiency due to the larger pump power.This study could facilitate reasonable development and application of ATB cycles.

COVID-19 case fatality risk by age and gender in a high testing setting in Latin America: Chile, March-August 2020

Background:Early severity estimates of coronavirus disease 2019(COVID-19)are critically needed to assess the potential impact of the on going pandemic in differe nt demographic groups.Here we estimate the real-time delayadjusted case fatality rate across nine age groups by gender in Chile,the country with the highest testing rate for COVID-19 in Latin America.Methods:We used a publicly available real-time daily series of age-stratified COVID-19 cases and deaths reported by the Ministry of Health in Chile from the beginning of the epidemic in March through August 31,2020.We used a robust likelihood function and a delay distribution to estimate real-time delay-adjusted case-fatality risk and estimate model parameters using a Monte Carlo Markov Chain in a Bayesian framework.

Analysis and Design of Hybrid Excitation Permanent Magnet Synchronous Generators

On the basis of a conventional permanent magnet(PM)synchronous generator’s construction,a novel kind of Hybrid Excitation Permanent Magnet Synchronous Generator(HEPMSG)is introduced by inserting exciting winding in the stator or rotor.Firstly,the construction of HEPMSG is improved with the addition of PM excitation on the ferromagnetic pole,and its working principle and design method are studied in detail.Then,an appropriate exciting current control system is presented considering the characteristics of HEPMSG.Finally,a prototype is made,and test results confirm the analysis and design.