浅谈新建本科院校的教学质量评价体系中的顶层设计

目前新建本科院校的教学质量问题引起了越来越多的关注,通过对现有资料的分析,可以发现如何构建教学质量的评价体系成为了人们关注的焦点。那么,如何确保构建的教学质量评价体系发挥应有的作用呢?如何保证构建的教学质量评价体系能够如实的反映学校的办学理念,以及中长期发展的需要呢?那么这需要在构建之初,引入顶层设计的理念,对学校的核心理念加以凝练,构建基本框架,完善应有的制度,从而达到当初设立的目的。     

先进刀具技术与航空零件切削加工

刀具材料及其涂料技术的发展促进了刀具切削速度的不断提高,带来了加工效率的变划,进一步带来了加工范围的拓展.     

电磁超介质研究进展

电磁超介质是当前电磁学和物理研究领域中的前沿与热点，文章将左手材料、复合左／右手传输线、光子晶体统一在电磁超介质的体系下进行介绍，并论述了电磁超介质的发展现状。     

交会对接航天员训练电视图像仿真

以航天员对接过程电视图像仿真为应用背景,研究了近地空间复杂光环境下电视摄像机曝光成像特性和人的视觉成像感知特性,提出了一种基于GPU延迟着色模式下的空间图像浮点纹理着色、光饱和特效、调光和高动态映射显示的电视图像实时渲染方法。采用浮点纹理、高斯模糊等方法实现了逼真源成像和特效渲染;基于降采样的图像平均亮度统计,采用光源亮度和像素亮度两种调节模式实现了实时调光仿真,应用色调映射实现了目标图像的视觉感知高动态渲染显示。经工程验证,仿真图像与实飞图像一致,可以满足航天员训练,具有很好的工程应用价值。     

Lunar geophysical parameters inversion based on gravity/topography admittance and particle swarm optimization

This paper presents a FORTRAN computer program. The program as code will be used for lunar parameter inversions based on gravity/topography admittance. This will be done by assuming that the lunar lithosphere is modeled as a thin elastic spherical shell. The parameters discussed here include; load ratio, crustal thickness, subsurface load depth, crustal density and elastic lithosphere thickness. The admittance of the best-fitting model can be found through automatically adjusting misfits between one theoretical admittance and an observed one. The results in this paper indicate that this research’s theoretical model is reasonable for exploring the best-fitting parameters. In addition, this code is not only able to automatically and simultaneously calculate the global optimum solution of the parameters studied, but also performs well in computational speed. The code can be easily modified to include more parameter inversions; such as the inversion for subsurface density anomaly and the case of considering infilling material in some lunar mare basins.     

Characteristics of the seasonal variation of the global tropopause revealed by COSMIC/GPS data

Using the Global Navigation Satellite System (GNSS) radio occultation observations from Formosa Satellite mission-3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) from 2007 to 2012, the climatological characteristics of the global tropopause was studied, with the following features identified. The overall results generally agree with previous studies. The tropopause has an obvious zonal structure, with more zonal characteristics in the Southern Hemisphere than the Northern Hemisphere. The vertical shape of the tropopause is sharp in the tropics and broad in the sub-tropical latitudes, with the sharpest latitudinal gradient in the mid-latitudes of both hemispheres. The global tropopause exists in a large range between 8 km and 17 km (or between 100 hPa and 340 hPa). The highest tropopause is over the South Asian monsoon regions for the entire year. The spatial structure of the tropopause in the polar region is of concentric structure, with an altitude between 7.5 km and 10 km. It is more symmetric in the Antarctic than the Arctic. Differing from other places, the height of the tropopause in the Antarctic is higher in winter as opposed to summer. The tropopause has distinct seasonal variability, especially in polar regions.     

Dry Grinding of Titanium Alloy Using Brazed Monolayer cBN Wheels Coated with Graphite Lubricant

The purpose of this study is to investigate the effect of graphite lubricant on the dry grinding performance of Ti-6Al-4Valloy,using graphite-coated,brazed monolayer,cubic boron nitride(cBN)wheels.Brazed monolayer cBN wheels both with and without a coating of polymer-based graphite lubricant are fabricated and subsequently compared for grinding performance based on measurements of grinding temperature,surface microstructure and grinding.In terms of grinding temperature,considerable improvement in dry grinding performance of titanium alloy is achieved using coated brazed monolayer cBN wheels,with 42%—47%reduction in grinding temperature as opposed to uncoated wheels.The grinding force ratio with the coated wheels is observed to remain between 1.45to1.85despite material removal rates reaching up to 1 950mm3/mm.No tangible change in ground titanium surface microstructure is noted as a result of grinding with the graphite coated wheels as opposed to the uncoated ones.     

Efficiency optimized fuel supply strategy of aircraft engine based on air-fuel ratio control

Accurate fuel injection control of aircraft engine can optimize the energy efficiency of UAV power system while meeting the propeller speed requirement. Traditional injection control method such as open-loop calibration causes instability of fuel supply which brings the risk of power loss of UAV. Considering that the closed-loop control of AFR can ensure a stable fuel feeding, this paper proposes an AFR control based fuel supply strategy in order to improve the efficiency of fuel-powered UAV while obtaining the required engine speed. According to the optimum fuel injection results, we implement fuzzy-PID method to control the set AFR in different situations. Through simulation and experiment studies, the results indicate that, to begin with, the calibrated mathematical model of the aircraft engine is effective. Next, this fuel supply strategy based on AFR control can normally realize the engine speed regulation, and the applied control algorithm can eliminate the overshoot of AFR throughout all the working progress. What is more,the fuel supply strategy can averagely shorten the response time of the engine speed by about two seconds. In addition, compared with the open-loop calibration, in this work the power efficiency is improved by 9% to 33%. Last but not the least, the endurance can be improved by 30 min with a normal engine speed. This paper can be a reference for the optimization of UAV aircraft engine.     

TS-InSAR analysis for monitoring ground deformation in Lanzhou New District,the loess Plateau of China,from 2017 to 2019

Large-scale land creation projects involving the cutting of mountains to infill gullies for construction have been carried out in Lanzhou New District (LZND). However, there is an urgent need for comprehensive and detailed research on the spatiotemporal evolution of ground deformation in LZND. Based on Sentinel-1A SAR data, combined with the urban geological background, the ground deformation in LZND from 2017 to 2019 was analysed. Two independent, multi-temporal techniques, persistent scatterers interferometry (PS-InSAR) and the small baseline subset (SBAS-InSAR), were used to calculate the deformation time series, and the results were cross-verified. The time series-monitoring results of the SBAS and PS calculations exhibited strong consistency in LZND and verified the high reliability of the experimental results. The results showed the whole surface of the LZND from March 2017 to October 2019 maintained stability, and the deformation rate was primarily in the range of ?10 to 10 mm/year. However, ground deformation in the Xicha area was evident. The maximum annual deformation rates monitored by SBAS-InSAR and PS-InSAR were ?52.48 mm/year and ?56.35 mm/year, respectively. The most typical deformation areas include the built-up area and the land creation area. The surface subsidence area was concentrated in the filling area. The ground deformation range of LZND kept expanding and accelerating from 2017 to 2019. Land creation, urban construction, geology and precipitation were the primary factors contributing to local severe ground deformation. The results of this study provide reference for the regional urban planning in LZND.     

带弹性元件扑翼机构的动力学分析及实验

为研究扑翼飞行器传动机构的能量特性，以特拉华大学机械系统实验室所研制样机为原型进行了建模。引入气动项和拉力弹簧建立了完整的动力学模型。分析发现，气动项的力矩峰值为惯性项的4.8倍，对电机的转矩峰值的影响起主要作用。运用正交法进行仿真发现，引入拉力弹簧可以使电机转矩峰值最大降低77.5%，与理论分析相符合。进一步的物理实验验证了理论分析和仿真结果的正确性，并得到了当弹簧的连接点位置为185 mm、原长为200 mm及刚度为0.1 N/mm时实验结果取得最优值，可为扑翼机传动机构的优化设计提供依据。此外，引入弹性元件也可有效降低电机的转速波动，进而为仿生扑翼飞行器的生产和实践应用提供理论指导。