TiO2光催化还原Cu2+

采用溶胶-凝胶法制备出TiO2光催化剂,在紫外光的作用下进行光催化还原Cu2 反应。结果表明:在本实验条件下,TiO2最佳投加量为50mg;在pH=6.0时Cu2 光催化还原效果最好;Cu2 浓度小于7.8mg/L时,光催化还原率增加,而Cu2 浓度大于7.8mg/L时,光催化还原率降低;Cu2 浓度小于7.8mg/L时,最佳空穴捕获剂为木糖,木糖添加量控制在反应液体积10%以内;Cu2 浓度大于7.8mg/L时,最佳空穴捕获剂为苯酚,苯酚添加量也应控制在反应液体积10%以内。     

一种新型三维仿生扑翼机构设计与分析

以昆虫翅膀运动机理为基础,提出了一种复合3种运动的仿生扑翼新机构。由于能使翼尖按8字形或香蕉形运动及机翼扭转,同时可保证两翼的运动对称,使扑翼运动更符合昆虫运动形态。为了实现生物运动轨迹,建立了机构参数的优化模型,并据此设计了扑翼微型飞行器样机,其扑动规律能更逼真地模拟昆虫翼的扑动形态,为新型微型飞行器的设计提供样机。     

投影栅相位法视觉检测技术研究

提出了一种新型的投影栅和相位法视觉检测系统,该系统由投射器将具有正弦分布的条纹投射到被测物体表面,利用不同方位投射条纹的相位来确定双目立体视觉中的对应匹配点。文中对该视觉检测系统进行了标定,建立了双目视觉传感器的三维测量数学模型,标定结果的平均误差为0.039 6mm,均方差为0.023 1mm,角度相对误差为0.2％。最后不仅给出了V型体表面测量的结果,角度相对误差为0.22％,同时还给出了V型体的三维重建图。     

N-(5-硝基-6-氯-3-吡啶甲基)邻苯二甲酰亚胺的合成

研究了N-(5-硝基-6-氯-3-吡啶甲基)邻苯二甲酰亚胺的合成方法。该法先在室温条件下以邻苯二甲酰亚胺与氢氧化钾反应合成了邻苯二甲酰亚胺钾。然后在70°C条件下,以邻苯二甲酰亚胺钾作为亲核试剂,与2-氯-5-氯甲基吡啶发生缩合反应,制备了N-(6-氯-3-吡啶甲基)邻苯二甲酰亚胺。缩合产物再经过硝化,合成N-(5-硝基-6-氯-3-吡啶甲基)邻苯二甲酰亚胺,其熔点为143.1~143.8°C,收率为90.5%。用红外光谱(IR)、核磁共振氢谱(1HNM R)、气谱-质谱(GC-M S)解析以确定中间体和产物的结构;用高效液相色谱测定合成产物的含量。实验结果表明合成了具有较高含量和较高收率的产品。     

Ti-15-3超塑性研究

Ti-15V-3Cr-3Sn-3Al合金是一种在航空航天工业领域具有广泛应用前景的亚稳定β型钛合金。本文用恒应变速率法进行实验,测试Ti-15-3板材的超塑性,为超塑成形提供参考依据。     

First spaceborne demonstration of BeiDou-3 signals for GNSS reflectometry from CYGNSS constellation

The full constellation of Chinese Global Navigation Satellite System (GNSS) BeiDou-3 has been deployed completely and started fully operational service. In addition to providing global Positioning, Navigation and Timing (PNT) services, the BeiDou-3 satellites transmissions can also be used as the sources of illumination for Earth Observation (EO) with a bistatic radar configuration. This innovative EO concept, known as GNSS reflectometry (GNSS-R), allows to measure the Earth surface characteristics at high resolution via the reflected L-band radar signals collected by a constellation of small, low cost and low Earth orbiting satellites. For the first time in orbit, earth reflected BeiDou-3 signal has been detected from the limited sets of raw data collected by the NASA’s Cyclone GNSS (CYGNSS) constellation. The feasibility of spaceborne BeiDou-3 reflections on two typical applications, including sea surface wind and flooding inundation detection, has been demonstrated. The methodology and results give new strength to the prospect of new spaceborne GNSS-R instruments and missions, which can make multi-GNSS reflectometry observations available to better capture rapidly changing weather systems at better spatio-temporal scales.     

基于Mn3+浓度和形貌控制的高性能LiNi0.5Mn1.5O4正极材料

为了改善高电压镍锰酸锂(LiNi_(0.5)Mn_(1.5)O_4)材料的电化学性能,提出利用退火热处理过程调控Mn~(3+)含量和材料形貌来制备LiNi_(0.5)Mn_(1.5)O_4正极材料。LiNi_(0.5)Mn_(1.5)O_4材料的电性能是材料结构、形貌等多因素影响的结果。退火热处理有助于Mn~(3+)氧化成Mn~(4+),实现Mn~(3+)含量调控。退火后材料的空间结构由Fd3m向P4_332转变,且具有微米级多面体形貌,有效提高了循环稳定性和放电平台。研究表明:700℃退火保温15 h合成的材料在20 C下具有118 mAh·g~(-1)放电比容量,循环100次容量保持率提高到92.8%。因此,通过优化Mn~(3+)含量、控制材料形貌可以实现高性能LiNi_(0.5)Mn_(1.5)O_4材料制备。     

Periodic attitude motions along planar orbits in the elliptic restricted three-body problem

A way to improve the accuracy of the three-body problem model is taking into account the eccentricity of primary attractors. Elliptic Restricted Three-Body Problem (ER3BP) is a model for studying spacecraft trajectory within the three-body problem such that the orbital eccentricity of primaries is reflected in it. As the principal cause of perturbation in the employed dynamical model, the primaries eccentricity changes the structure of orbits compared to the ideal Circular Restricted Three-Body Problem (CR3BP). It also changes the attitude behavior of a spacecraft revolving along periodic orbits in this regime. In this paper, the coupled orbit-attitude dynamics of a spacecraft in the ER3BP are exploited to find precise periodic solutions as the spacecraft is considered to be in planar orbits around Lagrangian points and Distant Retrograde Orbits (DRO). Periodic solutions are repetitious behaviors in which spacecraft whole dynamics are repeated periodically, these periodic behaviors are the main interest of this study because they are beneficial for future mission designs and allow delineation of the system’s governing dynamics. Previous studies laid the foundation for spacecraft stability analysis or studying pitch motion of spacecraft in the ER3BP regime. While in this paper, at first, initial guesses for correction algorithms were derived through verified search methods, then correction algorithms were used to refine calculated orbit-attitude periodic behaviors. Periodic orbits and full periodic solutions are portrayed and compared to previous studies and simpler models. Natural periodic solutions are valuable information eventuate in the longer functional lifetime of spacecraft. Since the problem assumption considered in this paper is much closer to real mission conditions, these results may be the means to use natural bounded motions in the actual operational environment.     

低轨卫星的北斗反射信号海洋覆盖分析

北斗系统作为我国自行研制的导航系统，具有独特的混合星座特性，其反射事件在海洋上的空间分布和覆盖性能的研究成果较少。针对上述问题，模拟了北斗三号（Beidou System 3，BDS3）以及全球定位系统（Global Positioning System，GPS）空间星座，模拟不同性能参数的低轨接收卫星，在此仿真系统的基础上，计算反射事件在各仿真场景下的海洋覆盖率以及同时发生反射事件的卫星数量。结果表明：BDS3与GPS相比具有更大的反射事件海洋覆盖率，覆盖性能更优；仿真周期7天与1天相比,前者卫星产生的反射事件海洋覆盖率约为后者5倍；低轨道卫星（Low Earth Orbit,LEO）轨道高度越高，天线波束角度越大，反射事件海洋覆盖率越大；3颗LEO卫星下同时发生反射事件卫星数的平均值约为单颗LEO卫星的3倍。可通过设计多星组网来提高反射事件海洋覆盖率。研究结果对星载反射技术海洋遥感应用方面有一定的参考价值。     

Inter-satellite calibration of FengYun 3 medium energy electron fluxes with POES electron measurements

We perform an L-shell dependent inter-satellite calibration of FengYun 3 medium energy electron measurements with POES measurements based on rough orbital conjunctions within 5?min?×?0.1?L?×?0.5 MLT. By comparing electron flux data between the U.S. Polar Orbiting Environmental Satellites (POES) and Chinese sun-synchronous satellites including FY-3B and FY-3C for a whole year of 2014, we attempt to remove less reliable data and evaluate systematic uncertainties associated with the FY-3B and FY-3C datasets, expecting to quantify the inter-satellite calibration factors for the 150–350?keV energy channel at L?=?2–7. Compared to the POES data, the FY-3B and FY-3C data generally exhibit a similar trend of electron flux variations but more or less underestimate them within a factor of 5 for the medium electron energy 150–350?keV channel. Good consistency in the flux conjunctions after the inter-calibration procedures gives us certain confidence to generalize our method to calibrate electron flux measurements from various satellite instruments.