高分一号卫星PMS 相机多场地宽动态辐射定标

为克服卫星遥感器常规定标方法不足,实现GF-1 卫星PMS 相机高精度在轨定标,提出了多场地宽动态辐射定标方法,分析了新方法的不确定度。首先,介绍宽动态辐射定标原理和试验场区概况,设计开展了GF-1 卫星多场地同步观测试验;接着,基于试验数据和宽动态定标模型,实现了GF-1 卫星PMS 相机的在轨辐射定标;最后,讨论GF-1 卫星PMS 相机多场地定标的不确定度和模型的稳定性。结果表明:GF-1 卫星PMS 相机自发射以来辐射响应特性与实验室定标结果相比发生了一定变化,最大变化量达到了7.72%;PMS 相机多场地辐射定标的综合不确定度为5.35%。所获取的PMS 相机定标系数满足遥感辐亮度产品生产的精度要求,且多场地定标可作为后续高分卫星的在轨定标的方法参考。     

GF-4可见光及近红外谱段的辐射定标

"高分四号"是我国高分辨率对地观测系统中唯一一颗地球同步轨道遥感卫星,应用于环境及林火监测等领域。GF-4数据有很高的空间分辨率,但是辐射特性存在偏差从而导致辐射精度并不是很高。为了提高GF-4卫星数据辐射和LandSat8数据为基准影像,以敦煌辐射校正场作为试验区对GF-4可见光及近红外谱段进行交叉辐射定标。结果表明,通过GF-4的DN值与MODIS和LandSat8的表观辐射亮度数据分析对比,的可见光及近红外波段的定标误差均在10%以内;而LandSat8的可见光及近红外波段的定标误差均在5%以内,比的定标精度接近官方定标系数,满足遥感定量需求。     

HJ-1A/B星CCD相机在轨辐射性能检测分析

为检测分析HJ-1A/B星CCD相机在轨辐射探测性能及其辐射定标的有效性,提出了基于多种光学特性地面目标的在轨检测方法。首先,介绍了HJ-1A/B星CCD相机在轨辐射性能检测方法,并基于2013年HJ-1A/B卫星地面同步观测试验数据,获取了HJ-1A/B星过境时刻的卫星入瞳处等效辐亮度。然后以该等效辐亮度为基准,对HJ-1A/B星CCD相机历次在轨辐射定标结果进行检验,分析HJ-1A/B星CCD相机的在轨运行期间辐射探测性能变化趋势。结果表明：HJ-1A/B星在轨运行过程中,辐射性能在不断发生变化;在轨运行5年多时间里,HJ-1A/B星的CCD相机各波段的辐射性能平均衰变量最低为3.7%,最大为39.6%;为保证遥感数据的定量化精度,定期的在轨绝对辐射定标十分必要。     

CBERS-2 CCD相机绝对辐射定标系数验证与评价

卫星遥感器绝对辐射定标系数的有效性检验，是对卫星遥感精度进行全面评价的最有效手段之一。利用绝对辐射定标系数反演反射率值与实测值对比的方法，对CBERS-2CCD相机绝对辐射定标结果进行了有效性检验与误差分析，根据分析结果对CCD相机4个波段的绝对辐射定标系数作出了客观的评价。验证表明，两点法获得的CCD相机定标系数可靠，定标效果较好，而单点法获得的定标系数对CCD相机不适用。     

面阵式极轨卫星对月观测快速预报模型

对月辐射定标是遥感卫星星上定标重要的手段之一,而对月辐射定标的首个关键问题是选取合适的观测时机.提出了一种适用于面阵相机的对月观测快速预报模型,首先通过固定时间步长确定时间窗口的分布范围,随后选取月球在卫星视场方向上的投影圆上的若干等距离的散点,精确判断月球与卫星视场的几何关系,并采用斐波那契搜索法快速计算月球进入、离开相机视场的时间窗口.仿真实验结果表明,所提模型与传统的跟踪传播算法相比,计算量降低,时间性能提高,预报结果更准确.所提方法与Satellite Tool Kit (STK)方法在可视性计算准确度上的平均偏差为亚秒级.     

云相机相对辐射定标技术研究

云相机采用阈值法对观测目标区域进行在轨实时云识别。在云判算法中，辐射度量的准确性将会影响最终的反演结果。本文建立了云相机像元响应值与辐亮度之间的信息模型，针对云相机探测器各像元在入射光均匀一致时，输出响应值出现不相等的情况提出了改进措施。首先，根据云相机的信息模型分析了探测器像元响应值不同的原因，建立了云相机的相对辐射定标模型。然后，由于云相机视场角较大，大口径积分球辐射源出射光也难以一次性覆盖所有视场，在实验中设计了分视场测试的方式。最后，根据相对辐射定标模型和分视场测量方式，进行了云相机的相对辐射定标。实验结果表明：云相机对积分球成像结果校正前非均匀性为6%左右，经相对辐射定标校正后，在轨典型信噪比条件下非均匀性达到1.5%以内，低信噪比条件下达到3.25%。定标测试结果满足云相机设计的指标要求。     

利用多星表交叉外推恒星能量的方法

为了获取满足特定探测器工作谱段的恒星能量,提出了一种基于多星表数据的恒星能量外推方法,利用IRAS、WISE和2MASS星表数据交叉校验,将已有的高精度恒星谱段能量转化为相机的任意工作谱段.该模型简化了外推过程,提高了外推效率,实现对70%的恒星外推精度3%以内,与Cohen等人对Vega和Sirius长期观测得到的结果相同.同时,给出一个可用于辐射定标的星表.在恒星定标时可以根据模型外推结果选择更适合探测器的多恒星数据.     

利用多星表交叉外推恒星能量的方法研究

为了获取满足特定探测器工作谱段的恒星能量,提出了一种基于多星表数据的恒星能量外推方法,利用IRAS、WISE和2MASS星表数据交叉校验,将已有的高精度恒星谱段能量转化为相机的任意工作谱段.该模型简化了外推过程,提高了外推效率,实现对70%的恒星外推精度3%以内,与Cohen等人对Vega和Sirius长期观测得到的结果相同.同时,给出一个可用于辐射定标的星表.在恒星定标时可以根据模型外推结果选择更适合探测器的多恒星数据.     

航天遥感器热红外波段辐射精度分析

根据遥感器的辐射定标方法和计算模型,对遥感器的辐射精度进行了分析。当假设遥感器观测地面目标、冷空间和星上黑体定标源都通过扫描镜成像时,扫描镜的热辐射以及仪器有背景辐射能量不会对辐射精度产生影响,影响遥感器辐射精度的主要因素是遥感器的信噪比、星上定标黑体的比辐射率误差、星上定标黑体的温度测量误差以及中心波长的漂移等因素。     

风云二号卫星水汽波段在轨辐射定标新方法

将月球作为热发射波段定标参考源,在无需月表发射率和温度信息条件下,通过引入UDER参数,建立了不同热发射波段观测辐亮度间定量关系,并导出了新的波段间交叉定标方法.同时,利用FY-2E卫星多波段月球观测结果,以辐射精度较高的热红外波段为基准,在无星载全光路黑体情况下,初步实现了水汽波段在轨高精度辐射定标,且在200～220 K低温区间内的定标精度平均提高约3.5 K,并显著改善了云分类等定量产品的性能.     

Quantum flux parametron with magnetic flux regulator

A magnetic flux regulator for a quantum flux parametron (QFP) is proposed. The regulator is formed with a parallel connection of a Josephson junction across activation inductors building an RF-SQUID (superconducting quantum interference device). This junction makes a nonlinear bypass channel for magnetic activation flux and contributes to regulation of applied flux and elimination of undesirable external noises. Using this flux regulator, the activation condition tolerance is not only improved, but also a higher speed transition from a nonactivated state to an activated state is expected. QFP operations with the regulators have been observed with integrated circuits     

Quantum flux parametron: a single quantum flux device for Josephsonsupercomputer

A quantum flux parametron (QFP), a single quantum flux superconductive device that has a potential of up to 100-GHz switching with nW-order power dissipation, is considered. The potential of the QFP and key technologies when QFPs are applied to a Josephson supercomputer are described. Switching speed, stability, and power dissipation of a QFP are discussed. QFP gates, circuits, and systems are next described. Then, ultra-fast clock distribution using a standing wave is explained. High-speed operation at more than 10 GHz and 10¹⁴ error-free operations per QFP have been demonstrated. Finally described is a high-density packaging scheme by three-dimensional integration, which is very important for ultra-high speed circuits because the propagation delay becomes dominant in such circuits     

Magnetic flux compression Generators

Magnetic flux compression generators offer the largest pulsed power output per unit size or weight when compared with other more conventional systems. They have found widespread use as pulsed power sources for hydrodynamics programs and high magnetic field research at national laboratories or in commercial applications, including exploration for oil and minerals and mine detection. Also, due to their nature as a true one-time-use device with superior energy density, a large portion of applications is defense related. A variety of basic magnetic flux compression generator designs have been developed and tested during the past four decades. All of them rely on the explosive-driven deformation of a system of conductors having an initial, preferably large, inductance. The most successful basic design is the helical flux compression generator, which is capable of producing a high-energy output into large impedance loads, just as it is needed for a practical pulsed power source. This paper will review the advances and state of the art of primarily helical magnetic flux compression generators mainly developed as pulsed power sources and will offer new insights gained as a result of a recently completed five-year AFOSR/DoD Multidisciplinary University Research Initiative program that studied the basic physics and engineering aspects of helical flux compression generators.     

Synchronous flux quantizing analog-to-digital-converter

An analog-to-digital-converter (ADC) based on the counting of single magnetic flux quanta has been fabricated and tested. The ADC incorporated a new synchronizing element between the flux quantizer and binary counters, making the digital output data synchronous with the system clock. This is the first demonstration of a flux quantizer, synchronizer, and counter operating together to form a completely synchronous ADC     

The flux shuttle—A Josephson junction shift register employing single flux quanta

A shift register is described which employs as information bits the flux quantum vortices occurring in Josephson junctions of extended dimensions. The positions of the vortices can be controlled and manipulated by an appropriately designed circuit geometry and by application of currents and magnetic fields. The time required for switching of the position of a vortex can approach the period of the Josephson plasma oscillation (∼10 ps) and the intrinsic energy dissipation is typically ≲ 10^-18J/shift.     

树脂芯助焊剂性能研究

树脂芯助焊剂性能对焊接质量有重要影响,为了解影响其性能的因素,研究了溶剂、活化剂及表面活性剂等的种类和配比对助焊剂性能的影响。结果表明,使用复合溶剂,按w(胺盐)为16.1%,w(有机酸)为2.0%,w(表面活性剂)为0.5%可配制成综合性能优良的助焊剂,其扩展率为80%,w(卤素)为0.07。     

Magnetic flux diffusion through HTS shields

Slow field leakage in a polycrystalline superconducting cupshield placed in an external axial field (H_ext) much weaker than H _C1 shows a diffusive time dependence with a time scale of 10 ² s. As the field strength increases but is still less than H _C1, a logarithmic time dependence of 10² s time scale is observed. It is shown that this logarithmic time dependence is a result of flux line diffusion between superconducting grains rather than fluxoid avalanches or flux bundle creep     

Single flux quantum one-decimal-digit RNS adder

Residue number system (RNS) arithmetic has a promising role for fault-tolerant high throughput superconducting single flux quantum (SFQ) circuits for digital signal processing (DSP) applications. We have designed one of the basic computational blocks used in DSP circuits, one-decimal-digit RNS adder. A new design for its main component, the single-modulus adder, has been developed. It combines simple and robust RSFQ elementary cells, both combinational and sequential. The central units are a circular shift register, a code converter, and the clock control circuitry. Our mod5 adder employs 195 Josephson junctions, consumes 50 μW of power, and occupies an area of less than 2 mm². Chips were fabricated at HYPRES, Inc. using 1 kA/cm² low-T_c Niobium technology. The mod5 adder was successfully tested at low speed, and gave experimental bias margins of ±26%.     

无VOC免清洗助焊剂焊后残留物的可靠性评价

为了研究焊后残留物的腐蚀性以及可能对PCB的电气绝缘性能造成的影响,通过表面绝缘电阻(Rs)试验和电化学迁移试验评价了三种不同固体含量的无VOC(挥发性有机物)免清洗助焊剂焊后残留物的可靠性。结果表明,使用w(固体含量)为3.6%的助焊剂,湿热试验后试件的Rs大幅下降,并且PCB表面腐蚀严重;而w(固体含量)为2.3%的助焊剂,则试件具有较高的Rs(6.4×109Ω),并且对PCB腐蚀性小。使用放大30倍的显微镜观察电化学迁移测试后的试件,均没有发现枝晶。