Probing solar and stellar interior dynamics and dynamo

Solar and stellar activity is a result of complex interaction between magnetic field, turbulent convection and differential rotation in a star’s interior. Magnetic field is believed to be generated by a dynamo process in the convection zone. It emerges on the surface forming sunspots and starspots. Localization of the magnetic spots and their evolution with the activity cycle is determined by large-scale interior flows. Thus, the internal dynamics of the Sun and other stars hold the key to understanding the dynamo mechanism and activity cycles. Recently, significant progress has been made for modeling magnetohydrodynamics of the stellar interiors and probing the internal rotation and large-scale dynamics of the Sun by helioseismology. Also, asteroseismology is beginning to probe interiors of distant stars. I review key achievements and challenges in our quest to understand the basic mechanisms of solar and stellar activity.     

重复锁定与释放功能机构研究状况及关键技术分析

综述了国内外锁定与释放功能机构的研究现状和发展状况, 并分析了各类型的锁定与释放功能机构及其锁定形式(包括节点类型与锁定方式). 着重分析了重复锁定与释放功能机构的关键技术, 包括设计影响要素、驱动、传动方式及执行机构特征, 为后续的方案设计和分析提供了依据.      

计量测试与航天科技

随着科学技术的发展,计量测试技术已渗透到国民经济的各个领域,从科研生产到贸易结算、从医疗卫生到人身安全、从环境保护到衣食住行.可以形象地说没有计量,人们就如同"盲人"一样生活在一片漆黑世界里.航天作为高科技产业,对计量更有着很强的依赖性.无论是火箭还是导弹,无论是卫星还是飞船,计量工作作为研制生产不可分割的一部分,贯穿于设计、加工、总装、测试和发射的全过程,并为评定航天产品的综合水平提供权威的依据.未来航天领域新工艺、新材料、新器件的应用,载人飞行技术的发展,航天测控、发射技术的提高,都对计量测试技术提出更高的要求.回顾国外航天大国航天事业的发展,计量在保证产品质量方面发挥了不可低估的作用.我国的航天事业正处在一个新的发展阶段."科技要发展,计量须先行".计量工作应抓住机遇,以型号需求为牵引,扎扎实实地为型号服务,为我国航天事业的发展贡献更大力量.     

太阳跟踪定位技术及其应用研究

太阳跟踪定位技术广泛应用于能源、气象和航天等领域,系统全面地对相关方法进行分类和阐述,并对多孔复用、太阳光纤导入等较新应用进行了分析,最后总结了该领域内相关技术发展的瓶颈问题,展望了未来的研究方向.     

CCSDS SCPS网络层与传输层协议分析与仿真验证

空间数据系统咨询委员会(CCSDS)针对空间通信的特点制定了空间通信协议标准SCPS(Space Communications Protocal Specification)。文章从CCSDS标准在中国空间技术的实际应用出发,对CCSDS SCPS协议中网络层协议(NP)和传输层协议(TP)进行研究,分析其特点和适用性,并与TCP/IP协议进行对比,最后设计演示验证系统对所提方案进行验证并得出结论:在空间通信环境下,采用SCPS协议后的性能优于采用TCP/IP协议。     

Combining GPS and GLONASS for time and frequency transfer

Geodetic time and frequency transfer (TFT) consists in a comprehensive modeling of code and carrier phase observations from Global Navigation Satellite System (GNSS) in order to determine the synchronization errors between two remote clocks connected to GNSS receivers. Using either common view (CV), or Precise Point Positioning (PPP), current GNSS time transfer uses only GPS measurements. This study combines GPS and GLONASS observations in geodetic TFT in order to determine the added value of the GLONASS data in the results. Using the software Atomium, we demonstrate on one hand that using both constellations improves the solution for both CV and PPP results when analysing short data batches. In that case, there are not enough GPS code data to calibrate the solution, and additional GLONASS code data allows us to retrieve a correct absolute value for the solution. On the other hand, the CV results of frequency transfer are not significantly affected by adding GLONASS data, while in PPP the combination with GLONASS modifies the frequency transfer results, and in particular the daily frequency offset, with maximum differences of 150 ps between the TFT solutions obtained with GPS-only or GPS + GLONASS.     

Operation and Application of A, B Satellites for Environment and Disaster Monitoring and Forecasting

Environment and disaster monitoring and forecasting small satellite constellation A and B satellites (HJ-1-A, B) are called "environment and disaster reduction satellites A and B' for short. The constellation adopts a 10:30 LT sun-synchronous circular orbit, with orbit altitude of 649 km. HJ-1-A and HJ-1-B are distributed with a phase difference of 180o in the same orbital plane, so as to enhance the time resolution of earth observation. The satellites have orbit maintenance capability, the lifetime is 3 years. Both satellites adopt CAST968 platforms. Two wide-coverage multispectral CCD cameras with resolution 30 m and width 700 km, a super-spectral imager with resolution 100 m and width 50 km as well as a data transmission subsystem of 120 Mbit/s are deployed on HJ-1-A, which also carries Ka communication testing equipment of Thailand. HJ-1-B has two wide-coverage multispectral CCD cameras (the same as satellite A), one infrared camera with resolution 150 m and width 720 km and a data transmission subsystem of 60 Mbit/s. The coverage period of the wide-coverage multispectral CCD camera is 48 hours. The revisit period of super-spectral imager is 96 hours and the coverage period of infrared camera is 96 hours.      

可靠性维修性保障性效能模型研究

分析了系统效能的定义及其影响因素,提出了可靠性维修性保障性效能的概念,定义了进行可靠性维修性保障性综合设计分析的一个新的参数ＲＭＳ效能ＥＲＭＳ,推导了在执行任务期间可修复和不可修复２类典型系统的ＥＲＭＳ表达式,给出了利用参数ＥＲＭＳ进行可靠性维修性保障性综合设计分析的步骤．     

飞行器雷达隐身测试评估技术及发展

武器装备全面隐身化,隐身性能指标成为装备最重要的战技指标之一.隐身测试评估是实现装备隐身性能的关键指标和不可缺少的重要环节,涉及隐身装备从方案设计验证、研制方案筛选、部件和整机隐身效果评估、使用维护检定等全生命周期.综述了飞行器雷达隐身性能试验测试体系和测试评估方法,介绍了国内外典型的测试场及测量技术进展,详细分析了低散射诊断实验测试技术的最新成果,展望了飞行器隐身电磁特性测试技术未来发展趋势.      

神舟八号飞船交会对接制导、导航与控制系统及其飞行结果评价

介绍神舟八号飞船交会对接制导、导航与控制系统的组成和工作原理,交会对接任务阶段划分,系统实现需关注的问题,以及神舟八号飞船与天宫一号目标飞行器首次交会对接飞行试验的结果和评价.     

Production and evolution of millisecond X-ray and radio pulsars

Observations using the Rossi X-ray Timing Explorer (RXTE) have discovered dozens of accreting neutron stars with millisecond spin periods in low-mass binary star systems. Eighteen are millisecond X-ray pulsars powered by accretion or nuclear burning or both. These stars have magnetic fields strong enough for them to become millisecond rotation-powered (radio) pulsars when accretion ceases. Few, if any, accretion- or rotation-powered pulsars have spin rates higher than 750 Hz. There is strong evidence that the spin-up of some accreting neutron stars is limited by magnetic spin-equilibrium whereas the spin-up of others is halted when accretion ends. Further study will show whether the spin rates of some accretion- or rotation-powered pulsars are or were limited by emission of gravitational radiation.     

高光谱遥感成像技术的发展与展望

地表形态和目标特性是空间对地遥感的两个重要问题.经过近40年的发展,高光谱遥感技术已取得了巨大的进展,从数据获取、处理到应用都积累了大量成果.作为涉及多学科交叉的年轻学科,高光谱遥感技术的发展经历了一个以需求为导向,在发展中又不断探索完善需求的历程.高光谱成像仪作为获取目标图谱数据的重要仪器,其发展对于整个高光谱遥感的...     

军工计量与市场营销

在军工计量行业快速发展的时代,计量已不仅仅具有国家法定性,它作为服务性行业同样具有市场竞争的社会性,因此,市场营销成为现代军工计量企业发展所需的重要学科。如何在当前形势下结合军工计量企业的实际情况,制定出具有军工计量特色的市场营销战略规划,是一个非常重要的问题。本文对现代军工计量企业的环境进行了分析,结合环境分析选择了相应的市场营销战略规划。     

可靠性维修性保障性效能模型研究

因素,提出了可靠性维修性保障性效能的概念,定义了进行可靠性维修性保障性综合设计分析的一个新的参数RMS效能E_RMS,推导了在执行任务期间可修复和不可修复2类典型系统的E_RMS表达式,给出了利用参数E_RMS进行可靠性维修性保障性综合设计分析的步骤.      

宽带双极化天线测量探头的设计与仿真

天线测量探头的性能对提升天线平面近场测量效率、最终测量结果的精度具有重要意义。针对平面近场测量的需要,应用反向四脊和差分馈电技术,设计了宽带双极化天线测量探头。对测量探头模型进行仿真,分析了带宽、方向图、隔离度和交叉极化辨识度等探头性能,确定了高隔离度、高极化纯度的宽带双极化天线测量探头的最优设计,获得了更高精度和效率的天线测量。     

Status and perspectives of indirect and direct dark matter searches

In this review article the current status of particle dark matter is addressed. We discuss the main theoretical extensions of the standard model which allow to explain dark matter in terms of a (yet undiscovered) elementary particle. We then discuss the theoretical predictions for the searches of particle dark matter: direct detection in low-background underground experiments and indirect detection of neutrinos, gamma-rays and antimatter with terrestrial and space-borne detectors. Attention will be placed also on the discussion of the uncertainties, mainly of astrophysical origin, which affect the theoretical predictions. The constraints placed by these searches on the extensions of the standard models will be briefly addressed.     

GPS信号捕获与跟踪策略确定及实现

为了检测GPS(Global Positioning System)信号,设计了码环及载波环捕获与跟踪数字系统.序贯搜索与窄间隔超前-滞后型数字延迟锁相环的采用,保证了码相位的可靠捕获与精确跟踪,四相鉴频器、叉积自动频率跟踪算法及科思塔环载波相位跟踪算法的结合,既保证了载波频率(多普勒频移)的捕获速度,又使环路能有效地跟踪频率/相位变化,获得较好的动态性能与噪声性能.控制算法及参数确定的软化实现使系统具有较好的灵活性.基于扩频相关器与数字信号处理器的数字系统验证了上述方案的正确性及有效性.      

GNSS reflectometry and remote sensing: New objectives and results

The Global Navigation Satellite System (GNSS) has been a very powerful and important contributor to all scientific questions related to precise positioning on Earth’s surface, particularly as a mature technique in geodesy and geosciences. With the development of GNSS as a satellite microwave (L-band) technique, more and wider applications and new potentials are explored and utilized. The versatile and available GNSS signals can image the Earth’s surface environments as a new, highly precise, continuous, all-weather and near-real-time remote sensing tool. The refracted signals from GNSS radio occultation satellites together with ground GNSS observations can provide the high-resolution tropospheric water vapor, temperature and pressure, tropopause parameters and ionospheric total electron content (TEC) and electron density profile as well. The GNSS reflected signals from the ocean and land surface could determine the ocean height, wind speed and wind direction of ocean surface, soil moisture, ice and snow thickness. In this paper, GNSS remote sensing applications in the atmosphere, oceans, land and hydrology are presented as well as new objectives and results discussed.     

Small-scale solar jet formation and their associated waves and instabilities

Studies on small-scale jets’ formation, propagation, evolution, and role, such as type I and II spicules, mottles, and fibrils in the lower solar atmosphere’s energetic balance, have progressed tremendously thanks to the combination of detailed observations and sophisticated mathematical modelling. This review provides a survey of the current understanding of jets, their formation in the solar lower atmosphere, and their evolution from observational, numerical, and theoretical perspectives. First, we review some results to describe the jet properties, acquired numerically, analytically and through high-spatial and temporal resolution observations. Further on, we discuss the role of hydrodynamic and magnetohydrodynamic instabilities, namely Rayleigh–Taylor and Kelvin–Helmholtz instabilities, in jet evolution and their role in the energy transport through the solar atmosphere in fully and partially ionised plasmas. Finally, we discuss several mechanisms of magnetohydrodynamic wave generation, propagation, and energy transport in the context of small-scale solar jets in detail. This review identifies several gaps in the understanding of small-scale solar jets and some misalignments between the observational studies and knowledge acquired through theoretical studies and numerical modelling. It is to be expected that these gaps will be closed with the advent of high-resolution observational instruments, such as Daniel K. Inouye Solar Telescope, Solar Orbiter, Parker Solar Probe, and Solar CubeSats for Linked Imaging Spectropolarimetry, combined with further theoretical and computational developments.