The population of massive stars in R136 from HST/FOC UV observations

New ultraviolet (1300 A, 3400 A),HST FOC observations have been used to derive the UV color-magnitude diagram (CMD) of R136, with the main scientific goal of studying the upper end of the stellar mass function at ultraviolet wavelengths where the color degeneracy encountered in visual CMDs is less severe. The CMD has been compared to a set of theoretical isochrones, which have been computed using the latest generation of evolutionary models and model atmospheres for early type stars. Wolf-Rayet stars are included. Comparison of theTheoretical andobserved CMD suggests that there are no stars brighter than M₁₃₀–11. We use the observed main sequence turn-off and the known spectroscopic properties of the stellar population to derive constraints on the most probable age of R136. The presence of WNL stars and the lack of red supergiants suggests a most likely age of 3±1 Myr. A theoretical isochrone of 3±1 Myr is consistent with the observed stellar content of R136 if the most massive stars have initial masses around 50 M.Bases on Observations with the NASA/ESA Hubble Space Telescope, obtained at the STScI, which is operated by AURA, Inc., under NASA contract NAS5-26555.Astrophysics Division, Space Science Department, ESA     

多功能CAN节点电路的设计及其应用

介绍一种多功能CAN节点的电路结构及在工业中频感应加热设备控制现场总线中的应用。     

金翼医院管理信息系统简介及推广中遇到的问题与思考

简要介绍了金翼医院管理信息系统 (JinYiHospitalManagementInformationSystem)功能及在推广应用过程中遇到的问题 ,对如何解决这些问题 ,提出了一些建议 ,从而使HMIS得到进一步推广应用     

Magnetar spectra and twisted magnetospheres

The huge potential drop between the footpoints of the closed field lines in the twisted magnetospheres of magnetars may accelerate electrons up to very high energies, γ ? 10⁶. On the other hand, the comparison between the observed spectra of magnetars and spectra obtained by accurate theoretical models seems to favor of a picture in which the magnetosphere is filled by “slow” electrons (v ? 0.8c), rather than by ultra-relativistic particles.     

Modeling the broadband persistent emission of magnetars

In this paper, we discuss our first attempts to model the broadband persistent emission of magnetars within a self-consistent, physical scenario. We present the predictions of a synthetic model that we calculated with a new Monte Carlo 3D radiative code. The basic idea is that soft thermal photons (e.g. emitted by the star surface) can experience resonant cyclotron upscattering by a population of relativistic electrons treated in the twisted magnetosphere. Our code is specifically tailored to work in the ultra-magnetized regime; polarization and QED effects are consistently accounted for, as well different configurations for the magnetosphere. We discuss the predicted spectral properties in the 0.1–1000 keV range, the polarization properties, and we present the model application to a sample of magnetars soft X-ray spectra.     

基于深度学习的组合体航天器模型预测控制

利用模型预测算法先预测控制结果后控制的类人行为特点，借助深度学习在多参数寻优上的优势，提出了一种基于卷积神经网络的模型预测控制算法，满足航天工程低硬件需求，实现组合航天器多场景下姿态控制律的重构。该算法首先利用模型预测控制将组合航天器从初始状态控制到预期状态，然后将控制过程中状态量用于3层3核卷积神经网络的训练，训练完成后，用该卷积神经网络代替模型预测对组合航天器进行控制，从而降低计算资源需求。仿真校验表明：该算法可预测5个控制周期内的控制参数，相比传统模型预测算法所需硬件计算时间降低约5倍，在一般硬件环境下30 s内即可完成各场景下的组合航天器姿态控制，控制精度在10 -4 量级。     

Experimental and theoretical burning of solid rocket propellants near the pressure deflagration limit

Burning of composite solid rocket propellants near the pressure deflagration limit (PDL) was studied experimentally in two different test chambers. The propellant tested was a nonmetallized ammonium perchlorate-based composite propellant (AP 84/CTPB 16). Measurements were taken of the regression rate, oscillations frequency and flame luminosity. Self-sustained oscillations were detected near the PDL that matched reasonably well the predictions of the analytical nonlinear stability theory and of the numerically solved nonlinear mathematical model. Both experimental and numerical results show the burning rate oscillations near the PDL due to statically unstable burning, that is the only combustion regime possible below a certain pressure. When pressure is further reduced the amplitude of the oscillations increases and their frequency decreases, until extinction follows abruptly below a pressure that corresponds to the PDL.     

The comprehensive aerospace index (CASI): Tracking the economic performance of the aerospace industry

In this paper, we described the Comprehensive AeroSpace Index (CASI), a financial index aimed at representing the economic performance of the aerospace industry. CASI is build upon a data set of approximately 20 years of daily close prices set, from January 1987 to June 2007, from a comprehensive sample of leading aerospace-related companies with stocks negotiated on the New York Exchange (NYSE) and on the over-the-counter (OTC) markets. We also introduced the sub-indices CASI-AERO, for aeronautical segment, and CASI-SAT, for satellite segment, and considered the relation between them. These three indices are compared to others aerospace indices and to more traditional general financial indices like DJIA, S&P500 and Nasdaq. Our results have shown that the CASI is an index that describes very well the aerospace sector behavior, since it is able to reflect the aeronautical segment comportment as well as the satellite one. Therefore, in this sense, it can be considered as a representative index of the aerospace sector. Moreover, the creation of two sub-indices, the CASI-AERO and the CASI-SAT, allows to elucidate capital movements within the aerospace sector, particularly those of speculative nature, like the dot.com bubble and crash of 1998–2001.     

Fixed membrane wings for micro air vehicles: Experimental characterization,numerical modeling,and tailoring

Fixed wing micro air vehicles (wingspan between 10 and 15 cm) are aerodynamically challenging due to the low Reynolds number regime (10⁴–10⁵) they operate in. The low aspect ratio wings (typically used to maximize area under a size constraint) promote strong tip vortices, and are susceptible to rolling instabilities. Wind gusts can be of the same order of magnitude as the flight speed (10–15 m/s). Standard control surfaces on an empennage must be eliminated for size considerations and drag reduction, and the range of stable center of gravity locations is only a few millimeters long. Membrane aeroelasticity has been identified as a tenable method to alleviate these issues: flexible wing structures with geometric twist (adaptive washout for gust rejection, delayed stall) and aerodynamic twist (adaptive inflation for high lift, larger stability margins) are both considered here. Recent investigations in static aeroelastic characterization, including flight loads, wing deformation, flow structures, aeroelastic-tailoring studies through laminate orientation, as well as unconventional techniques based on membrane pre-tension, are reviewed. Multi-objective optimization aimed at improving lift, drag, and pitching moment considerations is also discussed.     

The Magellan project

Magellan is one of the future space projects being studied by the European Space Agency. The aim is to provide high resolution (λ/Δλ ≥ 2.5 × 10⁴) spectra in the far and extreme UV (between 500 and 1550 Å) of faint galactic and extragalactic objects (V ≤ 16^m). The instrument consists of a mechanical collimator, a concave holographic grating and a bidimensional photon-counting detector. A low resolution mode (λ/Δλ ≥ 10³) will provide spectra of objects as faint as 18^m.5. Magellan is planned as an observatory, operated in real time, and allowing interaction with the observer.