陕西省县域经济发展浅探

党的十六大提出"壮大县域经济"以来,县域经济作为社会经济一种新的发展模式已受到社会各界越来越多的关注.发展壮大县域经济,增强县城经济活力和竞争力,也是陕西省目前经济发展的重要任务之一.通过对陕西省县域经济现状的阐述,指出了存在的问题,提出了强化特色意识、环境意识、开放意识和推进"三化"进程等发展壮大陕西省县域经济的建议和措施.     

Using high-energy proton fluence to improve risk prediction for consequences of solar particle events

The potential for exposure to large solar particle events (SPEs) with high energy levels is a major concern during interplanetary transfer and extra-vehicular activities (EVAs) on the lunar and Mars surface. Previously, we have used data from the last 5 solar cycles to estimate percentiles of dose to a typical blood-forming organ (BFO) for a hypothetical astronaut in a nominally shielded spacecraft during a 120-d lunar mission. As part of this process, we made use of complete energy spectra for 34 large historical SPEs to calculate what the BFO mGy-Eq dose would have been in the above lunar scenario for each SPE. From these calculated doses, we then developed a prediction model for BFO dose based solely on an assumed value of integrated fluence above 30 MeV (Φ₃₀) for an otherwise unspecified future SPE. In this study, we reasoned that since BFO dose is determined more by protons with higher energies than by those with lower energies, more accurate BFO dose prediction models could be developed using integrated fluence above 60 (Φ₆₀) and above 100 MeV (Φ₁₀₀) as predictors instead of Φ₃₀. However to calculate the unconditional probability of a BFO dose exceeding a pre-specified limit (“BFO dose risk”), one must also take into account the distribution of the predictor (Φ_30,Φ₆₀, or Φ₁₀₀), as estimated from historical SPEs. But Φ₆₀ and Φ₁₀₀ have more variability, and less available historical information on which to estimate their distributions over many SPE occurrences, than does Φ₃₀. Therefore, when estimating BFO dose risk there is a tradeoff between increased BFO dose prediction at a given energy threshold and decreased accuracy of models for describing the distribution of that threshold over future SPEs as the threshold increases. Even when taking the second of these two factors into account, we still arrived at the conclusion that overall prediction improves as the energy level threshold increases from 30 to 60 to 100 MeV. These results can be applied to the development of approaches to improve radiation protection of astronauts and the optimization of mission planning for future space missions.     

Interstellar planetary protection

In the coming decades the detection of Earth-like extrasolar planets, either apparently lifeless or exhibiting spectral signatures of life, will encourage design studies for craft to visit them. These missions will require the elaboration of an interstellar planetary protection protocol. Given a specific dose required to sterilize microorganisms on a spacecraft, a critical mean velocity can be determined below which a craft becomes self-sterilizing. This velocity is calculated to be below velocities previously projected for interstellar missions, suggesting that an active sterilization protocol prior to launch might be required. Given uncertainties in the surface conditions of a destination extrasolar planet, particularly at microscopic scales, the potential for unknown biochemistries and biologies elsewhere, or the possible inoculation of a lifeless planet that is habitable, then both lander and orbiter interstellar missions should be completely free of all viable organisms, necessitating a planetary protection approach applied to orbiters and landers bound for star systems with unknown local conditions for habitability. I discuss the case of existing craft on interstellar trajectories – Pioneer 10, 11 and Voyager 1 and 2.     

名城文化误区与政府文化观

当前历史名城的保护和建设中,出现了不少文化误区,表现为“泛文化”、“狭文化”、“假文化”、“死文化”、“功利文化”以及文化的“泛产业化”和非特色化,等等。产生这些误区的原因不仅仅是政府利益和政绩观、发展观产生偏差,政府文化观的缺失与错位才是问题产生的根源,因此,只有培养正确的文化观和体制改革双管齐下,才能更好地保护和传承名城文化,避免借保护之名行破坏之实的行为。     

基于数字水印的多媒体教学资源版权保护的研究

针对视频、音频、电子课件等多媒体教学资源亟待解决的版权保护问题,提出一种新的基于数字水印技术的解决方案。并结合目前教学资源管理系统的结构进行实践性的探索,得出一种系统解决教学资源版权保护的技术方法。     

金属热防护系统多层隔热材料的传热分析及参数优化

采用能量平衡方程和离散坐标法近似地建立了金属热防护系统多层隔热材料的一维稳态传热的数学模型,并利用遗传算法和纤维隔热材料的有效导热系数试验数据求解传热反问题,从而得到了模型中的纤维隔热材料的辐射衰减系数、反照率和隔热屏表面辐射发射系数。最后,由实验测得了多层隔热材料的有效导热系数,验证了采用优化参数后,多层隔热材料的传热模型的正确性。     

UWB与GNSS结合的室内外一体化定位系统设计

针对电力北斗安全应用、自动驾驶导航等应用场景对室内外一体化无缝定位的迫切需求,设计了一种将UWB与GNSS结合的一体化无缝定位系统.通过将UWB标签与小型化GNSS模块集成到手持智能设备上形成一体化定位终端,服务器软件对卫导结果与超宽带定位结果进行融合,输出连续定位结果.实验结果表明,该系统可以实现人员的室内外一体化无...     

HDI三聚体和偶联剂对纸质文物加固保护的研究

用传统的高分子树脂对纸质文物进行加固保护取得了一定的效果，但由于高分子树脂的渗透、润湿性能较差，容易增加纸张光泽；会产生内应力加速纸张老化等问题。针对这个问题，本文研究了一种纸质文物加固保护的新方法，采用低分子预聚物HDI三聚体对纸张聚氨酯化，并用偶联剂KH-550协同处理。通过正交试验分析了处理工艺中各种因素对纸张拉伸干强度的影响；并通过对拉伸湿强度、光泽度的测试和酸碱加速老化、干热加速老化等试验验证了HDI三聚体和KH-550对纸质文物的加固保护作用，并用DSC和扫描电镜进行了分析。试验表明，这种处理方法在保护纸张原有质感的同时提高了纸张强度，降低了纸纤维的吸湿性，有效地减缓了纸张的老化降解。     

柔性热防护系统及相关热考核试验

柔性热防护系统为高超声速充气气动减速器的防热需求而发展,主要为大质量地球再入及未来火星的进入、下降和着陆系统的防热而研发。本文介绍了美国针对高超声速充气气动减速器已经进行和正在策划的飞行试验情况以及火星进入、下降和着陆系统对柔性热防护系统的使用热环境需求。对柔性热防护系统的基本组成进行了介绍,详细描述柔性热防护系统的相关热考核试验。     

固体火箭发动机内绝热层烧蚀分析

提出了一种固体发动机内绝热层的化学烧蚀模型。模型考虑了发生在绝热层烧蚀表面的五种化学反应。绝热展在烧蚀过程中按材料物性变化情况分为碳化层、原始材料层,中间假设为一热解面。在内绝热层烧蚀模型中建立了内绝热层表面烧蚀过程的能量和质量的平衡关系,并运用动边界热传导差分求解出绝热层内部的温度场。用该模型对一种固体发动机内绝热层的烧蚀进行了计算,其结果与发动机试验解剖测量值基本相符。