亚轨道飞行器任务中止再入轨迹优化设计

针对亚轨道飞行器上升段由于动力故障任务中止时再入返回的问题,考虑飞行模型简化和故障后的燃料处理方案,通过遗传算法优化设计最优返回轨迹,优化时选取经向飞行航程最远作为性能指标,并采用遗传算法,解决用于再入轨迹优化所涉及的关键问题,并进行仿真。仿真结果表明,方法不但满足飞行器返回过程中加热率、过载、动压约束以及终端状态约束,能够通过飞行航程最远消耗飞行器能量从而安全着陆,而且可以较快地搜索到全局最优解,能够用于亚轨道飞行器故障再入轨迹的优化设计。     

亚轨道飞行器进场着陆段控制方法研究

研究轨道系统在常用的飞行控制方法的基础上,进一步分析了亚轨道飞行器着陆段飞行的特点,为实现精确着陆,将进场着陆段分为纵向和侧向两个相互独立的运动来分别予以分析,并以内外回路的设计方法给出相应的控制规律,以X-34为模型,制定相应的控制策略,保证着陆时飞行器精确跟踪轨迹线。仿真结果证实方法可以对亚轨道飞行器进场着陆段进行有效的跟踪控制。大量仿真试验表明控制规律对于进场着陆是切实可行的。     

SRLV再入段制导的快速原型实现

为解决传统开发模式周期长、成本高、效率低,无法满足亚轨道可重复使用运载器制导系统预先研究的要求的问题,该文提出了一种面向TI DSP的制导系统快速原型实现方法。利用此方法建立了基于衍化的加速度制导方法的系统原型,进行了大量实时仿真,改进了制导率,大大加速了亚轨道可重复使用运载器制导系统的开发过程,缩短了开发周期,降低了研究成本,提高了研究效率。目前该快速原型开发平台正在进一步完善,以期应用到工程设计中。     

亚轨道飞行器推力常值损失下应急上升段飞行程序设计

针对亚轨道飞行器(SRLV)应急返回任务,在分析不同故障时段所具有的飞行特点的基础上,提出一种发动机推力常值损失下应急大气上升段飞行程序设计方法.该方法采用随动压变化的正攻角设计方案用于故障后飞行程序设计,使得不同故障时刻SRLV均能够安全到达低动压环境.仿真结果表明,不同故障时刻,该方法均能够在满足弯矩约束、攻角限制的情况下使得故障飞行器安全到达预定高度,为后续应急返回机动飞行提供了有利的飞行条件.     

Species-Specific Humoral Immune Responses in Sheep and Goats upon Small Ruminant Lentivirus Infections Inversely Correlate with Protection against Virus Replication and Pathological Lesions

Maedi-Visna-like genotype A strains and Caprine arthritis encephaltis-like genotype B strains are small ruminant lentiviruses (SRLV) which, for incompletely understood reasons, appear to be more virulent in sheep and goats, respectively. A 9-month in vivo infection experiment using Belgian genotype A and B SRLV strains showed that almost all homologous (genotype A in sheep; genotype B in goats) and heterologous (genotype A in goats; genotype B in sheep) intratracheal inoculations resulted in productive infection. No differences in viremia and time to seroconversion were observed between homologous and heterologous infections. Higher viral loads and more severe lesions in the mammary gland and lung were however detected at 9 months post homologous compared to heterologous infection which coincided with strongly increased IFN-γ mRNA expression levels upon homologous infection. Pepscan analysis revealed a strong antibody response against immune-dominant regions of the capsid and surface proteins upon homologous infection, which was absent after heterologous infection. These results inversely correlated with protection against virus replication in target organs and observed histopathological lesions, and thus require an in-depth evaluation of a potential role of antibody dependent enhancement in SRLV infection. Finally, no horizontal intra- and cross-species SRLV transmission to contact animals was detected.