车辆追踪运行的离散模型与最优控制

对车辆追踪运行进行控制,是实现车辆安全、快捷运行的重要手段之一.将车辆追踪运行控制问题归结为“速度差”调节和标准车距跟踪的混合系统进行研究.建立了离散模型,分析了其能控性和能观性,运用最优控制理论求解其反馈控制律,给出了算法步骤.对具体算例进行了仿真实现.     

模电教学中工程观念的培养

"模拟电子线路"课程是工科本科电子信息类专业的一门重要的专业基础课程.本文以集成运放电路在压力检测中的应用为例,探讨了模拟电子线路课程教学中如何将理论联系实际、如何培养工程观念、如何将基本理论与工程应用相结合等问题.通过课程教案示例,阐述了工程观念的培养在教学实践中的具体做法.     

H.264/AVC编解码器在TMS320C6400上的优化实现

分析了基于TMS320C6400平台的H.264/AVC编码器运算量在各个部分的分布,并且将其中运算量较大的部分进行线性汇编,分析了这些部分在进行线性汇编时需要注意的技术细节,能够提高线性汇编的并行程度.     

淡竹叶多酚的提取纯化工艺优化、组分分析及体外抗氧化活性研究

目的 确定淡竹叶多酚提取纯化工艺,分析主要成分及体外抗氧化活性。方法 采用超声辅助提取淡竹叶多酚,通过响应面实验确定最佳提取条件。选取适合淡竹叶多酚纯化的大孔树脂,对纯化工艺参数进行优化。通过高效液相色谱-质谱法(high performance liquid chromatography-mass spectrometry, HPLC-MS)鉴定淡竹叶多酚的主要成分,并评价其体外抗氧化活性。结果 淡竹叶多酚的最佳提取工艺参数为:乙醇体积分数60%、超声功率500 W、料液比1:25 (g/mL)、超声时间24 min及超声温度59℃,该条件下淡竹叶多酚提取量为8.01 mg/g。淡竹叶多酚纯化工艺参数为:上样质量浓度6 mg/mL、pH 4、流速2 mL/min、解吸液为70%乙醇、解吸体积90 mL,纯化后的淡竹叶多酚纯度由12.86%提高到76.18%。通过HPLC-MS鉴定出16种酚类成分,且纯化后多酚有较高的抗氧化活性。结论 本研究得到了淡竹叶多酚提取纯化工艺,得到的多酚纯化物有明显的抗氧化活性。     

Comparison of modified injection molding and conventional machining in biodegradable behavior of perforated cannulated magnesium hip stents

In this study,perforated cannulated magnesium(Mg)hip stents were fabricated via modified Mg injection molding and conventional machining,respectively.Additionally,the stent canal was filled with paraffin to simulate injection of biomaterials.The microstructure,mechanical performance,corrosion behavior,and biocompatibility were comparably studied.Scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)showed higher affinity of interstitial element such as oxygen and carbon as consequences of routine molding process.After immersion in SBF,machining stents showed reduced degradation rate and increased deposition of calcium phosphate compared to molding stents.Corrosion resistance was improved via paraffin-filling.Consistently,the hemolysis and in vitro osteoblast cell culture models showed favourable biocompatibility in machining stents compared to molding ones,which was improved by paraffin-filling treatment as well.These results implied that the feasibility of the prepared machining stents as the potential in vivo orthopaedic application where slower degradation is required,which could be enhanced by designing canal-filling injection of biomaterials as well.     

Photorhabdus luminescens TccC3 Toxin Targets the Dynamic Population of F-Actin and Impairs Cell Cortex Integrity

Due to its essential role in cellular processes, actin is a common target for bacterial toxins. One such toxin, TccC3, is an effector domain of the ABC-toxin produced by entomopathogenic bacteria of Photorhabdus spp. Unlike other actin-targeting toxins, TccC3 uniquely ADP-ribosylates actin at Thr-148, resulting in the formation of actin aggregates and inhibition of phagocytosis. It has been shown that the fully modified F-actin is resistant to depolymerization by cofilin and gelsolin, but their effects on partially modified actin were not explored. We found that only F-actin unprotected by tropomyosin is the physiological TccC3 substrate. Yet, ADP-ribosylated G-actin can be produced upon cofilin-accelerated F-actin depolymerization, which was only mildly inhibited in partially modified actin. The affinity of TccC3-ADP-ribosylated G-actin for profilin and thymosin-β4 was weakened moderately but sufficiently to potentiate spontaneous polymerization in their presence. Interestingly, the Arp2/3-mediated nucleation was also potentiated by T148-ADP-ribosylation. Notably, even partially modified actin showed reduced bundling by plastins and α-actinin. In agreement with the role of these and other tandem calponin-homology domain actin organizers in the assembly of the cortical actin network, TccC3 induced intense membrane blebbing in cultured cells. Overall, our data suggest that TccC3 imposes a complex action on the cytoskeleton by affecting F-actin nucleation, recycling, and interaction with actin-binding proteins involved in the integration of actin filaments with each other and cellular elements.     

西北电网水电参与市场化运营若干问题的研究

随着我国市场化的推进,水电正酝酿逐步参与到电力市场化运营中去。水电参与电力市场竞争,有利于市场的有效性,可以在更大范围内利用市场机制优化资源配置,健全电价机制,优化水能源的利用,更好地为经济社会的协调发展服务。在详细分析西北电网水电参与市场化运营问题的基础上,针对水电的特有规律,提出了相应的建议。     

海豹油n-3PUFA富集过程中品质及挥发性物质的变化

以海豹油乙酯为原料,采用尿包法和分子蒸馏法对其中的n-3PUFA进行富集,通过理化分析、气相色谱(GC)及顶空固相微萃取-气-质谱联用(HS-SPME-GC-MS)等技术研究富集过程中样品品质、脂肪酸组成和挥发性物质的变化.结果表明:尿包法和分子蒸馏法可以显著提高样品的皂化值和碘值,对酸价和过氧化物值影响不大.尿包法可...     

SQLMVED:基于多变体执行的SQL注入运行时防御系统

SQL解析过程中利用随机化进行SQL注入攻击(SQLIA)防御的有效性是建立在攻击者不了解当前系统采用的具体随机化方法的基础上,因此,攻击者一旦掌握了当前系统的随机化形式,便能够实施有效的SQLIA.为了解决该问题,基于多变体执行设计出一种SQL注入运行时防御系统,多变体间采用互不相同的随机化方法,攻击者注入的非法SQ...     

由土壤水分特征曲线反推土壤孔隙分形维数

利用分形几何理论,可在水分特征曲线与土壤结构分维之间建立一定的函数关系式。利用这些函数关系式与Campbell经验公式具有相同或相似的幂定律形式的特点,由土壤水分特征曲线反推土壤孔隙分形维数,这不仅可以揭示Campbell经验公式与土壤孔隙结构之间的内在联系,还可为建立土壤非饱和水力参数的分形模型提供理论依据。