卷积型积分微分方程解的稳定性定理

本文研究卷积型积分微分方程（１）和（２），建立了方程（１）和（２）的零解渐近稳定的若干充分性准则。     

Magnetic order close to superconductivity in the iron-based layered LaO1-xFxFeAs systems

Following the discovery of long-range antiferromagnetic order in the parent compounds of high-transition-temperature (high-T(c)) copper oxides, there have been efforts to understand the role of magnetism in the superconductivity that occurs when mobile 'electrons' or 'holes' are doped into the antiferromagnetic parent compounds. Superconductivity in the newly discovered rare-earth iron-based oxide systems ROFeAs (R, rare-earth metal) also arises from either electron or hole doping of their non-superconducting parent compounds. The parent material LaOFeAs is metallic but shows anomalies near 150 K in both resistivity and d.c. magnetic susceptibility. Although optical conductivity and theoretical calculations suggest that LaOFeAs exhibits a spin-density-wave (SDW) instability that is suppressed by doping with electrons to induce superconductivity, there has been no direct evidence of SDW order. Here we report neutron-scattering experiments that demonstrate that LaOFeAs undergoes an abrupt structural distortion below 155 K, changing the symmetry from tetragonal (space group P4/nmm) to monoclinic (space group P112/n) at low temperatures, and then, at approximately 137 K, develops long-range SDW-type antiferromagnetic order with a small moment but simple magnetic structure. Doping the system with fluorine suppresses both the magnetic order and the structural distortion in favour of superconductivity. Therefore, like high-T(c) copper oxides, the superconducting regime in these iron-based materials occurs in close proximity to a long-range-ordered antiferromagnetic ground state.     

血管成形术和Stent放置术放射治疗后动脉损伤的治疗

用于评价经皮穿刺血管成形术和Ｓｔｅｎｔ在放疗后所致动脉疾病的治疗,及靶血管内Ｓｔｅｎｔ的长期支撑开放作用。资料和方法：１４例患者,因为放疗所致１８处动脉性病变,而给予血管成形术治疗。１３个Ｓｔｅｎｔ放置于８个患者,分别治疗血管闭塞３例,内膜撕裂１例,动脉瘤１例,残存狭窄２例,多发狭窄１例,球囊成形术后再发狭窄１例。所有病例均用ＣＴ扫描和／或多普勒超声检查,观察Ｓｔｅｎｔ及其靶血管内和Ｓｔｅｎｔ内的血流情况。结果：血管成形术成功治疗１４例病人,８例患者在动脉病变处放置Ｓｔｅｎｔ。１１例动脉病基本消失,追踪２年（８月～５年）,临床症状完全解除,３例临床症改善。１１例患者接受了１或２次血管成形术。１例患者重复承受了４次血管成形术,并放置３个Ｓｔｅｎｔ,２个Ｓｔｅｎｔ放在两髂总动脉和腹主动脉,１个Ｓｔｅｎｔ放在腹腔动脉。另１位重复４次血管成形术的患者,在肠系膜上动脉放了２个Ｓｔｅｎｔ。最后１例,因为血管成形术后内膜撕裂和血管闭塞,而放置了１个Ｓｔｅｎｔ,经５年随防,其动脉病变为临床治愈。结论：单一的血管成形术或者多技术综合运用,可有效治疗放疗所致的动脉性病变,应考虑其为动脉损伤性病变的首选治疗     

基于线性回归分析的快速搜索聚类中心算法

针对一种可快速搜索和寻找到聚类密度峰值点聚类算法的缺陷,利用线性回归与残差分析的方法进行改进,可自动、快速地确定聚类中心且优化样本点密度值。算法利用样本点的近邻信息重新度量点的密度值,提高聚类中心点位置稳定性;利用一元线性回归与残差分析,快速、自动地选出聚类中心点,去除了人为选择的主观性。通过理论分析以及在人工数据集和真实数据集的对比实验表明,提出的基于线性回归分析的快速搜索聚类中心算法能够克服原有算法的缺陷,并且在聚类效果和计算时间上优于原有算法、基于密度的带有噪声的空间聚类算法(density based spatial clustering of applications with noise, DBSCAN)以及K-means算法。     

Infinitesimal dividing modeling method for dual suppliers inventory model with random lead times

As one of the basic inventory cost models, the (Q, r) inventory cost model of dual suppliers with random procurement lead time is mostly formulated by using the concepts of "effective lead time" and "lead time demand", which may lead to an imprecise inventory cost. Through the real-time statistic of the inventory quantities, this paper considers the precise (Q, r) inventory cost model of dual supplier procurement by using an infinitesimal dividing method. The traditional modeling method of the inventory cost for dual supplier procurement includes complex procedures. To reduce the complexity effectively, the presented method investigates the statistics properties in real-time of the inventory quantities with the application of the infinitesimal dividing method. It is proved that the optimal holding and shortage costs of dual supplier procurement are less than those of single supplier procurement respectively. With the assumption that both suppliers have the same distribution of lead times, the convexity of the cost function per unit time is proved. So the optimal solution can be easily obtained by applying the classical convex optimization methods. The numerical examples are given to verify the main conclusions.     

基于模糊滑模控制策略的电动助力转向系统的回正控制

参考整车二自由度模型,建立汽车在低速和中高速回正工况下的电动助力转向系统动力学模型.考虑到系统的复杂性、模型参数的不确定性和外界扰动,结合两种具有良好鲁棒性的控制策略(模糊控制策略和滑模控制策略)各自的优点,设计了用于改善电动助力转向系统回正特性的模糊滑模控制器.仿真结果表明,汽车低速和中高速时的回正特性都得到了改善,很好地解决了汽车回正过程中的回正不足和回正超调,验证了模糊滑模控制算法的有效性.     

松藻矿区石壕井田东翼Ⅱ区煤层涌水量预测

利用涌水量预测方法,分析了石壕煤矿技改扩能后,矿井设计生产能力由90万t／a,提高到180万t/a的生产能力。利用现有生产水平涌水量的参考资料,对开采东翼Ⅱ区煤层-200标高水平开采提高到矿井生产能力180万t／a的涌水量预测。可供类似矿井涌水量预测提供参考。     

基于熵权的灰色关联辐射源威胁评估

辐射源威胁评估可为后期干扰资源配置及任务分配提供依据,是机载自卫电子对抗的重要研究课题。针对评估指标少、不全面的问题,从影响威胁等级的距离估计指标、分辨力估计指标、概率估计指标和平台指标出发建立辐射源威胁评估体系,通过参数集输入计算出各指标值;然后运用基于熵权的灰色关联方法,通过熵权法对权重客观赋值,结合最优、最劣关联度,得到灰色关联相对贴近度;最后,对贴近度排序,评判威胁等级。仿真表明,定量计算与定性分析结果的一致说明了算法的有效性;与选取的2种改进算法进行威胁排序与运算时间的对比,其结果的一致和运算时间上的优势说明了算法的可行性和时效性。     

体裁与时空关系论——巴赫金《小说的时间形式和时空体形式》中的历史类型学思想

《小说的时间形式和时空体形式》是一篇重要但长期被忽略的比较文学理论文献。通过汲取维谢洛夫斯基的历史诗学资源，巴赫金将历史方法和美学沉思结合起来，从而在历史类型学的方法论上取得突破，并在此基础上对西方小说的历史类型作了清晰的分类和描述。     

基于DPSIR模型的山东油气产业可持续发展因素分析

运用DPSIR模型,以指标驱动力、压力、状态、影响进行细化,分析各指标下山东省油气产业表现出的特有状态,结合状态的呈现原因和发展结果进行宏观分析,明确了状态下存在的主要问题以及面临的主要危机,最后,从战略战术层面提出了山东油气可持续发展的具体措施.