抗生素调节的单种群chemostat模型研究

构建并分构了抗生素调节的单种群chemosta模型 ,得到了依赖于抗生素输入浓度的微生物种群绝灭和一致持续生存的充分条件 .     

一类无穷下三角矩阵的代数性质

修正了 [4,5]中的 Jabotinsky矩阵,得到并证明了一类无穷下三角矩阵T（f）的一些性质,最后,导出了一些与导数相关的反演关系和组合恒等式.     

双折射滤光片的色散特性研究

研究了由理想线偏振片和单轴双折射晶体波片组成的双折射滤光片倾斜放置时的二阶色散和 三阶色散特性，包括波片厚度、光线入射角和光轴旋转角的变化对二阶和三阶色散的影响. 还给出了双折射滤光片的群延迟表达式，并就色散特性与GT干涉仪进行了详细比较. 关键词： 双折射滤光片 群延迟 二阶色散 三阶色散     

Naphthyl azomesogens with lateral chloro groups

A homologous series of azomesogens, 2″-[4-(4′-n-alkoxybenzoyloxy)-2-chlorophenylazo] naphthalenes, with lateral chloro groups was synthesised. All the homologues synthesized exhibit enantiotropic nematic mesophase. The mesomorphic properties of the present series are compared with other structurally related series to evaluate the effect of lateral chloro group and its position on mesomorphism This paper was presented at the 10th National Conference on Liquid Crystals held at Bangalore, India during 9–11 October 2003.     

A classical no-interaction theorem for bosonic strings and its quantum significance

We show that, in dimensions equal or greater than three, classical strings do not join or split. This is part of a no-interaction theorem that is also proved. The quantum theory is considered.     

On the onset of separation in turbulent boundary layer flow over two-dimensional humps of various size

Summary The available laboratory data of turbulent boundary layer flow over two-dimensional obstacles have been examined in order to identify the parameters (such as the aspect ratio or the surface roughness) driving the onset of separation. A comparison with some linearized models suitable for atmospheric applications is also made. It results that i) the model response can be highly sensitive to the detailed shape of the obstacle; ii) the ratio between obstacle length and boundary layer thickness is relevant in determining the pressure perturbation near the surface; iii) the surface shear stress is poorly described in most cases and in particular in the obstacle wake.

---

Riassunto I dati di laboratorio disponibili, relativi a strati limite turbolenti su ostacoli bidimensionali, sono stati esaminati al fine di identificare i parametri guida della separazione (quali la pendenza o la rugosità della superficie). Inoltre è stato fatto un confronto con i risultati di alcuni modelli linearizzati adatti per applicazioni atmosferiche. Ne risulta che i) la risposta del modello è molto sensibile alla forma dettagliata dell’ostacolo; ii) il rapporto fra la lunghezza dell’ostacolo e lo spessore dello strato limite turbolento incidente è importante nel determinare la perturbazione della pressione vicino alla superficie; iii) lo ?shear stress? superficiale non è riprodotto con accuratezza nella maggioranza dei casi, in particolare nella scia dell’ostacolo.

---

Резюме Анализируются имеющиеся лабораторные данные по турбулентному течению в пограничном слое над двумерными препятствиями, чтобы идентифицировать параметры (такие как аспектное отношение или шероховатость поверхности), определяющие возникновение отрыва. Проводится сравнение с некоторыми линеаризованными моделями, удобными для атмосферных приложений. Получены следующие результаты: 1) модельный отклик может быть очень чувствительным к детальной форме препятствия; 2) отношение между длиной препятствия и толщиной поверхностного слоя является существенным при определении возмущения давления вблизи поверхности; 3) напряжение поверхностного сдвига плохо описывается в большинстве случаев и, в частности, в спутной струе.

     

Development of a quantitative FI-MS technique for the characterization of high- and nonboiling saturated hydrocarbon mixtures

Summary Using a saturated non-boiling hydrocarbon mixture, the influence of two parameters on the results of field ionization mass spectrometry (FI-MS) measurements was studied: (a) the potential difference between the FI emitter and the counterelectrode; (b) the emitter temperature.Variation of the potential difference had only a minor effect on the average molecular mass measured and had no evident effect on the relative ring number distribution in the sample. In contrast, when the emitter temperature was increased, higher average molecular masses were recorded. Moreover, the average molecular masses shifted to higher ring numbers. In order to control the relationship between the described influences during mixture analysis, measuring instructions have been developed that enable the quantitative analysis of unknown saturated samples. However, average molecular mass of the mixture must be known.

---

Entwicklung einer quantitativen FI-MS-Methode zur Charakterisierung von gesättigten hoch- und nichtsiedenden Kohlenwasserstoffgemischen