Load Balancing with Availability Checker and Load Reporters (LB-ACLRs) for improved Performance in Distributed Systems

Distributed system has quite a lot of servers to attain increased availability of service and for fault tolerance. Balancing the load among these servers is an important task to achieve better performance. There are various hardware and software based load balancing solutions available. However there is always an overhead on Servers and the Load Balancer while communicating with each other and sharing their availability and the current load status information. Load balancer is always busy in listening to clients' request and redirecting them. It also needs to collect the servers' availability status frequently, to keep itself up-to-date. Servers are busy in not only providing service to clients but also sharing their current load information with load balancing algorithms. In this paper we have proposed and discussed the concept and system model for software based load balancer along with Availability-Checker and Load Reporters (LB-ACLRs) which reduces the overhead on server and the load balancer. We have also described the architectural components with their roles and responsibilities. We have presented a detailed analysis to show how our proposed Availability Checker significantly increases the performance of the system.

Temperature characteristics of optical parameters of phthalocyanine LB films and spin-coated films

The LB films and spin-coated films of tetra-neopentoxy phthalocyanine zinc (TNPPcZn) were prepared and annealed at different temperatures. Their refractive index (n) and extinction coefficient (k) were measured by p-polarized reflectance. The similar value of n and k, as well as similar changing tendency of it and k at varied annealing temperatures, was found between LB films and spin-coated films. In addition, the absorption curves of TNPPcZn LB films and spin-coated films in visible range at different annealing temperature were investigated. The results indicate that the changing tendency of the extinction coefficient of two kinds of TNPPcZn films obtained from two methods mentioned above were coincident. When the annealing temperature increased to 150 degrees C, the monomers of TNPPcZn films transformed to aggregates, n(f) and k(f) of the films increased. Further, n(f) and k(f) decreased as aggregates changed back to monomers again at the annealing temperature of 300 degrees C. The experimental results coincide well with the theoretical analysis. (C) 2004 Elsevier B.V. All rights reserved.

LB膜材料2-丙烯酰胺基十六烷磺酸及聚合物的合成、表征与LB膜研究

LB膜材料的合成研究是LB膜研究领域的核心问题。合成和制作了强度高、热稳定性好而且有特定功能性质的LB膜材料是将箭述广泛应用前景变为现实的关键，因此，功能性双亲单体和双来聚合物的合成及其在LB膜方面的应用是极为重要的研究课题。

（一）2，4－二甲基戊二烯基烯土氯化物的合成及其对丁二烯的聚合活性（二）酞菁铜衍生物 LB 膜材料的合成及其气敏特性

本文通过元素分析，红外光谱，热失重分析，质谱。X 光电子能谱的测定以及对化合水解产物的分析。确认合成了下列三种新型 2，4－二甲基戊二烯基稀土氯化物。（I）[2,4-(CH_3)_2C_5H_5]LnCl_2·nTHF (2,4-(CH_3)_2C_5H_5 = 2, 4－二甲基戊二烯基；Ln = Pr, Nd, Sm, Gd; n = 3)。（II）[2,4-(CH_3)_2C_5H_5]LnCl_2·nTHF (Ln = Pr, Nd; n = 2, 3)。（III）[2,4-(CH_3)_2C_5H_5]LnCl_2·nTHF (Ln = Nd, Sm; n = 1)。在稀土金属有机化合物中尚未见此类化合物的报导。化合物的质谱分析结果表明，配位的四氢呋喃分子容易从配合物分子中脱落，形成带一个四氢呋喃，甚至不带四氢呋喃的配合物。说明配合物分子中不带四氢呋喃的形式是较稳定的。化合物的 X 光电子能谱结果表明化合物不是混合物。化合物水解产物的定量气相色谱分析进一步证实所合成的化合物为我们所预期的产物。实验结果表明，单体转化率受溶剂影响较大。在以环戊烷为溶剂的聚合反应中，聚合活性较高。而以甲苯为溶剂的聚合反应中，其聚合活性较低。在主催化剂不变的条件下，改变 Al/Nd 摩尔比，单体的转化率有明显的变化。同一 Al/Nd 摩尔比，不同催化剂用量也对单体的转化率有较大的影响。对聚合物的微观结构分析表明，溶剂，铝钕摩尔比催化剂用量对聚丁二烯的顺－1，4 含量均有影响，但影响不大。

卟啉LB膜结构表征和电性质研究

利用膜天平、紫外-可见分光光度计、红外光谱仪、电子显微镜以及X-射线衍射仪等手段研究了新合成的尚未见文献报道的材料的界面膜和LB膜的性质和结构，对卟啉LB膜导电特性和气敏特性也进行了初步研究，得到下述结论：（1）利用预处理的新方法研究了界面膜的性质，研究结果表明预处理过程能用于判别界面膜的存在状态。（2）随着取代基上碳原子数增加，分子在水面上占据表观截面积呈现增大趋势。（3）取代链的长度对膜的沉积类型有重要影响，短链取代卟啉仅能以Z型方式沉积，而长链取代卟啉能以Y或Z型方式沉积。（4）取代侧链的长度对卟吩环取向影响较小，几种化合物的取向角在30°- 40°之间。（5）花生酸与TPIAPP掺杂后可减弱卟啉分子在LB膜中的相互作用。（6）取代链长度对膜结构的有序性有影响。短链取代卟啉不能给出布拉格衍射峰。（7）混合膜中，由于卟啉的混杂使花生酸的相变向低温方向移动，并有熔程变长的现象。（8）所研究材料的LB膜面的内导电能力较差，加入NH_3和NO_2后膜的电导不发生显著变化。

TMB·TCNQ和硬脂酸混合LB膜的制备及表征

将没有双亲性的电荷转移配合物TMB.TCNQ(TMB:3,3′,5,5-′Tetramethylbenzidine;TCNQ:7,7,8,8-tetracyanoquinodimethane)通过与硬脂酸混合组装制备了混合LB膜。TMB.TCNQ和硬脂酸的摩尔比例在1∶1,1∶2和1∶3的情况下都可以成功进行组装。利用紫外-可见-近红外光谱、透射和掠角反射红外光谱、X射线衍射以及原子力显微镜研究了混合LB膜中各组分的结构、分子取向和表面形貌等。

有效碳链长度与十八铵脂肪酸盐LB膜热行为的研究

制备了十八铵十二酸盐，十八铵十八酸盐，十八铵二十四酸盐LB膜，并用变温傅里叶变换红 外透射光谱研究了它们的热行为。十八铵二十四酸盐I。B膜的相变温度与十八铵十八盐LB膜的相变温度基 本一样，都是在80～90℃的温度区间内。以上结果说明，双长链化合物中，有效烃链长度取决于双链中的 较短的那个烃链，在十八铵二十四酸盐LB膜中，整个十八胺的长碳链都对膜的热稳定性有贡献，而二十四 酸的长碳链中则只有部分烃链有贡献。

2-十八烷基-7,7,8,8-四氰基对醌二甲烷和3,3′,5,5′-四甲基联苯胺电荷转移配合物LB膜的制备和表征

利用LB技术制备了2-十八烷基-7,7,8,8-四氰基对醌二甲烷(C18TCNQ)和3,3,′5,5′-四甲基联苯胺(TMB)的电荷转移配合物(CT comp lex)薄膜,即TMB.C18TCNQ LB膜.利用红外(IR)光谱、紫外-可见-近红外(UV-V is-NIR)光谱以及原子力显微镜(AFM)研究了TMB.C18TCNQ在LB膜中的分子取向、结构及表面形貌.结果表明,配合物为混合堆积类型,LB膜中电子给体TMB和电子受体C18TCNQ的环面分别垂直于固体基板表面,而且给体和受体以面对面的方式堆积.5层TMB.C18TCNQ LB膜的AFM照片显示,其表面形貌是由许多堆积在一起的六边形片状微晶组成的,微晶的宽度约为180 nm.与通过LB技术和掺杂技术制备的TMB.C18TCNQ掺杂膜比较,TMB.C18TCNQ LB膜具有明显不同的结构,其长的脂肪烃链有向垂直于基板表面方向变化的趋势,LB膜与掺杂膜的表面形貌也有明显不同.这表明不同的制备方法可以影响薄膜的结构和形貌.

LB films of 2-n-heptadecanoylbenzoic-rare earth and their luminescence properties

Several ultrathin luminescent Langmuir-Blodgett (LB) films have been prepared by using the subphase containing the rare earth ions (Eu3+, Tb3-). The effect of the rare earth ions on the monolayer of 2-n-heptadecanoylbenzoic acid (HBA) was investigated. IR and UV spectra showed the rare earth ions were bound to the carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The layer structure of the LB films was demonstrated by low-angle X-ray diffraction. UV absorbance intensity increases linearly with the number of LB films layers, which indicate that the LB films are homogeneously deposited. The LB films can give off strong fluorescence. and the signal can be detected from a single layer. The characteristic luminescence behaviors of LB films have been discussed compared with those of the complexes.

Luminescence properties of LB films based on heteropolytungstate of rare earth

In this work, the LB films based on heteropolytungstate of Dy and Sm have been prepared. The X-ray diffraction shows the LB films have a highly ordered lamella structure. The luminescence characteristics of the LB films were studied. The charge transfer bands of LB films are in higher energies than those of the corresponding solids. It is noticed that the yellow to blue intensity ratio (Y:B) of Dy3+ in the LB films is different from that of the solid. The differences in the spectra show that the Dy3+ site symmetry in LB film was changed due to the interaction between the surfactant and the polyanions. The differences could also be found in the luminescence spectra of the LB films of Sm complex.

Preparation and luminescence properties of LB films based on 4-hexadecyloxybenzoic terbium

LB films of 4-hexadecyloxybenzoic-terbium by using the subphase containing Tb3+ were prepared. The monolayer behavior of 4-hexadecyloxybenzoic acid (HOBA) on the subphase containing rare earth ions was studied. IR and UV spectra show that the rare earth ions were bound to carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The luminescence spectra show that the LB films have the fine luminescence properties, and the LB films emit strong luminescence under UV light irradiation.