MANET下服务发现系统的实现、建模和优化

随着移动自组织网络（MANET）的日益普及，这种网络环境下的应用需求越来越多，服务发现系统是支撑这些应用的基础服务之一，它帮助用户在移动环境中发布、管理、发现和使用种类繁多的服务。 学术界和工业界对MANET下服务发现已经进行了很多探索和研究，但是已有研究多是构造有目录服务器的发现系统，它需要网络中存在能力比较强且稳定的节点充当目录服务器，这种模式并不适用于所有场景。到目前为止，无目录服务器的服务发现系统的构造相对较少且技术尚不成熟，存在较多问题需要解决。另外，针对不同的服务发现系统还没有一种普遍可行的系统建模和性能分析的方法。 本文针对MANET环境下不同的应用场景，改进了有目录服务器的发现系统SCN4M（Service CatalogNet for MANET），设计和实现了无目录服务器的发现系统SCN4M-DL（Service CatalogNet for MANET-DirectoryLess）。论文在SCN4M中引入了多种服务匹配策略包括近似匹配算法、基于正则表达式的匹配算法，同时提出了基于系统负载的自适应匹配策略调整机制，即通过引入请求队列队长作为控制变量，决定变换匹配策略的时机，以此加快或降低匹配处理速度。在SCN4M-DL中采用跨层设计思想，提出了面向区域的混合式地理位置路由算法，分阶段地使用贪心路由、面路由和面向服务发现的环形路由；并在此基础之上，实现了基于地理位置信息的服务注册、管理和发现。在两个系统中都使用了排队论对系统中的单个节点进行建模和优化。在SCN4M中通过扩展的有多服务速率的M/M+/1模型，得出了系统吞吐量、系统等待队长、系统平均调整次数的表达式，实际系统的运行结果验证了模型的适用性，论文依据模型给出了SCN4M在评价指标QoS指导下的优化的运行方案设计。在SCN4M-DL中，通过应用改进的串联排队论模型，将本地的发现过程分成了二个独立的阶段，然后，将SCN4M中的M/M+/1模型成功应用于第二阶段，论文也给出了SCN4M-DL的优化方案。

实时数据库缓冲区管理算法的设计和实现

分析了实时数据库的事务特征,对以往的研究成果进行了总结,以满足事务的按时完成比率(SuccessRatio)为目标,为实时系统设计了一种使用反馈控制思想的基于优先级的实时数据库缓冲区管理算法FCLRU2 dl,并将该算法与常用的实时数据库事务调度算法和并发控制策略配合进行了测试和评估,证明了算法的优越性。实验中得到的另一个结论是在特定的事务调度算法和并发控制策略下,实时数据库不需要全部位于内存中,可以不是内存数据库。

Experimental Investigation on Propane Hydrate Dissociation by High Concentration Methanol and Ethylene Glycol Solution Injection

The dissociation behaviors of propane hydrate by high concentration alcohols inhibitors injection were investigated. Methanol (30.0, 60.1, 80.2, and 99.5 wt %) and ethylene glycol (30.0, 60.1, 69.8, 80.2, and 99.5 wt %) solution were injected, respectively, as alcohols inhibitors in 3.5 L transparent reactor. It is shown that the average dissociation rates of propane hydrate injecting methanol and ethylene glycol solution are 0.02059-0.04535 and 0.0302-0.0606 mol.min(-1).L-1, respectively. The average dissociation rates increase with the mass concentration increase of alcohols solution, and it is the biggest when 99.5 wt % ethylene glycol solution was injected. The presence of alcohols accelerates gas hydrate dissociation and reduces the total need of external energy to dissociate the hydrates. Density differences act as driving force, causing the acceleration effects of ethylene glycol on dissociation behaviors of propane hydrate are better than that of methanol with the same injecting flux and mass concentration.

Effect of microwave on formation/decomposition of natural gas hydrate

Natural gas hydrate (NGH) reservoirs have been considered as a substantial future clean energy resource and how to recover gas from these reservoirs feasibly and economically is very important. Microwave heating will be taken as a promising method for gas production from gas hydrates for its advantages of fast heat transfer and flexible application. In this work, we investigate the formation/decomposition behavior of natural gas hydrate with different power of microwave (2450MHZ), preliminarily analyze the impact of microwave on phase equilibrium of gas hydrate,and make calculation based on van der Waals-Platteeuw model. It is found that microwave of a certain amount of power can reduce the induction time and sub-cooling degree of NGH formation, e.g., 20W microwave power can lead to a decrease of about 3A degrees C in sub-cooling degree and the shortening of induction time from 4.5 hours to 1.3 hours. Microwave can make rapid NGH decomposition, and water from NGH decomposition accelerates the decomposition of NGH with the decomposition of NGH. Under the same pressure, microwave can increase NGH phase equilibrium temperature. Different dielectric properties of each composition of NGH may cause a distinct difference in temperature in the process of NGH decomposition. Therefore, NGH decomposition by microwave can be affected by many factors.

Vacuum pyrolysis of waste tires with basic additives

Granules of waste tires were pyrolyzed tinder vacuum (3.5-10 kPa) conditions, and the effects of temperature and basic additives (Na2CO3, NaOH) on the properties of pyrolysis were thoroughly investigated. It was obvious that with or without basic additives, pyrolysis oil yield increased gradually to a maximum and subsequently decreased with a temperature increase from 450 degrees C to 600 degrees C, irrespective of the addition of basic additives to the reactor. The addition of NaOH facilitated pyrolysis dramatically, as a maximal pyrolysis oil yield of about 48 wt% was achieved at 550 degrees C without the addition of basic additives, while a maximal pyrolysis oil yield of about 50 wt% was achieved at 480 degrees C by adding 3 wt% (w/w, powder/waste tire granules) of NaOH powder. The composition analysis of pyrolytic naphtha (i.b.p. (initial boiling point) similar to 205 degrees C) distilled from pyrolysis oil showed that more dl-limonene was obtained with basic additives and the maximal content of dl-limonene in pyrolysis oil was 12.39 wt% which is a valuable and widely-used fine chemical. However, no improvement in pyrolysis was observed with Na2CO3 addition. Pyrolysis gas was mainly composed of H-2, CO, CH4, CO2, C2H4 and C2H6. Pyrolytic char had a surface area comparable to commercial carbon black, but its proportion of ash (above 11.5 wt%) was much higher.

In situ hydrate dissociation using microwave heating: Preliminary study

In this work, we investigate the dissociation behavior of natural gas hydrate in a closed system with microwave (MW) heating and hot water heating. The hydrate was formed at temperatures of 1-4 degrees C and pressures of 4.5-5.5 MPa. It was found that the gas hydrate dissociated more rapidly with microwave than with hot water heating. The rate of hydrate dissociation increased with increasing microwave power, and it was a function of microwave power. Furthermore, the temperature of the hydrate increased linearly with time during the microwave radiation.

Influence of 3A molecular sieve to tetrahydrofuran(THF) hydrate formation

Visual observation of the THF hydrate formation process in the presence of a 3A molecular sieve has been made at normal atmosphere and below a temperature of zero by microscopy. The results indicate that a 3A molecular sieve can induce the nucleation of the THF hydrate and promote the THF hydrate growth. With the existence of a 3A molecular sieve, the growth rate of THF hydrate is between 0.01 and 0.05 mu m/s. In comparison with the system without any 3A molecular sieve, the growth rate increases about 4 nm/s. After the THF hydrate grows into megacryst, the crystals will recombine and partially change under the same condition.

Use of electrical resistance to detect the formation and decomposition of methane hydrate

The changes of electrical resistance (R) were studied experimentally in the process of CH4 hydrate formation and decomposition, using temperature and pressure as the auxiliary detecting methods simultaneously. The experiment results show that R increases with hydrate formation and decreases with hydrate decompositon. R is more sensitive to hydrate formation and decompositon than temperature or pressure, which indicates that the detection of R will be an effective means for detecting natural gas hydrate (NGH) quantitatively.

Clathrate Dissociation Conditions for Methane + Tetra-n-butyl Ammonium Bromide (TBAB) + Water

Hydrate equilibrium data of the CH4 + tetra-n-butyl ammonium bromide (TBAB) + water have been measured by using the isothermal pressure search method for four components of TBAB aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric TBAB solution. Moreover, methane uptake into semi-clathrates is confirmed by a shift in the clathrate regions when methane is present. The experiments are carried out in the pressure range of (0.5 to 11) MPa and in the temperature range of (281.15 to 295.15) K.

Multi-exponentially photoelectric response of bacteriorhodopsin

A thin oriented bacteriorhodopsin (bR) him is deposited on a stainless steel slide by use of the electrophoretic sedimentation method. A junction is made with electrolyte gels having a counterelectrode to construct a bR-based photoelectric detector;. The photoelectric response signal to a 10 ns laser pulse is measured. A theory on the photoelectric kinetics of bR is developed based on the concept of the charge displacement current and the bR photocycle rate equations. Comparison between the theoretical and experimental results proves that the bR photoelectric response to a short laser pulse is a multi-exponential process. The decay time constants and amplitudes of each, exponential component are obtained by data fitting.

Kinetics of picosecond laser pulse induced charge separation and proton transfer in bacteriorhodopsin

Bacteriorhodopsin (BR) films oriented by an electrophoretic method are deposited on a transparent conductive ITO glass. A counterelectrode of copper and gelose gel is used to compose a sandwich-type photodetector with the structure of ITO/BR film/gelose gel/Cu. A single 30-ps laser pulse and a mode-locked pulse train are respectively used to excite the BR photodetector. The ultrafast failing edge and the bipolar response signal are measured by the digital oscilloscope under seven different time ranges. Marquardt nonlinear least squares fitting is used to fit all the experimental data and a good fitting equation is found to describe the kinetic process of the photoelectric signal. Data fitting resolves six exponential components that can be assigned to a seven-step BR photocycle model: BR-->K-->KL-->L-->M-->N-->O-->BR. Comparing tests of the BR photodetector with a 100-ps Si PIN photodiode demonstrates that this type of BIR photocletector has at least 100-ps response time and can also serve as a fast photoelectric switch. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

由氯代苯配合成聚酞亚胺方法的研究

聚酞亚胺作为一类最重要的耐热高分子，具有广泛的应用领域。但较高的合成成本使其不能象聚烯烃类高分子材料一样被广泛应用。本工作的目的是以氯代苯配‘和二胺为原料，制备双氯代酞酰亚胺单体，然后进行聚酞亚胺合成方法的研究，以达到减少合成步骤，降低其生产成本的目的，主要内容如下：1）由双氯代酞酞亚胺与双酚A在不同体系中进行（亲核取代）聚合反应，发现双酚是否完全成盐和聚合体系含水量是决定聚合物分子量的关键因素。所得聚合物比浓对数乳度在0.5 dL／g以上，并且试验重现性好。2）尝试以无水Na2S为缩合剂，与双氯代酞酞亚胺直接合成聚硫醚酞亚胺及双氯代酞酞亚肢和4，4-二氯二苯酮或4，4-二氯二苯矾合成聚硫（醚酞亚胺一酮）或聚硫（醚酞亚胺一矾），由于高纯的无水Na2S难于获得。因此聚合物的分子量较低。3）通过对微波和常规两种加热条件下聚合反应条件的对比。发现微波辐照聚合反应可以大大减少聚合反应的时间，并相应提高聚合物的分子量。4）由氯代苯配与二胺缩合合成了对称双氯单体，通过Ni催化偶联反应合成了一系列联苯型聚酰亚胺。与传统的由氯代苯配合成联苯二配相比，减少2-4步合成反应。由含有侧基的二胺合成的双（4-氯代酞酞亚胺）单体经催化偶联聚合获得了高分子量的聚酞亚胺，而由刚性直链二胺合成！）勺双（4-氯代酞酞亚服）单体生成的聚合物由于溶解性差，所以分子量较低。而双（3-氯代酞酰亚胺）单体聚合生成了大量的齐聚物而导致分子量较低。5）建立了一种合成不对称双氯代酞酞亚胺简易的方法。6）由不刘”称双氯单体合成的联苯型聚酰亚胺具有良好的溶解性和成膜性。应用13C NMR谱对其联苯结构单元的组成进行分析的结果表明：2,3,3',4-双亚胺：2,2',3,3,-双亚胺:3,4,3·，4'-双亚胺＝58.0: 21.0:21.0。与其它同分异构聚酞亚胺酞比，由不对称单体合成的聚酞亚胺具有最高的玻璃化转变温度。

Friedel-crafts反应合成芳香环状齐聚物与开环聚合

芳香环状低聚物的合成是二十世纪八十年代末发展起来的研究领域，其特有的环状结构和可进行可控的开环聚合决定了芳香环状低聚物具有广阔的应用前景。本文从研究单体结构与成环反应的关系出发，开拓了一种合成芳香环状聚醚酮的新方法—改进的Friedel-Crafte反应法，采用该方法成功地合成了一系列新型结构的大环化合物，并首次利用流变仪对开环聚合过程中的流变行为进行了较为系统的观测。根据acoson-Stockmayer环化理论，应用基质辅助激光解吸离子化飞行时间质谱（MAIDL-TOF MS），对一系列芳香环状低聚物组分分布进行分析，研究了芳香环状低聚物的产率、组分分布与单体结构的关系。结果表明：芳香聚醋、聚麟酸醋及芳香聚醚环状低聚物系列中，InCn与1nn呈良好的线性关系，符合J-S理论分布。环状齐聚物的产率与组分分布受单体的中心键角影响，单体的中心键角在100°～120°范围内，其中心键角愈小，γ值愈大。γ值愈大，反应产物中小环化合物的含量越高，而小环化合物的含量的增加是高产率地合成环状齐聚物的前提之一。在此理论的指导下，通过对单体结构的模拟，高选择性地合成了一种新型结构的芳香环状聚硫醋二聚体，对其结构进行了精确的表征，在不同溶剂中得到了该环状二聚体的单晶，单晶X闪ray衍射表明该二聚体为环张力极小的大环化合物。基于上述理论，以有利于成环的邻苯二酞氯为酞基化试剂，对Friedel-Crafts酞基化反应在合成芳香环状齐聚物中的应用进行了系统研究，开拓了一种合成芳香环状预聚体的新方法—改进的Friedel-Crafts酞基化反应法。发现反应体系中Lewis碱的存在有利于选择性地形成环状产物。并进一步确定反应最佳条件为： Lewis碱和催化剂Alcl3与富电单体的摩尔比分别为1.2和3.4; 1,2-二氯乙烷为本反应的最佳溶剂；等当量的反应单体要求缓慢滴加到形成“假高稀”的溶剂体系中；Lewis碱NMP，DMF等都适用于本反应体系。在此优化条件下，以邻苯二酞氯和间苯二酞氯为酞基化试剂，室温下，合成了一系列芳香环状聚醚酮酮、聚醚酮、聚醚矾酮等新型结构的环状齐聚物，利用MALDI-TOF-MS，NMR，GPC，FTIR，DSC，元素分析等手段对环状结构进行了精确的表征；DSC分析表明含邻苯二拨基结构的环状齐聚物为无定型材料；部分产物的产率高达90％。在阴离子引发剂联苯双酚钾存在下，制备的环状齐聚物成功进行了熔融开环聚合，得到了相应结构的高分子量的线性开环聚合产物。其中，含邻苯二拨基结构的环状聚醚酮酮、环状聚醚酮矾的开环聚合产物的比浓粘度分别达到0.42dL／g，0.36 dL／g（0.5％的DMF溶液，25士0.1℃）；四种含间苯二锁基结构的环状齐聚物的开环聚合产物的Tg与常规亲电沉淀反应合成的线性高聚物的Tg相同。含侧甲基的开环聚合产物的Tg比对应的开环聚合的产物的Tg高约5℃。研究结果表明用亲电缩聚方法制备芳香环状聚醚酮与亲核缩聚法相比较，具有成本低廉、反应条件温和丫产率高、易于大规模制备等优势，开拓了一种制备环状化合物的方法。自从美国G.E.公司利用环状聚碳酸酷的开环聚合制备线性聚碳酸醋以来，对芳香环状低聚物的开环聚合过程的研究仅局限在由GPC监测反应某一时刻的产物的分子量，而缺乏对与应用更为接近的开环聚合中的粘度的变化的研究。本文以界面缩聚反应高产率地合成芳香环状双酚A聚酷二聚体为对象，研究了流变仪在开环聚合中的应用。利用流变仪对环状二聚体开环聚合过程进行了较为系统的观测，研究了不同条件下的开环聚合中的流变行为，结果表明，开环聚合存在引发期，而且在引发期，熔融体的粘度低于10Pa·S，超过引发期，粘度呈指数级增长。引发期的长短可以通过引发剂的种类、浓度、开环聚合的温度等条件进行有效地控制。芳香环状聚酷二聚体与环状聚碳酸醋的开环共聚合的流变行为的研究结果表明：开环共聚合可以降低开环聚合的温度，调整引发期，是提高聚合产物的分子量的有效途径。用流变仪对以改进的Friedel-Crafts反应合成的芳香环酮齐聚物的开环聚合中的流变行为进行了监控。在330℃，剪切速率为0.05S-l下，熔融的环状齐聚物的粘度为2.0Pa·S。通过对开环聚合的反应条件的控制，同样实现了开环聚合的可控，通过改变其开环聚合的引发期的长短及粘度的变化规律，可、适应不。条一定为加工设计与成型加工提供理论指导和模型设计，必将进一步推进开环聚合工 艺向应用方向的发展。

镧系氨基酸配合物在生理pH条件下的结构特性及其对DNA的特异性识别

DNA是重要的生物大分子，也是主要的抗癌药物靶分子。小分子与DNA之间的相互作用是以DNA为靶分子的各种物质生物效应的基础，它们之间的特异性结合导致了癌变、突变及细胞的死亡。能够与DNA特异性结合的小分子很多都是临床上广泛应用的抗癌药物。因此，小分子与DNA之间的相互作用不论是对阐述抗癌、抗病毒药物的作用，还是对致癌机理的研究，尤其对抗癌药物的体内筛选都有重要意义。近十年来，开发新型的抗癌药物小分子，使它们具有对DNA序列特异性的识别能力己成为国内外研究的热点。斓系配合物由于具有广泛的光学、磁学和电学等特性使得有可能成为新的DNA特异性识别分子。然而，斓系离子在中性条件下极其容易水解的特性又极大的阻碍了斓系配合物对于DNA的识别性研究。本文在中性条件下合成了铜系氨基酸配合物，并成功的获得了这些配合物的晶体结构，利用这些有确定结构的I系氨基酸配合物与特定的DNA序列相作用，通过多种生物物理方法研究了它们对DNA序列特异性识别。主要的结果如下：1．在近中性条件下，合成了Eu-Val（［Eus_8（L-HVal）_(16)（H_2O）_(32)］Cl_(24)·12.5H_2O），Eu-Asp（［Eu_4（μ3-OH）_4（L-Asp）_2（L-HAsp）_3（H_2O）_7］Cl·11.5H_2O）和Tb-Cys（「Th_2（DL-Cys）_4（H_2O）_8]Cl_2）三种铜系氨基酸配合物，这些配合物的结构由于合成条件（温度，反离子及合成比例）上的差异与已报到的类似配合物的结构具有明显的不同。三种配合物的结构各具特色，从而在与DNA作用时将表现出各自特有的识别性能。2．Eu-Val配合物在与单链DNA作用时，配合物能键合到DNA碱基所在的疏水区，在与富含dC和dT碱基的序列相结合时，发生显著的能量传递，从而极大的增强了配合物中Eu的发射光谱。配合物结合DNA的化学计量比随序列中dC含量的降低而降低。配合物同样能够与处于DNA疏水区的富含dA和dG序列相结合，这种结合不能够产生能量传递，但使得DNA的紫外-可见光谱出现明显的减色和红移现象。此外，这一配合物还能够诱导单链DNApoly（dA）及p01y（rA）产生自身的二级结构，形成双链结构。这为进一步认识斓系离子的生物学效应奠定了基础，斓系氨基酸配合物可以诱导单链poly（dA）及poly（rA）形成自身结构尚无文献报道。3．Eu一AsP配合物能够选择性的稳定非B一构象的Poly（dA）Poly（dT），而使B一构象的印oly（dAdT）］2和［Poly（dGdC）］2变得不稳定。如在1：2比例时，该配合物可使Poly（dA）Polv（dT）的融化温度提高4℃，而使印oly（dAdT）｝2的融化温度降低6℃，［Poly（dGdC）］2则出现了两个转变温度。进一步的圆二色实验结果充分表明Eu一Asp配合物对于富含Poly（dA）Poly（dT）和［Poly（dAdT）］2的双链DNA没有构象上的改变，而对于［Poly（dGdC）］2的双链DNA则产生了显著的构象上的改变，很有可能正是这一改变使得［Poly（dGdC）］2变得极其的不稳定。配合物对［Poly（dGdC）］2的这种不稳定影响随着配合物浓度的逐步升高而越来越明显。变温实验结果清楚的表明，在37℃时，Eu-AsP使[Poly（dGdC）JZ发生了构象转化，并且这种转化是可逆的。4．Tb-Cys配合物与单链（除了poly（dA））和双链DNA都能发生能量传递，从而使得配合物的荧光显著增强。不同的DNA表现出不同的增强效果，表明TbCys配合物对DNA的序列存在选择性，单链要强于双链，富含Poly（dAdG）的序列增强效果最好。单链和双链能量传递的差异表明了配合物能够区分DNA的单链和双链，配合物在与单链作用时结合更强。TbCys配合物在与DNA作用时存在不同的结合位点，而且单链和双链的结合位点明显不同。TbCys配合物能够引起富含dC和dT的单链DNA发生减色效应，而能够引起富含poly（dA）、poly（dAdG）的单链DNA和富含poly（dA）poly（dT）、[Poly（dAdT）］2和［poly（dGdC）］2的双链DNA发生明显的红移。此外，这一配合物同样能够影响双链DNA的稳定性，使得富含poly（dA）Poly（dT）序列变得稳定，而使得富含印oly（dAdT）］2和富含印oly（dGdC）］2的序列变得不稳定。这些结果都表明了配合物对DNA存在选择性。比较不同配合物的差别后能够发现DNA对于不同的配合物同样具有选II择性，这种选择性能够用来区分配合物。一这些钢系氨基酸配合物由于选择了天然的氨基酸作为配体，从而大大的降低了对人体的毒性，进一步表现出的对不同的DNA序列的选择型则使其有望成为新型的抗癌诊疗试剂。