Characterization of Polyimide Matrix Resins and Prepregs

Graphite/polyimide composite materials are attractive candidates for a wide range of aerospace applications. They have many of the virtues of graphite/epoxies, i.e., high specific strengths and stiffness, and also outstanding thermal/oxidative stability. Yet they are not widely used in the aerospace industry due to problems of procesability. By their nature, modern addition polyimide (PI) resins and prepregs are more complex than epoxies; the key to processing lies in characterizing and understanding the materials. Chemical and rheological characterizations are carried out on several addition polyimide resins and graphite reinforced prepregs, including those based on PMR-15, LARC 160 (AP 22), LARC 160 (Curithane 103) and V378A. The use of a high range torque transducer with a Rheometrics mechanical spectrometer allows rheological data to be generated on prepreg materials as well as neat resins. The use of prepreg samples instead of neat resins eliminates the need for preimidization of the samples and the data correlates well with processing behavior found in the shop. Rheological characterization of the resins and prepregs finds significant differences not readily detected by conventional chemical characterization techniques

Chemical and rheological evaluation of polymides

Chemical and rheological evaluation techniques were developed for polyimide composite matrix resins. LARC 160 (AP-22), LARC 160 (Curithane 103), PMR 15 and PISO2 resins were investigated. Liquid and solid state rheological techniques were used to develop processing parameters and woven graphite reinforced laminates were successfully fabricated, using these processing parameters

Development of LaRC 160/NR150B2 polyimide graphite hybrid composites

A method for co-curing NR150B2 and LaRC 160 prepregs into hybrid composites was developed. The processing characteristics and the properties of the hybrid composites were compared with those of laminates fabricated from the individual component prepregs. Resin forms were selected and optimized and a new NR150 formulation was investigated. The new formulation greatly facilitated the processing and the performance of this system. Quality control techniques were evaluated and developed, high quality laminates were fabricated from both individual resin systems, and hybrid laminates were successfully co-cured. Optimum hybrid forms were investigated and several novel approaches were explored. An optimum hybrid system was developed that utilizes a LaRC curing schedule but shows no degradation of mechanical properties after aging 500 hr in air at 260 C

An Epidemic Model of Violence and Public Support in Civil War

How do civilians respond to violence in civil war, and how do these responses shape combatants’ coercive strategies? Conventional wisdom expects civilian victimization to backfire, as a security-minded public “balances” against the side posing the greatest threat to its livelihood and survival. Yet combatants often expect a terrorized population to do the opposite, “bandwagoning” with those most willing and capable to inflict harm. Using an epidemic model of popular support dynamics, I explore the logic of balancing and bandwagoning in irregular civil war. I argue that when civilian strategy is clearly communicated to combatants, civilians are always better off balancing, and combatants are better off avoiding punishment. When civilian choice is not observed, the balancing equilibrium breaks down and patterns of violence depend on the local balance of power. The model’s results challenge the view that selective violence is most common in areas of incomplete control. Due to uncertainty over civilian behavior, violence in both divided and perfectly controlled areas can occur in equilibrium, inflicting great costs on civilians. I compare these predictions against the historical record of Soviet counterinsurgency in Western Ukraine, using new micro-level data from the declassified archives of the Soviet secret police.Governmen

Denial and Punishment in the North Caucasus: Evaluating the Effectiveness of Coercive Counter-Insurgency

A growing literature on the subnational diffusion of armed conflict rests on the proposition that political violence triggers more violence, in the same locality and elsewhere. Yet state efforts to contain such uprisings remain largely unexplored, theoretically and empirically. Drawing on a mathematical model of epidemics, we formalize the logic of conflict diffusion and derive conditions under which state coercion might limit the spread of insurgent violence. Using a new dataset of insurgent and government violence in Russia's North Caucasus from 2000-2008, we evaluate the relative effectiveness of four coercive strategies: (1) denial, which manipulates the costs of expanding insurgent activity to new locations, (2) punishment, which manipulates the costs of sustained fighting in contested areas, (3) denial and punishment, which does both, and (4) no action, which does neither. We find denial to be most effective at containing insurgent violence. Punishment is least effective, and even counterproductive. Not only does such a strategy fail to prevent the spillover of violence to new locations, but it may amplify the risk of continued fighting in contested areas. In the Caucasus, denial is found to be the least inflammatory counterinsurgency option for Russia. For it to succeed, Russia should physically isolate centers of insurgent activity from regions of non-violence, avoid the temptation of punitive reprisals, limit the insurgent's options, and convince him that he cannot succeed.Governmen

Integrated project management system of scientific and technical centre in oil company "Rosneft"

Concept and structure of three level integrated project management system of in project-oriented organization have been suggested and described. Synergetic effect at such system introduction is achieved due to systemic actions in such directions as: increasing organization controllability and transparence of decision making; flow of documentation regulation; formalization and optimization of project activity; development of irredundant and consistent system of normative documents in all directions of organization activit

Microwave sensor for noninvasive measurement of alcohol content in blood and distilled water

Měření alkoholu v krvi je jedním z druhů vyšetření, která se v medicíně používají nejčastěji. Změny koncentrace etanolu v krvi mění i její dielektrické charakteristiky, které je možné neinvazivně detekovat pomocí mikrovlnného senzoru. V této práci byly změřeny dielektrické parametry roztoků vody a ethanolu a krve a ethanolu v různých koncentracích. Na základě výsledků měření v programu MATLAB byl ve tvaru polynomu vytvořen matematický model závislosti relativní permittivity a vodivosti na koncentraci alkoholu v roztoků. Tento model byl využit pro modelování a simulaci senzoru v programu ,,Sim4life".Blood alcohol measurement is one of the most commonly used examinations in medicine. Fluctuations in concentration of ethanol in blood are the cause of changes in its dielectric characteristics, which can be non-invasively detected using a microwave sensor. In this work the dielectric parameters of water and ethanol and blood and ethanol solutions were measured for different concentrations. A mathematical model of dependence of relative permittivity and conductivity on the concentration of alcohol was created in MATLAB based on the measurement results in form of polynomial. This model was used to simulate the sensor in the "Sim4life" program

Identification of the portfolio of purchased motorsport parts and suggestions for changes to optimize purchasing processes.

Tato práce se zabývá procesem nákupu v jedné automobilové společnosti. Cílem práce je připravit dodavatelské portfolio dílů pro nový firemní projekt, kategorizovat díly, analyzovat nákupní proces oddělení, identifikovat silné a slabé stránky a doporučit zlepšení. Celá práce je rozdělena do dvou částí: teoretické a praktické. Teoretická část popisuje úrovně řízení podniku, podrobněji popisuje procesní řízení, nákupní procesy, dodavatelský řetězec a jeho charakteristiku, specifika procesů a výběr dodavatelů v automobilovém průmyslu a dotýká se také tématu typů výroby v automobilovém průmyslu. V praktické části byly kategorizovány díly konkrétního firemního projektu pro další sestavení dodavatelského portfolia, analyzován současný vnější a vnitřní stav společnosti, byly nabídnuty tipy k vyhledání dodavatelů pro nový projekt, popsán proces zadávání zakázek společnosti, provedena analýza a byla navržena zlepšení.This thesis deals with the purchasing process in an automobile company. The aim of the thesis is to prepare a supplier portfolio of parts for a new company project, categorize parts, analyze the purchasing process of the department, identify strengths and weaknesses and recommend improvements. The entire thesis is divided into two parts: theoretical and practical. The theoretical part describes the levels of business management, describes in more detail process man-agement, purchasing processes, the supply chain and its characteristics, the specifics of processes and the selection of suppliers in the automotive industry, and also touches on the topic of types of production in the automotive industry. In the practical part, the parts of a specific company project were categorized for the further compilation of the supplier portfolio, the current external and internal state of the company was analyzed, tips were offered for finding suppliers for a new project, the company's procurement process was described, an analysis was carried out and improvements were proposed

DEVELOPMENT AND EVALUATION OF THE "QUESTION-SOLUTION-REFLECTION" FRAMEWORK

It is agreed upon in the literature that reflection is a vital part of learning, yet it is seldom focused on in the physics education context. This presentation will summarise three studies into reflective thinking in the physics education multimedia context, and the development of the “question-solution-reflection” framework. According to Dewey (1933) and Rogers (2002), reflection can be thought of containing phases - • An experience, and the spontaneous interpretation of that experience • The articulation of the problem or question that arises out of the experience • The generation of possible explanations for the question • The explanations need to be examined and tested The videos used, and developed for the present studies, followed these phases. In the first video, an experience was shown, and a question was asked. The students wrote down their answers to the question, and then watched the second video, which contained the solutions. The students were prompted to write down if they changed their answers, and the reasons for doing or not doing so. Over 3000 responses to this format have been received as part of the three studies, and we argue that the results show that this framework is effective at promoting reflective thinking. REFERENCES Dewey, J. (1933). How we think. Courier Corporation. Rodgers, C. (2002). Defining reflection: Another look at John Dewey and reflective thinking. Teachers College Record, 104(4), 842-866

Annotated bibliography of α-benzildioxime

The references are presented chronologically. The names and configurations used by each author are retained. In this regard it should be noted that the presently accepted configuration of α-benzildioxime (anti) was not proposed until 1921, and was not generally accepted until somewhat later. The syn-configuration was generally used before 1921