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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Patterning of Nanostructures by Block Copolymer Self-Assembly

Zhang, Xiaojiang Unknown Date
No description available.
202

Geology, geochronology, thermobarometry, and tectonic evolution of the Queen Maud block, Churchill craton, Nunavut, Canada

Tersmette, Daniel B. Unknown Date
No description available.
203

Mathematical Programming for Sequence Optimization in Block Cave Mining

Pourrahimian, Yashar Unknown Date
No description available.
204

Uncapping the volcano : Malcolm Lowry, literary creativity, and writer's block

Sinclair, Struan January 1995 (has links)
Literary creativity and its shadow, the phenomenon popularly referred to as writer's block, have historically been accorded little attention by literary studies. In my thesis I seek to redress this oversight, illustrating my argument with reference to the creative life and works of Malcolm Lowry. I begin by arguing for a model of literary creativity that takes seriously the roles played by plans and intentions in motivating, sustaining and appropriately terminating literary creative action. I employ this model in order to provide a basis from which to clarify Lowry's own creative method. / I go on to rehearse and evaluate definitions and theories of writer's block from a variety of research paradigms. From these accounts I distill some important general features of writer's block. I argue that writer's block typically occurs as an intervention between stages of the literary creative process. / Finally, I return to detailed consideration of Lowry's creative method. I investigate three critical periods of writer's block in Lowry's later life and examine these interventions with reference to circumstantial, methodological and goal-based considerations. I conclude by drawing attention to the importance for literary studies of an accurate and comprehensive understanding of both literary creativity and writer's block.
205

Cable Monitoring Unit : Safety Ground Detection Through Capacitive Coupling

Norman, Mattias January 2014 (has links)
Electronically monitoring whether or not your car block heater is connected to a mains outlet might at first seem like an arbitrary task. A device installed in the comfort of the car seating area, which tells the user at every startup whether or not his/her car is connected to a mains outlet, could have market appeal though. But in order for it to be a worthwhile idea to pursuit, a certain requirement has to be met. It has to be able to be able to accurately detect whether or not the car is connected, through a single connection; the car ground. A certain part of the voltage in the phase of the mains will be capacitively coupled upon the safety ground. By exploiting the fact that the car ground will be connected to the mains safety ground when the block heater cable is in use, a device which can detect that coupled voltage could possibly be developed. In other words, a cable monitoring unit which in actuality detects a connection to the mains safety ground through capacitive coupling, hence the title of this dissertation. This work sets out to taking appropriate measurements to find out whether or not this proposed method of safety ground detection is valid, with heavy emphasis on whether or not it is applicable to a cable monitoring unit. According to the measurement results, an appropriate device is developed. A device which can fill the function described in the previous paragraph. Development of such a device involves; proper method of supplying power which upholds a galvanically isolated floating ground, signal processing, reliable detection mechanism, and considerations to how unintentional capacitive coupling behaves. A theoretical model of the device is put forth, as well as an actual rough prototype to in practice try to prove that the concept and method is valid. Downsides and problems with the device are discussed, such as upholding an effective detection system without making the device hard and cumbersome to use. Possible solutions to these problems are also proposed. The possible future of the concept of this device is also touched upon.
206

The relationship between (16,6,3)-balanced incomplete block designs and (25,12) self-orthogonal codes

Nasr Esfahani, Navid 21 August 2014 (has links)
Balanced Incomplete Block Designs and Binary Linear Codes are two combinatorial designs. Due to the vast application of codes in communication the field of coding theory progressed more rapidly than many other fields of combinatorial designs. On the other hand, Block Designs are applicable in statistics and designing experiments in different fields, such as biology, medicine, and agriculture. Finding the relationship between instances of these two designs can be useful in constructing instances of one from the other. Applying the properties of codes to corresponding instances of Balanced Incomplete Block Designs has been used previously to show the non-existence of some designs. In this research the relationship between (16,6,3)-designs and (25,12) codes was determined.
207

Function Block Algorithms for Adaptive Robotic Control

Egaña Iztueta, Lander, Roda Martínez, Javier January 2014 (has links)
The purpose of this project is the creation of an adaptive Function Block control system, and the implementation of Artificial Intelligence integrated within the Function Block control system, using IEC 61499 standard to control an ABB 6-axis virtual robot, simulated in the software RobotStudio. To develop these objectives, we studied a lot of necessary concepts and how to use three different softwares. To learn how to use the softwares, some tests were carried out. RobotStudio is a program developed by ABB Robotics Company where an ABB robot and a station are simulated. There, we designed and created a virtual assembly cell with the virtual IRB140 robot and the necessary pieces to simulate the system. To control the robot and the direct access to the different tools of RobotStudio, it is necessary to use an application programming interface (API) developed by ABB Robotics Company. C sharp (C#) language is used to program using the API, but this language is not supported by the Function Block programming software nxtStudio. Because of this, we used VisualStudio software. In this software, we use the API libraries to start and stop the robot and load a RAPID file in the controller. In a RAPID file the instructions that the robot must follow are written. So, we had to learn about how to program in C# language and how to use VisualStudio software. Also, to learn about IEC 61499 standard it was necessary to read some books. This standard determines how an application should be programmed through function blocks. A function block is a unit of program with a certain functionality which contains data and variables that can be manipulated in the same function block by several algorithms. To program in this standard we learnt how to use nxtStudio software, consuming a lot of time because the program is quite complex and it is not much used in the industrial world yet. Some tests were performed to learn different programing skills in this standard, such as how to use UDP communication protocol and how to program interfaces. Learning UDP communication was really useful because it is necessary for communication between nxtStudio and other programs, and also learning how to use interfaces to let the user access the program. Once we had learnt about how to use and program the different softwares and languages, we began to program the project. Then, we had some troubles with nxtStudio because strings longer than fourteen characters cannot be used here. So, a motion alarm was developed in VisualStudio program. And another important limitation of nxtStudio is that C++ language cannot be used. Therefore, the creation of an Artificial Intelligence system was not possible. So, we created a Function Block control system. This system is a logistical system realised through loops, conditions and counters. All this makes the robot more adaptive. As the AI could not be carried out because of the different limitations, we theoretically designed the AI system. It will be possible to implement the AI when the limitations and the problems are solved.
208

Block scheduling and its impact on graduation rates in Indiana public secondary schools

Harkin, Linda Joan January 2001 (has links)
The purpose of this study was to examine the graduation rates of secondary schools in Indiana in 1989-90 and to compare those graduation rates to those of 199798, to see if those schools that adopted block scheduling had experienced a difference in graduation rates either positively or negatively. A comparison was also made of graduation rates between schools adopting block scheduling for at least three years and traditional schools during this same time period. Further examination was made to determine if any specific type of block schedule had improved graduation rates. The size school was also a consideration as to the affect of block scheduling on graduation rates. The study also sought to determine if block scheduling had an impact on attendance rates, discipline incidents, pupil teacher ratio, or full time teacher equivalency, all factors aligned to reasons why students drop out of school.The population for this study consisted of 251 Indiana public secondary schools, 203 schools which maintained a traditional schedule and 48 schools identified by the Indiana Department of Education to have adopted block scheduling prior to or including 1995-96, 1996-97, 1997-98. Nine research questions accompanied by Null Hypotheses for each were determined and tested. All data collection were from the Indiana Department of Education through reports compiled and generated from information submitted annually by all public schools in Indiana. / Department of Educational Leadership
209

Block LU simulation with an Approximate Model of Coregionalization

Wang, Tong 11 1900 (has links)
Geostatistical techniques are used to estimate recoverable reserves at unsampled locations and to quantify uncertainty. Several variables are often measured and important for reserve evaluation. Using more variables improves the quality of modeling, but quantifying the relationships between the variables is difficult. The traditional linear model of coregionalization has been used to quantify the relationship between multiple variables, but ensuring the mathematical validity of the model is cumbersome. This research proposes an approximate method that improves the speed and practicality of the numerical modeling process by easily modeling multiple regionalized variables. The proposed algorithm is based on block LU simulation and takes local transformation into consideration. Application to a nickel deposit demonstrates the proposed methodology. / Mining Engineering
210

CONTROL OF KEY POLYMER PROPERTIES VIA REVERSIBLE ADDITION-FRAGMENTATION CHAIN TRANSFER IN EMULSION POLYMERIZATION

Altarawneh, Ibrahem January 2009 (has links)
Doctor of Philosophy (PhD), Engineerig / Free radical emulsion polymerization (FRP) is widely adopted in industry due to its applicability to a wide range of monomers. Despite its many benefits and wide spread use, the fast chain growth and the presence of rapid irreversible termination impose limitations with respect to the degree of control in FRP. Furthermore, producing block copolymers and polymers with complex structures via FRP is not feasible. Closer control of macromolecular chain structure and molar mass, using novel polymerization techniques, is required to synthesize and optimize many new polymer products. Reversible addition fragmentation chain transfer (RAFT)-mediated polymerization is a novel controlled living free radical technique used to impart living characters in free radical polymerization. In combination with emulsion polymerization, the process is industrially promising and attractive for the production of tailored polymeric products. It allows for the production of particles with specially-tailored properties, including size, composition, morphology, and molecular weights. The mechanism of RAFT process and the effect of participating groups were discussed with reviews on the previous work on rate retardation. A mathematical model accounting for the effect of concentrations of propagating, intermediate, dormant and dead chains was developed based on their reaction pathways. The model was combined with a chain-length dependent termination model in order to account for the decreased termination rate. The model was validated against experimental data for solution and bulk polymerizations of styrene. The role of the intermediate radical and the effect of RAFT agent on the chain length dependent termination rate were addressed theoretically. The developed kinetic model was used with validated kinetic parameters to assess the observed retardation in solution polymerization of styrene with high active RAFT agent (cumyl dithiobenzoate). The fragmentation rate coefficient was used as a model parameter, and a value equal to 6×104 s-1 was found to provide a good agreement with the experimental data. The model predictions indicated that the observed retardation could be attributed to the cross termination of the intermediate radical and, to some extent, to the RAFT effect on increasing the average termination rate coefficient. The model predictions showed that to preserve the living nature of RAFT polymerization, a low initiator concentration is recommended. In line with the experimental data, model simulations revealed that the intermediate radical prefers fragmentation in the direction of the reactant. The application of RAFT process has also been extended to emulsion polymerization of styrene. A comprehensive dynamic model for batch and semi-batch emulsion polymerizations with a reversible addition-fragmentation chain transfer process was developed. To account for the integration of the RAFT process, new modifications were added to the kinetics of zero-one emulsion polymerization. The developed model was designed to predict key polymer properties such as: average particle size, conversion, particle size distribution (PSD), and molecular weight distribution (MWD) and its averages. The model was checked for emulsion polymerization processes of styrene with O-ethylxanthyl ethyl propionate as a RAFT based transfer agent. By using the model to investigate the effect of RAFT agent on the polymerization attributes, it was found that the rate of polymerization and the average size of the latex particles decreased with increasing amount of RAFT agent. It was also found that the molecular weight distribution could be controlled, as it is strongly influenced by the presence of the RAFT based transfer agent. The effects of RAFT agent, surfactant (SDS), initiator (KPS) and temperature were further investigated under semi-batch conditions. Monomer conversion, MWD and PSD were found to be strongly affected by monomer feed rate. With semi-batch mode, Mn and <r> increased with increasing monomer flow rate. Initiator concentration had a significant effect on PSD. The results suggest that living polymerization can be approached by operating under semi-batch conditions where a linear growth of polymer molecular weight with conversion was obtained. The lack of online instrumentation was the main reason for developing our calorimetry-based soft-sensor. The rate of polymerization, which is proportional to the heat of reaction, was estimated and integrated to obtain the overall monomer conversion. The calorimetric model developed was found to be capable of estimating polymer molecular weight via simultaneous estimation of monomer and RAFT agent concentrations. The model was validated with batch and semi-batch emulsion polymerization of styrene with and without RAFT agent. The results show good agreement between measured conversion profiles by calorimetry with those measured by the gravimetric technique. Additionally, the number average molecular weight results measured by SEC (GPC) with double detections compare well with those calculated by the calorimetric model. Application of the offline dynamic optimisation to the emulsion polymerization process of styrene was investigated for the PSD, MWD and monomer conversion. The optimal profiles obtained were then validated experimentally and a good agreement was obtained. The gained knowledge has been further applied to produce polymeric particles containing block copolymers. First, methyl acrylate, butyl acrylate and styrene were polymerized separately to produce the first block. Subsequently, the produced homopolymer attached with xanthate was chain-extended with another monomer to produce block copolymer under batch conditions. Due to the formation of new particles during the second stage batch polymerization, homopolymer was formed and the block copolymer produced was not of high purity. The process was further optimized by operating under semi-batch conditions. The choice of block sequence was found to be important in reducing the influence of terminated chains on the distributions of polymer obtained. It has been found that polymerizing styrene first followed by the high active acrylate monomers resulted in purer block copolymer with low polydispersity confirmed by GPC and H-NMR analysis.

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