A method is described for the computer-aided layout of printed wiring boards. The type of board considered is a single sided board containing discrete components. The required input for the layout algorithm is coded from the relevant circuit diagram, together with a description of the component dimensions. This information is then stored within the computer in a data structure. The circuit components and their interconnections are represented by a set of nodes and branches. The principles of graph theory are used to construct an abstract model of the layout. A number of the nodes and branches of the circuit are first used in the construction of a planar graph. A method is then described for inserting the remaining branches into the graph to form a "pseudo planar graph". This represents a set of components and conductor paths which can be laid out on a single sided board without intersections. The number of conductor crossings is thus minimised before the actual layout commences. An algorithm is then described for automatically constructing a board layout from the pseudo planar graph. The relative interconnections are already known so the placement of components and routing of conductor paths can proceed simultaneously. The layout is therefore constructed in a series of logical steps working across from one edge of the board to the other. This approach contrasts with the more usual methods of layout in which components are placed first, followed by a search for conductor routes. The layout algorithm is also provided with facilities for man-machine interaction by means of a graphical display and light pen. Interaction allows the user to alter the positions of components during the construction of the layout. Thus the skill and experience of the user can be combined with the speed and accuracy of the automatic algorithm. Interaction also enables special conditions to be incorporated into the layout which would otherwise entail considerable programming effort. Three different circuits are used to test the layout algorithm. The results are shown for layouts constructed both automatically and by the use of interaction. One layout is also compared with a manually-produced layout of the same circuit. The results show that a feasible method has been developed for the layout of printed wiring boards by computer. Comparable results are produced in considerably less time than normal layout methods.

No description available.

We analyze the resolved stellar populations of the faint stellar system, Crater, based on deep optical imaging taken with the Advanced Camera for Surveys on the Hubble Space Telescope. Crater's color-magnitude diagram (CMD) extends similar to 4 mag below the oldest main-sequence (MS) turnoff. Structurally, we find that Crater has a half-light radius of similar to 20 pc and no evidence for tidal distortions. We model. Crater's CMD as a simple stellar population (SSP) and alternatively by solving for its full star formation history. In both cases, Crater is well. described by an SSP with an age of similar to 7.5 Gyr, a metallicity of [ M / H] similar to 1.65, a total stellar mass of M-star similar to 1e4 M-circle dot, and. a luminosity of M-V similar to - 5.3, located at a distance of d similar to 145 kpc, with modest uncertainties due to differences in the underlying stellar evolution models. We argue that the sparse sampling of stars above the turnoff and subgiant branch are likely to be 1.0-1.4 M-circle dot blue stragglers and their evolved descendants, as opposed to intermediate- age MS stars. We find that. Crater is an unusually young cluster given its location in the Galaxy's outer halo. We discuss scenarios for Crater's origin, including the possibility of being stripped from the SMC or the accretion from lower- mass dwarfs such as Leo I or Carina. Despite uncertainty over its progenitor system, Crater appears to have been incorporated into the Galaxy more recently than z similar to 1 (8 Gyr ago), providing an important new constraint on the accretion history of the Galaxy.

Code generation from UML is still very limited. Diagrams, which are usually used for code generation describes the static structure. These are mostly the class diagrams. One of the most useful and least used types of diagrams is behavioral diagrams. The reason for this is mainly a lack of support from the UML specification. The onset of version 2.0 has brought visible changes in this area. This thesis will focus only on activity diagrams and possibilities of code generation from them. One of them will be verified on a prototype tool that can generate skeleton of code in chosen language (e.g. Java, C + +, PHP ,...). Then it will be compared to alternative approaches and evaluated in terms of its advantages and disadvantages. As input is expected activity diagram created and exported by external CASE tool in XMI format. Architecture of tool will provide possibility of defining new modules. So the end user will be able to program another output language by the medium of given interface.

Call number: LD2668 .T4 1950 W4 / Master of Science

Previously published work on the development of the Pt-based superalloys for high temperature and special applications, as well as phase equilibria work, showed that there were problems and uncertainties with the available Pt-Al phase diagram. The aim of the current work was to make a comprehensive study of all relevant phases, and to clarify the phase boundaries of the phases: (Pt), Pt3Al (all temperature versions), Pt2Al (both phases), and Pt5Al3, by use of higher resolution SEM and XRD. A displacive transformation was confirmed for cubic Pt3Al to tetragonal Pt3Al and from high temperature Pt2Al to low temperature Pt2Al. The -phase was observed to be present, the phase reactions were confirmed and the eutectic composition was found. The Pt6Al21 phase was identified instead of Pt5Al21, and was deduced to be a different interpretation of the same phase, although the former had been described as a metastable phase. The phases and phase boundaries were found to generally agree with Massalski, and disagreed with Oya et al. ’s phase diagram

Many textbooks have diagrams illustrating astronomy concepts. However, research shows that sometimes learners struggle to obtain information illustrated in diagrams. This study investigated learners‘ ability to interpret diagrams illustrating phases of the Moon. Three constructs formed a theoretical framework used to design the study and interpret results: a theory associated with design and interpretation of diagrams, spatial ability theory which explains how people mentally manipulate objects in space, and the theory of models which proposes issues to take into consideration when using models (e.g. diagrams) in classrooms. I collected and processed data in three phases. In the first phase, I administered a diagnostic test to 75 learners, investigating their ideas about concepts associated with phases of the Moon. In addition, I administered six spatial ability tests to these learners, investigating their mastery of spatial ability skills needed to understand concepts associated with phases of the Moon. Results show that all the learners lacked background knowledge of these concepts. Furthermore, most of the learners lacked spatial ability skills needed to understand these concepts. I used these results to select 10 learners for participation in the third phase of the study. Five of these learners had high spatial ability skills while the other five had low spatial ability skills. During the second phase of the study, I analyzed 28 diagrams illustrating phases of the Moon to investigate the extent to which their composition (i) might enable learners to perceive all diagrammatic information, (ii) might enable learners to understand information for which the diagrams are intended, and (iii) complies with context of intended learners. Results show that only few diagrams were designed in a way that might hinder perception of information. However, most diagrams were designed in a way that might hinder understanding of intended information, and many did not comply with context of intended viewers. These results enabled me to select four diagrams having the fewest design problems to be used in the third phase of the study. In the third phase, I interviewed the ten learners selected during the first phase, to investigate their ability to interpret diagrams illustrating phases of the Moon. The learners were generally able to interpret aspects of diagrams which required the diagrams to be perceived in two-dimensional space. However, they struggled to interpret aspects of the diagrams which required perception and mental manipulation of the components of the Earth-Moon-Sun system in three-dimensional space. The high spatial-ability learners were better able to cope with tasks requiring mental manipulation of the Earth-Moon-Sun system in space than their low spatial ability counterparts. These results suggest the existence of a link between spatial ability and learners‘ interpretation of these diagrams. Teachers should be informed about these findings to help them understand how usage of the diagrams might hinder leaning. This information might help them use diagrams that have fewer design problems. Also, teacher trainers should be informed about these findings, to help them caution pre-service teachers about problems found in textbook diagrams. In addition, publishers should be informed about findings of this study to help them improve quality of diagrams in school textbooks. Furthermore, researchers should investigate strategies that can help learners (particularly those with low spatial ability skills) to better cope with aspects of diagrams which require mental manipulation of the Earth-Sun-Moon system in space. Keywords Astronomy, phases of the Moon, diagram design, diagram interpretation, spatial ability.

Investigações dos sistemas binários LiF-BiF3 e NaF-BiF3 foram realizadas com o objetivo de esclarecer o comportamento térmico e os equilíbrios de fase destes sistemas e das suas fases intermediárias, um requisito importante para a obtenção de cristais de alta qualidade. Amostras de toda a faixa de composições (0 a 100 mol% BiF3) de ambos os sistemas foram analisadas em ensaios de análise térmica diferencial (DTA) e termogravimetria (TG), e também de calorimetria exploratória diferencial (DSC). Algumas composições específicas foram selecionadas para difração de raios-X para complementação dos dados experimentais. Devido à grande vulnerabilidade do BiF3 à contaminação por oxigênio, sua volatilidade e propensão a danificar peças de metal quando aquecido, foi necessário determinar as condições ótimas para os ensaios de análise térmica antes de investigar os sistemas em si. As relações de fase no sistema LiF-BiF3 foram completamente elucidadas e um diagrama de fases foi proposto e avaliado teoricamente mediante o software comercial Factsage. O diagrama em si consiste em um sistema peritético simples, no qual o único composto interno, o LiBiF4 se decompõe em LiF mais uma fase líquida. O sistema NaF-BiF3 não pôde ser completamente elucidado, sendo que as relações de fase do lado pobre em NaF (> 50% BiF3) ainda não são conhecidas. No lado rico em NaF, entretanto, identificou-se a possível decomposição peritectóide do composto NaBiF4. Em ambos os sistemas, foram observadas estruturas cristalográficas discrepantes daquelas da literatura para os compostos mistos, LiBiF4 , NaBiF4 e uma solução sólida de NaF e BiF3 chamada de fase I. As estruturas observadas experimentalmente permanecem desconhecidas e explicações para as discrepâncias foram propostas. / Investigations of the binary systems LiF-BiF3 and NaF-BiF3 were performed with the objective of clarifying the thermal behavior and phase equilibria of these systems and their intermediary phases, an important requisite for high-quality crystal growth. Several samples in the entire range of compositions (0 to 100 mol% BiF3) of both systems were subjected to experiments of differential thermal analysis (DTA) and thermogravimetry (TG), and also of differential scanning calorimetry (DSC). A few specific compositions were selected for X-ray diffraction to supplement the experimental data. Due to the high vulnerability of BiF3 to oxygen contamination, its volatility and propensity to destroy metal parts upon heating, it was necessary to determine the optimal conditions for thermal analysis before investigating the systems themselves. Phase relations in the system LiF-BiF3 were completely clarified and a phase diagram was calculated and evaluated via the commercial software Factsage. The diagram itself consists in a simple peritectic system in which the only intermediary compound, LiBiF4, decomposes into LiF and a liquid phase. The NaF-BiF3 system could not be completely elucidated and the phase relations in the NaF poor side (> 50% BiF3) are still unknown. In the NaF rich side, however, the possible peritectoid decomposition of the compound NaBiF4 was identified. In both systems X-ray diffraction yielded crystal structures discrepant with the literature for the intermediary phases, LiBiF4, NaBiF4 and a solid solution of NaF and BiF3 called I. The observed structures remain unknown and explanations for the discrepancies were proposed.

本論文包括對 Jaynes-Cummings-Hubbard (JCH) 系統的研究。在這個系統中，每個耦合光學腔之內都放置了一顆雙態原子，偶極相互作用導致系統有激發光子和原子的自由度。對量子電動力學系統的研究，使我們對光子與原子間的相互作用以及量子相變有更深的認識。 / 我們研究了一維JCH系統中有兩個激發子的本徵態。我們發現當真空拉比頻率與腔間穿隧率之比超過某一臨界值，兩個激發子的束縛態就會出現。 / 我們還為兩個腔的JCH系統之演化作出研究，並指出系統的量子態在一定條件下可演變成薛丁格貓態。從相干態演化到薛丁格貓態所需的時間亦被估計。 / 最後，我們使用主方程來探討驅動JCH系統的去相干。在這篇論文中，我們提出了一些低激發量的穩態的例子。許多不同的穩態系統的光子統計將被討論。 / This thesis comprises of an investigation of the Jaynes-Cummings-Hubbard (JCH) system. In such a system, single two-level atoms are embedded in each coupled optical cavity, and the dipole interaction leads to dynamics involving photonic and atomic degrees of freedom. The investigation of quantum electrodynamics in the system provides insight about the behaviour of strongly interacting photons and atoms and quantum phase transition. / We examine the eigenstates of the one-dimensional JCH system in the two-excitation subspace. We discover that two-excitation bound states emerge when the ratio of vacuum Rabi frequency to the tunnelling rate between cavities exceeds a critical value. / We also study for the time evolution of a two-cavity JCH system, and indicate that the evolved state can be a Schrödinger's cat state under certain conditions. The time required for evolving a coherent state into a Schrödinger's cat state is also estimated. / Finally, we investigate the decoherence of a driven JCH system by using the master equation. In this thesis we present several examples of steady state when the total number of excitation is low. The photon statistics of the steady state of the system will be discussed. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wong, Tsz Ching Max = Jaynes-Cummings-Hubbard模型的課題 / 黃子澄. / "November 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 79-84). / Abstracts also in Chinese. / Wong, Tsz Ching Max = Jaynes-Cummings-Hubbard mo xing de ke ti / Huang Zicheng. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Basic Description of the Jaynes-Cummings-Hubbard Model --- p.4 / Chapter 2.1 --- Jaynes-Cummings Model --- p.4 / Chapter 2.1.1 --- Hamiltonian --- p.5 / Chapter 2.1.2 --- Energy Eigenstates --- p.6 / Chapter 2.2 --- Coupled-cavity System without Atoms --- p.8 / Chapter 2.2.1 --- A One-dimensional Coupled-cavity Chain --- p.8 / Chapter 2.2.2 --- Normal Modes --- p.9 / Chapter 2.3 --- Jaynes-Cummings-Hubbard Model --- p.10 / Chapter 2.3.1 --- Eigenstates of Single Excitation --- p.11 / Chapter 2.3.2 --- Dynamics of Single Excitation --- p.12 / Chapter 2.3.3 --- Single Excitation in the Weak Coupling Limit --- p.15 / Chapter 2.3.4 --- Single Excitation in the Strong Coupling Limit --- p.16 / Chapter 3 --- Solution of the JCH Model with Two Excitations --- p.17 / Chapter 3.1 --- Two-particle Bound States in the Bose-Hubbard Model --- p.17 / Chapter 3.2 --- Two-polariton Bound States in the JCH Model --- p.19 / Chapter 3.2.1 --- Bound State Eigenvectors --- p.24 / Chapter 3.2.2 --- Bound State Eigenvalues --- p.26 / Chapter 3.2.3 --- Critical Coupling --- p.28 / Chapter 3.2.4 --- Analytic Approximations in Strong Coupling Regime n≫k --- p.30 / Chapter 3.3 --- Dynamics of Two Excitations in Strong Coupling Regime --- p.33 / Chapter 3.3.1 --- Initial Condition: --- p.33 / Chapter 3.3.2 --- Initial Condition: Superposition of j2; gin in Gaussian Distribution --- p.34 / Chapter 3.3.3 --- Initial Condition: Superposition of j1; gin j1; gim in Gaussian Distribution --- p.39 / Chapter 3.3.4 --- Initial Condition: Superposition of j1;+in j1; ¡im in Gaussian Distribution --- p.39 / Chapter 4 --- JCH Model in a Two-cavity Con¯guration --- p.41 / Chapter 4.1 --- Generation of SchrÄodinger's Cat State: Numerical Simulation --- p.41 / Chapter 4.2 --- Generation of SchrÄodinger's Cat States: Analytic Solution --- p.45 / Chapter 4.2.1 --- Estimation of Optimum Parameters --- p.53 / Chapter 4.3 --- Coherent States as Initial Conditions --- p.55 / Chapter 5 --- Decoherence of a Weakly Driven JCH Model --- p.60 / Chapter 5.1 --- Master Equation --- p.60 / Chapter 5.2 --- Driven JCH Model: N-cavity Configuration --- p.61 / Chapter 5.2.1 --- One-excitation Approximation --- p.63 / Chapter 5.2.2 --- Simple Harmonic Oscillator Limit --- p.66 / Chapter 5.3 --- Driven JCH Model: Two-cavity Configuration --- p.69 / Chapter 6 --- Conclusion --- p.76 / Bibliography --- p.79

"Timing diagrams are used in industrial practice as a specification language of circuit components. They have been formalized for efficient use in model checking. This formalization is often more succinct and convenient than the use of temporal logic. We explore the relationship between timing diagrams and temporal logic formulas by showing that closure under disjunction does not hold for timing diagrams. We give an algorithm that returns a disjunction (if any) of two given timing diagrams. We also give algorithms that decide satisfiability of a timing diagram and return exact time separations between events in a timing diagram. An Alloy specification for timing diagrams with one waveform has also been built."