11 |
Generation of Topological Interlocking Configurations from a Geometric ApproachAndres M Bejarano Posada (8770007) 28 April 2020 (has links)
A Topological Interlocking Configuration (TIC) is an assembly where the shape and alignment of the blocks define the kinematic constraints. Conventional TICs are single-layered structures made of convex blocks. The interface between the blocks in an assembly is face-to-face contact. The traditional convention disregards the use of joinery, adhesive, or other mechanisms that keep two pieces next to each other. However, TICs require a support structure that prevents the lateral strain of the blocks.<br><br>The generation process of a TIC starts with a surface tessellation that describes a geometric domain. Each tile in the tessellation represents a traversal section of a block. For regular tessellations and uniform generation parameters, such sections lie in the middle of their respective blocks. Additionally, such conditions guarantee the blocks align adequately with each other. If one of such conditions does not hold, then the resultant blocks may not be aligned. Furthermore, there could be overlapping between the blocks, which makes a TIC invalid.<br><br>Traditionally, the generation parameters are angle values set at the edges of the tiles. The angles must match between tiles such that each block in the assembly has a geometry that imposes kinematic constraints to its neighboring blocks. Using the same angle values on regular and semi-regular tessellation produces feasible blocks. That is not the case for non-regular tessellations, curvilinear surfaces, and free-form 3D meshes. In such cases, the generation method must find specific angle values to design the blocks and reduce overlapping.<br><br>In this thesis, we propose a TIC generation framework focused on the generation of valid interlocking assemblies based on multiple types of surface tessellations. We start with the Height-Bisection method, a TIC generation approach that uses the distances from a tile to its respective evolution sections as the generation parameters. The method considers the bisector vectors between two tiles to define the parameters that generate aligned blocks to each other. We expand the generation model to a complete pipeline process that finds feasible generation parameters. The pipeline includes clipping parameters and methods in case that overlapping between blocks cannot be avoided.<br><br>Additionally, we describe a generalization of the mid-section evolution concept to include multiple evolution steps during the generation process. Our approach considers the angles and distances required to generate infinitely many TICs, including shapes that are not possible using the traditional generation method and the Height-Bisection method. Finally, we consider the interlocking assemblies that cannot maintain static equilibrium due to the shape of the surface tessellation. We consider the Structure Feasibility Analysis method to find the location and magnitude of the minimum tension forces that guarantee a TIC will reach a static equilibrium state. We describe how to update the generation parameters according to the results of the feasibility analysis. Our results show that the proposed pipeline generates valid TICs based on different surface tessellations, including closed and free-form shapes.
|
12 |
Mechanics of Architectured TubesKyle Patrick Mahoney (11184507) 26 July 2021 (has links)
<div>Architectured material systems offer the ability to control a system's response through the spatial arrangement of material. Material may be connected by discrete linkages or segmented by discrete cuts in such a system. This thesis serves as an investigation of the deformation and load response of architectured material systems in tubular configurations. Specifically, segmented tubes composed of interlocking building blocks and corrugated tubes formed from thin sheets of material are of interest.</div><div> </div><div>Interlocking, segmented tubes, or topologically interlocking material (TIM) tubes, are considered as assemblies of convex polyhedra. Multiple aspect ratios of tubes are considered with identical building block size. The load response to diametral indentation is obtained by finite element analysis and experimentation on additively manufactured tubes. Finite element models consider both an idealized scenario, where contacts between building blocks are stiff, and a realistic scenario, where there are much softer contacts between building blocks and a limit on shear stresses due to friction at contact interfaces. The mechanics of the deformation of TIM tubes are quantified by stress distributions and energies obtained from finite element models. It was found that interlocking between building blocks grants segmented systems increased stiffness, strength, and toughness. The response of TIM tubes varied with tube aspect ratio and contact conditions between blocks. An analysis of thrust-lines in the assembly with finite element results led to the formulation of a model to predict the load response of interlocking, segmented tubes. This model was found to fit idealized FE-model results, and, with the addition of slip between building blocks to the model, experiment results.</div><div> </div><div>Corrugated tubes are considered to be formed from stacks of sheet metal plies. Corrugations are formed one-by-one with a high-pressure fluid and forming machinery. The manufacturing process of these tubes is recreated in a finite element model. With this manufacturing model, the as-formed geometry and residual stress and strain profile of the tube are obtained. Finite element models of corrugated tube loading are created such that their initial state is the result of the manufacturing model. The response of corrugated tubes can then be investigated under the consideration of effects from manufacturing. Including the effects from manufacturing was found to influence the corrugated tube stiffness and yield force. Altering the ply thickness used to form tubes was also found to influence the corrugated tube stiffness. Certain fatigue failure locations were only predicted when including the effects from manufacturing in finite element simulations. Thus, the effects from manufacturing a corrugated tube were found to play a significant role in the tube's load response and failure.</div>
|
13 |
Seismic Design Manual for Interlocking Compressed Earth BlocksKennedy, Nicholas Edwards 01 June 2013 (has links) (PDF)
Seismic Design Manual for Interlocking Compressed Earth Blocks
Nicholas Edwards Kennedy
This thesis presents a comprehensive seismic design manual to be used to design and construct simple Interlocking Compressed Earth Block (ICEB) structures in seismically active regions. ICEBs are earth blocks made primarily of soil and stabilized with cement. They have female and male stud mechanisms designed to interlock when stacked, eliminating the need for mortar. The blocks can accept reinforcement and grout after they are placed. While ICEB construction is similar to conventional masonry construction, current design code standards for masonry only partially capture the actual behavior of ICEB structures. This thesis seeks to supplement the existing masonry design procedures and tailor them for use with ICEBs.
Additionally, this paper presents a preliminary design of ICEB shear walls for a disaster reconstruction project in the Philippines. While many structures in Southeast Asia and the Malay Archipelago are constructed from earthen blocks, very few are engineered. Of those that are, a lack of formal design guidance specific to ICEB construction leaves most engineers and designers with conventional concrete masonry design practices, some of which are not applicable for use with ICEBs.
|
14 |
Selecting Variability in Interlocking Behavioral ContingenciesUrbina, Tomas, III 12 1900 (has links)
The current study explored how the variability or lack thereof in interlocking behavioral contingencies (IBC) may be brought under contextual control. Four undergraduates (two dyads) students participated in the current study. Dyads were instructed to play a game on a computer screen with the goal to earn as many "Congratulations" as possible. An ABABAB reversal design was used. A Lag 1 schedule of cultural consequence delivery for IBC topography was set in the variability (VAR) condition. During the repeated (REP) condition only one IBC topography was reinforced. For one of the two dyads, the variability of IBC topography was brought under contextual control. It is important to explore the behavioral processes at the cultural level to understand prediction and control of cultural phenomena.
|
15 |
EVALUATION OF INTERLOCKING CONCRETE BLOCK PAVEMENT WITH RECYCLED MATERIALS BASED ON EXPERIMENTAL AND FINITE ELEMENT ANALYSISNi, Xinyue 11 1900 (has links)
To address the challenges associated with urban expansion and environmental changes, innovative interlocking concrete block pavement (ICBP) is being researched for usage in urban areas. The ICBP is designed to have higher durability and better long-term performance compared to traditional asphalt pavement. Using recycled concrete aggregates (RCA) and supplementary cementing materials (SCMs) can provide many environmental benefits. The objective of this research is to investigate the mechanical properties of concrete with recycled materials. This also involves the assessment of deflection and stresses associated with ICBP using the finite element method.
Four concrete mixtures with different RCA and SCMs contents were designed and cast. The RCA replacement levels were 20% and 40%, while slag and glass pozzolan were added to improve mechanical properties. The results showed that the use of RCA had adverse impacts on workability. The 28 days compressive strength of the Control Mix was 40 MPa. The compressive strength of Mix 3 was 40.5 MPa which was the highest strength among all mixtures. It demonstrated that a 40% RCA replacement level could have a non-negative effect on mechanical properties when the SCMs are added.
A three-dimensional pavement model was established using ABAQUS software. The orthogonal experimental design was used to evaluate the effects of the length/width ratio of blocks, the block thickness, the elastic modulus, and the laying pattern of blocks on the deflection and von Mises stress of all ICBP models under the vertical load. Considering the deflection of the loading area, the length/width ratio had the greatest effect, then comes with thickness, elastic modulus, and laying pattern according to the Range Analysis. The bigger block size and higher elastic modulus of blocks could provide even better performance. Overall, the herringbone laying pattern is recommended as the optimum laying pattern with minimum deflection. It also contributes to better load spreading. / Thesis / Master of Applied Science (MASc)
|
16 |
The Real "Syriana": Interlocking Directorates Shaping a Defense-Petroleum-Policy ComplexHaija, Rammy M. 24 April 2009 (has links)
Corporate interlocks between U.S. firms are a long-studied issue, and the apparent influence of these interlocks can be examined by applying theories of capitalism vs. the state arguments in examining the actual policy power that these interlocks potentially wield. This study investigates the link between corporate executives of the United States petroleum and military-defense industries, and examines the implications of the interlocking directorates that exist between these two industries, along with the strength of ties to government through former lawmakers and bureaucrats seated on these boards. The purpose of this research is to uncover evidence as to whether these interlocks and social network-ties are being utilized to further mutual interests of both these industries, along with the state, notably U.S.-led or U.S.-financed military or covert actions in petroleum-rich regions across the globe. The analysis reveals that interlocking directorates between the petroleum and defense industries show a high frequency of interlocks relative to other industries, along with a strong connection to government. This study points to the potential that oil-rich regions may have undergone U.S. military and covert interventions in an effort to not only gain access to petroleum, but to further the economic interests of the petroleum and defense industries. These findings lead to the conclusion that a real "Syriana," as in the plot of the 2005 film, may have been executed on two primary occasions during the George W. Bush administration. / Ph. D.
|
17 |
The corporate network of interlocking directorates, corporate governance, and firm performance in China's transitional economy. / CUHK electronic theses & dissertations collection / Digital dissertation consortiumJanuary 2005 (has links)
China has been undergoing economic reform and institutional transition from a planned economy to a market economy in the past twenty years. An important product of this is the emergence of interlocking directorates, a director who sit on multiple directorate boards of corporations. The formation of interlock network reflects the ongoing changes at economic, social and corporate levels. Its functioning mechanisms are also embedded within China's unique institutional environments. Given this background, this dissertation seeks to examine the corporate network of directorship interlocks in China, specifically with regard to the following three research questions. First, what is the corporate interlock network structure? Second, why do firms form directorship interlocks? And third, how does directorship interlock influence firm performance? / Cross-sectional data from 949 listed firms in 1999 and panel data from 284 listed firms spanning eight years (1994-2001) were employed to examine the interlock network structure and test the propositions. The results show that, first, directorship interlock network reflects the key structural features of Chinese economy. Second, the formation of interlocks reflects the inter-organizational demand and the demand of external interest group coalitions. Third, due to governance failure and institutional voids, interlock network acts as a social cohesion device and enables the emerging managerial class to exploit modern corporations to the detriment of shareholders' interests. This exploitation has dampened firm performance and economic growth. Such exploitation is constrained under concentrated ownership structure and under the ownership structure with high level of state ownership. / The dissertation contributes to the current literature in the following ways. First, it reports the first examination of the structural aspect of Chinese economy. Second, borrowing the conventional wisdom in directorship interlock literature, the dissertation incorporates China's unique institutional environments in examining the antecedents and consequences of directorship interlock, transcending the narrow theoretical synthesis of current interlock studies. Third, it highlights the complex "agency problem" that has emerged during the process of China's economic development---"managerial class exploitation." Fourth, it highlights the important role of a concentrated ownership structure and state ownership in constraining and facilitating the "managerial class exploitation". The dissertation provides significant insights in the fields of transitional economy, corporate governance, and directorship interlock network. / The dissertation makes four major propositions. First, the corporate network of interlocking directorates reflects key structural aspects of the Chinese economy. Second, directorship interlock may act as a strategy helping corporations to manage inter-organizational relationships and environmental uncertainty during the institutional transition. It may also act as a device for external interest groups to counterbalance the internal corporate power and exercise their control. Third, directorship interlock may perform two functions with opposing effect on firm performance. One is to act as an inter-organizational strategy to fill the institutional voids and enhance firm performance when the market fails. The other is to act as a social cohesion device to exploit institutional voids, facilitate managerial class exploitation, and dampen firm performance when governance fails. Fourth, ownership structure is an important factor in moderating directorship interlock network effects on firm performance during the institutional transition. / Ren Bing. / "August 2005." / Adviser: Kevin Au. / Source: Dissertation Abstracts International, Volume: 67-07, Section: A, page: 2653. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 265-280). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
|
18 |
Ensaios em board interlockingBarros, Thiago de Sousa 19 December 2017 (has links)
Submitted by Thiago Barros (tsousabarros@gmail.com) on 2018-01-11T18:18:37Z
No. of bitstreams: 1
Thiago Barros (2017) - Ensaios em Board Interlocking FGV.pdf: 2697775 bytes, checksum: 179d17770e8ab784fd42265ac0ed1779 (MD5) / Approved for entry into archive by Maria Tereza Fernandes Conselmo (maria.conselmo@fgv.br) on 2018-01-11T20:05:19Z (GMT) No. of bitstreams: 1
Thiago Barros (2017) - Ensaios em Board Interlocking FGV.pdf: 2697775 bytes, checksum: 179d17770e8ab784fd42265ac0ed1779 (MD5) / Made available in DSpace on 2018-01-12T16:19:07Z (GMT). No. of bitstreams: 1
Thiago Barros (2017) - Ensaios em Board Interlocking FGV.pdf: 2697775 bytes, checksum: 179d17770e8ab784fd42265ac0ed1779 (MD5)
Previous issue date: 2017-12-19 / Nos últimos anos, o tema da governança ganhou relevância no contexto corporativo, muito em função da proliferação de empresas multinacionais, do desenvolvimento dos mercados de capitais e do crescente número de investidores. Neste cenário, os Conselhos de Administração das firmas, figuras centrais para o cumprimento das funções de monitoramento, exercício das boas práticas de governança e proteção dos acionistas, vêm sendo estudados tanto no meio empresarial, quanto na esfera acadêmica. Tendo em consideração que a forma, o perfil e a independência do Conselho de Administração podem afetar as decisões tomadas pelas companhias, especialmente quanto as questões financeiras de investimento, além de impactar no desempenho das firmas e possibilitar a elas maior ou menor acesso a informações e recursos, esta tese almejou investigar o board interlocking – que é quando um conselheiro ocupa assento em mais de uma empresa –, característica usualmente notada nos mercados globais. Todavia, na literatura financeira contemporânea tem havido evidências empíricas antagônicas quanto aos reais benefícios e prejuízos advindos do uso dessa estratégia de deter Conselhos de Administração interligados, seja através de conselheiros compartilhados ou via interlocking político. Em face desses resultados discrepantes observados e para cumprir com os objetivos de pesquisa delineados, três ensaios foram desenvolvidos e integram este trabalho. O primeiro, utilizando uma amostra com 153 empresas brasileiras para a série 2000-2015, associa a temática do board interlocking com as operações de fusões e aquisições, uma vez que este pode ser um meio utilizado para reduzir assimetria informacional e custos de coleta, afetando a participação em M&As. Em adição e por meio de uma amostra de 174 firmas brasileiras, o segundo ensaio – observando que dentro de uma rede de empresas podem ocorrer formações de mundos pequenos (Small Worlds), grupos estes em que a informação circularia ainda de forma mais célere entre seus membros – investigou a existência desses Small Worlds na rede de firmas brasileiras, considerando o período 2000-2015, e sua influência nos processos de fusões e aquisições. Por fim, o terceiro ensaio, tendo por base uma amostra de companhias brasileiras e contemplando na análise os quatro últimos pleitos eleitorais ocorridos no Brasil (2002, 2006, 2010 e 2014), focalizou a relação entre interlocking político, medido através de doações de campanhas eleitorais e conselheiros com background político, e as previsões dos analistas, utilizando como proxy o custo de capital implícito. Os resultados do primeiro ensaio sugerem que firmas com maior degree, isto é, companhias que mantêm maior número de laços com outras, por meio de conselhos interligados, têm maior probabilidade de realizar fusões e aquisições. O segundo ensaio possibilita inferir que há formação de Small World nas redes anuais de empresas, dado o alto coeficiente de agrupamento e a baixa distância média entre as firmas. Contudo, os resultados sinalizam que o mundo pequeno não afeta significativamente a concretização de M&As, levando em consideração as fusões e aquisições no âmbito nacional e internacional. Por último, o terceiro ensaio evidencia que as doações para campanhas eleitorais, no cenário brasileiro, podem gerar efeitos negativos e os analistas de mercado avaliarem esse tipo de interlocking político como algo de maior risco, o que ocasiona, por conseguinte, maior custo de capital implícito para as empresas. Em contrapartida, deter no board conselheiros com background político não demonstrou relação significante, com exceção do período de Crise Fiscal (medido pela dummy PIB negativo e que compreendeu o hiato temporal 2014- 2015), quando os analistas precificaram o background político como algo negativo, elevando, portanto, o custo de capital implícito. / Governance has become a relevant topic within the corporate context in recent years, largely because of the proliferation of multinational companies, the development of capital markets and the growing number of investors. In this scenario, company Boards of Directors, which are central figures when it comes to complying with monitoring functions, exercising good governance practices and protecting shareholders, have been the object of study in both the business environment and the academic sphere. The shape, profile and independence of the Board of Directors can affect the decisions that companies take, especially with regard to financial investment issues. Such aspects can also have an impact on company performance and enable firms to have greater or lesser access to information and resources. The aim of this thesis, therefore, is to investigate board interlocking, a situation in which a director has a seat on the boards of more than one company, a characteristic normally seen in global markets. Some of the empirical evidence in contemporary financial literature, however, is antagonistic as far as concerns the real benefits and losses arising from the use of this strategy of having interconnected Boards of Directors, either by way of shared directors, or political interlocking. In view of these discrepant results and to comply with the research objectives that were outlined, three tests were developed and form part of this work. The first one, using a sample of 153 Brazilian companies for the 2000-2015 series, associates board interlocking with mergers and acquisitions, since this can be a way of reducing information asymmetry and collection costs, thus affecting participation in M&As. Small World formations may occur within a network of companies; these are groups in which information circulates even faster among members. The second test, therefore, involved a sample of 174 Brazilian firms and investigated the existence of these Small Worlds in the network of Brazilian firms, considering the period 2000-2015, and the influence of these Small Worlds on merger and acquisition processes. Finally, the third test, based on a sample of Brazilian companies and considering the last four presidential elections in Brazil (2002, 2006, 2010 and 2014), focused on the relationship between political interlocking, as measured by election campaign donations and directors with a political background, and the forecasts of analysts, using as a proxy the implicit cost of capital. The results of the first test suggest that firms with a higher degree, in other words, companies that have a greater number of ties with others by way of interconnected boards are more likely to become involved in mergers and acquisitions. The second test makes it possible to infer that Small Worlds are formed in annual company networks, given the high clustering coefficient and small average distance between firms. Taking into consideration both Brazilian and international mergers and acquisitions, the results, however, indicate that a Small World does not have a significant effect on the carrying out of M&As. Finally, the third test shows that donations to electoral campaigns in the Brazilian context can generate negative effects. Market analysts consider that there is greater risk with this type of political interlocking, which consequently leads to a higher implied cost of capital for the companies. On the other hand, having board members with a political background did not prove to have a significant relationship, except during the fiscal crisis period (as measured by the negative GDP dummy and which included the 2014-2015 hiatus) when analysts "priced" political background as being a negative factor, thus raising the implicit cost of capital.
|
19 |
The Lima occupation in the Lurin valley: towards the origins of monumental Pachacamac / La ocupación lima en el valle de Lurín: en los orígenes de Pachacamac monumentalMakowski, Krzysztof, Vallenas, Alain 10 April 2018 (has links)
The recent excavations of two important areas of the Pachacamac Monumental Sector, the foot of the principal facade of the Old Temple and the area beneath the hall of the main entrance at the Temple of the Sun, have allowed the authors to determine the relative chronology of the first construction at this site during the Early Intermediate Period. The ceramic fragments recovered share similar technological, formal and iconographic characteristics with the Lima Medio ceramics (Lima 4-5 in the Patterson sequence) from Chancay, Chillon and Ancon. This paper concurs with the hypothesis that after the conquest of the lower Rimac and Lurin valleys, there was an emerging regional multi-valley political entity which could relate to a complex chiefdom or an “Andean State.” However, during the Lima occupation of the Pachacamac site there is no evidence of an administrative center with urban residential zones. Instead, Pachacamac seems to have been a low-ranked local ceremonial center compared with the sites of Maranga, Pucllana or Cajamarquilla. / Las excavaciones llevadas a cabo por los autores en dos lugares claves del complejo monumental de Pachacamac, al pie de la fachada sur del Templo Viejo y debajo del vestíbulo de la entrada principal al Templo del Sol, han permitidodeterminar con precisión, la cronología relativa del inicio de obras de construcción, emprendidas durante el Periodo Intermedio Temprano, en el área del famoso santuario, ubicado sobre la margen izquierda del río Lurín, en los suburbios de Lima. El material cerámico asociado a los niveles de ocupación tiene las mismas características tecnológicas, formales e iconográficas que la cerámica Lima Medio (Lima 4-5 según Patterson (2014[1966]) en los valles de Chancay y Chillón, así como en Ancón. Cambios simultáneos, profundos, y de gran escala, se hacen presentes durante las fases Lima Medio en la Costa Central del Perú. Las tecnologías de producción de cerámica, su decoración, las técnicas de construcción, las formas de arquitectura, y los rituales funerarios, originarios de la cuenca de Chillón y de Ancón fueron adoptadas por laspoblaciones de Rímac y Lurín. Estas evidencias hacen reforzar la hipótesis que luego de la conquista de los valles bajos de Rímac y Lurín se está formando una entidad política regional multivalle con características de jefatura compleja y/o del «estado andino». Pachacamac lima no tuvo características de un centro administrativo con zonas urbanas residenciales, sino más bien las de un centro ceremonial local, posiblemente de rango subalterno, a juzgar por la comparación con Maranga, Pucllana y Cajamarquilla.
|
20 |
The Value of Ties: Impact of Director Interlocks on Acquisition Premium and Post-acquisition PerformanceLawani, Uyi 05 1900 (has links)
Mergers and acquisitions (M&A) evolved as alternative governance structures for firms seeking to combine resources with other firms, access larger markets, or acquire strategic assets. In spite of managers’ enthusiasm about the practice, studies show mixed results regarding post-acquisition performance of acquiring firms. The impact of acquisitions on the performance of acquiring firms has therefore remained inconclusive. A few reasons for this have been suggested and recent meta-analytic research efforts indicate that studies in M&A may have ignored variables that have significant effects on post-acquisition performance. In a bid to extend the literature on M&A and identify cogent variables that impact on acquisition performance, this dissertation draws on social network theory to advance a proposition for the value-of-ties. This was done by examining the impact of directorate interlocks on acquisitions specifically and organizational strategy in general. A non-experimental cross-sectional study of 98 interlocked directorate companies simultaneously involved in acquisitions was conducted. Several multiple regression analyses were conducted and the results obtained suggest that there is a positive linear relationship between director interlocks and post-acquisition performance and that to some extent this relationship is moderated by acquisition experience. The study also showed that director interlocks have a negative linear relationship with acquisition premium. This study complements the body of knowledge on acquisitions and network theory. It also successfully combined a multi-level approach to research on organizations and strategic management.
|
Page generated in 0.082 seconds