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Experimental analysis of the extension to shear fracture transition in Berea SandstoneBobich, Jennifer Kay 01 November 2005 (has links)
To characterize low-pressure, brittle deformation in porous, granular rock, notchcut
cylinders (30 mm neck diameter) of Berea Sandstone were extended in a triaxial
apparatus from 10 to 160 MPa confining pressure at strain rates of 10-4 s-1 and 10-5 s-1.
Acoustic emission counts were monitored when extending samples at a slow strain rate.
Stress at fracture is characterized by the least compressive principal stress, ??3, and
maximum compressive principal stress, ??1 (??1 = Pc). A change in strength dependence
on pressure at Pc = 50 MPa corresponds to a change from pure macroscopic extension
fracture to mixed-mode opening and shear fracture, and likely reflects the increase in
mean stress that suppresses the propagation of extension fractures and the interaction
between closely-spaced stepped cracks. Within the extension fracture regime (Pc < 50
MPa), ??3 at failure becomes slightly more tensile with an increase in Pc. At Pc > 50
MPa, ??3 at failure becomes more compressive with an increase in Pc and follows
Coulomb behavior; however, the angle between the fracture surface and ??1 increases
continuously with Pc. Fracture surfaces characteristic of the extension to shear fracture
transition appear as linked, stepped extension fractures; the length of extensional
segments decreases with increasing pressure. The onset of acoustic emissions and inelastic strain at fracture occurs at earlier points in the strain history with pressure,
consistent with the Griffith prediction of the beginning of fracture growth.
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A microstructural study of the extension-to-shear fracture transition in Carrara MarbleRodriguez, Erika 01 November 2005 (has links)
Triaxial extension experiments on Carrara Marble demonstrate that there is a
continuous transition from extension to shear fracture on the basis of mechanical
behavior, macroscopic fracture orientation and fracture morphology where hybrid
fractures with extension and shear fracture characteristics are formed at the intermediate
stress conditions. Extension fracture surfaces display discrete, highly reflective cleavage
planes and shear fracture surfaces are covered with calcite gouge and display grooves
and striations that are aligned parallel to slip. This study uses the fractured samples that
were formed under triaxial extension experiments to characterize 1) microscopic surface
features using scanning electron microscopy, 2) fracture surface morphology using laser
profilometry, and 3) off-fracture damage using optical microscopy. These data are used
to test the step-crack model of fracture development for the formation of hybrid fractures.
Spectral analysis of the profiles demonstrates that microscopic roughness
decreases gradually across the extension-to-shear fracture transition in both the
orientations parallel and perpendicular to slip. However, macroscopic roughness
gradually increases then decreases across the transition in the direction parallel to slip.
The greatest macroscopic roughness occurs at the transition from extension fractures to tensile-hybrid fractures and is attributed to the presence of macroscopic steps in hybrid
fractures surfaces. The treads of the steps in the hybrid fracture surfaces have
characteristics of extension fracture surfaces and the risers have characteristics of shear
fracture surfaces. The treads have a right-stepping left lateral geometry that is
consistent with the step-crack model. Thin sections of hybrid fractures display
systematically spaced, pinnate, microfractures that emanate from both sides of the
macroscopic fracture surface. The pinnate fractures on both sides correlate across the
macroscopic fracture, suggesting that they are precursory to the formation of the
macroscopic fracture surface. The spacing to length ratio of the pinnate fractures and the
macroscopic orientation of the fracture surface are also consistent the relationship
dictated by the step-crack model of fault formation.
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The rotavirus nonstructural protein 4 (NSP4) interacts with both the N- and C- termini of caveolin-1Mir, Kiran D 16 August 2006 (has links)
Rotavirus (RV) is an etiologic agent of viral gastroenteritis in children and infants
worldwide, accounting for an estimated 500,000 deaths annually. NSP4, the first
described viral enterotoxin, contributes to RV pathogenesis by mobilizing intracellular
calcium through multiple mechanisms that promote abnormal ion transport and
subsequent secretory diarrhea. NSP4 and the enterotoxic peptide 114-135 preferentially
interact with model membranes mimicking caveolae in lipid composition and radius of
curvature. Our laboratory has recently reported the colocalization and
coimmunoprecipitation of NSP4 with caveolin-1, the structural protein of caveolae.
Moreover, the caveolin-1 binding domain of NSP4 has been localized to the enterotoxic
peptide. We now report that caveolin-1 binds NSP4 via the N- and C-termini and one
terminus is sufficient for binding. A panel of caveolin-1 deletion mutants was expressed
in a yeast two-hybrid assay against an NSP4 bait. Caveolin-1 mutants retaining at least
one terminus were capable of binding the NSP4 bait. An in vitro binding assay
confirmed the two-hybrid results and localized the NSP4 binding domains to caveolin-1
residues 2-22 and 161-178. These data support the hypothesis that caveolin-1 mediates
NSP4 signaling and/or intracellular trafficking.
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A multi-exchange heuristic for formation of balanced disjoint ringsSasi Kumar, Sarath K 30 October 2006 (has links)
Telecommunication networks form an integral part of life. Avoiding failures on
these networks is always not possible. Designing network structures that survive these
failures have become important in ensuring the reliability of these network structures.
With the introduction of SONET (Synchronous Optical Network) technology, rings
have become the preferred survivable network structure. This network configuration
has a set of disjoint rings (each node being a part of single ring), and these disjoint
rings are connected via another main ring. In this research, we present a mathematical
model for the design of such disjoint rings with node number balance criterion
among the rings. When, given a set of nodes and distances between them, the Balanced
Disjoint Rings (BDR) problem is the minimum total link length clustering of
nodes into a given number of disjoint rings in such a way that there is almost the
same number of nodes in each ring. The BDR problem is a class of the standard
Traveling Salesman Problem (TSP). It is clear from this observation that the BDR
problem becomes a TSP when the number of rings required is set to one. Hence
BDR is NP-Hard, and we do not expect to obtain a polynomial time algorithm for
its solution. To overcome this problem, we developed a set of construction heuristics
(Break-MST, Distance Method, Hybrid Method, GRASP-Based Distance Method)
and improvement heuristics (Multi-Exchange, Single Move). Different combinations of construction and improvement heuristics were implemented and the quality of solution
thus obtained was compared to the standard Branch and Cut Technique. It was
found that the algorithm with GRASP-Based Distance Method as the construction
heuristic and multi-exchange - single-move combination as the improvement heuristic
performed better than other combinations. All combinations performed better in
general than the standard Branch and Cut technique in terms of solution time.
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Integrated high-resolution physical and comparative gene maps in horsesBrinkmeyer Langford, Candice Lea 25 April 2007 (has links)
High-resolution physically ordered gene maps for the horse (Equus caballus,
ECA) are essential to the identification of genes associated with hereditary diseases and
traits of interest like fertility, coat color, and disease resistance or susceptibility. Such
maps also serve as foundations for genome comparisons across species and form the
basis to study chromosome evolution. In this study seven equine chromosomes (ECA6,
7, 10, 15, 18, 21 and X) corresponding to human chromosomes (HSA) 2, 19 and X were
selected for high-resolution mapping on the basis of their potential involvement in
diseases and conditions of importance to horses. To accomplish this, gene- and
sequence-specific markers were generated and genotyped on the TAMU 5000rad horse x
hamster RH panel. Additionally, screening of a BAC library by overgoes and
subsequent STS content mapping and fingerprinting approaches were used to assemble
and verify a BAC contig along a ~5 Mb span on ECA21.
Dense gene maps were generated for each of the seven equine chromosomes by
adding 408 new markers (285 type I and 123 type II) to the current maps of these
chromosomes, thereby greatly improving overall map resolution to one mapped marker
every 960kb on average (range: 700 kb â 1.3 Mb). Moreover, the contig on ECA21 contained 47 markers (42 genes and 5 microsatellites) as well as 106 STS markers
distributed along 207 BAC clones. Comparisons of these maps with other species
revealed a remarkably high level of horse-human X chromosome conservation, as well
as two evolutionary breakpoints unique to Perissodactyls or Equids for the equine
homologues of HSA19 and HSA2, one of which has been more precisely localized by
the ECA21 contig. Thus, high resolution maps developed for these chromosomes i)
provide a basis to map traits of interest rapidly to specific chromosomal regions, ii)
facilitate searches for candidate genes for these traits by fine comparisons of the equine
regions with corresponding segments in other species, and iii) enable understanding the
evolution of the chromosomes. Expansion of this work to the entire equine genome will
be important for developing novel strategies for diagnosis, prevention, and treatment of
equine diseases.
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Mathematical modeling and analysis of a variable displacement hydraulic bent axis pump linked to high pressure and low pressure accumulators /Abuhaiba, Mohammad. January 2009 (has links)
Dissertation (Ph.D.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy degree in Mechanical Engineering." Bibliography: leaves 203-209.
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Effects of hybrid engine technology on Canadian light duty vehicle gasoline demand /Conn, Peter. January 1900 (has links)
Thesis (M.A.) - Carleton University, 2009. / Includes bibliographical references (p.68-71). Also available in electronic format on the Internet.
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A Performance Study of Hybrid Mobile Applications Compared to Native ApplicationsBrinkheden, Dan, Andersson, Robin January 2015 (has links)
This study evaluates the performance difference between hybrid and native mobile applica-tions when accessing the low level API. The purpose of this study is to find out the differ-ence in performance between the different methods for developing applications due to an increasing market for platform independent applications. Several benchmarks were created to measure the performance on the following criteria, execution time, memory allocation and storage space. The benchmarks were developed with a similar behaviour to match the functionality. The Titanium benchmarks were around 8.5 times larger in storage space and used 26-28% larger heap when it came to memory than the equivalent Android benchmarks. Android generally has a lower execution time than Titanium, however there are cases such as the math library where Titanium has a lower execution time.
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Hybrid systems : relationships between formal and informal communities in Caracas / Relationships between formal and informal communities in CaracasCruz Pifano, Jimena Laura 11 June 2012 (has links)
During the decade of 1950s, the intensive rural to urban migration, in search for new job opportunities, created a high housing demand that was partially solved by the dictatorial government of Marcos Perez Jimenez. However, in the absence of effective public policy and failed housing projects, the population started to create solutions of their own to satisfy their housing needs, settling themselves in an improvised way around the urbanized areas and constituting what we know today as informal settlements or barrios. By 1957, around 35% of the population of Caracas lived in barrios. During the past decade, Venezuela has experienced a series of changes that have modified the economic, political and social model that governed the country. During Chavez's government, there have been many policy changes regarding property, land, economic and social organization, in search for solutions to the housing problem that integrate the marginalized sector of the population. However, a different pattern of informal settlements has emerged. Some organized communities have started to invade not only vacant land in the city peripheries; they are now invading buildings that are inserted in the center of the city, contrasting to the formal systems already existing in the city. There is now a new interpretation of what is legal and what is not. We are experiencing the changes and understanding the consequences of their implementation. The purpose of this research is to understand the current processes of housing production and acquisition in formal and informal communities in Caracas through a review of existing literature and qualitative studies of the relationships between stakeholders. I analyze the new policies and the current housing production organization system and contrast it to what is actually happening in practice. I also investigated how incremental changes in existing practices can contribute to the development of safe and legible housing production processes. My recommendations are the result of hybrid systems that consider different actors and perspectives of the same reality in order to find a healthier and more sustainable building culture in Caracas. / text
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Staying online : a design for a sustainable community of practice for online instructorsAnderson, Michael William 26 November 2012 (has links)
The increasing demand for online and hybrid courses necessitates a corresponding increase in the number of higher education faculty members who offer instruction in these alternative delivery environments. Faculty members may resist course redesign due to concerns about increased workload and technology and require extrinsic motivation in the form of financial compensation and pedagogical and technological support as well as intrinsic motivation in the form of informal peer recognition, and intellectual satisfaction. Online courses offer temporal flexibility and multiple transactional axes but may superficially appear to devalue interaction. The apparent deindividuation of computer-mediated communication may be overcome by group socialization in collaborative communities which are focused on authentic problems. This report proposes a design-based research approach to determine the impact from an online collaborative community on the number of online course offerings and whether or not a professional development workshop that models interaction for participants will have a corresponding impact on the degree of interactivity incorporated in the respective courses of those faculty members. The proposal outlines the creation of a workshop offered in a hybrid delivery mode which through iterative instructional design interventions may lead to the development of a community of passionate instructors who collaborate to solve the technical and pedagogical challenges of their respective content disciplines and thereby meet the demand for online course offerings. / text
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