53,678 research outputs found
Stability of front tracking solutions to the initial and boundary value problem for systems of conservation laws
No full textWe deal with the non characteristic initial and boundary value problem
for an strictly hyperbolic system of conservation laws in
one space dimension
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\partial_t u+ \partial_x F(u)=0,\qquad u(0,x) = \bar u (x)\,,\qquad
b\big( u(\psi(t),t) \big) = g(t)\,.\eqno (\ast)
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Here is a smooth vector field defined in an open, convex
neighborhood of the origin of , and are
functions with small total variation, is a non
characteristic Lipschitz boundary profile, and a
function. We prove that the front tracking solutions to ()
constructed by D. Amadori in \cite{Amadori} are stable for the
\elleuno topology. This implies the existence of a Standard Riemann
Semigroup and hence the well-posedness of ()
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Letter from C. D. Dawson, Tusayan Copper Mining and Smelting, to Carl Hayden
No full textLetter from C. D. Dawson to Carl Hayden urging him to consider the rights of miners and farmers when drawing up the boundaries for the proposed park
Flatness optimization of micro-injection moulded parts: the case of a PMMA microfluidic component
No full textMicro-injection moulding (µ-IM) has attracted a lot of interest because of its potential for the production of low-cost, miniaturized parts in high-volume. Applications of this technology are, amongst others, microfluidic components for lab-on-a-chip devices and micro-optical components. In both cases, the control of the part flatness is a key aspect to maintaining the component's functionality. The objective of this work is to determine the factors affecting the flatness of a polymer part manufactured by µ-IM and to control the manufacturing process with the aim of minimizing the in-process part deformation. As a case study, a PMMA microfluidic substrate with overall dimensions of 10 mm diameter and 1 mm thickness was investigated by designing a µ-IM experiment having flatness as the experimental response. The part flatness was measured using a micro-coordinate measuring machine. Finite elements analysis was also carried out to study the optimal ejection pin configuration. The results of this work show that the control of the µ-IM process conditions can improve the flatness of the polymer part up to about 15 µm. Part flatness as low as 4 µm can be achieved by modifying the design of the ejection system according to suggested guideline
Cultural and gender politics in a neglected archive of Jamaican women's poetry : Una Marson and her Creole contemporaries
No full textThis thesis considers the gender and cultural politics of selected Jamaican
women's poetry published during the first half of the twentieth century and
seeks to establish that an approach to this poetry sensitive to these issues will
illuminate aspects of their work previously neglected by canonical and colonial
modes of interpretation. The central interest of this thesis is the poetry of Una
Marson, a black woman poet whose work has been critically neglected and
devalued to date. My project is to read Marson's work in some detail, and to
explore to what extent her poetry, which often works within colonial models and
with conventional notions of feminine fulfilment, employs received aesthetic
and ideological paradigms both strategically and subversively. In the belief
that critics of Jamaican women's writing should be as attentive to the gender
and cultural politics of their ways of reading, as of the texts they wish to read,
the first chapter of this thesis engages in a sustained analysis of theoretical
positions and attempts to map out the various problems and possibilities
which critical discourses present in relation to this material. The second
chapter examines the various social and literary contexts in which Jamaican
poetry was produced and received during this period, and the third chapter
looks in more detail at contemporary notions of aesthetic and cultural forms.
The fourth and fifth chapters are structured aromd close textual readings
which explore the variety and complexity of Marson's, and her Creole
contemporaries', poetic engagement with the issues of cultural and gender
identities. The thesis concludes that Marson's poetry questions dominant
notions both of identity and of aesthetics, and consequently that her poetry
offers an example of Jamaican literary expression which moves beyond the
nationalization of consciousness which has come to mark the literary
achievement of this period
Measurement of the D+/- production asymmetry in 7 TeV pp collisions
No full textThe asymmetry in the production cross-section \sigma of D+/- mesons, A_P = (\sigma(D+) - \sigma(D-))/(\sigma(D+) + \sigma(D-)), is measured in bins of pseudorapidity \eta and transverse momentum p_T within the acceptance of the LHCb detector. The result is obtained with a sample of D+ -> K_S pi+ decays corresponding to an integrated luminosity of 1.0 fb^-1, collected in pp collisions at a centre of mass energy of 7 TeV at the Large Hadron Collider. When integrated over the kinematic range 2.0 K_S pi+ decay is negligible. No significant dependence on \eta or p_T is observed
D* (D)over-bar* molecule interpretation of Z(c)(4025)
No full textWe have used QCD sum rules to study the newly observed charged state Z(c)(4025) as a hidden-charm D*(D) over bar* molecular state with the quantum numbers I-G(J(P)) =1(+)(1(+)). Using a D*(D) over bar* molecular interpolating current, we have calculated the two-point correlation function and the spectral density up to dimension eight at leading order in alpha(s). The extracted mass is m(X) = (4.04 +/- 0.24) GeV. This result is compatible with the observed mass of Z(c)(4025) within the errors, which implies a possible molecule interpretation of this new resonance. We also predict the mass of the corresponding hidden-bottom B*(B) over bar* molecular state: m(Zb) = (9.98 +/- 0.21) GeV.Physics, Particles & FieldsSCI(E)[email protected]; [email protected]; [email protected]; [email protected]
Design 3D printing cementitious materials via Fuller Thompson theory and Marson-Percy model
No full textCementitious materials for 3D printing have special requirements for rheological properties, which are significantly affected by many factors, including sand gradation and packing fraction. Fuller Thompson theory and Marson-Percy model are classic approaches for sand gradation and packing fraction optimiza- tion, respectively. This paper attempts to apply Fuller Thompson theory and Marson-Percy model in designing cementitious materials for 3D Cementitious Materials Printing (3DCMP). Various gradation methods adopted in this study were Fuller Thompson gradation (mixture A), uniform-gradations (mix- ture B and C), gap-gradations (mixture D and E). Besides these mixtures with special gradation approaches, one mixture using natural river sand (mixture F) was prepared as well. Rheological proper- ties were characterized by static/dynamic yield stress and plastic viscosity in Bingham Plastic model. Buildability was examined by printing a column with 10 cm inner diameter via a gantry printer. Rheological test results indicate that mixture A designed by continuous gradation possesses the highest static/dynamic yield stress and lowest plastic viscosity. During printing test for buildability, mixture A can easily reach up to 40 layers without notable deformation, while all other mixtures deformed notice- ably and fell down before the 35th layer. Finally, a large-scale printing was carried out with mixture A and a structure with the height of 80 cm was printed successfully without notable deformation. Density, compressive strength and flexural strength of printed filaments were also characterized. Mechanical performance test results illustrate mixture A has the highest density and appropriate com- pressive strength, and a relative high flexural strength at different curing ages. These results indicate that Fuller Thompson theory and Marson-Percy model can serve as a reasonable guide for material rheology design for 3DCMP.NRF (Natl Research Foundation, S’pore)Accepted versio
Prompt charm production in pp collisions at √<span style="text-decoration:overline">s</span>=7 TeV
No full textCharm production at the LHC in pp collisions at s√=7 TeV is studied with the LHCb detector. The decays D0→K−π+, D+→K−π+π+, D⁎+→D0(K−π+)π+, D+s→ϕ(K−K+)π+, Λ+c→pK−π+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb−1. Differential cross-sections dσ/dpT are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0<pT<8 GeV/c and 2.0<y<4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above pT-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives
σ(cc¯)pT<8 GeV/c,2.0<y<4.5=1419±12(stat)±116(syst)±65(frag) μb,
where the uncertainties are statistical, systematic, and due to the fragmentation functions
Transport Equations and Multi-D Hyperbolic Conservation Laws
No full textThis book collects the lecture notes of two courses and one mini--course held in a winter school in Bologna in January 2005. The aim of this school was to popularize techniques of geometric measure theory among researchers and PhD students in hyperbolic differential equations. Though initially developed in the context of the calculus of variations, many of these techniques have proved to be quite powerful for the treatment of some hyperbolic problems. Obviously, this point of view can be reversed: the hope of the editors is that the topics of these notes will also capture the interest of some members of the elliptic community, willing to explore the links to the hyperbolic world.
The three contributions of the volume gravitate all around the theory of functions of bounded variation which play a fundamental role in the subject of hyperbolic conservation laws, and focus in particular on the structure and fine properties of BV functions in more than one space dimension
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