41 research outputs found
Incorporating shrinkage effects in FE modeling of prestressed concrete bridge
No full textRight from the inception of the implementation of prestressed concrete in the bridge construction field, it has been very popular. Even though this type of bridges has big advantages, cracking is a major problem. The cracking event, due to its detrimental effects on the structure is the most objectionable problem. In cracking shrinkage plays a very significant role. This implies that the study of shrinkage is essential to study the phenomenon of cracking. Due to many variables responsible for deck cracking, it is very difficult to study the overall effect of these variegated factors taken in the consideration at a time. This thesis aims to confluence as many such aspects as possible in a single plane of consideration with the help of Finite Element software namely ABAQUS. The goal of this research is to study shrinkage, shrinkage effects, and factors affecting the shrinkage and ultimately to incorporate the shrinkage effects in Finite Element Modeling. Here the study is constrained to Prestressed Concrete Bridge. Thus, the research is carried to incorporate the shrinkage effects in FE Modeling of Prestressed Concrete Bridge. This is a difficult task as many finite element programs do not have pre-programmed methods for simulating the time dependent properties of concrete. Therefore, it is necessary to develop these methods. This study concentrates on trying to simulate the behavior of a simple span bridge as a means of developing the basic analytical method. In the research Abaqus has been selected and the selection has been justified for the purpose of analyzing time dependent effects in bridges. A parametric study has been carried out with a view to identifying the effects of various parameters of shrinkage in a structure. The effects of the parameters such as length of the span, girder spacing, deck thickness and modulus of elasticity of girder have been analyzed with the help of bridges modeled in Abaqus. The parametric study concludes that shrinkage strain increases with increase in length and spacing of girder. The shrinkage strain decreases with increase in compressive strength of girder and deck thickness.M.S.Includes bibliographical referencesby Dhara Puran
Behavioral Subtyping in Object-Oriented Languages
No full textdata types, modules, packages; F.3.1 [Logics and Meanings of Programs] Specifying and Verifying and Reasoning about Programs --- logics of programs, pre- and post-conditions, theory A version of this technical report is published as the author's doctoral dissertation. c fl Copyright 1997 by Krishna Kishore Dhara All rights reserved. Department of Computer Science 226 Atanasoff Hall Iowa State University Ames, Iowa 50011-1040, USA ii TABLE OF CONTENTS 1. INTRODUCTION : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1 1.1 Problem : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 1.1.1 Reasoning problem and behavioral subtyping : : : : : : : : : : 2 1.1.2 Aliasing and behavioral subtyping : : : : : : : : : : : : : : : : 4 1.2 Overview of the solutions : : : : : : : : : : : : : : : : : : : : : : : : : 6 1.2.1 Different notions of behavioral subtyping : : : : : : : : : : : : 6 1.2.2 Semantic conditions : : : : : : : : : : : : : : : : : : : : : : : : 7 1.2.3 "..
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Quantum Communications with Near-Term Quantum Networks
No full textQuantum networks promise to enable provably secure communications, enhanced sensing, enhanced imaging and distributed quantum information processing. However, low generation rates and the quality of distributed entanglement will constrain near-term quantum networks. This dissertation explores near-term quantum networks for shared entanglement generation. We begin by reviewing the theoretical limits of quantum communications and the principles underlying quantum links and repeaters, including various photon-based and memory qubit encodings. We then analyze quantum link architectures for entanglement generation for a diverse class of photonic encodings. We subsequently analyze linear-chain quantum repeater networks; we discuss improvements to the rate-vs.-loss scaling with time-multiplexed entanglement swaps and the practical limitations associated with finite memory coherence times and buffer capacities. We propose satellite-assisted quantum links as an alternative to quantum repeaters, presenting and analyzing several candidate link architectures
Arterial flow based transfer function and ascending aorta pressure waveform estimation
No full textHypertension has been recognized as a leading cause of cardiovascular diseases. It is principally determined by the amount of the blood ejected by the heart and the properties of the receiving arteries. There is a strong correlation of a reduction in large artery compliance and high blood pressure. Thus, it is important to identify the causative factors that contribute to the severity of hypertension in terms of blood pressure, flow and mechanical properties of arteries. Numerous methods have been used to measure peripheral arterial blood pressure. As pressure waveform travels away from heart, it is amplified because of increased elastic stiffness which gives rise to wave reflections. As a result, peripheral pressure cannot accurately describe cardiovascular events. On the other hand, central aortic pressure is a much better predictor, but it can only be measured directly with an invasive catheter. For this reason, several pressure-based generalized transfer function methods have been proposed. In this thesis, a novel flow-based generalized transfer function is established. This new method is tested using carotid flow waveform as an input to predict ascending aortic flow. Additionally a three element windkessel model was used to predict ascending aortic pressure. Results show good correspondence of predicted ascending aortic flow and pressure. The present approach can be effectively applied in clinical situations where either peripheral arterial flow or ascending aortic flow noninvasively obtained by Doppler ultrasound can be used to obtain ascending aortic pressure. The derived aortic pressure waveform can then be further analyzed in terms of large artery compliance and systolic pressure augmentation, both critical in determining the severity of hypertension.M.S.Includes bibliographical referencesby Dhara Zal
Entangling Quantum Memories via Heralded Photonic Bell Measurement
No full textA common way to entangle quantum memories is via photonic entanglement swaps.
Each of two memories, connected by an optical channel, emits a photonic qubit
entangled with itself, and the photonic qubits undergo an entanglement swap on
a beamsplitter in the middle of the channel. We compare two choices of encoding
of the photonic qubit: single rail and dual rail. At low channel loss the
dual-rail scheme outperforms the single rail scheme. However, as expected, the
high-loss rate asymptote for the dual rail scheme scales quadratically worse
with loss compared with single rail. Considering the following non-idealities:
imperfect mode matching at the swap, carrier-phase mismatch across the
interfered photonic qubits, and detector excess noise, we evaluate the density
operator of the heralded two-qubit entangled state. We calculate a lower bound
on its distillable entanglement per copy, and its Fidelity (with the ideal Bell
state). For both schemes, imperfect swap-visibility results in a
constant-factor decrease in the rate, while excess noise results in a dropoff
of distillable entanglement beyond a certain total channel loss threshold, to
zero. Despite the single-rail scheme's better rate-loss scaling, it is more
severely affected by excess noise. The single-rail scheme is adversely affected
by stochastic carrier-phase mismatch, which does not affect the dual-rail
scheme. We study entanglement distillation on the heralded noisy entangled
states for both methods, and outline a suite of quantum networking studies that
our work could incite.Comment: 8 pages and 9 figures (main text); 4 appendices with 8 figures;
Comments are welcome
Developing E. coli-E. coli co-cultures to overcome barriers of heterologous tryptamine biosynthesis
No full textTryptamine is an alkaloid compound with demonstrated bioactivities and is also a precursor molecule to many important hormones and neurotransmitters. The high efficiency biosynthesis of tryptamine from inexpensive and renewable carbon substrates is of great research and application significance. In the present study, a tryptamine biosynthesis pathway was established in a metabolically engineered E. coli-E. coli co-culture. The upstream and downstream strains of the co-culture were dedicated to tryptophan provision and conversion totryptamine, respectively. The constructed co-culture was cultivated using either glucose or glycerol as carbon source for de novo production of tryptamine.The manipulation of the co-culture strains’ inoculation ratio was adapted to balance the biosynthetic strengths of the pathway modules for bioproduction optimization. Moreover, a biosensor-assisted cell selection strategy was adapted to improve the pathway intermediate tryptophan provision by the upstream strain, which further enhanced the tryptamine biosynthesis. The resulting biosensor-assisted modular co-culture produced 194mg/L tryptamine with a yield of 0.02 g/g glucose using shake flask cultivation.The findings of this work demonstrate that the biosensor-assisted modular co-culture engineering offers a new perspective for conducting microbial biosynthesis.Peer reviewe
Survey of the reptilian fauna of the Kingdom of Saudi Arabia: the Snake fauna of the central region
No full textCorresponding Author:
Mohammed K. Al-Sadoon
Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
Phone: +966-1-4675755
[email protected] snake fauna inhabiting the Central Region of the Kingdom of Saudi Arabia has been investigated by the collection and subsequent identification of211 specimens from various localities in the Reg-ion. Fourteen species belonging to five families: Boidae, Colubridae, Elapidae, Leptotyphlopidae and Viperidae were recorded. The following species were reported from the Central Region for the first time: Atractaspis microlepidota engaddensis, Leptotyphlops macrorhynchus, Spalerosophis diadem a cliffordi, Telescopus dhara dhara, Coluber ventromaculatus and Eryx jayakari. The geographical distribution of the snakes is presented together with notes on their habitats, and general biology
The self-catalytic and catalyst assisted CVD growth of high optical quality AlGaN nanowires
No full textExploring the possibility of a complex-valued non-Gaussianity measure for quantum states of light
No full textWe consider a quantity that is the differential relative entropy between a generic Wigner function and a Gaussian one. We prove that said quantity is minimized with respect to its Gaussian argument, if both Wigner functions in the argument of the Wigner differential entropy have the same first and second moments, i.e., if the Gaussian argument is the Gaussian associate of the other, generic Wigner function. Therefore, we introduce the differential relative entropy between any Wigner function and its Gaussian associate and we examine its potential as a non-Gaussianity measure. We prove that said quantity is faithful, invariant under Gaussian unitary operations, and find a sufficient condition on its monotonic behavior under Gaussian channels. We provide numerical results supporting aforesaid condition. The proposed, phase-space based non-Gaussianity measure is complex-valued, with its imaginary part possessing the physical meaning of the negative volume of the Wigner function. At the same time, the real part of this measure provides an extra layer of information, rendering the complex-valued quantity a measure of non-Gaussianity, instead of a quantity pertaining only to the negativity of the Wigner function. We examine the usefulness of our measure to non-Gaussian quantum state engineering with partial measurements
