Modelling the behaviour of the bonding of fibre reinforced concrete at the plate end

Comunicação apresentada em International Symposium Polymers in Concrete (ISPIC 2006), Guimarães, 2006In this paper, the finite element method is used to analyse the behaviour of concrete externally strengthened by fibre reinforced polymers (FRP). This model aims to analyse the stress distribution in the FRP-concrete interface at the plate end of a bending beam. The behaviour of the concrete-poxy-FRP arrangement is modelled with interface elements with initial zero thickness, using a discrete crack approach. A localized damage model is adopted for the interface and a parametric study is performed to approximate the material parameters adopted. The importance of each parameter is assessed. This model is subsequently verified using experimental data collected from the literature. Finally, a proposal is made concerning the adoption of a relation GF II/GF for the interface behaviour. Mention is also made to some of the main mathematical models found in the literature, which are compared to the present approach

Recent Developments in the Design, Capabilities and Autonomous Operations of a Lightweight Surface Manipulation System and Test-bed

The first generation of a versatile high performance device for performing payload handling and assembly operations on planetary surfaces, the Lightweight Surface Manipulation System (LSMS), has been designed and built. Over the course of its development, conventional crane type payload handling configurations and operations have been successfully demonstrated and the range of motion, types of operations and the versatility greatly expanded. This enhanced set of 1st generation LSMS hardware is now serving as a laboratory test-bed allowing the continuing development of end effectors, operational techniques and remotely controlled and automated operations. This paper describes the most recent LSMS and test-bed development activities, that have focused on two major efforts. The first effort was to complete a preliminary design of the 2nd generation LSMS that has the capability for limited mobility and can reposition itself between lander decks, mobility chassis, and fixed base locations. A major portion of this effort involved conducting a study to establish the feasibility of, and define, the specifications for a lightweight cable-drive waist joint. The second effort was to continue expanding the versatility and autonomy of large planetary surface manipulators using the 1st generation LSMS as a test-bed. This has been accomplished by increasing manipulator capabilities and efficiencies through both design changes and tool and end effector development. A software development effort has expanded the operational capabilities of the LSMS test-bed to include; autonomous operations based on stored paths, use of a vision system for target acquisition and tracking, and remote command and control over a communications bridge

Tolerating the Community Detection Resolution Limit with Edge Weighting

Communities of vertices within a giant network such as the World-Wide Web are likely to be vastly smaller than the network itself. However, Fortunato and Barth\'{e}lemy have proved that modularity maximization algorithms for community detection may fail to resolve communities with fewer than $\sqrt{L/2}$ edges, where $L$ is the number of edges in the entire network. This resolution limit leads modularity maximization algorithms to have notoriously poor accuracy on many real networks. Fortunato and Barth\'{e}lemy's argument can be extended to networks with weighted edges as well, and we derive this corollary argument. We conclude that weighted modularity algorithms may fail to resolve communities with fewer than $\sqrt{W \epsilon/2}$ total edge weight, where $W$ is the total edge weight in the network and $\epsilon$ is the maximum weight of an inter-community edge. If $\epsilon$ is small, then small communities can be resolved. Given a weighted or unweighted network, we describe how to derive new edge weights in order to achieve a low $\epsilon$, we modify the ``CNM'' community detection algorithm to maximize weighted modularity, and show that the resulting algorithm has greatly improved accuracy. In experiments with an emerging community standard benchmark, we find that our simple CNM variant is competitive with the most accurate community detection methods yet proposed.Comment: revision with 8 pages 3 figures 2 table

Parallel Shortest Path Algorithms for Solving Large-Scale Instances

We present an experimental study of parallel algorithms for solving the single source shortest path problem with non-negative edge weights (NSSP) on large-scale graphs. We implement Meyer and Sander's Δ-stepping algorithm and report performance results on the Cray MTA-2, a multithreaded parallel architecture. The MTA-2 is a high-end shared memory system offering two unique features that aid the efficient implementation of irregular parallel graph algorithms: the ability to exploit fine-grained parallelism, and low-overhead synchronization primitives. Our implementation exhibits remarkable parallel speedup when compared with a competitive sequential algorithm, for low-diameter sparse graphs. For instance, Δ-stepping on a directed scale-free graph of 100 million vertices and 1 billion edges takes less than ten seconds on 40 processors of the MTA-2, with a relative speedup of close to 30. To our knowledge, these are the first performance results of a parallel NSSP problem on realistic graph instances in the order of billions of vertices and edges

Quantum Dot Version of Berry's Phase: Half-Integer Orbital Angular Momenta

We show that Berry's geometrical (topological) phase for circular quantum dots with an odd number of electrons is equal to \pi and that eigenvalues of the orbital angular momentum run over half-integer values. The non-zero value of the Berry's phase is provided by axial symmetry and two-dimensionality of the system. Its particular value (\pi) is fixed by the Pauli exclusion principle. Our conclusions agree with the experimental results of T. Schmidt {\it at el}, \PR B {\bf 51}, 5570 (1995), which can be considered as the first experimental evidence for the existence of a new realization of Berry's phase and half-integer values of the orbital angular momentum in a system of an odd number of electrons in circular quantum dots.Comment: 4 pages, 2 figure

C-type cytochrome-initiated reduction of bacterial lytic polysaccharide monooxygenases

The release of glucose from lignocellulosic waste for subsequent fermentation into biofuels holds promise for securing humankind's future energy needs. The discovery of a set of copper-dependent enzymes known as lytic polysaccharide monooxygenases (LPMOs) has galvanised new research in this area. LPMOs act by oxidatively introducing chain breaks into cellulose and other polysaccharides, boosting the ability of cellulases to act on the substrate. Although several proteins have been implicated as electron sources in fungal LPMO biochemistry, no equivalent bacterial LPMO electron donors have been previously identified, although the proteins Cbp2D and E from Cellvibrio japonicus have been implicated as potential candidates. Here we analyse a small c-type cytochrome (CjX183) present in Cellvibrio japonicus Cbp2D, and show that it can initiate bacterial CuII/I LPMO reduction and also activate LPMO-catalyzed cellulose-degradation. In the absence of cellulose, CjX183-driven reduction of the LPMO results in less H2O2 production from O2, and correspondingly less oxidative damage to the enzyme than when ascorbate is used as the reducing agent. Significantly, using CjX183 as the activator maintained similar cellulase boosting levels relative to the use of an equivalent amount of ascorbate. Our results therefore add further evidence to the impact that the choice of electron source can have on LPMO action. Furthermore, the study of Cbp2D and other similar proteins may yet reveal new insight into the redox processes governing polysaccharide degradation in bacteria

Evanescence in Coined Quantum Walks

In this paper we complete the analysis begun by two of the authors in a previous work on the discrete quantum walk on the line [J. Phys. A 36:8775-8795 (2003) quant-ph/0303105 ]. We obtain uniformly convergent asymptotics for the "exponential decay'' regions at the leading edges of the main peaks in the Schr{\"o}dinger (or wave-mechanics) picture. This calculation required us to generalise the method of stationary phase and we describe this extension in some detail, including self-contained proofs of all the technical lemmas required. We also rigorously establish the exact Feynman equivalence between the path-integral and wave-mechanics representations for this system using some techniques from the theory of special functions. Taken together with the previous work, we can now prove every theorem by both routes.Comment: 32 pages AMS LaTeX, 5 figures in .eps format. Rewritten in response to referee comments, including some additional references. v3: typos fixed in equations (131), (133) and (134). v5: published versio

The Vehicle, 1968, Vol. 10 no. 2

Vol. 10, No. 2 Table of Contents 1st Prize, ArtCorner of My MindGerry Moreheadpage 4 #1Clyde Simspage 5 Aesthetics for a VagabondByron Nelsonpage 5 1st Prize, Short StorySteam HeatCharles Whitepage 6 a drawingSally Roachpage 6 an untitled themeCatherine Waitepage 8 MoodKevin Sheapage 9 1st Prize, PoetryHome ThoughtsJane Careypage 10 an untitled poemCatherine Waitepage 11 a drawingSally Roachpage 11 GraceJames T. Jonespage 12 LonelinessSally Roachpage 14 Love, JimmyAstaire Pappaspage 14 CapturedJeff Nelsonpage 15 Winnie Davis Neely AwardUnconcernRoger Zulaufpage 17 an untitled poemDavid N. Deckerpage 17 Morality and American Foreign Policy: The Ever-widening GapBruce L. Berrypage 18 La LibertadChris Holavespage 19 1966Roger Zulaufpage 19 SinThomas W. Phippspage 20 a drawingRoger Perkinspage 20 Summer SweatJerry J. Carterpage 20 1st Prize, EssayCuriosityThomas W. Phippspage 21 A Bottle of DreamsMaurice Snivelypage 21 Chalk DustCatherine Waitepage 22 Diffused Existence or, a Meager Attempt at Helping You Over the Rough SpotsJan Gerlachpage 22 To *e.e.Paula Bresnanpage 22 A PoemThomas W. Phippspage 22 Beach PartyJerol Mikeworthpage 22 Wexford\u27s PartyRoy Lueckepage 23 The Four O\u27Clock ClubSally Roachpage 23 Chesterpage 24https://thekeep.eiu.edu/vehicle/1018/thumbnail.jp

UNICORN Babies: Understanding Circulating and Cerebral Creatine Levels of the Preterm Infant. An Observational Study Protocol

Creatine is an essential metabolite for brain function, with a fundamental role in cellular (ATP) energy homeostasis. It is hypothesized that preterm infants will become creatine deplete in the early postnatal period, due to premature delivery from a maternal source of creatine and a limited supply of creatine in newborn nutrition. This potential alteration to brain metabolism may contribute to, or compound, poor neurological outcomes in this high-risk population. Understanding Creatine for Neurological Health in Babies (UNICORN) is an observational study of circulating and cerebral creatine levels in preterm infants. We will recruit preterm infants at gestational ages 23+0–26+6, 27+0–29+6, 30+0–32+6, 33+0–36+6, and a term reference group at 39+0–40+6 weeks of gestation, with 20 infants in each gestational age group. At birth, a maternal capillary blood sample, as well as a venous cord blood sample, will be collected. For preterm infants, serial infant plasma (heel prick), urine, and nutrition samples [total parenteral nutrition (TPN), breast milk, or formula] will be collected between birth and term “due date.” Key fetomaternal information, including demographics, smoking status, and maternal diet, will also be collected. At term corrected postnatal age (CPA), each infant will undergo an MRI/1H-MRS scan to evaluate brain structure and measure cerebral creatine content. A general movements assessment (GMA) will also be conducted. At 3 months of CPA, infants will undergo a second GMA as well as further neurodevelopmental evaluation using the Developmental Assessment of Young Children – Second Edition (DAYC-2) assessment tool. The primary outcome measures for this study are cerebral creatine content at CPA and plasma and urine creatine and guanidinoacetate (creatine precursor) concentrations in the early postnatal period. We will also determine associations between (1) creatine levels at term CPA and neurodevelopmental outcomes (MRI, GMA, and DAY-C); (2) dietary creatine intake and circulating and cerebral creatine content; and (3) creatine levels and maternal characteristics. Novel approaches are needed to try and improve preterm-associated brain injury. Inclusion of creatine in preterm nutrition may better support ex utero brain development through improved cerebral cellular energy availability during a period of significant brain growth and development.Ethics Ref: HDEC 18/CEN/7 New Zealand.ACTRN: ACTRN12618000871246