Cumulene Molecular Wire Conductance from First Principles

We present first principles calculations of current-voltage characteristics (IVC) and conductance of Au(111):S2-cumulene-S2:Au(111) molecular wire junctions with realistic contacts. The transport properties are calculated using full self-consistent ab initio NEGF-DFT methods under external bias. The conductance of the cumulene wires shows oscillatory behavior depending on the number of carbon atoms (double bonds). Among all conjugated oligomers, we find that cumulene wires with odd number of carbon atoms yield the highest conductance with metallic-like ballistic transport behavior. The reason is the high density of states in broad LUMO levels spanning the Fermi level of the electrodes. The transmission spectrum and the conductance depend only weakly on applied bias, and the IVC is nearly linear over a bias region from +1 to -1 V. Cumulene wires are therefore potential candidates for metallic connections in nanoelectronic applications.Comment: Accepted in Phys. Rev. B; 5 pages and 6 figure

Top quark pair production via e+e−e^{+}e^{-} collision in the littlest Higgs model with T-parity at the ILC

In the littlest Higgs model with T-parity, we studied the contributions of the new particles to the top-quark pair production via $e^{+}e^{-}$ collision at the International Linear Collider. We calculated the top-quark pair production cross section and found this process can generate significantly relative correction. The result may be a sensitive probe of the littlest Higgs model with T-parity

Wind loads on Y plan shape tall building

An experimental study was carried out on the models of lsquoYrsquo plan shape tall building in an open circuit wind tunnel to investigate the wind loads generated on the building in isolated as well as interference condition. The base shear (Fx), overturning moment (My) and torsional moment (Mz) acting on the instrumented model were measured. For the isolated condition, the measurements were made for many wind incidence angles. For studying the interference effects, two similar building models were placed in side-by-side configuration and tandem configuration and the spacing between these models were varied. It is observed that the wind incidence angle greatly affects the wind induced loads on the lsquoYrsquo plan shaped building. Depending on the position of the interfering building, the interfence effects may either be beneficial or may have an adverse effect

A New Receiver for a Digital Passband System with CPSK Modulation: The STTS-CPSK Receiver

671-677Telecommunications industry is expanding vastly with huge infrastructure requiring huge sums of money for investment1,2. Reliability of the system3,4, efficient utilization of resources1,2, and safety of the users and the environment are paramount towards providing high quality efficient telecom services at affordable prices1,2. This paper deals with an important scientific investigation for the development of the STTS-CPSK receiver for pass band applications5,6 . This is a new receiver being developed with the inspiration from the previously developed STTS-MF receiver for baseband applications. This is carried out considering transmission of p-q signals (p-q signals represent correlated digital signals) through AWGN channel. Performance-comparison studies of the conventional STS-CPSK receiver and the new STTS-CPSK receiver are carried out for a wide range of signal and system parameters 0.0 ≤ p,q ≤ 1.0 and-10 dB ≤ SNR ≤ 10 dB. Performance superiority of the STTS-CPSK receiver is established for 0.0 ≤ p,q ≤ 1.0, -2 dB ≤ SNR ≤ 10 dB, and illustrated. Thus, this work has important implications towards efficient utilization of bandwidth, and also in greening of communication technologies which is highly needed. The latter is because the performance-improvement, achieved in case of STTS-CPSK receiver, can be translated into an equivalent advantage of EMF-reduction appropriately

Negative-weight percolation

We describe a percolation problem on lattices (graphs, networks), with edge weights drawn from disorder distributions that allow for weights (or distances) of either sign, i.e. including negative weights. We are interested whether there are spanning paths or loops of total negative weight. This kind of percolation problem is fundamentally different from conventional percolation problems, e.g. it does not exhibit transitivity, hence no simple definition of clusters, and several spanning paths/loops might coexist in the percolation regime at the same time. Furthermore, to study this percolation problem numerically, one has to perform a non-trivial transformation of the original graph and apply sophisticated matching algorithms. Using this approach, we study the corresponding percolation transitions on large square, hexagonal and cubic lattices for two types of disorder distributions and determine the critical exponents. The results show that negative-weight percolation is in a different universality class compared to conventional bond/site percolation. On the other hand, negative-weight percolation seems to be related to the ferromagnet/spin-glass transition of random-bond Ising systems, at least in two dimensions.Comment: v1: 4 pages, 4 figures; v2: 10 pages, 7 figures, added results, text and reference

Phase transitions in diluted negative-weight percolation models

We investigate the geometric properties of loops on two-dimensional lattice graphs, where edge weights are drawn from a distribution that allows for positive and negative weights. We are interested in the appearance of spanning loops of total negative weight. The resulting percolation problem is fundamentally different from conventional percolation, as we have seen in a previous study of this model for the undiluted case. Here, we investigate how the percolation transition is affected by additional dilution. We consider two types of dilution: either a certain fraction of edges exhibit zero weight, or a fraction of edges is even absent. We study these systems numerically using exact combinatorial optimization techniques based on suitable transformations of the graphs and applying matching algorithms. We perform a finite-size scaling analysis to obtain the phase diagram and determine the critical properties of the phase boundary. We find that the first type of dilution does not change the universality class compared to the undiluted case whereas the second type of dilution leads to a change of the universality class.Comment: 8 pages, 7 figure

Analysis of the loop length distribution for the negative weight percolation problem in dimensions d=2 through 6

We consider the negative weight percolation (NWP) problem on hypercubic lattice graphs with fully periodic boundary conditions in all relevant dimensions from d=2 to the upper critical dimension d=6. The problem exhibits edge weights drawn from disorder distributions that allow for weights of either sign. We are interested in in the full ensemble of loops with negative weight, i.e. non-trivial (system spanning) loops as well as topologically trivial ("small") loops. The NWP phenomenon refers to the disorder driven proliferation of system spanning loops of total negative weight. While previous studies where focused on the latter loops, we here put under scrutiny the ensemble of small loops. Our aim is to characterize -using this extensive and exhaustive numerical study- the loop length distribution of the small loops right at and below the critical point of the hypercubic setups by means of two independent critical exponents. These can further be related to the results of previous finite-size scaling analyses carried out for the system spanning loops. For the numerical simulations we employed a mapping of the NWP model to a combinatorial optimization problem that can be solved exactly by using sophisticated matching algorithms. This allowed us to study here numerically exact very large systems with high statistics.Comment: 7 pages, 4 figures, 2 tables, paper summary available at http://www.papercore.org/Kajantie2000. arXiv admin note: substantial text overlap with arXiv:1003.1591, arXiv:1005.5637, arXiv:1107.174

Prioritizing BIM Capabilities of an Organization: An Interpretive Structural Modeling Analysis

The Indian Architectural Engineering and Construction sector is grappling with the adoption of BIM as is evident from a relatively low level of adoption. While there have been sufficient number of successful (and unsuccessful) project level implementations of BIM in India, the maturity level of the overall industry and its constituents remains relatively low. One of the challenges faced, especially at the organizational level, is an understanding and development of the organization's BIM capabilities. These capabilities need attention in terms of their effectiveness and hierarchy of implementation in order to overcome the challenges of adoption and increasing maturity levels in BIM usage. The inability to identify crucial BIM capabilities is one of the primary barriers to ineffective BIM implementation and slow adoption in India. The aim of this study is to investigate the dynamics of different BIM capabilities and to understand how these capabilities can be represented as a set of interrelated elements by adopting Interpretive Structure Modeling (ISM) technique Accordingly, a clear understanding regarding the nature of each BIM capability is developed that will help the organizations to plan the strategic implementation of BIM on any project and gain systematic, logical and productive results. Through the three-phased study, it was concluded that BIM capabilities namely visualization, energy and environment analysis, structural analysis, MEP system modelling, constructability analysis, and BIM for as-built were found to be the independent BIM capabilities having strong driving power but weak dependence power. Facilities management is a dependent BIM capability with weak driving power but strong dependence power. This study provides a roadmap to BIM implementers by highlighting the driving and dependence power of each BIM capability which is deemed useful for enhanced delivery of construction projects. Significant theoretical and practical implications are envisioned for both researchers and project managers through the findings of this study