1,379 research outputs found

    Model for the free-volume distributions of equilibrium fluids

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    We introduce and test via molecular simulation a simple model for predicting the manner in which interparticle interactions and thermodynamic conditions impact the single-particle free-volume distributions of equilibrium fluids. The model suggests a scaling relationship for the density-dependent behavior of the hard-sphere system. It also predicts how the second virial coefficients of fluids with short-range attractions affect their free-volume distributions.Comment: 7 pages, 5 figure

    Structural anomalies of fluids: Origins in second and higher coordination shells

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    Compressing or cooling a fluid typically enhances its static interparticle correlations. However, there are notable exceptions. Isothermal compression can reduce the translational order of fluids that exhibit anomalous waterlike trends in their thermodynamic and transport properties, while isochoric cooling (or strengthening of attractive interactions) can have a similar effect on fluids of particles with short-range attractions. Recent simulation studies by Yan [Phys. Rev. E 76, 051201 (2007)] on the former type of system and Krekelberg [J. Chem. Phys. 127, 044502 (2007)] on the latter provide examples where such structural anomalies can be related to specific changes in second and more distant coordination shells of the radial distribution function. Here, we confirm the generality of this microscopic picture through analysis, via molecular simulation and integral equation theory, of coordination shell contributions to the two-body excess entropy for several related model fluids which incorporate different levels of molecular resolution. The results suggest that integral equation theory can be an effective and computationally inexpensive tool for assessing, based on the pair potential alone, whether new model systems are good candidates for exhibiting structural (and hence thermodynamic and transport) anomalies.Chemical Engineerin

    Analytical Expressions for Tunneling Time through Single and Double Barrier Structures

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    In the past, the quantum mechanical tunneling time through simple rectangular barrier has been obtained by various theoretical approaches including the dwell time, the phase delay time, the Larmor clock time and also using the numerical analysis of wave packets. The agreement among these approaches over a range of incident electron energy is far from satisfactory. In this manuscript, analytical expressions for the tunneling time are derived based on the group velocity approach (referred hereafter as the average particle time, Ï„APT) for single and double rectangular potential barriers under zero bias. The results of the single barrier case, including the limiting value of the tunneling time for various energy limits, are compared with these previous tunneling time calculations. The Ï„APT results provide physically meaningful tunneling times for zero and infinite incident energy limits of the electron. The Ï„APT for the double barrier structure is computed from the analytical solution as a function of the incident energy of the electron for two experimentally studied resonant tunneling structures. For both the single and double barrier cases, the effect of the structure parameters such as barrier width, height, and well width on the Ï„APT are obtained and reported

    New Model Of Enhanced Plasticity For Reinforced Concrete Structural Elements That Take Into Account The Effects Of Lateral Loading And Gravity

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    Reinforced concrete structures are exposed to a progression of activities all through their life expectancy which may be the purpose behind damage. Subsequently, rehabilitation of existing structures is typically performed either to restore structural limit because of decay or damage or to broaden existing structural limit due to expanded loads. To fortify existing structures, numerous new creative materials like progressed fiber-reinforced polymers (FRPs) are discovered to be acceptable substitute for reinforcing materials like steel. They are actualized to fortify the presentation of structural components in flexure, pivotal, shear, and twist. In a RC outline, migrating plastic pivots in the beam off from the column face is normally prescribed to broaden pliability of the edge. This could be accomplished through rib reinforced FRP retrofit of the joint. Furthermore, to it, thus we execute an expanded pliancy for the concrete structural components like column, beam, chunk, dividers then on. The primary motivation behind a wide range of structural frameworks utilized in the structure type of structures is to transfer gravity and horizontal loads effectively

    Community Work: theories, experiences and challenges

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    'Community Work: Theories, Experiences and Challenge' provides an insightful knowledge to human service professionals to work with communities. This compendium includes reflective writings on practices of diverse ways of working with communities to mitigate challenges posed by ecological, political, economic, social and cultural environment in the 21st century. This collaborative effort of academics and practitioners from Asia Pacific region is to promote and expand community work in the wider society

    Detecting Network Soft-failures with the Network Link Outlier Factor (NLOF)

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    In this paper, we describe and experimentally evaluate the performance of our Network Link Outlier Factor (NLOF) for detecting soft-failures in communication networks. The NLOF is computed using the throughput values derived from NetFlow records. The flow throughput values are clustered in two stages, outlier values are determined within each cluster, and the flow outliers are used to compute the outlier factor or score for each network link. When sampling NetFlow records across the full span of a network, NLOF enables the detection of soft-failures across the span of the network; large NLOF scores correlate well with links experiencing failure

    Historical and Projected Surface Temperature over India during the 20th and 21st century.

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    Surface Temperature (ST) over India has increased by ~0.055 K/decade during 1860-2005 and follows the global warming trend. Here, the natural and external forcings (e.g., natural and anthropogenic) responsible for ST variability are studied from Coupled Model Inter-comparison phase 5 (CMIP5) models during the 20th century and projections during the 21st century along with seasonal variability. Greenhouse Gases (GHG) and Land Use (LU) are the major factors that gave rise to warming during the 20th century. Anthropogenic Aerosols (AA) have slowed down the warming rate. The CMIP5 projection over India shows a sharp increase in ST under Representative Concentration Pathways (RCP) 8.5 where it reaches a maximum of 5 K by the end of the 21st century. Under RCP2.6 emission scenarios, ST increases up to the year 2050 and decreases afterwards. The seasonal variability of ST during the 21st century shows significant increase during summer. Analysis of rare heat and cold events for 2080-2099 relative to a base period of 1986-2006 under RCP8.5 scenarios reveals that both are likely to increase substantially. However, by controlling the regional AA and LU change in India, a reduction in further warming over India region might be achieved

    Pterygoid implant: Option for rehabilitation of the atrophic posterior maxilla

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    Background: The anatomy of the atrophic posterior maxilla presents many limitations to implant placement. Factors affecting implant placements include poor bone quality and quantity, location of maxillary sinus. Posterior cantilevers on implant prostheses produce complications, such as prosthesis fracture, screw loosening, loss of osseointegration, and crestal bone loss. Pterygoid implants are an alternative to grafting solutions for posterior maxillary rehabilitation. Aim: This systematic review describes various implant treatment options for posterior maxillary rehabilitation. It highlights the use of pterygoid implants as a graftless solution with its anatomy, technique of placement, and advantages. Conclusion: Pterygoid implants have high success rates, less bone loss, and good acceptance by patients thus being an excellent alternative to treat patients with severely atrophic maxilla. Clinical Significance: Pterygoid implants avoid the need for sinus lifts and grafting procedures. They allow anchorage in the posterior atrophied/resorbed maxilla, achieving proper stability, and high rates of long-term succ
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