Algebraic aspects of separation logic

We present an algebraic approach to separation logic. In particular, we give algebraic characterisations for all constructs of separation logic like assertions and commands. The algebraic view does not only yield new insights on separation logic but also shortens proofs and enables the use of automated theorem provers for verifying properties at a more abstract level

A Perturbed Projection Algorithm with Inertial Technique for Split Feasibility Problem

This paper deals with the split feasibility problem that requires to find a point closest to a closed convex set in one space such that its image under a linear transformation will be closest to another closed convex set in the image space. By combining perturbed strategy with inertial technique, we construct an inertial perturbed projection algorithm for solving the split feasibility problem. Under some suitable conditions, we show the asymptotic convergence. The results improve and extend the algorithms presented in Byrne (2002) and in Zhao and Yang (2005) and the related convergence theorem

Kinetic study of the oxide-assisted catalyst-free synthesis of silicon nitride nanowires

The synthesis of Si3N4 nanowires from the reaction of silicon nanoparticles with N2 in the 1200-1440 C temperature range is reported. The nitridation conditions are such that the reaction with nitrogen is favoured by the presence of silicon oxide in the particles and by the active oxidation of silicon without a catalyst. It is shown that the Si to Si3N4 conversion rate depends on the amount of silicon particles used in the experiments and that, in general, the reaction slows down for greater amounts. This trend is explained by particle stacking, which restricts the exchange of gases between the furnace atmosphere and the atmosphere around the inner particles. In a first stage, local oxygen partial pressure increases around the inner particles and inhibits nitridation locally. If the amount of reactant Si nanoparticles is small enough, this extrinsic effect is avoided and the intrinsic nitridation kinetics can be measured. Experiments show that intrinsic kinetics does not depend on temperature

CFD Simulation of Temperature Field Distribution of the Liquefied Hydrocarbon Spherical Tank Leaking

AbstractLiquefied hydrocarbon is normally stored under high pressure in overheating state in the spherical tank. Once leakage occurs, the liquefied hydrocarbon will quickly gasify and absorb a great deal of heat, making temperature of spherical tank decrease sharply. In order to investigate this process, physical model was established, and the Reynolds time averaged Navier-Stokes equation and k-ɛ turbulent model as the CFD simulation method were used in this study. The temperature distribution of the spherical tank and the environment after spherical tank pipeline leaking was analyzed. The influences of leakage location and leak area on the spherical tank temperature distribution were analyzed, and a meaningful conclusion was obtained. This study could provide theoretical basis and technical support for the safety control of liquefied hydrocarbon spherical tank leakage. © 2012 Published by Elsevier Ltd. Selection and/or peer-review (pre-review) under responsibility of the Capital University of Economics and Business, China Academy of Safety Science and Technology

The safety and reactogenicity of a reduced-antigen-content diphtheria-tetanus-acellular pertussis (dTpa) booster vaccine in healthy Vietnamese children

AbstractDespite effective infant immunization against pertussis, the disease continues to circulate due to waning immunity. Booster vaccinations against pertussis beyond infancy are widely recommended. In Vietnam, however, no recommendations for pertussis boosters beyond the second year of life exist. This open-label, single-centre study was designed to assess the safety of a single booster dose of reduced-antigen-content-diphtheria-tetanus-acellular-pertussis vaccine (dTpa) in 300 healthy Vietnamese children (mean age 7.9years), who had completed primary vaccination against diphtheria, tetanus and pertussis. Solicited symptoms were recorded for 4days and unsolicited and serious adverse events (SAEs) for 31days post-vaccination. Pain and fatigue were the most common solicited local and general symptoms in 35.0% and 14.0% of children, respectively. Grade 3 swelling occurred in 3 children; no large injection site reactions or SAEs were reported. The dTpa booster vaccine was well tolerated and this study supports its administration in school age Vietnamese children

A novel classification method combining adaptive local iterative filtering with singular value decomposition for fault diagnosis

As a novel time-frequency analysis method, adaptive local iterative filtering (ALIF) can decompose the time series into several stable components which contain the main fault information. In addition, the amplitude of singular value obtained by singular value decomposition (SVD) can reflect the energy distribution. Naturally, there are certain differences in the energy produced by different faults such as the broken tooth, wearing and normal. Thus, a novel method of mechanical fault classification method based on adaptive local iterative filtering and singular value decomposition is proposed in this paper. Firstly, ALIF method decomposed the original vibration signal into a number of stable components to establish an initial feature vector matrix. Then, the singular values energy corresponding to the feature matrix is employed as a criterion to identify various faults. Compared with the conventional EMD method by simulation experiments, ALIF method has obvious superiority in solving modal aliasing, which is more conducive to the advanced analysis. In this paper, the proposed method is employed to extract the fault information of rolling bearing fault signals from Case Western Reserve University Bearing Data Center. To further verify the effectiveness of the method, the case study is conducted at Drivetrain Diagnostics Simulator. To further illustrate the effectiveness of the method, the results obtained by this method are compared with EMD and EEMD. The results indicated the proposed method performs better in the classification of different mechanical faulty modes

Intrusions into Privacy in Video Chat Environments: Attacks and Countermeasures

Video chat systems such as Chatroulette have become increasingly popular as a way to meet and converse one-on-one via video and audio with other users online in an open and interactive manner. At the same time, security and privacy concerns inherent in such communication have been little explored. This paper presents one of the first investigations of the privacy threats found in such video chat systems, identifying three such threats, namely de-anonymization attacks, phishing attacks, and man-in-the-middle attacks. The paper further describes countermeasures against each of these attacks.Comment: 8 pages, submitted to WPE

Cryo-EM Studies of TMEM16F Calcium-Activated Ion Channel Suggest Features Important for Lipid Scrambling.

As a Ca2+-activated lipid scramblase and ion channel that mediates Ca2+ influx, TMEM16F relies on both functions to facilitate extracellular vesicle generation, blood coagulation, and bone formation. How a bona fide ion channel scrambles lipids remains elusive. Our structural analyses revealed the coexistence of an intact channel pore and PIP2-dependent protein conformation changes leading to membrane distortion. Correlated to the extent of membrane distortion, many tightly bound lipids are slanted. Structure-based mutagenesis studies further reveal that neutralization of some lipid-binding residues or those near membrane distortion specifically alters the onset of lipid scrambling, but not Ca2+ influx, thus identifying features outside of channel pore that are important for lipid scrambling. Together, our studies demonstrate that membrane distortion does not require open hydrophilic grooves facing the membrane interior and provide further evidence to suggest separate pathways for lipid scrambling and ion permeation