Performance of concrete wharves constructed between 1901 and 1928 at the Port of Montréal

An evaluation of concrete properties of five wharves in the Port of Montréal, constructed between 1901 and 1928, was undertaken to investigate the underlying causes of deterioration. The evaluated wharves consisted of either reinforced concrete caissons or massive concrete elements. The wharves were used in the past either as cargo loading docks or for the storage of various materials, some of which were detrimental to concrete.The evaluation program included visual examination of distressed concrete located above water level and the determination of compressive strength, modulus of elasticity, rapid chloride ion permeability (RCP), water soluble chloride ion penetration profiles, as well as a detailed microstructural examination. This article discusses the various results pertaining to the quality of the concrete and Gunite repairs found in old marine structures such as these, where various modes of degradation were present including ice abrasion, cracking and spalling, alkali-silica reaction (ASR), sulfate attack, and frost damage. These various modes of deterioration affected the quality of concrete in all examined wharves as well as that of previous repair work, demonstrating the need for new repairs. However, despite exhibiting signs of severe damage, the concrete wharves had reasonable strength and elastic modulus values enabling rehabilitation to increase service life.     

Parametric-based brain Magnetic Resonance Elastography using a Rayleigh damping material model

The three-parameter Rayleigh damping (RD) model applied to time-harmonic Magnetic Resonance Elastography (MRE) has potential to better characterise fluid-saturated tissue systems. However, it is not uniquely identifiable at a single frequency. One solution to this problem involves simultaneous inverse problem solution of multiple input frequencies over a broad range. As data is often limited, an alternative elegant solution is a parametric RD reconstruction, where one of the RD parameters (μ_I or ρ_I) is globally constrained allowing accurate identification of the remaining two RD parameters. This research examines this parametric inversion approach as applied to in vivo brain imaging.     

Modeling 3D seismic problems using high-performance computing systems

This paper examines some issues in numerical modeling of seismology in three-dimensional space on high-performance computing systems. As a method of modeling, the grid-characteristic method is used. This method allows accurate staging of different contact conditions and is suitable for the most physically correct solutions of problems of seismology and seismic prospecting in complex heterogeneous media. We use the grid-characteristic schemes up to the 4th order accuracy inclusive. The software package is parallelized for work in a distributed clustered medium using the MPI technology. We present the results of the simulation of the Love and Rayleigh surface seismic waves, as well as the passage of seismic waves initiated by an earthquake’s hypocenter to the earth’s surface through a multilayer geological formation.     

Thickness Gauging of Thin Metalware with Ultrasound Excited by Laser Nanopulses

It has been established that an ultrasonic pulse is split when Lamb ultrasonic waves are excited in thin metalware by a thermosonic emitter 3 mm or more in diameter. This makes it possible to measure the group velocity of ultrasonic waves. A technique is proposed for thickness gauging of articles based on the dependence of the velocity on the vibration frequency and article thickness (dispersion curves).     

The Prototype for a Monitoring System for a Photon Spectrometer Based on Lead-Tungstate Crystals

A monitoring system for the prototype of a Photon Spectrometer based on the lead-tungstate crystals of the ALICE experiment at the LHC collider. Light-emitting diodes are used as a source of light test signals simulating scintillations in crystals. The system provides individual control of the spectrometer's 64 channels. A relative channel monitoring stability of 1.2 × 10^–3 was achieved upon exposing the spectrometer to a beam for a period of 100h.     

Temperature-Dependent Microstructural Evolution of Al-Rich Medium-Mn Steel During Intercritical Annealing

Metallurgical and Materials Transactions A - Medium-Mn automotive sheet steels require optimized heat-treatment processes to obtain benefits caused by strain-induced martensitic transformation of...     

The RFR-4 X-ray Streak Camera

The RFR-4 X-ray streak camera with a slit scan designed on the basis of an X-ray sensitive evacuated image tube is described. The obtained images are recorded using a charge-coupled device (CCD) camera. The basic parameters of the X-ray streak camera are as follows: (1) the recorded spectral range starts at 0.1 keV; (2) the time resolution is as high as 30 ps; (3) the spatial resolution is five pairs of lines per millimeter (for a contrast ratio of 0.5); (4) the dynamic recording range is as high as 2000; and (5) the detectability is 2 × 10⁵ quanta/(cm²ns) (for a quantum energy of 1.5 keV). The design of the device and the purpose and operation of its components are described. The streak camera is equipped with a gate-valve unit with an autonomous evacuation system; this allows one to use it in installations where the working-chamber pressure increases dynamically up to 0.1 Torr. The sharp-focusing operating mode, which allows one to increase the device's sensitivity by an order of magnitude without loss in the time resolution, is described. The streak camera was used to record the X radiation in experiments with various targets performed at the ISKRA-4 and ISKRA-5 laser installations and the SIGNAL-2 Z-pinch installation.     

Self-administration of ethanol and saccharin in newborn rats: Effects on suckling plasticity.

Responsiveness to a surrogate nipple providing water, saccharin, 5% ethanol, or 10% ethanol was tested in newborn rats naive to suckling (3–5 hr old) on Postnatal Day (P) 0 and in older neonates with regular suckling experience on P1 or P2. At all ages, pups demonstrated greater nipple attachment for saccharin or 5% ethanol than for water. Intake of saccharin and 5% ethanol was high in newborns, far exceeding that of water. At P1 and P2, pups exhibited a preference for saccharin, but not for 5% ethanol. Preexposure to a nipple providing ethanol or saccharin (but not a nipple alone or fluids alone) increased subsequent responsiveness toward an empty surrogate nipple (no fluid), both 1 hr and 24 hr after preexposure. Although, during preexposure, pups responded most positively to the nipple providing saccharin, the longest time spent on an empty nipple was observed in pups preexposed to 10% ethanol. (PsycINFO Database Record (c) 2010 APA, all rights reserved)