The temperature dependence of the isothermal bulk modulus at 1 bar pressure

It is well established that the product of the volume coefficient of thermal expansion and the bulk modulus is nearly constant at temperatures higher than the Debye temperature. Using this approximation allows predicting the values of the bulk modulus. The derived analytical solution for the temperature dependence of the isothermal bulk modulus has been applied to ten substances. The good correlations to the experiments indicate that the expression may be useful for substances for which bulk modulus data are lacking

Probabilistic Grid-based Collision Risk Prediction for Driving Application

International audienceIn the recent years, more and more modern cars have been equipped with perception capabilities. One of the key applications of such perception systems is the estimation of a risk of collision. This is necessary for both Advanced Driver Assistance Systems and Autonomous Navigation. Most approach for risk estimation propose to detect and track the dynamic objects in the scene. Then the risk is estimated as a Time To Collision (TTC) by projecting the object's trajectory in the future. In this paper, we propose a new grid-based approach for collision risk prediction, based on the Hybrid-Sampling Bayesian Occupancy Filter framework. The idea is to compute an estimation of the TTC for each cell of the grid, instead of reasoning on objects. This strategy avoids to solve the difficult problem of multi-objects detection and tracking and provides a probabilistic estimation of the risk associated to each TTC value. After promising initial results, we propose in this paper to evaluate the relevance of the method for real on-road applications, by using a real-time implementation of our method in an experimental vehicle

Mission critical database for SPS accelerator measurements

In order to maintain efficient control over the hadron and lepton beams in CERN¹s SPS accelerator, measurements are of vital importance. Beam parameters such as intensities, positions and losses need to be rapidly available in the SPS control room to allow the operators to monitor, judge and act on beam physics conditions. For the 1994 SPS startup, a completely new and redesigned measurement system based on client and server C-programs running on UNIX-workstations was introduced. The kernel of this new measurement system is an on-line ORACLE database.The NIAM method was used for the database design as well as a technique to tag synchronized data with timeslots instead of timestamps. A great attention was paid to proper storage allocation for tables and indices since this has a major impact on the efficiency of the database, due to its time-critical nature. Many new features of Oracle7 were exploited to reduce the surrounding software.During the 1994 SPS physics run, this new measurement system was commissioned successfully and the infrastructure proved to be acceptably reliable. Hence, for the 1995 startup, the size of the measurement system was increased drastically to fulfill a variety of measurement needs. This proliferation of measurements beyond the initial scope showed the correct design of the system, as well as the performance limitations within the actual hardware configuration. This paper describes the overall design and discusses performance issues of this critical system

PULSED ELECTRON BEAM ANNEALING OF As AND B IMPLANTED SILICON

p-type (100) silicon wafers have been implanted either by As or B ions at 20 and 200 keV energies and doses of 1016cm-2. Pulsed electron beam annealing has been performed with fluences of 1.1 and 1.4 J/cm2 using a mean electron energy of 15 keV. The pulse duration was 50 ns. The annealed layers have been investigated by Rutherford backscattering under random and channeling conditions and by S.I.M.S. profiling. Good crystal regrowth and high dopant activation occur in all cases except for the 200 keV Boron implant. Impurities redistribution is observed but no significant segregation effects appear. The experimental profiles are in good agreement with a diffusion model using a modified green function solution and taking into account dopant diffusion in liquid phase and the computed melt front location. The deduced diffusion coefficient are in the 5.10-5cm2/s range for boron and 2.10-4cm2/s range for arsenic

Ultrasonic roll bite measurements in cold rolling: Contact length and strip thickness

In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip flatness defects and thickness inhomogeneity. To control the process, online process measurements are usually carried out; such as the rolling load, forward slip and strip tensions at each stand. Shape defects of the strip are usually evaluated after the last stand of a rolling mill thanks to a flatness measuring roll. However, none of these measurements is made within the roll bite itself due to the harsh conditions taking place in that area. This paper presents a sensor capable of monitoring strip thickness variations as well as roll bite length in situ and in real time. The sensor emits ultrasonic pulses that reflect from the interface between the roll and the strip. Both the time-of-flight of the pulses and the reflection coefficient (the ratio of the amplitude of the reflected signal to that of the incident signal) are recorded. The sensor system was incorporated into a work roll and tested on a pilot rolling mill. Measurements were taken as steel strips were rolled under several lubrication conditions. Strip thickness variation and roll-bite length obtained from the experimental data agree well with numerical results computed with a cold rolling model in the mixed lubrication regime

Comparison between SiN x :H and hydrogen passivation of electromagnetically casted multicrystalline silicon material

International audienceThis work intends to compare two different passivation methods for electromagnetically continuous pulling silicon (EMCP): remote plasma hydrogenation and remote plasma enhanced CVD of SiN followed by high-temperature sintering. All experiments are carried out on textured and non-textured EMCP samples from the same ingot. To check the effect of high-temperature diffusion on EMCP, a n +-emitter is formed on one group of the samples using POCl 3 diffusion. Passivation capabilities of both techniques are checked using measurements of minority carrier lifetime by means of microwave photoconductance decay mapping. Solar cells are made to compare lifetime measurement with cell parameters.

Inter-vehicle gap statistics on signal-controlled crossroads

We investigate a microscopical structure in a chain of cars waiting at a red signal on signal-controlled crossroads. Presented is an one-dimensional space-continuous thermodynamical model leading to an excellent agreement with the data measured.Moreover, we demonstrate that an inter-vehicle spacing distribution disclosed in relevant traffic data agrees with the thermal-balance distribution of particles in the thermodynamical traffic gas (discussed in [1]) with a high inverse temperature (corresponding to a strong traffic congestion). Therefore, as we affirm, such a system of stationary cars can be understood as a specific state of the traffic sample operating inside a congested traffic stream.Comment: 6 pages, 4 figures, accepted for publication in J. Phys. A: Math. Theo

High-temperature oxidation of nickel-based alloys and estimation of the adhesion strength of resulting oxide layers

The kinetics of isothermal oxidation (1100°C) of commercial nickel-based alloys with different content of sulfur (0.22–3.2 wt ppm) is studied. The adhesion strength in a metal/oxide system is estimated as a function of sulfur content and duration of high-temperature exposure. The scratch-test technique is proposed to quantitatively estimate the work of adhesion of resulting oxide films. It is found that the film microstructure is composed of an inner α-Al2O3 layer and an outer NiAl2O4 spinel layer, which are separated by discrete inclusions of TiO2. Residual stresses in the oxide film are experimentally determined by X-ray diffraction. spinel layer, which are separated by discrete inclusions of TiO2. Residual stresses in the oxide film are experimentally determined by X-ray diffractio

Computed tomography porosity and spherical indentation for determining cortical bone millimetre-scale mechanical properties

The cortex of the femoral neck is a key structural element of the human body, yet there is not a reliable metric for predicting the mechanical properties of the bone in this critical region. This study explored the use of a range of non-destructive metrics to measure femoral neck cortical bone stiffness at the millimetre length scale. A range of testing methods and imaging techniques were assessed for their ability to measure or predict the mechanical properties of cortical bone samples obtained from the femoral neck of hip replacement patients. Techniques that can potentially be applied in vivo to measure bone stiffness, including computed tomography (CT), bulk wave ultrasound (BWUS) and indentation, were compared against in vitro techniques, including compression testing, density measurements and resonant ultrasound spectroscopy. Porosity, as measured by micro-CT, correlated with femoral neck cortical bone’s elastic modulus and ultimate compressive strength at the millimetre length scale. Large-tip spherical indentation also correlated with bone mechanical properties at this length scale but to a lesser extent. As the elastic mechanical properties of cortical bone correlated with porosity, we would recommend further development of technologies that can safely measure cortical porosity in vivo. Introductio