Amplitude, Latency, and Peak Velocity in Accommodation and Disaccommodation Dynamics

The aim of this work was to ascertain whether there are differences in amplitude, latency, and peak velocity of accommodation and disaccommodation responses when different analysis strategies are used to compute them, such as fitting different functions to the responses or for smoothing them prior to computing the parameters. Accommodation and disaccommodation responses from four subjects to pulse changes in demand were recorded by means of aberrometry. Three different strategies were followed to analyze such responses: fitting an exponential function to the experimental data; fitting a Boltzmann sigmoid function to the data; and smoothing the data. Amplitude, latency, and peak velocity of the responses were extracted. Significant differences were found between the peak velocity in accommodation computed by fitting an exponential function and smoothing the experimental data (mean difference 2.36 D/s). Regarding disaccommodation, significant differences were found between latency and peak velocity, calculated with the two same strategies (mean difference of 0.15 s and −3.56 D/s, resp.). The strategy used to analyze accommodation and disaccommodation responses seems to affect the parameters that describe accommodation and disaccommodation dynamics. These results highlight the importance of choosing the most adequate analysis strategy in each individual to obtain the parameters that characterize accommodation and disaccommodation dynamics.

U233 Data Evaluation for Criticality Study

The aim of this study is to investigate the available U233 cross section data for adequate calculation of critical benchmark experiments, to calculate the multiplication factor Keff for several benchmarks in both fast and thermal energy ranges. The evaluation of the U233 has been investigated using SAMMY code, in order to generate a useful database for criticality calculations; the computer code FITWR for experimental data fitting shows the same results obtained from the Bayes method included within the SAMMY code, with a slight difference in the results in the evaluated cross sections due to different mathematical methods having different results. Excellent results for the calculated Keff values are obtained for several benchmarks in the thermal and fast benchmarks considered in this study.

Mass Loss and Nose Shape Change on Ogive-nose Steel Projectiles During Concrete Penetration

The mass loss of the nose of projectile is an obvious phenomenon in high-speed penetration into concrete target. The mass loss percentage depends linearly on the impact velocities of projectile according to experimental data fitting results. A semi-empirical model, which can calculate the ogive-nose shape change due to mass loss, is developed in this paper. The modified penetration model shows that the penetration depth is influenced by nose erosion.

Research on Strength Calculation Model of 7A05 Aluminum Alloy Welding Heat-Affected Zone

In order to research the mechanic performance of 7A05 aluminum alloy, a series of tests, including tensile test about aluminum alloy substrate, tensile test about aluminum alloy butt welded joint, tensile test about transverse partition of aluminum alloy welded joint and hardness test were conducted. The results of these tests indicate that the strength and hardness of HAZ of this material exhibit a W-shaped reduction. There are an symmetrical softened area at 10~20mm from the center of weld. Due to ageing effect, the strength and hardness of HAZ can resume to 80%of the substrate one month after welding. Based on the analytical deduction and experimental data fitting, the theoretical strength model for HAZ of aluminum alloy is proposed. For the purpose of engineering design, the HAZ is transformed into a uniform strength reduction zone, the width and strength value is determined according to the principle of equal strength.

Experimental Analysis of Decohesive Phenomenon in Expanded Polystyrene under Bending and Tensile Loading Conditions

In this paper, the decohesive phenomenon of expanded polystyrene (EPS) is analysed using bending and tensile tests. Globally, the typical stress-strain curve is characterised by a wide linear or nonlinear elastic part, the plastic phase being almost neglected. The mechanical properties, such as the elastic modulus E* and the stress threshold σth*, increase with the EPS apparent density ρ*. The empirical equations have been proposed from experimental data fitting curve. The failure strain called εf, corresponding to the point where the final breakage occurs, decreases when the density value increases. Globally, these observations indicate a brittle behaviour of the EPS material under bending and tensile loading. On the other the hand, scanning electron microscopy (SEM) has been used in order to analyse the EPS fracture surfaces. The trans-beads (TB) fracture mode, where the crack grows through the beads, has sometimes been observed for the high diameters beads. But, according to all observations, the inter-beads (IB) mode generally seems to be the major mode of fracture. Therefore, this indicates that the EPS mechanical strength under bending and tensile loading essentially depends on the beads fusion quality.