A new measurement of the 122Sb half-life

Following significant discrepancies observed when decay-correcting 122Sb γ-peak count rates to a reference time, we looked at the literature supporting the presently recommended 2.7238(2) d (1σ) 122Sb half-life value as the source of these discrepancies. Investigation revealed that the value was derived from an inconsistent dataset and was published without reporting details of the experiment nor the uncertainty budget. In this work we performed a new measurement of the 122Sb half-life by measuring the 122Sb decay of neutron-activated antimony samples using state-of-the-art γ-detection systems characterized in terms of efficiency drift and random pulse pile-up. The measurement was carried out in two different laboratories with the same method. The resulting 2.69454(39) d and 2.69388(30) d (1σ) 122Sb half-life values are in agreement at the evaluated 10–4 relative combined standard uncertainty level but are significantly lower (1.07% and 1.10% lower, respectively) than the preexisting recommended value.

ACOUSTIC EMISSION AND DAMAGE CHARACTERISTICS OF ANTHRACITE UNDER DIFFERENT CONDITIONS

Acoustic emission (AE) can be used to observe the process of coal fracture propagation. Based on a press and acoustic-emission platform, the damage and acoustic-emission characteristics of anthracite with different loading rates, water amounts and sizes were studied. The results show that there is less acoustic emission in the initial compression stage of coal; acoustic emission is more active in the transition from elastic deformation to plastic deformation, which is manifested in the following aspects: the faster the loading rate, the higher is the number of acoustic-emission events; the peak count of acoustic emissions of a saturated-coal sample is significantly lower than that of a natural-coal sample. Coal samples and large coal samples emit even more sounds. Based on the normalization of acoustic-emission counts, the relationship between damage variables and stress-strain is studied, and it is characterized by an initial slow increase, followed by a rapid increase; however, different factors have a great influence on the damage-characteristic curve. The research results have a certain guiding significance for the coal and rock disaster prediction.

Monitoring damage in composite plates from crack initiation to macro-crack propagation combining linear and nonlinear ultrasonic techniques

In this article, a holistic technique for sensing damage initiation, as well as damage progression in composite plates, is presented combining linear and nonlinear ultrasonic techniques. For this investigation, multiple sets of composite plate specimens made of two different composite materials were fabricated to check if the proposed technique works for different types of specimens. The specimens were damaged by impact loading and then inspected by propagating Lamb waves through them. Different failure mechanisms, such as fiber breaks, matrix cracking, debonding, and delamination, cause composite damage. Two groups of composite specimens that were fabricated and damaged were glass fiber–reinforced polymer composite and basalt fiber–reinforced polymer composite. A chirp signal excited by PZT (lead zirconate titanate) transducer was propagated through undamaged and damaged specimens to investigate the effects of varying degrees of damage on the recorded signals. Both linear and nonlinear ultrasonic parameters were extracted from the recorded signals and analyzed. The change in the linear ultrasonic parameters such as the wave speed and attenuation with damage progression were recorded. A new nonlinear ultrasonic parameter, the sideband peak count or sideband peak count-index, is also introduced and calculated from the recorded signals. It is observed that the nonlinear ultrasonic parameter can monitor the early stage of damage progression better than the linear ultrasonic parameters, while some linear ultrasonic parameters are more effective than the nonlinear ultrasonic parameter for monitoring the advanced stage of damage. Therefore, a combination of linear ultrasonic and nonlinear ultrasonic analyses is ideal for the holistic monitoring of the composite panels from the crack nucleation stage to the structural failure stage.

Optimization of Electro-Discharge Texturing Parameters for Steel Sheets’ Finishing Rollers

Exterior car-body parts are made of steel or aluminum sheets. Their formability and appearance after painting depends not only on the mechanical properties but also on their surface texture. The surface roughness characteristics, the roughness average Ra and the peak count Pc per centimeter depend on the texture of rolling mill’s finishing rollers, their wear and the degree of removal by the rolling mill. The research was carried out on heat-treated finishing rollers on the surface of which a controlled texture was created by changing the electro-discharge texturing (EDT) parameters. Parameters and the number of electro-discharge texturing experiments were optimized using full four-factor experiment techniques at the upper and lower levels of the parameters in the form of 24. The significance of the impact of individual EDT parameters and their interactions was identified based on the variance results. The ANOVA variance analysis results confirmed that the roughness Ra and the peak count Pc depend primarily on peak current (Ip), discharge peak voltage (Up), pulse on time (Pont) and pulse off time (Pofft). Optimization of the effect of the above parameters on the target roughness RaT,FR values and the peak count PcT,FR of finishing rollers was performed by the response surface methodology (RSM). Obtained regression models describe relationships between the input parameters of the electro-discharge texturing of finishing rollers and the output characteristics of the RaT,FR and the PcT,FR texture to a very high degree. The reliability of the electro-discharge texturing process of working rollers was assessed using the process capability index Cpk.

A union neutron-gamma logging method for determination of uranium-radium disequilibrium coefficient

Owing to the influence of continuous running of ground water, the uranium atoms can be separated physically from their daughters for the reason of different solubilities and the uranium deposit often shows the disequilibrium feature between uranium and its daughter products (radium principally). It is important, when spectral gamma ray logging, to quantify the uranium content which can cause inaccuracy of the result. This paper, based on spectral ? ray logging method, proposes a neutron-gamma logging method to determine the coefficient of uranium-radium disequilibrium. In this method, characteristic peak count rate of uranium is taken from prompt fission neutron logging, whereas characteristic peak count rate of radium, thorium and potassium are taken from spectral gamma ray logging. Based on this method, the union logging tool including epithermal neutron, thermal neutron, and gamma detector along with D-T generator, have been developed. The experimental results, in standard model wells, show that this method is in good agreement within 7% in core assay results. It shows that the union neutron-? logging method can be used for field uranium logging jobs.