Simulation of Nondestructive Inspection of Nuclear Resonance Fluorescence Based on Electron Accelerator

Nuclear resonance fluorescence (NRF) is an emerging nondestructive active inspection technology. Specific isotopes can be identified by analyzing the characteristic energy recorded in the gamma spectrum. This technology plays an important role in the scanning inspection of small containers containing unknown explosives. In this paper, an NRF backscatter inspection scheme is optimized using Monte Carlo simulation program based on the X-ray source generated by electron accelerator bremsstrahlung radiation. After optimized design, X-ray leakage rate is reduced by 386 times, the beam asymmetry is less than 2%, the beam uniformity is more than 70%. The NRF characteristic energy spectrum of graphite samples and ammonium nitrate sample obtained by HPGe detector verifies the feasibility of the design scheme. The innovative application of importance sampling technique improves the simulation calculation efficiency of graphite sample by 72.23 times. The design scheme and calculation results provide technical support for the research and development of NRF based non-destructive nuclear detection system

Numerical simulation for optimizing the nozzle of moist-mix shotcrete based on orthogonal test

The nozzles of moist-mix shotcrete are the key parts of forming a steady jet flow field and ensuring the uniform mixing of water and other ingredients. In this paper, for optimizing the nozzle of moist-mix shotcrete, both the internal and external field of a variety of spray nozzles were simulated and analyzed by adopting orthogonal test method with Fluent simulation software combined. Then the phase volume fraction and single-phase velocity of the outlet section of flow field inside the nozzles and cloud pictures including single-phase velocity and volume of different sections lengthways in the external flow field of nozzle were obtained. The results demonstrated that the change of different factors and different levels of the same factor affected the shotcreting performance of spray nozzle, but the effect degree is different. Additionally, compared with the traditional nozzle, the rationality of new-type nozzle structure was verified, which provided a basis for the improvement and optimization of the nozzle structure in the future

Anomaly data management and big data analytics: an application on disability datasets

Purpose - The disability datasets are the datasets that contain the information of disabled populations. By analyzing these datasets, professionals who work with disabled populations can have a better understanding of the inherent characteristics of the disabled populations, so that working plans and policies, which can effectively help the disabled populations, can be made accordingly. Design/methodology/approach - In this paper, the authors proposed a big data management and analytic approach for disability datasets. Findings - By using a set of data mining algorithms, the proposed approach can provide the following services. The data management scheme in the approach can improve the quality of disability data by estimating miss attribute values and detecting anomaly and low-quality data instances. The data mining scheme in the approach can explore useful patterns which reflect the correlation, association and interactional between the disability data attributes. Experiments based on real-world dataset are conducted at the end to prove the effectiveness of the approach. Originality/value - The proposed approach can enable data-driven decision-making for professionals who work with disabled populations

Microstructure Characterization and Mechanical Properties of TiSi 2 -SiC-Ti 3 SiC 2 Composites Prepared by Spark Plasma Sintering

Dense TiSi 2 -SiC and TiSi 2 -SiC-Ti 3 SiC 2 composites in which SiC particles in 200-300 nm disperse, were reactively synthesized through spark plasma sintering (SPS) technique using TiC, Si, and C powders in micrometer as starting reactants. The phase constituents and microstructures of the samples were analyzed by X-ray diffraction, field emission scanning electron microscopy and transmission emission microscopy. The hardness, fracture toughness and bending strength of TiSi 2 -SiC and TiSi 2 -SiC-Ti 3 SiC 2 composites were tested at room temperature. The fracture toughness and bending strength of TiSi 2 -SiC-Ti 3 SiC 2 composites reach 5:4 AE 0:3 MPaÁm 1=2 and 700 AE 50 MPa, respectively. The factors leading to the improvement of the mechanical properties were discussed

Association between cognitive function and body composition in older adults: data from NHANES (1999–2002)

AimTo investigate the association between cognitive function and body composition in older adults.MethodsWe collected data on 2080 older adults (>60 years of age) from the National Health and Nutrition Examination Survey (NHANES) for the years 1999–2000 and 2001–2002. Candidate variables included: demographic data (sex, age, race, education level, marital status, poverty-to-income ratio), alcohol consumption, cardiovascular disease, diabetes, osteoporosis, total bone mineral density, and total fat mass. A logistic regression model was established to analyze the association between cognitive function and body composition in older adults. In addition, stratified logics regression analysis was performed by sex and age.ResultsBone mineral density significantly affects cognitive function in older adults (p<0.01). When examining the data according to sex, this correlation is present for women (p < 0.01). For men, though, it is not significant (p = 0.081). Stratified by age, total bone mineral density was significantly correlated with cognitive function in 60–70 and 70–80 years old people, but not in older adults older than 80 years(for 60–70 years old, p = 0.019; for 70–80 years old, p = 0.022). There was no significant correlation between total bone mineral density and cognitive function (p = 0.575).ConclusionThe decrease of total bone mineral density was significantly correlated with cognitive decline in the older adults, especially among women and older people in the 60 to 80 age group. There was no connection between total fat mass, total percent fat, total lean mass, appendicular lean mass, appendicular lean mass /BMI and cognitive function in the older adults

Empirical prediction of blast-induced vibration on adjacent tunnels

The blast-induced vibration during excavation by the drilling and blasting method has an important impact on the surrounding buildings/structures and auxiliary equipment. In particular, with the development of tunnel engineering, the impact of blasting vibration on tunnel construction has attracted extensive attention. Based on literature data statistics, this paper first explored the performance of several commonly used empirical equations in predicting the propagation and attenuation characteristics of blasting vibration on adjacent tunnels. Secondly, the relationships between the empirical parameters of the blasting vibration prediction equation and the geological strength index (GSI) of tunnel surrounding rock were discussed, and two new blasting vibration prediction equations based on site rock GSI were established to approximately predict blast-induced vibration on adjacent tunnels. Finally, the application feasibility of the established prediction equation in practical engineering was discussed based on field test data. The research results show that under the condition of multiple groups of data, the prediction performance of various prediction models does not differ significantly. With the increase of the GSI of the surrounding rock mass of the adjacent tunnel, the site coefficients β and k of the blasting vibration prediction equation in predicting PPV (peak particle velocity, resultant velocity) both show a decreasing trend as a whole. The site coefficient k is generally within 3,000. Two new empirical prediction equations of blasting vibration propagation and attenuation on adjacent tunnels under different site conditions were established: Eq. (14) for PPV and Eq. (15) for PPVi (max) (maximum value of the three component velocities; i = x, y, z represent peak component particle velocity). The verification analysis of five sites shows that these two equations have a certain practical application value. Compared with other empirical equations, these two equations do not need regression fitting blasting vibration data, they only used the GSI of the site rock mass, and they are more easy to use in the field when there is a lack of monitoring data

Promotion of Para-Chlorophenol Reduction and Extracellular Electron Transfer in an Anaerobic System at the Presence of Iron-Oxides

Anaerobic dechlorination of chlorophenols often subjects to their toxicity and recalcitrance, presenting low loading rate and poor degradation efficiency. In this study, in order to accelerate p-chlorophenol (p-CP) reduction and extracellular electron transfer in an anaerobic system, three iron-oxide nanoparticles, namely hematite, magnetite and ferrihydrite, were coupled into an anaerobic system, with the performance and underlying role of iron-oxide nanoparticles elucidated. The reductive dechlorination of p-CP was notably improved in the anaerobic systems coupled by hematite and magnetite, although ferrihydrite did not plays a positive role. Enhanced dechlorination of p-CP in hematite or magnetite coupled anaerobic system was linked to the obvious accumulation of acetate, lower oxidation–reduction potential and pH, which were beneficial for reductive dechlorination. Electron transfer could be enhanced by Fe2+/Fe3+ redox couple on the iron oxides surface formed through dissimilatory iron-reduction. This study demonstrated that the coupling of iron-oxide nanoparticles such as hematite and magnetite could be a promising alternative to the conventional anaerobic reduction process for the removal of CPs from wastewater

Benefit of Contact Force-Guided Catheter Ablation for Treating Premature Ventricular Contractions

We evaluated whether an irrigated contact force–sensing catheter would improve the safety and effectiveness of radiofrequency ablation of premature ventricular contractions originating from the right ventricular outflow tract. We retrospectively reviewed the charts of patients with symptomatic premature ventricular contractions who underwent ablation with a contact force–sensing catheter (56 patients, SmartTouch) or conventional catheter (59 patients, ThermoCool) at our hospital from August 2013 through December 2015. During a mean follow-up of 16 ± 5 months, 3 patients in the conventional group had recurrences, compared with none in the contact force group. Complications occurred only in the conventional group (one steam pop; 2 ablations suspended because of significantly increasing impedance). In the contact force group, the median contact force during ablation was 10 g (interquartile range, 7–14 g). Times for overall procedure (36.9 ± 5 min), fluoroscopy (86.3 ± 22.7 s), and ablation (60.3 ± 21.4 s) were significantly shorter in the contact force group than in the conventional group (46.2 ± 6.2 min, 107.7 ± 30 s, and 88.7 ± 32.3 s, respectively; P \u3c0.001). In the contact force group, cases with a force-time integral \u3c560 gram-seconds (g-s) had significantly longer procedure and fluoroscopy times (both P \u3c0.001) than did those with a force-time integral ≥560 g-s. These findings suggest that ablation of premature ventricular contractions originating from the right ventricular outflow tract with an irrigated contact force–sensing catheter instead of a conventional catheter shortens overall procedure, fluoroscopy, and ablation times without increasing risk of recurrence or complications