Research on the 3D Reverse Time Migration Technique for Internal Defects Imaging and Sensor Settings of Pressure Pipelines.

Although pressure pipelines serve as a secure and energy-efficient means of transporting oil, gas, and chemicals, they are susceptible to fatigue cracks over extended periods of cyclic loading due to the challenging operational conditions. Their quality and efficiency directly affect the safe operation of the project. Therefore, a thorough and precise characterization approach towards pressure pipelines can proactively mitigate safety risks and yield substantial economic and societal benefits. At present, the current mainstream 2D ultrasound imaging technology faces challenges in fully visualizing the internal defects and topography of pressure pipelines. Reverse time migration (RTM), widely employed in geophysical exploration, has the capability to visualize intricate geological structures. In this paper, we introduced the RTM into the realm of ultrasonic non-destructive testing, and proposed a 3D ultrasonic RTM imaging method for internal defects and sensor settings of pressure pipelines. To accurately simulate the extrapolation of wave field in 3D pressure pipelines, we set the absorbing boundary and double free boundary in cylindrical coordinates. Subsequently, using the 3D ultrasonic RTM approach, we attained higher-precision 3D imaging of internal defects in the pressure pipelines through suppressing imaging artifacts. By comparing and analyzing the imaging results of different sensor settings, the design of the observation system is optimized to provide a basis for the imaging and interpretation of actual data. Both simulations and actual field data demonstrate that our approach delivers top-notch 3D imaging of pipeline defects (with an imaging range accuracy up to 97.85%). This method takes into consideration the complexities of multiple scattering and mode conversions occurring at the base of the defects as well as the optimal sensor settings.

Ultrafast Synthesis and Thermoelectric Properties of Mn1+ xTe Compounds.

MnTe compounds show great potential for thermoelectric applications in the intermediate temperature range (500-800 K) because of their large Seebeck coefficient and intrinsically low thermal conductivity. So far, the existing methods for the synthesis of MnTe compounds remain constrained to multistep processes that are time- and energy-intensive. Herein, we demonstrate ultrafast synthesis of high-density bulk MnTe compounds using a combination of self-propagating high-temperature synthesis (SHS) and plasma activated sintering. The entire synthesis and processing procedure takes less than 1 h. The thermodynamic consideration suggests that the SHS process includes two steps: (1) Mn + 2Te → MnTe2 + Q1 and (2) MnTe2 → MnTe + Te. With the heat released by step (1), the process moved in cycle and finished in a rather short time. The effect of extra Mn content on the structure and thermoelectric properties was investigated. There is some solubility limit of extra Mn in the Mn1+ xTe compound. The extra Mn occupy interstitial sites, leading to a decrease of carrier concentration while enhancing Seebeck coefficient and decreasing thermal conductivity. Low-temperature heat capacity data indicates that the Mn1.06Te compound has a high effective mass of 8.34 m0 and a low Debye temperature of 186 K, which are beneficial for the large Seebeck coefficient and low thermal conductivity. Therefore, the maximum ZT value reaches 0.57 at 850 K for the Mn1.06Te compound.

Relationship between Vitamin D receptor gene polymorphism and renal cell carcinoma susceptibility.

AIM OF STUDY: Results on the association of Vitamin D receptor (VDR) gene polymorphism with renal cell carcinoma (RCC) susceptibility from the present reports are still debating. This meta-analysis was conducted to assess the association of VDR ApaI (rs7975232), BsmI (rs1544410), TaqI (rs731236), and Fok1 (rs2228570) gene polymorphisms with RCC risk. MATERIALS AND METHODS: The association studies were recruited from PubMed on May 1, 2016, and eligible reports were extracted and data were synthesized using meta-analysis method. RESULT: Six investigations were included into this meta-analysis for the relationship between VDR gene polymorphism and RCC susceptibility. In this meta-analysis, the ApaI A allele, AA genotype, aa genotype, and Fok1 FF genotype were associated with RCC susceptibility in Asians. However, VDR BsmI and TaqI gene polymorphisms were not associated with the RCC risk in Asians, Caucasians, and overall populations. Furthermore, Fok1 gene polymorphism was not associated with the RCC risk in Caucasians and overall populations. CONCLUSION: ApaI gene polymorphism and Fok1 FF genotype were associated with RCC susceptibility in Asians.