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In the Yan'an gas field, southeast of Ordos Basin, the discovered natural gas reserves are 114 billion cubic meters. Highly productive gas reservoirs were formed in paleokarst. By using 164 samples from 27cores, the geochemical study of diagenetic evolution was carried out, and the relationship between different diagenesis environments was discussed by using scanning electron microscopy, carbon and oxygen isotope, and isotopic and fluid inclusion microthermometric observations. Results show that the lithology of reservoir is anhydrite-bearing mud powder crystal dolomite, powder crystal dolomite, and karst breccia dolomite; the filling includes dolomite, calcite, anhydrite, quartz, fluorite, and clay minerals; δ13C (‰ PDB) value is between −6.31‰ and 1.01‰, δ18O (‰ PDB) value ranges from −11.36‰ to −6.54‰, and the 87Sr/86Sr value ranges from 0.7077 to 0.7081. The overall carbon isotope of Majiagou Formation decreases first and then increases, and the strontium isotope evolution curve generally increases first and then decreases, indicating that the water environment of Majiagou Formation experienced a relatively high salinity concentration period and a relative desalinization period during deposition. The stratigraphic development shows a cyclical trend, responding to the multistage transgression and regression process. The homogenization temperature of fluid inclusions is 70–100°C, salinity is 0–3.5%, homogenization temperature of fluid inclusions is 70–100°C, salinity is >3.5%, homogenization temperature of fluid inclusions is 100–160°C, salinity is 0–3.5%, homogenization temperature of fluid inclusions is 100–160°C, salinity is >3.5%, homogenization temperature of fluid inclusion temperature is 160–200°C, and salinity is >3.5%, indicating that the fluid source in the sedimentation and diagenesis process is seawater, atmospheric freshwater, hydrocarbon fluid, and deep thermal fluid. The diagenetic environments are divided into marine diagenetic environments, metric freshwater diagenetic environments, and burial diagenetic environments. [ABSTRACT FROM AUTHOR]

The structure and morphology of Cu films deposited by DC magnetron sputtering on silicon and stainless-steel substrates at different deposition temperatures of −140 °C, −95 °C, −55 °C, 25 °C (RT), 50 °C, and 200 °C were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was found that all Cu films presented strong orientation of the (111) and (200) peaks. The Cu films deposited at low temperatures (lower than −55 °C) showed the bilayer structures, in which the upper layer appeared to be a loose and porous structure and the lower layer near the substrate had a fine and dense structure that consisted of small grains. In addition, the Cu films deposited at low temperatures could be observed a large roughness. The roughness tended to decline and then increase with the rising of deposition temperature. The ball-on-disc reciprocating sliding tribometer was employed to evaluate the tribological behaviors of the Cu films at current-carrying levels of 0 A, 0.5 A, and 1.0 A. The results revealed that the Cu films deposited at low temperatures exhibited outstanding current-carrying friction performance and low electrical contact resistance (ECR), peeling only at 0.5 A and 1.0 A. Nevertheless, the Cu films deposited at the relatively high temperature exhibited oxidative wear caused by electric arc ablation at 0.5 A and 1.0 A. Additionally, the wear mechanism was discussed in terms of the structure and morphology of the wear track and formation of the tribo-film. [ABSTRACT FROM AUTHOR]

In this study, the corrosion behavior of carbon steel in crude oil–water–CO2/H2S multiphase environments simulating the service conditions of a production well and ground gathering pipeline of a carbonate oilfield was explored by weight loss tests and surface analysis techniques. The results show that the presence of crude oil significantly reduces the corrosion rate of 80SS casing and L245 pipeline steels, but it favors the occurrence of localized corrosion at middle-high water cuts. The corrosion of 80SS steel with the variation in the water cut obeys a similar pattern under different environmental conditions. When the water cut is higher than 50%, the corrosion rate obviously enhanced, and the corrosion form changes from uniform corrosion to localized corrosion due to the inhomogeneous wetting of crude oil and water under the test conditions. Benefiting from the synergistic corrosion inhibition of crude oil and a protective sulfur-rich film, the steel demonstrates a relatively low corrosion rate at a high water cut of 80%, however, this is higher than that at middle-low water cuts. [ABSTRACT FROM AUTHOR]

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Vibration and acoustic noise limit the application of switched reluctance motors (SRMs). Because the radial vibration of the stator is the primary source of the acoustic noise of SRMs, the modal analysis of the stator vibration is an important and effective way to reduce the acoustic noise. In this paper, we construct eight computational models by varying the structural forms, height, quantity, and shape of radiating ribs to investigate the influence of radiating ribs on the mechanical resonant frequencies, under the condition of the same amount of radiating rib material. We apply three-dimensional finite-element modal analysis to accurately analyze these models. Finally, we derive an optimal structure of the radiating rib to lower the acoustic noise level of SRMs and dissipate heat. Index Terms--Acoustic noise, modal analysis, radiating rib, switched reluctance motor.

In a high-temperature superconducting (HTS) transformer leakage magnetic field, especially its radial component, decreases the critical current and increases the ac losses in the tapes. Because of zero resistance of HTS tapes a slight unbalance among the branch inductances of the windings may result in heavy circulating current, however, an accurate calculation of it must depend on the magnetic field analysis. Thus, a numerical analysis of the leakage magnetic field is especially necessary for an HTS transformer design. In this paper the leakage magnetic field of several transformer geometries is studied by finite element method, and based on it, the circulating current distribution is calculated. Some suggestions for improving the leakage field and circulating current distribution are presented to make HTS transformers more efficient. Index Terms--Circulating current, finite element method (FEM), HTS transformer, leakage magnetic field.

ZnO quantum dots sensitized SnO2 porous nanowires were fabricated and designed for UV excitation gas sensor. The ZnO/SnO2 composite (SZQ1%) with the molar proportion of 1:100 exhibits excellent sensing properties to NO2 gas under UV irradiation at 40 °C. The limits of detection of the SZQ1% sensor is 100 ppb. The humidity stability of SZQ1% was also measured and discussed by DC reversed circuit and complex impedance curves. The gas sensing mechanism is well discussed and illustrated to the ZnO quantum dots sensitized and the increased photo-generated carriers under UV irradiation. [ABSTRACT FROM AUTHOR]