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Objective. To explore the features and diagnostic value of computed tomography (CT) imaging in cases of thymic cysts. Methods. A total of 24 cases of the thymic cysts (confirmed by postoperative pathology) were retrospectively analyzed. The location, morphology, and density of the thymic cysts were summarized, and the changes in CT value of the region of interest (ROI) in the thymic cysts between noncontrast enhanced and enhanced chest scans were compared and classified. Results. The average long-axis dimension was 17.50 ± 6.00 mm, the CT value range across the 24 cases was 5–81 HU, and the average CT value of the noncontrast enhanced scans was 39.75 ± 20.66 HU. The CT value in the noncontrast enhanced scan was >20 HU in 79% of the sample cases. The CT value in the ROI of the thymic cysts under enhanced scan showed a significant decrease in 15 cases, a significant increase in 5 cases, and an insignificant change in 4 cases. Conclusion. The CT values of the thymic cysts in the enhanced scans were generally lower than in the noncontrast enhanced scans, which might be a valuable finding for thymic cysts diagnosis.

The brittleness prediction of shale formations is of interest to researchers nowadays. Conventional methods of brittleness prediction are usually based on isotropic models while shale is anisotropic. In order to obtain a better prediction of shale brittleness, our study firstly proposed a novel brittleness index equation based on the Voigt–Reuss–Hill average, which combines two classical isotropic methods. The proposed method introduces upper and lower brittleness bounds, which take the uncertainty of brittleness prediction into consideration. In addition, this method can give us acceptable predictions by using limited input values. Secondly, an anisotropic rock physics model was constructed. Two parameters were introduced into our model, which can be used to simulate the lamination of clay minerals and the dip angle of formation. In addition, rock physics templates have been built to analyze the sensitivity of brittleness parameters. Finally, the effects of kerogen, pore structure, clay lamination and shale formation dip have been investigated in terms of anisotropy. The prediction shows that the vertical/horizontal Young’s modulus is always below one while the vertical/horizontal Poisson’s ratio (PR) can be either greater or less than 1. Our study finds different degrees of shale lamination may be the explanation for the random distribution of V ani (the ratio of vertical PR to horizontal PR).

The construction of a shale rock physics model and the selection of an appropriate brittleness index ( BI ) are two significant steps that can influence the accuracy of brittleness prediction. On one hand, the existing models of kerogen-rich shale are controversial, so a reasonable rock physics model needs to be built. On the other hand, several types of equations already exist for predicting the BI whose feasibility needs to be carefully considered. This study constructed a kerogen-rich rock physics model by performing the selfconsistent approximation and the differential effective medium theory to model intercoupled clay and kerogen mixtures. The feasibility of our model was confirmed by comparison with classical models, showing better accuracy. Templates were constructed based on our model to link physical properties and the BI . Different equations for the BI had different sensitivities, making them suitable for different types of formations. Equations based on Young’s Modulus were sensitive to variations in lithology, while those using Lame’s Coefficients were sensitive to porosity and pore fluids. Physical information must be considered to improve brittleness prediction.

Geothermal reservoir are the vehicle of geothermal resources and their occurrence as well as the storage mass. Precise description and evaluation of geothermal reservoir serves to be the cornerstone of geothermal resource exploration and exploitation. Based on the principles and basic train of geothermal reservoir evaluation, in this work, the content of geothermal reservoir evaluation was determined and the value range of geothermal reservoir evaluation parameters was discussed in combination with the actual production data of two types of geothermal reservoir in North China: The Neogene Guantao Formation sandstone pore-type geothermal reservoir, and the Cambrian-Ordovician and Middle Proterozoic Jixian carbonate karst-fissure-type geothermal reservoir. An evaluation method for the sandstone pore-type and the carbonate karst-fissure-type geothermal reservoir is finally established based on the analysis of the production data, i.e. the values of geothermal reservoir temperature, geothermal fluid production, reinjection, physical properties and other parameters are assigned, and the geometric average value of the assigned values for the above-mentioned parameters is taken as the overall evaluation index of geothermal reservoir. From large to small, this index categorizes geothermal reservoir into three grades: I, II and III, which corresponds to advantageous, moderate advantageous and disadvantageous geothermal reservoir respectively. The geothermal reservoir of the same grade are further classified in light of the index value, thus realizing the comprehensive evaluation of geothermal reservoir.

Understanding the origin of natural gas in deep and ultra-deep reservoirs with multiple potential source rocks remains challenging due to the complex thermal evolution of hydrocarbons at high temperatures and multi-stage accumulation processes. This study investigates the origin of natural gas in deep hydrothermal dolomite reservoirs of the Maokou Formation, eastern Sichuan Basin, using hydrocarbon inclusion analysis, radiometric U-Pb dating of calcite cements, maturity modeling of potential source rocks, and constraints on reactivation periods of the nearby No. 15 Fault System. Results indicate an oil charging event at approximately 246.9 Ma, followed by two episodes of gas charging at 222.4 Ma and 175.2 Ma. Furthermore, the oil and gas charging events occurred synchronously with activities of the No. 15 Fault System, suggesting that its reactivation induced episodic hydrocarbon migration. Maturity modeling indicates that during the oil charging period, source rocks in the Qiongzhusi, Wufeng-Longmaxi, and first member of the Maokou formations reached the stages of dry gas generation, significant oil generation, and the threshold of oil generation, respectively. During the subsequent two-episode gas charging periods, the Qiongzhusi and Wufeng-Longmaxi formations progressed to dry and wet gas generation stages, respectively, while the first member of the Maokou Formation attained the oil generation stage. The hydrocarbon charging time and maturity history of potential source rocks indicate that: 1) oil in hydrothermal dolomite reservoirs predominantly originated from the Wufeng-Longmaxi Formation at approximately 246.9 Ma; 2) during the subsequent gas charging episodes, the Wufeng-Longmaxi Formation could contribute wet gas, while the Qiongzhusi Formation likely supplied cracking gas from kerogen and residual liquid hydrocarbon; 3) all oil in the hydrothermal dolomite reservoirs underwent thermal cracking to gas at approximately 110 Ma. This study indicates that gas pools in (ultra-)deep carbonate reservoirs of the Sichuan Basin have mixed genetic origins, with contributions from multiple sources. The multidisciplinary approach, combining direct dating of hydrocarbon charge events and simulation of hydrocarbon generation, proves robust and effective in identifying the origin of natural gas in (ultra-)deep reservoirs.

The necessary conditions for the existence of odd harmonious labelling of graph are obtained. A cycle C n is odd harmonious if and only if n ≡0 (mod 4). A complete graph K n is odd harmonious if and only if n =2. A complete k -partite graph K ( n 1 , n 2 ,…, n k ) is odd harmonious if and only if k =2. A windmill graph K n t is odd harmonious if and only if n =2. The construction ways of odd harmonious graph are given. We prove that the graph ∨ i =1 n G i , the graph G (+ r 1 ,+ r 2 ,…,+ r p ), the graph , the graph G ∪( X +∪ k =1 n Y k ), some trees and the product graph P m × P n etc. are odd harmonious. The odd harmoniousness of graph can be used to solve undetermined equation.

The 1.39km long tunnel in Shouyi Square of Wuhan is situated at the main artery of the city traffic. To ensure smooth construction of this tunnel project, a varieties of supporting systems such as rubble retaining wall, piles and steel supports, cantilever piles, pile-anchors, shotcrete-bolts are adopted. Meanwhile, safety monitoring is carried out using advanced monitoring instruments and methods with emphasis on the key cultural relic of Hubei province Honglou. The influence of the foundation excavation construction on Honglou is informed by analysis of monitoring result and the monitoring prediction provides forceful support for decision-making during the construction. In this way smooth construction of the foundation excavation and safety of Honglou are ensured.

Wavelength Division Networks (WDM) rings is a very attractive network. The key terminating equipments are add-drop multiplexers (ADMs) on the WDM networks. It is essential to find an efficient routing and wavelength assignment to a given set of traffic streams such that the total ADM cost is minimal. In this paper, we will obtain the minimal ADM number A(12,v)=v (v-1)/4 when v≡1,9 (mod 24) and v≥25.

Carbonate cemented zones are normally adjacent to the top overpressured surface in the central Junggar Basin, NW China. Stable carbon and oxygen isotopic compositions and petrological investigations of carbonate cements in the carbonate cemented zones indicate that: (1) carbonate cements are composed dominantly of ferrocalcite, ferroan dolomite, and ankerite; (2) carbonate cements are formed under a high temperature circumstance in the subsurface, and organic fluid migration has an important effect on the formation of them; and (3) carbon and oxygen ions in the carbonate cements migrate from the underlying overpressured system. This suggests that the occurrence of carbonate cemented zones in this region results from multiple phases of organic fluid expulsion out of the overpressure compartment through geological time. This study provides a plausible mechanism of the formation of carbonate cemented zones adjacent to the top overpressured surface in the clastic sedimentary basins, and has an important implication for understanding the internal correlation between the formation of carbonate cemented zones adjacent to top overpressured surface and geofluids expulsion out of overpressured system.

A concise, in-depth introduction to active disturbance rejection control theory for nonlinear systems, with numerical simulations and clearly worked out equations * Provides the fundamental, theoretical foundation for applications of active disturbance rejection control * Features numerical simulations and clearly worked out equations * Highlights the advantages of active disturbance rejection control, including small overshooting, fast convergence, and energy savings