Search Results (1,384)

Compared with conventional gas reservoirs, deep shale gas reservoirs are characterized by developed faults and fractures, strong heterogeneity, high stress sensitivity, and complex in situ stress distribution. To address traditional 3D static models’ inability to predict in situ stress changes in strongly heterogeneous reservoirs during fracturing, this study takes the deep shale gas in the Zigong block of the Sichuan Basin as an example. By comprehensively considering the heterogeneity and anisotropy of geomechanical parameters and natural fractures in shale gas reservoirs, a 4D in situ stress multi-physics coupling model for shale gas reservoirs based on geology–engineering integration is established. Through coupling geomechanical parameters with fracturing operation data, the dynamic evolution laws of multi-scale stress fields from single-stage to platform-scale during large-scale fracturing of horizontal wells in deep shale gas reservoirs are systematically studied. The research results show the following: (1) The fracturing process has a significant impact on the magnitude and direction of the stress field. With the injection of fracturing fluid, both the minimum and maximum horizontal principal stresses increase, with the minimum horizontal principal stress rising by 1.8–6.4 MPa and the maximum horizontal principal stress by 1.1–3.2 MPa; near the wellbore, there is an obvious deflection in the direction of in situ stress. (2) As the number of fracturing stages increases, the minimum horizontal principal stress shows an obvious cumulative growth trend, with a more significant increase in the later stages, and there is a phenomenon of stress accumulation along the wellbore, with the stress difference decreasing from 15 MPa to 11 MPa. (3) The on-site adoption of the fracturing operation method featuring overall flush advancement and inter-well staggered fracture placement has achieved good stress balance; comparative analysis shows that the stress communication degree of the 400 m well spacing is weaker than that of the 300 m well spacing. This study provides a more reasonable simulation method for large-scale fracturing development of deep shale gas, which can more accurately predict and evaluate the dynamic stress field changes during fracturing, thereby guiding fracturing operations in actual production. Full article

The use of single-layer aerated concrete walls in residential construction has a tradition of over 60 years. Its main advantage is thermal insulation. It is the most advantageous among construction materials used for the construction of external walls. The possibility of modifying the dimensions of the blocks leads to meeting subsequent restrictive values of the heat transfer coefficient U. The high dimensional accuracy of the blocks allows the use of dry vertical joints and thin joints with a thickness of 1–3 mm, the thermal influence of which is omitted. However, the thermal uniformity of such a wall is strictly dependent on the quality of workmanship. The main objective of the analysis is to assess the impact of moisture on the U_wall of walls as a function of vertical joint spacing and horizontal joint thickness. It should be said that the effect of humidity and manufacturing accuracy on the thermal properties of aerated concrete walls has not been sufficiently studied. Further study of these patterns is necessary. Particular attention should be paid to the thin-bed mortar, which depends on the manufacturing accuracy. The separation of AAC masonry elements that occurs during bricklaying significantly affects the thermal insulation of walls. This issue has not yet been analysed. The scientific objective of this article is to develop a procedure for determining the thermal properties of a small, irregular air space created as a result of the separation of masonry elements and the impact of this separation on the thermal insulation of the wall. Based on the analysis of the thermal conductivity of voids and masonry elements, it was determined that this impact is visible at low AAC densities. A detailed analysis taking into account both these joints and horizontal joints, as well as different moisture levels, made it possible to determine the permissible separation of AAC blocks, at which the high thermal insulation requirements applicable in most European countries are met. The analysis showed that it is possible to meet the thermal protection requirements for 42 cm wide blocks intended for single-layer walls with a maximum vertical contact width of 3 mm and a joint thickness of up to 2 mm. AAC moisture content plays a major role in thermal insulation. Insulation requirements can be met for AAC in an air-dry state, as specified by ISO 10456. Full article

As an important branch of lanthanide-based complexes, clusters show unique properties in magnetocaloric effect (MCE) and single-molecule magnets (SMMs) using O/N ligands, while research on heavy p-block elements (e.g., S atom) with larger atomic radii and more diffuse p valence orbitals as coordinating atoms remains relatively scarce. Herein, using the sulfur-containing ligand of 2-pyridinethiol 1-oxide (HL), we successfully synthesized a series of hourglass-like Ln₉ clusters [Ln₉(L)₁₇(μ₃-OH)₉(μ₄-OH)]·nH₂O (1: Ln = Gd, n = 3; 2: Ln = Tb, n = 3; 3: Ln = Dy, n = 1). Magnetic data analysis reveals that cluster 1 shows a significant MCE, with the entropy change (−ΔS_m) reaching a maximum of 34.41 J kg⁻¹ K⁻¹ at 2 K under ΔH = 7 T. Cluster 3, meanwhile, exhibits distinct frequency- and temperature-dependent behavior, indicating its SMM characteristics. Interestingly, despite possessing the highest molar mass among reported Gd₉ clusters with MCE, 1 exhibits a competitive −ΔS_m value, highlighting the critical role of sulfur-containing ligand on the structure and even exchange interactions. This work offers new insights into synthesizing high-performance MCE materials and understanding magneto-structural relationships. Full article

High temperature typically decreases feed intake, milk production, and efficiency and increases metabolic disorders and health problems, greatly impacting farm economics. Supplements based on Saccharomyces cerevisiae have been suggested to benefit cows under heat stress, but effects on dairy cow performance are contradictory. This study aimed to evaluate the influence of heat stress on the effects of live yeast supplementation on the performance of dairy cows. Environmental temperature parameters were compared to two thermal humidity indices (THI1 and THI2) using wet bulb or dew point temperatures, as explanatory variables of dairy cow performance during the hot season. The experiment followed a randomized complete block design with 12 Holstein cows blocked by lactation number, days in milk, and milk production (two cows per block) and within each block, each cow was randomly assigned to a maize silage-based TMR with a concentrate mixture containing no yeast culture (Control) or 1 g/kg concentrate dry matter of a live yeast culture based on S. cerevisiae (Yeast) for 35 days. The experiment lasted for 35 d. Dry matter intake (DMI) was significantly higher for Yeast than it was for Control for all classes of temperature and THIs studied with an average increase of 2 kg DM per day, except for mean THI1 (from 54 to 60), for which the DMI was similar between treatments. Yeast promoted significantly higher milk yield than Control for all classes of daily maximum and mean temperature, averaging an increase of 4 kg of milk per day. Results suggest a more marked effect of temperature and indicate that yeast supplementation improved lactation performance of dairy cows exposed to hot weather. Full article

Mules and donkeys are the 5th largest equine population in the U.S., yet basic information such as heart rate and arrhythmia prevalence in mules has not been described. Analysis of heart rate variability (HRV) provides valuable insight into physiologic and autonomic differences between mules, horses, and donkeys. We aimed to pilot the evaluation of heart rate and variability in a healthy population of mules using a 24 h electrocardiogram. Twenty-four-hour ambulatory electrocardiogram (aECG) recordings were collected from an athletic population of seven privately owned healthy mules in Northern California. Vision 5 Holter Analysis Software was utilized for ECG review and analysis. An average heart rate of 32–42 bpm, with a mean of 36 ± 3 bpm for 23.8 ± 0.2 h, was recorded. Minimum heart rate was 16–24 bpm, and maximum was 70–156 bpm. Individual mules had supraventricular complexes, sinoatrial heart block, and second-degree atrioventricular block during the observation period. Electrocardiographic evaluation of mules over 24 h found heart rate (HR) to be similar to horses and lower than in donkeys. Arrhythmias were consistent with the range of cardiac rhythms observed in horses and more frequent than reported in donkeys. Further investigation with a larger sample size of mules is warranted to determine if reference values for horses should continue to be used to assess mules and to investigate the prevalence of arrhythmias and their clinical relevance in the mule. Full article

Aiming at the problems of intensified soil compaction under the conditions of no-tillage operations and machine blockage caused by large-scale straw returning to the field, an operation mode of “straw strip collecting-strip subsoiling” was proposed, and a Monomer Profiling Strip Tillage Machine (MPSTM) with Straw-Strip-Collecting and Subsoiling Functions was designed to achieve anti-blocking operation and three-dimensional soil compaction reduction. The principle and mechanism parameters of monomer profiling in strip tillage are analyzed, and the effective profiling conditions are clarified. It is determined that the deflection angle, inclination angle, and installation spacing have a key influence on the straw clearance effect. The theory of soil failure and soil compaction reduction under the operation of the subsoiling and strip tillage mechanism is studied, and a combination of a medium-sized Subsoiler shovel handle and a 150 mm double-wing shovel is adopted. Using the EDEM discrete element method, taking the spatial parameters of the stubble clean disc (SCD) as the test factors and the straw removal rate (SRR) as the test indicator, a quadratic orthogonal rotation test is conducted to clarify the influence of each parameter on the straw clearance. The optimal SCD spatial parameters were determined as a deflection angle of 16.5°, an inclination angle of 25°, and an installation spacing of 100 mm, achieving a maximum SRR of 95.34%. Field test results demonstrated stable machine operation. Post-operation measurements yielded the following results: the width of the straw-cleaning band (WSCB) in the sowing strip is 193.7 mm; the overall straw removal rate (OSRR) is 84.82%, which is basically consistent with the simulation results; the subsoiling depth (SD) is 271.7 mm; the subsoiling depth stability (SDS) is 91.85%; the soil fragmentation rate (SFR) is 81.19%; and the reduction of soil compaction in the 0–10, 10–20, and 20–30 cm soil layer is 50.08%, 21.78%, and 40.83%, respectively. These results confirm that the machine effectively cleaned straw within the seeding band and reduced soil compaction, meeting the agronomic and technical requirements for strip tillage. Full article

The real-time detection and localization of dynamic targets in cattle farms are crucial for the effective operation of intelligent equipment. To overcome the limitations of wearable devices, including high costs and operational stress, this paper proposes a lightweight, non-contact solution. The goal is to improve the accuracy and efficiency of target localization while reducing the complexity of the system. A novel approach is introduced based on YOLOv8s, incorporating a C2f_DW_StarBlock module. The system fuses binocular images from a ZED2i camera with GPS and IMU data to form a multimodal ranging and localization module. Experimental results demonstrate a 36.03% reduction in model parameters, a 33.45% decrease in computational complexity, and a 38.67% reduction in model size. The maximum ranging error is 4.41%, with localization standard deviations of 1.02 m (longitude) and 1.10 m (latitude). The model is successfully integrated into an ROS system, achieving stable real-time performance. This solution offers the advantages of being lightweight, non-contact, and low-maintenance, providing strong support for intelligent farm management and multi-target monitoring. Full article

During traditional aircraft landings, pilots face significant challenges in identifying runway numbers with the naked eye, particularly at decision height under adverse weather conditions. To address this issue, this study proposes a novel detection algorithm based on an optimized version of the YOLOv5s model (You Only Look Once, version 5) for recognizing runway markings during civil aircraft landings. By integrating a data augmentation strategy with external datasets, the method effectively reduces both false detections and missed targets through expanded feature representation. An Alpha Complete Intersection over Union (CIOU) Loss function is introduced in place of the original CIOU Loss function, offering improved gradient optimization. Additionally, the model incorporates several advanced modules and techniques, including a Convolutional Block Attention Module (CBAM), Soft Non-Maximum Suppression (Soft-NMS), cosine annealing learning rate scheduling, the FReLU activation function, and deformable convolutions into the backbone and neck of the YOLOv5 architecture. To further enhance detection, a specialized small-target detection layer is added to the head of the network and the resolution of feature maps is improved. These enhancements enable better feature extraction and more accurate identification of smaller targets. As a result, the optimized model shows significantly improved recall (R) and precision (P). Experimental results, visualized using custom-developed software, demonstrate that the proposed optimized YOLOv5s model achieved increases of 5.66% in P, 2.99% in R, and 2.74% in mean average precision (mAP) compared to the baseline model. This study provides valuable data and a theoretical foundation to support the accurate visual identification of runway numbers and other reference markings during aircraft landings. Full article

Several approaches to the synthesis of risdiplam, a pharmacologically relevant pyridopyrimidinone derivative, have been recently reported. However, most of these routes rely exclusively on palladium-catalyzed, cross-coupling reactions and involve low-yielding intermediates, which limit their scalability and complicate impurity control. In this work, we present a five-step, straightforward route to risdiplam, utilizing ethyl 2,8-dimethylimidazo[1,2-b]pyridazine-3-carboxylate—an accessible and cost-effective building block previously developed by our research group—as a starting material. The key step involves construction of the 4H-pyrido[1,2-a]pyrimidin-4-one scaffold via a copper(I)-catalyzed heterocyclization reaction. This represents a novel and convenient protocol for the synthesis of 2-(2,8-dimethylimidazo[1,2-b]pyridazin-6-yl)-7-fluoro-4H-pyrido[1,2-a]pyrimidin-4-one, which serves as a crucial intermediate in the final stages of risdiplam synthesis. The overall process allows us to obtain the target compound with a 20% total yield (from abovementioned starting material) and high purity (99.86%, by HPLC-UV), with a maximum level of unidentified impurities not exceeding 0.046%. The developed approach eliminates the use of palladium catalysis and chromatographic purification, offering a practical and scalable alternative for risdiplam production. Full article

To reveal the fracture mechanism of overburden aquifers during mining under anticlinal structural zones in western mining areas, this study takes Panel 1309 of the Guojiahe Coal Mine as the engineering background and employs field investigations, physical similarity simulation, and numerical simulation methods to systematically investigate the overburden fracture and crack evolution laws during extra-thick coal seam mining in anticlinal zones. The research results demonstrate the following: (1) The large slope angle of the anticlinal zone and significant elevation difference between slope initiation points and the axis constitute the primary causes of water inrush-induced support failures in working face 1309. The conglomerate of the Yijun Formation serves as the critical aquifer responsible for water inrush, while the coarse sandstone in the Anding Formation acts as the key aquiclude. (2) Influenced by the slope angle, both overburden fractures and maximum bed separation zones during rise mining predominantly develop toward the goaf side. The water-conducting fracture zone initially extends in the advance direction, when its width is greater than its height, and changes to a height greater than its width when the key aquifer fractures and connects to the main aquifer. (3) The height of the collapse zone of the working face is 65 m, and the distribution of broken rock blocks in the collapse zone is disordered; after the fracture of the water-insulating key layer, the upper rock layer is synchronously fractured and activated, and the water-conducting fissure leads to the water-conducting layer of the Yijun Formation. (4) Compared to the periodic ruptures of the main roof, the number of fractures and their propagation speed are greater during the initial ruptures of each stratum. Notably, the key aquiclude’s fracture triggers synchronous collapse of overlying strata, generating the most extensive and rapidly developing fracture networks. (5) The fracture surface on the mining face side and the overlying strata separation zone jointly form a “saddle-shaped” high-porosity area, whose distribution range shows a positive correlation with the working face advance distance. During the mining process, the porosity variation in the key aquiclude undergoes three distinct phases with advancing distance: first remaining stable, then increasing, and finally decreasing, with porosity reaching its peak when the key stratum fractures upon attaining its ultimate caving interval. Full article

The increasing interest shared by academia and industry in the development of RISC-V cores, extensions and accelerators becomes fructified by collaborative efforts, like the EU’s ChipsJU, which leverages the design of building blocks, IPs and cores based on RISC-V architecture. A domain capable of benefiting from the RISC-V extensibility is the control of external DACs and ADCs. The proposed solution is an open-source RISC-V extension for optimized control of external DACs and ADCs called RiscADA. The extension supports a parametrizable number of DACs and ADCs, is integrated as a coprocessor beside CVA6 in a SoC by using the CV-X-IF interface, deployed on a Kintex UltraScale+ FPGA and implements ISA extension instructions. After benchmarks with commercial solutions, the results show that CVA6 using RiscADA extension configures external DACs 38.6× and 10.9× times faster than MicroBlaze V and simple CVA6, both using AXI SPI peripherals. The proposed extension achieves 5.35× and 3.05× times higher sample rates of external ADCs than the two configurations mentioned above. RiscADA extension performs digital signal conditioning 4.52× and 3.1× times faster than the MicroBlaze V and CVA6, both using AXI SPI peripherals. It computes statistics for external ADC readings (minimum, maximum, simple-moving average and over-threshold duration). Full article

Background: Despite the survival benefit of ICDs in patients with HFrEF, most recipients do not receive appropriate therapy during follow-up. Existing risk models based on echocardiographic and clinical parameters show limited predictive accuracy for arrhythmic events. This study aimed to assess whether ECG-derived markers outperform conventional measures in predicting appropriate ICD shocks. Methods: This retrospective observational study included 375 patients with HFrEF who underwent ICD implantation for primary prevention at least six months before study enrollment. Twelve-lead surface ECGs were analyzed for a QTc interval, Tp-e/QT ratio, frontal QRS-T angle, and maximum deflection index (MDI). Clinical, echocardiographic, and arrhythmic event data obtained from device interrogations were evaluated. Receiver operating characteristic (ROC) curve analysis and multivariate logistic regression were performed to identify independent predictors of appropriate ICD shocks. Results: Patients who experienced appropriate ICD shocks had significantly higher rates of a complete bundle branch block, digoxin use, QRS duration, QTc, Tp-e/QT ratio, frontal QRS-T angle, MDI, and right-ventricular pacing ratio. Conversely, beta-blocker use was significantly lower in this group. In multivariate analysis, independent predictors of appropriate shocks included the patient’s digoxin use (OR = 2.931, p = 0.003), beta-blocker use (OR = 0.275, p = 0.002), frontal QRS-T angle (OR = 1.009, p < 0.001), QTc interval (OR = 1.020, p < 0.001), and Tp-e/QT ratio (OR = 4.882, p = 0.050). The frontal QRS-T angle had a cutoff value of 105.5° for predicting appropriate ICD shocks (sensitivity: 73.6%, specificity: 85.2%, AUC = 0.758, p < 0.001). Conclusions: Electrocardiographic markers, particularly the frontal QRS-T angle, QTc interval, and Tp-e/QT ratio, demonstrated superior predictive power for appropriate ICD shocks compared to conventional echocardiographic and clinical measures. These easily obtainable, non-invasive ECG parameters may improve current risk stratification models and support more individualized ICD implantation strategies. Full article

This study investigates a novel heat pipe integrated cooling system designed for thermal management of Tesla’s 4680 cylindrical lithium–ion batteries in electric vehicles (EVs). Through a comprehensive approach combining experimental analysis, 1-D AMESim simulations, and 3-D Computational Fluid Dynamics (CFD) modeling, the thermal performance of various wick structures and working fluid filling ratios was evaluated. The experimental setup utilized a triangular prism chamber housing three surrogate heater blocks to replicate the heat generation of 4680 cells under 1C, 2C, and 3C discharge rates. Results demonstrated that a blended fabric wick with a crown-shaped design (Wick 5) at a 30–40% filling ratio achieved the lowest maximum temperature (T_max of 47.0 °C), minimal surface temperature deviation (ΔT_surface of 2.8 °C), and optimal thermal resistance (R_th of 0.27 °C/W) under 85 W heat input. CFD simulations validated experimental findings, confirming stable evaporation–condensation circulation at a 40% filling ratio, while identifying thermal limits at high heat loads (155 W). The proposed hybrid battery thermal management system (BTMS) offers significant potential for enhancing the performance and safety of high-energy density EV batteries. This research provides a foundation for optimizing thermal management in next-generation electric vehicles. Full article

In this work, we demonstrate high-efficiency 385 nm AlGaN-based near-ultraviolet micro light emitting diode (NUV-Micro LED) arrays. The epi structure is prepared using a novel AlN-inserted superlattice electrical blocking layer which enhances hole spreading in the p-type region significantly. The NUV-Micro LED arrays in this work comprise 228 chips in parallel with wavelengths at 385 nm, and each single chip size is 15 × 30 μm². Compared with conventional bulk AlGaN-based EBL structures, the NUV-Micro LED arrays that implemented the new hole spreading enhanced superlattice electrical blocking layer (HSESL-EBL) structure proposed in this work had a remarkable increase in light output power (LOP) at current density, increasing the range down from 0.02 A/cm² to as high as 97 A/cm². The array’s light output power is increased up to 1540% at the lowest current density 0.02 A/cm², and up to 58% at the highest current density 97 A/cm², measured under room temperature (RT); consequently, the WPE is increased from 13.4% to a maximum of 30.18%. This AlN-inserted HESEL-EBL design significantly enhances both the lateral expansion efficiency and the hole injection efficiency into the multi quantum well (MQW) in the arrays, improving the concentration distribution of the holes in MQW while maintaining good suppression of electron leakage. The array’s efficiency droop has also been greatly reduced. Full article

The aim of this study was to improve the efficiency of in situ uranium leaching by developing a specialized methodology for selecting rational parameters for the chemical treatment of production wells. This approach was designed to enhance the filtration properties of ores and extend the uninterrupted operation period of wells, considering the clay content of the productive horizon, the geological characteristics of the ore-bearing layer, and the composition of precipitation-forming materials. The mineralogical characteristics of ore and precipitate samples formed during the in situ leaching of uranium under various mining and geological conditions at a uranium deposit in the Syrdarya depression were identified using an X-ray diffraction analysis. It was established that ores of the Santonian stage are relatively homogeneous and consist mainly of quartz. During well operation, the precipitates formed are predominantly gypsum, which has little impact on the filtration properties of the ore. Ores of the Maastrichtian stage are less homogeneous and mainly composed of quartz and smectite, with minor amounts of potassium feldspar and kaolinite. The leaching of these ores results in the formation of gypsum with quartz impurities, which gradually reduces the filtration properties of the ore. Ores of the Campanian stage are heterogeneous, consisting mainly of quartz with varying proportions of clay minerals and gypsum. The leaching of these ores generates a variety of precipitates that significantly reduce the filtration properties of the productive horizon. Effective compositions and concentrations of decolmatant (clog removal) solutions were selected under laboratory conditions using a specially developed methodology and a TESCAN MIRA scanning electron microscope. Based on a scanning electron microscope analysis of the samples, the effectiveness of a decolmatizing solution based on hydrochloric and hydrofluoric acids (taking into account the concentration of the acids in the solution) was established for the destruction of precipitate formation during the in situ leaching of uranium. Geological blocks were ranked by their clay content to select rational parameters of decolmatant solutions for the efficient enhancement of ore filtration properties and the prevention of precipitation formation. Pilot-scale testing of the selected decolmatant parameters under various mining and geological conditions allowed the optimal chemical treatment parameters to be determined based on the clay content and the composition of precipitates in the productive horizon. An analysis of pilot well trials using the new approach showed an increase in the uninterrupted operational period of wells by 30%–40% under average mineral acid concentrations and by 25%–45% under maximum concentrations with surfactant additives in complex geological settings. As a result, an effective methodology for ranking geological blocks based on their ore clay content and precipitate composition was developed to determine the rational parameters of decolmatant solutions, enabling a maximized filtration performance and an extended well service life. This makes it possible to reduce the operating costs of extraction, control the geotechnological parameters of uranium well mining, and improve the efficiency of the in situ leaching of uranium under complex mining and geological conditions. Additionally, the approach increases the environmental and operational safety during uranium ore leaching intensification. Full article