Search Results (122)

Differential planetary roller lead screw (DPRS) serves as a quintessential actuating mechanism within the electromechanical braking (EMB) systems of vehicles, where its operational reliability is paramount to ensuring braking safety. Considering different braking intensities, how assembly errors affect the contact stress in DPRS was analyzed via the finite element method. Firstly, the braking force of the EMB system that employed DPRS was verified by the braking performance of legal provisions. Secondly, a rigid body dynamics model of DPRS was established to analyze the response time, braking clamping force, and axial contact force of DPRS under varied braking intensities. Finally, a finite element model of DPRS was constructed. The impact of assembly errors in the lead screw and rollers on the contact stress were investigated within the DPRS mechanism based on this model. The results indicate that as braking intensity increases, the deviation of the lead screw exerts a greater influence on the contact stress generated by the engagement between the lead screw and rollers compared to that between the nut and rollers. The skewness of the rollers also affects the contact stress generated by the engagement of both the lead screw with rollers and the nut with rollers. When assembly errors reach a certain threshold, the equivalent plastic strain is induced to exceed the critical value. This situation significantly impairing the normal operation of DPRS. This study provides guidance for setting the threshold of assembly errors in DPRS mechanisms. It also holds significant implications for the operational reliability of EMB systems. Full article

The accuracy and speed of tomato detection were increased to facilitate fully automated harvesting by improving the Real-Time Detection Transformer (RTDETR) to develop a new lightweight tomato detection model called LiteTom-RTDETR. This model employed RepViT as a lightweight backbone network instead of the original RTDETR backbone, considerably reducing both the number of parameters in and computational complexity of the model. Furthermore, a context guide fusion module was designed to enhance multiscale feature extraction efficiency, and an adaptive sliding weight mechanism was integrated into the loss function to mitigate class-imbalance issues. The proposed LiteTom-RTDETR model was shown to balance high tomato identification accuracy (88.2%) with an excellent real-time inference speed (52.2 frames per second) and computational efficiency (36.3 GFLOPs). Notably, the average detection accuracy of LiteTom-RTDETR was 0.6% higher, its detection speed was 15.5% faster, and its computational load and model size were 36.2% and 31.6% smaller, respectively, than those of the original RTDETR model. Therefore, the proposed model provides a practical approach for realizing visual recognition tasks in resource-constrained mobile automated tomato harvesting equipment. Full article

Jet fuel from direct coal liquefaction (DCL) is an important alternative kerosene and represents a high-performance fuel for specific applications in civil applications. The study on its chemical positions and combustion properties is critical for the development of surrogate models and related combustion reaction mechanisms, which is valuable for promoting its usage in aeroengines. However, research on DCL-derived jet fuel is rather scarce. Herein, this work reports a systematic study on a DCL-derived jet fuel and its blends with traditional RP-3 jet fuel in two different ratios. Specifically, major physicochemical properties related to the aviation fuel airworthiness certification process are measured. Advanced two-dimensional gas chromatography (GC × GC) analysis is used to analyze the detailed chemical compositions on the DCL derived jet fuel and its blend with RP-3, which is then employed for surrogate model development. Moreover, ignition delay times (IDTs) are measured by using a heated shock-tube (ST) facility for the blended fuels over a wide range of conditions. Combustion reaction mechanisms based on the surrogate models are developed to predict the experimental measured IDTs. Finally, sensitivity analysis and rate-of-production analysis are carried out to identify the key chemical kinetics controlling the ignition characteristics. This work extends the understanding of the physicochemical properties and ignition characteristics of alternative jet fuels and should be valuable for the practical usage of DCL derived jet fuels. Full article

The functionality of unmanned aerial vehicles (UAVs) in agricultural applications was improved by optimizing the parameters of the vector bracket in a vertical takeoff and landing UAV to maximize thrust and lift-to-drag ratio. First, the results of computational fluid dynamics simulations were compared with wind tunnel data to ensure an accurate model of the considered UAV, indicating a thrust coefficient error of less than 3% and a UAV lift-to-drag ratio error of less than 8%. Next, this model was applied to simulate the propeller thrust and UAV lift-to-drag ratio for 25 sample points selected using a central composite experimental design by varying the four structural parameters of the vector bracket. A kriging algorithm was subsequently applied to construct response surface models based on the results. Finally, a Multi-Objective Genetic Algorithm was employed to determine the optimal parameter values maximizing the two coefficients. The optimal structural parameters for the UAV vector bracket were determined to comprise a vector bracket height of 51 mm, fixed bracket length of 168 mm, fixed bracket width of 69 mm, and ball socket outer diameter of 31 mm. These values provided a 19% larger propeller thrust coefficient than those of the original UAV. Full article

Background: Esophagogastroduodenoscopy (EGD) is essential for diagnosing upper gastrointestinal disorders. Traditional training for novice endoscopists is often inefficient and inconsistent. This study evaluates the effectiveness of an AI-assisted system (EndoAdd) in improving EGD training. Methods: In a randomized controlled trial, eight novice endoscopists were assigned to either the EndoAdd group or a control group (traditional training). The EndoAdd system provided real-time feedback on blind spots and photodocumentation. Primary outcomes were the number of blind spots, with secondary outcomes including examination time, lesion detection, and photodocumentation completeness. Results: The EndoAdd system exhibited an overall accuracy of 98.0% and a mean area under the curve (AUC) of 0.984. The EndoAdd group had significantly fewer blind spots, improved photodocumentation, and a higher lesion detection rate. Examination time was reduced without compromising diagnostic accuracy. Conclusions: The AI-assisted EndoAdd system improved novice endoscopist performance, reducing blind spots and enhancing lesion detection. AI systems like EndoAdd show potential in accelerating endoscopy training and improving procedural quality. Full article

We report the synthesis, structural characterization, and magnetic properties of three pentacoordinate Co(II) complexes [CoX(dppb)₂]X (X = Cl (1Cl), Br (2Br), and I (3I)) supported by the bidentate phosphine ligand 1,2-bis(diphenylphosphino)benzene (dppb). Single-crystal X-ray diffraction reveals that all three complexes adopt similar vacant octahedron (C_4v) geometries with the halide ligand in one axial position. Magnetic studies demonstrate that these complexes exhibit field-induced slow magnetic relaxation behaviors, with positive D values of 25.3(2), 21.6(1), and 19.4(2) cm⁻¹ for 1Cl, 2Br, and 3I, respectively. Detailed analysis of the relaxation dynamics reveals that Raman processes dominate at higher temperatures, with systematic variations in relaxation parameters across the series. The systematic variations in magnetic anisotropy and slow magnetic relaxation behaviors of the three complexes correlate with the decreasing electronegativity of the halide ligands. Full article

This paper reports a comparative study on the high temperature pyrolysis characteristics of three C₉H₁₂ isomers, including n-propylbenzene (PBZ), 1,3,5-trimethylbenzene (T135MBZ), and 1,2,4-trimethylbenzene (T124MBZ), via single-pulse shock tube (SPST) experiments and kinetic simulations. The SPST experiments were conducted in the temperature range of 1100–1700 K, at pressures of 10 bar and 15 bar, with a fixed fuel concentration of 200 ppm. The reaction time was approximately 1.8 ms for all of the experiments. The distributions of the pyrolysis products were quantitatively analyzed as functions of pressure and temperature. A detailed kinetic mechanism was used to simulate the experimental results, and it is demonstrated that the mechanism can capture the pyrolysis characteristics reasonably well. Both experimental and simulation results reveal that PBZ exhibits higher fuel reactivity than T124MBZ and T135MBZ under the studied conditions. Pyrolysis of all three C₉H₁₂ isomers generates key soot precursors, including acetylene and benzene. Sensitivity and rate-of-production (ROP) analyses indicate similar primary pyrolysis pathways. The benzyl radical is first formed through the dehydrogenation reaction and then it undergoes a series of decomposition reactions leading to the detected small hydrocarbon species. This study not only provides an in-depth understanding of the high temperature pyrolysis characteristics of the three C₉H₁₂ isomers, but also provides essential validation data for the development and optimization of chemical kinetic mechanisms for alkyl aromatic hydrocarbons. Full article

Reducing anthropogenic fossil fuel CO₂ (FFCO₂) emissions in urban areas is key to mitigating climate change. To better understand the spatial characteristics and temporal variations in urban CO₂ levels in the Beijing (BJ) region, we conducted a long-term CO₂ simulation study by using the Weather Research and Forecasting WRF-Chem model and CO₂ observation data. To assess the model performance, three representative sites with high-precision CO₂ observation data were chosen in this study: the rural regional background Shangdianzi (SDZ) site, the suburban Xianghe (XH) site, and the urban BJ site. The simulation results generally captured the observed variations at these three sites, but the model performed much better at the SDZ and XH sites, with mean biases of −0.7 ppm and −2.3 ppm, respectively, and RMSE of 12.3 ppm and 21.4 ppm, respectively. The diurnal variations in the model results agreed well with those in the observed CO₂ concentrations at the SDZ and XH sites during all seasons. In the meanwhile, the diurnal variations in the modeled FFCO₂ were similar to those in the CO₂ observation with a positive bias at the BJ site, which may have been caused by higher emissions especially in winter. Moreover, both the modeled FFCO₂ and biospheric CO₂ (BIOCO₂) have positive correlations with the observed CO₂ concentration, whereas the planetary boundary layer height (PBLH) and observed CO₂ concentration exhibited negative correlations at all sites. In addition, the contributions of FFCO₂ and BIOCO₂ to CO₂ varies depending on the seasons and the location of sites. Full article

As a critical intervention for enhancing inland navigation efficiency, waterway regulation projects profoundly modify riverine hydrodynamic conditions while optimizing navigability. This study employs the MIKE21 hydrodynamic model to establish a two-dimensional numerical framework for assessing hydrological alterations induced by channel regulation in the Hui River, China. Through comparative simulations of pre- and post-project scenarios across dry, normal, and wet hydrological years, the research quantifies impacts on water levels, flow velocity distribution, and geomorphic stability. Results reveal that channel dredging and realignment reduced upstream water levels by up to 0.26 m during drought conditions, while concentrating flow velocities in the main channel by 0.5 m/s. However, localized hydrodynamic restructuring triggered bank erosion risks at cut-off bends and sedimentation in anchorage basins. The integrated analysis demonstrates that although regulation measures enhance flood conveyance and navigation capacity, they disrupt sediment transport equilibrium, destabilize riparian ecosystems, and compromise hydrological monitoring consistency. To mitigate these trade-offs, the study proposes design optimizations—including ecological revetments and adaptive dredging strategies—coupled with enhanced hydrodynamic monitoring and riparian habitat restoration. These findings provide a scientific foundation for balancing navigation improvements with the sustainable management of fluvial systems. Full article

Multi-objective optimization is a cornerstone of modern engineering and management, tackling challenges in complex system design, resource allocation, and financial portfolio optimization. Effective multi-objective optimization algorithms must strike a balance between convergence and diversity, a process that inherently reflects the symmetry in objectives and their trade-offs. However, real-world complexities introduce significant hurdles: the exponential increase in Pareto optimal solutions diminishes the effectiveness of dominance-based selection, while escalating problem complexity heightens the tension between convergence and diversity. To address these issues, we propose a two-archive evolutionary algorithm that integrates reference vectors and a novel hypervolume contribution strategy. This approach employs two complementary archives—convergence and diversity—for parallel optimization. Within the diversity archive, candidate solutions are first filtered using angular relationships to maintain uniform distribution. A novel hypervolume contribution evaluation strategy (HVindex) then determines whether updating solutions can improve the overall quality of the neighborhood population. For the convergence archive, we first select all the non-dominated solutions through non-dominated sorting. These solutions are further refined using reference vectors, and the final archive is completed by adding some opposite characteristic solutions based on distance measurements. The experimental results demonstrate that the proposed algorithm outperforms existing methods in multi-objective optimization. Full article

The combined application of single-cell RNA sequencing (scRNA-seq) and single-cell B-cell receptor sequencing (scBCR-seq) offers a multidimensional perspective for dissecting the immunopathological mechanisms of B cells in autoimmune diseases. This review systematically summarizes the principles of these techniques, the analytical framework, and their key applications in diseases such as systemic lupus erythematosus et. al. It reveals the dynamic correlations between the transcriptome of B-cell subsets and B-cell receptor (BCR) clones. Furthermore, we focus on the potential roles of dual BCR B cells and B/T biphenotypic cells in autoimmunity, emphasizing their exacerbation of disease progression through abnormal clonal expansion and autoantibody secretion. By sorting through cutting-edge advancements and bottleneck issues, this article aims to propel the innovation of multi-omics research and precision treatment paradigms for autoimmune diseases. Full article

Peritoneal dialysis (PD) is a vital treatment for end-stage renal disease patients, but its efficacy is often compromised by complications such as infections and peritoneal fibrosis. Biological field-effect transistors (BioFETs) present a promising solution for rapid, sensitive, and non-invasive detection of indicators and biomarkers associated with these complications, potentially enabling early intervention. However, BioFETs are yet to be adopted for PD monitoring. This review presents a forward-looking analysis of the capacity and potential integration of BioFETs into PD management systems, highlighting their capacity to monitor both routine indicators of dialysis efficiency and metabolic status, as well as specific biomarkers for complications such as inflammation and fibrosis. We examine the challenges in adapting BioFETs for PD applications, focusing on key areas for improvement, including sensitivity, specificity, stability, reusability, and clinical integration. Furthermore, we discuss various approaches to address these challenges, which are crucial for developing point-of-care (PoC) and multiplexed wearable devices. These advancements could facilitate continuous, precise, and user-friendly monitoring, potentially revolutionizing PD complication management and enhancing patient care. Full article

Antiretroviral therapy (ART) can effectively suppress the replication of human immunodeficiency virus (HIV), but it cannot completely eradicate the virus. The persistent existence of the HIV reservoir is a major obstacle in the quest for a cure. To date, there have been a total of seven cured cases of HIV worldwide. These patients all cleared HIV while undergoing allogeneic stem cell transplantation (allo-HSCT) for hematological malignancies. However, in these cases, the specific mechanism by which allo-HSCT leads to the eradication of HIV remains unclear, so it is necessary to conduct an in-depth analysis. Due to the difficulty in obtaining donors and the risks associated with transplantation, this treatment method is not applicable to all HIV patients. There is still a need to explore new treatment strategies. In recent years, emerging therapies such as neutralizing antibody immunotherapy, chimeric antigen receptor T cell (CAR-T) therapy, gene editing, and antiviral therapies targeting the reservoir have attracted wide attention due to their ability to effectively inhibit HIV replication. This article first elaborates on the nature of the HIV reservoir, then deeply explores the treatment modalities and potential success factors of HIV cured cases, and finally discusses the current novel treatment methods, hoping to provide comprehensive and feasible strategies for achieving the cure of HIV. Full article

Maintaining the normal biological rhythms of livestock is of great significance for reflecting the environmental suitability and welfare level of animals. Mistimed feeding can interfere with the circadian rhythms of both humans and animals, resulting in disorders of lipid metabolism, obesity, and metabolic syndrome. Low-temperature environment stimulates increased appetite and decreased physical activity, resulting in higher energy intake than consumption and thus facilitating fat deposition and even obesity. In this study, growing rabbits were randomly allocated to the daytime feeding (DF) group and nighttime restricted feeding (NRF) group. Our research demonstrated that, during winter, the DF regimen disrupted the behavioral rhythms of rabbits and accelerated weight gain without changing overall feed intake. The underlying reason was that DF disturbed the lipid metabolism rhythms, promoted hepatic lipid synthesis regulated by DGAT1 and lipid synthesis of adipose tissues regulated by GPAM, thus triggering fat deposition. In contrast, the NRF regimen enhanced thermogenesis regulated by T3 and elevated body temperature and facilitated ketogenesis mediated by HMGCS2, increasing energy consumption. However, it had no significant impact on the fat content within muscle. This study offers a theoretical foundation for the refinement of feeding management and healthy raising of rabbits. Full article

The issue of fluid loss in fractured formations presents a significant challenge in petroleum engineering, often leading to increased operational costs and construction risks. To address the limitations of traditional lost circulation materials (LCMs) in oil reservoirs with different fracture sizes, this study developed an acrylic resin gel particle with excellent thermal stability (thermal decomposition temperature up to 314 °C) and compatibility. By employing Box–Behnken design and response surface methodology, the synergistic interaction of calcium hydroxide (Ca(OH)₂), asbestos fibers, and cement was optimized to create a novel gel solidification plugging system that meets the requirements of fluid loss control and compressive strength improvement. Experimental results revealed that the gel-based system demonstrated exceptional performance, achieving rapid fluid loss (total fluid loss time of 18~47 s) and forming a high-strength gelled filter cake (24 h compressive strength up to 17.5 MPa). Under simulated conditions (150 °C), the gel-based system provided efficient fracture sealing, showcasing remarkable adaptability and potential for engineering applications. This study underscores the promise of acrylic resin gel particles in overcoming fluid loss challenges in complex fractured formations. Full article