Search Results (169)

This article presents a new full-bridge converter with two series-connected transformers (TTFB), designed to meet the hold-up time requirements in power systems. The conventional TTFB topology offers low root mean square (RMS) output current, clamped voltage stress across the primary switches, and zero-voltage switching (ZVS) capability. However, under a wide input voltage range, it suffers from a significant circulating current during the freewheeling period, leading to efficiency degradation. To mitigate this issue, a new converter is proposed by integrating the TTFB with a boost circuit, which operates during the hold-up state when the input voltage drops below the nominal level. Thus, the proposed converter can increase the duty ratio under nominal input voltage conditions, thereby reducing the primary-side RMS current and improving efficiency. To validate the effectiveness of the proposed method, a prototype with a 12 V/400 W output was implemented. The proposed converter achieved a peak efficiency of 92.1% at 50% load, and maintained a higher efficiency across the entire load range compared to the conventional design. Thus, the proposed converter offers a solution for applications demanding extended hold-up time with improved efficiency. Full article

Post-traumatic stress disorder (PTSD) has traditionally been viewed as a psychiatric disorder of fear, memory, and emotional regulation. However, growing evidence implicates systemic and neuroinflammation as key contributors. Individuals with PTSD often exhibit elevated blood levels of pro-inflammatory cytokines such as IL-1β, IL-6, TNF-α, and C-reactive protein, indicating immune dysregulation. Dysfunctions in the hypothalamic–pituitary–adrenal (HPA) axis marked by reduced cortisol levels impair the body’s ability to regulate inflammation, allowing persistent immune activation. Circulating cytokines cross a weakened blood–brain barrier and activate microglia, which release additional inflammatory mediators. This neuroinflammatory loop can damage brain circuits critical to emotion processing including the hippocampus, amygdala, and prefrontal cortex, and disrupt neurotransmitter systems like serotonin and glutamate, potentially explaining PTSD symptoms such as hyperarousal and persistent fear memories. Rodent models of PTSD show similar inflammatory profiles, reinforcing the role of neuroinflammation in disease pathology. Bromo-epi-androsterone (BEA), a synthetic analog of dehydroepiandrosterone (DHEA), has shown potent anti-inflammatory effects in clinical trials, significantly reducing IL-1β, IL-6, and TNF-α. By modulating immune activity, BEA represents a promising candidate for mitigating neuroinflammation and its downstream effects in PTSD. These findings support the rationale for initiating clinical trials of BEA as a novel therapeutic intervention for PTSD. Full article

This paper presents a novel analytical model of a double-stator single-rotor (DSSR) ironless axial flux machine (IAFM), with no iron either in the rotor or in the stator, that has cylindrical magnets in the rotor. The model is based on sizing equations that include the peak no-load flux density as a determining parameter, and then static simulations using the finite element method show that the 3D magnetic field created by cylindrical magnets can be generally fitted with an empirical function. The analytical model is validated throughout this work with finite element simulations and experiments over a prototype, showing a good agreement. It is stated that the integration of the magnetic field for different rotor positions, using the empirical approach presented here, gives accurate results regarding the back-electromotive force waveform and harmonics, with a reduced computation time and effort compared to the finite element method and avoiding complex formulations of previous analytical models. Moreover, this straightforward approach facilitates the design and comparison of IAFMs with other machine topologies, as sizing equations and magnetic circuits developed for conventional electrical machines are not valid for IAFMs, because, here, the magnetic field circulates entirely through air due to the absence of ferromagnetic materials. Furthermore, the scope of this paper is limited to a DSSR-IAFM, but the method can be directly applied to single-sided IAFMs and could be refined to deal with single-stator double-rotor IAFMs. Full article

This paper investigates the dependencies between the design parameters of the armature (stator) winding of a high-speed PMSM machine and the electrical losses in its windings resulting from eddy currents. In addition, the factors accounting for the occurrence of parasitic circulating currents, whose presence in the phase windings is associated with the design specificity, are analyzed. Quantitative analysis is carried out by the application of a newly developed mathematical model for the calculation of fundamental and additional losses in a multi-turn coil enclosed in the slots of a ferromagnetic core. The analysis takes into account the actual design of the slot and the conductor, the variable arrangement of individual conductors in the slot, the core saturation and the presence of the excitation field—to represent the main factors that affect the process of additional losses in the slot of the electric machine. The verification of the mathematical model developed in this study was carried out by comparing the distribution of power losses in the slot section of the coil, consisting of several elementary conductors connected in parallel and located in a rectangular open slot, with an identical distribution derived on the basis of an analytical method from the classical circuit theory. For the purpose of confirming the results and conclusions derived from simulation studies, a number of physical experiments were carried out, consisting in determining the power losses in multi-turn coils of different designs. Recommendations have been developed to minimize additional losses by optimizing the arrangement of conductors within the slot, selecting the appropriate cross-sectional size of a single conductor and the saturation level of the tooth zone. Full article

The guessing number of a digraph is a new invariant in graph theory raised by S. Riis in 2006 and based on its applications in network coding and boolean circuit complexity theory. In this paper, we present the lower and upper bounds on a guessing number and linear guessing number of circulant digraphs by using cyclic codes. As an application of the lower bound, we construct a series of circulant digraphs with a larger linear guessing number and smaller degree. All of these circulant digraphs provide negative answers to S. Riis’ two open problems on the guessing number proposed in [Proceedings of the 2006 4th International Symposium on Modeling and Optimization in Mobile]. We also give a method to construct circulant digraphs with good estimation on their (linear) guessing number from cyclic codes. Full article

Topological photonic crystals have garnered significant attention due to their fascinating topological edge states. These states are robust against sharp bends and defects and exhibit the novel property of unidirectional transmission. In this study, we analyze the topological edge states of gyromagnetic topological photonic crystals in analogy with the quantum Hall effect. Through expanding and shrinking six dielectric cylinders, the optical quantum spin Hall effect is achieved. And helical edge states with pseudo-spin are demonstrated. Owing to the novel topological properties of these edge states, robust waveguides are proposed. Furthermore, integrating these two distinct types of topological states, a novel circulator with topological characteristics is designed. These topologically protected photonic devices will be beneficial for developing integrated circuits. Full article

To enhance the performance of the combined high-pressure grinding roller (HPGR) and tower mill (TM) process for −1 mm particle size, this study addresses the key technical challenges of insufficient material quantity (<100 kg) and complex experimental procedures in HPGR closed-circuit crushing tests by proposing a novel circulating load prediction method based on the principle of mass balance and first-order crushing kinetics. Using a side-flanged HPGR WGM 6020 installation, systematic −1 mm HPGR closed-circuit crushing tests were conducted on seven different ore samples under three specific pressing forces, with detailed characterization of the dynamic variations in product size distribution, specific energy consumption, and circulating load during each cycle. The results demonstrate that within the specific pressing force range of 3.5 N/mm² to 4.5 N/mm² when the crushing process reaches equilibrium, the circulating load stabilizes between 100% and 200%, while the specific energy consumption is maintained within 1–2.5 kWh/t. Notably, at the specific pressing force of 4.5 N/mm², both the circulating load and specific energy consumption rapidly achieve stable states, with ore characteristics showing no significant influence on the number of cycles. To validate the model accuracy, additional samples were tested for comparative analysis, revealing that the deviations between the model-predicted −1 mm product content and circulating load and the experimental results were less than ±5%, confirming the reliability of the proposed method. Full article

The Southwest Alpine Canyon Area (SACA) is a typical ecologically sensitive location in China; therefore, constructing and optimizing an ecological network for this area is essential to ensure the regional ecological security of its fragile ecosystems. This study employed the InVEST model to quantitatively assess the habitat quality of the SACA for the years 2000, 2010, and 2020. The ecological sources were determined based on the results of a habitat quality assessment and a Morphological Spatial Pattern Analysis (MSPA). Finally, ecological corridors, ecological pinch points, and ecological barrier points were identified using circuit theory. The results indicated that the SACA’s habitat quality was relatively good, but experienced slight degradation from 0.87 in 2000 to 0.84 in 2020. Anthropogenic activities have been identified as the primary contributor to habitat quality decline in the region. Geographically, the habitat quality is significantly poorer in the southeast and northwest of the SACA. A total of 319 ecological sources were identified, predominantly located in the southwest and northeast of the SACA, comprising 43.27% of the total area. Furthermore, 94 ecological corridors were delineated, covering an area of 74,015.61 km² and extending over 182.80 km in length in total. A total of 38 ecological pinch points and 39 ecological barrier points were distinguished, with a noticeable concentration in regions undergoing ecological degradation. Overall, while the ecological network structure in the SACA is complex and highly interconnected, it faces challenges relating to material cycling and ecological network circulation. Future ecological restoration and protection efforts should focus on areas along the border between the ecological maintenance area in southeastern Tibet (Region I) and the water conservation area in eastern Tibet–western Sichuan (Region II). Additionally, the establishment of ecological protection belts around potential ecological corridors is proposed to enhance ecosystem connectivity. These findings could provide a robust scientific foundation for territorial spatial planning, ecological preservation, and restoration in the SACA. Full article

Staged palliation with the creation of a Fontan circulation is the standard surgical approach in patients with a single ventricle. The Fontan circulation is a complex circuit that is associated with various complications that may present early or later in life and can limit life quality and expectancy. In this context, a good understanding of the Fontan physiology is important to improve outcomes for single-ventricle patients. Cardiovascular magnetic resonance (CMR) is recommended for the long-term follow-up of Fontan patients, as it provides functional and haemodynamic information. Four-dimensional (4D) Flow MRI is a time-resolved, three-dimensional, velocity-encoded cardiovascular magnetic resonance technique that is increasingly used in Fontan patients because it not only enables measuring blood flow within a three-dimensional (3D) volume, but also allows for assessing more advanced haemodynamic parameters that may help in understanding the Fontan physiology and pathophysiology. Furthermore, 4D Flow is used for image-based simulations using computational fluid dynamics. In this review, we provide an overview of the use of cardiovascular magnetic resonance flow assessment, with a focus on four-dimensional flow (‘4D Flow’). Full article

In this study, in order to overcome the limitations of existing electric vehicle (EV) thermal management systems (TMS), a highly integrated and coordinated operation strategy for EV thermal management was proposed. Specifically, an integrated architecture with a 10-way valve was established to replace traditional 3-way and 4-way valves to enhance the coupling between coolant circuits. Six operating modes were realized via the switching function of the 10-way valve, including the mode of waste heat recovery. A highly integrated TMS model was developed on the AMEsim2304 platform, followed by parameter matching. The accuracy of the model was validated through comparative analysis with laboratory and environmental chamber test results. Based on the designed highly integrated TMS, a classical fuzzy Proportional-Integral-Derivative Control (PID) control strategy was introduced to regulate the coolant circulation pump. Simulation analyses and experimental results demonstrated that the optimized system could reduce the battery pack heating time by approximately 300 s compared to the pre-optimized configuration. Moreover, the waste heat recovery could improve the cabin heating rate from 1.9 °C/min to 3.4 °C/min, representing a 43.7% enhancement. Furthermore, the output power of the high-pressure liquid heater remained low, resulting in a 10% reduction in overall heating energy consumption. Based on simulation and experimental analyses, this research can promote the progress of thermal management system technology for electric vehicles to a certain extent. Full article

Traditional settlements are vital carriers of Chinese agricultural civilization yet face mounting challenges in protection and inheritance amid rapid urbanization. Taking ancient Huizhou as a case study, this research analyzes the spatial distribution patterns of cross-provincial traditional settlements and constructs a multi-level heritage corridor network through circuit theory modeling and space syntax analysis. The study reveals a “small aggregation, large dispersion” spatial structure shaped by natural geography and socio-cultural dynamics. Simulation of multi-path cultural flows and network analysis show that high betweenness corridors concentrate along the northeast–southwest axis, promoting efficient cultural circulation, while low betweenness areas highlight gaps in direct connectivity. Closeness analysis identifies She County as the cultural core with a single-center radial structure, though internal fragmentation persists. Based on these findings, the study proposes a “three-core-driven, two-axis linkage, multi-source synergy” protection strategy to strengthens the spatial integrity and resilience of the heritage network. This research not only provides a systematic framework for the holistic conservation of Huizhou settlement heritage but also offers methodological references for the protection of traditional settlements in broader regions. Full article

The cleaning circuit of the collective Cu-Mo flotation plant at Collahuasi (north of Chile) consisted of two parallel flotation rows, each one of three first cleaner cells in series with six cleaner–scavenger cells. The second cleaner consisted of 10 parallel columns (6 rectangular and 4 circular), whose tailings were directly recycled to the first cleaner. Recently, a project was developed to upgrade the cleaning circuit by decreasing the large Mo circulating load and improving the cleaning circuit performance. For this purpose, a testing strategy was set up at a pilot scale to evaluate the use of intensified flotation (Jameson cells), mainly for collecting the fine Mo particles accumulated in the circulating load, which contributes to the Mo losses from the scavenger stage into the final tailings. The preliminary results regarding kinetics at the pilot scale showed good potential to improve the metallurgical performance of Mo and Cu, and a sensitivity study was carried out to evaluate the application of this technology in the industrial cleaning circuit. Then, two parallel Jameson cells were selected to re-treat the whole column tailings stream. This operation allowed for the generation of a direct final Cu-Mo concentrate (that joins the columns concentrate) while recycling their tailings to the first cleaner. After commissioning, three sampling campaigns were performed on the whole flotation plant, particularly on the overall cleaning circuit, to evaluate the impact of the new flotation cells. Results showed that the Jameson cells effectively decreased the minerals circulating loads in the cleaning stage, mainly for Mo (in 49%). The Jameson cells directly contribute 48% of Mo and 25% Cu of the minerals in the final concentrate and allow for increasing the Mo final grade (0.45% Mo vs. 0.29% from columns). These results were in good agreement with predictions from the pilot testing. Full article

The forced-air self-aspirating flotation machine is the core equipment for achieving a horizontal configuration in a large-scale flotation circuit. During scale-up, power consumption increases significantly due to the requirement for a greater pulp suction volume, while flotation dynamics deteriorate. Therefore, it is difficult to meet the horizontal configuration requirement for a large-scale flotation process. In this study, the key factors influencing pulp suction capacity were analyzed, revealing that as impeller submergence depth increases, pulp suction capacity decreases sharply, while power consumption rises, which was determined to be the main limitation in scaling up a forced-air self-aspirating flotation machine. To address these challenges, a new design concept for large-scale forced-air self-aspirating flotation machines was developed, featuring an impeller–stator system positioned in the middle of a trough. This design eliminated the issue of the impeller moving farther from the overflow weir and prevented increasing pulp suction resistance during scale-up. Additionally, an independent design of the upper blades was introduced based on pulp suction demand, and the design method and scale-up equations for the new impeller were established. An industrial experiment system based on a 50 m³ forced-air self-aspirating flotation machine was established to verify the developed design schemes. The new impeller with a middle placement design achieved the best separation performance, exhibited low unit pulp suction power consumption, and demonstrated the most favorable overall performance. Using CFD simulations, the flow pattern and dynamic performance were calculated, including the pulp suction volume, circulation volume, and gas–liquid dispersion for large-scale forced-air self-aspirating flotation machines. The first and largest 160 m³ large-scale forced-air self-aspirating flotation cell was successfully developed and applied in a copper–sulfur mine, where the function of self-absorbing pulp was achieved and power consumption was effectively controlled. Finally, the feasibility and accuracy of the new large-scale forced-air self-aspirating flotation machine design and scale-up method were verified. In this paper, a large forced-air self-aspirating flotation machine is designed and developed which is capable of supporting horizontally configured large-scale flotation processes. This innovative approach significantly simplifies the processing layout and reduces both the equipment configuration complexity and energy consumption, offering a more efficient and cost-effective solution for large-scale mineral processing operations. Full article

Biopsy remains the gold standard for diagnosing lung cancer, with high-quality tissue samples being critical for accurate results. To improve puncture accuracy, reduce reliance on CT imaging, and minimize procedural complications, it is essential to address the challenges of tracking the biopsy needle’s trajectory and providing real-time positional guidance to physicians. In this study, we propose a tracking model based on a rectangular toroidal current distribution to determine the biopsy needle’s relative position within the electromagnetic tracking system. A printed circuit board (PCB) is used as the platform for generating the rectangular circulating magnetic field. An alternating electromagnetic field (~70 kHz) is modeled based on the Biot–Savart law. Induced voltages from multiple transmitting coils are processed using Fourier transform algorithms to separate frequencies, enabling the independent extraction of each coil’s signal. A least squares method is employed to solve the five-degree-of-freedom electromagnetic positioning equations for the receiving coils. The objective is to establish a precise and computationally efficient electromagnetic localization model for the biopsy needle. An experimental setup simulating lung biopsy procedures is implemented, utilizing the proposed rectangular toroidal current configuration. Results demonstrate an average localization error of less than 1.76 mm, validating the effectiveness of the system in addressing the challenges of real-time biopsy needle tracking. Full article

Veno-venous extracorporeal membrane oxygenation (vvECMO) is a life-saving intervention for severe respiratory failure unresponsive to conventional therapies. However, managing refractory hypoxemia in morbidly obese patients poses significant challenges due to the unique physiological characteristics of this population, including hyperdynamic circulation, elevated cardiac output, and increased oxygen consumption. These factors can limit the effectiveness of vvECMO by diluting arterial oxygen content and complicating oxygen delivery. Refractory hypoxemia in obese patients supported by vvECMO often stems from an imbalance between ECMO blood flow and cardiac output. Hyperdynamic circulation exacerbates the recirculation of oxygenated blood and impairs the efficiency of oxygen transfer. To address these challenges, a stepwise, individualized approach is essential. Strategies to reduce oxygen consumption include deep sedation, neuromuscular blockade, and temperature control. Cardiac output modulation can be achieved through beta-blockers and cautious therapeutic hypothermia. Optimizing oxygen delivery involves improving residual lung function; high positive end-expiratory pressure ventilation guided by esophageal pressure monitoring; prone positioning; and adjustments to the ECMO circuit, such as using dual oxygenators, larger membranes, or additional drainage cannulas. This review highlights the interplay of physiological adaptations and technical innovations required to overcome the challenges of managing refractory hypoxemia in obese patients during vvECMO. By addressing the complexities of high cardiac output and obesity, clinicians can enhance the effectiveness of vvECMO and improve outcomes for this high-risk population. Full article