Search Results (188)

Tourism development potential and observed development performance do not necessarily evolve synchronously, particularly in old industrial and restructuring regions where attraction supply, market linkage, and visitor experience may be spatially uneven. This study develops a multi-source diagnostic framework for identifying tourism potential–performance mismatch across the 14 prefecture-level cities of Liaoning Province, China. Drawing on Ctrip review texts, rating scores, timestamps, platform-displayed reviewer-origin labels, A-level scenic-spot point data, and annual official city-level tourism statistics, the study constructs three dimension-specific sub-indices—the Scenic Experience Index (ESI), the Market Linkage Index (MLI), and the Attraction Foundation Index (AFI)—and synthesizes them into a Comprehensive Potential Index (CPI). The CPI is then compared with an Observed Performance Index (OPI) constructed from domestic tourist arrivals and domestic tourism revenue for 2016–2022. The results show that attraction foundation contributes most strongly to composite tourism potential, while market linkage and scenic experience condition how this structural basis is associated with observed outcomes. The CPI–OPI comparison identifies three relationship types: matched, potential-leading, and performance-leading cities. Dalian and Shenyang are high-level matched cities, Benxi and Jinzhou are high-potential but under-converted cities, and Anshan and Dandong are performance-leading cities. These findings demonstrate that favorable structural tourism conditions are not automatically transformed into realized market performance. The study contributes a multidimensional, gap-analysis-based diagnostic architecture that can support tourism-related spatial planning and territorial governance in transitional regions. Full article

The increasing penetration of inverter-based renewable energy resources, especially photovoltaic (PV) systems, has decreased the available system inertia and introduced challenges in maintaining stable grid-forming operation. This paper presents a grid-forming photovoltaic multilevel inverter (MLI) with a modified delta-connected cascaded H-bridge (CHB) multilevel configuration. The proposed system decreases the number of semiconductor switches and provides inherent voltage balancing, while also achieving high power quality, rendering it suitable for grid-forming applications. Each H-bridge cell is connected to an isolated Cúk converter to enable maximum power point tracking (MPPT) of distributed PV modules, allowing for flexible and modular DC-side integration. The proposed MLI operates as a virtual synchronous generator. A control scheme is proposed to attain grid-forming capability, hence providing stable voltage and frequency support. Moreover, a DC-link voltage regulation strategy is also developed to maintain the DC-link voltage at the reference voltage. A detailed mathematical model is developed to characterize the associated dynamics of the proposed MLI and the control system with a grid interface. The model is built in the SIMULINK environment, and the simulation results are presented under variations in solar radiation and grid voltage disturbances to exhibit the functionality of the proposed system and the effectiveness of the control scheme in providing a well-damped frequency response and stable generated voltage and currents. The results demonstrate stable frequency regulation with a settling time of approximately 0.3 s, and the output current exhibits low harmonic distortion, with a Total Harmonic Distortion (THD) of about 0.53%. Simulation results show stable operation and confirm that the proposed approach is a competitive solution for PV-based grid-forming applications. Full article

Chronic Obstructive Pulmonary Disease (COPD) is characterized by persistent inflammation and structural alterations in the lung triggered mainly by oxidative stress. Colonization by the opportunistic fungus Pneumocystis has been associated with worse clinical outcomes in COPD, yet its role in airway remodeling remains unclear. To this end, an elastase-induced COPD model was established, followed by colonization with Pneumocystis. Lung tissue was analyzed histologically and molecularly to assess epithelial thickness, alveolar morphometric parameters (mean linear intercept [MLI], D₀, D₁, D₂), inflammation, collagen deposition, and the expression of remodeling and oxidative stress markers. Emphysematous damage parameters MLI, D₀, D₁, and D₂ were markedly elevated in co-exposed animals, indicating enhanced alveolar enlargement. Animals with COPD and Pneumocystis colonization showed a significant increase in airway inflammation compared with control, COPD, and Pneumocystis groups. Airway epithelial thickness, mucus metaplasia, and collagen deposition exhibited a summative increase in the COPD/Pneumocystis group. Redox-responsive markers, such as superoxide dismutase (SOD) and catalase, were upregulated. Moreover, protein and mRNA levels of nuclear factor erythroid 2–related factor 2 (Nrf2) and its downstream gene heme oxygenase-1 (Hmox1) were significantly increased, with the strongest activation observed in co-exposed animals. Integrative correlation analysis showed that Pneumocystis burden positively correlated with lung damage, inflammation, and epithelial remodeling. These structural alterations were accompanied by coordinated activation of the antioxidant pathway Nrf2. Taken together, Pneumocystis colonization is associated with enhanced pulmonary remodeling and modulation of antioxidant signaling in experimental COPD, promoting structural and molecular changes that may contribute to disease progression. These findings suggest that Pneumocystis acts as an amplifying factor in COPD-associated lung damage. Full article

Solar photovoltaic (PV)-powered electric vehicles (EVs) have gained greater significance in the present-day era of transportation across the globe. This proposed work presents an analysis of a five-level reduced switched-capacitor multilevel inverter (RSC-MLI)-powered permanent magnet synchronous motor (PMSM) drive for solar PV-powered battery vehicles enabled by a rat swarm optimization (RSO) maximum power point tracking (MPPT) control mechanism. The system proposed in this paper integrates solar PV arrays and battery storage systems for efficient power transfer to EVs for propulsion. In order to achieve fast, accurate tracking of the optimal maximum power point, the RSO technique is used. A five-level RSC-MLI is used in this study, which enables boosting the voltage and lowering switching losses in the system. The performance of the PMSM is further analyzed to obtain constant parameters, such as the velocity and torque of the electric vehicle. Full article

Mitochondrial dysfunction plays a central role in the pathogenesis of bronchopulmonary dysplasia (BPD). Solute carrier family 25 member 28 (SLC25A28) is an iron transporter located in the inner mitochondrial membrane. In this study, we aimed to explore the role and underlying molecular mechanisms of SLC25A28 in BPD. Hyperoxia (85% O₂) was used to establish a neonatal murine model of BPD, and mouse lung epithelial cells (MLE-12 cells) were used in vitro. SLC25A28 expression and activity were downregulated under hyperoxic conditions, both in vivo and in vitro. SLC25A28 overexpression restored hyperoxia-induced mitochondrial oxidative phosphorylation (OXPHOS) dysfunction, and further enhanced the proportion of Ki67-positive cells by 37% (p < 0.05) and increased migration by 33% (p < 0.01) in MLE-12 cells. In contrast, SLC25A28 knockdown exacerbated these impairments in MLE-12 cells, with reduced the proportion of Ki67 positive cells by 71% (p < 0.01) and a 35% reduction in the migration rate. SLC25A28 was also knocked down in vivo, which further aggravated alveolar simplification in BPD mice. Furthermore, the mitochondrial-targeted peptide SS-31 could potentially interact with SLC25A28 and preserve its protein abundance. SS-31 administration mitigated hyperoxia-induced alveolar simplification, with the radical alveolar count (RAC) increasing by 28% (p < 0.05) and the mean linear intercept (MLI) decreasing by 20% (p < 0.001). In summary, this study revealed that SLC25A28 ameliorated hyperoxic lung injury by improving mitochondrial OXPHOS in alveolar epithelial cells, suggesting that it may serve as a potential therapeutic target for BPD. Full article

Deep learning (DL) techniques have significantly advanced wind power forecasting by enhancing accuracy. However, these DL models are vulnerable to adversarial attacks, which can lead to severely inaccurate forecasts. Existing studies in wind power forecasting have rarely addressed the stealthiness and effectiveness of adversarial attacks simultaneously, nor have they investigated defense strategies against multiple perturbation strengths or in black-box scenarios. To this end, we propose an attack algorithm for wind power forecasting, i.e., the momentum iterative fast gradient sign method (MI-FGSM). This algorithm generates adversarial samples by incorporating momentum into the iterative process and adding perturbations to the input samples along the gradient direction. To defend against such attacks under varying perturbation strengths, a defense model called multi-level iterative denoising autoencoder (MLI-DAE) is proposed. MLI-DAE is trained using adversarial samples with multiple perturbation levels to effectively restore attacked inputs to their clean forms. Experimental results under both white-box and black-box scenarios demonstrate that MI-FGSM induces significantly larger forecast errors with smaller perturbation magnitudes compared to FGSM. Furthermore, our proposed MLI-DAE effectively defends against multi-level perturbations without compromising the original forecast accuracy. Full article

Bacterial poly(A) polymerases (PAPs) play an important role in RNA metabolism but remain poorly characterized outside Gammaproteobacteria. Here, we cloned and biochemically characterized the first PAP from Alphaproteobacteria, specifically from Marinobacter lipolyticus (Mli PAP). Using homology-based screening against E. coli PAP-1, we identified Mli PAP, sharing 54.8% sequence identity with its E. coli counterpart. The enzyme was expressed in E. coli but formed insoluble inclusion bodies; the active enzyme was purified as a fusion protein with the DsbA protein and used for functional assays. Mli PAP exhibited optimal activity at 30 °C and similar thermostability to E. coli PAP-1. ATP was the preferred substrate, with K_m comparable to E. coli PAP-1 (1.61 mM and 1.70 mM, respectively), and Mg²⁺ (10 mM) was identified as the optimal cofactor. Mli PAP displayed salt-dependent activity, with the most effective polyadenylation in KCl and inhibition by NaCl and ammonium salts, contrasting with the halophilic nature of its host. This study provides the first functional insights into PAPs from Alphaproteobacteria, broadening the understanding of PAP diversity and biochemical properties, as well as the potential applications of PAPs in biotechnology. Full article

In this study, the influence of residual gas pressure within a vacuum insulation cavity on the insulation performance of a multi-layer insulation (MLI) system was investigated through thermal analysis. Based on an electrical analogy, a thermal resistance network was constructed, considering heat transfer through the insulation system by gas conduction, solid conduction, and surface radiation. Lees’ four-moment model was employed to calculate the gas conduction across a wide range of vacuum conditions, including medium-to-low vacuum situations. The analysis shows that total heat flux and effective thermal conductivity exhibited non-linear increases as the pressure approached atmospheric level. This trend was successfully validated by comparisons with experimental data from the literature, thereby confirming the rationality of the proposed analytical model. Furthermore, the contributions of individual heat-transfer modes to the total heat flux within the insulation system were scrutinized, thereby revealing their redistribution patterns. Under high-vacuum conditions, solid conduction and radiation were the primary modes of heat transfer. However, with increasing pressure, the proportion of gas conduction rose markedly, becoming the primary heat-transfer mode under medium-vacuum and low-vacuum conditions. Finally, a validated analytical technique was utilized to predict heat-transfer characteristics under cryogenic boundary conditions associated with liquid hydrogen storage. Full article

This article proposes a parallel current-summing LCC multilevel inverter (MLI) to suppress harmonic distortion of radiated EMI for wireless power transfer. Traditionally, ZVS has been an issue for staircase voltage output multilevel inverters because a shared current output became faster than some of the voltage transitions in staircase voltage output. The other common problem was capacitor voltage imbalance and resultant output voltage distortion if a sophisticated voltage balancing function is not used. The proposed LCC MLI ensures ZVS by separating each voltage transition into multiple bridge legs. Each bridge leg outputs different phases of currents for each voltage transition. The individual output currents are summed at the matching network of wireless power transfer, generating a near-sinusoid output current to suppress harmonic distortions. In this way, each leg achieves ZVS even though the summed output current at the LCC network is faster than some of the voltage transitions. To avoid the capacitor voltage imbalance issue, the proposed MLI eliminated the flying capacitor. Instead, the four parallel legs are supplied by a shared DC input link. Therefore, the four legs can output identical voltages without using a typical DC flying capacitor. The necessity of multiple input voltage sources is, therefore, also eliminated. Measurement demonstrates that the proposed method effectively reduces radiated harmonic EMI by up to 14 dB. Full article

Mutations in leucine-rich repeat kinase 2 (LRRK2) are among the most common genetic causes of Parkinson’s disease (PD), yet substantial heterogeneity exists among pathogenic variants. How mutations in distinct functional domains of LRRK2 differentially perturb cellular homeostasis remains incompletely understood. Here, we compared two pathogenic LRRK2 mutations—G2019S in the kinase domain and I1371V in the GTPase domain—across multiple cellular models, including SH-SY5Y and U87 cells, and healthy human iPSC-derived floor plate cells. We demonstrate that the I1371V mutation induces markedly more severe cellular dysfunction than G2019S. I1371V-expressing cells exhibited elevated LRRK2 autophosphorylation at S1292 and robust hyperphosphorylation of Rab8A and Rab10, indicating enhanced downstream signaling. These alterations impaired sterol trafficking, leading to selective depletion of membrane cholesterol without changes in total cellular cholesterol. Consequently, I1371V cells displayed increased membrane fluidity, disrupted microdomain organization, altered membrane topology, reduced caveolin-1 expression, and impaired dopamine transporter surface expression and dopamine uptake. Lipidomic profiling further revealed a broad disruption of lipid homeostasis, including reductions in cholesteryl esters, sterols, sphingolipids, and glycerophospholipids, whereas G2019S cells showed comparatively modest changes. Pharmacological intervention revealed mutation-specific responses, with the non-selective LRRK2 modulator GW5074 outperforming the kinase-selective inhibitor MLi-2 in restoring Rab8A phosphorylation, membrane integrity, and dopaminergic function. Collectively, these findings identify membrane lipid dysregulation as a central cell biological mechanism in LRRK2-associated PD and underscore the importance of variant-specific therapeutic strategies. Full article

The rise of carbon emissions from fossil fuel-based power generation has intensified the need for efficient and low-carbon energy systems. The global CO₂ concentration has risen from 285 ppm in the pre-industrial era to nearly 420 ppm today, and this contributes to a 1°C increase in average temperature. Therefore, in this article, a hybrid photovoltaic–thermoelectric generator (PV–TEG) system integrated with a reduced-switch multilevel inverter (MLI) is proposed. This enhances renewable energy utilization and power quality. The proposed PV–TEG model recovers waste heat from PV modules, which yields an overall efficiency improvement of approximately 2–8% compared to standalone PV systems. Further, the proposed MLI operates in symmetric (seven-level) and asymmetric (11-level) modes using eight switches. The system develops high-quality stepped output voltages with a minimum component count. Simulation work is performed, and the results show a peak output voltage of ±220 V with Total Harmonic Distortion (THD) of 7.2% under R-load and reduced THD below 5% under RL and variable load conditions. The integrated system demonstrates improved efficiency, reliability, and suitability for sustainable power generation and rural electrification. Full article

Cryogenic storage systems require precise management of boil-off gas (BOG) to prevent pressure buildup caused by external heat ingress. This study investigates sloshing-induced heat transfer and BOG generation in a double-shell vacuum-insulated cryogenic storage tank subjected to dynamic excitation. Experiments were conducted under dynamic operating conditions, during which BOG generation and boil-off rate (BOR) were measured over a range of vibration frequencies, acceleration levels, and fill ratios. The results reveal a strong frequency-dependent sloshing behavior that significantly influences BOG generation. Under dynamic conditions, the BOR exhibited a non-linear dependence on filling ratio, with a maximum response occurring at 50% filling, reflecting an optimal balance between sloshing-enhanced heat transfer and geometric confinement. Based on the experimental observations, an integrated numerical heat transfer model incorporating multilayer insulation (MLI) performance and vacuum level effects was developed and validated against experimental data. The validated numerical model successfully predicts pressure evolution and BOG generation under operational sloshing conditions, providing valuable insights for optimizing cryogenic tank design and minimizing boil-off losses. Full article

This paper proposes a dynamic voltage restorer (DVR) based on a new three-phase multilevel inverter (MLI). An integral component of DVRs is the power electronic converter. At medium-to-high voltage levels, MLIs are the ideal converters for DVR applications because lower voltage-rated switches are used to generate high voltages, thus minimizing power losses. The proposed three-phase MLI generates 15 levels of load voltage per phase, using a reduced component count: eight lower-rated semiconductor power switches, four primary DC voltage sources, two auxiliary DC sources, and eight driver circuits per phase. Additionally, each phase features a low-frequency transformer with voltage-boosting and galvanic isolation capabilities. The switching sequence of the proposed MLI is simpler to execute using fundamental frequency control; this methodology provides reduced switching stress and reduced switching losses as merits. Structurally, the proposed MLI is less complex and thus scalable. The proposed DVR, based on three-phase MLI, efficiently offsets power quality problems such as voltage swell, voltage sags, and harmonics for balanced and unbalanced loads. The operational performance of the proposed DVR-MLI is verified by a simulation, using PSCAD software and an experimental prototype. Full article

Measuring the fatigue crack growth rate via the crack growth experiment (a-N curve) is labor-intensive and time-consuming. A machine learning interpolation–extrapolation strategy (MLIES) aimed at enhancing the prediction accuracy of small-data models has been proposed to accelerate fatigue testing. Two specific approaches are designed by transforming a-N curve data from N to ΔN and from a to Δa (S1)/Δa/ΔN (S2) to enrich the data volume and leverage the incremental information. Thus, a simple and fast-responding single-layer neural network model can be trained based on the early-stage data points from fatigue testing and accurately predict the remaining part of an a-N curve, thereby enhancing the experimental efficiency. Through exponential data expansion and data augmentation, the trained neural network model is able to learn the underlying rules governing crack growth directly from the experimental data, requiring no explicit analytical crack growth laws. The proposed MLIES was validated on fatigue tests for aluminum alloy and titanium alloy samples under different experimental parameters. Results demonstrate its effectiveness in reducing testing time/cost by 15–32% while achieving over 30% higher prediction accuracy for the a-N curve compared to a traditional machine learning modeling approach. Our research offers a data-driven recipe for accurate crack growth prediction and accelerated fatigue testing. Full article

With the increasing integration of renewable energy sources into the grid, power quality at the point of common coupling (PCC)—particularly harmonic distortion introduced by power electronic converters—has become a critical concern. This paper presents a rigorous design and evaluation of a three-phase, fifteen-level cascaded H-bridge multilevel inverter (CHB MLI) with an LCL filter, selected for its superior harmonic attenuation, compact size, and cost-effectiveness compared to conventional passive filters. The proposed system employs Phase-Shifted Pulse Width Modulation (PS PWM) for balanced operation and low output distortion. A systematic, reproducible methodology is used to design the LCL filter, which is then tested across a wide range of switching frequencies (1–5 kHz) and grid impedance ratios (X/R = 2–9) in MATLAB/Simulink R2025a. Comprehensive simulations confirm that the filter effectively reduces both voltage and current total harmonic distortion (THD) to levels well below the 5% limit specified by IEEE 519, with optimal performance (0.53% current THD, 0.69% voltage THD) achieved at 3 kHz and X/R ≈ 5.6. The filter demonstrates robust performance regardless of grid conditions, making it a practical and scalable solution for modern renewable energy integration. These results, further supported by parametric validation and clear design guidelines, provide actionable insights for academic research and industrial deployment. Full article