Uneven Distribution Research Articles

Reducing flow heterogeneity in drip irrigation networks using genetic algorithms

AbstractIrrigation based on non‐compensated drip emitters is extremely common in agriculture, especially due to its simplicity, robustness and competitive cost. Nevertheless, because of friction losses in the pipe, together with irregular terrain, these systems often suffer from uneven water distribution in the drip emitters, which not only results in inefficient use of water resources but also might lead to inadequate irrigation in certain parts of the field. This work proposes to design the topology of the irrigation network to compensate for these discharge differences. To this end, a graph‐based mathematical model is developed to determine the discharge flows at different emitters for any network topology. This model is employed to formulate an integer nonlinear optimization problem, for which a messy genetic algorithm is proposed. The methodology is validated on an example problem, which is based on a rectangular agricultural crop of 49 fruit trees. The results revealed a 70% reduction in the coefficient of variation of the irrigation discharge rates, which was employed as a metric of irrigation uniformity. This caused a 75% reduction in the water excess. The results demonstrate that the uniformity can be improved simply by choosing a proper connectivity layout to build the pipe network.

Optimization of the Thermokinetic Method for the Control of Weld Decay in AISI 304L and AISI 316L Stainless Steel Weldment

This study investigates the control of weld decay in AISI 304L/316L alloy weldments for liquefied natural gas (LNG) and cryogenic environments using the Tungsten Inert Gas (TIG) welding technique. Weldment samples were thermokinetically treated at 1050, 1100, and 1150°C and cooled in five mediums: Water, Salt, Natural Air, Salt with annealing, and Water with annealing, to retain carbon and chromium in solid solution at approximately 30°C. Furthermore, evaluation methods based on metallography i.e. optical microscopy (OM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX), Wear Test (i.e. wear rate and wear track) and electrochemical corrosion potential measurements were adopted. An experimental design table was developed using the design expert software 13.0. This helped develop a predictive mathematical model for ascertaining the optimum operating service conditions of the material. From the results, the optical microscopy analysis revealed that the control sample exhibited a more irregular pattern than others. Results showed that the control sample had a more irregular structure, while air-cooled samples exhibited smoother surfaces, indicating better bonding. SEM revealed a coarse surface with uneven particle distribution post-heat application. The predominant elements were Iron (Fe), Chromium (Cr), and Nickel (Ni). Corrosion potential varied between -0.5 to 0.15 V, demonstrating wave-like behaviour over time. Wear analysis indicated that lower coefficients of friction correlate with better wear resistance. Finally, response surface methodology (RSM) revealed that increasing temperature proportionally increased yield and corrosion rates. While the identified optimal values for Temperature are (1112.68°C), Material (316L), and Quenching Medium (SQ+SA), resulting in specific values such as Wear Rate (5.76896E-06), Coefficient of friction (0.224254), Corrosion Rate (0.395566), and Weight of Heat-Treated Sample (14.7797). The study enhances understanding of the mechanisms affecting welding and contributes to optimizing welding procedures for improved mechanical properties and corrosion resistance.

Flexibilizing Mechanisms of Spinel-, Hercynite-, Galaxite-, and Chromite-Containing Basic Refractories for Cement Rotary Kilns

Background: Refractory linings of cement rotary kilns are subjected to severe thermomechanical stresses of cranking, ovality, tyre hooping/migration, and uneven thermal distribution. An insistent demand is to discover the significance of spinel, hercynite, galaxite, and chromite in magnesia refractories, as well as their flexibilizing mechanisms. Objectives: The objectives are to compare the fracture behavior of magnesia–spinel, – hercynite, -galaxite, and -chromite refractories and to unveil the flexibilizing mechanisms of different spinels. Methods: The wedge-splitting test is carried out to produce various fracture parameters. Their flexibilizing mechanisms are unveiled by performing microstructural observations and analyses. Results: Various fracture parameters are obtained, including specific fracture energy, brittleness number, characteristic crack length, and thermal-shock resistance parameter. Generally, magnesia–hercynite bricks and magnesia–galaxite bricks have demonstrated the obvious advantages of fracture resistance, which are more flexible than magnesia–spinel bricks and magnesia–chromite bricks. Conclusion: The flexibility of magnesia–spinel bricks is attributed to microcracks generated from the thermal mismatch between spinel grains and surrounding periclase, which is recognized as the thermal-expansion mismatch mechanism. In magnesia–hercynite and magnesia-galaxite refractories, the active-ion-diffusion mechanism is predominant beyond similar microcracks, to drive the flexibility by the continuous diffusion of Fe2+, Mn2+, and Mg2+ during high-temperature processes. In magnesia–chromite bricks, the pore rims contribute to the flexibility as a silicate-migration mechanism, after silicate envelopes first arise around chromite grains and then vanish into the surrounding magnesia by the suction of capillary force during the burning process.

Analyzing Operational Dynamics: Centralized Load Distribution and Suspended Wagons in Self‐Propelled Trains

ABSTRACTThis paper primarily focuses on the distribution of axial loads in railway networks. The analysis assesses the advantages and disadvantages of articulated trains. In addition, the perspectives and proposed solutions of academicians are analyzed. Simpack accurately models all aspects of this articulated train model. Subsequently, the program emulates the control system of the train. This study demonstrates a control system that utilizes a hydraulic actuator. The proposed model and control system actuator's dynamic response are evaluated according to EN14363 and UIC518 standards to validate the functionality of the component. The stability of a railway train, particularly when making turns, relies on the proper allocation of weight on the wheels and axles. This research investigates the hazards associated with the uneven distribution of loads in train wagons, particularly when navigating curving tracks. A train designed for intercity travel was constructed utilizing a specific control system. The discrepancy in axle load is mitigated by implementing a straightforward control method. The train's carriage, which is suspended without bogies, resulted in fluctuating axle load. A disparity in axle load was established by an actuator positioned between the wagons. The control mechanism minimized load disparity and regulated axle load.

Multi-Agent Deep Reinforcement Learning for Blockchain-Based Energy Trading in Decentralized Electric Vehicle Charger-Sharing Networks

With The integration of renewable energy sources into smart grids and electric vehicle (EV) charger-sharing networks is essential for achieving the goal of environmental sustainability. However, the uneven distribution of distributed energy trading among EVs, fixed charging stations (FCSs), and mobile charging stations (MCSs) introduces challenges such as inadequate supply at FCSs and prolonged latencies at MCSs. In this paper, we propose a multi-agent deep reinforcement learning (MADRL)-based auction algorithm for energy trading that effectively balances charger supply with energy demand in distributed EV charging markets, while also reducing total charging latency. Specifically, this involves a MADRL-based hierarchical auction that dynamically adapts to real-time conditions, optimizing the balance of supply and demand. During energy trading, each EV, acting as a learning agent, can refine its bidding strategy to participate in various local energy trading markets, thus enhancing both individual utility and global social welfare. Furthermore, we design a cross-chain scheme to securely record and verify transaction results of energy trading in decentralized EV charger-sharing networks to ensure integrity and transparency. Finally, experimental results show that the proposed algorithm significantly outperforms both the second-price and double auctions in increasing global social welfare and reducing total charging latency.

Genome-wide identification and expression analysis of two-component system genes in switchgrass (Panicum virgatum L.)

The two-component system (TCS) consists of histidine kinase (HK), histidine phosphate transfer protein (HP), and response regulatory factor (RR). It is one of the most crucial components of signal transduction in plants, playing a significant role in regulating plant growth, development, and responses to various abiotic stresses. Although TCS genes have been extensively identified in a variety of plants, the genome-wide recognition and examination of TCS in switchgrass remain unreported. Accordingly, this study identified a total of 87 TCS members in the genome of switchgrass, comprising 20 HK(L)s, 10 HPs, and 57 RRs. Detailed analyses were also conducted on their gene structures, conserved domains, and phylogenetic relationships. Moreover, this study analysed the gene expression profiles across diverse organs and investigated their response patterns to adverse environmental stresses. Results revealed that 87 TCS genes were distributed across 18 chromosomes, with uneven distribution. Expansion of these genes in switchgrass was achieved through both fragment and tandem duplication. PvTCS members are relatively conservative in the evolutionary process, but the gene structure varies significantly. Various cis-acting elements, varying in types and amounts, are present in the promoter region of PvTCSs, all related to plant growth, development, and abiotic stress, due to the TCS gene structure. Protein-protein interaction and microRNA prediction suggest complex interactions and transcriptional regulation among TCS members. Additionally, most TCS members are expressed in roots and stems, with some genes showing organ-specific expression at different stages of leaf and inflorescence development. Under conditions of abiotic stress such as drought, low temperature, high temperature, and salt stress, as well as exogenous abscisic acid (ABA), the expression of most TCS genes is either stimulated or inhibited. Our systematic analysis could offer insight into the characterization of the TCS genes, and further the growth of functional studies in switchgrass.

BRIDGING THE DIGITAL GAP: ANALYSING THE IMPACT OF ICT DIFFUSION ON INCOME INEQUALITY IN INDONESIA

The development of information and communication technology (ICT) has significantly transformed the socio-economic structure of society, particularly in terms of income distribution. This study aims to analyse the impact of ICT development on income inequality across 34 provinces in Indonesia from 2012 to 2020, employing econometric methods based on panel data through a fixed effects model. Empirical findings reveal that ICT readiness and ICT skills tend to exacerbate income inequality, while ICT use and its quadratic form contribute to reducing it. These results suggest that although ICT infrastructure and skills are crucial, their uneven distribution and utilisation can widen income disparities. Consequently, this study highlights the importance of ensuring equitable access to ICT across Indonesia to mitigate economic inequality. The study's recommendations stress the pivotal role of the government in expanding ICT infrastructure, fostering a research and innovation climate conducive to digital transformation, and formulating policies that enhance ICT skills nationwide. These measures would improve digital literacy, upgrade workforce capabilities, and promote inclusive digital economic growth. Ultimately, comprehensive and equitable ICT development can play a critical role in reducing income inequality across Indonesia.

Coordinatively Unsaturated Co Single-Atom Catalysts Enhance the Performance of Lithium-Sulfur Batteries by Triggering Strong d-p Orbital Hybridization.

The catalytic activities displayed by single-atom catalysts (SACs) depend on the coordination structure. SACs supported on carbon materials often adopt saturated coordination structures with uneven distributions because they require high-temperature conditions during synthesis. Herein, bisnitrogen-chelated Co SACs that are coordinatively unsaturated are prepared by integrating a Co complex into a conjugated microporous polymer (CMP-CoN2). Compared with saturated analogues, i.e., tetranitrogen-chelated Co SACs (denoted as CMP-CoN4), CMP-CoN2 exhibits higher electrocatalytic activity in polysulfide conversions due to an enhanced hybridization between the 3d orbitals of the Co atoms and the 3p orbitals of the S atoms in the polysulfide. As a result, sulfur cathodes prepared with CoN2 deliver outstanding performance metrics, including a high specific capacity (1393 mA h g-1 at 0.1 C), a superior rate capacity (673.2 mA h g-1 at 6 C), and a low capacity decay rate (of only 0.045% per cycle at 2 C over 1000 cycles). They also outperform sulfur cathodes that contain CMP-CoN4 or CMPs that are devoid of Co SACs. This work reveals how the catalytic activity displayed by SACs is affected by their coordination structures, and the rules that underpin the structure-activity relationship may be extended to designing electrocatalysts for use in other applications.

PDeT: A Progressive Deformable Transformer for Photovoltaic Panel Defect Segmentation.

Defects in photovoltaic (PV) panels can significantly reduce the power generation efficiency of the system and may cause localized overheating due to uneven current distribution. Therefore, adopting precise pixel-level defect detection, i.e., defect segmentation, technology is essential to ensuring stable operation. However, for effective defect segmentation, the feature extractor must adaptively determine the appropriate scale or receptive field for accurate defect localization, while the decoder must seamlessly fuse coarse-level semantics with fine-grained features to enhance high-level representations. In this paper, we propose a Progressive Deformable Transformer (PDeT) for defect segmentation in PV cells. This approach effectively learns spatial sampling offsets and refines features progressively through coarse-level semantic attention. Specifically, the network adaptively captures spatial offset positions and computes self-attention, expanding the model's receptive field and enabling feature extraction across objects of various shapes. Furthermore, we introduce a semantic aggregation module to refine semantic information, converting the fused feature map into a scale space and balancing contextual information. Extensive experiments demonstrate the effectiveness of our method, achieving an mIoU of 88.41% on our solar cell dataset, outperforming other methods. Additionally, to validate the PDeT's applicability across different domains, we trained and tested it on the MVTec-AD dataset. The experimental results demonstrate that the PDeT exhibits excellent recognition performance in various other scenarios as well.

The analysis of the overall failure of practical Zn−Ni battery

Zn−Ni batteries are viewed as promising power sources for electric tools and electric vehicles (EVs) due to their benefits of high safety, high working voltage and attractive rate performance. However, the practical applications of the Zn−Ni batteries are hampered by poor cycling performance, posing significant challenges for their widespread utilization. To effectively address this pressing concern, a profound investigation of the intrinsic failure mechanisms underlying Zn−Ni batteries holds paramount importance. This paper carries out a thorough analysis of battery behavior to simulate industrial application scenarios using two different assembly methods of Zn−Ni batteries. One type is a battery composed of one Ni(OH)2 cathode and one Zn anode (abbreviated as OO). The other type is the battery assembled with one Ni(OH)2 cathode and two Zn anodes (abbreviated as OT). Ultimately, it is revealed that the principal factors of Zn anode failure in OO battery are the growth of zinc dendrites, passivation and uneven current distribution. In contrast, for OT battery, the cathode emerges as the failed electrode. Specifically, the rupture of spheres on the positive electrode surface and the detached powder from the substrate result in the decline in capacity and finally the failure of the battery. Two classical battery assembly methodologies were employed to investigate in-depth the failure mechanisms of Zn−Ni batteries, ultimately revealing that the reasons for battery failure mechanism differed, thus providing valuable and practical guidance for future research aimed at enhancing battery lifespan.

Trends in Regional Disparities of Cardiovascular Surgery and Mortality in South Korea

Abstract Objectives Regional disparities in cardiovascular care in South Korea have led to uneven patient outcomes. Although procedure access and needs are increasing, few studies have linked regional service availability to mortality rates. This study analyzed variation in utilization of major cardiovascular procedures by region and association with short-term mortality to provide better evidence on links between healthcare resources distribution and patient survival. Methods A cross-sectional study was conducted using nationwide claims data on patients who underwent coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), stent insertion, or aortic aneurysm resection in 2022. Regional variation was assessed by a Relevance Index (RI). The associations between regional RI and 30-day mortality were analyzed. Results The RI was lowest for aortic aneurysm resection (mean, 26.2; standard deviation, 26.1), indicating the most uneven regional distribution among the surgical procedures. Patients undergoing this procedure in regions with higher RIs showed significantly lower 30-day mortality (adjusted odds ratio [aOR], 0.73; 95% confidence interval, 0.55 to 0.96; p = 0.026) versus those with lower RIs. This suggests that cardiovascular surgery regional availability, as measured by RI, has an impact on mortality rates for certain complex surgical procedures. The RI was not associated with significant mortality differences for more widely available procedures like CABG (aOR, 0.96), PCI (aOR, 1.00), or stent insertion (aOR, 0.91). Conclusions Significant regional variation and underutilization of cardiovascular surgery were found, with reduced access linked to worse mortality for complex surgeries. Addressing disparities through cooperation among hospitals and policy efforts is warranted to improve outcomes. Key messages • This study analyzed regional variations in major cardiovascular procedures using the Relevance Index and investigated their impact on mortality rates within 30 days of admission. • Addressing regional disparities requires improved healthcare infrastructure and comprehensive networks of specialists to ensure timely and high-quality cardiovascular care across South Korea.

Quasi-static modeling of a full-channel effective magnetorheological damper with shunt and bending magnetic circuit

Magnetorheological dampers (MRD) are widely used in vibration control due to their rapid response and adjustable damping forces. However, conventional MRD designs with closed rectangular magnetic circuits suffer from limited effective working lengths and inadequate damping force for vehicle suspensions. To address this, a novel full-channel effective MRD with shunt and bending magnetic circuit (FEMRD_SB) is proposed. This design increases the effective working length of the damping channel by incorporating a bending motion in the magnetic circuit. Magnetic circuit shunting is integrated to mitigate magnetic leakage during bending, improving energy utilization efficiency. To better meet the practical needs of vehicle suspension, a quasi-static mathematical model aiming to explain the mechanical properties of the damper is investigated. Traditional models often overlook the uneven distribution of magnetic fields, which leads to poor modeling accuracy. To improve the precision of the quasi-static model, a multiphysical field coupling quasi-static modeling method is proposed. This method, utilizing the Takagi–Sugeno fuzzy neural network establishes the relationship between magnetic field and displacement, facilitating the integration of magnetic, flow, and solid fields for more precise modeling outcomes. Simulations and experiments validate the effectiveness of the FEMRD_SB and the quasi-static model. The real-vehicle experiments demonstrate that the FEMRD_SB effectively suppresses the sprung mass acceleration of a vehicle, improving the vehicle’s ride comfort.

Implications for Paleontological Heritage Conservation: The Spatial Distribution and Potential Factors Controlling the Location of Fossil Sites of Shandong Province in China

Shandong Province in China is rich in paleontological fossils and has a long history of fossil research. However, research on the distribution characteristics and potential factors of discovered fossil sites in Shandong Province is limited and insufficient, making it difficult to comprehensively plan for the protection and utilization of fossil sites in Shandong Province. The study constructs a basic geographical information system (GIS) database with 133 discovered fossil sites and geological and socio-economic data of Shandong Province and studies fossil sites’ spatial distribution characteristics and the spatial relationship with potential factors at a regional scale. The results are as follows: (1) The fossil sites in Shandong Province are concentrated in the mountainous area of central Shandong and the hilly area of the Shandong Peninsula, with significant uneven distribution characteristics, including two agglomeration areas and seven sub-agglomeration areas. (2) Natural geographical conditions, such as topography, paleogeography, and stratigraphy, play a positive role in the distribution of fossil sites, and there are apparent concentrations in the following areas: at an altitude greater than 100 m; the Lower Paleozoic and Cretaceous sedimentary rocks; and the active areas of paleo-tectonics. (3) A certain degree of negative correlation exists between socio-economic conditions, such as roads and population density, and the number of fossil sites, and a positive correlation exists between disposable personal income and those fossil sites. The operational procedure presented here is a simple, objective, applicable method that can enhance our understanding of the spatial distribution patterns and influencing factors of the discovered fossil sites of Shandong Province and support more effective and appropriate planning for paleontological heritage conservation.

Socio-economic gradients in urban green space access and respiratory health

Abstract Background This study investigates social disparities as one of the drivers influencing the access to green spaces and exposure to natural environments, potentially exacerbating disparities in respiratory health in children. Methods Longitudinal ELSPAC birth cohort study data included 4384 complete case participants born in cities of Brno and Znojmo, examined throughout the years 1990-2010. Estimates on socio-economic status (SES) scores of children’s parents and their education were used as socio-economical predictors. Tree cover density (TCD) calculated as mean canopy closure percentage in the individual walking distance neighbourhoods and the ownership and accessibility of a garden were used as indicators of green space accessibility. Multiple logistic regression models were employed to estimate odds ratios for predictors of respiratory health outcomes, controlling for several confounders. Results Parents’ SES was found to be positively associated with neighbourhood TCD, and this effect was even more pronounced for garden owners. Higher tree cover was then significantly negatively associated with development of acute bronchitis (OR 0.88, CI 95 % 0.84-0.94 for 1 SD of tree cover), while not having a garden (OR 1.81, CI 95 % 1.42-2.33) and living in area with lower tree cover (OR continuously decreasing from 1.88 to 1.68 for lowest and highest quartile respectively) was significantly associated with progression of acute bronchitis into chronic bronchitis in a fully adjusted model. Vice versa, higher tree cover was statistically significantly positively associated with development of allergic rhinitis (OR 1.09, CI 95 % 1.03-1.15), suggesting viability of the novel method of estimation of individual neighbourhood greenness. Conclusions The results suggest protective effect of access to urban green spaces against adverse respiratory outcomes in children. The socially uneven distribution of access emphasizes the importance of urban policies in promoting urban health. #NGEU Key messages • There is a significant protective effect of access to green spaces against respiratory diseases and their progression. • There’s an unequal, but varied distribution of access to green spaces, and social gradient in health, highlighting the importance of urban green space distributive politics.

AN INTEGRATED APPROACH TO IDENTIFY SUITABLE AREAS FOR THE LOCATION OF PUBLIC FACILITIES USING MULTI-CRITERIA ANALYSIS BASED ON GIS AND AHP IN THE CITY OF EL KHROUB, ALGERIA

Random and spontaneous urban growth is the result of massive natural population growth, as it is in all developing countries. As for our study air, it also results from the unloading of the mother city of Constantine to the satellite city of El-Khroub, which gave urbanization the power to take over its vast environment, An uneven distribution of public facilities in the city’s major districts, as well as traffic jams. This work attempted to determine the suitability of urban land for the location of public facilities in the city. It should be noted that land suitability assessment is a major factor in urban planning and management. Our land adequacy assessment is subject to the AHP model, calculating the weighting of various criteria including physical, socio-economic, environmental and urban. The final adequacy analysis revealed the proportion of land most suitable, estimated at 3.52% of the total area, covering mainly fallow land. The results of this study provide a detailed mapping of urban development potential, integrating both existing data and future projections.

MNCATM: A Multi-Layer Non-Uniform Coding-Based Adaptive Transmission Method for 360° Video

With the rapid development of multimedia services and smart devices, 360-degree video has enhanced the user viewing experience, ushering in a new era of immersive human–computer interaction. These technologies are increasingly integrating everyday life, including gaming, education, and healthcare. However, the uneven spatiotemporal distribution of wireless resources presents significant challenges for the transmission of ultra-high-definition 360-degree video streaming. To address this issue, this paper proposes a multi-layer non-uniform coding-based adaptive transmission method for 360° video (MNCATM). This method optimizes video caching and transmission by dividing non-uniform tiles and leveraging users’ dynamic field of view (FoV) information and the multi-bitrate characteristics of video content. First, the video transmission process is formalized and modeled, and an adaptive transmission optimization framework for a non-uniform video is proposed. Based on this, the optimization problem required by the paper is summarized, and an algorithm is proposed to solve the problem. Simulation experiments demonstrate that the proposed method, MNCATM, outperforms existing transmission schemes in terms of bandwidth utilization and user quality of experience (QoE). MNCATM can effectively utilize network bandwidth, reduce latency, improve transmission efficiency, and maximize user experience quality.

Does gut microbiota dysbiosis impact the metabolic alterations of hydrogen sulfide and lanthionine in patients with chronic kidney disease?

BackgroundChronic Kidney Disease (CKD) is characterized by a methionine-related metabolic disorder involving reduced plasma levels of hydrogen sulfide (H2S) and increased lanthionine. The gut microbiota influences methionine metabolism, potentially impacting sulfur metabolite dysfunctions in CKD. We evaluated whether gut microbiota dysbiosis contributes to H2S and lanthionine metabolic alterations in CKD.MethodsThe gut microbiota of 88 CKD patients (non-dialysis, hemodialysis, and transplant patients) and 26 healthy controls were profiled using 16 S-amplicon sequencing. H2S and lanthionine concentrations were measured in serum and fecal samples using the methylene blue method and LC-MS/MS, respectively.ResultsThe CKD population exhibited a tenfold increase in serum lanthionine associated with kidney dysfunction. Despite lanthionine retention, hemodialysis and transplant patients had significantly lower serum H2S than healthy controls. Fecal H2S levels were not altered or related to bloodstream H2S concentrations. Conversely, fecal lanthionine was significantly increased in CKD compared to healthy controls and associated with kidney dysfunction. Microbiota composition varied among CKD groups and healthy controls, with the greatest dissimilarity observed between hemodialysis and transplant patients. Changes relative to the healthy group included uneven Ruminococcus gnavus distribution (higher in transplant patients and lower in non-dialysis CKD patients), reduced abundance of the short-chain fatty acid-producing bacteria Alistipes indistinctus and Coprococcus eutactus among transplant patients, and depleted Streptococcus salivarius in non-dialysis CKD patients. A higher abundance of Methanobrevibacter smithii, Christensenella minuta, and Negativibacillus massiliensis differentiated hemodialysis patients from controls. No correlation was found between differentially abundant species and the metabolic profile that could account for the H2S and lanthionine alterations observed.ConclusionsThe metabolic deregulation of H2S and lanthionine observed in the study was not associated with alterations in the gut microbiota composition in CKD patients. Further research on microbial sulfur pathways may provide a better understanding of the role of gut microbiota in maintaining H2S and lanthionine homeostasis.

Enhancing reliability in estimating modal parameters for automotive disk Brakes: A comprehensive approach using the Eigensystem Realization algorithm and additional criteria

This paper investigates the challenges in accurately identifying and assessing vibration characteristics in automotive disk brakes, which, due to their geometric symmetry, exhibit closely spaced vibration modes. Understanding the damping characteristics is crucial due to their significant impact on dynamic stability and the potential onset of brake squeal, as damping directly influences the stability threshold and its uneven distribution can destabilize the system. Therefore, this study primarily focuses on the identification of modal parameters with an emphasis on the damping of disk brakes. Traditional Experimental Modal Analysis (EMA) techniques, which rely heavily on Frequency Response Function (FRF) measurements, encounter challenges in distinguishing closely spaced modes, thereby affecting the reliability of parameter estimation, particularly damping. These algorithms are primarily based on FRF measurements and are of multi-input – single-output type (MISO). In comparison to Operational Modal Analyses (OMA) algorithms, which are widely used in civil engineering and are of the multi-input − multi-output type and contain statistical tools for assessing the uncertainty of the estimate, EMA provides limited possibilities to assess the quality of estimating parameters. The primary contribution of this work is demonstrating that the Eigensystem Realization Algorithm (ERA), supplemented with indicators such as Extended Modal Amplitude Coherence (EMAC), Modal Phase Collinearity (MPC), and the Consistent Mode Indicator (CMI), offers a robust tool for accurate damping estimation. Additionally, the application of ERA to data originally acquired for frequency-based methods, specifically the Rational Fraction Polynomial (RFP) method, allows for a direct comparison of these two EMA algorithms using the same dataset. The results demonstrate that the proposed identification process effectively distinguishes system modes from those influenced by noise, providing a pathway to optimize test data acquisition and improve the accuracy of modal parameter estimation, especially in systems with closely spaced modes. The method can also serve as a tool for optimizing the acquisition of test data to improve the estimation of modal parameters, by varying the positions of input (SIMO) or by transitioning to MIMO identification to enhance the observability and controllability of closely spaced modes of disk brake.

Evaluation of Environmental Risk from Heavy Metals in Sediments in Port Areas

This research aims to evaluate the concentration and distribution of heavy metals in sediment in the Port area of ​​PT Pelindo Dumai Branch, which is one of the main ports in Riau Province, Indonesia. Heavy metals such as cadmium, copper, lead, mercury and zinc are known to have significant toxic effects on maritime ecosystems and can accumulate in the food chain, potentially endangering aquatic life and human health. The research methodology involves taking sediment samples from various points around the port area, which are then analyzed using spectroscopic techniques to determine heavy metal concentrations. The results showed that the concentration of heavy metals in sediments varied, with zinc having the highest concentration (average 0.019724 mg/L), followed by copper, lead, cadmium, and mercury. This variation indicates the existence of diverse sources of pollution and uneven distribution in the port area. Although cadmium and mercury concentrations are relatively low, they still raise concerns due to their high toxicity and potential accumulation in the food chain. These results emphasize the need for more intensive environmental monitoring and targeted risk management to reduce the negative impacts of heavy metals on maritime ecosystems and human health. This research provides an important scientific basis for mitigation efforts in port areas, which are crucial to ensuring the sustainability of ecosystems and the well-being of communities that depend on marine resources.

Moisture dynamics during high‐load fluctuations in transformers: Localised accumulation and interfacial transfer within oil/pressboard insulation

AbstractPower systems grapple with the challenges of high load rates and intermittent new energy sources integration. Transformers, as vital equipment, employ oil/pressboard (oil/PB) insulation. Uneven moisture distribution in this insulation can jeopardise safety thresholds, necessitating precise moisture assessment for grid stability. A novel mathematical model, adsorption–desorption and porous media moisture transfer (ADP‐MoT), is presented. This model incorporates adsorption and desorption processes within the porous pressboard, enabling a description of the dynamic moisture transfer between the oil and pressboard. Using this mathematical model, simulations for moisture dynamics were performed on a 750‐kV transformer across four typical days. The results indicate that temperature fluctuations are the primary driving factor for moisture migration at the oil/PB interface. Convection and diffusion contribute to moisture movement towards cooler regions. Fluid properties and structural characteristics induce a distinctive streamline‐shaped moisture flow within horizontal oil channels, with localised moisture accumulation in specific areas. Moreover, the analysis of 96 transient results uncovers potential free‐state moisture formation during severe conditions, underscoring the importance of monitoring the pressboard at winding bases during high load fluctuations. In conclusion, this study significantly contributes to scientifically identifying and addressing risks tied to new energy sources integration in power systems.