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Item AI-based Surrogate Model for the Prediction of Ship Fuel Consumption Reflecting Hydrometeorological Conditions(2024) Zhang, Mingyang; Tsoulakos, Nikolaos; Kujala, Pentti; Hirdaris, Spyros; Department of Mechanical Engineering; Marine and Arctic Technology; Laskaridis Shipping Co. Ltd.; American Bureau of Shipping, GreeceAccurate prediction of ship fuel consumption is essential for optimizing ship performance and minimizing environmental impact. This study presents the development and validation of an artificial intelligence (AI)-based surrogate model specifically designed to predict Ship Fuel Consumption (SFC) in the case of a bulk carrier. The surrogate model employs a cutting-edge approach by combining deep learning techniques, specifically incorporating attention mechanisms into Bidirectional Long Short-Term Memory (Bi-LSTM) networks. This advanced model leverages a rich and diverse dataset comprising crucial operational parameters, including ship navigation, ship operational conditions, engine operational status, and Metocean data, to achieve highly accurate predictions of SFC. The dataset used for training and validation is sourced directly from realistic bulk carrier operations, ensuring the relevance and practical applicability of the model. Extensive generalization tests were conducted to evaluate the performance of the developed surrogate model. The results indicate that the AI-based surrogate model achieves long-term high accuracy in predicting ship fuel consumption under varying operational conditions. The developed surrogate model may serve as a valuable tool for bulk carrier operators, offering insights into fuel efficiency improvements and enhancing the overall sustainability of ship operations.Item Higher accuracy for smartphone positioning: post-processing, centre points and repetition(2023) Jussila, Anssi; Kettunen, Pyry; Nordman, Maaria; Department of Built Environment; Huang, Haosheng; Van de Weghe, Nico; Gartner, Georg; Geoinformatics; Finnish Geospatial Research InstituteThe importance of smartphone positioning for contemporary society is on the constant rise, as is the demand and potential for its higher accuracy. National mapping agencies see crowdsourcing by smartphone measurements as an interesting opportunity for data collection in the future. In this study, the purpose was to investigate the reality of smartphone positioning accuracy in the crowdsourcing context. The enhancement of plain real-time smartphone positioning was carried out by post-processing calculations with reference stations, centre point averaging and repeated measurements. The results were benchmarked against professional real-time kinematic measurements, and accuracies below 1.5 m were achieved at best by the mentioned techniques combined. The reached accuracy level is already useful for many mapping purposes and the latest developments in satellite positioning are still about to decrease measurement inaccuracies.Item Making logistics a central core in complex construction projects : a power-dependency analysis(Taylor & Francis, 2024) Fredriksson, Anna; Janné, Mats; Peltokorpi, Antti; Department of Civil Engineering; Performance in Building Design and Construction; Linköping UniversityIn complex projects, such as hospital constructions, there are large interdependencies between the actors involved, especially relating to the flow of materials and resources. As new hospital buildings are often built on existing blocks and campuses, ongoing hospital operations may hinder logistics and construction operations and vice versa. To handle these issues, it has become increasingly common to implement construction logistics setups (CLSs). The purpose of the paper is to analyse how the centrality of the CLS in the project organization affects the coordination and conflict level in complex construction project management using a power dependency lens. The study is based on case studies of six hospital projects in the Nordic countries. Based on a cross-case analysis it is identified that: 1) from a logistics management perspective we identify three different foci of the CLS; i) security for hospital patients and staff, ii) on-site material flow coordination, and iii) flow coordination to and from site, and 2) from a project management perspective the main findings point towards the importance of centrality of the CLS in the project management organisation in order to ensure enough power to mandate enforcement of coordination.Item Optimizing building hybrid energy systems for demand response marketplace operation(Elsevier BV, 2024-11-15) Savolainen, Rebecka; Einolander, Johannes; Lahdelma, Risto; Department of Mechanical Engineering; Department of Mathematics and Systems Analysis; Energy Conversion and Systems; Operations Research and Systems AnalysisIncreasing amounts of renewable power make it difficult to balance supply and demand in the grid. European Transmission System Operators invite consumers to participate in grid balancing through various demand response mechanisms. Individual buildings can contribute to grid balancing by reacting to dynamic electricity prices through implicit demand response. Buildings can also participate in explicit demand response programs, for instance through the Frequency Containment Reserve (FCR) market. This study presents a novel linear programming optimization model for implicit and explicit demand response operation of a building with a hybrid energy system including a ground source heat pump, district heating, power storage, heat storage, and which participates in the daily FCR market. The model is applied to the retrofit planning of an office building in subarctic Helsinki, Finland. The study compares four potential configurations, with and without power storage and with and without FCR trade. Results show that for the target building, FCR trade can save yearly about 3 % of the energy costs. Power storage was found to be cost-efficient only in conjunction with FCR trade.Item Effects of Static Strain Aging on Mechanical Performance of Ductile Cast Iron(Springer, 2024-10) Björklund, Ville; Hänninen, Hannu; Bossuyt, Sven; Department of Mechanical Engineering; Materials to ProductsEN-GJS-400-15U nodular cast iron intended to be used as load-bearing element in long-term geological disposal canisters containing spent nuclear fuel in Finland and Sweden was studied for static strain aging (SSA). Tensile test specimens manufactured from the nodular cast iron were pre-strained to 1%, 2% and 3% nominal plastic strains. The pre-strained specimens were aged at different temperatures ranging from room temperature to 400 °C for varying times. The aged specimens were tested with conventional tensile testing using constant cross-head speed of 0.016 mm/s. Additionally, four specimens were studied with digital image correlation (DIC) during the tensile testing to obtain full-field strain measurements. SSA resulted in elevated pronounced yield point in all the conditions, while the as-received material showed continuous yielding behavior. SSA reduced the elongation to fracture. DIC tests showed more localized yielding behavior in the SSA specimens. Over-aging effect was observed at 400 °C where increasing pre-strain did not increase the yield stress more. For 1-day aging time, the highest yield stress increment was found after aging at 200°C. The yield stress of the material was almost identical after aging in 100°C and 200°C.Item Teachers' facilitation of maker-centered activities : A framework for video analysis(2024-10-02) Aljabaly, Mariam; Aarnio, Hanna; Department of Mechanical Engineering; Materials to Products; University of HelsinkiVideo analysis as a methodological approach has the potential to clarify the complex classroom interaction between teachers and students during maker-centered activities. However, the development of a systematic approach for analyzing teachers’ actions in such context is still in its early phases. This poster presents a framework for analyzing teachers’ facilitation of design activities. To explore longitudinal video data from a maker-centered project of two teachers and two groups of students (n=6), we adapted the Making-Process-Rug method, originally intended to capture students’ design actions. We further developed the method to involve both students’ design actions and teachers’ verbal and embodied facilitation actions. The qualitative video analysis revealed differences in types and intensity of teachers’ facilitation in the different stages of the making process.Item Data-driven baseline generation for post-retrofit energy saving assessment, a comparison of statistical and machine learning methods(Elsevier, 2024-12-01) Kuivjõgi, Helena; Vasman, Sofia; Petlenkov, Eduard; Thalfeldt, Martin; Kurnitski, Jarek; Department of Civil Engineering; Performance in Building Design and Construction; Tallinn University of TechnologyThe renovation wave aims to improve energy performance of the existing building stock, encouraging development of methods for predicting post-retrofit energy use and quantifying savings. Therefore, establishing an energy use baseline is crucial for computing changes and savings. Data-driven techniques vary in effectiveness for this purpose. Selecting a suitable data-driven method for post-retrofit energy use modelling requires choosing between several approaches. This study compares two methods of establishing a baseline for post-retrofit evaluation, focusing on predicting heating and electricity energy use. One method utilizes monthly degree-day normalisation and baseline derivation, and the other employs machine learning techniques, including clustering to address seasonal variations and non-linear regression models like random forest and neural network. The comparison was based on CVRMSE, obtained by applying the methods to eight datasets. These individual datasets included metered and simulated data for heating and electricity energy use in two large non-residential buildings. An upper error margin of CVRMSE 25 % for annual energy use, as set in ASHRAE Guidelines, was not reached. The actual uncertainty during validation with simulated data ranged from 4.5 to 10.4 % for heating and electricity models using the degree-day method, and from 1.4 to 7.5 % for machine learning models. When applied to metered data, the degree-day method showed an uncertainty of 8.4–19.3 %, while machine learning models had an uncertainty of 6.11–17.5 %. Additionally, monthly percentage error analysis confirmed a considerably better performance of the machine learning models. This study contributes to the assessment of renovation impact and operational energy savings by offering additional perspectives on selecting energy use modelling methods, which are also applicable in the context of Minimum Energy Performance Standards.Item Reducing district heating carbon dioxide emissions with data center waste heat – Region perspective(Elsevier Ltd, 2025-02) Tervo, Seela; Syri, Sanna; Hiltunen, Pauli; Department of Mechanical Engineering; Energy Conversion and Systems; Department of Mechanical EngineeringClimate targets require district heating companies to decarbonize heat production as well as data centers to improve their energy efficiency and waste heat utilization. This study includes an energyPRO software modeling of a district heating network with a planned 21 MW data center in the Ostrobothnia region in Finland to investigate the effect of data center waste heat in a district heating network. Five future scenarios with assumptions on electricity, fuel and carbon dioxide prices were modeled to analyze the reduction of district heating carbon dioxide emissions with data center waste heat and related cost savings. The results indicate that carbon dioxide emissions decrease cost-effectively as waste heat replaces the use of high-emission peat. In scenarios with higher biomass prices, the emissions and costs decrease the most with waste heat utilization. Interviews conducted with stakeholders highlight that district heating companies should not be dependent only on one data center due to the volatile nature of the industry and the heat production costs. They also underlined that the data center is expected to improve local economic activity and the international network of the region. The interviews also indicate that broad local support for the data center can be achieved due to the emission reductions and positive impacts on local employment and the economy. The use of local peat fuel was widely understood to be phased out due to climate policy.Item User experiences of situational awareness systems in infrastructure construction(Taylor & Francis, 2024) Lappalainen, Eelon; Uusitalo, Petri; Seppänen, Olli; Peltokorpi, Antti; Ainamo, Antti; Reinbold, Ana; Department of Civil Engineering; Performance in Building Design and Construction; Structures – Structural Engineering, Mechanics and ComputationInfrastructure construction (IC) projects are dynamic, complex, and difficult to control and manage. Situational awareness (SA) systems have attracted growing interest in construction literature as an aid for human decision-making in order to forecast changes in project and operations situations. While technological advancements have been achieved in SA systems, very little empirical evidence exists on the actual experiences of IC professionals in relation to SA system usage. We interviewed 23 IC professionals to obtain data, which data we then analyzed by utilizing open coding. Based on our analysis, IC professionals adopt and integrate SA systems individually. On the other hand, often their SA exhibits a bias in favor of the subjective viewpoint of whoever is the dominant or responsible individual in their unit or team, and concealing facts by one or more people appears common. We thus conclude that SA systems can raise IC professionals’ awareness of a situation in ways that are objectively and easily visible and accessible to every individual. SA systems can also be used to conceal SA. This study contributes to earlier technology-focused research by revealing how the behavior of dominant individuals affects the user experience of SA systems.Item The effects of improved subsurface drainage on runoff and nitrogen leaching from a clayey field section(John Wiley & Sons, 2024-10) Jokinen, Vilma; Salo, Heidi; Mäkelä, Minna; Nurminen, Jyrki; Äijö, Helena; Laine-Kaulio, Hanne; Myllys, Merja; Koivusalo, Harri; Department of Built Environment; Water and Environmental Eng.; Aalto University; Finnish Field Drainage Association; Natural Resources Institute Finland (Luke); Drainage Research Association; Sven Hallin Research FoundationThe aim of this study was to investigate the effects of improved subsurface drainage installation on nitrogen (N) loss in drain discharge (DD) and topsoil layer runoff (TLR). Data on DD and TLR, as well as on concentrations of total, nitrate and ammonium N in the runoff components, were collected from four sections of an experimental field in southern Finland (June 2007–December 2018). Supplementary drains were installed in one of the field sections in June 2014, and the data from that section were compared with those from three reference sections. Differences between the sections were statistically analysed based on annual and monthly values of runoff components and concentrations, as well as the loads of N fractions. The results revealed that improved drainage increased the N load in the DD, reducing the load in the TLR. Changes in N loads were more clearly driven by changes in the runoff volumes rather than by changes in the N concentrations in the runoff waters. Before the drainage improvement, most of the total N load was nitrate (53%), while the share of rest N (fraction of the total N after the mineral N fractions were subtracted) was 45%. After improved drainage, the percentages of nitrate and rest N were 73 and 26%, respectively. The results demonstrate the importance of agricultural water management as the key driver for controlling nutrient loads.Item Fully automated extraction of railtop centerline from mobile laser scanning data(Elsevier, 2024-12-01) Kononen, Aleksi; Kaartinen, Harri; Kukko, Antero; Lehtomäki, Matti; Taher, Josef; Hyyppä, Juha; Department of Built Environment; MeMo; National Land Survey of FinlandDigitization is an important part of efficient infrastructure maintenance. Means to achieve a digital asset database include precise 3D surveys of the physical assets and advanced automated recognition of objects of interest for documenting, maintenance and further analysis purposes. To this end, fast data collection of railway infrastructure environments can be obtained using a mobile laser scanner mounted on a service locomotive, permitting uninterruptive service. This paper presents an algorithm that extracts the railtop centerlines of up to seven parallel tracks with a single measurement pass and achieves an accuracy of 0.3 cm to 0.8 cm on non-intersecting rails, which improves the state of the art by 55%–85%. On intersecting rails, the railtop location accuracy is comparable to that of existing methods. The proposed method uses only geometric data and performs in real time in two-track railroad configurations.Item Analysing the Environmental and Social Impacts of a Novel User-Based Transit Signal Priority Strategy in a Connected Vehicle Environment(John Wiley & Sons, 2024-10-15) Mohammadi, Roozbeh; Vosough, Shaghayegh; Roncoli, Claudio; Department of Built Environment; Planning and TransportationTransit signal priority (TSP) is a traffic control strategy aiming at prioritising public transit vehicles at signalised intersections. The emergence of connected vehicles (CVs) provides the opportunity to enhance TSP operation, mitigating challenges such as the negative impact on nontransit users and the management of conflicting priority requests. Furthermore, traffic control policies produce environmental impacts, whilst TSP strategies are typically evaluated based on common traffic flow indicators, such as average vehicle speed, delay and/or the number of stops. In light of the recent progress made in CV technology, we propose and assess two user-based TSP strategies. The first approach aims to minimise total user delay at a signalised intersection, whilst the second considers both reducing bus schedule delay and total user delay. We also measure the environmental effects of these TSP strategies. A microscopic simulation environment is used to compare the proposed methods’ performance against a conventional TSP ring-and-barrier controller in a case study involving two adjacent signalised intersections in Helsinki, Finland. The findings indicate that implementing the proposed strategies effectively enhances TSP performance whilst also lowering adverse environmental impacts.Item Computational fluid dynamics study of the atomic layer deposition process around cylindrical and planar configurations(Elsevier Ltd, 2023-08-05) Ersavas Isitman, Gizem; Izbassarov, Daulet; Puurunen, Riikka L.; Vuorinen, Ville; Department of Mechanical Engineering; Department of Chemical and Metallurgical Engineering; Energy Conversion and Systems; CatalysisComputational fluid dynamics (CFD) simulations were used to model atomic layer deposition (ALD) coating processes in the continuum flow regime. CFD model was validated for non-reactive and reactive flows. In ALD CFD simulations, surfaces in various test cases were considered as non-porous aluminum oxide. The effect of trimethylaluminium precursor partial pressure, initial condition, and Reynolds number (Re) on coating timescale were analyzed. The CFD model accurately captured the surface coverage solution for all cases when the domain was initially filled with the precursor. The absence of initial precursor delayed coating time during the surface concentration level development process. As Re increased, coating time significantly decreased due to reduced diffusion limitations and promoted convection swiftly transporting precursors to the surfaces. The provided example showed that 2D polydisperse fixed cylinder bed is fully coated within approximately one flow time through the bed. The benefits of CFD in understanding ALD processes were discussed.Item Sustainable wastewater treatment solutions for water-smart circular economy(2022) Aguado García, Daniel; Haimi, Henri; Mikola, Anna; Soares, Ana; Jeppsson, Ulf; Department of Built Environment; Water and Environmental Eng.; Polytechnic University of Valencia; Cranfield University; Lund UniversityThe Protection of aquatic water bodies and human health is a paramount objective accomplished by wastewater treatment systems. Traditionally, pollutants are managed and removed in wastewater treatment plants (WWTPs), following a paradigm in which wastewater is considered a waste. Wastewater treatment requires significant amounts of resources, such as energy and chemicals, while sludge is produced, requiring further treatment. A decade ago, a new paradigm emerged, suggesting that municipal wastewater is a source of resources, particularly reclaimed water, materials (e.g., nutrients) and energy. Many processes applicable for this new paradigm already existed, and others have been further developed (struvite-crystallization, membrane contactors, air-stripping, ionic exchange, electrodialysis, direct osmosis, etc.). Recently, resource recovery processes have been extensively developed and investigated to optimize their operation. Reclaimed water can be used for recharging aquifers, irrigation in agriculture and cooling applications. Potential risks posed by the use of reclaimed water – and of other recovered wastewater resources – must be assessed and managed during the lifecycle of the application. For example, membrane separation processes are recognised as suitable for this application to remove pathogens and particles to ensure water quality. Traditional WWTP design is based on effluent quality requirements and investment costs, with energy efficiency being only rarely considered. Larger facilities exhibit lower normalized electric consumption than smaller WWTPs, and older ones normally consume more than modern facilities (although is process dependent). For instance, in Spain it is possible to find facilities with specific electric consumptions 5-10 times higher than in modern and optimized facilities. This clearly reflects the great margin for potential energy savings. Electricity consumption at WWTPs can be reduced by improving the processes and their operation, as well as through mechanical equipment improvement. The aeration of the biological process is the major electricity consumer; thus, control strategies have been deployed to its optimization. Also, less oxygen-demanding process alternatives have been explored, like the simultaneous nitrification-denitrification operated at very low dissolved oxygen concentration. Partial nitritation and deammonification processes with low oxygen consumption per nitrogen load removed, are especially suited for treating supernatant from sludge dewatering units. However, these low energy solutions might have a downside with direct greenhouse gas GHG emissions, especially N2O. Anaerobic digestion of sludge, usually applied in large WWTPs, produces biogas that can generate both electricity and heat for local use or external use, through combined heat and power production, or liquefied biogas for external use. It is also possible to increase biogas production through co-digestion of external substrates, advanced control or sludge pretreatment. Thermolysis processes, piloted for sewage sludge treatment, enable also waste-tochemicals applications. There are also other possibilities for energy recovery at WWTPs, such as thermal energy via heat exchangers and heat pumps, hydropower generation using turbines, and heat from sludge incineration. Energy can be also recovered by anaerobic digestion of microalgae grown in nutrient-rich wastewater. In this paper, the transition towards sustainability and water-smart circular economy is illustrated showing how current WWTPs can be turned into Water Resource Recovery Facilities (WWRFs). The incorporation of sustainable pathways and technologies, makeenergy-positive facilities achievable, thus, reducing their climate impact.Item Ammonia as a sustainable fuel: Review and novel strategies(Elsevier Ltd, 2025-01) Cheng, Qiang; Muhammad, Akram; Kaario, Ossi; Ahmad, Zeeshan; Martti, Larmi; Department of Mechanical Engineering; Energy Conversion and Systems; Energy Conversion and Systems; Wärtsilä CorporationAmmonia is increasingly recognized as a viable alternative fuel that could significantly reduce greenhouse gas emissions without requiring major modifications to existing engine technologies. However, its high auto-ignition temperature, slow flame speed, and narrow flammability range present significant barriers, particularly under high-speed combustion conditions. This review explores the potential of ammonia as a sustainable fuel for internal combustion engines, focusing on its advantages and challenge. The review draws on a wide range of studies, from NH3 production, application, to the combustion mechanisms, that explore various strategies for enhancing NH₃ combustion in both spark ignition and compression ignition engines. Fundamentals and key approaches discussed include using hydrogen and hydrocarbon fuels as combustion promoters, which have been shown to improve ignition and flame propagation. Literature on fuel injection strategies, such as port fuel injection, direct injection, and dual-fuel injection, are examined to highlight their influence on NH₃-air mixing and combustion efficiency. Furthermore, the review delves into advanced ignition technologies, such as low-temperature plasma ignition, turbulent jet ignition, and laser ignition, which are explored for the potential to overcome the ignition difficulties associated with NH₃. After a comprehensive analysis based on the literature, the intelligent liquid-gas twin-fluid co-injection system (iTFI) emerges as a promising approach, offering improved combustion stability and efficiency through better fuel-air mixture preparation. By synthesizing the existing research, this review outlines the progress made in NH₃ combustion and identifies areas where further study is needed to fully realize its potential as a sustainable fuel.Item Determination of the moment–rotation relation of continuous timber–concrete composite floors based on the component method(Elsevier Ltd, 2024-11) Krug, Sebastian; Jaaranen, Joonas; Fink, Gerhard; Schänzlin, Jörg; Department of Civil Engineering; Structures – Structural Engineering, Mechanics and Computation; University of Applied Sciences BiberachTimber–concrete composite (TCC) combines the advantages of timber and reinforced concrete construction. In multi-storey buildings, the design of TCC floors is often governed by the deformation serviceability requirements. One way to improve deformation serviceability is through the design of continuous floor systems. However, the current practice of TCC slab systems is often limited to load-carrying as single-span beams. This paper presents an analytical model based on the component method for determining the moment–rotation relation of continuous TCC slabs in the range with negative bending moments. The investigations involve the development of load–displacement curves for the individual force-transmitting components, including timber and reinforced concrete, followed by their assembly into a component model. The model has been verified using finite element calculations and the results demonstrate that the moment–rotation relation of continuous TCC systems can be accurately captured. As the variability of the material properties strongly influences the stiffness of the joint and therefore the deformation and stresses in the TCC slab, a probabilistic analysis of the material parameters was performed using the Monte Carlo method. The probabilistic investigations show that the variability of the input parameters has a significant impact on the joint stiffness, with notable scattering observed in the moment–rotation relation, especially in the range of the cracking phase of the concrete. The results from the probabilistic investigations enable initial statements about the joint stiffness of continuous timber–concrete composite slabs in ranges with negative bending moments.Item Paradigm shift in mechanical system design : toward automated and collaborative design with digital twin web(Springer, 2024-10-03) Ala-Laurinaho, Riku; Autiosalo, Juuso; Laine, Sampo; Hakonen, Urho; Viitala, Raine; Department of Mechanical Engineering; MechatronicsAnalyzing multi-vendor mechanical system designs requires a significant amount of manual work, resulting in a design paradigm where analysis is conducted only after the design is locked and components are selected. This leads to a suboptimal design with compatibility issues, over-dimensioned components, inferior performance, poor energy efficiency, and a lack of collaboration between OEMs (original equipment manufacturers) and system integrators. To overcome these issues, this paper proposes Co-Des (collaborative design) framework for automated and collaborative multi-vendor system design. The framework relies on standardized digital twin documents (DTD) of system designs, components, and analyses. The discoverability and distribution of these DTDs are enabled with digital twin web (DTW). Co-Des framework allows for finding suitable components for the design task by automatically running selected analyses employing component digital twins. In addition, OEMs can provide customized components for system integrators using the initial system design defined in the system design DTD. The use of the Co-Des framework was demonstrated with a windmill powertrain design use case, and the applicability of the automated assembly analysis for component selection was verified with performance measurements. The adoption of the proposed framework will lead to a paradigm shift from manual and siloed work relying on the exchange of PDFs to a more automated and collaborative design of mechanical systems. The adoption rate is defined by the willingness of system integrators to publish their initial system designs and OEMs their components as public digital twins.Item Campylobacter species, Salmonella serotypes and ribosomal RNA-based fecal source tracking in the Kokemäki River watershed(Elsevier Science B.V., 2024-12-01) Hokajärvi, Anna Maria; Tiwari, Ananda; Räsänen, Pia; Wessels, Laura; Rankinen, Katri; Juntunen, Janne; Grootens, Rudolf J.F.; Kuronen, Henry; Vepsäläinen, Asko; Miettinen, Ilkka T.; Huttula, Timo; Pitkänen, Tarja; Department of Built Environment; Water and Environmental Eng.; Finnish Institute for Health and Welfare (THL); Finnish Environment Institute; Finnish Food AuthorityFecal contamination of surface water compromises the usability of surface water for drinking water production due to an increase in human health risks. In this study, we collected surface water samples for two years from the Kokemäki River (Finland). The downstream river stretch is used for feeding production of artificial ground water for a major drinking water treatment plant. The prevalence of Campylobacter species and Salmonella serotypes together with fecal source identifiers targeting general, human, gull, swine, and ruminant were evaluated at 16 sampling sites throughout the studied watershed. We detected Campylobacter spp. from all 16 sampling sites with Campylobacter jejuni and Campylobacter lari as the most detected species. Salmonella spp. was detected in 10 out of 16 sampling sites, with Salmonella Typhimurium being the most common serovar. Regarding spatial variation in the hygienic quality of surface water, the upstream area (urban proximity) and downstream area (agricultural proximity) had higher microbial loads than the middle section of the study area. Samples taken in fall and spring had higher microbial loads than summer and winter samples. The lower ratio of rRNA to rRNA-gene (rDNA) of studied microbes in the winter than in other seasons may indicate low metabolic activity of bacterial targets during winter. The number of gulls, swine, and cattle in the catchment area concorded with the number of fecal source identifiers in the surface water. Further, the prevalence of gull-specific source identifier agreed with the detection of C. coli, C. lari, and S. Typhimurim, whereas the prevalence of swine- and ruminant-specific source identifiers agreed with the detection of C. jejuni and C. coli. Thus, fecal source identifiers are shown to be important tools for monitoring zoonotic pathogens affecting microbial quality of surface water. Further, variation in fecal loads indicates such variation in health risks related to surface water use.Item Electrochemical performance of graphene oxide synthesized from graphitic spent potlining for energy storage application(Elsevier BV, 2024-11-10) Dzikunu, Perseverance; Arthur, Emmanuel Kwesi; Gikunoo, Emmanuel; Mensah-Darkwa, Kwadwo; Akinwamide, Samuel Olukayode; Fangnon, Eric A.K.; Vilaça, Pedro; Department of Mechanical Engineering; Materials to Products; Kwame Nkrumah University of Science and TechnologyThe hazardous nature of spent pot lining (SPL) generated from aluminum smelters poses environmental challenges due to its high fluoride and cyanide content. However, techniques and recent studies have shown that SPL can be converted into valuable carbon-based materials through innovative recycling with potential applications in energy storage devices. This work presents an electrochemical performance evaluation of graphene oxide (GO) electrodes derived from acid-treated SPL for supercapacitor applications. The SPL-derived graphene oxide (SPL-GO) was synthesized via a facile and scalable improved Tour method. SPL-GO electrodes were fabricated by drip-coating SPL-GO/PVDF/DMF suspension on nickel foams. The morphology, structure, and chemical composition of the SPL-GO were characterized using advanced techniques such as energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD). The electrochemical properties of the SPL-GO in 3 M KOH were characterized with a three-electrode system using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. The results demonstrate that SPL-GO exhibits a relatively high specific capacitance of 762.90 F/g at 1 A/g with corresponding power and energy densities of 502 W/kg and 106.60 Wh/kg, respectively. Additionally, excellent cycling stability of 85.4 % was achieved after 10,000 cycles with a coulombic efficiency of 95.23 %. These results suggest a superior rate capability of SPL-GO, rendering it a viable candidate for supercapacitor applications. Furthermore, this work sets the foundation for the sustainable use of industrial waste in energy storage devices, suggesting a novel, eco-friendly material for practical supercapacitor applications.Item DEEP RECURRENT NEURAL NETWORK ALGORITHM FOR ACTIVE SOUND QUALITY CONTROL OF WIPER-WINDSHIELD FRICTION NOISE(2024) Guo, Hui; Fan, Huizhi; Wang, Yansong; Ma, Minghui; Huang, Shuang; Liu, Ningning; Cheng, Qiang; Department of Mechanical Engineering; van Keulen, Wim; Kok, Jim; Energy Conversion and Systems; Shanghai University of Engineering ScienceThe effectiveness of traditional Adaptive Noise Equalizer (ANE) algorithm and its extension algorithms for Active Sound Quality Control (ASQC) systems is unsatisfied in engineering application, especially for the nonlinear problems. In this paper, a nonlinear active sound quality control algorithm based on Deep Recurrent Neural Network (DRNN) is proposed for the wiper-windshield friction noise. A DRNN model based on Long Short-Term Memory (LSTM) neutral network is constructed to perform nonlinear mapping on the input signal through setting an objective function. The trained output secondary signal is counteracted with the expected signal to obtain the minimum error signal. Thus, the linear filter in traditional algorithms is replaced by the proposed DRNN model. Setting the wiper-windshield friction noise of an actual vehicles as the input signal for the DRNN algorithm, simulation analysis was conducted. The results were compared with the input original signal in terms of control effectiveness in both time-domain and frequency-domain. Meanwhile, the psychoacoustic attribute metrics such as loudness, roughness, and sharpness are calculated for the simulating output signals. The results demonstrate that the proposed DRNN active sound quality control algorithm has a good control effect on the wiper-windshield friction noise, especially for the frequency range of 0-500Hz, which is 67.39%, 62.58%, and 56.38% lower than the original noise in terms of loudness, roughness, and sharpness, respectively. The amplitude of the noise is simultaneously reduced. Therefore, the proposed algorithm has significant advantages in improving the vehicle interior sound quality by controlling the wiper-windshield friction noise.