bluuebunny/crossref_metadata_2025 huggingface dataset:
GEOCHEMICAL, MINERALOGICAL, AND PETROGRAPHICAL STUDIES OF IRONSTONES AROUND MOUNT PATTI, SOUTHERN BIDA BASIN, NIGERIA: IMPLICATIONS FOR QUALITY ASSESSMENT, PROVENANCE AND ENVIRONMENT OF DEPOSITION
Authors: Ayuba R. , Baba Y. , Adamu L. M. , Ochu G. D. , Ebe A. , Emmanuel A. U.
Published: March 2024

The mineralogical composition, geochemistry, and depositional environment of the ironstone exposed on Mount Patti in the southern Bida Basin of Nigeria were assessed using integrated geochemical, mineralogical, and petrographic techniques. X-ray fluorescence spectrometry, X-ray diffraction, and transmitted light microscopy were used in geochemical, and petrographical investigations of fourteen representative ironstone samples. Average chemical analysis results showed that the concentrations of SiO2 (5.93 wt%), TiO2 (0.09 wt%), Al2O3 (10.76 wt%), and Fe2O3 (77.47 wt%) were as follows. The ironstone may be found in a shallow marine environment or non-marine environment if the concentrations of CaO, Na2O, K2O, MnO, and CuO are less than 0.40. This assertion is supported by the absence of sulfur oxide (SO3) in the examined samples and the bivariate plot of SiO2 versus Al2O3 and triangular plot of Fe-Mn-(Cu+Zn). Low levels of CaO and the absence of CO3 indicate that the environment is oxidizing. The iron's grade was calculated and found to be approximately 54.180%, which has been classified as low grade. The study also revealed that the ironstone contains a high amount of gangue materials (Al2O3 and P2O5), its silica (SiO2) content is within permissible limits, and it is devoid of harmful materials like sulfur. Based on petrographic studies, the floating contact displayed by the framework grains indicates that the iron cements were eodiagenetic in origin. Although it can be used more effectively as cast iron, sufficient beneficiation (to remove excess silica) can make it useful for iron and steel production.
EXPLORING THE POTENTIAL OF MORINGA OLEIFERA EXTRACT AS A NATURAL TISSUE FIXATIVE FOR HISTOPATHOLOGICAL APPLICATIONS
Authors: Chiwar Hassan , Alkali A. T. , Musa A. I. , Umar H. B.
Published: March 2024

Histopathology, crucial for disease diagnosis, heavily relies on effective tissue fixation to maintain cellular architecture. However, the carcinogenic nature of formalin has spurred interest in safer alternatives. Moringa oleifera, renowned for its medicinal properties, presents a promising natural fixative candidate. This study aimed to assess Moringa oleifera extract's viability as a fixative for histopathological applications, specifically focusing on its compatibility with subsequent histological analyses. Distilled water and normal saline solutions of Moringa extract were prepared at varying concentrations. Kidney tissue samples from euthanized rats were treated with these solutions alongside formalin. Tissue sections underwent manual processing, embedding, sectioning, and staining using Hematoxylin and Eosin (H&E) technique. Microscopic examination revealed varying degrees of tissue preservation across Moringa concentrations and solvents. Higher concentrations (15%) in distilled water exhibited optimal preservation, akin to formalin-fixed tissues, while lower concentrations and normal saline solutions showed suboptimal fixation. These findings highlight Moringa oleifera's potential as a tissue fixative, particularly at higher concentrations in distilled water. Further research is recommended to isolate active components and explore alternative Moringa extracts for enhanced tissue preservation. Comparative studies would elucidate the efficacy of Moringa-derived fixatives and inform their utilization in histopathological practice.
A gyalogtúrázás egészségvédő hatásai
Authors: Kozma Tímea , Baba Erika
Published: March 2024

Nowadays, health-conscious lifestyle is getting more and more attention, so the popularity of active sports tourism, including walking tourism, is constantly increasing. The aim of our research was to examine the health-promoting effects of hiking among hikers in general. In our primary research, we asked regular hikers what changes they experienced in their physical and mental state and social relationships as a result of regular hiking. An online questionnaire survey was conducted, the data of which were analyzed using SPSS statistical program (frequency, mean, standard deviation, chi-squared test). A total of 491 people filled out questionnaire, 35% of whom go hiking every week. Among respondents who do not do other sports besides it (39%), 38% hike on a weekly basis. Since regular hiking, some respondents reported weight loss, improved fitness and endurance, and a decrease in those with high blood pressure and high cholesterol. Two-thirds of the respondents relaxed while hiking – and thanks to this and nature's calming environment – they felt relaxed while hiking, and this calmness was also felt after hiking. More people also experienced creativity during everyday life and more people began to live in conscious presence than before regular hiking. As a result of hiking, there were several positive changes in the social relationships of the respondents; half of the respondents reported that they made friends while hiking, and even more said hiking improved their relationship with the friend/family member who they hiked with.
Mapping the trajectory of organizational leadership development: A bibliometric analysis
Authors: Talukder Saurav Chandra , Miah Md Tota
Published: March 2024

This research analyzes scholarly literature on the topic of leadership development as it relates to the fields of business and management. The researchers conducted a comprehensive search of the Web of Science database covering a 15-year time frame using the PRISMA methodology, ultimately yielding 1017 documents for analysis. Biblioshiny, and VOSviewer were used for quantitative analysis and data visualization, respectively. The study provides valuable information, such as the most influential authors and their nations, the most important keywords, and the most cited scholarly works in the topic. In addition, it reveals active research areas and literature gaps that point to potential new lines of inquiry. In highlighting the managerial and structural consequences of enhancing leadership within companies, the findings provide a useful basis for policymakers and practitioners.
Enhancing sustainable practice in social housing delivery
Authors: Makalima Mzuchumile
Published: March 2024

This paper explores sustainable practices in social housing delivery in Soweto, South Africa, and their influence on urban development. The research aims to assess the current state of sustainable practices and identify challenges and opportunities for enhancing sustainability. Through interviews with government officials, community leaders, young residents, and construction experts, this paper shows existing sustainable initiatives, such as solar panels and recycling, driven by government policies. However, challenges, including budget constraints and the need for community education, persist. Recommendations emphasize collaboration, clear communication, community engagement, and local resource utilization. This study contributes to the ongoing discourse on sustainable urban development, offering insights that can guide Soweto toward a greener and more inclusive future.
Logisztikai kihívások az autóiparban 2020–2023
Authors: Molnár László , Tégla Zsolt
Published: March 2024

A 2020-as évektől nagy kihívásokkal találta magát szemben az autóipar. A Covid-19 jelentősen megváltoztatta az ellátási láncok működését, az addig kiszámítható beszerzési és elosztási rendszerek teljes egészében bizonytalanná váltak. Szükség volt a logisztikai folyamatok áttervezésére. Az ezt megelőző időszakban jól alkalmazható logisztikai módszerek - (JIT, JIS, ABC elemzésen alapuló beszerzési stratégiák) amelyek az iparra jellemző sajátosággal rendelkeztek és segítették a Lean alapú gyártást a készletszintek csökkentését és a pontos szállításokat - felhasználásukat tekintve a változó gazdasági környezet miatt hatékonyságuk csökkent és vagy átalakult. 2022-ben az Orosz-Ukrán háború és az azt követő időszak energiaválsága újabb feladatok elé állította az autóipari logisztikai rendszereket. Ezen tényezők miatt a logisztikai folyamatokban jelentős átalakulások következtek be, hiszen az állandóan változó gazdasági környezet, a hektikusan alakuló energiaköltségek és a munkabérek jelentős növekedése a stratégiai szint mellett az tervezési és operatív folyamatok pontos és naprakész mérését és kontrollját tette szükségessé. A gazdasági teljesítő képesség mellett megjelentek olyan a túlélést biztosító tulajdonságok az autóipari vállalkozásoknál, mint a rugalmasság, az alkalmazkodó képesség, a modularitás vagy a nagyobb rendszerekbe való kapcsolódás és beágyazódottság képessége. Mindezen tulajdonságok megléte már alapvető szükséglet az autóipari folyamatok zavartalan működéséhez. A korábban működő logisztikai szabályokat újra kellett a vállalkozásoknak gondolni, így a Kühne+Nagel Kft-nek is, mint logisztikai szolgáltatónak tanulva az elmúlt 3 év gazdasági változékonyságaiból másfajta módon kell meghozni a stratégiai döntéseit. 2023-ban újabb hosszú távú kihívások elé állították az autóipari beszállítókat és logisztikai szolgáltatókat, hiszen az elektromos autóipari folyamatokra való felkészülés és átállás teljesen más alkatrészek és készletezési rendszerek valamint beszállítók megjelenését hozta magával.
Covid-19 And The Level of Awareness of Vitamin D Among Saudi Population – A Cross-Sectional Study of Dental Public Health Perspective
Authors: Moothedath Muhamood , Al Harbi Fahad Naif
Published: March 2024

Introduction: Vitamin D is a fat-soluble vitamin of importance necessary for calcium homeostasis, healthy bones, and prevention of fractures. It has also been linked to many metabolic, infectious and autoimmune diseases. Vitamin D levels are also being studied with respect to oral health issues such as dental caries, and periodontitis. Vitamin D deficiencies have been found to be relatively common among Covid-19 patients and who received supplements experienced less severe symptoms. The credible proposals for vitamin D supplementation to avoid infection and mortality due to Covid-19 validate the chance of raising public awareness on significance of its health benefits. Thus, we carried out this research to study the influence of Covid-19 on Saudi Arabian population's awareness of vitamin D with a dental public health perspective.
Materials and methods: A cross-sectional study of the Saudi Arabian general population was undertaken with 240 subjects, including men and women chosen at random varying a range of age groups from 18 to 74 years after consent and institutional approval. Sample size was computed using G-power software. Pretested, validated questionnaire, translated to Arabic was disseminated through e-mails and all prominent social medias. Statistical analysis was done using statistical package for the social sciences (SPSS) version 26.0. Bivariate analysis was performed using chi-square test at 5% significance level.
Results: Out of 240 people participated; 57% were men, and 43% were women. Majority were between the ages of 18 and 30 years. 65% of the participants were aware that vitamin D is important for bone health, supports oral health, reducing tooth decay, and lowering the risk of heart disease. Half of the study population believe that the sunlight is the prime source of vitamin D and 80% assumed that the ideal time of sunshine exposure is in the morning. 88.3% of them projected the need to increase their knowledge about vitamin D.
Conclusion: There was a lack of awareness and knowledge about vitamin D and its significance for the body and teeth, as well as its relationship to Covid-19. The pandemic had no significant impact on society's awareness about vitamin D. This study emphasises the importance of raising awareness among the public about vitamin D and ways to prevent its deficiencies.
Bangladesh Journal of Medical Science Vol.23 (Special Issue) 2024 p.S66-S72
Comparative Evaluation of Debris Extrusion, Remaining Dentin Thickness and Fracture Resistance of Endodontically Treated Teeth Using Rotary and Reciprocating Endodontic File Systems: An In Vitro Study
Authors: Khanvilkar Unmesh , Dhok Vaishnavi , Misra Rashmi , Pagariya Gunjan , Agarwal Rolly S , Deshpande Sharvaree
Published: March 2024

Background: Endodontic treatment aims to thoroughly clean and shape the root canal system while preserving the structural integrity of the tooth. The choice of endodontic file system can significantly impact the outcomes of this procedure. This in vitro study compares debris extrusion, remaining dentin thickness, and fracture resistance in endodontically treated teeth using rotary and reciprocating endodontic file systems.
Materials and Methods: Forty extracted human mandibular premolars were selected and randomly divided into two groups (n=20 each): Group A was prepared using a rotary file system, and Group B was prepared using a reciprocating file system. Debris extrusion was quantified using the Myers and Montgomery method, and remaining dentin thickness was measured at the coronal, middle, and apical thirds of each root. Fracture resistance was evaluated using a universal testing machine. The data were analyzed using appropriate statistical tests.
Results: The mean debris extrusion in Group A was 0.25 mg, while in Group B, it was 0.18 mg. The remaining dentin thickness in Group A was 1.24 mm, 1.15 mm, and 1.06 mm at the coronal, middle, and apical thirds, respectively, while in Group B, it was 1.30 mm, 1.22 mm, and 1.14 mm. The mean fracture resistance in Group A was 888 N, and in Group B, it was 920 N.
Conclusion: The reciprocating endodontic file system exhibited less debris extrusion, slightly greater remaining dentin thickness, and slightly higher fracture resistance compared to the rotary file system, although these differences were not statistically significant. Both file systems can be considered safe and effective for endodontic treatment, with the choice depending on clinician preference and specific clinical scenarios.
Bangladesh Journal of Medical Science Vol.23 (Special Issue) 2024 p.S87-S91
Prevalence and Predictors of YouTube Use among Undergraduate Medical Students: A Cross Sectional Study from a Medical School of Riyadh, Saudi Arabia
Authors: Saleh Aldobekhi Faris Suleiman
Published: March 2024

Introduction: The use of YouTube has increased now among medical students to revise the curricular content, to better understand them and also to share ideas. This study was carried out to find out the prevalence and predictors of use of YouTube by medical students.
Methodology: A cross-sectional study was carried out to assess the prevalence and predictors of use of YouTube as an extracurricular way of enhancing learning experience among medical students of Saudi Arabia for a period of 06 months from February 2023 to July 2023. A pre-validated self-administrated questionnaire consisting of the following sections like sociodemographic details, the predictors for the use of YouTube videos which consisted of frequency of use, grading of its usefulness etc. was used for data collection. Templates were generated in MS Excel sheet and analysis of data was done using SPSS software version 22. Quantitative variables were presented as frequency and percentages while chi square test of significance was used to demonstrate the associated between categorical variables. The value of significance was set as p less than 0.05.
Results: The prevalence of use YouTube was 94.1% among medical students in a medical school of Saudi Arabia, out of which 73.8% use it for both educational and entertainment purpose and about 71% of them find it very useful for educational purpose. About 43.7% of students use directed search strategy and most opined that it helped in better understanding. Most students use YouTube for upto one hour. Male students of age group 20 – 22 years were more involved in using YouTube videos as compared to female students or of other age groups and this association was statistically significant.
Conclusion: YouTube use is highly prevalent among medical students to better understand the subject matter and to revise them. Male students use them more often as compared to female students.
Bangladesh Journal of Medical Science Vol.23 (Special Issue) 2024 p.S122-S126
Empirical Examination of Stakeholders Engagement as A Predictor of Corporate Reputation
Authors: AJALIE, Nwannebuife Stanley , Sharma AARTI , Sylvanus Francis UDOH , Emieseifa James AGAMA
Published: March 2024

This study examined the impact of stakeholders' involvement on the corporate reputation of telecom service providers in Lagos, Nigeria. The four main telecom service providers in Nigeria—MTN, Globacom, Airtel, and 9Mobile—make up the study's population. 1200 users of telecom services and goods were chosen at random using practical sampling methods comprised the sample size. The instrument for the survey was a well-structured questionnaire designed to gather pertinent data. A total of 1003 questionnaires were recovered from the 1200 that were dispersed. The structural equation model (SEM) and the statistical package for social sciences (SPSS) were used to analyze data. Findings from the study revealed that stakeholders’ involvement has a significant effect on corporate reputation at (R=.447, R2=.199 at p=0.000). The statistical results show that there is a strong relationship between stakeholders’ engagement and corporate reputation and that stakeholders’ engagement accounts for 19.9% of variations in corporate reputation. The results demonstrated that corporate reputation is significantly impacted by stakeholders' engagement. According to the report, telecommunication companies should cultivate positive connections and trust with their stakeholders because these factors are essential to the organization's aims and objectives being successfully attained.
Development of the Evaluation of Teaching Performance in Basic Education
Authors: Lavado-Antonio Rosario Isabel , Robles-Huanhuayo Mariadela Giselle , Peña-Flores Viviana Soledad , Borda-Andia Angelica Rosario , Carpio-Mendoza Janet
Published: March 2024

The evaluation of teaching performance is a process of reflection and improvement that provides the necessary mechanisms for teachers to improve the quality of education. The purpose of this study is to analyze the development of teacher performance evaluation in elementary education. The study method used was argumentative criticism based on an analysis of the literature on the subject. Thus, the approach (introduction), development (arguments), and conclusions are presented. As a conclusion, it has been obtained that the evaluation of teaching performance allows the optimization of resources and instruments in teaching practices. In this sense, it helps teachers to make decisions to improve their teaching.
Resveratrol Attenuates Rheumatoid Arthritis Induce Neutrophil Extracellular Traps via TLR-4 Mediated Inflammation in C57BL/6 Mice
Authors: Chen Z , Xiao G , Ao J
Published: March 2024

The objective of this study was to evaluate whether RSV inhibits neutrophil extracellular traps (NETs) that induce joint hyperalgesia in C57BL/6 mice after adjuvant-induced arthritis. A subplantar injection of Freund's complete adjuvant was administered to C57BL/6 mice on day 0 for immunization in the AIA model. Resveratrol (RSV, 25 mg/kg) was administered intraperitoneally once daily starting on day 22 and continuing for two weeks. The effects of mechanical hyperalgesia and edema formation have been assessed in addition to histopathological scoring. Mice were sacrificed on day 35 to determine cytokine levels and PADI4 and COX-2 expression levels. ELISA was used to quantify neutrophil extracellular traps (NETs) along with neutrophil elastase-DNA and myeloperoxidase-DNA complexes in neutrophils. An immunohistochemical stain was performed on knee joints to determine the presence of nuclear factor kappa B p65 (NF-κB p65). AIA mice were found to have higher levels of NET in joints and their joint cells demonstrated an increased expression of the PADI4 gene. Treatment with RSV in AIA mice (25 mg/kg, i.p.) significantly (P<0.05) inhibited joint hyperalgesia, resulting in a significant increase in mechanical threshold, a decrease in articular edema, a decrease in the production of inflammatory cytokines, increased COX-2 expression, and a decrease in the immunostaining of NF-κB. Furthermore, treatment with RSV significantly reduced the amount of neutrophil elastase (NE)-DNA and MPO-DNA complexes, which were used as indicators of NET formation (P<0.05). This study indicates that RSV reduces NET production and hyperalgesia by reducing inflammation mediated by PADI4 and COX-2. According to these data, NETs contribute to joint pain and resveratrol can be used to treat pain in RA through this pathway.
Optical Insights into Fibrotic Livers: Applications of Near-Infrared Spectroscopy and Machine Learning
Authors: Addissouky Tamer A. , El Sayed Ibrahim El Tantawy , Ali Majeed M. A. , Alubiady Mahmood Hasen Shuhata
Published: March 2024

Background: Liver fibrosis staging is critical for patient selection and management prior to transplantation, but biopsy is invasive and serum biomarkers lack accuracy. Near-infrared spectroscopy (NIRS) is an emerging non-invasive technology that can detect liver fibrosis via changes in tissue composition. Machine learning (ML) enables analysis of NIRS data for diagnostic modeling.

Purpose: To review the potential of NIRS-ML approaches for rapid, point-of-care liver fibrosis detection, including technological principles, promising applications, current limitations, and future directions.

Main body of the abstract: NIRS leverages unique near-infrared absorbance patterns reflecting collagen accumulation, lipid reduction, and other chemical alterations in fibrotic liver. Handheld/hyperspectral systems acquire tissue spectroscopic data in minutes. Multiple human studies correlate NIRS with histological fibrosis scores. ML techniques like partial least squares regression, neural networks, support vector machines, and random forests analyze spectra to develop optimized diagnostic algorithms. Initial models differentiate mild versus advanced fibrosis and stage cirrhosis with high accuracy, outperforming traditional biomarkers. Recent advances include smartphone-based scanning, cloud computing, and integrated user-friendly platforms. However, further large validation trials, standardization, assessment of confounding factors, improved ML methodology, and cost-effectiveness data are required before widespread clinical implementation.

Conclusion: With ongoing research to address remaining barriers, NIRS-ML approaches hold great disruptive potential for rapid, non-invasive point-of-care quantification of liver fibrosis, including optimizing transplant surgery planning and management.
The Legality of Brushing Practices in the Viewpoint of Consumer Protection Law and Telematics Law
Authors: Swarianata Vifi , Puluhulawa Jufryanto , Apripari Apripari , Kaku Rismanto , Puluhulawa Irlan
Published: March 2024

Instant profit-making patterns have been established by the current online purchasing and selling practices. For example, brushing is the activity of internet retailers or merchants fabricating favorable reviews or fraudulent endorsements to boost the reputation of their goods or services. When a customer receives a product or service that falls short of their expectations, brushing can be harmful. This study aims to investigate the legality of online buying and selling in Indonesia, specifically the practice of "brushing," or using fictitious orders, reviews, and buyers.  The methods used are Statute Approach, Case Approach, Conceptual Approach, Analytical Approach, Theoretical Approach.   The findings indicated that, from the standpoint of Indonesian telematics and consumer protection legislation, brushing activities frequently contravene a number of relevant rules and laws. As a result, brushing may be deemed unlawful in Indonesia and subject to penalties based on relevant legislation. In order to prevent brushing activities, it is critical that the government and regulatory agencies bolster law enforcement, protect consumers from brushing practices, and inform consumers of their rights in this regard. Enforcing stringent regulations and ensuring their efficient implementation are crucial for safeguarding consumers and upholding the integrity of Indonesia's online ecosystem.
Legalization of Same-Sex Marriage in terms of Islamic Law: a Comparative Study of Indonesia and Germany
Authors: Nazar Muhamad , Sjaiful Muhammad , Zahrowati Zahrowati
Published: March 2024

Marriage is the behavior of creatures created by God Almighty so that life in the natural world develops well. Marriage is recommended and regulated in Islam because it has a noble purpose. As time progresses, marriages which were initially only carried out by heterosexual couples are now seeing the emergence of the phenomenon of same-sex marriages or marriages by LGBT people. What is worrying is that the LGBT phenomenon is growing rapidly in Indonesia due to increasingly open freedoms. This raises pros and cons. Same-sex marriage in Indonesia, a Muslim-majority country, has caused controversy and is considered illegal deviant behavior. However, there are also several countries in the world that have legalized same-sex marriage, including Germany, where Muslims are a minority. In 2017, Germany officially passed regulations regarding same-sex marriage including the right to adopt children. This research aims to conduct a comparative analysis of the topic of same-sex marriage among LGBT actors in Germany and Indonesia using a socio-legal approach. This research has the results of a study that the phenomenon of same-sex marriage by LGBT people that occurs in Germany and Indonesia are two different things and cannot be equated. Several factors behind this are the socio-cultural context which causes society's reactions and the implementation of government regulations regarding same-sex marriage to be different.
Fast Charge Algorithm Development for Battery Packs under Electrochemical and Thermal Constraints with JModelica.org
Authors: Romero Alberto , Angerer Johannes
Published: March 2024

Strict operating boundaries on commercial lithium ion cells are defined to mitigate the effect of aging (loss of capacity and increase in internal resistance), as well as avoiding safety hazards, like the appearance of lithium plating during charge, which can lead to internal short circuit and subsequent thermal runnaway. Therefore, to develop fast charge algorithms that maximize charging speeds, electrochemical and thermal constraints must be considered. Most studies so far have focused on the single cell problem, whereas pack-level fast charge challenge has been tackled directly by the industry. The reason is that the temperature difference between cells within a battery pack is often considered small, and therefore that optimal charging profiles can be extrapolated from single cell investigations. In practice, temperature spread can reach up to 10 K from coldest to warmest points in the pack, and at least 5 K between same position of different cells. With this in mind, a Nonlinear Model Predictive Control (NLMPC) scheme is proposed that considers both electrochemical and thermal constraints at pack level, establishing, at least on a theoretical basis, the practical limits of fast charge. We demonstrate how active thermal management, i.e., controlling the fluid inlet temperature, is critical to reducing charging times below 40 min (from 0% to 80% state of charge), and discuss some challenges when using online optimization-based control techniques
Introducing Dialectic Mechanics
Authors: Zimmer Dirk , Oldemeyer Carsten
Published: March 2024

This paper introduces a new method for mechanical systems with its own interface that enables the object-oriented formulation of very stiff contacts. It thereby suppresses high frequencies and yields stable replacement dynamics leading to an equivalent steady state. Potential applications are the efficient modeling and simulation of robotic manipulation or the easier handling of what formerly have been variable-structure systems.
HVAC and Control Templates for the Modelica Buildings Library
Authors: Gautier Antoine , Wetter Michael , Hu Jianjun , Tummescheit Hubertus
Published: March 2024

This article reports on our experience in creating Modelica models for systems with thousands of configurations and closed-loop controls. The development of such templates required exploration of class parameterization techniques and data structures for handling large sets of equipment parameters. By describing these issues and the approach taken, we show how the Modelica language can support advanced templating logic. The main limitation we encountered relates to parameter assignment and propagation. The interpretation of parameter attributes at user interface runtime, or the handling of non-trivial constructs involving record classes at compile time is not consistently supported by Modelica tools. This leads to choices that are difficult to make when looking for a generic implementation.
Accelerating the simulation of equation-based models by replacing non-linear algebraic loops with error-controlled machine learning surrogates
Authors: Heuermann Andreas , Hannebohm Philip , Schäfer Matthias , Bachmann Bernhard
Published: March 2024

When simulating a Modelica model, non-linear algebraic loops may be present, which involves solving multiple equations simultaneously. The classical Newton-Raphson method is commonly employed for solving a non-linear equation system (NLS). However, the computational burden of using this method during simulation can be significant. To tackle this issue, utilizing artificial neural networks (ANNs) to approximate the solution of algebraic loops is a promising approach. While ANN surrogates offer fast performance, ensuring the correctness of the computed solution or quantifying reliability can be challenging. This publication presents a prototype, based on the OpenModelica compiler (OMC), that automates the extraction of time-consuming algebraic loops. It generates training data, trains ANNs using machine learning (ML) methods, and replaces the algebraic loops with ANN surrogates in the simulation code. A hybrid approach, combining the trained surrogate with the nonlinear Newton solver, is then used to compute the solution with a desired level of accuracy.
Parameter Estimation of Modelica Building Models Using CasADi
Authors: Cañas Carlos Durán , Arroyo Javier , Gillis Joris , Helsen Lieve
Published: March 2024

Predictive control can substantially improve the energy performance of buildings during operation, but it requires a model of the building to be implemented. Gray-box model identification starts from a physics-based model (white-box element) and complements it with measurements from the operation of the building (black-box element). The level of detail of the original model is limited by the optimization problem that needs to be solved when estimating its parameters. Consequently, it is common to heavily simplify building models hindering the intelligibility of their parameters and limiting their application potential. This paper investigates the accuracy and scalability of different transcription methods for parameter estimation of building models. The methodology starts from a Modelica model as an initial guess which is transferred to CasADi using the Functional Mockup Interface to solve the parameter estimation problem. The study demonstrates the high effectiveness of multiple shooting. Single shooting and direct collocation could be more suitable for setups with faster integration times or with increased granularity in the training data, respectively.
Simulation Model as a Service (SMaaS): A concept for integrated deployment, execution and tracking of system simulation models
Authors: Stelzig Philipp Emanuel , Rodenberg Benjamin
Published: March 2024

System simulation is dealing with increasingly multiphysical and cyber-physical systems that involve multiple engineering domains. In development and production, system manufacturers often rely on supplier parts and their digital representations. To deal with this inherently collaborative setting in a more efficient way we propose a concept of Simulation Model as a Service (SMaaS) developed at simercator. In this article, we apply established workflows from software engineering to system simulation to create more efficient workflows, discuss the compliance with technical, economic, and regulatory requirements, and present a software for digital supply chain management that implements SMaaS.
Convection of Chemicals and Other Substances with ThermoSysPro
Authors: Simonini Giorgio , Duval Arnaud , Hocine-Rastic Sarah , Praud Mathilde
Published: March 2024

Digital twins are a powerful support tool for plant operation: they provide further understanding on ongoing phenomena and allow realistic projection of the current plant state into the future. Among other twins, EDF is developing a digital twin of the chemistry of the secondary circuits of its nuclear plants. Such a tool will give access to the pH in any point of the circuit and in any operating condition (e.g. partial load, power transients...), outperforming the current, limited, monitoring techniques. It is expected to help operators and engineers to better monitor the circuit (e.g. for erosion corrosion) and anticipate the consequences on equipment of different operating strategies (e.g. for amines’ injection pumps maintenance). ThermoSysPro, the EDF R&D’s thermal-hydraulic library, is the bedrock of the tool under development. To meet the needs of the target application, modeling of amines convection and some related chemistry, allowing the computation of pH, are introduced in a new version of the library. Moreover, the presented approach aims at proposing a general framework allowing the convection of custom substances (i.e. easily customized by the end user following its needs). This will open the door for a wide range of other applications: radioactive substances, pollution (e.g. salted water ingress coming from a heat-exchanger leak), just to cite a few, could be modeled in ThermoSysPro to augment the scope of the digital twins.
Secure Exchange of Black-Box Simulation Models using FMI in the Industrial Context
Authors: Wolf Christian , Schleipen Miriam , Frey Georg
Published: March 2024

FMI is a standard for exchanging simulation models in a platform-agnostic way, also in form of black-box models. In the industrial context, it is common to exchange such black-box simulation models especially between partners. Using and running such models, though, is a security issue as there is no way to verify and validate the content of the models. This security issue must be addressed especially in the industrial context where security is considered high priority in general. Based on an exemplary model exchange, possible attacks are analyzed in this work. By using cryptography, three different approaches to pack the additional metadata are presented that aim at providing end-to-end integrity checks to a black-box simulation models. Together with administrative measures, this allows to define those FMUs to be trusted and executed. For sake of completeness, a prototype was implemented to help with the cryptographic processes and show the effectiveness of the provided solution.
The Common Requirement Modeling Language
Authors: Bouskela Daniel , Buffoni Lena , Jardin Audrey , Molnair Vince , Pop Adrian , Zavada Armin
Published: March 2024

CRML (the Common Requirement Modeling Language) is a new language for the formal expression of requirements. The ambition is to release the language as an open standard integrated into the open source modeling and simulation tool OpenModelica and interoperable with the open systems engineering standard SysMLv2. CRML allows to express requirements as multidisciplinary spatiotemporal constraints that can be verified against system design by co-simulating requirements models with behavioral models. Particular attention is paid to the following aspects. The requirements models must be easily legible and sharable between disciplines and stakeholders and must capture realistic constraints on the system, including time-dependent constraints with probabilistic criteria, in recognition of the fact that no constraint can be fulfilled at any time at any cost. The theoretical foundation of the language lies on 4-valued Boolean algebra, set theory and function theory. The coupling of the requirements models to the behavioral models is obtained through the specification of bindings, the automatic generation of Modelica code from the CRML model and use of the FMI and SSP standards. CRML and the proposed methodology is compatible with SysMLv2, forming a comprehensive work-flow and tool-chain encompassing requirement analysis, system design and V&V. The final objective is to facilitate the demonstration of correctness of system behavior against assumptions and requirements by building a workflow around Model-Driven Engineering and Open Standards for automating the creation of verification simulators.
Steady State and Dynamic Simulation of a Small-Scale Hollow Fiber Membrane Humidifier
Authors: Pollak Markus , Kutz Manuel , Schulze Christian , Tegethoff Wilhelm , Köhler Jürgen
Published: March 2024

Membrane humidifiers are often used in mobile Proton Exchange Membrane (PEM) fuel cell systems to humidify the supply air of the fuel cell. The purpose of a humidifier in a PEM fuel cell system is to prevent a dry-out of the fuel cell membrane. In this paper, a humidifier model based on the number of transfer units (NTU) approach is set-up in Modelica, calibrated and validated using measurement of a test rig. In a first step, the model is evaluated for steady state operating conditions. Second the developed membrane humidifier model is simulated with dynamically changing operating conditions that are typical for mobile applications. Those simulation results are then compared to measurements. The aim of our study is to evaluate the accuracy of the NTU humidifier model under various operating scenarios. Our results indicate that the NTU model is suitable to predict the water transfer under steady state as well as dynamically changing operating conditions with low deviations to measurements.
Modeling Components of a Turbine-Generator System for Sub-Synchronous Oscillation Studies with Modelica
Authors: Segerstrom Eric , Vanfretti Luigi , Mishra Chetan , Jones Kevin D.
Published: March 2024

In power systems, subsynchronous oscillations associated with the interaction between a mechanical rotor shaft and electrical system can lead to equipment damage if improperly mitigated. This paper describes the development of a scalable, multi-mass torsional shaft model and a synchronous machine model with DC offset torque components included using Modelica. When coupled, these models can be used to perform shaft torsional studies. Two methods of coupling the shaft with the rest of the turbine-generator system are devised and analyzed. A single-machine, infinite-bus test system using the torsional shaft model and generator model developed in this paper is proposed to observe the penetration of subsynchronous oscillations throughout an electrical system. The test system is then modified to model subsynchronous resonance leading to system instability. Analysis of the models described in this paper highlights the value of the Modelica_LinearSystems2 library in determining the torsional mode shapes and frequencies associated with a turbine-generator system model.
Modeling Specialized Electric Power Generators, Excitation Systems and Prime Movers used by North American Utilities
Authors: Islam Shamimul , Laera Giuseppe , De Castro Fernandes Marcelo , Vanfretti Luigi , Mishra Chetan , Jones Kevin D.
Published: March 2024

The North American Electric Reliability Corporation (NERC) is expected to mandate model validation of power plant equipment in the near future. This will create a need to validate models for a large fleet of existing and future power plants. Historically, model validation of synchronous generators, excitation system, turbine governor, and other power system equipment has been conducted in diverse platforms. As a contribution to the power system model implementation using Modelica language and validation against commercial tools this work continues to develop power system component models and enriching the Open-Instance Power System Library (OpenIPSL). As a part of the development of OpenIPSL this paper describes the development of models used by North American utilities that follow NERC modeling requirements, including models of a synchronous generator, an excitation system, a turbine and governor using Modelica language in Dymola. The component implementation process is described and the validation of the models implemented in Modelica against PSS/E using both a single machine infinite bus (SMIB) and multi-machine system models is illustrated.
Numerically Efficient Degradation Model of Catalyst Layers in PEM Fuel Cells using Modelica
Authors: Trägner Jakob , Heinke Steffen , Tegethoff Wilhelm , Köhler Jürgen
Published: March 2024

Degradation of the catalyst layer is a major challenge for the commercialization of polymer electrolyte membrane fuel cells (PEMFCs). Numerical modeling helps to understand and analyse the degradation phenomena, to transfer results from accelerated stress tests (ASTs) to real applications and to optimize operating conditions regarding degradation. We implemented a typical catalyst degradation model for platinum used in literature in Modelica. A numerical analysis shows the problem of “stiffness” for these models, meaning the tremendous difference in time constants. Assuming the platinum ion concentration in the ionomer to be in quasi-equilibrium helps to reduce the “stiffness”, increases simulation speed and numerical robustness without any relevant inaccuracy. For a typical AST, the simulation speed can be more than doubled ending in a real-time factor of over 1,000. Thus, 500 hours of AST can be simulated within less than 30 minutes, which gives room for extensive analysis with the model.
Piecewise-Steady-State Modelica Simulations for the Conceptual Design Phase of Industrial Processes
Authors: Agner Raphael , Grand Jonas , Duss Andrin , Wellig Beat
Published: March 2024

The conceptual design of industrial processes is challenging as relatively little information about the eventually selected equipment and their operation is known in this early design stage. Furthermore, the systems are increasingly integrated with themselves, and their design must be addressed systematically. Simulation can assist in better understanding the effects of design decisions on the resulting system performance. To facilitate the simulation of industrial processes in this early design phase, this paper proposes an approach to modeling system components specifically aimed at employing known key design parameters and assuming steady-state behavior of the process for a certain period of time (e.g. one hour). A solution over a longer period of time (e.g. for a year) can then be obtained by simulating a multitude of such shorter periods, leading to the piecewise-steady-state solution. The proposed approach is developed with an exemplary case study, based on a real industrial site. The resulting model computes the annual load profile within the range of seconds for the given case study.
Coupling of Thermal and Electrical Systems for the Simulation of ECS Architectures
Authors: Ablanque Nicolás , Gurumurthy Sriram , Torras Santiago , Monti Antonello , Rigola Joaquim , Oliet Carles
Published: March 2024

This work is focused on the coupling of two complex models based on different underlying physics: a vapor compression refrigerating system and its electrical drive system. The main challenge was to correctly handle the large simulation time constant difference which is three orders of magnitude smaller for the electrical system. The two models have been originally developed following very specific requirements (i.e. high numerical robustness and low time consumption) for their suitable use in simulations of large and complex aircraft Environmental Control Systems (ECS). The direct coupling of both systems has been observed to cause numerical instabilities, therefore, a coupling approach based on non-invasive dynamic relaxations has been implemented. The resulting combined simulations have shown to be numerically stable for the complete range of operating conditions and for a wide range of time steps.
Distributed Parameter Pneumatics
Authors: Fischer Felix , Schmitz Katharina
Published: March 2024

Pneumatics is a branch of engineering that deals with the use of pressurized air or gases to create mechanical motion. It involves the study and application of systems and components such as air compressors, valves, cylinders, and actuators to control and transmit power through the use of compressed air. For highly dynamic events in pneumatic systems, such as fast switching processes in automation technology, lumped-parameter simulation is not sufficient to correctly calculate the pressure build-up in pipes. The propagation and reflections of different pressure waves and refraction waves cannot be accounted for by the zero-dimensional models provided by the Modelica.Fluid library. Therefore, a method for calculating such events using the finite volume method is presented in this paper. The library presented in this work, uses Gudonov's scheme and an arbitrary Riemann-solver and gas model to calculate the time evolution inside 1D or 2D discretized pneumatic components as well as systems composed of these components.
Hide ‘n seek: individual behavioural responses of cattle excreting different amounts of nematode eggs—potential threshold for pasture contamination assessment
Authors: Guzhva Oleksiy , Hessle Anna , Högberg Niclas , Lidfors Lena , Höglund Johan
Published: March 2024

The aim of this study was to investigate how the activity of cattle under natural grazing conditions is related to their individual parasite contribution (IPC). Potentially, the individuals contributing the most to the contamination of the pasture with gastrointestinal nematodes (GIN) could then be identified and selectively treated based on sensor data thresholds. A total of 58 steers of the dairy breeds Swedish Red (SR, n = 19) and Swedish Holstein (SH, n = 39) were used for sensor-based data collection that lasted for a total of 10 weeks from 4 May to 13 July 2022. All steers were inoculated with a priming dose of nematode larvae and weighed in conjunction with the pasture release. The animals were then divided into four experimental groups and treated with ivermectin (IVM PO, Boehringer Ingelheim, 0.5 mg/kg BW) at different intervals to obtain an exposure contrast (Group A was left untreated, Group B/IVM PO-4w was treated after 4 weeks, Group C/IVM PO-8w was treated after 8 weeks, and Group D/IVM PO-4&8w was treated after 4 weeks and then after 8 weeks). The steers were weighed on four further occasions, during which faecal samples were also taken for parasite testing. Activity data were collected using leg-mounted IceQube sensors and body weight data and faecal samples were collected bi-weekly. The new threshold metric (IPC) was proposed for individuals with different faecal egg count (FEC) levels [NO (no contribution) <20 EPG, LO (low contribution) = 20–150 EPG, ME (medium contribution) = 150–250 EPG, and HI (high contribution) ≥250 EPG] The effects of IPC on activity patterns were analysed stepwise using a Generalised Estimating Equations model implemented in Python programming language. Results showed significant effects of different IPC values on motion index and number of steps taken (adjusted p-value of 0.008, 0.018, 0.041, and 0.001 for individuals with NO, LO, ME, and HI IPC values, respectively). There were some breed effects on the average number of steps and minutes spent lying. The results also provide alternative threshold methods aimed at finding more sustainable ways of using anthelmintics and integrating individual data into future parasite control strategies.