bluuebunny/crossref_metadata_2025 huggingface dataset:
Sparse Polynomial Chaos Expansion for Uncertainty Quantification of Composite Cylindrical Shell with Geometrical and Material Uncertainty
Authors: Chen Ming , Zhang Xinhu , Shen Kechun , Pan Guang
Published: May 2022

The geometrical dimensions and mechanical properties of composite materials exhibit inherent variation and uncertainty in practical engineering. Uncertainties in geometrical dimensions and mechanical properties propagate to the structural performance of composite cylindrical shells under hydrostatic pressure. However, traditional methods for quantification of uncertainty, such as Monte Carlo simulation and the response surface method, are either time consuming with low convergence rates or unable to deal with high-dimensional problems. In this study, the quantification of the high-dimensional uncertainty of the critical buckling pressure of a composite cylindrical shell with geometrical and material uncertainties was investigated by means of sparse polynomial chaos expansion (PCE). With limited design samples, sparse PCE was built and validated for predictive accuracy. Statistical moments (mean and standard deviation) and global sensitivity analysis results were obtained based on the sparse PCE. The mean and standard deviation of critical buckling pressure were 3.5777 MPa and 0.3149 MPa, with a coefficient of variation of 8.801%. Global sensitivity analysis results from Sobol’ indices and the Morris method showed that the uncertainty of longitudinal modulus has a massive influence on the critical buckling pressure of composite cylindrical shell, whereas the uncertainties of transverse modulus, shear modulus, and Poisson’s ratio have a weak influence. When the coefficient of variation of ply thickness and orientation angle does not surpass 2%, the uncertainties of ply thickness and orientation angle have a weak influence on the critical buckling pressure. The study shows that the sparse PCE is effective at resolving the problem of high-dimensional uncertainty quantification of composite cylindrical shell with geometrical and material uncertainty.
Experimental and Numerical Study on the Hydraulic Characteristics of an S-Type Bidirectional Shaft Tubular Pump
Authors: Chen Jiaqi , Mao Jieyun , Shi Hongbo , Wang Xikun
Published: May 2022

In order to study the characteristics of a bidirectional shaft tubular pump with S-type symmetric airfoil blades, a prototype model was designed, manufactured, and tested. The energy characteristics, cavitation characteristics, and runaway characteristics of the pump were obtained under forward and reverse operating conditions for five different blade angles. Based on the basic equations of the pump and the inlet and outlet velocity triangles, combined with model tests and numerical simulations, the hydraulic performance of the pump was extensively analyzed and evaluated. In addition, semi-empirical equations for reverse efficiency and runaway characteristics were proposed. The dynamic pressure-drop coefficients were introduced to compare the cavitation performance under different flow rates in forward and reverse operations. The results reveal that the efficiency of the pump in reverse operation is greater than that of forward operation only under a very small flow rate. While the cavitation performance of the bidirectional pump in the two operating modes is almost the same, the runaway speed and backflow rate in forward operation are considerably greater than those of reverse operation. The results provide an important reference for the safe and stable operation of bidirectional shaft tubular pumps.
Characteristics of Chromophoric Dissolved Organic Matter (CDOM) Produced by Heterotrophic Bacteria Isolated from Aquaculture Systems
Authors: Gullian-Klanian Mariel , Gold-Bouchot Gerardo , Sánchez-Solís María José
Published: May 2022

Heterotrophic bacteria (HB) play an important role in aquatic ecosystems as recyclers of dissolved organic matter (DOM). The objective of this study was to characterize the spectral characteristics of intracellular (IC), and extracellular (EC) compounds produced by 12 HB isolated from two aquaculture systems. Microorganisms belonging to the genera Bacillus, Paenibacillus, and Psychrobacillus were identified by analysis of the 16S ribosomal gene. Aliquots of bacterial culture were centrifugated every hour (1st to 7th) to obtain the EC compounds. The pellet was ultrasound-lysed to obtain the IC compounds. Excitation-emission matrices were used in combination with parallel factor analysis (PARAFAC) to characterize the fluorescent components of DOM (FDOM). PARAFAC indicated two protein-like components and two humic-like components in both cell spaces. At the IC, B. macquariensis showed a high fluorescence index (FI), probably associated with fulvic acid, quinones, or ketones. Psychrobacillus insolitus showed an inverse correlation between spectral slopes S275–295 and S350–400 in the EC and IC fractions, which may indicate differential release of low and high molecular weight molecules in these two fractions. The opposite occurred with B. licheniformis and P. alvei. The origin of FDOM in HB is an important finding of this work. The most significant amount of protein-like substances was produced at the IC level, with the humic- and fulvic-type at the EC. The main finding of this work is the evidence of differential production of humic-type or protein-type FDOM production by HB species from marine and freshwater aquaculture systems in their intracellular and extracellular fractions, as well different relative molecular weight. For aquaculture, these findings suggest that some bacterial species show promise in supplying essential amino acids to growing organisms, and others play a major role in nutrient exchange and the global carbon cycle.
Low Oxygen Saturation of COVID-19 in Patient Case Fatalities, Limpopo Province, South Africa
Authors: Mphekgwana Peter M. , Sono-Setati Musa E. , Maluleke Abdul F. , Matlala Sogo F.
Published: May 2022

On 1 August 2020, South Africa’s Minister of Health announced that more than half of a million coronavirus cases were confirmed in the country. South Africa was by far the hardest-hit country in Africa, accounting for half of all infections reported across the continent. The prevalence of underlying conditions such as fever and blood oxygen saturation (SpO2) has been known known to be a significant determinant in the hospitalisation of COVID-19 patients. Low oxygen saturation on admission was reported as a strong predictor of in-hospital mortality in COVID-19 patients. The study sought to assess the association between body temperature and other clinical risk factors with low SpO2 among COVID-19 inpatient case fatalities. A quantitative retrospective study was carried out in Limpopo Province, employing secondary data from the Limpopo Department of Health (LDoH) on COVID-19 inpatients case fatalities across all districts in the province. The chi-square test and Pearson’s correlation coefficient were used to assess the relationship between body temperature and clinical risk factors with SpO2 levels. The findings of this paper indicated that age (older age), chills, sore throat, anosmia, dysgeusia, myalgia/body aches, diarrhoea and HIV/AIDS were associated with low SpO2 in-hospital mortality in COVID-19 patients. Nasal prongs and a face mask with a reservoir for respiratory support cannula were commonly used patient interfaces to provide supplemental oxygen, with the use of only a high-flow nasal cannula (HFNC) being minimal (7%). The majority of COVID-19 inpatient fatalities had normal body temperature (<38 °C) and SpO2, with no correlation between the two variables. Considering temperature screening as a possible strategy to combat the spread of COVID-19 or suspicious COVID-19 cases appeared, then, to be a pointless exercise. This study aimed to recommend new clinical criteria for detecting COVID-19 cases.
Application of Patient-Derived Cancer Organoids to Personalized Medicine
Authors: Shiihara Masahiro , Furukawa Toru
Published: May 2022

Cell models are indispensable for the research and development of cancer therapies. Cancer medications have evolved with the establishment of various cell models. Patient-derived cell lines are very useful for identifying characteristic phenotypes and susceptibilities to anticancer drugs as well as molecularly targeted therapies for tumors. However, conventional 2-dimensional (2D) cell cultures have several drawbacks in terms of engraftment rate and phenotypic changes during culture. The organoid is a recently developed in vitro model with cultured cells that form a three-dimensional structure in the extracellular matrix. Organoids have the capacity to self-renew and can organize themselves to resemble the original organ or tumor in terms of both structure and function. Patient-derived cancer organoids are more suitable for the investigation of cancer biology and clinical medicine than conventional 2D cell lines or patient-derived xenografts. With recent advances in genetic analysis technology, the genetic information of various tumors has been clarified, and personalized medicine based on genetic information has become clinically available. Here, we have reviewed the recent advances in the development and application of patient-derived cancer organoids in cancer biology studies and personalized medicine. We have focused on the potential of organoids as a platform for the identification and development of novel targeted medicines for pancreatobiliary cancer, which is the most intractable cancer.
Enhanced Risk of Osteoporotic Fracture in Patients with Sarcopenia: A National Population-Based Study in Taiwan
Authors: Zhang Han-Wei , Tsai Zhi-Ren , Chen Ko-Ta , Hsu Sheng-Lun , Kuo Yi-Jie , Lin Ying-Chin , Huang Shu-Wei , Chen Yu-Pin , Peng Hsiao-Ching , Tsai Jeffrey , Hsu Chung
Published: May 2022

Sarcopenia is a progressive and generalized skeletal muscle disorder associated with poor health outcomes in older adults. However, its association with the risk of fracture risk is yet to be clarified. Therefore, this study aimed to assess the incidence and consequence of osteoporosis-related fractures among patients with sarcopenia in Taiwan. A retrospective, population-based study on 616 patients with sarcopenia, aged >40 years, and 1232 individuals without sarcopenia was conducted to evaluate claims data from Taiwan’s National Health Insurance Research Database collected in the period January 2000–December 2013. The incidence rate of osteoporosis-related fracture was 18.13 and 14.61 per 1000 person years in the patients with sarcopenia and comparison cohort, respectively. Patients with sarcopenia had a greater osteoporotic fracture risk (adjusted hazard ratio [HR] 2.11; 95% confidence interval [CI] 1.47–3.04) after correcting for possible confounding. Additionally, females showed statistically significant correlations of sarcopenia with osteoporosis-related fracture risk (HR 1.53; CI 0.83–2.8 for males and HR 2.40, CI 1.51–3.81 for females). During this retrospective study on the fracture risk in Taiwan, an adverse impact of sarcopenia was observed, which substantiates the need to work toward sarcopenia prevention and interventions to reverse fracture susceptibility in patients with sarcopenia.
Adult Stem Cells in Aging
Authors: Trivanović Drenka
Published: May 2022

Aging process is associated with numerous intrinsic and extrinsic factors that contribute to the adipose tissue accumulation, atherosclerosis, immune system failures, bone fragility, and cancer [...]
Physiologically-Based Pharmacokinetics Modeling for Hydroxychloroquine as a Treatment for Malaria and Optimized Dosing Regimens for Different Populations
Authors: Zhai Jingchen , Ji Beihong , Cai Lianjin , Liu Shuhan , Sun Yuchen , Wang Junmei
Published: May 2022

Malaria is a severe parasite infectious disease with high fatality. As one of the approved treatments of this disease, hydroxychloroquine (HCQ) lacks clinical administration guidelines for patients with special health conditions and co-morbidities. This may result in improper dosing for different populations and lead them to suffer from severe side effects. One of the most important toxicities of HCQ overdose is cardiotoxicity. In this study, we built and validated a physiologically based pharmacokinetic modeling (PBPK) model for HCQ. With the full-PBPK model, we predicted the pharmacokinetic (PK) profile for malaria patients without other co-morbidities under the HCQ dosing regimen suggested by Food and Drug Administration (FDA) guidance. The PK profiles for different special populations were also predicted and compared to the normal population. Moreover, we proposed a series of adjusted dosing regimens for different populations with special health conditions and predicted the concentration-time (C-T) curve of the drug plasma concentration in these populations which include the pregnant population, elderly population, RA patients, and renal impairment populations. The recommended special population-dependent dosage regimens can maintain the similar drug levels observed in the virtual healthy population under the original dosing regimen provided by FDA. Last, we developed mathematic formulas for predicting dosage based on a patient’s body measurements and two indexes of renal function (glomerular filtration rate and serum creatine level) for the pediatric and morbidly obese populations. Those formulas can facilitate personalized treatment of this disease. We hope to provide some advice to clinical practice when taking HCQ as a treatment for malaria patients with special health conditions or co-morbidities so that they will not suffer from severe side effects due to higher drug plasma concentration, especially cardiotoxicity.
Social Media and Chronic Pain: What Do Patients Discuss?
Authors: Goudman Lisa , De Smedt Ann , Moens Maarten
Published: May 2022

A high number of online support groups have been created on social media platforms to reinforce personal empowerment and social support. The goal of this study was to perform natural language processing by constructing a bag-of-words model and conducting topic modelling based on posts extracted from a chronic pain community. The subreddit called ‘r/sChronicPain’ was used to investigate communication on social media platforms for chronic pain patients. After data cleaning and lemmatisation, a word cloud was constructed, and the most frequent words and most frequent body regions were counted. Latent Dirichlet allocation was used to perform topic modelling. In the final analysis set, 937 unique posts were included. The most frequent word was ‘pain’, followed by ‘doctor’, ‘day’, ‘feel’, ‘back’, ‘year’, and ‘time’. Concerning the body regions, ‘back’ was most often mentioned, followed by ‘neck’ and ‘leg’. Based on coherence scores, one topic was extracted with ‘pain’ as the keyword with the highest weight. In line with the allocation of chronic low-back pain as a major health problem and increasing prevalence, back pain was most often mentioned. It seems that the primarily treatment trajectories that are proposed by medical physicians are discussed on social media, compared to interventions by other healthcare providers.
A Search Methodology Based on Industrial Ontology and Machine Learning to Analyze Georeferenced Italian Districts
Authors: Massaro Alessandro , Cosoli Gabriele , Magaletti Nicola , Costantiello Alberto
Published: May 2022

The subject of the proposed study is a method implementable for a search engine able to provide supply chain information, gaining the company’s knowledge base. The method is based on the construction of specific supply chain ontologies to enrich Machine Learning (ML) algorithm results able to filter and refine the searching process. The search engine is structured into two main search levels. The first one provides a preliminary filter of supply chain attributes based on the hierarchical clustering approach. The second one improves and refines the research by means of an ML classification and web scraping. The goal of the searching method is to identify a georeferenced supply chain district, finalized to optimize production and planning production strategies. Different technologies are proposed as candidates for the implementation of each part of the search engine. A preliminary prototype with limited functions is realized by means of Graphical User Interfaces (GUIs). Finally, a case study of the ice cream supply chain is discussed to explain how the proposed method can be applied to construct a basic ontology model. The results are performed within the framework of the project “Smart District 4.0”.
Challenges and Innovations of Real Estate for Achieving Spatial Balance in Post-Disaster Countries
Authors: Azzam Mounir , Graw Valerie , Rienow Andreas
Published: May 2022

While real estate is a significant pillar of stability among communities, it can also be the most vulnerable to disasters triggered by natural or man-made hazards, which cause the spatial dimension of metropolitan areas to be disturbed due to critical variables, such as land loss, societal collapse, and changes in population distribution resulting from refugee movements, which, in turn, affect properties, causing a fluctuation in terms of equality. In this regard, the precise monitoring of spatial imbalance is an eminent instrument for achieving socio-spatial sustainability via recovery strategies. This paper provides a systematic review of 96 studies in order to analyze the spatial challenges and innovations of real estate in the aftermath of disasters with realistic projections on five case studies—from Haiti, Nigeria, Rwanda, Ethiopia, and the United States of America—varying according to the type, size, and impact of the disaster, and real estate administrative arrangements. Through the review, the challenges embodied by the legal deficit and the multiplicity of real estate tenure systems in addition to the discrimination of access rights to real estate and the insecurity of property and, subsequently, forced migration movements are highlighted. The impacts of the COVID-19 pandemic on the spatial balance of real estate have been examined. Finally, real estate innovations are reviewed to investigate the extent to which real estate can promote the spatial balance of disaster-prone nations.
Stakeholders’ Perspective on Groundwater Management in Four Water-Stressed Mediterranean Areas: Priorities and Challenges
Authors: Bonì Roberta , Teatini Pietro , Zoccarato Claudia , Guardiola-Albert Carolina , Ezquerro Pablo , Bru Guadalupe , Tomás Roberto , Valdes-Abellan Javier , Pla Conception , Navarro-Hernández María I. , Elçi Alper , Çaylak Baris , Ören Ali Hakan , Shatanawi Khaldoun , Mohammad Alsharifa Hind , Abu Hajar Husam , Letterio Tommaso , Genovesi Roberto , Hreisha Hazem , Al-Mimi Qamar , Meisina Claudia
Published: May 2022

Recent studies highlight the fragility of the Mediterranean basin against climate stresses and the difficulties of managing the sustainable development of groundwater resources. In this work, the main issues related to groundwater management have been identified from the stakeholder’s perspective in the following four representative water-stressed Mediterranean areas: the coastal aquifer of Comacchio (Italy), the Alto Guadalentín aquifer (Spain), the alluvial aquifer of the Gediz River basin (Turkey), and the Azraq aquifer (Azraq Wetland Reserve, Jordan). This has been achieved by designing a methodology to involve and engage a representative set of stakeholders, including a questionnaire to learn their point of view concerning the current management of aquifer systems and their experience with the already available tools for groundwater resource management, such as monitoring networks and numerical models. The outcome of the survey has allowed us to identify both particular and common challenges among the four study sites and among the various groups of stakeholders. This information provides valuable insights to improve the transfer of scientific knowledge from the research centers to the authorities managing the groundwater resources and it will help to plan more effective research activities on aquifer management. The proposed methodology could be applied in other aquifers facing similar problems.
Estimating Road Mortality Hotspots While Accounting for Imperfect Detection: A Case Study with Amphibians and Reptiles
Authors: Hallisey Noah , Buchanan Scott W. , Gerber Brian D. , Corcoran Liam S. , Karraker Nancy E.
Published: May 2022

Wildlife road mortality tends to aggregate spatially at locations commonly referred to as road mortality hotspots. Predictive models can be used to identify locations appropriate for mitigation measures that reduce road mortality. However, the influence of imperfect detection (e.g., false absences) during road mortality surveys can lead to inaccurate or imprecise spatial patterns of road mortality hotspots and suboptimal implementation of mitigation measures. In this research, we used amphibians and reptiles as a case study to address imperfect detection issues when estimating the probability of road mortality hotspots using occupancy detection modeling. In addition, we determined the survey effort needed to achieve a high probability of detecting large roadkill events. We also assessed whether vehicle travel reductions associated with the COVID-19 pandemic travel restrictions led to reductions in road mortality. We conducted surveys at 48 sites throughout Rhode Island, USA, from 2019–2021. In total, we observed 657 carcasses representing 19 of Rhode Island’s 37 native species. Of the 19 native species, eight species of frogs, four species of salamanders, four species of snakes, and three species of turtles were observed. We documented a reduction in roadkill density and the proportion of dead versus live amphibians and reptiles in pandemic years (2020 and 2021), but we were unable to link reductions in roadkill density to reductions in traffic volume. Our model results indicated that large roadkill events were more likely to occur on roads near wetlands and with low traffic volume and were more likely to be detected as daily precipitation increased. We determined that there was a low probability of detecting large roadkill events, suggesting that imperfect detection influences detection of large roadkill events, and many were likely missed during our surveys. Therefore, we recommend using occupancy modeling to account for the influence of imperfect detection when estimating road mortality hotspots. This approach will more effectively guide the implementation of mitigation measures.
Antimicrobial Properties of Compounds Isolated from Syzygium malaccense (L.) Merr. and L.M. Perry and Medicinal Plants Used in French Polynesia
Authors: Quenon Camille , Hennebelle Thierry , Butaud Jean-François , Ho Raimana , Samaillie Jennifer , Neut Christel , Lehartel Tamatoa , Rivière Céline , Siah Ali , Bonneau Natacha , Sahpaz Sevser , Anthérieu Sébastien , Lebegue Nicolas , Raharivelomanana Phila , Roumy Vincent
Published: May 2022

A preliminary ethnopharmacological survey, achieved in French Polynesia, led to the collection of the most cited plants among 63 species used to treat “infectious” diseases, with a description of their medicinal uses. Bibliographical investigations and antimicrobial screening permitted the selection of the botanical species Syzygium malaccense (Myrtaceae) for phytochemical analysis. Leaves of Syzygium malaccense were usually used in mixture with rhizomes of Curcuma longa to treat infectious diseases such as cystitis. The methanolic plant extracts were tested in vitro with an agar microdilution method on 33 bacteria strains and 1 yeast to obtain their Minimal Inhibitory Concentration (MIC), and cytotoxicity against HepG2 cells were evaluated. Antimicrobial synergistic effects of methanolic plant extracts from leaves of Syzygium malaccense and rhizomes from Curcuma longa were also evaluated. The bio-guided isolation of leaf extract from Syzygium malaccense led to the identification of seven alkyl-salicylic acids (anacardic acids or ginkgolic acids C15:0, C15:1, C17:0, C17:1, C17:2, C17:3 and C19:1) described for the first time in this species. All compounds were tested against Staphylococcus aureus (18.75 < MIC < 75.0 µg/mL), Streptococcus pyogenes (2.34 < MIC < 18.75 µg/mL) and Pseudomonas aeruginosa (MIC = 150 µg/mL), and their structure–activity relationships were discussed. The methanolic extract and salicylic derivatives from S. malaccense showed an interesting antimicrobial activity against Gram+ bacteria, without toxicity on hepG2 cells at 400 μg/mL. Moreover, these antibacterial compounds have already been studied for their anti-inflammatory activity, which supports the therapeutic interest of S. malaccense against infectious diseases.
Atherosclerosis and Its Impact on the Outcomes of Patients with Deep Venous Thrombosis
Authors: Keller Karsten , Prochaska Jürgen H. , Coldewey Meike , Göbel Sebastian , Schmitt Volker H. , Hahad Omar , Ullmann Alexander , Nagler Markus , Lamparter Heidrun , Espinola-Klein Christine , Münzel Thomas , Wild Philipp S.
Published: May 2022

Introduction: Atherosclerosis and pulmonary embolism (PE) affect cardiovascular mortality substantially. We aimed to investigate the impact of atherosclerosis on the outcomes of patients with deep venous thrombosis (DVT) and to identify the differences in DVT patients with and without PE. Methods: Patients with DVT with and without symptomatic atherosclerosis (defined as coronary artery disease, myocardial infarction and/or peripheral artery disease) as well as with and without PE under oral anticoagulation were enrolled during January 2011–April 2013 and compared. The impact of symptomatic atherosclerosis on several outcomes was analyzed. Results: Overall, 509 DVT patients (70.0 [56.0–77.0] years, 51.9% females) were included in this study. Among them, 179 (36.3%) had symptomatic atherosclerosis and 204 (40.1%) a concomitant PE. DVT patients with symptomatic atherosclerosis were older (74.0 [IQR 65.0–80.0] vs. 63.0 [48.0–75.0] years, p < 0.0001), more often male (56.4% vs. 43.9%, p = 0.0087) and had a higher prevalence of classical CVRF and a higher Charlson comorbidity index (7.00 [5.00–8.00] vs. 4.00 [2.00–6.00], p < 0.001). Symptomatic atherosclerosis was associated with increased mortality (HR 1.98 [95%CI 1.12–3.49], p = 0.018) and hospitalizations (HR 1.64 [95%CI 1.21–2.21], p = 0.0012) and primary long-term outcome (HR 1.99 [95%CI 1.31–3.04], p = 0.0013) during the 2 years follow-up-period in DVT patients. DVT patients without PE had diabetes mellitus (28.2% vs. 16.3%, p < 0.01) and symptomatic atherosclerosis (42.9% vs. 26.4%, p < 0.001) more often compared to DVT patients with PE, and symptomatic atherosclerosis was associated with isolated DVT (without PE) (OR 2.01 [95%CI 1.28–3.16], p < 0.01). Conclusions: Atherosclerosis was associated with isolated DVT (without PE) and increased mortality in DVT patients under oral anticoagulation. The profile of CVRF and comorbidities differed between DVT patients with and without a concomitant PE. In the case of DVT or PE, patients should be screened for concomitant atherosclerotic disease. Clinical Trial Registration: at clinicaltrials with Unique identifier NCT01809015.
Assessment of the Tribological Properties of the Steel/Polymer/Steel Sandwich Material LITECOR
Authors: Trzepieciński Tomasz , Kubit Andrzej , Slota Ján
Published: May 2022

The article presents the results of tribological investigations into the steel/polymer/steel sandwich material LITECOR® developed by ThyssenKrupp Steel Europe for applications in the automotive industry. Friction tests were carried out by means of a strip drawing test with the use of a special tribotester mounted on a uniaxial tensile test machine. The influence of sheet deformation on the value of the coefficient of friction (COF) was considered. For this purpose, the samples were subjected to a pre-deformation of 4%, 8% and 12%. Friction tests were carried out with different force values and under different friction conditions, i.e., in dry friction conditions and lubrication of the sheet surface with L-AN 46 machine oil. The highest values of COF were observed for as-received sheets. In contrast, apart from the friction process under the conditions of the lowest force analysed, the lowest value of the COF was observed for pre-strained sheets with a deformation of 12%. The lubrication efficiency of the pre-strained strip specimens with ε = 4% was between 10.5% and 16.3%, with a trend of increasing lubrication efficiency with increasing force. For pre-strained sheets with deformation ε = 12%, there was a trend of decreasing effectiveness from 14.9% to 9.03% with an increase in force.
Compressive Strength Evaluation of Ultra-High-Strength Concrete by Machine Learning
Authors: Shen Zhongjie , Deifalla Ahmed Farouk , Kamiński Paweł , Dyczko Artur
Published: May 2022

In civil engineering, ultra-high-strength concrete (UHSC) is a useful and efficient building material. To save money and time in the construction sector, soft computing approaches have been used to estimate concrete properties. As a result, the current work used sophisticated soft computing techniques to estimate the compressive strength of UHSC. In this study, XGBoost, AdaBoost, and Bagging were the employed soft computing techniques. The variables taken into account included cement content, fly ash, silica fume and silicate content, sand and water content, superplasticizer content, steel fiber, steel fiber aspect ratio, and curing time. The algorithm performance was evaluated using statistical metrics, such as the mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R2). The model’s performance was then evaluated statistically. The XGBoost soft computing technique, with a higher R2 (0.90) and low errors, was more accurate than the other algorithms, which had a lower R2. The compressive strength of UHSC can be predicted using the XGBoost soft computing technique. The SHapley Additive exPlanations (SHAP) analysis showed that curing time had the highest positive influence on UHSC compressive strength. Thus, scholars will be able to quickly and effectively determine the compressive strength of UHSC using this study’s findings.
Influence of Pulse–Pause Sequences on the Self-Heating Behavior in Continuous Carbon Fiber-Reinforced Composites under Ultrasonic Cyclic Three-Point Bending Loads
Authors: Premanand Aravind , Balle Frank
Published: May 2022

Several studies have been conducted in the Very High Cycle Fatigue (VHCF) regime on Carbon Fiber Reinforced Polymers (CFRP) in search of their fatigue limit beyond their typical service life, which is itself in the order of 108 loading cycles. The ultrasonic fatigue test (UFT) method has been recently gaining attention for conducting fatigue experiments up to 109 loading cycles. This can be attributed to the reduction of testing time, as the testing facility operates at a cyclic frequency of 20 kHz. The fatigue loading in UFT is usually performed in a pulse–pause sequence to avoid specimen heating and undesirable thermal effects. For this study, the pulse–pause combination of the UFT methodology was explored and its influence on the self-heating behavior of the CFRP material was analyzed. This was realized by monitoring the temperature evolution in the CFRP specimens at different pulse–pause combinations and correlating it with their final damage morphologies. From the obtained results, it is concluded that the specimen heating phenomenon depends on several variables such as cyclic loading amplitude, the pulse–pause combination, and the damage state of the material. Finally, it is proposed that the test procedure, as well as the testing time, can be further optimized by designing the experiments based on the self-heating characteristic of the composite and the glass transition temperature (Tg) of the polymer matrix.
Investigations on the Performance of Shotcrete Using Artificial Lightweight Shale Ceramsite as Coarse Aggregate
Authors: Hou Shengjun , Li Fuhai , Tang Huiqi , Wen Tao , Chen Zhao , Gao Hao
Published: May 2022

In this study, a type of artificial lightweight shale ceramsite (ALSC) was used as the coarse lightweight aggregate for shotcrete (LAS), of which the mechanical properties, chloride penetration ion resistance, and rebound behavior were investigated. Based on the experimental results on compressive, tensile, and bond strength, LAS meet the strength requirements, and the replacement rate of fly ash (FA) and silica fume (SF) are suggested to be kept at ~15% and 10%, respectively, to result in the best mechanical properties of LAS. Adding FA and SF to the mixture significantly improved the chloride ion penetration resistance (CPR) of LAS because of morphology effects and secondary hydration of FA and SF that lead to a denser microstructure of the mixture. The electric flux and chloride ion migration coefficient (DRCM) of LAS decreased by 56% and 67%, respectively, with FA increasing from 0 to 10%. The electric flux and DRCM further decreased by 71% (153C) and 66% (3.24 m2/s), respectively, with FA increasing from 10 to 20%. As 5–10% SF was further added, the electric flux and DRCM of LAS decreased to extremely low levels; for instance, with FA = 10% and SF = 10%, DRCM = 1.61 m2/s, and the electric flux was too small and could be ignored. The contact stresses between aggregate and shotcrete mixtures were measured to investigate the rebound trend of ALSC in shotcrete. According to the analyses of the theoretical model of the rebound behavior of aggregate in shotcrete proposed by Armelin and Banthia, because of the reduced contact stresses between ALSC and mortar and the smaller density of LAS compared with normal-weight aggregate, the rebound rate of ALSC was about half of that of normal-weight aggregate in the shooting process of the shotcrete.
Spectral and Angular Characteristics of the High-Contrast Dielectric Grating under the Resonant Interaction of a Plane Wave and a Gaussian Beam
Authors: Bellucci Stefano , Fitio Volodymyr , Smirnova Tatiana , Yaremchuk Iryna , Vernyhor Oleksandr , Bobitski Yaroslav
Published: May 2022

The resonant interaction of a plane wave and a one-dimensional Gaussian beam with a high-contrast dielectric grating was analyzed. Rigorous coupled wave analysis (RCWA) was used to numerically model the diffraction of a plane wave by the grating. RCWA, a discrete Fourier transform at the fulfillment (of the conditions) of the sampling theorem, was used to study diffraction of the Gaussian beam. The grating can be considered as a one-dimensional photonic crystal along which the waveguide mode propagates under resonance. The corresponding photonic crystal has both allowed and forbidden photonic bands for the propagating waveguide mode under resonance due to the high-contrast dielectric permittivity. There is no significant difference between the spectral and angular characteristics under the interaction of the plane wave or the Gaussian beam with grating, if the waveguide mode is in the forbidden photonic bandgap. The reflection coefficient from the grating is practically equal to unity for both cases. Resonant spectral and angular characteristics become wider at the Gaussian beam diffraction compared to the resonance curves for the plane wave in the case when the waveguide mode is in the allowed photon bandgap. The reflection coefficient from the grating becomes less than unity and its value tends to unity when the Gaussian beam width increases.
Scalable MXene and PEDOT-CNT Nanocoatings for Fibre-Reinforced Composite De-Icing
Authors: Monastyreckis Gediminas , Siles Juan Tortosa , Knotek Petr , Omastova Maria , Aniskevich Andrey , Zeleniakiene Daiva
Published: May 2022

In this study, the de-icing performance is investigated between traditional carbon fibre-based coatings and novel MXene and poly(3,4-ethylenedioxythiophene)-coated single-walled carbon nanotube (PEDOT-CNT) nanocoatings, based on simple and scalable coating application. The thickness and morphology of the coatings are investigated using atomic force microscopy and scanning electron microscopy. Adhesion strength, as well as electrical properties, are evaluated on rough and glossy surfaces of the composite. The flexibility and electrical sensitivity of the coatings are studied under three-point bending. Additionally, the influence of ambient temperature on coating’s electrical resistance is investigated. Finally, thermal imaging and Joule heating are analysed with high-accuracy infrared cameras. Under the same power density, the increase in average temperature is 84% higher for MXenes and 117% for PEDOT-CNT, when compared with fibre-based coatings. Furthermore, both nanocoatings result in up to three times faster de-icing. These easily processable nanocoatings offer fast and efficient de-icing for large composite structures such as wind turbine blades without adding any significant weight.
Polymerization Initiated by Graphite Intercalation Compounds Revisited: One-Pot Synthesis of Amphiphilic Pentablock Copolymers
Authors: Vladimirov Nikolay G. , Gitsov Ivan
Published: May 2022

This study reports the first attempt to employ a potassium–graphite intercalation compound (KC24) as an initiator for the one-pot synthesis of a multi-block copolymer. The results obtained show that KC24 successfully initiated the copolymerization, leading to a copolymer consisting of poly(styrene), poly(methyl methacrylate) and poly(ethylene oxide) blocks. When all three comonomers were introduced simultaneously or in a specific sequence, the resulting copolymers had molecular masses in the range between 170,000 Da and 280,000 Da. Their composition was investigated by size-exclusion chromatography with triple detection (dRI/UV/IR) and 1H-NMR. The analyses indicated that all copolymers were enriched in methyl methacrylate (50–66 mol%) despite the fact that the comonomers were added in equimolar amounts. Due to the layered structure of the initiator, the polymerization took place in the graphite interlayer spaces and lead to extensive delamination, indicating at the potential to produce in situ graphite/copolymer composite materials.
On Restricted Cohomology of Modular Classical Lie Algebras and Their Applications
Authors: Ibraev Sherali S. , Kainbaeva Larissa S. , Seitmuratov Angisin Z.
Published: May 2022

In this paper, we study the restricted cohomology of Lie algebras of semisimple and simply connected algebraic groups in positive characteristics with coefficients in simple restricted modules and their applications in studying the connections between these cohomology with the corresponding ordinary cohomology and cohomology of algebraic groups. Let G be a semisimple and simply connected algebraic group G over an algebraically closed field of characteristic p>h, where h is a Coxeter number. Denote the first Frobenius kernel and Lie algebra of G by G1 and g, respectively. First, we calculate the restricted cohomology of g with coefficients in simple modules for two families of restricted simple modules. Since in the restricted region the restricted cohomology of g is equivalent to the corresponding cohomology of G1, we describe them as the cohomology of G1 in terms of the cohomology for G1 with coefficients in dual Weyl modules. Then, we give a necessary and sufficient condition for the isomorphisms Hn(G1,V)≅Hn(G,V) and Hn(g,V)≅Hn(G,V), and a necessary condition for the isomorphism Hn(g,V)≅Hn(G1,V), where V is a simple module with highest restricted weight. Using these results, we obtain all non-trivial isomorphisms between the cohomology of G, G1, and g with coefficients in the considered simple modules.
On a System of ψ-Caputo Hybrid Fractional Differential Equations with Dirichlet Boundary Conditions
Authors: Awadalla Muath , Abuasbeh Kinda , Subramanian Muthaiah , Manigandan Murugesan
Published: May 2022

In this article, we investigate sufficient conditions for the existence and stability of solutions to a coupled system of ψ-Caputo hybrid fractional derivatives of order 1<υ≤2 subjected to Dirichlet boundary conditions. We discuss the existence and uniqueness of solutions with the assistance of the Leray–Schauder alternative theorem and Banach’s contraction principle. In addition, by using some mathematical techniques, we examine the stability results of Ulam–Hyers. Finally, we provide one example in order to show the validity of our results.
The Interplay between Digital Entrepreneurship and Sustainable Development in the Context of the EU Digital Economy: A Multivariate Analysis
Authors: Herman Emilia
Published: May 2022

A real challenge for the EU economy and society is to achieve both green and digital transitions in order to tackle the major economic, social and environmental issues faced by EU member states. In this context, digital entrepreneurship, which lies at the intersection of digital technologies and entrepreneurship, has recently benefited from increasing attention both in theoretical and empirical research and in strategic policies. Given these aspects, the aim of this article was to investigate the interrelationship between digital entrepreneurship and productive and innovative entrepreneurship and its impact on the achievement of the Sustainable Development Goals (SDGs) in EU countries. The results of correlation and regression analysis revealed that digital entrepreneurship, which implies productive and innovative entrepreneurial activities, is positively influenced by the degree of a country’s digitalization and, in turn, has a positive impact on the achievement of the SDGs (Total SDGs, SDG 8 and SDG 9). Furthermore, the findings of the principal component analysis and cluster analysis emphasize that there are differences and common features between EU countries in terms of the interrelationship between digital entrepreneurship, digitalization, economic development, national competitiveness and achievement of the SDGs. Therefore, specific measures should be implemented to boost digital entrepreneurship (especially in some central and eastern EU countries) so that this will be the key driver for sustainable development.
Analysis of a MAP/M/1/N Queue with Periodic and Non-Periodic Piecewise Constant Input Rate
Authors: Vishnevsky Vladimir , Vytovtov Konstantin , Barabanova Elizaveta , Semenova Olga
Published: May 2022

This paper considers a queuing system with a finite buffer, a constant main MAP flow, and an additional periodic (non-periodic) Poisson piecewise-constant flow of customers. The eigenvalues of the probability translation matrix of a Kolmogorov system with constant input intensities is analyzed. The definition of the transition mode time based on the analysis of the probability translation matrix determinant is introduced for the first time. An analytical solution to the Kolmogorov equation system for a queuing system with piecewise constant arrival and service intensities is found, the solutions for a queuing system with periodic arrival and service intensities are analyzed, and numerical calculations illustrating this approach are presented.
On the Dynamics in Decoupling Buffers in Mass Manufacturing Lines: A Stochastic Approach
Authors: Pérez-Lechuga Gilberto , Venegas-Martínez Francisco , Montufar-Benítez Marco A. , Mora-Vargas Jaime
Published: May 2022

This paper analyzes the flow of the contents of interleaved buffers with continuously operating machines in a mass production line. Under this framework, the products to be manufactured advance from station to station to receive a physical–chemical transformation that adds value as they progress in the process. The existence of decoupling buffers between operations (between two consecutive workstations) is a common practice in order to alleviate the pressure that is ahead due to the lack of synchronization between consecutive operations, which causes leisure and/or bottlenecks in the system. In this proposal, we analyze the dynamics of a mass manufacturing line with intermediate decoupling buffers. To do that, we use a regenerative stochastic process approach to build a model where the products stored in each buffer are taken all at once by the consecutive machine. In a second approach, we use a homogeneous birth–death process with constant input–output and assume that the products are taken one by one by the consecutive machine. Finally, we use a non-homogeneous birth–death process to analyze the dynamics of a system whose inputs and outputs depend on time. These proposals are accompanied by numerical examples that illustrate its practical utility.
Cell-Free Massive MIMO with Energy-Efficient Downlink Operation in Industrial IoT
Authors: Chen Xiaomin , Zhao Taotao , Sun Qiang , Hu Qiaosheng , Xu Miaomiao
Published: May 2022

Cell-free massive Multi-input Multi-output (MIMO) can offer higher spectral efficiency compared with cellular massive MIMO by providing services to users through the collaboration of distributed APs, and cell-free massive MIMO systems with distributed operations are attracting a great deal of industry attention due to their simplicity and ease of deployment. This paper aims to find an optimal solution for energy efficiency in the downlink operation in the Industrial Internet based on cell-free massive MIMO systems with distributed operations. A system model is proposed, and a theoretical analysis on energy efficiency is presented. The optimization problem of efficient downlink operation is formulated as a mixed-integer nonlinear programming (MINLP) problem, which is further decomposed into two sub-problems, i.e., maximizing the sum-rate of the downlink transmission and optimizing the total energy consumption. The two sub-problems are addressed via AP selection and power allocation, respectively. The simulation results demonstrate that our algorithms can significantly improve the energy efficiency with low computational complexity in comparison with traditional distributed cell-free massive MIMO. Even in the presence of pilot contamination, the proposed algorithms can still provide significant energy efficiency when a large number of IoTDs are connected.
Numerical Calculation Method of Target Damage Effectiveness Evaluation under Uncertain Information of Warhead Fragments
Authors: Li Hanshan , Hao Yun , Zhang Xiaoqian
Published: May 2022

In order to scientifically evaluate the target damage effectiveness when warhead fragments formed by projectile explosion attack targets, this paper proposes a new method by using the multi-layer warhead fragments distribution division mechanism to study an evaluation and calculation model of target damage effectiveness under uncertain information of warhead fragments. On the basis of the spatial relationship between projectile explosion position and target, we first analyze the target damage rules based on the target’s own vulnerability characteristics. Then we use the fuzzy prior probability theory to establish the membership function of the target damage factor and an evaluation model of the target damage grade, and use the stochastic multi-criteria acceptability analysis method to obtain the evaluation index value of the target damage level. Finally, considering the ratio between the effective area of the warhead fragment group attacking target and the area of target itself and the effective number and area ratio of warhead fragments penetrating target, we give a numerical calculation method of target damage effectiveness. Through simulation and calculation, the results show that when the distance between the projectile explosion position and the target is less than 7 m and the coordinate interval of the projectile flight direction is −2.5 m to 2.5 m, the damage probability of warhead fragments to the target is greater than 75%. When the weight of the damage factor of the target changes, the damage effectiveness of the target also changes, and this result is in accordance with the actual experiment, which verifies the rationality of the proposed mathematical model.