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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 426 journals)
Showing 1 - 200 of 265 Journals sorted alphabetically
AAS Open Research     Open Access  
ABC Journal of Advanced Research     Open Access  
Accountability in Research: Policies and Quality Assurance     Hybrid Journal   (Followers: 17)
Acta Materialia Transilvanica     Open Access  
Acta Nova     Open Access  
Acta Scientifica Malaysia     Open Access  
Acta Scientifica Naturalis     Open Access   (Followers: 2)
Adıyaman University Journal of Science     Open Access  
Advanced Science     Open Access   (Followers: 12)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 3)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 2)
Advances in Research     Open Access  
Advances in Science and Technology     Full-text available via subscription   (Followers: 16)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 7)
Afrique Science : Revue Internationale des Sciences et Technologie     Open Access   (Followers: 4)
AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 2)
American Academic & Scholarly Research Journal     Open Access   (Followers: 4)
American Journal of Applied Sciences     Open Access   (Followers: 21)
American Journal of Humanities and Social Sciences     Open Access   (Followers: 10)
American Scientist     Full-text available via subscription   (Followers: 12)
ANALES de la Universidad Central del Ecuador     Open Access   (Followers: 1)
Anales del Instituto de la Patagonia     Open Access  
Applied Mathematics and Nonlinear Sciences     Open Access  
Apuntes de Ciencia & Sociedad     Open Access  
Arab Journal of Basic and Applied Sciences     Open Access  
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 1)
Archives Internationales d'Histoire des Sciences     Partially Free   (Followers: 5)
Archives of Current Research International     Open Access  
ARO. The Scientific Journal of Koya University     Open Access  
ARPHA Conference Abstracts     Open Access   (Followers: 1)
ARPHA Proceedings     Open Access  
ArtefaCToS : Revista de estudios sobre la ciencia y la tecnología     Open Access  
Asian Journal of Advanced Research and Reports     Open Access   (Followers: 1)
Asian Journal of Applied Science and Engineering     Open Access  
Asian Journal of Scientific Research     Open Access   (Followers: 2)
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 5)
Australian Field Ornithology     Full-text available via subscription   (Followers: 2)
Australian Journal of Social Issues     Hybrid Journal   (Followers: 7)
Avrasya Terim Dergisi     Open Access  
Bangladesh Journal of Scientific Research     Open Access  
Beni-Suef University Journal of Basic and Applied Sciences     Open Access  
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 10)
Berkeley Scientific Journal     Full-text available via subscription  
BIBECHANA     Open Access  
BibNum     Open Access  
Bilge International Journal of Science and Technology Research     Open Access   (Followers: 1)
Bioethics Research Notes     Full-text available via subscription   (Followers: 16)
BJHS Themes     Open Access  
Black Sea Journal of Engineering and Science     Open Access  
Borneo Journal of Resource Science and Technology     Open Access  
Bulletin de la Société Royale des Sciences de Liège     Open Access  
Bulletin of the National Research Centre     Open Access  
Butlletí de la Institució Catalana d'Història Natural     Open Access  
Central European Journal of Clinical Research     Open Access  
Chain Reaction     Full-text available via subscription  
Ciencia Amazónica (Iquitos)     Open Access  
Ciencia en Desarrollo     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencia Ergo Sum     Open Access  
Ciência ET Praxis     Open Access  
Ciencia y Tecnología     Open Access  
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Citizen Science : Theory and Practice     Open Access   (Followers: 1)
Communications Faculty of Sciences University of Ankara Series A2-A3 Physical Sciences and Engineering     Open Access  
Communications in Applied Sciences     Open Access  
Comunicata Scientiae     Open Access  
ConCiencia     Open Access  
Conference Papers in Science     Open Access  
Configurations     Full-text available via subscription   (Followers: 11)
COSMOS     Hybrid Journal   (Followers: 1)
Crea Ciencia Revista Científica     Open Access  
Cuadernos de Investigación UNED     Open Access  
Current Issues in Criminal Justice     Hybrid Journal   (Followers: 14)
Current Research in Geoscience     Open Access   (Followers: 6)
Dalat University Journal of Science     Open Access  
Data     Open Access   (Followers: 4)
Data Curation Profiles Directory     Open Access   (Followers: 4)
Dhaka University Journal of Science     Open Access  
Dharmakarya     Open Access  
Diálogos Interdisciplinares     Open Access  
Digithum     Open Access   (Followers: 2)
Discover Sustainability     Open Access   (Followers: 2)
Einstein (São Paulo)     Open Access  
Ekaia : EHUko Zientzia eta Teknologia aldizkaria     Open Access  
Elkawnie : Journal of Islamic Science and Technology     Open Access  
Emergent Scientist     Open Access  
Enhancing Learning in the Social Sciences     Open Access   (Followers: 6)
Enseñanza de las Ciencias : Revista de Investigación y Experiencias Didácticas     Open Access  
Entramado     Open Access  
Entre Ciencia e Ingeniería     Open Access  
Epiphany     Open Access   (Followers: 1)
Estação Científica (UNIFAP)     Open Access  
Ethiopian Journal of Education and Sciences     Open Access   (Followers: 5)
Ethiopian Journal of Science and Technology     Open Access  
Ethiopian Journal of Sciences and Sustainable Development     Open Access  
European Online Journal of Natural and Social Sciences     Open Access   (Followers: 4)
European Scientific Journal     Open Access   (Followers: 2)
Evidência - Ciência e Biotecnologia - Interdisciplinar     Open Access  
Exchanges : the Warwick Research Journal     Open Access   (Followers: 1)
Experimental Results     Open Access  
Extensionismo, Innovación y Transferencia Tecnológica     Open Access  
Facets     Open Access  
Fides et Ratio : Revista de Difusión Cultural y Científica     Open Access  
Fırat University Turkish Journal of Science & Technology     Open Access  
Fontanus     Open Access  
Forensic Science Policy & Management: An International Journal     Hybrid Journal   (Followers: 239)
Frontiers for Young Minds     Open Access  
Frontiers in Climate     Open Access   (Followers: 3)
Frontiers in Science     Open Access   (Followers: 1)
Fundamental Research     Open Access   (Followers: 4)
Futures & Foresight Science     Hybrid Journal   (Followers: 2)
Gaudium Sciendi     Open Access  
Gazi University Journal of Science     Open Access  
Ghana Studies     Full-text available via subscription   (Followers: 14)
Global Journal of Pure and Applied Sciences     Full-text available via subscription  
Global Journal of Science Frontier Research     Open Access   (Followers: 1)
Globe, The     Full-text available via subscription   (Followers: 3)
HardwareX     Open Access  
Heidelberger Jahrbücher Online     Open Access  
Heliyon     Open Access  
Himalayan Journal of Science and Technology     Open Access  
History of Science and Technology     Open Access   (Followers: 1)
Hoosier Science Teacher     Open Access  
Impact     Open Access   (Followers: 1)
Indian Journal of History of Science     Hybrid Journal  
Indonesian Journal of Fundamental Sciences     Open Access  
Indonesian Journal of Science and Mathematics Education     Open Access   (Followers: 1)
Indonesian Journal of Science and Technology     Open Access  
Ingenieria y Ciencia     Open Access   (Followers: 1)
Innovare : Revista de ciencia y tecnología     Open Access  
Integrated Research Advances     Open Access  
Interciencia     Open Access  
Interface Focus     Full-text available via subscription  
International Annals of Science     Open Access  
International Archives of Science and Technology     Open Access  
International Journal of Academic Research in Business, Arts & Science     Open Access  
International Journal of Advanced Multidisciplinary Research and Review     Open Access  
International Journal of Applied Science     Open Access  
International Journal of Basic and Applied Sciences     Open Access   (Followers: 1)
International Journal of Computational and Experimental Science and Engineering (IJCESEN)     Open Access  
International Journal of Culture and Modernity     Open Access  
International Journal of Engineering, Science and Technology     Open Access  
International Journal of Engineering, Technology and Natural Sciences     Open Access  
International Journal of Innovation and Applied Studies     Open Access   (Followers: 3)
International Journal of Innovative Research and Scientific Studies     Open Access   (Followers: 1)
International Journal of Network Science     Hybrid Journal   (Followers: 3)
International Journal of Recent Contributions from Engineering, Science & IT     Open Access  
International Journal of Research in Science     Open Access   (Followers: 1)
International Journal of Science & Emerging Technologies     Open Access   (Followers: 1)
International Journal of Social Sciences and Management     Open Access   (Followers: 2)
International Journal of Technology Policy and Law     Hybrid Journal   (Followers: 6)
International Letters of Social and Humanistic Sciences     Open Access  
International Scientific and Vocational Studies Journal     Open Access  
InterSciencePlace     Open Access  
Investiga : TEC     Open Access  
Investigación Joven     Open Access  
Investigacion y Ciencia     Open Access   (Followers: 1)
Iranian Journal of Science and Technology, Transactions A : Science     Hybrid Journal  
iScience     Open Access   (Followers: 1)
Issues in Science & Technology     Free   (Followers: 7)
Ithaca : Viaggio nella Scienza     Open Access  
Jaunujų mokslininkų darbai     Open Access  
Journal de la Recherche Scientifique de l'Universite de Lome     Full-text available via subscription  
Journal of Chromatography & Separation Techniques     Open Access   (Followers: 10)
Journal of Advanced Research     Open Access   (Followers: 2)
Journal of Al-Qadisiyah for Pure Science     Open Access  
Journal of Alasmarya University     Open Access  
Journal of Analytical Science & Technology     Open Access   (Followers: 4)
Journal of Applied Science and Technology     Full-text available via subscription   (Followers: 1)
Journal of Applied Sciences and Environmental Management     Open Access   (Followers: 1)
Journal of Big History     Open Access   (Followers: 3)
Journal of Composites Science     Open Access   (Followers: 3)
Journal of Deliberative Mechanisms in Science     Open Access  
Journal of Diversity Management     Open Access   (Followers: 4)
Journal of Indian Council of Philosophical Research     Hybrid Journal  
Journal of Institute of Science and Technology     Open Access  
Journal of Integrated Science and Technology     Open Access  
Journal of Kerbala University     Open Access  
Journal of King Saud University - Science     Open Access  
Journal of Mathematical and Fundamental Sciences     Open Access  
Journal of Natural Sciences and Mathematics Research     Open Access  
Journal of Natural Sciences Research     Open Access   (Followers: 1)
Journal of Negative and No Positive Results     Open Access  
Journal of Responsible Technology     Open Access  
Journal of Science (JSc)     Open Access  
Journal of Science and Engineering     Open Access  
Journal of Science and Technology     Open Access   (Followers: 2)
Journal of Science and Technology     Open Access   (Followers: 1)
Journal of Science and Technology (Ghana)     Open Access   (Followers: 3)
Journal of Science and Technology Policy Management     Hybrid Journal   (Followers: 1)
Journal of Science Foundation     Open Access   (Followers: 1)
Journal of Science of the University of Kelaniya Sri Lanka     Open Access  
Journal of Scientific Research     Open Access  
Journal of Scientific Research and Reports     Open Access  
Journal of Scientometric Research     Open Access   (Followers: 19)
Journal of Shanghai Jiaotong University (Science)     Hybrid Journal  
Journal of Social Science Research     Open Access   (Followers: 2)
Journal of Taibah University for Science     Open Access  
Journal of the Asiatic Society of Bangladesh, Science     Open Access  

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Arabian Journal for Science and Engineering
Journal Prestige (SJR): 0.303
Citation Impact (citeScore): 1
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2193-567X - ISSN (Online) 2191-4281
Published by Springer-Verlag Homepage  [2469 journals]
  • The Prediction of Ground Settlement of a Box Culvert Jacked Under the
           Action of an Ultra-Shallow Buried Pipe Curtain

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      Abstract: With the development of three-dimensional (3D) underground space, the jacking method of a pipe curtain box culvert has received greater attention due to its unique advantages in controlling the ground settlement. This paper proposes a new method for predicting ground settlement during box culvert jacking under the action of an ultra-shallow buried pipe curtain and then reveals the influence of jacking force and grouting rate on ground settlement. The results show that the calculation method based on stochastic medium theory and the Navier solution of the elastic sheet model can predict the ground settlement caused by volume loss of jacking and deformation of a pipe-roof. During the excavation of the passage, the deformation of the ground monitoring points is uplift, micro-uplift, and settlement. The settlement trough on a cross section is W-shaped; the closer to the cross section in the middle of the passageway, the greater the ground settlement. Moreover, when the jacking force is less than 40 kPa, the total settlement decreases with an increase in the jacking force. The scope of the W-type settlement profile is not affected by the jacking force and the grouting rate can significantly control ground settlement. Changing the grouting rate will affect the scope of the W-type settlement profile. An insufficient grouting rate will widen the gap of the ground settlement between the initial cross section, arrival cross section, and cross section in the middle of the passageway.
      PubDate: 2022-01-23
       
  • A Recommender System Integrating Long Short-Term Memory and Latent Factor

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      Abstract: Recommender system is designed to model user’s interests based on their historical behavior. Recommended information meets the user’s interests and needs by itself without users providing explicit requirements. It can solve the problem of ”information overload” caused by the information explosion and the popularity of large data effectively. This paper put forward an LSTM-LFM recommender system that fused long short-term memory and latent factor models. This system can divide into two parts: the first part is a prediction of the user’s interestingness in the item’s name. First use the word2ver method to vectorize the item’s name, then establish positive and negative sample training data, and train the LSTM model, thus implementing the prediction of the user’s interestingness in the item’s name. The second part is the extraction and characterization of the item’s latent factor vector. In this paper, the user’s interestingness in the item’s name is introduced into the LFM model to train and obtain the latent factor matrix which integrates the user’s interestingness in the item’s name. Each column vector of the latent factor matrix represents the unique latent factor vector corresponding to each item. At last, by predicting the user’s interestingness to items, the most interesting items are recommended to the user as a recommendation list. In this paper, the comparison experiment on the MovieLens dataset verifies that this recommendation system that integrates long and short-term memory and latent factor is superior to the traditional UserCF, ItemCF, and LFM algorithms in precision and recall rate.
      PubDate: 2022-01-23
       
  • Arabic Handwritten Recognition Using Deep Learning: A Survey

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      Abstract: In recent times, many research projects and experiments target machines that automatically recognize handwritten characters, but most of them are done in Latin. Recognizing handwritten Arabic characters is a complicated process compared to English and other languages as a nature of Arabic words. In the past few years, deep learning approaches have been increasingly used in the field of Arabic recognition. This paper aims to categorize, analyze and presents a comprehensive survey in Arabic handwritten recognition literature, focusing on state-of-the-art methods for deep learning in feature extraction. The paper focuses on offline text recognition, with a detailed discussion of the systematic analysis of the literature. Additionally, the paper is critically analyzing the current literature and identifying the problem areas and challenges faced by the previous studies. After investigating the studies, a new classification of the literature is proposed. Besides, an analysis is performed based on the findings, and several issues and challenges related to the recognition of Arabic scripts are discussed.
      PubDate: 2022-01-23
       
  • Optimization of Asymmetric Bioreduction Conditions of
           2-methyl-1-phenylpropan-1-one by Lactobacillus fermentum BY35 Using
           I-Optimal Design-Based Model

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      Abstract: The bioreduction of prochiral ketones offers efficient access to chiral secondary alcohols, which are potentially beneficial precursors for producing many biologically active compounds and natural products. This bioreduction process can be affected by different parameters when whole-cell of biocatalysts such as Lactic Acid Bacteria strains are applied. In this context, this paper proposed an I-optimal design-based model to optimize culture parameters such as temperature, pH, incubation period, and agitation speed for asymmetric bioreduction of 2-methyl-1-phenylpropan-1-one (1) with Lactobacillus fermentum BY35 as a biocatalyst while achieving the highest conversion rate (cr) and enantiomeric excess (ee). The optimum settings of the four culture parameters and the cr and ee values were found using the proposed optimization model as follows: pH = 6.5, temperature = 25 °C, incubation period = 38.5 h, agitation speed = 200 rpm, the ee value = 98.78%, and the cr value = 98.92%. After the validation of the process, the cr and ee values were found to be > 99% and > 99%, respectively, while using the optimum operating conditions from the optimization model. Thus, the results of the optimization model are consistent with the results of the validation experiment. It is also noted that this paper is the first to optimize culture parameters using the proposed I-optimal design-based model for an asymmetric reduction.
      PubDate: 2022-01-23
       
  • Corrosion of Additively Manufactured Metallic Components: A Review

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      Abstract: The unique additive manufacturing (AM) attributes such as tool-less design, on-site fabrication, short production cycle, and complex structures fabrication can make AM market penetration deeper. The sustained improvements in AM’s computational hardware and software, advanced automation, affordable equipment, and process, structural, and metallurgical understanding are likely to contribute to AMs’ more comprehensive commercial adaptation. However, several scientific and technological issues like process-induced defects and microstructural heterogeneity limit its growth in replacing conventional products. AM mechanical properties are comparable to those produced conventionally, and the same is true about its corrosion behavior. However, AM process uncertainties can vary part properties, causing significant discrepancies in corrosion results. Controlling corrosion in AM alloys requires a proper understanding of the process and microstructural evolution. Optimizing processing conditions is critical for part’s high productivity and minimal defects. Similarly, post-processing conditions are vital to infuse desired mechanical and chemical properties. Regardless of the processing conditions, corrosion is integral to material stability that needs scientific input to understand and develop mechanical and microstructural properties for excellent corrosion-resistant AM materials. This study aims to analyze the scientific work done in the corrosion analysis of AM materials and to suggest future work potentials.
      PubDate: 2022-01-23
       
  • Thermal Stimulation of Sedimentary Rocks: Experimental Investigation on
           Local Khuff Limestone and Biyadh Sandstone

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      Abstract: The current stimulation practice of hydraulic fracturing relies on injection of water-based fluids; however, water can cause significant formation damage, therefore, alternative fracturing methods are an option. The concept of thermal stimulation rests on the idea that a very cold liquid can induce fracture when brought into contact with warmer rock under reservoir conditions. The mechanism for fracture creation consists of a severe thermal shock that imparts to the rock when its volume near the interface rapidly contracts, as the rock loses its heat. In this study, simple laboratory testing was performed to investigate the effectiveness of thermal stresses on the strength of dry and brine saturated rock samples representing two local formations namely Khuff limestone and Biyadh sandstone. Unconfined compressive strength (UCS) of dry rocks were determined and Khuff limestone showed 37% higher UCS value than Biyadh sandstone samples investigated and all appeared to fail along a vertical shear plane with load application. Brine saturated samples of both rock types suffered of water softening effect inducing UCS reduction of 51% and 42.3% for both limestone and sandstone samples, respectively. When dry and brine saturated rock samples of the two types were exposed to thermal stresses induced by exposure to liquid Nitrogen (LN2), both experienced strong thermal gradients reducing rock strength proving the effectiveness of the process. Dry samples experienced axial splitting type fractures upon loading with UCS reduction of 37% and 64% for limestone and sandstone, respectively. Brine saturated samples suffered imminent failure and no loading was needed indicating that strengths of both rocks were completely diminished upon LN2 exposure. Water expansion due to freezing counteracted by the shrinkage of the rock matrix believed to be the reason behind the imminent rock splitting.
      PubDate: 2022-01-23
       
  • VMFCVD: An Optimized Framework to Combat Volumetric DDoS Attacks using
           Machine Learning

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      Abstract: Despite significant development in distributed denial of service (DDoS) defense systems, the downtime caused by DDoS damages reputation, crushes end-user experience, and leads to considerable revenue loss. Volumetric DDoS attacks are the most common form of DDoS attack and are carried out by an army of infected IoT devices or by reflector servers, which increase attacks at massive scales. In this work, we propose a voting-based multimode framework to combat volumetric DDoS (VMFCVD) attacks. VMFCVD is based on a triad of fast detection mode (FDM), defensive fast detection mode (DFDM), and high accuracy mode (HAM) methods. FDM is designed to classify network traffic when the server is under attack. The highly dimensionally reduced dataset helps FDM accelerate detection speed. During our experiment, the dimension reduction for FDM was more than 97% while maintaining an accuracy of 99.9% in most cases. DFDM is an extended version of FDM that enhances malicious network traffic detection accuracy by tightening the detection technique. HAM focuses on detection accuracy, showing substantial improvement over FDM and DFDM. HAM activates when the server is stable. VMFCVD is extensively experimented on the latest benchmark DDoS and botnet datasets, namely the CICIDS2017 (BoT & DDoS), CSE-CIC-IDS2018 (BoT & DDoS), CICDDoS2019 (DNS, LDAP, SSDP & SYN), DoHBrw2020, NBaIoT2018 (Mirai), UNSW2018 BoTIoT, and UNSW NB15 datasets. The VMFCVD results show that it outperforms recent studies. VMFCVD performs exceptionally well when the server is under DDoS attack.
      PubDate: 2022-01-23
       
  • Tribological Characteristics of GNPs and HNTs as Lubricant Additives in an
           Aluminum-Based Hybrid Composite-Steel Contact

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      Abstract: Tribological performance comparison of Graphene nanoplatelet and Halloysite clay nanotube-based nanolubricants in an aluminum-based hybrid composite/steel tribo-contact was addressed by suspending nanoparticles in concentrations of 0.025, 0.05, 0.1 and 0.5%wt within SAE 5W40 motor oil. Dispersion stability and thermophysical properties of the designed nanolubricants were also evaluated. In order to perform tribological experiments by using a pin-on-ring configuration tribometer at various loads and rotation speeds, a hybrid composite was fabricated by powder metallurgy-extrusion method and characterized. The lubrication regime was characterized using stribeck curves and minimum film thickness. The worn surfaces morphology of the pin materials were characterized by Scanning electron microscopy images, Energy-dispersive X-ray spectroscopy and surface roughness measurements. The obtained highest friction coefficient and wear rate reductions were 40 and 36% with 0.5%wt Graphene nanoplatelet, and 25 and 10% for 0.1%wt Halloysite clay nanotube-based nanolubricants, respectively, during a mixed lubrication regime. The wear mechanism on the worn surface of the hybrid composite was predominantly abrasive with plastic yielding and delamination. Scanning electron microscopy images, Energy-dispersive X-ray spectroscopy and surface roughness measurements confirmed the Graphene nanoplatelet and Halloysite clay nanotube deposition on the worn surfaces and the formation of tribo-films that protect the sliding contacts.
      PubDate: 2022-01-22
       
  • A DFT Spectrum Acoustic Analysis for Investigating Pulse Duration Effect
           on Performance, Psychoacoustic Sound Level of Turbocharger Turbines
           Through C +  + FDM Code

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      Abstract: The turbocharger turbine operates under high-time-fluctuating flow conditions, originated from the reciprocating motion of the engine pistons and its head valves fast closure and opening. The turbocharger turbine performance and acoustic characteristics are highly affected by the pulsating nature of the engine exhaust flow. As acoustic levels of sound usually recorded around turbocharger turbines coupled to engines is in the frequency range so heard by humans, it seems necessary to get a clear insight about its acoustic characteristics whether it contributes to the noise generation or its reduction as this work suggests. Unlike the common technique of linear acoustic characterization based on the transfer matrix theory of plane waves, the present study investigates the acoustic characteristics of one turbocharger turbine for different pulse durations of the flow using a finite difference method (FDM) gas dynamics solver developed with the C +  + programming language. In this study, four pulse duration to period ratios of 25%, 50%, 75% and 100% were considered. Based on the pressure transient profiles, a nonlinear acoustic analysis relying on the short time Fourier transform (STFT) was conducted to seek out the effect of the pulse duration to period ratio on the noise generation and transmission loss of the turbine. Results revealed that the turbine plays an acoustically active and passive roles at the same time depending on the spectrum frequency. Results confirmed a significant noise reduction with a decreasing pulse duration to period ratio.
      PubDate: 2022-01-22
       
  • Correction to: A Fused Heterogeneous Deep Neural Network and Robust
           Feature Selection Framework for Human Actions Recognition

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      Abstract: A Correction to this paper has been published: 10.1007/s13369-021-05881-4
      PubDate: 2022-01-20
       
  • Structure and Electric Characterizations of the Derived Nanocrystalline
           Hydroxyapatite from Strombidae Strombus Seashells

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      Abstract: Strombidae strombus seashells have been used as calcium precursors to prepare nanocrystalline hydroxyapatite (HAp) via a wet chemical route. The as-prepared HAp powder has been investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and complex impedance spectroscopy to examine the morphology, elemental composition, crystal structure, functional groups, and electric properties. The synthesized HAp exhibits a single and nanocrystalline (23 nm crystallite size) hexagonal structure with lattice parameters a = 9.3819 ± 10–4 Å and c = 6.8927 ± 10–4 Å. FT-IR and Raman spectroscopy results confirm the presence of P−O, O− H, and C−O bonds. The AC conductivity is frequency and temperature-dependent. The activation energy values are in the range of 0.238−0.319 eV, and the conduction mechanism proceeds by proton hopping. The Nyquist plots are modeled by an equivalent circuit composed of (Rg//CPEg) + (Rgb//L//CPEgb) elements.
      PubDate: 2022-01-20
       
  • Investigating Static and Dynamic Behavior of the Strain Gauge Type
           Pressure Sensor in Exposure to Thermal Stresses

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      Abstract: Due to the extreme importance of pressure measurement in various industrial applications, studying different types of failures possible in a pressure sensor seems to be very necessary. The presented research analyses thermally affected faults in a strain gauge type pressure sensor. The studied electro-mechanical sensor is composed of a thick plate and a very thin membrane in direct contact with the fluid whose pressure is being measured. The membrane is connected to the sensing plate via the incompressible interface fluid (silicone oil). The temperature difference between the membrane and the body of the sensor creates thermal stresses in the membrane. The equations governing the motion of the sensing plate and membrane in the presence of temperature differences have been presented and solved simultaneously. The occurrence of the buckling phenomenon is studied for the first and second deformation modes of the membrane. It has been shown that in the second deformation mode of the membrane, the existing coupling between the membrane and the plate vanishes which leads to the decrement of the equivalent stiffness of the structure. Therefore, the probability of the occurrence of the buckling phenomenon in the membrane increases significantly compared to the first deformation mode. The effect of geometrical parameters of the sensor on the measurable pressure range of the sensor is investigated in detail. The transient response of the sensor subjected to the dynamic pressure force is studied. The effect of nonlinear terms on the frequency response of the sensor has also been examined.
      PubDate: 2022-01-20
       
  • Energy, Exergy, and Advanced Exergy Analysis of a Cogeneration System
           Combined with a Drying Unit of Phosphate Fertilizers

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      Abstract: This work assesses cogeneration system's thermodynamic efficiency installed upstream of a rotary drying unit used to dry monocalcium phosphate products in a fertilizers production complex in Safi, Morocco. The choice of the technology for cogeneration depends on the heating requirement of the system. The case studied requires the generation of hot gases recycled to the dryer to reduce the product moisture. The thermodynamic performances are evaluated using energy, exergy, and advanced exergy analysis. The results of the energy analysis show that 89.6% of the system's total heat loss occurs in the rotary dryer and the combustion chamber. The same conclusion is drawn within the conventional exergy analysis. The combustion chamber accounts for more than half of the system's total exergy destruction rate. The exergy improvement potential is, respectively, found to be 29.87, 28.55, 0.378, and 0.07 MWt in the rotary dryer, the combustion chamber, the gas turbine, and the air compressor. Advanced exergy analysis is carried out. The results show that 64% of the system's total exergy destruction rate is unavoidable and more than 84% is exogenous. The splitting of the exogenous exergy destruction rate of each component shows that the combustion chamber is the most important contributor to the exogenous exergy destruction value within all components. The results indicate that more than 60% of the total exergy destruction is unavoidable endogenous, which means that the total exergy destruction in the overall system cannot be lower than 96.42 MWt.
      PubDate: 2022-01-20
       
  • Synergistic Effect of Imidazoline Derivative and Benzimidazole as
           Corrosion Inhibitors for Q235 Steel: An Electrochemical, XPS, FT-IR and MD
           Study

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      Abstract: The corrosion inhibition effect and synergistic mechanism of novel imidazoline derivative (SMIF) and benzimidazole (BMZ) in 3.5 wt% simulated concrete solution were studied experimentally and theoretically. The complex inhibitors have the most outstanding inhibition efficiency when SMIF concentration is 0.1 g/L and BMZ is 0.9 g/L, the corrosion inhibition efficiencies of weight loss, Electrochemical Impedance Spectroscopy and Potentiodynamic polarization curve (Tafel) were 88.81%, 86.27% and 90.22%, respectively. Electrochemistry analysis results proved that the corrosion inhibition mechanism of the inhibitors in the corrosion solution was mainly the formation of a protective film on the surface of carbon steel. FT-IR, Energy Dispersive Spectroscopy and X-ray Photoelectron Spectroscopy all proved the existence of the protective film. Molecular dynamics proved that the composite inhibitor molecules could be stable on the surface of carbon steel and when consist of complex inhibitor was 0.1 g/L SMIF and 0.9 g/L BMZ the stable adsorption morphology were the highest. This work confirmed that SMIF and BMZ inhibitors have a good synergistic effect, greatly improving the inhibition efficiency and reducing the cost of corrosion inhibition, and has a certain guiding significance for synergistic inhibition.
      PubDate: 2022-01-20
       
  • A Numerical and Experimental Performance Assessment of a Single-Phase
           Supersonic Ejector

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      Abstract: This paper proposes an integrated numerical–experimental study of a fixed geometry ejector designed for a cooling system activated by waste heat. Ejector operation is analyzed for cases of imposed input and output sets of conditions in terms of pressures and/or temperatures. Experiments with constant primary conditions and secondary temperature were conducted in a range of outlet pressures for model validation purposes. A parametric analysis was then performed for constant pressure and temperature conditions at both inputs (primary and secondary) by varying the outlet pressure. For each test case, performance in terms of entrainment ratio, local parameters distributions (P, M, τ) and the internal flow structure were analyzed in an attempt to establish a link between the external constraints, the flow structure, the operation stability and performance within the range of cooling applications. The ranges of operating conditions investigated were Pp = 4.77 bar, Tp = 83 °C and, respectively, 1.7 ≤ Pc ≤ 2.4 bar, 12.5 °C ≤ Te ≤ 16.5 °C, at saturation. Experimental entrainment ratio, ERexp in the range of 0.12–0.22 was numerically simulated within ± 10%. It was shown that both the ejector operation and the internal flow configurations were sensitive to backpressure. More particularly, an optimal backpressure exists to which corresponds an on-design conditions with maximized entrainment ratio and a shock-wave train located at the end of the mixing chamber. A backpressure increase sets the ejector in off design. This mode of operation is characterized by a shift of the shock train toward the inlets, a disturbance of the flow configuration, a diminution of the entrainment ratio and a deterioration of the operation stability. On the other hand, a backpressure decrease does not affect the ejector stability of operation at its maximum entrainment ratio for the prevailing conditions.
      PubDate: 2022-01-20
       
  • Essential Oil Composition, Antimicrobial, Cytotoxic, and Cyclooxygenase
           Inhibitory Areas of Activity of Pistacia lentiscus from Palestine

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      Abstract: The current study aimed to extract and identify the chemical compounds of Pistacia lentiscus essential oil (PLEO) from Palestine and to assess its antimicrobial, cytotoxic, and cyclooxygenase (COX) inhibitory activities. The hydro-distilled PLEO was analyzed utilizing the gas chromatography-mass spectroscopy (GC–MS) apparatus. Pistacia lentiscus essential oil (PLEO) was tested for its antimicrobial properties utilizing a broth microdilution method. In addition, an MTS assay was employed to test the cytotoxic activity on a cervical cancer cell line (HeLa). An in-vitro COX inhibition test kit was used to measure the COX inhibitory activity. Twenty-nine molecules were characterized, representing 100% of the total PLEO. Limonene (43.78%), α-pinene (29.45%), and β-pinene (7.54%) were characterized as the major PLEO components. The results revealed that PLEO has broad-spectrum antimicrobial activity against the tested microbial strains and has cytotoxic activity against HeLa cancer cells with an IC50 value of 169.68 ± 2.56 μg/ml. Promising COX-1 and COX-2 inhibitory activities were also demonstrated. The chemical components of PLEO from Palestine were identified here for the first time and showed biological effects against the screened microbes, HeLa cells, and COX enzyme. Further in-vivo investigations are required to assess these activities and other pharmacological effects.
      PubDate: 2022-01-20
       
  • The Experimental Investigation on Progressive Deformation of Shear Slip
           Surface Based on Acoustic Emission Measurements

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      Abstract: The sliding surface deformation of the soil slope mainly presents progressive failure characteristics, and serial acoustic emission (AE) signals are generated during the deformation process of progressive landslide. Early warning systems for soil slope instability should alert users of slope deformation stage to make the right decision. Thus, a model test aiming at reproducing the typical shear surface deformation of a soil slope is designed. The displacement, AE data and corresponding time–frequency characteristics are comprehensively analyzed to evaluate the progressive deformation behavior. Comparisons with different granular backfills measurements show that cumulative AE count increases proportionally with the shear surface displacement, and the experiments demonstrate that the glass sand backfill exhibits remarkable AE detection characteristics and stronger correlation results. Significantly, AE signal exhibits variant dominant frequencies at different deformation stages, and there is the significant phenomenon that not only the low-frequency signals generated with a significantly increase number, at the same time the continuous high-frequency signals appear during the accelerating deformation stage. Furthermore, from the statistical trend of the energy percentage of the high-frequency band into 312.5–500 kHz, it is found that the correlative energy proportion occupies up to 15%, or even higher during the accelerating stage, indicating that the landslide may be about to enter a severely dangerous stage. This study proposes a new perspective on the frequency characteristics as the early warning index, which can be combined with other traditional acoustic emission indicators to improve the accuracy of the field warning monitoring for the soil progressive landslides.
      PubDate: 2022-01-20
       
  • Thermal–Hydraulic Performance of a V-Groove Solar Air Collector with
           Transverse Wedge-Shaped Ribs

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      Abstract: The poor convective heat transfer coefficient between the absorbing plate and air could result in a decrease in the thermal efficiency of the solar air heater. A semi-analytical model was developed in MATLAB environment was used to predict the thermal–hydraulic efficiency (ηeff) of a V-groove solar air collector (VSAC) integrated with transverse wedge-shaped ribs (TWSR) beneath the absorbing plate. The influence of design parameters, namely pitch ratio (p/e) of 5.67–15, and relative height ratio (e/Dh) of 0.02–0.07, on the thermal–hydraulic efficiency is investigated, with mass flowrates of 0.021–0.126 kg/s. The optimal values of p/e and e/Dh are examined using data for actual climatic conditions. The results indicate that the ηeff of the VSAC-TWSR is greater than that of the smooth VSAC. Moreover, the ηeff increases with increasing flowrates to a specific value and then decreases while thermal efficiency is directly proportional to the mass flowrates. In addition, the optimal thermal enhancement is achieved at p/e = 8 and e/Dh = 0.07. The thermal efficiency increases by about 8% when ribbed as opposed to smooth surface are used. The heat gain of a proposed design enhanced by about 9% and the maximum increase in the thermal–hydraulic efficiency is 9.6% compared to the smooth design when the mass flowrate is 0.084 kg/s.
      PubDate: 2022-01-20
       
  • $$H_{\infty }$$ H ∞ Controller Design for Frequency Control of Delayed
           Power System with Actuator Saturation and Wind Source Integration

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      Abstract: Inclusion of wind energy in power system network increases complexity of load frequency control (LFC). Time-delay and actuator saturation are two inevitable phenomena in LFC. This paper studies the problem on LFC design of wind-integrated power system (WIPS) considering the effects of actuator saturation and time-delay. Actuator saturation is represented by using two different methods such as polytopic method and sector bounding method. A delayed robust \(H_{\infty }\) load frequency controller design is proposed for WIPS with time-delay and actuator saturation. New delay-dependent \(H_{\infty }\) stabilization criteria with actuator saturation based on Lyapunov–Krasovskii functional are derived in linear matrix inequality framework. A two-area WIPS is considered as a case study to evaluate performance of the proposed LFC design.
      PubDate: 2022-01-19
       
  • Synthesis, Spectroscopic and Biological Investigation of a New Ca(II)
           Complex of Meloxicam as Potential COX-2 Inhibitor

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      Abstract: Drug development on basis of coordination compounds provides versatile structural and functional properties as compared to other organic compounds. In the present study, a new Ca(II) complex of meloxicam was synthesized and characterized by elemental analysis, FT-IR, UV–Vis, 13C NMR, SEM–EDX, powder XRD and thermal analysis (TGA). The Ca(II) complex was investigated for its in vitro, in vivo biological activities and in silico docking analysis against COX-1 and COX-2. The spectral analysis indicates that the meloxicam acts as a deprotonated bidentate ligand (coordinated to the metal atom through the amide oxygen and the nitrogen atom of the thiazolyl ring) in the complex. SEM–EDX and powder XRD analysis depicted crystalline morphology of Ca(II) complex with a crystalline size of 32.86 nm. The in vitro biological activities were evaluated by five different antioxidant methods and COX inhibition assay, while in vivo activities were evaluated by carrageenan-, histamine- and PGE2-induced paw edema methods and acetic acid-induced writhing test. The Ca(II) complex showed prominent antioxidant activities and was found to be more selective toward COX-2 (43.77) than COX-1 as compared to meloxicam. It exhibited lower toxicity (LD50 1000 mg/Kg) and significantly inhibited carrageenan- and PGE2-induced inflammation at 10 mg/Kg (P < 0.05), but no significant effect was observed on histamine-induced inflammation. Moreover, Ca(II) complex significantly reduced the number of writhes induced by acetic acid (P < 0.05). The in silico molecular docking data revealed that Ca(II) complex obstructed COX-2 (dock score 6438) more effectively than COX-1 (dock score 5732) as compared to meloxicam alone.
      PubDate: 2022-01-19
       
 
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