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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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Black Sea Journal of Engineering and Science
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  This is an Open Access Journal Open Access journal
ISSN (Online) 2619-8991
Published by DergiPark Homepage  [185 journals]
  • A New Multi-Criteria Decision Making Approach “Possibilistic Evaluation
           System”: An Application on Participation Funds

    • Authors: Furkan GÖKTAŞ; Fatih GÜÇLÜ
      Abstract: Participation stock umbrella funds are an investment alternative that provides the opportunity to invest in stocks filtered within the framework of Islamic finance principles. Possibility theory is an important tool in decision making. In this study, we propose a new multi-criteria decision making (MCDM) approach based on possibility theory for problems such as comparing participation stock umbrella funds. We call this approach as the Possibilistic Evaluation System (PES). PES is related to the maximin rule, weighted sum method and maximax rule, which are the elementary MCDM methods. We uniquely derive alternatives’ priority vector with PES. In other words, it gives a unique solution for multi-objective decision making problems such as portfolio selection. It depends on selecting the alternative having the highest priority for multi-attribute decision making problems. We illustrate PES by using the real data set of five different participation stock umbrella funds traded in Türkiye between 31.07.2020 and 30.12.2022. In our application, we observe that PES reveals more information than these elementary methods.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Design and Optimization of Voltage Mode PWM Control of DC-DC Buck
           Converter with a PI-Lead Compensator Using the Simulated Annealing
           Algorithm

    • Authors: Kübra DOĞAN; Bülent DAĞ
      Abstract: This paper presents a method for improving the performance of DC-DC Buck Converter Systems using voltage mode Pulse Width Modulation (PWM) control. We explore the effectiveness of Proportional-Integral (PI) and Lead Compensator controllers in enhancing system stability, minimizing voltage fluctuations, and improving load response. The system is modeled through transfer functions, and the controllers' impacts are analyzed both individually and in tandem. A key contribution of this work is the optimization of the PI-Lead Compensator parameters utilizing the Simulated Annealing Algorithm, which is fine-tuned to improve phase margin, gain crossover frequency, and steady state error. These parameters are critical for optimizing the system’s output performance. Through MATLAB simulations, we demonstrate the iterative process of parameter optimization and validate the algorithm's efficacy in managing the DC-DC Buck Converter. The results highlight the enhanced performance achieved with the optimized parameters, providing a viable solution for effective control of DC-DC Buck Converter Systems.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Anatomical, Ecological and Trichome Micro-Morphological Features of Two
           Marrubium L. Taxa (Lamiaceae)

    • Authors: Kamer Volkan KOÇAK; Nezahat KANDEMİR
      Abstract: The anatomical, ecological and trichome micro-morphological features of two taxa (Marrubium amasiensis and Marrubium parviflorum subsp. parviflorum) belonging to the genus Marrubium were determined and these features were compared. M. amasiensis is endemic and is distributed only around Amasya in Türkiye. In anatomical examinations, cross sections were taken from the root, stem, petiole, leaves and surface sections were taken from stem, petiole, and the lower and upper surfaces of the leaves. When the anatomical findings were examined, multi-layered lamellar collenchyma layer was encountered at the corners of the stem. The studied taxa have equifacial leaves in terms of mesophyll structure. Stomata of M. amasiensis are anomocytic and rarely anisocytic type, while stomata of M. parviflorum subsp. parviflorum are anomocytic type. The margins of the adjacent cells of the stomata in both taxa are very undulate. Eglandular and glandular trichomes were seen on vegetative organs of the two taxa. The eglandular trichomes are stellate, dendroid, marrubioid and simple unicellular types, while glandular trichomes are capitate and peltate types. Dense stellate trichomes were found in the vegetative organs of the studied taxa. Since the head and stalk cell numbers of capitate trichomes showed variation, these trichomes were divided into subtypes. Three subtypes of capitate trichomes were found on the vegetative organs of M. parviflorum subsp. parviflorum, while four subtypes of capitate trichomes were found on the vegetative organs of M. amasiensis. Soil samples were taken during flowering periods of taxa, physical and chemical properties were determined. Some similarities and differences were detected in the anatomical, ecological and trichome micro-morphological features of the studied two taxa. It has been emphasized that these different features will be used as valuable taxonomic characters in distinguishing of the two taxa.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Production of Chemically Modified Shear Thickening Fluids and
           Investigation of Their Rheological Properties

    • Authors: Murat Yavuz SOLMAZ; Cenk YANEN, Celal KISTAK, Ercan AYDOĞMUŞ
      Abstract: In this study, the rheological properties of shear thickening fluid, which are generally used as single solid phase in the literature, were investigated by chemical material reinforcement. Considering that the unique shear thickening effect of STF is used in many areas such as increasing the impact resistance of fabrics and energy dissipation, this study aims to provide guidance for investigating what STFs can do with chemical bonds as well as physical bonding.Methylene diphenyl diisocyanate (MDI) was used in varying proportions for chemical reinforcement. When the rheological properties of the suspensions reinforced with MDI as a chemical additive were evaluated, the initial viscosity values increased as the MDI ratio increased, while the solidification behavior under shear was observed significantly in the sample with 2.5% MDI ratio with increasing shear ratio.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Radiative Transfer Equation Solution for Many Scattering Types

    • Authors: Dilek AYDIN; Halide KOKLU
      Abstract: The radiative transfer equation is a mathematical equation that describes the changes in the number of photons within a specified volume of a medium over time, taking into account phenomena such as scattering, absorption, and re-emission resulting from photon interactions with the medium. In this study, the radiative transfer equation is considered for a finite slab which anisotropic scattering in a homogeneous medium. The equation solution is done by Legendre polynomials for linear anisotropic, pure quadratic and Rayleigh scattering types. The numerical results are displayed in the tables up to the 13th iteration of the Legendre polynomials. Tables are obtained using different scattering coefficients and single scattering albedo values. The results contain a wide range of data obtained from the method of solving the Legendre polynomial of the radiative transfer equation. Thus, with this study, the effect of different scattering types on the solution of the radiative transfer equation has been demonstrated.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Effect of CaF2 Additions on the Yield of AZ63 Magnesium Chips during
           Remelting

    • Authors: Pınar YÖRÜK; Mertol GÖKELMA
      Abstract: Magnesium is one of the metals listed in European Union’s critical raw materials list. Primary production of magnesium is a high energy demanding process which raised the necessity of recycling the magnesium alloys in an efficient way. Remelting those scraps under a salt flux consist of chlorides (NaCl, KCl, and MgCl2) and fluorides (CaF2) are a common process however, different alloys might behave differently when it comes to salt-metal-metal oxide interactions. Furthermore, the condition of the salt flux such as dry-mixed or pre-melted (fused) affects the coagulation and metal yield. This work presents results on the effect of CaF2 concentration and pre-melting the salt flux on metal yield during remelting of chips. A yield up to 75% was observed in the case of remelting of chips under a fused salt flux with 5.5% CaF2 concentration.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Suggestions for Urban Transformation through Two Applications in Ankara,
           the Capital of Türkiye

    • Authors: Varol KOÇ
      Abstract: Cities resembling living organisms are dynamic places that constantly change, either positively or negatively. Urban transformation is a multifaceted process with economic, social, and cultural impacts, and it should trigger socio-economic change and transformation in a positive direction. This interaction between the city and urban transformation has also been integrated with relevant laws regulating the transformation. Urban transformation, which is a complex process in itself, draws from various related processes that have been ongoing since the past. The aim of the study is to examine the factors that play a role in the change and transformation of cities, their historical development, and legal regulations by analyzing the subject through two urban transformation examples in Ankara. In this context, Altındağ, which is the first region where gecekondu settlements began in Türkiye and the North Ankara Entrance Urban Transformation Projects, which marked the first urban transformation initiated by a law, were examined.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Numerical Modeling of the Movement of Self-Propelled Microorganisms in
           Newtonian Fluid

    • Authors: Hatice MERCAN; Tufan Tuna KÖSELER
      Abstract: The movement of micro-organisms is important both in understanding their biological behavior and in micro-robot design. The micro swimmer is often displaced by squirming motion at very low speeds in stationary fluid, a flow dominated by viscosity due to the low Reynolds number. The squirming movement differentiates the effect of the drag forces of the swimmer. Time-dependent periodic squirming motion for forward, reverse and neutral mode movements is modeled by ANSYS® software. The results are presented as streamlines, velocity isocurves, and wall shear force, vorticity, and drag coefficient variation at the swimmer wall for a full period after steady state is reached. It has been shown that the swimming efficiency of a squirming swimmer is dependent on both the Reynolds number and the swimmer's mode.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • PI-PD Controller Design Based on Weighted Geometric Center Method for Time
           Delay Active Suspension Systems

    • Authors: Abdullah TURAN; Hüseyin AGGÜMÜŞ, Mahmut DAŞKIN
      Abstract: In this study, a PI-PD controller was designed via weighted geometric center method (WGC) for a quarter vehicle model to suppress the vertical vibrations. The proposed design is based on finding the weighted geometric center of the area formed by the control parameters that make the system stable. The WGC method has two main stages. First, an area formed by the parameters of the PD controller (kf, kd) in the inner loop is obtained and the weighted geometric center of this area is calculated. Then, using these obtained parameters, the inner loop is reduced to a single block, and the parameters of the PI controller in the external loop (kp, ki) are calculated using the stability boundary curve as in the first step, and the weighted geometric center is calculated. The simulation results show that the PI-PD controller designed with the weighted geometric center method offers successful responses for the time delay quarter vehicle system.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • False Positives in Luminal Testing

    • Authors: Yakup GÜLEKÇİ; Fatma CAVUS YONAR
      Abstract: The blood sample is one of the most essential pieces of evidence that helps criminal experts in the elucidation of the crime. However, cleaning the blood found at the crime scene after the crime is committed makes it difficult to detect the crime. Therefore, experts have attached great importance to research on blood samples left at the crime scene. Although many test kits are used, especially in detecting erased blood, the luminol kit is widely used at crime scenes. In the luminol kit, the reaction takes place with the addition of hydrogen peroxide (H2O2). Since it is known that hydrogen peroxide can react with other substances containing Fe (II) ions that may be present in the environment during the reaction, it was aimed to carry out research to determine which substances luminol interferes with, especially those that may be found in a domestic crime scene in this study. In domestic crime scenes, there are limited substances that can replicate the distinct, enduring luminescence characteristic of a reaction between luminol and genuine bloodstains, while the uncharacteristic glow produced from many other surfaces is likely to be recognised with the naked eye by a good expert, experienced and knowledgeable in the field. In this regard, the prepared samples were treated with luminol in a dark environment, and the reactions occurring in the first seconds were recorded. The results obtained with this reagent are recommended to be supported by other blood test reagents or confirmatory tests, as there are substances that give false positive results with luminol reagents in the present study.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Effect of Different Step-Lap Joints on the Natural Frequencies of
           Different Adhesively Bonded Metallic Materials: A Numerical Study

    • Authors: Ali İhsan KAYA
      Abstract: Due to their many applications' benefits, adhesively bonded joints are widely utilized in nearly every industry, including space, marine, automotive, and aeronautics. Since unpredicted loadings may cause resonance in the structures, an accurate prediction of the bonded joints' dynamic characteristics is crucial. Therefore, in this study, modal analysis was performed on the two-, three-, four- and double-step adhesively bonded lap joints of Aluminum (Al), Copper (Cu), and Mild steel (Ms) materials with Epoxy Araldite adhesive. Ansys commercial program was utilized to analyze it numerically. The results showed that modeling the bonding region of single lap joints as two-, three-, and four-step adhesively bonded lap joints has no significant effect on the natural frequencies. This modeling has a minor incremental effect on the natural frequencies. However, Double-step lap joints were found to cause a considerable reduction in natural frequencies compared to not only single lap joints but also two-, three-, and four-step adhesively bonded lap joints. Double-step bonding caused a decrease of 8.82%, 8.57%, and 8.73% for Al-Al, Cu-Cu, and Ms-Ms. In general, in all models, the best increase or decrease in terms of natural frequencies was found to be Cu-Cu adhesively lap joints.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Valorisation of the Effect of Waste Aluminum Sawdust on Concrete:
           Durability Characteristics and Environmental Impacts

    • Authors: Tuba DEMİR; Bahar DEMİREL, Melek ÖZTÜRK
      Abstract: The aim of this study is to examine the effect of replacing waste aluminum sawdust (AS) with fine aggregate on the strength and durability properties of concrete. For this, concrete mixtures with a cement dosage of 400 kg/m3, water/cement (W/C) ratio of 0.40-0.50-0.60 were prepared. Aluminum sawdust obtained from Elazığ industrial site was added to the concrete mixtures by replacing 0%, 0.5% and 1% fine aggregate by volume. After curing in the curing pool for 28 days, the produced concrete samples were placed in the carbonation tank and exposed to the accelerated carbonation test in three different time periods as the 1st, 3rd and 7th days. Tests of compressive strength, splitting tensile strength, ultrasound transmission velocity, porosity and carbonation depth were performed on concrete samples before and after carbonation. The samples that were exposed to carbonation were compared with the samples that did not undergo carbonation. In addition, the microstructure of AS concrete was investigated using scanning electron microscopic images (SEM). In the microscopic images, larger cracks, openings and interfacial voids were observed in the concrete matrix with the addition of AS. However, due to the formation of ettringite in these gaps and cracks after carbonation, the cavities became smaller. As a result of the experiments, it was observed that the optimum W/C ratio was 40% and the AS amount was 0.5% in the use of AS in concrete. In addition, it was found that the carbonation effect improves the compressive and splitting tensile strength and increases the ultrasound transmission rate. Finally, life cycle assessment (LCA) was conducted to evaluate the environmental impacts of the prepared concrete samples. Considering the large amount of natural aggregate consumption, it is thought that the use of waste materials in concrete will provide environmental and economic benefits.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • An Integrated Overview of Blasting Damage Criteria for Engineering
           Structures

    • Authors: Davut YİLMAZ
      Abstract: Blasting applications are frequently used during the construction of engineering structures. In our country, damage assessment criteria created by reference to the Report of Investigations RI 8507 prepared by the United States Bureau of Mines (USBM) are used to control the impact of blast vibrations on existing structures or structures under construction. In this study, the structures in the database of that report of investigation and the points on which the damage criteria are based are examined. Moreover, in the light of the other studies carried out by different researchers about the blast damage criteria in engineering structures, the requirement of reevaluation of USBM damage criteria for reinforced concrete buildings, tunnels, pipelines and other engineering structures has been revealed.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • A Systematic Journey on the Naturally-Occurring Red Pigment Lycopene and
           Its Beneficial Effects on Health

    • Authors: Güney AKINOĞLU; Arzu ERDAL
      Abstract: Lycopene is a red pigment that belongs to the carotenoid group and occurs naturally in some vegetables and fruits, especially tomatoes and tomato-derived foods. The lycopene pigment is considered a powerful antioxidant and a carotenoid that has no pro-vitamin A activity. Lycopene has unique structural and chemical properties that can contribute to specific biological properties. Lycopene is thought to have a variety of beneficial effects in the prevention and treatment of various diseases such as diabetes, cardiovascular disease, cancer, skin and bone disorders, and neurological disorders. Although information is gradually accumulating in the literature on the bioavailability, tissue distribution, metabolism, excretion, and biological effects of lycopene in experimental animals and humans, further research is needed. This review summarizes the current state of knowledge on the properties, sources, absorption and bioavailability of lycopene and its potential role in human health.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
  • Application of Multi-Criteria Decision Making Methods for Menu Selection

    • Authors: Semih Latif İPEK; Dilek GÖKTÜRK
      Abstract: Nutritional information on menus can assist customers in making healthier eating choices. One technique being utilized to tackle the rise of overweight and obesity is the use of nutritional information on menus. Menu engineering strategies can be used to improve sales of generally healthier and higher margin items. For today's food and beverage companies, menu engineering has become essential. Companies must continually evaluate their menus in order to keep up with changing customer demands and the conditions of the competitive market. Menu engineering's core involves comparing the effectiveness of each menu. At this point, correct decision-making under numerous factors is thought to be a very challenging procedure. To evaluate alternatives according to many features, several Multi-Criteria Decision-Making (MCDM) approaches have been created. The main novelty of this paper is that four MCDM methods, including Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), Fuzzy TOPSIS, VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR), and Fuzzy VIKOR, are employed to evaluate menu options. Comparative analysis of MCDM methods is another contribution of this study. The process of evaluating and selecting healthier menu alternatives can become challenging and time-consuming. This study pointed out how crucial it is to conduct comparative analysis using various MCDA methods and to carefully determine the right ones when addressing the issue of selecting the best menu, taking into account the values of the criterion in fuzzy numbers.
      PubDate: Mon, 15 Jan 2024 00:00:00 +030
       
 
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