IYTE GCRIS Database (Izmir Institute of Technology)
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Comprehensive Analysis of Botanical Origin and Amino Acid Composition of Bee Pollen Samples From Various Regions of Turkey
No full textThis study aimed to investigate the botanical diversity in bee pollen and amino acid composition of Turkish bee pollen samples collected from different regions. The monofloral bee pollen samples belonged to three different plant families: Asteraceae, Fabaceae, and Ranunculaceae. Additionally, Agean, Central Anatolian, Black Sea, and Marmara Regions have monofloral bee pollen samples with higher than 85% pollen frequency. The free amino acid (FAA) composition and content of the bee pollen samples were analyzed, with the essential amino acids comprising 13.13-18.28% of the total amino acid content. The Central Anatolian region displayed the highest ratio of essential amino acids, and the Aegean region exhibited a more diverse profile of FAA. Principal Component Analysis was performed to evaluate the variation in the data, with the eigenvalues of the two factors explaining 68.58% of the total variability. Moreover, cluster analysis revealed distinct dendrograms based on palynological characteristics and FAA composition
Homogenization of 3d Laminated Micro-Structures Including Bending Effects
No full textIn this paper, a homogenization method which captures intrinsic size effect associated with fiber diameter is revisited and adapted for three-dimensional laminated micro -structures. Based on a unit-cell composed of matrix and reinforcement layers, enhanced deformation gradients varying through the thickness, are introduced with the aid of an additional kinematic variable reflecting the difference between the homogenized and constituent level deformation gradients. In the current work, as opposed to the original formulation, higher order terms are preserved for both phases and therefore bending stiffness of the matrix phase can be taken into account as well. The formulation is implemented within the commercial finite element solver Abaqus through user element (UEL) subroutine considering a finite strain hyperelastic response for the reinforcement layers and a von Mises type hyper-elastoplastic one for the matrix phase. Explicitly discretized unit-cells with varying reinforcement phase fraction, layer inclination angle and layer thicknesses are used as references to assess the predictive capabilities of the homogenized model and the significance of bending stiffness of the phases. Similarly, explicitly discretized model of a beam type structure with a crossed lamellar micro -structure is used to evaluate the performance of the homogenized model under more general, non-periodic boundary conditions. The findings of both cases support the effectiveness of the homogenized model
Effects of Fiber Discontinuity in Fiber Reinforced Polymer Matrix Composites
No full textBu tez, cam elyaf takviyeli kompozit plakaların mekanik davranışları üzerindeki yapısal süreksizliklerin etkisini araştırmaktadır. Bu süreksizlikler, kompozit mikro yapısındaki geometrik kısıtlamalar nedeniyle katmanlar arası (inter-ply) ve katman içi (intra-ply) olarak sınıflandırılmıştır. Süreksizlikler kürleme öncesi ilave edilmiştir. İlk olarak, malzeme özellikleri kupon seviyesinde testlerle belirlenmiştir. Daha sonra, bilgisayarlı sayısal kontrol kesimi ve manuel uygulama ile katman içi süreksizlikler oluşturularak iki tam ölçekli kompozit numune üretilmiştir. Bu numunelerin mekanik özellikleri, servo-hidrolik aktüatörler kullanılarak üç nokta eğme testi ile değerlendirilmiştir. Deneysel test sonuçları, kesitsel fiber hacim oranı değerlendirilerek CAE analiz tahminleriyle karşılaştırılmış ve yerel süreksizliklerin mikroskopik analizi ile desteklenmiştir. Çalışma, yer değiştirme bölgelerinin reçine açısından zengin alanlara yol açtığını ve ekzotermik kürleme sürecinin reçinenin rengini şeffaftan sarıya dönüştürdüğünü, bunun da mekanik dayanıklılığı azalttığını ortaya koymuştur. Ayrıca, fiber süreksizlikleri ve reçine boşlukları, cam elyaf takviyeli polimer (GFRP) kompozit yaprak yayların yapısal bütünlüğünü olumsuz etkilemektedir. Üretim sürecindeki düzensizlikler, malzeme dayanıklılığını ve boşluk doldurma kapasitesini etkilemektedir. Isı transferi ile ilgili sorunların ele alınması, reçine boşluklarını ve ısı kaynaklı çatlakları azaltmak için önemlidir. Bulgular, iç yapısal kusurlar ve reçine boşlukları arasındaki ilişkiyi anlamanın, kiriş tasarımı ve üretim süreçlerini önemli ölçüde iyileştirebileceğini önermektedir. Bu çalışma, mühendislik uygulamalarında kompozit malzemelerin yapısal performansını ve güvenilirliğini optimize etmek için kritik bilgiler sunmaktadır.This dissertation examines how structural discontinuities affect the mechanical properties of composite beams reinforced with glass fibers. The study explicitly classifies these discontinuities as inter-ply or intra-ply based on discontinuity types within the composite layers. Discontinuities were introduced as pre-curing. The mechanical properties of these samples were evaluated using servo-hydraulic actuators in three-point bending quasi-static tests. The experimental results were compared to the predictions of CAE analysis by assessing the sectional fiber volume fraction and further complemented with microscopic analysis of local discontinuities. The study found that areas of dislocation lead to zones with a high concentration of resin, and the exothermic curing process causes increased temperatures. As a result, the resin changes color from clear to yellow, indicating decreased mechanical durability. Fiber discontinuities and resin gaps weaken the structural integrity of glass fiberreinforced polymer (GFRP) composite leaf springs. Irregularities in manufacturing, whether between layers or within a single layer, can impact the durability of the material and its ability to fill gaps. The findings highlight the significance of material composition, structural integrity, and comprehension of failure mechanisms in the design and production of composite beams. It is essential to address heat transfer concerns to reduce resin gaps and prevent fractures caused by heat. The results indicate that understanding the relationship between internal structural flaws and gaps in the resin can greatly improve the design and production of beams. This study offers crucial insights for enhancing composite materials' structural performance and dependability in engineering applications
Torque-Current Relationship of an Mr Brake for Its Open-Loop Control
No full textActive and semiactive actuators have been widely preferred for designing an actuation system for kinesthetic-type haptic devices. Among them, magnetorheological fluid-based brakes (MR brakes) offer potent properties, such as high torque/inertia ratio and less power consumption. However, one of the most critical issues to be resolved is their hysteresis behavior. Various methods for modeling the input/output relationship with hysteresis behavior exist. However, hysteresis compensation approaches, i.e., torque-current hysteresis model, are not widely studied for MR Brakes. Therefore, a hysteresis compensation model approach to account for the nonlinear behavior of MR Brake is proposed, and the model is experimentally validated in this article. The model consists of multiple splines and an algorithm that uses these splines in hysteresis compensation. Being relatively simple and easily implementable are the distinguished features of the presented model since an optimization method is not required. Furthermore, the performance of the proposed method is compared with two methods, torque-to-current mapping and inverse Prandtl-Ishlinskii method. The obtained experimental results are investigated with three performance metrics. Finally, the effect of the operational speed on the performance of the hysteresis compensation model is also discussed
Invasion/Chemotaxis- and Extravasation-Chip Models for Breast Cancer Bone Metastasis
No full textBone is one of the most frequently targeted organs in metastatic cancers including the breast. Breast cancer bone metastasis often results in devastating outcomes as limited treatment options are currently available. Therefore, innovative methods are needed to provide earlier detection and thus better treatment and prognosis. Here, we present a new approach to model bone-like microenvironments to detect invasion and extravasation of breast cancer cells using invasion/chemotaxis (IC-) and extravasation (EX-) chips, respectively. Our results show that the behaviors of MDA-MB-231 breast cancer cells on IC- and EX-chip models correlate with their in vivo metastatic potential. Our culture model constitutes cell lines representing osteoblasts, bone marrow stromal cells, and monocytes embedded in three-dimensional (3D) collagen I-based extracellular matrices of varying composition and stiffness. We show that collagen I offers a better bone-like environment for bone cells and matrix composition and stiffness regulate the invasion of breast cancer cells. Using in situ contactless rheological measurements under cell culture conditions, we show that the presence of cells increased the stiffness values of the matrices up to 1200 Pa when monitored for five days. This suggests that the cellular composition has a significant effect on regulating matrix mechanical properties, which in turn contribute to the invasiveness. The platforms we present here enable the investigation of the underlying molecular mechanisms in breast cancer bone metastasis and provide the groundwork of developing preclinical tools for the prediction of bone metastasis risk
Analysis, Design, Test, and Devops in Microservice-Based Software Architectures: Results From Pakistan
No full textIn today's software industry, Microservice-based Software Architecture (MSSA) has been a common practice and has been adopted by many companies. MSSA differs from traditional object-oriented architecture in several ways. The architecture moved away from being data-driven and evolved into a behavior-oriented structure. The usage of a single database is replaced by the structures in which each microservice is developed independently and has its own database. Therefore, adaptation demands software organizations to transform their culture. However, there is no de facto method for analyzing, designing, and testing systems for these architectures, similar to object-oriented analysis and design practices. This study aimed to understand how Pakistani software organizations undertake analysis, design, test, and DevOps processes in software projects adopting the MSSA paradigm. To achieve this goal, we surveyed 49 participants from various agile organizations in Pakistan, encompassing different roles and domains. The results reveal that Pakistani software organizations continue using familiar object-oriented analysis and design approaches. However, they have already started exploring event-oriented analysis and design methods for MSSA projects
Edge Deletion Based Subgraph Hiding
No full textExtracting subgraphs from graph data is a challenging and important subgraph mining task since they reveal valuable insights in many domains. However, in the data sharing scenario, some of the subgraphs might be considered as sensitive by the data owner and require hiding before publishing the data. Therefore, subgraph hiding is applied to the data so that when subgraph mining algorithms, such as frequent subgraph mining, subgraph counting, or subgraph matching, are executed on this published data, sensitive subgraphs will not appear. While protecting the privacy of the sensitive subgraphs through hiding, the side effects should be kept at a minimum. In this paper, we address the problem of hiding sensitive subgraphs on graph data and propose an Edge deletion-based heuristic (EDH) algorithm. We evaluate our algorithm using three graph datasets and compare the results with the previous vertex masking heuristic algorithms in terms of execution time and side effects in the context of frequent subgraph hiding. The experimental results demonstrate that the EDH is competitive concerning execution time and outperforms the existing masking heuristic algorithms in terms of side effects by reducing information loss of non-sensitive patterns significantly and not creating fake patterns. © 2024 World Scientific and Engineering Academy and Society. All rights reserved
A Safe Fiber-Optic-Sensor-Assisted Industrial Microwave-Heating System
No full textIndustrial microwave-heating systems are pivotal in various sectors, including food processing and materials manufacturing, where precise temperature control and safety are critical. Conventional systems often struggle with uneven heat distribution and high fire risks due to the intrinsic properties of microwave heating. In this work, a fiber-optic-sensor-assisted monitoring system is presented to tackle the pressing challenges associated with uneven heating and fire hazards in industrial microwave systems. The core innovation lies in the development of a sophisticated fiber-optic 2D temperature distribution sensor and a dedicated fire detector, both designed to significantly mitigate risks and optimize the heating process. Experimental results set the stage for future innovations that could transform the landscape of industrial heating technologies toward better process quality
Patient-Specific Finite Element Analysis for Assessing Hip Fracture Risk in Aging Populations
No full textThe femur is one of the most important bone in the human body, as it supports the body's weight and helps with movement. The aging global population presents a significant challenge, leading to an increasing demand for artificial joints, particularly in knee and hip replacements, which are among the most prevalent surgical procedures worldwide. This study focuses on hip fractures, a common consequence of osteoporotic fractures in the elderly population. To accurately predict individual bone properties and assess fracture risk, patient-specific finite element models (FEM) were developed using CT data from healthy male individuals. The study employed ANSYS 2023 R2 software to estimate fracture loads under simulated single stance loading conditions, considering strain-based failure criteria. The FEM bone models underwent meticulous reconstruction, incorporating geometrical and mechanical properties crucial for fracture risk assessment. Results revealed an underestimation of the ultimate bearing capacity of bones, indicating potential fractures even during routine activities. The study explored variations in bone density, failure loads, and density/load ratios among different specimens, emphasizing the complexity of bone strength determination. Discussion of findings highlighted discrepancies between simulation results and previous studies, suggesting the need for optimization in modelling approaches. The strain-based yield criterion proved accurate in predicting fracture initiation but required adjustments for better load predictions. The study underscores the importance of refining density-elasticity relationships, investigating boundary conditions, and optimizing models through in vitro testing for enhanced clinical applicability in assessing hip fracture risk. In conclusion, this research contributes valuable insights into developing patient-specific FEM bone models for clinical hip fracture risk assessment, emphasizing the need for further refinement and optimization for accurate predictions and enhanced clinical utility
Modeling Cosmological Perturbations of Thermal Inflation
No full textWe consider a simple system consisting of matter, radiation and vacuum components to model the impact of thermal inflation on the evolution of primordial perturbations. The vacuum energy magnifies the primordial modes entering the horizon before its domination, making them potentially observable, and the resulting transfer function reflects the phase changes and energy contents. To determine the transfer function, we follow the curvature perturbation from well outside the horizon during radiation domination to well outside the horizon during vacuum domination and evaluate it on a constant radiation density hypersurface, as is appropriate for the case of thermal inflation. The shape of the transfer function is determined by the ratio of vacuum energy to radiation at matter-radiation equality, which we denote by upsilon , and has two characteristic scales, ka and kb , corresponding to the horizon sizes at matter radiation equality and the beginning of the inflation, respectively. If upsilon MUCH LESS-THAN1 , the Universe experiences radiation, matter and vacuum domination eras and the transfer function is flat for kMUCH LESS-THANkb , oscillates with amplitude 1/5 for kbMUCH LESS-THANkMUCH LESS-THANka and oscillates with amplitude 1 for k >> ka . For upsilon >> 1 , the matter domination era disappears, and the transfer function reduces to being flat for kMUCH LESS-THANkb and oscillating with amplitude 1 for k >> kb