IYTE GCRIS Database (Izmir Institute of Technology)
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Kinematic Design of a Novel Finger Exoskeleton Mechanism for Rehabilitation Exercises
No full textThe paper presents the kinematic design of a novel low-cost two degree-of-freedom finger exoskeleton mechanism to be used for rehabilitation exercises for post-stroke or injured patients. The first degree-of freedom is for the flexion/extension of metacarpophalangeal joint and is achieved via a planar 4-bar loop. The second degree-of-freedom is for the simultaneous flexion/extension of distal/proximal interphalangeal joints and is achieved via an over-constrained double-spherical 6-bar linkage, where 3 of the links are the phalanges of the finger and 2 of the joints are finger joints themselves. So, the number of extra links are less compared to other designs in the literature. The motion of an index finger is recorded via image processing. The four-bar mechanism part is designed for optimum transmission angle characteristics. The formulation and application of the kinematic synthesis of the 6-bar linkage is presented. The design is verified via a prototype
Microstructural Evolution During Homogenization Heat Treatment of Aa 6063 Alloy in Batch and Continuous Furnaces
No full textHomogenization heat treatment after casting is performed to eliminate the dendritic segregation and coarse eutectic intermetallic phases since they reduce the fracture toughness of aluminium alloys. By the homogenization treatment, ss-AlFeSi can be converted to more spherical alpha-AlFeSi particles. The ss -> a transition is crucial because the ss-AlFeSi particles cause a number of surface defects and limit the extrudability. Also, the rate of cooling in the homogenization furnace is one of the critical influencing factors on the size of the Mg2Si precipitates which affect the mechanical properties positively. In this study, billets of AA 6063 from the same cast were put through homogenization heat treatment by using batch-type and continuous furnaces. The solution, quenching, and aging heat treatment were applied to each sample. Microstructural characterization by SEM and the hardness test were conducted to understand the effects of the furnace type on the mechanical properties of aged AA 6063 aluminium
Simultaneous Topology Design and Optimization of Pde Constrained Processes Based on Mixed Integer Formulations
No full textSimultaneous topological design and optimization of complex processes that are described by partial differential equations is a challenging but promising research area. Widely adopted nested and sequential approaches are mostly applicable based on heuristic solutions, hindering the theoretical improvement potential due to decentralized decision-making in subsequent stages with a significant number of trial-and-error procedures. This study introduces a mixed integer formulation addressing the governing equations and case-dependent topological constraints at each discretization point, enabling solutions through rigorous solvers under process-related constraints and objectives. Nonlinear expressions in the formulations are further tailored using piecewise linear approximations, still representing the major nonlinear trends through a mixed-integer linear nature to favor global optimality and benefit from computational advancements, when needed. Heat and Stokes flow problems are used as case studies to demonstrate the applicability of the methodology. © 2024 Elsevier B.V
Recent Developments Shaping the Future of Antimicrobial Edible Food Packaging: a Review
No full textThis article aimed at reviewing recent developments shaping the future of antimicrobial edible food packaging. The main issues discussed in the article are (i) factors (e.g. waste valorisation, sustainability, health and environmental concerns, religious concerns, etc.) causing emerging of alternative hydrocolloids extracted from farming/processing wastes of plants, animals, fungi, insects, snails, etc. as antimicrobial edible packaging material; (ii) emerging methods of manufacturing antimicrobial packaging (e.g. extruded and co-extruded antimicrobial casings, antimicrobial electrospun mats, and electrosprayed films, coatings and particles); (iii) emerging concepts in using natural antimicrobials in edible packaging such as using narrow- or broad-spectrum antimicrobials, synergetic mixtures, and controlled release strategies based on nanoencapsulation (e.g. Pickering emulsions, nanoemulsions, inclusion complexes, solid lipid nanoparticles and nanostructured lipid carriers). This review helps discovering the future of active edible packaging that is expected to play a central role in improving food safety and quality, human health and environmentally friendly practices. Factors shaping the future of antimicrobial edible packaging. imag
Calcium Indicators With Fluorescence Lifetime-Based Signal Readout: a Structure-Function Study
No full textThe calcium cation is a crucial signaling molecule involved in numerous cellular pathways. Beyond its role as a messenger or modulator in intracellular cascades, calcium's function in excitable cells, including nerve impulse transmission, is remarkable. The central role of calcium in nervous activity has driven the rapid development of fluorescent techniques for monitoring this cation in living cells. Specifically, genetically encoded calcium indicators (GECIs) are the most in-demand molecular tools in their class. In this work, we address two issues of calcium imaging by designing indicators based on the successful GCaMP6 backbone and the fluorescent protein BrUSLEE. The first indicator variant (GCaMP6s-BrUS), with a reduced, calcium-insensitive fluorescence lifetime, has potential in monitoring calcium dynamics with a high temporal resolution in combination with advanced microscopy techniques, such as light beads microscopy, where the fluorescence lifetime limits acquisition speed. Conversely, the second variant (GCaMP6s-BrUS-145), with a flexible, calcium-sensitive fluorescence lifetime, is relevant for static measurements, particularly for determining absolute calcium concentration values using fluorescence lifetime imaging microscopy (FLIM). To identify the structural determinants of calcium sensitivity in these indicator variants, we determine their spatial structures. A comparative structural analysis allowed the optimization of the GCaMP6s-BrUS construct, resulting in an indicator variant combining calcium-sensitive behavior in the time domain and enhanced molecular brightness. Our data may serve as a starting point for further engineering efforts towards improved GECI variants with fine-tuned fluorescence lifetimes
Evaluation of Heritage Characteristics and Conservation Problems of Bomonti Brewery
No full textThe Bomonti Brewery, established in the early 1900s in the Liman Arkası District, is an industrial site that has changed over time. It consists of several buildings around a central courtyard, reflecting the area's industrial history. This complex is a significant industrial heritage site that contributes to the distinct character of the Alsancak Liman Arkası District. However, shifts in urban planning, technology, and the privatization of Tekel have led to the cessation of industrial activities at the site. The property has been sold and is undergoing urban redevelopment. This study aims to analyze the conservation values and problems of the Bomonti Brewery and to assess the conservation and planning decisions made for it. The evaluation also includes the Liman Arkası District, of which the complex is a part. To achieve this goal, all historical archives related to the complex and subsequent decisions and relevant literature have been reviewed. Site surveys conducted at various times have assessed the current condition of the complex, including its built-up and open spaces. This study has revealed that the industrial complex holds significant documentary, historical, socio-cultural, architectural, economic, scientific, memory, and integrity values. However, its economic value has been prioritized due to its location, leading to planning decisions focused on profitability rather than comprehensive conservation. Out of the 46 buildings in the complex, only nine have been preserved, with the rest demolished. This has compromised the complex's integrity and changed the skyline of the Alsancak Liman Arkası District with the construction of new high-rise buildings.Bomonti Bira Fabrikası, Alsancak Liman Arkası Bölgesi'nde 20.yy'ın ilk çeyreğinde inşa edilmiş bir endüstri kompleksidir. Ana üretim binalarını çevreleyen avlu ile birlikte yıllar içinde ek işlevler kazanmış farklı yapıları içeren bu kompleks, Alsancak Liman Arkası Bölgesinin özgün karakterini belirleyen önemli endüstri miras alanlarındandır. Ancak seneler içerisinde değişen kentleşme pratiği, teknoloji ve Tekel'in özelleştirilmesi sonucunda endüstri kompleksinin faaliyetine son verilmiş; yerleşke arazisi satılarak alan dönüşüm süreci içine girmiştir. Bu çalışmanın amacı; Bomonti Bira Fabrikası Yerleşkesinin koruma değerlerini ve sorunlarını analiz ederek yerleşkeye yönelik alınan koruma ve planlama kararlarının değerlendirilmesidir. Yerleşkenin parçası olduğu Alsancak Liman Arkası Bölgesi de bu değerlendirmenin parçasıdır. Bu amaç doğrultusunda yerleşkenin tarihine ve sonrasında alınan kararlara ışık tutacak bütün arşivler taranmış ve ilgili literatür değerlendirilmiştir. Farklı tarihlerde yapılan alan çalışmaları ile yerleşkenin ve onu oluşturan yapı ve açık alanların günümüz durumu tespit edilmiştir. Bu çalışma ve tespitler, endüstri kompleksinin belgesel, tarihi, sosyo-kültürel, mimari, ekonomik, bilimsel, bellek ve bütünsellik değerlerine sahip olduğunu göstermiştir. Ancak konumu itibariyle yerleşkenin sahip olduğu ekonomik değerin öne çıktığı, buna bağlı olarak rant gözeten planlama kararları alındığı ve yerleşkenin bütüncül olarak korunamadığı belirlenmiştir. Endüstri kompleksini oluşturan 46 adet yapıdan yalnızca dokuzu korunmuş, geri kalan tüm yapılar yıkılmıştır. Endüstri kompleksinin bütünlüğü bozularak ve yerleşke içinde yüksek katlı yeni yapılara onay verilerek Alsancak Liman Arkası Bölgesi'nin silüeti değişikliğe uğratılmıştır
High Skid-Resistant Pavements: the Effect of Gritting Parameters
No full textTurkey's Highway Technical Specification (HTS) necessitates gritting of pavement surface courses for the regions where the high-polishing resistant aggregate (PSV >= 50) is lacking or hard to reach. The gritting is defined as the spreading of 1-3 mm magmatic origin aggregates with the rate of 1.5-2 kg/m2 to the pavement surface after the roller's first pass. This study investigates the effect of gritting construction parameters (aggregate type, size, amount, and time of spreading) on pavement surface texture and skid resistance by monitoring the performance of nine test sections over more than three years under real traffic and environmental conditions. Considering the field observations, reduction in skid resistance with respect to traffic, in terms of equivalent standard axle load, is modeled for all test sections, and their service life is calculated. The results show that test sections gritted with the slag-origin aggregates perform better and yield nearly twice the service life of the one specified in the HTS. Accordingly, using slags in pavement gritting would provide safer and more sustainable highways
Development of Chrono-Spectral Gold Nanoparticle Growth Based Plasmonic Biosensor Platform
No full textPlasmonic sensor platforms are designed for rapid, label-free, and real-time detection and they excel as the next generation biosensors. However, current methods such as Surface Plasmon Resonance require expertise and well-equipped laboratory facilities. Simpler methods such as Localized Surface Plasmon Resonance (LSPR) overcome those limitations, though they lack sensitivity. Hence, sensitivity enhancement plays a crucial role in the future of plasmonic sensor platforms. Herein, a refractive index (RI) sensitivity enhancement methodology is reported utilizing growth of gold nanoparticles (GNPs) on solid support and it is backed up with artificial neural network (ANN) analysis. Sensor platform fabrication was initiated with GNP immobilization onto solid support; immobilized GNPs were then used as seeds for chrono-spectral growth, which was carried out using NH2OH at varied incubation times. The response to RI change of the platform was investigated with varied concentrations of sucrose and ethanol. The detection of bacteria E.coli BL21 was carried out for validation as a model microorganism and results showed that detection was possible at 102 CFU/ml. The data acquired by spectrophotometric measurements were analyzed by ANN and bacteria classification with percentage error rates near 0% was achieved. The proposed LSPR-based, label-free sensor application proved that the developed methodology promises utile sensitivity enhancement potential for similar sensor platforms. © 2024 The Author(s
A Computational Fluid Dynamics Investigation of Motion Mitigation on a Floating Object Containing Tuned Liquid Column Damper
No full textNet sıfır emisyon enerji sistemlerine yönelik küresel dönüşüm, sürdürülebilir gelişmelere ve yenilenebilir enerji alternatiflerine olan ilgiyi artırmış, rüzgâr bu bağlamda ön plana çıkmıştır. Ancak, geleneksel yöntemler derin su bölgelerindeki rüzgâr kaynaklarına erişimde zorlanmaktadır. Denizüstü Yüzer Rüzgar Türbinleri (YRT), bu engeli aşarak daha önce erişilemeyen derin su sahalarından rüzgâr enerjisi elde etmeyi mümkün kılmıştır. YRT'lerin ömrünü uzatmak için istenmeyen yük ve hareketlerin en aza indirilmesi kritik öneme sahiptir. Bu proje, OpenFOAM kullanarak YRT'lerin yüksek doğruluklu ve entegre bir simülasyon metodolojisini araştırmaktadır. Dalga üretimi ve sönümlemesi için 'sönümleme bölgesi' yöntemini kullanan waves2Foam aracı (Jacobsen vd. 2012) kullanılmış ve demirleme kuvvetleri yarı sabit katener modeli ile hesaplanmıştır. Çok fazlı simülasyon, dinamik ağ teknikleri entegre edilen waveDyMFoam çözücüsü ile gerçekleştirilmiştir. Akışkan-Yapı Etkileşimi (AYE) bağlantısı, PIMPLE metoduna dayalı, seri alt yineleme stratejisi ile sağlanmıştır. Metodoloji, Ayarlanmış Sıvı Kolon Sönümleyici (ASKS) uygulaması ile adım adım geliştirilmiş ve mevcut çalışmalarla doğrulanmıştır. Ardından, bir Dalga Enerji Dönüştürücüsü (DED) üzerinde serbest bozunma analizi yapılmış ve ASKS'nin farklı kütle oranları altında sönümleme performansı doğrulanmıştır. Serbest bozunma koşullarında %4 kütle oranlı ASKS uygulaması ile hareket azaltımı %47,80, düzenli dalga koşullarında ise %37,01 olarak elde edilmiştir. Bu metodoloji, ASKS ve Ayarlanmış Sıvı Çok Kolonlu Damper (ASÇKS) uygulamalarının dalga koşulları altında yüzer nesneler üzerindeki sönümleme performansını başarıyla göstermekte olup, YRT modellemesi için ASKS'nin güvenilir bir teknik olduğunu kanıtlamaktadır.The global shift towards net-zero emission energy systems has heightened interest in sustainable developments and renewable energy alternatives, with wind emerging as a key resource. However, conventional methods struggle to access wind resources in deepwater areas. Floating Offshore Wind Turbines (FOWTs) have overcome this limitation, enabling the harnessing of wind energy at previously inaccessible deep-water sites. To extend the operational life of FOWTs, it is crucial to minimize undesirable loads and motions. This project investigates a methodology for high-fidelity, coupled simulation of FOWTs in OpenFOAM. The waves2Foam tool by (Jacobsen et al. 2012), utilizing the relaxation zone method, is employed for wave generation and absorption, while mooring restraints are computed using a quasi-steady catenary model. The multiphase simulation employs the waveDyMFoam solver, modified by the interFoam solver, incorporating dynamic mesh techniques. Fluid-structure interaction (FSI) coupling is implemented through a PIMPLE-based, serial sub-iterating strategy. The methodology was developed incrementally, beginning with the Tuned Liquid Column Damper (TLCD) implementation, validated against existing studies. Free-decay analysis was then conducted on a wave energy converter (WEC), confirming the damping performance of a TLCD applied with varying mass ratios. Eventually, motion mitigation was obtained in free decay condition by 47.80% with a 4% mass ratio TLCD application and 37.01% achieved under regular wave conditions. The methodology successfully demonstrates the damping performance of TLCD and Tuned Liquid Multi Column Damper (TLMCD) applications on floating objects under wave conditions, making it a reliable technique for TLMCDs in FOWT modeling
Lacoo3 Is a Promising Catalyst for the Dry Reforming of Benzene Used as a Surrogate of Biomass Tar
No full textTar build-up is one of the bottlenecks of biomass gasification processes. Dry reforming of tar is an alternative solution if the oxygen chemical potential on the catalyst surface is at a sufficient level. For this purpose, an oxygen-donor perovskite, , was used as a catalyst for the dry reforming of tar. To circumvent the complexity of the tar and its constituents, the benzene molecule was chosen as a model compound. Dry reforming of benzene vapor on the catalyst was investigated at temperatures of 600, 700, and 800 °C; at ratios of 3, 6, and 12; and at space velocities of 14,000 and 28,000 h–1. The conventional Ni(15 wt.%)/ catalyst was also used as a reference material to determine the relative activity of the catalyst. Different characterization techniques such as X-ray diffraction, adsorption-desorption, temperature-programmed reduction, and oxidation were used to determine the physicochemical characteristics of the catalysts. The findings demonstrated that the catalyst has higher conversion, higher and CO yields, and better stability than the Ni(15 wt.%)/γ- catalyst. The improvement in activity was attributed to the strong capacity of for oxygen exchange. The transfer of lattice oxygen from the surface of the catalyst facilitates the oxidation of carbon and other surface species and leads to higher conversion and yields