Çok katmalı yapıların bozulma analizi için yarı-analitik sonlu eleman modellenmesi

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2017Includes bibliographical references (leaves: 65-68)Text in English; Abstract: Turkish and EnglishUltrasonic guided waves are frequently employed for Non-destructive tests (NDT), and Structural Health Monitoring (SHM) applications in the industry. Several analytical and numerical approaches have been developed in order to investigate guided wave behavior on multilayered structures. In this thesis, guided waves were investigated using the Semi-Analytical Finite Element (SAFE) approach on planar (plate like) structures. The guided wave theory and dispersive behavior in bounded structure were presented for Lamb waves for isotropic elastic plate model first. The numerical method to solve the SAFE problem was developed using the Matlab 2014b in order to obtain dispersion curves. The curves were compared with the Disperse Software, which utilizes global matrix approach for analytical solution of the same problem. Good agreement was achieved on obtained dispersion curves. As a second part of this study, dispersion analysis was carried out in a multilayer plate model consisting of elastic and viscoelastic materials. The semi-analytical finite element method was solved by adapting the hysteretic damping model so that it can also be applied in a damped plate model. Phase velocity and attenuation dispersion curves were illustrated and the effect of the viscoelastic layer thickness is also discussed. The obtained attenuation dispersion curves in this damped plate configuration are examined for wave modes with low-attenuation. The dispersion curve results obtained using the SAFE method was also compared with the results of studies available in literature.Ultrasonik yönlendirilmiş dalgalar, endüstrideki Tahribatsız Muayene (NDT) ve Yapısal Sağlık İzleme (SHM) uygulamaları için sıklıkla kullanılır.Çok katmanlı yapılarda yönlendirilmiş dalga davranışını araştırmak için çeşitli analitik ve sayısal yaklaşımlar geliştirilmiştir. Bu tez çalışmasında, plaka benzeri yapılar üzerinde Yarı-Analitik Sonlu Elemanlar yaklaşımıyla yönlendirilmiş dalgalar araştırılmıştır.Öncelikle, sınırlı yapılarda ki yönlendirilmiş dalga teorisi ve dispersiyon (bozunma) davranışı, izotropik elastik plaka modeli üzerinde Lamb dalgaları göz önüne alınarak sunulmuştur. Dispersiyon eğrileri elde etmek için, SAFE probleminin sayısal çözümleri Matlab 2014b programı kullanılarak geliştirilmiştir.Dispersiyon eğrileri, aynı sorunun analitik çözümü için global matris yaklaşımını kullanan Disperse programı ile karşılaştırılmıştır.Bu karşılaştırma sonucunda, dispersiyon eğrileri üzerinde elde edilen değerlerde iyi bir mutabakat sağlandığı görülmüştür. Bu çalışmanın ikinci bir parçası olarak, elastik ve viskoelastik malzemelerden oluşan çok katmanlı plaka modelinde dispersiyon analizi yapılmıştır.Yarı-Analitik Sonlu elemanlar metodu, sönümlü plaka modelinde uygulanabilmesi için Histeretik sönümleme modeli adapte edilerek çözülmüştür.Faz hızı ve zayıflama dispersiyon eğrileri olarak gösterilmiş ve viskoelastik yapının etkileri tartışılmıştır.Bu sönümlü plaka konfigürasyonundan elde edilen zayıflama dispersiyon eğrileri düşük zayıflamaya sahip dalga modu seçimi için incelenmiştir. SAFE yöntemi kullanılarak elde edilen dispersiyon eğrisi sonuçları, literatürde mevcut olan çalışmaların sonuçları ile de karşılaştırılmıştır

Nutrient recovery and recycling from fishery waste and by-products

<p>HIGHLIGHTS:</p><ul><li>Fishery waste-based fertilisers perform equally to commercial synthetic fertilisers.</li><li>Fish sludge has a great potential but should be treated/refined before application.</li><li>Salinity and microplastics are potential critical parameters.</li><li>The choice of technology depends on the raw material and desired end-product.</li><li>Fish processing waste/wastewater/sludge has high protein and lipid contents.</li></ul><p>ABSTRACT</p><p>The circular bio-based economy offers great untapped potential for the food <a href="https://www.sciencedirect.com/topics/social-sciences/specific-industry">industry</a> as possible valuable products and energy can be recovered from food waste. This can promote more sustainable and resilient food systems in Europe in follow-up of the European Commission's Farm to Fork strategy and support the global transition to more sustainable agri-food systems with the common agricultural and fisheries policies. With its high nutrient content, waste and by-products originating from fish and seafood industry (including aquaculture) are one of the most promising candidates to produce alternative fertilising products which can play a crucial role to replace synthetic mineral fertilisers. Whereas several studies highlighted the opportunities to recover valuable compounds from fishery waste, study towards their potential for the production of fertilising products is still scarce. This study presents an extensive overview of the characteristics of fishery waste and by-products (i.e., fish processing waste, fish <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/sludge">sludge</a>, seafood waste/by-products), the state-of-the-art nutrient recovery <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/science-and-technology">technologies</a> and recovered nutrients as fertilising products from these waste streams. The European Commission has already adopted a revised Fertilising Products Regulation (EU) 2019/1009 providing opportunities for fertilising products from various bio-based origins. In frame of this opportunity, we address the quality and safety aspects of the fishery waste-derived fertilising products under these criteria and highlight possible obstacles on their way to the market in the future. Considering its high nutrient content and vast abundance, fish sludge has a great potential but should be treated/refined before being applied to soil. In addition to the parameters currently regulated, it is crucial to consider the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/salinity">salinity</a> levels of such fertilising products as well as the possible presence of other micropollutants especially <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/microplastics">microplastics</a> to warrant their safe use in agriculture. The agronomic performance of fishery waste-derived fertilisers is also compiled and reported in the last section of this review paper, which in most cases perform equally to that of conventional synthetic fertilisers.</p&gt

Targeted Bio-Based Volatile Fatty Acid Production from Waste Streams through Anaerobic Fermentation: Link between Process Parameters and Operating Scale

Anaerobic processes are proven to have much more environmental and economic benefits than conventional aerobic treatment systems, offering sustainable energy and valuable biochemicals. In recent years, bio-based volatile fatty acid (VFA) production has come into prominence as more value is derived before ending up with other final products. This paper presents a critical review of the research studies on bio-based VFA production from different waste streams (i.e., industrial sludge/waste, organic fraction of municipal solid waste/food waste, municipal wastewater/sludge, combined streams) through anaerobic fermentation. Fundamentals and decisive process parameters (i.e., pH, temperature, retention time, organic loading rate) are reviewed, and their correlations with VFA yields are critically discussed based on 178 cases (156 lab- and 22 pilot-scale). The picture we provided clearly demonstrates that process parameters should be clearly defined and optimized according to the type of waste streams which may have a significant impact on downstream processes in most cases

Ted Ankara Koleji Geleneksel Kuru Fasulye Günü’nün tarihi

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2015.This work is a student project of the The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.by Özer, Abdürrahim

Lessons learnt from different inoculation strategies for pilot-scale start-up of partial nitritation for landfill leachate treatment

Conventional biological processes are not enough to achieve desired removal efficiencies from N-rich waste streams such as landfill leachate. In this aspect, start-up phase of a sequencing batch reactor was monitored that treated landfill leachate through a nitritation (LPN) process. The reactor was inoculated from two different sources with distinctive microbial compositions. The acclimatized sludge, taken from a leachate intermittent aeration reactor, failed to establish nitritation but instead developed a nitrification process initially (N-NO3 > 500 mg/l and N-NO2 almost null) and showed no biological activity afterwards. The latter non-acclimatized sludge taken from a conventional activated sludge (CAS) reactor achieved N-NH4 removal up to 96%. Although the nitrite oxidizing genus Nitrospira was abundant in the CAS, it was not further detected in the LPN system. Moreover, the enrichment of ammonia oxidizing genus Nitrosomonas in the LPN was consistent with the establishment of an efficient nitritation process. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)