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Design and development of a torsion-based series elastic actuator with nested encoders for a wearable exoskeleton robot
No full textThis paper presents the design of a high torque-to-mass ratio series elastic actuator (SEA) for wearable powered exoskeletons. Nonbackdrivable actuators are ideal for applications that require high torque. Commonly, active exoskeleton robots are powered by actuators that are nonbackdrivable. Due to the high gear ratio, the output mechanical impedance of these actuators is quiet high which renders their force/torque control challenging. To provide torque controllability a custom torsional spring has been produced and placed at the output side of the series elastic actuator. In addition, the measurement of the angular displacement of this elastic element is challenging in terms of mechanical design. To prevent this design challenge a double shaft mechanism was proposed. In this mechanism, the first shaft, which connects the spring and the spring encoder, goes through the second shaft, which is connected to the motor and the motor encoder. This way both encoders are placed on a the same side of the SEA. In addition to explaining this compact spring shaft mechanism, this article presents the results of the cascaded PID controller with a disturbance observer (DoB) applied on the actuator.TÜBİTA
Acoustics and heat transfer characteristics of piezoelectric driven central orifice synthetic jet actuators
No full textGrowth in computational capacity combined with a decrease in the size of digital devices has led to increasing demand for more active and efficient cooling of electronics. In this study, an experimental investigation into two different sizes of central orifice Synthetic Jet Actuators (SJAs) is conducted to evaluate their heat transfer as well as noise generation characteristics. Two SJAs (40 mm and 20 mm) are examined, covering a distinct span of frequencies ranging from low to medium (<5500 Hz) in regards to the effect of SJA size over performance. The SJAs’ disk deflection, structural frequency, and jet exit velocity were measured to fully characterize the jet performance. The maximum Nusselt number for the largest SJA was 3 times more than the smallest SJA, where the evaluation of stroke length suggests no effective synthetic jet formation for the smallest SJA. The noise from the SJAs was measured in an anechoic chamber using three microphones, Fast Fourier Transform (FFT) of the sound pressure levels provide contributions to different tones in the resulting noise. 1/3 Octave Constant Percentage Bandwidth (CPB) analysis was performed to identify the frequency bands making the largest contribution to the noise. The largest SJA showed the highest heat transfer at acceptable noise levels during the operation below resonance frequency.TÜBİTAK ; EVATEG center ; Arçelik Corporatio
Katılımcı mimarlığı değerlendime modeli: dayanışma mimarlığı sergisi grupları örneği
No full textThe relationship between participation and architecture has been discussed for more than fifty years, along with human-oriented design approaches. Scientists from the field of architecture and other related disciplines have been tackling the concept of participatory architecture and its various aspects through several methods and theories. This thesis aims to present a model by setting forth multiple dimensions of participatory architecture. The purpose of this model is to evaluate participatory architecture, making use of a multi-dimensional perspective to participatory architecture practices. Individuals need to have a certain level of say in the emergence of the place where they spend their daily lives, state their ideas and requests, and experience the space they use to take ownership of the area and establish a bond. It is an accepted fact that the user exists not as a subject but as an object within the architectural product produced in conventional architecture and construction processes. However, architectural figures, groups, and collectives also produce products applying alternative models contrary to these processes. Architectural forms that offer examples by adopting understandings that incorporate users through various tactics, methods and designs can be seen in different geographies. This thesis study focuses on the projects that incorporate users in processes through alternative architectural products. The thesis study model searches for the potentials, opportunities, and threats in participatory architecture. In this context, the theoretical and practical background of the literature research was carried out primarily to understand the concept of participation and its dimensions related to architecture. The inferences made here reveal the multiple dimensions of participatory architecture. These dimensions are levels and processes, players and participation techniques. The study addresses the applied processes conducted by the Solidarity Architecture Exhibition Groups (SAEx) that have compiled alternative architecture practices employed in Turkey in recent years. Conducted by quantitative techniques, the thesis uses a summative evaluation methodology. It builds a three-stage model for method of analysis. Participation ladder analysis (1), stakeholder typology analysis (2) and participatory techniques analysis (3) have helped interpret the architecture activities carried out with participants. In light of the evaluation, this thesis discusses the issue of participatory architecture using various observations made in the processes. This discussion describes a guiding method for participatory architecture. Data collected from primary and secondary sources are tested using a structured evaluation form to carry out the analysis. The structured evaluation form is a systematic examination that questions the existence of the specified parameters. The resulting findings provide information about the strengths and weaknesses of participatory architecture and its place in the Turkish world of architecture. The participant discusses architecture in the light of various inferences observed in the evaluation processes. This discussion describes a guiding participatory method of architecture. Chapter 1 provides detailed information on the problems, hypothesis, research questions, aims of the research, the scope of the research, and the methods used to conduct the research. Chapter 2 describes the concept of participation and its relations with architecture as a profession based on theoretical and practical studies. Chapter 3 describes the methodology of the study, the level and process relationship, players and participation methods described as multiple dimensions of participation are classified based on references from the literature. A new analysis model is introduced according to this classification. In line with the parameters determined by the three-stage analysis method, data collection criteria from primary and secondary sources related to the production of SAEx groups determined as case studies are specified within the scope of the study. Chapter 4 focuses on the data collected in 28 projects of the SAEx groups in line with the parameters determined in the previous chapter and various findings collected applying the three-stage analysis method. The results obtained are based on these findings. The last chapter discusses the relationship between participation and architecture, first in SAEx and then in Turkey and the global context, in the light of findings and results.Katılım ve mimarlık ilişkisi, insan odaklı tasarım yaklaşımları ile birlikte yarım asrı aşkın bir süredir tartışılmaktadır. Katılımcı mimarlık; mimarlık ve ilgili disiplinlerden bilim insanları tarafından çeşitli yöntem ve teoriler ile farklı boyutlarıyla ele alınmaktadır. Tez çalışması katılımcı mimarlığın çoklu boyutlarını tanımlayarak bir model ortaya koymayı hedefler. Bu model, katılımcı mimarlık pratiklerine belirli bakış açısı getirerek değerlendirme yapmayı amaçlamıştır. Bireyin, gündelik yaşantısını geçirdiği mekanın ortaya çıkış sürecinde belirli bir düzeyde söz sahibi olması, fikir ve talep beyan etmesi ve deneyimlemesi kullandığı mekanı sahiplenmesi ve bağ kurması açısından önemlidir. Alışılagelmiş mimarlık ve inşa süreçlerinde kullanıcının, özne olarak değil, üretilen mimarlık ürünü içerisinde nesne olarak var olduğu kabul edilmiş bir gerçekliktir. Ancak bu süreçlerin aksine alternatif modeller ile üretimler gerçekleştiren mimarlık figürleri, grupları ve kolektifleri de bulunmaktadır. Çeşitli taktik, yöntem ve kurgular ile kullanıcıyı dahil eden anlayışları benimseyerek örnekler veren mimarlık biçimleri farklı coğrafyalarda belirir. Tez çalışması alternatif mimarlık üretimleri ile katılımcıyı süreçlere dahil eden çalışmalara odaklanır. Ortaya koyduğu model ile katılımcı mimarlık süreçlerinin içinde barındırdığı potansiyelleri, imkanları ve tehditleri aramayı hedeflemiştir. Bu bağlamda öncelikle katılım kavramı ve mimarlık ile ilişkili boyutlarını anlamaya yönelik literatür araştırması yapılmış, teorik ve pratik arka planı okunmuştur. Buradan yapılan çıkarımlar ile katılımcı mimarlığın çoklu boyutları ortaya konmuş ve değerlendirme parametreleri belirlenmiştir. Bu boyutlar düzey and süreç ilişkisi, aktörler ve katılım teknikleridir. Çalışma, Türkiye’de son yıllarda yapılan alternatif mimarlık pratiklerini bir araya getiren Dayanışma Mimarlığı Sergisi gruplarının yürüttüğü uygulamalı süreçleri değerlendirme modelinde ele alır. Niceliksel yöntemler ile yürütülen çalışmada özetleyici bir değerlendirme metodolojisi kullanılmıştır. Üç aşamalı bir analiz yöntemi modeli oluşturur. Katılım düzey analizi (1), paydaş tipoloji analizi (2) ve katılım teknikleri analizi (3) ile süreçlerde katılımcılar ile yürütülen mimarlık faaliyetleri yorumlanmıştır. Analiz çalışmasını yapmak adına birincil ve ikincil kaynaklardan toplanan bilgiler, yapılandırılmış değerlendirme formu ile sınanır. Yapılandırılmış değerlendirme formu belirlenen parametrelerinin varlığını sorgulayan sistematik bir inceleme strüktürüdür. Ortaya çıkan bulgular, bizlere katılımcı mimarlığın güçlü ve zayıf yönleri ile Türkiye mimarlık ortamındaki yeri hakkında çeşitli bilgiler verir. Katılımcı mimarlık meselesini, değerlendirme ışığında, süreçlerde gözlemlenen çeşitli çıkarımlar ile tartışır. Bu tartışma yol gösterici bir katılımcı mimarlık yöntemi tarifler. Tez çalışmasının birinci bölümünde problem, hipotez, araştırma sorusu, kavramsal çerçevesi, tezin amacı, hedefi, kapsamı ve araştırma yöntemi ile ilgili açıklamalara yer verilmiştir. İkinci bölüm teorik ve pratik arka planda katılım kavramı ve mimarlık eylemi ile olan ilişkisini tarifler. Üçüncü bölümde çalışmanın metodolojisi tariflenmiştir. Katılımcılığın çoklu boyutları olarak tariflenen düzey ve süreç ilişkisi, aktörler ve katılım yöntemleri literatürden atıflar ile sınıflandırılmıştır. Bu sınıflandırmadan yeni bir analiz modeli ortaya konmuştur. Üç aşamalı analiz yöntemi ile belirlenen parametreler doğrultusunda çalışma kapsamında alan çalışması olarak belirlenen Dayanışma Mimarlığı Sergisi gruplarının üretimlerine ilişkin birincil ve ikincil kaynaklardan veri toplama kriterleri belirtilmiştir. Dördüncü bölümde ise bir önceki bölümde belirlenen parametreler doğrultusunda gruplara ait 28 projeden veriler toplanmış ve üç aşamalı analiz yöntemi ile çeşitli bulgular edinilmiştir. Bu bulgular ile sonuçlar elde edilmiştir. Son bölümde ise bulgular ve sonuçlar ışığında önce gruplar özelinde ve Türkiye ile küresel ölçekte katılım ve mimarlık ilişkisi tartışılmıştır
Sustainability challenges for the social-environmental systems across the Asian Drylands Belt
No full textThis paper synthesizes the contemporary challenges for the sustainability of the social-environmental system (SES) across a geographically, environmentally, and geopolitically diverse region - the Asian Drylands Belt (ADB). This region includes 18 political entities, covering 10.3% of global land area and 30% of total global drylands. At the present time, the ADB is confronted with a unique set of environmental and socioeconomic changes including water shortage-related environmental challenges and dramatic institutional changes since the collapse of the Union of Soviet Socialist Republics. The SES of the ADB is assessed using a conceptual framework rooted in the three pillars of sustainability science: social, economic, and ecological systems. The complex dynamics are explored with biophysical, socioeconomic, institutional, and local context-dependent mechanisms with a focus on institutions and land use and land cover change (LULCC) as important drivers of SES dynamics. This paper also discusses the following five pressing, practical challenges for the sustainability of the ADB SES: (a) reduced water quantity and quality under warming, drying, and escalating extreme events, (b) continued, if not intensifying, geopolitical conflicts, (c) volatile, uncertain, and shifting socioeconomic structures, (d) globalization and cross-country influences, and (e) intensification and shifts in LULCC. To meet the varied challenges across the region, place-based, context-dependent transdisciplinary approaches are needed to focus on the human-environment interactions within and between regional landscapes with explicit consideration of specific forcings and regulatory mechanisms. Future work focused on this region should also assess the role of the following mechanisms that may moderate SES dynamics: socioeconomic regulating mechanisms, biophysical regulating mechanisms, regional and national institutional regulating mechanisms, and localized institutional regulating mechanisms.This study was primarily supported through the LCLUC program of NASA (80NSSC20K0410, NNH18ZDA001N, 80NSSC20K0411, NNX15AD51G, NNX15AP81G). Partial support was provided by the Center for European, Russian and Eurasian Studies at MSU P Groisman has been supported by the NSF Grants (1558389, 1717770, 2019691) through The George Washington University, USA; the Fulbright Global Scholar program provided collaborative support to revise the manuscript at the Martin Luther University to J Chen and C Furst. L Tian was funded by the National Key Research and Development Program of China (2019YFC0507801, 2019YFC0507805) and Basic Frontier Science Research Program of the Chinese Academy of Sciences (ZDBS-LY-DQC023). Zhaksylyk Sabitov discussed major dynasties and territories in Central Asia and the Middle East. We thank Max Paulus of the IOP publisher (ERL editorial office) to invite us for this follow up review to promote a major knowledge gap for the ADB regions. Three anonymous reviewers provided their very constructive suggestions to revise the manuscript. Kristine Blakeslee of MSU Press made careful copy editing of the manuscript
Vibrational spectra, force constants and quantum chemical calculations of μ-1,3-azide bridged triphenylphosphine complexes of copper(I) and silver(I)
No full textThe dimeric title compounds [(C6H5)3P]Cu2(N3)2 and [C6H5)3P]Ag2(N3)2 were synthesized and characterized by FT-Raman and IR spectroscopy. The two phases were not isotypic but possessed approximately the same molecular symmetry which was C2/2m. The assignment of the modes was supported by quantum chemical DFT calculations coupled with TED (Total Energy Distribution) analyses. The calculated (N[sbnd]N) force constants for the bridging –(NNN)– groups were directly comparable (f(N[sbnd]N) = 11.75 (Cu) and 12.19 N cm−1(Ag)) and harmonized well with those of the free azide anion in the binary alkali azides. The (N[sbnd]N) bond orders were obtained based on the calculated force constants (Siebert Bond Order, SBO) and Density-dependent electrostatic and chemical (DDEC6) method yielding SBO = 1.92 (Cu) and 1.96 (Ag) and BO = 2.00 (Cu) and 2.03 (Ag), respectively, indicating the presence of double bonds. The results underlined that the (N[sbnd]N) force constants and bond orders in the bridging azide units were practically unaffected by the nature of the central metal atoms and that they could be regarded as quasi isolated anions similar to those in the binary azide compounds.Koç University Surface Science and Technology Cente
Prososyal yalanın uygunluğu testi – çocuk formunun geçerlik ve güvenirlik çalışması
No full textChildren’s perceptions of lying behaviors and their evaluations about different types of lies are among the topics discussed in the field. It is seen that the studies conducted on this subject focus on the lies that are told with antisocial and prosocial intentions that are opposite to each other. Besides, only a few studies have addressed children’s assessments of lies which are told for prosocial reasons. In these studies, it is also known that the researchers used various stories while examining the extent to which children perceive lies as reasonable through different stories. In the current study, it is aimed to conduct the validity and reliability study of the “Reasonability of Prosocial Lie Test-Child Form” in order to see whether the stories whether the stories measure the concept in Turkish sample. In addition, it was investigated for which reasons prosocial lies are more appropriate by focusing on the prosocial type of lying. A total of 277 children, 144 girls and 133 boys, aged between 8 and 13 years, participated in the study. Within the scope of validity studies, an exploratory factor analysis was performed, and it was founded that the final version of the test has an 11-item structure, 6 of which are “politeness lies”, 3 of which are "collaborative lies" emerging after someone else's request, and 2 of which are “negative lies” told for own benefit. In addition, the internal consistency coefficients of the test and the test-retest reliability coefficients revealed that the test was also reliable. The results of the analysis showed that the Reasonability of Prosocial Lie Test-Child Form is a valid and reliable measurement tool that can be used to evaluate which types of lies are more appropriate for children in primary and secondary school.Publisher versio
Cyborg encounters: Three art-science interactions
No full textThis contribution includes three selected works from an exhibition on Cyborg Encounters. These works deal with hybrid connections of human and non-human species that (might) emerge as a result of enhancement technologies and bio-technological developments. They offer not only an artistic exploration of contemporary but also futuristic aspects of the subject. Followed by an introduction by Melike Şahinol, Critically Endangered Artwork (by Ayşe Melis Okay) highlights Turkey’s ongoing problems of food poverty and the amount of decreasing agricultural lands. It displays seeds of a promising endemic plant to mitigate these problems using the seeds of the Thermopsis Turcica, a herbaceous perennial endemic plant. Ecomasculinist Pregnancy (by Burak Taşdizen and Charles John McKinnon Bell) follows the design fiction methodology and illustrates a future scenario through a patient’s diary and the medical letters he receives during his pregnancy with an extinct sea-lion. Polluted Homes (by Beyza Dilem Topdal) is a fictional art installation consisting of polychaete species evolved in time under the ecological circumstances prevalent in the Bosphorus and the Sea of Marmara today. These works show, that manufacturing life has consequences, not only for the human body and its physical appearance, but also, for example, for gender orders, the social structure of society, and even the environment, and thus for (re)shaping (non)living matter and their environments. This Art-Science Collection intends to provide an impetus for debate about the extent to which cyborg encounters should be taken seriously.Publisher versio
Analysis of Turkey’s airport network structure and centrality in the opening-out period after the first wave of COVID-19: A complex network approach
No full textThere are a few studies present analyzing air transport structures of the countries, regions, and the world by using complex network theory. Although Turkey has a complex air network with 56 airports, thorough research has not been carried out applying complex network analysis to reveal the structure of the airport network in Turkey yet. Furthermore, the fact that Turkey is a developing economy and the role of air transport in this development is undeniable, and its use as a transit area due to its geopolitical location, together with social and political factors, makes it important to understand this air transport network in detail. Consequently, in this paper, Turkey's Airport Network (TAN) topology was explored by implementing concepts of complex network theory using domestic and international passenger flight data gathered from FlightRadar during the opening period after the first wave of Covid-19. The average path length and clustering coefficient for connectivity performance and centrality metrics (degree, betweenness, and closeness) were computed and the network correlations were also measured and compared with simulated random, small-world (SW), and scale-free (SF) network models. Also, structural similarities and differences with the air networks of other countries are revealed
Parametric effects on pool boiling heat transfer and critical heat flux: A critical review
No full textPool boiling heat transfer offers high-performance cooling opportunities for thermal problems of electronics limited with high heat fluxes. Therefore, many researchers have been extensively studying over the last six decades. This paper presents a critical literature review of various parametric effects on pool boiling heat transfer and critical heat flux (CHF) such as pressure, subcooling, surface topography, surface orientation, working fluid, and combined effects. To achieve an optimal heat removal solution for a particular problem, each of these parameters must be understood. The governing mechanisms are discussed separately, and various options related to the selection of appropriate working fluids are highlighted. A broad summary of correlations developed until now for predicting CHF is presented with their ranges of validity. While proposed correlations for predicting CHF have been quite promising, they still have a considerable uncertainty (625%). Finally, a correlation proposed by Professor Avram Bar-Cohen and his team (thermal management of electronics (TME) correlation) is compared with the experimental dataset published in previous studies. It shows that the uncertainty band can be further narrowed down to 612.5% for dielectric liquids by using TME correlation. Furthermore, this correlation has been enhanced to predict CHF values underwater above 50 W/cm2 by applying a genetic algorithm, and new perspectives for possible future research activities are proposed.Deutsche Forschungsgemeinschaft ; EVATEG Research Center at Ozyegin Universit
Modeling of food consumption behavior in the quarantine period applied during the coronavirus SARS-CoV2 (COVID-19) outbreak in Turkey
No full textThe spread of coronavirus worldwide has affected consumer behavior in many ways. This paper tries to investigate the impact of the SARS-CoV2 (COVID-19) on food consumption behavior of consumers. Food consumption motivation data were assessed and compared before, during, and after the quarantine. An online survey was conducted among about 900 people from 54 different cities in Turkey, between April and May 2020, trying to understand consumers’ changing behavior in their food choices, preferences, and habits during the pandemic period. The aim of this paper is (i) to examine how consumer preferences were influenced by the COVID-19 quarantine period, using an ordered probit analysis, and (ii) to identify differences in the preferences for the food itself, food disinfection and cooking, and shopping preferences before and during the quarantine. Finally, as per the consumers’ body mass index (BMI), correlation with their mood and eating frequencies was observed. The findings indicate that, under stress conditions, like the quarantine period, food preferences and eating behavior changed, and consumers put all those emotions and information into their consumption process.Publisher versio