Development of a nanogap fabrication method for applications in nanoelectromechanical systems and nanoelectronics

There is a great need for a well-controlled nanogap fabrication technique compatible with NEMS applications. Theoretically, a displacement sensor based on vacuum tunnel junction or a nanogap can be capable of performing quantum-limited measurements in NEMS applications. Additionally, in the context of nanoelectronics, nanogaps are widely demanded to characterize nanostructures and to incorporate them into nanoscale electronic devices. Here, we have proposed and implemented a fabrication technique based on the controlled shrinkage of a lithographically defined gap between two suspended structures by thermal evaporation. We have consistently produced rigid and stable metallic vacuum tunneling junctions at nanometer or subnanometer sizes. The fabricated nanogaps were characterized by I-V measurements and their gap sizes and potential barrier heights were interrogated using the Simmons' model. Throughout this work, high tensile stress silicon nitride thin films were preferred for the fabrication of suspended structures because they have high resonance frequencies with low dissipation, they are mechanically stable, and they are resilient to stiction problem. However, high-stress nitride structures experience a complex shape deformation once they are suspended. The shape deformation is undesired when the precise positioning of the structures is required as in nanogap fabrication. We developed a new method in which the built in stress gradient is utilized to tune the distance between two suspended structures. The technique was simulated by finite element analysis and experimentally implemented to demonstrate a gap tuning capability beyond the lithographic resolution limits

Growth of thin graphene layers on stacked SiC surface in ultra high vacuum

We demonstrate a technique to produce thin graphene layers on C-face of SiC under ultra high vacuum conditions. A stack of two SiC substrates comprising a half open cavity at the interface is used to partially confine the depleted Si atoms from the sample surface during the growth. We observe that this configuration significantly slows the graphene growth to easily controllable rates on C-face SiC in UHV environment. Results of low-energy electron diffractometry and Raman spectroscopy measurements on the samples grown with stacking configuration are compared to those of the samples grown by using bare UHV sublimation process

MH-REACH-Mote: supporting multi-hop passive radio wake-up for wireless sensor network

A passive wake-up radio in a wireless sensor network (WSN) has the advantage of increasing network lifetime by using a wake-up radio receiver (WuRx) to eliminate unnecessary idle listening. A sensor node equipped with a WuRx can operate in an ultra-low-power sleep mode, waiting for a trigger signal sent by the wake-up radio transmitter (WuTx). The passive WuRx is entirely powered by the energy harvested from radio transmissions sent by the WuTx. Therefore, it has the advantage of not consuming any energy locally, which would drain the sensor node's battery. Even so, the high amount of energy required to wake up a passive WuRx by a WuTx makes it difficult to build a multi-hop passive wake-up sensor network. In this paper, we describe and discuss our implementation of a battery-powered sensor node with multi-hop wake-up capability using passive WuRxs, called MH-REACH-Mote (Multi-hop-Range EnhAnCing energy Harvester-Mote). The MH-REACH-Mote is kept in an ultra-low-power sleep mode until it receives a wake-up trigger signal. Upon receipt, it wakes up and transmits a new trigger signal to power other passive WuRxs. We evaluate the wake-up range and power consumption of an MH-REACH-Mote through a series of field tests. Results show that the MH-REACH-Mote enables multi-hop wake-up capabilities for passive WuRxs with a wake-up range of 9.4m while requiring a reasonable power consumption for WuTx functionality. We also simulate WSN data collection scenarios with MH-REACH-Motes and compare the results with those of active wake-up sensor nodes as well as a low power listening approach. The results show that the MH-REACH-Mote enables a longer overall lifetime than the other two approaches when data is collected infrequently.Peer ReviewedPostprint (author's final draft

EXPLORING INTERCULTURAL SENSITIVITY LEVEL AT A STUDY-AT-HOME CONTEXT

Development of intercultural competence is a term that is mostly researched about learners who have experience in study-abroad contexts. Considering that we are living in a globalized world where trade, mass-media, the Internet, and various exchange programs have allowed people to interact with culturally-others without going abroad, we assume that intercultural sensitivity is worth investigating also for learners who have solely studied at their home countries. It is certain that in addition to consumption of foreign products such as movies, songs, and books, university learners have also wide options of enjoying cultural diversity through international teachers, exchange students on campus, or via social media, all of which are channels linked to intercultural sensitivity development. In this study, we questioned the influence of interacting with foreigners on study-home university students by investigating the intercultural sensitivity level of a group of Turkish EFL learners who have never studied abroad. Moreover, in order to research if international teachers make a significant difference in the intercultural sensitivity level of language learners, we compared two groups: one group of students who studied English with only Turkish EFL teachers and another group who studied English with international teachers more than 7 hours weekly. As the data collection tool, both groups were given a questionnaire consisted of two parts: the Intercultural Sensitivity Scale by Chen & Starosta (2000) and study-specific posed open-ended & multiple choice questions. The results showed that both groups achieved high levels of intercultural sensitivity though the participants who have been regularly taught by international instructors achieved higher scores in several subscales of the questionnaire.  Article visualizations

Değişen politikalar, değişen hayatlar: Tek-endüstrili kentlerde yerel gelişme ve özelleştirme rabıtası

This paper dwells on how single-industry towns (SITs) locally develop and are affected by the privatization of those dominant sectors. To do so, we attempt to discuss the potential results of local development and privatization tension in SITs. Typically, SITs are where one dominant industry becomes the leading actor in the local socioeconomic structure. As a result of the statist planning approach, the SIT policy was implemented in Türkiye by the Central Governments for years, starting with the Five-Years Industrial Development Plans in 1934 and 1938. In line with these plans, building state-owned firms (SOFs) in specific locations implies fostering local and regional socioeconomic development while accelerating national industrial progress. Nevertheless, this statist and well-planned policy to utilize SOFs for SIT formation has shifted over the years. Under the local socioeconomic influence of an SOF, Erdemir, the city of Karadeniz Ereğli, Türkiye, has been a typical case of SIT formation. The Turkish Government’s policy to build the iron and steel company in the small coastal town during the 1960s stimulated the city’s evolution to an industrial city and reformed its structure as an SIT. However, the heritage of the early Republic’s planned statist policies that lasted more than forty years in Ereğli has shifted with the privatization of Erdemir in 2006. Whereas Erdemir’s privatization contributed to the national economic growth, the city’s local socio-economic development has shrunk. This paper, utilizing a qualitative research design following a theoretical discussion through secondary data sources, asserts that SITs are locally vulnerable to Central Governments’ policy shifts and especially privatization. Hence, we stress that the Governments’ shifting policies regarding local areas deeply affect those local people’s lives.Bu çalışma, tek-endüstrili kentlerin (TEK) yerel olarak nasıl geliştiğine ve barındırdıkları baskın aktörlerin özelleştirilmelerinden nasıl etkilendiğine vurgu yapmaktadır. Bu bağlamda, araştırmada TEK’ler özelinde yerel gelişme ve özelleştirme geriliminin sonuçları gösterilmeye çalışılmıştır. Genel olarak TEK’ler, yerel sosyoekonomik yapıda tek bir baskın endüstriyel kuruluşun lider aktör olduğu yerlerdir. Devletçi uygulamaların bir sonucu olarak Türkiye’de merkezi hükümetler uzun yıllar boyunca TEK politikalarını uygulamıştır. Bu politikalar, belirli bölgelerde kamu fabrikalarının kurulmasıyla ülke çapında sanayi ilerlemesini güçlendirirken aynı zamanda yerel ve bölgesel sosyoekonomik gelişmeyi de desteklemeyi ifade etmektedir. Ancak geçen zamanda, kamu fabrikaları aracılığıyla TEK’lerin kurulması yönündeki devletçi politika değişime uğramıştır. Bir kamu fabrikası olan Erdemir’in yerel sosyoekonomik etkisi altısındaki Karadeniz Ereğli, Türkiye, TEK yapılanması için tipik bir örnektir. Merkezi hükümetin 1960’lı yıllarda gerçekleştirdiği bir sahil kasabasında demir çelik fabrikası kurulması politikası, Ereğli’nin bir sanayi kentine evrilmesini ve TEK olarak yeniden kurgulanmasını dürtülemiştir. Ancak Ereğli’de kırk yıl boyunca takip edilen devletçi politika, Erdemir’in 2006’da özelleştirilmesi ile terk edilmiştir. Erdemir’in özelleştirilmesi ülkenin ekonomik büyümesini desteklerken, kentin yerel sosyoekonomik gelişimini engellemiştir. Bu çalışma, nitel araştırma deseni aracılığıyla TEK’lerin merkezi hükümetlerin politika değişimlerine ve özelleştirmelere yerel kırılganlığını ileri sürmektedir. Böylece, değişen politikalar, bireylerin hayatlarını da derinden etkilemektedir

Amerikan stratejik kültürü ve dış politikasını Robert Kagan üzerinden anlamak: Bir inceleme

This study is an outcome of the IR663 Ph.D. level course at METU Department of International Relations. Hence, the author wants to thank Prof.Dr. Huseyin Bagci, the instructor of the course, for his guidance and support.This paper aims to understand how the American strategic culture and perception of security have been shaped over time and what its main features are. American strategic culture has been nourished from the historical, geographical, and political realities of the country. Being a country founded by immigrants, making a great America was also part of the nation-building process. Moreover, the continent's geographical conditions have led the United States of America to be a more powerful state to intervene in political and military issues worldwide. According to Robert Kagan, the interventionist character, the role of security provider, and disfavoring the international law and organizations are the American foreign policy's main features. In this respect, this paper focuses on these three aspects and evaluate them in its limitation. Although there are many studies upon American foreign policy, this study diverges itself from the existing literature by putting Robert Kagan’s interpretations to its center.Bu çalışma, Amerikan stratejik kültürü ve güvenlik algısının zamanla nasıl şekillendiğini ve temel özelliklerinin neler olduğunu anlamayı amaçlamaktadır. Amerikan stratejik kültürü, ülkenin tarihsel, coğrafi ve siyasal gerçekliklerinden beslenmektedir. Göçmenler tarafından kurulmuş bir ülke olarak Amerika’nın güçlü bir ülke yapılması aynı zamanda ulus inşası sürecinin de bir parçasıydı. Dahası, kıtanın coğrafi koşulları Amerika Birleşik Devletleri’ni dünya çapında siyasal ve askeri olaylara müdahale etmek için daha da güçlü bir devlet yapmaya itmiştir. Robert Kagan’a göre, müdahalecilik, güvenlik sağlayıcılık ve uluslararası hukuku ve organizasyonları ikinci plana atmak Amerikan dış politikasının temel özellikleridir. Bu bağlamda çalışma, bu üç boyuta odaklanmakta ve bunları değerlendirerek kısıtlanmıştır. Amerikan dış politikası üzerine yazılmış birçok çalışma olsa da bu çalışma Robert Kagan’ın yaklaşımlarını merkeze alarak kendini mevcut literatürden farklılaştırmaktadır

Range Density Function for Active Sensor Imaging

In this paper, a generalised target density function (TDF) is studied for active imaging bysensors such as radar. This is achieved by estimating a new TDF which is called range densityfunction (RDF). It is proposed by utilising of a generalised range-angle density function forimaging. While the RDF is developed by a new approach based on inverse Wandermonde matrixcomputation, it is obtained by considering a new range and scanning angle plane different fromthe conventional methods

A perspective on critical security concept and international migration nexus through Copenhagen School: The quest for societal security

This study dwells on the quest for a critical security perspective on international migration. Therefore, how international migration could be perceived through critical security studies is the main research question of this study. Critical Security Studies (CSS) or Welsh School of security studies emerged after Robert Cox’s debate between problem-solving and critical theories, especially after the 1990s. In this respect, CSS focus on questioning the mainstream theories and their interpretation of security. Instead of accepting the state as the referent object, critical security studies provide other elements that may be threatened, so that related to the security. On the one hand, CSS is, therefore, critical against the traditional approaches to security as realism and liberalism. Securitization, on the other hand, as Copenhagen School provided a speech act to put an issue into the field of security. International migration is one of the accurate examples of securitization. In this study, we employed CSS and securitization perspectives to international migration to understand how international migration could be assessed through critical theories

An empirical analysis of securitization discourse in the European Union

This study aims to analyse the empirical background of securitisation in the European Union (EU). Using panel data, this research covers the period between 2006 and 2018 and analyses 24 EU countries. Copenhagen School claims that securitisation is a speech act of powerful actors. In the case of the EU, politicians and media are the main actors in the securitisation of immigration. In this respect, immigration has been labelled by these actors as a potential threat to the welfare state, European identity, and internal security. Various literature discusses that the securitisation of immigration in the EU has accelerated especially after 9/11. Contrary to the existing literature, this study focuses on the EU to analyse whether the securitisation of immigration has an empirical base. This study’s key finding is that there is no solid empirical result to support the securitisation discourse in the EU to the extent that immigration strongly threatens national security