311 research outputs found

    Diffusion of innovations in social networks

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    While social networks do affect diffusion of innovations, the exact nature of these effects are far from clear, and, in many cases, there exist conflicting hypotheses among researchers. In this paper, we focus on the linear threshold model where each individual requires exposure to (potentially) multiple sources of adoption in her neighborhood before adopting the innovation herself. In contrast with the conclusions in the literature, our bounds suggest that innovations might spread further across networks with a smaller degree of clustering. We provide both analytical evidence and simulations for our claims. Finally, we propose an extension for the linear threshold model to better capture the notion of path dependence, i.e., a few minor shocks along the way could alter the course of diffusion significantly.Charles Stark Draper Laboratory. Independent Research and Development. University Research & DevelopmentNational Science Foundation (U.S.). (Grant number SES-0729361)United States. Air Force Office of Scientific Research (Grant number FA9550-09-1-0420)United States. Air Force Office of Scientific Research. (Grant number W911NF-09-1-0556

    Practical Coding Algorithms for Consensus Problems with Zero Asymptotic Rate

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    This item was originally submitted by Mehmet Yildiz ([email protected]) on 2007-04-30T19:47:25Z. After corrections it was resubmitted by Mehmet Yildiz ([email protected]) on 2007-05-01T21:04:43Z, and approved for entry into archive by Minnie Empson([email protected]) on 2007-05-02T18:36:31Z (GMT). The original handle was https://hdl.handle.net/1813/7542. Because of a problem with the original record, it had to be deleted and resubmitted and assigned a new handle.We consider the average consensus algorithm under the rate constraint communication network. Average consensus algorithms are protocols to compute the average value of all sensor measurements via near neighbors communications. The main motivation for our work is the observation that consensus algorithms offer the perfect example of a network communication problem where there is an increasing correlation between the data exchanged, as the algorithm iterates. Henceforth, it is possible to utilize previously exchanged data and current side information to reduce the demands of quantization bit rate for a certain precision. We analyze the case of a network with a topology built as that of a random geometric graph and with links that are assumed to be reliable at a constant bit rate. We explore the conditions on the quantization noise which lead to a consensus value whose mean squared distance from the initial average is bounded. We propose two main practical schemes and show that they achieve bounded convergence with zero rate asymptotically. We further investigate the problem under regular grid network assumption and observe that computational complexity of the schemes reduce significantly and global knowledge of the network connectivity assumption can be relaxed. Thus, we conclude that the proposed schemes become scalable under dense networks

    FARKLI ORTAMLARA MARUZ KALAN BAZI AHŞAP ESASLI LEVHALARIN MÜHENDİSLİK ÖZELLİKLERİNİN İNCELENMESİ

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    Günümüzde ahşap esaslı levhalar; kontrplak, mdf, sunta, ahşap dik yongalı levhalar, ahşap yatık yongalı levhalar, playwood vb. olarak sınıflandırılmaktadır. Bu çalışmada, farklı ortamlara maruz kalan ahşap esaslı levhalardan bazılarının mühendislik özeliliklerindeki değişimler incelenmiştir. Bu amaçla, yaygın kullanımları nedeniyle Yonga Levha (Sunta), Lif Levha ( MDF) ve Kontrplak levhalar farklı ortamlara maruz bırakılarak mühendislik özellikleri belirlenmiştir. Bu levhalardan TS EN 317’ye uygun olarak kenar uzunluğu 50±1 mm olan kare kesitli numuneler hazırlanmıştır. Bu numuneler;  şartlandırma, suya daldırma, dondurma, etüvde kurutma işlemlerine tabi tutulmuş ve her işlem sonunda boy, kalınlık, ağırlık, kalınlık doğrultusunda şişme oranları ile su emme oranları ölçülmüştür. Her malzeme için elde edilen deneysel sonuçlar o malzemenin referans değerleri ile karşılaştırılarak yorumlanmıştır. Buna göre, kontrplak için ortalama su emme ve kalınlık doğrultusunda şişme oranlarının sırasıyla %36.31 ve %5.26 olduğu, mdf için %20.38 ve %0.91 olduğu ve sunta için ise bu oranların %80.04 ve %7.24 olduğu belirlenmiştir.  Deneylerle elde edilen sonuçların malzeme grubuna göre istatistiksel olarak birbirinden farklı olup olmadığının belirlenmesi amacıyla da varyans analizi ve gruplar arası çoklu karşılaştırma testleri yapılmış ve analiz sonuçları referans değerlerle karşılaştırılmıştır

    Effects of Rhizobacteria Application on Leaf and Fruit Nutrient Content of Different Apple Scion–Rootstock Combinations

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    The plant pomological characteristics and physiological behaviors of genotypes in modern apple cultivation could be different depending on the use of rootstock, changing growth ecology and application of biological control agents. The aim of this research was to determine the effects of rhizobacteria application on leaf and fruit nutrient contents in different apple scion–rootstock combinations. This study was carried out with seven standard cultivars (Scarlet Spur, Red Chief, Fuji, Jeromine, Galaxy Gala, Granny Smith, and Golden Reinders) budded on M.9 and MM.106 rootstocks. In the experiment, trees were sprayed by a nitrogen + phosphorus solvent rhizobacteria three times, with an interval of 15 days in the spring period. The effect of rhizobacteria application on leaf and fruit nutrient contents was statistically significant and provided generally significant positive contributions, except for leaf Mg content. Comparing both rootstocks, the positive effect of bacterial application was higher on the M.9 rootstock for leaf N and B content and fruit N and Fe content, and on the MM.106 rootstock for other nutrient content. While the effects of bacterial application on the basis of cultivars were generally positive, the highest positive contribution was made in leaf P content (10.7%) and fruit Mn content (32.1%) of the Fuji cultivar. Considering the total increase in nutrients in scion–rootstocks combination, rhizobacteria application had a positive effect on the leaf nutrient contents in Golden Reinders/MM.106, but not leaf K content. The highest increases in leaves of scion-rootstock combinations were determined as 4.0% in N content in Granny Smith/M.9, 14.1% in P content in Scarlet Spur/MM.106, 7.1% in K content in Fuji/MM.106, 4.4% in Ca content in Jeromine/M.9, and 14.0% in Mg content in Granny Smith/MM.106. The highest increase in fruit nutrient contents was between 4.9% (N content) and 13.5% (Ca content) for macro elements, and between 9.5% (Cu content) and 41.8% (Mn content) for microelements. The results of the present study may provide significant leads for further studies on this subject.Effects of Rhizobacteria Application on Leaf and Fruit Nutrient Content of Different Apple Scion–Rootstock CombinationspublishedVersio

    EFFECTS OF CHRONOLOGICAL AND THEMATICALLY DESIGNS OF HISTORY TEXTBOOKS ON STUDENT ACHIEVEMENT "REVOLUTIONARY MOVEMENTS IN EDUCATIONAL AND CULTURAL FIELDS"

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    TARIH DERS KITAPLARIN1N BCRONOLOJIK VE TEMATIK TASARIMLARININ OGRENCI BASARISI UZERINDEKi ETKBLERi "EGITIM VE KTJLTUR ALANINDA YAPILAN iNKILAP HAREKETLERI" Ercan, Yildiz Yuksek Lisans, Tarih Ogretmenligi Bilim Dali Tez Danismani: Yrd. Doc. Dr. Mehmet Ali CAKMAK Subat-2007 Bu arastirma tarih konulanmn islenisinde tarih ders kitaplannin kronolojik veya tematik tasanmlannm ogrenci basansi iizerindeki etkisini belirlemeyi ama9lamaktadrr. Arastirmanin cahsma evrenini 2006-2007 egitim-ogretim yih, Ankara ili, Altindag il9esindeki liselerin 3. sinif ogrencileri, omeklernini Altmdag ilcesi Esenevler Anadolu Lisesi 11-SOS-A ve 11-SOS-B simflanmn ogrencileri olu§turmustur. Arastirma 27'si deney grubu, 29'u kontrol grubu olmak uzere toplam 56 denek ile yurutulmustur. Arastirmada ontest- sontest kontrol gruplu model kullamlmistir. Ara§trrmaya ySnelik uygulama sonunda elde edilen verilerin analizi S.P.S.S. 13 programi ile yapihm§tir. Ara§tirmaya yonelik uygulama sonunda yapilan istatistiksel i§lemler sonucu kronolojik tasarlanmis ders kitaplan ile tarih konulannm kronolojik islenisinin tematik islenise gore ogrenci basansi iizerinde daha olumlu etkiye sahip oldugu tespit edilmistir. Arastirma sonunda elde edilen bulgulara dayali olarak arastmnaci tarafindan ortaya konulan oiierilere yer verilmistir.EFFECTS OF CHRONOLOGICAL AND THEMATICALLY DESIGNS OF HISTORY TEXTBOOKS ON STUDENT ACHIEVEMENT "REVOLUTIONARY MOVEMENTS IN EDUCATIONAL AND CULTURAL FIELDS" Ercan, Yildiz Degree of Graduate, Department of History Education Thesis Advisor: Ass. Prof. Dr. Mehmet Ali £AKMAK February - 2007 This research has aimed to determine the effects of chronological and thematically designs of history textbooks on student achievement in the instructions of history subjects. 3r grade class students of high schools in the district of Altindag in province of Ankara in the 2006-2007 academic year have formed the working environment of the research and on the other hand, the students of 11-SOCIAL-A and 11-SOCIAL-B classes in Esenevler Anatolian High School in the district of Altindag have formed the sampling of the research. The research has been conducted through totally 56 subjects consisting of 27 experimental groups and 29 control groups. A model including pre-test and post-test control group has been applied to the research. The analysis of the data obtained at the end of the application directed at the research has been made by S.P.S.S. 13 program. As a result of statistical processes made at the end of the application directed at the research, it has been determined that the chronological instruction of history subjects using textbooks designed chronologically has a more positive effect on student achievement than the instruction thematically. At the end of the research, it has been mentioned about suggestions stated by the researcher based on the findings obtained
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