279 research outputs found

    SOME VECTORS FIELDS ON THE TANGENT BUNDLE WITH A SEMI-SYMMETRIC METRIC CONNECTION

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    Let MM is a (pseudo-)Riemannian manifold and TMTM be its tangent bundlewith the semi-symmetric metric connection \overline{\nabla }. In thispaper, we examine some special vector fields, such as incompressible vectorfields, harmonic vector fields, concurrent vector fields, conformal vectorfields and projective vector fields on TMTM with respect to thesemi-symmetric metric connection \overline{\nabla } and obtain someproperties related to them

    Optimization of SASE operation for an X-ray free-electron laser Using multiple objective evolutionary algorithms

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    Performance of Self Amplifed Spontaneous Emission (SASE) operation for an X-ray Free-Electron Laser (FEL), is optimized by Multiple Objective Evolutionary Algorithms (MOEA). Different types of hybrid planar undulators are considered to achieve 0.5 Å ≤ λFEL ≤ 1.5 Å wavelength range. This demand is regarded as a continuous optimization problem, and hence, an evolutionary algorithm is designed to find optimal FEL performance parameters. An encoding scheme comprising of undulator period (λu) and undulator gap (g) is adopted here to find optimal values for saturation power (Psat) and λFEL subject to several physical constraints on λu and g such as the ratio of g/λu and Lsat. It is shown that MOEA gives optimal solutions for estimation of Lsat with plausible Psat values

    Optimization of SASE operation for an X-ray free-electron laser Using multiple objective evolutionary algorithms

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    635-641Performance of Self Amplifed Spontaneous Emission (SASE) operation for an X-ray Free-Electron Laser (FEL), is optimized by Multiple Objective Evolutionary Algorithms (MOEA). Different types of hybrid planar undulators are considered to achieve 0.5 Å ≤ λFEL ≤ 1.5 Å wavelength range. This demand is regarded as a continuous optimization problem, and hence, an evolutionary algorithm is designed to find optimal FEL performance parameters. An encoding scheme comprising of undulator period (λu) and undulator gap (g) is adopted here to find optimal values for saturation power (Psat) and λFEL subject to several physical constraints on λu and g such as the ratio of g/λu and Lsat. It is shown that MOEA gives optimal solutions for estimation of Lsat with plausible Psat values

    AC SERVO MOTOR EĞİTİM SETİ TASARIMI

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    Bu çalışmada, Marmara Üniversitesi Mekatronik Eğitimi Bölümünde bulunan Lucas Nülle firmasına ait AC Senkron Servo Motor seti, eğitim amaçlı, konum kontrolü yapan deney setine dönüştürülmüştür. Öğrencilerin deney setini daha efektif kullanabilmeleri için Siemens firmasına ait WinCC Flexible yazılımı ile bir ara yüz tasarlanmıştır. Konum, hız ve tork kontrollerinin yapılması için üç ayrı deney föyü hazırlanmıştır. Hazırlanan deney setinde AC motor kontrolünün yanı sıra bağımsız olarak PLC( Siemens S7-300) , Servo inverter (Lenze 9300 Position Control) kullanarak scada ve PLC’nin ileri seviye eğitimleri hedeflenmiştir. Yapılan bu çalışma, Mekatronik bölümü müfredatında bulunan Elektromekanik sistemler, Kontrol sistemleri ve Ölçme derslerinde kullanılacaktır

    THE USE OF SPECTRAL ENTROPY OF EEG TO PREDICT ANESTHESIA DEPTH ON THE DSPIC BASED SYSTEM

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    Anestezi derinliği ölçmek için birçok EEG (Elektroensaflogram) analiz yöntemi kullanılmaktadır. Bu yöntemlerin tümü çevrim dışı tabanlı olduğundan, gerçek zaman tabanlı yöntemlerin geliştirilmesine hala gereksinim vardır. Çalışmadaki amaç, derin anestezi ve uyanıklık durumlarının değerlendirilmesi için gerçek zaman dsPIC tabanlı EEG analiz sistemi geliştirmektir. Gerçek hipnogram değerleri ve hesaplanmış EEG tabanlı ölçümler arasında benzerlikler olduğu gösterilmiştir. Sonuç olarak bu çalışmanın anestezi izleme aygıtı geliştirmek için yeterli birikime sahip olduğu söylenebilir. Many of the EEG analysis methods are used to monitor the depth of anesthesia. All of these methods are off-line based; therefore, the real-time based methods still need to be developed. Our aim is to develop a real-time dsPIC based EEG analysis system for evaluating of deep anesthesia and of awake states. It was shown that there were quite similarities between the actual hypnogram values and the calculated EEG based measures. Consequently, we could say that this study has enough potential application to develop an anesthesia monitoring device

    Effect of Pruning on Diameter Growth in Pinus brutia Ten. Plantations in Turkey

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    Pruning is a technique used to add value to trees growing in forest stands, allowing the formation of clear, knot-free wood. Although many factors affect timber value, knots are the primary cause of reduction in timber quality of conifers. On the other hand, pruning may also cause reduction in the rate of tree growth, depending on pruning intensity.The aim of this study is to assess the effects of different pruning intensities on DBH (diameter at breast height) growth of young Pinus brutia plantations. For this purpose, three field experimental sites each with different site qualities, were established in three different locations. Four different treatments were applied at each test site: 1) control, no pruning of branches, 2) pruning up to 25% of tree height, 3) pruning up to 50% of tree height, and 4) pruning up to 75% of tree height. The effects of pruning on DBH growth were observed over a period of 14 years. At »Bük« test site, which has the poorest site quality, only those specimens pruned up to 75% of tree height showed significant reduction in DBH growth compared to the control. However, at »Nebiler« and »Kursunlu« test sites, specimens pruned both up to 50% and 75% of tree height showed statistically significant decrease in DBH growth. To recover from pruning stress in terms of DBH growth rate, it took trees 6 years at the poorest test site and 4 years at the relatively better test sites. This indicates that site quality of plantation sites accounts for not only DBH growth differences between sites, but also recovery rate of trees from any disturbances. Results showed that for those trees pruned up to 75% of their height, total DBH growth was reduced by between 6.5% and 9.0% after 14 years compared to the control at the test sites. No negative effect from pruning on DBH increment was observed in the first growing season. This may be due to earlier storage of nutrition in different parts of trees, thereby enabling them to compensate for the stress of crown reduction during the first growing season following pruning

    Assessment of human error contribution to container loss risk under fault tree analysis and interval type-2 fuzzy logic-based SLIM approach

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    Human is a key element of the safety of life on board ships and a significant contributing factor to most of the accidents and incidents in the maritime industry. At this point, risk analysis plays a critical role in ensuring operational safety and maritime transportation sustainability. This paper aims to systematically evaluate how human errors (HEs) contribute to operational risks. Based on this, Fault Tree Analysis (FTA) is combined under an Interval Type-2 Fuzzy Logic environment with Success Likelihood Index Method (SLIM). Whilst the FTA evaluates the criticality of the operational activities, the Interval Type-2 Fuzzy Sets (IT2FS) deals with vagueness and subjectivity in using experts’ judgments, and the SLIM estimates the probabilities for the human error-related basic events. Since container losses can lead to severe damage and catastrophic events in a container terminal, loading operation was investigated as a case study. Safety culture, experience, and fatigue were observed as highly effective factors in crew performance. The obtained results also indicate that this hybrid approach can effectively be applied to determine the operational vulnerabilities in high-risk industries. The paper intends to improve safety control levels and lower losses in the future of maritime container transport besides emphasizing the potential consequences of failures and crucial human errors in the operational process

    Black sea aquaculture: Legacy, challenges & future opportunities

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    Responsible aquaculture, the farming of aquatic organisms, is a sustainable strategic sector for land and coastal communities. It significantly contributes to food security and enhancement of economic development; it provides employment opportunities and often contributes to the ecological services provided by the environment. According to the Food and Agriculture Organization of the United Nations (FAO), the contribution of aquaculture to the global food security is widely demonstrated by an astounding industry growth of 7.5% per year since 1970. In 2018, aquaculture reached the all-time highest production of 114.5 million tonnes in live weight with a total farm gate sale value of USD 263.6 billion. This makes aquaculture a key player within the Blue Growth concept and a strong contributor to some of its key Sustainable Development Goals (SDG). This is particularly true in geographical areas where dependence of local economies on fishery products is high, and yet access to sustainable landings is hampered by ecological barriers. One such area is represented by the Black Sea basin. Whilst the Black Sea annual capture fishery production has varied considerably since 1990 and its current landings are significant, growing attention is currently given to boost aquaculture development along the Black Sea bordering countries, with marine aquaculture being considered as an important contributor to the total fisheries production. Nonetheless, aquaculture development in this region is not homogenous and its development has, so far, been limited by environmental, economic, social, and more generally governance issues. This paper, for the first time, attempts to provide a comprehensive fresh outlook of the aquaculture sector in the Black Sea, stressing the importance of regional cooperation as an essential pillar to support the sustainable development of the industry. The paper addresses aquaculture in the Black Sea from different perspectives: it outlines the key characteristics of the Black Sea environment; it discusses the most common farmed aquatic species and the potential for new ones; it frames the national approaches to aquaculture development, sharing information about success stories, while shedding light on the main challenges and priorities ahead. This collective endeavour will represent a helpful contribution to Black Sea riparian countries to answer the many questions they have, and expectations they hold from the aquaculture sector.Additional co-authors: Dilek Fidan, Linda Fourdain, Marco Frederiksen, Archil Guchmanidze, Housam Hamza, Jessica Harvey, Magda Nenciu, Galin Nikolov, Victor Niţă, Muhammed Doğan Özdemir, Elitsa Petrova-Pavlova, Gabriel Popescu, Ferit Rad, Şafak Seyhaneyildiz Can, John A. Theodorou, Behnan Thomas, Nicolò Tonachella, Ekaterina Tribilustova, Irina Yakhontova, Ahmet Faruk Yesilsu, Güzel Yücel-Gie
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