NDT of Composites by Thermography

This paper describes ongoing research efforts to evaluate thermographic techniques for locating flaws or damage in structural fiber composite laminates. An infra-red camera with video isotherm readout is used to identify perturbations in uniform or linear thermal fields which may be caused by presence of flaws or damage such as matrix cracks, delaminations, blind side impact damage, and partial through holes. This procedure has potential for rapid qualitative screening of large surface areas. Potential defective areas may then be analyzed by a more accurate (but more time consuming) method . Two techniques are discussed; externally applied thermal field (EATF) and stress-generated thermal field (SGTF). The EATF technique involves applying heat to a composite structure and observing theresulting transient thermal pattern. The SGTF technique requires stress cycling to create hot spots in regions of high stress concentrations adjacent to flaws or damage sites

Flow instability in a vertical annulus under steady state and transient conditions

Experimental data have been obtained for the occurrence of flow instability in a vertical annulus under steady state and transient down-flow conditions. The results show that the primary factor affecting the onset of flow instability is the Q{sub ratio} parameter (a measure of the void production in a channel). In addition, it is shown that for steady state conditions good agreement exists between the single annulus data and single tube data based upon the same L/D ratio. The results also indicate that under transient operation the Q{sub ratio} can be used as a stability criterion

Flow instability and critical heat flux in a ribbed annulus

An experimental program has been conducted to determine the onset of flow instability point in a heated annulus which is divided into four sub channels by non-conducting ribs. The onset of flow instability is identified by the minimum point in the pressure drop-velocity curve. Comparison with a ribless annulus show that the presence of ribs increases the minimum point velocity. In addition, data are presented which show that under certain conditions premature CHF can be induced by the ribs

Flow instability in a vertical annulus under steady state and transient conditions

Experimental data have been obtained for the occurrence of flow instability in a vertical annulus under steady state and transient down-flow conditions. The results show that the primary factor affecting the onset of flow instability is the Q{sub ratio} parameter (a measure of the void production in a channel). In addition, it is shown that for steady state conditions good agreement exists between the single annulus data and single tube data based upon the same L/D ratio. The results also indicate that under transient operation the Q{sub ratio} can be used as a stability criterion

Data from: Patterns of cyto-nuclear linkage disequilibrium in Silene latifolia: genomic heterogeneity and temporal stability

Non-random association of alleles in the nucleus and cytoplasmic organelles, or cyto-nuclear linkage disequilibrium (LD), is both an important component of a number of evolutionary processes and a statistical indicator of others. The evolutionary significance of cyto-nuclear LD will depend on both its magnitude and how stable those associations are through time. Here, we use a longitudinal population genetic data set to explore the magnitude and temporal dynamics of cyto-nuclear disequilibria through time. We genotyped 135 and 170 individuals from 16 and 17 patches of the plant species Silene latifolia in Southwestern VA, sampled in 1993 and 2008, respectively. Individuals were genotyped at 14 highly polymorphic microsatellite markers and a single-nucleotide polymorphism (SNP) in the mitochondrial gene, atp1. Normalized LD (D′) between nuclear and cytoplasmic loci varied considerably depending on which nuclear locus was considered (ranging from 0.005–0.632). Four of the 14 cyto-nuclear associations showed a statistically significant shift over approximately seven generations. However, the overall magnitude of this disequilibrium was largely stable over time. The observed origin and stability of cyto-nuclear LD is most likely caused by the slow admixture between anciently diverged lineages within the species’ newly invaded range, and the local spatial structure and metapopulation dynamics that are known to structure genetic variation in this system

Comparison of computer aided production system with the conventional production system in a yatch furniture manufacturing factory

YÖK Tez No: 309237Bu çalışmada; yat ve gezi teknelerine özel mobilyaların üretilmesinde bilgisayar destekli üretim (BDÜ) ve geleneksel üretim (GÜ) uygulamaları incelenmiştir. Mobilyaların CNC makinesinde üretilebilirliği, mobilya adedi, parça sayısı, levha miktarı ve işlem zamanı gibi parametreler esas alınarak değerlendirilmiştir.Araştırma kapsamında HardTop 78 (HT 78) teknesine ait 60 farklı mobilyanın üretimi gerçekleştirilmiştir. Elde edilen veriler MS Project ve Excel 2007 programında değerlendirilmiştir. BDÜ'de üretim için gerekli olan programlama ve diğer hazırlıklar CNC makinesi, WoodWOP 5.0 ve CutRiteV81 paket programları kullanılarak yapılmıştır.Araştırma sonucunda; HT 78 teknesine ait 60 farklı mobilyanın tamamı GÜ sisteminde üretilebilirken, BDÜ sisteminde ise %68'i (42 adet) %100 üretilebilmektedir. Tüm mobilyaların %32'si (19 adet) ise kısmen BDÜ'de üretilebilir olduğu ortaya çıkmıştır. HT 78 teknesine ait mobilyalar 943 adet parçadan oluşmaktadır. Tüm parçaların %95'i (894 adet) BDÜ'de üretilebilmektedir. %5'nin (49 adet) ise BDÜ'de üretimi yapılamamaktadır. Tekne mobilyaları toplam 277 m2 levhadan meydana gelmektedir. Tüm levha miktarının %91'i (253 m2) BDÜ'de üretilebilmektedir. %9'u (24 m2) ise GÜ sisteminde üretilmesi gerektiği ortaya çıkmıştır.Makinelerin işletmeye maliyetleri 2006 ile 2008 yılları arasındaki fiyatları baz alınarak karşılaştırılmıştır. GÜ'de kullanılan 13 adet konvansiyonel makinenin toplam yatırım maliyeti 106.993 ? iken BDÜ'de kullanılan 3 adet makinenin yatırım maliyeti 341.091 ? olduğu ortaya çıkmıştır. GÜ'de kullanılan makine maliyetleri incelendiğinde BDÜ'ye geçişte işletme için ilk yatırım maliyeti 3.18 kat arttığı tespit edilmiştir.Araştırma sonuçlarına göre yat mobilyalarının üretiminde BDÜ sistemlerinin kullanılmasının işletmeler için daha avantajlı olduğu ortaya çıkmıştır. Makine kapasitesinin ve esnekliğinin sağladığı avantajlar arasında; personel sayısının azalması ve üretilen ürün kalitesindeki standartların kalıcı olması, üretim süresinin kısalarak daha hızlı üretim yapılması ve müşteri taleplerinin hızlı bir şekilde karşılanabilmesi gibi üretimin farklı değişkenlerinde olumlu sonuçlar elde edilmiştir.Yat mobilyası gibi genel kullanıma ait mobilyalardan belirgin farklılıklar içeren mobilyaların tasarım sürecinde, mevcut üretim sisteminin yapısı ve üretilebilirlik değerlendirmesinin daha dikkatli yapılması gerekmektedir.Bu amaçla işletmeler Araştırma-Geliştirme çalışmalarına daha çok önem vermeli, CNC makinesi değerlendirme ve seçimleri daha hassas bir şekilde yapılması önerilmektedir.In this study; manufacturing of special furniture for yacht and cruise boats with computer aided manufacturing and conventional manufacturing systems and their manufacturability with CNC machines according to the quantity of furniture, piece and amount of boards were investigatedThe production of 60 different types of furniture for Hardtop 78 project is done with conventional machines. Data gained from this production are saved on Project and Excel 2007 software. As the selection of furniture for computer aided manufacturing, VIP cabin set identical to the 78 feet model and other test furniture were determined. Preparation for computer aided manufacturing is satisfied with CNC machines and its related software. Comparison is done with the data gained from two different manufacturing systems.As a result of study, 60 different furnitures of 78 hardtop project are 100% producible by traditional manufacturing system, but 68%(42 furniture) are producible compeletely by computer aided manufacturing. For all furniture only 32% (19 furniture) are participally producible by computer aided manufacturing system. The furnıture of 78 hardtop includes 943 components. When total number of furniture pieces is examined, 95% (894 pieces) is producible by computer aided manufacyuring system, 5% (49 pieces) is needed to be produced by traditional manufacturing system. Yacht furnitures include 277 m2 boards. 91% (253 m2) of all boards can be produced by computer aided manufacturing system, %9?u (24 m2 ) can be produced by traditional manufacturing system.The comparison between the costs of machines to the companies is based on the prices between 2006 to 2008. The total cost of 13 machines used in traditional manufacturing is 106.993 ? and 3 machines? used in computer aided manufacturing is 341.091 ?. It is identified that when the costs of machines are studied, the transition from traditional manufacturing to computer aided manufacturing is ricing up to the initial investment costs 3.18 times.In this study, it is determined that computer aided manufacturing system is advantageous for yacht furniture production. Beside the advantages of capacity and flexibility of machines, reduction in the number of employees, permanence in quality and standards of furniture, speeding up the manufacturing process and meeting customer demands more quickly are the other major advantages.At the phase of investment for the CNC and other machines that is needed to use for producing special furnitures such as yatch furnitures, the experts should study on construction of furnitures, materials is used and etc. for suitability to furnitures planned to manufacture.It is observed that CNC machine user companies should pay attention to design of furniture for manufacturability in CNC machines. Production development and manufacturing development departments should gain more importance in the companies. It is suggested to managers of such companies to have experts to make more feasibility studies on manufacturing