2,521 research outputs found
Al2O3- TiO2 (%97-3) Seramik Tozparçacık İlaveli Cam Elyaf Takviyeli Epoksi Matrisli Kompozit Malzemelerin Mekaniksel Özelliklerinin İncelenmesi
No full textBu çalışmada; cam elyaf takviyeli polimer matrisli kompozit malzemelerde Al2O3- TiO2(%97-3) seramik toz ilave parçacıkların malzemenin mekaniksel özelliklerine etkisi deneysel olarak incelenmiştir. Dokuma kumaş olarak; düz dokuma 270 gr/m2’lik kumaşlar kullanılmıştır. Matris malzemesi olarak epoksi reçine kullanılmıştır. Al2O3- TiO2 seramik tozlar reçinenin içerisine %5, %10, %15 katkı oranlarında ilave edilmiştir. Çekme deneyleri ASTM D3039-76 standardına göre yapılmıştır. Sonuçlar; cam elyaf takviyeli polimer matrisli kompozit malzemelerde, Al2O3- TiO2 (%97-3) seramik tozların kompozit malzemenin içinde artmasıyla, kompozit malzemelerin çekme dayanımları ve elastisite modüllerinin azaldığını göstermiştir
The Effect of Using Computer Technology Tools to Enhance the Teaching-Learning Process in CAD-CAM-CNC Module in Mechanical Engineering Subject Area
No full textThis study presents the evaluation of Computer Assisted Learning (CAL) package included in the teaching and learning methodology of computer aided design- computer aided design - computer numerical control (CAD-CAM-CNC) module.
Three groups of students with similar pre-abilities were exposed to three different teaching learning methodologies.The effectiveness of these three methods was determined by questionnaires completed by the students and collected by first author. Their answers were analysed quantitatively and qualitatively. The various categories used in the questionnaire was student’s attitudes towards learning CAD-CAM-CNC subjects, students’ opinions about their lecturers approaches to teaching process, students’ opinions and views about various aspects the CAD-CAM-CNC. The study concludes that the students taught with a combination of CAL package and traditional methods were more effective, efficient and satisfied with their learning experiences. So the proposed hybrid learning method (CAI plus traditional teaching method) is most suited for CAD-CAM-CNC teaching.
Computer Technology; Computer-Assisted Instruction (CAI); Computer Assisted Learning (CAL); Computer Aided Design (CAD); Computer Aided Manufacturing (CAM); Computer Numerical Control (CNC)
Nuclear translocation and signalling of L1-CAM in human carcinoma cells requires ADAM10 and presenilin/gamma-secretase activity
No full textL1-CAM (L1 cell-adhesion molecule), or more simply L1, plays an important role in the progression of human carcinoma. Overexpression promotes tumour-cell invasion and motility, growth in nude mice and tumour metastasis. It is feasible that L1-dependent signalling contributes to these effects. However, little is known about its mechanism in tumour cells. We reported previously that L1 is cleaved by ADAM (a disintegrin and metalloprotease) and that the cytoplasmic part is essential for L1 function. Here we analysed more closely the role of proteolytic cleavage in L1-mediated nuclear signalling. Using OVMz carcinoma cells and L1-transfected cells as a model, we found that ADAM10-mediated cleavage of L1 proceeds in lipid raft and non-raft domains. The cleavage product, L1-32, is further processed by PS (presenilin)/gamma-secretase to release L1-ICD, an L1 intracellular domain of 28 kDa. Overexpression of dominantnegative PS1 or use of a specific gamma-secretase inhibitor leads to an accumulation of L1-32. Fluorescence and biochemical analysis revealed a nuclear localization for L1-ICD. Moreover, inhibition of ADAM10 and/or gamma-secretase blocks nuclear translocation of L1-ICD and L1-dependent gene regulation. Overexpression of recombinant L1-ICD mediates gene regulation in a similar manner to full-length L1. Our results establish for the first time that regulated proteolytic processing by ADAM10 and PS/gamma-secretase is essential for the nuclear signalling of L1 in human carcinoma cell lines. Key words: a disintegrin and metalloprotease 10 (ADAM10), L1 cell-adhesion molecule (L1-CAM), nuclear translocation, presenilin (PS)/gamma-secretase activity, raft, signalling
COMPARISON OF CAM PROFILES OBTAINED VIA CLASSICAL SPLINE METHOD FOR DIFFERENT LIFTED-VALVE PERIODS AND LIFTS
No full textIn automobile engines cam profiles are designed with a particular attention to accomplish a silent operation and long term duration of the valve system. Running of the valve system without vibration as well as satisfying an appropriate lift and lifted-valve period is also related to cam design procedure. In this paper, effects of varying cam profiles on the speed, acceleration and jerk of the followers were comparatively studied. Using a 5(th) order classical spline method, cam profiles were obtained for 2.02 radian (116 degrees), 2.16 radian (124 degrees) and 2.3 radian (132 degrees) lifted-valve periods. For each of these periods cam profiles obtained for 5, 6 and 7 mm cam strokes were compared. For a 5 mm valve stroke and 41.6 mm basic circle diameter 2.02 radian (116 degrees) lifted-valve period provides a reasonable cam profile. However, for a 7 mm cam stroke and 41.6 mm basic circle diameter at least a 2.16 radian (124 degrees) lifted-valve period becomes necessary. If the lifted-valve period is increased to 2.3 radian (132 degrees), the cam profile becomes much better
Effects of right refractory material selection on tableware glass production efficiency
No full textCam üretim sanayisinin gelişmesiyle birlikte daha kaliteli ve maliyet avantajlı cam üretmek en önemli hususlar olmuşlardır. Sektörün gelişmesiyle birlikte cam ergitme fırınlarında kullanılan refrakter malzemelerin seçimi ve refrakter sanayisindeki gelişmeleri takip etmek de kaçınılmaz bir gerekliliktir. Bilindiği üzere, bir cam üretim sürecinde ergitme havuzu, çalışma havuzu ve forehearth denilen bölgeler cam ergitme fırınında temeli oluşturur. Bu araştırmanın amacı; cam üretiminde çeşitli hataların oluşmasına ve verim kaybına neden olan çalışma havuzu ve forehearthlarda kullanılan Alümina Zirkon Silikat (ER1618) refrakter yerine, daha az cam hatasına neden olacağı ve verimlilik artışında katkı sağlayacağı düşünülen Alfa Beta Yüksek Alümina (JARGAL®) refrakter kullanımı araştırılmıştır. Amaçlanan çalışmada öncelikle alümina zirkon silikat ve alfa beta yüksek alümina refrakter tuğlaların ve iki ayrı züccaciye fırınına ait cam numunelerinin karakterizasyonları XRF ve XRD ile belirlenmiştir. Daha sonra bağıl yoğunluk, sert kırma mukavemeti ve yük altında refrakterlik kıyaslama testleri refrakter malzemelerin fiziksel özelliklerinin değerlendirilebilmeleri için yapılmıştır. Temel refrakter kıyasları yapılması sonrasında refrakter tuğla ile cam arasındaki ilişkiyi ortaya koyabilmek adına eksüdasyon testi, taş dökme indeksi ve blistering testleri uygulanmıştır. Bu aşamalarda SEM mikro yapı analizleri ile ilgili ara yüzlerdeki durumlar görüntülü olarak karakterize edilmiştir. Yapılan araştırmalar sonucunda, züccaciye camı üretiminde AZS refrakter yerine, alfa beta yüksek alumina refrakter kullanımı ürünlerdeki refrakter kaynaklı hataları minimize ederek verimliliği olumlu etkileyecek ve uzun vadede daha ekonomik olacaktır.With the development of glass industry, the production of higher quality glass with reduced cost has
become vital. That is why, the selection of the refractory material used in the glass melting furnaces and
keeping up with the advances in the refractory industry is of utmost importance. Clearly; melting tank,
working tank and the so called forehearths are the building blocks of the glass production process. The
main purpose of this study is to investigate the use of Alpha Beta High Alumina (JARGAL®) refractory
which is expected to give rise to less glass defects and help to increase the overall efficiency of glass
production instead of Alumina Zirconia Silica (ER1618) refractory which causes various glass defects and
decreases the overall efficiency of the glass production when used in the working tanks and the
forehearths. In the predicted study; first of all, the characterizations of the Alumina Zirconia Silica and
Alpha Beta High Alumina refractory bricks and the samples of glass coming from two different glass
furnaces have been identified with XRF and XRD. After that; relative density, crushing strenghth and
refractoriness-under-load tests have been performed to evaluate the physical properties of the
refractory materials. After making basic refractory comparisons, in order to show the relationship between the refractory material and the glass; exudation, stoning and blistering tests have been
conducted. At these steps, the state of the internal surfaces of the refractory bricks have been
characterized by carrying out micro structure analyses with SEM. As a result of the conducted
investigations,it is concluded that in the production of tableware glass, the use of Alpha Beta High
Alumina refractory instead of AZS refractory will affect the overall glass production efficiency positively
by minimizing the glass defects and it will become economically more advantageous in the long run
Design of the CAM model and authoring tool
No full textStudents benefit from personalised attention; however, often teachers are unable to provide this. An Adaptive Hypermedia (AH) system can offer a richer learning experience in an educational environment, by giving personalised attention to students. On-line courses are becoming increasingly popular by means of Learning Management Systems (LSM). The aim of the GRAPPLE project is to integrate an AH with major LMS, to provide an environment that delivers personalised courses in a LMS interface. However, designing an AH is a much more complex and time-consuming task, than creating a course in a LMS. Several models and systems were developed previously, but the (re)-usability by educational authors of the adaptation remains limited. To simplify adaptive behaviour authoring for an educational author, a visual environment was selected as being most intuitive. This paper describes a reference model for authoring in a visual way and introduces an authoring tool based upon this model
Understanding the Development of Cam-Type Deformity by FE Analysis of the Immature Proximal Femur
No full textCam impingement appears to be an important factor in the development of early osteoarthritis (OA) of the hip. A Cam is generally diagnosed in young and active adults, already at the age of thirteen. Therefore, it has been suggested that excessive femoral loading during skeletal development might trigger the abnormal morphology. The goal of this research is to understand how the deformity develops. A finite element analysis is conducted to predict the stress distribution in the immature proximal femur under different loading conditions. Furthermore, the influence of the orientation of the epiphyseal plate is studied, as a Cam-type deformity is highly associated with an abnormal epiphyseal extension on the anterosuperior region. Previous studies suggested that octahedral shear stress promotes growth, while hydrostatic compressive stress inhibits growth. These mechanobiological principals are implemented to predict the bone growth rate. The position and the shape of the growth plate, as well as the loading direction highly influence the stress distribution in the proximal femur and growth plate. A medial directed load causes high compression stress in the growth cartilage in the lateral region. Endochondral growth is inhibited, which could result in a deflection of the growth plate, observed in Cam patients as epiphyseal extension. High regional stresses and osteogenic index appear in the epiphysis at the anterosuperior region when a convex growth plate is modeled. These results would support the theory that a Cam-type deformity might not be a result of endochondral growth, but the higher stresses demand local remodeling and apposition. Incorporating dynamic loading and tissue adaptation is needed to further understand how mechanical stimuli effects the epiphyseal growth and to predict morphological changes over time. Once one understands the etiological factors of cam impingement, the disorder can be treated at an early stage and the development into early osteoarthritis might be prevented.BMEBioMechanical EngineeringMechanical, Maritime and Materials Engineerin
DESIGN OF THE VALVE TRAIN MECHANISM OF AN INTERNAL COMBUSTION ENGINE WITH FOUR STROKS
No full textOtomobil motorlarının supap sisteminde kullanılan kamların profilleri
belirlenirken, gaz akış performansının yanı sıra sisteminin uzun ömürlü olması,
sessiz ve titreşimsiz çalışması, sürtünme kuvvetleri ve güç tüketiminin az olması
gibi şartlarda göz önünde bulundurulur. Akış performansının yüksek olması
supap kursunun büyük olmasını gerektirir. Sistemin uzun ömürlü olması, sessiz
ve titreşimsiz çalışması ve sürtünmelerin en aza indirilmesi ise supap kursunun
az olmasını gerektirir. Kam profilinin tasarımı her iki şartı sağlayacak bir
optimizasyondur.
Bu çalışmada, TEF 07/2006-11 projesi kapsamında imal edilmekte olan deney
motorunun kam profilleri tasarlanmış, imal edilmiş ve denenmiştir. İstatistik
değerler göz önünde bulundurularak, emme ve egzoz supapları için 6 mm' lik
bir kurs seçilmiş ve kam profilleri belirlenmiştir. Kam profilleri belirlenirken
kam yüzeyinin itici yüzeyine çift noktadan temas etmesi ve iticinin zıplamasına
sebep olacak büyüklükte ivmelerden kaçınılmıştır. Kam profilleri değiştirilerek
mümkün olan minimum yay kuvvetleri elde edilmiştir. Peugeot-406 motorunun
supap sisteminin, imal edilmekte olan prototipe adaptasyonu dinamik açıdan
araştırılmıştır. Supap kursu aynı kalmak kaydıyla açılma ve kapanma
süreçlerinin değişmesinin sistemin dinamik davranışları üzerindeki etkileri
incelenmiştir. Kam milinin hızı 4500 rpm yi geçmediği sürece supap iticisinin
kam üzerinde zıplama yapmayacağı anlaşılmıştır. Toplam açık kalma periyodu
120°, 124°, 128° ve 130° olan dört farklı kam mili imal edilerek deneysel olarak
motorun performansına etkileri araştırılmıştır.When designing the cam profiles of an automobile engine, beside the
performance of gaz flow, one should consider that the system should have a long
life-period, work client and without vibration, generate lesser friction forces and
consume lesser power. The higher flow performance requires relatively higher
valve displacement. However, for a system having long life-period, working
client and without vibration and generating lowest friction forces, a lower valve
displacement is required. Design of the cam profile is an optimization satisfying
both conditions.
In this study the cam profiles of the prototype of an Internal Combustion
Engine financially founded by the Gazi University Research Projects Unite,
were designed, manufacture and tested. By regarding the statistical values used
before, the lifts of valves were selected as 6 mm and using the classical spline
method, the cam profiles were designed. While determining the cam profiles,
double point contact of the cam surface to the follower surface and higher
accelerations causing the followers to jump off the cam were avoided. The
minimum spring force possible was obtained by changing cam profiles.
Adaptability of valve system of Peugeot-406 engine to the prototype being
constructed was investigated from dynamic point of view. Effects of variations
of valve lift and valve fall periods on the dynamic behavior of valve system was
examined under the same lift condition. It was determined that as long as the
speed of the cam shaft remains below 4500 rpm, the followers do not jumps off
the cam. Effects of open remaining periods of valves on the engine performance
was experimentally investigated by manufacturing four different cam profiles
having 120º, 124º, 128º and 130º total open remaining periods
Wound-induced rgs-CaM gets ready for counterresponse to an early stage of viral infection
No full textPlants and animals can recognize the invasion of pathogens through their perception of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). Plant PRRs identified have been exclusively receptor-like kinases/proteins (RLK/Ps), and no RLK/P that can detect viruses has been identified to date. RNA silencing (RNA interference, RNAi) is regarded as an antiviral basal immunity because the majority of plant viruses has RNA as their genomes and encode RNA silencing suppressor (RSS) proteins to counterattack antiviral RNAi. Many RSSs were reported to bind to double-stranded RNAs (dsRNAs), which are regarded as viral PAMPs. We have recently identified a tobacco calmodulin (CaM)-like protein, rgs-CaM, as a PRR that binds to diverse viral RSSs through its affinity for the dsRNA-binding domains. Because rgs-CaM seems to target RSSs for autophagic degradation with self-sacrifice, the expression level of rgs-CaM is important for antiviral activity. Here, we found that the rgs-CaM expression was induced immediately (within 1 h) after wounding at a wound site on tobacco leaves. Since the invasion of plant viruses is usually associated with wounding, and several hours are required for viruses to replicate to a detectable level in invaded cells, the wound-induced expression of rgs-CaM seems to be linked to its antiviral function, which should be ready before the virus establishes infection. CaMs and CaM-like proteins usually transduce calcium signals through their binding to endogenous targets. Therefore, rgs-CaM is a unique CaM-like protein in terms of binding to exogenous targets and functioning as an antiviral PRR
Underwater CAM photosynthesis elucidated by Isoetes genome
No full textTo conserve water in arid environments, numerous plant lineages have independently evolved Crassulacean Acid Metabolism (CAM). Interestingly, Isoetes, an aquatic lycophyte, can also perform CAM as an adaptation to low CO2 availability underwater. However, little is known about the evolution of CAM in aquatic plants and the lack of genomic data has hindered comparison between aquatic and terrestrial CAM. Here, we investigate underwater CAM in Isoetes taiwanensis by generating a high-quality genome assembly and RNA-seq time course. Despite broad similarities between CAM in Isoetes and terrestrial angiosperms, we identify several key differences. Notably, Isoetes may have recruited the lesser-known ‘bacterial-type’ PEPC, along with the ‘plant-type’ exclusively used in other CAM and C4 plants for carboxylation of PEP. Furthermore, we find that circadian control of key CAM pathway genes has diverged considerably in Isoetes relative to flowering plants. This suggests the existence of more evolutionary paths to CAM than previously recognized. © 2021, The Author(s).Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
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