Otobüslerde Kullanılan Plastik Yakıt Tanklarının Statik Ve Dinamik Analizler Yardımıyla Dayanımının İncelenmesi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Günümüzde, otobüslerde kullanılmakta olan konvansiyonel metal yakıt tankları yerini plastik yakıt tanklarına bırakmaktadır. Bu makalede, plastik yakıt tanklarının, statik ve dinamik analizlere dayalı, bilgisayar destekli, geliştime-tasarım projesinn bir kısmı sunulmuştur. Öncelikle, plastik malzemenin mekanik özelliklerini bulmaya yönelik kupon testleri gerçekleştirilmiştir. Statik analizlerde yakıt tankına eşdeğer yükler uygulanmıştır. Dinamik analizler ise zamanla değişen yük, yakıt ve tankın atalaet momentleri göz önüne alınmış ve modal transient analiz yöntemi kullanılmıştır. Statik analizlerde, eşdeğer statik yükleme yaklaşımı kullanılmaktadır. Yapılan dinamk analizlerde, akışkan akustik elemanlar kullanılarak modellenmiştir. Yakıt tankı farklı doluluk oranları için incelenerek karşılaştırılmış ve sonuçları bu bildiride paylaşılmıştır.Nowadays, the conventional metal fuel tanks used in buses are being replaced with plastic fuel tanks. In this paper, a part of the project which aims to develop a computer aided methodology for developing/designing of the plastic fuel tanks based on static and dynamic analysis is presented. Coupon tests are first conducted to acquire the mechanical properties of the plastic material. In the static analysis, equivalent static loads are applied to the fuel tanks. In the dynamic analysis, the time varying loading and the inertia of the fluid and fuel tanks are taken into account using modal transient analysis. Fluid which is in the tank is modeled with acoustic approach in dynamic analysis. In this paper, different fullness ratios of the fuel tank are investigated and both results are compared each other

Monitoring the damage state of fiber reinforced composites using an FBG network for failure prediction

A structural health monitoring (SHM) study of biaxial glass fibre-reinforced epoxy matrix composites under a constant, high strain uniaxial fatigue loading is performed using fibre Bragg grating (FBG) optical sensors embedded in composites at various locations to monitor the evolution of local strains, thereby understanding the damage mechanisms. Concurrently, the temperature changes of the samples during the fatigue test have also been monitored at the same locations. Close to fracture, significant variations in local temperatures and strains are observed, and it is shown that the variations in temperature and strain can be used to predict imminent fracture. It is noted that the latter information cannot be obtained using external strain gages, which underlines the importance of the tracking of local strains internally

Prediction of self-compacting concrete elastic modulus using two symbolic regression techniques

yesThis paper introduces a novel symbolic regression approach, namely biogeographical-based programming (BBP), for the prediction of elastic modulus of self-compacting concrete (SCC). The BBP model was constructed directly from a comprehensive dataset of experimental results of SCC available in the literature. For comparison purposes, another new symbolic regression model, namely artificial bee colony programming (ABCP), was also developed. Furthermore, several available formulas for predicting the elastic modulus of SCC were assessed using the collected database. The results show that the proposed BBP model provides slightly closer results to experiments than ABCP model and existing available formulas. A sensitivity analysis of BBP parameters also shows that the prediction by BBP model improves with the increase of habitat size, colony size and maximum tree depth. In addition, among all considered empirical and design code equations, Leemann and Hoffmann and ACI 318-08’s equations exhibit a reasonable performance but Persson and Felekoglu et al.’s equations are highly inaccurate for the prediction of SCC elastic modulus

Monitoring Poisson’s Ratio Degradation of FRP Composites under Fatigue Loading Using Biaxially Embedded FBG Sensors

The significance of strain measurement is obvious for the analysis of Fiber-Reinforced Polymer (FRP) composites. Conventional strain measurement methods are sufficient for static testing in general. Nevertheless, if the requirements exceed the capabilities of these conventional methods, more sophisticated techniques are necessary to obtain strain data. Fiber Bragg Grating (FBG) sensors have many advantages for strain measurement over conventional ones. Thus, the present paper suggests a novel method for biaxial strain measurement using embedded FBG sensors during the fatigue testing of FRP composites. Poisson’s ratio and its reduction were monitored for each cyclic loading by using embedded FBG sensors for a given specimen and correlated with the fatigue stages determined based on the variations of the applied fatigue loading and temperature due to the autogenous heating to predict an oncoming failure of the continuous fiber-reinforced epoxy matrix composite specimens under fatigue loading. The results show that FBG sensor technology has a remarkable potential for monitoring the evolution of Poisson’s ratio on a cycle-by-cycle basis, which can reliably be used towards tracking the fatigue stages of composite for structural health monitoring purposes

Conceptual level FEM based wing weight estimation

textWeight and its estimation have a vital impact in the aircraft design process from the very early phases. When the conceptual design configuration of an aircraft has been created, it should ensure that the estimated weight is sufficiently accurate to meet the performance and cost requirements. The estimation of structural weight in early design stages is mostly performed using historical data; however, this approach does not provide reliable weight estimates for unconventional or unique designs or those that employ advanced materials. One solution for improving the accuracy of conceptual level weight estimation is to improve the fidelity of the methodology, geometry models, and loads through the use of Finite Element Methods (FEM). This thesis is intended to demonstrate an initial application of conceptual-level FEM based weight estimation to aircraft wing structure.Aerospace Engineering and Engineering Mechanic

Staged off-pump coronary artery bypass grafting and radical nephrectomy in a patient with multivessel coronary artery disease and a renal tumour

Coronary artery diseases and neoplastic disorders are the leading causes of morbidity and mortality in the elderly. Recently, controversial approaches have been raised about the treatment of cases with concomitant occurrence of coronary artery diseases and malignancies. The detrimental effects of cardiopulmonary bypass on neoplastic cells are always a challenge for such cases. We present a case of a large renal tumour associated with a recently symptomatic coronary artery disease which was successfully treated with staged off-pump coronary artery bypass grafting followed by radical nephrectomy. In such patients, off-pump revascularisation is favourable in order to decrease the risk of cancer spreading when compared to traditional on-pump cases. In our opinion, staged off-pump coronary arterial revascularisation followed by definitive surgical treatment for the malignancy is a safe and effective treatment modality in patients with coronary artery disease and oncological diseases

Treatment of nonsyndromic dentigerous cysts in primary dentition

Mehmet Cemal Akay, Erdem Kaya, Mert ZeytinoğluFaculty of Dentistry, Department of Oral and Maxillofacial Surgery, Ege University, Bornova, Izmir, TurkeyObjective: Dentigerous cysts are benign odontogenic cysts that are associated with the crowns of permanent teeth. They usually occur singly and are located in the mandible. Nonsyndromic bilateral dentigerous cysts (NSBDC) are rarely seen during childhood. The aim of this study was to determine the long-term effects of the marsupialization technique in growing children with NSBDC.Study design: Seven patients with NSBDC (4 female, 3 male) ranging in age from 7 to 9 years (mean 8.35 years) were involved in the study. All the individuals were treated by marsupialization. Space-maintaining appliances were applied during permanent teeth eruption. Intraoral photographs, and panoramic and periapical films were taken before surgery and during healing.Results: The NSBDC were successfully treated by the marsupialization technique and rapid healing period was observed in the growing patients, without any loss of permanent teeth. No recurrence was seen in the long-term follow-up period (3–10 years).Conclusion: Our clinical and radiological results revealed that using the marsupialization technique in children with NSBDC provided safe healing of permanent teeth around the dentigerous cysts in a short period. However, treatment planning and regular clinical follow-ups are necessary to ensure clinical success.Keywords: nonsyndromic bilateral dentigerous cysts, primary dentition, marsupializatio

Do PD-1 and PD-L2 expressions have prognostic impact in hematologic malignancies?

Background/aim: PD-1 (programmed death-1) is an immune checkpoint receptor that modulates T-cell activity in peripheral tissues via interaction with its ligands, PD-L1 (programmed death-ligand 1) and PD-L2 (programmed death-ligand 2). Tumor cells upregulate PD-L1 or PD-L2 to inhibit this T lymphocyte attack. Our goal was to determine the PD-1 and PD-L2 expression rates of various hematologic malignancies, and evaluate whether PD-1 and PD-L2 expressions have an impact on prognosis

PD-1 and PD-L2: Do they have prognostic value in lymphomas?

Objective: PD-1 (programmed death-1) is an immune checkpoint receptorthat modulates T-cell activity in peripheral tissues via interaction with itsligands, PD-L1 (programmed death-ligand 1) and PD-L2 (programmeddeath-ligand 2). Tumor cells upregulate PD-L1 or PD-L2 to dampen Tlymphocyte attack. The checkpoint inhibition by tumor cells via the PD-1pathway suppress the antitumor immune response. The role of PD-1pathway has been extensively investigated in non-hematologicmalignancies, however, the exact role of this pathway is not established inhematologic disorders. So, we aimed to demostrate the PD-1 and PD-L2expresion rate of various lymphoma subtypes, and to evaluate whether PD1 and PD-L2 expresion have impact on prognosis.Method: For this purpose, pre-treatment lymph node biopsy specimens of92 patients [25 Hodgkin lymphoma (HL) and 67 non-Hodgkin lymphoma(NHL)] have been stained with monoclonalantibody immunstains of PD-1 and PD-L2.Results: The overall expression rate of PD-1 was 76% and 82.1% in patientswith HL and NHL, respectively. PD-L2 expression rate was weak in bothHL and NHL cases. Since we have evaluated whether there is a correlationbetween immunohistochemistry (IHC) results and survival of patients withHL and NHL, we couldn’t demonstrate a meaningful evidence that thesemarkers have an impact on prognosis.Conclusions: We conclude that the role of PD-1 pathway can bedemonstrated by IHC. If IHC markers might be standardized in the future,especially a cutoff that defines a clinically significant positive andpredictive value, may help identifying patients more likely to benefit fromanti-PD-1 therapies.</p