Experimental Heat Transfer Analysis from Helical Coiled Tubes with the Same Surface Area

Helical coiled tubes are commonly used in water storage tanks. In this study, an experimental investigation was carried out to obtain the heat transfer characteristics of different geometric dimensions of helical tubes under steady state conditions. Helical coiled tubes of different geometric dimensions with the same overall length and total surface area were fabricated from the same copper tubes. The helical coiled tubes were placed in a hot water tank which could be adjusted to different water temperatures. Cold water was pumped into the helical coiled tubes at different flow rates at 20 °C. The experiments were carried out for laminar flow in the range of Re numbers between 3394 and 8332. The helical coiled tube Nu number was determined and compared with the literature. Then, the effectiveness of the helical coiled tubes was calculated using the ε-NTU method

Experimental Investigation of PV Panel Performance by Using PCM with Different Fin Geometries

During the photovoltaic (PV) conversion process, a significant amount of solar radiation is converted into heat, which increases the cell\u27s temperature and reduces its efficiency. A system consisting of PCM and aluminium fins was developed to minimise power loss due to temperature increments. Using PCM as heat absorbers in this study, heat from photovoltaic panels was transferred more efficiently with aluminium fins. The PV panel temperature is regulated by this method in hot climates as a passive cooling method. To regulate the surface temperature of PV panels, RT28HC was used as PCM. The reference PV panel was compared with a container-integrated PV panel with PCM and flat aluminium fins and a container-integrated PV panel with PCM and perforated aluminium fins to regulate the temperature of the PV cells and improve the efficiency of the panels. In the laboratory, with an initial ambient temperature of 20 °C, an experiment was conducted for 60 minutes. The results of the experiment show that the average surface temperature of the PV panel decreased by 8.32 °C from 49.24 °C to 40.92 °C with flat fins and by 8.55 °C from 49.24 °C to 40.69 °C with perforated fins. The maximum electric power generation by the PV panels increased by 7.43 % compared to the usual PV panels from 1.48 W to 1.59 W with flat fins and by 9.46 % from 1.48 W to 1.62 W with perforated fins as the surface temperature of the PV panels decreased. The surface temperature and generated current, voltage, and power of the uncooled and cooled PV panels are plotted over time in this study

Design Principles of the Hospital Clean Rooms

Clean rooms can be defined as areas that are specifically controlled for particulate and microbial contamination and where they are constructed and used to reduce the number of infectious disease agents settling and multiplying and accessing from outside. In this study, the design and implementation of the air conditioning system in accordance with international standards, in particular DIN 1946-4, has been explained for an operating room in hospitals which is in the clean room and has the highest risk of infection. The tasks of physicians, engineers and architects in operating room design were mentioned and finally the cleaning, testing, adjustment and balancing (TAB) and validation process of the air conditioning system were mentioned. In particular, the risks of infections that may arise during the surgical intervention in the operating room and its relation to the air conditioning system have been mentioned and it has been emphasized that the biggest responsibility for hospital infections falls to engineers and architects, especially doctors and medical staff

Experimental modeling for hot rolling system

Bu çalışma iki kısımdan oluşmaktadır. İlk olarak, sıcak haddeleme prosesinde haddeleme kuvveti, momenti, kütük sıcaklığı ve hadde sıçraması için deneysel modelleme yapıldı. Basamak cevabı formunda olan bu modelde haddeleme kuvveti ve momenti için paso, giriş sıcaklığı, kütük genişliği, hadde çapı ve karbon eşdeğeri; kütük sıcaklığı için giriş sıcaklığı ve enerji; hadde sıçraması için de paso, kuvvet ve kütük genişliğini kullanarak daimi rejim değerlerini hesaplamaktadır. İkinci olarak, dinamik model ile sıcak haddeleme proseslerinde yaygın olarak kullanılan ve katlı lineer regresyon yöntemini kullanan klasik ampirik modeller karşılaştırıldı. Modelleri geliştirmek için kullanılan veriler, Ereğli Demir Çelik Fabrikaları 2. sıcak haddehanesi tersinir kaba haddeleme tezgahından sağlanmıştır.Anahtar Kelimeler: Deneysel modelleme, tanılama, sıcak haddeleme.This study consists of two parts: In the first part, experimental roll force, torque, slab temperature and roll deflection modeling of a plate hot-rolling is represented. The structures of these models are the step-response forms and predict the steady-state values of roll force, torque, temperature and deflection. In this study; for roll force and roll torque models; draft, temperature, slab width, roll diameter, carbon equivalent, for temperature model; temperature and energy, for deflection model; draft, roll force and slab width are used as input. The step response model parameters are estimated via recursive least square (RLS) estimation algorithm by using input information related to the past. In the second part, the proposed dynamical models are compared with the classical empiric models commonly used by several author in the rolling practice. It has included mathematical models relating rolling force and torque to the deformation resistance of the work piece in the roll gap; models of heat transfer via radiation, convection and conduction processes and for the deflection model rolling mill force and slab width are used. For empiric model, Sims’ formulae, in discrete-time form with multiple linear regressions method is used. The experimental data obtained from Ereğli Iron and Steel Factory was used for developing both of the models.Keywords: Experimental modeling, identification, hot rolling process

Assessment of procedure related anxiety and depression in oncologic patients before F-18 FDG PET-CT imaging

Background: The aim of this study was to study objectively the level of anxiety and depression in patients undergoing positron emission tomography-computed tomography (PET-CT).One hundred and forty four oncologic out-patients (76 male, 68 female) were included in this study. Methods: All patients were referred to Nuclear Medicine Department for Fluorine-18 fluorodeoxyglucose (F-18 FDG) PET-CT imaging for the assessment of their malignant or possibly malignant diseases. The Hospital Anxiety Depression Scale and the State and Trait Anxiety Inventory I and II were used to evaluate the anxiety and depression levels in these patients. Results: The mean anxiety and depression scores of The Hospital Anxiety Depression Scale prior to F-18 FDG PET-CT were 9.2 ( ± 3.8) and 6.6 ( ± 3.4), respectively. The mean state and trait anxiety scores of the State and Trait Anxiety Inventory I and II prior to F-18 FDG PET-CT were 40.4 (± 8.5) and 46.62 ± 7.8, respectively. The Hospital Anxiety Depression Scale and the State and Trait Anxiety Inventory I and II anxiety scores were found to be significantly higher in female patients, smokers and in patients with higher stage disease. Conclusion: Our results suggest that F-18 FDG PET-CT imaging may at least contribute to patient's baseline anxiety which is already generated by being an oncology patient, and thus nuclear medicine physicians should handle the patients with extra care to minimize this affect. © 2015, Umut Elboga, et al

Effects of Tooth Brushing and MouthWashing on Leaching Bisphenol A Levels From an Orthodontic Adhesive: An In Vitro Study

Objective: To assess the levels of bisphenol A (BPA) released from an orthodontic adhesive with respect to the effects of tooth brushing and mouth washing.Methods: Three groups, each containing fifteen adhesive samples were prepared. In Group 1, samples were polymerized according to manufacturer instructions. In Group 2, after the same polymerization protocol, each sample was brushed with a fluoride-containing toothpaste. For Group 3, samples were immersed in a mouth washing solution after polymerization. Later, all samples were placed into glass tubes containing 5 mL distilled water. High-performance liquid chromatography (HPLC) measurements were performed to assess the leaching amount of BPA. Intergroup comparison was performed by one way ANOVA test.Results: Mean amounts of BPA were found to be 0.2674 μg/L, 0.2692 μg/L, and 0.2705 μg/L, respectively. Only a significant difference was found between Group 1 and 3 (P < .01), revealing higher BPA levels with the mouth washing solution.Conclusion: Measurable amounts of BPA release were observed in all groups of orthodontic adhesive samples, but the detected amounts were below the toxic levels. From a clinical point of view, alcohol-containing mouth washing solutions might increase the amount of leaching monomer, since alcohol is solvent of BPA

Use of complementary and alternative medicines by a sample of Turkish women for infertility enhancement: a descriptive study

<p>Abstract</p> <p>Background</p> <p>Infertility patients are a vulnerable group that often seeks a non-medical solution for their failure to conceive. World-wide, women use CAM for productive health, but only a limited number of studies report on CAM use to enhance fertility. Little is known about traditional and religious forms of therapies that are used in relation to conventional medicine in Turkey. We investigated the prevalence and types of complementary and alternative medicine (CAM) used by infertile Turkish women for fertility enhancement.</p> <p>Methods</p> <p>A face-to-face questionnaire inquiring demographic information and types of CAM used for fertility enhancement were completed by hundred infertility patients admitted to a primary care family planning centre in Van, Turkey between January and July 2009.</p> <p>Results</p> <p>The vast majority of infertile women had used CAM at least once for infertility. CAM use included religious interventions, herbal products and recommendations of traditional "hodja's" (faith healers). Of these women, 87.8% were abused in the last 12 months, 36.6% felt not being supported by her partner and 80.5% had never spoken with a physician about CAM.</p> <p>Conclusions</p> <p>Infertile Turkish women use complementary medicine frequently for fertility enhancement and are in need of information about CAM. Religious and traditional therapies are used as an adjunct to, rather than a substitute for, conventional medical therapy. Physicians need to approach fertility patients with sensitivity and should be able to council their patients about CAM accordingly.</p