Assessment of sustainability of structures requires calculation of life-cycle environmental and economic impacts. In this study, it is aimed to investigate economic value contribution of corrosion ...prevention, provided by galvanic cathodic protection method during the use life of marine structures, with consideration of sustainability. For a real wharf structure, cost of galvanic cathodic protection during the economic life of the structure and cost-benefit analysis of corrosion prevention are presented, and a method is proposed for understanding its economic contribution. Based on a real wharf structure's design and corrosion protection calculations, and considering a use life of approximately 50 years, average loss of material due to corrosion is 0.16 mm/year, in absence of cathodic protection. Thus, for the wharf structure under investigation (two segments each 10 m × 45 m size supported by a total of 100 piles with diameter 100 cm and depth varying between 34-40 m), loss of material is estimated for each pile as 95 kg/year, totalling 475 tons for 100 piles in 50 years. This loss may lead to strengthening requirements for the structure. Comparing costs of strengthening with 91.1 tons of Al-Zn-In anode that would be spent for cathodic protection, economic gains can be estimated as 285,000 USD.
This study aimed to compare ProGlider (Dentsply Sirona, Ballaigues, Switzerland) and R-Pilot (VDW, Munich, Germany) instruments in terms of their cyclic fatigue resistance using an artificial ...stainless steel canal showing an abrupt apical curvature, torsional resistance according to the ISO specification, and topographic changes on the instrument surface after glide path management in mesial canals of mandibular first molars with the abrupt curvature selected based on their micro–computed tomographic examination.
Eighty instruments were used: 40 ProGlider (size 0.16, .02v taper) and 40 R-Pilot (size 0.125, .04 taper) instruments. The cyclic fatigue resistance was tested in a static test model using an artificial canal with an abrupt apical curvature (angle of curvature of 90° and radius of curvature of 2 mm). The torsional resistance test was performed according to ISO 3630-1 specifications. To determine surface topography of the unused and used instruments, mesial root canals of mandibular molars with an abrupt apical curvature were selected to prepare a glide path with either the ProGlider or R-Pilot instrument. An optical profilometer and scanning electron microscopy were used to determine the surface properties. Normally distributed torsional and cyclic resistance data were analyzed using the Student t test, whereas quantitative data obtained by the optical profilometer were analyzed with the Kruskal-Wallis H test with a 5% significance threshold.
The R-Pilot showed significantly higher cyclic fatigue and torsional resistance than the ProGlider (P < .05). Angular deflection values were similar between instruments (P < .05). Measurements made from the blade area showed that the surface roughness values of the ProGlider were larger. Cutting blade measurements showed that unused instruments had significantly greater roughness values than used ones (P < .05). Although there was a 14% increase between the blade edge radii of the used and unused R-Pilot instruments, this difference was determined as 61% in ProGlider instruments.
The R-Pilot exhibited greater cyclic fatigue strength than the ProGlider when tested in an artificial canal with an inner diameter of 1.0 mm and an abrupt apical curvature. Torsional resistance of the R-Pilot was higher than the ProGlider, but the angular deflection values were similar. Glide path preparation in a mesial root canal with an abrupt apical curvature did not increase the surface roughness of both instruments but resulted in a greater blade edge radius.
This study investigates passive heat transfer enhancement techniques to determine the distribution of temperature and static pressure in test tubes, the friction factor, the heat flux, the ...temperature difference between the inlet and outlet fluid temperatures, the pressure drop penalty and the numerical convective heat transfer coefficient, and then compares the results to the experimental data of Zdaniuk et al. It predicts the single-phase friction factors for the smooth and enhanced tubes by means of the empirical correlations of Blasius and Zdaniuk et al. This study performed calculations on a smooth tube and two helically finned tubes with different geometric parameters also used in the analyses of Zdaniuk et al. It also performed calculations on two corrugated tubes in the simulation study. In Zdaniuk et al.'s experimental setup, the horizontal test section was a 2.74
m long countercurrent flow double tube heat exchanger with the fluid of water flowing in the inner copper tube (15.57–15.64
mm i.d.) and cooling water flowing in the annulus (31.75
mm i.d.). Their test runs were performed at a temperature around 20
°C for cold water flowing in the annulus while Reynolds numbers ranged from 12,000 to 57,000 for the water flowing in the inner tube. A single-phase numerical model having three-dimensional equations is employed with either constant or temperature dependent properties to study the hydrodynamics and thermal behaviors of the flow. The temperature contours are presented for inlet, outlet and fully developed regions of the tube. The variations of the fluid temperature and static pressure along tube length are shown in the paper. The results obtained from a numerical analysis for the helically tubes were validated by various friction factor correlations, such as those found by Blasius and Zdaniuk et al. Then, numerical results were obtained for the two corrugated tubes as a simulation study. The present study found that the average deviation is less than 5% for the friction factors obtained by the Fluent CFD program while Blasius's correlation has the average deviation of less than 10%. The corrugated tubes have a higher heat transfer coefficient than smooth tubes but a lower coefficient than helically finned tubes. The paper also investigates the pressure drop penalty for the heat transfer enhancement.
Geothermal water is generally used for heating another fluid and therefore heat transfer between these fluids must be as high as possible. For heat exchangers, heat transfer per unit temperature ...difference and heat capacity is defined by effectiveness of heat exchanger (ε) and capacity ratio of hot and cold streams (Cr). Effectiveness of heat exchanger decreases as capacity ratio increases. Therefore, it is desired to maximize the multiplication of effectiveness and capacity ratio to maximize heat transfer. A new model was suggested for the determination of the heat capacity ratio that provides the maximum heat transfer and best type of heat exchanger. Maximum heat transfer occurs when capacity ratio is unity and therefore ε*Cr curves given as a function of NTU (number of transfer units) for Cr = 1 for various heat exchanger types. Also, the best type of heat exchanger giving maximum heat transfer can be determined using ε*Cr curves for geothermal applications.
•Design of geothermal water heating systems for greenhouses.•Determination of heat capacity ratios that provide maximum heat transfer.•The best type of heat exchanger for geothermal water heating systems.
An increasing number of new on-set autoimmune-inflammatory rheumatic diseases (AIRD) after COVID-19 vaccination has begun to be reported in the literature. In this article, we present our patients ...with new-onset AIRD after vaccination for COVID-19 and review the literature on the subject.
We investigated the clinical characteristics and laboratory parameters of previously described "newly developed AIRD in individuals recently vaccinated for COVID-19", in 22 cases vaccinated with one of the COVID-19 vaccines (BNT162b2 or CoronaVac) approved in our country.
We collected 22 cases (14 female, 63.6%) that developed an AIRD after COVID-19 vaccination. Mean age was 53±14.4 (24-87) years. The interval between the last dose of vaccination and the development of the first complaint was 23.9±19.5 (4-90) days. CoronaVac was administered to four patients, and the BNT162b2 to 18 patients. AIRD-related symptoms developed in 12 patients after the first dose, in 8 patients after the second dose, and in two patients after the third dose. Twelve out of the 22 (54.5%) cases were diagnosed with rheumatoid arthritis, two with SLE, and the remaining eight patients each with leukocytoclastic vasculitis, Sjogren's syndrome, psoriatic arthritis, ankylosing spondylitis, systemic sclerosis, mixed connective tissue disease, eosinophilic granulomatosis with polyangiitis, and inflammatory myositis, respectively. Six patients had a history of documented antecedent COVID-19 infection.
Autoimmune/inflammatory rheumatic diseases may develop after COVID-19 vaccinations. In the era of the COVID-19 pandemic, vaccination should be questioned carefully in newly diagnosed AIRD patients.
Objective. Renal biopsy contributes to the diagnosis, follow-up, and treatment of many rheumatic conditions. This study assessed the diagnostic role and safety of renal biopsies in a tertiary ...rheumatology clinic.
Methods. Renal biopsies performed between June 2020 and December 2022 were screened, and demographic, clinical, histopathological, and safety data were collected from patient records.
Results. In this study, 33 males and 38 females were included. Except for 1 patient who received acetylsalicylic acid, antiaggregant, and/or anticoagulant drugs were stopped before the biopsy. Complications included a decrease of hemoglobin in 8 patients (11.3%) and microscopic hematuria in 40 patients (56.3%). Control ultrasonography was performed in 16 patients (22.5%), and a self-limiting hematoma was found in 4 of them (5.6%) without additional complications. While less than 10 glomeruli were obtained in 9 patients (9.9%), diagnosis success was 94.4%. Histopathological data were consistent with one of the pre-biopsy diagnoses in 54 of 67 cases (80.6%) but showed discrepancies in 19.4% (n=13) of patients. A repeat biopsy was performed in 7 patients for re-staging or insufficient biopsy.
Conclusions. Renal biopsy significantly contributes to rheumatology practice, especially in patients with complex clinical and laboratory findings or in whom different treatments can be given according to the presence, severity, and type of renal involvement. Although the possibility of obtaining insufficient tissue and the need for re-staging and repeat biopsy in the follow-up might be expected, complication risk does not seem to be a big concern. Renal biopsy often evidenced discrepancies between pre-biopsy diagnosis and histopathological findings.
Natural convection heat transfer from a horizontal cylinder is studied experimentally and numerically. Experimental study had taken place in different environmental temperature in a conditioned room ...which can be maintained at a stable required value and inside a sufficiently designed test cabin. The environmental and cylinder surface temperatures varied between 10 °C–40 °C and 20 °C–60 °C respectively. In the experimental study, two cylinders having different diameters of 4.8 mm–9.45 mm are used and constant heat flux was applied. On the basis of the experimental data, a correlation for the average Nusselt number over the cylinder is proposed in the range of 7.4 10
1
<
Ra
<
3.4 10
3. The proposed correlation is compared with the well known correlations on natural convection heat transfer from a horizontal cylinder in the specified range of Rayleigh number, and it is shown that the results are in satisfactory agreement. The problem is also investigated numerically. The experimental data and the numerical results fall in ±
20% band. The numerical results obtained in this study are also compared with the results of Merkin. The characteristics of trend lines are similar.
Natural convection heat transfer from horizontal concentric cylinders is studied experimentally and numerically. Concentric cylinders were formed with two test cylinders made of copper, and the ...annulus was filled with water. Concentric cylinder system was located in the ambient air and the inner horizontal cylinder was kept at a constant temperature. Experimental study was carried out at different ambient temperatures in a conditioned room which can be maintained at a stable required value and inside a sufficiently designed test cabin. The ambient and inner copper cylinder surface temperatures (T
∞ and T
c) varied between 20 °C–30 °C and 30 °C–60 °C respectively. Also, experiments were performed for bare cylinder at the same conditions as concentric cylinders to compare results. On the basis of the experimental data average Nusselt numbers for the air side of the concentric cylinders were calculated and compared with numerical results. The effective thermal conductivity
(
k
e
f
f
)
of the annulus was calculated by using the experimental data and numerical solution results and also compared with the well known correlation. Isotherms and streamlines are presented in the annulus and the air side for Ra
L = 9 × 10
5–5 × 10
6 and
Ra = 2 × 10
5–7 × 10
5 respectively. It is seen that numerical and experimental results are in a good agreement. Heat transfer rates under steady-state conditions from bare and concentric horizontal cylinders were compared and heat transfer enhancement was determined. Also the effect of the decrease in the temperature of the inner copper cylinder surface (condensation temperature) on COP was investigated considering an ideal Carnot refrigeration cycle. It is found that the enhancement in COP of a Carnot refrigeration cycle is 42.6% under steady-state conditions.
In refrigeration systems, it is possible to reduce energy consumption (compressor power) and increase COP by decreasing the condensation temperature. Decreasing the condensation temperature can be ...achieved either by increasing the overall heat transfer coefficient or heat transfer surface area of the condenser. Usually, the radiuses of condenser tubes of domestic refrigerators are quite smaller than the critical radius. Thus, the radius can be increased up to the critical radius by coating the bare condenser tube to increase heat transfer. On the other hand, refrigerators operate discontinuously depending on the ambient temperatures. Coating material stores some of the heat during the working period and continues heat transfer during the off period so that the condenser continues transferring heat while the compressor is not working. Storage effect depends on the specific heat and density of the coating material. Transient and steady-state natural convection heat transfer from a heated horizontal cylinder covered with concrete layer by molding is studied experimentally and numerically to determine the effects of the parameters considered above. The copper and the concrete test cylinders used in the experimental study have a length of 1 m and outer diameter of 9.45
mm and 68.5
mm respectively. The ambient and copper cylinder surface temperatures varied between 20
°C÷30
°C and 30
°C÷50
°C respectively. Constant heat flux was applied to bare and concrete cylinders. Transient heat transfer experiments were performed when bare, and concrete cylinders were reached to steady state condition. Heat transfer rates under transient conditions from bare and concrete horizontal cylinders were compared and heat transfer enhancement was determined. Based on the experimental data average Nusselt numbers were calculated and compared with the well known correlations. Also temperature distributions obtained from numerical simulations were very close to the experimental data. The effect of the decrease in the temperature of the inner copper cylinder surface (condensation temperature) on COP was investigated considering an ideal Carnot refrigeration cycle. It is found that the enhancement in COP of a Carnot refrigeration cycle is 35.7% under transient condition.
Shape reconstruction methods are particularly well suited for imaging of concealed targets. Yet, these methods are rarely employed in real nondestructive testing applications, since they generally ...require the electrical parameters of outer object as a priori knowledge. In this regard, we propose an approach to relieve two well known shape reconstruction algorithms, which are the linear sampling and the factorization methods, from the requirement of the a priori knowledge on electrical parameters of the surrounding medium. The idea behind this paper is that if a measurement of the reference medium (a medium which can approximate the material, except the inclusion) can be supplied to these methods, reconstructions with very high qualities can be obtained even when there is no information about the electrical parameters of the surrounding medium. Taking the advantage of this idea, we consider that it is possible to use shape reconstruction methods in buried object detection. To this end, we perform several experiments inside an anechoic chamber to verify the approach against real measurements. Accuracy and stability of the obtained results show that both the linear sampling and the factorization methods can be quite useful for various buried obstacle imaging problems.
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