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1.
The oxidation of low concentrations of hydrogen sulfide with air over activated carbon was studied over the temperature range 24-200°C using both fixed and fluid bed reactors. The predominant reaction, H2S + ½ Oa → H2O + S, was found to have an order of 0.5 with respect of H2S concentration. Activity of the catalyst decreased as the amount of sulfur deposited on it increased. Indirect evidence suggests that adsorption of water by the carbon also decreases its activity as a catalyst at lower temperatures. Values of the activation energy and the frequency factor were determined for various sulfur loadings using the fixed bed reaction system. Regeneration of the carbon loaded with sulfur was studied at temperatures between 150 and 500°C using steam as a carrier gas. Bright yellow sulfur was recovered. The regenerated carbon was shown to have its original activity. 相似文献
2.
Oznur Ozaltin Orhan Coskun Ozgur Yeniay Abdulhamit Subasi 《International journal of imaging systems and technology》2023,33(1):69-91
Classification of brain hemorrhage computed tomography (CT) images provides a better diagnostic implementation for emergency patients. Attentively, each brain CT image must be examined by doctors. This situation is time-consuming, exhausting, and sometimes leads to making errors. Hence, we aim to find the best algorithm owing to a requirement for automatic classification of CT images to detect brain hemorrhage. In this study, we developed OzNet hybrid algorithm, which is a novel convolution neural networks (CNN) algorithm. Although OzNet achieves high classification performance, we combine it with Neighborhood Component Analysis (NCA) and many classifiers: Artificial neural networks (ANN), Adaboost, Bagging, Decision Tree, K-Nearest Neighbor (K-NN), Linear Discriminant Analysis (LDA), Naïve Bayes and Support Vector Machines (SVM). In addition, Oznet is utilized for feature extraction, where 4096 features are extracted from the fully connected layer. These features are reduced to have significant and informative features with minimum loss by NCA. Eventually, we use these classifiers to classify these significant features. Finally, experimental results display that OzNet-NCA-ANN excellent classifier model and achieves 100% accuracy with created Dataset 2 from Brain Hemorrhage CT images. 相似文献
3.
The environmental community rightly recognizes global warming as one of the gravest threats to the planet. Methane (CH4), one of the greenhouse gases causing global warming, is emitted from a variety of sources and its concentration in atmosphere has increased dramatically over the last few centuries. Therefore, the increasing concentrations of methane are of special concern because of its effects on climate and atmospheric chemistry. Anthropogenic sources of methane can be collected under the titles of agriculture, energy, waste and industry on the basis of sectors. This paper aims at examining the past trends in emissions, the sources and mitigation strategies of the methane. As a result of the study, it is determined that the agricultural sector is the biggest source of methane emissions among the sectors. The energy, waste and industry follow the agricultural sources respectively. 相似文献
4.
As demand for more power increases, compression ratios, and operating temperatures keep rising. High speeds combined with
high temperatures make turbomachinery sealing applications even more challenging. In order to confirm sufficient service life
material pairs should be tested under conditions similar to engine operating conditions. This study presents high temperature
friction and wear characteristics of cobalt/nickel superalloys, Haynes 25 (51Co–10Ni–20Cr–15W), Haynes 188 (39Co–22Ni–22Cr–14W),
and Haynes 214 (75Ni–16Cr–3Fe–0.5Mn) sheets when rubbed against Hastelloy X (47Ni–22Cr–18Fe–9Mo) pins. Tests are conducted
at 25, 200, 400, and 540 °C with a validated custom design linear reciprocating tribometer. Sliding speed and sliding distance
are 1 Hz and 1.2 km, respectively. Friction coefficients are calculated with friction force data acquired from a load cell.
Wear coefficients are calculated through weight loss measurements. Results indicate that Haynes 25 (H25) has the lowest friction
coefficients at all test temperatures. Above 400 °C, H25 and Haynes 188 (H188) exhibit the best wear resistance. Protective
cobalt oxide layers are formed on the H25 and H188 at 540 °C in addition to nickel, chrome, and tungsten oxides. Although,
it has better oxidation resistance, Haynes 214 has relatively higher wear rates than other tested materials especially at
low temperatures. However, its wear performance improves beyond 200 °C. 相似文献
5.
Healthcare facilities are often complex and overwhelming for visitors, and wayfinding in healthcare facilities can be challenging. As there is an increasing number of global citizens who travel to seek medical care in another country, it is critical to make wayfinding easy for visitors who are not familiar with the language in a foreign country. Among many wayfinding aids, symbols are helpful for those visitors who have limited ability to understand written language. This study tested universal healthcare symbols in the United States, South Korea, and Turkey to compare the comprehension of symbols cross-country and identify predictors of the correct comprehension. To explore statistically significant relationships between symbol comprehension and countries, Pearson's Chi-square tests, logistic regression, and ANOVA were conducted. The test results showed that ten symbols among 14 tested have significant relationship with countries. Results of this study demonstrate that symbol comprehension can be varied significantly in different countries. 相似文献
6.
7.
Gokhan Aydin Izzet Karakurt Coskun Hamzacebi 《The International Journal of Advanced Manufacturing Technology》2014,75(9-12):1321-1330
An experimental study is carried out for modeling the rock cutting performance of abrasive waterjet. Kerf angle (KA) is considered as a performance criteria and modeled using artificial neural network (ANN) and regression analysis based on operating variables. Three operating variables, including traverse speed, standoff distance, and abrasive mass flow rate, are studied for obtaining different results for the KA. Data belonging to the trials are used for construction of ANN and regression models. The developed models are then tested using a test data set which is not utilized during construction of models. Additionally, the regression model is validated using various statistical approaches. The results of regression analysis are also used to determine the significant operating variables affecting the KA. Furthermore, the performances of derived models are compared for showing the accuracy levels in prediction of the KA. As a result, it is concluded that both ANN and regression models can give adequate prediction for the KA with an acceptable accuracy level. The compared results reveal also that the corresponding ANN model is more reliable than the regression model. On the other hand, the standoff distance and traverse speed are statistically determined as dominant operating variables on the KA, respectively. 相似文献
8.
M.I. Karamangil S. Coskun O. Kaynakli N. Yamankaradeniz 《Renewable & Sustainable Energy Reviews》2010,14(7):1969-1978
This study presents a literature review, especially in recent years, on the absorption refrigeration systems (ARSs), the currently used refrigerant–absorbent pairs and their alternatives. Additionally, in this study, the thermodynamic analysis of ARS using commonly encountered solution pairs in the literature was carried out, and a user-friendly software package including visual components was developed. The effects of operating temperatures, the effectivenesses of solution, refrigerant and solution–refrigerant heat exchangers (SHE, RHE, SRHE), and selection of working fluid pair on the system performance were examined by using the developed package. It was concluded that performances of the cycles improve with increasing generator and evaporator temperatures, but reduce with increasing condenser and absorber temperatures. The performance of system was affected from the SHE more than the RHE and SRHE. While the use of SHE improves the system COP up to 66%, RHE and SRHE have an effect of only 14% and 6%, respectively. For that reason, the SRHE may not be considered practically significant. Suitable solutions depending on operating conditions showed variations with respect to generator and evaporator temperatures. 相似文献
9.
Emine Kaya Nurbek Kakenov Hakan Altan Coskun Kocabas Okan Esenturk 《Journal of Infrared, Millimeter and Terahertz Waves》2018,39(5):483-491
Fabrication of terahertz modulators as simple devices with high modulation depth across a broad bandwidth is still very challenging. In this study, four different chemical vapor deposition grown multilayer graphene (MLG) modulators based on MLG/ionic liquid/gold sandwich structures have been investigated. Flexible substrates (PVC and PE) were chosen as host materials, and devices were fabricated with three different thicknesses. The resultant MLG devices can be operated at low voltages between 0 and 3.4 V providing nearly complete modulation between 0.2 and 1.5 THz with low insertion losses. Even with such low gate voltages, the devices have been doped significantly inducing 7–11-fold improvement in their sheet conductivities depending on device thickness. In addition, sheet conductivity has been improved more than three times as the graphene layer number increased from 30 to 100. With the demonstration of promising device performances, the proposed modulators can be potential candidates for applications in terahertz and related optoelectronic technologies. 相似文献
10.
This study proposes to use genetic algorithms for defining the topic boundaries in search of engine transaction logs. Users are interested in multiple topics during a search session, and genetic algorithms are used in this study to determine whether a search engine user has changed topics during a session. Sample data logs from FAST and Excite search engines were analyzed. The findings show that genetic algorithms are fairly successful in identifying topic continuations and shifts in search engine transaction logs. 相似文献