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排序方式: 共有272条查询结果,搜索用时 15 毫秒
1.
Engineers of the concrete technology are increasingly concerned with the material passing through a sieve of the size under 0.149 mm. Materials called very fine aggregate or mineral filler may affect the performance of concrete in an either positive or a negative way. Discussions on aggregate containing very fine material are vitally important. Washing the aggregate residue has been the sole way to solve this matter to date. This is mainly based on the debatable opinion that materials of this kind are regarded as clay material. The goal of the study was to determine how the content of mineral filler might affect properties of concrete. Two types of aggregates with different amounts of cement and mineral filler were used. Basically, mineral filler replaced sand. The effect of applying different amounts of mineral filler on concrete was then determined. The addition of 7-10% of mineral filler to fine aggregate (0-2 mm) was found to considerably improve the properties of concrete. 相似文献
2.
Yassine Slimani Sagar E. Shirsath Essia Hannachi Munirah A. Almessiere Moustafa M. Aouna Nouf E. Aldossary Ghulam Yasin Abdulhadi Baykal Bekir Ozçelik Ismail Ercan 《Journal of the American Ceramic Society》2021,104(11):5648-5658
Two phase-based nanocomposites consisting of dielectric barium titanate (BaTiO3 or BTO) and magnetic spinel ferrite Co0.5Ni0.5Nb0.06Fe1.94O4 (CNNFO) have been synthesized through solid state route. Series of (BaTiO3)1-x + (Co0.5Ni0.5Nb0.06Fe1.94O4)x nanocomposites with x content of 0.00, 0.25, 0.50, 0.75, and 1.00 were considered. The structure has been examined via X-rays diffraction (XRD) and indicated the occurrence of both perovskite BTO and spinel CNNFO phases in various nanocomposites. A phase transition from tetragonal BTO structure to cubic structure occurs with inclusion of CNNFO phase. The average crystallites size of BTO phase decreases, whereas that for the CNNFO phase increases with increasing x in various nanocomposites. The morphological observations revealed that the porosity is highly reduced, and the connectivity between grains is enhanced with increasing x content. The optical properties have been investigated by UV−vis diffuse reflectance spectroscopy. The deduced band gap energy (Eg) value is found to reduce with increasing the content of spinel ferrite phase. The magnetic as well as the dielectric properties were also investigated. The analysis showed that CNNFO ferrite phase greatly affects the magnetic properties and dielectric response of BTO material. The obtained findings can be useful to enhance the performances of magneto-dielectric composite-based systems. 相似文献
3.
Nedim Muzoğlu Ahmet Mesrur Halefoğlu Muhammed Onur Avci Melike Kaya Karaaslan Bekir Sıddık Binboğa Yarman 《Expert Systems》2023,40(1):e13141
Since the first case of COVID-19 was reported in December 2019, many studies have been carried out on artificial intelligence for the rapid diagnosis of the disease to support health services. Therefore, in this study, we present a powerful approach to detect COVID-19 and COVID-19 findings from computed tomography images using pre-trained models using two different datasets. COVID-19, influenza A (H1N1) pneumonia, bacterial pneumonia and healthy lung image classes were used in the first dataset. Consolidation, crazy-paving pattern, ground-glass opacity, ground-glass opacity and consolidation, ground-glass opacity and nodule classes were used in the second dataset. The study consists of four steps. In the first two steps, distinctive features were extracted from the final layers of the pre-trained ShuffleNet, GoogLeNet and MobileNetV2 models trained with the datasets. In the next steps, the most relevant features were selected from the models using the Sine–Cosine optimization algorithm. Then, the hyperparameters of the Support Vector Machines were optimized with the Bayesian optimization algorithm and used to reclassify the feature subset that achieved the highest accuracy in the third step. The overall accuracy obtained for the first and second datasets is 99.46% and 99.82%, respectively. Finally, the performance of the results visualized with Occlusion Sensitivity Maps was compared with Gradient-weighted class activation mapping. The approach proposed in this paper outperformed other methods in detecting COVID-19 from multiclass viral pneumonia. Moreover, detecting the stages of COVID-19 in the lungs was an innovative and successful approach. 相似文献
4.
Differentiating types of muscle movements using a wavelet based fuzzy clustering neural network 总被引:1,自引:1,他引:0
Abstract: The electromyographic signals observed at the surface of the skin are the sum of many small action potentials generated in the muscle fibres. After the signals are processed, they can be used as a control source of multifunction prostheses. The myoelectric signals are represented by wavelet transform model parameters. For this purpose, four different arm movements (elbow extension, elbow flexion, wrist supination and wrist pronation) are considered in studying muscle contraction. Wavelet parameters of myoelectric signals received from the muscles for these different movements were used as features to classify the electromyographic signals in a fuzzy clustering neural network classifier model. After 1000 iterations, the average recognition percentage of the test was found to be 97.67% with clustering into 10 features. The fuzzy clustering neural network programming language was developed using Pascal under Delphi. 相似文献
5.
Thermoelectric power generators are one of the promising green energy sources. The operating and the generator parameters influence the generator output performance. In the present study, the influence of the operating and the generator parameters on the maximum output power and the efficiency of the thermoelectric power generator are examined. The output power corresponding to the maximum efficiency and the maximum attainable output power of the generator are compared. It is found that the maximum power of the thermoelectric generator corresponding to the high Figure of Merit is very sensitive to the operating temperature. The maximum power attainable is larger than that its counterpart corresponding to the maximum generator efficiency. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
6.
7.
Ozan Tas Ulku Ertugrul Mecit Halil Oztop Bekir Gokcen Mazi 《International Journal of Food Science & Technology》2021,56(11):5461-5470
Modification of food proteins to have improved functional properties is of great importance. In this study, modification of soy protein isolate (SPI) was achieved through glycation. SPI was glycated in a spray dryer (SD) and an incubator followed by freeze drying (FD). d -Allulose, an important rare sugar, was used in SPI glycation as the carbohydrate source, and results were compared with fructose. In addition to the sugar type, two different SPI powder: sugar ratios (1:1 and 5:1) were investigated. For the glycated samples, emulsification activity, free amino groups, protein solubility, Fourier-transform infrared spectroscopy analysis, antioxidant activity experiments and time-domain NMR relaxometry measurements for hydration were conducted. According to the results, the solubility of SPI that is limited in native form has shown a significant improvement after glycation through both FD and SD methods. Besides, glycation through the FD method was found to be more favourable due to its milder conditions than the SD method. Considering the physicochemical properties, the best combination for the highest glycation degree was found to be the samples prepared at the 1:1 ratio with d -Allulose in the FD method. Overall, it was concluded that glycation of SPI enhanced its functional properties such as antioxidant and emulsification activities. 相似文献
8.
Yasemin Arslan Udum Hüseyin Bekir Yıldız Hacer Azak Elif Sahin Oktay Talaz Ali Çırpan Levent Toppare 《应用聚合物科学杂志》2014,131(17)
New π‐conjugated polymers containing dithieno(3,2‐b:2′,3′‐d)pyrrole (DTP) were successfully synthesized via electropolymerization. The effect of structural differences on the electrochemical and optoelectronic properties of the 4‐[4H‐dithieno(3,2‐b:2′,3′‐d)pyrrol‐4‐yl]aniline (DTP–aryl–NH2), 10‐[4H‐dithiyeno(3,2‐b:2′,3′‐d)pirol‐4‐il]dekan‐1‐amine (DTP–alkyl–NH2), and 1,10‐bis[4H‐dithieno(3,2‐b:2′,3′‐d)pyrrol‐4‐yl] decane (DTP–alkyl–DTP) were investigated. The corresponding polymers were characterized by cyclic voltammetry, NMR (1H‐NMR and 13C‐NMR), and ultraviolet–visible spectroscopy. Changes in the electronic nature of the functional groups led to variations in the electrochemical properties of the π‐conjugated systems. The electroactive polymer films revealed redox couples and exhibited electrochromic behavior. The replacement of the DTP–alkyl–DTP unit with DTP–aryl–NH2 and DTP–alkyl–NH2 resulted in a lower oxidation potential. Both the poly(10‐(4H‐Dithiyeno[3,2‐b:2′,3′‐d]pirol‐4‐il)dekan‐1‐amin) (poly(DTP–alkyl–NH2)) and poly(1,10‐bis(4H‐dithieno[3,2‐b:2′,3′‐d]pyrrol‐4‐yl) decane) (poly(DTP–alkyl–DTP)) films showed multicolor electrochromism and also fast switching times (<1 s) in the visible and near infrared regions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40701. 相似文献
9.
Heat treatment is a well-known method for modifying wood that is applied in different ways, and treatment schedules change from tree to tree. This treatment improves the physical properties of wood but, in general, it reduces the mechanical properties of wood. The effects of heat treatment on the mechanical properties of juvenile and mature wood of the same tree species have not been well-defined. Therefore, we focused our study on the differences in the mechanical properties of juvenile wood and mature wood of Eucalyptus grandis after both were subjected to heat treatment. Wood samples were treated at temperatures of 120, 150, and 180°C for 4, 6, and 8 h. The test results showed that decreases in the mechanical properties of juvenile wood (e.g., modulus of elasticity (MOE), modulus of rupture (MOR), compression strength (CS), and impact bending (IB)) were greater than the decreases that occurred in mature wood that was heat treated at the same conditions. 相似文献
10.
Four different mercaptoalkyl-substituted calixarene derivatives (5,11,17,23-tetra-tert-butyl-25,27-bis(3-mercaptopropoxyl)-26,28-dihydroxycalix[4]arene, 25,27-bis(3-mercaptopropoxyl)-26,28-dihydroxycalix[4]arene, 25,27-bis(5-mercaptopentanoxyl)-26,28-dihydroxycalix[4]arene and 5,17-di-tert-butyl-11,23-di-carboxyl-26,28-bis(3-mercaptopropoxyl)-25,27-di-hydroxycalix[4]arene) were synthesized. Their structures were characterized by Fourier transform infrared spectroscopy (FTIR), 1H and 13C NMR spectroscopy, and elemental analysis techniques. Moreover, their extraction capabilities at different parameters such as pH, shaking speed, and shaking time were examined toward dichromate ions. Results implied that all mercaptoalkyl-substituted calixarene derivatives showed an extraction capability toward dichromate anion while the carboxyl-functionalized calixarene-marcapto-alkyl derivative exhibited the highest extraction capability. 相似文献