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排序方式: 共有159条查询结果,搜索用时 15 毫秒
41.
RD Bolton MD Cooper JS Frank AL Hallin PA Heusi CM Hoffman GE Hogan FG Mariam HS Matis RE Mischke LE Piilonen VD Sandberg GH Sanders U Sennhauser R Werbeck RA Williams SL Wilson R Hofstadter EB Hughes MW Ritter D Grosnick SC Wright VL Highland J McDonough 《Canadian Metallurgical Quarterly》1988,38(7):2077-2101
42.
Dalia A. Mohanna Zeyad H. Al-Sowygh Mohamed Ibrahim Abu Hasan Siti Mariam Ab Ghani Fahim Vohra 《Journal of Adhesion Science and Technology》2018,32(10):1055-1065
The study aimed to investigate the influence of surface treatments of Y-TZP on its topography and their impact on shear bond strength (SBS) of Y-TZP to veneering porcelain. Thirty-four zirconia cubes (Cercon) (10 × 10 × 10 mm3) were divided randomly into 3 groups (n = 11) according to the different surface treatments, Silica Coating (SC); Hot Solution Etching (HE); and Heat Treatment after porcelain glaze and powder application (GP). Porcelain application (IPs e.max) was performed after surface treatment using a standardized technique. Porcelain application (Ceramco-3) was also performed on 10 metal cubes (I BOND 2) as controls (MC). Specimens were subjected to thermocycling (5–55 °C, 20,000 cycles) followed by SBS testing in a universal testing machine. Surface topography was assessed by scanning electron microscopy and surface roughness (Image J). SC developed significantly higher SBS (42.10 ± 5.84 MPa) of Y-TZP to veneering ceramics compared to treatment by HE (24.0 ± 6.4 MPa), GP (23.30 ± 4.72), and the MC (29.3 ± 5.4 MPa) control (p < 0.05). SBS among HE, GP and MC specimens was comparable (p > 0.05). Y-TZP specimens treated with SC and HE showed high surface roughness compared to GP. Silicoating of Y-TZP prior to veneering can potentially reduce the high failure rates of zirconia-based restorations by enhancing the chemical bond between the core and the veneer materials. 相似文献
43.
With the rapidly escalating use of smart devices and fraudulent transaction of users data from their devices, efficient and reliable techniques for authentication of the smart devices have become an obligatory issue. This paper reviews the security risks for mobile devices and studies several authentication techniques available for smart devices. The results from field studies enable a comparative evaluation of user-preferred authentication mechanisms and their opinions about reliability, biometric authentication and visual authentication techniques. 相似文献
44.
Mariam Zomorodi‐moghadam Moloud Abdar Zohreh Davarzani Xujuan Zhou Pawel Pawiak U.Rajendra Acharya 《Expert Systems》2021,38(1)
Coronary artery disease (CAD) is one of the major causes of mortality worldwide. Knowledge about risk factors that increase the probability of developing CAD can help to understand the disease better and assist in its treatment. Recently, modern computer‐aided approaches have been used for the prediction and diagnosis of diseases. Swarm intelligence algorithms like particle swarm optimization (PSO) have demonstrated great performance in solving different optimization problems. As rule discovery can be modelled as an optimization problem, it can be mapped to an optimization problem and solved by means of an evolutionary algorithm like PSO. An approach for discovering classification rules of CAD is proposed. The work is based on the real‐world CAD data set and aims at the detection of this disease by producing the accurate and effective rules. The proposed algorithm is a hybrid binary‐real PSO, which includes the combination of categorical and numerical encoding of a particle and a different approach for calculating the velocity of particles. The rules were developed from randomly generated particles, which take random values in the range of each attribute in the rule. Two different feature selection methods based on multi‐objective evolutionary search and PSO were applied on the data set, and the most relevant features were selected by the algorithms. The accuracy of two different rule sets were evaluated. The rule set with 11 features obtained more accurate results than the rule set with 13 features. Our results show that the proposed approach has the ability to produce effective rules with highest accuracy for the detection of CAD. 相似文献
45.
Mariam Kalakech Philippe Biela Denis Hamad Ludovic Macaire 《Neural Processing Letters》2013,38(2):155-175
Semi-supervised context characterized by the presence of a few pairs of constraints between learning samples is abundant in many real applications. Analysing these instance constraints by recent spectral scores has shown good performances for semi-supervised feature selection. The performance evaluation of these scores is generally based on classification accuracy and is performed in a ground truth context. However, this supervised context used by the evaluation step is inconsistent with the semi-supervised context in which the feature selection operates. In this paper, we propose a semi-supervised performance evaluation procedure, so that both feature selection and clustering steps take into account the constraints given by the user. In this way, the selection and the evaluation steps are performed in the same context which is close to real life applications. Extensive experiments on benchmark datasets are carried out in the last section. These experiments are performed using a supervised classical evaluation and the semi-supervised proposed one. They demonstrate the effectiveness of feature selection based on constraint analysis that uses both pairwise constraints and the information brought by the unlabeled data. 相似文献
46.
47.
Fabrication of superhydrophobic unplasticized poly(vinyl chloride)/nanosilica sheets using Taguchi design methodology 下载免费PDF全文
Amir Zalnezhad Sanazgoli Javanbakht Mariam Darestani Alireza Shakeri 《Polymer International》2017,66(5):672-678
This study introduces a relatively simple technique for the manufacture of superhydrophobic coatings on polymeric surfaces. Plastics such as unplasticized poly(vinyl chloride) (UPVC ) do not have a strong hydrophobic nature that is characterized by their low contact angles. Techniques of both increasing surface roughness and lowering surface energy are required to change their hydrophilicity to superhydrophobicity. In the present study, a coating of a low‐surface‐energy thermoplastic polyurethane (TPU ) was spin‐coated with chemically treated nanosilica to reduce the surface energy of UPVC . Nanosilica particles were embedded on the surface using a hot‐press. Taguchi design was used to optimize multiple processing parameters. Samples spin‐coated with 10 g L?1 nanosilica suspension in ethanol at a rate of 400 rpm for 5 s and then hot‐pressed at 155 °C under 2 atm (203 kPa ) for 4 min had a contact angle of ca 157° and sliding angle of ca 6°, which are characteristic of superhydrophobic surfaces. Atomic force microscopy (AFM) and scanning electron microscopy (SEM ) imaging showed that these superhydrophobic surfaces were highly rough with nanoscale features. Peel test and SEM analysis showed that silica nanoparticles embedded in the TPU coating were more stable than particles immobilized on UPVC sheet without TPU coating, proving that a layer of more flexible coating can improve the longevity of superhydrophobic surfaces manufactured using this facile method. © 2016 Society of Chemical Industry 相似文献
48.
Abstract
A green protocol for the synthesis of 4,6-disubstituted-3-cyano-2-pyridones from cyanoacetamides and 1,3-dicarbonyl compounds or chalcones using guanidine based ionic liquid as catalyst has been developed. In solvent-free conditions at 30 °C, [TMG][Lac] (1,1,3,3-tetramethylguanidine lactate) was found to have the highest catalytic activity among the ionic liquids including [TMG][Ac] (1,1,3,3-tetramethylguanidine acetate), [TMG][Pr] (1,1,3,3-tetramethylguanidine propionate), [TMG][n-Bu] (1,1,3,3-tetramethylguanidine n-butyrate) and [TMG][TFA] (1,1,3,3-tetramethylguanidine trifluoroacetate). The catalyst was recovered and recycled several times without significant loss of catalytic activity. 相似文献49.
Samwel Victor Manyele Miya Peay & Mariam Rajabu Halfani 《International Journal of Food Science & Technology》2008,43(6):1058-1065
This paper presents a study on treatment of beverage‐processing wastewater (BPWW) in a three‐phase fluidised bed bioreactor (TPFBB). Wastewater samples were introduced in the TPFBB and aerated at optimum liquid and gas flow rates while measuring wastewater parameters [pH, chemical oxygen demand (COD), total suspended solids (TSS), total Kjehldahl nitrogen (TKN) and ammonia‐nitrogen (NH3‐N)]. Two different initial pH levels were studied, i.e. 9.0 and 11.5. The pH of the wastewater was observed to level off at 9.3 after 1 day. The TSS dropped by 95% after 5 days, for both initial pH levels. The NH3‐N and TKN dropped to similar final concentration independent of initial pH. The COD removal efficiency was observed to depend on the initial pH level. A highest efficiency of 98% and lowest efficiency of 50% were observed at initial pH of 9.0 and 11.5, respectively. The study results show that TPFBB is capable of treating food‐processing wastewater under suitable conditions. 相似文献
50.
Samer Mohamed Hijazi Omar Mohamed Badr A. Abdelsalam Essam M. Amer Mariam A. Yacoub Ibrahim H. Attia Yasser A. Bernhardt Heinz 《Clean Technologies and Environmental Policy》2022,24(3):815-827
Clean Technologies and Environmental Policy - Bioplastics are alternatives of conventional petroleum-based plastics. Bioplastics are polymers processed from renewable sources and are biodegradable.... 相似文献