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21.
Y. Murat Elin Mehmet Saak 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(2):174-180
This paper presents the results of urease immobilization onto methacrylic acid–acrylamide grafted poly(ethyleneterephthalate) fibres. The graft yield strongly affected the maximum activity of the immobilized enzyme up to a value of 70·2%. Higher grafting caused a decline in urease activity and led to the degradation of the fibres. The minor changes observed in Km and Vmax demonstrated that the conformational changes existed during immobilization were not extensive. However, 70·2% methacrylic acid–acrylamide-g-fibres containing urease were more stable towards acidic and alkaline pH, high temperature and storage conditions compared with free enzyme. Apart from the increase in stability to heat inactivation, the initial enzymatic activity of the urease–fibre system remained almost unchanged even after 40 repeated assays corresponding to 10 h of operation in 4 months, indicating the excellent durability of the system. 相似文献
22.
Mehmet Ali Tan 《Analog Integrated Circuits and Signal Processing》1991,1(4):339-351
Hardware implementation of artificial neural networks has been attracting great attention recently. In this work, the analog VLSI implementation of artificial neural networks by using only transconductors is presented. The signal flow graph approach is used in synthesis. The neural flow graph is defined. Synthesis of various neural network configurations by means of neural flow graph is described. The approach presented in this work is technology independent. This approach can be applied to new neural network topologies to be proposed or used with transconductors designed in future technologies. 相似文献
23.
?erif Bahtiyar Mehmet Ufuk Ça?layan 《Journal of Network and Computer Applications》2012,35(1):480-490
The issue of trust is a research problem in emerging open environments, such as ubiquitous networks. Such environments are highly dynamic and they contain diverse number of services and autonomous entities. Entities in open environments have different security needs from services. Trust computations related to the security systems of services necessitate information that meets needs of each entity. Obtaining such information is a challenging issue for entities. In this paper, we propose a model for extracting trust information from the security system of a service based on the needs of an entity. We formally represent security policies and security systems to extract trust information according to needs of an entity. The formal representation ensures an entity to extract trust information about a security property of a service and trust information about whole security system of the service. The proposed model is applied to Dental Clinic Patient Service as a case study with two scenarios. The scenarios are analyzed experimentally with simulations. The experimental evaluation shows that the proposed model provides trust information related to the security system of a service based on the needs of an entity and it is applicable in emerging open environments. 相似文献
24.
The kernelized fuzzy c-means algorithm uses kernel methods to improve the clustering performance of the well known fuzzy c-means algorithm by mapping a given dataset into a higher dimensional space non-linearly. Thus, the newly obtained dataset is more likely to be linearly seprable. However, to further improve the clustering performance, an optimization method is required to overcome the drawbacks of the traditional algorithms such as, sensitivity to initialization, trapping into local minima and lack of prior knowledge for optimum paramaters of the kernel functions. In this paper, to overcome these drawbacks, a new clustering method based on kernelized fuzzy c-means algorithm and a recently proposed ant based optimization algorithm, hybrid ant colony optimization for continuous domains, is proposed. The proposed method is applied to a dataset which is obtained from MIT–BIH arrhythmia database. The dataset consists of six types of ECG beats including, Normal Beat (N), Premature Ventricular Contraction (PVC), Fusion of Ventricular and Normal Beat (F), Artrial Premature Beat (A), Right Bundle Branch Block Beat (R) and Fusion of Paced and Normal Beat (f). Four time domain features are extracted for each beat type and training and test sets are formed. After several experiments it is observed that the proposed method outperforms the traditional fuzzy c-means and kernelized fuzzy c-means algorithms. 相似文献
25.
An artificial neural network model for the effects of chicken manure on ground water 总被引:1,自引:0,他引:1
Erdal KaradurmusMustafa Cesmeci Mehmet Yuceer Ridvan Berber 《Applied Soft Computing》2012,12(1):494-497
In the areas where broiler industry is located, poultry manure from chicken farms could be a major source of ground water pollution, and this may have extensive effects particularly when the farms use nearby ground water as their fresh water supply. Therefore the prediction the extent of this pollution, either from rigorous mathematical diffusion modeling or from the perspective of experimental data evaluation bears importance. In this work, we have investigated modeling of the effects of chicken manure on ground water by artificial neural networks. An ANN model was developed to predict the total coliform in the ground water well in poultry farms. The back-propagation algorithm was employed for training and testing the network, and the Levenberg-Marquardt algorithm was utilized for optimization. The MATLAB 7.0 environment with Neural Network Toolbox was used for coding. Given the associated input parameters such as the number of chickens, type of manure pool management and depth of well, the model estimates the possible amount of total coliform in the wells to a satisfactory degree. Therefore it is expected to be of help in future for estimating the ground water pollution resulting from chicken farms. 相似文献
26.
Domes are elegant and economical structures used in covering large areas. They are built in various forms. According to their
form, they are given special names such as lamella, network, and geodesic domes. In this paper, optimum topological design
algorithm is presented that determines the optimum number of rings, the optimum height of crown and tubular section designations
for the member groups of these domes. The design algorithm developed has a routine that generates the data required for the
geometry of these domes automatically. The minimum weight of each dome is taken as the objective function. The design constraints
are implemented according to the provision of LRFD-AISC (Load and Resistance Factor Design–American Institute of Steel Constitution).
The optimum topological design problem that considers these constraints turns out to be discrete programming problem. Improved
harmony search algorithm is suggested to determine its optimum solution. The design algorithm also considers the geometric
nonlinearity of these dome structures. Design examples are presented to demonstrate the effectiveness and robustness of the
design optimization algorithm developed. 相似文献
27.
The crystallography and the interface structure of a unidirectionally solidified Cu-MgCu2 eutectic alloy have been examined by transmission electron microscopy. The microstructure of the eutectic was found to be lamellar and regularly interrupted by faults. The preference of the particular orientation relationship
could not be explained by relative atomic densities of the planes comprising the interface. Based on the defect contrast observed and extinction distance calculations, it is suggested that the fine array of defects observed at the interface may be characterized as steps with step vectors parallel to
or
Dislocations were also observed at the interface but they were rarely regular. 相似文献
28.
Acar Seda Bekin Tasdelen Mehmet Atilla Karaagac Bagdagul 《Iranian Polymer Journal》2021,30(7):697-705
Iranian Polymer Journal - The addition of methacrylate-functional polyhedral oligomeric silsesquioxane (MA-POSS) nanoparticles to styrene-butadiene rubber (SBR) composites was evaluated in terms of... 相似文献
29.
Xuejun Ye Daniel Chen Kuyen Li Vivek Shah Mehmet Kesmez Kayzad Vajifdar 《Chemical Engineering Communications》2007,194(3):368-381
We have synthesized an annealed porous aerogel titania (LUAG2), which demonstrates a very high photocatalytic activity for aldehydes and perchloroethylene (PCE) photocatalytic oxidation (PCO) in gas phase under blacklight and fluorescent light irradiation. LUAG2 has a BET surface area of 237 m2/g and a porosity of 0.31 (volume fraction). X-ray diffraction (XRD) analysis shows LUAG2 is nearly pure anatase. It has improved the destruction of PCE and aldehydes as a group by 10-34% with black light compared to Degussa P-25. The optimum water vapor to butyraldehyde molar ratio is around 1/3. LUAG2 also shows better mineralization to CO2 than Degussa P-25 TiO2 does. Under irradiation of a 4 W fluorescent lamp LUAG2 gives a consistently higher conversion than that of Degussa P-25. The highly active photocatalyst indicates potential applications in indoor and outdoor environmental pollution control. A visible-light-responsive TiO2, NTB 200, is also investigated for comparison purposes. 相似文献
30.
The graft copolymerization of methacrylic acid onto poly(ethylene terephthalate) fibers, by the aid of benzoyl peroxide, have been investigated. The graft yield increased up to 85°C, and then decreased with the further increase in temperature. The maximum graft yield was obtained at benzoyl peroxide concentration of 4.0 × 10?3 mol/L. The increase in the concentration of monomer was found to increase the graft yield. The change in the graft yield was followed by the experiments carried out using different water/solvent mixtures. Also, the change in the properties of polye (thylene terephthalate) fibers grafted with methacrylic acid such as moisture regain, density, and diameter were investigated. 相似文献