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排序方式: 共有401条查询结果,搜索用时 16 毫秒
1.
Durmuş Burhanettin Temurtaş Hasan Özyön Serdar 《Neural computing & applications》2020,32(22):17097-17113
Neural Computing and Applications - This study presents the design of a tenth-order multiple feedback Chebyshev low-pass filter (MF-C-LPF). Component selection and gain calculation of filters are... 相似文献
2.
Serdar Akbayrak Yalçın Tonbul Saim Özkar 《International Journal of Hydrogen Energy》2021,46(27):14259-14269
Herein, we report the use of tungsten(VI) oxide (WO3) as support for Rh0 nanoparticles. The resulting Rh0/WO3 nanoparticles are highly active and stable catalysts in H2 generation from the hydrolysis of ammonia borane (AB). We present the results of our investigation on the particle size distribution, catalytic activity and stability of Rh0/WO3 catalysts with 0.5%, 1.0%, 2.0% wt. Rh loadings in the hydrolysis reaction. The results reveal that Rh0/WO3 (0.5% wt. Rh) is very promising catalyst providing a turnover frequency of 749 min?1 in releasing 3.0 equivalent H2 per mole of AB from the hydrolysis at 25.0 °C. The high catalytic activity of Rh0/WO3 catalyst is attributed to the reducible nature of support. The report covers the results of kinetics study as well as comparative investigation of activity, recyclability, and reusability of colloidal(0) nanoparticles and Rh0/WO3 (0.5 % wt. Rh) catalyst in the hydrolysis reaction. 相似文献
3.
A major task of a Web GIS (Geographic Information Systems) system is to transfer map data to client applications over the
Internet, which may be too costly. To improve this inefficient process, various solutions are available. Caching the responses
of the requests on the client side is the most commonly implemented solution. However, this method may not be adequate by
itself. Besides caching the responses, predicting the next possible requests from a client and updating the cache with responses
for those requests together provide a remarkable performance improvement. This procedure is called “prefetching” and makes
caching mechanisms more effective and efficient. This paper proposes an efficient prefetching algorithm called Retrospective
Adaptive Prefetch (RAP), which is constructed over a heuristic method that considers the former actions of a given user. The
algorithm reduces the user-perceived response time and improves user navigation efficiency. Additionally, it adjusts the cache
size automatically, based on the memory size of the client’s machine. RAP is compared with four other prefetching algorithms.
The experiments show that RAP provides better performance enhancements than the other methods. 相似文献
4.
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
5.
Journal of Intelligent Manufacturing - The order batching problem is a combinatorial optimization problem that arises in the warehouse order picking process. In the order batching problem, the aim... 相似文献
6.
With the introduction of the Regular Membership Constraint, a new line of research has opened where constraints are based
on formal languages. This paper is taking the next step, namely to investigate constraints based on grammars higher up in
the Chomsky hierarchy. We devise a time- and space-efficient incremental arc-consistency algorithm for context-free grammars,
investigate when logic combinations of grammar constraints are tractable, show how to exploit non-constant size grammars and
reorderings of languages, and study where the boundaries run between regular, context-free, and context-sensitive grammar
filtering. 相似文献
7.
In wind energy conversion systems, one of the operational problems is the changeability and discontinuity of wind. In most cases, wind speed can fluctuate rapidly. Hence, quality of produced energy becomes an important problem in wind energy conversion plants. Several control techniques have been applied to improve the quality of power generated from wind turbines. Pitch control is the most efficient and popular power control method, especially for variable-speed wind turbines. It is a useful method for power regulation above the rated wind speed. This paper proposes an artificial neural network-based pitch angle controller for wind turbines. In the simulations, a variable-speed wind turbine is modeled, and its operation is observed by using two types of artificial neural network controllers. These are multi-layer perceptrons with back propagation learning algorithm and radial basis function network. It is shown that the power output was successfully regulated during high wind speed, and as a result overloading or outage of the wind turbine was prevented. 相似文献
8.
The study of chloride‐induced corrosion started more than three decades ago, after extensive cases of damage were observed on reinforced concrete structures in coastal regions and on infrastructural objects exposed to salt action. Nowadays, the basis for sustainable concrete industry lies in these three aspects: reducing CO2 emissions by using by‐products of other industries (slag, fly ash, silica fume) for cement production, conservation of natural resources by replacing part of the aggregate with recycled construction waste, as well as use of recycled water in concrete production, and finally, construction of durable concrete structures. Durability design procedures for reinforced concrete structures in aggressive environments are still to a large extent empirical, especially in the case of using blended cements. The type of cement has a considerable effect on the properties of concrete, especially concrete resistance to the penetration of chloride ions. The paper presents results of testing durability and deformational properties of concrete produced with quaternary‐blended cement. A clearer insight into these properties is a necessary starting point for the performance‐based design of concrete prepared with blended cements, leading to more durable and corrosion‐free concrete structures in aggressive environments. 相似文献
9.
10.
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