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101.
Steel slag, which is produced locally in great amounts, has a negative impact on the environment when disposed. Local steel slag has a low CaO content and has no pozzolanic activity.In this research, local unprocessed steel slag is introduced in concrete mixes. Various mixes with compressive strength ranging from 25 to 45 MPa are studied. The slag is used as fine aggregate replacing the sand in the mixes, partly or totally. Ratios of 0%, 15%, 30%, 50% and 100% are used.Depending on the grade of concrete, the compressive strength is improved when steel slag is used for low sand replacement ratios (up to 30%).When optimum values are used, the 28-day tensile strength of concrete is improved by 1.4–2.4 times and the compressive strength is improved by 1.1–1.3 times depending on the replacement ratio and the grade of concrete. The best results are obtained for replacement ratios of 30–50% for tensile strength and 15–30% for compressive strength.Therefore, the use of steel slag in concrete would enhance the strength of concrete, especially tensile strength, provided the correct ratio is used. 相似文献
102.
Yangyang Zhang Chunlin Ji Malik W. O'Brien D. Edwards D. 《Wireless Communications, IEEE Transactions on》2009,8(9):4393-4399
In this letter, we propose a novel receive antenna selection algorithm based on cross entropy optimization to maximize the capacity over spatially correlated channels in multiple-input multiple-output (MIMO) wireless systems. The performance of the proposed algorithm is investigated and compared with the existing schemes. Simulation results show that our low complexity algorithm can achieve near-optimal results that converge to within 99% of the optimal results obtained by exhaustive search. In addition, the proposed algorithm achieves near-optimal results irrespective of the mutual relationship between the number of transmit and receive antennas, the statistical properties of the channel and the operating signal-to-noise ratio. 相似文献
103.
This article describes the results of an investigation concerning with the failure of a pipe which was carrying oil from the
control oil unit to the steam turbine control valves servomotor. The failure was in the form of a crack, propagating horizontally
along the pipe. The crack initiated on the outside of the pipe. The cause of the failure was investigated by conducting visual
examination, detailed macro and microstructural examinations and determining the composition of material from the failed pipe.
The composition of the pipe material was analyzed by atomic absorption spectrometer. The failure of the oil pipe was attributed
to stress corrosion cracking. The pipe material is A312 TP 304L. Recommendation to minimize such failures includes coating
the pipe to prevent contact with chloride from the surrounding marine environment. 相似文献
104.
Pashmina, a finest natural animal fiber is utilized for preparation of world famous Kashmiri pashmina shawls by traditional practices. Hand spinning is one of the important processing step, wherein fibers are converted into a fine yarn on a traditional spinning wheel (yander). The task is usually carried out by women folk. It is a laborious process resulting in a lot of physical stress affecting the efficiency of artisans. An innovative charkha has been fabricated to reduce the physical stress and its effect on the spinning efficiency and remuneration of artisans over traditional one was evaluated. The study revealed that innovative charkha was efficient in terms of time consumed for spinning by 73.50% over traditional one besides decreasing physical drudgery. In terms of income, there was an increase of 146% over traditional one for same period of time without deteriorating the quality of yarn. 相似文献
105.
The roles of hybrid-π, two-port, and SPICE transistor parameter are compared. A step-by-step procedure is described for determining numerical parameter values for a dynamic SPICE model of a bipolar junction from transistor manufacturer's measured data. The procedure is illustrated with an example 相似文献
106.
O.P. Malik G.S. Hope M.A.H. Sheirah 《International Journal of Electrical Power & Energy Systems》1983,5(3):159-165
The processing capability of computers makes it feasible to implement sophisticated techniques for process control. However, to minimize the software development costs, it is desirable to develop algorithms that can have a wider application. In keeping with this, an AVR and speed governor for a generating unit have been designed using the same algorithm, called the selftuning regulator. The selftuning AVR and speed governor have been implemented using a microprocessor and a minicomputer online. The feasibility of developing unified algorithms is demonstrated by means of realtime tests, in which the two controllers are used simultaneously for a generating unit physical model. 相似文献
107.
O.P. Malik G.S. Hope Ju M. Gorski V.A. Ushakov 《International Journal of Electrical Power & Energy Systems》1983,5(1):61-71
Results of experimental tests carried out with microprocessor-based voltage and speed regulators using a digital-analogue-physical model complex of a large power system at the Siberian Power Institute of the USSR Academy of Sciences are described. The physical test facility, and the test objectives and procedures are also outlined. Tests were carried out on a Soviet-built microprocessor AVR and a Canadian-built microprocessor AVR and speed governor. The work described shows that the development of speed and voltage regulators using microprocessors is a feasible and promising proposition. 相似文献
108.
Scalable Parallel Algorithms for FPT Problems 总被引:4,自引:0,他引:4
Faisal N. Abu-Khzam Michael A. Langston Pushkar Shanbhag Christopher T. Symons 《Algorithmica》2006,45(3):269-284
Algorithmic methods based on the theory of fixed-parameter tractability are combined with powerful computational platforms
to launch systematic attacks on combinatorial problems of significance. As a case study, optimal solutions to very large instances
of the NP-hard vertex cover problem are computed. To accomplish this, an efficient sequential algorithm and various forms
of parallel algorithms are devised, implemented, and compared. The importance of maintaining a balanced decomposition of the
search space is shown to be critical to achieving scalability. Target problems need only be amenable to reduction and decomposition.
Applications in high throughput computational biology are also discussed. 相似文献
109.
Artificial neural networks can be used as intelligent controllers to control non-linear, dynamic systems through learning, which can easily accommodate the non-linearities and time dependencies. However, they require large training time and large number of neurons to deal with complex problems. Taking benefit of the characteristics of a Generalized Neuron that requires much smaller training data and shorter training time, a Generalized Neuron-Based Power System Stabilizer (GNPSS) and an adaptive version of the same have been developed. The objective of this paper is to compare the performance of the GNPSS with that of an adaptive version, the weights of which are updated on-line. 相似文献
110.
Tamara Sumner Faisal Ahmad Sonal Bhushan Qianyi Gu Francis Molina Stedman Willard Michael Wright Lynne Davis Greg Janée 《International Journal on Digital Libraries》2005,5(1):18-24
Concept browsing interfaces can help educators and learners to locate and use learning resources that are aligned with recognized learning goals. The Strand Map Service enables users to navigate interactive visualizations of related learning goals and to request digital library resources aligned with learning goals. These interfaces are created using a programmatic Web service interface that dynamically generates interactive visual components. Preliminary findings suggest that these library interfaces appear to help users stay focused on the scientific content of their information discovery task, as opposed to focusing on the mechanics of searching. 相似文献