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81.
The objective of this research is to develop a new method of grinding process that can efficiently make concave profile of the worm thread smooth. The grinding is carried out using a wheel with curvature profile in the axial plane in the form of an arc of logarithmic spiral. The proposed method will provide maximum line of contact between the tool and the worm with minimum stress concentration at any point. The generating equation of the grinding tool profile and its arrangement with respect to the worm during thread grinding were determined. 相似文献
82.
The time discretization in the Discontinuous Galerkin (DG) scheme has been traditionally based on the Total Variation Diminishing (TVD) second-order Runge-Kutta (RK2) scheme. Computational efficiency and accuracy with the Euler Forward (EF) and the TVD second-order RK2 time stepping schemes in the DG method are investigated in this work. Numerical tests are conducted with the scalar Burgers equation, 1-D and 2-D shallow water flow equations. The maximum Courant number or time step size required for stability for the EF scheme and RK2 scheme with different slope limiters are compared. Numerical results show that the slope limiters affect the stability requirement in the DG method. The RK2 scheme is generally more diffusive than the EF scheme, and the RK2 scheme allows larger time step sizes. The EF scheme is found to be more efficient and accurate than the RK2 scheme in the DG method in computation. 相似文献
83.
Abdullah AH Abdullah EA Zainal Z Hussein MZ Ban TK 《Water science and technology》2012,65(9):1632-1638
The adsorption of methyl orange dye from aqueous solution onto penta-bismuth hepta-oxide nitrate, Bi(5)O(7)NO(3), synthesized by precipitation method, was studied in a batch adsorption system. The effects of operation parameters such as adsorbent dose, initial dye concentration, pH and temperature were investigated. The adsorption equilibrium and mechanism of adsorption was evaluated by Langmuir and Freundlich isotherm and different kinetic models, respectively. The results indicate that adsorption is highly dependent on all operation parameters. At optimum conditions, the adsorption capacity was found to be 18.9 mg/g. The adsorption data fits well with the Langmuir isotherm model indicating monolayer coverage of adsorbate molecules on the surface of Bi(5)O(7)NO(3). The kinetic studies show that the adsorption process is a second-order kinetic reaction. Although intra-particle diffusion limits the rate of adsorption, the multi-linearity plot of intra-particle model shows the importance of both film and intra-particle diffusion as the rate-limiting steps of the dye removal. Thermodynamic parameters show that the adsorption process is endothermic, spontaneous and favourable at high temperature. 相似文献
84.
In recent years, a few sequential covering algorithms for classification rule discovery based on the ant colony optimization
meta-heuristic (ACO) have been proposed. This paper proposes a new ACO-based classification algorithm called AntMiner-C. Its
main feature is a heuristic function based on the correlation among the attributes. Other highlights include the manner in
which class labels are assigned to the rules prior to their discovery, a strategy for dynamically stopping the addition of
terms in a rule’s antecedent part, and a strategy for pruning redundant rules from the rule set. We study the performance
of our proposed approach for twelve commonly used data sets and compare it with the original AntMiner algorithm, decision
tree builder C4.5, Ripper, logistic regression technique, and a SVM. Experimental results show that the accuracy rate obtained
by AntMiner-C is better than that of the compared algorithms. However, the average number of rules and average terms per rule
are higher. 相似文献
85.
Md Tasyrif Abdul Rahman Nobuyuki KawaharaKazuya Tsuboi Eiji Tomita 《International Journal of Hydrogen Energy》2014
In this work, spark-induced breakdown spectroscopy (SIBS) was employed to investigate the mixing process of a hydrogen jet in a constant-volume vessel. The local fuel concentration of the hydrogen jet was measured at several locations, using a SIBS sensor. A high-speed camera was used to visualize spark discharge fluctuations, and hydrogen jet concentration measurements were conducted simultaneously. Spectrally resolved atomic emissions from the plasma generated by the spark plug were examined to determine the local equivalence ratio. Direct visualization of the spark discharge provided useful information about the influence of spark discharge characteristics related to the spark timing. Using the developed SIBS sensor, atomic emission spectra were obtained from hydrogen Hα at 656 nm and nitrogen N (I) at 501 nm. Comparison of the intensity peaks of atomic emissions from hydrogen and nitrogen allows the local hydrogen concentration in a measured volume to be determined, and hence also the local equivalence ratio. The measurement results demonstrate the local variation in the equivalence ratio throughout the jet and along its axis. From the results, the spatial structure of the hydrogen jet affects the hydrogen/nitrogen mixing and could be clarified with SIBS technique when the spark is discharged. 相似文献
86.
First and second law investigations of a new solar‐assisted thermodynamic cycle for triple effect refrigeration 下载免费PDF全文
This investigation is persuaded for the first and second law analyses of a new solar‐driven triple‐effect refrigeration cycle using Duratherm 600 oil (Duratherm Extended Life Fluid, NY, USA) as the heat transfer fluid is performed. The proposed cycle is an integration of ejector, absorption, and cascaded refrigeration cycles that could produce refrigeration output of different magnitude at different temperature simultaneously. Both exergy destruction and losses in each component and hence in the overall system are determined to identify the causes and locations of the thermodynamic imperfection. The effects of some influenced parameters such as hot oil outlet temperature, refrigerant turbine inlet pressure, and the evaporator temperature of ejector and cascaded refrigeration cycle have been observed on the first and second law performances. It is found that maximum irreversibility occurs in central receiver as 52.5% and the second largest irreversibility of 25% occurs in heliostat field. The second law efficiency of the solar driven triple effect refrigeration cycle is 2%, which is much lower than its first law efficiency of 11.5%. Analysis clearly shows that performance evaluation based on the first law analysis is inadequate and hence, more meaningful evaluation must be included in the second law analysis. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
87.
Rahaman Md. Saifur Hasnine Shah Md. Marzuk Ahmed Tanvir Sultana Salma Bhuiyan Md. Abdul Quaiyum Manir Md. Serajum Ullah Nayeb Sen Sapan Kumar Hossain Md. Nazmul Hossain Md. Sahadat Dafader Nirmal Chandra 《Iranian Polymer Journal》2021,30(10):1101-1116
Iranian Polymer Journal - Hydrogels were produced from mixtures of polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and acrylic acid (AAc) using γ-radiation at doses of 3, 7, and... 相似文献
88.
Anupam Glorious Lobo Abdul Mujeeb Mahammad Nawaz Adeeb Aman A. P. Abdul Basith 《Polymer-Plastics Technology and Engineering》2016,55(16):1713-1719
Elucidation of the structure of naturally existing or synthesized substances is an important criterion in the study of materials to predict the application of the substance. In this study, polylactide was doped with nano-aluminium oxide and nano-cupric oxide with 1 and 3 mg of concentration variants. The interaction between the polymer matrix and the nanoparticles has been studied using Fourier transform infrared. Successful doping of the polymer has been observed. Attention has been drawn to check the intermolecular bonding in films having varying thicknesses, films prepared at higher sonication temperatures, and chemical homogeneity of the doped polymer films. 相似文献
89.
Pir Abdul Rasool Qureshi Nasrullah Memon 《Journal of Computer and System Sciences》2012,78(4):1248-1257
We present a hybrid model for content extraction from HTML documents. The model operates on Document Object Model (DOM) tree of the corresponding HTML document. It evaluates each tree node and associated statistical features like link density and text distribution across the node to predict significance of the node towards overall content provided by the document. Once significance of the nodes is determined, the formatting characteristics like fonts, styles and the position of the nodes are evaluated to identify the nodes with similar formatting as compared to the significant nodes. The proposed hybrid model is derived from two different models, i.e., one is based on statistical features and other on formatting characteristics and achieved the best accuracy. We describe the validity of model with the help of experiments conducted on the standard data sets. The results revealed that the proposed model outperformed other existing content extraction models. We present a browser based implementation of the proposed model as proof of concept and compare the implementation strategy with various state of art implementations. We also discuss various applications of the proposed model with special emphasis on open source intelligence. 相似文献
90.