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排序方式: 共有2054条查询结果,搜索用时 11 毫秒
91.
The Jameson flotation cell has been commonly used to treat a variety of ores (lead, zinc, copper etc.), coal and industrial minerals at commercial scale since 1989. It is especially known to be highly efficient at fine and ultrafine coal recovery. However, although the Jameson cell has quite a simple structure, it may be largely inefficient if the design and operating parameters chosen are not appropriate. In this study, the design and operating parameters of a pilot scale Jameson cell were optimized to obtain a desired metallurgical performance in the slime coal flotation. The optimized design parameters are the nozzle type, the height of the nozzle above the pulp level, the downcomer diameter and the immersion depth of the downcomer. Among the operating parameters optimized are the collector dosage, the frother dosage, the percentage of solids and the froth height. In the optimum conditions, a clean coal with an ash content of 14.90% was obtained from the sample slime having 45.30% ash with a combustible recovery of 74.20%. In addition, a new type nozzle was developed for the Jameson cell, which led to an increase of about 9% in the combustible recovery value. 相似文献
92.
93.
Fire detection in video sequences using a generic color model 总被引:3,自引:0,他引:3
In this paper, a rule-based generic color model for flame pixel classification is proposed. The proposed algorithm uses YCbCr color space to separate the luminance from the chrominance more effectively than color spaces such as RGB or rgb. The performance of the proposed algorithm is tested on two sets of images, one of which contains fire, the other containing fire-like regions. The proposed method achieves up to 99% fire detection rate. The results are compared with two other methods in the literature and the proposed method is shown to have both a higher detection rate and a lower false alarm rate. Furthermore the proposed color model can be used for real-time fire detection in color video sequences, and we also present results for segmentation of fire in video using only the color model proposed in this paper. 相似文献
94.
M. Schulz R. Moshammer M. Dürr A. Hasan M.F. Ciappina 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(2):187-191
Recent developments on kinematically complete experiments on basic atomic fragmentation processes are reviewed. Comparisons between theoretical and experimental fully differential cross sections for single ionization of light atoms by charged particle impact are analyzed. Furthermore, a method developed very recently, four-particle Dalitz plots, is discussed in context of double ionization. The extraordinary power of these plots is their capability to provide a comprehensive picture of the momentum exchange between all four final-state particles in a single spectrum. 相似文献
95.
Sobia Noreen Sara Hasan Shazia Akram Ghumman Syed Nasir Abbas Bukhari Bushra Ijaz Huma Hameed Huma Iqbal Afeefa Aslam Mervat Abdelaziz Mohamed Elsherif Shazia Noureen Hasan Ejaz 《International journal of molecular sciences》2022,23(5)
The rapid progression in biomaterial nanotechnology apprehends the potential of non-toxic and potent polysaccharide delivery modules to overcome oral chemotherapeutic challenges. The present study is aimed to design, fabricate and characterize polysaccharide nanoparticles for methotrexate (MTX) delivery. The nanoparticles (NPs) were prepared by Abelmoschus esculentus mucilage (AEM) and chitosan (CS) by the modified coacervation method, followed by ultra-sonification. The NPs showed much better pharmaceutical properties with a spherical shape and smooth surface of 213.4–254.2 nm with PDI ranging between 0.279–0.485 size with entrapment efficiency varying from 42.08 ± 1.2 to 72.23 ± 2.0. The results revealed NPs to possess positive zeta potential and a low polydispersity index (PDI). The in-vitro drug release showed a sustained release of the drug up to 32 h with pH-dependence. Blank AEM -CS NPs showed no in-vivo toxicity for a time duration of 14 days, accompanied by high cytotoxic effects of optimized MTX loaded NPs against MCF-7 and MD-MBA231 cells by MTT assay. In conclusion, the findings advocated the therapeutic potential of AEM/CS NPs as an efficacious tool, offering a new perspective for pH-responsive routing of anticancer drugs with tumor cells as a target. 相似文献
96.
Mahdi N. Mahyari Hasan Karimi Hasan Naseh Mehran Mirshams 《Journal of Mechanical Science and Technology》2010,24(10):1997-2006
The focus of the present study is to investigate the effectiveness of installing vortex breakers at the outlet of launch vehicle
tanks on postponing vortex formation and decreasing the critical height of propellants while discharging. Analytical results
in the absence of a vortex breaker show that the effects of the Weber and Reynolds numbers in the flow field can be ignored
for values greater than 720 and 1.1 × 105, respectively; and critical height can be considered as a function of Froude number under aforementioned conditions. The
analytical criteria are verified by two-dimensional, axis symmetrical, transient and two-phase numerical model. Eventually,
some experiments are conducted to examine the effectiveness of the applied vortex breakers in reduction of the critical height
of propellant. Experimental results show that a 30% decrease can be achieved in critical height by using a particular type
of vortex breaker. Additionally, the carried out simulations for an existing two-stage launch vehicle indicate a 13% increase
in orbital altitude, which in turn proves the considerable improvement in launch vehicle mass/energetic capabilities. 相似文献
97.
Canjie Wu Li Han Hasan Riaz Shujuan Wang Kailai Cai Liguo Yang 《Food chemistry》2013,136(3-4):1122-1129
β-Cryptoxanthin, a provitaminic carotenoid, present in many fruits and vegetables, has been associated with decreased risk of chronic diseases, including cancer. The influence of β-cryptoxanthin derived from mandarin on the proliferation of the stomach tumor cell line BGC-823 was tested using MTT and cell count assay at 72 h and dose–response (from 0.01 to 20 μM). β-Cryptoxanthin suppressed the cell migration by the scratch assay. Furthermore, β-cryptoxanthin induced an accumulation of cells in the G1/G0 phase of the cell cycle (as detected by flow cytometry), which was in accordance with an increased expression of p21 and down regulations of cyclin D1 and cyclin E, detected by Western blot analysis, and β-cryptoxanthin increased the mRNA levels of retinoic acid receptor β (RARβ) with the treatment at 10 μM for 24 h. Collectively, the above findings suggest that β-cryptoxanthin could be therapeutic in the treatment of stomach cancer cell in vitro. 相似文献
98.
SPARCL: an effective and efficient algorithm for mining arbitrary shape-based clusters 总被引:3,自引:3,他引:0
Vineet Chaoji Mohammad Al Hasan Saeed Salem Mohammed J. Zaki 《Knowledge and Information Systems》2009,21(2):201-229
Clustering is one of the fundamental data mining tasks. Many different clustering paradigms have been developed over the years,
which include partitional, hierarchical, mixture model based, density-based, spectral, subspace, and so on. The focus of this
paper is on full-dimensional, arbitrary shaped clusters. Existing methods for this problem suffer either in terms of the memory
or time complexity (quadratic or even cubic). This shortcoming has restricted these algorithms to datasets of moderate sizes.
In this paper we propose SPARCL, a simple and scalable algorithm for finding clusters with arbitrary shapes and sizes, and
it has linear space and time complexity. SPARCL consists of two stages—the first stage runs a carefully initialized version
of the Kmeans algorithm to generate many small seed clusters. The second stage iteratively merges the generated clusters to
obtain the final shape-based clusters. Experiments were conducted on a variety of datasets to highlight the effectiveness,
efficiency, and scalability of our approach. On the large datasets SPARCL is an order of magnitude faster than the best existing
approaches. 相似文献
99.
Ahmad Feyz Dizaji Hossein Ali Sepiani Farzad Ebrahimi Akbar Allahverdizadeh Hasan Ali Sepiani 《Journal of Mechanical Science and Technology》2009,23(8):2299-2307
An initial-boundary value problem that is Duffing’s oscillator with time varying coefficients will be studied. Using Banach’s
fixed-point theorem, the existence of periodic solution of the equation will be predicted. The method applied in this paper
is the Schauder second fixed point theorem, which includes the response of structures under vibratory force systems. As an
example, the dynamics of nonlinear simply supported rectangular thin plate under influence of a relatively moving mass is
studied. By expansion of the solution as a series of mode functions, the governing equations of motion are reduced to an ordinary
differential equation for time development vibration amplitude, which is Duffing’s oscillator. Finally, a parametric study
is developed, after that some numerical examples are solved, and the validity of the present analysis is clearly shown.
This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho
Hossein Ali Sepiani received his B.S. degree in Mechanical Engineering from University of Kashan, Iran, in 2003. He then received his M.S. degree
from University of Tehran, in 2006. Currently, Hossein is continuing his research at University of Tehran. His research interests
include new materials (FGMs, Nano-materials, SMAs, SMPs, etc), Composites (Woven Fabrics and Fiber Metal Laminates), Smart
Materials (Shape Memory Alloy, Magnet/Electro-rheological and Piezoelectric Sensors and Actuators), Intelligent structures
(Structures integrated with smart materials), Vibration and control of Intelligent Structures and their application.
Ahmad Feyz Dizaji got his B.S. degree from University of Tehran, Iran, in 1970. Then he continued his study in U.S. and received his PhD. degree
from Michigan State University in 1983, in Applied Mathematics under the supervision of Professor Shui-ni Chow and Professor
J. Mallet-Paret. Since then he has been a member of the Faculty of Engineering in University of Tehran, teaching mathematics
in both undergraduate and graduate levels. 相似文献
100.
Hasan Yalcin Ismet ?zt��rk Eray Tuluk?u Osman Sa?dic 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2011,6(2):197-202
Sar? 85 (Linum usitatissimum L.) linseed variety was used in this study. Linseed was cultivated at 2008 (LS-08) and 2009 (LS-09) without fertilizer. In addition, at 2009 diammonium phosphate [(NH4)2HPO4] and ammonium nitrate (NH4NO3) were applied (LSF-09). The linseeds were analyzed for protein, ash and oil contents and fatty acid compositions. There were differences among harvesting years for oil, protein and ash contents of the seeds. The greater oil and protein contents were obtained during LS-08 compared with LS-09. There were no significant difference in protein and ash content between LS-09 and LSF-09 while a significant difference was observed in oil content. Seed protein, oil and ash contents were significantly affected by the harvesting year, but only oil content was affected by the fertilizer treatment. There are significant differences in palmitic, stearic, oleic, ??-linolenic and arachidic acid between LS-08 and LS-09. While palmitic, stearic, oleic acid decreased, ??-linolenic and arachidic acid increased during 2009 harvesting year. LSF-09 has the highest amount of ??-linolenic acid. The fertilizing treatment seems to have an increasing effect on the amount of ??-linolenic acid, while it has a decreasing effect on the oleic acid content. 相似文献