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111.
CSI-Based Resource Allocation for OFDM Downlink Broadband Multimedia Services in Cellular Systems 总被引:1,自引:1,他引:0
Using channel state information (CSI) in resource allocation in Orthogonal Frequency Division Multiplexing (OFDM) wireless
cellular systems has been recently considered to improve the overall throughput. This paper presents an analytical framework
to compare the performance of two resource allocation schemes, using CSI-based and random sub-carrier selection, in terms
of their user outage probability and throughput in relation to the system load in frequency-selective fading and interference-limited
environments. Analytical and simulation results are in good agreement and indicate that a proper use of CSI can achieve substantially
better performance in interference limited cellular systems as compared to the blind approach and thus show the benefits of
multi-user diversity. 相似文献
112.
Mohammad Navid Soltani Rad Somayeh Behrouz Mohammad Mahdi Doroodmand Abdollah Movahediyan 《Tetrahedron》2012,68(38):7812-7821
The synthesis and characterization of copper-doped silica cuprous sulfate (CDSCS) as a new and efficient heterogeneous nano catalyst are described. CDSCS has been fully characterized by different microscopic, spectroscopic and physical techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic forced microscopy (AFM), X-ray diffraction (XRD), inductively coupled plasma (ICP) analysis, thermogravimetric analysis (TGA) and FT-IR. CDSCS is proved to be a useful heterogeneous nano catalyst in Cu(I)-catalyzed ‘Click’ cycloaddition of organic azides with terminal alkynes. CDSCS catalyzes the 1,3-dipolar cycloaddition reactions of β-azido alcohols and alkynes at room temperature, in THF/H2O (1:1, v/v) solution. Using CDSCS, 1,4-disubstituted 1,2,3-triazole adducts are mainly obtained, in good to excellent yields and in short reaction times. These compounds have featural resemblance to β-adrenoceptor blocking agents. CDSCS was approved as a chemically and thermally stable nano catalyst that can be reused for many consecutive trials without a significant decline in its reactivity. 相似文献
113.
Navid Noroozi Mehdi Roopaei M. Zolghadri Jahromi 《Communications in Nonlinear Science & Numerical Simulation》2009,14(11):3978-3992
Most physical systems inherently contain nonlinearities which are commonly unknown to the system designer. Therefore, in modeling and analysis of such dynamic systems, one needs to handle unknown nonlinearities and/or uncertain parameters. This paper proposes a new adaptive tracking fuzzy sliding mode controller for a class of nonlinear systems in the presence of uncertainties and external disturbances. The main contribution of the proposed method is that the structure of the controlled system is partially unknown and does not require the bounds of uncertainty and disturbance of the system to be known; meanwhile, the chattering phenomenon that frequently appears in the conventional variable structure systems is also eliminated without deteriorating the system robustness. The performance of the proposed approach is evaluated for two well-known benchmark problems. The simulation results illustrate the effectiveness of our proposed controller. 相似文献
114.
Navid Dehnavi Kazem Parivar Vahabodin Goodarzi Ali Salimi Mohammad Reza Nourani 《先进技术聚合物》2019,30(9):2192-2206
Peripheral nerve injury can considerably affect the daily life of affected people through reduced function and permanent deformation of the nerve. One of the conventional treatments used for the management of the disease is the application of autograft, which is recognized as a golden standard method; however, the process of gaining access to autograft has posed a significant challenge to its use. Nerve guidance channels (conduits), which are made in different methods, can act as an alternative therapy for patients that have undergone nerve injury; but, achieving these conduits has always been a major dilemma to be applied for patients with nerve injury. In this study, a novel conduit based on polymer blend nanocomposites of polyglycolic acid (PGA), collagen, and nanobioglass (NBG) were prepared by electrospinning technique and then compared with PGA/collagen and PGA conduits that were made in previous studies. Additionally, their various properties were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), contact angle, dynamic mechanical thermal analysis (DMTA), tensile strength, Fourier‐transform infrared (FTIR), and the porosity and degradation. The results showed that the mechanical, chemical, biocompatibility, and biodegradability properties of PGA/collagen/NBG conduits were more favorable in comparison with other materials. According to 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and 4′,6‐diamidino‐2‐phenylindole (DAPI) staining technique, nanofibrous electrospun PGA/collagen/NBG conduits are more suitable for cell adhesion and proliferation in comparison with either PGA or PGA/collagen conduits and can have potential for nerve regeneration. 相似文献
115.
M. Karimi M. Rabiee F. Moztarzadeh M. Bodaghi M. Tahriri 《Solid State Communications》2009,149(41-42):1765-1768
The preparation of thin films of CdS by chemical bath deposition is mostly based on the utilisation of ammonia as a complexing agent for cadmium ions. Here we report on a technique based on sodium citrate dihydrate that eliminates the problems of ammonia volatility and toxicity. The crystallites with a size range of 10–20 nm in diameter with zinc blend (cubic) and wurtzite (hexagonal) crystal structures and strong photoluminescence were prepared from the mixture solutions of: cadmium chloride dihydrate as a cadmium source, thiourea as a sulfur source and sodium citrate dihydrate as a complexing agent for cadmium ions. The well-cleaned glass used as a substrate for thin film deposition. The obtained samples were characterized by the techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscope (AFM) and fluorescence spectroscopy. Also, the effect of two operating conditions, (i) pH, and (ii) the temperature of reaction on the synthesizing of CdS nanocrystals was examined. Finally, it was found that the CdS nanocrystals showed sharp excitation features and strong ”band-edge” emission. 相似文献
116.
Soheilnia N Kleinke KM Dashjav E Cuthbert HL Greedan JE Kleinke H 《Inorganic chemistry》2004,43(20):6473-6478
A new modification of CuTi(2)S(4) was prepared from the elements at 425 degrees C. It crystallizes in the rhombohedral space group Rm, with lattice parameters of a = 7.0242(4) A, c = 34.834(4) A, and V = 1488.4(2) A(3) (Z = 12). Two topologically different interlayer regions exist between the close-packed S layers that alternate along the c axis: one comprises both Cu (in tetrahedral voids) and Ti atoms (in octahedral voids), and the second exclusively Ti atoms (again in octahedral voids). In contrast to the known modification, the spinel, Cu-Ti interactions of 2.88 A occur that have bonding character according to the electronic structure calculations. Both CuTi(2)S(4) modifications are metallic Pauli paramagnets due to Ti d contributions. The Pauli susceptibility of the Rm form is larger than that of the thiospinel in quantitative agreement with the LMTO-ASA band structure calculations. The irreversible transformation to the spinel takes place at temperatures above 450 degrees C. 相似文献
117.
Haji Shabani AM Dadfarnia S Nasirizadeh N 《Analytical and bioanalytical chemistry》2004,378(5):1388-1391
Trace amounts of inorganic mercury (Hg2+) and methylmercury cations (MeHg2+) were adsorbed quantitatively from acidic aqueous solution onto a column packed with immobilized dithizone on microcrystalline naphthalene. The trapped mercury was eluted with 10 ml of 7 mol L–1 hydrochloric acid solution. The Hg2+ was then directly reduced with tin (II) chloride, and volatilized mercury was determined by cold vapor atomic absorption spectrometry (CVAAS). Total mercury (Hgt) was determined after decomposition of MeHg+ into Hg2+. Hg2+ and MeHg+ cations were completely recovered from the water with a preconcentration factor of 200. The relative standard deviation obtained for eight replicate determinations at a concentration of 0.3 g L–1 was 1.8%. The procedure was applied to analysis of water samples, and the accuracy was assessed via recovery experiment. 相似文献
118.
Krämer S Xie H Gaff J Williamson JR Tkachenko AG Nouri N Feldheim DA Feldheim DL 《Journal of the American Chemical Society》2004,126(17):5388-5395
This paper describes a simple method for the preparation and characterization of protein density gradients on solid supports. The method employs colloidal metal nanoparticles as protein carriers and optical tags and is capable of forming linear, exponential, 1D, 2D, and multiprotein gradients of varying slope without expensive or sophisticated surface patterning techniques. Surfaces patterned with proteins using the procedures described within are shown to support cell growth and are thus suitable for studies of protein-cell interactions. 相似文献
119.
Abouzar Roeintan Sayed Mojtba Moosavi Mohammad Navid Soltani Rad Somayeh Behrouz 《中国化学会会志》2015,62(12):1097-1104
The ‘click synthesis’ of some novel O‐substituted oximes, 5a – 5j , which contain heterocycle residues, as new analogs of ß‐adrenoceptor antagonists is described (Scheme 1). The synthesis of these compounds was achieved in four steps. The formation of (E)‐2‐(1H‐benzo[d]imidazol‐1‐yl)‐1‐phenylethanone oxime, followed by their reaction with 2‐(chloromethyl)oxirane, afforded mixture of oil compounds 3 and 4 , which by a subsequent tetra‐n‐butylammonium bromide (TBAB)‐catalyzed reaction with N H heterocycle compounds (Scheme 1), led to the target compounds 5a – 5j in good yields. 相似文献
120.
Rajagopal Karthikeyan Hasanzadeh Navid Parastesh Fatemeh Hamarash Ibrahim Ismael Jafari Sajad Hussain Iqtadar 《Nonlinear dynamics》2020,101(1):711-718
Nonlinear Dynamics - The outbreak of the novel coronavirus (COVID-19), which was firstly reported in China, has affected many countries worldwide. To understand and predict the transmission... 相似文献