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排序方式: 共有119条查询结果,搜索用时 250 毫秒
51.
52.
This paper studies how to attain fairness in communication for omniscience that models the multi-terminal compress sensing problem and the coded cooperative data exchange problem where a set of users exchange their observations of a discrete multiple random source to attain omniscience—the state that all users recover the entire source. The optimal rate region containing all source coding rate vectors that achieve omniscience with the minimum sum rate is shown to coincide with the core (the solution set) of a coalitional game. Two game-theoretic fairness solutions are studied: the Shapley value and the egalitarian solution. It is shown that the Shapley value assigns each user the source coding rate measured by their remaining information of the multiple source given the common randomness that is shared by all users, while the egalitarian solution simply distributes the rates as evenly as possible in the core. To avoid the exponentially growing complexity of obtaining the Shapley value, a polynomial-time approximation method is proposed which utilizes the fact that the Shapley value is the mean value over all extreme points in the core. In addition, a steepest descent algorithm is proposed that converges in polynomial time on the fractional egalitarian solution in the core, which can be implemented by network coding schemes. Finally, it is shown that the game can be decomposed into subgames so that both the Shapley value and the egalitarian solution can be obtained within each subgame in a distributed manner with reduced complexity. 相似文献
53.
Physical–chemical hybrid transiency: A fully transient li‐ion battery based on insoluble active materials 下载免费PDF全文
Yuanfen Chen Reihaneh Jamshidi Kathryn White Simge Çınar Emma Gallegos Nastaran Hashemi Reza Montazami 《Journal of Polymer Science.Polymer Physics》2016,54(20):2021-2027
Transient Li‐ion batteries based on polymeric constituents are presented, exhibiting a twofold increase in the potential and approximately three orders of magnitude faster transiency rate compared to other transient systems reported in the literature. The battery takes advantage of a close variation of the active materials used in conventional Li‐ion batteries and can achieve and maintain a potential of >2.5 V. All materials are deposited form polymer‐based emulsions and the transiency is achieved through a hybrid approach of redispersion of insoluble, and dissolution of soluble components in approximately 30 min. The presented proof of concept has paramount potentials in military and hardware security applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2021–2027 相似文献
54.
Reza Fazaeli Saiedeh Jamshidi Khatereh A. Pishro 《Journal of organometallic chemistry》2007,692(18):3984-3993
The density functional theory calculations were used to study the influence of the substituent at P on the oxidative addition of PhBr to Pd(PX3)2 and Pd(X2PCH2CH2PX2) where X = Me, H, Cl. It was shown that the Cipso-Br activation energy by Pd(PX3)2 correlates well with the rigidity of the X3P-Pd-PX3 angle and increases via the trend X = Cl < H < Me. The more rigid the X3P-Pd-PX3 angle is, the higher the oxidative addition barrier is. The exothermicity of this reaction also increases via the same sequence X = Cl < H < Me. The trend in the exothermicity is a result of the Pd(II)-PX3 bond strength increasing faster than the Pd(0)-PX3 bond strength upon going from X = Cl to Me. Contrary to the trend in the barrier to the oxidative addition of PhBr to Pd(PX3)2, the Cipso-Br activation energy by Pd(X2PCH2CH2PX2) decreases in the following order X = Cl > H > Me. This trend correlates well with the filled dπ orbital energy of the metal center. For a given X, the oxidative addition reaction energy was found to be more exothermic for the case of X2PCH2CH2PX2 than for the case of PX3. This effect is especially more important for the strong electron donating phosphine ligands (X = Me) than for the weak electron donating phosphine ligands (X = Cl). 相似文献
55.
Raheleh Bakhshi Ebrahim Vasheghani‐Farahani Hamid Mobedi Ahmad Jamshidi Mazyar Khakpour 《先进技术聚合物》2006,17(5):354-359
Biodegradable in situ forming drug delivery systems for naltrexone release are promising for post‐treatment of drug addicts. The effect of two different additives, glycerol and ethyl heptanoate, on the naltrexone hydrochloride release and solvent removal from a poly(DL ‐lactide‐co‐glycolide) (PLGA) injectable implant is presented in this article. The experimental results showed that the in vitro initial release of the drug was decreased in the presence of these additives. Ethyl heptanoate was, however, more effective than glycerol and increasing the amount of additives in PLGA solution up to 5% (w/w) resulted in a decrease of initial naltrexone release rate up to 50%. The morphological evaluation of implants using scanning electron microscopy indicated that the additives generated a less porous structure together with a finger‐like to sponge‐like transition. The solvent removal profiles of injectable implants, which can be well described by thermogravimetric and morphological analysis, were in good agreement with drug release profiles. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
56.
Gurtner C Tu E Jamshidi N Haigis RW Onofrey TJ Edman CF Sosnowski R Wallace B Heller MJ 《Electrophoresis》2002,23(10):1543-1550
A variety of electronic DNA array devices and techniques have been developed that allow electric field enhanced hybridization to be carried out under special low-conductance conditions. These devices include both planar microelectronic DNA array/chip devices as well as electronic microtiter plate-like devices. Such "active" electronic devices are able to provide controlled electric (electrophoretic) fields that serve as a driving force to move and concentrate nucleic acid molecules (DNA/RNA) to selected microlocation test-sites on the device. In addition to ionic strength, pH, temperature and other agents, the electric field provides another controllable parameter that can affect and enhance DNA hybridization. With regard to the planar microelectronic array devices, special low-conductance buffers were developed in order to maintain rapid transport of DNA molecules and to facilitate hybridization within the constrained low current and voltage ranges for this type of device. With regard to electronic microtiter plate type devices (which do not have the low current/voltage constraints), the use of mixed buffers (low conductance upper chamber/high conductance lower chamber) can be used in a unique fashion to create favorable hybridization conditions in a microzone within the test site location. Both types of devices allow DNA molecules to be rapidly and selectively hybridized at the array test sites under conditions where the DNA in the bulk solution can remain substantially denatured. 相似文献
57.
Shahriar Sharifi Hamid Mirzadeh Mohammad Imani Farshid Ziaee Maryam Tajabadi Ahmad Jamshidi Mohammad Atai 《先进技术聚合物》2008,19(12):1828-1838
Photocrosslinkable and biodegradable polymeric networks were formulated based on N‐vinyl pyrrolidone‐poly(ε‐caprolactone fumarate) (NVP/PCLF) compositions for hard tissue engineering applications using a new proton scavenger, propylene oxide (PO). The synthesized macromers were obtained as a white clear paste with no colorization. The obtained macromers were thoroughly characterized using spectroscopic (NMR and FT‐IR) and chromatographic (gel permeation chromatography (GPC)) techniques. Photocrosslinking of the PCLF/NVP compositions was achieved using camphorquinone and dimethyl toluidine (DMT) as a photoinitiator system. The cytocompatibility of the macromers and their corresponding networks were evaluated via MTT assay. Characterization of the networks indicated the importance of NVP content on the network properties. Sol fraction studies indicated that more than 90% of the PCLFs were crosslinked over the studied range of PCLF/NVP compositions; however most of the NVP above a stoichiometric ratio of one NVP to fumerate unit remained unreacted. It was also found that in the concentrations more than 10% NVP, the unreacted NVP monomer neither participated in the crosslinking reaction nor homopolymerized to poly(vinyl pyrrolidone) (PVP). The elastic modulus (G′) and estimated molecular weight between crosslinks also confirmed that at the higher NVP content the PCLF photocrosslinking was hindered. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
58.
Rofouei Mohammad Kazem Jamshidi Sarah Seidi Shahram Saleh Abolfazl 《Mikrochimica acta》2017,184(9):3425-3432
Microchimica Acta - Bucky gels are gelatinous composite materials consisting of carbon nanotubes and ionic liquids. The authors describe the synthesis of a bucky gel containing Fe3O4 nanoparticles... 相似文献
59.
Marjan Jebeli Javan Zahra Aliakbar Tehrani Alireza Fattahi Zahra Jamshidi 《Structural chemistry》2012,23(6):1843-1855
The relative stabilities and noncovalent interactions of the six low-lying energy tautomers of cytosine nucleobase with some biological anions (such as F?, Cl?, and CN?) have been investigated in gas phase by density functional theory (DFT) method in conjunction with 6-311++G (d,p) atomic basis set. Furthermore, to systematically investigate all possible tautomerisms from cytosine induced by proton transfer, we describe a study of structural tautomer interconversion in the gas phase and in a continuum solvent using DFT calculation. We carried out geometrical optimizations with the integral equation formalism of polarizable continuum (IEF-PCM) model to account for the solvent effect, and the results were compared with those in the gas phase. The result of calculation revealed that anions bind mostly in a bidentate manner via hydrogen bond, and stabilization energies of these complexes are larger than those in the case when anions bind in a monodentate manner. The quantum theory of atoms in molecules (QTAIM), natural bonding orbital (NBO) and energy decomposition analysis (EDA) have also been applied to understand the nature of hydrogen bond interactions in these complexes. NBO analysis reveals that the interaction patterns between the anions and the tautomers are ??-type interaction between lone pairs and $ \sigma_{{_{{{\text{N}}--{\text{H}}}} }}^{*} $ , $ \sigma_{{_{{{\text{O}}--{\text{H}}}} }}^{*} $ and $ \sigma_{{_{{{\text{H}}--{\text{F}}}} }}^{*} $ antibonding orbitals. Also, according to these theories, the interactions are found to be partially electrostatic and partially covalent. EDA results identify that these bonds have less than 35% covalent character and more than 65% electrostatic, and the covalent character increases in different anions in the order F??>?CN??>?Cl?. On the other hand, orbital interaction energies of complexes of F? anion are more than those of Cl? and CN? complexes. The lower orbital interaction energies in complexes of Cl? and CN?anions imply less charge transfer and stronger ionic bond character. Furthermore, relationship between the orbital interaction energy (E 2) with hydrogen bonding energy (E H···X) and the electron density (??(r)) with hydrogen bonding energy of F?, Cl? and CN? complexes have also been investigated. 相似文献
60.
Vibration analysis of cracked post-buckled beam is investigated in this study. Crack, assumed to be open, is modeled by a massless rotational spring. The beam is divided into two segments and the governing nonlinear equations of motion for the post-buckled state are derived. The solution consists of static and dynamic parts, both leading to nonlinear differential equations. The differential quadrature has been used to solve the problem. First, it is applied to the equilibrium equations, leading to a nonlinear algebraic system of equations that will be solved utilizing an arc length strategy. Next, the differential quadrature is applied to the linearized dynamic differential equations of motion and their corresponding boundary and continuity conditions. Upon solution of the resulting eigenvalue problem, the natural frequencies and mode shapes of the cracked beam are extracted. Several experimental as well as numerical case studies are performed to demonstrate the effectiveness of the proposed method. The investigation also includes an examination of several parameters influencing the dynamic behavior of the problem. The results show that the position and size of the crack as well as the geometric imperfection and applied load largely affect the modal shapes and natural frequencies of the beam. 相似文献