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41.
42.
The Maxwell-Stefan (MS) formulation, as applied to zeolites that contain both weak and strong adsorption sites, such as ZSM-5, is compared to dynamic Monte Carlo simulations, for the limiting case of single-component self-diffusion. This study is intended as a consistency check, and as a step towards an analytical or semi-analytical theory for self-diffusion in zeolites with multiple types of sites. In its original form, when it is assumed that ζ, the ratio of the self-exchange coefficient to the corrected diffusivity, is equal to 1, the MS formulation performs well for silicalite, the all-Si version of ZSM-5. However, when there are lattice heterogeneities or the topology of the pore network differs from that of silicalite, it is necessary to assume [Formula: see text]. Because ζ is generally occupancy dependent, the theory is unsuited as a fully predictive theory for self-diffusion in heterogeneous microporous solids, unless a theory for ζ is derived. However, since several studies have demonstrated that the MS formulation is able to predict multi-component diffusivities from single-component diffusivities for zeolites with one type of site, an extension to zeolites with multiple types of sites would be very valuable. 相似文献
43.
Information system design forms the most vital element in designing an organization. An information system for a city planning agency is a combination of people, computer hardware and software, a dynamic data base and a set of generalized interactive algorithms.City planning agencies require complete and current information in order to provide input into municipal government decision process. This paper presents a model for an information system based on the operational functions of various city departments. The emphasis of this paper is on system engineering considerations and there is no attempt to provide a detailed programming solution. Basic considerations include: operational requirements, planning requirements, political environment and level of computer expertise. The basic components of the model are an on-line interactive system with a data-base shared by the participating departments. 相似文献
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45.
We address the problem of counting emitted photons in two-photon laser scanning microscopy. Following a laser pulse, photons are emitted after exponentially distributed waiting times. Modeling the counting process is of interest because photon detectors have a dead period after a photon is detected that leads to an underestimate of the count of emitted photons. We describe a model which has a Poisson \((\alpha )\) number N of photons emitted, and a dead period \(\Delta \) that is standardized by the fluorescence time constant \(\tau (\delta = \Delta /\tau )\), and an observed count D. The estimate of \(\alpha \) determines the intensity of a single pixel in an image. We first derive the distribution of D and study its properties. We then use it to estimate \(\alpha \) and \(\delta \) simultaneously by maximum likelihood. We show that our results improve the signal-to-noise ratio, hence the quality of actual images. 相似文献
46.
A concurrent control architecture for autonomous mobile robots using Asynchronous Production Systems
S.S. Iyengar Jeffrey Graham V.G. Hegde Phill Graham F.G. Pin 《Automation in Construction》1993,1(4):371-401
The quest for efficient real-time response by autonomous robots in hazardous environments necessitates not only fast computational schemes in expert systems but also requires insights on high performance data structures and concurrent algorithms that lead to elegant problem-solving methods in the AI discipline. towards this objective, this paper presents an Asynchronous Production System (APS) of architecture capable of monitoring and processing real-time information. 相似文献
47.
Komathi Shanmugasundaram Palaniappan Subramanian Manisankar Paramasivam Gopalan Anantha Iyengar Kwang-Pill Lee 《Gold bulletin》2011,44(1):37-42
Functional nanofibrous polymer membranes were prepared by incorporating poly(2-aminothio phenol) (P2AT) stabilized Au NPs onto electrospun polyvinylidene fluoride (PVdF) nanofibers (designated as P2AT-Au NPs@PVdF-NFM). The preparation of P2AT-Au NPs@PVdF-NFM involves two steps: loading of 2AT (monomer) into electrospun PVdF nanofibrous membrane and polymerization of 2AT by gold chloride. P2AT and Au NPs were simultaneously formed into the electrospun PVdF-NFM. Transmission electron microscope image of P2AT-Au NPs@PVdF-NFM informs the presence of Au NPs (with sizes ~10 nm) onto PVdF-NFM. 相似文献
48.
Yu‐Ping Zhang Se‐Hee Lee Kakarla Raghava Reddy Anantha Iyengar Gopalan Kwang‐Pill Lee 《应用聚合物科学杂志》2007,104(4):2743-2750
SiO2/Poly(3‐aminophenylboronic acid) (PAPBA) composites were synthesized under different experimental conditions, using ultrasonic irradiation method. Polymerization was carried out in the presence of sodium fluoride and D ‐fructose to anchor 3‐aminophenylboronic acid groups on to SiO2 surface. The SiO2/PAPBA nanocomposite prepared by NaF and D ‐fructose in the polymerization medium was found to show different morphology, electrical properties, thermal behavior and structural characterization in comparison to the nanocomposites prepared under other conditions. Ultrasonic irradiation minimizes the aggregation of nanosilica and promotes anchoring of PAPBA units over SiO2 surface. The morphology of PAPBA/ SiO2 nanocomposite was investigated by using transmission electron microscopy, UV‐visible spectroscopy; thermogravimetric analysis, Fourier transform infrared spectroscopy, and X‐ray diffraction analysis were used for characterization. Transmission electron microscope of the nanocomposites observation shows that SiO2/PAPBA composite, prepared with D ‐fructose and NaF under ultrasonication has a core–shell morphology. The thermal and crystalline properties of core‐shell SiO2/PAPBA nanocomposite was prepared via ultrasonication method is different from the SiO2/PAPBA nanocomposite prepared via conventional stirring method, in which SiO2 nanoparticles are submerged in PAPBA. Conductivity of the composite prepared via ultrasonication shows around 0.2 S/cm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2743–2750, 2007 相似文献
49.
Nanocomposites of iron oxide (Fe3O4) with a sulfonated polyaniline, poly(aniline‐co‐aminonaphthalenesulfonic acid) [SPAN(ANSA)], were synthesized through chemical oxidative copolymerization of aniline and 5‐amino‐2‐naphthalenesulfonic acid/1‐amino‐5‐naphthalenesulfonic acid in the presence of Fe3O4 nanoparticles. The nanocomposites [Fe3O4/SPAN(ANSA)‐NCs] were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, elemental analysis, UV–visible spectroscopy, thermogravimetric analysis (TGA), superconductor quantum interference device (SQUID), and electrical conductivity measurements. The TEM images reveal that nanocrystalline Fe3O4 particles were homogeneously incorporated within the polymer matrix with the sizes in the range of 10–15 nm. XRD pattern reveals that pure Fe3O4 particles are having spinel structure, and nanocomposites are more crystalline in comparison to pristine polymers. Differential thermogravimetric (DTG) curves obtained through TGA informs that polymer chains in the composites have better thermal stability than that of the pristine copolymers. FTIR spectra provide information on the structure of the composites. The conductivity of the nanocomposites (~ 0.5 S cm?1) is higher than that of pristine PANI (~ 10?3 S cm?1). The charge transport behavior of the composites is explained through temperature difference of conductivity. The temperature dependence of conductivity fits with the quasi‐1D variable range hopping (quasi‐1D VRH) model. SQUID analysis reveals that the composites show ferromagnetic behavior at room temperature. The maximum saturation magnetization of the composite is 9.7 emu g?1. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
50.
Kwang‐Pill Lee Anantha Iyengar Gopalan See‐Hee Lee Ali Md Showkat Young Chang Nho 《应用聚合物科学杂志》2006,102(4):3912-3918
Conducting polydiphenylamine was used to encapsulate silica nanoparticles through the oxidative polymerization of diphenylamine in the presence of ultrasonic irradiation. The polymerization was performed in the presence of sodium lauryl sulfate as a surfactant. Experiments performed in the absence of ultrasound clearly demonstrated that the application of ultrasonication played multiple roles in the preparation of a composite of polydiphenylamine with silica nanoparticles. Ultrasonication dispersed the silica nanoparticles, converted sodium lauryl sulfate to lauryl alcohol, and augmented the dispersion of the silica‐nanoparticle/polydiphenylamine composite in an organic medium. Silica‐nanoparticle/polydiphenylamine composites were also prepared in the absence of ultrasound and/or sodium lauryl sulfate. The silica‐nanoparticle/polydiphenylamine composites were characterized with Fourier trans form infrared spectroscopy, ultraviolet–visible/near‐infrared spectroscopy, and thermogravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3912–3918, 2006 相似文献