/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1080/00207540600905646International Journal of Production Research, 46, 4, pp. 967-992, 2007-05-17 Reconfigurable manufacturing systems: the state of the art Bi, Z.; Lang, S.; Shen, W.http://www.nrc-cnrc.gc.ca/irc Re c onfigura ble m a nufa c t uring syst e m s: t he st a t e of t he a rt IMTI-XP-530Bi, Z.; Lang, S.; Shen, W. May 2007A version of this document is published in / Une version de ce document se trouve dans:International Journal of Production Research, 46, (4), pp. 967-992, May 17, 2007, DOI: 10.1080 The material in this document is covered by the provisions of the Copyright Act, by Canadian laws, policies, regulations and international agreements. Such provisions serve to identify the information source and, in specific instances, to prohibit reproduction of materials without written permission. For more information visit http://laws.justice.gc.ca/en/showtdm/cs/C-42Les renseignements dans ce document sont protégés par la Loi sur le droit d'auteur, par les lois, les politiques et les règlements du Canada et des accords internationaux. Ces dispositions permettent d'identifier la source de l'information et, dans certains cas, d'interdire la copie de documents sans permission écrite. Pour obtenir de plus amples renseignements : http://lois.justice.gc.ca/fr/showtdm/cs/C-42 Abstract: In this paper, general requirements of next generation manufacturing systems are discussed, and the strategies to meet these requirements are considered. The production paradigms which apply these strategies are also classified. Particular emphasis is put on the paradigm of Reconfigurable Manufacturing System (RMS). Some key issues of the RMS design are discussed, and a critical review is presented concerning the developments of RMSs. Finally, suggestions of the RMS research are made and future research directions are identified. Reconfigurable Keywords: Reconfigurable Manufacturing Systems (RMS),system architecture, system configuration, Open Architecture Control (OAC), reconfigurability, modularity IntroductionDue to excessive production capability and economic globalization, the manufacturing environment becomes turbulent and uncertain. Manufacturing enterprises are forced to reassess their production paradigms, so that a manufacturing system can be designed and operated efficient...

A general correlation for the 129 Xe NMR chemical shift-pore size relationship (δ versus D) in porous silica-based materials over the range 0.5-40 nm has been demonstrated: δ ) δs/(1 + D/b), with δs ) 116 ( 3 ppm and b ) 117 ( 8 Å for the 34 materials studied. The correlation may be used in the characterization of silica samples with unknown pore structure. Even within this general correlation, subsets of materials of similar origin display finer correlations that indicate an acute sensitivity to details of the pore surfaces.The NMR spectroscopy of adsorbed 129 Xe has evolved into a sophisticated scientific tool for the study of different aspects of the structure and topology of internal voids in porous substances. 1 Although some disadvantages of the technique have been noted, 2 it remains attractive and popular, as judged by the fact that in 2001 about 50 Xe NMR-related papers were published. The latest improvements include the production of hyperpolarized xenon (HP Xe), 3 which gives a dramatic increase in the sensitivity for a variety of applications. 4 Besides such practical novelties, important theoretical developments directed at a much needed understanding of chemical shielding phenomena of confined 129 Xe are in progress. 5 For example, through empirical correlations were proposed between isotropic Xe chemical shifts and the pore size (δ-D correlation) in zeolites 6a as well as clathrates and solid Xe, 6b there is still no clear quantitative appreciation of the origin of this behavior. Attempts to extend it beyond zeolites have failed, and it has been pointed out that different correlations must exist for small pores, with a diameter less than about twice the diameter of a Xe atom, and large pores, as in the latter case account must be taken of Xe not adsorbed on the pore walls. 7We have shown previously that a simple fast exchange model explains a qualitatively similar, yet distinct, δ-D correlation found for mesoporous amorphous silica gels with a wide range of mean pore diameters from 2 to 40 nm. 8 Assuming that the 129 Xe NMR chemical shift of xenon adsorbed in mesoporous silica is a dynamic average between the gas and adsorbed states, it is straightforward to derive a parabolic dependence of the 129 Xe NMR chemical shift, δ (ppm), on the mean pore diameter, D (Å), where δ s is the chemical shift characteristic of interactions of Xe with the silica surface, and the parameter b depends on the pore geometry (η), the adsorption constant (K), and the temperature (T), as 8The mean pore diameter (D) is usually given through the volume-to-surface ratio as D ) ηV/S, where the geometry factor η is dependent on the model adopted for the pores. It can vary from 2.8 in a model of randomly packed globular particles (D ) 2.8V/S), to 4 for cylindrical pores (D ) 4V/ S) or 6 for unconnected spherical pores (D ) 6V/S).In this work we show that the model is more generally applicable by extending the range of silica-based porous materials, and we illustrate the correlation with previous work 8, 9 and new results 10 on...

This work reports significantly improved spectral resolution of (13)C CP MAS NMR spectra of chlorinated, brominated and iodinated solid organic compounds when such spectra are recorded at ultrahigh magnetic field strengths. The cause of this is the residual dipolar coupling between carbon atoms and quadrupolar halogen nuclides (chlorine-35/37, bromine-79/81 or iodine-127), an effect inversely proportional to the magnetic field strength which declines in importance markedly at 21.1 T as compared to lower fields. In favorable cases, the fine structure observed can be used for spectral assignment, e.g. for Cl-substituted aromatics where the substituted carbon as well as the ortho-carbons show distinct doublets. The experimental results presented are supported by theoretical modeling and calculations. The improved spectral resolution in the studied systems and similar halogenated materials will be of particular interest and importance for polymorph identification, drug discovery and quality control in the pharmaceutical industry.

Depending on the details of the technique employed, desolvation of tBC inclusion compounds leads to either a dense, guest-free polymorph, or a guest-free low density polymorph, the latter also having distinct high and low temperature forms.

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The spectroscopic investigation of CO(2)-containing clathrate hydrates is complicated because techniques such as Raman spectroscopy cannot distinguish cage populations. (13)C NMR spectroscopy also has some complications as the isotropic chemical shifts do not change for the different CO(2) cage populations. It is known that CO(2) molecules in the different phases relevant to hydrates give unique infrared vibrational frequencies; however, so far only thin cryogenic films prepared at low pressure have been studied with IR transmission spectroscopy. In this study, hydrates from CO(2), CO(2)/H(2), and CO(2)/H(2)/C(3)H(8) mixtures were synthesized in a high-pressure attenuated total reflection (ATR) cell and in situ infrared spectroscopy was performed at -50 degrees C to distinguish the vibrational frequencies from CO(2) in small and large cages in the resultant hydrate and in the other CO(2)-containing phases. Quantitative estimates of cage occupancies and hydration numbers are provided as based on the analysis of the IR spectra and knowledge of hydrate gas composition from gas chromatography.

129Xe NMR spectroscopy with a continuous flow of dilute hyperpolarized xenon directed into the sample region of an NMR probe (either static or spinning) allows the rapid recording of spectra that are characteristic of the void space in micro- and mesoporous solids. The high sensitivity of the method allows the time-resolved, in-situ monitoring of processes involving sorbents such as activation, adsorption, and desorption.

Detailed knowledge of the wind resource is necessary in the developmental and operational stages of a wind farm site. As wind turbines continue to grow in size, masts for mounting cup anemometers-the accepted standard for resource assessment-have necessarily become much taller, and much more expensive. This limitation has driven the commercialization of two remote sensing (RS) tools for the wind energy industry: The LIDAR and the SODAR, Doppler effect instruments using light and sound, respectively. They are ground-based and can work over hundreds of meters, sufficient for the tallest turbines in, or planned for, production. This study compares wind measurements from two commercial RS instruments against an instrumented mast, in upland (semi-complex) terrain typical of where many wind farms are now being installed worldwide. With appropriate filtering, regression analyses suggest a good correlation between the RS instruments and mast instruments: The RS instruments generally recorded lower wind speeds than the cup anemometers, with the LIDAR more accurate and the SODAR more precise.