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1.
Jaromir Zajac Frantisek Zacek Vojtech Lejsek Zbynek Brettschneider 《Fusion Engineering and Design》2007,82(4):369-379
The Compass-D tokamak is being planned to move from UKAEA Culham (England) be and reinstalled in IPP Prague (Czech Republic). An overview of Compass-D energetics is described in short. The new power sources have to be designed. Alternative solutions of power sources have been investigated. Ignitrons and mechanical breakers can be replaced by modern high-power semiconductors. With respect to the need of accumulated energy, new technologies of energy storage - supercapacitors and high-speed flywheels, not applied up to now in similar fusion projects, are characterized in comparison with traditional ones - capacitors and big motor-flywheel generators. It is shown that these technologies enhance possibilities in arrangement of power supplies for tokamaks as well as for other high-power demanding experiments with pulse length from fraction to tens of seconds. 相似文献
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In the present paper, we study the nonterminal complexity of one-sided random context grammars. More specifically, we prove
that every recursively enumerable language can be generated by a one-sided random context grammar with no more than ten nonterminals.
An analogical result holds for thirteen nonterminals in terms of these grammars with the set of left random context rules
coinciding with the set of right random context rules. Furthermore, we introduce the notion of a right random context nonterminal, defined as a nonterminal that appears on the left-hand side of a right random context rule. We demonstrate how to convert
any one-sided random context grammar G to an equivalent one-sided random context grammar H with two right random context nonterminals. An analogical conversion is given in terms of (1) propagating one-sided random
context grammars and (2) left random context nonterminals. In the conclusion, two open problems are stated. 相似文献
4.
Poly(styrene-divinylbenzene) monoliths have been hypercrosslinked using a Fe3+ catalyzed Friedel–Crafts reaction involving three external crosslinkers (1) 4,4′-bis(chloromethyl)-1,1′-biphenyl, (2) α,α′-dichloro-p-xylene, and (3) formaldehyde dimethyl acetal. The first crosslinker was found to produce monoliths with the best chromatographic performance. The effects of a number of variables affecting the hypercrosslinking reaction were studied in detail. These variables included: (i) the temperature and time used for polymerization of the precursor monoliths, (ii) the amount and loading procedure of the external crosslinker and catalyst, and, (iii) the temperature and reaction time of the Friedel–Crafts alkylation. Polymers with extremely large surface areas reaching up to 900 m2/g were obtained using a precursor monolith polymerized for only 2.5 h, and hypercrosslinked with 4,4’-bis(chloromethyl)-1,1′-biphenyl. The increased performance of monoliths modified using this new procedure is comparable to the performance obtained with monolithic polymers containing chloromethylstyrene. However, the preparation of the poly(styrene-divinylbenzene) precursor is simpler than that of conterparts containing chloromethylstyrene. The hypercrosslinked monoliths in capillary columns were tested in an isocratic reversed phase liquid chromatography separation using a mixture comprised of acetone and six alkylbenzenes. Column efficiencies for retained analytes exceeded 70,000 plates/m. 相似文献
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The modeling of the unit operation of vacuum contact drying is approached as a multi-scale problem. At the particle assembly length scale, effective transport properties (thermal conductivity, relative gas- and liquid-phase permeability) have been determined computationally by simulations on reconstructed porous media and verified by direct measurements. A distributed-parameter model of vacuum contact drying including liquid and vapor flow and differential energy balance has been formulated and used for the calculation of drying time as function of vacuum level, temperature, vessel diameter, and batch size at the unit operation length scale. Drying curves for a model system of sodium carbonate–isopropanol have been measured experimentally and compared with the model predictions. A very good agreement has been found. 相似文献
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Hynek Biederman Ismail H. Boyaci Petra Bilkova Danka Slavinska Selma Mutlu Josef Zemek Miroslava Trchova Josef Klimovic Mehmet Mutlu 《应用聚合物科学杂志》2001,81(6):1341-1352
Cellulose acetate membranes (CA) were modified by means of plasma polymerization of ethylene diamine (EDA) and n‐butylamine (n‐BA). The motivation for this work was the application of a modified membrane for the single‐layer enzyme electrode. A tubular reactor with the external radiofrequency (13.56 MHz) excitation was used. Surface modification was performed at 5, 10, and 15 W power (at 27 Pa working pressure) for 5, 10, 15 min. Modified surfaces were characterized in detail by FTIR–ATR, XPS (ESCA), contact angle, and enzyme immobilization activity. The best treatment results were obtained for EDA with 5 W and 30 min and 15 W and 10 min. These results are discussed using surface analysis data. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1341–1352, 2001 相似文献
9.
Highly sensitive label-free techniques of DNA determination are particularly interesting in relation to the present development of the DNA sensors. We show that subnanomolar concentrations (related to monomer content) of unlabeled DNA can be determined using copper solid amalgam electrodes or hanging mercury drop electrodes in the presence of copper. DNA is first treated with acid (e.g., 0.5 M perchloric acid), and the acid-released purine bases are directly determined by the cathodic stripping voltammetry. Volumes of 5-3 microL of acid-treated DNA can easily be analyzed, thus making possible the determination of picogram and subpicogram amounts of DNA corresponding to attomole and subattomole quantities of 1000-base pair DNA. Application of this determination in DNA hybridization detection is demonstrated using surface H for the hybridization (superparamagnetic beads with covalently attached DNA probe) and the mercury electrodes only for the determination of DNA selectively captured at surface H. 相似文献
10.
Frantisek Lopot Bohdan Nejedlý Sylvie Sulková 《Hemodialysis international. International Symposium on Home Hemodialysis》2004,8(1):39-44
Quotidian or “daily" hemodialysis (DHD) is practiced in widely differing schedules. Yet all those schedules are reported to significantly ameliorate clinical outcome of patients. It is, however, not clear what is the actual cause of this amelioration. Rational possibilities include increased overall dialysis dose and increased weekly time. Conventional mathematical approaches (Kt/Vurea concept, equivalent renal clearance) cannot be used to study those issues because they do not consider number of dialysis per week and thus ignore the issue of treatment schedule “unphysiology.” The time average concentration/time average deviation (TAC/TAD) concept may well be used to visualize impact of treatment schedule on both plasma urea profile statics (TAC) and dynamics (TAD). The concept may further help to stratify studies for elucidation of the key factors of clinical outcome improvement seen on DHD. Actual physiologic mechanisms responsible for this improvement are to be sought among those with having derivative component (i.e., reacting to the rate of a change rather than to the magnitude of the change). It should, however, be kept in mind that the TAC/TAD concept is able to assess unphysiology of a treatment schedule, not unphysiology of a single treatment session. 相似文献