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21.
Werner Georg Nowak 《manuscripta mathematica》1982,39(2-3):277-285
Let G (R) denote the number of lattice points (,) **Z2 in the domain B(R) bounded by the lemniscate (x2+y2)2=2R2 (x2–y2) and put P(R)=G(R)-R2(R2 being the area of B(R)). The purpose of this paper is to determine the order of magnitude of P(R) for large R by proving the asymptotic relation (3). An analogous result is given for the eight curve x4=R2 (x2–y2). 相似文献
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Bismuth Monoiodide, a Compound with Bi(O) and Bi(II) Bismuth monoiodide was synthesized in closed tubes from the elements as well as from Bi and HgI2 as a black coloured crystalline compound. With increasing temperature BiI passes two transitions. α-BiI is stable below 370 K and changes to β-BiI by a martensitic transition. γ-BiI is the stable modification above 564 K and decomposes at 585 K peritectically to BiI3 and a lower iodide. All three modification crystallize in the monoclinic space group C2/m. The structures (single crystal studies) of α-BiI and β-BiI are characterized by onedimensional infinite chains [Bi4I4] with covalent bonds but only weak interactions in between. The [Bi4I4]-chains are built up by two completely different Bi atoms. Bi(A) is only bonded to three Bi whereas Bi(B) has bonds to one Bi and four I. The average bond lengths are Bi? Bi = 304.5 pm and Bi? I = 313.7 pm respectively. The configuration of the Bi(A) atoms is typical for BiO and that one of the Bi(B) atoms is characteristic for Bi2+ with the electron configuration s2p1. Therefore, α-BiI and β-BiI are mixed valence compounds [BiOBi2+I4]. The structures are variants of the simple cubic polonium type of structure and differ in the stacking of connected units. The structures and their transitions, the possible configurations for monohalides BiX on principle as well as the energy balances of the disproportionation of Bi+ are discussed together in detail. 相似文献
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气化是实现化学利用碳资源(尤其是煤)生产化学品和燃料的关键工艺.目前,全球拥有超过272套气化装置,主要应用于煤化工,尤其在中国.由于在一个化工厂通过技术集成达到工业规模的集中生产可实现减少二氧化碳排放并促进碳密集型行业的循环经济,如废物管理、化学和交通行业,因此,近年来全球对垃圾气化的兴趣日益浓厚,尤其是那些在煤气化... 相似文献
26.
Georg Steinhauser Stefan Merz Johannes H. Sterba 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):165-168
We present and discuss a modification of instrumental neutron activation analysis (INAA) that is sensitive for nuclides that do not yield (suitable) activation products but have high cross sections for neutron absorption. Their presence in a sample may thwart INAA by neutron flux suppression inside the sample, but they remain undetected and thus unnoticed by the analyst. In particular, this refers to Li, B, Cd and Gd. The proposed method—instrumental neutron absorption activation analysis (INAAA)—takes advantage of the flux depression inside the sample caused by the neutron absorbers. It is made visible by addition of an activatable nuclide (indicator). The concentration of the neutron absorber (analyte) causes a decrease in activity of the indicator. The activity difference between a mixed sample (sample plus indicator) and the pure indicator carries the analytical information. The calibration curve hence follows a reciprocal exponential function. In a proof-of-principle experiment, the applicability for the quantification of boron was exemplified. In presence of only one neutron absorber (whose nature is known), INAAA can be applied easily for quantification of the analyte in powdered or liquid samples. Although INAAA is no trace sensitive method, it has the potential to increase the reliability of INAA analyses by fast and straightforward quality control (even in presence of two or more neutron absorbing nuclides). It is especially suited for research reactors that do not operate a prompt gamma neutron activation analysis (PGNAA) station. 相似文献
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Modelling, simulation and optimal control for a lithium-ion battery cell is discussed. The model involves ionic concentrations, currents and potentials in the electrodes and the separator together with the battery temperature as state variables. The resulting system is a nonlinear PDAE system with 10 partial, 1 ordinary differential and 4 algebraic equations involving the Butler-Volmer kinetics for describing the interaction of ionic currents and potentials. Time-optimal charging of the battery subject to age-preventing leads to a state-constrained optimal control problem which is solved in two ways. A first-discretize-then-optimize approach leads to a high-dimensional nonlinear optimization problem which is solved by an efficient solver. As an alternative, a feedback control law along an active arc of the state constraint of order 1 is derived to formulate and solve the corresponding so-called induced optimization problem. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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