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31.
32.
A mathematical model is proposed for the process of vacuum superplasticforming. The model exploits the fact that in most industrialapplications the sheet aspect ratio (thickness/sheet width)is small. After an initial consideration of some of the moregeneral properties and the literature of superplastic materials,the elastic/plastic deformation of an internally-inflated thin-walledcylinder is examined. Plates of arbitrary geometry are thenconsidered. A quasisteady model in which the sheet moves througha sequence of steady states is developed. Some simplified closed-formsolutions are examined, but for general cases a system of nonlinearpartial differential equations must be solved numerically. Anefficient and accurate semi-explicit numerical scheme is proposedand a simplified stability analysis is presented; the methodis then used to compute properties of superplastic vacuum mouldedsheets in a number of practically motivated cases. 相似文献
33.
Benjamin Klopsch 《Israel Journal of Mathematics》2003,137(1):265-284
Let Σ denote the class of allnon-abelian finite simple groups. We are concerned with enumerating poly-Σ groups, that is finite groups without abelian composition
factors. For any natural numbern let gΣ(n) denote the number of (isomorphism classes of) poly-Σ groups of order at mostn. We determine the growth rate of the sequence gΣ(n),n ε ℵ.
Similarly, for anyS ε Σ we give estimates for the numbers ĝS(k) of poly-S groups of composition length at mostk, ask tends to infinity. This initiates an investigation somewhat complementary to the “classical” enumeration of finitep-groups by Higman [6] and Sims [15].
Our ancillary results include upper bounds for the minimal number of generators and for the number of (equivalence classes
of) permutation actions of any given poly-Σ group. 相似文献
34.
The true potential energy curves forX
1
Σ
+, a3
π
r,A
1
π,e
3
Σ
−,E
1
Σ
+,c
3
π
i states of astrophysically important molecule SiO, whose spectra were observed in the sunspots, have been constructed using
the method of Lakshman and Rao. Dissociation energy and ionization potential have been estimated as 65,350 cm−1 and 92,854 cm−1 respectively and found to be in good agreement with the values cited in literature.
The true potential energy curves forX
1
Σ
+,D
1
π andE
1
Σ
+ states of SiS molecule have been constructed by the same method and its dissociation energy in the ground state has been
estimated using Hulburt-Hirschfelder potential function as 54,765 cm−1 in good agreement with 53,250.9 cm−1 given by Herzberg. 相似文献
35.
36.
Solid bisphenol-A epoxy
resin of medium molecular mass was cured using a Lewis acid initiator (ytterbium(III)
trifluoromethanesulfonate) in three different proportions (0.5, 1 and 2 phr).
A kinetic study was performed in a differential scanning calorimeter. The
complete kinetic triplet was determined (activation energy, pre-exponential
factor, and integral function of the degree of conversion) for each system.
A kinetic analysis was performed with an integral isoconversional procedure
(free model), and the kinetic model was determined both with the Coats-Redfern
method (the obtained isoconversional value being accepted as the effective
activation energy) and through the compensation effect. All the systems followed
the same isothermal curing model simulated from non-isothermal ones. The growth-of-nuclei
Avrami kinetic model A3/2 has been proposed as the
polymerization kinetic model. The addition of initiator accelerated the reaction
especially when 2 phr was added. 0.5 and 1 phr showed very few kinetic differences
between them. 相似文献
37.
Benjamin Klopsch 《Archiv der Mathematik》2011,96(4):321-333
The rank of a profinite group G is the basic invariant \({{\rm rk}(G):={\rm sup}\{d(H) \mid H \leq G\}}\), where H ranges over all closed subgroups of G and d(H) denotes the minimal cardinality of a topological generating set for H. A compact topological group G admits the structure of a p-adic Lie group if and only if it contains an open pro-p subgroup of finite rank. For every compact p-adic Lie group G one has rk(G) ≥ dim(G), where dim(G) denotes the dimension of G as a p-adic manifold. In this paper we consider the converse problem, bounding rk(G) in terms of dim(G). Every profinite group G of finite rank admits a maximal finite normal subgroup, its periodic radical π(G). One of our main results is the following. Let G be a compact p-adic Lie group such that π(G) = 1, and suppose that p is odd. If \(\{g \in G \mid g^{p-1}=1 \}\) is equal to {1}, then rk(G) = dim(G). 相似文献
38.
Steiner WE Harden CS Hong F Klopsch SJ Hill HH McHugh VM 《Journal of the American Society for Mass Spectrometry》2006,17(2):241-245
The use of negative ion monitoring mode with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer [IM(tof)MS] to detect chemical warfare agent (CWA) degradation products from aqueous phase samples has been determined. Aqueous phase sampling used a traditional electrospray ionization (ESI) source for sample introduction and ionization. Certified reference materials (CRM) of CWA degradation products for the detection of Schedule 1, 2, or 3 toxic chemicals or their precursors as defined by the chemical warfare convention (CWC) treaty verification were used in this study. A mixture of six G-series nerve related CWA degradation products (EMPA, IMPA, EHEP, IHEP, CHMPA, and PMPA) and their related collision induced dissociation (CID) fragment ions (MPA and EPA) were found in each case to be clearly resolved and detected using the IM(tof)MS instrument in negative ion monitoring mode. Corresponding ions, masses, drift times, K(o) values, and signal intensities for each of the CWA degradation products are reported. 相似文献