bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stabilizer reactions in cast double base rocket propellants. Part VII: Effect of lead‐based ballistic modifiers on the reactions of propellant stabilizers during simulated aging of cast double base solid propellants
Authors: Bellamy A. J. , Bellerby J. M. , Sammour M. H. 
Published: December 2004

AbstractThe effect of lead‐based ballistic modifiers on the reactions of stabilizers during accelerated aging at 80°C and 90°C of cast double base propellants has been investigated in order to obtain information on the reactions taking place in these propellant systems. It was found that the ballistic modifiers lead β‐resorcylate (LBR) and lead salicylate (LS) have a significant effect on the depletion of para‐nitro‐N‐methylaniline (pNMA) and 2‐nitrodiphenylamine (2NDPA). Model studies have shown that both LBR and LS reduce the rate of depletion of pNMA to a similar degree, but only LBR reduces the rate of depletion of 2NDPA, with LS having the opposite effect.
A Simple Method for Calculating Sympathetic Detonation of cylindrical, cased explosive charges
Authors: Victor Andrew C. 
Published: December 2004

AbstractSympathetic detonation involves the propagation of detonation between individual explosive‐containing devices. When many such devices are stored together, the possibility of mass propagation exists. With mass propagation, the entire stored mass detonates nearly simultaneously. Such propagation is the most feared hazard of such explosive items in transportation and storage environments because of its potential for sudden extreme damage and loss of life. Safety requirements, including those for insensitive munitions, are best met if explosive devices can be designed to minimize the risk of sympathetic detonation.This paper presents a simple method for predicting the marginal conditions at which sympathetic detonation of cylindrical munitions just occurs (or just fails). The method can be easily and rapidly used in preliminary design studies to minimize subsequent hazard risks. It allows design and safety engineers to examine in minutes or hours what would take weeks or months of hydrocode calculations and months or years of field testing. The method involves algebraic solution of two‐dimensional shock propagation effects in an extension of Ferm and Ramsay's method for predicting shock initiation by spherical impactors(1). The donor case expansion velocity is calculated using the well‐known Gurney formula for cylinders as amplified by Dehn(2). The calculated initiation behavior of the acceptor charge(s) requires input data from wedge test results in the familiar Pop plot form, although a combination of card‐gap test data and failure diameter data can also be used (with reduced reliability) as a basis for estimating the Pop plot. The calculated results compare well with both hydrocode calculations and test data.
A facile pressing technique for the preparation of small calibre dual role explosive charge
Authors: Kumar A. S. , Samudre S. S. , Waghmare N. G. , Gharia J. S. 
Published: December 2004

AbstractSmall calibre shaped charges are prepared by the pressing method. The shaped charge performance is considerably influenced by the density gradient which is an inherent drawback associated with the pressing method. A new method, double action pressing technique has been developed which overcomes this problem and is amenable for large scale production. Properties of the charges prepared by the different methods especially with respect to the den sity gradient and performance against targets are presented and discussed.
Shock Consolidation of Aluminium Powder with SiC fiber reinforcement
Authors: Böttger W. , de la Haye J. , Prümmer Rolf 
Published: December 2004

AbstractFor the explosive compaction of Al 2024 alloy powder the influence of E/M ratio and detonation velocity of the explosive as well as the influences of powder microhardness and initial density are discussed. With a choice of parameters that gives a fully compacted aluminium sample the results of embedding single SiC fibers are described and a procedure to avoid fiber cracking due to shock loads is derived. First results for the compaction of samples with 38% fiber content are presented.
Combustion Mechanism of Glycidyl Azide Polymer
Authors: Hori Keiichi , Kimura Motoyasu 
Published: December 2004

AbstractA combustion model of glycidyl azide polymer (GAP) is presented. Linear burning rate and temperature profile measurements of model samples led us to the conclusion that linear burning rate is controlled by N2 liberation process below the pressure exponent break point (2.3 MPa). Further, scanning electron microscope (SEM) photographs and Fourier transform infrared (FTIR) spectra of quenched samples by rapid depressurization of the combustor show that the N2 liberation process is strongly limited to the melt layer at the combustion surface and the profile of the heat release rate is probably δ‐function like. This fact enables the application of an asymptotic analysis to this phenomenon.
Initiation Criteria of High Explosives at different projectile or jet densities
Authors: Held Manfred 
Published: December 2004

AbstractTest results of initiation threshold values with tungsten spheres of different diameters d and Lexan spheres of 76 mm diameter can be very well described by the u2d‐Held‐criterion where u is the cratering velocity or \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm v/(1 + }\sqrt {\varrho _{\rm t} /\varrho _{\rm p})} $\end{document}. For covered Composition B the initiation threshold value is 23 mm3/μs2. This value fits also shaped charge tests where the high explosive charge is also in a covered arrangement.
Optimization of the Flow Rate in High Pressure Liquid Chromatography of explosives
Authors: Kaiser Manfred 
Published: December 2004

AbstractThe height of a theoretical plate of 7 nitroaromatic substances and 2 aliphatic explosives was determined in dependence on the flow rate. The optimal flow rate for the maximum of the number of theoretical plates is in the area of 0.4 to 0.6 ml/min. For difficult separations this should be considered, since most HPLC instruments are used in the area of 0.7 to 1.0 ml/min. The amount of theoretical plates was calculated and presented in dependence of the flow rate. The height of a theoretical plate was plotted against the retention time and the capacity factor. The optimal area for the separation of the substances was at a capacity factor of 2 to 10. The van Deemter equation and the Knox equation were adjusted using 2,4‐dinitrotoluene. The data were fitted iteratively and the constants were determined. The equation for the conversion of the flow rate for other column diameters was shown, and using an example, the dependence of the flow rate on the column inner diameter and the flow rate was presented graphically.
Insensitive munitions (IM) and combustion characteristics of GAP/AN composite propellants
Authors: Oyumi Yoshio , Kimura Eishu , Hayakawa Shigeyuki , Nakashita Goro , Kato Kazushige 
Published: December 2004

AbstractSensitivities to the ballistic shock and burn rate characteristics of GAP/AN composite propellants were investigated. Nitrate esters, such as TMETN and NC, were very effective ballistic modifier that provided useable burn rate and pressure rate exponent for minimum signature propellant based on AN. Their low temperature mechanical properties became less sensitive to the temperatures with nitrate esters. Dioctyl adipate platicized propellant showed excellent mechanical properties at operational temperature ranges. The primary initiation mechanism of card gap test was not dominated by the mechanical properties. Although NC significantly increased the critical shock pressure, 14.8% HMX and AP were less effective to the sensitivities. GAP/AN propellants showed excellent IM characteristics to the ballistic shock applied here.
Ethical reflections on herbicide‐resistant crops
Authors: Madsen Kathrine Hauge , Sandøe Peter 
Published: December 2004

AbstractThe introduction of genetically modified (GM) crops has caused a fierce public debate in Europe. Much of the controversy centres on possible risks to the environment. A specific problem here is that risk perception of the scientific experts differs from that of the public. In this paper, risks associated with herbicide‐resistant crops are presented from the point of view of experts and lay people. In the public perception, herbicide‐resistant (HR) crops are troublesome because of their association with two technologies: genetic engineering of crops and the use of herbicides. These technologies are perceived as risky because they seem to share certain features: in particular, their long‐term effects are unknown and they are dreaded. Other value questions also come into play. The public seems to be concerned that risks are not outweighed by usefulness, that using HR crops is the wrong path to sustainable agriculture, that the individual's right to choose GM‐free products may be violated, and that these crops are unnatural. In contrast, on the issue of the uncertainty inherent in risk assessment, experts and the public seem to share a good deal of ground. Copyright © 2005 Society of Chemical Industry
A comment on the super‐secular‐equation in a symmetry adapted basis
Authors: Amos A. T. 
Published: December 2004

AbstractThe super‐secular‐equation has been introduced by Löwdin to discuss the Schrödinger equation in terms of a linearly dependent basis. The method is shown to be particularly simple when the basis is a symmetry adapted one. By expanding the secular equation a formula giving a good estimate of the eigenvalue is obtained.
Some remarks on the core resonance integral as used in the semi‐empirical π‐electron calculations
Authors: Sannigrahi A. B. 
Published: December 2004

AbstractA simple semi‐theoretical expression for β, the core resonance integral as used in the semi‐empirical π‐èlectron calculations has been proposed. β's for some standard C  C and C  0 lengths have been evaluated with the proposed formula and the calculated values are compared with those obtained by other semi‐theoretical and empirical methods. Electronic spectra of ethylene, formaldehyde, trans‐butadiene and benzene have been calculated by a Pariser‐Parr‐like semi‐empirical method with the values of β thus obtained. The calculated spectra are found to be in good agreement with the observed ones.
A separated‐electron pair study of the electronic structure of the Li2O molecule
Authors: Lin Teng Ke , Ebbing Darrell D. 
Published: December 2004

AbstractA separated pair calculation of the electronic structure of the Li2O molecule is described. Rather extensive calculations were made of the potential surface for symmetric configurations of Li2O using a double zeta Slater orbital basis. A linear configuration with LiO bond length of 1.71 Å is found to be most stable. The electron distribution and correlation effects are discussed.
The MC SCF theory: Method of one‐electron Hamiltonian
Authors: Kuprievich V. A. , Shramko O. V. 
Published: December 2004

AbstractThe one‐electron Hamiltonian method is developed to solve the variational equations of the MC SCF theory.The many‐parameter family of the one‐electron Hamiltonian is derived and conditions for parameters to provide convergence of the SCF procedure to the energy minimum are obtained. A computation scheme based on the use of the one‐electron Hamiltonian is described.
Variational bounds for imaginary frequency polarizability and dispersion interaction constant
Authors: Braun P. A. , Rebane T. K. 
Published: December 2004

AbstractA study is made of a variational principle which provides upper and lower bounds for the polarizability under a perturbation with imaginary frequency. As an example bounds for the imaginary frequency polarizability of atomic hydrogen and ensuing limits for the constant of van‐der‐Waals interaction of two hydrogen atoms are calculated.
Theoretical studies of diamagnetic properties of the hydrogen molecule ion II. Effect of varying internuclear separation
Authors: Garrett Thomas B. , Zeroka Daniel 
Published: December 2004

AbstractThe diamagnetic susceptibility χ and magnetic shielding σ for H are investigated in the range of internuclear separations R = 1.6 a.u. to R = 2.4 a.u. according to a previously reported technique. From this data values of 〈χ〉 and 〈σ〉, for which nuclear motion due to zero‐point vibration and centrifugal stretching is taken into account, are calculated at 300°K. These averages are 〈χ〉 = −0.3902 α2a and 〈σ〉 = 1.096 × 10−5 c.g.s. units which are approximately 3.1% and 1.4% respectively, smaller than the equilibrium values.
Simple perturbation and perturbation‐variation treatments of the 1sσg and 2pσu states of H
Authors: Tung Eleanor W. , Sanders William A. 
Published: December 2004

AbstractFirst‐order wave functions and binding energies of the 1sσg and 2pσu states of H are calculated by simple methods for internuclear separations between 0.2 and 10a0. An exact perturbation treatment of the lsσg state with a zeroth‐order function of the form N exp (‐sRλ/2) exp (sR μ2) yields only fair results. An alternative method starts with zeroth‐order functions of the form N exp (‐sRλ/2)[exp (‐sRμ/2) ± exp (sRμ/2)] for the 1 and 2 states, respectively. An approximate first‐order trial function is set up and the energies are determined variationally. For both states the results are comparable to those obtained by exact perturbation treatments of the same order.
Molecular orbitals of zinc phthalocyanine
Authors: Mathur S. C. , Singh Jai 
Published: December 2004

AbstractMolecular orbitals of zinc phthalocyanine have been calculated with the help of a kind of extended Hückel technique. Coulomb and exchange integrals of the zinc atom have been approximated in a way equivalent to the valence state ionization energies of the particular metal orbital for a particular charge configuration. π‐electron charge densities over the atomic sites have been calculated and found in agreement with the observed results. π‐π* absorption (11000 cm−1 − 32000 cm−1) and charge transfer absorption (19000 cm−1 − 40000 cm−1) frequencies have also been calculated and found in agreement with the experiment.
An application of Green's functions to the study of the vibration‐translation coupling of trapped oscillators in a linear chain
Authors: Blaisten‐Barojas E. , Allavena M. 
Published: December 2004

AbstractThe Green functions and Kubo linear‐response theory are used to calculate the absorption coefficient of a collection of diatomic molecules embedded in a one‐dimensional lattice. The effect of the environment is restricted to the coupling between the molecular internal vibration and lattice vibrations. For the molecular oscillators, both harmonic and anharmonic models are considered. The absorption line shape is expressed in closed form whether the molecular frequency falls outside or within the allowed phonon frequency range. In both cases a frequency shift is found. In the anharmonic case there is a broadening of the absorption lines. Expressions for the shift and line width are given.
Sequence‐adapted molecular tensors: Algebraic methods and application to crystal field theory
Authors: Ellzey M. L. 
Published: December 2004

AbstractTensorial sets adapted to sequences of finite subgroups are applied to the crystal field problem, and a general method for generating sequence‐adapted molecular tensors using finite group algebra is formulated. All subgroup sequences of the abstract finite group G(24), isomorphic to the octahedral, O, tetrahedral, Td, and symmetric, S(4), groups are tabulated with explicit isomorphisms provided. The sequences fall into eight equivalence classes. A catalog of irreducible representations of G(24) adapted to a member of each of the eight sequence classes is given together with the transformations which generate representations adapted to all other sequences. With this data it is possible to systematically generate tensorial sets adapted to any sequence of a realization of G(24). Unitary transformations which adapt conventional forms of first‐ and second‐rank irreducible tensorial sets of the rotation group to the eight sequences of the octahedral group are provided. Forms suitable for use with magnetic fields are included. The problem of a d1 ion in a trigonal crystal field is treated with sequence‐adapted molecular tensors, and the utility of different sequences for descent in symmetry is discussed.
Integrals of quantum chemical interest in bases of laguerre functions. I. Functions of order 2l+2
Authors: Moseley W. D. 
Published: December 2004

AbstractFormulae are presented for the evaluation of some definite integrals in which the Laguerre orthogonal functions are contained. In some cases mechanical quadratures are to be preferred, and a scheme is presented for generating such a quadrature as it is needed.
Tunneling phenomena in three‐dimensional double‐well potentials
Authors: Carbonell R. G. , Kostin M. D. 
Published: December 2004

AbstractThe tunneling of a hydrogen atom through the barrier of a three‐dimensional double‐well potential is considered. From the time‐dependent Schrödinger equation, expressions are derived for the ensemble‐averaged probability density and for the probability that the hydrogen atom is in the reactant region, in the barrier region, or in the product region. It is found that when thermal vibrations are not taken into account, the ensemble‐averaged probability density may oscillate with time about its equilibrium value. When thermal vibrations are included, the oscillations become damped and the probability density approaches equilibrium. The tunneling rate is found to decrease considerably for increasing barrier thickness and barrier height.
Icosahedral irreducible tensors and their applications
Authors: Boyle L. L. , Ożgo Z. 
Published: December 2004

AbstractAfter a discussion of different concepts of anisotropy with reference to the icosahedron, the unusual problems surrounding the construction of icosahedral irreducible tensors are discussed. Tables of these tensors are then presented and applied to orbital problems, molecular polarization phenomena and to the construction of projection operators.
Half‐Projected and Projected Hartree‐Fock Calculations for Singlet Ground States. i. four‐Electron Atomic Systems
Authors: Smeyers Yves G. , Doreste‐Suarez L. 
Published: December 2004

AbstractThe half‐projected Hartree‐Fock function (HPHF) for singlet states is defined as a linear combination of two Slater determinants, which contains only spin eigenfunctions with even quantum number. Using a self‐consistent procedure based on the generalized Brillouin's theorem, the RHF, HPHF and PHF functions are deduced for the ground states of the Li−, Be, B+, and C2+ systems, in a limited basis set. It is found that the HPHF function yields better energy values than the RHF function, very close to that of the PHF one. The HPHF scheme seems thus to be useful as a substitute for the PHF model, specially in the case of large electronic systems in which the latter method becomes unmanageable.
Group theoretical methods for determining permitted terms of the electronic states of complexes in crystals. III. The use of plethysm for classification of the permitted terms of impurity complexes in crystal
Authors: Men B. A. , Cherepanov V. L. , Men A. N. 
Published: December 2004

AbstractA procedure for the use of the plethysm operation for classification of the permitted electronic terms of impurity complexes in a crystal is presented. The cases of polyatomic symmetrical complexes are discussed as examples.
Molecular orbital studies on small molecules using H2+‐type elliptical basis orbitals. Application to H2+, H2, He2++ and H3+
Authors: Llaguno Claro T. , Gupta Shiv K. , Rothstein Stuart M. 
Published: December 2004

AbstractH2+‐type elliptical orbitals are defined in Section 1. These orbitals, which in elliptical coordinates involve a factor (1 + ξ)σ, are employed in variational calculations on the ground states of H2+ and H2 (Sections 2 and 3). Various choices of σ are explored for H2+, while two choices are used for H2 : the “boundary condition” (Equation 6) and the “cusp condition” (Equation 9) values. Variational energies are calculated and compared to the results of similar calculations. Section 3 concludes by employing the H2+‐type orbitals in LCETO‐MO‐SCF calculations on the ground states of H2 and He2++. For both molecules a four‐function basis set with two (nonlinear) variational parameters yields more than 99% of the Hartree‐Fock limit. Section 4 deals with LCETO‐MO‐SCF calculations on triangular H3+. Three four‐function basis sets are used, and the best energy is ‐1.2306 a.u., which is in reasonable agreement with the Hartree‐Fock limit, ‐1.2999 a.u. Our best basis set is a four‐term two‐center expansion of the wave function with only one nonlinear variational parameter. Section 5 concludes the paper with a summary of the methods used to evaluate the integrals which arise in SCF calculations in the H2+‐type elliptical orbital basis.
Matrix elements for spin‐adapted configurations
Authors: Davidson Ernest R. 
Published: December 2004

AbstractIt is shown that the turn‐over rule which is used to simplify matrix elements between spin‐projected Slater determinants may also be used to simplify formation of matrix elements between any orthonormal set of spin‐coupled Slater determinants. The coefficients for the spin‐coupling may then be chosen freely to reduce the number of important configurations in the secular equation.
An investigation into the use of expansion methods in the calculation of chemical shifts and diamagnetic susceptibilities
Authors: Emanuel R. V. 
Published: December 2004

AbstractThe chemical shift and the diamagnetic susceptibility of the hydrogenic atom with magnetic dipole and origin of the external magnetic field vector potential noncoincident with the hydrogenic nucleus have been calculated from perturbation theory using a set of expansion functions whose radial parts are single exponent associated Laguerre functions. In contrast to hydrogenic expansion functions these functions give rapid convergence to the exact values of the second‐order energy summations when centred at the hydrogenic nucleus. The rate of convergence is fairly insensitive to the choice of expansion function exponent.
Electron correlation study for two‐electron atoms by a simple correlated wave function
Authors: Kagawa Takashi , Murai Tomokazu 
Published: December 2004

AbstractThe difference in the electron correlation between H‐ and other two‐electron atoms is clarified by the introduction of the r12 term in the wave function. By using the expansion of r12, a certain modification of the usual electron correlation factor 1 + Cr12 is introduced and its effectiveness is examined. Calculations are carried out for the ground state and the three lowest excited states (23S, 23P and 21P). The peculiar electron correlation in the ground state of H− is shown by looking at the Coulomb hole for closed‐ and open‐shelf models in comparison with those for other two‐electron atoms.
Dual‐basis orthonormality‐constrained variation method
Authors: Narita Susumu , I'haya Y. J. 
Published: December 2004

AbstractThe method of orthonormality‐constrained variation is extended using a dual‐basis set instead of a single orthonormal basis. The complete and the partial variation methods are discussed and applied to electronic systems. It is found that the present formulation leads to the most general equation in the coupling operator method.
Effective operators and the Z‐expansion method
Authors: Minchin P. E. H. , Wybourne B. G. 
Published: December 2004

AbstractThe application of effective operators in the Z‐expansion method is explored using hydrogenic functions. The relevant perturbation summations are evaluated using unit tensor operators and the results applied to the 1s22s22p2 + 1s22p4 complex of the carbon isoelectronic series.