Showing papers by "Wright-Patterson Air Force Base published in 1969"
TL;DR: In this paper, a bending theory which includes transverse shear deformations was presented for laminated plates and closed form solutions were obtained for bending deflections, flexural vibration frequencies, and buck...
Abstract: A bending theory which includes transverse shear deformations is presented for laminated plates. Closed form solutions are obtained for bending deflections, flexural vibration frequencies, and buck...
443 citations
442 citations
TL;DR: Simultaneous hydrolytic decomposition of barium bis isopropoxide and titanium tetrakis tertiary amyloxide was used to produce stoichiometric BaTiO3.
Abstract: Simultaneous hydrolytic decomposition of barium bis isopropoxide and titanium tetrakis tertiary amyloxide was used to produce stoichiometric BaTiO3. The particle size range was 50 to 150 A. The purity was 99.98+%, the major contaminant being silicon from the glass apparatus. The homogeneity and stoichiometry of the powder were demonstrated by electron microscopy and wet chemical analysis. X-ray and infrared analyses indicate that the material, as-prepared and helium-dried at 5O°C, has the titanate crystal structure. The powder sinters at 1300°C to a high density, translucent body with a uniform microstructure. The experiments suggest that the alkoxy-based preparation of oxides may provide a broad base for improving the quality and reproducibility of electrical and structural ceramics.
247 citations
TL;DR: In this article, a micromechanics analysis for the prediction of composite material properties, which are based upon the assumption of various idealized regular filament packings, indicate the significant in...
Abstract: Existing micromechanics analyses for the prediction of composite material properties, which are based upon the assumption of various idealized regular filament packings, indicate the significant in...
122 citations
TL;DR: In this article, simple solutions of the Einstein scalar and Brans-Dicke field equations are exhibited, and the nature of the Killing horizons of some static solutions is discussed.
Abstract: Simple solutions of the Einstein scalar and Brans-Dicke field equations are exhibited, and the nature of the Killing horizons of some static solutions is discussed.
91 citations
TL;DR: In this article, first principles orthogonalized-plane-wave energy-band calculations have been carried out for cubic ZnS, ZnSe, CdS, and CdSe using a nonrelativistic formalism and Slater's free-electron exchange approximation.
Abstract: First-principles orthogonalized-plane-wave energy-band calculations have been carried out for cubic ZnS, ZnSe, CdS, and CdSe, using a nonrelativistic formalism and Slater's free-electron exchange approximation. The calculations were first carried out in terms of a physically realistic trial crystal potential, and then iterated to obtain a self-consistent solution. So far as we are aware, these are the first fully convergent, fully self-consistent energy-band solutions reported for cubic II-VI semiconducting compounds. In spite of the simplified treatment of exchange effects, and the neglect of relativistic and correlation effects, the first-principles solutions are in qualitative and semi-quantitative agreement with experiment in all cases. It is shown briefly how improved solutions can be obtained by introducing small, carefully chosen empirical corrections. The adequacy of various energy-band models was tested by calculating the optical spectrum (actually ${\ensuremath{\epsilon}}_{2}$) and comparing this with the experimental spectrum. Actually, this comparison checks only certain features of these energy-band models. It would be helpful to have additional experimental information so that other features, such as the energy separation between principal and subsidiary conduction-band minima, could also be checked.
82 citations
TL;DR: In this article, the clean Ir (100) surface was obtained by heating in ultra-high vacuum and shows no atomic rearrangement, however after argon ion-bombardment and mild annealing an Ir(100) 5×1 structure was obtained.
81 citations
TL;DR: In this article, thermal degradation of poly(p-phenylene sulfide), a poly(arylene sulfone), and a poly-sulfonate were subjected to thermal degradation in vacuo, at temperatures between 250 and 620°C.
Abstract: Poly(p-phenylene sulfide), a poly(arylene sulfone), and a poly(arylene sulfonate) were subjected to thermal degradation in vacuo, at temperatures between 250 and 620°C. The volatile and solid degradation products were analyzed by mass spectroscopy, infrared spectroscopy, and elemental analysis. The major decomposition product of poly-(phenylene sulfide) is a condensate, which consists of di- and trimeric chain fragments, dibenzothiophene, and possibly thianthrene. The residual polymer loses two thirds of its sulfur as hydrogen sulfide, however, one third is retained even at 620°C. The most characteristic decomposition reaction of the polysulfone and of the polysulfonate is the almost complete removal of the sulfur as sulfur dioxide. The elimination of sulfur dioxide is practically complete at 450°C for the polysulfone and at 350°C for the polysulfonate.
78 citations
TL;DR: The infrared lattice spectra of a large number of rare-earth garnets have been recorded as discussed by the authors, and a set of three bands in the high-frequency region of each spectrum has been assigned to the motion of the oxygen anions bonded to the rare earth cation.
Abstract: The infrared lattice spectra of a large number of rare-earth garnets have been recorded. Of the seventeen predicted lattice modes, we observed 15 for the aluminum series, 12 for the gallium, and 10 for the iron. A set of three bands in the high-frequency region of each spectrum has been assigned to the motion of the oxygen anions bonded to the rare-earth cation. The lowest-frequency bands in each spectrum have been assigned to the translational motions of the rare-earth ion. All of the frequencies were assigned to external motions of the crystal lattice.
68 citations
TL;DR: In this article, the storage and loss moduli were measured for laminated glass fiber reinforced epoxy composite beams at frequencies up to 9400 Hz, with relatively insensitive storage moduli.
Abstract: Measurements of storage and loss moduli are reported for laminated glass fiber reinforced epoxy composite beams at frequencies up to 9400 Hz. The storage moduli were relatively insensitive and the ...
66 citations
TL;DR: In this article, a state-of-the-art of polymeric ablators is presented, with emphasis on the advantages, limitations, and current problems associated with ablation, including the properties of the polymeric material, thermal-chemical-mechanical aspects of the environment, and the complex interaction of the ablator with its hyperenvironment.
Abstract: Ablative polymers and polymeric composites serve an important function in aerospace technology. They protect aerodynamic surfaces, propulsion structures, and ground equipment from degradative effects of very high temperatures or incident heating rates. This protective function is accomplished by a self-regulating heat and mass transfer process known as ablation. By this relatively new process, thermal energy is expended via sacrificial loss of material. The amount of energy absorbed, dissipated, and blocked depends critically upon both materials and environmental variables. including the properties of the polymeric material, the thermal-chemical-mechanical aspects of the environment, and the complex interaction of the ablator with its hyperenvironment. Important thermochemical and thermo-physical parameters of the ablation process are discussed. In addition, a state-of-the-art of polymeric ablators is presented, with emphasis on the advantages, limitations, and current problems associated with ab...
TL;DR: In this article, the thermoelectric power and electrical conductivity of NbO were measured as functions of temperature at the limiting oxygen activities for the thermodynamic stability of each of the compounds.
TL;DR: It is essential that radiologic, histologic, and clinical expressions be considered before a final diagnosis is made and surgical treatment is instigated in the case of chondromatosis.
TL;DR: The thermal degradation of polyphenylenes and poly(phenylene oxides) was studied under vacuum at temperatures between 350 and 620°C as discussed by the authors, and the volatile and solid degradation products were analyzed by mass spectroscopy, infrared spectroscopic, and elemental analysis.
Abstract: The thermal degradation of polyphenylenes and poly(phenylene oxides) was studied under vacuum at temperatures between 350 and 620°C. The volatile and solid degradation products were analyzed by mass spectroscopy, infrared spectroscopy, and elemental analysis. Overall mechanisms for the thermal breakdown have been proposed. Polyphenylene decomposes to form polymer carbon, while hydrogen is the major volatile product. Some ring breakdown occurs with evolution of methane. Poly(phenylene oxide) forms mainly low molecular weight chain fragments, partially with hydroxyl endgroups. Some of the ether linkages decompose with ring breakdown, yielding carbon monoxide, water, and some carbon dioxide. Pendent groups on polyphenylenes and poly(phenylene oxides) are removed at the lower temperatures. The hydroxyl group yields essentially carbon monoxide and dioxide (the carbon being supplied by the rings), the methyl group methane, and the methoxy group methane and some methanol.
TL;DR: Algor i thm 352 is a package of double-precision FORTRAN rout ines which consists of the following p r imary Rout ines : MFCVAL, M A T H, and BESSEL.
TL;DR: Perfluoro-magnesium compounds have been synthesized directly from completely fluorinated aryl compounds ( e.g., hexafluorobenzene, decafluorsiphenyl, octafluornotoluene and octaffluoronaphthalene) through their reaction with ethylmagnesium bromide and certain transition metal halides.
TL;DR: In this article, the infrared spectrum of 3-butenenitrile, CH 2 CH-CH 2 CN in the liquid, gaseous and solid states has been recorded from 4000 to 100 cm −1.
TL;DR: In this article, a general discussion of cylindrical bending in laminated plates displaying bending-extensional coupling is presented, including buckling and flexural vibrations in addition to conventional bending problems.
Abstract: Many rectangular laminated plates having a high length to width ratio can be analyzed as an infinite strip [1]. One-dimensional static bending under transverse load has been discussed to a limited extent in References 2 and 3. This note presents a general discussion of cylindrical bending in laminated plates displaying bending-extensional coupling. The analysis includes buckling and flexural vibrations in addition to conventional bending problems.
TL;DR: The infrared spectra of a large number of carbohydrates, and of several other compounds of biological interest, have been recorded, for the range 2000-250 cm −1, at ∼ 110°K as mentioned in this paper.
TL;DR: It is concluded that HFP does not respond to hypovolemia in a consistent manner, and certain patients with advanced failure demonstrated abnormal responses to induced hypovolesmia, the causes for which are complex.
Abstract: Five young normal subjects (NS) and six middle-aged patients with chronic, low-output, congestive heart failure (HFP) were studied before and after 10 minutes of exposure to hypovolemia induced by negative pressure (30 mm Hg) applied to the lower body. ECG, respirometer, and catheters placed in the subclavian artery and superior vena cava permitted measurements of heart rate (HR), respiration rate, arterial and central venous pressures (CVP), and cardiac output (CO). In the group of NS, systemic vascular resistance (SVR) rose moderately, while CVP fell 4.3 mm Hg; CO, stroke volume (SV), stroke work (SW), and central blood volume (CBV) fell about 20%, whereas blood pressure and HR showed little change. In the group of HFP, control hemodynamic values were generally abnormal. In four patients the response to hypovolemia was similar to that of NS. Two patients with advanced heart failure showed no change or a rise in CO, SV, and SW in the face of a fall in CVP (3.1 and 3.7 mm Hg), no change or a fall in SVR, ...
TL;DR: In this article, a self-consistent orthogonalized-plane-wave energy-band calculation has been carried out for cubic AlP using a nonrelativistic formalism and Slater's free-electron exchange approximation.
Abstract: A first-principles self-consistent orthogonalized-plane-wave energy-band calculation has been carried out for cubic AlP using a nonrelativistic formalism and Slater's free-electron-exchange approximation. These are the first fully convergent, fully self-consistent energy-band solutions reported for AlP. The imaginary part of the dielectric constant, spin-orbit splitting, effective masses at $k=0$, and the x-ray form factors (Fourier transforms of the electron charge density) have been calculated. Since little is known experimentally about AlP, no comprehensive comparison can be made with experimental data.
TL;DR: In this article, Shankland interpolation is applied to interpolation problems found in a periodic lattice, such as averaging the valence electron density over the Brillouin zone and the method of interpolating energy bands.
Abstract: The new interpolation procedure of Shankland is applied to interpolation problems found in a periodic lattice. Two problems, the method of averaging the valence electron density over the Brillouin zone and the method of interpolating energy bands throughout the Brillouin zone from values at symmetry points, are discussed in detail. To illustrate the advantages of this procedure, examples are taken from self-consistent cubic ZnS and ZnSe orthogonalized-plane-wave calculations.
TL;DR: The development of a rapid new method based on the measurement of the 19F nuclear magnetic resonance spectra of trifluoroacetyl or other fluorine containing derivatives of peptides and amino-acids for the analysis of mixtures of peptide and amino -acids is reported.
Abstract: WE report here the development of a rapid new method for the analysis of mixtures of peptides and amino-acids. This technique is based on the measurement of the 19F nuclear magnetic resonance spectra of trifluoroacetyl or other fluorine containing derivatives of peptides and amino-acids. Earlier we reported that fluorine magnetic resonance can be used for the quantitative analysis of mixtures of metals as chelate derivatives of trifluoracetylacetone (unpublished results of R. E. S.). Although the proton resonance spectra of Zr(IV) trifluoracetylacetonate and Hf(IV) trifluoracetylacetonate in chloroform are essentially the same, the fluorine resonance peaks are well separated (0.23 p.p.m.) and easily integrated to provide quantitative analysis of Zr and Hf. It is well known that the fluorine chemical shift is much more sensitive (between one and two orders of magnitude) to small differences in shielding than the proton resonance. Experience with the fluorine magnetic resonance of extremely similar metal chelates1 led us to conclude that the same advantage could be realized in detecting small differences in chemically and structurally similar peptides and amino-acids. Accordingly, the N-trifluoracetyl derivatives of the amino-acids and peptides shown in Table 1 were prepared and the fluorine NMR spectra measured. It is readily seen in Table 2 and Figs. 1 and 2 that the fluorine nuclei reflect small differences in structure, acting as what might be termed sensors, with the resonance peak for each trifluoracetyl group appearing at a characteristic field position.
TL;DR: In this article, a series of experiments were performed at Mm-10 using a delta wing with sharp leading edges swept to 75°, and the results of the results led to a description of the principal features of the flowfield.
Abstract: A series of experiments were performed at Mm — 10 using a delta wing with sharp leading edges swept to 75°. Surface oil-flow measurements and impact pressure data were acquired in the lee-side region. Analysis of the results led to a description of the principal features of the flowfield. Results of the impact pressure survey indicated that, to a good approximation, the flowfield was conical. A theoretical analysis in two dimensions was utilized to calculate the in viscid flow properties.
TL;DR: In this article, the stability of unsymmetric cross-ply rectangular plates under uniform shear was investigated and the effect of coupling was ascertained by comparing coupled solutions to those obtained by neglecting the coupling coefficients in the governing equations.
Abstract: Recently solutions have been obtained [1, 2, 3] for the bending, vibrations, and buckling of laminated plates in which coupling between bending and stretch ing is important. However, buckling results were limited to unsymmetric angle- ply laminates under biaxial compression. Thus, there are no solutions available for the buckling of coupled laminates subjected to shear loading.This paper is concerned with the stability of unsymmetric cross-ply rectangular plates under uniform shear. These composites consist of an even number of layers all of the same thickness and elastic properties with the orthotropic axes of symmetry in each ply alternately oriented at 0° and 90° to the plate axes. Hinge- support boundary conditions are considered. The effect of coupling is ascertained by comparing coupled solutions to those obtained by neglecting the coupling coefficients in the governing equations. Applicability of the reduced bending stiffness approximation to shear buckling of cross-ply composites is also in vestig...
TL;DR: In this paper, the thermal decomposition of three aromatic polyesters was studied in vacuo and the degradation products were analyzed by mass spectroscopy, infrared and elemental analysis, showing that primary cleavage of the ester linkages appears to take place either between the carbonyl and the oxygen or between the oxygen and the ring, yielding carbon monoxide and carbon dioxide in varying ratios.
Abstract: The thermal decomposition of three aromatic polyesters was studied in vacuo. The degradation products were analyzed by mass spectroscopy, infrared spectroscopy, and elemental analysis. Breakdown mechanisms are proposed. Primary cleavage of the ester linkages appears to take place either between the carbonyl and the oxygen or between the oxygen and the ring, yielding carbon monoxide and carbon dioxide in varying ratios. Another major decomposition product is a sublimate which seems to consist mainly of the phenolic component of the polyester. A polyester with a 2,2-propylene linkage showed, as expected, early loss of methane. A pendent pentyloxy chain in one of the polymers is removed almost completely below 350°C with formation of alkanes and alkenes. Lack of oxygen in the fragments indicates that the main cleavage must occur between the ether oxygen and the aliphatic chain or with in the aliphatic chain.
TL;DR: In this article, the lithiation of 1,2,3,4,4-tetrafluorobenzene with n-butyllithium was described.
TL;DR: In this paper, the energy levels of the cubic crystal field of Ca${\mathrm{F}}_{2}$ were calculated using free-ion vectors computed with spin-other-orbit and spin-spin interactions.
Abstract: The energy levels of ${\mathrm{Gd}}^{3+}$ in the cubic crystal field of Ca${\mathrm{F}}_{2}$ are calculated using free-ion vectors computed with spin-other-orbit and spin-spin interactions included The ${{B}_{0}}^{4}$ and ${{B}_{0}}^{6}$ coefficients are fitted to the experimental $^{6}P_{\frac{7}{2}}$ and $^{6}P_{\frac{5}{2}}$ splittings Using only the 18 ${M}_{J}$ components of the $^{6}P$ free-ion levels as a basis, values of ${{B}_{0}}^{4}=\ensuremath{-}227079$ ${\mathrm{cm}}^{\ensuremath{-}1}$ and ${{B}_{0}}^{6}=73065$ ${\mathrm{cm}}^{\ensuremath{-}1}$ are obtained This calculation gives a mean error of 8 ${\mathrm{cm}}^{\ensuremath{-}1}$ between calculated and experimental levels To improve the quality of the fit, the basis was extended to the 134 ${M}_{J}$ components of the $^{8}S$ and $^{6}(P, I, D)$ free-ion levels For this calculation, ${{B}_{0}}^{4}=\ensuremath{-}21600$ ${\mathrm{cm}}^{\ensuremath{-}1}$ and ${{B}_{0}}^{6}=79285$ ${\mathrm{cm}}^{\ensuremath{-}1}$, and the mean error is reduced to about 05 ${\mathrm{cm}}^{\ensuremath{-}1}$ This calculation predicts the correct order of the ground-state levels and gives an over-all ground-state splitting of about one-half the experimental splitting The calculated ground-state splitting does not change when the basis is further extended to include all higher free-ion levels containing $^{6}G$ character We conclude that a good crystal-field calculation for ${\mathrm{Gd}}^{3+}$ is possible and depends strongly on the quality of the free-ion states