Casting propellant in rocket engine

A method is described for casting a solid propellant in the casing of a rocket engine having a continuous wall with a single opening which is formed by leaves of a material which melt at a temperature of the propellant and with curved edges concentric to the curvature of the spherical casing. The leaves are inserted into the spherical casing through the opening forming a core having a greater width than the width of the single opening and with curved peripheral edges. The cast propellant forms a solid mass and then heated to melt the leaves and provide a central opening with radial projecting flutes

The hydrolysis of proteins

Temperature effects on hydrolysis reaction in protein amino acid

The Coming Boom in Computer Loads

Computers and other electronic equipment now consume as much electricity as electric steel furnaces, and their growth shows no signs of slowing. Utilities are active participants in the computer revolution. Northeast Utilities, for example, reports that 20% of electricity use in a typical new office building in its service area goes to computers. Given the expected growth in computers and computer loads, this technology deserves greater attention from utility planners and other energy analysts. It is shown that the commercial sector has been the largest contributor to kilowatt-hour (kwh) sales growth and that new uses within the commercial sector have accounted for the biggest portion of this growth. Confirming this conclusion are a 4-year Department of Energy-funded study of the Park Plaza Building office tower and a 1985 study of 181 office buildings by Northwest Utilities. A prospective study suggests that computers could account for as much as 150 billion kwh by the early 1990s

Gas-liquid chromatography of amino acids in biological substances

Developing gas-liquid chromatographic method for quantitative analysis of amino acids in blood plasma and urin

Using the local gyrokinetic code, GS2, to investigate global ITG modes in tokamaks. (I) s-α{\alpha} model with profile and flow shear effects

This paper combines results from a local gyrokinetic code with analytical theory to reconstruct the global eigenmode structure of the linearly unstable ion-temperature-gradient (ITG) mode with adiabatic electrons. The simulations presented here employ the s-${\alpha}$ tokamak equilibrium model. Local gyrokinetic calculations, using GS2 have been performed over a range of radial surfaces, x, and for ballooning phase angle, p, in the range -${\pi} {\leq} p {\leq\pi}$, to map out the complex local mode frequency, ${\Omega_0(x, p) = \omega_0(x, p) + i\gamma_0(x, p)}$. Assuming a quadratic radial profile for the drive, namely ${\eta_i = L_n/L_T}$, (holding constant all other equilibrium profiles such as safety factor, magnetic shear etc.), ${\Omega_0(x, p)}$ has a stationary point. The reconstructed global mode then sits on the outboard mid plane of the tokamak plasma, and is known as a conventional or isolated mode, with global growth rate, ${\gamma}$ ~ Max[${\gamma_0(x, p)}$], where ${\gamma_0(x, p)}$ is the local growth rate. Taking the radial variation in other equilibrium profiles (e.g safety factor q(x)) into account, removes the stationary point in ${\Omega_0(x, p)}$ and results in a mode that peaks slightly away from the outboard mid-plane with a reduced global growth rate. Finally, the influence of flow shear has also been investigated through a Doppler shift, ${\omega_0 \rightarrow \omega_0 + n\Omega^{\prime}x}$, where n is the toroidal mode number and ${\Omega^{\prime}}$ incorporates the effect of flow shear. The equilibrium profile variation introduces an asymmetry to the growth rate spectrum with respect to the sign of ${\Omega^{\prime}}$, consistent with recent global gyrokinetic calculations.Comment: 10 pages, 8 figures and 1 tabl

Structure of Micro-instabilities in Tokamak Plasmas: Stiff Transport or Plasma Eruptions?

Solutions to a model 2D eigenmode equation describing micro-instabilities in tokamak plasmas are presented that demonstrate a sensitivity of the mode structure and stability to plasma profiles. In narrow regions of parameter space, with special plasma profiles, a maximally unstable mode is found that balloons on the outboard side of the tokamak. This corresponds to the conventional picture of a ballooning mode. However, for most profiles this mode cannot exist and instead a more stable mode is found that balloons closer to the top or bottom of the plasma. Good quantitative agreement with a 1D ballooning analysis is found provided the constraints associated with higher order profile effects, often neglected, are taken into account. A sudden transition from this general mode to the more unstable ballooning mode can occur for a critical flow shear, providing a candidate model for why some experiments observe small plasma eruptions (Edge Localised Modes, or ELMs) in place of large Type I ELMs.Comment: 11 pages, 3 figure

Calculations of Electronic Potential Energy Surfaces

It is ordinarily possible to simplify the treatment of the dynamics of a general polyatomic system by first considering only the electronic motions, for all possible configurations of artificially fixed nuclei. Any particular electronic eigenvalue, as a function of nuclear geometry, then constitutes an effective potential energy surface, which governs the nuclear motion. The calculation of potential energy surfaces for practical systems represents a major quantum mechanical undertaking which in general becomes tractable only within a framework of approximation and semi empiricism. The major part of this thesis describes calculations developed to estimate the lower lying potential surfaces for the reactive system K + NaCl = KCl + Na. A model treatment is developed and discussed in detail. Essentially the problem is reduced to the consideration of the motion of a single electron in the fields of the closed shell ions Na+, K+ and Cl-. There is good evidence that these ions can be treated as classical polarisable charged spheres in their longer range electrostatic Interactions and also that their structures are not seriously modified by the presence of the single valence electron. The electronic eigenfunction is expanded in terms of a basis set of alkali atom valence s and p-orbitals The most difficult problem is the evaluation of certain close range interactions between the electron and the ions and this matter is discussed in detail. The electronic problem is first solved in neglect of the polarisation of the ion cores and this latter effect is afterwards Introduced, resulting in a first order perturbation correction to the energy surfaces. Empirical evidence used consists of values for ionic polarisabilities and radii, together with experimental ionisation potentials. A suitably reduced version of this model is applied to the calculation of potential curves for the diatomic ions Na2+ , K2+ and NaK+ and yields encouragingly close agreement with experimentally observed properties. The results for the complete system are presented and discussed. The reaction exothermicity is slightly overestimated. There is no calculated activation barrier, the reaction appearing to conform to the "early downhill" classification. A potential well indicates that, If the excess energy were removed, a triangular complex molecule could be formed, some 13 Kcal more stable than the product. Finally there appears to be some qualitative evidence that highly energetic collisions of the reactants may lead to electronically excited product atoms, a phenomenon observed experimentally for the reaction Na+ KBr = NaBr + K. The shorter second part of the thesis presents an estimate of the Jahn-Teller effect in rhenium hexafluoride. This effect arises from the coupling between electronic and nuclear motions when two or more potential surfaces have the same energy in a non linear symmetrical configuration. In such cases the degeneracy is relieved by certain vibrational displacements, leading to a distortion in the equilibrium geometry and a complication of the vibrational spectrum. In rhenium hexafluoride it is assumed that this effect arises from a purely electrostatic Interaction between the fluorine atoms and the non-bonding 5d rhenium electron in a degenerate. r8 state arising from strong spin orbit coupling of the t2g configuration. The electrostatic potential of a fluorine atom is taken as that of a fluoride ion less some variable fraction of an electron, depending on bond ionicity, taken from a hybrid orbital directed towards the central rhenium atom. The rhenium 5d orbital is taken of Slater form with variable exponent. The results, which depend essentially on the potential surface gradients in the octahedral configuration are relatively insensitive to physically reasonable choices of these parameters. A large splitting in the V2 band of the Raman spectrum is predicted, in good order of magnitude agreement with experiment. There is a corresponding very small distortion of the molecular geometry calculated, probably in a tetragonal sense

Effect of Interlayers on Mechanical Properties and Interfacial Stress Transfer of 2D Layered Graphene-Polymer Nanocompsites

Graphene, a monolayer of sp2-hybridized carbon atoms arranged in a two-dimensional (2D) lattice, is one of the most important 2D nanomaterials and has attracted tremendous attentions due to its unique geometric characteristics and exceptional mechanical properties. One of the most promising applications of this 2D nanomaterial is in polymer nanocomposites, in which the ultra-stiff, ultra-thin graphene layers function as reinforcement fillers. However, two significant questions remain to be answered: (1) whether the mechanical behaviors of 2D graphene reinforced nanocomposites can be analyzed by the convention composite theory, which is developed primarily for one-dimensional (1D) fiber-type of fillers, and (2) what are the effects of the “interlayers” in those 2D, ultra-thin, layered fillers on mechanical properties of the nanocomposites. Composites with both aligned and random-distributed graphene are analyzed using Tandon-Weng and Halpin-Tsai models. For composites reinforced with multi-layered graphene, the presence of soft “interlayers” needs to be considered. These layered graphene are treated as the “effective” reinforcement fillers and the moduli of such structures can be predicted by the Arridge model. Finally, the efficiency of reinforcement by 2D, layered graphene in polymer matrix is examined by using the finite element method. The accuracy of the finite element method is verified with the conventional Shear-Lag theory on a monolayer graphene. The distributions of interfacial shear strain are computed for composites reinforced with various layered graphene