QCD Sum Rule Calculation of Twist-4 Corrections to Bjorken and Ellis-Jaffe Sum Rules

We calculate the twist-4 corrections to the integral of $g_1(x,Q^2)$ in the framework of QCD sum rules using an interpolating nucleon field which contains explicitly a gluonic degree of freedom. This information can be used together with previous calculations of the twist-3 contribution to the second moment of $g_2(x)$ to estimate the higher-twist corrections to the Ellis-Jaffe and Bjorken sum rules. We get $f^{(2)}(proton) = -0.037 \pm 0.006$ and $f^{(2)}(neutron) = -0.013 \pm 0.006$. Numerically our results roughly agree with those obtained by Balitsky, Braun and Kolesnichenko based on a sum rule for a simpler current. Our calculations are far more stable as tested within the sum rule approach but are more sensitive to less well known condensates.Comment: 18pp., 1 figure (uuencoded eps-file), Late

Standardization of Rocket Engine Pulse Time Parameters

Plumes of bipropellant thrusters are a source of contamination. Small bipropellant thrusters are often used for spacecraft attitude control and orbit correction. Such thrusters typically operate in a pulse mode, at various pulse lengths. Quantifying their contamination effects onto spacecraft external surfaces is especially important for long-term complex-geometry vehicles, e.g. International Space Station. Plume contamination tests indicated the presence of liquid phase contaminant in the form of droplets. Their origin is attributed to incomplete combustion. Most of liquid-phase contaminant is generated during the startup and shutdown (unsteady) periods of thruster pulse. These periods are relatively short (typically 10-50 ms), and the amount of contaminant is determined by the thruster design (propellant valve response, combustion chamber size, thruster mass flow rate, film cooling percentage, dribble volume, etc.) and combustion process organization. Steady-state period of pulse is characterized by much lower contamination rates, but may be lengthy enough to significantly conh'ibute to the overall contamination effect. Because there was no standard methodology for thruster pulse time division, plume contamination tests were conducted at various pulse durations, and their results do not allow quantifying contaminant amounts from each portion of the pulse. At present, the ISS plume contamination model uses an assumption that all thrusters operate in a pulse mode with the pulse length being 100 ms. This assumption may lead to a large difference between the actual amounts of contaminant produced by the thruster and the model predictions. This paper suggests a way to standardize thruster startup and shutdown period definitions, and shows the usefulness of this approach to better quantify thruster plume contamination. Use of the suggested thruster pulse time-division technique will ensure methodological consistency of future thruster plume contamination test programs, and allow accounting for thruster pulse length when modeling plume contamination and erosion effects

RENORMALONS FROM EIGHT LOOP EXPANSION OF THE GLUON CONDENSATE IN LATTICE GAUGE THEORY,

We use a numerical method to obtain the weak coupling perturbative coefficients of local operators with lattice regularization. Such a method allows us to extend the perturbative expansions obtained so far by analytical Feynman diagrams calculations. In SU(3) lattice gauge theory in four dimensions we compute the first eight coefficients of the expectation value of the Wilson loop on the elementary plaquette which is related to the gluon condensate. The computed eight coefficients grow with the order much faster than predicted by the presence of the infrared renormalon associated to the dimension of the gluon condensate. However the renormalon behaviour for large order is quite well reproduced if one considers the expansion coefficients in a new coupling related to the lattice coupling by large perturbative corrections. This is expected since the lattice and continuum Lambda scales differ by almost two orders of magnitude.Comment: 11 pages, LaTe

QCD Sum Rule Calculation of Twist-3 Contributions to Polarized Nucleon Structure Functions

Using the framework of QCD sum rules we predict the twist-3 contribution to the second moment of the polarized nucleon structure function $g_2(x)$. As the relevant local operator depends explicitely on the gluon field, we employ a recently studied interpolating nucleon current which contains three quark field and one gluon field operator. Despite the fact that our calculation is based on the analysis of a completely different correlation function, our estimates are consitent with those of Balitsky, Braun and Kolesnichenko who used a three-quark current.Comment: 16pp. , 2 figures (uuencoded eps-files), LateX. Some misprints corrected, results unchange

Boundary Layer Protuberance Simulations in Channel Nozzle Arc-Jet

Two protuberance designs were modeled in the channel nozzle of the NASA Johnson Space Center Atmospheric Reentry Materials and Structures Facility with the Data-Parallel Line Relaxation computational fluid dynamics code. The heating on the protuberance was compared to nominal baseline heating at a single fixed arc-jet condition in order to obtain heating augmentation factors for flight traceability in the Boundary Layer Transition Flight Experiment on Space Shuttle Orbiter flights STS-119 and STS-128. The arc-jet simulations were performed in conjunction with the actual ground tests performed on the protuberances. The arc-jet simulations included non-uniform inflow conditions based on the current best practices methodology and used variable enthalpy and constant mass flow rate across the throat. Channel walls were modeled as fully catalytic isothermal surfaces, while the test section (consisting of Reaction Cured Glass tiles) was modeled as a partially catalytic radiative equilibrium wall. The results of the protuberance and baseline simulations were compared to the applicable ground test results, and the effects of the protuberance shock on the opposite channel wall were investigated

Experimental investigation of pharmacokinetic properties and the accumulation of zinc when administrated nanoform of zinc hydroxide in a comparative aspect with zinc sulfate

The purpose of a preliminary assessment of the biological effect, a comparative study of nanoparticles using test cultures of bakery yeast, the results of which determined the level of inhibition, which was higher than 90%, compared with the figure for the zinc sulfate and the above 145% more compared to the zinc oxide. Investigation was performed on the pharmacokinetic characteristics of the 40 rabbits-males in comparison with that using zinc sulfate, in an enteral or intravenous administration at three dose levels: 10, 50 and 100 mg/k

Polarized Structure Functions in the Valence Quark and Resonance Regions and the GDH Sum

I present in this paper the neutron spin physics program in Hall A at Jefferson Laboratory using a polarized helium-3 target. The program encompasses several completed experiments, in which, valuable spin observables (spin dependent structure functions) were measured in order to learn about how the nucleon spin arises from the behavior of the constituents. These experiments also offer a ground for testing our understanding of the strong regime of quantum chromodynamics (QCD) the theory of strong interactions through the determination of moments of these structure functions.Comment: 9 pages, 2 Postscript figures, XVth International Conference on Particles and Nuclei (PANIC02), Osaka, Japan, 30 September-4 October 200

Estimation of residual strength of pipeline's elbow with volumetric corrosion defect, which is developing

Pipelines are used as one of the most practical and low cost methods for transmission of different liquid petroleum products and gases. Damage on the pipeline is capable to appear during operation due to the accumulation of fatigue and arising of corrosion. The Aim is estimation the residual strength of pipeline's elbow with volumetric surface defect development of which is modeled in time. Deformed state assessment of damaged elbow of pipelines was held in the framework of computer modeling by using finite-element method (FEM). Corrosion damage modeled explicitly as volumetric defect on the outside of the knee pipeline. Based on the results of the study the assessment of the residual strength of pipeline with increasing surface defects in operation from 10 to 45 years has been obtained. Besides, the areas in which there is localization of maximum equivalent stresses and respectively plastic deformation depending on the size of damage were defined. By obtained results may be noted that after 37 years of operation the pipelines with the corresponding defect on surface cannot withstand the maximum load

Singlet vs Nonsinglet Perturbative Renormalization factors of Staggered Fermion Bilinears

In this paper we present the perturbative computation of the difference between the renormalization factors of flavor singlet ($\sum_f\bar\psi_f\Gamma\psi_f$, $f$: flavor index) and nonsinglet ($\bar\psi_{f_1} \Gamma \psi_{f_2}, f_1 \neq f_2$) bilinear quark operators (where $\Gamma = \mathbb{1},\,\gamma_5,\,\gamma_{\mu},\,\gamma_5\,\gamma_{\mu},\, \gamma_5\,\sigma_{\mu\,\nu}$) on the lattice. The computation is performed to two loops and to lowest order in the lattice spacing, using Symanzik improved gluons and staggered fermions with twice stout-smeared links. The stout smearing procedure is also applied to the definition of bilinear operators. A significant part of this work is the development of a method for treating some new peculiar divergent integrals stemming from the staggered formalism. Our results can be combined with precise simulation results for the renormalization factors of the nonsinglet operators, in order to obtain an estimate of the renormalization factors for the singlet operators. The results have been published in Physical Review D.Comment: 8 pages, 3 figures, 2 tables, Proceedings of the 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spai