Flight IV technical report for experiment 74-37 contained polycrystalline solidification in low-G

Experiments were performed to study the effect of a low-gravity environment on the columnar-to-equiaxed transition (CET) during polycrystalline solidification. Solutions of H2O-30 wt% NH4Cl and H2O-37 wt% NH4Cl were solidified in semicylindrical molds with radial heat extraction. Both solutions were quenched from the same soak temperature (90 C); the respective superheat temperatures were, therefore, approximately 57 and 23 C. The lower superheat resulted in a completely columnar structure, and the higher superheat resulted in a 1/3 columnar - 2/3 equiaxed microstructure; these results were independent of the relationship between heat flow direction and gravity. Grain multiplication mechanisms observed were showering, thermal inversion driven convection cells, and compositionally induced density inversion driven convection cells

STUDI EKSPERIMENTAL PENGARUH PITCH TERHADAP PENINGKATAN PERPINDAHAN PANAS PADA PENUKAR KALOR PIPA KONSENTRIK DENGAN LOUVERED STRIP INSERT SUSUNAN BACKWARD

Studi Eksperimental Pengaruh Pitch terhadap terhadap Peningkatan Perpindahan Panas pada Penukar Kalor Pipa Konsentrik dengan Louvered Strip Insert Susunan Backward Martina Anantyastuti Susanti Jurusan Teknik Mesin Fakultas Teknik Universitas Sebelas Maret Surakarta, Indonesia email : [email protected] Abstrak Penelitian ini dilakukan untuk menguji karakteristik perpindahan panas dan faktor gesekan pada penukar kalor pipa konsentrik dengan penambahan louvered stip insert (LSI) dengan variasi pitch (S) = 40 mm, 50 mm dan 60mm. Seksi uji berupa penukar kalor pipa konsentrik satu laluan dengan pipa dalam dan pipa luar terbuat dari alumunium. Aliran pada pipa dalam dan annulus berlawanan arah dengan fluida kerja air. Fluida kerja di pipa dalam adalah air panas dimana temperatur masukannya dipertahankan pada 60˚C, sedangkan fluida kerja di annulus adalah air dingin dengan temperatur masukannya ±27˚C. LSI dipasang di pipa dalam dari penukar kalor pipa konsentrik. Dalam penelitian ini pengujian dilakukan dengan penambahan LSI dan tanpa louvered strip insert (plain tube) pada pipa dalam. Hasil penelitian menunjukkan bahwa penukar kalor pipa konsentrik dengan penambahan LSI dengan S = 40, 50 dan 60 mm di pipa dalam menghasilkan bilangan Nusselt, faktor gesekan dan rasio koefisien perpindahan panas yang lebih besar daripada plain tube. Penambahan LSI menghasilkan peningkatan perpindahan panas yang lebih baik dibandingkan plain tube. Pada bilangan Reynolds yang sama, penambahan LSI dengan S = 40, 50 dan 60 mm di pipa dalam meningkatkan bilangan Nusselt berturut-turut dalam kisaran 62,9% - 70,0%; 42,5% - 51,3%; dan 23,1% - 31,4% dibandingkan dengan plain tube. Sedangkan penambahan LSI dengan S = 40, 50 dan 60 mm di pipa dalam menghasilkan faktor gesekan berturut-turut 1,86 - 2,44; 1,04 - 1,62; dan 0,58 - 0,84 kali lebih besar dibandingkan faktor gesekan plain tube. Penambahan LSI, S = 40, 50 dan 60 mm di pipa dalam menghasilkan rasio koefisien perpindahan panas berturut-turut dalam kisaran 1,06 - 1,10; 1,06 - 1,08 dan 1,01 - 1,05. Kata kunci : bilangan Nusselt, bilangan Reynolds, faktor gesekan, louvered strip insert, variasi pitch

Remarks on Bootstrap Percolation in Metric Networks

We examine bootstrap percolation in d-dimensional, directed metric graphs in the context of recent measurements of firing dynamics in 2D neuronal cultures. There are two regimes, depending on the graph size N. Large metric graphs are ignited by the occurrence of critical nuclei, which initially occupy an infinitesimal fraction, f_* -> 0, of the graph and then explode throughout a finite fraction. Smaller metric graphs are effectively random in the sense that their ignition requires the initial ignition of a finite, unlocalized fraction of the graph, f_* >0. The crossover between the two regimes is at a size N_* which scales exponentially with the connectivity range \lambda like_* \sim \exp\lambda^d. The neuronal cultures are finite metric graphs of size N \simeq 10^5-10^6, which, for the parameters of the experiment, is effectively random since N<< N_*. This explains the seeming contradiction in the observed finite f_* in these cultures. Finally, we discuss the dynamics of the firing front

Covering All the Basics: Reforms for a More Just Society

On July 3, 2018, the Government of British Columbia announced the creation of an expert committee to “test the feasibility of a basic income in BC and help find ways to make life better for British Columbians.” This is the report of that committee, the Expert Panel on Basic Income. Through this report, we endeavour to present comprehensive, consistent, and evidence-based advice to the B.C. government in response to the tasks set out in the terms of reference. We do this in six parts, which: introduce our task and provide a summary of the report; present a justice-based framework within which we can analyze the alternatives; provide background information used throughout the report ; describe and analyze potential basic income programs; present our vision for the future and a set of recommendations that will move B.C. on the path toward that vision

Packet Forwarding Algorithms in a Line Network

Abstract. We initiate a competitive analysis of packet forwarding poli-cies for maximum and average flow in a line network. We show that the policies Earliest Arrival and Furthest-To-Go are scalable, but not con-stant competitive, for maximum flow. We show that there is no constant competitive algorithm for average flow.

Deposition of tin oxide, iridium and iridium oxide films by metal-organic chemical vapor deposition for electrochemical wastewater treatment

In this research, the specific electrodes were prepared by metal-organic chemical vapor deposition (MOCVD) in a hot-wall CVD reactor with the presence of O2 under reduced pressure. The Ir protective layer was deposited by using (Methylcyclopentadienyl) (1,5-cyclooctadiene) iridium (I), (MeCp)Ir(COD), as precursor. Tetraethyltin (TET) was used as precursor for the deposition of SnO2 active layer. The optimum condition for Ir film deposition was at 300 °C, 125 of O2/(MeCp)Ir(COD) molar ratio and 12 Torr of total pressure. While that of SnO2 active layer was at 380 °C, 1200 of O2/TET molar ratio and 15 Torr of total pressure. The prepared SnO2/Ir/Ti electrodes were tested for anodic oxidation of organic pollutant in a simple three-electrode electrochemical reactor using oxalic acid as model solution. The electrochemical experiments indicate that more than 80% of organic pollutant was removed after 2.1 Ah/L of charge has been applied. The kinetic investigation gives a two-step process for organic pollutant degradation, the kinetic was zero-order and first-order with respect to TOC of model solution for high and low TOC concentrations, respectively

High performance computing and communications grand challenges program

The so-called protein folding problem has numerous aspects, however it is principally concerned with the {ital de novo} prediction of three-dimensional (3D) structure from the protein primary amino acid sequence, and with the kinetics of the protein folding process. Our current project focuses on the 3D structure prediction problem which has proved to be an elusive goal of molecular biology and biochemistry. The number of local energy minima is exponential in the number of amino acids in the protein. All current methods of 3D structure prediction attempt to alleviate this problem by imposing various constraints that effectively limit the volume of conformational space which must be searched. Our Grand Challenge project consists of two elements: (1) a hierarchical methodology for 3D protein structure prediction; and (2) development of a parallel computing environment, the Protein Folding Workbench, for carrying out a variety of protein structure prediction/modeling computations. During the first three years of this project, we are focusing on the use of two proteins selected from the Brookhaven Protein Data Base (PDB) of known structure to provide validation of our prediction algorithms and their software implementation, both serial and parallel. Both proteins, protein L from {ital peptostreptococcus magnus}, and {ital streptococcal} protein G, are known to bind to IgG, and both have an {alpha} {plus} {beta} sandwich conformation. Although both proteins bind to IgG, they do so at different sites on the immunoglobin and it is of considerable biological interest to understand structurally why this is so. 12 refs., 1 fig