Buckling of conical shell with local imperfections

Small geometric imperfections in thin-walled shell structures can cause large reductions in buckling strength. Most imperfections found in structures are neither axisymmetric nor have the shape of buckling modes but rather occur locally. This report presents the results of a study of the effect of local imperfections on the critical buckling load of a specific axially compressed thin-walled conical shell. The buckling calculations were performed by using a two-dimensional shell analysis program referred to as the STAGS (Structural Analysis of General Shells) computer code, which has no axisymmetry restrictions. Results show that the buckling load found from a bifurcation buckling analysis is highly dependent on the circumferential arc length of the imperfection type studied. As the circumferential arc length of the imperfection is increased, a reduction of up to 50 percent of the critical load of the perfect shell can occur. The buckling load of the cone with an axisymmetric imperfections is nearly equal to the buckling load of imperfections which extended 60 deg or more around the circumference, but would give a highly conservative estimate of the buckling load of a shell with an imperfection of a more local nature

Nonlinear optical thresholding in a 4-Channel OCDMA system via two-photon absorption

We demonstrate the use of a Two-Photon Absorption based detector in an OCDMA system. This detector provides a significant performance improvement over standard linear detection

Radiative Models of Sagittarius A* and M87 from Relativistic MHD Simulations

Ongoing millimeter VLBI observations with the Event Horizon Telescope allow unprecedented study of the innermost portion of black hole accretion flows. Interpreting the observations requires relativistic, time-dependent physical modeling. We discuss the comparison of radiative transfer calculations from general relativistic MHD simulations of Sagittarius A* and M87 with current and future mm-VLBI observations. This comparison allows estimates of the viewing geometry and physical conditions of the Sgr A* accretion flow. The viewing geometry for M87 is already constrained from observations of its large-scale jet, but, unlike Sgr A*, there is no consensus for its millimeter emission geometry or electron population. Despite this uncertainty, as long as the emission region is compact, robust predictions for the size of its jet launching region can be made. For both sources, the black hole shadow may be detected with future observations including ALMA and/or the LMT, which would constitute the first direct evidence for a black hole event horizon.Comment: 8 pages, 2 figures, submitted to the proceedings of AHAR 2011: The Central Kiloparse

Usage and Function of Social Media among Students in Higher Education Institutions

This study aimed to find out the usage and function of social media among students in higher education institutions in Tuguegarao City, Cagayan, Philippines. The researcher used the mixed methods research design to determine the social media usage and function among students. The study revealed that students in higher education institutions are not yet very much engaged to social media considering their low social media utilization. Interestingly, differentials in social media utilization is explained by religion, senior high school track, department affiliation, and academic strand. Higher social media utilization is observed among Roman Catholic students, non-academic graduates, senior high school track, department affiliation, and those who took the general academic strand. Furthermore, social media utilization is not associated with students’ average family income, age, and year level. It is recommended that parents/guardians should continue monitoring their children/wards in using their social media account to maintain low to medium usage and exposure to electronic gadgets; teachers should allow their students utilize their social media account as it greatly helps them in performing their various academic tasks; and students should maintain their social media utilization under control at a minimal load expense

Information and Media Literacy of K to 12 and Non-K to 12 Graduates

This study aimed to find out the information and media literacy of K to 12 and n0n-K to 12 graduates in Northern Philippines. The researcher used the mixed methods research design to determine the social media usage and function among students. Students in private and public higher education institutions in the Province of Cagayan, Philippines are not yet very much engaged to social media considering their low social media utilization. They too, have not met the standard learning competencies prescribed in the Curriculum Guide for Media and Information Literacy subject. Interestingly, it shows that the information and media literacy of students varies in terms of sex, basic education preparation, senior high school (SHS) track, and department affiliation but not for religion and ethnicity, and academic strand. It is reflected in the data that female students has higher mean percentage than male students. In addition, The study revealed that the parents’ income and age of the respondents have a significant association with their information and media literacy. The younger respondents tend to have higher information and media literacy while students who were enrolled in SEASH has higher information and media literacy than their counterpart, i.e., those who were enrolled in CBEA, CAHS, CTE, SEAIDITE, SABH, and CHM. It is recommended that there is a need to enhance the information and media literacy of SHS and College students, DICT, CHED and DepEd should strengthen their collaboration relative to the nationwide implementation of the free WiFi school zone projects and conduct a regional follow-up research to track the development of students' Information and Media Literacy at the primary, secondary, and tertiary levels

Self-consistent spectra from radiative GRMHD simulations of accretion onto Sgr A*

We present the first spectral energy distributions produced self-consistently by 2.5D general relativistic magneto-hydrodynamical (GRMHD) numerical simulations, where radiative cooling is included in the dynamical calculation. As a case study, we focus on the accretion flow around the supermassive black hole in the Galactic Centre, Sagittarius A* (Sgr A*), which has the best constrained physical parameters. We compare the simulated spectra to the observational data of Sgr A* and explore the parameter space of our model to determine the effect of changing the initial magnetic field configuration, ion to electron temperature ratio T_i/T_e and the target accretion rate. We find the best description of the data for a mass accretion rate of ~ 1e-9 Msun/yr, and rapid spin (0.7 < a_* < 0.9). The submillimeter peak flux seems largely independent of initial conditions, while the higher energies can be very sensitive to the initial magnetic field configuration. Finally, we also discuss flaring features observed in some simulations, that may be due to artifacts of the 2D configuration.Comment: Submitted to MNRAS. 13 pages, 15 figure

Citizens Dickey-Lincoln Project Impact Review Committee Final Summary Report

The proposed multi-purpose hydroelectric power project at Dickey-Lincoln School would be the largest work..public or private..ever under-taken in the State of Maine. Currently, eight or nine major contacts have been authorized in preparation for writing an environmental impact statement which will assess the project\u27s effect on Maine\u27s economy, resources and social life

Bioinformatics and Classical Literary Study

This paper describes the Quantitative Criticism Lab, a collaborative initiative between classicists, quantitative biologists, and computer scientists to apply ideas and methods drawn from the sciences to the study of literature. A core goal of the project is the use of computational biology, natural language processing, and machine learning techniques to investigate authorial style, intertextuality, and related phenomena of literary significance. As a case study in our approach, here we review the use of sequence alignment, a common technique in genomics and computational linguistics, to detect intertextuality in Latin literature. Sequence alignment is distinguished by its ability to find inexact verbal similarities, which makes it ideal for identifying phonetic echoes in large corpora of Latin texts. Although especially suited to Latin, sequence alignment in principle can be extended to many other languages

GRMHD simulations of accretion onto Sgr A*: How important are radiative losses?

We present general relativistic magnetohydrodynamic (GRMHD) numerical simulations of the accretion flow around the supermassive black hole in the Galactic centre, Sagittarius A* (Sgr A*). The simulations include for the first time radiative cooling processes (synchrotron, bremsstrahlung, and inverse Compton) self-consistently in the dynamics, allowing us to test the common simplification of ignoring all cooling losses in the modeling of Sgr A*. We confirm that for Sgr A*, neglecting the cooling losses is a reasonable approximation if the Galactic centre is accreting below ~10^{-8} Msun/yr i.e. Mdot < 10^{-7} Mdot_Edd. But above this limit, we show that radiative losses should be taken into account as significant differences appear in the dynamics and the resulting spectra when comparing simulations with and without cooling. This limit implies that most nearby low-luminosity active galactic nuclei are in the regime where cooling should be taken into account. We further make a parameter study of axisymmetric gas accretion around the supermassive black hole at the Galactic centre. This approach allows us to investigate the physics of gas accretion in general, while confronting our results with the well studied and observed source, Sgr A*, as a test case. We confirm that the nature of the accretion flow and outflow is strongly dependent on the initial geometry of the magnetic field. For example, we find it difficult, even with very high spins, to generate powerful outflows from discs threaded with multiple, separate poloidal field loops.Comment: Resubmitted to MNRAS, including modifications in response to referee report. 13 pages, 15 figure

An investigation, testing and modifying of gear to harvest oysters and shell : final contract report for the period 1 July, 1973 through 30 June, 1975

During the 1974-75 contract period the hydraulic escalator was modified and tested in the York and Rappahannock Rive r s . The tests showed that the harvester was capable of raising large quantities of oysters from various types of bottoms. Moreover, these oysters were not broken or crushed, were free .of silt or grit , and t he apparatus caused only minima l damage to the bottom . The modification were made from January to April and field testing began in May 1975 in t he York and Rappahannock Rivers on public and leased bottom and on several types of substrate . The device was demonstrated for oyster growers , television companies, the press, representatives of the Virginia Marine Resources Commission, the Maryland Department of Tidewater Fisheries and a representative of the National Marine Fisheries Service. A total of 16 trials or demonstrations were completed which are listed in detail chronologically i n the appendix