13,043 research outputs found

    BACK TO THE BASICS: A NEW CHALLENGE FOR THE BLACK CHURCH

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    The development of the Black community in America witnessed the Black Church exercising the unique function of assisting Blacks to gain a measure of economic strength. The opinion is ventured by Fordham that one of the most powerful and influential institutions to evolve within the Black community in the post-Civil War era was the Black Church. It was more than a religious institution: it was social, political, and economic institution all in one. Its early mutual aid societies cared for the sick, aged, and disabled; buried the dead of indigent families; provided financial support for widows and orphans; made loans; and provided many related community services. In two of his earlier works, DuBois held this same view that the Black Church was more than a religious institution. Defining the major functions of the church within the context of the Black community, he included the roles of setting moral standards, promoting education, working for social uplift of the race, building collective economic power, and providing opportunities for social interaction and recreation

    Introduction

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    In response to the rising tide of racial incidents on college campuses, the National Association for Ethnic Studies has elected to devote this special issue of Explorations in Ethnic Studies to this topic. Hundreds of institutions of all sizes have experienced these ugly and embarrassing incidents

    Critique [of African and Pac!fic Literature: A Comparative Study]

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    Kristine Martin demonstrates the need for the serious scholar to address the topic of African and Pacific literature in the form of comparative analysis. She has provided a good example for others to emulate. for her study is concerned with self-identity in the formation of ethnicity

    Preliminary geologic mapping near the Nilosyrtis Mensae, Mars

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    Virtually the entire map area is mantled by an irregular deposit of material that is apparently fine-grained and erodible. It is also extremely young, as there is not a single crater larger than 1 km in the map area that was emplaced atop the mantle. Knobs abound in the study area; many are presumably caused by the mantling of pre-existing topography. In many cases the older knob of the core is exposed. Many such knob cores are surrounded by small scarplets; it is not yet clear whether the scarplets are the eroded edges of mantle beds that at one time draped over the knob core and have been subsequently exposed by erosion, or whether they are eroded versions of lobate debris aprons. Many craters in the study area contain concentric crater fill, which may indicate downslope movement of volatile-rich materials or repeated cycles of aeolian gradation

    Acousto-ultrasonic input-output characterization of unidirectional fiber composite plate by SH waves

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    A unidirectional fiberglass epoxy composite plate specimen is modelled as a homogeneous transversely isotropic continuum plate medium. Acousto-ultrasonic non-contact input-output characterization by tracing SH waves in the continuum is studied theoretically with a transmitting and receiving transducer located on the same face of the plate. It is found that the directional dependence of the phase velocity of the SH waves travelling in the transversely isotropic medium has a significant effect on the delay time as opposed to the phase velocity of the SH wave travelling in an isotropic medium

    Acousto-ultrasonic input-output characterization of unidirectional fiber composite plate by SV waves

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    A unidirectional fiberglass epoxy compostie specimen is modelled as a homogeneous transversely isotropic continuum plate medium. Acousto-ultrasonic noncontact input-output characterization is studied theoretically with a transmitting and a receiving transducer located on the same face of the plate. The single reflection problem for an incident SV wave at a plane boundary in transversely isotropic medium is analyzed. An obliquely incident SV wave results in a reflected SV wave and a reflected P wave for an angle of incidence of the incident SV wave less than the critical angle. Otherwise, there exists only an SV wave in the medium as the reflected P wave degenerates into a surface wave travelling parallel to the plane boundary. The amplitude ratio of the reflected SV wave is -1 when the angle of incidence is greater than or = the critical angle. The directional dependence of the phase velocity of the SV wave propagating in the transversely isotropic medium has a significant effect on the delay time, as opposed to the directional independence of the phase velocity of a shear wave propagating in an isotropic medium. The displacements associated with the SV wave in the plate and which may be detected by the noncontact receiving transducer are approximated by an asymptotic solution for an infinite transversely isotropic medium subjected to a harmonic point load

    Acousto-ultrasonic input-output characterization of unidirectional fiber composite plate by P waves

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    The single reflection problem for an incident P wave at a stress free plane boundary in a semi-infinite transversely isotropic medium whose isotropic plane is parallel to the plane boundary is analyzed. It is found that an obliquely incident P wave results in a reflected P wave and a reflected SV wave. The delay time for propagation between the transmitting and the receiving transducers is computed as if the P waves were propagating in an infinite half space. The displacements associated with the P waves in the plate and which may be detected by a noncontact NDE receiving transducer are approximated by an asymptotic solution for an infinite transversely isotropic medium subjected to a harmonic point load

    Energy in elastic fiber embedded in elastic matrix containing incident SH wave

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    A single elastic fiber embedded in an infinite elastic matrix is considered. An incident plane SH wave is assumed in the infinite matrix, and an expression is derived for the total energy in the fiber due to the incident SH wave. A nondimensional form of the fiber energy is plotted as a function of the nondimensional wavenumber of the SH wave. It is shown that the fiber energy attains maximum values at specific values of the wavenumber of the incident wave. The results obtained here are interpreted in the context of phenomena observed in acousto-ultrasonic experiments on fiber reinforced composite materials

    Input-output characterization of fiber reinforced composites by P waves

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    Input-output characterization of fiber composites is studied theoretically by tracing P waves in the media. A new path motion to aid in the tracing of P and the reflection generated SV wave paths in the continuum plate is developed. A theoretical output voltage from the receiving transducer is calculated for a tone burst. The study enhances the quantitative and qualitative understanding of the nondestructive evaluation of fiber composites which can be modeled as transversely isotropic media
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