6,161 research outputs found
Design considerations for high-power VHF radar transceivers: Phase matching long coaxial cables using a cable radar
The Poker Flat 49.92-MHz MST radar uses 64 phase-controlled transmitters in individual shelters distributed throughout the antenna array. Phase control is accomplished by sampling the transmitted pulse at the directional coupler of each transmitter and sending the sample pulse back to a phase-control unit. This method requires phase matching 64 long (256 meter) coaxial cables (RG-213) to within several electrical degrees. Tests with a time domain reflectometer showed that attenuation of high frequency components in the long RG-213 cable rounded the leading edge of the reflected pulse so that the cables could only be measured to within 50 cm (about 45 deg at 49.92 MHz). Another measurement technique using a vector voltmeter to compare forward and reflected phase required a directional coupler with unattainable directivity. Several other techniques were also found lacking, primarily because of loss in the long RG-213 cables. At this point it was realized that what was needed was a simple version of the phase-coherent clear-air radar, i.e., a cable radar. The design and operation of this cable are described
Design considerations for high-power VHF radar transceivers: The Poker Flat MST radar phase control system
Sixty-four separate 50-kW peak-power transmitters are distributed throughout the 200 x 200 meter Poker Flat MST radar antenna array. The relative phase of each transmitter is automatically controlled by a 64-channel unit located in the main building at the edge of the antenna. The phase control unit is described. In operation the RF pulse from a transmitter coupler is power divided and compared with the phase reference in a mixer. The mixer output is low-pass filtered and sampled near the center of the resulting video pulse by an amplifying sample-and-hold integrated circuit. Phase control is effected by maintaining the mixer output pulse near zero volts by amplifying the sample-and-hold output which then drives the voltage-controlled phase shifter in the direction to null the mixer output. The voltage-controlled shifter achieves over 360 deg phase shift in the range from 0.7 to 24 volts. When the voltage into the shifter tracks to either voltage limit the wrap-around control resets the voltage so that the shifter is always operating within its control range
The ethical implications of the military\u27s product placement and brand integration in popular entertainment
The military relies heavily on advertising. National defense is itself a product that is marketed to the American taxpayer who not only funds the Pentagon but fights its battles. Recruiting is crucial to maintaining the all-volunteer force created in 1973 when the draft was abolished. While plenty of individuals readily sign up others need more encouragement. As of 2014, 1,412,674 people served on active duty in the U.S. military (http://www.bls.gov/ooh/military/military-careers.htm 2014), and while this number may appear impressive it reflects only a tiny part of the population. This paper will examine in depth how the U.S. military uses product placement and product integration in popular entertainment to recruit soldiers. The paper describes the symbiotic relationship between Hollywood and the Pentagon under which the military provides funding and military equipment for military films that encourage young people to volunteer for services and portray the military in a positive light. The paper also examines the ethical issues raised by the use of taxpayer dollars to fund favorable media representations often targeted at audiences far too young to make a rational decision about joining the military. The paper concludes by showing that the military’s propaganda efforts in Hollywood are an important part of the militarization of society that makes foreign military entanglements attractive to the American people
Male engineers: an interpretive phenomenological analysis of the experiences of persistence in higher education
2013 Spring.Includes bibliographical references.More and more engineering programs have become concerned with retention and persistence in their degrees, because about half of their students either change majors or do not graduate at all (Center for Institutional Data Exchange and Analysis, 2000). Male students were chosen for this study because they make up 92.9% of all civil engineers, 90.6% of electrical and electronics engineers, and 90% of all aerospace engineers (National Committee on Pay Equity, 2008). Furthermore, this study was intended to discover factors to better understand how male undergraduate engineering students persisted in their program. While there is a plethora of research on retention and persistence, little qualitative research existed on the male engineering students' perspective of persistence and what factors students identified to assist them to remain in the program. The theoretical framework for this qualitative study was based on the institutional experiences within Tinto's (1993) Student Retention Model. The purpose of this study was to understand factors related to undergraduate engineering students persistence. The five research questions explored were: (1) what factors of the academic experience are helpful to male student persistence in engineering? (2) How does academic performance impact the student experience and their ability to persist in engineering? (3) What factors related to participation in social activities is helpful to male student persistence in engineering? (4) What features of faculty interactions are supportive to male student persistence in engineering? And, (5) what features of peer interactions are supportive to male student persistence in engineering? The research method for this study utilized the interpretative phenomenological analysis. The analysis consisted of twelve total interviews, seven senior and five junior students within the mechanical and electrical and computer departments, at a mid-size private institution, located in the southwest. This study suggested factors that aided in a student's persistence were preparation prior to college, developing a strong support network, and being grounded in academic skills and characteristics. Aspects of intrinsic and extrinsic motivation also assisted these students to persist. These twelve students further expressed their views to why peers left engineering and described certain factors that they felt needed to be tackled to increase persistence in engineering programs
Individuals’ Experiences with Religious Hostility, Discrimination, and Violence: Findings from a New National Survey
While concerns about the consequences of anti-Semitism, Islamophobia, and other forms of religious bias have grown in the past several years, the data available to examine these issues have been limited. This study utilizes new data from a nationally representative survey of U.S. adults featuring oversamples of key religious minority groups and an instrument dedicated to measuring the extent to which individuals experience hostility, discrimination, and violence due to their religion. Findings show that, while a sizable minority of Christian adults report such experiences, a much greater share of Muslim and Jewish adults report experiences with interpersonal hostility, organizational discrimination, and violent victimization due to their religion. Analyses show that these patterns are largely unchanged after accounting for individuals’ race and ethnicity, national origin, and other characteristics, suggesting that experiences with religious hostility are not epiphenomenal to other social locations
Parameters for a Super-Flavor-Factory
A Super Flavor Factory, an asymmetric energy e+e- collider with a luminosity
of order 10^36 cm-2s-1, can provide a sensitive probe of new physics in the
flavor sector of the Standard Model. The success of the PEP-II and KEKB
asymmetric colliders in producing unprecedented luminosity above 10^34 cm-2s-1
has taught us about the accelerator physics of asymmetric e+e- colliders in a
new parameter regime. Furthermore, the success of the SLAC Linear Collider and
the subsequent work on the International Linear Collider allow a new
Super-Flavor collider to also incorporate linear collider techniques. This note
describes the parameters of an asymmetric Flavor-Factory collider at a
luminosity of order 10^36 cm-2s-1 at the Upsilon(4S) resonance and about 10^35
cm-2s-1 at the Tau production threshold. Such a collider would produce an
integrated luminosity of about 10,000 fb-1 (10 ab-1) in a running year (10^7
sec) at the Upsilon(4S) resonance.Comment: Flavor Physics & CP Violation Conference, Vancouver, 200
Can Religiosity Be Explained by ‘Brain Wiring’? An Analysis of US Adults’ Opinions
Studies examining how religion shapes individuals’ attitudes about science have focused heavily on a narrow range of topics, such as evolution. This study expands this literature by looking at how religion influences individuals’ attitudes towards the claim that neuroscience, or “brain wiring,” can explain differences in religiosity. Our analysis of nationally representative survey data shows, perhaps unsurprisingly, that religiosity is negatively associated with thinking that brain wiring can explain religion. Net of religiosity, though, individuals reporting religious experiences are actually more likely to agree that brain wiring can explain religiosity, as are individuals belonging to diverse religious traditions when compared to the unaffiliated. We also find that belief in the general explanatory power of science is a significant predictor of thinking that religiosity can be explained by brain wiring, while women and the more highly educated are less likely to think this is true. Taken together, these findings have implications for our understanding of the relationship between religion and science, and the extent to which neuroscientific explanations of religiosity are embraced by the general US public
Pion photoproduction on the nucleon in the quark model
We present a detailed quark-model study of pion photoproduction within the
effective Lagrangian approach. Cross sections and single-polarization
observables are investigated for the four charge channels, , , , and .
Leaving the coupling strength to be a free parameter, we obtain a
reasonably consistent description of these four channels from threshold to the
first resonance region. Within this effective Lagrangian approach, strongly
constrainted by the quark model, we consider the issue of double-counting which
may occur if additional {\it t}-channel contributions are included.Comment: Revtex, 35 pages, 16 eps figures; version to appear on PR
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