2,226 research outputs found
Resonance testing of space shuttle thermoacoustic structural specimen
The resonance testing of a structural specimen related to the space shuttle vehicle is described. The specimen consisted of a thin aluminum skin reinforced by hat-section stringers and supported by two ribs or bulkheads of corrugated web. A representative section of the space shuttle thermal protection system was bonded to the outer surface of the skin. The tests were completed by using miniature accelerometers to collect vibration data from locations forming a predetermined mesh over the tiles and base structure. The signals were recorded on FM magnetic tape and subsequently analyzed on a modal analysis system
RCA-E/Delta post launch report
The RCA-E spacecraft launch is summarized. Performance of the three stage Delta launch vehicle was nominal and placed the payload in a transfer orbit as planned. The ABM firing is also summarized
The LATDYN user's manual
The LATDYN User's Manual presents the capabilities and instructions for the LATDYN (Large Angle Transient DYNamics) computer program. The LATDYN program is a tool for analyzing the controlled or uncontrolled dynamic transient behavior of interconnected deformable multi-body systems which can undergo large angular motions of each body relative other bodies. The program accommodates large structural deformation as well as large rigid body rotations and is applicable, but not limited to, the following areas: (1) development of large flexible space structures; (2) slewing of large space structure components; (3) mechanisms with rigid or elastic components; and (4) robotic manipulations of beam members. Presently the program is limited to two dimensional problems, but in many cases, three dimensional problems can be exactly or approximately reduced to two dimensions. The program uses convected finite elements to affect the large angular motions involved in the analysis. General geometry is permitted. Detailed user input and output specifications are provided and discussed with example runstreams. To date, LATDYN has been configured for CDC/NOS and DEC VAX/VMS machines. All coding is in ANSII-77 FORTRAN. Detailed instructions regarding interfaces with particular computer operating systems and file structures are provided
Telesat-G/Delta post launch report
The Canadiari Telesat-G (ANIK-D1) commercial communications satellite was launched successfully from the Eastern space and Missile Center (ESMC) at 7:10 p.m., EDT, on August 25, 1982, by a Delta 3920 Vehicle, Mission Number 164. Performance of the two stage Delta launch vehicle was nominal and placed the payload in a low circular orbit as planned. The Payload Assist Module (PAM-D), which is part of the payload, also performed nominally. The synchronous transfer orbital elements achieved by Delta/PAM, compared with the nominal expected, are provided. The satellite performed satisfactorily during the transfer orbit, and the ABM was fired successfully at 5:29 p.m., EDT, on August 29, 1982. The satellite was maneuvered to a position 104 degrees West Longitude above the equator. Satellite status is satisfactory and it has entered service
Comorbid Chronic Pain and Depression: Patient Perspectives on Empathy
Clinician empathy is a well-documented component of effective patient/provider communication. Evidence surrounding the association between patient perspectives on clinician empathy and perception of pain management is currently limited, particularly among patients with chronic pain and depression. The aim of this study was to analyze patientsâ perspectives on the emergent theme of empathy and describe how patients construct their experiences and expectations surrounding empathic interactions. A secondary analysis of focus group data was designed using grounded theory methodology. Veterans Affairs (VA) and University Primary Care Clinics. Respondents with chronic pain and comorbid depression (N = 18) were 27 to 84 years old (mean 54.8 years), 61% women, 22% black, and 74% white. Study participants highly valued empathy and two types of empathic interactions: empathic listening and empathic action. Patients who provided examples of empathic interactions claimed that others understood, valued, and cared for them. In contrast, patients who perceived a lack of empathy and empathic interactions felt frustrated and uncared for by others (including their physicians) physically and emotionally. Patients with chronic pain and depression claimed that empathy helped them feel understood, believed, taken seriously, and that their needs were met. In demonstrating empathy and engaging in empathic interactions with patients, providers relate better to patients, better understand their life experience, and provide patient-centered care that is meaningful for patients, providers, and the health care systems within which they interact. Future research is needed to purposefully study the effects of empathic interactions on outcomes for patients with chronic pain and comorbid depression
Entrainment of randomly coupled oscillator networks by a pacemaker
Entrainment by a pacemaker, representing an element with a higher frequency,
is numerically investigated for several classes of random networks which
consist of identical phase oscillators. We find that the entrainment frequency
window of a network decreases exponentially with its depth, defined as the mean
forward distance of the elements from the pacemaker. Effectively, only shallow
networks can thus exhibit frequency-locking to the pacemaker. The exponential
dependence is also derived analytically as an approximation for large random
asymmetric networks.Comment: 4 pages, 3 figures, revtex 4, submitted to Phys. Rev. Let
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A methodology for the estimation of kappa (Îș) for large datasets. Example application to rock sites in the NGA-East database
This report reviews four of the main approaches (two band-limited and two broadband) currently used for estimating the site Îș0: the acceleration slope (AS) above the corner frequency, the displacement slope (DS) below the corner frequency, the broadband (BB) fit of the spectrum, and the response spectral shape (RESP) template. Using these four methods, estimates of Îș0 for rock sites in Central Eastern North America (CENA) in the shallow crustal dataset from NGAEast are computed for distances less than 100 km.
Using all of the data within 100 km, the mean Îș0 values are 8 msec for the AS approach and 27 msec for the DS approach. These mean values include negative Îș estimates for some sites. If the negative Îș values are removed, then the mean values are 25 msec and 42 msec, respectively. Stacking all spectra together led to mean Îș0 values of 7 and 29 msec, respectively. Overall, the DS approach yields 2â3 times higher values than the AS, which agrees with previous observations, but the uncertainty of the estimates in each case is large. The AS approach seems consistent for magnitudes down to M3 but not below.
There is large within-station variability of Îș that may be related to differences in distance, Q, complexity along the path, or particular source characteristics, such as higher or lower stress drop. The station-to-station differences may be due to site-related factors. Because most sites have been assigned Vs30 = 2000 m/sec, it is not possible to correlate variations in Îș0 with rock stiffness.
Based on the available profile, the individual spectra are corrected for crustal amplification and only affect results below 15 Hz. Since the AS and DS approaches are applied over different frequency ranges, we find that only the DS results are sensitive to the amplification correction. More detailed knowledge of individual near-surface profiles may have effects on AS results, too. Although Îș is considered to be caused solely by damping in the shallow crust, measurement techniques often cannot separate the effects of damping and amplification, and yield the net effect of both phenomena.
The two broadband approaches, BB and RESP, yield similar results. The mean Îș0_BB is 5±0.5 msec across all NEHRP class A sites. The Îș0_RESP for the two events examined is 5 and 6 msec. From literature, the average value of Îș0 in CENA is 6 ± 2 msec. This typical value is similar to the broadband estimates of this study and to the mean ÎșAS when all available recordings are used along with all flags. When only recordings with down-going FAS slope are selected from the dataset, the mean value of ÎșAS increases by a factor of 2â3.
To evaluate the scaling of high-frequency ground motion with Îș, we analyze residuals from ground motion prediction equations (GMPEs) versus Îș estimates. Using the Îș values from the AS approach, the average trend of the ln(PSA) residuals for hard-rock data do not show the expected strong dependence on Îș, but when using Îș values from the DS approach, there is a stronger correlation of the residuals, i.e., a Îș that is more consistent with the commonly used analytically based scaling. The ÎșDS estimates may better reflect the damping in the shallow crust, while the ÎșAS estimates may reflect a net effect of damping and amplification that has not been decoupled. The ÎșDS estimates are higher than the ÎșAS estimates, so the expected effect on the high-frequency ground motion is smaller than that expected for the ÎșAS estimates.
An empirical hard-rock site factor model is developed that represents the combined Vs-Îș0 site factor relative to a 760 m/sec reference-site condition. At low frequencies ( 10 Hz), the residuals do not show the strong increase in the site factors as seen in the analytical model results. A second hard-rock dataset from British Columbia, Canada, is also used. This BC hard-rock residuals show an increase in the 15â50 Hz range that is consistent with the analytical Îș0 scaling for a hard-rock Îș0 of about 0.015 sec.
The variability of the PSA residuals is also used to evaluate the Îș0 scaling for hard-rock sites from analytical modeling. The scatter in existing Îș0 values found in literature is disproportionately large compared to the observed variability in high-frequency ground motions. We compared the predicted ground-motion variability based on analytical modeling to the observed variability in our residuals. While the hard-rock sites are more variable at high frequencies due to the additional Îș0 variability, this additional variability is much less than the variability predicted by the analytical modeling using the variability from Îș0-Vs30 correlations. This is consistent with weaker Îș0 scaling compared to that predicted by the analytical modelling seen in the mean residuals
NYSDOT Living Snow Fence Training
New York State Department of Transportation (NYSDOT) Living Snow Fences Training: challenges, structure, benefits, costs, limitations, economics, transport, effects, development, growth, design, conditions, site assesmen
NYSDOT Living Snow Fence Training Program 2012
New York State Department of Transportation (NYSDOT) Snow Fence Training: plant selection, growth, effects, characteristics, change, site selection, site preparation, existing vegetation, weed control, barriers, root stock, post plant care, limitation
Squeezing Kappa (Îș) out of the transportable array: A strategy for using bandlimited data in regions of sparse seismicity
The Îș parameter (Anderson and Hough, 1984), and namely its site-specific component (Îș0), is important for predicting and simulating high-frequency ground motion. We develop a framework for estimating Îș0 and addressing uncertainties under the challenging conditions often imposed in practice: 1. Low seismicity (limited, poor-quality, distant records); 2. Limited-bandwidth data from the Transportable Array (maximum usable frequency 16 Hz); 3. Low magnitudes (ML1.2-3.4) and large uncertainty in stress drop (corner frequency). We cannot resolve stress drop within the bandwidth, so we propose an approach that only requires upper and lower bounds on its regional values to estimate Îș0. To address uncertainties, we combine three measurement approaches (acceleration spectrum slope, AS; displacement spectrum slope, DS; broadband spectral fit, BB). We also examine the effect of crustal amplification, and find that neglecting it can affect Îș0 by up to 35%. DS estimates greatly exceed AS estimates. We propose a reason behind this bias, related to the residual effect of the corner frequency on ÎșAS and ÎșDS. For our region, we estimate a frequency-independent mean S-wave Q of 900±300 at 9-16 Hz, and an ensemble mean Îș0 over all sites of 0.033±0.014 s. This value is similar to the native Îș0 of the NGA-West2 ground motion prediction equations, indicating that these do not need to be adjusted for Îș0 for use in Southern Arizona. We find that stress drop values in this region may be higher compared to estimates of previous studies, possibly due to trade-offs between stress drop and Îș0. For this dataset, the within-approach uncertainty is much larger than the between-approach uncertainty, and it cannot be reduced if the data quality is not improved. The challenges discussed here will be relevant in studies of Îș for other regions with band-limited data, e.g., any region where data come primarily from the TA
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