8,879 research outputs found
The New Zealand Strong Motion Earthquake Recorder Network
The network of strong-motion earthquake recorders, maintained throughout
New Zealand by the Engineering Seismology Section of the Department of
Scientific and Industrial Research, is described. The instruments are either
deployed as ground instruments to measure potential earthquake attack on
structures, or in structures, e.g. buildings, dams and industrial installations,
to record structural response. Details are given of installation of instruments , maintenance, laboratory work, record retrieval and digitisation,
costs and staffing for the network. Future developments mooted include an
improved digitising system, the introduction of an improved version of the
existing mechanical-optical instrument in 1979, and, in the long term, the
introduction of an entirely new digital recorder, having an electrical
output from its accelerometers, which will make possible the transmission
of data by telephone or radio link
Helical recorder
Tape recorder, using metallic tape, has a minimum of moving parts and no belts. It permits long-term bulk storage in extreme environments, and has less weight and bulk than present recording equipment
Design of an Automated Ultrasonic Scanning System for In-Situ Composite Cure Monitoring and Defect Detection
The preliminary design and development of an automated ultrasonic scanning system for in-situ composite cure monitoring and defect detection in the high temperature environment of an oven was completed. This preliminary design is a stepping stone to deployment in the high temperature and high pressure environment of an autoclave, the primary cure method of aerospace grade thermoset composites. Cure monitoring with real-time defect detection during the process could determine when defects form and how they move. In addition, real-time defect detection during cure could assist validating physics-based process models for predicting defects at all stages of the cure cycle. A physics-based process model for predicting porosity and fiber waviness originating during cure is currently under development by the NASA Advanced Composites Project (ACP). For the design, an ultrasonic contact scanner is enclosed in an insulating box that is placed inside an oven during cure. Throughout the cure cycle, the box is nitrogen-cooled to approximately room temperature to maintain a standard operating environment for the scanner. The composite part is mounted on the outside of the box in a vacuum bag on the build/tool plate. The build plate is attached to the bottom surface of the box. The scanner inspects the composite panel through the build plate, tracking the movement of defects introduced during layup and searching for new defects that may form during cure. The focus of this paper is the evaluation and selection of the build plate material and thickness. The selection was based on the required operating temperature of the scanner, the cure temperature of the composite material, thermal conductivity models of the candidate build plates, and a series of ultrasonic attenuation tests. This analysis led to the determination that a 63.5 mm thick build plate of borosilicate glass would be utilized for the system. The borosilicate glass plate was selected as the build plate material due to the low ultrasonic attenuation it demonstrated, its ability to efficiently insulate the scanner while supporting an elevated temperature on the part side of the plate, and the availability of a 63.5 mm thick plate without the need for lamination
(Mis)perceptions of ethnic group size and consequences for community expectations and cooperation with law enforcement
The changing composition of race and ethnic group size has been noted for Western nations over the last 15 years. Analysis of this change has linked fear of crime and attitudes toward immigrants and prejudice. Changes in ethnic composition are associated with movement of White residents out of traditionally White communities, rising ethnic tension as the ethnic mix shifts, and a heightened sense of injustice regarding the justice system. (Mis)perceptions of ethnic groups size shape attitudes toward minority groups, as well as policy, practice, and individual behavior in the context of the community. This study seeks to understand the extent of such misperceptions in the Australian context and whether misperceptions of race and ethnic composition are associated with beliefs and attitudes toward formal and informal social control. Utilizing Blalock’s racial threat hypothesis, this study analyzes whether perceived relative ethnic group size is associated with self-reported willingness to cooperate with police as a way to minimize perceived threat. Findings suggest that respondents overestimate the size of minority populations while underestimating the majority White composition and that these misperceived distortions in ethnic group size have consequences for informal and formal social control
Athletic pubalgia and associated rehabilitation
BACKGROUND: Evaluation and treatment of groin pain in athletes is challenging. The anatomy is complex, and multiple pathologies often coexist. Different pathologies may cause similar symptoms, and many systems can refer pain to the groin. Many athletes with groin pain have tried prolonged rest and various treatment regimens, and received differing opinions as to the cause of their pain. The rehabilitation specialist is often given a non-specific referral of groin pain or sports hernia. The cause of pain could be as simple as the effects of an adductor strain, or as complex as athletic pubalgia or inguinal disruption. The term sports hernia is starting to be replaced with more specific terms that better describe the injury. Inguinal disruption is used to describe the syndromes related to the injury of the inguinal canal soft tissue environs ultimately causing the pain syndrome. The term athletic pubalgia is used to describe the disruption and/or separation of the more medial common aponeurosis from the pubis, usually with some degree of adductor tendon pathology. TREATMENT: Both non-operative and post-operative treatment options share the goal of returning the athlete back to pain free activity. There is little research available to reference for rehabilitation guidelines and creation of a plan of care. Although each surgeon has their own specific set of post-operative guidelines, some common concepts are consistent among most surgeons. Effective rehabilitation of the high level athlete to pain free return to play requires addressing the differences in the biomechanics of the dysfunction when comparing athletic pubalgia and inguinal disruption. CONCLUSION: Proper evaluation and diagnostic skills for identifying and specifying the difference between athletic pubalgia and inguinal disruption allows for an excellent and efficient rehabilitative plan of care. Progression through the rehabilitative stages whether non-operative or post-operative allows for a focused rehabilitative program. As more information is obtained through MRI imaging and the diagnosis and treatment of inguinal disruption and athletic pubalgia becomes increasingly frequent, more research is warranted in this field to better improve the evidence based practice and rehabilitation of patients. LEVELS OF EVIDENCE: 5
Finding community structure in very large networks
The discovery and analysis of community structure in networks is a topic of
considerable recent interest within the physics community, but most methods
proposed so far are unsuitable for very large networks because of their
computational cost. Here we present a hierarchical agglomeration algorithm for
detecting community structure which is faster than many competing algorithms:
its running time on a network with n vertices and m edges is O(m d log n) where
d is the depth of the dendrogram describing the community structure. Many
real-world networks are sparse and hierarchical, with m ~ n and d ~ log n, in
which case our algorithm runs in essentially linear time, O(n log^2 n). As an
example of the application of this algorithm we use it to analyze a network of
items for sale on the web-site of a large online retailer, items in the network
being linked if they are frequently purchased by the same buyer. The network
has more than 400,000 vertices and 2 million edges. We show that our algorithm
can extract meaningful communities from this network, revealing large-scale
patterns present in the purchasing habits of customers
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Consolidation of Geologic Studies of Geopressured-Geothermal Resources in Texas
Two major structural styles are identified in the Wilcox growth-fault trend of the Texas Gulf Coast. The style in central and southeast Texas is characterized by continuous, closely spaced growth faults that have little associated rollover despite moderate expansion of section and that show little flattening of the fault plane with depth. Where the growth-fault trend crosses the Houston Diapir Province, growth faults are localized by preexisting salt pillows; however, the piercement salt domes formed after the main phase of faulting, so the salt tectonics "overprints" the growth faults. In South Texas (south of Live Oak County), a narrow band of growth faults having high expansion and moderate rollover lies over and downdip of a ridge of deformed, overpressured shale and lies updip of a deep Tertiary-filled basin formed by withdrawal of overpressured shale. Significant antithetic faulting is associated with this band of growth faults. Also in South Texas, the lower Wilcox Lobo trend is deformed by highly listric normal faults beneath an unconformity that is probably related to Laramide tectonic activity. Wilcox sandstone reservoirs are predominantly of high-constructive deltaic (distributary-channel and delta-front) origin. This, together with close spacing of faults and characteristically low permeabilities, limits the size of geopressured reservoirs. The largest reservoirs may be in interfault areas or in salt- or shale-withdrawal basins.Bureau of Economic Geolog
Imaging the Disk around TW Hydrae with the Submillimeter Array
We present ~2"-4" aperture synthesis observations of the circumstellar disk surrounding the nearby young star TW Hya in the CO J = 2-1 and J = 3-2 lines and associated dust continuum obtained with the partially completed Submillimeter Array. The extent and peak flux of the 230 and 345 GHz dust emission follow closely the predictions of the irradiated accretion disk model of Calvet et al. The resolved molecular line emission extends to a radius of at least 200 AU, the full extent of the disk visible in scattered light, and shows a clear pattern of Keplerian rotation. Comparison of the images with two-dimensional Monte Carlo models constrains the disk inclination angle to 7° ± 1°. The CO emission is optically thick in both lines, and the kinetic temperature in the line formation region is ~20 K. Substantial CO depletion, by an order of magnitude or more from canonical dark cloud values, is required to explain the characteristics of the line emission
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