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At least 55 records · Page 3Linked to original sources
USGS2021

Point clouds of bridge generated by terrestrial laser scanner and images via Structure from Motion technique: Comparison study

A collection of points representing an object in space is commonly called a point cloud. There are several techniques for collecting point clouds. This research is focused on a comparison study of two approaches: (1) collecting point clouds with a surveying grade terrestrial laser scanner (TLS) and (2) generating point clouds from drone-taken still images by utilizing Structure-from-Motion (SFM) technique. The paper's main objective is to compare the generated point clouds to each other and show the advantages and disadvantages of both techniques for structural health monitoring of bridges. To achieve the goal of the paper, we selected a pedestrian bridge for a comparison study. For simplicity, the study was limited to a single-span bridge. The bridge we studied is a composite steel and reinforced concrete (RC) bridge with a curved deck. A terrestrial laser scanner was used to scan the bridge from several positions, and point clouds were registered based on point-cloud to point-cloud matching. No targets were used during the collection of the point clouds by the laser scanner. In addition, still images of both bridges were taken by a drone. Based on a quantitative comparison of the results, the paper discusses the pros and cons of both approaches.

California↗
USGS2003

The role of multiple stressor causes in declining amphibian populations: A wingspread workshop summary

Numerous studies have documented the decline of amphibian populations over the past decade and no single factor has been the linked to these widespread declines. Determining the causes of declining amphibian populations worldwide has proven difficult because of the variety of anthropogenic and natural suspect agents. A Wingspread workshop, convened by The Society of Environmental Toxicology and Chemistry (SETAC), brought together individuals with expertise in the areas of amphibian biology, ecotoxicology, natural resource management, and environmental policy. This workshop had three objectives: 1) create a network for future discussions on multiple Stressor causes of declines; 2) characterize and prioritize technical issues critical to the analysis of the decline problem; and 3) identify and develop resource management approaches to promote sustainable and healthy amphibian populations. The workshop proceedings will be summarized in a book entitled, "Multiple Stressors and Declining Amphibian Populations: Evaluating Cause and Effect." This paper summarizes the results of the workshop.

Conference Paper↗
USGS2021

S2HM must be real-time or not?

Seismic structural health monitoring (S 2 HM) has advanced significantly in the last three decades. However, currently there is no consensus on the need for real-time processing of data acquired during an earthquake. Numerous applications exist whereby S 2 HM-equipped systems record valuable seismic response data. A delayed use of the seismic data prohibits timely discovery of hidden damages in a structure which, in turn, possibly increases its vulnerability during events to follow – with increased risk to occupants. Such risks are of particular concern when, for example, there are long-distance/long period effects e.g. for tall buildings and long-span bridges that are significantly affected by events that originate at far distances. These phenomena necessitate near real-time monitored data to make timely data-based informed decisions on the health or performance of the affected structure. The paper discusses criteria for functionality and occupiability thresholds in actual applications.

Conference Paper↗
USGS1985

TRENDS IN BOREHOLE GEOPHYSICS FOR MINERAL EXPLORATION: ASSAYING AND REMOTE DETECTION.

Several borehole geophysical techniques have been developed in recent years. Assaying technique development has been concentrated on nuclear methods, with some progress being made on using electrical and magnetic properties for mineral identification. Adaptation of conventional surface geophysical techniques to the borehole for locating near-misses of mineralized zones has led to the development of borehole resistivity, electromagnetic (EM), gravity and magnetic methods to the borehole environment. This paper discusses some of the applications and pitfalls of these new techniques.

Conference Paper↗
USGS2023

Preliminary analysis of a horizontal multifrequency hydroacoustic device designed for surrogate measurements of suspended sediment concentration: The Horizontal Acoustic Sediment Current Profiler

Single frequency active hydroacoustic measurements have been correlated with suspended sediment concentration. In river systems that include widely varying suspended sediment particle sizes, a multi-frequency hydroacoustic approach has increased predictive capabilities. However, the multi-frequency approach requires installation and operation of multiple sensors in a river channel and relies on technology previously designed for measuring water velocity. The Horizontal Acoustic Sediment Current Profiler (HASCP) is a single unit multi-frequency (500, 1,500, and 2,000 mHz) hydroacoustic sensor that was designed to target suspended sediment concentrations. The HASCP was briefly deployed in the Rio Grande at Albuquerque, NM, USGS gage in 2021 and is currently (2022) in operation at the Colorado River near Cameo, CO gage. Results of preliminary testing of the HASCP are presented in this paper.

Conference Paper↗
USGS2006

A preliminary environmental site investigation for a bridge over the Mississippi River at Moline, Illinois

The Illinois State Geological Survey completed a preliminary environmental site assessment along the alignment of Interstate 74 (I-74) and its bridge over the Mississippi River for the Illinois Department of Transportation (IDOT) in 2002. The objective of the study was to determine if any of the parcels proposed for acquisition or on which soil excavation was intended were sufficiently contaminated to require additional investigation by a commercial environmental consultant under contract to IDOT and to identify potential natural hazards that might have an impact on the proposed construction project. VOC were detected at 13 of 37 sites tested for VOC. These sites included an elevator manufacturer, former foundries, former and active machine shops, former and active gasoline stations, and a former automobile dealer. PAH above TACO Tier 1 residential standards were detected on an island in the Mississippi River. PCB was detected at a former foundry and a control box for a railroad. Magnetic anomalies that might indicate the presence of UST were detected in a park that formerly had been the site of a city garage, adjacent to a parking lot that formerly contained an automobile dealer, and at the sites of three former gasoline stations. These studies helped IDOT to save millions of dollars in highway construction projects. This is an abstract of a paper presented in Contaminated Soils, Sediments and Water: Success and Challenges (Massachusetts Fall 2005).

Conference Paper↗
USGS2002

Chemical and biological availability of hydrocarbons in urban harbor sediments

The degradation of saturated and aromatic hydrocarbons was studied in batch slurry experiments conducted with field-aged sediments, highly impacted by hydrocarbon pollution. Experiments focused on examining the effects of desorption limitations to hydrocarbon mineralization and degradation. Degradation of PAH (e.g., naphthalene, fluorene, acenaphthene) and saturated hydrocarbons was examined in field-aged sediments collected from four sites in greater NY Harbor and western Long Island Sound. The sites were Rikers Island in far western Long Island Sound, Williamsburg Bridge in the East River, Shooters Island in the Arthur Kill, and the Kill Van Kull off Bayonne, New Jersey. Patterns of hydrocarbon desorption and degradation in weathered sediments were complicated by the mixed combustion and oil-derived hydrocarbon sources, and differed markedly from patterns seen in sediments following an oil spill. Rates of degradation in experiments with spiked sediments, especially over short timescales, did not appear to be limited by rates of desorption. This is an abstract of a paper presented at the 224th ACS National Meeting (Boston, MA 8/18-22/2002).

Conference Paper↗
USGS2005

Rapid differentiation of refined fuels using negative electrospray ionization/mass spectrometry

Negative electrospray ionization/MS enabled rapid, specific, and selective screening for unique polar components at parts per million concentrations in commercial hydrocarbon products without extensive sample preparation, separation, chromatography, or quantitation. Commercial fuel types were analyzed with this method, including kerosene, jet fuel, white gas, charcoal lighter fluid, on-road and off-road diesel fuels, and various grades and brands of gasolines. The different types of fuels produced unique and relatively simple spectra. These analyses were then applied to hydrocarbon samples from a large, long-term fuel spill. Although the alkane, isoprenoid, and alkylcyclohexane portions began to biodegrade or weather, the polar components in these samples remained relatively unchanged. The type of fuel involved was readily identified by negative electrospray ionization/MS. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005).

Conference Paper↗
USGS1997

Hydrologic inferences from strontium isotopes in pore water from the unsaturated zone at Yucca Mountain, Nevada

Calcite is ubiquitous at Yucca Mountain, occurring in the soils and as fracture and cavity coatings within the volcanic tuff section. Strontium is a trace element in calcite, generally at the tens to hundreds of ppm level. Because calcite contains very little rubidium and the half-life of the 87 Rb parent is billions of years, the 87 Sr/ 86 Sr ratios of the calcite record the ratio in the water from which the calcite precipitated. Dissolution and reprecipitation does not alter these compositions so that, in the absence of other sources of strontium, one would expect the strontium ratios along a flow path to preserve variations inherited from strontium in the soil zone. Strontium isotope compositions of calcites from various settings in the Yucca Mountain region have contributed to the understanding of the unsaturated zone (UZ), especially in distinguishing unsaturated zone calcite from saturated zone calcite. Different populations of calcite have been compared, either to group them together or distinguish them from each other in terms of their strontium isotope compositions. Ground water and perched water have also been analyzed; this paper presents strontium isotope data obtained on pore water.

Nevada↗
USGS2015

Modifications to risk-targeted seismic design maps for subduction and near-fault hazards

ASCE 7-10 introduced new seismic design maps that define risk-targeted ground motions such that buildings designed according to these maps will have 1% chance of collapse in 50 years. These maps were developed by iterative risk calculation, wherein a generic building collapse fragility curve is convolved with the U.S. Geological Survey hazard curve until target risk criteria are met. Recent research shows that this current approach may be unconservative at locations where the tectonic environment is much different than that used to develop the generic fragility curve. This study illustrates how risk-targeted ground motions at selected sites would change if generic building fragility curve and hazard assessment were modified to account for seismic risk from subduction earthquakes and near-fault pulses. The paper also explores the difficulties in implementing these changes.

Conference Paper↗
USGS2004

Characterization of single-walled carbon nanotubes for environmental implications

Adsorption capacities of N2 and various organic vapors (methyl-ethyl ketone (MEK), toluene, and cyclohexane) on select electric-arc and HiPco produced single walled carbon nanotubes (SWNT) were measured at 77 and 298 K, respectively. The amount of N2 adsorbed on a SWNT sample depended on the sample purity, methodology, and on the sample age. Adsorption capacities of organic vapors (100-1000 ppm vol) on SWNT in humid conditions were much higher than those for microporous activated carbons. These results established a foundation for additional studies related to potential environmental applications of SWNT. The MEK adsorption capacities of samples EA95 and CVD80 and mesoporous tire-derived activated carbon in humid conditions were lower than in dry conditions. This is an abstract of a paper presented at the AIChE Annual Meeting (Austin, TX 11/7-12/2004).

Conference Paper↗
USGS2012

Dark and background response stability for the Landsat 8 Thermal Infrared Sensor

The Thermal Infrared Sensor (TIRS) is a pushbroom sensor that will be a part of the Landsat Data Continuity Mission (LDCM), which is a joint mission between NASA and the USGS. The TIRS instrument will continue to collect the thermal infrared data that are currently being collected by the Thematic Mapper and the Enhanced Thematic Mapper Plus on Landsats 5 and 7, respectively. One of the key requirements of the new sensor is that the dark and background response be stable to ensure proper data continuity from the legacy Landsat instruments. Pre launch testing of the instrument has recently been completed at the NASA Goddard Space Flight Center (GSFC), which included calibration collects that mimic those that will be performed on orbit. These collects include images of a cold plate meant to simulate the deep space calibration source as viewed by the instrument in flight. The data from these collects give insight into the stability of the instrument’s dark and background response, as well as factors that may cause these responses to vary. This paper quantifies the measured background and dark response of TIRS as well as its stability.

Conference Paper↗
USGS1984

DEFINITION FOR TALC.

Talc is a naturally occurring single-phase mineral having the approximate chemical formula Mg//3Si//4O//1//0(OH)//2 and a specific type of crystal structure. Talc commonly forms by hydrothermal alteration of rocks rich in magnesium and iron (ultramafic rocks) and by low-grade thermal metamorphism of siliceous dolomites. The fact that talc often occurs in association with other minerals, or that its crystalline form may be platy, fibrous, acicular, or massive, does not modify its definition. The paper discusses variations in talc chemical composition and its crystal structure and describes its characteristic physical properties.

Conference Paper↗
USGS1938

The distribution of botulinus toxin in duck sickness areas

One of the most important events in the history of the diseases of wildfowl wa the discovery of the cause of western duck sickness. Determination that this malady of migratory birds is not a chemical poisoning, as had been previously suspected, was made by Kalmbach and others in 1930-31. Thtat it is a food poisoning resulting from toxins produced by botulinus organisms was proved beyond question. An extensive review of the work leading up to this determination cannot be made in this paper, but some orientation is necessary to a proper appreciation of the subject.

Conference Paper↗
USGS2015

Quality assurance testing of acoustic doppler current profiler transform matrices

The U.S. Geological Survey (USGS) Hydrologic Instrumentation Facility (HIF) is nationally responsible for the design, testing, evaluation, repair, calibration, warehousing, and distribution of hydrologic instrumentation in use within the USGS Water Mission Area (WMA). The HIF's Hydraulic Laboratory has begun routine quality assurance (QA) testing and documenting the performance of every USGS WMA acoustic Doppler current profiler (ADCP) used for making velocity and discharge measurements. All existing ADCPs are being registered and tracked in a database maintained by the HIF, and called for QA checks in the HIF's Hydraulic Laboratory on a 3- year cycle. All new ADCPs purchased directly from the manufacturer as well as ADCPs sent to the HIF or the manufacturer for repair are being registered and tracked in the database and QA checked in the laboratory before being placed into service. Meters failing the QA check are sent directly to the manufacturer for repairs and rechecked by HIF or removed from service. Although this QA program is specific to the SonTek 1 and Teledyne RD Instruments 1 , ADCPs most commonly used within the WMA, it is the intent of the USGS Office of Surface Water and the HIF to expand this program to include all bottom tracking ADCPs as they become available and more widely used throughout the WMA. As part of the HIF QA process, instruments are inspected for physical damage, the instrument must pass the ADCP diagnostic self-check tests, the temperature probe must be within ± 2 degrees Celsius of a National Institute of Standards and Technology traceable reference thermometer and the distance made good over a fixed distance must meet the manufacturer's specifications (+/-0.25% or +/-1% difference). The transform matrix is tested by conducting distance-made-good (DMG) tests comparing the straight-line distance from bottom tracking to the measured tow-track distance. The DMG test is conducted on each instrument twice in the forward and reverse directions (4 tows) at four orientations (16 total tows); with beam 1 orientated 0 degrees to the towing direction; turned 45 degrees to the towing direction; turned 90 degrees to the towing direction; and turned 135 degrees to the towing direction. All QA data files and summary results are archived. This paper documents methodology, participation and preliminary results of WMA ADCP QA testing.

Conference Paper↗
USGS2012

Strong Motion Instrumentation of Seismically-Strengthened Port Structures in California by CSMIP

The California Strong Motion Instrumentation Program (CSMIP) has instrumented five port structures. Instrumentation of two more port structures is underway and another one is in planning. Two of the port structures have been seismically strengthened. The primary goals of the strong motion instrumentation are to obtain strong earthquake shaking data for verifying seismic analysis procedures and strengthening schemes, and for post-earthquake evaluations of port structures. The wharves instrumented by CSMIP were recommended by the Strong Motion Instrumentation Advisory Committee, a committee of the California Seismic Safety Commission. Extensive instrumentation of a wharf is difficult and would be impossible without the cooperation of the owners and the involvement of the design engineers. The instrumentation plan for a wharf is developed through study of the retrofit plans of the wharf, and the strong-motion sensors are installed at locations where specific instrumentation objectives can be achieved and access is possible. Some sensor locations have to be planned during design; otherwise they are not possible to install after construction. This paper summarizes the two seismically-strengthened wharves and discusses the instrumentation schemes and objectives. ?? 2009 ASCE.

Conference Paper↗