Noninvasive identification of bladder cancer with sub-surface backscattered light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bigio, I.J.; Mourant, J.R.; Boyer, J.

1994-02-01

A non-invasive diagnostic tool that could identify malignancy in situ and in real time would have a major impact on the detection and treatment of cancer. We have developed and are testing early prototypes of an optical biopsy system (OBS) for detection of cancer and other tissue pathologies. The OBS invokes a unique approach to optical diagnosis of tissue pathologies based on the elastic scattering properties, over a wide range of wavelengths, of the microscopic structure of the tissue. Absorption bands in the tissue also add useful complexity to the spectral data collected. The use of elastic scattering as themore » key to optical tissue diagnostics in the OBS is based on the fact that many tissue pathologies, including a majority of cancer forms, manifest significant architectural changes at the cellular and sub-cellular level. Since the cellular components that cause elastic scattering have dimensions typically on the order of visible to near-IR wavelengths, the elastic (Mie) scattering properties will be strongly wavelength dependent. Thus, morphology and size changes can be expected to cause significant changes in an optical signature that is derived from the wavelength-dependence of elastic scattering as well as absorption. The data acquisition and storage/display time with the OBS instrument is {approximately}1 second. Thus, in addition to the reduced invasiveness of this technique compared with current state-of-the-art methods (surgical biopsy and pathology analysis), the OBS offers the possibility of impressively faster diagnostic assessment. The OBS employs a small fiber-optic probe that is amenable to use with any endoscope, catheter or hypodermic, or to direct surface examination (e.g., as in skin cancer or cervical cancer). We report here specifically on its potential application in the detection of bladder cancer.« less

Distributed Optical Fiber Sensors with Ultrafast Laser Enhanced Rayleigh Backscattering Profiles for Real-Time Monitoring of Solid Oxide Fuel Cell Operations.

PubMed

Yan, Aidong; Huang, Sheng; Li, Shuo; Chen, Rongzhang; Ohodnicki, Paul; Buric, Michael; Lee, Shiwoo; Li, Ming-Jun; Chen, Kevin P

2017-08-24

This paper reports a technique to enhance the magnitude and high-temperature stability of Rayleigh back-scattering signals in silica fibers for distributed sensing applications. With femtosecond laser radiation, more than 40-dB enhancement of Rayleigh backscattering signal was generated in silica fibers using 300-nJ laser pulses at 250 kHz repetition rate. The laser-induced Rayleigh scattering defects were found to be stable from the room temperature to 800 °C in hydrogen gas. The Rayleigh scatter at high temperatures was correlated to the formation and modification of nanogratings in the fiber core. Using optical fibers with enhanced Rayleigh backscattering profiles as distributed temperature sensors, we demonstrated real-time monitoring of solid oxide fuel cell (SOFC) operations with 5-mm spatial resolution at 800 °C. Information gathered by these fiber sensor tools can be used to verify simulation results or operated in a process-control system to improve the operational efficiency and longevity of SOFC-based energy generation systems.

Orienting Ocean Bottom Seismic Sensors from Ship Noise Polarization Analysis

NASA Astrophysics Data System (ADS)

Barruol, Guilhem; Dreo, Richard; Fontaine, Fabrice R.; Scholz, John R.; Sigloch, Karin; Geay, Bruno; Bouillon, Alexandre

2017-04-01

For the RHUM-RUM project (Réunion Hotspot and Upper Mantle - Réunions Unterer Mantel, www.rhum-rum.net), a network of 57 ocean-bottom seismometers (OBS) was installed on the ocean floor around La Réunion Island in the SW Indian Ocean. Part of the network happened to be located beneath a route of heavy ship traffic connecting SE-Asia and the South-Atlantic region. We analysed the ship noise recorded on the OBS and show that it can be used for determining the horizontal orientations of the seismic instruments as they were recording on the ocean floor. The OBS, provided by the German DEPAS and the French INSU OBS national pools, were equipped with wide-band or broad-band three-components seismic and hydro-acoustic sensors. They were deployed in Nov. 2012 by R/V Marion Dufresne and recovered by R/V Meteor one year later. Depending on the configuration, the OBS recorded for 8 to 13 months. By combining the trajectories of passing ships - provided by AIS (Automatic Identification system) GPS data - with our geophysical data recorded on the ocean floor, we show that both hydro-acoustic and seismic spectral analyses exhibit clear signals associated with vessels between 1 and 50 Hz, in the high-frequency range of our instruments. Large cargo vessels are detected several hours before and after their closest point of approach (CPA) and show clear Doppler effects which put quantitative constraints on their distances and speeds. By analysing the continuous noise polarization on the three seismic components, we show that the polarization of the noise emitted by ships passing in the neighbourhood of an ocean-bottom seismometer can be used for retrieving the orientation of the OBS horizontal components on the ocean floor with respect to the geographic reference frame. We find good agreement between OBS orientations thus calculated from ship noise and the OBS orientations determined independently from teleseismic body and surface wave polarization methods (Scholz et al., GJI, 2017).

Conjugated polymer with carboxylate groups-Hg2 + system as a turn-on fluorescence probe for label-free detection of cysteine-containing compounds

NASA Astrophysics Data System (ADS)

Mi, Hongyu; Guan, Mingming; Liu, Jilin; Shan, Hongyan; Fei, Qiang; Huan, Yanfu; Feng, Guodong

2017-04-01

In this work, a turn on fluorescent sensor, based on Hg2 + coordination conjugated polymer, was developed to detect cysteine-containing compounds. The fluorescence of conjugated polymer (poly(2,5-bis (sodium 4-oxybutyrate) -1,4 - phenylethynylene-alt-1,4-phenyleneethynylene; PPE-OBS) would be quenched by Hg2 + because of the coordination-induced aggregation and electron transfers of PPE-OBS toward Hg2 +. When there were some cysteine-containing compounds in PPE-OBS-Hg2 + system, the fluorescence of PPE-OBS would be recovered. It indicated that the PPE-OBS-Hg2 + system could be used to detect cysteine-containing compounds. Under the optimized conditions, the experiment results showed that there were particularly linear range, high sensitivity and selectivity over other amino acids. The limit of detection (LOD) of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) were 0.725 μmol L- 1, 0.982 μmol L- 1 and 1.21 μmol L- 1 by using this sensor. In addition, Cys standard recovery in several green tea drink and honey samples was also demonstrated. The recovery of Cys was range from 96.3 to 105.0% and RSD was less than 3.25%. The satisfactory results demonstrated that the proposed method could be as a potential fluorescent method for determining cysteine-containing compounds in real samples.

Hyperphagia, lower body temperature, and reduced running wheel activity precede development of morbid obesity in New Zealand obese mice.

PubMed

Jürgens, Hella S; Schürmann, Annette; Kluge, Reinhart; Ortmann, Sylvia; Klaus, Susanne; Joost, Hans-Georg; Tschöp, Matthias H

2006-04-13

Among polygenic mouse models of obesity, the New Zealand obese (NZO) mouse exhibits the most severe phenotype, with fat depots exceeding 40% of total body weight at the age of 6 mo. Here we dissected the components of energy balance including feeding behavior, locomotor activity, energy expenditure, and thermogenesis compared with the related lean New Zealand black (NZB) and obese B6.V-Lep(ob)/J (ob/ob) strains (11% and 65% fat at 23 wk, respectively). NZO mice exhibited a significant hyperphagia that, when food intake was expressed per metabolic body mass, was less pronounced than that of the ob/ob strain. Compared with NZB, NZO mice exhibited increased meal frequency, meal duration, and meal size. Body temperature as determined by telemetry with implanted sensors was reduced in NZO mice, but again to a lesser extent than in the ob/ob strain. In striking contrast to ob/ob mice, NZO mice were able to maintain a constant body temperature during a 20-h cold exposure, thus exhibiting a functioning cold-induced thermogenesis. No significant differences in spontaneous home cage activity were observed among NZO, NZB, and ob/ob strains. When mice had access to voluntary running wheels, however, running activity was significantly lower in NZO than NZB mice and even lower in ob/ob mice. These data indicate that obesity in NZO mice, just as in humans, is due to a combination of hyperphagia, reduced energy expenditure, and insufficient physical activity. Because NZO mice differ strikingly from the ob/ob strain in their resistance to cold stress, we suggest that the molecular defects causing hyperphagia in NZO mice are located distal from leptin and its receptor.

Fiber optic backscatter spectroscopic sensor to monitor enamel demineralization and remineralization in vitro

PubMed Central

Kishen, Anil; Shrestha, Annie; Rafique, Adeela

2008-01-01

In this study, a Fiber Optic Backscatter Spectroscopic Sensor (FOBSS) is used to monitor demineralization and remineralization induced changes in the enamel. A bifurcated fiber optic backscatter probe connected to a visible light source and a high resolution spectrophotometer was used to acquire the backscatter light spectrum from the tooth surface. The experiments were conducted in two parts. In Part 1, experiments were carried out using fiber optic backscatter spectroscopy on (1) sound enamel and dentine sections and (2) sound tooth specimens subjected to demineralization and remineralization. In Part 2, polarization microscopy was conducted to examine the depth of demineralization in tooth specimens. The enamel and dentine specimens from the Part-1 experiments showed distinct backscatter spectra. The spectrum obtained from the enamel-dentine combination and the spectrum generated from the average of the enamel and dentine spectral values were closely similar and showed characteristics of dentine. The experiments in Part 2 showed that demineralization and remineralization processes induced a linear decrease and linear increase in the backscatter light intensity respectively. A negative correlation between the decrease in the backscatter light intensity during demineralization and the depth of demineralization determined using the polarization microscopy was calculated to be p = -0.994. This in vitro experiment highlights the potential benefit of using FOBSS to detect demineralization and remineralization of enamel. PMID:20142887

Recommendations for processing atmospheric attenuated backscatter profiles from Vaisala CL31 ceilometers

NASA Astrophysics Data System (ADS)

Kotthaus, Simone; O'Connor, Ewan; Münkel, Christoph; Charlton-Perez, Cristina; Haeffelin, Martial; Gabey, Andrew M.; Grimmond, C. Sue B.

2016-08-01

Ceilometer lidars are used for cloud base height detection, to probe aerosol layers in the atmosphere (e.g. detection of elevated layers of Saharan dust or volcanic ash), and to examine boundary layer dynamics. Sensor optics and acquisition algorithms can strongly influence the observed attenuated backscatter profiles; therefore, physical interpretation of the profiles requires careful application of corrections. This study addresses the widely deployed Vaisala CL31 ceilometer. Attenuated backscatter profiles are studied to evaluate the impact of both the hardware generation and firmware version. In response to this work and discussion within the CL31/TOPROF user community (TOPROF, European COST Action aiming to harmonise ground-based remote sensing networks across Europe), Vaisala released new firmware (versions 1.72 and 2.03) for the CL31 sensors. These firmware versions are tested against previous versions, showing that several artificial features introduced by the data processing have been removed. Hence, it is recommended to use this recent firmware for analysing attenuated backscatter profiles. To allow for consistent processing of historic data, correction procedures have been developed that account for artefacts detected in data collected with older firmware. Furthermore, a procedure is proposed to determine and account for the instrument-related background signal from electronic and optical components. This is necessary for using attenuated backscatter observations from any CL31 ceilometer. Recommendations are made for the processing of attenuated backscatter observed with Vaisala CL31 sensors, including the estimation of noise which is not provided in the standard CL31 output. After taking these aspects into account, attenuated backscatter profiles from Vaisala CL31 ceilometers are considered capable of providing valuable information for a range of applications including atmospheric boundary layer studies, detection of elevated aerosol layers, and model verification.

Intercomparison of Atmospheric Correction Algorithms Applied to HICO Imagery

DTIC Science & Technology

2011-03-02

photons and shadows a region. The water-leaving radiance from the shadowed region, LwsJu (A) that reaches the sensor results from only skylight ...solar and skylight photons. In addition to the water-leaving radiance, radiance recorded at the sensor also includes path radiance due to molecular (or...one part caused by the backscattering of the diffuse skylight and the other part by backscattering of the direct solar beam. For the sunny and

Probabilistic Verification of Multi-Robot Missions in Uncertain Environments

DTIC Science & Technology

2015-11-01

has been used to measure the environment, including any dynamic obstacles. However, no matter how the model originates, this approach is based on...modeled as bivariate Gaussian distributions and estimated by calibration measurements . The Robot process model is described in prior work [13...sn〉 (pR,pE)(obR) = In〈pR〉〈p〉 ; In〈pE〉〈e〉 ; ( Gtr〈 d(p,e), sr〉〈p1〉 ; Out〈obR,p1〉 | Lte 〈 d(p,e), sr〉〈p2〉 ; Out〈obR, sn+p2 〉 ) ; Sensors

Adaptive focus for deep tissue using diffuse backscatter

NASA Astrophysics Data System (ADS)

Kress, Jeremy; Pourrezaei, Kambiz

2014-02-01

A system integrating high density diffuse optical imaging with adaptive optics using MEMS for deep tissue interaction is presented. In this system, a laser source is scanned over a high density fiber bundle using Digital Micromirror Device (DMD) and channeled to a tissue phantom. Backscatter is then collected from the tissue phantom by a high density fiber array of different fiber type and channeled to CMOS sensor for image acquisition. Intensity focus is directly verified using a second CMOS sensor which measures intensity transmitted though the tissue phantom. A set of training patterns are displayed on the DMD and backscatter is numerically fit to the transmission intensity. After the training patterns are displayed, adaptive focus is performed using only the backscatter and fitting functions. Additionally, tissue reconstruction and prediction of interference focusing by photoacoustic and optical tomographic methods is discussed. Finally, potential NIR applications such as in-vivo adaptive neural photostimulation and cancer targeting are discussed.

European Science Notes Information Bulletin. Reports on Current European and Middle Eastern Science

DTIC Science & Technology

1993-04-01

beamwidth of 2 degrees . Hie had interesting data wideband backscatter in the 2-50 kHz band and on profiles, including hydrothermal plumes ob- forward...civil aviation. Academician P. Naza- gravity in casting Al-Pb alloys. This process renko is rector of the institut’. and Professor N . produces a...pro- east -west sections across 36’ N from Gibraltar to grams such as WOCE (World Ocean Circulation Bermuda and northwest across the Gulf Stream

Microwave Backscatter-Based Wireless Temperature Sensor Fabricated by an Alumina-Backed Au Slot Radiation Patch.

PubMed

Lu, Fei; Wang, Haixing; Guo, Yanjie; Tan, Qiulin; Zhang, Wendong; Xiong, Jijun

2018-01-16

A wireless and passive temperature sensor operating up to 800 °C is proposed. The sensor is based on microwave backscatter RFID (radio frequency identification) technology. A thin-film planar structure and simple working principle make the sensor easy to operate under high temperature. In this paper, the proposed high temperature sensor was designed, fabricated, and characterized. Here the 99% alumina ceramic with a dimension of 40 mm × 40 mm × 1 mm was prepared in micromechanics for fabrication of the sensor substrate. The metallization of the Au slot patch was realized in magnetron sputtering with a slot width of 2 mm and a slot length of 32 mm. The measured resonant frequency of the sensor at 25 °C is 2.31 GHz. It was concluded that the resonant frequency decreases with the increase in the temperature in range of 25-800 °C. It was shown that the average sensor sensitivity is 101.94 kHz/°C.

CO2 lidar backscatter profiles over Hawaii during fall 1988

NASA Technical Reports Server (NTRS)

Post, Madison J.; Cupp, Richard E.

1992-01-01

Aerosol and cloud backscatter data, obtained over a 24-day period in fall 1988 with the National Oceanic and Atmospheric Administration's Doppler lidar at 10.59-micron wavelength, are analyzed by using a new technique to lessen biases that are due to dropouts. Typical backscatter cross sections were significantly lower than those routinely observed over the continental United States, although episodic backscatter enhancements caused by cirrus and mineral dust also occurred. Implications of these data on the proposed Laser Atmospheric Wind Sounder wind profiling satellite sensor are discussed.

OBS development for long term observation in the Marmara Sea, NW Turkey

NASA Astrophysics Data System (ADS)

Takahashi, Narumi; Shimizu, Satoshi; Maekawa, Takuya; Kalafat, Dogan; Pinar, Ali; Citak, Seckin; Kaneda, Yoshiyuki

2015-04-01

We have carried out a collaboration study between Japan and Turkey since 2013, which is one of SATREPS projects, "Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey". The main objective of this project is to reduce risk brought by earthquakes and tsunamis. In particular, the North Anatolian Fault system runs through the Marmara sea and it is expected that the seismic gap exists there according to past seismic studies. The details of seismicity distribution in the Marmara Sea is, however, still insufficient to construct fault model along the active faults. Therefore, we prepare ten ocean bottom seismographs (OBSs) to realize long term observation. We aim to identify size and depth of seismogenic zones using micro seismicity. In addition, we need to cover relative broad area from off-shore Istanbul city to the western end of the Marmara Sea. To clear these conditions, OBS specifications we need are high dynamic range and low instrument noise to observe micro seismicity, low electrical consumption to realize long term observation of over one year, high cost performance to cover the broad area for OBS installation, low cost implementation, and good operability to treat by relatively small number of persons. All items, which are three components velocity sensor, batteries, a recorder, a GPS receiver, a transponder and its transducer to control OBS retrieval, a flasher and a beacon, are installed in the 17 inches glass sphere. The natural frequency of the velocity sensor is 4.5 Hz and the frequency range of our OBS is from 4.5 Hz to 250 Hz. Data sampling is selectable among 100 Hz, 250 Hz and 500 Hz. Because our OBS is deployed by free fall, accuracy of the OBS clock is essentially one of important factors, and it is less than 0.1 ppm. And the resolution of A/D conversion performed on the recorder is 24 bit and we keep the dynamic range of over 135 dB. These data is stored on a semiconductor memory and the capacity is over 300 days with 100 Hz sampling observation. We adopted noncontact charge using lithium ion batteries to reduce implementation cost. And we can charge batteries and transfer stored data without opening glass sphere. All parameters of each OBS are controlled using wireless LAN. In this presentation, we introduce details of OBS development for Japan-Turkey project.

Prediction of Backscatter and Emissivity of Snow at Millimeter Wavelengths.

DTIC Science & Technology

1980-01-01

LIST OF FIGURES Figure Title Page C-I General Area Map 204 C-2 Location of Alpena National Weather 205 Service Station C-3 Photographs of Site E 206 C-4...February 5, 6, 7, 1979 were ob- tained from National Weather Service, Alpena Station and included in Tables C-9 through C-12. Figure C-2 shows the...relative position * 1 of the sites and the Alpena National Weather Service Station. 203 I 0 1 s LAKE HURON ROGERS CITY 20 0 5 10 MILES 0 C HEBOYGAN NORTH

Modeling and characterization of different channels based on human body communication.

PubMed

Jingzhen Li; Zedong Nie; Yuhang Liu; Lei Wang

2017-07-01

Human body communication (HBC), which uses the human body as a transmission medium for electrical signals, provides a prospective communication solution for body sensor networks (BSNs). In this paper, an inhomogeneous model which includes the tissue layers of skin, fat, and muscle is proposed to study the propagation characteristics of different HBC channels. Specifically, the HBC channels, namely, the on-body to on-body (OB-OB)channel, on-body to in-body (OB-IB) channel, in-body to on-body (IB-OB) channel, and in-body to in-body (IB-IB)channel, are studied over different frequencies (from 1MHz to 100MHz) through numerical simulations with finite-difference time-domain (FDTD) method. The results show that the gain of OB-IB channel and IB-OB channel is almost the same. The gain of IB-IB channel is greater than other channels in the frequency range 1MHz to 70MHz. In addition, the gain of all channels is associated with the channel length and communication frequency. The simulations are verified by experimental measurements in a porcine tissue sample. The results show that the simulations are in agreement with the measurements.

Use of sediment rating curves and optical backscatter data to characterize sediment transport in the Upper Yuba River watershed, California, 2001-03

USGS Publications Warehouse

Curtis, Jennifer A.; Flint, Lorraine E.; Alpers, Charles N.; Wright, Scott A.; Snyder, Noah P.

2006-01-01

Sediment transport in the upper Yuba River watershed, California, was evaluated from October 2001 through September 2003. This report presents results of a three-year study by the U.S. Geological Survey, in cooperation with the California Ecosystem Restoration Program of the California Bay-Delta Authority and the California Resources Agency. Streamflow and suspended-sediment concentration (SSC) samples were collected at four gaging stations; however, this report focuses on sediment transport at the Middle Yuba River (11410000) and the South Yuba River (11417500) gaging stations. Seasonal suspended-sediment rating curves were developed using a group-average method and non-linear least-squares regression. Bed-load transport relations were used to develop bed-load rating curves, and bed-load measurements were collected to assess the accuracy of these curves. Annual suspended-sediment loads estimated using seasonal SSC rating curves were compared with previously published annual loads estimated using the Graphical Constituent Loading Analysis System (GCLAS). The percent difference ranged from -85 percent to +54 percent and averaged -7.5 percent. During water year 2003 optical backscatter sensors (OBS) were installed to assess event-based suspended-sediment transport. Event-based suspended-sediment loads calculated using seasonal SSC rating curves were compared with loads calculated using calibrated OBS output. The percent difference ranged from +50 percent to -369 percent and averaged -79 percent. The estimated average annual sediment yield at the Middle Yuba River (11410000) gage (5 tons/mi2) was significantly lower than that estimated at the South Yuba River (11417500) gage (14 tons/mi2). In both rivers, bed load represented 1 percent or less of the total annual load throughout the project period. Suspended sediment at the Middle Yuba River (11410000) and South Yuba River (11417500) gages was typically greater than 85 percent silt and clay during water year 2003, and sand concentrations at the South Yuba River (11417500) gage were typically higher than those at the Middle Yuba River (11410000) gage for a given streamflow throughout the three year project period. Factors contributing to differences in sediment loads and grain-size distributions at the Middle Yuba River (11410000) and South Yuba River (11417500) gages include contributing drainage area, flow diversions, and deposition of bed-material-sized sediment in reservoirs upstream of the Middle Yuba River (11410000) gage. Owing to its larger drainage area, higher flows, and absence of man-made structures that restrict sediment movement in the lower basin, the South Yuba River transports a greater and coarser sediment load.

Velocity and sediment surge: What do we see at times of very shallow water on intertidal mudflats?

NASA Astrophysics Data System (ADS)

Zhang, Qian; Gong, Zheng; Zhang, Changkuan; Townend, Ian; Jin, Chuang; Li, Huan

2016-02-01

A self-designed "bottom boundary layer hydrodynamic and suspended sediment concentration (SSC) measuring system" was built to observe the hydrodynamic and the SSC processes over the intertidal mudflats at the middle part of the Jiangsu coast during August 8-10, 2013. Velocity profiles within 10 cm of the mudflat surface were obtained with a vertical resolution as fine as 1 mm. An ADCP was used to extend the profile over the full water depth with a resolution of 10 cm and the vertical SSC profile was measured at intervals using Optical Backscatter Sensors (OBS). At the same time, water levels and wave conditions were measured with a Tide and Wave Recorder. Measured data suggested that the vertical structure of velocity profiles within 10 cm above the bed maintains a logarithmic distribution during the whole tidal cycle except the slack-water periods. Shallow flows during both the early-flood period and the later-ebb period are characterized by a relatively large vertical velocity gradient and a "surge" feature. We conclude that the very shallow water stages are transient and may not contribute much to the whole water and sediment transport, while they can play a significant role in the formation and evolution of micro-topographies on tidal flats.

Laboratory evaluation of the Sequoia Scientific LISST-ABS acoustic backscatter sediment sensor

USGS Publications Warehouse

Snazelle, Teri T.

2017-12-18

Sequoia Scientific’s LISST-ABS is an acoustic backscatter sensor designed to measure suspended-sediment concentration at a point source. Three LISST-ABS were evaluated at the U.S. Geological Survey (USGS) Hydrologic Instrumentation Facility (HIF). Serial numbers 6010, 6039, and 6058 were assessed for accuracy in solutions with varying particle-size distributions and for the effect of temperature on sensor accuracy. Certified sediment samples composed of different ranges of particle size were purchased from Powder Technology Inc. These sediment samples were 30–80-micron (µm) Arizona Test Dust; less than 22-µm ISO 12103-1, A1 Ultrafine Test Dust; and 149-µm MIL-STD 810E Silica Dust. The sensor was able to accurately measure suspended-sediment concentration when calibrated with sediment of the same particle-size distribution as the measured. Overall testing demonstrated that sensors calibrated with finer sized sediments overdetect sediment concentrations with coarser sized sediments, and sensors calibrated with coarser sized sediments do not detect increases in sediment concentrations from small and fine sediments. These test results are not unexpected for an acoustic-backscatter device and stress the need for using accurate site-specific particle-size distributions during sensor calibration. When calibrated for ultrafine dust with a less than 22-µm particle size (silt) and with the Arizona Test Dust with a 30–80-µm range, the data from sensor 6039 were biased high when fractions of the coarser (149-µm) Silica Dust were added. Data from sensor 6058 showed similar results with an elevated response to coarser material when calibrated with a finer particle-size distribution and a lack of detection when subjected to finer particle-size sediment. Sensor 6010 was also tested for the effect of dissimilar particle size during the calibration and showed little effect. Subsequent testing revealed problems with this sensor, including an inadequate temperature compensation, making this data questionable. The sensor was replaced by Sequoia Scientific with serial number 6039. Results from the extended temperature testing showed proper temperature compensation for sensor 6039, and results from the dissimilar calibration/testing particle-size distribution closely corroborated the results from sensor 6058.

Distributed Fiber-Optic Sensors for Vibration Detection

PubMed Central

Liu, Xin; Jin, Baoquan; Bai, Qing; Wang, Yu; Wang, Dong; Wang, Yuncai

2016-01-01

Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach–Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications. PMID:27472334

Distributed Fiber-Optic Sensors for Vibration Detection.

PubMed

Liu, Xin; Jin, Baoquan; Bai, Qing; Wang, Yu; Wang, Dong; Wang, Yuncai

2016-07-26

Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach-Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications.

Functional imaging of cortical feedback projections to the olfactory bulb

PubMed Central

Rothermel, Markus; Wachowiak, Matt

2014-01-01

Processing of sensory information is substantially shaped by centrifugal, or feedback, projections from higher cortical areas, yet the functional properties of these projections are poorly characterized. Here, we used genetically-encoded calcium sensors (GCaMPs) to functionally image activation of centrifugal projections targeting the olfactory bulb (OB). The OB receives massive centrifugal input from cortical areas but there has been as yet no characterization of their activity in vivo. We focused on projections to the OB from the anterior olfactory nucleus (AON), a major source of cortical feedback to the OB. We expressed GCaMP selectively in AON projection neurons using a mouse line expressing Cre recombinase (Cre) in these neurons and Cre-dependent viral vectors injected into AON, allowing us to image GCaMP fluorescence signals from their axon terminals in the OB. Electrical stimulation of AON evoked large fluorescence signals that could be imaged from the dorsal OB surface in vivo. Surprisingly, odorants also evoked large signals that were transient and coupled to odorant inhalation both in the anesthetized and awake mouse, suggesting that feedback from AON to the OB is rapid and robust across different brain states. The strength of AON feedback signals increased during wakefulness, suggesting a state-dependent modulation of cortical feedback to the OB. Two-photon GCaMP imaging revealed that different odorants activated different subsets of centrifugal AON axons and could elicit both excitation and suppression in different axons, indicating a surprising richness in the representation of odor information by cortical feedback to the OB. Finally, we found that activating neuromodulatory centers such as basal forebrain drove AON inputs to the OB independent of odorant stimulation. Our results point to the AON as a multifunctional cortical area that provides ongoing feedback to the OB and also serves as a descending relay for other neuromodulatory systems. PMID:25071454

Development of compact long-term broadband ocean bottom seismometer for seafloor observation of slow earthquakes

NASA Astrophysics Data System (ADS)

Yamashita, Y.; Shinohara, M.; Yamada, T.; Shiobara, H.

2017-12-01

It is important to understand coupling between plates in a subduction zone for studies of earthquake generation. Recently low frequency tremor and very low frequency earthquake (VLFE) were discovered in plate boundary near a trench. These events (slow earthquakes) in shallow plate boundary should be related to slow slip on a plate boundary. For observation of slow earthquakes, Broad Band Ocean Bottom Seismometer (BBOBS) is useful, however a number of BBOBSs are limited due to cost. On the other hand, a number of Long-term OBSs (LT-OBSs) with recording period of one year are available. However, the LT-OBS has seismometer with a natural period of 1 second. Therefore frequency band of observation is slightly narrow for slow earthquakes. Therefore we developed a compact long-term broad-band OBS by replacement of the seismic sensor of the LT-OBSs to broadband seismometer.We adopted seismic sensor with natural period of 20 seconds (Trillium Compact Broadband Seismometer, Nanometrics). Because tilt of OBS on seafloor can not be controlled due to free-fall, leveling system for seismic sensor is necessary. The broadband seismic senor has cylinder shape with diameter of 90 mm and height of 100 mm, and the developed levelling system can mount the seismic sensor with no modification of shape. The levelling system has diameter of 160 mm and height of 110 mm, which is the same size as existing levelling system of the LT-OBS. The levelling system has two horizontal axes and each axis is driven by motor. Leveling can be performed up to 20 degrees by using micro-processor (Arduino). Resolution of levelling is less than one degree. The system immediately starts leveling by the power-on of controller. After levelling, the the seismic senor is powered and the controller records angles of levelling to SD RAM. Then the controller is shut down to consume no power. Compact long-term broadband ocean bottom seismometer is useful for observation of slow earthquakes on seafloor. In addition, seafloor observations of teleseismic events and deep earthquakes to estimate seismic structure of deep regions and observations of submarine volcanoes are expected.

Correlation studies of passive and active microwave data in the marginal ice zone

NASA Technical Reports Server (NTRS)

Comiso, J. C.

1991-01-01

The microwave radiative and backscatter characteristics of sea ice in an Arctic marginal ice zone have been studied using near-simultaneous passive and active synthetic aperture radar microwave data. Intermediate-resolution multichannel passive microwave data were registered and analyzed. Passive and active microwave data generally complement each other as the two sensors are especially sensitive to different physical properties of the sea ice. In the inner pack, undeformed first-year ice is observed to have low backscatter values but high brightness temperatures while multiyear ice has generally high backscatter values and low brightness temperatures. However, in the marginal ice zone, the signature and backscatter for multiyear ice are considerably different and closer to those of first-year ice. Some floes identified by photography as snow-covered thick ice have backscatter similar to that of new ice or open water while brash ice has backscatter similar to or higher than that of ridged ice.

Towards Snowpack Characterization using C-band Synthetic Aperture Radar (SAR)

NASA Astrophysics Data System (ADS)

Park, J.; Forman, B. A.

2017-12-01

Sentinel 1A and 1B, operated by the European Space Agency (ESA), carries a C-band synthetic aperture radar (SAR) sensor that can be used to monitor terrestrial snow properties. This study explores the relationship between terrestrial snow-covered area, snow depth, and snow water equivalent with Sentinel 1 backscatter observations in order to better characterize snow mass. Ground-based observations collected by the National Oceanic and Atmospheric Administration - Cooperative Remote Sensing Science and Technology Center (NOAA-CREST) in Caribou, Maine in the United States are also used in the comparative analysis. Sentinel 1 Ground Range Detected (GRD) imagery with Interferometric Wide swath (IW) were preprocessed through a series of steps accounting for thermal noise, sensor orbit, radiometric calibration, speckle filtering, and terrain correction using ESA's Sentinel Application Platform (SNAP) software package, which is an open-source module written in Python. Comparisons of dual-polarized backscatter coefficients (i.e., σVV and σVH) with in-situ measurements of snow depth and SWE suggest that cross-polarized backscatter observations exhibit a modest correlation between both snow depth and SWE. In the case of the snow-covered area, a multi-temporal change detection method was used. Results using Sentinel 1 yield similar spatial patterns as when using hyperspectral observations collected by the MODerate Resolution Imaging Spectroradiometer (MODIS). These preliminary results suggest the potential application of Sentinel 1A/1B backscatter coefficients towards improved discrimination of snow cover, snow depth, and SWE. One goal of this research is to eventually merge C-band SAR backscatter observations with other snow information (e.g., passive microwave brightness temperatures) as part of a multi-sensor snow assimilation framework.

Multi-temporal RADARSAT-1 and ERS backscattering signatures of coastal wetlands in southeastern Louisiana

USGS Publications Warehouse

Kwoun, Oh-Ig; Lu, Z.

2009-01-01

Using multi-temporal European Remote-sensing Satellites (ERS-1/-2) and Canadian Radar Satellite (RADARSAT-1) synthetic aperture radar (SAR) data over the Louisiana coastal zone, we characterize seasonal variations of radar backscat-tering according to vegetation type. Our main findings are as follows. First, ERS-1/-2 and RADARSAT-1 require careful radiometric calibration to perform multi-temporal backscattering analysis for wetland mapping. We use SAR backscattering signals from cities for the relative calibration. Second, using seasonally averaged backscattering coefficients from ERS-1/-2 and RADARSAT-1, we can differentiate most forests (bottomland and swamp forests) and marshes (freshwater, intermediate, brackish, and saline marshes) in coastal wetlands. The student t-test results support the usefulness of season-averaged backscatter data for classification. Third, combining SAR backscattering coefficients and an optical-sensor-based normalized difference vegetation index can provide further insight into vegetation type and enhance the separation between forests and marshes. Our study demonstrates that SAR can provide necessary information to characterize coastal wetlands and monitor their changes.

Characterization of Global Near-Nadir Backscatter for Remote Sensing Radar Design

NASA Technical Reports Server (NTRS)

Spencer, Michael W.; Long, David G.

2000-01-01

In order to evaluate side-lobe contamination from the near-nadir region for Ku-Band radars, a statistical characterization of global near-nadir backscatter is constructed. This characterization is performed for a variety of surface types using data from TRMM, Seasat, and Topex. An assessment of the relative calibration accuracy of these sensors is also presented.

Characterization of Global Near-Nadir Backscatter for Remote Sensing Radar Design

NASA Technical Reports Server (NTRS)

Spencer, Michael W.; Long, David G.

2000-01-01

In order to evaluate side-lobe contamination from the near-nadir region for Ku-Band radars, a statistical characterization of global near-nadir backscatter is constructed. This characterization is performed for a variety of surface types using data from TRMM, Seasat, and Topex. An assessment of the relative calibration accuracy of them sensors is also presented.

On-line carbon balance of yeast fermentations using miniaturized optical sensors.

PubMed

Beuermann, Thomas; Egly, Dominik; Geoerg, Daniel; Klug, Kerris Isolde; Storhas, Winfried; Methner, Frank-Juergen

2012-03-01

Monitoring of microbiological processes using optical sensors and spectrometers has gained in importance over the past few years due to its advantage in enabling non-invasive on-line analysis. Near-infrared (NIR) and mid-infrared (MIR) spectrometer set-ups in combination with multivariate calibrations have already been successfully employed for the simultaneous determination of different metabolites in microbiological processes. Photometric sensors, in addition to their low price compared to spectrometer set-ups, have the advantage of being compact and are easy to calibrate and operate. In this work, the detection of ethanol and CO(2) in the exhaust gas during aerobic yeast fermentation was performed by two photometric gas analyzers, and dry yeast biomass was monitored using a fiber optic backscatter set-up. The optical sensors could be easily fitted to the bioreactor and exhibited high robustness during measuring. The ethanol content of the fermentation broth was monitored on-line by measuring the ethanol concentration in the fermentation exhaust and applying a conversion factor. The vapor/liquid equilibrium and the associated conversion factor strongly depend on the process parameter temperature but not on aeration and stirring rate. Dry yeast biomass was determined in-line by a backscattering signal applying a linear calibration. An on-line balance with a recovery rate of 95-97% for carbon was achieved with the use of three optical sensors (two infrared gas analyzers and one fiber optic backscatter set-up). Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Determining suspended sediment particle size information from acoustical and optical backscatter measurements

NASA Astrophysics Data System (ADS)

Lynch, James F.; Irish, James D.; Sherwood, Christopher R.; Agrawal, Yogesh C.

1994-08-01

During the winter of 1990-1991 an Acoustic BackScatter System (ABSS), five Optical Backscatterance Sensors (OBSs) and a Laser In Situ Settling Tube (LISST) were deployed in 90 m of water off the California coast for 3 months as part of the Sediment Transport Events on Shelves and Slopes (STRESS) experiment. By looking at sediment transport events with both optical (OBS) and acoustic (ABSS) sensors, one obtains information about the size of the particles transported as well as their concentration. Specifically, we employ two different methods of estimating "average particle size". First, we use vertical scattering intensity profile slopes (acoustical and optical) to infer average particle size using a Rouse profile model of the boundary layer and a Stokes law fall velocity assumption. Secondly, we use a combination of optics and acoustics to form a multifrequency (two frequency) inverse for the average particle size. These results are compared to independent observations from the LISST instrument, which measures the particle size spectrum in situ using laser diffraction techniques. Rouse profile based inversions for particle size are found to be in good agreement with the LISST results except during periods of transport event initiation, when the Rouse profile is not expected to be valid. The two frequency inverse, which is boundary layer model independent, worked reasonably during all periods, with average particle sizes correlating well with the LISST estimates. In order to further corroborate the particle size inverses from the acoustical and optical instruments, we also examined size spectra obtained from in situ sediment grab samples and water column samples (suspended sediments), as well as laboratory tank experiments using STRESS sediments. Again, good agreement is noted. The laboratory tank experiment also allowed us to study the acoustical and optical scattering law characteristics of the STRESS sediments. It is seen that, for optics, using the cross sectional area of an equivalent sphere is a very good first approximation whereas for acoustics, which is most sensitive in the region ka ˜ 1, the particle volume itself is best sensed. In concluding, we briefly interpret the history of some STRESS transport events in light of the size distribution and other information available. For one of the events "anomalous" suspended particle size distributions are noted, i.e. larger particles are seen suspended before finer ones. Speculative hypotheses for why this signature is observed are presented.

MUG-OBS - Multiparameter Geophysical Ocean Bottom System : a new instrumental approach to monitor earthquakes.

NASA Astrophysics Data System (ADS)

Hello, Y.; Yegikyan, M.; Charvis, P.; Verfaillie, R.; Philippe, O.

2015-12-01

There are several attempts to monitor real time seismic activity, using regional scale wired nodes, such as Neptune in Canada and in the U.S, Antares in France or DONET in Japan.On another hand there are also initiatives in deploying repeatedly OBS array like during the amphibious Cascadia Initiative (four 1-year deployments), the Japanese Pacific Array (broadband OBSs "ocean-bottom broadband dispersion survey" with 2-years autonomy), the Obsismer program in the French Lesser Antilles (eight 6-months deployments) and the Osisec program in Ecuador (four 6-months deployments). These OBSs are autonomous, they are self-recovered or recovered using an ROV. These systems are costly including ship time, and require to recover the OBS before to start working on data.Among the most recent alternative we developed a 3-years autonomy OBS equipped with a Nanometrics Trillium 120 s, a triaxial accelerometer, a differential, an absolute pressure gauge, and a hydrophone. MUG-OBS is a free falling instrument rated down to 6000 m. The installation of the sensor is monitored by acoustic commands from the surface and a health bulletin with data checking is recovered by acoustic during the installation. The major innovation is that it is possible to recover the data any time on demand (regularly every 6-months or after a seismic crisis) utilizing one of the 6 data-shuttles released from the surface by acoustic command using a one day fast cruise boat of opportunity. Since sensors stayed at the same location for 3 years (when an OBS is redeployed on the same site, it will not land in the same place), it is a perfect tool to monitor slow seismic events, background seismic activity and aftershock distribution. Clock, drift measurement and GPS localization is automatic when the shuttle reaches the surface. A new version is being developed; for remote areas, shuttles released automatically and a seismic events bulletin is transmitted. Selected data can be recovered by two- way Iridium satellite communication. After a period of 3 years the main station is ­self-recovered by acoustic.

Rainfall and River Currents Retrieved from Microwave Backscatter

USGS Publications Warehouse

Plant, W.J.; Keller, W.C.; Hayes, K.; Nystuen, J.; Spicer, K.

2003-01-01

The use of CW microwave sensors in yielding information on both river surface velocities and rain rates was discussed. Eight CW microwave sensors were installed at Cowlitz river in Western Washington State in the US. The sensors measured the river surface velocity via Doppler shifts at eight locations across the river. Comparison of the surface velocities derived from the sensors mounted on the bridge with those measured by current meters and acoustic sensors demonstrated good agreement.

Reconstruction of MODIS total suspended matter time series maps by DINEOF and validation with autonomous platform data

NASA Astrophysics Data System (ADS)

Nechad, Bouchra; Alvera-Azcaràte, Aida; Ruddick, Kevin; Greenwood, Naomi

2011-08-01

In situ measurements of total suspended matter (TSM) over the period 2003-2006, collected with two autonomous platforms from the Centre for Environment, Fisheries and Aquatic Sciences (Cefas) measuring the optical backscatter (OBS) in the southern North Sea, are used to assess the accuracy of TSM time series extracted from satellite data. Since there are gaps in the remote sensing (RS) data, due mainly to cloud cover, the Data Interpolating Empirical Orthogonal Functions (DINEOF) is used to fill in the TSM time series and build a continuous daily "recoloured" dataset. The RS datasets consist of TSM maps derived from MODIS imagery using the bio-optical model of Nechad et al. (Rem Sens Environ 114: 854-866, 2010). In this study, the DINEOF time series are compared to the in situ OBS measured in moderately to very turbid waters respectively in West Gabbard and Warp Anchorage, in the southern North Sea. The discrepancies between instantaneous RS, DINEOF-filled RS data and Cefas data are analysed in terms of TSM algorithm uncertainties, space-time variability and DINEOF reconstruction uncertainty.

Remote measurements of water pollution with a lidar polarimeter

NASA Technical Reports Server (NTRS)

Sheives, T. C.; Rouse, J. W., Jr.; Mayo, W. T., Jr.

1974-01-01

This paper examines a dual polarization laser backscatter system as a method for remote measurements of certain water quality parameters. Analytical models for describing the backscatter from turbid water and oil on turbid water are presented and compared with experimental data. Laser backscatter field measurements from natural waterways are presented and compared with simultaneous ground observations of the water quality parameters: turbidity, suspended solids, and transmittance. The results of this study show that the analytical models appear valid and that the sensor investigated is applicable to remote measurements of these water quality parameters and oil spills on water.-

Slot Antenna Integrated Re-Entrant Resonator Based Wireless Pressure Sensor for High-Temperature Applications.

PubMed

Su, Shujing; Lu, Fei; Wu, Guozhu; Wu, Dezhi; Tan, Qiulin; Dong, Helei; Xiong, Jijun

2017-08-25

The highly sensitive pressure sensor presented in this paper aims at wireless passive sensing in a high temperature environment by using microwave backscattering technology. The structure of the re-entrant resonator was analyzed and optimized using theoretical calculation, software simulation, and its equivalent lump circuit model was first modified by us. Micro-machining and high-temperature co-fired ceramic (HTCC) process technologies were applied to fabricate the sensor, solving the common problem of cavity sealing during the air pressure loading test. In addition, to prevent the response signal from being immersed in the strong background clutter of the hermetic metal chamber, which makes its detection difficult, we proposed two key techniques to improve the signal to noise ratio: the suppression of strong background clutter and the detection of the weak backscattered signal of the sensor. The pressure sensor demonstrated in this paper works well for gas pressure loading between 40 and 120 kPa in a temperature range of 24 °C to 800 °C. The experimental results show that the sensor resonant frequency lies at 2.1065 GHz, with a maximum pressure sensitivity of 73.125 kHz/kPa.

Regional Glacier Mapping by Combination of Dense Optical and SAR Satellite Image Time-Series

NASA Astrophysics Data System (ADS)

Winsvold, S. H.; Kääb, A.; Andreassen, L. M.; Nuth, C.; Schellenberger, T.; van Pelt, W.

2016-12-01

Near-future dense time series from both SAR (Sentinel-1A and B) and optical satellite sensors (Landsat 8, Sentinel-2A and B) will promote new multisensory time series applications for glacier mapping. We assess such combinations of optical and SAR data among others by 1) using SAR data to supplement optical time series that suffer from heavy cloud cover (chronological gap-filling), 2) merging the two data types based on stack statistics (Std.dev, Mean, Max. etc.), or 3) better explaining glacier facies patterns in SAR data using optical satellite images. As one example, summer SAR backscatter time series have been largely unexplored and even neglected in many glaciological studies due to the high content of liquid melt water on the ice surface and its intrusion in the upper part of the snow and firn. This water content causes strong specular scattering and absorption of the radar signal, and little energy is scattered back to the SAR sensor. We find in many scenes of a Sentinel-1 time series a significant temporal backscatter difference between the glacier ice surface and the seasonal snow as it melts up glacier. Even though both surfaces have typically wet conditions, we suggest that the backscatter difference is due to different roughness lengths of the two surfaces. Higher backscatter is found on the ice surface in the ablation area compared to the firn/seasonal snow surface. We find and present also other backscatter patterns in the Sentinel-1 time series related to glacier facies and weather events. For the Ny Ålesund area, Svalbard we use Radarsat-2 time series to explore the glacier backscatter conditions in a > 5 year period, discussing distinct temporal signals from among others refreezing of the firn in late autumn, or temporal lakes. All these examples are analyzed using the above 3 methods. By this multi-temporal and multi-sensor approach we also explore and describe the possible connection between combined SAR/optical time series and surface mass balance.

Comparisons of Satellite Soil Moisture, an Energy Balance Model Driven by LST Data and Point Measurements

NASA Astrophysics Data System (ADS)

Laiolo, Paola; Gabellani, Simone; Rudari, Roberto; Boni, Giorgio; Puca, Silvia

2013-04-01

Soil moisture plays a fundamental role in the partitioning of mass and energy fluxes between land surface and atmosphere, thereby influencing climate and weather, and it is important in determining the rainfall-runoff response of catchments; moreover, in hydrological modelling and flood forecasting, a correct definition of moisture conditions is a key factor for accurate predictions. Different sources of information for the estimation of the soil moisture state are currently available: satellite data, point measurements and model predictions. All are affected by intrinsic uncertainty. Among different satellite sensors that can be used for soil moisture estimation three major groups can be distinguished: passive microwave sensors (e.g., SSMI), active sensors (e.g. SAR, Scatterometers), and optical sensors (e.g. Spectroradiometers). The last two families, mainly because of their temporal and spatial resolution seem the most suitable for hydrological applications In this work soil moisture point measurements from 10 sensors in the Italian territory are compared of with the satellite products both from the HSAF project SM-OBS-2, derived from the ASCAT scatterometer, and from ACHAB, an operative energy balance model that assimilate LST data derived from MSG and furnishes daily an evaporative fraction index related to soil moisture content for all the Italian region. Distributed comparison of the ACHAB and SM-OBS-2 on the whole Italian territory are performed too.

In-situ Observations of Swash-zone Flow Velocities and Sediment Transport on a Steep Beach

NASA Astrophysics Data System (ADS)

Chardon-Maldonado, P.; Puleo, J. A.; Figlus, J.

2014-12-01

A 45 m scaffolding frame containing an array of instruments was installed at South Bethany Beach, Delaware, to obtain in-situ measurements in the swash zone. Six cross-shore stations were established to simultaneously measure near-bed velocity profiles, sediment concentration and water level fluctuations on a steep beach. Measurements of swash-zone hydrodynamics and morphological change were collected from February 12 to 25, 2014, following a large Nor'easter storm with surf zone significant wave height exceeding 5 m. Swash-zone flow velocities (u,v,w) were measured at each cross-shore location using a Nortek Vectrino profiling velocimeter that measured a 30 mm velocity profile at 1 mm vertical increments at 100 Hz. These velocity profiles were used to quantify the vertical flow structure over the foreshore and estimate hydrodynamic parameters such as bed shear stress and turbulent kinetic energy dissipation. Sediment concentrations were measured using optical backscatter sensors (OBS) to obtain spatio-temporal measurements during both uprush and backwash phases of the swash cycle. Cross-shore sediment transport rates at each station were estimated by taking the product of cross-shore velocity and sediment concentration. Foreshore elevations were sampled every low tide using a Leica GPS system with RTK capability. Cross-shore sediment transport rates and gradients derived from the velocities and bed shear stress estimates will be related to the observed morphological change.

Experimental assessment of an RFID-based crack sensor for steel structures

NASA Astrophysics Data System (ADS)

E Martínez-Castro, R.; Jang, S.; Nicholas, J.; Bansal, R.

2017-08-01

The use of welded steel cover plates had been a common design practice to increase beam section capacity in regions of high moment for decades. Many steel girder bridges with cover plates are still in service. Steel girder bridges are subject to cyclic loading, which can initiate crack formation at the toe of the weld and reduce beam capacity. Thus, timely detection of fatigue cracks is of utmost importance in steel girder bridge monitoring. To date, crack monitoring methods using in-house radio frequency identification (RFID)-based sensors have been developed to complement visual inspection and provide quantitative information of damage level. Offering similar properties at a reduced cost, commercial ultra-high frequency (UHF) passive RFID tags have been identified as a more financially viable option for pervasive crack monitoring using a dense array of sensors. This paper presents a study on damage sensitivity of low-cost commercial UHF RFID tags for crack detection and monitoring on metallic structures. Using backscatter power as a parameter for damage identification, a crack sensing system has been developed for single and multiple tag configurations for increased sensing pervasiveness. The effect on backscatter power of the existence and stage of crack propagation has been successfully characterized. For further automation of crack detection, a damage index based on the variation of backscatter power has also been established. The tested commercial RFID-based crack sensor contributes to the usage of this technology on steel girder bridges.

Distributed measurement of high electric current by means of polarimetric optical fiber sensor.

PubMed

Palmieri, Luca; Sarchi, Davide; Galtarossa, Andrea

2015-05-04

A novel distributed optical fiber sensor for spatially resolved monitoring of high direct electric current is proposed and analyzed. The sensor exploits Faraday rotation and is based on the polarization analysis of the Rayleigh backscattered light. Preliminary laboratory tests, performed on a section of electric cable for currents up to 2.5 kA, have confirmed the viability of the method.

Aerial ultrasonic micro Doppler sonar detection range in outdoor environments.

PubMed

Bradley, Marshall; Sabatier, James M

2012-03-01

Current research demonstrates that micro Doppler sonar has the capability to uniquely identify the presence of a moving human, making it an attractive component in surveillance systems for border security applications. Primary environmental factors that limit sonar performance are two-way spreading losses, ultrasonic absorption, and backscattered energy from the ground that appears at zero Doppler shift in the sonar signal processor. Spectral leakage from the backscatter component has a significant effect on sonar performance for slow moving targets. Sonar performance is shown to rapidly decay as the sensor is moved closer to the ground due to increasing surface backscatter levels. © 2012 Acoustical Society of America

Intercomparison of Pulsed Lidar Data with Flight Level CW Lidar Data and Modeled Backscatter from Measured Aerosol Microphysics Near Japan and Hawaii

NASA Technical Reports Server (NTRS)

Cutten, D. R.; Spinhirne, J. D.; Menzies, R. T.; Bowdle, D. A.; Srivastava, V.; Pueschel, R. F.; Clarke, A. D.; Rothermel, J.

1998-01-01

Aerosol backscatter coefficient data were examined from two nights near Japan and Hawaii undertaken during NASA's Global Backscatter Experiment (GLOBE) in May-June 1990. During each of these two nights the aircraft traversed different altitudes within a region of the atmosphere defined by the same set of latitude and longitude coordinates. This provided an ideal opportunity to allow flight level focused continuous wave (CW) lidar backscatter measured at 9.11-micron wavelength and modeled aerosol backscatter from two aerosol optical counters to be compared with pulsed lidar aerosol backscatter data at 1.06- and 9.25-micron wavelengths. The best agreement between all sensors was found in the altitude region below 7 km, where backscatter values were moderately high at all three wavelengths. Above this altitude the pulsed lidar backscatter data at 1.06- and 9.25-micron wavelengths were higher than the flight level data obtained from the CW lidar or derived from the optical counters, suggesting sample volume effects were responsible for this. Aerosol microphysics analysis of data near Japan revealed a strong sea-salt aerosol plume extending upward from the marine boundary layer. On the basis of sample volume differences, it was found that large particles were of different composition compared with the small particles for low backscatter conditions.

Wide-Area Persistent Energy-Efficient Maritime Sensing

DTIC Science & Technology

2015-09-30

Matt Reynolds, Lefteris Kampianakis, and Andreas Pedrosse-Engel at UW designed and tested a Software Defined Radar testbed as well as an Arduino - based ...hardware based on a software-defined radio platform. 2) Development of a standalone Arduino - based backscatter node. 3) Analysis of the limits of the... Arduino - based node that can modulate radar backscatter with data received from a sensor using a low-power Arduino Nano processor. Figure 5 shows a

The Seismic Broad Band Western Mediterranean (wm) Network and the Obs Fomar Pool: Current state and Obs activities.

NASA Astrophysics Data System (ADS)

Pazos, Antonio; Davila, Jose Martin; Buforn, Elisa; Bezzeghoud, Mourad; Harnafi, Mimoun; Mattesini, Mauricio; Caldeira, Bento; Hanka, Winfried; El Moudnib, Lahcen; Strollo, Angelo; Roca, Antoni; Lopez de Mesa, Mireya; Dahm, Torsten; Cabieces, Roberto

2016-04-01

The Western Mediterranean (WM) seismic network started in 1996 as an initiative of the Royal Spanish Navy Observatory (ROA) and the Universidad Complutense de Madrid (UCM), with the collaboration of the GeoForschungsZentrum (GFZ) of Potsdam. A first broad band seismic station (SFUC) was installed close to Cádiz (South Spain). Since then, additional stations have been installed in the Ibero-Moghrebian region. In 2005, the "WM" code was assigned by the FDSN and new partners were jointed: Evora University (UEVO, Portugal), the Scientifique Institute of Rabat (ISRABAT, Morocco), and GFZ. Now days, the WM network is composed by 15 BB stations, all of them with Streckaisen STS-2 or STS-2.5 sensors, Quanterra or Earthdata digitizers and SeiscomP. Most them have co-installed a permanent geodetic GPS stations, and some them also have an accelerometer. There are 10 stations deployed in Spanish territory (5 in the Iberian peninsula, 1 in Balearic islands and 4 in North Africa Spanish places) with VSAT or Internet communications, 2 in Portugal (one of them without real time), and 3 in Morocco (2 VSAT and 1 ADSL). Additionally, 2 more stations (one in South Spain and one in Morocco) will be installed along this year. Additionally ROA has deployed a permanent real time VBB (CMG-3T: 360s) station at the Alboran Island. Due to the fact that part of the seismic activity is located at marine areas, and also because of the poor geographic azimuthal coverage at some zones provided by the land stations (specially in the SW of the San Vicente Cape area), ROA and UCM have acquired six broad band "LOBSTERN" OBS, manufactured by KUM (Kiel, Germany), conforming the OBS FOMAR pool. Three of them with CMG-40T sensor and the other with Trillium 120. These OBS were deployed along the Gibraltar strait since January to November 2014 to study the microseismicity in the Gibraltar strait area. In September 2015 FOMAR network has been deployed in SW of the San Vicente Cape for 8 months as a part of ALERTES-RIM project. In this work the current state and future plans of the WM network, the results of the Gibraltar strait campaign and San Vicente Cape OBS experiment are shown.

Ship Noise in the SW Indian Ocean Recorded by Ocean Bottom Seismic and Hydroacoustic Sensors

NASA Astrophysics Data System (ADS)

Barruol, G.; Dreo, R.; Fontaine, F. R.; Scholz, J. R.; Sigloch, K.

2016-12-01

In the frame of the RHUM-RUM project (Réunion Hotspot and Upper Mantle - Réunions Unterer Mantel, www.rhum-rum.net), a network of 57 ocean-bottom seismometers (OBS) has been installed on the ocean floor around La Réunion Island, but also on the neighbouring Southwest and Central Indian Ridges. The OBS were equipped by wide- and broad-band three-components seismic and hydroacoustic sensors. They were deployed in Nov. 2012, and depending on the configuration, they recorded for 8 to 13 months. Interestingly, part of the network was located beneath a NE-SW trending lane of very dense ship traffic connecting SE-Asia and the South-Atlantic region. By combining the vessel position - provided by AIS GPS data - and our geophysical data recorded on the ocean floor, we analyze the seismic and hydroacoustic ship signatures. From spectral analyzes, we show clear signals over the whole high-frequency range available from our instruments (between 1 and 50 Hz). The RHUM-RUM network covering latitude between 17 and 34° South, this allows to detect numerous vessels and to compare the noise characteristics (frequency content, polarization) of each vessel. We also investigate the possibility of using the polarization of the noise emitted by ships passing above an ocean-bottom seismometer, to help retrieving the orientation of the OBS horizontal components on the ocean floor in the geographic reference frame.

An investigation of the observability of ocean-surface parameters using GEOS-3 backscatter data

NASA Technical Reports Server (NTRS)

Miller, L. S.; Priester, R. W.

1978-01-01

The degree to which ocean surface roughness can be synoptically observed through use of the information extracted from the GEOS-3 backscattered waveform data was evaluated. Algorithms are given for use in estimating the radar sensed waveheight distribution or ocean-surface impulse response. Other factors discussed include comparisons between theoretical and experimental radar cross section values, sea state bias effects, spatial variability of significant waveheight data, and sensor-related considerations.

Nitrogen dioxide observations from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument: Retrieval algorithm and measurements during DISCOVER-AQ Texas 2013

EPA Science Inventory

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument is a test bed for upcoming air quality satellite instruments that will measure backscattered ultraviolet, visible and near-infrared light from geostationary orbit. GeoTASO flew on the NASA F...

Turbulence Characterization and Control

DTIC Science & Technology

1975-07-01

backscatter experiment, measures the returns from density fluctuations over the lower 1000 ft. of the atmosphere. Microthermal sensors measure local... microthermal sensors mentioned above provide useful data of this type. In additiona an optical experiment capable of making quantitative...analysis of these data has been completed. During some of these experimental runs, microthermal and acoustic sounder data was also col- lected by

Optimization of wavelengths sets for multispectral reflectance imaging of rat olfactory bulb activation in vivo

NASA Astrophysics Data System (ADS)

Renaud, Rémi; Bendahmane, Mounir; Chery, Romain; Martin, Claire; Gurden, Hirac; Pain, Frederic

2012-06-01

Wide field multispectral imaging of light backscattered by brain tissues provides maps of hemodynamics changes (total blood volume and oxygenation) following activation. This technique relies on the fit of the reflectance images obtain at two or more wavelengths using a modified Beer-Lambert law1,2. It has been successfully applied to study the activation of several sensory cortices in the anesthetized rodent using visible light1-5. We have carried out recently the first multispectral imaging in the olfactory bulb6 (OB) of anesthetized rats. However, the optimization of wavelengths choice has not been discussed in terms of cross talk and uniqueness of the estimated parameters (blood volume and saturation maps) although this point was shown to be crucial for similar studies in Diffuse Optical Imaging in humans7-10. We have studied theoretically and experimentally the optimal sets of wavelength for multispectral imaging of rodent brain activation in the visible. Sets of optimal wavelengths have been identified and validated in vivo for multispectral imaging of the OB of rats following odor stimulus. We studied the influence of the wavelengths sets on the magnitude and time courses of the oxy- and deoxyhemoglobin concentration variations as well as on the spatial extent of activated brain areas following stimulation. Beyond the estimation of hemodynamic parameters from multispectral reflectance data, we observed repeatedly and for all wavelengths a decrease of light reflectance. For wavelengths longer than 590 nm, these observations differ from those observed in the somatosensory and barrel cortex and question the basis of the reflectance changes during activation in the OB. To solve this issue, Monte Carlo simulations (MCS) have been carried out to assess the relative contribution of absorption, scattering and anisotropy changes to the intrinsic optical imaging signals in somatosensory cortex (SsC) and OB model.

Observations of the Variability of Floc Sizes on the Louisiana Shelf

NASA Astrophysics Data System (ADS)

Sahin, Cihan; Sheremet, Alexandru

2014-05-01

The general principles of floc formation under variable turbulent stresses and sediment availability are well known, but the details of the dynamics are still unclear. Flocculation of primary particles occurs when these particles get close enough to collide, and a significant number of these collisions result in adhesion. Particle concentration, the intensity and number of collisions (turbulent shear) control the size of the flocs. However, aggregation transitions into fragmentation if the intensity of collisions or turbulent shear exceeds a certain threshold. In this case, a limiting maximum size might exist (Berhane et al., 1997; Dyer and Manning, 1999; Uncles et al., 2010). This study investigates the relation between SSC (suspended sediment concentration), turbulent stresses, and floc size using the high-resolution observations of suspended sediment concentration, flow and acoustic backscatter made for 2 weeks in Spring 2008 on the muddy Atchafalaya Shelf. During the experiment, pressure, near-bed current velocities, and acoustic backscatter profiles were sampled using a downward-pointing 1500-kHz PC-ADP (Pulse-Coherent Acoustic Doppler Profiler, Sontek/YSI). In addition, a downward-pointing single frequency ABS (Acoustic Backscatter Sensor, 700-kHz, Marine Electronics, Isle of Guernsey) measured the intensity of acoustic return in the first meter above bed. Thus, acoustic backscatter profiles were observed by two different frequencies (700 kHz for the ABS and 1500 kHz for the PC-ADP). Direct SSC observations were provided by two OBS-3s at 15 and 40-cm above the bed, which sampled synchronously with the PC-ADP. Simultaneous profiles of SSC and the mean floc size at cm-scale vertical resolution were obtained using acoustic backscatter intensity at the different acoustic frequencies. For the calibration of the instruments, which involves estimation of the instruments system constants, the algorithm described in Sahin et al. (2013) was followed. The mean floc size profiles were obtained at each range bin and propagated along the backscattered profile using the implicit iterative approach, which is based on calculation of SSC and mean size iteratively until the values in the last two iterations converge (Sahin, under review). Estimated SSC profiles are in agreement with OBS point measurements with a correlation coefficient of 0.88 and 0.12 kg/m3 RMS error. The range of floc size estimates is consistent with the floc-size measurements in 2006 at the same site. Turbulent shear profiles were estimated using the current velocity profiles measured by the PC-ADP. As a first step, the friction velocities are estimated following Lacy et. al. (2005) by fitting the logarithmic profiles in a least-square sense to the current velocity profiles outside the wave boundary layer (Safak et al., 2013), which can then be used to approximate the dissipation of turbulent kinetic energy and the turbulent shear for each bin. The detailed investigation of the resulting SSC, floc-size and the turbulent shear rate profiles showed that low-to-mid values of shear rate promotes flocculation by increasing cohesive sediment particle collision. However, higher turbulent shear strongly affects large flocs, which have weaker internal bonds than those of the primary particles. These field observations support the findings observed in several previous experimental and numerical studies (Parker et al., 1972; Dyer, 1989). Acknowledgements This research was supported by the Office of Naval Research funding of contracts N00014-10-1-0363 and N00014-11-1-0269. References Berhane, I., Sternberg R.W., Kineke G.C., Milligan T.G., Kranck, K., 1997. The variability of suspended aggregates on the Amazon Continental Shelf. Continental Shelf Research 17, 267-285. Dyer, K. R., 1989. Sediment processes in estuaries: future research requirements. Journal of Geophysical Research 97, 14327-14339. Dyer, K. R., Manning A.J., 1999. Observation of size, settling velocity and effective density of flocs, and their fractal dimensions. J. Sea. Res., 41, 87-95. Hay, A.E. and Sheng J., 1992. Vertical Profiles of Suspended Sand Concentration and Size From Multifrequency Acoustic Backscatter. J. Geophys. Res., 97, C10, doi:10.1029/92JC01240. Lacy, J.R., Sherwood, C.R., Wilson, D.J., Chisholm, T.A., Gelfenbaum, G.R., 2005. Characteristics of suspended particles at an 11 hour anchor station in San Francisco Bay. Journal of Geophysical Research 110, C06014, http://dx.doi.org/10.1029/2003JC001814. Parker, D.S., Kaufman, and W.J., Jenkins, D., 1972. Floc breakup in turbulent processes. Journal of the Sanitary Engineering Division, ASCE , SA1, pp. 79-99. Safak, I., Allison M. A., Sheremet A., 2013. Floc variability under changing turbulent stresses and sediment availability on a wave energetic muddy shelf. Continental Shelf Research 53, 1-10, http://dx.doi.org/10.1016/j.csr.2012.11.015. Sahin, C., Safak I., Hsu T.-J., Sheremet A., 2013. Observations of suspended sediment stratification from acoustic backscatter in muddy environments. Marine Geology 336, 24-32, http://dx.doi.org/10.1016/j.margeo.2012.12.001. Sahin, C., under review. Investigation of the variability of floc sizes on the Louisiana Shelf using acoustic estimates of cohesive sediment properties. Uncles, R.J., Bale A.J., Stephens J.A., Frickers P.E., Harris, C., 2010. Observations of floc sizes in a muddy estuary. Estuarine, Coastal and Shelf Science 87, 186-196.

OPTICAL FIBRES AND FIBREOPTIC SENSORS: Fibreoptic distributed temperature sensor with spectral filtration by directional fibre couplers

NASA Astrophysics Data System (ADS)

Kuznetsov, A. G.; Babin, Sergei A.; Shelemba, Ivan S.

2009-11-01

We demonstrate a Raman-based all-fibre temperature sensor utilising a pulsed erbium fibre laser. The sensor is made of a standard single-mode telecom fibre, SMF-28, and includes a number of directional couplers as band-pass filters. The temperature profile along a 7-km fibreoptic line is measured with an accuracy of 2oC and a spatial resolution of 10 m. In data processing, we take into account the difference in attenuation between the spectral components of the backscatter signal.

Ocean Bottom Seismometer Augmentation of the Philippine Sea Experiment (OBSAPS) Cruise Report

DTIC Science & Technology

2011-09-01

single 77.5Hz M-sequence on six OBSAPS receivers: (from bottom to top) the vertical geophone on the North OBS ( blue ), the hydrophone module on the...wet end electronics (pressure sensor, hydrophone and octopus ) to the spare J15-3 S/N 14 and re-deployed the transducer and tow body assembly. We then...our wet end electronics (hydrophone, pressure sensor and octopus ) to the S/N 11 unit and re-deployed. The repaired J15-3 S/N 11 unit performed

Airborne lidar measurements of El Chichon stratospheric aerosols, October 1982 to November 1982

NASA Technical Reports Server (NTRS)

Mccormick, M. P.; Osborn, M. T.

1985-01-01

A coordinated flight mission to determine the spatial distribution and aerosol characteristics of the El Chichon produced stratospheric aerosol was flown in October to November 1982. The mission covered 46 deg N to 46 deg S and included rendezvous between balloon-, airplane-, and satellite-borne sensors. The lidar data from the flight mission are presented. Representative profiles of lidar backscatter ratio, plots of the integrated backscattering function versus latitude, and contours of backscatter mixing ratio versus altitude and latitude are given. In addition, tables containing numerical values of the backscatter ratio and backscattering functions versus altitude are supplied for each profile. The bulk of the material produced by the El Chichon eruptions of late March 10 to early April 1982 resided between latitudes from 5 to 7 deg S to 35 to 37 deg N and was concentrated above 21 km in a layer that peaked at 23 to 25 km. In this latitude region, peak scattering ratios at a wavelength of 0.6943 micron were approximately 24. The results of this mission are presented in a ready-to-use format for atmospheric and climatic studies.

OBSIP: Advancing Capabilities and Expanding the Ocean Bottom Seismology Community

NASA Astrophysics Data System (ADS)

Aderhold, K.; Evers, B.

2016-12-01

The Ocean Bottom Seismograph Instrument Pool (OBSIP) is a National Science Foundation sponsored instrument facility that provides ocean bottom seismometers (OBS) and technical support for research in the areas of marine geology, seismology, and geodynamics. OBSIP is comprised of an OBSIP Management Office (OMO) and three Institutional Instrument Contributors (IICs), who each contribute instruments and technical support to the pool. OBSIP operates both short period and broadband OBS instruments with a variety of capabilities to operate in shallow or deep water over both short and long term durations. Engineering developments at the IICs include capability for freshwater deployments, increased recording duration (15+ months), more efficient recovery systems, and sensor upgrades for a less heterogeneous fleet. OBSIP will provide instruments for three experiments in 2016 with deployments along a 1500 km transect in the South Atlantic, a large active-source experiment on the Chilean megathrust, and the very first seismometers ever deployed in Yellowstone Lake. OBSIP OMO strives to lower the barrier to working with OBS data by performing quality checks on data, investigating and responding to community questions, and providing data products like horizontal orientation calculations. This has resulted in a significant increase in new users to OBS data, especially for the open data sets from community seismic experiments. In 2015 the five-year Cascadia Initiative community seismic experiment concluded with over 250 OBS deployments and recoveries in an extensive grid off-shore Washington, Oregon, and California. The logistics of the Cascadia Initiative were challenging, but lessons were learned and efficiencies have been identified for implementation in future experiments. Large-scale community seismic experiments that cross the shoreline like the Cascadia Initiative and the Eastern North American Margin experiment have led to the proposal of even more ambitious endeavors like the Subduction Zone Observatory. OBSIP also is working to develop international collaboration and networking between OBS operators and researchers through special interest group meetings and the biannual OBS Symposium, to be held again in Fall 2017.

Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) Flight Testing of the Lidar Sensor

NASA Technical Reports Server (NTRS)

Soreide, David C.; Bogue, Rodney K.; Ehernberger, L. J.; Hannon, Stephen M.; Bowdle, David A.

2000-01-01

The purpose of the ACLAIM program is ultimately to establish the viability of light detection and ranging (lidar) as a forward-looking sensor for turbulence. The goals of this flight test are to: 1) demonstrate that the ACLAIM lidar system operates reliably in a flight test environment, 2) measure the performance of the lidar as a function of the aerosol backscatter coefficient (beta), 3) use the lidar system to measure atmospheric turbulence and compare these measurements to onboard gust measurements, and 4) make measurements of the aerosol backscatter coefficient, its probability distribution and spatial distribution. The scope of this paper is to briefly describe the ACLAIM system and present examples of ACLAIM operation in flight, including comparisons with independent measurements of wind gusts, gust-induced normal acceleration, and the derived eddy dissipation rate.

Biogeochemical sensor performance in the SOCCOM profiling float array

NASA Astrophysics Data System (ADS)

Johnson, Kenneth S.; Plant, Joshua N.; Coletti, Luke J.; Jannasch, Hans W.; Sakamoto, Carole M.; Riser, Stephen C.; Swift, Dana D.; Williams, Nancy L.; Boss, Emmanuel; Haëntjens, Nils; Talley, Lynne D.; Sarmiento, Jorge L.

2017-08-01

The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) program has begun deploying a large array of biogeochemical sensors on profiling floats in the Southern Ocean. As of February 2016, 86 floats have been deployed. Here the focus is on 56 floats with quality-controlled and adjusted data that have been in the water at least 6 months. The floats carry oxygen, nitrate, pH, chlorophyll fluorescence, and optical backscatter sensors. The raw data generated by these sensors can suffer from inaccurate initial calibrations and from sensor drift over time. Procedures to correct the data are defined. The initial accuracy of the adjusted concentrations is assessed by comparing the corrected data to laboratory measurements made on samples collected by a hydrographic cast with a rosette sampler at the float deployment station. The long-term accuracy of the corrected data is compared to the GLODAPv2 data set whenever a float made a profile within 20 km of a GLODAPv2 station. Based on these assessments, the fleet average oxygen data are accurate to 1 ± 1%, nitrate to within 0.5 ± 0.5 µmol kg-1, and pH to 0.005 ± 0.007, where the error limit is 1 standard deviation of the fleet data. The bio-optical measurements of chlorophyll fluorescence and optical backscatter are used to estimate chlorophyll a and particulate organic carbon concentration. The particulate organic carbon concentrations inferred from optical backscatter appear accurate to with 35 mg C m-3 or 20%, whichever is larger. Factors affecting the accuracy of the estimated chlorophyll a concentrations are evaluated.