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1

DESIGN, FABRICATION, ASSEMBLY AND BENCH TESTING OF A TEXACO INFRARED RATIO PYROMETER SYSTEM FOR THE MEASUREMENT OF REACTION CHAMBER TEMPERATURE  

SciTech Connect

Reliable measurement of gasifier reaction chamber temperature is important for the proper operation of slagging, entrained-flow gasification processes. Historically, thermocouples have been used as the main measurement technique, with the temperature inferred from syngas methane concentration being used as a backup measurement. While these have been sufficient for plant operation in many cases, both techniques suffer from limitations. The response time of methane measurements is too slow to detect rapid upset conditions, and thermocouples are subject to long-term drift, as well as slag attack, which eventually leads to failure of the thermocouple. Texaco's Montebello Technology Center (MTC) has developed an infrared ratio pyrometer system for measuring gasifier reaction chamber temperature. This system has a faster response time than both methane and thermocouples, and has been demonstrated to provide reliable temperature measurements for longer periods of time when compared to thermocouples installed in the same MTC gasifier. In addition, the system can be applied to commercial gasifiers without any significant scale-up issues. The major equipment items, the purge system, and the safety shutdown system in a commercial plant are essentially identical to the prototypes at MTC. The desired result of this DOE program is ''a bench-scale prototype, either assembled or with critical components (laboratory) tested in a convincing manner.'' The prototype of the pyrometer system (including gasifier optical access port) that was designed, assembled and tested for this program, has had previous prototypes that have been built and successfully tested under actual coal and coke gasification conditions in three pilot units at MTC. It was the intent of the work performed under the auspices of this program to review and update the existing design, and to fabricate and bench test an updated system that can be field tested in one or more commercial gasifiers during a follow on phase of this program. For all intents and purposes, the development, bench testing and pilot unit testing of this temperature measurement system has already been done, and was mostly a matter of getting the hardware ready for a commercial field test. The benefits of field-testing are (1) Texaco will gain long-term commercial operating experience and (2) commercial gasifier operators will gain confidence that this system can perform reliably under true commercial plant conditions. This work was performed by Texaco at its Montebello Technology Center in South El Monte, California.

Tom Leininger

2001-03-31

2

Development of a Multi-Point Pyrometer System (MPPS) for measuring surface temperature and emissivity  

SciTech Connect

In support of the US DOE MHD research program, the Diagnostic Instrumentation and Analysis Laboratory (DIAL) has been actively engaged in developing and applying advanced optical diagnostic techniques and instrumentation systems to high temperature coal-fired gas streams for over a decade. One of the earliest diagnostic systems developed by DIAL was a two color pyrometer (TCP). In this system, two commercial single-color pyrometers and a microprocessor system were used to form a TCP which can make accurate measurements of surfaces of unknown emissivity and temperature. This system has been used extensively to make measurements in support of the national MHD program. This report describes this system.

Benton, R.D.; Jang, Ping-Rey

1993-06-01

3

Streaked Optical Pyrometer System for Laser-Driven Shock-Wave Experiments on OMEGA  

SciTech Connect

The temperature of laser-driven shock waves is of interest to inertial confinement fusion and high-energy-density physics. We report on a streaked optical pyrometer that measures the self-emission of laser-driven shocks simultaneously with a velocity interferometer system for any reflector (VISAR). Together these diagnostics are used to obtain the temporally and spatially resolved temperatures of ~Mbar shocks driven by the OMEGA laser. We provide a brief description of the diagnostic and how it is used with VISAR. Key spectral calibration results are discussed and important characteristics of the recording system are presented.

Miller, J.E.; Boehly, T.R.; Melchior, Meyerhofer, D.D.; Celliers, P.M.; Eggert, J.H.; Hicks, D.G.; Sorce, C.M.; Oertel, J.A.; Emmel, P.M.

2007-03-23

4

Fast fiber-optic multi-wavelength pyrometer  

NASA Astrophysics Data System (ADS)

A fast fiber-optic multi-wavelength pyrometer was developed for the ultraviolet-visible-near infrared spectra from 200 nm to 1700 nm using a CCD detector and an InGaAs detector. The pyrometer system conveniently and quickly provides the sufficient choices of multiple measurement wavelengths using optical diffraction, which avoids the use of narrow-band filters. Flexible optical fibers are used to transmit the radiation so the pyrometer can be used for temperature measurements in harsh environments. The setup and calibrations (wavelength calibration, nonlinearity calibration, and radiation response calibration) of this pyrometer system were described. Development of the multi-wavelength pyrometer involved optimization of the bandwidth and temperature discrimination of the multiple spectra data. The analysis results showed that the wavelength intervals, ??CCD = 30 nm and ??InGaAs = 50 nm, are the suitable choices as a tradeoff between the simple emissivity model assumption and the multiple signal discrimination. The temperature discrimination was also quantificationally evaluated for various wavelengths and temperatures. The measurement performance of the fiber-optic multi-wavelength pyrometer was partially verified through measurements with a high-temperature blackbody and actual hot metals. This multi-wavelength pyrometer can be used for remote high-temperature measurements.

Fu, Tairan; Tan, Peng; Pang, Chuanhe; Zhao, Huan; Shen, Yi

2011-06-01

5

Fast fiber-optic multi-wavelength pyrometer.  

PubMed

A fast fiber-optic multi-wavelength pyrometer was developed for the ultraviolet-visible-near infrared spectra from 200 nm to 1700 nm using a CCD detector and an InGaAs detector. The pyrometer system conveniently and quickly provides the sufficient choices of multiple measurement wavelengths using optical diffraction, which avoids the use of narrow-band filters. Flexible optical fibers are used to transmit the radiation so the pyrometer can be used for temperature measurements in harsh environments. The setup and calibrations (wavelength calibration, nonlinearity calibration, and radiation response calibration) of this pyrometer system were described. Development of the multi-wavelength pyrometer involved optimization of the bandwidth and temperature discrimination of the multiple spectra data. The analysis results showed that the wavelength intervals, ??(CCD) = 30 nm and ??(InGaAs) = 50 nm, are the suitable choices as a tradeoff between the simple emissivity model assumption and the multiple signal discrimination. The temperature discrimination was also quantificationally evaluated for various wavelengths and temperatures. The measurement performance of the fiber-optic multi-wavelength pyrometer was partially verified through measurements with a high-temperature blackbody and actual hot metals. This multi-wavelength pyrometer can be used for remote high-temperature measurements. PMID:21721719

Fu, Tairan; Tan, Peng; Pang, Chuanhe; Zhao, Huan; Shen, Yi

2011-06-01

6

C2 Swan spectrum used as a molecular pyrometer in transferred arc and the influence noise to signal ratio on the temperature values  

NASA Astrophysics Data System (ADS)

The C2 Swan system molecular emission spectrum is frequently observed in arc plasmas containing hydrocarbons. The spectra emitted from 5 kw in the transferred arc reactor at atmospheric pressure by CH4/CO2/Ar mixture are recorded with the help of an optical system consisting of a linear CCD array coupled with 2m spectrometer. The rotational temperature of 4300±300K is found from the experimental Abel inverted spectra in the arc center after a point-to-point comparison of the spectrum with a computer simulated one. The influence of the noise to signal ratio has been studied, if the noise to signal ratio is about 10% we found an error of 7% at temperature 3000K and 10% at 6000K.

Nassar, H.

2014-05-01

7

Multicolor pyrometer for materials processing in space  

NASA Technical Reports Server (NTRS)

This report documents the work performed by Physical Sciences Inc. (PSI), under contract to NASA JPL, during a 2.5-year SBIR Phase 2 Program. The program goals were to design, construct, and program a prototype passive imaging pyrometer capable of measuring, as accurately as possible, and controlling the temperature distribution across the surface of a moving object suspended in space. These goals were achieved and the instrument was delivered to JPL in November 1989. The pyrometer utilizes an optical system which operates at short wavelengths compared to the peak of the black-body spectrum for the temperature range of interest, thus minimizing errors associated with a lack of knowledge about the heated sample's emissivity. To cover temperatures from 900 to 2500 K, six wavelengths are available. The preferred wavelength for measurement of a particular temperature decreases as the temperature increases. Images at all six wavelengths are projected onto a single CCD camera concurrently. The camera and optical system have been calibrated to relate the measured intensity at each pixel to the temperature of the heated object. The output of the camera is digitized by a frame grabber installed in a personal computer and analyzed automatically to yield temperature information. The data can be used in a feedback loop to alter the status of computer-activated switches and thereby control a heating system.

Frish, M. B.; Frank, J.; Baker, J. E.; Foutter, R. R.; Beerman, H.; Allen, M. G.

1990-01-01

8

Two-color optical charge-coupled-device-based pyrometer using a two-peak filter  

NASA Astrophysics Data System (ADS)

A two-color optical charge-coupled-device (CCD)-based pyrometer was developed using a multipeak interference filter with a color CCD sensor to measure multicolor signals with specified wavelengths. The effective and simple method adjusts the fixed spectrum response characteristics of a color CCD to allow improved temperature measurements. This pyrometer system not only has the advantage of traditional two-color (two-wavelength) pyrometry, but also overcomes the restrictions of color CCDs that can only be applied in waveband measurements. The measurement performance of the system using a two-peak filter (? _1 = 643 nm,? _2 = 564 nm) was evaluated by blackbody experiments. The results show that the low temperature detection limit is increased about 200 K with an increase in the sensitivity of the measured signals compared with the original system without two-peak filter [Fu, et al., Opt. Laser Technol. 42, 586 (2010)]. And the effective temperature range is also increased when T > 1233 K. The measured ratio C_R /C_G is monotonically relative to the temperature, which simplifies the measurements. The temperature sensitivity of 2.49 is larger and more uniform than the temperature sensitivity of 1.36 in the previous original system. Thus, the measurement performance of the new system is greatly improved. Finally, as an application, the surface temperature distribution of stainless steel sample in hot environments was determined by this new CCD-based pyrometer. The results agree well with the spectrometer-based results and further verify the applicability of the new system.

Fu, Tairan; Zhao, Huan; Zeng, Jun; Zhong, Maohua; Shi, Congling

2010-12-01

9

IR optical fiber-based noncontact pyrometer for drop tube instrumentation  

NASA Technical Reports Server (NTRS)

The design of a two color pyrometer with infrared optical fiber bundles for collection of the infrared radiation is described. The pyrometer design is engineered to facilitate its use for measurement of the temperature of small, falling samples in a microgravity materials processing experiment using a 100 meter long drop tube. Because the samples are small and move rapidly through the field of view of the pyrometer, the optical power budget of the detection system is severly limited. Strategies for overcoming this limitation are discussed.

May, R. G.; Moneyhun, S.; Saleh, W.; Sudeora, S.; Claus, R. O.; Buoncristiani, A. M.

1989-01-01

10

The application analyses for primary spectrum pyrometer  

NASA Astrophysics Data System (ADS)

In the applications of primary spectrum pyrometry, based on the dynamic range and the minimum sensibility of the sensor, the application issues, such as the measurement range and the measurement partition, were investigated through theoretical analyses. For a developed primary spectrum pyrometer, the theoretical predictions of measurement range and the distributions of measurement partition were presented through numerical simulations. And the measurement experiments of high-temperature blackbody and standard temperature lamp were processed to further verify the above theoretical analyses and numerical results. Therefore the research in the paper provides the helpful supports for the applications of primary spectrum pyrometer and other radiation pyrometers.

Fu, Tairan; Cheng, Xiaofang; Zhong, Maohua

2007-12-01

11

Self-calibrated active pyrometer for furnace temperature measurements  

DOEpatents

Pyrometer with a probe beam superimposed on its field-of-view for furnace temperature measurements. The pyrometer includes a heterodyne millimeter/sub-millimeter-wave or microwave receiver including a millimeter/sub-millimeter-wave or microwave source for probing. The receiver is adapted to receive radiation from a surface whose temperature is to be measured. The radiation includes a surface emission portion and a surface reflection portion which includes the probe beam energy reflected from the surface. The surface emission portion is related to the surface temperature and the surface reflection portion is related to the emissivity of the surface. The simultaneous measurement of surface emissivity serves as a real time calibration of the temperature measurement. In an alternative embodiment, a translatable base plate and a visible laser beam allow slow mapping out of interference patterns and obtaining peak values therefor. The invention also includes a waveguide having a replaceable end portion, an insulating refractory sleeve and/or a source of inert gas flow. The pyrometer may be used in conjunction with a waveguide to form a system for temperature measurements in a furnace. The system may employ a chopper or alternatively, be constructed without a chopper. The system may also include an auxiliary reflector for surface emissivity measurements.

Woskov, Paul P. (Bedford, MA); Cohn, Daniel R. (Chestnuthill, MA); Titus, Charles H. (Newtown Square, PA); Surma, Jeffrey E. (Kennewick, WA)

1998-01-01

12

DESIGN, FABRICATION AND BENCH TESTNG OF A TEXACO INFRARED RATIO PYROMETER SYSTEM FOR THE MEASUREMENT OF GASIFIER REACTION CHAMBER TEMPERATURE  

SciTech Connect

The cooperative agreement between Texaco and Polk Power has been revised by Polk Power and ChevronTexaco several times already. Lawyers from both Polk Power and ChevronTexaco are in the process to include the issues related to the ownership transfer of the Texaco gasification unit in the agreement and finalize the draft. The modification fieldwork and testing will start once the cooperative agreement is signed with Polk Power.

Thomas F. Leininger; Hua-Min Huang

2003-04-01

13

Two-Band Pyrometers Detect Hydrogen Fires  

NASA Technical Reports Server (NTRS)

Two-band infrared pyrometers detect small hydrogen fires at greater distances in full daylight being developed. Detectors utilize part of infrared spectrum in which signals from hydrogen flames 10 to the 3rd power to 10 to the 4th power times as intense as ultraviolet region of current detectors. Utilize low-loss infrared lenses for focusing and for limiting fields of view to screen out spurious signals from nearby sources. Working distances of as much as 100 meters possible. Portable, battery-powered unit gives audible alarm, in form of increase in frequency of tone, when aimed at hydrogen fire.

Collins, J. David; Youngquist, Robert C.; Simmons, Stephen M.

1993-01-01

14

Development of three-wavelength CCD image pyrometer used for the temperature field measurements of continuous casting billets  

SciTech Connect

This paper develops an imaging based three-color pyrometer for the monitoring of temperature distribution in a continuous casting billet. A novel optical device, together with an embedded electronic system, is designed to sequentially collect a dark image and three thermal images with specified wavelengths on a same monochromatic charge-coupled-device (CCD). The three thermal images provide the basis for the determination of target temperature, while the dark image is used to online eliminate the dark noise of CCD with a differential method. This image pyrometer is not only independent of target emissivity but also overcomes the dissimilarity of measuring accuracy between the micro-sensors of CCD resulted from the non-uniformity of pixels’ intensity response and the vignetting of optical system. Furthermore, a precise two-color temperature field measuring model on the CCD pyrometer is established, based on which a self-adaptive light-integration mechanism is presented. Compared with the traditional fixed light-integration method, the measuring range of the pyrometer is greatly extended and its sensitivity in low temperature segment is improved. The test results in a steel factory demonstrate that the pyrometer is capable of meeting the requirement of surface temperature measurements about casting billets. Reliability and accuracy of measurement results are also discussed herein.

Xie, Zhi; Bai, Haicheng [State Key Laboratory of Synthetical Automation for Process Industries, School of Information Science and Engineering, Northeastern University, Shenyang 110819 (China)] [State Key Laboratory of Synthetical Automation for Process Industries, School of Information Science and Engineering, Northeastern University, Shenyang 110819 (China)

2014-02-15

15

Development of three-wavelength CCD image pyrometer used for the temperature field measurements of continuous casting billets.  

PubMed

This paper develops an imaging based three-color pyrometer for the monitoring of temperature distribution in a continuous casting billet. A novel optical device, together with an embedded electronic system, is designed to sequentially collect a dark image and three thermal images with specified wavelengths on a same monochromatic charge-coupled-device (CCD). The three thermal images provide the basis for the determination of target temperature, while the dark image is used to online eliminate the dark noise of CCD with a differential method. This image pyrometer is not only independent of target emissivity but also overcomes the dissimilarity of measuring accuracy between the micro-sensors of CCD resulted from the non-uniformity of pixels' intensity response and the vignetting of optical system. Furthermore, a precise two-color temperature field measuring model on the CCD pyrometer is established, based on which a self-adaptive light-integration mechanism is presented. Compared with the traditional fixed light-integration method, the measuring range of the pyrometer is greatly extended and its sensitivity in low temperature segment is improved. The test results in a steel factory demonstrate that the pyrometer is capable of meeting the requirement of surface temperature measurements about casting billets. Reliability and accuracy of measurement results are also discussed herein. PMID:24593387

Xie, Zhi; Bai, Haicheng

2014-02-01

16

Method and Apparatus for Polaradiometric Pyrometer  

NASA Technical Reports Server (NTRS)

A radiation pyrometer for measuring the true temperature of a body is provided by detecting and measuring thermal radiation from the body based on the principle that the effects of angular emission I(sub 1) and reflection I(sub 2) on the polarization states p and s of radiation are complementary such that upon detecting the combined partial polarization state components I(sub p) = I(sub 1p) + I(sub 2p) and I(sub s) = I(sub 1s) + I(sub 2s) and adjusting the intensity of the variable radiation source of the reflected radiation I(sub 2) until the combined partial radiation components I(sub p) and I(sub s) are equal, the effects of emissivity as well as diffusivity of the surface of the body are eliminated, thus obviating the need for any post processing of brightness temperature data.

Abtahi, Ali A. (inventor)

1994-01-01

17

Temperature Measurement of Ceramic Materials Using a Multiwavelength Pyrometer  

NASA Technical Reports Server (NTRS)

The surface temperatures of several pure ceramic materials (alumina, beryllia, magnesia, yittria and spinel) in the shape of pellets were measured using a multiwavelength pyrometer. In one of the measurements, radiation signal collection is provided simply by an optical fiber. In the other experiments, a 4.75 inch (12 cm) parabolic mirror collects the signal for the spectrometer. Temperature measurement using the traditional one- and two-color pyrometer for these ceramic materials is difficult because of their complex optical properties, such as low emissivity which varies with both temperature and wavelength. In at least one of the materials, yittria, the detected optical emission increased as the temperature was decreased due to such emissivity variation. The reasons for such changes are not known. The multiwavelength pyrometer has demonstrated its ability to measure surface temperatures under such conditions. Platinum electrodes were embedded in the ceramic pellets for resistance measurements as the temperature changed.

Ng, Daniel; Fralick, Gustave

1999-01-01

18

Temperature measurement in WTE boilers using suction pyrometers.  

PubMed

The temperature of the flue-gas in the post combustion zone of a waste to energy (WTE) plant has to be maintained within a fairly narrow range of values, the minimum of which is prescribed by the European Waste Directive 2000/76/CE, whereas the maximum value must be such as to ensure the preservation of the materials and the energy efficiency of the plant. A high degree of accuracy in measuring and controlling the aforementioned temperature is therefore required. In almost the totality of WTE plants this measurement process is carried out by using practical industrial thermometers, such as bare thermocouples and infrared radiation (IR) pyrometers, even if affected by different physical contributions which can make the gas temperature measurements incorrect. The objective of this paper is to analyze errors and uncertainties that can arise when using a bare thermocouple or an IR pyrometer in a WTE plant and to provide a method for the in situ calibration of these industrial sensors through the use of suction pyrometers. The paper describes principle of operation, design, and uncertainty contributions of suction pyrometers, it also provides the best estimation of the flue-gas temperature in the post combustion zone of a WTE plant and the estimation of its expanded uncertainty. PMID:24248279

Rinaldi, Fabio; Najafi, Behzad

2013-01-01

19

Temperature Measurement in WTE Boilers Using Suction Pyrometers  

PubMed Central

The temperature of the flue-gas in the post combustion zone of a waste to energy (WTE) plant has to be maintained within a fairly narrow range of values, the minimum of which is prescribed by the European Waste Directive 2000/76/CE, whereas the maximum value must be such as to ensure the preservation of the materials and the energy efficiency of the plant. A high degree of accuracy in measuring and controlling the aforementioned temperature is therefore required. In almost the totality of WTE plants this measurement process is carried out by using practical industrial thermometers, such as bare thermocouples and infrared radiation (IR) pyrometers, even if affected by different physical contributions which can make the gas temperature measurements incorrect. The objective of this paper is to analyze errors and uncertainties that can arise when using a bare thermocouple or an IR pyrometer in a WTE plant and to provide a method for the in situ calibration of these industrial sensors through the use of suction pyrometers. The paper describes principle of operation, design, and uncertainty contributions of suction pyrometers, it also provides the best estimation of the flue-gas temperature in the post combustion zone of a WTE plant and the estimation of its expanded uncertainty. PMID:24248279

Rinaldi, Fabio; Najafi, Behzad

2013-01-01

20

Direct emissivity measurements on liquids and corrections to multi-color pyrometers  

NASA Technical Reports Server (NTRS)

Optical pyrometry provides a means for non-contact temperature measurements whose accuracy depends on the accuracy with which specimen emittance is known. Two methods for obtaining the required emittance data are discussed in which the emittance is determined from measurements of the wavelength or polarization dependence of light emitted by the specimen. The spectral technique, multi-color pyrometry, yields apparent values for specimen emittance and temperature from emitted intensity measurements at two or more wavelengths. Emittance corrections cannot be eliminated by increasing the number of spectral intensity measurements required by an n-color pyrometer. Even if this were possible, the accuracy of temperature measurements by n-color pyrometry decreases with n such that pyrometers that require four intensity measurements would be impractical. In contrast, emittance values and corrections for one-color pyrometers can be accurately measured by the polarized light technique. The polarized light technique involves measurement of the degree of polarization for light emitted at an angle of 45 deg to the specimen normal. The reflectivities (r) for light polarized parallel (p) and normal (n) to the plane of emission are related by r(p) = r(n) squared. This leads to a simple relation between the intensity ratio for light emitted in the two polarized states and the emittance, i.e., e(n) = 2 - I(p)/I(n). The true specimen temperature is also obtained if absolute intensities are measured. Delvelopment of the polarized light technique in combination with one-color optical pyrometry is recommended to achieve accurate non-contact temperature measurements on liquids.

Nordine, Paul C.; Schiffman, Robert A.

1988-01-01

21

Use of a Multiwavelength Pyrometer in Several Elevated Temperature Aerospace Applications  

NASA Technical Reports Server (NTRS)

A multiwavelength pyrometer was developed for applications unique to aerospace environments. It was shown to be a useful and versatile technique for measuring temperature, even when the emissivity is unknown. It has also been used to measure the surface temperatures of ceramic zircomia thermal barrier coatings and alumina. The close agreement between pyrometer and thin film thermocouple temperatures provided an independent check. Other applications of the multiwavelength pyrometer are simultaneous surface and bulk temperature measurements of a transparent material, and combustion gas temperature measurement using a special probe interfaced to the multiwavelength pyrometer via an optical fiber. The multiwavelength pyrometer determined temperature by transforming the radiation spectrum in a broad wavelength region to produce a straight line (in a certain spectral region), whose intercept in the vertical axis gives the temperature. Implicit in a two-color pyrometer is the assumption of wavelength independent emissivity. Though the two data points of a two-color pyrometer similarly processed would result immediately in a similar straight line to give the unknown temperature, the two-color pyrometer lacks the greater data redundancy of the multiwavelength pyrometer, which enables it to do so with improved accuracy. It also confirms that emissivity is indeed wavelength independent, as evidenced by a multitude of the data lying on a simple straight line. The multiwavelength pyrometer was also used to study the optical transmission properties of a nanostructured material from which a quadratic exponential functional frequency dependence of its spectral transmission was determined. Finally, by operating the multiwavelength pyrometer in a very wide field of view mode, the surface temperature distribution of a large hot surface was obtained through measurement of just a single radiation spectrum.

Ng, Daniel; Fralick, Gustave

2001-01-01

22

Temperature measurement of aluminium on an extrusion press using the new BACO radiation pyrometer  

Microsoft Academic Search

A new sensitive lead sulphide cell pyrometer has been developed which enables the temperatures of aluminium extrusions to be continuously monitored or controlled during processing to about ± 10 degC. The narrow field of view (¾ in width at 7 ft viewing distance) enables the pyrometer to be mounted on the guillotine of the press to view the extrusion down

D. D. Beattie

1968-01-01

23

Evaluation of Raytek infrared pyrometer for continuous propellant temperature measurement  

NASA Technical Reports Server (NTRS)

The primary purpose of this evaluation was to determine if the Raytek IR pyrometer that was installed in the 600 gallon propellant mixers could be used to provide a continuous, accurate, reliable measurement of the propellant temperature during mixing. The Raytek infrared sensor is not recommended to be used for controlling propellant temperature nor for inspection buy-off. The first part of the evaluation was to determine the accuracy of the sensor in measuring the propellant temperature. The second part was to determine the reliability of the air purge design in preventing contamination of the IR window.

Dykstra, Mark D.

1990-01-01

24

The Rover Environmental Monitoring Station Ground Temperature Sensor: A Pyrometer for Measuring Ground Temperature on Mars  

PubMed Central

We describe the parameters that drive the design and modeling of the Rover Environmental Monitoring Station (REMS) Ground Temperature Sensor (GTS), an instrument aboard NASA’s Mars Science Laboratory, and report preliminary test results. REMS GTS is a lightweight, low-power, and low cost pyrometer for measuring the Martian surface kinematic temperature. The sensor’s main feature is its innovative design, based on a simple mechanical structure with no moving parts. It includes an in-flight calibration system that permits sensor recalibration when sensor sensitivity has been degraded by deposition of dust over the optics. This paper provides the first results of a GTS engineering model working in a Martian-like, extreme environment. PMID:22163405

Sebastián, Eduardo; Armiens, Carlos; Gómez-Elvira, Javier; Zorzano, María P.; Martinez-Frias, Jesus; Esteban, Blanca; Ramos, Miguel

2010-01-01

25

The Rover Environmental Monitoring Station Ground Temperature Sensor: a pyrometer for measuring ground temperature on Mars.  

PubMed

We describe the parameters that drive the design and modeling of the Rover Environmental Monitoring Station (REMS) Ground Temperature Sensor (GTS), an instrument aboard NASA's Mars Science Laboratory, and report preliminary test results. REMS GTS is a lightweight, low-power, and low cost pyrometer for measuring the Martian surface kinematic temperature. The sensor's main feature is its innovative design, based on a simple mechanical structure with no moving parts. It includes an in-flight calibration system that permits sensor recalibration when sensor sensitivity has been degraded by deposition of dust over the optics. This paper provides the first results of a GTS engineering model working in a Martian-like, extreme environment. PMID:22163405

Sebastián, Eduardo; Armiens, Carlos; Gómez-Elvira, Javier; Zorzano, María P; Martinez-Frias, Jesus; Esteban, Blanca; Ramos, Miguel

2010-01-01

26

Development of a multi-point two-color pyrometer for tube and wall temperature and emissivity measurement at the CFFF  

NASA Astrophysics Data System (ADS)

The Diagnostic Instrumentation and Analysis Laboratory (DIAL) has been actively engaged in developing and applying advanced optical diagnostic techniques and instrumentation systems to high temperature coal-fired gas streams for over a decade. DIAL's systems have been used primarily in support of the US Department of Energy's (DOE) magnetohydrodynamic (MHD) research program. One of the earliest diagnostic systems developed by DIAL was a two color pyrometer (TCP). The TCP is used to measure surface temperature and emissivity. This system has been used extensively to make measurements in support of the national MHD program. In this system, two commercial single-color pyrometers and a microprocessor system were used to form a TCP to make accurate measurements of surfaces of unknown emissivity and temperature. This paper describes an improvement in the DIAL TCP which provides for near simultaneous multipoint measurements, reduced dependence on electronic circuits, and a greatly improved data display system. Commercial two-color pyrometer systems are not suitable for our work because they do not provide for emissivity measurement. The emissivity measurement provides insight into changes in surface characteristics and is an important consideration in our work. A second and important reason for our development of this system is the need to make simultaneous measurements at widely separated points. Finally, the data measured by this system is stored on magnetic media and can be correlated with other measurements on the system, e.g. furnace, under study.

Benton, R. D.; Jang, P. R.

27

A sensitive time-resolved radiation pyrometer for shock-temperature measurements above 1500 K  

NASA Technical Reports Server (NTRS)

The general design, calibration, and performance of a new high-sensitivity radiation pyrometer are described. The pyrometer can determine time-resolved temperatures (as low as 1500 K) in shocked materials by measuring the spectral radiance of light emitted from shocked solid samples in the visible and near-infrared wavelength range (0.5-1.0 micron). The high sensitivity of the radiation pyrometer is attributed to the large angular aperture (0.06 sr), the large bandwidth per channel (up to 0.1 micron), the large photodiode detection areas (1.0 sq cm), and the small number of calibrated channels (4) among which light is divided.

Boslough, Mark B.; Ahrens, Thomas J.

1989-01-01

28

High-resolution surface temperature measurements on rotating turbine blades with an infrared pyrometer  

NASA Technical Reports Server (NTRS)

A high-resolution pyrometer was developed and tested on a modified turbine engine. The pyrometer was used to obtain temperature profiles of the viewed surface of turbine blades in the engine at tip speeds up to 366 meters per second. The combination of coherent fiber optics, a silicon avalanche detector, and high-speed electronics enabled surface resolution of a spot diameter of 0.05 centimeter. The data, in the form of temperature profiles, was obtained in near real time as a hard copy output from a computer display terminal. Temperatures measured with the pyrometer and with thermocouples agreed within 2 percent at temperatures between 977 to 1144 K.

Uguccini, O. W.; Pollack, F. G.

1976-01-01

29

Measuring Isotope Ratios Across the Solar System  

NASA Technical Reports Server (NTRS)

Stable isotope ratios in C, H, N, O and S are powerful indicators of a wide variety of planetary geophysical processes that can identify origin, transport, temperature history, radiation exposure, atmospheric escape, environmental habitability and biology [1]. For the Allan Hills 84001 meteorite, for example, the (sup 1)(sup 3)C/(sup 1)(sup 2)C ratio identifies it as a Mars (SNC) meteorite; the ??K/??Ar ratio tells us the last time the rock cooled to solid, namely 4 Gya; isotope ratios in (sup 3)He, (sup 2)(sup 1)Ne and (sup 3)?Ar show it was in space (cosmic ray exposure) for 10-20 million years; (sup 1)?C dating that it sat in Antarctica for 13,000 years before discovery; and clumped isotope analysis of (sup 1)?O(sup 1)(sup 3)C(sup 1)?O in its carbonate that it was formed at 18+/-4 ?C in a near-surface aqueous environment [2]. Solar System Formation

Webster, Chris R.; Mahaffy, Paul R.

2012-01-01

30

Multi-spectral pyrometer for gas turbine blade temperature measurement  

NASA Astrophysics Data System (ADS)

To achieve the highest possible turbine inlet temperature requires to accurately measuring the turbine blade temperature. If the temperature of blade frequent beyond the design limits, it will seriously reduce the service life. The problem for the accuracy of the temperature measurement includes the value of the target surface emissivity is unknown and the emissivity model is variability and the thermal radiation of the high temperature environment. In this paper, the multi-spectral pyrometer is designed provided mainly for range 500-1000°, and present a model corrected in terms of the error due to the reflected radiation only base on the turbine geometry and the physical properties of the material. Under different working conditions, the method can reduce the measurement error from the reflect radiation of vanes, make measurement closer to the actual temperature of the blade and calculating the corresponding model through genetic algorithm. The experiment shows that this method has higher accuracy measurements.

Gao, Shan; Wang, Lixin; Feng, Chi

2014-09-01

31

CO (Carbon Monoxide Mixing Ratio System) Handbook  

SciTech Connect

The main function of the CO instrument is to provide continuous accurate measurements of carbon monoxide mixing ratio at the ARM SGP Central Facility (CF) 60-meter tower (36.607 °N, 97.489 °W, 314 meters above sea level). The essential feature of the control and data acquisition system is to record signals from a Thermo Electron 48C and periodically calibrate out zero and span drifts in the instrument using the combination of a CO scrubber and two concentrations of span gas (100 and 300 ppb CO in air). The system was deployed on May 25, 2005.

Biraud, S

2011-02-23

32

Evaluation and comparison of three IR detectors and three amplifier designs for a new high-speed IR pyrometer  

NASA Astrophysics Data System (ADS)

At Los Alamos National Laboratory (LANL), a high-speed, four-wavelength, infrared (IR) pyrometer has been used for surface temperature measurements in shock-physics experiments for several years. The pyrometer uses solid-state detectors and a single fiber-optic cable for transmission of light from the target surface to the detectors. This instrument has recently been redesigned for an upcoming experiment at the Nevada Test Site (NTS). Three different IR detectors (two HgCdTe variants as well as the existing InSb chip) were compared for sensitivity, signal-to-noise ratio, and bandwidth. Of major concern was detector amplifier recovery time from overload saturation. In shock-physics experiments, a short but very bright precursor frequently accompanies shock breakout (often from trapped air). This precursor can saturate the amplifier and may "swamp-out" the signal of interest before the amplifier recovers. With this in mind, we evaluated two new amplifier designs by the Perry Amplifier Company for linearity, signal-to-noise characteristics, gain, and saturation recovery time. This paper describes experimental setup for detector comparison and results obtained. Furthermore, we discuss new amplifier design and suitability for high-speed infrared pyrometry in shock physics experiments.

Young, J. A.; Borror, S.; Obst, A. W.; Payton, J. R.; Seifter, A.

2005-08-01

33

Flexible Conversion Ratio Fast Reactor Systems Evaluation  

SciTech Connect

Conceptual designs of lead-cooled and liquid salt-cooled fast flexible conversion ratio reactors were developed. Both concepts have cores reated at 2400 MWt placed in a large-pool-type vessel with dual-free level, which also contains four intermediate heat exchanges coupling a primary coolant to a compact and efficient supercritical CO2 Brayton cycle power conversion system. Decay heat is removed passively using an enhanced Reactor Vessel Auxiliary Cooling System and a Passive Secondary Auxiliary Cooling System. The most important findings were that (1) it is feasible to design the lead-cooled and salt-cooled reactor with the flexible conversion ratio (CR) in the range of CR=0 and CR=1 n a manner that achieves inherent reactor shutdown in unprotected accidents, (2) the salt-cooled reactor requires Lithium thermal Expansion Modules to overcme the inherent salt coolant's large positive coolant temperature reactivity coefficient, (3) the preferable salt for fast spectrum high power density cores is NaCl-Kcl-MgCl2 as opposed to fluoride salts due to its better themal-hydraulic and neutronic characteristics, and (4) both reactor, but attain power density 3 times smaller than that of the sodium-cooled reactor.

Neil Todreas; Pavel Hejzlar

2008-06-30

34

Hydraulic system for a ratio change transmission  

DOEpatents

Disclosed is a drive assembly (10) for an electrically powered vehicle (12). The assembly includes a transaxle (16) having a two-speed transmission (40) and a drive axle differential (46) disposed in a unitary housing assembly (38), an oil-cooled prime mover or electric motor (14) for driving the transmission input shaft (42), an adapter assembly (24) for supporting the prime mover on the transaxle housing assembly, and a hydraulic system (172) providing pressurized oil flow for cooling and lubricating the electric motor and transaxle and for operating a clutch (84) and a brake (86) in the transmission to shift between the two-speed ratios of the transmission. The adapter assembly allows the prime mover to be supported in several positions on the transaxle housing. The brake is spring-applied and locks the transmission in its low-speed ratio should the hydraulic system fail. The hydraulic system pump is driven by an electric motor (212) independent of the prime mover and transaxle.

Kalns, Ilmars (Northville, MI)

1981-01-01

35

Multiwavelength Pyrometer Developed for Use at Elevated Temperatures in Aerospace Applications  

NASA Technical Reports Server (NTRS)

Researchers at the NASA Glenn Research Center have developed a unique multiwavelength pyrometer for aerospace applications. It has been shown to be a useful and versatile instrument for measuring the surface temperatures of ceramic zirconia thermal barrier coatings (TBCs) and alumina, even when their emissivity is unknown. The introduction of fiber optics into the pyrometer has greatly increased the ease of using this instrument. Direct comparison of measurements obtained using the pyrometer and thin film thermocouples on a sample provided independent verification of pyrometry temperature measurement. Application of the pyrometer has also included simultaneous surface and bulk temperature measurement in a transparent material, the measurement of combustion gas temperatures in the flames of an atmospheric burner, the measurement of the temperature distribution appearing on a large surface from the recording of just a single radiation spectrum emitted from this nonuniform temperature surface, and the measurement of some optical properties for special aeronautical materials-such as nanostructured layers. The multiwavelength pyrometer temperature is obtained from a radiation spectrum recorded over a broad wavelength region by transforming it into a straight line segment(s) in part or all of the spectral region. The intercept of the line segment(s) with the vertical axis at zero wavelength gives the inverse of the temperature. In a two-color pyrometer, the two data points are also amenable to this analysis to determine the unknown temperature. Implicit in a two-color pyrometer is the assumption of wavelength-independent emissivity. Its two (and minimum) pieces of data are sufficient to determine this straight line. However, a multiwavelength pyrometer not only has improved accuracy but also confirms that the wavelength-independent emissivity assumption is valid when a multitude of data points are shown to lie on a simple straight line.

Ng, Daniel L.

2003-01-01

36

Spectral stray light effect on high-temperature measurements using a near-infrared multi-wavelength pyrometer  

NASA Astrophysics Data System (ADS)

The spectral stray light is a major, non-negligible error source affecting spectral intensity measurements for optical instruments. The purpose of this study is to investigate the effects of spectral stray light on high-temperature measurements using a near-infrared (1.0-1.65 ?m) multi-wavelength pyrometer. The spectral stray light corrections were measured for the multi-wavelength pyrometer using a pulsed tunable laser for wavelengths from 0.41 ?m to 2.63 ?m. A matrix correction method was then used for the spectral stray light for the multi-wavelength pyrometer. The spectral response characteristics of the pyrometer were calibrated using a standard high-temperature blackbody source. The experimental results show that the spectral response characteristics are approximately identical for different calibration temperatures when the spectral stray light correction is used. The corrections for the spectral stray light significantly improve the accuracy of the multi-wavelength pyrometer at a blackbody calibration temperature which gives a simplified accurate calibration procedure, unlike the temperature calibrations for general optical pyrometers. Temperature measurement tests using a multi-wavelength pyrometer for standard high-temperature source further verified the measurement accuracy of the calibrated pyrometer which also illustrates the necessity of the spectral stray light corrections for the complex optical pyrometer and the applicability of the multi-wavelength algorithm.

Fu, Tairan; Duan, Minghao; Liu, Jiangfan; Li, Teng

2014-11-01

37

Use of a variable exposure photographic pyrometer to measure surface temperatures on a hemispherical-face model  

NASA Technical Reports Server (NTRS)

The use of a photographic pyrometer for nonintrusive measurement of high temperature surfaces in a wind tunnel test is described. The advantages of the pyrometer for measuring surfaces whose unique shape makes use of thermocouples difficult are pointed out. The use of computer operated densitometers or optical processors for the data reduction is recommended.

Kantsios, A. G.; Henley, W. C., Jr.; Snow, W. L.

1982-01-01

38

The Period-Ratio and Mass-Ratio Correlation in Extra-Solar Multiple Planetary Systems  

E-print Network

Employing the data from orbital periods and masses of extra-solar planets in 166 multiple planetary systems, the period-ratio and mass-ratio of adjacent planet pairs are studied. The correlation between the period-ratio and mass-ratio is confirmed and found to have a correlation coefficient of 0.5303 with a 99% confidence interval (0.3807, 0.6528). A comparison with the distribution of synthetic samples from a Monte Carlo simulation reveals the imprint of planet-planet interactions on the formation of adjacent planet pairs in multiple planetary systems.

Jiang, Ing-Guey; Hung, Wen-Liang

2015-01-01

39

The period-ratio and mass-ratio correlation in extra-solar multiple planetary systems  

NASA Astrophysics Data System (ADS)

Employing the data from orbital periods and masses of extra-solar planets in 166 multiple planetary systems, the period ratio and mass ratio of adjacent planet pairs are studied. The correlation between the period ratio and mass ratio is confirmed, with a correlation coefficient of 0.5303 with a 99 per cent confidence interval (0.3807, 0.6528). A comparison with the distribution of synthetic samples from a Monte Carlo simulation reveals the imprint of planet-planet interactions on the formation of adjacent planet pairs in multiple planetary systems.

Jiang, Ing-Guey; Yeh, Li-Chin; Hung, Wen-Liang

2015-04-01

40

Multi-channel optical pyrometer for sub-nanosecond temperature measurements at NDCX-I/II  

SciTech Connect

We present a detailed technical description of a fast multi-channel pyrometer designed for warm-dense-matter (WDM) experiments with intense heavy ion beams at the neutralized-drift-compression-experiment linear accelerator (NDCX-I/II) at Lawrence Berkeley National Laboratory (LBNL). The unique features of the described instrument are its sub-nanosecond temporal resolution (100 ps rise-time) and a broad range, 1,500 K - 12,000 K of measurable brightness temperatures in the visible and near-infrared regions of the spectrum. The working scheme, calibration procedure, experimental data obtained with the pyrometer and future applications are presented.

Ni, P.A.; Bieniosek, F.M.; Waldron, W.L.

2011-04-13

41

In-flight particle pyrometer for thermal spray processes. Final report, October 1, 1992--December 31, 1994  

SciTech Connect

The objective of the project was to produce an industrial hardened particle temperature sensor. In general the thermal spray community believes that the particle temperature and velocity prior to impact on the substrate are two of the predominant parameters which effect coating quality. Prior to the full scale prototyping of such an instrument it was necessary to firmly establish the relationship between operating parameters, particle temperature and coating characteristics. It was shown in the first year of this project that the characteristics and consistency of the coatings formed are directly determined by particle velocity and temperature at impact. For the HVOF spray process the authors have also shown that the particle velocity is determined primarily by chamber pressure, while stoichiometry (the ratio of oxygen to fuel) has a minor influence. Hence, particle velocity can be controlled by maintaining the chamber pressure at a set point. Particle temperature, on the other hand is primarily a function of stoichiometry. Therefore particle velocity and temperature can be independently controlled. In the second year (FY-94), an industrial hardened prototype particle temperature sensor (In-flight Particle Pyrometer) was produced. The IPP is a two-color radiation pyrometer incorporating improvements which make the device applicable to the measurement of in-flight temperature of particles over a wide range of operating conditions in thermal spray processes. The device is insensitive to particulate loading (particle feed rate), particle composition, particle size distribution, and provides an ensemble average particle temperature. The sensor head is compact and coupled to the electronics via a fiber optic cable. Fiber optic coupling allows maximum flexibility of deployment while providing isolation of the electronics from electromagnetic interference and the hot, particulate laden environment of a typical spray booth. The device is applicable to all thermal spray processes, including plasma spray, HVOF, twin wire arc, and liquid metal fed processes, as well as other more conventional high temperature processes such as crucible or hearth melting.

NONE

1995-02-20

42

Seven-wavelength pyrometer for determining surface temperature of ablation materials  

NASA Technical Reports Server (NTRS)

Results which were achieved by a seven-wavelength pyrometer last year are reported in this paper. These studies are directed toward the development of a method for determining the real surface temperature of thermal protection materials and for evaluating its emittance under varieties of reentry environment. A description of the data processing method and apparatus is also included.

Yi, H.

1985-01-01

43

Fuel-air ratio controlled carburetion system  

Microsoft Academic Search

An automatic control system is disclosed supplying a fuel-air mixture to an internal combustion engine including a variable-venturi carburetor. Air is fed into the input of the venturi, the air passing through the throat thereof whose effective area is adjusted by a mechanism operated by a servo motor. Fuel is fed into the input of the venturi from a fuel

Abbey

1980-01-01

44

Ratio  

NASA Astrophysics Data System (ADS)

Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.

Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.

2014-12-01

45

Integrating sphere method for determining the effective spectral emissivity of superalloys at high temperatures using a single wavelength pyrometer  

Microsoft Academic Search

A method that employs an integrating sphere and a single- wavelength pyrometer for measuring the spectral effective emissivities of superalloys in the temperature range is described. The spectral effective emissivities for five superalloys, namely MARM-247, MARM-509, CMSX-4, inconel-718, and N-155 were measured. Correcting the pyrometer measurements for the variations in the object emissivity would reduce the uncertainty in the temperature

Sami D. Alaruri; Lisa Bianchini; Andrew Brewington; Terry Jilg; Brad Belcher

1996-01-01

46

Integrating sphere method for determining the effective spectral emissivity of superalloys at high temperatures using a single wavelength pyrometer  

NASA Astrophysics Data System (ADS)

A method that employs an integrating sphere and a single- wavelength pyrometer for measuring the spectral effective emissivities of superalloys in the temperature range is described. The spectral effective emissivities for five superalloys, namely MARM-247, MARM-509, CMSX-4, inconel-718, and N-155 were measured. Correcting the pyrometer measurements for the variations in the object emissivity would reduce the uncertainty in the temperature measurements to < +/- 1 percent.

Alaruri, Sami D.; Bianchini, Lisa; Brewington, Andrew; Jilg, Terry; Belcher, Brad

1996-09-01

47

Methodology on high ratio multiple configuration systems in image sensor  

NASA Astrophysics Data System (ADS)

The method of a multiple configuration on high ratio systems in image sensor is an important subject. In such an experimental configuration, for aim to break through to large ratio multiple configuration systems bottlenecks, achieve the field of continuous transformation, effect system close to the theoretical limit and configuration dexterity, such as the purpose, method in the design of the integrated sensor system process, the core technology of such a system are thoroughly analyzed and the factors important to the compromise. Theory is studied based on the theory of Gaussian optical system error distribution and comprehensive balancing algorithm; Global optimization method, developed at a system design thought and the optimization model. Results solved the MTF matching problem, research and evaluations shows that the zoom ratio of more than one hundred results in system MTF and so on as qualitative criterion to achieve requirements.

Liu, Hua; Ding, Quanxin; Zhou, Liwei

2014-12-01

48

Pyrometer mount for a closed-circuit thermal medium cooled gas turbine  

DOEpatents

A steam-cooled second-stage nozzle segment has an outer band and an outer cover defining a plenum therebetween for receiving cooling steam for flow through the nozzles to the inner band and cover therefor and return flow through the nozzles. To measure the temperature of the buckets of the stage forwardly of the nozzle stage, a pyrometer boss is electron beam-welded in an opening through the outer band and TIG-welded to the outer cover plate. By machining a hole through the boss and seating a linearly extending tube in the boss, a line of sight between a pyrometer mounted on the turbine frame and the buckets is provided whereby the temperature of the buckets can be ascertained. The welding of the boss to the outer band and outer cover enables steam flow through the plenum without leakage, while providing a line of sight through the outer cover and outer band to measure bucket temperature.

Jones, Raymond Joseph (Duanesburg, NY); Kirkpatrick, Francis Lawrence (late of Galway, NY); Burns, James Lee (Schenectady, NY); Fulton, John Robert (Clifton Park, NY)

2002-01-01

49

The Solar System d\\/h Ratio: Observations and Theories  

Microsoft Academic Search

The measured D\\/H ratios in interstellar environments and in the solar system are reviewed. The two extreme D\\/H ratios in solar\\u000a system water - (720±120)×10?6 in clay minerals and (88±11)×10?6 in chondrules, both from LL3 chondritic meteorites - are interpreted as the result of a progressive isotopic exchange in\\u000a the solar nebula between deuterium-rich interstellar water and protosolar H2. According

François Robert; Daniel Gautier; Bérangère Dubrulle

2000-01-01

50

Estimation of the Damping Ratio of the Coupled System Based on the Damping Ratios of Two 1Dof Systems  

Microsoft Academic Search

A number of different structures in industrial facilities are installed on supports. There is the case that the damage occurs by the coupled vibration. The response magnification is obtained from the modal natural frequency and the modal damping ratio of the coupled system in the seismic design. Therefore, the modal natural frequency and the modal damping ratio of the coupled

Tetsuya Watanabe; Akinori Tomoda; Kihachiro Tanaka

2008-01-01

51

Two-Step Calibration of a Multiwavelength Pyrometer for High Temperature Measurement Using a Quartz Lamp  

NASA Technical Reports Server (NTRS)

There is no theoretical upper temperature limit for pyrometer application in temperature measurements. NASA Glenn's multiwavelength pyrometer can make measurements over wide temperature ranges. However, the radiation spectral response of the pyrometer's detector must be calibrated before any temperature measurement is attempted, and it is recommended that calibration be done at temperatures close to those for which measurements will be made. Calibration is a determination of the constants of proportionality at all wavelengths between the detector's output (voltage) and its input signals (usually from a blackbody radiation source) in order to convert detector output into radiation intensity. To measure high temperatures, the detectors are chosen to be sensitive in the spectral range from 0.4 to 2.5 micrometers. A blackbody furnace equilibrated at around 1000 C is often used for this calibration. Though the detector may respond sensitively to short wavelengths radiation, a blackbody furnace at 1000 C emits only feebly at very short wavelengths. As a consequence, the calibration constants that result may not be the most accurate. For pyrometry calibration, a radiation source emitting strongly at the short wavelengths is preferred. We have chosen a quartz halogen lamp for this purpose.

Ng, Daniel

2001-01-01

52

Temperature measurement involving nanostructured thermal barrier coating using a multiwavelength pyrometer  

NASA Technical Reports Server (NTRS)

It has been reported that erroneous results were obtained when a conventional pyrometer was used to measure the surface temperature of turbine engine components. Temperatures discrepancies were observed in components which were identical, except that one had its measured surface covered by a nanostructured thermal barrier coating (TBC) whereas the other component's surface was not so coated. These components were placed in an identical environment, receiving identical heat fluxes. A pyrometer measured the TBC covered surface hundreds degrees lower. These coatings were about 25 (mu)m thick, consisting of hundreds of layers of finer structures. The TBC's had very low thermal conductivity, heat flux calculations indicated that the temperatures of the coated surface should exhibit much higher temperature than the uncoated surface. Because these coatings were transparent to radiation from the visible to the infrared region, the temperatures measured by the pyrometer should be the temperature of the covered surface. Turbo components' performance and service life depend critically on the temperatures that it would experience; it is therefore important to know accurately and confidently the real surface temperature. Out of these concerns, an investigation into the measurement of nanostructured material surface temperature was carried out.

Ng, Daniel

1996-01-01

53

Evaluation and improvement in the accuracy of a charge-coupled-device-based pyrometer for temperature field measurements of continuous casting billets.  

PubMed

This paper presents a radiometric high-temperature field measurement model based on a charge-coupled-device (CCD). According to the model, an intelligent CCD pyrometer with a digital signal processor as the core is developed and its non-uniformity correction algorithm for reducing the differences in accuracy between individual pixel sensors is established. By means of self-adaptive adjustment for the light-integration time, the dynamic range of the CCD is extended and its accuracy in low-temperature range is improved. The non-uniformity correction algorithm effectively reduces the accuracy differences between different pixel sensors. The performance of the system is evaluated through a blackbody furnace and an integrating sphere, the results of which show that the dynamic range of 400 K is obtained and the accuracy in low temperature range is increased by 7 times compared with the traditional method based on the fixed light-integration time. In addition, the differences of accuracy between the on-axis pixel and the most peripheral pixels are decreased from 19.1 K to 2.8 K. Therefore, this CCD pyrometer ensures that the measuring results of all pixels tend to be equal-accuracy distribution across the entire measuring ranges. This pyrometric system has been successfully applied to the temperature field measurements in continuous casting billets. PMID:23822369

Bai, Haicheng; Xie, Zhi; Zhang, Yuzhong; Hu, Zhenwei

2013-06-01

54

The distribution of period ratios in Kepler planetary systems  

NASA Astrophysics Data System (ADS)

Kepler's multi-planet systems are a valuable tool to understand the architectures and dynamics of the inner parts of planetary systems. I present an analysis of the distribution of orbital period ratios from candidate systems identified in the Quarter 8 catalog (Burke et al. 2014). This distribution is corrected for the effects of geometric transit probabilities and the completeness of the data reduction pipeline. We find that the distribution of period ratios falls as a power law with exponent -1.26 ± 0.05. We also identify a new, statistically significant feature near a period ratio of 2.2. These observations may provide insights into the formation and evolution of these systems.

Steffen, Jason H.; Hwang, Jason A.

2015-01-01

55

System and method for high precision isotope ratio destructive analysis  

DOEpatents

A system and process are disclosed that provide high accuracy and high precision destructive analysis measurements for isotope ratio determination of relative isotope abundance distributions in liquids, solids, and particulate samples. The invention utilizes a collinear probe beam to interrogate a laser ablated plume. This invention provides enhanced single-shot detection sensitivity approaching the femtogram range, and isotope ratios that can be determined at approximately 1% or better precision and accuracy (relative standard deviation).

Bushaw, Bruce A; Anheier, Norman C; Phillips, Jon R

2013-07-02

56

The period ratio distribution of Kepler's candidate multiplanet systems  

NASA Astrophysics Data System (ADS)

We calculate and analyse the distribution of period ratios observed in systems of Kepler exoplanet candidates including studies of both adjacent planet pairs and all planet pairs. These distributions account for both the geometrical bias against detecting more distant planets and the effects of incompleteness due to planets missed by the data reduction pipeline. In addition to some of the known features near first-order mean-motion resonances (MMRs), there is a significant excess of planet pairs with period ratios near 2.2. The statistical significance of this feature is assessed using Monte Carlo simulation. We also investigate the distribution of period ratios near first-order MMR and compare different quantities used to measure this distribution. We find that beyond period ratios of ˜2.5, the distribution of all period ratios follows a power law with an exponent -1.26 ± 0.05. We discuss implications that these results may have on the formation and dynamical evolution of Kepler-like planetary systems-systems of sub-Neptune/super-Earth planets with relatively short orbital periods.

Steffen, Jason H.; Hwang, Jason A.

2015-04-01

57

DETECTION OF LOW-MASS-RATIO STELLAR BINARY SYSTEMS  

SciTech Connect

O- and B-type stars are often found in binary systems, but the low binary mass-ratio regime is relatively unexplored due to observational difficulties. Binary systems with low mass ratios may have formed through fragmentation of the circumstellar disk rather than molecular cloud core fragmentation. We describe a new technique sensitive to G- and K-type companions to early B stars, a mass ratio of roughly 0.1, using high-resolution, high signal-to-noise spectra. We apply this technique to a sample of archived VLT/CRIRES observations of nearby B stars in the CO bandhead near 2300 nm. While there are no unambiguous binary detections in our sample, we identify HIP 92855 and HIP 26713 as binary candidates warranting follow-up observations. We use our non-detections to determine upper limits to the frequency of FGK stars orbiting early B-type primaries.

Gullikson, Kevin; Dodson-Robinson, Sarah [Astronomy Department, University of Texas, 1 University Station C1400, Austin, TX 78712 (United States)

2013-01-01

58

Electronic control system for air fuel ratio compensation in highlands  

Microsoft Academic Search

An electronic control system which electronically controls the air fuel ratio of a mixture being supplied to a gasoline engine in highlands is described. An orifice device is provided in a passage through which secondary air is supplied to the venturi section of the engine carburetor. An electronic control unit carries out programmed control of the orifice opening of the

J. Kimura; A. Noji

1981-01-01

59

Design and fabrication of an infrared optical pyrometer ASIC as a diagnostic for shock physics experiments  

NASA Astrophysics Data System (ADS)

Optical pyrometry is the sensing of thermal radiation emitted from an object using a photoconductive device to convert photons into electrons, and is an important diagnostic tool in shock physics experiments. Data obtained from an optical pyrometer can be used to generate a blackbody curve of the material prior to and after being shocked by a high speed projectile. The sensing element consists of an InGaAs photodiode array, biasing circuitry, and multiple transimpedance amplifiers to boost the weak photocurrent from the noisy dark current into a signal that can eventually be digitized. Once the circuit elements have been defined, more often than not commercial-off-the-shelf (COTS) components are inadequate to satisfy every requirement for the diagnostic, and therefore a custom application specific design has to be considered. This thesis outlines the initial challenges with integrating the photodiode array block with multiple COTS transimpedance amplifiers onto a single chip, and offers a solution to a comparable optical pyrometer that uses the same type of photodiodes in conjunction with a re-designed transimpedance amplifier integrated onto a single chip. The final design includes a thorough analysis of the transimpedance amplifier along with modeling the circuit behavior which entails schematics, simulations, and layout. An alternative circuit is also investigated that incorporates an approach to multiplex the signals from each photodiode onto one data line and not only increases the viable real estate on the chip, but also improves the behavior of the photodiodes as they are subjected to less thermal load. The optical pyrometer application specific integrated circuit (ASIC) for shock physic experiments includes a transimpedance amplifier (TIA) with a 100 k? gain operating at bandwidth of 30 MHz, and an input-referred noise RMS current of 50 nA that is capable of driving a 50 ? load.

Gordon, Jared

60

Stability of orbits near large mass ratio binary systems  

NASA Astrophysics Data System (ADS)

With improved observational capabilities and techniques, an increasing number of exoplanets have been discovered to orbit in the vicinity of binary star systems. In this investigation, periodic motions near a large mass ratio binary are explored within the context of the circular restricted three-body problem. Specifically, stability analysis is used to explore the effect of the mass ratio on the structure of families of periodic orbits. Such analysis is useful in a variety of applications, including the determination of potentially stable exoplanet motions near a binary star.

Bosanac, Natasha; Howell, Kathleen C.; Fischbach, Ephraim

2015-02-01

61

Remote Heat Flux Using a Self Calibration Multiwavelength Pyrometer and a Transparent Material  

NASA Technical Reports Server (NTRS)

A self calibrating multiwavelength pyrometer was used to conduct remote heat flux measurements using a transparent sapphire disk by determining the sapphire disk's front and back surface temperatures. Front surface temperature (Tfs) was obtained from detection of surface emitted radiation at long wavelengths (k = 6 gm). Back surface temperature (Tbs) was obtained from short wavelength (1 to 5 gm) radiation transmitted through the sapphire disk. The thermal conductivity of the sapphire disk and the heat transfer coefficients h, and h2 of its surfaces are determined experimentally. An analysis of the heat flux measurement is presented.

Ng, Daniel

1998-01-01

62

Remote Heat Flux Measurement Using a Self Calibration Multiwavelength Pyrometer and a Transparent Material  

NASA Technical Reports Server (NTRS)

A self calibrating multiwavelength pyrometer was used to conduct remote heat flux measurements using a transparent sapphire disk by determining the sapphire disk's front and back surface temperatures. Front surface temperature (Tfs) was obtained from detection of surface emitted radiation at long wavelengths (lambda > 6 micrometers). Back surface temperature (Tbs) was obtained from short wavelength (1 to 5 micrometers) radiation transmitted through the sapphire disk. The thermal conductivity k of the sapphire disk and the heat transfer coefficients h(sub 1) and h(sub 2) of its surfaces are determined experimentally. An analysis of the heat flux measurement is presented.

Ng, Daniel

1998-01-01

63

21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.  

Code of Federal Regulations, 2014 CFR

...Lecithin/sphingomyelin ratio in amniotic fluid test system. 862.1455 Section 862...Lecithin/sphingomyelin ratio in amniotic fluid test system. (a) Identification. A lecithin/sphingomyelin ratio in amniotic fluid test system is a device intended to...

2014-04-01

64

21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.  

Code of Federal Regulations, 2010 CFR

...Lecithin/sphingomyelin ratio in amniotic fluid test system. 862.1455 Section 862...Lecithin/sphingomyelin ratio in amniotic fluid test system. (a) Identification. A lecithin/sphingomyelin ratio in amniotic fluid test system is a device intended to...

2010-04-01

65

21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.  

Code of Federal Regulations, 2011 CFR

...Lecithin/sphingomyelin ratio in amniotic fluid test system. 862.1455 Section 862...Lecithin/sphingomyelin ratio in amniotic fluid test system. (a) Identification. A lecithin/sphingomyelin ratio in amniotic fluid test system is a device intended to...

2011-04-01

66

21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.  

Code of Federal Regulations, 2013 CFR

...Lecithin/sphingomyelin ratio in amniotic fluid test system. 862.1455 Section 862...Lecithin/sphingomyelin ratio in amniotic fluid test system. (a) Identification. A lecithin/sphingomyelin ratio in amniotic fluid test system is a device intended to...

2013-04-01

67

21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.  

Code of Federal Regulations, 2012 CFR

...Lecithin/sphingomyelin ratio in amniotic fluid test system. 862.1455 Section 862...Lecithin/sphingomyelin ratio in amniotic fluid test system. (a) Identification. A lecithin/sphingomyelin ratio in amniotic fluid test system is a device intended to...

2012-04-01

68

An evaluation of ratio systems in radioecological studies  

SciTech Connect

Replicate samples of soil, Juncus squarrosus and Calluna vulgaris were taken within a grid system on an organic peatland soil site in Ireland. A similar sampling survey was carried out on an organic rich forest soil site in Sweden, where Vaccinium myrtillus and Vaccinium vitis-idaea with corresponding soil samples were taken within a Picea abies stand. The data were used to investigate the relationship between soil and plant {sup 137}Cs content and to examine the validity of using ratios to describe this relationship. Findings from both countries were in agreement. There were no significant changes in plant {sup 137}Cs concentration associated with increasing soil content. When data from both countries were merged and treated as a single data set, a significant overall positive correlation (95% confidence level) between soil and plant {sup 137}Cs levels was observed. Concentration ratios and transfer factors were calculated for {sup 137}Cs and {sup 40}K uptake from soils to plants. Both ratio types exhibited a clearly defined decrease associated with increasing soil concentrations for both radionuclides. Findings demonstrate serious problems with the use of ratios for the evaluation of radionuclide transfer. 28 refs., 4 figs., 10 tabs.

McGee, E.J.; Synnott, H.J.; Colgan, P.A. [Radiological Protection Institute of Ireland, Dublin (Ireland)] [and others

1996-02-01

69

Dilution Ratios for HB Line Phase I Eductor System  

SciTech Connect

HB Line Phase I product transfer includes an eductor which transfers liquid from Product Hold Tank (PHT) RT-33 or RT-34 to Tank 11.1. The eductor also dilutes the liquid from the PHT with eductant. Dilution must be reliably controlled because of criticality concerns with H Canyon Tanks. The eductor system, which contains a 1 inch Model 264 Schutte and Koerting eductor, was previously modeled [1] in 1998 and dilution ratios were calculated for different flow restrictors, eductant pressures and densities for the eductant and the contents of the PHT. The previous calculation was performed using spreadsheet software no longer supported at SRS. For the previous work dilution ratio was defined as the volume of eductant consumed divided by volume of PHT contents transferred. Since 1998 HB Line Engineering has changed the definition of dilution ratio to the total volume of liquid, eductant consumed plus the volume of PHT liquid transferred, divided by the volume of PHT liquid transferred. The 1998 base case calculation was for a restrictor diameter of 0.334 inches, an eductant supply pressure of 15 psig, full PHT, an eductant specific gravity of 1.385 and a PHT density of 1.015. The base case dilution ratio calculated in 1998 using the current definition was 3.52. After accounting for uncertainty the minimum dilution ratio decreased to 3.23. In 2001 HB Line Engineering requested that the calculation be repeated for a manganous nitrate solution eductant and also a process water eductant. The other conditions were the same as for the 1998 calculation. The objective of this report is to document the calculations and the results.

Steimke, J.L.

2002-01-31

70

[Development of multi-target multi-spectral high-speed pyrometer].  

PubMed

The plume temperature of a solid propellant rocket engine (SPRE) is a fundamental parameter in denoting combustion status. It is necessary to measure the temperature along both the axis and the radius of the engine. In order to measure the plume temperature distribution of a solid propellant rocket engine, the multi-spectral thermometry has been approved. Previously the pyrometer was developed in the Harbin Institute of Technology of China in 1999, which completed the measurement of SPRE plume temperature and its distribution with multi-spectral technique in aerospace model development for the first time. Following this experience, a new type of multi-target multi-spectral high-speed pyrometer used in the ground experiments of SPRE plume temperature measurement was developed. The main features of the instrument include the use of a dispersing prism and a photo-diode array to cover the entire spectral band of 0.4 to 1.1 microm. The optic fibers are used in order to collect and transmit the thermal radiation fluxes. The instrument can measure simultaneously the temperature and emissivity of eight spectra for six uniformly distributed points on the target surface, which are well defined by the hole on the field stop lens. A specially designed S/H (Sample/Hold) circuit, with 48 sample and hold units that were triggered with a signal, measures the multi-spectral and multi-target outputs. It can sample 48 signals with a less than 10ns time difference which is most important for the temperature calculation. PMID:19271529

Xiao, Peng; Dai, Jing-Min; Wang, Qing-Wei

2008-11-01

71

Effective spectral emissivity measurements of superalloys and YSZ thermal barrier coating at high temperatures using a 1.6?m single wavelength pyrometer  

Microsoft Academic Search

A method which employs an integrating sphere and a single-wavelength (1.6?m) pyrometer for measuring the spectral effective emissivities of superalloys in the temperature range (=650–1050°C) is described. The spectral effective emissivities for five superalloys, namely, MARM-247, MARM-509, CMSX-4, Inconel-718, N-155 and two René-N6 samples coated with YSZ thermal barrier coating were measured. Correcting the pyrometer measurements for the variations in

Sami Alaruri; Lisa Bianchini; Andrew Brewington

1998-01-01

72

Pitch attitude stabilization system utilizing engine pressure ratio feedback signals  

NASA Technical Reports Server (NTRS)

The changes in the engine pressure ratio signals which result from thrust changes are used to generate a pitch stabilization signal. The signal is combined with other pitch control signals to automatically counteract pitching moments resulting from the changes in engine thrust.

Kelley, W. W. (inventor)

1981-01-01

73

Control system and method for a power delivery system having a continuously variable ratio transmission  

DOEpatents

A control system and method for a power delivery system, such as in an automotive vehicle, having an engine coupled to a continuously variable ratio transmission (CVT). Totally independent control of engine and transmission enable the engine to precisely follow a desired operating characteristic, such as the ideal operating line for minimum fuel consumption. CVT ratio is controlled as a function of commanded power or torque and measured load, while engine fuel requirements (e.g., throttle position) are strictly a function of measured engine speed. Fuel requirements are therefore precisely adjusted in accordance with the ideal characteristic for any load placed on the engine.

Frank, Andrew A. (1034 Hillside Ave., Madison, WI 53705)

1984-01-01

74

Control system and method for a power delivery system having a continuously variable ratio transmission  

DOEpatents

A control system and method for a power delivery system, such as in an automotive vehicle, having an engine coupled to a continuously variable ratio transmission (CVT). Totally independent control of engine and transmission enable the engine to precisely follow a desired operating characteristic, such as the ideal operating line for minimum fuel consumption. CVT ratio is controlled as a function of commanded power or torque and measured load, while engine fuel requirements (e.g., throttle position) are strictly a function of measured engine speed. Fuel requirements are therefore precisely adjusted in accordance with the ideal characteristic for any load placed on the engine. 4 figs.

Frank, A.A.

1984-07-10

75

Surface heat flux data from energy balance Bowen ratio systems  

SciTech Connect

The 350 {times} 400 km domain of the Atmospheric Radiation Measurement (ARM) Program`s Clouds and Radiation Testbed (CART) site in the southern Great Plains is equipped with 10 energy balance Bowen ratio (EBBR) stations at grassland sites; they measure the net radiation, ground heat flux, and temperature/humidity differences between 1.0 and 2.0 m heights. The latter differences provide estimates of the geometric Bowen ratio ({beta}), which are used to estimate sensible and latent heat fluxes. This paper addresses the problem that occurs when the value of {beta} is near {minus}1 and to demonstrate the effectiveness of the EBBR stations in collecting energy flux data at the CART site.

Wesely, M.L.; Cook, D.R.; Coulter, R.L.

1995-06-01

76

Primary Radiometry for the mise-en-pratique: The Laser-Based Radiance Method Applied to a Pyrometer  

NASA Astrophysics Data System (ADS)

A new setup has been implemented at LCM-LNE-CNAM for the determination "of the spectral responsivity of radiation thermometers for the determination" of the thermodynamic temperature of high-temperature blackbodies at the temperature of a metal-carbon eutectic phase transition. In this new setup, an innovative acoustic-optic modulator feedback loop is used to stabilize the radiance of a wavelength tunable laser. The effect of residual optical interferences on the calibration of a test pyrometer is analyzed. The full uncertainty budget is presented.

Briaudeau, S.; Sadli, M.; Bourson, F.; Rougi, B.; Rihan, A.; Zondy, J.-J.

2011-12-01

77

Dynamic Modeling of Hydraulic Power Steering System with Variable Ratio Rack and Pinion Gear  

Microsoft Academic Search

A comprehensive mathematical model of a typical hydraulic power steering system equipped with variable ratio rack and pinion gear is developed. The steering system's dynamic characteristics are investigated and its forced vibrations are compared with those obtained from a counterpart system with a constant ratio rack and pinion gear. The modeling details of the mechanism subsystem, hydraulic supply lines subsystem

Nong Zhang; Miao Wang

2005-01-01

78

Temperature Measurement of a Miniature Ceramic Heater in the Presence of an Extended Interfering Background Radiation Source Using a Multiwavelength Pyrometer  

NASA Technical Reports Server (NTRS)

Temperature measurement of small (millimeter size) objects is generally difficult and demanding. Measurement involving ceramic materials using the traditional one- and two-color pyrometer is difficult because of their complex optical properties, such as low emissivity which may vary with both temperature and wavelength. Pyrometry applications in an environment with an interfering radiation source of extended dimension adds extra complexity to the process. We show that the multiwavelength pyrometer successfully measured the temperatures of a millimeter (mm) size ceramic heater under these demanding conditions.

Ng, Daniel

1999-01-01

79

Effective spectral emissivity measurements of superalloys and YSZ thermal barrier coating at high temperatures using a 1.6?m single wavelength pyrometer  

NASA Astrophysics Data System (ADS)

A method which employs an integrating sphere and a single-wavelength (1.6 ?m) pyrometer for measuring the spectral effective emissivities of superalloys in the temperature range (=650-1050°C) is described. The spectral effective emissivities for five superalloys, namely, MARM-247, MARM-509, CMSX-4, Inconel-718, N-155 and two René-N6 samples coated with YSZ thermal barrier coating were measured. Correcting the pyrometer measurements for the variations in the object emissivity would reduce the uncertainty in the temperature measurements to <±1%.

Alaruri, Sami; Bianchini, Lisa; Brewington, Andrew

1998-07-01

80

Dilution Ratios for HB Line Phase I Eductor System  

Microsoft Academic Search

HB Line Phase I product transfer includes an eductor which transfers liquid from Product Hold Tank (PHT) RT-33 or RT-34 to Tank 11.1. The eductor also dilutes the liquid from the PHT with eductant. Dilution must be reliably controlled because of criticality concerns with H Canyon Tanks. The eductor system, which contains a 1 inch Model 264 Schutte and Koerting

Steimke

2002-01-01

81

Error performance of preamplified optical PPM systems with finite extinction ratios  

NASA Astrophysics Data System (ADS)

In this paper, we present an analytical study of the error performance in optically preamplified, M-ary pulse position modulation, in free-space optical communication systems with finite extinction ratios. We derive a theoretical expression for the probability of bit error and compute it numerically for different symbol sizes and extinction ratios. We also provide the power penalty due to a finite extinction ratio for both coded and uncoded systems. The study shows that, in certain cases and for a given extinction ratio, lower symbol sizes may yield an error performance similar to that achieved by higher symbol sizes.

Landolsi, Taha; Elrefaie, Aly F.

2014-08-01

82

Global qualitative analysis of a ratio-dependent predator–prey system  

Microsoft Academic Search

.  ?Ratio-dependent predator–prey models are favored by many animal ecologists recently as more suitable ones for predator–prey\\u000a interactions where predation involves searching process. However, such models are not well studied in the sense that most\\u000a results are local stability related. In this paper, we consider the global behaviors of solutions of a ratio-dependent predator–prey\\u000a systems. Specifically, we shall show that ratio

Yang Kuang; Edoardo Beretta

1998-01-01

83

Mortality, fertility, and the OY ratio in a model hunter-gatherer system.  

PubMed

An agent-based model (ABM) is used to explore how the ratio of old to young adults (the OY ratio) in a sample of dead individuals is related to aspects of mortality, fertility, and longevity experienced by the living population from which the sample was drawn. The ABM features representations of rules, behaviors, and constraints that affect person- and household-level decisions about marriage, reproduction, and infant mortality in hunter-gatherer systems. The demographic characteristics of the larger model system emerge through human-level interactions playing out in the context of "global" parameters that can be adjusted to produce a range of mortality and fertility conditions. Model data show a relationship between the OY ratios of living populations (the living OY ratio) and assemblages of dead individuals drawn from those populations (the dead OY ratio) that is consistent with that from empirically known ethnographic hunter-gatherer cases. The dead OY ratio is clearly related to the mean ages, mean adult mortality rates, and mean total fertility rates experienced by living populations in the model. Sample size exerts a strong effect on the accuracy with which the calculated dead OY ratio reflects the actual dead OY ratio of the complete assemblage. These results demonstrate that the dead OY ratio is a potentially useful metric for paleodemographic analysis of changes in mortality and mean age, and suggest that, in general, hunter-gatherer populations with higher mortality, higher fertility, and lower mean ages are characterized by lower dead OY ratios. PMID:24523247

White, Andrew A

2014-06-01

84

A sex-ratio Meiotic Drive System in Drosophila simulans. II: An X-linked Distorter  

E-print Network

the evolutionary forces shaping the meiotic behavior of the sex chromosomes. Here we characterize a sexA sex-ratio Meiotic Drive System in Drosophila simulans. II: An X-linked Distorter Yun Tao1 of heteromorphic sex chromosomes creates a genetic condition favoring the invasion of sex-ratio meiotic drive

Hartl, Daniel L.

85

System and rapidity dependence of baryon to meson ratios at RHIC  

E-print Network

The rapidity and centrality dependence of baryon to meson ratios in Au$+$Au, Cu$+$Cu and p$+$p collisions at $\\sqrt{s_{NN}}$ = 200 GeV at RHIC is presented. The $\\bar{p}/\\pi^{-}$ ratios are founded to be independent of collision system at a fixed $$ at mid- and forward rapidities.

Eun-Joo Kim

2005-10-03

86

The effect of metallicity on the minimum mass ratio of W Ursae Majoris-type systems  

Microsoft Academic Search

According to the prevenient theoretical study, the minimum mass ratio for tidal stability of W Ursae Majoris (W UMa) systems\\u000a is q\\u000a min?=(M\\u000a 2\\/M\\u000a 1)?0.071–0.078. However, the mass ratios of some observed W UMa binaries are smaller than the theoretical minimum mass ratio.\\u000a Using Eggleton’s stellar evolution code, we study the effects of metallicity and evolution on the minimum mass ratio of

Dengkai Jiang; Zhanwen Han; Cheng Liu; Jiancheng Wang; Lifang Li

2010-01-01

87

Peak-to-Average Power Ratio (PAR) reduction for acoustic OFDM systems  

E-print Network

A major drawback of orthogonal frequency division multiplexing (OFDM) is its large peak-to-average power ratio (PAR). Techniques for PAR reduction have been extensively studied for radio communication systems. While these ...

Rojo Garrave, Guillem

88

High contrast ratio and compact-sized prism for DLP projection system.  

PubMed

In this paper, a novel light separator with contrast ratio enhancement but maintaining the optical efficiency of the DLP projection system is proposed. The main capability of the novel light separator is to direct the uncontrolled light away from the image system. The working theorem for the novel light separator is derived as well. Uncontrolled light is kept away from the image system by a total internal reflection surface, thereby effectively improving the image quality. Compared with the conventional contrast ratio enhancement method, the FO:FO contrast ratio can be improved from 839:1 to 48250:1, the ANSI contrast ratio can be improved from 180:1 to 306:1, while the image system efficiency remains at 76.2%. PMID:25090516

Huang, Yung-Chih; Pan, Jui-Wen

2014-07-14

89

A trading-ratio system for trading water pollution discharge permits  

Microsoft Academic Search

The fact that water flows to the lowest level uni-directionally is a very specific and useful property of water. By utilizing this property, we design a trading-ratio system (TRS) of tradable discharge permits for water pollution control. Such a trading-ratio system has three main characteristics: (1) the zonal effluent cap is set by taking into account the water pollutant loads

Ming-Feng Hung; Daigee Shaw

2005-01-01

90

Peak-to-average power ratio (PAR) reduction for acoustic OFDM systems  

Microsoft Academic Search

A major drawback of orthogonal frequency division multiplexing (OFDM) is its large peak-to-average power ratio (PAR). Techniques for PAR reduction have been extensively studied for radio communication systems. While these techniques are applicable to acoustic systems, we take a different approach that aims to capitalize on the fundamental differences between the acoustic and radio systems, namely the fact that acoustic

Guillem Rojo; Milica Stojanovic

2009-01-01

91

Performance of the Bowen ratio systems on a 22 deg slope  

NASA Technical Reports Server (NTRS)

The Bowen ratio energy balance technique was used to assess the energy fluxes on inclined surfaces during the First ISLSCP Field Experiment (FIFE). Since air flow over sloping surface may differ from that over flat terrain, it is important to examine whether Bowen ratio measurements taken on sloping surfaces are valid. In this study, the suitability of using the Bowen ratio technique on sloping surfaces was tested by examining the assumptions that the technique requires for valid measurements. This was accomplished by studying the variation of Bowen ratio measurements along a selected slope at the FIFE site. In September 1988, four Bowen ratio systems were set up in a line along the 22 degree north-facing slope with northerly air flow (wind went up the slope). In July of 1989, six Bowen ratio systems were similarly installed with southerly air flow (the wind went down slope). Results indicated that, at distances between 10 to 40 meters from the top of the slope, no temperature or vapor pressure gradient parallel to the slope was detected. Uniform Bowen ratio values were obtained on the slope, and thus the sensible or latent heat flux should be similar along the slope. This indicates that the assumptions for valid flux measurements are reasonably met at the slope. The Bowen ratio technique should give the best estimates of the energy fluxes on slopes similar to that in this study.

Nie, D.; Flitcroft, I.; Kanemasu, E. T.

1990-01-01

92

Dynamic Modeling of Hydraulic Power Steering System with Variable Ratio Rack and Pinion Gear  

NASA Astrophysics Data System (ADS)

A comprehensive mathematical model of a typical hydraulic power steering system equipped with variable ratio rack and pinion gear is developed. The steering system’s dynamic characteristics are investigated and its forced vibrations are compared with those obtained from a counterpart system with a constant ratio rack and pinion gear. The modeling details of the mechanism subsystem, hydraulic supply lines subsystem and the rotary spool valve subsystem are provided and included in the integrated steering system model. The numerical simulations are conducted to investigate the dynamics of the nonlinear parametric steering system. From the comparison between simulated results and the experimental ones, it is shown that the model accurately integrates the boost characteristics of the rotary spool valve which is the key component of hydraulic power steering system. The variable ratio rack-pinion gear behaviors significantly differently from its constant ratio counterpart does. It significantly affects not only the system natural frequencies but also reduces vibrations under constant rate and ramp torque steering inputs. The developed steering model produces valid predictions of the system’s behavior and therfore could assist engineers in the design and analysis of integrated steering systems.

Zhang, Nong; Wang, Miao

93

Optimized signal to noise ratio of a PMT based detector system in Mie-Lidar  

Microsoft Academic Search

Signal to noise ratio calculations are made for a Mie-Lidar system which uses photomultiplier tube (PMT) as a detector. Power received by the Lidar system from different altitudes is calculated considering four different model vertical profiles of aerosols representing urban and background continent conditions, with and without stratospheric volcanic aerosol layer. The minimum detectable energy of the backscattered laser pulse

Y. B. Acharya; A. Jayaraman

2006-01-01

94

The analysis of signal-to-noise ratio of airborne LIDAR system under state of motion  

Microsoft Academic Search

This article gives an overview of airborne LIDAR (laser light detection and ranging) system and its application. By analyzing the transmission and reception process of laser signal, the article constructs a model of echo signal of the LIDAR system, and gives some basic formulas which make up the relationship of signal-to-noise ratio, for example, the received power, the dark noise

Huang Hao; Tian Lan; Yingchao Zhang; Guoqiang Ni

2010-01-01

95

Effect of sex ratio on the immune system of Oreochromis mossambicus (Peters)  

Microsoft Academic Search

The social environment of fish has a crucial role to play on the immune system and hence on the overall health status. Stressors of social origin such as dominance, subordination, and fight for mate have a major impact on the immune system of fish. The present study was designed with the objective of finding the effect of sex ratio of

C. Binuramesh; M. Prabakaran; Dieter Steinhagen; R. Dinakaran Michael

2006-01-01

96

The Determination of Heat Capacity Ratios in a Simple Open System  

ERIC Educational Resources Information Center

A virtually closed system is treated as open and compared to known results. The classic experiment of Clement and Desormes provides the conceptual framework for this open system approach in determining the molar heat capacity ratios, lambda. This alternate view, extends the theoretical treatment beyond the first law of thermodynamics for closed…

Holden, Glen L.

2007-01-01

97

On the modal damping ratios of shear-type structures equipped with Rayleigh damping systems  

Microsoft Academic Search

The effects of added manufactured viscous dampers upon shear-type structures are analytically investigated here for the class of Rayleigh damping systems. The definitions of mass proportional damping (MPD) and stiffness proportional damping (SPD) systems are briefly recalled and their physical counterpart is derived. From basic physics, a detailed mathematical demonstration that the first modal damping ratio of a structure equipped

T. Trombetti; S. Silvestri

2006-01-01

98

On the Planetary Orbital Period Ratio Distribution In Multiple Planet Systems  

NASA Astrophysics Data System (ADS)

Many multiple planet systems have been found by both radial velocity (RV) and transit surveys, such as the Kepler mission. Period ratio distribution of these planet candidates show that they do not prefer to be in or near Mean Motion Resonance (MMR). Nevertheless, there are small but significant excesses of candidate pairs both spaced slightly exterior to exact resonance, particular near the first order of MMR, such as 2:1 and 3:2. Here, we first review recent observational constraints on these multiple transiting systems and theoretical models, which attempt to understand their period ratio distributions. Then we identify a statistical effect based on an intrinsic asymmetry associated with MMR, and find it play an important role in shaping the period ratio distribution near MMR. Last but least, we also find such an intrinsic asymmetry is existing in asteroids of our solar system.

Xie, Ji-Wei

2014-04-01

99

Disturbance rejection performance analyses of closed loop control systems by reference to disturbance ratio.  

PubMed

This study investigates disturbance rejection capacity of closed loop control systems by means of reference to disturbance ratio (RDR). The RDR analysis calculates the ratio of reference signal energy to disturbance signal energy at the system output and provides a quantitative evaluation of disturbance rejection performance of control systems on the bases of communication channel limitations. Essentially, RDR provides a straightforward analytical method for the comparison and improvement of implicit disturbance rejection capacity of closed loop control systems. Theoretical analyses demonstrate us that RDR of the negative feedback closed loop control systems are determined by energy spectral density of controller transfer function. In this manner, authors derived design criteria for specifications of disturbance rejection performances of PID and fractional order PID (FOPID) controller structures. RDR spectra are calculated for investigation of frequency dependence of disturbance rejection capacity and spectral RDR analyses are carried out for PID and FOPID controllers. For the validation of theoretical results, simulation examples are presented. PMID:25311160

Alagoz, Baris Baykant; Deniz, Furkan Nur; Keles, Cemal; Tan, Nusret

2015-03-01

100

The analysis of signal-to-noise ratio of airborne LIDAR system under state of motion  

NASA Astrophysics Data System (ADS)

This article gives an overview of airborne LIDAR (laser light detection and ranging) system and its application. By analyzing the transmission and reception process of laser signal, the article constructs a model of echo signal of the LIDAR system, and gives some basic formulas which make up the relationship of signal-to-noise ratio, for example, the received power, the dark noise power and so on. And this article carefully studies and analyzes the impact of some important parameters in the equation on the signal-to-noise ratio, such as the atmospheric transmittance coefficient, the work distance. And the matlab software is used to simulate the detection environment, and obtains a series values of signal-to-noise (SNR) ratio under different circumstances such as sunny day, cloudy day, day, night. And the figures which describe how the SNR of LIDAR system is influenced by the critical factors are shown in the article. Finally according to the series values of signal-to-noise ratio and the figures, the SNR of LIDAR system decreases as the distance increases, and the atmospheric transmittance coefficient caused by bad weather, and also high work temperature drops the SNR. Depending on these conclusions, the LIDAR system will work even better.

Hao, Huang; Lan, Tian; Zhang, Yingchao; Ni, Guoqiang

2010-11-01

101

A gas chromatography/combustion/isotope ratio mass spectrometry system for high-precision  

E-print Network

A gas chromatography/combustion/isotope ratio mass spectrometry system for high-precision d13 C methane cycle in the past. We developed a highly automated (continuous-flow) gas chromatography in the infrared spectrum. Today methane is recognised as an important greenhouse gas that affects the earth

Fischer, Hubertus

102

Peak-to-Average Power-Ratio Reduction Algorithms for OFDM Systems via Constellation Extension  

E-print Network

Peak-to-Average Power-Ratio Reduction Algorithms for OFDM Systems via Constellation Extension Y. J in computational complexity. In [5], a constellation extension technique for PAPR reduction was proposed where in a probabilistic framework [5]-[7]. New de-randomization algorithms are proposed based on a constellation extension

Lu, Wu-Sheng

103

New Peak-to-Average Power-Ratio Reduction Algorithms for OFDM Systems Using Constellation Extension  

E-print Network

New Peak-to-Average Power-Ratio Reduction Algorithms for OFDM Systems Using Constellation Extension is investigated in a probabilistic framework [5]-[7]. A new constellation extension technique for PAPR reduction constellation or by an extended point. In order to find the optimal representation of the OFDM signal, two de

Lu, Wu-Sheng

104

Carbon\\/nitrogen ratio as a control element in aquaculture systems  

Microsoft Academic Search

Controlling the inorganic nitrogen by manipulating the carbon\\/nitrogen ratios is a potential control method for aquaculture systems. This approach seems to be a practical and inexpensive means of reducing the accumulation of inorganic nitrogen in the pond. Nitrogen control is induced by feeding bacteria with carbohydrates, and through the subsequent uptake of nitrogen from the water, by the synthesis of

Yoram Avnimelech

1999-01-01

105

Optimization of Gear Ratio in the Tidal Current Generation System based on Generated Energy  

NASA Astrophysics Data System (ADS)

It is possible to predict generating power of the tidal current generation, because of the tidal current's periodicity. Tidal current generation is more advantageous than other renewable energy sources, when the tidal current generation system is connected to the power system and operated. In this paper, we propose a method used to optimize the gear ratio and generator capacity, that is fundamental design items in the tidal current generation system which is composed of Darrieus type water turbine and squirrel-cage induction generator coupled with gear. The proposed method is applied to the tidal current generation system including the most large-sized turbine that we have developed and studied. This paper shows optimum gear ratio and generator capacity that make generated energy maximum, and verify effectiveness of the proposed method. The paper also proposes a method of selecting maximum generating current velocity in order to reduce the generator capacity, from the viewpoint of economics.

Naoi, Kazuhisa; Shiono, Mitsuhiro; Suzuki, Katsuyuki

106

Universal upper bound on the entropy-to-energy ratio for bounded systems  

Microsoft Academic Search

We present evidence for the existence of a universal upper bound of magnitude 2..pi..R\\/hc to the entropy-to-energy ratio S\\/E of an arbitrary system of effective radius R. For systems with negligible self-gravity, the bound follows from application of the second law of thermodynamics to a gedanken experiment involving a black hole. Direct statistical arguments are also discussed. A microcanonical approach

Jacob Bekenstein

1981-01-01

107

Improving the Accuracy of a Score Fusion Approach Based on Likelihood Ratio in Multimodal Biometric Systems  

Microsoft Academic Search

Multimodal biometric systems integrate information from multiple sources to improve the performance of a typical unimodal\\u000a biometric system. Among the possible information fusion approaches, those based on fusion of match scores are the most commonly\\u000a used. Recently, a framework for the optimal combination of match scores that is based on the likelihood ratio (LR) test has\\u000a been presented. It is

Emanuela Marasco; Carlo Sansone

2009-01-01

108

Reduction of peak-to-average power ratio in transform domain communication systems  

Microsoft Academic Search

Transform Domain Communication Systems (TDCS) are spectrum-scavenging systems which modulate data by a waveform whose magnitude is non-zero only in unused frequency bins, and whose phase is pseudo-random. This creates a noise-like waveform suitable for secure, low probability of intercept (LPI) communications, as well as spectrum-sharing applications. However, it also creates a high peak-to-average power ratio (PAPR). We investigate PAPR

Richard K. Martin; Marshall E. Haker

2009-01-01

109

A bioeconomic model of a ratio-dependent predator-prey system and optimal harvesting  

Microsoft Academic Search

This paper deals with the problem of a ratio-dependent prey-predator model with combined harvesting. The existence of steady\\u000a states and their stability are studied using eigenvalue analysis. Boundedness of the exploited system is examined. We derive\\u000a conditions for persistence and global stability of the system. The possibility of existence of bionomic equilibria has been\\u000a considered. The problem of optimal harvest

T. K. Kar; Swarnakamal Misra; B. Mukhopadhyay

2006-01-01

110

Evaluation of denitrification-nitrification biofilter systems in treating wastewater with low carbon: nitrogen ratios.  

PubMed

A two-stage biological aerated/anoxic filter (BAF) system for denitrification-nitrification was developed to increase nitrogen removal in the treatment of municipal wastewater with low carbon:nitrogen (C/N) ratio [Formula: see text]. This system exhibited a high denitrification efficiency (67%), despite the low C/N ratio, and the ratio of reduced nitrate to consumed organic compounds was greater than the theoretical value due to the minimization of the conversion of organic carbon to biomass growth, the maintenance of low levels of dissolved oxygen in recycled water, and the maximization of use of organic carbon biosorbed inside biomass in the denitrification BAF. The maximum rate of nitrogen removal was achieved at a recycle ratio of 170%, and the headloss in two BAFs was maintained after a 24-h backwash. Biological nitrogen removal in a two-stage BAF system was possible in a short hydraulic retention time (1.2?h) because the maximum reaction rates of nitrifiers and denitrifiers in each column were achieved. PMID:25287910

Kim, Seungjin; Bae, Wookeun; Kim, Moonil; Kim, Jong-Oh; Chung, Jinwook

2015-04-01

111

Influence of tire dynamics on slip ratio estimation of independent driving wheel system  

NASA Astrophysics Data System (ADS)

The independent driving wheel system, which is composed of in-wheel permanent magnet synchronous motor(I-PMSM) and tire, is more convenient to estimate the slip ratio because the rotary speed of the rotor can be accurately measured. However, the ring speed of the tire ring doesn't equal to the rotor speed considering the tire deformation. For this reason, a deformable tire and a detailed I-PMSM are modeled by using Matlab/Simulink. Moreover, the tire/road contact interface(a slippery road) is accurately described by the non-linear relaxation length-based model and the Magic Formula pragmatic model. Based on the relatively accurate model, the error of slip ratio estimated by the rotor rotary speed is analyzed in both time and frequency domains when a quarter car is started by the I-PMSM with a definite target torque input curve. In addition, the natural frequencies(NFs) of the driving wheel system with variable parameters are illustrated to present the relationship between the slip ratio estimation error and the NF. According to this relationship, a low-pass filter, whose cut-off frequency corresponds to the NF, is proposed to eliminate the error in the estimated slip ratio. The analysis, concerning the effect of the driving wheel parameters and road conditions on slip ratio estimation, shows that the peak estimation error can be reduced up to 75% when the LPF is adopted. The robustness and effectiveness of the LPF are therefore validated. This paper builds up the deformable tire model and the detailed I-PMSM models, and analyzes the effect of the driving wheel parameters and road conditions on slip ratio estimation.

Li, Jianqiu; Song, Ziyou; Wei, Yintao; Ouyang, Minggao

2014-11-01

112

Control valve system for a four speed ratio automatic transmission including a dual range regulator valve for controlling independently two upshift ratio changes  

Microsoft Academic Search

This patent describes a control system for a four speed automatic transmission for use in a vehicle driveline to deliver torque from an engine to vehicle traction wheels. The transmission has a driving shaft powered by the engine, a driven shaft, multiple ratio gearing establishing multiple torque delivery paths between the driving and driven shafts and fluid pressure operated clutches

Timte

1987-01-01

113

Signal-to-noise Ratio of Heterodyne Lidar Systems in the Presence of Atmospheric Turbulence  

Microsoft Academic Search

A general expression for the signal-to-noise ratio of a heterodyne lidar system in the presence of atmospheric turbulence is derived which is valid in both the near and far fields of the laser and remote scattering source. We consider the situation where a laser transmitter directs an optical beam at some remote scattering region of interest. The back-scattered light is

H. T. Yura

1979-01-01

114

Signal-to-noise ratio of heterodyne lidar systems in the presence of atmospheric turbulence  

Microsoft Academic Search

A general expression for the signal-to-noise ratio of a heterodyne lidar system in the presence of atmospheric turbulence is derived which is valid both in the near- and far-field of the laser and remoted scattering source. The situation where a laser transmitter directs an optical beam at some remote scattering region of interest is considered. The backscattered light is collected

H. T. Yura

1978-01-01

115

Complement block coding scheme for reducing peak-to-average power ratio of OFDM systems  

Microsoft Academic Search

A new scheme termed as Complement Block Coding (CBC) technique is proposed to reduce the Peak-to-Average Power Ratio (PAPR)\\u000a of OFDM signals. Utilizing the complement bits which are added to the original information bits, this method can effectively\\u000a reduce the PAPR of OFDM systems with random frame size N and the coding rate R?(N??)\\/N, where ? is a positive integer

Tao Jiang; Guangxi Zhu

2004-01-01

116

System for detecting the transmission ratio in an infinitely variable transmission  

SciTech Connect

An improved system is described for detecting the transmission ratio in an infinitely variable transmission for transmitting the power of an internal combustion engine. The transmission comprises primary pulley having a hydraulically shiftable disc and a hydraulic cylinder for shifting the disc and a secondary pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc of the secondary pulley. The transmission has a belt engaged with both pulleys, a hydraulic circuit having a pump for supplying oil, a transmission ratio control valve responsive to engine speed for controlling the oil and for shifting the disc of the primary pulley to change the transmission ratio, and a pressure regulator valve having a spool responsive to the transmission ratio for increasing the line pressure of the hydraulic circuit with an increase of the transmission ratio. A spring is held by a retainer for urging the spool in a direction. The improvement described here comprises: a sensor slidably mounted on a guide tube so as to move in parallel with the axial direction of the primary pulley; the sensor having a sensor head engaged with the disc of the primary pulley and an arm engaged with the retainer so as to shift the spool in dependency on the movement of the disc of the primary pulley to control the line pressure; and a lubricating system comprising passages provided in the guide tube and the sensor so as to communicate a part of the hydraulic circuit with an end opening of the passage of the sensor for lubricating contact surfaces of the head of the sensor and the disc of the primary pulley.

Sakai, Y.

1986-10-28

117

Variable FOV optical illumination system with constant aspect ratio for 2-D array lasers diodes  

NASA Astrophysics Data System (ADS)

In this contribution we present a compact system to create an illumination distribution with a constant aspect ratio 3:4 and FOV from 0.4 to 1 degree. Besides, the system must delivery 40 W from 170 individual laser diodes placed in a regular 2-D array distribution of 10 x 20 mm. The main problem that must be solved is the high asymmetry of the individual sources; emission divergence's ratio 3:73 (0.3 vs. 7.4 degree) combined with the flux holes due to the laser's heat drain. In one axis (divergence of 0.3º) the best design strategy approach is a Galileo telescope but in the other axis a collimator configuration is the best solution. To manage both solutions at the same time is the aim of this contribution. Unfortunately for the Galileo strategy, source dimensions are too large so aspheric surfaces are needed, and the collimator configuration requires an EFL that must change from 573 to 1432 mm. The presented solution uses a set of three fixed anamorphic lenses, two of them pure cylinders, combined with a wheel of anamorphic lenses that have the function to change the FOV of the system. The most important contribution of the design is to obtain a constant final ratio 3:4 from an initial ratio of 3:73 with no losses of energy. The proposed solution produces an illumination pattern with peaks and valleys lower than 40%. This pattern distribution might be unacceptable for a standard illumination solution. However, the actual FOV is used to illuminate far away targets thus air turbulence is enough to homogenize the distribution on the target.

Arasa, J.; de la Fuente, M. C.; Ibañez, C.

2008-09-01

118

Combinatorial screening of photoelectrocatalytic system with high signal/noise ratio.  

PubMed

Solar energy is the most abundant nature resource and plays important roles in the sustainable developments of energy and environment. Scanning photoelectrochemical microscopy provides a high-throughput screening method by introducing the combinatorial technique to prepare the substrate with photoelectrochemical catalyst array. However, the signal/noise (S/N) ratio suffers from the background current of indium-tin oxide or fluorine-doped tin oxide itself, including a transient charge-discharge current of electric double layer and a steady-state photocatalytic current. Here we adopt a facile microfabrication method to isolate the substrate area other than the catalyst array from not only the electrolyte solution but also the light illumination. Consequently, the imaging quality has been promoted dramatically due to suppressed background current. This method provides a high S/N ratio screening method, which will be valuable for the high-throughput optimization of the photoelectrocatalytic system. PMID:25417799

Yuan, Ding; Xiao, Lina; Jia, Jingchun; Zhang, Jie; Han, Lianhuan; Li, Pei; Mao, Bing-Wei; Zhan, Dongping

2014-12-16

119

Estimation of Theaflavins (TF) and Thearubigins (TR) Ratio in Black Tea Liquor Using Electronic Vision System  

NASA Astrophysics Data System (ADS)

Quality of black tea is generally assessed using organoleptic tests by professional tea tasters. They determine the quality of black tea based on its appearance (in dry condition and during liquor formation), aroma and taste. Variation in the above parameters is actually contributed by a number of chemical compounds like, Theaflavins (TF), Thearubigins (TR), Caffeine, Linalool, Geraniol etc. Among the above, TF and TR are the most important chemical compounds, which actually contribute to the formation of taste, colour and brightness in tea liquor. Estimation of TF and TR in black tea is generally done using a spectrophotometer instrument. But, the analysis technique undergoes a rigorous and time consuming effort for sample preparation; also the operation of costly spectrophotometer requires expert manpower. To overcome above problems an Electronic Vision System based on digital image processing technique has been developed. The system is faster, low cost, repeatable and can estimate the amount of TF and TR ratio for black tea liquor with accuracy. The data analysis is done using Principal Component Analysis (PCA), Multiple Linear Regression (MLR) and Multiple Discriminate Analysis (MDA). A correlation has been established between colour of tea liquor images and TF, TR ratio. This paper describes the newly developed E-Vision system, experimental methods, data analysis algorithms and finally, the performance of the E-Vision System as compared to the results of traditional spectrophotometer.

Akuli, Amitava; Pal, Abhra; Ghosh, Arunangshu; Bhattacharyya, Nabarun; Bandhopadhyya, Rajib; Tamuly, Pradip; Gogoi, Nagen

2011-09-01

120

Use of nitrogen stable isotope ratio of periphyton for monitoring nitrogen sources in a river system.  

PubMed

In order to confirm the usefulness of the N stable isotope ratio of periphyton (mainly composed of attached algae) as an indicator for monitoring the N sources in river watersheds, we measured the isotope ratio of periphyton along the Chikuma River. In the river, both the concentrations of dissolved total nitrogen (DTN) and the delta15N values of periphyton increased downstream. Specific nitrogen loading rates (SNLR) calculated from administrative data also showed an increase downstream from 7 to 11 kg N ha(-1) yr(-1), with the increasing contribution by sewage and livestock waste from 6 to 40% to total N loading. There are significant positive relationships between the DTN concentration and the SNLR (r2=0.54, P<0.05), and the delta15N values of periphyton and the SNLR (r2=0.78, P<0.05). The increase in DTN concentration reflected the increase in input of N loading. The increase in delta15N of periphyton might reflect the increase in relative contribution by sewage and livestock waste down the river, especially the increase in sewage. The present study indicates the usefulness of the N stable isotope ratio of periphyton as an indicator for monitoring N sources in a river system. PMID:12523790

Toda, H; Uemura, Y; Okino, T; Kawanishi, T; Kawashima, H

2002-01-01

121

Performance enhancement for long distance BOTDR sensing system based on high extinction ratio probe pulse generator  

NASA Astrophysics Data System (ADS)

The leakage light of an electro-optic modulator (EOM) induced by its finite extinction ratio (ER) may degrade the performance of Brillouin optical time domain reflectometer sensing system, especially for long distance measurement. In this letter, the configuration of a high ER probe pulse generator assisted by synchronous optical switch has been presented. A dual pulses interferometric method was also proposed to determine the dynamic ER value (DER) of the generated probe pulse. Contrast experiments have been performed to verify the effect of the proposed method in a BOTDR system and the results have shown that the performance of a long distance BOTDR sensing system can be improved observably with the proposed high ER probe pulse generator. At the end of a 48.5km sensing fiber, the maximum uncertainty of temperature measurement has been reduced from 5.2° to 0.8° with 25m spatial resolution after we improved the extinction ratio of probe pulse from 35dB to 65dB.

Zhang, Yixin; Xia, Lan; Wu, Xuelin; Zhang, Xuping; Wang, Guanghui

2014-10-01

122

Radiation detection method and system using the sequential probability ratio test  

DOEpatents

A method and system using the Sequential Probability Ratio Test to enhance the detection of an elevated level of radiation, by determining whether a set of observations are consistent with a specified model within a given bounds of statistical significance. In particular, the SPRT is used in the present invention to maximize the range of detection, by providing processing mechanisms for estimating the dynamic background radiation, adjusting the models to reflect the amount of background knowledge at the current point in time, analyzing the current sample using the models to determine statistical significance, and determining when the sample has returned to the expected background conditions.

Nelson, Karl E. (Livermore, CA); Valentine, John D. (Redwood City, CA); Beauchamp, Brock R. (San Ramon, CA)

2007-07-17

123

New Progress on High Fill-Out, Extreme Mass Ratio Overcontact Binary Systems  

NASA Astrophysics Data System (ADS)

High Fill-Out, Extreme Mass Ratio Overcontact Binary (HFEMOB) are a very important source to understand the structure and evolution of the late-type short-period close binary stars, because they are at the late evolutionary stage of these systems. Recently, the detail photometric studies of fifteen such HFEMOBs, including GR Vir, IK Per, FG Hya, TV Mus, CU Tau, V857 Her, GSC619-232, V410 Aur, XY Boo, AH Cnc, QX and, EM Psc, V345 Gem, XY LMi and V1191 Cyg were published. In the present paper, we summarize these results and give some new observations of some HFEMOB candidates.

He, J.; Qian, S.; Soonthornthum, B.

2011-12-01

124

Molecular branching ratio method for intensity calibration of optical systems in the vacuum ultraviolet  

NASA Technical Reports Server (NTRS)

A state-of-the-art review is given of the molecular branching ratio method for intensity calibration in the vacuum ultraviolet. Ways are described for determining both relative and quantitative responses in the wavelength range 1000 A to 3000 A. The molecular band systems which are discussed are the following: H2(B 1 Sigma u +)-(X 1 Sigma g +), H2(C 1 Pi u)-(X 1 Sigma g +), N2(A 1 Pi g)-(X 1 Sigma g +), CO(A 1 Pi)-(X 1 Sigma +), NO(A 2 Sigma +)-(X 2 Pi r), and NO(+) (A 1 Pi)-(X 1 Sigma +).

Mumma, M. J.

1972-01-01

125

The adaptation of Pearce element ratio diagrams to complex high silica systems  

NASA Astrophysics Data System (ADS)

Pearce element ratios (PERs, of Pearce 1968) express geochemical data in a form where variations in absolute compositions of an igneous suite can be evaluated. Generally the denominator value in the ratio is taken as a major element abundance, but it is argued here that Zr provides a more suitable choice. Zr remains incompatible in magmatic systems up to ?68 wt.% SiO2 because zircon fractionation can be suppressed by high melt temperatures and increased volatile contents. The use of Zr thus permits PER modelling to be extended to much higher levels of silica than previously investigated. However, such systems are more complex than those just involving simple basaltic magmas. Besides fractionation, the processes of magma mixing, combined assimilation and fractional crystallization, and the initial degree of partial melting in the mantle source must also be considered. To distinguish and evaluate these processes a set of example suites are investigated from a complex synextensional calc-alkaline province in the western USA. Samples within most individual suites can be modelled by fractionation, however a significant trend orthogonal to the main fractionation vector is also apparent, and open system processes are inferred. Successful modelling is achieved on an inter-suite basis using diagrams with axis functions of ([4(Ca+Na)+0.5(Fe+Mg)]/Zr versus (Si+Al)/Zr). Potential open system evolution paths between mafic end members and crustal contaminants are also displayed and evaluated on these same diagrams. The encouraging results suggest that such PER diagrams may be employed as a versatile tool for investigating the systematics of related igneous suites over a wide area.

Bradshaw, Timothy K.

1992-02-01

126

Copy number ratios determined by two digital polymerase chain reaction systems in genetically modified grains  

NASA Astrophysics Data System (ADS)

Three certified reference materials produced from powdered seeds to measure the copy number ratio sequences of p35S/hmgA in maize containing MON 810 event, p35S/Le1 in soybeans containing GTS 40-3-2 event and DREB1A/acc1 in wheat were produced according to the ISO Guides 34 and 35. In this paper, we report digital polymerase chain reaction (dPCR) protocols, performance parameters and results of copy number ratio content of genetically modified organisms (GMOs) in these materials using two new dPCR systems to detect and quantify molecular deoxyribonucleic acid: the BioMark® (Fluidigm) and the OpenArray® (Life Technologies) systems. These technologies were implemented at the National Institute of Metrology in Mexico (CENAM) and in the Reference Center for GMO Detection from the Ministry of Agriculture (CNRDOGM), respectively. The main advantage of this technique against the more-used quantitative polymerase chain reaction (qPCR) is that it generates an absolute number of target molecules in the sample, without reference to standards or an endogenous control, which is very useful when not much information is available for new developments or there are no standard reference materials in the market as in the wheat case presented, or when it was not possible to test the purity of seeds as in the maize case presented here. Both systems reported enhanced productivity, increased reliability and reduced instrument footprint. In this paper, the performance parameters and uncertainty of measurement obtained with both systems are presented and compared.

Pérez Urquiza, M.; Acatzi Silva, A. I.

2014-02-01

127

Performance and limits of liquid chromatography isotope ratio mass spectrometry system for halogenated compounds  

NASA Astrophysics Data System (ADS)

Compound Specific Isotope Analysis (CSIA) has been an important step for the assessment of the origin and fate of compounds in environmental science.[1] Biologically or pharmaceutically important compounds often are not amenable for gas chromatographic separation because of high polarity and lacking volatility, thermostability. In 2004 liquid chromatography isotope ratio mass spectrometry (LC-IRMS) became commercially available. LC-IRMS system intent a quantitative conversion of analytes separation into CO2 via wet oxidation with sodium persulfate in the presence of phosphoric acid while analytes are still dissolved in the aqueous liquid phase.[2] The aim of this study is to analyze the oxidation capacity of the interface of the LC-IRMS system and determine which parameters could improve oxidation of compounds which are resistant to persulfate oxidation. Oxidation capacity of the liquid chromatography isotope ratio mass spectrometry system was tested with halogenated acetic acid and a set of aromatic compounds with different substitutes. Acetic acid (AA) was taken as a model compound for complete oxidation and compared to the oxidation of other analytes on a molar basis. Correct values were obtained for di- and mono chlorinated and fluorinated and also for tribrominated acetic acid and for all studied aromatic compounds. Incomplete oxidation for trichloroacetic (TCAA) and trifluoroacetic (TFAA) acid was revealed with lower recovery compared to acetic acid and isotope fractionation leading to depleted carbon isotope composition compared to values obtained with an elementary analyzer connected to an isotope mass spectrometer Several optimization steps were tried in order to improve the oxidation of TCAA and TFAA: (i) increasing the concentration of the oxidizing agent, (ii) variation of flow rate of the oxidizing and acid solution, (iii) variation of flow rate of liquid chromatography pump (iv) addition of a catalyzer. These modifications lead to longer reaction time in the coil and increase in the concentration of radical but complete combustion of highly chlorinated or fluorinated compounds was not achieved. Due to these findings the limit for a LC-IRMS system for similar structure compounds can be predicted. 1. Elsner, M., et al., Current challenges in compound-specific stable isotope analysis of environmental organic contaminants. Analytical and Bioanalytical Chemistry, 2012. 403(9): p. 2471-2491. 2. Krummen, M., et al., A new concept for isotope ratio monitoring liquid chromatography/mass spectrometry. Rapid Communications in Mass Spectrometry, 2004. 18(19): p. 2260-2266.

Gilevska, Tetyana; Gehre, Matthias; Richnow, Hans

2014-05-01

128

A gas chromatography/pyrolysis/isotope ratio mass spectrometry system for high-precision dD measurements  

E-print Network

A gas chromatography/pyrolysis/isotope ratio mass spectrometry system for high-precision d we present a highly automated, high-precision online gas chromatography/pyrolysis/isotope ratio monitoring mass spectrometry (GC/P/irmMS) technique for the analysis of dD(CH4). It includes gas extraction

Fischer, Hubertus

129

DEEP, LOW MASS RATIO OVERCONTACT BINARY SYSTEMS. XI. V1191 CYGNI  

SciTech Connect

Complete CCD photometric light curves in BV(RI){sub c} bands obtained on one night in 2009 for the short-period close-binary system V1191 Cygni are presented. A new photometric analysis with the 2003 version of the Wilson-Van Hamme code shows that V1191 Cyg is a W-type overcontact binary system and suggests that it has a high degree of overcontact (f = 68.6%) with very low mass ratio, implying that it is at the late stage of overcontact evolution. The absolute parameters of V1191 Cyg are derived using spectroscopic and photometric solutions. Combining new determined times of light minimum with others published in the literature, the period change of the binary star is investigated. A periodic variation, with a period of 26.7 years and an amplitude of 0.023 days, was discovered to be superimposed on a long-term period increase (dP/dt = +4.5({+-} 0.1) x 10{sup -7} days yr{sup -1}). The cyclic period oscillation may be caused by the magnetic activity cycles of either of the components or the light-time effect due to the presence of a third body with a mass of m{sub 3} = 0.77 M{sub sun} and an orbital radius of a{sub 3} = 7.6 AU, when this body is coplanar to the orbit of the eclipsing pair. The secular orbital period increase can be interpreted as a mass transfer from the less massive component to the more massive one. With the period increases, V1191 Cyg will evolve from its present low mass ratio, high filled overcontact state to a rapidly rotating single star when its orbital angular momentum is less than three times the total spin angular momentum. V1191 Cyg is too blue for its orbital period and it is an unusual W-type overcontact system with such a low mass ratio and high fill-out overcontact configuration, which is worth monitoring continuously in the future.

Zhu, L. Y.; Qian, S. B.; He, J. J.; Liu, L. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, 650011 Kunming (China); Soonthornthum, B., E-mail: zhuly@ynao.ac.cn [National Astronomical Research Institute of Thailand/Ministry of Science and Technology, Bangkok (Thailand)

2011-10-15

130

A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system.  

PubMed

The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield was significantly higher in the lower hydraulic loading rate. Fish production, plant growth and percentage nutrient removal were highest at hydraulic loading rate of 1.28 m/day. The ratio of fish to plant production has been calculated to balance nutrient generation from fish with nutrient removal by plants and the optimum ratio was 15-42 gram of fish feed/m(2) of plant growing area. Each unit in RAS was evaluated in terms of oxygen demand. Using specified feeding regime, mass balance equations were applied to quantify the waste discharges from rearing tanks and treatment units. The waste discharged was found to be strongly dependent on hydraulic loading rate. PMID:19819130

Endut, Azizah; Jusoh, A; Ali, N; Wan Nik, W B; Hassan, A

2010-03-01

131

Geodesic deviations: modeling extreme mass-ratio systems and their gravitational waves  

NASA Astrophysics Data System (ADS)

The method of geodesic deviations has been applied to derive accurate analytic approximations to geodesics in Schwarzschild spacetime. The results are used to construct analytic expressions for the source terms in the Regge-Wheeler and Zerilli-Moncrief equations, which describe the propagation of gravitational waves emitted by a compact massive object moving in the Schwarzschild background spacetime. The wave equations are solved numerically to provide the asymptotic form of the wave at large distances for a series of non-circular bound orbits with periastron distances up to the ISCO radius, and the power emitted in gravitational waves by the extreme mass-ratio binary system is computed. The results compare well with those of purely numerical approaches.

Koekoek, G.; van Holten, J. W.

2011-11-01

132

On ionisation effects and abundance ratios in damped Lyman-alpha systems  

E-print Network

The similarity between observed velocity structures of Al III and singly ionised species in damped Lyman-alpha systems (DLAs) suggests the presence of ionised gas in the regions where most metal absorption lines are formed. To explore the possible implications of ionisation effects we construct a simplified two-region model for DLAs consisting of an ionisation bounded region with an internal radiation field and a neutral region with a lower metal content. Within this framework we find that ionisation effects are important. If taken into account, the element abundance ratios in DLAs are quite consistent with those observed in Milky Way stars and in metal-poor H II regions in blue compact dwarf galaxies. In particular we cannot exclude the same primary N origin in both DLAs and metal-poor galaxies. From our models no dust depletion of heavy elements needs to be invoked; little depletion is however not excluded.

Daniel Schaerer; Yuri Izotov; Corinne Charbonnel

2000-09-07

133

Spatiotemporal complexity of a ratio-dependent predator-prey system  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the emergence of a ratio-dependent predator-prey system with Michaelis-Menten-type functional response and reaction diffusion. We obtain the conditions of Hopf, Turing, and wave bifurcation in a spatial domain. Furthermore, we present a theoretical analysis of evolutionary processes that involves organisms distribution and their interaction of spatially distributed population with local diffusion. The results of numerical simulations reveal that the typical dynamics of population density variation is the formation of isolated groups, i.e., stripelike or spotted or coexistence of both. Our study shows that the spatially extended model has not only more complex dynamic patterns in the space, but also chaos and spiral waves. It may help us better understand the dynamics of an aquatic community in a real marine environment.

Wang, Weiming; Liu, Quan-Xing; Jin, Zhen

2007-05-01

134

Distribution function for the system of galaxies for any ratio of gravitational potential to kinetic energies  

NASA Astrophysics Data System (ADS)

We evaluate a distribution function for the system of galaxies clustering gravitationally in an expanding universe on the basis of statistical mechanics. We extend our previous work to incorporate the effect of any ratio of gravitational potential to kinetic energies. We determine the cosmological many-body partition function inclusive of higher order terms and calculate all thermodynamic quantities and the distribution function from it. We find that our new results are consistent with the previous ones, particularly in the large bar{N} (average number of galaxies) limit. We also investigate the effect on clustering parameter b and find our new results in very good agreement with the previous ones in the small b limit. We find that for large b, the departure from the original distribution function is greater. We also observe that the effect of softening on the distribution function is consistent with our previous work.

Ahmad, Farooq; Malik, Manzoor A.; Mir, Hameeda

2014-02-01

135

Monte Carlo simulation of two-dimensional hard body systems with extreme values of the Poisson's ratio  

NASA Astrophysics Data System (ADS)

Monte Carlo computer simulations with variable shape of the periodic box were performed for a few two-dimensional, hard-body models showing elastically isotropic solid phases. Two examples of homo-molecular (i.e. consisting of identical molecules) systems of anisotropic molecules are discussed which form unusual solid phases, showing negative Poisson's ratio and know as auxetic ones, at densities and pressures higher than the elastically isotropic solid phases. Sharp extremes of the Poisson's ratio were observed for both systems at freezing of the orientational degrees of freedom of the molecules: a minimum was observed for the system for which the auxetic phase with frozen rotation is isotropic and a maximum was found for the other system. This indicates that isotropic auxetic phases can have auxetic precursors with much more negative Poisson's ratios than those characterizing the auxetic phases themselves. An example of a hetero-molecular (i.e. mixture consisting of different molecules), elastically isotropic system is also discussed - the polydisperse hard disc system. The simulations revealed a maximum of the Poisson's ratio in the close packing limit at any nonzero polydispersity. Although no manifestation of any auxetic behaviour has been found in this system, the obtained results indicate other unusual effect - a jump (discontinuity) of the Poisson's ratio at close packing when the polydispersity tends to zero. The results obtained in this work demonstrate that the Poisson's ratio can play the role of a sensitive indicator of (at least) some structural changes in solids.

Tretiakov, K. V.; Wojciechowski, K. W.

2005-03-01

136

Nitrogen Isotope Ratios of Juvenile Winter Flounder as an Indicator of Anthropogenic Nitrogen Inputs to Estuarine Systems  

EPA Science Inventory

Nitrogen isotope ratios (?15N) were measured in muscle tissue of juvenile winter flounder, Pseudopleuronectes americanus, collected from several estuarine systems (lagoons, river, bay) along the coast of Rhode Island, USA over a three-year period. Significant differences i...

137

Reliability analysis of a passive cooling system using a response surface with an application to the Flexible Conversion Ratio Reactor  

E-print Network

A comprehensive risk-informed methodology for passive safety system design and performance assessment is presented and demonstrated on the Flexible Conversion Ratio Reactor (FCRR). First, the methodology provides a framework ...

Fong, Christopher J. (Christopher Joseph)

2008-01-01

138

A study of signal to noise ratio, lane counting, and position accuracy using the Omega navigation system  

E-print Network

A forty-hour flight program was completed to study signal to noise ratio, lane counting and position accuracy using a low cost Omega navigation system in a general aviation aircraft. Specific test objectives were developed ...

Francisco, Glen Leif

1976-01-01

139

Thermodynamic Modeling and Analysis of the Ratio of Heat to Power Based on a Conceptual CHP System  

E-print Network

The CHP system not only produces electrical energy, but also produces thermal energy. An extensive analysis of the CHP market reveals that one of the most important engineering characteristics is flexibility. A variable heat-to-power ratio has...

Liu, Z.; Li, X.; Liu, Z.

2006-01-01

140

Signal to noise ratio of energy selective x-ray photon counting systems with pileup  

PubMed Central

Purpose: To derive fundamental limits on the effect of pulse pileup and quantum noise in photon counting detectors on the signal to noise ratio (SNR) and noise variance of energy selective x-ray imaging systems. Methods: An idealized model of the response of counting detectors to pulse pileup is used. The model assumes a nonparalyzable response and delta function pulse shape. The model is used to derive analytical formulas for the noise and energy spectrum of the recorded photons with pulse pileup. These formulas are first verified with a Monte Carlo simulation. They are then used with a method introduced in a previous paper [R. E. Alvarez, “Near optimal energy selective x-ray imaging system performance with simple detectors,” Med. Phys. 37, 822–841 (2010)] to compare the signal to noise ratio with pileup to the ideal SNR with perfect energy resolution. Detectors studied include photon counting detectors with pulse height analysis (PHA), detectors that simultaneously measure the number of photons and the integrated energy (NQ detector), and conventional energy integrating and photon counting detectors. The increase in the A-vector variance with dead time is also computed and compared to the Monte Carlo results. A formula for the covariance of the NQ detector is developed. The validity of the constant covariance approximation to the Cramèr–Rao lower bound (CRLB) for larger counts is tested. Results: The SNR becomes smaller than the conventional energy integrating detector (Q) SNR for 0.52, 0.65, and 0.78 expected number photons per dead time for counting (N), two, and four bin PHA detectors, respectively. The NQ detector SNR is always larger than the N and Q SNR but only marginally so for larger dead times. Its noise variance increases by a factor of approximately 3 and 5 for the A1 and A2 components as the dead time parameter increases from 0 to 0.8 photons per dead time. With four bin PHA data, the increase in variance is approximately 2 and 4 times. The constant covariance approximation to the CRLB is valid for larger counts such as those used in medical imaging. Conclusions: The SNR decreases rapidly as dead time increases. This decrease places stringent limits on allowable dead times with the high count rates required for medical imaging systems. The probability distribution of the idealized data with pileup is shown to be accurately described as a multivariate normal for expected counts greater than those typically utilized in medical imaging systems. The constant covariance approximation to the CRLB is also shown to be valid in this case. A new formula for the covariance of the NQ detector with pileup is derived and validated. PMID:25370642

Alvarez, Robert E.

2014-01-01

141

Control system for a multiple ratio transmission having a lockup clutch torque converter  

SciTech Connect

This patent describes a power transmission mechanism for a driveline for a vehicle powered by an internal combustion engine. The process comprises: a hydrokinetic torque converter having a bladed impeller housing driven by the engine, a bladed turbine in the housing, a bladed stator and a turbine shaft connected to the turbine; multiple ratio gearing having a torque input member and a torque output member with plural torque flow paths defined by gear elements between the input and output members and having clutch and brake servo means for establishing selectively four forward driving speed ratios and a reverse ratio; and the highest speed ratio being an overdrive, the second highest speed ratio being a direct one-to-one speed ratio and the third highest speed ratio being an underdrive.

Van Selous, J.S.

1987-05-19

142

The influence of external source intensity in accelerator/target/blanket system on conversion ratio and fuel cycle  

NASA Astrophysics Data System (ADS)

The analysis of neutron balance relation for a subcritical system with external source shows that a high ratio of neutron utilization (conversion ratio, breeding ratio) much exceeding similar values for nuclear reactors (both thermal or fast spectrum) is reachable in accelerator/target/blanket system with high external neutron source intensity. An accelerator/target/blanket systems with thermal power in blanket about 1850 Mwt and operating during 30 years have been investigated. Continual feed up by plutonium (fissile material) and Tc-99 (transmuted material) was assumed. Accelerator beam intensity differed 6.3 times (16 mA-Case 1, and 100 mA-Case 2). Conversion ratio (CR) was defined as the ratio of Tc-99 nuclei transmuted to the number of Pu nuclei consumed. The results for two cases are as follows: Case 1Case 2CR 0.77 1.66N(LWR) 8.6 19.1Power MWt(el) 512 225 where N(LWR)-number of LWRs(3000 MWt(th)) from which yearly discharge of Tc-99 is transmuted during 30 years. High value of conversion ratio considerably exceeding 1 (CR=1.66) was obtained in the system with high source intensity as compared with low source system (CR=0.77). Net output of electric power of high source intensity system is about twice lower due to consumption of electric power for accelerator feed up. The loss of energy for Tc-99 transmutation is estimated as 40 Mev(el)/nuclei. Yet high conversion ratio (or breeding ratio) achievable in electronuclear installations with high intensity of external source can effectively be used to close fuel cycle (including incineration of wastes) or to develop growing nuclear power production system.

Kochurov, Boris P.

1995-09-01

143

The differential Howland current source with high signal to noise ratio for bioimpedance measurement system  

SciTech Connect

The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 M?, and below 1 MHz the output impedance can arrive to 200 K?. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

Liu, Jinzhen; Li, Gang; Lin, Ling, E-mail: linling@tju.edu.cn [State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People's Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin (China); Qiao, Xiaoyan [College of Physics and Electronic Engineering, Shanxi University, Shanxi (China); Wang, Mengjun [School of Information Engineering, Hebei University of Technology, Tianjin (China); Zhang, Weibo [Institute of Acupuncture and Moxibustion China Academy of Chinese Medical Sciences, Beijing (China)

2014-05-15

144

Signal-to-noise ratio performance for detection systems of quantum dot multiplexed optical encoding  

NASA Astrophysics Data System (ADS)

The wavelength and intensity of the spectral emission of a group of quantum dots can be altered by varying the size of the quantum dots (wavelength) and the number of the quantum dots (intensity). In this way, information and be encoded into the spectral characteristics of the group of quantum dots emission. This approach has been proposed for the application of tagging thousands of biomolecules as well as replacing barcodes as a means to identify objects. The potential in this system rests in the ability to achieve a high information density. In this paper we model and measure the noise in the readout system that will contribute to the decrease of the information density. We also propose an alternate optical detector as a possibly simpler and cheaper design. Our results demonstrate that the signal-to-noise ratio for both the CCD and photodiode detectors has a linear relationship with time. To achieve comparable SNR, approximately 30dB, in both detectors we note that the CCD-based spectrometer requires integration times on the order of hundreds of milliseconds while the photodiode only requires tens of microseconds.

Goss, K. C.; Potter, M. E.; Messier, G. G.

2010-06-01

145

A Toy Model for Testing Finite Element Methods to Simulate Extreme-Mass-Ratio Binary Systems  

E-print Network

Extreme mass ratio binary systems, binaries involving stellar mass objects orbiting massive black holes, are considered to be a primary source of gravitational radiation to be detected by the space-based interferometer LISA. The numerical modelling of these binary systems is extremely challenging because the scales involved expand over several orders of magnitude. One needs to handle large wavelength scales comparable to the size of the massive black hole and, at the same time, to resolve the scales in the vicinity of the small companion where radiation reaction effects play a crucial role. Adaptive finite element methods, in which quantitative control of errors is achieved automatically by finite element mesh adaptivity based on posteriori error estimation, are a natural choice that has great potential for achieving the high level of adaptivity required in these simulations. To demonstrate this, we present the results of simulations of a toy model, consisting of a point-like source orbiting a black hole under the action of a scalar gravitational field.

Carlos F. Sopuerta; Pengtao Sun; Pablo Laguna; Jinchao Xu

2006-01-19

146

Enhancing Multiple-Transiting Planet System Validation with Transit Duration Ratios  

NASA Astrophysics Data System (ADS)

The recent discoveries of three planets transiting Kepler-9 (Holman et al. 2010; Torres et al. 2011), six densely packed planets transiting Kepler-11 (Lissauer et al. 2011), and a total of 170 stars with multiple transiting planet candidates (Borucki et al. 2011; Steffen et al. 2010) bode well for the future of multiple-transiting planet systems (MTPSs). For many faint (Kp>14) Kepler targets, traditional confirmation by radial velocities is not practical. Fortunately, detailed light curve analysis can eliminate the vast majority of false-positive scenarios and statistically validate such systems (Torres et al. 2011; Fressin et al. 2011). We explore the utility of the ratio of the observed transit durations in MTPSs for validating candidate MTPSs. After normalizing by a function of orbital periods, we obtain a parameter with a distribution centered on unity for multiple planets around the same star, but markedly different for certain blend scenarios. Using the Kepler Input Catalog and galactic stellar population models, we investigate these distributions through Monte Carlo simulations of four scenarios: 1) one star with two planets, 2) one star with one planet blended with an eclipsing binary, 3) two eclipsing binaries, and 4) two stars each with one planet. We discuss the utility of this statistics for in planet validation and estimating the false alarm probabilities for candidate systems identified by Kepler. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA, Science Mission Directorate. R.C.M. is supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-0802270.

Morehead, Robert C.; Ford, E. B.; Prša, A.; Ragozzine, D.

2011-09-01

147

Ratiometric dosing of anticancer drug combinations: controlling drug ratios after systemic administration regulates therapeutic activity in tumor-bearing mice.  

PubMed

Anticancer drug combinations can act synergistically or antagonistically against tumor cells in vitro depending on the ratios of the individual agents comprising the combination. The importance of drug ratios in vivo, however, has heretofore not been investigated, and combination chemotherapy treatment regimens continue to be developed based on the maximum tolerated dose of the individual agents. We systematically examined three different drug combinations representing a range of anticancer drug classes with distinct molecular mechanisms (irinotecan/floxuridine, cytarabine/daunorubicin, and cisplatin/daunorubicin) for drug ratio-dependent synergy. In each case, synergistic interactions were observed in vitro at certain drug/drug molar ratio ranges (1:1, 5:1, and 10:1, respectively), whereas other ratios were additive or antagonistic. We were able to maintain fixed drug ratios in plasma of mice for 24 hours after i.v. injection for all three combinations by controlling and overcoming the inherent dissimilar pharmacokinetics of individual drugs through encapsulation in liposomal carrier systems. The liposomes not only maintained drug ratios in the plasma after injection, but also delivered the formulated drug ratio directly to tumor tissue. In vivo maintenance of drug ratios shown to be synergistic in vitro provided increased efficacy in preclinical tumor models, whereas attenuated antitumor activity was observed when antagonistic drug ratios were maintained. Fixing synergistic drug ratios in pharmaceutical carriers provides an avenue by which anticancer drug combinations can be optimized prospectively for maximum therapeutic activity during preclinical development and differs from current practice in which dosing regimens are developed empirically in late-stage clinical trials based on tolerability. PMID:16891472

Mayer, Lawrence D; Harasym, Troy O; Tardi, Paul G; Harasym, Natashia L; Shew, Clifford R; Johnstone, Sharon A; Ramsay, Euan C; Bally, Marcel B; Janoff, Andrew S

2006-07-01

148

Carrier-to-noise ratio for an equal-gain coherent laser radar receiver array system: theory and experiment  

Microsoft Academic Search

In this paper, a theoretical comparison is made of the mean carrier-to-noise ratio (CNR) for a coherent (heterodyne detection) equal gain (EG) optical array receiver system with that predicted by a conventional single-aperture monolithic coherent detector system. Our analysis shows that the mean CNR for an EG array receiver system improves significantly over that of a single aperture system. Experimental

Larry C. Andrews; Deborah E. Kelly; Richard L. Phillips; James E. Harvey; Jing Xu; Chie L. Gagge; Ali Notash; Giovanni Luvera; R. Glenn Sellar

1998-01-01

149

Mobile lidar system for measurement of water vapor mixing ratio and ozone number density  

NASA Technical Reports Server (NTRS)

The Water Vapor Lidar was modified and extended to make differential absorption measurements of ozone. Water vapor measurements make use of a weak molecular scattering process known as Raman scattering. It is characterized by a shift in wavelength of the scattered beam of light relative to the incident one. Some of the energy of the incident photon is converted to vibrational or rotational energy within the molecule leaving the scattered photon shifted to a slightly longer wavelength. When performing water vapor measurements, profiles are acquired of water vapor mixing ratio from near the ground to beyond 7 km every 2 minutes. By forming a color composite image of the individual profiles, the spatial and temporal evolution of water vapor is visible with vertical resolution of 75 to 150m and temporal resolution of 2 minutes. The ozone lidar is intended for use as a cross calibration facility for other stationary ozone lidar systems. The ozone measurement employs the technique known as differential absorption. The backscattered laser radiation from two different wavelengths is measured. Successful measurements of 308 nm returns were made from 80 km with an averaging period of 6 hours. Using these data and a standard atmosphere density curve, an ozone number density profile was made which agrees very well with the standard ozone curve between 20 and 40 km.

Whiteman, D.

1988-01-01

150

A synthetic sex ratio distortion system for the control of the human malaria mosquito  

PubMed Central

It has been theorized that inducing extreme reproductive sex ratios could be a method to suppress or eliminate pest populations. Limited knowledge about the genetic makeup and mode of action of naturally occurring sex distorters and the prevalence of co-evolving suppressors has hampered their use for control. Here we generate a synthetic sex distortion system by exploiting the specificity of the homing endonuclease I-PpoI, which is able to selectively cleave ribosomal gene sequences of the malaria vector Anopheles gambiae that are located exclusively on the mosquito’s X chromosome. We combine structure-based protein engineering and molecular genetics to restrict the activity of the potentially toxic endonuclease to spermatogenesis. Shredding of the paternal X chromosome prevents it from being transmitted to the next generation, resulting in fully fertile mosquito strains that produce >95% male offspring. We demonstrate that distorter male mosquitoes can efficiently suppress caged wild-type mosquito populations, providing the foundation for a new class of genetic vector control strategies. PMID:24915045

Galizi, Roberto; Doyle, Lindsey A.; Menichelli, Miriam; Bernardini, Federica; Deredec, Anne; Burt, Austin; Stoddard, Barry L.; Windbichler, Nikolai; Crisanti, Andrea

2014-01-01

151

A synthetic sex ratio distortion system for the control of the human malaria mosquito.  

PubMed

It has been theorized that inducing extreme reproductive sex ratios could be a method to suppress or eliminate pest populations. Limited knowledge about the genetic makeup and mode of action of naturally occurring sex distorters and the prevalence of co-evolving suppressors has hampered their use for control. Here we generate a synthetic sex distortion system by exploiting the specificity of the homing endonuclease I-PpoI, which is able to selectively cleave ribosomal gene sequences of the malaria vector Anopheles gambiae that are located exclusively on the mosquito's X chromosome. We combine structure-based protein engineering and molecular genetics to restrict the activity of the potentially toxic endonuclease to spermatogenesis. Shredding of the paternal X chromosome prevents it from being transmitted to the next generation, resulting in fully fertile mosquito strains that produce >95% male offspring. We demonstrate that distorter male mosquitoes can efficiently suppress caged wild-type mosquito populations, providing the foundation for a new class of genetic vector control strategies. PMID:24915045

Galizi, Roberto; Doyle, Lindsey A; Menichelli, Miriam; Bernardini, Federica; Deredec, Anne; Burt, Austin; Stoddard, Barry L; Windbichler, Nikolai; Crisanti, Andrea

2014-01-01

152

Improving Compression Ratio, Area Overhead, and Test Application Time for System-on-a-Chip Test Data Compression\\/Decompression  

Microsoft Academic Search

This paper proposes a new test data compression\\/decompression method for systems-on-a-chip. Themethod is based on analyzing the factors that influencetest parameters: compression ratio, area overhead and testapplication time. To improve compression ratio, the newmethod is based on a Variable-length Input Huffman Coding(VIHC), which fully exploits the type and length of the patterns,as well as a novel mapping and reordering algorithmproposed

Paul Theo Gonciari; Bashir M. Al-Hashimi; Nicola Nicolici

2002-01-01

153

Effects of Different Eddy Covariance Correction Schemes on Energy Balance Closure and Comparisons with the Modified Bowen Ratio System  

Technology Transfer Automated Retrieval System (TEKTRAN)

Eddy covariance (EC) and modified Bowen ratio (MBR) systems typically yield subtly different estimates of H, LE, and Fc. Our study analyzed the discrepancies between EC and MBR systems by first considering the role of the data processing algorithm used to estimate fluxes using EC and later examinin...

154

Computer experiments on periodic systems identification using rotor blade transient flapping-torsion responses at high advance ratio  

NASA Technical Reports Server (NTRS)

Systems identification methods have recently been applied to rotorcraft to estimate stability derivatives from transient flight control response data. While these applications assumed a linear constant coefficient representation of the rotorcraft, the computer experiments described in this paper used transient responses in flap-bending and torsion of a rotor blade at high advance ratio which is a rapidly time varying periodic system.

Hohenemser, K. H.; Prelewicz, D. A.

1974-01-01

155

Systemic acid load from the diet affects maximal exercise respiratory exchange ratio  

PubMed Central

Background A maximal exercise respiratory exchange ratio (RERmax) ?1.10 is commonly used as a criterion to determine if a “true” maximal oxygen uptake (VO2max) has been attained during maximal-effort exercise testing. Because RERmax is heavily influenced by CO2 production from acid buffering during maximal exercise, we postulated that dietary acid load, which affects acid-base regulation, might contribute to variability in RERmax. Purpose To determine if a habitual dietary intake that promotes systemic alkalinity results in higher RERmax during VO2max testing. Methods Sedentary men and women (47-63y, n=57) with no evidence of cardiovascular disease underwent maximal graded treadmill exercise tests. VO2max and RERmax were measured with indirect calorimetry. Habitual diet was assessed for its long-term effect on systemic acid-base status by performing nutrient analysis of food diaries and using this information to calculate the potential renal acid load (PRAL). Participants were grouped into tertiles based on PRAL. Results The lowest PRAL tertile (alkaline PRAL) had higher RERmax values (1.21±0.01, p?0.05) than the middle tertile (1.17±0.01) and highest PRAL tertile (1.15±0.01). There were no significant differences (all p?0.30) among PRAL tertiles for RER at submaximal exercise intensities of 70%, 80%, or 90% VO2max. After controlling for age, sex, VO2max, and maximal heart rate (HRmax), regression analysis demonstrated that 19% of the variability in RERmax was attributed to PRAL (r=?0.43, p=0.001). Unexpectedly, HRmax was lower (p?0.05) in the low PRAL tertile (164±3 beats/min) versus the highest PRAL tertile (173±3 beats/min). Conclusion These results suggest that individuals on a diet that promotes systemic alkalinity may more easily achieve the RERmax criterion of ?1.10 which might lead to false-positive conclusions about achieving maximal effort and VO2max during graded exercise testing. PMID:21912302

Niekamp, Katherine; Zavorsky, Gerald S.; Fontana, Luigi; McDaniel, Jennifer L; Villareal, Dennis T; Weiss, Edward P

2013-01-01

156

Design of passive decay heat removal system for the lead cooled flexible conversion ratio fast reactor  

E-print Network

The lead-cooled flexible conversion ratio fast reactor shows many benefits over other fast-reactor designs; however, the higher power rating and denser primary coolant present difficulties for the design of a passive decay ...

Whitman, Joshua (Joshua J.)

2007-01-01

157

Chondrites - Initial strontium-87/strontium-86 ratios and the early history of the solar system.  

NASA Technical Reports Server (NTRS)

A sodium-poor, calcium-rich inclusion in the carbonaceous chondrite Allende had a Sr-87/Sr-86 ratio at the time of its formation of 0.69880, as low a value as that found in any other meteorite. The higher Sr-87/Sr-86 ratios found in ordinary chondrites indicate that their formation or isotopic equilibration occurred tens of millions of years later.

Wetherill, G. W.; Mark, R.; Lee-Hu, C.

1973-01-01

158

Implications for the False-positive Rate in Kepler Planet Systems from Transit Duration Ratios  

NASA Astrophysics Data System (ADS)

Confirming transiting exoplanet candidates through traditional follow-up methods is challenging, especially for faint host stars. Most of Kepler's validated planets relied on statistical methods to separate true planets from false-positives. Multiple transiting planet systems (MTPS) have been previously shown to have low false-positive rates and over 851 planets in MTPSs have been statistically validated so far (Lissauer et al. 2014; Rowe et al. 2014). We show that the period-normalized transit duration ratio (?) offers additional information that can be used to establish the planetary nature of these systems. We briefly discuss the observed distribution of ? for the Q1-Q16 Kepler Candidate Search. We also utilize ? to develop a Bayesian statistical framework combined with Monte Carlo methods to determine which pairs of planet candidates in a MTPS are consistent with the planet hypothesis for a sample of 676 MTPSs that include both candidate and confirmed planets. This analysis proves to be efficient and advantageous in that it only requires catalog-level bulk candidate properties and galactic population modeling to compute the probabilities of a myriad of stellar blend scenarios, without needing additional observational follow-up. Our results agree with the previous results of a low false-positive rate in the Kepler MTPSs. Out of our sample of 1,358 pairs of candidates, we find that about 100 pairs have a probability greater than 0.99 of being a MTPS associated with the target star, over 800 pairs have a probability greater than 0.99 of being a MTPS associated with the target star or another star blended in the photometric aperture. Further more, we find that well over a 1,000 pairs have a probability greater than 0.99 to be planetary in nature, either orbiting the same star or separately orbiting two different stars in the aperture. This implies, independently of any other estimates, that most of the MTPSs detected by Kepler are very likely to be planetary in nature, but that a substantial fraction could be orbiting stars other than the putative target star, and therefore may be subject to significant error in the inferred planet parameters resulting from unknown or mismeasured stellar host attributes.

Morehead, Robert C.; Ford, Eric B.

2015-01-01

159

Influence of COD/sulfate ratios on the integrated reactor system for simultaneous removal of carbon, sulfur and nitrogen.  

PubMed

An integrated reactor system was developed for the simultaneous removal of carbon, sulfur and nitrogen from sulfate-laden wastewater and for elemental sulfur (S(0)) reclamation. The system mainly consisted of an expanded granular sludge bed (EGSB) for sulfate reduction and organic carbon removal (SR-CR), an EGSB for denitrifying sulfide removal (DSR), a biological aerated filter for nitrification and a sedimentation tank for sulfur reclamation. This work investigated the influence of chemical oxygen demand (COD)/sulfate ratios on the performance of the system. Influent sulfate and ammonium were fixed to the level of 600 mg SO4(2-) L(-1) and 120 mg NH4(+) L(-1), respectively. Lactate was introduced to generate COD/SO4(2-) = 0.5:1, 1:1, 1.5:1, 2:1, 3:1, 3.5:1 and 4:1. The experimental results indicated that sulfate could be efficiently reduced in the SR-CR unit when the COD/SO4(2-) ratio was between 1:1 and 3:1, and sulfate reduction was inhibited by the growth of methanogenic bacteria when the COD/SO4(2-) ratio was between 3.5:1 and 4:1. Meanwhile, the Org-C/S(2-)/NO3(-) ratios affected the S(0) reclamation efficiency in the DSR unit. When the influent COD/SO4(2-) ratio was between 1:1 and 3:1, appropriate Org-C/S(2-)/NO3(-) ratios could be achieved to obtain a maximum S(0) recovery in the DSR unit. For the microbial community of the SR-CR unit at different COD/SO4(2-) ratios, 16S rRNA gene-based high throughput Illumina MiSeq sequencing was used to analyze the diversity and potential function of the dominant species. PMID:25768217

Yuan, Ye; Chen, Chuan; Zhao, Youkang; Wang, Aijie; Sun, Dezhi; Huang, Cong; Liang, Bin; Tan, Wenbo; Xu, Xijun; Zhou, Xu; Lee, Duu-Jung; Ren, Nanqi

2015-03-01

160

Semi-empirical estimation of organic compound fugacity ratios at environmentally relevant system temperatures.  

PubMed

Fugacity ratios of organic compounds are used to calculate (subcooled) liquid properties, such as solubility or vapour pressure, from solid properties and vice versa. They can be calculated from the entropy of fusion, the melting temperature, and heat capacity data for the solid and the liquid. For many organic compounds, values for the fusion entropy are lacking. Heat capacity data are even scarcer. In the present study, semi-empirical compound class specific equations were derived to estimate fugacity ratios from molecular weight and melting temperature for polycyclic aromatic hydrocarbons and polychlorinated benzenes, biphenyls, dibenzo[p]dioxins and dibenzofurans. These equations estimate fugacity ratios with an average standard error of about 0.05 log units. In addition, for compounds with known fusion entropy values, a general semi-empirical correction equation based on molecular weight and melting temperature was derived for estimation of the contribution of heat capacity differences to the fugacity ratio. This equation estimates the heat capacity contribution correction factor with an average standard error of 0.02 log units for polycyclic aromatic hydrocarbons, polychlorinated benzenes, biphenyls, dibenzo[p]dioxins and dibenzofurans. PMID:19304312

van Noort, Paul C M

2009-06-01

161

Correlation Between Peak-to-Average Power Ratio and Four-Wave Mixing in Optical OFDM Systems  

Microsoft Academic Search

Coherent optical orthogonal frequency-division multiplexed (OFDM) systems have been shown to be vulnerable to fiber nonlinearity, four-wave mixing (FWM) in particular. Consequently, transmission of OFDM symbols with a low peak-to-average power ratio (PAR) is widely recommended. In this paper, we examine the correlation between PAR and the intensity of light generated through FWM for two different systems. It is demonstrated

Vladimir Pechenkin; Ivan J. Fair

2009-01-01

162

Aripiprazole-Cyclodextrin Binary Systems for Dissolution Enhancement: Effect of Preparation Technique, Cyclodextrin Type and Molar Ratio  

PubMed Central

Objective(s): The aim of this work was to investigate the effect of the natural and the chemically modified form of cyclodextrins namely; ?-cyclodextrin (?-CD) and hydroxypropyl-?-cyclodextrin (HP-?-CD) respectively on the solubility and dissolution rate of aripiprazole; an antipsychotic medication showing poor aqueous solubility. Materials and Methods: Phase solubility of aripiprazole with the studied CDs and the complexation efficiency values (CE) which reflect the solubilizing power of the CDs towards the drug was performed. Solid binary systems of aripiprazole with CDs were prepared by kneading, microwave irradiation and freeze-drying techniques at 1:1 and 1:2 (drug to CD) molar ratios. Drug-CD physical mixtures were also prepared in the same molar ratios for comparison. The dissolution of aripiprazole-binary systems was carried out to select the most appropriate CD type, molar ratio and preparation technique. Results: Phase solubility study indicated formation of higher order complexes and the complexation efficiency values was higher for HP-?-CD compared to ?-CD. Drug dissolution study revealed that aripiprazole dissolution was increased upon increasing the CD molar ratio and, the freeze-drying technique was superior to the other studied methods especially when combined with the HP-?-CD. The cyclodextrin type, preparation technique and molar ratio exhibited statistically significant effect on the drug dissolution at P? 0.05. Conclusion: The freeze-dried system prepared at molar ratio 1:2 (drug: CD) can be considered as efficient tool for enhancing aripiprazole dissolution with the possibility of improving its bioavailability. PMID:24570827

M. Badr-Eldin, Shaimaa; A. Ahmed, Tarek; R Ismail, Hatem

2013-01-01

163

Real-Time Measurement of Oil Circulation Ratio in CO2 Heat Pump System Using Optical Method  

NASA Astrophysics Data System (ADS)

The lubricating oil in the refrigerant flow in a CO2 heat pump system has a great influence on cycle performance. In order to measure the OCR (Oil circulation ratio), a mixing chamber and a visual vessel were installed at the outlet of the gas-cooler. By mixing the oil and refrigerant, the liquid mixture of oil and refrigerant becomes cloudy at the outlet of the gas-cooler. By measuring the infrared ray transmittance of the oil-refrigerant liquid mixture, it was found that the transmittance decreases with an increase in the oil circulation ratio. For this reason, it is found that, in spite of immiscible refrigerant and oil, the measurement of the oil circulation ratio is possible by measuring the transmittance of infrared ray at the outlet of the gas-cooler.

Takigawa, Ryusuke; Shimizu, Takao; Matsusaka, Yukio; Gao, Lei; Honda, Tomohiro

164

Technique to measure CO 2 mixing ratio in small flasks with a bellows\\/IRGA system  

Microsoft Academic Search

We developed a laboratory method to obtain high precision CO2 mixing ratios in air samples contained in 100ml glass flasks, which involves extracting air from the flask into a pre-evacuated manifold containing a variable-volume metal bellows. Compressed air from the bellows is then routed to a non-dispersive infrared gas analyzer (IRGA). Tests indicate that this configuration has an overall accuracy

D. R. Bowling; C. S. Cook; J. R. Ehleringer

2001-01-01

165

Explicit-explicit subcycling with non-integer time step ratios for structural dynamic systems  

NASA Technical Reports Server (NTRS)

An explicit-explicit subcycling procedure for the finite element analysis of structural dynamics is developed. This procedure has relaxed the usual constraint of requiring integer time step ratios for adjacent nodal groups. This allows for greater advantage to be taken of local stability criteria, and thus improves the efficiency of the explicit time integrator. Example problems are included to demonstrate the accuracy and stability of the method.

Neal, Mark O.; Belytschko, Ted

1989-01-01

166

Signal-to-Noise Ratio in Doppler Radar System for Heart and Respiratory Rate Measurements  

Microsoft Academic Search

A CMOS Doppler radar sensor has been developed and used to measure motion due to heart and respiration. The quadrature direct-conversion radar transceiver has been fully integrated in 0.25-mum CMOS, the baseband analog signal conditioning has been developed on a printed circuit board, and digital signal processing has been performed in Matlab. The theoretical signal-to-noise ratio (SNR) is derived based

Amy D. Droitcour; Olga Boric-Lubecke; Gregory T. A. Kovacs

2009-01-01

167

New theoretical models and ratio imaging techniques associated with the NASA earth resources spectral information system  

NASA Technical Reports Server (NTRS)

Four independent investigations are reported; in general these are concerned with improving and utilizing the correlation between the physical properties of natural materials as evidenced in laboratory spectra and spectral data collected by multispectral scanners. In one investigation, two theoretical models were devised that permit the calculation of spectral emittance spectra for rock and mineral surfaces of various particle sizes. The simpler of the two models can be used to qualitatively predict the effect of texture on the spectral emittance of rocks and minerals; it is also potentially useful as an aid in predicting the identification of natural atmospheric aerosol constituents. The second investigation determined, via an infrared ratio imaging technique, the best pair of infrared filters for silicate rock-type discrimination. In a third investigation, laboratory spectra of natural materials were compressed into 11-digit ratio codes for use in feature selection, in searches for false alarm candidates, and eventually for use as training sets in completely automatic data processors. In the fourth investigation, general outlines of a ratio preprocessor and an automatic recognition map processor are developed for on-board data processing in the space shuttle era.

Vincent, R. K.

1974-01-01

168

Note: An advanced in situ diagnostic system for characterization of electric propulsion thrusters and ion beam sources  

Microsoft Academic Search

We present an advanced diagnostic system for in situ characterization of electric propulsion thrusters and ion beam sources. The system uses a high-precision five-axis positioning system with a modular setup and the following diagnostic tools: a telemicroscopy head for optical imaging, a triangular laser head for surface profile scanning, a pyrometer for temperature scanning, a Faraday probe for current density

C. Bundesmann; M. Tartz; F. Scholze; H. J. Leiter; F. Scortecci; R. Y. Gnizdor; H. Neumann

2010-01-01

169

Supplementary Excitation Controller design to enhance system Damping Ratio using an innovative swarm intelligence algorithm  

Microsoft Academic Search

With the increasing Complexity of Modern Interconnected Power Systems, Low Frequency inertial Oscillations after a disturbance in a Power System are becoming one of the major problem. This paper provides a systematic approach for designing a Supplementary Excitation Controller to damp the Low frequency oscillations observed in the system using an Innovative Particle Swarm Optimization (PSO) Algorithm. In Power systems,

R. Shivakumar; R. Lakshmipathi; Y. Suresh

2009-01-01

170

The effect of expansion-ratio limitations on positive-displacement, total-flow geothermal power systems  

SciTech Connect

Combined steam-turbine/positive-displacement engine (PDE) geothermal power systems are analyzed thermodynamically and compared with optimized reference flash-steam plants. Three different configurations of combined systems are considered. Treated separately are the cases of self-flowing and pumped wells. Two strategies are investigated that help overcome the inherent expansion-ratio limitation of PDE's: pre-flashing and pre-mixing. Parametrically-obtained results show the required minimum PDE efficiency for the combined system to match the reference plant for various sets of design conditions.

DiPippo, R.

1982-02-01

171

influence of concentration and mannuronate/guluronate [correction of gluronate] ratio on steady flow properties of alginate aqueous systems.  

PubMed

Steady flow properties were measured at various concentrations for aqueous systems of alignates with different mannuronate/gluronate (M/G) ratios using a cone-plate type rheometer. The flow curve (a plot of shear stress vs. shear rate) shows a plateau region, which is ascribed to a heterogeneous structure, at low shear rate. This plateau region is more noticeable in the G-rich systems than in the M-rich systems. On the other hand, the flow curves for the systems with the same molecular weight but different M/G ratios are congruent in the high shear rate region. The zero shear viscosity can be reduced by the segment contact parameter, cMw, for the alginates with the same M/G ratio but different molecular weights. The zero shear viscosity is proportional to cMw in a low concentration region and is proportional to (cMw)3.4 at relatively high concentrations. The critical value of cMw for which the zero shear viscosity changes from proportionality with cMw to proportionality with (cMw)3.4 is ca. 900. PMID:1306367

Matsumoto, T; Kawai, M; Masuda, T

1992-01-01

172

An analytical system for determining delta17O in CO2 using continuous flow-isotope ratio MS.  

PubMed

We developed a simple measurement system for delta17O in nanomole quantities of CO2 using continuous flow isotope ratio mass spectrometry (CF-IRMS). The analytical system consisted of a sample injection system, a helium-purged CO2 purification line, a capillary GC, a combustion unit, and CF-IRMS. A unique feature of the system is that we use molecular CO2 to determine the isotopic compositions including delta17O. The delta17O of CO2 in a sample is calculated from the mass ratios of both 45/44 and 46/44 of two different kinds of CO2, which have been purified quantitatively from different aliquots of a sample. While one aliquot (rCO2) flows into IRMS directly, the other (eCO2) flows through a CuO unit (900 degrees C) prior to injection into IRMS, to exchange oxygen atoms in the sample CO2 molecules with those in CuO for which we can assume Delta17O = 0. In our system, we introduce both rCO2 and eCO2 alternately to IRMS repeatedly by using an automatic multianalytical system to improve analytical precision statistically. The standard deviation of 0.35 per thousand for Delta17O can be realized using as little as 8.7 nmol CO2 in a approximately 3-h analysis. Based on this system, we have quantified delta17O in the stratospheric CO2 over Japan. PMID:16013867

Kawagucci, Shinsuke; Tsunogai, Urumu; Kudo, Shingo; Nakagawa, Fumiko; Honda, Hideyuki; Aoki, Shuji; Nakazawa, Takakiyo; Gamo, Toshitaka

2005-07-15

173

Collision induced coherence in plasma and Branching Ratio in multilevel system  

E-print Network

This work has been stimulated by the quenching of spontaneous emission in an optically thin high-density plasma reported by Suckewer and coworkers [Phys.Rev.Lett. 60,1122(1988)]. Our work is based on the collision-induced coherence of two decay channels along two optical transitions.The quantum interference of pumping processes creates the dark state and the more atoms are pumped in this collision-induced dark state the stronger the suppression of the spontaneous emission. The efficiency of this suppression is quantified by putting it in comparison with the spontaneous emission on the ultraviolet transition which proceeds in a regular fashion. The branching ratio of these two(visible and ultraviolet) transitions is introduced as the effective measure of the degree of the suppression of the spontaneous emission on the visible transition. Our preliminary calculations show that a significant decrease of the branching ratio with increase of electron densities is reproduced in the theory. More experiments and more elaborated theories are needed to conclude about the role of quantum coherence and interference in such manifestly incoherent media as plasmas.

Dong Sun; Victor V. Kozlov; Yuri V. Rostovtsev; Marlan O. Scully

2012-09-21

174

Companding scheme for peak-to-average power ratio reduction in optical orthogonal frequency division multiplexing systems  

NASA Astrophysics Data System (ADS)

A companding method for peak-to-average power ratio (PAPR) reduction in optical orthogonal frequency division multiplexing systems has been proposed and simulated. The proposed scheme is based on the modified hyperbolic tangent transform, which can enlarge the small signals and compress the large signals while keeping the average power invariant. Simulation results verify that the proposed companding scheme can markedly decrease the PAPR, and a good bit error rate performance is obtained.

Wang, Dong; Zou, Nianyu; Cui, Gaofeng; Yang, Yi; Namihira, Yoshinori; Zhang, Yinghai

2012-11-01

175

Wind tunnel tests of high-lift systems for advanced transports using high-aspect-ratio supercritical wings  

NASA Technical Reports Server (NTRS)

The wind tunnel testing of an advanced technology high lift system for a wide body and a narrow body transport incorporating high aspect ratio supercritical wings is described. This testing has added to the very limited low speed high Reynolds number data base for this class or aircraft. The experimental results include the effects on low speed aerodynamic characteristics of various leading and trailing edge devices, nacelles and pylons, ailerons, and spoilers, and the effects of Mach and Reynolds numbers.

Allen, J. B.; Oliver, W. R.; Spacht, L. A.

1982-01-01

176

On the Analysis of Peak-to-Average Ratio (PAR) for IS95 and CDMA2000 Systems  

Microsoft Academic Search

Abstract—Peak-to-average ratio (PAR) of a signal is an im- portant parameter to a linear amplifier because it determines the backoff factor needed,to be applied to the amplifier in order to avoid clipping and,hence spectral regrowth. In this paper, we analyzed the PAR of the downlink direct code-division multiple-access (DS-CDMA) signal for the IS-95 (2G) and the CDMA2000 (3G) systems. Both

Vincent K. N. Lau

2000-01-01

177

Average of peak-to-average ratio (PAR) of IS95 and CDMA2000 systems-single carrier  

Microsoft Academic Search

Peak-to-average ratio (PAR) of a signal is an impor- tant parameter. It determines the input backoff factor of the ampli- fier to avoid clipping and spectral regrowth. In this letter, we ana- lyze and compose the PAR of the downlink signal for IS95 and the CDMA2000 single-carrier systems. It is found that PAR of the trans- mitted signal depends on

Vincent K. N. Lau

2001-01-01

178

On the analysis of peak-to-average ratio (PAR) for IS95 and CDMA2000 systems  

Microsoft Academic Search

Peak-to-average ratio (PAR) of a signal is an important parameter to a linear amplifier because it determines the backoff factor needed to be applied to the amplifier in order to avoid clipping and hence spectral regrowth. In this paper, we analyzed the PAR of the downlink direct code-division multiple-access (DS-CDMA) signal for the IS-95 (2G) and the CDMA2000 (3G) systems.

Vincent K. N. Lau

2000-01-01

179

An analysis of CCD camera noise and its effect on pressure sensitive paint instrumentation system signal-to-noise ratio  

Microsoft Academic Search

Quantitative pressure measurements can be acquired by pressure sensitive paint (PSP) instrumentation systems incorporating charge-coupled devices (CCD) for PSP photoluminescence image detection. However, intrinsic CCD noise corrupts the PSP image, manifesting in erroneous measurements of pressure and the corresponding coefficient of pressure (Cp). This manifestation is analyzed and quantified in terms of PSP image signal-to-noise ratio (SNR). The image acquisition

D. R. Mendoza

1997-01-01

180

Flow pattern exchange in the Taylor-Couette system with a very small aspect ratio.  

PubMed

Numerical investigation is carried out on the flow pattern exchanges found in Taylor-Couette flows between two concentric rotating cylinders. The inner cylinder rotates while the outer cylinder and both end walls are stationary. The aspect ratio (column length/gap width) is small, and its range is from 0.5 to 1.6. Previous experimental results for this range of the aspect ratio showed that the steady flow patterns are classified into three groups: the normal two-cell mode, anomalous one-cell mode and twin-cell mode. All modes found by experiments are predicted in the present numerical calculation. Besides these three flow modes, an unsteady mode is predicted, which is time dependent and fully developed. The existence of the unsteady mode is also confirmed by our experiments. When the inner cylinder starts to rotate from rest, vortices at the corners of the inner cylinder and both end walls develop, and they induce the normal two-cell mode. The flow of the anomalous one-cell mode or twin-cell mode appears after an abrupt breakdown of symmetric two-cell mode flows. During the gradual deceleration of the inner cylinder, the transitions of flow modes occur. We observed mode transitions between the normal two-cell mode and anomalous one-cell mode and mode transitions from the twin-cell mode to the normal two-cell mode, anomalous one-cell mode, and unsteady mode. The critical loci where these mode transitions appear are determined. The numerical confirmation of the twin-cell mode is a different result obtained in the present study. PMID:11909243

Furukawa, Hiroyuki; Watanabe, Takashi; Toya, Yorinobu; Nakamura, Ikuo

2002-03-01

181

Permanence and periodic solutions for an impulsive reaction-diffusion food-chain system with ratio-dependent functional response  

NASA Astrophysics Data System (ADS)

An impulsive reaction-diffusion periodic food-chain system with ratio-dependent functional response is investigated in the present paper. Sufficient conditions for the ultimate boundedness and permanence of the food-chain system are established based on the comparison theory of differential equation and upper and lower solution method. By constructing appropriate auxiliary function, the conditions for the existence of a unique globally stable positive periodic solution are also obtained. Some numerical examples are presented to verify our results. A discussion is given in the end of the paper.

Liu, Zijian; Zhong, Shouming; Liu, Xiaoyun

2014-01-01

182

Modeling percolation in high-aspect-ratio fiber systems. II. The effect of waviness on the percolation onset  

NASA Astrophysics Data System (ADS)

The onset of electrical percolation in nanotube-reinforced composites is often modeled by considering the geometric percolation of a system of penetrable, straight, rigid, capped cylinders, or spherocylinders, despite the fact that embedded nanotubes are not straight and do not penetrate one another. In Part I of this work we investigated the applicability of the soft-core model to the present problem, and concluded that the hard-core approach is more appropriate for modeling electrical percolation onset in nanotube-reinforced composites and other high-aspect-ratio fiber systems. In Part II, we investigate the effect of fiber waviness on percolation onset. Previously, we studied extensively the effect of joint morphology and waviness in two-dimensional nanotube networks. In this work, we present the results of Monte Carlo simulations studying the effect of waviness on the percolation threshold of randomly oriented fibers in three dimensions. The excluded volumes of fibers were found numerically, and relationships between these and percolation thresholds for two different fiber morphologies were found. We build on the work of Part I, and extend the results of our soft-core, wavy fiber simulations to develop an analytical solution using the more relevant hard-core model. Our results show that for high- aspect-ratio fibers, the generally accepted inverse proportionality between percolation threshold and excluded volume holds, independent of fiber waviness. This suggests that, given an expression for excluded volume, an analytical solution can be derived to identify the percolation threshold of a system of high-aspect-ratio fibers, including nanotube-reinforced composites. Further, we show that for high aspect ratios, the percolation threshold of the wavy fiber networks is directly proportional to the analytical straight fiber solution and that the constant of proportionality is a function of the nanotube waviness only. Thus the onset of percolation can be adequately modeled by applying a factor based on fiber geometry to the analytical straight fiber solution.

Berhan, L.; Sastry, A. M.

2007-04-01

183

The Role of Boron-Chloride and Noble Gas Isotope Ratios in TVZ Geothermal Systems  

SciTech Connect

The model of the geothermal system in which deep circulating groundwater containing noble gases, at air saturated water concentrations, mixes with hot fluids of mantle origin at depth, is extended to include the effect of interaction of the ascending fluid with both solid and gaseous phases of basement (or other) rocks en route to the surface. It is demonstrated that this interaction is responsible for most of the CO{sub 2} in the Taupo Volcanic Zone (TVZ) geothermal systems. It is proposed that the modeling of this interaction might be accomplished by techniques similar to those used for the understanding of the oxygen isotope shift found in geothermal systems. The water rock interaction experiments of Ellis and Mahon (1964, 1967) provides some data on the kinetic rates for B and Cl dissolution from rocks likely to be encountered in the geothermal system, but further information on the behavior of B may be needed. If these problems can be overcome this modeling technique has promise for the estimation of the recharge of geothermal systems and hence the sustainability of these systems.

Hulston, J.R.

1995-01-01

184

DEEP, LOW MASS RATIO OVERCONTACT BINARY SYSTEMS. XIII. DZ PISCIUM WITH INTRINSIC LIGHT VARIABILITY  

SciTech Connect

New multi-color photometry for the eclipsing binary DZ Psc was performed in 2011 and 2012 using the 85 cm telescope at the Xinglong Station of the National Astronomical Observatories of China. Using the updated Wilson-Devinney (W-D) code, we deduced two sets of photometric solutions. The overcontact degree is f = 89.7({+-} 1.0)%, identifying DZ Psc as a deep, low mass ratio overcontact binary. The asymmetric light curves (i.e., LC{sub 2} in 2012) were modeled by a hot spot on the primary star. Based on all of the available light minimum times, we discovered that the orbital period of DZ Psc may be undergoing a secular period increase with a cyclic variation. The modulated period and semi-amplitude of this oscillation are P{sub mod} = 11.89({+-} 0.19) yr and A = 0.0064({+-} 0.0006) days, which may be possibly attributed to either cyclic magnetic activity or light-time effect due to the third body. The long-term period increases at a rate of dP/dt=+7.43({+-}0.17) Multiplication-Sign 10{sup -7} days yr{sup -1}, which may be interpreted as conserved mass transfer from the less massive component to the more massive one. With mass transferring, DZ Psc will finally merge into a rapid-rotation single star when J{sub spin}/J{sub orb} > 1/3.

Yang, Y.-G.; Dai, H.-F. [School of Physics and Electronic Information, Huaibei Normal University, 235000 Huaibei, Anhui Province (China); Qian, S.-B. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, 650011 Kunming (China); Zhang, L.-Y. [Department of Physics, College of Science, Guizhou University, 550025 Guiyang (China); Soonthornthum, B., E-mail: yygcn@163.com, E-mail: qsb@ynao.ac.cn [National Astronomical Research Institute of Thailand/Ministry of Science and Technology, Bangkok (Thailand)

2013-08-01

185

California bearing ratio behavior of soil-stabilized class F fly ash systems  

SciTech Connect

Fly ash is a finely divided mineral residue resulting from the combustion of coal in power plants that occupies large extents of land and also causes environmental problems. Hence, concerted attempts are being made to effectively use fly ash in an environmentally friendly way instead of dumping. Several studies have been carried out for its bulk utilization, such as its addition to improve the California bearing ratio (CBR) of soil in roads and embankments. But a thorough mixing of fly ash with soil may not be possible in the field. Hence a study has been carried out on the CBR behavior of black cotton soil and Raichur fly ash (which is class F) in layers and compared with the same in mixes. The results show that the CBR values of soil-fly ash mixes are better than layers, as expected. To improve the strength of layers, cement is used as an additive to fly ash. The results show that black cotton soil can be improved with stabilized fly ash, solving its strength problem as well as the disposal problem of fly ash.

Leelavathamma, B.; Mini, K.M.; Pandian, N.S. [Indian Institute for Science, Bangalore (India). Dept. for Civil Engineering

2005-11-01

186

Modeling percolation in high-aspect-ratio fiber systems. I. Soft-core versus hard-core models.  

PubMed

Numerical and analytical studies of the onset of percolation in high-aspect-ratio fiber fiber systems such as nanotube reinforced polymers available in the literature have consistently modeled fibers as penetrable, straight, capped cylinders, also referred to as spherocylinders. In reality, however, fibers of very high-aspect ratio embedded in a polymer do not come into direct physical contact with each other, let alone exhibit any degree of penetrability. Further, embedded fibers of very high-aspect ratio are often actually wavy, rather than straight. In this two-part paper we address these critical differences between known physical systems, and the presently used spherocylinder percolation model. In Paper I we evaluate the effect of allowing penetration of the model fibers on simulation results by comparing the soft-core and the hard-core approaches to modeling percolation onset. We use Monte Carlo simulations to investigate the relationship between percolation threshold and excluded volume for both modeling approaches. Our results show that the generally accepted inverse proportionality between percolation threshold and excluded volume holds for both models. We further demonstrate that the error introduced by allowing the fibers to intersect is non-negligible, and is a function of both aspect ratio and tunneling distance. Thus while the results of both the soft-core model and hard-core assumptions can be matched to select experimental results, the hard-core model is more appropriate for modeling percolation in nanotubes-reinforced composites. The hard-core model can also potentially be used as a tool in calculating the tunneling distance in composite materials, given the fiber morphology and experimentally derived electrical percolation threshold. In Paper II we investigate the effect of the waviness of the fibers on the onset of percolation in fiber reinforced composites. PMID:17500878

Berhan, L; Sastry, A M

2007-04-01

187

Evaluation of the Association of Sleep Apnea-Related Systemic Inflammation with CRP, ESR, and Neutrophil-to-Lymphocyte Ratio  

PubMed Central

Background Obstructive sleep apnea syndrome (OSAS) is characterized by cyclic episodes of hypoxemia and reoxygenation. It has been suggested that OSAS is associated with chronic inflammation within the microvasculature. This low-grade inflammation may play a role in the pathophysiology of OSAS-related comorbidities. Evaluation of the inflammatory markers may predict the degree of the systemic inflammation and this may be a prognostic factor for future adverse events such as cardiovascular risks. Proinflammatory cytokines have been extensively studied in sleep-disordered breathing. Neutrophil-to-lymphocyte ratio is a recently described indicator of systemic inflammation, but it has not been studied in OSAS patients. In this study we aimed to evaluate the easily measurable parameters of systemic inflammation in these patients. We conducted this study to examine the association among OSAS and C- reactive protein, erythrocyte sedimentation rate, and neutrophil-to-lymphocyte ratio. Material/Methods OSAS patients who underwent overnight polysomnography were studied retrospectively. They were divided into 4 groups: control, mild, moderate, and severe OSAS patients. Blood test results and inflammatory markers were compared between the groups. One-way ANOVA and Kruskall-Wallis H test were used for statistical analysis. Results A total of 147 patients were included in the study. No differences in evaluated inflammatory markers were observed among the 4 groups. Conclusions Evaluation of the OSAS-related systemic inflammation is not likely to be possible by CRP, ESR, or neutrophil-to-lymphocyte ratio measurements. These markers do not seem to be associated with the degree of the upper airway obstruction. PMID:25686632

Korkmaz, Mukadder; Korkmaz, Hakan; Küçüker, Fatma; Ayy?ld?z, Sema Nur; Çankaya, Soner

2015-01-01

188

Vasopressin Decreases Pulmonary-to-Systemic Vascular Resistance Ratio in a Porcine Model of Severe Hemorrhagic Shock.  

PubMed

Vasopressors are gaining renewed interest as treatment adjuncts in hemorrhagic shock. The ideal vasoconstrictor will increase systemic blood pressure without increasing pulmonary vascular resistance (PVR), which hinders pulmonary perfusion and exacerbates hypoxemia. However, the selectivity of pressors for pulmonary versus systemic vasoconstriction during hemorrhage has not been characterized. The purpose of this study was to test the hypothesis that vasopressin (VP) has distinct effects on pulmonary versus systemic hemodynamics, unlike the catecholamine vasopressors norepinephrine (NE) and phenylephrine (PE). Anesthetized and ventilated pigs were assigned to resuscitation with saline only (n = 7) or saline with VP (n = 6), NE (n = 6), or PE (n = 6). Animals were hemorrhaged to a target volume of 30 mL/kg and a mean arterial pressure of 35 mmHg. One hour after the start of hemorrhage, animals were resuscitated with saline up to one shed blood volume, followed by either additional saline or a vasopressor. Hemodynamics and oxygenation were measured hourly for 4 h after the start of hemorrhage. Vasopressin increased systemic vascular resistance (SVR) while sparing the pulmonary vasculature, leading to a 45% decrease in the PVR/SVR ratio compared with treatment with PE. Conversely, NE induced pulmonary hypertension and led to an increased PVR/SVR ratio associated with decreased oxygen saturation. Phenylephrine and crystalloid had no significant effect on the PVR/SVR ratio. Sparing of pulmonary vasoconstriction occurs only with VP, not with administration of crystalloid or catecholamine pressors. The ability of VP to maintain blood oxygenation indicates that VP may prevent hypoxemia in the management of hemorrhagic shock. PMID:25565637

Sarkar, Joy; Golden, Patrick J; Kajiura, Lauren N; Murata, Lee-Ann M; Uyehara, Catherine F T

2015-05-01

189

Selenium stable isotope ratios in California agricultural drainage water management systems  

USGS Publications Warehouse

Selenium stable isotope ratios are known to shift in predictable ways during various microbial, chemical, and biological processes, and can be used to better understand Se cycling in contaminated environments. In this study we used Se stable isotopes to discern the mechanisms controlling the transformation of oxidized, aqueous forms of Se to reduced, insoluble forms in sediments of Se-affected environments. We measured 80Se/76Se in surface waters, shallow ground waters, evaporites, digested plants and sediments, and sequential extracts from several sites where agricultural drainage water is processed in the San Joaquin Valley of California. Selenium isotope analyses of samples obtained from the Tulare Lake Drainage District flow-through wetland reveal small isotopic contrasts (mean difference 0.7%o) between surface water and reduced Se species in the underlying sediments. Selenium in aquatic macrophytes was very similar isotopically to the NaOH and Na2SO3 sediment extracts designed to recover soluble organic Se and Se(O), respectively. For the integrated on-farm drainage management sites, evaporite salts were slightly (approximately 0.6%o) enriched in the heavier isotope relative to the inferred parent waters, whereas surface soils were slightly (approximately 1.4%o) depleted. Bacterial or chemical reduction of Se(VI) or Se(IV) may be occurring at these sites, but the small isotopic contrasts suggest that other, less isotopically fractionating mechanisms are responsible for accumulation of reduced forms in the sediments. These findings provide evidence that Se assimilation by plants and algae followed by deposition and mineralization is the dominant transformation pathway responsible for accumulation of reduced forms of Se in the wetland sediments.

Herbel, M.J.; Johnson, T.M.; Tanji, K.K.; Gao, S.; Bullen, T.D.

2002-01-01

190

Evaluation of the water-effect ratio procedure for metals in a riverine system  

SciTech Connect

Site-specific metal standards were determined for a part of the lower Lehigh River using the US Environmental Protection Agency`s water-effect ratio (WER) procedure. The WERs were based on laboratory and site water testing of the species Ceriodaphnia dubia and Pimephales promelas (fathead minnow) and five metals (copper, cadmium, lead, silver, and zinc) during four different months. Both species generally exhibited similar patterns in WERs. The greatest variability between the two species was observed for copper, silver, and lead. Ceriodaphnia yielded a lower mean WER than the fathead minnow for lead and zinc and WERs similar to those of the fathead minnow for copper, cadmium, and silver. The species more sensitive to a given metal did not always exhibit a higher WER, as had been previously assumed. A comparison of final WER calculations indicated that the geometric mean WER was typically higher than the final WER obtained using the 1994 guidance. For most metals, site water toxicity was reduced due to nonacutely toxic dissolved metal. Copper yielded the highest final WER regardless of the calculation method used. Regression analyses indicated that the copper WER was directly related, and the cadmium WER inversely related, to effluent concentration. Copper, lead, and silver WERs were related to site water pH. Cadmium and lead WERs were related to pH and dissolved solids. Zinc WERs were unrelated to any of the water quality variables measured and were similar among site water samples. The results suggest it is prudent to use two species in WER testing and different site water samples to derive a final WER, particularly at sites that are not effluent dominated.

Diamond, J.M. [Tetra Tech, Inc., Owings Mills, MD (United States); Koplish, D.E.; McMahon, J. III; Rost, R. [Bureau of Water Resources, Allentown, PA (United States)

1997-03-01

191

Lightning Ratios  

NSDL National Science Digital Library

Using satellites and ground-based detection instruments, researchers have now mapped out lightning ratios for the continental United States. The Lightning Ratios site, from Space Science News (NASA), provides recent data in the form of a vibrant color map (.pdf or .jpg) of cloud-to-cloud lightning to cloud-to-ground lightning over the continental United States.

192

Robustness analysis of likelihood ratio score fusion rule for multimodal biometric systems under spoof attacks  

Microsoft Academic Search

Recent works have shown that, contrary to a common belief, multi-modal biometric systems may be “forced” by an impostor by submitting a spoofed biometric replica of a genuine user to only one of the matchers. Although those results were obtained under a worst-case scenario when the attacker is able to replicate the exact appearance of the true biometric, this raises

Zahid Akhtar; Giorgio Fumera; Gian Luca Marcialis; Fabio Roli

2011-01-01

193

Peak-to-Average Power Ratio analysis in MIMO systems Basel Rihawi and Yves Louet  

E-print Network

- ministic signal in case of SISO system. 2. PAPR and PMEPR definitions for SISO-single carrier The peak, for a large number of samples per symbol (more than Nyquist frequency sampling) and large constellation size, the computational effort in finding PAPR and PMEPR will become large [4]. 2.1. Definition of PMEPR The PMEPR is used

Boyer, Edmond

194

Research on modern testing technique of optical system magnifying ratio based on CCD imaging theory  

Microsoft Academic Search

The paper discusses a new kind of modern testing method used in magnification of telescopic optical system, which applied the technique of photoelectric imaging creation automatically based on DLP theory and the technique of collecting image based on CCD imaging theory. This method simplifies customary measuring process, realizes objective and automatic measuring, and avoids subjective error which artificial factor leads

Lixia Shi; Chang Zeng

2005-01-01

195

36Cl/Cl ratios in geothermal systems: preliminary measurements from the Coso Field  

SciTech Connect

The {sub 36}Cl/Cl isotopic composition of chlorine in geothermal systems can be a useful diagnostic tool in characterizing hydrologic structure, in determining the origins and age of waters within the systems, and in differentiating the sources of chlorine (and other solutes) in the thermal waters. The {sub 36}Cl/Cl values for several geothermal water samples and reservoir host rock samples from the Coso, California geothermal field have been measured for these purposes. The results indicate that most of the chlorine is not derived from the dominant granitoid that host the geothermal system. If the chlorine was originally input into the Coso subsurface through meteoric recharge, that input occurred at least 1-1.25 million years ago. The results suggest that the thermal waters could be connate waters derived from sedimentary formations, presumably underlying and adjacent top the granitic rocks, which have recently migrated into the host rocks. Alternatively, most of the chlorine but not the water, may have recently input into the system from magmatic sources. In either case, the results indicate that most of the chlorine in the thermal waters has existed within the granitoid host rocks for no more than about 100,00-200,00 years. this residence time for the chlorine is similar to residence times suggested by other researchers for chlorine in deep groundwaters of the Mono Basin north of the Coso field.

Nimz, G.J.; Moore, J.N.; Kasameyer, P.W.

1997-07-01

196

A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system  

Microsoft Academic Search

The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield

Azizah Endut; A. Jusoh; N. Ali; W. B. Wan Nik; A. Hassan

2010-01-01

197

Signal to noise ratio improvement in lidar systems incorporating neodymium doped optical fiber preamplifiers  

Microsoft Academic Search

A continuous-wave-only micron lidar (light detection and ranging) system is modeled to examine the potential benefits of incorporating a neodymium-doped optical fiber amplifier in the path of the returning optical signal. The spectroscopic theory of a four-level dopant is discussed to introduce factors involved in pumping a doped fiber to use as a fiber amplifier. Spontaneous emission effects are considered.

Michael S. Salisbury; Paul F. McManamon; Bradley D. Duncan

1992-01-01

198

The ratio between radiative and nonradiative energy transfer in lasing systems  

NASA Astrophysics Data System (ADS)

The contributions of radiative and nonradiative energy transfer are estimated for the systems rhodamine-oxazine, rhodamine-cresyl violet, and rhodamine-oxazine under conditions of laser excitation in the absence of donor generation. The rate constants of radiative and nonradiative energy transfer are also investigated as a function of the acceptor concentration. The results obtained are supported by experimental data on the relationship between donor luminescence polarization and acceptor concentration.

Levin, M. B.; Reva, M. G.; Rodchenkova, V. V.; Uzhinov, B. M.

1986-06-01

199

A five-collector system for the simultaneous measurement of argon isotope ratios in a static mass spectrometer  

USGS Publications Warehouse

A system is described that utilizes five separate Faraday-cup collector assemblies, aligned along the focal plane of a mass spectrometer, to collect simultaneous argon ion beams at masses 36-40. Each collector has its own electrometer amplifier and analog-to-digital measuring channel, the outputs of which are processed by a minicomputer that also controls the mass spectrometer. The mass spectrometer utilizes a 90?? sector magnetic analyzer with a radius of 23 cm, in which some degree of z-direction focussing is provided for all the ion beams by the fringe field of the magnet. Simultaneous measurement of the ion beams helps to eliminate mass-spectrometer memory as a significant source of measurement error during an analysis. Isotope ratios stabilize between 7 and 9 s after sample admission into the spectrometer, and thereafter changes in the measured ratios are linear, typically to within ??0.02%. Thus the multi-collector arrangement permits very short extrapolation times for computation of initial ratios, and also provides the advantages of simultaneous measurement of the ion currents in that errors due to variations in ion beam intensity are minimized. A complete analysis takes less than 10 min, so that sample throughput can be greatly enhanced. In this instrument, the factor limiting analytical precision now lies in short-term apparent variations in the interchannel calibration factors. ?? 1981.

Stacey, J.S.; Sherrill, N.D.; Dalrymple, G.B.; Lanphere, M.A.; Carpenter, N.V.

1981-01-01

200

A simple optical system to optimize a high depth to width aspect ratio applied to a positive photoresist lithography process  

NASA Astrophysics Data System (ADS)

The fabrication of micro electro mechanical systems by electrodeposition inside resist moulds has provided much interest in recent years. In this paper, we propose a method to optimize the lithography process of a thick positive photoresist. This technique is based on the variation of transparency of the photoresist during exposure. During exposure the absorption of the light-sensitive compound decreases due to its conversion into indene carboxylic acid. A very good aspect ratio (height:width) of up to 10:1 and high edge steepness 0960-1317/7/3/009/img1 has been obtained from one coat and one UV exposure.

Conédéra, V.; Fabre, N.; Dilhan, M.

1997-09-01

201

BRIEF COMMUNICATIONS: Ratio of radiative to nonradiative energy transfer in lasing systems  

NASA Astrophysics Data System (ADS)

An estimate is obtained of the contributions of radiative and nonradiative energy transfer processes in rhodamine 6G-oxazine 17, rhodamine 6G-cresyl violet, and rhodamine S-oxazine 17 systems subjected to laser excitation in the absence of donor Iasing. A study is made of the dependences of the rate constants of radiative and nonradiative energy transfer processes on the acceptor concentration. Theoretical estimates are supported by experimental dependences of the degree of polarization of the donor luminescence on the acceptor concentration.

Levin, M. B.; Reva, M. G.; Rodchenkova, V. V.; Uzhinov, Boris M.

1986-06-01

202

Simulating Complex Dynamics In Intermediate And Large-Aspect-Ratio Convection Systems  

Microsoft Academic Search

Buoyancy-induced (Rayleigh-Benard) convection of a fluid between two\\u000ahorizontal plates is a central paradigm for studying the transition to complex\\u000aspatiotemporal dynamics in sustained nonequilibrium systems. To improve the\\u000aanalysis of experimental data and the quantitative comparison of theory with\\u000aexperiment, we have developed a three-dimensional finite-difference code that\\u000acan integrate the three-dimensional Boussinesq equations (which govern the\\u000aevolution of

Ming-Chih Lai; Keng-Hwee Chiam; M. C. Cross; Henry Greenside

2000-01-01

203

Development of Polymer Gel Systems to Improve Volumetric Sweep and Reduce Producing Water/Oil Ratios  

SciTech Connect

Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of the third year of a 42 month research program that is aimed at an understanding of gelation chemistry and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work focused on a widely applied system in the field, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. Pre-gel aggregates form and grow as reactions between chromium acetate and polyacrylamide proceed. A mathematical model that describes uptake and crosslinking reactions as a function of time was derived. The model was probability based and provides molecular-weight averages and molecular-weight distributions of the pre-gel aggregates as a function of time and initial system conditions. A liquid chromatography apparatus to experimentally measure the size and molecular weight distributions of polymer samples was developed. The method worked well for polymer samples without the chromium crosslinker. Sample retention observed during measurements of gelant samples during the gelation process compromised the results. Other methods will be tested to measure size distributions of the pre-gel aggregates. Dissolution of carbonate minerals during the injection of gelants causes the pH of the gelant to increase. Chromium precipitates from solution at the higher pH values robbing the gelant of crosslinker. Experimental data on the transport of chromium acetate solutions through dolomite cores were obtained. A mathematical model that describes the transport of brine and chromium acetate solutions through rocks containing carbonate minerals was used to simulate the experimental results.

G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Feiyan Chen

2005-04-03

204

Mechanical Design of High Lift Systems for High Aspect Ratio Swept Wings  

NASA Technical Reports Server (NTRS)

The NASA Ames Research Center is working to develop a methodology for the optimization and design of the high lift system for future subsonic airliners with the involvement of two partners. Aerodynamic analysis methods for two dimensional and three dimensional wing performance with flaps and slats deployed are being developed through a grant with the aeronautical department of the University of California Davis, and a flap and slat mechanism design procedure is being developed through a contract with PKCR, Inc., of Seattle, WA. This report documents the work that has been completed in the contract with PKCR on mechanism design. Flap mechanism designs have been completed for seven (7) different mechanisms with a total of twelve (12) different layouts all for a common single slotted flap configuration. The seven mechanisms are as follows: Simple Hinge, Upside Down/Upright Four Bar Linkage (two layouts), Upside Down Four Bar Linkages (three versions), Airbus A330/340 Link/Track Mechanism, Airbus A320 Link/Track Mechanism (two layouts), Boeing Link/Track Mechanism (two layouts), and Boeing 767 Hinged Beam Four Bar Linkage. In addition, a single layout has been made to investigate the growth potential from a single slotted flap to a vane/main double slotted flap using the Boeing Link/Track Mechanism. All layouts show Fowler motion and gap progression of the flap from stowed to a fully deployed position, and evaluations based on spanwise continuity, fairing size and number, complexity, reliability and maintainability and weight as well as Fowler motion and gap progression are presented. For slat design, the options have been limited to mechanisms for a shallow leading edge slat. Three (3) different layouts are presented for maximum slat angles of 20 deg, 15 deg and 1O deg all mechanized with a rack and pinion drive similar to that on the Boeing 757 airplane. Based on the work of Ljungstroem in Sweden, this type of slat design appears to shift the lift curve so that higher lift is achieved with the deployed slat with no increase in angle of attack. The layouts demonstrate that these slat systems can be designed with no need for slave links, and an experimental test program is outlined to experimentally validate the lift characteristics of the shallow slat.

Rudolph, Peter K. C.

1998-01-01

205

A post-coding scheme for peak-to-average power ratio reduction in intensity modulated optical OFDM systems  

NASA Astrophysics Data System (ADS)

An efficient post-coding strategy is proposed in this letter to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals for optical intensity modulated direct detection (IM/DD) systems. The post-coding scheme based on discrete cosine transform (DCT) is employed after the inverse fast Fourier transform (IFFT) in the transmitter to reduce the PAPR of OFDM signals. This method is different from the conventional pre-coding scheme which is employed before IFFT operation. Numerical simulations demonstrate that the new DCT post-coding strategy can significantly reduce the PAPR than the conventional pre-coding scheme. Meantime, the bit error rate (BER) performance of the proposed post-coding system can be improved compared with the conventional pre-coding scheme.

Chen, Fang-ni; Wang, Zhong-peng

2014-07-01

206

Computer experiments on periodic systems identification using rotor blade transient flapping-torsion responses at high advance ratio  

NASA Technical Reports Server (NTRS)

Computer experiments are described which used transient responses in flap-bending and torsion of a rotor blade at high advance ratio. It was found that a simple system identification method applying a linear sequential estimator also called equation of motion estimator, is suitable for this periodic system and can be used directly, if only the acceleration data are noise-polluted. In the case where noise is also present in the state-variable data, the direct application of the estimator gave poor results. However after prefiltering the data with a digital Graham filter having a cutoff frequency above the natural blade torsion frequency, the linear sequential estimator successfully recovered the parameters of the periodic coefficient analytical model.

Hohenemser, K. H.; Prelewicz, D. A.

1974-01-01

207

Development of Polymer Gel Systems to Improve Volumetric Sweep and Reduce Producing Water/Oil Ratios  

SciTech Connect

Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of a 42-month research program that focused on the understanding of gelation chemistry and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work was conducted on a widely applied system in the field, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. Pre-gel aggregates form and grow as reactions between chromium acetate and polyacrylamide proceed. A rate equation that describes the reaction between chromium acetate and polymer molecules was regressed from experimental data. A mathematical model that describes the crosslinking reaction between two polymer molecules as a function of time was derived. The model was based on probability concepts and provides molecular-weight averages and molecular-weight distributions of the pre-gel aggregates as a function of time and initial system conditions. Average molecular weights of pre-gel aggregates were measured as a function of time and were comparable to model simulations. Experimental methods to determine molecular weight distributions of pre-gel aggregates were unsuccessful. Dissolution of carbonate minerals during the injection of gelants causes the pH of the gelant to increase. Chromium precipitates from solution at the higher pH values robbing the gelant of crosslinker. Experimental data on the transport of chromium acetate solutions through dolomite cores were obtained. A mathematical model that describes the transport of brine and chromium acetate solutions through rocks containing carbonate minerals was used to simulate the experimental results and data from literature. Gel treatments usually reduce the permeability to water to a greater extent than the permeability to oil is reduced. This phenomenon is referred to as disproportionate permeability reduction (DPR). Flow experiments were conducted in sandpacks to determine the effect of polymer and chromium concentrations on DPR. All gels studied reduced the permeability to water by a greater factor than the factor by which the oil permeability was reduced. Greater DPR was observed as the concentrations of polymer and chromium were increased. A conceptual model of the mechanisms responsible for DPR is presented. Primary features of the model are (1) the development of flow channels through the gel by dehydration and displacement of the gel and by re-connection of pre-treatment, residual oil volume and (2) high flow resistance in the channels during water flow is caused by significant saturations of oil remaining in the channels. A similar study of DPR was conducted in Berea sandstone cores. Both oil and water permeabilities were reduced by much smaller factors in Berea sandstone cores than in similar treatments in sandpacks. Poor maturation of the gelant in the Berea rock was thought to be caused by fluid-rock interactions that interfered with the gelation process.

G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Feiyan Chen

2005-12-31

208

DEVELOPMENT OF POLYMER GEL SYSTEMS TO IMPROVE VOLUMETRIC SWEEP AND REDUCE PRODUCING WATER/OIL RATIOS  

SciTech Connect

Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of the first year of a three-year research program that is aimed at the understanding of the chemistry of gelation and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work has focused on a widely-applied system in field applications, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. The initial reaction between chromium acetate and one polymer is referred to as the uptake reaction. The uptake reaction was studied as functions of chromium and polymer concentrations and pH values. Experimental data were regressed to determine a rate equation that describes the uptake reaction of chromium by polyacrylamide. Pre-gel aggregates form and grow as the reactions between chromium acetate and polyacrylamide proceed. A statistical model that describes the growth of pre-gel aggregates was developed using the theory of branching processes. The model gives molecular weight averages that are expressed as functions of the conversion of the reactive sites on chromium acetate or on the polymer molecule. Results of the application of the model correlate well with experimental data of viscosity and weight-average molecular weight and gives insights into the gelation process. A third study addresses the flow of water and oil in rock material after a gel treatment. Previous works have shown that gel treatments usually reduce the permeability to water to a greater extent than the permeability to oil is reduced. This phenomenon is referred to as disproportionate permeability reduction (DPR). Flow experiments were conducted to determine the effect of polymer and chromium concentrations on DPR. All gels studied reduced the permeability to water by a greater factor than the factor by which the oil permeability was reduced. Greater DPR was observed as the concentrations of polymer and chromium were increased. Increased pressure gradients during oil flow decreased the oil permeability and the water permeability that was measured afterward. Lower pressure gradients that were applied subsequently moderately affected water permeabilities but did not affect oil permeabilities. A conceptual model of the mechanisms responsible for DPR is presented. Primary features of the model are (1) the development of flow channels through the gel by dehydration of the gel and by re-connection of pre-treatment, residual oil volume and (2) high flow resistance in the channels during water flow is caused by significant saturations of oil remaining in the channels.

G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Rajeev Jain; Tuan Nguyen

2003-11-01

209

Signal-to-noise ratio estimation in digital computer simulation of lowpass and bandpass systems with applications to analog and digital communications, volume 3  

NASA Technical Reports Server (NTRS)

Techniques are developed to estimate power gain, delay, signal-to-noise ratio, and mean square error in digital computer simulations of lowpass and bandpass systems. The techniques are applied to analog and digital communications. The signal-to-noise ratio estimates are shown to be maximum likelihood estimates in additive white Gaussian noise. The methods are seen to be especially useful for digital communication systems where the mapping from the signal-to-noise ratio to the error probability can be obtained. Simulation results show the techniques developed to be accurate and quite versatile in evaluating the performance of many systems through digital computer simulation.

Tranter, W. H.; Turner, M. D.

1977-01-01

210

A short-standoff bistatic lidar system for aerosol cloud backscatter and fluorescence cross section, and depolarization ratio measurement  

NASA Astrophysics Data System (ADS)

We have designed a short-standoff bistatic lidar system, used for the direct measurement of the optical backscatter at 355-nm and 1064-nm and laser induced fluorescence (LIF) cross sections as well as depolarization ratio of aerosols inside a vacuum sealed, aerosol flow chamber. The 355- and 1064-nm beams are sent through the aerosol chamber at an angle of ~2° with respect to the field of view of the receiver optics to ensure that measurements reflect true backscatter. This bistatic lidar configuration naturally defines a limited region in space where the laser beams and the receiver field of view overlap, a region that can be easily quantified using a standard calibration procedure. Our technique also takes advantage of a specially designed vacuum sealed, aerosol flow chamber that provides a well-mixed, uniform aerosol distribution over the region of sensitivity. Both modeling results and experimental measurements confirm that little particle loss is observed inside the aerosol flow chamber. A TSI aerodynamic particle sizer (APS) is used to measure the aerosol concentration in the chamber, and the N2 concentration can be calculated using the measured temperature and pressure of the air inside the chamber. Optical backscatter and LIF cross sections are determined by comparing the measured elastic and LIF signals with the N2 Raman scattering signal from the same sample volume, a technique which eliminates the need for absolute radiometric calibration of the system. Instead, all detectors in the system are calibrated relative to the N2 Raman channel and the unknown aerosol cross sections are determined by taking the ratio of the backscatter (or LIF) signals to the Raman signal and multiplying by the well-known Raman cross section of N2. Particulate population depolarization parameters are determined by measuring the rejected polarized light from a Glan Laser prism polarizer and comparing those intensity measurements with that of the direct backscatter intensity. This work will focus on particle specific optical backscatter cross-sections and depolarization ratios for atmospherically relevant particle populations including Arizona road dust, black carbon, ammonium sulfate, and sodium chloride. Preliminary results of the absolute scattering cross-section and polarization parameters will be presented. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Glen, C.; Schmitt, R. L.; Sickafoose, S.; Johnson, M. S.; Shagam, R.; Reichardt, T.; Sanchez, A.; Servantes, B.

2012-12-01

211

An analysis of trading ratio for water pollution control trading systems using a geographic information system and the finite segment method  

NASA Astrophysics Data System (ADS)

Nitrogen from non-point sources reacts with the environment during flow to the waterway. These reactions cause decay of the pollutant. There is a question regarding whether pollution trades between point sources and non-point sources that involve nitrogen should consider this decay. The failure to consider this decay may cause trades to fail to achieve their environmental goal or to inefficiently achieve their environmental goal. Additionally, planners may consider the decay to target reductions and improve efficiency of trading programs. The dissertation uses a geographic information system (GIS) and the finite segment method to evaluate the need for the use of a trading ratio to consider decay. It uses GIS, principles of process engineering, and principles of hydrology to model the distribution of the nitrogen in the watershed with and without decay. Additionally, it compares the predictions of the concentrations with and without decay. Finally, it uses GIS to estimate appropriate values of trading ratio. The results show that the effect from decay during overland flow is appreciable but not always significant. The appropriate values of trading ratio are likely to be less than 1.3. Use of trading ratio may protect environmental quality and improve the efficiency of pollution control. However, sometimes the values of trading ratios are small relative to other factors so that the use of trading ratio is inconsequential. Finally, planners may use the decay of nitrogen from non-point sources to target the locations of the reductions to achieve the maximum decrease of concentration or to achieve the maximum increase of load without an increase in concentration.

Curley, Donald Edward

212

Plant lighting system with five wavelength-band light-emitting diodes providing photon flux density and mixing ratio control  

PubMed Central

Background Plant growth and development depend on the availability of light. Lighting systems therefore play crucial roles in plant studies. Recent advancements of light-emitting diode (LED) technologies provide abundant opportunities to study various plant light responses. The LED merits include solidity, longevity, small element volume, radiant flux controllability, and monochromaticity. To apply these merits in plant light response studies, a lighting system must provide precisely controlled light spectra that are useful for inducing various plant responses. Results We have developed a plant lighting system that irradiated a 0.18 m2 area with a highly uniform distribution of photon flux density (PFD). The average photosynthetic PFD (PPFD) in the irradiated area was 438 micro-mol m–2 s–1 (coefficient of variation 9.6%), which is appropriate for growing leafy vegetables. The irradiated light includes violet, blue, orange-red, red, and far-red wavelength bands created by LEDs of five types. The PFD and mixing ratio of the five wavelength-band lights are controllable using a computer and drive circuits. The phototropic response of oat coleoptiles was investigated to evaluate plant sensitivity to the light control quality of the lighting system. Oat coleoptiles irradiated for 23 h with a uniformly distributed spectral PFD (SPFD) of 1 micro-mol m–2 s–1 nm–1 at every peak wavelength (405, 460, 630, 660, and 735 nm) grew almost straight upwards. When they were irradiated with an SPFD gradient of blue light (460 nm peak wavelength), the coleoptiles showed a phototropic curvature in the direction of the greater SPFD of blue light. The greater SPFD gradient induced the greater curvature of coleoptiles. The relation between the phototropic curvature (deg) and the blue-light SPFD gradient (micro-mol m–2 s–1 nm–1 m–1) was 2 deg per 1 micro-mol m–2 s–1 nm–1 m–1. Conclusions The plant lighting system, with a computer with a graphical user interface program, can control the PFD and mixing ratios of five wavelength-band lights. A highly uniform PFD distribution was achieved, although an intentionally distorted PFD gradient was also created. Phototropic responses of oat coleoptiles to the blue light gradient demonstrated the merit of fine controllability of this plant lighting system. PMID:23173915

2012-01-01

213

Disentangling community functional components in a litter-macrodetritivore model system reveals the predominance of the mass ratio hypothesis  

PubMed Central

Recent investigations have shown that two components of community trait composition are important for key ecosystem processes: (i) the community-weighted mean trait value (CWM), related to the mass ratio hypothesis and dominant trait values in the community, and (ii) functional diversity (FD), related to the complementarity hypothesis and the divergence of trait values. However, no experiments controlling for the inherent dependence between CWM and FD have been conducted so far. We used a novel experimental framework to disentangle the unique and shared effects of CWM and FD in a leaf litter-macrodetritivore model system. We manipulated isopod assemblages varying in species number, CWM and FD of litter consumption rate to test the relative contribution of these community parameters in the decomposition process. We showed that CWM, but also the combination of CWM and FD, is a main factor controlling litter decomposition. When we tested individual biodiversity components separately, CWM of litter consumption rate showed a significant effect on decomposition, while FD and species richness alone did not. Our study demonstrated that (i) trait composition rather than species diversity drives litter decomposition, (ii) dominant trait values in the community (CWM) play a chief role in driving ecosystem processes, corroborating the mass ratio hypothesis, and (iii) trait dissimilarity can contribute in modulating the overall biodiversity effects. Future challenge is to assess whether the generality of our finding, that is, that dominant trait values (CWM) predominate over trait dissimilarity (FD), holds for other ecosystem processes, environmental conditions and different spatial and temporal scales. PMID:24634725

Bílá, Karolína; Moretti, Marco; Bello, Francesco; Dias, André TC; Pezzatti, Gianni B; Van Oosten, Arend Raoul; Berg, Matty P

2014-01-01

214

Design of a high voltage input - output ratio dc-dc converter dedicated to small power fuel cell systems  

NASA Astrophysics Data System (ADS)

Consuming chemical energy, fuel cells produce simultaneously heat, water and useful electrical power [J.M. Andújar, F. Segura, Renew. Sust. Energy Rev. 13, 2309 (2009)], [J. Larminie, A. Dicks, Fuel Cell Systems Explained, 2nd edn. (John Wiley & Sons, 2003)]. As a matter of fact, the voltage generated by a fuel cell strongly depends on both the load power demand and the operating conditions. Besides, as a result of many design aspects, fuel cells are low voltage and high current electric generators. On the contrary, electric loads are commonly designed for small voltage swing and a high V/I ratio in order to minimize Joule losses. Therefore, electric loads supplied by fuel cells are typically fed by means of an intermediate power voltage regulator. The specifications of such a power converter are to be able to step up the input voltage with a high ratio (a ratio of 10 is a classic situation) and also to work with an excellent efficiency (in order to minimize its size, its weight and its losses) [A. Shahin, B. Huang, J.P. Martin, S. Pierfederici, B. Davat, Energy Conv. Manag. 51, 56 (2010)]. This paper deals with the design of this essential ancillary device. It intends to bring out the best structure for fulfilling this function. Several dc-dc converters with large voltage step-up ratios are introduced. A topology based on a coupled inductor or tapped inductor is closely studied. A detailed modelling is performed with the purpose of providing designing rules. This model is validated with both simulation and implementation. The experimental prototype is based on the following specifications: the fuel cell output voltage ranges from a 50 V open-voltage to a 25 V rated voltage while the load requires a constant 250 V voltage. The studied coupled inductor converter is compared with a classic boost converter commonly used in this voltage elevating application. Even though the voltage regulator faces severe FC specifications, the measured efficiency reaches 96% at the rated power whereas conventional boost efficiency barely achieves 91.5% in the same operating conditions.

Béthoux, O.; Cathelin, J.

2010-12-01

215

Scaling of volume to surface ratio and doubling time in growing unicellular organisms: Do cells appear quantum-mechanical systems?  

NASA Astrophysics Data System (ADS)

The scaling of physical and biological characteristics of the living organisms is a basic method for searching of new biophysical laws. In series of previous studies the author showed that in Poikilotherms, Mammals and Aves, the volume to surface ratio V×S-1 (m) of organisms is proportional to their generation time Tgt(s) via growth rate v (m s-1): V×S-1 = vgr×Tr. The power and the correlation coefficients are near to 1.0. Aim of this study is: i) to prove with experimental data the validity of the above equation for Unicellular organisms and ii) to show that perhaps, the cells are quantum-mechanical systems. The data for body mass M (kg), density ? (kg/m3), minimum and maximum doubling time Tdt (s) for 50 unicellular organisms are assembled from scientific sources, and the computer program `Statistics' is used for calculations. In result i) the analytical relationship from type: V×S-1 = 4.46?10-11×Tdt was found, where vgr = 4.46×10-11 m/s and ii) it is shown that the products between cell mass M, cell length expressed by V/S ratio and growth rate vgr satisfied the Heisenberg uncertainty principle i.e. the inequalities V/S×M×vgr>h/2? and Tdt×M×vgr2>h/2? are valid, where h= 6.626×10-34 J?s is the Planck constant. This rise the question: do cells appear quantum-mechanical systems?

Atanasov, Atanas Todorov

2014-10-01

216

Scaling of volume to surface ratio and doubling time in growing unicellular organisms: Do cells appear quantum-mechanical systems?  

SciTech Connect

The scaling of physical and biological characteristics of the living organisms is a basic method for searching of new biophysical laws. In series of previous studies the author showed that in Poikilotherms, Mammals and Aves, the volume to surface ratio V×S{sup ?1} (m) of organisms is proportional to their generation time T{sub gt}(s) via growth rate v (m s{sup ?1}): V×S{sup ?1}?=?v{sub gr}×T{sup r}. The power and the correlation coefficients are near to 1.0. Aim of this study is: i) to prove with experimental data the validity of the above equation for Unicellular organisms and ii) to show that perhaps, the cells are quantum-mechanical systems. The data for body mass M (kg), density ? (kg/m{sup 3}), minimum and maximum doubling time T{sub dt} (s) for 50 unicellular organisms are assembled from scientific sources, and the computer program ‘Statistics’ is used for calculations. In result i) the analytical relationship from type: V×S{sup ?1}?=?4.46?10{sup ?11}×T{sub dt} was found, where v{sub gr}?=?4.46×10{sup ?11} m/s and ii) it is shown that the products between cell mass M, cell length expressed by V/S ratio and growth rate v{sub gr} satisfied the Heisenberg uncertainty principle i.e. the inequalities V/S×M×v{sub gr}>h/2? and T{sub dt}×M×v{sub gr}{sup 2}>h/2? are valid, where h= 6.626×10{sup ?34} J?s is the Planck constant. This rise the question: do cells appear quantum-mechanical systems?.

Atanasov, Atanas Todorov, E-mail: atanastod@abv.bg [Department of Physics and Biophysics, Faculty of Medicine, Trakia University, 11 Armeiska Str., 6000 Stara Zagora (Bulgaria)

2014-10-06

217

Radius Ratio  

NSDL National Science Digital Library

This is a set of animations that demonstrates properties of the spherical holes formed when uniform spheres are packed. Cubic, octahedral and tetrahedral packing arrangements may be examined without anything in the holes,and with the repective holes filled. The sizes of the various holes relative to the spheres being packed are shown, which can lead students into an exploration of the radius ratio concept. An example is given of computing the relative size of an octahedral hole.

218

Behavior of aircraft antiskid breaking systems on dry and wet runway surfaces: A slip-ratio-controlled system with ground speed reference from unbraked nose wheel  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted at the Langley aircraft landing loads and traction facility to study the braking and cornering response of a slip ratio controlled aircraft antiskid braking system with ground speed reference derived from an unbraked nose wheel. The investigation, conducted on dry and wet runway surfaces, utilized one main gear wheel, brake, and tire assembly of a DC-9 series 10 airplane. During maximum braking, the average ratio of the drag force friction coefficient developed by the antiskid system to the maximum drag force friction coefficient available was higher on the dry surface than on damp and flooded surfaces, and was reduced with lighter vertical loads, higher yaw angles, and when new tire treads were replaced by worn treads. Similarly, the average ratio of side force friction coefficient developed by the tire under antiskid control to the maximum side force friction coefficient available to a freely rolling yawed tire decreased with increasing yaw angle, generally increased with ground speed, and decreased when tires with new treads were replaced by those with worn treads.

Tanner, J. A.; Stubbs, S. M.

1977-01-01

219

A Tropical Lake Breeze System : The Effect on Surface NO, NO2, O3, and CO2 Mixing Ratios  

NASA Astrophysics Data System (ADS)

During the Cooperative LBA Airborne Regional Experiment 2001 (CLAIRE2001, July 2001), we investigated diel variations of nitric oxide (NO), nitrogen dioxide (NO_2), ozone (O_3) and carbon dioxide (CO_2) mixing ratios at Balbina Limnological Station (01^o55'994''S, 59^o28'071''W, Amazonia,Brazil). We applied sensitive and species-specific chemiluminescence (NO, NO_2, O_3) and NDIR (CO_2) analysers to record ambient mixing ratios on 1 min intervals. Simultaneously, we extensively monitored (micro-)meteorological qauntities (air temperature, relative humidity, wind speed and -direction, thermal stratification, rainfall intensity, soil temperatures and moisture, as well as radiation fluxes (global, net, short wave, NO_2 photolysis, and photosynthetic active)). Balbina Limnological Station is located just a few hundred meters south of a 2.360 km^2 hydroelectric power dam (Usina Hidrelétrica de Balbina) and about 100m north from the edge of a primary rainforest. Marked differences in surface albedo and heat storage capacity generate a local wind system, the lake breeze, which advects air from the dam (09:00 to 15:00 local) and from the rainforest (18:00 to 06:00 local), respectively. Generally, we observed marked diel variations of NO, NO_2, O_3, and CO_2 (high/low levels during night/day) and O_3 (low/high levels during night/day). Especially in the tropics, this behaviour is usually related to (a) accumulation of soil emissions (NO, CO_2), chemical reactions (NO, from NO_2-O_3 reaction) and surface destruction (O_3) in a shallow and strong nocturnal boundary layer inversion, and (b) to soil emission (NO), photochemical reactions (NO-NO_2-O_3), dry deposition/plant uptake (NO_2, O_3, and CO_2) and strong turbulent vertical mixing in the daytime mixed layer. However, under the specific conditions of the lake breeze soil emission and dry deposition/ plant uptake can be neglected during daytime. Consequently, the investigation of daytime mixing ratios can be confined to the influence of photochemical reactions (photo-stationarity) and boundary layer mixing.

Lima Moura, M. A.; Eça D'Almeida Rocha, C. H.; Trebs, I.; Andreae, M. O.; Meixner, F. X.

2003-04-01

220

Performance of the wet oxidation unit of the HPLC isotope ratio mass spectrometry system for halogenated compounds.  

PubMed

The performance of liquid chromatography-isotope ratio mass spectrometry (LC-IRMS) for polar halogenated compounds was evaluated. Oxidation capacity of the system was tested with halogenated acetic acids and halogenated aromatic compounds. Acetic acid (AA) was selected as a reference compound for complete oxidation and compared on the molar basis to the oxidation of other analytes. The isotope values were proofed with calibrated ?(13)C values obtained with an elemental analyzer (EA). Correct isotope values were obtained for mono- and dichlorinated, fluorinated, and tribrominated acetic acids and also for aniline, phenol, benzene, bromobenzene, chlorobenzene, 1,2-dichlorobenzene, 2,4,6-trichlorophenol, pentafluorophenol, and nitrobenzene. Incomplete oxidation of trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) resulted in lower recovery compared to AA (37% and 24%, respectively) and in isotopic shift compared to values obtained with EA (TCA ??(13)C(EA/LC-IRMS) = 8.8‰, TFA ??(13)C(EA/LC-IRMS) = 6.0‰). Improvement of oxidation by longer reaction time in the reactor and increase in the concentration of sulfate radicals did not lead to complete combustion of TCA and TFA needed for ?(13)C analysis. To the best of our knowledge, this is the first time such highly chlorinated compounds were studied with the LC-IRMS system. This work provides information for method development of LC-IRMS methods for halogenated contaminants that are known as potential threats to public health and the environment. PMID:24975492

Gilevska, Tetyana; Gehre, Matthias; Richnow, Hans Hermann

2014-08-01

221

The ALFALFA "Almost Darks" Campaign: Pilot VLA HI Observations of Five High Mass-to-Light Ratio Systems  

E-print Network

We present VLA HI spectral line imaging of 5 sources discovered by ALFALFA. These targets are drawn from a larger sample of systems that were not uniquely identified with optical counterparts during ALFALFA processing, and as such have unusually high HI mass to light ratios. These candidate "Almost Dark" objects fall into 4 categories: 1) objects with nearby HI neighbors that are likely of tidal origin; 2) objects that appear to be part of a system of multiple HI sources, but which may not be tidal in origin; 3) objects isolated from nearby ALFALFA HI detections, but located near a gas-poor early-type galaxy; 4) apparently isolated sources, with no object of coincident redshift within ~400 kpc. Roughly 75% of the 200 objects without identified counterparts in the $\\alpha$.40 database (Haynes et al. 2011) fall into category 1. This pilot sample contains the first five sources observed as part of a larger effort to characterize HI sources with no readily identifiable optical counterpart at single dish resolutio...

Cannon, John M; Leisman, Lukas; Haynes, Martha P; Adams, Elizabeth A K; Giovanelli, Riccardo; Hallenbeck, Gregory; Janowiecki, Steven; Jones, Michael; Józsa, Gyula I G; Koopmann, Rebecca A; Nichols, Nathan; Papastergis, Emmanouil; Rhode, Katherine L; Salzer, John J; Troischt, Parker

2014-01-01

222

Influence of Cooling to Heating Load Ratio on Optimal Supply Water and Air Temperatures in an Air Conditioning System  

NASA Astrophysics Data System (ADS)

In planning an air conditioning system, supply water and air temperatures are important factors from the viewpoint of energy saving and cost reduction. For example, lower temperature supply water and air for space cooling reduce the coefficient of performance of a refrigeration machine, and increase the thickness of heat insulation material. However, they enable larger temperature differences, and reduce equipment sizes and power demand. It is also an important subject to evaluate the effect of the supply water and air temperatures on energy saving and cost reduction on the annual basis by considering not only cooling but also heating loads. The purposes of this paper are to propose an optimal planning method for an air conditioning system with large temperature difference, and to analyze the effect of supply water and air temperatures on the long-term economics through a numerical study for an office building. As a result, it is shown that the proposed method effectively determines supply water and air temperatures, and the influence of the cooling to heating load ratio on the long-term economics is clarified.

Karino, Naoki; Shiba, Takashi; Yokoyama, Ryohei; Ito, Koichi

223

The Alfalfa “Almost Darks” Campaign: Pilot VLA HI Observations of Five High Mass-To-Light Ratio Systems  

NASA Astrophysics Data System (ADS)

We present new Very Large Array (VLA) H i spectral line imaging of five sources discovered by the ALFALFA extragalactic survey. These targets are drawn from a larger sample of systems that were not uniquely identified with optical counterparts during ALFALFA processing, and as such have unusually high H i mass to light ratios. The candidate “Almost Dark” objects fall into four broad categories: (1) objects with nearby H i neighbors that are likely of tidal origin; (2) objects that appear to be part of a system of multiple H i sources, but which may not be tidal in origin; (3) objects isolated from nearby ALFALFA H i detections, but located near a gas-poor early type galaxy; (4) apparently isolated sources, with no object of coincident redshift within ˜400 kpc. Roughly 75% of the 200 objects without identified counterparts in the ?.40 database (Haynes et al. 2011) fall into category 1 (likely tidal), and were not considered for synthesis follow-up observations. The pilot sample presented here (AGC193953, AGC208602, AGC208399, AGC226178, and AGC233638) contains the first five sources observed as part of a larger effort to characterize H i sources with no readily identifiable optical counterpart at single dish resolution (3.?5). These objects span a range of H i mass [7.41 < log(MHi ) < 9.51] and H i mass to B-band luminosity ratios (3 < MHi /LB < 9). We compare the H i total intensity and velocity fields to optical imaging drawn from the Sloan Digital Sky Survey and to ultraviolet imaging drawn from archival GALEX observations. Four of the sources with uncertain or no optical counterpart in the ALFALFA data are identified with low surface brightness optical counterparts in Sloan Digital Sky Survey imaging when compared with VLA H i intensity maps, and appear to be galaxies with clear signs of ordered rotation in the H i velocity fields. Three of these are detected in far-ultraviolet GALEX images, a likely indication of star formation within the last few hundred Myrs. One source (AGC208602) is likely tidal in nature, associated with the NGC 3370 group. Consistent with previous efforts, we find no “dark galaxies” in this limited sample. However, the present observations do reveal complex sources with suppressed star formation, highlighting both the observational difficulties and the necessity of synthesis follow-up observations to understand these extreme objects.

Cannon, John M.; Martinkus, Charlotte P.; Leisman, Lukas; Haynes, Martha P.; Adams, Elizabeth A. K.; Giovanelli, Riccardo; Hallenbeck, Gregory; Janowiecki, Steven; Jones, Michael; Józsa, Gyula I. G.; Koopmann, Rebecca A.; Nichols, Nathan; Papastergis, Emmanouil; Rhode, Katherine L.; Salzer, John J.; Troischt, Parker

2015-02-01

224

The influence and optimization design of transmission ratio on the performances of gimbal Servo-system in CMG  

Microsoft Academic Search

The transmission ratio of the transmission mechanism will affect its efficiency, mass and size, and the performances of gimbal motor in control moment gyro (CMG) for stabilization of spacecraft attitude. In this paper, the transmission ratio of transmission mechanism is optimized for achieving the minimum of the peak output torque of gimbal motor minimum. The relationship curve between the peak

Bang-cheng Han; Ji-jun Ma

2010-01-01

225

Quenching Effect, Signal to Noise, Contrast to Noise Ratios on Scintillator Screens for Proton Beam Dosimetry System  

NASA Astrophysics Data System (ADS)

There has been dosimetry using scintillator screen for proton quality assurance recently. To develop a proton beam dosimetry system using scintillator, we evaluated the dosimetric properties and imaging quality for three kinds of scintillator screens. Proton beam ranges of 6, 9, and 12 g/cm2 were determined in a water phantom using an ion chamber. Beam current was optimized about each scintillator screen at proton beam ranges of 6, 9, and 12 g/cm2. Dose rate was in beam condition of proton treatment. For comparison of the dosimetric properties, the quenching correction factors and standard deviations for the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) were obtained using the relation between the light yield (scintillator-relative output) and the dose distribution (diode-relative output). The image qualities for the scintillator screens were compared, using the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR), in consideration of the physical properties of the scintillator materials. After correction of the quenching effect, the correction factor for scintillator screen Gd2O2S:Tb was the lowest, at 0.004 g/(cm2 MeV). The standard deviations of the difference between the yields measured by the scintillator screens and the diode detector averaged 1, 1.3, and 1.3, respectively, at all of the ranges from origin to the peak position. The dosimetric properties of scintillator screens were no large difference. The SNRs of the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) averaged 28.67, 40.18, and 24.56, respectively, at all ranges. The CNRs of the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) averaged 0.44, 0.33, and 0.42, respectively, at all ranges. The highest SNR and the lowest CNR of scintillator screen Gd2O2S:Tb were more excellent than those of the other scintillator screens. We evaluated the dosimetric properties in terms of the quenching-effect correction factors, standard deviations image qualities in terms of SNR and CNR about scintillator screens. The correction factor and standard deviation for scintillator screens made no large difference. Scintillator screen Gd2O2S:Tb had the highest value of SNR and the lowest value of CNR, and accordingly was considered to be best in proton beam imaging quality.

Kim, Seonkyu; Byeong Lee, Se; Yoo, Seung Hoon; Cho, Sungkoo; Kim, Dong Wook; Shin, Dongho; Park, Sung Yong; Kim, Chan Hyeong; Lee, Sang Hoon

2012-04-01

226

Fuel Cycle System Analysis Implications of Sodium-Cooled Metal-Fueled Fast Reactor Transuranic Conversion Ratio  

SciTech Connect

If advanced fuel cycles are to include a large number of fast reactors (FRs), what should be the transuranic (TRU) conversion ratio (CR)? The nuclear energy era started with the assumption that they should be breeder reactors (CR > 1), but the full range of possible CRs eventually received attention. For example, during the recent U.S. Global Nuclear Energy Partnership program, the proposal was burner reactors (CR < 1). Yet, more recently, Massachusetts Institute of Technology's "Future of the Nuclear Fuel Cycle" proposed CR [approximately] 1. Meanwhile, the French company EDF remains focused on breeders. At least one of the reasons for the differences of approach is different fuel cycle objectives. To clarify matters, this paper analyzes the impact of TRU CR on many parameters relevant to fuel cycle systems and therefore spans a broad range of topic areas. The analyses are based on a FR physics parameter scan of TRU CR from 0 to [approximately]1.8 in a sodium-cooled metal-fueled FR (SMFR), in which the fuel from uranium-oxide-fueled light water reactors (LWRs) is recycled directly to FRs and FRs displace LWRs in the fleet. In this instance, the FRs are sodium cooled and metal fueled. Generally, it is assumed that all TRU elements are recycled, which maximizes uranium ore utilization for a given TRU CR and waste radiotoxicity reduction and is consistent with the assumption of used metal fuel separated by electrochemical means. In these analyses, the fuel burnup was constrained by imposing a neutron fluence limit to fuel cladding to the same constant value. This paper first presents static, time-independent measures of performance for the LWR [right arrow] FR fuel cycle, including mass, heat, gamma emission, radiotoxicity, and the two figures of merit for materials for weapon attractiveness developed by C. Bathke et al. No new fuel cycle will achieve a static equilibrium in the foreseeable future. Therefore, additional analyses are shown with dynamic, time-dependent measures of performance including uranium usage, TRU inventory, and radiotoxicity to evaluate the complex impacts of transition from the current uranium-fueled LWR system, and other more realistic impacts that may not be intuited from the time-independent steady-state conditions of the end-state fuel cycle. These analyses were performed using the Verifiable Fuel Cycle Simulation Model VISION. Compared with static calculations, dynamic results paint a different picture of option space and the urgency of starting a FR fleet. For example, in a static analysis, there is a sharp increase in uranium utilization as CR exceeds 1.0 (burner versus breeder). However, in dynamic analyses that examine uranium use over the next 1 to 2 centuries, behavior as CR crosses the 1.0 threshold is smooth, and other parameters such as the time required outside of reactors to recycle fuel become important. Overall, we find that there is no unambiguously superior value of TRU CR; preferences depend on the relative importance of different fuel cycle system objectives.

Steven J. Piet; Edward A. Hoffman; Samuel E. Bays; Gretchen E. Matthern; Jacob J. Jacobson; Ryan Clement; David W. Gerts

2013-03-01

227

ENRICHMENT OF THE DUST-TO-GAS MASS RATIO IN BONDI/JEANS ACCRETION/CLOUD SYSTEMS DUE TO UNEQUAL CHANGES IN DUST AND GAS INCOMING VELOCITIES  

E-print Network

ENRICHMENT OF THE DUST-TO-GAS MASS RATIO IN BONDI/JEANS ACCRETION/CLOUD SYSTEMS DUE TO UNEQUAL CHANGES IN DUST AND GAS INCOMING VELOCITIES P. M. Bellan Applied Physics, California Institute. It is shown that high-velocity dust impinging on this cloud will tend to pile up due to having a different

Bellan, Paul M.

228

Rule-based fuzzy inference system for estimating the influent COD/N ratio and ammonia load to a sequencing batch reactor.  

PubMed

A fuzzy inference system using sensor measurements was developed to estimate the influent COD/N ratio and ammonia load. The sensors measured ORP, DO and pH. The sensor profiles had a close relationship with the influent COD/N ratio and ammonia load. To confirm this operational knowledge for constructing a rule set, a correlation analysis was conducted. The results showed that a rule generation method based only on operational knowledge did not generate a sufficiently accurate relationship between sensor measurements and target variables. To compensate for this defect, a decision tree algorithm was used as a standardized method for rule generation. Given a set of inputs, this algorithm was used to determine the output variables. However, the generated rules could not estimate the continuous influent COD/N ratio and ammonia load. Fuzzified rules and the fuzzy inference system were developed to overcome this problem. The fuzzy inference system estimated the influent COD/N ratio and ammonia load quite well. When these results were compared to the results from a predictive polynomial neural network model, the fuzzy inference system was more stable. PMID:16532750

Kim, Y J; Bae, H; Ko, J H; Poo, K M; Kim, S; Kim, C W; Woo, H J

2006-01-01

229

Impact of total organic carbon and chlorine to ammonia ratio on nitrification in a bench-scale drinking water distribution system  

Microsoft Academic Search

Nitrification occurs in chloraminated drinking water systems and is affected by water quality parameters. The aim of this\\u000a study was to investigate the impact of total organic carbon and chlorine to ammonia ratio on nitrification potential in a\\u000a simulated drinking water distribution system as during chloramination. The occurrence of nitrification and activity of nitrifying\\u000a bacteria was primarily monitored using four

Yongji Zhang; Lingling Zhou; Guo Zeng; Huiping Deng; Guibai Li

2010-01-01

230

A High-precision Measurement System for Carbon and Hydrogen Isotopic Ratios of Atmospheric Methane and Its Application to Air Samples Collected in the Western Pacific Region  

Microsoft Academic Search

In order to study temporal and spatial variations of atmospheric CH4 quantitatively, we originally improved a measurement system for carbon and hydrogen isotopic ratios (?13C and ?D) of CH4 to attain high-precision measurements. By analyzing 100 mL aliquots of an ambient air sample, the precision of our system is 0.080‰ for ?13C and 2.20‰ for ?D(1?), which are one of

Taku UMEZAWA; Shuji AOKI; Takakiyo NAKAZAWA; Shinji MORIMOTO

2009-01-01

231

Measurements of concentrations of chlorofluoromethanes (CFMs) carbon dioxide and carbon isotope ratio in stratospheric and tropospheric air by grab-sampling systems  

Microsoft Academic Search

Measurements of concentrations of chlorofluoromethanes (CFMs), carbon dioxide and carbon isotope ratio in stratospheric and tropospheric air by grab-sampling systems are reported. The balloon-borne grab-sampling system has been launched from Sanriku Balloon Center three times since 1981. It consists of: (1) six sampling cylinders, (2) eight motor driven values, (3) control and monitor circuits, and (4) pressurized housing. Particular consideration

T. Itoh; H. Kubo; H. Honda; T. Tominaga; Y. Makide; A. Yakohata; H. Sakai

1985-01-01

232

Measurements of concentrations of chlorofluoromethanes (CFMs) carbon dioxide and carbon isotope ratio in stratospheric and tropospheric air by grab-sampling systems  

NASA Technical Reports Server (NTRS)

Measurements of concentrations of chlorofluoromethanes (CFMs), carbon dioxide and carbon isotope ratio in stratospheric and tropospheric air by grab-sampling systems are reported. The balloon-borne grab-sampling system has been launched from Sanriku Balloon Center three times since 1981. It consists of: (1) six sampling cylinders, (2) eight motor driven values, (3) control and monitor circuits, and (4) pressurized housing. Particular consideration is paid to the problem of contamination. Strict requirements are placed on the choice of materials and components, construction methods, cleaning techniques, vacuum integrity, and sampling procedures. An aluminum pressurized housing and a 4-m long inlet line are employed to prevent the sampling air from contamination by outgassing of sampling and control devices. The sampling is performed during the descent of the system. Vertical profiles of mixing ratios of CF2Cl2, CFCl3 and CH4 are given. Mixing ratios of CF2Cl2 and CFCl3 in the stratosphere do not show the discernible effect of the increase of those in the ground level background, and decrease with altitude. Decreasing rate of CFCl3 is larger than that of CF2Cl2. CH4 mixing ratio, on the other hand, shows diffusive equilibrium, as the photodissociation cross section of CH4 is small and concentrations of OH radical and 0(sup I D) are low.

Itoh, T.; Kubo, H.; Honda, H.; Tominaga, T.; Makide, Y.; Yakohata, A.; Sakai, H.

1985-01-01

233

On the security evaluation of a multibiometric system based on a voting strategy involving likelihood ratio statistic tests  

Microsoft Academic Search

Multimodal biometric systems integrate information from multiple sources to improve the performance of a typical unimodal biometric system. The use of multimodal biometric systems has been encouraged by the threat of spoofing, where an impostor fakes a biometric trait. The reason lies on the assumption that, an impostor must fake all the fused modalities to be accepted. Recent studies showed

Emanuela Marasco; Carlo Sansone

2011-01-01

234

Data generation for shear modulus and damping ratio in reinforced sands using adaptive neuro-fuzzy inference system  

Microsoft Academic Search

Neuro-fuzzy inference systems have been used in many areas in civil engineering applications. This study was conducted to estimate low strain dynamic properties of composite media from easily measurable physical properties using the adaptive neuro-fuzzy inference system (ANFIS). The inference system was employed to predict the shear modulus and the damping coefficient of the sand samples as an alternative to

Suat Akbulut; A. Samet Hasiloglu; Sibel Pamukcu

2004-01-01

235

Tests of variable-band multilayers designed for investigating optimal signal-to-noise vs artifact signal ratios in Dual-Energy Digital Subtraction Angiography (DDSA) imaging systems  

SciTech Connect

In recent work, various design techniques were applied to investigate the feasibility of controlling the bandwidth and bandshape profiles of tungsten/boron-carbon (W/B{sub 4}C) and tungsten/silicon (W/Si) multilayers for optimizing their performance in synchrotron radiation based angiographical imaging systems at 33 keV. Varied parameters included alternative spacing geometries, material thickness ratios, and numbers of layer pairs. Planar optics with nominal design reflectivities of 30%--94% and bandwidths ranging from 0.6%--10% were designed at the Stanford Radiation Laboratory, fabricated by the Ovonic Synthetic Materials Company, and characterized on Beam Line 4-3 at the Stanford Synchrotron Radiation Laboratory, in this paper we report selected results of these tests and review the possible use of the multilayers for determining optimal signal to noise vs. artifact signal ratios in practical Dual-Energy Digital Subtraction Angiography systems.

Boyers, D.; Ho, A.; Li, Q.; Piestrup, M. [Adelphi Technology, Inc., Palo Alto, CA (United States); Rice, M.; Tatchyn, R. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

1993-08-01

236

System and method to estimate compressional to shear velocity (VP/VS) ratio in a region remote from a borehole  

SciTech Connect

In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed. In some aspects, the method includes arranging a first source in the borehole and generating a steered beam of elastic energy at a first frequency; arranging a second source in the borehole and generating a steerable beam of elastic energy at a second frequency, such that the steerable beam at the first frequency and the steerable beam at the second frequency intercept at a location away from the borehole; receiving at the borehole by a sensor a third elastic wave, created by a three wave mixing process, with a frequency equal to a difference between the first and second frequencies and a direction of propagation towards the borehole; determining a location of a three wave mixing region based on the arrangement of the first and second sources and on properties of the third wave signal; and creating three-dimensional images of the non-linear properties using data recorded by repeating the generating, receiving and determining at a plurality of azimuths, inclinations and longitudinal locations within the borehole. The method is additionally used to generate three dimensional images of the ratio of compressional to shear acoustic velocity of the same volume surrounding the borehole.

Vu, Cung; Nihei, Kurt T; Schmitt, Denis P; Skelt, Christopher; Johnson, Paul A; Guyer, Robert; TenCate, James A; Le Bas, Pierre-Yves

2012-10-16

237

Band Mechanism with Nonlinear Gear Ratio for Gravity Force Balance: Design and Analysis in Total System Network  

NASA Astrophysics Data System (ADS)

The application of band mechanisms offers a wide range of possibilities in designing concepts of modern guide mechanisms. The applied belt pulleys are designed as continuous convex cam disks and allow the application of different transmission functions. A large number of transmission functions can be generated with convex curve shapes. It takes a great deal of effort to determine the correct pulley curve and is difficult for engineers without special knowledge to calculate. The syntheses process of a nonlinear band mechanism is based on the relationships between the evolute and evolvente [1]. The evolute corresponds to the pulley curve and the evolvente corresponds, for example, to the curve of the fix point of a rocker arm. By applying this method in relation with the reverse kinematics and the maintenance of total band length, allowing to generate band mechanism with required curve of transmission ratio. Beside the comments of band mechanism construction and the mathematical method of resolution—the first part of the article explains a simple four bar mechanism of couch chest the total gravity force balance with band mechanism. Therefore, the essential computing steps and limits of the solving process will be explained. With this it is possible to calculate the nonlinear transmission ratio of band mechanism with consideration of elastic band properties and inertia of bodies.

Ebert, F.; Berger, M.

238

Design verification and fabrication of active control systems for the DAST ARW-2 high aspect ratio wing, part 1  

NASA Technical Reports Server (NTRS)

A study was conducted under Drones for Aerodynamic and Structural Testing (DAST) program to accomplish the final design and hardware fabrication for four active control systems compatible with and ready for installation in the NASA Aeroelastic Research Wing No. 2 (ARW-2) and Firebee II drone flight test vehicle. The wing structure was designed so that Active Control Systems (ACS) are required in the normal flight envelope by integrating control system design with aerodynamics and structure technologies. The DAST ARW-2 configuration uses flutter suppression, relaxed static stability, and gust and maneuver load alleviation ACS systems, and an automatic flight control system. Performance goals and criteria were applied to individual systems and the systems collectively to assure that vehicle stability margins, flutter margins, flying qualities and load reductions are achieved.

Mcgehee, C. R.

1986-01-01

239

Effect of side-mode suppression ratio on the performance of self-seeded gain-switched optical pulses in lightwave communications systems  

Microsoft Academic Search

The side-mode suppression ratio (SMSR) of self-seeded gain-switched optical pulses is shown to be an extremely important factor for the use of these pulses in optical communications systems. Experiments carried out involving pulse propagation through dispersion-shifted fiber and a bandpass optical filter demonstrate that, for SMSR values of less than 25 dB, the buildup of noise due to the mode

L. P. Barry; P. Anandarajah

1999-01-01

240

Self-organizes fuzzy neural network and its application to build modeling of the ratio of fuel to water control system in the ultra supercritical unit  

Microsoft Academic Search

For ultra supercritical unit concurrent boiler with characteristics of parameters distribution, nonlinear and coupling tightly multivariable, this paper proposed a method based on self-organizes fuzzy neural network to build model for the ratio of fuel to water control system. The self-organizes fuzzy neural network with better non-linear approximation ability, good user-friendly, better forecast precision and generalization ability and other advantages,

Jia Qing-yan; Pan Yang; Liu Lin; Wang Peng; Hu Wen-dong

2011-01-01

241

Denitrification and nitrous oxide to nitrous oxide plus dinitrogen ratios in the soil profile under three tillage systems  

Microsoft Academic Search

There is a growing interest in the adoption of conservation tillage systems [no-till (NT) and reduced tillage (RT)] as alternatives to conventional tillage (CT) systems. A 2-year study was conducted to investigate possible environmental consequences of three tillage systems on a 2.4-ha field located at Macdonald Research Farm, McGill University, Montreal. The soil was a sandy loam (0.5 m depth) underlain

Abdirashid A. Elmi; Chandra Madramootoo; Chantal Hamel; Aiguo Liu

2003-01-01

242

A simple peak-to-average power ratio reduction scheme for all optical orthogonal frequency division multiplexing systems with intensity modulation and direct detection.  

PubMed

This paper fundamentally investigates the peak-to-average power ratio (PAPR) theory in all optical orthogonal frequency division multiplexing (OFDM) systems which employ intensity modulation-direct detection (IM-DD) scheme. We propose a low-complexity PAPR reduction scheme based on phase pre-emphasis. Simulations show that the proposed scheme brings about a 3.74 dB PAPR reduction and better nonlinear impairment tolerance in a 16x10Gb/s IM-DD all optical OFDM system. PMID:19724560

Liang, Xiaojun; Li, Wei; Ma, Weidong; Wang, Kai

2009-08-31

243

Isotopic ratio, isotonic ratio, isobaric ratio and Shannon information uncertainty  

E-print Network

The isoscaling and the isobaric yield ratio difference (IBD) probes, which both are constructed by yield ratio of fragment, provide cancelation of parameters. The information entropy theory is introduced to explain the physical meaning of the isoscaling and IBD probes. The similarity between the isoscaling and IBD results is found, i.e., the information uncertainty determined by the IBD method equals to $\\beta-\\alpha$ determined by the isoscaling [$\\alpha$ ($\\beta$) is the parameter fitted from the isotopic (isotonic) yield ratio].

Chun-Wang Ma; Hui-Ling Wei

2014-09-11

244

Isotopic Ratio, Isotonic Ratio, Isobaric Ratio and Shannon Information Uncertainty  

NASA Astrophysics Data System (ADS)

The isoscaling and the isobaric yield ratio difference (IBD) probes, both of which are constructed by yield ratio of fragment, provide cancelation of parameters. The information entropy theory is introduced to explain the physical meaning of the isoscaling and IBD probes. The similarity between the isoscaling and IBD results is found, i.e., the information uncertainty determined by the IBD method equals to ? – ? determined by the isoscaling (? (?) is the parameter fitted from the isotopic (isotonic) yield ratio).

Ma, Chun-Wang; Wei, Hui-Ling

2014-11-01

245

Ratios, Proportions, Similarity  

NSDL National Science Digital Library

This is a set of four, one-page problems about the size of planets compared to earth. Learners may use ratios to compare planets within our solar system or those outside of our solar system with the earth. Options are presented so that students may learn about the MESSENGER mission to Mercury through a NASA press release or by viewing a NASA eClips video [6 min.]. This activity is part of the Space Math multi-media modules that integrate NASA press releases, NASA archival video, and mathematics problems targeted at specific math standards commonly encountered in middle school.

246

Carrier power to intermodulation-distortion power-ratio-increasing technique in active phased-array antenna systems  

Microsoft Academic Search

This paper describes a novel technique to compensate for the intermodulation (IM) distortion components of high-power amplifiers in an active phased-array antenna system. This technique uses IM phase control to break the strong association between carriers and IM components, and can make the radiation patterns of carriers and IM components different on active phased-array antenna systems. As a result, carrier

Takana Kaho; Tadao Nakagawa; Katsuhiko Araki; Kohji Horikawa

2002-01-01

247

Biodegradable in situ gelling delivery systems containing pilocarpine as new antiglaucoma formulations: effect of a mercaptoacetic acid/N-isopropylacrylamide molar ratio  

PubMed Central

Ocular drug delivery is one of the most commonly used treatment modalities in the management of glaucoma. We have recently proposed the use of gelatin and poly(N-isopropylacrylamide) (PNIPAAm) graft copolymers as biodegradable in situ forming delivery systems for the intracameral administration of antiglaucoma medications. In this study, we further investigated the influence of carrier characteristics on drug delivery performance. The carboxyl-terminated PNIPAAm samples with different molecular weights were synthesized by varying the molar ratio of mercaptoacetic acid (MAA)/N-isopropylacrylamide (NIPAAm) from 0.05 to 1.25, and were determined by end-group titration. The preparation of gelatin-g-PNIPAAm (GN) copolymers from these thermoresponsive polymers was achieved using carbodiimide chemistry. Our results showed that the carboxylic end-capped PNIPAAm of high molecular weight may lead to the lower thermal phase transition temperature and slower degradation rate of GN vehicles than its low molecular weight counterparts. With a decreasing MAA/NIPAAm molar ratio, the drug encapsulation efficiency of copolymers was increased due to fast temperature-triggered capture of pilocarpine nitrate. The degradation of the gelatin network could greatly affect the drug release profiles. All of the GN copolymeric carriers demonstrated good corneal endothelial cell and tissue compatibility. It is concluded that different types of GN-based delivery systems exhibit noticeably distinct intraocular pressure-lowering effect and miosis action, thereby reflecting the potential value of a MAA/NIPAAm molar ratio in the development of new antiglaucoma formulations. PMID:24187486

Lai, Jui-Yang

2013-01-01

248

ARGALI: an automatic cup-to-disc ratio measurement system for glaucoma detection and AnaLysIs framework  

NASA Astrophysics Data System (ADS)

Glaucoma is an irreversible ocular disease leading to permanent blindness. However, early detection can be effective in slowing or halting the progression of the disease. Physiologically, glaucoma progression is quantified by increased excavation of the optic cup. This progression can be quantified in retinal fundus images via the optic cup to disc ratio (CDR), since in increased glaucomatous neuropathy, the relative size of the optic cup to the optic disc is increased. The ARGALI framework constitutes of various segmentation approaches employing level set, color intensity thresholds and ellipse fitting for the extraction of the optic cup and disc from retinal images as preliminary steps. Following this, different combinations of the obtained results are then utilized to calculate the corresponding CDR values. The individual results are subsequently fused using a neural network. The learning function of the neural network is trained with a set of 100 retinal images For testing, a separate set 40 images is then used to compare the obtained CDR against a clinically graded CDR, and it is shown that the neural network-based result performs better than the individual components, with 96% of the results within intra-observer variability. The results indicate good promise for the further development of ARGALI as a tool for the early detection of glaucoma.

Liu, J.; Wong, D. W. K.; Lim, J. H.; Li, H.; Tan, N. M.; Wong, T. Y.

2009-02-01

249

Evaluation of a tracer release and measurement system for the detection and quantification of air emissions using the tracer ratio method  

NASA Astrophysics Data System (ADS)

The number of oil and gas production operations is increasing as is their proximity to residential areas. These facilities have been known to emit methane and other volatile organic compounds (VOCs) to the atmosphere during the different phases of development and operation. To gain a better understanding of the types and magnitude of these emissions, accurate methods for identifying and measuring the plumes released from these sources are needed. One of the most common methods for characterization of emissions is the tracer ratio. In this method, a known amount of a tracer gas is released near the potential emission source, both the tracer and the compound(s) of interest are then measured at a location downwind of the potential emissions; and the emission rate is estimated based on the ratio of the compound of interest to the tracer at the location of the measurement. This work describes field tests conducted in an air field in Fort Collins, CO to evaluate a tracer release and detection system. Acetylene (tracer gas) and methane (emission from potential source) have been released from a custom made manifold system. A PICARRO G2203 analyzer (using cavity ring down spectroscopy) and a mobile kit A0941 have been deployed on a vehicle for the downwind measurements. The emissions are measured downwind of the source and the tracer ratio method is used to calculate the emissions of methane. The measured and calculated values have been compared. Additionally, silonite-coated canisters have been used for collection and analysis of acetylene to further validate the setup. This system has been evaluated for sensitivity, accuracy and response time through a series of controlled tracer and methane releases under various meteorological conditions. The results from these tests and error analysis for the system are presented and discussed.

Hecobian, A.; Clements, A. L.; Shonkwiler, K. B.; Williams, C. M.; Wells, B. L.; MacDonald, L. P.; Pierce, J. R.; Ham, J. M.; Collett, J. L.

2013-12-01

250

Preliminary engineering report for design of a subscale ejector/diffuser system for high expansion ratio space engine testing  

NASA Technical Reports Server (NTRS)

The design of a subscale jet engine driven ejector/diffuser system is examined. Analytical results and preliminary design drawings and plans are included. Previously developed performance prediction techniques are verified. A safety analysis is performed to determine the mechanism for detonation suppression.

Wojciechowski, C. J.; Kurzius, S. C.; Doktor, M. F.

1984-01-01

251

The Golden Ratio  

NSDL National Science Digital Library

In this lesson, "students learn about ratios, including the 'Golden Ratio', a ratio of length to width that can be found in art, architecture, and nature. Students examine different ratios to determine whether the Golden Ratio can be found in the human body." (from NCTM's Illuminations) This is lesson 3 in a 7-lesson unit called "Measuring Up"

Illuminations National Council of Mathematics

2009-02-18

252

Self-forced evolutions of an implicit rotating source: A natural framework to model comparable and intermediate mass-ratio systems from inspiral through ringdown  

E-print Network

We develop a waveform model to describe the inspiral, merger and ringdown of binary systems with comparable and intermediate mass-ratios. This model incorporates first-order conservative self-force corrections to the energy and angular momentum, which are valid in the strong-field regime [1]. We model the radiative part of the self-force by deriving second-order radiative corrections to the energy flux. These corrections are obtained by minimizing the phase discrepancy between our self-force model and the effective one body model [2, 3] for a variety of mass-ratios. We show that our model performs substantially better than post-Newtonian approximants currently used to model neutron star-black hole mergers from early inspiral to the innermost stable circular orbit. In order to match the late inspiral evolution onto the plunge regime, we extend the 'transition phase' developed by Ori and Thorne [4] by including finite mass-ratio corrections and modelling the orbital phase evolution using an implicit rotating source [5]. We explicitly show that the implicit rotating source approach provides a natural transition from late-time radiation to ringdown that is equivalent to ringdown waveform modelling based on a sum of quasinormal modes.

E. A. Huerta; Prayush Kumar; Jonathan R. Gair; Sean T. McWilliams

2014-07-10

253

Male gametophyte development and two different DNA classes of pollen grains in Rumex acetosa L., a plant with an XX\\/XY 1 Y 2 sex chromosome system and a female-biased sex ratio  

Microsoft Academic Search

Female-biased sex ratio is an interesting phenomenon observed in Rumex acetosa, a dioecious plant with an XX\\/XY1Y2 sex chromosome system. Previous authors have suggested that the biased sex ratio in this species is conditioned not only\\u000a postzygotically (sex-differential sporophytic mortality) but also prezygotically, because the sex ratio of seeds is also female-biased,\\u000a although to a lesser extent than the sex

Magdalena B?ocka-Wandas; Elwira Sliwinska; Aleksandra Grabowska-Joachimiak; Krystyna Musial; Andrzej J. Joachimiak

2007-01-01

254

Simultaneous optical signal-to-noise ratio and differential group delay monitoring based on degree of polarization measurements in optical communications systems.  

PubMed

We present a simultaneous optical signal-to-noise ratio (OSNR) and differential group delay (DGD) monitoring method based on degree of polarization (DOP) measurements in optical communications systems. For the first time in the literature (to our best knowledge), the proposed scheme is demonstrated to be able to independently and simultaneously extract OSNR and DGD values from the DOP measurements. This is possible because the OSNR is related to maximum DOP, while DGD is related to the ratio between the maximum and minimum values of DOP. We experimentally measured OSNR and DGD in the ranges from 10 to 30 dB and 0 to 90 ps for a 10 Gb/s non-return-to-zero signal. A theoretical analysis of DOP accuracy needed to measure low values of DGD and high OSNRs is carried out, showing that current polarimeter technology is capable of yielding an OSNR measurement within 1 dB accuracy, for OSNR values up to 34 dB, while DGD error is limited to 1.5% for DGD values above 10 ps. For the first time to our knowledge, the technique was demonstrated to accurately measure first-order polarization mode dispersion (PMD) in the presence of a high value of second-order PMD (as high as 2071 ps(2)). PMID:22695676

Floridia, Claudio; Simões, Glauco C C P; Feres, Mariana M; Romero, Murilo A

2012-06-10

255

High ratio recirculating gas compressor  

DOEpatents

A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor.

Weinbrecht, John F. (601 Oakwood Pl., NE., Albuquerque, NM 87123)

1989-01-01

256

High ratio recirculating gas compressor  

DOEpatents

A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor. 10 figs.

Weinbrecht, J.F.

1989-08-22

257

Elucidating microbial processes in nitrate- and sulfate-reducing systems using sulfur and oxygen isotope ratios: The example of oil reservoir souring control  

NASA Astrophysics Data System (ADS)

Sulfate-reducing bacteria (SRB) are ubiquitous in anoxic environments where they couple the oxidation of organic compounds to the production of hydrogen sulfide. This can be problematic for various industries including oil production where reservoir "souring" (the generation of H 2S) requires corrective actions. Nitrate or nitrite injection into sour oil fields can promote SRB control by stimulating organotrophic nitrate- or nitrite-reducing bacteria (O-NRB) that out-compete SRB for electron donors (biocompetitive exclusion), and/or by lithotrophic nitrate- or nitrite-reducing sulfide oxidizing bacteria (NR-SOB) that remove H 2S directly. Sulfur and oxygen isotope ratios of sulfide and sulfate were monitored in batch cultures and sulfidic bioreactors to evaluate mitigation of SRB activities by nitrate or nitrite injection. Sulfate reduction in batch cultures of Desulfovibrio sp. strain Lac15 indicated typical Rayleigh-type fractionation of sulfur isotopes during bacterial sulfate reduction (BSR) with lactate, whereas oxygen isotope ratios in unreacted sulfate remained constant. Sulfur isotope fractionation in batch cultures of the NR-SOB Thiomicrospira sp. strain CVO was minimal during the oxidation of sulfide to sulfate, which had ?18O SO4 values similar to that of the water-oxygen. Treating an up-flow bioreactor with increasing doses of nitrate to eliminate sulfide resulted in changes in sulfur isotope ratios of sulfate and sulfide but very little variation in oxygen isotope ratios of sulfate. These observations were similar to results obtained from SRB-only, but different from those of NR-SOB-only pure culture control experiments. This suggests that biocompetitive exclusion of SRB took place in the nitrate-injected bioreactor. In two replicate bioreactors treated with nitrite, less pronounced sulfur isotope fractionation and a slight decrease in ?18O SO4 were observed. This indicated that NR-SOB played a minor role during dosing with low nitrite and that biocompetitive exclusion was the major process. The results demonstrate that stable isotope data can contribute unique information for understanding complex microbial processes in nitrate- and sulfate-reducing systems, and offer important information for the management of H 2S problems in oil reservoirs and elsewhere.

Hubert, Casey; Voordouw, Gerrit; Mayer, Bernhard

2009-07-01

258

New hybrid peak-to-average power ratio reduction technique based on carrier interferometry codes and companding technique for optical direct-detection orthogonal frequency division multiplexing system  

NASA Astrophysics Data System (ADS)

In direct-detection optical orthogonal frequency division multiplexing (OFDM) systems, the high peak-to-average power ratio (PAPR) will cause nonlinear effects in both electrical and optical devices and optical fiber transmission when the nonlinear amplifiers are employed. A new hybrid technique based on carrier interferometry codes and companding transform has been proposed and experimentally demonstrated to reduce the high PAPR in an optical direct-detection optical OFDM system. The proposed technique is then experimentally demonstrated and the results show the effectiveness of the new method. The PAPR of the hybrid signal has been reduced by about 5.7 dB when compared to the regular system at a complementary cumulative distribution function of 10-4. At a bit error rate of 10-4, after transmission over 100-km single-mode fiber with a ? of 2, the receiver sensitivity is improved by 3.7, 4.2, and 5 dB with launch powers of 3, 6, and 9 dBm, respectively.

Maivan, Lap; He, Jing; Chen, Ming; Mangone, Fall; Chen, Lin

2014-08-01

259

Bicycle Gears- Ratios  

NSDL National Science Digital Library

Students experiment with and learn about the gear ratios on a bicycle—thus enhancing their understanding of circumference of a circle, proportions, etc. Actual gear ratio would be the ratio between the front and rear sprocket, NOT between pedal and rear wheel.

2011-01-01

260

Study on the improved peak-to-average-power ratio reduction technology based on the partial transmission sequences method in optical orthogonal frequency division multiplexing systems  

NASA Astrophysics Data System (ADS)

According to the defect of the high peak-to-average-power ratio (PAPR) in optical orthogonal frequency division multiplexing (OFDM) systems, the PAPR reduction technology based on the partial transmission sequences (PTS) method has been deeply studied. An improved enhanced-iterative-algorithm-PTS (EIA-PTS) technology is proposed. The proposed EIA-PTS technology, compared with the original PTS (O-PTS), can reduce the computational complexity. The simulation analysis shows that the computational complexity of the O-PTS method grows exponentially with an increase in the number of both subblocks and phase factors, while the computational complexity of the EIA-PTS technology basically remains stable and is lower than that of the O-PTS method. On the basis of the proposed EIA-PTS technology, an improved EIA-PTS-Clipping combined PAPR reduction technology that combines EIA-PTS technology with clipping technology is proposed. The simulation result shows the proposed EIA-PTS-Clipping combined PAPR reduction technology, compared with the previous proposed EIA-PTS technology, can further improve the PAPR reduction performance and has a higher application value because it can have a better tradeoff between the bit error rate performance and PAPR reduction effect for optical OFDM systems.

Jianguo, Yuan; Zhangchao, Li; Yunxia, Hu; Quanliang, Sheng; Jinzhao, Lin; Yu, Pang

2014-07-01

261

An analytical system for studying the stable isotopes of carbon monoxide using continuous flow-isotope ratio mass spectrometry (CF-IRMS)  

NASA Astrophysics Data System (ADS)

In the atmosphere, carbon monoxide (CO) is the major sink for the hydroxyl radical (OH •), has multiple anthropogenic and natural sources and considerable spatial and seasonal variability. Measurements of CO isotopic composition are useful in constraining the strengths of its individual source and sink processes and thus its global cycle. A fully automated system for ?13C and ?18O analysis has been developed to extract CO from an air sample, convert CO into carbon dioxide (CO2) using the Schütze reagent, and then determine the isotopic composition in an isotope ratio mass spectrometer (IRMS). The entire system is continuously flushed with high-purity helium (He), the carrier gas. The blank signal of the Schütze reagent is only 1-3% of the typical sample size. The repeatability is 0.1‰ for ?13C and 0.2‰ for ?18O. The peak area allows simultaneous determination of the mole fraction with an analytical repeatability of ~0.7 nmol mol-1 for 100 mL of typical ambient air (185.4 nmol mol-1 of CO). A single, automated, measurement is performed in 18 min, so multiple measurements can be combined conveniently to improve precision.

Pathirana, S. L.; van der Veen, C.; Popa, M. E.; Röckmann, T.

2015-02-01

262

Design, fabrication and characterization of high-stroke high-aspect ratio micro electro mechanical systems deformable mirrors for adaptive optics  

NASA Astrophysics Data System (ADS)

Adaptive optic (AO) systems for next generation of extremely large telescopes (30--50 meter diameter primary mirrors) require high-stroke (10 microns), high-order (100x100) deformable mirrors at lower-cost than current technology. The required specifications are achievable with Micro Electro Mechanical Systems (MEMS) devices fabricated with high-aspect ratio processing techniques. This dissertation will review simulation results compared with displacement measurements of actuators utilizing a white-light interferometer. It will also review different actuator designs, materials and post-processing procedures fabricated in three different high-aspect ratio processes, Microfabrica's Electrochemical Fabrication (EFAB(TM)), HT-Micro's Precision Fabrication Technology (HTPF(TM)), and Innovative Micro Technologies (IMT) fabrication process. These manufacturing processes allow high-precision multilayer fabrication and their sacrificial layer thicknesses can be specified by the designer, rather than by constraints of the fabrication process. Various types of high-stroke gold actuators for AO consisting of folded springs with rectangular and circular membranes as well as X-beam actuators supported diagonally by beams were designed, simulated, fabricated, and tested individually and as part of a continuous facesheet DM system. The design, modeling and simulation of these actuators are compared to experimental measurements of their pull-in voltages, which characterizes their stiffness and maximum stroke. Vertical parallel plate ganged actuators fabricated with the EFAB(TM) process have a calculated pull-in voltage of 95V for a 600mum size device. In contrast, the pull-in voltages for the comb-drive actuators ranged from 55V for the large actuator, to 203V for the smallest actuator. Simulations and interferometer scans of actuator designs fabricated with HT-Micro's Precision Fabrication (HTPF(TM)) two wafer bonded process with different spring supports have shown the ability of the actuators to achieve displacements of 1/3 of the initial gap between the spring layer and the counter electrode. Actuators and DM displacement vs. voltage have been measured with an interferometer and the corresponding results were compared to Finite Element Analysis (FEA) simulations. Simulations and interferometer scans have shown the ability of the actuators to achieve displacements of greater than 1/3 of the initial gap. A stroke of ˜9.4mum has been achieved by a DM, thus showing that this fabrication process holds promise in the manufacturing of future MEMS DMs for the next generation of extremely large telescopes. A monolithic fabrication approach for integrating a faceplate on top of an actuator array from Innovative Micro Technologies has been investigated. This monolithic approach has the ability to deposit thicker layers (tens of micrometers) of structural and sacrificial materials than that of a surface micro machining processes. This fabrication process will allow the DMs to provide both high-stoke and high-order corrections, thus eliminating the need for a woofer-tweeter DM configuration. Both the actuator and the facesheet were fabricated monolithically in gold plated onto a thermally matched ceramic-glass substrate (WMS-15) using IMT's high-aspect ratio fabrication process.

Fernandez Rocha, Bautista

263

Separation of chemical constituents from three plant medicines by counter-current chromatography using a three-phase solvent system at a novel ratio.  

PubMed

A solvent system of n-hexane, methyl acetate, acetonitrile, and water at a novel volume ratio of 4:3:4:4 forms three layers, i.e. upper phase (UP), middle phase (MP), and lower phase (LP), with a volume ratio of 1:1.20:1.42 at room temperature (25°C). All three two-phases from this three-phase solvent system were successfully used to separate some chemical constituents from three plant medicines with counter-current chromatography (CCC). Eight coumarins (B1-B8) were obtained from petroleum ether extract of fresh roots of Angelica dahurica (Baizhi) with a stationary phase of UP and a mobile phase of LP. Six diarylheptanoids (L1-L6) were obtained from petroleum ether extract of dried rhizomes of Alpinia officinarum (Liangjiang) with a stationary phase of UP and a mobile phase of MP. Three chemical constituents (Z1-Z3) were obtained from ethyl acetate extract of fresh rhizomes of Anemarrhena asphodeloides (Zhimu) with a stationary phase of MP and a mobile phase of LP. Preparative HPLC was used for further purification if necessary. Seventeen chemical constituents were identified as oxypeucedanin hydrate (B1), byakangelicin (B2), byakangelicol (B3), bergapten (B4), oxypeucedanin (B5), imperatorin (B6), phellopterin (B7), isoimperatorin (B8), 5-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-heptanone (L1), 7-(4-hydroxy-3-methoxyphenyl)-1-phenyl-4E-en-3-heptanone (L2), 5-hydroxy-1,7-diphenyl-3-heptanone (L3), 1,7-diphenyl-4E-en-3-heptanone (L4), 5-hydroxy-1,7-diphenyl-4E,6E-dien-3-heptanone (L5), isomers of 1,7-diphenyl-3,5-heptandione and 5-hydroxy-1,7-diphenyl-4E-en-3-heptanone (L6), mangiferin (Z1), timosaponin A-III (Z2), and 2,6,4'-trihydroxy-4-methoxy-benzophenone (Z3) by means of MS, (1)H and (13)C NMR studies. Five compounds of B3, L3, L5, L6, and Z3 were isolated by CCC for the first time. PMID:25660525

Wu, Xiaoyi; Chao, Zhimao; Wang, Chun; Yu, Li

2015-03-01

264

Diagnostic accuracy of the magnetic resonance Parkinsonism index and the midbrain-to-pontine area ratio to differentiate progressive supranuclear palsy from Parkinson's disease and the Parkinson variant of multiple system atrophy.  

PubMed

Using magnetic resonance (MR) planimetry, both the midbrain-to-pontine area ratio (m/p-ratio) and the MR parkinsonism index (MRPI) have been shown to assist in the differential diagnosis of progressive supranuclear palsy (PSP) from Parkinson's disease (PD) and the Parkinson variant of multiple system atrophy (MSA-P). The aim of this study was to determine the diagnostic accuracy of the MRPI compared with the m/p-ratio in a large cohort of 123 patients with neurodegenerative parkinsonism including patients with PSP, PD, and MSA-P. Patients with PSP had significant higher MRPI values and significant smaller m/p-ratios compared with the other groups with overlapping individual values. Overall predictive accuracy was similar for the m/p-ratio (87.0%) and the MRPI (80.5%) with a predictive accuracy for PSP from MSA-P being significantly better for the MRPI (87.5%) compared with the m/p-ratio (75%) as well as a predictive accuracy for PSP from PD being significantly better for the m/p-ratio (87.6%) compared with the MRPI (77.3%). Both the m/p-ratio and the MRPI may assist the clinical differential diagnosis in neurodegenerative parkinsonism. PMID:20878992

Hussl, Anna; Mahlknecht, Philipp; Scherfler, Christoph; Esterhammer, Regina; Schocke, Michael; Poewe, Werner; Seppi, Klaus

2010-10-30

265

Signal-to-noise ratio of a mouse brain (13) C CryoProbe™ system in comparison with room temperature coils: spectroscopic phantom and in vivo results.  

PubMed

MRI and MRS in small rodents demand very high sensitivity. Cryogenic transmit/receive radiofrequency probes (CryoProbes) designed for (1) H MRI of mouse brain provide an attractive option for increasing the performance of small-animal MR systems. As the Larmor frequency of (13) C nuclei is four times lower than that for (1) H nuclei, an even larger sensitivity improvement is expected for (13) C applications. The aim of this work was to evaluate the performance of a prototype (13) C CryoProbe™ for mouse brain MRS. To investigate the possible gain of the (13) C CryoProbe™, we acquired localized single-voxel (13) C spectra and chemical shift images of a dimethyl sulfoxide phantom with the CryoProbe™, as well as with two room temperature resonators. The cryogenically cooled resonator achieved approximately four-fold higher signal-to-noise ratio in phantom tests when compared with the best-performing room temperature coil. In addition, we present localized (13) C spectra of mouse brain obtained with the CryoProbe™, as well as with one of the room temperature coils, demonstrating the performance in vivo. In summary, the cryogenic cooling technique significantly enhances the (13) C signal sensitivity at 9.4 T and enables the investigation of metabolism within mouse brain. PMID:24692120

Sack, M; Wetterling, F; Sartorius, A; Ende, G; Weber-Fahr, W

2014-06-01

266

Baseball Lab (Ratios)  

NSDL National Science Digital Library

Using batting averages, students will create ratios and convert them to rounded decimals (3 places). In addition, they will take decimals and determine several possible equivalent ratios. Then using the relationship that batting average = hits/at bats, the students can use proportions or equations to find either the number of hits or the number of at bats for a given situations.

2010-01-01

267

Three-dimensional analysis techniques--Part 3: Color-coded system for three-dimensional measurement of bone and ratio of soft tissue to bone: the analysis.  

PubMed

A new color-coded method of illustrating three-dimensional changes in the bone and the ratio of soft tissue to bone movement is described. The technique is illustrated by superimposing preoperative and 1-year postoperative CT scans of three patients following bimaxillary surgery. The method has proved to be a very simple, effective, and readily interpreted method of quantifying both bone and the ratio of movement of the overlying soft tissues across the face following surgery. PMID:9003912

McCance, A M; Moss, J P; Fright, W R; Linney, A D

1997-01-01

268

Note: An advanced in situ diagnostic system for characterization of electric propulsion thrusters and ion beam sources.  

PubMed

We present an advanced diagnostic system for in situ characterization of electric propulsion thrusters and ion beam sources. The system uses a high-precision five-axis positioning system with a modular setup and the following diagnostic tools: a telemicroscopy head for optical imaging, a triangular laser head for surface profile scanning, a pyrometer for temperature scanning, a Faraday probe for current density mapping, and an energy-selective mass spectrometer for beam characterization (energy and mass distribution, composition). The capabilities of our diagnostic system are demonstrated with a Hall effect thruster SPT-100D EM1. PMID:20441379

Bundesmann, C; Tartz, M; Scholze, F; Leiter, H J; Scortecci, F; Gnizdor, R Y; Neumann, H

2010-04-01

269

Simplifying Likelihood Ratios  

PubMed Central

Likelihood ratios are one of the best measures of diagnostic accuracy, although they are seldom used, because interpreting them requires a calculator to convert back and forth between “probability” and “odds” of disease. This article describes a simpler method of interpreting likelihood ratios, one that avoids calculators, nomograms, and conversions to “odds” of disease. Several examples illustrate how the clinician can use this method to refine diagnostic decisions at the bedside.

McGee, Steven

2002-01-01

270

Isotope Ratio Mass Spectrometry.  

PubMed

Isotope Ratio Mass Spectrometry (IRMS) is a specialized technique used to provide information about the geographic, chemical, and biological origins of substances. The ability to determine the source of an organic substance stems from the relative isotopic abundances of the elements which comprise the material. Because the isotope ratios of elements such as carbon, hydrogen, oxygen, sulfur, and nitrogen can become locally enriched or depleted through a variety of kinetic and thermodynamic factors, measurement of the isotope ratios can be used to differentiate between samples which otherwise share identical chemical compositions. Several sample introduction methods are now available for commercial isotope ratio mass spectrometers. Combustion is most commonly used for bulk isotopic analysis, whereas gas and liquid chromatography are predominately used for the real-time isotopic analysis of specific compounds within a mixture. Here, highlights of advances in instrumentation and applications within the last three years are provided to illustrate the impact of this rapidly growing area of research. Some prominent new applications include authenticating organic food produce, ascertaining whether or not African elephants are guilty of night-time raids on farmers' crops, and linking forensic drug and soil samples from a crime scene to a suspected point of origin. For the sake of brevity, we focus this Minireview on the isotope ratio measurements of lighter-elements common to organic sources; we do not cover the equally important field of inorganic isotope ratio mass spectrometry. PMID:19173039

Muccio, Zeland; Jackson, Glen P

2009-02-01

271

Effects of melt composition on Fe3+/Fe2+ in silicate melts: a step to model ferric/ferrous ratio in multicomponent systems  

NASA Astrophysics Data System (ADS)

The effect of Al2O3, MgO and total iron on the ferric/ferrous ratio in silicate melts was investigated in model silicate melts in the temperature range 1400-1550 °C at 1 atm total pressure. The experiments were done mostly in air and partially in pure CO2. It is demonstrated that an increase in Al2O3 concentration in a basaltic melt results in a moderate decrease of Fe3+/Fe2+ ratio. In contrast, the increase in Al2O3 in more silicic melts results in a much more pronounced decrease of Fe3+/Fe2+ ratio. The increase of MgO concentration in a basaltic melt results in a moderate increase of Fe3+/Fe2+ ratio but has a negligible effects in more silicic melts. The different behavior of Al2O3 and MgO in basaltic and more silicic melts indicates that at constant T- fO2 conditions, the effects of melt composition on ferric/ferrous ratio cannot be predicted accurately as a function of ? d i X i where d i are fixed empirical coefficients and X i are mole fractions of the main oxide component in silicate melts. We suggest an alternative approach which accounts for the interaction of cations in complex silicate melts. Based on the data obtained in this study, an equation predicting the ferric/ferrous ratio of ultramafic to silicic melts at air conditions with changing SiO2, TiO2, Al2O3, total iron, MgO and P2O5 is proposed.

Borisov, Alexander; Behrens, Harald; Holtz, Francois

2015-02-01

272

Informal uncertainty analysis (GLUE) of continuous flow simulation in a hybrid sewer system with infiltration inflow - consistency of containment ratios in calibration and validation?  

NASA Astrophysics Data System (ADS)

Monitoring of flows in sewer systems is increasingly applied to calibrate urban drainage models used for long-term simulation. However, most often models are calibrated without considering the uncertainties. The generalized likelihood uncertainty estimation (GLUE) methodology is here applied to assess parameter and flow simulation uncertainty using a simplified lumped sewer model that accounts for three separate flow contributions: wastewater, fast runoff from paved areas, and slow infiltrating water from permeable areas. Recently GLUE methodology has been critisised for generating prediction limits without statistical coherence and consistency and for the subjectivity in the choice of a threshold value to distinguish "behavioural" from "non-behavioural" parameter sets. In this paper we examine how well the GLUE methodology performs when the behavioural parameter sets deduced from a calibration period are applied to generate prediction bounds in validation periods. By retaining an increasing number of parameter sets we aim at obtaining consistency between the GLUE generated 90% prediction limits and the actual containment ratio (CR) in calibration. Due to the large uncertainties related to spatio-temporal rain variability during heavy convective rain events, flow measurement errors, possible model deficiencies as well as epistemic uncertainties, it was not possible to obtain an overall CR of more than 80%. However, the GLUE generated prediction limits still proved rather consistent, since the overall CRs obtained in calibration corresponded well with the overall CRs obtained in validation periods for all proportions of retained parameter sets evaluated. When focusing on wet and dry weather periods separately, some inconsistencies were however found between calibration and validation and we address here some of the reasons why we should not expect the coverage of the prediction limits to be identical in calibration and validation periods in real-world applications. The large uncertainties result in wide posterior parameter limits, that cannot be used for interpretation of, for example, the relative size of paved area vs. the size of infiltrating area. We should therefore try to learn from the significant discrepancies between model and observations from this study, possibly by using some form of non-stationary error correction procedure, but it seems crucial to obtain more representative rain inputs and more accurate flow observations to reduce parameter and model simulation uncertainty.

Breinholt, A.; Grum, M.; Madsen, H.; Örn Thordarson, F.; Mikkelsen, P. S.

2013-10-01

273

A new action potential detector using the MTEO and its effects on spike sorting systems at low signal-to-noise ratios  

Microsoft Academic Search

This paper considers neural signal processing applied to extracellular recordings, in particular, unsupervised action potential detection at a low signal-to-noise ratio. It adopts the basic framework of the multiresolution Teager energy operator (MTEO) detector, but presents important new results including a significantly improved MTEO detector with some mathematical analyses, a new alignment technique with its effects on the whole spike

Joon Hwan Choi; Hae Kyung Jung; Taejeong Kim

2006-01-01

274

Inherent correlation between the total output cooling capacity and equipment sensible heat ratio of a direct expansion air conditioning system under variable-speed operation (XXG SMD SHR DX AC unit)  

Microsoft Academic Search

Appropriately controlling indoor air humidity at a suitable level in buildings is important. To simultaneously control both indoor air dry-bulb temperature and relative humidity requires the match between the total output cooling capacity of an A\\/C system and the total cooling load in a space served by the A\\/C system, as well as the Equipment sensible heat ratio (SHR) of

Xiangguo Xu; Liang Xia; Mingyin Chan; Shiming Deng

2010-01-01

275

Weather-Corrected Performance Ratio  

SciTech Connect

Photovoltaic (PV) system performance depends on both the quality of the system and the weather. One simple way to communicate the system performance is to use the performance ratio (PR): the ratio of the electricity generated to the electricity that would have been generated if the plant consistently converted sunlight to electricity at the level expected from the DC nameplate rating. The annual system yield for flat-plate PV systems is estimated by the product of the annual insolation in the plane of the array, the nameplate rating of the system, and the PR, which provides an attractive way to estimate expected annual system yield. Unfortunately, the PR is, again, a function of both the PV system efficiency and the weather. If the PR is measured during the winter or during the summer, substantially different values may be obtained, making this metric insufficient to use as the basis for a performance guarantee when precise confidence intervals are required. This technical report defines a way to modify the PR calculation to neutralize biases that may be introduced by variations in the weather, while still reporting a PR that reflects the annual PR at that site given the project design and the project weather file. This resulting weather-corrected PR gives more consistent results throughout the year, enabling its use as a metric for performance guarantees while still retaining the familiarity this metric brings to the industry and the value of its use in predicting actual annual system yield. A testing protocol is also presented to illustrate the use of this new metric with the intent of providing a reference starting point for contractual content.

Dierauf, T.; Growitz, A.; Kurtz, S.; Cruz, J. L. B.; Riley, E.; Hansen, C.

2013-04-01

276

The Likelihood Ratio Test  

NSDL National Science Digital Library

This module, created by Don Johnson of Rice University, provides an explanation and an example of the likelihood ratio test. Topics include: decision regions, Bayes' decision criterion, Bayes' cost, and likelihood function. The site is enhanced by Johnson's use of graphic and numerical demonstrations to better explain his points. Additionally, a PDF attachment providing an in-depth explanation is also featured.

Johnson, Don

277

Formation and Evolution of the Disk System of the Milky Way: [alpha/Fe] Ratios and Kinematics of the SEGUE G-Dwarf Sample  

SciTech Connect

We employ measurements of the [{alpha}/Fe] ratio fromlow-resolution (R {approx} 2000) spectra of 17,500 G-type dwarfs included in SDSS Data Release 8, selected using simple and well-understood selection criteria, to separate them into likely thin- and thick-disk subsamples. This classification, based on chemistry, is strongly motivated by the bi-modal distribution of stars in the [{alpha}/Fe] vs. [Fe/H] diagram. The resulting subsamples allow, for the first time, investigations of the kinematic behavior of thin- and thick-disk stars as a function of metallicity and position up to distances of 3 kpc from the Galactic plane. Both subsamples exhibit strong gradients of orbital rotational velocity with metallicity, but with opposite signs (-20 to -30 km s{sup -1} dex{sup -1} for the thin-disk population, and +40 to +50 km s{sup -1} dex{sup -1} for the thick-disk population). We find that the rotational velocity decreases with the distance from the plane for both disk components, with similar slopes (10 km s{sup -1} kpc{sup -1}), and a nearly constant difference in the mean rotational velocity of about 30 km s{sup -1}. The mean rotational velocity is uncorrelated with Galactocentric distance for the thin-disk subsample, and exhibits only a marginally significant correlation for the thick-disk subsample. Thick-disk stars exhibit a very strong trend of orbital eccentricity with metallicity (-0.2 dex{sup -1}), while the eccentricity does not change with metallicity for the thin-disk subsample. The eccentricity is almost independent of Galactocentric radius for the thin-disk stars, while a marginal gradient of the eccentricity with distance exists for the thick-disk population. Both subsamples possess similar trends of increasing eccentricity with distance from the Galactic plane, with a constant difference of about 0.1. The shapes of the overall distributions of orbital eccentricity for the thin- and thick-disk populations are quite different from one another, independent of distance from the plane; neither subsample has significant numbers of stars with eccentricity above 0.6. These observational results provide strong new constraints on models for the formation and evolution of the Milky Way's disk system. For example, the observed dependence of the mean rotational velocity on metallicity for thin-disk stars is inconsistent with predictions from classical local chemical evolution models. We also consider the predictions of several contemporary models of disk evolution, such as radial migration, gas-rich mergers, disk heating, and pure accretion models. We find that radial migration appears to have played an important role in the evolution of the thin-disk population, but possibly less so, relative to the gas-rich merger or disk heating scenarios, for the thick disk. Pure accretion models appear to be ruled out by the observed distribution of eccentricities for thick-disk stars. We emphasize that more physically realistic models, and simulations that probe a greater range of disk formation scenarios, need to be constructed in order to carry out the detailed quantitative comparisons that our new data enable.

Lee, Young Sun; /Michigan State U.; Beers, Timothy C.; /Michigan State U.; An, Deokkeun; /Ewha Women's U., Seoul; Ivezic, Zeljko; /Washington U., Seattle, Astron. Dept.; Just, Andreas; /Heidelberg U.; Rockosi, Constance M.; /Lick Observ.; Morrison, Heather L.; /Case Western Reserve U.; Johnson, Jennifer A.; /Ohio State U.; Schonrich, Ralph; /Garching, Max Planck Inst.; Bird, Jonathan; /Ohio State U.; Yanny, Brian; /Fermilab /Case Western Reserve U.

2011-04-01

278

A Modified Magnitude System that Produces Well-Behaved Magnitudes, Colors, and Errors Even for Low Signal-to-Noise Ratio Measurements  

E-print Network

We describe a modification of the usual definition of astronomical magnitudes, replacing the usual logarithm with an inverse hyperbolic sine function; we call these modified magnitudes `asinh magnitudes'. For objects detected at signal-to-noise ratios of greater than about five, our modified definition is essentially identical to the traditional one; for fainter objects (including those with a formally negative flux) our definition is well behaved, tending to a definite value with finite errors as the flux goes to zero. This new definition is especially useful when considering the colors of faint objects, as the difference of two `asinh' magnitudes measures the usual flux ratio for bright objects, while avoiding the problems caused by dividing two very uncertain values for faint objects. The Sloan Digital Sky Survey (SDSS) data products will use this scheme to express all magnitudes in their catalogs.

Robert Lupton; Jim Gunn; Alex Szalay

1999-03-04

279

Rheological, morphological, thermal, and mechanical properties of blends of vectra A950 and poly(trimethylene terephthalate): A study on a high-viscosity-ratio system  

Microsoft Academic Search

Poly(trimethylene terephthalate) (PTT) and a liquid crystalline polymer, Vectra A950 (VA), were melt-blended and subjected to capillary rheometry. Effects of VA content, shear rate and temperature on viscosity and flow activation energy (Ea) were investigated. Partial fibrillation was found even though the viscosity ratio was greater than one, leading to the formation of in-situ composites. Thermal and thermogravimetric analysis of

Penwisa Pisitsak; Rathanawan Magaraphan

2009-01-01

280

Automated airway evaluation system for multi-slice computed tomography using airway lumen diameter, airway wall thickness and broncho-arterial ratio  

NASA Astrophysics Data System (ADS)

Pulmonary diseases such as bronchiectasis, asthma, and emphysema are characterized by abnormalities in airway dimensions. Multi-slice computed tomography (MSCT) has become one of the primary means to depict these abnormalities, as the availability of high-resolution near-isotropic data makes it possible to evaluate airways at oblique angles to the scanner plane. However, currently, clinical evaluation of airways is typically limited to subjective visual inspection only: systematic evaluation of the airways to take advantage of high-resolution data has not proved practical without automation. We present an automated method to quantitatively evaluate airway lumen diameter, wall thickness and broncho-arterial ratios. In addition, our method provides 3D visualization of these values, graphically illustrating the location and extent of disease. Our algorithm begins by automatic airway segmentation to extract paths to the distal airways, and to create a map of airway diameters. Normally, airway diameters decrease as paths progress distally; failure to taper indicates abnormal dilatation. Our approach monitors airway lumen diameters along each airway path in order to detect abnormal profiles, allowing even subtle degrees of pathologic dilatation to be identified. Our method also systematically computes the broncho-arterial ratio at every terminal branch of the tree model, as a ratio above 1 indicates potentially abnormal bronchial dilatation. Finally, the airway wall thickness is computed at corresponding locations. These measurements are used to highlight abnormal branches for closer inspection, and can be summed to compute a quantitative global score for the entire airway tree, allowing reproducible longitudinal assessment of disease severity. Preliminary tests on patients diagnosed with bronchiectasis demonstrated rapid identification of lack of tapering, which also was confirmed by corresponding demonstration of elevated broncho-arterial ratios.

Odry, Benjamin L.; Kiraly, Atilla P.; Novak, Carol L.; Naidich, David P.; Lerallut, Jean-Francois

2006-03-01

281

What's My Ratio?  

NSDL National Science Digital Library

In this activity, students use linear measurement and calculators to investigate proportionality and determine the constant ratio between similar figures. In it, students draw a figure on centimeter graph paper, increase or decrease the size, and predict the dimensions. Then students compare the ratio of two pictures by measuring, recording their data, and discussing their findings to draw conclusions. Suggested guidelines for instruction and classroom discussion are included, as well as data collection worksheets for students, and centimeter graph paper to print. The lesson may be introduced by reading appropriate sections from "Goosebumps—Monster Blood III" (Chapters 15 and 16) by R.L. Stine, or "The Shrinking of Treehorn" by F. Heide.

2010-06-30

282

Displacement and Velocity Ratios  

NSDL National Science Digital Library

This interactive presentation, created by James Bourassa and John Rosz for the Electromechanical Digital Library, discusses displacement and velocity ratios. Bourassa and Rosz begin by providing detailed definitions of both topics and then provide mathematical examples of each. Once this basic explanation is complete, the authors allow students to practice these theories in a set of self-correcting quiz questions. Bourassa and Rosz explain each using helpful interactive flash animations. These are not only useful in explanation, but they allow the student to more fully engage with the topic. Overall, this is a nice introduction to the physical and mathematical concepts of displacement and velocity ratios. This could be a valuable learning resource in everything from a physics to a technical education classroom.

Bourassa, James

283

HEAVY ION FUSION SCIENCE VIRTUAL NATIONAL LABORATORY2nd QUARTER 2010 MILESTONE REPORTDevelop the theory connecting pyrometer and streak camera spectrometer data to the material properties of beam heatedtargets and compare to the data  

SciTech Connect

This milestone has been accomplished. We have extended the theory that connects pyrometer and streak spectrometer data to material temperature on several fronts and have compared theory to NDCX-I experiments. For the case of NDCX-I, the data suggests that as the metallic foils are heated they break into droplets (cf. HIFS VNL Milestone Report FY 2009 Q4). Evaporation of the metallic surface will occur, but optical emission should be directly observable from the solid or liquid surface of the foil or from droplets. However, the emissivity of hot material may be changed from the cold material and interference effects will alter the spectrum emitted from small droplets. These effects have been incorporated into a theory of emission from droplets. We have measured emission using streaked spectrometry and together with theory of emission from heated droplets have inferred the temperature of a gold foil heated by the NDCX-I experiment. The intensity measured by the spectrometer is proportional to the emissivity times the blackbody intensity at the temperature of the foil or droplets. Traditionally, a functional form for the emissivity as a function of wavelength (such as a quadratic) is assumed and the three unknown emissivity parameters (for the case of a quadratic) and the temperature are obtained by minimizing the deviations from the fit. In the case of the NDCX-I experiment, two minima were obtained: at 7200 K and 2400 K. The best fit was at 7200 K. However, when the actual measured emissivity of gold was used and when the theoretical corrections for droplet interference effects were made for emission from droplets having radii in the range 0.2 to 2.0 microns, the corrected emissivity was consistent with the 2400 K value, whereas the fit emissivity at 7200 K shows no similarity to the corrected emissivity curves. Further, an estimate of the temperature obtained from beam heating is consistent with the lower value. This exercise proved to be a warning to be skeptical of assuming functional forms when they are unknown, and also represents a first success of the droplet emission theory. The thermal optical emission from a hot metal surface is polarized (for observation angles that are not normal to the surface). By observing the intensity of both polarizations at two or more observation angles the emissivity can be inferred directly, and the temperature at the surface unambiguously determined. Emission from the spolarization (where the E-field is parallel to the surface and normal to the wave vector) is generally less intense than emission from the p-polarization (E-field that is normal to the s-polarization E-field and the wave vector.) The emissivity and temperature may be inferred directly without assuming any specific functional form for the emissivity or resorting to published data tables (which usually do not apply when temperatures reach the WDM regime). We have derived the theory of polarized emission from hot metals, and consider an improved method of temperature determination that takes advantage of polarization measurements, which we call polarization pyrometry. Thus far we have successfully applied the theory to electrically heated metallic filaments, and will apply the theory to beam heated targets when chamber space constraints are removed that will make it feasible to observe the targets at multiple angles. For the case of experiments on NDCX-II, hydrodynamic expansion on a nanosecond timescale that is comparable to the heating time will result in an expanding fluid, with a strong (but finite) density and temperature gradient. Emission will be observed from positions in the foil near the critical density (where the observation photon frequency is equal to the local plasma frequency). By assuming a brightness temperature equal to the local fluid temperature at the critical frequency, a time history of the emission spectrum from an expanding foil can be synthesized from a hydrodynamic simulation of the target. We find that observations from the ultraviolet to the infrared will allow a probing of the target at dif

More, R.M.; Barnard, J. J.; Bieniosek, F.M.; Henestroza, E.; Lidia, S. M.; Ni, P. A.

2010-04-01

284

Ratios and Proportions  

NSDL National Science Digital Library

This interactive slideshow explains the notion of ratios and proportions, how to write the, and how to find them. There are practice problems which walk visitors through each step of the process, including reducing answers to simplest terms, in which students are asked to calculate the rate of grass seed coverage per square foot and find the miles per gallon fuel use of a car. The lesson continues on to introduce proportion and work through practice problems in the same fashion.

Douglas Jensen

2005-01-01

285

Handy Measuring Ratio  

NSDL National Science Digital Library

In this activity, learners use their hands as tools for indirect measurement. Learners explore how to use ratios to calculate the approximate height of something that can't be measured directly by first measuring something that can be directly measured. This activity can also be used to explain how scientists use indirect measurement to determine distances between things in the universe that are too far away, too large or too small to measure directly (i.e. diameter of the moon or number of bacteria in a volume of liquid).

2012-08-23

286

Analysis of NO3 interception of the parasitic angiosperm Orobanche spp. using a positron-emitting tracer imaging system and NO 3: A new method for the visualization and quantitative analysis of the NO3 interception ratio  

Microsoft Academic Search

The root parasitic plants Orobanche spp. (broomrapes) seriously affect agricultural production. A visualization and quantitative analytical method for the interception of nutrients was established using a positron-emitting tracer imaging system and NO 3. By using this analytical method that involves volume normalization with F images, the nitrogen nutrient interception ratio of the Orobanche spp. was calculated to be 73.6 ± 3.9% in

Naoki Kawachi; Shu Fujimaki; Koichi Sakamoto; Noriko S. Ishioka; Simpei Matsuhashi; Hitoshi Sekimoto

2008-01-01

287

Infinitely variable ratio transmission  

SciTech Connect

A variable ratio vehicle transmission is described whose gear ratio is determined essentially only by torque on the output shaft of the transmission, comprising: a housing fixed in the vehicle; a power input shaft entering one end of the housing; a power output shaft entering the other end of the housing; a planet carrier mounted concentrically on the input shaft; a planet shaft mounted rotatably to the planet carrier; planet gears fixed coaxially to the planet shaft, one planet gear being a power transferring gear, a second planet gear being a reaction planet gear; a brake means rotatable about the input shaft sleeve for controlling the rate of rotation of the reaction planet gear about the planet shaft axis when the reaction planet gear orbits about the input shaft axis, the brake means having an inhibitor means for providing a substantially constant drag against rotation of the brake means about the input shaft; the brake means having a disk-like wall encircling the input shaft and a brake gear meshed with the reaction planet gear; the inhibitor means having two sets of annular friction disks disposed between the disk-like wall and the one end of the housing; the transmission further comprising means for operatively connecting the transferring planet gear to the output shaft.

Geppert, E.F.

1989-02-21

288

Ratios For All Occasions  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards.A central theme in the middle school mathematics curriculum, proportional reasoning is based on making sense of ratios in a variety of contexts. The resources chosen for this unit provide practice in solving problems, often informally, in the format of games, hands-on modeling, mapmaking, and questions selected for their interest for students. As students work through the activities, they will exercise reasoning about basic proportions as ell as further develop their knowledge of the relationship between fractions and percents.The section titled Background Resources for Teachers contains links to workshop sessions, developed for teachers, on the mathematical content of the unit. Ratios in Childrens Books identifies three picture books that entertain while they explore scale and proportion. In the final section, we look at the coverage of proportionality at the iddle level in the NCTM Principles and Standards for School Mathematics.

Terese Herrera

289

Estimating evapotranspiration using remote sensing: A hybrid approach between MODIS derived enhanced vegetation index, Bowen ratio system, and ground based micro-meteorological data  

NASA Astrophysics Data System (ADS)

We investigated water loss by evapotranspiration (ET) from the Palo Verde Irrigation District (PVID) and the Cibola National Wildlife Refuge (CNWR) in southern California bordering the Colorado River collaborating with the United States Bureau of Reclamation (U.S.B.R.). We developed an empirical model to estimate ET for the entire PVID using satellite derived MODIS enhanced vegetation index (EVI), and ground based measurements of solar radiation and vapor pressure. We compared our predictions with U.S.B.R. estimates through statistical cross validation and showed they agree with an error less than 8%. We tested the same model for an alfalfa field inside PVID to check its applicability at a smaller spatial scale. We showed that the same model developed for PVID is the best model for estimating ET for the alfalfa field. We collected data from three Bowen ratio energy balance (BREB) towers installed in the invasive saltcedar (Tamarix spp) dominated riparian zone in the CNWR and a fourth tower in the alfalfa field in PVID. The riparian sites were selected according to different densities of vegetation. We collected data from these sites at various intervals during the period between June 2006 to November 2008. We reduced the errors associated with the Bowen ratio data using statistical procedures taking into account occasional instrument failures and problems inherent in the BREB method. Our results were consistent with vegetation density and estimates from MODIS EVI images. To estimate ET for larger patches of mixed vegetation we modified the crop coefficient equation and represented it in terms of EVI. Using this approach, we scaled the alfalfa field data to the entire PVID and compared the results with U.S.B.R. (2001-2007) estimates. We predicted ET well within the acceptable range established in the literature. We empirically developed ET models for the riparian tower sites to provide accurate point scale ET estimation and scaled for the entire riparian region in CNWR with our modified crop coefficient approach. We investigated the assumptions upon which the Bowen ratio equation is developed. In the presence of turbulence some of the assumptions may not be valid, and the final data may require correction factors.

Chatterjee, Sumantra

290

Central Nervous System Effects of the Second-Generation Antihistamines Marketed in Japan -Review of Inter-Drug Differences Using the Proportional Impairment Ratio (PIR)-  

PubMed Central

Background Second-generation antihistamines (AHs) have, in general, fewer sedative effects than the first-generation. However, important inter-drug differences remain in the degree of cognitive and/or psychomotor impairment. The extent to which a particular compound causes disruption can be conveniently compared, to all other AHs, using the Proportional Impairment Ratio (PIR). Although the PIR can differentiate the relative impairment caused by individual drugs, there is no indication of the reliability of the ratios obtained. Objective To calculate the PIRs –together with 95% confidence intervals (CIs), as an index of reliability– and compare AHs currently, or soon to be, available in Japan, with respect to their intrinsic capacity to cause impairment. Methods Results from studies of cetirizine, desloratadine, ebastine, fexofenadine, levocetirizine, loratadine, mequitazine, and olopatadine were included in the PIR calculations. All data utilised came from crossover studies in healthy volunteers which were randomised and placebo and positive-internal controlled. Existing databases from studies reporting the sedative effects of AHs on objective (speed, accuracy, memory) and subjective (feeling) psychometrics were augmented, via results from suitable studies published after the previous reviews. The null value for a PIR was one. Results A total of 45 studies were finally included for this review. Of the AHs assessed, fexofenadine, ebastine, and levocetirizine showed a PIR for objective tests of 0. However, only fexofenadine (PIR?=?0.49) had an upper limit of the 95% CI of less than 1. Fexofenadine, levocetirizine, desloratadine, olopatadine, loratadine, and mequitazine all had a PIR for subjective ratings of 0, but the upper limits of the 95% CIs were all in excess of 1, although fexofenadine (PIR?=?2.57) was the lowest. Conclusions The results show that there are differences between second-generation AHs in the extent of sedation produced. However, subjective ratings indicate that patients may not necessarily be aware of this. PMID:25501360

Isomura, Tatsuya; Kono, Takeshi; Hindmarch, Ian; Kikuchi, Norimasa; Murakami, Aya; Inuzuka, Kyoko; Kawana, Seiji

2014-01-01

291

Lorentz ratio of quantum plasmas  

SciTech Connect

A quantum collective approach is developed to investigate linear transport properties of a system of highly degenerate weakly coupled electrons and strongly coupled semiclassical ions. The basic formalism rests upon suitable extention of the Boltzmann--Bloch quantum transport equation. The model considers electron--ion (e--i) and electron--electron (e--e) collisions in a unified scheme of both long- and short-range Coulomb interactions. The e--e collisions contribute to the thermal conductivity calculation in the low coupling regime. Even though they can be insignificant for strongly coupled systems, the extensively used Lorentz gas approximation cannot be justified for plasmas of astrophysical interests. It is shown that the Lorentz ratio of high-density plasma may exhibit substantial negative deviation from the ideal Sommerfeld value, due to some nonidealities, such as e--e interaction and quantum effects. Results are presented under analytical and compact forms allowing numerical applications, as well as comparisons with existing theories.

Khalfaoui, A.; Bennaceur, D. (Centre de Developpement des Technologies Avancees, Laboratoire Interaction Laser-Matiere, 2 Bd Franz Fanon, BP 1017 Alger-gare 16000 (Algeria))

1994-06-01

292

Peak power ratio generator  

DOEpatents

A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

Moyer, Robert D. (Albuquerque, NM)

1985-01-01

293

Ratio and Proportion  

NSDL National Science Digital Library

This interactive Flash applet helps students explore concepts of ratio and proportion. It displays two containers, each with its own tap that can be set to deliver different-colored liquids in units of 1 to 10. A main tap can be set to deliver multiples of the amounts on the left- and right-hand taps. Proportion can be modelled using the drain container, which receives whatever is in the left- and right-hand containers. Users can choose the capacity of the containers, whether to hide or show the scales, and the size and visibility of the drain container. Clicking on the info button allows users to mouse over items to learn about them. This applet lends itself well for use with an interactive white board. A pdf guide to this collection of teaching applets is cataloged separately.

2006-01-01

294

Low porosity metallic periodic structures with negative Poisson's ratio.  

PubMed

Auxetic behavior in low porosity metallic structures is demonstrated via a simple system of orthogonal elliptical voids. In this minimal 2D system, the Poisson's ratio can be effectively controlled by changing the aspect ratio of the voids. In this way, large negative values of Poisson's ratio can be achieved, indicating an effective strategy for designing auxetic structures with desired porosity. PMID:24375708

Taylor, Michael; Francesconi, Luca; Gerendás, Miklós; Shanian, Ali; Carson, Carl; Bertoldi, Katia

2014-04-16

295

Numerical simulations of the evolution of Taylor cells from a growing boundary layer on the inner cylinder of a high radius ratio Taylor-Couette system.  

PubMed

The Taylor-Couette flow in the gap between two concentric cylinders has been studied numerically to show the evolution of Taylor vortices from pairs of ring-shaped vortices, at Reynolds numbers of 5 x 10(3) and 8 x 10(3) based upon the gap width. The cylinders have a high radius ratio of 0.985 and the inner cylinder rotates within a stationary outer cylinder. Initially, ring-shaped vortices are generated at the surface of the inner cylinder and spread into the gap. This is distinctly different from the formation of laminar Taylor vortices that grow from the end walls. Mixing of these ring-shaped vortices with the developing Couette flow then occurs and further ring-shaped vortices are generated. Some of these dominate the flow and begin to form Taylor vortices. Finally the Taylor vortices are stabilized and further vortex formation ceases. An analysis is also presented of the variation of shear stress with time. PMID:12513397

Batten, W M J; Bressloff, N W; Turnock, S R

2002-12-01

296

Correlation of infrared reflectance ratios at 2.3 microns/1.6 micron and 1.1 micron/1.6 micron with delta O-18 values delineating fossil hydrothermal systems in the Idaho batholith  

NASA Technical Reports Server (NTRS)

Reflectance ratios from laboratory spectra and airborne multispectral images are found to be strongly correlated with delta O-18 values of granite rocks in the Idaho batholith. The correlation is largely a result of interactions between hot water and rock, which lowered the delta O-18 values of the rocks and produced secondary hydrous material. Maps of the ratio of reflectivities at 2.3 and 1.6 microns should delineate fossil hydrothermal systems and provide estimates of alteration intensity. However, hydrous minerals produced during deuteric alteration or weathering cannot be unambiguously distinguished in remotely sensed images from the products of propylitic alteration without the use of narrow-band scanners. The reflectivity at 1.6 micron is strongly correlated with rock density and may be useful in distinguishing rock types in granitic terranes.

Gillespie, A. R.; Criss, R. E.

1983-01-01

297

Negative Poisson's ratio materials via isotropic interactions.  

PubMed

We show that under tension a classical many-body system with only isotropic pair interactions in a crystalline state can, counterintuitively, have a negative Poisson's ratio, or auxetic behavior. We derive the conditions under which the triangular lattice in two dimensions and lattices with cubic symmetry in three dimensions exhibit a negative Poisson's ratio. In the former case, the simple Lennard-Jones potential can give rise to auxetic behavior. In the latter case, a negative Poisson's ratio can be exhibited even when the material is constrained to be elastically isotropic. PMID:18764632

Rechtsman, Mikael C; Stillinger, Frank H; Torquato, Salvatore

2008-08-22

298

Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: A review and examples from principal aquifers in the United States  

NASA Astrophysics Data System (ADS)

SummaryA detailed review was made of chemical indicators used to identify impacts from septic tanks on groundwater quality. Potential impacts from septic tank leachate on groundwater quality were assessed using the mass ratio of chloride-bromide (Cl/Br), concentrations of selected chemical constituents, and ancillary information (land use, census data, well depth, soil characteristics) for wells in principal aquifers of the United States. Chemical data were evaluated from 1848 domestic wells in 19 aquifers, 121 public-supply wells in 6 aquifers, and associated monitoring wells in four aquifers and their overlying hydrogeologic units. Based on previously reported Cl/Br ratios, statistical comparisons between targeted wells (where Cl/Br ratios range from 400 to 1100 and Cl concentrations range from 20 to 100 mg/L) and non-targeted wells indicated that shallow targeted monitoring and domestic wells (<20 m depth below land surface) had a significantly ( p < 0.05) higher median percentage of houses with septic tanks (1990 census data) than non-targeted wells. Higher ( p = 0.08) median nitrate-N concentration (3.1 mg/L) in oxic (dissolved oxygen concentrations >0.5 mg/L) shallow groundwater from target domestic wells, relative to non-target wells (1.5 mg/L), corresponded to significantly higher potassium, boron, chloride, dissolved organic carbon, and sulfate concentrations, which may also indicate the influence of septic-tank effluent. Impacts on groundwater quality from septic systems were most evident for the Eastern Glacial Deposits aquifer and the Northern High Plains aquifer that were associated with the number of housing units using septic tanks, high permeability of overlying sediments, mostly oxic conditions, and shallow wells. Overall, little or no influence from septic systems were found for water samples from the deeper public-supply wells. The Cl/Br ratio is a useful first-level screening tool for assessing possible septic tank influence in water from shallow wells (<20 m) with the range of 400-1100. The use of this ratio would be enhanced with information on other chloride sources, temporal variability of chloride and bromide concentrations in shallow groundwater, knowledge of septic-system age and maintenance, and the use of multiple tracers (combination of additional chemical and microbiological indicators).

Katz, Brian G.; Eberts, Sandra M.; Kauffman, Leon J.

2011-02-01

299

Poisson's ratio and crustal seismology  

Microsoft Academic Search

New measurements of compressional and shear wave velocities to hydrostatic pressures of 1 GPa are summarized for 678 rocks. Emphasis was placed on obtaining high-accuracy velocity measurements, which are shown to be critical in calculating Poisson's ratios from velocities. The rocks have been divided into 29 major groups for which velocities, velocity ratios, and Poisson's ratios are presented at several

Nikolas I. Christensen

1996-01-01

300

Climatic significance of isotope ratios  

Microsoft Academic Search

The hydrogen and oxygen isotope ratios of water, which can be measured by Isotope Ratio Mass Spectrometry (IRMS), exhibit climatic dependencies and are commonly exploited in hydrogeology. More generally, the overall carbon or hydrogen isotope ratios of plant organic matter, and in particular of tree-ring cellulose, have been frequently used for climatic reconstruction. However, since many physicochemical and biochemical fractionation

Gérard J. Martin; Maryvonne L. Martin

2003-01-01

301

Estimating CE ratios under second-order uncertainty: the mean ratio versus the ratio of means.  

PubMed

Two methods have been presented for estimating cost-effectiveness ratios under conditions of second-order (model) uncertainty: one method estimates a mean ratio of cost to effect (the "mean ratio" approach), and the other estimates a ratio of mean cost to mean effect (the "ratio of means" approach). However, the question of which estimate is theoretically correct has not been formally addressed. The authors show that the "ratio of means" approach follows directly from the theoretical foundations of cost-effectiveness analysis, has attractive internal consistency properties, and is consistent with a simple vector algebra approach to the problem. In contrast, the "mean ratio" approach has not been shown to follow from first principles, is internally inconsistent, and can prescribe economically inefficient choices. It is concluded that the "ratio of means" procedure should be preferred unless persuasive arguments are presented to the contrary. PMID:9343807

Stinnett, A A; Paltiel, A D

1997-01-01

302

Versatile inlet system for on-line compound-specific deltaD and delta13C gas chromatography-oxidation/reduction-isotope ratio mass spectrometry analysis of gaseous mixtures.  

PubMed

Compound-specific deltaD and delta13C analyses of gas mixtures are useful indicators of geochemical and environmental factors. However, the relative concentrations of individual components in gas mixtures (e.g., H2, CO2, methane, ethane, propane, i-butane, n-butane) may vary over several orders of magnitude. The determination of hydrogen and carbon compound-specific stable isotope ratios requires that the hydrogen and carbon dioxide produced from each separated component has a concentration adjusted to match the dynamic range of the stable isotope mass spectrometer. We present a custom-built gas sampling and injection system (GASIS) linked with a Delta Plus XP mass spectrometer that provides flexibility, ease of operation, and economical use of small gas samples with wide ranges of analyte concentrations. The overall on-line GC-ox/red-IRMS (Gas Chromatography - oxidation/reduction - Isotope Ratio Mass Spectrometry) system consists of (i) a customized GASIS inlet system and (ii) two alternative reactors, namely an oxidative Cu-Ni-Pt reactor at 950 degrees C for production of CO2 and a reductive graphitized Al2O3 reactor at 1420 degrees C for production of H2. In addition, the system is equipped with (iii) a liquid nitrogen spray-cooling unit for cryo-GC-focusing at -20 degrees C, and (iv) a Nafion dryer for removal of water vapor from product CO2. The three injection loops of the GASIS inlet allow flexibility in the volume of injected analyte gas (e.g., from 0.06 to 500 microL) in order to measure reproducible deltaD and delta13C values for gases at concentrations ranging from 100% down to 10 ppm. We calibrate our GC-ox/red-IRMS system with two isotopically distinct methane references gases that are combusted off-line and characterized using dual-inlet IRMS. PMID:17577874

Henning, Mark; Strapo?, Dariusz; Lis, Grzegorz P; Sauer, Peter; Fong, Jon; Schimmelmann, Arndt; Pratt, Lisa M

2007-01-01

303

Frugality ratios and improved truthful mechanisms for vertex cover  

Microsoft Academic Search

In set-system auctions, there are several overlapping teams of agents, and a task that can be completed by any of these teams. The buyer's goal is to hire a team and pay as little as possible. Recently, Karlin, Kempe and Tamir introduced a new definition of frugality ratio for this setting. Informally, the frugality ratio is the ratio of the

Edith Elkind; Leslie Ann Goldberg; Paul W. Goldberg

2007-01-01

304

Spatial and temporal infaunal dynamics of the Blanes submarine canyon-slope system (NW Mediterranean); changes in nematode standing stocks, feeding types and gender-life stage ratios  

NASA Astrophysics Data System (ADS)

Despite recent advances in the knowledge of submarine canyons ecosystems, our understanding of the faunal patterns and processes in these environments is still marginal. In this study, meiobenthic nematode communities (from 300 m to 1600 m depth) obtained in November 2003 and May 2004 at eight stations inside and outside Blanes submarine canyon were analysed for nematode standing stocks (SSs), feeding types and gender-life stage distributions. Environmental data were obtained by sediment traps and current meters, attached to moorings (April 2003-May 2004), and sediments samples analysed for biogeochemistry and grain size (May 2004). In November 2003, nematode SSs decreased with increasing depth (367.2 individuals and 7.31 ?g C per 10 cm2 at 388 m water depth to 7.7 individuals and 0.18 ?g C per 10 cm2 at 1677 m water depth), showing a significant negative relation (abundance: R2 = 0.620, p = 0.020; biomass: R2 = 0.512, p = 0.046). This was not the case in May 2004 (283.5 individuals and 3.53 ?g C per 10 cm2 at 388 m water depth to 490.8 individuals and 4.93 ?g C per 10 cm2 at 1677 m water depth; abundance: R2 = 0.003, p = 0.902; biomass: R2 = 0.052, p = 0.587), suggesting a temporal effect that overrides the traditional decrease of SSs with increasing water depth. Both water depth and sampling time played a significant role in explaining nematode SSs, but with differences between stations. No overall differences were observed between canyon and open slope stations. Nematode standing stock (SS) patterns can be explained by taking into account the interplay of phytodetrital input and disturbance events, with station differences such as topography playing an important role. Individual nematode size decreased from November 2003 to May 2004 and was explained by a food-induced genera shift and/or a food-induced transition from a ‘latent’ to a ‘reproductive’ nematode community. Our results suggest that size patterns in nematode communities are not solely governed by trophic conditions over longer periods of time in relatively food-rich environments such as canyons. We hypothesize that food pulses in a dynamic and topographical heterogeneous environment such as canyons regulate nematode size distributions, rather than long-term food availability. Feeding type distributions in the Blanes Canyon did not clearly resemble those from other canyon systems, apart from the spring assemblage at one station in the head of the canyon.

Ingels, Jeroen; Vanreusel, Ann; Romano, Chiara; Coenjaerts, Johan; Mar Flexas, M.; Zúñiga, Diana; Martin, Daniel

2013-11-01

305

Lidar ratio and depolarization ratio for cirrus clouds.  

PubMed

We report on studies of the lidar and the depolarization ratios for cirrus clouds. The optical depth and effective lidar ratio are derived from the transmission of clouds, which is determined by comparing the backscattering signals at the cloud base and cloud top. The lidar signals were fitted to a background atmospheric density profile outside the cloud region to warrant the linear response of the return signals with the scattering media. An average lidar ratio, 29 +/- 12 sr, has been found for all clouds measured in 1999 and 2000. The height and temperature dependences ofthe lidar ratio, the optical depth, and the depolarization ratio were investigated and compared with results of LITE and PROBE. Cirrus clouds detected near the tropopause are usually optically thin and mostly subvisual. Clouds with the largest optical depths were found near 12 km with a temperature of approximately -55 degrees C. The multiple-scattering effect is considered for clouds with high optical depths, and this effect lowers the lidar ratios compared with a single-scattering condition. Lidar ratios are in the 20-40 range for clouds at heights of 12.5-15 km and are smaller than approximately 30 in height above 15 km. Clouds are usually optically thin for temperatures below approximately -65 degrees C, and in this region the optical depth tends to decrease with height. The depolarization ratio is found to increase with a height at 11-15 km and smaller than 0.3 above 16 km. The variation in the depolarization ratio with the lidar ratio was also reported. The lidar and depolarization ratios were discussed in terms of the types of hexagonal ice crystals. PMID:12396200

Chen, Wei-Nai; Chiang, Chih-Wei; Nee, Jan-Bai

2002-10-20

306

Negative Poisson's ratio polyethylene foams  

Microsoft Academic Search

Various polyethylene foams were subjected to thermo-mechanical processing with the aim of transforming them into re-entrant materials exhibiting negative Poisson's ratio. Following transformation, large cell foams (cell sizes of 1 and 2 mm) exhibited re-entrant cell structure and negative Poisson's ratio over a range of processing times and temperatures. Poisson's ratio vs. strain for these foams was similar to prior

B. Brandel; R. S. Lakes

2001-01-01

307

Sex ratio dependent dispersal when sex ratios vary between patches  

Microsoft Academic Search

Female biased sex ratios reduce competition between brothers when mating takes place within local patches. Male dispersal prior to mating is another strategy that reduces competition between brothers. One may thus expect these two traits to co-evolve and this is partially met in that sex ratios becomes less female biased as dispersal increases. However, the evolutionary stable degree of dispersal

Ronald M. Nelson; Jaco M. Greeff

2011-01-01

308

Air/fuel ratio controller  

SciTech Connect

An internal combustion engine has a fuel injection pump and an air/fuel ratio controller. The controller has a lever that is connected to the pump lever. An aneroid moves the controller lever as a function of changes in intake manifold vacuum to maintain a constant air/fuel ratio to the mixture charge. A fuel enrichment linkage is provided that modifies the movement of the fuel flow control lever by the aneroid in response to changes in manifold gas temperature levels and exhaust gas recirculation to maintain the constant air/fuel ratio. A manual override is provided to obtain a richer air/fuel ratio for maximum acceleration.

Schechter, M.M.; Simko, A.O.

1980-12-23

309

Calculating Confidence Intervals for Rates and Ratios  

Microsoft Academic Search

Since the probability of developing or dying from most neurologic disorders is relatively small, the Poisson distribution is often utilized to establish confidence intervals around rates or ratios for diseases of the nervous system. This report describes a simplified method and provides a table of factors based on the Poisson distribution for calculating confidence intervals around estimates of rates and

Bruce S. Schoenberg

1983-01-01

310

NERO-The Neutron Emission Ratio Observer  

NASA Astrophysics Data System (ADS)

The Neutron Emission Ratio Observer (NERO), has been constructed for the use at the National Superconducting Cyclotron Laboratory to work in conjunction with the NSCL Beta Counting System in order to detect ?-delayed neutrons. The design of the detector provides high and flat efficiency for a wide range of neutron energies, as well as a low neutron background.

Lorusso, Giuseppe; Pereira, Jorque; Hosmer, Paul; Kratz, Karl Ludvig; Montes, Fernando; Reeder, Paul; Santi, Peter; Schatz, Hendrik

2007-10-01

311

Ultraviolet Emission Line Ratios of Cataclysmic Variables  

E-print Network

We present a statistical analysis of the ultraviolet emission lines of cataclysmic variables (CVs) based on $\\approx 430$ ultraviolet spectra of 20 sources extracted from the International Ultraviolet Explorer Uniform Low Dispersion Archive. These spectra are used to measure the emission line fluxes of N V, Si IV, C IV, and He II and to construct diagnostic flux ratio diagrams. We investigate the flux ratio parameter space populated by individual CVs and by various CV subclasses (e.g., AM Her stars, DQ Her stars, dwarf novae, nova-like variables). For most systems, these ratios are clustered within a range of $\\sim 1$ decade for log Si IV/C IV $\\approx -0.5$ and log He II/C IV $\\approx -1.0$ and $\\sim 1.5$ decades for log N V/C IV $\\approx -0.25$. These ratios are compared to photoionization and collisional ionization models to constrain the excitation mechanism and the physical conditions of the line-emitting gas. We find that the collisional models do the poorest job of reproducing the data. The photoionization models reproduce the Si IV/C IV line ratios for some shapes of the ionizing spectrum, but the predicted N V/C IV line ratios are simultaneously too low by typically $\\sim 0.5$ decades. Worse, for no parameters are any of the models able to reproduce the observed He II/C IV line ratios; this ratio is far too small in the collisional and scattering models and too large by typically $\\sim 0.5$ decades in the photoionization models.

Christopher W. Mauche; Y. Paul Lee; Timothy R. Kallman

1996-09-20

312

Progressive Ratio Schedules of Reinforcement  

PubMed Central

Pigeons’ pecks produced grain under progressive ratio (PR) schedules, whose response requirements increased systematically within sessions. Experiment 1 compared arithmetic (AP) and geometric (GP) progressions. Response rates increased as a function of the component ratio requirement, then decreased linearly (AP) or asymptotically (GP). Experiment 2 found the linear decrease in AP rates to be relatively independent of step size. Experiment 3 showed pausing to be controlled by the prior component length, which predicted the differences between PR and regressive ratio schedules found in Experiment 4. When the longest component ratios were signaled by different key colors, rates at moderate ratios increased, demonstrating control by forthcoming context. Models for response rate and pause duration described performance on AP schedules; GP schedules required an additional parameter representing the contextual reinforcement. PMID:19159161

Killeen, Peter R.; Posadas-Sanchez, Diana; Johansen, Espen Borgå; Thrailkill, Eric A.

2009-01-01

313

Pressure Ratio to Thermal Environments  

NASA Technical Reports Server (NTRS)

A pressure ratio to thermal environments (PRatTlE.pl) program is a Perl language code that estimates heating at requested body point locations by scaling the heating at a reference location times a pressure ratio factor. The pressure ratio factor is the ratio of the local pressure at the reference point and the requested point from CFD (computational fluid dynamics) solutions. This innovation provides pressure ratio-based thermal environments in an automated and traceable method. Previously, the pressure ratio methodology was implemented via a Microsoft Excel spreadsheet and macro scripts. PRatTlE is able to calculate heating environments for 150 body points in less than two minutes. PRatTlE is coded in Perl programming language, is command-line-driven, and has been successfully executed on both the HP and Linux platforms. It supports multiple concurrent runs. PRatTlE contains error trapping and input file format verification, which allows clear visibility into the input data structure and intermediate calculations.

Lopez, Pedro; Wang, Winston

2012-01-01

314

Arcjet nozzle area ratio effects  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted to determine the effect of nozzle area ratio on the operating characteristics and performance of a low power dc arcjet thruster. Conical thoriated tungsten nozzle inserts were tested in a modular laboratory arcjet thruster run on hydrogen/nitrogen mixtures simulating the decomposition products of hydrazine. The converging and diverging sides of the inserts had half angles of 30 and 20 degrees, respectively, similar to a flight type unit currently under development. The length of the diverging side was varied to change the area ratio. The nozzle inserts were run over a wide range of specific power. Current, voltage, mass flow rate, and thrust were monitored to provide accurate comparisons between tests. While small differences in performance were observed between the two nozzle inserts, it was determined that for each nozzle insert, arcjet performance improved with increasing nozzle area ratio to the highest area ratio tested and that the losses become very pronounced for area ratios below 50. These trends are somewhat different than those obtained in previous experimental and analytical studies of low Re number nozzles. It appears that arcjet performance can be enhanced via area ratio optimization.

Curran, Francis M.; Sarmiento, Charles J.; Birkner, Bjorn W.; Kwasny, James

1990-01-01

315

Arcjet Nozzle Area Ratio Effects  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted to determine the effect of nozzle area ratio on the operating characteristics and performance of a low power dc arcjet thruster. Conical thoriated tungsten nozzle inserts were tested in a modular laboratory arcjet thruster run on hydrogen/nitrogen mixtures simulating the decomposition products of hydrazine. The converging and diverging sides of the inserts had half angles of 30 and 20 degrees, respectively, similar to a flight type unit currently under development. The length of the diverging side was varied to change the area ratio. The nozzle inserts were run over a wide range of specific power. Current, voltage, mass flow rate, and thrust were monitored to provide accurate comparisons between tests. While small differences in performance were observed between the two nozzle inserts, it was determined that for each nozzle insert, arcjet performance improved with increasing nozzle area ratio to the highest area ratio tested and that the losses become very pronounced for area ratios below 50. These trends are somewhat different than those obtained in previous experimental and analytical studies of low Re number nozzles. It appears that arcjet performance can be enhanced via area ratio optimization.

Curran, Francis M.; Sarmiento, Charles J.; Birkner, Bjorn W.; Kwasny, James

1990-01-01

316

Low-speed tests of a high-aspect-ratio, supercritical-wing transport model equipped with a high-lift flap system in the Langley 4- by 7-meter and Ames 12-foot pressure tunnels  

NASA Technical Reports Server (NTRS)

The Ames 12-Foot Pressure Tunnel was used to determine the effects of Reynolds number on the static longitudinal aerodynamic characteristics of an advanced, high-aspect-ratio, supercritical wing transport model equipped with a full span, leading edge slat and part span, double slotted, trailing edge flaps. The model had a wing span of 7.5 ft and was tested through a free stream Reynolds number range from 1.3 to 6.0 x 10 to 6th power per foot at a Mach number of 0.20. Prior to the Ames tests, an investigation was also conducted in the Langley 4 by 7 Meter Tunnel at a Reynolds number of 1.3 x 10 to 6th power per foot with the model mounted on an Ames strut support system and on the Langley sting support system to determine strut interference corrections. The data obtained from the Langley tests were also used to compare the aerodynamic charactertistics of the rather stiff, 7.5-ft-span steel wing model tested during this investigation and the larger, and rather flexible, 12-ft-span aluminum-wing model tested during a previous investigation. During the tests in both the Langley and Ames tunnels, the model was tested with six basic wing configurations: (1) cruise; (2) climb (slats only extended); (3) 15 deg take-off flaps; (4) 30 deg take-off flaps; (5) 45 deg landing flaps; and (6) 60 deg landing flaps.

Morgan, H. L., Jr.; Kjelgaard, S. O.

1983-01-01

317

Design of an ultrasmall aspect ratio concentrator  

NASA Astrophysics Data System (ADS)

The concentrated photovoltaic (CPV) can be employed to improve the efficiency of solar cells and reduce the system cost of power generation, which is the primary part of the CPV system. Based on the demands for the concentrators to have an ultrathin and ultralight design, a design of ultrasmall aspect ratio concentrators is proposed. The concentrator is formed by a lens array and a freeform reflector to precisely control the light. The solar cell is placed at the side of the concentrator, which greatly reduces the overall thickness of the concentrator. The design can reduce the aspect ratio of concentrator by a considerable amount. The freeform reflector can shape the light beam and achieve a uniform distribution of light energy.

Cheng, Ying; Fang, Fengzhou; Zhang, Xiaodong

2014-11-01

318

Point Estimation: Odds Ratios, Hazard Ratios, Risk Differences, Precision  

NSDL National Science Digital Library

This site provides a PowerPoint presentation, created by Dr. Elizabeth Garrett-Mayer of Johns Hopkins University, of a lesson and examples of point estimation, odds ratios, hazard ratios, risk differences and precision. The presentations is quite thorough. The author attempts to define, provide examples of, and then show the application of almost every concept. The presentation follows a easily followed and logical order. Mathematical formulas are intertwined within the slides. If further research is necessary, the author has provided a list of references and cites them during the presentation.

Garrett-Mayer, Elizabeth

319

Fuel equivalence ratio imaging for methane jets  

Microsoft Academic Search

A 2-D fuel\\/oxygen equivalence ratio imaging system has been developed. The technique exploits the efficient quenching of the fluorescence of organic molecules by molecular oxygen in order to determine the fuel and oxygen partial pressures simultaneously. Following pulsed planar laser excitation of fluoranthene-a specially selected fluorescent dopant-two images of the fluorescence were recorded, with the second image being delayed by

T. Q. Ni; L. A. Melton

1993-01-01

320

Particle ratios at SPS, AGS and SIS  

E-print Network

Ratios of integrated particle yields provide the best method for determining the temperature and the chemical potential. The chemical freeze-out parameters obtained at CERN/SPS, BNL/AGS and GSI/SIS energies all correspond to a unique value of 1 GeV per hadron in the local rest frame of the system, independent of the beam energy and of the target and beam particles.

J. Cleymans; H. Oeschler; K. Redlich

1998-09-10

321

Discovering Phi: The Golden Ratio  

NSDL National Science Digital Library

Students discover the mathematical constant phi, the golden ratio, through hands-on activities. They measure dimensions of "natural objects"—a star, a nautilus shell and human hand bones—and calculate ratios of the measured values, which are close to phi. Then students learn a basic definition of a mathematical sequence, specifically the Fibonacci sequence. By taking ratios of successive terms of the sequence, they find numbers close to phi. They solve a squares puzzle that creates an approximate Fibonacci spiral. Finally, the instructor demonstrates the rule of the Fibonacci sequence via a LEGO® MINDSTORMS® NXT robot equipped with a pen. The robot (already created as part of the companion activity, The Fibonacci Sequence & Robots) draws a Fibonacci spiral that is similar to the nautilus shape.

AMPS GK-12 Program,

322

Surface to Volume Ratio Activity  

NSDL National Science Digital Library

By the National Nanotechnology Infrastructure Network, this two-part laboratory activity was designed to complement any chemistry unit on catalysts to "help students understand how nanoparticles may be more effective catalysts by investigating how the surface area-to-volume ratio of a substance is affected as its shape changes." On this site, educators can find both the teacher and student instructions for preparing and presenting the laboratory with objectives, time periods, materials, procedures, example answers, and much more. It is a ready-to-use lesson to help students understand catalysts and surface to volume ratio at molecular and atomic levels.

323

Energy Balance Bowen Ratio Station (EBBR) Handbook  

SciTech Connect

The energy balance Bowen ratio (EBBR) system produces 30-minute estimates of the vertical fluxes of sensible and latent heat at the local surface. Flux estimates are calculated from observations of net radiation, soil surface heat flux, and the vertical gradients of temperature and relative humidity (RH). Meteorological data collected by the EBBR are used to calculate bulk aerodynamic fluxes, which are used in the Bulk Aerodynamic Technique (BA) EBBR value-added product (VAP) to replace sunrise and sunset spikes in the flux data. A unique aspect of the system is the automatic exchange mechanism (AEM), which helps to reduce errors from instrument offset drift.

Cook, DR

2011-02-23

324

In-line process control for laser welding of titanium by high dynamic range ratio pyrometry and plasma spectroscopy  

NASA Astrophysics Data System (ADS)

The production of complex titanium components for various industries using laser welding processes has received growing attention in recent years. It is important to know whether the result of the cohesive joint meets the quality requirements of standardization and ultimately the customer requirements. Erroneous weld seams can have fatal consequences especially in the field of car manufacturing and medicine technology. To meet these requirements, a real-time process control system has been developed which determines the welding quality through a locally resolved temperature profile. By analyzing the resulting weld plasma received data is used to verify the stability of the laser welding process. The determination of the temperature profile is done by the detection of the emitted electromagnetic radiation from the material in a range of 500 nm to 1100 nm. As detectors, special high dynamic range CMOS cameras are used. As the emissivity of titanium depends on the wavelength, the surface and the angle of radiation, measuring the temperature is a problem. To solve these a special pyrometer setting with two cameras is used. That enables the compensation of these effects by calculating the difference between the respective pixels on simultaneously recorded images. Two spectral regions with the same emissivity are detected. Therefore the degree of emission and surface effects are compensated and canceled out of the calculation. Using the spatially resolved temperature distribution the weld geometry can be determined and the laser process can be controlled. The active readjustment of parameters such as laser power, feed rate and inert gas injection increases the quality of the welding process and decreases the number of defective goods.

Lempe, B.; Taudt, C.; Baselt, T.; Rudek, F.; Maschke, R.; Basan, F.; Hartmann, P.

2014-02-01

325

Isotope ratios in photosynthetic oxygen.  

PubMed

Axenic suspensions of the fresh water green alga Ankistrodesmus braunii were illuminated under aerobic conditions. The released gas mixture was introduced into the ion source of an isotope mass spectrometer, which recorded the 18O/16O ratio. The 18O content of the photosynthetic oxygen (approximately 0.199%) exceeded that of the cell water (approximately 0.197%) significantly. PMID:508731

Metzner, H; Fischer, K; Bazlen, O

1979-11-01

326

A Ratio Explanation for Evolution.  

ERIC Educational Resources Information Center

Describes hands-on physical anthropology activities for teaching students about evolution. Using evidence found in hominid skulls, students conduct investigations that involve calculating ratios. Eight full-page photographs of skulls from the program Stones and Bones are included. (PR)

Riss, Pam Helfers

1993-01-01

327

Empirical Likelihood Ratio Confidence Regions  

Microsoft Academic Search

An empirical likelihood ratio function is defined and used to obtain confidence regions for vector valued statistical functionals. The result is a nonparametric version of Wilks' theorem and a multivariate generalization of work by Owen. Cornish-Fisher expansions show that the empirical likelihood intervals for a one dimensional mean are less adversely affected by skewness than are those based on Student's

Art Owen

1990-01-01

328

Laminar premixed flame response to equivalence ratio oscillations  

Microsoft Academic Search

Self-excited oscillations in low emission, premixed combustion systems are often caused by feedback between unsteady heat release rates and reactive mixture equivalence ratio perturbations. This paper presents an analysis of the flame response to equivalence ratio perturbations, showing that the heat release response is controlled by the superposition of three disturbances: heat of reaction, flame speed, and flame area. The

Ju Hyeong Cho; Tim Lieuwen

2005-01-01

329

Thread motion ratio used to monitor sewing machines  

Microsoft Academic Search

A prototype system for detecting sewing defects through analysis of thread motion has been developed. A piezo-electric transducer provides information on the time of motion of the top thread in a lockstitch sewing process. The ratio of this time of motion to the total single sewing cycle time is a measure termed the thread motion ratio. This measure offers consistency

J. Lewis Dorrity; L. Howard Olson

1996-01-01

330

Prevalence odds ratio or prevalence ratio in the analysis of cross sectional data: what is to be done?  

Microsoft Academic Search

OBJECTIVES: To review the appropriateness of the prevalence odds ratio (POR) and the prevalence ratio (PR) as effect measures in the analysis of cross sectional data and to evaluate different models for the multivariate estimation of the PR. METHODS: A system of linear differential equations corresponding to a dynamic model of a cohort with a chronic disease was developed. At

M. L. Thompson; J. E. Myers; D. Kriebel

1998-01-01

331

Optomechanical Raman-Ratio Thermometry  

E-print Network

The temperature dependence of the asymmetry between Stokes and anti-Stokes Raman scattering can be exploited for self-calibrating, optically-based thermometry. In the context of cavity optomechanics, we observe the cavity-enhanced scattering of light interacting with the standing-wave drumhead modes of a silicon nitride membrane mechanical resonator. The ratio of the amplitude of Stokes to anti-Stokes scattered light is used to measure temperatures of optically-cooled mechanical modes down to the level of a few vibrational quanta. We demonstrate that the Raman-ratio technique is able to measure the physical temperature of our device over a range extending from cryogenic temperatures to within an order of magnitude of room temperature.

T. P. Purdy; P. -L. Yu; N. S. Kampel; R. W. Peterson; K. Cicak; R. W. Simmonds; C. A. Regal

2014-06-27

332

Optomechanical Raman-Ratio Thermometry  

E-print Network

The temperature dependence of the asymmetry between Stokes and anti-Stokes Raman scattering can be exploited for self-calibrating, optically-based thermometry. In the context of cavity optomechanics, we observe the cavity-enhanced scattering of light interacting with the standing-wave drumhead modes of a silicon nitride membrane mechanical resonator. The ratio of the amplitude of Stokes to anti-Stokes scattered light is used to measure temperatures of optically-cooled mechanical modes down to the level of a few vibrational quanta. We demonstrate that the Raman-ratio technique is able to measure the physical temperature of our device over a range extending from cryogenic temperatures to within an order of magnitude of room temperature.

Purdy, T P; Kampel, N S; Peterson, R W; Cicak, K; Simmonds, R W; Regal, C A

2014-01-01

333

Rates, Ratios, Percents, and Proportions  

NSDL National Science Digital Library

Each of these sites will help you get better with percentages, rates, ratios, and solving proportions by cross-multiplying. 1. Begin by comparing fractions to decimals and to percentages. These two sites are similar. Pick one and practice it for a few minutes. Fraction-Decimal-Percent Chart or Percents-Fractions-Decimals (2) 2. Next, try to solve these percentage word problems. To find the problems, scroll down to the bottom of the page to the "Exercises." ...

hbinggeli

2010-10-22

334

Sex ratios in bumble bees  

PubMed Central

The median proportion of investment in females among 11 populations of seven bumble bee (Bombus) species was 0.32 (range 0.07 to 0.64). By contrast, two species of workerless social parasites in the related genus Psithyrus had female-biased sex allocation, the reasons for which remain unclear. Male-biased sex allocation in Bombus contradicts the predictions of Trivers and Hare's sex ratio model for the social Hymenoptera, which are that the population sex investment ratio should be 0.5 (1:1) under queen control and 0.75 (3:1 females:males) under worker control (assuming single, once-mated, outbred queens and non-reproductive workers). Male bias in Bombus does not appear to be either an artefact, or purely the result of symbiotic sex ratio distorters. According to modifications of the Trivers–Hare model, the level of worker male-production in Bombus is insufficient to account for observed levels of male bias. There is also no evidence that male bias arises from either local resource competition (related females compete for resources) or local mate enhancement (related males cooperate in securing mates). Bulmer presented models predicting sexual selection for protandry (males are produced before females) in annual social Hymenoptera and, as a consequence (given some parameter values), male-biased sex allocation. Bumble bees fit the assumptions of Bulmer's models and are protandrous. These models therefore represent the best current explanation for the bees' male-biased sex investment ratios. This conclusion suggests that the relative timing of the production of the sexes strongly influences sex allocation in the social Hymenoptera.

Bourke, A. F. G.

1997-01-01

335

Measurement of Tau branching ratios  

Microsoft Academic Search

Using the data accumulated at LEP in 1989 and 1990 with the ALEPH detector, the inclusive and exclusive branching ratios of the t lepton have been measured assuming lepton universality inZ0 decays. The inclusive branching fractions for the t decay into one, three, and five charged particles have been determined to be (85.45±0.97)%, (14.35±0.48)%, and (0.10±0.05)%, respectively, in agreement with

D. Decamp; B. Deschizeaux; C. Goy; J.-P. Lees; M.-N. Minard; R. Alemany; J. M. Crespo; M C Delfino; E. Fernandez; V. Gaitan; Ll. Garrido; Ll. M. Mir; A. Pacheco; M. G. Catanesi; D. Creanza; M. de Palma; A. Farilla; Giuseppe Iaselli; G. Maggi; M. Maggi; S. Natali; S. Nuzzo; M. Quattromini; A. Ranieri; G. Raso; F. Romano; F. Ruggieri; G. Selvaggi; L. Silvestris; P. Tempesta; G. Zito; H. Hu; D. Huang; X. Huang; J. Lin; J. Lou; C. Qiao; T. Ruan; T. Wang; Y. Xie; D. Xu; R. Xu; J. Zhang; W. Zhao; W. B. Atwood; L. A. T. Bauerdick; F. Bird; E. Blucher; G. Bonvicini; F. Bossi; J. Boudreau; T. H. Burnett; H. Drevermann; R. W. Forty; C. Grab; R. Hagelberg; S. Haywood; J. Hilgart; B. Jost; M. Kasemann; J. Knobloch; A. Lacourt; E. Lançon; I. Lehraus; T. Lohse; A. Lusiani; A. Marchioro; M. Martinez; P. Mato; S. Menary; T. Meyer; A. Minten; A. Miotto; R. Miquel; H.-G. Moser; J. Nash; P. Palazzi; F. Ranjard; G. Redlinger; L. Rolandi; A E Roth; J E Rothberg; M. Saich; D. Schlatter; M. Schmelling; W. Tejessy; H. Wachsmuth; S. Wasserbaech; W. Wiedenmann; W. Witzeling; J. Wotschack; Z. Ajaltouni; F. Badaud; M. Bardadin-Otwinowska; A. M. Bencheikh; R. El Fellous; A. Falvard; P. Gay; C. Guicheney; P. Henrard; J. Jousset; B. Michel; J.-C. Montret; D. Pallin; P. Perret; B. Pietrzyk; J. Proriol; F. Prulhière; G. Stimpfl; J. D. Hansen; J. R. Hansen; P. H. Hansen; R. Møllerud; B. S. Nilsson; I. Efthymiopoulos; E. Simopoulos; A. Vayaki; J. Badier; A. Blondel; G. Bonneaud; J. C. Brient; G. Fouque; A. Gamess; J. Harvey; S. Orteu; A. Rosowsky; A. Rougé; M. Rumpf; R. Tanaka; H. Videau; D. J. Candlin; E. Veitch; L. Moneta; G. Parrini; M. Corden; C. Georgiopoulos; M. Ikeda; J. Lannutti; D. Levinthal; M. Mermikides; L. Sawyer; A. Antonelli; R. Baldini; G. Bencivenni; G. Bologna; P. Campana; G. Capon; F. Cerutti; V. Chiarella; B. D'Ettore-Piazzoli; G. Felici; P. Laurelli; G. Mannocchi; F. Murtas; G. P. Murtas; L. Passalacqua; M. Pepe-Altarelli; P. Picchi; P. Zografou; B. Altoon; O. Boyle; P. Colrain; A. W. Halley; I. ten Have; J. G. Lynch; W. Maitland; W. T. Morton; C. Raine; J. M. Scarr; K. Smith; A. S. Thompson; R. M. Turnbull; B. Brandl; O. Braun; R. Geiges; C. Geweniger; P. Hanke; V. Hepp; E. E. Kluge; Y. Maumary; A. Putzer; B. Rensch; A. Stahl; K. Tittel; M. Wunsch; A. T. Belk; R. Beuselinck; D. M. Binnie; W. Cameron; M. Cattaneo; P. J. Dornan; S. Dugeay; A. M. Greene; J. F. Hassard; N. M. Lieske; S. J. Patton; D. G. Payne; M. J. Phillips; J. K. Sedgbeer; G. Taylor; I. R. Tomalin; A. G. Wright; P. Girtler; D. Kuhn; G. Rudolph; C. K. Bowdery; T. J. Broodbeck; A. J. Finch; F. Foster; G. Hughes; D. Jackson; N. R. Keemer; M. Nuttall; A. Patel; T. Sloan; S. W. Snow; E. P. Whelan; T. Barczewski; K. Kleinknecht; J. Raab; B. Renk; S. Roehn; H.-G. Sander; H. Schmidt; F. Steeg; S. M. Walther; B. Wolf; J.-J. Aubert; C. Benchouk; V. Bernard; A. Bonissent; J. Carr; P. Coyle; J. Drinkhard; F. Etienne; S. Papalexiou; P. Payre; Z. Qian; D. Rousseau; P. Schwemling; M. Talby; S. Adlung; H. Becker; W. Blum; D. Brown; P. Cattaneo; G. Cowan; B. Dehning; H. Dietl; F. Dydak; M. Fernandez-Bosman; T. Hansl-Kosanecka; A. Jahn; W. Kozanecki; E. Lange; J. Lauber; G. Lütjens; G. Lutz; W. Männer; R. Richter; H. Rotscheidt; J. Schröder; A. S. Schwarz; R. Settles; U. Stierlin; U. Stiegler; R. St. Denis; M. Takashima; J. Thomas; G. Wolf; V. Bertin; J. Boucrot; O. Callot; X. Chen; A. Cordier; M. Davier; J.-F. Grivaz; Ph. Heusse; P. Janot; D. W. Kim; F. Le Diberder; J. Lefrançois; A.-M. Lutz; M.-H. Schune; J.-J. Veillet; I. Videau; Z. Zhang; F. Zomer; D. Abbaneo; S. R. Amendolia; G. Bagliesi; G. Batignani; L. Bosisio; U. Bottigli; C. Bradaschia; M. Carpinelli; R. Dell'Orso; I. Ferrante; F. Fidecaro; L. Foà; E. Focardi; F. Forti; C. Gatto; A. Grassi; M. A. Giorgi; F. Ligabue; E. B. Mannelli; P. S. Marrocchesi; A. Messineo; F. Palla; G. Sanguinetti; J. Steinberger; R. Tenchini; G. Tonelli; G. Triggiani; C. Vannini; A. Venturi; P. G. Verdini; J. Walsh; J. M. Carter; M. G. Green; P. V. March; T. Medcalf; I. S. Quasi; J. A. Strong; L. R. West; T. Wildish; D. R. Botterill; R. W. Clifft; T. R. Edgecock; M. Edwards; S. M. Fisher; T. J. Jones; P. R. Norton; D. P. Salmon; J. C. Thompson; B. Bloch-Devaux; P. Colas; E. Locci; S. Loucatos; E. Monnier; P. Perez; J. A. Perlas; F. Perrier; J. Rander; J.-F. Renardy; A. Roussarie; J.-P. Schuller; J. Schwindling; B. Vallage; J. G. Ashman; C. N. Booth; C. Buttar; R. E. Carney; S. Cartwright; F. Combley; M. Dogru; F. Hatfield; J. Martin; D. Parker; P. Reeves; L. F. Thompson; E. Barberio; S. Brandt; C. Grupen; H. Meinhard; L. Mirabito; U. Schäfer; H. Seywerd; G. Ganis; G. Giannini; B. Gobbo; F. Ragusa; L. Bellantoni; D. Cinabro; J. S. Conway; D. F. Cowen; Z. Feng; D. P. S. Ferguson; Y. S. Gao; J. Grahl; J. L. Harton; R. C. Jared; R. P. Johnson; B. W. LeClaire; C. Lishka; Y. B. Pan; J. R. Pater; Y. Saadi

1992-01-01

336

Rational Industrial Water Reuse Ratios  

NASA Astrophysics Data System (ADS)

This work begins by defining rational water use, and then discusses important factors that most strongly influence it. A general model is then developed to enable factories to quantify the ratio of rational industrial water reuse based on the least cost method. The model is established to minimize the cost of water with reference to gross water use and three subsystems - the intake, reuse, and discharge of industrial water. Discharge cost is determined using data from a 1997 survey of 38 factories, and reuse costs are ranked and expressed by a step function. The model is verified using data from a typical semiconductor factory in northern Taiwan's Hsinchu Science Based Industrial Park, whose effective rational water reuse ratio is about 38 percent. A sensitivity analysis shows that improving water reuse technology is the most important factor in determining the rational water reuse ratio, and the price of water is the second most important. When water costs over NT30 (New Taiwan Dollar, US1 = NT$34) per cubic meter, increasing reuse becomes significant. The model provides a step towards the scientific management of industrial water.

Liaw, Chao-Hsien; Chen, Liang-Ching

2004-08-01

337

Lead-cooled flexible conversion ratio fast reactor  

Microsoft Academic Search

Lead-cooled reactor systems capable of accepting either zero or unity conversion ratio cores depending on the need to burn actinides or operate in a sustained cycle are presented. This flexible conversion ratio reactor is a pool-type 2400MWt reactor coupled to four 600MWt supercritical CO2 (S-CO2) power conversion system (PCS) trains through intermediate heat exchangers. The cores which achieve a power

Anna Nikiforova; Pavel Hejzlar; Neil E. Todreas

2009-01-01

338

Envera Variable Compression Ratio Engine  

SciTech Connect

Aggressive engine downsizing, variable compression ratio and use of the Atkinson cycle are being combined to improve fuel economy by up to 40 percent relative to port fuel injected gasoline engines, while maintaining full engine power. Approach Engine downsizing is viewed by US and foreign automobile manufacturers as one of the best options for improving fuel economy. While this strategy has already demonstrated a degree of success, downsizing and fuel economy gains are currently limited. With new variable compression ratio technology however, the degree of engine downsizing and fuel economy improvement can be greatly increased. A small variable compression ratio (VCR) engine has the potential to return significantly higher vehicle fuel economy while also providing high power. Affordability and potential for near term commercialization are key attributes of the Envera VCR engine. VCR Technology To meet torque and power requirements, a smaller engine needs to do more work per stroke. This is typically accomplished by boosting the incoming charge with either a turbo or supercharger so that more energy is present in the cylinder per stroke to do the work. With current production engines the degree of engine boosting (which correlates to downsizing) is limited by detonation (combustion knock) at high boost levels. Additionally, the turbo or supercharger needs to be responsive and efficient while providing the needed boost. VCR technology eliminates the limitation of engine knock at high load levels by reducing compression ratio to {approx}9:1 (or whatever level is appropriate) when high boost pressures are needed. By reducing the compression ratio during high load demand periods there is increased volume in the cylinder at top dead center (TDC) which allows more charge (or energy) to be present in the cylinder without increasing the peak pressure. Cylinder pressure is thus kept below the level at which the engine would begin to knock. When loads on the engine are low the compression ratio can be raised (to as much as 18:1) providing high engine efficiency. It is important to recognize that for a well designed VCR engine cylinder pressure does not need to be higher than found in current production turbocharged engines. As such, there is no need for a stronger crankcase, bearings and other load bearing parts within the VCR engine. The Envera VCR mechanism uses an eccentric carrier approach to adjust engine compression ratio. The crankshaft main bearings are mounted in this eccentric carrier or 'crankshaft cradle' and pivoting the eccentric carrier 30 degrees adjusts compression ratio from 9:1 to 18:1. The eccentric carrier is made up of a casting that provides rigid support for the main bearings, and removable upper bearing caps. Oil feed to the main bearings transits through the bearing cap fastener sockets. The eccentric carrier design was chosen for its low cost and rigid support of the main bearings. A control shaft and connecting links are used to pivot the eccentric carrier. The control shaft mechanism features compression ratio lock-up at minimum and maximum compression ratio settings. The control shaft method of pivoting the eccentric carrier was selected due to its lock-up capability. The control shaft can be rotated by a hydraulic actuator or an electric motor. The engine shown in Figures 3 and 4 has a hydraulic actuator that was developed under the current program. In-line 4-cylinder engines are significantly less expensive than V engines because an entire cylinder head can be eliminated. The cost savings from eliminating cylinders and an entire cylinder head will notably offset the added cost of the VCR and supercharging. Replacing V6 and V8 engines with in-line VCR 4-cylinder engines will provide high fuel economy at low cost. Numerous enabling technologies exist which have the potential to increase engine efficiency. The greatest efficiency gains are realized when the right combination of advanced and new technologies are packaged together to provide the greatest gains at the least cost. Aggressive engine downsiz

Charles Mendler

2011-03-15

339

Likelihood ratios for genome medicine.  

PubMed

Patients are beginning to present to healthcare providers with the results of high-throughput individualized genotyping, and interpreting these results in the context of the explosive growth of literature linking individual variants with disease may seem daunting. However, we suggest that results of a personal genomic analysis may be viewed as a panel of many tests for multiple diseases. By using well-established methods of evidence based medicine, these very many parallel tests may be combined using likelihood ratios to report a post-test probability of disease for use in patient assessment. PMID:20497613

Morgan, Alexander A; Chen, Rong; Butte, Atul J

2010-01-01

340

Likelihood ratios for genome medicine  

PubMed Central

Patients are beginning to present to healthcare providers with the results of high-throughput individualized genotyping, and interpreting these results in the context of the explosive growth of literature linking individual variants with disease may seem daunting. However, we suggest that results of a personal genomic analysis may be viewed as a panel of many tests for multiple diseases. By using well-established methods of evidence based medicine, these very many parallel tests may be combined using likelihood ratios to report a post-test probability of disease for use in patient assessment. PMID:20497613

2010-01-01

341

Clinical utility of likelihood ratios.  

PubMed

Test-performance characteristics can be derived from a simple 2x2 table displaying the dichotomous relationship between a positive or negative test result and the presence or absence of a target disorder. Sensitivity and specificity, including a summary display of their reciprocal relationship as a receiver operating characteristics curve, are relatively stable test characteristics. Unfortunately, they represent an inversion of customary clinical logic and fail to tell us precisely what we wish to know. Predictive values, on the other hand, provide us with the requisite information but-because they are vulnerable to variation in disease prevalence-are numerically unstable. Likelihood ratios (LRs), in contrast, combine the stability of sensitivity and specificity to provide an omnibus index of test performance far more useful than its constituent parts. Application of Bayes' theorem to LRs produces the following summary equation: Clinically estimated pretest odds of disease x LR=Posttest odds of disease. This simple equation illustrates a concordance between the mathematical properties of likelihood ratios and the central strategy underlying diagnostic testing: the revision of disease probability. PMID:9506499

Gallagher, E J

1998-03-01

342

Isokinetic Hamstrings: Quadriceps Ratios in Intercollegiate Athletes.  

ERIC Educational Resources Information Center

Compared the differences in the concentric hamstrings to quadriceps (H:Q) ratio among athletes in different sports at three velocities. Measurement of H:Q ratio of both knees among male and female college athletes indicated that the H:Q ratio increased as velocity increased. No differences existed for the H:Q ratio for sport or side of body. (SM)

Rosene, John M.; Fogarty, Tracey D.; Mahaffey, Brian L.

2001-01-01

343

Variable ratio regenerative braking device  

DOEpatents

Disclosed is a regenerative braking device (10) for an automotive vehicle. The device includes an energy storage assembly (12) having a plurality of rubber rollers (26, 28) mounted for rotation between an input shaft (36) and an output shaft (42), clutches (38, 46) and brakes (40, 48) associated with each shaft, and a continuously variable transmission (22) connectable to a vehicle drivetrain and to the input and output shafts by the respective clutches. The rubber rollers are torsionally stressed to accumulate energy from the vehicle when the input shaft is clutched to the transmission while the brake on the output shaft is applied, and are torsionally relaxed to deliver energy to the vehicle when the output shaft is clutched to the transmission while the brake on the input shaft is applied. The transmission ratio is varied to control the rate of energy accumulation and delivery for a given rotational speed of the vehicle drivetrain.

Hoppie, Lyle O. (Birmingham, MI)

1981-12-15

344

Beaded Braids: Investigating Patterns & Ratios  

NSDL National Science Digital Library

In this activity learners create patterns of hair beads. Simone and Brianna like different mixes of beads in their braids, so learners must figure out how to distribute 40 beads to satisfy both characters. Images of the two girls are provided in the PDF. Either 20 each of two types of real beads can be used, or the learner can cut out paper beads (20 round and 20 heart-shaped), though the pattern is missing from the PDF. Included questions help learners explore ratio through addition, multiplication, and division. Learners can color the pictures and beads, and make braids with yarn for fun. This activity could also be adapted in terms of decorating lanyard and would connect very well with afterschool or home craft activities.

Lawrence Hall of Science

2003-01-01

345

Advanced high area ratio nozzles  

NASA Technical Reports Server (NTRS)

The objective is to develop computational techniques for the design of high-area-ratio nozzles and to validate these models by comparison with experiments and computations using other codes. Progress was made in two areas during the past year. First, performance computations were added to the PARC2D code and the performance of the SSME nozzle was computed for inviscid, laminar and turbulent flow assuming a perfect gas with gamma = 1.2. Second, the PARC2D code was modified in a non-CASP project to compute equilibrium flow about hypersonic blunt bodies. Progress has been made toward modifying this code to compute equilibrium H2/O2 flow through the SSME and related nozzles.

Raiszadeh, Farhad; Collins, Frank G.; Orr, Joseph L., Jr.; Myruski, Brian

1995-01-01

346

Advanced high area ratio nozzles  

NASA Technical Reports Server (NTRS)

The objective is to develop computational techniques for the design of high-area-ratio nozzles and to validate these models by comparison with experiments and computations using other codes. Performance computations were added to the PARC2D code and the performance of the space shuttle main engine (SSME) nozzle was computed for inviscid, laminar and turbulent flow assuming a perfect gas with gamma = 1.2. The PARC2D code was modified in a non-CASP (Center for Advanced Space Propulsion) project to compute equilibrium flow about hypersonic blunt bodies. Progress has been made toward modifying this code to compute equilibrium H2/O2 flow through the SSME and related nozzles.

Raiszadeh, Farhad; Collins, Frank G.; Orr, Joseph L., Jr.; Myruski, Brian

1989-01-01

347

The C-12/C-13 Ratio as a Chemistry Indicator  

NASA Technical Reports Server (NTRS)

Isotopic ratios of elements are considered powerful tools, e.g. in tracing the origin of solar system body materials, or the degree of nucleosynthesis processing throughout the Galaxy. In interstellar molecules, some isotopic ratios like H/D and C-12/C-13 can also be used as indicators of their chemical origin. Isotope fractionation in gas-phase chemical reactions and gas-dust interaction makes observations of the ratio between C-12 and C-13 isotopologues suitable to distinguish between different formation scenarios. We will present observations of the C-12/C-13 ratio in methanol and formaldehyde towards a sample of embedded, massive young stellar objects. In relation to this we also present results from theoretical modeling showing the usefulness of the C-12/C-13 ratio as a chemistry indicator.

Wirstroem, Eva; Geppert, Wolf; Persson, Carina; Charnley, Steven

2011-01-01

348

Effect of fuel-air-ratio nonuniformity on emissions of nitrogen oxides  

NASA Technical Reports Server (NTRS)

The inlet fuel-air ratio nonuniformity is studied to deterine how nitrogen oxide (NOx) emissions are affected. An increase in NOx emissions with increased fuel-air ratio nonuniformity for average equivalence ratios less than 0.7 and a decrease in NOx emissions for average equivalence ratios near stoichiometric is predicted. The degree of uniformityy of fuel-air ratio profiles that is necessary to achieve NOx emissions goals for actual engines that use lean, premixed, prevaporized combustion systems is determined.

Lyons, V. J.

1981-01-01

349

Temperature Calibration for Optical Pyrometry in Containerless Systems Using Differential Scanning Calorimetry: Application to (-50)  

NASA Astrophysics Data System (ADS)

Accurate and precise measurements of the temperature are important for controlling conditions in any experimental design. In containerless processing, such as in electrostatic levitation and electromagnetic levitation, the temperature is typically measured using optical pyrometers. These are generally calibrated to the sample of interest by measuring the temperatures of phase transitions. The presence of multiple heat signatures, differences in emissivity for different phases, and inconsistencies in published phase diagrams can make this difficult. In this manuscript, a method for using differential scanning calorimetry measurements for calibration is outlined and applied to four Cu-Zr alloys from the eutectic to the line compound. This technique is particularly valuable for systems in which accurate phase diagram information is unavailable or inaccurate.

Bendert, J. C.; Pueblo, C. E.; Veligati, S.; Mauro, N. A.; Kelton, K. F.

2014-10-01

350

High/variable mixture ratio O2/H2 engine  

NASA Technical Reports Server (NTRS)

Vehicle/engine analysis studies have identified the High/Dual Mixture Ratio O2/H2 Engine cycle as a leading candidate for an advanced Single Stage to Orbit (SSTO) propulsion system. This cycle is designed to allow operation at a higher than normal O/F ratio of 12 during liftoff and then transition to a more optimum O/F ratio of 6 at altitude. While operation at high mixture ratios lowers specific impulse, the resultant high propellant bulk density and high power density combine to minimize the influence of atmospheric drag and low altitude gravitational forces. Transition to a lower mixture ratio at altitude then provides improved specific impulse relative to a single mixture ratio engine that must select a mixture ratio that is balanced for both low and high altitude operation. This combination of increased altitude specific impulse and high propellant bulk density more than offsets the compromised low altitude performance and results in an overall mission benefit. Two areas of technical concern relative to the execution of this dual mixture ratio cycle concept are addressed. First, actions required to transition from high to low mixture ratio are examined, including an assessment of the main chamber environment as the main chamber mixture ratio passes through stoichiometric. Secondly, two approaches to meet a requirement for high turbine power at high mixture ratio condition are examined. One approach uses high turbine temperature to produce the power and requires cooled turbines. The other approach incorporates an oxidizer-rich preburner to increase turbine work capability via increased turbine mass flow.

Adams, A.; Parsley, R. C.

1988-01-01

351

Noise of Embedded High Aspect Ratio Nozzles  

NASA Technical Reports Server (NTRS)

A family of high aspect ratio nozzles were designed to provide a parametric database of canonical embedded propulsion concepts. Nozzle throat geometries with aspect ratios of 2:1, 4:1, and 8:1 were chosen, all with convergent nozzle areas. The transition from the typical round duct to the rectangular nozzle was designed very carefully to produce a flow at the nozzle exit that was uniform and free from swirl. Once the basic rectangular nozzles were designed, external features common to embedded propulsion systems were added: extended lower lip (a.k.a. bevel, aft deck), differing sidewalls, and chevrons. For the latter detailed Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) simulations were made to predict the thrust performance and to optimize parameters such as bevel length, and chevron penetration and azimuthal curvature. Seventeen of these nozzles were fabricated at a scale providing a 2.13 inch diameter equivalent area throat." ! The seventeen nozzles were tested for far-field noise and a few data were presented here on the effect of aspect ratio, bevel length, and chevron count and penetration. The sound field of the 2:1 aspect ratio rectangular jet was very nearly axisymmetric, but the 4:1 and 8:1 were not, the noise on their minor axes being louder than the major axes. Adding bevel length increased the noise of these nozzles, especially on their minor axes, both toward the long and short sides of the beveled nozzle. Chevrons were only added to the 2:1 rectangular jet. Adding 4 chevrons per wide side produced some decrease at aft angles, but increased the high frequency noise at right angles to the jet flow. This trend increased with increasing chevron penetration. Doubling the number of chevrons while maintaining their penetration decreased these effects. Empirical models of the parametric effect of these nozzles were constructed and quantify the trends stated above." Because it is the objective of the Supersonics Project that future design work be done more by physics-based computations and less by experiments, several codes under development were evaluated against these test cases. Preliminary results show that the RANS-based code JeNo predicts the spectral directivity of the low aspect ratio jets well, but has no capability to predict the non-axisymmetry. An effort to address this limitations, used in the RANS-based code of Leib and Goldstein, overpredicted the impact of aspect ratio. The broadband shock noise code RISN, also limited to axisymmetric assumptions, did a good job of predicting the spectral directivity of underexpanded 2:1 cold jet case but was not as successful on high aspect ratio jets, particularly when they are hot. All results are preliminary because the underlying CFD has not been validated yet. An effort using a Large Eddy Simulation code by Stanford University predicted noise that agreed with experiments to within a few dB.

Bridges, James E.

2011-01-01

352

A theoretically based determination of bowen-ratio fetch requirements  

USGS Publications Warehouse

Determination of fetch requirements for accurate Bowen-ratio measurements of latent- and sensible-heat fluxes is more involved than for eddy-correlation measurements because Bowen-ratio sensors are located at two heights, rather than just one. A simple solution to the diffusion equation is used to derive an expression for Bowen-ratio fetch requirements, downwind of a step change in surface fluxes. These requirements are then compared to eddy-correlation fetch requirements based on the same diffusion equation solution. When the eddy-correlation and upper Bowen-ratio sensor heights are equal, and the available energy upwind and downwind of the step change is constant, the Bowen-ratio method requires less fetch than does eddy correlation. Differences in fetch requirements between the two methods are greatest over relatively smooth surfaces. Bowen-ratio fetch can be reduced significantly by lowering the lower sensor, as well as the upper sensor. The Bowen-ratio fetch model was tested using data from a field experiment where multiple Bowen-ratio systems were deployed simultaneously at various fetches and heights above a field of bermudagrass. Initial comparisons were poor, but improved greatly when the model was modified (and operated numerically) to account for the large roughness of the upwind cotton field.

Stannard, D.I.

1997-01-01

353

Air-fuel ratio control in spark-ignition engines using estimation theory  

Microsoft Academic Search

Increasingly strict emission standards require very accurate and fast air-fuel (A\\/F) ratio control. Theory, implementation, and experiments for a model-based A\\/F ratio control system using state-space control and estimation methods are presented. An excellent match of the in-cylinder A\\/F ratio with the desired A\\/F ratio can be achieved in spite of the time delay in the system. This is accomplished

Chen-Fang Chang; Nicholas P. Fekete; Alois Amstutz; J. David Powell

1995-01-01

354

Fuel equivalence ratio imaging for methane jets  

SciTech Connect

A 2-D fuel/oxygen equivalence ratio imaging system has been developed. The technique exploits the efficient quenching of the fluorescence of organic molecules by molecular oxygen in order to determine the fuel and oxygen partial pressures simultaneously. Following pulsed planar laser excitation of fluoranthene-a specially selected fluorescent dopant-two images of the fluorescence were recorded, with the second image being delayed by several nanoseconds. Use of a rapid lifetime determination algorithm yielded first a fluorescence lifetime image, and subsequently, with the assumption of Stern-Volmer quenching, an intensity image corrected for quenching. Images of the air pressure, fuel pressure, and the equivalence ratio were obtained. The technique, which uses dual gated intensifiers coupled to a sensitive CCD camera, requires only two integrated fluorescence intensities to calculate the fluorescence lifetime accurately. In the current work, images of the turbulence-induced mixing of a methane jet into quiescent air are displayed. Images can also be obtained in flames, but the analysis of the data is uncertain because the fluorescence lifetime of fluoranthene is temperature dependent. 14 refs., 11 figs.

Ni, T.Q.; Melton, L.A. (Univ. of Texas at Dallas, Richardson (United States))

1993-06-01

355

Implications of Fast Reactor Transuranic Conversion Ratio  

SciTech Connect

Theoretically, the transuranic conversion ratio (CR), i.e. the transuranic production divided by transuranic destruction, in a fast reactor can range from near zero to about 1.9, which is the average neutron yield from Pu239 minus 1. In practice, the possible range will be somewhat less. We have studied the implications of transuranic conversion ratio of 0.0 to 1.7 using the fresh and discharge fuel compositions calculated elsewhere. The corresponding fissile breeding ratio ranges from 0.2 to 1.6. The cases below CR=1 (“burners”) do not have blankets; the cases above CR=1 (“breeders”) have breeding blankets. The burnup was allowed to float while holding the maximum fluence to the cladding constant. We graph the fuel burnup and composition change. As a function of transuranic conversion ratio, we calculate and graph the heat, gamma, and neutron emission of fresh fuel; whether the material is “attractive” for direct weapon use using published criteria; the uranium utilization and rate of consumption of natural uranium; and the long-term radiotoxicity after fuel discharge. For context, other cases and analyses are included, primarily once-through light water reactor (LWR) uranium oxide fuel at 51 MWth-day/kg-iHM burnup (UOX-51). For CR<1, the heat, gamma, and neutron emission increase as material is recycled. The uranium utilization is at or below 1%, just as it is in thermal reactors as both types of reactors require continuing fissile support. For CR>1, heat, gamma, and neutron emission decrease with recycling. The uranium utilization exceeds 1%, especially as all the transuranic elements are recycled. exceeds 1%, especially as all the transuranic elements are recycled. At the system equilibrium, heat and gamma vary by somewhat over an order of magnitude as a function of CR. Isotopes that dominate heat and gamma emission are scattered throughout the actinide chain, so the modest impact of CR is unsurprising. Neutron emitters are preferentially found among the higher actinides, so the neutron emission varies much stronger with CR, about three orders of magnitude.

Steven J. Piet; Edward A. Hoffman; Samuel E. Bays

2010-11-01

356

Variable mixture ratio performance through nitrogen augmentation  

NASA Technical Reports Server (NTRS)

High/variable mixture ratio O2/H2 candidate engine cycles are examined for earth-to-orbit vehicle application. Engine performance and power balance information are presented for the candidate cycles relative to chamber pressure, bulk density, and mixture ratio. Included in the cycle screening are concepts where a third fluid (liquid nitrogen) is used to achieve a variable mixture ratio over the trajectory from liftoff to earth orbit. The third fluid cycles offer a very low risk, fully reusable, low operation cost alternative to high/variable mixture ratio bipropellant cycles. Variable mixture ratio engines with extendible nozzle are slightly lower performing than a single mixture ratio engine (MR = 7:1) with extendible nozzle. Dual expander engines (MR = 7:1) have slightly better performance than the single mixture ratio engine. Dual fuel dual expander engines offer a 16 percent improvement over the single mixture ratio engine.

Beichel, R.; Obrien, C. J.; Bair, E. K.

1988-01-01

357

TRIGONOMETRY: COMPARING RATIO AND UNIT CIRCLE METHODS  

Microsoft Academic Search

Before the 1960s, introductory trigonometry was taught in Victorian schools using the ratio method, where trigonometric functions are defined as ratios of sides of right angled triangles. With the advent of \\

Margaret Kendal; Kaye Stacey

358

Distribution of Grades, Credits Earned Ratios, Course Completion Ratios and Current Grade Point Ratios, University of Hawaii Community Colleges, Fall 1998.  

ERIC Educational Resources Information Center

This document summarizes fall 1998 data on student achievement at the University of Hawaii's seven community colleges along two dimensions: the current grade point ratios earned by students, by program; and the distribution of grades in the courses offered by the colleges. Data are presented for the system and for each individual college. The data…

Hawaii Univ., Honolulu. Office of the Chancellor for Community Colleges.

359

Learning About Ratios: A Sandwich Study  

NSDL National Science Digital Library

This lesson introduces students to the concept of ratio through a hands-on, delicious experiment. After an introductory activity where students identify the ratio of girls to boys in a group of 10 selected students, they create six different peanut butter and jelly sandwiches with different ingredient ratios to find which is the tastiest. Students then plan their own similar experiment using other concoctions which can be expressed in ratios.

Sheryl Weinberg

1999-01-16

360

Transformer ratio improvement for beam based plasma accelerators  

SciTech Connect

Increasing the transformer ratio of wakefield accelerating systems improves the viability of present novel accelerating schemes. The use of asymmetric bunches to improve the transformer ratio of beam based plasma systems has been proposed for some time[1, 2] but suffered from lack appropriate beam creation systems. Recently these impediments have been overcome [3, 4] and the ability now exists to create bunches with current profiles shaped to overcome the symmetric beam limit of R {<=} 2. We present here work towards experiments designed to measure the transformer ratio of such beams, including theoretical models and simulations using VORPAL (a 3D capable PIC code) [5]. Specifically we discuss projects to be carried out in the quasi-nonlinear regime [6] at the UCLA Neptune Laboratory and the Accelerator Test Facility at Brookhaven National Lab.

O'Shea, Brendan; Rosenzweig, James; Barber, Samuel; Fukasawa, Atsushi; Williams, Oliver; Muggli, Patric; Yakimenko, Vitaly; Kusche, Karl [University of California, Los Angeles, Department of Physics and Astronomy, Los Angeles, CA 90095 (United States); University of Southern California, Department of Electrical Engineering, Los Angeles, CA 90089 U.S.A. and Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany); Accelerator Test Facility, Brookhaven National Lab, Upton, NY, 11973 (United States)

2012-12-21

361

REPRODUCTION About sex ratio in pigs  

E-print Network

sex ratio. No clear difference seemed to be linked to the season or the moon stage. The highestII. - REPRODUCTION About sex ratio in pigs J. LOUGNON, M. PICARD ..1,L.C, fSorric /!(!'('/(!/!r;7!Ct?sex ratio at birth were studied

Paris-Sud XI, Université de

362

Spray Gun With Constant Mixing Ratio  

NASA Technical Reports Server (NTRS)

Conceptual mechanism mounted in handle of spray gun maintains constant ratio between volumetric flow rates in two channels leading to spray head. With mechanism, possible to keep flow ratio near 1:1 (or another desired ratio) over range of temperatures, orifice or channel sizes, or clogging conditions.

Simpson, William G.

1987-01-01

363

REPRODUCTION About sex ratio in pigs  

E-print Network

II. - REPRODUCTION About sex ratio in pigs J. LOUGNON, M. PICARD ..1,L.C, fSorric /!(!'('/(!/!r;7!Ct?sex ratio at birth were studied. Combination (4) gave a significantly higher number of males. The lowest sex ratio was registered

Paris-Sud XI, Université de

364

On detecting change in likelihood ratio ordering  

Microsoft Academic Search

This article studies the problem of testing and locating changepoints in likelihood ratios of two multinomial probability vectors. We propose a binary search procedure to detect the changepoints in the sequence of the ratios of probabilities and obtain the maximum likelihood estimators of two multinomial probability vectors under the assumption that the probability ratio sequence has a changepoint. We also

C. Xiong; Hammou El Barmi

2002-01-01

365

Management Ratios 1. For Colleges & Universities.  

ERIC Educational Resources Information Center

Ratios that enable colleges and universities to select other institutions for comparison are presented. The ratios and underlying data also enable colleges to rank order institutions and to calculate means, quartiles, and ranges for these groups. The data are based on FY 1983 U.S. Department of Education Statistics. The ratios summarize the…

Minter, John, Ed.

366

Development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements  

NASA Technical Reports Server (NTRS)

The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation.

Rey, Charles A.

1991-01-01

367

A leading edge heating array and a flat surface heating array: Final design. [for testing the thermal protection system of the space shuttle  

NASA Technical Reports Server (NTRS)

A heating array is described for testing full-scale sections of the leading edge and lower fuselage surfaces of the shuttle. The heating array was designed to provide a tool for development and acceptance testing of leading edge segments and large flat sections of the main body thermal protection system. The array was designed using a variable length module concept to meet test requirements using interchangeable components from one test configuration in another configuration. Heat generating modules and heat absorbing modules were employed to achieve the thermal gradient around the leading edge. A support was developed to hold the modules to form an envelope around a variety of leading edges; to supply coolant to each module; the support structure and to hold the modules in the flat surface heater configuration. An optical pyrometer system mounted within the array was designed to monitor specimen surface temperatures without altering the test article's surface.

1975-01-01

368

Directional spectral emissivity measurement system  

NASA Technical Reports Server (NTRS)

Apparatus and process for determining the emissivity of a test specimen including an integrated sphere having two concentric walls with a coolant circulating therebetween, and disposed within a chamber which may be under ambient, vacuum or inert gas conditions. A reference sample is disposed within the sphere with a monochromatic light source in optical alignment therewith. A pyrometer is in optical alignment with the test sample for obtaining continuous test sample temperature measurements during a test. An arcuate slit port is provided through the spaced concentric walls of the integrating sphere with a movable monochromatic light source extending through and movable along the arcuate slit port. A detector system extends through the integrating sphere for continuously detecting an integrated signal indicative of all radiation within its field of view, as a function of the emissivity of the test specimen at various temperatures and various angle position of the monochromatic light source. A furnace for heating the test sample to approximately 3000 K. and control mechanism for transferring the heated sample from the furnace to the test sample port in the integrating sphere is also contained within the chamber.

Halyo, Nesim (Inventor); Pandey, Dhirendra K. (Inventor)

1992-01-01

369

Neural correlates of the Pythagorean ratio rules.  

PubMed

Millennia ago Pythagoras noted a simple but remarkably powerful rule for the aesthetics of tone combinations: pairs of tones--intervals--with simple ratios such as an octave (ratio 2 : 1) or a fifth (ratio 3 : 2) were pleasant sounding (consonant), whereas intervals with complex ratios such as the major seventh (ratio 243 : 128) were harsh (dissonant). These Pythagorean ratio rules are the building blocks of Western classical music; however, their neurophysiologic basis is not known. Using functional MRI we have found the neurophysiologic correlates of the ratio rules. In musicians, the inferior frontal gyrus, superior temporal gyrus, medial frontal gyrus, inferior parietal lobule and anterior cingulate respond with progressively more activation to perfect consonances, imperfect consonances and dissonances. In nonmusicians only the right inferior frontal gyrus follows this pattern. PMID:17885594

Foss, Alexander H; Altschuler, Eric L; James, Karin H

2007-10-01

370

In this study, five short tubes, with length-to-diametcr (L/D) ratios from 7.5 to 11.9, were tested on a heat pump system with R-22 as the fluid. While the test results for the subcooled liquid have the same general flow  

E-print Network

the entrance of the tube is nearly equal to the saturation pressure of the water. Based on his test results#12;In this study, five short tubes, with length-to-diametcr (L/D) ratios from 7.5 to 11.9, were tested on a heat pump system with R-22 as the fluid. While the test results for the subcooled liquid have

Oak Ridge National Laboratory

371

The Elastic Ratio: Introducing Curvature into Ratio-based Globally Optimal Image Segmentation  

E-print Network

1 The Elastic Ratio: Introducing Curvature into Ratio-based Globally Optimal Image Segmentation globally optimal ratio-based image segmentation method allowing to impose cur- vature regularity such approaches. To identify the optimal foreground region in the image, the algorithm minimizes the ratio of flux

Paris-Sud XI, Université de

372

Ecological genetics of sex ratios in plant populations  

PubMed Central

In many angiosperm species, populations are reproductively subdivided into distinct sexual morphs including females, males and hermaphrodites. Sexual polymorphism is maintained by frequency-dependent selection, leading to predictable sex ratios at equilibrium. Charles Darwin devoted much of his book ‘The Different Forms of Flowers on Plants of the Same Species’ (1877) to investigating plant sexual polymorphisms and laid the foundation for many problems addressed today by integrating theory with empirical studies of the demography and genetics of populations. Here, we summarize our recent work on the ecological and genetic mechanisms influencing variation in sex ratios and their implications for evolutionary transitions among sexual systems. We present the results of a survey of sex ratios from 126 species from 47 angiosperm families and then address two general problems using examples from diverse angiosperm taxa: (i) the mechanisms governing biased sex ratios in dioecious species; (ii) the origins and maintenance of populations composed of females, males and hermaphrodites. Several themes are emphasized, including the importance of non-equilibrium conditions, the role of life history and demography in affecting sex ratios, the value of theory for modelling the dynamics of sex ratio variation, and the utility of genetic markers for investigating evolutionary processes in sexually polymorphic plant populations. PMID:20643745

Barrett, Spencer C. H.; Yakimowski, Sarah B.; Field, David L.; Pickup, Melinda

2010-01-01

373

Ecological genetics of sex ratios in plant populations.  

PubMed

In many angiosperm species, populations are reproductively subdivided into distinct sexual morphs including females, males and hermaphrodites. Sexual polymorphism is maintained by frequency-dependent selection, leading to predictable sex ratios at equilibrium. Charles Darwin devoted much of his book 'The Different Forms of Flowers on Plants of the Same Species' (1877) to investigating plant sexual polymorphisms and laid the foundation for many problems addressed today by integrating theory with empirical studies of the demography and genetics of populations. Here, we summarize our recent work on the ecological and genetic mechanisms influencing variation in sex ratios and their implications for evolutionary transitions among sexual systems. We present the results of a survey of sex ratios from 126 species from 47 angiosperm families and then address two general problems using examples from diverse angiosperm taxa: (i) the mechanisms governing biased sex ratios in dioecious species; (ii) the origins and maintenance of populations composed of females, males and hermaphrodites. Several themes are emphasized, including the importance of non-equilibrium conditions, the role of life history and demography in affecting sex ratios, the value of theory for modelling the dynamics of sex ratio variation, and the utility of genetic markers for investigating evolutionary processes in sexually polymorphic plant populations. PMID:20643745

Barrett, Spencer C H; Yakimowski, Sarah B; Field, David L; Pickup, Melinda

2010-08-27

374

Should sex-ratio distorting parasites abandon horizontal transmission?  

PubMed Central

Background Sex-ratio distorting parasites are of interest due to their effects upon host population dynamics and their potential to influence the evolution of host sex determination systems. In theory, the ability to distort host sex-ratios allows a parasite with efficient vertical (hereditary) transmission to dispense completely with horizontal (infectious) transmission. However, recent empirical studies indicate that some sex-ratio distorting parasites have retained the capability for horizontal transmission. Results Numerical simulations using biologically realistic parameters suggest that a feminising parasite is only likely to lose the capability for horizontal transmission if its host occurs at low density and/or has a male-biased primary sex ratio. It is also demonstrated that even a small amount of horizontal transmission can allow multiple feminising parasites to coexist within a single host population. Finally it is shown that, by boosting its host's rate of population growth, a feminising parasite can increase its own horizontal transmission and allow the invasion of other, more virulent parasites. Conclusions The prediction that sex-ratio distorting parasites are likely to retain a degree of horizontal transmission has important implications for the epidemiology and host-parasite interactions of these organisms. It may also explain the frequent co-occurrence of several sex-ratio distorting parasite species in nature. PMID:22188680

2011-01-01

375

Image ratio features for facial expression recognition application.  

PubMed

Video-based facial expression recognition is a challenging problem in computer vision and human-computer interaction. To target this problem, texture features have been extracted and widely used, because they can capture image intensity changes raised by skin deformation. However, existing texture features encounter problems with albedo and lighting variations. To solve both problems, we propose a new texture feature called image ratio features. Compared with previously proposed texture features, e.g., high gradient component features, image ratio features are more robust to albedo and lighting variations. In addition, to further improve facial expression recognition accuracy based on image ratio features, we combine image ratio features with facial animation parameters (FAPs), which describe the geometric motions of facial feature points. The performance evaluation is based on the Carnegie Mellon University Cohn-Kanade database, our own database, and the Japanese Female Facial Expression database. Experimental results show that the proposed image ratio feature is more robust to albedo and lighting variations, and the combination of image ratio features and FAPs outperforms each feature alone. In addition, we study asymmetric facial expressions based on our own facial expression database and demonstrate the superior performance of our combined expression recognition system. PMID:19884092

Song, Mingli; Tao, Dacheng; Liu, Zicheng; Li, Xuelong; Zhou, Mengchu

2010-06-01

376

Eccentric crank variable compression ratio mechanism  

DOEpatents

A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

Lawrence, Keith Edward (Kobe, JP); Moser, William Elliott (Peoria, IL); Roozenboom, Stephan Donald (Washington, IL); Knox, Kevin Jay (Peoria, IL)

2008-05-13

377

Sex ratios in sexually dimorphic umbelliferae  

Microsoft Academic Search

Sex ratios in 35 inflorescence and plant counts of perennial, sexually dimorphic Umbelliferae vary from 0·96 to 87·33 times as many males as females. The ranges of ratios are similar in dioecious and gynodioecious populations.In 10 populations in which both the inflorescences and plants were counted, the male\\/female ratios are approximately one in populations in which the plants produce only

David G Lloyd

1973-01-01

378

Sex ratio at birth in Croatia: update.  

PubMed

There is strong evidence that the sex ratio at birth is partially determined by environmental and social factors. The modern change in those factors serves as an explanation for the secular decline in sex ratio at birth in most of the industrialized countries. This article is the reexamination of the results from my previous communication in which no trend in sex ratio at birth was established for the Croatian data from 1946 to 2007. The data for the years 2008 to 2011 were added, which didn't result with the detection of a significant change in sex ratio at birth by the regression analysis or by the Box-Jenkins time series analysis. Although the numerous factors associated with the decline in sex ratio at birth did occur during the studied period (e.g. increased exposure to the environmental pollution through food, air and water, the rise of the obesity and diabetes incidence, the economic crisis etc.), it appears that none of them made the measurable impact on sex ratio at birth. Also, the possible marginally significant decline in sex ratio at birth could be the result of a high sex ratio at birth immediately after the World War II. The results of this study caution against rapid generalization of the factors found to influence the sex ratio at birth in the epidemiological and clinical studies on the population level data. PMID:25144988

Pavi?, Dario

2014-06-01

379

Aspect Ratio Independent Etching: Fact or Fantasy?  

NASA Astrophysics Data System (ADS)

The scaling of anisotropic plasma etch rates with feature dimensions is an important issue when fabricating microelectronic and photonic devices. For a wide rage of conditions, etch rates are found to scale primarily with the feature depth/width or aspect ratio. Features with large aspect ratios etch more slowly than those with low aspect ratios regardless of feature width. However, in the presence of etch inhibitors, the scaling of etching rates with feature dimensions becomes more complicated. Smaller aspect ratio features may etch more slowly than larger aspect ratio features suggesting that etch-inhibiting chemistry could be exploited in achieving the here-to-fore elusive goal of aspect ratio independent etching (ARIE). Using a well-established etching model, based on Langmuir adsorption kinetics, we derive the etch inhibitor flux and surface adsorption parameters required to achieve ARIE. Although the required parameters are non-physical when the range of aspect ratios is unconstrained, it is possible to achieve ARIE over a restricted range of aspect ratios. However, the balance required between ion, etchant, and inhibitor fluxes is a fragile one. The best approach to minimizing the variation in etching rate with aspect ratio is to operate a high density plasma at low pressure with high neutral flow rates.

Bailey, Andrew D., III; Gottscho, Richard

1995-04-01

380

Cross contamination in dual inlet isotope ratio mass spectrometers  

Microsoft Academic Search

Since the early days of geochemical isotope ratio mass spectrometry there has always been the problem of cross contamination, i.e. the contamination of the sample gas with traces of reference gas (and vice versa) in a dual inlet system and the analyzer itself. This was attributable to valve leakages and could be corrected for. In modern leak-free machines this problem

H. A. J. Meijer; R. E. M. Neubert; G. H. Visser

2000-01-01

381

TOKAMAK REACTOR DESIGNS AS A FUNCTION OF ASPECT RATIO  

E-print Network

.2 to 6. By using ARIES-RS and ARIES-ST as reference design points, a fusion reactor system code was used projected. At the same time, based on the series of conceptual reactor point designs, the geometricGA­A23168 TOKAMAK REACTOR DESIGNS AS A FUNCTION OF ASPECT RATIO by C.P.C. WONG and R.D. STAMBAUGH

California at Los Angeles, University of

382

Wide acceptance angle, high concentration ratio, optical collector  

Microsoft Academic Search

The invention is directed to an optical collector requiring a wide acceptance angle, and a high concentration ratio. The invention is particularly adapted for use in solar collectors of cassegrain design. The optical collector system includes a parabolic circular concave primary mirror and a hyperbolic circular convex secondary mirror. The primary mirror includes a circular hole located at its center

Mark Arthur Kruer

1990-01-01

383

Atmospheric helium isotope ratio: Possible temporal and spatial variations  

NASA Astrophysics Data System (ADS)

The atmospheric 3He/ 4He ratio has been considered to be constant on a global scale, because the residence time of helium is significantly longer than the mixing time in the atmosphere. However, this ratio may be decreasing with time owing to the anthropogenic release of crustal helium from oil and natural gas wells, although this observation has been disputed. Here, we present the 3He/ 4He ratios of old air trapped in historical slags in Japan and of modern surface air samples collected at various sites around the world, measured with a newly developed analytical system. In air helium extracted from metallurgical slag found at refineries in operation between AD 1603 and 1907 in Japan, we determined a mean 3He/ 4He ratio of (5106 ± 108) × 10 -5 R HESJ (where R HESJ is the 3He/ 4He ratio of the Helium Standard of Japan), which is consistent with the previously reported value of (5077 ± 59) × 10 -5 R HESJ for historical slags in France and United Arab Emirates and about 4% higher than that of average modern air, (4901 ± 4) × 10 -5 R HESJ. This result implies that the air 3He/ 4He ratio has decreased with time as expected by anthropogenic causes. Our modern surface air samples revealed that the 3He/ 4He ratio increases from north to south at a rate of (0.16 ± 0.08) × 10 -5 R HESJ/degree of latitude, suggesting that the low 3He/ 4He ratio originates in high-latitude regions of the northern hemisphere, which is consistent with the fact that most fossil fuel is extracted and consumed in the northern hemisphere.

Sano, Yuji; Furukawa, Yukiko; Takahata, Naoto

2010-09-01

384

Thermal photons to dileptons ratio at LHC  

E-print Network

It is shown that the ratio of transverse momentum (p_T) distribution of thermal photons to dileptons produced in heavy ion collisions reaches a plateau above p_T=1 GeV. We argue that the value of the ratio in the plateau region can be used to estimate the initial temperature.

Jajati K. Nayak; Jan-e Alam; Sourav Sarkar; Bikash Sinha

2007-05-24

385

Calculating Obscuration Ratios Of Contaminated Surfaces  

NASA Technical Reports Server (NTRS)

Equations derived to estimate obscuration ratios of surfaces contaminated by particles. Ratio is fraction of surface area covered by particles. Useful as index of cleanliness in clean-room operations in manufacturing of semiconductor devices, magnetic recording media, optical devices, and pharmaceutical and biotechnological products.

Barengoltz, Jack B.

1989-01-01

386

Economy Track: Employment to Population Ratio  

NSDL National Science Digital Library

Time plot compares the employment-population ratio - the broadest measure of people who are working in America. Allows to compare between recessions, also allows to compare between demographic groups -- by sex, race/ethnicity and educational attainment. Also shows the secular trend for employment-population ratio since 1973.

Economic Policy Institute

387

Analog Implementation of Ratio Spectrum Computation  

E-print Network

by plotting the ratio of the power of a low-pass filtered signal to the power of the original unfiltered to the power spectrum of a signal, the ratio spectrum provides a number of computational advantages. One major such an analog VLSI implementation are discussed in this paper. I. INTRODUCTION The power spectrum is fundamental

Harris, John G.

388

Osmosis and Surface Area to Volume Ratio.  

ERIC Educational Resources Information Center

Describes an experiment designed to help students understand the concepts of osmosis and surface area to volume ratio (SA:VOL). The task for students is to compare water uptake in different sizes of potato cubes and relate differences to their SA:VOL ratios. (JN)

Barrett, D. R. B.

1984-01-01

389

Line Ratio Imaging of a Gas Discharge  

NASA Technical Reports Server (NTRS)

The intensity ratio of two atomic or ionic spectral lines in a plasma is a function of electron temperature. By imaging two spectral lines, and computing the line ratio, pixel by pixel, an image of the electron temperature is produced. This is demonstrated using a dusty plasma consisting of submicron particles suspended in an argon RF glow discharge.

Samsonov, D.; Goree, J.; Rogers, Rick (Technical Monitor)

1999-01-01

390

Manganese nodules: thorium-230: protactinium-231 ratios.  

PubMed

The Th(230): Pa(231) activity ratio in 7 of 11 manganese nodules is less than 10.8, the theoretical production ratio of activities in the ocean. This finding indicates difierential accumulation of these nuclides in authigenic deposits of manganese-iron oxide. PMID:17778807

Sackett, W M

1966-11-01

391

CCSSM Challenge: Graphing Ratio and Proportion  

ERIC Educational Resources Information Center

A renewed emphasis was placed on ratio and proportional reasoning in the middle grades in the Common Core State Standards for Mathematics (CCSSM). The expectation for students includes the ability to not only compute and then compare and interpret the results of computations in context but also interpret ratios and proportions as they are…

Kastberg, Signe E.; D'Ambrosio, Beatriz S.; Lynch-Davis, Kathleen; Mintos, Alexia; Krawczyk, Kathryn

2013-01-01

392

Recent studies of avian sex ratios  

Microsoft Academic Search

Sex allocation theory, and its success in predicting sex ratios in such taxa as parasitoid wasps, is often cited as one of the crowning achievements of theoretical evolutionary biology. Its success in some vertebrate taxa, particularly birds, has been more modest. I discuss two reasons for this. First, it is difficult to obtain avian sex ratio data before substantial offspring

Ben C Sheldon

1998-01-01

393

Ratio model serves suprathreshold color luminance discrimination  

E-print Network

Ratio model serves suprathreshold color­ luminance discrimination Marcel J. Sankeralli and Kathy T the responses of the three postreceptoral mechanisms are combined to subserve discrimination of suprathreshold model of suprathreshold color­luminance dis- crimination, in which discrimination depends on a ratio

Mullen, Kathy T.

394

Sustainable sex ratio in lattice populations  

NASA Astrophysics Data System (ADS)

We present a lattice model of mating populations. Simulation is performed by two different methods: local and global interactions. Simulation results account for the reason why the observed sex ratio is nearly one half in many animals. The male-biased sex ratio, such as in human populations, is also explained.

Tainaka, K.; Hayashi, T.; Yoshimura, J.

2006-05-01

395

Gonadotrophin and the human secondary sex ratio  

Microsoft Academic Search

A review of published reports showed that the sex ratio (proportion of boys) was low among infants conceived after ovulation had been induced. The difference between the observed sex ratio and an expected one of 0 . 514 was highly significant. These findings suggest that maternal gonadotrophin concentrations at the time of conception directly affect the sex of the zygote.

W H James

1980-01-01

396

Factors affecting the Human Sex Ratio  

Microsoft Academic Search

WE present here evidence suggesting the existence of at least two kinds of factors affecting the human sex ratio. As the sex ratio we use the number of male births per 100 female births. The evidence is based on family data collected by Geissler1 in 1889 and by ourselves2,3.

K. O. Renkonen; O. Mäkelä; Raimo Lehtovaara

1962-01-01

397

Negative Poisson's ratio polymeric and metallic foams  

Microsoft Academic Search

Foam materials based on metal and several polymers were transformed so that their cellular architecture became re-entrant, i.e. with inwardly protruding cell ribs. Foams with re-entrant structures exhibited negative Poisson's ratios as well as greater resilience than conventional foams. Foams with negative Poisson's ratios were prepared using different techniques and materials and their mechanical behaviour and structure evaluated.

E. A. Friis; R. S. Lakes; J. B. Park

1988-01-01

398

Factors affecting egg ratios in planktonic rotifers  

Microsoft Academic Search

Edmondson’s egg ratio (number of amictic eggs per female) is an important life history variable, which has been in wide use to understand and predict patterns of population growth in planktonic rotifers under field conditions. It is also useful as an indicator of the health of rotifers under culture conditions. Generally, an inverse relationship exists between the egg ratio and

S. S. S. Sarma; R. D. Gulati; S. Nandini

2005-01-01

399

Hybrid LTA vehicle controllability as affected by buoyancy ratio  

NASA Technical Reports Server (NTRS)

The zero and low speed controllability of heavy lift airships under various wind conditions as affected by the buoyancy ratio are investigated. A series of three hybrid LTA vehicls were examined, each having a dynamic thrust system comprised of four H-34 helicopters, but with buoyant envelopes of different volumes (and hence buoyancies), and with varying percentage of helium inflation and varying useful loads (hence gross weights). Buoyancy ratio, B, was thus examined varying from approximately 0.44 to 1.39. For values of B greater than 1.0, the dynamic thrusters must supply negative thrust (i.e. downward).

Meyers, D. N.; Kubicki, P.; Tarczynski, T.; Fairbanks, A.; Piasecki, F. N.

1979-01-01

400

Poisson's ratio of individual metal nanowires.  

PubMed

The measurement of Poisson's ratio of nanomaterials is extremely challenging. Here we report a lateral atomic force microscope experimental method to electromechanically measure the Poisson's ratio and gauge factor of individual nanowires. Under elastic loading conditions we monitor the four-point resistance of individual metallic nanowires as a function of strain and different levels of electrical stress. We determine the gauge factor of individual wires and directly measure the Poisson's ratio using a model that is independently validated for macroscopic wires. For macroscopic wires and nickel nanowires we find Poisson's ratios that closely correspond to bulk values, whereas for silver nanowires significant deviations from the bulk silver value are observed. Moreover, repeated measurements on individual silver nanowires at different levels of mechanical and electrical stress yield a small spread in Poisson ratio, with a range of mean values for different wires, all of which are distinct from the bulk value. PMID:25000139

McCarthy, Eoin K; Bellew, Allen T; Sader, John E; Boland, John J

2014-01-01

401

High Transformer ratios in collinear wakefield accelerators.  

SciTech Connect

Based on our previous experiment that successfully demonstrated wakefield transformer ratio enhancement in a 13.625 GHz dielectric-loaded collinear wakefield accelerator using the ramped bunch train technique, we present here a redesigned experimental scheme for even higher enhancement of the efficiency of this accelerator. Design of a collinear wakefield device with a transformer ratio R2, is presented. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced transformer ratio (ETR) technique is able to increase the transformer ratio R above the ordinary limit of 2. To match the wavelength of the fundamental mode of the wakefield with the bunch length (sigmaz=2 mm) of the new Argonne wakefield accelerator (AWA) drive gun (where the experiment will be performed), a 26.625 GHz dielectric based accelerating structure is required. This transformer ratio enhancement technique based on our dielectric-loaded waveguide design will result in a compact, high efficiency accelerating structures for future wakefield accelerators.

Power, J. G.; Conde, M.; Yusof, Z.; Gai, W.; Jing, C.; Kanreykin, A.; Schoessow, P.; High Energy Physics; Euclid Techlabs, LLC

2008-01-01

402

Geometrical scaling in charm structure function ratios  

E-print Network

By using a Laplace-transform technique, we solve the next-to-leading-order master equation for charm production and derive a compact formula for the ratio $R^{c}=\\frac{F^{^{c\\overline{c}}}_L}{F^{^{c\\overline{c}}}_2}$, which is useful for extracting the charm structure function from the reduced charm cross section, in particular, at DESY HERA, at small x. Our results show that this ratio is independent of xat small x. In this method of determining the ratios, we apply geometrical scaling in charm production in deep inelastic scattering (DIS). Our analysis shows that the renormalization scales have a sizable impact on the ratio Rcat high $Q^{2}$. Our results for the ratio of the charm structure functions are in a goodagreement with some phenomenological models.

Boroun, G R

2014-01-01

403

Geometrical scaling in charm structure function ratios  

NASA Astrophysics Data System (ADS)

By using a Laplace-transform technique, we solve the next-to-leading-order master equation for charm production and derive a compact formula for the ratio Rc=FLccbar/F2ccbar, which is useful for extracting the charm structure function from the reduced charm cross section, in particular, at DESY HERA, at small x. Our results show that this ratio is independent of x at small x. In this method of determining the ratios, we apply geometrical scaling in charm production in deep inelastic scattering (DIS). Our analysis shows that the renormalization scales have a sizable impact on the ratio Rc at high Q2. Our results for the ratio of the charm structure functions are in a good agreement with some phenomenological models.

Boroun, G. R.; Rezaei, B.

2014-09-01

404

Scavenging ratios based on inflow air concentrations  

SciTech Connect

Scavenging ratios were calculated from field measurements made during April 1985. Event precipitation samples were collected at the surface, but air chemistry measurements in the air mass feeding the precipitation were made from an aircraft. In contrast, ratios calculated in previous studies have used air concentration and precipitation chemistry data from only surface measurements. Average scavenging ratios were calculated for SO{sub 4}{sup 2{minus}}, NO{sub 3}{sup {minus}}, NH{sub 4}{sup +}, total sulfate, total nitrate, and total ammonium for 5 events; the geometric mean of these scavenging ratios were 8.5 {times} 10{sup 5}, 5.6 {times} 10{sup 6}, 4.3 {times} 10{sup 5}, 3.4 {times} 10{sup 5}, 2.4 {times} 10{sup 6}, and 9.7 {times} 10{sup 4}, respectively. These means are similar to but less variable than previous ratios formed using only surface data.

Davis, W.E.; Dana, M.T.; Lee, R.N.; Slinn, W.G.N.; Thorp, J.M.

1991-07-01

405

Heavy baryon/meson ratios in relativistic heavy ion collisions  

E-print Network

Heavy baryon/meson ratios $\\Lambda_c/D^0$ and $\\Lambda_b/\\bar{B}^0$ in relativistic heavy ion collisions are studied in the quark coalescence model. For heavy baryons, we include production from coalescence of heavy quarks with free light quarks as well as with bounded light diquarks that might exist in the strongly coupled quark-gluon plasma produced in these collisions. Including the contribution from decays of heavy hadron resonances and also that due to fragmentation of heavy quarks that are left in the system after coalescence, the resulting $\\Lambda_c/D^0$ and $\\Lambda_b/\\bar{B}^0$ ratios in midrapidity ($|y|\\le 0.5$) from central Au+Au collisions at $\\sqrt{s_{NN}}=200$ GeV are about a factor of five and ten, respectively, larger than those given by the thermal model, and about a factor of ten and twelve, respectively, larger than corresponding ratios in the PYTHIA model for $pp$ collisions. These ratios are reduced by a factor of about 1.6 if there are no diquarks in the quark-gluon plasma. The transverse momentum dependence of the heavy baryon/meson ratios is found to be sensitive to the heavy quark mass, with the $\\Lambda_b/\\bar{B}^0$ ratio being much flatter than the $\\Lambda_c/D^0$ ratio. The latter peaks at the transverse momentum $p_T^{} \\simeq 0.8$ GeV but the peak shifts to $p_T^{} \\simeq 2$ GeV in the absence of diquarks.

Yongseok Oh; Che Ming Ko; Su Houng Lee; Shigehiro Yasui

2009-01-12

406

The Application of Generalized Predictive Control in CVT Speed Ratio Control  

Microsoft Academic Search

The continuously variable transmission (CVT) speed ratio system is described with a feeble nonlinear characteristic with pure time-delay by analyzing its structure and basic control principle; this is the basic reason that induces speed ratio tracking fluctuation when the common-used control algorithm is applied in this system. Aiming at this problem, a generalized predictive controller optimized by the genetic algorithm

Jingang Liu; Yunshan Zhou; Yuanchun Cai; Jianye Su; Naiwei Zou

2007-01-01

407

C/O Ratios in Exoplanetary Atmospheres  

NASA Astrophysics Data System (ADS)

Recent observations are allowing unprecedented constraints on the carbon-to-oxygen (C/O) ratios of giant exoplanetary atmospheres. Elemental abundance ratios, such as the C/O ratio, of planetary atmospheres provide important constraints on planetary interior compositions and formation conditions, and on the chemical and dynamical processes in the atmospheres. In addition, for super-Earths, the potential availability of water and oxygen, and hence the notion of `habitability', is contingent on the C/O ratio. Typically, an oxygen-rich composition, motivated by the solar nebula C/O of 0.5, is assumed in models of exoplanetary formation, interiors, and atmospheres. However, recent observations of exoplanetary atmospheres are suggesting the possibility of C/O ratios of 1.0 or higher, motivating the new class of Carbon-rich Planets (CRPs). In this talk, we will present observational constraints on atmospheric C/O ratios for an ensemble of transiting exoplanets and discuss their implications on the various aspects of exoplanetary characterization described above. Motivated by these results, we propose a two-dimensional classification scheme for irradiated giant exoplanets in which the incident irradiation and the atmospheric C/O ratio are the two dimensions. We demonstrate that some of the extreme anomalies reported in the literature for hot Jupiter atmospheres can be explained based on this 2-D scheme. An overview of new theoretical avenues and observational efforts underway for chemical characterization of extrasolar planets, from hot Jupiters to super-Earths, will be presented.

Madhusudhan, N.

2012-04-01

408

CALIPSO lidar ratio retrieval over the ocean.  

PubMed

We are demonstrating on a few cases the capability of CALIPSO to retrieve the 532 nm lidar ratio over the ocean when CloudSat surface scattering cross section is used as a constraint. We are presenting the algorithm used and comparisons with the column lidar ratio retrieved by the NASA airborne high spectral resolution lidar. For the three cases presented here, the agreement is fairly good. The average CALIPSO 532 nm column lidar ratio bias is 13.7% relative to HSRL, and the relative standard deviation is 13.6%. Considering the natural variability of aerosol microphysical properties, this level of accuracy is significant since the lidar ratio is a good indicator of aerosol types. We are discussing dependencies of the accuracy of retrieved aerosol lidar ratio on atmospheric aerosol homogeneity, lidar signal to noise ratio, and errors in the optical depth retrievals. We are obtaining the best result (bias 7% and standard deviation around 6%) for a nighttime case with a relatively constant lidar ratio (in the vertical) indicative of homogeneous aerosol type. PMID:21935239

Josset, Damien; Rogers, Raymond; Pelon, Jacques; Hu, Yongxiang; Liu, Zhaoyan; Omar, Ali; Zhai, Peng-Wang

2011-09-12

409

CALIPSO Lidar Ratio Retrieval Over the Ocean  

NASA Technical Reports Server (NTRS)

We are demonstrating on a few cases the capability of CALIPSO to retrieve the 532 nm lidar ratio over the ocean when CloudSat surface scattering cross section is used as a constraint. We are presenting the algorithm used and comparisons with the column lidar ratio retrieved by the NASA airborne high spectral resolution lidar. For the three cases presented here, the agreement is fairly good. The average CALIPSO 532 nm column lidar ratio bias is 13.7% relative to HSRL, and the relative standard deviation is 13.6%. Considering the natural variability of aerosol microphysical properties, this level of accuracy is significant since the lidar ratio is a good indicator of aerosol types. We are discussing dependencies of the accuracy of retrieved aerosol lidar ratio on atmospheric aerosol homogeneity, lidar signal to noise ratio, and errors in the optical depth retrievals. We are obtaining the best result (bias 7% and standard deviation around 6%) for a nighttime case with a relatively constant lidar ratio (in the vertical) indicative of homogeneous aerosol type

Josset, Damien B.; Rogers, Raymond R.; Pelon, Jacques; Hu, Yongxiang; Liu, Zhaoyan; Omar, Ali H.; Zhai, Peng-Wang

2011-01-01

410

Musical Ratios in Sounds from the Human Cochlea  

PubMed Central

The physiological roots of music perception are a matter of long-lasting debate. Recently light on this problem has been shed by the study of otoacoustic emissions (OAEs), which are weak sounds generated by the inner ear following acoustic stimulation and, sometimes, even spontaneously. In the present study, a high-resolution time–frequency method called matching pursuit was applied to the OAEs recorded from the ears of 45 normal volunteers so that the component frequencies, amplitudes, latencies, and time-spans could be accurately determined. The method allowed us to find that, for each ear, the OAEs consisted of characteristic frequency patterns that we call resonant modes. Here we demonstrate that, on average, the frequency ratios of the resonant modes from all the cochleas studied possessed small integer ratios. The ratios are the same as those found by Pythagoras as being most musically pleasant and which form the basis of the Just tuning system. The statistical significance of the results was verified against a random distribution of ratios. As an explanatory model, there are attractive features in a recent theory that represents the cochlea as a surface acoustic wave resonator; in this situation the spacing between the rows of hearing receptors can create resonant cavities of defined lengths. By adjusting the geometry and the lengths of the resonant cavities, it is possible to generate the preferred frequency ratios we have found here. We conclude that musical perception might be related to specific geometrical and physiological properties of the cochlea. PMID:22655092

Blinowska, Katarzyna J.; Kwaskiewicz, Konrad; Jedrzejczak, W. Wiktor; Skarzynski, Henryk

2012-01-01

411

Musical ratios in sounds from the human cochlea.  

PubMed

The physiological roots of music perception are a matter of long-lasting debate. Recently light on this problem has been shed by the study of otoacoustic emissions (OAEs), which are weak sounds generated by the inner ear following acoustic stimulation and, sometimes, even spontaneously. In the present study, a high-resolution time-frequency method called matching pursuit was applied to the OAEs recorded from the ears of 45 normal volunteers so that the component frequencies, amplitudes, latencies, and time-spans could be accurately determined. The method allowed us to find that, for each ear, the OAEs consisted of characteristic frequency patterns that we call resonant modes. Here we demonstrate that, on average, the frequency ratios of the resonant modes from all the cochleas studied possessed small integer ratios. The ratios are the same as those found by Pythagoras as being most musically pleasant and which form the basis of the Just tuning system. The statistical significance of the results was verified against a random distribution of ratios. As an explanatory model, there are attractive features in a recent theory that represents the cochlea as a surface acoustic wave resonator; in this situation the spacing between the rows of hearing receptors can create resonant cavities of defined lengths. By adjusting the geometry and the lengths of the resonant cavities, it is possible to generate the preferred frequency ratios we have found here. We conclude that musical perception might be related to specific geometrical and physiological properties of the cochlea. PMID:22655092

Blinowska, Katarzyna J; Kwaskiewicz, Konrad; Jedrzejczak, W Wiktor; Skarzynski, Henryk

2012-01-01

412

The HNC/HCN Ratio in Star-forming Regions  

NASA Astrophysics Data System (ADS)

HNC and HCN, typically used as dense gas tracers in molecular clouds, are a pair of isomers that have great potential as a temperature probe because of temperature dependent, isomer-specific formation and destruction pathways. Previous observations of the HNC/HCN abundance ratio show that the ratio decreases with increasing temperature, something that standard astrochemical models cannot reproduce. We have undertaken a detailed parameter study on which environmental characteristics and chemical reactions affect the HNC/HCN ratio and can thus contribute to the observed dependence. Using existing gas and gas-grain models updated with new reactions and reaction barriers, we find that in static models the H + HNC gas-phase reaction regulates the HNC/HCN ratio under all conditions, except for very early times. We quantitatively constrain the combinations of H abundance and H + HNC reaction barrier that can explain the observed HNC/HCN temperature dependence and discuss the implications in light of new quantum chemical calculations. In warm-up models, gas-grain chemistry contributes significantly to the predicted HNC/HCN ratio and understanding the dynamics of star formation is therefore key to model the HNC/HCN system.

Graninger, Dawn M.; Herbst, Eric; Öberg, Karin I.; Vasyunin, Anton I.

2014-05-01

413

Retrieved waste properties and high-level waste critical component ratios for privatization waste feed delivery  

SciTech Connect

The purpose for this document is to provide the basis for the retrieved waste properties and high-level waste critical component ratios specified in the System Specification for the Double-Shell Tank System.

Peters, B.B.

1998-03-04

414

Optimal sampling ratios in comparative diagnostic trials  

PubMed Central

Summary A subjective sampling ratio between the case and the control groups is not always an efficient choice to maximize the power or to minimize the total required sample size in comparative diagnostic trials.We derive explicit expressions for an optimal sampling ratio based on a common variance structure shared by several existing summary statistics of the receiver operating characteristic curve. We propose a two-stage procedure to estimate adaptively the optimal ratio without pilot data. We investigate the properties of the proposed method through theoretical proofs, extensive simulation studies and a real example in cancer diagnostic studies. PMID:24948841

Dong, Ting; Tang, Liansheng Larry; Rosenberger, William F.

2014-01-01

415

TIGHT ASPECT RATIO TOKAMAKS - THEORY AND EXPERIMENT  

SciTech Connect

The START (Small Tight Aspect Ratio Tokamak) experiment became operational in January 1991 at AEA Fusion Culham Laboratory. It is the only tokamak producing hot plasmas at aspect ratios as low as A = R/a approximately 1.3, and is providing valuable insight into the physical processes (such as toroidicity and trapping) involved at low aspect ratio. Three topics are discussed in this paper: equilibrium properties, including evidence of neo-classical and bootstrap effects; energy confinement studies; and MHD properties, including possible explanations for the apparent absence of the major disruption at low A.

Sykes, A [Culham Centre for Fusion Energy, Culham, UK; Peng, Yueng Kay Martin [ORNL

1993-01-01

416

The effect of SiO2/Al2O3 ratio on the structure and microstructure of the glazes from SiO2-Al2O3-CaO-MgO-Na2O-K2O system  

NASA Astrophysics Data System (ADS)

Ceramic glazes are commonly used to covering of the facing surface of ceramics ware. A well-chosen oxide composition and firing conditions of glazes causes significant improvement of technical parameters of ceramic products. Modern glazes are classified as glass-ceramic composites with different crystalline phases arising during firing. The presence of crystals in the glass matrix is influenced by many factors, especially by oxides molar composition. A crucial role is played by the molar ratio of SiO2/Al2O3. In this work the six composition of glazes from SiO2-Al2O3-CaO-MgO-Na2O-K2O system were examined. The only variable is the ratio of the silicon oxideto alumina at a constant content of other components: MgO, CaO, K2O, Na2O, ZnO. In order to determine the real phase composition of the obtained glazes research on fluorescence spectrometer (XRF) were done. For structural studies X-ray diffraction (XRD) and spectroscopic in the middle infrared (MIR) were performed. In order to determine the state of the surface (microstructure) research on the scanning electron microscope (SEM) with EDX. The research allowed to determine the influence of SiO2/Al2O3 ratio on the structure and phase composition of glazes and the nature, and type of formed crystalline phases.

Partyka, Janusz; Sitarz, Maciej; Le?niak, Magdalena; Gasek, Katarzyna; Jele?, Piotr

2015-01-01

417

Enhanced nutrient removal in a modified step feed process treating municipal wastewater with different inflow distribution ratios and nutrient ratios.  

PubMed

A pilot-scale modified step feed process was proposed to enhance organics and nutrient (N and P) removal performance from municipal wastewater. It combined University of Cape Town (UCT) and step feed process. Effects of inflow distribution ratios and nutrients ratios were investigated. The highest removal efficiencies of 89% for chemical oxygen demanding (COD), 88% for total nitrogen (TN) and 93% for phosphorus were obtained, respectively, at the inflow distribution ratio of 40:30:30%. The phosphorus removal exhibited an upward trend with the increasing of influent COD/P and TN/P, and the nitrogen removal had a positive correlation with influent COD/TN. In addition, aerobic simultaneous nitrification and denitrification and anoxic denitrifying phosphorus uptake made a distinct contribution to enhance nutrient removal. The proposed system was demonstrated to be an attractive enhanced biological nutrient removal process for wastewater treatment plants due to relatively high nutrient removal, robust sludge settleability and energy savings. PMID:20650632

Ge, Shijian; Peng, Yongzhen; Wang, Shuying; Guo, Jianhua; Ma, Bin; Zhang, Liang; Cao, Xu

2010-12-01

418

Detrended minimum-variance hedge ratio: A new method for hedge ratio at different time scales  

NASA Astrophysics Data System (ADS)

In this paper, based on the detrended fluctuation analysis (DFA) method and the detrended cross-correlation analysis (DCCA) method, we propose an improved method of minimum-variance (MV) hedge ratio, i.e., the detrended minimum-variance (D-MV) hedge ratio, which can measure the hedge ratio at different time scales. The proposed D-MV hedge ratio is defined as the detrended covariance function between spot and futures returns divided by the detrended variance function of futures returns. Through the simulated and empirical analysis, we find that (i) the outcomes of the hedge ratio and the corresponding hedging effectiveness for the D-MV hedge ratio are diverse at different time scales, which can meet needs of various hedging participants with different hedging horizons; (ii) our proposed D-MV hedge ratio has a better hedging performance and a greater potential to determine the hedge ratio because its results of hedging effectiveness at most of time scales are better than those of the traditional MV hedge ratio; and (iii) as for the method of D-MV hedge ratio for different polynomial orders m in the fitting procedure, the D-MV-1 hedge ratio (i.e., the linear polynomial in the fitting procedure) has the best hedging capability for determining the hedge ratio.

Wang, Gang-Jin; Xie, Chi; He, Ling-Yun; Chen, Shou

2014-07-01

419

Nonlinear Analysis of the Poisson's Ratio of Negative Poisson's Ratio Foams  

Microsoft Academic Search

This article contains an analytic study of Poisson's ratio of re-entrant foam materials with negative Poisson's ratio. These materials get fatter when stretched and thinner when compressed. The Poisson effect is so fundamentally important to the properties of a material that a large change in the value of the ratio will have significant effects on the material's mechanical performance. Isotropic

J. B. Choi; R. S. Lakes

1995-01-01

420

Science Application of Area and Ratio Concepts  

ERIC Educational Resources Information Center

This article describes using area and ratio concepts to examine why some animals, or people wearing different types of shoes, sink into the surface on which they are standing. Students compute "sinking values" to explain these differences. (Contains 2 figures.)

Horak, Virginia M.

2006-01-01

421

Optimizing combination chemotherapy by controlling drug ratios.  

PubMed

Cancer chemotherapy treatments typically employ drug combinations in which the dose of each agent is pushed to the brink of unacceptable toxicity; however, emerging evidence indicates that this approach may not be providing optimal efficacy due to the manner in which drugs interact. Specifically, whereas certain ratios of combined drugs can be synergistic, other ratios of the same agents may be antagonistic, implying that the most efficacious combinations may be those that utilize certain agents at reduced doses. Advances in nano-scale drug delivery vehicles now enable the translation of in vitro information on synergistic drug ratios into improved anticancer combination therapies in which the desired drug ratio can be controlled and maintained following administration in vivo, so that synergistic effects can be exploited. This "ratiometric" approach to combination chemotherapy opens new opportunities to enhance the effectiveness of existing and future treatment regimens across a spectrum of human diseases. PMID:17827442

Mayer, Lawrence D; Janoff, Andrew S

2007-08-01

422

INVESTIGATION Genome Scans for Transmission Ratio  

E-print Network

INVESTIGATION Genome Scans for Transmission Ratio Distortion Regions in Mice Joaquim Casellas,*,,1, University of California, Davis, California 95616-8521, Departments of Medicine, Biochemistry and Molecular Genetics and Center for Public Health Genomics, University of Virginia, Charlottesville, Virginia 22908

Yandell, Brian S.

423

Bootstrap confidence intervals for ratios of expectations  

Microsoft Academic Search

We are concerned with computing a confidence interval for the ratio E[Y]\\/E[X, where (X,Y) is a pair of random variables. This ratio estimation problem arises in, for instance, regenerative simulation. As an alternative to confidence intervals based on asymptotic normality, we study and compare different variants of the bootstrap for one-sided and two-sided intervals. We point out situations where these

Denis Choquet; Pierre L'ecuyer; Christian Léger

1999-01-01

424

Does inbreeding distort sex-ratios?  

Microsoft Academic Search

Inbreeding is reputed to distort sex-ratios by reducing the proportion of the homogametic sex. However, many data sets do not show such an effect, and there is a known selective publication bias. To resolve the issue, we (a) developed detailed theoretical expectations for the effects of inbreeding on sex-ratios for autosomal and sex-linked loci with sex-limited effects or with equal

Richard Frankham; Jonathan Wilcken

2006-01-01

425

Approaches to high aspect ratio triangulations  

NASA Technical Reports Server (NTRS)

In aerospace computational fluid dynamics calculations, high aspect ratio, or stretched, triangulations are necessary to adequately resolve the features of a viscous flow around bodies. In this paper, we explore alternatives to the Delaunay triangulation which can be used to generate high aspect ratio triangulations of point sets. The method is based on a variation of the lifting map concept which derives Delaunay triangulations from convex hull calculations.

Posenau, M.-A.

1993-01-01

426

Posterior odds ratios for selected regression hypotheses  

Microsoft Academic Search

Summary  Bayesian posterior odds ratios for frequently encountered hypotheses about parameters of the normal linear multiple regression\\u000a model are derived and discussed. For the particular prior distributions utilized, it is found that the posterior odds ratios\\u000a can be well approximated by functions that are monotonic in usual sampling theoryF statistics. Some implications of this finding and the relation of our work

A. Zellner; A. Siow

1980-01-01

427

Secular trends in human sex ratios  

Microsoft Academic Search

Secular change in sex ratios is examined in relation to experience in the family. Two theoretical perspectives are outlined:\\u000a Guttentag and Secord’s (1983) adaptation of social exchange theory, and sexual selection theory. Because of large-scale change\\u000a in number of births and typical age differentials between men and women at marriage, low sex ratios at couple formation ages\\u000a existed in the

Frank A. Pedersen

1991-01-01

428

Plutonium isotope ratio variations in North America  

SciTech Connect

Historically, approximately 12,000 TBq of plutonium was distributed throughout the global biosphere by thermo nuclear weapons testing. The resultant global plutonium fallout is a complex mixture whose {sup 240}Pu/{sup 239}Pu atom ratio is a function of the design and yield of the devices tested. The average {sup 240}Pu/{sup 239}Pu atom ratio in global fallout is 0.176 + 014. However, the {sup 240}Pu/{sup 239}Pu atom ratio at any location may differ significantly from 0.176. Plutonium has also been released by discharges and accidents associated with the commercial and weapons related nuclear industries. At many locations contributions from this plutonium significantly alters the {sup 240}Pu/{sup 239}Pu atom ratios from those observed in global fallout. We have measured the {sup 240}Pu/{sup 239}Pu atom ratios in environmental samples collected from many locations in North America. This presentation will summarize the analytical results from these measurements. Special emphasis will be placed on interpretation of the significance of the {sup 240}Pu/{sup 239}Pu atom ratios measured in environmental samples collected in the Arctic and in the western portions of the United States.

Steiner, Robert E [Los Alamos National Laboratory; La Mont, Stephen P [Los Alamos National Laboratory; Eisele, William F [Los Alamos National Laboratory; Fresquez, Philip R [Los Alamos National Laboratory; Mc Naughton, Michael [Los Alamos National Laboratory; Whicker, Jeffrey J [Los Alamos National Laboratory

2010-12-14

429

In vivo dissolution measurement with indium-111 summation peak ratios  

SciTech Connect

Dissolution of (/sup 111/In)labeled tablets was measured in vivo in a totally noninvasive manner by using a modification of the perturbed angular correlation technique known as the summation peak ratio method. This method, which requires the incorporation of only 10-12 microCi into the dosage form, provided reliable dissolution data after oral administration of (/sup 111/In)lactose tablets. These results were supported by in vitro experiments which demonstrated that the dissolution rate as measured by the summation peak ratio method was in close agreement with the dissolution rate of salicylic acid in a (/sup 111/In)salicylic acid tablet. The method has the advantages of using only one detector, thereby avoiding the need for complex coincidence counting systems, requiring less radioactivity, and being potentially applicable to a gamma camera imaging system.

Jay, M.; Woodward, M.A.; Brouwer, K.R.

1985-10-01

430

Experimental evaluation of blockage ratio and plenum evacuation system flow effects on pressure distribution for bodies of revolution in 0.1 scale model test section of NASA Lewis Research Center's proposed altitude wind tunnel  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted in the slotted test section of the 0.1-scale model of the proposed Altitude Wind Tunnel to evaluate wall interference effects at tunnel Mach numbers from 0.70 to 0.95 on bodies of revolution with blockage rates of 0.43, 3, 6, and 12 percent. The amount of flow that had to be removed from the plenum chamber (which surrounded the slotted test section) by the plenum evacuation system (PES) to eliminate wall interference effects was determined. The effectiveness of tunnel reentry flaps in removing flow from the plenum chamber was examined. The 0.43-percent blockage model was the only one free of wall interference effects with no PES flow. Surface pressures on the forward part of the other models were greater than interference-free results and were not influenced by PES flow. Interference-free results were achieved on the aft part of the 3- and 6-percent blockage models with the proper amount of PES flow. The required PES flow was substantially reduced by opening the reentry flaps.

Burley, Richard R.; Harrington, Douglas E.

1987-01-01

431

Stretch-mediated release of angiotensin II induces myocyte apoptosis by activating p53 that enhances the local renin-angiotensin system and decreases the Bcl-2-to-Bax protein ratio in the cell.  

PubMed Central

Physical forces activate apoptosis and gene expression, but the mechanism is unknown. For this purpose, adult myocytes were stretched in an equibiaxial stretch apparatus and the magnitude of cell death was examined 4 and 24 h later. The possibility of stretch-mediated activation of p53 and p53-dependent genes was evaluated at 30 min, 2, 4, 8, and 24 h. Myocyte apoptosis increased by 4.4- and 7.6-fold at 4 and 24 h after stretch. p53 binding to the promoter of angiotensinogen, AT1 receptor, and Bax also increased. Expression of angiotensinogen, AT1 receptor, p53, and Bax increased and Bcl-2 decreased in stretched myocytes. The changes in AT1 receptor, p53, Bax, and Bcl-2 became more apparent with the duration of stretch. Angiotensin II concentration in the medium increased at 10 min, reaching maximal levels at 1 and 20 h. The AT1 blocker, losartan, abolished apoptosis in stretched myocytes. Myocyte volume was not influenced by stretch. In conclusion, stretch-mediated release of angiotensin II is coupled with apoptosis and the activation of p53 which may be responsible for the prolonged upregulation of the local renin-angiotensin system and the increased susceptibility of myocytes to undergo apoptosis. PMID:9525975

Leri, A; Claudio, P P; Li, Q; Wang, X; Reiss, K; Wang, S; Malhotra, A; Kajstura, J; Anversa, P

1998-01-01

432

Developmental basis of sexually dimorphic digit ratios  

PubMed Central

Males and females generally have different finger proportions. In males, digit 2 is shorter than digit 4, but in females digit 2 is the same length or longer than digit 4. The second- to fourth-digit (2D:4D) ratio correlates with numerous sexually dimorphic behavioral and physiological conditions. Although correlational studies suggest that digit ratios reflect prenatal exposure to androgen, the developmental mechanism underlying sexually dimorphic digit development remains unknown. Here we report that the 2D:4D ratio in mice is controlled by the balance of androgen to estrogen signaling during a narrow window of digit development. Androgen receptor (AR) and estrogen receptor ? (ER-?) activity is higher in digit 4 than in digit 2. Inactivation of AR decreases growth of digit 4, which causes a higher 2D:4D ratio, whereas inactivation of ER-? increases growth of digit 4, which leads to a lower 2D:4D ratio. We also show that addition of androgen has the same effect as inactivation of ER and that addition of estrogen mimics the reduction of AR. Androgen and estrogen differentially regulate the network of genes that controls chondrocyte proliferation, leading to differential growth of digit 4 in males and females. These studies identify previously undescribed molecular dimorphisms between male and female limb buds and provide experimental evidence that the digit ratio is a lifelong signature of prenatal hormonal exposure. Our results also suggest that the 2D:4D ratio can serve as an indicator of disrupted endocrine signaling during early development, which may aid in the identification of fetal origins of adult diseases. PMID:21896736

Zheng, Zhengui; Cohn, Martin J.

2011-01-01

433

Remote identification of soil conditions with ratioed multispectral data  

NASA Technical Reports Server (NTRS)

Some of the information concerning soils that a multispectral scanner system may provide is discussed, and a practical approach for realizing this potential is suggested. Some reflectance and emittance characteristics of soil surfaces are reviewed, and the feasibility of selectively enhancing contrasts associated with differing soil conditions is demonstrated. The simplicity of the proposed ratio technique, its relative economy, and the compatibility of the image output with conventional survey methods commends it for consideration as an operational method.

Wagner, T. W.; Dillman, R.; Thomson, F.

1973-01-01

434

Thermosolutal convection in high-aspect-ratio enclosures  

NASA Technical Reports Server (NTRS)

Convection in high-aspect-ratio rectangular enclosures with combined horizontal temperature and concentration gradients is studied experimentally. An electrochemical system is employed to impose the concentration gradients. The solutal buoyancy force either opposes or augments the thermal buoyancy force. Due to a large difference between the thermal and solutal diffusion rates the flow possesses double-diffusive characteristics. Various complex flow patterns are observed with different experimental conditions.

Wang, L. W.; Chen, C. T.

1988-01-01

435

Accretion disc dynamics in extreme mass ratio compact binaries  

E-print Network

An analysis is presented of a numerical investigation of the dynamics and geometry of accretion discs in binary systems with mass ratios q < 0.1, applicable to ultra-compact X-ray binaries, AM CVn stars and very short period cataclysmic variables. The steady-state geometry of the disc in the binary reference frame is found to be quite different from that expected at higher mass ratios. For q ~ 0.1, the disc takes on the usual elliptical shape, with the major axis aligned perpendicular to the line of centres of the two stars. However, at smaller mass ratios the elliptical gaseous orbits in the outer regions of the disc are rotated in the binary plane. The angle of rotation increases with gas temperature, but is found to vary inversely with q. At q = 0.01, the major axis of these orbits is aligned almost parallel to the line of centres of the two stars. These effects may be responsible for the similar disc structure inferred from Doppler tomography of the AM CVn star GP Com (Morales-Rueda et al. 2003), which has q = 0.02. The steady-state geometry at low mass ratios is not predicted by an inviscid, restricted three-body model of gaseous orbits; it is related to the effects of tidal-viscous truncation of the disc near the Roche lobe boundary. Since the disc geometry can be inferred observationally for some systems, it is proposed that this may offer a useful diagnostic for the determination of mass ratios in ultra-compact binaries.

Michael Truss

2007-01-02

436

Serial binary interval ratios improve rhythm reproduction.  

PubMed

Musical rhythm perception is a natural human ability that involves complex cognitive processes. Rhythm refers to the organization of events in time, and musical rhythms have an underlying hierarchical metrical structure. The metrical structure induces the feeling of a beat and the extent to which a rhythm induces the feeling of a beat is referred to as its metrical strength. Binary ratios are the most frequent interval ratio in musical rhythms. Rhythms with hierarchical binary ratios are better discriminated and reproduced than rhythms with hierarchical non-binary ratios. However, it remains unclear whether a superiority of serial binary over non-binary ratios in rhythm perception and reproduction exists. In addition, how different types of serial ratios influence the metrical strength of rhythms remains to be elucidated. The present study investigated serial binary vs. non-binary ratios in a reproduction task. Rhythms formed with exclusively binary (1:2:4:8), non-binary integer (1:3:5:6), and non-integer (1:2.3:5.3:6.4) ratios were examined within a constant meter. The results showed that the 1:2:4:8 rhythm type was more accurately reproduced than the 1:3:5:6 and 1:2.3:5.3:6.4 rhythm types, and the 1:2.3:5.3:6.4 rhythm type was more accurately reproduced than the 1:3:5:6 rhythm type. Further analyses showed that reproduction performance was better predicted by the distribution pattern of event occurrences within an inter-beat interval, than by the coincidence of events with beats, or the magnitude and complexity of interval ratios. Whereas rhythm theories and empirical data emphasize the role of the coincidence of events with beats in determining metrical strength and predicting rhythm performance, the present results suggest that rhythm processing may be better understood when the distribution pattern of event occurrences is taken into account. These results provide new insights into the mechanisms underlining musical rhythm perception. PMID:23964258

Wu, Xiang; Westanmo, Anders; Zhou, Liang; Pan, Junhao

2013-01-01

437

Serial binary interval ratios improve rhythm reproduction  

PubMed Central

Musical rhythm perception is a natural human ability that involves complex cognitive processes. Rhythm refers to the organization of events in time, and musical rhythms have an underlying hierarchical metrical structure. The metrical structure induces the feeling of a beat and the extent to which a rhythm induces the feeling of a beat is referred to as its metrical strength. Binary ratios are the most frequent interval ratio in musical rhythms. Rhythms with hierarchical binary ratios are better discriminated and reproduced than rhythms with hierarchical non-binary ratios. However, it remains unclear whether a superiority of serial binary over non-binary ratios in rhythm perception and reproduction exists. In addition, how different types of serial ratios influence the metrical strength of rhythms remains to be elucidated. The present study investigated serial binary vs. non-binary ratios in a reproduction task. Rhythms formed with exclusively binary (1:2:4:8), non-binary integer (1:3:5:6), and non-integer (1:2.3:5.3:6.4) ratios were examined within a constant meter. The results showed that the 1:2:4:8 rhythm type was more accurately reproduced than the 1:3:5:6 and 1:2.3:5.3:6.4 rhythm types, and the 1:2.3:5.3:6.4 rhythm type was more accurately reproduced than the 1:3:5:6 rhythm type. Further analyses showed that reproduction performance was better predicted by the distribution pattern of event occurrences within an inter-beat interval, than by the coincidence of events with beats, or the magnitude and complexity of interval ratios. Whereas rhythm theories and empirical data emphasize the role of the coincidence of events with beats in determining metrical strength and predicting rhythm performance, the present results suggest that rhythm processing may be better understood when the distribution pattern of event occurrences is taken into account. These results provide new insights into the mechanisms underlining musical rhythm perception. PMID:23964258

Wu, Xiang; Westanmo, Anders; Zhou, Liang; Pan, Junhao

2013-01-01

438

Optimal aspect ratio of endocytosed spherocylindrical nanoparticle  

NASA Astrophysics Data System (ADS)

Recent simulations have demonstrated that bioparticle size and shape modulate the process of endocytosis, and studies have provided more quantitative information that the endocytosis efficiency of spherocylindrical bioparticles is decided by its aspect ratio. At the same time, the dimensions of the receptor-ligand complex have strong effects on the size-dependent exclusion of proteins within the cellular environment. However, these earlier theoretical works including simulations did not consider the effects of ligand-receptor complex dimension on the endocytosis process. Thus, it is necessary to resolve the effects of ligand-receptor complex dimension and determine the optimal aspect ratio of spherocylindrical bioparticles in the process of endocytosis. Accordingly, we proposed a continuum elastic model, of which the results indicate that the aspect ratio depends on the ligand-receptor complex dimension and the radius of the spherocylindrical bioparticle. This model provides a phase diagram of the aspect ratio of endocytosed spherocylindrical bioparticles, the larger aspect ratio of which appears in the phase diagram with increasing ligand density, and highlights the bioparticle design.

Chen, Ying-Bing; Liu, Yan-Hui; Zeng, Yan; Mao, Wei; Hu, Lin; Mao, Zong-Liang; Xu, Hou-Qiang

2015-02-01

439

A snail with unbiased population sex ratios but highly biased brood sex ratios.  

PubMed Central

Extraordinary sex ratio patterns and the underlying sex-determining mechanisms in various organisms are worth investigating, particularly because they shed light on adaptive sex-ratio adjustment. Here, we report an extremely large variation in the brood sex ratio in the freshwater snail, Pomacea canaliculata. In eight rearing series originating from three wild populations, sex ratios were highly variable among broods, ranging continuously from almost exclusively males to almost exclusively females. However, sex ratios were similar between broods from the same mating pair, indicating that sex ratio is a family trait. Irrespective of the large variations, the average sex ratios in all rearing series were not significantly different from 0.5. We argue that Fisher's adaptive sex-ratio theory can explain the equal average sex ratios, and the results, in turn, directly support Fisher's theory. Polyfactorial sex determination (in which sex is determined by three or more genetic factors) is suggested as the most likely mechanism producing the variable brood sex ratio. PMID:12614578

Yusa, Yoichi; Suzuki, Yoshito

2003-01-01

440

Kinship Institutions and Sex Ratios in India  

PubMed Central

This article explores the relationship between kinship institutions and sex ratios in India at the turn of the twentieth century. Because kinship rules vary by caste, language, religion, and region, we construct sex ratios by these categories at the district level by using data from the 1901 Census of India for Punjab (North), Bengal (East), and Madras (South). We find that the male-to-female sex ratio varied positively with caste rank, fell as one moved from the North to the East and then to the South, was higher for Hindus than for Muslims, and was higher for northern Indo-Aryan speakers than for the southern Dravidian-speaking people. We argue that these systematic patterns in the data are consistent with variations in the institution of family, kinship, and inheritance. PMID:21308567

CHAKRABORTY, TANIKA; KIM, SUKKOO

2010-01-01