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1

Design, Fabrication and Testing of an Infrared Ratio Pyrometer System for the Measurement of Gasifier Reaction Chamber Temperature  

SciTech Connect

Texaco was awarded contract DE-FC26-99FT40684 from the U.S. DOE to design, build, bench test and field test an infrared ratio pyrometer system for measuring gasifier temperature. The award occurred in two phases. Phase 1, which involved designing, building and bench testing, was completed in September 2000, and the Phase 1 report was issued in March 2001. Phase 2 was completed in 2005, and the results of the field test are contained in this final report. Two test campaigns were made. In the first one, the pyrometer was sighted into the gasifier. It performed well for a brief period of time and then experienced difficulties in keeping the sight tube open due to a slag accumulation which developed around the opening of the sight tube in the gasifier wall. In the second test campaign, the pyrometer was sighted into the top of the radiant syngas cooler through an unused soot blower lance. The pyrometer experienced no more problems with slag occlusions, and the readings were continuous and consistent. However, the pyrometer readings were 800 to 900 F lower than the gasifier thermocouple readings, which is consistent with computer simulations of the temperature distribution inside the radiant syngas cooler. In addition, the pyrometer readings were too sluggish to use for control purposes. Additional funds beyond what were available in this contract would be required to develop a solution that would allow the pyrometer to be used to measure the temperature inside the gasifier.

Tom Leininger

2005-03-31

2

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

3

Measurement performance of an optical CCD-based pyrometer system  

Microsoft Academic Search

The measurement performance of a CCD-based pyrometer system using a three-color method was evaluated for scientific and engineering metrology. The relationships between the system parameters (exposure time and sensor gain) and the intensity measurements in an integrating sphere experiment were determined for a specific CCD sensor. The pyrometer system uses the three-color method based on the intensity ratio without geometry

Tairan Fu; Zangjian Yang; Luping Wang; Xiaofang Cheng; Maohua Zhong; Congling Shi

2010-01-01

4

Measurement performance of an optical CCD-based pyrometer system  

NASA Astrophysics Data System (ADS)

The measurement performance of a CCD-based pyrometer system using a three-color method was evaluated for scientific and engineering metrology. The relationships between the system parameters (exposure time and sensor gain) and the intensity measurements in an integrating sphere experiment were determined for a specific CCD sensor. The pyrometer system uses the three-color method based on the intensity ratio without geometry calibrations. The field measurement characteristics and the effectiveness of coupling the three-color channels were investigated in terms of the temperature measurement uniformity, temperature sensitivity and temperature range of the pyrometer system in standard blackbody tests. The results showed that the temperature non-uniformity is not proportional to the intensity non-uniformity and is in the range of 0.13-2.14%. The relative temperature sensitivities of intensity ratios for different channel combinations are different, which may provide a way to improve the measurement results. The temperature range bandwidth for object with a non-uniform temperature distribution varies from 190 to 270 K for this specific CCD-based pyrometer. The performance evaluation conclusions for the system with this specific CCD sensor are general and applicable for pyrometer systems using other CCD sensors.

Fu, Tairan; Yang, Zangjian; Wang, Luping; Cheng, Xiaofang; Zhong, Maohua; Shi, Congling

2010-06-01

5

PYROLASER - PYROLASER OPTICAL PYROMETER OPERATING SYSTEM  

NASA Technical Reports Server (NTRS)

The PYROLASER package is an operating system for the Pyrometer Instrument Company's Pyrolaser. There are 6 individual programs in the PYROLASER package: two main programs, two lower level subprograms, and two programs which, although independent, function predominantly as macros. The package provides a quick and easy way to setup, control, and program a standard Pyrolaser. Temperature and emissivity measurements may be either collected as if the Pyrolaser were in the manual operations mode, or displayed on real time strip charts and stored in standard spreadsheet format for post-test analysis. A shell is supplied to allow macros, which are test-specific, to be easily added to the system. The Pyrolaser Simple Operation program provides full on-screen remote operation capabilities, thus allowing the user to operate the Pyrolaser from the computer just as it would be operated manually. The Pyrolaser Simple Operation program also allows the use of "quick starts". Quick starts provide an easy way to permit routines to be used as setup macros for specific applications or tests. The specific procedures required for a test may be ordered in a sequence structure and then the sequence structure can be started with a simple button in the cluster structure provided. One quick start macro is provided for continuous Pyrolaser operation. A subprogram, Display Continuous Pyr Data, is used to display and store the resulting data output. Using this macro, the system is set up for continuous operation and the subprogram is called to display the data in real time on strip charts. The data is simultaneously stored in a spreadsheet format. The resulting spreadsheet file can be opened in any one of a number of commercially available spreadsheet programs. The Read Continuous Pyrometer program is provided as a continuously run subprogram for incorporation of the Pyrolaser software into a process control or feedback control scheme in a multi-component system. The program requires the Pyrolaser to be set up using the Pyrometer String Transfer macro. It requires no inputs and provides temperature and emissivity as outputs. The Read Continuous Pyrometer program can be run continuously and the data can be sampled as often or as seldom as updates of temperature and emissivity are required. PYROLASER is written using the Labview software for use on Macintosh series computers running System 6.0.3 or later, Sun Sparc series computers running OpenWindows 3.0 or MIT's X Window System (X11R4 or X11R5), and IBM PC or compatibles running Microsoft Windows 3.1 or later. Labview requires a minimum of 5Mb of RAM on a Macintosh, 24Mb of RAM on a Sun, and 8Mb of RAM on an IBM PC or compatible. The Labview software is a product of National Instruments (Austin,TX; 800-433-3488), and is not included with this program. The standard distribution medium for PYROLASER is a 3.5 inch 800K Macintosh format diskette. It is also available on a 3.5 inch 720K MS-DOS format diskette, a 3.5 inch diskette in UNIX tar format, and a .25 inch streaming magnetic tape cartridge in UNIX tar format. An electronic copy of the documentation in Macintosh WordPerfect version 2.0.4 format is included on the distribution medium. Printed documentation is included in the price of the program. PYROLASER was developed in 1992.

Roberts, F. E.

1994-01-01

6

Coke guide pyrometer: a system for coke temperature measurement  

SciTech Connect

A coke guide pyrometer system is described which measures the surface temperature of the coke mass as it is pushed from the oven. Five sensors are mounted at various heights in the same vertical plane on one side of the coke guide. Fiber optic cables transmit the infrared radiation picked up by these sensors to infrared photocells which convert the radiation to electrical signals that are transmitted to a data processor. The computer produces graphs showing the temperature distribution in the coke oven vertically and horizontally and along the length of the battery from oven to oven. Isothermal contour profiles can be generated from the data. Using the data, heating imbalances can be corrected, malfunctioning flues can be located, and coke heights can be monitored to detect lost productivity due to underfilling. The system has been operating for a year on a 6 meter battery at Bethelem Steel Corporation. Graphs and isotherms are presented to show the usefulness of the data. (CKK)

Lynn, J.B.; Kisner, G.E.

1982-01-01

7

Pyrometer system for monitoring the particle impact on a substrate during a plasma spray process  

Microsoft Academic Search

A measurement system consisting of two high-speed two-colour pyrometers is described; the system is suitable for monitoring the flattening and cooling of particles on a substrate during plasma spray deposition. The first double-wavelength optical fibre pyrometer is focused 2 mm before the substrate and the other is focused on the substrate surface. The present instrument provides data on the temperature,

M. Vardelle; A. Vardelle; P. Fauchais; C. Moreau

1994-01-01

8

Pyrometer method for measuring slab temperature in a reheat furnace  

SciTech Connect

A method and apparatus to measure the temperature of a slab in a reheat furnace with increased accuracy using either a single or dual pyrometer system through use of a multiplicity of temperature correction functions involving temperatures of slab and wall, distance between a pyrometer and the slab at which it is aimed, a ratio of air and fuel supplying the furnace heat and radiation interferences. The functions are chosen by a micro-processor in the system dependent on temperature differentials, emissivity setting of the pyrometer, target distance between pyrometer and slab, and air and fuel flow rates existing and fluctuating in the system.

Rudzki, E.M.; Jackson, R.W.; Martocci, A.P.

1984-02-21

9

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

10

Multiband pyrometer uncertainty analysis and improvement  

Microsoft Academic Search

According to the energy ratio value of multi-band radiating from the measured surface, the 'true' temperature can be calculated by multi-band pyrometer. Multi-band pyrometer has many advantages: it can hardly be affected by the emission of measured surface and the environment radiation, and it has higher Signal-to-Noise Ratio and higher temperature measurement accuracy. This paper introduces the principle of a

Yongjun Yang; Xuecong Zhang; Jing Cai; Zhongyu Wang

2010-01-01

11

Closed loop control for laser micro spot welding using fast pyrometer systems  

NASA Astrophysics Data System (ADS)

Laser micro spot welding offers temperature resistant high strength contacts without filler material. However, due to varying surface absorption properties of copper, the welding quality shows poor reproducibility. To stabilize the process we set up a power control for laser micro spot welding of copper. It consists of a high speed pyrometer and an external micro controller. The subject of the investigations is to apply a constant energy amount using conduction welding to increase the process stability. Using the closed loop control, the standard deviation of pull force for overlap welds is reduced from 3.3N to 1.3N.

Stehr, T.; Hermsdorf, J.; Henning, T.; Kling, R.

12

An Improved Radiation Pyrometer  

Microsoft Academic Search

In designing a new radiation pyrometer for industrial use above the lower limit of visible radiation, consideration of ambient temperature effects, which is of much importance in modern industrial practice, was carried out by aid of mathematical analysis. In one hypothetical case, with a very sensitive type of thermopile losing heat from its hot junction by radiation alone, it is

Thos. R. Harrison; Wm. H. Wannamaker

1941-01-01

13

A multicolor imaging pyrometer  

NASA Technical Reports Server (NTRS)

A multicolor imaging pyrometer was designed for accurately and precisely measuring the temperature distribution histories of small moving samples. The device projects six different color images of the sample onto a single charge coupled device array that provides an RS-170 video signal to a computerized frame grabber. The computer automatically selects which one of the six images provides useful data, and converts that information to a temperature map. By measuring the temperature of molten aluminum heated in a kiln, a breadboard version of the device was shown to provide high accuracy in difficult measurement situations. It is expected that this pyrometer will ultimately find application in measuring the temperature of materials undergoing radiant heating in a microgravity acoustic levitation furnace.

Frish, Michael B.; Frank, Jonathan H.

1989-01-01

14

Features of application of video capture devices in television pyrometers  

Microsoft Academic Search

The results of measurements of the signal-to-noise ratio and the characteristics of analog-to-digital conversion of a typical\\u000a EasyCAP OTP-128 video capture device based on a Philips SAA7113 video processor are described. The possibility of its application\\u000a in television pyrometers and the necessity of adjusting the parameters of the video processor during calibration of the pyrometer\\u000a against a test image are

A. V. Kuznetsov; E. V. Andreeva

2011-01-01

15

Multicolor pyrometer for materials processing in space  

NASA Technical Reports Server (NTRS)

The program goals are to design, construct, and program a prototype imaging pyrometer capable of measuring the temperature distribution across the surface of a moving object suspended in space. The approach is to utilize an optical system which operates at short wavelengths compared to the peak of the blackbody spectrum for the temperature range of interest, thus minimizing errors associated with a lack of knowledge about heated sample emissivity. An analysis of the system's temperature measurement capability based on the camera's responsivity was performed and bound to be satisfactory. Details for the evolving optical design and the progress towards construction of a working model are discussed. Details of the algorithm developed for selecting the optimum colors to be used by the pyrometer are reported. Though final selection of the colors will have to await a final design of the optical system, results using a preliminary optical design are presented.

Frish, Michael; Frank, Jonathan; Beerman, Henry

1988-01-01

16

Scanning optical pyrometer for measuring temperatures in hollow cathodes  

NASA Astrophysics Data System (ADS)

Life-limiting processes in hollow cathodes are determined largely by the temperature of the electron emitter. To support cathode life assessment, a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe was developed. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used to determine the axial temperature profile. Thermocouples on the orifice plate provide measurements of the external temperature during cathode operation and are used to calibrate the pyrometer system in situ with a small oven enclosing the externally heated cathode. The diagnostic method and initial measurements of the temperature distribution in a hollow cathode are discussed.

Polk, J. E.; Marrese-Reading, C. M.; Thornber, B.; Dang, L.; Johnson, L. K.; Katz, I.

2007-09-01

17

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

18

Uncertainty of Pyrometers in a Casting Facility  

SciTech Connect

This work has established uncertainty limits for the EUO filament pyrometers, digital pyrometers, two-color automatic pyrometers, and the standards used to certify these instruments (Table 1). If symmetrical limits are used, filament pyrometers calibrated in Production have certification uncertainties of not more than {+-}20.5 C traceable to NIST over the certification period. Uncertainties of these pyrometers were roughly {+-}14.7 C before introduction of the working standard that allowed certification in the field. Digital pyrometers addressed in this report have symmetrical uncertainties of not more than {+-}12.7 C or {+-}18.1 C when certified on a Y-12 Standards Laboratory strip lamp or in a production area tube furnace, respectively. Uncertainty estimates for automatic two-color pyrometers certified in Production are {+-}16.7 C. Additional uncertainty and bias are introduced when measuring production melt temperatures. A -19.4 C bias was measured in a large 1987 data set which is believed to be caused primarily by use of Pyrex{trademark} windows (not present in current configuration) and window fogging. Large variability (2{sigma} = 28.6 C) exists in the first 10 m of the hold period. This variability is attributed to emissivity variation across the melt and reflection from hot surfaces. For runs with hold periods extending to 20 m, the uncertainty approaches the calibration uncertainty of the pyrometers. When certifying pyrometers on a strip lamp at the Y-12 Standards Laboratory, it is important to limit ambient temperature variation (23{+-}4 C), to order calibration points from high to low temperatures, to allow 6 m for the lamp to reach thermal equilibrium (12 m for certifications below 1200 C) to minimize pyrometer bias, and to calibrate the pyrometer if error exceeds vendor specifications. A procedure has been written to assure conformance.

Mee, D.K.; Elkins, J.E.; Fleenor, R.M.; Morrision, J.M.; Sherrill, M.W.; Seiber, L.E.

2001-12-07

19

Self Calibration of a 2-wavelength Pyrometer  

NASA Technical Reports Server (NTRS)

Pyrometers require calibrations to determine their instrument constants before they can be used in remote temperature measurements. These constants reflect the combined effects of detector response, the transmissivities of intervening optical media (windows and gases) and the emissivity of the measured surface. We describe here the principal and the demonstration of self calibrating 2-wavelength pyrometer.

Ng, Daniel

1998-01-01

20

Multi-band pyrometer uncertainty analysis and improvement  

NASA Astrophysics Data System (ADS)

According to the energy ratio value of multi-band radiating from the measured surface, the 'true' temperature can be calculated by multi-band pyrometer. Multi-band pyrometer has many advantages: it can hardly be affected by the emission of measured surface and the environment radiation, and it has higher Signal-to-Noise Ratio and higher temperature measurement accuracy. This paper introduces the principle of a multi-band pyrometer and the uncertainty of measurement result is evaluated by using Monte-Carlo Method (MCM). The result shows that the accuracy of effective wavelength is the largest source of uncertainty and the other main source is reference temperature. When using ordinary blackbody furnace with continuous temperature, which can provide reference temperature and calibrate effective wavelength, the uncertainty component is 2.17K and 2.48K respectively. The combined standard uncertainty is 3.30K. A new calibration method is introduced. The effective wavelength is calibrated by monochromator, and the reference temperature is provided by fixed point black body furnace. The uncertainty component is decreased to 0.73K and 0.12K respectively. The measurement uncertainty is decreased to 0.74K. The temperature measurement accuracy is enhanced.

Yang, Yongjun; Zhang, Xuecong; Cai, Jing; Wang, Zhongyu

2011-05-01

21

Multi-band pyrometer uncertainty analysis and improvement  

NASA Astrophysics Data System (ADS)

According to the energy ratio value of multi-band radiating from the measured surface, the 'true' temperature can be calculated by multi-band pyrometer. Multi-band pyrometer has many advantages: it can hardly be affected by the emission of measured surface and the environment radiation, and it has higher Signal-to-Noise Ratio and higher temperature measurement accuracy. This paper introduces the principle of a multi-band pyrometer and the uncertainty of measurement result is evaluated by using Monte-Carlo Method (MCM). The result shows that the accuracy of effective wavelength is the largest source of uncertainty and the other main source is reference temperature. When using ordinary blackbody furnace with continuous temperature, which can provide reference temperature and calibrate effective wavelength, the uncertainty component is 2.17K and 2.48K respectively. The combined standard uncertainty is 3.30K. A new calibration method is introduced. The effective wavelength is calibrated by monochromator, and the reference temperature is provided by fixed point black body furnace. The uncertainty component is decreased to 0.73K and 0.12K respectively. The measurement uncertainty is decreased to 0.74K. The temperature measurement accuracy is enhanced.

Yang, Yongjun; Zhang, Xuecong; Cai, Jing; Wang, Zhongyu

2010-12-01

22

A Self Calibrating Emissivity and/or Transmissivity Independent Multiwavelength Pyrometer  

NASA Technical Reports Server (NTRS)

Pyrometer is a favorite method to do remote temperature measurement in research and development. One-color, two-color and the disappearing filament pyrometers are most common, multicolor and multiwavelength pyrometers are being introduced recently. All these pyrometers invariably require, in one form or another, information concerning emissivity, the medium transmissivity, their ratio at some two spectral regions, the instrument's calibration constant, etc. for their operation. This information can come from hand books, from the manufacturer or in some instances, from results of dedicated separate experiments. Often this information is sample or instrument specific. Sometimes this information, though obtained from a special experiment, is obtained using a separate sample rather than the one pursued for temperature measurement. Then, there would be the question of variability from sample to sample and variability from batch to batch in the sample used. Also, previously determined calibrations can change with time, and the only way to reduce uncertainty is to perform the calibration more frequently or even immediately before the experiment. We have developed a multiwavelength pyrometer, which eliminates the need to supply the necessary emissivity and/or transmissivity information and the instrument calibration constants ahead of time. The pyrometer calibrates itself from its first cycle data.

Ng, Daniel

1996-01-01

23

Design of a pyrometer for temperature measurements on the solid fuel combustion chamber  

NASA Astrophysics Data System (ADS)

A pyrometer was developed for the measurement of the flame temperature of the solid fuel combustion chamber. The principle of the design is based on the measurement of the spectral intensity at two wavelengths, 577 and 830 nm, emitted by the soot in the flame. The ratio of the intensities is a univocal measure of the color temperature at these wavelengths. The apparatus is small, robust and user friendly. Calibration currents which imitate the output of the detectors are used to control the electronic circuits. The preliminary measuring accuracy between 1400 and 2800 K is about 20 K if the pyrometer is calibrated every 4 months using a qualified tungsten ribbon lamp.

Aarts, W. J. A. M.; Wijchers, T.

1987-10-01

24

Design of a pyrometer for temperature measurements on the solid fuel combustion chamber  

Microsoft Academic Search

A pyrometer was developed for the measurement of the flame temperature of the solid fuel combustion chamber. The principle of the design is based on the measurement of the spectral intensity at two wavelengths, 577 and 830 nm, emitted by the soot in the flame. The ratio of the intensities is a univocal measure of the color temperature at these

W. J. A. M. Aarts; T. Wijchers

1987-01-01

25

Temperature Measurement of a Glass Material Using a Multiwavelength Pyrometer  

NASA Technical Reports Server (NTRS)

Temperature measurement of a substance that is transparent using the traditional 1-color, 2-color and other pyrometers has been difficult. The radiation detected by pyrometers do not come from a well defined location in the transparent body. The multiwavelength pyrometer developed at the NASA Lewis Research Center can measure the surface temperature of many materials. We show in this paper that it also measures the surface and a bulk subsurface temperature of transparent materials like glass.

Ng, Daniel

1997-01-01

26

The Development and Characterization of an Absolute Pyrometer Calibrated for Radiance Responsivity  

NASA Astrophysics Data System (ADS)

For temperatures above the freezing temperature of silver, the International Temperature Scale of 1990 (ITS-90) is defined in terms of spectral radiance ratios to one of the silver, gold or copper freezing-temperature blackbodies using the Planck radiance law. However, due to the use of spectral radiance ratios, the uncertainties in the realization of thermodynamic temperatures using ITS-90 increase as the square of the temperature ratios. Such increases in the temperature uncertainties can be reduced by using absolute radiometry with pyrometers traceable to cryogenic radiometers, and the resulting temperature uncertainties can be smaller than those measured using the ratio pyrometry as prescribed in ITS-90. We describe the development and the characterization of an absolute pyrometer (AP1) constructed at NIST and calibrated for absolute radiance responsivity. The calibrations are performed with the pyrometer as a single unit; thus separate measurements of the lens transmittance and the spectral responsivities of the filters and detector are not required. The temperature measurement capabilities of the AP1 are shown using the melt and freeze cycle of the gold-point blackbody.

Allen, David W.; Saunders, Robert D.; Johnson, B. Carol; Gibson, Charles E.; Yoon, Howard W.

2003-09-01

27

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

NASA Astrophysics Data System (ADS)

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

2014-02-01

28

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

29

On the Use of the N.P.L. Photoelectric Pyrometer to Establish the Temperature Scale Above the Gold Point (1063 ^circC)  

Microsoft Academic Search

The design and performance of the N.P.L. photoelectric pyrometer is described together with its use in the realization of the International Practical Temperature Scale over the range 1063 to 2700^circC. The photoelectric pyrometer operated on the substitution principle having as an external reference source a black-body lamp. The effective wavelength of the system was defined by an interference filter having

T. J. Quinn; M. C. Ford

1969-01-01

30

Multicolor pyrometer for materials processing in space, phase 2  

NASA Technical Reports Server (NTRS)

The program goals were to design, construct, and program a prototype passive imaging pyrometer capable of measuring, as accurately as possible, the temperature distribution across the surface of a moving object suspended in space.

Frish, Michael; Frank, Jonathan; Beerman, Henry

1988-01-01

31

The non-source temperature calibration method of multi-spectral pyrometer  

NASA Astrophysics Data System (ADS)

At present, Multi-spectral pyrometer (MSP) used in high-temperature measurement has already had high resolution and high signal to noise ratio. However, the non-source temperature (higher than 3000°C) calibration falls far behind the development of MSP and has already seriously hindered the precision and application range of the pyrometer. In order to break through the limitation of calibration of non-source temperature, a new calibration method has been put forward in this paper. The temperature-voltage (T-U) model is formed based on power function where output voltage U of the MSP is derived from its corresponding known temperature point. Based on the model, Derivative least square method is used to obtain the parameters of the model to realize the non-source temperature calibration. Both theoretical and experimental data have proved the efficiency and precision of the calibration method. In addition, within the spectral range of high-temperature measurement pyrometer (0.4um~1.1um), the theoretical aberration within 1800°C extrapolation range is less than 13.54°C.

Sun, Kun; Sun, Xiaogang; Dai, Jingmin; Wang, Li

2011-11-01

32

Temperature measurement of ratio pyrometers of melting pool surfaces  

Microsoft Academic Search

The errors in measurement employing quotient pyrometry are a function of the temperature and the effective wavelengths used. They are generated by the spectral emission coefficients of the surface of the test specimen and the spectral transmissivity of the media in the beam path. Temperature-independent deviations up to -30°K have been found for various imaging lenses using calibrated tungsten strip

Mack

1978-01-01

33

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

34

A high-speed four-channel infrared pyrometer  

SciTech Connect

A high-speed, four-wavelength pyrometer has been developed for dynamic temperature measurements on samples that are heated by shock compression. The pyrometer uses a pair of off-axis parabolic mirrors to collect radiance emitted from a target of 1 mm in diameter. A single optical fiber delivers the collected radiant flux to the detector housing. Three dichroic beam splitters are used to spectrally split the light into four beams that are then focused onto an equal number of LN2-cooled InSb photodetectors. Broad bandwidth interference filters that are nominally centered at 1.8, 2.4, 3.4, and 5.0 {micro}m define the wavelength ranges of the four channels. The blackbody-temperature threshold of the pyrometer is at about 400 K. The signals are recorded at intervals as short as 20 ns using a four-channel digital oscilloscope. Procedures for calibration and temperature measurements are described.

Boboridis, K.; Obst, A. W. (Andrew W.)

2002-01-01

35

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

36

Imaging pyrometer for monitoring the surface temperature of a spray-formed steel billet  

NASA Astrophysics Data System (ADS)

A two-wavelength, imaging pyrometer was developed for real- time measurement of the surface temperature distribution of a spray-formed steel billet. This new spray-forming process is used to deposit bulk steel on a ceramic substrate in a surface temperature range of 300 degrees C to 400 degrees C, using four, twin-wire arc plasma torches. These steel billets are used as tools in metal forming processes, injection molding and die casting tools, and other processes that may need hard tooling, such as the automotive industry. The steel billet must be formed with a uniform, surface temperature distribution to minimize the thermal stresses within the steel, throughout the process. The imaging pyrometer uses a near-IR InGaAs CCD camera with high quantum efficiency from 0.95 to 1.75 microns. The wavelengths of 1.40 and 1.65 microns were selected to sense the low temperature billet. The camera has a format of 320 x 240 pixels with a pixel spacing of 30 microns and an integral 12-bit A/D converter with both video and digital outputs. The design of the pyrometer provides a working distance of 2.2 meters and a field of view of 0.6 meters. This technical paper describes the calibrations and initial measurement results obtained in a spray forming facility at the Ford Research Laboratory. The calibration provided intensity ratio measurements for surface temperatures ranging from 200 degrees C to 300 degrees C, the expected range of operation. The initial measurements described here depict the surface temperature distribution of the steel billet throughout the spray forming process, typically lasting several hours.

Parker, Ronald A.; Allor, Richard

2001-03-01

37

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

38

Application of the Self Calibrating Emissivity and/or Transmissivity Independent Multiwavelength Pyrometer in an Intense Ambient Radiation Environment  

NASA Technical Reports Server (NTRS)

The NASA self calibrating multiwavelength pyrometer is a recent addition to the list of pyrometers used in remote temperature measurement in research and development. The older one-color, two-color, and the disappearing filament pyrometers, as well as the multicolor and early multiwavelength pyrometers, all do not operate successfully in situations in which strong ambient radiation coexists with radiation originating from the measured surface. In such situations radiation departing from the target surface arrives at the pyrometer together with radiation coming from another source either directly or through reflection. Unlike the other pyrometers, the self calibrating multiwavelength pyrometer can still calibrate itself and measure the temperatures in this adverse environment.

Ng, Daniel

1996-01-01

39

Radiation temperature measurement method for semitransparent materials using one-channel infrared pyrometer.  

PubMed

Semitransparent zinc sulfide (ZnS) crystal materials are widely used as the infrared-transmitting windows for optical instruments operating in long wavelengths. This paper describes a temperature measurement method for high-temperature ZnS materials using the one-channel optical pyrometer based on a theoretical model of radiation transfer in semitransparent plates. Numerical analyses of the radiation properties of ZnS plate are used to optimize the spectral band for the optical pyrometry. The optimized measurement spectral band is based on a trade-off between the measurement radiation intensity and the signal-to-noise ratio (SNR) for the ZnS material. The effective waveband emittance of one-dimensional (1D) ZnS plates is analyzed for various experimental conditions (temperatures, thicknesses, and direction angles) for the one-channel infrared pyrometer with the optimized measurement spectral response. The analysis can be used to improve radiation temperature measurements of semitransparent ZnS materials in applications. PMID:25322390

Fu, Tairan; Liu, Jiangfan; Zong, Anzhou

2014-10-10

40

Multi-color pyrometer for materials processing in space  

NASA Technical Reports Server (NTRS)

The design, construction and calibration of a computer-linked multicolor pyrometer is described. The device was constructed for ready adaptation to a spacecraft and for use in the control of thermal processes for manufacturing materials in space. The pyrometer actually uses only one color at a time, and is relatively insensitive to uncertainties in the heated object's emissivity because the product of the color and the temperature has been selected to be within a regime where the radiant energy emitted from the body increases very rapidly with temperature. The instrument was calibrated and shown to exceed its design goal of temperature measurements between 300 and 2000 C, and its accuracy in the face of imprecise knowledge of the hot object's emissivity was demonstrated.

Frish, Michael B.; Spencer, Mark N.; Wolk, Nancy E.; Werner, Jennifer S.; Miranda, Henry A., Jr.

1988-01-01

41

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

42

Air-fuel ratio feedback control system  

SciTech Connect

An air-fuel ratio feedback control system for the internal combustion engine produces a fuel supply control signal by delaying a rich or lean signal obtained by comparing the oxygen concentration in the exhaust gas with a reference value. The turning on of an idle switch operatively connected with the engine throttle valve, a predetermined time after the turning off of the idle switch and the engine speed included in a predetermined region are detected in order to delay the rich or lean signal to rich or lean side by an optimum delay time as selected according to the engine operating conditions, thus feedback controlling the amount of fuel supply.

Yoshida, S.; Hoshi, K.; Matsuo, M.; Ono, H.; Sueishi, M.; Ueda, K.

1984-01-17

43

Combustion gas temperature in a prechamber spark ignition engine measured by infrared pyrometer  

SciTech Connect

To obtain a more reasonable model of torch combustion in a spark ignition engine with a vertical or horizontal prechamber, the instantaneous temperatures of combustion gas are measured by an infrared absorption-emission pyrometer with a narrow band pass filter for CO/sub 2/ gas, while changing the torch nozzle area and air-fuel ratio. The gas temperature diagrams indicate that the ignition timing, flame propagation and combustion duration in the main chamber with vertical prechamber differ entirely from those with horizontal one. The fact is verified by comparing them with the heat release rates obtained from the pressure diagrams and with the flame propagation taken by means of high-speed photography. The measured gas temperature diagrams are, therefore, found to provide a lot of useful and local information concerning the combustion process and the engine performance in the prechamber engines.

Sakurauchi, Y.; Ryu, H.; Iijima, T.; Asanuma, T.

1987-01-01

44

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

45

Use of a multiwavelength pyrometer in several elevated temperature aerospace applications  

NASA Astrophysics Data System (ADS)

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 zircornia 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

2001-02-01

46

Design and Construction of a New Primary Standard Pyrometer at NPL  

Microsoft Academic Search

For many years the temperature scale at NPL has been realized and maintained using the NPL primary pyrometer. This instrument has reached the end of its useful life, and a replacement instrument has been built and is currently being validated. This new instrument will give reduced uncertainties in disseminating the temperature scale. The new pyrometer uses lens optics, designed to

D. Lowe; H. C. McEvoy; G. Machin

2003-01-01

47

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

48

Infrared temperature measurement with self regulating emission ratio  

Microsoft Academic Search

A temperature measuring procedure without contact, based on infrared radiation pyrometers is described. A self-regulating emission ratio multispectral pyrometer able to register three parameters related to the spectral composition of a non-black object: object temperature, emission ratio, and object environmental temperature was developed. Self-calibrating factors depending on wavelength via computer program simulation are described. Commercial infrared detector components are investigated

V. Tank

1987-01-01

49

Infrared temperature measurement with self regulating emission ratio  

NASA Astrophysics Data System (ADS)

A temperature measuring procedure without contact, based on infrared radiation pyrometers is described. A self-regulating emission ratio multispectral pyrometer able to register three parameters related to the spectral composition of a non-black object: object temperature, emission ratio, and object environmental temperature was developed. Self-calibrating factors depending on wavelength via computer program simulation are described. Commercial infrared detector components are investigated for their adaptability to requirements.

Tank, V.

50

Ratios  

NSDL National Science Digital Library

This set of instructional materials and problems helps students understand ratios and proportions, starting with a simple review and progressing into the more advanced territory of similar triangles. The first three pages introduce ratios, proportions, and checking proportionality and the last four pages present mathematical and real-world problems for students to solve given their understanding of ratios and proportions.

Stapel, Elizabeth

2000-01-01

51

Multiwavelength optical pyrometer for shock compression experiments.  

PubMed

A system for measurement of the spectral radiance of materials shocked to high pressures ( approximately 100 GPa) by impact using a light gas gun is described. Thermal radiation from the sample is sampled at six wavelength bands in the visible spectrum, and each signal is separately detected by solid-state photodiodes, and recorded with a time resolution of approximately 10 ns. Interpretation of the records in terms of temperature of transparent sample materials is discussed. Results of a series of exploratory experiments with metals are also given. Shock temperatures in the range 4000-8000 K have been reliably measured. Spectral radiance and temperatures have been determined with uncertainties of 2%. PMID:18699402

Lyzenga, G A; Ahrens, T J

1979-11-01

52

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

53

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

54

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

SciTech Connect

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 highspeed infrared pyrometry in shock physics experiments.

J.A. Young, S. Borrora, A.W. Obst, J.R. Payton, A. Seifter

2005-01-01

55

Elevated sacroilac joint uptake ratios in systemic lupus erythematosus  

SciTech Connect

Sacroiliac joint radiographs and radionuclide sacroiliac joint uptake ratios were obtained on 14 patients with active systemic lupus erythematosus. Elevated joint ratios were found unilaterally in two patients and bilaterally in seven patients when their lupus was active. In patients whose disease became quiescent, the uptake ratios returned to normal. Two patients had persistently elevated ratios with continued clinical and laboratory evidence of active lupus. Mild sacroiliac joint sclerosis and erosions were detected on pelvic radiographs in these same two patients. Elevated quantitative sacroiliac joint uptake ratios may occur as a manifestation of active systemic lupus erythematosus.

De Smet, A.A.; Mahmood, T.; Robinson, R.G.; Lindsley, H.B.

1984-08-01

56

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

57

Variance of the Strehl ratio of an adaptive optics system  

Microsoft Academic Search

The variance sigmaS2 of the Strehl ratio of a reasonably well-corrected adaptive optics system is derived as a power series in the log-amplitude variance sigmal2 and the residual phase error variance sigmadeltaphi2. It is shown that, to leading order, the variance of the Strehl ratio is dependent on the first power of the log-amplitude variance, (sigmal2)1, of the incident optical

H. T. Yura; D. L. Fried

1998-01-01

58

Alternative calibration techniques for high-speed pyrometers in shock experiments  

Microsoft Academic Search

Optical pyrometry is widely used in industry and research laboratories to perform surface temperature measurements of sample materials. These shock physics experiments are normally conducted at powder or gas gun facilities or at facilities where high explosives can be used as a shock wave source, and using high-speed pyrometers that are usually calibrated by using a blackbody source. But, electrical

D. Partouche-Sebban; D. B. Holtkamp; P. Rodriguez; J. B. Stone; S. D. Borror; C. A. Kruschwitz; J. A. Young

2005-01-01

59

A cooled-gas pyrometer for use in hypersonic engine testing  

NASA Technical Reports Server (NTRS)

A cooled-gas pyrometer designed for application in a hypersonic research engine program was fabricated and tested. Design and operational considerations and calibration data are presented. The probe was tested in a rocket-engine exhaust stream operating at Mach 2 and 2300 K. Test temperature measurements agreed to within 2 percent with a radiation shielded thermocouple probe.

Glawe, G. E.

1973-01-01

60

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

61

Development of a CO?b2?s laser-based system for characterization of high-temperature structural ceramics  

E-print Network

just as easily change the object's distance from the pyrometer). This is due to the fact that the pyrometer has fixed-focus optical elements, giving it a fixed distance-to-spot-size ratio, The minimum measurement spot is a circular spot of diameter 3... just as easily change the object's distance from the pyrometer). This is due to the fact that the pyrometer has fixed-focus optical elements, giving it a fixed distance-to-spot-size ratio, The minimum measurement spot is a circular spot of diameter 3...

Bowman, David Winslow

2012-06-07

62

The period ratio distribution of Kepler's candidate multiplanet systems  

E-print Network

We calculate and analyze 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 (MMR), 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---sys...

Steffen, Jason H

2014-01-01

63

High ratio long-wave infrared continuous zoom system  

NASA Astrophysics Data System (ADS)

As infrared zoom systems change the focal length continuously, remain images stability and keep good image quality during the process of zoom, it is widely applied to infrared navigation, infrared detection, infrared-guided etc vehicular and airborne area. In order to satisfy the growing demand of infrared continuous zoom system, a zoom ratio of ten times long-wave infrared continuous zoom optical system that based on an uncooled detector was designed. System guided by the zoom theory of positive groups of compensation, calculated the initial structure of the system and according to the system of optical parameters with using ZEMAX software for optical design did an aberration balance and optimized, then the optical system image quality was systematically analyzed and evaluated. The result showed that the modulation transfer function (MTF) was above 0.4 within the whole focal range at spatial frequency 16 lp/mm, the root mean square radius of maximum dispersion spot was smaller than a pixel dimension and it met the requirements of the system imaging quality when F/# was 2, continuous zoom range was from 40 mm to 400 mm and the image size was 12 mm. The design of the system realized the requirements of compact structure, large zoom ratio, easily assembled and excellent image quality to optical system for infrared imaging.

Yan, Jing; Sun, Quan; Liu, Ying; Zhou, Hao; Huan, Kewei; Shi, Xiao-guang

2013-09-01

64

Calibration of an intensity ratio system for 3D imaging  

NASA Astrophysics Data System (ADS)

An intensity ratio method for 3D imaging is proposed with error analysis given for assessment and future improvements. The method is cheap and reasonably fast as it requires no mechanical scanning or laborious correspondence computation. One drawback of the intensity ratio methods which hamper their widespread use is the undesirable change of image intensity. This is usually caused by the difference in reflection from different parts of an object surface and the automatic iris or gain control of the camera. In our method, gray-level patterns used include an uniform pattern, a staircase pattern and a sawtooth pattern to make the system more robust against errors in intensity ratio. 3D information of the surface points of an object can be derived from the intensity ratios of the images by triangulation. A reference back plane is put behind the object to monitor the change in image intensity. Errors due to camera calibration, projector calibration, variations in intensity, imperfection of the slides etc. are analyzed. Early experiments of the system using a newvicon CCTV camera with back plane intensity correction gives a mean-square range error of about 0.5 percent. Extensive analysis of various errors is expected to yield methods for improving the accuracy.

Tsui, H. T.; Tang, K. C.

1989-03-01

65

A high-speed spatial (linear) scanning pyrometer: A tool for diagnostics, temperature mapping, and property determinations at high temperatures  

NASA Technical Reports Server (NTRS)

Development of a fast spatial scanning pyrometer for temperature measurements above 1500 K is described. The salient features of the pyrometer are: (1) it measures spectral radiance temperature (at 0.65 micron) at 1024 points along a straight line (25 mm long) on the target; (2) it has no moving parts and uses a self-scanning linear array of silicon photodiodes as the detector; (3) its output is recorded digitally every 1 microsec with a full-scale resolution of about 1 part in 4000, permitting performance of a complete cycle of measurements (1024 points) in about 1 ms. Operational characteristics of the pyrometer are given. Examples of measurements of the temperature along rapidly heated (resistive self-heating) specimens (rod, tube, strip) are presented. Potential use of the pyrometer in the experiments, both ground-based and in microgravity, requiring temperature mapping and property distribution of the specimen at high temperatures is discussed.

Cezairliyan, A.; Chang, R. F.; Foley, G. M.

1990-01-01

66

A urinary metabolite ratio that reflects systemic caffeine clearance  

Microsoft Academic Search

Systemic caffeine clearance and urinary metabolite profiles were determined in 15 subjects with diverse exposure histories to cytochrome P-450 inducers (cigarette smoke) and inhibitors (oral contraceptive steroids). A correlation was observed between caffeine clearance and a urinary ratio based on the molar recovery of paraxanthine 7-demethylation products relative to a paraxanthine 8-hydroxylation product (r = 0.91; P < 0.001). Analysis

Monica E Campbell; Stephen P Spielberg; Werner Kalow

1987-01-01

67

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

68

Imaging pyrometer for monitoring the surface temperature of a spray-formed steel billet  

Microsoft Academic Search

A two-wavelength, imaging pyrometer was developed for real- time measurement of the surface temperature distribution of a spray-formed steel billet. This new spray-forming process is used to deposit bulk steel on a ceramic substrate in a surface temperature range of 300 degrees C to 400 degrees C, using four, twin-wire arc plasma torches. These steel billets are used as tools

Ronald A. Parker; Richard Allor

2001-01-01

69

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

70

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

71

Scanning optical pyrometer for measuring temperatures in hollow cathodes  

Microsoft Academic Search

Life-limiting processes in hollow cathodes are determined largely by the temperature of the electron emitter. To support cathode life assessment, a noncontact temperature measurement technique which employs a stepper motor-driven fiber optic probe was developed. The probe is driven inside the hollow cathode and collects light radiated by the hot interior surface of the emitter. Ratio pyrometry is used to

J. E. Polk; C. M. Marrese-Reading; B. Thornber; L. Dang; L. K. Johnson; I. Katz

2007-01-01

72

Radiation pyrometer for gas turbine blades. [in LOX turbopump engine  

NASA Technical Reports Server (NTRS)

A turbine blade temperature measuring system for liquid oxygen turbopumps is reported. The system includes a three mode, two-input optical signal processor, interconnecting cable, and four sensor heads. Two of the heads are aperture type, while the other two are lens type. This system is applicable to a temperature range of 1400 to 2200 F.

Rohy, D. A.; Compton, W. A.

1973-01-01

73

Temperature measurement system for optical-fiber preform fabrication  

Microsoft Academic Search

A system has been developed to measure the temperature profile across the growing surface of a soot preform in an axial vapor deposition process for optical-fiber preform fabrication. The system assembled at a fraction of the cost of commercially available instrumentation, makes use of an infrared pyrometer driven by a computer-controlled stepping motor. The pyrometer used has a temperature range

G. E. Bodeep

1984-01-01

74

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

75

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

76

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

77

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

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1455 Lecithin/sphingomyelin ratio in amniotic fluid test...

2013-04-01

78

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

Code of Federal Regulations, 2011 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1455 Lecithin/sphingomyelin ratio in amniotic fluid test...

2011-04-01

79

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

Code of Federal Regulations, 2012 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1455 Lecithin/sphingomyelin ratio in amniotic fluid test...

2012-04-01

80

Measuring mass-to-light ratios of spherical stellar systems by core fitting  

Microsoft Academic Search

The authors discuss the determination of mass-to-light ratios of spherical stellar systems by core fitting (King's method). They justify the core-fitting formula and state the conditions for its validity.

D. O. Richstone; S. Tremaine

1986-01-01

81

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

82

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

83

A high S/N ratio spin flip chopper system for a pulsed neutron source  

NASA Astrophysics Data System (ADS)

We report a successful demonstration of a high S/N ratio spin flip chopper (SFC) system for pulsed neutron sources. The system consists of two SFCs and each SFC consists of a radio frequency (RF) flipper and Soller magnetic supermirrors. The aperture of the Soller mirror was 18 mm in width and 20 mm in height. The S/N ratio of the system was 306:1. This system is going to be installed to measure neutron lifetime precisely using the cold-neutron beam line, BL05 polarized-beam branch, at the Materials and Life Science Experimental Facility (MLF) in Japan Proton Accelerator Research Complex (J-PARC).

Taketani, K.; Ebisawa, T.; Hino, M.; Hirota, K.; Ino, T.; Kitaguchi, M.; Mishima, K.; Muto, S.; Oide, H.; Oku, T.; Otono, H.; Sakai, K.; Shima, T.; Shimizu, H. M.; Yamashita, S.; Yoshioka, T.

2011-04-01

84

The solar load ratio method applied to commercial building active solar system sizing  

Microsoft Academic Search

The solar load ratio (SLR) design method was extended to commercial building combined active space heating and building service hot water (BSHW) systems and BSHW systems alone. Both liquid and air heating systems are considered. The hour-by-hour computer simulations used to calculate system performance were carried out using the component-based simulator in the DOE-2 building energy analysis computer program. Hourly

N. M. Schnurr; B. D. Hunn; K. D. Williamson III

1981-01-01

85

Differential pressure, bypass chilled water systems: Capacity ratios between on-off and modulating units  

Microsoft Academic Search

An analysis is presented concerning the relative proportion betwen the sums of rated capacities of on-off controlled and modulating controlled terminal units in differential-pressure-bypass type chilled water distribution systems. In these systems, there is the chance that differential temperature across the supply and return mains at system part-load conditions could be lower than the system design value. The ratio of

K. K. Lau

1996-01-01

86

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

87

Zernike representation and Strehl ratio of optical systems with variable numerical aperture  

Microsoft Academic Search

We consider optical systems with variable numerical aperture (NA) on the level of the Zernike coefficients of the correspondingly scalable pupil function. We thus present formulas for the Zernike coefficients and their first two derivatives as a function of the scaling factor ? ? 1, and we apply this to the Strehl ratio and its derivatives of NA-reduced optical systems.

A. J. E. M. Janssen; S. van Haver; P. Dirksen; J. J. M. Braat

2008-01-01

88

Resolving power and encircled energy in aberrated optical systems with filters optimized for the Strehl ratio  

Microsoft Academic Search

Results of the optimization of the axial response of optical systems by filters of non-uniform transmission are presented. Optical systems with different types of residual aberrations are studied. The image quality criterion considered in the optimization procedure is the Strehl Ratio (SR). The effect of these filters on the point spread function (PSF), the resolving power and the encircled energy

J. Campos; F. Calvo; M. J. Yzuel

1988-01-01

89

Application of Taguchi methods to dual mixture ratio propulsion system optimization for SSTO vehicles  

NASA Technical Reports Server (NTRS)

The application of advanced technologies to future launch vehicle designs would allow the introduction of a rocket-powered, single-stage-to-orbit (SSTO) launch system early in the next century. For a selected SSTO concept, a dual mixture ratio, staged combustion cycle engine that employs a number of innovative technologies was selected as the baseline propulsion system. A series of parametric trade studies are presented to optimize both a dual mixture ratio engine and a single mixture ratio engine of similar design and technology level. The effect of varying lift-off thrust-to-weight ratio, engine mode transition Mach number, mixture ratios, area ratios, and chamber pressure values on overall vehicle weight is examined. The sensitivity of the advanced SSTO vehicle to variations in each of these parameters is presented, taking into account the interaction of each of the parameters with each other. This parametric optimization and sensitivity study employs a Taguchi design method. The Taguchi method is an efficient approach for determining near-optimum design parameters using orthogonal matrices from design of experiments (DOE) theory. Using orthogonal matrices significantly reduces the number of experimental configurations to be studied. The effectiveness and limitations of the Taguchi method for propulsion/vehicle optimization studies as compared to traditional single-variable parametric trade studies is also discussed.

Stanley, Douglas O.; Unal, Resit; Joyner, C. R.

1992-01-01

90

DISK-PLANETS INTERACTIONS AND THE DIVERSITY OF PERIOD RATIOS IN KEPLER'S MULTI-PLANETARY SYSTEMS  

SciTech Connect

The Kepler mission is dramatically increasing the number of planets known in multi-planetary systems. Many adjacent planets have orbital period ratios near resonant values, with a tendency to be larger than required for exact first-order mean-motion resonances. This feature has been shown to be a natural outcome of orbital circularization of resonant planetary pairs due to star-planet tidal interactions. However, this feature holds in multi-planetary systems with periods longer than 10 days, in which tidal circularization is unlikely to provide efficient divergent evolution of the planets' orbits to explain these orbital period ratios. Gravitational interactions between planets and their parent protoplanetary disk may instead provide efficient divergent evolution. For a planet pair embedded in a disk, we show that interactions between a planet and the wake of its companion can reverse convergent migration and significantly increase the period ratio from a near-resonant value. Divergent evolution due to wake-planet interactions is particularly efficient when at least one of the planets opens a partial gap around its orbit. This mechanism could help account for the diversity of period ratios in Kepler's multiple systems from super-Earth to sub-Jovian planets with periods greater than about 10 days. Diversity is also expected for pairs of planets massive enough to merge their gap. The efficiency of wake-planet interactions is then much reduced, but convergent migration may stall with a variety of period ratios depending on the density structure in the common gap. This is illustrated for the Kepler-46 system, for which we reproduce the period ratio of Kepler-46b and c.

Baruteau, Clement; Papaloizou, John C. B., E-mail: C.Baruteau@damtp.cam.ac.uk, E-mail: J.C.B.Papaloizou@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

2013-11-20

91

Disk-Planets Interactions and the Diversity of Period Ratios in Kepler's Multi-planetary Systems  

NASA Astrophysics Data System (ADS)

The Kepler mission is dramatically increasing the number of planets known in multi-planetary systems. Many adjacent planets have orbital period ratios near resonant values, with a tendency to be larger than required for exact first-order mean-motion resonances. This feature has been shown to be a natural outcome of orbital circularization of resonant planetary pairs due to star-planet tidal interactions. However, this feature holds in multi-planetary systems with periods longer than 10 days, in which tidal circularization is unlikely to provide efficient divergent evolution of the planets' orbits to explain these orbital period ratios. Gravitational interactions between planets and their parent protoplanetary disk may instead provide efficient divergent evolution. For a planet pair embedded in a disk, we show that interactions between a planet and the wake of its companion can reverse convergent migration and significantly increase the period ratio from a near-resonant value. Divergent evolution due to wake-planet interactions is particularly efficient when at least one of the planets opens a partial gap around its orbit. This mechanism could help account for the diversity of period ratios in Kepler's multiple systems from super-Earth to sub-Jovian planets with periods greater than about 10 days. Diversity is also expected for pairs of planets massive enough to merge their gap. The efficiency of wake-planet interactions is then much reduced, but convergent migration may stall with a variety of period ratios depending on the density structure in the common gap. This is illustrated for the Kepler-46 system, for which we reproduce the period ratio of Kepler-46b and c.

Baruteau, Clement; Papaloizou, John C. B.

2013-11-01

92

Effects of feedstock, airflow rate, and recirculation ratio on performance of composting systems with air recirculation.  

PubMed

The thermodynamics, kinetics, and energy use of composting systems with air recirculation were determined for feedstocks comprising paper mill sludge and biosolids. Results were developed by simulating the composting system using a two-dimensional finite difference numerical model. Incorporated into the simulation model was independent regulation of temperature and oxygen using a closed loop feedback control system with a two-stage fan setting. Results showed that at low airflows and high recirculation ratios, heat removal by the exhaust gas was insufficient to maintain set point temperatures with the result that process temperatures increased and eventually limited the reaction rate. Types of feedstock, magnitude of airflow and recirculation ratio all affected the energy use of the system. Although recirculation leads to high energy use, it can produce high quality compost by having a temperature gradient of less than 2 degrees C across the bed. PMID:15963715

Ekinci, K; Keener, H M; Akbolat, D

2006-05-01

93

Application of Taguchi methods to dual mixture ratio propulsion system optimization for SSTO vehicles  

Microsoft Academic Search

The application of advanced technologies to future launch vehicle designs would allow the introduction of a rocket-powered, single-stage-to-orbit (SSTO) launch system early in the next century. For a selected SSTO concept, a dual mixture ratio, staged combustion cycle engine that employs a number of innovative technologies was selected as the baseline propulsion system. A series of parametric trade studies are

Douglas O. Stanley; Resit Unal; C. R. Joyner

1992-01-01

94

The effects of R/X ratios on power system minimum loss  

E-print Network

. It has been found that, if the R/X ratio of all lines are constant, minimum I R lo ss will occur when all gener- ator busses are at the same augie' If these rat1os are oonstant, the use of the magnitude of 2 to obtain the division of ourrents would... to investigate the effect of var- iations of R/X ratios on the application of the equal angle theory, as no power system exists in which these factors are constant. It is apparent that this invustigation will g1ve some- what different results, depending upon...

Denison, John Scott

2012-06-07

95

An acoustic pyrometer system for tomographic thermal imaging in power plant boilers  

Microsoft Academic Search

The paper presents an acoustic pyrometry method for the reconstruction of temperature maps inside power plant boilers. It is based on measuring times-of-flight of acoustic waves along a number of straight paths in a cross-section of the boiler; via an integral relationship, these times depend on the temperature of the gaseous medium along the paths. On this basis, 2D temperature

Mauro Bramanti; Emanuele A. Salerno; Anna Tonazzini; Sauro Pasini; Antonio Gray

1996-01-01

96

Competitive Ratio Analysis of Online Algorithms to Minimize Data Transmission Time in Energy Harvesting Communication System  

E-print Network

We consider the optimal online packet scheduling problem in a single-user energy harvesting wireless communication system, where energy is harvested from natural renewable sources, making future energy arrivals instants and amounts random in nature. The most general case of arbitrary energy arrivals is considered where neither the future energy arrival instants or amount, nor their distribution is known. The problem considered is to adaptively change the transmission rate according to the causal energy arrival information, such that the time by which all packets are delivered is minimized. We assume that all bits have arrived and are ready at the source before the transmission begins. For a minimization problem, the utility of an online algorithm is tested by finding its competitive ratio or competitiveness that is defined to be the maximum of the ratio of the gain of the online algorithm with the optimal offline algorithm over all input sequences. We derive a lower and upper bound on the competitive ratio of...

Vaze, Rahul

2011-01-01

97

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

2014-10-01

98

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

99

Pyrometer for measurement of surface temperature distribution on a rotating turbine blade  

NASA Technical Reports Server (NTRS)

A conceptual optical method and some test results are presented for measuring the surface temperature distribution on one of the rotating turbine blades with a surface resolution of 0.05 cm spot diameter at a tip speed of 400 m/sec. The blade is scanned line-by-line by a fixed optical system. During each line-scan, the detector analog output signal is converted to two hundred consecutive digital values that are temporarily stored in a high speed buffer memory, and then transferred at a slower rate to a computer for processing. The signal-to-noise ratio of the silicon avalanche detector is large enough to obtain an accuracy of one percent at 1050 K blade temperature. By averaging 25 scans of the same line the same accuracy can be obtained at 900 K.

Buchele, D. R.; Lesco, D. J.

1972-01-01

100

A genetic perspective on mating systems and sex ratios of parasitoid wasps  

Microsoft Academic Search

Parasitoid sex ratios are influenced by mating systems, whether complete inbreeding, partial inbreeding, complete inbreeding\\u000a avoidance, or production of all-male broods by unmated females. Population genetic theory demonstrates that inbreeding is\\u000a possible in haplodiploids because the purging of deleterious and lethal mutations through haploid males reduces inbreeding\\u000a depression. However, this purging does not act quickly for deleterious mutations or female-limited

Michael F. Antolin

1999-01-01

101

Dependence of Strehl ratio on f-number of optical system.  

PubMed

Formulas for a minimum of wave aberration variance and a maximum of the Strehl ratio in the optimal image point are derived using the third- and fifth-order aberration theory. Moreover, relations for the calculation of the optimal value of f-number of the optical system were derived, which enabled us to theoretically analyze real optical systems and their image quality. The optimal f-number corresponds to such a value of f-number when the image quality of a real optical system is comparable to an aberration-free optical system. This value may also serve as an auxiliary criterion of the image quality of the optical system, for example, in photography. PMID:22695658

Miks, Antonin; Novak, Jiri; Novak, Pavel

2012-06-10

102

Branching ratio measurement of a ? system in Tm3+:YAG under a magnetic field  

NASA Astrophysics Data System (ADS)

A three-level ? system in Tm3+ doped YAG crystal is experimentally investigated in the prospect of quantum information processing. Zeeman effect is used to lift the nuclear spin degeneracy of this ion. In a previous paper [de Seze , Phys. Rev. B 73, 085112 (2006)] we measured the gyromagnetic tensor components and concluded that adequate magnetic field orientation could optimize the optical connection of both ground state sublevels to each one of the excited state sublevels, thus generating ? systems. Here we report on the direct measurement of the transition probability ratio along the two legs of the ? . Measurement techniques combine frequency selective optical pumping with optical nutation or photon echo processes.

Louchet, A.; Habib, J. S.; Crozatier, V.; Lorgeré, I.; Goldfarb, F.; Bretenaker, F.; Gouët, J.-L. Le; Guillot-Noël, O.; Goldner, Ph.

2007-01-01

103

Nonaxial Strehl ratio of wavefront coding systems with a cubic phase mask.  

PubMed

An approximate expression of the peak position of the point-spread function (PSF) of wavefront coding systems with a cubic phase mask (CPM) is derived and verified by simulation results. An approach called the nonaxial Strehl ratio (NASR) is used to evaluate the performance of wavefront coding systems with defocus aberrations. The characteristics of the NASR are investigated. The relationships between the NASR and the similarity of out-of-focus modulation transfer function (MTF) and recoverability of blurred encoding images are presented, and some useful guidelines are given for the optimization of phase mask parameters according to these relationships. PMID:21743538

Chen, Shouqian; Fan, Zhigang; Chang, Hong; Xu, Zhigao

2011-07-01

104

The Minimum Mass Ratio for Contact Close Binary Systems of W Ursae Majoris-Type  

NASA Astrophysics Data System (ADS)

The main research topic of this dissertation are extreme mass ratio contact close binary systems, q ? 0.1, of W Ursae Majoris (W UMa) type. These close binaries (CBs) represent an interesting class of objects in which "normal", approximately one solar mass main-sequence star is in contact with a significantly less massive companion, M_2 ˜ 0.1 M_?. Earlier theoretical investigations of these systems found that there is a minimum mass ratio q_{min} = M_2/M_1 = 0.085 - 0.095 (obtained for n = 3 polytrope - fully radiative primary) above which these CBs are stable and could be observed. If the mass ratio is lower than q_{min}, or, equivalently, if orbital angular momentum is only about three times larger than the spin angular momentum of a massive primary, a tidal instability develops (Darwin's instability) forcing eventually the stars to merge into a single, rapidly rotating object (such as FK Com-type stars or blue stragglers). However, there appear to be some W UMa-type CBs with empirically obtained values for the mass ratio below the theoretical limit for stability. The aim of this dissertation is to try to resolve the discrepancy between theory and observations by considering rotating polytropes. By including in theory the effects of higher central condensation due to rotation we were able to reduce qmin to the new theoretical value q_{min} = 0.070-0.074, for the overcontact degree f = 0 - 1, which is more consistent with the observed population. Other candidate systems for stellar mergers such as AM CVn-type stars have also been discussed in the dissertation.

Arbutina, B.

2012-12-01

105

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

106

Double neutron/proton ratio of nucleon emissions in isotopic reaction systems as a robust probe of nuclear symmetry energy  

NASA Astrophysics Data System (ADS)

The double neutron/proton ratio of nucleon emissions taken from two reaction systems using four isotopes of the same element, namely, the neutron/proton ratio in the neutron-rich system over that in the more symmetric system, has the advantage of reducing systematically the influence of the Coulomb force and the normally poor efficiencies of detecting low energy neutrons. The double ratio thus suffers less systematic errors. Within the IBUU04 transport model the double neutron/proton ratio is shown to have about the same sensitivity to the density dependence of nuclear symmetry energy as the single neutron/proton ratio in the neutron-rich system involved. The double neutron/proton ratio is therefore more useful for further constraining the symmetry energy of neutron-rich matter.

Li, Bao-An; Chen, Lie-Wen; Yong, Gao-Chan; Zuo, Wei

2006-03-01

107

The Development and Characterization of an Absolute Pyrometer Calibrated for Radiance Responsivity  

Microsoft Academic Search

For temperatures above the freezing temperature of silver, the International Temperature Scale of 1990 (ITS-90) is defined in terms of spectral radiance ratios to one of the silver, gold or copper freezing-temperature blackbodies using the Planck radiance law. However, due to the use of spectral radiance ratios, the uncertainties in the realization of thermodynamic temperatures using ITS-90 increase as the

David W. Allen; Robert D. Saunders; B. Carol Johnson; Charles E. Gibson; Howard W. Yoon

2003-01-01

108

Spatio-temporal patterns of C : N : P ratios in the northern Benguela upwelling system  

NASA Astrophysics Data System (ADS)

On a global scale the ratio of fixed nitrogen (N) and phosphate (P) is characterized by a deficit of N with regard to the classical Redfield ratio of N : P = 16 : 1 reflecting the impact of N loss occurring in the oceanic oxygen minimum zones. The northern Benguela upwelling system (NBUS) is known for losses of N and the accumulation of P in sub- and anoxic bottom waters and sediments of the Namibian shelf resulting in low N : P ratios in the water column. To study the impact of the N : P anomalies on the regional carbon cycle and their consequences for the export of nutrients from the NBUS into the oligotrophic subtropical gyre of the South Atlantic, we measured dissolved inorganic carbon (CT), total alkalinity (AT), oxygen (O2) and nutrient concentrations in February 2011. The results indicate increased P concentrations over the Namibian shelf due to P efflux from sediments resulting in a C : N : P : -O2 ratio of 106 : 16 : 1.6 : 138. N reduction further increase C : N and reduce N : P ratios in those regions where O2 concentrations in bottom waters are < 20 ?mol kg-1. However, off the shelf along the continental margin, the mean C : N : P : -O2 ratio is again close to the Redfield stoichiometry. Additional nutrient data measured during two cruises in 2008 and 2009 imply that the amount of excess P, which is created in the bottom waters on the shelf, and its export into the subtropical gyre after upwelling varies through time. The results further reveal an inter-annual variability of excess N within the South Atlantic Central Water (SACW) that flows from the north into the NBUS, with highest N values observed in 2008. It is postulated that the N excess in SACW occurred due to the impact of remineralized organic matter produced by N2 fixation and that the magnitude of excess P formation and its export is governed by inputs of excess N along with SACW flowing into the NBUS. Factors controlling N2 fixation north of the BUS need to be addressed in future studies to better understand the role of the NBUS as a P source and N sink in the coupled C : N : P cycles.

Flohr, A.; van der Plas, A. K.; Emeis, K.-C.; Mohrholz, V.; Rixen, T.

2014-02-01

109

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

110

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

111

High Fill-Out, Extreme Mass Ratio Overcontact Binary Systems. VIII. EM Piscium  

NASA Astrophysics Data System (ADS)

CCD photometric observations of the newly discovered close binary, EM Piscium, obtained from 2006 December 4 to 2008 January 7, are presented. The light curves are symmetric and show complete eclipses with an eclipse duration of 54 minutes. When comparing the present light curves with those published by González-Rojas et al., it is found that the depths of the two minima of the light curve have been interchanged, and the positive O'Connell effect has disappeared. The symmetric light curves in R and I bands were analyzed with the 2003 version of the W-D code. It is found that EM Piscium is a high fill-out overcontact binary system (f = 95.3 ± 2.7%) with an extreme mass ratio of q = 0.1487, suggesting that it is on the late evolutionary stage of late-type tidal-locked binaries. Based on the nine instances of light minimum that we determined and those published by previous investigators, it is discovered that the orbital period shows a cyclic period variation with a period of 3.3 years, while it undergoes a continuously rapid increase at a rate of dP/dt = +3.97 × 10-6 days year-1. The cyclic period reveals the presence of a tertiary companion, which may play an important role for the formation and evolution of the overcontact binary by drawing angular momentum from the central system via Kozai oscillation or a combination of Kozai cycle and tidal friction. The high fill-out, the extreme mass ratio, and the rapid period increase may suggest that the binary system is quickly evolving into a rapid-rotating single star.

Qian, S.-B.; He, J.-J.; Soonthornthum, B.; Liu, L.; Zhu, L.-Y.; Li, L.-J.; Liao, W. P.; Dai, Z.-B.

2008-11-01

112

Measurements of the Deuterium to Hydrogen Ratio in QSO Absorption Systems  

NASA Astrophysics Data System (ADS)

Observational constraints on the primordial deuterium-to-hydrogen ratio (D/H) can test theories of the early universe and provide constraints on models of Big Bang nucleosynthesis (BBN). We measure deuterium absorption in high-redshift, metal-poor QSO absorption systems and directly infer the value of primordial D/H. We present two measurements of D/H, and find D/H = 3.2±0.3×10-5 at z=3.572 towards QSO 1937-1009 and D/H = 4.0-0.8+0.6×10-5 at z=2.504 towards QSO 1009+2956. Both measurements use multiple-component Voigt profile analysis of high resolution, high signal-to-noise spectra and determinations of the Lyman continuum optical depth in low resolution spectra to constrain the column densities of deuterium and hydrogen. The measurements are consistent with a single primordial value of D/H = 3.4±0.3×10-5. This is a relatively low value, which supports homogeneous models of BBN and standard models of galactic chemical evolution. Using models of standard BBN, we find a cosmological baryon-to-photon ratio, ?=5.1±0.4×10-10, and a present-day baryon density in units of the critical density, ?b/ h1002=0.019±0.002. These values are consistent with high abundance measurements of 4He in extragalactic H II regions, and estimates of 7Li in warm, metal-poor halo stars.

Burles, Scott Michael

113

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

114

A ratio model of perceived speed in the human visual system  

PubMed Central

The perceived speed of moving images changes over time. Prolonged viewing of a pattern (adaptation) leads to an exponential decrease in its perceived speed. Similarly, responses of neurones tuned to motion reduce exponentially over time. It is tempting to link these phenomena. However, under certain conditions, perceived speed increases after adaptation and the time course of these perceptual effects varies widely. We propose a model that comprises two temporally tuned mechanisms whose sensitivities reduce exponentially over time. Perceived speed is taken as the ratio of these filters' outputs. The model captures increases and decreases in perceived speed following adaptation and describes our data well with just four free parameters. Whilst the model captures perceptual time courses that vary widely, parameter estimates for the time constants of the underlying filters are in good agreement with estimates of the time course of adaptation of direction selective neurones in the mammalian visual system. PMID:16243695

Hammett, Stephen T; Champion, Rebecca A; Morland, Antony B; Thompson, Peter G

2005-01-01

115

Experimental investigation of power loss coefficients and static pressure ratios in an industrial exhaust ventilation system.  

PubMed

A study tested whether measures of equivalent resistance (X values) and ratios of static pressure (SPratio) for given ducts of contaminant control exhaust ventilation systems were independent of substantial changes to airflow level and to changes to resistance of other ducts within the same full-scale five-branch system. In a factorial study design, four airflow levels were achieved by changing fan rotation rate while resistances to flow for specific branch ducts were changed independently by adjusting slidegate dampers to various settings. For each damper insertion depth (including fully open), the results demonstrated substantial invariance for branch X values (few greater than 5%), SPratio (few greater than 3%), and fraction of airflow to each duct (few greater than 2%). X-values for submains were much less stable, changing by 20% or more with changes to other parts of the system. For the same conditions, hood static pressures changed by as much as 96% (with standard deviation of 40%). The results suggest that before and after values of X and SPratios should be more reliable bases for indicating alterations than comparison of observed static pressures. The stability of airflow distributions with substantial changes in airflow suggests that one could adjust airflow distribution (e.g., with dampers) without considering whether the fan speed was set correctly, leaving fan adjustments for a final step. PMID:10386358

Guffey, S E; Spann, J G

1999-01-01

116

Characterization Of High-Stroke High-Aspect Ratio Micro Electro Mechanical Systems Deformable Mirrors For Adaptive Optics.  

E-print Network

??AbstractCharacterization Of High-Stroke High-Aspect Ratio Micro Electro Mechanical Systems Deformable Mirrors For Adaptive OpticsMohamed Amine BouchtiAdaptive optics MEMS deformable mirror, in conjunction with Shack Hartman… (more)

Bouchti, Mohamed Amine

2013-01-01

117

A third QSO absorption system with a low Deuterium/Hydrogen ratio  

NASA Astrophysics Data System (ADS)

We present high signal-to-noise ratio data on an extremely simple zabs ~ 3 partial Lyman limit absorption system. This absorber has only a single major velocity component, and unsaturated high order H I Lyman series lines. Hence, the parameters which describe the Hydrogen absorption are very well determined. We find excess absorption on the blue wing of the H I Lyalpha line, near to the expected position of deuterium absorption. The excess absorption is slight, allowing us to set a firm upper limit to the amount of deuterium absorption in this absorber, D/H < 6 x 10(-5) . However, the expected deuterium line is at the wrong wavelength to explain all of the excess absorption on the blue wing of the H I Lyalpha line, and hence there must be contamination by additional H I interloper absorption. Because the parameters of the H I interloper and the D line will be somewhat degenerate, we can not place a lower limit on D/H in this absorption system. We show that this system probably has a very low metallicity, [C/H] < -2, so that our upper limit of D/H < 6 x 10(-5) should be representative of primordial D/H. All four of the known high redshift absorption line systems simple enough to provide useful limits on D are consistent with the low value of D/H = 3.4 +/- 0.5 x 10(-5) measured towards QSO 1009+2956 and QSO 1937-1009 by Burles and Tytler (1998a, 1998b). Conversely, three of the four D/H limits are inconsistent with high D/H value proposed by Webb et al. (1997a, 1997b) towards QSO 1718+4807.

Kirkman, D.; Tytler, D.; Burles, S.; Lubin, D.; Omeara, J.

1999-05-01

118

Strehl ratio simulation results under strong turbulence conditions for actively compensated free-space optical communication systems  

NASA Astrophysics Data System (ADS)

Current Strehl ratio models for actively compensated free-space optical communications terminals do not accurately predict system performance under strong turbulence conditions as they are based on weak turbulence theory. For evaluation of compensated systems, we present an approach for simulating the Strehl ratio with both low-order (tip/tilt) and higher-order (adaptive optics) correction. Our simulation results are then compared to the published models and their range of turbulence validity is assessed. Finally, we propose a new Strehl ratio model that is valid for general turbulence conditions independent of the degree of compensation.

Juarez, Juan C.; Brown, David M.; Young, David W.

2013-05-01

119

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

NASA Astrophysics Data System (ADS)

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; Qiao, Xiaoyan; Wang, Mengjun; Zhang, Weibo; Li, Gang; Lin, Ling

2014-05-01

120

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

121

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

122

A sex-ratio Meiotic Drive System in Drosophila simulans. I: An Autosomal Suppressor  

PubMed Central

Sex ratio distortion (sex-ratio for short) has been reported in numerous species such as Drosophila, where distortion can readily be detected in experimental crosses, but the molecular mechanisms remain elusive. Here we characterize an autosomal sex-ratio suppressor from D. simulans that we designate as not much yang (nmy, polytene chromosome position 87F3). Nmy suppresses an X-linked sex-ratio distorter, contains a pair of near-perfect inverted repeats of 345 bp, and evidently originated through retrotransposition from the distorter itself. The suppression is likely mediated by sequence homology between the suppressor and distorter. The strength of sex-ratio is greatly enhanced by lower temperature. This temperature sensitivity was used to assign the sex-ratio etiology to the maturation process of the Y-bearing sperm, a hypothesis corroborated by both light microscope observations and ultrastructural studies. It has long been suggested that an X-linked sex-ratio distorter can evolve by exploiting loopholes in the meiotic machinery for its own transmission advantage, which may be offset by other changes in the genome that control the selfish distorter. Data obtained in this study help to understand this evolutionary mechanism in molecular detail and provide insight regarding its evolutionary impact on genomic architecture and speciation. PMID:17988172

Tao, Yun; Masly, John P; Araripe, Luciana; Ke, Yeyan; Hartl, Daniel L

2007-01-01

123

NUCLEAR PHYSICS: Impact Parameter Dependence of the Double Neutron/Proton Ratio of Nucleon Emissions in Isotopic Reaction Systems  

NASA Astrophysics Data System (ADS)

Within the transport model IBUU04, we investigate the double neutron/proton ratio of free nucleons taken from two reaction systems using two Sn isotopes at a beam energy of 50 MeV/nucleon and with impact parameters 2 fm, 4 fm and 8 fm, respectively. It is found that the double neutron/proton ratio from peripheral collisions is more sensitive to the density dependence of the symmetry energy than those from mid-central and central collisions.

Zhang, Xun-Chao; Li, Bao-An; Chen, Lie-Wen; Yong, Gao-Chan

2009-05-01

124

A Video Replacement Policy based on Revenue to Cost Ratio in aMulticast TV-Anytime System  

E-print Network

by the system during the runtime. Simulation results show that this policy leads to an efficient TV in the TV industry. The simulation results also show that multicasting significantly improves the sys- temA Video Replacement Policy based on Revenue to Cost Ratio in aMulticast TV-Anytime System Xiaobo

Xu, Cheng-Zhong

125

Temperature of shocked materials measured with an infrared pyrometer through a window  

NASA Astrophysics Data System (ADS)

We describe an experimental measurement technique which allows us to determine the interface temperature and the emissivity of shocked sample through window material (the lithium fluoride). We determine the temperature upon the partial release pressure of the sample. The infrared radiation emitted by the sample through the window material is collected and carried out to detectors by a four core fluoride glass optical fiber. The spectral bandwidth of this fiber is 1.5 micrometer to 4 micrometer. In order to deduce the temperature from the electrical signals amplified and recorded on a numerical oscilloscope, four narrow filters are used with different spectral bandwidth. A static calibration of the detectors with a black body is performed. Different ratios between static and dynamic measurements give access to the temperature as well as to the variation law of the emissivity versus wavelength. The shock generator for the dynamic experiment is an explosive plane wave generator. The shock pressure obtained is about 50 GPa. The purpose of this experimental measurement technique is the study of materials in solid phase as well as in liquid phase. Two samples have been studied, bismuth with solid- liquid transition at about 20 GPa and copper which remains solid in our pressure range.

Fribourg-Blanco, Eric; Remiot, Christian; Mexmain, Jean-Marc; Herve, Philippe J.

1996-06-01

126

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

127

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

PubMed Central

The evolution of heteromorphic sex chromosomes creates a genetic condition favoring the invasion of sex-ratio meiotic drive elements, resulting in the biased transmission of one sex chromosome over the other, in violation of Mendel's first law. The molecular mechanisms of sex-ratio meiotic drive may therefore help us to understand the evolutionary forces shaping the meiotic behavior of the sex chromosomes. Here we characterize a sex-ratio distorter on the X chromosome (Dox) in Drosophila simulans by genetic and molecular means. Intriguingly, Dox has very limited coding capacity. It evolved from another X-linked gene, which also evolved de nova. Through retrotransposition, Dox also gave rise to an autosomal suppressor, not much yang (Nmy). An RNA interference mechanism seems to be involved in the suppression of the Dox distorter by the Nmy suppressor. Double mutant males of the genotype dox; nmy are normal for both sex-ratio and spermatogenesis. We postulate that recurrent bouts of sex-ratio meiotic drive and its subsequent suppression might underlie several common features observed in the heterogametic sex, including meiotic sex chromosome inactivation and achiasmy. PMID:17988173

Tao, Yun; Araripe, Luciana; Kingan, Sarah B; Ke, Yeyan; Xiao, Hailian; Hartl, Daniel L

2007-01-01

128

Carrier: Interference ratios for frequency sharing between satellite systems transmitting frequency modulated and digital television signals  

NASA Technical Reports Server (NTRS)

Results are presented of subjective and quantitative tests describing the results of interference to a particular digital television system from a frequency modulated (FM) television system, and for interference to an FM television system from a digital television system.

Barnes, S. P.

1979-01-01

129

THE DETERMINATION OF ATOMIC RATIOS IN THE URANIUM-OXYGEN SYSTEM BY A THERMOGRAVIMETRIC METHOD  

Microsoft Academic Search

A description is given of a thermogravimetric oxidation- reduction ; method for determining U -O ratios, especially suited to oxygen-sensitive ; materials of undetermined purity, and equally applicable to pure stoichiometric ; and non-stoichiometric oxides and their mixtures with each other and with uranium ; metal. Provided that no uncombined base metals other than uranium, and no ; oxidizable or

L. G. Stonhill

1959-01-01

130

Limit to the Bit-Rate Capacity of Electrical Interconnects from the Aspect Ratio of the System Architecture  

E-print Network

of the conductors (for example, the "skin depth" in copper at 1 GHz is about 2 Pm). In practical cables, the skinLimit to the Bit-Rate Capacity of Electrical Interconnects from the Aspect Ratio of the System. Ã?zaktas Bilkent University Department of Electrical Engineering TR-06533 Bilkent Ankara, Turkey Preprint G

Miller, David A. B.

131

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

132

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

133

Molecular beam sampling system with very high beam-to-background ratio: The rotating skimmer concept  

Microsoft Academic Search

A novel method of reducing the background pressure in a vacuum system used for sampling a molecular beam from a high pressure region is presented. A triple differential pumping stage is constructed with a chopper with rotating skimmer within the first pumping stage, which serves effectively as a valve separating periodically the vacuum system from the ambient environment. The mass

J. Benedikt; D. Ellerweg; A. von Keudell

2009-01-01

134

The molecular branching ratio method for calibration of optical systems in the vacuum ultraviolet  

NASA Technical Reports Server (NTRS)

The intensity distribution of bands belonging to six molecular band systems is discussed with special emphasis on their usefulness for intensity calibration of optical systems in the vacuum ultraviolet (1000A Lambda 3000A). The theory of molecular band intensities is outlined and the technique of measuring the spectral response curve is described. Several methods for establishing an absolute intensity calibration are discussed.

Mumma, M. J.

1972-01-01

135

Emergy\\/exergy ratio as a measure of the level of organization of systems  

Microsoft Academic Search

Emergy and exergy have been developed as complementary goal functions. By definition, emergy is the solar energy directly and indirectly required to generate a flow or a storage. Exergy is a property of a system, measuring the maximum work that can be extracted from a system when it goes towards the thermodynamic equilibrium with a reference state. The concept of

Simone Bastianoni; Nadia Marchettini

1997-01-01

136

Influence of D/A ratio on photovoltaic performance of a highly efficient polymer solar cell system.  

PubMed

A new copolymer PIDTDTQx based on indacenodithiophene and quinoxaline is synthesized and characterized. The correlation between the D/A ratio, mobility, and photovoltaic properties, as well as morphology of the D/A blend based on a PIDTDTQx:PC(70) BM system is investigated. The power conversion efficiency of the polymer solar cells based on PIDTDTQx/PC(70) BM (1:4, w/w) reaches 7.51%. PMID:23044822

Guo, Xia; Zhang, Maojie; Tan, Jiahui; Zhang, Shaoqing; Huo, Lijun; Hu, Wenping; Li, Yongfang; Hou, Jianhui

2012-12-18

137

Solar load ratio method applied to commercial building active solar system sizing  

SciTech Connect

The hourly simulation procedure is the DOE-2 building energy analysis computer program. It is capable of calculating the loads and of simulating various control strategies in detail for both residential and commercial buildings and yet is computationally efficient enough to be used for extensive parametric studies. In addition, to a Building Service Hot Water (BSHW) System and a combined space heating and hot water system using liquid collectors for a commercial building analyzed previously, a space heating system using an air collector is analyzed. A series of runs is made for systems using evacuated tube collectors for comparison to flat-plate collectors, and the effects of additional system design parameters are investigated. Also, the generic collector types are characterized by standard efficiency curves, rather than by detailed collector specifications. (MHR)

Schnurr, N.M.; Hunn, B.D.; Williamson, K.D. III

1981-01-01

138

A multi-wavelength streak-optical-pyrometer for warm-dense matter experiments at NDCX-I and NDCX-II  

NASA Astrophysics Data System (ADS)

We report on a multi-wavelength streak-optical-pyrometer (SOP) developed the for warm-dense-matter (WDM) experiments at the existing NDCX-I facility and the NDCX-II facility currently being commissioned at LBNL. The SOP served as the primary temperature diagnostic in the recent NDCX-I experiments, in which an intense K+ beam was used to heat different metal samples into WDM states. The SOP consists of a spectral grating (visible and near-infrared spectral range) and a fast, high-dynamic-range optical streak camera. The instrument is calibrated absolutely with a NIST-traceable tungsten ribbon lamp and can itself be considered as an absolutely calibrated, time-resolving spectrometer. The sample temperature is determined from fitting the recorded thermal spectrum into the Planck formula multiplied by a model of emissivity.

Ni, P. A.; Bieniosek, F. M.; Henestroza, E.; Lidia, S. M.

2014-01-01

139

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

140

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

141

Local dynamics of a fast-evolving sex-ratio system in Drosophila simulans.  

PubMed

By distorting Mendelian transmission to their own advantage, X-linked meiotic drive elements can rapidly spread in natural populations, generating a sex-ratio bias. One expected consequence is the triggering of a co-evolutionary arms race between the sex chromosome that carries the distorter and suppressors counteracting its effect. Such an arms race has been theoretically and experimentally established and can have many evolutionary consequences. However, its dynamics in contemporary populations is still poorly documented. Here, we investigate the fate of the young X-linked Paris driver in Drosophila simulans from sub-Saharan Africa to the Middle East. We provide the first example of the early dynamics of distorters and suppressors: we find consistent evidence that the driving chromosomes have been rising in the Middle East during the last decade. In addition, identical haplotypes are at high frequencies around the two co-evolving drive loci in remote populations, implying that the driving X chromosomes share a recent common ancestor and suggesting that East Africa could be the cradle of the Paris driver. The segmental duplication associated with drive presents an unusual structure in West Africa, which could reflect a secondary state of the driver. Together with our previous demonstration of driver decline in the Indian Ocean where suppression is complete, these data provide a unique picture of the complex dynamics of a co-evolutionary arms race currently taking place in natural populations of D. simulans. PMID:24118375

Bastide, Héloïse; Gérard, Pierre R; Ogereau, David; Cazemajor, Michel; Montchamp-Moreau, Catherine

2013-11-01

142

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

143

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

144

Improvement of the Compton suppression ratio of a standard BGO suppressor system by a digital pulse shape analysis  

NASA Astrophysics Data System (ADS)

We have applied a digital pulse shape analysis (DPSA) to Compton suppression for a high-purity coaxial germanium detector (HPGe) as a means of verifying the DPSA method that we have recently developed to extract information for the interaction positions of gamma rays in semiconductor detectors. Our DPSA method is based on chi-square fitting the measured pulse shapes to the calculated ones obtained by the weighting potential method. In order to investigate the performance of the Compton suppression technique using our DPSA method, we have extracted the experimental peak-to-total (P/T) ratios for 662-keV gamma rays emitted from a 137Cs standard source. The experimental P/T ratios were compared with the ones obtained by a conventional BGO suppressor system. Applying the Compton suppression technique using the DPSA method to the BGO suppression system, we could also improve the P/T ratios. The experimental results were in good accord with the ones obtained by a Monte Carlo simulation.

Jung, H. S.; Cho, H. Y.; Lee, J. H.; Lee, C. S.

2007-10-01

145

Peak-to-Average Power Ratio Reduction in OFDM Systems using Huffman Coding  

Microsoft Academic Search

? Abstract— In this paper we proposed the use of Huffman coding to reduce the PAR of an OFDM system as a distortion- less scrambling technique, and we utilize the amount saved in the total bit rate by the Huffman coding to send the encoding table for accurate decoding at the receiver without reducing the effective throughput. We found that

Ashraf A. Eltholth; Adel R. Mikhail; A. Elshirbini; Moawad I. Moawad; A. I. Abdelfattah

2008-01-01

146

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

147

Solar load ratio method applied to commercial building active solar system sizing  

Microsoft Academic Search

The DOE-2 building energy analysis computer program is described. It is capable of calculating the loads and of simulating various control strategies in detail for both residential and commercial buildings and yet is computationally efficient enough to be used for extensive parameteric studies. In addition to a Building Service Hot Water System and a combined space heating and hot water

N. M. Schnurr; B. D. Hunn; K. D. Williamson III

1981-01-01

148

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.

149

Rod Ratios  

NSDL National Science Digital Library

This activity builds student knowledge of ratios by using Cuisenaire rods to determine proportion and form equivalent ratios. Students may use the Cuisenaire rod environment embedded in this resource or they may use actual Cuisenaire rods depending on preference/ability/accessibility. This resource includes teacher notes, solution, and suggestions for questioning.

Team, Nrich

2013-01-01

150

Frequency-dependent population dynamics: Effect of sex ratio and mating system on the elasticity of population growth rate.  

PubMed

When vital rates depend on population structure (e.g., relative frequencies of males or females), an important question is how the long-term population growth rate ? responds to changes in rates. For instance, availability of mates may depend on the sex ratio of the population and hence reproductive rates could be frequency-dependent. In such cases change in any vital rate alters the structure, which in turn, affect frequency-dependent rates. We show that the elasticity of ? to a rate is the sum of (i) the effect of the linear change in the rate and (ii) the effect of nonlinear changes in frequency-dependent rates. The first component is always positive and is the classical elasticity in density-independent models obtained directly from the population projection matrix. The second component can be positive or negative and is absent in density-independent models. We explicitly express each component of the elasticity as a function of vital rates, eigenvalues and eigenvectors of the population projection matrix. We apply this result to a two-sex model, where male and female fertilities depend on adult sex ratio ? (ratio of females to males) and the mating system (e.g., polygyny) through a harmonic mating function. We show that the nonlinear component of elasticity to a survival rate is negligible only when the average number of mates (per male) is close to ?. In a strictly monogamous species, elasticity to female survival is larger than elasticity to male survival when ?<1 (less females). In a polygynous species, elasticity to female survival can be larger than that of male survival even when sex ratio is female biased. Our results show how demography and mating system together determine the response to selection on sex-specific vital rates. PMID:25174884

Haridas, C V; Eager, Eric Alan; Rebarber, Richard; Tenhumberg, Brigitte

2014-11-01

151

A Method for Calibrating Camera Lens Distortion with Cross-Ratio Invariability in Welding Seam System  

Microsoft Academic Search

Wide-Angle lenses have broad applications in lots of fields for their larger fields of view. However, image deformation is\\u000a its main backward. Thus, calibration of distortion parameters of wide-angle lens is an essential procedure for 3D information\\u000a recovering from 2D images in applications. Based on our 3D welding seam extraction system, we propose a nonlinear calibration\\u000a method by using calibration

Guangtao Zhao; Hong Qiao

2008-01-01

152

CONSTRAINING MASS RATIO AND EXTINCTION IN THE FU ORIONIS BINARY SYSTEM WITH INFRARED INTEGRAL FIELD SPECTROSCOPY  

SciTech Connect

We report low-resolution near-infrared spectroscopic observations of the eruptive star FU Orionis using the Integral Field Spectrograph (IFS) Project 1640 installed at the Palomar Hale telescope. This work focuses on elucidating the nature of the faint source, located 0.''5 south of FU Ori, and identified in 2003 as FU Ori S. We first use our observations in conjunction with published data to demonstrate that the two stars are indeed physically associated and form a true binary pair. We then proceed to extract J- and H-band spectro-photometry using the damped LOCI algorithm, a reduction method tailored for high contrast science with IFS. This is the first communication reporting the high accuracy of this technique, pioneered by the Project 1640 team, on a faint astronomical source. We use our low-resolution near-infrared spectrum in conjunction with 10.2 {mu}m interferometric data to constrain the infrared excess of FU Ori S. We then focus on estimating the bulk physical properties of FU Ori S. Our models lead to estimates of an object heavily reddened, A{sub V} = 8-12, with an effective temperature of {approx}4000-6500 K. Finally, we put these results in the context of the FU Ori N-S system and argue that our analysis provides evidence that FU Ori S might be the more massive component of this binary system.

Pueyo, Laurent [Johns Hopkins University, Department of Physics and Astronomy, 366 Bloomberg Center 3400 N. Charles Street, Baltimore, MD 21218 (United States); Hillenbrand, Lynne; Hinkley, Sasha; Dekany, Richard; Roberts, Jenny [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Vasisht, Gautam; Roberts, Lewis C. Jr.; Shao, Mike; Burruss, Rick; Cady, Eric [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Oppenheimer, Ben R.; Brenner, Douglas; Zimmerman, Neil [American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Monnier, John D. [Department of Astronomy, University of Michigan, 941 Dennison Building, 500 Church Street, Ann Arbor, MI 48109-1090 (United States); Crepp, Justin [Department of Physics, 225 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556 (United States); Parry, Ian [University of Cambridge, Institute of Astronomy, Madingley Road, Cambridge, CB3, OHA (United Kingdom); Beichman, Charles [NASA Exoplanet Science Institute, 770 South Wilson Avenue, Pasadena, CA 91225 (United States); Soummer, Remi [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2012-09-20

153

A dynamic exposure system: Concurrent toluene inhalation and fixed ratio performance in mice  

SciTech Connect

The potential for occupational exposure to acute high doses of solvents, coupled with the rising incidence of inhalant abuse, necessitates the need to better characterize the behavioral effects of solvents. Vapor exposure was accomplished with a computer-controlled mass flow system where exposure levels were monitored by infrared spectroscopy. Twelve food-deprived CFW male mice were shaped to lever press for milk reinforcement under a FR20 schedule. Within-session concentration-effect relationships for toluene were determined by successive 5-minute exposures to 5 successively increasing concentrations, preceded by 5 minutes of air exposure. These results were compared to concentration-effect relationships determined by single concentration test sessions, utilizing 20-minute exposures, preceded and followed by 5 minutes of air exposure. Under the within-session method, very similar concentration related decreases in response rates were produced, regardless of whether the concentration range examined was 500-6,000 ppm or 125-2,000 ppm. Effects of toluene based upon exposure to single concentrations yielded a less sensitive effect for the concentration range 125-2,000 ppm. Return to baseline response rates were rapid, correlating well with the rapid rate of clearance classically exhibited by solvents. These results indicate that this dynamic mass flow system provides a sensitive and consistent means by which to measure the behavioral effects of inhalants and allows for a great deal of flexibility for rapid alteration of exposure conditions.

Tegeris, J.S.; Knisely, J.S.; Balster, R.L. (Medical Coll. of Virginia, Richmond (United States))

1990-02-26

154

Direct-drive high-convergence-ratio implosion studies on the OMEGA laser system  

NASA Astrophysics Data System (ADS)

A series of direct-drive implosion experiments, using room-temperature, gas-filled CH targets, are performed on the University of Rochester's OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The target performance at stagnation and its dependence on beam smoothing and pulse shaping is investigated. Compressed core conditions are diagnosed using x-ray and neutron spectroscopy, and x-ray imaging. The individual beams of OMEGA are smoothed by spectral dispersion in two dimensions (2D SSD) with laser bandwidths up to ˜0.3 THz, with 1 ns square to 2.5 ns shaped pulses. A clear dependence of target performance on pulse shape and beam smoothing is seen, with the target performance (yield, areal density, and shell integrity) improving as SSD bandwidth is applied.

Marshall, F. J.; Delettrez, J. A.; Epstein, R.; Glebov, V. Yu.; Harding, D. R.; McKenty, P. W.; Meyerhofer, D. D.; Radha, P. B.; Seka, W.; Skupsky, S.; Smalyuk, V. A.; Soures, J. M.; Stoeckl, C.; Town, R. P. J.; Yaakobi, B.; Li, C. K.; Séguin, F. H.; Hicks, D. G.; Petrasso, R. D.

2000-05-01

155

Photometric study and preliminary elements of the low-mass ratio W UMa system ASAS 021209+2708.3  

NASA Astrophysics Data System (ADS)

We present CCD B and V light curves, obtained in the year 2006, and a photometric solution of the low-mass ratio contact binary ASAS 021209+2708.3. With our data we were able to determine six new times of minimum light and refine the orbital period of the system to 0.3181963 days. The light curves are analyzed using the 2003 version of the Wilson-Devinney program and the analysis was performed with and without adding a spot on the surface of one star because the light curves appear to exhibit a typical O'Connell effect, with Maximum I brighter than Maximum II. The results show that ASAS 021209+2708.3 may be classified as an A-subtype W Ursae Majoris system with a small mass ratio q = 0.1889, a large over-contact degree of f = 0.587, a very small difference between the component temperatures of ?T = 53 K and an orbital inclination of i = 81°. It is known that deep (f > 50%), low-mass ratio (q < 0.25) overcontact binary stars are a very important resource for understanding the phenomena of Blue Straggler/FK Com-type stars. The formations of Blue Straggler stars and FK Com-type stars are unsolved problems in stellar astrophysics. One of the possible explanations for their formation is from the coalescence of W UMa-type overcontact binary systems. The absolute dimensions of ASAS 021209+2708.3 are estimated and its dynamical evolution is inferred.

Acerbi, Francesco; Barani, Carlo; Martignoni, Massimiliano

2011-07-01

156

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

157

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

158

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

159

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

160

Full-duplex radio over fiber system with optimum optical carrier to sideband ratio and wavelength reuse  

NASA Astrophysics Data System (ADS)

A full-duplex radio over fiber system with optimum optical carrier to sideband ratio (OCSR) of 0 dB and wavelength reuse for uplink are proposed. At the central office, single-sideband modulation with OCSR larger than 0 dB is realized based on optical injection. At the base station, a notch filter with the notch depth corresponding to the OCSR of the transmitted signal is used to achieve the optimum OCSR of 0 dB. The reflected weakly modulated carrier is reused as the carrier for upload signals. A simulation is carried out to verify the proposed system. Results show that the download 60-GHz-RF signal is almost not affected by the fiber chromatic dispersion, and the power penalty after transmission over a 50-km single-mode fiber is negligible in uplink and is only 1.27 dB in downlink.

Xiong, Jintian; Wang, Rong; Pu, Tao; Fang, Tao; Zheng, Jilin; Lu, Lin; Xiang, Peng

2014-06-01

161

System size and beam energy effects on probing the high-density behavior of nuclear symmetry energy with pion ratio  

NASA Astrophysics Data System (ADS)

Based on the isospin-and momentum-dependent hadronic transport model IBUU04, we have investigated the ?-/?+ ratio in the following three reactions: 48Ca+48Ca, 124Sn + 124Sn and 197Au + 197Au with nearly the same isospin asymmetry but different masses, at the bombarding energies from 0.25 to 0.6 AGeV. It is shown that the sensitivity of probing the E(?) with ?-/?+ increases with increasing the system size or decreasing the beam energy, showing a correlation to the degree of isospin fractionation. Therefore, with a given isospin asymmetry, heavier system at energies near the pion threshold is preferential to study the behavior of nuclear symmetry energy at supra-saturation densities.

Zhang, Ming; Xiao, Zhi-Gang; Li, Bao-An; Chen, Lie-Wen; Yong, Gao-Chan; Zhu, Sheng-Jiang

2010-03-01

162

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

163

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

164

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

165

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

166

Effect of inspiration-expiration ratio on rebreathing with the Mapleson D system (Bain's modification; coaxial system).  

PubMed

Rebreathing in the Mapleson D system with a varying fresh gas flow (FGF) was measured during an experimental set-up, which consisted of a compliance lung delivering the exhaled gases with the same, fixed concentration throughout the experiment, a commercially available Bain's system and a respirator. While changes in compliance, airway resistance an dead space hardly influenced the degree of rebreathing, changes in ventilatory pattern did so when the length of the expiratory pause was changed. Thus, with the Vt used which was not essentially greater than the capacity of the corrugated tube, a sufficiently long-lasting expiratory pause made it possible to establish non-rebreathing conditions with a FGF only slightly greater than the respiratory minute volume. Obviously, a short or no expiratory pause requires that the FGF rate be high enough to compensate for the lack of a fresh gas reserve in the corrugated tube at the start of inspiration. In such cases the length of the corrugated tube becomes of minor or no importance. PMID:6781209

Gabrielsen, J; van den Berg, J T; Dirksen, H; Ruben, H

1980-08-01

167

Laser-assisted scanning probe alloying nanolithography (LASPAN) and its application in gold-silicon system  

E-print Network

surface after scratching. .......... 66 39 Schematic diagram for NIR Pyrometer Microscope .................................. 71 xii FIGURE... Page 40 Real set-up for NIR pyrometer microscope ............................................... 72 41 Calibration of this NIR pyrometer. ............................................................ 74 42 Temperature measurement of a laser...

Peng, Luohan

2009-05-15

168

Water and organic matter D\\/H ratios in the solar system: a record of an early irradiation of the nebula?  

Microsoft Academic Search

Water and organic molecules are intimately mixed in the primitive planetary objects of the solar system such as Meteorites and Comets. In few rare examples, the D\\/H ratios of both water and organic matter (OM) have been measured independently. A critical review of these data are presented.Based on the comparison between the water and OM D\\/H ratios, it seems possible

François Robert

2002-01-01

169

Effects of NH4:NO3:urea ratio on cut roses yield, leaf nutrients content and proton efflux by roots in closed hydroponic system  

E-print Network

in closed hydroponic system B. Bar-Yosef a, *, N.S. Mattson b,1 , H.J. Lieth b a Agricultural Research Article history: Received 18 February 2009 Received in revised form 27 May 2009 Accepted 4 June 2009 previously in closed (no leaching) hydroponic systems. A greenhouse experiment with six NH4:NO3:urea ratios

Lieth, J. Heinrich

170

System-size dependence of particle-ratio fluctuations in Pb + Pb collisions at 158A GeV  

NASA Astrophysics Data System (ADS)

New measurements by the NA49 experiment of the centrality dependence of event-by-event fluctuations of the particle yield ratios (K++K-)/(?++?-), (p+p¯)/(?++?-), and (K++K-)/(p+p¯) are presented for Pb+Pb collisions at 158A GeV. The absolute values of the dynamical fluctuations of these ratios, quantified by the measure ?dyn, increase by about a factor of two from central to semiperipheral collisions. Multiplicity scaling scenarios are tested and found to apply for both the centrality and the previously published energy dependence of the (K++K-)/(?++?-) and (p+p¯)/(?++?-) ratio fluctuations. A description of the centrality and energy dependence of (K++K-)/(p+p¯) ratio fluctuations by a common scaling prescription is not possible since there is a sign change in the energy dependence.

Anticic, T.; Baatar, B.; Barna, D.; Bartke, J.; Beck, H.; Betev, L.; Bia?kowska, H.; Blume, C.; Bogusz, M.; Boimska, B.; Book, J.; Botje, M.; Bun?i?, P.; Cetner, T.; Christakoglou, P.; Chung, P.; Chvála, O.; Cramer, J. G.; Eckardt, V.; Fodor, Z.; Foka, P.; Friese, V.; Ga?dzicki, M.; Grebieszkow, K.; Höhne, C.; Kadija, K.; Karev, A.; Kolesnikov, V. I.; Kollegger, T.; Kowalski, M.; Kresan, D.; László, A.; Lacey, R.; van Leeuwen, M.; Ma?kowiak-Paw?owska, M.; Makariev, M.; Malakhov, A. I.; Mateev, M.; Melkumov, G. L.; Mitrovski, M.; Mrówczy?ski, St.; Nicolic, V.; Pálla, G.; Panagiotou, A. D.; Peryt, W.; Pluta, J.; Prindle, D.; Pühlhofer, F.; Renfordt, R.; Roland, C.; Roland, G.; Rybczy?ski, M.; Rybicki, A.; Sandoval, A.; Schmitz, N.; Schuster, T.; Seyboth, P.; Siklér, F.; Skrzypczak, E.; S?odkowski, M.; Stefanek, G.; Stock, R.; Ströbele, H.; Susa, T.; Szuba, M.; Utvi?, M.; Varga, D.; Vassiliou, M.; Veres, G. I.; Vesztergombi, G.; Vrani?, D.; W?odarczyk, Z.; Wojtaszek-Szwarc, A.

2013-02-01

171

Between-Year Variation in Population Sex Ratio Increases with Complexity of the Breeding System in Hymenoptera.  

E-print Network

, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive occurs in social Hymenoptera, long-term studies have revealed substantial un- explained between-year variation in population sex ratio in multiple-queen eu- social species, which supports the view

Alvarez, Nadir

172

2000 Conference on Information Sciences and Systems, Princeton University, March 15-17, 2000 The Competitive Complexity Ratio  

E-print Network

The Competitive Complexity Ratio R. A. Stine and D. P. Foster1 Department of Statistics The Wharton School by a model which benefits from side information. The side information bounds the sizes of unknown parameters complexity is a property of the model class M and is invariant of Y . It thus serves as a uniform measure

Stine, Robert A.

173

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

174

New measurement method of Poisson's ratio of PVA hydrogels using an optical flow analysis for a digital imaging system  

NASA Astrophysics Data System (ADS)

In this paper, we propose a method to observe deformation, to measure strain and to calculate Poisson's ratio of a soft material such as a polyvinyl alcohol hydrogel by means of an optical flow analysis during a tensile test. Compared to the conventional digital image correlation method of which the basic assumption is that the local target region in an image is under linear deformation, an optical flow method can measure local deformation up to the pixel level of the image. In addition, sub-pixel measurements are possible by means of bi-cubic interpolation of each flow vector. To guarantee the accuracy of the optical flow vectors, the scale-invariant feature transform was used. Random sample consensus (RANSAC) for eliminating noisy features and then obtaining a more accurate result was applied. The mean value of Poisson's ratio is 0.4498 and the standard deviation comes to 0.0305. This optical flow method can also be applied to calculate Poisson's ratio of other soft materials.

Chen, Feifei; Kang, Dong-Joong; Park, Jun-Hyub

2013-05-01

175

40 CFR 141.536 - My system has developed an inactivation ratio; what must we do now?  

Code of Federal Regulations, 2010 CFR

...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Profile § 141.536 My system has...

2010-07-01

176

40 CFR 141.534 - How does my system use this data to calculate an inactivation ratio?  

Code of Federal Regulations, 2011 CFR

...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Profile § 141.534 How does my system...

2011-07-01

177

40 CFR 141.534 - How does my system use this data to calculate an inactivation ratio?  

Code of Federal Regulations, 2010 CFR

...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Profile § 141.534 How does my system...

2010-07-01

178

40 CFR 141.536 - My system has developed an inactivation ratio; what must we do now?  

Code of Federal Regulations, 2011 CFR

...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Profile § 141.536 My system has...

2011-07-01

179

SEMICONDUCTOR INTEGRATED CIRCUITS: A variable step-down conversion ratio switched capacitor DC-DC converter for energy harvesting systems working in intermittent mode  

NASA Astrophysics Data System (ADS)

Energy harvesting systems stimulate the development of power management for low power consumption applications. Improving the converter efficiency of power management circuits has become a significant issue in energy harvesting system design. This paper presents a variable step-down conversion ratio switched capacitor (SC) DC-DC converter to advance the converter efficiency of charge on the stored capacitor in a wireless monitoring system of orthopedic implants. The converter is designed to work at 1 MHz switching frequency and achieves 15 to 2 V conversion. Measurement results show that the converter efficiency can reach 42% including all circuit power consumption, which is much higher than previous work.

Wenhan, Hao; Chen, Jia; Hong, Chen; Chun, Zhang; Zhihua, Wang

2009-12-01

180

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.

181

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

DOEpatents

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

182

Learning About Ratios  

NSDL National Science Digital Library

Ratios appear in everyday life, but what exactly is a ratio. This lesson will help you understand what is a ratio and what to do with a ratio. What is a ratio? Dr. Math gives a pretty good explanation on these sites What is a ratio? Ratios as Fractions Figuring Ratios Writing Ratios Ratios Use this site to explore ratios using pictures All About Ratios Now that you have a little understanding here are some in-class activities that your teacher can help you with ...

Hadley, Mrs.

2005-06-17

183

Alkali injection system with controlled CO.sub.2 /O.sub.2 ratios for combustion of coal  

DOEpatents

A high temperature combustion process for an organic fuel containing sulfur n which the nitrogen of air is replaced by carbon dioxide for combination with oxygen with the ratio of CO.sub.2 /O.sub.2 being controlled to generate combustion temperatures above 2000 K. for a gas-gas reaction with SO.sub.2 and an alkali metal compound to produce a sulfate and in which a portion of the carbon-dioxide rich gas is recycled for mixing with oxygen and/or for injection as a cooling gas upstream from heating exchangers to limit fouling of the exchangers, with the remaining carbon-dioxide rich gas being available as a source of CO.sub.2 for oil recovery and other purposes.

Berry, Gregory F. (Naperville, IL)

1988-01-01

184

The Activity of the Hypothalamic-Pituitary-Adrenal Axis and the Sympathetic Nervous System in Relation to Waist\\/Hip Circumference Ratio in Men  

Microsoft Academic Search

Objective: To investigate possible differences, between generally and abdominally obese men, in activity and regulation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system.Research Methods and Procedures: Fifty non-diabetic, middle-aged men were selected to obtain two groups with similar body mass index (BMI) but different waist\\/hip circumference ratio (WHR). Measurements were performed of the activity of the HPA axis

Thomas Ljung; Göran Holm; Peter Friberg; Björn Andersson; Bengt-Åke Bengtsson; Johan Svensson; Mary Dallman; Bruce McEwen; Per Björntorp

2000-01-01

185

The Cosmological Baryon Density from the Deuterium-to-Hydrogen Ratio in QSO Absorption Systems: D\\/H toward Q1243+3047  

Microsoft Academic Search

We report the detection of deuterium absorption at redshift 2.525659 toward Q1243+3047. We describe improved methods to estimate the deuterium to hydrogen abundance ratio (D\\/H) in absorption systems, including improved modeling of the continuum level, the Lyalpha forest, and the velocity structure of the absorption. Together with improved relative flux calibration, these methods give D\\/H=2.42+0.35-0.25×10-5 from our Keck I HIRES

David Kirkman; David Tytler; Nao Suzuki; John M. O'Meara; Dan Lubin

2003-01-01

186

Investigation of Influence of Gas Ratio on the Electron Temperature in TiN Magnetron Sputtering Deposition System.  

National Technical Information Service (NTIS)

In this work, a nanolayer of titanium nitride which produced by the magnetron sputtering system is synthesized. Moreover the effect of plasma parameters on the electron temperature is studied. Electron temperature has a significant effect on the plasma co...

A. R. Niknam, H. Latifi, H. R. Ghomi, S. Ghasemi

2013-01-01

187

Fabrication of High-Resolution and High-Aspect-Ratio Patterns on a Stepped Substrate by Using Scanning Probe Lithography with a Multilayer-Resist System  

NASA Astrophysics Data System (ADS)

The high-resolution and high-aspect-ratio resist-patterning method using a trilayer-resist system with atomic force microscopy (AFM) lithography is described. This system consists of a high-resolution negative-type resist as a top layer, p-Si as an intermediate layer, and an organic resist as a bottom layer. Since the bottom layer planarizes the surface, the patterns can be fabricated on a stepped surface. Using this method, we successfully fabricate 50-nm-wide and 340-nm-thick line-and-space resist patterns on a 200-nm-stepped substrate.

Ishibashi, Masayoshi; Sugita, Nami; Heike, Seiji; Kajiyama, Hiroshi; Hashizume, Tomihiro

1999-04-01

188

Polaradiometric pyrometer in which the parallel and perpendicular components of radiation reflected from an unpolarized light source are equalized with the thermal radiation emitted from a measured object to determine its true temperature  

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)

1995-01-01

189

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.

190

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

E-print Network

HVAC Technologies for Energy Efficiency, Vol. IV-6-1 ethanol fed SOFC-based electricity generating systems in terms of energy and exergy [J]. Journal of Power Source, 114(2003): 203-212 [7] S.H Chan, H.K. Ho, Y. Tian. Modelling for part load....H. Chan, C.F. Low, O.L. Ding. Energy and exergy analysis of simple solid fuel cell power systems [J]. Journal of Power Sources 103(2002): 188-200 [17] S. Douvartzides, F. Coutelieris, P, Tsiakaras. Exergy analysis of solid oxide fuel cell power plant...

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

2006-01-01

191

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

192

Engineered high aspect ratio vertical nanotubes as a model system for the investigation of catalytic methanol synthesis over Cu/ZnO.  

PubMed

Catalytically synthesized methanol from H2 and CO2 using porous Cu/ZnO aggregates is a promising, carbon neutral, and renewable alternative to replace fossil fuel based transport fuels. However, the absence of surface-engineered model systems to understand and improve the industrial Cu/ZnO catalyst poses a big technological gap in efforts to increase industrial methanol conversion efficiency. In this work, we report a novel process for the fabrication of patterned, vertically aligned high aspect ratio 1D nanostructures on Si that can be used as an engineered model catalyst. The proposed strategy employs near-field phase shift lithography (NF-PSL), deep reactive ion etching (DRIE), and atomic layer deposition (ALD) to pattern, etch, and coat Si wafers to produce high aspect ratio 1D nanostructures. Using this method, we produced a model system consisting of high aspect ratio Cu-decorated ZnO nanotubes (NTs) to investigate the morphological effects of ZnO catalyst support in comparison to the planar Cu/ZnO catalyst in terms of the catalytic reactions. The engineered catalysts performed 70 times better in activating CO2 than the industrial catalyst. In light of the obtained results, several important points are highlighted, and recommendations are made to achieve higher catalytic performance. PMID:24392784

Güder, Firat; Frei, Elias; Kücükbayrak, Umut M; Menzel, Andreas; Thomann, Ralf; Luptak, Roman; Hollaender, Bernd; Krossing, Ingo; Zacharias, Margit

2014-02-12

193

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

194

The use of 87 Sr\\/ 86 Sr ratios to document physico-chemical changes in shallow-water hydrothermal systems  

Microsoft Academic Search

The dominant precipitates in the hydrothermal system at Ambitle Island are aragonite and hy- drous ferric oxide (HFO). Their precipitation occurs due to a change in Eh, pH, temperature and chemical composition when the hydrothermal fluids discharge and mix with ambient seawater. The amount of sea- water-hydrothermal fluid mixing during their precipitation was calculated using strontium isotopes. Based on a

T. Pichler

195

Degree of hydration and gel\\/space ratio of high-volume fly ash\\/cement systems  

Microsoft Academic Search

Although fly ash has been widely used in concrete as a cement replacement, little work has been done on determining the degree of hydration of high-volume fly ash\\/cement (FC) systems. In the present study, the degree of hydration of the cement in Portland cement (PC) paste was obtained by determining the non-evaporable water (Wn) content. The degree of reaction of

L Lam; Y. L Wong; C. S Poon

2000-01-01

196

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

NASA Astrophysics Data System (ADS)

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 [S. Akcay et al., Phys. Rev. D 86, 104041 (2012)]. 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 [Y. Pan et al., Phys. Rev. D 84, 124052 (2011) and T. Damour et al., Phys. Rev. D 87, 084035 (2013)] 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 Phys. Rev. D 62, 124022 (2000) by including finite mass-ratio corrections and modeling the orbital phase evolution using an implicit rotating source [J. G. Baker et al., Phys. Rev. D 78, 044046 (2008)]. 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 modeling based on a sum of quasinormal modes.

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

2014-07-01

197

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 so...

Huerta, E A; Gair, Jonathan R; McWilliams, Sean T

2014-01-01

198

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

2014-03-03

199

Ratios and Proportions  

NSDL National Science Digital Library

In this learning object from Wisc-Online, students will examine ratios and proportions. The unit's activities include defining ratios and proportions, simplifying ratios, solving problems using proportions and answering practice questions.

Blohowiak, Chad; Jensen, Douglas; Reed, Allen

2005-01-01

200

Improvements in Carrier-to-Noise-Ratio (CNR) of Lightwave Amplitude Modulated Vestigial-Sideband (AM-VSB) Transmission Systems by the Use of Optical Isolators  

NASA Astrophysics Data System (ADS)

In lightwave community antena television (CATV) systems as well as other optical fiber communication networks, a transmitted optical signal is known to be degraded by an intensity noise produced within the fiber due to the interference between the signal and doubly reflected light. We report on the improvements to the signal degradation due to the double Rayleigh backscattering by inserting optical isolators in the trunk lines of the systems. A carrier-to-noise ratio (CNR) has been calculated as a function of the number and the insertion loss of the isolators. The calculated results indicate that there is an optimum number of isolators, and if the insertion loss is less than 0.3 dB, the CNR degradation can be restored by more than 60%. To test the calculated results, we conducted experiments for the specific case of employing one isolator, and obtained good agreements between the two.

Takeo, Takashi; Kanie, Tomohiko; Satoh, Katsuhiro; Aoyama, Shigeyuki; Itoh, Haruhiko; Hattori, Hajime

1995-09-01

201

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

202

Varying [C II]/[N II] Line Ratios in the Interacting System BR1202-0725 at z = 4.7  

NASA Astrophysics Data System (ADS)

We study the properties of the interstellar medium in the interacting system BR1202-0725 at z = 4.7 via its [N II] and [C II] fine-structure line emission. This system consists of a QSO, a sub-mm galaxy (SMG), and two Ly? emitters (LAEs). Such a diversity in galaxy properties makes BR1202-0725 a unique laboratory of star formation and galaxy evolution at high redshift. We present ionized nitrogen ([N II] 205 ?m) observations of this system, obtained with the IRAM Plateau de Bure Interferometer. We find no [N II] emission at the quasar location, but tentative [N II] line detections associated with the SMG and one of the LAEs. Together with available ionized carbon ([C II] 158 ?m) Atacama Large Millimeter Array observations of this system, we find the following: the [C II]/[N II] luminosity ratio is >5.5 for the QSO and the SMG, but it is as low as ~2 in the LAE, suggesting that, in this source, most of the [C II] emission is associated with the ionized medium (H II regions) rather than the neutral one (photon-dominated regions). This study demonstrates the importance of combined studies of multiple fine-structure lines in order to pin down the physical properties of the interstellar medium in distant galaxies.

Decarli, R.; Walter, F.; Carilli, C.; Bertoldi, F.; Cox, P.; Ferkinhoff, C.; Groves, B.; Maiolino, R.; Neri, R.; Riechers, D.; Weiss, A.

2014-02-01

203

Determination of plutonium and its isotopic ratio in marine sediment samples using quadrupole ICP-MS with the shield torch system under normal plasma conditions.  

PubMed

An analytical method for determining (239)Pu and (240)Pu in marine sediment samples, which uses quadrupole ICP-MS, was developed in this work. A simple anion-exchange chromatography system was employed for the separation and purification of Pu from the sample matrix. A sufficient decontamination factor of 1.4 x 10(4) for U, which interferes with the determination of (239)Pu, was achieved. High sensitivity Pu determination was obtained, which led to an extremely low concentration detection limit of approximately 8 fg/ml (0.019 mBq/ml for (239)Pu; 0.071 mBq/ml for (240)Pu) in a sample solution, or an absolute detection limit of 42 fg in a 5 ml sample solution, by using the shield torch technique. Analytical results for the determination of the (239+240)Pu and the (240)Pu/(239)Pu ratio in IAEA 368 (ocean sediment) reference material indicated that the accuracy of the method was satisfactory. The method developed was successfully applied to a study of Pu behavior in the sediments from Sagami Bay, Japan. The observed high (240)Pu/(239)Pu ratio in the sediment core indicated that there was additional Pu input derived from close-in fallout in addition to the global fallout. PMID:15118798

Zheng, Jian; Yamada, Masatoshi; Wang, Zhongliang; Aono, Tatsuo; Kusakabe, Masashi

2004-06-01

204

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

205

Fingermark evidence evaluation based on automated fingerprint identification system matching scores: the effect of different types of conditioning on likelihood ratios.  

PubMed

In recent studies, the evidential value of the similarity of minutiae configurations of fingermarks and fingerprints, for example expressed by automated fingerprint identification systems (AFIS), is determined by likelihood ratios (LRs). The paper explores whether there is an effect on LRs if conditioning takes place on specified fingers, fingerprints, or fingermarks under competing hypotheses: In addition, an approach is explored where conditioning is asymmetric. Comparisons between fingerprints and simulated fingermarks with eight minutiae are performed to produce similarity score distributions for each type of conditioning, given a fixed AFIS matching algorithm. Both similarity scores and LRs are significantly different if the conditioning changes. Given a common-source scenario, "LRs" resulting from asymmetric conditioning are on average higher. The difference may reach a factor of 2000. As conditioning on a suspect's finger(print) is labor-intensive and requires a cooperating suspect, it is recommended to just condition on the number of minutiae in the fingermark. PMID:24180303

Alberink, Ivo; de Jongh, Arent; Rodriguez, Crystal

2014-01-01

206

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

207

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

208

Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration.  

PubMed

A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge. PMID:16936857

Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

2006-09-15

209

Steiner Ratio for Manifolds  

E-print Network

The Steiner ratio characterizes the greatest possible deviation of the length of a minimal spanning tree from the length of the minimal Steiner tree. In this paper, estimates of the Steiner ratio on Riemannian manifolds are obtained. As a corollary, the Steiner ratio for flat tori, flat Klein bottles, and projective plane of constant positive curvature are computed. Steiner ratio - Steiner problem - Gilbert--Pollack conjecture - surfaces of constant curvature

Cieslik, D; Tuzhilin, A A; 10.1023/A:1026106802540

2011-01-01

210

A variable-density fictitious-domain method for fully resolved simulation of high-density ratio fluid-particle systems  

NASA Astrophysics Data System (ADS)

A numerical scheme for fully resolved simulation of fluid-particle systems with freely moving rigid particles is developed. The approach is based on a fictitious domain method wherein the entire fluid-particle domain is assumed to be a fluid and the flow inside the particle domain is constrained to be a rigid body motion using an additional rigidity constraint in a three-stage fractional step scheme. The particle is assumed to be made up of material points moving on a fixed background mesh where the fluid flow equations are solved. The basic finite-volume solver is based on a co-located grid incompressible, but variable-density, flow. The incompressibility constraint is imposed by solving a variable-coefficient pressure equation giving rise to a stable scheme for high density ratio fluid-particle systems. This scheme is used to simulate a range of single and multiple particle problems in laminar flows. Application of the scheme for the simulation of large number of fully resolved particles in wall-bounded turbulent flows, such as those occur in sediment transport, will be discussed.

Apte, Sourabh

2008-11-01

211

230Th/232Th activity ratios as a chronological marker complementing 210Pb dating in an estuarine system affected by industrial releases.  

PubMed

The main purpose of this research is to show the usefulness of the 230Th/232Th activity ratios as a chronological marker that can be helpful in the dating of sediment cores collected from an estuarine system located in the south west of Spain highly polluted by wastes from fertilizer plants. These wastes, being released for 30 years, and enriched in radionuclides from the uranium series including 210Pb, invalidate the application of the 210Pb dating technique in full extent to the sediment cores collected in this estuary. However, the evaluation and the interpretation of both 210Pb and 230Th/232Th profiles allows the determination of average sedimentation rates in different parts of the cores, contaminated and noncontaminated zone, that agree in the case analysed in this research. Through this approach, a confident chronology covering the last century, which is essential to analyse and reconstruct the historical evolution of other pollutants in this heavily contaminated system can be established. PMID:11291442

San Miguel, E G; Bolívar, J P; García-Tenorio, R; Martín, J E

2001-01-01

212

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

213

Maximum ratio transmission  

Microsoft Academic Search

This paper presents the concept, principles, and analysis of maximum ratio transmission for wireless communications, where multiple antennas are used for both transmission and reception. The principles and analysis are applicable to general cases, including maximum-ratio combining. Simulation results agree with the analysis. The analysis shows that the average overall signal-to-mise ratio (SNR) is proportional to the cross correlation between

Titus K. Y. Lo

1999-01-01

214

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

215

Transformer ratio enhancement experiment  

Microsoft Academic Search

Recently, a multibunch scheme for efficient acceleration based on dielectric wakefield accelerator technology was outlined in ref.[1]. In this paper we present an experimental program for the design, development and demonstration of an Enhanced Transformer Ratio Dielectric Wakefield Accelerator (ETR-DWA). The principal goal is to increase the transformer ratio R, the parameter that characterizes the energy transfer efficiency from the

A. Kanareykin; Wei Gai; J. G. Power; E. Nenasheva; A. Altmark

2003-01-01

216

On savings ratio  

Microsoft Academic Search

This paper explores the factors that affect saving and consumption behaviours, in a context where some believe that the high savings ratio of the East Asia and oil-producing countries is one major cause for the global imbalances and the crisis. The paper elaborates on the factors behind the high savings ratios in East Asia and oil producing countries and low

Z. Xiaochuan

2011-01-01

217

Likelihood Ratio Tests  

NSDL National Science Digital Library

This page, created by Kyle Siegrist of the University of Alabama - Huntsville, introduces likelihood ratio tests by giving the Neyman-Pearson lemma and several examples. The examples include a gamma model, a binomial model, and a nonparametric model. The page concludes with a definition of the generalized likelihood ratio test.

Siegrist, Kyle

2009-01-12

218

Common ratio using delay  

Microsoft Academic Search

We present an experiment in which we add a common delay in a choice between two risky prospects. The results show that delay\\u000a produces the same change in preferences as in the well-documented common ratio effect in risky lotteries. The added common\\u000a delay acts as if the probabilities were divided by some common ratio. Moreover, we show that there is

Manel Baucells; Franz H. Heukamp

2010-01-01

219

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

220

Is that really your Strehl ratio?  

Microsoft Academic Search

Strehl ratio is the most commonly used metric for adaptive optics (AO) performance. It is also the most misused metric. Every Strehl ratio measurement algorithm has subtle differences that result in different measured values. This creates problems when comparing different measurements of the same AO system and even more problems when trying to compare results from different systems. To determine

Lewis C. Roberts Jr.; Marshall D. Perrin; Franck Marchis; Anand Sivaramakrishnan; Russell B. Makidon; Julian C. Christou; Bruce A. Macintosh; Lisa A. Poyneer; Marcos A. van Dam; Mitchell Troy

2004-01-01

221

Does body size of dairy cows, at constant ratio of maintenance to production requirements, affect productivity in a pasture-based production system?  

PubMed

This study compared productivity of dairy cows with different body weight (BW), but a constant ratio of maintenance to production requirements in their first lactation, in a pasture-based production system with spring calving. Two herds, Herd L (13 and 14 large cows in 2003 and 2004 respectively; average BW after calving, 721 kg) and Herd S (16 small cows in both years; 606 kg) [Correction added after online publication 14 January 2011: 16 small cows in both years; 621 kg was changed to 16 small cows in both years; 606 kg], all in their second or following lactations, were each allocated 6 ha of pasture and rotationally grazed on 10 parallel paddocks with equal herbage offer and nutritional values. Winter hay, harvested from the same pastures, was offered ad libitum in the indoor periods in a tied stall barn. Each herd received, per lactation and year, approximately 2000 kg dry matter (DM) of concentrates and of fodder beets, equally distributed to every individual. Indoors, the L-cows ingested more DM than the S-cows (18.7 vs. 16.3 kg DM/cow per day; p < 0.01), but DM intake per 100 kg of metabolic BW was similar (13.0 vs. 13.1 kg DM/cow per day). Estimates based on the n-alkane technique gave similar results on pasture (17.9 vs. 15.5 kg DM/cow per day; p < 0.001). Roughage intakes per 100 kg of metabolic BW, at 13.5 kg DM/cow per day, were similar. Mean annual yield of energy-corrected milk (ECM)/ha was slightly higher for the S-herd than the L-herd (13,026 vs. 12,284 kg) but was associated with a higher stocking rate (on average +20%) for the S-herd. Feed conversion efficiency (1.2 vs. 1.3 kg ECM/kg DM intake) and overall milk production efficiency (45.3 vs. 47.3 kg ECM/kg metabolic BW) were similar in L- and S-cows. Thus, both dairy cow types were equally efficient in utilising pasture-based forage. PMID:21114551

Hofstetter, P; Steiger Burgos, M; Petermann, R; Münger, A; Blum, J W; Thomet, P; Menzi, H; Kohler, S; Kunz, P

2011-12-01

222

The golden ratio autocorrelation function  

E-print Network

On the base of the recurrence relation formalism an autocorrelation function is obtained, the continued fraction form of which corresponds to the golden ratio ones. It turns out that this GR autocorrelation is known in science and obeys all necessary conditions, in contrast to the exponential autocorrelation function. Using the Kubo approach it is shown how exponential correlations appear in the linear response theory as a result on non-Hermitian relaxation of the system.

R. Tsekov

2014-02-10

223

Air/fuel ratio regulator  

SciTech Connect

A description is given of an air/fuel ratio regulator for use with the fuel injection control system of an internal combustion engine of the spark ignition type having an air and exhaust gas (gas) induction passage open at one end to air at ambient pressure level and connected at its other end to the engine combustion chamber to be subject to manifold vacuum changes therein, a throttle valve rotatably mounted for movement across the passage to control the gas flow therethrough, exhaust gas recirculation (egr) passage means connecting engine exhaust gases to the induction passage above the closed position of the throttle valve, an egr flow control valve mounted in the egr passage means for movement between open and closed postions to control the volume of egr gas flow, an engine speed responsive positive displacement type fuel injection pump having a fuel flow output to the engine that varies in direct proportion to changes in engines speed to match fuel flow and mass airflow through the induction system of the engine over the entire speed and load range of the engine to maintain the intake mixture ratio of air to fuel constant, the pump having a fuel flow control lever movable to vary the fuel rate of flow, the regulator being characterized by engine manifold vacuum responsive first servo means operably connected to the fuel control lever for maintaining a constant air/fuel (A/F) ratio by changing fuel output as a function of changing manifold vacuum and air flow upon opening of the throttle valve, a fuel enrichment control lever operably connected to the pump control lever and movable to modify the position of the pump lever dictated by the first servo means to change the A/F ratio, and further means responsive to engine operating conditions for moving the fuel enrichment control lever to provide the changed A/F ratio.

Simko, A.

1980-07-22

224

The Golden Ratio  

NSDL National Science Digital Library

This Web site provides a basic introduction to one of the most amazing discoveries in mathematics: the Golden Ratio. Created by David L. Narain, this site offers a particularly engaging way to bring together math and the natural sciences in the classroom. Seven straightforward activities have students construct a golden rectangle and spiral, and also explore the Golden Ratio in nature and in other contexts. The site also includes a quiz; answers are not provided, though. The activities are designed for 9th and 10th graders, but would also be appropriate for middle school students.

Narain, David L.

2001-01-01

225

288 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 9, NO. 3, SEPTEMBER 2000 High Aspect-Ratio Combined Poly and Single-Crystal  

E-print Network

of such a technology improves long-term stability and temperature sensitivity. Hundreds of micrometers thick silicon long-term stability and temperature sensitivity, while fabrication of large-area vertical pickoff-Ratio Combined Poly and Single-Crystal Silicon (HARPSS) MEMS Technology Farrokh Ayazi, Member, IEEE, and Khalil

226

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

2009-01-08

227

Digit ratio in birds.  

PubMed

The Homeobox (Hox) genes direct the development of tetrapod digits. The expression of Hox genes may be influenced by endogenous sex steroids during development. Manning (Digit ratio. New Brunswick, NJ: Rutgers University Press, 2002) predicted that the ratio between the lengths of digits 2 (2D) and 4 (4D) should be sexually dimorphic because prenatal exposure to estrogens and androgens positively influence the lengths of 2D and 4D, respectively. We measured digits and other morphological traits of birds from three orders (Passeriformes, house sparrow, Passer domesticus; tree swallow, Tachycineta bicolor; Pscittaciformes, budgerigar, Melopsittacus undulates; Galliformes, chicken, Gallus domesticus) to test this prediction. None were sexually dimorphic for 2D:4D and there were no associations between 2D:4D and other sexually dimorphic traits. When we pooled data from all four species after we averaged right and left side digits from each individual and z-transformed the resulting digit ratios, we found that males had significantly larger 2D:4D than did females. Tetrapods appear to be sexually dimorphic for 2D:4D with 2D:4D larger in males as in some birds and reptiles and 2D:4D smaller in males as in some mammals. The differences between the reptile and mammal lineages in the directionality of 2D:4D may be related to the differences between them in chromosomal sex determination. We suggest that (a) natural selection for a perching foot in the first birds may have overridden the effects of hormones on the development of digit ratio in this group of vertebrates and (b) caution be used in making inferences about prenatal exposure to hormones and digit ratio in birds. PMID:18833568

Lombardo, Michael P; Thorpe, Patrick A; Brown, Barbara M; Sian, Katie

2008-12-01

228

Pyrolaser Operating System  

NASA Technical Reports Server (NTRS)

Software provides for control and acquisition of data from optical pyrometer. There are six individual programs in PYROLASER package. Provides quick and easy way to set up, control, and program standard Pyrolaser. Temperature and emisivity measurements either collected as if Pyrolaser in manual operating mode or displayed on real-time strip charts and stored in standard spreadsheet format for posttest analysis. Shell supplied to allow macros, which are test-specific, added to system easily. Written using Labview software for use on Macintosh-series computers running System 6.0.3 or later, Sun Sparc-series computers running Open-Windows 3.0 or MIT's X Window System (X11R4 or X11R5), and IBM PC or compatible computers running Microsoft Windows 3.1 or later.

Roberts, Floyd E., III

1994-01-01

229

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

230

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

231

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 "GoosebumpsâMonster Blood III" (Chapters 15 and 16) by R.L. Stine, or "The Shrinking of Treehorn" by F. Heide.

2003-01-01

232

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; Rosz, John

2011-04-05

233

Ratio Word Problems  

NSDL National Science Digital Library

This lesson begins with a word problem in which students must figure how much money Erica and Tim each earn when they split $480 by a ratio of 5:3. After the problem, students watch a video in which the problem is solved using division and multiplication and again using fractions. Students then click the Try It button to complete a problem on their own. There are also embedded tools, a calculator and scratchpad, for students to use as they solve.

2006-01-01

234

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.

Jensen, Douglas; Reed, Allen

2005-01-01

235

Measurement of ? branching ratios  

NASA Astrophysics Data System (ADS)

We have measured the branching ratios for several ? decay modes. We use e+e--->?+?- events accumulated with the TPC/Two-Gamma facility at the SLAC e+e- storage ring PEP. The data correspond to an integrated luminosity of 77 pb-1 at a center-of-mass energy of 29 GeV. The one- and three-charged-particle inclusive branching ratios of the ? decay are measured to be B1=(84.7+/-1.0)% and B3=(15.1+/-1.0)%, where B1+B3 is constrained to be 99.85%. The branching ratios of the two leptonic decay modes are B(?--->e- ?¯e??)=(18.4+/-1.6)% and B(?--->?- ?¯???)=(17.7+/-1.4)%. If we then assume lepton universality, we obtain B(?--->e- ?¯e??)=(18.3+/-0.9)% and B(?--->?- ?¯???)=(17.8+/-0.9)%. We measure the Cabibbo-allowed semihadronic decay mode B(?--->?-+neutral particles)=(47.0+/-1.5)%, and the Cabibbo-suppressed ? decay mode B(?--->K-+neutral particles)=(1.6+/-0.4)%. By looking for associated photons, we find B(?--->K-?0+neutral particles) to be (1.2+/-0.6)%. Using the channel K*--->KOS?+?-, we find B(?--->K*-(892)+neutral particles)=(1.4+/-0.9)%. The quoted errors are the combined statistical and systematic errors.

Aihara, H.; Alston-Garnjost, M.; Avery, R. E.; Bakken, J. A.; Barbaro-Galtieri, A.; Barker, A. R.; Barnes, A. V.; Barnett, B. A.; Barnett, B. A.; Bauer, D. A.; Bengtsson, H.-U.; Bintinger, D. L.; Bobbink, G. J.; Bolognese, T. S.; Bross, A. D.; Buchanan, C. D.; Buijs, A.; Caldwell, D. O.; Chien, C.-Y.; Clark, A. R.; Cowan, G. D.; Crane, D. A.; Dahl, O. I.; Derby, K. A.; Eastman, J. J.; Edberg, T. K.; Eberhard, P. H.; Eisner, A. M.; Enomoto, R.; Erné, F. C.; Fujii, T.; Gary, J. W.; Gorn, W.; Hauptman, J. M.; Hofmann, W.; Huth, J. E.; Hylen, J.; Kamae, T.; Kaye, H. S.; Kees, K. H.; Kenney, R. W.; Kerth, L. T.; Ko, Winston; Koda, R. I.; Kofler, R. R.; Kwong, K. K.; Lander, R. L.; Langeveld, W. G.; Layter, J. G.; Linde, F. L.; Lindsey, C. S.; Loken, S. C.; Lu, A.; Lu, X.-Q.; Lynch, G. R.; Madansky, L.; Madaras, R. J.; Maeshima, K.; Magnuson, B. D.; Marx, J. N.; Masek, G. E.; Mathis, L. G.; Matthews, J. A.; Maxfield, S. J.; Melnikoff, S. O.; Miller, E. S.; Moses, W.; McNeil, R. R.; Nemethy, P.; Nygren, D. R.; Oddone, P. J.; Paar, H. P.; Park, D. A.; Park, S. K.; Pellett, D. E.; Pevsner, A.; Pripstein, M.; Ronan, M. T.; Ross, R. R.; Rouse, F. R.; Schwitkis, K. A.; Sens, J. C.; Shapiro, G.; Shapiro, M. D.; Shen, B. C.; Slater, W. E.; Smith, J. R.; Steinman, J. S.; Stevenson, M. L.; Stork, D. H.; Strauss, M. G.; Sullivan, M. K.; Takahashi, T.; Thompson, J. R.; Toge, N.; Toutounchi, S.; van Tyen, R.; van Uitert, B.; Vandalen, G. J.; van Daalen Wetters, R. F.; Vernon, W.; Wagner, W.; Wang, E. M.; Wang, Y. X.; Wayne, M. R.; Wenzel, W. A.; White, J. T.; Williams, M. C.; Wolf, Z. R.; Yamamoto, H.; Yellin, S. J.; Zeitlin, C.; Zhang, W.-M.

1987-03-01

236

Effects of speckle/pixel size ratio on temporal and spatial speckle-contrast analysis of dynamic scattering systems: Implications for measurements of blood-flow dynamics  

PubMed Central

Laser Speckle Contrast Imaging (LSCI) is an optical technique used to generate blood flow maps with high spatial and temporal resolution. It is well known that in LSCI, the speckle size must exceed the Nyquist criterion to maximize the speckle's pattern contrast. In this work, we study experimentally the effect of speckle-pixel size ratio not only in dynamic speckle contrast, but also on the calculation of the relative flow speed for temporal and spatial analysis. Our data suggest that the temporal LSCI algorithm is more accurate at assessing the relative changes in flow speed than the spatial algorithm. PMID:24156051

Ramirez-San-Juan, J. C.; Mendez-Aguilar, E.; Salazar-Hermenegildo, N.; Fuentes-Garcia, A.; Ramos-Garcia, R.; Choi, B.

2013-01-01

237

Effects of speckle/pixel size ratio on temporal and spatial speckle-contrast analysis of dynamic scattering systems: Implications for measurements of blood-flow dynamics.  

PubMed

Laser Speckle Contrast Imaging (LSCI) is an optical technique used to generate blood flow maps with high spatial and temporal resolution. It is well known that in LSCI, the speckle size must exceed the Nyquist criterion to maximize the speckle's pattern contrast. In this work, we study experimentally the effect of speckle-pixel size ratio not only in dynamic speckle contrast, but also on the calculation of the relative flow speed for temporal and spatial analysis. Our data suggest that the temporal LSCI algorithm is more accurate at assessing the relative changes in flow speed than the spatial algorithm. PMID:24156051

Ramirez-San-Juan, J C; Mendez-Aguilar, E; Salazar-Hermenegildo, N; Fuentes-Garcia, A; Ramos-Garcia, R; Choi, B

2013-01-01

238

Use of VNIR Camera System to Estimate Lava Temperature  

NASA Astrophysics Data System (ADS)

We present initial results from using a visible and near infrared (VNIR) camera as an optical pyrometer at Kilauea Volcano, Hawai`i. The basic concept of pyrometry simply converts the color of incandescent material into a temperature and has been used on Kilauea since the earliest days of regular volcano monitoring. However, these temperatures have always been lower than expected, raising the concern that the emissivity of lava at these wavelengths was not close to a blackbody. We carefully calibrated a system that uses 3 digital cameras with wavelengths similar to the green, red, and near-infrared channels of the Landsat Enhanced Thematic Mapper plus (ETM+) and Advanced Spaceborne Thermal Emissions and Reflection Radiometer (ASTER) VNIR instruments by imaging a high-temperature blackbody. Following techniques used to estimate lava temperatures on Jupiter's moon, Io, we obtained relationships between band ratios and blackbody temperatures. The green/red ratio provides good temperature estimates for any reasonable temperature above 1000 °C, while the red/NIR is useful from about 700-1200 °C. We also observed the glow from the lava lake in Halema`uma`u as reflected and scattered from the steam plume above it. We found that the temperatures inferred from the glow are much too high (~1400 °C) from the red/NIR ratios and much too low (<700 °C) from the green/red ratios. One possible explanation is that there are variations in the emissivity of molten lava at these wavelengths. However, we also know that there are wavelength dependent scattering properties of the plume cloud that are consistent with errors in these temperature estimates. Future work examining incandescent lava without the interference of a plume will be needed to better evaluate the emissivity of lava in this wavelength range. However, we have sufficient data to demonstrate the great utility of VNIR data acquired at night for determining if a volcano is actively erupting mafic lava. We propose that further refinement of this methodology using ETM+, ASTER, and other instruments could provide a useful complement to other near-real-time thermal alert systems.

Vaughan, R.; Keszthelyi, L. P.

2012-12-01

239

High-response on-line gas analysis system for hydrogen-reaction combustion products  

NASA Technical Reports Server (NTRS)

The results of testing an on-line quadrupole gas analyzer system are reported. Gas samples were drawn from the exhaust of a hydrogen-oxygen-nitrogen rocket which simulated the flow composition and dynamics at the combustor exit of a supersonic combustion ramjet engine. System response time of less than 50 milliseconds was demonstrated, with analytical accuracy estimated to be + or - 5 percent. For more complex chemical systems with interfering atom patterns, analysis would be more difficult. A cooled-gas pyrometer probe was evaluated as a total temperature indicator and as the primary mass flow measuring element for the total sample flow rate.

Metzler, A. J.; Gaugler, R. E.

1974-01-01

240

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.

Herrera, Terese

2006-06-01

241

The midbrain to pons ratio  

PubMed Central

Objectives: MRI-based measurements used to diagnose progressive supranuclear palsy (PSP) typically lack pathologic verification and are not easy to use routinely. We aimed to develop in histologically proven disease a simple measure of the midbrain and pons on sagittal MRI to identify PSP. Methods: Measurements of the midbrain and pontine base on midsagittal T1-weighted MRI were performed in confirmed PSP (n = 12), Parkinson disease (n = 2), and multiple system atrophy (MSA) (n = 7), and in controls (n = 8). Using receiver operating characteristic curve analysis, cutoff values were applied to a clinically diagnosed cohort of 62 subjects that included PSP (n = 21), Parkinson disease (n = 10), MSA (n = 10), and controls (n = 21). Results: The mean midbrain measurement of 8.1 mm was reduced in PSP (p < 0.001) with reduction in the midbrain to pons ratio (PSP smaller than MSA; p < 0.001). In controls, the mean midbrain ratio was approximately two-thirds of the pontine base, in PSP it was <52%, and in MSA the ratio was greater than two-thirds. A midbrain measurement of <9.35 mm and ratio of 0.52 had 100% specificity for PSP. In the clinically defined group, 19 of 21 PSP cases (90.5%) had a midbrain measurement of <9.35 mm. Conclusions: We have developed a simple and reliable measurement in pathologically confirmed disease based on the topography of atrophy in PSP with high sensitivity and specificity that may be a useful tool in the clinic. PMID:23616165

Massey, Luke A.; Jager, Hans R.; Paviour, Dominic C.; O'Sullivan, Sean S.; Ling, Helen; Williams, David R.; Kallis, Constantinos; Holton, Janice; Revesz, Tamas; Burn, David J.; Yousry, Tarek; Lees, Andrew J.; Fox, Nick C.; Micallef, Caroline

2013-01-01

242

Mass balance of pharmaceutical and personal care products in a pilot-scale single-sludge system: influence of T, SRT and recirculation ratio.  

PubMed

The influence of operation condition on the fate of 16 pharmaceutical and personal care products (PPCPs) in a single-sludge nitrifying/denitrifying pilot plant was assessed. Volatilisation, sorption and degradation were included in the mass balances to determine the most relevant removal mechanisms during PPCP treatment. Sludge retention time (SRT) was an important factor for the removal of compounds that significantly sorb onto sludge, as ethinylestradiol, whose removal increased 11% when working at SRT above 20 d. The internal recirculation ratio was significant for the removal of moderately biodegradable compounds, as citalopram. The positive effect of operating at warmer temperatures was particularly significant for two antibiotics, implying a 30% increase in their transformations. In the case of naproxen, an influence of sludge acclimation and concentration was observed, leading to removal efficiencies from 27% to 99%. Concerning removal mechanisms, most compounds were removed due to biotransformation, although for fragrances sorption and volatilisation played a role. PMID:22732303

Suárez, Sonia; Reif, Rubén; Lema, Juan M; Omil, Francisco

2012-09-01

243

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

244

The sources and evolution of mineralising fluids in iron oxide–copper–gold systems, Norrbotten, Sweden: Constraints from Br\\/Cl ratios and stable Cl isotopes of fluid inclusion leachates  

Microsoft Academic Search

We have analysed the halogen concentrations and chlorine stable isotope composition of fluid inclusion leachates from three spatially associated Fe-oxide±Cu±Au mineralising systems in Norrbotten, Sweden. Fluid inclusions in late-stage veins in Fe-oxide–apatite deposits contain saline brines and have a wide range of Br\\/Cl molar ratios, from 0.2 to 1.1×10?3 and ?37Cl values from ?3.1‰ to ?1.0‰. Leachates from saline fluid

S. A. Gleeson; M. P. Smith

2009-01-01

245

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

246

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

247

Trace ratio problem revisited.  

PubMed

Dimensionality reduction is an important issue in many machine learning and pattern recognition applications, and the trace ratio (TR) problem is an optimization problem involved in many dimensionality reduction algorithms. Conventionally, the solution is approximated via generalized eigenvalue decomposition due to the difficulty of the original problem. However, prior works have indicated that it is more reasonable to solve it directly than via the conventional way. In this brief, we propose a theoretical overview of the global optimum solution to the TR problem via the equivalent trace difference problem. Eigenvalue perturbation theory is introduced to derive an efficient algorithm based on the Newton-Raphson method. Theoretical issues on the convergence and efficiency of our algorithm compared with prior literature are proposed, and are further supported by extensive empirical results. PMID:19304481

Jia, Yangqing; Nie, Feiping; Zhang, Changshui

2009-04-01

248

Mining Adaptive Ratio Rules from Distributed Data Sources  

Microsoft Academic Search

Different from traditional association-rule mining, a new paradigm called Ratio Rule (RR) was proposed recently. Ratio rules are aimed at capturing the quantitative association knowledge, We extend this framework to mining ratio rules from distributed and dynamic data sources. This is a novel and challenging problem. The traditional techniques used for ratio rule mining is an eigen-system analysis which can

Jun Yan; Ning Liu; Qiang Yang; Benyu Zhang; Qiansheng Cheng; Zheng Chen

2006-01-01

249

Fascicular ratio: a new parameter to evaluate peripheral nerve pathology on magnetic resonance imaging: a feasibility study on a 3T MRI system.  

PubMed

The objective of the study was to define and quantitatively evaluate the fascicular ratio (FR) on magnetic resonance imaging (MRI) in patients with peripheral neuropathies compared with healthy controls. Forty control subjects (20 women, 20 men; age, 44.6?±?13.4 years) and 40 patients with peripheral neuropathy (22 women, 18 men; age, 50.3?±?10.2 years) were examined with a standard 3T MRI protocol. With customized software (with semiautomatic and automatic interface), the hypointense and hyperintense areas of the peripheral nerves corresponding to fascicular and nonfascicular tissue were examined on T1-weighted sequences. The ratio of fascicular pixels to total pixels was called FR. Correlation with FR calculated on high-resolution ultrasound was performed. The statistical analysis included the Mann-Whitney U test of controls versus patients, the receiver operating characteristic (ROC) analysis, and the subgroup analysis of patients according to etiologies of neuropathy. Intraobserver and interobserver agreement was calculated based on the evaluation made by 3 readers. Finally, a complete automatic evaluation was performed. On MRI, FRs were significantly increased in patients compared with controls (FR, 76.7?±?15.1 vs 56?±?12.3; P?

Tagliafico, Alberto S; Tagliafico, Giulio

2014-09-01

250

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

251

Low speed test of a high-bypass-ratio propulsion system with an asymmetric inlet designed for a tilt-nacelle V/STOL airplane  

NASA Technical Reports Server (NTRS)

A large scale model of a lift/cruise fan inlet designed for a tilt nacelle V/STOL airplane was tested with a high bypass ratio turbofan. Testing was conducted at low freestream velocities with inlet angles of attack ranging from 0 deg to 120 deg. The operating limits for the nacelle were found to be related to inlet boundary layer separation. Small separations originating in the inlet diffuser cause little or no performance degradation. However, at sufficiently severe freestream conditions the separation changes abruptly to a lip separation. This change is associated with a significant reduction in nacelle net thrust as well as a sharp increase in fan blade vibratory stresses. Consequently, the onset of lip separation is regarded as the nacelle operating limit. The test verified that the asymmetric inlet design will provide high performance and stable operation at the design forward speed and angle of attack conditions. At some of these, however, operation near the lower end of the design inlet airflow range is not feasible due to the occurrence of lip separation.

Syberg, J.

1978-01-01

252

Prognostic Significance of Systemic Inflammation-Based Lymphocyte- Monocyte Ratio in Patients with Lung Cancer: Based on a Large Cohort Study  

PubMed Central

Increasing evidence indicates cancer-related inflammatory biomarkers show great promise for predicting the outcome of cancer patients. The lymphocyte- monocyte ratio (LMR) was demonstrated to be independent prognostic factor mainly in hematologic tumor. The aim of the present study was to investigate the prognostic value of LMR in operable lung cancer. We retrospectively enrolled a large cohort of patients with primary lung cancer who underwent complete resection at our institution from 2006 to 2011. Inflammatory biomarkers including lymphocyte count and monocyte count were collected from routinely performed preoperative blood tests and the LMR was calculated. Survival analyses were calculated for overall survival (OS) and disease-free survival (DFS). A total of 1453 patients were enrolled in the study. The LMR was significantly associated with OS and DFS in multivariate analyses of the whole cohort (HR?=?1.522, 95% CI: 1.275–1.816 for OS, and HR?=?1.338, 95% CI: 1.152–1.556 for DFS). Univariate subgroup analyses disclosed that the prognostic value was limited to patients with non-small-cell lung cancer (NSCLC) (HR: 1.824, 95% CI: 1.520–2.190), in contrast to patients with small cell lung cancer (HR: 1.718, 95% CI: 0.946–3.122). Multivariate analyses demonstrated that LMR was still an independent prognostic factor in NSCLC. LMR can be considered as a useful independent prognostic marker in patients with NSCLC after complete resection. This will provide a reliable and convenient biomarker to stratify high risk of death in patients with operable NSCLC. PMID:25275631

Hu, Pingping; Shen, Hongchang; Wang, Guanghui; Zhang, Ping; Liu, Qi; Du, Jiajun

2014-01-01

253

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 derived from low-resolution (R {approx} 2000) spectra of 17,277 G-type dwarfs from the SEGUE survey to separate them into likely thin- and thick-disk subsamples. Both subsamples exhibit strong gradients of orbital rotational velocity with metallicity, of opposite signs, -20 to -30 km s{sup -1} dex{sup -1} for the thin-disk and +40 to +50 km s{sup -1} dex{sup -1} for the thick-disk population. The rotational velocity is uncorrelated with Galactocentric distance for the thin-disk subsample and exhibits a small trend for the thick-disk subsample. The rotational velocity decreases with distance from the plane for both disk components, with similar slopes (-9.0 {+-} 1.0 km s{sup -1} kpc{sup -1}). Thick-disk stars exhibit a strong trend of orbital eccentricity with metallicity (about -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 population, while a marginal gradient of the eccentricity with radius exists for the thick-disk population. Both subsamples possess similar positive gradients of eccentricity with distance from the Galactic plane. The shapes of the eccentricity distributions for the thin- and thick-disk populations are independent of distance from the plane, and include no significant numbers of stars with eccentricity above 0.6. Among several contemporary models of disk evolution that we consider, radial migration appears to have played an important role in the evolution of the thin-disk population, but possibly less so for the thick disk, relative to the gas-rich merger or disk heating scenarios. We emphasize that more physically realistic models and simulations need to be constructed in order to carry out the detailed quantitative comparisons that our new data enable.

Lee, Young Sun; Beers, Timothy C. [Department of Physics and Astronomy and JINA (Joint Institute for Nuclear Astrophysics), Michigan State University, East Lansing, MI 48824 (United States); An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Ivezic, Zeljko [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Just, Andreas [Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg (ZAH), Moenchhofstr. 12-14, 69120 Heidelberg (Germany); Rockosi, Constance M. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Morrison, Heather L.; Harding, Paul [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States); Johnson, Jennifer A.; Bird, Jonathan [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States); Schoenrich, Ralph [Max-Planck-Institute fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Yanny, Brian [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Rocha-Pinto, Helio J., E-mail: lee@pa.msu.edu, E-mail: beers@pa.msu.edu [Universidade Federal do Rio de Janeiro, Observatorio do Valongo, Lad. Pedro Antonio 43, 20080-090 Rio de Janeiro (Brazil)

2011-09-10

254

Elucidating the mechanisms of protein antigen adsorption to the CAF/NAF liposomal vaccine adjuvant systems: effect of charge, fluidity and antigen-to-lipid ratio.  

PubMed

The reverse vaccinology approach has recently resulted in the identification of promising protein antigens, which in combination with appropriate adjuvants can stimulate customized, protective immune responses. Although antigen adsorption to adjuvants influences vaccine efficacy and safety, little is generally known about how antigens and adjuvants interact at the molecular level. The aim of this study was to elucidate the mechanisms of interactions between the equally sized, but oppositely charged model protein antigens ?-lactalbumin and lysozyme, and i) the clinically tested cationic liposomal adjuvant CAF01 composed of cationic dimethyldioctadecylammonium (DDA) bromide and trehalose-6,6'-dibehenate (TDB) or ii) the neutral adjuvant formulation NAF01, where DDA was replaced with zwitterionic distearoylphosphatidylcholine (DSPC). The effect of liposome charge, bilayer rigidity, isoelectric point and antigen-to-lipid ratio was investigated using dynamic light scattering, transmission electron microscopy, differential scanning calorimetry, intrinsic fluorescence and Langmuir monolayers. The net anionic ?-lactalbumin adsorbed onto the cationic liposomes, while there was no measureable attractive interaction with the zwitterionic liposomes. In contrast, the net cationic lysozyme showed very little interaction with either types of liposome. Adsorption of ?-lactalbumin altered its tertiary structure, affected lipid membrane packing below and above the phase transition temperature, and neutralized the liposomal surface charge, resulting in reduced colloidal stability and liposome aggregation. Langmuir studies revealed that ?-lactalbumin was not squeezed out of DDA monolayers upon compression, which suggests additional hydrophobic interactions. Such interactions are thus likely to affect the way vaccine antigens are presented to antigen-presenting cells, and may play an important role for the efficacy of the vaccine-induced immune response. These studies thus exemplify the importance of characterizing the molecular interactions between the vaccine antigen and adjuvant along with immunogenicity and efficacy studies. PMID:24769435

Hamborg, Mette; Rose, Fabrice; Jorgensen, Lene; Bjorklund, Katrine; Pedersen, Helene B; Christensen, Dennis; Foged, Camilla

2014-08-01

255

Streak camera-TV system with improved S/N ratio incorporating a digital video recorder directly interfaced to a computer.  

PubMed

By incorporating a digital video recorder, a streak camera system previously developed for recording time-resolved transient absorption and emission spectra was greatly improved with respect to reproducibility and accuracy. The requirements for on-line computer time were also reduced. PMID:18699459

Schmidt, K H; Gordon, S

1979-12-01

256

Note on the Odds Ratio and the Probability Ratio  

Microsoft Academic Search

This note compares the odds ratio with the probability ratio (relative risk). These quantities arise, for example, in the analysis of educational and social science data by means of logistic regression.

Michael P. Cohen

2000-01-01

257

Effect of exhaust nozzle configuration on aerodynamic and acoustic performance of an externally blown flap system with a quiet 6:1 bypass ratio engine  

NASA Technical Reports Server (NTRS)

A highly suppressed TF-34 engine was used to investigate engine and flap interaction noise associated with an externally blown flap STOL powered lift system. Noise, efficiency, and velocity decay characteristics of mixed and separate flow exhaust systems including convergent, co-annular, and lobed designs were determined with the engine operating alone. Noise data were then obtained for several of the exhaust configurations with the engine blowing a wing-flap segment. Noise for both the engine alone and the engine with blown flaps showed substantial differences for the various exhaust configurations tested. The differences in observed noise are related primarily to nozzle effective exhaust velocity, flap impingement velocity, and noise spectral shape.

Samanich, N. E.; Heidelberg, L. J.; Jones, W. L.

1973-01-01

258

Cleavage of the antitoxin of the parD toxin-antitoxin system is determined by the ClpAP protease and is modulated by the relative ratio of the toxin and the antitoxin.  

PubMed

Differential stability of toxins and antitoxins is the key for the conditional activation and function of Toxin-Antitoxin systems. Here we report the evaluation of the action of cell proteases Lon, ClpAP, ClpXP and ClpYQ on the Kis antitoxin and the Kid toxin of the parD TA system of plasmid R1. In vitro analysis shows that Kis antitoxin, but not the Kid toxin, is cleaved specifically by the ClpAP protease. The Kid toxin is not cleaved either by this protease or by any of the others cell proteases tested but in complex with the Kis antitoxin protects the cleavage of this protein in a way that is dependent on the toxin-antitoxin ratio. We further show that this protection is correlated with the inability of the ClpA chaperone to access the Kis antitoxin when in complex with Kid toxin. The stability of the antitoxin greatly increases in vivo in a clpP- background and plasmid maintenance mediated by the parD system, which is dependent on the differential decay of the antitoxin, is reduced to the levels observed in the absence of a functional toxin. The functional implications of these data are further discussed within the frame of the regulation of the parD system and of the available information on the nature of the toxin-antitoxin complexes formed at different toxin-antitoxin ratios. PMID:23419648

Diago-Navarro, Elizabeth; Hernández-Arriaga, Ana María; Kubik, Slawomir; Konieczny, Igor; Díaz-Orejas, Ramón

2013-07-01

259

Controlling Gas-Flow Mass Ratios  

NASA Technical Reports Server (NTRS)

Proposed system automatically controls proportions of gases flowing in supply lines. Conceived for control of oxidizer-to-fuel ratio in new gaseous-propellant rocket engines. Gas-flow control system measures temperatures and pressures at various points. From data, calculates control voltages for electronic pressure regulators for oxygen and hydrogen. System includes commercially available components. Applicable to control of mass ratios in such gaseous industrial processes as chemical-vapor depostion of semiconductor materials and in automotive engines operating on compressed natural gas.

Morris, Brian G.

1990-01-01

260

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

261

Usefulness of the organ culture system when villous height/crypt depth ratio, intraepithelial lymphocyte count, or serum antibody tests are not diagnostic for celiac disease.  

PubMed

The existence of mild forms of celiac disease (CD) can make the histology-based diagnosis difficult to reach. Since anti-endomysium (EMA) and anti-tissue transglutaminase (anti-tTG) are detectable in culture supernatants of duodenal biopsies from CD patients, our aim was to assess if this system can support the histology in the diagnostic work-up. A total of 559 suspected CD patients underwent serum EMA/anti-tTG detection, upper endoscopy with duodenal biopsy sampling, histologic analysis, and organ culture to detect EMA/anti-tTG in supernatants. A subgroup of 30 patients with organ culture positive results were put on a gluten-free diet (GFD). Their gluten-dependency was evaluated by the psychological general well-being and beck depression inventory indexes. Statistical analysis was performed by Cohen k inter-test, Friedman test, and Dunn multiple comparison. Two hundred forty-one out of 559 (43.1%) patients showed intestinal villous atrophy, whereas serum and organ culture EMA/anti-tTG were positive in 293/559 (52.4%) and 334/559 (59.7%) patients, respectively. The strength of agreement resulted good for serology vs histology (k = 0.730), good for organ culture vs histology (k = 0.662), and very good for serology vs organ culture (k = 0.852). After 12 months of GFD, psychological general well-being index significantly increased, and beck depression inventory index significantly decreased (P < 0.001 for each one). Data highlight the organ culture system as a useful tool to assist the histology in diagnosing CD, mainly in cases without villous atrophy or in seronegative patients. The marked improvement in quality of life after a GFD further supports the reliability of this system in diagnosing CD. PMID:23177794

Picarelli, Antonio; Di Tola, Marco; Marino, Mariacatia; Libanori, Valerio; Borghini, Raffaele; Salvi, Elisa; Donato, Giuseppe; Vitolo, Domenico; Tiberti, Antonio; Marcheggiano, Adriana; Bassotti, Gabrio; Corazziari, Enrico

2013-03-01

262

Strehl ratio and aberration balancing  

Microsoft Academic Search

The relation between the Strehl ratio and the wave-front variance is analyzed from the point of view of aberration balancing. For some given set of aberrations the Strehl ratio is calculated along two different parametric paths in the aberration space: one corresponding to the minimum wave-front variance and the other to the maximum Strehl ratio. The case of the combination

Geiser Martial

1991-01-01

263

The effect of SiO?/Al?O? ratio on the structure and microstructure of the glazes from SiO?-Al?O?-CaO-MgO-Na?O-K?O system.  

PubMed

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 SiO?/Al?O?. In this work the six composition of glazes from SiO?-Al?O?-CaO-MgO-Na?O-K?O system were examined. The only variable is the ratio of the silicon oxideto alumina at a constant content of other components: MgO, CaO, K?O, Na?O, 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 SiO?/Al?O? ratio on the structure and phase composition of glazes and the nature, and type of formed crystalline phases. PMID:25049171

Partyka, Janusz; Sitarz, Maciej; Le?niak, Magdalena; Gasek, Katarzyna; Jele?, Piotr

2015-01-01

264

Sex ratio dependent dispersal when sex ratios vary between patches.  

PubMed

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 is unaffected by the sex ratio. The analytical models developed to reach these conclusions ignored variance in sex ratios, since this increases the structural complexity of models. For similar reasons finite clutch sizes are also routinely ignored. To overcome these shortfalls, we developed individual based simulations that allowed us to incorporate realistic clutch sizes and binomial variance in sex ratios between patches. We show that under variable sex ratios, males evolve to more readily disperse away from patches with higher sex ratios than lower sex ratios. We show that, while the dispersal rate is insensitive to the sex ratio when sex ratios are precise, it is affected by the number of males with dispersal decreasing as the number of males decreases. PMID:21893071

Nelson, Ronald M; Greeff, Jaco M

2011-12-01

265

The 238U/235U isotope ratio of the Earth and the solar system: Constrains from a gravimetrically calibrated U double spike and implications for absolute Pb-Pb ages  

NASA Astrophysics Data System (ADS)

The ratio of 238U and 235U, the two primordial U isotopes, has been assumed to be constant on Earth and in the solar system. The commonly accepted value for the 238U/235U ratio, which has been used in Pb-Pb dating for the last ~ 30 years, was 137.88. Within the last few years, it has been shown that 1) there are considerable U isotope variations (~1.3‰) within terrestrial material produced by isotope fractionation during chemical reactions [1-3] and 2) there are even larger isotope variations (at least 3.5‰) in calcium-aluminum-rich inclusions (CAIs) in meoteorites that define the currently accepted age of the solar system [4]. These findings are dramatic for geochronology, as a known 238U/235U is a requirement for Pb-Pb dating, the most precise dating technique for absolute ages. As 238U/235U variations can greatly affect the reported absolute Pb-Pb age, understanding and accurately measuring variation of the 238U/235U ratio in various materials is critical, With these new findings, the questions also arises of "How well do we know the average U isotope composition of the Earth and the solar system?" and "How accurate can absolute Pb-Pb ages be?" Our results using a gravimetrically calibrated 233U/236U double spike IRMM 3636 [5] indicate that the U standard NBL 950a, which was commonly used to define the excepted "natural" 238U/235U isotope ratio, has a slightly lower 238U/235U of 137.836 ± 0.024. This value is indistinguishable from the U isotope compositions for NBL 960 and NBL112A, which have been determined by several laboratories, also using the newly calibrated U double spike IRMM 3636 [6]. These findings provide new implications about the average U isotope composition of the Earth and the solar system. Basalts display a very tight range of U isotope variations (~0.25-0.32‰ relative to SRM 950a). Their U isotope composition is also very similar to that of chondrites [4], which however appear to show a slightly larger spread. Accepting terrestrial basalts to be the best representation of the U isotope composition of the Earth and the solar system, and the new 238U/235U for SRM 950a of 137.836, this would result in an average 238U/235U for the Earth and the solar system of ~ 137.80. The effect of a revised 238U/235U ratio on Pb-Pb ages is age dependent. It results in an age overestimation of ~0.8 Ma for the age of the solar system and up to 1.5 Ma for very young material (with bulk Earth U isotope composition). [1] Stirling, C.H., Andersen, M.B., Potter, E.-K., et al. (2007) EPSL 264, 208-225; [2] Weyer, S., Anbar, A. D., Gerdes, A., et al. (2008) GCA 72, 345-359. [3] Bopp, C.H., Lundstrom, C.C., Johnsons, T.M., Glessner, J.G. (2009) Geology 37, 611-614. [4] Brennecka, G.A., Weyer, S., Wadhwa, et al. (2010) Science, 327, p. 449. [5] Richter, S., Alonzo-Munoz, A., Eykens, R., et al. (2008) IJMS 269, 145-148. [6] Richter, S., et al. EGU meeting 2010.

Weyer, Stefan; Noordmann, Janine; Brennecka, Greg; Richter, Stephan

2010-05-01

266

Rumpshaker-like proteolipid protein (PLP) ratio in a mouse model with unperturbed structural and functional integrity of the myelin sheath and axons in the central nervous system.  

PubMed

The gene plp on the X chromosome encodes the isoforms proteolipid protein (PLP) and DM(20), two dominant integral membrane proteins of central nervous system (CNS) myelin. DM(20) results from the activation of the cryptic splice site in exon III of the PLP gene. We inserted a sense-orientated loxP flanked neomycin-gene into intron III of the plp sequence, using homologous recombination in embryonic stem cells and generated the homozygous neoS mouse line. Unlike the previously described complete PLP/DM(20) ablation (plp(-/-)), which has been obtained by introducing a neo-gene in antisense-orientation in the same position of intron III, the plp expression surprisingly revealed reduced mRNA levels. The PLP isoform was reduced to 50%, but DM(20) expression was unaffected. This protein pattern resembles the expression profile of the PLP isoforms in the natural occurring rumpshaker mutant. Electron microscopic examination revealed a normal compaction of CNS-myelin and maintenance of axon integrity. PLP expression levels of the wt control were recovered by Cre excision of the neo-selection gene after intercrossing neoS mice and oligodendrocyte-specific Cre-mice. These data strongly hint at different functions of intron III in PLP/DM(20)-specific splicing and mRNA stability. Furthermore evidence is provided for functionally affected translation products of the PLP gene in the rumpshaker mutant, whereas no PLP-isoform occur in plp(-/-) mice generated by introducing a selectable marker into intron III in antisense orientation. PMID:11424193

Uschkureit, T; Spörkel, O; Büssow, H; Stoffel, W

2001-07-01

267

Woody-grass ratios in a grassy arid system are limited by multi-causal interactions of abiotic constraint, competition and fire.  

PubMed

Predicting changes in vegetation structure in fire-prone arid/semi-arid systems is fraught with uncertainty because the limiting factors to coexistence between grasses and woody plants are unknown. We investigated abiotic and biotic factors influencing boundaries and habitat membership in grassland (Triodia or 'spinifex' grassland)-shrubland (Acacia aneura or 'mulga' shrubland) mosaics in semi-arid central Australia. We used a field experiment to test for the effects of: (1) topographic relief (dune/swale habitat), (2) adult neighbour removal, and (3) soil type (sand/clay) on seedling survival in three shrub and two grass species in reciprocal field plantings. Our results showed that invasion of the shrubland (swale) by neighbouring grassland species is negated by abiotic limitations but competition limits shrubland invasion of the grassland (dune). All species from both habitats had significantly reduced survival in the grassland (dune) in the presence of the dominant grass (Triodia) regardless of soil type or shade. Further, the removal of the dominant grass allowed the shrubland dominant (A. aneura) to establish outside its usual range. Seedling growth and sexual maturation of the shrubland dominant (A. aneura) was slow, implying that repeated fire creates an immaturity risk for this non-sprouter in flammable grassland. By contrast, rapid growth and seed set in the grassland shrubs (facultative sprouters) provides a solution to fire exposure prior to reproductive onset. In terms of landscape dynamics, we argue that grass competition and fire effects are important constraints on shrubland patch expansion, but that their relative importance will vary spatially throughout the landscape because of spatial and temporal rainfall variability. PMID:19859742

Nano, Catherine E M; Clarke, Peter J

2010-03-01

268

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

269

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

270

Helium isotope ratios in Ethiopian Rift basalts  

NASA Astrophysics Data System (ADS)

Helium isotope ratios were measured in olivine and pyroxene phenocrysts from basalts of the Ethiopian Rift Valley and Afar Depression between 6° and 15°N and 37° and 43°E. 3He/ 4He ratios range from 6 to 17 times the atmospheric value (R A = 1.4 × 10 -6), that is, from ratios less than typical MORB (depleted mantle) helium (R/R A= 8 ± 1) to ratios similar to high- 3He hotspots and to the Yellowstone hotspot (R/R A= 16.5). The high 3He/ 4He ratios occur all along the Ethiopian Rift and well up into the Afar Depression, with a maximum value of 17.0 R A at 8°N in the Rift Axis and a high value of 14.2 R A in the central Tat'Ali sector of the Afar Depression. The ratios decrease to MORB-like values near the edge of the Red Sea, and to sub-MORB ratios (5-6 R A) at the northern end of the Rift (Zula Peninsula) and at the southern end, at lakes Abaya and Chamo. The Ethiopian Rift provides the only continental hotspot terrain in which helium isotope ratios can be compared in detail between volcanic lavas and associated geothermal and volcanic gases, a primary motivation for this work. Comparison with our previously measured ratios in fluids and gases (range 2-15 R A) shows excellent agreement in the areas sampled for both lavas and fluids, and indicates that high-temperature volcanic fluids can be used for establishing helium isotope signatures in such terrains. The high- 3He values in both fluids and basalts show that a Primitive Mantle (PM) component is required and that a Lower Mantle High- 3He plume is strongly involved as a driving force in the rifting process of the East African Rift System.

Scarsi, P.; Craig, H.

1996-11-01

271

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

272

Mobile, outdoor continuous-flow isotope-ratio mass spectrometer system for automated high-frequency 13C- and 18O-CO2 analysis for Keeling plot applications.  

PubMed

A continuous-flow isotope-ratio mass spectrometer (CF-IRMS, custom-made GasBenchII and Delta(plus)Advantage, ThermoFinnigan) was installed on a grassland site and interfaced with a closed-path infrared gas analyser (IRGA). The CF-IRMS and IRGA were housed in an air-conditioned travel van. Air was sampled at 1.5 m above the 0.07-m tall grassland canopy, drawn through a 17-m long PTFE tube at a rate of 0.25 L s(-1), and fed to the IRGA and CF-IRMS in series. The IRMS was interfaced with the IRGA via a stainless steel capillary inserted 0.5 m into the sample air outlet tube of the IRGA (forming an open split), a gas-tight pump, and a sample loop attached to the eight-port Valco valve of the continuous-flow interface. Air was pumped through the 0.25-mL sample loop at 10 mL s(-1) (a flushing frequency of 40 Hz). Air samples were analysed at intervals of approx. 2.8 min. Whole system precision was tested in the field using air mixed from pure CO2 and CO2-free air by means of mass flow controllers. The standard deviation of repeated single measurements was 0.21-0.07 per thousand for delta13C and 0.34-0.14 per thousand for delta18O of CO2 in air with mixing ratios ranging between 200-800 micromol mol(-1). The CO2 peak area measured by the IRMS was proportional to the CO2 mixing ratio (r2 = 1.00), allowing estimation of sample air CO2 mixing ratio from IRMS data. A 1-day long measurement cycle of CO2, delta13C and delta18O of air sampled above the grassland canopy was used to test the system for Keeling plot applications. Delta18O exhibited a clear diurnal cycle (4 per thousand range), but short-term (1-h interval) variability was small (average SD 0.38 per thousand). Yet, the correlation between delta18O and CO2 mixing ratio was relatively weak, and this was true for both the whole data set and 1-h subsets. Conversely, the delta13C of all 541 samples measured during the 25.2-h interval fitted well the Keeling regression (r2 = 0.99), yielding an intercept of -27.40 per thousand (+/-0.07 per thousand SE). Useful Keeling regressions (r2 > 0.9, average r2 = 0.96) also resulted from data collected over 1-h intervals of the 12-h long twilight and dark period. These indicated that 13C content of ecosystem respiration was approx. constant near -27.6 per thousand. The precision of the present system is similar to that of current techniques used in ecosystem studies which employ flask sampling and a laboratory-based CF-IRMS. Sampling (and measurement) frequency is greatly increased relative to systems based on flask sampling, and sampling time (0.025 s per sample) is decreased. These features increase the probability for sampling the entire CO2 range which occurs in a given time window. The system obviates sample storage problems, greatly minimises handling needs, and allows extended campaigns of high frequency sampling and analysis with minimal attendance. PMID:15543546

Schnyder, Hans; Schäufele, Rudi; Wenzel, Richard

2004-01-01

273

The sources and evolution of mineralising fluids in iron oxide-copper-gold systems, Norrbotten, Sweden: Constraints from Br/Cl ratios and stable Cl isotopes of fluid inclusion leachates  

NASA Astrophysics Data System (ADS)

We have analysed the halogen concentrations and chlorine stable isotope composition of fluid inclusion leachates from three spatially associated Fe-oxide ± Cu ± Au mineralising systems in Norrbotten, Sweden. Fluid inclusions in late-stage veins in Fe-oxide-apatite deposits contain saline brines and have a wide range of Br/Cl molar ratios, from 0.2 to 1.1 × 10 -3 and ? 37Cl values from -3.1‰ to -1.0‰. Leachates from saline fluid inclusions from the Greenstone and Porphyry hosted Cu-Au prospects have Br/Cl ratios that range from 0.2 to 0.5 × 10 -3 and ? 37Cl values from -5.6‰ to -1.3‰. Finally, the Cu-Au deposits hosted by the Nautanen Deformation Zone (NDZ) have Br/Cl molar ratios from 0.4 to 1.1 × 10 -3 and ? 37Cl values that range from -2.4‰ to +0.5‰, although the bulk of the data fall within 0‰ ± 0.5‰. The Br/Cl ratios of leachates are consistent with the derivation of salinity from magmatic sources or from the dissolution of halite. Most of the isotopic data from the Fe-oxide-apatite and Greenstone deposits are consistent with a mantle derived source of the chlorine, with the exception of the four samples with the most negative values. The origin of the low ? 37Cl values in these samples is unknown but we suggest that there may have been some modification of the Cl-isotope signature due to fractionation between the mineralising fluids and Cl-rich silicate assemblages found in the alteration haloes around the deposits. If such a process has occurred then a modified crustal source of the chlorine for all the samples cannot be ruled out although the amount of fractionation necessary to generate the low ? 37Cl values would be significantly larger. The source of Cl in the NDZ deposits has a crustal signature, which suggests the Cl in this system may be derived from (meta-) evaporites or from input from crustal melts such as granitic pegmatites of the Lina Suite.

Gleeson, S. A.; Smith, M. P.

2009-10-01

274

Odor Concentration Invariance by Chemical Ratio Coding  

PubMed Central

Many animal species rely on chemical signals to extract ecologically important information from the environment. Yet in natural conditions chemical signals will frequently undergo concentration changes that produce differences in both level and pattern of activation of olfactory receptor neurons. Thus, a central problem in olfactory processing is how the system is able to recognize the same stimulus across different concentrations. To signal species identity for mate recognition, some insects use the ratio of two components in a binary chemical mixture to produce a code that is invariant to dilution. Here, using psychophysical methods, we show that rats also classify binary odor mixtures according to the molar ratios of their components, spontaneously generalizing over at least a tenfold concentration range. These results indicate that extracting chemical ratio information is not restricted to pheromone signaling and suggest a general solution for concentration-invariant odor recognition by the mammalian olfactory system. PMID:18958244

Uchida, Naoshige; Mainen, Zachary F.

2007-01-01

275

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

276

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

277

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

278

The Th17/Treg Ratio, IL-1RA and sCD14 Levels in Primary HIV Infection Predict the T-cell Activation Set Point in the Absence of Systemic Microbial Translocation  

PubMed Central

Impairment of the intestinal barrier and subsequent microbial translocation (MT) may be involved in chronic immune activation, which plays a central role in HIV pathogenesis. Th17 cells are critical to prevent MT. The aim of the study was to investigate, in patients with primary HIV infection (PHI), the early relationship between the Th17/Treg ratio, monocyte activation and MT and their impact on the T-cell activation set point, which is known to predict disease progression. 27 patients with early PHI were included in a prospective longitudinal study and followed-up for 6 months. At baseline, the Th17/Treg ratio strongly negatively correlated with the proportion of activated CD8 T cells expressing CD38/HLA-DR or Ki-67. Also, the Th17/Treg ratio was negatively related to viral load and plasma levels of sCD14 and IL-1RA, two markers of monocyte activation. In untreated patients, the Th17/Treg ratio at baseline negatively correlated with CD8 T-cell activation at month 6 defining the T-cell activation set point (% HLA-DR+CD38+ and %Ki-67+). Soluble CD14 and IL-1RA plasma levels also predicted the T-cell activation set point. Levels of I-FABP, a marker of mucosal damages, were similar to healthy controls at baseline but increased at month 6. No decrease in anti-endotoxin core antibody (EndoCAb) and no peptidoglycan were detected during PHI. In addition, 16S rDNA was only detected at low levels in 2 out 27 patients at baseline and in one additional patient at M6. Altogether, data support the hypothesis that T-cell and monocyte activation in PHI are not primarily driven by systemic MT but rather by viral replication. Moreover, the “innate immune set point” defined by the early levels of sCD14 and IL-1RA might be powerful early surrogate markers for disease progression and should be considered for use in clinical practice. PMID:23818854

Chevalier, Mathieu F.; Petitjean, Gael; Dunyach-Remy, Catherine; Didier, Celine; Girard, Pierre-Marie; Manea, Maria Elena; Campa, Pauline; Meyer, Laurence; Rouzioux, Christine; Lavigne, Jean-Philippe; Barre-Sinoussi, Francoise; Scott-Algara, Daniel; Weiss, Laurence

2013-01-01

279

L.-W. Hung and C. T.-C. Nguyen, "Silicide-Based Release of High Aspect Ratio Microstructures," Tech. Digest, 23rd Int. Conf. on Micro Electro Mechanical Systems (MEMS'09), Hong Kong, China, Jan. 24-28, 2010, pp. 120-123.  

E-print Network

L.-W. Hung and C. T.-C. Nguyen, "Silicide-Based Release of High Aspect Ratio Microstructures," Tech. Digest, 23rd IEEE Int. Conf. on Micro Electro Mechanical Systems (MEMS'09), Hong Kong, China, Jan. 24-28, 2010, pp. 120-123. Silicide-Based Release of High Aspect-Ratio Microstructures Li-Wen Hung and Clark T

Nguyen, Clark T.-C.

280

Unpowered to powered failure rate ratio - A key reliability parameter  

NASA Technical Reports Server (NTRS)

It is shown that the initial assumption of the ratio of unpowered to powered failure rates can have a strong influence on the design of a modular system intended for space missions. The analysis is performed for parallel systems and for triple modular redundant systems. Parallel systems are shown to be much more sensitive to the unpowered to powered failure rate ratio than the TMR/Spares systems, however, regardless of which standby redundancy technique is considered, the dependence of the system reliability on this ratio increases as the number of standby spares increases.

Taylor, D. S.

1974-01-01

281

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

282

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

283

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

284

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

285

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

2009-02-11

286

Isotopic ratios in planetary atmospheres.  

PubMed

Recent progress on measurements of isotopic ratios in planetary or satellite atmospheres include measurements of the D/H ratio in the methane of Uranus, Neptune and Titan and in the water of Mars and Venus. Implications of these measurements on our understanding of the formation and evolution of the planets and satellite are discussed. Our current knowledge of the carbon, nitrogen and oxygen isotopic ratios in the atmospheres of these planets, as well as on Jupiter and Saturn, is also reviewed. We finally show what progress can be expected in the very near future due to some new ground-based instrumentation particularly well suited to such studies, and to forthcoming space missions. PMID:11539257

de Bergh, C

1995-03-01

287

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.

2009-01-14

288

Surface Area to Volume Ratio  

NSDL National Science Digital Library

This page contains two documents explaining surface area to volume ratio. The topic is covered at an advanced level in relation to nanotechnology and requires background knowledge in geometry, algebra, and linear and non-linear unit conversions. A powerpoint with illustrations and instructor guide (available as both a Microsoft Word Document and PDF) containing activities are included to aid in teaching this subject.

2012-10-16

289

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

290

An improved prediction of the human in vivo intestinal permeability and BCS class of drugs using the in vitro permeability ratio obtained for rat intestine using an Ussing chamber system.  

PubMed

The Biopharmaceutics Classification System (BCS) was developed to facilitate estimation of the in vivo pharmacokinetic performance of drugs from human intestinal permeability and solubility. However, the measurement of human in vivo intestinal permeability, unlike that of solubility, is problematic and inefficient. Thus, rat in vitro intestinal permeability results obtained via the Ussing chamber technique are often used instead. However, these data could be unreliable due to difficulty in maintaining the viability of the dissected intestinal membrane in the Ussing chamber. Therefore, a more efficient method to obtain a reliable in vitro permeability is mandatory. Here, we propose a new approach by introducing a novel factor called the permeability ratio (PR). Basically, PR is a rat in vitro intestinal permeability obtained from the Ussing chamber, which is then corrected by the permeability of lucifer yellow, a paracellular permeability marker. To prove the validity of the method, 12 model drugs representing different BCS classes were tested, and the correlation with human in vivo intestinal permeability was high. More importantly, the new method perfectly classified all 12 model drugs. The results indicate that PR is a reliable factor with high correlation to human in vivo intestinal permeability, which can further be used to accurately predict the BCS classification. PMID:22934579

Li, Hong; Jin, Hyo-Eon; Shim, Won-Sik; Shim, Chang-Koo

2013-10-01

291

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

292

Global Carbon Reservoir Oxidative Ratios  

NASA Astrophysics Data System (ADS)

Photosynthesis and respiration move carbon and oxygen between the atmosphere and the biosphere at a ratio that is characteristic of the biogeochemical processes involved. This ratio is called the oxidative ratio (OR) of photosynthesis and respiration, and is defined as the ratio of moles of O2 per moles of CO2. This O2/CO2 ratio is a characteristic of biosphere-atmosphere gas fluxes, much like the 13C signature of CO2 transferred between the biosphere and the atmosphere has a characteristic signature. OR values vary on a scale of 0 (CO2) to 2 (CH4), with most ecosystem values clustered between 0.9 and 1.2. Just as 13C can be measured for both carbon fluxes and carbon pools, OR can also be measured for fluxes and pools and can provide information about the processes involved in carbon and oxygen cycling. OR values also provide information about reservoir organic geochemistry because pool OR values are proportional to the oxidation state of carbon (Cox) in the reservoir. OR may prove to be a particularly valuable biogeochemical tracer because of its ability to couple information about ecosystem gas fluxes with ecosystem organic geochemistry. We have developed 3 methods to measure the OR of ecosystem carbon reservoirs and intercalibrated them to assure that they yield accurate, intercomparable data. Using these tools we have built a large enough database of biomass and soil OR values that it is now possible to consider the implications of global patterns in ecosystem OR values. Here we present a map of the natural range in ecosystem OR values and begin to consider its implications. One striking pattern is an apparent offset between soil and biospheric OR values: soil OR values are frequently higher than that of their source biomass. We discuss this trend in the context of soil organic geochemistry and gas fluxes.

Masiello, C. A.; Gallagher, M. E.; Hockaday, W. C.

2010-12-01

293

GUT Scale Fermion Mass Ratios  

NASA Astrophysics Data System (ADS)

We present a series of recent works related to group theoretical factors from GUT symmetry breaking which lead to predictions for the ratios of quark and lepton Yukawa couplings at the unification scale. New predictions for the GUT scale ratios y?/ys, y?/yb and yt/yb in particular are shown and compared to experimental data. For this comparison it is important to include possibly large supersymmetric threshold corrections. Due to this reason the structure of the fermion masses at the GUT scale depends on TeV scale physics and makes GUT scale physics testable at the LHC. We also discuss how this new predictions might lead to predictions for mixing angles by discussing the example of the recently measured last missing leptonic mixing angle ?13 making this new class of GUT models also testable in neutrino experiments.

Spinrath, Martin

2014-10-01

294

Stable Isotope Ratios: Hurricane Olivia  

Microsoft Academic Search

The oxygen and hydrogen isotopic compositions of rains from HurricaneOlivia (1994) in the eastern Pacific were measured. The rains werecollected on 24 and 25 September during airplane flights conducted at anelevation of 3 km. Hurricane Olivia peaked in intensity to a category-4storm between the two dates. Isotope ratios of rains from HurricaneOlivia were markedly lower (d 18O = –13.9‰to –28.8‰)

James R. Lawrence; Stanley David Gedzelman; John Gamache; Michael Black

2002-01-01

295

ELIMINATING THE INITIAL STATE FOR THE GENERALIZED LIKELIHOOD RATIO TEST  

E-print Network

ELIMINATING THE INITIAL STATE FOR THE GENERALIZED LIKELIHOOD RATIO TEST David T¨ornqvist Fredrik of the system using the generalized likelihood ratio test is considered. Careful treatment of the initial state of the model is quite important, in particular for short batch sizes. There are two standard approaches

Gustafsson, Fredrik

296

Turbine rotor blade measurements using infrared pyrometry  

Microsoft Academic Search

An infrared pyrometer system was developed for the noncontacting measurement of metal temperatures on turbine rotor blades. The system with a high bandwidth ratio, a small target size and a high signal-to-noise ratio meets the requirements for the accuracy of temperature measurements to be performed on small gas turbines running at high speeds. The system set-up is described and special

W. Koschel; D. Salden; T. Hoch

1986-01-01

297

Low aspect ratio wing experiment  

NASA Technical Reports Server (NTRS)

This test was initiated to provide validation data on low aspect ratio wings at transonic speeds. The test was conducted so that the data obtained would be useful in the validation of codes, and all boundary condition data required would be measured as part of the test. During the conduct of the test, the measured quantities were checked for repeatability, and when the data would not repeat, the cause was tracked down and either eliminated or included in the measurement uncertainty. The accuracy of the data was in the end limited by wall imperfections of the wind tunnel in which the test was run.

Olsen, Mike; Seegmiller, H. Lee

1994-01-01

298

Statistical moments of the Strehl ratio  

NASA Astrophysics Data System (ADS)

Knowledge of the statistical characteristics of the Strehl ratio is essential for the performance assessment of the existing and future adaptive optics systems. For full assessment not only the mean value of the Strehl ratio but also higher statistical moments are important. Variance is related to the stability of an image and skewness reflects the chance to have in a set of short exposure images more or less images with the quality exceeding the mean. Skewness is a central parameter in the domain of lucky imaging. We present a rigorous theory for the calculation of the mean value, the variance and the skewness of the Strehl ratio. In our approach we represent the residual wavefront as being formed by independent cells. The level of the adaptive optics correction defines the number of the cells and the variance of the cells, which are the two main parameters of our theory. The deliverables are the values of the three moments as the functions of the correction level. We make no further assumptions except for the statistical independence of the cells.

Yaitskova, Natalia; Esselborn, Michael; Gladysz, Szymon

2012-07-01

299

Meteoritic Ce-138/Ce-142 ratio and its evolution  

NASA Astrophysics Data System (ADS)

Cerium isotope ratios were determined for Juvinas, Pasamonte and ALH-78132 eucrites and the Jilin (H4) chondrite. Neodymium isotope ratios and abundances of lanthanum, cerium, neodymium and samarium were also determined for these meteorites. The La-Ce isotopic system, coupled with the Sm-Nd system, provides a new isotope tracer for geo- and cosmo-chemical samples, especially for samples having a Ce anomaly in the rare-earth element patterns.

Shimizu, H.; Tanaka, T.; Masuda, A.

1984-01-01

300

Skylab S-192 ratio codes of soil, mineral, and rock spectra for ratio image selection and interpretation  

NASA Technical Reports Server (NTRS)

A limited theoretical systems study is made of the Skylab S-192 12-channel multispectral scanner's capabilities for geological remote sensing. Laboratory spectra of rocks, minerals, soils, and some vegetation were used to rank the twelve channels and the best twelve of the 66 possible nonreciprocal spectral ratios according to their ability to discriminate among 17 classes of geological targets. Environmental and instrumental noise sources were ignored. The S-192 should be most useful for discriminating minerals deposited by hydrothermal alteration, weathering, and evaporation. Discrimination of igneous rocks will be difficult. Ratio images are recommended over automatic discrimination methods for those geological targets that can be enhanced by ratio imaging. Ratio codes were found for the twelve highest ranked ratios, for use in selecting the ratio images which will best enhance a target of interest. They can also be searched for false alarm candidates for a given target.

Vincent, R. K.; Pillars, W. W.

1974-01-01

301

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

302

Signal to Noise Ratios in Fiber Spectroscopy a component of DocDB 392  

E-print Network

Simpson or Romberg integration. 2.1 Strehl ratio An important concept is the Strehl ratio, which PSF plots for aberrated systems it is customary to divide out the Strehl ratio, thereby normalizingSignal to Noise Ratios in Fiber Spectroscopy a component of DocDB 392 Mike Lampton December 18

California at Berkeley, University of

303

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

304

Variable expansion ratio reaction engine  

SciTech Connect

A variable expansion ratio reaction rocket engine for producing a mainstream of hot combustion gases is described comprising: a reaction chamber including a thrust nozzle portion formed by converging and diverging wall portions in which the diverging portion terminates in a gas discharge and through which the combustion gases pass; a nozzle throat section at the juncture of the convergent-divergent wall portions; rows of circumferentially and axially spaced injection ports formed within the wall portions and communicating therethrough and into the reaction chamber; fluid conduit means in communication with the injection ports; at least one high pressure pump in communication with the fluid conduit means; a fluid containing storage tank including a conduit in communication with the high pressure pump; and means for selectively controlling a flow of fluid out of the tank, through the pump and to the fluid conduit means and the injection ports for controlling a cross-sectional area of the mainstream combustion gases passing through the thrust nozzle.

Wagner, W.R.

1987-11-24

305

Implications of the Nitrogen Isotope Ratio in Titan's Atmosphere for the Nitrogen Ratio in Ammonia in Comets  

NASA Astrophysics Data System (ADS)

The D/H ratio of water measured in solar system bodies has been established as a tool for determining the conditions under which bodies such as comets or icy moons formed. This ratio varies significantly and indicates complex thermal and chemical evolution of the solar nebula during solar system and planetary formation. Nitrogen isotope ratios also vary significantly, and in some but not all cases correlate to D/H ratios, but are poorly understood. Nitrogen in the solar nebula was primarily in the form of atomic and molecular nitrogen. The isotope ratio (14N/15N) of this reservoir is expected to be ~435 based on the ratio measured in Jupiter's atmosphere, because the atmosphere of Jupiter is made up of gas captured from the solar nebula (Owen et al., 2001). The terrestrial atmospheric ratio is 272, which is close to the ratio measured in the Earth's mantle. This may be the primordial ratio for nitrogen delivered to Earth depending on the amount of exchange between the atmosphere and the mantle and any atmospheric fractionation processes that may have influenced the ratio over time. Comets are a possible source of nitrogen in the Earth's atmosphere (Hutsmekers et al., 2009), although chondrites have also been suggested as a source (Marty, 2012). In the case of comets, nitrogen would have been essentially retained in the form of ammonia (Mousis et al., 2012), which is the most abundant form of nitrogen in comets. The nitrogen in Titan's atmosphere is expected to have originated as ammonia hydrates and converted to N2 early in Titan's history (Atreya et al., 1978). The nitrogen ratio in Titan's atmosphere is ~170, which is significantly enriched in the heavy isotope compared to the terrestrial value. We will discuss the evolution of the nitrogen ratio in Titan's atmosphere (Mandt et al., 2009), the limits of the primordial ratio in ammonia, and the implications for this ratio for the isotope ratio in ammonia in comets that should be measured by the ROSINA instrument on Rosetta in comet 67P/Churyumov-Gerasimenko (Balsiger et al., 2007). Atreya, S., et al., 1978, Science, 201, 611-613. Balsiger, H., et al., 2007, Space Science Reviews, 128, 745-801. Hutsmekers et al., 2009, Icarus, 204, 346-348. Marty, B., 2012, Earth and Planetary Science Letters, 313-314, 56-66. Mandt, K. E., et al., 2009, Planetary and Space Science, 57, 1917-1930. Mousis, O., et al., 2012, The Astrophysical Journal, 757, 146. Owen, T. et al., 2001, The Astrophysical Journal, 553, L77-L79.

Mandt, K.; Mousis, O.

2013-12-01

306

Systematic study of the ?-/?+ ratio in heavy-ion collisions with the same neutron/proton ratio but different masses  

NASA Astrophysics Data System (ADS)

A systematic study of the ?-/?+ ratio in heavy-ion collisions with the same neutron/proton ratio but different masses can help single out effects of the nuclear mean field on pion production. Based on simulations using the IBUU04 transport model, it is found that the ?-/?+ ratio in head-on collisions of Ca48+Ca48, Sn124+Sn124, and Au197+Au197 at beam energies from 0.25 to 0.6 GeV/nucleon increases with increasing the system size or decreasing the beam energies. A comprehensive analysis of the dynamical isospin fractionation and the ?-/?+ ratio as well as their time evolution and spatial distributions demonstrates clearly that the ?-/?+ ratio is an effective probe of the high-density behavior of the nuclear symmetry energy.

Zhang, Ming; Xiao, Zhi-Gang; Li, Bao-An; Chen, Lie-Wen; Yong, Gao-Chan; Zhu, Sheng-Jiang

2009-09-01

307

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

308

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

309

Compression-ratio-based seizure detection.  

PubMed

For wireless seizure monitoring devices seizure detection and data compression are two critical tasks that need to be carefully designed against a very tight power budget to maximize the battery life. These two tasks are usually considered separately and algorithms for each are developed separately. In this paper, we consider having a single low-power algorithm for implementing both seizure detection and data compression. Towards that end, we investigated compression ratio (CR) as a seizure marker and show that the seizure detection can be achieved as a by-product of compression with no additional cost, and thus overall system power can be reduced. We show that the proposed method, the CR-based seizure detection has promising performance with 88% seizure detection accuracy, and 5.5 false positives per hour (FPh) without any computation overhead. PMID:24109861

Sha, Chung-Lin; Kim, Taehoon; Artan, N Sertac; Chao, H Jonathan

2013-01-01

310

Density Ratio Examples Semiparametric Statistical Formulation  

E-print Network

UMinformal Density Ratio Examples Semiparametric Statistical Formulation Combined semiparametric density estimators Semiparametric regression Application to Testicular Germ Cell Cancer Semiparametric Density Ratio Examples Semiparametric Statistical Formulation Combined semiparametric density estimators

Johnson, Raymond L.

311

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.

Weinberg, Sheryl

1999-01-16

312

Combined measurements of a UV mini MAX-DOAS system and a TX for retrieval of ambient trace gas mixing ratio: Comparisons with combined RTM and MAX-DOAS methods  

NASA Astrophysics Data System (ADS)

A measurement method combining multi-axis differential optical absorption spectroscopy (MAX-DOAS) and a transmissometer (TX) is introduced as a means of retrieving surface trace gas mixing ratios in ambient air. The combined measurement method was utilized to derive surface NO 2 mixing ratios from 27 March to 11 May 2007 in Seoul, Korea. To convert the differential slant column density (DSCD) to the volume mixing ratio (VMR), the light path length (LPL) along the MAX-DOAS line of sight was derived using the light extinction coefficient and Ångstrom exponent data obtained by a TX and sunphotometer, respectively. Temporal variations of the NO 2 VMRs at the 0-1 km layer obtained from radiative transfer model (RTM) simulations coupled with MAX-DOAS data show similar patterns, but with reduced magnitudes, to the ground level data and those of the combined MAX-DOAS and TX measurements at 0.08 km. The NO 2 VMRs retrieved by the combined measurement were in agreement with those obtained from the RTM simulations coupled with MAX-DOAS data and the in-situ measurements within 40 and 50%, respectively. The coefficient of determination ( R2) of 0.75 was obtained between the combined measurement data sets and those of the RTM simulations coupled with MAX-DOAS data whereas that between the combined measurement data sets and those of the in-situ measurements was 0.53. The coefficient of determination ( R2) between the data sets derived from the RTM simulations coupled with MAX-DOAS data and those of the in-situ measurements was 0.67 with the scatter of the correlation within the 50% range.

Lee, Hanlim; Ryu, Jaeyong; Kim, Jhoon; Noh, Youngmin; Yoon, Younghun

2011-12-01

313

12 CFR 567.8 - Leverage ratio.  

Code of Federal Regulations, 2010 CFR

...Requirements § 567.8 Leverage ratio. (a) The minimum leverage...chapter, shall consist of a ratio of core capital to adjusted...excellent asset quality, high liquidity, and good earnings. ...requirement shall consist of a ratio of core capital to...

2010-01-01

314

Signal-to-noise-ratio expressions in optical diffusion tomography  

NASA Astrophysics Data System (ADS)

Optical diffusion tomography is a technology that is employed to obtain images of the heterogeneous nature of turbid media by using optical radiation. Noise ultimately limits the achievable spatial resolution in these reconstructed images; therefore it is of interest to develop signal-to-noise-ratio expressions that relate spatial resolution in the images to the underlying system and material properties. In this study, Fourier-domain signal-to-noise-ratio expressions are derived for two types of optical diffusion tomography systems: those that use amplitude-modulated illumination sources and those that use continuous-wave illumination sources. The signal-to-noise-ratio expressions are compared for these two types of systems and are validated by laboratory data.

Matson, Charles L.

2002-05-01

315

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

316

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

317

Turbine rotor blade measurements using infrared pyrometry  

NASA Astrophysics Data System (ADS)

An infrared pyrometer system was developed for the noncontacting measurement of metal temperatures on turbine rotor blades. The system with a high bandwidth ratio, a small target size and a high signal-to-noise ratio meets the requirements for the accuracy of temperature measurements to be performed on small gas turbines running at high speeds. The system set-up is described and special features of the probe head design, the lay-out of the detector/amplifier unit and the signal processing are discussed in detail. Results of the automated calibration of an infrared pyrometer system concerning the influence of variations in the target-to-lens distance, in the lens stop diameter and in the observation angle on the detector signal output are reported. Finally some results of temperature measurements obtained for the cooled rotor blades of a small research turbine are presented.

Koschel, W.; Salden, D.; Hoch, T.

1986-11-01

318

Quantifying Void Ratio in Granular Materials Using Voronoi Tessellation  

NASA Technical Reports Server (NTRS)

Voronoi technique was used to calculate the local void ratio distribution of granular materials. It was implemented in an application-oriented image processing and analysis algorithm capable of extracting object edges, separating adjacent particles, obtaining the centroid of each particle, generating Voronoi polygons, and calculating the local void ratio. Details of the algorithm capabilities and features are presented. Verification calculations included performing manual digitization of synthetic images using Oda's method and Voronoi polygon system. The developed algorithm yielded very accurate measurements of the local void ratio distribution. Voronoi tessellation has the advantage, compared to Oda's method, of offering a well-defined polygon generation criterion that can be implemented in an algorithm to automatically calculate local void ratio of particulate materials.

Alshibli, Khalid A.; El-Saidany, Hany A.; Rose, M. Franklin (Technical Monitor)

2000-01-01

319

The effect of sex ratios on suicide.  

PubMed

Whereas sex ratios are likely to affect the likelihood of marriage, how sex ratios affect health and survival is underexplored. This study uses suicide as a measure of mental health and examines how suicides are affected by sex ratios. As women tend to marry men older than themselves, shrinking populations will lead to higher sex ratios (i.e., higher proportions of men) in the marriage market. Using data from Japan, I find that high sex ratios, both early-life and current, are correlated with higher male suicide rates, whereas female suicide rates are generally not affected. The results of this study have important implications for public health in countries where imbalanced sex ratios are a concern. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23943552

Kuroki, Masanori

2014-12-01

320

Varying penetration ratios of wind turbine technologies for voltage and frequency stability  

Microsoft Academic Search

This paper examines the ability of a power system to accommodate wind generation with varying ratios of doubly-fed induction generator and fixed speed induction generator turbines from both static and dynamic aspects. By controlling the ratio between the two types of turbines, voltage stability is maintained for steady-state conditions for a large range of varying wind speeds. Using the ratio

Eknath Vittal; Andrew Keane; Mark O'Malley

2008-01-01

321

Calibration of a deformable mirror and Strehl ratio measurements by use of phase diversity  

E-print Network

Calibration of a deformable mirror and Strehl ratio measurements by use of phase diversity Mats G-front errors in the optical setup, including the mirror, and measuring Strehl ratios and residual higher-order aberrations. The Strehl ratio of the calibrated system is measured to be 0.975, corresponding to 1 40 wave rms

Löfdahl, Mats

322

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

323

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

324

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

325

HeterophiltoLymphocyteRatio CANT CBTHABTO NOMO HOSP  

E-print Network

* * * (Right) Differences in H:L ratio for 5 bird species across an urban-rural gradient and (below) between those with and without blood parasites. * sig. at P System Passeridae HOSPUS Pipilio CANT:L was used as an indicator of the innate immune response. Urban CBTHs had more heterophils (t=4.78, P=0

Hall, Sharon J.

326

Generalized Likelihood Ratio Test for Voltage Dip Detection  

Microsoft Academic Search

An alternative detection algorithm, based on the gen- eralized likelihood ratio test (GLRT), is proposed for the detection of voltage dips in power systems. The proposed method is com- pared to the classical approaches based on the voltage root mean square. It is shown that the GLRT may provide competitive perfor- mance in terms of capability of correctly detecting the

Antonio Moschitta; Paolo Carbone; Carlo Muscas

2011-01-01

327

Measurement of D-Meson Branching Ratios.  

National Technical Information Service (NTIS)

Charm data from 360 GeV/c (pi-)p interactions are used to give results on D-meson branching ratios. The analysis is based on 114 charm events containing 183 observed charm particle decays. The authors present topological branching ratios and decay multipl...

M. Aguilar-Benitez, W. W. M. Allison, J. F. Baland, W. Bartl, V. M. Begalli

1985-01-01

328

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

329

Losing money with a high Sharpe ratio  

Microsoft Academic Search

A simple example shows that losing all money is compatible with a very high Sharpe ratio (as computed after losing all money). However, the only way that the Sharpe ratio can be high while losing money is that there is a period in which all or almost all money is lost. This note explores the best achievable Sharpe and Sortino

Vladimir Vovk

2011-01-01

330

Ratio Rule Mining from Multiple Data Sources  

Microsoft Academic Search

Both multiple source data mining and streaming data mining problems have attracted much attention in the past decade. In contrast to traditional association-rule mining, to capture the quantitative association knowledge, a new paradigm called Ratio Rule (RR) was proposed recently. We extend this framework to mining ratio rules from multiple source data streams which is a novel and challenging problem.

Jun Yan; Qiang Yang; Benyu Zhang; Qiansheng Cheng; Zheng Chen

331

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

332

The Divine Ratio and Golden Rectangles.  

ERIC Educational Resources Information Center

The material examines aspects of Fibonacci and Lucas sequences, the generation of the Divine Ratio, and the nature of this ratio in golden rectangles, triangles, and figures made up of golden triangles. It is noted Lucas sequence is formed like Fibonacci but has one and three as the first elements. (Author/MP)

Cooper, Martin

1982-01-01

333

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.

Institute, Economic P.

334

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

335

Duty ratio of cooperative molecular motors  

NASA Astrophysics Data System (ADS)

Molecular motors are found throughout the cells of the human body and have many different and important roles. These micromachines move along filament tracks and have the ability to convert chemical energy into mechanical work that powers cellular motility. Different types of motors are characterized by different duty ratios, which is the fraction of time that a motor is attached to its filament. In the case of myosin II (a nonprocessive molecular machine with a low duty ratio), cooperativity between several motors is essential to induce motion along its actin filament track. In this work we use statistical mechanical tools to calculate the duty ratio of cooperative molecular motors. The model suggests that the effective duty ratio of nonprocessive motors that work in cooperation is lower than the duty ratio of the individual motors. The origin of this effect is the elastic tension that develops in the filament which is relieved when motors detach from the track.

Dharan, Nadiv; Farago, Oded

2012-02-01

336

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

337

Electrocardiogram (ECG) Biometric Authentication Using Pulse Active Ratio (PAR)  

Microsoft Academic Search

Biometric authentication is a one-to-one verification process.A successful biometric system must be capable of avoiding a fraudulent claim while at the same time ensuring the privacy of individuals. This paper presents a novel framework for using the electrocardiogram (ECG) as a biometric system for human au- thentication. A new feature extraction technique known as pulse active ratio (PAR) is derived

Sairul I. Safie; John J. Soraghan; Lykourgos Petropoulakis

2011-01-01

338

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

339

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

340

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

341

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

342

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

343

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

344

Noncontact thermal pyrometry for condensed materials  

NASA Astrophysics Data System (ADS)

Pyrometry technique is suggested aimed at minimizing the measurement error and increasing the accuracy of contactless temperature measurements. Significantly, the suggested method of pyrometer calibration allows using a two-tiered approach with preliminary or additional recording of the system's state and thermal radiation to refine temperature measurements. To improve the reliability of results and extend the application range of thermal pyrometry, it is necessary to decrease the influence of the relative error of the spectral ratio on measuring data.

Dubas, L. G.

2013-01-01

345

Reduction ratio control for continuously variable transmission  

SciTech Connect

This patent describes a reduction ratio control for a continuously variable transmission of a motor vehicle, the continuously variable transmission being connected to an engine of the motor vehicle to be driven thereby, the reduction ratio control comprising: means for carrying out a reduction ratio change of the continuously variable transmission in such a manner as to decrease a difference between an actual value in a predetermined operating variable and a target value in the predetermined operating variable toward zero; means for determining a deceleration which the motor vehicle is subject to; means for changing the target value to a new target value in response to the deceleration after the deceleration which the motor vehicle is subjected to is determined; and the means for carrying out the reduction ratio change causes the actual value to approach the new target value quicker than it controlled the actual value to approach the target value.

Kumura, H.

1989-06-06

346

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

347

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

348

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

349

Meteorological Effects on Air/Fuel Ratio  

E-print Network

METEOROLOGICAL EFFECTS ON AIR/FUEL RATIO John L. Ferri GTE Products Corporation Towanda, Pennsylvania ABSTRACT Air is a convenient and inexpensive source of oxygen for most combustion processes. However, the oxygen content of the air...METEOROLOGICAL EFFECTS ON AIR/FUEL RATIO John L. Ferri GTE Products Corporation Towanda, Pennsylvania ABSTRACT Air is a convenient and inexpensive source of oxygen for most combustion processes. However, the oxygen content of the air...

Ferri, J. L.

1984-01-01

350

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

351

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

352

Circular-polarization ratios for aggregates of spherical particles  

NASA Astrophysics Data System (ADS)

A basic strategy for observing a small solar-system object using radar is to measure the distribution of echo power in time delay and Doppler frequency for a circularly polarized transmitted wave, in the same and opposite senses of circular polarization. The measurement can be repeated for differing orientations and plane-of-sky directions of the object. The circular-polarization ratio ? is the ratio of the echo power in the same circular-polarization state (SC) to that in the opposite circular-polarization state (OC). The ratio ? is often the most important physical observable with the radar technique, as it provides the best indications for wavelength-scale complexity of the surface. At the typical transmitter frequencies of 2380 MHz or 8495 MHz, the wavelengths are 12.6 cm or 3.5 cm, respectively. We model electromagnetic scattering from closely-packed random aggregates of spheres imitating the structure of an asteroid's regolith. Both scattering and absorption of the electromagnetic wave are treated. The Multiple-Sphere T -Matrix Method computer software (MSTM; D. W. Mackowski and M. I. Mishchenko, JQSRT 112, 1282, 2011) is utilized to study how different parameters affect the circular-polarization ratio, e.g., the size distribution and electric permittivities of the spherical particles forming the different aggregates. Our primary goal is to see if the computed circular-polarization ratios can be linked to the observational data of asteroids detected with radar. The results of the simulations show striking structure for the circular-polarization ratio as a function of the size parameter and the electric permittivity of the medium. Also differences between aggregates of monodisperse and polydisperse spheres clearly exist: the aggregates consisting of polydisperse spherical particles, and hence, showing more complex structure and surface, result in circular-polarization ratios higher than the aggregates of monodisperse spherical particles, probably due to the increased significance of multiple scattering. Most importantly, the simulations show how the variations of the different parameters affect the ratio, indicating reasons for the variations in the observed data. We have simulated circular-polarization ratios for aggregates of monodisperse particles, and are currently initiating simulations for aggregates of polydisperse spheres.

Virkki, A.; Muinonen, K.; Penttilä, A.

2012-04-01

353

Interspecies comparisons of A/D ratios: A/D ratios are not constant across species.  

PubMed

The hypothesis that the ratio of the adult (A) and developmental (D) toxicity of a chemical is constant across animal species has been proposed as the basis for identifying developmental hazards, both from traditional developmental toxicity screens using laboratory mammals and from alternative systems such as the coelenterate Hydra attenuata. The purpose of this study was to determine whether A/D ratios are constant across species. The developmental and adult toxicity of 14 chemicals was assessed in four phylogenetically different species. The chemicals tested were aminopterin, bromodeoxyuridine, cadmium chloride, caffeine, congo red, dinocap, dinoseb, diphenylhydantoin, epinephrine, ethylenethiourea, 2-methoxyethanol, mirex, all-trans-retinoic acid, and trypan blue. These chemicals are representative of a variety of toxic mechanisms and a range of potencies. Species used were the CD-1 mouse (Mus musculus), South African clawed frog (Xenopus laevis), fathead minnow (Pimephales promelas), and fruit fly (Drosophila melanogaster). The mouse is a commonly used model for developmental toxicity. The other species are known to be sensitive to mammalian toxicants and have well-studied embryologies. Mice were exposed to chemicals either po or by sc injection using a standard Segment II protocol in which pregnant mice are administered the test agent on a daily basis from Gestation Days 6 to 15, adult toxicity is evaluated during and after treatment, and developmental toxicity is evaluated in fetuses at term. The exposure duration spans the period of organ formation in the embryo. The other species were exposed to test agents for a developmentally comparable period. This was from blastulation (shortly after fertilization) to the free-swimming tadpole stage in Xenopus (4 days); from blastulation to the free-swimming fry stage in Pimephales (7 days); and for the entire larval period, the period of development of the imaginal discs, in Drosophila (6 days). Adults of each species were exposed to test agents for 4, 7, and 6 days, respectively. The route of exposure was via the water column in the two aquatic species and via the diet in Drosophila. Statistical lowest observed effect level (LOEL) and no observed effect level (NOEL) values were generated for adult and developmental toxicity in each species. A/D ratios were calculated using both LOEL and NOEL values.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1843185

Daston, G P; Rogers, J M; Versteeg, D J; Sabourin, T D; Baines, D; Marsh, S S

1991-11-01

354

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

355

Examining Earthquake Scaling Via Event Ratio Levels  

NASA Astrophysics Data System (ADS)

A challenge with using corner frequency to interpret stress parameter scaling is that stress drop and apparent stress are related to the cube of the corner frequency. In practice this leads to high levels of uncertainty in measured stress from since the uncertainty in measuring the corner frequency is cubed to determine uncertainty in the stress parameters. We develop a new approach using the low and high frequency levels of spectral ratios between two closely located events recorded at the same stations. This approach has a number of advantages over more traditional corner frequency fitting, either in spectral ratios or individual spectra. First, if the bandwidth of the spectral ratio is sufficient, the levels can be measured at many individual frequency points and averaged, reducing the measurement error. Second the apparent stress (and stress drop) are related to the high frequency level to the 3/2 power so the measurement uncertainty is not as amplified as when using the corner frequency. Finally, if the bandwidth is sufficiently broad to determine both the spectral ratio low and high frequency levels, the apparent stress (or stress drop) ratio can be determined without the need to use any other measurements (e.g., moment, fault area), which of course have their own measurement uncertainties. We will show a number examples taken from a wide variety of crustal earthquake sequences. Example of the sigmoid formed by a spectral ratio between two hypothetical events for two different cases of stress scaling using the models described in this paper. Event 1 is Mw 6.0 event and event 2 is an Mw 4.0 event. In the self-similar case both have an apparent stress of 3 MPa, in the non-self-similar case the large event apparent stress is 3 MPA and the smaller one is 1 MPa. Note that ratio reaches different constant levels. The low frequency level (LVL) is the ratio of the moments and high frequency level (HFL) depends on the stress parameters. In this paper we derive the relationships shown for the LVL and HFL values, and how these can be used to determine the apparent stress ratio between two events.

Walter, W. R.; Yoo, S.; Mayeda, K. M.; Gok, R.

2013-12-01

356

Pollen Histochemistry and Pollen : Ovule Ratios in Zingiberaceae  

PubMed Central

• Background and Aims Pollen grains of 37 species from 11 genera in the family Zingiberaceae were examined to assess qualitatively starch or lipid contents; the pollen grain and ovule numbers per flower and pollen : ovule ratios were also counted and calculated. Pollen : ovule ratios were studied to reveal patterns of variation in the Zingiberaceae. • Methods Freshly open flowers with dehiscing anthers were collected at random from plants growing in natural habitats or in botanical gardens. Presence of lipids or starch in pollen grains was tested by Sudan solution and IKI solution, respectively, and examined under a microscope. To estimate the pollen and ovule numbers per flower, one anther from each bud was carefully dissected and all pollen grains were counted; ovaries were carefully dissected out of each flower and counted. Whenever possible, at least 10–15 buds were used in the determination. • Key Results Thirty-three of all the 37 species examined had starchy pollen. Starch was not found in only four species and lipid was not found in only one species; among the four tribes in subfamily Zingiberoideae, all species of Zingibereae and Globbeae had pollen with no starch, Alpineae and Hedychieae had pollen with and without starch, whereas, all species of subfamily Costoideae had starchy pollen with abundant lipids. The mean pollen : ovule ratios in the members of the Zingiberaceae investigated range from 3·25 ± 1·56 to 616·52 ± 117·83. • Conclusions The pollen nutrition types seemed not related to mating systems. The pollen : ovule ratios in members of the Zingiberaceae with the same breeding system are noticeably lower than those recorded by previous authors. The lower pollen : ovule ratios in this family are presumed to be related to the highly efficient pollination systems, mediated by pollen which can be quite glutinous and the relatively large stigma area. In most of the Alpinia species the anaflexistylous flowers have much larger numbers of pollen grains and higher pollen : ovule ratios than the cataflexistylous flowers. There are significant differences in mean pollen grain numbers and pollen : ovule ratios between different life forms but ovule numbers are approximately the same. PMID:15306561

WANG, YING-QIANG; ZHANG, DIAN-XIANG; CHEN, ZHONG-YI

2004-01-01

357

Development of a Micropyrolyzer for Enhanced Isotope Ratio Measurement  

SciTech Connect

This paper presents design, fabrication and testing of a micro scale reactor for the pyrolysis of organic compounds. The reactor system described here is suitable for use in enhanced isotope ratio measurement in a continuous flow mode. A characteristic of such a system is it can be utilized to pyrolyze organic compounds with sample size 20-50 times smaller than conventional. Results have shown that organic compounds, such as 1-butanol, ethanol, and ethanol amine, can be fully decomposed to desired products CO and H2, at temperature of 1200oC, which is 200oC lower than conventionally reported. Undesired products methane and CO2 are eliminated in the pyrolysis process. The proof-of-concept experimental results clearly demonstrate that the micro pyrolyzer can be readily integrated with isotope ratio mass spectrometer (IRMS) to differentiate between different sources of the same materials.

Hu, Jianli; Dagle, Robert A.; Johnson, Bradley R.; Kreuzer, Helen W.; Gaspar, Daniel J.; Roberts, Benjamin Q.; Alexander, M. L.

2008-11-19

358

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

359

BrO/SO2 ratios from the NOVAC network  

NASA Astrophysics Data System (ADS)

The halogen/sulphur ratio is an important indicator for dynamical changes in the upper part of a volcanic system. In particular, the BrO/SO2 ratio was recently suggested to be an indicator for changes in volcanic activity. This ratio can be assessed by Differential Optical Absorption Spectroscopy measurements in the UV. SO2 is emitted by volcanoes and relatively stable on time-scales usually observed during ground-based remote-sensing measurements. On the other hand, BrO is not directly released from volcanoes, but probably a product of photochemical oxidation of primary emitted HBr in the atmosphere. This study presents BrO/SO2 ratios measured from the Network for Observation of Volcanic and Atmospheric Change (NOVAC). NOVAC has so far installed 64 spectrometers at 24 volcanoes world-wide, some of which measure volcanic gas and their fluxes for 7 years. This vast database will allow to correlate changes in the BrO/SO2 ratio with volcanic activity and to investigate other parameters that might influence the formation of BrO in the volcanic plume, i.e., meteorology and time since release from the volcano. We show that it is possible to obtain BrO/SO2 ratios from the Type 1 NOVAC instrumentation at Nevado del Ruiz, Colombia, and present an adapted data evaluation scheme. Issues in the evaluation of automatically acquired spectroscopic data will be discussed and possible solutions will be suggested and application to the data will be shown. This includes the correct parameter settings for the BrO and SO2 evaluation, the availability of reference spectra and problems with the variation of the instrument temperature. Measurement results and BrO/SO2 time-series will be presented and the possibilities of the data set will be illustrated.

Lübcke, Peter; Bobrowski, Nicole; Galle, Bo; Garzon, Guastavo; Vogel, Leif; Platt, Ulrich

2013-04-01

360

Poisson's ratio of high-performance concrete  

SciTech Connect

This article outlines an experimental and numerical study on Poisson's ratio of high-performance concrete subjected to air or sealed curing. Eight qualities of concrete (about 100 cylinders and 900 cubes) were studied, both young and in the mature state. The concretes contained between 5 and 10% silica fume, and two concretes in addition contained air-entrainment. Parallel studies of strength and internal relative humidity were carried out. The results indicate that Poisson's ratio of high-performance concrete is slightly smaller than that of normal-strength concrete. Analyses of the influence of maturity, type of aggregate, and moisture on Poisson's ratio are also presented. The project was carried out from 1991 to 1998.

Persson, B.

1999-10-01

361

He/Ar ratio: Earthquake harbinger  

NASA Astrophysics Data System (ADS)

Helium and argon, squeezed out of the earth through fissures by deep internal pressures, may signal an imminent earthquake. There has been little evidence, however, directly linking stress with gas emissions. Ryuichi Sugisaki of the earth sciences department at Nagoya University in Japan reports in the June 12 Science that the variations of the He/Ar ratio of gas bubbles in a mineral spring coincide with underground stresses caused by the earth tide.‘A comparison of the variation of strain in the ground resulting from the earth tide with the observed fluctuation of the ratio shows a good correlation,’ Sugisaki wrote. In addition, he says that the ratio fluctuation is more closely tied to the tidal strain than to atmospheric pressure or temperature.

Richman, Barbara T.

362

Child Underreporting, Fertility, and Sex Ratio Imbalance in China  

Microsoft Academic Search

Child underreporting is often neglected in studies of fertility and sex ratio imbalance in China. To improve estimates of\\u000a these measures, I use intercensal comparisons to identify a rise in underreporting, which followed the increased enforcement\\u000a and penalization under the birth planning system in 1991. A new triangulation of evidence indicates that about 19% of children\\u000a at ages 0–4 were

Daniel Goodkind

2011-01-01

363

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

364

Algorithms for high aspect ratio oriented triangulations  

NASA Technical Reports Server (NTRS)

Grid generation plays an integral part in the solution of computational fluid dynamics problems for aerodynamics applications. A major difficulty with standard structured grid generation, which produces quadrilateral (or hexahedral) elements with implicit connectivity, has been the requirement for a great deal of human intervention in developing grids around complex configurations. This has led to investigations into unstructured grids with explicit connectivities, which are primarily composed of triangular (or tetrahedral) elements, although other subdivisions of convex cells may be used. The existence of large gradients in the solution of aerodynamic problems may be exploited to reduce the computational effort by using high aspect ratio elements in high gradient regions. However, the heuristic approaches currently in use do not adequately address this need for high aspect ratio unstructured grids. High aspect ratio triangulations very often produce the large angles that are to be avoided. Point generation techniques based on contour or front generation are judged to be the most promising in terms of being able to handle complicated multiple body objects, with this technique lending itself well to adaptivity. The eventual goal encompasses several phases: first, a partitioning phase, in which the Voronoi diagram of a set of points and line segments (the input set) will be generated to partition the input domain; second, a contour generation phase in which body-conforming contours are used to subdivide the partition further as well as introduce the foundation for aspect ratio control, and; third, a Steiner triangulation phase in which points are added to the partition to enable triangulation while controlling angle bounds and aspect ratio. This provides a combination of the advancing front/contour techniques and refinement. By using a front, aspect ratio can be better controlled. By using refinement, bounds on angles can be maintained, while attempting to minimize the number of Steiner points.

Posenau, Mary-Anne K.

1995-01-01

365

Enantiomer Ratios of Meteoritic Sugar Derivatives  

NASA Technical Reports Server (NTRS)

Carbonaceous meteorites contain a diverse suite of soluble organic compounds. Studies of these compounds reveal the Solar System's earliest organic chemistry. Among the classes of organic compounds found in meteorites are keto acids (pyruvic acid, etc.), hydroxy tricarboxylic acids (1), amino acids, amides, purines and pyrimidines. The Murchison and Murray meteorites are the most studied for soluble and insoluble organic compounds and organic carbon phases. The majority of (indigenous) meteoritic compounds are racemic, (i.e., their D/L enantiomer ratios are 50:50). However, some of the more unusual (non-protein) amino acids contain slightly more of one enantiomer (usually the L) than the other. This presentation focuses on the enantiomer analyses of three to six-carbon (3C to 6C) meteoritic sugar acids. The molecular and enantiomer analysis of corresponding sugar alcohols will also be discussed. Detailed analytical procedures for sugar-acid enantiomers have been described. Results of several meteorite analyses show that glyceric acid is consistently racemic (or nearly so) as expected of non-biological mechanisms of synthesis. Also racemic are 4-C deoxy sugar acids: 2-methyl glyceric acid; 2,4-dihydroxybutyric acid; 2,3-dihydroxybutyric acid (two diastereomers); and 3,4-dihydroxybutyric acid. However, a 4C acid, threonic acid, has never been observed as racemic, i.e., it possesses a large D excess. In several samples of Murchison and one of GRA 95229 (possibly the most pristine carbonaceous meteorite yet analyzed) threonic acid has nearly the same D enrichment. In Murchison, preliminary isotopic measurements of individual threonic acid enantiomers point towards extraterrestrial sources of the D enrichment. Enantiomer analyses of the 5C mono-sugar acids, ribonic, arabinonic, xylonic, and lyxonic also show large D excesses. It is worth noting that all four of these acids (all of the possible straight-chained 5C sugar acids) are present in meteorites, including the rare lyxonic acid, and their relative abundances are in equilibrium proportions. In addition (in contrast to the above D-only excesses), some of the above acids are found in biology as the L enantiomer. Whether rare are common, all of the 6C sugar acids that are present in sufficient amounts to allow enantiomer analysis (Mannonic, gluconic, altronic, talonic, idonic, gulonic, and galactonic) also, apparently, possess significant D excesses.

Cooper, George

2012-01-01

366

Mechanisms of ratio fluorescence imaging of diseased tissue  

NASA Astrophysics Data System (ADS)

The in vivo laser induced fluorescence experiments have shown that the intrinsic LIF spectral shape of bronchial dysplasia and carcinoma in situ does not differ significantly from that of normal bronchial tissue. However, the intensity of LIF from diseased tissue is significantly reduced. Comparing the in vivo measurement results and the Monte Carlo modeling based on measured optical properties, we have hypothesized that the factors which cause the fluorescence reduction in diseased tissue may be (i) thicker abnormal epithelium, (ii) slightly higher blood content, and (iii) reduction in the density of the fluorescence source density of submucosa. Based on the above hypothesis, the Monte Carlo simulation code was modified to allow one to model spectrally distorted (when compared to the intrinsic fluorescence spectra) fluorescence collected by an imaging system. The fluorescence images excited by He-Cd laser (442 nm) at three typical wavelengths (500 nm, 577 nm and 630 nm) were analyzed by using Monte Carlo simulations. The results indicated that even if there is not significant difference in spectral shape of intrinsic fluorescence between normal and abnormal bronchial tissue, the ratio of red (630 nm) to green (500 nm) fluorescence image from the modeled normal site is significantly higher than that from modeled abnormal site. And abnormal tissue can be identified by the ratio imaging technique. The major factor causing the increased red/green ratio at abnormal tissue sites is the different tissue optics between normal and abnormal tissue. In the in vivo study, five bronchial carcinoma in situ sites and 17 moderate/sever dysplasia lesions were examined by a ratio fluorescence imaging system through a bronchoscope. The red/green ratios of carcinoma in situ sites and dysplasia sites were found to be 1.85 +/- 0.2 and 1.7 +/- 0.2 higher than that of normal sites. This was consistent with the simulation results.

Qu, Jianan Y.; MacAulay, Calum E.; Lam, Stephen; Palcic, Branko

1995-04-01

367

Optimal Taylor-Couette flow: radius ratio dependence  

NASA Astrophysics Data System (ADS)

Taylor-Couette flow with independently rotating inner (i) and outer (o) cylinders is explored numerically and experimentally to determine the effects of the radius ratio {\\eta} on the system response. Numerical simulations reach Reynolds numbers of up to Re_i=9.5 x 10^3 and Re_o=5x10^3, corresponding to Taylor numbers of up to Ta=10^8 for four different radius ratios {\\eta}=r_i/r_o between 0.5 and 0.909. The experiments, performed in the Twente Turbulent Taylor-Couette (T^3C) setup, reach Reynolds numbers of up to Re_i=2x10^6$ and Re_o=1.5x10^6, corresponding to Ta=5x10^{12} for {\\eta}=0.714-0.909. Effective scaling laws for the torque J^{\\omega}(Ta) are found, which for sufficiently large driving Ta are independent of the radius ratio {\\eta}. As previously reported for {\\eta}=0.714, optimum transport at a non-zero Rossby number Ro=r_i|{\\omega}_i-{\\omega}_o|/[2(r_o-r_i){\\omega}_o] is found in both experiments and numerics. Ro_opt is found to depend on the radius ratio and the driving of the system. At a driving in the range between {Ta\\sim3\\cdot10^8} and {Ta\\sim10^{10}}, Ro_opt saturates to an asymptotic {\\eta}-dependent value. Theoretical predictions for the asymptotic value of Ro_{opt} are compared to the experimental results, and found to differ notably. Furthermore, the local angular velocity profiles from experiments and numerics are compared, and a link between a flat bulk profile and optimum transport for all radius ratios is reported.

Ostilla-Mónico, Rodolfo; Huisman, Sander G.; Jannink, Tim J. G.; Van Gils, Dennis P. M.; Verzicco, Roberto; Grossmann, Siegfried; Sun, Chao; Lohse, Detlef

2014-05-01

368

Fluctuating silicate:nitrate ratios and coastal plankton food webs.  

PubMed

Marine diatoms require dissolved silicate to form an external shell, and their growth becomes Si-limited when the atomic ratio of silicate to dissolved inorganic nitrogen (Si:DIN) approaches 1:1, also known as the "Redfield ratio." Fundamental changes in the diatom-to-zooplankton-to-higher trophic level food web should occur when this ratio falls below 1:1 and the proportion of diatoms in the phytoplankton community is reduced. We quantitatively substantiate these predictions by using a variety of data from the Mississippi River continental shelf, a system in which the Si:DIN loading ratio has declined from around 3:1 to 1:1 during this century because of land-use practices in the watershed. We suggest that, on this shelf, when the Si:DIN ratio in the river decreases to less than 1:1, then (i) copepod abundance changes from >75% to <30% of the total mesozooplankton, (ii) zooplankton fecal pellets become a minor component of the in situ primary production consumed, and (iii) bottom-water oxygen consumption rates become less dependent on relatively fast-sinking (diatom-rich) organic matter packaged mostly as zooplankton fecal pellets. This coastal ecosystem appears to be a pelagic food web dynamically poised to be either a food web composed of diatoms and copepods or one with potentially disruptive harmful algal blooms. The system is directed between these two ecosystem states by Mississippi River water quality, which is determined by land-use practices far inland. PMID:9789038

Turner, R E; Qureshi, N; Rabalais, N N; Dortch, Q; Justi?, D; Shaw, R F; Cope, J

1998-10-27

369

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 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

370

Relativistic electron PXR and FPXR yield ratio  

NASA Astrophysics Data System (ADS)

The parametric X-radiation of relativistic electron crossing a single crystal plate is considered on the basis of dynamic diffraction theory in Laue geometry both in Bragg (PXR) and forward (FPXR) directions. Analytical expressions for spectral-angular density of these radiations in indicated directions are derived in general case of electron coulomb field asymmetric reflection from the target surface. The ratio of contributions of these radiation mechanisms into the total yield of the radiation is investigated. It is shown that the ratio of contributions of these radiation mechanisms can change sharply depending on the value of the reflection asymmetry.

Blazhevich, S.; Noskov, A.

2010-06-01

371

C IV line ratios in the sun  

NASA Astrophysics Data System (ADS)

Theoretical electron temperature-sensitive emission-line ratios are calculated with R-matrix analysis of electron-impact excitation rates for transitions in C IV. Two of the emission-line ratios are found to agree with observational data on the sun taken with a slitless spectrograph aboard Skylab, and the two remaining lines have inaccuracies that can be attributed to blending of the 312.43 A line. The agreement between the observational and analytical data lends credence to the accuracy of the atomic data used in the analysis.

Keenan, F. P.; Conlon, E. S.; Harra, L. K.; Burke, V. M.; Widing, K. G.

1992-01-01

372

Radioactive anomaly discrimination from spectral ratios  

DOEpatents

A method for discriminating a radioactive anomaly from naturally occurring radioactive materials includes detecting a first number of gamma photons having energies in a first range of energy values within a predetermined period of time and detecting a second number of gamma photons having energies in a second range of energy values within the predetermined period of time. The method further includes determining, in a controller, a ratio of the first number of gamma photons having energies in the first range and the second number of gamma photons having energies in the second range, and determining that a radioactive anomaly is present when the ratio exceeds a threshold value.

Maniscalco, James; Sjoden, Glenn; Chapman, Mac Clements

2013-08-20

373

VOLUME 80, NUMBER 21 P H Y S I C A L R E V I E W L E T T E R S 25 MAY 1998 X-Ray Scattering Study of the Surface Morphology of Au(111) during Ar1 Ion Irradiation  

E-print Network

this range with a thermocouple calibrated against the pyrometer. The Au(111) single crystal, with a miscut relation l t0.2760.02 . The aspect ratio of the features, assumed to be close packed [5,6], remains nearly- tures in the 100­220 ±C range were measured with an infrared pyrometer, and temperatures outside

Headrick, Randall L.

374

Relationship between leaf temperature and photosynthetic ratio of cherry tree  

NASA Astrophysics Data System (ADS)

We investigated the relations between leaf-air temperature and photosynthetic ratio of cherry trees in order to obtain the fundamental data for applying the biological information to the remote sensing system. Some branches of Prunus jamasakura were cut and put into the water pot prompt once per month from May to October 2001. We measured the surface temperature of ten leaves and photosynthetic ratio every five second for ten minutes every measurement air temperature condition at 20, 25, 30 and 35°C with 1000 PAR light intensity. Result as, there was recognized the small significantly relation between leaf temperature and photosynthetic ratio because leaf temperature is usually changed with air temperature. Although, there was recognized large significantly correlations between the difference of the leaf temperature and air temperature and photosynthetic ratio. It is thought that transpiring in healthy plants are active for absorption of water and it cause to drop the leaf temperature. This research showed that the health of cherry trees could be diagnosed for measurement of the difference of leaf and air temperature.

Nakashima, Atsushi; Ogura, Yasushi; Fujigaki, Motoharu; Tanikawa, Hiroki; Miwa, Masafumi

2003-03-01

375

Spectroscopic Measurement of Neutral Particle Influx Ratio on EAST  

NASA Astrophysics Data System (ADS)

The spectra of HeI (587.6 nm), H? (656.28 nm) and D? (656.1 nm) of the helium discharges as well as the normal deuterium discharges have been measured with two optical spectroscopic multi-channel analysis (OMA) systems on the experimental advanced superconducting tokamak (EAST). The influx ratio of the sum of H and D to He spectral lines and the influx ratio of H to D are given. In this way the ratio of hydrogen/deuterium ion (S/XB)H/D to (S/XB)He as well as (S/XB)H/D is not very sensitive to the variation in the edge density and temperature. The low-density helium discharges are operated in order to reduce the recycling hydrogen fluxes; however, the effect is not obvious. The possible reason is that the number of helium discharges is not enough and the content of hydrogen in the wall is still very abundant, which is caused by frequent wall conditionings and the vacuum leakage. The H/(H+D) ratio decreases quickly after one lithium coating and reduces to less than 10% using several accumulated lithium wall conditioning. It is found that the deposited He atoms on the carbon wall will remain at a low level after several D2 discharges.

Li, Yingying; Fu, Jia; Shi, Yuejiang; Zhang, Wei; Shen, Yongcai; Wang, Fudi; Lu, Bo; Huang, Juan; Zhang, Ling; Xu, Jingcui; Zhou, Qian

2013-06-01

376

Blowing Ratio Effects on Film Cooling Effectiveness  

E-print Network

The research focuses on testing the film cooling effectiveness on a gas turbine blade suction side surface. The test is performed on a five bladed cascade with a blow down facility. Four different blowing ratios are used in this study, which are 0...

Liu, Kuo-Chun

2010-01-14

377

Predicting Abnormal Returns Using Debt Ratios  

Microsoft Academic Search

This paper investigates the ability of the company capital structures to be used as a predictor for abnormal returns in the US stock market in the long run. The relationship between debt level and abnormal return over a three-year holding period is investigated. Robustness tests are carried out to determine the predictive ability of debt ratios when controlling for size

Brian Baturevich; Gulnur Muradoglu

378

Effects of Thermal Conductivity Ratio in  

E-print Network

Effects of Thermal Conductivity Ratio in Helium-Cooled Divertors B. H. Mills J. D. Rader D. L a correlation for from these experimental data o 4m Re D Calculating and Ref Brantley Mills - bmills-hydraulics and improving the thermal performance of various helium-cooled divertor designs Brantley Mills - bmills

379

Merger simulations with observed diversion ratios  

Microsoft Academic Search

A common approach to merger simulations used in antitrust cases is to calibrate demand from market shares and a few additional parameters. When the products involved in the merger case are differentiated along several dimensions, the resulting diversion ratios may be very different from those based upon market shares. This again may affect the predicted post-merger price effects. This article

Lars Mathiesen; Øivind Anti Nilsen; Lars Sørgard

2010-01-01

380

Merger simulations with observed diversion ratios  

Microsoft Academic Search

One approach to merger simulations used in antitrust cases is to calibrate demand from market shares and a few additional parameters. When the products involved in the merger case are differentiated along several dimensions, actual diversion ratios may be very different from those calculated from market shares. This again may affect the predicted post-merger price effects. This article shows how

Lars Mathiesen; Øivind Anti Nilsen; Lars Sørgard

2011-01-01

381

Perspectives on the basic reproductive ratio  

Microsoft Academic Search

The basic reproductive ratio, R0, is defined as the expected number of secondary infections arising from a single individual during his or her entire infectious period, in a population of susceptibles. This concept is fundamental to the study of epidemiology and within-host pathogen dynamics. Most importantly, R0 often serves as a threshold parameter that predicts whether an infection will spread.

J. M. Heffernan; R. J. Smith; L. M. Wahl

2005-01-01

382

Electronic branching ratio of the ? lepton  

E-print Network

Using data accumulated by the CLEO I detector operating at the Cornell Electron Storage Ring, we have measured the ratio R=?(??e?¯(e)?(?)) / ?(1) where ?(1) is the ? decay rate to final states with one charged particle. We find R=0...

Ammar, Raymond G.; Baringer, Philip S.; Coppage, Don; Davis, Robin E. P.; Kelly, M.; Kwak, Nowhan; Lam, H.

1992-06-01

383

Ratio method of measuring $w$ boson mass  

SciTech Connect

This dissertation describes an alternative method of measuring the W boson mass in D0 experiment. Instead of extracting M{sub W} from the fitting of W {yields} e{nu} fast Monte Carlo simulations to W {yields} e{nu} data as in the standard method, we make the direct fit of transverse mass between W {yields} e{nu} data and Z {yields} ee data. One of the two electrons from Z boson is treated as a neutrino in the calculation of transverse mass. In ratio method, the best fitted scale factor corresponds to the ratio of W and Z boson mass (M{sub W}/M{sub Z}). Given the precisely measured Z boson mass, W mass is directly fitted from W {yields} e{nu} and Z {yields} ee data. This dissertation demonstrates that ratio method is a plausible method of measuring the W boson mass. With the 1 fb{sup -1} D0 Run IIa dataset, ratio method gives M{sub W} = 80435 {+-} 43(stat) {+-} 26(sys) MeV.

Guo, Feng; /SUNY, Stony Brook

2010-08-01

384

Prediction of heptanes-plus equilibrium ratios from empirical correlations  

E-print Network

of the heavier hydrocarbon components. COMPARISON OF C7+ PROPERTY CALCULATIONS The next step in the procedure was to compare the accuracy of calculating the heptanes-plus property(ies) used by each correlation method. The aim was to determine whether... of the heptanes-plus properties was determined. The data consisted of ZIO inferred values of heptanes-plus properties from volatile oil systems and 175 values from retrograde gas systems. PREDICTION OF EQUILIBRIUM RATIOS The next step in this work was to test...

McKenna, Martin James

2012-06-07

385

CHARACTERIZING TRITIUM WASTE USING HELIUM RATIOS  

SciTech Connect

When routine sampling revealed greatly elevated tritium levels (3.14 x 105 Bq/L [8.5-million pCi/liter]) in the groundwater near a solid waste landfill at the Hanford Site, an innovative technique was used to assess the extent of the plume. Helium-3/helium-4 ratios, relative to ambient air-in-soil gas samples, were used to identify the tritium source and initially delineate the extent of the groundwater tritium plume. This approach is a modification of a technique developed in the late 1960s to age-date deep ocean water as part of the GEOSECS ocean monitoring program. Poreda, et al. (1) and Schlosser, et al. (2) applied this modified technique to shallow aquifers. A study was also conducted to demonstrate the concept of using helium-3 as a tool to locate vadose zone sources of tritium and tracking groundwater tritium plumes at Hanford (3). Seventy sampling points were installed around the perimeter and along four transects downgradient of the burial ground. Soil gas samples were collected, analyzed for helium isotopes, and helium-3/helium-4 ratios were calculated for these 70 points. The helium ratios indicated a vadose zone source of tritium along the northern edge of the burial ground that is likely the source of tritium in the groundwater. The helium ratios also indicate the groundwater plume is traveling east-northeast from the burial ground and that no up-gradient tritium sources are affecting the burial ground. Based on the helium ratio results, six downgradient groundwater sampling locations were identified to verify the tritium plume extent and groundwater tritium concentrations. The tritium results from the initial groundwater samples confirmed that elevated helium ratios were indicative of tritium contamination in the local groundwater. The measurement of helium isotopes in soil gas provided a rapid and cost- effective technique to define the shape and extent of tritium contamination from the burial ground. Using this soil gas sampling approach, the project team was able to identify areas where elevated tritium existed in groundwater without going to the time and expense of conducting conventional groundwater characterization sampling. The savings from this characterization approach were $1.4 million.

Ovink, R.W.; McMahon, W.J.; Borghese, J.V.; Olsen, K.B.

2003-02-27

386

Density-ratio robustness in dynamic state estimation  

NASA Astrophysics Data System (ADS)

The filtering problem is addressed by taking into account imprecision in the knowledge about the probabilistic relationships involved. Imprecision is modelled in this paper by a particular closed convex set of probabilities that is known with the name of density ratio class or constant odds-ratio (COR) model. The contributions of this paper are the following. First, we shall define an optimality criterion based on the squared-loss function for the estimates derived from a general closed convex set of distributions. Second, after revising the properties of the density ratio class in the context of parametric estimation, we shall extend these properties to state estimation accounting for system dynamics. Furthermore, for the case in which the nominal density of the COR model is a multivariate Gaussian, we shall derive closed-form solutions for the set of optimal estimates and for the credible region. Third, we discuss how to perform Monte Carlo integrations to compute lower and upper expectations from a COR set of densities. Then we shall derive a procedure that, employing Monte Carlo sampling techniques, allows us to propagate in time both the lower and upper state expectation functionals and, thus, to derive an efficient solution of the filtering problem. Finally, we empirically compare the proposed estimator with the Kalman filter. This shows that our solution is more robust to the presence of modelling errors in the system and that, hence, appears to be a more realistic approach than the Kalman filter in such a case.

Benavoli, Alessio; Zaffalon, Marco

2013-05-01

387

CFD assessment of orifice aspect ratio and mass flow ratio on jet mixing in rectangular ducts  

NASA Technical Reports Server (NTRS)

Isothermal CFD analysis was performed on axially opposed rows of jets mixing with cross flow in a rectangular duct. Laterally, the jets' centerlines were aligned with each other on the top and bottom walls. The focus of this study was to characterize the effects of orifice aspect ratio and jet-to-mainstream mass flow ratio on jet penetration and mixing. Orifice aspect ratios (L/W) of 4-to-1, 2-to-1, and 1-to-1, along with circular holes, were parametrically analyzed. Likewise, jet-to-mainstream mass flow ratios (MR) of 2.0, 0.5, and 0.25 were systematically investigated. The jet-to-mainstream momentum-flux ratio (J) was maintained at 36 for all cases, and the orifice spacing-to-duct height (S/H) was varied until optimum mixing was attained for each configuration. The numerical results showed that orifice aspect ratio (and likewise orifice blockage) had little effect on jet penetration and mixing. Based on mixing characteristics alone, the 4-to-1 slot was comparable to the circular orifice. The 4-to-1 slot has a smaller jet wake which may be advantageous for reducing emissions. However, the axial length of a 4-to-1 slot may be prohibitively long for practical application, especially for MR of 2.0. The jet-to-mainstream mass flow ratio had a more significant effect on jet penetration and mixing. For a 4-to-1 aspect ratio orifice, the design correlating parameter for optimum mixing (C = (S/H)(sq. root J)) varied from 2.25 for a mass flow ratio of 2.0 to 1.5 for a mass flow ratio of 0.25.

Bain, D. B.; Smith, C. E.; Holdeman, J. D.

1994-01-01

388

Polymeric Microring Resonator Enabling Variable Extinction Ratio  

NASA Astrophysics Data System (ADS)

A polymeric ring resonator filter enabling electrically variable extinction ratio has been implemented, incorporating a ring waveguide coupled to a bus waveguide and an electrode which is separated from it with a gap. When an electrical power is applied to the electrode, the refractive index of the polymers underneath it is lowered through the thermo-optic effect so that the guided-mode confinement in the ring is strengthened to reduce its bending loss. Consequently, for a constant bus-to-ring coupling the attenuation depth at resonant wavelengths could be adjusted electrically. As for the achieved performance, the extinction ratio was changed by ˜9 dB for the electrical power of ˜12 mW while the corresponding bending loss was improved by ˜86 dB/cm.

Song, Ju-Han; Kim, Do-Hwan; Lee, Sang-Shin

2007-02-01

389

Econometric models for predicting confusion crop ratios  

NASA Technical Reports Server (NTRS)

Results for both the United States and Canada show that econometric models can provide estimates of confusion crop ratios that are more accurate than historical ratios. Whether these models can support the LACIE 90/90 accuracy criterion is uncertain. In the United States, experimenting with additional model formulations could provide improved methods models in some CRD's, particularly in winter wheat. Improved models may also be possible for the Canadian CD's. The more aggressive province/state models outperformed individual CD/CRD models. This result was expected partly because acreage statistics are based on sampling procedures, and the sampling precision declines from the province/state to the CD/CRD level. Declining sampling precision and the need to substitute province/state data for the CD/CRD data introduced measurement error into the CD/CRD models.

Umberger, D. E.; Proctor, M. H.; Clark, J. E.; Eisgruber, L. M.; Braschler, C. B. (principal investigators)

1979-01-01

390

The HNC/HCN ratio in comets  

NASA Technical Reports Server (NTRS)

The abundance ratio of the isomers HCN and HNC has been investigated in comet Hale-Bopp (C/1995 O1) through observations of the J = 4-3 rotational transitions of both species for heliocentric distances 0.93 < r < 3 AU, both pre- and post-perihelion. After correcting for the optical depth of the stronger HCN line, we find that the column density ratio of HNC/HCN in our telescope beam increases significantly as the comet approaches the Sun. We compare this behavior to that predicted from an ion-molecule chemical model and conclude that the HNC is produced in significant measure by chemical processes in the coma; i.e., for comet Hale-Bopp, HNC is not a parent molecule sublimating from the nucleus.

Irvine, W. M.; Dickens, J. E.; Lovell, A. J.; Schloerb, F. P.; Senay, M.; Bergin, E. A.; Jewitt, D.; Matthews, H. E.; Ferris, J. P. (Principal Investigator)

1997-01-01

391

Theater SBI cost-effectiveness ratios  

SciTech Connect

To address M missiles spaced at intervals longer than the constillation reconstitution time t, the defense needs at the absentee ratio N{sub a} of SBIs to fill the belt plus the M SBIs needed for the intercepts; the resulting cost effectiveness scales as M/(M + N{sub a}). N{sub a} is large and CER small for small ranges and numbers of missiles. For several-hundred missile threats, CERs are greater than unity for ranges of interest.

Canavan, G.H.

1993-11-01

392

Noncircular, finite aspect ratio, local equilibrium model  

SciTech Connect

A tokamak equilibrium model, local to a flux surface, is introduced which is completely described in terms of nine parameters including aspect ratio, elongation, triangularity, and safety factor. By allowing controlled variation of each of these nine parameters, the model is particularly suitable for localized stability studies such as those carried out using the ballooning mode representation of the gyrokinetic equations. {copyright} {ital 1998 American Institute of Physics.}

Miller, R.L.; Chu, M.S.; Greene, J.M.; Lin-Liu, Y.R.; Waltz, R.E. [General Atomics, San Diego, California92186-5608 (United States)] [General Atomics, San Diego, California92186-5608 (United States)

1998-04-01

393

Isotope ratio determination in boron analysis  

Microsoft Academic Search

Traditionally, boron (B) isotope ratios have been determined using thermal ionization mass spectrometry (TIMS) and, to some\\u000a extent, secondary ion mass spectrometry (SIMS). Both TIMS and SIMS use a high-resolution mass analyzer, but differ in analyte\\u000a ionization methods. TIMS uses electrons from a hot filament, whereas SIMS employs an energetic primary ion beam of Ga+, Cs+, or O- for analyte

Ram N. Sah; Patrick H. Brown

1998-01-01

394

Symmetries and Periodicities of the Strehl Ratio  

Microsoft Academic Search

McCutchen's theorem relates the complex amplitude u(z) along the optical axis to the complex amplitude [ptilde](?,?) in the exit pupil. This relation is a Fourier transform. The assumptions made are that [ptilde] is rotationally symmetric and that the paraxial approximation applies. The normalized quantity |u(z)\\/u(0)|=S(z) is called the Strehl ratio. By using McCutchen's theorem we derive the necessary and sufficient

A. W. Lohmann; J. Ojeda-Castañeda

1984-01-01

395

Omniclassical Diffusion in Low Aspect Ratio Tokamaks  

SciTech Connect

Recently reported numerical results for axisymmetric devices with low aspect ratio A found radial transport enhanced over the expected neoclassical value by a factor of 2 to 3. In this paper, we provide an explanation for this enhancement. Transport theory in toroidal devices usually assumes large A, and that the ratio B{sub p}/B{sub t} of the poloidal to the toroidal magnetic field is small. These assumptions result in transport which, in the low collision limit, is dominated by banana orbits, giving the largest collisionless excursion of a particle from an initial flux surface. However in a small aspect ratio device one may have B{sub p}/B{sub t} {approx} 1, and the gyroradius may be larger than the banana excursion. Here, we develop an approximate analytic transport theory valid for devices with arbitrary A. For low A, we find that the enhanced transport, referred to as omniclassical, is a combination of neoclassical and properly generalized classical effects, which become dominant in the low-A, B{sub p}/B{sub t} {approx} 1 regime. Good agreement of the analytic theory with numerical simulations is obtained.

H.E. Mynick; R.B. White; D.A. Gates

2004-03-19

396

Modeling and clustering network-level urban traffic status based on traffic flow assignment ratios  

Microsoft Academic Search

The detected traffic data for single point or link cannot satisfy the needs for network-level traffic status information with the rapid development of the traffic control and guidance systems. This paper proposed a modeling and clustering method for network-level urban traffic status based on the dynamic traffic flow assignment ratios. The traffic assignment ratio matrix model integrates traffic status, topology

Li Qu; Jianming Hu; Yi Zhang

2010-01-01

397

Groundwater ''fast paths'' in the Snake River plain aquifer: Radiogenic isotope ratios as natural groundwater tracers  

Microsoft Academic Search

Preferential flow paths are expected in many groundwater systems and must be located because they can greatly affect contaminant transport. The fundamental characteristics of radiogenic isotope ratios in chemically evolving waters make them highly effective as preferential flow path indicators. These ratios tend to be more easily interpreted than solute-concentration data because their response to water-rock interaction is less complex.

Thomas M. Johnson; Robert C. Roback; Travis L. McLing; Thomas D. Bullen; Donald J. DePaolo; Christine Doughty; Randall J. Hunt; Robert W. Smith; L. DeWayne Cecil; Michael T. Murrell

2000-01-01

398

Groundwater ``fast paths'' in the Snake River Plain aquifer: Radiogenic isotope ratios as natural groundwater tracers  

Microsoft Academic Search

Preferential flow paths are expected in many groundwater systems and must be located because they can greatly affect contaminant transport. The fundamental characteristics of radiogenic isotope ratios in chemically evolving waters make them highly effective as preferential flow path indicators. These ratios tend to be more easily interpreted than solute-concentration data because their response to water-rock interaction is less complex.

Thomas M. Johnson; Robert C. Roback; Travis L. McLing; Thomas D. Bullen; Donald J. Depaolo; Christine Doughty; Randall J. Hunt; Robert W. Smith; L. Dewayne Cecil; Michael T. Murrell

2000-01-01

399

Gametocyte sex ratio in single-clone infections of the malaria parasite Plasmodium mexicanum  

E-print Network

Gametocyte sex ratio in single-clone infections of the malaria parasite Plasmodium mexicanum A 12 July 2010) SUMMARY Sex ratio theory predicts that malaria parasites should bias gametocyte system later in the infection. Recent experimental studies reveal genetic variation for gametocyte sex

Schall, Joseph J.

400

Tracking Civilian Casualties in Combat Zones using Civilian Battle Damage Assessment Ratios  

Microsoft Academic Search

The Civilian Battle Damage Assessment Ratio (CBDAR) is a method for assessing and tracking proportional patterns of civilian casualties from combat. CBDARs can be applied by both military forces and humanitarian organisations towards the common goal of minimising the civilian impact of conflict. These ratios complement absolute numbers on casualties, are easily integrated into existing assessment systems, and can track

Ewan Cameron; Michael Spagat; Madelyn Hsiao-Rei Hicks

2009-01-01

401

Bound-ratio minimization of filter bank frames by periodic precoding  

Microsoft Academic Search

Frame (upper and lower) bound ratio is a key factor of numerical stability of frame systems. While tight frames, of which the minimal ratio 1 is achieved, are much preferred in many practical situations, they may not be easily (even impossible) designed due to other criteria (for example, good subband frequency shape). In these situations, we may find alternative methods

Li Chai; Jingxin Zhang

2011-01-01

402

Quantification of Nanoscale Density Fluctuations in Biological Cells/Tissues: Inverse Participation Ratio (IPR) Analysis of  

E-print Network

Ratio (IPR) Analysis of Transmission Electron Microscopy Images and Implications for Early-Stage Cancer analysis of the inverse participation ratio (IPR) of the eigenfunctions of these optical lattices at the nanoscales. First, the IPR analysis is validated in experiments with models of disordered systems fabricated

Pradhan, Prabhakar

403

High aspect ratio- and 3D- printing of freestanding sophisticated structures  

Microsoft Academic Search

This paper presents work towards a printing technology which provides the fabrication foundation of high aspect ratio- and 3D freestanding sophisticated structures with an aspect ratio over 150. Via connection of the printing technology and a computer aided design system a fast and cost-efficient fabrication process for prototypes manufacture and low volume production. These printing process in combination with mold

A. Kain; C. Mueller; H. Reinecke

2009-01-01

404

Facultative sex ratio adjustment in response to male tarsus length in the Varied Tit Parus varius  

Microsoft Academic Search

During the last decade, evidence from a number of studies has suggested systematic devi- ations from a 1 : 1 primary sex ratio in birds, in spite of the fact that birds have chromosomal sex determination systems; the mechanism of sex allocation is not fully understood. How- ever, it still remains uncertain whether adaptive manipulations of primary sex ratio occur,

Noriyuki Yamaguchi; Katsura K. Kawano; Kazuhiro Eguchi; Tetsukazu Yahara

2004-01-01

405

Influence of latent toxoplasmosis on the secondary sex ratio S. KAN KOVA 1  

E-print Network

2007; first published online 26 July 2007) SUMMARY The sex ratio may be influenced by many factorsInfluence of latent toxoplasmosis on the secondary sex ratio in mice S. KAN KOVA´ 1 , P. KODYM2 , D, such as stress and immunosuppression, age of parents, parity and sex of preceding siblings. In animal systems

Flegr, Jaroslav

406

A heritable component in sex ratio and caste determination in a Cardiocondyla ant  

PubMed Central

Studies on sex ratios in social insects provide among the most compelling evidence for the importance of kin selection in social evolution. The elegant synthesis of Fisher's sex ratio principle and Hamilton's inclusive fitness theory predicts that colony-level sex ratios vary with the colonies' social and genetic structures. Numerous empirical studies in ants, bees, and wasps have corroborated these predictions. However, the evolutionary optimization of sex ratios requires genetic variation, but one fundamental determinant of sex ratios - the propensity of female larvae to develop into young queens or workers ("queen bias") - is thought to be largely controlled by the environment. Evidence for a genetic influence on sex ratio and queen bias is as yet restricted to a few taxa, in particular hybrids. Because of the very short lifetime of their queens, ants of the genus Cardiocondyla are ideal model systems for the study of complete lifetime reproductive success, queen bias, and sex ratios. We found that lifetime sex ratios of the ant Cardiocondyla kagutsuchi have a heritable component. In experimental single-queen colonies, 22 queens from a genetic lineage with a highly female-biased sex ratio produced significantly more female-biased offspring sex ratios than 16 queens from a lineage with a more male-biased sex ratio (median 91.5% vs. 58.5% female sexuals). Sex ratio variation resulted from different likelihood of female larvae developing into sexuals (median 50% vs. 22.6% female sexuals) even when uniformly nursed by workers from another colony. Consistent differences in lifetime sex ratios and queen bias among queens of C. kagutsuchi suggest that heritable, genetic or maternal effects strongly affect caste determination. Such variation might provide the basis for adaptive evolution of queen and worker strategies, though it momentarily constrains the power of workers and queens to optimize caste ratios. PMID:19863794

Frohschammer, Sabine; Heinze, Jürgen

2009-01-01

407

Guidelines and recommended terms for expression of stable-isotope-ratio and gas-ratio measurement results  

USGS Publications Warehouse

To minimize confusion in the expression of measurement results of stable isotope and gas-ratio measurements, recommendations based on publications of the Commission on Isotopic Abundances and Atomic Weights of the International Union of Pure and Applied Chemistry (IUPAC) are presented. Whenever feasible, entries are consistent with the Système International d'Unités, the SI (known in English as the International System of Units), and the third edition of the International Vocabulary of Basic and General Terms in Metrology (VIM, 3rd edition). The recommendations presented herein are approved by the Commission on Isotopic Abundances and Atomic Weights and are designed to clarify expression of quantities related to measurement of isotope and gas ratios to ensure that quantity equations instead of numerical value equations are used for quantity definitions. Examples of column headings consistent with quantity calculus (also called the algebra of quantities) and examples of various deprecated usages connected with the terms recommended are presented.

Coplen, Tyler B.

2011-01-01

408

Emergy-based indices and ratios to evaluate sustainability: monitoring economies and technology toward environmentally sound innovation  

Microsoft Academic Search

This paper provides a reference set of indices based on emergy, for the evaluation of ecotechnological processes and whole economies. Indices of emergy yield ratio (EYR), environmental loading ratio (ELR), and emergy investment ratio (EIR), among others, are stressed, and a new index the emergy sustainability index (ESI) is defined. The emergy indices for a given system are shown to

M. T Brown; S Ulgiati

1997-01-01

409

Cytoplasm-to-myonucleus ratios following microgravity  

NASA Technical Reports Server (NTRS)

The cytoplasmic volume-to-myonucleus ratio in the tibialis anterior and gastrocnemius muscles of juvenile rats after 5.4 days of microgravity was studied. Three groups of rats (n = 8 each) were used. The experimental group (space rats) was flown aboard the space shuttle Discovery (NASA, STS-48), while two ground-based groups, one hindlimb suspended (suspended rats), one non-suspended (control), served as controls. Single fibre analysis revealed a significant decrease in cross-sectional area (microns2) in the gastrocnemius for both the space and the suspended rats; in the tibialis anterior only the suspended rats showed a significant decrease. Myonuclei counts (myonuclei per mm) in both the tibialis anterior and gastrocnemius were significantly increased in the space rats but not in the suspended rats. The mean myonuclear volume (individual nuclei: microns3) in tibialis anterior fibres from the space rats, and in gastrocnemius fibres from both the space and the suspended rats, was significantly lower than that in the respective control group. Estimation of the total myonuclear volume (microns3 per.mm), however, revealed no significant differences between the three groups in either the tibialis anterior or gastrocnemius. The described changes in the cross-sectional area and myonuclei numbers resulted in significant decreases in the cytoplasmic volume-to-myonucleus ratio (microns3 x 10(3)) in both muscles and for both space and suspended rats (tibialis anterior; 15.6 +/- 0.6 (space), 17.2 +/- 1.0 (suspended), 20.8 +/- 0.9 (control): gastrocnemius; 13.4 +/- 0.4 (space) and 14.9 +/- 1.1 (suspended) versus 18.1 +/- 1.1 (control)). These results indicate that even short periods of unweighting due to microgravity or limb suspension result in changes in skeletal muscle fibres which lead to significant decreases in the cytoplasmic volume-to-myonucleus ratio.

Kasper, C. E.; Xun, L.

1996-01-01

410

Using continuous DNA interpretation methods to revisit likelihood ratio behaviour.  

PubMed

Continuous DNA interpretation systems make use of more information from DNA profiles than analysts have previously been able to with binary, threshold based systems. With these new continuous DNA interpretation systems and a new, more powerful, DNA profiling kit (GlobalFiler) there is an opportunity to re-examine the behaviour of a commonly used statistic in forensic science, the likelihood ratio (LR). The theoretical behaviour of the LR has been known for some time, although in many instances the behaviour has not been able to be thoroughly demonstrated due to limitations of the biological and mathematical models being used. In this paper the effects of profile complexity, replicate amplifications, assuming contributors, adding incorrect information, and adding irrelevant information to the calculation of the LR are explored. The empirical results are compared to theoretical expectations and explained. The work finishes with the results being used to dispel common misconceptions around reliability, accuracy, informativeness and reproducibility. PMID:24727432

Taylor, Duncan

2014-07-01

411

New "Golden" Ratios for Facial Beauty  

PubMed Central

In four experiments, we tested the existence of an ideal facial feature arrangement that could optimize the attractiveness of any face given its facial features. Participants made paired comparisons of attractiveness between faces with identical facial features but different eye-mouth distances and different interocular distances. We found that although different faces have varying attractiveness, individual attractiveness is optimized when the face’s vertical distance between the eyes and the mouth is approximately 36% of its length, and the horizontal distance between the eyes is approximately 46% of the face’s width. These “new” golden ratios match those of an average face. PMID:19896961

Pallett, Pamela M.; Link, Stephen; Lee, Kang

2009-01-01

412

High aspect ratio, remote controlled pumping assembly  

DOEpatents

A miniature dual syringe-type pump assembly is described which has a high aspect ratio and which is remotely controlled, for use such as in a small diameter penetrometer cone or well packer used in water contamination applications. The pump assembly may be used to supply and remove a reagent to a water contamination sensor, for example, and includes a motor, gearhead and motor encoder assembly for turning a drive screw for an actuator which provides pushing on one syringe and pulling on the other syringe for injecting new reagent and withdrawing used reagent from an associated sensor. 4 figs.

Brown, S.B.; Milanovich, F.P.

1995-11-14

413

6.RP Ratio of boys to girls  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: The ratio of the number of boys to the number of girls at school is 4:5. What fraction of the students are boys? If there are 120 boys, how many studen...

414

Sex ratio, sex change, and natural selection.  

PubMed Central

We describe the analogy between the theory of natural selection on sex ratio in newborn gonochores (which will not change sex), and on the age of sex change in sequential hermaphrodites (which are all born into one sex and change to the other later on). We also discuss the conditions under which natural selection favors sequential hermaphrodites over gonochores and vice versa. We show that, in a nearly stable population of nearly constant age composition, selection favors a rare mutant if it increases the prospective reproduction of its newborn bearers that are (or while they are) members of one sex by a percentage exceeding the percentage loss to the other sex. PMID:1068478

Leigh, E G; Charnov, E L; Warner, R R

1976-01-01

415

12 CFR 615.5206 - Permanent capital ratio computation.  

Code of Federal Regulations, 2010 CFR

... false Permanent capital ratio computation. 615.5206...5206 Permanent capital ratio computation. (a) The institution's permanent capital ratio is determined on the basis...accordance with generally accepted accounting principles except...

2010-01-01

416

12 CFR 3.6 - Minimum capital ratios.  

Code of Federal Regulations, 2010 CFR

... (b) Total assets leverage ratio. All national banks must... (c) Additional leverage ratio requirement. An institution...high asset quality; high liquidity; and well managed on-and...the minimum Tier 1 leverage ratio is 4 percent. In all...

2010-01-01

417

Instability of low viscosity elliptic jets with varying aspect ratio  

NASA Astrophysics Data System (ADS)

In this work an analytical description of capillary instability of liquid elliptic jets with varying aspect ratio is presented. Linear stability analysis in the long wave approximation with negligible gravitational effects is employed. Elliptic cylindrical coordinate system is used and perturbation velocity potential substituted in the Laplace equation to yield Mathieu and Modified Mathieu differential equations. The dispersion relation for elliptical orifices of any aspect ratio is derived and validated for axisymmetric disturbances with m = 0, in the limit of aspect ratio, ?= 1, i.e. the case of a circular jet. As Mathieu functions and Modified Mathieu function solutions converge to Bessel's functions in this limit the Rayleigh-Plateau instability criterion is met. Also, stability of solutions corresponding to asymmetric disturbances for the kink mode, m = 1 and flute modes corresponding to m >=2 is discussed. Experimental data from earlier works is used to compare observations made for elliptical orifices with ?1. This novel approach aims at generalizing the results pertaining to cylindrical jets with circular cross section leading to better understanding of breakup in liquid jets of various geometries.

Kulkarni, Varun

2011-11-01

418

Airborne characterization of smoke marker ratios from prescribed burning  

NASA Astrophysics Data System (ADS)

A Particle-into-Liquid Sampler - Total Organic Carbon and fraction collector system was flown aboard aTwin Otter aircraft sampling prescribed burning emissions in South Carolina in November2011 to obtain smoke marker measurements. The fraction collector provided 2 min time-integrated off-line samples for carbohydrate (i.e., smoke markers levoglucosan, mannosan, galactosan) analysis by high-performance anion-exchange chromatography with pulsed amperometric detection. Each fire location appeared to have aunique ? levoglucosan / ? water-soluble organic carbon (WSOC) ratio (RF01/RF02/RF03/RF05 = 0.163 ± 0.007 ?g C ?g C-1, RF08 = 0.115 ± 0.011 ?g C ?g C-1, RF09A = 0.072 ± 0.028 ?g C ?g C-1, RF09B = 0.042 ± 0.008 ?g C ?g C-1). These ratios were comparable to those obtained from controlled laboratory burns and suggested that the emissions sampled during RF01/RF02/RF03/RF05 were dominated by the burning of grasses, RF08 by leaves, RF09A by needles, and RF09B by marsh grasses. These findings were further supported by the ? galactosan / ? levoglucosan ratios (RF01/RF02/RF03/RF05 = 0.067 ± 0.004 ?g ?g-1, RF08 = 0.085 ± 0.009 ?g ?g-1, RF09A = 0.101 ± 0.029 ?g ?g-1) obtained as well as by the ground-based fuel and filter sample analyses during RF01/RF02/RF03/RF05. Differences between ? potassium / ? levoglucosan ratios obtained for these prescribed fires vs. laboratory-scale measurements suggest that some laboratory burns may not accurately represent potassium emissions from prescribed burns. The ? levoglucosan / ? WSOC ratio had no clear dependence on smoke age or fire dynamics suggesting that this ratio is more dependent on the type of fuel being burned. Levoglucosan was stable over a timescale of at least 1.5 h and could be useful to help estimate the air quality impacts of biomass burning.

Sullivan, A. P.; May, A. A.; Lee, T.; McMeeking, G. R.; Kreidenweis, S. M.; Akagi, S. K.; Yokelson, R. J.; Urbanski, S. P.; Collett, J. L., Jr.

2014-05-01

419

Airborne characterization of smoke marker ratios from prescribed burning  

NASA Astrophysics Data System (ADS)

A Particle-Into-Liquid Sampler - Total Organic Carbon (PILS-TOC) and fraction collector system was flown aboard a Twin Otter aircraft sampling prescribed burning emissions in South Carolina in November 2011 to obtain smoke marker measurements. The fraction collector provided 2 min time-integrated offline samples for carbohydrate (i.e., smoke markers levoglucosan, mannosan, and galactosan) analysis by high-performance anion-exchange chromatography with pulsed amperometric detection. Each fire location appeared to have a unique ?levoglucosan/?water-soluble organic carbon (WSOC) ratio (RF01/RF02/RF03/RF05 = 0.163 ± 0.007 ?g C ?g-1 C, RF08 = 0.115 ± 0.011 ?g C ?g-1 C, RF09A = 0.072 ± 0.028 ?g C ?g-1 C, and RF09B = 0.042 ± 0.008 ?g C ?g-1 C, where RF means research flight). These ratios were comparable to those obtained from controlled laboratory burns and suggested that the emissions sampled during RF01/F02/RF03/RF05 were dominated by the burning of grasses, RF08 by leaves, RF09A by needles, and RF09B by marsh grasses. These findings were further supported by the ?galactosan/?levoglucosan ratios (RF01/RF02/RF03/RF05 = 0.067 ± 0.004 ?g ?g-1, RF08 = 0.085 ± 0.009 ?g ?g-1, and RF09A = 0.101 ± 0.029 ?g ?g-1) obtained as well as by the ground-based fuel and filter sample analyses during RF01/RF02/RF03/RF05. Differences between ?potassium/?levoglucosan ratios obtained for these prescribed fires vs. laboratory-scale measurements suggest that some laboratory burns may not accurately represent potassium emissions from prescribed burns. The ?levoglucosan/?WSOC ratio had no clear dependence on smoke age or fire dynamics suggesting that this ratio is more dependent on the type of fuel being burned. Levoglucosan was stable over a timescale of at least 1.5 h and could be useful to help estimate the air quality impacts of biomass burning.

Sullivan, A. P.; May, A. A.; Lee, T.; McMeeking, G. R.; Kreidenweis, S. M.; Akagi, S. K.; Yokelson, R. J.; Urbanski, S. P.; Collett, J. L., Jr.

2014-10-01

420

Thermal hydraulic design and analysis of a large lead-cooled reactor with flexible conversion ratio  

E-print Network

This thesis contributes to the Flexible Conversion Ratio Fast Reactor Systems Evaluation Project, a part of the Nuclear Cycle Technology and Policy Program funded by the Department of Energy through the Nuclear Energy ...

Nikiforova, Anna S., S.M. Massachusetts Institute of Technology

2008-01-01

421

An automotive engine model for air-fuel ratio control using cylinder pressure information  

E-print Network

Increasingly strict emission standards require very accurate and fast air-fuel ratio (AFR) control in combustion engines. This thesis addresses the design methodology currently used for synthesizing a control system for an automotive internal...

Nana, Emmanuel Tomdio

2012-06-07

422

Air/fuel ratio visualization in a diesel spray  

NASA Astrophysics Data System (ADS)

To investigate some features of high pressure diesel spray ignition, we have applied a newly developed planar imaging system to a spray in an engine-fed combustion bomb. The bomb is designed to give flow characteristics similar to those in a direct injection diesel engine yet provide nearly unlimited optical access. A high pressure electronic unit injector system with on-line manually adjustable main and pilot injection features was used. The primary scalar of interest was the local air/fuel ratio, particularly near the spray plumes. To make this measurement quantitative, we have developed a calibration LIF technique. The development of this technique is the key contribution of this dissertation. The air/fuel ratio measurement was made using biacetyl as a seed in the air inlet to the engine. When probed by a tripled Nd:YAG laser the biacetyl fluoresces, with a signal proportional to the local biacetyl concentration. This feature of biacetyl enables the fluorescent signal to be used as as indicator of local fuel vapor concentration. The biacetyl partial pressure was carefully controlled, enabling estimates of the local concentration of air and the approximate local stoichiometry in the fuel spray. The results indicate that the image quality generated with this method is sufficient for generating air/fuel ratio contours. The processes during the ignition delay have a marked effect on ignition and the subsequent burn. These processes, vaporization and pre-flame kinetics, very much depend on the mixing of the air and fuel. This study has shown that poor mixing and over-mixing of the air and fuel will directly affect the type of ignition. An optimal mixing arrangement exists and depends on the swirl ratio in the engine, the number of holes in the fuel injector and the distribution of fuel into a pilot and main injection. If a short delay and a diffusion burn is desired, the best mixing parameters among those surveyed would be a high swirl ratio, a 4-hole nozzle and a small pilot. This arrangement provided the best combination of short ignition delay and diffusion burn for the majority of cases.

Carabell, Kevin David

1993-01-01

423

Parasite Stress Predicts Offspring Sex Ratio  

PubMed Central

In this study, I predict that the global variation of offspring sex ratio might be influenced in part by the level of parasite stress. From an energetic standpoint, higher gestational costs of producing a male offspring could decrease male births in a population with limited resources. This implies that, any factor that limits the parental resources could be expected to favor female offspring production. Human sex ratio at birth (SRB) is believed to be influenced by numerous socioeconomic, biological, and environmental factors. Here, I test a prediction that parasite stress, by virtue of its effects on the general health condition, may limit the parental investment ability and therefore could influence the SRB at the population level. The statistical analysis supports this prediction, and show that the level of parasite stress has a significant inverse relation with population SRB across the world. Further, this relation is many-folds stronger than the association of SRB with other factors, like; polygyny, fertility, latitude, and son-preference. Hence, I propose that condition affecting ability of parasites (but not adaptive significance) could be a likely causal basis for the striking variation of SRB across populations. PMID:23049967

Dama, Madhukar Shivajirao

2012-01-01

424

Finger Length Ratios in Serbian Transsexuals  

PubMed Central

Atypical prenatal hormone exposure could be a factor in the development of transsexualism. There is evidence that the 2nd and 4th digit ratio (2D?:?4D) associates negatively with prenatal testosterone and positively with estrogens. The aim was to assess the difference in 2D?:?4D between female to male transsexuals (FMT) and male to female transsexuals (MFT) and controls. We examined 42?MFT, 38?FMT, and 45 control males and 48 control females. Precise measurements were made by X-rays at the ventral surface of both hands from the basal crease of the digit to the tip using vernier calliper. Control male and female patients had larger 2D?:?4D of the right hand when compared to the left hand. Control male's left hand ratio was lower than in control female's left hand. There was no difference in 2D?:?4D between MFT and control males. MFT showed similar 2D?:?4D of the right hand with control women indicating possible influencing factor in embryogenesis and consequently finger length changes. FMT showed the lowest 2D?:?4D of the left hand when compared to the control males and females. Results of our study go in favour of the biological aetiology of transsexualism. PMID:24982993

Vujovic, Svetlana; Popovic, Srdjan; Mrvosevic Marojevic, Ljiljana; Ivovic, Miomira; Tancic-Gajic, Milina; Stojanovic, Milos; Marina, Ljiljana V.; Barac, Marija; Barac, Branko; Kovacevic, Milena; Duisin, Dragana; Barisic, Jasmina; Djordjevic, Miroslav L.; Micic, Dragan

2014-01-01

425

Ultra-High Bypass Ratio Jet Noise  

NASA Technical Reports Server (NTRS)

The jet noise from a 1/15 scale model of a Pratt and Whitney Advanced Ducted Propulsor (ADP) was measured in the United Technology Research Center anechoic research tunnel (ART) under a range of operating conditions. Conditions were chosen to match engine operating conditions. Data were obtained at static conditions and at wind tunnel Mach numbers of 0.2, 0.27, and 0.35 to simulate inflight effects on jet noise. Due to a temperature dependence of the secondary nozzle area, the model nozzle secondary to primary area ratio varied from 7.12 at 100 percent thrust to 7.39 at 30 percent thrust. The bypass ratio varied from 10.2 to 11.8 respectively. Comparison of the data with predictions using the current Society of Automotive Engineers (SAE) Jet Noise Prediction Method showed that the current prediction method overpredicted the ADP jet noise by 6 decibels. The data suggest that a simple method of subtracting 6 decibels from the SAE Coaxial Jet Noise Prediction for the merged and secondary flow source components would result in good agreement between predicted and measured levels. The simulated jet noise flight effects with wind tunnel Mach numbers up to 0.35 produced jet noise inflight noise reductions up to 12 decibels. The reductions in jet noise levels were across the entire jet noise spectra, suggesting that the inflight effects affected all source noise components.

Low, John K. C.

1994-01-01

426

Ultra-high bypass ratio jet noise  

NASA Astrophysics Data System (ADS)

The jet noise from a 1/15 scale model of a Pratt and Whitney Advanced Ducted Propulsor (ADP) was measured in the United Technology Research Center anechoic research tunnel (ART) under a range of operating conditions. Conditions were chosen to match engine operating conditions. Data were obtained at static conditions and at wind tunnel Mach numbers of 0.2, 0.27, and 0.35 to simulate inflight effects on jet noise. Due to a temperature dependence of the secondary nozzle area, the model nozzle secondary to primary area ratio varied from 7.12 at 100 percent thrust to 7.39 at 30 percent thrust. The bypass ratio varied from 10.2 to 11.8 respectively. Comparison of the data with predictions using the current Society of Automotive Engineers (SAE) Jet Noise Prediction Method showed that the current prediction method overpredicted the ADP jet noise by 6 decibels. The data suggest that a simple method of subtracting 6 decibels from the SAE Coaxial Jet Noise Prediction for the merged and secondary flow source components would result in good agreement between predicted and measured levels. The simulated jet noise flight effects with wind tunnel Mach numbers up to 0.35 produced jet noise inflight noise reductions up to 12 decibels. The reductions in jet noise levels were across the entire jet noise spectra, suggesting that the inflight effects affected all source noise components.

Low, John K. C.

1994-10-01

427

Emission Ratios from SCIAMACHY simultaneous measurements  

NASA Astrophysics Data System (ADS)

The spectra of reflected and backscattered solar radiation as measured by SCIAMACHY in nadir observation mode in the UV/visible/near-infrared/short-wave-infrared spectral region contain information on the vertical columns of numerous air pollutants and therefore provide a large-scale perspective on spacious and uncertain pollution sources like biomass burnings. It will be shown that under a number of reasonable assumptions we can obtain a quantitative charac-teristics of biomass burning emissions in terms of emission ratios (ER) using only the averages of the atmospheric gas columns retrieved from the space-based simultaneous measurements. Considering for example the SCIAMACHY carbon monoxide (CO), taken as a reference car-bon component, together with the SCIAMACHY formaldehyde (HCHO) and nitrogen dioxide (NO2) columns in the scope of a well established emission quantification method we calcu-late the emission ratios, CO/HCHO and CO/NO2, over large biomass burning events in 2004 (established with the help of the AATSR fire counts product). We show that the calculated ER values are in reasonable agreement with the values obtained locally over similar biomass burning events reported in the literature. In addition, we discuss the relatively large values over the boreal forest fires in Alaska and Siberia, where ER values from local measurements were not yet reported.

Khlystova, Iryna; Richter, Andreas; Wittrock, Folkard; Burrows, John P.; Buchwitz, Michael; Bovensmann, Heinrich

428

The influence of aspect ratio and roughness on flowability  

NASA Astrophysics Data System (ADS)

Poor flowability hampers particle processing in many instances; causing a reduction in process efficiency, increased manufacturing costs and leading to excessive waste. The resistance of powders to flow can arise from a number of particle properties, such as cohesion, friction, shape and roughness. The objective of this work is to determine to what extent the flowability of powders is affected by their particle shape and roughness. The Distinct Element Method (DEM) is used to precisely control the shape and roughness of the particles. Needle-like particles are represented by the method of overlapping spheres, introduced by Favier et al. (1999). The fractional overlap of these spheres is varied, along with the number of spheres per particle, to produce particles with ranges of roughness and aspect ratio, respectively. The flowability of these particles is assessed by simulating two systems: a standard shear box, and indentation of a powder bed with a spherical indenter - introduced by Hassanpour and Ghadiri (2007). The particles are generated with a random orientation and allowed to settle under gravity before they are consolidated by a platen to a desired stress. The results show that particles with a large aspect ratio experience reduced shear stresses. This behaviour may be caused by particles aligning, thus allowing them to slide past one another more easily. An increase in particle roughness promotes interlocking, for a given aspect ratio rougher particles are shown to experience increased shear stresses. This work provides a robust analysis of the influence of aspect ratio and roughness on the flowability of powders, thus allowing the flowability of real materials to be better understood.

Hare, Colin; Ghadiri, Mojtaba

2013-06-01

429

Stress ratio effect on cyclic debonding in adhesively bonded composite joints  

NASA Technical Reports Server (NTRS)

A study was conducted to investigate the stress ratio effect on cyclic debond growth behavior in adhesively bonded composite joints. The system studied consisted of graphite/epoxy adherends