These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Vertical cup-to-disc ratio measurement for diagnosis of glaucoma on fundus images  

NASA Astrophysics Data System (ADS)

Glaucoma is a leading cause of permanent blindness. Retinal fundus image examination is useful for early detection of glaucoma. In order to evaluate the presence of glaucoma, the ophthalmologists determine the cup and disc areas and they diagnose glaucoma using a vertical cup-to-disc ratio. However, determination of the cup area is very difficult, thus we propose a method to measure the cup-to-disc ratio using a vertical profile on the optic disc. First, the blood vessels were erased from the image and then the edge of optic disc was then detected by use of a canny edge detection filter. Twenty profiles were then obtained around the center of the optic disc in the vertical direction on blue channel of the color image, and the profile was smoothed by averaging these profiles. After that, the edge of the cup area on the vertical profile was determined by thresholding technique. Lastly, the vertical cup-to-disc ratio was calculated. Using seventy nine images, including twenty five glaucoma images, the sensitivity of 80% and a specificity of 85% were achieved with this method. These results indicated that this method can be useful for the analysis of the optic disc in glaucoma examinations.

Hatanaka, Yuji; Noudo, Atsushi; Muramatsu, Chisako; Sawada, Akira; Hara, Takeshi; Yamamoto, Tetsuya; Fujita, Hiroshi

2010-03-01

2

Cup-To-Disc Ratio Of The Optic Disc By Image Analysis To Assist Diagnosis Of Glaucoma Risk And Evolution  

NASA Astrophysics Data System (ADS)

This work builds an image analysis algorithm to give assistance in the cup to disc ratio estimation of glaucomatous eyes. Often the contours of both the optic cup and disc are faint and intersected by entangled veins that make it difficult to draw their silhouettes. The algorithm, which takes into account the viewing conditions of the specialist, is based on the information of color, the color differences between neighbor pixels and the geometry of the areas involved.

Valencia, Edison; Millán, María S.; Kotynski, Rafal

2006-10-01

3

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

4

Automated determination of cup-to-disc ratio for classification of glaucomatous and normal eyes on stereo retinal fundus images.  

PubMed

Early diagnosis of glaucoma, which is the second leading cause of blindness in the world, can halt or slow the progression of the disease. We propose an automated method for analyzing the optic disc and measuring the cup-to-disc ratio (CDR) on stereo retinal fundus images to improve ophthalmologists' diagnostic efficiency and potentially reduce the variation on the CDR measurement. The method was developed using 80 retinal fundus image pairs, including 25 glaucomatous, and 55 nonglaucomatous eyes, obtained at our institution. A disc region was segmented using the active contour method with the brightness and edge information. The segmentation of a cup region was performed using a depth map of the optic disc, which was reconstructed on the basis of the stereo disparity. The CDRs were measured and compared with those determined using the manual segmentation results by an expert ophthalmologist. The method was applied to a new database which consisted of 98 stereo image pairs including 60 and 30 pairs with and without signs of glaucoma, respectively. Using the CDRs, an area under the receiver operating characteristic curve of 0.90 was obtained for classification of the glaucomatous and nonglaucomatous eyes. The result indicates potential usefulness of the automated determination of CDRs for the diagnosis of glaucoma. PMID:21950923

Muramatsu, Chisako; Nakagawa, Toshiaki; Sawada, Akira; Hatanaka, Yuji; Yamamoto, Tetsuya; Fujita, Hiroshi

2011-09-01

5

The Path to Open-Angle Glaucoma Gene Discovery: Endophenotypic Status of Intraocular Pressure, Cup-to-Disc Ratio, and Central Corneal Thickness  

PubMed Central

Purpose. Primary open-angle glaucoma (POAG) is a complex disease with a genetic architecture that can be simplified through the investigation of individual traits underlying disease risk. It has been well studied in twin models, and this study was undertaken to investigate the heritability of some of these key endophenotypes in extended pedigrees. Methods. These data are derived from a large, multicenter study of extended, Caucasian POAG families from Australia and the United States. The study included 1181 people from 22 extended pedigrees. Variance components modeling was used to determine the heritabilities of maximum intraocular pressure (IOP), maximum vertical cup-to-disc ratio (VCDR), and mean central corneal thickness (CCT). Bivariate quantitative genetic analysis between these eye-related phenotypes and POAG itself was performed to determine whether any of these traits represent true endophenotypes. Results. Heritability estimates for IOP, VCDR, and CCT (0.42, 0.66, and 0.72, respectively) were significant and show strong concordance with data in previous studies. Bivariate analysis revealed that both IOP (RhoG = 0.80; P = 9.6 × 10?6) and VCDR (RhoG = 0.76; P = 4.8 × 10?10) showed strong evidence of genetic correlation with POAG susceptibility. These two traits also correlated genetically with each other (RhoG = 0.45; P = 0.0012). Alternatively, CCT did not correlate genetically with risk of POAG. Conclusions. All the proposed POAG-related traits have genetic components. However, the significant genetic correlations observed between IOP, VCDR, and POAG itself suggest that they most likely represent true endophenotypes that could aid in the identification of genes underlying POAG susceptibility. CCT did not correlate genetically with disease and is unlikely to be a useful surrogate endophenotype for POAG. PMID:20237253

Charlesworth, Jac; Kramer, Patricia L.; Dyer, Tom; Diego, Victor; Samples, John R.; Craig, Jamie E.; Mackey, David A.; Hewitt, Alex W.; Blangero, John

2010-01-01

6

Evaluation of subjects with a moderate cup to disc ratio using optical coherence tomography and Heidelberg retina tomograph 3: Impact of the disc area  

PubMed Central

Aim: The aim was to evaluate subjects with a moderate cup to disc ratio using optical coherence tomograph (OCT) and Heidelberg retina tomograph (HRT) 3. Settings and Design: We included 80 patients with early glaucoma and 80 nonglaucomatous subjects with moderate cup/disc ratio (range of 0.5–0.8) to this cross-sectional study. Subjects and Methods: We compared results of color-coded algorithms of HRT 3 (Moorfields regression analysis [MRA] and Glaucoma probability score [GPS]) and OCT. All outputs are classified into three categories: Within normal limits (WNLs), borderline and outside normal limits (ONLs). Diagnostic accuracies of algorithms were determined using the highest sensitivity criteria. Results: The sensitivities of global MRA, GPS and OCT were 0.75, 0.925 and 0.725, respectively, in average disc area group and 0.85, 1.0 and 0.425, respectively, in large disc area group. The specificities of global MRA, GPS and OCT were 0.55, 0.15 and 0.85, respectively, in average disc area group and 0.425, 0.025 and 0.80, respectively, in large disc area group. Area under receiver operating characteristic curve (AUROC) of global MRA, GPS and OCT were 0.667, 0.617 and 0.792, respectively, in average disc area group and 0.746, 0.576 and 0.627, respectively, in large disc area group. AUROC of global MRA and OCT combination in the average and large disc area groups were 0.828 and 0.825, respectively. Conclusions: In contrast to GPS and OCT algorithms, diagnostic performance of MRA algorithm increased in large disc area group. Combining MRA and OCT algorithms produced satisfactory diagnostic performance in subjects with an average and large disc area. PMID:25686054

Ula?, Fatih; Do?an, Ümit; Kaymaz, Abdulgani; Çelik, Fatih; Çelebi, Serdal

2015-01-01

7

High-aspect ratio vertical comb-drive actuator with small self-aligned finger gaps  

Microsoft Academic Search

A vertical comb-drive actuator with thin, high-aspect ratio comb fingers and small self-aligned gaps is presented. Key to the actuator design is the self-aligned, offset comb-drive fingers, which are fabricated with small gaps (?2 ?m) using a single lithography step. The offset comb fingers are fabricated using two thick conducting layers separated by a thin dielectric layer. The lower fingers

Edwin T. Carlen; Khee-Hang Heng; S. Bakshi; A. Pareek; C. H. Mastrangelo

2005-01-01

8

Nitrogen removal in intermittently aerated vertical flow constructed wetlands: impact of influent COD/N ratios.  

PubMed

The performance response of eight vertical flow constructed wetlands (VFCWs) to different influent COD/N ratios and intermittent aeration in domestic wastewater treatment was investigated. Almost complete nitrification was obtained by intermittent aeration, which well developed alternate anaerobic and aerobic conditions for nitrification and denitrification. Sufficient carbon source supply resulted from influent COD/N ratio of 10 simultaneously obtained high removals of COD (96%), ammonia nitrogen (99%) and total nitrogen (90%) in intermittently aerated VFCWs. In all non-aerated VFCWs, poor nitrification was observed due to oxygen deficiency whilst high COD/N ratios further led to lower COD and nitrogen removal efficiency. The results suggest that intermittent aeration combined with high influent COD/N ratios could achieve high nitrogen removal in VFCWs. PMID:23831745

Fan, Jinlin; Wang, Wengang; Zhang, Bo; Guo, Yeye; Ngo, Huu Hao; Guo, Wenshan; Zhang, Jian; Wu, Haiming

2013-09-01

9

Experimental research on heat transfer of natural convection in vertical rectangular channels with large aspect ratio  

SciTech Connect

This work presents the experimental research on the steady laminar natural convection heat transfer of air in three vertical thin rectangular channels with different gap clearance. The much higher ratio of width to gap clearance (60-24) and the ratio of length to gap clearance (800-320) make the rectangular channels similar with the coolant flow passage in plate type fuel reactors. The vertical rectangular channels were composed of two stainless steal plates and were heated by electrical heating rods. The wall temperatures were detected with the K-type thermocouples which were inserted into the blind holes drilled in the steal plates. Also the air temperatures at the inlet and outlet of the channel were detected. The wall heat fluxes added to the air flow were calculated by the Fourier heat conduction law. The heat transfer characteristics were analyzed, and the average Nusselt numbers in all the three channels could be well correlated with the Rayleigh number or the modified Rayleigh number in a uniform correlation. Furthermore, the maximum wall temperatures were investigated, which is a key parameter for the fuel's integrity during some accidents. It was found that even the wall heat flux was up to 1500 W/m{sup 2}, the maximum wall temperature was lower than 350 C. All this work is valuable for the plate type reactor's design and safety analysis. (author)

Lu, Qing; Qiu, Suizheng; Su, Guanghui [State Key Laboratory of Multi Phase Flow in Power Engineering, Xi'an JIaotong University, Xi'an, Shaanxi 710049 (China); School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Tian, Wenxi; Ye, Zhonghao [School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

2010-01-15

10

Plasma current ramp-up assisted by outer vertical field coils in a high aspect ratio tokamak  

Microsoft Academic Search

Plasma current ramp-up assisted by outer vertical field coils with non-inductively driven current is studied during the ignition access phase in a high aspect ratio tokamak such as ITER-FEAT class tokamak reactor. In a tokamak without the Ohmic transformer, the pl1asma current ramp-up to 8 MA could be achieved by the vertical field with the heating\\/current drive power of 100

Osamu Mitarai; Ryuji Yoshino; Kenkichi Ushigusa

2002-01-01

11

High Rayleigh number convection in rectangular enclosures with differentially heated vertical walls and aspect ratios between zero and unity  

NASA Technical Reports Server (NTRS)

High Rayleigh number convection in a rectangular cavity with insulated horizontal surfaces and differentially heated vertical walls was analyzed for an arbitrary aspect ratio smaller than or equal to unity. Unlike previous analytical studies, a systematic method of solution based on linearization technique and analytical iteration procedure was developed to obtain approximate closed-form solutions for a wide range of aspect ratios. The predicted velocity and temperature fields are shown to be in excellent agreement with available experimental and numerical data.

Kassemi, Siavash A.

1988-01-01

12

Epitaxial growth of a nanoscale, vertically faceted, one-dimensional, high-aspect ratio grating in III-V materials for integrated photonics  

E-print Network

Epitaxial growth of a nanoscale, vertically faceted, one-dimensional, high-aspect ratio grating-dimensional 1D grating with vertical facets is reported. For a pattern direction along 110 , the kinetics of faceting in selective molecular-beam epitaxy MBE induce 11¯0 -type facets vertical to a GaAs 001 substrate

New Mexico, University of

13

Spectrum and Charge Ratio of Vertical Cosmic Ray Muons up to Momenta of 2.5 TeV/c  

SciTech Connect

The ALEPH detector at LEP has been used to measure the momentum spectrum and charge ratio of vertical cosmic ray muons underground. The sea-level cosmic ray muon spectrum for momenta up to 2.5 TeV/c has been obtained by correcting for the overburden of 320 meter water equivalent (mwe). The results are compared with Monte Carlo models for air shower development in the atmosphere. From the analysis of the spectrum the total flux and the spectral index of the cosmic ray primaries is inferred. The charge ratio suggests a dominantly light composition of cosmic ray primaries with energies up to 10{sup 15} eV.

Schmelling, M.; /Heidelberg, Max Planck Inst.; Hashim, N.O.; /Kenyatta U. Coll.; Grupen, C.; /Siegen U.; Luitz, S.; /SLAC; Maciuc, F.; /Heidelberg, Max Planck Inst.; Mailov, A.; /Siegen U.; Muller, A.-S.; /Karlsruhe, Inst. Technol.; Sander, H.-G.; /Mainz U., Inst. Phys.; Schmeling, S.; /CERN; Tcaciuc, R.; /Siegen U.; Wachsmuth, H.; /CERN; Zuber, K.; /Dresden, Tech. U.

2012-09-14

14

Spectrum and Charge Ratio of Vertical Cosmic Ray Muons up to Momenta of 2.5 TeV/c  

E-print Network

The ALEPH detector at LEP has been used to measure the momentum spectrum and charge ratio of vertical cosmic ray muons underground. The sea-level cosmic ray muon spectrum for momenta up to 2.5 TeV/c has been obtained by correcting for the overburden of 320 meter water equivalent (mwe). The results are compared with Monte Carlo models for air shower development in the atmosphere. From the analysis of the spectrum the total flux and the spectral index of the cosmic ray primaries is inferred. The charge ratio suggests a dominantly light composition of cosmic ray primaries with energies up to 10^15 eV.

CosmoALEPH Collaboration; M. Schmelling; N. O. Hashim; C. Grupen; S. Luitz; F. Maciuc; A. Mailov; A. -S. Müller; H. -G. Sander; S. Schmeling; R. Tcaciuc; H. Wachsmuth; K. Zuber

2011-10-19

15

A new method to measure Bowen ratios using high-resolution vertical dry and wet bulb temperature profiles  

NASA Astrophysics Data System (ADS)

The Bowen ratio surface energy balance method is a relatively simple method to determine the latent heat flux and the actual land surface evaporation. The Bowen ratio method is based on the measurement of air temperature and vapour pressure gradients. If these measurements are performed at only two heights, correctness of data becomes critical. In this paper we present the concept of a new measurement method to estimate the Bowen ratio based on vertical dry and wet bulb temperature profiles with high spatial resolution. A short field experiment with distributed temperature sensing (DTS) in a fibre optic cable with 13 measurement points in the vertical was undertaken. A dry and a wetted section of a fibre optic cable were suspended on a 6 m high tower installed over a sugar beet trial plot near Pietermaritzburg (South Africa). Using the DTS cable as a psychrometer, a near continuous observation of vapour pressure and air temperature at 0.20 m intervals was established. These data allowed the computation of the Bowen ratio with a high spatial and temporal precision. The daytime latent and sensible heat fluxes were estimated by combining the Bowen ratio values from the DTS-based system with independent measurements of net radiation and soil heat flux. The sensible heat flux, which is the relevant term to evaluate, derived from the DTS-based Bowen ratio (BR-DTS) was compared with that derived from co-located eddy covariance (R2 = 0.91), surface layer scintillometer (R2 = 0.81) and surface renewal (R2 = 0.86) systems. By using multiple measurement points instead of two, more confidence in the derived Bowen ratio values is obtained.

Euser, T.; Luxemburg, W. M. J.; Everson, C. S.; Mengistu, M. G.; Clulow, A. D.; Bastiaanssen, W. G. M.

2014-06-01

16

Vertical distributions of (99)Tc and the (99)Tc/(137)Cs activity ratio in the coastal water off Aomori, Japan.  

PubMed

Using a sector-field ICP-MS the vertical distributions of the (99)Tc concentration and (99)Tc/(137)Cs activity ratio were measured in the coastal waters off Aomori Prefecture, Japan, where a spent-nuclear-fuel reprocessing plant has begun test operation. The (99)Tc concentrations in surface water ranged from 1.8 to 2.4 mBq/m(3), no greater than the estimated background level. Relatively high (99)Tc/(137)Cs activity ratios (10-12 × 10(-4)) would be caused by the inflow of the high-(99)Tc/(137)Cs water mass from the Japan Sea. There is no observable contamination from the reprocessing plant in the investigated area. The (99)Tc concentration and the (99)Tc/(137)Cs activity ratio in water column showed gradual decreases with depth. Our results implied that (99)Tc behaves in a more conservative manner than (137)Cs in marine environments. PMID:21555170

Nakanishi, Takahiro; Zheng, Jian; Aono, Tatsuo; Yamada, Masatoshi; Kusakabe, Masashi

2011-08-01

17

Infection by a vertically-transmitted microsporidian parasite is associated with a female-biased sex ratio and survival advantage in the amphipod Gammarus roeseli  

Microsoft Academic Search

SUMMARY Vertically transmitted parasites may have positive, neutral or negative effects on host fitness, and are also predicted to exhibit sex-specific virulence to increase the proportion or fitness of the transmitting sex. We investigated these predictions in a study on the survival and sex ratio of offspring of the amphipod Gammarus roeseli from females infected by the vertically transmitted microsporidia

S. MOTREUILand; T. RIGAUD

2007-01-01

18

Vertical cup/disc ratio in relation to optic disc size: its value in the assessment of the glaucoma suspect  

PubMed Central

AIMS—The vertical cup/disc ratio (CDR) has long been used in the assessment of the glaucoma suspect, though the wide range of CDR values in the normal population limits its use. Cup size is related physiologically to disc size and pathologically to glaucomatous damage. Disc size can be measured at the slit lamp as the vertical disc diameter (DD). The ability of the CDR, in relation to DD, to identify glaucomatous optic discs was investigated.?METHODS—88 normal, 53 early glaucoma, and 59 ocular hypertensive subjects underwent stereoscopic optic disc photography and clinical biometry. Photographs were analysed in a masked fashion by computer assisted planimetry. The relation between vertical cup diameter and DD was explored by linear regression, and expressed in terms of CDR. The upper limit of normal was defined by the 95% prediction intervals of this regression (method 1) and by the upper 97.5 percentile for CDR (method 2). The sensitivity and specificity of CDR to identify an optic disc as glaucomatous was tested with these disc size dependent and disc size independent cut offs in small, medium, and large discs.?RESULTS—The CDR was related to DD by the equation CDR = (?1.31 + (1.194 × DD))/DD. The sensitivity in small, medium, and large discs was 80%, 60%, and 38% respectively for method 1 and 33%, 67%, and 63% respectively for method 2. Specificity was 98.9% (method 1) and 97.7% (method 2).?CONCLUSIONS—The CDR, relative to disc size, is useful clinically, especially to assist in identifying small glaucomatous discs.?? Keywords: cup/disc ratio; glaucoma; imaging PMID:9924296

Garway-Heath, D.; Ruben, S.; Viswanathan, A.; Hitchings, R.

1998-01-01

19

Control of Rayleigh-Taylor instability by vertical vibration in large aspect ratio containers.  

PubMed

We consider a horizontal heavy fluid layer supported by a light, immiscible one in a wide (as compared to depth) container, which is vertically vibrated intending to counterbalance the Rayleigh-Taylor instability of the flat, rigid-body vibrating state. In the simplest case when the density and viscosity of the lighter fluid are small compared to their counterparts in the heavier fluid, we apply a long wave, weakly nonlinear analysis that yields a generalized Cahn-Hilliard equation for the evolution of the fluid interface. This equation shows that the stabilizing effect of vibration is like that of surface tension, and is used to analyze the linear stability of the flat state, the local bifurcation at the instability threshold and some global existence and stability properties concerning the steady states without dry spots. The analysis is extended to two cases of practical interest. Namely, (a) the viscosity of one of the fluids is much smaller than that of the other one, and (b) the densities and viscosities of both fluids are quite close to each other. PMID:11461402

Lapuerta, V; Mancebo, F J; Vega, J M

2001-07-01

20

High-aspect-ratio vertically aligned GaAs nanowires fabricated by anodic etching  

NASA Astrophysics Data System (ADS)

Large-scale self-aligned GaAs nanowire arrays were successfully fabricated by the anodic etching of an n-type GaAs (111)B substrate. Although pore generation occurred randomly at the early stage of anodic etching, homogeneous pore growth with a high pore density was accomplished spontaneously on the entire surface of the substrate by prolonged anodic etching under optimized conditions. The GaAs pore walls gradually dissolved during anodic etching and finally three adjacent pores were interconnected to yield a GaAs nanowire with a diameter of approximately 200 nm, a length of approximately 110 ?m, and a high aspect ratio of over 500. Aggregates of GaAs nanowires exhibited a good electron emission property, a low turn-on electric field (2.5 V ?m?1), and a stable field emission current. The field-emission characteristics were enhanced by increasing the spacing between emission sites through post-chemical etching.

Asoh, Hidetaka; Kotaka, Shunsuke; Ono, Sachiko

2014-12-01

21

Inventory and vertical migration of 90Sr fallout and 137Cs/90Sr ratio in Spanish mainland soils.  

PubMed

In this paper the inventory of (90)Sr in 34 points distributed along the Spanish peninsular territory is presented. Obtained values range between 173 Bq/m(2) and 2047 Bq/m(2). From these data set and those (137)Cs data obtained in a previous work the (137)Cs/(90)Sr activity ratio has been established, laying this value between 0.9 and 3.6. Also the migration depth of both radionuclides has been analysed obtaining for (137)Cs an average value 57% lower than that obtained for (90)Sr. Additionally, this paper presents the results obtained in 11 sampling points in which the activity vertical profile has been measured. These profiles have been analysed to state the behaviour of strontium in soils and after, by using a convective-diffusive model, the parameters of the model which governs the vertical migration of (90)Sr in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) have been evaluated. Mean values obtained are 0.20 cm/year and 3.67 cm(2)/year, respectively. PMID:21820771

Herranz, M; Romero, L M; Idoeta, R; Olondo, C; Valiño, F; Legarda, F

2011-11-01

22

Ratio  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

23

New Approach to Enhance Contrast Ratio at Normal Incidence by Controlling the Retardation of Optical Compensation Film in Vertically Aligned Liquid Crystal Displays  

NASA Astrophysics Data System (ADS)

We found that the light leakage at normal incidence of a vertically aligned liquid crystal display (VA-LCD) in black state is strongly affected by the polarization states of obliquely incident light. Experimental results were explained by a light scattering model of substrates on both sides of a liquid crystal layer. Applying this model, we found that the contrast ratio at normal incidence can be highly enhanced by controlling the retardation value of retardation films. This is a new, effective approach to enhancement of the contrast ratio in LCDs, different from the conventional approach of simply decreasing the depolarization of the scattering media.

Makoto Ishiguro,; Megumi Sekiguchi,; Yukito Saitoh,

2010-03-01

24

Effect of pitch-to-diameter ratio on the natural convection heat transfer of two vertically aligned horizontal cylinders  

Microsoft Academic Search

Natural convection heat transfer experiments were conducted for two parallel horizontal cylinders using various pitch-to-diameter ratios (P\\/D) from 1.02 to 9 for the Prandtl numbers between 2014 and 8334 and Rayleigh numbers between 7.3×107 and 4.5×1010. Based upon analogy concept, mass transfer rate were measured instead of heat transfer rates by measuring the limiting current of the cathodic deposition of

Myeong-Seon Chae; Bum-Jin Chung

2011-01-01

25

Combined raman elastic-backscatter LIDAR for vertical profiling of moisture, aerosol extinction, backscatter, and LIDAR ratio  

Microsoft Academic Search

A combined Raman elastic-backscatter lidar has been developed. A XeCl excimer laser is used as the radiation source. Inelastic Raman backscatter signals are spectrally separated from the elastic signal with a filter or grating polychromator. Raman channels can be chosen to register signals from CO2, O2, N2, and H2O. Algorithms for the calculation of the water-vapor mixing ratio from the

A. Ansmann; M. Riebesell; U. Wandinger; C. Weitkamp; E. Voss; W. Lahmann; W. Michaelis

1992-01-01

26

Horizontal to vertical spectral ratio measurements in Port-au-Prince (Haiti) area damaged by the 2010 Haiti earthquake  

NASA Astrophysics Data System (ADS)

In order to evaluate ground shaking characteristics due to surface soil layers in the urban area of Port-au-Prince, short-period ambient noise observation has been performed approximately in a 500x500m grid. The HVSR method was applied to this set of 36 ambient noise measurement points to determine a distribution map of soil predominant periods. This map reveals a general increasing trend in the period values, from the Miocene conglomerates in the northern and southern parts of the town to the central and western zones formed of Pleistocene and Holocene alluvial deposits respectively, where the shallow geological materials that cover the basement increase in thickness. Shorter predominant periods (less than 0.3 s) were found in mountainous and neighbouring zones, where the thickness of sediments is smaller whereas longer periods (greater than 0.5 s) appear in Holocene alluvial fans, where the thickness of sediments is larger. The shallow shear-wave velocity structure have been estimated by means of inversion of Rayleigh wave dispersion data obtained from vertical-component array records of ambient noise. The measurements were carried out at one open space located in Holocene alluvial deposits, using 3 regular pentagonal arrays with 5, 10 and 20m respectively. Reliable dispersion curves were retrieved for frequencies between 4.0 and 14 Hz, with phase velocity values ranging from 420m/s down to 270 m/s. Finally, the average shear-wave velocity of the upper 30 m (VS30) was inverted for characterization of this geological unit.

Navarro, M.; Enomoto, T.; Benito, B.; Belizaire, D.; Navarro, D.; García-Jerez, A.; Dorfeuille, J.

2013-05-01

27

Estimates of site response based on spectral ratio between horizontal and vertical components of ambient vibrations in the source zone of 2001 Bhuj earthquake  

NASA Astrophysics Data System (ADS)

We investigated the site response characteristics of Kachchh rift basin over the meizoseismal area of the 2001, Mw 7.6, Bhuj (NW India) earthquake using the spectral ratio of the horizontal and vertical components of ambient vibrations. Using the available knowledge on the regional geology of Kachchh and well documented ground responses from the earthquake, we evaluated the H/V curves pattern across sediment filled valleys and uplifted areas generally characterized by weathered sandstones. Although our H/V curves showed a largely fuzzy nature, we found that the hierarchical clustering method was useful for comparing large numbers of response curves and identifying the areas with similar responses. Broad and plateau shaped peaks of a cluster of curves within the valley region suggests the possibility of basin effects within valley. Fundamental resonance frequencies (f0) are found in the narrow range of 0.1-2.3 Hz and their spatial distribution demarcated the uplifted regions from the valleys. In contrary, low H/V peak amplitudes (A0 = 2-4) were observed on the uplifted areas and varying values (2-9) were found within valleys. Compared to the amplification factors, the liquefaction indices (kg) were able to effectively indicate the areas which experienced severe liquefaction. The amplification ranges obtained in the current study were found to be comparable to those obtained from earthquake data for a limited number of seismic stations located on uplifted areas; however the values on the valley region may not reflect their true amplification potential due to basin effects. Our study highlights the practical usefulness as well as limitations of the H/V method to study complex geological settings as Kachchh.

Natarajan, Thulasiraman; Rajendran, Kusala

2015-02-01

28

Modulation of Schottky barrier height in graphene/MoS2/metal vertical heterostructure with large current ON–OFF ratio  

NASA Astrophysics Data System (ADS)

Detail transport properties of graphene/MoS2/metal vertical heterostructure have been investigated. The van der Waals interface between the graphene and MoS2 exhibits Schottky barrier. The application of gate voltage to the graphene layer enables us to modulate the Schottky barrier height; thus gives rise to the control of the current flow across the interface. By analyzing the temperature dependence of the conductance, the modulation of Schottky barrier height ?? has been directly determined. We observed significant MoS2 layer number dependence of ??. Moreover, we demonstrate that the device which shows larger ?? exhibits larger current modulation; this is consistent with the fact that the transport of these devices is dominated by graphene/MoS2 Schottky barrier.

Sata, Yohta; Moriya, Rai; Yamaguchi, Takehiro; Inoue, Yoshihisa; Morikawa, Sei; Yabuki, Naoto; Masubuchi, Satoru; Machida, Tomoki

2015-04-01

29

How vertical disparities assist judgements of distance  

Microsoft Academic Search

The ratio of the vertical sizes of corresponding features in the two eyes' retinal images depends both on the associated object's distance and on its horizontal direction relative to the head (eccentricity). It is known that manipulations of vertical size ratio can affect perceived distance, size, depth and shape. We examined how observers use the vertical size ratio to determine

Eli Brenner; Jeroen B. J. Smeets; Michael S. Landy

2001-01-01

30

Observation of Picometer Vertical Emittance with a Vertical Undulator  

NASA Astrophysics Data System (ADS)

Using a vertical undulator, picometer vertical electron beam emittances have been observed at the Australian Synchrotron storage ring. An APPLE-II type undulator was phased to produce a horizontal magnetic field, which creates a synchrotron radiation field that is very sensitive to the vertical electron beam emittance. The measured ratios of undulator spectral peak heights are evaluated by fitting to simulations of the apparatus. With this apparatus immediately available at most existing electron and positron storage rings, we find this to be an appropriate and novel vertical emittance diagnostic.

Wootton, K. P.; Boland, M. J.; Dowd, R.; Tan, Y.-R. E.; Cowie, B. C. C.; Papaphilippou, Y.; Taylor, G. N.; Rassool, R. P.

2012-11-01

31

THE VERTICAL  

NASA Technical Reports Server (NTRS)

'THE VERTICAL' computer keyboard is designed to address critical factors which contribute to Repetitive Motion Injuries (RMI) (including Carpal Tunnel Syndrome) in association with computer keyboard usage. This keyboard splits the standard QWERTY design into two halves and positions each half 90 degrees from the desk. In order to access a computer correctly. 'THE VERTICAL' requires users to position their bodies in optimal alignment with the keyboard. The orthopaedically neutral forearm position (with hands palms-in and thumbs-up) reduces nerve compression in the forearm. The vertically arranged keypad halves ameliorate onset occurrence of keyboard-associated RMI. By utilizing visually-reference mirrored mylar surfaces adjustable to the user's eye, the user is able to readily reference any key indicia (reversed) just as they would on a conventional keyboard. Transverse adjustability substantially reduces cumulative musculoskeletal discomfort in the shoulders. 'THE VERTICAL' eliminates the need for an exterior mouse by offering a convenient finger-accessible curser control while the hands remain in the vertically neutral position. The potential commercial application for 'THE VERTICAL' is enormous since the product can effect every person who uses a computer anywhere in the world. Employers and their insurance carriers are spending hundreds of millions of dollars per year as a result of RMI. This keyboard will reduce the risk.

Albert, Stephen L.; Spencer, Jeffrey B.

1994-01-01

32

Bedrock topography of western Cape Cod, Massachusetts, based on bedrock altitudes from geologic borings and analysis of ambient seismic noise by the horizontal-to-vertical spectral-ratio method  

USGS Publications Warehouse

This report presents a topographic map of the bedrock surface beneath western Cape Cod, Massachusetts, that was prepared for use in groundwater-flow models of the Sagamore lens of the Cape Cod aquifer. The bedrock surface of western Cape Cod had been characterized previously through seismic refraction surveys and borings drilled to bedrock. The borings were mostly on and near the Massachusetts Military Reservation (MMR). The bedrock surface was first mapped by Oldale (1969), and mapping was updated in 2006 by the Air Force Center for Environmental Excellence (AFCEE, 2006). This report updates the bedrock-surface map with new data points collected by using a passive seismic technique based on the horizontal-to-vertical spectral ratio (HVSR) of ambient seismic noise (Lane and others, 2008) and from borings drilled to bedrock since the 2006 map was prepared. The HVSR method is based on a relationship between the resonance frequency of ambient seismic noise as measured at land surface and the thickness of the unconsolidated sediments that overlie consolidated bedrock. The HVSR method was shown by Lane and others (2008) to be an effective method for determining sediment thickness on Cape Cod owing to the distinct difference in the acoustic impedance between the sediments and the underlying bedrock. The HVSR data for 164 sites were combined with data from 559 borings to bedrock in the study area to create a spatially distributed dataset that was manually contoured to prepare a topographic map of the bedrock surface. The interpreted bedrock surface generally slopes downward to the southeast as was shown on the earlier maps by Oldale (1969) and AFCEE (2006). The surface also has complex small-scale topography characteristic of a glacially eroded surface. More information about the methods used to prepare the map is given in the pamphlet that accompanies this plate.

Fairchild, Gillian M.; Lane, John W.; Voytek, Emily B.; LeBlanc, Denis R.

2013-01-01

33

Vertical constituent transport in the mesosphere  

Microsoft Academic Search

Ground-based microwave spectroscopy measurements of mesospheric CO and H2O vertical mixing ratio profiles are used to infer vertical mixing rates in the upper mesosphere. The CO and H2O data consistently imply vertical eddy diffusion coefficients in the 70- to 85-km region of 100,000-200,000 sq cm\\/s during spring through summer at midlatidues. Although chemical acceleration of vertical transport is substantial for

Darrell F. Strobel; Michael E. Summers; Richard M. Bevilacqua; Matthew T. Deland; Mark Allen

1987-01-01

34

Vertical Farm  

NSDL National Science Digital Library

With the continued growth of the human population of the Earth, there is increasing concern with the planet's ability to provide sustenance for all of its inhabitants. This compelling website by Dickson Despommier and his colleagues at Columbia University provides a worthy alternative to other forms of agriculture: the vertical farm. As Dr. Despommier notes on the site, "..they offer the promise of urban renewal, sustainable production of a safe and varied food supply (year-round crop production), and the eventual repair of ecosystems that have been sacrificed for horizontal farming." The site offers a great deal of information about these vertical farms, a detailed essay on the importance of such farms, a number of potential designs, and a discussion forum. Finally, there are a number of plans that indicate how this type of farm might be effectively created and sustained.

35

Vertical solar louver project  

NASA Astrophysics Data System (ADS)

The thermal network analysis computer program MICROPAS was used to analyze Vertical Solar Louvers and other reference solar designs in eight selected climates. The results have been used to generate a set of correlation coefficients for use in performance predictions by the Solar Load Ratio method. At low mass VSL were shown to be superior to ordinary direct gain and equal to the trombe wall systems in energy savings. The energy savings advantage of VSL over direct gain disappears in comparable systems of high mass. Identical solar water tanks of oval cross section were compared in the water wall and VSL configurations.

Bier, C. J.

1984-09-01

36

Comparison of Different Spectral Domain OCT Scanning Protocols for Diagnosing Preperimetric Glaucoma  

PubMed Central

Purpose. To compare the ability of spectral-domain optical coherence tomography (SDOCT) retinal nerve fiber layer (RNFL), optic nerve head (ONH), and macular measurements to detect preperimetric glaucomatous damage. Methods. The study included 142 eyes from 91 patients suspected of having the disease based on the appearance of the optic disc. All eyes had normal visual fields before the imaging session. Forty-eight eyes with progressive glaucomatous damage were included in the preperimetric glaucoma group. Ninety-four eyes without any evidence of progressive glaucomatous damage and followed untreated for 12.8 ± 3.6 years were used as controls. Areas under the receiver operating characteristic curves (AUC) were calculated to summarize diagnostic accuracies of the parameters. Results. The three RNFL parameters with the largest AUCs were average RNFL thickness (0.89 ± 0.03), inferior hemisphere average thickness (0.87 ± 0.03), and inferior quadrant average thickness (0.85 ± 0.03). The three ONH parameters with the largest AUCs were vertical cup-to-disc ratio (0.74 ± 0.04), rim area (0.72 ± 0.05), and rim volume (0.72 ± 0.05). The three macular parameters with the largest AUCs were GCC average thickness (0.79 ± 0.04), GCC inferior thickness (0.79 ± 0.05), and GCC superior thickness (0.76 ± 0.05). Average RNFL thickness performed better than vertical cup-to-disc ratio (0.89 vs. 0.74; P = 0.007) and GCC average thickness (0.89 vs. 0.79; P = 0.015). Conclusions. SDOCT RNFL measurements performed better than ONH and macular measurements for detecting preperimetric glaucomatous damage in a cohort of glaucoma suspects. (ClinicalTrials.gov number, NCT00221897.) PMID:23532529

Lisboa, Renato; Paranhos, Augusto; Weinreb, Robert N.; Zangwill, Linda M.; Leite, Mauro T.; Medeiros, Felipe A.

2013-01-01

37

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.

38

Bilateral ischemic optic neuropathy after transurethral prostatic resection: a case report  

Microsoft Academic Search

BACKGROUND: Nonarteritic ischemic optic neuropathy affects the anterior portion of the optic nerve and is characterized by sudden, painless visual loss. The affected eye has a relative afferent pupillary defect. The typical funduscopic appearance includes optic disc edema, with associated nerve fiber layer hemorrhage. Risk factors include advanced age, systemic hypertension, nocturnal hypotension, diabetes mellitus, and a small cup-to-disc ratio.

Luis M Sadaba; Alfredo Garcia-Layana; Miguel J Maldonado; Jose M Berian

2006-01-01

39

Combining Spectral Domain Optical Coherence Tomography Structural Parameters for the Diagnosis of Glaucoma With Early Visual Field Loss  

PubMed Central

Purpose. To create a multivariable predictive model for glaucoma with early visual field loss using a combination of spectral-domain optical coherence tomography (SD-OCT) parameters, and to compare the results with single variable models. Methods. Two hundred fifty-three subjects (149 healthy controls and 104 with early glaucoma) underwent optic disc and macular scanning using SD-OCT in one randomly selected eye per subject. Sixteen parameters (rim area, cup-to-disc area ratio, vertical cup-to-disc diameter ratio, average and quadrant RNFL thicknesses, average, minimum, and sectoral ganglion cell inner-plexiform layer [GCIPL] thicknesses) were collected and submitted to an exploratory factor analysis (EFA) followed by logistic regression with the backward elimination variable selection technique. Area under the curve (AUC) of the receiver operating characteristic (ROC), sensitivity, specificity, Akaike's information criterion (AIC), predicted probability, prediction interval length (PIL), and classification rates were used to determine the performances of the univariable and multivariable models. Results. The multivariable model had an AUC of 0.995 with 98.6% sensitivity, 96.0% specificity, and an AIC value of 43.29. Single variable models yielded AUCs of 0.943 to 0.987, sensitivities of 82.6% to 95.7%, specificities of 88.0% to 94.0%, and AICs of 113.16 to 59.64 (smaller is preferred). The EFA logistic regression model correctly classified 91.67% of cases with a median PIL of 0.050 in the validation set. Univariable models correctly classified 80.62% to 90.48% of cases with median PILs 1.9 to 3.0 times larger. Conclusions. The multivariable model was successful in predicting glaucoma with early visual field loss and outperformed univariable models in terms of AUC, AIC, PILs, and classification rates. PMID:24282232

Mwanza, Jean-Claude; Warren, Joshua L.; Budenz, Donald L.

2013-01-01

40

Vertical Map Storage.  

ERIC Educational Resources Information Center

Discusses the superiority of vertical filing of maps in compressor-style vertical units over horizontal filing in drawers, emphasizing such factors as physical protection of the collection, ease of filing and retrieval, and efficient use of space. Disadvantages of vertical filing are also reviewed. (Author/JL)

Perry, Joanne M.

1982-01-01

41

Vertical bounce of two vertically aligned balls  

NASA Astrophysics Data System (ADS)

When a tennis ball rests on top of a basketball and both drop to the floor together, the tennis ball is projected vertically at high speed. A mass-spring model of the impact, as well as air track data, suggest that the tennis ball should be projected at relatively low speed. Measurements of the forces on each ball and the bounce of vertically aligned superballs are used to resolve the discrepancy.

Cross, Rod

2007-11-01

42

Vertical axis wind turbines  

DOEpatents

A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

Krivcov, Vladimir (Miass, RU); Krivospitski, Vladimir (Miass, RU); Maksimov, Vasili (Miass, RU); Halstead, Richard (Rohnert Park, CA); Grahov, Jurij (Miass, RU)

2011-03-08

43

Vertical constituent transport in the mesosphere  

NASA Technical Reports Server (NTRS)

Ground-based microwave spectroscopy measurements of mesospheric CO and H2O vertical mixing ratio profiles are used to infer vertical mixing rates in the upper mesosphere. The CO and H2O data consistently imply vertical eddy diffusion coefficients in the 70- to 85-km region of 100,000-200,000 sq cm/s during spring through summer at midlatidues. Although chemical acceleration of vertical transport is substantial for O and O3, below the mesopause, the divergences of their associated fluxes are modest, with at most a factor of 2 effect on the concentrations of O and O3 for measured variability in gravity wave activity. Comparison of Solar Mesosphere Explorer (SME) O3 data with model results reinforces the conclusions of slow vertical mixing in the upper mesosphere as a consequence of the reduced HO(x) catalytic loss of odd oxygen. The changes in chemical rate constants recommended by Rusch and Eckman (1985), in conjunction with slow vertical mixing, yield good agreement with SME O3 data. The slow vertical mixing deduced in this study is consistent with upper limits obtained from studies of the mesospheric heat budget and could be construed as evidence for an advectively controlled mesosphere. A comparison of the vertical eddy diffusion coefficients for momentum stresses, constituent transport, and heat transport suggests that the eddy Prandtl number must be of order 10.

Strobel, Darrell F.; Summers, Michael E.; Bevilacqua, Richard M.; Deland, Matthew T.; Allen, Mark

1987-01-01

44

Radius Ratio  

NSDL National Science Digital Library

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

45

Natural Convection Heat Transfer of a Rectangular Block within a Vertical Enclosure  

Microsoft Academic Search

A numerical solution of the natural convection heat transfer between two cold and hot isolated vertical plates is presented for different horizontal and vertical location ratios of an enclosure. Results show that: a) flow configurations of cold and hot plates are different; b) the increase of vertical location ratio, toward that corresponding to the enclosure middle value, is considerably diminishing

Xiaohui Zhang; Mo Yang

2009-01-01

46

Offset vertical radar profiling  

USGS Publications Warehouse

Diffraction tomography imaging was applied to VRP data acquired by vertically moving a receiving antenna in a number of wells. This procedure simulated a vertical downhole receiver array. Similarly, a transmitting antenna was sequentially moved along a series of radial lines extending outward from the receiver wells. This provided a sequence of multistatic data sets and, from each data set, a two-dimensional vertical cross-sectional image of spatial variations in wave speed was reconstructed.

Witten, A.; Lane, J.

2003-01-01

47

Retrieval of the aerosol vertical distribution from atmospheric radiance  

Microsoft Academic Search

The feasibility of retrieving aerosol vertical distribution from the ratio of atmospheric radiance in, and out of, the oxygen A-band is investigated. Two typical cases of aerosol vertical profiles are considered, namely an exponential profile (aerosols concentrated near the surface), and a Gaussian profile (aerosols concentrated in altitude). The problem is expressed as a linear inverse problem with a compact

Bruno Pelletier; Robert Frouin; Philippe Dubuisson

2009-01-01

48

Vertical Line Test  

NSDL National Science Digital Library

In this activity, students try to connect given points on a graph in a way that they will pass the vertical line test. If the points can't be made to pass the vertical line test, the student must adjust the points so they will pass the test. This activity allows students to explore the vertical line test for functions. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2011-05-24

49

Micromachined electrostatic vertical actuator  

DOEpatents

A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized in a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion` micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.

Lee, Abraham P. (Walnut Creek, CA); Sommargren, Gary E. (Santa Cruz, CA); McConaghy, Charles F. (Livermore, CA); Krulevitch, Peter A. (Pleasanton, CA)

1999-10-19

50

Aiding Vertical Guidance Understanding  

NASA Technical Reports Server (NTRS)

A two-part study was conducted to evaluate modern flight deck automation and interfaces. In the first part, a survey was performed to validate the existence of automation surprises with current pilots. Results indicated that pilots were often surprised by the behavior of the automation. There were several surprises that were reported more frequently than others. An experimental study was then performed to evaluate (1) the reduction of automation surprises through training specifically for the vertical guidance logic, and (2) a new display that describes the flight guidance in terms of aircraft behaviors instead of control modes. The study was performed in a simulator that was used to run a complete flight with actual airline pilots. Three groups were used to evaluate the guidance display and training. In the training, condition, participants went through a training program for vertical guidance before flying the simulation. In the display condition, participants ran through the same training program and then flew the experimental scenario with the new Guidance-Flight Mode Annunciator (G-FMA). Results showed improved pilot performance when given training specifically for the vertical guidance logic and greater improvements when given the training and the new G-FMA. Using actual behavior of the avionics to design pilot training and FMA is feasible, and when the automated vertical guidance mode of the Flight Management System is engaged, the display of the guidance mode and targets yields improved pilot performance.

Feary, Michael; McCrobie, Daniel; Alkin, Martin; Sherry, Lance; Polson, Peter; Palmer, Everett; McQuinn, Noreen

1998-01-01

51

Vertical Integration and Communication  

Microsoft Academic Search

Among the many possible motives for vertical integration, the one emphasized here is uncertainty in the supply of the upstream good and the consequent need for information by downstream firms. The basic conclusion is that, even when the initial conditions are of the type usually thought of as competitive, the upshot will be a tendency to imperfect competition.

Kenneth J. Arrow

1975-01-01

52

Horizontal and vertical disparity, eye position, and stereoscopic slant perception  

Microsoft Academic Search

The slant of a stereoscopically defined surface cannot be determined solely from horizontal disparities or from derived quantities such as horizontal size ratio (HSR). There are four other signals that, in combination with horizontal disparity, could in principle allow an unambiguous estimate of slant: the vergence and version of the eyes, the vertical size ratio (VSR), and the horizontal gradient

Benjamin T. Backus; Martin S. Banks; Raymond van Ee; James A. Crowell

1999-01-01

53

Assessment of the Optic Disc Morphology Using Spectral-Domain Optical Coherence Tomography and Scanning Laser Ophthalmoscopy  

PubMed Central

Objective. To compare the equivalent optic nerve head (OHN) parameters obtained with confocal scanning laser ophthalmoscopy (HRT3) and spectral-domain optical coherence tomography (OCT) in healthy and glaucoma patients. Methods. One hundred and eighty-two consecutive healthy subjects and 156 patients with open-angle glaucoma were divided into 2 groups according to intraocular pressure and visual field outcomes. All participants underwent imaging of the ONH with the HRT3 and the Cirrus OCT. The ONH parameters and the receiver operating characteristic (ROC) curves were compared between both groups. Results. Mean age did not differ between the normal and glaucoma groups (59.55 ± 9.7 years and 61.05 ± 9.4 years, resp.; P = 0.15). Rim area, average cup-to-disc (C/D) ratio, vertical C/D ratio, and cup volume were different between both instruments (P < 0.001). All equivalent ONH parameters, except disc area, were different between both groups (P < 0.001). The best areas under the ROC curve were observed for vertical C/D ratio (0.980 for OCT and 0.942 for HRT3; P = 0.11). Sensitivities at 95% fixed-specificities of OCT parameters were higher than those of HRT3. Conclusions. Equivalent ONH parameters of Cirrus OCT and HRT3 are different and cannot be used interchangeably. ONH parameters measured with OCT yielded a slightly better diagnostic performance. PMID:25110668

Calvo, Pilar; Ferreras, Antonio; Abadia, Beatriz; Ara, Mirian; Figus, Michele; Pablo, Luis E.; Frezzotti, Paolo

2014-01-01

54

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

E-print Network

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

Chun-Wang Ma; Hui-Ling Wei

2014-09-11

55

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

NASA Astrophysics Data System (ADS)

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

Ma, Chun-Wang; Wei, Hui-Ling

2014-11-01

56

The Golden Ratio  

NSDL National Science Digital Library

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

Illuminations National Council of Mathematics

2009-02-18

57

Vertical Motion Simulator  

NSDL National Science Digital Library

The Vertical Motion Simulator (VMS), at the NASA Ames Research Center, is an advanced flight simulation facility. This Web site provides thorough descriptions of all of the VMS systems. The VMS is a full immersion environment, complete with customizable cockpit, controls, and instrumentation to give the appearance of any aerospace vehicle. One of its most intriguing characteristics is "out-the-window graphics." This allows the pilot to see computer generated imagery of real locations, so virtually everything is identical to the actual flying experience. Even aircraft that are still in the design stage can be simulated on the VMS.

58

'Endurance' Untouched (vertical)  

NASA Technical Reports Server (NTRS)

This navigation camera mosaic, created from images taken by NASA's Mars Exploration Rover Opportunity on sols 115 and 116 (May 21 and 22, 2004) provides a dramatic view of 'Endurance Crater.' The rover engineering team carefully plotted the safest path into the football field-sized crater, eventually easing the rover down the slopes around sol 130 (June 12, 2004). To the upper left of the crater sits the rover's protective heatshield, which sheltered Opportunity as it passed through the martian atmosphere. The 360-degree view is presented in a vertical projection, with geometric and radiometric seam correction.

2004-01-01

59

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

60

Measurement of ultralow vertical emittance using a calibrated vertical undulator  

NASA Astrophysics Data System (ADS)

Very few experimental techniques are useful for the direct observation of ultralow vertical emittance in electron storage rings. In this work, quantitative measurements of ultralow (pm rad) electron beam vertical emittance using a vertical undulator are presented. An undulator radiation model was developed using the measured magnetic field of the APPLE-II type undulator. Using calibrated experimental apparatus, a geometric vertical emittance of ?y=0.9 ±0.3 pm rad has been observed. These measurements could also inform modeling of the angular distribution of undulator radiation at high harmonics, for proposed diffraction-limited storage ring light sources.

Wootton, K. P.; Boland, M. J.; Rassool, R. P.

2014-11-01

61

Liquefied strength ratio from liquefaction flow failure case histories  

Microsoft Academic Search

The shear strength of liquefied soil, su(LIQ), mobilized during a liquefaction flow failure is normalized with re- spect to the vertical effective stress ( ? vo ' ) prior to failure to evaluate the liquefied strength ratio, su(LIQ)\\/? vo ' . Liquefied strength ratios mobilized during 33 cases of liquefaction flow failure are estimated using a procedure developed to directly

Scott M. Olson; Timothy D. Stark

2002-01-01

62

Flow effects in a vertical CVD reactor  

NASA Technical Reports Server (NTRS)

A model is presented to simulate the non-Boussinesq flow in a vertical, two-dimensional, chemical vapor deposition reactor under atmospheric pressure. Temperature-dependent conductivity, mass diffusivity, viscosity models, and reactive species mass transfer to the substrate are incorporated. In the limits of small Mach number and small aspect ratio, asymptotic expressions for the flow, temperature, and species fields are developed. Soret diffusion effects are also investigated. Analytical solutions predict an inverse relationship between temperature field and concentration field due to Soret effects. This finding is consistent with numerical simulations, assisting in the understanding of the complex interactions amongst the flow, thermal, and species fields in a chemically reacting system.

Young, G. W.; Hariharan, S. I.; Carnahan, R.

1992-01-01

63

4. VIEW OF VERTICAL BORING MACHINE. (Bullard) Vertical turning lathe ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VIEW OF VERTICAL BORING MACHINE. (Bullard) Vertical turning lathe (VTL). Machining the fixture for GE Turboshroud. G.S. O'Brien, operator. - Juniata Shops, Machine Shop No. 1, East of Fourth Avenue at Third Street, Altoona, Blair County, PA

64

DISTANCES BETWEEN PAIRS OF VERTICES AND VERTICAL PROFILE IN CONDITIONED  

E-print Network

DISTANCES BETWEEN PAIRS OF VERTICES AND VERTICAL PROFILE IN CONDITIONED GALTON­WATSON TREES LUC DEVROYE AND SVANTE JANSON Abstract. We consider a conditioned Galton­Watson tree and prove an estimate of a randomly labelled conditioned Galton­Watson tree converges in distribution, after suitable normalization

Janson, Svante

65

DISTANCES BETWEEN PAIRS OF VERTICES AND VERTICAL PROFILE IN CONDITIONED  

E-print Network

DISTANCES BETWEEN PAIRS OF VERTICES AND VERTICAL PROFILE IN CONDITIONED GALTON--WATSON TREES LUC DEVROYE AND SVANTE JANSON Abstract. We consider a conditioned Galton--Watson tree and prove an estimate of a randomly labelled conditioned Galton--Watson tree converges in distribution, after suitable normalization

Janson, Svante

66

The measurement of attenuation from vertical seismic profiles  

E-print Network

seismograms made from a sonic log recorded in a nearby well, 30 to 50 percent of the measured field 'attenuation' was found to be intrabed multiple induced effects. The authors stated that the effect measured on the synthetic data may be too large due...), amplitude ratios were determined from downhole and monitor spectra. A synthetic vertical seismic profile (VSP) was made using the sonic log from the well. Amplitude ratios calculated from this synthetic were used to remove interference and intrabed...

Davis, Francis Erwin

1983-01-01

67

Vertically reciprocating auger  

NASA Technical Reports Server (NTRS)

The mathematical model and test results developed for the Vertically Reciprocating Auger (VRA) are summarized. The VRA is a device capable of transporting cuttings that result from below surface drilling. It was developed chiefly for the lunar surface, where conventional fluid flushing while drilling would not be practical. The VRA uses only reciprocating motion and transports material through reflections with the surface above. Particles are reflected forward and land ahead of radially placed fences, which prevent the particles from rolling back down the auger. Three input wave forms are considered to drive the auger. A modified sawtooth wave form was chosen for testing, over a modified square wave or sine wave, due to its simplicity and effectiveness. The three-dimensional mathematical model predicted a sand throughput rate of 0.2667 pounds/stroke, while the actual test setup transported 0.075 pounds/stroke. Based on this result, a correction factor of 0.281 is suggested for a modified sawtooth input.

Etheridge, Mark; Morgan, Scott; Fain, Robert; Pearson, Jonathan; Weldi, Kevin; Woodrough, Stephen B., Jr.

1988-01-01

68

Measuring Growth with Vertical Scales  

ERIC Educational Resources Information Center

A vertical score scale is needed to measure growth across multiple tests in terms of absolute changes in magnitude. Since the warrant for subsequent growth interpretations depends upon the assumption that the scale has interval properties, the validation of a vertical scale would seem to require methods for distinguishing interval scales from…

Briggs, Derek C.

2013-01-01

69

Functions and Vertical Line Test  

NSDL National Science Digital Library

This lesson is designed to introduce students to the vertical line test for functions as well as practice plotting points and drawing simple functions. The lesson provides links to discussions and activities related to the vertical line test and functions as well as suggested ways to integrate them into the lesson.

2011-01-17

70

Latitude and longitude vertical disparity  

PubMed Central

The literature on vertical disparity is complicated by the fact that several different definitions of the term “vertical disparity” are in common use, often without a clear statement about which is intended or a widespread appreciation of the properties of the different definitions. Here, we examine two definitions of retinal vertical disparity: elevation-latitude and elevation-longitude disparity. Near the fixation point, these definitions become equivalent, but in general, they have quite different dependences on object distance and binocular eye posture, which have not previously been spelt out. We present analytical approximations for each type of vertical disparity, valid for more general conditions than previous derivations in the literature: we do not restrict ourselves to objects near the fixation point or near the plane of regard, and we allow for non-zero torsion, cyclovergence and vertical misalignments of the eyes. We use these expressions to derive estimates of the latitude and longitude vertical disparity expected at each point in the visual field, averaged over all natural viewing. Finally, we present analytical expressions showing how binocular eye position – gaze direction, convergence, torsion, cyclovergence, and vertical misalignment – can be derived from the vertical disparity field and its derivatives at the fovea. PMID:20055544

Read, Jenny C. A.; Phillipson, Graeme P.; Glennerster, Andrew

2010-01-01

71

Fast vertical mining using diffsets  

Microsoft Academic Search

A number of vertical mining algorithms have been proposed recently for association mining, which have shown to be very effective and usually outperform horizontal approaches. The main advantage of the vertical format is support for fast frequency counting via intersection operations on transaction ids (tids) and automatic pruning of irrelevant data. The main problem with these approaches is when intermediate

Mohammed Javeed Zaki; Karam Gouda

2003-01-01

72

Vertical Mergers and Market Foreclosure  

Microsoft Academic Search

The model in this paper illustrates three effects of vertical mergers when both stages are oligopolistic and vertically integrated and unintegrated producers coexist. First, the merging firm increases its final good output. Second, the resulting backward shift in the residual demand curve facing unintegrated final good producers lowers their demand for the intermediate good. Third, the merged firm withdraws from

Michael A Salinger

1988-01-01

73

Technologies for scaling vertical transistor DRAM cells to 70 nm  

Microsoft Academic Search

Vertical transistor DRAM cells have been demonstrated as viable in the 110 nm generation. This paper describes the issues associated with scaling these cells to the 70 nm node and demonstrates fixes to all known issues. Scaling to 70 nm is possible through the development of two key enabling technologies, high aspect ratio STI fill and low resistance metal deep

R. Divakaruni; C. Radens; M. Belyansky; M. Chudzik; D.-G. Park; S. Saroop; D. Chidambarrao; M. Weybright; H. Akatsu; L. Economikos; K. Settlemyer; J. Strane; D. Dobuzinsky; N. Edleman; G. Feng; Y. Li; R. Jammy; E. Crabbe; G. Bronner

2003-01-01

74

A vertical microfluidic probe.  

PubMed

Performing localized chemical events on surfaces is critical for numerous applications. We earlier invented the microfluidic probe (MFP), which circumvented the need to process samples in closed microchannels by hydrodynamically confining liquids that performed chemistries on surfaces (Juncker et al. Nat. Mater. 2005, 4, 622-628). Here we present a new and versatile probe, the vertical MFP (vMFP), which operates in the scanning mode while overcoming earlier challenges that limited the practical implementation of the MFP technology. The key component of the vMFP is the head, a microfluidic device (?1 cm(2) in area) consisting of glass and Si and having microfluidic features fabricated in-plane in the Si layer. The base configuration of the head has two micrometer-size channels that inject/aspirate liquids and terminate at the apex which is ?1 mm(2). In scanning mode, the head is oriented vertically with the apex parallel to the surface with typical spacing of 1-30 ?m. Such length scales and using flow rates from nanoliters/second to microliters/second allow chemical events to be performed on surfaces with tens of picoliter quantities of reagents. Before scanning, the head is clipped on a holder for leak-free, low dead volume interface assembly, providing a simple world-to-chip interface. Surfaces are scanned by mounting the holder on a computer-controlled stage having ?0.1 ?m resolution in positioning. We present detailed steps to fabricate vMFP heads having channels with dimensions from 1 ?m × 1 ?m to 50 ?m × 50 ?m for liquid localization over areas of 10-10,000 ?m(2). Additionally, advanced design strategies are described to achieve high yield in fabrication and to support a broad range of applications. These include particulate filters, redundant aperture architectures, inclined flow-paths that service apertures, and multiple channels to enable symmetric flow confinement. We also present a method to characterize flow confinement and estimate the distance between the head and the surface by monitoring the evolution of a solution of fluorescently labeled antibody on an activated glass surface. This flow characterization reveals regimes of operation suitable for different surface topographies. We further integrate the dispensing of immersion liquid to the vMFP head for processing surfaces for extended periods of time (?60 min). The versatility of the vMFP is exemplified by patterning fluorescently labeled proteins, inactivation of cells using sodium hypochlorite, and staining living NIH fibroblasts with Cellomics. These applications are enabled by the compact design of the head, which provides easy access to the surface, simplifies alignment, and enables processing surfaces having dimensions from the micrometer to the centimeter scale and with large topographical variations. We therefore believe that ease-of-operation, reconfigurability, and conservative use of chemicals by the vMFP will lead to its widespread use by microtechnologists and the chemical and biomedical communities. PMID:21476506

Kaigala, G V; Lovchik, R D; Drechsler, U; Delamarche, E

2011-05-01

75

Bicycle Gears- Ratios  

NSDL National Science Digital Library

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

2011-01-01

76

Experimental Study of Natural Convection from Electrically Heated Vertical Cylinders Immersed in Air  

Microsoft Academic Search

An experimental study of laminar steady-state natural convection heat transfer from electrically heated vertical cylinders immersed in air has been undertaken. Three stainless steel (316 SS) test sections of different slenderness ratios were employed. Surface temperature profiles along the vertical cylinders were obtained using miniature thermocouples when the cylinders were heated with different power levels resulting in different total wall

Sad Jarall; Antonio Campo

2005-01-01

77

Ramp and Ratios  

NSDL National Science Digital Library

In this activity students view and analyze images of ramps and steps to see if they conform to the requirements of the Americans with Disabilities Act. Students measure horizontal and vertical distances and compute the percent slope for each image. Image measurements are performed using WebImage, a Web-based, customized version of ImageJ.

78

Export industry structure upgrading and China's vertical specialization  

NASA Astrophysics Data System (ADS)

We computed the ratio of China's vertical specialization with revising method of Hummels et al. (2001). We found that China's export has the traits of processing trade, and Asian countries are the main exporter of intermediate goods to China; there is strong positive relationship between export ratio and ratio of China's vertical specialization, indicates that importing of intermediate goods play an important role in China's industry upgrading, China's comparative advantage of export still lies in low price of labor; even if China's production still locates in low value added stage in international supply chain, but China has began to advance its industry structure, and change the mode of production and trade that rely processing trade too much.

Meng, Yinghua

2011-10-01

79

Vertical axis wind turbine airfoil  

DOEpatents

A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

2012-12-18

80

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

81

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

82

Horizontal Inequity and Vertical Redistribution  

Microsoft Academic Search

Inequality of post-tax income among pre-tax equals is evaluated andaggregated to form a global index of horizontal inequity in the income tax.The vertical action of the tax is captured by its inequality effect on averagebetween groups of pre-tax equals. Putting the two together, horizontalinequity measures loss of vertical performance. The identification problem,which has previously been thought insuperable, is addressed by

Peter J. Lambert; Xavier Ramos

1997-01-01

83

Vertical vibration and shape oscillation of acoustically levitated water drops  

NASA Astrophysics Data System (ADS)

We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B.

2014-09-01

84

Vertical vibration and shape oscillation of acoustically levitated water drops  

SciTech Connect

We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072 (China)

2014-09-08

85

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

86

Progress on relationships between horizontal and vertical dust flux: Mathematical, empirical and risk-based perspectives  

NASA Astrophysics Data System (ADS)

Aeolian processes driving sediment flux and corresponding erosion are inherently 3-dimensional, but are primarily studied either with respect to the horizontal flux component, or to a lesser extent the vertical component. Understanding the relationship between horizontal flux and the vertical component of sediment and dust is critical to predicting fundamental processes such as erosion, and to assessing human and environmental risks associated with contaminated sediment and dust. Multiple mathematical approaches to calculate vertical flux of dust exist but are limited in their ability to predict vertical flux across a wide variety of landscapes and soil conditions. To address these issues, here we explore the relationship between horizontal and vertical fluxes from three perspectives: mathematical, based on existing equations; empirical, based on existing and new data; and risk-based, based on translating the former two into a risk context. Mathematical derivations suggest, depending on the approach, the two components could either be a constant ratio or that the vertical flux could be more dependent on the shear stress and particle size than horizontal flux. Empirical data highlight a wide range of ratios, varying by more than two orders of magnitude, though the ratios can be relatively similar within a given site and set of conditions. Risk-based assessment indicates the vertical flux component is relatively important in dose calculations, and consequently further improvement in mathematical and empirical relationships is needed. Collectively, these three perspectives expand insights on horizontal and vertical sediment fluxes and could aide future risk assessment from dust contaminants.

Whicker, Jeffrey J.; Breshears, David D.; Field, Jason P.

2014-09-01

87

Vertical saccades in dyslexic children.  

PubMed

Vertical saccades have never been studied in dyslexic children. We examined vertical visually guided saccades in fifty-six dyslexic children (mean age: 10.5±2.56 years old) and fifty-six age matched non dyslexic children (mean age: 10.3±1.74 years old). Binocular eye movements were recorded using an infrared video-oculography system (mobileEBT®, e(ye)BRAIN). Dyslexic children showed significantly longer latency than the non dyslexic group, also the occurrence of anticipatory and express saccades was more important in dyslexic than in non dyslexic children. The gain and the mean velocity values were significantly smaller in dyslexic than in non dyslexic children. Finally, the up-down asymmetry reported in normal population for the gain and the velocity of vertical saccades was observed in dyslexic children and interestingly, dyslexic children also reported an up-down asymmetry for the mean latency. Taken together all these findings suggested impairment in cortical areas responsible of vertical saccades performance and also at peripheral level of the extra-ocular oblique muscles; moreover, a visuo-attentionnal bias could explain the up-down asymmetry reported for the vertical saccade triggering. PMID:25151607

Tiadi, Aimé; Seassau, Magali; Bui-Quoc, Emmanuel; Gerard, Christophe-Loïc; Bucci, Maria Pia

2014-11-01

88

Seismic Behaviour of Vertical Mass Isolated Structures  

SciTech Connect

In this paper, the seismic behaviour of vertical mass isolated structures against the earthquake is studied. These structures are assumed to be consisted of two subsystems. Mass subsystem possesses low lateral stiffness but carries the major part of mass of the system. Stiffness subsystem, however, controls the deformation of the mass subsystem and attributes with much higher stiffness. The isolator layer is, therefore, located in between the mass and the stiffness subsystems and assumed to be a viscous damper layer. The analytical model used for this investigation is a dual mass-spring model which is an extended form of the three element Maxwell model. In this study, the ability of mass isolation techniques in reducing earthquake effects on buildings with two approaches, parametric and numerical approaches, is shown. In the parametric approach, by definition an isolation factor for structure and determination the dynamic characteristics of system, the relative optimum value of the isolator damping coefficient is obtained. The results provide an insight on role of relative stiffness and mass ratio of the two subsystems. Finally, in the numerical approach, the spectral responses of these structures due to the earthquake are investigated. The results show a noticeable decrease in earthquake input force to vertical mass isolated structures in comparison with non-isolated structures.

Nekooei, M.; Ziyaeifar, M. [Structural Engineering Research Centre, International Institute of Earthquake Engineering and Seismology (IIEES), P.O. Box 19395-3913, Tehran (Iran, Islamic Republic of)

2008-07-08

89

Flow Regimes in Vertical Pneumatic Conveying  

NASA Astrophysics Data System (ADS)

This paper presents a numerical study of the flow regimes in a vertical pipeline by a combined approach of discrete element model for solid phase and computational fluid dynamics model for gas phase. Two typical cases, i.e. the transports of glass beads when Solid Loading Ratio (SLR) = 0.5˜3.4 and polyethylene pellets when SLR = 7.3-33.0 are considered. The results show that in both cases, the phase diagrams featured with the flow transition between the dense-phase flow and dilute-phase flow can be produced. In the transport of glass beads, only the dispersed flow regime is observed. However, both the slug flow regime and the dispersed flow regime are observed in the transport of polyethylene pellets. These results satisfactorily agree with the experiments.

Kuang, S. B.; Yu, A. B.; Zou, Z. S.

2009-06-01

90

Vertical Solar Louver Project. Final technical report  

SciTech Connect

The thermal network analysis computer program MICROPAS has been used to analyze Vertical Solar Louvers and other reference solar designs in eight selected climates. The results have been used to generate a set of correlation coefficients for use in performance predictions by the Solar Load Ratio method as described in The Passive Solar Design Handbook: Volume Three (1). At low mass VSL were shown to be superior to ordinary direct gain and equal to the trombe wall systems in energy savings. The energy savings advantage of VSL over direct gain disappears in comparable systems of high mass. Identical solar water tanks of oval cross section were compared in the water wall and VSL configurations.

Bier, C.J.

1984-09-15

91

Measurements of vertical bar Vcb vertical bar and vertical bar Vub vertical bar at BaBar  

SciTech Connect

We report results from the BABAR Collaboration on the semileptonic B decays, highlighting the measurements of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix elements Vub and Vcb. We describe the techniques used to obtain the matrix element |Vcb| using the measurement of the inclusive B {yields} Xclv process and a large sample of exclusive B {yields} D*lv decays. The vertical bar Vub vertical bar matrix elements has been measured studying different kinematic variables of the B {yields} Xulv process, and also with the exclusive reconstruction of B {yields} {pi}({rho})lv decays.

Rotondo, M. [Dipartimento di Fisica Galileo Galilei, Via Marzolo 8, Padova 35131 (Italy)

2005-10-12

92

Vertical motion simulator familiarization guide  

NASA Technical Reports Server (NTRS)

The Vertical Motion Simulator Familiarization Guide provides a synoptic description of the Vertical Motion Simulator (VMS) and descriptions of the various simulation components and systems. The intended audience is the community of scientists and engineers who employ the VMS for research and development. The concept of a research simulator system is introduced and the building block nature of the VMS is emphasized. Individual sections describe all the hardware elements in terms of general properties and capabilities. Also included are an example of a typical VMS simulation which graphically illustrates the composition of the system and shows the signal flow among the elements and a glossary of specialized terms, abbreviations, and acronyms.

Danek, George L.

1993-01-01

93

Convection in vertical Bridgman configurations  

NASA Technical Reports Server (NTRS)

We are interested in tracing the convective profiles of vertical Bridgman growth in two configurations, the pure Rayleigh convective mode and the combined Rayleigh-Marangoni mode. In order to do so, we conducted a numerical investigation that involved a finite volume calculation. The governing equations were integrated about a cell volume, using the Gauss Theorem and the volume variables like temperature and velocity were related to the surface variables. In order to solve for the pressure field, we employed the continuity equation and the residuals resulted in a Poisson equation. Results and comments for the Rayleigh and Marangoni problems in a vertical cylinder or Bridgman configuration are given.

Narayanan, Ranga

1991-01-01

94

Simplifying Likelihood Ratios  

PubMed Central

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

McGee, Steven

2002-01-01

95

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

96

Recent Progress with Vertical Transistors  

Microsoft Academic Search

Vertical MOS transistors are a promising approach for channel lengths in the range of 100 to 25nm without the need for extreme fine line lithography. These devices provide high satura­ tion currents due to the short channel length and small lateral size due to the 3D-geometry. The channel is defined by epitaxy which can be grown with very good layer

Lothar Risch; Thomas Aeugle; Wolfgang Rosner

1997-01-01

97

Quantum well vertical cavity laser  

SciTech Connect

This patent describes an apparatus which comprises: quantum well laser vertical cavity structure for lasing in a direction non-parallel to the major dimensions of a quantum well, such laser consisting essentially of an active element containing one or two quantum wells and a cavity dependent upon reflectance as between two distributed feedback mirrors.

Huang, R.F.; Jewell, J.L.; McCall, S.L. Jr.; Tai, K.

1991-03-12

98

Vertical two chamber reaction furnace  

Microsoft Academic Search

A vertical two chamber reaction furnace is disclosed. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the

Blaugher

1999-01-01

99

Vertical two chamber reaction furnace  

Microsoft Academic Search

A vertical two chamber reaction furnace. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber.

Blaugher; Richard D

1999-01-01

100

Equilibrium structures in vertical oligopoly  

Microsoft Academic Search

The central purpose of this paper is to examine vertical integration as an equilibrium phenomenon. We model it as integration between Cournot oligopolists in both the upstream and the downstream stages. We consider the issue of private profitability versus collective profitability and show that under several situations the equilibrium outcomes may result in a Prisoner's dilemma. The analysis is extended

Masahiro Abiru; Babu Nahata; Subhashis Raychaudhuri; Michael Waterson

1998-01-01

101

Natural Convection Heat Transfer from Vertical Helical Coils in Oil  

Microsoft Academic Search

An experimental study has been conducted on steady-state natural convection heat transfer from vertical helical coil tubes in heat transfer oil of a Prandtl number range of 250–400. Fifteen coils are used in this experiment. These coils are classified into five groups; each group has a specified coil diameter-to-tube diameter ratio for two, five, and ten turns. The helix coil

Mohamed E. Ali

2006-01-01

102

Natural convection in vertical annuli: A numerical study for constant heat flux on the inner wall  

Microsoft Academic Search

A numerical investigation has been conducted to evaluate the effects of diameter ratio and aspect ratio in natural convection of gases within vertical annuli. The inner cylinder is maintained at uniform heat flux and the outer cylinder at constant temperature. The horizontal top and bottom walls are insulated. Detailed result of ⤠15, 1 ⤠A ⤠10, and 100

J. A. Khan; R. Kumar

1989-01-01

103

Vertical leakage and vertically averaged vertical conductance for Karst Lakes in Florida  

Microsoft Academic Search

In the karst lake district in peninsular Florida in the southeastern United States, as many as 70% of the lakes lack surface outlets, and groundwater outflow is an important part of the water budgets of these lakes. For 11 karst lakes in the Central Lake District, vertical leakage from the lakes to the upper Floridan aquifer averages 0.12 to 4.27

L. H. Motz

1998-01-01

104

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

105

Vertically Integrated Circuits at Fermilab  

SciTech Connect

The exploration of the vertically integrated circuits, also commonly known as 3D-IC technology, for applications in radiation detection started at Fermilab in 2006. This paper examines the opportunities that vertical integration offers by looking at various 3D designs that have been completed by Fermilab. The emphasis is on opportunities that are presented by through silicon vias (TSV), wafer and circuit thinning and finally fusion bonding techniques to replace conventional bump bonding. Early work by Fermilab has led to an international consortium for the development of 3D-IC circuits for High Energy Physics. The consortium has submitted over 25 different designs for the Fermilab organized MPW run organized for the first time.

Deptuch, Grzegorz; Demarteau, Marcel; Hoff, James; Lipton, Ronald; Shenai, Alpana; Trimpl, Marcel; Yarema, Raymond; Zimmerman, Tom; /Fermilab

2009-01-01

106

Global Vertical Rates from VLBl  

NASA Technical Reports Server (NTRS)

The analysis of global VLBI observations provides vertical rates for 50 sites with formal errors less than 2 mm/yr and median formal error of 0.4 mm/yr. These sites are largely in Europe and North America with a few others in east Asia, Australia, South America and South Africa. The time interval of observations is up to 20 years. The error of the velocity reference frame is less than 0.5 mm/yr, but results from several sites with observations from more than one antenna suggest that the estimated vertical rates may have temporal variations or non-geophysical components. Comparisons with GPS rates and corresponding site position time series will be discussed.

Ma, Chopo; MacMillan, D.; Petrov, L.

2003-01-01

107

Kinematic Fitting of Detached Vertices  

SciTech Connect

The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.

Paul Mattione

2007-05-01

108

NASA-Ames vertical gun  

NASA Technical Reports Server (NTRS)

A national facility, the NASA-Ames vertical gun range (AVGR) has an excellent reputation for revealing fundamental aspects of impact cratering that provide important constraints for planetary processes. The current logistics in accessing the AVGR, some of the past and ongoing experimental programs and their relevance, and the future role of this facility in planetary studies are reviewed. Publications resulting from experiments with the gun (1979 to 1984) are listed as well as the researchers and subjects studied.

Schultz, P. H.

1984-01-01

109

Vertical Structure of the Atmosphere  

NSDL National Science Digital Library

Earth is surrounded by a protective atmosphere, composed of nitrogen, oxygen, and argon, and trace amounts of other gases, that protects Earth's surface from damaging solar radiation and plays a major role in water and energy transport. This interactive feature shows the vertical structure of the atmosphere. Viewers can see the regions of the atmosphere, some of the objects (natural and man-made) found at various altitudes, as well as the variations in air temperature and pressure with altitude.

110

Vertical integration, collusion, and tariffs  

Microsoft Academic Search

This article presents a link between tariff rates and industry structure in a dynamic setting. We examine the role of tariffs\\u000a on final-goods in a firm’s decision to integrate and collude in the presence of competitive imports. It is shown that, under\\u000a some conditions, the upstream firm has an incentive to engage in vertical integration to introduce profitably a wholesale

Pedro Mendi; Rafael Moner-Colonques; José J. Sempere-Monerris

2011-01-01

111

Vertical Height of the Atmosphere  

NSDL National Science Digital Library

This is a lesson about the vertical dimension of the atmosphere and includes four activities. Activity 1 Introduces concepts related to distance, including length and height and units of measurement. Students are asked to make comparisons of distances. In activity 2, students learn about the vertical profile of the atmosphere. They work with a graph and plot the heights of objects and the layers of the atmosphere: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. In activity 3, students learn about other forms of visual displays using satellite imagery. They compare images of the same weather feature, a hurricane, using two different images from MODIS and CALIPSO. One image is looking down on the hurricane from space, the other looks through the hurricane to display a profile of the hurricane. Activity 4 reinforces the concept of the vertical nature of the atmosphere. Students will take a CALIPSO satellite image that shows a profile of the atmosphere and use this information to plot mountains and clouds on their own graph of the atmosphere. The recommended order for the activities is to complete the first two activities on day one, and the second two activities on day two. Each day will require approximately 1 to 1.5 hours.

2012-08-03

112

Vertical silicon nanowire arrays for gas sensing  

E-print Network

The goal of this research was to fabricate and characterize vertically aligned silicon nanowire gas sensors. Silicon nanowires are very attractive for gas sensing applications and vertically aligned silicon nanowires are ...

Zhao, Hangbo

2014-01-01

113

Vertical Integration and Technology: Theory and Evidence  

E-print Network

We study the determinants of vertical integration. We first derive a number of predictions regarding the relationship between technology intensity and vertical integration from a simple incomplete contracts model. Then, ...

Acemoglu, Daron

114

What's My Ratio?  

NSDL National Science Digital Library

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

2010-06-30

115

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

116

Ratios and Proportions  

NSDL National Science Digital Library

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

Douglas Jensen

2005-01-01

117

Vertical Lift - Not Just For Terrestrial Flight  

NASA Technical Reports Server (NTRS)

Autonomous vertical lift vehicles hold considerable potential for supporting planetary science and exploration missions. This paper discusses several technical aspects of vertical lift planetary aerial vehicles in general, and specifically addresses technical challenges and work to date examining notional vertical lift vehicles for Mars, Titan, and Venus exploration.

Young, Larry A

2000-01-01

118

Modernizing Vertical Datums in the United States  

Microsoft Academic Search

The National Geodetic Survey (NGS) defines and maintains the National Spatial Reference System (NSRS). Additionally, NGS has a definitive role in providing direct access to the NSRS. An important aspect of the NSRS is the vertical datum, to which geodetic control of elevations is referred. The current official vertical datum for the United States is the North American Vertical Datum

D. B. Zilkoski; D. A. Smith

2006-01-01

119

Vertically aligned nanostructure scanning probe microscope tips  

DOEpatents

Methods and apparatus are described for cantilever structures that include a vertically aligned nanostructure, especially vertically aligned carbon nanofiber scanning probe microscope tips. An apparatus includes a cantilever structure including a substrate including a cantilever body, that optionally includes a doped layer, and a vertically aligned nanostructure coupled to the cantilever body.

Guillorn, Michael A.; Ilic, Bojan; Melechko, Anatoli V.; Merkulov, Vladimir I.; Lowndes, Douglas H.; Simpson, Michael L.

2006-12-19

120

Vertical Contracts and Mandatory Universal Distribution  

E-print Network

Vertical Contracts and Mandatory Universal Distribution Larry S. Karp Jeffrey M. Perloff July 2012 consumer welfare. Keywords: vertical restrictions, mandatory universal distribution, new product oligopoly or hurts consumers and society. We assume that there is a vertical industry structure, with two types

Kammen, Daniel M.

121

Vertical nanopillars for highly localized fluorescence imaging  

E-print Network

Vertical nanopillars for highly localized fluorescence imaging Chong Xiea,1 , Lindsey Hansonb,1 of observation volume is required. Here, we demonstrate the use of vertically aligned silicon dioxide nanopillars along its vertical surface. This effect creates highly confined illumination volume that selectively

Cui, Yi

122

Vertical partitioning algorithms for database design  

Microsoft Academic Search

This paper addresses the vertical partitioning of a set of logical records or a relation into fragments. The rationale behind vertical partitioning is to produce fragments, groups of attribute columns, that “closely match” the requirements of transactions.Vertical partitioning is applied in three contexts: a database stored on devices of a single type, a database stored in different memory levels, and

Shamkant B. Navathe; Stefano Ceri; Gio Wiederhold; Jinglie Dou

1984-01-01

123

Vertical leakage and vertically averaged vertical conductance for karst lakes in Florida  

Microsoft Academic Search

In the karst lake district in peninsular Florida in the southeastern United States, as many as 70% of the lakes lack surface outlets, and groundwater outflow is an important part of the water budgets of these lakes. For 11 karst lakes in the Central Lake District, vertical leakage from the lakes to the upper Floridan aquifer averages 0.12 to 4.27myr-1.

L. H. Motz

1998-01-01

124

On the vertical distribution of carbon monoxide over Bay of Bengal during winter: Role of water vapour and vertical updrafts  

NASA Astrophysics Data System (ADS)

The differences in the spatial pattern of column carbon monoxide (CO) and in-situ measured near-surface CO over Bay of Bengal (BoB) during winter were examined in the light of vertical distribution of CO as retrieved from MOPITT (Measurements Of Pollution In The Troposphere) on board Terra spacecraft. The column CO showed relatively high values over southern-BoB whereas the near-surface CO showed low mixing ratio indicating the existence of significant amount of CO at higher altitudes. The vertical profiles of CO over the BoB region retrieved from MOPITT exhibit a high altitude peak around ~9 km altitude region. The role of water vapour and convective activity/vertical updrafts in establishing the observed vertical profile of CO was investigated. It is found that CO got uplifted to the higher altitude due to updrafts and water vapour caused depletion of CO at lower altitudes which appeared as an apparent high in CO mixing ratio at higher altitude relative to that over lower altitude. The role of water vapour in the destruction of CO was confirmed by box model simulations. Airmass back-trajectory analysis showed that the long range transport from lower troposphere/boundary layer was also partially responsible for higher mixing ratios at higher altitude. In addition, a comparison of in-situ measured near-surface CO and those retrieved from MOPITT using retrieval algorithm Versions 4 and 5 showed that the points of discrepancy have reduced in the Version 5. Biomass burning and anthropogenic activities taking place over the Myanmar landmass was found to be responsible for the hot spots of near-surface-CO over the northeast-BoB.

Girach, I. A.; Nair, Prabha R.

2014-09-01

125

High-frequency vertical current observations in stratified seas  

NASA Astrophysics Data System (ADS)

Although large-scale tidal and inertial motions dominate the kinetic energy and vertical current shear in shelf seas and ocean, short-scale internal waves at higher frequencies close to the local buoyancy frequency are of some interest for studying internal wave breaking and associated diapycnal mixing. Such waves near the upper limit of the inertio-gravity wave band are thought to have relatively short O (10 2-10 3 m) horizontal scales and to show mainly up- and downward motions, which contrasts with generally low aspect ratio large-scale ocean currents. Here, short-term vertical current ( w) observations using moored acoustic Doppler current profiler (ADCP) are presented from a shelf sea, above a continental slope and from the open ocean. The observed w, with amplitudes between 0.015 and 0.05 m s -1, all span a considerable part of the water column, which is not a small vertical scale O(water depth) or O (100-500 m, the maximum range of observations), with either 0 or ? phase change. This implies that they actually represent internal waves of low vertical modes 1 or 2. Maximum amplitudes are found in layers of largest stratification, some in the main pycnocline bordering the frictional bottom boundary layer, suggesting a tidal source. These 'pycnocline-w' compose a regular train of (solitary) internal waves and linearly decrease to small values near surface and bottom.

van Haren, Hans

2009-05-01

126

Neighbourly polytopes with few vertices  

SciTech Connect

A family of neighbourly polytopes in R{sup 2d} with N=2d+4 vertices is constructed. All polytopes in the family have a planar Gale diagram of a special type, namely, with exactly d+3 black points in convex position. These Gale diagrams are parametrized by 3-trees (trees with a certain additional structure). For all polytopes in the family, the number of faces of dimension m containing a given vertex A depends only on d and m. Bibliography: 7 titles.

Devyatov, Rostislav A [M. V. Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow (Russian Federation)

2011-10-31

127

Vertical-Bloch-Line Memory  

NASA Technical Reports Server (NTRS)

Vertical-Bloch-line memory is developmental very-large-scale integrated-circuit block-access magnetic memory. Stores data in form of localized pairs of twists (VBL pairs) in magnetic field at edge of ferromagnetic domain in each stripe. Presence or absence of VBL pair at bit position denotes one or zero, respectively. Offers advantages of resistance to ionizing radiation, potential areal storage density approximately less than 1 Gb/cm squared, data rates approximately less than 1 Gb/s, and average access times of order of milliseconds. Furthermore, mass, volume, and demand for power less than other magnetic and electronic memories.

Katti, Romney R.; Wu, Jiin-Chuan; Stadler, Henry L.

1993-01-01

128

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.

129

Handy Measuring Ratio  

NSDL National Science Digital Library

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

2012-08-23

130

Double-diffusive natural convection in a vertical porous annulus  

SciTech Connect

Double-diffusive convection in porous media has been extensively investigated in recent years, owing to its relevance in varied applications. Examples include the dispersion of chemical contaminants through water-saturated soil, the migration of moisture through the air contained in fibrous insulation and grain-storage installations, and the exploitation of continental geothermal reservoirs. Here, a numerical study is carried out on double-diffusive natural convection in a vertical annular porous layer whose vertical walls are at constant temperatures and concentrations. The investigation covers the range 10 {le} R{sub T} {le} 500, 1 {le} Le {le} 10, {minus}50 {le} N {le} 50, 1 {le}A {le} 5, 1 {le} {kappa} {le} 10, where R{sub T}, Le, N, A, and {kappa} are the thermal Rayleigh number, Lewis number, buoyancy ratio, aspect ratio, and radius ratio of the enclosure, respectively. The two extreme cases of heat-driven and solute-driven natural convection correlations, valid in the boundary layer regime, are derived to calculate the average Nusselt and Sherwood numbers in terms of the governing parameters of the problem. In order to investigate the effects of the combined thermal and solutal buoyancy forces on the average heat and mass transfer, results have been obtained for a large range of buoyancy ratios N. Streamlines, isotherms, and isosolutes in the system are produced to illustrate the flow structure transition from mass species dominated opposing to thermal dominated and mass species dominated aiding flows, respectively. The thermal Rayleigh and Lewis numbers and the radius ratio are found to influence the buoyancy ratio at which flow transition and flow reversal occurs.

Beji, H.; Bennacer, R.; Duval, R. [Lab. Materiaux et Sciences des Constructions, Neuville sur Oise (France); Vasseur, P. [Univ. of Montreal, Quebec (Canada). Ecole Polytechnique

1999-08-13

131

Vertical Diffusivities of Active and Passive Tracers  

NASA Technical Reports Server (NTRS)

The climate models that include a carbon-cycle need the vertical diffusivity of a passive tracer. Since an expression for the latter is not available, it has been common practice to identify it with that of salt. The identification is questionable since T, S are active, not passive tracers. We present the first derivation of the diffusivity of a passive tracer in terms of Ri (Richardson number) and Rq (density ratio, ratio of salinity over temperature z-gradients). The following results have emerged: (a) The passive tracer diffusivity is an algebraic function of Ri, Rq. (b) In doubly stable regimes (DS, partial derivative of T with respect to z > 0, partial derivative of S with respect to z < 0), the passive scalar diffusivity is nearly the same as that of salt/heat for any values of Rq < 0 and Ri > 0. (c) In DC regimes (diffusive convection, partial derivative of T with respect to z < 0, partial derivative of S with respect to z < 0, Rq > 1), the passive scalar diffusivity is larger than that of salt. At Ri = O(1), it can be more than twice as large. (d) In SF regimes (salt fingers, partial derivative of T with respect to z > 0, partial derivative of S with respect to z > 0, Rq < 1), the passive scalar diffusivity is smaller than that of salt. At Ri = O(1), it can be less than half of it. (e) The passive tracer diffusivity predicted at the location of NATRE (North Atlantic Tracer Release Experiment) is discussed. (f) Perhaps the most relevant conclusion is that the common identification of the tracer diffusivity with that of salt is valid only in DS regimes. In the Southern Ocean, where there is the largest CO2 absorption, the dominant regime is diffusive convection discussed in (c) above.

Canuto, V. M.; Cheng, Y.; Howard, A. M.

2010-01-01

132

Infinitely variable ratio transmission  

SciTech Connect

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

Geppert, E.F.

1989-02-21

133

Ratios For All Occasions  

NSDL National Science Digital Library

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

Terese Herrera

134

Laser tracking for vertical control  

NASA Technical Reports Server (NTRS)

The Global Laser Tracking Network has provided LAGEOS ranging data of high accuracy since the first MERIT campaign in late 1983 and we can now resolve centimeter-level three dimensional positions of participating observatories at monthly intervals. In this analysis, the station height estimates have been considered separately from the horizontal components, and can be determined by the strongest stations with a formal standard error of 2 mm using eight years of continuous observations. The rate of change in the vertical can be resolved to a few mm/year, which is at the expected level of several geophysical effects. In comparing the behavior of the stations to that predicted by recent models of post-glacial rebound, we find no correlation in this very small effect. Particular attention must be applied to data and survey quality control when measuring the vertical component, and the survey observations are critical components of the geodynamic results. Seasonal patterns are observed in the heights of most stations, and the possibility of secular motion at the level of several millimeters per year cannot be excluded. Any such motion must be considered in the interpretation of horizontal inter-site measurements, and can help to identify mechanisms which can cause variations which occur linearly with time, seasonally, or abruptly.

Dunn, Peter; Torrence, Mark; Pavlis, Erricos; Kolenkiewicz, Ron; Smith, David

1993-01-01

135

Vertical array receptions of the Heard Island transmissions  

SciTech Connect

A long, vertical line array was deployed off Monterey, California during the Heard Island Feasibility Test to measure the modal content of the received signals. The array contained 32, equally spaced hydrophones spanning from 345 to 1740-m depth. The multichannel data were recorded through a tether to the R/V POINT SUR. The measurements had very low signal to noise ratios and indicated the cw transmission losses were approximately 140 dB for a source/receiver range of 17 000 km. Modal content was analyzed using (i) the modal extent versus depth, (ii) frequency-vertical wave-number spectra, (iii) modal beamforming and (iv) least squares fitting. All led to the conclusion that the modal population is surprisingly rich. There was strong evidence of population up to at least mode seven in the data.

Baggeroer, A.B.; Sperry, B. (Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)); Lashkari, K. (Monterey Bay Aquarium Research Institute, Monterey, California 93943 (United States)); Chiu, C.; Miller, J.H. (Naval Postgraduate School, Monterey, California 93943 (United States)); Mikhalevsky, P.N. (Science Applications International Corporation, McLean, Virginia 22102 (United States)); von der Heydt, K. (Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543 (United States))

1994-10-01

136

Natural convection between a vertical cylinder and a surrounding array  

SciTech Connect

The generic situation considered is natural convection between a single heated, vertical cylinder and a surrounding array of cooler vertical cylinders in a triangular pattern. The ratio of the test section temperature to the cooling tube temperature was varied up to 2.6 by adjusting the electrical power. The Rayleigh number, based on test section diameter and air properties evaluated at cooling tube temperature, ranged from 2.9 x 10{sup 4} to 4.6 x 10{sup 5}. Results indicate that the convective heat transfer data could be approximated as Nu{sub D} (T{sub ts}/T{sub ct}){sup 0.14} = 0.156 Ra{sub D}{sup 1/3} in the apparent turbulent region for Ra{sub L} > 1.2 x 10{sup 11.}

McEligot, D.M.; O`Brien, J.E.; Stoots, C.M.; Larson, T.K.; Christenson, W.A.; Mecham, D.C.; Lussie, W.G.

1992-09-01

137

Natural convection between a vertical cylinder and a surrounding array  

SciTech Connect

The generic situation considered is natural convection between a single heated, vertical cylinder and a surrounding array of cooler vertical cylinders in a triangular pattern. The ratio of the test section temperature to the cooling tube temperature was varied up to 2.6 by adjusting the electrical power. The Rayleigh number, based on test section diameter and air properties evaluated at cooling tube temperature, ranged from 2.9 x 10{sup 4} to 4.6 x 10{sup 5}. Results indicate that the convective heat transfer data could be approximated as Nu{sub D} (T{sub ts}/T{sub ct}){sup 0.14} = 0.156 Ra{sub D}{sup 1/3} in the apparent turbulent region for Ra{sub L} > 1.2 x 10{sup 11.}

McEligot, D.M.; O'Brien, J.E.; Stoots, C.M.; Larson, T.K.; Christenson, W.A.; Mecham, D.C.; Lussie, W.G.

1992-01-01

138

Turbulent vertical diffusivity in the sub-tropical stratosphere  

NASA Astrophysics Data System (ADS)

Vertical (cross-isentropic) mixing is produced by small-scale turbulent processes which are still poorly understood and paramaterized in numerical models. In this work we provide estimates of local equivalent diffusion in the lower stratosphere by comparing balloon borne high-resolution measurements of chemical tracers with reconstructed mixing ratio from large ensembles of random Lagrangian backward trajectories using European Centre for Medium-range Weather Forecasts analysed winds and a chemistry-transport model (REPROBUS). We focus on a case study in subtropical latitudes using data from HIBISCUS campaign. An upper bound on the vertical diffusivity is found in this case study to be of the order of 0.5 m2 s-1 in the subtropical region, which is larger than the estimates at higher latitudes. The relation between diffusion and dispersion is studied by estimating Lyapunov exponents and studying their variation according to the presence of active dynamical structures.

Pisso, I.; Legras, B.

2008-02-01

139

Turbulent vertical diffusivity in the sub-tropical stratosphere  

NASA Astrophysics Data System (ADS)

Vertical (cross-isentropic) mixing is produced by small-scale turbulent processes which are still poorly understood and parametrized in numerical models. In this work we provide estimates of local equivalent diffusion in the lower stratosphere by comparing balloon borne high-resolution measurements of chemical tracers with reconstructed mixing ratio from large ensembles of random Lagrangian backward trajectories using European Center for Medium-range Weather Forecasts analysed winds and a chemistry-transport model (REPROBUS). We have investigated cases in subtropical latitudes using data from HIBISCUS campaign. Upper bound on the vertical diffusivity is found to be of the order of 0.5 m2 s-1 in the subtropical region, which is larger than the estimates at higher latitudes. The relation between diffusion and dispersion is studied by estimating Lyapunov exponents and studying their variation according to the presence of active dynamical structures.

Pisso, I.; Legras, B.

2007-05-01

140

Covert vertical transmission of feline immunodeficiency virus.  

PubMed

Covert vertical transmission of feline immunodeficiency virus (FIV), the feline counterpart of human immunodeficiency virus type 1 (HIV-1), was identified in kittens born to FIV-infected cats. DNA PCR detected FIV gag and env sequences in tissues from kittens nonviable at birth, and in viable kittens monitored postnatally and necropsied at either 11 weeks or 1 year of age. Although FIV DNA was detected in initial blood samples from all 16 viable kittens, viral DNA became increasingly difficult to detect over time and infectious virus could rarely be demonstrated. Only maternal FIV antibody was detected in kitten plasma during the entire postnatal observation period, and kittens remained healthy, with normal CD4:CD8 T cell ratios at >14 months of age. Thus, mother-to-offspring FIV exposure, occurring in utero and postnatally, can result in covert infection in kittens with virus sequestered and contained in tissue sites. These findings appear directly relevant to suspected transient HIV infections and reports of HIV-specific cellular immune responses in highly exposed seronegative adults and uninfected infants born to HIV-positive women. PMID:12804000

Allison, Robin W; Hoover, Edward A

2003-05-01

141

Classification of particle effective shape ratios in cirrus clouds based on the lidar depolarization ratio.  

PubMed

A shape classification technique for cirrus clouds that could be applied to future spaceborne lidars is presented. A ray-tracing code has been developed to simulate backscattered and depolarized lidar signals from cirrus clouds made of hexagonal-based crystals with various compositions and optical depth, taking into account multiple scattering. This code was used first to study the sensitivity of the linear depolarization rate to cloud optical and microphysical properties, then to classify particle shapes in cirrus clouds based on depolarization ratio measurements. As an example this technique has been applied to lidar measurements from 15 mid-latitude cirrus cloud cases taken in Palaiseau, France. Results show a majority of near-unity shape ratios as well as a strong correlation between shape ratios and temperature: The lowest temperatures lead to high shape ratios. The application of this technique to space-borne measurements would allow a large-scale classification of shape ratios in cirrus clouds, leading to better knowledge of the vertical variability of shapes, their dependence on temperature, and the formation processes of clouds. PMID:12148751

Noel, Vincent; Chepfer, Helene; Ledanois, Guy; Delaval, Arnaud; Flamant, Pierre H

2002-07-20

142

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

143

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

144

Vertical combustor for refuse combustion  

SciTech Connect

A vertical combustor for refuse-particle combustion was analyzed for waste-to-energy recovery. A one-dimensional model was constructed that consisted of fuel particles, inert solid particles, and the gaseous mixture. The gaseous mixture was divided further into six chemical species that are involved in combustion at temperatures below about 2000/sup 0/F. It was concluded that such combustors may be viable in the United States since US refuse contains large amounts of volatile matter. Combustion of the relatively small char, however, may not be cost-effective in the present combustor where the fuel residence time is on the order of 2 s for a combustor height of 20 to 30 ft. A computer solution was designed to optimize a given combustor system. A simplified version of the solution was programmed for a TI-59 programmable hand calculator for field use.

Chung, P.M.

1981-06-01

145

Vertical profiles of the O2/N2 ratio in the stratosphere over Japan and Antarctica  

NASA Astrophysics Data System (ADS)

To examine the spatial and temporal behavior of stratospheric O2, air samples were collected using a cryogenic sampler over Sanriku, Japan and Syowa, Antarctica and analyzed for ?(O2/N2), ?15N of N2 and ?18O of O2. The measured values of all these components decreased gradually with height. The differences in ?(O2/N2), ?15N and ?18O between the middle and lowermost levels of the stratosphere were about 250, 100, and 180 per meg, respectively. The observed stratospheric profiles of ?15N and ?18O were in agreement with those calculated using a steady-state 1-dimensional eddy-diffusion/molecular-diffusion model, which suggests that the upward decrease of stratospheric ?(O2/N2) is caused by a gravitational separation of O2 and N2 molecules. The averaged stratospheric ?(O2/N2) at heights above 20-25 km over Sanriku, corrected for the gravitational separation, was always higher than the upper tropospheric ?(O2/N2) value over Japan, and it decreased secularly. From the past temporal ?(O2/N2) variation deduced from the gravitational separation-corrected stratospheric ?(O2/N2) values and the mean ages of the respective air samples, which corresponds to its secular trend in the troposphere, average terrestrial biospheric and oceanic CO2 uptake for October 1993-September 2001 were estimated to be 1.1 +/- 1.3 and 1.8 +/- 1.3 GtC yr-1, respectively.

Ishidoya, Shigeyuki; Sugawara, Satoshi; Hashida, Gen; Morimoto, Shinji; Aoki, Shuji; Nakazawa, Takakiyo; Yamanouchi, Takashi

2006-07-01

146

Abyssal Atlantic circulation during the Last Glacial Maximum: Constraining the ratio between transport and vertical mixing  

E-print Network

The ocean's role in regulating atmospheric carbon dioxide on glacial-interglacial timescales remains an unresolved issue in paleoclimatology. Reduced mixing between deep water masses may have aided oceanic storage of ...

Ferrari, Raffaele

147

A High Aspect-Ratio Polysilicon Vibrating Ring Gyroscope  

Microsoft Academic Search

Drive and Control This paper presents the fabrication and testing of a high aspect-ratio 80um tall polysilicon ring gyroscope (PRG) fabricated using a new dry-release poly-silicon MEMS technology. This single-wafer technology is capable of producing electrically isolated vertical electrodes as tall as the main body polysilicon structure (50 to 100's urn tall) with various size air-gaps ranging from sub-micron to

Farrokh Ayazi; Hsiao H. Chen; Fatih Kocer; Guohong He; Khalil Najafl

2000-01-01

148

Surface tension profiles in vertical soap films  

E-print Network

Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed introducing deformable elastic objets in the films. The shape adopted by those objects set in the film can be related to the surface tension value at a given vertical position by numerical solving of adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position in the soap film can be reproduced by simple modeling taking into account film thickness measurements.

N. Adami; H. Caps

2013-10-01

149

Surface tension profiles in vertical soap films  

E-print Network

Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed introducing deformable elastic objets in the films. The shape adopted by those objects set in the film can be related to the surface tension value at a given vertical position by numerical solving of adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position in the soap film can be reproduced by simple modeling taking into account film thickness measurements.

Adami, N

2013-01-01

150

Horizontal and Vertical R&D Cooperation  

Microsoft Academic Search

This paper introduces a second, vertically related industry into the usual one-industry oligopoly framework of cooperative R&D investment between firms operating on the same product market. R&D efforts are affected by intra- and inter-industry R&D spillovers. Horizontal and vertical R&D cooperation scenarios are compared to R&D competition. It turns out that vertical R&D cooperation is usually the only stable equilibrium

Joachim Inkmann

2000-01-01

151

Natural convection in an enclosure with a vertical baffle  

NASA Astrophysics Data System (ADS)

A numerical study is made of natural convection in an enclosure with a vertical, finitely conducting baffle. The end-wall is assumed to be either perfectly conducting or adiabatic. Predicted flow and isotherm patterns indicate the existence of strong thermal stratification in the baffle/cold wall region and are in qualitative agreement with reported experimental results. The baffle strongly influences the hot-wall Nusselt number distribution, but has a weaker effect on the cold-wall Nusselt number distribution. The predicted Nusselt numbers show satisfactory agreement with the high Rayleigh number based experimental correlation of Lin and Bejan in a partially divided enclosure of aspect ratio 0.3.

Zimmerman, E.; Acharya, S.

1988-10-01

152

Microplasma illumination enhancement of vertically aligned conducting ultrananocrystalline diamond nanorods  

NASA Astrophysics Data System (ADS)

Vertically aligned conducting ultrananocrystalline diamond (UNCD) nanorods are fabricated using the reactive ion etching method incorporated with nanodiamond particles as mask. High electrical conductivity of 275 ?·cm-1 is obtained for UNCD nanorods. The microplasma cavities using UNCD nanorods as cathode show enhanced plasma illumination characteristics of low threshold field of 0.21 V/?m with plasma current density of 7.06 mA/cm2 at an applied field of 0.35 V/?m. Such superior electrical properties of UNCD nanorods with high aspect ratio potentially make a significant impact on the diamond-based microplasma display technology.

Sankaran, Kamatchi Jothiramalingam; Kunuku, Srinivasu; Lou, Shiu-Cheng; Kurian, Joji; Chen, Huang-Chin; Lee, Chi-Young; Tai, Nyan-Hwa; Leou, Keh-Chyang; Chen, Chulung; Lin, I.-Nan

2012-09-01

153

Automatic generation of vertices for the Schroedinger functional  

E-print Network

We present a multiplication algorithm to recursively construct vertices for the Schroedinger functional in the abelian background field case. The algorithm is suited for automatic perturbative calculations with a variety of actions. As first applications, we derive ratios of the lambda parameters between the lattice scheme (improved gauge actions including six link loops) and the $\\bar{\\rm MS}$ scheme, and one-loop results for the Schroedinger functional coupling with a lattice $T=L \\pm a$, which is motivated by considering staggered fermions.

Shinji Takeda; Ulli Wolff

2007-09-26

154

Inequalities and Monotonicity of the Ratio of the Geometric Means of a Positive Arithmetic Sequence with Unit Difference  

ERIC Educational Resources Information Center

For any nonnegative integer "k" and natural numbers "n" and "m," the equations presented in this paper demonstrate the inequalities obtained on the ratio for the geometric means of a positive arithmetic sequence with unit difference, where alpha epsilon [vertical bar]0,1[vertical bar] is a constant. Using the ideas and methods of Chen (2002),…

Qi, Feng

2003-01-01

155

Morphological Features and Important Parameters of Large Optic Discs for Diagnosing Glaucoma  

PubMed Central

Purpose To compare the optic disc parameters of glaucomatous eyes to those of non-glaucomatous eyes with large discs. Methods We studied 225 consecutive eyes with large optic discs (>2.82 mm2): 91 eyes with glaucoma and 134 eyes without glaucoma. An eye was diagnosed with glaucoma when visual field defects were detected by the Humphrey Field Analyzer. All of the Heidelberg Retina Tomograph II (HRT II) parameters were compared between the non-glaucomatous and glaucomatous eyes. A logistic regression analysis of the HRT II parameters was used to establish a new formula for diagnosing glaucoma, and the sensitivity and specificity of the Moorfields Regression Analysis (MRA) was compared to the findings made by our analyses. Results The mean disc area was 3.44±0.50 mm2 in the non-glaucomatous group and 3.40±0.52 mm2 in the glaucoma group. The cup area, cup volume, cup-to-disc area ratio, linear cup/disc ratio, mean cup depth, and the maximum cup depth were significantly larger in glaucomatous eyes than in the non-glaucomatous eyes. The rim area, rim volume, cup shape measurement, mean retinal nerve fiber layer (RNFL) thickness, and RFNL cross-sectional area were significantly smaller in glaucomatous eyes than in non-glaucomatous eyes. The cup-to-disc area ratio, the height variation contour (HVC), and the RNFL cross-sectional area were important parameters for diagnosing the early stage glaucoma, and the cup-to-disc area ratio and cup volume were useful for diagnosing advanced stage glaucoma in eyes with a large optic disc. The new formula had higher sensitivity and specificity for diagnosing glaucoma than MRA. Conclusions The cup-to-disc area ratio, HVC, RNFL cross-sectional area, and cup volume were important parameters for diagnosing glaucoma in eyes with a large optic disc. The important disc parameters to diagnose glaucoma depend on the stage of glaucoma in patients with large discs. PMID:25798580

Okimoto, Satoshi; Yamashita, Keiko; Shibata, Tetsuo; Kiuchi, Yoshiaki

2015-01-01

156

Transient heat and mass transfer by natural convection from vertical surfaces in porous media  

NASA Astrophysics Data System (ADS)

A study on the transient heat and mass transfer from vertical plates embedded in fluid saturated porous media is conducted. The wall temperature and concentration are power functions of the dimensionless streamwise coordinate. Results for the heat and mass transfer rates are obtained for different values of the Lewis number, the buoyancy ratio, the power-law exponent and the ratio of porosity and heat capacity ratio. The transient local Nusselt number at X = 1 is found to be almost independent of the ratio of porosity and heat capacity ratio, while the transient local Sherwood number at X = 1 tends to increase as the ratio of porosity and heat capacity ratio is increased. Moreover, increasing the power-law exponent increases the transient local Nusselt and Sherwood numbers.

Cheng, Ching-Yang

2000-06-01

157

Rayleigh-Benard Convection in a Vertical Cylinder Heated from Below with a Nonuniform Temperature  

Microsoft Academic Search

Rayleigh-Benard convection in a vertical cylinder heated from below with a uniform bottom wall temperature has been studied extensively. At low aspect ratios, the flow starts as an axisymmetric pattern and gradually becomes non-axisymmetric when the Rayleigh number is increased. For aspect ratios around and greater than unity, the first stable flow pattern is a non-axisymmetric mode at all Rayleigh

Gang Luo; Pratap Vanka

2001-01-01

158

Poisson's ratio and crustal seismology  

Microsoft Academic Search

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

Nikolas I. Christensen

1996-01-01

159

Climatic significance of isotope ratios  

Microsoft Academic Search

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

Gérard J. Martin; Maryvonne L. Martin

2003-01-01

160

ITER physics design guidelines at high aspect ratio  

SciTech Connect

The physics requirements for ITER design are formulated in a set of physics design guidelines. These guidelines, established by the ITER Physics Group during the Conceptual Design Activity (CDA, 1988--90), were based on credible extrapolations of the tokamak physics database as assessed during the CDA, and defined a class of tokamak designs (with plasma current I {approximately}20 MA and aspect ratio A {approximately}2.5--3.5) that meet the ITER objectives. Recent US studies have indicated that there may be significant benefits if the ITER-CDA design point is moved from the low aspect ratio, high current baseline (A = 2.79, I = 22 MA) to a high aspect ratio machine at A {approximately}4, I {approximately}15 MA, especially regarding steady-state, technology-testing performance. To adequately assess the physics and technology testing capability of higher aspect ratio design options, several changes are proposed to the original ITER guidelines to reflect the latest (although limited) developments in physics understanding at higher aspect ratios. The critical issues for higher aspect ratio design options are the uncertainty in scaling of confinement with aspect ratio, the variation of vertical stability with elongation and aspect ratio, plasma shaping requirements, ability to control and maintain plasma current and q-profiles for MHD stability (and volt-second consumption), access for current drive, restrictions on field ripple and divertor plate incident angles, etc. 5 refs., 1 tab.

Uckan, N.A.

1991-01-01

161

Vertical polarization beam splitter using a hybrid long-range surface plasmon polariton waveguide  

NASA Astrophysics Data System (ADS)

A vertical polarization beam splitter using a hybrid long-range surface plasmon polariton (LR-SPP) waveguide is proposed for three-dimensional integration of silicon photonic circuits in a chip. The device is based on a three-port directional coupler that is operated based on mode coupling theory. The hybrid LR-SPP waveguide as the central waveguide in a three-port directional coupler plays a key role in transferring the transverse-magnetic (TM)-polarization mode from the input port to the cross port, which is configured with horizontal and vertical offsets. A 9.7 μm-long vertical polarization splitter with an extinction ratio of 30 dB in the C-band is achieved. The effects of dimensional tolerances are also investigated. The vertical polarization splitter is highly compatible with a complementary metal–oxide–semiconductor (CMOS) fabrication process based on the silicon-on-insulator (SOI) platform.

Kim, Jin Tae; Park, Suntak

2014-01-01

162

Highly flexible electronics from scalable vertical thin film transistors.  

PubMed

Flexible thin-film transistors (TFTs) are of central importance for diverse electronic and particularly macroelectronic applications. The current TFTs using organic or inorganic thin film semiconductors are usually limited by either poor electrical performance or insufficient mechanical flexibility. Here, we report a new design of highly flexible vertical TFTs (VTFTs) with superior electrical performance and mechanical robustness. By using the graphene as a work-function tunable contact for amorphous indium gallium zinc oxide (IGZO) thin film, the vertical current flow across the graphene-IGZO junction can be effectively modulated by an external gate potential to enable VTFTs with a highest on-off ratio exceeding 10(5). The unique vertical transistor architecture can readily enable ultrashort channel devices with very high delivering current and exceptional mechanical flexibility. With large area graphene and IGZO thin film available, our strategy is intrinsically scalable for large scale integration of VTFT arrays and logic circuits, opening up a new pathway to highly flexible macroelectronics. PMID:24502192

Liu, Yuan; Zhou, Hailong; Cheng, Rui; Yu, Woojong; Huang, Yu; Duan, Xiangfeng

2014-03-12

163

Metal-assisted chemical etching for very high aspect ratio grooves in n-type silicon wafers  

NASA Astrophysics Data System (ADS)

Metal-assisted chemical etching (MACE) is an inexpensive, simple method for etching silicon structures, including the etching of high aspect ratio grooves. We improve on the best reported results in this area by etching grooves with aspect ratios of 65 (vertical depths 650?µm) in n-type silicon. The grooves maintain an excellent degree of verticality and show minimal width variation. We elucidate some limiting factors and demonstrate the effect of silicon surface roughness on the groove etching.

Booker, Katherine; Brauers, Maureen; Crisp, Erin; Rahman, Shakir; Weber, Klaus; Stocks, Matthew; Blakers, Andrew

2014-12-01

164

Incipient buoyant thermal convection in a vertical cylindrical annulus  

SciTech Connect

The incipient buoyant thermal convection in a vertical cylindrical annulus when heated from below is examined. The ends are assumed to be free, and the sidewalls perfectly conducting. The temperature needed to initiate fluid motion is expressed nondimensionally in terms of the Rayleigh number. The analytical conflict that arises for annuli of infinite aspects ratios due to insufficient independent boundary conditions is resolved. Calculations for the critical Rayleigh numbers are presented for a variety of geometries, and the corresponding velocity and temperature perturbations are also shown. The number of cells increases as the aspect and radius ratio decrease with a strong bias towards the development of azimuthally varying cells. These changes in cellular behavior are expected based on physical justifications and comparisons with previous studies.

Littlefield, D.L. (US Army Ballistic Research Lab., Aberdeen Proving Ground, MD (USA)); Desai, P.V. (Georgia Inst. of Tech., Atlanta (USA))

1990-11-01

165

Robust multi-scale superpixel classification for optic cup localization.  

PubMed

This paper presents an optimal model integration framework to robustly localize the optic cup in fundus images for glaucoma detection. This work is based on the existing superpixel classification approach and makes two major contributions. First, it addresses the issues of classification performance variations due to repeated random selection of training samples, and offers a better localization solution. Second, multiple superpixel resolutions are integrated and unified for better cup boundary adherence. Compared to the state-of-the-art intra-image learning approach, we demonstrate improvements in optic cup localization accuracy with full cup-to-disc ratio range, while incurring only minor increase in computing cost. PMID:25453464

Tan, Ngan-Meng; Xu, Yanwu; Goh, Wooi Boon; Liu, Jiang

2015-03-01

166

Vertical two chamber reaction furnace  

DOEpatents

A vertical two chamber reaction furnace. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium-copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700.degree. and 800.degree. C.) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800.degree. to 950.degree. C. to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product.

Blaugher, Richard D. (Evergreen, CO)

1999-03-16

167

Vertical two chamber reaction furnace  

DOEpatents

A vertical two chamber reaction furnace is disclosed. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700 and 800 C) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800 to 950 C to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product. 2 figs.

Blaugher, R.D.

1999-03-16

168

A vertical axis cyclogiro type wind-turbine with freely-hinged blades  

NASA Astrophysics Data System (ADS)

A description is given of the design, construction and testing of a prototype vertical axis cycloturbine. The machine has straight vertical blades of symmetrical cross-section. Each blade is hinged, on a vertical axis, near its upper and lower extremities to the ends of radial arms projecting from a central, rotating, tower structure. What is believed to be a unique method is used for the control of blade articulation. The cyclic motion of each blade is derived solely from a combination of the centrifuging action of a mass attached to the blade and the aerodynamic load acting on the blade. Results of open-air tests of the small two-bladed prototype unit resulted in the achievement of a maximum power coefficient of 0.37 at a velocity ratio of 3.6 with a runaway velocity ratio of 5.2. The machine was found to self-start easily.

Bayly, D. A.; Kentfield, J. A. C.

169

6, 45106, 2006 Vertical profiles of  

E-print Network

to complex vertical profiles of various reactive trace gases and makes noc- turnal chemistry altitudeACPD 6, 45­106, 2006 Vertical profiles of the nocturnal chemistry of NOx and O3 S. Wang et al.atmos-chem-phys.org/acpd/6/45/ SRef-ID: 1680-7375/acpd/2006-6-45 European Geosciences Union Atmospheric Chemistry and Physics

Paris-Sud XI, Université de

170

Vertical Integration, Monopoly, and the First Amendment.  

ERIC Educational Resources Information Center

This paper addresses the relationship between the First Amendment, monopoly of transmission media, and vertical integration of transmission and content provision. A survey of some of the incentives a profit-maximizing transmission monopolist may have with respect to content is followed by a discussion of how vertical integration affects those…

Brennan, Timothy J.

171

Sewing string tree vertices with ghosts  

E-print Network

It is shown how to sew string vertices with ghosts at tree level in order to produce new tree vertices using the Group Theoretic approach to String Theory. It is then verified the BRST invariance of the sewn vertex and shown that it has the correct ghost number.

L. Sandoval Jr

2001-04-17

172

Downstream Competition, Foreclosure, and Vertical Integration  

E-print Network

Downstream Competition, Foreclosure, and Vertical Integration Gilles Chemla ¤ July 8, 2002 and Management Strategy 12, 2 (2003) 261-289." #12;Downstream Competition, Forclosure, and Vertical Integration Abstract This paper analyzes the impact of competition among downstream ¯rms on an upstream ¯rm's payo

Paris-Sud XI, Université de

173

A Vertically Resolved Planetary Boundary Layer  

NASA Technical Reports Server (NTRS)

Increase of the vertical resolution of the GLAS Fourth Order General Circulation Model (GCM) near the Earth's surface and installation of a new package of parameterization schemes for subgrid-scale physical processes were sought so that the GLAS Model GCM will predict the resolved vertical structure of the planetary boundary layer (PBL) for all grid points.

Helfand, H. M.

1984-01-01

174

The green building envelope: vertical greening  

Microsoft Academic Search

Planting on roofs and façades is one of the most innovative and fastest developing fields of green technologies with respect to the built environment and horticulture. This thesis is focused on vertical greening of structures and to the multi-scale benefits of vegetation. Vertical green can improve the environment in urban areas and is becoming a key design consideration in modern

M. Ottelé

2011-01-01

175

Lunar and Vertical Distribution of Myctophidae  

Microsoft Academic Search

The Myctophidae are the most numerous of the mesopelagic fishes in all oceans. Daily vertical migrations which connected with nutrition and energy exchange, are charac- teristic feature of the myctophids behavior. Myctophidae in main during the nighttime basic feed. There are two ecological groups of Myctophidae on the type of vertical migrations. (Some scientists select the third intermediate group). Superficial

S. Tsarin

2002-01-01

176

Vertical shaft V-type engine  

Microsoft Academic Search

A vertical crankshaft V-type engine is described which consists of a vertical crankshaft having an upper end, a pair of cylinders arranged horizontally forming a V with respect to each other, and each having a cylinder head; a carburetor operatively connected to the cylinders and mounted in the V defined by the cylinders. An air cleaner is operatively connected to

T. Fujikawa; M. Hirata; S. Tamba

1987-01-01

177

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

PubMed

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

Stinnett, A A; Paltiel, A D

1997-01-01

178

Numerical Simulation of Aerodynamic Noise Radiated form Vertical Axis Wind Turbines  

Microsoft Academic Search

Vertical Axis Wind Turbines (hereafter VAWT) are one of the useful renewable energy systems. They have several advantages in comparison with the conventional, propeller-typed, horizontal axis wind turbines. VAWTs operate independently of the wind direction. Moreover, maximum power coefficient can be obtained at lower tip-speed ratio compared to the conventional wind turbines. Flow induced noise is therefore smaller than that

Akiyoshi Iida; Akisato Mizuno; Keiko Fukudome

179

Analysis of the Chimney Natural Convection in a Vertical Porous Cylinder  

Microsoft Academic Search

The problem of natural convection in a vertical opened porous cylinder, with a constant wall temperature, has been investigated numerically. Two types of flows behavior, with and without fluid recirculation, have been considered. The conditions of getting one or the other flow depends on the filtration Rayleigh number (Ra), the aspect ratio (A), and the Biot number (Bi). The thermal

D. E. Ameziani; K. Bouhadef; R. Bennacer; O. Rahli

2008-01-01

180

An experimental investigation of free convection heat transfer in a vertical cylinder with a hemispherical bottom  

Microsoft Academic Search

Transient natural convection heating of a bounded liquid was investigated. The test fluid was in contact with a wall at uniform temperature. An aluminum tank, a vertical cyclinder with a hemispherical bottom, was externally heated by water circulated through a constant temperature bath. Flow phenomena, made visible by an electrochemical process, were photographed. Tests were conducted at three aspect ratios,

T. S. Hunter II

1974-01-01

181

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

182

Vertical-Cavity Surface-Emitting Lasers  

NASA Astrophysics Data System (ADS)

1. Introduction to VCSELs L. A. Coldren, C. W. Wilmsen and H. Temkin; 2. Fundamental issues in VCSEL design L. A. Coldren and Eric R. Hegblom; 3. Enhancement of spontaneous emission in microcavities E. F. Schubert and N. E. J. Hunt; 4. Epitaxy of vertical-cavity lasers R. P. Schneider Jr and Y. H. Young; 5. Fabrication and performance of vertical-cavity surface-emitting lasers Kent D. Choquette and Kent Geib; 6. Polarization related properties of vertical cavity lasers Dmitri Kuksenkov and Henryk Temkin; 7. Visible light emitting vertical cavity lasers Robert L. Thornton; 8. Long-wavelength vertical-cavity lasers Dubrakovo I. Babic, Joachim Piprek and John E. Bowers; 9. Overview of VCSEL applications Richard C. Williamson; 10. Optical interconnection applications and required characteristics Kenichi Kasahara; 11. VCSEL-based fiber-optic data communications Kenneth Hahn and Kirk Giboney; 12. VCSEL-based smart pixels for free space optoelectronic processing C. W. Wilmsen.

Wilmsen, Carl W.; Temkin, Henryk; Coldren, Larry A.

2002-01-01

183

Origami Multistabilty: From Single Vertices to Metasheets  

E-print Network

We explore the surprisingly rich energy landscape of origami-like folding planar structures. We show that the configuration space of rigid-paneled degree-4 vertices, the simplest building blocks of such systems, consists of at least two distinct branches meeting at the flat state. This suggests that generic vertices are at least bistable, but we find that the nonlinear nature of these branches allows for vertices with as many as five distinct stable states. In vertices with collinear folds and/or symmetry, more branches emerge leading to up to six stable states. Finally, we introduce a procedure to tile arbitrary 4-vertices while preserving their stable states, thus allowing the design and creation of multistable origami metasheets.

Scott Waitukaitis; Rémi Menaut; Bryan Gin-ge Chen; Martin van Hecke

2014-09-09

184

Vertical propagation of lakewide internal waves  

NASA Astrophysics Data System (ADS)

Internal waves with diurnal period dominated velocities measured by an Acoustic Doppler Profiler (ADP) in a small lake (main basin 3000 m by 400 m by 18 m). ADP profiles and an along-lake temperature section indicate that the observed waves, like seiches, had horizontal wavelengths exceeding the metalimnion length. However, unlike non-dissipative seiches, the observed waves propagated vertically, carrying energy to the lakebed where waves were absorbed, rather than being strongly reflected. This absorption is predicted by a standard parameterization of boundary layer dissipation. The absence of upward-propagating energy precludes seiche resonance, limits focusing of waves toward attractors, and suggests that hypolimnion dissipation was limited by the supply of downward-propagating energy. Vertical wavelengths were less than the lake depth. Simplified calculations suggest that vertically-propagating waves, as opposed to vertically standing seiches, are most likely where vertical wavelengths are short, near-bed stratification is strong, and lakes are short and deep.

Henderson, Stephen M.; Deemer, Bridget R.

2012-03-01

185

Lidar ratio and depolarization ratio for cirrus clouds.  

PubMed

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

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

2002-10-20

186

Methods of testing parameterizations: Vertical ocean mixing  

NASA Technical Reports Server (NTRS)

The ocean's velocity field is characterized by an exceptional variety of scales. While the small-scale oceanic turbulence responsible for the vertical mixing in the ocean is of scales a few centimeters and smaller, the oceanic general circulation is characterized by horizontal scales of thousands of kilometers. In oceanic general circulation models that are typically run today, the vertical structure of the ocean is represented by a few tens of discrete grid points. Such models cannot explicitly model the small-scale mixing processes, and must, therefore, find ways to parameterize them in terms of the larger-scale fields. Finding a parameterization that is both reliable and plausible to use in ocean models is not a simple task. Vertical mixing in the ocean is the combined result of many complex processes, and, in fact, mixing is one of the less known and less understood aspects of the oceanic circulation. In present models of the oceanic circulation, the many complex processes responsible for vertical mixing are often parameterized in an oversimplified manner. Yet, finding an adequate parameterization of vertical ocean mixing is crucial to the successful application of ocean models to climate studies. The results of general circulation models for quantities that are of particular interest to climate studies, such as the meridional heat flux carried by the ocean, are quite sensitive to the strength of the vertical mixing. We try to examine the difficulties in choosing an appropriate vertical mixing parameterization, and the methods that are available for validating different parameterizations by comparing model results to oceanographic data. First, some of the physical processes responsible for vertically mixing the ocean are briefly mentioned, and some possible approaches to the parameterization of these processes in oceanographic general circulation models are described in the following section. We then discuss the role of the vertical mixing in the physics of the large-scale ocean circulation, and examine methods of validating mixing parameterizations using large-scale ocean models.

Tziperman, Eli

1992-01-01

187

Negative Poisson's ratio polyethylene foams  

Microsoft Academic Search

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

B. Brandel; R. S. Lakes

2001-01-01

188

Sex ratio dependent dispersal when sex ratios vary between patches  

Microsoft Academic Search

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

Ronald M. Nelson; Jaco M. Greeff

2011-01-01

189

Surface tension profiles in vertical soap films  

NASA Astrophysics Data System (ADS)

Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed by introducing deformable elastic objets in the films. The shape adopted by those objects once set in the film is related to the surface tension value at a given vertical position by numerically solving the adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position is predicted by simple modeling that takes into account the mechanical equilibrium of the films coupled to previous thickness measurements.

Adami, N.; Caps, H.

2015-01-01

190

Surface tension profiles in vertical soap films.  

PubMed

Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed by introducing deformable elastic objets in the films. The shape adopted by those objects once set in the film is related to the surface tension value at a given vertical position by numerically solving the adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position is predicted by simple modeling that takes into account the mechanical equilibrium of the films coupled to previous thickness measurements. PMID:25679708

Adami, N; Caps, H

2015-01-01

191

Air/fuel ratio controller  

SciTech Connect

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

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

1980-12-23

192

Effects of volume averaging on the line spectra of vertical velocity from multiple-Doppler radar observations  

NASA Technical Reports Server (NTRS)

Calculations of the ratio of the true one-dimensional spectrum of vertical velocity and that measured with multiple-Doppler radar beams are presented. It was assumed that the effects of pulse volume averaging and objective analysis routines is replacement of a point measurement with a volume integral. A u and v estimate was assumed to be feasible when orthogonal radars are not available. Also, the target fluid was configured as having an infinite vertical dimension, zero vertical velocity at the top and bottom, and having homogeneous and isotropic turbulence with a Kolmogorov energy spectrum. The ratio obtained indicated that equal resolutions among radars yields a monotonically decreasing, wavenumber-dependent response function. A gain of 0.95 was demonstrated in an experimental situation with 40 levels. Possible errors introduced when using unequal resolution radars were discussed. Finally, it was found that, for some flows, the extent of attenuation depends on the number of vertical levels resolvable by the radars.

Gal-Chen, T.; Wyngaard, J. C.

1982-01-01

193

Vertical transport of ozone and CO during super cyclones in the Bay of Bengal as detected by Tropospheric Emission Spectrometer.  

PubMed

Vertical profiles of carbon monoxide (CO) and ozone retrieved from Tropospheric Emission Spectrometer have been analyzed during two super cyclone systems Mala and Sidr. Super cyclones Mala and Sidr traversed the Bay of Bengal (BOB) region on April 24-29, 2006 and November 12-16, 2007 respectively. The CO and ozone plume is observed as a strong enhancement of these pollutants in the upper troposphere over the BOB, indicating deep convective transport. Longitude-height cross-section of these pollutants shows vertical transport to the upper troposphere. CO mixing ratio ~90 ppb is observed near the 146-mb level during the cyclone Mala and near 316 mb during the cyclone Sidr. Ozone mixing ratio ~60-100 ppb is observed near the 316-mb level during both the cyclones. Analysis of National Centers for Environmental Prediction (NCEP) reanalysis vertical winds (omega) confirms vertical transport in the BOB. PMID:20652426

Fadnavis, S; Beig, G; Buchunde, P; Ghude, Sachin D; Krishnamurti, T N

2011-02-01

194

Observed changes in the vertical profile of stratopheric nitrous oxide at Thule, Greenland, February - March 1992  

NASA Technical Reports Server (NTRS)

Using a ground-based mm-wave spectrometer, we have observed stratospheric N2O over Thule, Greenland (76.3 N, 68.4 W) during late February and March, 1992. Vertical profiles of mixing ratio ranging from 16 to 50 km were recovered from molecular emission spectra. The profiles of early March show an abrupt increase in the lower-stratosphere N2O mixing ratio similar to the spring-to-summer change associated with the break up of the Antarctic polar vortex. This increase is correlated with changes in potential vorticity, air temperature, and ozone mixing ratio.

Emmons, Louisa K.; Reeves, John M.; Shindell, Drew T.; Dezafra, Robert L.

1994-01-01

195

Comparison of Aerosol Classification From Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask  

NASA Technical Reports Server (NTRS)

Knowledge of aerosol composition and vertical distribution is crucial for assessing the impact of aerosols on climate. In addition, aerosol classification is a key input to CALIOP aerosol retrievals, since CALIOP requires an inference of the lidar ratio in order to estimate the effects of aerosol extinction and backscattering. In contrast, the NASA airborne HSRL-1 directly measures both aerosol extinction and backscatter, and therefore the lidar ratio (extinction-to-backscatter ratio). Four aerosol intensive properties from HSRL-1 are combined to infer aerosol type. Aerosol classification results from HSRL-1 are used here to validate the CALIOP aerosol type inferences.

Burton, Sharon P.; Ferrare, Rich A.; Omar, Ali H.; Vaughan, Mark A.; Rogers, Raymond R.; Hostetler, Chris a.; Hair, Johnathan W.; Obland, Michael D.; Butler, Carolyn F.; Cook, Anthony L.; Harper, David B.

2012-01-01

196

Flow instability in a vertical annulus under steady state and transient conditions  

SciTech Connect

Experimental data have been obtained for the occurrence of flow instability in a vertical annulus under steady state and transient down-flow conditions. The results show that the primary factor affecting the onset of flow instability is the Q{sub ratio} parameter (a measure of the void production in a channel). In addition, it is shown that for steady state conditions good agreement exists between the single annulus data and single tube data based upon the same L/D ratio. The results also indicate that under transient operation the Q{sub ratio} can be used as a stability criterion.

Fighetti, C.; Kokolis, S.; Maciuca, C.; Reddy, D.G.; Yang, B.; Carrano, V. (Columbia Univ., New York, NY (United States)); McAssey, E. Jr. (Villanova Univ., PA (United States)); Qureshi, Z. (Westinghouse Savannah River Co., Aiken, SC (United States))

1992-01-01

197

Flow instability in a vertical annulus under steady state and transient conditions  

SciTech Connect

Experimental data have been obtained for the occurrence of flow instability in a vertical annulus under steady state and transient down-flow conditions. The results show that the primary factor affecting the onset of flow instability is the Q{sub ratio} parameter (a measure of the void production in a channel). In addition, it is shown that for steady state conditions good agreement exists between the single annulus data and single tube data based upon the same L/D ratio. The results also indicate that under transient operation the Q{sub ratio} can be used as a stability criterion.

Fighetti, C.; Kokolis, S.; Maciuca, C.; Reddy, D.G.; Yang, B.; Carrano, V. [Columbia Univ., New York, NY (United States); McAssey, E. Jr. [Villanova Univ., PA (United States); Qureshi, Z. [Westinghouse Savannah River Co., Aiken, SC (United States)

1992-05-01

198

Vertically stacked multi-heterostructures of layered materials for logic transistors and complementary inverters  

PubMed Central

The layered materials such as graphene have attracted considerable interest for future electronics. Here we report the vertical integration of multi-heterostructures of layered materials to enable high current density vertical field-effect transistors (VFETs). An n-channel VFET is created by sandwiching few-layer molybdenum disulfide (MoS2) as the semiconducting channel between a monolayer graphene and a metal thin film. The VFETs exhibit a room temperature on-off ratio >103, while at same time deliver a high current density up to 5,000 A/cm2, sufficient for high performance logic applications. This study offers a general strategy for the vertical integration of various layered materials to obtain both p- and n-channel transistors for complementary logic functions. A complementary inverter with larger than unit voltage gain is demonstrated by vertically stacking the layered materials of graphene, Bi2Sr2Co2O8 (p-channel), graphene, MoS2 (n-channel), and metal thin film in sequence. The ability to simultaneously achieve high on-off ratio, high current density, and logic integration in the vertically stacked multi-heterostructures can open up a new dimension for future electronics to enable three-dimensional integration. PMID:23241535

Yu, Woo Jong; Li, Zheng; Zhou, Hailong; Chen, Yu; Wang, Yang; Huang, Yu; Duan, Xiangfeng

2014-01-01

199

FG Width Scalability of the 3-D Vertical FG NAND Using the Sidewall Control Gate (SCG)  

NASA Astrophysics Data System (ADS)

Recently, the 3-D vertical Floating Gate (FG) type NAND cell arrays with the Sidewall Control Gate (SCG), such as ESCG, DC-SF and S-SCG, are receiving attention to overcome the reliability issues of Charge Trap (CT) type device. Using this novel cell structure, highly reliable flash cell operations were successfully implemented without interference effect on the FG type cell. However, the 3-D vertical FG type cell has large cell size by about 60% for the cylindrical FG structure. In this point of view, we intensively investigate the scalability of the FG width of the 3-D vertical FG NAND cells. In case of the planar FG type NAND cell, the FG height cannot be scaled down due to the necessity of obtaining sufficient coupling ratio and high program speed. In contrast, for the 3-D vertical FG NAND with SCG, the FG is formed cylindrically, which is fully covered with surrounded CG, and very high CG coupling ratio can be achieved. As results, the scaling of FG width of the 3-D vertical FG NAND cell with S-SCG can be successfully demonstrated at 10nm regime, which is almost the same as the CT layer of recent BE-SONOS NAND.

Seo, Moon-Sik; Endoh, Tetsuo

200

Determination of the operation range of a vertical two-phase closed thermosyphon  

NASA Astrophysics Data System (ADS)

A comprehensive model, proposed for a vertical two-phase closed thermosyphon (TPCT) by the present authors, is further developed by utilizing the criteria for dryout, flooding and boiling limits to investigate the effects of filling ratio on them together, while the available models can just consider one or two limits of them. A new concept named dryout ratio is proposed, which can be used for predicting dryout limit. The empirical correlation and the empirical value, provided by other researchers, are used for predicting flooding and boiling limit, respectively. The experiments with nitrogen as working fluid are performed, and compared with the calculations. The maximum filling ratio is introduced, beyond which the liquid could be carried to condenser and the heat transfer performance can be deteriorated. And then the closed operation range of a vertical TPCT is finally determined, which has not been reported before. The effects of operating pressure and geometries on the range are also analyzed.

Jiao, B.; Qiu, L. M.; Gan, Z. H.; Zhang, X. B.

2012-06-01

201

Subsurface imaging with reverse vertical seismic profiles  

E-print Network

This thesis presents imaging results from a 3D reverse vertical seismic profile (RVSP) dataset measured at a hydrocarbon bearing pinnacle reef in northern Michigan. The study presented many challenges in seismic data ...

Krasovec, Mary L. (Mary Lee), 1972-

2001-01-01

202

23. INCLINED END POST / VERTICAL / DIAGONAL / PORTAL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. INCLINED END POST / VERTICAL / DIAGONAL / PORTAL BRACING DETAIL. VIEW TO SOUTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

203

30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND LOWER CHORD DETAIL OF DECK TRUSS. VIEW TO NORTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

204

Continuous Growth of Vertically Aligned Carbon Nanotubes  

E-print Network

Vertically aligned carbon nanotubes (VACNTs), sometimes called forests or carpets, are a promising material due to their unique physical and scale-dependent physical properties [1-3]. Continuous production of VACNTs is ...

Guzman de Villoria, R.

205

Vertical Axis Wind Turbine Foundation parameter study  

SciTech Connect

The dynamic failure criterion governing the dimensions of prototype Vertical Axis Wind Turbine Foundations is treated as a variable parameter. The resulting change in foundation dimensions and costs is examined.

Lodde, P.F.

1980-07-01

206

Vertical Glider Robots for Subsea Equipment Delivery  

E-print Network

We have developed an underwater vehicle that offers significant performance improvements over existing sub sea elevators. Our Vertical Glider Robot falls under its own weight to a precise location on the seafloor, employing ...

Reed, Brooks L.

2011-01-01

207

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Vertical plane radiation characteristics, f(θ...Broadcast Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

2012-10-01

208

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Vertical plane radiation characteristics, f(θ...Broadcast Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

2011-10-01

209

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Vertical plane radiation characteristics, f(θ...Broadcast Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

2014-10-01

210

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Vertical plane radiation characteristics, f(θ...Broadcast Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

2010-10-01

211

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Vertical plane radiation characteristics, f(θ...Broadcast Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

2013-10-01

212

Edge disjoint cycles through specified vertices  

Microsoft Academic Search

We give a sufficient condition for a simple graphG to have k pairwise edge-disjoint cycles, each of which contains a prescribed set W of vertices. The condition is that the induced subgraph G(W) be 2k-connected, and that for any two vertices at distance two in G(W), at least one of the two has degree at least |V (G)|\\/2 + 2(k

Luis A. Goddyn; Ladislav Stacho

2005-01-01

213

Property price gradients: the vertical dimension  

Microsoft Academic Search

This is an empirical study on the pricing of two vertical property attributes: floor level and building height. Floor level\\u000a is the vertical location of a unit in a multi-storey building; the extra price paid for a higher floor level is labelled a\\u000a floor-level premium. Previous hedonic price studies unequivocally showed that the floor-level premium is positive, but they\\u000a were

S. K. Wong; K. W. Chau; Y. Yau; A. K. C. Cheung

2011-01-01

214

Progressive Ratio Schedules of Reinforcement  

PubMed Central

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

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

2009-01-01

215

Method and apparatus for determining vertical heat flux of geothermal field  

DOEpatents

A method and apparatus for determining vertical heat flux of a geothermal field, and mapping the entire field, is based upon an elongated heat-flux transducer (10) comprised of a length of tubing (12) of relatively low thermal conductivity with a thermopile (20) inside for measuring the thermal gradient between the ends of the transducer after it has been positioned in a borehole for a period sufficient for the tube to reach thermal equilibrium. The transducer is thermally coupled to the surrounding earth by a fluid annulus, preferably water or mud. A second transducer comprised of a length of tubing of relatively high thermal conductivity is used for a second thermal gradient measurement. The ratio of the first measurement to the second is then used to determine the earth's thermal conductivity, k.sub..infin., from a precalculated graph, and using the value of thermal conductivity thus determined, then determining the vertical earth temperature gradient, b, from predetermined steady state heat balance equations which relate the undisturbed vertical earth temperature distributions at some distance from the borehole and earth thermal conductivity to the temperature gradients in the transducers and their thermal conductivity. The product of the earth's thermal conductivity, k.sub..infin., and the earth's undisturbed vertical temperature gradient, b, then determines the earth's vertical heat flux. The process can be repeated many times for boreholes of a geothermal field to map vertical heat flux.

Poppendiek, Heinz F. (LaJolla, CA)

1982-01-01

216

Effect of vertical motion on current meters  

USGS Publications Warehouse

The effect of vertical motion on the performance of current meters at various stream velocities was evaluated to determine whether accurate discharge measurements can be made from a bobbing boat. Three types of current meters--Ott, Price, and vane types--were tested under conditions simulating a bobbing boat. A known frequency and amplitude of vertical motion were imparted to the current meter, and the related effect on the measured stream velocity was determined. One test of the Price meter was made under actual conditions, using a boat and standard measuring gear. The results of the test under actual conditions verified those obtained by simulating the vertical movements of a boat. The tests show that for stream velocities below 2.5 feet per second the accuracy of all three meters is significantly affected when the meters are subjected to certain conditions of vertical motion that can occur during actual field operations. Both the rate of vertical motion and the frequency of vertical oscillation affect the registration of the meter. The results of these tests, presented in the form of graphs and tables, can be used as a guide to determine whether wind and stream flow are within an acceptable range for a reliable discharge measurement from a boat.

Kallio, Nicholas A.

1966-01-01

217

Vertical distribution of (241)Pu in the southern Baltic Sea sediments.  

PubMed

The vertical distribution of plutonium (241)Pu in marine sediments can assist in determining the deposition history and sedimentation process of analyzed regions. In addition, (241)Pu/(239+240)Pu activity ratio could be used as a sensitive fingerprint for radioactive source identification. The present preliminary studies on vertical distribution of (241)Pu in sediments from four regions of the southern Baltic Sea are presented. The distribution of (241)Pu was not uniform and depended on sediment geomorphology and depth as well as location. The highest concentrations of plutonium were found in the surface layers of all analyzed sediments and originated from the Chernobyl accident. PMID:25455816

Strumi?ska-Parulska, Dagmara I

2014-12-15

218

Genetic Association of SNPs near ATOH7, CARD10, CDKN2B, CDC7 and SIX1/SIX6 with the Endophenotypes of Primary Open Angle Glaucoma in Indian Population  

PubMed Central

Primary open angle glaucoma (POAG) belonging to a group of optic neuropathies, result from interaction between genetic and environmental factors. Study of associations with quantitative traits (QTs) is one of the successful strategies to understand the complex genetics of POAG. The current study attempts to explore the association of variations near/in genes like ATOH7, SIX1/SIX6 complex, CDKN2B, CARD10, and CDC7 with POAG and its QTs including vertical cup to disc ratio (VCDR), central corneal thickness (CCT), intra ocular pressure (IOP), and axial length (AL). Case-control study design was carried out in a sample size of 97 POAG cases and 371 controls from South India. Model-based (additive, recessive, dominant) association of the genotypes and their interaction was carried out between cases and controls using chi-square, linear and logistic regression methods. Nominal significance (P<0.05) was observed for QTs like i) VCDR with SNPs rs1900004 (ATOH7); rs1192415 (CDC7); rs10483727 (SIX1/SIX6), rs9607469 (CARD10); ii) CCT with rs1192415; iii) IOP with rs1900004 and iv) AL with rs1900004 and rs1063192 (CDKN2B). We were able to replicate previously known interactions between ATOH7-SIX6 and SIX6-CDKN2B along with few novel interactions between ATOH7—CDC7 and SIX6 with genes including CARD10 and CDC7. In summary, our results suggest that a probable interaction among the candidate genes for QTs, play a major role in determining the individual’s susceptibility to POAG. PMID:25798827

Asokan, Rashima; N, Viswanathan; George, Ronnie; Lingam, Vijaya

2015-01-01

219

Comparison of diagnostic accuracy of HRT-II and HRT-3 to discriminate glaucomatous and non-glaucomatous eyes  

PubMed Central

Purpose To compare the diagnostic accuracy of the Moorfields Regression Analysis (MRA), parameters, and Glaucoma Probability Score (GPS) from Heidelberg Retinal Tomograph HRT-3 with MRA and parameters from HRT-II in discriminating glaucomatous and healthy eyes in subjects of African (AA) and European ancestry (EA). Design case-control, institutional setting. Methods 78 glaucoma patients (AA=44, EA=34) and 89 age-matched controls (AA=46, EA=33), defined by visual fields and self-reported race were included. Imaging was obtained with HRT-II and data were exported to a computer with the HRT-3 software using the same contour line. Area under Receiver-operating Characteristic [ROC] curves [AUC], sensitivity and specificity were evaluated for whole group, AA and EA separately. Mean disc area was compared between correctly and incorrectly diagnosed eyes by each technique. Results Disc, cup and rim areas from HRT3 were lower than HRT-II (P<0.0001). AUC (sensitivity at 95%-specificity) was 0.85 (54%) for vertical cup-to-disc ratio (VCDR) HRT3, 0.84 (45%) for VCDR HRT-II, and 0.81 (44%) for GPS score at temporal sector. MRA-HRT3 showed greater sensitivity but lower specificity than HRT-II for whole group, AA and EA. GPS classification had lowest specificity. Glaucomatous eyes incorrectly classified by GPS had smaller mean disc area (P=0.0002); controls eyes incorrectly classified had greater mean disc area (P=0.015). Conclusions VCDR from HRT-3 showed higher sensitivity than HRT-II and GPS for the whole group, and AA and EA separately. Sensitivity of MRA improved in HRT-3 with some tradeoff in specificity compared to MRA of HRT-II. GPS yielded erroneous classification associated to optic disc size. PMID:17693382

DeLeón-Ortega, Julio E.; Sakata, Lisandro M.; Monheit, Blythe E.; McGwin, Gerald; Arthur, Stella N.; Girkin, Christopher A.

2014-01-01

220

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

221

WHICH HYDRAULIC MODEL TO USE IN VERTICAL FLOW CONSTRUCTED WETLANDS?  

E-print Network

WHICH HYDRAULIC MODEL TO USE IN VERTICAL FLOW CONSTRUCTED WETLANDS? Ania Morvannoua , Nicolas-equilibrium model, preferential flow path, vertical flow constructed wetlands INTRODUCTION Constructed wetlands (CWs

Paris-Sud XI, Université de

222

Competitive co-existence of vertically and horizontally transmitted parasites  

E-print Network

of vertically transmitted bacteria within the female reproductive organs of many arthropods, especially blood by systemic fungal endophytes that are vertically transmitted through seeds (Schardl, 1996). Theory suggests

Lively, Curt

223

Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Detail, Vertical Cross Bracing-End Detail - Cumberland Covered Bridge, Spanning Mississinewa River, Matthews, Grant County, IN

224

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

225

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

226

Theoretical calculations of the pressure, forces, and moments at supersonic speeds due to various lateral motions acting on thin isolated vertical tails  

NASA Technical Reports Server (NTRS)

Velocity potentials, pressure, distributions, and stability derivatives are derived by use of supersonic linearized theory for families of thin isolated vertical tails performing steady rolling, steady yawing, and constant-lateral-acceleration motions. Vertical-tail families (half-delta and rectangular plan forms) are considered for a broad Mach number range. Also considered are the vertical tail with arbitrary sweepback and taper ratio at Mach numbers for which both the leading edge and trailing edge of the tail are supersonic and the triangular vertical tail with a subsonic leading edge and a supersonic trailing edge. Expressions for potentials, pressures, and stability derivatives are tabulated.

Margolis, Kenneth; Bobbitt, Percy J

1956-01-01

227

Measuring in situ vertical hydraulic conductivity in tidal environments  

NASA Astrophysics Data System (ADS)

The hydraulic conductivity of intertidal sediments plays an important role in quantifying seawater-groundwater interactions. However, its accurate and economical in situ evaluation is difficult since available in situ methods do not apply in intertidal zones due to periodic tidal fluctuations. Here a new apparatus is presented for measuring the sediments' vertical hydraulic conductivity in tidal environments and a simple, finite-difference data analysis method is proposed to estimate this key parameter. The new apparatus is easy to operate, and is able to measure in situ vertical hydraulic conductivity ranging from 10-7 m/s to 10-2 m/s in tidal environments within one hour. A posteriori error of the finite-difference approximation method is estimated to have the same magnitude order as the square of the nondimensionalized observation time interval K?t/(LV) (here ?t is the observation time interval, Rd is the diameter ratio of the falling-head water-container standpipe to the undisturbed in situ sediment sample, K is the vertical hydraulic conductivity, and LV is the sample length), which is usually a very small number. The new apparatus and finite-difference method were verified by numerical simulations and many in situ experiments in several coastal case study sites of Bohai Sea, PR China. The finite-difference method has adequate accuracy in estimating the hydraulic conductivity compared with the traditional least-squares fitting method. The relative error between the estimates by the two methods is less than 9.41% and averages 1.22% for all experiments. The new apparatus and simple finite-difference method are recommended for in situ experiment that have many advantages such as economy, efficiency, reliability, and simplicity.

Wang, Xuejing; Li, Hailong; Yang, Jinzhi; Wan, Li; Wang, Xusheng; Jiang, Xiaowei; Guo, Huaming

2014-08-01

228

Vertical turbulent iron flux sustains the Green Belt along the shelf break in the southeastern Bering Sea  

NASA Astrophysics Data System (ADS)

To evaluate the impact of vertical turbulent iron flux on the summertime biological productivity in the Bering Sea Green Belt (GB), we conducted the concurrent observations of dissolved iron (D-Fe) and turbulence along the shelf break of the southeastern Bering Sea for the first time. We show that the GB can be sustained by iron supply from iron-rich, subsurface thick layer distributed along the southeastern shelf break where the GB is located, via strong turbulent vertical mixing. The flux ratio of D-Fe and nitrate was within the range of the N/Fe uptake ratio by GB phytoplankton, suggesting this flux of nutrients can sustain GB productivity.

Tanaka, T.; Yasuda, I.; Kuma, K.; Nishioka, J.

2012-12-01

229

Improvement of high aspect ratio Si etching by optimized oxygen plasma irradiation inserted DRIE  

Microsoft Academic Search

This paper describes an advanced Si-deep etching process achieving a high aspect ratio with excellent verticality by the improvement of the O2 plasma source condition in the oxygen plasma irradiation inserted deep reactive ion etching (OP-DRIE) process that we have developed. The conventional DRIE process which we call the Bosch process has a trade-off relation between the high aspect ratio

Junji Ohara; Yukihiro Takeuchi; Kazuo Sato

2009-01-01

230

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

231

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

232

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

233

Thermal Impacts of Vertical Greenery Systems  

NASA Astrophysics Data System (ADS)

- Using vertical greenery systems to reduce heat transmission is becoming more common in modern architecture. Vertical greenery systems are divided into two main categories; green facades and living walls. This study aims to examine the thermal performance of vertical greenery systems in hot and humid climates. An experimental procedure was used to measure indoor temperature and humidity. These parameters were also measured for the gap between the vertical greenery systems and wall surfaces. Three boxes were used as small-scale rooms. Two boxes were provided with either a living wall or a green facade and one box did not have any greenery (benchmark). Blue Trumpet Vine was used in the vertical greenery systems. The data were recorded over the course of three sunny days in April 2013. An analyses of the results showed that the living wall and green facade reduced indoor temperature up to 4.0 °C and 3.0 °C, respectively. The living wall and green facade also reduced cavity temperatures by 8.0 °C and 6.5 °C, respectively.

Safikhani, Tabassom; Abdullah, Aminatuzuhariah Megat; Ossen, Dilshan Remaz; Baharvand, Mohammad

2014-12-01

234

Vertical Propagation of Lakewide Internal Waves  

NASA Astrophysics Data System (ADS)

Internal seiches dominate flows in the interior of many lakes. Seiche dissipation generates turbulence, which is responsible for mixing heat, sediments, chemicals, organisms, and pollutants. We present observations of a new type of seiche-like internal wave propagating vertically in a small lake (main basin 3000m by 400m by 18m). Velocity and temperature profiles indicate that the observed waves, like seiches, had horizontal wavelengths exceeding the metalimnion length. However, the vertical propagation of the observed waves contrasts with the vertically-standing behavior of non-dissipative seiches. The observed propagation was predicted by a simple model for dissipation in the bottom boundary layer. The model and data indicate that the waves had small vertical group velocity, leading to a slow supply of energy to the lakebed, which could easily be dissipated rather than being reflected. Similar slow vertical propagation and boundary layer absorption is predicted in other short, deep lakes with strong near-bed stratification. The absence of upward-propagating energy precludes seiche resonance, limits focusing of waves toward attractors, and suggests that hypolimnion dissipation was limited by the supply of downward-propagating energy.

Henderson, Stephen; Harrison, John; Deemer, Bridget

2013-04-01

235

Vertical distribution of methyl bromide over Hyderabad, India  

NASA Astrophysics Data System (ADS)

A vertical distribution profile of methyl bromide (CH3Br), obtained from the samples collected at Hyderabad (17.5°N, 78.6°E) during a balloon flight conducted on 9 April 1990, is presented. Its mixing ratio varies from 8 pptv at 10km to 0.5 pptv at 25km altitude. It shows a sharp decrease above the tropopause. CH3Br is the major source of bromine radicals in the atmosphere in the 13 to 27km height region. Halon 1211 (CF2BrCl) is the second major contributor of Br radicals in the 10 to 25km height region while Halon 1301 (CF3Br) is the major source of these radicals only above 25km. The measured CH3Br profile agrees fairly well with the available results from 1-D and 2-D model computations.

Lal, Shyam; Borchers, R.; Fabian, P.; Patra, P. K.; Subbaraya, B. H.

1994-11-01

236

Control of dynamic stall phenomenon for vertical axis wind turbine  

NASA Astrophysics Data System (ADS)

In the last years the wind turbine with vertical axis (VAWT) began to be more attractive due benefits in exploitation, the power range covering usually the domain 2 kW-20 kW. But, VAWTs suffer from many complicated aerodynamically problems, of which dynamic stall is an inherent phenomenon when they are operating at low values of tip speed ratio (TSR < 4), and this has a significant impact on vibration, noise, and power output of the VAWTs. For this reason, in the present work we perform a computational investigation of a two-dimensional dynamic stall phenomenon around a NACA0012 airfoil in oscillating motion at relative low Reynolds number (˜105). The unsteady flow is investigated numerically using RANS approach with two turbulence models (k-? SST and transition SST). The same analysis was performed to evaluate three flow control methods: two passive and one active.

Frunzulic?, Florin; Dumitrescu, Horia; Dumitrache, Alexandru; Suatean, Bogdan

2013-10-01

237

Jamming of Cylindrical Grains in Featureless Vertical Channels  

NASA Astrophysics Data System (ADS)

We study jamming of low aspect-ratio cylindrical Delrin grains falling through a featureless vertical channel. With a grain height less than the grain diameter, these grains resemble aspirin tablets, poker chips, or coins. Unidisperse grains are allowed to fall under the influence of gravity through a uniform channel of square cross-section where the channel width is greater than the grain size and constant along the length of the channel. Channel widths are chosen so that no combination of grain heights and diameters is equal to the channel width. Collections of grains sometimes form jams, stable structures in which the grains are supported by the channel walls and not by grains or walls beneath them. The probability of a jam occurring and the jam's strength are influenced by the grain dimensions and channel width. We will present experimental measurements of the jamming probability and jam strength and discuss the relationship of these results to other experiments and theories.

Baxter, G. William; Barr, Nicholas; Weible, Seth; Friedl, Nicholas

2013-03-01

238

Photoaligned Vertical Aligned Nematic Mode in Liquid Crystals  

NASA Astrophysics Data System (ADS)

The photoaligned vertical aligned nematic (VAN) mode in liquid crystals (LC) was developed using the photosensitive polyimide (PI) JALC 2021-R2, illuminated by obliquely incident nonpolarized light. It has been found that the combination of PI with water soluble sulfonic azo-dye (SD) yields a perfect electro-optical performance of a liquid crystal in the VAN mode. The polar and the azimuthal anchoring strengths of LC in VAN mode were measured both for rubbed and photoaligned surfaces. Increasing the illumination time results in the exponential growth of the contrast ratio in the VAN LC cell. Analysis of anchoring strength and electrooptic behaviour of the photo-aligned LC cells confirm that the mechanism of photo-alignment in our materials includes not only the photodegradation, but mostly the reorientation of both SD-1 and PI molecules to get the average absorption oscillator almost parallel to the direction of the obliquely incident UV light.

Konovalov, Viktor; Chigrinov, Vladimir; Kwok, Hoi Sing; Takada, Hirokazu; Takatsu, Haruyoshi

2004-01-01

239

The Wake of a Single Vertical Axis Wind Turbine  

NASA Astrophysics Data System (ADS)

Vertical axis wind turbines (VAWTs) pose various advantages over traditional horizontal axis wind turbines (HAWTs), including their smaller size and footprint, quiet operation, and ability to produce power under a greater variety of wind directions and wind speeds. To determine the optimal spacing of an array of VAWTs for maximum power output, an understanding of the fundamental wake structure of a single VAWT is needed. This study is among the first attempts to experimentally visualize the wake of a VAWT using stereo particle image velocimetry (PIV). A scale VAWT is placed inside a wind tunnel and a motor rotates the scale model at a constant rotational speed. Wake data at several Reynolds numbers and tip speed ratios indicate that vortices are shed by each blade of the spinning VAWT, demonstrating significant differences between the wake of a VAWT and a spinning cylinder.

Barsky, Danielle

240

Vertically aligned carbon nanofiber electrode arrays for nucleic acid detection  

NASA Astrophysics Data System (ADS)

We present electrochemical detection of DNA targets that corresponds to Escherichia coli O157:H7 16S rRNA gene using a nanoelectrode array consisting of vertically aligned carbon nanofiber (VACNF) electrodes. Parylene C is used as gap filling 'matrix' material to avoid high temperature processing in electrode construction. This easy to deposit film of several micron heights provides a conformal coating between the high aspect ratio VACNFs with negligible pin-holes. The low background currents show the potential of this approach for ultra-sensitive detection. Consistent and reproducible electrochemical-signals are achieved using a simple electrode preparation. This simple, reliable and low-cost approach is a forward step in developing practical sensors for applications like pathogen detection, early cancer diagnosis and environmental monitoring.

Arumugam, Prabhu U.; Yu, Edmond; Riviere, Roger; Meyyappan, M.

2010-10-01

241

Heat transfer due to film condensation on vertical fluted tubes  

NASA Astrophysics Data System (ADS)

An analysis of film condensation on a vertical fluted tube has been made considering gravitational and surface tension effects over the entire fluted surface, and using surface-oriented coordinates. For the first time surface tension effects are determined, as they should, from the shape of the condensate-vapor interface rather than the shape of the flute. Two-dimensional conduction within the condensate film as well as in the fluted tube is considered. A finite-difference solution of the highly non-linear partial differential equation for the film thickness is coupled with a finite-element solution of the condition problem. The procedure has been tested on a sinusoidal flute with amplitude to pitch ratio approx. 0.2. A linear extrapolation, on a log-log basis, of our results shows good comparison with experimental data.

Garg, V. K.; Marto, P. J.

1984-07-01

242

Rayleigh-Bénard convection with uniform vertical magnetic field  

NASA Astrophysics Data System (ADS)

We present the results of direct numerical simulations of Rayleigh-Bénard convection in the presence of a uniform vertical magnetic field near instability onset. We have done simulations in boxes with square as well as rectangular cross sections in the horizontal plane. We have considered the horizontal aspect ratio ? =Ly/Lx=1 and 2. The onset of the primary and secondary instabilities are strongly suppressed in the presence of the vertical magnetic field for ? =1. The Nusselt number Nu scales with the Rayleigh number Ra close to the primary instability as [{Ra-Rac(Q)}/Rac(Q)]0.91, where Rac(Q) is the threshold for onset of stationary convection at a given value of the Chandrasekhar number Q. Nu also scales with Ra/Q as (Ra/Q)?. The exponent ? varies in the range 0.39???0.57 for Ra/Q?25. The primary instability is stationary as predicted by Chandrasekhar. The secondary instability is temporally periodic for Pr =0.1 but quasiperiodic for Pr =0.025 for moderate values of Q. Convective patterns for higher values of Ra consist of periodic, quasiperiodic, and chaotic wavy rolls above the onset of the secondary instability for ? =1. In addition, stationary as well as time-dependent cross rolls are observed, as Ra is further raised. The ratio ro/Pr is independent of Q for smaller values of Q. The delay in the onset of the oscillatory instability is significantly reduced in a simulation box with ? =2. We also observe inclined stationary rolls for smaller values of Q for ? =2.

Basak, Arnab; Raveendran, Rohit; Kumar, Krishna

2014-09-01

243

Pressure Relations and Vertical Equilibrium in the Turbulent, Multiphase ISM  

E-print Network

We use numerical simulations of turbulent, multiphase, self-gravitating gas orbiting in model disk galaxies to study the relationships among pressure, the vertical gas distribution, and the ratio of dense to diffuse gas. We show that the disk height and mean midplane pressure are consistent with effective hydrostatic equilibrium, provided that the turbulent vertical velocity dispersion and gas self-gravity are included. Mass-weighted pressures are an order of magnitude higher than the midplane pressure because self-gravity concentrates gas and increases the pressure in clouds. We also investigate the ratio Rmol=M(H2)/M(HI) for our simulations. Blitz and Rosolowsky (2006) showed that Rmol is proportional to the estimated midplane pressure. For model series in which the epicyclic frequency, kappa, and gas surface density, Sigma, are proportional, we recover the empirical relation. For other model series in which kappa and Sigma are independent, the midplane pressure and Rmol are not well correlated. We conclude that the molecular fraction -- and star formation rate -- of a galactic disk inherently depends on its rotational state, not just the local values of Sigma and the stellar density rho*. The empirical correlation between Rmol and midplane pressure implies that the "environmental parameters" kappa, Sigma, and rho* are interdependent in real galaxies, presumably as a consequence of evolution toward states with Toomre Q near unity. We note that Rmol in static models far exceeds both the values in our turbulent simulations and observed values, implying that turbulence is crucial to obtaining a realistic molecular fraction in the ISM.

H. Koyama; E. C. Ostriker

2008-12-10

244

Vertical Velocity Measurements in Warm Stratiform Clouds  

NASA Astrophysics Data System (ADS)

Measurements of vertical air motion in warm boundary layer clouds are key for quantitatively describing cloud-scale turbulence and for improving our understanding of cloud and drizzle microphysical processes. Recently, a new technique that produces seamless measurements of vertical air velocity in the cloud and sub-cloud layers for both drizzling and non-drizzling stratocumulus clouds has been developed. The technique combines radar Doppler spectra-based retrievals of vertical air motion in cloud and light drizzle conditions with a novel neural network analysis during heavily drizzling periods. Observations from Doppler lidars are used to characterize sub-cloud velocities and to evaluate the performance of the technique near the cloud base. The technique is applied to several cases of stratiform clouds observed by the ARM Mobile Facility during the Two-Column Aerosol Project (TCAP) campaign in Cape Cod. The observations clearly illustrate coupling of the sub-cloud and cloud layer turbulent structures.

Luke, E. P.; Kollias, P.

2013-12-01

245

Purification process for vertically aligned carbon nanofibers  

NASA Technical Reports Server (NTRS)

Individual, free-standing, vertically aligned multiwall carbon nanotubes or nanofibers are ideal for sensor and electrode applications. Our plasma-enhanced chemical vapor deposition techniques for producing free-standing and vertically aligned carbon nanofibers use catalyst particles at the tip of the fiber. Here we present a simple purification process for the removal of iron catalyst particles at the tip of vertically aligned carbon nanofibers derived by plasma-enhanced chemical vapor deposition. The first step involves thermal oxidation in air, at temperatures of 200-400 degrees C, resulting in the physical swelling of the iron particles from the formation of iron oxide. Subsequently, the complete removal of the iron oxide particles is achieved with diluted acid (12% HCl). The purification process appears to be very efficient at removing all of the iron catalyst particles. Electron microscopy images and Raman spectroscopy data indicate that the purification process does not damage the graphitic structure of the nanotubes.

Nguyen, Cattien V.; Delziet, Lance; Matthews, Kristopher; Chen, Bin; Meyyappan, M.

2003-01-01

246

Enhanced vertical inhomogeneity in turbulent rotating convection.  

PubMed

In this Letter we report experimental evidence that rotation enhances vertical inhomogeneity in turbulent convection, in spite of the increased columnar flow ordering under rotation. Measurements using stereoscopic particle image velocimetry have been carried out on turbulent rotating convection in water. At constant Rayleigh number Ra=1.11 x 10(9) several rotation rates have been used, so that the Rossby number takes values from Ro=infinity (no rotation) to 0.09 (strong rotation). The three-component velocity data, obtained at two vertical positions, are used to investigate the anisotropy of the flow through the invariants of the Reynolds-stress anisotropy tensor and the Lumley triangle, as well as to correlate the vertical velocity and vorticity. In the center plane rotation causes the turbulence to be "rodlike," while closer to the top plate a trend toward isotropy is observed. PMID:18999750

Kunnen, R P J; Clercx, H J H; Geurts, B J

2008-10-24

247

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

248

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

Microsoft Academic Search

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

Y. B. Acharya; A. Jayaraman

2006-01-01

249

MEASUREMENT OF BI-DIRECTIONAL AMMONIA FLUXES OVER SOYBEAN USING MODIFIED BOWEN-RATIO TECHNIQUE  

EPA Science Inventory

Measurements of bi-directional ammonia exchange over a fertilized soybean canopy are presented for an 8-week period during the summer of 2002. The modified Bowne-ratio approach was used to determine fluxes from vertical NH3 and temperature gradients in combination with eddy covar...

250

Developments in the Use of Proximity and Ratio Cues in Velocity Judgments.  

ERIC Educational Resources Information Center

Young children's responses to a velocity inference task based on static pictorial stimuli giving cues of proximity and ratio were examined. Subjects (N=65) in preschool through second grade viewed pictures of snails moving horizontally or spiders suspended vertically and were asked to estimate which competitor would reach its destination first.…

Shire, Beatrice; Durkin, Kevin

251

Optimal Design of Gear Ratios and Offset for Energy Conservation of an Articulated Manipulator  

Microsoft Academic Search

It is important to minimize the energy dissipated by the reduction gears and motors in a three-jointed vertically articulated manipulator. This paper proposes an optimal design method for simultaneously determining eight design variables, which are three motor masses, three reduction gear ratios, a counterbalancer mass for the third link and an offset between the first and the second links. Using

Teruyuki Izumi; Hai Zhou; Zuowei Li

2009-01-01

252

Distribution and vertical dynamics of planktonic communities at Sofala Bank, Mozambique  

NASA Astrophysics Data System (ADS)

Coastal ecosystem processes are largely influenced by the interaction of different factors operating at various temporal and spatial scales, specifically those responsible for primary production patterns that modulate zooplankton and subsequent trophic levels. Hydrological processes, such as tidal cycles and coastal currents, nutrients availability, phytoplankton groups (studied through algal pigment signatures analysed by HPLC), and zooplankton abundance and distribution were investigated at the Sofala Bank (Mozambique), with special emphasis on their horizontal distribution and vertical dynamics (48 h). Horizontal distribution has shown inshore-offshore gradients in all analysed parameters, as well as inshore waters intrusion probably related to Zambezi River delta runoff. Tidal currents were responsible for major hydrological vertical variations and for horizontal and vertical advection of phytoplankton biomass in the surface and deepest layers, respectively. Nutrient concentrations were typical from oligotrophic regions, and nutrient ratios were strongly influenced by depleted nitrate + nitrite concentrations, indicating low estuarine discharges typical from the dry season. The very low N:P ratio obtained suggests strong nitrogen limitation to phytoplankton communities, supporting the low phytoplankton abundance observed. Both phytoplankton pigments and zooplankton were found mainly near the bottom (40 m depth), despite the latter displayed vertical migrations triggered by light variations. Phytoplankton community was dominated by microflagellates, specifically prymnesiophyceans, and behaved as a whole, except Cyanobacteria that displayed vertical distribution movements different from other phytoplankton groups, being mainly concentrated at mid-water column depths (10-20 m). This investigation enhances physico-chemical phenomena and their importance determining the planktonic communities vertical dynamics at Sofala Bank, a tropical coastal ecosystem of the Western Indian Ocean where planktonic dynamics are still poorly described and understood.

Leal, M. C.; Sá, C.; Nordez, S.; Brotas, V.; Paula, J.

2009-10-01

253

CIRSS vertical data integration, San Bernardino study  

NASA Technical Reports Server (NTRS)

The creation and use of a vertically integrated data base, including LANDSAT data, for local planning purposes in a portion of San Bernardino County, California are described. The project illustrates that a vertically integrated approach can benefit local users, can be used to identify and rectify discrepancies in various data sources, and that the LANDSAT component can be effectively used to identify change, perform initial capability/suitability modeling, update existing data, and refine existing data in a geographic information system. Local analyses were developed which produced data of value to planners in the San Bernardino County Planning Department and the San Bernardino National Forest staff.

Hodson, W.; Christenson, J.; Michel, R. (principal investigators)

1982-01-01

254

Critique of the vertical gradient of gravity  

NASA Technical Reports Server (NTRS)

Growing interest in high precision studies of the Earth's gravitational field warrant a critical review of precision requirements to yield useful results. Several problems are now under consideration. All of these problems involve, more or less, the precise value of the vertical gradients of gravity. The principle conclusion from this review is that the essential absence of Free Air Vertical Gravity Gradient control and actual values of gravimeter calibrations require serious attention. Large errors in high topography on official published gravity maps also cannot be ignored.

Hammer, Sigmund

1989-01-01

255

Concepts for generating optimum vertical flight profiles  

NASA Technical Reports Server (NTRS)

Algorithms for generating optimum vertical profiles are derived and examined. These algorithms form the basis for the design of onboard flight management concepts. The variations in the optimum vertical profiles (resulting from these concepts) due to variations in wind, takeoff weight, and range-to-destination are presented. Further considerations for mechanizing two different onboard methods of computing near-optimum flight profiles are then outlined. Finally, the results are summarized, and recommendations are made for further work. Technical details of optimum trajectory design, steering requirements for following these trajectories, and off-line computer programs for testing the concepts are included.

Sorensen, J. A.

1979-01-01

256

Photochemistry and vertical mixing. [in Uranus atmosphere  

NASA Technical Reports Server (NTRS)

Earth-based observations relevant to the question of photochemistry and vertical mixing are discussed. Phytolysis of methane, the only known photochemically active volatile in the Uranian atmosphere, produces heavier hydrocarbons, the most abundant of which are ethane, acetylene, and the polyacetylenes. Unlike Jupiter and Saturn, these hydrocarbon products condense at the low temperatures prevalent in the middle atmosphere. Contrary to the pre-Voyager notion that the atmosphere of Uranus is remarkable clear, it is found that the aerosols are widely and extensively distributed. Despite its photodestruction, methane remains stable in the Uranian atmosphere. The vertical mixing on Uranus is found to be the least efficient of any of the planetary atmospheres.

Atreya, S. K.; Sandel, B. R.; Romani, P. N.

1991-01-01

257

Geysering inhibitor for vertical cryogenic transfer piping  

NASA Technical Reports Server (NTRS)

Geysering (i.e., the expulsion of boiling liquid and its vapor from a vertical tube) has been a problem for the missile industry in long vertical cryogenic propellant feed lines connecting the launch vehicle propellant tank with the rocket engines. A proposed novel method of inhibiting geysering and the associated pressure gradients provides a self-starting self-regulating action that is not dependent on other active systems or components. The inhibiting action is attained by incorporating a concentric tube within the main transfer tube to prevent constriction of natural convective flow.

Howard, F. S.

1973-01-01

258

Fundamental and effective Yang-Mills vertices  

SciTech Connect

Calorons and plane waves within and in between them collectively give rise to a thermal ground state. The latter provides a homgeneous energy density and a negative pressure, and it induces quasiparticle masses to part of the propagating spectrum of deconfining SU(2) Yang-Mills thermodynamics (dynamical gauge-symmetry breaking). In the present talk we discuss the role of a single caloron in inducing effective local vertices, characterized by powers of h, mediating the interaction of plane waves which propagate over large distances. The constraints on momentum transfers through effective 4-vertices are revisited.

Hofmann, Ralf [ITP, Universitaet Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany)

2012-09-26

259

Discovering Phi: The Golden Ratio  

NSDL National Science Digital Library

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

AMPS GK-12 Program,

260

Higgs boson hadronic branching ratios at the ILC  

SciTech Connect

We present a study of the Higgs boson decay branching ratios to bb, cc, and gluons, one of the cornerstones of the physics program at the International Linear Collider. A standard model Higgs boson of 120 GeV mass, produced in the Higgs-strahlung process at {radical}(s)=250 GeV, was investigated using the full detector simulation and reconstruction procedures. The analysis was performed in the framework of the Silicon Detector concept with full account of inclusive standard model backgrounds. The selected decay modes contained two heavy flavor jets in the final state and required excellent flavor tagging through precise reconstruction of interaction and decay vertices in the detector. A new signal discrimination technique using correlations of neural network outputs was used to determine the branching ratios and estimate their uncertainties, 4.8%, 8.4%, and 12.2% for bb, cc, and gluons, respectively.

Banda, Yambazi; Lastovicka, Tomas; Nomerotski, Andrei [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)

2010-08-01

261

Morphologic assessment for glaucoma in the Multicenter Uveitis Steroid Treatment (MUST) Trial  

PubMed Central

Purpose To compare Reading Center (RC) cup-to-disc ratio (CDR) assessment from stereoscopic photographs with clinician estimation in a uveitis clinical trial. Methods Clinical estimation of CDR was performed by ophthalmologists via dilated biomicroscopy. Photographic evaluation was performed at an independent RC by masked, certified evaluators. Quality control was performed by repeat grading of 77 randomly selected images. Results Among 481 eyes with uveitis, 353 eyes had clinical and photographic grades for CDR. Agreement between clinical and RC grading was fair, with exact agreement in 29%. Agreement within 0.1 and 0.2 CDR were 70% and 93%, respectively (wkappa=0.34). Inter-grader reproducibility at the RC was better (wkappa=0.59, ICC 0.74). Conclusion Morphologic assessment of cup to disc ratio is an important outcome and safety measure for determining glaucomatous damage in clinical trials. Masked RC measurements are more likely to be accurate than biomicroscopic grading in identifying meaningful anatomical change associated with glaucoma. PMID:21770805

Gangaputra, Sapna; Altaweel, Michael M.; Peng, Qian; Friedman, David S.; Rao, P. Kumar; Foster, C. Stephen; Kim, Rosa Y.; Reed, Susan B.; Srivastava, Sunil K.; Wong, Ira G.; Kempen, John H.

2013-01-01

262

Optic disc boundary segmentation from diffeomorphic demons registration of monocular fundus image sequences versus 3D visualization of stereo fundus image pairs for automated early stage glaucoma assessment  

NASA Astrophysics Data System (ADS)

Despite the current availability in resource-rich regions of advanced technologies in scanning and 3-D imaging in current ophthalmology practice, world-wide screening tests for early detection and progression of glaucoma still consist of a variety of simple tools, including fundus image-based parameters such as CDR (cup to disc diameter ratio) and CAR (cup to disc area ratio), especially in resource -poor regions. Reliable automated computation of the relevant parameters from fundus image sequences requires robust non-rigid registration and segmentation techniques. Recent research work demonstrated that proper non-rigid registration of multi-view monocular fundus image sequences could result in acceptable segmentation of cup boundaries for automated computation of CAR and CDR. This research work introduces a composite diffeomorphic demons registration algorithm for segmentation of cup boundaries from a sequence of monocular images and compares the resulting CAR and CDR values with those computed manually by experts and from 3-D visualization of stereo pairs. Our preliminary results show that the automated computation of CDR and CAR from composite diffeomorphic segmentation of monocular image sequences yield values comparable with those from the other two techniques and thus may provide global healthcare with a cost-effective yet accurate tool for management of glaucoma in its early stage.

Gatti, Vijay; Hill, Jason; Mitra, Sunanda; Nutter, Brian

2014-03-01

263

Highly ordered vertical GaAs nanowire arrays with dry etching and their optical properties  

NASA Astrophysics Data System (ADS)

We report fabrication methods, including metal masks and dry etching, and demonstrate highly ordered vertical gallium arsenide nanowire arrays. The etching process created high aspect ratio, vertical nanowires with insignificant undercutting from the mask, allowing us to vary the diameter from 30 nm to 400 nm with a pitch from 250 nm to 1100 nm and length up to 2.2 ?m. A diameter to pitch ratio of ˜68% was achieved. We also measured the reflectance from the nanowire arrays and show experimentally diameter-dependent strong absorption peaks resulting from resonant optical mode excitations within these nanowires. The reflectance curves match very well with simulations. The work done here paves the way towards achieving high efficiency solar cells and tunable photodetectors using III-V nanowires.

Dhindsa, Navneet; Chia, Andrew; Boulanger, Jonathan; Khodadad, Iman; LaPierre, Ray; Saini, Simarjeet S.

2014-08-01

264

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.

265

Vertical And Meridional Distribution Of Various Hydrocarbons In Saturn's Stratosphere From Cassini/ Cirs Limb Observations.  

NASA Astrophysics Data System (ADS)

Saturn's stratosphere harbors a rich photochemistry initiated by the photolysis of methane (CH4) by solar UV at high altitude, leading to the formation of many hydrocarbons. Their vertical profiles are governed by their chemical lifetime as well as vertical motions (molecular and eddy diffusion, vertical advection). Their variations with time and latitude are due to seasonal changes in the incoming UV flux, which modulates the hydrocarbons production and destruction rates, and are also affected by the meridional circulation in the stratosphere of Saturn, still poorly known. We have analyzed limb observations performed by the Composite InfraRed Spectrometer (CIRS) instrument onboard the Cassini spacecraft, in order to investigate the temperature and composition of Saturn's stratosphere. Spectra were acquired at twenty different latitudes between 80°S and 45°N from March 2005 to January 2008, which corresponds to mid-summer in the southern hemisphere. Using a line-by-line radiative transfer model, we were able to retrieve the temperature vertical profiles, as well as the volume mixing ratio vertical profiles of acetylene (C2H2) and ethane (C2H6) from 5 mbar to 5 µbar and propane (C3H8) around 1 mbar. Our data analysis brings new and precious information at high altitude, with a high vertical resolution as well as an extended latitudinal coverage with respect to previous observations. We will present our results about the vertical and meridional distribution of these hydrocarbons and compare our retrieved abundances with previous measurements by Greathouse et al. (2005) and Howett et al. (2007). We will also analyze our derived distributions in the light of photochemical models (Moses and Greathouse, 2005) and discuss what constraints can we bring on the chemistry and dynamical phenomona in Saturn's stratosphere.

Guerlet, Sandrine; Fouchet, T.; Bézard, B.; Simon-Miller, A. A.; Flasar, F. M.

2008-09-01

266

Vertical export of particulate organic carbon: Attenuation, composition and loss rates in the northern Barents Sea  

NASA Astrophysics Data System (ADS)

The fate of primary production (PP) is closely linked to the ecosystem structure in aquatic environments. High pelagic consumption and recycling reduce quantity and quality of vertically exported organic material, while low to moderate pelagic consumption allows more carbon of higher quality to reach benthic communities. To evaluate the driving forces influencing changes in quantity and composition of vertical flux with depth and environmental conditions in ice-covered waters, short-term sediment trap deployments at 6-8 depths from 20 to 200 m were conducted. Eleven stations in the northern Barents Sea were investigated during early, peak and late bloom scenarios in 2003-2005. Vertical particulate organic carbon (POC) export ranged 140-760 mg C m -2 d -1 at 30 m and 58-720 mg C m -2 d -1 at 90 m depth. Strongest vertical carbon flux attenuation was observed during peak bloom scenarios. The pycnocline always defined the depth of the strongest attenuation. The POC export was highly correlated with Chl a flux ( r2=0.89) and with a low POC/Chl a ratio, this indicates that fresh material is being exported to depth. A tight coupling between POC export at 90 m and particulate PP ( r2=0.61) was observed and suggests that on an average 36% of daily PP was exported as POC. Deep vertical mixing observed in the Polar Front or less stable water masses did, however, enhance the vertical export and loss rates considerably. Annual estimates of vertical POC export to PP, suggests weaker retention, and thus stronger pelagic-benthic coupling in Arctic compared to the Atlantic region of the Barents Sea.

Reigstad, Marit; Wexels Riser, Christian; Wassmann, Paul; Ratkova, Tatjana

2008-10-01

267

Linear models in vertical ionosperic sounding  

Microsoft Academic Search

Summary  The paper deals with selecting optimum models for computing the vertical distribution of the electron concentration of ionospheric plasma. It is demonstrated that, with a view to the proposed average criterion, a model can be found, which utilizes the information contained in observed values to a better advantage than previous models.

Jaromír Bordovský; Jan Šomvarský

1990-01-01

268

Vertical Production Networks in Multinational Firms  

Microsoft Academic Search

In recent decades, growth of world trade has been driven largely by rapid growth of trade in intermediate inputs. Much of input trade involves multinational firms locating input processing in their foreign affiliates, thereby creating global vertical production networks. We use firm-level data on U.S. multinationals to examine trade in intermediate inputs for further processing between parent firms and their

Gordon H. Hanson; Raymond J. Mataloni; Matthew J. Slaughter

2005-01-01

269

Scaling of vertical temperature gradient spectra  

Microsoft Academic Search

Tests of a formula derived for the cutoff wave number of vertical temperature gradient spectra, using data taken in the upper layers of the North Pacific, show encouraging results. To derive this formula, the cutoff wave number is assumed to be the Batchelor wave number, with kinetic energy dissipation calculated by combining a form used in the atmosphere for caLculating

D. R. Caldwell; T. M. Dillon; J. M. Brubaker; P. A. Newberger; C. A. Paulson

1980-01-01

270

A Simple Vertical Slab Gel Electrophoresis Apparatus.  

ERIC Educational Resources Information Center

Describes an inexpensive, easily constructed, and safe vertical slab gel kit used routinely for sodium dodecyl sulphate-polyacrylamide gel electrophoresis research and student experiments. Five kits are run from a single transformer. Because toxic solutions are used, students are given plastic gloves and closely supervised during laboratory…

Carter, J. B.; And Others

1983-01-01

271

Performance of diffused vertical multijunction solar cell  

Microsoft Academic Search

The paper presents an analytical investigation of the conversion efficiency of a diffused vertical multijunction solar cell, neglecting the effects of surface recombination velocity and non-Ohmic contacts. Optimal efficiency was sought in relation to the width of the p and n regions and the magnitude of the built-in field. It was found that the conversion efficiency was largely dependent on

M. S. Sodha; A. K. Agarwal

1976-01-01

272

Performance of diffused vertical multijunction solar cell  

Microsoft Academic Search

From the behavior of the conversion efficiency of vertical multijunction diffused solar cell, it is concluded that efficiency is largely dependent on the built-in-field. This built-in-field, in turn, is a function of the equilibrium carrier concentration profile which is governed by the diffusion technique and can be controlled easily to obtain optimum results.

M. S. Sodha; A. K. Agarwal

1976-01-01

273

Vertically Equated Tests: Fact or Phantom?  

ERIC Educational Resources Information Center

Conventional linear and equipercentile procedures are reviewed with an emphasis on their utility for equating achievement tests pitched at different levels of difficulty. It is argued that the equipercentile procedure is superior to the linear procedure, but that neither is very satisfactory for the vertical equating problem. (Author/JKS)

Slinde, Jeffrey A.; Linn, Robert L.

1977-01-01

274

Vertical transmission of hepatitis E virus  

Microsoft Academic Search

Little is known about vertical transmission of hepatitis E virus from infected mothers to their infants. We studied eight babies born to mothers infected with hepatitis E in third trimester. One baby was icteric at birth with elevated transaminases and four babies had anicteric hepatitis. Two babies were born with hypothermia and hypoglycaemia and died within 24 h; one had

M. S. Khuroo; S. Kamali; S. Jameel

1995-01-01

275

Vertical root fractures and their management.  

PubMed

Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

2014-03-01

276

Electrical models for vertical carbon nanotube capacitors  

Microsoft Academic Search

We present electrical models for a carbon nanotube capacitor with high capacitance per unit area. We begin by introducing the concept of using vertically grown carbon nanotubes to develop a carbon nanotube capacitor. Three potential structures of the carbon nanotube capacitor are presented. We determine the capacitance per unit area for each structure. The carbon nanotube capacitor structures exhibit capacitances

Mark M. Budnik; Eric W. Johnson; Joshua D. Wood

2008-01-01

277

Vertical root fractures and their management  

PubMed Central

Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

2014-01-01

278

Vertical motions in the equatorial middle atmosphere  

NASA Technical Reports Server (NTRS)

A single station vertical velocity equation which considers ageostrophic and diabatic effects derived from the first law of thermodynamics and a generalized thermal wind relation is presented. An analysis and verification procedure which accounts for measurement and calculation errors as well as time and space continuity arguments and theoretical predictions are described. Vertical velocities are calculated at every kilometer between 25 and 60 km and for approximately every three hours for the above diurnal period at Kourou (French Guiana), Fort Sherman (Panama Canal Zone), Ascension Island, Antigua (British West Indies) and Natal (Brazil). The results, plotted as time series cross sections, suggest vertical motions ranging in magnitude from 1 or 2 cm/sec at 30 km to as much as 15 cm/sec at 60 km. Many of the general features of the results agree well with atmospheric tidal predictions but many particular features suggest that both smaller time scale gravity waves (periods less than 6 hours) and synoptic type waves (periods greater than 1 day) may be interacting significantly with the tidal fields. The results suggest that vertical motions can be calculated for the equatorial middle atmosphere and must be considered a significant part of the motion for time scales from 8 to 24 hours.

Weisman, M. L.

1979-01-01

279

Vertical distribution of Titan's atmospheric neutral constituents  

Microsoft Academic Search

The vertical distribution of Titan's neutral atmosphere compounds is calculated from a new photochemical model extending from 40 to 1432 km. This model makes use of many updated reaction rates, and of the new scheme for methane photolysis proposed by Mordaunt et al. [1993]. The model also includes a realistic treatment of the dissociation of N2, of the deposition of

L. M. Lara; E. Lellouch; J. J. López-Moreno; R. Rodrigo

1996-01-01

280

Sexual and vertical transmission of visceral leishmaniasis.  

PubMed

Visceral leishmaniasis (VL) is an important zoonosis caused by Leishmania infantum, which has in the domestic dog its principal vertebrate host. VL is usually transmitted by phlebotomine sand flies, however atypical routes of transmission have been described. In this review we discuss the the role of sexual and vertical transmissions, and their role in the maintenance of VL in canine populations. PMID:24727504

Turchetti, Andreia P; Souza, Tayse D; Paixão, Tatiane A; Santos, Renato L

2014-01-01

281

On the Design of Vertical Hydraulic Fractures  

Microsoft Academic Search

Some of the assumptions involved in designing vertical hydraulic fractures should be critically examined as to their validity. This is done on the basis of a new width equation and a numerical design procedure. It is found that some of the assumptions related to the fluid mechanics of the problem greatly affect the computed results and therefore deserve special attention.

Abbas Daneshy

1973-01-01

282

Vertical Transmission of Babesia microti, United States  

PubMed Central

Babesiosis is usually acquired from a tick bite or through a blood transfusion. We report a case of babesiosis in an infant for whom vertical transmission was suggested by evidence of Babesia spp. antibodies in the heel-stick blood sample and confirmed by detection of Babesia spp. DNA in placenta tissue. PMID:22840424

Purtill, Kerry; Wong, Susan J.; Munoz, Jose; Teal, Allen; Madison-Antenucci, Susan; Horowitz, Harold W.; Aguero-Rosenfeld, Maria E.; Moore, Julie M.; Abramowsky, Carlos; Wormser, Gary P.

2012-01-01

283

Variables determinantes en el salto vertical  

Microsoft Academic Search

Resumen Mejorar el rendimiento en el salto vertical para muchos científicos, entrenadores o atletas ha sido y sigue siendo un objeto común. Pero esta acción, como bien se sabe, depende de muchas variables, control motor, coordinación intramuscular, acción multiarticular, elevados niveles de fuerza, altos grados de potencia, buena técnica de ejecución y otras. Muchas de las pruebas establecidas para medir

Eduardo Saez; Saez de Villarreal

284

Kinematic Features of Unrestrained Vertical Arm Movements  

Microsoft Academic Search

Unrestrained human arm trajectories between point targets have been investigated using a three-dimensional tracking apparatus, the Selspot system. Movements were executed between different points in a vertical plane under varying conditions of speed and hand-held load. In contrast to past results which emphasized the straightness of hand paths, movement regions were discovered in which the hand paths were curved. All

CHRISTOPHER G. ATKESON; JOHN M. HOLLERBACH

1985-01-01

285

An Economic Theory of Vertical Restraints  

Microsoft Academic Search

Vertical restraints imposed by manufacturers on the prices, locations, and sales of retail firms represent a puzzling departure from the simple price-mediated exchange of conventional markets. In this article we analyze the theoretical basis for these restraints. In a setting where retailers inform consumers and are imperfectly competitive, and where a manufacturer has some monopoly power, we identify three potential

G. F. Mathewson; R. A. Winter

1984-01-01

286

Structure of meson-baryon interaction vertices  

E-print Network

We present a microscopic derivation of the form factors of strong-interaction piNN and piNDelta vertices within a relativistic constituent quark model. The results are compared with form factors from phenomenological meson-baryon models and recent lattice QCD calculations. We give an analytical representation of the vertex form factors suitable for applications in further studies of hadron reactions.

T. Melde; L. Canton; W. Plessas

2008-11-03

287

Vertical pump with free floating check valve  

DOEpatents

A vertical pump with a bottom discharge having a free floating check valve isposed in the outlet plenum thereof. The free floating check valve comprises a spherical member with a hemispherical cage-like member attached thereto which is capable of allowing forward or reverse flow under appropriate conditions while preventing reverse flow under inappropriate conditions.

Lindsay, Malcolm (O'Hara Township, Allegheny County, PA)

1980-01-01

288

Vertical occupational mobility and its measurement  

Microsoft Academic Search

This paper describes a number of alternative approaches to devising a vertical occupational scale and compares the outcomes of different scales on calculations of occupational mobility. The paper describes the conceptual issues relevant to calculating occupational mobility and documents the measurement error embedded in the choice of measure, as applied to different data sets. The ranking schemes used include SOC

Shirley Dex; Joanne Lindley; Kelly Ward

2007-01-01

289

Analysis of Group Conversations: Modeling Social Verticality  

E-print Network

-Perez 11.1 Introduction Social interaction is a fundamental aspect of human life and is also a key research quality, speaking style, intonation) and also through visual cues (gestures, body posture, facial]. It relates to power, status, dominance, leadership, and other related concepts. The vertical dimension

Gatica-Perez, Daniel

290

Optical Simulation of Axially Symmetrical Vertically Aligned Liquid Crystal Displays With Circularly Symmetric Iso-Contrast  

Microsoft Academic Search

This investigation reports the optical simulation of axially symmetric vertically aligned liquid crystal displays (ASVA LCDs). The circularly symmetric iso-light leakage and iso-transmittance contours of one subpixel result in the circularly symmetric iso-contrast contours. The contrast ratio of the area close to - and -axes at a polar angle of around 30 exceeds 10. The LCs near some azimuthal angles

Cheng-Kai Liu; Chi-Lun Ting; Ming-Shian Li; Andy Ying-Guey Fuh; Ko-Ting Cheng

2011-01-01

291

High transmittance of a twisted-vertical aligned liquid crystal display  

Microsoft Academic Search

A high transmittance continuum domain twisted-vertical alignment (CDTVA) liquid crystal display (LCD) without domain walls defect and complex fabrication process has been developed. The CDTVA mode has no optical schlieren pattern occurring in the TVA cell. The optimum conditions for liquid crystal phase retardation (Gamma) and cell gap-to-helical pitch ratio (d\\/p) were studied using three-dimensional finite element simulation, which showed

Cheng-Chung Peng; Kuei-Chu Hsu; Jin-Jei Wu; Shih-Hung Fan; Hsin-Ta Lee; Yuhren Shen

2010-01-01

292

Vertical Type Organic Transistor Using C60 and its Application for OLET  

Microsoft Academic Search

We have fabricated static induction transistor of vertical type using C60 with high carrier mobility as n-type organic semiconductor material to improve the characteristics of organic transistor. The effects of thin film thickness and the rate of deposition on the current-voltage and on-off ratio of transistor were investigated. And, we also studied the surface morphology of C60 layer under various

Se Young Oh; Hee Jeong Kim; Sun Kak Hwang

2006-01-01

293

Growth process conditions of vertically aligned carbon nanotubes using plasma enhanced chemical vapor deposition  

Microsoft Academic Search

The growth of vertically aligned carbon nanotubes using a direct current plasma enhanced chemical vapor deposition system is reported. The growth properties are studied as a function of the Ni catalyst layer thickness, bias voltage, deposition temperature, C2H2:NH3 ratio, and pressure. It was found that the diameter, growth rate, and areal density of the nanotubes are controlled by the initial

M. Chhowalla; K. B. K. Teo; C. Ducati; N. L. Rupesinghe; G. A. J. Amaratunga; A. C. Ferrari; D. Roy; J. Robertson; W. I. Milne

2001-01-01

294

Conjugate Effects on Steady Laminar Natural Convection Heat Transfer in Vertical Eccentric Annuli  

Microsoft Academic Search

Combined conduction-free convection heat transfer in vertical eccentric annuli is numerically investigated using finite-difference technique. Numerical results are presented for a fluid of Prandtl number 0.7 in an annulus of radius ratio 0.5 and dimensionless eccentricity 0.5. The conjugation effect on the induced flow rate and the total heat absorbed in the annulus is presented for the case of one

Maged A. I. El-Shaarawi; Esmail M. A. Mokheimer; Ahmad Jamal

2005-01-01

295

High-capacity free-space optical interconnects based on vertical cavity surface emitting lasers (VCSEL's)  

Microsoft Academic Search

Gaussian diffraction model is employed to analyze the optimal design of free-space optical interconnects (FSOI’s) based on the arrays of multi-tranverse mode vertical cavity surface emitting lasers (VCSEL’s), microlenses, and photodetectors. The optical channel crosstalk and the signal-to-noise ratio (SNR) are analyzed in relation to the multi-transverse mode VCSEL’s. We have found that the positioning of VCSEL’s relative to the

Rong Wang; ALEKSANDAR D. RAKIC; MARIAN L. MAJEWSKI

2000-01-01

296

Triboelectric series and charging properties of plastics using the designed vertical-reciprocation charger  

Microsoft Academic Search

A triboelectrostatic separation system consists of a tribo-charging of materials and a separation of the charged materials in an electric field. Selective charging and optimum charge density (charge-to-mass ratio: nC\\/g) of materials in tribo-charging are the most important parameters for separation efficiency. In this study, a new tribo-charger set was made by combining a vertical reciprocator and various charger materials,

Chul Hyun Park; Jai Koo Park; Ho Seok Jeon; Byoung Chul Chun

2008-01-01

297

Isotope ratios in photosynthetic oxygen.  

PubMed

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

Metzner, H; Fischer, K; Bazlen, O

1979-11-01

298

A Ratio Explanation for Evolution.  

ERIC Educational Resources Information Center

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

Riss, Pam Helfers

1993-01-01

299

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

300

Bulletin of the Seismological Society of America, Vol. 92, No. 8, pp. 31523164, December 2002 Properties of Vertical Ground Motions  

E-print Network

similar to the existing shear-modulus reduction curves. The results of this study suggest that, for most/H) ratio for re- sponse spectra, and propagates the resulting motion through the soil column as a vertically incident P wave. In the absence of data on strain-dependent soil properties in compressional

Beresnev, Igor

301

Effect of intermittent operation on contaminant removal and plant growth in vertical flow constructed wetlands: A microcosm experiment  

Microsoft Academic Search

The influences of intermittent operation and different length of drying time on contaminant removal as well as wetland plant growth in vertical flow constructed wetlands (VFCWs) were investigated in this study. Microcosm wetlands planted with Phragmites australis were subjected to a 4-month experiment involving different operations (continuously and intermittently flood) and time ratios of flood to drain (F\\/D) with the

Wenlin Jia; Jian Zhang; Juan Wu; Huijun Xie; Bo Zhang

2010-01-01

302

The vertical response of an ocean bottom seismometer: Analysis of the Lopez Island vertical transient tests  

Microsoft Academic Search

A lumped-parameter model was developed to predict the response of an ocean bottom seismometer, resting on relatively non-stiff sediments, to vertical ground-motion. The model predictions were compared with the response of an instrument on a foundation of foam rubber to a sinusoidal input. Comparison of the model data to the measured Lopez Island vertical transient test data showed that bearing

Steven J. Zelikovitz; WILLIAM A. PROTHERO JR

1981-01-01

303

Effect of gravity on vertical eye position.  

PubMed

There is growing evidence that gravity markedly influences vertical eye position and movements. A new model for the organization of brainstem upgaze pathways is presented in this review. The crossing ventral tegmental tract (CVTT) could be the efferent tract of an "antigravitational" pathway terminating at the elevator muscle motoneurons in the third nerve nuclei and comprising, upstream, the superior vestibular nucleus and y-group, the flocculus, and the otoliths. This pathway functions in parallel to the medial longitudinal fasciculus pathways, which control vertical eye movements made to compensate for all vertical head movements and may also comprise the "gravitational" vestibular pathways, involved in the central reflection of the gravity effect. The CVTT could provide the upgaze system with the supplement of tonic activity required to counteract the gravity effect expressed in the gravitational pathway, being permanently modulated according to the static positions of the head (i.e., the instantaneous gravity vector) between a maximal activity in the upright position and a minimal activity in horizontal positions. Different types of arguments support this new model. The permanent influence of gravity on vertical eye position is strongly suggested by the vertical slow phases and nystagmus observed after rapid changes in hypo- or hypergravity. The chin-beating nystagmus, existing in normal subjects with their head in the upside-down position, suggests that gravity is not compensated for in the downgaze system. Upbeat nystagmus due to brainstem lesions, most likely affecting the CVTT circuitry, is improved when the head is in the horizontal position, suggesting that this circuitry is involved in the counteraction of gravity between the upright and horizontal positions of the head. In downbeat nystagmus due to floccular damage, in which a permanent hyperexcitation of the CVTT could exist, a marked influence of static positions of the head is also observed. Finally, the strongest argument supporting a marked role of gravity in vertical eye position is that the eye movement alterations observed in the main, typical physiological and pathological conditions are precisely those that would be expected from a direct effect of gravity on the eyeballs, with, moreover, no single alternative interpretation existing so far that could account for all these different types of findings. PMID:19645894

Pierrot-Deseilligny, C

2009-05-01

304

Optomechanical Raman-Ratio Thermometry  

E-print Network

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

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

2014-06-27

305

Optomechanical Raman-Ratio Thermometry  

E-print Network

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

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

2014-01-01

306

Rates, Ratios, Percents, and Proportions  

NSDL National Science Digital Library

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

hbinggeli

2010-10-22

307

Sex ratios in bumble bees  

PubMed Central

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

Bourke, A. F. G.

1997-01-01

308

Measurement of Tau branching ratios  

Microsoft Academic Search

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

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

1992-01-01

309

Rational Industrial Water Reuse Ratios  

NASA Astrophysics Data System (ADS)

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

Liaw, Chao-Hsien; Chen, Liang-Ching

2004-08-01

310

ARM Energy Balance Bowen Ratio (EBBR) station: surf. heat flux and related data, 30-min  

DOE Data Explorer

The Energy Balance Bowen Ratio (EBBR) system produces 30-min 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. 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, David

311

Ultimately short ballistic vertical graphene Josephson junctions  

PubMed Central

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale. PMID:25635386

Lee, Gil-Ho; Kim, Sol; Jhi, Seung-Hoon; Lee, Hu-Jong

2015-01-01

312

Ultimately short ballistic vertical graphene Josephson junctions  

NASA Astrophysics Data System (ADS)

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale.

Lee, Gil-Ho; Kim, Sol; Jhi, Seung-Hoon; Lee, Hu-Jong

2015-01-01

313

Vertical Landing Aerodynamics of Reusable Rocket Vehicle  

NASA Astrophysics Data System (ADS)

The aerodynamic characteristics of a vertical landing rocket are affected by its engine plume in the landing phase. The influences of interaction of the engine plume with the freestream around the vehicle on the aerodynamic characteristics are studied experimentally aiming to realize safe landing of the vertical landing rocket. The aerodynamic forces and surface pressure distributions are measured using a scaled model of a reusable rocket vehicle in low-speed wind tunnels. The flow field around the vehicle model is visualized using the particle image velocimetry (PIV) method. Results show that the aerodynamic characteristics, such as the drag force and pitching moment, are strongly affected by the change in the base pressure distributions and reattachment of a separation flow around the vehicle.

Nonaka, Satoshi; Nishida, Hiroyuki; Kato, Hiroyuki; Ogawa, Hiroyuki; Inatani, Yoshifumi

314

Lunar vertical-shaft mining system  

NASA Technical Reports Server (NTRS)

This report proposes a method that will allow lunar vertical-shaft mining. Lunar mining allows the exploitation of mineral resources imbedded within the surface. The proposed lunar vertical-shaft mining system is comprised of five subsystems: structure, materials handling, drilling, mining, and planning. The structure provides support for the exploration and mining equipment in the lunar environment. The materials handling subsystem moves mined material outside the structure and mining and drilling equipment inside the structure. The drilling process bores into the surface for the purpose of collecting soil samples, inserting transducer probes, or locating ore deposits. Once the ore deposits are discovered and pinpointed, mining operations bring the ore to the surface. The final subsystem is planning, which involves the construction of the mining structure.

Introne, Steven D. (editor); Krause, Roy; Williams, Erik; Baskette, Keith; Martich, Frederick; Weaver, Brad; Meve, Jeff; Alexander, Kyle; Dailey, Ron; White, Matt

1994-01-01

315

Ultimately short ballistic vertical graphene Josephson junctions.  

PubMed

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale. PMID:25635386

Lee, Gil-Ho; Kim, Sol; Jhi, Seung-Hoon; Lee, Hu-Jong

2015-01-01

316

Extreme wave runup on a vertical cliff  

NASA Astrophysics Data System (ADS)

Wave impact and runup onto vertical obstacles are among the most important phenomena which must be taken into account in the design of coastal structures. From linear wave theory, we know that the wave amplitude on a vertical wall is twice the incident wave amplitude with weakly nonlinear theories bringing small corrections to this result. In this present study, however, we show that certain simple wave groups may produce much higher runups than previously predicted, with particular incident wave frequencies resulting in runup heights exceeding the initial wave amplitude by a factor of 5, suggesting that the notion of the design wave used in coastal structure design may need to be revisited. The results presented in this study can be considered as a note of caution for practitioners, on one side, and as a challenging novel material for theoreticians who work in the field of extreme wave-coastal structure interaction.

Carbone, Francesco; Dutykh, Denys; Dudley, John M.; Dias, FréDéRic

2013-06-01

317

Vertical dynamics of disk galaxies in MOND  

E-print Network

We investigate the possibility of discriminating between Modified Newtonian Dynamics (MOND) and Newtonian gravity with dark matter, by studying the vertical dynamics of disk galaxies. We consider models with the same circular velocity in the equatorial plane (purely baryonic disks in MOND and the same disks in Newtonian gravity embedded in spherical dark matter haloes), and we construct their intrinsic and projected kinematical fields by solving the Jeans equations under the assumption of a two-integral distribution function. We found that the vertical velocity dispersion of deep-MOND disks can be much larger than in the equivalent spherical Newtonian models. However, in the more realistic case of high-surface density disks this effect is significantly reduced, casting doubts on the possibility of discriminating between MOND and Newtonian gravity with dark matter by using current observations.

Carlo Nipoti; Pasquale Londrillo; HongSheng Zhao; Luca Ciotti

2007-04-24

318

Experimental Studies in Helicopter Vertical Climb Performance  

NASA Technical Reports Server (NTRS)

Data and analysis from an experimental program to measure vertical climb performance on an eight-foot model rotor are presented. The rotor testing was performed using a unique moving-model facility capable of accurately simulating the flow conditions during axial flight, and was conducted from July 9, 1992 to July 16, 1992 at the Dynamic Model Track, or 'Long Track,' just prior to its demolition in August of 1992. Data collected during this brief test program included force and moment time histories from a sting-mounted strain gauge balance, support carriage velocity, and rotor rpm pulses. In addition, limited video footage (of marginal use) was recorded from smoke flow studies for both simulated vertical climb and descent trajectories. Analytical comparisons with these data include a series of progressively more detailed calculations ranging from simple momentum theory, a prescribed wake method, and a free-wake prediction.

McKillip, Robert M., Jr.

1996-01-01

319

Spirit 360-Degree View, Sol 388 (vertical)  

NASA Technical Reports Server (NTRS)

NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on Spirit's 388th martian day, or sol (Feb. 4, 2005). Spirit had driven about 13 meters (43 feet) uphill toward 'Cumberland Ridge' on this sol. This location is catalogued as Spirit's Site 102, Position 513. The view is presented in a vertical projection with geometric and brightness seam correction.

2005-01-01

320

Vertical spin transport in semiconductor heterostructures  

Microsoft Academic Search

The Landauer-Büttiker formalism combined with the tight-binding transfer matrix method is employed to model vertical coherent spin transport within magnetization-modulated semiconductor heterostructures based on GaAs. This formalism provides excellent physical description of recent experiments concerning the high tunneling magnetoresistance (TMR) in (Ga,Mn)As-based trilayers and highly polarized spin injection in p-(Ga,Mn)As\\/n-GaAs Zener diodes. For both the TMR and the Zener spin

P. Sankowski; P. Kacman; J. A. Majewski; T. Dietl

2007-01-01

321

Vertical shear in the Jovian equatorial zone.  

NASA Technical Reports Server (NTRS)

Jupiter photographs taken in two different wavelength regions (blue and red) are studied for clues to differing Jovian atmosphere motions. The relative motions of features visible on these photographs may be interpreted as a vertical shear at visible cloud level. The value obtained implies that the north equatorial zone must be about 0.35 deg K warmer than the adjacent equatorial zone. Deeper in the atmosphere the reverse must hold.

Layton, R. G.

1971-01-01

322

Present day vertical deformation in New Zealand  

NASA Astrophysics Data System (ADS)

New Zealand is tectonically very active. It lies along the oblique convergent plate boundary between the Pacific and Australian plate. In the North Island active tectonics is dominated by westward subduction of the Pacific Plate beneath the eastern North Island at the Hikurangi Trench, strike-slip faulting in the upper plate, and back-arc rifting in the central North Island. A series of very large strike-slip faults run through the South Island (Marlborough Fault System and the Alpine Fault) connecting with the Puysegur subduction zone in the south. The present day uplift rates are evaluated by analyzing data from continuous GPS stations in New Zealand. The up to 20 years of continuous GPS gives us a snapshot into the deformation rate. The average velocity is corrected for significant coseismic offsets, but the data can also be influenced by postseismic deformation, slow slip events along the Hikurangi subduction zone, volcanic deformation, as well as none tectonic local affects such as water extraction. We evaluate the interseismic vertical rate. We exclude data significantly affected by postseismic deformation from recent earthquakes and provide vertical rates both with and without correcting for slow slip events. Outside the Taupo rift zone the vertical rates are range from -6 to +6 mm/yr with uplift observed across the Alpine fault, few mm/yr uplift around the Raukumara Peninsula, northeast North Island, and subsidence along the southeast North Island, reflecting variation in plate locking. We compare the present day vertical deformation to the long-term motion along the coast determined primarily from 125,000 years old marine geological markers. The largest proportion of the New Zealand coastline (45%) is undergoing long-term tectonic uplift. Small stretches of the coastline (15%) are undergoing long-term subsidence. Areas farthest from the plate boundary (northern North Island and southeastern South Island) are assessed to be tectonically stable, in agreement with the continuous GPS data.

Hreinsdóttir, Sigrún; Wallace, Laura; Litchfield, Nicola; D'Anastasio, Elisabetta; Denys, Paul; Pearson, Christopher

2014-05-01

323

Engineering design of vertical test stand cryostat  

Microsoft Academic Search

Under Indian Institutions and Fermilab collaboration, Raja Ramanna Centre for Advanced Technology and Fermi National Accelerator Laboratory are jointly developing 2K Vertical Test Stand (VTS) cryostats for testing SCRF cavities at 2K. The VTS cryostat has been designed for a large testing aperture of 86.36 cm for testing of 325 MHz Spoke resonators, 650 MHz and 1.3 GHz multi-cell SCRF

S. K. Suhane; N. K. Sharma; S. Raghavendra; S. C. Joshi; S. Das; P. K. Kush; V. C. Sahni; P. D. Gupta; C. Sylvester; R. Rabehl; J. Ozelis

2011-01-01

324

Vertical leaf pressure filter LVAzh 225  

SciTech Connect

A new vertical lead pressure filter LVAzh 225 has been developed with an arrangement for hydraulic coke removal. Industrial trials of the filter, however, showed the service life of the rubber seals of the butterfly valves to be short, so that butterfly valves were replaced by shut-off valves with a pneumatic drive. The prototype of the LVAzh 225 leaf filter has been recommended for series production.

Fomichev, V.I.; Abramov, V.P.; Gutin, Y.V.

1984-01-01

325

Vertical Carbon Nanotube Device in Nanoporous Templates  

NASA Technical Reports Server (NTRS)

A modified porous anodic alumina template (PAA) containing a thin CNT catalyst layer directly embedded into the pore walls. CNT synthesis using the template selectively catalyzes SWNTs and DWNTs from the embedded catalyst layer to the top PAA surface, creating a vertical CNT channel within the pores. Subsequent processing allows for easy contact metallization and adaptable functionalization of the CNTs and template for a myriad of applications.

Maschmann, Matthew Ralph (Inventor); Fisher, Timothy Scott (Inventor); Sands, Timothy (Inventor); Bashir, Rashid (Inventor)

2014-01-01

326

Electrically floating, near vertical incidence, skywave antenna  

DOEpatents

An Electrically Floating, Near Vertical Incidence, Skywave (NVIS) Antenna comprising an antenna element, a floating ground element, and a grounding element. At least part of said floating ground element is positioned between said antenna element and said grounding element. The antenna is separated from the floating ground element and the grounding element by one or more electrical insulators. The floating ground element is separated from said antenna and said grounding element by one or more electrical insulators.

Anderson, Allen A.; Kaser, Timothy G.; Tremblay, Paul A.; Mays, Belva L.

2014-07-08

327

Vertical flight path steering system for aircraft  

NASA Technical Reports Server (NTRS)

Disclosed is a vertical flight path angle steering system for aircraft, utilizing a digital flight control computer which processes pilot control inputs and aircraft response parameters into suitable elevator commands and control information for display to the pilot on a cathode ray tube. The system yields desirable airplane control handling qualities and responses as well as improvements in pilot workload and safety during airplane operation in the terminal area and under windshear conditions.

Lambregts, Antonius A. (Inventor)

1983-01-01

328

Small Vertical Raceways for Rearing Juvenile Salmon  

Microsoft Academic Search

We describe a micro-vertical raceway, a small floating container, for rearing small populations of fish. The container is a 170.6-L polyethylene drum fitted to a controlled water supply. An array of these containers was used to rear juvenile salmon simultaneously in 60 groups (200 fish each) to 6.0-g size. We compared growth rates of juvenile chinook salmon (Oncorhynchus tshawytscha) reared

Ron Heintz; John Joyce

1992-01-01

329

Inverse scattering problem for quantum graph vertices  

E-print Network

We demonstrate how the inverse scattering problem of a quantum star graph can be solved by means of diagonalization of Hermitian unitary matrix when the vertex coupling is of the scale invariant (or F\\"ul\\H{o}p-Tsutsui) form. This enables the construction of quantum graphs with desired properties in a tailor-made fashion. The procedure is illustrated on the example of quantum vertices with equal transmission probabilities.

Taksu Cheon; Pavel Exner; Ondrej Turek

2011-04-06

330

Inverse scattering problem for quantum graph vertices  

SciTech Connect

We demonstrate how the inverse scattering problem of a quantum star graph can be solved by means of diagonalization of the Hermitian unitary matrix when the vertex coupling is of the scale-invariant (or Fueloep-Tsutsui) form. This enables the construction of quantum graphs with desired properties in a tailor-made fashion. The procedure is illustrated on the example of quantum vertices with equal transmission probabilities.

Cheon, Taksu; Turek, Ondrej [Laboratory of Physics, Kochi University of Technology, Tosa Yamada, Kochi 782-8502 (Japan); Exner, Pavel [Doppler Institute for Mathematical Physics and Applied Mathematics, Czech Technical University, Brehova 7, CZ-11519 Prague (Czech Republic); Nuclear Physics Institute ASCR, CZ-25068 Rez (Czech Republic)

2011-06-15

331

Structure of Meson-Baryon Interaction Vertices  

SciTech Connect

We present a microscopic derivation of the form factors of strong-interaction {pi}NN and {pi}N{delta} vertices within a relativistic constituent quark model. The results are compared with form factors from phenomenological meson-baryon models and recent lattice QCD calculations. We give an analytical representation of the vertex form factors suitable for applications in further studies of hadron reactions.

Melde, T.; Plessas, W. [Theoretische Physik, Institut fuer Physik, Karl-Franzens-Universitaet, Universitaetsplatz 5, A-8010 Graz (Austria); Canton, L. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Via F. Marzolo 8, I-35131 Padova (Italy)

2009-04-03

332

Vertical tubular reactor for microalgae cultivation  

Microsoft Academic Search

Summary Vertical glass tubular reactors, 5 cm in diameter and 2.35 m high, were used to grow several species of cyanobacteria, green algae, and diatoms. The reactors were gassed with an air\\/CO2 mixture, to supply CO2, remove O2, and provide mixing. Most of the 10 strains tested had productivities similar to those observed with mechanically mixed reactors. The advantages of

K. Miyamoto; O. Wable; J. R. Benemann

1988-01-01

333

The vertical distribution of tropospheric ammonia  

NASA Technical Reports Server (NTRS)

A one-dimensional tropospheric photochemical model is used to simulate measured profiles of NH3 obtained with the Infrared Heterodyne Radiometer. The relative roles of homogeneous loss, heterogeneous loss, and vertical eddy transport are discussed in terms of selecting parameters which best fit the measurements. The best fit was obtained for a vertical eddy diffusion coefficient of 200,000/sq cm per sec or greater (corresponding to a characteristic vertical transport time in excess of about 35 days), and a characteristic heterogeneous loss time in excess of 10 days. The characteristic homogeneous chemical loss time was found to be about 40 days at the surface and decreased to about 180 days at 10 km, and not very sensitive to model chemical perturbations. Increased ground-level concentrations of NH3 to about 10 ppb, compared to background surface concentrations of about 1 ppb, were measured several weeks after application of ammonium nitrate fertilizer. This suggests that the volatilization of ammonium nitrate fertilizer is rapid, and an important source of NH3. Because of the characteristic times for the loss mechanisms, synoptic time-scale phenomena may play an important role in determining the tropospheric distribution of NH3 concentrations.

Levine, J. S.; Hoell, J. M.; Augustsson, T. R.

1980-01-01

334

Vertically supported two-directional comb drive  

NASA Astrophysics Data System (ADS)

A vertically supported comb drive with the feasibility of actuation in two perpendicular directions utilizing electrostatic force from interdigitated comb-shape electrodes has been demonstrated. The prototype microstructures are made of 2 µm thick polysilicon by a standard surface micromachining process. They are vertically lifted after the final sacrificial layer releasing process and are fixed on the substrate with the assistance of micro locking springs and micro hinges. The microstructures can vibrate in the directions either parallel or normal to the comb fingers, depending on the physical setups of the supporting structures and the polarity of driving electrodes. Experimentally, under 10 V dc bias voltage and 10 V ac peak-to-peak driving voltage in air, the prototype structure is found to resonate at the first fundamental mode of 6.8 kHz in the parallel direction. In the direction normal to the surface of the comb fingers, several bands of vibration movements have been observed between 500 Hz and 11.9 kHz due to the strong coupling between the two comb structures. As such, these microresonators using the vertically supported two-directional comb drive might find potential applications in the area of MEMS or MOEMS including optical systems on a chip. A portion of this paper was presented at the 12th International Conference on Solid-State Sensors and Actuators (Transducers '03), 8-12 June 2003, Boston, USA.

Lee, Ki Bang; Lin, Liwei

2005-08-01

335

[Vertical talus: current diagnostic and therapy options].  

PubMed

Congenital vertical talus is a rare condition which presents as an isolated deformity or in association with neuromuscular and/or genetic disorders. Pathoanatomically the deformity shows a dislocated talonavicular and subtalar joint. The etiology and pathogenesis are still not finally determined although in some cases a genetic basis has been identified. The clinical picture is that of a flat, convex longitudinal arch with abduction and dorsiflexion of the forefoot and an elevated heel. Clinical diagnosis is confirmed by plain radiographic imaging. Congenital vertical talus should not be confused with other deformities of the foot, such as congenital oblique talus, flexible flat feet or pes calcaneus. The object of treatment of congenital vertical talus is to restore a normal anatomical relationship between the talus, navicular and calcaneus to obtain a pain-free foot. Major reconstructive surgery has been reported to be effective but is associated with substantial complications. Good early results of a modified non-operative treatment using serial manipulation, cast treatment and minimally invasive surgery may change therapeutic concepts. PMID:23685500

Arbab, D; Rath, B; Quack, V; Lüring, C; Tingart, M

2013-06-01

336

Lunar and Vertical Distribution of Myctophidae  

NASA Astrophysics Data System (ADS)

The Myctophidae are the most numerous of the mesopelagic fishes in all oceans. Daily vertical migrations which connected with nutrition and energy exchange, are charac- teristic feature of the myctophids behavior. Myctophidae in main during the nighttime basic feed. There are two ecological groups of Myctophidae on the type of vertical migrations. (Some scientists select the third intermediate group). Superficial (nyc- toepipelagic) myctophids are species, which during the nighttime arrive at surface of water. Layer myctophids are fishes, which are located in the main pycnocline (thermo- and halocline) and enter into composition of fauna of sound scattering layers (SSL) during the nighttime. However lunar light is hardly influenced on the upper bound of myctophids localization during the night. Agrees Barham (1970) all Myctophidae are divided on two morphoecological types: active and inactive. These types differ on morphology, on a response on light, under the contents of lipids into organism. To the first type concern all superficial Myctophidae and majority of myctophids of the night zone of pycnocline, including the most numerous genus - Diaphus. To an inactive type concern myctophids of the second genus on number of species from the family - Lam- panyctus. Superficial Myctophidae do not achieve the surfaces of water for want of vertical migrations for want of maximum and intensive lunar light. They are located in SSL. Inactive layer myctophids are in this case located deeper than main SSL. Lunar light practically does not influence on remaining active layer Myctophidae.

Tsarin, S.

337

Heat transfer in vertically aligned phase change energy storage systems  

SciTech Connect

Convection effects on heat transfer are analyzed in low temperature and vertically aligned phase change energy storage systems. This is performed by detailed temperature measurements in the phase change material (PCM) in eighteen locations forming a grid of six radial and three axial positions. The system constitutes a double pipe configuration, where commercial grade paraffin wax is stored in the annular space between the two pipes and water flows inside the inner pipe. Vertical alignment of the system allowed for reverse of the flow direction of the heat transfer fluid (HTF), which is water. Therefore, the PCM is heated from the bottom for HTF flow from bottom to top and from the top as the HTF flow direction is reversed. For the former case, natural convection affects the melting process. Collected data are used to study variations in the transient temperature distribution at axial and radial positions as well as for the two-dimensional temperature field. The data are used to calculate the PCM heat transfer coefficient and to develop correlations for the melting Fourier number. Results indicate that the PCM heat transfer coefficient is higher for the case of PCM heating from bottom to top. Nusselt number correlations are developed as a function of Rayleigh, Stefan, and Fourier numbers for the HTF flow from bottom to top and as a function of Stefan and Fourier numbers for HTF flow from top to bottom. The enhancement ratio for heat transfer caused by natural convection increases and then levels off as the inlet temperature of the HTF is increased.

El-Dessouky, H.T.; Bouhamra, W.S.; Ettouney, H.M.; Akbar, M. [Kuwait Univ., Safat (Kuwait). Dept. of Chemical Engineering

1999-05-01

338

Aerosol particle vertical distributions and optical properties over Singapore  

NASA Astrophysics Data System (ADS)

As part of the Seven Southeast Asian Studies (7SEAS) program, an Aerosol Robotic Network (AERONET) sun photometer and a Micro-Pulse Lidar Network (MPLNET) instrument have been deployed at Singapore to study the regional aerosol environment of the Maritime Continent (MC). Using coincident AERONET Level 2.0 and MPLNET Level 2.0a data from 24 September 2009 to 31 March 2011, the seasonal variability of aerosol particle vertical distributions and optical properties is examined. On average, the bulk (˜65%) of aerosol extinction is found below 1.5 km with substantial aerosol loading (˜35%) above. Possibly due to the transition from El Niño to La Niña conditions and subsequent reduction in fire events, the MPLNET mean integrated aerosol extinction is observed to be the lowest for July-September 2010, which coincides with the typical MC biomass burning season. On the other hand, the highest mean integrated extinctions are derived for January-March 2010 and 2011, which can be attributed to off-season MC biomass burning smoke and anthropogenic pollution. The seasonal lidar ratios also show higher occurrences ?60 sr, which are indicative of biomass burning smoke, for October 2009-June 2010, but such occurrences decrease from July 2010 to March 2011 when La Niña conditions prevail. In addition, principal component analysis (PCA) identifies five primary aerosol vertical profile types over Singapore, i.e. strongly-capped/deep near-surface layer (SCD; 0-1.35 km), enhanced mid-level layer (EML; 1.35-2.4 km), enhanced upper-level layer (EUL; 2.4-3.525 km), deep contiguous layer (DCL; 3.525-4.95 km) and deep multi-layer (DML; >4.95 km). PCA also identifies an off-season MC biomass burning smoke event from 22 February to 8 March 2010, which is subsequently examined in detail.

Chew, Boon Ning; Campbell, James R.; Salinas, Santo V.; Chang, Chew Wai; Reid, Jeffrey S.; Welton, Ellsworth J.; Holben, Brent N.; Liew, Soo Chin

2013-11-01

339

Envera Variable Compression Ratio Engine  

SciTech Connect

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

Charles Mendler

2011-03-15

340

Going Up? The Pros and Cons of Vertical Expansion.  

ERIC Educational Resources Information Center

Describes the advantages and disadvantages of the vertical expansion of school buildings. Considers such factors as fire protection, compliance with the Americans with Disabilities Act, and cost. Discusses alternatives to vertical expansion. (PKP)

Myler, Patricia A.; Boggs, Richard C.

2002-01-01

341

On the Spectral Radius of Graphs with Cut Vertices  

Microsoft Academic Search

We study the spectral radius of graphs with n vertices and k cut vertices and describe the graph that has the maximal spectral radius in this class. We also discuss the limit point of the maximal spectral radius.

Abraham Berman; Xiao-dong Zhang

2001-01-01

342

Characterizing Vertical Mass Flux Profiles in Aeolian Saltation Systems  

E-print Network

This dissertation investigates characteristics of the vertical distributions of mass flux observed in field and laboratory experiments. Thirty vertical mass flux profiles were measured during a field experiment in Jericoacoara, Brazil from October...

Farrell, Eugene

2012-07-16

343

A Vertical Grid Module for Baroclinic Models of the Atmosphere  

SciTech Connect

The vertical grid of an atmospheric model assigns dynamic and thermo- dynamic variables to grid locations. The vertical coordinate is typically not height but one of a class of meteorological variables that vary with atmo- spheric conditions. The grid system is chosen to further numerical approx- imations of the boundary conditions so that the system is terrain following at the surface. Lagrangian vertical coordinates are useful in reducing the numerical errors from advection processes. That the choices will effect the numercial properties and accuracy is explored in this report. A MATLAB class for Lorentz vertical grids is described and applied to the vertical struc- ture equation and baroclinic atmospheric circulation. A generalized meteo- rolgoical coordinate system is developed which can support ?, isentropic ? vertical coordinate, or Lagrangian vertical coordinates. The vertical atmo- spheric column is a MATLAB class that includes the kinematic and ther- modynamic variables along with methods for computing geopoentials and terms relevant to a 3D baroclinc atmospheric model.

Drake, John B [ORNL

2008-04-01

344

Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Joint, Vertical Cross Bracing End Detail - Ceylon Covered Bridge, Limberlost Park, spanning Wabash River at County Road 900 South, Geneva, Adams County, IN

345

Estimation of cerebral surface area using vertical sectioning and magnetic resonance imaging: a stereological study.  

PubMed

Stereological techniques using isotropic uniform random and vertical uniform random sections have been used for surface area estimation. However, there are a few studies in which the surface area of the brain is estimated using the vertical section technique in a stereological approach. The objective of the current study was to apply the vertical section technique using cycloid test probes for estimation of cerebral surface area in magnetic resonance imaging (MRI). In this study, cerebral surface areas were estimated in a total of 13 young subjects (6 males, 7 females) who were free of any neurological symptoms and signs. The means (+/-S.D.) of the surface areas were 1619.92+/-140. 97 cm (2), 1625.69+/-147. 58 cm(2) and 1674.69+/-160. 60 cm(2) for 36, 18 and 12 vertical sections, respectively. The mean coefficient of error obtained by applying cycloid test lines that use a 2. 8-cm ratio of area associated with each cycloid was estimated at <7% for the three models. No significant difference was found for each of the 36, 18 and 12 vertical sections (p>0.05). In addition, the three models correlated well with each other. From these results, it is concluded that the vertical section technique is an unbiased, efficient and reliable method and is ideally suited to in vivo examination of MRI data for estimating the surface area of the brain. Hence, we suggest that estimation of surface area using MRI and stereology may be clinically relevant for assessing cortical atrophy as well as for investigating the structure and function of cerebral hemispheres. PMID:19914221

Acer, Niyazi; Cankaya, Mehmet Niyazi; I?çi, Oznur; Ba?, Orhan; Camurdano?lu, Mehmet; Turgut, Mehmet

2010-01-15

346

Vertical Transmission of Hepatitis C Virus: Systematic Review and Meta-analysis  

PubMed Central

Background.?We conducted a systematic review of estimates of hepatitis C virus (HCV) vertical transmission risk to update current estimates published more than a decade ago. Methods.?PubMed and Embase were searched and 109 articles were included. Pooled estimates of risk were generated for children born to HCV antibody–positive and viremic women, aged ?18 months, separately by maternal human immunodeficiency virus (HIV) coinfection. Results.?Meta-analysis of the risk of vertical HCV infection to children of HCV antibody–positive and RNA-positive women was 5.8% (95% confidence interval [CI], 4.2%–7.8%) for children of HIV-negative women and 10.8% (95% CI, 7.6%–15.2%) for children of HIV-positive women. The adjusted meta-regression model explained 51% of the between-study variation in the 25 included risk estimates. Maternal HIV coinfection was the most important determinant of vertical transmission risk (adjusted odds ratio, 2.56 [95% CI, 1.50–4.43]). Additional methodological (follow-up rate and definition of infection in children) and risk factors independently predicted HCV infection and need to be captured and reported by future studies of vertical transmission. Studies assessing the contribution of nonvertical exposures in early childhood to HCV prevalence among children at risk of vertical transmission are needed. Conclusions.?More than 1 in every 20 children delivered by HCV chronically infected women are infected, highlighting that vertical transmission likely constitutes the primary transmission route among children. These updated estimates are a basis for decision making in prioritization of research into risk-reducing measures, and inform case management in clinical settings, especially for HIV-positive women in reproductive age. PMID:24928290

Benova, Lenka; Mohamoud, Yousra A.; Calvert, Clara; Abu-Raddad, Laith J.

2014-01-01

347

Likelihood ratios for genome medicine.  

PubMed

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

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

2010-01-01

348

Likelihood ratios for genome medicine  

PubMed Central

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

2010-01-01

349

Charge-to-mass Ratio of Saltating Particles in Wind-Blown Sand  

PubMed Central

The electrification of sand particles plays an important role in aeolian events. In this paper, the charge-to-mass ratio vertical profiles of saltating particles in wind-blown sand were measured by a field experiments. By combining the results of field measurements with our previous wind-tunnel measurements, we discussed the factors affecting the charge-to-mass ratio of saltating particles. It reveals that the magnitude of the charge-to-mass ratio increases exponentially with height above the surface. In addition, the charge polarity of saltating particles depends on the relative size between saltating and creeping particles, and the magnitude of charge-to-mass ratio is determined by wind velocity and the relative size difference ratio between saltating and creeping particles. PMID:24998641

Bo, Tian-Li; Zhang, Huan; Zheng, Xiao-Jing

2014-01-01

350

Dense, vertical jet in stagnant homogeneous fluid  

E-print Network

with riser height = 24 in. (61 cm) - . - . . . . ~ ~ Plot of Z /D vs, densimetric Froude number for di ffePent H/d ratios, compared to Abraham' s predi cted val ues and Turner ' s experimental data . 23 Plot of Fr vs. H/D ratio for different dilution... plot of' 2 /D vs. densimetric Froude number for each H/ D ratio and compares the results with Turner's experimental data (13) and with Abraham's predicted va 1 ues (2) . The measured concentrations at the bottom of the tank are time-dependent, i. e...

Vergara, Ignacio

1977-01-01

351

Diel Vertical Migration Thresholds of Karenia brevis (Dinophyceae).  

EPA Science Inventory

Light and nutrient availability change throughout dinoflagellate diel vertical migration (DVM) and/or with subpopulation location in the water column along the west Florida shelf. Typically, the vertical depth of the shelf is greater than the distance a subpopulation can vertical...

352

The illustration of the horizontal-vertical illusion  

Microsoft Academic Search

Seventy-two Ss attempted to equate in length the horizontal and the vertical line in each of four figures. In one figure (C) the horizontal line was bisected by the vertical, in the second (D) the vertical was bisected by the horizontal, and in the other two (A and B) the lines did not intersect. The three predictions underlying the experiment

Frank W. Finger; David K. Spelt

1947-01-01

353

Adaptation of vertical eye alignment in relation to head tilt  

Microsoft Academic Search

Binocular visual feedback is used to continually calibrate binocular eye alignment so that the retinal images of the two eyes remain in correspondence. Past experiments have shown that vertical eye alignment (measured as vertical phoria) can be altered by training to disparities that vary as a function of orbital eye position. The present experiments demonstrate that vertical eye alignment can

James S. Maxwell; Clifton M. Schor

1996-01-01

354

Functionality Tuning in Vertically Aligned Nanocomposite Thin Films  

E-print Network

and LSMO:ZnO VAN thin films with a vertical strain of 0.13 % and 0.5 %, respectively. We demonstrate that LFMR can be tuned by column width and vertical strain in these VAN systems, i.e., smaller column width and larger vertical strain could result in a...

Chen, Aiping

2013-04-04

355

Recent refinements and increased capabilities in balloon vertical performance analysis  

Microsoft Academic Search

A balloon vertical performance analysis model named THERMTRAJ (THERMal TRAJectory) was developed in the late '70's. This model combines the vertical equation of motion with heat balance equations to predict the balloon altitude, vertical rate, skin and gas temperatures versus time. THERMTRAJ provided significant improvement in performance analysis capabilities, but suffers from inadequacies, e.g., 1) assumed spherical shape, with maximum

G. R. Conrad

1993-01-01

356

The nature and growth of vertical specialization in world trade  

Microsoft Academic Search

Dramatic changes are occurring in the nature of international trade. Production processes increasingly involve a sequential, vertical trading chain stretching across many countries, with each country specializing in particular stages of a good's production sequence. We document a key aspect of these vertical linkages--the use of imported inputs in producing goods that are exported -- which we call vertical specialization.

David L. Hummels; Jun Ishii; Kei-Mu Yi

1999-01-01

357

Patterned Growth of Vertically Aligned Organic Nanowire Waveguide Arrays  

E-print Network

Patterned Growth of Vertically Aligned Organic Nanowire Waveguide Arrays Yong Sheng Zhao,,§ Peng developed, much less has been done with organic nanowires. For example, ordered vertical ar- rays devices.17 20 How- ever, vertical growth of organic nanowires has been rarely reported.21,22 Site

Huang, Jiaxing

358

Regularization and finiteness of the Lorentzian LQG vertices  

E-print Network

We give an explicit form for the Lorentzian vertices recently introduced for possibly defining the dynamics of loop quantum gravity. As a result of so doing, a natural regularization of the vertices is suggested. The regularized vertices are then proven to be finite. An interpretation of the regularization in terms of a gauge-fixing is also given.

Jonathan Engle; Roberto Pereira

2009-04-02

359

Regularization and finiteness of the Lorentzian loop quantum gravity vertices  

SciTech Connect

We give an explicit form for the Lorentzian vertices recently introduced for possibly defining the dynamics of loop quantum gravity. As a result of doing so, a natural regularization of the vertices is suggested. The regularized vertices are then proven to be finite. An interpretation of the regularization in terms of a gauge fixing is also given.

Engle, Jonathan [MPI fuer Gravitationsphysik (Albert-Einstein-Institut), Am Muehlenberg 1, D-14476 Potsdam (Germany); CPT, CNRS Case 907, Universite de la Mediterranee, F-13288 Marseille (France); Pereira, Roberto [CPT, CNRS Case 907, Universite de la Mediterranee, F-13288 Marseille (France)

2009-04-15

360

Dopant-Enhanced Vertical Alignment of Negative Liquid Crystals  

E-print Network

Dopant-Enhanced Vertical Alignment of Negative Liquid Crystals Chien-Hui Wen Benjamin Wu Sebastian, Florida, USA A simple method for achieving high-contrast vertical alignment of high birefringence (Dn$0 tolane liquid crystal host, an excellent vertical alignment was obtained. This alignment is stable

Wu, Shin-Tson

361

Natural Convection of Liquid Metals in Vertical Cavities  

E-print Network

Natural Convection of Liquid Metals in Vertical Cavities F. Wolff Research Assistant C. Beckermann- vection heat transfer and fluid flow in vertical cavities filled with liquid metals. Experiments vertical walls show a variation reflecting the complicated flow patterns. The need for highly accurate

Beckermann, Christoph

362

Material layer control based on slag vertical mill's steady conditions  

Microsoft Academic Search

The slag grinding process is introduced. The basic control forms of vertical mill are presented by analyzing the dynamic characteristics of material layer in slag vertical mill. Simulation results show that, in steady conditions, self-tuned scaling factors fuzzy controller performs better than basic fuzzy controller in material layer control. Self-tuned scaling factors fuzzy controller was applied in one slag vertical

Zhao Liu; Xiaohong Wang

2011-01-01

363

Full vertical car observer design methodology for suspension control applications  

E-print Network

Full vertical car observer design methodology for suspension control applications L. Dugarda , O of an H-observer to estimate the state variables of the vertical car dynamics to be used for suspension- sidered model is a 7 DOF full-car vertical model subject to unknown ground disturbances whose effects

Paris-Sud XI, Université de

364

Clinical utility of likelihood ratios.  

PubMed

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

Gallagher, E J

1998-03-01

365

Effect of outboard vertical-fin position and orientation on the low-speed aerodynamic performance of highly swept wings. [supersonic cruise aircraft research  

NASA Technical Reports Server (NTRS)

A theoretical study was conducted to determine the potential low-speed performance improvements which can be achieved by altering the position and orientation of the outboard vertical fins of low-aspect-ratio highly swept wings. Results show that the magnitude of the performance improvements is solely a function of the span-load distribution. Both the vertical-fin-chordwise position and toe angle provided effective means for adjusting the overall span-load distribution.

Johnson, V. S.; Coe, P. L., Jr.

1979-01-01

366

Some Effects of Frequency on the Contribution of a Vertical Tail to the Free Aerodynamic Damping of a Model Oscillating in Yaw  

NASA Technical Reports Server (NTRS)

The damping in yaw and the directional stability of a model freely oscillating in yaw were measured tail-off and tail-on and compared with the values obtained by theoretical consideration of the unsteady lift associated with an oscillating vertical tail. A range of low frequencies comparable to those of the lateral motions of airplanes was covered. The analysis includes the effects of vertical-tail aspect ratio and the two-dimensional effects of compressibility.

Bird, John D; Fisher, Lewis R; Hubbard, Sadie M

1953-01-01

367

The Microtremor H/V Spectral Ratio and Lateral Heterogeneity  

NASA Astrophysics Data System (ADS)

The average cross correlation of the ground motion fluctuations due to microtremors at pairs of given receivers, in the frequency domain, is linked to the imaginary part of Green function for such locations. For a single recording point, the average autocorrelation measures energy density and the Green function side of the equation is proportional to the power injected into the medium by a unit harmonic load at that point. This is the pseudo reflection response of the site. The problem has been dealt with recently for a horizontal stack of layers over a half-space which seems to be appropriate to study cases when ground motion is horizontally isotropic. Horizontal-to-vertical (H/V) spectral ratios of microtremors have been traditionally interpreted as representing either directly the S wave amplification or the Rayleigh wave ellipticity for a horizontal stack of layers. However, based on the diffuse field theory the microtremor H/V spectral ratio corresponds to the square root of the ratio of the imaginary part of horizontal displacement for a horizontally applied unit harmonic load, Imag.[G11], to the imaginary part of vertical displacement for a vertically applied unit load, Imag.[G33]. Both the loads and receivers are at the free surface. Therefore, we can invert the underground structure below a site if we observe microtremors there by using theoretical point source solution. For a sufficiently flat, horizontal stack of layers underneath a site we can easily calculate the theoretical Green function for that 1-D model. On the other hand, for a laterally heterogeneous underground structure, the horizontal reflection responses are different and in order to interpret microtremor H/V spectral ratios a numerical approach is needed. We can use the 3-D Finite Difference Method or the Indirect Boundary Element Method to study a model of a laterally heterogeneous elastic layer over a half-space. As observational evidence of 3-D microtremor H/V spectral ratios, we show that significant directional dependency has been observed at a site in Uji campus, Kyoto University, Japan, where the bedrock depth is varying from east to west from 250m to 420m within 1 km. The observed microtremor NS/UD spectral ratios are quite stable and have only one peak at around 2 seconds. On the other hand, the EW/UD spectral ratios are not as stable and have two peaks for most of the time sections that we observed for a whole day. This directional dependence can be considered to be the result of 3-D surface geology. After preliminary 1-D analysis using a model with a horizontal stack of layers, we perform 3-D point source analysis to see directional dependence in the Green function similar to the observation.

Hirokawa, T.; Matsushima, S.; Kawase, H.; Sanchez-Sesma, F. J.; Pérez Gavilán, J. J.; Suarez, M.; Salinas, V.

2010-12-01

368

Strain-induced vertical self-organization of semiconductor quantum dots: A computational study  

SciTech Connect

Atomistic strain simulations based on the valence force field method are employed to study the vertical arrangements of semiconductor quantum dot (QD) multilayers. The effects of the QD shape, dimensions, and materials parameters are systematically investigated, varying independently the following parameters: spacer width H, QD lateral spacing D, base b, and height h, slope of the side facets, elastic properties of the dot and the substrate materials, and lattice mismatch between the dot and the substrate. The transition between vertically aligned and anti-aligned structures is found to be determined mainly by the ratios H/D and b/D, as well as by the strain anisotropy of the substrate and to a lesser extent of the QD. The dependence on the QD height h is significant only for steep side facets and large aspect ratios h/b, and the effects of the lattice mismatch strain and the bulk elastic moduli are found to be negligible. The comparison with experimental data shows an excellent agreement with the results from the simulations, demonstrating that the presented analysis results in precise theoretical predictions for the vertical self-organization regime in a wide range of QD materials systems.

Shtinkov, N., E-mail: nshtinkov@uottawa.ca [Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa (Ontario) K1N 6N5 (Canada)

2013-12-28

369

Comparison of Aerosol Classification from Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask  

NASA Astrophysics Data System (ADS)

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft has acquired large datasets of aerosol extinction (532nm), backscatter (532 and 1064nm), and depolarization (532 and 1064nm) profiles during 349 science flights in 19 field missions across North America since 2006. The extinction-to-backscatter ratio ("lidar ratio"), aerosol depolarization ratios, and backscatter color ratio measurements from HSRL-1 are scale-invariant parameters that depend on aerosol type but not concentration. These four aerosol intensive parameters are combined to qualitatively classify HSRL aerosol measurements into eight separate composition types. The classification methodology uses models formed from "training cases" with known aerosol type. The remaining measurements are then compared with these models using the Mahalanobis distance. Aerosol products from the CALIPSO satellite include aerosol type information as well, which is used as input to the CALIPSO aerosol retrieval. CALIPSO aerosol types are inferred using a mix of aerosol loading-dependent parameters, estimated aerosol depolarization, and location, altitude, and surface type information. The HSRL instrument flies beneath the CALIPSO satellite orbit track, presenting the opportunity for comparisons between the HSRL aerosol typing and the CALIPSO Vertical Feature Mask Aerosol Subtype product, giving insight into the performance of the CALIPSO aerosol type algorithm. We find that the aerosol classification from the two instruments frequently agree for marine aerosols and pure dust, and somewhat less frequently for pollution and smoke. In addition, the comparison suggests that the CALIPSO polluted dust type is overly inclusive, encompassing cases of dust combined with marine aerosol as well as cases without much evidence of dust. Qualitative classification of aerosol type combined with quantitative profile measurements of aerosol backscatter and extinction has many useful applications. The HSRL products are used to apportion AOT by type and vertical location in the column, and to characterize the frequency of cases where multiple types are present in the column. Resolving scenes with multiple types in the column is not possible with passive imaging radiometer and polarimeter measurements. The HSRL aerosol type also has higher resolution than the CALIPSO layer-wise product and provides insight into the performance of CALIPSO layer separation. Information about the vertical distribution of aerosol types is useful for estimating radiative forcing, understanding aerosol lifetime and transport, and assessing the predictions of transport models. CALIPSO has been a pathfinder, providing the first long-term global data set of aerosol vertical distribution. Based on our results, a future satellite lidar similar to CALIPSO, but with the addition of polarization sensitivity at 1064 nm and the HSRL technique at 532 nm, could provide a significant advance in characterizing the vertical distribution of aerosol.

Burton, S. P.; Ferrare, R. A.; Omar, A. H.; Hostetler, C. A.; Hair, J. W.; Rogers, R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.

2012-12-01

370

Isokinetic Hamstrings: Quadriceps Ratios in Intercollegiate Athletes.  

ERIC Educational Resources Information Center

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

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

2001-01-01

371

Compartment in vertical flow reactor for ferruginous mine water  

NASA Astrophysics Data System (ADS)

Mine effluents contain varying concentrations of ferrous ion along with other metal ions. Fe(II) that quickly oxidizes to form precipitates in the presence of oxygen under net alkaline or neutral conditions. Thus, passive treatment methods are designed for the mine water to reside in an open containment area so as to allow simultaneous oxidation and precipitation of Fe(II), such as in a lagoon or an oxidation pond. A vertical flow reactor (VFR) was also suggested to remediate ferruginous mine drainage passing down through an accreting bed of ochre. However, VFR has a limited operation time until the system begins to overflow. It was also demonstrated that two-compartment VFR has a longer operation time than single compartment VFR of same size. In this study, a mathematical model was developed as a part of efforts to explore the operation of VFR, showing dynamic changes in head differences, ochre depth and Fe(II)/Fe(III) concentration in the effluent flow. The analysis shows that Fe(II) oxidation and ochre formation should be balanced with permeability of ochre bed to maximize VFR operation time and minimize residual Fe(II) in the effluent. The model demonstrates that two compartment VFR can have a longer operation time than a single-compartment VFR and that an optimum compartment ratio exists that maximize VFR operation time. Accelerated Fe(II) oxidation significantly affects the optimum ratio of compartment area and reduced residual Fe(II) in the effluent. VFR operation time can be significantly prolonged by increasing the rate of ochre formation not by accelerated Fe(II) oxidation. Taken together, ochre forms largely in the first compartment while overflowed mine water with reduced iron contents is efficiently filtered in the second compartment. These results provide us a better understanding of VFR operation and optimum design criteria for maximum operation time in a two-compartment VFR. Rapid ochre accretion in the first compartment maintains constant hydraulic head to maximize flow passing down through the ochre bed. Filtration rate in the second compartment is also facilitated by thin ochre bed because of low residual Fe(II) in the overflow. Thus, compartment ratio also significantly affects the operation span of two-compartment VFR. Accelerated Fe(II) oxidation significantly affects the optimum ratio of compartment area and reduced residual Fe(II) in the effluent. VFR operation time can be significantly prolonged by increasing the rate of ochre formation not by accelerated Fe(II) oxidation.

Hur, Won; Cheong, Young-Wook; Yim, Gil-Jae; Ji, Sang-Woo; Hong, Ji-Hye

2014-05-01

372

Determination of vertical and horizontal wavelengths of gravity waves  

NASA Technical Reports Server (NTRS)

The determination of horizontal and vertical wavelengths of gravity waves obviously relies on measurement of wave parameters in horizontal and vertical directions. A very suitable parameter, measured fairly easily with MST radars, is the fluid velocity. Average velocities and superimposed turbulent fluctuations are much larger in the horizontal than in the vertical direction. Vertical and horizontal fluid velocities due to wave-like events are mostly about equal in magnitude. Vertical fluid velocities due to waves therefore can be more reliably detected than horizontal velocities. Estimates of gravity wave events using MST radar data are calculated and results are indicated.

Rottger, J.

1983-01-01

373

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

374

Lorentz ratio of quantum plasmas  

SciTech Connect

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

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

1994-06-01

375

Beaded Braids: Investigating Patterns & Ratios  

NSDL National Science Digital Library

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

Lawrence Hall of Science

2003-01-01

376

Advanced high area ratio nozzles  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

377

Advanced high area ratio nozzles  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

378

OH vertical column abundance - Tropical measurements  

NASA Technical Reports Server (NTRS)

Measurements of the vertical column abundance of atmospheric hydroxyl (OH) have been made during the period 1987-1989 at the National Weather Service (NWS) station at Moen, Truk, Federated States of Micronesia (7 deg N, 152 deg E). A total of 384 independent data sets was obtained. Tropical OH abundance levels average about 22 percent above corresponding mid-latitude values, with OH levels during late winter and early spring up to 50 percent above those observed at 40 deg N. Stratospheric wind and temperature data obtained from the daily NWS radiosonde data are examined for correlations with the OH results.

Burnett, Clyde R.; Minschwaner, Kenneth R.; Burnett, Elizabeth B.

1990-01-01

379

Long wavelength vertical cavity surface emitting laser  

DOEpatents

Selectively oxidized vertical cavity lasers emitting near 1300 nm using InGaAsN quantum wells are reported for the first time which operate continuous wave below, at and above room temperature. The lasers employ two n-type Al.sub.0.94 Ga.sub.0.06 As/GaAs distributed Bragg reflectors each with a selectively oxidized current aperture adjacent to the active region, and the top output mirror contains a tunnel junction to inject holes into the active region. Continuous wave single mode lasing is observed up to 55.degree. C.

Choquette, Kent D.; Klem, John F.

2005-08-16

380

Vertical Cable Seismic Survey for Hydrothermal Deposit  

NASA Astrophysics Data System (ADS)

The vertical cable seismic is one of the reflection seismic methods. It uses hydrophone arrays vertically moored from the seafloor to record acoustic waves generated by surface, deep-towed or ocean bottom sources. Analyzing the reflections from the sub-seabed, we could look into the subsurface structure. This type of survey is generally called VCS (Vertical Cable Seismic). Because VCS is an efficient high-resolution 3D seismic survey method for a spatially-bounded area, we proposed the method for the hydrothermal deposit survey tool development program that the Ministry of Education, Culture, Sports, Science and Technology (MEXT) started in 2009. We are now developing a VCS system, including not only data acquisition hardware but data processing and analysis technique. Our first experiment of VCS surveys has been carried out in Lake Biwa, JAPAN in November 2009 for a feasibility study. Prestack depth migration is applied to the 3D VCS data to obtain a high quality 3D depth volume. Based on the results from the feasibility study, we have developed two autonomous recording VCS systems. After we carried out a trial experiment in the actual ocean at a water depth of about 400m and we carried out the second VCS survey at Iheya Knoll with a deep-towed source. In this survey, we could establish the procedures for the deployment/recovery of the system and could examine the locations and the fluctuations of the vertical cables at a water depth of around 1000m. The acquired VCS data clearly shows the reflections from the sub-seafloor. Through the experiment, we could confirm that our VCS system works well even in the severe circumstances around the locations of seafloor hydrothermal deposits. We have, however, also confirmed that the uncertainty in the locations of the source and of the hydrophones could lower the quality of subsurface image. It is, therefore, strongly necessary to develop a total survey system that assures a accurate positioning and a deployment techniques. We have carried out two field surveys in FY2011. One is a 3D survey with a boomer for a high-resolution surface source and the other one for an actual field survey in the Izena Cauldron an active hydrothermal area in the Okinawa Trough. Through these surveys, the VCS will become a practical exploration tool for the exploration of seafloor hydrothermal deposits.

Asakawa, E.; Murakami, F.; Sekino, Y.; Okamoto, T.; Ishikawa, K.; Tsukahara, H.; Shimura, T.

2012-04-01

381

Radiation tolerance of vertical junction solar cells  

NASA Technical Reports Server (NTRS)

Extensive radiation testing of vertical junction (VJ) solar cells demonstrated a radiation tolerance better than both planar silicon cells and at least one type of (AlGa)As-GaAs cell. Due to tradeoffs between short circuit current and open circuit voltage, the end of life (10 to the 16th power 1 MeV electrons/sq cm) maximum power point is nearly independent of bulk resistivity between 2 and 10 ohm cm, increases slightly with increasing wafer thickness between 3 and 11 mils, and increases slightly with increasing groove depth between 1 and 3 mils.

Schelnine, A.; Wohlgemuth, J.

1980-01-01

382

Second breakdown of vertical power MOSFET's  

NASA Astrophysics Data System (ADS)

It is shown that a phenomenon of second breakdown similar to that in bipolar transistors can occur in vertical power MOSFET's. A model for the phenomenon of second breakdown involving the avalanche multiplication of the channel current, the parasitic bipolar transistor, and base resistance is proposed. After presenting the theory, this model is compared with experiments on four-terminal V-groove test devices in which the substrate can be accessed independently. Good agreement is achieved between calculated and measured boundaries of the safe operating area. The model should be applicable to DMOS devices as well.

Hu, C.; Chi, M.-H.

1982-08-01

383

Vertical Isolation for Photodiodes in CMOS Imagers  

NASA Technical Reports Server (NTRS)

In a proposed improvement in complementary metal oxide/semi conduct - or (CMOS) image detectors, two additional implants in each pixel would effect vertical isolation between the metal oxide/semiconductor field-effect transistors (MOSFETs) and the photodiode of the pixel. This improvement is expected to enable separate optimization of the designs of the photodiode and the MOSFETs so as to optimize their performances independently of each other. The purpose to be served by enabling this separate optimization is to eliminate or vastly reduce diffusion cross-talk, thereby increasing sensitivity, effective spatial resolution, and color fidelity while reducing noise.

Pain, Bedabrata

2008-01-01

384

Airglow response to vertically standing gravity waves  

NASA Technical Reports Server (NTRS)

There is currently much interest in fluctuations of airglow emissions caused by atmospheric gravity waves. The fluctuations of brightness tend to be found in phase (or occasionally in antiphase) with the fluctuations of measured temperature, whereas current theory tends to anticipate substantial phase differences. We suggest here that the discrepancy results from failure of the common theoretical assumption that the relevant gravity waves are dominated by a single upgoing component: that, instead, there is an accompanying downgoing component of comparable magnitude, produced by reflection. In the case of total reflection, simple, steady state chemistry and vertical viewing, the phase difference is necessarily zero (or 180 deg).

Hines, Colin O.; Tarasick, David W.

1994-01-01

385

Finite element analysis and design of large diameter flexible vertical pipes subjected to incremental compacted backfill loads and creep effects  

E-print Network

OF TABLES XV i i Table 1. "Datum Case" Structural Responses of Vertical Flexible HDPE Pipe Manhole Subjected to Complete Height Backfill Load . 2. Structural Responses of the Flexible HDPE Vertical Pipe of the Example Problem 3. Summary... plastic pipes are made either as smooth-wall or as profile-wall. The purpose of a profile wall (Fig. 2) is to achieve a higher degree of stiffness-to-weight ratio than that of a smooth pipe, Flexible pipes normally fail in deflection in contrast...

Hossain, Mohammad Kabir

1990-01-01

386

Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on(001) ceria  

DOE PAGESBeta

Growth of high-aspect ratio oriented tin oxide, SnO2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO2 deposit. Second, vertical SnO2nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 ?m long nano-rods with an average diameter of ?20 nm.

Solovyov, Vyacheslav F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Li-jun [Brookhaven National Lab. (BNL), Upton, NY (United States); Rupich, Martin W. [American Superconductor, Devens, MA (United States); Sathyamurthy, Srivatsan [American Superconductor, Devens, MA (United States); Li, Xiaoping [American Superconductor, Devens, MA (United States); Li, Qiang [Brookhaven National Lab. (BNL), Upton, NY (United States)

2014-12-01

387

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

388

The perception of body verticality (subjective postural vertical) in peripheral and central vestibular disorders.  

PubMed

The perception of body verticality (subjective postural vertical, SPV) was assessed in normal subjects and in patients with peripheral and central vestibular lesions and the data were compared with conventional neuro-otological assessments. Subjects were seated with eyes closed in a motorized gimbal which executed cycles of tilt at low constant speed (1.5 degrees s-1), both in the frontal (roll) and sagittal (pitch) planes. Subjects indicated with a joystick when they entered and left verticality, thus defining a sector of subjective uprightness in each plane. The mean angle of tilt (identifying a bias of the SPV) and the width of the sector (defining sensitivity of the SPV) were then determined. In normal subjects, the angle of the "verticality' sector was 5.9 degrees for pitch and roll. Patients with bilateral absence of vestibular function, patients with vertigo, i.e. acute unilateral lesions, benign paroxysmal positional vertigo (BPPV) and Ménière's disease, and patients with positionally modulated up-/downbeat nystagmus all had enlarged sectors (i.e. loss in sensitivity). Mean sector angle in these groups ranged from 7.8 to 11 degrees and the abnormality was present both in pitch and roll, regardless of the direction of nystagmus or body sway. Patients with chronic unilateral peripheral vestibular lesions and those with position-independent vertical nystagmus had normal sensitivities. No significant bias of the SPV was found in any patient group, not even those with acute unilateral vestibular lesions who had marked tilts of the subjective visual vertical (SVV). Complementary experiments in normal subjects tested under galvanic vestibular or roll-plane optokinetic stimulation also failed to show biases of the SPV. In contrast, a significant bias in the SPV could be induced in normal subjects by asymmetric cycles of gimbals tilt, presumably by proprioceptive adaptation. The following conclusions can be drawn. (i) The perception of body verticality whilst seated is mainly dependent on proprioceptive/contact cues but these are susceptible to tilt-mediated adaptation. (ii) Vestibular input improves the sensitivity of the SPV, even in vestibular disorders, as long as the abnormality is stable. (iii) There can be marked dissociation between vestibulo-motor (ocular and postural) phenomena and the perception of body verticality, and between the SPV and SVV. (iv) The postural sway asymmetries in patients with peripheral and central vestibular lesions, like those induced by galvanic or optokinetic stimulation in normal subjects, are not consequences of changes of the SPV. PMID:8931577

Bisdorff, A R; Wolsley, C J; Anastasopoulos, D; Bronstein, A M; Gresty, M A

1996-10-01

389

Mass Spectrometry in Jupiter's Atmosphere: Vertical Variation of Volatile Vapors  

NASA Astrophysics Data System (ADS)

The Galileo Probe made the first and only in situ measurements of composition in Jupiter's atmosphere, led by the Galileo Probe Mass Spectrometer, or GPMS [1]. The major contribution from this instrument was the measurement of abundances and isotope ratios of the noble gases, as well as the volatile gases CH4, NH3, H2O, and H2S [2,3]. These initial results were further refined by detailed laboratory calibrations for the noble gases [4] and the volatiles [5]. The probe measurements resulted in the first determination of the heavy element abundances (except carbon that was known previously) and He/H ratio, which provide critical constraints to models of the formation of Jupiter and the origin of its atmosphere [6,7]. The condensable volatiles, or CVs (ammonia, H2S, and water), increased with depth in the probe entry site. This vertical variation was observed at levels much deeper than the modeled cloud bases, as predicted by one-dimensional chemical equilibrium models. The discrepancy is due to the probe's entry into a dry region known as a 5-?m hot spot. The 5-?m hot spots are part of an atmospheric wave system that encircles Jupiter just north of the equator. Despite the anomalous meteorology, the bulk abundances of NH3 and H2S were measured by the probe, and found to be enriched with respect to solar composition (similarly to the non-condensable volatile CH4). The deepest water mixing ratio, however, was observed to be depleted relative to solar composition. We review an updated context for the CV vertical profiles measured by the GPMS, based on the latest results from remote sensing, simulation, and reinterpretation of Galileo Probe measurements. In particular, we find that (1) the bulk abundance of water in Jupiter's atmosphere must be greater than the subsolar abundance derived from the deepest GPMS measurements [8], and that (2) CV mixing ratios are controlled by a range of processes in addition to condensation of the ices NH3, NH4SH, and H2O [5-9]. Both bulk abundances and spatial variation of these species will be further constrained by the Juno mission, scheduled to arrive at Jupiter in 2016. References: [1] Niemann, H.B. et al. 1992, SSRv 60, 111-142 [2] Niemann, H.B. et al. 1996, Science 272, 846-849 [3] Niemann, H.B. et al. 1998, JGR 103, 22831-22845 [4] Mahaffy, P.R. et al. 2000, JGR 105, 15061-15071 [5] Wong, M.H. et al. 2004, Icarus 171, 153-170 [6] Atreya, S.K. et al., 1999, Planet. Space Sci. 47, 1243-1262 [7] Atreya, S.K. et al., 2003, Planet. Space Sci. 451, 105-112 [8] Wong, M.H. et al., 2008, in Reviews in Mineralogy and Geochemistry, vol. 68. Mineralogical Society of America, Chantilly, VA, pp. 219-246 [9] Wong, M.H., 2009, Icarus 199, 231-235

Wong, Michael H.; Atreya, Sushil K.; Mahaffy, Paul R.

2014-05-01

390

Cross-sectional study of the retinal nerve fiber layer thickness at 7 years after an acute episode of unilateral primary acute angle closure.  

PubMed

The purpose of this article is to investigate the long-term retinal nerve fiber layer (RNFL) status and determinants of RNFL thinning after an episode of unilateral primary acute angle closure (AAC). This cross-sectional study analyzed the medical records of consecutive patients with a single episode of unilateral AAC from 1999 to 2009 in Hong Kong. The peripapillary RNFL thickness was correlated with age, gender, presenting intraocular pressure (IOP), time to laser iridotomy, time to cataract extraction, follow-up duration, as well as the last IOP, vertical cup-to-disc ratio (CDR), and vision. The fellow uninvolved eye was used as a proxy comparison of RNFL loss in the attack eye. In 40 eligible patients, the mean age was 68.3 ± 8.7 years with a male-to-female ratio of 1:7. The mean presenting IOP was 49.2 ± 14.0 mm Hg and the time from presentation to laser iridotomy was 6.7 ± 6.9 days. Forty percent of subjects received a cataract extraction at 3.2 ± 2.9 years after the attack. The last IOP, CDR, and LogMAR vision were 16.0 ± 3.8 mm Hg, 0.6 ± 0.2, and 0.6 ± 0.6 LogMAR units, respectively, at 7.9 ± 2.4 years. The RNFL thickness in the attack eye (69.2 ± 19.1 ?m) was 25.2 ± 17.9% thinner than the fellow eye (93.0 ± 17.8 ?m) at 7.5 ± 2.9 years post-AAC. Using univariate analysis, the last vertical CDR (odds ratio [OR]?= 17.2, P = 0.049) and LogMAR visual acuity (VA) (OR = 6.6, P = 0.03) were the only significant predictors for RNFL thinning whereas none of the other covariates showed significant associations (P > 0.1). At 7.5 years following unilateral AAC, the RNFL thickness was 25% thinner than the fellow eye. CDR enlargement and poor VA were the only significant predictors for RNFL loss. PMID:25590844

Lee, Jacky W Y; Woo, Tiffany T Y; Yau, Gordon S K; Yip, Stan; Yick, Doris W F; Wong, Jasper; Wong, Raymond L M; Wong, Ian Y H

2015-01-01

391

Experimental gas-solid vertical transport  

NASA Astrophysics Data System (ADS)

Gas-solid transport in dilute and dense phase conveying is studied. A new experimental system for vertical pneumatic conveying incorporates a screw feeder for dilute transport and an L-valve for dense flow. For measuring solid volume fractions a novel method using an x-ray densitometer was developed. The pressure in the system was measured using a strip chart recorder (SCR) and a manometer. The solids flux was estimated by collecting the particles from the system for a known time. The porosity and pressure drop data in the fully developed region were translated into drag coefficients and friction factors. The drag coefficients are in reasonable agreement with literature values. The friction factors with the wall were sometimes negative, reflecting downward flow, as observed in two-dimensional studies. Four available hydrodynamic models for vertical pneumatic conveying were used to predict the porosity and the pressure for the experimental conditions. Experimental data for porosity and pressure agree well with theoretical predictions. However, the predictions from the relative velocity model were in the best agreement for pressure drop values.

Luo, Kuo Ming

1987-05-01

392

Thunderstorm vertical velocities estimated from satellite data  

NASA Technical Reports Server (NTRS)

Infrared geosynchronous satellite data with an interval of 5 min between images are used to estimate thunderstorm top ascent rates on two case study days. A mean vertical velocity of 3.4 m/sec for 23 clouds is calculated at a height of 8.7 km. This upward motion is representative of an area of approximately 10 km on a side. Thunderstorm mass flux of approximately 2 times 10 to the 8th power kg/sec is calculated, which compares favorably with previous estimates. There is a significant difference in the mean calculated vertical velocity between elements associated with severe weather reports (omega = 4.9 m/sec) and those with no such reports (2.4 m/sec). Calculations were made using a velocity profile for an axially symmetric jet to estimate the peak updraft velocity. For the largest observed omega value of 7.8 m/sec the calculation indicates a peak updraft of approximately 50 m/sec.

Adler, R. F.; Fenn, D. D.

1979-01-01

393

Vertical Slot Convection: A linear study  

SciTech Connect

The linear stability properties of fluid convection in a vertical slot were studied. We use a Fourier-Chebychev decomposition was used to set up the linear eigenvalue problems for the Vertical Slot Convection and Benard problems. The eigenvalues, neutral stability curves, and critical point values of the Grashof number, G, and the wavenumber were determined. Plots of the real and imaginary parts of the eigenvalues as functions of G and [alpha] are given for a wide range of the Prandtl number, Pr, and special note is made of the complex mode that becomes linearly unstable above Pr [approximately] 12.5. A discussion comparing different special cases facilitates the physical understanding of the VSC equations, especially the interaction of the shear-flow and buoyancy induced physics. Making use of the real and imaginary eigenvalues and the phase properties of the eigenmodes, the eigenmodes were characterized. One finds that the mode structure becomes progressively simpler with increasing Pr, with the greatest complexity in the mid ranges where the terms in the heat equation are of roughly the same size.

McAllister, A. (Tokyo Univ. (Japan)); Steinolfson, R. (Southwest Research Inst., San Antonio, TX (United States)); Tajima, T. (Texas Univ., Austin, TX (United States). Inst. for Fusion Studies)

1992-11-01

394

Vertical Slot Convection: A linear study  

SciTech Connect

The linear stability properties of fluid convection in a vertical slot were studied. We use a Fourier-Chebychev decomposition was used to set up the linear eigenvalue problems for the Vertical Slot Convection and Benard problems. The eigenvalues, neutral stability curves, and critical point values of the Grashof number, G, and the wavenumber were determined. Plots of the real and imaginary parts of the eigenvalues as functions of G and {alpha} are given for a wide range of the Prandtl number, Pr, and special note is made of the complex mode that becomes linearly unstable above Pr {approximately} 12.5. A discussion comparing different special cases facilitates the physical understanding of the VSC equations, especially the interaction of the shear-flow and buoyancy induced physics. Making use of the real and imaginary eigenvalues and the phase properties of the eigenmodes, the eigenmodes were characterized. One finds that the mode structure becomes progressively simpler with increasing Pr, with the greatest complexity in the mid ranges where the terms in the heat equation are of roughly the same size.

McAllister, A. [Tokyo Univ. (Japan); Steinolfson, R. [Southwest Research Inst., San Antonio, TX (United States); Tajima, T. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies

1992-11-01

395

Vertical Profiling of Air Pollution at RAPCD  

NASA Technical Reports Server (NTRS)

The interaction between local and regional pollution levels occurs at the interface of the Planetary Boundary Layer and the Free Troposphere. Measuring the vertical distribution of ozone, aerosols, and winds with high temporal and vertical resolution is essential to diagnose the nature of this interchange and ultimately for accurately forecasting ozone and aerosol pollution levels. The Regional Atmospheric Profiling Center for Discovery, RAPCD, was built and instrumented to address this critical issue. The ozone W DIAL lidar, Nd:YAG aerosol lidar, and 2.1 micron Doppler wind lidar, along with balloon- borne ECC ozonesondes form the core of the W C D instrumentation for addressing this problem. Instrumentation in the associated Mobile Integrated Profiling (MIPS) laboratory includes 91 5Mhz profiler, sodar, and ceilometer. The collocated Applied particle Optics and Radiometry (ApOR) laboratory hosts an FTIR along with MOUDI and optical particle counters. With MODELS-3 analysis by colleagues in the National Space Science and Technology Center on the UAH campus and the co- located National Weather Service Forecasting Office in Huntsville, AL we are developing a unique facility for advancing the state of the science of pollution forecasting.

Newchurch, Michael J.; Fuller, Kirk A.; Bowdle, David A.; Johnson, Steven; Knupp, Kevin; Gillani, Noor; Biazar, Arastoo; Mcnider, Richard T.; Burris, John

2004-01-01

396

High vertical resolution crosswell seismic imaging  

DOEpatents

A method for producing high vertical resolution seismic images from crosswell data is disclosed. In accordance with one aspect of the disclosure, a set of vertically spaced, generally horizontally extending continuous layers and associated nodes are defined within a region between two boreholes. The specific number of nodes is selected such that the value of a particular characteristic of the subterranean region at each of the nodes is one which can be determined from the seismic data. Once values are established at the nodes, values of the particular characteristic are assigned to positions between the node points of each layer based on the values at node within that layer and without regard to the values at node points within any other layer. A seismic map is produced using the node values and the assigned values therebetween. In accordance with another aspect of the disclosure, an approximate model of the region is established using direct arrival traveltime data. Thereafter, the approximate model is adjusted using reflected arrival data. In accordance with still another aspect of the disclosure, correction is provided for well deviation. An associated technique which provides improvements in ray tracing is also disclosed.

Lazaratos, Spyridon K. (Houston, TX)

1999-12-07

397

Control system for a vertical axis windmill  

DOEpatents

A vertical axis windmill having a rotating structure is provided with a series of articulated vertical blades whose positions are controlled to maintain a constant RPM for the rotating structure, when wind speed is sufficient. A microprocessor controller is used to process information on wind speed, wind direction and RPM of the rotating structure to develop an electrical signal for establishing blade position. The preferred embodiment of the invention, when connected to a utility grid, is designed to generate 40 kilowatts of power when exposed to a 20 mile per hour wind. The control system for the windmill includes electrical blade actuators that modulate the blades of the rotating structure. Blade modulation controls the blade angle of attack, which in turn controls the RPM of the rotor. In the preferred embodiment, the microprocessor controller provides the operation logic and control functions. A wind speed sensor provides inputs to start or stop the windmill, and a wind direction sensor is used to keep the blade flip region at 90.degree. and 270.degree. to the wind. The control system is designed to maintain constant rotor RPM when wind speed is between 10 and 40 miles per hour.

Brulle, Robert V. (St. Louis County, MO)

1983-10-18

398

Effective Higgs vertices in the generic MSSM  

SciTech Connect

In this article we consider chirally enhanced corrections to Higgs vertices in the most general MSSM. We include the contributions stemming from bilinear terms, from the trilinear A terms, and from their nonholomorphic analogues, the A{sup '} terms, which couple squarks to the ''wrong'' Higgs field. We perform a consistent renormalization of the Higgs vertices beyond the decoupling limit (M{sub SUSY{yields}{infinity}}), using a purely diagrammatic approach. The cancellation of the different contributions in and beyond the decoupling limit is discussed and the possible size of decoupling effects which occur if the supersymmetry particles are not much heavier than the electroweak scale are examined. In the decoupling limit we recover the results obtained in the effective-field-theory approach. For the nonholomorphic A{sup '} terms we find the well known tan{beta} enhancement in the down sector similar to the one for terms proportional to {mu}. Because of the a priori generic flavor structure of these trilinear terms large flavor-changing neutral Higgs couplings can be induced. We also discover new tan{beta} enhanced contributions involving the usual holomorphic A terms, which were not discussed before in the literature. These corrections occur only if also flavor-diagonal nonholomorphic corrections to the Higgs couplings are present. This reflects the fact that the A terms, and also the chirality-changing self-energies, are physical quantities and cannot be absorbed into renormalization constants.

Crivellin, Andreas [Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, CH-3012 Bern (Switzerland)

2011-03-01

399

Modular low aspect ratio-high beta torsatron  

DOEpatents

A fusion reactor device in which the toroidal magnetic field and at least a portion of the poloidal magnetic field are provided by a single set of modular coils. The coils are arranged on the surface of a low aspect ratio toroid in planes having the cylindrical coordinate relationship .phi.=.phi..sub.i +kz where k is a constant equal to each coil's pitch and .phi..sub.i is the toroidal angle at which the i'th coil intersects the z=o plane. The device may be described as a modular, high beta torsation whose screw symmetry is pointed along the systems major (z) axis. The toroid defined by the modular coils preferably has a racetrack minor cross section. When vertical field coils and preferably a toroidal plasma current are provided for magnetic field surface closure within the toroid, a vacuum magnetic field of racetrack shaped minor cross section with improved stability and beta valves is obtained.

Sheffield, George V. (Hopewell, NJ); Furth, Harold P. (Princeton, NJ)

1984-02-07

400

Modular low-aspect-ratio high-beta torsatron  

DOEpatents

A fusion-reactor device is described which the toroidal magnetic field and at least a portion of the poloidal magnetic field are provided by a single set of modular coils. The coils are arranged on the surface of a low-aspect-ratio toroid in planed having the cylindrical coordinate relationship phi = phi/sub i/ + kz, where k is a constant equal to each coil's pitch and phi/sub i/ is the toroidal angle at which the i'th coil intersects the z = o plane. The toroid defined by the modular coils preferably has a race track minor cross section. When vertical field coils and, preferably, a toroidal plasma current are provided for magnetic-field-surface closure within the toroid, a vacuum magnetic field of racetrack-shaped minor cross section with improved stability and beta valves is obtained.

Sheffield, G.V.

1982-04-01

401

Numerical investigation of thermosolutal natural convection in a rectangular enclosure of an aspect ratio four with heat and solute sources  

NASA Astrophysics Data System (ADS)

A numerical study of double-diffusive natural convection in an enclosure with a partial vertical heat and mass sources for an aspect ratio Ar = 4 has been carried out. The influence of various dimensionless parameters (Rayleigh number, buoyancy ratio, source location, Lewis number, and source length) on the flow behavior are investigated. Correlations of average Nusselt and Sherwood numbers are obtained as function of two parameters (Ra, d) and (Le, d), respectively.

Oueslati, Fakher; Ben-Beya, Brahim; Lili, Taieb

2014-05-01

402

Economies of scale and vertical integration in the investor-owed electric utility industry  

SciTech Connect

This report analyzes the nature of costs in a vertically integrated electric utility. Findings provide new insights into the operations of the vertically integrated electric utility and supports earlier research on economics of scale and density; results also provide insights for policy makers dealing with electric industry restructuring issues such as competitive structure and mergers. Overall, results indicate that for most firms in the industry, average costs would not be reduced through expansion of generation, numbers of customers, or the delivery system. Evidently, the combination of benefits from large-scale technologies, managerial experience, coordination, or load diversity have been exhausted by the larger firms in the industry; however many firms would benefit from reducing their generation-to-sales ratio and by increasing sales to their existing customer base. Three cost models were used in the analysis.

Thompson, H.G. [Christensen Associates, Madison, WI (United States); Islam, M.; Rose, K.

1996-01-01

403

Electronic transport in individual, vertical, catalyst free GaN/AlN nanowires  

NASA Astrophysics Data System (ADS)

In the recent years, the advances in the THz technology, for example the development of the quantum cascade laser, promotes the possibility to use resonant tunneling diodes (RTD) to enhance such technologies. Coaxial m-plane AlN/GaN nanowire based resonant tunneling diode structures were formed by plasma assisted molecular beam epitaxy (MBE) using a two-step growth method that allows for control of vertical and lateral growth [1]. They are spontaneously formed MBE nanowires and they are integrated in Si (111). We discuss ongoing work on the electronic transport in these individual, vertical nanowires using two nanoprobes to contact the top of the nanowire and the substrate. The IV characteristics reveal a clear negative differential resistance (NDR) at room temperature (RT). The NDR was observed ˜ 4V with a peak-to-valley ratio as high as 10. [1] S.D. Carnevale et al., Nano Letters, 11, (2), 2011.

Marginean, Camelia; Carnevale, Santino; Phillips, Patrick; Kent, Thomas; Pelekhov, Denis; Mills, Michael; Myers, Roberto

2012-02-01

404

Transition between Atomic and Molecular Hydrogen in the Galaxy: Vertical Variation of the Molecular Fraction  

E-print Network

We derive radial and vertical distributions of HI and H2 gas densities in our Galaxy by using the terminal velocity method. We calculate the molecular fraction (f_mol) defined as the ratio of the molecular hydrogen to total hydrogen gas density at galactic longitude l= 33 to 64 deg and galactic latitude b=-2 to +2 deg. The thickness of the molecular dominant region f_mol > 0.8 is approximately constant (109 +/- 12 pc) at galactocentric distance R = 4.7 to 7.2 kpc. The molecular fraction decreases suddenly at a critical height from the galactic plane, below which the gas disk is almost totally molecular, while it is almost atomic beyond this height. We show that the vertical f_mol variation can be reproduced by a model which takes into account the phase transition between HI and H2 gases in the interstellar matter. Key words: Atomic Hydrogen --- the Galaxy --- Interstellar Matter --- Molecular Hydrogen

K. Imamura; Y. Sofue

1996-07-08

405

Edge technique Doppler lidar wind measurements with high vertical resolution.  

PubMed

We have developed a Doppler lidar system using the edge technique and have made atmospheric lidar wind measurements. Line-of-sight wind profiles with a vertical resolution of 22 m have a standard deviation of 0.40 m /s for a ten-shot average. Day and night lidar measurements of the vector wind have been made for altitudes from 200 to 2000 m. We validated the lidar measurements by comparing them with independent rawinsonde and pilot balloon measurements of wind speed and direction. Good agreement was obtained. The instrumental noise for these data is 0.11 m /s for a 500-shot average, which is in good agreement with the observed minimum value of the standard deviation for the atmospheric measurements. The average standard deviation over 30 mins varied from 1.16 to 0.25 m /s for day and night, respectively. High spatial and temporal resolution lidar profiles of line-of-sight winds clearly show wind shear and turbulent features at the 1 -2-m /s level with a high signal-to-noise ratio and demonstrate the potential of the edge-technique lidar for studying turbulent processes and atmospheric dynamics. PMID:18259439

Korb, C L; Gentry, B M; Li, S X

1997-08-20

406

Computational study of graphene-based vertical field effect transistor  

NASA Astrophysics Data System (ADS)

Poisson and drift-diffusion equations are solved in a three-dimensional device structure to simulate graphene-based vertical field effect transistors (GVFETs). Operation mechanisms of the GVFET with and without punched holes in the graphene source contact are presented and compared. The graphene-channel Schottky barrier can be modulated by gate electric field due to graphene's low density of states. For the graphene contact with punched holes, the contact barrier thinning and lowering around punched hole edge allow orders of magnitude higher tunneling current compared to the region away from the punched hole edge, which is responsible for significant performance improvement as already verified by experiments. Small hole size is preferred due to less electrostatic screening from channel inversion layer, which gives large electric field around the punched hole edge, thus, leading to a thinner and lower barrier. Bilayer and trilayer graphenes as the source contact degrade the performance improvement because stronger electrostatic screening leads to smaller contact barrier lowering and thinning. High punched hole area percentage improves current performance by allowing more gate electric field to modulate the graphene-channel barrier. Low effective mass channel material gives better on-off current ratio.

Chen, Wenchao; Rinzler, Andrew; Guo, Jing

2013-03-01

407

Comparison of aerodynamic models for Vertical Axis Wind Turbines  

NASA Astrophysics Data System (ADS)

Multi-megawatt Vertical Axis Wind Turbines (VAWTs) are experiencing an increased interest for floating offshore applications. However, VAWT development is hindered by the lack of fast, accurate and validated simulation models. This work compares six different numerical models for VAWTS: a multiple streamtube model, a double-multiple streamtube model, the actuator cylinder model, a 2D potential flow panel model, a 3D unsteady lifting line model, and a 2D conformal mapping unsteady vortex model. The comparison covers rotor configurations with two NACA0015 blades, for several tip speed ratios, rotor solidity and fixed pitch angle, included heavily loaded rotors, in inviscid flow. The results show that the streamtube models are inaccurate, and that correct predictions of rotor power and rotor thrust are an effect of error cancellation which only occurs at specific configurations. The other four models, which explicitly model the wake as a system of vorticity, show mostly differences due to the instantaneous or time averaged formulation of the loading and flow, for which further research is needed.

Simão Ferreira, C.; Aagaard Madsen, H.; Barone, M.; Roscher, B.; Deglaire, P.; Arduin, I.

2014-06-01

408

Steady flow past a vertical surface-piercing circular cylinder  

NASA Astrophysics Data System (ADS)

This paper describes experiments in which a vertical surface-piercing circular cylinder with a large draught was towed at steady speeds through water initially at rest. The cylinder diameter d was 210mm, and measurements were made of pressures around its circumference at elevations between 2.4d below still water level to 0.7d above, at Froude numbers (based on d) up to 1.67. The tests were carried out at a constant ratio of Reynolds number to Froude number of 2.79×105. The total resistance coefficient reached a maximum at a Froude number of about 1, when that part of the loading that can be attributed to the presence of the free surface was equivalent to the submerged form drag on a length of cylinder of about 0.9d. Measurements are also presented of the run-up on the front of the cylinder and of the depth of the depression at the back. Previous measurements by Hay (Flow about Semi-submerged Cylinders of Finite Length. Princeton University Report, Princeton, NJ, 1947) for the case of a cylinder with a submerged free end, and by Hsieh (Proc. Am. Soc. Civil Eng. 90 (1964) 161) of forces on cylinders standing on the floor of an open channel, are reanalysed. In most respects these results are found to be compatible with the present data for a cylinder of large draught.

Chaplin, J. R.; Teigen, P.

2003-09-01

409

VERTICAL DISTRIBUTION, DIEL VERTICAL MIGRATION, AND ABUNDANCE OF SOME MESOPELAGIC FISHES IN  

E-print Network

distribution. Populations of each myctophid species tended to be vertically stratified by age or size following sunset showed that three migratory species. the two migratory myctophids and E. pacifica, were and standing stock of myctophids were high-0.9 fish/m' and 0.37 g dry weightlm2· In 1973 we began a field study

410

Vertical GPS ground motion rates in the Euro-Mediterranean region: new evidence of vertical velocity gradients at different spatial scales along the Nubia-Eurasia plate boundary  

NASA Astrophysics Data System (ADS)

We use 2.5 to 14 years long position time-series from ~1000 continuous GPS stations to study vertical ground motions in the Euro-Mediterranean region and provide a first synoptic view of the vertical velocity field along the broad Nubia-Eurasia plate boundary. By estimating and removing common mode errors in position time-series from the results of a principal component analysis, we obtain a significant gain in the signal-to-noise ratio of the displacements data. Following the results of a maximum likelihood estimation analysis, which gives a mean spectral index ~-0.7, we adopt a power-law + white noise stochastic model in estimating the final vertical rates, and find 95% of the velocities within ×2 mm/yr in the study area, with uncertainties from filtered time-series ~40% smaller than from the unfiltered ones. We evaluate the contribute of the glacial isostatic adjustment (GIA) signal to the vertical velocity budget using two different global models, characterized by distinct rheological layering of the Earth's mantle and different descriptions of the time-history of the mass of continental ice sheets since the Last Glacial Maximum. The analysis carried out allows us to highlight, for the first time, the presence of statistically significant, and spatially coherent, velocity gradients where a higher density of stations is available. We find undulations of the vertical velocity field occurring at different spatial scales both in regions characterized by tectonic activity, like eastern Alps, Apennines and eastern Mediterranean, and regions characterized by low to null tectonic activity, like central Iberia and western Alps. Correcting the observed velocities for GIA, although the two models used predict different GIA velocities and patterns, doesn't change significantly the velocity gradients. A correlation between smooth vertical velocities and topographic features is apparent in many sectors of the study area. GIA and weathering processes cannot completely explain the measured rates, and a combination of active tectonics and deep-seated geodynamic processes must be used to explain our observations. Excluding areas where more localized processes are likely, or where subduction/delamination processes may be active, mantle dynamics is the most likely process, but regional mantle modeling is required for a better understanding.

Serpelloni, E.; Faccenna, C.; Spada, G.; Dong, D.; Williams, S. D.

2013-12-01

411

CALIPSO Observations of Transatlantic Dust: Vertical Stratification and Effect of Clouds  

NASA Technical Reports Server (NTRS)

CALIOP nighttime measurements of lidar backscatter, color and depolarization ratios during the summer of 2007 are used to study transatlantic dust properties downwind of Saharan sources, and to examine the interaction of clouds and dust. We discuss the following findings: (1) while lidar backscatter doesn't change much with altitude in the Saharan Air Layer (SAL), depolarization and color ratios both increase with altitude in the SAL; (2) lidar backscatter and color ratio increase as dust is transported westward in the SAL; (3) the vertical lapse rate of dust depolarization ratio increases within SAL as plumes move westward; (4) nearby clouds barely affect the backscatter and color ratio of dust volumes within SAL but not so below SAL. Finally, (5) the odds of CALIOP finding dust below SAL next to clouds are about 2/3 of those far away from clouds. This feature, together with an apparent increase in depolarization ratio near clouds, indicates that particles in some dusty volumes lose asphericity in the humid air near clouds, and cannot be identified by CALIPSO as dust.

Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Kalashnikova, Olga V.; Kostinski, Alexander B.

2012-01-01

412

CALIPSO Observations of Transatlantic Dust: Vertical Stratification and Effect of Clouds  

NASA Technical Reports Server (NTRS)

We use CALIOP nighttime measurements of lidar backscatter, color and depolarization ratios, as well as particulate retrievals during the summer of 2007 to study transatlantic dust properties downwind of Saharan sources, and to examine the influence of nearby clouds on dust. Our analysis suggests that (1) under clear skies, while lidar backscatter and color ratio do not change much with altitude and longitude in the Saharan Air Layer (SAL), depolarization ratio increases with altitude and decreases westward in the SAL (2) the vertical lapse rate of dust depolarization ratio, introduced here, increases within SAL as plumes move westward (3) nearby clouds barely affect the backscatter and color ratio of dust volumes within SAL but not so below SAL. Moreover, the presence of nearby clouds tends to decrease the depolarization of dust volumes within SAL. Finally, (4) the odds of CALIOP finding dust below SAL next to clouds are about of those far away from clouds. This feature, together with an apparent increase in depolarization ratio near clouds, indicates that particles in some dust volumes loose asphericity in the humid air near clouds, and cannot be identified by CALIPSO as dust.

Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Kalashnikova, Olga V.; Kostinski, Alexander B.

2014-01-01

413

On an infinite family of graphs with information ratio 2 - 1\\/k  

Microsoft Academic Search

In this paper we consider the secret sharing problem on special access structures with minimal qualified subsets of size two,\\u000a i.e. secret sharing on graphs. This means that the participants are the vertices of the graph and the qualified subsets are\\u000a the subsets of V(G) spanning at least one edge. The information ratio of a graph G is denoted by

László Csirmaz; Péter Ligeti

2009-01-01

414

Growth and electrical characterization of high-aspect-ratio carbon nanotube arrays  

Microsoft Academic Search

The remarkable properties of carbon nanotubes (CNTs) make them attractive for microelectronic applications, especially for interconnects and nanoscale devices. In this paper, we describe a microelectronics compatible process for growing high-aspect-ratio CNT arrays with application to vertical electrical interconnects. A lift-off process was used to pattern catalyst (Al2O3\\/Fe) islands to diameters of 13 or 20?m. After patterning, chemical vapor deposition

Lingbo Zhu; Jianwen Xu; Yonghao Xiu; Yangyang Sun; Dennis W. Hess; C. P. Wong

2006-01-01

415

Where have all the females gone? Male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) in alpine lakes  

NASA Astrophysics Data System (ADS)

In populations with both males and females sex-ratio is one of the driving forces of population dynamics. It influences fecundity, inbreeding and social interactions. Sex-ratio is affected by several biotic and abiotic factors, either by selective killing of one sex or by inducing migrations. In alpine lakes of Triglav National Park, Slovenia, an extremely male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) was regularly observed since 1992. We analysed population dynamics and sex-ratio of A. alpinus in three alpine lakes (Jezero v Ledvicah, Rjavo jezero and Zgornje Kriško jezero) from Triglav National Park in Slovenia. In addition to seasonal dynamics we also researched long-term changes in sex-ratio (in a period of 11 years from autumn samples) as a result of increased air-temperature, and zooplankton diurnal vertical migrations. Adults of both sexes were found to appear at the same time in the water collumn with males prevailing throughout the season. A similar trend was found in copepodites CV. The percent of adult females began increasing in late summer, when there were no more copepodites and recrutation from copepodites CV to adults stopped, while male mortality increased. All cohorts of A. alpinus were found to perform diurnal vertical migrations. Both adult and CV females remained close to the bottom during the day and migrated vertically during the night. Results of the long-term study show no changes in sex-ratio in autumn.

Žibrat, U.; Brancelj, A.

2009-04-01

416

FAME-C: Retrieval of cloud top pressure with vertically inhomogeneous cloud profiles  

NASA Astrophysics Data System (ADS)

A synergistic FAME-C (Freie Universität Berlin AATSR-MERIS Cloud Retrieval) algorithm is developed within the frame of the ESA CCI Cloud project. Within FAME-C the ratio of two MERIS measurements (the Oxygen-A absorption channel and a window channel) is used to retrieve cloud top pressure. In case of high, extended clouds the retrieved cloud top pressure is generally too high. This can be understood as an overestimation of extinction in upper cloud layers due to the assumption of vertical homogeneous clouds in the radiative transfer simulations. To include more realistic cloud vertical profiles, one year of data from the Cloud Profiling Radar (CPR) onboard CloudSat has been used to determine average normalized cloud vertical extinction profiles with a fixed pressure thickness for nine cloud types. The nine cloud types are based on the ISCCP COT-CTP classification table. The retrieved cloud top pressure, now using CloudSat cloud profiles in the forward model, is compared to CPR reflectivities as well as the retrieved cloud top pressure using vertically homogeneous cloud profiles. In the first number of cases under examination the overestimation of cloud top pressure, and therefore the bias, is reduced by a large amount when using CloudSat vertical cloud profiles. Another advantage is that no assumption about the cloud geometrical thickness has to be made in the new retrieval. It should be noted that comparisons between FAME-C products and A-train products can only be made at high latitudes where A-train and ENVISAT have overlapping overflights.

Henken, Cintia Carbajal; Lindstrot, Rasmus; Filipitsch, Florian; Walther, Andi; Preusker, Rene; Fischer, Jürgen

2013-05-01

417

Vertical and Interfacial Transport in Wetlands (Invited)  

NASA Astrophysics Data System (ADS)

The objective of this work is to understand the fluxes connecting the water column, substrate, and atmosphere in wetland environments. To do this, analytical, numerical, and laboratory models have been used to quantify the hydrodynamic contributions to vertical fluxes. A key question is whether the hydrodynamic transport can be modeled as a diffusivity, and, if so, what the vertical structure of this diffusivity is. This question will be addressed in a number of flow types and for a number of fluxes. The fluxes of interest are heat, sediment, dissolved gases (such as methane and oxygen) and other dissolved solutes (such as nutrients and pollutants). The flows of interest include: unidirectional current, reversing flow (under waves, seiches, and tides), wind-sheared surface flows, and thermal convection. Rain and bioturbation can be important, but are not considered in the modeling work discussed herein. Specifically, we will present results on gas transport at wind-sheared free surface, sediment transport in unidirectional flow, and heat transfer in an oscillating flow cause by a seiche. All three of these will be used to consider the question of appropriate analytical models for vertical transport. The analytic models considered here are all 1D models that assume homogeneity in the horizontal plane. The numerical models use finite element methods and resolve the flow around individual vegetation stems in an idealized geometry. Laboratory models discussed herein also use an idealized geometry. Vegetation is represented by an array of cylinders, whose geometry is modeled after Scirpus spp. wetlands in Northern California. The laboratory model is constructed in a way that allows optical access to the flow, even in dense vegetation and far from boundaries. This is accomplished by using fluoropolymer plastics to construct vegetation models. The optical access allows us to employ particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) to measure the velocity and scalar fields, respectively. To study sediment transport, an additional step is needed. Idealized sediment grains are manufactured, again using fluoropolymers. This allows the sediment and fluid phase to be resolved simultaneously, and the velocities of each to be determined independently of the other. The use of fluoropolymers means that the laboratory imaging techniques do not suffer from blockage during laser light delivery or during image capture by digital cameras. Cameras are paired and run in stereoscopic mode to allow three-dimensional velocities to be determined. This is important given the 3D nature of flow through vegetation. Current results from ongoing laboratory, field, and modeling efforts will be discussed, as well as the upcoming steps.

Variano, E. A.

2010-12-01

418

Low-speed test limit of V/STOL model located vertically off-center  

NASA Technical Reports Server (NTRS)

A vertically off-centered V/STOL model - a 2-ft-diam three-bladed aluminum propeller operating in a rotor mode - is tested in an 8 by 12 ft wind tunnel with and without ground plane along with an associated 3 by 4.5 ft test section insert. The objective was to assess the effect of the vertically off-centered model on the low-speed test limit. The aerodynamic data of the model at a constant negative angle of attack (-3 deg) are recorded at selected tunnel dynamic pressures to provide adequate data points to define the model lift variation with respect to the tip speed ratio. The adverse effect of the rotor low-speed test limit is observed in the form of lift change with respect to the tip speed ratio. A major conclusion is that for rotors tested with a ground plane or in the vicinity of the floor, the ratio of distance between floor and model to rotor radius defines the low-speed test limits.

Shindo, S.; Rae, W. H., Jr.

1978-01-01

419

Moving-base simulation evaluation of thrust margins for vertical landing for the NASA YAV-8B Harrier aircraft  

NASA Technical Reports Server (NTRS)

A simulation experiment was conducted on Ames Research Center's Vertical Motion Simulator to evaluate the thrust margin for vertical landing required for the YAV-8B Harrier. Two different levels of ground effect were employed, representing the aircraft with or without lift improvement devices installed. In addition, two different inlet temperature profiles were included to cover a wide range of hot gas ingestion. For each ground effect and hot gas ingestion variant, vertical landings were performed at successively heavier weights, with the pilot assessing the acceptability of the operation in each case. Results are presented as a function of hover weight ratio and a metric of the mean ground effect and ingestion that reflect the increase in thrust margin required to provide acceptable control of sink rate during the descent to touchdown with increasing suck down and hot gas ingestion.

Franklin, James A.; Stortz, Michael W.

1993-01-01

420

Integrated Vertical Bloch Line (VBL) memory  

NASA Technical Reports Server (NTRS)

Vertical Bloch Line (VBL) Memory is a recently conceived, integrated, solid state, block access, VLSI memory which offers the potential of 1 Gbit/sq cm areal storage density, data rates of hundreds of megabits/sec, and submillisecond average access time simultaneously at relatively low mass, volume, and power values when compared to alternative technologies. VBLs are micromagnetic structures within magnetic domain walls which can be manipulated using magnetic fields from integrated conductors. The presence or absence of BVL pairs are used to store binary information. At present, efforts are being directed at developing a single chip memory using 25 Mbit/sq cm technology in magnetic garnet material which integrates, at a single operating point, the writing, storage, reading, and amplification functions needed in a memory. The current design architecture, functional elements, and supercomputer simulation results are described which are used to assist the design process.

Katti, R. R.; Wu, J. C.; Stadler, H. L.

1991-01-01

421

Trends in the Vertical Distribution of Ozone  

NASA Technical Reports Server (NTRS)

Recent reanalyses of satellite, ground-based and balloon measurements allow updated estimates of trends in the vertical profile of ozone during 1980-96. The results show overall consistency between several independent measurement systems, particularly for northern hemisphere mid-latitudes where most ground-based measurements are made. Combined trend estimates over these latitudes show statistically significant negative trends at all altitudes between 10 and 45 km, with two local maxima: -7.4 +/- 2.0%/decade at 40 km and -7.6 +/- 4.6%/decade at 15 km altitude. There is a strong seasonal variation in trends over northern mid-latitudes in the altitude range of 10- 18 km. The profile trends are in quantitative agreement with independently measured trends in column ozone.

Randel, William J.; Stolarski, Richard S.; Cunnold, Derek M.; Logan, Jennifer A.; Newchurch, M. J.

1998-01-01

422

Vertical Oscillations of Fluid and Stellar Disks  

E-print Network

A satellite galaxy or dark matter subhalo that passes through a stellar disk may excite coherent oscillations in the disk perpendicular to its plane. We determine the properties of these modes for various self-gravitating plane symmetric systems (Spitzer sheets) using the matrix method of Kalnajs. In particular, we find an infinite series of modes for the case of a barotropic fluid. In general, for a collisionless system, there is a double series of modes, which include normal modes and/or Landau-damped oscillations depending on the phase space distribution function of the stars. Even Landau-damped oscillations may decay slowly enough to persist for several hundred Myr. We discuss the implications of these results for the recently discovered vertical perturbations in the kinematics of solar neighborhood stars and for broader questions surrounding secular phenomena such as spiral structure in disk galaxies.

Widrow, Lawrence M

2015-01-01

423

Membranes of vertically aligned superlong carbon nanotubes.  

PubMed

In the present work, we have developed a simple but effective method to prepare superlong vertically aligned carbon nanotubes (SLVA-CNT) and epoxy composite membranes, and we have demonstrated that various liquids, including water, hexane, and dodecane, can effectively pass through the SLVA-CNT membranes. These results were confirmed by molecular dynamics simulations. While the mechanical densification was used to further enhance the flow transport through the SLVA-CNT membranes, we developed in this study a magnetic-nanoparticle switching system to turn on and off the flow through the nanotube membrane by simply applying an alternating voltage. The methodologies developed in this study should have a significant implication to the development of various smart membranes for advanced intelligent systems. PMID:21657212

Du, Feng; Qu, Liangti; Xia, Zhenhai; Feng, Lianfang; Dai, Liming

2011-07-01

424

Vertical root fracture: prevalence, etiology, and diagnosis.  

PubMed

A vertical root fracture (VRF) is a frustrating complication that may occur following root canal treatment, and in almost every case leads to the extraction of the affected tooth. This type of fracture is usually diagnosed by secondary symptoms that develop some time after primary treatment, often when prosthodontic restoration has already been completed. The fracture line itself is often not directly visible, and therefore clinical and radiographic signs and symptoms indicate the diagnosis indirectly. Knowledge of the condition and pathogenesis of VRF is required in order to avoid hopeless trials of periodontal and/or endodontic therapy. Several etiologic factors are discussed that make teeth susceptible to VRF, such as the loss of substance due to restorative and endodontic therapy and stress factors associated with root canal debridement, and filling. PMID:23757466

Haueisen, Helga; Gärtner, Kathrin; Kaiser, Lea; Trohorsch, Dominik; Heidemann, Detlef

2013-07-01

425

Opportunity's Surroundings After Sol 1820 Drive (Vertical)  

NASA Technical Reports Server (NTRS)

NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009).

This view is presented as a vertical projection with geometric seam correction. North is at the top.

The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

2009-01-01

426

Vertical integration and optimal reimbursement policy  

PubMed Central

Health care providers may vertically integrate not only to facilitate coordination of care, but also for strategic reasons that may not be in patients’ best interests. Optimal Medicare reimbursement policy depends upon the extent to which each of these explanations is correct. To investigate, we compare the consequences of the 1997 adoption of prospective payment for skilled nursing facilities (SNF PPS) in geographic areas with high versus low levels of hospital/SNF integration. We find that SNF PPS decreased spending more in high integration areas, with no measurable consequences for patient health outcomes. Our findings suggest that integrated providers should face higher-powered reimbursement incentives, i.e., less cost-sharing. More generally, we conclude that purchasers of health services (and other services subject to agency problems) should consider the organizational form of their suppliers when choosing a reimbursement mechanism. PMID:21850551

Afendulis, Christopher C.

2011-01-01

427

Development of Vertical Cable Seismic System (2)  

NASA Astrophysics Data System (ADS)

The vertical cable seismic is one of the reflection seismic methods. It uses hydrophone arrays vertically moored from the seafloor to record acoustic waves generated by surface, deep-towed or ocean bottom sources. Analyzing the reflections from the sub-seabed, we could look into the subsurface structure. This type of survey is generally called VCS (Vertical Cable Seismic). Because VCS is an efficient high-resolution 3D seismic survey method for a spatially-bounded area, we proposed the method for the hydrothermal deposit survey tool development program that the Ministry of Education, Culture, Sports, Science and Technology (MEXT) started in 2009. We are now developing a VCS system, including not only data acquisition hardware but data processing and analysis technique. Our first experiment of VCS surveys has been carried out in Lake Biwa, JAPAN in November 2009 for a feasibility study. Prestack depth migration is applied to the 3D VCS data to obtain a high quality 3D depth volume. Based on the results from the feasibility study, we have developed two autonomous recording VCS systems. After we carried out a trial experiment in the actual ocean at a water depth of about 400m and we carried out the second VCS survey at Iheya Knoll with a deep-towed source. In this survey, we could establish the procedures for the deployment/recovery of the system and could examine the locations and the fluctuations of the vertical cables at a water depth of around 1000m. The acquired VCS data clearly shows the reflections from the sub-seafloor. Through the experiment, we could confirm that our VCS system works well even in the severe circumstances around the locations of seafloor hydrothermal deposits. We have carried out two field surveys in 2011. One is a 3D survey with a boomer for a high-resolution surface source and the other one for an actual field survey in the Izena Cauldron an active hydrothermal area in the Okinawa Trough. Through these surveys, we have confirmed that the uncertainty in the locations of the source and of the hydrophones in water could lower the quality of subsurface image. It is, therefore, strongly necessary to develop a total survey system that assures an accurate positioning and a deployment techniques. In case of shooting on sea surface, GPS navigation system are available, but in case of deep-towed source or ocean bottom source, the accuracy of shot position with SSBL/USBL is not sufficient for the very high-resolution imaging as requested for the SMS survey. We will incorporate the accurate LBL navigation systems with VCs. The LBL navigation system has been developed by IIS of the University of Tokyo. The error is estimated less than 10cm at the water depth of 3000m. Another approach is that the shot points can be calculated using the first break of the VCS after the VCS locations are estimated by slant-ranging from the sea surface. Our VCS system has been designed as a survey tool for hydrothermal deposit, but it will be also applicable for deep water site surveys or geohazard assessment such as active faults.

Asakawa, E.; Murakami, F.; Tsukahara, H.; Ishikawa, K.

2012-12-01

428

Dynamic soil pressures on rigid vertical walls  

SciTech Connect

A critical evaluation is made of the dynamic pressures and the associated forces induced by ground shaking on a rigid, straight, vertical wall retaining a semi-infinite, uniform viscoelastic layer of constant thickness. The effects of both harmonic and earthquake-induced excitations are examined. Simple approximate expressions for the responses of the system are developed, and comprehensive numerical data are presented which elucidate the effects and relative importance of the various parameters involved. These solutions are then compared with those obtained by use of a simple model proposed previously by Scott, and the accuracy of this model is assessed. Finally, two versions of an alternative model are proposed which better approximate the action of the system. In the first, the properties of the model are defined by frequency-dependent parameters, whereas in the second, which is particularly helpful in analyses of transient response, they are represented by frequency-independent, constant parameters.

Veletsos, A.S.; Younan, A.H. [Rice Univ., Houston, TX (United States)

1992-12-01

429

White light interferometry for vertical artifact calibration  

NASA Astrophysics Data System (ADS)

In this paper we describe a traceable to the meter standard method to measure the height of an artifact used as a calibrator for observation instruments in nanotechnologies and nanosciences. The artifact is a grating specially manufactured so that its features (height, pitch, width, wall angles) are highly uniform across its area. A Linnik microscope designed for longitudinal (vertical) measurements using the principle of white light interferometry was used to determine the height of the grating. To insure the traceability of the measurements a laser source of known wavelength was used and the measurements obtained using white light were calibrated to it. The experimental data was statistically analyzed and the measurement precision was estimated to be in the range of nanometers. The data were compared with the results obtained using the TIC method with a Carl Zeiss microscope.

Damian, V.; Bojan, Mihaela; Sima, A.; Cristea, Dana; Dinescu, A.; Muller, Raluca

2008-03-01

430

Vertical axis wind turbine control strategy  

SciTech Connect

Early expensive in automatic operation of the Sandia 17-m vertical axis research wind turbine (VAWT) has demonstrated the need for a systematic study of control algorithms. To this end, a computer model has been developed that uses actual wind time series and turbine performance data to calculate the power produced by the Sandia 17-m VAWT operating in automatic control. The model has been used to investigate the influence of starting algorithms on annual energy production. The results indicate that, depending on turbine and local wind characteristics, a bad choice of a control algorithm can significantly reduce overall energy production. The model can be used to select control algorithms and threshold parameters that maximize long-term energy production. An attempt has been made to generalize these results from local site and turbine characteristics to obtain general guidelines for control algorithm design.

McNerney, G.M.

1981-08-01

431

Oceanography. Vertical mixing in the ocean.  

PubMed

The thermohaline circulation of the ocean results primarily from downwelling at sites in the Nordic and Labrador Seas and upwelling throughout the rest of the ocean. The latter is often described as being due to breaking internal waves. Here we reconcile the difference between theoretical and observed estimates of vertical mixing in the deep ocean by presenting a revised view of the thermohaline circulation, which allows for additional upwelling in the Southern Ocean and the separation of the North Atlantic Deep Water cell from the Antarctic Bottom Water cell. The changes also mean that much less wind and tidal energy needs to be dissipated in the deep ocean than was originally thought. PMID:11343103

Webb, D J; Suginohara, N

2001-01-01

432

Origami multistability: from single vertices to metasheets.  

PubMed

We show that the simplest building blocks of origami-based materials-rigid, degree-four vertices-are generically multistable. The existence of two distinct branches of folding motion emerging from the flat state suggests at least bistability, but we show how nonlinearities in the folding motions allow generic vertex geometries to have as many as five stable states. In special geometries with collinear folds and symmetry, more branches emerge leading to as many as six stable states. Tuning the fold energy parameters, we show how monostability is also possible. Finally, we show how to program the stability features of a single vertex into a periodic fold tessellation. The resulting metasheets provide a previously unanticipated functionality-tunable and switchable shape and size via multistability. PMID:25699454

Waitukaitis, Scott; Menaut, Rémi; Chen, Bryan Gin-Ge; van Hecke, Martin

2015-02-01

433

Variable mixture ratio performance through nitrogen augmentation  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

434

TRIGONOMETRY: COMPARING RATIO AND UNIT CIRCLE METHODS  

Microsoft Academic Search

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

Margaret Kendal; Kaye Stacey

435

Experimental gas-solid vertical transport  

SciTech Connect

This study was directed towards an enhanced fundamental understanding of gas-solid transport in dilute and dense phase conveying. A new experimental system for vertical pneumatic conveying incorporated a screw feeder for dilute transport and an L-valve for dense flow. For measuring solid volume fractions a novel method using an x-ray densitometer was developed. The pressure in the system was measured using a strip chart recorder (SCR) and a manometer. The solids flux was estimated by collecting the particles from the system for a known time. The porosity and pressure drop data in the fully developed region were translated into drag coefficients and friction factors. The drag coefficients are in a reasonable agreement with the well-known literature values for drag for a single sphere. The friction factors with the wall were sometimes negative, reflecting downward flow, as observed in two-dimensional studies. Four available hydrodynamic models for vertical pneumatic conveying were used to predict the porosity and the pressure for the experimental conditions. Experimental data for porosity and pressure agree well with the theoretical predictions. However, the predictions from the relative velocity model were in the best agreement for pressure drop values. Drift flux equations were also used to predict the porosities in the fully developed region. The computations from the drift flux model are in a reasonably good agreement with the experimental data. To study the two-dimensional flow behavior in the conveying line, an experimental technique was developed to measure radial porosities. These results showed that the solid volume fraction was higher near the wall than in the core region. This pattern was verified by taking high speed movies. The local porosities and the local fluxes obtained from ball probe measurements were used to compute local solid velocities. 85 refs., 101 figs., 6 tabs.

Luo, Kuo Ming

1987-05-01

436

Vertical gradients of mineral elements in Pinus sylvestris crown in alkalised soil.  

PubMed

Alkalisation of soil has been assumed to be the principal cause of changes in vertical gradients of nutrients in Pinus sylvestris crown. The long-term influence of alkaline dust pollution (pHH2O 12.3-12.6) emitted from a cement plant on the element composition of soil and needles of Scots pine in different canopy layers was studied. In the polluted area, the pH of soils was >7, and high amounts of Ca, K and Mg were measured in the upper layers of soil (0-30 cm), while the mobility and solubility of some contaminants have decreased, nutrition processes have become complicated, and imbalance of mineral composition of trees was revealed. Reduced N and increased K, Ca and Mg concentrations in needles were observed in the heavily polluted area. Vertical gradients of elements and their ratios in canopies varied depending on the alkalisation level of soil. Needles on the upper-crown shoots had higher concentrations of N, C, Ca and Mg and lower concentrations of P and K compared to the lower layer of the crown. In the unpolluted area, higher concentrations of N, P, K and Ca were found in lower-crown needles and of C and Mg in needles at the top of the canopy. The P/N ratio below 0.125 indicated P deficiency in pines. The ratios N/Ca, N/Mg and N/K had significantly decreased, while the ratios Ca/Mg, K/Mg and K/Ca had a tendency to increase in heavily polluted sample plots. Magnitude of changes of element ratios indicates on the disbalances of availability and translocation of nutrients in the crown of trees. PMID:19015943

Mandre, Malle

2009-12-01

437

Learning About Ratios: A Sandwich Study  

NSDL National Science Digital Library

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

Sheryl Weinberg

1999-01-16

438

Vertical semiconducting single-walled carbon nanotube Schottky diode  

NASA Astrophysics Data System (ADS)

This paper presents a vertical semiconducting single-walled carbon nanotube (sSWCNT)-based Schottky device. For the first time, the author successfully demonstrated a vertical s-SWCNT Schottky diode on an anodized aluminum oxide (AAO) template. In the vertical pores of an AAO template s-SWCNTs were vertically grown and aligned. The vertical growth of s-SWCNTs inside the pores was achieved by successfully isolating the catalyst at the bottom of the pores by using redeposition enabled angled ion milling. The ends of the grown s-SWCNTs were coated with palladium and titanium to form Schottky and Ohmic contacts, respectively. The I-V characteristics of the vertical s-SWCNT paths engaging the Schottky and Ohmic contacts well demonstrated Schottky diode rectification.

Jung, Sunghwan

2014-07-01

439

Three-dimensional Numerical Analysis on Blade Response of Vertical Axis Tidal Current Turbine Under Operational Condition  

SciTech Connect

Tidal power as a large-scale renewable source of energy has been receiving significant attention recently because of its advantages over the wind and other renewal energy sources. The technology used to harvest energy from tidal current is called a tidal current turbine. Though some of the principles of wind turbine design are applicable to tidal current turbines, the design of latter ones need additional considerations like cavitation damage, corrosion etc. for the long-term reliability of such turbines. Depending up on the orientation of axis, tidal current turbines can be classified as vertical axis turbines or horizontal axis turbines. Existing studies on the vertical axis tidal current turbine focus more on the hydrodynamic aspects of the turbine rather than the structural aspects. This paper summarizes our recent efforts to study the integrated hydrodynamic and structural aspects of the vertical axis tidal current turbines. After reviewing existing methods in modeling tidal current turbines, we developed a hybrid approach that combines discrete vortex method -finite element method that can simulate the integrated hydrodynamic and structural response of a vertical axis turbine. This hybrid method was initially employed to analyze a typical three-blade vertical axis turbine. The power coefficient was used to evaluate the hydrodynamic performance, and critical deflection was considered to evaluate the structural reliability. A sensitivity analysis was also conducted with various turbine height-to-radius ratios. The results indicate that both the power output and failure probability increase with the turbine height, suggesting a necessity for optimal design. An attempt to optimize a 3-blade vertical axis turbine design with hybrid method yielded a ratio of turbine height to radius (H/R) about 3.0 for reliable maximum power output.

Li, Ye; Karri, Naveen K.; Wang, Qi

2014-04-30

440

REPRODUCTION About sex ratio in pigs  

E-print Network

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

Paris-Sud XI, Université de

441

Spray Gun With Constant Mixing Ratio  

NASA Technical Reports Server (NTRS)

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

Simpson, William G.

1987-01-01

442

REPRODUCTION About sex ratio in pigs  

E-print Network

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

Paris-Sud XI, Université de

443

On detecting change in likelihood ratio ordering  

Microsoft Academic Search

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

C. Xiong; Hammou El Barmi

2002-01-01

444

Management Ratios 1. For Colleges & Universities.  

ERIC Educational Resources Information Center

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

Minter, John, Ed.

445

Three-Dimensional Polymer Constructs Exhibiting a Tunable Negative Poisson’s Ratio  

PubMed Central

Young’s modulus and Poisson’s ratio of a porous polymeric construct (scaffold) quantitatively describe how it supports and transmits external stresses to its surroundings. While Young’s modulus is always non-negative and highly tunable in magnitude, Poisson’s ratio can, indeed, take on negative values despite the fact that it is non-negative for virtually every naturally occurring and artificial material. In some applications, a construct having a tunable negative Poisson’s ratio (an auxetic construct) may be more suitable for supporting the external forces imposed upon it by its environment. Here, three-dimensional polyethylene glycol scaffolds with tunable negative Poisson’s ratios are fabricated. Digital micromirror device projection printing (DMD-PP) is used to print single-layer constructs composed of cellular structures (pores) with special geometries, arrangements, and deformation mechanisms. The presence of the unit-cellular structures tunes the magnitude and polarity (positive or negative) of Poisson’s ratio. Multilayer constructs are fabricated with DMD-PP by stacking the single-layer constructs with alternating layers of vertical connecting posts. The Poisson’s ratios of the single- and multilayer constructs are determined from strain experiments, which show (1) that the Poisson’s ratios of the constructs are accurately predicted by analytical deformation models and (2) that no slipping occurrs between layers in the multilayer constructs and the addition of new layers does not affect Poisson’s ratio. PMID:21841943

Fozdar, David Y.; Soman, Pranav; Lee, Jin Woo; Han, Li-Hsin; Chen, Shaochen

2011-01-01

446

Three-Dimensional Polymer Constructs Exhibiting a Tunable Negative Poisson's Ratio.  

PubMed

Young's modulus and Poisson's ratio of a porous polymeric construct (scaffold) quantitatively describe how it supports and transmits external stresses to its surroundings. While Young's modulus is always non-negative and highly tunable in magnitude, Poisson's ratio can, indeed, take on negative values despite the fact that it is non-negative for virtually every naturally occurring and artificial material. In some applications, a construct having a tunable negative Poisson's ratio (an auxetic construct) may be more suitable for supporting the external forces imposed upon it by its environment. Here, three-dimensional polyethylene glycol scaffolds with tunable negative Poisson's ratios are fabricated. Digital micromirror device projection printing (DMD-PP) is used to print single-layer constructs composed of cellular structures (pores) with special geometries, arrangements, and deformation mechanisms. The presence of the unit-cellular structures tunes the magnitude and polarity (positive or negative) of Poisson's ratio. Multilayer constructs are fabricated with DMD-PP by stacking the single-layer constructs with alternating layers of vertical connecting posts. The Poisson's ratios of the single- and multilayer constructs are determined from strain experiments, which show (1) that the Poisson's ratios of the constructs are accurately predicted by analytical deformation models and (2) that no slipping occurrs between layers in the multilayer constructs and the addition of new layers does not affect Poisson's ratio. PMID:21841943

Fozdar, David Y; Soman, Pranav; Lee, Jin Woo; Han, Li-Hsin; Chen, Shaochen

2011-07-22

447

Are vertical cosmic rays the most suitable to radio detection ?  

E-print Network

The electric field induced by extensive air showers generated by high energy cosmic rays is considered and, more specifically, its dependence on the shower incident angle. It is shown that for distances between the shower axis and the observation point larger than a few hundred meters, non-vertical showers produce larger fields than vertical ones. This may open up new prospects since, to some extent, the consideration of non-vertical showers modifies the scope of the radio-detection domain.

T. Gousset; O. Ravel; C. Roy

2004-02-18

448

Head-position-dependent Adaptation of Nonconcomitant Vertical Skew  

Microsoft Academic Search

Vertical phoria can be trained to vary with either head position or orbital eye position. The present experiments show that subjects can simultaneously adapt their eye-position-specific (nonconcomi- tant) vertical phorias in different directions at different head positions. Eye-position-dependent and head-position-dependent adaptive pathways, therefore, are not independent. Rather, the adaptation of vertical skew takes into account both eye and head position.

JAMES S. MAXWELL; CLIFTON M. SCHOR

449

Head-position-dependent Adaptation of Nonconcomitant Vertical Skew  

Microsoft Academic Search

Vertical phoria can be trained to vary with either head position or orbital eye position. The present experiments show that subjects can simultaneously adapt their eye-position-specific (nonconcomitant) vertical phorias in different directions at different head positions. Eye-position-dependent and head-position-dependent adaptive pathways, therefore, are not independent. Rather, the adaptation of vertical skew takes into account both eye and head position. In

JAMES S MAXWELL; CLIFTON M SCHOR

1997-01-01

450

Correction of neglected vertical talus deformity in an adult.  

PubMed

Congenital vertical talus is an uncommon foot deformity that is characterised by a fixed dorsal dislocation of the navicular on the talar head and neck. Left untreated, a congenital vertical talus causes significant long-term disability. We present a case of neglected vertical talus in a middle-aged woman who was successfully treated with resection of the talar head and tendon transfers. PMID:25694638

Lui, Tun Hing

2015-01-01

451

Average vertical and zonal F region plasma drifts over Jicamarca  

Microsoft Academic Search

The seasonal averages of the equatorial F region vertical and zonal plasma drifts are determined using extensive incoherent scatter radar observations from Jicamarca during 1968-1988. The late afternoon and nighttime vertical and zonal drifts are strongly dependent on the 10.7-cm solar flux. The authors show that the evening prereversal enhancement of vertical drifts increases linearly with solar flux during equinox

B.G. Fejer; R.F. Woodman

1991-01-01

452

High transmittance of a twisted-vertical aligned liquid crystal display  

NASA Astrophysics Data System (ADS)

A high transmittance continuum domain twisted-vertical alignment (CDTVA) liquid crystal display (LCD) without domain walls defect and complex fabrication process has been developed. The CDTVA mode has no optical schlieren pattern occurring in the TVA cell. The optimum conditions for liquid crystal phase retardation (?) and cell gap-to-helical pitch ratio (d/p) were studied using three-dimensional finite element simulation, which showed good agreement with the experimental results. The results indicate that the maximum transmittance of the proposed CDTVA cell is similar to that of the twisted nematic mode thin-film-transistor LCD. Thus, CDTVA cell has potential applications for wide-viewing angle LCDs.

Peng, Cheng-Chung; Hsu, Kuei-Chu; Wu, Jin-Jei; Fan, Shih-Hung; Lee, Hsin-Ta; Shen, Yuhren

2010-12-01

453

Past changes in the vertical distribution of ozone – Part 1: Measurement techniques, uncertainties and availability  

E-print Network

in the homogenization of ozone data records should improve the signal-to-noise ratio in the ozone time series making trend analyses results more robust. “SPARC Report No.1 – Trends in the vertical distribution of ozone” (SPARC, 1998) provided a comprehensive sum- mary... in order to provide high sensitivity and low noise. The ozone number density is commonly retrieved from the difference of the slopes of the logarithm of the lidar signals corrected for the background noise and saturation affecting large signals originating...

Hassler, B.; Petropavlovskikh, I.; Staehelin, J.; August, T.; Bhartia, P. K.; Clerbaux, C.; Degenstein, D.; Maziere, M. De; Dinelli, B. M.; Dudhia, A.; Dufour, G.; Frith, S. M.; Froidevaux, L.; Godin-Beekmann, S.; Granville, J.; Harris, N. R. P.; Hoppel, K.; Hubert, D.; Kasai, Y.; Kurylo, M. J.; Kyrola, E.; Lambert, J.-C.; Levelt, P. F.; McElroy, C. T.; McPeters, R. D.; Munro, R.; Nakajima, H.; Parrish, A.; Raspollini, P.; Remsberg, E. E.; Rosenlof, K. H.; Rozanov, A.; Sano, T.; Sasano, Y.; Shiotani, M.; Smit, H. G. J.; Stiller, G.; Tamminen, J.; Tarasick, D. W.; Urban, J.; van der A, R. J.; Veefkind, J. P.; Vigouroux, C.; von Clarmann, T.; von Savigny, C.; Walker, K. A.; Weber, M.; Wild, J.; Zawodny, J. M.

2014-05-21

454

Self-assembled metallic nanowire-based vertical organic field-effect transistor.  

PubMed

We report on in situ, self-assembly, solution-processing of metallic (Au/Ag) nanowire-based transparent electrodes integrated to vertical organic field-effect transistors (VOFETs). In the VOFET architecture, the nanowires' microstructure facilitates current modulation by the gate across the otherwise shielding sandwiched source electrode. We show N-type VOFETs operation with on/off ratio ?1 × 10(5) and high current density (>1 mA cm(-2) at VDS = 5 V). The integration of the device design and the transparent electrode deposition methods offers a potential route for all-solution processing-based, large-area, high-efficiency organic electronics. PMID:25602371

Ben-Sasson, Ariel J; Azulai, Daniel; Gilon, Hagit; Facchetti, Antonio; Markovich, Gil; Tessler, Nir

2015-02-01

455

Optimized model of oriented-line-target detection using vertical and horizontal filters  

NASA Astrophysics Data System (ADS)

A line-element target differing sufficiently in orientation from a background of line elements can be visually detected easily and quickly; orientation thresholds for such detection are lowest when the background elements are all vertical or all horizontal. A simple quantitative model of this performance was constructed from two classes of anisotropic filters, (2) nonlinear point transformation, and (3) estimation of a signal-to-noise ratio based on responses to images with and without a target. A Monte Carlo optimization procedure (simulated annealing) was used to determine the model parameter values required for providing an accurate description of psychophysical data on orientation increment thresholds.

Westland, Stephen; Foster, David H.

1995-08-01

456

Measurements of Aerosol Vertical Profiles and Optical Properties during INDOEX 1999 Using Micro-Pulse Lidars  

NASA Technical Reports Server (NTRS)

Micro-pulse lidar systems (MPL) were used to measure aerosol properties during the Indian Ocean Experiment (INDOEX) 1999 field phase. Measurements were made from two platforms: the NOAA ship RN Ronald H. Brown, and the Kaashidhoo Climate Observatory (KCO) in the Maldives. Sunphotometers were used to provide aerosol optical depths (AOD) needed to calibrate the MPL. This study focuses on the height distribution and optical properties (at 523 nm) of aerosols observed during the campaign. The height of the highest aerosols (top height) was calculated and found to be below 4 km for most of the cruise. The marine boundary layer (MBL) top was calculated and found to be less than 1 km. MPL results were combined with air mass trajectories, radiosonde profiles of temperature and humidity, and aerosol concentration and optical measurements. Humidity varied from approximately 80% near the surface to 50% near the top height during the entire cruise. The average value and standard deviation of aerosol optical parameters were determined for characteristic air mass regimes. Marine aerosols in the absence of any continental influence were found to have an AOD of 0.05 +/- 0.03, an extinction-to-backscatter ratio (S-ratio) of 33 +/- 6 sr, and peak extinction values around 0.05/km (near the MBL top). The marine results are shown to be in agreement with previously measured and expected values. Polluted marine areas over the Indian Ocean, influenced by continental aerosols, had AOD values in excess of 0.2, S-ratios well above 40 sr, and peak extinction values approximately 0.20/km (near the MBL top). The polluted marine results are shown to be similar to previously published values for continental aerosols. Comparisons between MPL derived extinction near the ship (75 m) and extinction calculated at ship-level using scattering measured by a nephelometer and absorption using a PSAP were conducted. The comparisons indicated that the MPL algorithm (using a constant S-ratio throughout the lower troposphere) calculates extinction near the surface in agreement with the ship-level measurements only when the MBL aerosols are well mixed with aerosols above. Finally, a review of the MPL extinction profiles showed that the model of aerosol vertical extinction developed during an earlier INDOEX field campaign (at the Maldives) did not correctly describe the true vertical distribution over the greater Indian Ocean region. Using the average extinction profile and AOD obtained during marine conditions, a new model of aerosol vertical extinction was determined for marine atmospheres over the Indian Ocean. A new model of aerosol vertical extinction for polluted marine atmospheres was also developed using the average extinction profile and AOD obtained during marine conditions influenced by continental aerosols.

Welton, Ellsworth J.; Voss, Kenneth J.; Quinn, Patricia K.; Flatau, Piotr J.; Markowicz, Krzysztof; Campbell, James R.; Spinhirne, James D.; Gordon, Howard R.; Johnson, James E.; Starr, David OC. (Technical Monitor)

2001-01-01

457

Optimization of an optical configuration in a vertical alignment liquid crystal cell for wide viewing angle.  

PubMed

We propose an optical structure for a vertical alignment (VA) liquid crystal (LC) cell with a wide viewing angle. The proposed LC cell consists of an A-plate and two C-plates for optical compensation. Optical compensation and optimization to eliminate off-axis light leakage in the entire visible wavelength range are performed on a Poincaré sphere using the Stokes vector and the Muller matrix method. After optimizing the wavelength dispersion of the retardation films that are used, we prove that the proposed VA LC cell can improve the viewing angle and contrast ratio by calculating optical characteristics, particularly in diagonal directions. PMID:19107171

Ji, Seung-Hoon; Hee Lee, Seung; Lee, Gi-Dong

2009-01-01

458

The ZH ratio Analysis of Global Seismic Data  

NASA Astrophysics Data System (ADS)

The ZH ratio, the ratio of vertical to horizontal component of the fundamental Rayleigh wave as a function of frequency, is an alternative approach to phase/group velocity analysis for constructing the S-wave velocity structure. In this study, teleseismic Rayleigh wave data for the frequency range between 0.004Hz to 0.04Hz is used to investigate the interior structure. We have analyzed most of the GEOSCOPE network data and some IRIS GSN stations using a technique developed by Tanimoto and Rivera (2007). Stable estimates of the ZH ratios were obtained for the frequency range for most stations. We have performed the inversion of the measured ZH ratios for the structure in the crust and mantle by using nonlinear iterative scheme. The depth sensitivity kernels for inversion are numerically calculated. Depth sensitivity of the lowest frequency extends to depths beyond 500 km but the sensitivity of the overall data for the frequency band extends down to about 300km. We found that an appropriate selection of an initial model, particularly the depth of Mohorovicic discontinuity, is important for this inversion. The inversion result depends on the initial model and turned out to be non-unique. We have constructed the initial model from the CRUST 2.0. Inversion with equal weighting to each data point tends to reduce variance of certain frequency range only. Therefore, we have developed a scheme to increase weighting to data points that do not fit well after the fifth iteration. This occurs more often for low frequency range, 0.004-0.007Hz. After fitting the lower frequency region, the low velocity zone around a depth of 100km is observed under some stations such as KIP (Kipapa, Hawaii) and ATD (Arta Cave, Djibouti). We have also carried out an analysis on the resolving power of data by examining the eigenvalues-eigenvectors of the least-squares problem. Unfortunately, the normal matrix usually has 1-2 very large eigenvalues, followed by much smaller eigenvalues. The third one is often an order of magnitude smaller. The largest eigenvalue is always dominated by an eigenfunction that has the peak at the surface. It indicates that the ZH ratio is sensitive to shallow structure but it has limited form in resolving power for underlying structure. We will report on the details on the resolving capabilities of the ZH ratios.

Yano, T.; Shikato, S.; Rivera, L.; Tanimoto, T.

2007-12-01

459

ROSA: A computer model for optical power ratio calculations  

NASA Astrophysics Data System (ADS)

The Ratio of Solid Angles (ROSA) computer code was developed as part of the crosbyton solar power project (CSPP) for calculation of optical power concentrations due to reflection from a spherical segment mirror. The CSPP is concerned with the development of a technology for producing electric power from steam generated by reflection of the Sun's rays from a fixed-mirror solar bowl onto a tracking receiver. The ROSA code gives optical power concentration ratio profiles at points along the receiver surface. The ROSA code is written for a spherical segment mirror and the rim angle of the mirror is an input variable. Orientation of the axis of symmetry of the bowl is specified in terms of a vertical-east-north coordinate system. Location of the Sun relative to this coordinate system is also an input variable. The code permits any convex surface of revolution as a receiver. This report consists of two parts, a technical reference manual and a user's guide. The reference manual provides the background material and derivations necessary for the implementation of the code. Computer listings for ROSA are also included in the reference manual. The user's guide contains an explanation of the input data for the program, special user supplied subroutine requirements, a discussion of the output data, sample output and graphs of sample concentration profiles.

Anderson, R. M.; Ford, W. T.

1984-07-01

460

Midrapidity Antiproton-to-Proton Ratio in pp Collisons root s=0.9 and 7 TeV Measured by the ALICE Experiment  

Microsoft Academic Search

The ratio of the yields of antiprotons to protons in pp collisions has been measured by the ALICE experiment at root s = 0.9 and 7 TeV during the initial running periods of the Large Hadron Collider. The measurement covers the transverse momentum interval 0.45 < p(t) < 1.05 GeV\\/c and rapidity vertical bar y vertical bar < 0.5. The

K. Aamodt; N. Abel; U. Abeysekara; A. A. Quintana; A. Abramyan; D. Adamova; M. M. Aggarwal; G. A. Rinella; A. G. Agocs; S. A. Salazar; Z. Ahammed; A. Ahmad; N. Ahmad; S. U. Ahn; R. Akimoto; A. Akindinov; D. Aleksandrov; B. Alessandro; R. A. Molina; A. Alici; E. A. Avina; J. Alme; T. Alt; V. Altini; S. Altinpinar; C. Andrei; A. Andronic; G. Anelli; V. Angelov; C. Anson; T. Anticic; F. Antinori; S. Antinori; K. Antipin; D. Antonczyk; P. Antonioli; A. Anzo; L. Aphecetche; S. A. Appelshauser; S. Arcelli; R. Arceo; A. Arend; N. Armesto; R. Arnaldi; T. Aronsson; I. C. Arsene; A. Asryan; A. Augustinus; R. Averbeck; T. C. Awes; J. Aysto; M. D. Azmi; S. Bablok; M. Bach; A. Badala; Y. W. Baek; S. Bagnasco; R. Bailhache; R. Bala; A. Baldisser; A. Baldit; J. Ban; R. Barbera; G. G. Barnafoldi; L. S. Barnby; V. Barret; J. Bartke; F. Barile; M. Basile; V. Basmanov; N. Bastid; B. Bathen; G. Batigne; B. Batyunya; C. Baumann; I. G. Bearden; B. Becker; I. Belikov; R. Bellwied; E. Belmont-Moreno; A. Belogianni; L. Benhabib; S. Beole; I. Berceanu; A. Bercuci; E. Berdermann; Y. Berdnikov; L. Betev; A. Bhasin; A. K. Bhati; L. Bianchi; N. Bianchi; C. Bianchin; J. Bielcik; J. Bielcikova; A. Bilandzic; L. Bimbot; E. Biolcati; A. Blanc; F. Blanco; D. Blau; C. Blume; M. Boccioli; N. Bock; A. Bogdanov; H. Boggild; M. Bogolyubsky; J. Bohm; L. Boldizsar; M. Bombara; C. Bombonati; M. Bondila; H. Borel; A. Borisov; C. Bortolin; S. Bose; L. Bosisio; F. Bossu; M. Botje; S. Bottger; G. Bourdaud; B. Boyer; M. Braun; P. Braun-Munzinger; L. Bravina; M. Bregant; T. Breitner; G. Bruckner; R. Brun; E. Bruna; G. E. Bruno; D. Budnikov; H. Buesching; P. Buncic; O. Busch; Z. Buthelezi; D. Caffarri; X. Cai; H. Caines; E. Calvo; E. Camacho; P. Camerini; M. Campbell; V. C. Roman; G. P. Capitani; G. C. Romeo; F. Carena; W. Carena; F. Carminati; A. C. Diaz; M. Caselle; J. C. Castellanos; J. F. C. Hernandez; V. Catanescu; E. Cattaruzza; C. Cavicchioli; P. Cerello; V. Chambert; B. Chang; S. Chapeland; A. Charpy; J. L. Charvet; S. Chattopadhyay; M. Cherney; C. Cheshkov; B. Cheynis; E. Chiavassa; V. C. Barroso; D. D. Chinellato; P. Chochula; K. Choi; M. Chojnacki; P. Christakoglou; C. H. Christensen; P. Christiansen; T. Chujo; F. Chuman; C. Cicalo; L. Cifarelli; F. Cindolo; J. Cleymans; O. Cobanoglu; J. P. Coffin; S. Coli; A. Colla; G. C. Balbastre; Z. C. del Valle; E. S. Conner; P. Constantin; G. Contin; J. G. Contreras; Y. C. Morales; T. M. Cormier; P. Cortese; I. C. Maldonado; M. R. Cosentino; F. Costa; M. E. Cotallo; E. Crescio; P. Crochet; E. Cuautle; L. Cunqueiro; J. Cussonneau; A. Dainese; H. H. Dalsgaard; A. Danu; I. Das; A. Dash; S. Dash; G. O. V. de Barros; A. de Caro; G. de Cataldo; J. de Cuveland; A. De Falco; M. De Gaspari; J. de Groot; D. De Gruttola; N. De Marco; S. De Pasquale; R. De Remigis; R. de Rooij; G. de Vaux; H. Delagrange; Y. Delgado; G. Dellacasa; A. Deloff; V. Demanov; E. Denes; A. Deppman; G. DErasmo; D. Derkach; A. Devaux; D. Di Bari; C. Di Giglio; S. Di Liberto; A. Di Mauro; P. Di Nezza; M. Dialinas; L. Diaz; R. Diaz; T. Dietel; R. Divia; O. Djuvsland; V. Dobretsov; A. Dobrin; T. Dobrowolski; B. Donigus; I. Dominguez; D. M. M. Don; O. Dordic; A. K. Dubey; J. Dubuisson; L. Ducroux; P. Dupieux; A. K. D. Majumdar; M. R. D. Majumdar; D. Elia; D. Emschermann; A. Enokizono; B. Espagnon; M. Estienne; S. Esumi; D. Evans; S. Evrard; G. Eyyubova; C. W. Fabjan; D. Fabris; J. Faivre; D. Falchieri; A. Fantoni; M. Fasel; O. Fateev; R. Fearick; A. Fedunov; D. Fehlker; V. Fekete; D. Felea; B. Fenton-Olsen; G. Feofilov; A. F. Tellez; E. G. Ferreiro; A. Ferretti; R. Ferretti; M. A. S. Figueredo; S. Filchagin; R. Fini; F. M. Fionda; E. M. Fiore; M. Floris; Z. Fodor; S. Foertsch; P. Foka; S. Fokin; F. Formenti; E. Fragiacomo; M. Fragkiadakis; U. Frankenfeld; A. Frolov; U. Fuchs; F. Furano; C. Furget; M. F. Girard; J. J. Gaardhoje; S. Gadrat; M. Gagliardi; A. Gago; M. Gallio; P. Ganoti; M. S. Ganti; C. Garabatos; C. G. Trapaga; J. Gebelein; R. Gemme; M. Germain; A. Gheata; M. Gheata; B. Ghidini; P. Ghosh; G. Giraudo; P. Giubellino; E. Gladysz-Dziadus; R. Glasow; P. Glassel; A. Glenn; R. G. Jimenez; H. G. Santos; L. H. Gonzalez-Trueba; P. Gonzalez-Zamora; S. Gorbunov; Y. Gorbunov; S. Gotovac; H. Gottschlag; V. Grabski; R. Grajcarek; A. Grelli; A. Grigoras; C. Grigoras; V. Grigoriev; A. Grigoryan; S. Grigoryan; B. Grinyov; N. Grion; P. Gros; J. F. Grosse-Oetringhaus; J. Y. Grossiord; R. Grosso; F. Guber; R. Guernane; C. Guerra; B. Guerzoni; K. Gulbrandsen; H. Gulkanyan; T. Gunji; A. Gupta; R. Gupta; H. A. Gustafsson; H. Gutbrod; O. Haaland; C. Hadjidakis; M. Haiduc; H. Hamagaki; G. Hamar; J. Hamblen; B. H. Han; J. W. Harris; M. Hartig; A. Harutyunyan; D. Hasch; D. Hasegan; D. Hatzifotiadou; A. Hayrapetyan; M. Heide; M. Heinz; H. Helstrup; A. Herghelegiu; C. Hernandez; G. H. Corral; N. Herrmann; K. F. Hetland

2010-01-01

461

TURBULENCE IN THE OUTER REGIONS OF PROTOPLANETARY DISKS. II. STRONG ACCRETION DRIVEN BY A VERTICAL MAGNETIC FIELD  

SciTech Connect

We carry out a series of local, vertically stratified shearing box simulations of protoplanetary disks that include ambipolar diffusion and a net vertical magnetic field. The ambipolar diffusion profiles we employ correspond to 30 AU and 100 AU in a minimum mass solar nebula (MMSN) disk model, which consists of a far-ultraviolet-ionized surface layer and low-ionization disk interior. These simulations serve as a follow-up to Simon et al., in which we found that without a net vertical field, the turbulent stresses that result from the magnetorotational instability (MRI) are too weak to account for observed accretion rates. The simulations in this work show a very strong dependence of the accretion stresses on the strength of the background vertical field; as the field strength increases, the stress amplitude increases. For a net vertical field strength (quantified by ?{sub 0}, the ratio of gas to magnetic pressure at the disk mid-plane) of ?{sub 0} = 10{sup 4} and ?{sub 0} = 10{sup 5}, we find accretion rates M-dot ?10{sup -8}-10{sup –7} M{sub ?} yr{sup –1}. These accretion rates agree with observational constraints, suggesting a vertical magnetic field strength of ?60-200 ?G and 10-30 ?G at 30 AU and 100 AU, respectively, in a MMSN disk. Furthermore, the stress has a non-negligible component due to a magnetic wind. For sufficiently strong vertical field strengths, MRI turbulence is quenched, and the flow becomes largely laminar, with accretion proceeding through large-scale correlations in the radial and toroidal field components as well as through the magnetic wind. In all simulations, the presence of a low-ionization region near the disk mid-plane, which we call the ambipolar damping zone, results in reduced stresses there.

Simon, Jacob B.; Armitage, Philip J.; Beckwith, Kris [JILA, University of Colorado and NIST, 440 UCB, Boulder, CO 80309-0440 (United States); Bai, Xue-Ning [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, MA 02138 (United States); Stone, James M., E-mail: jbsimon@jila.colorado.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2013-09-20

462

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

463

Modification of vertical OKN and vertical OKAN asymmetry in humans during parabolic flight.  

PubMed

Characteristics of human vertical optokinetic nystagmus (OKN) and afternystagmus (OKAN) were examined by ISCAN imaging system on the ground and on board NASA's KC-135 aircraft in a parabolic flight study. The aircraft produced alternating periods of micro-(ca. 10(-2) G) and hyper-(ca. 1.8 G) gravitoinertial forces. Each phase lasted approximately 20 to 25 s. As compared to the baseline data on the ground, there was a significant increase of downward OKN/OKAN, whereas the upward OKN/OKAN did not change significantly in either micro- or hyper-G. As a consequence, the asymmetry of vertical OKN/OKAN, normally seen on the ground, was lost. It is postulated that the increase of downward OKN/OKAN in non-1-G conditions was governed by two different mechanisms. In micro-G, the normal inhibition effect in 1 G on the downward eye movement mediated by otolith organ activity to vertical velocity storage was removed. In hyper-G, downward OKN/OKAN was facilitated by augmented otolith-ocular reflex because of increased gravitoinertial force, so as to produce enhanced compensatory downward eye movement. PMID:9057157

Wei, G; Lafortune-Kahane, S; Ireland, D; Jell, R

1997-01-01

464

TOTAL PHOSPHORUS REMOVAL FROM DOMESTIC WASTEWATER WITH CYPERUS ALTERNIFOLIUS IN VERTICAL-FLOW CONSTRUCTED WETLANDS AT THE MICROCOSM LEVEL  

Microsoft Academic Search

Vertical-flow constructed wetland (VFCW) is an effective alternative for removal of nutrients, heavy metals, and organic pollutants from wastewaters. This study investigated the uptake and removal of total phosphorus (TP) by Cyperus alternifolius from domestic wastewaters in the simulated VFCWs. The total of eight simulated VFCW treatments, including two different substrates, two different wet-to-dry ratios, and with and without C.

Li-Hua Cui; Xi-Zhen Zhu; Ying Ouyang; Yin Chen; Feng-Le Yang

2011-01-01

465

Natural convection heat transfer from a long heated vertical cylinder to an adjacent air gap of concentric and eccentric conditions  

Microsoft Academic Search

In this work, the natural convection heat transfer from a long vertical electrically heated cylinder to an adjacent air gap\\u000a is experimentally studied. The aspect and diameter ratios of the cylinder are 55.56 and 6.33, respectively. The experimental\\u000a measurements were obtained for a concentric condition and six eccentricities from 0.1 to 0.92 at five different heat fluxes.\\u000a The surface temperature

R. Hosseini; A. Rezania; M. Alipour; L. A. Rosendahl

2011-01-01

466

Balloon-borne observations of the development and vertical structure of the Antarctic ozone hole in 1986  

Microsoft Academic Search

The vertical distribution of ozone measured at McMurdo Station, Antarctica using balloon-borne sensors on 33 occasions during November 6, 1986 - August 25, 1986 is described. These observations suggest a highly structured cavity confined to the 12-20 km altitude region. In the 17-19 km altitude range, the ozone volume mixing ratio declined from about 2 ppm at the end of

D. J. Hofmann; J. W. Harder; S. R. Rolf; J. M. Rosen

1987-01-01

467

Vertical-axis wind turbine modeling and performance with axial-flux permanent magnet synchronous generator for battery charging applications  

Microsoft Academic Search

The modeling and simulation of a 1kW vertical-axis direct drive topology wind turbine are implemented. An axial flux permanent magnet synchronous generator with multi-pole is directly connected to the wind turbine shaft. The wind turbine system is controlled to operate at constant tip-speed ratio and hence maximizing the power extracted from the wind. For battery charging applications, a modified version

Ahmad M. Eid; Mazen Abdel-Salam; M. Tharwat Abdel-Rahman

2006-01-01

468

Monitoring the vertical structure of the Arctic polar vortex over northern Scandinavia during EASOE: Regular N2O profile observations  

Microsoft Academic Search

Different whole air samplers were flown on large balloons launched from Kiruna (67.9°N 21.1°E) in the period from 30 November 1991 until 20 March 1992. Thirteen vertical profiles of the N2O mixing ratio were obtained from the analyses of the stratospheric air samples collected at altitudes between about 10 km and 31 km. The series of profile observations illustrates the

Reimar Bauer; Andreas Engel; Herbert Franken; Erich Klein; Gerhard Kulessa; Cornelius Schiller; Ulrich Schmidt; Reinhard Borchers; Julia Lee

1994-01-01

469

Development of Vertical Cable Seismic System (3)  

NASA Astrophysics Data System (ADS)

The VCS (Vertical Cable Seismic) is one of the reflection seismic methods. It uses hydrophone arrays vertically moored from the seafloor to record acoustic waves generated by surface, deep-towed or ocean bottom sources. Analyzing the reflections from the sub-seabed, we could look into the subsurface structure. Because VCS is an efficient high-resolution 3D seismic survey method for a spatially-bounded area, we proposed the method for the hydrothermal deposit survey tool development program that the Ministry of Education, Culture, Sports, Science and Technology (MEXT) started in 2009. We are now developing a VCS system, including not only data acquisition hardware but data processing and analysis technique. We carried out several VCS surveys combining with surface towed source, deep towed source and ocean bottom source. The water depths of the survey are from 100m up to 2100m. The target of the survey includes not only hydrothermal deposit but oil and gas exploration. Through these experiments, our VCS data acquisition system has been completed. But the data processing techniques are still on the way. One of the most critical issues is the positioning in the water. The uncertainty in the positions of the source and of the hydrophones in water degraded the quality of subsurface image. GPS navigation system are available on sea surface, but in case of deep-towed source or ocean bottom source, the accuracy of shot position with SSBL/USBL is not sufficient for the very high-resolution imaging. We have developed another approach to determine the positions in water using the travel time data from the source to VCS hydrophones. In the data acquisition stage, we estimate the position of VCS location with slant ranging method from the sea surface. The deep-towed source or ocean bottom source is estimated by SSBL/USBL. The water velocity profile is measured by XCTD. After the data acquisition, we pick the first break times of the VCS recorded data. The estimated positions of shot points and receiver points in the field include the errors. We use these data as initial guesses, we invert iteratively shot and receiver positions to match the travel time data. After several iterations we could finally estimate the most probable positions. Integration of the constraint of VCS hydrophone positions, such as the spacing is 10m, can accelerate the convergence of the iterative inversion and improve results. The accuracy of the estimated positions from the travel time date is enough for the VCS data processing.

Asakawa, E.; Murakami, F.; Tsukahara, H.; Mizohata, S.; Ishikawa, K.

2013-12-01

470

Vertical Cable Seismic Survey for SMS exploration  

NASA Astrophysics Data System (ADS)

The Vertical Cable Seismic (VCS) survey is one of the reflection seismic methods. It uses hydrophone arrays vertically moored from the seafloor to record acoustic waves generated by sea-surface, deep-towed or ocean bottom sources. Analyzing the reflections from the sub-seabed, we could look into the subsurface structure. Because the VCS is an efficient high-resolution 3D seismic survey method for a spatially-bounded area, we proposed it for the SMS survey tool development program that the Ministry of Education, Culture, Sports, Science and Technology (MEXT) started in 2009. We have been developing the VCS survey system, including not only data acquisition hardware but data processing and analysis technique. We carried out several VCS surveys combining with surface towed source, deep towed source and ocean bottom source. The water depths of these surveys are from 100m up to 2100 m. Through these experiments, our VCS data acquisition system has been also completed. But the data processing techniques are still on the way. One of the most critical issues is the positioning in the water. The uncertainty in the positions of the source and of the hydrophones in water degraded the quality of subsurface image. GPS navigation system is available on sea surface, but in case of deep-towed source or ocean bottom source, the accuracy of shot position with SSBL/USBL is not sufficient for the very high-resolution imaging. We have developed a new approach to determine the positions in water using the travel time data from the source to VCS hydrophones. In 2013, we have carried out the second VCS survey using the surface-towed high-voltage sparker and ocean bottom source in the Izena Cauldron, which is one of the most promising SMS areas around Japan. The positions of ocean bottom source estimated by this method are consistent with the VCS field records. The VCS data with the sparker have been processed with 3D PSTM. It gives the very high resolution 3D volume deeper than two hundred meters. Our VCS system has been demonstrated as a promising survey tool for the SMS exploration.

Asakawa, Eiichi; Murakami, Fumitoshi; Tsukahara, Hotoshi; Mizohata, Shigeharu

2014-05-01

471

Vertically homogeneous stationary tornado-type vortex  

NASA Astrophysics Data System (ADS)

Tornado is regarded as one of the most dangerous atmosphere phenomena. The tornado phenomenon has been intensively studied so far, however, there is still no established and accepted theory of how tornadoes form, an uncertainty still exists concerning extreme winds and pressure drops in tornadoes. It is commonly accepted that it is possible to describe tornado from the set of nonlinear hydrodynamical equations, however, it is still unclear which non-linear processes are responsible for its formation. Nonlinear terms in the system are associated with either centrifugal force, or entropy transport, or transport of humidity. It appears that the amount and spatial distribution of precipitation with the convection are important indicators of the weather phenomena associated with a particular storm. The low-precipitation supercells that produce relatively little precipitation and yet show clear visual signs of rotation. Low-precipitation supercells occur most often near the surface dryline and, owing to the sparse precipitation and relatively dry environments with little cloudiness. Low-precipitation storms are frequently non-tornadic and many are non-severe despite exhibiting persistent rotation. On the other hand, the so-called high-precipitation storms are characterized by substantial precipitation within their mesocyclonic circulations. When high-precipitation storms have a recognizable hook radar echo, reflectivity in the hook is comparable to those in the precipitation core. High-precipitation supercells are probably the most common form of supercell and produce severe weather of all types including tornadoes. Therefore, in this work we consider a hydrodynamic system with only one nonlinear term associated with atmosphere humidity, which yields energy to the system. The tornado vortex is usually to a good approximation cylindrical so we use cylindrical geometry and homogeneity in vertical direction. In this case the problem reduces to a system of ordinary differential equations. Rotation in the vortex is associated with compressibility so we also take into account the compressibility of the gas. Under certain approximations the problem reduces to a single high-order nonlinear equation. Numerical solution of the obtained high-order equation describes all three velocity components and all thermodynamic parameters in the system. The system exhibits high rotation and strong vertical air flow in the middle part of the vortex.

Rutkevich, P. B.; Rutkevych, P. P.

2010-05-01

472

Vertically resolved aerosol properties by multi-wavelength lidar measurements  

NASA Astrophysics Data System (ADS)

An approach based on the graphical method of Gobbi and co-authors (2007) is introduced to estimate the dependence on altitude of the aerosol fine mode radius (Rf) and of the fine mode contribution (?) to the aerosol optical thickness (AOT) from three-wavelength lidar measurements. The graphical method of Gobbi and co-authors (2007) was applied to AERONET (AErosol RObotic NETwork) spectral extinction observations and relies on the combined analysis of the Ångstrom exponent (å) and its spectral curvature ?å. Lidar measurements at 355, 532 and 1064 nm were used in this study to retrieve the vertical profiles of å and ?å and to estimate the dependence on altitude of Rf and ?(532 nm) from the å-?å combined analysis. Lidar measurements were performed at the Department of Mathematics and Physics of the Universita' del Salento, in south-eastern Italy. Aerosol from continental Europe, the Atlantic, northern Africa, and the Mediterranean Sea are often advected over south-eastern Italy and as a consequence, mixed advection patterns leading to aerosol properties varying with altitude are dominant. The proposed approach was applied to ten measurement days to demonstrate its feasibility in different aerosol load conditions. The selected days were characterized by AOTs spanning the 0.26-0.67, 0.15-0.39, and 0.04-0.27 range at 355, 532, and 1064 nm, respectively. Mean lidar ratios varied within the 31-83, 32-84, and 11-47 sr range at 355, 532, and 1064 nm, respectively, for the high variability of the aerosol optical and microphysical properties. å values calculated from lidar extinction profiles at 355 and 1064 nm ranged between 0.1 and 2.5 with a mean value ± 1 standard deviation equal to 1.3 ± 0.7. ?å varied within the -0.1-1 range with mean value equal to 0.25 ± 0.43. Rf and ?(532 nm) values spanning the 0.05-0.3 ?m and the 0.3-0.99 range, respectively, were associated with the å-?å data points. Rf and ? values showed no dependence on the altitude. 60% of the data points were in the ?å-å space delimited by the ? and Rf curves varying within 0.80-0.99 and 0.05-0.15 ?m, respectively, for the dominance of fine-mode particles in driving the AOT over south-eastern Italy. Vertical profiles of the linear particle depolarization ratio retrieved from lidar measurements, aerosol products from AERONET sun photometer measurements collocated in space and time, analytical back trajectories, satellite true colour images, and dust concentrations from the BSC-DREAM (Barcelona Super Computing Center-Dust REgional Atmospheric Model) model were used to demonstrate the robustness of the proposed method.

Perrone, M. R.; De Tomasi, F.; Gobbi, G. P.

2014-02-01

473

Properties of vertically self-gravitating accretion discs with a dissipative corona  

E-print Network

The steady-state structure of a disc with a corona is analyzed when the vertical component of the gravitational force due to the self-gravity of the disc is considered. For the energy exchange between the disc and the corona, we assume a fraction f of the dissipated energy inside the accretion disc is transported to the corona via the magnetic tubes. Analytical solutions corresponding to a prescription for f (in which this parameter directly depends on the ratio of the gas pressure to the total pressure) or free f are presented and their physical properties are studied in detail. We show that the existence of the corona not only decreases the temperature of the disc, but also increases the surface density.The vertical component of the gravitational force due to the self-gravity of the disc decreases the self-gravitating radius and the mass of the fragments at this radius. However, as more energy is transported from the disc to the corona, the effect of the vertical component of the gravitational force due to the self-gravity of the disc on the self-gravitating radius becomes weaker, though the mass of the fragments is reduced irrespective of the amount of the energy exchange from the disc to the corona.

Fazeleh Khajenabi; Peter Duffy

2008-05-30

474

Efficiency improvement of a vertical light-emitting diode through surface plasmon coupling and grating scattering.  

PubMed

The enhancement of output intensity, the generation of polarized output, and the reduction of the efficiency droop effect in a surface plasmon (SP) coupled vertical light-emitting diode (LED) with an Ag nano-grating structure located between the p-GaN layer and the wafer bonding metal for inducing SP coupling with the InGaN/GaN quantum wells (QWs) are demonstrated. In fabricating the vertical LED, the patterned sapphire substrate is remov