ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Formation of regular step arrays on Si(111)7×7 (1998)

Lin, J.-L. ; Petrovykh, D. Y. ; Viernow, J. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 84 (1998), S. 255-260

add to mindlist on the mindlist

Details

ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: Highly regular arrays of steps are produced on vicinal Si(111)7×7 surfaces. A tilt of the surface normal from (111) toward (1¯1¯2) produces single steps (0.3 nm high and typically 15 nm apart). The opposite tilt toward (112¯) produces bunched steps with adjustable height (1–5 nm) and a spacing of 70 nm. Preparation criteria for straight edges and regular spacings are determined, taking into account the miscut angle (azimuthal and polar), annealing sequence, current direction, and applied stress. © 1998 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.368077

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Nonlinear estimation of spatial distribution of rainfall — An indicator cokriging approach (1996)

Seo, D-J

Springer

Stochastic environmental research and risk assessment 10 (1996), S. 127-150

add to mindlist on the mindlist

Details

ISSN: 1436-3259

Keywords: Rainfall estimation ; indicator cokriging ; rain gage measurements

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract Indicator cokriging (Journel 1983) is examined as a tool for real-time estimation of rainfall from rain gage measurements. The approach proposed in this work obviates real-time estimation of real-time statistics of rainfall by using ensemble or climatological statistics exclusively, and reduces computational requirements attendant to indicator cokriging by employing only a few auxiliary cutoffs in estimation of conditional probabilities. Due to unavailability of suitable rain gage measurements, hourly radar rain fall data were used for both indicator covariance estimation and a comparative evaluation. Preliminary results suggest that the indicator cokriging approach is clearly superior to its ordinary kriging counterpart, whereas the indicator kriging approach is not. The improvement is most significant in estimation of light rainfall, but drops off significantly for heavy rainfall. The lack of predictability in spatial estimation of heavy rainfall is borne out in the integral scale of indicator correlation: peaking to its maximum for cutoffs near the median, indicator correlation scale becomes increasingly smaller for larger cutoffs of rainfall depth. A derived-distribution analysis, based on the assumption that radar rainfall is a linear sum of ground-truth and a random error, suggests that, at low cutoffs, indicator correlation scale of ground-truth can significantly differ from that of radar rainfall, and points toward inclusion of rainfall intermittency, for example, within the framework proposed in this work.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01581763

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

Rainfall estimation using raingages and radar — A Bayesian approach: 2. An application (1991)

Seo, D. -J. ; Smith, J. A.

Springer

Stochastic environmental research and risk assessment 5 (1991), S. 31-44

add to mindlist on the mindlist

Details

ISSN: 1436-3259

Keywords: Radar rainfall ; gage rainfall ; parameter uncertainty ; Bayesian estimation

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract In Seo and Smith (this issue), a set of estimators was built in a Bayesian framework to estimate rainfall depth at an ungaged location using raingage measurements and radar rainfall data. The estimators are equivalent to lognormal co-kriging (simple co-kriging in the Gaussian domain) with uncertain mean and variance of gage rainfall. In this paper, the estimators are evaluated via cross-validation using hourly radar rainfall data and simulated hourly raingage data. Generation of raingage data is based on sample statistics of actual raingage measurements and radar rainfall data. The estimators are compared with lognormal co-kriging and nonparametric estimators. The Bayesian estimators are shown to provide some improvement over lognormal co-kriging under the criteria of mean error, root mean square error, and standardized mean square error. It is shown that, if the prior could be assessed more accurately, the margin of improvement in predicting estimation variance could be larger. In updating the uncertain mean and variance of gage rainfall, inclusion of radar rainfall data is seen to provide little improvement over using raingage data only.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01544176

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

Rainfall estimation using raingages and radar — A Bayesian approach: 1. Derivation of estimators (1991)

Seo, D. -J. ; Smith, J. A.

Springer

Stochastic environmental research and risk assessment 5 (1991), S. 17-29

add to mindlist on the mindlist

Details

ISSN: 1436-3259

Keywords: Co-kriging ; parameter uncertainty ; Bayesian estimation ; radar rainfall ; gage rainfall

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract Procedures for estimating rainfall from radar and raingage observations are constructed in a Bayesian framework. Given that the number of raingage measurements is typically very small, mean and variance of gage rainfall are treated as uncertain parameters. Under the assumption that log gage rainfall and log radar rainfall are jointly multivariate normal, the estimation problem is equivalent to lognormal co-kriging with uncertain mean and variance of the gage rainfall field. The posterior distribution is obtained under the assumption that the prior for the mean and inverse of the variance of log gage rainfall is normal-gamma 2. Estimate and estimation variance do not have closed-form expressions, but can be easily evaluated by numerically integrating two single integrals. To reduce computational burden associated with evaluating sufficient statistics for the likelihood function, an approximate form of parameter updating is given. Also, as a further approximation, the parameters are updated using raingage measurements only, yielding closed-form expressions for estimate and estimation variance in the Gaussian domain. With a reduction in the number of radar rainfall data in constructing covariance matrices, computational requirements for the estimation procedures are not significantly greater than those for simple co-kriging. Given their generality, the estimation procedures constructed in this work are considered to be applicable in various estimation problems involving an undersampled main variable and a densely sampled auxiliary variable.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01544175

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

Spatial rainfall estimation by linear and non-linear co-kriging of radar-rainfall and raingage data (1989)

Azimi-Zonooz, A. ; Krajewski, W. F. ; Bowles, D. S. ; [et al.]

Springer

Stochastic environmental research and risk assessment 3 (1989), S. 51-67

add to mindlist on the mindlist

Details

ISSN: 1436-3259

Keywords: Spatial rainfall estimation ; kriging ; ordinary co-kriging ; disjunctive co-kriging

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract The feasibility of linear and nonlinear geostatistical estimation techniques for optimal merging of rainfall data from raingage and radar observations is investigated in this study by use of controlled numerical experiments. Synthetic radar and raingage data are generated with their hypothetical error structures that explicitly account for sampling characteristics of the two sensors. Numerically simulated rainfall fields considered to be ground-truth fields on 4×4 km grids are used in the generation of radar and raingage observations. Ground-truth rainfall fields consist of generated rainfall fields with various climatic characteristics that preserve the space-time covariance function of rainfall events in extratropical cyclonic storms. Optimal mean areal precipitation estimates are obtained based on the minimum variance, unbiased property of kriging techniques under the second order homogeneity assumption of rainfall fields. The evaluation of estimated rainfall fields is done based on the refinement of spatial predictability over what would be provided from each sensor individually. Attention is mainly given to removal of measurement error and bias that are synthetically introduced to radar measurements. The influence of raingage network density on estimated rainfall fields is also examined.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01543427

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Electronic Resource

The effect of metal carbonate fluxes on the crystallinity, morphology, and photoluminescence characteristics of Y2O3:Eu phosphor in spray pyrolysis (2000)

Kang, Y. C. ; Roh, H. S. ; Seo, D. J. ; [et al.]

Springer

Journal of materials science 19 (2000), S. 1225-1227

add to mindlist on the mindlist

Details

ISSN: 1573-4811

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1006705025294

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

7

Unknown

Assessment and Implications of NCEP Stage IV Quantitative Precipitation Estimates for Product Intercomparisons (2016)

Nelson, Brian R. ; Prat, Olivier P. ; Seo, D.-J. ; [et al.]

American Meteorological Society

In: Weather and Forecasting. 2016; 31(2): 371-394. Published 2016 Feb 26. doi: 10.1175/waf-d-14-00112.1.

add to mindlist on the mindlist

Details

Publication Date: 2016-02-26

Description: The National Centers for Environmental Prediction (NCEP) stage IV quantitative precipitation estimates (QPEs) are used in many studies for intercomparisons including those for satellite QPEs. An overview of the National Weather Service precipitation processing system is provided here so as to set the stage IV product in context and to provide users with some knowledge as to how it is developed. Then, an assessment of the stage IV product over the period 2002–12 is provided. The assessment shows that the stage IV product can be useful for conditional comparisons of moderate-to-heavy rainfall for select seasons and locations. When evaluating the product at the daily scale, there are many discontinuities due to the operational processing at the radar site as well as discontinuities due to the merging of data from different River Forecast Centers (RFCs) that use much different processing algorithms for generating their precipitation estimates. An assessment of the daily precipitation estimates is provided based on the cumulative distribution function for all of the daily estimates for each RFC by season. In addition it is found that the hourly estimates at certain RFCs suffer from lack of manual quality control and caution should be used.

Print ISSN: 0882-8156

Electronic ISSN: 1520-0434

Topics: Geography , Physics