Implementation of GRACE and GRACE-FO observation covariance estimates at JPL

2020 ◽  
Author(s):  
Matthias Ellmer ◽  
David Wiese ◽  
Christopher McCullough ◽  
Dah-Ning Yuan ◽  
Eugene Fahnestock
Keyword(s):  
Gravity Field ◽  
Time Domain ◽  
Stochastic Models ◽  
Carrier Phase ◽  
State Of The Art ◽  
Water Storage ◽  
Laser Ranging ◽  
Least Squares Estimate ◽  
Current State ◽  
The Time Domain

<p class="Standard">Developing meaningful uncertainty quantifications for GRACE or GRACE-FO derived products, e.g. water storage anomalies, requires a robust understanding of the information and noise content in the observables employed in their estimation.</p> <p class="Textbody">The stochastic models for GRACE and GRACE-FO K-Band, and GPS carrier phase and pseudorange observables employed in upcoming JPL solutions will be presented. Within these models, the time-domain correlations for each of the observations are estimated, and then applied in the least squares estimate of monthly gravity field solutions. Reproducing results from other groups, the resulting formal errors of monthly solutions are improved.</p> <p class="Standard">We compare this approach to the current state of the art at JPL, and show that noise content in the determined gravity field solutions is reduced. We further demonstrate the application of this method to data from the GRACE-FO Laser ranging interferometer.</p>

Implementation of GRACE and GRACE-FO observation covariance estimates at JPL

2020 ◽  
Author(s):  
Matthias Ellmer ◽  
David Wiese ◽  
Christopher McCullough ◽  
Dah-Ning Yuan ◽  
Eugene Fahnestock
Keyword(s):  
Least Squares ◽  
Gravity Field ◽  
Time Domain ◽  
Stochastic Models ◽  
Carrier Phase ◽  
Water Storage ◽  
User Community ◽  
Least Squares Estimate ◽  
Level 3 ◽  
The Time Domain

<p>Developing meaningful uncertainty quantifications for GRACE or GRACE-FO derived products, e.g. water storage anomalies, requires a robust understanding of the information and noise content in the observables employed in their estimation.</p><p>The stochastic models for GRACE and GRACE-FO K-Band, LRI, and GPS carrier phase and pseudorange observables employed in upcoming JPL solutions, along with notes on their implementation and development, will be presented. Within these models, the time-domain correlations for each of the observations are estimated, and then applied in the least squares estimate of monthly gravity field solutions. Reproducing results from other groups, the resulting formal errors of monthly solutions are improved.</p><p>It is envisioned that possible new Level 3 products can make these improved uncertainty quantifications accessible to the GRACE user community at large. Possible specifications for such products will be presented, and feedback from the community and discussion will be appreciated.</p>

scholarly journals CARACTERIZAÇÃO DA DISTRIBUIÇÃO DA ÁGUA NO SOLO PARA IRRIGAÇÃO POR GOTEJAMENTO

Irriga ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 564-577 ◽  
Author(s):  
Leonardo Do Nascimento Lopes ◽  
Elton Martins ◽  
Bruno De Lima Santoro ◽  
Claudinei Fonseca Souza
Keyword(s):  
Water Content ◽  
Time Domain ◽  
Water Distribution ◽  
Water Storage ◽  
Time Domain Reflectometry ◽  
Wetting Front ◽  
Applied Water ◽  
Flow Rates ◽  
Abstract Knowledge ◽  
The Time Domain

CARACTERIZAÇÃO DA DISTRIBUIÇÃO DA ÁGUA NO SOLO PARA IRRIGAÇÃO POR GOTEJAMENTO  Leonardo do Nascimento Lopes1; Elton Martins2; Bruno de Lima Santoro2; Claudinei Fonseca Souza31Universidade de Taubaté, Unitau, Taubaté, SP,  [email protected] Engenharia Civil e Ambiental, Universidade de Taubaté, Taubaté, Unitau, SP 3Departamento de Recursos Naturais e Proteção Ambiental, Universidade Federal São Carlos, São Carlos, SP  1 RESUMO O conhecimento da distribuição da água no solo é de grande importância para a agricultura, uma vez que a água é um dos fatores que mais influenciam o rendimento das culturas. Existem muitas técnicas utilizadas para o monitoramento do conteúdo de água do solo, a reflectometria domínio do tempo (TDR) tem sido difundida entre os pesquisadores por apresentar várias vantagens, entre as quais a determinação em tempo real e a possibilidade de leituras automatizadas. O principal objetivo desta pesquisa foi avaliar a distribuição da água no perfil de um Latossolo Vermelho-Amarelo. Sondas de Reflectometria no domínio do Tempo (TDR) foram utilizadas para monitorar a distribuição de água no solo aplicada através de gotejadores de fluxo constante nas taxas de 2, 4 e 8 Lh-1. Considerando os resultados de diferentes perfis, observa-se um maior armazenamento da água próximo do gotejador diminuindo progressivamente para frente de molhamento. Aproximadamente, um terço da água aplicada (33%) foi armazenado na primeira camada (0-0,10 m) para todos os ensaios. Comparando diferentes taxas de aplicação, observa-se maior armazenamento de água para o gotejador de 8L h-1, com 30, 33 e 34% de água aplicada acumulada na primeira camada (0-0.10 m) para gotejadores de 2, 4 e 8L h-1, respectivamente. Os resultados sugerem que, com base no volume e frequência utilizada neste experimento, seria vantajoso aplicar pequenas quantidades de água em intervalos mais frequentes para reduzir perdas por percolação. UNITERMOS: TDR, conteúdo de água, bulbo molhado  LOPES, L. N.; MARTINS, E.; SANTORO, B. L.; SOUZA, C. F.WATER DISTRIBUTION CHARACTERIZATION IN SOIL FOR DRIP IRRIGATION   2 ABSTRACT Knowledge of water distribution in soil is of great importance to agriculture, since water is one of the factors that most influence the yield of crops. There are many techniques used to monitor soil water content. The time domain reflectometry (TDR) has been widespread among researchers because it presents several advantages, among which the determination in real time and possibility of automated readings. The main goal of this research was to evaluatethe water distribution in a profile of Red-Yellow Oxisol. Time domain reflectometry (TDR) probes were used to monitor the water distribution from drippers discharging at constant flow rates of 2, 4 and 8 Lh-1 in soil. Considering results from different profiles, we observed greater water storage near the dripper decreasing gradually towards the wetting front. About one third of the applied water (33%) was stored in the first layer (0-0.10 m) for all experiments. Comparing different dripper flow rates, we observed higher water storage for 8 L h-1, with 30, 33 and 34% of applied water accumulating in the first layer (0-0.10m) for dripper flow rates of 2, 4 and 8 L h-1, respectively. The results suggest that based on the volume and frequency used in this experiment, it would be advantageous to apply small amounts of water at more frequent intervals to reduce deep percolation losses of applied water. KEYWORDS: TDR, water content, wetted soil volume

scholarly journals Clutter Suppression for Staggered PRT Waveforms

2008 ◽  
Vol 25 (12) ◽  
pp. 2209-2218 ◽  
Author(s):  
Dmitri N. Moisseev ◽  
Cuong M. Nguyen ◽  
V. Chandrasekar
Keyword(s):  
Time Domain ◽  
State Of The Art ◽  
Radar Signal ◽  
Clutter Suppression ◽  
State University ◽  
Spectral Moments ◽  
Colorado State University ◽  
Current State ◽  
Repetition Time ◽  
State Water

Abstract This paper presents a clutter suppression methodology for staggered pulse repetition time (PRT) observations. It is shown that spectral moments of precipitation echoes can be accurately estimated even in cases where clutter-to-signal ratios are high by using a parametric time domain method (PTDM). Based on radar signal simulations, the accuracy of the proposed method is evaluated for various observation conditions. The performance of PTDM is demonstrated by the implementation of the staggered PRT at the Colorado State University–University of Chicago–Illinois State Water Survey (CSU–CHILL). Based on this study, it is found that the accuracy of the retrieval is comparable to the current state of the art methods applied to the uniformly sampled observations and that the estimated velocity is unbiased for the complete Nyquist range.

scholarly journals Accurate and efficient time-domain classification with adaptive spiking recurrent neural networks

2021 ◽  
Author(s):  
Bojian Yin ◽  
Federico Corradi ◽  
Sander M. Bohté
Keyword(s):  
Neural Networks ◽  
Time Domain ◽  
Recurrent Neural Networks ◽  
State Of The Art ◽  
Spiking Neurons ◽  
Recurrent Networks ◽  
Computationally Efficient ◽  
Hardware Implementations ◽  
Comparable Performance ◽  
The Time Domain

ABSTRACTInspired by more detailed modeling of biological neurons, Spiking neural networks (SNNs) have been investigated both as more biologically plausible and potentially more powerful models of neural computation, and also with the aim of extracting biological neurons’ energy efficiency; the performance of such networks however has remained lacking compared to classical artificial neural networks (ANNs). Here, we demonstrate how a novel surrogate gradient combined with recurrent networks of tunable and adaptive spiking neurons yields state-of-the-art for SNNs on challenging benchmarks in the time-domain, like speech and gesture recognition. This also exceeds the performance of standard classical recurrent neural networks (RNNs) and approaches that of the best modern ANNs. As these SNNs exhibit sparse spiking, we show that they theoretically are one to three orders of magnitude more computationally efficient compared to RNNs with comparable performance. Together, this positions SNNs as an attractive solution for AI hardware implementations.

scholarly journals Time-Domain Joint Training Strategies of Speech Enhancement and Intent Classification Neural Models

Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 374
Author(s):  
Mohamed Nabih Ali ◽  
Daniele Falavigna ◽  
Alessio Brutti
Keyword(s):  
Speech Enhancement ◽  
Time Domain ◽  
Background Noise ◽  
State Of The Art ◽  
Noisy Environments ◽  
Neural Models ◽  
Convolutional Network ◽  
Environmental Perturbations ◽  
Front End ◽  
The Time Domain

Robustness against background noise and reverberation is essential for many real-world speech-based applications. One way to achieve this robustness is to employ a speech enhancement front-end that, independently of the back-end, removes the environmental perturbations from the target speech signal. However, although the enhancement front-end typically increases the speech quality from an intelligibility perspective, it tends to introduce distortions which deteriorate the performance of subsequent processing modules. In this paper, we investigate strategies for jointly training neural models for both speech enhancement and the back-end, which optimize a combined loss function. In this way, the enhancement front-end is guided by the back-end to provide more effective enhancement. Differently from typical state-of-the-art approaches employing on spectral features or neural embeddings, we operate in the time domain, processing raw waveforms in both components. As application scenario we consider intent classification in noisy environments. In particular, the front-end speech enhancement module is based on Wave-U-Net while the intent classifier is implemented as a temporal convolutional network. Exhaustive experiments are reported on versions of the Fluent Speech Commands corpus contaminated with noises from the Microsoft Scalable Noisy Speech Dataset, shedding light and providing insight about the most promising training approaches.

Attenuation Estimation in Reflection: Progress and Prospects

1984 ◽  
Vol 6 (4) ◽  
pp. 349-395 ◽  
Author(s):  
J. Ophir ◽  
T. H. Shawker ◽  
N. F. Maklad ◽  
J. G. Miller ◽  
S. W. Flax ◽  
...  
Keyword(s):  
Time Domain ◽  
State Of The Art ◽  
Ultrasonic Attenuation ◽  
Clinical Results ◽  
Current State ◽  
Clinical Indications ◽  
Attenuation Estimation

This monograph presents a tutorial review of the current state-of-the-art in ultrasonic attenuation estimation in reflection. Clinical indications which provide the motivation for attempting in vivo attenuation estimation are discussed. Frequency and time domain techniques and their respective tradeoffs and problems are presented. Finally, current clinical results obtained with the various techniques are summarized and further areas of study are suggested.

Benchmarking of Analysis Tools for Thruster Assisted Mooring

2018 ◽  
Author(s):  
Daniel Merino Hoyos ◽  
Erik Falkenberg ◽  
Petter Stuberg
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
State Of The Art ◽  
Harsh Environments ◽  
Mooring Line ◽  
Shallow Waters ◽  
Sixth Generation ◽  
Analysis Technique ◽  
The Time Domain ◽  
Design Analyses

While the size of new built semi-submersibles is steadily increasing, their mooring systems are not experiencing a similar change. Most of the sixth-generation drilling units rely heavily on thruster assisted mooring to increase their operability in harsh environments and shallow waters. Frequency domain programs are commonly used to calculate mooring line tensions in the design analyses. This analysis technique assumes linearity in both the mooring system and the thruster assist controller. The study presented in this paper examines the validity of these assumptions by comparing frequency and time domain analyses in two state-of-the-art analysis programs. The linear thruster assist controller in frequency domain analyses is benchmarked against the Kalman filter-based controller in time domain simulations and against a real thruster assist controller coupled with the time domain software.

Modelling and Analysis of a Semi-Submersible Wind Turbine With a Central Tower With Emphasis on the Brace System

2013 ◽  
Author(s):  
Chenyu Luan ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Wind Turbine ◽  
Time Domain ◽  
Elastic System ◽  
State Of The Art ◽  
Limit State ◽  
Modeling Method ◽  
Ultimate Limit State ◽  
The Novel ◽  
Floating Wind Turbine ◽  
The Time Domain

This paper deals with analysis of the OC4 DeepCWind semi-submersible wind turbine, which is provided by NREL through the OC4 project. This concept is a three-column semi-submersible supporting a 5 MW wind turbine on an additional central column. The fact that the semi-submersible floater needs a large water line restoring moment to achieve sufficient stability and the control of the cost based on the steel weight make the design of braces and pontoons very challenging. Effective methods are needed to check the strength of the brace system based on the response forces and moments in the braces under different design environmental conditions, while the floating wind turbine is needed to be considered as an aero-hydro-servo-elastic system. A novel modeling methodology based on the code Simo/Riflex is introduced in this paper. Simo/Riflex is a state-of-the-art code that can account for the coupling effect between rigid body motions and slender structures (e.g. mooring lines, braces and blades) in the time-domain. Simo/Riflex can be combined with Aerodyn, which is a state-of-the-art aerodynamic code, to model the floating wind turbine as an aero-hydro-servo-elastic system, as well as be combined with simplified aerodynamic codes (e.g.TDHMILL) to improve the efficiency of the numerical simulation. The novel modeling method can give the forces and moments in the brace system of the floater under hydrodynamic and aerodynamic loads in the time-domain. In order to get the structural response of the braces, the side columns and the central supporting column are modeled as independent rigid bodies in Simo while the braces are modeled by beam elements in Riflex. Master and slave relationship is applied at the joints in between of the columns and braces. As an application example, the novel modeling method based on the code Simo/Riflex+TDHMILL, which is capable of modeling the floating wind turbine as an aero-hydro-elastic system, has been used to carry out Ultimate Limit State (ULS) design check for the brace system of the OC4 DeepCWind semi-submersible wind turbine based on relevant standards, i.e. NORSOK N00-3, NORSOK N-004, IEC61400-1, IEC61400-3. The modeling method can also be used by other codes which have similar features as Simo/Riflex.

Behavioral Genetics: Concepts for Research and Practice in Language Development and Disorders

1995 ◽  
Vol 38 (5) ◽  
pp. 1126-1142 ◽  
Author(s):  
Jeffrey W. Gilger
Keyword(s):  
Language Development ◽  
Behavioral Genetics ◽  
State Of The Art ◽  
Genetic Research ◽  
Great Promise ◽  
Behavioral Genetic ◽  
Fine Grained ◽  
Future Goals ◽  
Current State ◽  
Research Designs

This paper is an introduction to behavioral genetics for researchers and practioners in language development and disorders. The specific aims are to illustrate some essential concepts and to show how behavioral genetic research can be applied to the language sciences. Past genetic research on language-related traits has tended to focus on simple etiology (i.e., the heritability or familiality of language skills). The current state of the art, however, suggests that great promise lies in addressing more complex questions through behavioral genetic paradigms. In terms of future goals it is suggested that: (a) more behavioral genetic work of all types should be done—including replications and expansions of preliminary studies already in print; (b) work should focus on fine-grained, theory-based phenotypes with research designs that can address complex questions in language development; and (c) work in this area should utilize a variety of samples and methods (e.g., twin and family samples, heritability and segregation analyses, linkage and association tests, etc.).

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