scholarly journals Benchmark data for verifying background model implementations in orbit and gravity field determination software

2020 ◽  
Vol 55 ◽  
pp. 1-11
Author(s):  
Martin Lasser ◽  
Ulrich Meyer ◽  
Adrian Jäggi ◽  
Torsten Mayer-Gürr ◽  
Andreas Kvas ◽  
...  

Abstract. In the framework of the COmbination Service for Time-variable Gravity fields (COST-G) gravity field solutions from different analysis centres are combined to provide a consolidated solution of improved quality and robustness to the user. As in many other satellite-related sciences, the correct application of background models plays a crucial role in gravity field determination. Therefore, we publish a set of data of various commonly used forces in orbit and gravity field modelling (Earth's gravity field, tides etc.) evaluated along a one day orbit arc of GRACE, together with auxiliary data to enable easy comparisons. The benchmark data is compiled with the GROOPS software by the Institute of Geodesy (IfG) at Graz University of Technology. It is intended to be used as a reference data set and provides the opportunity to test the implementation of these models at various institutions involved in orbit and gravity field determination from satellite tracking data. In view of the COST-G GRACE and GRACE Follow-On gravity field combinations, we document the outcome of the comparison of the background force models for the Bernese GNSS software from AIUB (Astronomical Institute, University of Bern), the EPOS software of the German Research Centre for Geosciences (GFZ), the GINS software, developed and maintained by the Groupe de Recherche de Géodésie Spatiale (GRGS), the GRACE-SIGMA software of the Leibniz University of Hannover (LUH) and the GRASP software also developed at LUH. We consider differences in the force modelling for GRACE (-FO) which are one order of magnitude smaller than the accelerometer noise of about 10−10 m s−2 to be negligible and formulate this as a benchmark for new analysis centres, which are interested to contribute to the COST-G initiative.

2020 ◽  
Author(s):  
Martin Lasser ◽  
Torsten Mayer-Gürr ◽  
Andreas Kvas ◽  
Igor Koch ◽  
Jean-Michel Lemoine ◽  
...  

<div>In the framework of the COmbination Service of Time-variable Gravity fields (COST-G) gravity field solutions from different analysis centres are combined to provide a consolidated solution of improved quality to the user. As in many other satellite-related sciences, the correct application of background models plays a crucial role in gravity field determination. Therefore, we publish a set of data of various commonly used forces in orbit and gravity field modelling (gravity field, tides etc.) evaluated along a one day orbit arc of GRACE, together with some additional data to enable easy comparisons. The benchmark data is compiled with the GROOPS software by the Institute of Geodesy (IfG) at Graz University of Technology. It is intended to be used as a reference and provides the opportunity to test the implementation of these models at various analysis centres. In view of the COST-G GRACE (-FO) gravity field combinations, we show the outcome of such a background force field software validation for the GRACE-SIGMA software of the Leibniz University of Hannover (LUH), the GRGS GINS software, EPOS of the German Research Centre for Geosciences (GFZ) and the Bernese GNSS software from AIUB (Astronomical Institute, University of Bern). We consider differences in the force modelling for GRACE (-FO) of one order of magnitude less than the accelerometer noise to be negligible, and make an attempt to quantify and explain differences exceeding this threshold.</div>


2020 ◽  
Author(s):  
Qiujie Chen ◽  
Yunzhong Shen ◽  
Xingfu Zhang ◽  
Jürgen Kusche

<p>Due to the battery issue, the Gravity Recovery and Climate Experiment (GRACE) mission unfortunately came to an end in October 2017 after providing more than 15 years of mass transport information of our changing planet. To continue to monitoring the mass transport in the Earth system, the GRACE Follow-On (GRACE-FO) was launched in May 2018. As a new feature of GRACE-FO, a Laser Ranging Interferometer (LRI) was equipped to measure the inter-satellite range at a nanometer level. Since May 2019, GRACE-FO Level-1B observations have been made available to our community. Using the GRACE-FO Level-1B observations without laser ranging information, preliminary GRACE-FO gravity field solutions from Center for Space Research (CSR), GeoForschungsZentrum (GFZ), Jet Propulsion Laboratory (JPL) and Graz University of Technology have been released. Incorporating laser ranging observations into gravity field determination, a preliminary time series of GRACE-FO gravity field solutions has been derived from Tongji University in collaboration with University of Bonn. In this paper, the signal and noise of our gravity field solutions are analyzed and compared to those from other research groups. Our results show that the laser ranging observations with a sampling rate of 2s are able to improve gravity field solutions by about 7% in terms of geoid degree variances up to degree and order 96 as compared to the K-Band ranging data with a sampling rate of 5s.</p>


1998 ◽  
Vol 30 (10) ◽  
pp. 1857-1872 ◽  
Author(s):  
S Openshaw

The author investigates the extent to which smart computational methods can be used to create new and better performing types of spatial interaction model. He briefly describes the application of three different computationally intensive modelling technologies and compares the performance of the resulting models on a benchmark data set. It would appear that performance improvements of up to a factor of two can be obtained at the cost of a few orders of magnitude increase in compute times.


2021 ◽  
Author(s):  
Martin Lasser ◽  
Ulrich Meyer ◽  
Daniel Arnold ◽  
Adrian Jäggi

<p>A key component of any model is the accurate specification of its quality. In gravity field modelling from satellite data, as it is done with the observation collected by GRACE Follow-On, usually least-squares adjustments are performed to obtain a monthly solution of the Earth’s gravity field. However,<br>the jointly estimated formal errors usually do not reflect the error level that could be expected but provides much lower error estimates. We take the Celestial Mechanics Approach (CMA), developed at the Astronomical Institute, University of Bern (AIUB), and extend it by an empirical modelling of the noise based on the post-fit residuals between the final GRACE Follow-On orbits, that are co-estimated together with the gravity field, and the   observations, expressed in position residuals to the kinematic positions and in K-band range-rate residuals. We compare and validate the solutions that employ empirical modelling with solutions that do not contain sophisticated noise modelling by examining the stochastic behaviour of the respective post-fit residuals, by investigating areas where a low noise is expected and by inspecting the mass trend estimates in certain areas of global interest. Finally, we investigate the influence of the empirically weighted solutions in a combination of monthly gravity fields based on other approaches as it is done in the COST-G framework.</p>


2011 ◽  
Vol 14 (2) ◽  
Author(s):  
Thomas G Koch

Current estimates of obesity costs ignore the impact of future weight loss and gain, and may either over or underestimate economic consequences of weight loss. In light of this, I construct static and dynamic measures of medical costs associated with body mass index (BMI), to be balanced against the cost of one-time interventions. This study finds that ignoring the implications of weight loss and gain over time overstates the medical-cost savings of such interventions by an order of magnitude. When the relationship between spending and age is allowed to vary, weight-loss attempts appear to be cost-effective starting and ending with middle age. Some interventions recently proven to decrease weight may also be cost-effective.


2014 ◽  
Vol 112 (11) ◽  
pp. 2729-2744 ◽  
Author(s):  
Carlo J. De Luca ◽  
Joshua C. Kline

Over the past four decades, various methods have been implemented to measure synchronization of motor-unit firings. In this work, we provide evidence that prior reports of the existence of universal common inputs to all motoneurons and the presence of long-term synchronization are misleading, because they did not use sufficiently rigorous statistical tests to detect synchronization. We developed a statistically based method (SigMax) for computing synchronization and tested it with data from 17,736 motor-unit pairs containing 1,035,225 firing instances from the first dorsal interosseous and vastus lateralis muscles—a data set one order of magnitude greater than that reported in previous studies. Only firing data, obtained from surface electromyographic signal decomposition with >95% accuracy, were used in the study. The data were not subjectively selected in any manner. Because of the size of our data set and the statistical rigor inherent to SigMax, we have confidence that the synchronization values that we calculated provide an improved estimate of physiologically driven synchronization. Compared with three other commonly used techniques, ours revealed three types of discrepancies that result from failing to use sufficient statistical tests necessary to detect synchronization. 1) On average, the z-score method falsely detected synchronization at 16 separate latencies in each motor-unit pair. 2) The cumulative sum method missed one out of every four synchronization identifications found by SigMax. 3) The common input assumption method identified synchronization from 100% of motor-unit pairs studied. SigMax revealed that only 50% of motor-unit pairs actually manifested synchronization.


2006 ◽  
Vol 27 (3) ◽  
pp. 365-375 ◽  
Author(s):  
Delfi Sanuy ◽  
Christoph Leskovar ◽  
Neus Oromi ◽  
Ulrich Sinsch

AbstractDemographic life history traits were investigated in three Bufo calamita populations in Germany (Rhineland-Palatinate: Urmitz, 50°N; 1998-2000) and Spain (Catalonia: Balaguer, Mas de Melons, 41°N; 2004). We used skeletochronology to estimate the age as number of lines of arrested growth in breeding adults collected during the spring breeding period (all localities) and during the summer breeding period (only Urmitz). A data set including the variables sex, age and size of 185 males and of 87 females was analyzed with respect to seven life history traits (age and size at maturity of the youngest first breeders, age variation in first breeders, longevity, potential reproductive lifespan, median lifespan, age-size relationship). Spring and summer cohorts at the German locality differed with respect to longevity and potential reproductive lifespan by one year in favour of the early breeders. The potential consequences on fitness and stability of cohorts are discussed. Latitudinal variation of life history traits was mainly limited to female natterjacks in which along a south-north gradient longevity and potential reproductive lifespan increased while size decreased. These results and a review of published information on natterjack demography suggest that lifetime number of offspring seem to be optimized by locally different trade-offs: large female size at the cost of longevity in southern populations and increased longevity at the cost of size in northern ones.


2018 ◽  
Vol 21 (2) ◽  
pp. 62-71
Author(s):  
Henry O’Lawrence ◽  
Rohan Chowlkar

Purpose The purpose of this paper is to determine the cost effectiveness of palliative care on patients in a home health and hospice setting. Secondary data set was utilized to test the hypotheses of this study. Home health care and hospice care services have the potential to avert hospital admissions in patients requiring palliative care, which significantly affects medicare spending. With the aging population, it has become evident that demand of palliative care will increase four-fold. It was determined that current spending on end-of-life care is radically emptying medicare funds and fiscally weakening numerous families who have patients under palliative care during life-threatening illnesses. The study found that a majority of people registering for palliative and hospice care settings are above the age group of 55 years old. Design/methodology/approach Different variables like length of stay, mode of payment and disease diagnosis were used to filter the available data set. Secondary data were utilized to test the hypothesis of this study. There are very few studies on hospice and palliative care services and no study focuses on the cost associated with this care. Since a very large number of the USA, population is turning 65 and over, it is very important to analyze the cost of care for palliative and hospice care. For the purpose of this analysis, data were utilized from the National Home and Hospice Care Survey (NHHCS), which has been conducted periodically by the Centers for Disease Control and Prevention’s National Center for Health Statistics. Descriptive statistics, χ2 tests and t-tests were used to test for statistical significance at the p<0.05 level. Findings The Statistical Package for Social Sciences (SPSS) was utilized for this result. H1 predicted that patients in the age group of 65 years and up have the highest utilization of home and hospice care. This study examined various demographic variables in hospice and home health care which may help to evaluate the cost of care and the modes of payments. This section of the result presents the descriptive analysis of dependent, independent and covariate variables that provide the overall national estimates on differences in use of home and hospice care in various age groups and sex. Research limitations/implications The data set used was from the 2007 NHHCS survey, no data have been collected thereafter, and therefore, gap in data analysis may give inaccurate findings. To compensate for this gap in the data set, recent studies were reviewed which analyzed cost in palliative care in the USA. There has been a lack of evidence to prove the cost savings and improved quality of life in palliative/hospice care. There is a need for new research on the various cost factors affecting palliative care services as well as considering the quality of life. Although, it is evident that palliative care treatment is less expensive as compared to the regular care, since it eliminates the direct hospitalization cost, but there is inadequate research to prove that it improves the quality of life. A detailed research is required considering the additional cost incurred in palliative/hospice care services and a cost-benefit analysis of the same. Practical implications While various studies reporting information applicable to the expenses and effect of family caregiving toward the end-of-life were distinguished, none of the previous research discussed this issue as their central focus. Most studies addressed more extensive financial effect of palliative and end-of-life care, including expenses borne by the patients themselves, the medicinal services framework and safety net providers or beneficent/willful suppliers. This shows a significant hole in the current writing. Social implications With the aging population, it has become evident that demand of palliative/hospice care will increase four-fold. The NHHCS have stopped keeping track of the palliative care requirements after 2007, which has a negative impact on the growing needs. Cost analysis can only be performed by analyzing existing data. This review has recognized a huge niche in the evidence base with respect to the cost cares of giving care and supporting a relative inside a palliative/hospice care setting. Originality/value The study exhibited that cost diminishments in aggressive medications can take care of the expenses of palliative/hospice care services. The issue of evaluating result in such a physically measurable way is complicated by the impalpable nature of large portions of the individual components of outcome. Although physical and mental well-being can be evaluated to a certain degree, it is significantly more difficult to gauge in a quantifiable way, the social and profound measurements of care that help fundamentally to general quality of care.


2002 ◽  
Vol 137 (2) ◽  
pp. 111-126 ◽  
Author(s):  
Yoshinori Nakahara ◽  
Kenya Suyama ◽  
Jun Inagawa ◽  
Ryuji Nagaishi ◽  
Setsumi Kurosawa ◽  
...  

Author(s):  
Agustina Malvido Perez Carletti ◽  
Markus Hanisch ◽  
Jens Rommel ◽  
Murray Fulton

AbstractIn this paper, we use a unique data set of the prices paid to farmers in Argentina for grapes to examine the prices paid by non-varietal wine processing cooperatives and investor-oriented firms (IOFs). Motivated by contrasting theoretical predictions of cooperative price effects generated by the yardstick of competition and property rights theories, we apply a multilevel regression model to identify price differences at the transaction level and the departmental level. On average, farmers selling to cooperatives receive a 3.4 % lower price than farmers selling to IOFs. However, we find cooperatives pay approximately 2.4 % more in departments where cooperatives have larger market shares. We suggest that the inability of cooperatives to pay a price equal to or greater than the one paid by IOFs can be explained by the market structure for non-varietal wine in Argentina. Specifically, there is evidence that cooperative members differ from other farmers in terms of size, assets and the cost of accessing the market. We conclude that the analysis of cooperative pricing cannot solely focus on the price differential between cooperatives and IOFs, but instead must consider other factors that are important to the members.


Sign in / Sign up

Export Citation Format

Share Document