scholarly journals On the performance of equiangular mascon solution in GRACE-like missions

2021 ◽  
Vol 64 (2) ◽  
Author(s):  
Abbas Abedini ◽  
Wolfgang Keller ◽  
Ali Reza Amiri-Simkooei
Keyword(s):  
Patch Size ◽  
Unknown Parameters ◽  
Objective Criterion ◽  
Equal Area ◽  
Area Of Interest ◽  
Novel Approach ◽  
Proper Size ◽  
Resolution Analysis ◽  
Computation Scheme ◽  
Gravity Recovery

Mass concentration (mascon) solutions for GRACE (Gravity Recovery and Climate Experiment) data are widely used in various regional-to-global mass change studies. The current advances in the mascon solution have mainly concentrated on improving the spatial resolution of the solution, enhancing the applied least-squares regularization, and the characterization of the solution errors. Most of the mascon solutions are obtained on the equal-area grid, inducing complexities in creating the grid and its presentation. In this regard, estimation of the mascon solutions on equiangular grids can be appealing. Furthermore, in the equal-area methods, there is no global criterion to determine the size of the mascon areas. The mascon size is usually chosen in a subjective manner which hampers the objective application of different mascon solutions. In view of these challenges, two main questions are addressed in this study: i) what kind of modifications should be made in computation scheme of the mascon solution if equiangular grids are used to account for different areas of the grid patches, and ii) in case of non-equiangular solutions, how to define an objective criterion for the patch sizes based on the resolution of both the observation and the signal of interest. We investigate the performance of the high-resolution mascon-based approach, proposed by Abedini et al. [2021], which uses GRACE-like observations similar to level-1 data for a period of one month over the Greenland region. Two main practical issues are studied on the estimation of the surface density changes as follows. First, we show that for equiangular grids, the area of the patches should be accounted for in the regularization by introducing area-affected weights for the unknown parameters. We investigate the effect of three different area-affected weighting strategies on the derived solution. Secondly in order to obtain proper size for the patches, a novel approach is presented to investigate the performance of the mascon solution using the analysis of the resolution matrix entries. The proposed resolution analysis is used to obtain the optimal patch size for the discretization of the area of interest. Based on the results, it is demonstrated that the minimum legible patch size in the Greenland area for the current settings of the GRACE observations is 0.5 degree in the NS direction and a latitude-adaptive grid-size rather than equiangular grids at high latitude regions in the EW direction.

Localization Approach of Damage in Welded Joint Based on Acoustic Emission Beamforming

2014 ◽  
Author(s):  
Denghong Xiao ◽  
Tian He ◽  
Xiandong Liu ◽  
Yingchun Shan
Keyword(s):  
Acoustic Emission ◽  
Welded Joints ◽  
Welded Joint ◽  
Steel Tube ◽  
Area Of Interest ◽  
Novel Approach ◽  
Line Array ◽  
The Cost ◽  
Localization Approach ◽  
Ae Signals

A novel approach of locating damage in welded joints is proposed based on acoustic emission (AE) beamforming, which is particularly applicable to complex plate-like structures. First, five AE sensors used to obtain AE signals generated from damage are distributed on the surface of the structure in a uniform line array. Then the beamforming method is adopted to detect the weld joints in the area of interest rather than all the points of the whole structure, and to determine the location and obtain information of AE sources. In order to study the ability of the proposed method more comprehensively, a rectangular steel tube with welded joints is taken for the pencil-lead-broken test. The localization results indicate that the proposed localization approach can effectively localize the failure welded joints. This improvement greatly reduces the cost of computation and also improves the efficiency of localization work compared with the traditional beamforming.

OP151 Weathering The Development To Adoption Storm: NICE Safe Harbors

2018 ◽  
Vol 34 (S1) ◽  
pp. 55-55
Author(s):  
Fay McCracken ◽  
Carla Deakin
Keyword(s):  
Healthcare System ◽  
Market Access ◽  
Life Sciences ◽  
Safe Harbor ◽  
Trade Associations ◽  
Safe Environment ◽  
Area Of Interest ◽  
Novel Approach ◽  
The Uk ◽  
The Impact

Introduction:Getting technologies adopted in the UK healthcare system can be time-consuming and complex. The National Institute for Health and Care Excellence Office for Market Access (NICE OMA) has developed a novel approach to enable greater and more coordinated dialogue between life sciences companies and healthcare system stakeholders on market access issues.Methods:When establishing NICE OMA, interactions were carried out with life sciences trade associations and key healthcare system stakeholders to explore challenges in market access landscape. Feedback highlighted that dialogue with NICE and other stakeholders is often limited and occurs in high-risk situations; indicating a need for greater and more coordinated dialogue between industry and multiple healthcare system stakeholders outside of formal processes.Results:The approach developed is a safe harbor engagement framework which enables NICE OMA to facilitate interaction between life sciences companies and key healthcare system stakeholders; this collaborative approach promotes shared understanding of aspects that will allow innovative technologies to reach patients faster. It brings together multiple organizations in a safe environment where ideas can be exchanged between participants, allowing organizations to think beyond their own area of interest and to work collaboratively. Companies have used the engagement framework flexibly to engage at different stages along the development to adoption journey. Feedback indicates that companies have benefitted from channeling discussions through NICE to bring together key leaders from different organizations, as well as the neutral facilitation of discussions. Healthcare system partners have gained insights/knowledge that hadn't been apparent beforehand. Patient and clinical representatives have appreciated the opportunity to provide views to a broad range of stakeholders often early in the development of the technology.Conclusions:The NICE OMA safe harbor engagement framework has been well-received to date. Further feedback will be sought to understand the impact in helping to optimize the market access journey.

scholarly journals Reliability, Availability and Maintainability Analysis for Grid-Connected Solar Photovoltaic Systems

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1213 ◽  
Author(s):  
A. Sayed ◽  
M. El-Shimy ◽  
M. El-Metwally ◽  
M. Elshahed
Keyword(s):  
Block Diagram ◽  
Solar Photovoltaic ◽  
Solar Pv ◽  
Pv System ◽  
Safety Issues ◽  
Pv Systems ◽  
Area Of Interest ◽  
Novel Approach ◽  
Maintainability Analysis ◽  
Ram Analysis

Recently, solar power generation is significantly contributed to growing renewable sources of electricity all over the world. The reliability and availability improvement of solar photovoltaic (PV) systems has become a critical area of interest for researchers. Reliability, availability, and maintainability (RAM) is an engineering tool used to address operational and safety issues of systems. It aims to identify the weakest areas of a system which will improve the overall system reliability. In this paper, RAM analysis of grid-connected solar-PV system is presented. Elaborate RAM analysis of these systems is presented starting from the sub-assembly level to the subsystem level, then the overall system. Further, an improved Reliability Block Diagram is presented to estimate the RAM performance of seven practical grid-connected solar-PV systems. The required input data are obtained from worldwide databases of failures, and repair of various subassemblies comprising various meteorological conditions. A novel approach is also presented in order to estimate the best probability density function for each sub-assembly. The monitoring of the critical subassemblies of a PV system will increase the possibility not only for improving the availability of the system, but also to optimize the maintenance costs. Additionally, it will inform the operators about the status of the various subsystems of the system.

A novel approach to the resolution analysis of geophysical inversion

2004 ◽  
Author(s):  
Michael S. Zhdanov ◽  
Ekaterina Tolstaya
Keyword(s):  
Geophysical Inversion ◽  
Novel Approach ◽  
Resolution Analysis

GRACE-FO accelerometer data recovery within ITSG-Grace2018 data processing

2020 ◽  
Author(s):  
Saniya Behzadpour ◽  
Torsten Mayer-Gürr ◽  
Andreas Kvas ◽  
Sandro Krauss ◽  
Sebastian Strasser ◽  
...  
Keyword(s):  
Gravitational Force ◽  
State Of The Art ◽  
Data Recovery ◽  
Force Model ◽  
Accelerometer Data ◽  
New Approach ◽  
Gravitational Forces ◽  
Gravity Field Recovery ◽  
Novel Approach ◽  
Gravity Recovery

<p>In GRACE-FO (Gravity Recovery and Climate Experiment Follow-on) mission, similar to its predecessor GRACE, the twin satellites are equipped with three-axis accelerometers, measuring the non-gravitational forces. After one month in orbit, the GRACE-D accelerometer data degraded and its measurements were replaced by synthetic accelerometer data, the so-called transplant data, officially generated by the Jet Propulsion Laboratory (JPL). The transplant data was derived from the GRACE-C accelerometer measurements, by applying a time and attitude corrections and adding model-based residual accelerations due to thruster firings on GRACE-D.</p><p>For the ITSG-Grace2018 GRACE-FO release, the gravity field recovery is based on the use of in-house Level-1B accelerometer data (ACT1B) using the provided Level-1A data products. In this work, we present a novel approach to recover the ACT1B data by (a) implementing the state-of-the-art non-gravitational force models and (b) applying additional force model corrections.</p><p>The preliminary results show the improved ACT1B data not only contributed to a noise reduction but also improved the estimates of the C20 and C30 coefficients. We show that the offset between SLR (Satellite Laser Ranging) and GRACE-FO derived C20 and C30 time series can be reduced remarkably by the use of the new accelerometer product, demonstrating the merit of this new approach.</p>

scholarly journals Identification of Unknown Parameters and Orders via Cuckoo Search Oriented Statistically by Differential Evolution for Noncommensurate Fractional-Order Chaotic Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-19 ◽  
Author(s):  
Fei Gao ◽  
Xue-Jing Lee ◽  
Heng-qing Tong ◽  
Feng-xia Fei ◽  
Hua-ling Zhao
Keyword(s):  
Differential Evolution ◽  
Fractional Order ◽  
Chaotic Systems ◽  
Cuckoo Search ◽  
Unknown Parameters ◽  
Independent Variables ◽  
Novel Approach ◽  
Proper Translation ◽  
Fractional Orders ◽  
Identification Mechanism

In this paper, a non-Lyapunov novel approach is proposed to estimate the unknown parameters and orders together for noncommensurate and hyper fractional chaotic systems based on cuckoo search oriented statistically by the differential evolution (CSODE). Firstly, a novel Gaos’ mathematical model is proposed and analyzed in three submodels, not only for the unknown orders and parameters’ identification but also for systems’ reconstruction of fractional chaos systems with time delays or not. Then the problems of fractional-order chaos’ identification are converted into a multiple modal nonnegative functions’ minimization through a proper translation, which takes fractional-orders and parameters as its particular independent variables. And the objective is to find the best combinations of fractional-orders and systematic parameters of fractional order chaotic systems as special independent variables such that the objective function is minimized. Simulations are done to estimate a series of noncommensurate and hyper fractional chaotic systems with the new approaches based on CSODE, the cuckoo search, and Genetic Algorithm, respectively. The experiments’ results show that the proposed identification mechanism based on CSODE for fractional orders and parameters is a successful method for fractional-order chaotic systems, with the advantages of high precision and robustness.

Load Identification Through Wavelet Parameterization

2001 ◽  
Author(s):  
T. Patrik Nordberg
Keyword(s):  
A Priori ◽  
Linear Optimization ◽  
Unknown Parameters ◽  
The Road ◽  
Novel Approach ◽  
Road Profile ◽  
Simulation Error ◽  
Load Location ◽  
And Performance ◽  
Error Method

Abstract A novel approach based on a simulation error method using a wavelet parameterization is assessed. The present study focuses on the case where the load location is known a priori as it is for the interaction between the road profile and the tyre patch for an automotive vehicle. The proposed method is a time domain technique and the resulting inverse problem is discussed from the viewpoint of two different parameterization approaches. One approach concerns Fourier coefficients and the other advocates the use of wavelet coefficients. The discretized road profile is parameterized into coefficients which greatly reduces the number of unknown parameters in the resulting non-linear optimization problem. Sensor locations are chosen in accordance with the concept of identifiability. Finally, a numerical five degree-of-freedom system illustrates the applicability and performance of the method.

247 LAPAROSCOPIC INTRAGASTRIC SUBMUCOSAL DISSECTION FOR EARLY GASTRIC CANCER: A VIDEO OF THE OXFORD APPROACH

2020 ◽  
Vol 33 (Supplement_1) ◽  
Author(s):  
S Mastoridis ◽  
P Chana ◽  
B Sgromo
Keyword(s):  
Case Series ◽  
Laparoscopic Approach ◽  
Posterior Wall ◽  
Late Complications ◽  
Effective Intervention ◽  
Gastric Cancers ◽  
Submucosal Dissection ◽  
Area Of Interest ◽  
Novel Approach ◽  
Lesser Curvature

Abstract   Laparoscopic intragastric submucosal dissection (LISD) is a novel approach to the resection of early gastric cancers not amenable to conventional gastroscopic approaches. The technique permits favourable access to lesions situated high on the posterior wall or lesser curvature of the stomach, enables en-block resection of large areas of tissue, and can prevent the need for formal gastrectomy. Using intraoperative video capture, we demonstrate our approach to LISD, and describe our peri-operative and long-term outcomes. Methods Six cases were identified as suitable for LISD by multidisciplinary team panel following EUS assessment and employing locally developed inclusion criteria. As demonstrated by video tutorial, a 3-port laparoscopic approach to the stomach was undertaken and gastrotomies performed to enable port insertion into the stomach. Following establishment of stable pneumogastrium, the area of interest was circumferentially marked with cautery and submucosal colloid injection performed to provide a cushion in the plane of dissection. Resection was completed using cautery hook, and intracorporeal suture closure of gastrotomies performed. Measures were taken to ensure correct orientation of resected specimens prior to fixation. Results Four male and two female patients (median age 74.5 years) sequentially underwent LISD, with complete curative excision confirmed histologically in 5 cases. In one case, a positive deep margin necessitated completion total gastrectomy, later confirmed to be T0 resection. No immediate or late complications, including haemorrhage, perforation or stenosis, occurred in these cases. Conclusion In this, the largest United Kingdom case series, LISD is shown to be a safe and effective intervention for the treatment of early gastric cancers in selected patients having undergone appropriate mapping endoscopy and deemed not to be amenable for endoscopic mucosal resection. Its application can serve as route to avoid formal gastrectomy and the associated morbidity. Video https://www.dropbox.com/s/nqlp7b9v64z56z8/Low.mp4?dl=0 This video demonstrates a novel approach to the resection of early gastric cancers not amenable to conventional gastroscopic approaches. Laparoscopic intragastric submucosal dissection (LISD) involves 3-port laparoscopy and intragastric port passage via gastrotomies. Stable pneumogastrium is performed and the field circumferentially marked by cautery. Submucosal colloid injection aids dissection. Tumour resection is completed by cautery and specimens removed via ports. Of 6 cases performed in Oxford, complete curative excision was confirmed histologically in 5, with 1 necessitating completion gastrectomy later confirmed to be T0 resection. No immediate or late complications were encountered. LISD is a safe and effective intervention which permits favourable access to lesions situated high on the posterior wall or lesser curvature of the stomach, enables en-block resection of large areas, and can prevent the need for gastrectomy.

scholarly journals FUSION OF LOCATION FINGERPRINTING AND TRILATERATION BASED ON THE EXAMPLE OF DIFFERENTIAL WI-FI POSITIONING

2017 ◽  
Vol IV-2/W4 ◽  
pp. 377-384 ◽  
Author(s):  
G. Retscher
Keyword(s):  
Low Cost ◽  
Mobile User ◽  
Reference Station ◽  
Raspberry Pi ◽  
Indoor Environments ◽  
Differential Gps ◽  
Area Of Interest ◽  
Location Fingerprinting ◽  
Novel Approach ◽  
Interest Differential

Positioning of mobile users in indoor environments with Wireless Fidelity (Wi-Fi) has become very popular whereby location fingerprinting and trilateration are the most commonly employed methods. In both the received signal strength (RSS) of the surrounding access points (APs) are scanned and used to estimate the user’s position. Within the scope of this study the advantageous qualities of both methods are identified and selected to benefit their combination. By a fusion of these technologies a higher performance for Wi-Fi positioning is achievable. For that purpose, a novel approach based on the well-known Differential GPS (DGPS) principle of operation is developed and applied. This approach for user localization and tracking is termed Differential Wi-Fi (DWi-Fi) by analogy with DGPS. From reference stations deployed in the area of interest differential measurement corrections are derived and applied at the mobile user side. Hence, range or coordinate corrections can be estimated from a network of reference station observations as it is done in common CORS GNSS networks. A low-cost realization with Raspberry Pi units is employed for these reference stations. These units serve at the same time as APs broadcasting Wi-Fi signals as well as reference stations scanning the receivable Wi-Fi signals of the surrounding APs. As the RSS measurements are carried out continuously at the reference stations dynamically changing maps of RSS distributions, so-called radio maps, are derived. Similar as in location fingerprinting this radio maps represent the RSS fingerprints at certain locations. From the areal modelling of the correction parameters in combination with the dynamically updated radio maps the location of the user can be estimated in real-time. The novel approach is presented and its performance demonstrated in this paper.

Station Keeping Adaptive Control of a Boat With Twin Gasoline Outboard Motors: Synthesis, Simulation and Sea-Trials

2011 ◽  
Author(s):  
Aaron Fisher ◽  
James VanZwieten ◽  
Nikolaos I. Xiros
Keyword(s):  
Adaptive Control ◽  
Gain Control ◽  
Control Algorithms ◽  
Station Keeping ◽  
Ocean Energy ◽  
Small Vessels ◽  
Area Of Interest ◽  
Novel Approach ◽  
Energy Projects ◽  
Automatic Station

There are increasingly more areas in which automatic station keeping technology can be of great benefit for small boat operators. This trend stems from technological advances that allow for smaller and more portable instrumentation and gear, bringing down the necessary size of vessels, which ultimately reduces cost. However, smaller vessels find themselves more adversely affected by sea conditions and have limited thrusting capabilities. Currently a skilled captain is needed on these small vessels to hold position over the area of interest in the presence of wind, wave, and current disturbances. Implementation of an automatic station keeping controller would free the captain from constantly monitoring the navigational instruments, to more closely supervise onboard operations and keep watch for other vessels in the area. Station keeping technology is currently being perused by Florida Atlantic University to enhance the ability of its 33ft boat to make oceanographic measurements in the Gulf Stream pertinent to its ocean energy projects. Such ocean energy projects require water velocity and temperature measurements at specific locations as part of the efforts for assessment of the hydrokinetic and ocean thermal resource. This technology is also a pivotal part of the sea basing goal currently being pursued by the Navy, which would allow vessels to stay in close but acceptable proximity to one another. The ability to hold position over a desired location can also have many additional uses such as for fishing, conducting surveys, deploying instruments, and transferring cargo or personnel. This text presents a novel approach for doing station keeping, as thus far a system for station keeping on small vessels using only tied twin outboard motors has not been developed and applied to an ocean going vessel by industry or academia. These controllers have been developed using multiple fixed-gain and adaptive control algorithms. Using a custom sensor and control system mounted onboard the test vessel; navigational measurements are used to adjust the throttles and engine angle using these developed algorithms. The performance of each of these controllers has been quantified using both numerical simulations and at sea testing. Using the results from these tests, initial comparisons have been made that show the advantages gained by using adaptive control algorithms instead of fixed-gain control.

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