scholarly journals Analysis of RDSS Positioning Performance under Elevation Constraints

2018 ◽  
Vol 176 ◽  
pp. 01040
Author(s):  
Yao Fan ◽  
Wenxiang Liu ◽  
Wei Xiao ◽  
Guangfu Sun
Keyword(s):  
Estimation Methods ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Accuracy Estimation ◽  
Dilution Of Precision ◽  
Traditional Algorithm ◽  
Ranging Error ◽  
The Difference ◽  
The Impact ◽  
Prediction Capability

When using RDSS positioning under elevation constraints, traditional positioning accuracy estimation methods may not reflect the impact of satellite ranging error and elevation error on positioning performance accurately. In order to evaluate RDSS positioning performance more accurately, the RDSS positioning principle is presented, and the weighted position dilution of precision (WPDOP) is used to replace the traditional algorithm. The positioning error calculated by WPDOP is closer to actual results, indicating better prediction capability of positioning performance. Under different elevation error conditions, the position dilution of precision (PDOP) distribution of the service area indicates that the difference between the two precision factors is mainly affected by the elevation error and latitude, while the influence of longitude is small.

scholarly journals Factor Graph-Assisted Distributed Cooperative Positioning Algorithm in the GNSS System

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3748 ◽  
Author(s):  
Chengkai Tang ◽  
Lingling Zhang ◽  
Yi Zhang ◽  
Houbing Song
Keyword(s):  
Smart Cities ◽  
Factor Graph ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Cooperative Positioning ◽  
Measured Range ◽  
Ranging Error ◽  
Positioning Algorithm ◽  
Range Error ◽  
Cooperative Nodes

The development of smart cities calls for improved accuracy in navigation and positioning services; due to the effects of satellite orbit error, ionospheric error, poor quality of navigation signals and so on, it is difficult for existing navigation technology to achieve further improvements in positioning accuracy. Distributed cooperative positioning technology can further improve the accuracy of navigation and positioning with existing GNSS (Global Navigation Satellite System) systems. However, the measured range error and the positioning error of the cooperative nodes exhibit larger reductions in positioning accuracy. In response to this question, this paper proposed a factor graph-aided distributed cooperative positioning algorithm. It establishes the confidence function of factor graphs theory with the ranging error and the positioning error of the coordinated nodes and then fuses the positioning information of the coordinated nodes by the confidence function. It can avoid the influence of positioning error and ranging error and improve the positioning accuracy of cooperative nodes. In the simulation part, the proposed algorithm is compared with a mainly coordinated positioning algorithm from four aspects: the measured range error, positioning error, convergence speed, and mutation error. The simulation results show that the proposed algorithm leads to a 30–60% improvement in positioning accuracy compared with other algorithms under the same measured range error and positioning error. The convergence rate and mutation error elimination times are only 1 / 5 to 1 / 3 of the other algorithms.

scholarly journals A Crook is a Crook . . . But is He Still a Crook Abroad? On the Effect of Immigration on Destination-Country Corruption

2015 ◽  
Vol 16 (4) ◽  
pp. 464-489 ◽  
Author(s):  
Eugen Dimant ◽  
Margarete Redlin ◽  
Tim Krieger
Keyword(s):  
Method Of Moments ◽  
Fixed Effects ◽  
Generalized Method Of Moments ◽  
Destination Country ◽  
Estimation Methods ◽  
Econometric Methodology ◽  
Migration Flows ◽  
The Difference ◽  
Method Of Moments Estimator ◽  
The Impact

AbstractThis paper analyzes the impact of migration on destination-country corruption levels. Capitalizing on a comprehensive dataset consisting of annual immigration stocks of OECD countries from 207 countries of origin for the period 1984-2008, we explore different channels through which corruption might migrate. We employ different estimation methods using fixed effects and Tobit regressions in order to validate our findings. Moreover, we also address the issue of endogeneity by using the Difference- Generalized Method of Moments estimator. Independent of the econometric methodology, we consistently find that while general migration has an insignificant effect on the destination country’s corruption level, immigration from corruption-ridden origin countries boosts corruption in the destination country. Our findings provide a more profound understanding of the socioeconomic implications associated with migration flows.

scholarly journals IMPLICATION OF ALTERNATIVE MINIMAL CLINICALLY IMPORTANT DIFFERENCE THRESHOLD ESTIMATION METHODS ON TECHNOLOGY ASSESSMENT

2016 ◽  
Vol 32 (6) ◽  
pp. 371-375 ◽  
Author(s):  
Diana Brixner ◽  
Eli O. Meltzer ◽  
Kellie Morland ◽  
Cathryn A. Carroll ◽  
Ullrich Munzel ◽  
...  
Keyword(s):  
Technology Assessment ◽  
Minimal Clinically Important Difference ◽  
Nasal Symptom ◽  
Healthcare Research ◽  
Estimation Methods ◽  
Difference Threshold ◽  
Threshold Estimation ◽  
Clinically Important Difference ◽  
The Difference ◽  
The Impact

Objectives: Various minimal clinically important difference (MCID) threshold estimation techniques have been applied to seasonal allergic rhinitis (SAR). The objectives of this study are to (i) assess the difference in magnitude of alternative SAR MCID threshold estimates and (ii) evaluate the impact of alternative MCID estimates on health technology assessment (HTA).Methods: Data describing change from baseline of the reflective Total Nasal Symptom Score (rTNSS) for four intranasal SAR treatments were obtained from United States Food and Drug Administration-approved prescribing information. Treatment effects were then compared with anchor-based MCID thresholds derived by Barnes et al. and thresholds obtained from an Agency for Healthcare Research and Quality (AHRQ) panel.Results: The change in rTNSS score from baseline, represented as the average of the twice-daily recorded scores of the rTNSS, was -2.1 (p < .001) for azelastine hydrochloride 0.10%, 1.35 (p = .014) for ciclesonide, and -1.47 (p < .001) for fluticasone furoate. The change in the rTNSS score from baseline, represented by sum of the AM and PM score, was -2.7 for MP-AzeFlu (p < .001). The rTNSS change from baseline for each product was compared with anchor-based MCID threshold and the AHRQ panel estimates. Comparison of the observed treatment effect to the anchor-based and AHRQ panel MCID thresholds results in different conclusions, with clinically important differences being inferred when anchor-based estimates serve as the reference point.Conclusion: The AHRQ panel MCID threshold for the rTNSS was twelve times larger than the anchor-based estimates resulting in conflicting recommendations on whether different SAR treatments provide clinically meaningful benefit.

The Error Analysis of GPS-RTK Construction Stakeout

2013 ◽  
Vol 655-657 ◽  
pp. 1884-1888
Author(s):  
Jin Hong Xu ◽  
Ruo Li Yang ◽  
Bei Bei Zhang
Keyword(s):  
Error Analysis ◽  
Real Time ◽  
External Environment ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Gps Rtk ◽  
Satellite Signal ◽  
The Impact ◽  
Surveying And Mapping

GPS-RTK technology with real-time , high positioning accuracy and easy to operate features, is widely used in the filed of surveying and mapping; With the improvement of RTK technology, the initialize speed , results accuracy and reliability of the RTK survey will be increasingly higher.Due to the impact of the satellite signal and the external environment, the deviation of the RTK positioning and the lack of necessary checking conditions in RTK surveying, this paper will do some researches and analyses about RTK positioning error to serve the Survey and Mapping Engineering better.

A Comparative Analysis of Shipping Emissions Estimation Methodologies and their Applicability

2013 ◽  
Vol 734-737 ◽  
pp. 3042-3047
Author(s):  
Wei Xiao ◽  
Qing Qi Wei
Keyword(s):  
Comparative Analysis ◽  
Estimation Method ◽  
Air Pollutant ◽  
Pollutant Emissions ◽  
Estimation Methods ◽  
Emissions Inventory ◽  
Specific Approach ◽  
The Difference ◽  
The Impact ◽  
Ship Movement

The shipping emissions estimation method is the premise and basis of making shipping emissions inventory, assessing the impact of shipping emissions, and promoting the work of energy saving and emissions reduction in transportation industry. The article analyzed the three main kinds of current representative shipping emissions estimation methods, i.e. simplified methodology and detailed methodology for estimating air pollutant emissions from ships presented by Techne Consulting, Tier1 and Tier2 methods from IPCC, and default approach, technology specific approach and ship movement methodology proposed by EMEP. Based on a comparative analysis of the characteristics of these estimation methods and their applicability, it was shown that: (1) the three kinds of methods from Techne Consulting, IPCC and EMEP are essentially the same, that is the emission equals to the product of the level of activities and emission factors, the difference lies in the level of detail of the activities are broken down; (2) the three shipping emissions calculation methods proposed by EMEP can be considered as the comprehensive and representative method, the default approach is a top-down method, and the technology specific approach and ship movement methodology are bottom-up approaches; (3) different methods have different applicability, the default approach proposed by EMEP is recommended to estimate CO2, SO2 emissions from shipping, and the technology specific approach and ship movement methodology are suitable for estimating the emissions of the other pollutants.

scholarly journals Improved RSSI Positioning Algorithm for Coal Mine Underground Locomotive

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Bin Ge ◽  
Kai Wang ◽  
Jianghong Han ◽  
Bao Zhao
Keyword(s):  
Coal Mine ◽  
Gaussian Model ◽  
Correction Method ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Positioning Errors ◽  
Weighted Model ◽  
The Difference ◽  
Positioning Algorithm ◽  
Received Signal Strength Indication

Aiming at the large positioning errors of traditional coal mine underground locomotive, an improved received signal strength indication (RSSI) positioning algorithm for coal mine underground locomotive was proposed. The RSSI value fluctuates heavily due to the poor environment of coal mine underground. The nodes with larger RSSI value corrected by Gaussian-weighted model were selected as beacon nodes. In order to reduce the positioning error further, the estimated positions of the locomotives were corrected by the weighted distance correction method. The difference between actual position and estimated position of beacon node was regarded as the positioning error and was given a corresponding weight. The results of simulation show that the positioning accuracy of Gaussian-weighted model is better than statistical average model and Gaussian model and it has a high positioning accuracy after correcting positioning error correction. In the 10 m of communication range, positioning error can be maintained at 0.5 m.

scholarly journals Effects of Selective Availability on GPS Positioning Accuracy

2002 ◽  
Vol 26 (3) ◽  
pp. 140-145 ◽  
Author(s):  
C.J. Liu
Keyword(s):  
Small Region ◽  
Data Set ◽  
Positioning Accuracy ◽  
Gps Positioning ◽  
Free Data ◽  
Satellite Geometry ◽  
The Difference ◽  
Gps Accuracy ◽  
The Impact ◽  
Gps Observations

Abstract Deactivation of selective availability (SA) is expected to provide improvement in Global Positioning System (GPS) accuracy, and recent reports showed such improvements were realized immediately. However, most forestry GPS observations are made in subcanopy environments in which a GPS receiver's antenna can only receive GPS signals from a small region of the sky due to obstructions. Consequently, the satellite geometry will be poor, and position accuracy will suffer. Thus, there is a need to understand the impact of SA removal on positioning accuracy in high-PDOP subcanopy observations. This study found that it is difficult to approach the destination when GPS navigation is adversely influenced by SA accuracy degradation. When GPS positioning is performed after SA deactivation, a GPS observer can walk directly to the intended destination under thick tree canopies. Results also indicated that the horizontal accuracy is 73.3 m at the 95% probability level in the SA-degraded data set and 8.3 m in the SA-free data set. Further data analysis indicated that HDOPs (Langley 1999) recorded in the SA-on and the SA-off periods are not statistically significantly different. This suggests that a major portion of the difference in horizontal accuracies between SA-degraded and SA-free GPS observations can be attributed to difficulties in approaching the destination when SA is active. South. J. Appl. For. 26(3):140–145.

scholarly journals The Impact of Price and Non-Price Factors on Area Allocated to Oilseeds in India: An Application of ARDL Model

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Debasis Mithiya ◽  
Simanti Bandyopadhyay ◽  
Kumarjit Mandal
Keyword(s):  
Dynamic Panel Data ◽  
Estimation Methods ◽  
Ardl Model ◽  
Dynamic Relationship ◽  
Pooled Mean Group ◽  
Long Run ◽  
Equilibrium Relationship ◽  
The Difference ◽  
The Impact ◽  
Long Run Equilibrium

The study attempts to investigate the dynamic relationship between acreage allocation of oilseeds and price (own price and prices of competitive crops) and also search for the link between area allocation and other non-price factors including productivity, irrigation, rainfall, technology and a policy-making variable (economic liberalization). The dynamic panel data for the year 1976-77 to 2017-18 have been used in the analysis. The study has used the autoregressive distributive lag (ARDL) model to understand the relationship between the dependent and the independent variables and to investigate the long-run equilibrium relationship between them. To estimate the model, both PMG (Pooled Mean Group) and MG (Mean group) estimation methods have been used. The Hausman test has been conducted to see the difference between the PMG and the MG results. The outcomes show that PMG serves as an efficient estimator here. The error correction terms are negative and significant. The results show strong evidence of area allocation towards oilseed crops, indicate a strong co-integration among their determinants in the long run. The ARDL results indicate that the speed of adjustment towards long-run equilibrium varies from 14.8 to 40.6 percent.

The Weighted Multilateral Positioning Algorithm Based on Time Reversal Ranging

2014 ◽  
Vol 644-650 ◽  
pp. 1464-1469
Author(s):  
Zheng Zhang ◽  
Xing Peng Tao ◽  
Lun Zeng ◽  
Chan Wang
Keyword(s):  
Time Reversal ◽  
Wireless Sensor ◽  
Positioning Error ◽  
Complex Environments ◽  
Complex Environment ◽  
General Applicability ◽  
Positioning Accuracy ◽  
Key Technology ◽  
Ranging Error ◽  
Positioning Algorithm

Indoor node positioning is a key technology in wireless sensor network but the general indoor nodes positioning algorithm is difficult to meet the precision positioning requirements due to the indoor complex environment such as multilateral positioning algorithm based on RSSI ranging. The weighted multilateral positioning algorithm is proposed based on time reversal ranging to solve the problem. We simulate within 50m*50m area, the experimental results show that the ranging error is less than 1%. The maximum positioning error is less than 0.6m. Compared with general positioning algorithm, it can improve the positioning accuracy greatly in complex environments and has general applicability.

scholarly journals Time synchronization requirement of global navigation satellite system augmentation system based on pseudolite

2019 ◽  
Vol 52 (3-4) ◽  
pp. 303-313 ◽  
Author(s):  
Chao Ma ◽  
Jun Yang ◽  
Jianyun Chen ◽  
Yinyin Tang
Keyword(s):  
Time Synchronization ◽  
Vertical Direction ◽  
Civil Aviation ◽  
Engineering Practice ◽  
Navigation Satellite ◽  
Positioning Accuracy ◽  
Dilution Of Precision ◽  
Global Navigation ◽  
Global Navigation Satellite ◽  
The Impact

Global navigation satellite systems are widely used across the world because of their continuous/all-weather, global coverage, and high precision positioning. But, three-dimensional positioning accuracy, especially in the vertical direction, remains insufficient because of the geometric distribution of satellites. This is especially true for air-borne objects such as unmanned aerial vehicles, civil aviation devices, and missiles. To solve this problem, we adopt a satellite-ground joint positioning system based on a pseudo-satellite (pseudolite). The introduction of ground pseudolites can significantly reduce the vertical dilution of precision and improve positioning accuracy. This method has been proposed in the 1980s. However, we have to ask a question, as long as we add a pseudolite, can the positioning accuracy be improved? The answer is no. Pseudolites can cause time synchronization problems with satellites, and the resulting timing errors of the pseudolite are converted into pseudorange errors, reducing accuracy. Here, we seek to evaluate the impact of the reduced vertical dilution of precision and the increased range errors associated with the introduction of a pseudolite on the ground. We derive a mathematical formula to explain this relationship. We conclude that when the satellite range error and the change in the position dilution of precision associated with a pseudolite are known, we can calculate an approximate limit for the pseudolite timing accuracy to ensure that the use of the pseudolite improves the positioning accuracy. This work should be of great value in guiding engineering practice.

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