scholarly journals Spatially Heterogeneous Land Surface Deformation Data Fusion Method Based on an Enhanced Spatio-Temporal Random Effect Model

2019 ◽  
Vol 11 (9) ◽  
pp. 1084 ◽  
Author(s):  
Qiang Shi ◽  
Wujiao Dai ◽  
Rock Santerre ◽  
Zhiwei Li ◽  
Ning Liu
Keyword(s):  
Los Angeles ◽  
Spatial Heterogeneity ◽  
Land Surface ◽  
Surface Deformation ◽  
Random Effect ◽  
Random Effect Model ◽  
Fusion Method ◽  
Fusion Model ◽  
Spatio Temporal ◽  
Monitoring Area

The spatio-temporal random effect (STRE) model, a type of spatio-temporal Kalman filter model, can be used for the fusion of the Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data to generate high spatio-temporal resolution deformation series, assuming that the land deformation is spatially homogeneous in the monitoring area. However, when there are multiple deformation sources in the monitoring area, complex spatial heterogeneity will appear. To improve the fusion accuracy, we propose an enhanced STRE fusion method (eSTRE) by taking spatial heterogeneity into consideration. This new method integrates the spatial heterogeneity constraints in the STRE model by constructing extra-constrained spatial bases for the heterogeneous area. The effectiveness of this method is verified by using simulated data and real land surface deformation data. The results show that eSTRE can reduce the root mean square (RMS) of InSAR interpolation results by 14% and 23% on average for a simulation experiment and Los Angeles experiment, respectively, indicating that the new proposed method (eSTRE) is substantially better than the previous STRE fusion model.

scholarly journals A Comprehensive and Automated Fusion Method: The Enhanced Flexible Spatiotemporal DAta Fusion Model for Monitoring Dynamic Changes of Land Surface

2019 ◽  
Vol 9 (18) ◽  
pp. 3693 ◽  
Author(s):  
Shi ◽  
Wang ◽  
Zhang ◽  
Liang ◽  
Niu ◽  
...  
Keyword(s):  
Data Fusion ◽  
Land Surface ◽  
Abrupt Change ◽  
Spatiotemporal Data ◽  
Gradual Change ◽  
Fusion Method ◽  
Fusion Model ◽  
Dynamic Changes ◽  
Change Events ◽  
Fusion Methods

Spatiotemporal fusion methods provide an effective way to generate both high temporal and high spatial resolution data for monitoring dynamic changes of land surface. But existing fusion methods face two main challenges of monitoring the abrupt change events and accurately preserving the spatial details of objects. The Flexible Spatiotemporal DAta Fusion method (FSDAF) was proposed, which can monitor the abrupt change events, but its predicted images lacked intra-class variability and spatial details. To overcome the above limitations, this study proposed a comprehensive and automated fusion method, the Enhanced FSDAF (EFSDAF) method and tested it for Landsat–MODIS image fusion. Compared with FSDAF, the EFSDAF has the following strengths: (1) it considers the mixed pixels phenomenon of a Landsat image, and the predicted images by EFSDAF have more intra-class variability and spatial details; (2) it adjusts the differences between Landsat images and MODIS images; and (3) it improves the fusion accuracy in the abrupt change area by introducing a new residual index (RI). Vegetation phenology and flood events were selected to evaluate the performance of EFSDAF. Its performance was compared with the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM), the Spatial and Temporal Reflectance Unmixing Model (STRUM), and FSDAF. Results show that EFSDAF can monitor the changes of vegetation (gradual change) and flood (abrupt change), and the fusion images by EFSDAF are the best from both visual and quantitative evaluations. More importantly, EFSDAF can accurately generate the spatial details of the object and has strong robustness. Due to the above advantages of EFSDAF, it has great potential to monitor long-term dynamic changes of land surface.

scholarly journals Localized Subsidence Zones in Gävle City Detected by Sentinel-1 PSI and Leveling Data

2020 ◽  
Vol 12 (16) ◽  
pp. 2629
Author(s):  
Nureldin A. A. Gido ◽  
Mohammad Bagherbandi ◽  
Faramarz Nilfouroushan
Keyword(s):  
Land Surface ◽  
Urban Areas ◽  
Surface Deformation ◽  
Subsurface Layer ◽  
Ground Surface ◽  
Surface Subsidence ◽  
Economic Consequences ◽  
Persistent Scatterer Interferometry ◽  
Persistent Scatterer ◽  
Spatio Temporal

Among different sets of constraints and hazards that have to be considered in the management of cities and land use, land surface subsidence is one of the important issues that can lead to many problems, and its economic consequences cannot be ignored. In this study, the ground surface deformation of Gävle city in Sweden is investigated using the Persistent Scatterer Interferometry (PSI) technique as well as analyzing the historical leveling data. The PSI technique is used to map the location of hazard zones and their ongoing subsidence rate. Two ascending and descending Sentinel-1 datasets, collected between January 2015 and May 2020, covering the Gävle city, were processed and analyzed. In addition, a long record of a leveling dataset, covering the period from 1974 to 2019, was used to detect the rate of subsidence in some locations which were not reported before. Our PSI analysis reveals that the center of Gävle is relatively stable with minor deformation ranged between −2 ± 0.5 mm/yr to +2 ± 0.5 mm/yr in vertical and east–west components. However, the land surface toward the northeast of the city is relatively subsiding with a higher annual rate of up to −6 ± 0.46 mm/yr. The comparison at sparse locations shows a close agreement between the subsidence rates obtained from precise leveling and PSI results. The regional quaternary deposits map was overlaid with PSI results and it shows the subsidence areas are mostly located in zones where the subsurface layer is marked by artificial fill materials. The knowledge of the spatio-temporal extents of land surface subsidence for undergoing urban areas can help to develop and establish models to mitigate hazards associated with such land settlement.

Mapping Groundwater Fluctuations in the Coastal Los Angeles Basin by Seismic Interferometry

2021 ◽  
Author(s):  
Shujuan Mao ◽  
Michel Campillo ◽  
Robert van der Hilst ◽  
Albanne Lecointre
Keyword(s):  
Los Angeles ◽  
Spatial Patterns ◽  
Surface Deformation ◽  
Seismic Velocity ◽  
Real Data ◽  
Coda Wave ◽  
Central Basin ◽  
Imaging Protocol ◽  
Groundwater Fluctuations ◽  
Spatio Temporal

<p>Changes in crustal seismic velocity (d<em>v/v</em>) can be monitored continuously in time by interferometry of seismic ambient noise. This approach has been successfully employed to study temporal perturbations in stress fields, rock fractures, and fluids. Here we go one step further with this monitoring technique, by not only detecting the temporal changes but also imaging the inhomogeneous spatial distributions of d<em>v/v</em>. We implement the spatial imaging by leveraging travel-time shifts at successive lag times and solving inverse problems based on coda-wave sensitivity kernels. We then use these space-time observations of d<em>v/v </em>to investigate the groundwater fluctuations in the Coastal Los Angeles (LA) Basin during 2000-2020. Imaging of d<em>v/v</em> demonstrates the spatial patterns of groundwater variations: Seasonal changes are most pronounced within confined zones in Santa Ana Basin and LA Central Basin, whereas the long-term changes extend to a broader area including the unconfined forebay. We further compare d<em>v/v</em> observations with InSAR measurements and find strongly consistent spatial patterns. Compared with surface deformation measurements, d<em>v/v</em> additionally help to characterize the depths of several aquifers in the study area. This real-data application substantiates the validity of our d<em>v/v</em> imaging protocol, and shows the promise of using spatio-temporal d<em>v/v</em> observations to monitor surficial hydrological processes.</p>

scholarly journals Scaling Effect of Fused ASTER-MODIS Land Surface Temperature in an Urban Environment

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4058 ◽  
Author(s):  
Hua Liu ◽  
Qihao Weng
Keyword(s):  
Los Angeles ◽  
Image Fusion ◽  
Land Surface ◽  
Nearest Neighbor ◽  
Thermal Emission ◽  
Thermal Studies ◽  
Urban Heat Islands ◽  
Bilinear Interpolation ◽  
Fusion Model ◽  
Resampling Methods

There is limited research in land surface temperatures (LST) simulation using image fusion techniques, especially studies addressing the downscaling effect of LST image fusion. LST simulation and associated downscaling effect can potentially benefit the thermal studies requiring both high spatial and temporal resolutions. This study simulated LSTs based on observed Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Terra Moderate Resolution Imaging Spectroradiometer (MODIS) LST imagery with Spatial and Temporal Adaptive Reflectance Fusion Model, and investigated the downscaling effect of LST image fusion at 15, 30, 60, 90, 120, 250, 500, and 1000 m spatial resolutions. The study area partially covered the City of Los Angeles, California, USA, and surrounding areas. The reference images (observed ASTER and MODIS LST imagery) were acquired on 04/03/2007 and 07/01/2007, with simulated LSTs produced for 4/28/2007. Three image resampling methods (Cubic Convolution, Bilinear Interpolation, and Nearest Neighbor) were used during the downscaling and upscaling processes, and the resulting LST simulations were compared. Results indicated that the observed ASTER LST and simulated ASTER LST images (date 04/28/2007, spatial resolution 90 m) had high agreement in terms of spatial variations and basic statistics based on a comparison between the observed and simulated ASTER LST maps. Urban developed lands possessed higher LSTs with lighter tones and mountainous areas showed dark tones with lower LSTs. The Cubic Convolution and Bilinear Interpolation resampling methods yielded better results over Nearest Neighbor resampling method across the scales from 15 to 1000 m. The simulated LSTs with image fusion can be used as valuable inputs in heat related studies that require frequent LST measurements with fine spatial resolutions, e.g., seasonal movements of urban heat islands, monthly energy budget assessment, and temperature-driven epidemiology. The observation of scale-independency of the proposed image fusion method can facilitate with image selections of LST studies at various locations.

Qualitative Research on Critical Issues In Halal Logistics

2013 ◽  
Vol 1 (2) ◽  
pp. 131 ◽  
Author(s):  
Mohamed Syazwan Ab Talib ◽  
Lim Rubin ◽  
Vincent Khor Zhengyi
Keyword(s):  
Capital Structure ◽  
Agency Theory ◽  
Random Effect ◽  
Random Effect Model ◽  
Order Theory ◽  
Specific Factor ◽  
Pecking Order ◽  
Pecking Order Theory ◽  
Corporate Financing ◽  
Financing Decision

This is a preliminary study developed to explore the determinants of capital structure of Shariah-compliant firms listed in Bursa Malaysia. This study is primarily motivated by the issue of the determinants still being inconclusive in the area of capital structure. The study is performed using the static models namely Pool Ordinary Least Square, Fixed Effect and Random Effect Model. Empirical analysis on the determinants reveals that country specific factor which is GDP and sector specific factor which is industry concentration are also significant in influencing the corporate financing decisions in this country along with firm specific factors such as efficiency, bankruptcy risk, profitability, tangibility, liquidity and size of the firm. The findings revealed that results are sensitive to models employed in the study. Nevertheless, the applicability of capital structure theories such as the trade-off theory, agency theory and pecking order theory diverge across sectors in Malaysia. The pecking order theory and agency theory are found to be the dominant theories governing the corporate financing decision in the country as well. It indicates strong evidence of hierarchy practised in firms’ financing decision. The finding on agency theory being dominant justifies the function of short-term debt as a controlling mechanism to mitigate the agency problem arises within firms across sectors. 

Analisis Pengaruh Kepemilikan Blockholder, Kepemilikan Manajerial, Kepemilikan Institusional, dan Komite Audit terhadap Nilai Perusahaan

2018 ◽  
Vol 2 (1) ◽  
pp. 96-121
Author(s):  
Iwan Wirawardhana ◽  
Meco Sitardja
Keyword(s):  
Firm Value ◽  
Audit Committee ◽  
Stock Exchange ◽  
Random Effect ◽  
Random Effect Model ◽  
Institutional Ownership ◽  
Managerial Ownership ◽  
Estimation Model ◽  
Effect Model ◽  
Positive Effect

The aim of this study is to analyse the effect of Blockholder Ownership, Managerial Ownership,Institutional Ownership, and Audit Committee towards Firm Value. The background of this research isthe agency theory and ownership theory. The population in this study are 46 property companies listedon the Indonesia Stock Exchange (IDX) for the period 2012-2016. By using purposive samplingtechnique, 35 companies are qualified as data samples. This research uses the random effect model asthe estimation model and multiple regression as the method of analysis. The results of this study showsthat Institutional Ownership has a positive effect on Firm Value. Meanwhile, Blockholder Ownership,Managerial Ownership, and Audit Committee have no effect on Firm Value. Moreover, the F-testimplies that the variables, blockholder ownership, managerial ownership, institutional ownership, andaudit committee, simultaneously influence firm value.

scholarly journals Prevalence and risk factors for antibiotic utilization in Chinese children

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shasha Guo ◽  
Qiang Sun ◽  
Xinyang Zhao ◽  
Liyan Shen ◽  
Xuemei Zhen
Keyword(s):  
Risk Factors ◽  
Meta Analysis ◽  
Random Effect ◽  
Random Effect Model ◽  
Healthcare Research ◽  
Chinese Children ◽  
Rural Setting ◽  
Antibiotic Prescribing ◽  
Antibiotic Utilization ◽  
At Home

Abstract Background Antibiotic resistance poses a significant threat to public health globally. Irrational utilization of antibiotics being one of the main reasons of antibiotic resistant. Children as a special group, there's more chance of getting infected. Although most of the infection is viral in etiology, antibiotics still are the most frequently prescribed medications for children. Therefore, high use of antibiotics among children raises concern about the appropriateness of antibiotic prescribing. This systematic review aims to measuring prevalence and risk factors for antibiotic utilization in children in China. Methods English and Chinese databases were searched to identify relevant studies evaluating the prevalence and risk factors for antibiotic utilization in Chinese children (0-18 years), which were published between 2010 and July 2020. A Meta-analysis of prevalence was performed using random effect model. The Agency for Healthcare Research and Quality (AHRQ) and modified Jadad score was used to assess risk of bias of studies. In addition, we explored the risk factors of antibiotic utilization in Chinese children using qualitative analysis. Results Of 10,075 studies identified, 98 eligible studies were included after excluded duplicated studies. A total of 79 studies reported prevalence and 42 studies reported risk factors for antibiotic utilization in children. The overall prevalence of antibiotic utilization among outpatients and inpatients were 63.8% (35 studies, 95% confidence interval (CI): 55.1-72.4%), and 81.3% (41 studies, 95% CI: 77.3-85.2%), respectively. In addition, the overall prevalence of caregiver’s self-medicating of antibiotics for children at home was 37.8% (4 studies, 95% CI: 7.9-67.6%). The high prevalence of antibiotics was associated with multiple factors, while lacking of skills and knowledge in both physicians and caregivers was the most recognized risk factor, caregivers put pressure on physicians to get antibiotics and self-medicating with antibiotics at home for children also were the main factors attributed to this issue. Conclusion The prevalence of antibiotic utilization in Chinese children is heavy both in hospitals and home. It is important for government to develop more effective strategies to improve the irrational use of antibiotic, especially in rural setting.

scholarly journals A meta-analysis comparing short-term weight and cardiometabolic changes between olanzapine/samidorphan and olanzapine

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manit Srisurapanont ◽  
Sirijit Suttajit ◽  
Surinporn Likhitsathian ◽  
Benchalak Maneeton ◽  
Narong Maneeton
Keyword(s):  
Weight Gain ◽  
Meta Analysis ◽  
Random Effect ◽  
Random Effect Model ◽  
Dropout Rates ◽  
Lower Percentage ◽  
Current Evidence ◽  
Weight Changes ◽  
Short Term ◽  
Short Term Treatment

AbstractThis study compared weight and cardiometabolic changes after short-term treatment of olanzapine/samidorphan and olanzapine. Eligible criteria for an included trial were ≤ 24 weeks, randomized controlled trials (RCTs) that compared olanzapine/samidorphan and olanzapine treatments in patients/healthy volunteers and reported weight or cardiometabolic outcomes. Three databases were searched on October 31, 2020. Primary outcomes included weight changes and all-cause dropout rates. Standardized mean differences (SMDs) and risk ratios (RRs) were computed and pooled using a random-effect model. This meta-analysis included four RCTs (n = 1195). The heterogeneous data revealed that weight changes were not significantly different between olanzapine/samidorphan and olanzapine groups (4 RCTs, SDM = − 0.19, 95% CI − 0.45 to 0.07, I2 = 75%). The whole-sample, pooled RR of all-cause dropout rates (4 RCTs, RR = 1.02, 95% CI 0.84 to 1.23, I2 = 0%) was not significant different between olanzapine/samidorphan and olanzapine groups. A lower percentage of males and a lower initial body mass index were associated with the greater effect of samidorphan in preventing olanzapine-induced weight gain. Current evidence is insufficient to support the use of samidorphan to prevent olanzapine-induced weight gain and olanzapine-induced cardiometabolic abnormalities. Samidorphan is well accepted by olanzapine-treated patients.

Sign in / Sign up

Export Citation Format

Share Document