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Biswajeet Pradhan - One of the best experts on this subject based on the ideXlab platform.
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gis based groundwater spring potential mapping using data mining boosted regression tree and probabilistic Frequency Ratio models in iran
geosciences 2017 Vol. 3 Pages 91-115, 2017Co-Authors: Seyed Mohsen Mousavi, Ali Golkarian, Seyed Amir Naghibi, Bahareh Kalantar, Biswajeet PradhanAbstract:This study intends to investigate the performance of boosted regression tree (BRT) and Frequency Ratio (FR) models in groundwater potential mapping. For this purpose, location of the springs was determined in the western parts of the Mashhad Plain using national reports and field surveys. In addition, thirteen groundwater conditioning factors were prepared and mapped for the modelling process. Those factor maps are: slope degree, slope aspect, altitude, plan curvature, profile curvature, slope length, topographic wetness index, distance from faults, distance from rivers, river density, fault density, land use, and lithology. Then, Frequency Ratio and boosted regression tree models were applied and groundwater potential maps (GPMs) were produced. In the last step, validation of the models was carried out implementing receiver operating characteristics (ROC) curve. According to the results, BRT had area under curve of ROC (AUC-ROC) of 87.2%, while it was seen that FR had AUC-ROC of 83.2% that implies acceptable opeRation of the models. According to the results of this study, topographic wetness index was the most important factor, followed by altitude, and distance from rivers. On the other hand, aspect, and plan curvature were seen to be the least important factors. The methodology implemented in this study could be used for other basins with similar conditions to cope with water resources problem.
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rainfall induced landslide susceptibility assessment at the chongren area china using Frequency Ratio certainty factor and index of entropy
Geocarto International, 2016Co-Authors: Haoyuan Hong, Biswajeet Pradhan, Ahmed M Youssef, Wei Chen, Dieu Tien BuiAbstract:AbstractThe main objective of the study was to evaluate and compare the overall performance of three methods, Frequency Ratio (FR), certainty factor (CF) and index of entropy (IOE), for rainfall-induced landslide susceptibility mapping at the Chongren area (China) using geographic information system and remote sensing. First, a landslide inventory map for the study area was constructed from field surveys and interpretations of aerial photographs. Second, 15 landslide-related factors such as elevation, slope, aspect, plan curvature, profile curvature, stream power index, sediment transport index, topographic wetness index, distance to faults, distance to rivers, distance to roads, landuse, NDVI, lithology and rainfall were prepared for the landslide susceptibility modelling. Using these data, three landslide susceptibility models were constructed using FR, CF and IOE. Finally, these models were validated and compared using known landslide locations and the receiver operating characteristics curve. The resu...
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landslide susceptibility mapping at al hasher area jizan saudi arabia using gis based Frequency Ratio and index of entropy models
Geosciences Journal, 2015Co-Authors: Ahmed M Youssef, Mohamed Alkathery, Biswajeet PradhanAbstract:Mountain areas in the southern western corner of the Kingdom of Saudi Arabia frequently suffer from various types of landslides due to rain storms and anthropogenic activities. To resolve the problem related to landslides, landslide susceptibility map is important as a quick and safe mitigation measure and to help making strategic planning by identifying the most vulnerable areas. This paper summarizes findings of landslide susceptibility analysis at Al-Hasher area, Jizan, KSA, using two statistical models: Frequency Ratio and index of entropy models with the aid of GIS tools and remote sensing data. The landslide locations (inventory map) were identified in the study area using historical records, interpretation of high-resolution satellite images that include Geo-Eye in 2.5 m and Quickbird in 0.6m resolution, topographic maps of 1:10,000 scale, and multiple field investigations. A total of 207 landslides (80% out of 257 detected landslides) were randomly selected for model training, and the remaining 50 landslides (19%) were used for the model validation. Ten landslide conditioning factors including slope angle, slope-aspect, altitude, curvature, lithology, distance to lineaments, normalized difference vegetation index (NDVI), distance to roads, precipitation, and distance to streams, were extracted from spatial database. Using these conditioning factors and landslide locations, landslide susceptibility and weights of each factor were analyzed by using Frequency Ratio and index of entropy models. Our findings showed that the existing landslides of high and very high susceptibility classes cover nearly 80.4% and 79.1% of the susceptibility maps produced by Frequency Ratio and index of entropy models respectively. For verification, receiver operating characteristic (ROC) curves were drawn and the areas under the curve (AUC) were calculated for success and prediction rates. For success rate the results revealed that for the index of entropy model (AUC = 77.9%) is slightly lower than Frequency Ratio model (AUC = 78.8%). For the prediction rate, it was found that the index of entropy model (AUC = 74.9%) is slightly lower than the Frequency Ratio model (AUC = 76.7%). The landslide susceptibility maps produced from this study could help decision makers, planners, engineers, and urban areas developers to make suitable decisions.
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an integrated drastic model using Frequency Ratio and two new hybrid methods for groundwater vulnerability assessment
Natural Hazards, 2015Co-Authors: Aminreza Neshat, Biswajeet PradhanAbstract:Groundwater management can be effectively implemented by mapping groundwater contamination. Intense agricultural activities and land overexploitation have resulted in groundwater contamination, which is becoming a critical issue, specifically in areas where fertilizers are extensively used on large plantations. The goal of this study was to develop an integrated DRASTIC model with a Frequency Ratio (FR) as a novel approach. Two new hybrid methods namely single-parameter sensitivity analysis (SPSA) and an analytical hierarchy process (AHP) are also implemented for adjusting feature weights to local settings. The FR is used for DRASTIC model rates, whereas both SPSA and AHP are used for DRASTIC weights. The FR-DRASTIC, FR-SPSA and FR-AHP methods are developed; nitrate samples from the same month in different years are used for analysis and correlation (May 2010 and May 2012). The first nitrate samples are interpolated using the Kriging approach. The Kerman plain is used as an example, which is located in southeastern part of Iran. Additionally, the new methods are employed in the study area to compare with each other and the original DRASTIC model. The validation results exhibited that using FR approach improved the correlation between vulnerability index and nitrate concentRations compared with original DRASTIC vulnerability correlation which was 0.37. The results indicated that the new hybrid methods exhibited higher correlation 0.75 in the FR-DRASTIC model. Correlations of the FR-SPSA and FR-AHP approaches were 0.77 and 0.80. Hence, the new hybrid methods are more effective and provide reasonably good results. Furthermore, quantitative measures of vulnerability offer an excellent opportunity to effectively prevent as well as reduce contamination.
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landslide susceptibility mapping along bhalubang shiwapur area of mid western nepal using Frequency Ratio and conditional probability models
Journal of Mountain Science, 2014Co-Authors: Amar Deep Regmi, Kohki Yoshida, Hamid Reza Pourghasemi, Megh Raj Dhital, Biswajeet PradhanAbstract:Roads constructed in fragile Siwaliks are prone to large number of instabilities. Bhalubang-Shiwapur section of Mahendra Highway lying in Western Nepal is one of them. To understand the landslide causative factor and to predict future occurrence of the landslides, landslide susceptibility mapping (LSM) of this region was carried out using Frequency Ratio (FR) and weights-of-evidence (W of E) models. These models are easy to apply and give good results. For this, landslide inventory map of the area was prepared based on the aerial photo interpretation, from previously published/unpublished reposts, and detailed field survey using GPS. About 332 landslides were identified and mapped, among which 226 (70%) were randomly selected for model training and the remaining 106 (30%) were used for validation purpose. A spatial database was constructed from topographic, geological, and land cover maps. The reclassified maps based on the weight values of Frequency Ratio and weights-of-evidence were applied to get final susceptibility maps. The resultant landslide susceptibility maps were verified and compared with the training data, as well as with the validation data. From the analysis, it is seen that both the models were equally capable of predicting landslide susceptibility of the region (W of E model (success rate = 83.39%, prediction rate = 79.59%); FR model (success rate = 83.31%, prediction rate = 78.58%)). In addition, it was observed that the distance from highway and lithology, followed by distance from drainage, slope curvature, and slope gradient played major role in the formation of landsides. The landslide susceptibility maps thus produced can serve as basic tools for planners and engineers to carry out further development works in this landslide prone area.
Anxue Zhang - One of the best experts on this subject based on the ideXlab platform.
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dual band annular slot antenna loaded by reactive components for dual sense circular polarization with flexible Frequency Ratio
IEEE Access, 2018Co-Authors: Junwei Shi, Tayyab Ali Khan, Juan Chen, Anxue ZhangAbstract:This paper proposes a new design of dual-band reactively loaded annular slot antenna for dual-sense circular polarization radiation. Two concentric annular slots excited by a common microstrip feedline are employed to realize dual-band opeRation. Each slot can radiate a circularly polarized (CP) wave with a specified sense at its one or one-and-a-half wavelength resonance, given that an appropriately valued reactive component, i.e., capacitor or inductor, is introduced at a pre-determined location. A small Frequency Ratio (FR) can be achieved between the two oppositely sensed CP bands when a capacitor and an inductor are loaded, respectively, onto the inner and outer annular slots. Contrarily, two oppositely sensed CP bands that possess a large FR can be yielded when an inductor and a capacitor are loaded onto the inner and outer annular slots, respectively. For experimental verification, two antenna prototypes with FRs of 1.63 and 2.41 have been designed, fabricated, and measured. The measurement results exhibit a good agreement with the simulated ones. Details of design concerns and experimental results are presented and discussed.
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Direct Synthesis Method for Dual-band Bandpass Filters with Wide Fractional Bandwidth Range and Center Frequency Ratio
IEEE Transactions on Circuits and Systems II: Express Briefs, 2024Co-Authors: Xinyue Dai, Qian Yang, Cheng Guo, Anxue ZhangAbstract:This brief proposes a direct synthesis method for dual-band filters based on Frequency transformations. This method can synthesize dual-band bandpass filters (BPFs) with a large range of fractional bandwidth (8.5%-56%) and at the same time, wide center Frequency Ratio (2-4). A novel circuit conversion scheme is proposed to ease the difficulty of implementing complex circuit and reduce the sensitivity of S parameters to the values of the circuit elements significantly (The influence of 20% fluctuation of inductance on S11 is within 5dB). In order to prove the validity of the proposed method, a 3rd-order narrowband dual-band BPF with center frequencies of 1 GHz and 2 GHz (small Frequency Ratio) and a 5th-order wideband dual-band BPF with center frequencies of 0.5 GHz and 2 GHz (large Frequency Ratio) are designed and fabricated, the simulated and measured results have good agreement.
Saro Lee - One of the best experts on this subject based on the ideXlab platform.
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application of probabilistic based Frequency Ratio model in groundwater potential mapping using remote sensing data and gis
Arabian Journal of Geosciences, 2014Co-Authors: Mohamad Abd Manap, Biswajeet Pradhan, Saro Lee, Haleh Nampak, Wan Nor Azmin Sulaiman, Mohammad Firuz RamliAbstract:The main goal of this study is to investigate the application of the probabilistic-based Frequency Ratio (FR) model in groundwater potential mapping at Langat basin in Malaysia using geographical information system. So far, the approach of probabilistic Frequency Ratio model has not yet been used to delineate groundwater potential in Malaysia. Moreover, this study includes the analysis of the spatial relationships between groundwater yield and various hydrological conditioning factors such as elevation, slope, curvature, river, lineament, geology, soil, and land use for this region. Eight groundwater-related factors were collected and extracted from topographic data, geological data, satellite imagery, and published maps. About 68 groundwater data with high potential yield values of ≥11 m3/h were randomly selected using statistical software of SPSS. Then, the groundwater data were randomly split into a training dataset 70 % (48 borehole data) for training the model and the remaining 30 % (20 borehole data) was used for validation purpose. Finally, the Frequency Ratio coefficients of the hydrological factors were used to generate the groundwater potential map. The validation dataset which was not used during the FR modeling process was used to validate the groundwater potential map using the prediction rate method. The validation results showed that the area under the curve for Frequency model is 84.78 %. As far as the performance of the FR approach is concerned, the results appeared to be quite satisfactory, i.e., the zones determined on the map being zones of relative groundwater potential. This information could be used by government agencies as well as private sectors as a guide for groundwater exploRation and assessment in Malaysia.
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Landslide hazard mapping at Selangor, Malaysia using Frequency Ratio and logistic regression models
Landslides, 2007Co-Authors: Saro Lee, Biswajeet PradhanAbstract:The aim of this study is to evaluate the landslide hazards at Selangor area, Malaysia, using Geographic Information System (GIS) and Remote Sensing. Landslide locations of the study area were identified from aerial photograph interpretation and field survey. Topographical maps, geological data, and satellite images were collected, processed, and constructed into a spatial database in a GIS platform. The factors chosen that influence landslide occurrence were: slope, aspect, curvature, distance from drainage, lithology, distance from lineaments, land cover, vegetation index, and precipitation distribution. Landslide hazardous areas were analyzed and mapped using the landslide-occurrence factors by Frequency Ratio and logistic regression models. The results of the analysis were verified using the landslide location data and compared with probability model. The comparison results showed that the Frequency Ratio model (accuracy is 93.04%) is better in prediction than logistic regression (accuracy is 90.34%) model.
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landslide susceptibility mapping in the damrei romel area cambodia using Frequency Ratio and logistic regression models
Environmental Earth Sciences, 2006Co-Authors: Saro Lee, Touch SambathAbstract:This study applied, tested and compared a probability model, a Frequency Ratio and statistical model, a logistic regression to Damre Romel area, Cambodia, using a geographic information system. For landslide susceptibility mapping, landslide locations were identified in the study area from interpretation of aerial photographs and field surveys, and a spatial database was constructed from topographic maps, geology and land cover. The factors that influence landslide occurrence, such as slope, aspect, curvature and distance from drainage were calculated from the topographic database. Lithology and distance from lineament were extracted and calculated from the geology database. Land cover was classified from Landsat TM satellite imagery. The relationship between the factors and the landslides was calculated using Frequency Ratio and logistic regression models. The relationships, Frequency Ratio and logistic regression coefficient were overlaid to make landslide susceptibility map. Then the landslide susceptibility map was compared with known landslide locations and tested. As the result, the Frequency Ratio model (86.97%) and the logistic regression (86.37%) had high and similar prediction accuracy. The landslide susceptibility map can be used to reduce hazards associated with landslides and to land cover planning.
Guodong Zhao - One of the best experts on this subject based on the ideXlab platform.
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a discrete time low Frequency Ratio nearest level modulation strategy for modular multilevel converters with small number of power modules
IEEE Access, 2019Co-Authors: Ke Shen, Shaozhe Wang, Dan Zhao, Guodong ZhaoAbstract:There has been increased usage of modular multilevel converters (MMCs) in the medium-voltage traction drives for increased efficiency and reduced switching losses. One of the disadvantages of utilizing the conventional nearest level modulation (NLM) scheme is the poor performance of output voltage distortion and dynamic response. The control design of low-Frequency Ratio for the MMC system with a small number of power modules should, therefore, be considered due to the industrial opeRation requirements. This paper focuses on the voltage state switching mechanism of a discrete-time low-Frequency-Ratio NLM strategy. A five-segment voltage state allocation guideline based on voltage state smooth transition is analyzed in the discrete-time domain. The proposed strategy features a linearly synthesized output voltage by means of simple arithmetic calculations to determine the switching sequences and the duRation times. The overall strategy benefits from reduced dv/dt in the rising/falling edges of the output voltage and the unnecessary switching actions are highly constrained. The simulation analysis and the experimental results validate the proposed modulation strategy and establish its effectiveness.
E K N Yung - One of the best experts on this subject based on the ideXlab platform.
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dual band circularly polarized cpw fed slot antenna with a small Frequency Ratio and wide bandwidths
IEEE Transactions on Antennas and Propagation, 2011Co-Authors: Canhui Chen, E K N YungAbstract:A novel dual-band circularly-polarized (CP) CPW-fed slot antenna is proposed in this communication. This antenna characterizes a small Frequency Ratio and wide CP bandwidths. The dual-band opeRations are realized by using two parallel monopoles, one curved monopole and one fork-shaped monopole. In addition, a crane-shaped strip is placed in the ground plane to achieve circular polarization. The experimental results show that the antenna has the axial Ratio bandwidths of 9% for the lower band and 11% for the upper band. Both bands are left handed. The Frequency Ratio of the upper band to the lower band is 1.286 (1.98 GHz/1.54 GHz). Other characteristics such as impedance bandwidths, radiation patterns and gains will also be presented.
