scholarly journals Opportunistic Rain Rate Estimation from Measurements of Satellite Downlink Attenuation: A Survey

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5872
Author(s):  
Filippo Giannetti ◽  
Ruggero Reggiannini
Keyword(s):  
Rain Rate ◽  
Regional Scale ◽  
Rainfall Rate ◽  
Estimation Accuracy ◽  
Radio Link ◽  
Infrared Band ◽  
Research Issues ◽  
Main Research ◽  
Rate Estimation ◽  
The Impact

Recent years have witnessed a growing interest in techniques and systems for rainfall surveillance on regional scale, with increasingly stringent requirements in terms of the following: (i) accuracy of rainfall rate measurements, (ii) adequate density of sensors over the territory, (iii) space-time continuity and completeness of data and (iv) capability to elaborate rainfall maps in near real time. The devices deployed to monitor the precipitation fields are traditionally networks of rain gauges distributed throughout the territory, along with weather radars and satellite remote sensors operating in the optical or infrared band, none of which, however, are suitable for full compliance to all of the requirements cited above. More recently, a different approach to rain rate estimation techniques has been proposed and investigated, based on the measurement of the attenuation induced by rain on signals of pre-existing radio networks either in terrestrial links, e.g., the backhaul connections in cellular networks, or in satellite-to-earth links and, among the latter, notably those between geostationary broadcast satellites and domestic subscriber terminals in the Ku and Ka bands. Knowledge of the above rain-induced attenuation permits the retrieval of the corresponding rain intensity provided that a number of meteorological and geometric parameters are known and ultimately permits estimating the rain rate locally at the receiver site. In this survey paper, we specifically focus on such a type of “opportunistic” systems for rain field monitoring, which appear very promising in view of the wide diffusion over the territory of low-cost domestic terminals for the reception of satellite signals, prospectively allowing for a considerable geographical capillarity in the distribution of sensors, at least in more densely populated areas. The purpose of the paper is to present a broad albeit synthetic overview of the numerous issues inherent in the above rain monitoring approach, along with a number of solutions and algorithms proposed in the literature in recent years, and ultimately to provide an exhaustive account of the current state of the art. Initially, the main relevant aspects of the satellite link are reviewed, including those related to satellite dynamics, frequency bands, signal formats, propagation channel and radio link geometry, all of which have a role in rainfall rate estimation algorithms. We discuss the impact of all these factors on rain estimation accuracy while also highlighting the substantial differences inherent in this approach in comparison with traditional rain monitoring techniques. We also review the basic formulas relating rain rate intensity to a variation of the received signal level or of the signal-to-noise ratio. Furthermore, we present a comprehensive literature survey of the main research issues for the aforementioned scenario and provide a brief outline of the algorithms proposed for their solution, highlighting their points of strength and weakness. The paper includes an extensive list of bibliographic references from which the material presented herein was taken.

scholarly journals Evaluation of Propagation Losses Due to Rain Attenuated Signal on Terrestrial Radio Links over Jos, Plateau State Nigeria

2019 ◽  
pp. 1-8
Author(s):  
O. J. Igbekele ◽  
J. T. Zhimwang ◽  
E. P. Ogherohwo
Keyword(s):  
Rain Rate ◽  
Rainfall Rate ◽  
Radio Link ◽  
Rate Data ◽  
Weather Station ◽  
Microsoft Excel ◽  
Application Package ◽  
Jos Plateau ◽  
Propagation Losses ◽  
Plateau State

This paper presents the evaluation of propagation losses due to rain attenuated signal on   terrestrial radio link. Rain rate data were measured using Davis weather station for the months of July, August and October 2017 at (9.9565° N, 8.8583° E; 1258 meters) Jos Plateau state of Nigeria. The data were analyzed using Microsoft Excel application package. Results were calculated based ITU-Recommendation. The result for the month of July shows that rain   attenuated signals become more severe from rain rate of 90 mm/hr at 0.014% to 160 mm/hr at 0.002% with attenuation of 31.215dB and 105.951dB respectively. Also, the month of August shows that rain attenuated signals become more severe from rain rate of 70mm/hr at 0.017% to 200mm/hr at 0.002% with attenuation of 69.509dB and 108.324dB respectively. Furthermore, the month of October shows that rain attenuated signals become more severe from rain rate of 70mm/hr at 0.014% to 160 mm/hr at 0.004 with attenuation of 50.301dB and 135.336dB respectively. Therefore, results from this study revealed that rain attenuated signals on terrestrial radio links in Jos-Nigeria is more severe at higher rainfall rate (above 60 mm/hr) and lower exceeded frequency percentage of time (0.01% to 0.001%).

scholarly journals Actual challenges of labor market and their gender implications for employment

POPULATION ◽  
2020 ◽  
Vol 23 (2) ◽  
pp. 136-148
Author(s):  
Zoya A. Khotkina
Keyword(s):  
Labor Market ◽  
Service Sector ◽  
Gender Segregation ◽  
Women's Employment ◽  
Women’S Employment ◽  
Research Issues ◽  
Main Research ◽  
The Government ◽  
Employment Of Women ◽  
The Impact

The main research issues discussed in the article concern the impact of technological and epidemiological challenges on the employment of women and men, as well as the reasons for their asymmetric impact on employees depending on gender. The choice of these two challenges is determined, on the one hand, by their relevance, and on the other, by the fact that, although they are fundamentally different in both character and duration of their impact on the labor market, the consequences of their impact on women’s employment are the same and in both cases lead to job losses. The article shows that the same consequences for women’s employment from such different challenges are not accidental. This is due to the fact that the causes and risk factors of priority job loss for women as a result of the technological and epidemiological challenges are identical, since they are based on gender segregation of employment in the labor market, which divides jobs and entire industries into «male» and «female». In the technological challenge, the reason for the priority and more widespread loss of jobs by women is due to the fact that they are more often than men engaged in routine work in which is a large proportion of repetitive operations that are easy to automate and delegate to robots or artificial intelligence (AI). During the epidemiological challenge, more “female” than “male” jobs fell into the risk zone of unemployment, because as a result of self-isolation most enterprises and organizations in the service sphere, such as shopping centers, hairdressers and beauty salons, hotels and boarding houses, museums and libraries were closed, as well as airports and travel agencies — and all these enterprises employed mainly women. On account of the high risk of unemployment, these activities were included in the “List of economy sectors most affected by coronavirus” developed by the Government to provide priority targeted support. However, according to the information from the Ministry of Finance, less than a fifth of the service sector organizations and individual entrepreneurs will be able to receive this assistance, and therefore it is unlikely to avoid an increase in female unemployment.

scholarly journals An Algorithm for Real-Time Rainfall Rate Estimation by Using Polarimetric Radar: RIME

2009 ◽  
Vol 10 (1) ◽  
pp. 227-240 ◽  
Author(s):  
Francesco Silvestro ◽  
Nicola Rebora ◽  
Luca Ferraris
Keyword(s):  
Decision Tree ◽  
Real Time ◽  
Rain Rate ◽  
Rain Gauge ◽  
Rainfall Rate ◽  
Retrieval Algorithm ◽  
Polarimetric Radar ◽  
Regional Network ◽  
Rate Estimation ◽  
Significant Events

Abstract Polarimetric radars provide measurements that describe the shape and dimensions of hydrometeors and are unaffected by calibration, attenuation, and the presence of ice. These measurements can potentially lead to a more detailed description of hydrometeors and to an improvement in quantitative rainfall rate estimation. The authors present an algorithm that exploits polarimetric measures for rain-rate estimation and investigate its application in a real-time framework by using measurements from the C-band polarimetric radar at Monte Settepani in Savona, Italy. It is based on a flowchart decision tree that allows the use of the best rain-rate retrieval algorithm, depending on the value of polarimetric variables. The methodology was applied to a real-time framework for more than a year, and the results were presented for all the significant events observed during the test period. To evaluate the performance of the algorithm, a comparison was made with rain gauge observation from a dense regional network. The performances of the algorithm were compared with those obtained by standard operational Z–R formulations to evaluate the benefit of this approach for operational applications.

THE IMPACT OF SERVICE QUALITY ON BRAND LOYALTY OF DTAC SELULER SERVICE USERS

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Debby Arisandi
Keyword(s):  
Service Quality ◽  
Customer Service ◽  
Service Provider ◽  
Brand Loyalty ◽  
Service Industry ◽  
Positive Impact ◽  
Relevant Literature ◽  
Field Research ◽  
Main Research ◽  
The Impact

<p>Purpose- In the GSM seluler telephony sector, the main condition for protecting the subscriber base is to win customer to be loyalty, a key necessity for the maintenance of a brand loyalty in the long term. To achieve this aim, service quality must be measured and identified. This paper’s aim is to measure the effects of service quality towards brand loyalty on DTAC seluler service provider. This study will explore the relationship between service quality and brand loyalty in the seluler service industry.</p><p>Design/methodology/approach- The main research target sample covered 200 seluler phone users in Prince of Songka University, Hatyai campus. Field research was conducted. The questionnaire was formed by a synthesis of existing constructs in relevant literature. Reliability tests, descriptive statistic, and regressions analyses were performed to both confirm scale reliability and answer the research questions. The data were analysed by moderated regression analysis to test the hypotheses.</p><p>Findings- The findings of this study show that an overall service quality directly affects brand loyalty. Network quality, customer service, pricing structure and billing system are the service quality dimensions that have significant positive influence on brand loyalty, which in turn has a significant positive impact on brand loyalty 43,5%. Therefore, it plays a crucial role in winning customer loyalty.</p><p>Originality/value- It is of great importance for seluler operators in a mature market such as that of Thailand, to understand what the drivers of brand loyalty are. The present study produced useful findings, which can be utilized by seluler service provider managers, in their effort to develop and implement successful brand loyalty strategies. With respect to the findings, pricing structure has the most importance than others dimensions of service quality which provides positive outcomes on brand loyalty, not only in the present but also in the future. So, the effect of pricing structure on brand loyalty becomes greater than the effect of others dimenstions of service quality. Therefore, any GSM operator who wishes to preserve its existing subscriber base should concentrate on winning its subscribers’ loyalty, especially for DTAC.</p>Keywords- Seluler Services, Brand Loyalty, Service Quality

scholarly journals Multilayer Soil Moisture Mapping at a Regional Scale from Multisource Data via a Machine Learning Method

2019 ◽  
Vol 11 (3) ◽  
pp. 284 ◽  
Author(s):  
Linglin Zeng ◽  
Shun Hu ◽  
Daxiang Xiang ◽  
Xiang Zhang ◽  
Deren Li ◽  
...  
Keyword(s):  
Machine Learning ◽  
Soil Moisture ◽  
Regional Scale ◽  
Remotely Sensed ◽  
Temporal Variations ◽  
Training Data ◽  
Estimation Accuracy ◽  
Learning Approaches ◽  
Remotely Sensed Data ◽  
Deep Soil

Soil moisture mapping at a regional scale is commonplace since these data are required in many applications, such as hydrological and agricultural analyses. The use of remotely sensed data for the estimation of deep soil moisture at a regional scale has received far less emphasis. The objective of this study was to map the 500-m, 8-day average and daily soil moisture at different soil depths in Oklahoma from remotely sensed and ground-measured data using the random forest (RF) method, which is one of the machine-learning approaches. In order to investigate the estimation accuracy of the RF method at both a spatial and a temporal scale, two independent soil moisture estimation experiments were conducted using data from 2010 to 2014: a year-to-year experiment (with a root mean square error (RMSE) ranging from 0.038 to 0.050 m3/m3) and a station-to-station experiment (with an RMSE ranging from 0.044 to 0.057 m3/m3). Then, the data requirements, importance factors, and spatial and temporal variations in estimation accuracy were discussed based on the results using the training data selected by iterated random sampling. The highly accurate estimations of both the surface and the deep soil moisture for the study area reveal the potential of RF methods when mapping soil moisture at a regional scale, especially when considering the high heterogeneity of land-cover types and topography in the study area.

scholarly journals Measuring Hydrometeors Using a Precipitation Microphysical Characteristics Sensor: Sampling Effect of Different Bin Sizes on Drop Size Distribution Parameters

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xichuan Liu ◽  
Taichang Gao ◽  
Yuntao Hu ◽  
Xiaojian Shu
Keyword(s):  
Drop Size ◽  
Rain Rate ◽  
Monte Carlo Model ◽  
Rain Gauge ◽  
Sampling Schemes ◽  
Distribution Parameters ◽  
Optimum Sampling ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

In order to improve the measurement of precipitation microphysical characteristics sensor (PMCS), the sampling process of raindrops by PMCS based on a particle-by-particle Monte-Carlo model was simulated to discuss the effect of different bin sizes on DSD measurement, and the optimum sampling bin sizes for PMCS were proposed based on the simulation results. The simulation results of five sampling schemes of bin sizes in four rain-rate categories show that the raw capture DSD has a significant fluctuation variation influenced by the capture probability, whereas the appropriate sampling bin size and width can reduce the impact of variation of raindrop number on DSD shape. A field measurement of a PMCS, an OTT PARSIVEL disdrometer, and a tipping bucket rain Gauge shows that the rain-rate and rainfall accumulations have good consistencies between PMCS, OTT, and Gauge; the DSD obtained by PMCS and OTT has a good agreement; the probability of N0, μ, and Λ shows that there is a good agreement between the Gamma parameters of PMCS and OTT; the fitted μ-Λ and Z-R relationship measured by PMCS is close to that measured by OTT, which validates the performance of PMCS on rain-rate, rainfall accumulation, and DSD related parameters.

Exploring the impact of introducing a physical model into statistical methods on the evaluation of regional scale debris flow susceptibility

2021 ◽  
Vol 106 (1) ◽  
pp. 881-912
Author(s):  
Jingbo Sun ◽  
Shengwu Qin ◽  
Shuangshuang Qiao ◽  
Yang Chen ◽  
Gang Su ◽  
...  
Keyword(s):  
Debris Flow ◽  
Physical Model ◽  
Statistical Methods ◽  
Regional Scale ◽  
The Impact ◽  
Debris Flow Susceptibility

scholarly journals Dynamic Optimization Method for Broadband ADCP Waveform with Environment Constraints

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3768
Author(s):  
Yongshou Yang ◽  
Shiliang Fang
Keyword(s):  
Distance Estimation ◽  
Acoustic Doppler Current Profiler ◽  
Optimization Method ◽  
Measurement Range ◽  
Velocity Estimation ◽  
Estimation Accuracy ◽  
Dynamic Configuration ◽  
Optimal Velocity ◽  
Flood Warning ◽  
The Impact

Broadband acoustic Doppler current profiler (ADCP) is widely used in agricultural water resource explorations, such as river discharge monitoring and flood warning. Improving the velocity estimation accuracy of broadband ADCP by adjusting the waveform parameters of a phase-encoded signal will reduce the velocity measurement range and water stratification accuracy, while the promotion of stratification accuracy will degrade the velocity estimation accuracy. In order to minimize the impact of these two problems on the measurement results, the ADCP waveform optimization problem that satisfies the environment constraints while keeping high velocity estimation accuracy or stratification accuracy is studied. Firstly, the relationship between velocity or distance estimation accuracy and signal waveform parameters is studied by using an ambiguity function. Secondly, the constraints of current velocity range, velocity distribution and other environmental characteristics on the waveform parameters are studied. For two common measurement applications, two dynamic configuration methods of waveform parameters with environmental adaptability and optimal velocity estimation accuracy or stratification accuracy are proposed based on the nonlinear programming principle. Experimental results show that compared with the existing methods, the velocity estimation accuracy of the proposed method is improved by more than 50%, and the stratification accuracy is improved by more than 22%.

scholarly journals Modified Nanoclays/Straw Fillers as Functional Additives of Natural Rubber Biocomposites

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 799
Author(s):  
Justyna Miedzianowska ◽  
Marcin Masłowski ◽  
Przemysław Rybiński ◽  
Krzysztof Strzelec
Keyword(s):  
Natural Rubber ◽  
Raw Materials ◽  
Research Work ◽  
Damping Properties ◽  
Main Research ◽  
Functional Additives ◽  
Different Types ◽  
Elastomeric Materials ◽  
Research Goal ◽  
The Impact

Increasingly, raw materials of natural origin are used as fillers in polymer composites. Such biocomposites have satisfactory properties. To ensure above-average functional properties, modifications of biofillers with other materials are also used. The presented research work aimed to produce and characterize elastomeric materials with a straw-based filler and four different types of montmorillonite. The main research goal was to obtain improved functional parameters of vulcanizates based on natural rubber. A series of composites filled with straw and certain types of modified and unmodified nano-clays in various ratios and amounts were prepared. Then, they were subjected to a series of tests to assess the impact of the hybrids used on the final product. It has been shown that the addition of optimal amounts of biofillers can, inter alia, increase the tensile strength of the composite, improve damping properties, extend the burning time of the material and affect the course of vulcanization or cross-linking density.

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