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Satellite to  earth microwave link 
		performance due to rain fade in India

Satellite to earth microwave link performance due to rain fade in India

For a reliable communication system, unavailability time during a year has to be kept at 0.01 percent. This corresponds to availability time of 99.99 percent during a year. Rainfall with one-minute integration time is very important parameter for predicting attenuation at 0.01% of time. For 99.5% of availability at a BER of 5E-7 or better the link availability threshold margins have to be determined [15]. The non-homogeneous rain structure can lead to different specific attenuation in real time. Rain drops can assume various shapes, i.e. spherical for small size cells, oblate spheroid for medium and oblate distorted for large size rain drops. This information is needed to indicate the best distribution model of rain falls within tropical climate in the rain attenuation model simulation [8].The measured rain rate data is converted from measured long term annual rainfall data from the deviation curves. With the increase of system reliability, deviation between predicted attenuation of measured maximum and minimum R 0.01 and ITU-R predicted
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Investigation of the Performance of Site Diversity through Rain Gauge Measurements in South-South Nigeria

Investigation of the Performance of Site Diversity through Rain Gauge Measurements in South-South Nigeria

Site diversity is an effective technique to mitigate rain attenuation, especially in regions where rainfall rates are high. The South-South region of Nigeria is characterized by the tropical rain forest climate, exhibiting high rainfall rates almost all year round. This paper investigates the performance of site diversity technique in the South-South Nigeria at Ka-band frequency of 20 GHz. Rainfall data obtained from the Nigerian Meteorological Agency (NIMET) over a period of five years (2010 to 2014) were analysed to derive the one-minute rainfall rate distribution for four selected earth stations (University of Uyo, Uyo; Akwa Ibom International Airport, Uyo; Margaret Ekpo International Airport, Calabar; and Port Harcourt International Airport, Port Harcourt) within the South-South Nigeria. The link parameters of NigComSat-1R were used with the ITU-R model for rain attenuation to estimate the rain attenuation distribution through an annual cumulative distribution and percentage of outage time between 0.01 to 100 %. Site diversity (SD) was implemented, taking University of Uyo as the reference site. The results obtained shows that the SD gain between the University of Uyo and Port Harcourt International Airport is higher than the SD gain recorded between University of Uyo and Margaret Ekpo International Airport. This is consistent with the fact that longer distances between the earth stations yield higher SD gain.
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Comparative Studies of the Rain Attenuation Predictions for Tropical Regions

Comparative Studies of the Rain Attenuation Predictions for Tropical Regions

it can be seen that the ITU-R model is definitely unsuitable at higher frequencies. Now the argument is that, we want to determine which one, out of these four models, is most suitable for predicting rain attenuation in Malaysian tropical climate. To do this, the Recommendation ITU-R P.311-13 [19] has been used for determining the prediction errors exceeding time percentages in the range 0.001% to 0.1%. Therefore percentage errors between measured terrestrial data A m (dB) and the model’s predictions A P (dB) are calculated for each

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Monthly variation in Rainfall Attenuation for Ka band Satellite Communication for monsoon in Ahmedabad and New Delhi Alpesh H. Dafda 1Dr. Kishor G. Maradia2

Monthly variation in Rainfall Attenuation for Ka band Satellite Communication for monsoon in Ahmedabad and New Delhi Alpesh H. Dafda 1Dr. Kishor G. Maradia2

Rainfall intensity for 64 years monsoon months is calculated for Ahmedabad and New Delhi. According to different rain climate zones for Asia-Pacific Region suggested by ITU-R [12], New Delhi and Ahmedabad come under region K. For this K region, rain intensity exceeding 0.01% of an average year is 42 mm/hour. The rainfall intensity values obtained in this work is also near 42 mm/hour which proves the authentication of the method invented for estimation. In fact the values obtained are an improvement over ITU-R model, as the estimation is done for 64 years. The other outcome of this work is that it proves that for accurate rainfall attenuation predictions, point rainfall data or fine data is not needed and even the coarse data can be used for accurate rainfall predictions. The work shows that the rainfall intensity and hence the rainfall attenuation is most intense during the month of July for both
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Rain, Rain, Go Away? The Investment Climate, State Business Relations and Firm Performance in India

Rain, Rain, Go Away? The Investment Climate, State Business Relations and Firm Performance in India

In this paper, we dig deeper into the determinants of better investment climate outcomes by focusing on their underlying causes, which we argue are effective state business relations. In our view, a synergistic relationship between the state and the business sector, which is based on strong and well organised states and private sector associations, is more likely to lead to the provision of public goods such as roads and electricity, and a lower regulatory burden on the private sector. In the next section, we argue why this is the case, and why effective state business relations may improve firm performance, and hence, overall economic welfare.
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Bayesian Bias Correction of Satellite Rainfall Estimates for Climate Studies

Bayesian Bias Correction of Satellite Rainfall Estimates for Climate Studies

Keywords: Bayesian bias correction; satellite rainfall; rain gauge; climate studies; East Africa 33.. 34.[r]

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Perceptions of Climate Change, Weather Shocks, and Impacts on Households in the MENA region

Perceptions of Climate Change, Weather Shocks, and Impacts on Households in the MENA region

The goal of this chapter was to contribute to a better understanding of perceptions of climate change and environmental degradation, as well as extreme weather events and their impact on households in the MENA region. The analysis was based on household surveys implemented in five countries, with a focus in each country on two areas more susceptible to be affected by adverse weather shocks. The data suggest that a substantial majority of households do perceive important changes in the climate and their environment. Some of the most commonly reported changes include more erratic rain, higher temperatures, less rain, dryer and less fertile land, and more frequent droughts. In some areas by contrast, excess rain is the issue, especially when it leads to floods. As expected, these household perceptions of changes in weather patterns and the environment are strongly correlated with the likelihood that households declare having suffered from various types of losses in livelihood due to adverse climatic events. Also as expected, the data suggest that households involved in agriculture, and especially the poor as measured through indices of wealth, are most likely to suffer from losses in crops and income, the two most frequently cited types of losses associated with adverse weather events. By contrast, households who tend to be more protected through a better education and salaried employment are much less likely to suffer from the negative effects of perceived climate change and adverse weather shocks. While none of those results are in themselves surprising, they help to set the stage for subsequent chapters devoted to an analysis of how households cope with these changes, first through migration, and then through other coping and adaptation mechanisms.
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Integrating psychosocial safety climate in the JD-R model: A study amongst Malaysian workers

Integrating psychosocial safety climate in the JD-R model: A study amongst Malaysian workers

This study is a part of our project on psychosocial risk factors in Malaysia; the study furthermore trials a psychosocial surveillance tool within one state of Malaysia, namely Selangor. The sampling technique like most surveillance systems (71%) is random sampling from the working population (Dollard, Skinner, Tuckey, & Bailey, 2007). Ideally, climate studies focus on shared perceptions of climate and aggregate individual data to the organisational or unit level. However, according to data presented in a recent meta- analysis by Clarke (2006), only 17% of safety climate studies actually appear to do this. Population sampling poses a challenge when assessing climate phenomena as aggregation at the organisational level is not possible. Nevertheless, it is important to note that our study theorises and considers PSC as a property of the organisation. Despite this drawback, the population sample enables us to test the theories across many organisations, occupations and sectors to determine their general veracity.
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An improved ITU R rain attenuation prediction model over terrestrial microwave links in tropical region

An improved ITU R rain attenuation prediction model over terrestrial microwave links in tropical region

microwave links of DiGi Telecommunications Sdn. Bhd., Malaysia. Each of the microwave systems consists of a microwave MINILINK operating at 15 GHz with data acquisition and processing system. Both transmit and receive antennas are horizontally polarized; and the ele- vation angle is approximately zero degrees. In order to achieve reliable results, the antennas were covered with radome to ensure that the measured rain attenuation was not contaminated by wet antenna losses during measurement. Moreover, scintillations and other atmo- spheric absorptions along the propagation path have not been considered in the study. This is because the vapor absorption is significant at 22 GHz (0.16 dB/km) and the oxygen absorption at 60 GHz (15 dB/km) [5]. The MINILINKs have availability of 99.95% and their specifi- cations are given in Table 1. The positioning of the antennas (transmitter and receivers) ensures that the radiation pattern is such that the sidelobes are not pointing to the ground. So, the level of ground contami- nation (noise) entering the sidelobes is negligible. This implies that there would be negligible interference from any other radiating sources. The dynamic range of the maximum signal strength is about 50 dB for excess (i.e., rain) attenuation. This is adequately suitable for cover- ing the entire dynamic range of rain attenuation for this investigation, since the highest total path attenuation measured is 49.32 dB at 0.001% of the time.
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Theoretical framework for applied climate education: 1.  Adult Learning Concepts and Principles to consider when developing and delivering training

Theoretical framework for applied climate education: 1. Adult Learning Concepts and Principles to consider when developing and delivering training

understanding of this variable climate in terms of how it impacts on production, natural resources and markets is critical for producers and agribusiness to maintain or improve their industry (Hammer et al. 2000). Improving knowledge and skills to better cope with climate is a goal that the Australian government has been working on since drought was no longer to be considered as an ‘exceptional circumstance’ but with an emphasis needing to be on increased self reliance (Anon. 1990).

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Rainfall Variability over Ghana: Model versus Rain Gauge Observation

Rainfall Variability over Ghana: Model versus Rain Gauge Observation

RegCM3 is a 3-dimensional, sigma-coordinate, hydrostatic, compressible, primitive equation regional climate model. It was originally developed in the late 1980s, and it was the first limited area model applied to climate studies [12]. Over the last 25 years, the system has been improved through successive model versions (RegCM1 to RegCM4), incorporating increasingly comprehensive physics packages and interactively coupled components of the climate system (chemistry/aerosol, ocean, lake and biosphere) [13]. RegCM3 is a flexible and versatile system which can be used for different regions of the world especially over West Africa [14] [15] and for a wide range of applications. Data from RegCM3 was analyzed for all the selected stations for the period of 1990 to 2008 and the monthly mean and total rainfall plotted over the period.
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An Investigation on the Use of ITU-R P.1411-7 in 802.11N Path Loss Modelling

An Investigation on the Use of ITU-R P.1411-7 in 802.11N Path Loss Modelling

Figure 2 shows that the average collected received signal strength [14] for all the test locations at all distances was significantly lower than that estimated using Free Space Receive Power Model. The margin between the estimated free space loss and actual 802.11n signal strength is approximately 30 dB. The margin between free space estimation and actual 802.11g signal strength is approximately 40 dB. This is because the collected received power experiences attenuation and loss through scattering, reflection and absorption due to clutter and foliage.

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Performance Analysis Of Rain Attenuation Of An Earth Space Path

Performance Analysis Of Rain Attenuation Of An Earth Space Path

In satellite communication rain causes the most crucial effect in communication degradations and outage in any systems operating at frequencies above 7 GHz applications particularly in the tropical and equatorial climatic regions. Water freezes at 0 0 C mostly in the form of vapour in the air, and when the air temperature falls below 0 0 C the hydrometeors are formed as ice that melts and falls as rain [1]. Because of the moisture content this rain affects the Satellite communication links, both Up and Down. Thermal emission increases the background noise level and scattering and absorption by hydrometeors. Scattering and absorption causes rainfall attenuation in different spectral regions. When the rain drop diameter approaches the size of the operating wavelength rain attenuates the upper spectrum of frequencies. The severity of rain impairment changes with frequency and with different regional locations [11]. Rainfall occurring over satellite link significantly affects transmission signal strength and system performance. Rain attenuation can be statistically estimated at different frequencies, from locations and path geometries, meteorological data and with proper modelling models. Rain causes undesired absorption and results in the variation of the signal strength [5]. Prediction of rain attenuation is grouped into two categories such as physical method (requires input parameters) and empirical method (database for different climatic zones of research). For any reliable communication system, unavailability during a year has to be kept at 0.01 percent, this results the availability of 99.99 percent during a year. So, rainfall with one-minute integration time is very important parameter to predict attenuation 0.01% of time availability [15].
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Climate change as a confounding factor in reversibility of acidification: RAIN and CLIMEX projects

Climate change as a confounding factor in reversibility of acidification: RAIN and CLIMEX projects

Financial support for the RAIN project came from the Norwegian Ministry of Environment, the Research Council of Norway (and its predecessors), Environment Canada, the Ontario Ministry of Environment, the Swedish Environmental Protection Board, the Central Electricity Generating Board (UK), National Power (UK), the Surface Water Acidification Programme (SWAP) and internal research funds from NIVA and NILU. Financial support for CLIMEX came from the Commission of European Communities (EV5V-CT91-0047 and EV5V-CT95-0185), the Dutch Global Change Programme, the Research Council of Norway, the Norwegian Ministry of Environment, the Natural Environment Research Council (UK), Hydrogas Norge A/S and the Norwegian Institute for Water Research. The synthesis and analysis of results reported here was carried out as part of the RECOVER:2010 project (the Commission of European Communities EVK1-CT-1999- 00018). We thank Ann Kristin Buan, Rolf Høgberget, Jarle Håvardstun, Mette Lie and Tore Sørvåg for assistance.
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Possible impacts of climate change on freezing rain in south-central Canada using downscaled future climate scenarios

Possible impacts of climate change on freezing rain in south-central Canada using downscaled future climate scenarios

When regression analysis is used to develop downscaling transfer functions, the transfer functions need to be validated, using an independent dataset, to ensure the models are not over-fitted. To achieve this, a cross-validation scheme was employed to validate all transfer functions for each of the elements. The regression procedure was repeatedly run to develop a transfer function that would validate one-year of independent data for each year in the data set. The vali- dated data were then compared with observations to calcu- late the coefficients of determination (R 2 s), which are shown in Fig. 3. As can be seen from Fig. 3, model R 2 s from model development and cross-validation are similar. For total cloud cover, it is difficult and unnecessary to calculate concordance for the validation results. Hourly cloud cover validations for all stations were compared with observations to calculate the hourly absolute difference (HAD) between the two. The re- sults show that about 61% of the total hours have HAD val- ues ≤1; while 20% have the values ≥5. When hourly cloud cover validations are compared with model calibrations, the proportion with HAD values ≤ 1 is about 96%. Therefore, the downscaling transfer functions for all weather variables used in the study are reliable and over-fitting is not an issue. The performance of hourly downscaling transfer functions varies for different times of day. For all weather variables except dew point temperature and cloud cover, hourly down- scaling transfer functions during the day usually perform bet-
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The Annotation Process of the ITU Web Treebank

The Annotation Process of the ITU Web Treebank

The ITU Web Treebank is a data set contain- ing sentences collected from various domains on the Internet, inspired by recent efforts on other lan- guages (Seddah et al., 2012; Bies et al., 2012). In the absence of Turkish language resources originat- ing from the web, the ITU Web Treebank aimed to establish the first manually annotated web language resource for Turkish. Sulubacak and Eryi˘git (2014) described the annotation procedure of the ITU Web Treebank in detail, outlining the treebank composi- tion, the annotation setting and the syntactic frame- work. Another aim of the ITU Web Treebank was to put forward and demonstrate an approach for anno- tating the non-canonical language found in the web. This paper goes into detail and thoroughly describes
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FORECASTING AND VALIDATING REAL TIME RAINFALL OBSERVATIONS WITH TRADITIONAL VEDIC TECHNIQUES AT GOVARDHAN ECO VILLAGE

FORECASTING AND VALIDATING REAL TIME RAINFALL OBSERVATIONS WITH TRADITIONAL VEDIC TECHNIQUES AT GOVARDHAN ECO VILLAGE

On an average, the vedic predictions at GEV have shown 75% accuracy.The localised simple traditional vedic method is being taught to farmers and it is cost effective. There are no effective models based for predicting rains It seems that technology do not have the necessary information to understand rain patterns. The null hypothesis has been rejected and alternate hypothesis of Rainfall predictions made on Akshaya Tritiya are on an average go hand in hand and in some cases at par with the actual data made at GEV agricultural department through vedic techniques and procedures, was accepted.
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Advisory services, cereal production and consumption in Iraq and in Poland – their influence on achieving food security

Advisory services, cereal production and consumption in Iraq and in Poland – their influence on achieving food security

The climate of Poland is moderate, characterised by the convergence of temperatures between different regions throughout the year and between day and night. The annual average temperature ranges from 5°C to 7°C. Annual precipitation also fluctuates within the country but is mostly between 500-750 mm per year. The driest zone lies in a wide band across central Poland, where precipitation averages just 450-550 mm. The precipitation most suitable for agriculture falls along the southern border with annual amounts of 600- 1300 mm (in the mountains). Rainfall is minimal during the early growing season (April to June) and typically wet during much of the harvests in July and August (Michalczyk and Sposób 2011, World Bank 2016).
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Raindrop Size Distribution Modeling for Radio Link Design Along the Eastern Coast of South Africa

Raindrop Size Distribution Modeling for Radio Link Design Along the Eastern Coast of South Africa

Abstract—A study of the raindrop size distribution along the eastern coast of South Africa (Durban) is presented. The Biweight kernel estimator based on distometer measurement is used to determine the best estimate of the measured raindrop size probability distribution function (pdf). The best kernel estimator, which results in the lowest integral square error (ISE), is used to measure the closeness of the estimated lognormal and gamma pdf of raindrop size to the measured raindrop size distribution. It is established that the optimised lognormal pdf slightly outperforms the optimised gamma pdf in terms of the mean ISE and the RMSE values, with mean ISE values of 0.026 for lognormal and 0.04 for gamma distributions, respectively, and corresponding mean RMSE values of 0.073 and 0.081, respectively. The method-of-moments gamma and lognormal distributions are observed to be worse estimators of the measured pdf than the two optimized distributions. The N (D) distributions using the optimised lognormal and gamma distributions for the region are compared with those for different tropical regions, namely, India, Singapore, Nigeria, Indonesia, and Brazil. While the Indian lognormal N (D) model gives the highest peak for low raindrop sizes for all rain rates, Durban’s gamma and lognormal models exhibit the widest raindrop size spread over all rain rates ranging from 1–120 mm/h. Finally, the specific attenuation due to rain using the Durban models are compared against the ITU-R models and actual measurements over a 19.5 GHz LOS link; the results indicate a need for further work involving both distrometer and radio link measurements for rain rates exceeding 30 mm/h in the eastern coast of South Africa.
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THE RAMIFICATIONS OF CLIMATE VARIABILITY IN AGRICULTURAL FOOD CROPS PRODUCTION AMONG THE SMALLHOLDER FARMERS IN SOUTHERN HIGHLANDS, TANZANIA

THE RAMIFICATIONS OF CLIMATE VARIABILITY IN AGRICULTURAL FOOD CROPS PRODUCTION AMONG THE SMALLHOLDER FARMERS IN SOUTHERN HIGHLANDS, TANZANIA

Implication of climate variability and changing environment potentially subvert agricultural crop production of subsistence and smallholder farmers in the developing countries. Ensuring food security during increasing environmental changes and climate variability constitutes one of the greatest adaptation challenges. Understanding the complex nature of food security and emphasis on increasing food crop production and distribution provide substantial adaptation option and an opportunity for spearheading, generating of information, developing of innovative and improving technologies to adapt to anticipated situations. This paper employed survey to collect information. The study results ascribe that the heavy reliance on rain-fed agriculture, shortage of land and the use of poor technology renders many smallholder farmers vulnerable to the effects of climate variability resulting in the decline of agricultural production, hence food insecurity. The trend is likely to worsen if no measures are put in place to redress the situation. In addressing such challenges, substantial efforts are needed to improve farming practices and the development of adaptation measures that include diversification, climate smart farming practices and improvement of extension and veterinary services. For effectiveness of adoption this will need to include promotion of appropriate and inclusive, environmentally-sound technologies and an enabling policy environment that reinforces actions at the all levels.
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