76 research outputs found
OFDM codée pour le haut débit en fibre optique avec les codes correcteurs convolutifs, BCH, RS et LDPC
Ce document présente une comparaison des performances des modulations OFDM (Orthogonal Frequency Division Multiplexing) codées pour la transmission optique haut débit à l’aide des techniques de codage canal convolutif, BCH, LDPC et Reed Solomon. L’évaluation des performances se base d’une part sur l’EVM (Error Vector Magnitude) afin d’apprécier les effets des imperfections du canal optique; et d’autre part sur l’estimation du taux d’erreur binaire (BER) en fonction de l’OSNR. Les simulations sont réalisées au débit de 10Gbit/s sur 1000 Km dans un environnement de cosimulation avec les logiciels VPITransmissionMaker et Matlab. Les résultats ont révélé que ces codes correcteurs d’erreurs et en particulier les codes LDPC sont bien efficaces et adaptées au haut débit, ils constituent des solutions satisfaisantes pour le COFDM dans la réduction des effets de la dispersion chromatique, de la PMD, des interférences entre symboles (ISI) et des non linéarités.Mots-clés : OFDM, haut débit, BER, fibre optique, codes correcteurs d’erreur.Coded OFDM for high-speed transmission in optical fiber with convolutional, BCH, RS and LDPC codes This paper presents a comparison of the performances of coded OFDM (Orthogonal Frequency Division Multiplexing) for optical broadband transmission using convolutional, BCH, Reed Solomon and LDPC channel coding techniques. The performance evaluation is based firstly on the EVM (Error Vector Magnitude) to assess the effects of imperfections in the channel, and secondly on the estimated bit error rate (BER) based on OSNR. The simulations are performed at a rate of 10Gb/s over 1000 km in a cosimulation environment using VPITransmissionMaker and Matlab software. The results showed that the error correcting codes and particularly LDPC codes are well suited and efficient for broadband, they provide satisfactory solutions for COFDM in reducing the effects of chromatic dispersion, PMD, Inter-symbol interference (ISI) and nonlinearities.Keywords : OFDM, broadband, BER, optical fiber, error correcting codes
Fishers’ Perceptions and Attitudes toward Weather and Climate Information Services for Climate Change Adaptation in Senegal
Climate variability has become a major issue for vital sectors in the context of climate
change. In fisheries, in particular, the effects of climate change are reflected in the decline of fishing
yield and loss of lives during extreme weather events in the sea. This study analyzed the perception of
climate variability and change by fisher-folks, the attitude of fisher-folks toward the weather forecast
and the adoption rate of the use of the weather forecast as well as the factors determining its use in
Senegal. To this end, 576 fisher-folks belonging to 41 local fishing committees along the coastal areas
were surveyed and focus group discussions were organized with key informants. The adoption rate
was identified using the method of the average treatment effect (ATE) and the test of independency
(chi-square) was used to analyze the perceptions of and beliefs on climate change. The results
showed that 96% of fisher-folks perceive the change in the climate, though the effects are differently
appreciated across the coastline. The most frequently observed effects are: coastal erosion, change in
wind direction, increase in extreme swells and sea level rise. Nearly half of fisher-folks confirm
that they noticed these changes over the past five years. In the Southern Coast in particular, 40% of
fisher-folks stated that these changes happened 10 years ago. This statement is confirmed by the
qualitative data. More than 90% of the respondents ascertain the weather forecast before going to
fish, 63% regularly receive the weather forecast and 53% avoid going to sea during extreme events.
In addition, the results showed that if the weather forecast was made accessible to the majority of
fisher-folks, more than 83% would avoid going to sea during periods of extreme weather extreme
events, thus reducing significantly the number of fatalities. The best way to protect the fisher-folks
from the harmful effects of climate change is to ensure large-scale access to and use of accurate
weather forecasts
Using Seasonal Forecast as an Adaptation Strategy: Gender Differential Impact on Yield and Income in Senegal
The use of seasonal forecast has been demonstrated as a good option to reduce the effects
of climate variability in sub-Saharan African countries. However, its use, benefits and interests may
be different depending on gender. This paper aims at analyzing the gender differential impact of
the use of seasonal forecast on the main crop yields (rice, maize, sorghum, millet and groundnut)
and farm income in Senegal. We collected data from 1481 farmers (44% women) in four regions
of Senegal. We applied the counterfactual outcomes framework of modern evaluation theory to
estimate the local average treatment effect (LATE) of the use of the seasonal forecast on crop yield
and farm income. The results showed a significant impact of the use of the seasonal forecast (SF) in
the main crop yields and the agricultural income for farmers in Senegal. This impact varies according
to the sex and the type of the crops. The users (men and women) of the seasonal forecast gained
on average 158 kg/ha and 140 kg/ha more yield than the non-users, respectively, for millet and rice
crops. The impact of the use of SF is greater for men on millet (202.7 kg/ha vs. 16.7 kg/ha) and rice
(321.33 kg/ha vs
Achieving sustainable future objectives under uncertain conditions: Application of a learning framework to adaptation pathways in rural Mali
Adaptation Pathways have emerged as promising approaches for exploring sequences of actions to address
challenges in uncertain conditions. This study elaborates on how pathway approaches operate in practice by
applying a learning framework that identifies guiding propositions for successful adaptation pathways. The
framework is used to analyze a transformative scenario planning case study from rural Mali. Findings confirm
that adaptation pathways are highly context-specific, grounded in local institutions. The study also emphasizes
that the adaptation pathways process requires a sufficient timeframe to allow for cross-level interactions and
institutional changes to unfold as needed. The case demonstrates that the framework can be a useful tool for
reflexive learning and identifying gaps in a structured way during pathway development. However, it needs to be
adjusted to specific contexts to better capture the influence of and implications for power relations and social
inequality in future adaptation plans
Are perception and adaptation to climate variability and change of cowpea growers in Mali gender differentiated?
Understanding the gender dimension of climate change perception and choice of adaptation
strategies is crucial for policy recommendations that foster the development and integration
of gender-responsive climate-smart agricultural interventions into agricultural
development programs. This study determined the differences in the perception and choice
of adaptation strategies between men and women farmers in Cinzana in the Segou region
of Mali. The study used questionnaire interviews involving 260 farmers (49% women) and
focus group discussions for data collection. Data were analyzed using descriptive statistics
and multinomial logit model to understand the determinants of the level of adoption of
adaptation strategies. The results showed that, irrespective of gender, majority of farmers
perceived climate change as extended period of droughts, shortened duration of rains,
increased frequency of strong winds and increased day and night temperatures. While climate
change perception was similar between men and women, choice of adaptation strategies
differed significantly in most instances. Women farmers were generally low adopters
of crop and varieties-related strategies, soil and water conservation technics (contour farming,
use of organic manure), etc., compare to men. Notably, being the household head, age
and the availability of free labor were found to positively increased farmers’ probability of
adopting many adaptation strategies. The study recommends improving women’s access
and control of production resources (land, labor) as means to improving their adoption of
adaptation strategies
Options de Modèles d’Affaires pour Assurer la Durabilité de l’Utilisation des Services d’Information Climatique au Sénégal
USAID/CINSERE (Services d’information climatiques pour améliorer la résilience et la
productivité au Sénégal) est un projet de résilience qui vise à renforcer les capacités nationales
pour la production, l’accès et la diffusion efficiente d’informations météorologiques et climatiques
(IC) et de développer des stratégies pour une mise à l’échelle durable de l’utilisation des services
d’information météorologiques et climatiques (SIC) sur toute l’étendue du territoire national. Le
projet est financé par l’USAID et mis en oeuvre par le Programme de Recherche du CGIAR sur le
Changement Climatique, l’Agriculture et la Sécurité Alimentaire hébergé par ICRISAT
(CCAFS/ICRISAT) en collaboration avec l’ANACIM. La zone d’intervention du projet est celle
des projets Feed the Future (FtF) au Sénégal, notamment Naatal Mbay (clôturé en 2019),
Yaajeende (remplacé par Kawolor en 2018), ERA (remplacé par Youth in Agriculture en 2018) et
COMFISH (remplacé par Dekkal Geej en 2019).
Démarré en Mai 2016 pour une durée de trois ans (Jusqu’en mai 2019), le projet a bénéficié d’une
extension d’un an. Ainsi, cette première phase de l’USAID/CINSERE prend fin en avril 2020.
Durant presque quatre années de mise en oeuvre, des résultats assez probants ont été atteints tant
dans la production des SIC, la communication et l’utilisation de ces SIC, que dans le renforcement
des capacités des bénéficiaires à utiliser de façon efficiente ces SIC. Dans le souci de préserver les
acquis du projet et d’assurer une mise à l’échelle soutenue du système de développement et de
fourniture des IC en vue d’une utilisation durable des IC au Sénégal, l’USAID a recommandé
l’identification, le test, la validation et la mise en oeuvre de modèles économiques viables
impliquant des partenaires aussi bien du public que du privé (PPP). Le projet USAID/CINSERE
s’est donc inspiré des expériences et leçons apprises au Sénégal, au Ghana, au Mali, en Inde et en
Amérique Latine (Colombie) en matière de modèles économiques dans la fourniture des SIC pour
bâtir des modèles adaptés au contexte du Sénégal. Ce document présente les modèles identifiés
ainsi que les défis et perspectives
Accelerating Seed Germination and Juvenile Growth of Sorghum (Sorghum bicolor L. Moench) to Manage Climate Variability through Hydro-Priming
Agriculture in Mali, a country in SahelianWest Africa, strongly depends on rainfall and
concurrently has a low adaptive capacity, making it consequently one of the most vulnerable regions
to climate change worldwide. Since early-season drought limits crop germination, and hence growth,
ultimately yield during rain-fed depending on production is commonly experienced nowadays in
Mali. Germination and establishment of key crops such as the staple sorghum could be improved
by seed priming. The effects of hydro-priming with different water sources (e.g., distilled, tap, rain,
river, well water) were evaluated respectively for three priming time durations in tepid e.g., at 25C
(4, 8, and 12 h) and by hot water at 70C (in contrast to 10, 20, and 30 min.) in 2014 and 2015. Seed
germination and seedling development of nine sorghum genotypes were monitored. Compared
to non-primed seed treatments, hydro-priming significantly [p = 0.01] improved final germination
percentage, germination rate index, total seedling length, root length, root vigor index, shoot length,
and seedling dry weight. The priming with water from wells and rivers resulted in significant higher
seed germination (85%) and seedling development, compared to the three other sources of water.
Seed germination rate, uniformity, and speed were enhanced by hydro-priming also. It is argued that
hydro-priming is a safe and simple method that effectively improve seed germination and seedling
development of sorghum. If used in crop fields, the above most promising genotypes may contribute
to managing early season drought and avoid failure of seed germination and crop failure in high
climate variability contexts
Towards gender-informed adaptation planning in the Sudanian zone of Mali
Understanding the linkages between gender and vulnerability is crucial for proposing
sustainable gender-responsive climate-smart solutions. This study compared the vulnerabilities of male (MHHH) and female household heads (FHHH) in the Sudanian zone
of Mali using Cinzana in the Segou region as a case study. We used semi-structured questionnaire interviews and focus group discussions for data collection. The questionnaires were randomly administered to 233 household heads (23% women). The Livelihood Vulnerability Index (LVI) method was used to assess vulnerability to climate change. The results showed that livelihoods in the Sudanian zone of Mali are vulnerable to climate change.
Female household heads (FHHH) were found to be more vulnerable. FHHH recorded higher
values for six out of the eight LVI major components used in the vulnerability assessment:
socio-demographic index, livelihood strategies index, social network index, food index, natural disasters and climate variability index and agricultural production system index. The study proposes a number of interventions for improving the adaptive capacity of FHHH to climate change and variability: improving access to financial resources, improving access to
radio for receiving weather information, encouraging FHHHs involvement in farmer-based
groups for peer-learning; and promoting the development of policy initiatives that ensure the
mainstreaming of gender into agricultural development programs
Transforming climate science into usable services: The effectiveness of co-production in promoting uptake of climate information by smallholder farmers in Senegal
Does the provision of weather and climate information services (WCIS) enhance farmer’s use of forecasts in
informing farm decisions? This paper assesses the effectiveness of the Multi-disciplinary Working Group (MWG)
– a WCIS co-production initiative in Senegal in influencing farmers uptake of weather and climate information
(WCI). WCIS are increasingly gaining importance and widely touted as critical in helping farmers adapt to
climate variability. While there have been various WCIS initiatives producing and translating climate data into
tailored information and knowledge in different parts of the world, there is hardly any rigorous evidence
assessing their effectiveness in improving uptake. In this assessment, we use innovative survey methods and
apply rigorous analytical approaches that control for self-selection bias to establish causal linkages between the
MWG and use of WCIS. Our findings indicate that MWGs are positively associated with farmers’ awareness,
access and uptake of WCI resulting in farm management responses depending on the type of information used.
The presence of MWGs generally increases farmer’s awareness of WCI by 18%, access by 12% and uptake by
10%. Furthermore, use of seasonal forecasts is generally associated with a higher proportion of farmers using
improved seed, fertilizers and manure, but negatively with crop diversification within MWG locations. This
suggests that participatory approaches in the provision of tailored climate information and advisory services can
lead to higher uptake and use among farmers in informing farm management responses for better adaptation to
climate change. We highlight lessons for improved evaluations of WCIS in future
Better before worse trajectories in food systems? An investigation of synergies and trade-offs through climate-smart agriculture and system dynamics
Food systems face multiple challenges simultaneously: provision to a growing population, adaptation
to more extreme and frequent climate change risks, and reduction of their considerable greenhouse gas (GHG)
emissions. Food system interventions and policies give rise to synergies and trade-offs that emerge over time due
to the dynamic nature and interconnections of system elements. Analysis of an entire food system is necessary to
identify synergies that bring simultaneous benefits and mitigate trade-offs, both short- and long-term.
OBJECTIVE: Our study aims to inform the sustainable transformation of food systems by identifying short- and
long-term synergies and trade-offs in the climate-smart village (CSV) Lawra-Jirapa in northern Ghana under the
current practices, technologies, policies, and trends of population growth, extreme events, and climate change
impacts
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