3d Approach Of Spectral Response For A Bifacial Silicon Solar Cell Under A Constant Magnetic Field

A three-dimensional study is made to improve the theoretical approach of spectral response of bifacial polycrystalline silicon solar cells. This study has allowed taking into account new parameters like grain size and grain boundaries recombination velocity, which reduce the cell efficiency. Losses in emitter region and external magnetic field are also being taken into account in order to perfect the description of measured spectral response. Then the new analytical expressions of carrier, photocurrent and short circuit densities are produced for front side and rear side illuminations. Homemade software based on the new analytical expressions of internal quantum efficiency is used to fit the experimental data

Candidate fodder trees and shrubs for sustainable ruminant production in northern Ghana

A survey was done to document preferred browse plants and farmers’ knowledge about them for sustainable ruminant production in northern Ghana. The study was done in Jirapa and Lawra Districts of Upper West Region of Ghana. A questionnaire was used to interview 50 farmers per district. Tables and graphs were drawn to summarize results. Ruminant production was a predominantly male occupation (p=0.032). It was also in the domain of the lowly educated (p=0.003). Ninety-seven percent (97%) of the respondents had goats with about half of them having sheep and 17% owning cattle. The overriding (99%) reason for rearing ruminants was to serve as a source of income. In the dry season, ruminants were kept on free range. In the wet season, small ruminants were tethered with or without feed supplementation. A total of 34 browse plants were identified and the most frequently browsed were Fadherbia albida, Ficus sycomorus gnaphalocarpa, Afzelia africana, Pterocarpus erinaceus, Combretum molle and Annona senegalensis. Paramount among the challenges faced by the owners were limited grazing land, feed scarcity and theft. Apart from being fodder sources, the identified browse species were soil improvers, medicinal and human food sources. All respondents grew crops and the most frequently cultivated crops were groundnut, maize, cowpea, bambara groundnuts, sorghum, millet, rice and yam in this decreasing order. Ninety percent (90%) of the respondents fed crop residue to their animals, with the commonest, groundnut haulm, fed by about 80% of the respondents. Twenty-eight different types of trees/shrubs were identified on respondents’ farms

Assessing the Climate-Smartness of the West Africa Agricultural Productivity Programme (WAAPP): What can we learn from Benin, Guinea, Niger, Togo and Chad projects?

Agriculture is the most important sector of the national economies in West Africa. However, the agricultural sector is faced with numerous challenges (declining soil fertility and land degradation, adverse climate change manifestations, demographic pressure, market instability and incidence of crop pests and diseases, etc.), compromising its ability to be a driving engine out of food insecurity and poverty. With the growing challenge of climate change and variability in West Africa, the agricultural production and food systems must undergo significant transformations to meet the interlinked challenges of achieving sustainability, increasing food security and responding to climate change. Climate-smart agriculture (CSA) is proposed as a solution to transform and reorient agricultural systems to support food security under the new realities of climate change

Survival and growth responses of Jatropha curcas L. to three restoration techniques on degraded soils in Burkina Faso

Land degradation is a major problem in the Sahelian countries. Erosion control through establishment of vegetation cover is at important strategy to reverse the trend. Our research objective was to analyse the e-ffects of three restoration techniques on Jatropha curcas L. seedlings growth and survivorship. Were conducted two separate field trials, involving the sowing and planting of J. curcas, in which several different soil restoration techniques were applied. The trial was monitored using a ran-domized block study design over a period of two years. The design included ten different treatments, six in the sowing trial and four in the planting trial, each with three replicates. In the first experiment, growth rate was found to be significantly higher in the Sub-Soiling treatment, that received additional organic matter than other treatments. However, overall survival rate was low (18%). In the second experiment, the Half-moon treatment yielded a significantly higher growth both in height (df = 3, F = 56.74, p < 0.05) and diameter (df = 3, F = 31.76, p < 0.05) and survival rate compared to those of the other treatments (df = 3, F = 50.4, p < 0.05). In conclusion, planting seedlings produced a greater survival rate than sowing seeds. Among tested the soil restoration and water conservation techniques the Half-moon technique was found as the most effective. This is recommended to be used for improving the revegetation of J. curcas in the future

In vivo digestibility of six selected fodder species by goats in northern Ghana

An in vivo digestibility trial was conducted to evaluate the digestibility of six forages. These were selected indigenous browse species and groundnut haulms in Lawra and Jirapa Districts of the UpperWest Region of Ghana. Groundnut haulms served as a control due to its known good digestibility in small ruminants. Thirty West African Dwarf (WAD) young castrated billy goats with a mean age of 8 months were used. The average live body weight was 8.9 ± 0.1 kg. The animals were randomly assigned to the six treatments and replicated five times in a completely randomized design. They were confined in metabolism cages. The adaptation period was 3 weeks after which data was taken for 10 days. The treatments were the leaves and tiny twigs of T1 Annona senegalensis, T2 Ficus gnaphalocarpa, T3 Pericopsis laxiflora, T4 Pterocarpus erinaceus, T5 Afzelia africana, and T6 (control) Arachis hypogaea. Feed intake, faecal matter and urine output were measured. The results indicated that dry matter (DM) contents of the feedstuffs were less than 50% but crude protein (CP) contents were higher than the minimum required for sustaining ruminants. Neutral and acid detergent fibre contents were high, and F. gnaphalocarpa, in particular, contained a higher level of phosphorus (P). The amounts of feed intakes were typical of most fodder species with the exception of P. laxiflora and P. erinaceus, which were lower (P < 0.05). The apparent digestibility values were also typical of most fodder species but the digestibility of A. africana fibre appeared to be lower. Nitrogen retention was positive for all test species with the exception of P. laxiflora, which was negative. Mortality was recorded in animals on P. laxiflora, and the rate was high. Pericopsis laxiflora leaves, even though morphologically similar to the leaves of P. erinaceus, were not a suitable fodder. Ficus gnaphalocarpa appeared to be the overall best fodder species in terms of nutrient uptake

Prioritizing investments for climate-smart agriculture: Lessons learned from Mali

Agricultural productivity and growth in Mali are under threat from erratic rainfall, resulting in more frequent dry years. The national economy is vulnerable to climate change due to 50% of the gross domestic product coming from the agricultural sector and 75% of the population living in rural areas. The Climate-Smart Agriculture (CSA) concept arises from a need to provide innovative solutions towards the complex and integrated goals of increasing yields, improving resilience, and promoting a low emissions agricultural sector. A major challenge for policymakers to operationalize CSA is the identification, valuation (cost-benefit), and subsequent prioritization of climate-smart options and portfolios (groups of CSA options) for investment. This paper presents the process, results, and lessons learned from a yearlong pilot of the Climate-Smart Agriculture Prioritization Framework (CSA-PF) in Mali. Key national and international stakeholders participated in the co-development and prioritization of two CSA portfolios and related action plans for the Malian Sudanese zone. Initial steps towards outcomes of the process include inclusion of prioritized CSA practices in ongoing development projects and prompting discussion of modifications of future calls for agricultural development proposals by regional donors

Understanding gender dimensions of agriculture and climate change in smallholder farming communities

In Uganda, Ghana and Bangladesh, participatory tools were used for a socio-economic and gender analysis of three topics: climate-smart agriculture (CSA), climate analogue approaches, and climate and weather forecasting. Policy and programme relevant results were obtained. Smallholders are changing agricultural practices due to observations of climatic and environmental change. Women appear to be less adaptive because of financial or resource constraints, because of male domination in receiving information and extension services and because available adaptation strategies tend to create higher labour loads for women. The climate analogue approach (identifying places resembling your future climate so as to identify potential adaptations) is a promising tool for increasing farmer-to-farmer learning, where a high degree of climatic variability means that analogue villages that have successfully adopted new CSA practices exist nearby. Institutional issues related to forecast production limit their credibility and salience, particularly in terms of women’s ability to access and understand them. The participatory tools used in this study provided some insights into women’s adaptive capacity in the villages studied, but not to the depth necessary to address women’s specific vulnerabilities in CSA programmes. Further research is necessary to move the discourse related to gender and climate change beyond the conceptualization of women as a homogenously vulnerable group in CSA programmes

Climate change adaptation in agriculture: practices and technologies. Messages to the SBSTA 44 agriculture workshops

In 2014 the United Nations Framework Convention on Climate Change (UNFCCC) Subsidiary Body for Scientific and Technological Advice (SBSTA), as part of its mandate to consider issues related to agriculture, decided to invite submissions from parties and observers, covering four topics, in 2015 and 2016. Of the two topics for consideration in 2016, one relates to ‘identification and assessment of agricultural practices and technologies to enhance productivity in a sustainable manner, food security and resilience, considering the differences in agro-ecological zones and farming systems, such as different grassland and cropland practices and systems’. In this info note we provide a brief overview of key practices and technologies. A twinned info note considers higher-level measures of adaptation in agriculture, such as policies and institutions

BER Reduction for mQAM High-Speed Tranmission in Optical Fiber Networks Using Convalutional BCH, RS and LDPC Error Correcting Codes

A comparative study of digital m-ary Quadrature Amplitude Modulation (mQAM) channel coding signals for optical high-speed transmission is presented in this article. The needs to transmit information at high speed are topical and relevant to the images, the sounds, and data of any kind, etc. The photonic networks are the subject of much research on the application in optical domain of techniques already used in wireless networks such as mQAM digital modulations and error correcting codes. The mQAM digital modulations interest lies in the fact that they are now being used as subchannel modulation techniques in other advanced modulations such as Othogonal Frenquency Division Multiplexing (OFDM). Indeed, OFDM using mQAM modulation seems to be a good candidate in high speed networks. This allows considering transmission systems at very high speeds in optical transmission networks. The performance of channel coding is based on the estimation of the Bit Error Rate (BER) implementing techniques of Convolutional codes, Bose Chaudhuri Hocquenghem (BCH) codes, Reed-Solomon (RS) codes and Low Density Parity Check (LDPC) codes in a 10Gbps transmission. The BER is estimated as a function of the OSNR and also as a function of the transmission distance.The study was conducted in a software cosimulation environment with VPITransmissionMaker and Matlab software. The simulation results showed that error correcting codes and particularly LDPC codes are effective and provide satisfactory solutions to reduce the BER by fighting against optical transmission channel disturbances such as chromatic dispersion and nonlinearities.Keywords: mQAM, broadband, BER, optical fiber, error correcting codes