A maximum power point tracking scheme for a 1kw stand-alone solar energy based power supply

This paper elucidates one of the tracking schemes for a photovoltaic (PV) systems using Cuk converter operating in discontinuous inductor current mode (DICM) as an interface. A method for efficiently maximizing the output power of a solar panel supplying a load or battery bus under varying meteorological conditions is investigated and results presented therein. The incremental conductance (InCond) method of maximum power point tracking (MPPT) using the Cuks dc to dc converter operating in a discontinuous inductor current mode (DICM) was modeled and studied in relation to PV system interface. Also, laboratory setup was implemented based on the model. This was the main objective of the research. Similarly, the PV simulator was also modeled alongside with Cuk converter operating in DICM. MATLAB/SIMULINK software was used to carry out simulation test. With the incremental conductance method, the problem of sustained oscillation around the maximum power point of the solar panel which is the usual characteristic of the perturbation and observation method is essentially absent. The result disclosed that the power available for the load when MPPT was applied was 1.1 kW which gives a tolerance of 0.1% to the load it powers. But without MPPT, the available power is 0.9 kW using the same number of PV panels and batteries as back up. Hence, MPPT has 17.65% edge in power delivery over non-MPPT PV powered energy supply. An experimental prototype of a 1kW, 230V, 50Hz stand-alone solar based power supply with the incremental conductance scheme was successfully implemented using PIC 16F877 microcontroller, tested and results presented therein. The experimental results agreed with the simulated results.Keywords: Maximum Power point tracking, Cuk converter, Photovoltaic system, PIC 16F877A micro-controller, inverter, batteries

Development of a software solution for solar-PV power systems sizing and monitoring

Power systems sizing and monitoring are very important design components in determining the overall performance of solar-photovoltaic (PV) systems. These design components represent the pre-installation and post-installation stages of solar-PV systems planning respectively, and paying adequate attention to them can go a long way to increasing the working life of solar-PV system installations. The SolarHelper developed in this work is a small software solution package that monitors and records vital system variables that will give the state and performance of an existing solar-PV installation at any given time; and it is able to accurately provide a simulated output of the required battery storage capacity, and PV array size based on load demands

Effectiveness of Climate Change Adaptation Measures used by Women Garden Egg Farmers in Enugu State, Nigeria

This study investigated the effectiveness of climate change (CC) adaptation measures used by women in garden egg production in Enugu State, Nigeria.  Multistage sampling procedure was used to select Eighty respondents for the study. Data were collected through the use of semi-structured interview schedule and analyzed with descriptive statistical tools such as frequency count & percentage, mean scores and standard deviation. The major effects of climate change on the garden egg production were scarcity of adequate floral resources (M =3.00), increased spread of pests and pathogens ( M=2.78), reduced pollen production in flowers ( M=2.68), reduced behavior and distribution activities, increase garden egg susceptibility to pathogens and decreased quantity and quality of garden egg production (M =2.67) and others. The most effective adaptation strategies used by women in garden egg production were change of the sites for farming (M=2.97), establishment of water reserve and farming close to irrigated area (M=2.92). The identified constraints to adapting to the present climate change scenario included: unstable weather (M=3.00), unavailability of modern harvesting techniques (M=2.75), increased pest and disease pathogens (M=2.68), poor access to materials and equipment (M=2.63), among others.  Hence, this study recommends awareness and training of garden egg farmers on how to improve the effects of the adaptation measures

Effectiveness of Climate Change Adaptation Measures used by Women Garden Egg Farmers in Enugu State, Nigeria

This study investigated the effectiveness of climate change (CC) adaptation measures used by women in garden egg production in Enugu State, Nigeria.  Multistage sampling procedure was used to select Eighty respondents for the study. Data were collected through the use of semi-structured interview schedule and analyzed with descriptive statistical tools such as frequency count & percentage, mean scores and standard deviation. The major effects of climate change on the garden egg production were scarcity of adequate floral resources (M =3.00), increased spread of pests and pathogens ( M=2.78), reduced pollen production in flowers ( M=2.68), reduced behavior and distribution activities, increase garden egg susceptibility to pathogens and decreased quantity and quality of garden egg production (M =2.67) and others. The most effective adaptation strategies used by women in garden egg production were change of the sites for farming (M=2.97), establishment of water reserve and farming close to irrigated area (M=2.92). The identified constraints to adapting to the present climate change scenario included: unstable weather (M=3.00), unavailability of modern harvesting techniques (M=2.75), increased pest and disease pathogens (M=2.68), poor access to materials and equipment (M=2.63), among others.  Hence, this study recommends awareness and training of garden egg farmers on how to improve the effects of the adaptation measures

Effectiveness of Climate Change Adaptation Measures used by Women Garden Egg Farmers in Enugu State, Nigeria

This study investigated the effectiveness of climate change (CC) adaptation measures used by women in garden egg production in Enugu State, Nigeria.  Multistage sampling procedure was used to select Eighty respondents for the study. Data were collected through the use of semi-structured interview schedule and analyzed with descriptive statistical tools such as frequency count & percentage, mean scores and standard deviation. The major effects of climate change on the garden egg production were scarcity of adequate floral resources (M =3.00), increased spread of pests and pathogens ( M=2.78), reduced pollen production in flowers ( M=2.68), reduced behavior and distribution activities, increase garden egg susceptibility to pathogens and decreased quantity and quality of garden egg production (M =2.67) and others. The most effective adaptation strategies used by women in garden egg production were change of the sites for farming (M=2.97), establishment of water reserve and farming close to irrigated area (M=2.92). The identified constraints to adapting to the present climate change scenario included: unstable weather (M=3.00), unavailability of modern harvesting techniques (M=2.75), increased pest and disease pathogens (M=2.68), poor access to materials and equipment (M=2.63), among others.  Hence, this study recommends awareness and training of garden egg farmers on how to improve the effects of the adaptation measures

Multilocus microsatellite analysis of European and African Candida glabrata isolates

This study aimed to elucidate the genetic relatedness and epidemiology of 127 clinical and environmental Candida glabrata isolates from Europe and Africa using multilocus microsatellite analysis. Each isolate was first identified using phenotypic and molecular methods and subsequently, six unlinked microsatellite loci were analyzed using automated fluorescent genotyping. Genetic relationships were estimated using the minimum-spanning tree (MStree) method. Microsatellite analyses revealed the existence of 47 different genotypes. The fungal population showed an irregular distribution owing to the over-representation of genetically different infectious haplotypes. The most common genotype was MG-9, which was frequently found in both European and African isolates. In conclusion, the data reported here emphasize the role of specific C. glabrata genotypes in human infections for at least some decades and highlight the widespread distribution of some isolates, which seem to be more able to cause disease than others.This research was supported in part by the EU Mare Nostrum (EUMN-III Call) program of the European Union, grant agreement number 2011-4050/001-EMA2. Dr Sanae Rharmitt was the recipient of a scholarship (10 months) signed within the EUMN program for PhD students (F.S. 1.04.11.01 UORI) under the supervision of Prof Orazio Romeo.info:eu-repo/semantics/publishedVersio

Assessment of the physical characteristics and stormwater effluent quality of permeable pavement systems containing recycled materials

This paper evaluates the physical characteristics of two recycled materials and the pollutant removal efficiencies of four 0.2 m2 tanked permeable pavement rigs in the laboratory, that contained either natural aggregates or these recycled materials in the sub-base. The selected recycled materials were Crushed Concrete Aggregates (CCA) and Cement-bounded Expanded Polystyrene beads (C-EPS) whilst the natural aggregates were basalt and quartzite. Natural stormwater runoff was used as influent. Effluent was collected for analysis after 7–10 mins of discharge. Influent and effluent were analysed for pH, Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), Electroconductivity (EC), turbidity, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Nitrate-Nitrogen (NO3-N), reactive phosphorous (PO43-) and sulphates (SO42-). Both CCA and C-EPS had suitable physical properties for use as sub-base materials in PPS. However, C-EPS is recommended for use in pavements with light to no traffic because of its relatively low compressive strength. In terms of pollutant removal efficiencies, significant differences (p 0.05) were found with respect to TSS, turbidity, COD and NO3-N. Effluent from rigs containing CCA and C-EPS saw significant increases in pH, EC and TDS measurements whilst improvements in DO, TSS, turbidity, COD, PO43- and SO42- were observed. All mean values except pH were, however, within the Maximum Permissible Levels (MPLs) of water pollutants discharged into the environment according to the Trinidad and Tobago Environmental Management Authority (EMA) or the United States Environmental Protection Agency (US EPA). In this regard, the CCA and C-EPS performed satisfactorily as sub-base materials in the permeable pavement rigs. It is noted, however, that further analysis is recommended through leaching tests on the recycled materials