Design of an optimum MPPT controller for solar energy system

Solar energy is compared to be the best potential source of renewable energy in Pacific region. For this reason a photovoltaic cell is needed to harvest this kind of energy, gathering the most of it and the PV having a good efficiency. The maximum efficiency is achieved when the PV works at its Maximum Power Point which entirely depends on the irradiation and temperature. This paper proposes a new design of hybrid Maximum Power Point Tracking and a comparative study is made with various existing MPPT techniques which include Perturb and Observe method, Incremental Conductance and Fuzzy Logic. From the comprehensive comparison study between existing MPPT technique and the proposed MPPT technique/theory, a hardware setup was demonstrated to verify the proposed design by charge controller in photovoltaic systems to which maximize the output power under various lighting conditions. The design is based on the computed results using the buck-boost DC-DC conveter. From the simulation, the proposed method tends to show better performance with almost no oscillations around the MPP

Utilization of lignocellulosic waste for ethanol production: Enzymatic digestibility and fermentation of pretreated shea tree sawdust

Enzymatic hydrolysis and fermentation methods were evaluated on alkaline peroxide pretreated shea tree sawdust conversion to ethanol. Optimum pretreatment conditions of 120 oC reaction temperature, 30 min reaction time, and 20 mL L−1 of water hydrogen peroxide concentration (1%(v/v)H2O2) solubilized 679 g kg−1 of hemicellulose and 172 g kg−1 of lignin. 617 g kg−1 cellulose was retained in the solid fraction. The maximum yield of reducing sugar with optimized enzyme loadings by two enzyme preparations (cellulase and β-glucosidase) was 165 g kg−1 of dry biomass. The ethanol yield was 7.35 g L−1 after 72 h incubation period under the following conditions: 2% cellulose loading, enzyme concentration was 25 FPU (g cellulose)−1 loading, yeast inoculums was 10% (v/v), 32 oC, and pH 4.8. The pretreatments gave information about the hindrances caused by lignin presence in lignocellulosic materials and that hemicelluloses are better hydrolyzed than lignin, thereby enhancing enzymatic digestibility of the sawdust materia

Hydrogen peroxide and lime based oxidative pretreatment of wood waste to enhance enzymatic hydrolysis for a biorefinery: Process parameters optimization using response surface methodology

Response surface methodology (RSM) was adopted for the optimization of process variables in the alkaline peroxide oxidation (APO) pretreatment of Vitellaria paradoxa sawdust based on central composite design (CCD) experiments. A 23 five level CCD with central and axial points was used to develop a statistical model for the optimization of process variables. Maximum response for the pretreatment was obtained when applying the optimum values for temperature (150 �C), time (45 min), and 1% (v/v) H2O2. At the optimum conditions, up to 70% of the initial hemicellulose was removed in treatments, which also caused some delignification (up to 11% of the initial lignin was removed), whereas cellulose was almost quantitatively retained in the solid phase. Alkaline peroxide assisted wet air oxidation (APAWAO) pretreatment at the optimum conditions resulted in enrichment up to 60% cellulose content along with solubilization of 80% hemicellulose and 17% of lignin initially present in the raw sawdust. Reducing sugars yield after 72 h enzymatic hydrolysis of pretreated biomass at optimized APO conditions was 177.89 mg equivalent glucose g�1 dry biomass. Addition of 10 bar air pressure at the optimized pretreatment conditions increased the sugars yield to 263.49 mg equivalent glucose g�1 dry biomass

Influence of the fruit and leaf extract of Psidium guajava linn. on wound healing in Wistar rats.

Abstract: Leaf extract of guava (Psidium guajava Linn.) has been reported to promote wound healing in traditional medicine but there is paucity of information in literature regarding similar activity of fruit extract. Therefore, the present study was planned to investigate the influence of leaf and fruit extract of Psidium guajava Linn. on re-sutured incision, excision, and dead space wounds in male Wistar rats. Wounds were inflicted under light ether anesthesia aseptically. Control animals received vehicle and other groups received aqueous extract of either leaf or fruit orally in the dose of 500mg/kg/day for a period of 10 days in the incision and dead space wounds, whereas treatment continued till complete wound closure in excision wound model. On the 10 th day after estimation of breaking strength of the resutured incision wounds, animals were sacrificed and granulation tissue from dead space wounds were used to estimate the breaking strength and hydroxyproline content. Quantification of granulation tissue and histopathological slides were also carried out. Wound closure rate, epithelization time and scar features were studied in the excision wounds from the day of extract administration till complete closure of wounds. Only aqueous fruit extract significantly (P<0.01) promoted the healing process in all three wound models studied. Histopathological slides revealed increased collagen content and granulation tissue in fruit extract treated group as compared to that of control. In contrast, the leaf extract delayed excision wound healing and had no effect on incision and dead space wounds. These findings merit, clinical evaluation of Psidium gaujava fruit

^{63,65}Cu NMR and NQR evidence for an unusual spin dynamics in PrCu_2 below 100 K

We report the results of a $^{63,65}$Cu NMR/NQR study probing the intermetallic compound PrCu$_2$. The previously claimed onset of magnetic order at 65 K, indicated in a $\mu$SR study, is not confirmed. Based on our data we discuss different possible reasons for this apparent discrepancy, including a non negligible influence of the implanted muons on their environment. Competing dipolar and quadrupolar interactions lead to unusual features of the magnetic-ion/conduction-electron system, different from those of common intermetallics exhibiting structural or magnetic instabilities.Comment: 8 pages, 7 figures, submitted to Phys Rev

Optimization of pretreatment conditions using full factorial design and enzymatic convertibility of shea tree sawdust

In this study alkaline wet air oxidation (WAO), alkaline peroxide assisted wet air oxidation (APAWAO), and enzymatic hydrolysis methods were evaluated for conversion of wood residue (sawdust) to reducing sugars. Cellulose content, hemicellulose solubilization, and lignin removal forWAOpretreatment conditions were optimized by statistical analysis using a 23-full factorial design with reaction temperature, air pressure, and reaction time as the process parameters. An optimum WAO condition of 170 �C, 1.0 MPa, 10 min was predicted and experimentally validated to give 518 g kg-1 cellulose content, 580 g kg-1 hemicellulose solubilization, and 171 g kg-1 lignin removal in the solid fraction. About 7 g L-1 reducing sugars was detected in the pretreated liquid fraction. Presoaking the dry raw biomass for 24 h in H2O2 followed by wet air oxidation (APAWAO) at the optimized conditions resulted in enrichment up to 683 g kg-1 cellulose content in the solid fraction along with solubilization of 789 g kg-1 hemicellulose and 280 g kg-1 lignin removal. The yield of reducing sugars from WAO optimized conditions by two enzyme preparations (cellulase and b-glucosidase) was 131mgg-1 of dry substrate, while the APAWAO yielded 274mgg-1. Pretreatments used in this study showed to have a disrupting effect on the lignocellulosic biomass, making the treated materials accessible for enzymatic hydrolysis. The combination of presoaking inH2O2 before WAO pretreatment and enzymatic hydrolysis was found to give the highest sugar yield

Treatment of waste gas containing diethyldisulphide (DEDS) in a bench scale biofilter

Waste gas containing diethyldisulphide (DEDS) is generated from various industries including pulp and paper, refinery, rayon and molasses based distilleries, etc. DEDS has odour threshold detection with an average concentration of 10�9 mg/m3 at 25 �C. DEDS is toxic to bacteria, fungus and also to mammals when exposed for a long period. Waste gas containing DEDS require proper treatment prior to discharge into the environment. DEDS containing waste gas was treated in a biofilter, packed with compost along with wooden chips and enriched with DEDS degrading microorganisms. The biofilter could remove DEDS to the extent of 94 ± 5% at a loading of 1.60 g/m3/h with an empty bed retention time of 150 s. At optimal operating conditions, the average moisture content required by the biofilter was in the range of 60–65%. The biodegradative products of DEDS were thiosulphate and sulphate

Energy efficient—Advanced oxidation process for treatment of cyanide containing automobile industry wastewater

Destruction of cyanide (CN) from an automobile industry wastewater by advance oxidation process (AOP) has been evaluated. The operating conditions (in an digenously designed photoreactor) for three different treatment strategies have been optimized. The treatment strategies involved use of, ultra violet light (UV), hydrogen peroxide (H2O2) and ozone (O3) in various combinations. Treatment of automobile industrywastewater (250 mg/L CN) showed fastest CN destruction, which was significantly (P < 0.05) faster than that observed with syntheticwastewater (with similar CN concentration). A combined application of H2O2/O3 was found to be the best option for maximum CN destruction. This treatment allows CN to reach the regional/international limit (of 0.02 mg/L) for safe industrial wastewater discharges to the receiving water bodies. The specific energy consumption by the photoreactor following this treatment was comparable to that obtained by conventional treatments, which use photocatalyst. Since the present treatment does not use catalyst, it provides an excellent energy efficient and economical option for treatment and safe disposal of CN containing industrial wastewater. © 200

Treatment of waste gas containing low concentration of dimethyl sulphide in a high performance biotrickling filter

1018-1023A bench-scale biotrickling filter was operated in the laboratory for the treatment of dimethyl sulphide (DMS). The biotrickling filter was packed with pre-sterilized polyurethane foam and seeded with biomass developed from garden soil enriched with DMS. The biotrickling filter was operated for the generation of process parameters. The biotrickling filter could remove an average removal efficiency of 40.95 % at an effective bed contact time of 84 sec with an average loading rate of 0.56 mg/m3/h. Evaluation of microbiological status of the biotrickling filter indicated the presence of other bacterial cultures viz. Paenibacillus polymyxa, and Bacillus megaterium, besides Bacillus sphaericus.</i

Growth and biochemical response of an indigenous oleaginous microalga <em>Scenedesmus obtusus</em> cultivated in outdoor open ponds

40-49Understanding the response of microalgae to outdoor culture conditions is necessary for the development of large open pond cultivation system for various value added applications. In this context, we evaluated the response of an indigenous oleaginous green microalga Scenedesmus obtusus CFR 1-09/FW to outdoor culture conditions. The microalga was cultivated in open ponds at various culture depths under nutrient replete condition. The pond with 3 cm culture depth showed highest biomass productivity (49.05±11.74 mg L-1 day-1). The high surface solar irradiance (1831 µmol m-2 s-1) led to a decrease in chlorophyll content (from 12.21 to 4 µg mg-1). The long duration exposure to lower temperatures (≤20°C) during night led to an increase in poly unsaturated fatty acids (PUFAs) content (47.21±2.83% w/w mass fraction of FAME). The omega-3 alpha linolenic acid (ALA) content rose significantly reaching 31.01±3.79% (w/w) mass fraction of FAME. The high content of carbohydrate (23.4±0.64% w/w), protein (37.62 ± 2.15% w/w), lipid (21.55±1.43% w/w), palmitic acid (30.97±4.02% w/w mass fraction of FAME) and ALA in outdoor cultures makes this microalga a potential candidate for outdoor cultivation for food and feed applications. The study provides valuable insights for developing outdoor open pond cultivation protocol