Capacity Factor Values Research Articles

Defining Capacity Factor by Weibull Shape Parameter and Mean Wind Speed

This workmodels capacity factor in terms of wind turbine operating characteristics, mean wind speed, and shape parameter of Weibull probability density function. The methodology used involves fewer parameters than have been used by other workers. We have used a nondimensional speed parameter ( x) as the ratio of the wind speed ( V) to the mean wind speed ( Vm). The operating characteritics of a megawatt wind turbine cut-in ( Vin), rated ( Vr) and cut-out ( Vout) speeds are divided by Vm, resulting into nondimensional speeds: xin, xr, and xout, respectively. Similarly, the Weibull scale parameter is also transformed by the Vm. The final model of the capacity factor constitutes four variables: xin, xr, xout and k. The analysis of model shows that, in general, low values of nondimensional speed xr results into higher values of capacity factor. The shape parameter also influences the value of capacity factor. High values of shape parameter provides, in general, low value of capacity factor. For example, a turbine designed for shape parameter of about 2 if installed at a site where the shape parameter is about 4 or more than the value of capacity factor may reduce by almost 10%. The analysis also shows that if one wishes to achieve higher values of capacity factor for a turbine desined for k = 2 to k = 4 would necessitate increase in the mean wind speed of the new site ( k = 4).

Seismic Uplift Capacity of Horizontal Strip Anchors Using a Modified Pseudodynamic Approach

The uplift capacity of shallow horizontal strip anchors embedded in cohesionless soil has been obtained under seismic conditions. The limit equilibrium approach with log spiral failure surface together with modified pseudodynamic seismic forces has been adopted. In this modified pseudo dynamic approach, the soil is assumed to behave as a viscoelastic material overlying a rigid stratum and subjected to harmonic horizontal acceleration. This modified methodology satisfies the zero-stress boundary condition at the free ground surface. In the present methodology, the amplification of seismic acceleration depends on the soil properties and can be evaluated; hence, there is no need for assumption of any amplification value as is usually done in the literature. It is observed that the seismic acceleration distribution along the depth is highly nonlinear. The net seismic vertical uplift capacity factor for a unit weight component of soil (Fγd) is estimated. The results under static and seismic conditions are determined for various combinations of input parameters, such as soil friction angle, embedment ratio, and seismic acceleration. It is observed that the design value of Fγd decreases significantly with an increase in seismic acceleration. As expected, the seismic uplift capacity increases with an increase in embedment ratio and soil friction angle. Results in terms of nondimensional net seismic uplift capacity factor are presented in graphical form. In addition, the present results are compared and found to be in good agreement with a very few available similar results in literature. The present study reveals the lowest critical design values of seismic uplift capacity factor that may be used in seismic design of shallow strip anchors.

Viability study of grid-connected solar PV system in Ethiopia

This study explored the potential of grid-connected solar PV power generation in Ethiopia. Overall, 35 locations were assessed for their technical potential considering a 5MW PV power plant in each site. Input data sources for the study include the National Meteorological Agency of Ethiopia and the Surface Meteorology and Solar Energy Dataset of NASA. Both HOMER and RETScreen software were employed in the study. It was found in the study that the average value of PV power plant capacity factor of the different locations considered is 19.8%, and the mean value for the electricity exported to the grid is 8674MWh/year. Furthermore, economic viability study of a 5MW PV grid-connected power plant in Addis Ababa area was further conducted. Financial indicators showed that the proposed solar PV system is economically viable, but it may not be sufficiently attractive for commercial investors unless an incentive mechanism is introduced. Further scenario analysis indicated that the upcoming feed-in tariff law for solar PV power generation (which is not yet introduced) may influence the investment decision of the private sector. With the proposed system, up to 7658MWh electricity can be generated and a minimum of 1089tons of greenhouse gas emission can be reduced annually.

Three-level response surface full-factorial design: advanced chemometric approach for optimizing diclofenac sodium-imprinted polymer

The present research work was undertaken to optimize the template:monomer:cross-linker ratio of the diclofenac sodium block molecularly imprinted polymer with respect to the molecular recognition properties. A three-level full-factorial design was employed. This is of great interest because applying this approach instead of traditional methods would be expected to improve validation of the optimum and consumed time. Imprinted polymers with selected ratios and the control polymers were synthesized by precipitation polymerization method and the values of rebind capacity and imprinting factor calculated after performing batch rebinding experiments. The predicted optimum ratios of (1:8:40) and (1:4:40) were found by applying the three-dimensional surface plots for rebind capacity and imprinting factor. The optimized imprinted polymers and their control polymers were produced. These polymers were evaluated using equilibrium binding experiments and finally the optimum molar ratio of (1:8:40) chosen. Batch rebinding experiments were carried out to evaluate the binding and selectivity properties of the optimized polymer. A heterogeneous nature of the binding sites was found based on the Scatchard plot. The selectivity study of imprinted polymers demonstrated a 24 % cross-reactivity towards meclofenamate sodium, but less than 2 % towards fenoprofen calcium.

Estimation of seismic uplift capacity of horizontal strip anchors using pseudo-dynamic approach

In this paper, an analytical method to compute the vertical uplift capacity of horizontal strip anchors under both static and seismic conditions is described by using limit equilibrium method and Kötter’s equation. For seismic forces, pseudo-dynamic approach is used to obtain the net seismic vertical uplift capacity factor for unit weight component of soil (Fγd) by considering the distribution of soil reaction on the simplest planar failure surface through the use of Kötter’s equation. Results under static and seismic conditions are determined for various combinations of input parameters, like soil friction angle, embedment ratio, soil amplification and both horizontal and vertical pseudo-dynamic seismic accelerations. It is observed that Fγd decreases significantly with increase in both horizontal and vertical seismic accelerations and soil amplification. As expected, the seismic uplift capacity increases with increase in embedment ratio and soil friction angle. Results in terms of non-dimensional net seismic uplift capacity factor are presented in graphical form. Present results are compared and found in good agreement with few similar results available in literature. Present study reveals lowest critical design values of seismic uplift capacity factor which can be used in seismic design of anchors.

Wind Energy Potential Investigation and Micrositting in Langkawi Island, Malaysia

The aim of this study was to predict the wind energy potential over the Langkawi Island, Malaysia. The wind data for year 2009 was collected from Malaysia Meteorology Department (MMD) and then extrapolated to the hub heights of various turbines. Wind turbines with rated powers between 1 kW and 110 kW were chosen for annual energy production calculations and best fitted ones were used for the micrositting analysis. In this study, the turbine with 22 kW rated power with hub height 30 m was selected based on its best value of capacity factor. The wind speed frequency per year is highly peaked in the range 1–6 m/s, this indicate that most of the wind speed at Langkawi Island lies in this range. The ‘WAsP’ and ‘WindPRO’ softwares were used for the wind statistics and energy calculations. Calculated energy production of located 10 turbines with total capacity of 0.22 MW was 111.1 MWh. Suitable sites were selected according to the created wind power and energy maps. The future cost of maintenance and the status of area either its reserved or conserved by the government were the factors that be considered for selection of site area.

An Investigation of Wind Characteristics and Techno-Economic Evaluation of Wind Energy in Nigeria

In this study, wind characteristics and techno-economic analysis in six selected locations in the northern (Jos, Kano, Sokoto and Maiduguri) and southern (Lagos and Enugu) regions of Nigeria using wind speed data at 10m height collected over a period of seventeen years (1990-2006) were analyzed. The techno-economic evaluations of electricity generation from four commercial wind turbine models used for electricity generation located at these sites were evaluated. The wind speed data analysis shows that the sites evaluated are good locations for wind potential in electricity generation from wind. The yearly energy output, the capacity factor and the wind energy cost per unit of electricity generated by the selected wind turbines are calculated. In terms of energy production, the results show that Plateau is best location for harnessing wind power for electricity generation with an average wind power density of 713.95W/m2. The maximum energy output was obtained for De wind 48 turbine model. The capacity factor values are found to vary from a minimum of 21% to maximum of 28% for this research work. The results also shows that the cost per kWh of electricity generation using these turbines is between 0.493 – 0.606$kWh.

Evaluation of the Chromatographic Performance of di-and tri-amide Calix[4]arene Derivatives Bonded Silica Stationary Phases

The chromatographic behaviors of di- and tri-amide derivatives of calix[4]arene immobilized onto aminopropyl silica gel (Calix-SP1 and Calix-SP2) were evaluated by using some aromatic hydrocarbons and aromatic amines in the HPLC. The effect of organic modifier content, pH and column temperature on retention and selectivity of these compounds were investigated. The results of the study of column temperature influence have shown a high linear correlation between the logarithm of capacity factor and reciprocal value of absolute temperature for each studied analyte. The thermodynamic parameters implicated in chromatographic retention were determined using the van't Hoff method. The retention mechanism was also discussed. The results indicated that the stationary phases behave like a reversed-phase packing. However inclusion, hydrophobic, hydrogen bonding, and π–π interactions seem to be involved in separation process.

Estimation of Electricity Generation in Libya Using Processing Technology of Wind Available Data: The Case study in Derna

This paper is concerned with the processing technology of wind available data as a means to estimate the electricity generation in Derna site - Libya, which are located on the coast of Mediterranean Sea. The work presented long term wind data analysis in terms of annual, seasonal and diurnal variations at these sites. The wind speed and wind direction each 3hours data for a period of 10 years between 2000 and 2009 were used in the analysis. Weibull parameters at different heights has been studied and used to describe the distribution and behavior of wind speed and their frequencies. Wind turbine energy production at different heights has been calculated using a Weibull distribution (Weibull Statistics Techniques). The total energy output per year from the wind machines of different sizes and at different hub heights were compared. This research work revealed that the lower rated speed for the wind energy conversion system (WECS) of the same height, the higher the capacity factor values, in most cases. This work used also a new analytical method of (Spena & Ahwide's method) for the estimation of the available wind energy potential. The results of both previous mentioned method's were compared. Moreover, the expected cost in $ Dollar/kWh for both wind machines have been calculated, which have different characteristics but the same power level of 1650kW. It was hoped that the data analysis can help to identify good sites in Libya for new wind turbine installations. This evaluation was helpful to trigger the use of large wind turbines at the selected sites along the coasts of Mediterranean.

Evaluation of physicochemical properties, skin permeation and accumulation profiles of salicylic acid amide prodrugs as sunscreen agent

Various amide prodrugs of salicylic acid were synthesised, and their physicochemical properties including lipophilicity, chemical stability and enzymatic hydrolysis were investigated. In vivo skin permeation and accumulation profiles were also evaluated using a combination of common permeation enhancing techniques such as the use of a supersaturated solution of permeants in an enhancer vehicle, a lipophilic receptor solution, removal of the stratum corneum and delipidisation of skin. Their capacity factor values were proportional to the degree of carbon–carbon saturation in the side chain. All these amides were highly stable in acetonitrile and glycerine. Amide prodrugs were converted to salicylic acid both in hairless mouse liver and skin homogenates. N-dodecyl salicylamide (C12SM) showed the lowest permeation of salicylic acid in skin compared to the other prodrugs, probably due to its low aqueous solubility. It had a high affinity for the stratum corneum and its accumulation was restricted to only the uppermost layer of skin. Thus, this amide prodrug could be a safer topical sunscreen agent with minimum potential for systemic absorption.

FAST ANALYSIS AND VALIDATION OF RUTIN IN ANTI-PSORIATIC AYURVEDIC FORMULATION BY HPLC

777 Oil is a topically applied Ayurvedic formulation used for the effective treatment of psoriasis. The formulation is composed of leaf extract of Wrightia tinctoria and Oleum Cocus nucifera. A selective, sensitive, and reproducible HPLC method was developed for analyzing marker compound of Wrightia tinctoria (Rutin) in 777 Oil for routine standardization purpose. The chromatography was performed on Phenomenex C18 (250 × 4.6 mm, 5.0 µm particle) column using methanol-water (60:40, v/v) as mobile phase; adjusted to pH 3.0 by orthophosphoric acid. The flow rate was 1.0 mL/min. with detection at 360 nm. The values of retention times and capacity factor were 3.88 and 0.40, respectively. The calibration plot showed a good linear relationship between response curve and concentration in the range of 1.0–1000.0 µgmL−1 with regression coefficient 0.9998. The detection (LOD) and quantification (LOQ) limits were found 27.0 and 95.0 ngmL−1 respectively. The statistical analysis proved that the method was precise, reproducible, selective, and accurate for the analysis of rutin in 777 Oil. The developed HPLC method is useful for the qualitative and quantitative estimation of rutin in 777 Oil and other products of traditional systems of medicine.

The role of methacrylate polymerized as porous‐layered and nanoparticle‐bound phases for open‐tubular capillary electrochromatography: Substitution of a charged monomer for a bulk monomer

The bulk monomer, butyl methacrylate (BMA), was copolymerized with an ionizable monomer (mono-(2-(methacryloyloxy)ethyl) succinate (MES)) and carbon nanotubes (CNTs) by ethylene dimethacrylate (EDMA) crosslinking to form the porous-layered and nanoparticle-bound stationary phases for open-tubular CEC. Here, two new phases were synthesized to check the role of BMA on the BMA-MES and BMA-CNT phases and the suitability of the MES monomer for concurrently acting as a bulk monomer. One phase, MES-EDMA, was simply composed of MES monomer and EDMA crosslinker and exhibited a phase construction of molecular layers, in contrast to the polymeric phases of BMA-MES. Another phase studied was MES-CNT, which SEM images showed that MES could be a good bulk monomer for a CNT-polyacrylate composite phase with embedded CNTs. For all the modified capillaries, the EOF profiles observed in phosphate buffers between pH 3.6 and 9.6 were comparable with each other and conformed to their corresponding SEM images. The residual silanols retained their influence on the EOF profiles in the MES-EDMA and BMA-MES capillaries, but diminished in the CNT-bound capillaries. In a comparison with the MES-EDMA capillary, the BMA-MES capillary afforded a stronger interaction with flavonoids and phenolic acids and still retained positive capacity factor values. Additionally, the capacity factors obtained from the BMA-CNT capillary were higher than those from the MES-CNT capillary, as the BMA-CNT phase had hydrophobic BMA units and a high surface contact area of bound CNTs.

QUANTITATIVE CORRELATIONS BETWEEN REVERSED-PHASE LC DATA AND MOLECULAR PARAMETERS FOR SOME WEAKLY RELATED PESTICIDES

Retention in reversed-phase liquid chromatography for some polar and weakly related pesticides (urea derivatives or containing the thiophosphate group), using two types of stationary phases (C8 and C18), was studied for different compositions of mobile phase in order to estimate extrapolated values of capacity factor for entirely aqueous content of mobile phase. Two organic modifiers were used in composition of mobile phase: methanol or acetonitrile. The inter-correlations between extrapolated values for the two types of stationary phase were very high. The extrapolated values for studied pesticides were correlated by linear and multilinear regressions with molecular parameters, computed by means of different theoretical approaches (PM3 quantum chemical model, and DFT computational scheme). The best correlations were obtained for extrapolated values from retention study using acetonitrile as organic modifier in mobile phase composition.

Evaluation of stationary phases and gas chromatographic detectors for determination of amines in water

For the first time, a systematic overview deals with the advantages and disadvantages of several stationary phases (polar and non-polar) and gas chromatographic detectors (flame ionization detector, nitrogen-phosphorus detector and MS) for the determination of 27 amines (aliphatic and aromatic amines and N-nitrosamines) in water samples. To increase sensitivity (250 mL of sample was eluted with 150 μL of solvent) and matrix elimination, an automatic SPE system was employed prior to GC determination. The best results in terms of resolution and retention times were achieved using a column coated with 5% phenyl-dimethylpolysiloxane (DB-5). Capacity factor (k) values for the 27 amines increased with the rise in the polarity of the stationary phase, ranging from 3.0-27.7 and 2.2-14.4 for polar (polyethylene glycol) and non-polar (DB-5) columns, respectively. The detection limits of the method were 0.9-9 μg/L for flame ionization detector, 8-95 ng/L for nitrogen-phosphorus detector and 0.2-6.3 ng/L for MS. The precision was similar for the three detectors (RSD, 3.7-6.0%). The GC-MS method was applied with a high degree of accuracy and precision to determine amines in real samples including tap, river, pond, well, swimming pool and wastewaters.

Preparation and Characterization of Inorganic Silica-Organic Polymer Mixture Based C16 Capillary Monolithic Column

Abstract A novel inorganic silica-organic polymer mixed-based capillary electrochromatography monolithic column was prepared by using precursor 3-(trimethoxysilyl) propyl methacrylate with double-functional group hydrolysis/polycondensation in acidic aqueous solution, followed by double-bond co-polymerization with organic monomer hexadecyl mathacrylate under the thermal initiated condition, and the combination of preparation of silica-based monolithic column and organic polymer monolithic column was suggested. A simple operation of controlling sol mixture using mercury infusion when the mixture infused into capillary was raised to acquire smooth interface of stationary phase. The preparation conditions of monolithic column were optimized. The structure of the monolithic columns was characterized by SEM images and nitrogen absorption method, and the results showed that the median pore diameter of the materials was in the range of 3 to 7 nm with average surface area of 103.4 M2 g−1. The influence of buffer concentration, pH value, and organic modifier content on electroosmotic flow (EOF) velocity has been investigated. Seven neutral aromatic hydrocarbons were baseline separated with column efficiency of naphthalene up to 54000 plates m−1. The reproducibility for separation time and retention factor was given in terms of RSD values at 0.9% and 0.6% (n = 5) for run-to-run injections and 1.2% and 0.8% (n = 3) for day-to-day operations. The RSD values of separation time and capacity factor of different columns (n = 3) were 8.7 and 5.7%, respectively. The studies on performance of columns indicated that the columns possess typical reverse retention mechanism.

Effects of Intra- and Interband Transitions on Electron-Phonon Coupling and Electron Heat Capacity After Short-Pulsed Laser Heating

This work considers the effects of intra- and direct interband transitions on electron heat capacity and the electron-phonon coupling factor in metals. In the event of an interband transition, the population of the electron bands around the Fermi level will change, affecting the electron density of states and subsequently the thermophysical properties. In the event of photon-induced interband transitions, this repopulation can occur even at relatively low temperatures. This introduces a photon energy-dependent population term into density of states calculations when examining the effects of direct interband transitions on electron heat capacity and the electron-phonon coupling factor in temperature regimes where traditionally only intraband transitions are considered. Example calculations are shown for copper and the two-temperature model is solved using the interband-dependent values of electron heat capacity and electron-phonon coupling factor to examine the effect of these transitions on the transient electron temperature after short-pulsed laser heating.

Electricity generation and wind potential assessment at Hurghada, Egypt

A technical and economic assessment has been made of the generation of electricity using wind turbines at one of the most promising wind sites in Egypt: Hurghada. In this paper, we used wind data recorded over 23 years for this site. The WASP program was used to calculate the values of wind speed frequency for the station, their seasonally values have been estimated and compared with measured data. Weibull parameters and the power law coefficient ( n) for all seasons at different heights (10–70 m) has been estimated and used to describe the distribution and behavior of seasonal wind speed and their frequencies at Hurghada. The monthly and annual values of wind potential at a height of 70 m were obtained by extrapolation of the 10 m data from the results of our previous article [Ahmed Shata AS, Hanitsch R. The potential of electricity generation on the east coast of Red Sea in Egypt. Renew Energy 2006;31:1597–615] using the power law. Also, the monthly plant load factor (PLF) has been estimated, which is used to determine the expected annual energy output of a wind energy conversion system (WECS). Variation of annual capacity factor with rated wind speed for 10 different wind turbines has been studied. The lower the rated speed for the WECS of the same height, the higher will be the capacity factor values. The expected electrical energy cost of kWh produced by the wind turbine ( Repower MM82) with a capacity of 2 MW considered for Hurghada station was found to be less than 1.5 € cent/kWh.

Fast screening of municipal wastewater components by reversed‐phase chromatography coupled to ultraviolet‐diode array detection

AbstractThe screening of ingredients in municipal wastewater samples was studied, by reverse‐phase high‐performance liquid chromatography (RP‐HPLC) implemented with a ultraviolet (UV)‐diode array detector, in an effort to establish a quick screening method for finding the main UV‐absorbing components of the wastewater that enters the biological treatment plant. For the purposes of direct comparison of the chromatograms obtained, a single sample taken from the inlet of municipal biological treatment plant was used for all experimental tests and the optimal elution conditions were established by detailed investigation through isocratic and gradient elution techniques. The optimal column resolution was reached by testing a broad range of capacity and selectivity factor values. The criterion used for validating the complete separation of solutes was based on the spectral purity of eluted chromatogram peaks and on the stability of retention time of a peak in real‐time chromatograms taken at different wavelengths during the elution process. From this research work, it was found that the overall chromatogram peak pattern was sensitive to the mobile phase composition and solvent system but under fixed elution conditions, the pattern of the major peaks was stable and depended on the composition of the wastewater sample. By testing different types of elution modes, it was found that the best column resolution was obtained under programmed isocratic‐gradient elution using a binary mobile phase. Finally, a relatively high column resolution method is reported for fragmentation of municipal wastewater samples.

Evaluation of the reversibility of iodide uptake by argillaceous rocks by the radial diffusion method

Laboratory radial in- and out-diffusion experiments were performed to investigate the reversibility of the iodide (I-) uptake by argillaceous rocks from the Tournemire site (France). At first, the suitability of the method was demonstrated by means of deuterium depleted water (DDW) diffusion experiments. The values for the DDW effective diffusion coefficient (1.7 to 2.7×10-11m2s-1) are indeed very close to those obtained from previous through-diffusion experiments carried out on Tournemire samples with tritiated water. The diffusion of chloride and bromide led to the determination of halide-accessible porosities, which are necessary to calculate the retardation factor (R) and the distribution ratio (RD). The calculated values for the halide-accessible porosity (2 to 5%) clearly indicated the effect of anionic exclusion and are consistent with previous data. On the contrary, the in-diffusion experiments performed with iodide clearly showed its uptake by argillite, with rock capacity factor values ranging from 14% to 25%. The corresponding values ofRD(0.035 to 0.08 L kg-1) are one order of magnitude lower than those previously derived from batch methods. At last, the experiments of iodide out-diffusion revealed that only iodide located in the halide-accessible porosity diffused out of the rock samples, suggesting that the uptake of iodide by argillite would not be reversible or that the kinetics of desorption would be low (>70 days).

Sorption, degradation and mobility of microcystins in Chinese agriculture soils: risk assessment for groundwater protection

In the present paper, sorption, persistence, and leaching behavior of three microcystin variants in Chinese agriculture soils were examined. Based on this study, the values of capacity factor and slope for three MCs variants in three soils ranged from 0.69 to 6.00, and 1.01 to 1.54, respectively. The adsorption of MCs in the soils decreased in the following order: RR>Dha 7 LR>LR. Furthermore, for each MC variant in the three soils, the adsorption rate in the soils decreased in the following order: soil A>soil C>soil B. The calculated half-time ranged between 7.9 and 17.8 days for MC-RR, 6.0–17.1 days for MC-LR, and 7.1–10.2 days for MC-Dha 7 LR. Results from leaching experiments demonstrated that recoveries of toxins in leachates ranged from 0–16.7% for RR, 73.2–88.9% for LR, and 8.9–73.1% for Dha 7 LR. The GUS value ranged from 1.48 to 2.06 for RR, 1.82–2.88 for LR, and 1.76–2.09 for Dha 7 LR. Results demonstrated the use of cyanobacterial collections as plant fertilizer is likely to be unsafe in soils.