Lower Conversion Ratio Research Articles

MODELING OF ELECTRICAL CHARACTERISTICS OF PHOTOVOLTAIC POWER SUPPLY SOURCES

The photovoltaic (PV) generators are a major element of PV power systems and they are characterized by a low conversion ratio. This accounts for the necessity to study the current-voltage and power-voltage characteristics of PV sources in order to obtain maximum power output when there are changes both in the modules themselves and in the environment where they operate. In this paper the classical and the modified single-diode models have been used to model the electrical characteristics of PV cells and modules. Mathcad software package has been used for the modeling. The impact of solar radiation, temperature and shading both on electrical characteristics and on the PV cells and modules efficiency has been studied.

Evaluation of the Energy Conversion Ratio of Vapor Explosions for the Assessment of Nuclear Reactor Safety

The calculation of energy conversion ratio of vapor explosion is an important problem for evaluating the integrity of reactor containment and pressure vessel in severe accident. The propagation and expansion stages of vapor explosion are numerically simulated based on both hydrodynamic and thermal fragmentation mechanisms. The thermal fragmentation model gives much higher pressure peak and higher energy conversion ratio than the hydrodynamic fragmentation. A low energy conversion ratio is expected in a large-scale vapor explosion because the hydrodynamic fragmentation is dominant when the pressure wave becomes strong. So the application of energy conversion ratio measured by the experiments into the assessment of reactor safety is conservative. The non-equilibrium explosion model gives the reasonable result that the vapor explosion is weak in larger vapor volume fraction conditions, which is consistent with fuel-coolant interaction experiments. The energetics of sodium vapor explosion is also examined. The high saturation temperature of sodium results in a much lower pressure peak. A coolable fuel debris bed can be formed during the core disruptive accident.

Phytoplankton blooms and fish recruitment rate: effects of spatial distribution

We consider the spatio-temporal dynamics of a spatially-structured generalization of the phytoplankton-zooplankton-fish larvae model system proposed earlier (Biktashev et al., 2003, J. Plankton Res. 5, 21–33; James et al., 2003, Ecol. Model. 160, 77–90). In contrast to Pitchford and Brindley (2001, Bull. Math. Biol. 63, 527–546), who were concerned with small scale patchiness (i.e., 1–10 m), on which the (stochastic) raptorial behaviour of individual larvae is important, we address here the much larger scale ‘patchy’ problems (i.e., 10–100 km), on which both larvae and plankton may be regarded as passive tracers of the fluid motion, dispersed and mixed by the turbulent diffusion processes. In particular, we study the dependence of the fish recruitment on carrying capacities of the plankton subsystem and on spatio-temporal evolution of that subsystem with respect to the larvae hatching site(s). It is shown that the main features found both in the nonstructured and age-structured spatially uniform models are observed in the spatially structured case, but that spatial effects can significantly modify the overall quantitative outcome. Spatial patterns in the metamorphosed fish distribution are a consequence of quasi-local interaction of larvae with plankton, in which the dispersion of larvae by large scale turbulent eddies plays little part due to the relatively short timescale of the larvae development. As a result, in a strong phyto/zooplankton subsystem, with fast reproduction rate and large carrying capacity of phytoplankton and high conversion ratio of zooplankton, recruitment success depends only on the localization and timing of the hatching with respect to the plankton patches. In a weak phyto/zooplankton system, with slow reproduction rate and small carrying capacity of phytoplankton and low conversion ratio of zooplankton, the larvae may significantly influence the evolution of the plankton patches, which may lead to nontrivial cooperative effects between different patches of larvae. However, in this case, recruitment is very low.

An empirical investigation of Web site characteristics, consumer emotional states and on-line shopping behaviors

On-line retailing is rapidly emerging as an alternative mode of shopping and is expected to garner a substantial share of the retail market in future. The low order conversion ratio of Web site visitors and the inability of on-line retailers to attract repeat customers are the main hurdles identified for their lack of success at present. Enhancement of Web site features that facilitate the navigation of the consumer through the purchasing stages is suggested as a means of overcoming these hurdles. The present study proposes the stimulus–organism–response (S-O-R) framework of Mehrabian and Russell [Mehrabian A, Russell JA. An approach to environmental psychology. Cambridge (MA): MIT Press, 1974] as a viable model for the investigation of consumer responses to the Web sites of virtual stores and finds substantial support for its propositions. The paper concludes by offering some directions for Web site design as well as further research in this area.

Serum neuropeptide Y (NPY) and leptin concentrations in pigs selected for components of efficient lean growth

Responses in log transformed serum neuropeptide Y (NPY) concentration and leptin concentration after six generations of divergent selection on components of efficient lean growth in pigs were measured. From an animal breeding perspective, serum NPY and/or leptin concentrations could be used as physiological predictors of genetic merit if there were significant responses to selection. At 90 kg liveweight, log transformed serum NPY concentrations were increased with divergent selection for low food conversion ratio (LFC) (6.31 versus 5.72, SED 0.09 log(pmol/L)) or for high lean growth rate (LGA) (5.80 versus 5.37 log(pmol/L)) but not with selection on daily food intake (DFI) (6.26 versus 6.14 log(pmol/L)). Selection for high DFI was associated with increased serum leptin concentration (3.06 versus 2.45, SED 0.21 ng/mL human equivalent (HE)) as was selection for low LFC (3.04 versus 2.46 ng/mL HE). Correlations between leptin and predicted lipid weight increased with stage of test (0.13, 0.34 and 0.43, SE 0.08 at 30, 50 and 75 kg). The high correlations between successive serum NPY concentrations (0.80, SE 0.11) suggest that changes in body composition with time would not be reflected in serum NPY concentrations. Serum NPY and, to a lesser extent, serum leptin concentrations were insensitive to dietary differences in total lysine: energy and indicated that studies using a genetic resource population of animals may be more powerful than nutritional studies using isoenergetic diets differing in lysine content to examine aspects of function of serum concentrations of NPY and leptin in pigs.

Drastic SOx Removal and Influences of Various Factors in O2/CO2 Pulverized Coal Combustion System

Coal combustion with O2/CO2 is promising because of its easy CO2 recovery, extremely low NOx emission, and high desulfurization efficiency. However, there exist many unknowns concerning in-furnace desulfurization in O2/CO2 pulverized coal combustion, which is much different from that in conventional coal combustion. Research on CaSO4 decomposition aimed at desulfurization in O2/CO2 pulverized coal combustion is also necessary to investigate the desulfurization behaviors. The kinetics of desulfurization and CaSO4 decomposition were examined in atmospheres of high CO2 and SO2 concentrations. The characteristics and mechanisms of desulfurization in an O2/CO2 pulverized coal combustion system were clarified by combining experimental results and modeling with the kinetics obtained by us. The effects of sorbent type, residence time, and so on were investigated. It has been identified that the system desulfurization efficiency in O2/CO2 pulverized coal combustion is increased to about four to six times as high as that of conventional pulverized coal combustion mainly attributed to the following: (1) practical residence time of SO2 is extended and SO2 is enriched inside furnace owing to flue gas recirculation; (2) CaSO4 decomposition is inhibited because of a high SO2 concentration. Their contributions were quantitatively clarified as follows: below 1450 K, the former contributes above two-thirds, whereas above 1500 K, the latter contributes above two-thirds to the overall increase in desulfurization efficiency. The system desulfurization efficiency in O2/CO2 pulverized coal combustion maintains a high value in a wide range of temperature and particle residence time. These results of a high system desulfurization efficiency, in addition to an extremely low conversion ratio from fuel-N to exhausted NO and an easy CO2 recovery without CO2 separation process, make simultaneous control of CO2/NOx/SOx possible in O2/CO2 pulverized coal combustion. It can be concluded that O2/CO2 pulverized coal combustion is a promising advanced coal combustion technology for the protection of global environment.

生物学的排水処理における硝化活性およびＮ２Ｏ生成速度に及ぼす水温および窒素負荷の影響

Activated sludge processes coupled with membrane filters were operated at 10, 20 and 30°C to study the influences of the water temperature, and various kinds of the nitrogen load conditions on nitrification and emission of N2O, known as the greenhouse gas. The results obtained were as follows: Lower temperature, higher nitrogen concentration in the influent and shorter HRT caused the decrease of the nitrification efficiency and the increase of N2O conversion ratio. In addition, the effects of the nitrogen load was higher at low water temperature than high temperature. Under the same condition of the nitrogen load per MLSS, the runs with low MLSS concentration achieved high nitrification rate and low N2O conversion ratio than those with high MLSS concentration. It was suggested that oxygen diffusion was insufficient in the runs with higher MLSS concentration because of the larger-sized flocculation of the microorganisms, and so that effective oxygen supply was very important to improve the nitrification efficiency under such operational condition.

Performance and physiological variables in broiler chicken lines differing in susceptibility to the ascites syndrome: 1. Changes in blood gases as a function of ambient temperature

1. Male broilers of 5 genetic stocks (A, B, C, D, E) selected in different ways for fast growth and low food conversion ratio (FCR) and differing in ascites sensitivity were subjected to 2 different ambient temperature step down regimens: high temperature (HT: 33 to 20degreeC over 33 d) and low temperature (LT: 30 to 15degreeC over 17 d). 2. Ascites incidence was recorded daily. Food intake and body weight gain were measured weekly and FCR was calculated. Heat production (Hp) was calculated using the comparative slaughter method. At 28 d venous samples were taken for blood gas analysis and haematocrit and relative heart, lung and liver weights were recorded. 3. Populations A and C showed the highest growth rates combined with a low FCR and a higher ascites incidence. A low FCR in these stocks was attributable to low values for Hp. These stocks also had low pO2 and high pCO2 in venous blood at low ambient temperature compared with other stocks. Stock B, which exhibited the slowest growth rate and the highest FCR, was not susceptible to ascites and showed higher Hp and pO2 and pCO2 at low ambient temperature. Populations D and E were intermediate for almost all variables. Heart and lung weights were both increased at LT , while liver weight did not differ between temperature regimes. 4. Our results show that a high haematocrit is not necessarily linked with an increased susceptibility to ascites.

Food Efficiency in Pure Strains and Hybrids of Laying Hens Analysed in a Diallel Cross: I. Effect of Total Heterosis on Important Traits

Abstract The present paper describes the effect of heterosis found in a full diallel design 4×4 pure strains of laying hens. There were 36 individually measured hens per combination. In economic terms and with regard to a low food conversion ratio (FCR), positive heterosis was found for egg weight, egg number and total egg mass, while negative heterosis was found for food consumption in the rearing period 0-16 weeks, body weight, weight gain and yolk percentage. On average, there was negative but non-significant heterosis for FCR. Five of the combinations had positive but non-significant heterosis in FCR, while seven combinations had negative heterosis; three were significantly different from zero. No significant differences in mortality between the pure strains and the hybrids were found.

Effects of feeding tryptophan-limiting diets on the conversion ratio of tryptophan to niacin in rats.

We investigated the effects of feeding various types of nicotinic acid-free, tryptophan-limiting diets on the conversion ratio of tryptophan to niacin in rats. Various tryptophan-limiting diets were made by adding zein, gelatin, glycine, threonine, methionine, or glycine + threonine + methionine to a nicotinic acid-free, 9% casein diet. When the rats were fed with the tryptophan-limiting diets, the conversion ratio of tryptophan to niacin was markedly decreased. However, the ratio recovered after the addition of tryptophan to the tryptophan-limiting diets. These results clearly prove that the conversion was lowest when the rats were fed with the tryptophan-limiting diets. Therefore, we think that the pellagragenic factor of corn is simply due to a low content of tryptophan, but the adverse effect is due to a low conversion ratio of tryptophan to niacin.

The information content of a convertible debt offer announcement

We develop a model of convertible debt financing that combines issue and call decisions into a common framework. The model suggests a role for refinancing costs in a manager's efforts to signal firm productivity to investors by an appropriate choice of debt issue terms. A cross section of convertible debt offers can be divided into two groups: a high conversion ratio group and a low conversion ratio group. The model predicts that high conversion ratios are negatively correlated with offer announcement stock returns and low conversion ratios are uncorrelated with offer announcement stock returns. The model is tested on a sample of 124 convertible debt offer announcements. Test results support model accuracy.

NO-CO Activity and Selectivity over a Pt10Rh90(111) Alloy Catalyst in the 10-Torr Pressure Range

We have studied the effects of temperature, NO conversion, and NO-CO ratio on the activity and selectivity of the NO-CO reaction over a Pt10Rh90(111) surface. The NO-CO activity over the Pt10Rh90(111) is very similar to that over the Rh(111) surface from 573 to 648 K in that both surfaces have the same Ea, reaction orders, products, and selectivities. The turnover numbers for the Pt10Rh90(111) alloy are slightly lower than those for Rh(111), when compared on a per surface atom basis; however, the rates per surface Rh atom are virtually unchanged. This behavior suggests that the primary effect of Pt is to dilute the Rh surface atom concentration; however, it is equally consistent with electronic modification of all surface atoms. The surface composition remains essentially unchanged over the range of reaction conditions that we explored; however, we did not go extremely oxidizing, which is the condition known to have the largest effect on the surface composition. The Pt10Rh90(111) single crystal mimics the behavior of supported Pt-Rh catalysts in that both show high (∼ 75%) selectivity for N2O at low temperature, low conversion, or high NO-CO ratio and low or zero N2O production at high temperature and high NO conversion. Our conclusion is that the N2O selectivity and the overall reaction rate are controlled by the NO adsorption/desorption equilibrium. Adsorbed NO strongly inhibits the NO dissociation reaction, keeping surface N coverages low. However, once the temperature is raised or the NO pressure lowered, surface NO coverages fall, accelerating the NO dissociation reaction and likewise increasing the N + N reaction. We conclude that these surface kinetics explain the curious N2O selectivities observed during light-off of supported catalysts.

Growth Assessment of Some Ornamental Fish Species Fed with Low Cost Feeds

Three feeds were formulated using low cost raw materials with proteincontents ranging from 44% - 62% and prepared in the laboratory and weretested against an imported feed (protein 32%) on young stages (initial weight,0.03 - 0.71 g.) of four species of ornamental fish namely, Rosy Barb (Barbasconchoniusy, Angel (Pterophyllum scalurey; Gold fish (Carassius auratus auratus)and Goggle - eye iCarassius sp.) over a period of 2 months to assess thefeasibility of using locally prepared feeds in rearing of very young stages inornamental fish culture. High Assimilation Efficiencies (56 - 82 ~~), low Food Conversion Ratios(less thae 2), high Growth Rates (0.005) - 0.02 g. day) and high SurvivalRates (93% - 100) shown by all species on the prepared diets proved thelocally prepared feeds to be highly acceptable. The results also reveal that there is an optimal level of dietary proteinrequirement in the range of 44 - 50% for three of the four species studied. The study also showed that the cost of feeds can be reduced by (a) using low cost protein sources such as shrimp heads, fish/meatoffals, rice bran and soya flour; (b) using more carbohydrates with less protein.

An action function approach to network dynamics and the meaning of representations: [formula omitted]. Faculty of Medicine, Medical Sciences Building, Room 7313, University of Toronto, Toronto, Ontario, Canada M5S 1A8

The hydriodic acid decomposition section (HIx section) of the iodine–sulfur water splitting hydrogen production process (I–S process), to a large extent, determines the efficiency of the whole process. The flowsheet of the HIx section includes several internal circuits, which can recover the lost HI due to the distillation of the azeotrope and the low one-pass conversion ratio of the HI decompostion reaction. The employment of the circuits is capable of increasing the utilization of the input HI. However, different designs of the circuits influence the mass and heat balance of the flowsheet, and furthermore result in distinctions of the hydrogen production efficiency and the required input rate. In order to examine the performance of the HIx section flowsheets with diverse internal circuits and pursue high efficiency, the present research used simulation methods to invesigate the HIx section flowsheet. The effects of different designs of internal circuits in the HIx section on the required input flow rate and heat duty for producing 1 mol hydrogen were studied. Based on the results, the most efficient circuit design was proposed and compared with the work of other researchers. In addition, the heat recovery problems of the flowsheet were discussed.

Metabolism of prostaglandin D2 in isolated rat lung: the stereospecific formation of 9α, 11β-prostaglandin F2 from prostaglandin D2

The metabolic transformation of exogenous prostaglandin D2 was investigated in isolated perfused rat lung. Dose-dependent formation (2-150 ng) of 9 alpha,11 beta-prostaglandin F2, corresponding to about 0.1% of the perfused dose of prostaglandin D2, was observed by specific radioimmunoassay both in the perfusate and in lung tissue after a 5-min perfusion. To investigate the reason for this low conversion ratio, we analyzed the metabolites of tritium-labeled 9 alpha,11 beta-prostaglandin F2 and prostaglandin D2 by boric acid-impregnated TLC and HPLC. By 5 min after the start of perfusion, 9 alpha,11 beta-prostaglandin F2 disappeared completely from the perfusate and the major product formed remained unchanged during the remainder of the 30-min perfusion. The major product was separated by TLC and identified as 13,14-dihydro-15-keto-9 alpha,11 beta-prostaglandin F2 by GC/MS. In contrast, pulmonary breakdown of prostaglandin D2 was slow and two major metabolites in the perfusate increased with time, each representing 56% and 11% of the total radioactivity at the end of the perfusion. The major product (56%) was identified as 13,14-dihydro-15-ketoprostaglandin D2 and the minor one (11%) was tentatively identified as 13,14-dihydro-15-keto-9 alpha,11 beta-prostaglandin F2 based on the results from radioimmunoassays, TLC, HPLC, and the time course of pulmonary breakdown. These results demonstrate that the metabolism of prostaglandin D2 in rat lung involves at least two pathways, one by 15-hydroxyprostaglandin dehydrogenase and the other by 11-ketoreductase, and that the 9 alpha,11 beta-prostaglandin F2 formed is rapidly metabolized to 13,14-dihydro-15-keto-9 alpha,11 beta-prostaglandin F2.

Intensive polyculture of common carp ( Cyprinus carpio L.) and herbivorous fish [silver carp, Hypophthalmichthys molitrix (Val.), and grass carp, Ctenopharyngodon idella (Val.)

Intensive polyculture of common carp and herbivorous fish (silver carp and grass carp) at high stocking densities and with intensive feeding with fodder and mineral and organic fertilization was carried out without mechanized aeration and automated feeding. Two stocking patterns were tested. The first, in Pond 1 (with an area of 2.5 ha), had the following stocking rates: one-year carp (C 1), 8000 fish/ha; one-year silver carp (S 1), 1500 fish/ha; and one-year grass carp (G 1), 200 fish/ha. The yield was 6292 kg/ha of standard consumer fish (C 1+ 743 g, S 1+ 944 g, and G 1+ 1000 g) at a relatively low food conversion ratio (2.24) and high survival of all fish. Within the total yield, the two-year carp contributed 76%, the silver carp 21%, and the grass carp 3%. The second stocking pattern, in Pond 2 (0.25 ha), had the following rates: C 1, 8500 fish/ha; S 1, 2000 fish/ha; and G 1, 200 fish/ha, and produced a still higher total yield (6629 kg/ha) at a relatively low food conversion ratio (2.10). The two-year carp in Pond 2 contributed 88% of the total yield, and the herbivorous fish only 12% even though they accounted for 20% of the stock. Our results (Pond 2) are compared with other record yield experiments under similar conditions but including tilapia. At a total stocking rate of 10 700 fish/ha and without participation of tilapia, over a period of 186 days (as against 126 days in the other experiment), our experiments gave a total yield which was 347 kg/ha higher at a food coefficient 15% lower. The growth period was 60 days longer in our experiments but it included April and October when water temperature is much below the optimum and only 4% of the total amount of fodder was assimilated.

Preliminary investigations on the suitability of ground water for aquaculture in Saudi Arabia

Ground water sampled at five sites in the Al-Quasim region of Saudi Arabia was found to be suitable for the culture of Tilapia nilotica in terms of pH, alkalinity, salinity and nitrite-nitrogen. Four of the five sites had very hard water (390–1000 mg/l). Fish growth was low and feed conversion ratios high in preliminary production trials.

Biotransformation of 3-Methyl-2-buten-1-ol and 3-Methyl-3-buten-1-ol by the Suspension Cultures of Glycine max

The biotransformation of 3-methyl-2-buten-1-ol and 3-methyl-3-buten-1-ol by the suspension cultures of Glycinc max (soy bean) under various conditions has been investigated. 3-Methyl-2-buten-1-ol was biotransformed into 3-methyl-2-butenal by the cultures at a high conversion ratio, but not into 3-methyl-3-buten-1-ol, while 3-methyl-3-buten-1-ol was biotransformed, although at a low conversion ratio, into 3-methyl-2-buten-1-ol and 3-methyl-2-butenal. More than 99% of the substances detected by GLC were found in the medium, and only a trace amount was found in the callus. The effects of auxins, light, shaking, and the amount of callus inoculum have been investigated. Throughout these experiments, no monoterpene formation was observed.

The relative protein and energy requirements of boars, gilts and barrows

Two experiments were conducted to study the response of boars, gilts and barrows to increasing levels of dietary crude protein and digestible energy. In the first experiment boars, gilts and barrows were fed diets ranging in crude protein from 14.6 to 22.7 per cent in restrictive amounts between 20 and 70 kg liveweight. Growth rate and food conversion efficiency measurements ranked the sexes in order of superiority as boars, gilts and barrows. Boars contained more lean in their hams than gilts or barrows and had lower back fat measurements than barrows. Although analysis of variance indicated there was no significant sex by protein interaction, the multiple regression equations of growth rate and the proportion of lean in the ham for the three sexes were significantly different from one another. The response curves based on the regression equations indicated that for optimum growth, boars and gilts required 19.6 per cent crude protein whereas barrows required only 18.4 per cent crude protein. The proportion of lean in the ham was maximized with 21 per cent crude protein for boars and 20 per cent crude protein for the gilts and barrows. There was a significant quadratic relationship between economic returns and dietary protein. The relationship was the same for boars and gilts and significantly different from that for barrows; returns were maximized at approximately the same protein level as growth rate for the three sexes. In the second experiment, 30 boars and 30 gilts were allocated to 30 treatment groups involving the two sexes, three levels of digestible energy (14.59, 15.51 and 16.22 MJ kg-1) and five levels of crude protein (18.2, 19.4, 20.6, 21.8 and 23.0 per cent). All diets were fed restrictively and pig performance was compared over the liveweight range 20 to 80 kg. Boars grew significantly faster, had a significantly lower food conversion ratio and produced leaner carcases than gilts. Increasing the DE level of the diet improved growth rate and food conversion efficiency but reduced carcase quality. Dietary protein level had no effect on any performance or carcase quality measurement.

Initial mechanisms involved in substituted magnetite oxidation

The oxidation kinetics of slightly-substituted and pure magnetites, at low conversion ratio is controlled, both by diffusion and surface reaction. However, for highly-subtituted magnetites, diffusion is the sole regulating process. The results are related to the semiconducting properties of the compounds.