Operational characteristics of a 1.2-MW biomass gasification and power generation plant

In this study, we analyzed the operational characteristics of a 1.2-MW rice husk gasification and power generation plant located in Changxing, Zhejiang province, China. The influences of gasification temperature, equivalence ratio (ER), feeding rate and rice husk water content on the gasification characteristics in a fluidized bed gasifier were investigated. The axial temperature profile in the dense phase of the gasifier showed that inadequate fluidization occurred inside the bed, and that the temperature was closely related to changes in ER and feeding rate. The bed temperature increased linearly with increasing ER when the feeding rate was kept constant, while a higher feeding rate corresponded to a lower bed temperature at fixed ER. The gas heating value decreased with increasing temperature, while the feeding rate had little effect. When the gasification temperature was 700-800C, the gas heating value ranged from 5450-6400kJ/Nm3. The water content of the rice husk had an obvious influence on the operation of the gasifier: increases in water content up to 15% resulted in increasing ER and gas yield, while water contents above 15% caused aberrant temperature fluctuations. The problems in this plant are discussed in the light of operational experience of MW-scale biomass gasification and power generation plants.

Chemisorption and reaction characteristics of methyl radicals on Cu(110)

Methyl radicals are generated by pyrolysis of azomethane, and the condition for achieving neat adsorption on Cu(110) is described for studying their chemisorption and reaction characteristics. The radical-surface system is examined by X-ray photoemission spectroscopy, ultraviolet photoemission spectroscopy, temperature-programmed desorption, low-energy electron diffraction (LEED), and high-resolution electron energy loss spectroscopy under ultrahigh vacuum conditions. It is observed that a small fraction of impinging CH3 radicals decompose into methylene possibly on surface defect sites. This type of CH2 radical has no apparent effect on CH3(ads) surface chemistry initiated by dehydrogenation to form active CH2(ads) followed by chain reactions to yield high-mass alkyl products. All thermal desorption products, such as H-2, CH4, C2H4, C2H6, and C3H6, are detected with a single desorption peak near 475 K. The product yields increase with surface coverage until saturation corresponding to 0.50 monolayer of CH3(ads). The mass distribution is, however, invariant with initial CH3(ads) coverage, and all desorbed species exhibit first-order reaction kinetics. LEED measurement reveals a c(2 x 2) adsorbate structure independent of the amount of gaseous exposure. This strongly suggests that the radicals aggregate into close-packed two-dimensional islands at any exposure. The islanding behavior can be correlated with the reaction kinetics and is deemed to be essential for the chain propagation reactions. Some relevant aspects of the CH3/Cu(111) system are also presented. The new results are compared with those of prior studies employing methyl halides as radical sources. Major differences are found in the product distribution and desorption kinetics, and these are attributed to the influence of surface halogen atoms present in those earlier investigations.

Investigations of the characteristics and mode of action of an algalytic bacterium isolated from Tai Lake

An algalytic bacterium provisionally designated as TL1 was isolated from Tai Lake, a large freshwater lake in the Yangtze Delta plain on the border of the Jiangsu and Zhejiang provinces and close to Wuxi city in the People's Republic of China. Strain TL1 was identified as Achromobacter sp. based on its biophysical and biochemical properties and the analysis of its 16S rRNA sequence. Microcystis aeruginosa, which is the most common toxic cyanobacterium in eutrophic freshwater, could be decomposed by strain TL1. The results showed that after inoculation with the algalytic bacterium, the content of chlorophyll-a, maximum PSII quantum yield, and maximum electron transport rates of the alga decreased sharply. At first, the algal cells enhanced the activities of some antioxidative enzymes, but subsequently, the activities of antioxidative enzymes fell sharply once damage of the algal cells was achieved. The filtrate from strain TL1 culture suspension, after autoclaving and treatments with proteinase K, strongly inhibited algal growth, indicating that the lytic metabolites were extracellular and thermostable, not a protein.

Shear effects on the properties and separation characteristics of whey protein precipitates

Selective isoelectric whey protein precipitation and aggregation is carried out at laboratory scale in a standard configuration batch agitation vessel. Geometric scale-up of this operation is implemented on the basis of constant impeller power input per unit volume and subsequent clarification is achieved by high speed disc-stack centrifugation. Particle size and fractal geometry are important in achieving efficient separation while aggregates need to be strong enough to resist the more extreme levels of shear that are encountered during processing, for example through pumps, valves and at the centrifuge inlet zone. This study investigates how impeller agitation intensity and ageing time affect aggregate size, strength, fractal dimension and hindered settling rate at laboratory scale in order to determine conditions conducive for improved separation. Particle strength is measured by observing the effects of subjecting aggregates to moderate and high levels of process shear in a capillary rig and through a partially open ball-valve respectively. The protein precipitate yield is also investigated with respect to ageing time and impeller agitation intensity. A pilot scale study is undertaken to investigate scale-up and how agitation vessel shear affects centrifugal separation efficiency. Laboratory scale studies show that precipitates subject to higher impeller shear-rates during the addition of the precipitation agent are smaller but more compact than those subject to lower impeller agitation and are better able to resist turbulent breakage. They are thus more likely to provide a better feed for more efficient centrifugal separation. Protein precipitation yield improves significantly with ageing, and 50 minutes of ageing is required to obtain a 70 - 80% yield of α-lactalbumin. Geometric scale-up of the agitation vessel at constant power per unit volume results in aggregates of broadly similar size exhibiting similar trends but with some differences due to the absence of dynamic similarity due to longer circulation time and higher tip speed in the larger vessel. Disc stack centrifuge clarification efficiency curves show aggregates formed at higher shear-rates separate more efficiently, in accordance with laboratory scale projections. Exposure of aggregates to highly turbulent conditions, even for short exposure times, can lead to a large reduction in particle size. Thus, improving separation efficiencies can be achieved by the identification of high shear zones in a centrifugal process and the subsequent elimination or amelioration of such.

The effect of anisotropic elasticity on the yielding characteristics of overconsolidated natural clay

Quantitative application of elastoplastic theory to the yielding behaviour of natural soils has always been uncertain. Part of the reason is that the theory was developed for reconstituted materials with isotropic structure, in contrast to natural soils that are usually anisotropic. The approach considered in this study assumes that pre-yielding behaviour is governed by the theory of linear anisotropic elasticity and that yield loci in the mean effective stress ( p') – deviator stress (q) plane are aligned approximately along the coefficient of earth pressure (K0) line. The assumption of a rotated yield locus associated with anisotropic elastic behaviour within the state boundary surface indicates that the elastic wall within the state boundary surface is inclined. The form of the state boundary surface has been determined mathematically in terms of anisotropic elastic and Cam-Clay soil parameters. Stress path tests were conducted on samples of Belfast Upper Boulder Clay removed from a depth of 28 m below ground surface. Good agreement was found between predicted and measured yield loci. The study also examined the influence of subsequent isotropic compression on the yielding characteristics of the natural clay. The indications are that the anisotropy developed during deposition disappears when the sample is loaded to a stress level at least twice the stress generated during the original deposition process. The methods developed in the paper have also been applied to test results reported previously on Winnipeg clay, and good agreement was obtained.

Effects of particle plasticity characteristics on local interface stress in particle reinforced composite during uniaxial tension

For elastoplastic particle reinforced metal matrix composites, failure may originate from interface debonding between the particles and the matrix, both elastoplastic and matrix fracture near the interface. To calculate the stress and strain distribution in these regions, a single reinforcing particle axisymmetric unit cell model is used in this article. The nodes at the interface of the particle and the matrix are tied. The development of interfacial decohesion is not modelled. Finite element modelling is used, to reveal the effects of particle strain hardening rate, yield stress and elastic modulus on the interfacial traction vector (or stress vector), interface deformation and the stress distribution within the unit cell, when the composite is under uniaxial tension. The results show that the stress distribution and the interface deformation are sensitive to the strain hardening rate and the yield stress of the particle. With increasing particle strain hardening rate and yield stress, the interfacial traction vector and internal stress distribution vary in larger ranges, the maximum interfacial traction vector and the maximum internal stress both increase, while the interface deformation decreases. In contrast, the particle elastic modulus has little effect on the interfacial traction vector, internal stress and interface deformation.

Investigation Into The Effect of Varying L-leucine Concentration on the product characteristics of Spray-dried Liposome Powders

Spray-dried formulations offer an attractive delivery system for administration of drug encapsulated into liposomes to the lung, but can suffer from low encapsulation efficiency and poor aerodynamic properties. In this paper the effect of the concentration of the anti-adherent l-leucine was investigated in tandem with the protectants sucrose and trehalose. Two manufacturing methods were compared in terms of their ability to offer small liposomal size, low polydispersity and high encapsulation of the drug indometacin. Unexpectedly sucrose offered the best protection to the liposomes during the spray drying process, although formulations containing trehalose formed products with the best powder characteristics for pulmonary delivery; high glass transition values, fine powder fraction and yield. It was also found that l-leucine contributed positively to the characteristics of the powders, but that it should be used with care as above the optimum concentration of 0.5% (w/w) the size and polydispersity index increased significantly for both disaccharide formulations. The method of liposome preparation had no effect on the stability or encapsulation efficiency of spray-dried powders containing optimal protectant and anti-adherent. Using l-leucine at concentrations higher than the optimum level caused instability in the reconstituted liposomes.

Hydrolysis characteristics and kinetics of waste hay biomass as a potential energy crop for fermentable sugars production using autoclave parr reactor system

The use of the organic fraction of municipal solid waste crops has received considerable attention as a sustainable feedstock that can replace fossil fuels for the production of renewable energy. Therefore, municipal bin-waste in the form of hay was investigated as a potential energy crop for fermentable sugars production. Hydrolysis of hay by dilute phosphoric acid was carried out in autoclave parr reactor, where reactor temperature (135-200 degrees c) and acid concentration (2.5-10% (w/w)) were examined. Analysis of the decomposition rate of hemicellulosic biomass was undertaken using HPLC of the reaction products. Xylose production reached a maximum value of 13.5 g/100 g dry mass corresponding to a yield of 67% at the best identified conditions of 2.5 wt% H3PO4, 175 degrees C, 10 min reaction time, and at 5 wt% H3PO4, 150 degrees C, and 5 min reaction time. For glucose, an average yield of 25% was obtained at 5 wt% H3PO4, 175 degrees C and 30 min. Glucose degradation to HMF was achieved at 10 wt% H3PO4 and 200 degrees C. The maximum yield for produced arabinose was an average of 3 g/100 g dry. mass corresponding to 100% of the total possible arabinose. The kinetic study of the acid hydrolysis was also carried out using the Saeman and the Two-fraction models. It was found for both models that the kinetic constants (k) depend on the acid concentration and temperature. For xylose and arabinose it was found that the rate of formation was more favoured than the rate of degradation. By contrast, for glucose it was found that glucose degradation was occurring faster than glucose formation. It can be concluded that dilute phosphoric acid hydrolysis of hay crop is feasible for the production of fermentable sugars which are essential for bioethanol synthesis. 

Effects of sintering temperature on morphology and mechanical characteristics of 3D printed porous titanium used as dental implant

Porous titanium samples were manufactured using the 3D printing and sintering method in order to determine the effects of final sintering temperature on morphology and mechanical properties. Cylindrical samples were printed and split into groups according to a final sintering temperature (FST). Irregular geometry samples were also printed and split into groups according to their FST. The cylindrical samples were used to determine part shrinkage, in compressive tests to provide stress-strain data, in microCT scans to provide internal morphology data and for optical microscopy to determine surface morphology. All of the samples were used in microhardness testing to establish the hardness. Below 1100 C FST, shrinkage was in the region of 20% but increased to approximately 30% by a FST of 1300 C. Porosity varied from a maximum of approximately 65% at the surface to the region of 30% internally. Between 97 and 99% of the internal porosity is interconnected. Average pore size varied between 24 µm at the surface and 19 µm internally. Sample hardness increased to in excess of 300 HV0.05 with increasing FST while samples with an FST of below 1250 C produced an elastic-brittle stress/strain curve and samples above this displayed elastic-plastic behaviour. Yield strength increased significantly through the range of sintering temperatures while the Young's modulus remained fairly consistent. © 2013 Elsevier B.V.

Characteristics of the complex received signal in dynamic body area networks

This paper investigates the characteristics of the complex received signal in body area networks for two environments at the opposite ends of the multipath spectrum at 2.45 GHz. Important attributes of the complex channel such as the Gaussianity of the quadrature components and power imbalance, which form the basis of many popular fading models, are investigated. It is found that in anechoic environments the assumption of Gaussian distributed quadrature components will not always yield a satisfactory fit. Using a complex received signal model which considers a non-isotropic scattered signal contribution along with the presence of an optional dominant signal component, we use an autocorrelation function originally derived for mobile-to-mobile communications to model the temporal behavior of a range of dynamic body area network channels with considerable success. In reverberant environments, it was observed that the real part of the complex autocorrelation function for body area network channels decayed slightly quicker than that expected in traditional land mobile channels. © 2013 IEEE.

Competing demands for a complex system : photosystem II repair, photoprotection and quantum yield

Photosynthesis in general is a key biological process on Earth and Photo system II (PSII) is an important component of this process. PSII is the only enzyme capable of oxidizing water and is largely responsible for the primordial build-up and present maintenance of the oxygen in the atmosphere. This thesis endeavoured to understand the link between structure and function in PSII with special focus on primary photochemistry, repair/photodamage and spectral characteristics. The deletion of the PsbU subunit ofPSII in cyanobacteria caused a decoupling of the Phycobilisomes (PBS) from PSII, likely as a result of increased rates of PSII photodamage with the PBS decoupling acting as a measure to protect PSII from further damage. Isolated fractions of spinach thylakoid membranes were utilized to characterize the heterogeneity present in the various compartments of the thylakoid membrane. It was found that the pooled PSIILHCII pigment populations were connected in the grana stack and there was also a progressive decrease in the reaction rates of primary photochemistry and antennae size of PSII as the sample origin moved from grana to stroma. The results were consistent with PSII complexes becoming damaged in the grana and being sent to the stroma for repair. The dramatic quenching of variable fluorescence and overall fluorescent yield of PSII in desiccated lichens was also studied in order to investigate the mechanism by which the quenching operated. It was determined that the source of the quenching was a novel long wavelength emitting external quencher. Point mutations to amino acids acting as ligands to chromophores of interest in PSII were utilized in cyanobacteria to determine the role of specific chromophores in energy transfer and primary photochemistry. These results indicated that the Hl14 ligated chlorophyll acts as the 'trap' chlorophyll in CP47 at low temperature and that the Q130E mutation imparts considerable changes to PSII electron transfer kinetics, essentially protecting the complex via increased non-radiative charge Photosynthesis in general is a key biological process on Earth and Photo system II (PSII) is an important component of this process. PSII is the only enzyme capable of oxidizing water and is largely responsible for the primordial build-up and present maintenance of the oxygen in the atmosphere. This thesis endeavoured to understand the link between structure and function in PSII with special focus on primary photochemistry, repair/photodamage and spectral characteristics. The deletion of the PsbU subunit ofPSII in cyanobacteria caused a decoupling of the Phycobilisomes (PBS) from PSII, likely as a result of increased rates of PSII photodamage with the PBS decoupling acting as a measure to protect PSII from further damage. Isolated fractions of spinach thylakoid membranes were utilized to characterize the heterogeneity present in the various compartments of the thylakoid membrane. It was found that the pooled PSIILHCII pigment populations were connected in the grana stack and there was also a progressive decrease in the reaction rates of primary photochemistry and antennae size of PSII as the sample origin moved from grana to stroma. The results were consistent with PSII complexes becoming damaged in the grana and being sent to the stroma for repair. The dramatic quenching of variable fluorescence and overall fluorescent yield of PSII in desiccated lichens was also studied in order to investigate the mechanism by which the quenching operated. It was determined that the source of the quenching was a novel long wavelength emitting external quencher. Point mutations to amino acids acting as ligands to chromophores of interest in PSII were utilized in cyanobacteria to determine the role of specific chromophores in energy transfer and primary photochemistry. These results indicated that the Hl14 ligated chlorophyll acts as the 'trap' chlorophyll in CP47 at low temperature and that the Q130E mutation imparts considerable changes to PSII electron transfer kinetics, essentially protecting the complex via increased non-radiative charge.

Population Characteristics of Prawns in Natural and Selective Stocking System

present work deals with the various aspects of population characteristics of penaeus indicus ,Metapenaeus dobsoni and metapenaeus monoceros during their nursery phase in tidal ponds and adjacent backwaters.Importance of the present study is to suggest scientific basis for the management of penaeid resources in tidal ponds and backwaters based on their biological characteristics to ensure better yield.Seasonal closure of fishing will be effective in improving the size of the shrimp at harvest.Hydrology of tidal ponds varied with location, but showed a common seasonal pattem.Seasonal variation in temperature was very small. It fluctuated between 27.5 to 32.3°C in tidalponds and 26.9 to 29.9°C in open backwaters.Improvement of nursery habitats with due consideration for biological requirements of the resource will ensure better growth, survival and abundance of the stock.The recruitment, growth and emigration data of prawns from their nurseries can be used successfully for fishery forecasting. projecting juvenile growth forward through time, it is possible to establish, which cohort contributes to offshore fishery each year. So, by interpreting the recruitment and growth data of species in their nurseries with offshore catch data, fishery can be forecasted successfully.

Processing And Frozen Storage Characteristics Of Ray Fillets

Rays, belonging to the class Elasmobranchii, constitute a major fishery in many states in India like Tamil Nadu, Gujarat, Andhra Pradesh, Kerala and Maharashtra. The estimated landings are 21,700 tonnes per annum. Even though the meat of rays is nutritious and free from bones and spines, there is little demand for fresh meat due to the presence of a high urea content. The landings are mainly used for salt curing which fetches only very low prices for the producers. Urea nitrogen constituted the major component (50.8%) of the non-protein nitrogen of the meat. An attempt has been made to standat-dize the processing steps to reduce the urea levels in the meat before freezing by using different simple techniques like dipping the fillets in stagnant chilled water, dipping in chilled running water and dipping in stirred chilled running water. It was found that meat dipped in stirred running water for two hours reduced the urea level of the meat by 62%. The yield of the lateral fin fillets and caudal fin fillets vary with the size of the ray. The drip loss during frozen storage is found to be more in the case of samples frozen stored after the treatment for urea removal by the method of stirring in running water. The samples treated in stagnant chilled water had the lowest drip loss. The total nitrogen was higher in samples treated in stagnant chilled water and lowest in the samples treated in stirred running water. The overall acceptability was high in the case of samples treated with stirred running water and frozen stored

Deep-sea shrimp fishery off Kerala coast with emphasis on biology and population characteristics of Plesionika quasigrandis Chace, 1985

The present study is the first attempt to understand population characteristics of the deep-sea pandalid shrimp, P. quasigrandis and to assess the status of these resources off Kerala coast.Total mortality coefficient (Z) of P. quasigrandis estimated by various methods.Natural mortality coefficient (M) calculated was 0.65 and 1.02 by Pauly‟sempirical formula and Srinaths‟s formula respectively The deep-sea shrimp P. quasigrandis exploited from the present fishing ground and their monetary return has started showing a declining trend. By observing the current yield and economic return, there is no further scope for increasing the catch from the present fishing ground. The study indicated that majority of the deep-sea shrimp trawlers, especially targeted for pandalid shrimps still concentrated off Kollam area (Quilon Bank). Even though researchers had located several potential deep-sea fishing grounds based on exploratory surveys in Indian EEZ , fishermen are unaware of these fishing grounds located and hence sharing the information about new potential deep-sea fishing grounds could avert the possible stock decline due to the intensive targeted deep-sea shrimp fishery in the Quilon Bank. Hence, the present study recommended that part of the effort from existing fishing grounds may be shifted to newly located deep-sea fishing grounds which will help in a sustainableexploitation of deep-sea resources off Kerala coast.

Occurrence of filamentous algae and soil characteristics in the paddy fields of Kuttanad and Kole lands of Kerala

The present work is the study of filamentous algae in the paddy fields of Kuttanad and Kole lands of Kerala. This investigation was initiated by sampling of filamentous algae in Kuttanad during December 2010 to February 2011. A second phase of sampling was done from November 2011 to February 2012. The sampling periodicity corresponded to the crop growth starting from field preparation through sowing, and continued till the harvest. Sampling locations were selected from the active paddy cultivation regions of the six agronomic zones of Kuttanad. The numbers of sampling locations were proportional to the area of each zone. Algae of the Kole lands were collected during from October 2011 to January 2012. It was observed that blue-green algae dominated in both Kuttanad and Kole lands. Thirty two species of blue-green algae and eight species of green algae were identified from Kuttanad. The highest number of algal species was observed from Kayal lands in Kuttanad throughout the cropping season. Among the thirty two species of blue-green algae twenty five species are nonheterocystous and seven species are heterocystous. Twenty eight species of blue-green and six species of green algae were identified from Kole lands, and highest number of species was observed in Palakkal throughout the cropping season. Among the twenty eight species of blue-green algae collected from Kole lands twenty one species are non-heterocystous, and only seven species are heterocystous filamentous algae. Blooms of Spirogyra were observed during the second phase of sampling in Kuttanad and also in the Kole lands. The results of the germination study revealed that the extract of Spirogyra sp. inhibited seed germination and reduced seedling vigour. The growth of the treated seedlings was evaluated by pot experiments. The results clearly showed that Spirogyra sp. can negatively affect the seed germination, seedling vigour, and the yield of rice.