An investigation on the mechanics of homogeneous expansion in gas-fluidized beds

The Richardson and Zaki (1954, Sedimentation and fluidization. Trans. Inst. Chem. Eng. 32, pp. 35–53.) equation has been used extensively to investigate the expansion profiles of homogeneous gas-fluidized beds. The experimental value of the parameter n appearing in the equation indicates how significantly interparticle forces affect the expansion of these beds, revealing the relative importance of these forces with respect to the fluid dynamic ones. In this work, we modeled the stable expansion of gas-fluidized beds of different diameter, accounting for enduring contacts among particles and wall effects. We solved the model numerically to obtain the bed expansion profiles, back-calculating from them the values of the parameter n. For all the cases considered, we observed that the values of n are higher than those obtained by purely fluid dynamic correlations, such as those advanced by Richardson and Zaki, and Rowe (1987, A convenient empirical equation for estimation of the Richardson and Zaki exponent. Chem. Eng. Sci. 42, pp. 2795.). This effect was more pronounced in beds of smaller diameter. To validate our model, we carried out fluidization and defluidization experiments, analyzing the results by means of the Richardson and Zaki equation. We obtained a reasonable agreement between numerical and experimental findings; this suggests that enduring contacts among particles, which are manifestations of cohesiveness, affect homogeneous bed expansion. This effect is amplified by wall friction

EFFECTS OF SUBSTITUTION OF FAT WITH MELON SEED MEAL ON QUALITY CHARACTERISTICS OF PORK SAUSAGES

A study was conducted in which melon seed meal (MSM) replaced fat at 0, 33, 66, and 100% levels in four batches of pork sausages. The chemical and storage properties, cooking weight losses, and sensory properties, of the sausages were determined in the meat processing laboratory. The results showed that MSM increased both ash and crude protein contents. The highest ether extract (36%) was obtained for batch 1 (control) while the lowest value (25.50%) was recorded for batch 4. The values obtained for refrigeration weight losses increased with increase in MSM while the results for dry matter were statistically insignificant. Batch 3 had the highest cooking weight loss of 0.83% whilebatch one had the lowest value of 0.30%. The values obtained for sensory properties increased with increase in the level of MSM up to 66%. It was concluded that pork back fat can be replaced with MSM in pork sausage without adverse effect on processing yield

In- Vitro Studies on the Nematicidal Potential of Extracts of Seeds of Some Members of Family- Fabaceae in Jos

In-vitro nematicidal potentials of varying concentrations of extracts from seeds of three leguminous plants i.e. Erythrina senegalensis, Leucaena leucocephala and Senna siamea were investigated in juvenile mortality of the second stage larva of Meloidogyne species at the botanical nursery of the University of Jos, between the months of March and April, 2010. The nematodes were extracted from galled roots of tomato obtained from four different farms in Jos, while seeds of the legumes were collected dry from The University of Jos andenvirons. Nematicidal test was carried out with different concentrations of the extract (40g/ml, 60g/ml, 80g/ml; 100g/ml) while distilled water served as control. All the treatments were repeated three times. Live nematodes were counted every twenty-four (24) hours for six (6) days. Phytochemical screening of the seed extracts was also carried out. The results revealed that all the seeds used had nematicidal properties but to varying degrees. Erythrina senegalensis exhibited the highest nematicidal activity while Leucaena leucocephala recorded the least

Growth performance and carcass characteristics of F1 progenies of local x exotic chicken crosses

Growth performance and carcass characteristics of F1 progenies of local hen (Black and Brown normal feathered) and exotic male (Ross 308 and Arbor Acre) strains were evaluated. Base population had 60 dams, 30 each of Brown and Black phenotype and 24 exotic sires, 12 each of Arbor Acre and Ross 308. The experiment had 4 genetic groups – Ross 308 sire x Brown dam (A1R1), Ross 308 x Black dam (A1R2), Arbor Acre sire x Brown dam (A2R1) and Arbor Acre sire x Black dam (A2R2). Growth performance traits measured were final body weight, daily feed intake, average daily weight gain (ADWG), FCR and mortality. Body weight (BW) and linear body traits (LBM) – thigh length (TL), shank length (SL), breast width (BWDT), body length (BL), wing length (WL), keel length (KL), drumstick (DS) were measured as well as carcass and organ traits. Results of growth performance traits showed significantly (P<0.05) higher final BW, ADWG and better FCR in A1R1 progenies. Significant (P<0.05) differences were observed among the four strains for BWDT, DS, BW. KL. SL and WL. It was also observed that F1 progenies of A1R1 recorded significantly (P<0.05) longer TL, SL, KL, WL, and BL and weighed heavier. Carcass and organ traits showed significant (P<0.05) differences among the genotypes. F1 progenies of A1R1 were significantly (P<0.05) different from the other genotypes. It was concluded that genetic variation exists among the progenies for the traits and that Ross 308 x Brown local dams is best suited for improving the local stock in the study area

A systematic review of circular economy research in the construction industry

Purpose While circular economy (CE) is fast becoming a political and economic agenda for global urban development, there are still substantial knowledge gaps in possible strategies to speed up such transition, especially in the construction industry. This study analyses literature surrounding CE to unpack current trends possible future research directions to foster CE implementation in the construction industry. Design/methodology/approach The study undertakes a systematic review of CE literature published between 1990 and 2019. It adopts a five-stage procedure as a methodological approach for the review: formulation of the research question(s), locating and identifying relevant studies, selection and evaluation of studies, analysis or synthesis and results reporting. Findings The findings on CE research in the construction industry show extensive focus on resource use and waste management. There are limited investigations in other areas of construction such as supply chain integration, building designs, policy, energy efficiency, land use, offsite manufacturing, whole life costing, and risk, cost reduction, cost management, health and safety management. The study findings provide evidence that current CE practice fails to incorporate other areas that would facilitate the network of true circular construction industry. Originality/value This research provides a comprehensive overview of research efforts on CE in the construction context, identifying areas of extensive and limited coverage over three decades. Besides, it identifies possible pathways for future research directions on CE implementation, towards the accelerated transition to a true circular construction industry for the benefit of funding bodies and researchers

Sensitivity of Surface Urban Energy and Water Balance Scheme (SUEWS) to downscaling of reanalysis forcing data

Often the meteorological forcing data required for urban hydrological models are unavailable at the required temporal resolution or for the desired period. Although reanalysis data can provide this information, the spatial resolution is often coarse relative to cities, so downscaling is required prior to use as realistic forcing. In this study, WATCH WFDEI reanalysis data are used to force the Surface Urban Energy and Water Balance Scheme (SUEWS). From sensitivity tests in two cities, Vancouver and London with different orography, we conclude precipitation is the most important meteorological variable to be properly downscaled to obtain reliable surface hydrology results, with relative humidity being the second most important. Overestimation of precipitation in reanalysis data at the three sites gives 6-21% higher annual modelled evaporation, 26-39% higher runoff at one site and 4% lower value at one site when compared to modelled values using observed forcing data. Application of a bias correction method to the reanalysis precipitation reduces the model bias compared to using observed forcing data, when evaluated using eddy covariance evaporation measurements. (c) 2017 Elsevier B.V. All rights reserved.Often the meteorological forcing data required for urban hydrological models are unavailable at the required temporal resolution or for the desired period. Although reanalysis data can provide this information, the spatial resolution is often coarse relative to cities, so downscaling is required prior to use as realistic forcing. In this study, WATCH WFDEI reanalysis data are used to force the Surface Urban Energy and Water Balance Scheme (SUEWS). From sensitivity tests in two cities, Vancouver and London with different orography, we conclude precipitation is the most important meteorological variable to be properly downscaled to obtain reliable surface hydrology results, with relative humidity being the second most important. Overestimation of precipitation in reanalysis data at the three sites gives 6-21% higher annual modelled evaporation, 26-39% higher runoff at one site and 4% lower value at one site when compared to modelled values using observed forcing data. Application of a bias correction method to the reanalysis precipitation reduces the model bias compared to using observed forcing data, when evaluated using eddy covariance evaporation measurements. (c) 2017 Elsevier B.V. All rights reserved.Often the meteorological forcing data required for urban hydrological models are unavailable at the required temporal resolution or for the desired period. Although reanalysis data can provide this information, the spatial resolution is often coarse relative to cities, so downscaling is required prior to use as realistic forcing. In this study, WATCH WFDEI reanalysis data are used to force the Surface Urban Energy and Water Balance Scheme (SUEWS). From sensitivity tests in two cities, Vancouver and London with different orography, we conclude precipitation is the most important meteorological variable to be properly downscaled to obtain reliable surface hydrology results, with relative humidity being the second most important. Overestimation of precipitation in reanalysis data at the three sites gives 6-21% higher annual modelled evaporation, 26-39% higher runoff at one site and 4% lower value at one site when compared to modelled values using observed forcing data. Application of a bias correction method to the reanalysis precipitation reduces the model bias compared to using observed forcing data, when evaluated using eddy covariance evaporation measurements. (c) 2017 Elsevier B.V. All rights reserved.Peer reviewe

Numerical simulations of lateral solid mixing in gas-fluidized beds

We investigated the influence of design parameters and operational conditions on lateral solid mixing in fluidized beds adopting the Eulerian-Eulerian modeling approach. To quantify the rate at which solids mix laterally, we used a lateral dispersion coefficient (DsrDsr). Following the usual approach employed in the literature, we defined DsrDsr by means of an equation analogous to Fick׳s law of diffusion. To estimate DsrDsr, we fitted the void-free solid volume fraction radial profiles obtained numerically with those obtained analytically by solving Fick׳s law. The profiles match very well. Our results show that DsrDsr increases as superficial gas velocity and bed height increase; furthermore, it initially increases with bed width, but then remains approximately constant. The values of DsrDsr obtained numerically are larger than the experimental ones, within the same order of magnitude. The overestimation has a twofold explanation. On one side, it reflects the different dimensionality of simulations (2D) as compared with real fluidized beds (3D), which affects the degrees of freedom of particle lateral motion. On the other, it is related to the way frictional solid stress was modeled: we employed the kinetic theory of granular flow model for the frictional solid pressure and the model of Schaeffer (1987) for the frictional solid viscosity. To investigate how sensitive the numerical results are on the constitutive model adopted for the frictional stress, we ran the simulations again using different frictional models and changing the solid volume fraction at which the bed is assumed to enter the frictional flow regime (ϕmin)ϕmin). We observed that DsrDsr is quite sensitive to the latter. This is because this threshold value influences the size and behavior of the bubbles in the bed. We obtained the best predictions for ϕmin=0.50ϕmin=0.50. The results show that accurate prediction of lateral solid dispersion depends on adequate understanding of the frictional flow regime, and accurate modeling of the frictional stress which characterizes it