AHP-based procedure for optimization of microwave-assisted blackberry sugar osmotic process

Due to the limitations of single index analysis, the merits and demerits of microwave-assisted permeation process cannot be comprehensively evaluated. However, the analytical hierarchy process (AHP) was applied to optimize the conditions of microwave-assisted diffusion of sugar in blackberry. In this paper, the results of a single-factor experiment were compared with blackberry preserved after the treatment of microwave. An orthogonal rotation test procedure was designed to calculate the composite score of preserved blackberry fruit using AHP, and to determine the optimum processing conditions based on sugar osmosis characteristics. The results showed that the sugar content, vitamin C (VC) content, and color difference of treated blackberry increased with the increase of microwave power, the residence time, and the resulting sugar concentration. The composite grade points are listed to show that the optimum results were as follows: power level, the residence time, and the sugar concentration were, respectively, 210?W, 12?min, and 35%.     

Motion Planning for an Autonomous Compactor in a Waste Landfill Site

Abstract: This paper describes the algorithms and detailed path-planning methodologies developed to enable autonomous spreading and compaction processes in a waste landfilling operation. A given landfill site is spatially decomposed into cells using a recursive spatial decomposition technique. The cell size is determined using a probabilistic model for waste generation. Variation in the amount of waste generated on a given day is handled by a further spatial decomposition of a cell into monominoes. The recursive spatial decomposition processes of a landfill site into cells and each cell into monominoes are accomplished by employing a variant of quadtree data structure. A three-dimensional path plan for an autonomous compactor that considers a variable working gradient in the range of 3:1 to 2:1 is generated for a pair of monominoes. Automatic location of the working place for a compactor is accomplished by a recursive traversal of the quadtree structure. The algorithms have been implemented using a computer-graphic functional interface standard with C-program binding.     

New Biofuel Alternatives: Integrating Waste Management and Single Cell Oil Production

Concerns about greenhouse gas emissions have increased research efforts into alternatives in bio-based processes. With regard to transport fuel, bioethanol and biodiesel are still the main biofuels used. It is expected that future production of these biofuels will be based on processes using either non-food competing biomasses, or characterised by low CO₂ emissions. Many microorganisms, such as microalgae, yeast, bacteria and fungi, have the ability to accumulate oils under special culture conditions. Microbial oils might become one of the potential feed-stocks for biodiesel production in the near future. The use of these oils is currently under extensive research in order to reduce production costs associated with the fermentation process, which is a crucial factor to increase economic feasibility. An important way to reduce processing costs is the use of wastes as carbon sources. The aim of the present review is to describe the main aspects related to the use of different oleaginous microorganisms for lipid production and their performance when using bio-wastes. The possibilities for combining hydrogen (H₂) and lipid production are also explored in an attempt for improving the economic feasibility of the process.     

Numerical modelling of isothermal release and distribution of helium and hydrogen gases inside the AIHMS cylindrical enclosure

Hydrogen is a highly flammable gas and accidental release in confined space can pose serious combustion hazards. Numerical studies are required to assess the formation of flammable hydrogen cloud within confined spaces. In the present study, numerical investigations on the release of helium and hydrogen gases as high-velocity jets and their subsequent distribution inside an unventilated cylindrical enclosure (AIHMS facility) has been carried out as a first step towards numerical studies on hydrogen distribution in confined spaces for safety assessments. Experimental data for jet release of helium at volume Richardson number 0.1 and subsequent distribution has been used as benchmark data. Sensitivity studies on the influence of grid sizes, time-steps and turbulence models are performed. The performance of the validated numerical model is evaluated using statistical performance parameters. Similarity relations are used to determine input parameters for hydrogen jet for corresponding experimental data with helium jets. Finally, the mixing and flammability aspects of hydrogen distribution inside the enclosure are studied using four numerical indices that quantify mixing and deflagration potential of a distribution. It is concluded that the helium experiments can be used for validation of numerical models for hydrogen safety studies and any one of the similarity relationships, viz., equal buoyancy, equal volumetric flow, or equal concentration can be used for assessing the behaviour of hydrogen release and distribution within confined spaces.