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This paper is to experimentally investigate the mechanical micro machining properties of AL6061-T6 using tungsten-carbide micro end mills. The cutting simulation based on Finite Element Analysis (FEA) method is also conducted to estimate cutting forces, cutting temperature, and minimum chip thicknesses. The simulation results are used for the determination of experimental machining conditions such as depth of cut, feed rates and cutting speeds. A number of slot micro-milling experiments were performed using 400um diameter micro end mills on a 3 Axis CNC machining center attached with a high precision and high speed spindle unit. The machined surface quality, geometric feature shape, cutting burr generation as well as build-up edges are observed in the cutting experiments. Optimum cutting parameters for a better surface quality and smaller burr sizes are suggested.

Micro algae production as a source of fatty biomass that can be used to produce biofuels is a promising alternative that needs to be thoroughly evaluated. The tendency to increase production and energy content and to reduce water usage has had an impact in the development of photobioreactors, due to the versatility of this equipment to control and optimize the production parameters. This system requires an adequate scheme for monitoring and controlling the variables such as temperature, light intensity, carbon dioxide and oxygen supply, in order to guarantee the micro algae growth. This paper presents a control strategy for algae growth in an airlift photobioreactor. A thermodynamic characterization was performed and the dynamic behavior of the system is modeled for system analysis and control. A mathematical model is developed using the equations describing the process. A PID controller is set to evaluate the parameters that control algae growth. The results show that the photobioreactor presents a substantial sensitivity to room temperature changes, and this is considered as the main disturbance of the process. For the dynamic characterization a non-linear differential equations-based model was developed, and after tuning a PID controller it was found that the system was robust to changes in ambient conditions.

The province of Cordoba, Colombia, has a 250.000 tons production of corn, which generate about 45.000 tons of cobs per year, which do not represent any value for farmers. The disposal of this agricultural waste has become a source of contamination because is burned in open areas. On the other hand, this province has a considerable production of raw coal; nevertheless, it is characterized by its high sulfur content (1.65%) and low heat value (5111 cal/gr), as a consequence, it has a limited market, but is still used as a fuel. This study proposes the use of biobriquettes that are a composite fuel prepared from a mixture of biomass (corn cob) and coal in a low die press briquetting machine. They consist of different proportions of milled cob (up to 80%) and coal (up to 40%) mixed with a cassava starch based binder. For the mixtures proximal analysis, including sulfur content and heat values of the material was determined according to their composition. The experimental results showed that the biobriquettes compared with the raw coal have between a 92 to 32% lower sulfur content, while the heat value was reduced by 14 to 29%. Therefore, its use will reduce the amount of burned residue in open spaces and consequently the pollution.