The tower crane is an electromechanical equipment that is used for the vertical transport of materials in a construction project and together with the two riggers form the work team to carry out this task. One of the main problems in the construction of multifamily buildings corresponds to the use of the tower crane because vertical transport causes non-contributory times, which is, dead times and waits above expectations. This research analyzes the current vertical transport process and proposes its optimization through some management tools with the aim of improving the productivity of the use of the tower crane by reducing non-contributory times. To this end, the productivity of the work team is recorded in several projects with similar characteristics, then the main problems are selected to analyze them and finally the process is optimized. The results determined that non-contributory times can be reduced by 10% if there is an orderly and continuous process.

<p>This project considers an evaluation of a potential site for a small hydropower plant located in the BioBio north irrigation system, Chile. The purpose was to analyze the potential and constraints in harnessing the energy of an existing infrastructure of irrigation canals for electrical production. The site was analyzed technically, economically and managerially. Before this project nothing was done and therefore the investigations are a main part of the project. A preliminary design for the plant was proposed and the project was named the Minicentral Quillaileo-Mininco.</p><p>Investigations showed a flow variation of 1.62-2.2 m³ per second and a gross head of 44.3 meters. Evaluation gave a possible capacity of 840 kW producing 5 800 MWh annually. Appropriate electromechanical equipment is a Francis turbine with a diameter of 0.5 meter directly coupled to a 1000 rpm synchronous generator. The penstock recommended is a DN 1200 Flowtite GRP. The station is to be fully automatic and connected to the national grid.</p><p>The revenue is based on analysis of the past three year’s electrical market. The costs are based on budget proposals, statistical values and local comparisons. The economical analysis, based on a discount rate of 12% and life span of 35 years, gives a positive cash flow within eight years and a simple payback period of 5 years. The project will have a NPV value of 444 900 USD, IRR 14.70% and B/C of 1.2. Cost per kW will be 2 980 USD. The project is recommended to be further developed.</p>

This project considers an evaluation of a potential site for a small hydropower plant located in the BioBio north irrigation system, Chile. The purpose was to analyze the potential and constraints in harnessing the energy of an existing infrastructure of irrigation canals for electrical production. The site was analyzed technically, economically and managerially. Before this project nothing was done and therefore the investigations are a main part of the project. A preliminary design for the plant was proposed and the project was named the Minicentral Quillaileo-Mininco. Investigations showed a flow variation of 1.62-2.2 m3 per second and a gross head of 44.3 meters. Evaluation gave a possible capacity of 840 kW producing 5 800 MWh annually. Appropriate electromechanical equipment is a Francis turbine with a diameter of 0.5 meter directly coupled to a 1000 rpm synchronous generator. The penstock recommended is a DN 1200 Flowtite GRP. The station is to be fully automatic and connected to the national grid. The revenue is based on analysis of the past three year’s electrical market. The costs are based on budget proposals, statistical values and local comparisons. The economical analysis, based on a discount rate of 12% and life span of 35 years, gives a positive cash flow within eight years and a simple payback period of 5 years. The project will have a NPV value of 444 900 USD, IRR 14.70% and B/C of 1.2. Cost per kW will be 2 980 USD. The project is recommended to be further developed.

M. Tech. (Department of Mechanical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / The subject of maintenance optimisation is not new, and many researchers have explored it. However, it is seen that one optimisation solution cannot be used in all industries. Each industry and equipment thereof are unique as the product streams differ, layouts and operation variables, to name a few. Though Turn-around management is the most used strategy in petrochemical industries. Equipment downtime remains the biggest challenge thus, the purpose of the study was to optimise the maintenance practices used on the critical electromechanical equipment in Sasol Synfuels Catalyst Preparation using both the Analytical Network and Analytical Hierarchy multi-decision approach. Data was collected from the SAP system database, of which the breakdown work orders was obtained from the period of January 2016 to June 2021. The data was collected for each 13 electromechanical equipment identified in the catalyst preparation unit. The applied maintenance strategies employed on the electromechanical equipment in the catalyst preparation unit was also analysed using the Meridium maintenance strategy software tool utilised in Sasol Synfuels. An analysis and identification of the critical equipment within the unit were obtained with the use of two different methods, namely the JADERI, (2019) and AFEFY, (2010) approaches. A theoretical distribution was drawn after that in order to assess the effectiveness of the current maintenance strategy compared to the identified key performance indicators. The theoretical distribution analysis was used to determine the plant utilisation, availability, and maintenance cost. The analytical network and hierarchy process application, and the super decision network model framework, were analysed to obtain the maintenance optimisation solution. Though the ANP and AHP approaches have different problem identification frameworks and cluster dependencies, it is seen that both methods portray more or less similar results. Both methods indicate that in order to achieve an optimised maintenance strategy within the catalyst preparation unit, condition-based maintenance strategy is the most weighed alternative node with 50% for optimal maintenance solution. The least most weighed alternative node is corrective maintenance, weighed at 7%. This is true as corrective maintenance is applied once a breakdown has occurred, of which the aim is to avoid unforeseen breakdowns. Fixed time maintenance is the second most weighed maintenance strategy with 30%, followed then by the operate to failure strategy at 13%. Considering that the operation to failure maintenance strategy is applied based on the consequence of failure and maintenance cost as well as mean time to repair, this is then concluded as practical as RCM priorities predictive and preventative strategies to be employed. It was drawn, for criteria nodes, that the ANP approach resulted in the environmental safety impact as the most important criteria to consider when applying the optimal maintenance strategy in the Sasol Synfuels Catalyst preparation unit. The environmental safety impact was rated at 0.33, followed by availability with a factor of 0.32. The least weighed criteria nodes are then the maintenance cost and MTTR, both with a factor of 0.17. This proves to true considering that the petrochemical industry is considered a high-risk industry as it processes and produces hazardous chemicals The AHP approach structure however, does not consider interdependencies through the criteria and alternative clusters thus the alternative weight could not be defined. The results obtained prove that the ANP approach is the most practical mutli criteria decision making method for maintenance optimisation compared to the AHP approach.