Algae are good plants as raw materials for biodiesel. Chlorella Vulgaris is one of the most economical algae to produce biodiesel since it is rich in carbohydrates, require no special care, and easy to grow. Algae oil for biodiesel production is obtained through fairly long processes, one of which is the lipid extraction. Mathematical model can be used to obtain optimal results. The optimal control theory itself is concerned with the analysis of controlled dynamic systems, in which a system is directed from configurations given to some desire target by minimizing or maximizing some criteria. In this study, LQR formulation has the advantages of easy to analyze and implementation. In comparison, optimum control is performed using the PMP method, to obtain the best control of the dynamic system from the initial state to the end, i.e by maximizing the objective function. This method is a better method than the LQR method. Optimal control is performed in order to optimize the yield of lipid concentration in the solvent flow (Cs), in the microalgae particles (Cp), and minimizing the volume of solvent (v). From the simulation, it is found that the PMP method is more optimal in this system compared to the LQR method.
Microalgae is an alternative energy source that considered capable of answering fuel oil scarcity problem. The growth of microalgae plays an important role in biomass production. One of the factors that influence the growth of microalgae is the control of light intensity so that it is necessary to adjust the intensity of the incoming light to produce maximum biomass. Control the intensity of light on the microalgae growth can be modelled in the form of differential equations and can be seen as a system. The control method chosen in this study was a linear quadratic regulator (LQR), as well as a comparison with the previous method, namely Pontryagin minimum principle (PMP). The simulation results show that at LQR an increase in the amount of biomass reaches 91.77% from initial condition. While the PMP has doubled from its initial condition.
The library is a learning infrastructure that must be available in every school. Libraries provide information and knowledge needed by students. The development of technology and information is expected to have an impact, namely the effi ciency and eff ectiveness of the implementation of work. One way is to change the manual system into a computer-assisted system supported by internet technology. In this community service activity, a web-based library application has been designed and built at SMAN 1 Jombang. Application development uses the Waterfall model which consists of 4 stages, namely system requirements analysis, system design, implementation, and maintenance. The library application is built using the Code Ignaiter framework with the Hypertext Pre-Processor (PHP) programming language while the database uses MySQL.The benefi t of this application is to address the needs of students for book searches and book ordering, while for school library offi cers it manages the circulation of book borrowing and reporting. The result of community service that has been implemented is a Web-based library application at SMA Negeri 1 Jombang to improve the quality of library management.
<p><em>In this study, a supply voltage at peak breaker is made to do the plug discharge test. Plug discharge (capacitor residual voltage) testing on IEC 60335-1 is a challenge for engineers. Requirement for the test are disconnecting supply voltage from the Equipment Under Testing (EUT) at its peak value. Most laboratory did this test manually, so the test might be carried out repeatedly so that the requirement is obtained. This system is using zero crossing detector and timer for detect the peak waave. The zero crossing detector circuit find the time when the voltage cross the 0 volt as the initial reference for termination. Microcontroller with Timer feature is used to delay the disconnection time from the 0 volt point or a quarter period of the power line. Relays are used as voltage breakers. From the experiments, it is necessary to add a compensation time due to the relay response time so that the system could do the supply voltage break at it’s peak wave. This system works properly with error 1.6% and with this means plug discharge testing could be finished in only one trial.</em></p>
Abstract. There are so many benefit of algae. One of them is using for renewable energy and sustainable in the future. The greater growth of algae will increasing biodiesel production and the increase of algae growth is influenced by glucose, nutrients and photosynthesis process. In this paper, the optimal control problem of the growth of algae is discussed. The objective function is to maximize the concentration of dry algae while the control is the flow of carbon dioxide and the nutrition. The solution is obtained by applying the Pontryagin Maximum Principle. and the result show that the concentration of algae increased more than 15 %.
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