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<p class="MsoNormal" style="margin: 0cm 12.6pt 6pt 18pt; text-align: justify; text-indent: 27pt;"><span style="font-size: 10pt;" lang="en-us" xml:lang="en-us">This study was aimed at analyzing risk factors of nutritional anemia among new students of Bogor Agricultural University (IPB). A logistic regression model for 1907 new students’ record data matched with health record data was selected and applied on anemia risk factors analysis. The result showed that 10.9% and 21.4% of the students were suffering from nutritional anemia and proteinuria respectively. The risk factors of nutritional anemia among the new students of IPB are sex, age, family income and proteinuria status. The nutritional anemia risk is higher among female students (OR = 1.36); among younger age (age &lt; 18 year); among students from low income family (OR = 1.70); and students suffered from proteinuria (OR = 1.49). This implies that the regular monitoring and controlling of both anemia and proteinuria among the students by Polyclinic of IPB are urgently required.  </span></p>

During its operation, a photovoltaic system may encounter many practical issues such as receiving uniform or non-uniform irradiance caused mainly by partial shading. Under uniform irradiance a photovoltaic panel has a single maximum power point. Conversely under non-uniform irradiance, a photovoltaic panel has several local maximum power points and a single global maximum power point. To maximize energy production, a maximum power point tracker algorithm is commonly implemented to achieve the maximum power operating point of the photovoltaic panel. However, the performance of the algorithm will depend on operating conditions such as variation in irradiance. Presently, most of existing maximum power point tracker algorithms work only in a single condition: either uniform or non-uniform irradiance. This paper proposes a new maximum power point tracker algorithm for photovoltaic power generation that is designed to work under uniform and partial shading irradiance conditions. Additionally, the proposed maximum power point tracker algorithm aims to provide: (1) a simple math algorithm to reduce computational load, (2) fast tracking by evaluating progress for every single executed duty cycle, (3) without random steps to prevent jumping duty cycle, and (4) smooth variable steps to increase accuracy. The performances of the proposed algorithm are evaluated by three conditions of uniform and partial shading irradiance where a targeted maximum power point is located: (1) far from, (2) near, and (3) laid between initial positions of particles. The simulation shows that the proposed algorithm successfully tracks the maximum power point by resulting in similar power values in those three conditions. The proposed algorithm could handle the partial shading condition by avoiding the local maxima power point and finding the global maxima power point. Comparisons of the proposed algorithm and other well-known algorithms such as differential evolution, firefly, particle swarm optimization, and grey wolf optimization are provided to show the superiority of the proposed algorithm. The results show the proposed algorithm has better performance by providing faster tracking, faster settling time, higher accuracy, minimum oscillation and jumping duty cycle, and higher energy harvesting.

This paper presents a sliding mode control using a nonlinear sliding surface (NSS) to design a robust tracking controller for a quad-rotor helicopter. An NSS is designed to provide a variable damping ratio for the closed-loop dynamics of the system to achieve a quick response and low overshoot performance. The dynamics of the quad-rotor helicopter is derived by the Newton-Euler formulation for a rigid body. The global stability of the proposed control strategy is guaranteed on the basis of the Lyapunov stability theory. The robustness and effectiveness of the proposed control system are demonstrated experimentally, providing comparative results with a conventional linear sliding surface. The NSS provides robust tracking control under significant wind gusts.

This paper proposes a time-varying sliding surface for a second-order sliding mode controller to improve the control performance and energy efficiency of a quad-rotor helicopter. The time-varying sliding surface is designed with a nonlinear function to provide varying properties of the closed-loop dynamics in order to reduce energy consumption. It is shown that the second-order sliding mode technique, known as a generalized super twisting algorithm, providing a robust controller and a nonlinear sliding surface is effective in reducing the energy consumption. A Lyapunov stability analysis is described to prove the stability of the proposed method. The effectiveness and reliability of the proposed method are evaluated by performing experiments several times using a quad-rotor helicopter experimental testbed under wind disturbance.

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