<p>This research is a qualitative descriptive study. The research subjects consisted of female students with introverted personality and female students with extrovert personality. The instruments used in this study consisted of a personality test instrument, interview guidelines, and problem solving tasks (TPM). Data collection was carried out by means of contextual problem solving task-based interviews. The data validity test was conducted by means of time triangulation. The data analysis used refers to the 3 flows of data analysis from Milles &amp; Huberman, namely data reduction, data presentation and conclusion drawing. The results of this study can be concluded as follows. Introverted students mentioned all the information contained in the questions correctly in a halting voice, while extrovert students mentioned all the information contained in the questions correctly and smoothly. The two students solved the questions in two ways even though the methods used were routine procedures that were commonly used by students. In re-examining the results obtained, the two students matched the results obtained with the steps in one method with another method.<strong></strong></p>

The implementation of the 2013 revised curriculum requires students to be able to think critically. The field of mathematics, especially logarithmic material, contains many characteristics, so it requires the ability to think critically to solve the problem. Meanwhile, the ability to think critically is influenced by students' cognitive styles, such as the visualizer and verbalizer cognitive styles. So it is necessary to do research to analyze students' critical thinking skills in solving logarithmic problems viewed from the two cognitive styles. This qualitative descriptive research is used by the teacher as a learning design or strategy so that it can improve students' critical thinking skills according to their cognitive style. The subjects are class X students of SMAN 1 Kamal with visualizer and verbalizer cognitive style. The data analysis technique begins with the VVQ cognitive style test (Visualizer-Verbalizer Questionnaire), problem-solving tests, and interview tests. The results obtained by the visualizer subject in TPM 1 were 14 (good critical thinking category), and TPM 2 scored 12 (adequate critical thinking category). While the verbalizer subject in TPM 1 has a score of 13 (adequate critical thinking category), and TPM 2 is 9 (adequate critical thinking category). Based on the research results, it can be concluded that the critical thinking ability of the visualizer subject dominates compared to the verbalizer subject, because it is able to detect inconsistencies and solve problems systematically.

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A Four-tank system is a multi-input multi-output (MIMO) system consisting of four interconnected water tanks and two pumps. This paper deals with the control design of the four-tank system  using model predictive control (MPC) based filter Kalman. The objective of the control design is to regulate the output of the system towards the desired values. In this work, the optimal control to the system is determined  by means MPC controller where both output and input constraints to the system are explicitly considered. The filter Kalman is used to estimate the state of the system. Simulations by using Matlab are performed to verify the performance of the proposed control design. Simulation results show that the proposed control design can regulate the output of the system towards the desired values.