1. Factors Affecting the Ability to Depict Mental Models of Chemical Solutions Among Chemistry Students

    Mary Joy M. Villamora

    Philippine Science High School – Central Visayas Campus, Talaytay, Argao, Cebu 6021 Philippines.

    Abstract: This was a descriptive study to determine the factors affecting the ability to depict mental models of chemical solutions among General Chemistry II students of Philippine Science High School-Central Visayas Campus during SY 2013-2014. Thirty students were randomly selected as respondents. Their profiles which consisted of their sexes and grades in General Chemistry I were obtained. The students’ attitude towards Chemistry, as well as their ratings in the prior conception test and in their depiction of mental models of chemical solutions were determined. The probing of the mental models was done using an interview protocol that included the use of a variety of common chemical solutions and focus cards that depicted model use (Unal, Calik, Ayas, & Coll, 2006; Jansoon, et al., 2009). Findings revealed that 1) the more able respondents were able to present consistent representations of chemical solutions at each level of representations: the macroscopic, submicroscopic and symbolic levels. In contrast, the less able respondents were able to depict in an unrelated manner the concepts at the three levels. It was also shown that 2) the following variables were significantly correlated with the respondents’ ability to depict mental models of chemical solutions: General Chemistry 1 grade, r(28)= 0.370, p = 0.044; attitude towards Chemistry, r(28)= 0.380, p = 0.038; and prior conceptions rating, r(28)= 0.384, p = 0.036; and, 3) there is no significant difference between males (M= 75.5553, SD= 7.85312) and females (M= 73.3333, SD= 7.84207)  in terms of their ability to depict mental models of chemical solutions, t(28)= 0.775, p = 0.445. Therefore, one’s ability to depict mental models of scientific concepts can be enhanced by certain factors. In this study, the attitudes of students towards Chemistry, their prior conceptions of the subject matter and performance in prerequisite subjects are key determinants in their performance to depict mental models of chemical solutions.

    Keywords: chemistry education, chemical solutions, mental models.

    Pages: 97 – 114 | Full PDF Paper
  2. Improvement in the Supply System of Wheat Flour Silos

    Fabricio Henrique Bernardo Sant’ana1, Anderson Figueiredo da Costa2-1

    1. Production Engineering, University São Judas Tadeu, Taquari Street 546, ZIP 03166-000, São Paulo, Brazil.
    2. Engineering and Materials Science, Federal University of São Paulo, Rua Talim 330, 12231-280, São José dos Campos, Brazil.

    Abstract: This study was carried out based on the tools used in the process of wheat flour silos and adapted to a food industrial scenario with the purpose of defining the capacity of the supply process of a food factory, and if there are conditions for a possible expansion and the creation of a new line of loaf breads, since the demand of a particular brand is growing, in addition to opportunities for gain and expansion in the current market. Initially, we carried out surveys of times and methods, movements of people and machines, we acquired information and specifications about the efficiency of the machines, based on that we calculated the efficiency of our system, from there, the step was to calculate the demand for flour that the factory needed so that there was no failure in any production line, and we correlated the capacity of the system with the need to consume the factory’s main raw material. With the deepening of the study, we realized there is work idleness in the Wheat Flour Silos supply sector, and we implemented some Lean Manufacturing tools, such as DMAIC, analysis tools. In the implementation phase of improvements in the DMAIC cycle (Improve), we implemented in the sector improvements in handling, lean times and some pillars of Total Productive Maintenance (TPM), beginning to start up some autonomous maintenance activities, such as inspection routes, failure analysis, preventive and predictive maintenance, in parallel with operational training and Work Safety dialogues weekly (SHE Pillar). To reach the success in the project, we used as reference the analysis some works of reputed names from the academic and industrial scene, as well studies, reports and technical information from manufacturers and engineers who designed the current system.

    Keywords: Silo, food, TPM.

    Pages: 115 – 131 | Full PDF Paper