Determination of effective diffusion coefficient of immobilized Baker's yeast invertase in various concentration of PVA-alginate matrix

Baker's yeast invertase is immobilized in PVA-alginate matrix using an improved method. PVA beads were prepared by adding calcium alginate to improve its stability, mechanical and chemical properties. Boric acid was used as the cross-linking agent and additional chemicals consisting of 10% boric acid and sodium sulphate solution was used as a treatment solution to harden the PVA-alginate beads. The determination of the effective diffusion of PVA-alginate matrix the vital step in optimizing the preparation of immobilized and water-soluble biocatalyst. In this study the two-level full factorial design was used to investigate the effect of PVA and boric acid concentrations and diffusions coefficient. Diffusion coefficient (De) is one of the factors that significantly affect the mass transport within the immobilization matrix. De value varies for each concentration of PVA and boric acid. The result concluded that both factors significantly affect the De. A maximum De value of 5.0141 x 10(-5) cm2s-1 was obtained at boric acid and PVA concentraion of 7w/v and 10.5 w/v respectively

THE IMPLEMENTATION OF PORTFOLIO-BASED TEACHING MODEL TO IMPROVE STUDENT’S ACTIVITIES OF ACCOUNTING EDUCATION STUDY PROGRAM IN THE TEACHING AND LEARNING PROCESS OF AUDITING

This research aims at exploring students’ activities during the teaching and learning process of auditing which employs portfolio-based teaching models. The design of this research is action research. The subject of the research was 101 students’ of accounting education study program who take auditing courses in the academic year of 2008/2009. The data were collected through observation and documentation. At the end, the conclusion was taken to improve the activities. The research findings show that the student’s learning activities during the teaching and learning of auditing improve indicated by the 10% improvement of the activities in identifying the cases. Besides, the activities of cases selection for classroom study improve up to 5%. The activities of collecting the study cases improve up to 10%. The activities of presenting the portfolio improve up to 10%, the activities of presenting the data improve up to 10%. The score of student’s portfolio tasks ranging between 86-90 increases up to 31,58%, the score ranging between 81-85 increases up to 3,76%, and the score ranging between76-80 decreases up to 35,35%

Distributed allocation of mobile sensing swarms in gyre flows

We address the synthesis of distributed control policies to enable a swarm of homogeneous mobile sensors to maintain a desired spatial distribution in a geophysical flow environment, or workspace. In this article, we assume the mobile sensors (or robots) have a "map" of the environment denoting the locations of the Lagrangian coherent structures or LCS boundaries. Based on this information, we design agent-level hybrid control policies that leverage the surrounding fluid dynamics and inherent environmental noise to enable the team to maintain a desired distribution in the workspace. We establish the stability properties of the ensemble dynamics of the distributed control policies. Since realistic quasi-geostrophic ocean models predict double-gyre flow solutions, we use a wind-driven multi-gyre flow model to verify the feasibility of the proposed distributed control strategy and compare the proposed control strategy with a baseline deterministic allocation strategy. Lastly, we validate the control strategy using actual flow data obtained by our coherent structure experimental testbed.Comment: 10 pages, 14 Figures, added reference

The importance of design characteristics in walking from student's perspective: a case study in Universiti Kebangsaan Malaysia

Walking is a common form of physical activity, which has a lot of both social and recreational impacts. It is studied as a way of achieving sustainability. Many researchers recommend that walking can increase mental and physical health. Spectators of new urbanism recommend that the good design will encourage walking. There are several characteristics for designing walkable communities, which were frequently described in researches by many authors. In this paper, the four criteria noticed for making walkable university campus include connectivity, accessibility, safety/security and comfort. These criteria have been assessed by gathering survey in the Universiti Kebangsaan Malaysia to find out if these criteria can cause or affect walkability in university campus and it has been supported by previous studies. The result of the survey shows that these criteria are important from students’ perspective as high numbers of the students consider these characters as important for walking activity. The conclusion is to achieve walkable university campus as it will be necessary to evaluate present walking conditions, research walking behavior in different settings and consider these four criteria in designing campus for improving walking condition

Biodiesel production from high FFA rubber seed oil using waste cockles

A two-step heterogeneous catalyzed process of high free fatty acids (FFA) rubber seed oil was conducted to produce biodiesel in lab scale. Acid esterification process was first used to reduced the high FFA rubber seed oil from 78.9% to below 1%. The low cost cockle shell was utilized as a source of CaO heterogeneous catalyst by calcination process and its effect on transesterification process was studied. The optimum yield of 88.06% was obtained for the final product of biodiesel under optimal conditions of 16:1 molar ratio of methanol to oil, 9% catalyst weight percentage with 3 hours reaction time. All fuel properties were analysed according to the ASTM D 6751 standard and found within the requirements

Fuzzy rule-based alertness state classification based on the optimization of EEG rhythm/channel combinations

This paper presents a method for automatically selecting the optimal EEG rhythm/channel combination capable of classifying the different human alertness states. We considered four alertness states, namely 'engaged', 'calm', 'drowsy', and 'asleep'. Energies associated with the conventional EEG rhythms, δ, θ, α, ß and γ, extracted from overlapping segments of the different EEG channels were used as features. The proposed method is a two-stage process. In the first stage, the optimal brain regions, represented by a set of EEG channels, are identified. In the second stage, a fuzzy rule-based alertness classification system (FRBACS) is developed to select the optimal EEG rhythms extracted from the previously selected EEG channels. The IF-THEN rules used in FRBACS are constructed using a novel bi-level differential evolution (DE) based search algorithm. Unlike most of the existing classification methods, the proposed classification approach reveals easy to interpret rules that describe each of the alertness states

High-Order Hybrid Stratified Sampling: Fast Uniform-Convergence Fourier Transform Estimation

This paper considers the problem of estimating the Fourier transform of continuous-time signals from N nonuniformly collected observations. Here, we introduce a new class of Hybrid Stratified sampling scheme in conjunction with a suitable estimator, which can provide the rate of convergence of order \u1d7cf/\u1d475(\u1d7d0\u1d472+\u1d7d1) in the mean-square sense, for signals with \u1d472+\u1d7cf continuous derivatives. Most importantly, it is shown that this rate is not only faster, but also uniform and independent of the analysed frequency (unlike) compared with other existing random-sampling-based techniques. In this paper, we establish the statistical properties of the proposed approach and illustrate its performance analytically as well as numerically