Open Access Original Research Article

Optimal Third Order Rotatable Designs Constructed from Balanced Incomplete Block Design (BIBD)

Jeremy C. Rotich, Mathew K. Kosgei, Gregory K. Kerich

Current Journal of Applied Science and Technology, Page 1-5
DOI: 10.9734/CJAST/2017/34937

In the design of experiments for estimating statistical models, optimal designs allow parameters to be estimated without bias and with minimum variance. Optimal designs are experimental designs that are generated based on a particular optimality criterion and are generally optimal only for a specific statistical model. The purpose of this study therefore was to investigate the optimality criteria for third order rotatable designs (TORD) constructed from balanced incomplete block design (BIBD). Specifically the study obtained alphabetic optimality criteria for specific TORD in three, four, five and six factors. From the existing TORD constructed using BIBD, the design matrix, moment matrix and information matrix considering full parameter system were obtained. Evaluation of the alphabetic optimality criteria was done. However, all the designs under investigation were found to be E-optimal. E-optimality maximizes the minimum eigenvalue of the information matrix. Optimum TORD from BIBD can be applied in real life experiments.

Open Access Original Research Article

The Square of PErceived ACtion Model (SPEAC Model) Applied in Digital Ethnography for Work Activity Analysis: Performance and Workers’ Perception

Philippe Fauquet-Alekhine, Saadi Lahlou

Current Journal of Applied Science and Technology, Page 1-13
DOI: 10.9734/CJAST/2017/34985

The SPEAC protocol using first-person perspective ethnography and subsequent replay interviews was applied to analyze work activities at a French nuclear power plant during real operating situations of Operations shift teams (15 situations and 30 participants, about 1950 min. video recordings and 2400 min. audio recordings). Results were compared with those obtained with the standard method applied in the French nuclear fleet (Systemic Approach to Training: SAT). Both SPEAC and SAT methods provided knowledge and know-how necessary to perform work activities. Following each analysis, participants were presented with a questionnaire for assessment of the method. Items addressed efficiency, constraints, extended application to colleagues or other activities. SPEAC method showed a significantly higher level of identification of knowledge and know-how per activity (from 1.9 to 9 times more) than SAT and at a lower cost. The SPEAC method evaluation by participants was positive, with a good consistency of answers. Trainees considered that i) analyzing the subjective film was perceived as a real added value compared to a classic method (without subjective film, ii) the new method induced faster progress iii) the overall perception was positive) iv) the method was worth being deployed to other activities. Bias, limits and perspectives are discussed.

Open Access Original Research Article

Transition Curve with Smoothed Curvature at its Ends for Railway Roads

Wladyslaw Koc

Current Journal of Applied Science and Technology, Page 1-10
DOI: 10.9734/CJAST/2017/35006

In the paper, in view of a railway ballasted track, a new concept of transition curve of linear form of curvature along its length and smoothed extreme regions is presented. For this purpose use has been made of an original, universal method for identifying transition curves by means of differential equations. Some general curvature equations for three regions investigated have been determined to be followed by appropriate parametric formulae. The possibility of determining the rectangular coordinates by numerical integration has been indicated. Taking into consideration the criterion of practical execution, and on account of very small horizontal ordinates in the initial region, a suggestion is made to reduce the length of the extreme regions and for such a case some particular theoretical relations have been worked out.

Open Access Original Research Article

Investigating Effect of Zinc Content on the Mechanical and Corrosion Responses of Al6063-SiC Composite

O. O. Ajide, A. O. Otesile, T. A. O. Salau, O. S. Ismail, O. M. Oyewola

Current Journal of Applied Science and Technology, Page 1-10
DOI: 10.9734/CJAST/2017/34886

Corrosion susceptibility of Al6063-SiC based composites is attracting unceasing concerns among researchers. The motive of this work was to investigate the influence of zinc content on the corrosion resistance and mechanical responses of Al6063-SiC composites. Zinc was incorporated into the composite at 2, 4, 6, 8 and 10% volume fractions using the Two-step stir casting method. Thereafter, mechanical response, optical microscopy and corrosion tests were carried out. The hardness tests revealed a general decrease pattern in the Brinell Hardness Number (BHN) of Al6063-SiC-Zn composite as the percentage of zinc increased. However, the Impact and tensile strengths of Al6063-SiC-Zn composite increased as the volume fraction of Zn increased. The relative enhancement in the mechanical responses of Al6063-SiC-Zn composites can perhaps be attributed to the manifestation of thickened and dense grain lines observed in the micrographs as the concentration of zinc in the composite increased. Corrosion tests in both sulphuric and saline media revealed a good influence of zinc on the composite. Therefore, the choice of zinc alloying element has potential for enhancing corrosion resistance of Al6063-SiC-Zn composites in brine and acid based environments with satisfactory contributions to their mechanical behaviours.

Open Access Original Research Article

Variability of Sensory Acceptance and Flavors of the Inflorescence Sap Deriving from Four Widespread Cultivars of Coconut (Cocos nucifera L.)

Konan N’Guessan Ysidor, Konan Konan Jean-Louis, Assa Rebecca Rachel, Biego Godi Henri Marius

Current Journal of Applied Science and Technology, Page 1-10
DOI: 10.9734/CJAST/2017/33059

Aims: The study focuses on the sensory properties of the coconut inflorescence sap for promoting its consumption by populations.

Study Design: Four widespread coconut cultivars sampled, namely Malaysian Yellow Dwarf (MYD), West African Tall (WAT), and the improved hybrids MYD x WAT (PB121+) and Cameroon Red Dwarf x Rennel Island Tall (PB113+). Sap collected from young unopened inflorescences. Acceptance and descriptive sensory flavors variability of the sap samples assessed using 75 and 15 panelist tasters, respectively.

Place and Duration of Study: Marc Delorme Research Station for Coconut (MDRSC), from the National Centre of Agronomic Research, Abidjan, Côte d’Ivoire, between November 2014 and March 2015.

Methodology: Six healthy adult coconut trees (over nine years of age) randomly selected from experimental plots of the MDRSC. Unopened inflorescences (of rank 8) selected per palm to produce the coconut sap. Coconut sap harvested twice a day and sap volumes gathered per cultivar and kept fresh into a freezer till the sensory assessment. The analyzes targeted the acceptance of the coconut sap samples from the consumers, then the estimation of the sweet, salty and sour sap flavors degrees using a 7 points rating scale. Data were collected through written rating after tasting trials achieved according to standard directives at the Technology Laboratory of the MDRSC, using 75 tasters for the hedonic characterization and 15 tasters for the sensory profile.

Results: The tasting panelists enjoyed the coconut saps resulting from the 4 overall cultivars, but in various proportions ranging from 67.86% (WAT) to 92.86% (PB113+). The samples from WAT and PB113+ are more accepted, with full enjoyment mentioned by 48% and 62% panelists, respectively. The sweet flavor is felt with degrees ranging between 5.67/7 (PB113+) and 6.39/7 (MYD). The salty and sour flavors are felt with lower indexes oscillating between means of 2.03 and 3.21 from the 7 points rating scale.

Conclusion: The MYD cultivar produces most sweetened sap whereas that of PB113+ hybrid is more appreciated for consumption. Both WAT and PB113+ cultivars could be promoted in coconut sap production for fresh drink. Besides, the sweeter sap of MYD and PB121+ could be processed into other coconut by-products such as vinegar, alcohol, syrup or coconut sugar.

Open Access Original Research Article

Impacts and Feedbacks of Land Use and Land Cover Patterns in Landscape on Ecosystem Processes and Microclimate: Case of a Cacao-Based Agroforestry System

Agele Samuel, Adejobi Kayode, Charles Friday, Ogunleye Abel, Olayemi Lauretta

Current Journal of Applied Science and Technology, Page 1-11
DOI: 10.9734/CJAST/2017/31432

Climate change is a major threat to human welfare, biodiversity and ecosystem services. Climate change calls for changes in management of land and water resources. The coupling of and feedback from land use and land cover  patterns in landscapes with ecosystem processes (nutrient cycling, water use, evaporation, heat and heat islands) and microclimate is known. Although information is inadequate from tropical land use practices such as intercropping, land rotation fallowing and agroforestry systems. However, understanding of the interactions of land cover patterns with ecosystem processes from cacao-based agroforestry landscapes may be useful in the development of strategies to advance adaptation and resilience to extreme weather shocks. Year round measurements  were made of soil carbon contents and respiration, microbial biomass C, soil moisture and temperature regimes, soil organic matter pool, species specific carbon stocks, stand biomass, microclimatic-gradients in an agriculturally cultivated field and cacao-based agroforestry system of different ages. Our findings showed that land cover patterns and other elements in cultivated agricultural field and cacao-based agroforestry landscape modulated land surface-atmosphere fluxes and stocks of carbon, other biogeochemical cycles and microclimatic conditions. The results indicated that the high potentials of net gains in carbon (sources and sinks) from cacao-based agroforestry system is a promising CO2 mitigation strategy. Cacao-based agroforestry ecosystem contributes to terrestrial carbon budget (carbon stocks and fluxes), ameliorated weather conditions in addition to other ecological benefits and ecosystem health while the resultant enhanced carbon sequestration will reduce global warming. This information can be incorporated into existing strategies for addressing ecosystem (vegetation and soil) degradation and for agricultural, and forest land use plans in support of climate change adaptation and for rainforest ecosystem conservation.

Open Access Original Research Article

Modeling and Simulation of Hybrid Maximum Power Point Tracking for Solar Power System

Ali Jasim, Yuri Shepetov

Current Journal of Applied Science and Technology, Page 1-10
DOI: 10.9734/CJAST/2017/35100

This paper presents, a Hybrid Maximum Power Point Tracking (HMPPT) controller for solar power system is modeled using MATLAB Simulink. The model consists of PV module, boost converter, and HMPPT controller and load. The proposed hybrid method is a maximum power coefficient (KP) and modified hill climbing MPPT method. The boost converter model is allowed the input voltage of the converter, i.e. output voltage of PV is changed by varying the duty cycle, so that the hybrid maximum power point could be tracked when the environmental changes. The increasing efficiency of the solar power system is important engineering task. From the experiment, the developed model comforms with the circuit model provided by MATLAB Simulink Power Simulation. The power system was simulated in single (autonomous) power system worked on own load with R=25, 50, 100 Ohm dependence Pout from duty cycle D. Existing methods of maximum power point tracking of such systems not always can  to search surely for maximum power point if there are existing  some local maximums of power. It can be if illumination of few non-oriented solar panels are different. Further, the simulation results show that the developed model performs well in tracking the hybrid maximum power point of the PV module using modified hill climbing (HC) Algorithm and maximum power coefficient (KP).