Vibration is one of the most annoying problems faced during metal cutting operation, and it occurs frequently in manufacturing industries. The vibration level depends on many different parameters such as material type, rigidity of tooling structure, cutting data and operation mode. In milling the cutting process subjected to the tool vibrations having a milling tool holder will most likely result in high vibration levels. These vibrations have a consequence of reduced tool life, poor surface finish and sound distributions. This study presents a new approach of localization for an elastic periodic cutting tool holder of milling machine. A numerical model has been developed to describe the structure of the cutting tool holder. On the other hand, the behavior of periodic holder is investigated numerically. This paper examined the dominating milling vibration components and identified these vibrations which are related to structural dynamic properties of the milling tool holder.
Aims: This paper attempts to improve automatic temporal change detection on a pair of beans images, acquired before and after storage under high temperature (≥ 25°C) and high relative humidity (≥ 65%), conditions that promote « Hard-To-Cook » phenomenon. Study Design: Image processing, Hard-To-Cook beans. Place and Duration of Study: Laboratory of Modelisation, Image Processing and Applications Research (MOTRIMA) Department of Electrical Engineering Energetic and Automatics, Laboratory of Biophysics and Food Biochemistry Department of Food Science and Nutrition of National School of Agro-Industrial Sciences (University of Ngaoundéré, Cameroon), Institute of Agricultural Research for Development (IRAD) between August 2009 and March 2010. Methodology: We want to get a robust extracting seed in acquired images and a good dissimilarity parameter for temporal change detection on a pair of textured images. To reach this goal, we analyze the characterization of textural properties and space color which are more relevant to textured beans seeds. We use wavelet transform and apply fuzzy logic segmentation. We define a confidence limit for the dissimilarity parameter before analyzing its evolution during storage of beans seeds. Finally we correlate this parameter with another Hard-To-Cook indicator. Results: After many tests, Daubechies 2(db2) wavelet family in RGB space allowed best extracting beans seeds in scene with fuzzy-c-means segmentation. The global intensity variation was a pertinent parameter for dissimilarity detection between two images. We obtained highly correlation between this parameter and cooking times beans (-0.96; -0.88; -0.72 respectively in Red, Green and Blue color space). Conclusion: The global intensity variation in red color space allowed the determination level of browning beans seeds as indicator of their Hard-To-Cook degree.
Aims: The scope of the model lies in its applicability in the management inventories of time-quadratic demand. It is also seen that large pile of goods displayed in a supermarket will motivate the customer to buy more. So the presence of inventory has a motivational effect on the people around it. Also there may be occasional shortages in inventory due to many reasons. Therefore, we develop an EOQ model for the inventory of a deteriorating item, taking demand rate and allowing shortages in inventory. Study Design: This paper presents an inventory model for deteriorating items with quadratic demand. In the model, shortages are allowed and partially backordered. The backlogging rate is a variable and dependent on the waiting time for the next replenishment. A numerical example is taken to illustrate the model and the sensitivity analysis is also studied. Methodology: Our purpose is to devise a mathematical model on inventory management taking all these factors into consideration. Results: Convexity condition of the cost function is established to ensure the existence of unique point of minimum. Conclusion: The proposed model can be extended in several ways. For instance, we may extend the demand function to stochastic fluctuating demand patterns or stock-dependent demand rate. Finally, we could extend the model to incorporate some more realistic features such as quantity discounts, permissible delay in payments, time value of money and inflation etc.
This paper presents a provisional design proposal for the modification of the numbering and address representation of Internet Protocol 4 (IPv4), the Internet address system nearing exhaustion, based on biology. Biologically-inspired designs have been applied in diverse technological fields with varying degrees of successes. The paper proposes the expansion of IPv4 addresses by the concatenation of twelve 8 bit suffixes to each IPv4 address using numbers derived from DNA sequences. The author outlines a design proposal for the modification of the addressing system of the network layer in the TCP/IP hierarchy. This scheme, if deemed possible, could see the creation of at least 6.4 × 1026 unique addresses and prolong the usefulness of IPv4, beyond the projected operational time frame of ten years.
Aims: The knowledge of water sorption Isotherm gives information about water activity of foods; to investigate chemical reactions during drying and storage. This study therefore, was to determine the sorption properties of pupuru flour during storage at ambient temperature. Study Design: Research study. Place and Duration of Study: The study was carried out in the Food Processing Laboratory of Food Science and Technology Department of Federal University of Technology, Akure, between April 2009 and December 2009. Methodology: Adsorption characteristics of pupuru flour, a fermented cassava product, were determined at room temperature of 27°C using the static gravimetric procedure. Samples were equilibrated in desiccators containing tetraoxosulphate (VI) solution of known water activity (0.1-0.6). The data obtained were fitted to four moisture sorption models, namely Henderson, Chung Pfost, Oswin and Caurie for their predictive capabilities. Results: The coefficients of determination varied from 0.881- 0.993. Both Henderson and Oswin models gave the most suitable models for describing the sorption data. The appropriate constants in the sorption equation were determined by regression analysis at temperature of 27°C. A comparison of the EMC curves showed that the toasted pupuru sample had lower equilibrium moisture contents than the smoked and oven dried samples at lower aw but higher EMC at higher aw. Conclusion: It can also be concluded that the models are quite useful in assessing the storage stability of pupuru flour. The toasted pupuru flour has a higher sorption capacity and longer storage stability at higher aw of the tropics than the other two samples at atmospheric temperature of 29°C.
Aims: To determine the level of some chemical parameters in samples of 5 potable water sources namely, tap, borehole, open well, sachet water, and bottled water. To further compare results with WHO (2011) standards to ascertain safety of water sources within the study area. Study Design: Collection and analysis of samples from potable water sources. Place and Duration of Study: 16 settlements within the Abuja Municipal Area Council (AMAC) constitute the study area. Sample collection took place during the dry season months of January – March 2011 to avoid the possibility of contamination of some water sources from runoff. Methodology: Stratified random sampling technique was adopted for sample collection from 16 settlements; one each from four identified categories of settlement within the study area. For data analysis, mean, standard deviation and minimum and maximum values were computed for every chemical parameter for each sampling location. Results: The results reveal that pH, NO3, Cu, Al, TOT-N and Fe are not limiting factors to the quality of drinking water in the study area; the levels of Cd, Bicarbonate, NH4-N, Mn, Zn, As, Cr and Pb concentration in water samples are above the safety limit set by the WHO (2011); pH, SO4, NO3-, TOT-P and HCO3-, Cl in open well samples have slightly higher values than in samples of the other four sources of potable water. Borehole and sachet water samples have slightly higher SO4 values; bottled and tap water samples have the highest values of HCO3-, among others. Increasing anthropogenic activities that result in pollution are attributed to these levels of water contamination at the study area. Conclusion: There is need for Nigeria’s National Agency for Food and Drug Administration and Control (NAFDAC) to focus on promoting the safety of potable water, most especially the sachet and bottle water sources; periodic, unannounced inspections should be conducted on facilities producing sachet and bottled water to ensure that standards are highly maintained. Lastly, efficient management of water resources in Nigeria’s urban and peri-urban centers is increasingly becoming necessary if the health and well-being of the residents is of utmost importance.
A study was conducted to determine the median lethal concentration of neem for common carp (Cyprinus carpio) as a non-target organism. Five test concentrations and a control were used in triplicates to determine the 72 hour MLC of neem gold pesticide. With the increase of dose concentration (0.05, 0.07, 0.09, 0.12 and 0.17 ml/L-1) and exposure duration significant increase in the mortality level was noticed. The 72 h LC50 values (with 95% confidence limits) of Neem Gold for common carp juvenile were found to be 0.09799 ml/L-1.
Aim: Investigations were carried out to evaluate the performance of a high grade low heat rejection (LHR) diesel engine with air gap insulated piston, air gap insulated liner and ceramic coated cylinder head (ceramic coating of thickness 500 microns was done on inside portion of cylinder head] with different operating conditions (normal temperature and pre-heated temperature) of Mohr oil based bio-diesel (MOBD) with varied injection pressure and injection timing. Study Design: Performance parameters of brake thermal efficiency, exhaust gas temperature and volumetric efficiency were determined at various values of brake mean effective pressure (BMEP). Methodology: Exhaust emissions of smoke and oxides of nitrogen (NOx) were recorded at different values of BMEP. Combustion characteristics at peak load operation of the engine were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software package. Results: Conventional engine (CE) showed deteriorated performance with biodiesel operation, while LHR engine showed improved performance at recommended injection timing and pressure of 27°bTDC (before top dead centre) and 190 bar respectively. The performance of both version of the engine improved with advanced injection timing and at higher injection pressure when compared with CE with pure diesel operation. The optimum injection timing was 31°bTDC for CE while it was 30°bTDC for LHR engine using biodiesel operation. It was also observed that peak brake thermal efficiency increased by 14%, volumetric efficiency decreased by 8%, smoke levels decreased by 6% and NOx levels increased by 47% with MOBD operation on LHR engine at its optimum injection timing, when compared with pure diesel operation on CE at 27°bTDC.
This study models the egress behaviour of passengers at a transportation access point with multimodal service with the objective of evaluating the delays associated with their departure from the access area. Passengers arriving at this access area have the taxi mode, minibus mode and the bus mode to choose from. A discrete choice model with the utility function based on mode fare and transit time was used to describe the egress behaviour of passengers. The resulting queues at the access area for the three modes were transient in character with time-varying arrival λ(t), time varying service rates µ(t), a truncated bulk service single channel with first-in-first out queue discipline. The queuing systems were described by M/M*/K/FIFO with random clearing of all queued taxi and minibus passengers. A computer simulation package using Runge-Kutta numerical methods was used to solve the set of linear differential equations developed for the three transport modes serving the area. The simulation models were tested with field data collected from the access area on all trips made during the study period and were analysed at fifteen minute time intervals. The probabilities of delay predicted by the simulation models agreed closely with field observations. The chi-squared test indicated that there were no significant differences between the models and the field values at the 95% significant level. Passengers at the access area experienced an average delay of 16.4minutes, 12.4minutes and 23.5minutes for the taxi, minibus and bus modes respectively. The methodology would need to be tested with data from other areas with similar demand characteristics to build confidence into it.
Worldwide National policies on higher education are giving increasing importance to improve the quality of education on offer. Consequently, the evaluation of teachers’ performance in teaching activity is especially relevant for the academic institutions. It helps to define efficient plans to guarantee quality of teachers and the teaching learning process. In this paper, a soft computing model for academic performance of the teachers in technical institutions based on teaching activity series of qualitative reports is presented. We have proposed a Fuzzy Expert System for evaluating teachers overall performance based on fuzzy logic techniques under “uncertain facts” in the decision making process. A suitable fuzzy inference mechanism and associated rule has been discussed. It introduces the principles behind fuzzy logic and illustrates how these principles could be applied by educators to evaluating teachers’ performance. This model will help to write the Annual Confidential Reports of all the employees of an organization.