A unique phenomenon in physics has been revealed. Due to internal mechanical stress and defects the surface electrical conductivity of metallic objects can be modified. This conductivity modification even exists for some time after the failure of the mechanical attack. The data presented in this paper proves the effectiveness of the discovered phenomenon. Designed microwave sensor reveals remote closed metal defects. Experiments in detecting cracks within rail-wheel rims were one of the first applications.
There are few systems of special education that are as comprehensive as the one in place in the United States. This paper compares the special education services available to students with disabilities in China, India and Thailand with the services for students with disabilities in the United States. The first part of the paper is a review of the literature on special education in the aforementioned countries. This is followed by a survey conducted in 1st through 5th grade classrooms in each country. Results show while the United States has by far the most uniform and comprehensive service, followed by Thailand with progressive services in their university demonstration schools. China and India, however, have little in place to assist struggling students in their highly populated classrooms.
Future wireless communication networks popularly known as beyond third generation (B3G) or Fourth generation (4G) networks will likely consist of heterogeneous wireless networks which will be IP-Centric based. These networks will offer a wide range of high data multimedia services to mobile users. To achieve this, Vertical Handoff (VHO) is considered as the method of realization and it is defined as the process by which users will seamlessly roam amongst these heterogeneous networks while communicating. To realize VHO, effective and efficient algorithms for accurate VHO decision are of utmost importance and hence form an area of current research focus. In this regards, several efforts have been made and it is the specific objective of this paper to provide an overview of efforts made thus far while discussing related VHO concepts. Specifically, handoff types, handoff process and classification of vertical handoff, metrics required, and existing works are presented. We seek to provide a concise background for not just VHO decision algorithms but also for understanding the basic concept of VHO.
Background: Despite the fact that essential oils are used as food and medicine, oils of rain forest plants remain largely uninvestigated. Aims: To investigate the physico-chemical properties and antimicrobial activities of essential oils from Hura crepitans, Xylopia aethiopica and Monodora myristica. Place and Duration of Study: This study was carried out in the Department of Microbiology, Ekiti State University, Ado-Ekiti, Nigeria between September, 2009 and January, 2010. Methodology: Standard methods were used to determine the physicochemical properties of the oils while antibacterial and antifungal properties were determined by agar well dilution and poisoned food assay respectively. Results: Hura crepitans had the highest acid value (9.8 mg KOH/g) and free fatty acids (12.15% oleic acid). Xylopia aethiopica had the highest activity against the test organisms while H. crepitans was the least effective on the fungal isolates. The oils were most effective against Salmonella typhi followed by Enterobacter sp. Pseudomonas aeruginosa showed the highest resistance to the essential oils. At 100mg/ml, the oils inhibited all the test bacteria with the diameter of zone of inhibition ranging from 6.0mm-17mm while the mean radial fungal growth was lower. The results indicate that essential oils are promising alternatives to standard antimicrobials. Conclusion: Xylopia aethiopica had relatively better antibacterial and antifungal activities; hence could be formulated in creams and ointments for the treatment of superficial infections and capsules for the treatment of gastrointestinal tract infections. However its toxicity requires further investigation.
The region of Pointe-Noire (south-west of Congo-Brazzaville) located on a coastal sedimentary basin of about 6 000 km2 is primarily formed by unconsolidated rocks with very little interstice porosity. It is made by a complex multi-aquifers system interconnected. Previous studies have highlighted the lack of data and the need to acquire a better knowledge of the groundwater resource in Pointe Noire. This study intends to represent and schematize the functions of the reservoir and the hydrodynamic behaviour of aquifer AQ-2. A Hydrogeological Information System (HIS) of aquifer AQ-2 is drawn up from historical reconstitution of the piezometric heads data carried out of various series of measurements from boreholes and piezometers .Two hydrological zones related to the topography and/or relief of study zone were identified: a zone of the littoral plain, characterized by protuberances and a strong depth of piezometric surface with hydraulic gradient of 0.03, revealing a flow of significant rate and an average permeability which represents a drainage weaker than the recharge; and a zone of the plateaux, characterized by a type of hydrogeologic structure called hydraulic threshold representing a fall of piezometric surface and hydraulic gradient (0.005 and 0.006), which can be explained by variations of flow rate or permeability. This morphology is imposed by two phenomena, the contribution of water of the plateau of Hinda on one hand and on the other hand, the general drainage direction revealed by the presence of the semipermeable facies.
This paper investigates the influence of diffusion annealing on some mechanical properties of 6063 aluminium alloy. Standard tensile and hardness test samples were subjected to diffusion annealing at 570ºC for 2, 2.5, 3 and 3.5 hours respectively prior to T6 tempering, another set of these samples were directly T6 tempered without prior diffusion annealing treatment. The two sets of samples were subjected to tensile and hardness tests and the evolving microstructure were characterized using Scanning Electron Microscope (SEM). Results indicated an increase in the mechanical properties for samples subjected to diffusion annealing prior to aging as compared to conventionally aged samples and there was also a remarkably good combination of mechanical properties especially percentage elongation (ductility) and yield strength. Samples treated by this technique find useful applications in the development of sustainable infrastructure in marine environments where other materials like 7075 aluminium or steel perform poorly as a result of ingress of chloride ion.
The effects of maleated polyisoprene (MAPI)/hexamethylene diamine (HMDA) dual compatibilizers and filler loading on physico-mechanical properties of natural rubber (NR)/poly(ethylene terephthalate) (PET)/dikanut shell powder (DSP) bio-composites have been investigated at filler loadings, 0 to 8 wt. %. NR/PET composition was fixed at 60/40 wt. %. Dikanut shell powder was prepared at three particle sizes of 120, 135, and 150 µm. The composites were prepared by reactive compatibilization in a two-roll mill. Results obtained have demonstrated that a combination of MAPI and HMDA is an excellent dual reactive compatibilizer for NR/PET/DSP bio-composites as shown by marked improvement in the properties investigated. The tensile strength, tensile elongation, unnotched impact strength, and melt flow rate of the composites were found to decrease with increase in filler loadings. On the other hand, the hardness of the composites increased with increases in filler loadings. However, the incorporation of MAPI/HMDA into the composites was found to improve these properties. Both the compatibilized and uncompatibilized composites absorbed water, the amount of which increased with increase in filler loading. The amount of water absorbed by the composites was substantially decreased on addition of MAPI/HMDA into the composites.
Aims: To determine the effects of cooking time on nutritional value of flours from yam “kponan” (Dioscorea cayenensis-rotundata) tubers. Study Design: Analysis of Variance (ANOVA) was employed in this work. Place and Duration of Study: Unité de Formation et de Recherche des Sciences et Technologies des Aliments (UFR-STA), Université Nangui Abrogoua, Abidjan, Côte d’Ivoire, during the period from June 2012 to July 2013. Methodology: Yam tubers were randomly harvested at maturity (6 months after planting) from three different farms. Yam tubers were washed, peeled, cut into pieces and cooked in boiling water at 100ºC, for periods of 0 min (FNT), 5 min (F5), 10 min (F10) and 15 min (F15). After cooling, the samples were cut, oven dried at 45ºC for 48 h, milled, sieved, packaged and stored at 4ºC. Standardized methods were adopted for proximate and functional properties evaluation of yam “kponan” flours. Results: Excepted the crude fat contents of flours, all the biochemical properties measured (dry matter, total ash, organic matters, total and reducing sugars, crude protein, carbohydrate) decreased significantly with the change in cooking time (p≤0.05). However, among functional properties studied, water absorption capacity, water solubility index and absorption capacity of some oils (palm oil, soybean oil, sunflower oil, red oil and olive oil) showed a significant (p≤0.05) increase with cooking time, whereas the foam capacity and stability of flours decreased significantly (p≤0.05). The flours exhibited different properties as showed by the Principal Component Analysis (PCA) that discriminated raw yam flour (FNT) from cooked yam flours after 5, 10 and 15 min (F5, F10 and F15, respectively). Conclusion: The use of cooking method in yam “kponan” flours processing appeared beneficial to improve their nutritional potentialities.
Aim: To investigate the effect of baking temperature on the quality characteristics of baked sweet potato crisp samples. Place and Duration of Study: Department of Food Technology, Federal Institute of Industrial Research, Oshodi, Lagos Nigeria, from February to October, 2013. Methodology: Yellow fleshed sweet potato were mashed upon cooking to form dough; and mixed with other baking ingredients. The developed dough was shaped and baked using five baking temperature levels (110ºC, 120ºC, 130ºC, 140ºC and 150ºC). The following analysis were carried out on the baked sweet potato crisp namely –proximate, textural and sensory analysis. The results obtained were statistically analyzed using Analysis of Variance and the means separated using Duncan Multiple Range Test (DMRT). Results: The result of the proximate analysis shows that moisture content ranged between 3.31 to 5.76 %, crude protein 2.61 to 3.22 %, fat 8.93 to 14.01%, crude fibre 2.59 to 4.79 %, ash 2.56 to 3.59 % and carbohydrate 71.56 to 78.15%. The result of the textural properties of the circular baked sweet potato crisps (dough thickness of 3.3mm and 30mm diameter) showed that the force at peak of the baked crisp samples ranged between 5.83 to 20.30 N, deformation at peak ranged between 1.33 and 2.22mm, while deformation at break ranged between 1.88 and 3.69mm. Sensory evaluation of the baked sweet potato crisps showed that crisp sample baked at 120ºC had the highest sensory rating of all the samples in terms of overall acceptability. Conclusion: The study revealed the possibility of producing crunchy baked sweet potato crisps using a baking temperature range not exceeding 140ºC. There is however need to strike a balance between the desirable sensory qualities and the textural properties to ensure product that would be acceptable to consumers.
The objective of this review paper, is the presentation of the basic features of the well known class of elliptic filters. Even though this is not a new subject, the theory of the elliptic filters found in most books is restricted only to a few resulting equations, due to the great complexity associated with the Jacobian elliptic functions. The aspects of the elliptic filters described in this paper include the detailed estimation of the minimum filter order, the construction of the filter transfer function via the identification of its poles and zeros in the complex plane, as well as the application of the resulting design procedure for the construction of an elliptic filter that meets prescribed specifications.