nigerian defence academy
journal of science and engineering (ajse)
APPLICATION OF A METHOD OF MESUREMENT OF GROUND CURRENTS TO RADIATED ELECTROMAGNETIC EMISSION TESTING
A method of radiation electromagnetic emission testing that relies on measurement of ground currents induced by the emission on a conducting ground plane is presented. The principle of the method is explained and comparison of the method is made with the standard method of radiated emission testing that is the “open area testing”. The advantages and disadvantages of the method are explained and results of practical application of the method to assess the emission from equipment under test are presented..
COMPRESSION BEHAVIOUR OF INTERWOVEN SANDCRETE BLOCK MANSORY
AA ADEDEJI and S P EJEH
Most masonry design codes consider only the sandcrete block masonry with mortar joint, while mortarless joints are yet to be incorporated in the design for the interwoven Sandcrete Block Masonry (ISB).In this work , the strength test s and results under axial and eccentric load indicate that, decrease in the masonry capacity is as a results of large eccentricity of load with a high degree of deflection. Compressive strength is higher than that of conventional sandcrete with a factor of 1.06. The ratio of masonry strength to its unit, an important factor in the preliminary design, is 0.83. This is higher than that of conventional masonry-unit strength ratio of 0.34 even though, factor of safety for material compensates for the excessive masonry strength by interpolation for the characteristic strength in the case of conventional masonry. The strength interpolation is overcome by a working graph prepared for any required ISB-block strength.
SYNTHESIS AND STUDIES OF CHELATE COMLEXES FROM INDIUM(III) CHLORIDE AND TIN (II) CHLORIDE DIHYDRATE
D. T. KUKWA
Complexing reactions of the chlorides of Indium (III) and Tin with Alizarin red-s and the nitrogenous organic compounds of cuferron, 1,10-phenanthroline and ethlenediamine are reported. All reactions were effected in ethanol. 1,10-phenanthroline and ethlenediamine gave instant solid products. Cupferron gave an instant colour change with crystals separating out only after about 2-14 days. Alizarin red-s did not give any crystals with Tin (II), but gave crystals with Indium (III) after 7 days. Absorption spectral analysis of Alizarin red-s-Indium (III), Tin (II) complexes showed λmax at 450 nm for Tin (II) and a shift from 425 nm to 516 nm for Indium (III).
A SURVEY OF THE FISHING GEARS AND CRAFTS USED BY
ARTISANAL FISHERMEN ALONG RIVER KADUNA
A study of the fishing gears and crafts employed by artisanal fishermen along river Kaduna was made. The gears included lines, wounding gears, traps, nets, fences and shelters while crafts included calabash, and dugout canoes. Cast nets and gills nets were found to be most effective and productive among the gears while planked canoes were the most commonly used for mobility. The low literacy level among the fishermen was found in influence their choice of gears and crafts.
NORMALIZING OF MONTLY AND WEEKLY RAIN FALL
SERIES FOR KANO, KANO STATE, NIGERIA
FOLORUNSHO J.O. and ATI, O.F.
Monthly and Weekly rainfall series for Kano in Kano State were subjected to the normality test using standardized coefficient of skewness and kurtosis. Both series were found to be non-normal at 0.05 or 95% confidence limit. The data were therefore subjected to the Cube Root Normal transformation model, and the Modified SMEMAX transformation model, though there are other models. The modified SMEMAX model was found to be simpler and of a greater transformation power of skewness for all manual purposes.
DETERMINATION OF TRACE ELEMENT CONCENTRATIONS IN NIGERIAN ROCKS
BY K-FACTOR INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS
M.C. MAYAKI AND I.O.B. EWA
The use of multi-elemental methods for the determination of trace elements is well known. Alternative methods like the relative as well as the absolute methods in Neutron Activation Analysis (NAA) could be time consuming and labour intensive. We report another technique termed the single-comparator standardization method for instrumental NAA Experimentally determined k-factors obtained for each of the elements of interest using the Research Reactor of the institute of Nuclear Techniques, Technical University of Budapest, were used for the evaluation of 24 trace elements including nine Rare Earth elements from Itakpe Iron, Mfamasong Limestone, Illo-Quartz Mica, Osaro-Dolomite and Isanlu-Talc. Standardization was achieved by the use of Gold as the comparator element, while the thermal neutron flux was maintained at 2 x 1012 n cm2 s-1 and monitor with the use of Zirconium foils. Our results showed good values much better than 2%, with a high concentration of Iron (38.9%) for Itakpe Iron, as well as high value for Tungsten in both Itakpe Iron and Illo-quartz (606ppm).
ASSESSMENT OF KADUNA TOWNSHIP ROAD NETWORK AND ITS
CONTRIBUTION TO TRAFFIC CONGESTION
ABSTRACTThe study deals with the assessment of road network in Kaduna Township with a view to proposing solutions to its incessant traffic congestion. Data for the study are generated from aerial photographic of 1987 and 1993 at scale of 1:10,000 with supporting information from topographic maps, land use maps and fieldwork. The technique for the analysis of the road planning indices to assess the quality of road network are the simultaneous use of cyclomatic number, beta index, alpha index and gamma index. The results in the order of the road planning indices given are expressway network (7, 1.40, 28%, 54%), expressway and major arterial network (52, 1.63, 33%, 56%) while the combination of expressway, major arterial and collectors network has (232, 1.32, 16%, 44%). These results reveal that the existing road network is poorly connected and not adequately dense. Consequently, it is partly responsible for the current road traffic congestion within the township.
DEVELOPMENT OF A FEASIBLE METHOD OF DRILLING
DEEP GUN HOLES ON THE ENGINE LATHE
The barrel is the most important part of the gun that determines the desire characteristic performance of fired projectiles. It is for this reason that gun barrel have to be produced to stringent design specifications. Conventional drilling of deep holes to produce some gun barrels is attended with difficulty in achieving the high accuracy requirements of designed gun holes. This difficulty is exacerbated by the fact that : the workpiece and drill have to be long or slender during a drilling operation, thus making them more prone to elastic deflection and vibration adversities as well as tendency towards instability and or buckling; higher temperatures are developed with possible tool softening or deterioration; chip removal and application of coolants become more difficult as the depth of the hole increases: etc. In arms manufacturing and other related industries, these are surmounted and high-quality deep gun holes are produced faster and efficiently, by using special-purpose automated machine tools equipped with elaborate facilities. In this paper, a feasible, economical, and applicable methods of drilling good- quality deep gun holes in general-purpose machine shops, where such special drilling equipment are lacking is elaborated. The paper is a contribution towards adaptation of common facilities for authorized, job-lot production of some arms locally, to meet necessities as well as other technical areas that require application of similar deep holes.
NUMERICAL ANALYSIS OF NATURAL CONVECTION INDUCED IN A POROUS
TRIANGULAR DOMAIN WITH INTERNAL HEAT GENERATION
The induced free convection from along horizontal triangular domain with internal heat generation is presented here. The numerical simulation using a numerical scheme by the Gauss Stedel method of successful displacement are conducted in the range Ra = 0, 10 - 000, S = 0.0 – 10.0 and H/L = 0.2-1.0, where ‘R’a is Rayleigh number, ‘S’ is the internal heat generation, and ‘HlL’ is the height to base ratio otherwise known as the Aspect Ratios (ASPR). The results have shown that the presence of internal heat generation changed the pattern obtained between the average Nusselt number and the Aspect Ratio. The average Nusselt number is found to increase with increase in Aspect Ratio. Convection is more pronounced at high value of Rayleigh number and Aspect Ratio and increases with the value of the internal heat generation. It was also found that the heat transfer on the cold wall increased toward the intersection of the hypothenus and the base wall.
THE ACCURACY OF SURVEY CONTROLS EXTENDED THROUGH AERIAL TRIANGULATION BY INDEPENDENT MODEL METHOD
This examination of the systematic error incurred in the extension of survey control through aerial triangulation by independent model method is prompted by the fact that in any survey control extension be it photogrammetry or conventional land surveying method, error will always occur, which could be systematic, compensating or gross error. A stepwice error analysis shows a linear misclosure of 0.08115m, which translates to an accuracy of 1/350,000 for horizontal co-ordinate and an error of 2.015m for vertical co-ordinate that grossly exceed the permissible error of 11.97mm and 23.93mm respectively for both precise and ordinary site survey . Based on these result, it is recommended that this method of survey extension may be used for control extension for horizontal co-ordinates. However, where higher accuracy of vertical control is required, it is recommended that the method should be de-emphasized.
AN ASSESSMENT OF THE WIDEBAND PERFORMANCE OF COAXIAL TRANSMISSION LINE IMPEDANCE TRANSFORMERS
U. G. DANBATTA
A tuned half -wavelength dipole is a balanced antenna that has an approximate input impedance of 55 - 65Ω, depending on the frequency and diameter of the dipole elements. Current-balancing and impedance-transformation device are therefore necessary to present a matched load to the transmission line connecting the dipole antenna to a 50-Ω source or receiver, over a wide frequency range on which the dipole antenna is intended to be used. The analysis, design and testing of such devices over the frequency range of 20 – 1000 MHz are presented. Calculated and measured results obtained from frequency response test show that the device have excellent symmetry and a pass-band loss that does not exceed 2 dB.
ACTUAL LEAD (Pb) CONTENT OF KUBANNI DAN, SAMARU, ZARIA
MUHAMMADU LAWAL GARBA AND KRZYSZTOF SCHOENEICH
A re- assessment of lead (Pb) concentration in kubanni dam, Zaria was carried out. Findings from both kubanni dam and areas within its drainage basin which are considered by the Authors as non polluted, indicate a Pb concentration in the rage of <0.024ppm to <0.011ppm for kubanni dam, and from <0.008ppm Pb for areas considered as non polluted.
QUALITY OF TREATED WASTEWATER EFFLUENTS FROM SELECTED INDUSTRIAL SOURCES IN IKEJA, LAGOS.
B.F. SULE AND M.U. OGUM
Wastewater samples were collected from effluents of treated plants in four industries located in the Ikeja Industrial Area of Lagos State. The samples were analysed to determine the physical and chemical constituents. The results were compared with effluents standard, recommended by the Federal Environmental Protection Agency (FEPA).The results showed that the plants were operating at efficiencies ranging from 52 to 91%. The effluents from two of the four industries contained substances with concentrations which were well above the limits, while effluents of two other industries were satisfactory. It is recommended that the regulatory agency should monitor discharges in all industries and ensure compliance with standards in order to reduce the hazardous effect on the environments.
STUDIES ON THE CHEMICAL CONTROL OF AQUATIC WEEDS: 1. EFFECT OF 2,4 -DICHLOROPHENOXY ACETIC ACID AND MELEIC HYDRAZIDE ON GROWTH AND NUTRIENT STATUS OF WATER LETTUCE (Pistia stratiotes).
S.P. BAKO AND H.S. UMAR
A study was conducted (in a closed culture system) to evaluate the effect of using two chemical compounds, 2,4 – Dichlorophenoxy acetic acid (2,4-D) and Maleic Hydrazide (MH) on the growth and nutrient status of the water lettuce (Pistia stratiotes) in Zaria, Nigeria. Vegetative growth rate of between 2.92 -5.41g fr. Wt. day-1 was recorded for this weed, leading to biomass (fresh weight) increases of between 135.15 – 244.87% over a culture period of 45 days. Application of 2,4-D (at 8g sq m-1) significantly (P = 0.05) depressed the growth of (Pistia stratiotes) while MH (at 8g sq m-1) first had a stimulatory effect before growth depression became apparent. Soluble carbohydrate status (% glucose) generally declined in response to 2,4-D application, while on application of MH, an increase was noticed before a decline. Crude protein content (% N x 6.25) increased slightly in response to 2,4-D treatment. On the other hand a temporary decline preceded slight increase, when MH was applied. Results are discussed in relation to the effect of these chemicals on the physiology and growth of plants and how the chemicals can be used for an environmentally safe management of aquatic weed problems in lentic fisheries systems in Nigeria.
STUDIES ON THE CHEMICAL CONTROL OF AQUATIC WEEDS: 2. EFFECT OF
2,4 - DICHLOROPHENOXY ACETIC ACID AND MELEIC HYDRAZIDE ON GROWTH AND NUTRIENT STATUS OF THE AQUATIC FERN (Salvinia nymphelulla)
S.P. BAKO* AND H.S. UMAR
A closed culture system study was conducted to evaluate the effect of using two chemical compounds, 2,4 – Dichlorophenoxy acetic acid (2,4-D) and Maleic Hydrazide (MH) on the growth and nutrient status of the aquatic fern (Salvinia nymphelulla) in Zaria, Nigeria. Vegetative growth rate of between 5.06 -5.24g fr. Wt. day-1 was recorded for this weed, leading to biomass (fresh weight) increases of between 1225.27 – 1354.02% over a culture period of 45 days. Application of both 2,4-D and MH (at 8g sq m-1) significantly (P = 0.05) depressed the growth of the plant. Soluble carbohydrate (% glucose) status of plants treated with both 2,4-D and MH increased sharply, before a final decline. Crude protein content (% N x 6.25) generally increased in response to treatment with both chemicals. Results are discussed in relation to the effects of these chemicals on the physiology and growth of plants and how the chemicals can be used for an environmentally safe management of aquatic weed problems in lentic fisheries systems in Nigeria.
AN APPRAISAL OF TWO-DECADES OF EXISTENCE OF
UNIVERSITIES OF TECHNOLOGY IN NIGERIA
Nigeria presently has the highest rate of growth of higher Institution in the whole of black world [I]. Equally, the fund allocated to Federal Universities has risen from N621,.65 Million in 1981 to N26,669 Million in the year 2000. However, the quality of graduates of the Nation’s Universities of Technology, two decades after inception, is falling drastically. This paper attempts to appraise the growth in number, enrolment and funding of these specialized institutions alongside the conventional ones in the last two decades. Reasons were proffered for the falling standard of training in these institutions and suggestions were made for charting a new course for the Nation’s engineering education.
HEAVY METAL CONCENTRATIONS IN SOME TROPICAL MUSHROOMS
Mayaki M.C. , Oladipo, M.O.A., and Kadiri, M.
Three Nigerian mushroom types, namely cortinarious mellionlens fries, Chlorophyllum molybditis (Mayer ex. Fr.) Massee and Termitomyces robustus (Beeli)Heim were analyzed for Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, and Pb. The elemental concentrations ere determined using the x-ray fluorescence (XRF) technique. The significance of the present findings is discussed in relation to human nutritional requirements for trace elements (essential elements) and toxic element concentrations and thus the edibility of the mushrooms.
EFFECTS OF TWO-STEP DEPOSTION ON CURRENT TRANSPORT IN
AL-GE-AU SANDWICH STRUCTURES
M.G. Zebaze Kana, R.K. Odunaike & A.A. Oberafo
Investigations have been carried out at temperatures between 123 and 300K on as-deposited, vacuum evaporated Al-Ge-Au sandwich structure samples fabricated on Al support discs. The sandwiched, evaporated Ge layers were vacuum-deposited in either one or two steps of various thickness, while the Al and Au contact on either side where each vacuum that deposited in one step. Furthermore, for the two-steps Ge depositions, the first Ge layer was exposed to air at room temperature for an hour before the second layer was deposited. All the samples showed good ohmic behaviour. The specific resistance (Rs) of the Al – Ge – Au layers increased as the thickness of the sandwiched Ge layer increased, but decreased as the temperature increased. The dependence of Rs on the temperature of the course indicated semiconducting behaviour in the Ge layer. It was also found that for a given overall thickness, Rs increased as the number of steps increased, while there was no significant change in Rs for samples of some overall Ge thickness deposited in the same number of steps.