Vol. 12 Issue 2
Marouf A. Samhan and Fawzi A. Al-Thukair
In this paper we study fuzzy convex sublattice, fuzzy ideals (filters), fuzzy prime ideals, (filters) on a lattice and give a characterization of these concepts by their level sets. The fuzzy convex sublattices are represented in terms of fuzzy ideal and filters. Fuzzy maximal ideals (filters) are introduced, and in a special distributive lattices, the fuzzy maximal ideals (filters) are characterized in relation to fuzzy prime ideals (filters).
Hussein, M.T., Ibrahim, K.E. and Adam, E.G
The main purpose of this study was to compare hydrogeological and electrical properties of a consolidated sandstone aquifer. Transmissivity and hydraulic conductivity of the aquifer were determined at fourteen sites from controlled pumping and recovery well tests in Gedaref area, Eastern Sudan. Aquifer electrical resistivity, corrected transverse resistance and apparent formation factor were obtained from vertical electrical sounding measurements carried out at the same sites of the aquifer tests. Results of the study show a linear direct correlation between the transmissivity and the corrected transverse resistance. An indirect linear correlation was observed between hydraulic conductivity and apparent formation factor. The methodology adopted for this study can be applied to different areas but not the empirical relationships,
M.A.A.S. Alyan, Y.H.A. Rahim, and S.M.S. Al-Dhalaan
One most important aspect of design of superconducting generators concerns their stability following a major system disturbance. As the superconducting field winding of these generators has a relatively very long time constant, only governor control shall be relied upon to improve their stability. This paper presents the details of design of a state feedback controller, based on pole-placement technique, to improve transient performance of superconducting turbo-alternators, fitted with fast acting electro- hydraulic governors. The results, obtained by computer simulation, establish that such a controller, with a time delay to the control signal, enhances the transient stability of the machine, by rapidly damping the post fault rotor oscillation.
S.A.Kamh and F.A.S.Soliman
Tunnel diode is still regarded as a very useful device in R.F signal processing systems because of its wider band width, temperature stability and lower noise, compared with other diodes. Analytical and experimental investigations and computer program technique has been carried out to control the frequency, amplitude, waveform and output power for different types of tunnel diodes. It is found that the amplitude, frequency and shape of oscillations depend mainly on the biasing condition, and diode-and circuit-parameters. The frequency and amplitude increase with increasing the bias voltage , reaching a maximum value followed by a plateau region, then they decrease at high bias values, which reflects the limits of the dynamic negative conductance of the tunnel diodes. Results of the sinusoidal oscillations are obtained using InSb tunnel diode having the frequency value of 2.35 MHz. On the other hand, output waveform becomes approximately square wave in case of GaAs samples having the frequency of 0.80 MHz is obtained. The experimental results of the relaxation oscillator show good agreement with the predicted characterization based on the analytical solution and a computer program technique.
M.A. El.Demerdash and A.M. Zilay
Jizan region is located on the Red Sea coast in the South Western corner of Saudi Arabia. This region is situated in the tropical arid zone of the Arabian desert. Seventy stands, representing the physiographic and physiognomic variations in the area of study. were selected. From an ecological and geomorphological point of view , five distinct habitat types are recognizable in Tihamah coastal plains namely: shore-line , sand formations, salt marshes, wadis and rocky hills. A total of 153 plant species belonging to 46 families occupied the different habitat types of the Tihamah plains. Gramineae attaining 25. 7% of the total recorded species. The chamaephytes and therophytes life-forms are the most dominant life-form in the study area. Soil conditions, water availability, as well as, anthropogenic influences, playa leading role in the distribution of the various plant communities and their composition
M.A.Zahran, M.l. Soliman, M.S. Serag
.Juncus subulatus is a salt tolerant rush growing in the coastal and inland salt affected wetlands of Egypt. Its dense growth usually occurs in the wetlands associated with the northern deltaic lakes of Egypt.
The floristic composition and vegetative yield of Juncus subulatus community were studied in eight sites of the deltaic Mediterranean coastal bell of Egypt The associate species are mainly halophytes and helophytes. The means of moisture content, fresh weight and dry weight of June is subulatus culms were 70% 351 gm/m2 and 102 gm/m2 respectively. The anatomical studies show that these culms contain highly developed chlorenchyma issues and the sclerenchyma are absent except in the vascular bundles. Sclereides and calcium oxalate were not detected. This may explain that J. subulatus, unlike Juncus rigidus and Juncus acutus is not a fibre producing rush but it may be proposed as a fodder halophyte for domestic animals.
F.A. Al-Fassi, A.A. Malibari and M.A. Moustafa
Physiological studies were carried out on ten thermophilic and thermotolerant fungi isolated from the soil of different locations in Saudi Arabia. There were strong relationship between soil temperature, pH and salinity and the growth of the examined fungi. In order to obtain more information about the possible role played by these fungi in the soil fertility, their ability to produce amylase, casease and cellulase (Cx), in vitro were studied. All the fungi except Thermomyces lanuginosus, were able to produce enzymes. Thermomyces lanuginosus was unable to produce cellulase enzyme.
A.R. Hashem and Sarwat Parvez
Soil samples collected from Al-Zubira village of Hail region, Saudi Arabia, were screen for mycoflora and analyzed for mineral contents. The fungal genera isolated were Aspergillus (6 species), Alternaria and Fusarium (3 species each), Penicillium and Ulocladium (2 species each).
Artemisia monosperma, Calligonum polygonoides, Farsetia aegyptia and Zilla spinosa growing frequently in the same locality, were also collected and analyzed for heavy metals contents in the roots and shoots. Aluminium was found in high amount in all these plants and also in soil samples collected from Al-Zubira village followed by copper, lead and zinc.
Jumah Shakhanbeh
Blood flow in the rat skin was measured by laser Doppler flowmeter under normal conditions and after mild inflammation. Skin inflammation was induced either by a single subcutaneous injection (50 µl) of 2% carrageenan solution orby repeated topical treatment with chloroform over three days (once daily). In normal skin, the mean baseline blood flow is 57.7 ± 3.7 arbitrary units (n= 96), but has increased to 78.5 ± 8.7 arbitrary units (n = 48) in the carrageenan inflamed skin, and to 144.6 ± 16.9 arbitrary units (n = 48) in chloroform inflamed skin. Antidromic stimulation of the saphenous nerve (0.2 - 5.0 mA, 0.5 ms, 1 Hz) for 10 seconds has increased the blood flow in normal skin to 77.3 ± 9.0% (n = 25), and in carrageenan inflamed skin to 104.8 ± 9.6% (n = 57). The results show that the cutaneous neurovascular responses are elevated under the conditions of acute inflammation.
Mohammed S. Al-Yousif and Hussein S. Hussein
Skin snipping of the head and neck regions of live Arabian camels (Camelus dromedarius) in the Central Region (Riyadh and Qasim Provinces) of Saudi Arabia and the release of Onchocerca species microfilariae (mff) into 80% Tyrode's solution with 20% camel serum and antibiotics have been used to estimate the prevalence of camel onchocerciasis in this region. The study has also been complemented by skin snipping of camels to be slaughtered for human consumption at Riyadh Central abattoir and at Buraydah abattoir during ante-mortem examination and by post-mortem examination of carcasses of the same camels for adult Onchocerca worms. Onchocerca fasciata is the only species detected with an overall prevalence rate of 59.1% which is corrected to 77.2% by the elimination from the sample of young and old camels that do not have mff in their snips. The prevalence of infection is higher in camels in Qasim Province (65% for all camels samples and 84.3% when corrected by removing young and old camels with no skin mff) than in those in Riyadh Province (56% and 73.4%, respectively). However, camels in the agricultural parts of both provinces show the highest rate of onchocerciasis and those in the drier western parts of Riyadh Province (Al-Dawadmi and Afif) are the least infected. Sedentary camels in farms have the highest prevalence of infection and the highest density of skin mff than free-ranging nomadic camels. This has been discussed in accordance with the suitability of breeding habitats of supposed vectors (possibly midges of the genus Culicoides) in and around farms than anywhere else. Both sexes are equally infected and the infection is chronic, non-seasonal and results in no overt clinical disease, but increases with the age of the animal (older camels are more infected than young ones). Onchocerca fasciata has a predilection to the ligamentum nuchae where infections seem to start and thereafter, spread to other locations, especially subcutaneously in the regions of the flanks before becoming generalized in old camels. No pathological conditions have been observed in association with mff in the skin of infected camesl, but the general host reaction to adult worms consists of non-suppurative worm granuloma formation, but with far less degree of fibrosis and cellular reaction than in any other Onchocerca infection.