Digital Repository for University of Tripoli

Abstract

Ad-hoc networking is a concept in computer communications, which means that users wanting to communicate with each other form a temporary network, without any form of centralized administration. Each node participating in the network acts both as host and a router and must therefore be willing to forward packets for other nodes.In a multi-hop wireless packet network, a packet traverses more than one wireless link in traveling from its source to its destination. Such wireless networks have received considerable attention recently in the context of ad hoc networks. Ad-Hoc networks are self-organizing multi-hop wireless networks where not all links along the path of a packet can be activated simultaneously. Hence the performance of a higher level mechanism, such as congestion window or Transport Layer protocol (TCP) will depend crucially on how the links are scheduled for transmission. In multiple access networks, such as the IEEE802.11 wireless LAN, the scheduling of transmissions is done by the medium access control (MAC) protocol. This transmission scheduling is completely unaware of the needs of the TCP congestion window protocol. This thesis is concerned with the poor interaction between the TCP adaptive window protocol, the IEEE 802.11 MAC protocol, and the IEEE 802.11 Ad-Hoc routing protocol. Our thesis follow on the work done by the researchers K. Nahm and C. Kuo in the paper entitled “TCP over 802.11 Multihop networks issues and Performance Enhancement” [1]. Our contributions are two-fold. First we have repeated and confirmed the simulation results reported by K.Nahm and C.Kuo using NS-2 network simulator. Second we have introduced a simple modification in the 802.11 DSR routing protocol which reduces the unnecessary VI reroutings triggered by MAC packet collisions and enforces the TCP to enter the fast retransmit / fast recovery phase to quickly recover the packet loses. This modification has been simulated using NS-2 network simulator and from the results we have found that it provides a substantial improvement in TCP performance in the situations that we have considered in the simulation models
يحي الشارف المبروك (2009)

Abstract

Against the background due to the energy crisis in the late 1970’s, the pinch analysis has emerged as a powerful tool for the integrated design of process heat networks which include heat exchangers, distillation columns, furnaces, etc..The key strategy of this methodology is to set energy targets prior to design based on basic thermodynamic principles.The subject of this thesis in to apply this analysis to one of the Libyan Refineries, namely Ras Lanuf Refinery, to assess energy utilization of such big energy – consuming plants and to explore the potential of energy as well as capital costs savings based on the finding of applying this analysis. Based on actual operating data collected from the plant and application of the procedure of the pinch analysis to this real case study where a minimum temperature difference approach in the Ras Lanuf refinery heat exchangers design of 10 (ΔT min =10 ) the following results were obtained. Actual rate of energy consumption of the base case design of the refinery is 9MW which is provided by burning fuel oil in the furnace, while the minimum target predicted by the pinch analysis should be 8MW. This amounts to just over 11% energy savings which equivalent to $462,000 per year reduction in the operating cost of the refinery
هويدة الهادي الحبيشي (2011)

Abstract

As part of the NE-trending Mourizidie Shear Zone in south-central Libya (south of Mourizidie pass), four units representing Preccambrian basement rocks (metasediments) were mapped during field work: phyllites (metaclaystone); metapelites (metasiltstone); pasmmites (metasandstone) and Quartzites. Granitic bodies of various sizes (few meters to hundreds of meters) are found throughout the study area. The metasediments and granites are both intruded by veins and dikes having an overall NE trend. Four Palaeozoic sedimentary units were mapped within the study area. The concidence of the S1 foliation with the S0 of the original bedding of the protolith is a proof that the S1 foliation is caused by deep burial. The petrographic description of the minerals in thin section shows an assemblage of sericite, muscovite and biotite, all representing a sub-greenschist facies to greenshcist facies. This low grade metamorphism helped in preseving the original sedimentary structures of the protolith, thus helping in identifying the original bedding plane S0. Faults observed in the field or traced on aerial photograhs belong to three major trend: NE, NNE, and ENE. Folds are extremely diverse in shape, attiude and tightness, thus their classification is equally diverse. This diversity is observed in the field even within a distance of no more than few meters. The isostatic rebound of the basement could have caused this great difference in the attitude of the folds, especially at considerable depths characterised by a kinematically ductile, restricted and contained settingAt least two phases of deformation are present in the area. D1 is marked by the generation of S1, while D2 is marked by the first folding F1 caused by the isostatic rebound he generation of S2 foliation as fan cleavage is directly related to the F1 folding. Some folds underwent refolding, which lead to an F2 phase of folding.Sequential schematic structural model is proposed to explain the structural history of the study area. This model should be tested through intensive detailed field work large scale map in nearby areas.
مسعودة محمد حنبولة (2015)

Abstract

Benzodiazepines are frequently prescribed as anxiolytics, sedatives hypnotics, and muscle relaxants as well as anticonvulsants. Non-steroidal anti-inflammatory drugs (NSAIDs) are also the most widely used for their anti-inflammatory, analgesic and antipyretic activities. Because of the chronic nature of epilepsy, NSAIDs may be used with benzodiazepines in patients with epilepsy. Therefore, there’s a probability of an interaction of NSAIDs and benzodiazepines in clinical practice. In order to study such interactions experimentally, an animal model was used. Thus, this thesis was aimed to explore pharmacological interactions between selective and non selective NSAIDs and diazepam anticonvulsant effect. Convulsion was induced in male albino mice by picrotoxin in two different doses (6 and 8 mg/kg), NSAIDs were used according to selectivity to cyclooxygenase enzyme (COX): Aspirin at 10 mg/kg (COX-1 selective inhibitor) and Aspirin at 100 and 200 mg/kg, diclofenac 10 and 20 mg/kg (non selective COX inhibitors) and celecoxib 20 mg/kg (COX-2 selective inhibitor). Diazepam at 1 and 2 mg/kg were chosen as low doses and parameters of convulsive behavior of picrotoxin deviation. psy, NSAIDs may be used with benzodiazepines in patients with epilepsy. Therefore, there’s a probability of an interaction of NSAIDs and benzodiazepines in clinical practice. In order to study such interactions experimentally, an animal model was used. Thus, this thesis was aimed to explore pharmacological interactions between selective and non selective NSAIDs and diazepam anticonvulsant effect. Convulsion was induced in male albino mice by picrotoxin in two different doses (6 and 8 mg/kg), NSAIDs were used according to selectivity to cyclooxygenase enzyme (COX): Aspirin at 10 mg/kg (COX-1 selective inhibitor) and Aspirin at 100 and 200 mg/kg, diclofenac 10 and 20 mg/kg (non selective COX inhibitors) and celecoxib 20 mg/kg (COX-2 selective inhibitor). Diazepam at 1 and 2 mg/kg were chosen as low doses and parameters of convulsive behavior of picrotoxin were observed in this thesis: onset time, episode frequency and death occurrence within post-injection of picrotoxin for 24 hrs. Aspirin in low dose (10 mg/kg) showed protection against death to about 50%. This protection which seems to be partially effective as anticonvulsant agent, however, higher dose of Aspirin (100 mg/kg) did not produce any significant change against convulsing in mice, Aspirin 200 mg/kg showed highly significant reduction of episode frequency (P < 0.001) and decreased percent of death. Furthermore, Aspirin 200 mg/kg in combination with diazepam has potentiated the effect of diazepam to complete protection against convulsion induced by picrotoxin. With respect to diclofenac, diclofenac pretreated-mice did not show any significant effect at 10 and 20 mg/kg with picrotoxin but in combination with diazepam showed significant potentiated effect of diazepam. Moreover, COX-2 inhibitor (celecoxib) alone delayed onset of convulsion without significant influence against the control but significantly decreased episodes and percent of death. Also in combination of celecoxib and diazepam, a highly potentiation of the effect and almost complete protection against convulsion behavior were noted (P < 0.001). Thus, it can be concluded that the studied NSAIDs have anticonvulsant behavior-like activity alone and in combination with diazepam. The most profound effect of anticonvulsant activity was showed in low episodes and mortality rate. In combination with diazepam, NSAIDs have more positive potential role in diazepam anticonvulsant effect. The present findings may also suggest that NSAIDs most likely COX-2 selective inhibitor is more potentiated diazepam’s anticonvulsant activity than COX-1 selective and non-selective inhibitors and such interaction could be more likely to be pharmacodynmic type.
نجمية محمد الزواوي (2014)

Abstract

Biocides (disinfectants and antiseptics) are used extensively in hospitals and other health care settings for a variety of applications. However, their antibacterial effectiveness is not always well stated by the manufacturers and consumers find it difficult to choose the right product according to their needs. Therefore, the aim of this study was to evaluate practically achieves disinfection efficacy of locally available disinfectants and antiseptics on surfaces and infectious microbiological utilities of Tripoli Medical Center (TMC). Fourteen biocides; Ten disinfectants (Dex36, Dex50, Dex53, Mzid-S, Mzid-AF, Deson, Dettol, Seem, Chlor and Wipol) and four antiseptics (HiBi, Esept, Emed and Desman) were tested at concentrations recommended by manufacturers on surfaces, walls and different utilities that were contaminated by locally circulating six isolates of Bacillus cereus, Staphylococcus haemolyticus, staphylococcus aureus, Klebscilla pneumonia, Acinetobacter baumannii, and Pseudomonas aeruginosa using four standard evaluation test procedures (capacity test, diffusion test, in-use test and suspension test). Results showed the highest average log reduction (7.4) of test bacteria was given by quaternary ammonium based disinfectants; Dex50, Dex53, Deson-AF and Mzid-S. A comparable average log reduction of test bacteria was noted (7.0, 7.2 and 7.3) for Deson-AF, Dex.50 and Dex.53 respectively. In contrast HiBi as an alcoholic based antiseptic gave the highest average log reduction (7.2) against tested bacteria. Desman, Emed and Wipol antiseptics had poor antibacterial activity on tested bacteria causing almost undetectable log reduction in cell viability. From contamination point of view, five critical departments in Tripoli Medical Centre (TMC) namely; Neonatal Intensive Care Unit (ICU), Surgical ICU, Dermatology, Oncology, and Urology departments were found contaminated with six types of bacteria. Bacillus cereuses followed by Klebscilla pneumonia were the most bacteria spread in whole five mentioned departments, particularly in dermatology department. Staphylococcus haemolyticus was next most widespread bacterium and almost isolated equally from the five medical departments. Acinetobacter baumannii had been isolated from Neonatal ICU; whereas Staphylococcus aureus and Pseudomonas aeruginosa had been isolated from Oncology Department and Surgical ICU respectively. In addition, Dex36, Chlor, Chlor, Wipol, Desman and E-med exhibited bacterial contamination in both capacity and in-use tests. In conclusions, quaternary ammonium compounds (QACs) and combination of QACs with aldehyde formulations were found to be the best disinfectants for disinfection of contaminated surfaces.
عتيقة صالح الهادي (2016)

Abstract

Biological studies of Nezara viridula (L.) (Heteroptera:Pentatomidae) and its parasitoid Trissolcus basalis (Wollaston)(Scelionidae: Hymenoptera) collected from Libya were conducted in a rearing room at 25 ± 5°C, 65 ± 10 % R.H. and 16:8 LD photoperiod.During the course of rearing of N. viridula the eggs incubation periodvaried between 4-7 days. The newly emerged nymphs and the 5th stage had the highest mortality in comparison with 1st, 2nd, 3rd and 4thstages .studies on T. basalis included: SEM, development time, parasitoid mating behavior and oviposition behavior, functionalresponse and fecundity. The development time was 4 to 10 days underthe laboratory condition. Adult males lived longer than females.Mating time took from 12.2 to 19.5 seconds. In case of ovipositionbehavior serial of behaviors were observed and recorded. The egg selection period was 0: 00: 08 - 0: 00: 25 min, oviposition period was 0: 01: 04 - 0: 01: 41 min. Egg marking period was 0: 00: 11 - 0: 00: 25 min. The longest period was the oviposition period followed by egg marking period followed by egg selection period.In functional response study was found a highly positive correlation ( r = 0.974 ) number of egg masses exposed and the number of parasitoid emerged. Fecundity experiments showed that the daily ii production of progeny by female of T. basalis during 6-10 dayslifetime showed that female progeny production was higher than male progeny production. The maximum period offspring production was 6-10 days. There was a highly negative correlation ( r = - 0.900 ) between the number of eggs parasitized and parasitoid age . Also there is a highly signifcant difference between the fecundity of T. basalis newly emerged of 24 h and after 7 days after emergence from N. viridula eggs. The number of mature eggs in the ovary were less in 24h aged female and the fecundity increased over the next 7 days.
عايدة عادل عبد الرحيم بادي (2008)

Abstract

Cement kiln dust is a major by product in cement manufacture. Methods of disposal, handling, treatment and reuses are a major factors in optimization of a certain cement plant. This thesis concentrates on the uses of cement kiln dust of souk Al Kamees cement plant as Soil amendment and as an adsorpent of Fe, Zn and lead results from sand. The major objectives of these treatments are environmental rather than economical to reduce the landfill disposal of CKD which is major problem in cement industry. CKD is used in agricultural soil amendment.CKD in Souk Alkamees consists primarily of calcium carbonate and silence dioxide, the alkaline by pass process contains highest amount of calcium oxide and lowest loss on ignation [LOI] which become a beneficial for CKD use as a soil amendment to the sand for many especial agricultural products such as potatoes, …etc. This thesis concentrates on the uses of CKD as an adsorbent to remove heavy metals such as Fe, Zn, and Pb from soil. Adsorption column is used to perform the work. Experimental setup discussed in the thesis is used using cement kiln dust as an adsorbent for removal of heavy metals from soil. The major result is to simulate the physical behavior of the process using conventional isotherms available in literature, Langmuir, Freandlish and Drachsal isotherm models have been found to simulate the data with good agreement with experimental work. Characterization of the CKD is made after dehydration process at 150C for 24 hrs. X ray fluorescent equipment is used and the results are reported in the thesis.
محمد محمود الشاهري (2015)

Abstract

Copper and copper – base alloys are widely used for numerous applications demanding good mechanical properties , resistance to corrosion , good electrical onductivity (EC) , pleasing colour and ease of fabrication [1,2] . Among the alloys having a good combination of high strength and high thermal as well as electrical conductivity, age hardenable Cu-Be alloys are most widly used but they have the limitation of toxicity and high cost of production. Cu- Ti binary alloys are precipitation strengthened by spinodal decomposition mechanism [3-5] involving composition modulations and long range ordering in the initial stages of aging. The tensile strength value of 930N/mm2 was obtained for Cu-5.4wt%Ti alloy by the precipitation of a coherent and metastable fine precipitate of Cu4Ti (β`) and electrical conductivity of 24.5%IACS was obtained for Cu-1.5wt%Ti alloy on peak aging [6]. Experiments on cold compression followed by aging of Cu-Ti alloys have indicated that the most effective hardening of the matertial results from continuous precipitation of very fine particles within the matrix. These particles were reported to be β` -type, Cu4Ti phase. The β`-β transformation and particles coarsening within the matrix as well as a long grain boundaries were responsible for the overaging of Cu-1.5wt%Ti and Cu-3.5wt%Ti alloys It is well know that plate like particles are β – type, Cu3Ti phase. Discontinuous precipitation was found to start at the grain boundaries and expand into grain interior. At the higher aging temperature a classic widmanstätten morphology forms giving rise to a coarse microstructure comprised of α and the equilibrium phase β. Those results were confirmed by X-ray analysis, which found that a few percent of Cu3Ti, β precipitates are formed during aging at high temperature for long time for both Cu- Ti alloys (i.e. Cu-1.5wt%Ti and Cu-3.5wt%Ti).
مريم محمد مرغم (2008)