Academy of Graduate Studies
Tripoli, Libya

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Alsahdi U.,Academy of Graduate Studies
ICCTD 2010 - 2010 2nd International Conference on Computer Technology and Development, Proceedings | Year: 2010

This paper proposes a cryptosystem (encrypting/decryption) for XML data using RSA (Rivest, Shamir, and Adleman) with some form of shift ciphering scheme. Such a system is designed to achieve some of security aspects such as confidentiality, authentication, and integrity, and non-repudiation. We used XML data as an experimental work. The implementation is done using VB.NET. Since, we have used RSA with some padding scheme; it is extremely difficult to factor large numbers. The property of shift ciphering scheme increases the cost of cryptoanalysis. The results are very much satisfactory for securing XML data. We found the estimation required time to break our generated keys is 3128 years, which is sufficient against any brute-force attacks. © 2010 IEEE.

Edreder E.A.,Libyan Petroleum Institute | Mujtaba I.M.,University of Bradford | Emtir M.M.,Academy of Graduate Studies
Chemical Engineering Transactions | Year: 2012

The middle vessel column (MVC) is a combination of a batch rectifier (conventional column) and a batch stripper (inverted column). Therefore it is possible to obtain a light and a heavy fraction simultaneously from the top and the bottom of the column while an intermediate fraction may also be recovered in the middle vessel. Several researchers in the past have proposed the esterification of lactic acid (impure) with alcohol to obtain lactate ester which is then separated by distillation. To the best of our knowledge, simulation of middle vessel batch reactive distillation column for hydrolysis system has not yet been explored. In this work, the hydrolysis reaction of methyl lactate to produce lactic acid (LA) is carried out in a middle vessel column with fixed batch time while control variables are treated as a piecewise constant reflux ratio (multiple time intervals) and a single reboil ratio. For MVC, the LA being the heaviest in the reaction mixture, reflux and reboil ratios policy plays an important role to achieve high purity of LA. Copyright © 2012, AIDIC Servizi S.r.l.

Edreder E.A.,Libyan Petroleum Institute | Mujtaba I.M.,University of Bradford | Emtir M.,Academy of Graduate Studies
Chemical Engineering Journal | Year: 2011

Hydrolysis of methyl lactate to lactic acid in a reactive distillation column is widely used in the purification of lactic acid. In this work, optimal operations of conventional and inverted batch reactive distillation columns undergoing the hydrolysis reaction are presented. Minimum time optimisation problem is formulated incorporating a process model within gPROMS software and is solved for different range of lactic acid purity and the amount of product using both columns. For a given column type and configuration the minimum operation time is obtained by optimising the reflux ratio profile. For conventional column, the lactic acid being the heaviest in the reaction mixture, reflux ratio policy plays an important role in removing the light product methanol from the top of the column while ensuring the presence of both reactants in the reaction zone to maximise the conversion to lactic acid. For inverted column, reboil ratio policy plays an important role in removing the lactic acid from the bottom of the column while ensuring the presence of both reactants in the reaction zone to maximise the conversion to lactic acid. For some cases (although limited) it is observed that for low lactic acid product purity the conventional column outperforms the inverted column while for high product purity the inverted column outperforms the conventional column in terms of batch time. © 2011 Elsevier B.V.

Elsari M.,Academy of Graduate Studies
17th International Congress on Sound and Vibration 2010, ICSV 2010 | Year: 2010

In this paper, the results of an experimental investigation into the suppression of combustion oscillations in gas-fired appliances by the use of passive resistive devices are presented. Passive resistive devices were in many cases successful in completely suppressing combustion oscillations in both the experimental combustion system and in a domestic central heating boiler. The results obtained from this investigation showed that a Cerablanket sandwiched between the burner head and the distribution plate in the case of experimental combustion system and a cylindrical Cerab-lanket sheet in the case of a domestic combustion system were effective devices for suppressing combustion oscillations, which can be applied to practical combustion systems.

Sibi G.,Academy of Graduate Studies
Research Journal of Environmental Toxicology | Year: 2015

Autotrophic cultivation of microalgae induces low biomass and lipid production and is difficult to be used in pilot scale production. Heterotrophic and mixotrophic algae allows higher growth rate, which in turn can accumulate higher biomass and lipid. Enhanced biomass and lipid production is crucial to use oleaginous microalgae for industrial application of biodiesel production. A fresh water microalga was isolated from waste water treatment plant and identified as Scenedesmus obliquus. The isolate was grown under varying cultural and nutrient conditions to increase biomass and lipid production. For this purpose, CO2 (10-160 mL min-1), temperature (20-45°C), fructose, maltose, glucose, sucrose and starch (10-50 g L-1), urea, sodium nitrate, potassium nitrate, ammonium nitrate and ammonium chloride (0.2-1.0 g L-1) were used. Optimum conditions were found by calculating specific growth rate and used to determine their influence on biomass and lipid production. At 40 mL minG1 (0.51%) CO2 concentration, 18.17 g L-1 biomass and 64.2% lipid production was obtained from the isolate. Glucose at 20 g L-1 have produced 18.62 g L-1 and 62.6% whereas sodium nitrate at 0.8 g L-1 resulted in 14.64 g L-1 and 65.1% of biomass and lipid production at the end of 20 days culturing period. Temperature of 25°C was found optimum where 12.38 g L-1 and 60.9% of biomass and lipid were obtained. Based on the results, by choosing optimum cultural conditions and nutrient composition of the growth medium it is possible to increase both biomass and lipid production in microalgae. © 2015 Academic Journals Inc.

Mujtaba I.M.,University of Bradford | Edreder E.A.,Libyan Petroleum Institute | Emtir M.,Academy of Graduate Studies
Applied Energy | Year: 2012

Lactic acid is widely used as a raw material for the production of biodegradable polymers and in food, chemical and pharmaceutical industries. The global market for lactic acid is expected to reach 259 thousand metric tons by the year 2012. For batch production of lactic acid, the traditional process includes the following steps: (i) esterification of impure lactic acid with methanol in a batch reactor to obtain methyl lactate (ester), (ii) separation of the ester in a batch distillation, (iii) hydrolysis of the ester with water in a batch reactor to produce lactic acid and (iv) separation of lactic acid (in high purity) in a batch distillation. Batch reactive distillation combines the benefit of both batch reactor and batch distillation and enhances conversion and productivity (Taylor and Krishna, 2000 [1]; Mujtaba and Macchietto, 1997 [2]). Therefore, the first and the last two steps of the lactic acid production process can be combined together in batch reactive distillation (Fig. 1) processes. However, distillation (batch or continuous) is an energy intensive process and consumes large amount of thermal energy (via steam). This paper highlights how significant (over 50%) reduction in thermal energy consumption can be achieved for lactic acid production process by carefully controlling the reflux ratio but without compromising the product specification. In this paper, only the simultaneous hydrolysis of methyl lactate ester and the separation of lactic acid using batch reactive distillation is considered. © 2010 Elsevier Ltd.

Al-Sheikh Ali K.S.,Academy of Graduate Studies
WCE 2010 - World Congress on Engineering 2010 | Year: 2010

Continuation of the current research activities undertaken at the academy of graduate studies aimed to improve the rainfall rate measurements by radar, so three empirically derived Z-R relationships, for drizzle, moderate, and heavy rain are needed. For the purpose C-band weather radar of wave length(5.5 cm) was used in this research, where the radar reflectivity was calibrated with the rainfall rates measured by four weather stations located within the range of radar wave propagations. Three Z-R relations were established and the results compared with the general formula of Tripoli City for resent rain storms detected in the region. Progress has been achieved and the standard deviations for each cases was also given.

Sibi G.,Academy of Graduate Studies
Journal of Environmental Science and Technology | Year: 2015

The aim of this study was to evaluate the hydrolysates from crop residues as low cost carbon and nitrogen source for algal cultivation. The enzymatic hydrolysates of sweet sorghum (SSH) and rice straw (RSH) were used for heterotrophic cultivation of Chlorella vulgaris and Scenedesmus obliquus. Sugar concentration of 36.5 and 30.3 g LG1 were obtained in SSH and RSH, whereas, the nitrogen content was 10.6 and 19.5 mg LG1. Basal media with glucose was used as control and hydrolysates medium was used alone and in combination to determine its efficiency on microalgal biomass and lipid production. Maximum biomass was achieved in combined hydrolysates medium in C. vulgaris (4.8 g LG1) followed by S. obliquus (4.3 g LG1). Total lipid content of Chlorella was ranged from 11.26-29.36 and 15.43-27.24% in Scenedesmus. The qualitative analysis of fatty acids showed very high values of stearic acid (28.41 and 31.01%) and palmitic acid (23.54 and 26.21%) in both microalgae. This study could establish that the hydrolysates from sweet sorghum stem and rice straw can be used as growth medium for microalgal cultivation and opens new possibilities of exploiting crop residues for industrial applications. © 2015 Asian Network for Scientific Information.

Elghawi U.M.,Academy of Graduate Studies | Mayouf A.M.,Ningbo University
Fuel | Year: 2014

The analysis of carbonyl species of a gasoline fuelled Spark-Ignition and Homogeneous Charge Compression Ignition (SI/HCCI) engine operating modes was performed upstream and downstream of a three way catalyst (TWC) converter. All data were obtained during steady-state, fully warmed-up operation at different engine conditions, using a winter grade commercial gasoline containing 2% w/w ethanol (C2H5OH). Qualitative and quantitative analysis of carbonyl compounds in exhaust gases were performed using 2,4- dinitrophenylhydrazine (DNPH)-high-performance liquid chromatography (HPLC). The major carbonyl compounds detected in the collected samples were acetaldehyde, acrolein, benzaldehyde and m-tolualdehyde. Depending on the engine operation conditions, the percentage contribution of the carbonyl compounds to the total hydrocarbons emission in this study lies between 2.7% and 5.2%. Formation of low molecular weight carbonyl compounds was more prominent when the engine operated at low load HCCI mode (low combustion temperature), while aromatic aldehydes were more significant in the case of SI mode operation, in which the combustion temperature is relatively high compared to the temperature from low load HCCI mode. Even though, the catalyst reduced the hydrocarbons emission effectively, including the carbonyls, there is no significant effect on the emission of acetaldehyde and acrolein emissions. © 2013 Elsevier Ltd. All rights reserved.

Balasubramanian K.,Academy of Graduate Studies | Balasubramanian K.,Tamil University | Padma P.R.,Tamil University
International Journal of Pharma and Bio Sciences | Year: 2012

Plants play an indispensable part in the environment, especially as a medication to protect man from intrinsic and extrinsic ill effects imparted by stress agents. In tune with the search of antioxidant-rich plants, the leaves of Zea mays were analyzed for its antioxidant potential at three different stages of growth. The effect of the leaf extract on the oxidant stress induced in in vitro systems, which simulated in vivo conditions, were studied. The in vitro model used as a means to replace or minimize the use of live animals in experiments was goat liver slices. The aim of the present study was to assess the extent of oxidative stress, the activities and levels of antioxidants by the extracts of Zea mays in the presence and absence of oxidative stress. Our findings suggest that the hepatoprotection by Zea mays leaves against hydrogen peroxide induced oxidative stress could be due to its antioxidant property.

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