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The Northern Tunisia (Northern Africa) is a promising area for oil/gas exploration. The organic geochemitry analyses of more that 1000 source rock samples and 100 oil seeps and solid bitumens were performed using GC-MS, IRMS and Rock-Eval pyrolysis techniques. The oil seep samples were collected from the Northern onshore Tunisia, associated with fracture, fault and ftrata in the Mesozoic and Cenozoic reservoirs and seals. Three primary source rocks are studied corresponding to the Albian, Late-Cenomanian-Early Turonain and Ypresian, showing good to excellent oil/gas potential. Three secondary source rock levels of Barremian, Paleocene and Miocene age are also studied and were found to display localy low to fair source rock characteristics. Based on the geochemical data, the oil seeps from the Northeast and Northwest areas were sourced from the three primary source rocks. The Albian and the Late-Cenomanian-Early-Turonain source rocks are the major oil source in the areas. While in South area, the oil seeps was initially charged by the Albian source rock. The Late-Cenomanian-Early-Turonain is the second source rock sourcing several oil seeps. The Barremain source rock only partly contributed in the south area. The oil seeps were found in fractures associated to the NE-SW and NW-SE trending fractures.

The thrust belt domain of North Africa is an important hydrocarbon province in the Mediterranean Sea and northern Tunisia. In spite of the long history of exploration in northern Tunisia, little information is available on Ypresian source rock in the thrust belt area. In the presented study the generative potential, depositional environments, thermal maturity and oil seeps of the YpresianBouDabbous organic-rich facies were characterized by both Rock Eval and molecular analyses. The present study indicates that the BouDabbous Formation displays variable source rock potential within the different Tellian units (Kasseb, EdDiss, AinDraham and Adissa units). Organic matter content and petroleum potential are generally poor to fair (up to 1.95% and 6 kg of HC/t of rock respectively) and marine type II kerogen. An increasing maturity gradient from the SE (Kassseb unit) to the NW (Adissa unit) is well documented. Indeed, the BouDabbousfacies are: marginally mature in the front of the nappes (Kasseb unit), mature to late mature within Nefza-Ain Allega tectonic window and overmaturea long the Cap-Serrat-Ghardimaou Master Fault (Adissa unit). In addition, Oil/Oil and Oil/source rock correlations shows a positive genetic correlation between the oil seeps and the BouDabbous source rock.

Natural hydrocarbon seepage has helped petroleum exploration as a direct indicator of gas and/or oil subsurface accumulations. Surface macro-seeps are generally an indication of a fault in an active Petroleum Seepage System belonging to a Total Petroleum System. This paper describes a case study in which multiple analytical techniques were used to identify and characterize trace petroleum-related hydrocarbons and other volatile organic compounds in groundwater samples collected from Sousse aquifer (Central Tunisia). The analytical techniques used for analyses of water samples included gas chromatography-mass spectrometry (GCMS), capillary GC with flame-ionization detection, Compound Specific Isotope Analysis, Rock Eval Pyrolysis. The objective of the study was to confirm the presence of gasoline and other petroleum products or other volatile organic pollutants in those samples in order to assess the respective implication of each of the potentially responsible parties to the contamination of the aquifer. In addition, the degree of contamination at different depths in the aquifer was also of interest. The oil and gas seeps have been investigated using biomarker and stable carbon isotope analyses to perform oil-oil and oil-source rock correlations. The seepage gases are characterized by high CH4 content, very low δ13CCH4 values (-71,9 ‰) and high C1/C1–5 ratios (0.95–1.0), light deuterium–hydrogen isotope ratios (- 198 ‰) and light δ13CC2 and δ13CCO2 values (-23,8‰ and-23,8‰ respectively) indicating a thermogenic origin with the contribution of the biogenic gas. An organic geochemistry study was carried out on the more ten oil seep samples. This study includes light hydrocarbon and biomarkers analyses (hopanes, steranes, n-alkanes, acyclic isoprenoids, and aromatic steroids) using GC and GC-MS. The studied samples show at least two distinct families, suggesting two different types of crude oil origins: the first oil seeps appears to be highly mature, showing evidence of chemical and/or biological degradation and was derived from a clay-rich source rock deposited in suboxic conditions. It has been sourced mainly by the lower Fahdene (Albian) source rocks. The second oil seeps was derived from a carbonate-rich source rock deposited in anoxic conditions, well correlated with the Bahloul (Cenomanian-Turonian) source rock., {"references":["Link, W.K., 1952. Significance of oil and gas seeps in world oil\nexploration. American Association of Petroleum Geologists Bulletin 36,\n1505–1540.","Jones, V.T., Drozd, R.J., 1983. Predictions of oil or gas potential by\nnear-surface geochemistry. American Association of Petroleum\nGeologists Bulletin 67, 932–952.","Abrams, M.A., 2005. Significance of hydrocarbon seepage relative to\npetroleum generation and entrapment. Marine and Petroleum Geology\n22, 457–477.","Etiope, G., Feyzullayev, A., Baciu, C.L., 2009a. Terrestrial methane\nseeps and mud volcanoes:a global perspective of gas origin. Marine and\nPetroleum Geology 26, 333–344.","Sami Khomsi, MouradBédir, Mohamed Soussi, Mohamed Ghazi Ben\nJemia, Kmar Ben Ismail-Lattrache., 2006. Mise en évidence en\nsubsurface d'événements compressifs en Tunisie orientale (Sahel) :\ngénéralité de la phase atlasique en Afrique du Nord. C. R. Geoscience\n338 (2006) 41–49.","Layeb M. (1991):Etude géologique, géochimique et minéralogique\nrégionale des faciès riches en matière organique de la Formation Bahloul\nd'âge Cénomano-Turonien dans le domaine de la Tunisie Centrale.\nThèse de Doctorat de spécialité, Faculté des Sciences de Tunis, 209p.","Saidi M. and Inoubli H. (2001): Geochemistry and organic petrography\nof proven Tunisian source rocks (poster). 20th International Meeting of\nOrganic geochemistry (Nancy 2001).","Saidi M. (2003): Tunisian source Rocks and oils\nGeochemicalcharacteristics and Oil-Source rock correlation. Rapport\ninterne ETAP.","Saidi M. (1993): Etude géologique et géochimique des roches mères\nalbo-vraconiennes dans le domaine de la Tunisie Centro-Septentrionale.\nThèse de Doctorat de sépcialité, Université de Tunis II, 135p.\n[10] A. Belhaj Mohamed, M. Saidi and B. Ibrahim., 2014. Migration\nPathway Evaluation through Analysis of Hydrocarbon Seeps in the\nPelagian basin, Sahel of Tunisia. 76th EAGE Conference and Exhibition\n2014\n[11] Tissot, B.P., Welte, D.H., 1984. Petroleum Formation and Occurrence,\nsecond ed. Springer-Verlag, Berlin, 235 pp.\n[12] Schoell, M., 1980. The hydrogen and carbon isotopic composition of\nmethane from natural gases of various origins. Geochimica et\nCosmochimica Acta 44, 649–662.\n[13] Schoell, M., 1983. Genetic characterization of natural gases. American\nAssociation of Petroleum Geologists Bulletin 67, 2225–2238.\n[14] Whiticar, M.J., Faber, E., Schoell, M., 1986. Biogenic methane\nformation in marine and fresh water environments: CO2-reduction vs.\nacetate fermentation–Isotope evidence. Geochimica et Cosmochimica\nActa 50, 693–709.\n[15] Thompson, K. F. M., 1983, Classification and thermal history of\npetroleum based on light hydrocarbons: Geochimica et Cosmochimica\nActa, v. 47, p. 303–316, doi:10.1016/0016-7037(83)90143-6."]}

A biodegradation system used to treat the discharged concentrated liquid effluents from a tuna-processing unit is described. The study includes a characterisation of the industrial effluents, the design of a bioprocess treatment and the testing of its performance. The liquid effluent to be treated contained 1570 mg/l suspended matter, 1450 mg/l fats, a chemical oxygen demand (COD) of 11 100 mg/l and a biochemical oxygen demand (BOD) of 6600 mg/l. The designed system included a physical pre-treatment unit used to remove the fats and the suspended solids through a decanter, an anaerobic digester and an activated sludge aerated bio-reactor. The pre-treatment unit allowed the elimination of 40% of the suspended matter and fats expressed in terms of COD. The anaerobic system transformed 45% of the dissolved COD into methane gas with a production of about 0.25 m 3 methane per kg of degraded COD. The aerated treatment unit achieved 85% reduction of COD. An integrated system, combining the three steps, permitted the processing of 1.2 kg COD/m 3 per day and the removal of up to 95% of the COD with minimal energy consumption and minimal sludge production.

The Central and Meridional Atlas of Tunisia, contains significant accumulations of oil in early Cretaceous aged reservoirs. The active cretaceous hydrocarbon system is a product of unique paleogeographic and tectonic events that led to cretaceous deposition of organic-rich source rocks.The analysis of different sources rocks from the Central and Meridional Atlas of Tunisia indicates that the Albian Lower Fahdene Fm has a substantial oil-generation potential. The Cenomanian-Turonian Bahloul Fm exhibits fair to high organic matter content and petroleum potential and is immature to mature. The Jurassic source rock, located in the Southern part of this area, exhibits fair to good organic matter content and petroleum potential.Molecular characterization indicates that most of the produced oils appear to be sourced from a predominantly shaly marine and mature source rock deposited in suboxic to oxic environment. Oil stains located in the northern part of the area seems to be sourced by a marly or argillaceous limestone. Oil-oil correlations and molecular characteristics of selected source rock samples and maturation models suggests that oils were generated from similar source rock and/or organic facies. The Lower Fahdene Fm is the best source candidate to generate these fluid samples. The integration of benzocarbazoles as geochemical molecules tracer has permitted a relative estimation of the lateral migration distance for the different accumulations of the area.

This paper suggests a standalone Arabic Reading Machine using TTS (Text-to-speech) and OCR (Optical Character Recognition) software built in a user friendly way for Visually Impaired People. In the Arab world, the assistive reading technology for visually impaired people use either computer or mobile phone software, which both require the help of another person. The type of reading machines has already been developed for Latin languages and research about it has been very active since the mid 1950's. An important progress has been made, and many reading machines now provide smooth and reliable speech. Although, reading machines are the most visually impaired friendly reading assistive devices, since their hardware is specifically designed for visually impaired people, they are not yet commercialized for Arabic as it requires further work on the integration of two different systems, namely OCR (Optical Character Recognition) and TTS (Text-to-speech) systems. To answer this issue an Arabic standalone reading machine designed specifically for visually impaired people with convenient control is suggested. Also, the system of existing Latin reading machines is analyzed in details, along with existing OCR and TTS software.

Geochemical data indicate that the Late Silurian-Early Devonian Fegaguira Formation is the main source rock that has been charged the Ordovician and the Triassic reservoirs in the Chotts basin, South of Tunisia. Its good to excellent geochemical characteristic and its convenient maturity range allow it to be nominated as a good shale reservoir. The reservoir assessment was based essentially on geochemical and mineralogical elements including: (1) source-rock distribution, thickness, organic richness, maturity level, petroleum generation and migration; (2) organic facies distribution, quality and kerogen transformation; and (3) mineralogical assessment, clay type and quartz richness. A geochemical database consisting of 224 cuttings samples of the Fegaguira Formation was used to determine its geochemical characteristics including mineralogy. The examined shales show different thickness distribution that decreases towards the south east. They were subdivided into three distinct units according to their diagraphic responses, lithology and organic richness. The two upper units exhibit good total organic carbon averaging 5%, an original hydrogen index averaging 560 mg HC/g of TOC suggesting that the Fegaguira Formation was originally rich in type II organic matter (oil and gas prone kerogen), maturity ranges from 0.7 to 1.1 % R0, transformation ratio is about 0.78% and quartz richness up to 16%. Detailed framework studies in petroleum geochemistry, lithostratigraphy and mineralogy combined with conventional modeling were used to estimate the unconventional oil and gas resources of the Fegaguira Formation. The important organic content, the carbon transformation ratio, the gas derived both from kerogen cracking and oil-to-gas cracking, including the calculated porosity and the quartz percentage suggest that the Feguiguira Formation is a promising reservoir.

Several wells have been drilled in the south eastern side of Tunisia but only two wells are producing. However, to better understand the petroleum system mechanism of the area, a geochemical study was performed including oil-oil and oil-source rock correlation that was proved to be an essential tool for assessing oils occurrence, source rocks characteristics, their depositional environments and their distributions. The geochemical study was followed by 1D basin modeling to better understand the petroleum system functioning of the area. The geochemical survey is based on the analysis of a total of 214 cutting samples and 6 crude oil samples. In a first part, potential Silurian and Ordovician source rocks were analyzed by Rock Eval to characterize their petroleum potential. In the second part, DST oil samples are correlated to Silurian and Ordovician source rocks using biomarkers and light hydrocarbon fraction. Migration distances calculation was based on carbozoles and benzocarbozoles. Rock Eval results show that Silurian Hot shales exhibit good petroleum potential with mature type II oil prone kerogen, while Ordovician Shales show poor to fair petroleum potential and contain bad preserved type II kerogen. Geochemical correlations study proved that the Silurian Hot shales are the main source rock in the basin and excluded any contribution from the Ordovician shales. Carbozoles and benzocarbozoles concentrations in the oils of the northern part of the area suggest close proximity to the source kitchen while oils from the southern part seem to be sourced by a kitchen located in Ghadames basin. The 1D modeling indicates that oil and gas generation from the Silurian hot shales began in the Carboniferous at about 360 Ma and reaches the maximum generation phase in the Upper Jurassic at about 160 Ma. The Hercynian unconformity surface was the main drain of secondary migration in the basin.

Notification is a service which addresses devices and users with messages or applications to be executed immediately or at specific time. Notification is important for delivering emergency, warnings and other timed messages. Recently introduced mobile broadcast is an ideal candidate for notification services due to its constant availability and potential for simultaneous addressing of very large user groups. Mobile devices also have connectivity to non-broadcast networks which allows for extended notification relying on user interaction, bringing its scope to applications requiring a response mechanism, e.g. for voting. In this paper, extensions to include notification service into the data transport system called IP Datacast (IPDC) used in the DVB-H mobile television standard are presented. The notion of notification services is first overviewed and the notification service elements complementing IPDC in DVB-H are described. Next the notification protocols and message formats are defined and the default notification channels are explained. The presented notification system reflects the current standardization status within the DVB and introduces extensions and new functionalities.

In this work, we present a distortion-based erasure code for realizing unequal error protection in video delivery services. Prior to transmission, the resulting distortion caused by packet erasure is estimated for each of the video packets. This Information Is used to protect the video packets with higher distortion values strongly, whereas video packets with very low distortion values are not worth being protected. We present a local search algorithm that delivers near-optimal parity codes which minimize the expected overall distortion at the receiver. Furthermore, we suggest the deployment of our FEC erasure code at video proxies located at the edge to access networks with high packet erasure rates (e.g. mobile networks). This helps detecting and correcting packet losses efficiently, by tailoring the error protection code characteristics to the observed packet erasure rate of the receiver. Our erasure code is a parity code and relics solely on XOR-operations for encoding and decoding; hence, it shows very high efficiency compared to other more sophisticated codes. Simulation results show that our introduced erasure code outperforms the classical Reed-Solomon erasure codes in terms of perceived video quality, while running considerably faster.

In this work, we develop a framework for the estimation of distortion caused by packet loss. Video traffic carried over the Internet is often subject to congestion leading to packet loss and late arrivals. Depending on the characteristics of the transported video sequence and on the location of the lost packet data, the effects on the perceived video quality may vary considerably. We develop a practical model for the estimation of the distortion, introduced through some packet loss. We then deduce a metric for prioritizing video packets of a video flow for streaming over networks, based on the expected loss distortion in the perceived video quality. The evaluation of our model shows high accuracy in estimating video quality deterioration.

Streaming video over the best-effort Internet arises some challenging issues. The available bandwidth and packet transmission delays are often subject to severe changes. As a consequence, a significant ratio of video packets is dropped by network routers because of lack of capacity on congested links. The impacts of video packet drops on the observed quality at receiver side may vary from unnoticed to unacceptable. This is due to the different values of each video packet for the decoding process at the receiver. Classical queueing disciplines do not have the ability to distinguish between different packet values. It is often the case that a packet of higher value is dropped, in favor of a lower valued packet. The value of a packet is measured in terms of the induced distortion, when the packet is not received correctly. In this paper, we introduce an application-specific queueing system, which drops packets in a size-distortion optimized manner. Out of all packets present in the queue, the system selects the packets to be dropped, if necessary, in order to meet a queue size constraint while minimizing the overall distortion. Important improvements in video quality for the receiver, and an efficient utilization of the available bandwidth have been observed throughout different simulations.

The trend of wireless networking is growing. This is due to the success of IEEE 802.11 WLAN technology, which allows the extension of local area networks by mobile stations and establishing of ad-hoc networks. The latter does not need any pre-installed infrastructure. Nodes communicate directly or the traffic is relayed over intermediate wireless nodes. While there are only few nodes the performance of the network is acceptable, but with increasing number of nodes their performance of the network decreases. If TCP is used additional performance degradation is expected. However, TCP is necessary since most applications and application level protocols are based on it. The poor performance of TCP in wireless networks has several reasons, especially the communication medium with high bit error rates (BER) and TCP's optimization on fixed networks. In this paper, we present an analysis of TCP's performance in wireless and ad-hoc networks. We emphasize the role of MAC layer retransmissions without breaking the end-to-end semantic of TCP. For this, we introduce the dynamic short retry limit, which allows the adaptation of RT-S/CTS retransmission.

Streaming video over the best effort Internet raises some challenging issues. The available bandwidth and packet transmission delays are often subject to severe changes. As a consequence, a significant ratio of video packets is dropped by network routers because of lack of capacity on congested links. The impacts of video packet drops on the observed quality at the receiver may vary from unnoticeable to unacceptable. This is due to the different values of each video packet for the decoding process at the receiver. Classical queueing disciplines do not have the ability to distinguish between different packet values. It is not unusual that a packet of higher value is dropped in favor of lower valued packet. The value of a packet is measured in terms of the induced distortions when the packet is not received correctly. In this study, we introduce an application specific queueing system, which drops packets in a size-distortion optimized manner. Out of all packets present in the queue, the system selects the packets to be dropped in order to meet a queue size constraint while minimizing the overall distortion if necessary. Improvements in video quality for the receiver and an efficient utilization of the available bandwidth have been observed through different simulations.

We propose an approach for the deployment of video proxy caching for robust video transmission over lossy networks. Video packets are classified by the server according to their valuableness for the decoding process and the perceived video quality. This can be easily realized using a framework for objective video quality measurement along with the frame prediction type. When deployed within the network, e.g. in intermediate multicast routers or proxy caches, this technique helps achieving great quality improvements. By identifying the most important video packets and caching them for short time, retransmission request can be processed quickly, while saving precious time and bandwidth over retransmissions issued by the server. An analytical model as well as experiments have been developed and carried out to show the gain in video quality at the receiver side, that can be achieved through selective video packet caching and retransmission.