Sharif Digital Repository

Alkaline-Surfactant-Polymer flooding is one of the most novel chemical enhanced oil recovery methods in the petroleum industry. This method has attracted interest due to its remarkable advantages. In this work, a series of ASP floods are conducted on fractured/non-fractured carbonate rocks. The performance of the tests was investigated by various ASP floods consisting of five types of polymers, two surfactants and one common alkaline. ASP was flooded simultaneously and sequentially in four defined scenarios after water flooding. The results showed that although using hydrolysed polymers increases the recovery factor in the fractured medium, sulfonated polymers increase oil recovery even more... 

The authors simulated a reservoir by using two-layer perceptron. Indeed a model was developed to simulate the increase in oil recovery caused by bacteria injection into an oil reservoir. This model was affected by reservoir temperature and amount of water injected into the reservoir for enhancing oil recovery. Comparing experimental and simulation results and also the erratic trend of data show that the neural networks have modeled this system properly. Considering the effects of nonlinear factors and their erratic and unknown impacts on recovered oil, the perceptron neural network can develop a proper model for oil recovery factor in various conditions. The neural networks have not been... 

Although alkaline-surfactant-polymer flooding is proved to be efficient for oil recovery from heavy oil reservoirs, the displacements mechanism/efficiency of this process in fractured systems needs to more discussion, especially in five-spot patterns. In this work, several ASP flooding test were performed on fractured micromodels which were initially saturated with heavy oil at constant flow rate and different fracture geometrical characteristics conditions. The ASP solutions are constituted from 5 polymers i.e. four synthetic polymers include three hydrolyzed polyacrylamide with different molecular weight as well as a non-hydrolyzed polyacrylamide and a biopolymer, 2 surfactants i.e. a... 

Microscopic and macroscopic displacements of polymer flooding to heavy oil at various levels of salinity and connate water saturation have been investigated. Both oil-wet and water-wet conditions in fractured five-spot micromodel systems, initially saturated with the heavy crude oil are utilized. The primary contribution is to examine the role of salinity, wettability, connate water, and fracture geometry in the recovery efficiency of the system. The microscopic results revealed that the increase in the connate water saturation decreases the oil recovery, independent of the wettability conditions. Moreover, the increase in salinity of the injected fluids lowers the recovery efficiency due to... 

This paper concerns on experimental investigation of biopolymer/polymer flooding in fractured five-spot systems. In this study, a series of polymer injection processes were performed on five-spot glass type micromodels saturated with heavy crude oil. Seven fractured glass type micromodels were used to illustrate the effects of polymer type/concentration on oil recovery efficiency in presence of fractures with different geometrical properties (i.e., fractures orientation, length and number of fractures). Four synthetic polymers as well as a biopolymer at different levels of concentration were tested. Also a micromodel constituted from dead-end pores with various geometrical properties was... 

One of the most important production issues in oil fields is high water production which may lead to wells killing and reduction in an economical production period. With the increment of water production or decrease of reservoir pressure, reservoir drawdown pressure reduces which causes reduction in oil production rate. To preserve the reservoir production, we should apply one of the proposed methods; namely, increasing the reservoir pressure, preventing water source invasion or using artificial lift technique. To compensate this reduction, continuous gas injection into the wells can be used. The injected gas combines with fluid in tubing and the density of the fluid decreases, thereby... 

In this study, the authors investigate the performance of optical code-division multiple access (OCDMA) systems with belief propagation (BP)-based receivers. They propose three receivers for the optical fibre channel that provide a trade-off between detecting complexity and system performance. The first proposed receiver achieves a performance very close to the so-called known interference lower bound. The second receiver exhibits a considerably less complexity at the expense of a slight degradation in performance. They show that the third BP-based receiver, which is a simplified version of the second receiver, is surprisingly the same as the so-called multistage detector in OCDMA systems.... 

With the development of modern power systems, Smart Grid as the intelligent generation of electricity networks, has been faced with a tremendous attention. The Smart Grid systems are made up of fine-grained power grid measurements to achieve a high stability and reliability. In these networks, the data security and privacy issues for secure data sharing among the components of the system have emerged as the basic requirement. Typically, a service provider securely shares the data/commands with the smart meters under an arbitrary policy which is determined by the service providers. As the smart grid components are considered to have constrained computational resources, we cannot directly use... 

On-time delivery of network flows is crucial to ensure the quality of service of deadline-constrained applications. Today, real time applications have various uses in multimedia communications, the Internet of Things (IoT), and 5G (5th generation mobile network) technology. In Software Defined Network (SDN) architecture, the controller has a global view of the network. Hence, it is possible to enrich the features of the controller and/or forwarding devices to support real time communication. In this paper, we propose a firm real time software-defined approach (FRT-SDN) for real time communication and present a novel solution for the real time forwarding/routing of time-sensitive applications... 

This paper proposes a novel and efficient real time network architecture, named RT-TelSurg, for one of the most appealing tactile Internet applications, i.e., Telesurgery. In telesurgery, the patient's vital signs and status and the required robotic commands during the surgery should be received on time. Otherwise, the life of the patient or the safety of the operation is endangered. Hence, transmitted packets should meet their respective relative deadlines. Software-defined networking is a relatively new architecture for computer and telecommunications networks in which the network control plane is separated from the data plane. One way to achieve real time telesurgery is to employ cloud... 

Software-defined network (SDN) is an emerging network architecture in which the network control task is separated from packet forwarding. This architecture can be considered as a suitable infrastructure for fifth-generation mobile network (5G) and Internet of things due to its flexibility and dynamism. In real-time networks, time-sensitive packets that miss their deadlines are considered useless or less worthy. As with traditional networks, SDN is expected to support real-time communications and handle a variety of failures (including local controller, switch, and link failures) simultaneously. This study focuses on real-time communication of time-sensitive applications that operate on... 

In this paper, we consider a code-shifted reference (CSR) for the previously introduced internally coded time hopping UWB communication systems in order to avoid channel estimation. We evaluate the performance of our proposed scheme and compare the results with those of the uncoded coded-shifted reference (CSR) UWB system. Our numerical results show the substantial performance improvement when using the proposed scheme compared to the uncoded CSR system. ©2008 IEEE  

Background: Nutrigenomic has revolutionized our understanding of nutrition. As plants make up a noticeable part of our diet, in the present study we chose microRNAs of edible plants and investigated if they can perfectly match human genes, indicating potential regulatory functionalities. Methods: miRNAs were obtained using the PNRD database. Edible plants were separated and microRNAs in common in at least four of them entered our analysis. Using vmatchPattern, these 64 miRNAs went through four steps of refinement to improve target prediction: Alignment with the whole genome (2581 results), filtered for those in gene regions (1371 results), filtered for exon regions (66 results) and finally... 

As efficiency of PV modules decreases with temperature rise, cooling methods can increase the power output and efficiency. One of the strategies for this purpose is passive cooling by implementing fins to the backside of a module. In the present study, annual energy output of a 50 W panel is analytically calculated in two unfinned and pin-finned cases based on hourly meteorological data for Shiraz, Iran. The results show that with the installation of 2-cm, 4-cm and 6-cm aluminum pin fins with finned-to-total-backside-area ratios of 0.17, 0.27 and 0.55, the power output increases by 1.24–4.16%, compared to the unfinned case. This increase is equivalent to 1.04–3.50 kWh more electrical energy... 

Karst features have caused serious problems in many engineering projects because of their permeability and high leakage potential; a clear example is Lar Dam, 84 km northeast of Tehran in which normal water level has never been reached since the filling of its reservoir in 1980. Sometimes conventional methods of studying karst features (e.g., borings and sampling) fail to precisely reveal their underground structure and this may result in inaccurate design, extensive leakage and creation of sinkholes. In the present paper, an under-study dam site in Lajamgir, Zanjan province, northern Iran is investigated. Ground observations indicated the possibility of presence of Karst caves while borings... 

CdS nanoparticles were grown using CdSO4 and Na 2S2O3 as the precursors and thioglycerol (TG) as the capping agent. TG was shown to exhibit a catalytic role in the reaction and also acted as a capping agent. It was demonstrated that size growth is linearly related to the temperature of the reaction, i.e.the sizes can be controllably adjusted by temperature. The crystalline phase of the nanocrystals was also dependent on the temperature of growth: higher temperature favours the cubic phase. The pH also plays an important role in nanoparticle growth, as lower pH leads to a higher release rate of sulfur species. At pH as high as 10, the growth rate remains slow even at boiling temperature. This... 

Three-dimensional graphenic adsorbents have been successfully synthesized by hydrothermal reduction and applied for deep removal of dibenzothiophene (DBT) from model fuel. The nanoporous spongelike structure of the graphenic compounds was confirmed using various characterization techniques. Reduced graphene oxide (rGO), carbon black-graphene composite (CB-G), and nickel-impregnated graphene (Ni-G) showed adsorption capacities of 41.8, 46.9, and 43.3 mg of DBT g-1, respectively, and the DBT concentration in the model fuel was diminished to less than 10 ppm. Thermodynamic parameters for the adsorption process evidenced feasible and exothermic adsorption on rGO and CB-G with negative enthalpy... 

This paper studies detecting matrices in random dense and sparse Code Division Multiple Access (CDMA) systems. Detecting matrices were originally introduced in the coin weighing problem. Such matrices can be used in CDMA systems in over-loaded scheme where the number of users is greater than the number of chips. We drive some conditions in the large system limit for binary and bipolar random CDMA systems to ensure that any random matrix is a detecting matrix. Furthermore, we extend our results to sparse random ternary matrices that have been using in the sparse CDMA literature. Finally, a construction method for the sparse detecting matrices is introduced  

Ground Source Heat Pumps (GSHP), as a renewable source heating, ventilating, and air conditioning (HVAC) technology, has the highest energy efficiency among different heat pump types. One of the major drawbacks of GSHPs is the long-term ground temperature variations as a result of heat accumulation or depletion in the ground. This contribution puts forward a novel ground thermal recovery system for horizontal ground heat exchangers in a hot climate. The proposed recovery system consists of open-loop horizontal Ground-Air Heat Exchangers (GAHEs) that are buried between the horizontal Ground-Water Heat Exchangers (GWHEs). A fan supplies ambient air to the GAHE pipes when the soil around GWHE... 

In this Paper, a software-based control flow checking technique called SWTES (Software-based error detection Technique using Encoded Signatures) is presented and evaluated. This technique is processor independent and can be applied to any kind of processors and microcontrollers. To implement this technique, the program is partitioned to a set of blocks and the encoded signatures are assigned during the compile time. In the run-time, the signatures are compared with the expected ones by a monitoring routine. The proposed technique is experimentally evaluated on an ATMEL MCS51 microcontroller using Software Implemented Fault Injection (SWIFI). The results show that this technique detects about...