Sharif Digital Repository

An alternative approach to analysis, design and implementation of injection-locked quadrature oscillators is proposed in this paper. A novel technique is presented which allows the effects of the mismatches due to imbalances in the I/Q paths in transceivers (TRX) to be mitigated, and hence the orthogonality of the these vectors be maintained. This technique alleviates the effects of imbalances in a transceiver between I/Q paths, which would otherwise pose many threats to the performance of the system, namely image rejection ratio (IRR) degradation, gain reduction in mixers, desensitization of the RX, and ect. As a design example, a CMOS quadrature oscillator (QOSC) at the frequency of 3.5GHz... 

Several metals and alloys can be used to enhance the mechanical and physical properties of micro parts and components for micromechanical, micro-chemical or sensor applications. Such parts can be produced in series by the powder metallurgical process of micro metal injection moulding (μ-MIM). This paper describes a novel manufacturing route for metallic multi-material micro components, two-component micro metal injection moulding (2C-μ-MIM). Similar to "two-colour" injection moulding of plastics, the process allows the integration of multiple functions in a micro part by simultaneously injecting and joining two materials in one mould. Net-shape parts with solid material interfaces are... 

Asphaltene instability is one of the major problems in gas injection projects throughout the world. Numerous models have been developed to predict asphaltene precipitation; The scaling equation is an attractive tool because of its simplicity and not involving complex properties of asphaltene. In this work, a new scaling model is presented to account for asphaltene precipitation due to gas injection at reservoir conditions. Extensive published data from literature have been used in model preparation. To check predictive capability of the equation, miscible gas injection experiments are conducted for a southwest Iranian oil reservoir. Experimental results show that methane injection has... 

The use of water-alternating-gas injection can potentially lead to improved oil recovery from the fields; simultaneous water and gas injection is a form of water-alternating-gas injection. However, there is still an incomplete understanding of these processes and the need for comparative work is inevitable. Core flood experiments and compositional simulations of water-alternating-gas and simultaneous water and gas processes are presented. Immiscible, near miscible, and miscible modes of injection are covered. Matching process is done and optimization of design parameters (injection rate, slug size, water-alternating-gas ratio, and injection gas) is performed. Experimental data demonstrate... 

Carbon dioxide-oil relative permeability is measured under reservoir condition using core flood apparatus. Then the results are compared with Nitrogen-oil relative permeability. The results show that oil permeability is higher in Carbon dioxide injection compared to nitrogen injection. The comparison of gas permeabilities shows that at the start of injection, nitrogen and carbon dioxide relative permeability are equal, but as the gas saturation increased, Nitrogen relative permeability becomes higher. Finally, a method is proposed to calculate carbon dioxide-oil relative permeability from nitrogen-oil relative permeability. This method can be generalized to calculate relative permeability... 

Common rail diesel engines with electronic fuel injection can accurately meter the fuel injection quantity with more accurate fuel injection control capability. In this work a common rail fuel injection system of a single cylinder diesel engine has been proposed and the important parameters like injection pressure, energizing time and high pressure pipes diameter and length are designed such that to be compatible with the engine basic design in case of pressure waves and injected mass variations. A one-dimensional approach has been used to model the injector using AMESim code in which Adiabatic models have been used to model injector system. Injected mass quantity has been calculated for... 

In reservoirs that have been water flooded or gas injected, it is still a significant amount of the remaining oil. Water alternative gas injection is a tertiary oil recovery method which was used for the first time in Canada for recovering remained oil in place of reservoir. The pore-scale mechanisms of this process are not fully understood yet. Such knowledge is essential for accurate modelling of reservoir. In this study various experiments on the WAG process is carried out by means of high pressure glass type micromodel instrument. The micromodel apparatus in this experiment was capable to operate at pressures up to 3500 Psi and temperatures up to 85°C which is similar to conventional... 

The uniaxial viscosity and sintering stress of WC-10Co-0⊙ 9VC (wt-%) were obtained by a loading dilatometer as functions of fractional density (0⊙ 64< ρ< 0⊙ 93) and temperature (1084< T< 1297° C) according to a Newtonian constitutive law commonly used to simulate sintering. The viscosity is suggested to follow In η= a+ Q/RT+ bρ with the values of a= 52⊙ 3±4⊙ 5 and b= 16⊙ 8±0⊙ 2. Q reflects the temperature dependence of η and estimated to be 502±52 kJ mol-1. The sintering stress exhibited almost a constant value in the range of 0·05–0·4 MPa. It is shown that Rahaman's model best fits the experimental results. This paper describes experiments performed on nanostructured WC–Co feedstock to... 

Typical non-hydrocarbon gases, which have been utilized in miscible and immiscible processes, are carbon dioxide and nitrogen. These gases are usually injected separately and have been rarely utilized together as a tertiary recovery process. In this article, the authors have experimentally focused on sequential carbon dioxide and nitrogen gas injection as a new enhanced oil recovery method. The periodic injections of carbon dioxide and nitrogen have been repeated for six injection pore volumes. Sensitivity analysis of injection pressure, injection volume, and injection rate has also been investigated in core flood experiments. The experimental results have revealed that a sequential miscible... 

Many reservoir and production engineers face asphaltene precipitation as a major problem during miscible carbon dioxide flooding projects. Experimental studies regarding asphaltene precipitation are therefore employed to assist in selecting appropriate facilities and proper operation schemes. During this study, a series of high pressure, high temperature experiments are designed and performed to analyze asphaltene precipitation behavior of an Iranian light reservoir crude at reservoir conditions due to natural production and miscible CO2 gas injection. For both sets of experiments, two different temperature levels (including reservoir temperature) are selected to investigate the role of... 

A classical question of Yoneda asks when the tensor product of two injective modules is injective. A complete answer to this question was given by Enochs and Jenda in 1991. In this paper the analogue question for pure-injective modules is studied  

Permeability reduction in porous media as a result of frail and tenuous fine particles migration would decrease the productivity index in the subterranean reservoirs. During reservoir stimulation by injecting fluids into the reservoir, as the salinity condition of the formation brine changes, fine particles initiate the triggering process. In this study, MgO-based nanofluid as a fines fixation agent was stably prepared based on the particle size distribution and characterized through transmission electron microscopy analysis. Afterward, several core flooding tests were performed using Berea sandstone cores to study the effect of nanofluid injection on fines fixation in the water shock... 

In this article a series of experiments were performed to demonstrate the effect of carbon dioxide injection pressure on a huff and puff process. The experimental data are used in a lab-scale model simulated with a commercial simulator to investigate the effect of soaking time, injection pore volume, and rate of injection on the heavy oil recovery. The result of experiments showed that a huff and puff process under miscible pressure conditions gives the most recovery. Simulation results illustrated that there is an optimum value for soaking time, which, for soaking times less than this value, recovery increases and for values greater than optimum the recovery decreases. The simulation study... 

This paper proposes a full-featured fault injection framework to assess reliability of FPGA-based designs. The framework provides non-intrusiveness, portability, flexibility and performance in reliability evaluation of FPGA-based designs against adverse effects of SEUs. It works in a non-intrusive manner, allowing the reliability of ready-to-be-released designs to be assessed independently, without any intrusion into their place and route characteristics. We have studied implications of framework's intrusiveness into design under test by comparing proposed non-intrusive framework with previous intrusive methods; up to 5% deviation in the number of effective faults is observed in intrusive... 

CO2 injection is a potentially viable method of enhanced oil recovery for medium oil reservoirs. The authors compare the effect of gas injection strategy (simultaneous water-alternating gas [SWAG], water-alternating gas [WAG], and continuous gas injection [CGI]) on recovery in immiscible, near-miscible, and miscible modes of injection. It has been proved that CGI is not the most efficient injection scenario in oil-wet reservoirs. Miscible and near-miscible core flood tests demonstrated high oil recoveries in all injection strategies due to high capillary numbers achieved as a result of miscibility. The fluid mechanics of floods were discussed using pressure drop data, different mechanics was... 

[66Ga]gallium chitosan complex was prepared with a high radiochemical purity (> 99%) in dilute acetic acid solution. The radiochemical purity of [66Ga]gallium chitosan complex was checked by using paper chromatography technique. The prepared complex solution was injected intratumoral to fibrosarcoma-bearing mice and the leakage of radioactivity from injection site was investigated. Approximately, 85.4% of the injected dose was retained in the injection site 54 h after injection and most of the leaked radioactivity was accumulated in the blood, liver (0.5%) and lung (6.5%)  

The results of the minimum miscibility pressure (MMP) determination for miscible injection of CO2 and an associated gas of one of Iranian gas reservoirs into two different oil samples using a slim tube device are presented. For an effective determination of the MMP cell-to-cell slim tube simulation was performed for each case before performing the slim tube experiment and the results were used to determine the pressure intervals in the slim tube experiment. A comparison between the measured MMP values from the slim tube experiments and those calculated by cell-to-cell simulation revealed that the cell-to-cell simulation can be a substitute to slim tube test in cases where time is a primary... 

Production optimization is defined as the process of maximizing oil production over the long term while minimizing total production costs. The overall goal is to achieve the optimum profitability from the well or field. In this process, the reservoir system can be considered as a multiple input–output system. In this complex system injection and production wells are known as inputs and outputs. The output of the system is often affected by various parameters consisting reservoir conditions, petrophysics, and PVT data. The optimization of the injector rates and number and installation of submersible pumps are the main issues which have been studied in this paper. Determining the factor with...