bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Improved Reaction Kinetics Model Of In-Situ Combustion For Pre-Steamed Oil Sands
Authors: Yang Min , Chen Zhangxin , Harding Thomas G. 
Published: May 2016

Abstract
Steam Assisted Gravity Drainage (SAGD) is a proven commercial thermal technology for oil sands recovery, but it has some limitations including low energy efficiency during generation and transport of steam to the producing formation and high capital and operating costs making SAGD projects vulnerable to low oil prices. In-situ combustion (ISC) provides an alternative to steam injection with the advantages of lower costs and higher energy efficiency. In recent years, ISC has been evaluated as a follow-up process to SAGD with the expectation to combine the advantages of steam injection and in-situ combustion. Before the design of such a hybrid process, it is important to understand the chemical reactions between air (or oxygen) and residual oil within a SAGD chamber in the presence of water and steam in order to simulate the process with a reasonable degree of confidence.
In this study, an improved reaction kinetics model, in terms of Saturates, Aromatics, Resins, and Asphaltenes (SARA) fractions, is proposed for modelling the ISC process in pre-steamed Athabasca oil sands. From the results of a set of laboratory Ramped Temperature Oxidation (RTO) tests, including temperature profiles along a reactor and produced gas composition, the oxidation behavior at different temperatures has been carefully analyzed. Based on the analysis, a reaction kinetics model consisting of Low Temperature Oxidation (LTO), thermal cracking, and High Temperature Oxidation (HTO), has been developed. This model was then incorporated into CMG STARS to simulate RTO experiments.
From the simulation study, it was found that the coke, which is formed through cracking reactions and traditionally considered to be the main source of fuel in ISC, reacts slowly at high temperatures in the RTO tests. The other source of fuel for combustion in the RTO tests is light hydrocarbons distilled or cracked from the original bitumen. These findings have been incorporated into the proposed reaction model. The experimental results of seven RTO tests, including temperature profiles, oxygen consumption, and carbon oxides production, were successfully matched by tuning kinetic parameters.
This work greatly increases understanding of fuel sources in an ISC process. The newly improved reaction kinetics model can predict oxidation and combustion behavior of ISC for pre-steamed Athabasca oil sands under a wide range of temperatures. It also provides a solid foundation for future simulation studies and technical guidance for the design of hybrid steam-combustion processes.
Effective Thermal and Electrical Conductivity of Two-Phase Saturated Porous Media
Authors: Mohammadmoradi Peyman , Behrang Arash , Kantzas Apostolos 
Published: May 2016

Abstract
Precise pore-level knowledge of effective thermal and electrical conductivities guarantees proper thermophysical and petrophysical characterization of the multiphase saturated porous media. High resolution advancing imaging techniques and developing modeling approaches are capable of simulating pore-scale phenomena in micro- and nano-scales. In this paper, a numerical framework is presented to predict relative electrical and thermal conductivity curves of two-phase saturated pore-level structures. Displacement scenarios are first performed applying a geometrical filling process. A set of rules to construct the fluid interfaces under capillary-driven transport are implemented. Subsequently effective thermal and electrical conductivity curves, quantifying the relationship between conductivity and saturation, are determined using steady state diffusion equation. The media under consideration include three-dimensional binary images of oil/water-wet sandstone and carbonate formations and the fluid systems contain steam-oil and water-oil equilibriums. The result packages, including thermal diffusivity and conductivity, electrical conductivity, formation factor, apparent diffusion coefficient, and saturation exponent, are generated and discussed considering rock types and fluid configurations.
Nonlinear Dynamical Instability Analysis of Steam-Assisted Gravity Drainage SAGD by Using Reservoir Simulation
Authors: Zhu Da , Wang Jacky , Su Yi , Gates Ian D. 
Published: May 2016

Abstract
Numerical simulators have been extensively used in reservoir engineering for several decades. These simulators, based on energy, material, and momentum (multiphase Darcy law) balances and thermodynamic equilibrium of components between phases, solve a coupled set of nonlinear partial differential equations. We have observed multiple states for simulation of Steam-Assisted Gravity Drainage (SAGD) with multiple steam-to-oil ratios resulting at the same steam injection rate. The existence of multiple solutions and potentially limit cycle behavior and its associated bifurcation branching in the operation parameter space inspires us to consider a dynamical approach to reservoir simulation. There are four dominant states of stability: absolutely stable; neutrally stable; unstable subject to infinitesimal perturbation; and unstable subject to finite amplitude perturbation. In essence, instability is a process that releases potential energy stored in the base state to the perturbation state. In a reservoir simulation, if we impose a perturbation with a certain magnitude to a quasi-steady state, linear stability theory predicts that once the system becomes unstable, the magnitude of the perturbation grows with time infinitely. However, in reality, due to nonlinearity the system causes it to evolve to a new quasi-steady state. The questions that we are going to address in this paper are: How can we use a transient reservoir simulator to detect instability of the system that may lead to different and multiple operating states? As a case study, we will use a 2D homogeneous SAGD model. Once the model reaches a quasi-steady state, we will call it our base state. Then we impose different steam injection rate perturbations on the system and see how the system responds to these changes. Different behaviors result –for finite amplitude perturbations, the state evolves to a new state (Hopf bifurcation) (Strogatz 2014). Our goal is to use an existing commercial simulator to construct multiple operating states and describe an approach to detect them. Multiple operating states could have significant implications for process control and risk/uncertainty management of reservoir operations.
Enhanced SAGD Startup Techniques for Improved Thermal Efficiency and Conformance - A Field Test Based Investigation
Authors: Dragani J. M. , Drover K. T. 
Published: May 2016

Abstract
The SAGD process can be defined to have three sequential phases to its operating mode, namely: startup, SAGD mode and wind-down. The startup phase most commonly has the shortest operating period, yet it has significant influence on the success of the subsequent operating modes. Historically, there are two primary means to achieve startup of a SAGD well pair and are commonly referred to as circulation and bullheading. The circulation process was employed at the Grand Rapids SAGD Pilot on Well Pair 1 and Well Pair 2 in 2010 and 2012 respectively.
The circulation process is complex to optimize from a heat transfer perspective. Parameters such as well length, tubular sizing, steam injection rates, steam injection pressures, steam blanketing, and reservoir dynamics all influence the performance of the process. Transient reservoir simulation models with fully coupled well and reservoir grids are required to effectively model the process, relying on key inputs from field data to calibrate models. Typically, the objectives of circulation are to achieve a uniform heating profile along the entire length of the lateral portion of the SAGD well pair and establish fluid transmissibility between the injector and producer.
A study on startup methods was conducted with the intent of optimizing temperature conformance, thermal efficiency and circulation time. The study generated several alternative startup designs, many of which employ insulated tubing strings and varied operating conditions to optimize heat exchange and energy efficiency. A field based trial was conducted using the closed circuit startup design (Canadian patent pending) at the Grand Rapids SAGD Pilot in 2015. Results of the study and field trial suggest that the closed circuit design offers several advantages; it is a thermally efficient, able to operate at higher temperatures, can use less steam per well pair, is scalable up to 1,200 meter long laterals, and can achieve excellent thermal conformance during startup.
The findings of this field based investigation add to the knowledge base related to startup techniques and well conformance. The closed circuit technology employed at the Grand Rapids SAGD Pilot is an innovative startup design that may be used in other heavy oil and oil sands reservoirs to enhance startup and promote recovery.
A Composite Mobility Model for Ad Hoc Networks in Disaster Areas
Authors: Pomportes Stéphane , Tomasik Joanna , Vèque Véronique 
Published: May 2016

Ad hoc network is an essential means of communication in disaster scenes. Validation of new communication protocols for these networks requires exhaustive simulation runs because real life experiences can be performed exclusively during expensive civil protection exercises. The necessity of these simulations calls for realistic and reliable mobility models which take into account numerous aspects of rescue worker interventions. We propose a composite model of mobility for disaster scenarii which includes a realistic model of human displacement, team mobility, and obstacle avoidance. The comparison of its performance with those of other available models is encouraging. We believe that it can improve the veracity of rescue operation simulations.
Design, Simulation, and Performance Analysis of an INS/GPS System using Parallel Kalman Filters Structure
Authors: Duc-Tan Tran , Fortier Paul , Huynh Huu-Tue 
Published: May 2016

Thanks to the strong growth of MEMS technology, the Inertial Navigation System (INS) is widely applied to navigation and guidance of moving objects. However, there exist errors in the inertial sensor’s signals that cause unacceptable drifts. To minimize these effects on the INS system, a GPS is usually employed simultaneously with an INS in order to increase the dimension of the system; the desired parameters are estimated by Kalman filtering technique applied to the enlarged system. In this paper, we present the design, simulation and performance analysis of an INS/GPS system using two parallel Kaman filters in order to increase the accuracy of the parameter estimation process. The results show that this system could be efficiently brought to practical applications.
A Scalable Wi-Fi Based Localization Algorithm
Authors: Le Truc D. , Nguyen Nam T. 
Published: May 2016

This paper proposes an applicable and scalable approach which allows deploying the fingerprint Wi-Fi localization algorithm for different mobile devices. The original fingerprint localization algorithm performs accurately when the mobile device used in the deployment phase is the same as the mobile device used in the training phase. However, when a different mobile device is used in the deployment phase, a time-consuming re-training step (in the order of hours or days) is required to achieve the equivalent degree of accuracy. Our proposed approach replaces this re-training step by a short period of calibration (in the order of a few minutes), which can be done transparently to the user. To validate our approach, we did an analysis on collected data from a large scale experiment (14 laptops and 2 smartphones with 224-hour of collected data) and evaluated the performance on the real devices.
Improvement of Bit Rate Using M-ary Chaotic Pulse Position Modulation
Authors: Quyen Nguyen Xuan , Yem Vu Van , Hoang Thang Manh 
Published: May 2016

Recent studies have pointed out that Chaotic Pulse Position Modulation (CPPM) is a very promising method for improving privacy and security in chaos-based digital communication. Especially, CPPM provides better performance than other chaotic modulation methods in noise- and distortion-affected environments. In this paper we present our development of a robust method named M-ary CPPM which is based on the combination of the conventional CPPM and multi-symbol modulation in order to improve the transmission bit rate. The M-ary CPPM signal has a pulse train format in which each pulse is a symbol and the chaotically-varied inter-pulse time interval conveys the binary information of k bits (M = 2k). The analysis and development of modulation and demodulation schemes are presented in detail. Theoretical evaluation of Bit-Error-Rate (BER) performance in the presence of additive white Gaussian noise (AWGN) and the use of AWGN filtering is also provided. The chaotic behavior of the M-ary CPPM is investigated with the variation of modulation parameters. In order to verify the performance of the proposed schemes, numerical simulations were carried out in Simulink and comparison between simulation and theoretical results is reported.
Solving the Traveling Salesman Problem with Ant Colony Optimization: A Revisit and New Efficient Algorithms
Authors: Huan Hoang Xuan , Linh-Trung Nguyen , Dong Do Duc , Huynh Huu-Tue 
Published: May 2016

Ant colony optimization (ACO) techniques are known to be efficient for combinatorial optimization. The traveling salesman problem (TSP) is the benchmark used for testing new combinatoric optimization algorithms. This paper revisits the application of ACO techniques to the TSP and discuss some general aspects of ACO that have been previously overlooked. In fact, it is observed that the solution length does not reflect exactly the quality of a particular edge belong to the solution, but it is only used for relatively evaluating whether the edge is good or bad in the process of reinforcement learning. Based on this observation, we propose two algorithms– Smoothed Max-Min Ant System and Three-Level Ant System– which not only can be easily implemented but also provide better performance, as compared to the well-known Max-Min Ant System. The performance is evaluated by numerical simulation using benchmark datasets.
Single-machine Scheduling with Splitable Jobs and Availability Constraints
Authors: Nguyen Van Huy , Tuong Nguyen Huynh , Nguyen Hua Phung , Nguyen Thanh Hien 
Published: May 2016

This paper deals with a single machine scheduling problem with availability constraints. The jobs are splitable and lower bound on the size of each sub-job is imposed. The objective is to find a feasible schedule that minimizes the makespan. The proposed scheduling problem is proved to be NP-hard in the strong sense. Some effective heuristic algorithms are then proposed. Additionally, computational results show that the proposed heuristic performs well.
VANET Modelling and Statistical Properties of Connectivity in Urban Environment
Authors: Thuan Duong Hien , Cuu Ho Van , Do Hung Ngoc 
Published: May 2016

This paper proposes a new approach for modelling Vehicular Ad Hoc Networks (VANETs) based on stochastic geometry and point processes, where road systems are modelled as random lines process and vehicle’s locations on a road are linear Poisson point processes. We derive some functions, which show the connectivity properties of VANETs under the impact of fading and path loss, that can be used for large vehicular networks analysis.
Jamming Impact on the Performance of MIMO Space Time Block Coding Systems over Multi-path Fading Channel
Authors: Shaheen Ehab M. , Samir Mohamed 
Published: May 2016

The combined effect of broad/partial band jamming on the analysis performance of multi-input/multi-output (MIMO) space time block coding (STBC) systems over Rayleigh fading channel is often neglected in the literature. To this end, this paper investigates the impact of different kinds of jamming on the performance of MIMO STBC systems. Closed form expressions for the bit error probability (BEP) of the performance of binary phase shift keying (BPSK) STBC communication system over Rayleigh fading channel under the impact of both partial band and broad-band jamming for different number of transmitting and receiving antennas are presented. Computer simulations are provided to validate the theoretical developments. It has been found that the performance of such systems is severely deteriorated in the presence of strong jamming power (with a signal to jamming power ratio less than − 10dB) and the worst scenario occurs in the presence of broad-band jamming.
NetFPGA Based OpenFlow Switch Extension for Energy Saving in Data Centers
Authors: Vu Tran Hoang , Thanh Tran , Trong Vu Quang , Nam Pham Ngoc , Thanh Nguyen Huu 
Published: May 2016

The increasing demand for data centers in both scale and size has led to huge energy consumption. The cost and environmental impact of data centers increases due to large amounts of carbon emissions. One solution to this problem is to intelligently control the power consumption of switches used in data centers. This paper proposes an extension to OpenFlow switches to support different power saving modes. The extension includes defining new messages in the OpenFlow protocol stack and designing an OpenFlow Switch Controller (OSC) that is able to turn on/off switches and disable/enable ports. To prove the soundness of the proposed extension, the functions of an OSC has been integrated in a NetFPGA based OpenFlow switch used in the ECODANE framework. The results presented in this paper can also be used by the OpenFlow compliant switches manufacturer or by power aware research community.
On the Double Doppler Effect Generated by Scatterer Motion
Authors: Pham Viet-Ha , Taieb Mohamed Haj , Chouinard Jean-Yves , Roy Sébastien , Huynh Huu-Tue 
Published: May 2016

In a time-varying transmission channel, the received signals are subject to frequency shifts due to the Doppler effect. The Doppler frequency is dependent on the carrier frequency and channel variation rate. In a fixed wireless channel, the channel variations are caused by scatterer motion. In this paper, we investigate analytically the Doppler effects generated by scatterer motion under different scatterer velocity distributions using the ring-of-scatterers geometric model. The proposed model considers Doppler frequency components caused by scatterer mobility to both received and reflected signals at each scatterer, and therefore is called the double Doppler model. The analytical curves are compared and statistically tested with several measurement results published in the literature. At low scatterer speeds, e.g., generated by moving foliage, the exponential velocity distribution is an appropriate model to describe the time-varying nature of the fixed wireless channels. The curve fitting results also show that our analytical model better approaches the empirical curves than the single Doppler model does. However, further investigation is still needed to find a suitable scatterer velocity distribution that closely describes the double Doppler effect in fast-variation fixed wireless channels, e.g., caused by passing vehicles.
Chaotic Compressed Sensing and Its Application to Magnetic Resonance Imaging
Authors: Linh-Trung Nguyen , Minh-Chinh Truong , Tran-Duc Tan , Le Ha Vu , Do Minh Ngoc 
Published: May 2016

Fast image acquisition in magnetic resonance imaging (MRI) is important, due to the need to find ways that help relieve patient’s stress during MRI scans. Methods for fast MRI have been proposed, most notably among them are pMRI (parallel MRI), SWIFT (SWeep Imaging with Fourier Transformation), and compressed sensing (CS) based MRI. Although it promises to significantly reduce acquisition time, applying CS to MRI leads to difficulties with hardware design because of the randomness nature of the measurement matrix used by the conventional CS methods. In this paper, we propose a novel method that combines the above-mentioned three approaches for fast MRI by designing a compound measurement matrix from a series of single measurement matrices corresponding to pMRI, SWIFT, and CS. In our method, the CS measurement matrix is designed to be deterministic via chaotic systems. This chaotic compressed sensing (CCS) measurement matrix, while retaining most features of the random CS matrix, is simpler to realize in hardware. Several compound measurement matrices have been constructed and examined in this work, including CCS-MRI, CCS-pMRI, CCS-SWIFT, and CCS-pSWIFT. Simulation results showed that the proposed method allows an increase in the speed of the MRI acquisition process while not compromising the quality of the acquired MR images.
An Improved White Space Prediction Algorithm for Cognitive Radio Systems
Authors: Phong Nguyen Huu , Bao Vo Nguyen Quoc , Huynh Huu-Tue 
Published: May 2016

Cognitive radio (CR) is a promising technology to enhance the current low usage of limited frequency resources. TV white space (TVWS) - TV bands at a particular time in a particular geographic area that are not being used by licensed services - is perceived as the most suitable frequency bands for CR. This paper proposes a new prediction TVWS algorithm for CR systems based on the ITU 1546.1 and the Okumura-Hata models. The proposed algorithm is verified with the data of 22 provinces in the South of Vietnam. The numerical results confirm the advantage of the proposed algorithm as well as the possibility of TVWS CR networks.
Group Scheduling for MultiChannel in OBS Networks
Authors: Quoc Nguyen Hong , Nhat Vo Viet Minh , Son Nguyen Hoang 
Published: May 2016

Group scheduling is a scheduling operation of optical burst switching networks in which the burst header packets arriving in each timeslot will schedule their following bursts simultaneously. There have been many proposals for group scheduling (such as OBS-GS, MWIS-OS and LGS), but they consider mainly to schedule the arriving bursts which have the same wavelength on an output data channel. Another suggestion is GreedyOPT which considers the group scheduling for multichannel with the support of full wavelength converters, but it is not optimal. This article proposes another approach of group scheduling which is more optimal and has a linear complexity.
An Adaptive Bandwidth Notch Filter for GNSS Narrowband Interference Mitigation
Authors: Nguyen Tu Thi-Thanh , La The Vinh , Ta Tung Hai , Nguyen Hoang-Lan Thi , Motella Beatrice 
Published: May 2016

The low level of received signals power makes Global Navigation Satellite Systems (GNSS) receivers vulnerable to many classes of disturbing signals. Among them, narrow band interference (NBI) might cause serious receiver performance degradation. Cancellation of NBI can be implemented by using notch filters (NF), which are controlled by two parameters: the notch frequency, which specifies the band center, and the notch bandwidth, which defines the spectrum area to be removed. The literature on the topic focuses on adapting the notch frequency, without estimating the filter bandwidth. This paper proposes a method able to determine both the notch parameters, optimizing the interference suppression. The performance analysis shows a good improvement by using the adaptive bandwidth notch filter.