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A simple analytical model based on equivalent layered approach is developed to evaluate the effective properties of magneto-electro-elastic (MEE) composites where fibers are active to electrical and magnetic domains. Although the fiber and matrix phases do not exhibit any magneto-electric coupling phenomena, the resulting MEE composite has an effective non-zero magneto-electric response. A parametric study is conducted to investigate the effects of variations in the characteristics behavior of the fiber phase on the overall magneto-electro-elastic behavior of multiferroic composite. Theoretical predictions show that the effective magneto-electric coupling constants are maximum when the piezoelectric and piezomagnetic fibers share equal volume fraction. The simulated results based on the proposed model is compared with the other models (Mori-Tanaka and finite element methods) from the literature for material coefficients [1]. The comparison shows that the model calculations are in reasonable agreement with other proposed models. � 2012 Elsevier B.V. All rights reserved.

An analytical method based on parallel and series model (equivalent layered approach) is developed to study the performance of 1-3-2 magneto-electro- elastic (MEE) composite where fibers are active to electrical and magnetic fields. Although the matrix is passive to electrical and magnetic fields, the mechanical strain field in the matrix (elastic phase) couples the electric field of the piezoelectric phase to the magnetic field of the piezomagnetic phase. The combination of three-phase (electro-magneto-elastic) composite has ductility and enhanced properties. A parametric study is conducted to investigate the influence of the ceramic base and the piezomagnetic fiber volume fraction on the modified 1-3 composite. Although the fiber and matrix phases do not exhibit any magneto-electric coupling phenomena, the resulting MEE composite has an effective non-zero magneto-electric response. The proposed model is capable of predicting the effective properties of the composite subjected to magneto-electro-mechanical loading conditions. Simulated results based on the proposed model is compared well with the other models (Mori-Tanaka and finite element methods) from the literature [1]. It is observed that there is a significant influence on effective properties of the composite due to ceramic base volume fraction (V2) of 1-3-2 type multiferroic composite. A simple phenomenological model is developed to predict the non-linear response of ferroelectric and magnetostrictive materials under high electro-magnetic loading conditions. � 2014 Elsevier B.V.

A simple antenna structure for a multiple-input-multiple-output (MIMO) system in a mobile terminal with spatial diversity is presented. A single antenna element consists of a combination of an electric dipole and a square magnetic slot. The studies with a single quasi-complementary antenna element show that the electric dipole and the square-shaped magnetic slot are partially compensating the effect of the electric conductor closely spaced to the electric dipole (0.0037-0.01¿). Simulations also show that by scaling antenna structure, a 0.7-2.1-GHz frequency bandwidth can be achieved. The measured -6-dB impedance bandwidth of the MIMO antenna prototype is from 2.0 to 5.6 GHz, corresponding to a 95% relative bandwidth. The measured S 21 is less than -19 dB within the -6-dB impedance bandwidth. The average measured total efficiency at the aforementioned bandwidth is -0.85 dB. The measured radiation patterns are presented at 2 and 5 GHz with a maximum total gain of 2.8 and 5.7 dBi, respectively. The measured envelope correlation of the MIMO antenna is less than 0.04 with 90% MIMO efficiency within the -6-dB impedance bandwidth. © 2002-2011 IEEE., This work was supported by the Finnish Funding Agency for Technology and Innovation, Nokia Devices Oulu, Pulse Finland, and Universitat Politecnica de Valencia under Project PAID-06-09-2868. The work of M. Sonkki was supported by the Tauno Tonning Foundation and Universitat Politecnica de Valencia.

In this paper we present laboratory experiments where we address the Ground Penetrating Radar (GPR) capability of monitoring oil displacement processes in porous media. This has significant applications in near-subsurface environments where remediation of contaminant such as oil-derived liquids is considered one of the major technical, economical and environmental challenges. Potential applications extend to oil reservoir fields, where technique capable of detecting the water advance towards production well is strongly required. An oil saturated sand box is flooded by water and the process is continuously monitored by a GPR placed at the sand surface and by impedance measurements taken along the sand box height. Strong radar reflections in conjunction with sharp impedance changes occur in the higher oil saturated sand layers. The displacement process is poorly described when the water goes through the lower oil saturated layers due to the reduced electromagnetic contrast. In addition, we present water flooding experiment when the sand initially presents residual water saturation. Overall, the GPR results give a good understanding of the flow dynamics in the sand box.

Injection of CO2 in the InSalah field has caused uplift of the surface, as observed by satellite geodetic techniques (InSAR). Around one of the wells, KB-502, the uplift shows anomalous behaviour: a two-lobe pattern develops in the direction of the preferred fracture orientation. This indicates the tensile opening of a fracture or a fracture zone. To understand the full behaviour of the reservoir response and the surface movement we have first performed geological modeling, reservoir simulation and history matching. This has yielded an acceptable description of the reservoir in terms of pressure history and CO2 breakthrough times. In the second place we have performed geomechanical modeling: we have developed an algorithm that models the surface deformation resulting from tensile fracture opening in a multi-layer subsurface. Both the reservoir model and a possible tensile opening of a fracture zone were input in a geomechanical analysis to understand the surface deformation pattern. Our algorithm successfully matched the global shape of a two-lobe pattern. However, the magnitude of the global surface uplift could not be made in line with the pressures around the injection well, and the surface depression above the assumed opening fracture was too narrow in comparison with the predicted response.

To monitor the migration of the injected CO2 in the Ketzin project (Germany) a permanently buried multi-component seismic array has been installed in August 2009. Besides passive seismic recordings, this monitoring system was used to record data for an active survey carried out in 2009, resulting in a 200 m long 2D seismic line roughly passing over the monitoring well Ktzi 202. This relatively small set-up is meant as a pre-screening study to demonstrate the added value of the buried sensors before installing a larger 3D array. A first analysis of the active seismic data shows, that the use of an array of buried receivers results in seismic data that offer a superior frequency content and less surface related coherent noise. This setup is also expected to lead to an increased repeatability. This paper describes the experimental set-up and first results of the acquired baseline data using the buried sensors.

We report on the electric field dependent carrier dynamics and optical absorption in nonpolar a-plane GaN-based quantum heterostructures grown on r-plane sapphire, which are surprisingly observed to be opposite to those polar ones of the same materials system and similar structure grown on c-plane. Confirmed by their time-resolved photoluminescence measurements and numerical analyses, we show that carrier lifetimes increase with increasing external electric field in nonpolar InGaN/GaN heterostructure epitaxy, whereas exactly the opposite occurs for the polar epitaxy. Moreover, we observe blue-shifting absorption spectra with increasing external electric field as a result of reversed quantum confined Stark effect in these polar structures, while we observe red-shifting absorption spectra with increasing external electric field because of standard quantum confined Stark effect in the nonpolar structures. We explain these opposite behaviors of external electric field dependence with the changing overlap of electron and hole wavefunctions in the context of Fermi's golden rule. (C) 2011 Optical Society of America

A history matching workflow, as typically used for updating of petrophysical reservoir model properties, is modified to include structural parameters including the top reservoir and several fault properties: position, slope, throw and transmissibility. A simple 2D synthetic oil reservoir produced by waterflooding is used to demonstrate issues related to observability and identifiability of structural uncertainties. A series of history matching experiments are performed that demonstrate the potential for estimation of uncertain structural parameter values. The experiments are performed with ensemble-based assisted history matching schemes that allow for the proper characterization of prior uncertainties, and in principle enable the updating of both model parameters and the dynamic states such as pressures and saturations. The results show that the approach works well when individual structural parameters are estimated and suggest further scope for building a fully integrated workflow that includes the improved construction of geo-models into the history matching loop. Copyright 2011, Society of Petroleum Engineers.

Geophysical monitoring of the dynamical behavior of subsurface reservoirs (oil, gas, CO2) remains an important issue in geophysical research. A new idea for reservoir monitoring based on electrical resistivity tomography was developed at TNO. The essential element of the so-called BSEMT (Borehole to Surface Electrical Monitoring Technique) technique is the use of one electrode below the reservoir. Computer simulations and measurements in a tank in the laboratory were carried out to assess the feasibility of the BSEMT concept. The outcome of these measurements is that the expected effect of changes in the reservoir can indeed be seen by BSEMT. The surprising part of it is that the effect is bigger than expected based on computer simulations. This point has to be clarified further. More research has to be done to optimize data acquisition configurations.

As a rule, the work of electric drives of transport mechanisms arises with variable load and with different control laws of torque and speed. That leads to redistribution of losses components and demands take it in attention. In the report, the character change of the general losses and their components are compared in different type of electric drives under change of the load. In connection with this, it is paid attention to features of redistribution of losses in the perspective for transport mechanisms electric drive with field regulated reluctance machine. This machine is characterized by increased reliability, high specific parameters, simplicity of a design and control, and opportunity work in aggressive conditions. The opportunity realization of control laws in the electric drive with reluctance machine (with independent excitation) the same as in the electric drive of direct current machine makes perspective comparison of losses in these electric drives. In the basis of the analysis lays observation that at the motors having close values of efficiency, the character of change losses components also is close though their absolute losses can differ considerably. This fact makes it possible to present the change in component losses at the change load in relative units. In this case, the bases values are taken equal to total losses in the electric motor in a nominal mode. At this, absolute losses can be different and highly significant inside each series of electric motors. The results of analysis are confirmed by laboratory measurements in electric machine stands. © 2011 SAE International.

Passive seismic imaging during CO2 injection in geological formations gains more and more interest as part of an integrated monitoring approach. For two EU CO2 storage project sites, RECOPOL - Enhanced Coal-Bed Methane pilot site in Kaniów (Poland) and CO2SINK- CO2 injection in a saline aquifer in Ketzin (Germany), the Netherlands Geological Survey (TNO) has designed and implemented multi-component permanent seismic monitoring systems for both passive and active seismic observations. To process these passive seismic data, TNO developed a software package based on spectral-ratio preprocessing of the data and back-projection of seismic events. The approach is data driven in order to meet the variations in data quality caused by temporal and spatial changes in environmental site conditions. In this paper we present the processing workflow and initial results from both sites.

In the history matching process reservoir parameters are estimated so they can be further used in a simulator to reproduce the past behaviour of the reservoir. During the last two decades the methodology evolved from manual methods to computer assisted procedures which can handle larger amounts of data. Now, when the computational power has increased enough, it is possible to perform more complicated computations and use more advance methods and at the same time choose more realistic simulation models. In spite of that, the field cases which are chosen to history match, even if more realistic they often are still synthetic. Therefore, the history matching procedure has been applied as a real case study based on Nome Field located near the Norwegian coastline. The preliminary results and the experience of handling realistic dataset are shared in this paper. The Ensemble Kalman Filter, which is recently a very popular method, has been chosen to match the well production rates and bottom-hole pressures to the real observations acquired in the segment of the field. Within the numerical experiment, permeability and porosity were estimated. Obtained results are a basis for continuation and the further improvement of the history matching process of the Nome Field. In addition, the issues encountered during the study are discussed i.e. the treatment of the flow conditions on the segment boundary and construction of initial ensemble. Copyright 2011, Society of Petroleum Engineers.

Passive seismic imaging during CO2 injection in geological formations gains more and more interest as part of an integrated monitoring approach. For two EU CO2 storage project sites, RECOPOL - Enhanced Coal-Bed Methane pilot site in Kaniów (Poland) and CO2SINK- CO2 injection in a saline aquifer in Ketzin (Germany), the Netherlands Geological Survey (TNO) has designed and implemented multi-component permanent seismic monitoring systems for both passive and active seismic observations. To process these passive seismic data, TNO developed a software package based on spectral-ratio preprocessing of the data and back-projection of seismic events. The approach is data driven in order to meet the variations in data quality caused by temporal and spatial changes in environmental site conditions. In this paper we present the processing workflow and initial results from both sites.

In this paper we present laboratory experiments where we address the Ground Penetrating Radar (GPR) capability of monitoring oil displacement processes in porous media. This has significant applications in near-subsurface environments where remediation of contaminant such as oil-derived liquids is considered one of the major technical, economical and environmental challenges. Potential applications extend to oil reservoir fields, where technique capable of detecting the water advance towards production well is strongly required. An oil saturated sand box is flooded by water and the process is continuously monitored by a GPR placed at the sand surface and by impedance measurements taken along the sand box height. Strong radar reflections in conjunction with sharp impedance changes occur in the higher oil saturated sand layers. The displacement process is poorly described when the water goes through the lower oil saturated layers due to the reduced electromagnetic contrast. In addition, we present water flooding experiment when the sand initially presents residual water saturation. Overall, the GPR results give a good understanding of the flow dynamics in the sand box.

Injection of CO2 in the InSalah field has caused uplift of the surface, as observed by satellite geodetic techniques (InSAR). Around one of the wells, KB-502, the uplift shows anomalous behaviour: a two-lobe pattern develops in the direction of the preferred fracture orientation. This indicates the tensile opening of a fracture or a fracture zone. To understand the full behaviour of the reservoir response and the surface movement we have first performed geological modeling, reservoir simulation and history matching. This has yielded an acceptable description of the reservoir in terms of pressure history and CO2 breakthrough times. In the second place we have performed geomechanical modeling: we have developed an algorithm that models the surface deformation resulting from tensile fracture opening in a multi-layer subsurface. Both the reservoir model and a possible tensile opening of a fracture zone were input in a geomechanical analysis to understand the surface deformation pattern. Our algorithm successfully matched the global shape of a two-lobe pattern. However, the magnitude of the global surface uplift could not be made in line with the pressures around the injection well, and the surface depression above the assumed opening fracture was too narrow in comparison with the predicted response.

To monitor the migration of the injected CO2 in the Ketzin project (Germany) a permanently buried multi-component seismic array has been installed in August 2009. Besides passive seismic recordings, this monitoring system was used to record data for an active survey carried out in 2009, resulting in a 200 m long 2D seismic line roughly passing over the monitoring well Ktzi 202. This relatively small set-up is meant as a pre-screening study to demonstrate the added value of the buried sensors before installing a larger 3D array. A first analysis of the active seismic data shows, that the use of an array of buried receivers results in seismic data that offer a superior frequency content and less surface related coherent noise. This setup is also expected to lead to an increased repeatability. This paper describes the experimental set-up and first results of the acquired baseline data using the buried sensors.

In the history matching process reservoir parameters are estimated so they can be further used in a simulator to reproduce the past behaviour of the reservoir. During the last two decades the methodology evolved from manual methods to computer assisted procedures which can handle larger amounts of data. Now, when the computational power has increased enough, it is possible to perform more complicated computations and use more advance methods and at the same time choose more realistic simulation models. In spite of that, the field cases which are chosen to history match, even if more realistic they often are still synthetic. Therefore, the history matching procedure has been applied as a real case study based on Nome Field located near the Norwegian coastline. The preliminary results and the experience of handling realistic dataset are shared in this paper. The Ensemble Kalman Filter, which is recently a very popular method, has been chosen to match the well production rates and bottom-hole pressures to the real observations acquired in the segment of the field. Within the numerical experiment, permeability and porosity were estimated. Obtained results are a basis for continuation and the further improvement of the history matching process of the Nome Field. In addition, the issues encountered during the study are discussed i.e. the treatment of the flow conditions on the segment boundary and construction of initial ensemble. Copyright 2011, Society of Petroleum Engineers.

Geophysical monitoring of the dynamical behavior of subsurface reservoirs (oil, gas, CO2) remains an important issue in geophysical research. A new idea for reservoir monitoring based on electrical resistivity tomography was developed at TNO. The essential element of the so-called BSEMT (Borehole to Surface Electrical Monitoring Technique) technique is the use of one electrode below the reservoir. Computer simulations and measurements in a tank in the laboratory were carried out to assess the feasibility of the BSEMT concept. The outcome of these measurements is that the expected effect of changes in the reservoir can indeed be seen by BSEMT. The surprising part of it is that the effect is bigger than expected based on computer simulations. This point has to be clarified further. More research has to be done to optimize data acquisition configurations.

The city of The Hague intends to use geothermal energy to heat approx. 4000 houses in a planned urban development area called The Hague South-West. This paper describes the application of advanced seismic interpretation workflows to help positioning a geothermal doublet consisting of one injector - and one producer well. An existing 3D seismic data volume was reprocessed and inverted to acoustic impedance. The main objectives of the study were to predict the thickness of the target Rijswijk and Delft sandstones and to visualize faults and fractures that might act as permeability barriers between injector and producer. The inverted acoustic impedance volume revealed several layers of low and high impedances in and around the targeted sandstones in which lateral stratigraphic variations are observed. To visualize faults and fractures the seismic data were first filtered using two dip-steered filters Next a similarity volume and a neural network generated Fault Cube were produced and highlighted major and minor fault systems at target levels. The study results were used to assist in picking the optimal locations for the doublet. The lack of impedance contrasts and available well data prevented further quantitative work like predicting thickness and porosity of the target sandstones.

The city of The Hague intends to use geothermal energy to heat approx. 4000 houses in a planned urban development area called The Hague South-West. This paper describes the application of advanced seismic interpretation workflows to help positioning a geothermal doublet consisting of one injector - and one producer well. An existing 3D seismic data volume was reprocessed and inverted to acoustic impedance. The main objectives of the study were to predict the thickness of the target Rijswijk and Delft sandstones and to visualize faults and fractures that might act as permeability barriers between injector and producer. The inverted acoustic impedance volume revealed several layers of low and high impedances in and around the targeted sandstones in which lateral stratigraphic variations are observed. To visualize faults and fractures the seismic data were first filtered using two dip-steered filters Next a similarity volume and a neural network generated Fault Cube were produced and highlighted major and minor fault systems at target levels. The study results were used to assist in picking the optimal locations for the doublet. The lack of impedance contrasts and available well data prevented further quantitative work like predicting thickness and porosity of the target sandstones.

A technique capable of capturing the dynamic of the reservoir fluids in the proximity of production wells would provide enormous benefit to the reservoir management; in fact, monitoring can be used to develop a feedback loop between measurements and control technologies to optimize the production. This paper examines the feasibility of a borehole radar tool for near-wellbore imaging. Modeling results show that the maximum imaging range depends mainly on the conductivity of the formation where the radar borehole system lies. Another constraint is given by the operating frequency of the system. Too low frequencies would compromise the electromagnetic wave propagation in favor of diffusion phenomena and too high frequencies would drastically attenuate the signal. In case of a relatively low conductive reservoir and a limited band of frequencies higher than 100 MHz we have defined the optimal imaging capacity of the radar system in the order of tens of meters. We suggest borehole radar measurements as a promising approach to monitor steam chamber growth in Steam Assisted Gravity Drainage (SAGD) processes and to prevent water encroachment in thin oil rims. The penetration capacity of a radar system fits the imaging depth necessary for these environments.

Uncertainty is an intrinsic phenomenon in control of gene regulatory networks (GRNs). The presence of uncertainty is related to impreciseness of GRN models due to: (1) Errors caused by imperfection of measurement devices and (2) Models' inability to fully capture a complex structure of the GRN. Consequently, there is a discrepancy between actual behaviour of the GRN and what is predicted by its mathematical model. This can result in false control signals, which can drive a cell to an undesirable state. To address the problem of control under uncertainties, a risk-sensitive control paradigm is proposed. Robustness is accomplished by minimisation of the mean exponential cost as opposed to, for instance, minimisation of the mean square cost by risk-neutral controllers. The authors derive an optimal risk-sensitive controller when a GRN is modelled by a context-sensitive probabilistic Boolean network (CSPBN). By using a relation between the relative entropy and free-energy, a relative stability of the cost achieved by the risk-sensitive controller is demonstrated when the distribution of the CSPBN attractors is perturbed, as opposed to the cost of the risk-neutral controller that exhibits increase. The use of the relation between the relative entropy and free-energy to analyse the influence of a particular attractor on the robustness of the controller is studied. The efficiency of the risk-sensitive controller is tested for the CSPBN obtained from the study of malignant melanoma. © The Institution of Engineering and Technology. 3 4 279 295

A technique capable of capturing the dynamic of the reservoir fluids in the proximity of production wells would provide enormous benefit to the reservoir management; in fact, monitoring can be used to develop a feedback loop between measurements and control technologies to optimize the production. This paper examines the feasibility of a borehole radar tool for near-wellbore imaging. Modeling results show that the maximum imaging range depends mainly on the conductivity of the formation where the radar borehole system lies. Another constraint is given by the operating frequency of the system. Too low frequencies would compromise the electromagnetic wave propagation in favor of diffusion phenomena and too high frequencies would drastically attenuate the signal. In case of a relatively low conductive reservoir and a limited band of frequencies higher than 100 MHz we have defined the optimal imaging capacity of the radar system in the order of tens of meters. We suggest borehole radar measurements as a promising approach to monitor steam chamber growth in Steam Assisted Gravity Drainage (SAGD) processes and to prevent water encroachment in thin oil rims. The penetration capacity of a radar system fits the imaging depth necessary for these environments.