The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform

Angel V Peterchev - One of the best experts on this subject based on the ideXlab platform.

  • fast computational optimization of tms coil placement for individualized electric field targeting
    NeuroImage, 2021
    Co-Authors: Luis J Gomez, Moritz Dannhauer, Angel V Peterchev
    Abstract:

    Abstract Background During transcranial magnetic stimulation (TMS) a coil placed on the scalp is used to non-invasively modulate activity of targeted brain networks via a magnetically induced electric field (E-field). Ideally, the E-field induced during TMS is concentrated on a targeted cortical region of interest (ROI). Determination of the coil position and orientation that best achieve this objective presently requires a large computational effort. Objective To improve the accuracy of TMS we have developed a fast computational auxiliary dipole method (ADM) for determining the optimum coil position and orientation. The optimum coil placement maximizes the E-field along a predetermined direction or, alternatively, the overall E-field magnitude in the targeted ROI. Furthermore, ADM can assess E-field uncertainty resulting from precision limitations of TMS coil placement protocols. Method ADM leverages the electromagnetic reciprocity principle to compute rapidly the TMS induced E-field in the ROI by using the E-field generated by a virtual constant current Source residing in the ROI. The framework starts by solving for the conduction currents resulting from this ROI current Source. Then, it rapidly determines the average E-field induced in the ROI for each coil position by using the conduction currents and a fast-multipole method. To further speed-up the computations, the coil is approximated using auxiliary dipoles enabling it to represent all coil orientations for a given coil position with less than 600 dipoles. Results Using ADM, the E-fields generated in an MRI-derived head model when the coil is placed at 5,900 different scalp positions and 360 coil orientations per position (over 2.1 million unique configurations) can be determined in under 15 minutes on a standard laptop computer. This enables rapid extraction of the optimum coil position and orientation as well as the E-field variation resulting from coil positioning uncertainty. ADM is implemented in SimNIBS 3.2. Conclusion ADM enables the rapid determination of coil placement that maximizes E-field delivery to a specific brain target. This method can find the optimum coil placement in under 15 minutes enabling its routine use for TMS. Furthermore, it enables the fast quantification of uncertainty in the induced E-field due to limited precision of TMS coil placement protocols, enabling minimization and statistical analysis of the E-field dose variability.

  • fast computational optimization of tms coil placement for individualized electric field targeting
    bioRxiv, 2020
    Co-Authors: Luis J Gomez, Moritz Dannhauer, Angel V Peterchev
    Abstract:

    Background: During transcranial magnetic stimulation (TMS) a coil placed on the scalp is used to non-invasively modulate activity of targeted brain networks via a magnetically induced electric field (E-field). Ideally, the E-field induced during TMS is concentrated on a targeted cortical region of interest (ROI). Objective: To improve the accuracy of TMS we have developed a fast computational auxiliary dipole method (ADM) for determining the optimum coil position and orientation. The optimum coil placement maximizes the E-field along a predetermined direction or, alternatively, the overall E-field magnitude in the targeted ROI. Furthermore, ADM can assess E-field uncertainty resulting from precision limitations of TMS coil placement protocols. Method: ADM leverages the electromagnetic reciprocity principle to compute rapidly the TMS induced E-field in the ROI by using the E-field generated by a virtual constant current Source residing in the ROI. The framework starts by solving for the conduction currents resulting from this ROI current Source. Then, it rapidly determines the average E-field induced in the ROI for each coil position by using the conduction currents and a fast-multipole method. To further speed-up the computations, the coil is approximated using auxiliary dipoles enabling it to represent all coil orientations for a given coil position with less than 600 dipoles. Results: Using ADM, the E-fields generated in an MRI-derived head model when the coil is placed at 5,900 different scalp positions and 360 coil orientations per position (over 2.1 million unique configurations) can be determined in under 15 minutes on a standard laptop computer. This enables rapid extraction of the optimum coil position and orientation as well as the E-field variation resulting from coil positioning uncertainty. Conclusion: ADM enables the rapid determination of coil placement that maximizes E-field delivery to a specific brain target. This method can find the optimum coil placement in under 15 minutes enabling its routine use for TMS. Furthermore, it enables the fast quantification of uncertainty in the induced E-field due to limited precision of TMS coil placement protocols, enabling minimization and statistical analysis of the E-field dose variability.

Luis J Gomez - One of the best experts on this subject based on the ideXlab platform.

  • fast computational optimization of tms coil placement for individualized electric field targeting
    NeuroImage, 2021
    Co-Authors: Luis J Gomez, Moritz Dannhauer, Angel V Peterchev
    Abstract:

    Abstract Background During transcranial magnetic stimulation (TMS) a coil placed on the scalp is used to non-invasively modulate activity of targeted brain networks via a magnetically induced electric field (E-field). Ideally, the E-field induced during TMS is concentrated on a targeted cortical region of interest (ROI). Determination of the coil position and orientation that best achieve this objective presently requires a large computational effort. Objective To improve the accuracy of TMS we have developed a fast computational auxiliary dipole method (ADM) for determining the optimum coil position and orientation. The optimum coil placement maximizes the E-field along a predetermined direction or, alternatively, the overall E-field magnitude in the targeted ROI. Furthermore, ADM can assess E-field uncertainty resulting from precision limitations of TMS coil placement protocols. Method ADM leverages the electromagnetic reciprocity principle to compute rapidly the TMS induced E-field in the ROI by using the E-field generated by a virtual constant current Source residing in the ROI. The framework starts by solving for the conduction currents resulting from this ROI current Source. Then, it rapidly determines the average E-field induced in the ROI for each coil position by using the conduction currents and a fast-multipole method. To further speed-up the computations, the coil is approximated using auxiliary dipoles enabling it to represent all coil orientations for a given coil position with less than 600 dipoles. Results Using ADM, the E-fields generated in an MRI-derived head model when the coil is placed at 5,900 different scalp positions and 360 coil orientations per position (over 2.1 million unique configurations) can be determined in under 15 minutes on a standard laptop computer. This enables rapid extraction of the optimum coil position and orientation as well as the E-field variation resulting from coil positioning uncertainty. ADM is implemented in SimNIBS 3.2. Conclusion ADM enables the rapid determination of coil placement that maximizes E-field delivery to a specific brain target. This method can find the optimum coil placement in under 15 minutes enabling its routine use for TMS. Furthermore, it enables the fast quantification of uncertainty in the induced E-field due to limited precision of TMS coil placement protocols, enabling minimization and statistical analysis of the E-field dose variability.

  • fast computational optimization of tms coil placement for individualized electric field targeting
    bioRxiv, 2020
    Co-Authors: Luis J Gomez, Moritz Dannhauer, Angel V Peterchev
    Abstract:

    Background: During transcranial magnetic stimulation (TMS) a coil placed on the scalp is used to non-invasively modulate activity of targeted brain networks via a magnetically induced electric field (E-field). Ideally, the E-field induced during TMS is concentrated on a targeted cortical region of interest (ROI). Objective: To improve the accuracy of TMS we have developed a fast computational auxiliary dipole method (ADM) for determining the optimum coil position and orientation. The optimum coil placement maximizes the E-field along a predetermined direction or, alternatively, the overall E-field magnitude in the targeted ROI. Furthermore, ADM can assess E-field uncertainty resulting from precision limitations of TMS coil placement protocols. Method: ADM leverages the electromagnetic reciprocity principle to compute rapidly the TMS induced E-field in the ROI by using the E-field generated by a virtual constant current Source residing in the ROI. The framework starts by solving for the conduction currents resulting from this ROI current Source. Then, it rapidly determines the average E-field induced in the ROI for each coil position by using the conduction currents and a fast-multipole method. To further speed-up the computations, the coil is approximated using auxiliary dipoles enabling it to represent all coil orientations for a given coil position with less than 600 dipoles. Results: Using ADM, the E-fields generated in an MRI-derived head model when the coil is placed at 5,900 different scalp positions and 360 coil orientations per position (over 2.1 million unique configurations) can be determined in under 15 minutes on a standard laptop computer. This enables rapid extraction of the optimum coil position and orientation as well as the E-field variation resulting from coil positioning uncertainty. Conclusion: ADM enables the rapid determination of coil placement that maximizes E-field delivery to a specific brain target. This method can find the optimum coil placement in under 15 minutes enabling its routine use for TMS. Furthermore, it enables the fast quantification of uncertainty in the induced E-field due to limited precision of TMS coil placement protocols, enabling minimization and statistical analysis of the E-field dose variability.

Sbodio, Oscar Alberto - One of the best experts on this subject based on the ideXlab platform.

  • Desarrollo de un dispositivo para monitoreo en la línea del proceso de coagulación de la leche
    Gerencia de Comunicación e Imagen Institucional DNA SICC INTA, 2017
    Co-Authors: Sbodio, Oscar Alberto, Martinez, Elbio Dante Antonio, Tercero E.j., Didier, Mario Jose Julian, Revelli G.r.
    Abstract:

    Este trabajo describe el estudio de un dispositivo para monitorizar la coagulación enzimática o ácida de la leche. El instrumento está compuesto por un calefactor/sensor de platino, un sensor de temperatura por termoresistencia de platino, un electrodo de pH, una fuente de corriente continua constante, un sistema de adquisición de señales analógicas ligado a un programa de aplicación desarrollado que corre sobre un ordenador personal. El calefactor/sensor se construyó con un alambre de platino de 0,025 mm de diámetro, bobinado alrededor de una base cerámica cilíndrica y embebida en una termovaina protectora, lo cual permite monitorizar los cambios físicos de la leche. Las pruebas realizadas bajo condiciones de aire quieto y temperatura ambiente (25 °C), mostraron que el calefactor/sensor puede soportar una corriente continua de, por lo menos, 190 mA. Ensayos a diferentes valores de corriente continua permitieron seleccionar la corriente constante apropiada de 130 mA. Con esta corriente continua constante el experimento probó ser altamente reproducible y con una baja relación señal/ruido. El análisis de la transferencia de calor sobre la superficie de la vaina protectora del calefactor/sensor demostró que la temperatura superficial es menor a 50 °C, con lo cual no existe riesgo de desnaturalizar proteínas solubles. Los efectos de la temperatura, pH, concentración enzimática y el agregado de CaCl2 sobre las respuestas tiempo de coagulación –CT–, Tmax y firmeza “viscosidad” fueron similares a las obtenidas con otros métodos. El tamaño reducido del sensor lo hace no intrusivo, robusto, fácil de limpiar in situ o esterilizar por medio de vapor, para lo cual no necesita ser removido durante las operaciones de elaboración. Cumple con las normas sanitarias 3-A y EHEDG, lo cual permite que sea usado tanto en las líneas de producción de queso como de yogurt.In this investigation we studied a device for monitoring the enzymatic or acid coagulation of milk. The instrument consists of a platinum heater/sensor, a Platinum Resistance Temperature Detector (PRTD) temperature sensor, a pH electrode, a direct constant current Source, a digital acquisition system that, with the developed software runs on a Personal Computer. The heater/sensor was build with a 0.025 mm diameter platinum wire coiled around a ceramic structure and immersed in a small protective thermowell, allowed monitoring the physical changes of milk. Under conditions of quiet air and room temperature (25°C), tests showed that this probe was able to withstand a DC current of at least 190 mA. Different tests performed with different values of DC constant current allowed to select the appropriate current (130 mA). Using this DC constant current, this experiment proved to be highly reproducible, with low signal to noise ratio. Heat transfer analysis also showed temperatures of

  • Desarrollo de un dispositivo para monitoreo en la línea de proceso de coagulación de leche
    Instituto Nacional de Tecnología Agropecuaria, 2017
    Co-Authors: Sbodio, Oscar Alberto, Martinez, Elbio Dante Antonio, Didier, Mario Jose Julian, Tercero E. J., Revelli G. R.
    Abstract:

    Este trabajo describe el estudio de un dispositivo para monitorizar la coagulación enzimática o ácida de la leche. El instrumento está compuesto por un calefactor/sensor de platino, un sensor de temperatura por termoresistencia de platino, un electrodo de pH, una fuente de corriente continua constante, un sistema de adquisición de señales analógicas ligado a un programa de aplicación desarrollado que corre sobre un ordenador personal. El calefactor/sensor se construyó con un alambre de platino de 0,025 mm de diámetro, bobinado alrededor de una base cerámica cilíndrica y embebida en una termovaina protectora, lo cual permite monitorizar los cambios físicos de la leche. Las pruebas realizadas bajo condiciones de aire quieto y temperatura ambiente (25 °C), mostraron que el calefactor/sensor puede soportar una corriente continua de, por lo menos, 190 mA. Ensayos a diferentes valores de corriente continua permitieron seleccionar la corriente constante apropiada de 130 mA. Con esta corriente continua constante el experimento probó ser altamente reproducible y con una baja relación señal/ruido. El análisis de la transferencia de calor sobre la superficie de la vaina protectora del calefactor/sensor demostró que la temperatura superficial es menor a 50 °C, con lo cual no existe riesgo de desnaturalizar proteínas solubles. Los efectos de la temperatura, pH, concentración enzimática y el agregado de CaCl2 sobre las respuestas tiempo de coagulación –CT–, Tmax y firmeza “viscosidad” fueron similares a las obtenidas con otros métodos. El tamaño reducido del sensor lo hace no intrusivo, robusto, fácil de limpiar in situ o esterilizar por medio de vapor, para lo cual no necesita ser removido durante las operaciones de elaboración. Cumple con las normas sanitarias 3-A y EHEDG, lo cual permite que sea usado tanto en las líneas de producción de queso como de yogurt.In this investigation we studied a device for monitoring the enzymatic or acid coagulation of milk. The instrument consists of a platinum heater/sensor, a Platinum Resistance Temperature Detector (PRTD) temperature sensor, a pH electrode, a direct constant current Source, a digital acquisition system that, with the developed software runs on a Personal Computer. The heater/sensor was build with a 0.025 mm diameter platinum wire coiled around a ceramic structure and immersed in a small protective thermowell, allowed monitoring the physical changes of milk. Under conditions of quiet air and room temperature (25°C), tests showed that this probe was able to withstand a DC current of at least 190 mA. Different tests performed with different values of DC constant current allowed to select the appropriate current (130 mA). Using this DC constant current, this experiment proved to be highly reproducible, with low signal to noise ratio. Heat transfer analysis also showed temperatures of

Sheng Ye - One of the best experts on this subject based on the ideXlab platform.

  • a new dual channel resonant gate drive circuit for low gate drive loss and low switching loss
    IEEE Transactions on Power Electronics, 2008
    Co-Authors: Sheng Ye
    Abstract:

    At high-frequency applications, the gate drive loss of the power metal oxide semiconductor field-effect transistor (MOSFET) becomes quite significant. A new dual-channel low side resonant gate drive circuit is proposed in this paper. The proposed drive circuit can provide two symmetrical drive signals for driving two MOSFETs. It charges and discharges the MOSFET gate capacitor with a constant current Source. Both gate drive loss and, more importantly, switching loss can be reduced significantly. The proposed resonant gate drive circuit can be used to drive the synchronous MOSFETs in a current doubler or full-wave rectifier configuration. It can also be used to drive the primary MOSFETs in push-pull converters. Analysis, computer simulation, and experimental results show that significant power loss reduction is achieved by the proposed circuit.

Peter Schegner - One of the best experts on this subject based on the ideXlab platform.

  • the impact of supply voltage distortion on the harmonic current emission of non linear loads
    Dyna, 2015
    Co-Authors: Ana Maria Blanco, Sergey Yanchenko, Jan Meyer, Peter Schegner
    Abstract:

    Electronic devices have a non-linear characteristic and emit harmonics into the low voltage grid. Different harmonic studies analyze their impact on the grids based on different types of harmonic models. The most used model is the constant current Source. Measurements have shown that the harmonic currents emitted by electronic devices depend on the circuit topology and the existing supply voltage distortion. This paper quantifies the impact of supply voltage distortion on the harmonic current emission of individual devices and the summation of multiple devices. After a classification of the commonly used circuit topologies, a time-domain model is developed for each of them. Then the individual and combined impact of voltage harmonics on the harmonic current emission of the modeled devices is analyzed based on simulations. Finally the impact of voltage distortion on the summation of multiple devices is analyzed and the accuracy of constant current Source models is evaluated.

  • impact of supply voltage distortion on the current harmonic emission of non linear loads
    Dyna, 2015
    Co-Authors: Ana Maria Blanco, Sergey Yanchenko, Jan Meyer, Peter Schegner
    Abstract:

    Electronic devices have a non-linear characteristic and emit harmonics into the low voltage grid. Different harmonic studies analyze their impact on the grids based on different types of harmonic models. The most used model is the constant current Source. Measurements have shown that the harmonic currents emitted by electronic devices depend on the circuit topology and the existing supply voltage distortion. This paper quantifies the impact of supply voltage distortion on the harmonic current emission of individual devices and the summation of multiple devices. After a classification of the commonly used circuit topologies a time-domain model is developed for each of them. Then the individual and combined impact of voltage harmonics on the harmonic current emission of the modeled devices is analyzed based on simulations. Finally the impact of voltage distortion on the summation of multiple devices is analyzed and the accuracy of constant current Source models is evaluated.

  • impact of supply voltage distortion on the harmonic emission of electronic household equipment
    Simposio Internacional sobre la Calidad de la Energía Eléctrica - SICEL, 2013
    Co-Authors: Ana Maria Blanco Castaneda, Sergey Yanchenko, Jan Meyer, Peter Schegner
    Abstract:

    Electronic devices have a nonlinear characteristic and emit harmonics into the low voltage grid. Due to the mass-use of this equipment (consumer electronics, lamps with electronic ballast and so on) the harmonic levels in the grid are usually dominated by the emission of those devices. A lot of harmonic studies are available, which analyze their impact on the harmonic levels based on different types of harmonic models. One commonly used model is the constant current Source. Measurements have shown that the harmonic currents emitted by electronic devices significantly depend on the used circuit topology and the existing supply voltage distortion. The paper quantifies the impact of supply voltage distortion on the harmonic current emission of individual devices and the summation of multiple devices. After a classification of the commonly used circuit topologies for each of them a model is developed. Based on a comprehensive simulation framework, the individual and combined impact of the most important voltage harmonics (3 rd , 5 th , 7 th ) on the harmonic current emission of the modeled devices is analyzed by a probabilistic study. Based on the results the accuracy of constant current Source models is evaluated. Finally the impact of voltage distortion on the summation of multiple devices is analyzed and the accuracy of summation studies based on the measurements of individual equipment is assessed