1,720,990 research outputs found
Impact-based frequency up-conversion in an electret-based electrostatic energy harvester
No full textChallenges in electromagnetic field computation for neurostimulation:the road to patient-specific modeling
No full textSystem design of a low-power wireless link for neural recording in a visual prosthesis
No full textRestoring visual function in blind people through technology can be challenging but very beneficial in improving the quality of life. For most cases of blindness, the only option is to stimulate the visual cortex directly. Such a system requires external cameras, image processing and implanted electrodes. Powering, stimulating the brain, and recording neural activity is preferably done wirelessly to avoid infections. The wireless link for sending the neural activity (uplink) out of the brain is vital as the neural recording is for calibration and monitoring. Uplink requirements on (low-power) consumption at the implanted transmitter and a high data rate lead us to compare two promising wireless link options. A system-level analysis is carried out on the feasibility of impulse radio ultrawideband (IR-UWB) by a worst-case link budget. A low power CMOS IR-UWB transmitter consisting of an on-off keying (OOK) modulator and an impulse generator is proposed closely, fulfilling low-power and high data rate requirements
Brain blood perfusion and white matter integrity in accelerated cognitive ageing patiens with epilepsy
No full textParameter estimation for hyperthermia treatment planning using model-based observer design
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Effect of finite precision on em simulations for high-contrast biological media at low frequencies
No full text\u3cp\u3eAt low frequencies, biological media are characterized by extremely high permittivities. As a result, the most commonly used simulation methods, i.e. finite-difference time domain (FDTD), finite element method (FEM), and domain integral equations (DIE), suffer from severe limitations in accuracy. These limitations are caused by the round-off errors in finite-precision floating point operations. Finite precision causes error accumulation in FDTD due to the large number of time steps required to simulate one period and to maintain stability. In FEM, finite precision causes the numerical derivative to collapse due to the dependence on the mesh size. While the DIE is hardly influenced by the mesh size, the extreme permittivities cause a large difference in the order of magnitude of the various terms in the DIE.\u3c/p\u3
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