Enhancement of speech intelligibility in a mobile communication device by controlling operation of a vibrator based on the background noise

An improved radiation dosimeter device in an improved radiation dosimeter system provides a DC analog output voltage that is proportional to the total ionizing dose accumulated as a function of time at the location of the dosimeter in a host spacecraft, so as to operate in a system bus voltage range common to spacecraft systems with the output being compatible with conventional spacecraft analog inputs, while the total dose is measured precisely by continually monitoring the energy deposited in a silicon test mass accumulating charge including charge contribution prior to radiation threshold detection for improved measurement of the total accumulated charge with the dosimeters being daisy-chained and distributed about the spacecraft for providing a spacecraft dose profile about the spacecraft using the improved radiation dosimeter system

Learning Doppler with deep neural networks and its application to intra-cardiac echography

\u3cp\u3eCardiac ablation therapy is an effective treatment for atrial fibrillation and ventricular tachycardia that relies on the creation of electrically isolating scars, e.g. through heat. The ability to reliably visualize and assess the formation of these lesions during the procedure would greatly enhance the therapy's success rate and safety. Tissue Doppler echography enables measurement of tissue strain, and could therefore be used to monitor and quantify the stiffening of developing lesions. In tissue Doppler, the tradeoff between spatiotemporal resolution and estimation accuracy/precision is balanced by manually tweaking the fast-and slow-time range gates, with the optimal settings varying across measurements and desired clinical objectives. Convolutional neural networks have shown remarkable performance at learning to execute a large variety of signal and image processing tasks. In this work, we show how a deep neural network can be trained to robustly fulfil Doppler imaging functionality, which we term DopplerNet.\u3c/p\u3

Frequency-tunability of a collapse-mode CMUT: from modelling to pre-clinical imaging

In intracardiac echocardiography (ICE) it might be beneficial to provide ultrasound images acquired at multiple frequencies to provide high resolution and high penetration combined in a single ICE catheter. The objective of the presented work is to investigate the feasibility of a frequency-tunable imaging with a capacitive micromachined ultrasonic transducer (CMUT) operated in a collapse mode.\u3cbr/\u3eWe have developed a semi-analytic model of collapse-mode CMUT [1]. The modelled collapse-voltage is 59 V. Simulated impulse response predicts center frequency of 12.9 MHz and 16.6 MHz at a bias voltage of 100 V and 160 V, respectively. Experimental validation with a manufactured CMUT prototype [2] shows that the dynamic response and frequency-tunability are modelled with a satisfactory accuracy as shown in Fig. 1.\u3cbr/\u3eFurther experimental studies show that the center frequency of a collapse-mode CMUT can be controlled between 8 MHz and 15 MHz, if the lower bias voltage range is extended and the driving pulse is optimized. Mechanically-scanned B-mode imaging is performed on a phantom at 8 MHz, 11 MHz, and 15 MHz as a first proof of principle of a frequency-tunable imaging with a collapse-mode CMUT [4].\u3cbr/\u3eA 2x2 mm2 32-element phased-array CMUT is integrated with front-end electronics in a rigid probe prototype and connected to Verasonics system (Kirkland, WA, USA) for 2-D real-time imaging and data acquisition [4]. CMUT imaging performance is quantified in terms of resolution and penetration depth at a range of bias voltages, driving pulse frequencies, and number of pulse cycles. Based on this characterization settings for high-penetration, generic, and high-resolution imaging modes are identified. The first 2-D imaging results are shown.\u3cbr/\u3eThe developed probe prototype is tested ex vivo in a passive heart platform [5]. Images of an aortic valve acquired in high penetration (6 MHz), generic (12 MHz), and high-resolution (18 MHz) mode combine satisfying image quality and penetration depth between 2.5 cm and 10 cm as shown in Fig. 2.\u3cbr/\u3eNext, the CMUT probe prototype is further miniaturized into a 12-Fr steerable, forward-looking ICE catheter. The ICE catheter prototype is tested in vivo using a porcine animal model [5]. Images of an aortic valve are acquired in the three imaging modes with the ICE catheter placed in an ascending aorta at multiple depths. It was found that the combination of the forward-looking design and frequency tuning capability allows visualizing intracardiac structures of various sizes at different distances relative to the catheter tip, providing both wide overviews and detailed close-ups.\u3cbr/\u3e\u3cbr/\u3eReferences\u3cbr/\u3e[1] Martin Pekař, Stephan H. M. van Nispen, Rob H. B. Fey, Sergei Shulepov, Nenad Mihajlović, Henk Nijmeijer, Sensors and Actuators A: Physical (in review).\u3cbr/\u3e[2] Dirksen, P. and Lugt, A. van der (2009), Production of Pre-Collapsed Capacitive Micro-Machined Ultrasonic Transducers and Applications Thereof, Patent WO 2009037655 (A2), March 2009.\u3cbr/\u3e[3] Martin Pekař, Wendy U. Dittmer, Nenad Mihajlović, Gijs van Soest, Nico de Jong, Frequency Tuning of Collapse-Mode Capacitive Micromachined Ultrasonic Transducer, Ultrasonics, vol. 74, p. 144-152, 2017.\u3cbr/\u3e[4] Pekař, M., Mihajlović, N., Belt, H., Kolen, A. F., Rens, J. van, Budzelaar, F., Jacobs, B., Bosch, J. G., Vos, H. J., Steen, A. F. W. van der and Rem-Bronneberg, D. (2016) ‘Frequency-Agility of Collapse-Mode 1-D CMUT Array’, in Proceedings - IEEE Ultrasonics Symposium. Tours: IEEE.\u3cbr/\u3e[5] Martin Pekař, Alexander F. Kolen, Harm Belt, Frank van Heesch, Nenad Mihajlović, Imo E. Hoefer, Tamas Szili-Török, Hendrik J. Vos, Johan G. Bosch, Gijs van Soest, Antonius F. W. van der Steen. Preclinical Testing of Frequency-Tunable Capacitive Micromachined Ultrasonic Transducer Probe Prototypes, Ultrasound in Medicine and Biology (in press).\u3cbr/\u3