Passive Driver Research Articles

High-frequency shear wave MR elastography of parotid glands: custom driver design and preliminary results.

Parotid glands are one of the most common sites for salivary gland tumors. Conventional imaging techniques have limited usefulness in the quantitative assessment of the parotid glands, making it difficult to differentiate between healthy tissue and tumors, as well as between benign and malignant tumors. Magnetic resonance elastography (MRE) is a non-invasive technique that may potentially overcome these limitations. Nevertheless, due to the size of the parotid gland, increased elastographic resolution is required. This may be achieved by applying shear waves at higher frequencies. However, it also results in stronger attenuation, making the illumination of the parotid challenging. Here, we describe a novel passive driver tailored to the anatomy of the human face, which minimizes the distance shear waves need to travel from the source to the area of interest and thus decreases shear wave attenuation, making high-frequency shear wave MRE feasible.

The feasibility of MR elastography with transpelvic vibration for localization of focal prostate lesion

We aimed to evaluate the feasibility of MR elastography (MRE) using a transpelvic approach. Thirty-one patients who underwent prostate MRE and had a pathological diagnosis were included in this study. MRE was obtained using a passive driver placed at the umbilicus and iliac crests. The shear stiffness, clinical data, and conventional imaging findings of prostate cancer and benign prostatic hyperplasia (BPH) were compared. Inter-reader agreements were evaluated using the intraclass coefficient class (ICC). Prostate MRE was successfully performed for all patients (100% technical success rate). Nineteen cancer and 10 BPH lesions were visualized on MRE. The mean shear stiffness of cancer was significantly higher than that of BPH (5.99 ± 1.46 kPa vs. 4.67 ± 1.54 kPa, p = 0.045). One cancer was detected on MRE but not on conventional sequences. Six tiny cancer lesions were not visualized on MRE. The mean size of cancers that were not detected on MRE was smaller than that of cancers that were visible on MRE (0.8 ± 0.3 cm vs. 2.3 ± 1.8 cm, p = 0.001). The inter-reader agreement for interpreting MRE was excellent (ICC = 0.95). Prostate MRE with transpelvic vibration is feasible without intracavitary actuators. Transpelvic prostate MRE is reliable for detecting focal lesions, including clinically significant prostate cancer and BPH.

Individualized driver amplitude in liver MR elastography: a linear regression study.

Current liver magnetic resonance elastography (MRE) scans often require adjustments to driver amplitude to produce acceptable images. This could lead to time wastage and the potential loss of an opportunity to capture a high-quality image. To construct a linear regression model of individualized driver amplitude to improve liver MRE image quality. Data from 95 liver MRE scans of 61 participants, including abdominal missing volume ratio (AMVR), breath-holding status, the distance from the passive driver on the skin surface to the liver edge (Dd-l), body mass index (BMI), and lateral deflection of the passive driver with respect to the human sagittal plane (Angle α), were continuously collected. The Spearman correlation analysis and lasso regression were conducted to screen the independent variables. Multiple linear regression equations were developed to determine the optimal amplitude prediction model. The optimal formula for linear regression models: driver amplitude (%) = -16.80 + 78.59 × AMVR - 11.12 × breath-holding (end of expiration = 1, end of inspiration = 0) + 3.16 × Dd-l + 1.94 × BMI + 0.34 × angle α, with the model passing the F test (F = 22.455, P <0.001) and R2 value of 0.558. The individualized amplitude prediction model based on AMVR, breath-holding status, Dd-l, BMI, and angle α is a valuable tool in liver MRE examination.

Passive clamping driver circuit for suppressing positive and negative gate crosstalk in GaN HEMTs

Passive clamping driver circuit for suppressing positive and negative gate crosstalk in GaN HEMTs

P‐75: Development of Medium and Large Size Active Bistable State Dual&amp;Four Color Cholesteric LCDs †

Compared with cholesteric display technology, which is mainly a passive driver under 5inch, this paper report one 7.5inch actively driven bistable display device. We use cyan cholesteric liquid crystal reflecting 528nm light and red ink to achieve red &amp; white dual color display. In order to enrich the display information, one red (660nm) cell and one cyan (528nm) cell are fitted with pixel precision, and black ink is printed on the bottom, control the status of the two cells respectively, so as to achieve red, cyan, black, and white four color display. In addition, we optimized drive mode, and update traditional two‐stage drive to three‐stage drive, which improved the stability of the LCD FC state and the image quality of the display device, especially at high and low temperatures. In this paper, red&amp;white dual color and four color display technologies are the first in the LCD industry.

Compact MV-Insulated MHz Transformer-Coupled Gate Driver With Staged Turn-Off Scheme for Series-Connected Power Devices in DC Circuit Breaker Applications

The short-circuit protection equipment of dc circuit breaker (DCCB) is important for the dc grid. Also, the series-connected power devices are usually employed in the solid-state circuit breaker (SSCB) or hybrid circuit breaker (HCB) to meet the clamping voltage requirement. A simple passive gate driver and power supply solution is a critical component to drive the circuit breakers more cost-effective and reliable. This article proposed a novel compact MV-insulated transformer-coupled gate driver method, which combines the auxiliary power and gate signal together. The proposed high-frequency-modulated multilevel transformer voltage enables both the simultaneous and the staged turn-off schemes. Besides, the cascade high- and low-voltage transformer structures simplify the insulation design and demonstrate better scalability. The common-mode current could be suppressed as well using this structure. The design example of a compact 2-MHz high-voltage planar transformer with >13-kV partial-discharge-free insulation capability is illustrated. Finally, the simulation and experimental results are also given to demonstrate the feasibility of the proposed gate driver method.

A tailored passive driver for liver MRE in pediatric patients.

Magnetic resonance elastography (MRE) is increasingly used in the pediatric population for diagnosis and staging of liver fibrosis. However, the MR-compatible driver and sequences are usually those used for adult patients. Our feasibility study aimed to adapt the standardized adult MRE passive driver and vibrational parameters to a pediatric population. We designed an elliptic passive driver shaped on a torus equipped with an elastic membrane and adapted to children's morphologies. As a first step, eight children (aged 8-18 years) were enrolled in a prospective pilot study aiming to determine the threshold vibrational amplitude for MRE using a custom passive driver, based on phase aliasing assessment and the occurrence of signal void artifacts on magnitude MR images. In the second step, the practicality and the consistency of the custom driver were assessed in a further 11 pediatric patients (aged 7-18 years). In the third step, we compared our custom driver vs. the commercial driver on six adult volunteers, in terms of the reliable region of interest area within the acquired MRE slices, the shear wave maps' quality, and measured stiffness values obtained. Based on pediatric patient data, the threshold vibrational amplitude expressed as percentage of maximum output was found to be 0.4 and 1.1 times the body weight (kg) at 40 and 60 Hz frequencies, respectively. In comparison to the commercial passive driver, the custom driver improved threefold the contact with the body surface, also enabling a more comfortable examination as self-assessed by the volunteers. Our custom driver was more comfortable for the volunteers and was able to generate more homogenous shear waves, yielding larger usable hepatic area, and more reliable stiffness values.

Crossing the street in front of an autonomous vehicle: An investigation of eye contact between drivengers and vulnerable road users.

Communication between road users is a major key to coordinate movement and increase roadway safety. The aim of this work was to grasp how pedestrians (Experiment A), cyclists (Experiment B), and kick scooter users (Experiment C) sought to visually communicate with drivengers when they would face autonomous vehicles (AVs). In each experiment, participants (n = 462, n = 279, and n = 202, respectively) were asked to imagine themselves in described situations of encounters between a specific type of vulnerable road user (e.g., pedestrian) and a human driver in an approaching car. The human driver state and the communicative means of the approaching car through an external Human-Machine Interface (eHMI) were manipulated between the scenarios. The participants were prompted to rate from "never" to "always" (6-point Likert scale) the frequency with which they would seek eye contact with the human driver either in order to express their willingness to cross or to make their effective decision to cross. Our findings revealed that a passive human driver in an AV with no visual checking on the road triggered a decline in vulnerable road users' desire to communicate by eye contact (Experiments A-C). Moreover, the results of Experiment C demonstrated that the speed screen, the text message screen, and the vibrating mobile app eHMI signals diminished kick scooter users' desire to communicate visually with the human driver, with some age-based differences. This suggested a better comprehension of the approaching car's intentions by the kick scooter users, driven by the features of the eHMI.

19.3: Invited Paper: For ID application using no battery IoT system

19.3: <i>Invited Paper:</i> For ID application using no battery IoT system

Reducing passive driver fatigue through a suitable secondary motor task by means of an interactive seating system

ObjectiveThe primary objective of the study was to evaluate the effect of a secondary motor task induced by an interactive seating system (IASS) on passive driver fatigue in a monotonous simulated driving task. The effect was compared to that of a state-of-the-art massage seating system (MS), which may reduce monotony through additional tactile stimuli. The secondary objective was to compare the user experience of both systems. MethodThe independent variables were three conditions: one with the IASS, another with the MS, and a control without intervention. The study included seven dependent variables in total: a rating of subjective fatigue, three parameters measuring lane keeping ability, and three parameters reflecting fatigue-related eye movements. The duration of the simulator ride was 40 min in each condition. The study included thirty-five subjects. ResultsThe assessment of subjective fatigue and lane keeping showed that the use of the IASS resulted in significantly lower passive driver fatigue compared to the massage and control conditions.The alerting effects of the IASS were also reflected by an increased eyelid distance. Frequency and duration of blinks, however, showed no clear patterns of fatigue over time in any of the conditions. Thus, both parameters did not seem be suitable to capture passive driver fatigue in this study. Regarding user experience, the subjects preferred the IASS over the MS as well. ConclusionThe IASS showed a strong potential as an effective measure against passive driver fatigue within monotonous driving situations. The MS, on the other hand, induced no measurable effects.

Quality Control of Magnetic Resonance Elastography Using Percent Measurable Liver Volume Estimation.

Although studies have described factors associated with failed magnetic resonance elastography (MRE), little is known about what factors influence usable elastography data. To identify factors that have a negative impact on percent measurable liver volume (pMLV), defined as the proportion of usable liver elastography data relative to the volume of imaged liver in patients undergoing MRE. Retrospective. A total of 264 patients (n=132 males, n=132 females; mean age=57 years) with suspected or known chronic liver disease underwent MRE paired with a liver protocol MRI. MRE was performed on a single 1.5 T scanner using a two-dimensional gradient-recalled echo phase-contrast sequence with a passive acoustic driver overlying the right hemiliver. Stiffness maps (usable data at 95% confidence) and liver contours on magnitude images of the MRE acquisition were manually traced and used to assess mean stiffness and pMLV. Hepatic fat fraction and R2 * values were also calculated. The distance from the acoustic wave generator on the skin surface to the liver edge was measured. Two radiologists performed the MR analyses with 50 overlapping cases for inter-reader analysis. Linear regression was performed to identify factors significantly associated with pMLV. Intraclass correlation was performed for inter-reader reliability. pMLV was 31% ± 20% (range 0%-86%). Complete MRE failure (i.e. pMLV=0%) occurred in 10 patients (4%). Multivariate linear regression identified higher hepatic fat fraction, R2 *, BMI, and driver-to-liver surface distance; male sex; and lower mean liver stiffness was significantly independently associated with lower pMLV. Intraclass correlation for pMLV was 0.96, suggestive of excellent reliability. Higher fat fraction, R2 *, BMI, driver-to-liver surface distance, male sex, and lower mean liver stiffness were associated with lower pMLV. Optimization of image acquisition parameters and driver placement may improve MRE quality, and pMLV likely serves as a diagnostic utility quality control metric. 3 TECHNICAL EFFICACY STAGE: 2.

Development of Metal Bonding for Passive Matrix Micro-LED Display Applications

Recently, there are many breakthroughs of display in the high resolution and vivid colors for applications in virtual/augmented reality. In this study, we have successfully developed a $64 \times 32$ array inline structure of a micro-LED ( $\mu $ LED) display by metal bonding an LED array with a glass circuit for connecting a passive matrix IC driver. The dimension of each $\mu $ LED was $100\,\,\mu \text{m}\,\,\times 100\,\,\mu \text{m}$ . After bonding, the optoelectronic characteristics were measured to evaluate the best process. By the circuit fabricated on glass and by using a bonding design, we were able to increase the usage ratio of the epitaxy layer and reduce the cost of the $\mu $ LED display. Au–In metal bonding demonstrated an excellent bonding result that can withstand a shear force up to 12.58 kg after being reinforced with UV glue. The output power of the display was 61 mW under 120 mA (@1.9 V) current injection to the whole display and the wall plug efficiency is 26.75%.

A Single Passive Gate-Driver for Series-Connected Power Devices in DC Circuit Breaker Applications

This letter proposes a novel single passive gate driver solution based on passive devices to control series-connected power semiconductor devices for dc circuit breaker (DCCB) applications. The transient suppression devices (e.g., metal oxide varistors) are utilized to achieve natural voltage balancing among the series devices, while providing the discharge path of the gate capacitor of the upper devices. The proposed method is very simple, cost effective and more compact compared with conventional voltage balancing method-based DCCBs. Besides, gate voltage oscillation during the voltage recovery process is mitigated by the addition of an extra gate capacitor. Simulation and experimental results are provided to verify the effectiveness of proposed method.

Stiffness change of the supraspinatus muscle can be detected by magnetic resonance elastography

Magnetic resonance elastography (MRE) and ultrasound shear wave elastography (SWE) are imaging techniques to measure stiffness of the soft tissue using magnetic resonance imaging (MRI) and ultrasound images, respectively. The purpose of this study was to explore the feasibility of the MRE measurement to evaluate the change in supraspinatus (SSP) muscle stiffness before and after rotator cuff tear, and to compare the result with those of SWE. Six swine shoulders were used. The skin and subcutaneous fat were removed, and the stiffness value of the SSP muscle was measured by MRE and SWE. The MRE measurement was performed with 0.3 T open MRI and the vibration from a pneumatic driver system with active driver to a passive driver to create the shear wave in the tissue. The passive driver was placed on the center of the SSP muscle. The stiffness was estimated from the wave images using local frequency estimation methods. In the SWE measurement, the probe of the ultrasound was placed on the center of the SSP muscle. The shear wave propagation speed was measured at a depth of 1 cm from the surface, and the stiffness was calculated. After those measurements, the rotator cuff tendon was detached from the greater tuberosity, and MRE and SWE measurements were then performed in the same manner again. The differences in the stiffness values were compared between before and after the rotator cuff tendon tear on both the MRE and SWE measurements. The results indicated that stiffness values on MRE and SWE were 9.3 ± 1.8 and 10.0 ± 1.2 kPa respectively before the rotator cuff tear, and 7.3 ± 1.3 and 8.0 ± 0.8 kPa respectively after the tendon detachment. Stiffness values were significantly lower after the tendon detachment on both the MRE and SWE measurements (p < 0.05). Our results demonstrated that stiffness values of the SSP muscle on MRE and SWE were lower after rotator cuff detachment. From this result, MRE may be a feasible method for quantification of the change in rotator cuff muscle stiffness.

Effects of a seat-integrated mobilization system during passive driver fatigue

ObjectiveThe aim of this study is to evaluate the effectiveness of a seat-integrated mobilization system for maintaining vigilance under monotonous driving situations. MethodFor this purpose, vigilance indicators were compared intra-individually in a test condition with mobilization (seat-integrated stimulation) and a placebo condition under standardized conditions in a real driving study (N = 31). During a monotonous two-hour ride, physiological (brain activity by the EEG alpha spindle rate), performance-based (reaction times) and subjective indicators were recorded. ResultsThe necessary precondition for the paradigm of inducing fatigue through monotony was confirmed by a significant increase in the EEG alpha spindle rate and the subjective vigilance indices. The mobilization system had a significant impact on the most fatigue-sensitive parameter of the alpha spindle rate, whereas the other parameters of vigilance did not reflect a significant effect of mobilization. ConclusionThe Mobilization Seat is an effective measure to prevent drivers’ fatigue during monotonous situations.

Technical success rate of MR elastography in a population without known liver disease.

MR elastography (MRE) has a low technical failure rate in patients with chronic liver disease. The failure rate in an unscreened population is unknown. The purpose of this study was to determine the technical failure rate of MRE in patients with no known liver disease. In this prospective trial, 633 patients received 673 scans on a 1.5 T MRI using a standard gradient recalled echo MRE protocol. Four MRE images were acquired and repeated as necessary. Two investigators in consensus categorized each failure: 1. Anatomical masking failure; 2. Iron deposition; 3. No waves (connection problem); 4. Poor wave propagation; 5. Poor passive driver placement; 6. Patient breathing problems. Full exam failure was defined as no usable data in all slices. Partial failure was no usable data on at least one slice. 1.0% (7/673) were full failures and 7.0% (47/673) were partial failures per patient. Full failures: iron deposition-71.4% (5/7); no waves-28.6% (2/7). 4.0% (108/2733) slice failure rate: Anatomical masking failure-31.5% (34/108); Iron deposition-25.0% (27/108); No waves-13.0% (14/108); Poor wave propagation-7.4% (8/108); Poor passive driver placement-11.1% (12/108); Patient breathing problems-12.0% (13/108). The failure rate of 1% is lower than for a screened population. Iron overload was implicated in most full failures. This study demonstrates the high technical success rate of MRE in an unscreened population laying the foundation for MRE as a possible screening tool for the general public.

Quantitative analysis of vibration waves based on Fourier transform in magnetic resonance elastography.

We developed a novel magnetic resonance elastography (MRE) analysis method based on Fourier transform to assess the responsive characteristics for different tissue stiffness and degree of transmission of the vibration wave emanating from a passive driver during MRE. A phantom tissue study was conducted with an MRE sequence and vibration wave system using a clinical MR scanner. The phantom tissue consisted of two layers of agar: 0.75 wt% and 1.0 wt%. Phase-unwrapped images derived from acquired MRE phase images were used to generate a phase profile curve, with a line plotted for the phase-unwrapped images. Fourier transform was performed, and the peak value of the power spectrum was derived. The damping rate/ratio was calculated using the Hilbert transform of the phase profile. We found that the mean shear stiffness value of 1.0 wt% agar was higher than that of 0.75 wt% agar. The responsive frequency of the 0.75 wt% agar layer showed a wider range and the damping rate of the signal showed a higher value than the respective values of the 1.0 wt% agar layer. In conclusion, Fourier transform analysis of MRE enabled us to obtain more detailed information of the tissue characteristics and vibration-wave conditions.

Liver MR Elastography Technique and Image Interpretation: Pearls and Pitfalls.

Liver MR elastography is an imaging technique used to measure liver stiffness in the evaluation for possible fibrosis or cirrhosis. Liver stiffness measurement (LSM) is useful for predicting the stage of liver fibrosis. However, obtaining and reporting accurate and reliable LSMs with MR elastography require an understanding of the three core components of liver MR elastography: optimization of imaging technique, prompt quality control of images, and proper interpretation and reporting of elastogram findings. When performing MR elastography, six important technical parameters that should be optimized are patient fasting before the examination, proper passive driver placement, proper MR elastography section positioning over the largest area of the liver, use of MR elastography-related sequences at end expiration, choosing the best timing of the MR elastography sequence, and optimization of several essential pulse sequence parameters. As soon as the MR elastography examination is performed, the elastograms should be reviewed to ensure that they are of diagnostic quality so that corrective steps can be taken, if needed, and MR elastography can be repeated before the diagnostic portion of the examination concludes. Finally, the interpreting radiologist needs to understand and be able to perform the proper technique for LSMs, including determining which areas of the liver to include or avoid in the measurements; knowing which conditions, other than fibrosis or cirrhosis, can increase liver stiffness; and understanding how to report elastography results. This article reviews the proper technique for performing liver MR elastography and subsequent quality control assessment, as well as the principles for interpreting and reporting studies. This review may be helpful for implementing and operating a clinical liver MR elastography service.Online supplemental material is available for this article.©RSNA, 2019.

Application of digital human models in determination of the pedal force while driving

One of the most important tasks of the car manufacturer is the design of the interior space of the vehicle. Anthropometric characteristics of drivers are also important for designing cars. In this paper the determination of the pedal force has been performed. The force determination was made on digital human models for different populations, a total of 11 different populations of men and women. Analysing was done in the software package Ramsis and subjects were presented using “mannequin”. The obtained force values were different for different populations. The correlation between the anthropometric measures of the subjects and the force on the pedals was observed. By calculating Pearson R coefficient in both populations, female 5 % and male 95 %, it can be concluded that there is a good correlation between active foot pedal force and driver’s height (R2 = 0.84 and R2 = 0.72, respectively). In the case of maximum values of passive forces R coefficient in both populations also have a good correlation between passive pedal force and driver’s height (R2 = 0.89 for female 5% population and R2 = 0.69 for male 95 % population). The obtained results are important for designing the interior of the vehicle.

Feasibility of measuring spleen stiffness with MR elastography and splenic volume to predict hepatic fibrosis stage.

AimThe aim of this study was to investigate the relationship between spleen stiffness value, splenic volume and the liver fibrosis stages.Materials and methodsThis retrospective study was approved by the institutional review board of our institute. We enrolled 109 patients that had undergone abdominal MR imaging and histopathological examination. The preoperative MR imaging, MR elastography and laboratory data were reviewed. Liver stiffness and spleen stiffness were determined with MR elastography, and splenic volume was calculated. Liver fibrosis stage was determined using surgical pathology.ResultsThe correlation coefficient between the liver stiffness and the fibrosis stage was r = 0.72 and r = 0.62 when the passive driver was on right chest wall and the left chest wall, respectively. The correlation coefficient between the spleen stiffness and the fibrosis stage was r = 0.63 and r = 0.18 when the passive driver was on the left chest wall and the right chest wall, respectively. The correlation coefficient between the splenic volume and the fibrosis stage was r = 0.31. The diagnostic performance of spleen stiffness was similar to liver stiffness in prediction of advanced liver fibrosis. The combination of spleen stiffness and liver stiffness provided greater sensitivity in prediction of advanced fibrosis than spleen or liver stiffness alone, but no significant difference was found.ConclusionAccording to our study, the spleen stiffness value was useful in staging liver fibrosis. The combination of spleen stiffness and liver stiffness could provide higher diagnostic sensitivity than liver stiffness alone in prediction of advanced fibrosis.