Predicting continuous ground reaction forces from accelerometers during uphill and downhill running: a recurrent neural network solution

Background Ground reaction forces (GRFs) are important for understanding human movement, but their measurement is generally limited to a laboratory environment. Previous studies have used neural networks to predict GRF waveforms during running from wearable device data, but these predictions are limited to the stance phase of level-ground running. A method of predicting the normal (perpendicular to running surface) GRF waveform using wearable devices across a range of running speeds and slopes could allow researchers and clinicians to predict kinetic and kinematic variables outside the laboratory environment. Purpose We sought to develop a recurrent neural network capable of predicting continuous normal (perpendicular to surface) GRFs across a range of running speeds and slopes from accelerometer data. Methods Nineteen subjects ran on a force-measuring treadmill at five slopes (0°, ±5°, ±10°) and three speeds (2.5, 3.33, 4.17 m/s) per slope with sacral- and shoe-mounted accelerometers. We then trained a recurrent neural network to predict normal GRF waveforms frame-by-frame. The predicted versus measured GRF waveforms had an average ± SD RMSE of 0.16 ± 0.04 BW and relative RMSE of 6.4 ± 1.5% across all conditions and subjects. Results The recurrent neural network predicted continuous normal GRF waveforms across a range of running speeds and slopes with greater accuracy than neural networks implemented in previous studies. This approach may facilitate predictions of biomechanical variables outside the laboratory in near real-time and improves the accuracy of quantifying and monitoring external forces experienced by the body when running.

Research on Path Planning and Tracking Control of Automatic Parking System

In this paper, we focus on the parking path planning and path tracking control under parallel parking conditions with automatic parking system as the research object. In order to solve the problem of discontinuity of curvature in the path planning of traditional arc-straight combined curve, a quintic polynomial is used to smooth the path. we design a path tracking controller based on the incremental model predictive control (MPC). The preview control based on pure tracking algorithm is used as the comparison algorithm for path tracking. The feasibility of the controller is verified by building a Simulink/CarSim co-simulation platform. In addition, the practicality of the parking controller is further verified by using the ROS intelligent car in the laboratory environment.

Development of a Personal Ultrasound Exposimeter for Occupational Health Monitoring

Prolonged exposure to airborne ultrasound in a workplace can have a detrimental influence on a worker’s well-being. Given the ever-increasing use of ultrasonic industrial equipment, it is of vital importance—and may also be regulated by law—to monitor ultrasound exposure during a normal workday as part of workplace risk assessment. However, the devices currently utilized exhibit limitations with regard to both their operational frequency and their portability (wearability). In this paper, the first prototype of a high-frequency and ultrasound personal exposimeter is presented in the light of the latest national and international standards governing high-frequency and ultrasonic noise measurement in the field of occupational health monitoring. The prototype was tested in the laboratory environment in order to assess its sound level detection capabilities in both the audible and ultrasonic frequency ranges. Several common industrial scenarios—including an ultrasonic welding machine, an ultrasonic cleaning bath, and a compressed air gun—were simulated in a laboratory environment. For each simulated set-up, a corresponding high-frequency or ultrasonic signal was fed through a specially prepared generation chain. Each experimental scenario was initially surveyed with an ultrasound level meter previously tested up to 100 kHz. This was followed by a measurement with the prototype. For this study, the simulated sound signals varied between 10 kHz and 40 kHz on the frequency scale and between 60 dB and 90 dB in amplitude. The portability of the prototype, which may be required to be worn throughout an entire workday (e.g., 8 h), was also considered. All the experiments were performed on a customized ultrasound measurement set-up within a free-field environment located at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. Results obtained suggest a good agreement between the measurements performed with both devices in the louder areas of the sound fields produced. Because the overall measurement uncertainty is highly dependent on the specificity of the individual measurement set-up and measurement procedure, an uncertainty budget estimated for the prototype considers electro-acoustical contributions only.

Quantification of the Absorption and Scattering Effects of Diffusers in a Room with Absorbent Ceiling

In ordinary public rooms, such as classrooms and offices, an absorbent ceiling is the typical first acoustic action. This treatment provides a good acoustic baseline. However, an improvement of specific room acoustic parameters, operating for specific frequencies, can be needed. It has been seen that diffusing elements can be effective additional treatment. In order to choose the right design, placement, and quantity of diffusers, a model to estimate the effect on the acoustics is necessary. This study evaluated whether an SEA model could be used for that purpose, particularly for the cases where diffusers are used in combination with an absorbent ceiling. It was investigated whether the model could handle different quantities of diffusing elements, varied diffusion characteristics, and varied installation patterns. It was found that the model was sensitive to these changes, given that the output from the model in terms of acoustic properties will be reflected by the change of diffuser configuration design. It was also seen that the absorption and scattering of the diffusers could be quantified in a laboratory environment: a reverberation chamber. Through the SEA model, these quantities could be transformed to a full-scale room for estimation of the room acoustic parameters.

Fried’s coherence length measurement of dynamic Kolmogorov type turbulence using autocorrelation function

A new method to find Fried’s coherence length of a dynamic Kolmogorov type turbulence in laboratory environment is reported in this paper. This method utilises autocorrelation function obtained from the quantitative characteristics of a rotating pseudo random phase plate in one of the arms of Mach-Zehnder interferometer. Theoretical formalism and experimental verification are presented.

Students’ Perception towards the Usefulness and Satisfaction of Practical Biochemistry Skills in a Public University versus Private University in Khartoum, Sudan (2019)

Practical biochemistry skills (PBS) teaching sessions employ experiential learning techniques to promote medical students’ understanding and recall of essential concepts and basic clinical tests. Biochemistry Practical skill sessions constitute about 45% of the contact teaching hours and between 10% - 20% of the final assessment grades, in addition the students are unacquainted about the method of assessment used. This cross sectional institutional based study aimed to assess medical students’ perception towards the practical biochemistry skills (PBS). Medical students in one public (Al-Neelain) and one private (Al-Moughtarbeen) universities, in Khartoum State were involved. After ethical approval, the questionnaire was approved after using it in a pilot study. Data collected by a questionnaire were analyzed using (SPSS version 22).Private university students have more satisfaction (58% versus 18%, p<0.001), more positive perception with PBS (49.5% versus 15.1%, p<0.001) and are more convinced that it helps to retain knowledge (68.3% versus 12.9%, p<0.001). They are more satisfied with laboratory environment (p<0.001), PBS relation to theory (p<0.001) and more aware of PBS assessment and scores allocation (p≤0.002).Medical student satisfaction and engagement with Practical biochemistry skills is likely to be driven by the students’ awareness of the relevance of these sessions to other aspects of the curriculum, to their end-of-year assessment, and to their future clinical practice rather than the laboratory environment. In conclusion, we recommend updating Practical biochemistry skills contents and assessment methods and raising students’ awareness of its importance.

Research on a Microexpression Recognition Technology Based on Multimodal Fusion

Microexpressions have extremely high due value in national security, public safety, medical, and other fields. However, microexpressions have characteristics that are obviously different from macroexpressions, such as short duration and weak changes, which greatly increase the difficulty of microexpression recognition work. In this paper, we propose a microexpression recognition method based on multimodal fusion through a comparative study of traditional microexpression recognition algorithms such as LBP algorithm and CNN and LSTM deep learning algorithms. The method couples the separate microexpression image information with the corresponding body temperature information to establish a multimodal fusion microexpression database. This paper firstly introduces how to build a multimodal fusion microexpression database in a laboratory environment, secondly compares the recognition accuracy of LBP, LSTM, and CNN + LSTM networks for microexpressions, and finally selects the superior CNN + LSTM network in the comparison results for model training and testing on the test set under separate microexpression database and multimodal fusion database. The experimental results show that a microexpression recognition method based on multimodal fusion designed in this paper is more accurate than unimodal recognition in multimodal recognition after feature fusion, and its recognition rate reaches 75.1%, which proves that the method is feasible and effective in improving microexpression recognition rate and has good practical value.

Deep-Ultraviolet (DUV)-Induced Doping in Single Channel Graphene for Pn-Junction

The electronic properties of single-layer, CVD-grown graphene were modulated by deep ultraviolet (DUV) light irradiation in different radiation environments. The graphene field-effect transistors (GFETs), exposed to DUV in air and pure O2, exhibited p-type doping behavior, whereas those exposed in vacuum and pure N2 gas showed n-type doping. The degree of doping increased with DUV exposure time. However, n-type doping by DUV in vacuum reached saturation after 60 min of DUV irradiation. The p-type doping by DUV in air was observed to be quite stable over a long period in a laboratory environment and at higher temperatures, with little change in charge carrier mobility. The p-doping in pure O2 showed ~15% de-doping over 4 months. The n-type doping in pure N2 exhibited a high doping effect but was highly unstable over time in a laboratory environment, with very marked de-doping towards a pristine condition. A lateral pn-junction of graphene was successfully implemented by controlling the radiation environment of the DUV. First, graphene was doped to n-type by DUV in vacuum. Then the n-type graphene was converted to p-type by exposure again to DUV in air. The n-type region of the pn-junction was protected from DUV by a thick double-coated PMMA layer. The photocurrent response as a function of Vg was investigated to study possible applications in optoelectronics.

CarLink: A Real-Time V2X Validation Platform for a Safe and Sustainable Mobility

<div>In this article, we present CarLink, a new simulation platform with hardware-in-the-loop (HiL), designed and implemented to reduce the time spent on field tests through the emulation of a complex vehicular scenario in a controlled laboratory environment. Specifically, CarLink can simulate a generic traffic scenario and let each vehicle in it communicate with a vehicle under test (VUT), which is actually physically available HiL and equipped with long- and short-range wireless communication capabilities. Communication between simulated vehicles and the VUT is provided by an external management unit (EMU) that integrates the virtual word with the physical one. The architecture is also designed to allow the integration of advanced driver assistance systems (ADAS) testing for the validation of future connected and automated vehicles.</div>