Investigation of a Real-Time Pressure Based Valve Timing Correction Algorithm

2017 ◽  
Author(s):  
Farid Breidi ◽  
Jordan Garrity ◽  
John Lumkes
Keyword(s):  
Real Time ◽  
High Speed ◽  
Small Error ◽  
Hydraulic Systems ◽  
Correction Algorithm ◽  
Valve Timing ◽  
Pump System ◽  
Wide Range ◽  
Delay Times ◽  
The Impact

Digital hydraulics is an emerging field in fluid power, complementing conventional hydraulic and potentially improving efficiency and dynamic performance. High speed electrically controlled on/off valves are key enablers for many digital hydraulic systems, and specifically for digital pump/motors. This work investigates a 4-quadrant 3-piston digital pump/motor utilizing two electrically controlled high speed on/off valves per displacement chamber. The test unit was simulated, built, and experimentally tested. Simulation and experimental results showed the importance of valve response times on the overall performance and efficiency of the digital pump/motor, where a small error in the delay in the valve opening or closing could lead to significant energy losses. To minimize the impact of valve variability, a real-time valve correction algorithm was developed to account for the error in valve timing. The algorithm uses the pressure readings at the low and high pressure ports to detect the time at which the pressure ripple occurred and then obtain the delay in the valve timing. It calculates the turn-on and turn-off valve delay times in all displacement chambers in a three-piston pump with two valves per chamber, detecting a total of 12 valve delay times. The code was tested for sequential flow diverting and sequential flow limiting operating modes at a wide range of displacement (25% to 100%) with pressures ranging from 25 bar to 105 bar and shaft speeds up to 700 rpm (limited by the valves speed). It was also tested for flow diverting mode and gave good results for displacements between 70% and 100%. The error in the calculated delay times was below 5% in all of the tested conditions, providing major improvements to the digital pump system, and to digital hydraulics in general.

scholarly journals An Adaptive Bitrate Switching Algorithm for Speech Applications in Context of WebRTC

2021 ◽  
Vol 17 (4) ◽  
pp. 1-21
Author(s):  
Mohannad Alahmadi ◽  
Peter Pocta ◽  
Hugh Melvin
Keyword(s):  
Real Time ◽  
Data Exchange ◽  
Quality Of Experience ◽  
End User ◽  
High Quality ◽  
Content Type ◽  
Switching Algorithm ◽  
Wide Range ◽  
The Impact

Web Real-Time Communication (WebRTC) combines a set of standards and technologies to enable high-quality audio, video, and auxiliary data exchange in web browsers and mobile applications. It enables peer-to-peer multimedia sessions over IP networks without the need for additional plugins. The Opus codec, which is deployed as the default audio codec for speech and music streaming in WebRTC, supports a wide range of bitrates. This range of bitrates covers narrowband, wideband, and super-wideband up to fullband bandwidths. Users of IP-based telephony always demand high-quality audio. In addition to users’ expectation, their emotional state, content type, and many other psychological factors; network quality of service; and distortions introduced at the end terminals could determine their quality of experience. To measure the quality experienced by the end user for voice transmission service, the E-model standardized in the ITU-T Rec. G.107 (a narrowband version), ITU-T Rec. G.107.1 (a wideband version), and the most recent ITU-T Rec. G.107.2 extension for the super-wideband E-model can be used. In this work, we present a quality of experience model built on the E-model to measure the impact of coding and packet loss to assess the quality perceived by the end user in WebRTC speech applications. Based on the computed Mean Opinion Score, a real-time adaptive codec parameter switching mechanism is used to switch to the most optimum codec bitrate under the present network conditions. We present the evaluation results to show the effectiveness of the proposed approach when compared with the default codec configuration in WebRTC.

scholarly journals Monitoring and characterization of vibration and shock conditions aboard high-performance marine craft

2018 ◽  
Vol 233 (4) ◽  
pp. 1068-1081
Author(s):  
Manudul Pahansen de Alwis ◽  
Karl Garme
Keyword(s):  
Real Time ◽  
High Speed ◽  
High Performance ◽  
Severity Index ◽  
Irregular Waves ◽  
Vibration Exposure ◽  
Data Set ◽  
Real Time Analysis ◽  
Impact Acceleration ◽  
The Impact

The stochastic environmental conditions together with craft design and operational characteristics make it difficult to predict the vibration environments aboard high-performance marine craft, particularly the risk of impact acceleration events and the shock component of the exposure often being associated with structural failure and human injuries. The different timescales and the magnitudes involved complicate the real-time analysis of vibration and shock conditions aboard these craft. The article introduces a new measure, severity index, indicating the risk of severe impact acceleration, and proposes a method for real-time feedback on the severity of impact exposure together with accumulated vibration exposure. The method analyzes the immediate 60 s of vibration exposure history and computes the severity of impact exposure as for the present state based on severity index. The severity index probes the characteristic of the present acceleration stochastic process, that is, the risk of an upcoming heavy impact, and serves as an alert to the crew. The accumulated vibration exposure, important for mapping and logging the crew exposure, is determined by the ISO 2631:1997 vibration dose value. The severity due to the impact and accumulated vibration exposure is communicated to the crew every second as a color-coded indicator: green, yellow and red, representing low, medium and high, based on defined impact and dose limits. The severity index and feedback method are developed and validated by a data set of 27 three-hour simulations of a planning craft in irregular waves and verified for its feasibility in real-world applications by full-scale acceleration data recorded aboard high-speed planing craft in operation.

Free Space Optical Communication System under Different Weather Conditions

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohammad Yawar Wani ◽  
Hitesh Pathak ◽  
Karamjit Kaur ◽  
Anil Kumar
Keyword(s):  
Attenuation Coefficient ◽  
Optical Communication ◽  
Free Space ◽  
Communication Systems ◽  
High Speed ◽  
Free Space Optical Communication ◽  
Free Space Optical ◽  
Wide Range ◽  
Space Optical Communication ◽  
The Impact

AbstractFree space optical communication systems (FSO’s) have surfaced as admired means of communication in the past few years. High speed of operation, low bandwidth requirements and system reliability are the major factors responsible for their wide range of applications. These communication systems use air as a medium of transmission. Since there is no component like fiber or cable, but air is only medium, the variations in atmospheric conditions play a vital role in performance of these networks. The reason behind is that the conditions like presence of humidity, haze, snowfall, rain, dust or smoke changes the attenuation coefficient of medium. The raised attenuation levels results in increased losses and need to be carefully monitored. The present work analyzes the influence of rain on the performance of FSO network in terms of quality of transmission. The paper discusses the impact of rainfall on attenuation coefficient of air. Then impact of this attenuation on network transmission is presented in terms of BER and Q-factor. In order to demonstrate the impact, BER and Q-value is calculated for 10 Gbps FSO link for clear weather and rainfall conditions.

scholarly journals 4D imaging of sub-second dynamics in pore-scale processes using real time synchrotron x-ray tomography

2016 ◽  
Author(s):  
Katherine J. Dobson ◽  
Sophia B. Coban ◽  
Sam A. McDonald ◽  
Joanna Walsh ◽  
Robert Atwood ◽  
...  
Keyword(s):  
Real Time ◽  
High Frequency ◽  
High Speed ◽  
Motion Blur ◽  
Transport Processes ◽  
Fluid Distribution ◽  
Pore Scale ◽  
X Ray ◽  
Wide Range ◽  
In Situ Experiments

Abstract. A variable volume flow cell has been integrated with state-of-the-art ultra-high speed synchrotron x-ray tomography imaging. The combination allows the first real time (sub-second) capture of dynamic pore (micron) scale fluid transport processes in 4D (3D + time). With 3D data volumes acquired at up to 20 Hz, we perform in situ experiments that capture high frequency pore-scale dynamics in 5–25 mm diameter samples with voxel (3D equivalent of a pixel) resolution of 2.5 to 3.8 µm. The data are free from motion artefacts, can be spatially registered or collected in the same orientation making them suitable for detailed quantitative analysis of the dynamic fluid distribution pathways and processes. The method presented here are capable of capturing a wide range of high frequency non equilibrium pore-scale processed including wetting, dilution, mixing and reaction phenomena, without sacrificing significant spatial resolution. As well as fast streaming (continuous acquisition) at 20 Hz, it also allows larger-scale and longer term experimental runs to be sampled intermittently at lower frequency (time-lapse imaging); benefiting from fast image acquisition rates to prevent motion blur in highly dynamic systems. This marks a major technical breakthrough for quantification of high frequency pore scale processes: processes that are critical for developing and validating more accurate multiscale flow models through spatially and temporally heterogeneous pore networks.

Telecardiology and its settings of application: An update

2017 ◽  
Vol 24 (5) ◽  
pp. 373-381 ◽  
Author(s):  
Giuseppe Molinari ◽  
Martina Molinari ◽  
Matteo Di Biase ◽  
Natale D Brunetti
Keyword(s):  
Real Time ◽  
Tertiary Care ◽  
Implantable Devices ◽  
Decision Making Process ◽  
Clinical Settings ◽  
Medical Specialties ◽  
Coronary Syndrome ◽  
Wide Range ◽  
Patients With Heart Failure ◽  
The Impact

Among the wide range of medical specialties in which telemedicine has been successfully applied, cardiology can be considered as one of the most important fields of application. Through the transmission of clinical data and the electrocardiogram, telecardiology allows access to a real-time assessment (teleconsultation) without any need to travel for both patient and cardiologist. This review discusses the impact of telecardiology in different clinical settings of application. Pre-hospital telecardiology has proved to be useful either in the clinical management of remote patients with acute coronary syndrome or in supporting the decision-making process of general practitioners. In the setting of in-hospital telecardiology, most of the applications refer to real-time echocardiography transmissions between rural small hospitals and tertiary care centres, particularly for the diagnosis or exclusion of congenital heart disease in newborns. Finally, many trials show that post-hospital telecardiology improves outcomes and reduces re-admissions or outpatient contacts in patients with heart failure, arrhythmias or implantable devices.

A New Architecture of LCD Driver of Rail-to-Rail Buffer with High Gain Wide Range

2010 ◽  
Vol 97-101 ◽  
pp. 3765-3768
Author(s):  
Shih Han Lin ◽  
Shu Jung Chen ◽  
Chih Hsiung Shen
Keyword(s):  
High Speed ◽  
High Gain ◽  
Driving Ability ◽  
Fully Differential ◽  
Rail To Rail ◽  
Wide Range ◽  
Lcd Driver ◽  
Additional Circuitry ◽  
Differential Pair ◽  
The Impact

A new modified CMOS buffer amplifier with rail-to-rail input and output range is proposed by TSMC 0.35μm 2P4M process at 3.3V supply. The technique adds dummy pairs to sense the common mode range of the input differential pair and adjusts the output current accordingly. The amplifier provides high gain for a wider range of output voltages. Design considerations for reducing the impact of the additional circuitry on the core are provided. The technique described can be adapted for use with traditional fully-differential rail-to-rail amplifiers, which performs 86.9dB ~92dB dc gain, 15 MHz unit-gain bandwidth, high driving ability with high slew rate under a 100pF capacitance and a 3kΩ series resistance loading. The simulation results indicate that the settling times of rising and falling edge are within 3.5μs. It is effective for a high resolution and high speed LCD driver.

scholarly journals Parallel Extraction Architecture for Information of Numerous Particles in Real-Time Image Measurement

2005 ◽  
Vol 17 (4) ◽  
pp. 420-427 ◽  
Author(s):  
Yoshihiro Watanabe ◽  
◽  
Takashi Komuro ◽  
Shingo Kagami ◽  
Masatoshi Ishikawa
Keyword(s):  
Real Time ◽  
High Speed ◽  
Image Measurement ◽  
Multiple Particles ◽  
Asynchronous Operation ◽  
Wide Range ◽  
Real Time Image ◽  
Fast Processing ◽  
Time Image ◽  
Extract Information

In this paper, we propose a new architecture that can extract information of numerous particles in an image at high-speed. Particle information means various characteristics obtained from image moments. The proposed architecture simultaneously extracts moments of multiple particles in parallel. This parallel extraction enables a significant reduction in the amount of calculation required. In addition, asynchronous operation allows fast processing. We believe that this architecture can obtain more information in real-time even at high frame rates than conventional processing, providing advantages in a wide range of applications, mainly for image measurement. This paper details our proposed architecture and reviews some results of its implementation in FPGA.

scholarly journals Low Complexity FFT Factorization for CS Reconstruction

2020 ◽  
Vol 9 (3) ◽  
pp. 438-442
Keyword(s):  
Real Time ◽  
High Speed ◽  
Performance Metrics ◽  
Matching Pursuit ◽  
Matrix Multiplication ◽  
Low Complexity ◽  
Orthogonal Matching Pursuit ◽  
Reconstruction Algorithms ◽  
Wide Range ◽  
Computationally Intensive

In this paper is presented a novel area efficient Fast Fourier transform (FFT) for real-time compressive sensing (CS) reconstruction. Among various methodologies used for CS reconstruction algorithms, Greedy-based orthogonal matching pursuit (OMP) approach provides better solution in terms of accurate implementation with complex computations overhead. Several computationally intensive arithmetic operations like complex matrix multiplication are required to formulate correlative vectors making this algorithm highly complex and power consuming hardware implementation. Computational complexity becomes very important especially in complex FFT models to meet different operational standards and system requirements. In general, for real time applications, FFT transforms are required for high speed computations as well as with least possible complexity overhead in order to support wide range of applications. This paper presents an hardware efficient FFT computation technique with twiddle factor normalization for correlation optimization in orthogonal matching pursuit (OMP). Experimental results are provided to validate the performance metrics of the proposed normalization techniques against complexity and energy related issues. The proposed method is verified by FPGA synthesizer, and validated with appropriate currently available comparative analyzes.

Numerical Modeling of Hydrodynamic Impact and Local Slamming Effects

2015 ◽  
Author(s):  
Ali Mohtat ◽  
Ravi Challa ◽  
Solomon C. Yim ◽  
Carolyn Q. Judge
Keyword(s):  
Numerical Method ◽  
Impact Velocity ◽  
High Speed ◽  
Impact Behavior ◽  
Analytical Prediction ◽  
Arbitrary Lagrangian Eulerian ◽  
Hydrodynamic Impact ◽  
Ale Formulation ◽  
Wide Range ◽  
The Impact

Numerical simulation and prediction of short duration hydrodynamic impact loading on a generic wedge impacting a water free-surface is investigated. The fluid field is modeled using a finite element (FE) based arbitrary Lagrangian-Eulerian (ALE) formulation and the structure is modeled using a standard Lagrangian FE approximation. Validation of the numerical method against experimental test data and closed form analytical solutions shows that the ALE-FE/FE continuum approach captures the impact behavior accurately. A detailed sensitivity analysis is conducted to study the role of air compressibility, deadrise angle, and impact velocity in estimation of maximum impact pressures. The pressure field is found to be insensitive to air compressibility effect for a wide range of impact velocities and deadrise angles. A semi-analytical prediction model is developed for estimation of maximum impact pressures that correlates deadrise angle, impact velocity, and a nonlinear interaction term that couples hydrodynamic effects between these parameters. The numerical method is also used to examine the intrinsic physics of water impact on a high-speed planing hull with the goal of predicting slamming loads and resulting motions.

Loading Rate Effect Investigation of Through-Hole-Mounted Solder Joints

2005 ◽  
Author(s):  
Frank Z. Liang ◽  
Larry M. Palanuk ◽  
Mike Gabriel
Keyword(s):  
Solder Joint ◽  
High Speed ◽  
Loading Rate ◽  
High Loading ◽  
Static Tests ◽  
Loading Rates ◽  
Wide Range ◽  
Load To Failure ◽  
The Impact ◽  
Through Hole

This paper presents two simple and unique tests to extract shock-level loading limits for eutectic and lead free solders. A wide range of loading rates, from quasi-static to high speed, was applied to a through-hole-mounted anchor assembly test coupon. The high speed shock tests were conducted on a drop shock table where the impacting velocities were derived through table input adjustments. The quasi-static tests were done using controlled hydraulic linear actuator with a load cell. As would be assumed, the dynamic load to cause solder joint failure was found to increase with higher loading rate. However, at such a high loading rate range, the impact velocity did not change the load to failure. This study leads to an interesting hypothesis that at high loading rates, the solder joint strain rate may not see a significant change as observed at low rates.

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