scholarly journals Device for Generating and Measuring Time Intervals

2019 ◽  
pp. 31-33
Author(s):  
I. Orobets ◽  
V. Shevchenko
Keyword(s):  
High Speed ◽  
Time Intervals ◽  
Reference Equipment ◽  
Measuring Devices ◽  
Frequency Counter ◽  
Additional Reference ◽  
Working Standards ◽  
Windows Xp ◽  
Generator Output ◽  
Electronic Commutator

The article suggests a device that extends the functionality of the measuring devices such as generators and frequency meters. So these devices can be used as part of working standards in a complex for verification and calibrating stopwatches. The device consists of an electronic commutator and a component controlled by a microcontroller, which forms the required intervals of time and provides a necessary connection from the generator output to the frequency counter input, turned on in the pulse counting mode. The control signal simultaneously arrives at the commutator and the device for automatic start/stop of stopwatches. The circuit design of the device allows minimizing the device’s influence on the overall metrological characteristics of the complex through the use of a high-speed controlled M74HC125 buffer (high-speed CMOS QUAD BUFFER (3-STATE)) as a switch. The M74HC125 buffer in this device is the only metrologically significant node; the state switching time of which in the aspect of this task can be ignored (Fig. 3). A computer and standard software, such as HyperTerminal from the Windows XP or PuTTY distribution, are used to control and communicate with the device. The device can be connected to the computer via USB. For laboratories that have these instruments in operation, this approach can help to avoid acquisitions of the additional reference equipment, which helps to reduce the maintenance and calibration costs of reference equipment.

Velocities of Starch Particles in ER Fluids Measured with Laser Speckle

2011 ◽  
Vol 287-290 ◽  
pp. 2781-2784
Author(s):  
Ji Jun Fan ◽  
Nan Hui Yu
Keyword(s):  
Electric Field ◽  
High Speed ◽  
Ccd Camera ◽  
Laser Speckle ◽  
Time Intervals ◽  
Sample Concentration ◽  
Speckle Patterns ◽  
The Mean ◽  
Er Fluids ◽  
Short Time

In this paper, the principle of measuring infinitesimal displacement by laser speckle is proposed to measure the velocities of particles in ER fluids. It is verified that speckles can be formed by illuminating laser beam on the starch ER fluids. The speckle patterns was recorded with high speed CCD camera, and the speckle patterns sequences with short time intervals was obtained by intercepting laser speckle video. Displacements parallel to the direction of electric field and that perpendicular to the direction of electric field were obtained by processing the two consecutive speckle patterns. The experimental results showed that the velocities of particles decreased oscillatorily with time. There is a critical electric field and a critical sample concentration, when lower than this critical electric field (concentration), the mean particle velocity increased; otherwise, it decreased.

Comparative Study of Ride Quality Measuring Devices

1998 ◽  
Vol 1643 (1) ◽  
pp. 125-135 ◽  
Author(s):  
Tahar El-Korchi ◽  
John Collura
Keyword(s):  
Comparative Study ◽  
New England ◽  
High Speed ◽  
Ride Quality ◽  
International Roughness Index ◽  
State Highway ◽  
Measuring Devices ◽  
New Construction ◽  
State Highway Agencies ◽  
Accuracy And Repeatability

State highway agencies (SHAs) in New England have an ongoing interest in providing the public with smoother rides. As an incentive to contractors, some SHAs include a bonus and penalty clause for new construction based on profile measurements and smoothness indices. These states are considering the use of high-speed profilers for profile measurements and quality control/quality assurance implementation. Therefore, an assessment of the accuracy and repeatability of these devices is essential. A comparative study of high-speed profilers owned by the New England SHAs was conducted in Worcester, Massachusetts. Two sites were profiled using the dipstick and the high-speed profiling devices. Statistical analysis of International Roughness Index measurements were used for evaluation of precision and bias, profiler speed, and sensor type. The repeatability for the profilers was good, especially for combined wheel paths (standard deviation between 0.016 and 0.079 m/km). The accuracy for the profilers varied depending on profiler type.

Experimental Analysis of a Bathtub Vortex in a Simplified Cowl Box of Automotive Vehicles

2012 ◽  
Author(s):  
Yann Recoquillon ◽  
Emmanuelle Andrès ◽  
Azeddine Kourta
Keyword(s):  
Vortex Structure ◽  
High Speed ◽  
Numerical Models ◽  
Contour Detection ◽  
Measuring Devices ◽  
Capacitance Probe ◽  
Controlled Flow ◽  
Set Up ◽  
Physical Phenomena ◽  
Bathtub Vortex

On automotive vehicles, the cowl box is a volume located at the bottom of the windshield, under the cowl top grille. It provides external fresh air to the HVAC (Heating, Ventilating and Air Conditioning) unit and it is used to collect water coming from the windshield under rain conditions. This box is designed as a tranquillisation chamber to segregate water from air and avoid the ingress of rainwater into the HVAC unit. However, as the area is awkward to access with measuring devices, our knowledge about the physics of flow in the cowl box is limited. The present work aims to advance our knowledge through experimental work on the air/water flow in a simplified cowl box in order to optimize the box size and improve numerical models. This paper will focus on the analysis of the bathtub vortex, which is potentially responsible for insufficient draining of the water collected in the cowl box. The experimental set-up consists of a Plexiglas parallelepiped representing a simplified cowl box with top cowl grille, HVAC inlet and drain. A blower generates airflow through the HVAC inlet. A water sheet, with controlled flow rate, is created on an inclined plane representing the windshield. Velocity measurements of all components are obtained by PIV (Particle Image Velocimetry) in the liquid phase and the surface level is recorded by a capacitance probe near the drain. Moreover, contour detection of the vortex core is achieved using a high-speed camera. Results show a relationship between the pressure loss generated by the airflow in the cowl box, the water level and the vortex structure. The modification of the vortex structure as well as the modification of velocity components near the air core are visible only in transient stages. These experimental results give us today some insight to understand the physical phenomena occurring in the cowl box.

Design and Realization of High Speed Data Transmission Based on PCI Bus of DM642

2012 ◽  
Vol 433-440 ◽  
pp. 3688-3691
Author(s):  
Bao Feng Zhang ◽  
Xiao Kun Chang
Keyword(s):  
Data Acquisition ◽  
High Speed ◽  
Data Transfer ◽  
Pci Bus ◽  
Bus Driver ◽  
Data Acquisition Card ◽  
High Speed Data ◽  
Transfer Method ◽  
Windows Xp ◽  
Speed Data Transmission

For realizing data acquisition and transmission based on PCI bus, a device driver was designed for data acquisition card, which use TMS320DM642 of TI and it’s PCI interface as transfer protocol. And in this development, we use VC++6.0, DDK and DriverStudio3.2 to develop the PCI bus driver for Windows XP, and realizing DMA high-speed data transfer method between data acquisition card and computer RAM.

REFRACTION ALONG A LAYER

Geophysics ◽  
1965 ◽  
Vol 30 (3) ◽  
pp. 369-388 ◽  
Author(s):  
T. W. Spencer
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Shear Mode ◽  
Ray Theory ◽  
Dominant Wavelength ◽  
Layer Depth ◽  
Time Intervals ◽  
Reflected Waves ◽  
Head Waves ◽  
Compressional Mode

High‐frequency geometric ray theory is used to investigate the refracted arrival from a high‐speed layer embedded in an infinite medium. The effect of changing the layer thickness to dominant wavelength ratio [Formula: see text] and the range to depth ratio (ρ/H) is analyzed for a point compressional source. The results approximate the exact solution when [Formula: see text]. The theory predicts shingling and shows that it is range‐limited. Factors which improve the resolution between reflected arrivals increase the range over which shingling occurs. As the range increases, the traveltime curves for all the multiply reflected rays which cross the layer the same number of times in the shear mode approach the same asymptote (regardless of the number of crossings in the compressional mode). When the layer is thick compared to the dominant wavelength, the refracted arrival may consist of a series of events separated by equal time intervals. Each event is produced by the superposition of reflected waves which cross the layer the same number of times in the shear mode. The amplitude of each event satisfies [Formula: see text], where H is the layer depth. Because the head waves decay like [Formula: see text], the reflected waves predominate at large ranges.

scholarly journals GRAIN-GRAIN INTERACTION IN OSCILLATING SHEETFLOW

1988 ◽  
Vol 1 (21) ◽  
pp. 53 ◽  
Author(s):  
W.T. Bakker ◽  
W.G.M. Van Kesteren ◽  
Z.H. Yu
Keyword(s):  
High Speed ◽  
Video Recordings ◽  
Measuring Devices ◽  
Ring Shear ◽  
Grain Interaction ◽  
Lateral Mixing ◽  
Ring Shear Apparatus ◽  
Neutrally Buoyant ◽  
Intrusion Depth

Viscous grain-grain interaction is an important aspect of the dynamics of oscillating sheetflow. This interaction between sand grains has been investigated qualitatively in a pulsating water tunnel. Furthermore, experiments concerning the interaction between neutrally buoyant spheres in a Couette flow have been carried out at a scale of 100:1 in a new developed ring shear apparatus, called " Carrousel." With respect to the dynamics of sheetflow, in-situ measuring devices for the sand concentration in the sheetflow ("Harp") and the bed load ("Swan") has been developed; some preliminary results are shown. For sand grains, the intrusion depth of sheetflow appears to be of the order of several mm. On high speed video recordings no lateral mixing between grain layers can be observed; for this some physical explanation is given. This supports the modelling of the sheetflow mechanism as moving grain layers.

scholarly journals Orthogonal Components Forming of the Microprocessor-Based Protection Input Signals

2020 ◽  
Vol 63 (4) ◽  
pp. 328-339 ◽  
Author(s):  
F. A. Romaniuk ◽  
V. Yu. Rumiantsev ◽  
Yu. V. Rumiantsev ◽  
V. S. Kachenya
Keyword(s):  
Fourier Transform ◽  
Discrete Fourier Transform ◽  
High Speed ◽  
Block Diagram ◽  
Short Circuit ◽  
Current Transformer ◽  
Secondary Current ◽  
Measuring Devices ◽  
Input Signals ◽  
Orthogonal Components

The use of orthogonal components (OS) is the main direction of determining information parameters in microprocessor relay protection and automation of electric power systems. Most of the measuring devices used in modern protection and automation devices can be implemented using known operating systems. Digital non-recursive frequency filters based on discrete Fourier transform are used for OS selection. The main disadvantage of these filters is their low performance that exceeds the period of industrial frequency. For the construction of high-speed measuring devices, this time of establishing the true output signal is often unacceptable. The article proposes to form the equivalent signal OS in microprocessor defenses based on the values of the cosine and sine axes of the main harmonic formed using a discrete Fourier transform, by multiplying them by a correction factor, which is a function of the values of the input signal amplitude and its main harmonic. The proposed algorithm for generating OS input signals in microprocessor defenses is characterized by high performance in transient modes and has wide functionality. A block diagram of an OS equivalent signal generator has been developed, all blocks of which can be implemented according to known schemes on a microelectronic and microprocessor element base. The OS shaper model is implemented in the MatLab-Simulink dynamic modeling environment. The model functioning was checked using two types of test actions, viz. a sinusoidal signal with a frequency of 50 Hz (idealized action) and a signal close to the real secondary current of a short-circuit current transformer. As a result of the performed calculations, a significant (up to two times) in the speed of the proposed method of OS formation in comparison with the formers based on the discrete Fourier transform, frequency properties of both formers being identical.

scholarly journals Global ground strike point characteristics in negative downward lightning flashes – part 1: Observations

2021 ◽  
Author(s):  
Dieter R. Poelman ◽  
Wolfgang Schulz ◽  
Stephane Pedeboy ◽  
Dustin Hill ◽  
Marcelo Saba ◽  
...  
Keyword(s):  
High Speed ◽  
Geometric Mean ◽  
Time Interval ◽  
Data Sets ◽  
Time Intervals ◽  
High Speed Video ◽  
Video Recordings ◽  
The World ◽  
Multiple Stroke ◽  
Interval Value

Abstract. Lightning properties of a total of 1174 negative downward lightning flashes are analyzed. The high-speed video recordings are taken in different regions around the world, including Austria, Brazil, South Africa and USA, and are analyzed in terms of flash multiplicity, duration, interstroke intervals and ground strike point (GSP) properties. Although the results vary among the data sets, the analysis reveals that a third of the flashes are single-stroke events, while the overall mean number of strokes per flash equals 3.67. From the video imagery an average of 1.56 GSPs per flash is derived, with about 60 % of the multiple stroke flashes striking ground in more than one place. It follows that the channel creating a GSP is re-used by a factor of 2.3. Multiple-stroke flashes last on average 371 ms, whereas the geometric mean (GM) interstroke interval value preceding strokes producing a new GSP is about 18 % greater than the GM value preceding subsequent strokes following a pre-existing channel. In addition, a positive correlation between the duration and multiplicity of the flash is presented. The characteristics of the subset of flashes exhibiting multiple GSPs is further examined. It follows that strokes with stroke order of two create a new GSP in 60 % of the cases, while this percentage quickly drops for higher order strokes. Further, the possibility to form a new channel to ground in terms of the number of strokes that conditioned the previous channel shows that approximately 88 % developed after the occurrence of only one stroke. Investigating the time intervals in the other 12 % of the cases when two or more strokes re-used the previous channel showed that the average interstroke time interval preceding a new channel is found to be more than twice the time difference between strokes that follow the previous channel.

USB2.0-Based Data Acquisition System

2011 ◽  
Vol 179-180 ◽  
pp. 415-420
Author(s):  
Hong He ◽  
Xiao Lun Zhang ◽  
Da Jian Zhang ◽  
Ming Feng Hou
Keyword(s):  
Data Acquisition ◽  
Real Time ◽  
High Speed ◽  
Data Acquisition System ◽  
Acquisition System ◽  
Data Loss ◽  
Transmission Control ◽  
Time Intervals ◽  
Data Acquisition Card ◽  
Application Programs

CY7C68013 data acquisition card generally connect GPIF with other peripherals through the external FIFO, not only increasing the device but getting poor real-time relatively. This paper, USB2.0-Based data acquisition system, solves this problem successfully. The system based on high-speed USB2.0 transmission control chip CY7C68013, uses GPIF connected A / D device directly. Calculate time intervals correctly, not only avoiding data loss, but also saving the FIFO memory and related connections, which greatly reduce costs. This paper describes how the GPIF connects to A / D chip as well as designing of firmware and application programs.

Sign in / Sign up

Export Citation Format

Share Document