High-speed Data Acquisition System Research Articles

Direct measurement of neutral/ion beam power using thermocouple analysis

Modern neutral beam injection systems such as those used on JET and MAST routinely use thermocouples embedded close to the surface of beam stopping elements, such as calorimeters and ion dumps, coupled to high-speed data acquisition systems to determine beam profile and position from temperature rise data. With the availability of low cost data acquisition and storage systems it is now possible to record data from all thermocouples in a fully instrumented calorimeter or ion dump on 10 ms timescales or better. This sample rate is sufficiently fast to enable the thermocouple data to be used to calculate the incident power density from 1D heat transfer theory. This power density data coupled with appropriate Gaussian fits enables the determination of the 2D beam profile and thus allows an instantaneous and direct measurement of beam power in real time. The theory and methodology required to analyse the fast thermocouple data from the MAST calorimeter and residual ion dump thermocouples is presented and direct measurements of beam power density are demonstrated. The power of desktop computers allows such analysis to be carried out virtually instantaneously. The methods used to automate this analysis are discussed in detail. A code, utilising the theory and methodology, has been developed to allow immediate measurements of beam power on a pulse by pulse basis. The uncertainty in determining the beam power density is shown to be less than 10%. This power density data is then fitted to a 2D Gaussian beam profile and integrated to establish the total beam power. Results of this automated analysis for the neutral beam and residual ion power of the MAST duopigatron are presented. This technology could be applied to a beam power safety interlock system. The application to a beam shine through protection system for the inner wall of the JET Tokamak is discussed as an example.

Smeared-Property Models for Shock-Impact Reliability of Area-Array Packages

Portable electronics is subjected to extreme accelerations in shock and drop impact. Product development cycle times and the cost constraints often restrict the number of design variations tested for drop robustness prior to identification of the final configuration. Simulation models capable of predicting transient dynamics can provide valuable insight into the design reliability under shock environments. In this study, explicit finite-element models have been used to study the transient dynamics of printed circuit boards during drop from 6ft. Methodologies for modeling components using smeared-property formulations have been investigated. Reduced integration element formulations examined include shell and solid elements. Model predictions have been validated with experimental data. Results show that models with smeared properties can predict transient-dynamic response of board assemblies in drop impact fairly accurately. High-speed data acquisition system has been used to capture in situ strain, continuity, and acceleration data in excess of 1×106samples∕s. Ultra-high-speed video at 40,000fps has been used to capture the deformation kinematics. Component types examined include plastic ball-grid arrays, tape-array ball-grid array, quad-flat-no-lead package, and conduction-cooled ball-grid array. Model predictions have been correlated with experimental data. Impact of experimental error sources on model correlation with experiments has been also investigated

Nondestructive sizing and localization of internal microcracks in fatigue samples

A large number of fatigue experiments on standardized samples is required for the development of databases of the fatigue properties of specific material systems. To facilitate such studies, different visual monitoring methods for surface fatigue cracks have been used; however, the problem of monitoring internal fatigue crack initiating during cold dwell fatigue of Ti is much more complicated. This paper describes the development and integration of several nondestructive evaluation methods for monitoring and sizing microcracks in titanium fatigue samples. For in situ monitoring of crack initiation and evolution ultrasonic Lamb wave signals are excited and acquired in the sample continuously during fatigue tests at different levels of fatigue load using a high-speed data acquisition system. Localization of the secondary cracks is done by both the in situ ultrasonic method and an ultrasonic immersion scanning method here referred to as “vertical C-scan” (VC-scan). The VC-scan is developed for imaging small cracks aligned normal to the fatigue sample axis. Microradiography has been performed on fatigue samples to confirm the localization and sizing of the detected cracks with other ultrasonic NDE techniques. The fusion of data from different NDE techniques provides useful information on the initiation, location, shape, size and growth history of fatigue cracks.

Mechanical Heart Valve Performance in a Pulsatile Pediatric Ventricular Assist Device

A pulsatile pediatric ventricular assist device with a dynamic stroke volume of 12 ml is currently under development at the Pennsylvania State University. A monoleaflet valve (Björk-Shiley Monostrut) and a bileaflet valve (CPHV, CarboMedics Prosthetic Heart Valve) were examined in this study. A high-speed video and data acquisition system was used to simultaneously record video images, pressure waveforms, and flow waveforms for an array of in vitro test conditions that varied heart rate and systolic duration. The CPHV in both the horizontal and vertical orientations have larger regurgitant volumes than the Monostrut valves at all operating conditions in both the inlet and outlet positions. However, the CPHV has higher stroke volumes and cardiac outputs than the Monostrut valve at higher heart rates and longer systolic durations. In addition, the hydrodynamic performance of the Monostrut valve is more sensitive to changes in operating conditions for the pulsatile pediatric ventricular assist device than the CPHV in both orientations. Additional testing is under way to identify the optimal operating conditions for each type of valve.

Design and implementation of high-speed real-time data acquisition system based on FPGA

The electromagnetic radiation will result in information leakage being recovered when computers work. This article presents a high-speed real-time data acquisition system based on peripheral component interconnect (PCI) bus and field programmable gate array (FPGA) for sampling electromagnetic radiation caused by video signal. The hardware design and controlling flow of each module are introduced in detail. The sampling rate can reach 64 Msps and system transfers speed can be up to 128 Mb/s by using time interleaving, which increases the overall sampling speed of a system by operating two data converters in parallel.

Impact Energy Measurement of a Hydraulic Breaker

A hydraulic breaker for construction machinery generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and so on. So the measurement of the impact energy of a hydraulic breaker is very important thing to prove its capability to manufacturers and customers. In this study, the test system for measuring the impact energy of a hydraulic breaker was designed and constructed. The test system was consisted with hydraulic cylinders for mounting a breaker, impact absorbing base and frames, pressure and flow sensors, high speed and accurate data acquisition system diesel engine driven hydraulic power unit. The test process of the developed system was carried by measuring guide for tool energy rating for hydraulic breakers which was developed by the CIMA (Construction Industry Manufacturers Association) USA. The developed test system can be applied to measure the impact energy for various kinds of hydraulic breakers.

Ethernet based list processing controller for high speed data acquisition systems

CAMAC standard crates and modules continue to be used for nuclear and high energy physics experiments and test setups. They provide unbeaten performance in high precision measurements, flexibility and simplicity in the design of modules. We have designed and fabricated a new type of CAMAC crate controller with list processing capability to maximize the data throughput, event rate handling capability, while simultaneously simplifying software development efforts for data acquisition systems, also maintain complete compliance with CAMAC standards and ability to utilize all existing CAMAC compliant modules. The throughput increase is achieved by eliminating the arbitration between the CAMAC crate controller and list processing modules by integrating the list processor (auxiliary crate controller) and the crate controller. The event rate handling capability is increased by advanced list processing techniques such as Q-stop and hit-pattern based list processing. The resulting ethernet based list processing crate controller can transfer up to 1700 kbytes/s reaching up to hundreds of kilo events̸s in 16bit transfer mode from CAMAC modules measured at the analysis engine end. This makes it suitable for use in experimental systems, where a large number of signals with high event rates need to be collected with high precision.

Models for Reliability Prediction of Fine-Pitch BGAs and CSPs in Shock and Drop-Impact

Drop-induced failures are most dominant in portable electronic products. In this study, explicit finite element models have been used to predict the transient dynamic behavior of various area-array package architectures assembled to printed circuit boards after drop-impact. Parameters predicted include field-quantities and their derivatives including displacement and strain. Methodologies for modeling components using smeared property formulations have been investigated. Reduced integration element formulations examined include—shell and solid elements. Model predictions have been validated with experimental data. Results show that models with smeared properties can predict transient-dynamic response of board assemblies in drop-impact, fairly accurately. A high-speed data acquisition system has been used to capture in-situ strain, continuity, and acceleration data in excess of 1 million samples per second. Ultra high-speed video at 40 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$thinspace$</tex> 000 fps has been used to capture the deformation kinematics. Component types examined include—plastic ball-grid arrays (BGAs), tape-array BGA, quad-flat no-lead packages (QFN), and conduction-cooled ball-grid arrays (C2BGA). Model predictions have been correlated with experimental data. Impact of experimental error sources on model correlation with experiments has also been investigated.

Performance evaluation of a dental handpiece in simulation of clinical finishing using a novel 2DOF in vitro apparatus

This paper reports on the performance evaluation of a dental handpiece in simulation of clinical finishing using a novel two-degrees-of-freedom (2DOF) in vitro apparatus. The instrumented apparatus consisted of a two-dimensional computer-controlled coordinate worktable carrying a dental handpiece, a piezoelectric force dynamometer, and a high-speed data acquisition and signal conditioning system for simulating the clinical operations and monitoring the dental finishing processes. The performance of the dental handpiece was experimentally evaluated with respect to rotational speed, torque, and specific finishing energy under the applied clinical finishing conditions. The results show that the rotational speeds of the dental handpiece decreased by increasing either the depth of cut or the feed rate at a constant clinically applied air pressure and water flowrate. They also decreased when increasing both the tangential and normal finishing forces. The specific finishing energy decreased with an increase in either depth of cut or feed rate, while the finishing torque increased as either the depth of cut or the feed rate was increased. Implications of these results were to provide guidance for proper applications of dental handpieces in clinical practice.

DEVELOPMENT OF SEMI-VLBI SYSTEM AND OBSERVATION OF SUN AT 21 cm

We report the development of a semi-VLBI observation system operating at 21 cm and present the measurement of visibility function toward the sun using this system. The system consists of two 2.3 meter antennas with a maximum separation of 35 meter, a conventional high speed data acquisition system, and a set of programs for software correlation. Since two local oscillators of receiver modules are independent, data had to be fringe-fitted to yield the visibility amplitude. It is found that the visibility amplitude decreases and then bounces back as baseline increases. We confirm that solar disk with brighter limb best explains the measured visibility amplitude.

A Simple Low-Cost Electrical Switching Analyzer for&amp;lt;tex&amp;gt;$I$&amp;lt;/tex&amp;gt;–&amp;lt;tex&amp;gt;$V$&amp;lt;/tex&amp;gt;Characterization of Switching Samples and Devices

The phenomena of nonlinear I-V behavior and electrical switching find extensive applications in power control, information storage, oscillators, etc. The study of I-V characteristics and switching parameters is necessary for the proper application of switching materials and devices. In the present work, a simple low-cost electrical switching analyzer has been developed for the measurement of the electrical characteristics of switching materials and devices. The system developed consists of a microcontroller-based excitation source and a high-speed data acquisition system. The design details of the excitation source, its interface with the high-speed data acquisition system and personal computer, and the details of the application software developed for automated measurements are described. Typical I-V characteristics and switching curves obtained with the system developed are also presented to illustrate the capability of the instrument developed.

Precombustion Chamber NOx Emission Contribution to an Industrial Natural Gas Engine

This work expands the knowledge base concerning the formation of oxides of nitrogen (NO x) in the precombustion chamber (PCC) of a four-stroke lean burn (4SLB) industrial gas engine. Two analysis methods were used to characterize specific exhaust constituent concentrations formed in the PCC. The first method extracted gas from the PCC and the overall engine exhaust to be analysed by the industry standard five gas rack (THC, NO x, O 2, CO 2, and CO) and a Fourier transform infrared spectrometer (FTIR) to quantify formaldehyde (CH2O), nitric oxide (NO), and nitrogen dioxide (NO2) concentrations. This paper focuses only on NO x. The engine was operated at the manufacturer's recommended conditions and at the engine's lean limit. A PCC air-fuel ratio (A/F) map was performed at each engine operating condition by varying the fuel supply pressure to the PCC. An analytical model was developed to estimate the mass flow between the PCC and main cylinder, and mass flow out of the PCC through a sample extraction apparatus. The model was applied at specific instances during the engine cycle to clarify raw emissions data obtained directly from a cylinde's PCC. The model was developed to determine the origin of the mass sampled from the PCC which, in turn, was used to correct the measured pollutant concentrations. The corrected concentrations allowed for a comparison between NO x, emissions formed in the PCC and the overall engine exhaust on a mass specific basis. PCC-formed NO x, were found to constitute ε10 per cent while operating at the manufacture's recommended conditions and upwards of ε75 per cent when at the lean limit. The second test method utilized the high-speed chemiluminescence capabilities of a Cambustion fNOX400 analyser to measure NO concentration in gas extracted from the PCC on a half crank angle basis. The intra-cycle NO data were recorded simultaneously with pressure traces from the PCC and main cylinder by a Hi-Techniques combustion analysis system. The high-speed data acquisition system provided qualitative information on both intra-cycle NO concentrations and cycle-to-cycle variations.

A Novel On-Chip Diagnostic Method to Measure Burn Rates of Energetic Materials

ABSTRACT A novel on-chip diagnostic method has been developed to measure burn rates of energetic materials patterned on a 1 inch × 3 inch glass chip. The method is based on time-varying resistance (TVR) of a sputter-coated thin platinum (Pt) film, in which resistance of the film changes because of the propagation of ignition of the nanoenergetic material over it. The corresponding voltage differential is captured by a high-speed data acquisition system (1.25 × 106 samples/s). We have measured burn rates as high as 504 m/s for thermites of copper oxide (CuO)/aluminum (Al) and 155 m/s for bismuth oxide (Bi2O3)/Al nanoparticles using this method. We have provided an explanation for the change of resistance upon ignition, based on the microstructural characterization and energy dispersive spectroscopy.

High-speed data acquisition system for neutron time-of-flight experiments

A high-speed data acquisition system comprising two parallel metering channels has been developed for neutron time-of-flight measurements. Each metering channel is equipped with a flash-ADC. The first channel is intended for measuring fast neutrons, whose energy ranges from tens of eV up to several keV, and uses a 40 MHz sampling rate. The second channel is intended for measuring slow neutrons, whose energy ranges down to several tenths of eV, and uses a 4 MHz sampling rate. Laboratory tests using the developed system have been performed and the system's efficiency dependence on the incoming counting rate has been obtained. As a result of this new design, the performance of the data acquisition system has increased by about an order of magnitude in comparison with existing systems. The designed data acquisition system is now used for the measurement of neutron capture cross-sections in a wide neutron energy range by a time-of-flight method.

A high-speed data acquisition system for ECT based on the differential sampling method

A new capacitance measuring circuit based on differential sampling methods for electrical capacitance tomography has been developed. The measured capacitance is only charged and discharged once and no noise is created by the measurement principle. A capacitance measurement system for 12 electrodes is constructed based on the new measurement circuit. Test results show the data acquisition time for 66 capacitances (for reconstructing one image) is less than 1.25 ms.

Start-up and steady thermal oscillation of a pulsating heat pipe

As a novel electronic cooling device, pulsating heat pipes (PHPs) have been received attention in recent years. However, literature survey shows that no studies were carried out on the start-up and steady thermal oscillation of the PHPs. In the present paper, the copper capillary tube was being bended to form the snake-shaped PHP. Heating power was applied on the heating section, and transferred to the condensation section and dissipated to the environment by the pure natural convection. The inside diameter of the capillary tube is 2.0 mm and the working fluid is selected as FC-72. A high speed data acquisition system was used to detect the start-up and steady thermal oscillation of the PHP. Two types of the start-up process were observed: a sensible heat receiving start-up process accompanying an apparent temperature overshoot followed by the steady thermal oscillation at low heating power, and a smooth sensible heat receiving start-up process incorporating a smooth oscillation period at high heating power. For the steady thermal oscillation, also two types were found: the random thermal oscillation with a wide frequency range, indicating the random distribution of the vapor plug and liquid slug inside the capillary tube at low heating power, and the quasi periodic thermal oscillation with the same characteristic frequency for both heating section and condensation section, indicating the uniform distribution of the vapor plug and liquid slug inside the capillary tube at high heating power. The power spectral density (PSD) was used to analyze the thermal oscillation waves. The frequency corresponds to the time that a couple of adjacent vapor plug and liquid slug passing through a specific wall surface.

Ultra-sensitive high-speed density measurement of the “piston effect” in a critical fluid

In order to conduct a detailed investigation of the piston effect, the peculiar heat transportation phenomenon in critical fluids, an ultra-sensitive high-speed density measurement system was developed using a very thin heater, a sensitive interferometer and a large-capacity high-speed data acquisition system. As the first step of the investigation, an experiment was conducted to measure the velocity of sound in CO2 near its critical point. Short heat pulses suppressing the disturbance of natural convection were applied to a small cell filled with almost-critical CO2 fluid and were detected by the measurement system. Because the pulses propagated through the cell at the velocity of sound and were reflected several times between the cell walls, the velocity could be precisely determined by measuring the time intervals between successive reflections. The resulting velocity profile versus temperature showed good agreement with theoretical prediction and numerical simulations. This result validated the density measurement system, and it is considered that the measurement system will be a very effective tool for further studies on critical phenomena with the aid of numerical simulation.

Characteristic modes and evolution processes of shear-layer vortices in an elevated transverse jet

Characteristics and evolution processes of the traveling coherent flow structure in the shear layer of an elevated round jet in crossflow are studied experimentally in an open-loop wind tunnel. Streak pictures of the smoke flow patterns illuminated by the laser-light sheet in the median and horizontal planes are recorded with a high speed digital camera. Time histories of the instantaneous velocity of the vortical flows in the shear layer are digitized by a hot-wire anemometer through a high-speed data acquisition system. By analyzing the streak pictures of the smoke flow visualization, five characteristic flow structures, mixing-layer type vortices, backward-rolling vortices, forward-rolling vortices, swing-induced mushroom vortices, and jet-type vortices, are identified in the shear layer evolving from the up-wind edge of the jet exit. The behaviors and mechanisms of the vortical flow structure in the bent shear layer are prominently distinct in different flow regimes. The frequency characteristics, Strouhal number, power-spectrum density functions, autocorrelation coefficient, as well as the time and length scales of the coherent structure and the Lagrangian integral scales are obtained by processing the measured instantaneous velocity data. The Strouhal number is found to decay exponentially with the increase of the jet-to-crossflow momentum flux ratio. The autocorrelation coefficients provide the information for calculating the statistical time scales of the coherent structure and the integral time scales of turbulence fluctuations. The corresponding length scales of the vortical structure and the integral length scales of turbulence in the shear layer are therefore obtained and discussed.

Full-Scale Experimental Measurement of Barge Impact Loads on Bridge Piers

Bridges that span navigable waterways must be designed to resist potential impact loads associated with barge or ship collisions. Despite this fact, few experimental data have been collected about the magnitude and nature of such loads. Vessel-impact components of bridge design specifications, such as the AASHTO bridge design provisions, are therefore based on limited experimental data. Recently, a bridge in the United States (Florida) was replaced with a new structure and thus afforded a unique opportunity to conduct full-scale barge impact tests on piers of the preexisting structure before it was demolished. Tests were conducted on two piers with fundamentally different types of foundation systems. Tests on one pier also were repeated in two structural configurations (with the superstructure present and then with it removed). In each test, instrumentation and high-speed data acquisition systems were used to quantify the dynamic loads generated during controlled collision events. Experimental procedures used during the tests are described, and selected test results are presented, including experimentally measured dynamic impact loads and associated barge deformations. Comparisons are then presented between experimentally collected data and the current AASHTO barge impact bridge design provisions.

Part 2: Design of Foundations and Structures: Full-Scale Experimental Measurement of Barge Impact Loads on Bridge Piers

Bridges that span navigable waterways must be designed to resist potential impact loads associated with barge or ship collisions. Despite this fact, few experimental data have been collected about the magnitude and nature of such loads. Vessel-impact components of bridge design specifications, such as the AASHTO bridge design provisions, are therefore based on limited experimental data. Recently, a bridge in the United States (Florida) was replaced with a new structure and thus afforded a unique opportunity to conduct full-scale barge impact tests on piers of the preexisting structure before it was demolished. Tests were conducted on two piers with fundamentally different types of foundation systems. Tests on one pier also were repeated in two structural configurations (with the superstructure present and then with it removed). In each test, instrumentation and high-speed data acquisition systems were used to quantify the dynamic loads generated during controlled collision events. Experimental procedures used during the tests are described, and selected test results are presented, including experimentally measured dynamic impact loads and associated barge deformations. Comparisons are then presented between experimentally collected data and the current AASHTO barge impact bridge design provisions.