scholarly journals Prediction of Loudness Metrics at Very High Sampling Frequencies using Digital Filters

2021 ◽  
Author(s):  
Sriram Rallabhandi
Keyword(s):  
Digital Filters ◽  
High Sampling ◽  
Very High

scholarly journals High sampling rate thermistor string observations at the slope of Great Meteor Seamount

Ocean Science ◽  
2005 ◽  
Vol 1 (1) ◽  
pp. 17-28 ◽  
Author(s):  
H. van Haren ◽  
R. Groenewegen ◽  
M. Laan ◽  
B. Koster
Keyword(s):  
High Frequency ◽  
North Atlantic Ocean ◽  
Sampling Rate ◽  
Very High Frequency ◽  
High Sampling ◽  
High Sampling Rate ◽  
In Situ Calibration ◽  
Great Meteor Seamount ◽  
Very High

Abstract. A high sampling rate (1 Hz) thermistor string has been built to accommodate the scientific need to accurately monitor high-frequency and vigorous internal wave and overturning processes in the ocean. The thermistors and their custom designed electronics can register temperature at an estimated precision of about 0.001° C with a response time faster than 0.25 s down to depths of 6000 m. With a quick in situ calibration using SBE 911 CTD an absolute accuracy of 0.005° C is obtained. The present string holds 128 sensors at 0.5 m intervals, which are all read-out within 0.5 s. When sampling at 1 Hz, the batteries and the memory capacity of the recorder allow for deployments of up to 2 weeks. In this paper, the instrument is described in some detail. Its performance is illustrated with examples from the first moored observations, which show Kelvin-Helmholtz overturning and very high-frequency (Doppler-shifted) internal waves besides occasionally large turbulent bores moving up the sloping side of Great Meteor Seamount, Canary Basin, North-Atlantic Ocean.

scholarly journals High-Radix Formats for Enhancing Floating-Point FPGA Implementations

2021 ◽  
Author(s):  
Julio Villalba ◽  
Javier Hormigo
Keyword(s):  
Execution Time ◽  
Digital Filters ◽  
Dynamic Range ◽  
Floating Point ◽  
Input Output ◽  
Point Support ◽  
Point Representation ◽  
High Radix ◽  
The Cost ◽  
Very High

AbstractThis article proposes a family of high-radix floating-point representation to efficiently deal with floating-point addition in FPGA devices with no native floating-point support. Since variable shifter implementation (required in any FP adder) has a very high cost in FPGA, high-radix formats considerably reduce the number of possible shifts, decreasing the execution time and area highly. Although the high-radix format produces also a significant penalty in the implementation of multipliers, the experimental results show that the adder improvement overweights the multiplication penalty for most of the practical and common cases (digital filters, matrix multiplications, etc.). We also provide the designer with guidelines on selecting a suitable radix as a function of the ratio between the number of additions and multiplications of the targeted algorithm. For applications with similar numbers of additions and multiplications, the high-radix version may be up to 26% faster and even having a wider dynamic range and using higher number of significant bits. Furthermore, thanks to the proposed efficient converters between the standard IEEE-754 format and our internal high-radix format, the cost of the input/output conversions in FPGA accelerators is negligible.

Planar Velocity Measurements at 100 kHz in Gas Turbine Combustors With a Continuous Laser Source

2017 ◽  
Author(s):  
Marek Mazur ◽  
Philippe Scouflaire ◽  
Franck Richecoeur ◽  
Léo Cunha Caldeira Mesquita ◽  
Aymeric Vie ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Mie Scattering ◽  
Velocity Fields ◽  
Laser Source ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Gas Turbine Combustors ◽  
Planar Velocity ◽  
High Sampling ◽  
Very High

This work aims at presenting a novel approach to measure planar velocity in gas turbine combustors at very high sampling frequencies. For this purpose, a continuous wave laser is used in order to illuminate particles that are seeded into the flow. The Mie scattering images are acquired with a high-speed camera at 100 kHz with a constant time between each frame. The velocity fields are then obtained by applying classical PIV algorithms on successive particle scattering images. While this approach has been recently used in other research fields, such as aerodynamics or hydrodynamics, it is relatively new in combustion studies, where pulsed laser systems with higher power levels are usually preferred. The proposed technique is an economical and ergonomic solution to determine velocity fields at very high sampling frequencies. It is highly portable and safe and convenient to use and align. The main drawback is the long image exposure duration due to the low laser energy. This leads to a smearing effect of the captured particles and acts as a low-pass filter. It has the consequence that the PIV algorithm does not determine the displacement of “dots”, but of “traces”. The measurement technique is tested experimentally on a model gas turbine combustor at a laboratory scale. The test is performed in three steps: (1) The instantaneous velocity fields are analysed in order to verify, whether the flame topology is represented correctly. (2) The mean and RMS velocity fields that are obtained with the present technique are compared with those obtained by classic low speed PIV. (3) Instantaneous synthetic Mie scattering fields are generated from a large eddy simulation (LES) on a similar combustor to test the algorithms. The planar velocity fields are calculated from these images and compared for the two techniques. Finally, possible error sources of the new technique are discussed.

scholarly journals Significance of Logic Synthesis in FPGA-Based Design of Image and Signal Processing Systems

2008 ◽  
pp. 265-283 ◽  
Author(s):  
Mariusz Rawski ◽  
Henry Selvaraj ◽  
Bogdan J. Falkowski ◽  
Tadeusz Luba
Keyword(s):  
Signal Processing ◽  
High Performance ◽  
Digital Filters ◽  
Logic Synthesis ◽  
General Purpose ◽  
Digital Systems ◽  
Fir Filters ◽  
Distributed Arithmetic ◽  
Embedded Dsp ◽  
Very High

This chapter, taking FIR filters as an example, presents the discussion on efficiency of different implementation methodologies of DSP algorithms targeting modern FPGA architectures. Nowadays, programmable technology provides the possibility to implement digital systems with the use of specialized embedded DSP blocks. However, this technology gives the designer the possibility to increase efficiency of designed systems by exploitation of parallelisms of implemented algorithms. Moreover, it is possible to apply special techniques, such as distributed arithmetic (DA). Since in this approach, general-purpose multipliers are replaced by combinational LUT blocks, it is possible to construct digital filters of very high performance. Additionally, application of the functional decomposition-based method to LUT blocks optimization, and mapping has been investigated. The chapter presents results of the comparison of various design approaches in these areas.

scholarly journals SPEED-ACCURACY TRADE-OFFS IN COMPUTING SPATIAL IMPULSE RESPONSES FOR SIMULATING MEDICAL ULTRASOUND IMAGING

2001 ◽  
Vol 09 (03) ◽  
pp. 731-744 ◽  
Author(s):  
JØRGEN ARENDT JENSEN
Keyword(s):  
Ultrasound Imaging ◽  
Sampling Frequency ◽  
Medical Ultrasound ◽  
Impulse Responses ◽  
Medical Ultrasound Imaging ◽  
High Sampling ◽  
Trade Offs ◽  
Line Elements ◽  
Speed Accuracy ◽  
Very High

Medical ultrasound imaging can be simulated realistically using linear acoustics. One of the most powerful approaches is to employ spatial impulse responses. Hereby both emitted fields and pulse-echo responses from point scatterers can be determined. Also any kind of dynamic focusing and apodization can be incorporated, as has been done in the Field II simulation program. Here the transducer is modeled through a set of either rectangles, triangles, or bounding lines, so that any geometry can be simulated. The response from the transducer is found by summing the spatial impulse responses from the individual elements. One of the problems in using spatial impulse responses is the abrupt changes in the responses due to the sharp transducer boundaries. Sampling the responses directly therefore have to be done at very high sampling frequencies to keep the shape and energy of the response. The high sampling frequency is unnecessary in the final signals, since the transducers used in medical ultrasound are band limited. Approaches to reduce the sampling frequency are, thus, needed to make efficient simulation programs. Field II uses time integration of the spatial impulse responses using a continuous rather than discrete time-axis. This preserves the energy in the responses and makes it possible to make sub-sample interval delays for focusing. The paper discusses the consequence of the integration for the rectangular elements that uses an approximative calculation of the spatial impulse responses. Data for the accuracy as a function of sampling frequency is given, and it is shown how a sampling frequency of 100 MHz gives similar results to using 2 GHz sampling of the analytic solution for rectangular elements. The spatial impulse responses for the triangular and bounding line elements are found analytically, and an iterative integration routine has to be used. The Romberg integration routine is used, and the accuracy versus sampling frequency for bounding line is shown. An increased accuracy is attained for the lines compared to the rectangles, but the simulation times are significantly higher. Line elements should therefore, in this implementation, only be used very close to the transducer, and if a very high precision is needed in the calculation.

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