| 1. |
- Carlson, Rolf, et al.
(författare)
-
The Study of Experimental Factors
- 2020. - 2
-
Ingår i: Comprehensive Chemometrics. - : Elsevier. ; , s. 251-285
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The article presents methods for the study of experimental factors. The use of Ishikawa diagrams as tools for identifying relevant experimental variables is discussed. The construction and evaluation of two-level factorial and fractional factorial designs are presented in detail. Statistical properties of such designs are discussed. It is shown how the use of t-statistics and confidence intervals as well as how cumulative Normal probability plots can be used to identify significant variables. The methods are illustrated by examples from chemical experiments.
|
|
| 2. |
- Ashraf, Asra, et al.
(författare)
-
Enabling High-speed Ultrasound Communication Through Thin Plates by Reverberation Suppression
- 2021
-
Ingår i: 2021 IEEE International Ultrasonics Symposium (IUS). - : IEEE.
-
Konferensbidrag (refereegranskat)abstract
- In all digital communications, knowledge of the propagation channel between the transmitter and the receiver is essential. For transmitting of data through solid bodies, such as metal plates, pipe walls, etc., ultrasound is a viable alternative to radio communication and wired transmission. In ultrasound communication, the channel consists of two parts, the combined response of the transducers used as transmitter and receiver, and the impulse response of the propagation medium itself. For a thin plate with parallel surfaces, this results in a reverberating channel that significantly reduces the achievable bitrate if not handled properly. In this paper we show with simulations how the bit-error rate in Orthogonal Frequency Division Multiplexing (OFDM) communications, is affected by the reverberating nature of the plate, and how this can be overcome by the introduction of a channel shortening filter placed in front of the OFDM conventional receiver. The results show that this significantly reduces the bit-error rate, especially for thin plates. If the reverberations instead were to be compensated by the conventional channel equalization method in OFDM, we show that for the example in the simulations, the bitrate would drop by almost 25 %, from about 3.9 Mbit/s to about 2.9 Mbit/s.
|
|
| 3. |
- Ashraf, Asra, 1989-, et al.
(författare)
-
The solid-body reverberating ultrasound communications channel and its OFDM interference
- 2022
-
Ingår i: 2022 IEEE Latin-American Conference on Communications (LATINCOM). - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- In this paper we present an analytical approach to the solid-state ultrasound communications channel. Channel reverberations and the long associated channel delay spreads pose the possibility that the channel length exceeds that of the moderate cyclic prefix in an orthogonal frequency division multiplexing (OFDM) system, resulting in intersymbol and intercarrier interference. We present a channel model based on the propagation material characteristics and evaluate the extent and impact of the intrinsic OFDM interferences. We derive an analytical expression and show with simulations that the intersymbol and intercarrier interference (ISI and ICI) are spectrally concentrated to the lower frequencies of the OFDM multiplex.
|
|
| 4. |
- Ashraf, Asra, et al.
(författare)
-
Ultrasound Communication Through Thin Plates: Understanding and Estimating the Channel
- 2022
-
Ingår i: 2022 IEEE International Ultrasonics Symposium (IUS). - : IEEE. - 9781665466578
-
Konferensbidrag (refereegranskat)abstract
- As with all digital communications, understanding the propagation channel is essential. In this paper we present an analytical model of a channel consisting of a thin plate, including effects of frequency-dependent speed of sound and attenuation. We show how a compressed sensing approach can be used to estimate this channel impulse response from real measurements, even for cases when the plate thickness causes the reverberating pulses to overlap. The estimate can be seen as a sparsity constrained deconvolution of the combined impulse responses of the transmitting and receiving transducers. We then show with simulations that the proposed sparsity-constrained estimate is able to cope also in the presence of dispersion. We also analyze the performance of the proposed method both with simulations and experiments on 6 mm and 2 mm thick glass plate and 3 mm thick aluminum plate, and our results show that the model assumptions seems to hold.
|
|
| 5. |
- Ashraf, Asra, 1989-
(författare)
-
Ultrasound Communication through Thin Plates: Understanding the Channel
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ultrasound, composed of sound waves with frequencies above the human audible range, has become widely used in various technological fields for digital communications. In the past, acoustic and ultrasonic waves were employed in military and commercial un-derwater wireless communication systems due to their superior performance compared to electromagnetic waves. Ultrasound has also emerged as a viable alternative to radio and wired transmission for data transmission through solid bodies like metal plates and pipe walls. Notably, ultrasound offers high-security features as it is nearly undetectable from outside the room, minimizing the risks of wireless interception and attacks like Bluesniping and jamming.In any digital communication system, understanding the propagation channel between the transmitter and receiver is crucial. The ultrasound communication channel comprises three main components: transmitting and receiving transducers and the medium through which the sound propagates. Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier scheme that divides the available spectrum into multiple non-overlapping subcarriers for digital communication.In the context of ultrasound communication, the channel consists of two parts: the combined response of the transducers used as the transmitter and receiver, and the im-pulse response of the propagation medium. When dealing with a thin plate with parallel surfaces, this results in a reverberating channel. The reverberating channel comprises a primary pulse along with echo pulses that possess similar shapes but decaying amplitudes. The amplitude decay occurs due to four prominent factors: power losses in the trans-ducers at each side, transmission losses at the boundaries of the plate and transducer, ultrasound pulse attenuation within the plate, and beam spreading as the ultrasound pulse travels over distance. The reverberations elongate the impulse response of the channel, thus require a long cyclic prefix to prevent data symbols to overlap. However, this limitation restricts the achievable bit rate and energy efficiency of the system.In this thesis, we present a model for the reverberating ultrasound channel suitable for various plate materials. We propose a novel system-level path loss model that accounts for losses at the transducers, transmission losses, material attenuation, and diffraction losses. Based on this model, we calculate a comprehensive link budget that explicitly considers plate thickness. Furthermore, we conduct a quantitative analysis to evaluate the impact of Inter-Symbol Interference (ISI) and Inter-Carrier Interference (ICI) on the performance of the OFDM system. Through computer simulations, we evaluate the system’s performance and demonstrate that for a metal plate with a thickness of 5 mm, an uncoded data rate of 32 Mbps can be achieved.
|
|
| 6. |
- Carlson, Johan E., 1973-
(författare)
-
Bringing an Old Topic to Life by Changing the Way it is Taught : Reinventing a course in Measurement Systems Engineering
- 2020
-
Ingår i: Bidrag från 7:e utvecklingskonferensen för Sveriges ingenjörsutbildningar. - : Luleå tekniska universitet. ; , s. 200-201
-
Konferensbidrag (refereegranskat)abstract
- This paper describes the ongoing work to reform teaching of (Electrical) Measurement Systems Engineering, in order to put more emphasis on the students as active learners, better prepared to take on responsibilities of a modern engineer. The paper describes how the development of generic engineering skills are incorporated in the context of the technical subject.
|
|
| 7. |
- Carlson, Johan E., 1973-, et al.
(författare)
-
High Resolution Image Reconstruction from Full-Matrix Capture Data Using Minimum Mean Square Error Deconvolution of the Spatio-Temporal System Transfer Function
- 2020
-
Ingår i: 2020 IEEE International Ultrasonics Symposium (IUS). - : IEEE.
-
Konferensbidrag (refereegranskat)abstract
- The resolution of ultrasound images generated withconventional delay-and-sum beamformers, such as for examplethe Total Focusing Method (TFM), is limited by the overall systemtransfer function (point-spread function). This limits, for examplethe minimum distance between defects that can be detectedwithout the defects showing up as one larger peak in the image.In this paper, we propose a technique based on modeling ofthe complete spatio-temporal transfer function of the imagingsystem, that efficiently suppresses this and thus increases theimage resolution substantially. The method is demonstrated withsimulations and compared with the TFM.
|
|
| 8. |
- Carlson, Johan E., 1973-, et al.
(författare)
-
Modeling of the Stress-Strain Relationship of Rock Bolts from Ultrasound Data
- 2021
-
Ingår i: 2021 IEEE International Ultrasonics Symposium (IUS). - : IEEE.
-
Konferensbidrag (refereegranskat)abstract
- Load-bearing structural elements such as rock bolts and reinforcing bars (rebar) are ubiquitously present in both mining industries and in infrastructure projects, for securing tunnel walls and ceilings. Being able to detect and localize defects in previously installed rock bolts, or even quantitatively estimate the load they are taking, would be very valuable when planning maintenance and service. Unfortunately, there are no such techniques available today. Previous work shows that ultrasound, being a mechanical wave, is sensitive to mechanical changes in rock bolts. The ultrasound signature is, however, rather complex, and traditional modeling of the wave propagation rapidly becomes challenging. In this paper, we show that the ultrasound signature measured from a 3.2 m long dynamic rock bolt can be used to accurately determine the load applied to the bolt and the resulting elongation of the bolt. The method is based on training a Partial Least Squares Regression (PLSR) model to estimate the force an elongation from power spectra of backscattered ultrasound signatures.
|
|
| 9. |
- Carlson, Johan E., 1973-, et al.
(författare)
-
Ulraljudsmetod för mätning av belastning på bergbultar : [Ultrasound Method for Measurement of Load on Rock Bolts]
- 2022
-
Konferensbidrag (refereegranskat)abstract
- Inom både gruvindustri och infrastrukturprojekt är tillståndskontroll av bergbultar av stort intresse. Det finns dedikerade mätbultar som kan installeras för att detektera och följa förändringar över tid. Det finns även metoder för att kontrollera ingjutningen av bultar vid installation. Däremot saknas idag mätmetoder för att följa tillståndet hos generiska bergbultar över tid, eller för att detektera avvikelser bland sedan tidigare installerade bultar.I detta projekt utvecklas en metod baserad på ultraljud för att följa förändringar i mekaniska egenskaper över tid och för att kunna detektera avvikande bultar i en population av redan installerade bultar. Metoden bygger på en kort ultraljudspuls skickas in i bulten från den fria änden och att en reflekterat ljud från hela bultens längd samlas in. Detta fingeravtryck av bulten kan sedan jämföras bultar emellan, eller följas för en enskild bult över tid.För att demonstrera principen visar vi hur uppmätta ultraljudssignaturer kan användas för att modellera hela dragprovskurvan (kraft mot töjning), från vila till brottgräns för en c:a 3 meter lång dynamisk bergbult.
|
|
| 10. |
- Gupta, Payal, et al.
(författare)
-
Deep Learning for Modeling of Sound Pressure Fields of Real-World Ultrasound Transducers
- 2022
-
Ingår i: 2022 IEEE International Ultrasonics Symposium (IUS). - : IEEE.
-
Konferensbidrag (refereegranskat)abstract
- There are several freely available toolboxes for modeling the sound pressure field of ultrasound transducers and transducer arrays (e.g., Field II, k-Wave, and DREAM, etc.). These model the beam patterns, or how the ultrasound pulse changes depending on where we observe it, i.e., they model the spatial impulse response of the transducers. Normally, the transmitted pulse is not modeled using these toolboxes, but instead it is assumed that this pulse shape is known. Also, the models are based on assumption of an ideal behavior of the transducers, which is not necessarily the case for a real-world transducers. As a consequence, fitting these models to real measurement data, in order for them to mimic the individual transducer available in the lab, is not generally not possible with any numerical accuracy. In this paper we show, instead, how a deep learning approach can be adopted to train a model that with numerical accuracy models an transducer individual. We compare the proposed technique with real measurements and models using the Field II toolbox and show that for the actual transducer at hand, the deep learning approach outperforms the results from Field II.
|
|
