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1

Multichannel sparse spike deconvolution based on dynamic time warping

Zhao Xiaowei, Wang Shangxu, Yuan Sanyi, Cheng Liang, Cai Youjun

Acta Geophysica

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2021

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Vol. 69, no. 3

783--793

EN

Seismic sparse spike deconvolution is commonly used to invert for subsurface refectivity series and is usually implemented as an inversion scheme. Conventional sparse spike deconvolution method does not utilize the relationships among adjacent traces resulting in instability and poor lateral continuity of the inverted result. We propose a multichannel sparse spike deconvolution method with a sparsity-promoting constraint and an extra lateral constraint exploiting the spatial relationships among adjacent seismic traces. Firstly, the dynamic time warping (DTW) is performed between any two adjoining seismic traces to obtain the warping path (a series of estimated time shifts of one seismic trace relative to the other). Based on the assumption that if the inverted refectivity series is convolved with the same wavelet used for inversion, the newly constructed adjoining seismic traces shall also be conformable to the relationships exploited among the original seismic traces by DTW. A diference operator is constructed with the estimated time shifts to guarantee the diference operation is performed between corresponding time samples on adjoining seismic traces and the inversion is regularized with this diference operator as the lateral constraint. Synthetic and real data case studies confrm that inverted result obtained by the proposed method is superior to those obtained by single-channel sparse spike deconvolution method and another multichannel deconvolution method based on horizontal frst-order derivative constraint in both signal-to-noise ratio and lateral continuity.

2

Computer – aided method for lower limbs kinematic analysis

Ogiela Marek R., Hachaj Tomasz

Przegląd Elektrotechniczny

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2020

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R. 96, nr 6

15--25

EN

The aim of this paper is to propose a novel method that enables kinematic analysis of motion capture (MoCap) data of lower limbs activities by comparison of body joints trajectories to the reference template. We propose an appropriate human body kinematic model, MoCap aligning procedure and heuristic evaluation with Dynamic Time Warping (DTW) - based approach. In contrast to other state-of-the-art papers, where analysis is performed on the single joint on the selected two-dimensional plane, we performed three-dimensional evaluation of human body by analyzing the whole kinematic chain jointly. This approach allows us to find which body joints affected the difference between the input and reference recordings the most. This is valuable information that a person who evaluates MoCap data expects to find. We have also performed kinematic analysis applying commonly used kinematic parameters proposed in state-of-the-art researches in order to show that in our case, when there is no restriction on speed or dynamic of action to be analyzed, those parameters cannot be used to draw valuable conclusions. We have tested our method on a dataset consisting recordings of four karate athletes with various experience in Shorin Ryu karate school. While comparing our algorithm’s results to experts evaluation the true positive rate equals 0.93 while negative rate 0.96.

PL

W pracy zaproponowano nową metodę analizy kinematyki kończyn dolnych przy pomocy nagrań motion capture (MoCap). Zaproponowane rozwiązanie pozwala na kompleksową analize całosci łańcucha kinematycznego. Przetestowaliśmy zaproponowany algorytm na zbiorze danych zawierającym nagrania czterech zawodników Shorin Ryu karate uzyskując zadawalające wyniki w porównaniu do analogicznej ewaluacji przeprowadzonej przez eksperta.

3

Times series averaging and denoising from a probabilistic perspective on time-elastic kernels

Marteau Pierre-Francois

International Journal of Applied Mathematics and Computer Science

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2019

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Vol. 29, no. 2

375--392

EN

In the light of regularized dynamic time warping kernels, this paper re-considers the concept of a time elastic centroid for a set of time series. We derive a new algorithm based on a probabilistic interpretation of kernel alignment matrices. This algorithm expresses the averaging process in terms of stochastic alignment automata. It uses an iterative agglomerative heuristic method for averaging the aligned samples, while also averaging the times of their occurrence. By comparing classification accuracies for 45 heterogeneous time series data sets obtained by first nearest centroid/medoid classifiers, we show that (i) centroid-based approaches significantly outperform medoid-based ones, (ii) for the data sets considered, our algorithm, which combines averaging in the sample space and along the time axes, emerges as the most significantly robust model for time-elastic averaging with a promising noise reduction capability. We also demonstrate its benefit in an isolated gesture recognition experiment and its ability to significantly reduce the size of training instance sets. Finally, we highlight its denoising capability using demonstrative synthetic data. Specifically, we show that it is possible to retrieve, from few noisy instances, a signal whose components are scattered in a wide spectral band.

4

Towards the automatic acoustical avian monitoring system

Wielgat R., Król D., Potempa T., Kozioł P., Lisowska-Lis A.

Tarnowskie Colloquia Naukowe. Nauki Techniczne i Ścisłe

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2017

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T. 4, nr 3

17--38

EN

One of the crucial aspects of the environmental protection is continuous monitoring of environment. Specific aspect is estimation of the bird species population. It is particularly important for bird species being in danger of extinction. Avian monitoring programs are time and money consuming actions which usually base on terrain expeditions. Certain remedy for this can be automatic acoustical avian monitoring system, described in the paper. Main components of the designed system are: digital audio recorder for bird voices acquisition, computer program automatically recognizing bird species by its signals emitted (voices or others) and object-relational database accessed via the Internet. Optional system components can be: digital camera and camcorder, bird attracting device, wireless data transmission module, power supply with solar panel, portable weather station. The system records bird voices and sends the recordings to the database. Recorded bird voices can be also provoked by the attracting device. Application of wireless data transmission module and power supply with solar panel allows long term operation of digital sound recorder in a hard accessible terrain. Recorded bird voices are analysed by the computer program and labelled with the automatically recognized bird species. Recognition accuracy of the program can be optionally enhanced by an expert system. Besides of labelled sound recordings, database can store also many other information like: photos and films accompanying recorded bird voices/ sounds, information about localization of observation/ recordings (GPS position, description of a place of an observation), information about bird features and behaviour, meteorological information, etc. Database on the base of geographical/ geological digital maps can generate actual maps of bird population (presence, number of individuals of each species). Moreover data-base can trigger alerts in case of rapidly decreasing bird population. It is also possible to obtain new knowledge about bird species with data mining methods. The paper presents collected data on observed bird species (audio recordings, photos and films) as well as results of experiments testing particular components of the automatic acoustical avian monitoring system.

5

Wyszukiwanie podciągu w ciągu z zastosowaniem obiektów CRL

Barański M., Pelikant A.

Zeszyty Naukowe Wyższej Szkoły Informatyki

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2013

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Vol. 12, Nr 1

91--111

PL

Celem niniejszej pracy jest zaprezentowanie możliwości zastosowania mapowanych na elementy proceduralne Transact SQL klas obiektowych CLR tworzonych na platformie .NET w złożonych algorytmach przetwarzania. Przedstawione zostały podstawy teoretyczne algorytmów dopasowania łańcuchów dla alfabetów skończonych. Dla wprowadzonych alfabetów nieskończonych rozwiązania te nie mogą być w sposób prosty zmodyfikowane, dlatego zaproponowany został algorytm DTW (Dynamic Time Warping), który został oprogramowany z zastosowaniem reguł mapowania do obiektów rozszerzenia proceduralnego SQL. Przedstawiono elementy praktycznej realizacji praktycznej oraz dokonano omówienia wyników eksperymentu numerycznego dopasowującego gesty.

EN

The purpose of this work is to present the possibility to use mapped to the procedural elements Transact SQL CLR object classes that are created on the NET platform in a complex processing algorithms. There are presented theoretical algorithms for matching chains for finite symbol set alphabets. For introduced infinite symbol set alphabets solutions may not be easily modified, so it was proposed the algorithm DTW (Dynamic Time Warping), which was programmed using the mapping rules for procedural extension to SQL. There where shown elements of the practical implementation and the experimental results of matching gestures were discuss.