Naturally weighted measurement data in power grid – measurement data in Fourier domain

The latest development of stochastic digital measurement method allows extremely simple measurement of Fourier coefficients and, thus, the harmonic amplitudes: the natural weights of the measurement data in Fourier domain. The significance of each measurement data is defined by its weight, which allows the optimization of data recording, data analysis and artificial neural network training in a power grid

Measurement in Fourier domain – a Natural Method of Big Data Volume Reduction

The paper presents an idea of a measurement in a Fourier domain by a means stochastic digital measurement method (SDMM) as a natural and logical way to reduce the amount of big data in for processing in real time. The measurement method is explained and its application to the power and energy measurements in the power grid is briefly described

Stochastic Digital Measurement Method and Its Application in Signal Processing

Classical measurement approach is often described as a process of discretizing an analogue signal in order to easily process it in some type of digital signal processor. Although this approach has been considered to be universally applicable, practical experience has shown that some signals (e.g. fast and/or noisy signals) cannot be always precisely measured. To overcome this problem, in the late 1990s, a new measurement approach called stochastic digital measurement method (SDMM) was presented. At the beginning, this method was intended for high-precision measurements of the integral (the mean value) of a product of two signals. However, in the late 2000s, it was shown that SDMM can be used to compute the Discrete Fourier Transform (DFT). Compared to the classical DFT/FFT processors, SDMM-based ones have two important advantages: first, they are much simpler and cheaper to implement, and second, they allow us to compute individual DFT components either in isolation or in parallel. This chapter is a review of the evolution of SDMM with a special emphasis on a two-bit SDMM. Topics covered include: theoretical foundations of SDMM, the architecture of SDMM-DFT processor and an example of prototype instrument used in power grid networks.This is the peer-reviewed version of the chapter: Radonjić, A., Sovilj, P., Đorđević Kozarov, J., Vujičić, V., 2019. Stochastic Digital Measurement Method and Its Application in Signal Processing, in: Advances in Engineering Research. Volume 27. Nova Science Publishers, Hauppauge, pp. 169–190. ISBN 978-1-5361-4803-

Measurement of event-related potentials and placebo

ERP is common abbreviation for event-related brain potentials, which are measured and used in clinical practice as well as in research practice. Contemporary studies of placebo effect are often based on functional neuromagnetic resonance (fMRI), positron emission tomography (PET), and event related potentials (ERP). This paper considers an ERP instrumentation system used in experimental researches of placebo effect. This instrumentation system can be divided into four modules: electrodes and cables, conditioning module, digital measurement module, and PC module for stimulations, presentations, acquisition and data processing. The experimental oddball paradigm is supported by the software of the instrumentation. [Projekat Ministarstva nauke Republike Srbije, br. TR32019 and Provincial Secretariat for Science and Technological Development of Autonomous Province of Vojvodina (Republic of Serbia) under research grant No. 114-451-2723

Measurement of event-related potentials and placebo

ERP is common abbreviation for event-related brain potentials, which are measured and used in clinical practice as well as in research practice. Contemporary studies of placebo effect are often based on functional neuromagnetic resonance (fMRI), positron emission tomography (PET), and event related potentials (ERP). This paper considers an ERP instrumentation system used in experimental researches of placebo effect. This instrumentation system can be divided into four modules: electrodes and cables, conditioning module, digital measurement module, and PC module for stimulations, presentations, acquisition and data processing. The experimental oddball paradigm is supported by the software of the instrumentation

ERP correlates of placebo and 'anti-placebo' effects

U ovom istraživanju bavili smo se neuralnim korelatima efekata placebo i 'anti-placebo' poruka putem merenja moždanih talasa (ERP). Umjesto uobičajenog termina nocebo, koristili smo termin 'anti-placebo', budući da poruke koje smo zadavali ispitanicima nisu trebale da proizvedu negativne efekte, već da umanje ili ponište efekat placeba. Primenili smo termalnu draž intenziteta 45 stepeni Celzijusa na kožu podlaktice. Ukupno je 29 studenata uzelo učešća u četiri eksperimentalne situacije: bez analgezije, nakon primene analgezije (korišćenjem EMLA kreme), nakon primene neutralne kreme koja je prezentovana kao analgetik (placebo situacija) i nakon primene EMLA kreme koja je prezentovana kao herbalna krema koja nije zvanično prihvaćena kao medikament ('anti-placebo' situacija). Neposredno nakon stimulacije, od ispitanika je zatraženo da procene nivo neprijatnosti na subjektivnoj skali osetljivosti 1-10, a nakon toga im je zadat kognitivni eksperiment, tokom koga su mereni ERP odgovori. Rezultati su pokazali tri glavna ERP efekta. U ranom efektu, sve tri eksperimentalne situacije koje su podrazumevale primenu anelgezije (tj. dve situacije sa farmako-anelgezijom + situacija sa placebo-aneglezijom) pokazale su različite profile ERP efekata u odnosu na situaciju u kojoj nije primenjena anelgezija. Ovaj rezultat smo interpretirali kao rano očekivanje da bilo koja vrsta anelgezije (uključujući placebo) treba da proizvede nekakav efekat, za razliku od situacije u kojoj nije bilo primene analgezije. Središnji ERP efekat je demonstrirao duže trajanje ERP efekata u situaciji sa 'anti-placebom' i u situaciji bez analgezije, dok su u situaciji sa primenom analgezije i u placebo situaciji ovi efekti bili mnogo kraci. Ovaj nas je rezultat naveo na zaključak da, na neuralnom planu, sugerisanje da je neki lek 'anti-placebo' proizvodi sličan profil ERP ili sličnu mentalnu aktivnost kao u situaciji bez leka. Ovaj rezultat poziva na preispitivanje preporuka lekara da neki lekovi nisu baš dobri, jer ovakve sugestije mogu potencijalno i nesvesno da umanje inače pozitivan efekat koji placebo ima tokom tretmana. Na kraju, u poznom efektu smo takođe uočili razlike između četiri eksperimentalne situacije, ali su ove razlike u vezi sa redosledom izlaganja eksperimentalnih situacija, te smo ih interpretirali kao artefakt eksperimentalnog dizajna.In the study we observed the effects of placebo and ''anti-placebo' messages on the neural activities registered through the event related potentials (ERP). Instead of commonly used term nocebo, we used the term 'anti-placebo', given that the message we delivered was not supposed to induce the negative effects, but just to diminish the effect of placebo. Thermal stimulus of 45 degrees of Celsius was applied on the skin of 29 students in a four different experimental situations: without analgesia, after receiving dermal analgesic EMLA Cream, after receiving neutral skin cream presented as an analgesic (placebo situation), and after receiving again EMLA Cream, but presented as the herbal analgesic not officially accepted as a medicament ('anti-placebo' situation). Immediately after stimulation, participants were asked to estimate the level of 'unpleasantness' of the stimuli on the subjective scale ranging from 1-10, and to start a cognitive experiment, during which the ERP responses were measured. Results showed three main ERP effects. In the early effect, we noticed that all three experimental situations with analgesia (that is, two conditions with the pharmaco-analgesia + the condition with the placebo analgesia) showed a different ERP effects in comparison to the condition with no analgesia. We interpreted these results as early expectancies that any analgesic (including placebo) should produce some effect in comparison to no-analgesic condition. In the medium effect, we observed significantly longer durations of the ERP effects in the situation of the 'anti-placebo' and no-analgesia, whereas in the analgesia and placebo condition these effects were much shorter. This result led us to the conclusion, that on the neural level, our suggestion of 'bad medicament' (similar to situation of no-medicament) caused a specific mental activity registered on ERP This effect is the one which calls into a question doctors' recommendations (which contain negative connotation) of medicaments, as they could potentially and unconsciously diminish a valuable impact that the placebo could have during a treatment. Finally, in the late effect, we also observed significant differences across the four experimental conditions, but these differences were directly correspondent with the order of presentation of experimental situations, and we interpret them as an artefact of the experimental design

Stochastic two-bit on-line temperature measurement with RTD Pt-100 sensor operating in a nonlinear mode

The paper proposes a method and device for on-line temperature measurement with Pt-100 sensor operating in a nonlinear mode. The sensor measures the temperature in range of 00C to 2000C, whereas the measured data are processed by applying a two-bit stochastic digital measurement method. The proposal is theoretically analyzed and tested experimentally. It is shown that the accuracy of the method depends on the accuracy of the sensor. At a sampling frequency of 1 MHz, the maximum accuracy is reached in 17.5 sec. and is equal to 0.015% of full scale (FS). On the other hand, when the measurement time interval is 0.1 sec. (the shortest measurement interval), the accuracy is equal to 0.1% of FS. Therefore, the proposed device can be used for both calibration and measurement purposes

Influence of rotational speed on the electrical and mechanical properties of the friction stir spot welded aluminium alloy sheets

An efficient and productive joining technique to weld aluminium has become a priority challenge for promoting the use of aluminium in the electrical industry. One of the challenges is to obtain welds with superior mechanical properties with the consistent quality of weld surface as well as low electrical resistance. In this paper, the influence of rotational speed during the friction stir spot welding of AA 5754-H111 was studied to analyse the mechanical and electrical properties of the welds. The results from two rotational speeds (1000 rpm and 4500 rpm) are presented and compared to the base material. It was observed that the samples welded at 1000 rpm showed a higher average shear failure load (~ 1.1 kN) compared to the samples welded at 4500 rpm (~ 0.94 kN). The microhardness of the samples welded at 1000 rpm was higher than that of the base material, while the microhardness of samples welded at 4500 rpm was lower. It was also found that the friction welded sheets, regardless of the rotational speed used, showed increased electrical resistance compared to the base material, albeit this increase for the samples welded at 1000 rpm was about 42%, compared to samples welded at 4500 rpm where this increase was just 14%

Grid fundamental harmonic measurement in presence of Gaussian frequency deviation using 2-bit flash A/D converter

U radu se predlaže novi pristup mjerenju osnovnog harmonika mrežnog napona i/ili struje, pomoću stohastičke digitalne mjerne metode i 2-bitnih flash A/D konvertera. Utvrđeno je da je varijacija mrežne frekvencije u Europskoj interkonekciji Gaussova. Podrobno je ispitan utjecaj poremećaja frekvencije na rezultate mjerenja osnovnog harmonika. Kako su teorijske analize iznimno složene zbog velike nelinearnosti i stohastičke prirode problema, simulacijska analiza se koristi kao primarna metoda za brzo ispitivanje i potvrđivanje hipoteze rada. Rezultati realističnih simulacija daju mjerne nesigurnosti ispod 0,01 % i 0,013 % za mjerene mrežne napone i struje, respektivno. Provedena je eksperimentalna provjera, usporedbom mjerenja komercijalnog instrumenta i mjerenja prototipa instrumenta koji se temelji na SDMM metodi. Utvrđeno je da su rezultati u skladu.The paper proposes a novel approach to the measurement of the power grid voltage and/or current fundamental harmonic, using stochastic digital measurement method (SDMM) and 2-bit flash A/D converters. The power grid frequency variation in the European interconnection has been found as Gaussian. The influence of the frequency disturbance on the results of fundamental harmonic measurements is examined in detail. As theoretical analyses are extremely complex due to a high nonlinearity and stochastic nature of the problem, simulation analysis is employed as the primary method for fast testing and confirmation of the paper hypothesis. The results of realistic simulations give the measurement uncertainties below 0,01 % and 0,013 %, for the measured grid voltage and current, respectively. Experimental validation has been carried out by comparison of the commercial instrument measurements and the measurements of SDMM based prototype instrument. It has been found that results are in accordance

Stochastic measurement of noise true RMS using two-bit flash A/D converters

U ovom radu je predstavljena primjena pristupa stohastičkog mjerenja u mjerenju efektivne vrijednosti i snage šuma. Struktura instrumenta je zasnovana na dva dvo-bitna flash analogno-digitalna (A/D) konvertora, na čije ulaze se dovodi diterovani šum, i na akumulaciji proizvoda konvertorskih izlaza. Izvedeni su novi teorijski izrazi za predviđanje rezultata mjerenja i mjerne nesigurnosti, koji uključuju stohastičku prirodu ulaznih signala. Ekstenzivne simulacije i eksperimenti dokazuju validnost predložene metode i njenu nisku mjernu nesigurnost, čak i pri relativno niskoj frekvenciji uzorkovanja. Ovo ukazuje da je prikazani instrument, osim za opću primjenu u mjerenju šuma, pogodan i za detekciju kemijskih i bioloških tvari, zasnovanu na upotrebi grafenskih senzora.The paper presents an application of the stochastic measurement approach for true RMS and power of noise. The instrument structure is based on two 2-bit flash analog-to-digital (A/D) converters whose inputs are the dithered noise, and on accumulation of the product of the converters’ outputs. New theoretical expressions for predicting measurement result and measurement uncertainty, with inclusion of input signal’s stochastic nature, are derived. Extensive simulations and experiments prove the validity of the proposed method and its low measurement uncertainty, even at a relatively low sampling rate. These indicate that, beside general applications for noise measurements, the instrument is suitable for chemical and biological substances detection that utilizes graphene sensors