Влияние погрешностей функции преобразования ацп на погрешность измерения среднего квадратического значения

Measuring a value by definition seems to be the best solution for getting the most precise results. In this paper, it is shown that by changing the general definition of root mean square (RMS) and average value of a periodic signal, their measurement can be improved. When measuring RMS with asynchronous sampling, it was observed that results were scattered around two values, and it was found that the main cause for this was initial sampling time. Redefining the RMS value has been proposed in order to increase the efficiency of the asynchronous method. After comparing the results based on general and proposed definition for RMS value, it was observed that there was significantly less scattering of results and higher accuracy. The simulation proved that the application of the proposed definition of RMS gives more accurate and precise results than the general definition for analog to digital (AD) converters with both lower and higher resolution.

Currently, digital methods are applied to measure the root mean square (RMS) of the signal in most cases. To obtain instantaneous values of the input signal in digital form, an analog-to-digital converter (ADC) is applied. Real ADCs have deviations (errors) of the conversion function from the linear one. These deviations can be presented as additive, multiplicative and nonlinear. Additive and multiplicative errors can be eliminated by zero adjustment and calibration of the measurement channel, respectively. To eliminate the nonlinearity of the ADC transfer function requires individual adjustment of the measurement channel of each device. This significantly increases the cost of the device. This article describes a technique ("combined" method of representation of the ADC nonlinearity), which allows to estimate of the RMS measurement error caused by the nonlinearity of the ADC transfer function. The analytical relations allowing to perform calculation of the error estimation are obtained. The proposed approach is compared with existing techniques. Simulation mathematical modeling is performed in Matlab and Simulink software packages. This allows to evaluate the correctness of the obtained analytical relations.

Implementation of photonic analog-to-digital convertor (ADC) using an optimal way of information parallelizing at the level of circuit solutions can significantly improve the performance of the total system (signal source - ADC - computing device). Traditional approach for fast photonic ADC uses processing every time-neighbor sample of input signal by its own channel. For the input signals with limited bandwidth, another approach can be used, in which every input signal spectral interval is processed by its own channel, and the width of the spectral interval is adjusted with the performance of an electronic ADC used for digitizing. In many cases, output signals of electronic ADCs are sufficient for obtaining necessary information from the input signal without joint processing of the output signals of all channels; otherwise, outputs of all channels can be Fourier-processed and concatenated to get complete spectrum of a wideband microwave input signal. For realization of this scheme, a mode locked stable laser together with an amplitude modulator and two combs of narrow band optical filters can be used. Alternatively, a mode locked laser can be replaced with a continuous wave (CW) laser together with a number of optical modulators. Performance capabilities for signal ADC using spectral intervals are estimated. Parameters for optimal system operation are derived. It is shown that, for modern optical elements, 8-10 effective bits can be achieved in the digitized signal.

The paper presents a method for increasing the resolution of parallel analog-to-digital converters (ADCs) with time compression of signals. It is established that analog-to-digital conversion of signals in parallel ADCs with time compression of output signals is performed in separate channels with non-identical bandwidths. Ultimately, this leads to a decrease in resolution when converting input signals. The difference in the bandwidths of parallel ADC channels is due to the features of the sample and store circuits (SSCs), which are installed at the inputs of each ADC. SSCs are necessary to reduce dynamic errors that arise when discretizing time-varying analog signals. The functioning of SSCs is based on the principle of fixing the instantaneous value of the input signal for the time required for further conversion in the ADC. The input circuits of SSCs can be represented as low-pass filters, in which there is a spread of the parameters of resistors and capacitors that determine the bandwidth of the i-th ADC channel. The passband adjustment in each ADC channel is carried out by switching resistors in the input circuits of the converter. To reduce the errors of non-identity of the passbands, it is proposed to introduce a reference additional ADC (АADC), which operates with a lower sampling frequency. In the operating mode, one of the ADC channels is calibrated. At the same time, the reference АADC operates with a sampling frequency that allows it to operate in phase with one of the working ADCs in each conversion cycle. A structural diagram of a parallel ADC (PADC) based on time compression of signals with correction of the passbands of individual ADC channels has been developed. The PADC operates in two modes: calibration and working with correction. In the calibration mode, a sinusoidal signal is supplied to the inputs of all PADC channels from the output of the test signal generator through an analog switch. The array of digital data from the output of the ADC is accumulated in a buffer storage device. Then, the accumulated array is fed to a computer via an interface adapter and a USB bus, where the errors of non-identity of the bandwidths of the ADC channels are calculated. Each ADC channel contains a digital-to-analog converter at the input, which performs the function of a digital potentiometer for the input signals of the SSC. The calculated transfer coefficients from the outputs of the control unit are fed to the corresponding ADC channels. Analysis of the ADC efficiency showed that by adjusting the bandwidths of individual channels of a 12-bit PADC, it is possible to improve the resolution in the low-frequency band by 0,5 bits, and in the high-frequency band by 1,9 bits.

Aim: This study sought to evaluate the effects of different irrigation solutions and sterilization processes on the surface properties of ProTaper Next (PTN; Dentsply-Maillefer, Ballaigues, Switzerland) and TruNatomy (TN; Dentsply Sirona, Ballaigues, Switzerland) nickel-titanium rotary files. Methodology: 30 ProTaper Next and 30 TruNatomy files were used. Both types of files were divided into five groups. The files in three groups were dipped into 5.25% NaOCI (CanalPro, Coltene/Whaledent, Altstätten, Switzerland), BioAKT (New Tech Solutions s.r.l., Brescia, Italy), and 18% etidronic acid (Dual Rinse HEDP, Medcem, Weinfelden, Switzerland), respectively, for 5 minutes, while the files in the fourth group were exposed to five autoclave cycles. The files in the fifth (control) group did not receive any treatment. Scans were performed from five different points using an atomic force microscope (AFM). The assumption of the conformity of the quantitative variables to a normal distribution was evaluated using the Kolmogorov-Smirnov test. A one-way analysis of variance was used to compare the quantitative measures between more than two independent groups, while the post-hoc least significant difference test was used for the pairwise comparisons (p˂0.05). Results: AFM images of the PTN and TN files in all the groups revealed surface irregularities. The root mean square (RMS) and depth values of the files dipped in NaOCI, BioAKT, and Etidronic acid were statistically higher than those of the control group (p<0.05). Moreover, the RMS and depth values were statistically higher in the files that had been subjected to five autoclave cycles when compared with the control group (p<0.05). The RMS values and depth values among the groups were found to be compatible. Conclusion: All the applications increased the surface roughness of the PTN and TN files. The Etidronic acid and sterilization applications were found to increase the RMS and depth values ​​the most when compared with the control group. How to cite this article: Öztekin F, Elmalı E. The effect of irrigation solutions and sterilization process on the surface properties of ProTaper Next and TruNatomy rotary files: An atomic force microscopy study. Int Dent Res 2022;12(2):39-46. https://doi.org/10.5577/intdentres.2022.vol12.no2.1 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Inhomogeneities in muscle activation reveal motor unit recruitment

By applying information theoretic concepts to analog-to-digital convertor (ADC) design, we have created a mathematical framework from which the fundamental limit for the resolution-bandwidth product of any ADC may be derived. We found the surprising result that the limiting resolution of any ADC is proportional to oversampling-ratio (OSR), as opposed to widely-held belief that the resolution is proportional to \(log_2(OSR)\), a dramatic increase in the achievable resolution. This result, which resembles Shannon’s well-known result for the capacity of a communication channel, represents a paradigm shift in our understanding of data conversion methods and provides encouragement that new methods may be found. Furthermore, to achieve this theoretical limit, the internal analog modulator (or filter) of an ADC should be a chaotic system, so that both small as well as large changes in the input signal cause large (but bounded) deterministic changes at the output of the modulator - analogous to the “Butterfly effect”. This led us to discover a new class of ADCs, which we call TurboADC’s, that can trade off resolution for bandwidth on the fly, keeping their product equal to the fundamental information theoretic limit. These designs impose modest requirements on the analog front-end resources and power at the expense of greater complexity in the back-end decoder. A discrete-time TurboADC proposed here is a hybrid of a 1st order Delta-Sigma modulator and a Cyclic ADC, with the best features of both designs - oversampling, noise shaping, and simplicity from the Sigma-delta ADC approach and fast half-interval searching from Cyclic ADC’s. Simulations of the proposed TurboADC confirm our finding that the resolution of an ADC may approach fundamental limit of OSR bits within the baseband.

We have designed single-bit comparators and multi-bit flash analog-to-digital converters (ADCs) using three flavors of periodic comparators; one flavor uses a differential “quasi-one-junction” SQUID (DQOS) comparator, the second use a differential SQUID wheel comparator (DSW) and the third uses a symmetric differential SQUID wheel comparator (SDSW) with time-interleaved clocks. We have also developed a new performance analysis scheme that enables full reconstruction of input signal using a single-bit comparator. The signal is reconstructed based on multiple beat frequency measurements that track the position of the comparator thresholds in response to a dc offset to the input signal. In addition, to eliminate the frequency dependent distortions resulting from impedance mismatches over wide bandwidths, the signal and clock distribution network have been optimized using EM simulations. For distributing the clock signal to the multi-bit comparators, a 50 Ω coplanar transmission line has been designed. Test results for a 1-bit DSW comparator demonstrates a performance of 4.5 bits of resolution in Gray code for a beat frequency test using a 20 GHz input signal and 5.3 bits for 10 GHz input. 4 and 8-bit versions of the flash ADC with a DQOS comparator and a 3-bit time-interleaved ADC using the SDSW comparator have also been designed. The DQOS ADC has been tested up to 25 GHz input signal frequency with performance of 4.3 bits of resolution in Gray code for 19.7 GHz input signal. The time-interleaved ADC performance is 4.3 bits for a 15 GHz beat frequency test with an effective sampling rate of 30 GHz.

This thesis deals with recurrent neural networks, a particular class of artificial neural networks which can learn a generative model of input sequences. The input is mapped, through a feedback loop and a non-linear activation function, into a hidden state, which is then projected into the output space, obtaining either a probability distribution or the new input for the next time-step. This work consists mainly of two parts: a theoretical study for helping the understanding of recurrent neural networks framework, which is not yet deeply investigated, and their application to non-linear prediction problems, since recurrent neural networks are really powerful models suitable for solving several practical tasks in different fields. For what concerns the theoretical part, we analyse the weaknesses of state-of-the-art models and tackle them in order to improve the performance of a recurrent neural network. Firstly, we contribute in the understanding of the dynamical properties of a recurrent neural network, highlighting the close relation between the definition of stable limit cycles and the echo state property of an echo state network. We provide sufficient conditions for the convergence of the hidden state to a trajectory, which is uniquely determined by the input signal, independently of the initial states. This may help extend the memory of the network and increase the design options for the network. Moreover, we develop a novel approach to address the main problem in training recurrent neural networks, the so-called vanishing gradient problem. Our new method allows us to train a very simple recurrent neural network, making the gradient not to vanish even after many time-steps. Exploiting the singular value decomposition of the vanishing factors in the gradient and random matrices theory, we find that the singular values have to be confined in a narrow interval and derive conditions about their root mean square value. Then, we also improve the efficiency of the training of a recurrent neural network, defining a new method for speeding up this process. Thanks to a least square regularization, we can initialize the parameters of the network, in order to set them closer to the minimum and running fewer epochs of classical training algorithms. Moreover, it is also possible to completely train the network with our initialization method, running more iterations of it without losing in performance with respect to classical training algorithms. Finally, it is also possible to use it as a real-time learning algorithm, adjusting the parameters to the new data through one iteration of our initialization. In the last part of this thesis, we apply recurrent neural networks to non-linear prediction problems. We consider prediction of numerical sequences, estimating the following input choosing it from a probability distribution. We study an automatic text generation problem, where we need to predict the following character in order to compose words and sentences, and a path prediction of walking mobile users in the central area of a city, as a sequence of crossroads. Then, we analyse the prediction of video frames, discovering a wide range of applications related to the prediction of movements. We study the collision problem of bouncing balls, taking into account only the sequence of video frames without any knowledge about the physical characteristics of the problem, and the distribution over days of mobile user in a city and in a whole region. Finally, we address the state-of-the-art problem of missing data imputation, analysing the incomplete spectrogram of audio signals. We restore audio signals with missing time-frequency data, demonstrating via numerical experiments that a performance improvement can be achieved involving recurrent neural networks.

The rapid development of digital technology requires higher Analog Digital Converter (ADC) sampling rates. Single-chip ADC is difficult to meet this require. The Time Interleaved ADC (TIADC) based on ADC parallel sampling can solve this problem and is therefore widely used. However, due to current hardware levels, the sampling interval of the TIADC is non-uniform and there is a time sampling error (TSE). There are currently a number of algorithms that can estimate the TSE, but must work in an environment where the frequency of the input signal is known. This paper improves an existing TSE estimation method that enables parameter estimation with unknown input signal frequencies. The proposed algorithm constructs the relationship between signal variance and TSE. In the implementation process, the TSE estimation value is inverted by statistical signal variance. Simulations show that the normalized TSE estimation error value variance is 0.01.

Synthetic instruments apply the flexibility and computational capabilities of a digital signal-processing platform to synthesize a wide variety of synthetic instruments. The emphasis presented in traditional descriptions of a synthetic instrument is the architecture and the capabilities of the digital signal processing (DSP) platform and the user interfaces to the same. In this paper we highlight and discuss considerations of the signal conditioning and signal collection tasks. The focal point of the signal collection process is the analog-to-digital converter (ADC), the element that defines the precision and the bandwidth of the sampled data representation of the signal processed by the DSP platform. Analog signal conditioning prior to the ADC performs the task of limiting the input signal bandwidth and possible translation of the spectral band center. Digital signal conditioning following the ADC continues to perform the same tasks by further limiting the bandwidth of the digitized input signal as well as performing spectral translation with appropriate sample rate changes. In addition, the post conversion process can correct gain, phase, and time delay imbalances between input signal paths as well as gain and phase distortion encountered in the analog signal path. We identify and address performance constraints of existing ADCs and present a number of signal processing-based options to enhance and extend the operating regimes of the analog signal conditioning and the ADC conversion process.

Several exercise methods, such as the Shaker exercise, tongue press exercise, chin tuck against resistance (CTAR) exercise, and submandibular push exercise, have been introduced to strengthen the muscles involved in swallowing. In this study, we compared the effectiveness of the CTAR, submandibular push, and Shaker exercises for the induction of selective supra- and infrahyoid muscle contractions using surface electromyography (EMG). This study is a prospective non-randomized controlled study. Twenty-five healthy subjects and 20 patients experiencing swallowing difficulty were enrolled. During the three different types of exercises, the root mean square (RMS) values of the sternocleidomastoid (SCM), suprahyoid (anterior belly of the digastric and mylohyoid muscles), and infrahyoid (sternothyroid and thyrohyoid muscles) muscles were analyzed using surface EMG. Differences in the activity of swallowing muscles among the three different exercises were analyzed using one-way repeated measured analysis of variance. In terms of both the maximum and mean RMS values of the suprahyoid muscle, the submandibular push exercise showed a larger RMS value than the CTAR and Shaker exercises in healthy subjects (p < 0.05). In terms of both the maximum and mean RMS values of the suprahyoid muscle, the Shaker exercise and submandibular push exercise showed a larger RMS value than the CTAR exercise in patients with swallowing difficulty (p < 0.05). The submandibular push exercise may be effective as a swallowing muscle exercise owing to its superiority in inducing selective contractions of the supra- and infrahyoid muscles. The CTAR and Shaker exercises are also effective in this regard.

In recent years, real-time global ionospheric map (RT-GIM) products have been actively developed by the international global navigation satellite system (GNSS) service (IGS) and its ionosphere associate analysis centers (IAACs) along with the increase of RT-GNSS multi-frequency and multi-constellation observations. In this study, the accuracy and consistency of three RT-GIM products from the Chinese Academy of Sciences (CAS), Wuhan University (WHU), and IGS are evaluated and analyzed utilizing three validation methods, namely, comparison with JASON-3 vertical total electron content (VTEC), the difference of slant total electron content (dSTEC), and IGS combined final GIM (IGSG) data. The test period was from 1 January 2019 to 31 December 2022, including the different solar activities. First, the comparison with JASON-3 data illustrates that the quality of the three RT-GIM products over oceans is in great consistency with that of the IGSG during different levels of solar activity and the daily mean bias (MEAN) values in low and high solar activities are approximately 5 and 10 TECU, respectively. The root mean square (RMS) values under low and high solar activities can be up to 7 and 12 TECU. Furthermore, the dSTEC validation results present that the MEAN values of RT-GIM products from different IAACs at high- and mid-latitude stations are about 0.5 TECU, which is smaller than those at low-latitude stations at about 1 TECU over continental regions. The standard deviation (STD) and RMS values for various RT-GIM products are within 3 and 4 TECU at low latitudes, respectively. In terms of the comparison with IGSG, the result shows that IGS combined RT-GIM (IRTG) presents better consistency than CAS RT-GIM (CRTG) and WHU RT-GIM (WRTG) in 2021 and 2022, with average annual STD and RMS values of 2.56 and 2.78 TECU, respectively. The daily biases of the RT-GIM products relative to IGSG can reach 4 TECU in high solar activities and the daily STD and RMS values are mainly within the 5 to 6 TECU range, respectively.

ObjectivesTo evaluate the effect of additive and subtractive manufacturing on the accuracy (trueness and precision) of fixed partial denture patterns (FPDPs) used for casting or pressing. Materials and MethodsA 3-unit complete coverage FPD on mandibular right first premolar and first molar teeth was virtually designed. Using the design data, FPD patterns were fabricated from an additively manufactured resin (PR, ProArt Print Wax) and 2 CAD-CAM wax discs (YW, ProArt CAD Wax Yellow and BW, ProArt CAD Wax Blue) (n = 10). Each pattern was then digitized with a scanner (CEREC Primescan) and evaluated for 3D surface deviation at 4 different surfaces (overall, external, marginal, and intaglio surfaces) by using a 3D analysis software (Medit Link). Root mean square (RMS) values were automatically calculated. Data were analyzed by using Kruskal-Wallis and Dunn's post hoc tests for trueness and precision (α= 0.05). ResultsSignificant differences were found among the RMS values for overall (P<.001) and each surface (P≤.040) evaluated. PR had the highest overall (P≤.011) and intaglio surface (P≤.01) deviations, while the difference between YW and BW was not significant (P≥.199). PR had the highest (P≤.027) and BW had the lowest (P≤.042) external surface mean RMS values. BW had higher mean marginal RMS value than YW (P=.047). For precision, significant differences were observed among test groups only for marginal RMS values (P=.002). PR had lower precision than BW (P=.002). ConclusionsBW and YW FPDPs mostly had higher trueness compared with PR FPDPs. However, considering relatively smaller deviations at marginal and intaglio surfaces and the fact that patterns mostly had similar precision, clinical fit of FPDs fabricated by using tested patterns may be similar. Clinical SignificanceDefinitive 3-unit fixed partial dentures fabricated by using tested patterns may be similar. However, FPDs fabricated with tested additively manufactured resin patterns might result in more chairside adjustments than those fabricated with tested subtractively manufactured wax patterns.

To investigate the influence of different gingival colors and finish line locations on the accuracy of intraoral scans for complete-arch tooth preparation. Ten complete-arch maxillary models with 5 different gingival colors [light pink (LP), dark pink (DP), orange (Or), brown (Br), and purple (P)] and 2 different finish line locations [equigingival (Eq) and subgingival (Sb)] were used. Ten scans of each reference model were made with an intraoral scanner and exported as STL files. Assessment of precision and trueness was conducted with 3D analysis software. Each STL file was individually aligned with the reference scan and 3D differences were calculated using the root mean square (RMS) value. Data were statistically analyzed using 2-way ANOVA and Tukey HSD tests (α=.05). Regarding trueness, significant differences were found between different gingival colors and finish line locations. The highest mean RMS value was found in the gingival color group of Or with Sb finish line. Regardless of the finish line location applied, significantly lower RMS values were found in the gingival color groups of Br and P. Regarding precision, finish line location significantly influenced the mean RMS values of LP, DP, and Or. Regardless of the finish line location applied, significantly lower RMS values were obtained in the gingival color groups of Br and P. Gingival color influenced the scan accuracy of complete-arch tooth preparation. When the gingival color was a darker gingival color, the scan accuracy was improved, especially in the case of a subgingival finish line location.