Digital Error Research Articles

On electromagnetic head digitization in MEG and EEG

In MEG and EEG studies, the accuracy of the head digitization impacts the co-registration between functional and structural data. The co-registration is one of the major factors that affect the spatial accuracy in MEG/EEG source imaging. Precisely digitized head-surface (scalp) points do not only improve the co-registration but can also deform a template MRI. Such an individualized-template MRI can be used for conductivity modeling in MEG/EEG source imaging if the individual’s structural MRI is unavailable. Electromagnetic tracking (EMT) systems (particularly Fastrak, Polhemus Inc., Colchester, VT, USA) have been the most common solution for digitization in MEG and EEG. However, they may occasionally suffer from ambient electromagnetic interference which makes it challenging to achieve (sub-)millimeter digitization accuracy. The current study—(i) evaluated the performance of the Fastrak EMT system under different conditions in MEG/EEG digitization, and (ii) explores the usability of two alternative EMT systems (Aurora, NDI, Waterloo, ON, Canada; Fastrak with a short-range transmitter) for digitization. Tracking fluctuation, digitization accuracy, and robustness of the systems were evaluated in several test cases using test frames and human head models. The performance of the two alternative systems was compared against the Fastrak system. The results showed that the Fastrak system is accurate and robust for MEG/EEG digitization if the recommended operating conditions are met. The Fastrak with the short-range transmitter shows comparatively higher digitization error if digitization is not carried out very close to the transmitter. The study also evinces that the Aurora system can be used for MEG/EEG digitization within a constrained range; however, some modifications would be required to make the system a practical and easy-to-use digitizer. Its real-time error estimation feature can potentially improve digitization accuracy.

Digital pathology implementation in a private laboratory: The CEDAP experience

IntroductionThe transition to digital pathology has been carried out by several laboratories across the globe, with some cases described in Portugal. In this article, we describe the transition to digital pathology in a high-volume private laboratory, considering the main challenges and opportunities. Material and methodsOur process started in 2020, with laboratory workflow adaptation and we are currently using a high-capacity scanner (Aperio GT450DX) to digitize slides at 20×. The visualization system, Aperio eSlide Manager WebViewer, is integrated into the Laboratory System. The validation process followed the Royal College of Pathologists Guidelines. ResultsRegarding validation, the first phase detected an error rate of 6.8%, mostly due to digitization errors. Phase optimization and collaboration with technical services led to improvements in this process. In the second validation phase, most of the slides had the desired quality for evaluation, with only an error rate of 0.6%, corrected with a new scan. The interpathologist correlation had a total agreement rate of 96.87% and 3.13% partial agreement. ConclusionThe implementation and validation of digital pathology was a success, being ready for prime time. The total integration of all laboratory systems and the acquisition of new equipment will maximize their use, especially with the application of artificial intelligence algorithms.

A Low-Cost Digital Twin-Driven Positioning Error Compensation Method for Industrial Robotic Arm

In robotic arms, transmission error will cause positioning error, which increases with the wear and tear of the transmission mechanism. Positioning error will degrade the performance of the robotic arm. It is necessary to carry out intelligent maintenance for the robotic arm. In this article, a low-cost digital twin (DT)-driven positioning error compensation method is proposed for robotic arm. The DT model of the robotic arm is first established, including the physical layer, data transfer layer, model layer, functional layer, and application service layer. A low-cost attitude sensor is then applied to provide actual information of the robotic arm to the DT model. When the DT model senses the positioning error of the robotic arm, it reduces the positioning error by adjusting the motor angle. The effectiveness of the proposed method is finally verified by the experimental results under different conditions.

Error Analysis of Digital Electric Energy Metering Based on FPGA

With the emergence and development of smart grid, digital meters have been widely used in substations, so the research on digital energy metering error has become a research hotspot. The purpose of this paper is to analyze the error of digital power measurement based on FPGA, mainly take the analog input fusion module and digital power meter in the digital power measurement system as the research object, and analyze the source of measurement error. An FPGA-based energy metering error detection platform is built to analyze the energy metering error when there are harmonics in the full energy metering method currently used by most digital energy meter manufacturers. The comparative analysis of numerical integration algorithms shows that the asymmetric distortion rates of the simulated waveforms are approximate. The results of measurement error analysis under harmonic conditions show that when the number of sampling points per cycle is 60, the power measurement errors of the 2nd to 4th harmonics are equivalent. The magnitude of the measurement error is still consistent with other low-order harmonics, and the simulation results are consistent with the theoretical analysis results.

Whole-process visualization and in-situ monitoring of tunable diode laser absorption spectroscopy for optical gas sensing

Optical gas sensing based on tunable diode laser absorption spectroscopy (TDLAS) has characteristics of high sensitivity and real-time response, but interferences and distortions may result in fluctuations and errors in the precious and stable measurement of gas concentration. Therefore, it is required to monitor and analyze parameters and waveforms throughout the TDLAS process. We propose and establish a visualized architecture with real-time interfaces and modules for the complete TDLAS process. It basically includes several functional modules, i.e., multiple frequency laser driving, operating temperature control, harmonic processing, and curve fitting, allowing elaborately in-situ monitoring the overall working status. The digital error amplifier based on type II compensation network for the proportional-integral-differential feedback controller was developed. Generated first and second harmonics and dual channel digital phase-locking algorithms were also developed in the TDLAS system. In the gas sensing experiment, the driving signal of the laser includes a 5-Hz triangular wave and a 1-kHz sine wave, and results show the favorable laser operating temperature variation of below ±0.02 ° C and the concentration calibration. The overall estimated measurement errors in the experiment are about 4.55% for the 300-ppmv gas. This visualization and in-situ monitoring system are helpful and universal for the optimization, calibration, and improvement of the TDLAS-related optical gas sensing.

P037: High breadth whole exome sequencing of circulating tumor DNA identifies novel recurrent genetic alterations in Hodgkin lymphoma

Hodgkin lymphoma (HL) is a B-cell lymphoma with a generally favorable prognosis. However, side effects of aggressive front-line treatment and difficult-to-treat relapsed/refractory disease are still a clinical challenge. A better understanding of the biological diversity of HL at baseline might help to further individualize the treatment of patients and thus ultimately improve outcome. A broad characterization of the genetic drivers of HL is highly important to improve our understanding of the biological diversity of HL. Here, we present the results of our study using whole-exome sequencing of circulating tumor (ct)DNA to broadly characterize the HL oncogenome in 165 patients. After extraction of germline and cell-free DNA, WES was performed, targeting 37 Mb of the human genome. An in-house customized bioinformatic pipeline including twofold error reduction using unique molecular identifiers (UMIs) and digital error suppression was used as previously described by us (Sobesky et. al., Med, 2021). The median ctDNA concentration per patient was 2.26 log haploid genome equivalents per milliliter (log hGE/ml) (range: 1.41–4.18 log hGE/ml) without significant correlation with clinical parameters such as sex, international prognostic score (IPS) or clinical stage. In addition to the detection of several genetic aberrations involved in the pathogenesis of HL (such as B2M, CSF2RB, GNA13, SOCS1), we were able to detect several novel, recurrently mutated potential oncogenes and tumor suppressor genes. Among the most frequently mutated genes not previously described in HL were olfactory receptor family 10 subfamily G member 7 (OR10G7) (11.5%), Apolipoprotein B (APOB) (10.3%) and Filaggrin 2 (FLG2) (9.7%). Furthermore, several previously undescribed copy number variations (CNV) were detected (losses: 13q13.1, 1p36.13a, 6p21.33; gains: 19q13.42, 9p24, 12q12). To decipher the detected genes’ and CNVs’ contribution to the biological diversity of HL, we performed non-negative matrix factorization. Furthermore, neoantigen load was assessed through human-leukocyte antigen (HLA) sequencing. Detailed results will be presented at the meeting. In conclusion, our ctDNA based WES approach provides sufficient sensitivity to both perform genotyping in HL and detecting novel genomic aberrations potentially involved in the pathogenesis of HL.

Parallel Analysis of Pre- and Postoperative Circulating Tumor DNA and Matched Tumor Tissues in Resectable Pancreatic Ductal Adenocarcinoma: A Prospective Cohort Study.

Circulating tumor DNA (ctDNA) is a promising biomarker for early tumor detection and minimal residual disease (MRD) assessment in early-stage cancer, but quantifying minute amounts of ctDNA is challenging and well-designed studies on ctDNA in early-stage cancer are still lacking. Here, we adapted a sensitive next-generation sequencing (NGS) technology and performed parallel analysis of pre- and postoperative ctDNA and matched tumor tissues in a prospective cohort of patients with resectable pancreatic ductal adenocarcinoma (PDAC). In total, 70 consecutive patients undergoing curative resection for resectable PDAC were enrolled. We performed integrated digital error suppression-enhanced cancer personalized profiling by deep sequencing NGS of triple-matched samples (pre/postoperative plasma cell-free DNA [cfDNA], tumor tissue, and genomic DNA) targeting 77 genes. Preoperative ctDNA was detected in 37.7% of the evaluable patients, with a median variant allele frequency of 0.09%. Twelve additional oncogenic mutations were detected exclusively in preoperative ctDNA but not in tissue. When quantitative concentrations of ctDNA were estimated in haploid genome equivalents per milliliter (hGE/mL), the risk of early recurrence was high in patients with postoperative ctDNA >1 hGE/mL. cfDNA variants from 24.5% of patients had features compatible with clonal hematopoiesis. An optimized NGS approach might add value beyond tissue analysis through the highly sensitive detection of minute amounts of ctDNA in resectable PDAC. Postoperative ctDNA concentration could be a tool for MRD assessment. Moreover, parallel analyses of matched tissues and leukocytes might be required to accurately detect clinically relevant ctDNA.

A coherent-averaged dual-comb spectrometer based on environment-shared fiber lasers and digital error correction

Dual-comb spectroscopy (DCS) has been an emerging spectrometric technique with high resolution, high sensitivity, broad spectral range and fast acquisition speed. However, it is hard to achieve high long-term stability and high mutual coherence with low system complexity, which hinders the widespread usage in field-deployed applications. In this paper, we demonstrate a simplified free-running dual-comb spectrometer with long-term stability and mode-resolved resolution. Two free-running mode-locked fiber lasers are environment-shared to achieve effective common-mode noise suppression, which enables long-term aliasing-free dual-comb interferograms (IGMs). Post-proposing error correction algorithm is then utilized to recover full mutual coherence and realize coherent averaging. As a result, the transmittance spectra of H13CN and C2H2 gases with high resolution and high signal-to-noise ratio (SNR) can be measured. To the best knowledge of us, this is the first demonstration of coherent-averaged DCS based on environment-shared free-running fiber lasers, which is promising for promoting the dual-comb spectrometer out of the laboratory and realizing field-deployed applications.

An Inverter-Nonlinearity-Immune Offline Inductance Identification Method for PMSM Drives Based on Equivalent Impedance Model

In the existing offline inductance identification methods of permanent magnet synchronous machines (PMSMs), <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis voltage equations are generally adopted and the inverter nonlinearity compensation is necessary, which complicates the identification process and restricts the generality. In order to solve the problem, an offline inverter-nonlinearity-immune inductance identification method is proposed in this article based on the PMSM equivalent impedance model. The method can identify the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis inductances by injecting both dc and high frequency signals, where the magnetic saturation and the cross saturation are considered. Besides, an inductance surface forming algorithm is introduced based on the bilinear interpolation. The continuous <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis inductance surfaces can be then obtained by only a few identified data, so that the time of data sampling and processing is greatly shorten compared with the existing methods. To enhance the accuracy of the identification method, the digital delay error and the sampling error in zero current zone are investigated and compensated. The effectiveness of the proposed method is validated on three different test machines.

A Fractional-N Digitally Intensive PLL Achieving 428-fs Jitter and &lt;−54-dBc Spurs Under 50-mVpp Supply Ripple

In this article, we present a 4.5–5.1-GHz fractional- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> digitally intensive phase-locked loop (DPLL) capable of maintaining its performance in face of a large supply ripple, thus enabling a direct connection to a switched-mode dc–dc converter. Supply pushing of its inductor–capacitor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$LC$ </tex-math></inline-formula> ) oscillator is suppressed by properly replicating the supply ripple onto the gate of its tail current transistor, while the optimum replication gain is determined by a new on- chip calibration loop tolerant of supply variations. A proposed configuration of cascading a supply-insensitive slope generator with an output of a current digital-to-analog converter (DAC) linearly converts the phase error timing into a corresponding voltage, which is then quantized by a successive approximation register (SAR) analog-to-digital converter (ADC) to generate a digital phase error. We also introduce a low-power ripple pattern estimation and cancellation algorithm to remove the phase error component due to the supply-induced delay variations of loop components. Implemented in 40-nm CMOS, the DPLL prototype achieves the performance of 428-fs rms jitter, <−55-dBc fractional spur, and <−54-dBc maximum spur while consuming 3.25 mW and being subjugated to a sinusoidal or sawtooth supply ripple of 50 mV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> at 50-MHz reference divided by 3, 6, or 12.

Investigation of image plane for image reconstruction of objects through diffusers via deep learning.

.Significance: The imaging of objects hidden in light-scattering media is a vital practical task in a wide range of applications, including biological imaging. Deep-learning-based methods have been used to reconstruct images behind scattering media under complex scattering conditions, but improvements in the quality of the reconstructed images are required.Aim: To investigate the effect of image plane on the accuracy of reconstructed images.Approach: Light reflected from an object passing through glass diffusers is captured by changing the image plane of an optical imaging system. Images are reconstructed by deep learning, and evaluated in terms of structural similarity index measure, classification accuracy of digital images, and training and testing error curves.Results: The reconstruction accuracy was improved for the case in which the diffuser was imaged, compared to the case where the object was imaged. The training and testing error curves show that the loss converged to lower values in fewer epochs when the diffuser was imaged.Conclusions: The proposed approach demonstrates an improvement in the accuracy of the reconstruction of objects hidden through glass diffusers by imaging glass diffuser surfaces, and can be applied to objects at unknown locations in a scattering medium.

Modeling of the Quantization Effects on the Resolution Uncertainty of Digital Indicators

In this research article, the effects of digital indicator resolution quantization error on uncertainty were analyzed. A proposed new simple mathematical model was developed to identify and evaluate the quantization effects of digital display instruments. Based on this developed model, the quantization effects are greatly affected by the index of the indication N-bit wordlengths that intern affects the quantization error. However, the modified resolution uncertainty is slightly affected by the upper bounds of the visible zone of the digital indicator. This proposed algorithm is an important milestone for the metrologists to evaluate the effects of quantization error of the displayed and measured values, especially at high-precision measurements, as in international comparisons.

A Method for Determining the Shape Similarity of Complex Three-Dimensional Structures to Aid Decay Restoration and Digitization Error Correction

This paper introduces a new method for determining the shape similarity of complex three-dimensional (3D) mesh structures based on extracting a vector of important vertices, ordered according to a matrix of their most important geometrical and topological features. The correlation of ordered matrix vectors is combined with perceptual definition of salient regions in order to aid detection, distinguishing, measurement and restoration of real degradation and digitization errors. The case study is the digital 3D structure of the Camino Degli Angeli, in the Urbino’s Ducal Palace, acquired by the structure from motion (SfM) technique. In order to obtain an accurate, featured representation of the matching shape, the strong mesh processing computations are performed over the mesh surface while preserving real shape and geometric structure. In addition to perceptually based feature ranking, the new theoretical approach for ranking the evaluation criteria by employing neural networks (NNs) has been proposed to reduce the probability of deleting shape points, subject to optimization. Numerical analysis and simulations in combination with the developed virtual reality (VR) application serve as an assurance to restoration specialists providing visual and feature-based comparison of damaged parts with correct similar examples. The procedure also distinguishes mesh irregularities resulting from the photogrammetry process.

Research on the Method of Prediction for Fuzzy Tooth Surface of Involute Gear

Surface appearance of involute gear is the basis to research the dynamic performance of gear transmission system. The Delaunay triangulation method of layered local dynamic is proposed to construct the precise tooth surface of the known tooth surface appearances. The concave and convex region of the real tooth surface was extracted by isosurface subdivision. In order to smooth the surface, the energy method and the improved fractal method with minimum included angle are used to smooth the curve. On the basis of the loaded tooth contact analysis of involute gears, the loaded tooth contact analysis model of digital error tooth surface is constructed. The tooth surface appearances of fuzzy tooth surface were predicted by extracting contact patterns under various working parameters on the experimental platform. Through the analysis on actual examples, it is concluded that the method proposed in this manuscript can accurately predict the tooth surface morphology of fuzzy tooth surface and lay the foundation for the dynamic performance optimization of gear system with fuzzy tooth surface.

An improved temporal phase unwrapping based on super-grayscale multi-frequency grating projection

Multi-frequency temporal phase unwrapping (TPU) is an essential algorithm in phase-shifting profilometry, especially when measuring surface discontinuities and isolated objects. The unit-frequency phase with primary contour information guides the high-frequency wrapped phase with measured objects' detail information unwrapping. Ordinary, the projected digital grating is of 256-grayscale at most for the 256-grayscale standard of the projector. The digital error will inevitably be introduced into the projection grating, leading to the phase error in each wrapped phase calculation. Using unit-frequency phase with error will directly affect the low-frequency and high-frequency wrapped phases unwrapping, thus limiting the phase unwrapping accuracy to some extent. In this work, by skillfully using the time-division multiplexing characteristic of projector and the integral characteristic of CCD camera, a high accuracy temporal phase unwrapping method based on super-grayscale multi-frequency grating projection is proposed. The expected super-grayscale rather than traditional 256-grayscale multi-frequency gratings are purposefully designed to reduce the digital error initially. The captured realistic super-grayscale patterns can calculate the high-resolution phase information, so that the reliable unit-frequency phase can guide the low-frequency and high-frequency fringe order calculation more precisely, and improve the measurement accuracy initially. The experimental results verify the validity and practicability of the proposed method.

Fault-tolerant control via four-leg inverter of a full-electric propulsion system for lightweight fixed-wing UAVs

The work deals with the development and the performance characterization of a novel control strategy for the detection, isolation and accommodation of coil faults in a three-phase Permanent Magnet Synchronous Motor (PMSM), used to drive the propeller of a modern lightweight fixed-wing UAV. The health-monitoring algorithms on motor currents (used to detect the open-circuit fault and to activate the control reconfiguration) are based on a slope method, associated to the evaluation of the current phasor trajectory in the Clarke plane. Actually, when an open-circuit fault occurs in PMSM driven by a standard three-leg converter, the typical circular trajectory of the current phasor in the Clarke plane collapses into a linear track and relevant torque ripples are generated. On the other hand, if the PMSM is driven by a four-leg converter, a control reconfiguration can be applied: the fourth leg of the power bridge is in stand-by when the system operates without faults, but it is enabled to regulate the current flowing at the central point of the Y connection of the 3-phase PMSM. The performances of the fault-tolerant algorithms are assessed via detailed nonlinear simulation of the propulsion system (including propeller loads, electrical faults, mechanical transmission compliance, digital signal processing and sensors errors). The results demonstrate that the health-monitoring algorithms and the fault-tolerant control strategies permit to obtain extremely small detection and isolation latencies, and negligible performance degradation in terms PMSM torque.

A 12.5-GHz Fractional-N Type-I Sampling PLL Achieving 58-fs Integrated Jitter

This article presents a fractional-N sampling type-I phase-locked loop (PLL). To overcome the impairments of a conventional type-I PLL, namely the frequency-tuning-dependent time offset and the narrow range of the sampling phase detector (SPD), which would prevent fractional-N synthesis, a novel digital phase error correction (DPEC) technique, operating in the background, is introduced, which provides robust low-jitter performance. Besides, a novel frequency locking method is presented, which provides fast lock and seamless hand-off to main PLL operation. The PLL has been fabricated in a 28-nm CMOS technology process, and it synthesizes frequencies from 11.9 to 14.1 GHz, achieving an rms jitter of 58.2 and 51.7 fs (integrated into the 1 kHz-100 MHz bandwidth) for a fractional-N and integer-N channel, respectively. The reference spur is as low as -73.5 dBc, while the worst case near-integer fractional spurs are lower than -63.2 dBc. With a power consumption of 18 mW, the jitter-power figure of merit is -252.1 dB (fractional-N) and -253.3 dB (integer-N). The locking time is below 9 μs for a 1-GHz frequency step. The synthesizer occupies 0.16 mm², including decoupling capacitors.

Visual Trends of the 21st Century in Graphic Design: Interpretation of Virtual Space Attributes

The article presents an attempt to characterize the graphic design transformation under the impact of virtual space with its unified elements. It has been established that the change of the graphic designer’s role in the system of modern information technologies development has caused the professional responsibility expansion at the intersection of real and virtual environments. The article aims to investigate the use of virtual space attributes (Internet page and mobile device interface elements) in uncharacteristic printed forms (for example, poster and packaging design) as a modern approach to graphic design that expands the designer’s visual language. The virtual environment elements, reproduced by graphic designers, are described, and their applications in print and “native” environments are compared. The groups selected for borrowing are as follows: system navigation elements, alert dialogs, menu bars, search bars, tags, and particular process progress indicator. The article highlights the imitation of raster in graphic design objects as digital images loading errors. It has been found that, first, the elements retain their recognizability and original meanings even beyond the context. Secondly, although virtual systems are structured, eliminating the number of unnecessary actions of the user, and possible errors, the incorrect program operation, in the form of alert windows, is the most attractive for copying. Third, borrowed elements are self-sufficient and their value approaches to the sign. The data of the article are of practical importance for graphic designers at the stage of project concept development.

A Reference Clock Doubler with Fully Digital Duty-cycle Error Correction Controller

In this paper, a clock frequency doubler capable of handling large variation in input duty cycle and PVT (Process, Voltage and Temperature) is presented. Clock doubler with XOR gate cannot be used if the duty of the input clock is not 50 %. A circuit that calibrates the duty to 50 % is added in front of the clock doubler, the clock doubler has a low jitter and doubles the frequency even if the duty of the input clock is not 50 %. The fully digital method proposed in this paper overcomes the disadvantages of the existing analog methods, such as standby current and large area due to the use of capacitors and amplifiers, to enable low-current, low-area implementation. The reference clock doubler is implemented using 55-nm CMOS process and the die area is 80 μm x 80 μm. The power consumption is 30 μW under the supply voltage of 1 V. Measured maximum duty cycle error correction range and average frequency error are ±30 % and less than 0.5 %, respectively.

BatchBMD as an Efficient and Accurate Dual-Energy X-ray Absorptiometry Report Generator.

Dual-energy X-ray absorptiometry is the gold standard for evaluating Bone Mineral Density (BMD); however, a typical BMD report is generated in a time-inefficient manner and is prone to error. We developed a rule-based automated reporting system, BatchBMD, that accelerates DXA reporting while improving its accuracy over current systems. BatchBMD generates a structured report, customized to the specific clinical purpose. To compare BatchBMD to a Web-based Reporting (WBR) system for efficiency and accuracy, 500 examinations were randomly chosen from those performed at the Taipei Municipal Wanfang Hospital from January to March 2021. The final assessment included all 2326 examinations conducted from September 2020 to March 2021. The average reporting times were 6.7 and 10.8 min for BatchBMD and the WBR system, respectively, while accuracy was 99.4% and 98.2%, respectively. Most of the errors made by BatchBMD were digit errors in the appendicular skeletal muscle index. After correcting this, 100% accuracy across all 2326 examinations was validated. This automated and accurate BMD reporting system significantly reduces report production workload for radiologists and technicians while increasing productivity and quality. Additionally, the portable software, which employs a simple framework, can reduce deployment costs in clinical practice.