Digital Error Research Articles

Quantitative evaluation of common errors in digital impression obtained by using an LED blue light in-office CAD/CAM system.

This study addresses common errors that may occur during digital impression procedures using the CEREC AC and in-office CAD/CAM systems. Error types and frequencies resulting from digital impressions of the oral cavity were investigated and their origins identified to facilitate the acquisition of more accurate digital impressions. A total of 1,251 digital impression cases, including 163 onlays and 1,088 inlays, were constructed as restorations using the CEREC AC system. Two evaluators determined five categories of digital errors as a basis for evaluation over two sessions. The five categories were as follows: inappropriate scanner positioning (ISP), improper handling of the scanner (IHS), irregular powder arrangement (IPA), improper cavity preparation (ICP), and insufficient scanned data (ISD). The most frequently encountered errors were non-linear powder application (IPA), inappropriate oral cavity scanner placement (ISP), and insufficient data (ISD). ISP showed that inlays had a slightly higher frequency of errors, but this observation was not statistically significant (P > .05). Most errors are caused by incorrect operation of intraoral scanners or uneven application of powder in acquiring digital impressions. To provide optimal digital impression results, careful chairside technique procedures and operation of intraoral scanners are required.

Demonstration of a quantum error detection code using a square lattice of four superconducting qubits.

The ability to detect and deal with errors when manipulating quantum systems is a fundamental requirement for fault-tolerant quantum computing. Unlike classical bits that are subject to only digital bit-flip errors, quantum bits are susceptible to a much larger spectrum of errors, for which any complete quantum error-correcting code must account. Whilst classical bit-flip detection can be realized via a linear array of qubits, a general fault-tolerant quantum error-correcting code requires extending into a higher-dimensional lattice. Here we present a quantum error detection protocol on a two-by-two planar lattice of superconducting qubits. The protocol detects an arbitrary quantum error on an encoded two-qubit entangled state via quantum non-demolition parity measurements on another pair of error syndrome qubits. This result represents a building block towards larger lattices amenable to fault-tolerant quantum error correction architectures such as the surface code.

Learning discriminant DCT coefficients driven block descriptor for digital dropout detection system in degraded archived media

Digitization of old archived media is of great importance to preserve the originality of medium in terms of historical record as well as the means to quality improvement for reproduction purposes. However, digitization increases the exposure of the media to digital dropout error, thus presenting a significant degradation in perceptual quality of the converted video sequences. A numbers of mechanisms were investigated in the past to make these converted media more robust against digital dropout errors. Nevertheless, these techniques achieved little success, forcing manual quality check to assure standard quality. This paper presents an automatic solution to this problem based on discriminant DCT coefficients. Here, the idea is to build a block classification model by learning discriminant DCT coefficients first and utilize these coefficients along with an weighted neighborhood sampling strategy to formulate discriminant block descriptor so that within-class difference of the block features is minimized and between-class difference is maximized. This spatial detection is free from motion computation; thus performs accurately in presence of pathological motion (PM) and fast moving objects. Finally, the proposed method is compared against the existing methods to demonstrate improved detection accuracy using real degraded video archives.

Digital Error Correction for a 10-Bit Straightforward SAR ADC

This paper proposes a 10-b SAR ADC. To increase the conversion speed and reduce the power consumption and area, redundant cycles were implemented digitally in a capacitor DAC. The capacitor DAC algorithm was straightforward switching, which included digital error correction steps. A prototype ADC was implemented in CMOS 0.18-μm technology. This structure consumed 140μW and achieved 59.4-dB SNDR at 1.25MS/s under a 1.8-V supply. The figure of merit (FOM) was 140fJ/conversion-step.

A Decision-Error-Tolerant 45 nm CMOS 7b 1 GS/s Nonbinary 2b/Cycle SAR ADC

A compact decision-error-tolerant 2b/cycle SAR ADC architecture is presented. Two DACs with different designated functions, SIG-DAC and REF-DAC, are implemented to make the structure compact and to eliminate the sampling skew issue. Use of a nonbinary decision scheme with decision redundancies not only increases the ADC speed with a relaxed DAC settling requirement but also makes the performance robust to reference fluctuations and comparator offset variations. The proposed dynamic register and direct DAC control scheme enhance the conversion speed by minimizing logic delay in the SAR decision loop. The proposed comparator-error detection with digital error correction scheme enhances high-speed ADC performance. A prototype 7b ADC fabricated in a 45 nm CMOS process operates at a sampling rate of 1 GS/s under a 1.25 V supply while achieving a peak SNDR of 41.6 dB and maintaining an ENOB higher than 6 up to 1.3 GHz signal frequency. The FoM under a 1.25 V supply is an 80 fJ/conversion-step with a power consumption of 7.2 mW.

Strong experimental guarantees in ultrafast quantum random number generation

We describe a methodology and standard of proof for experimental claims of quantum random-number generation (QRNG), analogous to well-established methods from precision measurement. For appropriately constructed physical implementations, lower bounds on the quantum contribution to the average min-entropy can be derived from measurements on the QRNG output. Given these bounds, randomness extractors allow generation of nearly perfect ``$\ensuremath{\epsilon}$-random'' bit streams. An analysis of experimental uncertainties then gives experimentally derived confidence levels on the $\ensuremath{\epsilon}$ randomness of these sequences. We demonstrate the methodology by application to phase-diffusion QRNG, driven by spontaneous emission as a trusted randomness source. All other factors, including classical phase noise, amplitude fluctuations, digitization errors, and correlations due to finite detection bandwidth, are treated with paranoid caution, i.e., assuming the worst possible behaviors consistent with observations. A data-constrained numerical optimization of the distribution of untrusted parameters is used to lower bound the average min-entropy. Under this paranoid analysis, the QRNG remains efficient, generating at least 2.3 quantum random bits per symbol with 8-bit digitization and at least 0.83 quantum random bits per symbol with binary digitization at a confidence level of 0.999 93. The result demonstrates ultrafast QRNG with strong experimental guarantees.

Challenges and Opportunities for Digital History

Challenges and Opportunities for Digital History

Assessment of Scoliotic Deformity Using Spinous Processes: Comparison of Different Analysis Methods of an Ultrasonographic System

ObjectiveThe purpose of this study was to evaluate the performance of 5 analysis methods in quantifying scoliotic deformity, using the spatial positions of SP tips acquired by a custom-developed ultrasound-based system, with different curve fitting methods and angle metrics in terms of their correlation with Cobb angle, test-retest reliability, vulnerability to digitization errors, and accuracy of identifying end vertebrae and convexity direction. MethodsThree spinal column dry bone specimens were randomly configured to 30 different scoliotic deformities. Raw spatial data of the SP tips were processed by the following 3 methods: (1) fifth-order polynomial fitting, (2) locally weighted polynomial regression (LOESS) with smoothing parameter (α) = .25, and (3) LOESS with α = .4. Angle between the 2 tangents along the spinal curve with the most positive and negative slopes (ie, posterior deformity angle) and summation of the angles formed by every 2 lines joining 3 neighboring SPs between the end vertebrae (ie, accumulating angle) were computed to quantify scoliotic deformity. Their performances were compared in terms of their correlation with Cobb angle, test-retest reliability, vulnerability to digitization errors, and accuracy of identifying end vertebrae. ResultsPosterior deformity angle calculated from the spinal curve constructed by LOESS with α = .4 excelled in every aspect of the comparison (ie, Cobb angle, test-retest reliability, vulnerability to digitization errors, and accuracy of identifying end vertebrae and convexity direction), making it the method of choice of those tested for processing the spatial data of the SP tips in this ultrasonography study using dry bone specimens. ConclusionsThe ultrasound-based system and the LOESS (0.4)–posterior deformity angle method developed for this study offer a viable technology for quantifying scoliotic deformity in a reliable and radiation-free manner. However, further validation using scoliosis subjects is needed before they can be used to quantify spinal deformity in the clinical setting.

Automatic Training Sample Selection for a Multi-Evidence Based Crop Classification Approach

Abstract. An approach to use the available agricultural parcel information to automatically select training samples for crop classification is investigated. Previous research addressed the multi-evidence crop classification approach using an ensemble classifier. This first produced confidence measures using three Multi-Layer Perceptron (MLP) neural networks trained separately with spectral, texture and vegetation indices; classification labels were then assigned based on Endorsement Theory. The present study proposes an approach to feed this ensemble classifier with automatically selected training samples. The available vector data representing crop boundaries with corresponding crop codes are used as a source for training samples. These vector data are created by farmers to support subsidy claims and are, therefore, prone to errors such as mislabeling of crop codes and boundary digitization errors. The proposed approach is named as ECRA (Ensemble based Cluster Refinement Approach). ECRA first automatically removes mislabeled samples and then selects the refined training samples in an iterative training-reclassification scheme. Mislabel removal is based on the expectation that mislabels in each class will be far from cluster centroid. However, this must be a soft constraint, especially when working with a hypothesis space that does not contain a good approximation of the targets classes. Difficulty in finding a good approximation often exists either due to less informative data or a large hypothesis space. Thus this approach uses the spectral, texture and indices domains in an ensemble framework to iteratively remove the mislabeled pixels from the crop clusters declared by the farmers. Once the clusters are refined, the selected border samples are used for final learning and the unknown samples are classified using the multi-evidence approach. The study is implemented with WorldView-2 multispectral imagery acquired for a study area containing 10 crop classes. The proposed approach is compared with the multi-evidence approach based on training samples selected randomly and border samples based on initial cluster centroids within agricultural parcels without any refinement. The results clarify the improvement in overall classification accuracy to 82.3 % based on the proposed approach from 74.9 % based on random selection and 71.4% on non-refined border samples.

Study of Common-Mode Voltage Measurements for IEC62684

This paper presents the study of common-mode (CM) voltage measurements for IEC 62684 regulatory. Due to the digitization error caused by the limited vertical bit number of the analog-to-digital converter (ADC) in oscilloscopes, the CM voltage spectrum measurement of the flyback converter with ac source occurs significant inaccuracy. In order to avoid the digitization error, the CM voltage measurement of the flyback converter with dc source is proposed in this paper. The simplified equivalent circuits of the flyback converter with ac and dc input sources are derived to calculate the ratio of their CM voltages. With 64-bit circuit simulation software SIMPLIS, the digitization error can be significantly reduced to have high-resolution measurements for the verification of the calculated CM voltage ratio. The ratio of the calculated CM voltages can be used to modify the measurement result with dc source to obtain the equivalent result with ac source.

A 45 nm 9-bit 1 GS/s High Precision CMOS Folding A/D Converter with an Odd Number of Folding Blocks

In this paper, a 9-bit 1GS/s high precision folding A/D converter with a 45 nm CMOS technology is proposed. In order to improve the asymmetrical boundary condition error of a conventional folding ADC, a novel scheme with an odd number of folding blocks is proposed. Further, a new digital encoding technique is described to implement the odd number of folding technique. The proposed ADC employs a digital error correction circuit to minimize device mismatch and external noise. The chip has been fabricated with 1.1V 45nm Samsung CMOS technology. The effective chip area is 2.99 mm 2 and the power dissipation is about 120 mW. The measured result of SNDR is 45.35 dB, when the input frequency is 150 MHz at the sampling frequency of 1 GHz. The measured INL is within +7 LSB/-3 LSB and DNL is within +1.5 LSB/-1 LSB.

A very fast phase inversion approach for small baseline style interferogram stacks

The recently developed interferometric time-series analysis techniques have shown great potential in ground surface deformation monitoring applications. Such techniques overcome the drawbacks of the traditional differential radar interferometry (DInSAR) and can achieve millimeter-level measurement accuracy. One of the most important operations in interferometric time-series analysis techniques — referred to as phase inversion — is to estimate relative deformation velocity and digital elevation model error from a double-differenced interferometric phase time-series. Unfortunately, current phase inversion methods generally exhibit a low computational efficiency due to their high non-linearity, especially in the case when the dimension of an interferogram stack is large. In this paper, a new approach is proposed to efficiently resolve phase inversion problems defined on stacks constructed by interferograms with small baselines. The approach separates an estimation procedure into two parts. First, preliminary estimates are obtained by weighted least squares. Then, the estimates are refined by optimizing the corresponding ensemble phase coherence function. The proposed approach was applied to simulated and real data. Experimental results demonstrate that it can accurately address the phase inversion problem with a very high computational performance.

A 12-bit 100 MS/s pipelined SAR ADC with addition-only digital error correction

A new redundant successive approximation register (SAR) ADC architecture with digital error correction is presented to avoid the comparator offset issue and subtraction operations. A 2-channel 12-b...

Edge‐based spatial concealment of digital dropout error in degraded archived media

A spatial concealment technique, based on the concept of the strength of an edge, is proposed for ‘digital dropout’ error, evident in old archived media. As long as the presence of pathological motion is observed in video sequences where current state-of-the-art methods fail to reproduce correct information, such spatial restoration offers a much better solution in terms of quality and complexity. Furthermore, relevant edge-based weighted interpolation is able to restore complicated edges and complex textures from the available neighbourhood. An experiment is performed on real video archives to evaluate the efficacy of the proposed technique.

Ontogeny of the female femur: geometric morphometric analysis applied on current living individuals of a Spanish population.

In this study we describe the development of the female femur based on the analysis of high-resolution radiographic images by means of geometric morphometrics, while assessing the usefulness of this method in these kinds of studies. The material analysed consisted of digital images in DICOM format (telemetries), corresponding to 184 left femora in anterior view, obtained from the database of the Hospital Sant Joan de Déu of Barcelona (Spain). Bones analysed corresponded to individuals from 9 to 14 years old. Size and shape variation of the entire femur was quantified by 22 two-dimensional landmarks. Landmark digitisation errors were assessed using Procrustes anova test. Centroid size (CS) variation with age was evaluated by an anova test. Shape variation was assessed by principal component analysis. A mancova test between the first five principal components and age, using the CS as covariable, was applied. Results indicated that both size and shape vary significantly with age. Several age-related shape changes remained significant after removing the allometric effect. In general, an increase in the robustness of the bone and noticeable phenotypic changes in certain areas of the femur were observed. During growth in the proximal region of the femur, the collo-diaphyseal angle decreases, the neck of the femur widens and the fovea moves to a lower position, standing more in line with the plane of the neck. Likewise, the size of the greater and lesser trochanters increase. In the distal region, a significant increase of epiphyseal dimensions was recorded, mainly in the medial condyle. The angular remodelling of the neck and the bicondylar region of the femur in females continues until 13 years old. The information provided in the present study increases our knowledge on the timing and morphology of the femur during development, and in particular the morphology of the different femoral ossification centres during development.

Studies for the development of a virtual permeameter

A systematic analysis on the use of the lattice Boltzmann method (LBM) for predicting the permeability of packed beds is presented. A filtration rig is used to obtain permeability measurements of beds of glass beads, sand and crushed minerals. Subsequently, X-ray micro-tomography is employed to image bed samples for use as input to LBM calculations. Uncertainties in accuracy and reliability of predictions arising from pixel resolution, sample size and digitisation errors in the simulations are evaluated through sensitivity studies and assessments of the representativeness of the bed samples. For beds of spherical and near-spherical particles, any bed sample is capable of providing reproducible and reliable simulation results provided that the particles are adequately resolved within an LBM simulation. For more complex beds of polymorphous, polydisperse particles estimation of the permeability of representative samples of the entire bed is required before average results comparable with data are obtained.

Feasibility Analysis of DC Digital Voltmeter Automatic Test Equipment

This article is based on DC digital voltmeter test procedures requirements (JJG315-83).It aims to use this method to test digital voltmeter error on the basis of AC and DC voltage , current and resistance with automatic test equipment . Systematic error analysis for the relevant verification and standard deviation analysis is done to prove that test error 6 digital voltmeter is feasible with this device .

A 12 bit 200 MS/s Zero-Crossing-Based Pipelined ADC With Early Sub-ADC Decision and Output Residue Background Calibration

A 12 bit 200 MS/s analog-to-digital converter (ADC) applies techniques of zero-crossing-based circuits as a replacement for high-gain high-speed op-amps. High accuracy in the residue amplifier is achieved by using a coarse phase in ZCBC followed by a level-shifting capacitor for fine phase. Sub-ADC flash comparators are strobed immediately after the coarse phase to achieve a high sampling rate. The systematic offset voltage between the coarse and fine phase manifests itself as systematic offset in the sub-ADC comparators. This offset is caused by the coarse phase undershoot and the fine phase overshoot. In this work, the offset is cancelled with background calibration by residue range correction circuits in the following stage's sub-ADC. In addition, the sub-ADC's random comparator offset is calibrated with a discrete-time charge-pump based background calibration technique. The reference buffer, bias circuitry, and digital error correction circuits are all integrated on a single chip. The ADC occupies an area of 0.282 mm $^{2}$ in 55 nm CMOS technology and dissipates 30.7 mW. It achieves 64.6 dB SNDR and 82.9 dBc SFDR at 200 MS/s for a FOM of 111 fJ/conversion-step. The SNDR degrades gracefully above the designed sampling frequency to 62.9 dB at 250 MS/s, and remains above 50 dB at 300 MS/s.

WE-A-17A-03: Catheter Digitization in High-Dose-Rate Brachytherapy with the Assistance of An Electromagnetic (EM) Tracking System

Purpose: To investigate the use of a system using EM tracking, postprocessing and error-detection algorithms for measuring brachytherapy catheter locations and for detecting errors and resolving uncertainties in treatment-planning catheter digitization. Methods: An EM tracker was used to localize 13 catheters in a clinical surface applicator (A) and 15 catheters inserted into a phantom (B). Two pairs of catheters in (B) crossed paths at a distance 4.5 mm (A) and >5.5 mm (B); errors were detected for shifts on average >2.0 mm (A) and >2.4 mm (B). Both mix errors associated with undistinguishable catheter artifacts were detected and at least one of the involved catheters was identified. Conclusion: We demonstrated the use of an EM tracking system for localization of brachytherapy catheters, detection of digitization errors and resolution of undistinguishable catheter artifacts. Automatic digitization may be possible with a registration between the imaging and the EM frame of reference. Research funded by the Kaye Family Award 2012.« less

Computational technique to overcome the limit of a photomask writer

We present the limit of a conventional photomask writer and new possibilities to meet various requirements of tight specifications for a sub-10 nm device. The issues of a variable shaped beam (VSB) writer and how to overcome the limit by computational techniques are discussed. Because VSB writing can use only one rectangular or triangular beam per shot, the complex design for computational lithography results in the increase of shot number to implement rounded or angled pattern. Based on model-based-fracturing, we have confirmed that the ideal curvilinear pattern can be optimized by using overlapping shots, and that they have the same patterning performance in mask and wafer. On the other hand, the multibeam writer can make ideally any kinds of shapes, even curvilinear design because the combination of small spots writes a design. In a real situation, each spot of multibeam writer is defined at fixed mesh and each beam has discrete dose level, so that there are fidelity errors if the pixel size is large or the dose level is not enough large. Here, we propose a “Buddhist cross” design as the evaluation pattern of digitization error in a multibeam writer. The “fidelity error” smaller than 0.5 nm error requires 5 nm pixel size and the required minimum number for dose level is 7 to implement a smaller error than 0.05 nm at one edge. To realize new technology for mass production, new data flow, model based pattern verification, and required computing power have been presented.