Digital Integration Method Research Articles

Theoretical Upper and Lower Limits for Normalized Bandwidth of Digital Phase-Locked Loop in GNSS Receivers.

Determining the loop noise bandwidth and the coherent integration time is essential and important for the design of a reliable digital phase-locked loop (DPLL) in global navigation satellite system (GNSS) receivers. In general, designers set such parameters approximately by utilizing the well-known fact that the DPLL is stable if the normalized bandwidth, which is the product of the integration time and the noise bandwidth, is much less than one. However, actual limit points are not fixed at exactly one, and they vary with the loop filter order and implementation method. Furthermore, a lower limit on the normalized bandwidth may exist. This paper presents theoretical upper and lower limits for the normalized bandwidth of DPLL in GNSS receivers. The upper limit was obtained by examining the stability of DPLL with a special emphasis on the digital integration methods. The stability was investigated in terms of z-plane root loci with and without the consideration of the computational delay, which is a delay induced by the calculation of the discriminator and the loop filter. The lower limit was analyzed using the DPLL measurement error composed of the thermal noise, oscillator phase noise, and dynamic stress error. By utilizing the carrier-to-noise density ratio threshold which indicates the crossing point between the measurement error and the corresponding threshold, the lower limit of the normalized bandwidth is obtained.

Case Study of 137Cs: Optimizing Counting Conditions with Different Background Region Width Selection

Throughout the years, an optimizing counting conditions and optimum background region width determination has been carried out by several methods in gamma-ray spectroscopy. The effect of various background region widths has been the focus on digital integration methods in photopeak analysis. As an application tool of this in nuclear physics, radioactive sources has been mostly used by the lower or the higher resolution detectors; such as NaI(Tl) or HPGe gamma-ray detectors. This resolution factor influences the distinguishability of the peaks in close proximity in spectra. Therefore, a new computational and statistical approach should be implemented to decrease the error factors contributed by one of each bin content, namely the counts, in gamma-ray spectra. At this point, greater precision might be needed and reached in testing different bin region widths on each side of the range of interest for an individual peak. In specific, Gilmore's Total Peak Area (TPA) method will be used here to measure and anaylze the background region width comparisons and their effects in the precision of counting gamma-rays by a NaI(Tl) scintiallation detector.

RFI Mitigation for One-Bit UWB Radar Systems

Radio frequency interference (RFI) mitigation is critical to the proper operation of ultrawideband (UWB) radar systems because RFI can severely degrade the radar imaging capability and target detection performance. In this article, we address the RFI mitigation problem for one-bit UWB radar systems. A one-bit UWB system obtains its signed measurements via a low-cost and high rate sampling scheme, referred to as the continuous time binary value (CTBV) technology. This sampling strategy compares the signal to a known threshold that varies with slow-time and can be used to achieve a high sampling rate and quantization resolution with simple and affordable hardware. This article establishes a proper data model for the RFI sources and proposes a novel RFI mitigation method for the one-bit UWB radar system that uses the CTBV sampling technique. Specifically, we model the RFI sources as a sum of sinusoids with frequencies fixed during the coherent processing interval (CPI) and we exploit the sparsity of the RFI spectrum. We use an extended majorization-minimization-based 1bRELAX algorithm, referred to as 1bMMRELAX, to estimate the RFI source parameters from the signed measurements obtained by using the CTBV sampling strategy. We also devise a new fast frequency initialization method for the extended 1bMMRELAX algorithm to improve its computational efficiency. Moreover, a sparse method is introduced to recover the desired radar echoes using the estimated RFI parameters. Both simulated and experimental results are presented to demonstrate that our proposed algorithm outperforms the existing digital integration method, especially for severe RFI cases.

Application of artificial neural network in neutron/gamma pulse shape discrimination for EJ301 scintillation detector

The scintilator detectors are sensitive to both neutron and gamma radiation. Therefore, right identification of the pulses which generated by neutrons or gamma ray from these detectors plays an important role in neutron measurement by using scintilator detector. In order to improve the ability to pulse shape discrimination (PSD), many PSD techniques have been studied, developed and applied. In this work, we use a basic configuration of a Fully connected Neural network (Fc- Net) where the number of elements of the network is minimum, and each element corresponds to identified specification of neutron or gamma pulses measured by using EJ-301 scintilator detector. The minimum of error principle has been applied for neuron network design; therefore, the accuracy of recognitions did not affect by this reduced network. The obtained results show that the identify accuracy of FcNet is higher than those of digital charge integration (DCI) method. Being tested using 60Co radioactive source, it is shown that, with the application of the FcNet, the accuracy of the gamma pulses discrimination acquires 98.60% in the energy region from 50 to 2000 keV electron equivalent energy (keVee), and 95.59% in the energy region from 50 to 150 keVee. In general, the obtained results indicate that the artificial neural network method can be applied to build neutron/gamma spectrometers with limited hardware.

A Connective Framework to Support the Lifecycle of Cyber–Physical Production Systems

The potential benefits of the adoption of cyber-physical production systems (CPPSs) and their significant role in enabling smart manufacturing is well recognized today. However, it is less clear how such CPPS can be most effectively and consistently engineered and maintained throughout their lifecycle due to the existing divide in the information technology (IT) and operational technology (OT) landscape and ad hoc integration practices that result in inconsistent data and data models at various levels of manufacturing processes. The work presented in this article addresses this problem by envisioning a connective framework to support the engineering of CPPS through the use of a set of digital twins consistent with the real system throughout its lifecycle, not just used in the design and deployment phases. A review of the latest perspectives on using digital integration frameworks, methods, and solutions for lifecycle engineering of CPPS is provided in this article. This article demonstrates how a suitable framework, named SIMPLE, can be realized to effectively address the lack of consistent data models throughout the engineering lifecycle, including implementation details and example cases developed by the authors at the Warwick Manufacturing Group (WMG) in selected industrial sectors. Consideration is given to supporting cyber-to-physical systems' connectivity and extendable engineering toolsets, forming the basis for multidisciplinary digital engineering environments. Key discussion points include the role and importance of effective integration of IT and OT, suitable frameworks for integration and collaboration.

Application of correlation pattern recognition technique for neutron– gamma discrimination in the EJ-301 liquid scintillation detector

The ability to distinguish between neutrons and gamma-rays is important in the fast - neutron detection, especially when using the scintillation detector. A dual correlation pattern recognition (DCPR) method that was based on the correlation pattern recognition technique has been developed for classification of neutron/gamma events from a scintillation detector. In this study, an EJ-301 liquid scintillation (EJ301) detector was used to detect neutrons and gamma-rays from the 60Co and 252Cf sources; the EJ301 detector's pulses were digitized by a digital oscilloscope and its pulse-shape discriminant (PSD) parameters were calculated by the correlation pattern recognition (CPR) method with the reference neutron and gamma-ray pulses. The digital charge integration (DCI) method was also used as a reference-method for comparison with DCPR method. The figure-ofmerit (FOM) values which were calculated in the 50 ÷ 1100 keV electron equivalent (keVee) region showed that the DCPR method outperformed the DCI method. The FOMs of 50, 420 and 1000 keVee thresholds of DCPR method are 0.82 , 2.2 and 1.62, which are 1.55, 1.77, and 1.1 times greater than the DCI method, respectively.

Implementation of a Fast and Low-Power Thermopile Readout Circuit Arrangement for Array Processors

High-speed thermal imaging is necessary in many applications. However, the traditional column-wise readout implementations reduce the achievable frame rate. Also, analog integration for each individual pixel is not possible without sacrificing pixel area. In this brief, we present an implementation of a fast and low-power pixel-wise readout circuit scheme with a digital integration method using 65-nm standard CMOS technology. The power consumption of the readout circuit is up to $15~\mu{\text{W}}$ and the layout area is $100~{\mu }\text{m} {\times } 100~{\mu }\text{m}$ . Furthermore, we analyze our design for non-idealities, such as noise and process mismatches using a circuit simulator.

Precise digital integration in wide time range: theory and realization

The digital integration method based on using high-speed precision analog-to-digital converters (ADC) has become widely used over the recent years. The paper analyzes the limitations of this method that are caused by the signal properties, ADC sampling rate and noise spectral density of the ADC signal path. This analysis allowed creating digital integrators with accurate synchronization and achieving an integration error of less than 10−5 in the time range from microseconds to tens of seconds. The structure of the integrator is described and its basic parameters are presented. The possibilities of different ADC chips in terms of their applicability to digital integrators are discussed. A comparison with other integrating devices is presented.

Toward a fractal spectrum approach for neutron and gamma pulse shape discrimination*Supported by the National Natural Science Foundation of China (41274109), Sichuan Youth Science and Technology Innovation Research Team (2015TD0020), Scientific and Technological Support Program of Sichuan Province (2013FZ0022), and the Creative Team Program of Chengdu University of Technology.

Accurately selecting neutron signals and discriminating γ signals from a mixed radiation field is a key research issue in neutron detection. This paper proposes a fractal spectrum discrimination approach by means of different spectral characteristics of neutrons and γ rays. Figure of merit and average discriminant error ratio are used together to evaluate the discrimination effects. Different neutron and γ signals with various noise and pulse pile-up are simulated according to real data in the literature. The proposed approach is compared with the digital charge integration and pulse gradient methods. It is found that the fractal approach exhibits the best discrimination performance, followed by the digital charge integration method and the pulse gradient method, respectively. The fractal spectrum approach is not sensitive to high frequency noise and pulse pile-up. This means that the proposed approach has superior performance for effective and efficient anti-noise and high discrimination in neutron detection.

Precision digital signal integrators with accurate synchronization

This paper presents the VsDC2 and VsDC3 multifunctional integrators developed at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences for measurements of both constant and pulsed magnetic fields. These integrators are based on the digital integration method which provides an error smaller than 10−5 for a wide class of measurements. The method used in the developed devices allows accurate synchronization of an integration interval with pulsed signals, while the ADC used in the measuring channel is clocked by an asynchronous and low clock frequency. The theoretical aspects of the proposed solutions are considered and compared with known methods of constructing digital integrators. The circuitry of these devices is briefly described, and the main characteristics are given.

Dynamic displacement sensing, system identification, and control of a speaker-based tendon vibrator via accelerometers

In this paper, we develop a speaker-based tendon vibrator capable of applying vibrations with sustained amplitudes and desired time-frequency profiles to be used in inducing kinesthetic illusions. For modeling and control of the tendon vibrator, we propose and experimentally validate a method for real-time dynamic displacement sensing based on accelerometers. We tested the accuracy of displacement measurements by comparing the movements of the vibrator measured with differential accelerometers to those measured by a high resolution optical encoder. We completed frequency domain system identification of the vibrator and obtained a parametric transfer function model via displacements sensed by the encoder and by analog and digital integration. We show that within the frequency range of interest 20 -100 Hz, analog and digital integration methods were successful in capturing an accurate model of the vibrator. Under feedforward control, developed tendon vibrator is able to generate sustained 2-mm peak-to-peak vibrations throughout the frequency range of interest.

The Research for Work Roll Thermal Deformation of Cold Rolling Mill with Plastic Materials

In this article, the factors which have influence on the work roll thermal deformation in cold strip rolling and the heat transferring mechanism are discussed. It is considered that there are three direc-tions, radial、axis and circumference, for heat transferring for work roll thermal deformation with plastic materials. Therefore, it is a three dimensions unstable system for work roll temperature field of cold strip rolling. The plastic deformation work and friction heat are calculated by the divided element and digital integration method. The simplified calculation model is built for the heat trans-ferring along work roll. There are four zones for work roll heat transferring: roll gap zone、air zone、emulsion zone、rolls contact zone. The heat transferring between the zones is decided by the temperature difference. The inter temperature field and thermal deformation of work roll can be calculated by two-dimension finite difference method. The work roll temperature and thermal crown of actual application cold rolling mill are analyzed by the model. By the comparison between calculated values and measured values, the work roll thermal calculation model can meet the accu-racy requirement of on-line control.

Work Roll Thermal Deformation Calculation Model of Cold Rolling Mill

In this article, the factors which have influence on the work roll thermal deformation in cold strip rolling and the heat transferring mechanism are discussed. It is considered that there are three directions, radial, axis and circumference, for heat transferring for work roll thermal deformation. Therefore, it is a three dimensions unstable system for work roll temperature field of cold strip rolling. The plastic deformation work and friction heat are calculated by the divided element and digital integration method. The simplified calculation model is built for the heat transferring along work roll. There are four zones for work roll heat transferring: roll gap zone, air zone, emulsion zone, rolls contact zone. The heat transferring between the zones is decided by the temperature difference. The inter temperature field and thermal deformation of work roll can be calculated by two-dimension finite difference method. The work roll temperature and thermal crown of actual application cold rolling mill are analyzed by the model. By the comparison between calculated values and measured values, the work roll thermal calculation model can meet the accuracy requirement of on-line control.

Die Bedeutung der digitalen Integrationsmethode (DIM) von OCT und FLA für die klinische Anwendung

We describe the establishment of a new digital integration method (DIM) for the anatomically precise and objective correlation of OCT and FLA. The aim of the study was to evaluate the clinical impact of DIM and deduce possible new knowledge in unclear angiographic findings. DIM uses a newly developed software for the integration of OCT and FLA images of the same date. Corresponding vascular bifurcations and OCT scan position are marked in OCT and FLA images. Pathological areas in OCT or FLA can be marked and compared. A fundus enhancement system (FES) was developed for a better fundus image quality in OCT. Using a retinal tracking system (RTS) eye movements can be compensated. DIM was evaluated in 225 patients with macular diseases. Using FES, the DIM was successful in 95 % of the patients in contrast to 25 % without FES. Using the video system of RTS eye movement artefacts could be compensated in all patients. Cases with clear angiographic findings showed a high correspondence (66 %) with the OCT findings. A discrepancy between FLA and OCT findings was found in 33 %, especially in leakages of unknown origin. DIM was of high value in age-related macular degeneration (AMD), detecting a heterogeneous morphology of serous, solid RPE detachments, retinal cystoid formation and choroidal neovascularisation (CNV) and differentiating it in a precise topography. The lesion size of classic CNV with a hypofluorescent halo was in OCT always larger than in FLA. Through the correction of the eye movement artefacts by DIM and FES, a fundamental weak point in the previous OCT pictures is counterbalanced. Using DIM the OCT scan position for the follow-up can now be assessed in a safe and reliable manner which is mandatory for the evidence of OCT studies. The detection of precise morphology (serous RPE detachments) in angiographically unclear phenomena can lead to treatment consequences, e. g., avoiding contraindicated areas in photodynamic therapy. Using the new morphological information new knowledge is obtained on uncertain angiographic phenomena by this integration method (DIM).

Clinical relevance of the new digital integration method for the precise correlation of fluorescein angiographic and optical coherence tomography findings

A fundamental weak point in the previous optical coherence tomography (OCT) pictures of Stratus OCT III is counterbalanced through the correction of eye movement artefacts by the new digital integration method (DIM). For the first time, DIM allows the precise anatomical OCT-scan localization in the fundus or fluorescein angiographic (FLA) image and leads to an objective morphological and topographic correlation. Using a newly developed fundus enhancement system (FES), DIM provides fundus images of OCT of high quality in almost every patient. To control and document any possible eye movement artefacts, a retinal tracking system was developed (RTS). The RTS tapes the fundus image in OCT during the scanning procedure. Using the new morphological information a new knowledge is obtained on uncertain angiographic phenomena by detecting serous retinal pigment epithelium (RPE) detachments and may lead to treatment consequences. In FLA images without leakages DIM reveals in OCT undetected serous RPE detachments. In addition, in 100% classic choroidal neovascularization (CNV) with a hypofluorescent halo DIM demonstrates a larger extent of the CNV than expected in FLA. Using DIM the OCT-scan position for the follow-up can be now assessed in a safe and reliable manner, which is mandatory for the evidence of OCT studies.

The combined investigation of the flame dynamics of an industrial gas turbine combustor using high-speed imaging and an optically integrated data collection method

In this paper, innovative investigation of the flame dynamics of an industrial gas turbine combustor using high-speed imaging and flame luminosity measurement has been reported. Both digital and optical integration methods have been applied to study the flame dynamics of an unstable combustion mode, which has a fixed peak frequency around 105 Hz. It is found that the light emission of the seeded combustion possesses the same dominant peak frequency as the acoustic emission. On the other hand the natural flame light emission failed to match the spectrum of the acoustic emission due to signal drop-out, which is a common problem for direct imaging of unseeded flame. The paper has demonstrated that the transition from stable to unstable combustion could be captured successfully by high-speed imaging using a pre-trigger mode. Three stages of transition from stable combustion mode to unstable mode have been identified. In stage one, the flame luminosity and fluctuation increased gradually, which could be assumed as the incipiency of the instability. In stage two, there was a sudden and sharp burst in flame luminosity, which indicates that the combustion process was becoming very intense in the middle of transition. In the third stage, the drastic flame luminosity dissipated slightly and oscillated with constant amplitude and the combustion locked to unstable combustion mode. The two applied techniques have been cross-checked with reference to the unique peak frequency observed.

Digital simulation models of a capacitor voltage transformer

Mathematical models for two kinds of capacitor voltage transformer (CVT) with various states, i.e., zero load state, normal load state, short-circuit state of the primary side, and short-circuit state of the secondary side are presented. Digital simulation models of the CVT corresponding to the various states by using an adequate digital integration method are developed. Using the basis of these models, a digital simulation of the CVT on a PC is conveniently realized and transient characteristics of the CVT are researched on a PC according to the national lab standard, GB4703, of PR China. Details are demonstrated with the aid of a numerical example. The results indicate that the mathematical models and the digital simulation models are in good agreement.

Digital real-time simulation of a high-voltage short distance ring power transmission system

In this paper a multiple modular mathematical model of a high-voltage short ring power transmission system fit for digital real-time simulation is presented. Various states on this system have been simulated including regular operation states, different types of faults at different distances and operation of switches under faults. The results running on a Pentium II 333 show that the presented model and the given digital integration method are correct and can be realized in real-time.

A real-time digital simulation model of the electromagnetic transients in power transmission systems by parallel processing using multiple modules

Parallel processing has been widely employed in real-time digital simulation of power transmission systems. This paper presents a new model using multiple modules and its integration method. According to this model and the given digital integration method a digital example simulation is carried out covering the following operating phases: electromagnetic and electromechanical transients after connecting a synchronous machine to the idle double-circuit high-voltage three-phase power transmission line (DHTT), automatic synchronization of the synchronous machine at the far end of the DHTT, parallel operation of the power transmission system (a DHTT with synchronous machines at both ends). The results show that the new model is fit for real-time digital simulation of this system.

Automated Assessment of Mitral Regurgitant Volume and Regurgitant Fraction by a Newly Developed Digital Color Doppler Velocity Profile Integration Method

Recent development of the automated cardiac flow measurement (ACFM) method has provided automated measurement of stroke volume and cardiac output by spatial and temporal integration of digital Doppler velocity profile data. The purpose of this study was to evaluate the clinical usefulness of the ACFM method using digital color Doppler velocity profile integration in the assessment of mitral regurgitant volume and regurgitant fraction from measurements of both aortic outflow and mitral inflow volumes. We calculated both aortic outflow and mitral inflow volumes from the apical approach with the ACFM and pulsed Doppler (PD) methods in 20 patients with isolated mitral regurgitation. Mitral regurgitant volume and regurgitant fraction were calculated by the following equation: mitral regurgitant volume = (mitral inflow volume) − (aortic outflow volume), % regurgitant fraction = (mitral regurgitant volume)/(mitral inflow volume) × 100. Mitral regurgitant volume and regurgitant fraction were compared with that determined by the PD method. Mitral regurgitant volume measurement by the ACFM method showed a good correlation with that measured by the PD method (r = 0.90, y = 0.77x + 11.6, SEE = 9.0 ml); the mean differences between PD and ACFM measurements was −1.7 ± 12.5 ml. Regurgitant fraction estimated by the ACFM method correlated well with that of the PD method (r = 0.92, y = 0.98x + 2.1, SEE = 8.8%). The mean difference for the measurement of regurgitant fraction between the PD and ACFM methods was 0.8 ± 6.6%. Total time required for mitral regurgitant volume calculation in 1 cardiac cycle by the ACFM method was significantly shorter than that of the PD method (126 ± 15 seconds vs 228 ± 36 seconds, p <0.01). In conclusion, the newly developed ACFM method is simple, quick, and accurate in the automated assessment of mitral regurgitant volume and regurgitant fraction.