Reduce Measurement Time Research Articles

Pulse Width Modulation for Reducing Pulsed MOS Capacitor Measurement Time

Carrier lifetime in silicon is a direct measure of its deep-level defect density. This parameter is therefore widely used for process screening purposes to check for unwanted contaminations such as metallic impurities. The dynamics of semiconductor industry requires the development of novel approaches to reduce the measurement time of commonly established carrier lifetime measurement techniques for more efficient screening in process lines. The pulsed MOS capacitor (MOS-C) is the most popular technique for measuring the generation lifetime (τg ) where τg is being extracted from the capacitance transient response (C-t) of a MOS capacitor device when pulsed from accumulation into deep-depletion and as it moves from the non-equilibrium deep-depletion into the inversion. Although accurate and easy to implement, the pulsed MOS capacitor takes a long time to accomplish. For clean wafers the time for a single measurement can easily reach several hours. This becomes specifically problematic when the goal is to map the whole wafer area. Many attempts have been made to reduce the lifetime measurement times. The challenge, however, is to maintain the accuracy while trying to reduce the test time. It will showed that by using a dynamic pulse train and exploiting the pulse width, the pulsed MOS-C technique can be implemented not only to reduce the measurement time. If the accumulation pulse in the pulsed MOS technique is applied at a high frequency the device response will become substantially short resulting in a reduced measurement time. Interestingly, this approach will not cause any compromise in the accuracy with which the lifetime is measured. TCAD simulations and experimental results will be presented to show the effect of the accumulating pulse width on the C-t transient of a typical MOS device.

Enhancing the quantification of tissue sodium content by MRI: time-efficient sodium B1 mapping at clinical field strengths.

Tissue sodium content (TSC) is a sensitive measure of pathological changes and can be detected non-invasively by MRI. For the absolute quantification of TSC, B1 inhomogeneities must be corrected, which is not well established beyond research applications. An in-depth analysis of B1 mapping methods which are suitable for application in TSC quantification is presented. On the basis of these results, a method for simultaneous B1 mapping and imaging is proposed in order to enhance accuracy and to reduce measurement time at clinical field strengths. The B1 mapping techniques used were phase-sensitive (PS), Bloch-Siegert shift (BSS), double-angle (DAM) and actual flip-angle imaging (AFI) methods. Experimental and theoretical comparisons demonstrated that the PS technique yields the most accurate field profiles and exhibits the highest signal-to-noise ratio (SNR). Simultaneous B1 mapping and imaging was performed for the PS method, employing both degrees of freedom of the MR signal: the B1 field is encoded into signal phase and the amplitude provides the concentration information. In comparison with the more established DAM, a 13% higher SNR was obtained and field effects could be corrected more accurately without the need for additional measurement time. The protocol developed was applied to measure TSC in the healthy human head at an isotropic resolution of 4 mm. TSC was determined to be 35 ± 1 mM in white matter and 134 ± 3 mM in vitreous humor. By employing the proposed simultaneous characterization of the B1 field and acquisition of the spin density-weighted sodium signal, the accuracy of the non-invasive measurement of TSC is enhanced and the measurement time is reduced. This should allow (23)Na MRI to be better incorporated into clinical studies and routine.

Multi-frequency simultaneous measurement of bioimpedance spectroscopy based on a low crest factor multisine excitation

Bioimpedance spectroscopy (BIS) is becoming a powerful diagnostic tool for a wide variety of medical applications, and the multi-frequency simultaneous (MFS) measurement of BIS can greatly reduce measurement time and record the transient physiological status of a living body compared with traditional frequency-sweep measurement technology. This paper adopts the Van der Ouderaa’s multisine, which has 31 equidistant and flat amplitude spectra and a low crest factor of 1.405 as the broadband excitation, and realizes the MFS measurement of BIS by means of spectral analysis using the fast Fourier transform algorithm. The approach to implement the multisine based on a field-programmable gate array and a digital to analog converter is described in detail, and impedance measurement experiments are performed on three resistance-capitance three-element phantoms. Experimental results show a commendable accuracy with a mean relative error of 0.55% for the impedance amplitudes, and a mean absolute error of 0.20° for the impedance phases on the 31 frequencies ranging linearly from 32 to 992 kHz. This paper validates the feasibility of the MFS technology for BIS measurement based on the multisine excitation.

Towards Fast In-line Measurement of Water Activity

Water activity is widely used as a key parameter in controlling the quality of food and feed products, among others. For determining the water activity, the material is sampled from the manufacturing process and measured in the laboratory with water activity analyzers. The sampling procedure can lead to non-representative measurements, the measurement process is time consuming, and much of the produced material may be wasted before the measurement results are available. To reduce waste and to be able to optimize production processes, industry requires in-line measurement of relevant quality determining parameters, hereunder the water activity. In cooperation with a manufacturer of systems for automatic in-line sampling and measurement of moisture, density, and the size of items, a project was defined to also enable the manufacturer’s existing products to perform automatic measurement of the water activity in a sample. The aim was to develop a measurement system with the ability to operate in an industrial environment, which in the end would increase the measurement speed significantly and minimize the problems related to the handling of samples. In the paper the selection and characterization of the sensors, the design of a measurement chamber, and various issues of modeling and methods to reduce measurement time are discussed. The paper also presents water activity measurements obtained from food and feed products with the system, and shows that reliable results can be obtained in a few minutes with a proper design of the measurement chamber and selection of a model.

A home-made system for IPCE measurement of standard and dye-sensitized solar cells.

A home-made system for incident photon-to-electron conversion efficiency (IPCE) characterization, based on a double-beam UV-Vis spectrophotometer, has been set up. In addition to its low cost (compared to the commercially available apparatuses), the double-beam configuration gives the advantage to measure, autonomously and with no need for supplementary equipment, the lamp power in real time, compensating possible variations of the spectral emission intensity and quality, thus reducing measurement times. To manage the optical and electronic components of the system, a custom software has been developed. Validations carried out on a common silicon-based photodiode and on a dye-sensitized solar cell confirm the possibility to adopt this system for determining the IPCE of solar cells, including dye-sensitized ones.

Enhanced OCV prediction mechanism for a stand-alone PV-lithium ion renewable energy system

This paper aims to improve the estimation of state of charge (SoC) of the battery component for a small-scale photovoltaic stand-alone system through the use of a simple summing equation, at a set measurement interval. The system uses a predefined parameter to accurately predict the open-circuit voltage (OCV) of a cell at a much reduced measurement time of 5 minutes, while maintaining a maximum prediction error of less than 1%SoC. A simulation model has been provided that allows measurement of the cell voltage and current for prediction of the equilibrated OCV. The simulation can be used for single cell, modules and battery packs which use lithium-based technologies. Validation of the model has been performed using experimental data from tests conducted at the Centre for Automotive and Power System Engineering (CAPSE) laboratories, at the University of South Wales. An application has been proposed for this work, which includes a photovoltaic module for energy generation to power an illuminated advertizing sign. The energy is stored in a lithium-based battery model which uses a combination of a battery management system and remote monitoring for real-time data acquisition.

Assessment of a three-dimensional (3D) water scanning system for beam commissioning and measurements on a helical tomotherapy unit.

Beam scanning data collected on the tomotherapy linear accelerator using the TomoScanner water scanning system is primarily used to verify the golden beam profiles included in all Helical TomoTherapy treatment planning systems (TOMO TPSs). The user is not allowed to modify the beam profiles/parameters for beam modeling within the TOMO TPSs. The authors report the first feasibility study using the Blue Phantom Helix (BPH) as an alternative to the TomoScanner (TS) system. This work establishes a benchmark dataset using BPH for target commissioning and quality assurance (QA), and quantifies systematic uncertainties between TS and BPH. Reproducibility of scanning with BPH was tested by three experienced physicists taking five sets of measurements over a six‐month period. BPH provides several enhancements over TS, including a 3D scanning arm, which is able to acquire necessary beam‐data with one tank setup, a universal chamber mount, and the OmniPro software, which allows online data collection and analysis. Discrepancies between BPH and TS were estimated by acquiring datasets with each tank. In addition, data measured with BPH and TS was compared to the golden TOMO TPS beam data. The total systematic uncertainty, defined as the combination of scanning system and beam modeling uncertainties, was determined through numerical analysis and tabulated. OmniPro was used for all analysis to eliminate uncertainty due to different data processing algorithms. The setup reproducibility of BPH remained within 0.5 mm/0.5%. Comparing BPH, TS, and Golden TPS for PDDs beyond maximum depth, the total systematic uncertainties were within 1.4 mm/2.1%. Between BPH and TPS golden data, maximum differences in the field width and penumbra of in‐plane profiles were within 0.8 and 1.1 mm, respectively. Furthermore, in cross‐plane profiles, the field width differences increased at depth greater than 10 cm up to 2.5 mm, and maximum penumbra uncertainties were 5.6 mm and 4.6 mm from TS scanning system and TPS modeling, respectively. Use of BPH reduced measurement time by 1–2 hrs per session. The BPH has been assessed as an efficient, reproducible, and accurate scanning system capable of providing a reliable benchmark beam data. With this data, a physicist can utilize the BPH in a clinical setting with an understanding of the scan discrepancy that may be encountered while validating the TPS or during routine machine QA. Without the flexibility of modifying the TPS and without a golden beam dataset from the vendor or a TPS model generated from data collected with the BPH, this represents the best solution for current clinical use of the BPH.PACS number: 87.56.Fc

Sodium magnetic resonance imaging using ultra-short echo time sequences with anisotropic resolution and uniform k-space sampling

A method for uniform k-space sampling of 3D ultra-short echo time (UTE) techniques with anisotropic resolution in one direction is introduced to increase signal-to-noise ratio (SNR). State-of-the-art acquisition schemes for sodium MRI with radial (projection reconstruction) and twisting (twisted projection imaging (TPI)) trajectories are investigated regarding SNR efficiency, blurring behavior under T2⁎ decay, and measurement time in case of anisotropic field-of-view and resolution. 3D radial and twisting trajectories are redistributed in k-space for UTE sodium MRI with homogeneous noise distribution and optimal SNR efficiency, if T2⁎ decay can be neglected. Simulations based on Voronoi tessellations and phantom simulations/measurements were performed to calculate SNR efficiency. Point-spread functions were simulated to demonstrate the influence of T2⁎ decay on SNR and resolution. Phantom simulations/measurements and in vivo measurements confirm the SNR gain obtained by simulations based on Voronoi cells. An increase in SNR of up to 21% at an anisotropy factor of 10 could be theoretically achieved by TPI with projection adaption compared to the same sequence but without redistribution of projections in k-space. Sodium MRI with anisotropic resolution and uniform k-space sampling is demonstrated by in vivo measurements of human intervertebral disks and heart at 3 T. The SNR gain can be invested in a measurement time reduction of up to 32%, which is important especially for sodium MRI.

ABOUT DETERMINING THE POSITION OF THE GEOGRAPHIC MERIDIAN THREE-STAGE PENDULUM GYROCOMPASS DURING ACCELERATION OF ITS ROTOR

The article considers three-stage pendulum gyrocompass ground with torsion suspension unmanaged sensor, equipped with high-precision digital angle sensor azimuthal position sensor and information processing unit. During processing of information isused an indirect method to get facts about initial deviations of dynamical systems.In the process of improving the instrument have revealed that a further increasing of accuracy due to the necessity to consider the following factors. During the measurement around the vertical axis of the sensor operates permanent uncontrolled moment due to operational reasons are different from measurement to measurement. Specified point shifts the center of oscillation of the azimuthal sensor, which is in accordance with the procedure identified azimuth northerly direction on a constant value. For self-compensation of this error have been proposed several methods based on measurements with different but fixed parameters of the device. However, these measures have extended more than twice the measurement process.In this article there is proposing to define the position of the geographic meridian based on the analysis of the azimuthal motion sensor gyro during acceleration of its rotor. The proposal can bring dual gain in reducing measurement time: at first, the rotor becomes "staff " rather than ballast gyro operation mode, as it was before; secondly, there is no need for special measures to combat harmful vertical moments, as the shift of the equilibrium caused by the action of the latter, is variable in time, which allows to determine the magnitude of harmful moment during a single measurement.

Improved Compressive Sampling SFCW Radar by Equipartition of Energy Sampling

A Stepped-Frequency Continuous Wave (SFCW) radar performs imaging by transmitting a number of electromagnetic tones whose frequency is increased step-wisely to obtain an equivalent representation of a signal in frequency domain, then Fourier inversion is conducted to obtain a range profile. A Compressive Sampling (CS) SFCW radar reduces measurement time by randomly selecting a small number of the tones, followed by CS reconstruction. This paper shows empirically, that the knowledge of typical magnitude spectrum of the radar's signal can be used to improve the CS-SFCW radar system in term of either better reconstruction quality or less number of required samples. Instead of random selection, the knowledge of the spectrum is used to select the best set of frequencies, by applying equipartition of energy sampling (EES) principle. Three sampling schemes, i.e., Frequency Equidistant Sampling (FES), Uniform Random Sampling (URS), and the proposed EES, are used to obtain the samples of both simulated and actual A-scan data and then identical CS reconstruction methods are applied. Objective performance evaluation in term of PSNR (Peak Signal to Noise Ratio) shows that reconstructed result of URS outperforms the FES, while the EES outperforms both of them.

Preparing for SwissFEL: Exploring the limits of time-resolved X-ray spectroscopy

Using x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) to probe laser-excited samples we can obtain excited-state structural and electronic dynamical information not available through other techniques.[1] One of the restrictions of most synchrotron-based implementations of this technique is the three-orders of magnitude mismatch between x-ray and laser repetition rates (MHz Vs. kHz). By using a laser capable of generating significant pulse energies at MHz repetition rates we can eliminate this discrepancy, thus greatly reducing measurement times and enhancing achievable signal-to-noise ratios.[2] Several examples that demonstrate the strength of this technique will be presented, including probing the electron relaxation in photoexcited TiO2 nanoparticles in solution and resolving the dynamical structural changes associated with ligand rebinding in the protein myoglobin under physiological conditions. The ability to extend these types of measurements into the femtosecond regime at Experimental Station A[3] at the SwissFEL hard X-ray free electron laser, which is under construction at the Paul Scherrer Institute (Villigen, Switzerland), will be discussed.

CDM-Based <inline-formula> <tex-math notation="TeX">\(\lambda \) </tex-math></inline-formula>-OTDR for Rapid TDM- and WDM-PON Monitoring

A novel OTDR-system is introduced, which enables a significant reduction of measurement times in TDM- and WDM-PON measurements compared to a conventional \(\lambda \) -OTDR. It has the ability to measure multiple wavelengths simultaneously with just one receiver photodiode. The working principle is similar to a code division multiplexing transmission system. Furthermore, the measurement time is not only reduced by the simultaneous measurements on different wavelengths but also by means of coding gain, which reduces the OTDR averaging time. The coding gain has its origin in the correlation of signals based on complete complementary codes. In an experiment, measurements were performed, which provided results 15 times faster than with a conventional \(\lambda \) -OTDR. Further improvements are possible with different measurement parameters.

Qualification of ECM-Processes by Electro Impedance Spectroscopy

Electrochemical machining (ECM) is an appropriate technology for structuring a wide range of metals and alloys independent of their mechanical properties. Further advantages the occurence of no tool wear and almost no change in the material properties of the work piece material due to the machining. As different studies showed it is possible to manufacture structures in the µm-range and also in the sub µm-range. The resulting geometry and feature size depend on the electrolyte, the working gap, the electric field, the flow conditions within the working gap and the material structure. The working gap is the most important parameter regarding the critical dimensions of ECM. Actual high resolution processes are limited by the process time due low current densities, while faster processes are limited by the resolution due to the dimensions of the double layer and the need for purging.\\Regarding these limits an enhanced understanding of the electrochemical processes within the working gap is mandatory for the optimization of the ECM. Therefore a measurement device is realised utilising electrochemical impedance spectroscopy (EIS), which is one technique to obtain a wide set of thermodynamic and kinetic parameters related to the electrochemical processes like reactions, adsorption, desorption and diffusion in the gap. There the impedance, which is the complex ratio between the voltage and the current in an AC circuit, is measured as a function of the frequency and it is compared to an equivalent circuit, composed out of basic elements representing the chemical sub processes. The spectrometer is realized by combining a commercial potentiostat with computer based signal processing realized in MATLAB\copyright. The spectrometer implements time-domain measurement techniques (Fourier transformation) for a strong reduction of measurement time. This time reduction allows in situ measurements.\\The presented spectrometer enables characterization of standard material systems like cooper, as well as the identification of the time-critical chemical processes and steps in more complex systems.

Quantum Thermometry

In this review article we revisit and spell out the details of previous work on how Berry phase can be used to construct a precision quantum thermometer. An important advantage of such a scheme is that there is no need for the thermometer to acquire thermal equilibrium with the sample. This reduces measurement times and avoids precision limitations. We also review how such methods can be used to detect the Unruh effect.

Efficacy of Biphasic Transcranial Electric Stimulation in Intraoperative Motor Evoked Potential Monitoring for Cervical Compression Myelopathy

Retrospective analysis of prospectively collected data from consecutive patients undergoing 2 methods of transcranial electrical motor evoked potential (TCE-MEP) monitoring during cervical spine surgery. To investigate the efficacy of biphasic transcranial electric stimulation, the deviation rate, amplitude of TCE-MEPs, complications, and sensitivity and specificity of TCE-MEP monitoring were compared between the biphasic and conventional monophasic stimulation methods. With biphasic stimulation, unlike monophasic stimulation, measurement time can be reduced considerably because a single stimulation elicits bilateral responses almost simultaneously. However, no study has yet reported a detailed comparison of the 2 methods. Examination 1: Amplitude and derivation rate of TCE-MEPs was compared for monophasic and biphasic stimulation in the same 31 patients with cervical compression myelopathy. Examination 2: Sensitivity, specificity, and complications of TCE-MEP monitoring were compared in 200 patients with cervical compression myelopathy who received monophasic or biphasic stimulation (100 patients each) during intraoperative monitoring. Examination 1: Derivation rates of biphasic stimulation in the deltoid, biceps brachii, abductor digiti minimi, and flexor hallucis brevis muscles were the same or higher than for monophasic stimulation. TCE-MEP amplitudes elicited by biphasic stimulation compared with monophasic stimulation were significantly larger in the biceps (paired t, P < 0.0001), but similar in the other 3 muscles. Examination 2: In the biphasic and monophasic stimulation groups, warnings were issued to surgeons in 10 and 11 cases, for a sensitivity of 100% for both groups and specificity of 97.8% and 96.7%, respectively. No complications related to stimulation were observed in any of the 200 patients. Biphasic stimulation had similar or higher derivation rates and equivalent sensitivity and specificity than monophasic stimulation. No complications were observed for either stimulation method. Biphasic stimulation is an effective TCE-MEP monitoring method for cervical spine surgery that may also reduce measurement time. 4.

Particle characterization system for industrial and naval applications

Abstract The Interferometric Particle Imaging (IPI) technique was modified and adapted to provide particle size and particle concentration measurements in harsh environments. The development was forced by the challenge of nuclei concentration measurement in cavitation tunnels and full scale measurements in the wake flow of a vessel. Because only bubbles act as cavitation nuclei, discrimination between bubbles and other solid particles in the multi-phase flow is necessary. The size measurement and classification and can be realized by defocussed imaging and analysis of the scattered light from particles. A few measurement results demonstrate the feasibility of the new developed Nuclei Concentration Measurement (HDNC) technique and there advantages in terms of robustness, moderate hardware effort and reduced measurement time.

Representative Elementary Length to Measure Soil Mass Attenuation Coefficient

With increasing demand for better yield in agricultural areas, soil physical property representative measurements are more and more essential. Nuclear techniques such as computerized tomography (CT) and gamma-ray attenuation (GAT) have been widely employed with this purpose. The soil mass attenuation coefficient (μ s) is an important parameter for CT and GAT analysis. When experimentally determined (μ es), the use of suitable sized samples enable to evaluate it precisely, as well as to reduce measurement time and costs. This study investigated the representative elementary length (REL) of sandy and clayey soils for μ es measurements. Two radioactive sources were employed (241Am and 137Cs), three collimators (2–4 mm diameters), and 14 thickness (x) samples (2–15 cm). Results indicated ideal thickness intervals of 12–15 and 2–4 cm for the sources 137Cs and 241Am, respectively. The application of such results in representative elementary area (REA) evaluations in clayey soil clods via CT indicated that μ es average values obtained for x > 4 cm and source 241Am might induce to the use of samples which are not large enough for soil bulk density evaluations (ρ s). As a consequence, ρ s might be under- or overestimated, generating inaccurate conclusions about the physical quality of the soil under study.

Sub-sampling low coherence scanning interferometry and its application: refractive index measurements of a silicon wafer

In this investigation, refractive indices of a silicon (Si) wafer were measured by low-coherence scanning interferometry adopting the sub-sampling technique to reduce measurement time. Based on Fourier domain analysis method, the sub-sampled correlogram was analyzed and the refractive indices were calculated by the simple refractive index model and curve fitting of the phase extracted from the sub-sampled correlogram. In the experiment to verify the proposed technique, near-infrared light emitted by a super-luminescent diode with 1050nm center wavelength was used as an optical source because it is partially transparent to an undoped Si wafer. As the result of measuring an undoped double-side polished Si wafer, group and phase refractive indices were successfully obtained with the sub-sampled correlogram, and the deviations from the reference value were within 0.001.

Near Infrared Reflectance Spectroscopy (NIRS) for rapid determination of biochemical methane potential of plant biomass

Determination of biochemical methane potential (BMP) by fermentation tests is time-consuming and costly, and therefore not useful for operators of full-scale biogas digesters. A great advantage of NIRS in determining BMP is the reduction in measurement time from at least one month for chemical determination to a couple of minutes for production of near infrared spectroscopy (NIRS) spectra. An innovative NIRS method that can be used as an alternative to current BMP tests was developed in this study. We tested the Partial Least Squares (PLS) model for a rapid determination of BMP using NIRS by applying a series of pre-processing methods with caution. A total of 88 plant biomass samples of a wide variety were used for model prediction. The standard error of the best PLS model was 37 CH4 NLkg−1 VS, where BMP of the test set was between 136.2 and 477.9 CH4 NLkg−1 VS. Coefficient of determination (R2) and residual prediction deviation (RPD) were 0.84 and 2.49, respectively. This shows that the new NIRS model is moderately successful in application and could be an alternative modern tool to overcome the problems of current BMP methods.

Lengthened Simplex Codes With Complementary Correlation for Faulty Branch Detection in TDM-PON

This letter demonstrates a novel coding technique to accurately detect the faulty branch in time-division-multiplexing passive optical network (TDM-PON) infrastructure. The notion relies on encoding the probe signal with a novel composite structure coding technique to achieve the advantages of improved signal-to-noise ratio and resolution, reduced measurement time, and simplified complexity of branch identification. Proof-of-concept experiments on a constructed 1 × 32 TDM-PON with 20 km feeder fiber have been demonstrated, the experimental results are consistent with theoretical results and confirm the key advantages.