Standard Deviation Of Measurements Research Articles

THE POSITIVE INFLUENCE OF IMAGES AND GRAPHICS PRESENTATIONS IN TEACHING TEXTS FOR KEEPING STUDENTS' ATTENTION AND CONCENTRATION

We live in a world where visuals are becoming very important, as most information is presented as acombination of words and pictures which provide the opportunity to create concrete and abstract ideas for readingthrough the formation of images in the mind. Everything in the world is a photo. The written (text) is a photo, andthe photo represents a text. Visual literacy is the ability to use images to construct meaning. The advantages ofsymbols have long been recognized, which is why we are increasingly incorporating symbolic teaching and learningtoday. Using words and images allows the thought process to be visible, that is, it allows us to put ideas on paper,out of the brain, where we can explore them more deeply. Since visualization is considered a factor that directlyaffects the level of understanding and retention of students’ attention, many remarks addressed the inclusion of thiscomponent in the preliminary books. To gather experience and findings about the impact of the inclusion of imagesand visual representations on the attention of students, a questionnaire was carried out with teachers who worked inthe lower primary cycle. However, since the research problem has to do with the positive impact of these visualshows on maintaining the students' attention, direct observation of the students was also carried out. The researchwill reveal data and qualitative analysis obtained from the observation of students of the lower primary cycle of twoschools in the cities of Tetovo, Skopje, Gostivar, and Kiçevo, one of which is a school in the city and one in thevillage. The retention of students' attention has been compared using books that are supported by visual andcontrasting images. The data collected from the statements collected from the questionnaires and qualitative datacollected from the observation are analyzed with statistical procedures and methods. The arithmetic mean was usedto describe the quantitative data obtained from this research. To measure the variability of the data, the standarddeviation measure was used, a t-test of statistical significance and ANOVA were used to determine the differencesbetween the groups, while the Pearson correlation coefficient was used to determine the relationship between thevariables. The results obtained about this complicated and active act, prompt many questions, but also support manyconclusions that cause different associations and suggest many solutions presented in the relevant research in theform of suggestions.

Awareness of Periodontal Disease And its Influence on Systemic Health: A Survey Among Medical Professionals in State of Rajasthan (bikaner Subdivision).”

Background: Since past few decades, it is established that periodontitis has powerful influence on various systemic conditions. To maintain general health among the medical professionals this bidirectional link between periodontal and systemic health should be acquainted. 
 Aims: To evaluate knowledge, awareness and orientation of medical professionals towards periodontal diseases and its influence on systemic health in state of Rajasthan (Bikaner sub division). To aware medical professionals for overall improved health care delivery system and motivate referrals to periodontists in systemically ill patients.
 Method and Material: Prepared questionnaire data was gathered from 503 medical professionals of various medical institutions in state of Rajasthan (Bikaner sub division). Study spanned from June 2019 to August 2019. Data was tabulated in Microsoft Excel sheet and subjected to statistical analysis. Mean and standard deviations of measurements per group were calculated, and differences between two groups were determined using chi square test.
 Results: Majority of participants had basic knowledge regarding periodontal diseases but clinical orientation and practice behavior were very limited. Most of them were aware regarding systemic effects of periodontal diseases like chronic heart diseases, diabetes but were unaware of likely effects of periodontal diseases on conditions such as adverse pregnancy outcomes (PTLBW, PROM, and Preeclampsia) and hospital acquired pneumonia.
 Conclusion: Medical practitioners had insufficient knowledge and limited clinical orientation about periodontal diseases and its potential influence on systemic conditions. This emphasizes need for periodontal education in medical field.

Accuracy and reproducibility of effective atomic number and electron density measurements from sequential dual energy CT.

This study assesses the accuracy of effective atomic number (Zeff ) and electron density measurements acquired from dual energy CT and characterizes the response to clinically relevant variables representative of challenges in patient imaging, including: phantom size, material position within the phantom, variation over time, off-center positioning, and large cone beam angle. The Gammex Multi-Energy CT head and body phantoms were used to measure Zeff and electron density from 35 rod inserts that mimic tissues and varying concentrations of iodine and calcium. Scans were performed on a Canon Aquilion ONE Genesis CT scanner over a period of 6months using default dual energy protocols appropriate for each phantom size. Theoretical Zeff and electron density values were calculated using data provided by the phantom manufacturer and compared to the measurements. Sources of variance were separated and quantified to identify the influences of random photon statistics, ROI placement, and variation over time. A subset of measurements were repeated with the phantom shifted in the vertical and horizontal directions, and over all slices in the volumetric scan. All measurements showed strong correlation (r>0.98) with their corresponding theoretical values; however, the system did demonstrate a bias of -0.58 atomic units in the body phantom and 0.28 atomic units in the head phantom for Zeff measurements. The mean absolute percent error (MAPE) was 6.3% for the body phantom and 3.2% for the head phantom. Electron density measurements of the body and head phantoms gave MAPE values of 4.6% and 1.0%, respectively. Zeff and electron density measurements significantly varied within the solid water background, showing a positional dependence within the phantom that dominated the total standard deviation in measurements. Zeff values dropped by 0.2 atomic units when the phantom was off-center; electron density measurements were less affected by phantom position. Along the z-axis, the accuracy drops off markedly at more than 50-60mm from the central slice. The Canon dual energy system offers an accurate way of measuring the Zeff and electron density of clinically relevant materials. Accuracy could be improved further by calibration to remove bias, careful attention to centering within the FOV, and avoiding measurements at the edges of the cone beam.

An Accelerometer-Based Sensing System to Study the Valve-Gaping Behavior of Bivalves

Bivalves are extremely sensitive to environmental conditions. The movement of their shells and the gap in-between the valves can serve as indicators of water pollutants entering surface water bodies. This letter proposes a novel sensing system to accurately calculate the valve-gaping angle in bivalves. The sensor unit is comprised of two inertial measurement units for each bivalve to estimate the angle between the two valves. Monitoring of multiple bivalves is possible with several water-insulated sensor units tethered with flexible cables to a central base station housing the processing unit. Miniaturization of the sensor packaging and flexibility of the wires ensured minimum hindrance to the animals’ natural behavior. The precision and accuracy of the angle measurement were tested with a benchtop servo motor setup simulating the gaping behavior. The standard deviation of measurements at a steady state was 0.78 $^\circ$ , and the average change in measurement during a 10 $^\circ$ step was 9.98 $^\circ$ . Over 250 h of in vivo validation experiments demonstrated the consistency of the angle measurements using the presented method alongside a magnetic alternative, which had an average correlation coefficient of $-$ 0.89. The sensor system provides an accurate study of bivalve gaping behavior and facilitates the potential use of bivalves as environmental sentinels due to their valve-gaping being a biomarker for monitoring water pollution.

Responsive navigation of a biped robot that takes into account terrain, foot-reachability and capturability

A control architecture for robust biped navigation that takes into account traversability on terrain, foot-reachability, and capturability all at once in dynamic situations is proposed. It consists of online mapping of terrain and quick decision of foot placement. A grid map with elevation, normal direction and the standard deviation of measurement is proposed for the former and is named the stochastic Elevation-and-Normal Grid (ENG) map. It is incrementally updated as depth sensor information comes in every cycle. The traversability of each grid can be easily checked based on the associated information. The latter stands upon the canonical biped track (CBT), which is a pair of continuous paths that the feet track. It is drawn along a nominal collision-free path on the ENG map. The most efficient foot placement at the next step from the viewpoint of the foot-reachability is chosen on them as the initial candidate, around which a feasible placement accommodated with traversability and capturability is found by the breadth-first search. An autonomous biped locomotion system is completed by combining the above architecture with a foot-guided controller based on the terminal capturability. The efficacy of the proposed method was validated through some computer simulations.

Timescales of emergence of chronic flooding in the major economic center of Guadeloupe

Abstract. Sea-level rise due to anthropogenic climate change is projected not only to exacerbate extreme events such as cyclones and storms but also to cause more frequent chronic flooding occurring at high tides under calm weather conditions. Chronic flooding occasionally takes place today in the low-lying areas of the Petit Cul-de-sac marin (Guadeloupe, West Indies, French Antilles). This area includes critical industrial and harbor and major economic infrastructures for the islands. As sea level rises, concerns are growing regarding the possibility of repeated chronic flooding events, which would alter the operations at these critical coastal infrastructures without appropriate adaptation. Here, we use information on past and future sea levels, vertical ground motion, and tides to assess times of emergence of chronic flooding in the Petit Cul-de-sac marin. For RCP8.5 (Representative Concentration Pathway 8.5; i.e., continued growth of greenhouse gas emissions), the number of flood days is projected to increase rapidly after the emergence of the process so that coastal sites will be flooded 180 d a year within 2 decades of the onset of chronic flooding. For coastal locations with the lowest altitude, we show that the reconstructed number of floods is consistent with observations known from a previous survey. Vertical ground motions are a key source of uncertainty in our projections. Yet, our satellite interferometric synthetic-aperture radar results show that the local variability in this subsidence is smaller than the uncertainties in the technique, which we estimate to be between 1 (standard deviation of measurements) and 5 mm/yr (upper theoretical bound). Despite these uncertainties, our results imply that adaptation pathways considering a rapid increase in recurrent chronic flooding are required for the critical port and industrial and commercial center of Guadeloupe. Similar processes are expected to take place in many low-elevation coastal zones worldwide, including on other tropical islands. The method used in this study can be applied to other locations, provided tide gauge records and local knowledge of vertical ground motions are available. We argue that identifying times of emergence of chronic flooding events is urgently needed in most low-lying coastal areas, because adaptation requires decades to be implemented, whereas chronic flooding hazards can worsen drastically within years of the first event being observed.

Determining Optimal Resolution for Scanned Document Raster Content

Modern scan routines require a predefined scan resolution, whether it is customer-selected or a default value in the scanner’s settings. When the scanning process begins, the resolution cannot be changed. This results in all scanned pages, no matter how much their contents may vary, having output images of the same size. If we can determine an optimal resolution for each scanned document raster content, we can save a lot of storage. In this paper, the resolutions in question are 300 dpi, 150 dpi, and 75 dpi. We define the criteria for optimal scan resolution and propose some new features to help determine it for scanned document raster content. The features proposed are sample power spectrum mean squared error (MSE), edge density, and edge contrast. These features can reflect the truthfulness between high-resolution 300 dpi images (references) and their lowresolution (150 dpi and 75 dpi) counterparts and the intrinsic changes among them. Combining them with spatial activity, tile standard deviation (STDDEV) structural similarity index measure mean (tile-STDDEV SSIM), and tile STDDEV structural similarity index measure STDDEV (tile-STDDEV SSIM STDDEV), we can form a feature vector, which is then fed into an SVM classifier. Test result shows that we can achieve a prediction accuracy of 93.4%.

Wireless Sensor Network Localization Using AoA Measurements With Two-Step Error Variance-Weighted Least Squares

We propose a novel localization method using angle-of-arrival (AoA) measurements with two-step error variance-weighted least squares (TELS). The first step is to estimate a terminal location provisionally using least squares. The second step is to estimate the terminal location using weighted least squares, with the weights for each anchor and each evaluation-function term, calculated from the error variance based on the first step. The proposed method does not require previous information on the environment while achieving high performance. The simulation results indicate that a root mean square error (RMSE) of the proposed method is superior to that of the existing hybrid received signal strength (RSS)/AoA localization methods. When 11 anchors are deployed inside a cube with edge length 15 m, and the standard deviations of measurements are small, the RMSE of the proposed method reaches about 0.34 m. It is nearly equal to that of Cramer-Rao lower bound (CRLB) on AoA.

Evidence for Possible Systematic Underestimation of Uncertainties in Extragalactic Distances and Its Cosmological Implications

We analyse 91,742 reported extragalactic distance moduli and their uncertainties for all 14,560 galaxies with multiple reported distances in the NED Redshift-Independent Distances database. For each ordered pair of distance moduli measurements 1 and 2 for each galaxy, we define Δ(σ)[1, 2], a measure for how different measurement 2 is in relation to measurement 1, as a multiple of the estimated standard deviation in measurement 1. We then take a mean of all such Δ(σ)[1, 2] in a given category to come up with an estimate for the average separation between measurements as a multiple of the average reported uncertainty in that category. For normally distributed measurements, the expected value of Δ(σ) is 1.13. Our results are as follows. The mean Δ(σ) of all 1,239,062 ordered pairs of extragalactic distance moduli is 2.07 corresponding to a p-value of 3.85%. This indicates a possible systematic underestimation of uncertainties in extragalactic distances. We also find that the mean one sigma reported uncertainty decreased and the mean Δ(σ) increased from 1991-2018. This points to increased underestimation of uncertainties with time. For the latest period 2011-2018 with 26,509 reported extragalactic distance moduli for 7,812 galaxies, the mean Δ(σ) of 124,840 ordered pairs is 2.72 corresponding to a p-value of 0.65%. For 14,888 extragalactic distance moduli of 2,518 galaxies measured using Type Ia Supernovae, the mean Δ(σ) for 124,016 ordered pairs is 2.85 corresponding to a p-value of 0.44%. This may have some implications for our confidence in cosmological parameters and models. We conclude that more liberal estimation of uncertainties in future reported extragalactic distances should be considered. The results also give a possible way out of the Hubble tension by advocating for increasing the error bars on Hubble-Lemaitre constant measured via distance ladders of standard candles and rulers.

PSVIII-31 Sources of variations, repeatability and reproducibility of microbial count data

Abstract The current study consists of two separate experiments to evaluate the relative contribution of systematic factors to the total variability of count data using same silage inoculant. In experiment-1, two lots of a raw material were used to prepare three batches of media. Each of three technicians weighed five independent samples per day, over 10 days and worked on their samples through dilution, plating, and counting. Each sample was grown on three plates. In experiment-2 technician effect was further evaluated at weighing-diluting, plating and counting subprocesses. Each technician weighed and diluted three independent samples per day, over three days. Samples were then shared between technicians during plating and counting. Count data were converted to log10 values and data in experiment-1 were analyzed using a random effects model that included lot, batch, technician, day, and sample within lot-batch-day-technician. Model for experiment-2 included similar effects, except technician effect was partitioned into weighing-diluting technician, plating technician, and counting technician, and there were no batch and lot effects. In experiment-1 sampling variance accounted for a relatively large proportion of the total variance (35%) followed by 33% due to technician effects. The overall repeatability standard deviation of count data was 0.08. Reproducibility standard deviation of measurements made by different technicians on the same day was 0.12. Reproducibility standard deviation of microbial count by the same technician at different days was 0.10. Contribution of sampling variance remained the highest in experiment-2 (39%). The total technician variance was mainly due to weighing-diluting technician, contributing to 31% of the total variance. The relatively large contribution of sample-to-sample variance suggests a major improvement in the precision of count data may be obtained through additional samples rather than increasing number of plates per sample. Technician training can further help reduce variation and improve consistency in sample weighing and dilution.

A CMM-Based Method of Control Point Position Calibration for Light Pen Coordinate Measuring System.

A light pen coordinate measuring system (LPCMS) is a kind of vision-based portable coordinate measuring technique. It implements coordinate measurement by analyzing the image of a light pen, which has several control points and a probe. The relative positions of control points need to be determined before measurement and serve as the measuring basis in LPCMS. How to accurately calibrate the relative positions of control points is the most important issue in system calibration. In this paper, a new method of control point position calibration based on a traditional coordinate measuring machine (CMM) is proposed. A light pen is fastened to the measuring arm of a CMM and performs accurate translational movement driven by the CMM. A camera is used to capture the images of control points at different positions, and the corresponding readings of the CMM are recorded at the same time. By establishing a separate coordinate system for each control point, the relative positions of the control points can be transformed to the differences of a series of translation vectors. Experiments show that the calibration repeatability of control point positions can reach 10 μm and the standard deviation of measurement of the whole LPCMS can reach 30 μm. A CMM is used to generate accurate translation, which provides a high accuracy basis of calibration. Through certain mathematical treatment, tremendous data acquired by moving the light pen to tens of thousands of different positions can be processed in a simple way, which can reduce the influence of random error. Therefore, the proposed method provides a high-accuracy solution of control point position calibration for LPCMS.

The Paradox of Precision

This paper is about a typical mistake in the calculation of standard deviation of measurements in cases in which there are no differences among repetitious replicates. Some students believe the standard deviation in those case is equal to zero. So, this mistake leaves to a paradox: worse balance should show better results (i.e. standard deviation equal to zero). The solution of this simple, but important situation is shown. DOI: http://dx.doi.org/10.17807/orbital.v12i2.1466

Field-compatible protocol for detecting tetracyclines with bioluminescent bioreporters without pipetting steps.

Whole-cell bioreporters are living organisms and thus using them for detecting environmental contaminants would reflect biological effects of these pollutants. However, bioreporters are not widely used in field studies. Many of the bioreporter field protocols are suitable for liquid samples or include pipetting steps, which is a demanding task outside the laboratory. We present a bioreporter protocol without pipetting or sample type requirements. The protocol utilizes polyester swabs, commonly used in cleanroom technology. As an example contaminant, we used tetracycline and generated test samples with known concentrations up to the maximum tetracycline residue limit of milk set by the European Union (EU) regulation. The matrices of the test samples were Milli-Q water, milk and soil. The swabs were first dipped in the bioreporter cell cultures and then to test samples and luminescence was measured after incubation. The standard deviation of measurements from ten replicate swabs was in the same range as commonly in pipetting protocols (4-19%). The test samples with lowest tetracycline concentration (5ng mL-1 ) were distinguished from the control samples (0ng mL-1 tetracycline). Our results show that swabs can be used together with luminescent whole cell bioreporters, making it possible to conduct the measurements in field conditions.

Fabrication and Characterization of a High-Performance Multi-Annular Backscattered Electron Detector for Desktop SEM.

Scanning electron microscopy has been developed for topographic analysis at the nanometer scale. Herein, we present a silicon p-n diode with multi-annular configuration to detect backscattering electrons (BSE) in a homemade desktop scanning electron microscope (SEM). The multi-annular configuration enables the enhancement of the topography contrast of 82.11 nA/μm as compared with the commercial multi-fan-shaped BSE detector of 40.08 nA/μm. Additionally, we integrated it with lateral p-n junction processing and aluminum grid structure to increase the sensitivity and efficiency of the multi-annular BSE detector that gives higher sensitivity of atomic number contrast and better surface topography contrast of BSE images for low-energy detection. The responsivity data also shows that MA-AL and MA p-n detectors have higher gain value than the MA detector does. The standard deviation of measurements is no higher than 1%. These results verify that MA p-n and MA-AL detectors are stable and can function well in SEM for low-energy applications. It is demonstrated that the multi-annular (MA) detectors are well suited for imaging in SEM systems.

Signal-to-noise ratios, instrument parameters and repeatability of Itrax XRF core scan measurements of floodplain sediments

This study used signal-to-noise ratios to assess the effects of increasing Itrax XRF instrument parameters, namely tube voltage, tube current and exposure time, on XRF spectra and measurement repeatability. Tests were performed on cores from British and Irish floodplains. Seven combinations of tube voltage and current and six exposure times were compared using signal-to-noise ratios for eight target elements. Signal-to-noise ratios may be substantially improved by selecting instrument parameters, particularly tube voltage, for specific target elements. They can also be used to assess element profile suitability for interpretation by comparison with the limit of quantification. Repeatability was assessed using the standard deviation of measurements in nine repeat scans. The variation in element levels in the majority of profiles is considerably greater than the variability in individual measurements.

Use of a MEMS accelerometer to measure orientation in a geotechnical centrifuge

Microelectromechanical systems (MEMS) accelerometers are becoming more prevalent in geotechnical engineering and geotechnical centrifuge modelling. In centrifuge experiments these sensors have shown great promise, but still exhibit limitations. This paper proposes a new methodology for the use of single-axis, low-g, high-accuracy MEMS accelerometers to measure the orientation of an object on the vertical rotational plane of centrifugal acceleration and Earth's gravity in a geotechnical centrifuge. The method specifically compensates for the measured cross-axis acceleration by an MEMS accelerometer when in a high-g environment. This is done by determining the apparent internal misalignment of the MEMS sensing unit, relative to its packaging, from a high-g cross-axis calibration. The misalignment can then be used to correct the measured orientation of the sensor relative to a centrifuge gravity vector. When compared to simplified approaches, measurements of absolute orientation are improved by 0·89° and the standard deviation of measurements between multiple sensors is reduced by 0·71°. Overall, this new methodology significantly improves the accuracy of orientation measurements by MEMS accelerometers in the geotechnical centrifuge, opening the door to use these inexpensive sensors in more experiments.

Shielding Effect and Guarding in High Resistance Measurement

Generally, electric and magnetic interference will affect in high resistance measurements. This causes a large number of the standard deviation of measurement as well as the accuracy and result of measurement. The purpose of this research is to study the effectiveness of shielding and guarding on the measurement system. In experimental setup, the 1 GΩ resistance was supplied by voltage source of 100 V, 500 V and 1000 V in with and without shielding and guarding. The resistance value and standard deviation were measured and compared in each case of measurements. From the experimental results, when applying shielding and guarding, the noise can be reduced. As a result, the standard deviation was decreased more than 10 times.

Simple tunable dual-wavelength fiber laser and multiple self-mixing interferometry to large step height measurement.

A simple tunable dual-wavelength fiber laser was developed and multiple self-mixing interferometry to large step height measurement was demonstrated. The fiber laser, which can emit two wavelengths without laser mode competition, is composed of a single fiber ring cavity and two fiber branches. Each branch includes a length of erbium-doped fiber and a fiber Bragg grating. Large step heights can be measured using multiple self-mixing interference of the two wavelengths. The maximum height that can be measured is half synthetic wavelength of the two wavelengths. A step height of 2mm constructed with two gauge blocks has been measured. The standard deviation of measurement results is 2.5nm.

(Invited) Parameter Identification in Electrochemical Impedance Spectroscopy Applications: Analysis of Sensitivity

EIS is a powerful non-destructive technique that can access essential information about interfacial and bulk material parameters through the use of low energy time varying electrical excitations. When applied to an electrochemical system, IS can provide information on reaction parameters, corrosion rates [1], oxide characteristics, porosity, coating integrity [2-3], mass transport, and many other electrode/interface characteristics [4]. Software packages for the analysis of impedance data have also emerged [5–7]. The typical goal of an EIS experiment is to gather significant information regarding the physicochemical phenomena taking place in an electrochemical system, and the experimental data are then compared to a model that describes the system. The model can be purely empirical, being composed of resistors, capacitors, and generalized electrochemical elements, or otherwise it can be based on the physics of the system. Model parameters are evaluated through an inverse method. Minimization algorithms such as the Complex Non Linear Least Squares (CNLS) method, the Gauss-Newton method, the Levenberg-Marquardt method or the Downhill Simplex algorithm are used to determine the value of the parameters that minimize the sum of squared differences between the experimental and predicted data. Regardless of the method, the minimum value of the χ2 statistic is commonly used to assess the quality of the regression. χ2 is a non-weighted sum of squared differences: (1) In this equation, nf, Re, Im and |Z| represent the total number of frequencies constituting the impedance spectrum, the real and imaginary part and the modulus of the impedance, respectively. The subscripts e and c stand for the experimental and the calculated data, respectively. The standard deviation for the measurement is assumed to be Z= 0.01.|Ze| i.e.assuming a standard deviation for the impedance measurement of 1% of the modulus. For a complex regression, the fitting quality was determined by the standard deviation q. (2) Where n is the degree of freedom for the regression, i.e., the number of observations 2nf minus the number of adjustable parameters. The Smaller χ2 , the smaller the differences between the observed and modeled values and the better the fit. It is generally considered that a fit if satisfactory if the value of q is of the order of 1. A value smaller than 1 means that error was overestimated. χ2 provides a useful single numerical value for assessing the quality of the regression, but χ2does not provide any information on the accuracy of the different parameters evaluated. It is important to know if and how much the model, and subsequently the χ2or q are sensitive to the different parameters. Hence the sensitivity to the different parameters provides information on the accuracy of the identification technique. In this communication, we will show the results of the sensitivity analysis performed on three model cases: a blocking electrode and the ferri/ferrocyanide system, silicon nitride thin layers. Confidence intervals (sensitivity) for the fitted parameters were estimated empirically from the change (of +/- 5%) in a single parameter value yielding an increase of the standard deviation q characterizing the fit quality, the other parameters staying fixed to their optimal value or unfixed in order to estimate interactions between parameters. Basically, if a confidence interval is very wide, the data doesn’t define that parameter very well, or that the model proposed is not optimum. If a confidence interval is very narrow, this parameter becomes an important parameter in the overall model. This approach is helpful in order to evaluate the robustness of the model and to validate the physical interpretation of model Parameters. Keywords: electrochemical impedance spectroscopy, regression model, sensitivity, confidence interval References [1] Srisuwan, N., Ochoa, N., Pébère, N., Tribollet, B., Corrosion Science, Volume 50, Issue 5, May 2008, p 1245-1250 [2] NACE 2012 March 11 – Technology Exchange Group 097X, Electrochemical Measurements [3] Introduction to Corrosion Science, E. McCafferty [4] M.E. Orazem, B. Tribollet, Electrochemical Impedance Spectroscopy, The Electrochemical Society, Series, Ed. Wiley, 2008. [5] B.A. Boukamp, Solid State Ionics 18–19 (1986) 136. [6] J.R. Macdonald, L.D. Potter Jr., Solid State Ionics 24 (1987) 61. [7] J.R. Macdonald, CNLS (Complex Nonlinear Least Squares) lmmittance Fitting, Program LEVM Manual, Houston, TX, Version 7.11 Edition, 1999. Figure 1

Enabling real-time ultrasound imaging of soft tissue mechanical properties by simplification of the shear wave motion equation.

Ultrasound based shear wave elastography (SWE) is a technique used for non-invasive characterization and imaging of soft tissue mechanical properties. Robust estimation of shear wave propagation speed is essential for imaging of soft tissue mechanical properties. In this study we propose to estimate shear wave speed by inversion of the first-order wave equation following directional filtering. This approach relies on estimation of first-order derivatives which allows for accurate estimations using smaller smoothing filters than when estimating second-order derivatives. The performance was compared to three current methods used to estimate shear wave propagation speed: direct inversion of the wave equation (DIWE), time-to-peak (TTP) and cross-correlation (CC). The shear wave speed of three homogeneous phantoms of different elastic moduli (gelatin by weight of 5%, 7%, and 9%) were measured with each method. The proposed method was shown to produce shear speed estimates comparable to the conventional methods (standard deviation of measurements being 0.13 m/s, 0.05 m/s, and 0.12 m/s), but with simpler processing and usually less time (by a factor of 1, 13, and 20 for DIWE, CC, and TTP respectively). The proposed method was able to produce a 2-D speed estimate from a single direction of wave propagation in about four seconds using an off-the-shelf PC, showing the feasibility of performing real-time or near real-time elasticity imaging with dedicated hardware.