Low Measurement Precision Research Articles

Deep Hybrid State Network With Feature Reinforcement for Intelligent Fault Diagnosis of Delta 3-D Printers

An echo state network (ESN) is a type of recurrent neural network that is good at processing time-series data with dynamic behavior. However, the use of ESNs to enhance fault-classification accuracy continues to be challenging when the condition signals are collected by low-cost sensors. In this paper, a deep network algorithm, called a deep hybrid state network (DHSN), is proposed for fault diagnosis of three-dimensional printers using attitude data with low measurement precision. In the DHSN, the output data of a sparse auto-encoder are regarded as the abstract features of a double-structured ESN (DESN). The DESN is designed for feature reinforcement and fault recognition, wherein the first function reinforces the features and the second is used for fault classification. More specifically, feature reinforcement is developed to improve the clustering performance and replace the traditional overall feedback fine-tuning in deep models. This strategy improves learning efficiency and overcomes the vanishing-gradient problem for deep learning. The forecasting performance of the proposed approach is evaluated in experiments, and its superiority is demonstrated through comparison with other intelligent fault-diagnosis technologies.

Validation of the short assessment of health literacy (SAHL-D) and short-form development: Rasch analysis

BackgroundAccurate measurement of health literacy is essential to improve accessibility and effectiveness of health care and prevention. One measure frequently applied in international research is the Short Assessment of Health Literacy (SAHL). While the Dutch SAHL (SAHL-D) has proven to be valid and reliable, its administration is time consuming and burdensome for participants. Our aim was to further validate, strengthen and shorten the SAHL-D using Rasch analysis.MethodsAvailable cross-sectional SAHL-D data was used from adult samples (N = 1231) to assess unidimensionality, local independence, item fit, person fit, item hierarchy, scale targeting, precision (person reliability and person separation), and presence of differential item functioning (DIF) depending on age, gender, education and study sample.ResultsThirteen items for a short form were selected based on item fit and DIF, and scale properties were compared between the two forms. The long form had several items with DIF for age, gender, educational level and study sample. Both forms showed lower measurement precision at higher health literacy levels.ConclusionsThe findings support the validity and reliability of the SAHL-D for the long form and the short form, which can be used for a rapid assessment of health literacy in research and clinical practice.

An improved method for the sealed-tube zinc graphitization of microgram carbon samples and 14C AMS measurement

Advances in accelerator mass spectrometry (AMS) and environmental chemistry techniques have increased demand for the natural abundance 14C analysis of ultra-small (<25 µgC) and compound-specific samples. The sealed-tube zinc (Zn) method is used for the reduction of sample CO2 to graphite on an iron catalyst. This method provides reliable, low AMS 14C backgrounds and high measurement precision over a wide range of sample sizes (1000 µgC to <15 µgC). Recently, Rinyu and co-workers demonstrated improved ion beam currents and 14C backgrounds when performing sealed-tube Zn graphitization by applying a thermal gradient (from room temperature to 550 °C) on 25–100 µgC samples [1]. However, many compound-specific radiocarbon analysis (CSRA) measurements are limited to smaller sample sizes – often <10 µgC per analyte with repeated collection by gas or liquid chromatography. Using a similar thermal gradient setup, we present an improved sealed-tube Zn method for the graphitization of samples ranging from ultra-small mass (2 µgC) and up to 100 µgC in the Keck Carbon Cycle AMS facility (KCCAMS) at the University of California, Irvine. Our improved method produces high AMS currents (he12C+ ∼1 µA µgC−1), a low extraneous C blank (0.5–0.7 µgC), high measurement precision (2–10% as relative % error) and accuracy (95–97%, as an absolute % difference of measured vs. consensus fraction modern values) for modern 2–5 µgC samples. These improvements have resulted in a sealed-tube Zn method which equals the performance of the ultra-small mass H2 reduction method for 2–10 µgC samples [2].

The importance of gene-environment interactions in human obesity.

The worldwide obesity epidemic has been mainly attributed to lifestyle changes. However, who becomes obese in an obesity-prone environment is largely determined by genetic factors. In the last 20years, important progress has been made in the elucidation of the genetic architecture of obesity. In parallel with successful gene identifications, the number of gene-environment interaction (GEI) studies has grown rapidly. This paper reviews the growing body of evidence supporting gene-environment interactions in the field of obesity. Heritability, monogenic and polygenic obesity studies provide converging evidence that obesity-predisposing genes interact with a variety of environmental, lifestyle and treatment exposures. However, some skepticism remains regarding the validity of these studies based on several issues, which include statistical modelling, confounding, low replication rate, underpowered analyses, biological assumptions and measurement precision. What follows in this review includes (1) an introduction to the study of GEI, (2) the evidence of GEI in the field of obesity, (3) an outline of the biological mechanisms that may explain these interaction effects, (4) methodological challenges associated with GEI studies and potential solutions, and (5) future directions of GEI research. Thus far, this growing body of evidence has provided a deeper understanding of GEI influencing obesity and may have tremendous applications in the emerging field of personalized medicine and individualized lifestyle recommendations.

Data Fusion Algorithm Research Based on Multi Scout Radar Networking

Considering the shortcoming of low measurement precision of single scout radar in battlefield, this paper advances the scheme of multi scout radar networking. Aiming at the core problem of networking data fusion of multi scout radars, this paper conducts research and advances data fusion algorithm based on polar coordinate system. This paper provides the realization flow of data fusion algorithm and pays more attention to the problem of coordinate conversion, error calculation, weight determination and data synthesis based on weight, and advances solution. Finally, taking five radars networking for example, conducts simulation experiment and result analysis, and the results shows that whether the fusion precision of distance data or the azimuth data all has greater improvement than measurement data.

Characteristic of Longitudinal Coupled Prefabricated Slab Track (LCPBT): Numerical Simulation Analysis of Uneven Sub Grade Performance

With in the development of high-speed railway countrys China is one of the competent use of ballast less track spreader and largely applied on sub grade, in order to ensure high speed, safe and comfortable run of the train, the sub grade structure must provide smoother and more stable support for the upper track structure, but the problems caused by non uniformity sub grade structure performance are increasingly prominent. There have many serious problems such as low precision of measurement, low degree of automation, compaction mechanism, sometimes consolidation time and high interference of human factors. This paper described as the structural characteristics of longitudinal coupled prefabricated slab track System similar to bögl from German, a model for static analysis has been developed. Based on the model, the slab track element is presented. This element includes rail, rail fastening, prefabricated slab, CA mortar, and base plate and sub grade.

An Analysis to Observations of the Superconducting Gravimeter at the Jiufeng Seismic Station, Wuhan

AbstractThe relationship between the mass transfer in the Earth and vertical deformation can be studied using continuous relative gravimetry and continuous GPS observations. Compared to mobile relative gravimetry and absolute gravimetry, continuous relative gravimetry permits to monitor the whole process of gravity changes and mass transfer, avoiding the problems from low measurement precision and temporal resolution. In this paper, more than 13000 hours gravity data recorded at the Jiufeng seismic station using the superconducting gravimetry (SGC053) are analyzed along with the data of co‐located absolute gravimetry, air pressure, vertical displacement of surrounding GPS stations, WUHN IGS site and WHJF site, GRACE monthly time‐variable gravity and two global continental water storage models (GLDAS, CPC). Gravity variations affected by solid earth tide, air pressure, pole tide and continental water loading are corrected using the harmonic analysis method, atmospheric pressure admittance model, pole tide model and the correlation analysis with GRACE results and/or water storage models, then instrument drift is also corrected using co‐located absolute gravity measurements. Based on the above processing, the relationship between the residual gravity time series and GPS vertical deformation is addressed. The harmonic analysis result for SGC053 gravity records, spanning about one and half years, shows that the white noise is about (1.14~1.40)×10–8 m·s–2 and the tidal factor error of dominant tidal groups reach about 0.10/00. Compared to ocean tide loading (3×10–8 m·s–2), the gravity due to air pressure (12×10–8 m·s–2) and pole tide (10×10–8 m·s–2) is much large. The drift of SGC053, about 2.18×10–8(m·s–2)/a, is estimated using 4 absolute gravity co‐located records of FG5‐232. The result shows that the residual gravity caused by continental water loading in summer and autumn is about (6~8) × 10–8 m·s–2, by comparing residual gravity variations with both GARCE result and global continental water loading (GLDAS, CPC). Gravity variations corrected by water loading show a perfect negative correlation with the vertical deformation of the GPS station, about 15 km away from SGC053, so as to data in spring and winter. And the vertical crustal deformation is subsidence and the gravity change rate is about 1.79×10–8 (m·s–2)/a. The ratio of the changes in gravity and altitude related to the local vertical crustal movement is about –354×10–8 (m·s–2)/m.

Development of an instrument for diagnosing significant limitations in adaptive behavior in early childhood

Although adaptive behavior became a diagnostic criterion in the 5th edition of the American Association on Intellectual and Developmental Disabilities, AAIDD (Heber, 1959, 1961), there are no measures with adequate psychometric properties for diagnosing significant limitations in adaptive behavior according to the current conception of the construct. This fact has led to an excessive reliance on intellectual functioning measures. The goal of the present paper consists of presenting the development of the AAIDD's forthcoming Diagnostic Adaptive Behavior Scale (DABS) in Spain, and, specifically, it will be focused on one of its three forms: DABS Form 4-8 years old. The sample consisted of 388 people, aged 4-8 years old, with and without intellectual disabilities. The functioning of an initial pool of 168 items was analyzed under the assumptions of Item Response Theory models (IRT) with the aim to select those items around the cut-off point for determining significant limitations in adaptive behavior. A set of 72 items was selected (96 items were removed due to misfit, unsatisfying response category functioning, or low precision of measurement). The final version seems to be essentially unidimensional, shows good fit to the model, and represents an accurate precision of measurement around the cutoff point for diagnosing significant limitations in conceptual, social or practical skills.

P-496 - The hamilton depression rating scale cannot reliably measure mild or moderate depression

Introduction Demonstrating the superiority of antidepressants over placebo in randomized clinical trials of antidepressants (RCT-ADs) has been difficult. A recent meta-analysis of six RCT-ADs, by Fournier et al., concluded that the efficacy of antidepressants was “nonexistent to negligible” in mild and moderate depression. Objective and aim To reanalyze the same data in order to investigate if the meta-analysis was biased from insufficient measurement properties of the rating scale used, the 17-item Hamilton Depression Rating Scale (HDRS). Methods We got access to the primary data on item and individual level from 5 of the 6 meta-analyzed RCT-ADs. We reanalyzed these data by means of Item Response Theory (IRT). Results In each of the five studies the reliability of measurement was rapidly decreasing with diminishing depression severity. This resulted in low precision of measurement at endpoint levels and an underestimation of score reductions in patients who initially had milder depressions. As a consequence, 38% of the combined sample was measured at endpoint with IRT estimates of reliability that were less than half of the maximal. Conclusions The HDRS biases randomized clinical trials of antidepressants by providing unreliable primary data. Low or absent effect sizes are to be expected because of the scale's low precision and low sensitivity to change, particularly in mild and moderate depression. The conclusion of the Fournier et al. meta-analysis was therefore unfounded. The clinical value of antidepressants cannot be evaluated from unreliable data. Better measurement techniques for depression severity are urgently needed.

Hardware Design of Precision Injection Molding Machine Temperature Control Circuit

The existing hardware circuits can only measure a single point temperature in a small range owing to the influence of extremely little output voltage and the poor linear degrees of thermocouple on testing temperature ,and it is difficult to meet the demand of practical use because of its low measurement precision . This system realized accurate measurement of multipoint temperature in a large range using optimization design to overcome the above-mentioned defects,, It uses low maladjustment and high precision operation amplifier ADOP07 to constitute the inphase and shunt-wound difference amplification circuit to carry out non-electric measurement of thermocouple It also uses the CD4051 chip to compose the switch circuit at different time in order to realize the measurement of multi-thermocouple ,and the ICAD538 is used to implement square operation in order to make linear compensation of temperature , finally sends the measurement value to single-chip computer through A/D converter to process data which is controlled by the application of modern fuzzy controlling theory so as to reach the aim of precise measurement and control. The experiments show the system can realize accurate measurement of multipoint temperature in a wide from 20 to 400°C, and the experimental results are satisfying

CONTRAST AGENT IMAGING WITH AGENT SPECIFIC ULTRASOUND DETECTION

Highly specific measurements of flow in vessels, such as the coronary artery, can be obtained by processing cubic fundamental information. By showing flow in vessels with a high degree of contrast-to-tissue specificity, ultrasound based 3D contrast agent based coronary artery angiograms may be possible. Measurement and display of the velocity of agent from the cubic fundamental signal is provided simultaneously with display of cubic fundamental energy, such as providing a display map indexed by both energy and velocity. High pulse repetition frequency (PRF) for cubic fundamental detection in conjunction with long velocity measurement intervals may increase low velocity sensitivity and measurement precision. Pulsed wave (PW) Doppler may be improved by using a cubic fundamental sensitive pulse sequence. Using cubic fundamental sensitive techniques with other motion estimation techniques, such as two-dimensional velocity estimation or speckle tracking, may operate better than using other contrast agent detection techniques because of substantially reduced clutter.

Observation of superconducting gravimeter at Jiufeng seismic station

The relationship between the mass transfer beneath the earth surface and the vertical deformation could be studied using continuous relative gravimetry and continuous GPS observation.Compared to mobile relative gravimetry and absolute gravimetry,continuous relative gravimetry could be used to monitor the whole process of gravity changes and mass transfer,avoiding low measurement precision and temporal resolution.In this paper,more than 13000 hours gravity data recorded at Jiufeng seismic station using superconducting gravimetry(SGC053) are analyzed along with co-located absolute gravimetry data,air pressure,vertical displacement of surrounding GPS stations,WUHN IGS site and WHJF site,GRACE monthly time-variable gravity and two global continental water storage models(GLDAS,CPC).Gravity variations induced by solid earth tide,air pressure,pole tide and continental water loading are corrected using harmonic analysis method,atmospheric pressure admittance model,pole tide model and the correlation analysis with GRACE results and/or water storage models,then instrument drift is also corrected using co-located absolute gravity measurements.Based on the above processing,the relationship between the residual gravity time series and GPS vertical deformation is addressed.The harmonic analysis result for SGC053 gravity records,spanning about one and half years,shows that the white noise is about 1.14~1.40×10-8m·s-2 and the tidal factor errors of dominant tidal groups reach about 0.1‰.Compared to ocean tide loading(3×10-8m·s-2),the gravity due to air pressure(12×10-8m·s-2) and pole tide(10×10-8m·s-2) is much larger.The drift of SGC053,about 2.18×10-8(m·s-2)/a,is estimated using 4 absolute gravity co-located records of FG5-232.The result shows that the residual gravity caused by continental water loading in summer and autumn is about(6~8)×10-8m·s-2,by comparing residual gravity variations with both GARCE result and global continental water loading(GLDAS,CPC).Gravity variations corrected for water loading show perfect negative correlation with the vertical deformation of the GPS station,about 15km away from SGC053,so as to data in spring and winter.And the long-term vertical crustal deformation is subsidence and the gravity change rate is about 1.79×10-8(m·s-2)/a.The ratio of the changes in gravity and altitude related to the local vertical crustal movement is about-354×10-8(m·s-2)/m.

A Two-hierarchy Hough Transform Based Track Initiation Method for Sky-wave Over-the-Horizon Radar

The 3L (low data sampling rate, low measurement precision and low detection probability) features of sky-wave Over-The-Horizon Radar (OTHR) pose new challenges to the conventional track initiation methods. In this paper, a Two-Hierarchy Hough Transform track initiation method (TH-HT) is proposed. Firstly the range-time data space is used to hierarchical I Hough transform and rough candidate tracks are obtained, where Doppler is used as an accumulation constraint; then such rough candidate tracks are further refined by time-azimuth accumulation in hierarchical II Hough transform. Moreover, two theorems concerning the expectation of the number of clutters voting to each cell of each hierarchy are given, which provides a way of determining the two-hierarchy threshold value. In simulation, the proposed method is compared with the classical initiation method of OTHR-MMUPDA. Simulation results show that TH-HT has higher track detection probability and lower false track probability; meanwhile it is much less time-consuming.

Bayesian experimental design of tracer studies to monitor wastewater leakage from sewer networks

Despite more than a decade of research, the magnitude of wastewater leakage from defective sewer systems into groundwater supplies is still largely unknown, partly because reliable measurement methods are lacking. Although recently suggested in‐sewer tracer studies present a promising solution, it is unclear how to optimally design such studies in network settings. In this study we present a formal experimental design procedure, which uses Bayesian data analysis to improve the diagnosis of sewer leakage by combining tracer test data with prior knowledge on network topology and condition. From a simulation study, we show that (1) if a single sewer section is expected to have high leakage, that section should be distinguished in measurement layouts through isolated tests or appropriate overlapping of multiple tests; (2) if multiple sections are expected to have high leakage, layouts with tests that cover more than one high‐leakage section should be avoided; and (3) if a robust experimental design is desired, a balanced layout of tests that overlap multiple sections of high leakage, yet minimizes stretch length, should be chosen. This design will have the additional benefit of inducing covariance in the posterior distribution of exfiltration estimates, which can be used to advantage in subsequent studies. We apply these guidelines to a case study of a catchment in Zurich, Switzerland, and find that optimal layout design can improve the anticipated gain of information substantially relative to designs based on practical considerations alone. Remaining concerns regarding the procedure include (1) the generally poor understanding of the mechanisms governing sewer leakage, which can hamper reliable prior information on exfiltration; (2) the currently low measurement precision of sewer tracer studies, which might only allow for the detection of large leaks; and (3) the need for numerical implementation of the Bayesian inference procedure, which requires careful tuning and long computation times. In general, we were able to demonstrate that the incorporation of prior information through a Bayesian procedure adds significant value to experimental design, especially in situations with few “hard” data but good site‐specific knowledge, which is common in water resources research.

WEIS wheel speed real-time measuring method for VOSM

Wheel speed is one of the key parameters of vehicle operating attitude. To solve the problems in traditional wheel speed measuring methods, such as low measurement precision and the lack of real-time monitoring of the vehicle’s operating attitude, a wheel embedded intelligent sensors (WEIS) wheel speed measuring method for vehicle operating safety states monitoring (VOSM) is innovatively proposed. Radial acceleration signal is obtained through a WEIS module embedded in the hub. Using wavelet packet to implement wavelet de-noising for the non-stationary acceleration signals, and adopting short-time Fourier transform (STFT) algorithm to extract the signal characteristics, the wheel speed measurement can be achieved. The experimental result shows that under experimental conditions the speed measurement error is − 2.05%, and the speed measuring response time is 0.45 s.

Multidimensional Rasch Analysis of a Psychological Test With Multiple Subtests

Educational and psychological tests are often composed of multiple short subtests, each measuring a distinct latent trait. Unfortunately, short subtests suffer from low measurement precision, which makes the bandwidth—fidelity dilemma inevitable. In this study, the authors demonstrate how a multidimensional Rasch analysis can be employed to take into account the information about the correlation between latent traits such that the precision of each subtest measure can be improved and the correlation between latent traits can be accurately estimated. A real data set of the 13-scale Thinking Styles Inventory was analyzed with the traditional unidimensional approach and the multidimensional approach. The results demonstrate that in contrast to the unidimensional approach, the multidimensional approach yields a much higher level of measurement precision and a more appropriate estimate for the correlation between thinking styles. In conclusion, even short subtests can yield highly precise measures such that the bandwidth—fidelity dilemma is resolved.

Examination of the Item Structure of the Alberta Infant Motor Scale

The Alberta Infant Motor Scale (AIMS) is a screening tool for identifying delayed motor development from birth to 18 months of age. The purpose of this study was to examine the psychometric structure of the AIMS, including the hierarchical scale of items and the precision for measuring infant ability at different ages. Ninety-seven infants with varying degrees of risk of developmental disability were recruited from three hospitals or from the community in the Chicago metropolitan area. Infants were tested on the AIMS at three, six, nine, and 12 months of age. The hierarchical structure and the range and distribution of item difficulty on the AIMS were analyzed using Rasch psychometric analysis. The Rasch analysis confirmed that items for each of the four testing positions (supine, prone, sitting, and standing) were arranged in increasing order of difficulty, but a ceiling effect was present. Gaps exist at six ability levels, indicating low precision of measurement for differentiating among infants after about nine months of age. The AIMS shows a ceiling effect, measures infant ability best from three to nine months of age, and has few items available for discriminating among infants after they pass the controlled lowering through standing item. Clinical impressions should be drawn with caution at ages when the precision of measurement is low.

An examination of the psychometric properties of the physical self-description questionnaire using a polytomous item response model

Abstract Objectives : This study proposes polytomous item response theory (IRT) as a method for item analysis of Likert-type responses that are commonly used in sport and exercise psychology measures. Thus, the aims of this study were to determine the psychometric qualities of the items at the endorsement option, item and test level. Method : The graded response IRT model ( Samejima, Psychometrika Monograph 17 (1969) ) was fitted to the 70-item Physical Self-Description Questionnaire (PSDQ) ( Marsh et al., J Sport Exer Psychol 15 (1994) 270), which was administered to a large sample of Australian adolescents enrolled in a metropolitan sports high school. Results : By analyzing in greater detail the psychometric properties of items, the results show how polytomous IRT can provide new insight into item analysis that is not available in traditional classical test analyses. The graded response IRT model ( Samejima, Psychometrika Monograph 17 (1969) ) allowed for the identification of items that provided high and low measurement precision, items that needed rewording, and items that are redundant in that they add little information or had redundant response options. Conclusion : The PSDQ was most discriminating among participants with lower estimates of physical self-concept. Furthermore, the study showed how choosing items to maximize reliability may not always be the optimal strategy. IRT models provide item/sample free calibration, local standard errors, and give more information at the item level by offering additional insights as to qualities of the items over and above those gleaned from the classical test theory models (CTT). The increased information at each Likert-scale point, and the added information from the polytomous IRT model, make this an attractive approach for the development of psychological measures using a polytomously scored item format.

Influence of precision, sample size and design on the beta error of linearity tests

The beta error of two linearity tests for the detection of lack-of-fit to a straight line calibration model based on small sample size (6≤n≤10) has been evaluated namely, the ANOVA lack-of-fit to the first degree model and the test of significance of b2, the second degree coefficient from the second degree model fitted through the data. For these investigations different models, designs and measurement precisions were considered by means of simulations. The effect of heteroscedasticity was also evaluated. The results obtained indicated that the test of significance of b2 in general performs better than the ANOVA test. The designs with three concentration levels (measurements positioned at both extremes and at concentration in the middle of the calibration range) give the best results. Heteroscedasticity and low measurement precision increase the probability that lack-of-fit is not detected. Two means to predict the beta error for the test of significance of b2 are proposed: (i) prediction derived from the plots of the beta error versus the ratio of the deviation from linearity (expressed as the average relative prediction error) to the measurement precision (expressed as %RSD at the concentration in the middle of the calibration range) and (ii) prediction using the formula. The formula to determine the sample size that allows the detection of a certain deviation from linearity with a specified beta error is also given.

The permicron; a unit of wave number.

IN spite of the great theoretical advantages of recording spectra in terms of frequency or wave number, most data on visible and ultra-violet spectra, more particularly spectra of solutions, are in practice expressed as wave-lengths with the millimicron as a favourite unit. One reason for this preference, apart from habit, is found in the inconvenience of sec.−1 and cm.−1 as units. Frequencies expressed in sec.−1 involve large powers of ten (∼ 1015), while the fresnel1 (= 1012 sec.−1) has never become popular. Wave numbers in cm.−1 are of the order of 104, and require the use of written or spoken powers of ten if the recorded values are to express the relatively low precision of measurement in spectra of solution. Thus, to say that the absorption maximum of bromine is at 405 mµ. implies a reasonable uncertainty of about 10 A. in locating it. To express the value as 24,691 cm.−1 or even as 24,700 cm.−1 implies a much greater precision than is obtainable experimentally.