Science.gov

Sample records for accelerometer cut points

  1. Accelerometer Cut-Points and Youth Physical Activity Prevalence

    ERIC Educational Resources Information Center

    Mota, Jorge; Valente, Monica; Aires, Luisa; Silva, Pedro; Santos, Maria Paula; Ribeiro, Jose Carlos

    2007-01-01

    The purpose of this study was twofold: first, to examine the effects of specific cut-off scoring points (on the estimated prevalence of meeting health-related guidelines for physical activity in youth) and, second, to document the differences in gender physical activity patterns according to two different cut-off points. The sample comprised 62…

  2. Cross-validation of Waist-Worn GENEA Accelerometer Cut-Points

    PubMed Central

    Welch, Whitney A.; Bassett, David R.; Freedson, Patty S.; John, Dinesh; Steeves, Jeremy A.; Conger, Scott A.; Ceaser, Tyrone G.; Howe, Cheryl A.; Sasaki, Jeffer E.

    2014-01-01

    Purpose The purpose of this study was to determine the classification accuracy of the waist GENEA cut-points developed by Esliger et al. for predicting intensity categories across a range of lifestyle activities. Methods Each participant performed one of two routines, consisting of seven lifestyle activities (home/office, ambulatory, and sport). The GENEA was worn on the right waist and oxygen uptake was continuously measured using the Oxycon mobile. A one-way chi-square was used to determine the classification accuracy of the GENEA cut-points. Cross tabulation tables provided information on under- and over-estimations, and sensitivity and specificity analyses of the waist cut-points were also performed. Results Spearman’s rank order correlation for the GENEA SVMgs and Oxycon mobile MET values was 0.73. For all activities combined, the GENEA accurately predicted intensity classification 55.3% of the time, and increased to 58.3% when stationary cycling was removed from the analysis. The sensitivity of the cut-points for the four intensity categories ranged from 0.244 to 0.958 and the specificity ranged from 0.576 to 0.943. Conclusion In this cross-validation study, the proposed GENEA cut-points had a low overall accuracy rate for classifying intensity (55.3%) when engaging in 14 different lifestyle activities. PMID:24496118

  3. Effect of Accelerometer Cut-Off Points on the Recommended Level of Physical Activity for Obesity Prevention in Children

    PubMed Central

    Dygrýn, Jan; Mitáš, Josef; Jakubec, Lukáš; Frömel, Karel

    2016-01-01

    There is no general consensus regarding which accelerometer cut-off point (CoP) is most acceptable to estimate the time spent in moderate-to-vigorous physical activity (MVPA) in children and choice of an appropriate CoP primarily remains a subjective decision. Therefore, this study aimed to analyze the influence of CoP selection on the mean MVPA and to define the optimal thresholds of MVPA derived from different accelerometer CoPs to avoid overweight/obesity and adiposity in children aged 7 to 12 years. Three hundred six children participated. Physical activity (PA) was monitored for seven consecutive days using an ActiGraph accelerometer (model GT3X) and the intensity of PA was estimated using the five most frequently published CoPs. Body adiposity was assessed using a multi-frequency bioelectrical impedance analysis. There was found a wide range of mean levels of MVPA that ranged from 27 (Puyau CoP) to 231 min∙d–1 (Freedson 2005 CoP). A receiver operating characteristic curve analysis indicated that the optimal thresholds for counts per minute (cpm) and MVPA derived from the Puyau CoP was the most useful in classifying children according to their body mass index (BMI) and fat mass percentage (FM%). In the total sample, the optimal thresholds of the MVPA derived from the Puyau CoP were 22 and 23 min∙d–1 when the categories based on BMI and FM%, respectively, were used. The children who did not meet these optimal thresholds had a significantly increased risk of being overweight/obese (OR = 2.88, P < 0.01) and risk of having excess fat mass (OR = 2.41, P < 0.01). In conclusion, the decision of selecting among various CoPs significantly influences the optimal levels of MVPA. The Puyau CoP of 3 200 cmp seems to be the most useful for defining the optimal level of PA for pediatric obesity prevention. PMID:27723835

  4. Validation of the Phillips et al. GENEActiv accelerometer wrist cut-points in children aged 5-8 years old.

    PubMed

    Duncan, Michael J; Wilson, Susie; Tallis, Jason; Eyre, Emma

    2016-12-01

    This study examined the accuracy of the Phillips et al. GENEActiv accelerometer wrist worn cut-points in children aged 5-8. Fifteen children (six girls, nine boys) aged 5-8 years wore a GENEActiv monitor on their non-dominant wrist while undertaking 5 min bouts of lying supine, playing Lego, walking at slow, medium and fast pace and running. Receiver operating curve (ROC) analysis was employed to establish how well the Phillips et al. (2013) cut-points classified intensity of the activities compared to the actual intensity determined by indirect calorimetry. Area under the curve (AUC) values were high for sedentary (.970), moderate (.815) and vigorous (.974) activity.

  5. The Relationship of Actigraph Accelerometer Cut-Points for Estimating Physical Activity with Selected Health Outcomes: Results from NHANES 2003-06

    ERIC Educational Resources Information Center

    Loprinzi, Paul D.; Lee, Hyo; Cardinal, Bradley J.; Crespo, Carlos J.; Andersen, Ross E.; Smit, Ellen

    2012-01-01

    The purpose of this study was to examine the influence of child and adult cut-points on physical activity (PA) intensity, the prevalence of meeting PA guidelines, and association with selected health outcomes. Participants (6,578 adults greater than or equal to 18 years, and 3,174 children and adolescents less than or equal to 17 years) from the…

  6. Single point optical calibration of accelerometers at NIST

    NASA Astrophysics Data System (ADS)

    Payne, Bev

    2006-06-01

    Typical accelerometer calibrations by laser interferometer are performed by measuring displacement at three places on the shaker table. Each of these measurements, made along the perimeter of the accelerometer, requires repositioning and realigning of the interferometer. This is done to approximate the actual displacement of the accelerometer. Using a dual-coil shaker with a small moving element and two coaxially-located and rigidly-attached mounting tables allows placing the accelerometer on one table and measuring displacement directly on the center axis of the second table. This was found to work effectively at lower frequencies, up to about 5 kHz, with mounting tables of conventional materials such as stainless steel. However, for higher frequencies the use of steel results in unwanted relative motion between the two mounting tables. Mounting tables of beryllium with nickel coating have been used at NIST to overcome this difficulty. This paper shows the calibration results of single point, on-axis measurements, using fringe counting and sine-approximation methods. The results compare favorably with three point measurements made by fringe disappearance using a conventional piezo-electric shaker at frequencies up to 15 kHz.

  7. ACCELEROMETER

    DOEpatents

    Pope, K.E.

    1958-11-25

    A device, commonly known as an accelerometer, is described which may be utllized for measuring acceleratlon with high sensitivity and accuracy tbroughout a relatively wlde range of values. In general, the accelerometer consists of an assembly, including an electric motor stator and a mass element located away from the axis of rotation of the stator, rotatably mounted on a support, and an electric motor rotor positioned within the stator and rotatable thereln. An electrlcal switching circuit controlled by the movement of the stator lntermittently energizes the rotor winding and retards move ment of the stator, and a centrifugal switch is rotatable with the rotor to operate upon attainment of a predetermined rotor rotational velocity.

  8. Establishing school day pedometer step count cut-points using ROC curves in low-income children.

    PubMed

    Burns, Ryan D; Brusseau, Timothy A; Fu, You; Hannon, James C

    2016-05-01

    Previous research has not established pedometer step count cut-points that discriminate children that meet school day physical activity recommendations using a tri-axial ActiGraph accelerometer criterion. The purpose of this study was to determine step count cut-points that associate with 30min of school day moderate-to-vigorous physical activity (MVPA) in school-aged children. Participants included 1053 school-aged children (mean age=8.4±1.8years) recruited from three low-income schools from the state of Utah in the U.S. Physical activity was assessed using Yamax DigiWalker CW600 pedometers and ActiGraph wGT3X-BT triaxial accelerometers that were concurrently worn during school hours. Data were collected at each school during the 2014-2015 school year. Receiver operating characteristic (ROC) curves were used to determine pedometer step count cut-points that associated with at least 30min of MVPA during school hours. Cut-points were determined using the maximum Youden's J statistic (J max). For the total sample, the area-under-the-curve (AUC) was 0.77 (p<0.001) with a pedometer cut-point of 5505 steps (J max=0.46, Sensitivity=63%, Specificity=84%; Accuracy=76%). Step counts showed greater diagnostic ability in girls (AUC=0.81, p<0.001; Cut-point=5306 steps; Accuracy=78.8%) compared to boys (AUC=0.72, p<0.01; Cut-point=5786 steps; Accuracy=71.4%). Pedometer step counts showed good diagnostic ability in girls and fair diagnostic ability in boys for discriminating children that met at least 30min of MVPA during school hours.

  9. Statistical considerations for calculation of immunogenicity screening assay cut points.

    PubMed

    Hoffman, David; Berger, Marion

    2011-10-28

    Most therapeutic proteins induce an unwanted immune response. Antibodies elicited by these therapeutic proteins may significantly alter drug safety and efficacy, highlighting the need for the strategic assessment of immunogenicity at various stages of clinical development. Immunogenicity testing is generally conducted by a multi-tiered approach whereby patient samples are initially screened for the presence of anti-drug antibodies in a screening assay. The screening assay cut point is statistically determined by evaluation of drug-naïve samples and is typically chosen to correspond to a false positive rate of 5%. While various statistical approaches for determination of this screening cut point have been commonly adopted and described in the immunogenicity literature, the performance of these approaches has not been fully evaluated. This paper reviews various statistical approaches for cut point calculation, evaluates the impact of sampling design and variability on the performance of each statistical approach, and highlights the difference between an 'average' or 'confidence-level' cut point in order to develop more specific recommendations regarding the statistical calculation of immunogenicity screening cut points.

  10. 10. CANAL CUT THROUGH SHALE BEDROCK ON PROMINENT POINT, LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. CANAL CUT THROUGH SHALE BEDROCK ON PROMINENT POINT, LOOKING NORTH-NORTHEAST. NOTE CONCRETE ABUTMENTS PROBABLY INSTALLED IN 1935 TO PREVENT WATER FROM ESCAPING THROUGH A CANAL BANK BREACH. - Snake River Ditch, Headgate on north bank of Snake River, Dillon, Summit County, CO

  11. [Studies on the cutting ability of dental diamond points--the trial manufacture of the cutting test apparatus (author's transl)].

    PubMed

    Miyairi, H; Nagai, M; Muramatsu, A

    1978-10-01

    Diamond points and tungstencarbite burs are used as the dental cutting tools for many appliance accordingly with the many purpose of used positions. Notwithstanding that the dental cutting tools have been usually applied for many purpose of dental treatment, the paper on these studies have scarcely been reported. In this studies the test of dental cutting tools curried out using the diamond points and examined these characteristics. As the problems on the cutting tests are the push load of cutting tools and the cutting quantities. This studies tried to make the test apparatus for the cutting test of dental diamond points considering to dental treatments. The glass plates used for photograph are used for cutting materials supposing to the enamel properties of teeth and the cutting tests put into practice for the types of diamond points with different diameter. The cutting characteristics of the diamond points are examined with the using of the test results and are appreciated with the considering to the test apparatus.

  12. Combined influence of epoch length, cut-point and bout duration on accelerometry-derived physical activity

    PubMed Central

    2014-01-01

    Background It is difficult to compare accelerometer-derived estimates of moderate-to-vigorous physical activity (MVPA) between studies due to differences in data processing procedures. We aimed to evaluate the effects of accelerometer processing options on total and bout-accumulated time spent in MVPA in adults. Methods 267 participants from the ProActive Trial provided 1236 days of valid physical activity (PA) data, collected using a 5-s epoch with ActiGraph GT1M accelerometers. We integrated data over 5-s to 60-s epoch lengths (EL) and applied two-level mixed effects regression models to MVPA time, defined using 1500 to 2500 counts/minute (cpm) cut-points (CP) and bout durations (BD) from 1 to 15 min. Results Total MVPA time was lower on longer EL and higher CP (47 vs 26 min/day and 26 vs 5 min/day on 1500 vs 2500 cpm on 5-s and 60-s epoch, respectively); this could be approximated as MVPA = exp[2.197 + 0.279*log(CP) + 6.120*log(EL) - 0.869*log(CP)*log(EL)] with an 800 min/day wear-time. In contrast, EL was positively associated with time spent in bout-accumulated MVPA; the approximating equation being MVPA = exp[54.679 - 6.268*log(CP) + 6.387*log(EL) - 10.000*log(BD) - 0.162*log(EL)*log(BD) - 0.626*log(CP)*log(EL) + 1.033*log(CP)*log(BD)]. BD and CP were inversely associated with MVPA, with higher values attenuating the influence of EL. Conclusions EL, CP and BD interact to influence estimates of accelerometer-determined MVPA. In general, higher CP and longer BD result in lower MVPA but the direction of association for EL depends on BD. Reporting scaling coefficients for these key parameters across their frequently used ranges would facilitate comparisons of population-level accelerometry estimates of MVPA. PMID:24612726

  13. Effect of cut-off points on performance of laser fluorescence for detecting occlusal caries.

    PubMed

    Braga, Mariana M; Mendes, Fausto M; Imparato, José Carlos P; Rodrigues, Célia R M D

    2007-01-01

    This in vitro study aimed to evaluate the influence of cut-off points on the performance of laser fluorescence (LF) in detecting occlusal caries in permanent and primary teeth. The use of different cut-off points influenced the performance of LF device in detection of occlusal caries in both kind of teeth, but the performance in permanent teeth suffered more influence from variation of cut-off points scales than in primary group.

  14. Sedentary Behaviour Profiling of Office Workers: A Sensitivity Analysis of Sedentary Cut-Points.

    PubMed

    Boerema, Simone T; Essink, Gerard B; Tönis, Thijs M; van Velsen, Lex; Hermens, Hermie J

    2015-12-25

    Measuring sedentary behaviour and physical activity with wearable sensors provides detailed information on activity patterns and can serve health interventions. At the basis of activity analysis stands the ability to distinguish sedentary from active time. As there is no consensus regarding the optimal cut-point for classifying sedentary behaviour, we studied the consequences of using different cut-points for this type of analysis. We conducted a battery of sitting and walking activities with 14 office workers, wearing the Promove 3D activity sensor to determine the optimal cut-point (in counts per minute (m·s(-2))) for classifying sedentary behaviour. Then, 27 office workers wore the sensor for five days. We evaluated the sensitivity of five sedentary pattern measures for various sedentary cut-points and found an optimal cut-point for sedentary behaviour of 1660 × 10(-3) m·s(-2). Total sedentary time was not sensitive to cut-point changes within ±10% of this optimal cut-point; other sedentary pattern measures were not sensitive to changes within the ±20% interval. The results from studies analyzing sedentary patterns, using different cut-points, can be compared within these boundaries. Furthermore, commercial, hip-worn activity trackers can implement feedback and interventions on sedentary behaviour patterns, using these cut-points.

  15. Determining BMI cut points based on excess percent body fat in US children and adolescents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current cut points for overweight were derived statistically from BMI distribution. The study aimed at determining age-, gender-, and ethnic-specific BMI cut points based on excess body fat in US children and adolescents aged 8-17 years, who participated in the National Health and Nutrition Examinat...

  16. Prevalence of energy intake misreporting in Malay children varies based on application of different cut points.

    PubMed

    Yang, Wai Yew; Burrows, Tracy; Collins, Clare E; MacDonald-Wicks, Lesley; Williams, Lauren T; Chee, Winnie Siew Swee

    2014-12-01

    This study aimed to identify the prevalence of energy misreporting amongst a sample of Malay children aged 9-11 years (n = 14) using a range of commonly used cut points. Participants were interviewed using repeated 24 h dietary recalls over three occasions. The Goldberg equations (1991 and 2000), Torun cut points and the Black and Cole method were applied to the data. Up to 11 of 14 children were classified as misreporters, with more under-reporters (between seven and eight children) than over-reporters (four or less children). There were significant differences in the proportion of children classified as energy misreporters when applying basal metabolic rate calculated using FAO/UNU/WHO (1985) and Malaysian-specific equations (p < 0.05). The results show that energy misreporting is common amongst Malay children, varying according to cut point chosen. Objective evaluation of total energy expenditure would help identify which cut point is appropriate for use in Malay paediatric populations.

  17. Classification accuracy of the wrist-worn GENEA accelerometer

    PubMed Central

    Welch, Whitney A.; Bassett, David R.; Thompson, Dixie L.; Freedson, Patty S.; Staudenmayer, John W.; John, Dinesh; Steeves, Jeremy A.; Conger, Scott A.; Ceaser, Tyrone; Howe, Cheryl A.; Sasaki, Jeffer E.; Fitzhugh, Eugene C.

    2013-01-01

    Purpose The purpose of this study was to determine whether the published left-wrist cut-points for the triaxial GENEA accelerometer, are accurate for predicting intensity categories during structured activity bouts. Methods A convenience sample of 130 adults wore a GENEA accelerometer on their left wrist while performing 14 different lifestyle activities. During each activity, oxygen consumption was continuously measured using the Oxycon mobile. Statistical analysis used Spearman's rank correlations to determine the relationship between measured and estimated intensity classifications. Cross tabulation tables were constructed to show under- or over-estimation of misclassified intensities. One-way chi-square tests were used to determine whether the intensity classification accuracy for each activity differed from 80%. Results For all activities the GENEA accelerometer-based physical activity monitor explained 41.1% of the variance in energy expenditure. The intensity classification accuracy was 69.8% for sedentary activities, 44.9% for light activities, 46.2% for moderate activities, and 77.7% for vigorous activities. The GENEA correctly classified intensity for 52.9% of observations when all activities were examined; this increased to 61.5% with stationary cycling removed. Conclusion A wrist-worn triaxial accelerometer has modest intensity classification accuracy across a broad range of activities, when using the cut-points of Esliger et al. Although the sensitivity and specificity are less than those reported by Esliger et al., they are generally in the same range as those reported for waist-worn, uniaxial accelerometer cut-points. PMID:23584403

  18. A Distance-Weighted Graph-Cut Method for the Segmentation of Laser Point Clouds

    NASA Astrophysics Data System (ADS)

    Dutta, A.; Engels, J.; Hahn, M.

    2014-08-01

    Normalized Cut according to (Shi and Malik 2000) is a well-established divisive image segmentation method. Here we use Normalized Cut for the segmentation of laser point clouds in urban areas. In particular we propose an edge weight measure which takes local plane parameters, RGB values and eigenvalues of the covariance matrices of the local point distribution into account. Due to its target function, Normalized Cut favours cuts with "small cut lines/surfaces", which appears to be a drawback for our application. We therefore modify the target function, weighting the similarity measures with distant-depending weights. We call the induced minimization problem "Distance-weighted Cut" (DWCut). The new target function leads to a slightly more complicated generalized eigenvalue problem than in case of the Normalized Cut; on the other hand, the new target function is easier to interpret and avoids the just-mentioned drawback. DWCut can be beneficially combined with an aggregation in order to reduce the computational effort and to avoid shortcomings due to insufficient plane parameters. Finally we present examples for the successful application of the Distance-weighted Cut principle. The method was implemented as a plugin into the free and open source geographic information system SAGA; for preprocessing steps the proprietary SAGA-based LiDAR software LIS was applied.

  19. Accelerometer design

    NASA Technical Reports Server (NTRS)

    Norton, F H; Warner, Edward P

    1921-01-01

    In connection with the development of an accelerometer for measuring the loads on airplanes in free flight a study of the theory of such instruments has been made, and the results of this study are summarized in this report. A portion of the analysis deals particularly with the sources of error and with the limitations placed on the location of the instrument in the airplane. The discussion of the dynamics of the accelerometer includes a study of its theoretical motions and of the way in which they are affected by the natural period of vibration and by the damping, together with a report of some experiments on the effect of forced vibrations on the record.

  20. Computation of the spectral density of two-point functions: Complex masses, cut rules, and beyond

    SciTech Connect

    Dudal, David; Guimaraes, Marcelo S.

    2011-02-15

    We present a steepest descent calculation of the Kaellen-Lehmann spectral density of two-point functions involving complex conjugate masses in Euclidean space. This problem occurs in studies of (gauge) theories with Gribov-like propagators. As the presence of complex masses and the use of Euclidean space brings the theory outside of the strict validity of the Cutkosky cut rules, we discuss an alternative method based on the Widder inversion operator of the Stieltjes transformation. It turns out that the results coincide with those obtained by naively applying the cut rules. We also point out the potential usefulness of the Stieltjes (inversion) formalism when nonstandard propagators are used, in which case cut rules are not available at all.

  1. Effects of cyclone diameter on performance of 1D3D cyclones: Cut point and slope

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyclones are a commonly used air pollution abatement device for separating particulate matter (PM) from air streams in industrial processes. Several mathematical models have been proposed to predict the cut point of cyclones as cyclone diameter varies. The objective of this research was to determine...

  2. Wall sticking of high water-cut crude oil transported at temperatures below the gel point

    NASA Astrophysics Data System (ADS)

    Zheng, Haimin; Huang, Qiyu; Wang, Changhui

    2015-12-01

    Some high water-cut crude oils can flow in the temperature below the oil gel point, while oil particles may adhere to the pipe wall as paste; this process is known as ‘wall sticking’. This can cause partial or even total blocking of the transportation pipe. Several experiments using a laboratory flow loop were conducted to study the wall sticking characteristics of high water-cut crude oils. The experimental results indicated that the predominant influencing factors of wall sticking included shear stress, water-cut and differences between gel point and wall temperature. The wall sticking rate and occurrence temperature decrease with the increase of water-cut and shear stress. The criterion for the wall sticking occurrence temperature (WSOT), and the regression formula of the wall sticking thickness for high water-cut crude oil were then established. Typical case studies indicated that the prediction results obtained from the WSOT criterion and the wall sticking thickness regression formula were in accordance with the measured values. The wall sticking rate and WSOT vary widely under different conditions and it is necessary to consider its non-uniformity in production.

  3. Enhancing efficiency and quality of statistical estimation of immunogenicity assay cut points through standardization and automation.

    PubMed

    Su, Cheng; Zhou, Lei; Hu, Zheng; Weng, Winnie; Subramani, Jayanthi; Tadkod, Vineet; Hamilton, Kortney; Bautista, Ami; Wu, Yu; Chirmule, Narendra; Zhong, Zhandong Don

    2015-10-01

    Biotherapeutics can elicit immune responses, which can alter the exposure, safety, and efficacy of the therapeutics. A well-designed and robust bioanalytical method is critical for the detection and characterization of relevant anti-drug antibody (ADA) and the success of an immunogenicity study. As a fundamental criterion in immunogenicity testing, assay cut points need to be statistically established with a risk-based approach to reduce subjectivity. This manuscript describes the development of a validated, web-based, multi-tier customized assay statistical tool (CAST) for assessing cut points of ADA assays. The tool provides an intuitive web interface that allows users to import experimental data generated from a standardized experimental design, select the assay factors, run the standardized analysis algorithms, and generate tables, figures, and listings (TFL). It allows bioanalytical scientists to perform complex statistical analysis at a click of the button to produce reliable assay parameters in support of immunogenicity studies.

  4. Exact confidence interval estimation for the Youden index and its corresponding optimal cut-point.

    PubMed

    Lai, Chin-Ying; Tian, Lili; Schisterman, Enrique F

    2012-05-01

    In diagnostic studies, the receiver operating characteristic (ROC) curve and the area under the ROC curve are important tools in assessing the utility of biomarkers in discriminating between non-diseased and diseased populations. For classifying a patient into the non-diseased or diseased group, an optimal cut-point of a continuous biomarker is desirable. Youden's index (J), defined as the maximum vertical distance between the ROC curve and the diagonal line, serves as another global measure of overall diagnostic accuracy and can be used in choosing an optimal cut-point. The proposed approach is to make use of a generalized approach to estimate the confidence intervals of the Youden index and its corresponding optimal cut-point. Simulation results are provided for comparing the coverage probabilities of the confidence intervals based on the proposed method with those based on the large sample method and the parametric bootstrap method. Finally, the proposed method is illustrated via an application to a data set from a study on Duchenne muscular dystrophy (DMD).

  5. Detection of fallen trees in ALS point clouds using a Normalized Cut approach trained by simulation

    NASA Astrophysics Data System (ADS)

    Polewski, Przemyslaw; Yao, Wei; Heurich, Marco; Krzystek, Peter; Stilla, Uwe

    2015-07-01

    Downed dead wood is regarded as an important part of forest ecosystems from an ecological perspective, which drives the need for investigating its spatial distribution. Based on several studies, Airborne Laser Scanning (ALS) has proven to be a valuable remote sensing technique for obtaining such information. This paper describes a unified approach to the detection of fallen trees from ALS point clouds based on merging short segments into whole stems using the Normalized Cut algorithm. We introduce a new method of defining the segment similarity function for the clustering procedure, where the attribute weights are learned from labeled data. Based on a relationship between Normalized Cut's similarity function and a class of regression models, we show how to learn the similarity function by training a classifier. Furthermore, we propose using an appearance-based stopping criterion for the graph cut algorithm as an alternative to the standard Normalized Cut threshold approach. We set up a virtual fallen tree generation scheme to simulate complex forest scenarios with multiple overlapping fallen stems. This simulated data is then used as a basis to learn both the similarity function and the stopping criterion for Normalized Cut. We evaluate our approach on 5 plots from the strictly protected mixed mountain forest within the Bavarian Forest National Park using reference data obtained via a manual field inventory. The experimental results show that our method is able to detect up to 90% of fallen stems in plots having 30-40% overstory cover with a correctness exceeding 80%, even in quite complex forest scenes. Moreover, the performance for feature weights trained on simulated data is competitive with the case when the weights are calculated using a grid search on the test data, which indicates that the learned similarity function and stopping criterion can generalize well on new plots.

  6. Validity of wrist worn accelerometers and comparability between hip and wrist placement sites in estimating physical activity behaviour in preschool children.

    PubMed

    Hislop, Jane; Palmer, Nicole; Anand, Priya; Aldin, Tara

    2016-09-21

    Wrist-worn accelerometers can increase compliance with wearing accelerometers, however, several large scale studies continue to use hip-worn accelerometers and it is unclear how comparable data is from the two sites. The study aims were: to investigate agreement between wrist- and hip- worn accelerometers and to determine the validity of Johansson et al cut-points for wrist worn accelerometers in preschool children. A sample of 32 preschool children (21 boys, 4.2 (0.5) years, BMI 16.6 (1.1)) were videoed wearing GT3X+  accelerometers on their wrist and hip while they engaged in 1 h of free-play in their nursery. Children's activity were coded using, the children's activity rating scale (CARS): with CARS, level 1 'sedentary' and levels 2-5 were classified as time spent in total physical activity (TPA). Accelerometry data were processed using Johansson et al cut-points for the wrist data and Evenson et al cut-points for the hip data, into time spent in different intensities of physical activity (PA). The mean counts per minute (cpm) from the hip and wrist were compared. There was a strong correlation between the hip and wrist cpm (r  =  0.81, p  <  0.01) and total count data (r  =  0.83 p  <  0.01), however there was a large systematic bias with wide limits of agreement. Good agreement (mean difference (LOA) 1.1 (-9.9, 12.1) was found between the CARS estimate of TPA (29.5 (10.4) mins) and the wrist estimate, using the Johansson et al cut points (28.4 (9.8) mins). There was also a reasonable agreement between the hip estimates with the Evenson et al cut-points and Johansson et al estimate (mean difference (LOA):6.3 (-8.8, 21.4) mins. In conclusion, the findings suggest that the Johansson et al (2013 Pediatr. Obes. 10 1-6) cut-points applied to wrist worn accelerometers provides a valid estimate of TPA in preschool children and have reasonable agreement with Evenson et al cut-points applied to hip accelerometers.

  7. Defining a BMI Cut-Off Point for the Iranian Population: The Shiraz Heart Study

    PubMed Central

    Babai, Mohammad Ali; Arasteh, Peyman; Hadibarhaghtalab, Maryam; Naghizadeh, Mohammad Mehdi; Salehi, Alireza; Askari, Alireza; Homayounfar, Reza

    2016-01-01

    In this study we evaluated and redefined the optimum body mass index (BMI) cut-off point for the Iranian population based on metabolic syndrome (MeS) risk factors. We further evaluated BMI cut-off points with and without waist circumference (WC) as a cofactor of risk and compared the differences. This study is part of the largest surveillance programs conducted in Shiraz, Iran, termed the Shiraz Heart study. Our study sample included subjects between the ages of 20 to 65 years old. After excluding pregnant women, those with missing data and those with comorbid disease, a total of 12283 made up the study population. The participants underwent a series of tests and evaluations by trained professionals in accordance with WHO recommendations. Hypertension, abnormal fasting blood sugar (FBS), triglyceride (TG) and high density lipoprotein cholesterol (HDL) (in the context of the definition of metabolic syndrome) were prevalent among 32.4%, 27.6%, 42.1 and 44.2% of our participants, respectively. Women displayed higher rates of overall obesity compared to men (based on the definition by the WHO as higher than 30 kg/m2). Regarding MeS, 38.9% of our population had the all symptoms of MeS which was more prevalent among women (41.5% vs. 36%). When excluding WC in the definition of MeS, results showed that males tend to show a higher rate of metabolic risk factors (19.2% vs. 15.6%). Results of multivariate analysis showed that parallel to an increase in BMI, the odds ratio (OR) for acquiring each component of the metabolic syndrome increased (OR = 1.178; CI: 1.166–1.190). By excluding WC, the previous OR decreased (OR = 1.105; CI: 1.093–1.118). Receiver Operating Characteristic (ROC) curve analysis showed that the optimum BMI cut-off point for predicting metabolic syndrome was 26.1 kg/m2 and 26.2 kg/m2 [Accuracy (Acc) = 69% and 61%, respectively)] for males and females, respectively. The overall BMI cut-off for both sexes was 26.2 kg/m2 (Acc = 65%) with sensitivity and

  8. Space vehicle accelerometer applications

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The physics of accelerometer applications are reviewed, and details are given on accelerometer instruments and the principles of their operations. The functions to which accelerometers are applied are listed, and terms commonly used in accelerometer reports are defined. Criteria guides state what rule, limitation, or standard must be imposed on each essential design element to insure successful design. Elaboration of these criteria in the form of recommended practices show how to satisfy each of these criteria, with the best procedure described when possible.

  9. A review of the cut-off points for the diagnosis of vitamin B12 deficiency in the general population.

    PubMed

    Aparicio-Ugarriza, Raquel; Palacios, Gonzalo; Alder, Monika; González-Gross, Marcela

    2015-07-01

    Vitamin B12 deficit is one of the most common vitamin deficiencies. However, there is no consensus on the cut-off points for vitamin B12 and its co-markers, such as folate, holotranscobalamin, methylmalonic acid and homocysteine. In order to establish the state of the art about cut-off points used to determine vitamin B12 deficiency in the last decades, the database MEDLINE was used for searching studies published in adults between December 1992 and May 2014 (69 articles), using search terms like 'vitamin B12', 'cobalamin', 'cut-off', 'deficiency' alone or in combinations. Broad ranges of cut-off points for vitamin B12 and its biomarkers were identified: vitamin B12 ranged between 100 pmol/L and 350 pmol/L, holotranscobalamin 20-50 pmol/L, methylmalonic acid 0.210-0.470 μmol/L, homocysteine 10-21.6 μmol/L, serum folate 3.7-15.9 nmol/L and red blood cell 124-397 nmol/L. For the majority of studies, the potential influence of age, analytical methods, gender and fortified food consumption was not taken in account when choosing cut-off values. This could explain the discrepancies between studies on vitamin B12 and folate deficiency prevalences. We conclude that there is inconsistency in the literature regarding vitamin B12 cut-offs. It would be necessary to establish different reference cut-offs according to age, considering the analytical methods used.

  10. Probability distribution of the entanglement across a cut at an infinite-randomness fixed point

    NASA Astrophysics Data System (ADS)

    Devakul, Trithep; Majumdar, Satya N.; Huse, David A.

    2017-03-01

    We calculate the probability distribution of entanglement entropy S across a cut of a finite one-dimensional spin chain of length L at an infinite-randomness fixed point using Fisher's strong randomness renormalization group (RG). Using the random transverse-field Ising model as an example, the distribution is shown to take the form p (S |L ) ˜L-ψ (k ) , where k ≡S /ln[L /L0] , the large deviation function ψ (k ) is found explicitly, and L0 is a nonuniversal microscopic length. We discuss the implications of such a distribution on numerical techniques that rely on entanglement, such as matrix-product-state-based techniques. Our results are verified with numerical RG simulations, as well as the actual entanglement entropy distribution for the random transverse-field Ising model which we calculate for large L via a mapping to Majorana fermions.

  11. Multivariate meta-analysis of prognostic factor studies with multiple cut-points and/or methods of measurement.

    PubMed

    Riley, Richard D; Elia, Eleni G; Malin, Gemma; Hemming, Karla; Price, Malcolm P

    2015-07-30

    A prognostic factor is any measure that is associated with the risk of future health outcomes in those with existing disease. Often, the prognostic ability of a factor is evaluated in multiple studies. However, meta-analysis is difficult because primary studies often use different methods of measurement and/or different cut-points to dichotomise continuous factors into 'high' and 'low' groups; selective reporting is also common. We illustrate how multivariate random effects meta-analysis models can accommodate multiple prognostic effect estimates from the same study, relating to multiple cut-points and/or methods of measurement. The models account for within-study and between-study correlations, which utilises more information and reduces the impact of unreported cut-points and/or measurement methods in some studies. The applicability of the approach is improved with individual participant data and by assuming a functional relationship between prognostic effect and cut-point to reduce the number of unknown parameters. The models provide important inferential results for each cut-point and method of measurement, including the summary prognostic effect, the between-study variance and a 95% prediction interval for the prognostic effect in new populations. Two applications are presented. The first reveals that, in a multivariate meta-analysis using published results, the Apgar score is prognostic of neonatal mortality but effect sizes are smaller at most cut-points than previously thought. In the second, a multivariate meta-analysis of two methods of measurement provides weak evidence that microvessel density is prognostic of mortality in lung cancer, even when individual participant data are available so that a continuous prognostic trend is examined (rather than cut-points).

  12. The Impact of Gait Disability on the Calibration of Accelerometer Output in Adults with Multiple Sclerosis

    PubMed Central

    Weikert, Madeline; Dlugonski, Deirdre; Suh, Yoojin; Fernhall, Bo

    2011-01-01

    Accelerometer activity counts have been correlated with energy expenditure during treadmill walking among ambulatory adults with multiple sclerosis (MS). This study examined the effects of gait disability on 1) the association between rates of energy expenditure and accelerometer output in overground walking and 2) the calibration of accelerometer output for quantifying time spent in moderate-to-vigorous physical activity (MVPA) in people with MS. The sample consisted of 24 individuals with MS, of whom 10 reported gait disability based on Patient-Determined Disease Steps (PDDS) scores. The participants undertook three 6-minute periods of overground walking while wearing an accelerometer and a portable metabolic unit (K4b2, Cosmed, Rome, Italy). In the first period of walking, the participants walked at a self-selected, comfortable speed. In the two subsequent walking periods, participants walked at speeds above and below (±0.5 mph) the comfortable walking speed, respectively. Strong linear relationships were observed between rates of accelerometer activity counts and energy expenditure during walking in the overall sample (R2 = 0.90) and subsamples with (R2 = 0.88) and without gait disability (R2 = 0.91). The slope of the relationship was significantly steeper in the subsample with gait disability (β= 0.0049) than in the subsample without gait disability (β= 0.0026). The difference in slopes resulted in a significantly lower cut-point for MVPA (1886 vs. 2717 counts/min) in those with gait disability. These findings provide a metabolic cut-point for quantifying time spent in MVPA in people with MS, both with and without gait disability. PMID:24453722

  13. The CDC and IOTF cut points show inconsistent prevalence of underweight and overweight in chinese, indonesian, and vietnamese children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    No nationally representative data from middle and low-income countries have been analyzed to compare prevalence of underweight and overweight defined by the Centers for Disease Control and Prevention (CDC) and the International Obesity Task Force (IOTF) BMI cut points. We evaluated the consistency i...

  14. Effects of the diamond grit sizes of the commercial dental diamond points on the weight-load cutting of bovine enamel and glass-ceramic Typodont teeth.

    PubMed

    Taira, M; Wakasa, K; Yamaki, M; Matsui, A

    1990-12-01

    To evaluate the effect of the diamond grit size of commercial dental diamond points on the dental cutting, we conducted weight-load cutting tests on bovine enamel and glass-ceramic typodont teeth using 3 different diamond grit sizes and air-bearing and ball-bearing air-turbine driven handpieces. With the transverse load applied on the diamond point varied between 20 and 80 g, we measured rotational cutting speed and cutting volume. Generally, increases in applied load caused decreases in rotational cutting speed and increases in cutting volume. The intensity of this trend, however, differed between grit sizes. Regular grit diamond points most strongly showed this tendency, while super-fine grit diamond points were least affected. Fine grit diamond points behaved in a manner similar to regular grit points.

  15. WWBT? What Would Ben Think about Killer Apps, Cutting Edges, and Tipping Points in the History of Weather and Climate?

    NASA Astrophysics Data System (ADS)

    Fleming, J. R.

    2006-12-01

    This paper examines the history of weather and climate since 1706 along three intertwined analytical axes: technology (killer apps), science (cutting edges), and social issues (tipping points). For example, Franklin's best-known killer app, the lightning rod, gains added significance when seen in light of his cutting edge contributions to the science of electricity, his lifelong promotion of useful knowledge, and the societal tipping point his work triggered in our relationship to the sky. Subsequently, other major tipping points and conceptual shifts followed the introduction of telegraphy, radio, television, digital computers, and rocketry into meteorology. Following an analysis of the career and contributions of Benjamin Franklin (1706-1790), the paper examines later historical moments and watersheds, not merely in retrospect, but from the perspective of leading participants at the time. It focuses on technologies of significant promise, especially those involving electro- magnetism, up to and including the dawn of the twenty-first century, and asks playfully, "What would Ben think?"

  16. Cut-off point for WHOQOL-bref as a measure of quality of life of older adults.

    PubMed

    Silva, Patrícia Aparecida Barbosa; Soares, Sônia Maria; Santos, Joseph Fabiano Guimarães; Silva, Líliam Barbosa

    2014-06-01

    OBJECTIVE To propose a cut-off for the World Health Organization Quality of Life-Bref (WHOQOL-bref) as a predictor of quality of life in older adults.METHODS Cross-sectional study with 391 older adults registered in the Northwest Health District in Belo Horizonte, MG, Southeastern Brazil, between October 8, 2010 and May 23, 2011. The older adults' quality of life was measured using the WHOQOL-bref. The analysis was rationalized by outlining two extreme and simultaneous groups according to perceived quality of life and satisfaction with health (quality of life good/satisfactory - good or very good self-reported quality of life and being satisfied or very satisfied with health - G5; and poor/very poor quality of life - poor or very poor self-reported quality of life and feeling dissatisfied or very dissatisfied with health - G6). A Receiver-Operating Characteristic curve (ROC) was created to assess the diagnostic ability of different cut-off points of the WHOQOL-bref.RESULTS ROC curve analysis indicated a critical value 60 as the optimal cut-off point for assessing perceived quality of life and satisfaction with health. The area under the curve was 0.758, with a sensitivity of 76.8% and specificity of 63.8% for a cut-off of ≥ 60 for overall quality of life (G5) and sensitivity 95.0% and specificity of 54.4% for a cut-off of < 60 for overall quality of life (G6).CONCLUSIONS Diagnostic interpretation of the ROC curve revealed that cut-off < 60 for overall quality of life obtained excellent sensitivity and negative predictive value for tracking older adults with probable worse quality of life and dissatisfied with health.

  17. Cut-off point for WHOQOL-bref as a measure of quality of life of older adults

    PubMed Central

    Silva, Patrícia Aparecida Barbosa; Soares, Sônia Maria; Santos, Joseph Fabiano Guimarães; Silva, Líliam Barbosa

    2014-01-01

    OBJECTIVE To propose a cut-off for the World Health Organization Quality of Life-Bref (WHOQOL-bref) as a predictor of quality of life in older adults. METHODS Cross-sectional study with 391 older adults registered in the Northwest Health District in Belo Horizonte, MG, Southeastern Brazil, between October 8, 2010 and May 23, 2011. The older adults’ quality of life was measured using the WHOQOL-bref. The analysis was rationalized by outlining two extreme and simultaneous groups according to perceived quality of life and satisfaction with health (quality of life good/satisfactory – good or very good self-reported quality of life and being satisfied or very satisfied with health – G5; and poor/very poor quality of life – poor or very poor self-reported quality of life and feeling dissatisfied or very dissatisfied with health – G6). A Receiver-Operating Characteristic curve (ROC) was created to assess the diagnostic ability of different cut-off points of the WHOQOL-bref. RESULTS ROC curve analysis indicated a critical value 60 as the optimal cut-off point for assessing perceived quality of life and satisfaction with health. The area under the curve was 0.758, with a sensitivity of 76.8% and specificity of 63.8% for a cut-off of ≥ 60 for overall quality of life (G5) and sensitivity 95.0% and specificity of 54.4% for a cut-off of < 60 for overall quality of life (G6). CONCLUSIONS Diagnostic interpretation of the ROC curve revealed that cut-off < 60 for overall quality of life obtained excellent sensitivity and negative predictive value for tracking older adults with probable worse quality of life and dissatisfied with health. PMID:25119934

  18. Detection of fallen trees in ALS point clouds by learning the Normalized Cut similarity function from simulated samples

    NASA Astrophysics Data System (ADS)

    Polewski, P.; Yao, W.; Heurich, M.; Krzystek, P.; Stilla, U.

    2014-08-01

    Fallen trees participate in several important forest processes, which motivates the need for information about their spatial distribution in forest ecosystems. Several studies have shown that airborne LiDAR is a valuable tool for obtaining such information. In this paper, we propose an integrated method of detecting fallen trees from ALS point clouds based on merging small segments into entire fallen stems via the Normalized Cut algorithm. A new approach to specifying the segment similarity function for the clustering algorithm is introduced, where the attribute weights are learned from labeled data instead of being determined manually. We notice the relationship between Normalized Cut's similarity function and a class of regression models, which leads us to the idea of approximating the task of learning the similarity function with the simpler task of learning a classifier. Moreover, we set up a virtual fallen tree generation scheme to simulate complex forest scenarios with multiple overlapping fallen stems. The classifier trained on this simulated data yields a similarity function for Normalized Cut. Tests on two sample plots from the Bavarian Forest National Park with manually labeled reference data show that the trained function leads to high-quality segmentations. Our results indicate that the proposed data-driven approach can be a successful alternative to time consuming trial-and-error or grid search methods of finding good feature weights for graph cut algorithms. Also, the methodology can be generalized to other applications of graph cut clustering in remote sensing.

  19. [Receiver operating characteristic analysis and the cost--benefit analysis in determination of the optimal cut-off point].

    PubMed

    Vránová, J; Horák, J; Krátká, K; Hendrichová, M; Kovaírková, K

    2009-01-01

    An overview of the use of Receiver Operating Characteristic (ROC) analysis within medicine is provided. A survey of the theory behind the analysis is offered together with a presentation on how to create a ROC curve and how to use Cost--Benefit analysis to determine the optimal cut-off point or threshold. The use of ROC analysis is exemplified in the "Cost--Benefit analysis" section of the paper. In these examples, it can be seen that the determination of the optimal cut-off point is mainly influenced by the prevalence and the severity of the disease, by the risks and adverse events of treatment or the diagnostic testing, by the overall costs of treating true and false positives (TP and FP), and by the risk of deficient or non-treatment of false negative (FN) cases.

  20. Measuring physical activity in older adults: calibrating cut-points for the MotionWatch 8©

    PubMed Central

    Landry, Glenn J.; Falck, Ryan S.; Beets, Michael W.; Liu-Ambrose, Teresa

    2015-01-01

    Given the world’s aging population, the staggering economic impact of dementia, the lack of effective treatments, and the fact a cure for dementia is likely many years away – there is an urgent need to develop interventions to prevent or at least delay dementia’s progression. Thus, lifestyle approaches to promote healthy aging are an important line of scientific inquiry. Good sleep quality and physical activity (PA) are pillars of healthy aging, and as such, are an increasing focus for intervention studies aimed at promoting health and cognitive function in older adults. However, PA and sleep quality are difficult constructs to evaluate empirically. Wrist-worn actigraphy (WWA) is currently accepted as a valid objective measure of sleep quality. The MotionWatch 8© (MW8) is the latest WWA, replacing the discontinued Actiwatch 4 and Actiwatch 7. In the current study, concurrent measurement of WWA and indirect calorimetry was performed during 10 different activities of daily living for 23 healthy older adults (aged 57–80 years) to determine cut-points for sedentary and moderate-vigorous PA – using receiver operating characteristic curves – with the cut-point for light activity being the boundaries between sedentary and moderate to vigorous PA. In addition, simultaneous multi-unit reliability was determined for the MW8 using inter-class correlations. The current study is the first to validate MW8 activity count cut-points – for sedentary, light, and moderate to vigorous PA – specifically for use with healthy older adults. These cut-points provide important context for better interpretation of MW8 activity counts, and a greater understanding of what these counts mean in terms of PA. Hence, our results validate another level of analysis for researchers using the MW8 in studies aiming to examine PA and sleep quality concurrently in older adults. PMID:26379546

  1. Teacher Education Budget Cuts in Romania and the US: Points of Contrast and Comparison

    ERIC Educational Resources Information Center

    Ives, B.; Alama, M.; Mosora, C. L.

    2013-01-01

    Background: Budgets for teacher education programmes have been substantially reduced as a result of the global economic crisis. Purpose: The purpose of this study was to compare the teacher education budget cutting processes and procedures for universities in Romania versus one university in the United States. Sample: The data were collected from…

  2. Predictive Validity of Established Cut Points for Risk and Protective Factor Scales from the Communities That Care Youth Survey

    PubMed Central

    Brown, Eric C.; Hawkins, J. David; Arthur, Michael W.

    2012-01-01

    Community coalitions are a popular strategy to coordinate activities and resources to prevent adolescent substance use and delinquent behavior. Despite early evidence of their lack of effectiveness, a new generation of community coalitions has shown positive results in preventing youth substance use and delinquency. This success can be attributed to coalition decision making focused on reducing local risk factors and increasing local protective factors through the use of evidence-based prevention programs. A previous study using cross-sectional data established cut point values for scales measuring risk and protective factors on the Communities That Care Youth Survey (CTCYS) to identify high levels of risk and low levels of protection in communities on each scale. The current study extended this previous research by using longitudinal data to assess the validity of risk and protective factor cut point values in predicting substance use and delinquent behavior 1 year after risk and protection were measured. The findings demonstrate the predictive validity of cut points for risk and protective factor scales measured by the CTCYS and suggest their utility in guiding prevention efforts. PMID:23143070

  3. Establishment of a cut-point value of serum TNF-alpha levels in the metabolic syndrome.

    PubMed

    Gurrola-Díaz, Carmen M; Sánchez-Enriquez, Sergio; Oregon-Romero, Edith; García-López, Pedro M; Garzón de la Mora, Pedro; Bastidas-Ramírez, Blanca E; González-Hita, Mercedes; Muñoz-Valle, José F

    2009-01-01

    Cardiovascular diseases and type 2 diabetes are the major causes of mortality in Mexico. Metabolic syndrome (MS) is a cluster of factors that increase the risk to develop such diseases. Previous studies have shown that MS is associated with high tumor necrosis factor (TNF-alpha) levels. In fact, TNF-alpha has been proposed to be a useful marker for clinical diagnosis of inflammation at an early stage. Therefore, we analyzed TNF-alpha concentrations in Mexican individuals with or without MS and related these levels to the associated MS components. Clinical, anthropometric, and biochemical data were analyzed in 41 healthy and 39 MS individuals. Individuals were similarly grouped by age and gender.The serum TNF-alpha levels measured by a highly sensitive enzyme-linked immunosorbent assay (ELISA) kit were increased significantly in MS subjects compared with healthy individuals (P<0.001). The assay showed 78.1% sensitivity and 61.5% specificity with a cut-point level of 1.36 pg/mL. TNF-alpha levels higher than the cut-point value were correlated with insulin resistance indices. These findings support the hypothesis that serum TNF-alpha concentration could be a useful marker for early MS diagnosis. Nevertheless, we suggest the establishment of specific cut-point values in each studied population to evaluate potential clinical applications.

  4. Insulin sensitivity indices: a proposal of cut-off points for simple identification of insulin-resistant subjects.

    PubMed

    Radikova, Z; Koska, J; Huckova, M; Ksinantova, L; Imrich, R; Vigas, M; Trnovec, T; Langer, P; Sebokova, E; Klimes, I

    2006-05-01

    Demanding measurement of insulin sensitivity using clamp methods does not simplify the identification of insulin resistant subjects in the general population. Other approaches such as fasting- or oral glucose tolerance test-derived insulin sensitivity indices were proposed and validated with the euglycemic clamp. Nevertheless, a lack of reference values for these indices prevents their wider use in epidemiological studies and clinical practice. The aim of our study was therefore to define the cut-off points of insulin resistance indices as well as the ranges of the most frequently obtained values for selected indices. A standard 75 g oral glucose tolerance test was carried out in 1156 subjects from a Caucasian rural population with no previous evidence of diabetes or other dysglycemias. Insulin resistance/sensitivity indices (HOMA-IR, HOMA-IR2, ISI Cederholm, and ISI Matsuda) were calculated. The 75th percentile value as the cut-off point to define IR corresponded with a HOMA-IR of 2.29, a HOMA-IR2 of 1.21, a 25th percentile for ISI Cederholm, and ISI Matsuda of 57 and 5.0, respectively. For the first time, the cut-off points for selected indices and their most frequently obtained values were established for groups of subjects as defined by glucose homeostasis and BMI. Thus, insulin-resistant subjects can be identified using this simple approach.

  5. Predictive validity of established cut points for risk and protective factor scales from the communities that care youth survey.

    PubMed

    Briney, John S; Brown, Eric C; Hawkins, J David; Arthur, Michael W

    2012-12-01

    Community coalitions are a popular strategy to coordinate activities and resources to prevent adolescent substance use and delinquent behavior. Despite early evidence of their lack of effectiveness, a new generation of community coalitions has shown positive results in preventing youth substance use and delinquency. This success can be attributed to coalition decision making focused on reducing local risk factors and increasing local protective factors through the use of evidence-based prevention programs. A previous study using cross-sectional data established cut point values for scales measuring risk and protective factors on the Communities That Care Youth Survey (CTCYS) to identify high levels of risk and low levels of protection in communities on each scale. The current study extended this previous research by using longitudinal data to assess the validity of risk and protective factor cut point values in predicting substance use and delinquent behavior 1 year after risk and protection were measured. The findings demonstrate the predictive validity of cut points for risk and protective factor scales measured by the CTCYS and suggest their utility in guiding prevention efforts.

  6. A short guide to pure point diffraction in cut-and-project sets

    NASA Astrophysics Data System (ADS)

    Richard, Christoph; Strungaru, Nicolae

    2017-04-01

    We briefly review the diffraction of quasicrystals and then give an elementary alternative proof of the diffraction formula for regular cut-and-project sets, which is based on Bochner’s theorem from Fourier analysis. This clarifies a common view that the diffraction of a quasicrystal is determined by the diffraction of its underlying lattice. To illustrate our approach, we will also treat a number of well-known explicitly solvable examples. We dedicate this work to Tony Guttmann on the occasion of his 70th birthday

  7. Bronchodilator response cut-off points and FEV 0.75 reference values for spirometry in preschoolers

    PubMed Central

    Burity, Edjane Figueiredo; Pereira, Carlos Alberto de Castro; Jones, Marcus Herbert; Sayão, Larissa Bouwman; de Andrade, Armèle Dornelas; de Britto, Murilo Carlos Amorim

    2016-01-01

    ABSTRACT Objective: To determine the cut-off points for FEV1, FEV0.75, FEV0.5, and FEF25-75% bronchodilator responses in healthy preschool children and to generate reference values for FEV0.75. Methods: This was a cross-sectional community-based study involving children 3-5 years of age. Healthy preschool children were selected by a standardized questionnaire. Spirometry was performed before and after bronchodilator use. The cut-off point of the response was defined as the 95th percentile of the change in each parameter. Results: We recruited 266 children, 160 (60%) of whom were able to perform acceptable, reproducible expiratory maneuvers before and after bronchodilator use. The mean age and height were 57.78 ± 7.86 months and 106.56 ± 6.43 cm, respectively. The success rate for FEV0.5 was 35%, 68%, and 70% in the 3-, 4-, and 5-year-olds, respectively. The 95th percentile of the change in the percentage of the predicted value in response to bronchodilator use was 11.6%, 16.0%, 8.5%, and 35.5% for FEV1, FEV0.75, FEV0.5, and FEF25-75%, respectively. Conclusions: Our results provide cut-off points for bronchodilator responsiveness for FEV1, FEV0.75, FEV0.5, and FEF25-75% in healthy preschool children. In addition, we proposed gender-specific reference equations for FEV0.75. Our findings could improve the physiological assessment of respiratory function in preschool children. PMID:27812631

  8. Double resonator cantilever accelerometer

    DOEpatents

    Koehler, D.R.

    1982-09-23

    A digital quartz accelerometer includes a pair of spaced double-ended tuning forks fastened at one end to a base and at the other end through a spacer mass. Transverse movement of the resonator members stresses one and compresses the other, providing a differential frequency output which is indicative of acceleration.

  9. Double resonator cantilever accelerometer

    DOEpatents

    Koehler, Dale R.

    1984-01-01

    A digital quartz accelerometer includes a pair of spaced double-ended tuning forks fastened at one end to a base and at the other end through a spacer mass. Transverse movement of the resonator members stresses one and compresses the other, providing a differential frequency output which is indicative of acceleration.

  10. Superconducting Rebalance Accelerometer

    NASA Technical Reports Server (NTRS)

    Torti, R. P.; Gerver, M.; Leary, K. J.; Jagannathan, S.; Dozer, D. M.

    1996-01-01

    A multi-axis accelerometer which utilizes a magnetically-suspended, high-TC proof mass is under development. The design and performance of a single axis device which is stabilized actively in the axial direction but which utilizes ring magnets for passive radial stabilization is discussed. The design of a full six degree-of-freedom device version is also described.

  11. Large prospective study of ovarian cancer screening in high-risk women: CA125 cut-point defined by menopausal status.

    PubMed

    Skates, Steven J; Mai, Phuong; Horick, Nora K; Piedmonte, Marion; Drescher, Charles W; Isaacs, Claudine; Armstrong, Deborah K; Buys, Saundra S; Rodriguez, Gustavo C; Horowitz, Ira R; Berchuck, Andrew; Daly, Mary B; Domchek, Susan; Cohn, David E; Van Le, Linda; Schorge, John O; Newland, William; Davidson, Susan A; Barnes, Mack; Brewster, Wendy; Azodi, Masoud; Nerenstone, Stacy; Kauff, Noah D; Fabian, Carol J; Sluss, Patrick M; Nayfield, Susan G; Kasten, Carol H; Finkelstein, Dianne M; Greene, Mark H; Lu, Karen

    2011-09-01

    Previous screening trials for early detection of ovarian cancer in postmenopausal women have used the standard CA125 cut-point of 35 U/mL, the 98th percentile in this population yielding a 2% false positive rate, whereas the same cut-point in trials of premenopausal women results in substantially higher false positive rates. We investigated demographic and clinical factors predicting CA125 distributions, including 98th percentiles, in a large population of high-risk women participating in two ovarian cancer screening studies with common eligibility criteria and screening protocols. Baseline CA125 values and clinical and demographic data from 3,692 women participating in screening studies conducted by the National Cancer Institute-sponsored Cancer Genetics Network and Gynecologic Oncology Group were combined for this preplanned analysis. Because of the large effect of menopausal status on CA125 levels, statistical analyses were conducted separately in pre- and postmenopausal subjects to determine the impact of other baseline factors on predicted CA125 cut-points on the basis of 98th percentile. The primary clinical factor affecting CA125 cut-points was menopausal status, with premenopausal women having a significantly higher cut-point of 50 U/mL, while in postmenopausal subjects the standard cut-point of 35 U/mL was recapitulated. In premenopausal women, current oral contraceptive (OC) users had a cut-point of 40 U/mL. To achieve a 2% false positive rate in ovarian cancer screening trials and in high-risk women choosing to be screened, the cut-point for initial CA125 testing should be personalized primarily for menopausal status (50 for premenopausal women, 40 for premenopausal on OC, and 35 for postmenopausal women).

  12. Low G accelerometer testing

    NASA Technical Reports Server (NTRS)

    Vaughan, M. S.

    1972-01-01

    Eight different types of low-g accelerometer tests are covered on the Bell miniature electrostatically suspended accelerometer (MESA) which is known to be sensitive to less than 10 to the minus 7th power earth's gravity. These tests include a mass attracting scheme, Leitz dividing head, Wild theodolite, precision gage blocks, precision tiltmeters, Hilger Watts autocollimator, Razdow Mark 2 autocollimator, and laser interferometer measuring system. Each test is described and a comparison of the results is presented. The output of the MESA was as linear and consistent as any of the available devices were capable of measuring. Although the extent of agreement varied with the test equipment used, it can only be concluded that the indicated errors were attributable to the test equipment coupled with the environmental conditions.

  13. Fiber optic micro accelerometer

    DOEpatents

    Swierkowski, Steve P.

    2005-07-26

    An accelerometer includes a wafer, a proof mass integrated into the wafer, at least one spring member connected to the proof mass, and an optical fiber. A Fabry-Perot cavity is formed by a partially reflective surface on the proof mass and a partially reflective surface on the end of the optical fiber. The two partially reflective surfaces are used to detect movement of the proof mass through the optical fiber, using an optical detection system.

  14. Levitated micro-accelerometer.

    SciTech Connect

    Warne, Larry Kevin; Schmidt, Carrie Frances; Peterson, Kenneth Allen; Kravitz, Stanley H.; Renn, Rosemarie A.; Peter, Frank J.; Kinney, Ragon D.; Gilkey, Jeffrey C.

    2004-06-01

    The objective is a significant advancement in the state-of-the-art of accelerometer design for tactical grade (or better) applications. The design goals are <1 milli-G bias stability across environments and $200 cost. This quantum leap in performance improvement and cost reduction can only be achieved by a radical new approach, not incremental improvements to existing concepts. This novel levitated closed-loop accelerometer is implemented as a hybrid micromachine. The hybrid approach frees the designer from the limitations of any given monolithic process and dramatically expands the available design space. The design can be tailored to the dynamic range, resolution, bandwidth, and environmental requirements of the application while still preserving all of the benefits of monolithic MEMS fabrication - extreme precision, small size, low cost, and low power. An accelerometer was designed and prototype hardware was built, driving the successful development and refinement of several 'never been done before' fabrication processes. Many of these process developments are commercially valuable and are key enablers for the realization of a wide variety of useful micro-devices. While controlled levitation of a proof mass has yet to be realized, the overall design concept remains sound. This was clearly demonstrated by the stable and reliable closed-loop control of a proof mass at the test structure level. Furthermore, the hybrid MEMS implementation is the most promising approach for achieving the ambitious cost and performance targets. It is strongly recommended that Sandia remain committed to the original goal.

  15. A Simple Accelerometer Calibrator

    NASA Astrophysics Data System (ADS)

    Salam, R. A.; Islamy, M. R. F.; Munir, M. M.; Latief, H.; Irsyam, M.; Khairurrijal

    2016-08-01

    High possibility of earthquake could lead to the high number of victims caused by it. It also can cause other hazards such as tsunami, landslide, etc. In that case it requires a system that can examine the earthquake occurrence. Some possible system to detect earthquake is by creating a vibration sensor system using accelerometer. However, the output of the system is usually put in the form of acceleration data. Therefore, a calibrator system for accelerometer to sense the vibration is needed. In this study, a simple accelerometer calibrator has been developed using 12 V DC motor, optocoupler, Liquid Crystal Display (LCD) and AVR 328 microcontroller as controller system. The system uses the Pulse Wave Modulation (PWM) form microcontroller to control the motor rotational speed as response to vibration frequency. The frequency of vibration was read by optocoupler and then those data was used as feedback to the system. The results show that the systems could control the rotational speed and the vibration frequencies in accordance with the defined PWM.

  16. Metabolic Thresholds and Validated Accelerometer Cutoff Points for the Actigraph GT1M in Young Children Based on Measurements of Locomotion and Play Activities

    ERIC Educational Resources Information Center

    Jimmy, Gerda; Dossegger, Alain; Seiler, Roland; Mader, Urs

    2012-01-01

    The purpose of the current study was to determine metabolic thresholds and subsequent activity intensity cutoff points for the ActiGraph GT1M with various epochs spanning from 5 to 60 sec in young children. Twenty-two children, aged 4 to 9 years, performed 10 different activities including locomotion and play activities. Energy expenditure was…

  17. Cut points for mild, moderate, and severe pain on the VAS for children and adolescents: what can be learned from 10 million ANOVAs?

    PubMed

    Hirschfeld, Gerrit; Zernikow, Boris

    2013-12-01

    Cut points that classify pain intensity into mild, moderate, and severe levels are widely used in pain research and clinical practice. At present, there are no agreed-upon cut points for the visual analog scale (VAS) in pediatric samples. We applied a method based on Serlin and colleagues' procedure (Serlin RC, Mendoza TR, Nakamura Y, Edwards KR, Cleeland CS. When is cancer pain mild, moderate or severe? Grading pain severity by its interference with function. PAIN(®) 1995;61:277-84) that was previously only used for the 0 to 10 numerical rating scale to empirically establish optimal cut points (OCs) for the VAS and used bootstrapping to estimate the variability of these thresholds. We analyzed data from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) study and defined OCs both for parental ratings of their children's pain and adolescents' self-ratings of pain intensity. Data from 2276 children (3 to 10 years; 54% female) and 2982 adolescents (11 to 17 years; 61% female) were analyzed. OCs were determined in a by-millimeter analysis that tested all possible 4851 OC combinations, and a truncated analysis were OCs were spaced 5 mm apart, resulting in 171 OC combinations. The OC method identified 2 different OCs for parental ratings and self-report, both in the by-millimeter and truncated analyses. When we estimated the variability of the by-millimeter analysis, we found that the specific OCs were only found in 11% of the samples. The truncated analysis revealed, however, that cut points of 35:60 are identified as optimal in both samples and are a viable alternative to separate cut points. We found a set of cut points that can be used both parental ratings of their children's pain and self-reports for adolescents. Adopting these cut points greatly enhances the comparability of trials. We call for more systematic assessment of diagnostic procedures in pain research.

  18. The current waist circumference cut point used for the diagnosis of metabolic syndrome in sub-Saharan African women is not appropriate.

    PubMed

    Crowther, Nigel J; Norris, Shane A

    2012-01-01

    The waist circumference cut point for diagnosing the metabolic syndrome in sub-Saharan African subjects is based on that obtained from studies in European populations. The aim of this study was to measure the prevalence of obesity and related metabolic disorders in an urban population of African females, a group at high risk for such diseases, and to determine the appropriate waist cut point for diagnosing the metabolic syndrome. Anthropometry and fasting lipid, glucose and insulin levels were measured in a cohort of 1251 African females participating in the Birth to Twenty cohort study in Soweto, Johannesburg. The waist circumference cut points for diagnosing metabolic syndrome (as defined using the new harmonised guidelines), insulin resistance, dysglycaemia, hypertension and dyslipidaemia were obtained using receiver operator characteristic curve analysis. The prevalence of obesity, type 2 diabetes and metabolic syndrome were 50.1%, 14.3% and 42.1%, respectively. The appropriate waist cut point for diagnosing metabolic syndrome was found to be 91.5 cm and was similar to the cuts points obtained for detecting increased risk of insulin resistance (89.0 cm), dysglycaemia (88.4 cm), hypertension (90.1 cm), hypo-high density lipoproteinaemia (87.6 cm) and hyper-low density lipoproteinaemia (90.5 cm). The present data demonstrates that urban, African females have a high prevalence of obesity and related disorders and the waist cut point currently recommended for the diagnosis of the metabolic syndrome (80.0 cm) in this population should be increased to 91.5 cm. This latter finding demonstrates a clear ethnic difference in the relationship between abdominal adiposity and metabolic disease risk. The similar waist cut points identified for the detection of the individual components of the metabolic syndrome and related cardiovascular risk factors demonstrates that the risk for different metabolic diseases increases at the same level of abdominal adiposity suggesting a

  19. Calibration and Cross-Validation of the ActiGraph wGT3X+ Accelerometer for the Estimation of Physical Activity Intensity in Children with Intellectual Disabilities

    PubMed Central

    McGarty, Arlene M.; Penpraze, Victoria; Melville, Craig A.

    2016-01-01

    Background Valid objective measurement is integral to increasing our understanding of physical activity and sedentary behaviours. However, no population-specific cut points have been calibrated for children with intellectual disabilities. Therefore, this study aimed to calibrate and cross-validate the first population-specific accelerometer intensity cut points for children with intellectual disabilities. Methods Fifty children with intellectual disabilities were randomly assigned to the calibration (n = 36; boys = 28, 9.53±1.08yrs) or cross-validation (n = 14; boys = 9, 9.57±1.16yrs) group. Participants completed a semi-structured school-based activity session, which included various activities ranging from sedentary to vigorous intensity. Direct observation (SOFIT tool) was used to calibrate the ActiGraph wGT3X+, which participants wore on the right hip. Receiver Operating Characteristic curve analyses determined the optimal cut points for sedentary, moderate, and vigorous intensity activity for the vertical axis and vector magnitude. Classification agreement was investigated using sensitivity, specificity, total agreement, and Cohen’s kappa scores against the criterion measure of SOFIT. Results The optimal (AUC = .87−.94) vertical axis cut points (cpm) were ≤507 (sedentary), 1008−2300 (moderate), and ≥2301 (vigorous), which demonstrated high sensitivity (81−88%) and specificity (81−85%). The optimal (AUC = .86−.92) vector magnitude cut points (cpm) of ≤1863 (sedentary), 2610−4214 (moderate), and ≥4215 (vigorous) demonstrated comparable, albeit marginally lower, accuracy than the vertical axis cut points (sensitivity = 80−86%; specificity = 77−82%). Classification agreement ranged from moderate to almost perfect (κ = .51−.85) with high sensitivity and specificity, and confirmed the trend that accuracy increased with intensity, and vertical axis cut points provide higher classification agreement than vector magnitude cut points

  20. Validity of a Wearable Accelerometer Device to Measure Average Acceleration Values During High-Speed Running.

    PubMed

    Alexander, Jeremy P; Hopkinson, Trent L; Wundersitz, Daniel W T; Serpell, Benjamin G; Mara, Jocelyn K; Ball, Nick B

    2016-11-01

    Alexander, JP, Hopkinson, TL, Wundersitz, DWT, Serpell, BG, Mara, JK, and Ball, NB. Validity of a wearable accelerometer device to measure average acceleration values during high-speed running. J Strength Cond Res 30(11): 3007-3013, 2016-The aim of this study was to determine the validity of an accelerometer to measure average acceleration values during high-speed running. Thirteen subjects performed three sprint efforts over a 40-m distance (n = 39). Acceleration was measured using a 100-Hz triaxial accelerometer integrated within a wearable tracking device (SPI-HPU; GPSports). To provide a concurrent measure of acceleration, timing gates were positioned at 10-m intervals (0-40 m). Accelerometer data collected during 0-10 m and 10-20 m provided a measure of average acceleration values. Accelerometer data was recorded as the raw output and filtered by applying a 3-point moving average and a 10-point moving average. The accelerometer could not measure average acceleration values during high-speed running. The accelerometer significantly overestimated average acceleration values during both 0-10 m and 10-20 m, regardless of the data filtering technique (p < 0.001). Body mass significantly affected all accelerometer variables (p < 0.10, partial η = 0.091-0.219). Body mass and the absence of a gravity compensation formula affect the accuracy and practicality of accelerometers. Until GPSports-integrated accelerometers incorporate a gravity compensation formula, the usefulness of any accelerometer-derived algorithms is questionable.

  1. Age-related differences in recommended anthropometric cut-off point validity to identify cardiovascular risk factors in ostensibly healthy women

    PubMed Central

    Björkelund, Cecilia; Guo, Xinxin; Skoog, Ingmar; Bosaeus, Ingvar; Lissner, Lauren

    2014-01-01

    Aim: To investigate validity of widely recommended anthropometric and total fat percentage cut-off points in screening for cardiovascular risk factors in women of different ages. Methods: A population-based sample of 1002 Swedish women aged 38, 50, 75 (younger, middle-aged and elderly, respectively) underwent anthropometry, health examinations and blood tests. Total fat was estimated (bioimpedance) in 670 women. Sensitivity, specificity of body mass index (BMI; ≥25 and ≥30), waist circumference (WC; ≥80 cm and ≥88 cm) and total fat percentage (TF; ≥35%) cut-off points for cardiovascular risk factors (dyslipidaemias, hypertension and hyperglycaemia) were calculated for each age. Cut-off points yielding high sensitivity together with modest specificity were considered valid. Women reporting hospital admission for cardiovascular disease were excluded. Results: The sensitivity of WC ≥80 cm for one or more risk factors was ~60% in younger and middle-aged women, and 80% in elderly women. The specificity of WC ≥80 cm for one or more risk factors was 69%, 57% and 40% at the three ages (p < .05 for age trends). WC ≥80 cm yielded ~80% sensitivity for two or more risk factors across all ages. However, specificity decreased with increasing age (p < .0001), being 33% in elderly. WC ≥88 cm provided better specificity in elderly women. BMI and TF % cut-off points were not better than WC. Conclusions: Validity of recommended anthropometric cut-off points in screening asymptomatic women varies with age. In younger and middle-age, WC ≥80 cm yielded high sensitivity and modest specificity for two or more risk factors, however, sensitivity for one or more risk factor was less than optimal. WC ≥88 cm showed better validity than WC ≥80 cm in elderly. Our results support age-specific screening cut-off points for women. PMID:25294689

  2. Single-Axis Accelerometer

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis Stephen (Inventor); Capo-Lugo, Pedro A. (Inventor)

    2016-01-01

    A single-axis accelerometer includes a housing defining a sleeve. An object/mass is disposed in the sleeve for sliding movement therein in a direction aligned with the sleeve's longitudinal axis. A first piezoelectric strip, attached to a first side of the object and to the housing, is longitudinally aligned with the sleeve's longitudinal axis. The first piezoelectric strip includes a first strip of a piezoelectric material with carbon nanotubes substantially aligned along a length thereof. A second piezoelectric strip, attached to a second side of the object and to the housing, is longitudinally aligned with the sleeve's longitudinal axis. The second piezoelectric strip includes a second strip of the piezoelectric material with carbon nanotubes substantially aligned along a length thereof. A voltage sensor is electrically coupled to at least one of the first and second piezoelectric strips.

  3. A mechanical filter for FBG accelerometers

    NASA Astrophysics Data System (ADS)

    Bocciolone, Marco; Bucca, Giuseppe; Collina, Andrea; Comolli, Lorenzo

    2014-05-01

    Many applications are characterized by very severe environment from the sensors point of view. An example is the railway field, where often the measurement setup is subjected to high voltage and electromagnetic emission. In these work conditions, optical sensors are more suitable than electrical ones due to their characteristics. In this paper, the acceleration measurements are taken into account. Nowadays many optical accelerometers are present on the market. In particular, in this work FBG accelerometers are considered. This kind of sensors is characterized by an undamped resonance that can produce the break of the sensor. One possibility to avoid this problem is to add a damping effect in order to reduce the resonance amplification. In the following section, the method to reproduce a mechanical filter able to increase the damping coefficient of the sensor is presented. Experimental results in laboratory will be discussed, showing the effectiveness of the solution.

  4. Cutting assembly

    DOEpatents

    Racki, Daniel J.; Swenson, Clark E.; Bencloski, William A.; Wineman, Arthur L.

    1984-01-01

    A cutting apparatus includes a support table mounted for movement toward and away from a workpiece and carrying a mirror which directs a cutting laser beam onto the workpiece. A carrier is rotatably and pivotally mounted on the support table between the mirror and workpiece and supports a conduit discharging gas toward the point of impingement of the laser beam on the workpiece. Means are provided for rotating the carrier relative to the support table to place the gas discharging conduit in the proper positions for cuts made in different directions on the workpiece.

  5. Identification of cut-points in commonly used hip osteoarthritis-related outcome measures that define the patient acceptable symptom state (PASS).

    PubMed

    Emerson Kavchak, Alicia J; Cook, Chad; Hegedus, Eric J; Wright, Alexis A

    2013-11-01

    To determine patient acceptable symptom state (PASS) estimates in outcome measures commonly used in hip osteoarthritis (OA). Identification of cut-points on commonly used outcome measures associated with patient satisfaction with their current state of health. As part of a randomized controlled trial, 70 patients with a clinical diagnosis of hip OA undergoing a 9-session physiotherapy treatment program completed four physical performance measures and three self-report measures at 9 weeks and 1 year. Upon completion of treatment, patients assessed their current health status according to the PASS question. Cut-points were estimated using receiver operating characteristic curves (anchor-based method), based on the patient's response to the PASS question. At 9 weeks and 1 year, identified cut-points were, respectively, ≤10 and ≤11 for the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale; ≤35 and ≤40 on the WOMAC physical function subscale; ≥+5 and ≥+6 on the global rating of change score; ≤6.05 and ≤5.30 s for the timed-up-and-go; ≤28.3 and ≤24.9 for the 40-m self-paced walk test; ≥11 and ≥12 repetitions for the 30-s chair stand test; and ≥46 repetitions for the 20-cm step test. Initial target cut-points signaling patient satisfaction with their current symptom state following physiotherapy in patients with hip osteoarthritis were determined for seven outcome measures over 1 year.

  6. Age, sex and ethnic differences in the prevalence of underweight and overweight, defined by using the CDC and IOTF cut points in Asian culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    No nationally representative data from middle- and low-income countries have been analyzed to compare the prevalence of underweight and overweight, defined by using the Centers for Disease Control and Prevention (CDC), and the International Obesity TaskForce (IOTF) body mass index cut points. To exa...

  7. Epidemiologic Behavior and Estimation of an Optimal Cut-Off Point for Homeostasis Model Assessment-2 Insulin Resistance: A Report from a Venezuelan Population

    PubMed Central

    Bermúdez, Valmore; Martínez, María Sofía; Apruzzese, Vanessa; Chávez-Castillo, Mervin; Gonzalez, Robys; Torres, Yaquelín; Bello, Luis; Añez, Roberto; Chacín, Maricarmen; Toledo, Alexandra; Cabrera, Mayela; Mengual, Edgardo; Ávila, Raquel; López-Miranda, José

    2014-01-01

    Background. Mathematical models such as Homeostasis Model Assessment have gained popularity in the evaluation of insulin resistance (IR). The purpose of this study was to estimate the optimal cut-off point for Homeostasis Model Assessment-2 Insulin Resistance (HOMA2-IR) in an adult population of Maracaibo, Venezuela. Methods. Descriptive, cross-sectional study with randomized, multistaged sampling included 2,026 adult individuals. IR was evaluated through HOMA2-IR calculation in 602 metabolically healthy individuals. For cut-off point estimation, two approaches were applied: HOMA2-IR percentile distribution and construction of ROC curves using sensitivity and specificity for selection. Results. HOMA2-IR arithmetic mean for the general population was 2.21 ± 1.42, with 2.18 ± 1.37 for women and 2.23 ± 1.47 for men (P = 0.466). When calculating HOMA2-IR for the healthy reference population, the resulting p75 was 2.00. Using ROC curves, the selected cut-off point was 1.95, with an area under the curve of 0.801, sensibility of 75.3%, and specificity of 72.8%. Conclusions. We propose an optimal cut-off point of 2.00 for HOMA2-IR, offering high sensitivity and specificity, sufficient for proper assessment of IR in the adult population of our city, Maracaibo. The determination of population-specific cut-off points is needed to evaluate risk for public health problems, such as obesity and metabolic syndrome. PMID:27379332

  8. The CRAFFT cut-points and DSM-5 criteria for alcohol and other drugs: A re-evaluation and re-examination

    PubMed Central

    Mitchell, Shannon Gwin; Kelly, Sharon M.; Gryczynski, Jan; Myers, C. Patrick; O’Grady, Kevin E.; Kirk, Arethusa S.; Schwartz, Robert P.

    2014-01-01

    Background: The CRAFFT, previously validated against DSM-IV diagnostic criteria, is the most widely used screening instrument for alcohol and other substance misuse in adolescents. The present secondary analysis study sought to compare the CRAFFT with the new DSM-5 diagnostic criteria in order to assess the CRAFFT’s psychometric properties and determine the optimal cut-point for identifying adolescents in need of further assessment. Methods: Participants were primary care patients ages 12-17 (N=525) who were recruited while waiting for a medical appointment in an urban federally qualified health center in Baltimore, Maryland, USA. Participants were administered the CRAFFT and the Composite International Diagnostic Interview, second edition, modified to include the new DSM-5 craving item. We examined the performance of the CRAFFT in identifying any problem use (defined as 1 or more DSM-5 criteria) and any DSM-5 substance use disorder (2 or more DSM-5 criteria) for alcohol or drugs other than tobacco. We examined sensitivity, specificity, and receiver operating characteristic areas under the curve (AUC) to determine the optimal CRAFFT cut-point(s) for predicting any problem use and any DSM-5 substance use disorder (SUD). Results: Examining the CRAFFT as a continuous measure, AUC values were 0.93 for problem use or higher, and 0.97 for DSM-5 SUD. Consistent with previously recommended cut-points for the CRAFFT, the cut-point of 2 performed optimally for identifying adolescents both exhibiting problem use of alcohol or drugs and meeting DSM-5 SUD criteria for alcohol or other drugs. Conclusions: Despite changes in the DSM substance use diagnostic criteria, the CRAFFT continues to demonstrate excellent sensitivity and specificity at its established cut-point of 2. Additional studies examining the CRAFFT in light of the new DSM-5 diagnostic criteria with more diverse populations are warranted. PMID:25036144

  9. Cut points for mild, moderate, and severe pain among cancer and non-cancer patients: a literature review.

    PubMed

    Woo, Aaron; Lechner, Breanne; Fu, Terence; Wong, C Shun; Chiu, Nicholas; Lam, Henry; Pulenzas, Natalie; Soliman, Hany; DeAngelis, Carlo; Chow, Edward

    2015-10-01

    Defining cut points (CPs) for varying levels of pain intensity is important for assessing changes in patient's functional status, and guiding the development and evaluation of treatment options. We aimed to summarize CPs identified in the literature for mild, moderate, and severe pain on the numeric rating scale (NRS), and recommend optimal CPs for cancer and non-cancer patients. We searched MEDLINE and EMBASE (inception to May 2015) for studies that used CPs to classify pain intensity on the NRS among patients with cancer or non-cancer conditions leading to acute or chronic pain. A CP was defined as the upper bound of a mild or moderate pain category. Of 1,556 identified articles, 27 were included for review. Among patients with cancer pain, mild-moderate pain CPs ranged from 1 to 4 (mean, 3.5±1.08), with CP4 being the most recommended CP (80%). For moderate-severe pain, CPs ranged from 4 to 7 (mean, 6.2±0.92), and CP6 (50%) was the optimal CPs. Among patients with non-cancer pain, mild-moderate pain CPs ranged from 2 to 5 (mean, 3.62±0.78), and CP4 was the most frequently used CP (52.9%). For moderate-severe non-cancer pain, CPs ranged from 4 to 8 (mean, 6.5±0.99), and CP6 (41.2%) was the most frequently recommended CP. A wide range of CPs for mild, moderate, and severe pain categories were identified in the literature among both cancer and non-cancer patient populations. Further studies are needed to delineate more accurate and precise CPs for pain intensity.

  10. The LISA accelerometer

    NASA Astrophysics Data System (ADS)

    Rodrigues, M.; Touboul, P.

    2003-10-01

    In the frame of investigating the fundamental nature of gravity, the Laser Interferometer Space Antenna (LISA) mission could open the way to a new kind of observations unreachable from ground. The experiment, based on a V-formation of six drag-free spacecraft, uses the cubic proof masses of inertial sensors to reflect the laser light, acting as reference mirrors of a 5 × 10 9 m arm length interferometer. The proof masses are also used as inertial references for the drag-free control of the spacecraft which constitute in return a shield against external forces. Derived from space electrostatic accelerometers developed at ONERA, such as GRADIO for the ESA ARISTOTELES and now GOCE mission (Bernard and Touboul, 1991), the proposed LISA sensor should shield its proof mass from any accelerometric disturbance at a level of 10 -15ms-2Hz- 1/2. The accurate capacitive sensing of the mass provides its position relative to the satellite with a resolution better than 10 -9m Hz- 1/2 in order to control the satellite orbit and to minimise the disturbances induced by the satellite self gravity or by the proof mass charge. The sensor configuration and accomodation has to be specifically optimised for the mission requirements. Fortunately, the sensor will benefit from the thermal stability of the LISA optical bench environment, i.e. 10 -6K Hz- 1/2, and of the selected materials that exhibit a very low coefficient of thermal expansion (CTE), ensuring a high geometrical stability. Apart from the modeling and the evaluation of the flight characteristics, the necessary indirect ground demonstration of the performance and the interfaces with the drag-free control will have to be considered in detail in the future.

  11. Accelerometer Method and Apparatus for Integral Display and Control Functions

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor)

    1998-01-01

    Method and apparatus for detecting mechanical vibrations and outputting a signal in response thereto is discussed. An accelerometer package having integral display and control functions is suitable for mounting upon the machinery to be monitored. Display circuitry provides signals to a bar graph display which may be used to monitor machine conditions over a period of time. Control switches may be set which correspond to elements in the bar graph to provide an alert if vibration signals increase in amplitude over a selected trip point. The circuitry is shock mounted within the accelerometer housing. The method provides for outputting a broadband analog accelerometer signal, integrating this signal to produce a velocity signal, integrating and calibrating the velocity signal before application to a display driver, and selecting a trip point at which a digitally compatible output signal is generated.

  12. Measurement of Impact Acceleration: Mouthpiece Accelerometer Versus Helmet Accelerometer

    PubMed Central

    Higgins, Michael; Halstead, P. David; Snyder-Mackler, Lynn; Barlow, David

    2007-01-01

    Context: Instrumented helmets have been used to estimate impact acceleration imparted to the head during helmet impacts. These instrumented helmets may not accurately measure the actual amount of acceleration experienced by the head due to factors such as helmet-to-head fit. Objective: To determine if an accelerometer attached to a mouthpiece (MP) provides a more accurate representation of headform center of gravity (HFCOG) acceleration during impact than does an accelerometer attached to a helmet fitted on the headform. Design: Single-factor research design in which the independent variable was accelerometer position (HFCOG, helmet, MP) and the dependent variables were g and Severity Index (SI). Setting: Independent impact research laboratory. Intervention(s): The helmeted headform was dropped (n = 168) using a National Operating Committee on Standards for Athletic Equipment (NOCSAE) drop system from the standard heights and impact sites according to NOCSAE test standards. Peak g and SI were measured for each accelerometer position during impact. Main Outcome Measures: Upon impact, the peak g and SI were recorded for each accelerometer location. Results: Strong relationships were noted for HFCOG and MP measures, and significant differences were seen between HFCOG and helmet g measures and HFCOG and helmet SI measures. No statistically significant differences were noted between HFCOG and MP g and SI measures. Regression analyses showed a significant relationship between HFCOG and MP measures but not between HFCOG and helmet measures. Conclusions: Upon impact, MP acceleration (g) and SI measurements were closely related to and more accurate in measuring HFCOG g and SI than helmet measurements. The MP accelerometer is a valid method for measuring head acceleration. PMID:17597937

  13. Comparison of Interferon-γ Release Assay to Two Cut-Off Points of Tuberculin Skin Test to Detect Latent Mycobacterium tuberculosis Infection in Primary Health Care Workers

    PubMed Central

    de Souza, Fernanda Mattos; do Prado, Thiago Nascimento; Pinheiro, Jair dos Santos; Peres, Renata Lyrio; Lacerda, Thamy Carvalho; Loureiro, Rafaela Borge; Carvalho, Jose Américo; Fregona, Geisa; Dias, Elias Santos; Cosme, Lorrayne Beliqui; Rodrigues, Rodrigo Ribeiro; Riley, Lee Wood; Maciel, Ethel Leonor Noia

    2014-01-01

    Background An interferon-γ release assay, QuantiFERON-TB (QFT) test, has been introduced an alternative test for the diagnosis of latent Mycobacterium tuberculosis infection (LTBI). Here, we compared the performance of QFT with tuberculin skin test (TST) measured at two different cut-off points among primary health care work (HCW) in Brazil. Methods A cross-sectional study was carried out among HCWs in four Brazilian cities with a known history of high incidence of TB. Results of the QFT were compared to TST results based on both ≥5 mm and ≥10 mm as cut-off points. Results We enrolled 632 HCWs. When the cut-off value of ≥10 mm was used, agreement between QFT and TST was 69% (k = 0.31), and when the cut-off of ≥5 mm was chosen, the agreement was 57% (k = 0.22). We investigated possible factors of discordance of TST vs QFT. Compared to the TST−/QFT− group, risk factors for discordance in the TST+/QFT− group with TST cut-off of ≥5 mm included age between 41–45 years [OR = 2.70; CI 95%: 1.32–5.51] and 46–64 years [OR = 2.04; CI 95%: 1.05–3.93], BCG scar [OR = 2.72; CI 95%: 1.40–5.25], and having worked only in primary health care [OR = 2.30; CI 95%: 1.09–4.86]. On the other hand, for the cut-off of ≥10 mm, BCG scar [OR = 2.26; CI 95%: 1.03–4.91], being a household contact of a TB patient [OR = 1.72; CI 95%: 1.01–2.92] and having had a previous TST [OR = 1.66; CI 95%: 1.05–2.62], were significantly associated with the TST+/QFT− group. No statistically significant associations were found among the TST−/QFT+ discordant group with either TST cut-off value. Conclusions Although we identified BCG vaccination to contribute to the discordance at both TST cut-off measures, the current Brazilian recommendation for the initiation of LTBI treatment, based on information gathered from medical history, TST, chest radiograph and physical examination, should not be changed. PMID:25137040

  14. Cut-off points for mild, moderate, and severe pain on the visual analogue scale for pain in patients with chronic musculoskeletal pain.

    PubMed

    Boonstra, Anne M; Schiphorst Preuper, Henrica R; Balk, Gerlof A; Stewart, Roy E

    2014-12-01

    The aim of this study was to find the cut-off points on the visual analogue scale (VAS) to distinguish among mild, moderate, and severe pain, in relation to the following: pain-related interference with functioning; verbal description of the VAS scores; and latent class analysis for patients with chronic musculoskeletal pain. A total of 456 patients were included. Pain was assessed using the VAS and verbal rating scale; functioning was assessed using the domains of the Short Form (36) Health Survey (SF-36). Eight cut-off point schemes were tested using multivariate analysis of variance (MANOVA), ordinal logistic regression, and latent class analysis. The study results showed that VAS scores ⩽ 3.4 corresponded to mild interference with functioning, whereas 3.5 to 6.4 implied moderate interference, and ⩾ 6.5 implied severe interference. VAS scores ⩽ 3.4 were best described for patients with chronic musculoskeletal pain as mild pain, 3.5 to 7.4 as moderate pain, and ⩾ 7.5 as severe pain. Latent class analysis found that a 3-class solution fitted best, resulting in the classes 0.1 to 3.8, 3.9 to 5.7, and 5.8 to 10 cm. Findings from our study agree with those of some other studies, although many other studies found different optimal cut-off point schemes. As there appear to be no universally accepted cut-off points, and in view of the low-to-moderate associations between VAS scores and functioning and between VAS and verbal rating scale scores, the correct classification of VAS scores as mild, moderate. or severe in clinical practice seems doubtful.

  15. Wearable accelerometer in clinical use.

    PubMed

    Tamura, Toshiyo

    2005-01-01

    To improve the equality of life, we must prevent the falls in both healthy elderly and patients with the cerebrovascular diseases. Wearable accelerometer was applied to monitor. In this paper, we introduced two different clinical applications. On is fall detector and the other is monitoring device for screening test. 1) We have developed body-worn accelerometer with data loggers and monitored the daily of life in patient with Parkinson disease. The patients wore the device and monitored falls while walking and standing. As a result, we could obtain fall times for a long period. 2) The ability of walking and standing have been evaluated by Timed up & go test. We used telemetry with accelerometer. The stability of walking could be evaluated by the acceleration signals. The simple body-won device can be useful for fall study.

  16. Assessment of the MyWellness Key accelerometer in people with type 2 diabetes.

    PubMed

    McGinley, Samantha Kate; Armstrong, Marni J; Khandwala, Farah; Zanuso, Silvano; Sigal, Ronald J

    2015-11-01

    Accelerometers are designed to measure physical activity (PA) objectively. The MyWellness Key (MWK) accelerometer has been validated primarily in younger, normal-weight populations. The aims of this study were to examine the accuracy of the MWK against directly measured lab-based exercise and free-living PA in people with type 2 diabetes, many of whom are older and overweight or obese. Thirty-five participants with type 2 diabetes completed the protocol, which included a laboratory-based session and a free-living phase. In the laboratory visit, participants completed a structured treadmill protocol wearing MWKs on each hip (all subjects) and bra cup (women only). The speed where each MWK switched from recording light- to moderate-intensity activity was determined for each MWK worn. In the free-living phase, participants wore the MWK for all waking hours for 2 weeks, and recorded exercise in PA diaries immediately after each exercise session. The mean cut-points between low ("Free") and moderate ("Play") intensity for the right and left waist-worn MWKs were 4.1 ± 0.5 km/h and 5.0 ± 0.9 km/h for the bra-mounted MWK; ideal cut-point would be 4.0 km/h. In the free-living phase, the Spearman correlation between PA according to PA diary and the waist-worn MWK was 0.81 (95% confidence interval (CI): 0.76, 0.85; P < 0.001), but only 0.66 (95% CI: 0.53, 0.77; P < 0.001) when on the bra. In conclusion, the waist-worn MWK measured PA volume accurately, and was acceptably accurate at discriminating between low- and moderate-intensity PA in people with type 2 diabetes. The MWK underestimated PA volume and intensity when worn on a bra.

  17. In-fiber integrated accelerometer.

    PubMed

    Peng, Feng; Yang, Jun; Li, Xingliang; Yuan, Yonggui; Wu, Bing; Zhou, Ai; Yuan, Libo

    2011-06-01

    A compact in-fiber integrated fiber-optic Michelson interferometer based accelerometer is proposed and investigated. In the system, the sensing element consists of a twin-core fiber acting as a bending simple supported beam. By demodulating the optical phase shift, we obtain that the acceleration is proportional to the force applied on the central position of the twin-core fiber. A simple model has been established to calculate the sensitivity and resonant frequency. The experimental results show that such an accelerometer has a sensitivity of 0.09 rad/g at the resonant frequency of 680 Hz.

  18. Accelerometer having integral fault null

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor)

    1995-01-01

    An improved accelerometer is introduced. It comprises a transducer responsive to vibration in machinery which produces an electrical signal related to the magnitude and frequency of the vibration; and a decoding circuit responsive to the transducer signal which produces a first fault signal to produce a second fault signal in which ground shift effects are nullified.

  19. Variometric Tests for Accelerometer Sensors

    NASA Astrophysics Data System (ADS)

    D'Urso, M. G.; Barbati, N.

    2012-07-01

    This paper has been re-published as: VARIOMETRIC TESTS FOR ACCELEROMETER SENSORS M. G. D'Urso and N. Barbati ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, I-4, 2012 Page(s) 315-320

  20. Prevalence of body mass index and body weight cut-off points for in vitro fertilization treatment at U.S. clinics and current clinic weight loss strategy recommendations.

    PubMed

    Turner-McGrievy, Gabrielle M; Grant, Breănna L

    2015-09-01

    The goal of this study was to determine how many clinics providing in vitro fertilization (IVF) in the United States require a body mass index (BMI) or body weight cut-off point to determine treatment eligibility. US clinics listed as members on the Society of Assisted Reproduction website in late 2013 were contacted by phone between January and March 2014. Clinic personnel were asked if a BMI or body weight cut-off points was used to determine IVF treatment eligibility and what strategies they recommended for their patients to achieve a healthy body weight. Of the 379 clinics contacted, 347 responded (92% response rate) and 35% (n = 120) reported using a BMI or body weight cut-off points to determine eligibility for IVF treatment. Mean BMI (± SD) cut-off points was 38.4 ± 5.2 kg/m(2) and mean body weight (± SD) cut-off points was 130.2 ± 14.8 kg. Of the clinics using a set cut-off points, half (46%) provided no weight loss recommendations for patients. A sizable portion of US IVF clinics report a required or preferred BMI or body weight cut-off points for treatment. Despite this, most clinics did not provide a recommended program or approach for weight loss with very few clinics reporting an in-house program.

  1. Optimal cut points of waist circumference (WC) and visceral fat area (VFA) predicting for metabolic syndrome (MetS) in elderly population in the Korean Longitudinal Study on Health and Aging (KLoSHA).

    PubMed

    Lim, Soo; Kim, Jung Hee; Yoon, Ji Won; Kang, Seon Mee; Choi, Sung Hee; Park, Young Joo; Kim, Ki Woong; Cho, Nam Han; Shin, Hayley; Park, Kyong Soo; Jang, Hak Chul

    2012-01-01

    Optimal cut points of central obesity identifying subjects at risk for MetS were proposed ethnic-specifically, but have not been established yet. Of particular interest are the values for elderly persons, which have not been identified previously. We investigated the appropriate cut points of WC and VFA for elderly in a community-based cohort in Korea. We recruited 294 men and 313 women aged 65 or over who participated in the KLoSHA. A receiver operating characteristic (ROC) curve analysis was used to estimate the optimal cut points of WC and VFA indicative of MetS. The optimal cut points for predicting MetS were 87 cm for WC, 140 cm(2) for VFA in men, and 85 cm for WC, 100 cm(2) for VFA in women with the Youden index. Similar cut points were obtained with the closest-to-(0, 1) criterion except for VFA in men, which was 122 cm(2). When adjusted for age, exercise, smoking, and alcohol consumption, men with ≥122 cm(2) and women with ≥100 cm(2) of VFA had a higher risk of MetS than subjects with lower values. The cut points of VFA and WC at risk for MetS were higher in men than women. In this community-based elderly cohort, the optimal cut points of WC at risk for MetS were lower than the Western criteria. Compared with the cut points in middle-aged Koreans, the cut points for elderly were lower in men and similar in women.

  2. Determination of the accuracy and optimal cut-off point for ELISA test in diagnosis of human brucellosis in Iran.

    PubMed

    Hasibi, Mehrdad; Jafari, Sirus; Mortazavi, Habibollah; Asadollahi, Marjan; Esmaeeli Djavid, Gholamreza

    2013-01-01

    In endemic area the most challenging problem for brucellosis is to find a reliable diagnostic method. In this case-control study, we investigated the accuracy of ELISA test for diagnosis of human brucellosis and determined the optimal cut-off value for ELISA results in Iran. The laboratory diagnosis of brucellosis was performed by blood isolation of Brucella organism with a BACTEC 9240 system and/or detection of Brucella antibodies by standard agglutination test (titer ≥ 1:160). Serum level of ELISA IgG and ELISA IgM from 56 confirmed cases of brucellosis and 126 controls were compared with each other by Box plot graph and Receiver Operating Characteristic (ROC) curve. Box plot graphs showed the high degree of dispersion for IgG and IgM data in patients compared with all controls. We observed partially overlapping for IgM data (not for IgG) between cases and controls in graphs. The area under ROC curve for distinguishing between cases and controls was larger for IgG compared to IgM. Based on results of this study, ELISA IgG test was more reliable than ELISA IgM test in diagnosis of human brucellosis in Iran. Using a cut-off of 10 IU/ml and 50 IU/ml had most sensitivity (92.9%) and most specificity (100%) for ELISA IgG test, respectively.

  3. A Study of Point of View and Character in Preparation for Oral Performance of Cuttings from "The Optimist's Daughter."

    ERIC Educational Resources Information Center

    Snow, Nancy Hill

    In the process of perfecting oral performances of selected scenes from Eudora Welty's "The Optimist's Daughter," it is important to study point of view and character as they pertain to the play. Four aspects should be considered to understand the point of view: (1) the character's story, (2) the position from which the narrator speaks,…

  4. Multiple-stage integrating accelerometer

    DOEpatents

    Devaney, H.F.

    1984-06-27

    An accelerometer assembly is provided for use in activating a switch in response to multiple acceleration pulses in series. The accelerometer includes a housing forming a chamber. An inertial mass or piston is slidably disposed in the chamber and spring biased toward a first or reset position. A damping system is also provided to damp piston movement in response to first and subsequent acceleration pulses. Additionally, a cam, including a Z-shaped slot, and cooperating follower pin slidably received therein are mounted to the piston and the housing. The middle or cross-over leg of the Z-shaped slot cooperates with the follower pin to block or limit piston movement and prevent switch activation in response to a lone acceleration pulse. The switch of the assembly is only activated after two or more separate acceleration pulses are sensed and the piston reaches the end of the chamber opposite the reset position.

  5. Multiple-stage integrating accelerometer

    DOEpatents

    Devaney, Howard F.

    1986-01-01

    An accelerometer assembly is provided for use in activating a switch in response to multiple acceleration pulses in series. The accelerometer includes a housing forming a chamber. An inertial mass or piston is slidably disposed in the chamber and spring biased toward a first or reset position. A damping system is also provided to damp piston movement in response to first and subsequent acceleration pulses. Additionally, a cam, including a Z-shaped slot, and cooperating follower pin slidably received therein are mounted to the piston and the housing. The middle or cross-over leg of the Z-shaped slot cooperates with the follower pin to block or limit piston movement and prevent switch activation in response to a lone acceleration pulse. The switch of the assembly is only activated after two or more separate acceleration pulses are sensed and the piston reaches the end of the chamber opposite the reset position.

  6. Helmsman’s Recording Accelerometer.

    DTIC Science & Technology

    2007-11-02

    Silage , Principal Electrical Engineer Mitchell B. Oslon, Research Engineer Conrad Technologies, Inc. Station Square One, Suite 102 Paoli, PA 19301...SUBTITLE Helmsman’s Recording Accelerometer 6. AUTHOR(S) Donald F. DeCleene Mitchell B. Oslon Dennis A. Silage 7. PERFORMING ORGANIZATION NAME(S) AND...58,1995. McCreight, K. K., "Assessing the Seaworthiness of SWATH Ships," SNAME Transactions, vol. 95, pp. 189-214,1987. Silage , D., Hartmann, B

  7. Fatty acid ethyl esters in hair as alcohol markers: estimating a reliable cut-off point by evaluation of 1,057 autopsy cases.

    PubMed

    Hastedt, Martin; Bossers, Lydia; Krumbiegel, Franziska; Herre, Sieglinde; Hartwig, Sven

    2013-06-01

    Alcohol abuse is a widespread problem, especially in Western countries. Therefore, it is important to have markers of alcohol consumption with validated cut-off points. For many years research has focused on analysis of hair for alcohol markers, but data on the performance and reliability of cut-off values are still lacking. Evaluating 1,057 cases from 2005 to 2011, included a large sample group for the estimation of an applicable cut-off value when compared to earlier studies on fatty acid ethyl esters (FAEEs) in hair. The FAEEs concentrations in hair, police investigation reports, medical history, and the macroscopic and microscopic alcohol-typical results from autopsy, such as liver, pancreas, and cardiac findings, were taken into account in this study. In 80.2 % of all 1,057 cases pathologic findings that may be related to alcohol abuse were reported. The cases were divided into social drinkers (n = 168), alcohol abusers (n = 502), and cases without information on alcohol use. The median FAEEs concentration in the group of social drinkers was 0.302 ng/mg (range 0.008-14.3 ng/mg). In the group of alcohol abusers a median of 1.346 ng/mg (range 0.010-83.7 ng/mg) was found. Before June 2009 the hair FAEEs test was routinely applied to a proximal hair segment of 0-6 cm, changing to a routinely investigated hair length of 3 cm after 2009, as proposed by the Society of Hair Testing (SoHT). The method showed significant differences between the groups of social drinkers and alcoholics, leading to an improvement in the postmortem detection of alcohol abuse. Nevertheless, the performance of the method was rather poor, with an area under the curve calculated from receiver operating characteristic (ROC curve AUC) of 0.745. The optimum cut-off value for differentiation between social and chronic excessive drinking calculated for hair FAEEs was 1.08 ng/mg, with a sensitivity of 56 % and a specificity of 80 %. In relation to the "Consensus on Alcohol Markers 2012

  8. Accelerometer and strain gage evaluation

    NASA Astrophysics Data System (ADS)

    Ammerman, D. J.; Madsen, M. M.; Uncapher, W. L.; Stenberg, D. R.; Bronowski, D. R.

    1991-06-01

    This document describes the method developed by Sandia National Laboratories (SNL) to evaluate transducer used in the design certification testing of nuclear material shipping packages. This testing project was performed by SNL for the Office of Civilian Radioactive Waste Management (OCRWM). This evaluation is based on the results of tests conducted to measure ruggedness, failure frequency, repeatability, and manufacturers' calibration data under both field and laboratory conditions. The results of these tests are provided and discussed. The transducer were selected for testing by surveying cask contractors and testing facilities. Important insights relating to operational characteristics of accelerometer types were gained during field testing.

  9. Superconducting six-axis accelerometer

    NASA Technical Reports Server (NTRS)

    Paik, H. J.

    1990-01-01

    A new superconducting accelerometer, capable of measuring both linear and angular accelerations, is under development at the University of Maryland. A single superconducting proof mass is magnetically levitated against gravity or any other proof force. Its relative positions and orientations with respect to the platform are monitored by six superconducting inductance bridges sharing a single amplifier, called the Superconducting Quantum Interference Device (SQUID). The six degrees of freedom, the three linear acceleration components and the three angular acceleration components, of the platform are measured simultaneously. In order to improve the linearity and the dynamic range of the instrument, the demodulated outputs of the SQUID are fed back to appropriate levitation coils so that the proof mass remains at the null position for all six inductance bridges. The expected intrinsic noise of the instrument is 4 x 10(exp -12)m s(exp -2) Hz(exp -1/2) for linear acceleration and 3 x 10(exp -11) rad s(exp -2) Hz(exp -1/2) for angular acceleration in 1-g environment. In 0-g, the linear acceleration sensitivity of the superconducting accelerometer could be improved by two orders of magnitude. The design and the operating principle of a laboratory prototype of the new instrument is discussed.

  10. Sensitivity and Specificity Improvement in Abdominal Obesity Diagnosis Using Cluster Analysis during Waist Circumference Cut-Off Point Selection

    PubMed Central

    Bermúdez, Valmore; Añez, Roberto; Toledo, Alexandra; Bello, Luis; Apruzzese, Vanessa; González, Robys; Chacín, Maricarmen; Cabrera, Mayela; Cano, Clímaco; Velasco, Manuel; López-Miranda, José

    2015-01-01

    Introduction. The purpose of this study was to analyze the influence of metabolic phenotypes during the construction of ROC curves for waist circumference (WC) cutpoint selection. Materials and Methods. A total of 1,902 subjects of both genders were selected from the Maracaibo City Metabolic Syndrome Prevalence Study database. Two-Step Cluster Analysis (TSCA) was applied to select metabolically healthy and sick men and women. ROC curves were constructed to determine WC cutoff points by gender. Results. Through TSCA, metabolic phenotype predictive variables were selected: HOMA2-IR and HOMA2-βcell for women and HOMA2-IR, HOMA2-βcell, and TAG for men. Subjects were classified as healthy normal weight, metabolically obese normal weight, healthy and metabolically disturbed overweight, and healthy and metabolically disturbed obese. Final WC cutpoints were 91.50 cm for women (93.4% sensitivity, 93.7% specificity) and 98.15 cm for men (96% sensitivity, 99.5% specificity). Conclusions. TSCA in the selection of the groups used in ROC curves construction proved to be an important tool, aiding in the detection of MOWN and MHO which cannot be identified with WC alone. The resulting WC cutpoints were <91.00 cm for women and <98.00 cm for men. Furthermore, anthropometry is insufficient to determine healthiness, and, biochemical analysis is needed to properly filter subjects during classification. PMID:25945356

  11. Display-And-Alarm Circuit For Accelerometer

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr.

    1995-01-01

    Compact accelerometer assembly consists of commercial accelerometer retrofit with display-and-alarm circuit. Provides simple means for technician attending machine to monitor vibrations. Also simpifies automatic safety shutdown by providing local alarm or shutdown signal when vibration exceeds preset level.

  12. Micromachined high-g accelerometers: a review

    NASA Astrophysics Data System (ADS)

    Narasimhan, V.; Li, H.; Jianmin, M.

    2015-03-01

    This Topical Review reviews research and commercial development of high-g micromachined accelerometers. Emphasis is placed on different high-g sensing schemes and popular design templates used to achieve high-g sensing. Additionally, trends in high-g micromachined accelerometer development both in research and in the market are discussed.

  13. Do pencil-point spinal needles decrease the incidence of postdural puncture headache in reality? A comparative study between pencil-point 25G Whitacre and cutting-beveled 25G Quincke spinal needles in 320 obstetric patients

    PubMed Central

    Pal, Anirban; Acharya, Amita; Pal, Nidhi Dawar; Dawn, Satrajit; Biswas, Jhuma

    2011-01-01

    Background: Postdural puncture headache (PDPH) is a distressing complication of the subarachnoid block. The previous studies conducted, including the recent ones, do not conclusively prove that pencil-point spinal needles decrease the incidence of PDPH. In this study, we have tried to find out whether a pencil-point Whitacre needle is a better alternative than the classic cutting beveled, commonly used, Quincke spinal needle, in patients at risk of PDPH. Materials and Methods: Three hundred and twenty obstetric patients, 20-36 years of age, ASA I and II, posted for Cesarean section under subarachnoid block, were randomly assigned into two groups W and Q, where 25G Whitacre and 25G Quincke spinal needles were used, respectively. The primary objective of the study was to find out the difference in incidence of PDPH, if any, between the two groups, by using the t test and Chi square test. Results: The incidence of PDPH was 5% in group W and 28.12% in group Q, and the difference in incidence was statistically significant (P<0.001). Conclusion: The pencil-point 25G Whitacre spinal needle causes less incidence of PDPH compared to the classic 25G Quincke needle, and is recommended for use in patients at risk of PDPH. PMID:25885381

  14. GRADIO three-axis electrostatic accelerometers

    NASA Technical Reports Server (NTRS)

    Bernard, A.

    1987-01-01

    Dedicated accelerometers for satellite gravity gradiometry (GRADIO project) are described. The design profits from experience acquired with the CACTUS accelerometer payload of the satellite CASTOR-D5B and studies of highly accurate accelerometers for inertial navigation. The principle of operation, based on a three-axis electrostatic suspension of a cubic proof mass, is well suited for the measurements of accelerations less than 0.0001 m/sec/sec. A resolution better than 10 to the minus 11th power m/sec/sec/sq root Hz is expected.

  15. Hybridizing matter-wave and classical accelerometers

    SciTech Connect

    Lautier, J.; Volodimer, L.; Hardin, T.; Merlet, S.; Lours, M.; Pereira Dos Santos, F.; Landragin, A.

    2014-10-06

    We demonstrate a hybrid accelerometer that benefits from the advantages of both conventional and atomic sensors in terms of bandwidth (DC to 430 Hz) and long term stability. First, the use of a real time correction of the atom interferometer phase by the signal from the classical accelerometer enables to run it at best performance without any isolation platform. Second, a servo-lock of the DC component of the conventional sensor output signal by the atomic one realizes a hybrid sensor. This method paves the way for applications in geophysics and in inertial navigation as it overcomes the main limitation of atomic accelerometers, namely, the dead times between consecutive measurements.

  16. Cut-Off Points for Mild, Moderate, and Severe Pain on the Numeric Rating Scale for Pain in Patients with Chronic Musculoskeletal Pain: Variability and Influence of Sex and Catastrophizing

    PubMed Central

    Boonstra, Anne M.; Stewart, Roy E.; Köke, Albère J. A.; Oosterwijk, René F. A.; Swaan, Jeannette L.; Schreurs, Karlein M. G.; Schiphorst Preuper, Henrica R.

    2016-01-01

    Objectives: The 0–10 Numeric Rating Scale (NRS) is often used in pain management. The aims of our study were to determine the cut-off points for mild, moderate, and severe pain in terms of pain-related interference with functioning in patients with chronic musculoskeletal pain, to measure the variability of the optimal cut-off points, and to determine the influence of patients’ catastrophizing and their sex on these cut-off points. Methods: 2854 patients were included. Pain was assessed by the NRS, functioning by the Pain Disability Index (PDI) and catastrophizing by the Pain Catastrophizing Scale (PCS). Cut-off point schemes were tested using ANOVAs with and without using the PSC scores or sex as co-variates and with the interaction between CP scheme and PCS score and sex, respectively. The variability of the optimal cut-off point schemes was quantified using bootstrapping procedure. Results and conclusion: The study showed that NRS scores ≤ 5 correspond to mild, scores of 6–7 to moderate and scores ≥8 to severe pain in terms of pain-related interference with functioning. Bootstrapping analysis identified this optimal NRS cut-off point scheme in 90% of the bootstrapping samples. The interpretation of the NRS is independent of sex, but seems to depend on catastrophizing. In patients with high catastrophizing tendency, the optimal cut-off point scheme equals that for the total study sample, but in patients with a low catastrophizing tendency, NRS scores ≤ 3 correspond to mild, scores of 4–6 to moderate and scores ≥7 to severe pain in terms of interference with functioning. In these optimal cut-off schemes, NRS scores of 4 and 5 correspond to moderate interference with functioning for patients with low catastrophizing tendency and to mild interference for patients with high catastrophizing tendency. Theoretically one would therefore expect that among the patients with NRS scores 4 and 5 there would be a higher average PDI score for those with low

  17. Cut-Off Points for Mild, Moderate, and Severe Pain on the Numeric Rating Scale for Pain in Patients with Chronic Musculoskeletal Pain: Variability and Influence of Sex and Catastrophizing.

    PubMed

    Boonstra, Anne M; Stewart, Roy E; Köke, Albère J A; Oosterwijk, René F A; Swaan, Jeannette L; Schreurs, Karlein M G; Schiphorst Preuper, Henrica R

    2016-01-01

    Objectives: The 0-10 Numeric Rating Scale (NRS) is often used in pain management. The aims of our study were to determine the cut-off points for mild, moderate, and severe pain in terms of pain-related interference with functioning in patients with chronic musculoskeletal pain, to measure the variability of the optimal cut-off points, and to determine the influence of patients' catastrophizing and their sex on these cut-off points. Methods: 2854 patients were included. Pain was assessed by the NRS, functioning by the Pain Disability Index (PDI) and catastrophizing by the Pain Catastrophizing Scale (PCS). Cut-off point schemes were tested using ANOVAs with and without using the PSC scores or sex as co-variates and with the interaction between CP scheme and PCS score and sex, respectively. The variability of the optimal cut-off point schemes was quantified using bootstrapping procedure. Results and conclusion: The study showed that NRS scores ≤ 5 correspond to mild, scores of 6-7 to moderate and scores ≥8 to severe pain in terms of pain-related interference with functioning. Bootstrapping analysis identified this optimal NRS cut-off point scheme in 90% of the bootstrapping samples. The interpretation of the NRS is independent of sex, but seems to depend on catastrophizing. In patients with high catastrophizing tendency, the optimal cut-off point scheme equals that for the total study sample, but in patients with a low catastrophizing tendency, NRS scores ≤ 3 correspond to mild, scores of 4-6 to moderate and scores ≥7 to severe pain in terms of interference with functioning. In these optimal cut-off schemes, NRS scores of 4 and 5 correspond to moderate interference with functioning for patients with low catastrophizing tendency and to mild interference for patients with high catastrophizing tendency. Theoretically one would therefore expect that among the patients with NRS scores 4 and 5 there would be a higher average PDI score for those with low

  18. Calculation of the ELISA’s cut-off based on the change-point analysis method for detection of Trypanosoma cruzi infection in Bolivian dogs in the absence of controls

    PubMed Central

    Lardeux, Frédéric; Torrico, Gino; Aliaga, Claudia

    2016-01-01

    In ELISAs, sera of individuals infected by Trypanosoma cruzi show absorbance values above a cut-off value. The cut-off is generally computed by means of formulas that need absorbance readings of negative (and sometimes positive) controls, which are included in the titer plates amongst the unknown samples. When no controls are available, other techniques should be employed such as change-point analysis. The method was applied to Bolivian dog sera processed by ELISA to diagnose T. cruzi infection. In each titer plate, the change-point analysis estimated a step point which correctly discriminated among known positive and known negative sera, unlike some of the six usual cut-off formulas tested. To analyse the ELISAs results, the change-point method was as good as the usual cut-off formula of the form “mean + 3 standard deviation of negative controls”. Change-point analysis is therefore an efficient alternative method to analyse ELISA absorbance values when no controls are available. PMID:27384081

  19. Accelerometer Measurements in the Amusement Park.

    ERIC Educational Resources Information Center

    Reno, Charles; Speers, Robert R.

    1995-01-01

    Describes the use of the Texas Instruments' calculator-based laboratory (CBL) and Vernier accelerometer for measuring the vector sum of the gravitational field and the acceleration of amusement park rides. (JRH)

  20. Intensity Classification Accuracy of Accelerometer-Measured Physical Activities in Chinese Children and Youth

    ERIC Educational Resources Information Center

    Zhu, Zheng; Chen, Peijie; Zhuang, Jie

    2013-01-01

    Purpose: Many ActiGraph accelerometer cutoff points and equations have been developed to classify children and youth's physical activity (PA) into different intensity levels. Using a sample from the Chinese City Children and Youth Physical Activity Study, this study was to develop new ActiGraph cutoff points for moderate-to-vigorous physical…

  1. Optomechanical accelerometers and gravity gradiometers

    NASA Astrophysics Data System (ADS)

    Guzman Cervantes, F.; Pratt, J. R.; Taylor, J. M.

    2015-12-01

    Compact optical cavities can be combined with highly stable mechanical oscillators to yield accelerometers and gravity gradiometers of exquisite sensitivity, which are also traceable to the SI.We have incorporated Fabry-Pérot fiber-optic micro-cavities onto low-loss monolithic fused-silica mechanical oscillators for gradiometry, acceleration, and force sensing. These devices consist solely of a glass oscillator and fiber optics to inject and read out the coherent optical signal, making them very simple and compatible with space applications.We have demonstrated displacement sensitivities better than 200 am/√Hz with these fiber-optic micro-sensors. This translates into broadband acceleration noise floors below 100 nano-g/√Hz over a 10kHz, when combined with compact high frequency mechanical oscillators. Similarly, we have developed monolithic oscillators with resonance frequencies near and below 10 Hz, yielding measurement sensitivities better than 10-9 m/s2.We will introduce our sensor concepts and present results on our fiber-optic displacement sensors and novel optomechanical devices.

  2. Optomechanical accelerometers and gravity gradiometers

    NASA Astrophysics Data System (ADS)

    Guzman, Felipe

    2016-04-01

    Compact optical cavities can be combined with highly stable mechanical oscillators to yield accelerometers and gravity gradiometers of exquisite sensitivity, which are also traceable to the SI. We have incorporated Fabry-Pérot fiber-optic micro-cavities onto low-loss monolithic fused-silica mechanical oscillators for gradiometry, acceleration, and force sensing. These devices consist solely of a glass oscillator and fiber optics to inject and read out the coherent optical signal, making them very simple and compatible with space applications. We have demonstrated displacement sensitivities better than 200 am/√Hz with these fiber-optic micro-sensors. This translates into broadband acceleration noise floors below 100 nano-g/√Hz over a 10kHz, when combined with compact high frequency mechanical oscillators. Similarly, we have developed monolithic oscillators with resonance frequencies near and below 10 Hz, yielding measurement sensitivities better than 10-9 m/s2. We will introduce our sensor concepts and present results on our fiber-optic displacement sensors and novel optomechanical devices.

  3. High G MEMS integrated accelerometer

    SciTech Connect

    Davies, B.R.; Barron, C.C.; Montague, S.; Smith, J.H.; Murray, J.R.; Christenson, T.R.; Bateman, V.I.

    1996-12-31

    This paper describes the design and implementation of a surface micromachined accelerometer for measuring very high levels of acceleration (up to 50,000 G). Both the mechanical and electronic portions of the sensor were integrated on a single substrate using a process developed at Sandia National Laboratories. In this process, the mechanical components of the sensor were first fabricated at the bottom of a trench etched into the water substrate. The trench was then filled with oxide and sealed to protect the mechanical components during subsequent microelectronics processing. The wafer surface was then planarized in preparation for CMOS processing using Chemical Mechanical Polishing (CMP). Next, the CMOS electronics were fabricated on areas of the wafer adjacent to the embedded structures. Finally, the mechanical structures were released and the sensor tested. The mechanical structure of the sensor consisted of two polysilicon plate masses suspended by multiple springs (cantilevered beam structures) over corresponding polysilicon plates fixed to the substrate to form two parallel plate capacitors. The first polysilicon plate mass was suspended using compliant springs (cantilever beams) and acted as a variable capacitor during sensor acceleration. The second polysilicon plate mass was suspended using very stiff springs and acted as a fixed capacitor during acceleration. Acceleration was measured by comparing the capacitance of the variable capacitor (compliant suspension) with the fixed capacitance (stiff suspension).

  4. The Optimal Ethnic-Specific Waist-Circumference Cut-Off Points of Metabolic Syndrome among Low-Income Rural Uyghur Adults in Far Western China and Implications in Preventive Public Health

    PubMed Central

    He, Jia; Ma, Rulin; Liu, Jiaming; Zhang, Mei; Ding, Yusong; Guo, Heng; Mu, Lati; Zhang, Jingyu; Wei, Bin; Yan, Yizhong; Ma, Jiaolong; Pang, Hongrui; Li, Shugang; Guo, Shuxia

    2017-01-01

    Background: Metabolic syndrome is pandemic; however, the cut-off values for waist circumference (WC) vary widely depending on the ethnic groups studied and the criteria applied for WC measurement. Previous studies for defining optimal WC cut-off points included high-income and urban settings, and did not cover low-income, rural settings, especially for ethnic minorities. This study aimed at defining optimal ethnic-specific WC cut-off points in a low-income, rural population comprising the largest inhabitant minority group residing in far Western China. Methods: Questionnaire-based surveys, physical examinations, and blood testing of 3542 individuals were conducted in 2010, using a stratified cluster random sampling method in rural Uyghur residents (≥18 years old) from 12 villages in Xinjiang, China, approximately 4407 km away from the capital city, Beijing. Metabolic syndrome was defined according to the International Diabetes Federation (IDF) criteria. Optimal, ethnic-specific WC cut-off values for diagnosing metabolic syndrome were determined using receiver operator characteristic (ROC) curve analysis. Results: As WC increased, there was a significant, increasing trend of detection and risk in rural Uyghur adults, regardless of the presence of ≥1 or ≥2 components of metabolic syndrome by IDF criteria. The optimal ethnic-specific WC cut-off point to predict the presence of metabolic syndrome was 85 cm for men and 82 cm for women. With these cut-off points, the prevalence rates of metabolic syndrome among men, women, and overall population in Uyghur adults were 19.5%, 23.0%, and 21.3%, respectively. Conclusions: We report a high prevalence of metabolic syndrome, especially in women, among rural Uyghurs in Western China. A WC cut-off of 85 cm in men and 82 cm in women was the best predictor of metabolic syndrome in this population. Because of the cost-effectiveness in measuring WC, we recommend that these WC cut-off points be integrated into local preventive

  5. The Optimal Ethnic-Specific Waist-Circumference Cut-Off Points of Metabolic Syndrome among Low-Income Rural Uyghur Adults in Far Western China and Implications in Preventive Public Health.

    PubMed

    He, Jia; Ma, Rulin; Liu, Jiaming; Zhang, Mei; Ding, Yusong; Guo, Heng; Mu, Lati; Zhang, Jingyu; Wei, Bin; Yan, Yizhong; Ma, Jiaolong; Pang, Hongrui; Li, Shugang; Guo, Shuxia

    2017-02-08

    Background: Metabolic syndrome is pandemic; however, the cut-off values for waist circumference (WC) vary widely depending on the ethnic groups studied and the criteria applied for WC measurement. Previous studies for defining optimal WC cut-off points included high-income and urban settings, and did not cover low-income, rural settings, especially for ethnic minorities. This study aimed at defining optimal ethnic-specific WC cut-off points in a low-income, rural population comprising the largest inhabitant minority group residing in far Western China. Methods: Questionnaire-based surveys, physical examinations, and blood testing of 3542 individuals were conducted in 2010, using a stratified cluster random sampling method in rural Uyghur residents (≥18 years old) from 12 villages in Xinjiang, China, approximately 4407 km away from the capital city, Beijing. Metabolic syndrome was defined according to the International Diabetes Federation (IDF) criteria. Optimal, ethnic-specific WC cut-off values for diagnosing metabolic syndrome were determined using receiver operator characteristic (ROC) curve analysis. Results: As WC increased, there was a significant, increasing trend of detection and risk in rural Uyghur adults, regardless of the presence of ≥1 or ≥2 components of metabolic syndrome by IDF criteria. The optimal ethnic-specific WC cut-off point to predict the presence of metabolic syndrome was 85 cm for men and 82 cm for women. With these cut-off points, the prevalence rates of metabolic syndrome among men, women, and overall population in Uyghur adults were 19.5%, 23.0%, and 21.3%, respectively. Conclusions: We report a high prevalence of metabolic syndrome, especially in women, among rural Uyghurs in Western China. A WC cut-off of 85 cm in men and 82 cm in women was the best predictor of metabolic syndrome in this population. Because of the cost-effectiveness in measuring WC, we recommend that these WC cut-off points be integrated into local preventive

  6. CHAMP Tracking and Accelerometer Data Analysis Results

    NASA Technical Reports Server (NTRS)

    Lemoine, Frank G.; Luthcke, S. B.; Rowlands, D. D.; Pavlis, D. E.; Colombo, O. L.; Ray, Richard D.; Thompson, B.; Nerem, R. S.; Williams, Teresa A.; Smith, David E. (Technical Monitor)

    2002-01-01

    The CHAMP (Challenging Minisatellite Payload) mission's unique combination of sensors and orbit configuration will enable unprecedented improvements in modeling and understanding the Earth's static gravity field and its temporal variations. CHAMP is the first of two missions (GRACE (Gravity Recovery and Climate Experiment) to be launched in the later part of '01) that combine a new generation of GPS (Global Positioning System) receivers, a high precision three axis accelerometer, and star cameras for the precision attitude determination. In order to isolate the gravity signal for science investigations, it is necessary to perform a detailed reduction and analysis of the GPS and SLR tracking data in conjunction with the accelerometer and attitude data. Precision orbit determination based on the GPS and SLR (Satellite Laser Ranging) tracking data will isolate the orbit perturbations, while the accelerometer data will be used to distinguish the surface forces from those due to the geopotential (static, and time varying). In preparation for the CHAMP and GRACE missions, extensive modifications have been made to NASA/GSFC's GEODYN orbit determination software to enable the simultaneous reduction of spacecraft tracking (e.g. GPS and SLR), three axis accelerometer and precise attitude data. Several weeks of CHAMP tracking and accelerometer data have been analyzed and the results will be presented. Precision orbit determination analysis based on tracking data alone in addition to results based on the simultaneous reduction of tracking and accelerometer data will be discussed. Results from a calibration of the accelerometer will be presented along with the results from various orbit determination strategies. Gravity field modeling status and plans will be discussed.

  7. Accelerometer Placement for the International Space Station Node Modal Test

    NASA Technical Reports Server (NTRS)

    Tinker, Michael L.

    1998-01-01

    Accelerometer location analysis for the modal survey test of the International Space Station Node is described. Three different approaches were utilized: (1) Guyan reduction; (2) Iterative Guyan reduction; and (3) The average driving point residue (ADPR) method. Both Guyan approaches worked well, but poor results were observed for the ADPR method. Although the iterative Guyan approach appears to provide the best set of sensor locations, it is intensive computationally, becoming impractical for large initial location sets. While this is computer dependent, it appears that initial sets larger than about 1500 degrees of freedom are impractical for the iterative technique.

  8. Characterizing performance of ultra-sensitive accelerometers

    NASA Technical Reports Server (NTRS)

    Sebesta, Henry

    1990-01-01

    An overview is given of methodology and test results pertaining to the characterization of ultra sensitive accelerometers. Two issues are of primary concern. The terminology ultra sensitive accelerometer is used to imply instruments whose noise floors and resolution are at the state of the art. Hence, the typical approach of verifying an instrument's performance by measuring it with a yet higher quality instrument (or standard) is not practical. Secondly, it is difficult to find or create an environment with sufficiently low background acceleration. The typical laboratory acceleration levels will be at several orders of magnitude above the noise floor of the most sensitive accelerometers. Furthermore, this background must be treated as unknown since the best instrument available is the one to be tested. A test methodology was developed in which two or more like instruments are subjected to the same but unknown background acceleration. Appropriately selected spectral analysis techniques were used to separate the sensors' output spectra into coherent components and incoherent components. The coherent part corresponds to the background acceleration being measured by the sensors being tested. The incoherent part is attributed to sensor noise and data acquisition and processing noise. The method works well for estimating noise floors that are 40 to 50 dB below the motion applied to the test accelerometers. The accelerometers being tested are intended for use as feedback sensors in a system to actively stabilize an inertial guidance component test platform.

  9. Electret accelerometers: physics and dynamic characterization.

    PubMed

    Hillenbrand, J; Haberzettl, S; Motz, T; Sessler, G M

    2011-06-01

    Electret microphones are produced in numbers that significantly exceed those for all other microphone types. This is due to the fact that air-borne electret sensors are of simple and low-cost design but have very good acoustical properties. In contrast, most of the discrete structure-borne sound sensors (or accelerometers) are based on the piezoelectric effect. In the present work, capacitive accelerometers utilizing the electret principle were constructed, built, and characterized. These electret accelerometers comprise a metallic seismic mass, covered by an electret film, a ring of a soft cellular polymer supplying the restoring force, and a metallic backplate. These components replace membrane, spacer, and back electrode, respectively, of the electret microphone. An adjustable static pressure to the seismic mass is generated by two metal springs. The dynamic characterization of the accelerometers was carried out by using an electrodynamic shaker and an external charge or voltage amplifier. Sensors with various seismic masses, air gap distances, and electret voltages were investigated. Charge sensitivities from 10 to 40 pC/g, voltage sensitivities from 600 to 2000 mV/g, and resonance frequencies from 3 to 1.5 kHz were measured. A model describing both the charge and the voltage sensitivity is presented. Good agreement of experimental and calculated values is found. The experimental results show that sensitive, lightweight, and inexpensive electret accelerometers can be built.

  10. Laser Cutting

    DTIC Science & Technology

    1988-06-01

    lasers that are optically modified to produce high beam quality at reduced power levels for precision drilling and trepanning. * Nd:YAG lasers with...a smooth, dross-free cut face while the marking consists of a series of precisely placed shallow pits where surface finish and dross are not usually...neodymium:yttrium-aluminum-garnet (Nd:YAG) pulsed cutting data because the technique is considered vital in meeting the detailed precision cutting

  11. Laser cutting system

    SciTech Connect

    Dougherty, Thomas J

    2015-03-03

    A workpiece cutting apparatus includes a laser source, a first suction system, and a first finger configured to guide a workpiece as it moves past the laser source. The first finger includes a first end provided adjacent a point where a laser from the laser source cuts the workpiece, and the first end of the first finger includes an aperture in fluid communication with the first suction system.

  12. Designing Electrostatic Accelerometers for Next Gravity Missions

    NASA Astrophysics Data System (ADS)

    Huynh, Phuong-Anh; Foulon, Bernard; Christophe, Bruno; Liorzou, Françoise; Boulanger, Damien; Lebat, Vincent

    2016-04-01

    Square cuboid electrostatic accelerometers sensor core have been used in various combinations in recent and still flying missions (CHAMP, GRACE, GOCE). ONERA is now in the process of delivering such accelerometers for the GRACE Follow-On mission. The goal is to demonstrate the performance benefits of an interferometry laser ranging method for future low-low satellite to satellite missions. The electrostatic accelerometer becoming thus the system main performance limiter, we propose for future missions a new symmetry which will allow for three ultrasensitive axes instead of two. This implies no performance ground testing, as the now cubic proof-mass will be too heavy, but only free fall tests in catapult mode, taking advantage of the additional microgravity testing time offered by the updated ZARM tower. The updated mission will be in better adequacy with the requirements of a next generation of smaller and drag compensated micro-satellites. In addition to the measurement of the surface forces exerted on the spacecraft by the atmospheric drag and by radiation pressures, the accelerometer will become a major part of the attitude and orbit control system by acting as drag free sensor and by accurately measuring the angular accelerations. ONERA also works on a hybridization of the electrostatic accelerometer with an atomic interferometer to take advantage of the absolute nature of the atomic interferometer acceleration measurement and its great accuracy in the [5-100] mHz bandwidth. After a description of the improvement of the GRACE-FO accelerometer with respect to the still in-orbit previous models and a status of its development, the presentation will describe the new cubic configuration and how its operations and performances can be verified in the Bremen drop tower.

  13. Passive Accelerometer System Measurements on MIR

    NASA Technical Reports Server (NTRS)

    Alexander, J. Iwan D.

    1997-01-01

    The Passive Accelerometer System (PAS) is a simple moving ball accelerometer capable of measuring the small magnitude steady relative acceleration that occurs in a low earth orbit spacecraft due to atmospheric drag and the earth's gravity gradient. The acceleration is measured by recording the average velocity of the spherical ball over a suitable time increment. A modified form of Stokes law is used to convert the average velocity into an acceleration. PAS was used to measure acceleration on the MIR space station and on the first United States Microgravity Laboratory (USML-1). The PAS measurement on MIR revealed remarkably low acceleration levels in the SPEKTR module.

  14. Estimation of Saliva Cotinine Cut-Off Points for Active and Passive Smoking during Pregnancy-Polish Mother and Child Cohort (REPRO_PL).

    PubMed

    Polanska, Kinga; Krol, Anna; Kaluzny, Pawel; Ligocka, Danuta; Mikolajewska, Karolina; Shaheen, Seif; Walton, Robert; Hanke, Wojciech

    2016-12-08

    A reliable assessment of smoking status has significant public health implications and is essential for research purposes. The aim of this study was to determine optimal saliva cotinine cut-off values for smoking during pregnancy. The analyses were based on data from 1771 women from the Polish Mother and Child Cohort. Saliva cotinine concentrations were assessed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-ESI + MS/MS). The saliva cotinine cut-off value for active smoking was established at 10 ng/mL (sensitivity 96%, specificity 95%) and for passive smoking at 1.5 ng/mL (sensitivity 63%, specificity 71%). About 5% of the self-reported non-smoking women were classified as smokers based on the cotinine cut-off value. Significantly more younger, single, and less educated self-reported non-smokers had a cotinine concentration higher than 10 ng/mL compared to those who were older, married, and who had a university degree. Close to 30% of the non-smokers who indicated that smoking was not allowed in their home could be classified as exposed to passive smoking based on the cut-off value. The study suggests that self-reported smoking status is a valid measure of active smoking, whereas in the case of passive smoking, a combination of questionnaire data and biomarker verification may be required.

  15. Estimation of Saliva Cotinine Cut-Off Points for Active and Passive Smoking during Pregnancy—Polish Mother and Child Cohort (REPRO_PL)

    PubMed Central

    Polanska, Kinga; Krol, Anna; Kaluzny, Pawel; Ligocka, Danuta; Mikolajewska, Karolina; Shaheen, Seif; Walton, Robert; Hanke, Wojciech

    2016-01-01

    A reliable assessment of smoking status has significant public health implications and is essential for research purposes. The aim of this study was to determine optimal saliva cotinine cut-off values for smoking during pregnancy. The analyses were based on data from 1771 women from the Polish Mother and Child Cohort. Saliva cotinine concentrations were assessed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-ESI + MS/MS). The saliva cotinine cut-off value for active smoking was established at 10 ng/mL (sensitivity 96%, specificity 95%) and for passive smoking at 1.5 ng/mL (sensitivity 63%, specificity 71%). About 5% of the self-reported non-smoking women were classified as smokers based on the cotinine cut-off value. Significantly more younger, single, and less educated self-reported non-smokers had a cotinine concentration higher than 10 ng/mL compared to those who were older, married, and who had a university degree. Close to 30% of the non-smokers who indicated that smoking was not allowed in their home could be classified as exposed to passive smoking based on the cut-off value. The study suggests that self-reported smoking status is a valid measure of active smoking, whereas in the case of passive smoking, a combination of questionnaire data and biomarker verification may be required. PMID:27941658

  16. Dual Accelerometer Usage Strategy for Onboard Space Navigation

    NASA Technical Reports Server (NTRS)

    Zanetti, Renato; D'Souza, Chris

    2012-01-01

    This work introduces a dual accelerometer usage strategy for onboard space navigation. In the proposed algorithm the accelerometer is used to propagate the state when its value exceeds a threshold and it is used to estimate its errors otherwise. Numerical examples and comparison to other accelerometer usage schemes are presented to validate the proposed approach.

  17. Three-axis MEMS Accelerometer for Structural Inspection

    NASA Astrophysics Data System (ADS)

    Barbin, E.; Koleda, A.; Nesterenko, T.; Vtorushin, S.

    2016-01-01

    Microelectromechanical system accelerometers are widely used for metrological measurements of acceleration, tilt, vibration, and shock in moving objects. The paper presents the analysis of MEMS accelerometer that can be used for the structural inspection. ANSYS Multiphysics platform is used to simulate the behavior of MEMS accelerometer by employing a finite element model and MATLAB/Simulink tools for modeling nonlinear dynamic systems.

  18. Assessment of Differing Definitions of Accelerometer Nonwear Time

    ERIC Educational Resources Information Center

    Evenson, Kelly R.; Terry, James W., Jr.

    2009-01-01

    Measuring physical activity with objective tools, such as accelerometers, is becoming more common. Accelerometers measure acceleration multiple times within a given frequency and summarize this as a count over a pre-specified time period or epoch. The resultant count represents acceleration over the epoch length. Accelerometers eliminate biases…

  19. ISA accelerometer onboard the Mercury Planetary Orbiter: error budget

    NASA Astrophysics Data System (ADS)

    Iafolla, Valerio; Lucchesi, David M.; Nozzoli, Sergio; Santoli, Francesco

    2007-03-01

    We have estimated a preliminary error budget for the Italian Spring Accelerometer (ISA) that will be allocated onboard the Mercury Planetary Orbiter (MPO) of the European Space Agency (ESA) space mission to Mercury named BepiColombo. The role of the accelerometer is to remove from the list of unknowns the non-gravitational accelerations that perturb the gravitational trajectory followed by the MPO in the strong radiation environment that characterises the orbit of Mercury around the Sun. Such a role is of fundamental importance in the context of the very ambitious goals of the Radio Science Experiments (RSE) of the BepiColombo mission. We have subdivided the errors on the accelerometer measurements into two main families: (i) the pseudo-sinusoidal errors and (ii) the random errors. The former are characterised by a periodic behaviour with the frequency of the satellite mean anomaly and its higher order harmonic components, i.e., they are deterministic errors. The latter are characterised by an unknown frequency distribution and we assumed for them a noise-like spectrum, i.e., they are stochastic errors. Among the pseudo-sinusoidal errors, the main contribution is due to the effects of the gravity gradients and the inertial forces, while among the random-like errors the main disturbing effect is due to the MPO centre-of-mass displacements produced by the onboard High Gain Antenna (HGA) movements and by the fuel consumption and sloshing. Very subtle to be considered are also the random errors produced by the MPO attitude corrections necessary to guarantee the nadir pointing of the spacecraft. We have therefore formulated the ISA error budget and the requirements for the satellite in order to guarantee an orbit reconstruction for the MPO spacecraft with an along-track accuracy of about 1 m over the orbital period of the satellite around Mercury in such a way to satisfy the RSE requirements.

  20. A novel piezoresistive polymer nanocomposite MEMS accelerometer

    NASA Astrophysics Data System (ADS)

    Seena, V.; Hari, K.; Prajakta, S.; Pratap, Rudra; Ramgopal Rao, V.

    2017-01-01

    A novel polymer MEMS (micro electro mechanical systems) accelerometer with photo-patternable polymer nanocomposite as a piezoresistor is presented in this work. Polymer MEMS Accelerometer with beam thicknesses of 3.3 µm and embedded nanocomposite piezoresistive layer having a gauge factor of 90 were fabricated. The photosensitive nanocomposite samples were prepared and characterized for analyzing the mechanical and electrical properties and thereby ensuring proper process parameters for incorporating the piezoresistive layer into the polymer MEMS accelerometer. The microfabrication process flow and unit processes followed are extremely low cost with process temperatures below 100 °C. This also opens up a new possibility for easy integration of such polymer MEMS with CMOS (complementary metal oxide semiconductor) devices and circuits. The fabricated devices were characterized using laser Doppler vibrometer (LDV) and the devices exhibited a resonant frequency of 10.8 kHz and a response sensitivity of 280 nm g-1 at resonance. The main focus of this paper is on the SU-8/CB nanocomposite piezoresistive MEMS accelerometer technology development which covers the material and the fabrication aspects of these devices. CoventorWare FEA analysis performed using the extracted material properties from the experimental characterization which are in close agreement to performance parameters of the fabricated devices is also discussed. The simulated piezoresistive polymer MEMS devices showed an acceleration sensitivity of 126 nm g-1 and 82 ppm of ΔR/R per 1 g of acceleration.

  1. Micro-Accelerometers Monitor Equipment Health

    NASA Technical Reports Server (NTRS)

    2014-01-01

    Glenn Research Center awarded SBIR funding to Ann Arbor, Michigan-based Evigia Systems to develop a miniaturized accelerometer to account for gravitational effects in space experiments. The company has gone on to implement the technology in its suite of prognostic sensors, which are used to monitor the integrity of industrial machinery. As a result, five employees have been hired.

  2. Smartphone MEMS accelerometers and earthquake early warning

    NASA Astrophysics Data System (ADS)

    Kong, Q.; Allen, R. M.; Schreier, L.; Kwon, Y. W.

    2015-12-01

    The low cost MEMS accelerometers in the smartphones are attracting more and more attentions from the science community due to the vast number and potential applications in various areas. We are using the accelerometers inside the smartphones to detect the earthquakes. We did shake table tests to show these accelerometers are also suitable to record large shakings caused by earthquakes. We developed an android app - MyShake, which can even distinguish earthquake movements from daily human activities from the recordings recorded by the accelerometers in personal smartphones and upload trigger information/waveform to our server for further analysis. The data from these smartphones forms a unique datasets for seismological applications, such as earthquake early warning. In this talk I will layout the method we used to recognize earthquake-like movement from single smartphone, and the overview of the whole system that harness the information from a network of smartphones for rapid earthquake detection. This type of system can be easily deployed and scaled up around the global and provides additional insights of the earthquake hazards.

  3. Low-Cost Accelerometers for Physics Experiments

    ERIC Educational Resources Information Center

    Vannoni, Maurizio; Straulino, Samuele

    2007-01-01

    The implementation of a modern game-console controller as a data acquisition interface for physics experiments is discussed. The investigated controller is equipped with three perpendicular accelerometers and a built-in infrared camera to evaluate its own relative position. A pendulum experiment is realized as a demonstration of the proposed…

  4. Time Domain Switched Accelerometer Design and Fabrication

    DTIC Science & Technology

    2014-09-01

    TECHNICAL REPORT 2052 September 2014 Time -Domain Switched Accelerometer Design and Fabrication Paul Swanson Andrew Wang...Approved for public release. SSC Pacific San Diego, CA 92152-5001 TECHNICAL REPORT 2052 September 2014 Time ...objective of this report is to record the decision-making process for developing the device design and fabrication workflow for the time -domain switched

  5. Accelerometer-controlled automatic braking system

    NASA Technical Reports Server (NTRS)

    Dreher, R. C.; Sleeper, R. K.; Nayadley, J. R., Sr.

    1973-01-01

    Braking system, which employs angular accelerometer to control wheel braking and results in low level of tire slip, has been developed and tested. Tests indicate that system is feasible for operations on surfaces of different slipperinesses. System restricts tire slip and is capable of adapting to rapidly-changing surface conditions.

  6. Operationalizing hippocampal volume as an enrichment biomarker for amnestic mild cognitive impairment trials: effect of algorithm, test-retest variability, and cut point on trial cost, duration, and sample size.

    PubMed

    Yu, Peng; Sun, Jia; Wolz, Robin; Stephenson, Diane; Brewer, James; Fox, Nick C; Cole, Patricia E; Jack, Clifford R; Hill, Derek L G; Schwarz, Adam J

    2014-04-01

    The objective of this study was to evaluate the effect of computational algorithm, measurement variability, and cut point on hippocampal volume (HCV)-based patient selection for clinical trials in mild cognitive impairment (MCI). We used normal control and amnestic MCI subjects from the Alzheimer's Disease Neuroimaging Initiative 1 (ADNI-1) as normative reference and screening cohorts. We evaluated the enrichment performance of 4 widely used hippocampal segmentation algorithms (FreeSurfer, Hippocampus Multi-Atlas Propagation and Segmentation (HMAPS), Learning Embeddings Atlas Propagation (LEAP), and NeuroQuant) in terms of 2-year changes in Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), and Clinical Dementia Rating Sum of Boxes (CDR-SB). We modeled the implications for sample size, screen fail rates, and trial cost and duration. HCV based patient selection yielded reduced sample sizes (by ∼40%-60%) and lower trial costs (by ∼30%-40%) across a wide range of cut points. These results provide a guide to the choice of HCV cut point for amnestic MCI clinical trials, allowing an informed tradeoff between statistical and practical considerations.

  7. Comparing the 7-Day PAR with a Triaxial Accelerometer for Measuring Time in Exercise

    PubMed Central

    Sloane, Richard; Snyder, Denise Clutter; Demark-Wahnefried, Wendy; Lobach, David; Kraus, William E.

    2009-01-01

    Purpose The primary study aim was to evaluate associations of estimated weekly minutes of moderate-to-vigorous intensity exercise from self-reports of the telephone-administered 7-Day Physical Activity Recall (PAR) with data captured by the RT3 triaxial accelerometer. Methods This investigation was undertaken as part of the FRESH START study, a randomized clinical trial that tested an iteratively-tailored diet and exercise mailed print intervention among newly diagnosed breast and prostate cancer survivors. A convenience sample of 139 medically-eligible subjects living within a 60-mile radius of the study center provided both 7-Day PAR and accelerometer data at enrollment. Ultimately n=115 substudy subjects were found eligible for the FRESH START study and randomized to one of two study treatment arms. Follow-up assessments at Year 1 (n=103) and Year 2 (n=99) provided both the 7-Day PAR and accelerometer data. Results There was moderate agreement between the 7-Day PAR and the accelerometer with longitudinal serial correlation coefficients of .54 (baseline), .24 (Year 1) and .53 (Year 2), all P-values < .01, though the accelerometer estimates for weekly time in moderate-to-vigorous physical activity were much higher than those of the 7-Day PAR at all time points. The two methods were poorly correlated in assessing sensitivity to change from baseline to Year 1 (rho=.11, P=.30). Using mixed models repeated measures analysis, both methods exhibited similar non-significant treatment arm X time interaction P-values (7-Day PAR=.22, accelerometer=.23). Conclusions The correlations for three serial time points were in agreement with findings of other studies that compared self-reported time in exercise with physical activity captured by accelerometry. However, these methods capture somewhat different dimensions of physical activity and provide differing estimates of change over time. PMID:19461530

  8. Bone cutting.

    PubMed

    Giraud, J Y; Villemin, S; Darmana, R; Cahuzac, J P; Autefage, A; Morucci, J P

    1991-02-01

    Bone cutting has always been a problem for surgeons because bone is a hard living material, and many osteotomes are still very crude tools. Technical improvement of these surgical tools has first been their motorization. Studies of the bone cutting process have indicated better features for conventional tools. Several non-conventional osteotomes, particularly ultrasonic osteotomes are described. Some studies on the possible use of lasers for bone cutting are also reported. Use of a pressurised water jet is also briefly examined. Despite their advantages, non-conventional tools still require improvement if they are to be used by surgeons.

  9. Robust Optimization of a MEMS Accelerometer Considering Temperature Variations

    PubMed Central

    Liu, Guangjun; Yang, Feng; Bao, Xiaofan; Jiang, Tao

    2015-01-01

    A robust optimization approach for a MEMS accelerometer to minimize the effects of temperature variations is presented. The mathematical model of the accelerometer is built. The effects of temperature variations on the output performance of the accelerometer are determined, and thermal deformation of the accelerometer is analyzed. The deviations of the output capacitance and resonance frequency due to temperature fluctuations are calculated and discussed. The sensitivity analysis method is employed to determine the design variables for robust optimization and find out the key structural parameters that have most significant influence on the output capacitance and resonance frequency of the accelerometer. The mathematical model and procedure for the robust optimization of the accelerometer are proposed. The robust optimization problem is solved and discussed. The robust optimization results show that an optimized accelerometer with high sensitivity, high temperature robustness and decoupling structure is finally obtained. PMID:25785308

  10. Feasibility study of ZnO nanowire made accelerometer

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Chan; Ko, Hyun-U.; Song, Sangho; Yun, Youngmin; Kim, Jaehwan

    2016-04-01

    Vertically aligned arrays of ZnO nanowire can be used for many applications such as energy harvesters, UV sensors and mechanical sensors. Here we report the feasibility of a miniaturized accelerometer made with ZnO nanowire. For improving the sensitivity of miniaturized piezoelectric accelerometer, size of piezoelectric ceramic should be large which results in heavy accelerometer and low resonance frequency. To resolve the problem for the miniaturized accelerometer fabrication, ZnO nanowire is chosen. ZnO nanowire, which has piezoelectric property with Wurtzite structure. Since it has high aspect ratio, the use of ZnO nanowire leads to increase deformation and piezoelectric response output. The vertically ZnO nanowire array is grown on a copper substrate by hydrothermal synthesis process. Detail Fabrication process of the miniaturized accelerometer is illustrated. To prove the feasibility of the fabricated accelerometer, dynamic response test is performed in comparison with a commercial accelerometer.

  11. MGRA: Motion Gesture Recognition via Accelerometer.

    PubMed

    Hong, Feng; You, Shujuan; Wei, Meiyu; Zhang, Yongtuo; Guo, Zhongwen

    2016-04-13

    Accelerometers have been widely embedded in most current mobile devices, enabling easy and intuitive operations. This paper proposes a Motion Gesture Recognition system (MGRA) based on accelerometer data only, which is entirely implemented on mobile devices and can provide users with real-time interactions. A robust and unique feature set is enumerated through the time domain, the frequency domain and singular value decomposition analysis using our motion gesture set containing 11,110 traces. The best feature vector for classification is selected, taking both static and mobile scenarios into consideration. MGRA exploits support vector machine as the classifier with the best feature vector. Evaluations confirm that MGRA can accommodate a broad set of gesture variations within each class, including execution time, amplitude and non-gestural movement. Extensive evaluations confirm that MGRA achieves higher accuracy under both static and mobile scenarios and costs less computation time and energy on an LG Nexus 5 than previous methods.

  12. Multi-Axis Accelerometer Calibration System

    NASA Technical Reports Server (NTRS)

    Finley, Tom; Parker, Peter

    2010-01-01

    A low-cost, portable, and simplified system has been developed that is suitable for in-situ calibration and/or evaluation of multi-axis inertial measurement instruments. This system overcomes facility restrictions and maintains or improves the calibration quality for users of accelerometer-based instruments with applications in avionics, experimental wind tunnel research, and force balance calibration applications. The apparatus quickly and easily positions a multi-axis accelerometer system into a precisely known orientation suitable for in-situ quality checks and calibration. In addition, the system incorporates powerful and sophisticated statistical methods, known as response surface methodology and statistical quality control. These methods improve calibration quality, reduce calibration time, and allow for increased calibration frequency, which enables the monitoring of instrument stability over time.

  13. Dark matter direct detection with accelerometers

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Kaplan, David E.; Mardon, Jeremy; Rajendran, Surjeet; Terrano, William A.

    2016-04-01

    The mass of the dark matter particle is unknown, and may be as low as ˜1 0-22 eV . The lighter part of this range, below ˜eV , is relatively unexplored both theoretically and experimentally but contains an array of natural dark matter candidates. An example is the relaxion, a light boson predicted by cosmological solutions to the hierarchy problem. One of the few generic signals such light dark matter can produce is a time-oscillating, equivalence-principle-violating force. We propose searches for this using accelerometers, and consider in detail the examples of torsion balances, atom interferometry, and pulsar timing. These approaches have the potential to probe large parts of unexplored parameter space in the next several years. Thus such accelerometers provide radically new avenues for the direct detection of dark matter.

  14. MGRA: Motion Gesture Recognition via Accelerometer

    PubMed Central

    Hong, Feng; You, Shujuan; Wei, Meiyu; Zhang, Yongtuo; Guo, Zhongwen

    2016-01-01

    Accelerometers have been widely embedded in most current mobile devices, enabling easy and intuitive operations. This paper proposes a Motion Gesture Recognition system (MGRA) based on accelerometer data only, which is entirely implemented on mobile devices and can provide users with real-time interactions. A robust and unique feature set is enumerated through the time domain, the frequency domain and singular value decomposition analysis using our motion gesture set containing 11,110 traces. The best feature vector for classification is selected, taking both static and mobile scenarios into consideration. MGRA exploits support vector machine as the classifier with the best feature vector. Evaluations confirm that MGRA can accommodate a broad set of gesture variations within each class, including execution time, amplitude and non-gestural movement. Extensive evaluations confirm that MGRA achieves higher accuracy under both static and mobile scenarios and costs less computation time and energy on an LG Nexus 5 than previous methods. PMID:27089336

  15. A very low noise monolithic Horizontal accelerometer.

    NASA Astrophysics Data System (ADS)

    Bertolini, Alessandro; Takamori, Akiteru; Cella, Giancarlo; Fidecaro, Francesco; Francesconi, Mario; Desalvo, Riccardo; Sannibale, Virginio

    2000-04-01

    We present a new low noise, low frequency, horizontal accelerometer. The mechanical design and the machining process aim to improve the sensitivity in the frequency region between 0.01 and 1 Hz, where metal internal friction and thermal elastic effects become critical. The accelerometer mechanics is shaped as a small folded pendulum in order to obtain a very low resonant frequency and low mechanical losses. A folded pendulum is essentially a mass suspended on one side by a simple pendulum and on the other by an inverted pendulum working antagonistically. The straight pendulum positive gravitational spring constant is balanced by the inverted pendulum’s negative one; by changing the center of mass position one can lower arbitrarily the resonant frequency. The only dissipation is in the anelasticity of the mechanical flex joint and in the readout/actuation system. If the spring constant is minimised, the mechanical losses are minimal. The monolithic design of the accelerometer eliminates the stick-and-slip friction localised in the flexure clamps. Low stiffness, 10 micron thick flex joints are achieved by EDM and electropolishing. The instrument is equipped with a low capacitance position sensor; the signal from the sensor is filtered by a PID controller and fed back to the mass through capacitive force actuator for feedback closed-loop operation. The sensor noise matches the expected thermal noise performances, 10-12 m/√Hz , with measuring range of a few microns. The expected sensitivity, less than 10-11 m/ s^2 / √Hz around 150 mHz, is a factor 30 below the state of the art limit. This accelerometer was designed to be integrated in the active control of the LIGO II mirror seismic isolators.

  16. The GRADIO accelerometer - Design and development status

    NASA Astrophysics Data System (ADS)

    Bernard, A.; Touboul, P.

    The concept of Satellite Gravity Gradiometry based on differential microaccelerometry has been proposed by ONERA in the early eighties. Since 1986, an important effort is devoted to the development of the GRADIO accelerometers. Their configuration has been optimized for the ARISTOTELES mission with the objective of 0.01 Eotvos resolution for an integrating time of 4 s. The achieved resolution, better than 10 exp -9 G, is limited by the actual stability of alignments on the testing equipment.

  17. A novel differential optical fiber accelerometer

    NASA Astrophysics Data System (ADS)

    Pi, Shaohua; Zhao, Jiang; Hong, Guangwei; Jia, Bo

    2013-08-01

    The development of sensitive fiber-optic accelerometers is a subject of continuing interest. To acquire high resolution, Michelson phase interferometric techniques are widely adopted. Among the variety structures, the compliant cylinder approach is particularly attractive due to its high sensitivity that is defined as the induced phase shift per applied acceleration. While the two arms of Michelson interferometer should be at the same optical path, it is inconvenient to adjust the two arms' length to equal, also the polarization instability and phase random drift will cause a signal decline. To overcome these limitations, a novel optical fiber accelerometer based on differential interferometric techniques is proposed and investigated. The interferometer is a Sagnac-like white light interferometer, which means the bandwidth of laser spectrum can be as wide as tens nanometers. This interferometer was firstly reported by Levin in 1990s. Lights are divided to two paths before entering the coupler. To induce time difference, one passes through a delay arm and another goes a direct arm. After modulated by the sensing component, they reflect to opposite arm. The sensing part is formed by a seismic mass that is held to only one compliant cylinder, where the single-mode optical fiber is wrapped tightly. When sticking to vibrations, the cylinder compresses or stretches as a spring. The corresponding changes in cylinder circumference lead to strain in the sensing fibers, which is detected as an optical phase shift by the interferometer. The lights from two arms reach the vibration source at different time, sensing a different accelerate speed; produce a different optic path difference. Integrating the dissimilarity of the accelerated speed by time can obtain the total acceleration graph. A shaker's vibration has been tested by the proposed accelerometer referring to a standard piezoelectric accelerometer. A 99.8% linearity of the optical phase shift to the ground acceleration

  18. High performance MEMS accelerometers for concrete SHM applications and comparison with COTS accelerometers

    NASA Astrophysics Data System (ADS)

    Kavitha, S.; Joseph Daniel, R.; Sumangala, K.

    2016-01-01

    Accelerometers used for civil and huge mechanical structural health monitoring intend to measure the shift in the natural frequency of the monitored structures (<100 Hz) and such sensors should have large sensitivity and extremely low noise floor. Sensitivity of accelerometers is inversely proportional to the frequency squared. Commercial MEMS (Micro Electro-Mechanical System) accelerometers that are generally designed for large bandwidth (e.g 25 kHz in ADXL150) have poor sensor level sensitivity and therefore uses complex signal conditioning electronics to achieve large sensitivity and low noise floor which in turn results in higher cost. In this work, an attempt has been made to design MEMS capacitive and piezoresistive accelerometers for smaller bandwidth using IntelliSuite and CoventorWare MEMS tools respectively. The various performance metrics have been obtained using simulation experiments and the results show that these sensors have excellent voltage sensitivity, noise performance and high resolution at sensor level and are even superior to commercial MEMS accelerometers.

  19. Accelerometer Data Analysis and Presentation Techniques

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.; Hrovat, Kenneth; McPherson, Kevin; Moskowitz, Milton E.; Reckart, Timothy

    1997-01-01

    The NASA Lewis Research Center's Principal Investigator Microgravity Services project analyzes Orbital Acceleration Research Experiment and Space Acceleration Measurement System data for principal investigators of microgravity experiments. Principal investigators need a thorough understanding of data analysis techniques so that they can request appropriate analyses to best interpret accelerometer data. Accelerometer data sampling and filtering is introduced along with the related topics of resolution and aliasing. Specific information about the Orbital Acceleration Research Experiment and Space Acceleration Measurement System data sampling and filtering is given. Time domain data analysis techniques are discussed and example environment interpretations are made using plots of acceleration versus time, interval average acceleration versus time, interval root-mean-square acceleration versus time, trimmean acceleration versus time, quasi-steady three dimensional histograms, and prediction of quasi-steady levels at different locations. An introduction to Fourier transform theory and windowing is provided along with specific analysis techniques and data interpretations. The frequency domain analyses discussed are power spectral density versus frequency, cumulative root-mean-square acceleration versus frequency, root-mean-square acceleration versus frequency, one-third octave band root-mean-square acceleration versus frequency, and power spectral density versus frequency versus time (spectrogram). Instructions for accessing NASA Lewis Research Center accelerometer data and related information using the internet are provided.

  20. A Flexure-Based Tool Holder for Sub-(micro)m Positioning of a Single Point Cutting Tool on a Four-axis Lathe

    SciTech Connect

    Bono, M J; Hibbard, R L

    2005-12-05

    A tool holder was designed to facilitate the machining of precision meso-scale components with complex three-dimensional shapes with sub-{micro}m accuracy on a four-axis lathe. A four-axis lathe incorporates a rotary table that allows the cutting tool to swivel with respect to the workpiece to enable the machining of complex workpiece forms, and accurately machining complex meso-scale parts often requires that the cutting tool be aligned precisely along the axis of rotation of the rotary table. The tool holder designed in this study has greatly simplified the process of setting the tool in the correct location with sub-{micro}m precision. The tool holder adjusts the tool position using flexures that were designed using finite element analyses. Two flexures adjust the lateral position of the tool to align the center of the nose of the tool with the axis of rotation of the B-axis, and another flexure adjusts the height of the tool. The flexures are driven by manual micrometer adjusters, each of which provides a minimum increment of motion of 20 nm. This tool holder has simplified the process of setting a tool with sub-{micro}m accuracy, and it has significantly reduced the time required to set a tool.

  1. Cutting Head for Ultrasonic Lithotripsy

    NASA Technical Reports Server (NTRS)

    Angulo, Earl D. (Inventor); Goodfriend, Roger (Inventor)

    1989-01-01

    A cutting head for attachment to the end of the wire probe of an ultrasonic kidney stone disintegration instrument. The cutting head has a plurality of circumferentially arranged teeth formed at one end thereof to provide a cup-shaped receptacle for kidney stones encountered during the disintegration procedure. An integral reduced diameter collar diminishes stress points in the wire and reduces breakage thereof.

  2. Specific cut-off points for waist circumference and waist-to-height ratio as predictors of cardiometabolic risk in Black subjects: a cross-sectional study in Benin and Haiti

    PubMed Central

    EL Mabchour, Asma; Delisle, Hélène; Vilgrain, Colette; Larco, Philippe; Sodjinou, Roger; Batal, Malek

    2015-01-01

    Purpose Waist circumference (WC) and waist-to-height ratio (WHtR) are widely used as indicators of abdominal adiposity and the cut-off values have been validated primarily in Caucasians. In this study we identified the WC and WHtR cut-off points that best predicted cardiometabolic risk (CMR) in groups of African (Benin) and African ancestry (Haiti) Black subjects. Methods This cross-sectional study included 452 apparently healthy subjects from Cotonou (Benin) and Port-au-Prince (Haiti), 217 women and 235 men from 25 to 60 years. CMR biomarkers were the metabolic syndrome components. Additional CMR biomarkers were a high atherogenicity index (total serum cholesterol/high density lipoprotein cholesterol ≥4 in women and ≥5 in men); insulin resistance set at the 75th percentile of the calculated Homeostasis Model Assessment index (HOMA-IR); and inflammation defined as high-sensitivity C-reactive protein (hsCRP) concentrations between 3 and 10 mg/L. WC and WHtR were tested as predictors of two out of the three most prevalent CMR biomarkers. Receiver operating characteristic (ROC) curves, Youden’s index, and likelihood ratios were used to assess the performance of specific WC and WHtR cut-offs. Results High atherogenicity index (59.5%), high blood pressure (23.2%), and insulin resistance (25% by definition) were the most prevalent CMR biomarkers in the study groups. WC and WHtR were equally valid as predictors of CMR. Optimal WC cut-offs were 80 cm and 94 cm in men and women, respectively, which is exactly the reverse of the generic cut-offs. The standard 0.50 cut-off of WHtR appeared valid for men, but it had to be increased to 0.59 in women. Conclusion CMR was widespread in these population groups. The present study suggests that in order to identify Africans with high CMR, WC thresholds will have to be increased in women and lowered in men. Data on larger samples are needed. PMID:26604808

  3. Accelerometer Use in a Physical Activity Intervention Trial

    PubMed Central

    Borradaile, Kelley E.; Lewis, Beth A.; Whiteley, Jessica A.; Longval, Jaime L.; Parisi, Alfred F.; Albrecht, Anna E.; Sciamanna, Christopher N.; Jakicic, John M.; Papandonatos, George D.; Marcus, Bess H.

    2010-01-01

    This paper describes the application of best practice recommendations for using accelerometers in a physical activity (PA) intervention trial, and the concordance of different methods for measuring PA. A subsample (n=63; 26%) of the 239 healthy, sedentary adults participating in a PA trial (mean age=47.5; 82% women) wore the ActiGraph monitor at all 3 assessment time points. ActiGraph data were compared with self-report (i.e., PA weekly recall and monthly log) and fitness variables. Correlations between the PA recall and ActiGraph for moderate intensity activity ranged from 0.16–0.48 and from 0.28–0.42 for vigorous intensity activity. ActiGraph and fitness [estimated VO2(ml/kg/min)] had correlations of 0.15–0.45. The ActiGraph and weekly self-report were significantly correlated at all time points (correlations ranged from 0.23–0.44). In terms of detecting intervention effects, intervention groups recorded more minutes of at least moderate-intensity PA on the ActiGraph than the control group at 6 months (min=46.47, 95% CI=14.36–78.58), but not at 12 months. Limitations of the study include a small sample size and only 3 days of ActiGraph monitoring. To obtain optimal results with accelerometers in clinical trials, the authors recommend following best practice recommendations: detailed protocols for monitor use, calibration of monitors and validation of data quality, and use of validated equations for analysis. The ActiGraph has modest concordance with other assessment tools and is sensitive to change over time. However, until more information validating the use of accelerometry in clinical trials becomes available, properly administered self-report measures of PA should remain part of the assessment battery. PMID:20723619

  4. Accelerometer use in a physical activity intervention trial.

    PubMed

    Napolitano, Melissa A; Borradaile, Kelley E; Lewis, Beth A; Whiteley, Jessica A; Longval, Jaime L; Parisi, Alfred F; Albrecht, Anna E; Sciamanna, Christopher N; Jakicic, John M; Papandonatos, George D; Marcus, Bess H

    2010-11-01

    This paper describes the application of best practice recommendations for using accelerometers in a physical activity (PA) intervention trial, and the concordance of different methods for measuring PA. A subsample (n = 63; 26%) of the 239 healthy, sedentary adults participating in a PA trial (mean age = 47.5; 82% women) wore the ActiGraph monitor at all 3 assessment time points. ActiGraph data were compared with self-report (i.e., PA weekly recall and monthly log) and fitness variables. Correlations between the PA recall and ActiGraph for moderate intensity activity ranged from 0.16-0.48 and from 0.28-0.42 for vigorous intensity activity. ActiGraph and fitness [estimated VO(2)(ml/kg/min)] had correlations of 0.15-0.45. The ActiGraph and weekly self-report were significantly correlated at all time points (correlations ranged from 0.23 to 0.44). In terms of detecting intervention effects, intervention groups recorded more minutes of at least moderate-intensity PA on the ActiGraph than the control group at 6 months (min = 46.47, 95% CI = 14.36-78.58), but not at 12 months. Limitations of the study include a small sample size and only 3 days of ActiGraph monitoring. To obtain optimal results with accelerometers in clinical trials, the authors recommend following best practice recommendations: detailed protocols for monitor use, calibration of monitors and validation of data quality, and use of validated equations for analysis. The ActiGraph has modest concordance with other assessment tools and is sensitive to change over time. However, until more information validating the use of accelerometry in clinical trials becomes available, properly administered self-report measures of PA should remain part of the assessment battery.

  5. A biomimetic accelerometer inspired by the cricket's clavate hair.

    PubMed

    Droogendijk, H; de Boer, M J; Sanders, R G P; Krijnen, G J M

    2014-08-06

    Crickets use so-called clavate hairs to sense (gravitational) acceleration to obtain information on their orientation. Inspired by this clavate hair system, a one-axis biomimetic accelerometer has been developed and fabricated using surface micromachining and SU-8 lithography. An analytical model is presented for the design of the accelerometer, and guidelines are derived to reduce responsivity due to flow-induced contributions to the accelerometer's output. Measurements show that this microelectromechanical systems (MEMS) hair-based accelerometer has a resonance frequency of 320 Hz, a detection threshold of 0.10 ms(-2) and a dynamic range of more than 35 dB. The accelerometer exhibits a clear directional response to external accelerations and a low responsivity to airflow. Further, the accelerometer's physical limits with respect to noise levels are addressed and the possibility for short-term adaptation of the sensor to the environment is discussed.

  6. Comparison and validation of capacitive accelerometers for health care applications.

    PubMed

    Büsching, Felix; Kulau, Ulf; Gietzelt, Matthias; Wolf, Lars

    2012-05-01

    Fall detection, gait analysis and context recognition are examples of applications where capacitive accelerometers are widely used in health care. In most of the existing work, algorithms were developed for a specific platform and accelerometers were used without explicitly choosing a specific type. With this work we present an inexpensive and practical test setup for replicable and repeatable testing of accelerometers. In addition we use this setup to evaluate six of the most commonly available accelerometers today and list their outcomes for linearity, power consumption and correlation of the tested sensors. We also attempt to an answer to the question of whether applications and algorithms developed for one platform and one type of accelerometer can be easily transferred to another accelerometer.

  7. A new accelerometer recording system for shuttle use

    NASA Technical Reports Server (NTRS)

    Lichtenberg, Byron

    1990-01-01

    Microgravity investigators are interested in enhancing the capabilities and improving the information return from accelerometers used in microgravity research. In addition to improving the accelerometer sensor, efforts should be directed towards using recent advances in microprocessor technology and system design techniques to improve sensor calibration and temperature compensation, online data display and analysis, and data reduction and information storage. Results from the above areas of investigation should be combined in an integrated design for a spaceflight microgravity accelerometer package.

  8. Design and Implementation of a Micromechanical Silicon Resonant Accelerometer

    PubMed Central

    Huang, Libin; Yang, Hui; Gao, Yang; Zhao, Liye; Liang, Jinxing

    2013-01-01

    The micromechanical silicon resonant accelerometer has attracted considerable attention in the research and development of high-precision MEMS accelerometers because of its output of quasi-digital signals, high sensitivity, high resolution, wide dynamic range, anti-interference capacity and good stability. Because of the mismatching thermal expansion coefficients of silicon and glass, the micromechanical silicon resonant accelerometer based on the Silicon on Glass (SOG) technique is deeply affected by the temperature during the fabrication, packaging and use processes. The thermal stress caused by temperature changes directly affects the frequency output of the accelerometer. Based on the working principle of the micromechanical resonant accelerometer, a special accelerometer structure that reduces the temperature influence on the accelerometer is designed. The accelerometer can greatly reduce the thermal stress caused by high temperatures in the process of fabrication and packaging. Currently, the closed-loop drive circuit is devised based on a phase-locked loop. The unloaded resonant frequencies of the prototype of the micromechanical silicon resonant accelerometer are approximately 31.4 kHz and 31.5 kHz. The scale factor is 66.24003 Hz/g. The scale factor stability is 14.886 ppm, the scale factor repeatability is 23 ppm, the bias stability is 23 μg, the bias repeatability is 170 μg, and the bias temperature coefficient is 0.0734 Hz/°C. PMID:24256978

  9. Suitability of MEMS Accelerometers for Condition Monitoring: An experimental study

    PubMed Central

    Albarbar, Alhussein; Mekid, Samir; Starr, Andrew; Pietruszkiewicz, Robert

    2008-01-01

    With increasing demands for wireless sensing nodes for assets control and condition monitoring; needs for alternatives to expensive conventional accelerometers in vibration measurements have been arisen. Micro-Electro Mechanical Systems (MEMS) accelerometer is one of the available options. The performances of three of the MEMS accelerometers from different manufacturers are investigated in this paper and compared to a well calibrated commercial accelerometer used as a reference for MEMS sensors performance evaluation. Tests were performed on a real CNC machine in a typical industrial environmental workshop and the achieved results are presented. PMID:27879734

  10. Suitability of MEMS Accelerometers for Condition Monitoring: An experimental study.

    PubMed

    Albarbar, Alhussein; Mekid, Samir; Starr, Andrew; Pietruszkiewicz, Robert

    2008-02-06

    With increasing demands for wireless sensing nodes for assets control and condition monitoring; needs for alternatives to expensive conventional accelerometers in vibration measurements have been arisen. Micro-Electro Mechanical Systems (MEMS) accelerometer is one of the available options. The performances of three of the MEMS accelerometers from different manufacturers are investigated in this paper and compared to a well calibrated commercial accelerometer used as a reference for MEMS sensors performance evaluation. Tests were performed on a real CNC machine in a typical industrial environmental workshop and the achieved results are presented.

  11. A three-axis ultrasensitive accelerometer for space

    NASA Astrophysics Data System (ADS)

    Bernard, A.

    A three-axis ultrasensitive accelerometer ASTRE (Accelerometre Spatial Triaxial Electrostatique) is a simplified version of the GRADIO accelerometer designed for the ARISTOTELES mission, which operates by measuring the force provided by a three-axis electrostatic suspension of the proof-mass. It covers the g-spectrum from 10 exp -8 to 10 exp -4 in the frequency range dc to 5 Hz. A dedicated test bench was developed in order to preserve the accelerometer from the seismic noise. The paper presents the performance parameters of the ASTRE accelerometer and some of the design schemes.

  12. The GRADIO accelerometer: Design and development status

    NASA Astrophysics Data System (ADS)

    Bernard, Alain; Touboul, M. P.

    1991-12-01

    The concept of Satellite Gravity Gradiometry (SGG) based on differential microaccelerometry as proposed in the early eighties is summarized. Work devoted to the development of the GRADIO accelerometers is described. The configuration was optimized for the Aristoteles mission with the objective of increasing resolution for an integrating time of 4 s. Thanks to the selected three axis configuration, very sensitive differential tests were carried out between two very representative laboratory models, in directions perpendicular to gravity. The resolution of these tests, limited by the actual stability of alignments of the testing equipment is described.

  13. A comprehensive evaluation of commonly used accelerometer energy expenditure and MET prediction equations.

    PubMed

    Lyden, Kate; Kozey, Sarah L; Staudenmeyer, John W; Freedson, Patty S

    2011-02-01

    Numerous accelerometers and prediction methods are used to estimate energy expenditure (EE). Validation studies have been limited to small sample sizes in which participants complete a narrow range of activities and typically validate only one or two prediction models for one particular accelerometer. The purpose of this study was to evaluate the validity of nine published and two proprietary EE prediction equations for three different accelerometers. Two hundred and seventy-seven participants completed an average of six treadmill (TRD) (1.34, 1.56, 2.23 ms(-1) each at 0 and 3% grade) and five self-paced activities of daily living (ADLs). EE estimates were compared with indirect calorimetry. Accelerometers were worn while EE was measured using a portable metabolic unit. To estimate EE, 4 ActiGraph prediction models were used, 5 Actical models, and 2 RT3 proprietary models. Across all activities, each equation underestimated EE (bias -0.1 to -1.4 METs and -0.5 to -1.3 kcal, respectively). For ADLs EE was underestimated by all prediction models (bias -0.2 to -2.0 and -0.2 to -2.8, respectively), while TRD activities were underestimated by seven equations, and overestimated by four equations (bias -0.8 to 0.2 METs and -0.4 to 0.5 kcal, respectively). Misclassification rates ranged from 21.7 (95% CI 20.4, 24.2%) to 34.3% (95% CI 32.3, 36.3%), with vigorous intensity activities being most often misclassified. Prediction equations did not yield accurate point estimates of EE across a broad range of activities nor were they accurate at classifying activities across a range of intensities (light <3 METs, moderate 3-5.99 METs, vigorous ≥ 6 METs). Current prediction techniques have many limitations when translating accelerometer counts to EE.

  14. Alternative Metal Hot Cutting Operations for Opacity

    DTIC Science & Technology

    2014-10-01

    Distribution A: Approved for public release; distribution is unlimited. TDS-NAVFAC-EXWC-EV-1509 October 2014 Alternative Metal Hot Cutting...demonstration (see Figure 1) and validation. Figure 1: Demonstration of alternative gasified hot - cutting fuel. PROPOSED BENEFITS 1...1205, March 2012. Alternative Metal Hot Cutting Operations for Opacity, TR-NAVFAC-EXWC-EV-1409, November 2014. POINTS OF CONTACT To acquire

  15. Calibrating Accelerometers Using an Electromagnetic Launcher

    SciTech Connect

    Erik Timpson

    2012-05-13

    A Pulse Forming Network (PFN), Helical Electromagnetic Launcher (HEML), Command Module (CM), and Calibration Table (CT) were built and evaluated for the combined ability to calibrate an accelerometer. The PFN has a maximum stored energy of 19.25 kJ bank and is fired by a silicon controlled rectifier (SCR), with appropriate safety precautions. The HEML is constructed out of G-10 fiberglass and is designed to accelerate 600 grams to 10 meters per second. The CM is microcontroller based running Arduino Software. The CM has a keypad input and 7 segment outputs of the bank voltage and desired voltage. After entering a desired bank voltage, the CM controls the charge of the PFN. When the two voltages are equal it allows the fire button to send a pulse to the SCR to fire the PFN and in turn, the HEML. The HEML projectile's tip hits a target that is held by the CT. The CT consists of a table to hold the PFN and HEML, a vacuum chuck, air bearing, velocity meter and catch pot. The Target is held with the vacuum chuck awaiting impact. After impact, the air bearing allows the target to fall freely for the velocity meter to get an accurate reading. A known acceleration is determined from the known change in velocity of the target. Thus, if an accelerometer was attached to the target, the measured value can be compared to the known value.

  16. Classification of Sporting Activities Using Smartphone Accelerometers

    PubMed Central

    Mitchell, Edmond; Monaghan, David; O'Connor, Noel E.

    2013-01-01

    In this paper we present a framework that allows for the automatic identification of sporting activities using commonly available smartphones. We extract discriminative informational features from smartphone accelerometers using the Discrete Wavelet Transform (DWT). Despite the poor quality of their accelerometers, smartphones were used as capture devices due to their prevalence in today's society. Successful classification on this basis potentially makes the technology accessible to both elite and non-elite athletes. Extracted features are used to train different categories of classifiers. No one classifier family has a reportable direct advantage in activity classification problems to date; thus we examine classifiers from each of the most widely used classifier families. We investigate three classification approaches; a commonly used SVM-based approach, an optimized classification model and a fusion of classifiers. We also investigate the effect of changing several of the DWT input parameters, including mother wavelets, window lengths and DWT decomposition levels. During the course of this work we created a challenging sports activity analysis dataset, comprised of soccer and field-hockey activities. The average maximum F-measure accuracy of 87% was achieved using a fusion of classifiers, which was 6% better than a single classifier model and 23% better than a standard SVM approach. PMID:23604031

  17. Validation of cardiac accelerometer sensor measurements.

    PubMed

    Remme, Espen W; Hoff, Lars; Halvorsen, Per Steinar; Naerum, Edvard; Skulstad, Helge; Fleischer, Lars A; Elle, Ole Jakob; Fosse, Erik

    2009-12-01

    In this study we have investigated the accuracy of an accelerometer sensor designed for the measurement of cardiac motion and automatic detection of motion abnormalities caused by myocardial ischaemia. The accelerometer, attached to the left ventricular wall, changed its orientation relative to the direction of gravity during the cardiac cycle. This caused a varying gravity component in the measured acceleration signal that introduced an error in the calculation of myocardial motion. Circumferential displacement, velocity and rotation of the left ventricular apical region were calculated from the measured acceleration signal. We developed a mathematical method to separate translational and gravitational acceleration components based on a priori assumptions of myocardial motion. The accuracy of the measured motion was investigated by comparison with known motion of a robot arm programmed to move like the heart wall. The accuracy was also investigated in an animal study. The sensor measurements were compared with simultaneously recorded motion from a robot arm attached next to the sensor on the heart and with measured motion by echocardiography and a video camera. The developed compensation method for the varying gravity component improved the accuracy of the calculated velocity and displacement traces, giving very good agreement with the reference methods.

  18. Six Degree Freedom Optical Fiber Accelerometer

    NASA Astrophysics Data System (ADS)

    Cazo, Rogerio Moreira; dos Reis Ribeiro, Erik; Nunes, Marcelo Buonocore; Barbosa, Carmem Lucia; de Siqueira Ferreira, Jorge Luis; de Barros Caldas, Tales; dos Santos, Josemir Coelho; de Arruda, Josiel Urbaninho

    2008-10-01

    Linear accelerations measurements are needed in many applications, as industry, military, aircrafts, space navigation, robotics and others. Actually, the most usual solutions to measure linear accelerations are three piezoelectric sensors used in orthogonal mounting, or MEM's sensors chips. Angular accelerations also are interesting to control and stabilize structures, like satellites and servo motors. It is possible to measure angular accelerations in two ways: direct measurement (using special sensors), or indirect measurements (obtaining acceleration of the angular velocity information) [1]. This work intends to present the structural and optical requirements of a six degree freedom opto-mechanical accelerometer based on fiber Bragg grating (FBG). With this sensor, it will be possible the direct measurement of three axial accelerations, and of three angular accelerations, with unlimited rotation angle, using one single proof mass. The FBG's are used as strain sensors and sustaining elements of the proof mass in the structure. Simulations have demonstrated that cross influences of 10 parts per million at worst case are possible. This kind of accelerometer may be used in navigation control, structural monitoring, satellite stabilization, guidance control and harsh environments, for example. The project requirements include the wavelength of FBG's, pre-strain and length of active segment of optical fibers, dimensions, material and structure of inertial proof mass and position of the fibers in the sustaining structure

  19. A System for Monitoring Posture and Physical Activity Using Accelerometers

    DTIC Science & Technology

    2007-11-02

    Abstract- Accelerometers can be used to monitor physical activity in the home over prolonged periods. We describe a novel system for...processing schema in which these parameters are extracted is described. Keywords - physical activity , accelerometers, congestive heart failure, chronic...When monitoring the condition of patients with neurodegenerative or chronic diseases, a knowledge of their body movement and physical activity

  20. Identification of Accelerometer Nonwear Time and Sedentary Behavior

    ERIC Educational Resources Information Center

    Oliver, Melody; Badland, Hannah M.; Schofield, Grant M.; Shepherd, Janine

    2011-01-01

    The primary aim of the current study was to investigate the accuracy of various automated rules for determining accelerometer nonwear time in a sample of predominantly desk-based office workers (using their self-reported nonwear times as a criterion). Second, the authors examined the effect of applying these rules to accelerometer data retention…

  1. Validation of a wireless accelerometer network for energy expenditure measurement.

    PubMed

    Montoye, Alexander H K; Dong, Bo; Biswas, Subir; Pfeiffer, Karin A

    2016-11-01

    The purpose of this study was to validate a wireless network of accelerometers and compare it to a hip-mounted accelerometer for predicting energy expenditure in a semi-structured environment. Adults (n = 25) aged 18-30 engaged in 14 sedentary, ambulatory, exercise, and lifestyle activities over a 60-min protocol while wearing a portable metabolic analyser, hip-mounted accelerometer, and wireless network of three accelerometers worn on the right wrist, thigh, and ankle. Participants chose the order and duration of activities. Artificial neural networks were created separately for the wireless network and hip accelerometer for energy expenditure prediction. The wireless network had higher correlations (r = 0.79 vs. r = 0.72, P < 0.01) but similar root mean square error (2.16 vs. 2.09 METs, P > 0.05) to the hip accelerometer. Measured (from metabolic analyser) and predicted energy expenditure from the hip accelerometer were significantly different for the 3 of the 14 activities (lying down, sweeping, and cycle fast); conversely, measured and predicted energy expenditure from the wireless network were not significantly different for any activity. In conclusion, the wireless network yielded a small improvement over the hip accelerometer, providing evidence that the wireless network can produce accurate estimates of energy expenditure in adults participating in a range of activities.

  2. Technical Reliability Assessment of the Actigraph GT1M Accelerometer

    ERIC Educational Resources Information Center

    Silva, Pedro; Mota, Jorge; Esliger, Dale; Welk, Gregory

    2010-01-01

    The purpose of this study was to determine the reliability of the Actigraph GT1M (Pensacola, FL, USA) accelerometer activity count and step functions. Fifty GT1M accelerometers were initialized to collect simultaneous acceleration counts and steps data using 15-sec epochs. All reliability testing was completed using a mechanical shaker plate to…

  3. High sensitivity optical waveguide accelerometer based on Fano resonance.

    PubMed

    Wan, Fenghua; Qian, Guang; Li, Ruozhou; Tang, Jie; Zhang, Tong

    2016-08-20

    An optical waveguide accelerometer based on tunable asymmetrical Fano resonance in a ring-resonator-coupled Mach-Zehnder interferometer (MZI) is proposed and analyzed. A Fano resonance accelerometer has a relatively large workspace of coupling coefficients with high sensitivity, which has potential application in inertial navigation, missile guidance, and attitude control of satellites. Due to the interference between a high-Q resonance pathway and a coherent background pathway, a steep asymmetric line shape is generated, which greatly improves the sensitivity of this accelerometer. The sensitivity of the accelerometer is about 111.75 mW/g. A 393-fold increase in sensitivity is achieved compared with a conventional MZI accelerometer and is approximately equal to the single ring structure.

  4. Assessing Stride Variables and Vertical Stiffness with GPS-Embedded Accelerometers: Preliminary Insights for the Monitoring of Neuromuscular Fatigue on the Field.

    PubMed

    Buchheit, Martin; Gray, Andrew; Morin, Jean-Benoit

    2015-12-01

    The aim of the present study was to examine the ability of a GPS-imbedded accelerometer to assess stride variables and vertical stiffness (K), which are directly related to neuromuscular fatigue during field-based high-intensity runs. The ability to detect stride imbalances was also examined. A team sport player performed a series of 30-s runs on an instrumented treadmill (6 runs at 10, 17 and 24 km·h(-1)) with or without his right ankle taped (aimed at creating a stride imbalance), while wearing on his back a commercially-available GPS unit with an embedded 100-Hz tri-axial accelerometer. Contact (CT) and flying (FT) time, and K were computed from both treadmill and accelerometers (Athletic Data Innovations) data. The agreement between treadmill (criterion measure) and accelerometer-derived data was examined. We also compared the ability of the different systems to detect the stride imbalance. Biases were small (CT and K) and moderate (FT). The typical error of the estimate was trivial (CT), small (K) and moderate (FT), with nearly perfect (CT and K) and large (FT) correlations for treadmill vs. accelerometer. The tape induced very large increase in the right - left foot ∆ in CT, FT and K measured by the treadmill. The tape effect on CT and K ∆ measured with the accelerometers were also very large, but of lower magnitude than with the treadmill. The tape effect on accelerometer-derived ∆ FT was unclear. Present data highlight the potential of a GPS-embedded accelerometer to assess CT and K during ground running. Key pointsGPS-embedded tri-axial accelerometers may be used to assess contact time and vertical stiffness during ground running.These preliminary results open new perspective for the field monitoring of neuromuscular fatigue and performance in run-based sports.

  5. Assessing Stride Variables and Vertical Stiffness with GPS-Embedded Accelerometers: Preliminary Insights for the Monitoring of Neuromuscular Fatigue on the Field

    PubMed Central

    Buchheit, Martin; Gray, Andrew; Morin, Jean-Benoit

    2015-01-01

    The aim of the present study was to examine the ability of a GPS-imbedded accelerometer to assess stride variables and vertical stiffness (K), which are directly related to neuromuscular fatigue during field-based high-intensity runs. The ability to detect stride imbalances was also examined. A team sport player performed a series of 30-s runs on an instrumented treadmill (6 runs at 10, 17 and 24 km·h-1) with or without his right ankle taped (aimed at creating a stride imbalance), while wearing on his back a commercially-available GPS unit with an embedded 100-Hz tri-axial accelerometer. Contact (CT) and flying (FT) time, and K were computed from both treadmill and accelerometers (Athletic Data Innovations) data. The agreement between treadmill (criterion measure) and accelerometer-derived data was examined. We also compared the ability of the different systems to detect the stride imbalance. Biases were small (CT and K) and moderate (FT). The typical error of the estimate was trivial (CT), small (K) and moderate (FT), with nearly perfect (CT and K) and large (FT) correlations for treadmill vs. accelerometer. The tape induced very large increase in the right - left foot ∆ in CT, FT and K measured by the treadmill. The tape effect on CT and K ∆ measured with the accelerometers were also very large, but of lower magnitude than with the treadmill. The tape effect on accelerometer-derived ∆ FT was unclear. Present data highlight the potential of a GPS-embedded accelerometer to assess CT and K during ground running. Key points GPS-embedded tri-axial accelerometers may be used to assess contact time and vertical stiffness during ground running. These preliminary results open new perspective for the field monitoring of neuromuscular fatigue and performance in run-based sports PMID:26664264

  6. Mars Reconnaissance Orbiter Accelerometer Experiment Results

    NASA Astrophysics Data System (ADS)

    Keating, G. M.; Bougher, S. W.; Theriot, M. E.; Zurek, R. W.; Blanchard, R. C.; Tolson, R. H.; Murphy, J. R.

    2007-05-01

    The Mars Reconnaissance Orbiter (MRO) launched on August 12, 2005, designed for aerobraking, achieved Mars Orbital Insertion (MOI), March 10, 2006. Atmospheric density decreases exponentially with increasing height. By small propulsive adjustments of the apoapsis orbital velocity, periapsis altitude is fine tuned to the density surface that safely used the atmosphere of Mars to aerobrake over 400 orbits. MRO periapsis precessed from the South Pole at 6pm LST to near the equator at 3am LST. Meanwhile, apoapsis was brought dramatically from 40,000km at MOI to 460 km at aerobraking completion (ABX) August 30, 2006. After ABX, a few small propulsive maneuvers established the Primary Science Orbit (PSO), which without aerobraking would have required an additional 400 kg of fuel. Each of the 400 plus aerobraking orbits provided a vertical structure and distribution of density, scale heights, and temperatures, along the orbital path, providing key in situ insight into various upper atmosphere (greater than 100 km) processes. One of the major questions for scientists studying Mars is: "Where did the water go?" Honeywell's substantially improved electronics package for its IMU (QA-2000 accelerometer, gyro, electronics) maximized accelerometer sensitivities at the requests of The George Washington University, JPL, and Lockheed Martin. The improved accelerometer sensitivities allowed density measurements to exceed 200km, at least 40 km higher than with Mars Odyssey (MO). This extended vertical structures from MRO into the neutral lower exosphere, a region where various processes may allow atmospheric gasses to escape. Over the eons, water may have been lost in both near the surface and in the upper atmosphere. Thus the water balance throughout the entire atmosphere from subsurface to exosphere may both be critical. Comparisons of data from Mars Global Surveyor (MGS), MO and MRO help characterize key temporal and spatial cycles including: winter polar warming, planetary scale

  7. First Cut

    NASA Technical Reports Server (NTRS)

    Morring, Frank, Jr.

    2005-01-01

    Lockheed Martin and a Northrop Grumman/Boeing team expect the Crew Exploration Vehicle proposals they submitted last week to change, given the new top-down push at NASA to close the gap between space shuttle retirement and launch of the new crew carrier. Still, delivery of the proposals gives a first glimpse of at least one of the concepts for a space shuttle replacement. Instead of the ballistic capsule approach put forward in some early CEV concept work, Lockheed Martin proposed a lifting body shape with a two-stage thermal protection system, coupled with a cylindrical mission module to give crews of four to six extra room on trips to the Moon, and a trans-Earth injection module (TEIM) for the return powered-at least in the first cut-by a couple of Pratt & Whitney RL10 rocket engines.

  8. Modeling of the vibrating beam accelerometer nonlinearities

    NASA Astrophysics Data System (ADS)

    Romanowski, P. A.; Knop, R. C.

    Successful modeling and processing of the output of a quartz Vibrating Beam Accelerometer (VBA), whose errors are inherently nonlinear with respect to input acceleration, are reported. The VBA output, with two signals that are frequencies of vibrating quartz beams, has inherent higher-order terms. In order to avoid vibration rectification errors, the signal output must be sampled at a rapid rate and the output must be reduced using a nonlinear model. The present model, with acceleration as a function of frequency, is derived by a least-squares process where the covariance matrix is obtained from simulated data. The system performance is found to be acceptable to strategic levels, and it is shown that a vibration rectification error of 400 micrograms/sq g can be reduced to 4 micrograms/sq g by using the processor electronics and a nonlinear model.

  9. Atmospheric Modeling Using Accelerometer Data During Mars Atmosphere and Volatile Evolution (MAVEN) Flight Operations

    NASA Technical Reports Server (NTRS)

    Tolson, Robert H.; Lugo, Rafael A.; Baird, Darren T.; Cianciolo, Alicia D.; Bougher, Stephen W.; Zurek, Richard M.

    2017-01-01

    The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is a NASA orbiter designed to explore the Mars upper atmosphere, typically from 140 to 160 km altitude. In addition to the nominal science mission, MAVEN has performed several Deep Dip campaigns in which the orbit's closest point of approach, also called periapsis, was lowered to an altitude range of 115 to 135 km. MAVEN accelerometer data were used during mission operations to estimate atmospheric parameters such as density, scale height, along-track gradients, and wave structures. Density and scale height estimates were compared against those obtained from the Mars Global Reference Atmospheric Model and used to aid the MAVEN navigation team in planning maneuvers to raise and lower periapsis during Deep Dip operations. This paper describes the processes used to reconstruct atmosphere parameters from accelerometers data and presents the results of their comparison to model and navigation-derived values.

  10. Validation study of Polar V800 accelerometer

    PubMed Central

    Hernández-Vicente, Adrián; De Cocker, Katrien; Garatachea, Nuria

    2016-01-01

    Background The correct quantification of physical activity (PA) and energy expenditure (EE) in daily life is an important target for researchers and professionals. The objective of this paper is to study the validity of the Polar V800 for the quantification of PA and the estimation of EE against the ActiGraph (ActiTrainer) in healthy young adults. Methods Eighteen Caucasian active people (50% women) aged between 19–23 years wore an ActiTrainer on the right hip and a Polar V800 on the preferred wrist during 7 days. Paired samples t-tests were used to analyze differences in outcomes between devices, and Pearson’s correlation coefficients to examine the correlation between outcomes. The agreement was studied using the Bland-Altman method. Also, the association between the difference and the magnitude of the measurement (heteroscedasticity) was examined. Sensitivity, specificity and area under the receiver operating characteristic curve (ROC-AUC value) were calculated to evaluate the ability of the devices to accurately define a person who fulfills the recommendation of 10,000 daily steps. Results The devices significantly differed from each other on all outcomes (P<0.05), except for Polar V800’s alerts vs. ActiTrainer’s 1 hour sedentary bouts (P=0.595) and Polar V800’s walking time vs. ActiTrainer’s lifestyle time (P=0.484). Heteroscedasticity analyses were significant for all outcomes, except for Kcal and sitting time. The ROC-AUC value was fair (0.781±0.048) and the sensitivity and specificity was 98% and 58%, respectively. Conclusions The Polar V800 accelerometer has a comparable validity to the accelerometer in free-living conditions, regarding “1 hour sedentary bouts” and “V800’s walking time vs. ActiTrainer’s lifestyle time” in young adults. PMID:27570772

  11. Cutting head for ultrasonic lithotripsy

    NASA Technical Reports Server (NTRS)

    Anguluo, E. D.; Goodfriend, R. (Inventor)

    1985-01-01

    A cutting head for attachment to the end of the wire probe of an ultrasonic kidney stone disintegration instrument is described. The cutting head has a plurality of circumferentially arranged teeth formed at one end thereof to provide a cup shaped receptacle for kidney stones encountered during the disintegration procedure. An integral reduced diameter collar diminishes stress points in the wire and reduce breakage thereof.

  12. Placement of Accelerometers for High Sensing Resolution in Micromanipulation

    PubMed Central

    Latt, W. T.; Tan, U-X.; Riviere, C. N.; Ang, W. T.

    2012-01-01

    High sensing resolution is required in sensing of surgical instrument motion in micromanipulation tasks. Accelerometers can be employed to sense physiological motion of the instrument during micromanipulation. Various configurations of accelerometer placement had been introduced in the past to sense motion of a rigid-body such as a surgical instrument. Placement (location and orientation) of accelerometers fixed in the instrument plays a significant role in achieving high sensing resolution. However, there is no literature or work on the effect of placement of accelerometers on sensing resolution. In this paper, an approach of placement of accelerometers within an available space to obtain highest possible sensing resolution in sensing of rigid-body motion in micromanipulation tasks is proposed. Superiority of the proposed placement approach is shown in sensing of a microsurgical instrument angular motion by comparing sensing resolutions achieved as a result of employing the configuration following the proposed approach and the existing configurations. Apart from achieving high sensing resolution, and design simplicity, the proposed placement approach also provides flexibility in placing accelerometers; hence it is especially useful in applications with limited available space to mount accelerometers. PMID:22423176

  13. Vibration sensing in smart machine rotors using internal MEMS accelerometers

    NASA Astrophysics Data System (ADS)

    Jiménez, Samuel; Cole, Matthew O. T.; Keogh, Patrick S.

    2016-09-01

    This paper presents a novel topology for enhanced vibration sensing in which wireless MEMS accelerometers embedded within a hollow rotor measure vibration in a synchronously rotating frame of reference. Theoretical relations between rotor-embedded accelerometer signals and the vibration of the rotor in an inertial reference frame are derived. It is thereby shown that functionality as a virtual stator-mounted displacement transducer can be achieved through appropriate signal processing. Experimental tests on a prototype rotor confirm that both magnitude and phase information of synchronous vibration can be measured directly without additional stator-mounted key-phasor sensors. Displacement amplitudes calculated from accelerometer signals will become erroneous at low rotational speeds due to accelerometer zero-g offsets, hence a corrective procedure is introduced. Impact tests are also undertaken to examine the ability of the internal accelerometers to measure transient vibration. A further capability is demonstrated, whereby the accelerometer signals are used to measure rotational speed of the rotor by analysing the signal component due to gravity. The study highlights the extended functionality afforded by internal accelerometers and demonstrates the feasibility of internal sensor topologies, which can provide improved observability of rotor vibration at externally inaccessible rotor locations.

  14. Self Diagnostic Accelerometer Testing on the C-17 Aircraft

    NASA Technical Reports Server (NTRS)

    Tokars, Roger P.; Lekki, John D.

    2013-01-01

    The self diagnostic accelerometer (SDA) developed by the NASA Glenn Research Center was tested for the first time in an aircraft engine environment as part of the Vehicle Integrated Propulsion Research (VIPR) program. The VIPR program includes testing multiple critical flight sensor technologies. One such sensor, the accelerometer, measures vibrations to detect faults in the engine. In order to rely upon the accelerometer, the health of the accelerometer must be ensured. The SDA is a sensor system designed to actively determine the accelerometer structural health and attachment condition, in addition to vibration measurements. The SDA uses a signal conditioning unit that sends an electrical chirp to the accelerometer and recognizes changes in the response due to changes in the accelerometer health and attachment condition. To demonstrate the SDAs flight worthiness and robustness, multiple SDAs were mounted and tested on a C-17 aircraft engine. The engine test conditions varied from engine off, to idle, to maximum power. The SDA attachment conditions were varied from fully tight to loose. The newly developed SDA health algorithm described herein uses cross correlation pattern recognition to discriminate a healthy from a faulty SDA. The VIPR test results demonstrate for the first.

  15. A Comparison of Accelerometer Accuracy in Older Adults.

    PubMed

    Phillips, Lorraine J; Petroski, Gregory F; Markis, Natalie E

    2015-01-01

    Older adults' gait disorders present challenges for accurate activity monitoring. The current study compared the accuracy of accelerometer-detected to hand-tallied steps in 50 residential care/assisted living residents. Participants completed two walking trials wearing a Fitbit® Tracker and waist-, wrist-, and ankle-mounted Actigraph GT1M. Agreement between accelerometer and observed counts was calculated using concordance correlation coefficients (CCC), accelerometer to observed count ratios, accelerometer and observed count differences, and Bland-Altman plots. Classification and Regression Tree analysis identified minimum gait speed thresholds to achieve accelerometer accuracy ≥0.80. Participants' mean age was 84.2 and gait speed was 0.64 m/s. All accelerometers underestimated true steps. Only the ankle-mounted GT1M demonstrated positive agreement with observed counts (CCC = 0.205). Thresholds for 0.80 accuracy were gait speeds ≥0.56 m/s for the Fitbit and gait speeds ≥0.71 m/s for the ankle-mounted GT1M. Gait speed and accelerometer placement affected activity monitor accuracy in older adults.

  16. Recent Results from CHAMP Tracking and Accelerometer Data Analysis

    NASA Technical Reports Server (NTRS)

    Luthcke, S. B.; Rowlands, D. D.; Lemoine, F. G.; Nerem, R. S.; Thompson, B.; Pavlis, E.; Williams, T. A.; Colombo, O. L.; Chao, Benjamin F. (Technical Monitor)

    2002-01-01

    The CHAMP mission's unique combination of sensors and orbit configuration will enable unprecedented improvements in modeling and understanding the Earth's static gravity field and its temporal variations. CHAMP is the first of two missions (GRACE to be launched in the early part of 02') that combine a new generation of Global Positioning System (GPS) receivers, a high precision three-axis accelerometer, and star cameras for the precision attitude determination. In order to isolate the gravity signal for science investigations, it is necessary to perform a detailed reduction and analysis of the GPS and Satellite Laser Ranging (SLR) tracking data in conjunction with the accelerometer and attitude data. Precision orbit determination based on the GPS and SLR tracking data will isolate the orbit perturbations, while the accelerometer data will be used to distinguish the non-gravitational forces from those due to the geopotential (static, and time varying). In preparation for the CHAMP and GRACE missions, extensive modifications have been made to NASA/GSFC's GEODYN orbit determination software to enable the simultaneous reduction of spacecraft tracking (e.g. GPS and SLR), three-axis accelerometer and precise attitude data. Several weeks of CHAMP tracking and accelerometer data have been analyzed and the results will be presented. Precision orbit determination analysis based on tracking data alone in addition to results based on the simultaneous reduction of tracking and accelerometer data will be discussed. Results from a calibration of the accelerometer will be presented along with the results from various orbit determination strategies.

  17. Predicting Human Movement with Multiple Accelerometers Using Movelets

    PubMed Central

    He, Bing; Bai, Jiawei; Zipunnikov, Vadim V.; Koster, Annemarie; Caserotti, Paolo; Lange-Maia, Brittney; Glynn, Nancy W.; Harris, Tamara B.; Crainiceanu, Ciprian M.

    2014-01-01

    Purpose The study aims were: 1) to develop transparent algorithms that use short segments of training data for predicting activity types; and 2) to compare prediction performance of proposed algorithms using single accelerometers and multiple accelerometers. Methods Sixteen participants (age, 80.6 yr (4.8 yr); BMI, 26.1 kg·m−2 (2.5 kg·m−2)) performed fifteen life-style activities in the laboratory, each wearing three accelerometers at the right hip, left and right wrists. Triaxial accelerometry data were collected at 80 Hz using Actigraph GT3X+. Prediction algorithms were developed, which, instead of extracting features, build activity specific dictionaries composed of short signal segments called movelets. Three alternative approaches were proposed to integrate the information from the multiple accelerometers. Results With at most several seconds of training data per activity, the prediction accuracy at the second-level temporal resolution was very high for lying, standing, normal/fast walking, and standing up from a chair (the median prediction accuracy ranged from 88.2% to 99.9% based on the single-accelerometer movelet approach). For these activities wrist-worn accelerometers performed almost as well as hip-worn accelerometers (the median difference in accuracy between wrist and hip ranged from −2.7% to 5.8%). Modest improvements in prediction accuracy were achieved by integrating information from multiple accelerometers. Discussion and conclusions It is possible to achieve high prediction accuracy at the secondlevel temporal resolution with very limited training data. To increase prediction accuracy from the simultaneous use of multiple accelerometers, a careful selection of integrative approaches is required. PMID:25134005

  18. The vertical accelerometer, a new instrument for air navigation

    NASA Technical Reports Server (NTRS)

    Laboccetta, Letterio

    1923-01-01

    This report endeavors to show the possibility of determining the rate of acceleration and the advantage of having such an accelerometer in addition to other aviation instruments. Most of the discussions concern balloons.

  19. Design and fabrication of wireless remotely readable MEMS accelerometers

    NASA Astrophysics Data System (ADS)

    Varadan, Vijay K.; Subramanian, Hareesh; Varadan, Vasundara V.

    1997-11-01

    The integration of MEMS, SAW devices and required microelectronics and conformal antenna to realize a programmable wireless accelerometer is presented in this paper. This unique combination of technologies results in a novel accelerometer that can be remotely sensed by a microwave system with the advantage of no power requirements at the sensor site. The microaccelerometer presented is simple in construction and easy to manufacture with existing silicon micromachining techniques. The relatively small size of the sensor makes it an ideal conformal sensor. The accelerometer finds application as air bag deployment sensors, vibration sensors for noise control, deflection and strain sensors, inertial and dimensional positioning systems, ABS/traction control, smart suspension, active roll stabilization and four wheel steering. The wireless accelerometer is very attractive to study the response of a 'dummy' in automobile crash test.

  20. Wireless accelerometer iPod application for quantifying gait characteristics.

    PubMed

    LeMoyne, Robert; Mastroianni, Timothy; Grundfest, Warren

    2011-01-01

    The capability to quantify gait characteristics through a wireless accelerometer iPod application in an effectively autonomous environment may alleviate the progressive strain on highly specific medical resources. The iPod consists of the inherent attributes imperative for robust gait quantification, such as a three dimensional accelerometer, data storage, flexible software, and the capacity for wireless transmission of the gait data through email. Based on the synthesis of the integral components of the iPod, a wireless accelerometer iPod application for quantifying gait characteristics has been tested and evaluated in an essentially autonomous environment. The quantified gait acceleration waveforms were wirelessly transmitted using email for postprocessing. The site for the gait experiment occurred in a remote location relative to the location where the postprocessing was conducted. The wireless accelerometer iPod application for quantifying gait characteristics demonstrated sufficient accuracy and consistency.

  1. Accelerometer measurements of acoustic-to-seismic coupling above buried objects.

    PubMed

    Attenborough, Keith; Qin, Qin; Jefferis, Jonathan; Heald, Gary

    2007-12-01

    The surface velocity of sand inside a large PVC container, induced by the sound pressure from either a large loudspeaker radiating into an inverted cone and pipe or a Bruel and Kjaer point source loudspeaker mounted with its axis vertical, has been measured using accelerometers. Results of white noise and stepped frequency excitation are presented. Without any buried object the mass loading of an accelerometer creates resonances in the spectral ratio of sand surface velocity to incident acoustic pressure, i.e., the acoustic-to-seismic (A/S) admittance spectra. The A/S responses above a buried compliant object are larger and distinctive. The linear A/S admittance spectra in the presence of a buried electronic components box have been studied as a function of burial depth and sand state. The nonlinear responses above the buried box have been studied as a function of depth, sand state, and amplitude. Predictions of a modified one-dimensional lumped parameter model have been found to be consistent with the observed nonlinear responses. Also the modified model has been used to explain features of the A/S responses observed when using an accelerometer without any buried object.

  2. Cutting the Cord

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This animation shows the view from the front hazard avoidance cameras on the Mars Exploration Rover Spirit as the rover turns 45 degrees clockwise. This maneuver is the first step in a 3-point turn that will rotate the rover 115 degrees to face west. The rover must make this turn before rolling off the lander because airbags are blocking it from exiting off the front lander petal. Before this crucial turn could take place, engineers instructed the rover to cut the final cord linking it to the lander. The turn took around 30 minutes to complete.

  3. Cutting the Cord-2

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This animation shows the view from the rear hazard avoidance cameras on the Mars Exploration Rover Spirit as the rover turns 45 degrees clockwise. This maneuver is the first step in a 3-point turn that will rotate the rover 115 degrees to face west. The rover must make this turn before rolling off the lander because airbags are blocking it from exiting from the front lander petal. Before this crucial turn took place, engineers instructed the rover to cut the final cord linking it to the lander. The turn took around 30 minutes to complete.

  4. LANCE Q-flex accelerometer qualification test program

    NASA Astrophysics Data System (ADS)

    Hunter, J. S.; Mitchell, J. N.; Hester, T.; Searcy, D.

    1982-03-01

    This report covers the performance obtained on six Sundstrand Q-Flex accelerometers during the qualification test program for the LANCE missile. The Qualification Test Program was divided into three parts: (1) Flight Assurance Tests (FAT), (2) Storage and Transportation Tests (SATT), and (3) Reliability Overstress Tests (ROT). All testing was performed in accordance with Vought accelerometer procurement specification 704-166C dated 8 June 1978.

  5. Optical fiber accelerometer based on a silicon micromachined cantilever

    NASA Astrophysics Data System (ADS)

    Malki, Abdelrafik; Lecoy, Pierre; Marty, Jeanine; Renouf, Christine; Ferdinand, Pierre

    1995-12-01

    An intensity-modulated fiber-optic accelerometer based on backreflection effects has been manufactured and tested. It uses a multimode fiber placed at a spherical mirror center, and the beam intensity is modulated by a micromachined silicon cantilever. This device has applications as an accelerometer and vibrometer for rotating machines. It exhibits an amplitude linearity of +/-1.2% in the range of 0.1-22 m s-2, a frequency linearity of +/-1% in the

  6. A PFV2 accelerometer for high shock applications

    NASA Astrophysics Data System (ADS)

    Tise, Bert; Smith, Talbot

    1989-08-01

    The development, fabrication, and testing of a high-g piezoelectric accelerometer that uses polyvinlylidene fluoride as the piezoelectric transducer is described. The accelerometer is designed to continuously measure accelerations up to 1000,000 g. The device is packages in a 3/8 inch hex head bolt and can include a built-in hybrid buffer to provide a low output impedance analog signal. Included are fabrication procedures, mechanical drawings, and software listings for test data analysis programs.

  7. Quality of GOCE accelerometer data and analysis with ionospheric dynamics during geomagnetically active days

    NASA Astrophysics Data System (ADS)

    Sinem Ince, Elmas; Fomichev, Victor; Floberghagen, Rune; Schlicht, Anja; Martynenko, Oleg; Pagiatakis, Spiros

    2016-07-01

    The Gravity field and steady-state Ocean Circulation Explorer (GOCE) was launched in March, 2009 and completed its mission with great success in November, 2011. GOCE data processing is challenging and not all the disturbances are removed from the gravitational field observations. The disturbances observed in GOCE Vyy gradients around magnetic poles are investigated by using external datasets. It is found that the amplitude of these disturbances increase during geomagnetically active days and can reach up to 5 times the expected noise level of the gradiometer. ACE (Advanced Composition Explorer) and Wind satellites measured electric field and interplanetary magnetic field components have shown that the disturbances observed in the polar regions agree with the increased solar activity. Moreover, equivalent ionospheric currents computed along ascending satellite tracks over North America and Greenland have shown a noticeable correlation with the cross-track and vertical currents and the pointing flux (ExB) components in the satellite cross track direction. Lastly, Canadian Ionosphere and Atmosphere Model (C-IAM) electric field and neutral wind simulations have shown a strong correlation of the enhancement in the ionospheric dynamics during geomagnetically active days and disturbances measured by the GOCE accelerometers over high latitudes. This may be a result of imperfect instrumentation and in-flight calibration of the GOCE accelerometers for an increased geomagnetic activity or a real disturbance on the accelerometers. We use above listed external datasets to understand the causes of the disturbances observed in gravity gradients and reduce/ eliminate them by using response analyses in frequency domain. Based on our test transfer functions, improvement is possible in the quality of the gradients. Moreover, this research also confirms that the accelerometer measurements can be useful to understand the ionospheric dynamics and space weather forecasting.

  8. Performance of several low-cost accelerometers

    USGS Publications Warehouse

    Evans, J.R.; Allen, R.M.; Chung, A. I.; Cochran, E.S.; Guy, R.; Hellweg, M.; Lawrence, J. F.

    2014-01-01

    Several groups are implementing low‐cost host‐operated systems of strong‐motion accelerographs to support the somewhat divergent needs of seismologists and earthquake engineers. The Advanced National Seismic System Technical Implementation Committee (ANSS TIC, 2002), managed by the U.S. Geological Survey (USGS) in cooperation with other network operators, is exploring the efficacy of such systems if used in ANSS networks. To this end, ANSS convened a working group to explore available Class C strong‐motion accelerometers (defined later), and to consider operational and quality control issues, and the means of annotating, storing, and using such data in ANSS networks. The working group members are largely coincident with our author list, and this report informs instrument‐performance matters in the working group’s report to ANSS. Present examples of operational networks of such devices are the Community Seismic Network (CSN; csn.caltech.edu), operated by the California Institute of Technology, and Quake‐Catcher Network (QCN; Cochran et al., 2009; qcn.stanford.edu; November 2013), jointly operated by Stanford University and the USGS. Several similar efforts are in development at other institutions. The overarching goals of such efforts are to add spatial density to existing Class‐A and Class‐B (see next paragraph) networks at low cost, and to include many additional people so they become invested in the issues of earthquakes, their measurement, and the damage they cause.

  9. Factors associated with participant compliance in studies using accelerometers.

    PubMed

    Lee, Paul H; Macfarlane, Duncan J; Lam, T H

    2013-09-01

    Participant compliance is an important issue in studies using accelerometers. Some participants wear the accelerometer for the duration specified by the researchers but many do not. We investigated a range of demographic factors associated with participant compliance in obtaining analyzable accelerometer data. A total of 3601 participants (aged 47.6±13.1 years, 44.6% male) were included. They were asked to wear an accelerometer (ActiGraph) for four consecutive days after completing a household survey during March 2009-January 2011 in Hong Kong. Participants wore the accelerometer on average for 13.9h in a 24-h day. No significant difference was found between males and females (p=0.38). Using log-linear regression, it was found that older participants (0.5% more wearing hours for each year of age, p<0.001), those with full-time job (p<0.01), with tertiary education (p<0.01), non-smokers (p<0.01) and with high self-reported health (p<0.05) wore the accelerometer for more hours. These results provide details for estimating compliance rates for samples with different characteristics and thus sample size calculation to account for participant compliance.

  10. Isolation of a piezoresistive accelerometer used in high acceleration tests

    NASA Astrophysics Data System (ADS)

    Bateman, V. I.; Brown, F. A.; Davie, N. T.

    Both uniaxial and triaxial shock isolation techniques for a piezoresistive accelerometer have been developed for pyroshock and impact tests. The uniaxial shock isolation technique has demonstrated acceptable characteristics for a temperature range of -50 to +186 F and a frequency bandwidth of DC to 10 kHz. The triaxial shock isolation technique has demonstrated acceptable results for a temperature range of -50 to 70 F and a frequency bandwidth of DC to 10 kHz. These temperature ranges, that are beyond the accelerometer manufacturer's operational limits of -30 and +150 F, required the calibration of accelerometers at high shock levels and at the temperature extremes of -50 and +160 F. The purposes of these calibrations were to insure that the accelerometers operated at the field test temperatures and to provide an accelerometer sensitivity at each test temperature. Since there is no NIST-traceable (National Institute of Standards and Technology traceable) calibration capability at shock levels of 5,000 - 15,000 g for the temperature extremes of -50 and +160 F, a method for calibrating and certifying the Hopkinson bar with a transfer standard was developed. Time domain and frequency domain results are given that characterize the Hopkinson bar. The NIST-traceable accuracy for the standard accelerometer in shock is +\\-5%. The Hopkinson bar has been certified by the Sandia Secondary Standards Division with an uncertainty of 6%.

  11. Processing of multi-satellite accelerometer data for thermospheric modelling

    NASA Astrophysics Data System (ADS)

    Doornbos, Eelco; Visser, Pieter N. A. M.; van Helleputte, Tom; van den Ijssel, Jose; Foerster, Matthias; Luehr, Hermann; Rees, David; Koppenwallner, Georg; Fritsche, Bent; Kern, Michael; Haagmans, Roger

    Satellite accelerometers, such as those carried on the CHAMP and GRACE satellites, provide valuable data for improving our knowledge of thermosphere density and winds. These data are now available over a full range of solar activity conditions and over a wide range of heights and local times. The fact that the CHAMP and GRACE accelerometer data sets are largely overlapping in time offers the opportunity to study their synergy. Continuity of this multisatellite accelerometer data set will be provided by ESA's Swarm mission, a constellation of three satellites for studying the Earth's magnetic field. This overview will cover both the processing steps required for converting accelerometer data into density and wind data, and the scientific investigations resulting from this data. Scientific investigations that make use of the accelerometer data sets include comparisons with and adjustment of empirical and physical thermosphere models, studies of the response of the thermosphere on geomagnetic storm conditions and characterization of thermospheric structures by analysis of long-term averages. Accelerometer calibration errors and attitude errors in the satellite aerodynamic model can be largely reduced by making use of data from the satellite's GPS receivers and star cameras. However, considerable uncertainties remain due to insufficient knowledge of the in-track wind speed, the gas-surface interaction and cross-track calibration. These uncertainties can be characterized by using error analysis, by comparing different processing approaches and by comparisons with force models.

  12. Italian spring accelerometer (ISA) a high sensitive accelerometer for ``BepiColombo'' ESA CORNERSTONE

    NASA Astrophysics Data System (ADS)

    Iafolla, V.; Nozzoli, S.

    2001-12-01

    The targets of the ESA CORNERSTONE mission to Mercury "BepiColombo" are concerned with both planetary and magnetospheric physics and to test some aspects of the general relativity. A payload devoted to a set of experiments named radio science is located within one of the three proposed modules, the Mercury Planetary Orbiter (MPO). In particular, a high sensitivity accelerometer ( a min<10 -9√g/ Hz in the range 10 -4- 10 -1 Hz) will measure the inertial acceleration acting on the MPO. Such data, together with tracking data are used to evaluate the purely gravitational trajectory of the MPO, transforming it to a virtual drag-free satellite system. The ISA accelerometer, considered for this mission, is a well-studied instrument developed at the Istituto di Fisica dello Spazio Interplanetario (IFSI), with the financial support of the Agenzia Spaziale Italiana (ASI). A prototype of such an instrument was constructed, matching the requirements of the radio science experiment. Results of the study concerning the use of ISA in the BepiColombo mission are reported here, particular care being devoted to the description of the instrument and to its sensitivity and thermal stabilisation.

  13. Relative performance of several inexpensive accelerometers

    USGS Publications Warehouse

    Evans, John R.; Rogers, John A.

    1995-01-01

    We examined the performance of several low-cost accelerometers for highly cost-driven applications in recording earthquake strong motion. We anticipate applications for such sensors in providing the lifeline and emergency-response communities with an immediate, comprehensive picture of the extent and characteristics of likely damage. We also foresee their use as 'filler' instruments sited between research-grade instruments to provide spatially detailed and near-field records of large earthquakes (on the order of 1000 stations at 600-m intervals in San Fernando Valley, population 1.2 million, for example). The latter applications would provide greatly improved attenuation relationships for building codes and design, the first examples of mainshock information (that is, potentially nonlinear regime) for microzonation, and a suite of records for structural engineers. We also foresee possible applications in monitoring structural inter-story drift during earthquakes, possibly leading to local and remote alarm functions as well as design criteria. This effort appears to be the first of its type at the USGS. It is spurred by rapid advances in sensor technology and the recognition of potential non-classical applications. In this report, we estimate sensor noise spectra, relative transfer functions and cross-axis sensitivity of six inexpensive sensors. We tested three micromachined ('silicon-chip') sensors in addition to classical force-balance and piezoelectric examples. This sample of devices is meant to be representative, not comprehensive. Sensor noise spectra were estimated by recording system output with the sensor mounted on a pneumatically supported 545-kg optical-bench isolation table. This isolation table appears to limit ground motion to below our system noise level. These noise estimates include noise introduced by signal-conditioning circuitry, the analog-to-digital converter (ADC), and noise induced in connecting wiring by ambient electromagnetic fields in

  14. Strong Motion Seismograph Based On MEMS Accelerometer

    NASA Astrophysics Data System (ADS)

    Teng, Y.; Hu, X.

    2013-12-01

    The MEMS strong motion seismograph we developed used the modularization method to design its software and hardware.It can fit various needs in different application situation.The hardware of the instrument is composed of a MEMS accelerometer,a control processor system,a data-storage system,a wired real-time data transmission system by IP network,a wireless data transmission module by 3G broadband,a GPS calibration module and power supply system with a large-volumn lithium battery in it. Among it,the seismograph's sensor adopted a three-axis with 14-bit high resolution and digital output MEMS accelerometer.Its noise level just reach about 99μg/√Hz and ×2g to ×8g dynamically selectable full-scale.Its output data rates from 1.56Hz to 800Hz. Its maximum current consumption is merely 165μA,and the device is so small that it is available in a 3mm×3mm×1mm QFN package. Furthermore,there is access to both low pass filtered data as well as high pass filtered data,which minimizes the data analysis required for earthquake signal detection. So,the data post-processing can be simplified. Controlling process system adopts a 32-bit low power consumption embedded ARM9 processor-S3C2440 and is based on the Linux operation system.The processor's operating clock at 400MHz.The controlling system's main memory is a 64MB SDRAM with a 256MB flash-memory.Besides,an external high-capacity SD card data memory can be easily added.So the system can meet the requirements for data acquisition,data processing,data transmission,data storage,and so on. Both wired and wireless network can satisfy remote real-time monitoring, data transmission,system maintenance,status monitoring or updating software.Linux was embedded and multi-layer designed conception was used.The code, including sensor hardware driver,the data acquisition,earthquake setting out and so on,was written on medium layer.The hardware driver consist of IIC-Bus interface driver, IO driver and asynchronous notification driver. The

  15. Validation of Accelerometer Wear and Nonwear Time Classification Algorithm

    PubMed Central

    Choi, Leena; Liu, Zhouwen; Matthews, Charles E.; Buchowski, Maciej S.

    2011-01-01

    Introduction The use of movement monitors (accelerometers) for measuring physical activity (PA) in intervention and population-based studies is becoming a standard methodology for the objective measurement of sedentary and active behaviors and for validation of subjective PA self-reports. A vital step in PA measurements is classification of daily time into accelerometer wear and nonwear intervals using its recordings (counts) and an accelerometer-specific algorithm. Purpose To validate and improve a commonly used algorithm for classifying accelerometer wear and nonwear time intervals using objective movement data obtained in the whole-room indirect calorimeter. Methods We conducted a validation study of a wear/nonwear automatic algorithm using data obtained from 49 adults and 76 youth wearing accelerometers during a strictly monitored 24-h stay in a room calorimeter. The accelerometer wear and nonwear time classified by the algorithm was compared with actual wearing time. Potential improvements to the algorithm were examined using the minimum classification error as an optimization target. Results The recommended elements in the new algorithm are: 1) zero-count threshold during a nonwear time interval, 2) 90-min time window for consecutive zero/nonzero counts, and 3) allowance of 2-min interval of nonzero counts with the up/downstream 30-min consecutive zero counts window for detection of artifactual movements. Compared to the true wearing status, improvements to the algorithm decreased nonwear time misclassification during the waking and the 24-h periods (all P < 0.001). Conclusions The accelerometer wear/nonwear time algorithm improvements may lead to more accurate estimation of time spent in sedentary and active behaviors. PMID:20581716

  16. Laser cutting with chemical reaction assist

    DOEpatents

    Gettemy, Donald J.

    1992-01-01

    A method for cutting with a laser beam where an oxygen-hydrocarbon reaction is used to provide auxiliary energy to a metal workpiece to supplement the energy supplied by the laser. Oxygen is supplied to the laser focus point on the workpiece by a nozzle through which the laser beam also passes. A liquid hydrocarbon is supplied by coating the workpiece along the cutting path with the hydrocarbon prior to laser irradiation or by spraying a stream of hydrocarbon through a nozzle aimed at a point on the cutting path which is just ahead of the focus point during irradiation.

  17. Laser cutting with chemical reaction assist

    DOEpatents

    Gettemy, D.J.

    1992-11-17

    A method is described for cutting with a laser beam where an oxygen-hydrocarbon reaction is used to provide auxiliary energy to a metal workpiece to supplement the energy supplied by the laser. Oxygen is supplied to the laser focus point on the workpiece by a nozzle through which the laser beam also passes. A liquid hydrocarbon is supplied by coating the workpiece along the cutting path with the hydrocarbon prior to laser irradiation or by spraying a stream of hydrocarbon through a nozzle aimed at a point on the cutting path which is just ahead of the focus point during irradiation. 1 figure.

  18. Characterization of a MEMS Accelerometer for Inertial Navigating Applications

    SciTech Connect

    Kinney, R.D.

    1999-02-12

    Inertial MEMS sensors such as accelerometers and angular rotation sensing devices continue to improve in performance as advances in design and processing are made. Present state-of-the-art accelerometers have achieved performance levels in the laboratory that are consistent with requirements for successful application in tactical weapon navigation systems. However, sensor performance parameters that are of interest to the designer of inertial navigation systems are frequently not adequately addressed by the MEMS manufacturer. This paper addresses the testing and characterization of a MEMS accelerometer from an inertial navigation perspective. The paper discusses test objectives, data reduction techniques and presents results from the test of a three-axis MEMS accelerometer conducted at Sandia National Laboratories during 1997. The test was structured to achieve visibility and characterization of the accelerometer bias and scale factor stability overtime and temperature. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US Department of Energy under contract DE-AC04-94AL85000.

  19. Optimal Placement of Accelerometers for the Detection of Everyday Activities

    PubMed Central

    Cleland, Ian; Kikhia, Basel; Nugent, Chris; Boytsov, Andrey; Hallberg, Josef; Synnes, Kåre; McClean, Sally; Finlay, Dewar

    2013-01-01

    This article describes an investigation to determine the optimal placement of accelerometers for the purpose of detecting a range of everyday activities. The paper investigates the effect of combining data from accelerometers placed at various bodily locations on the accuracy of activity detection. Eight healthy males participated within the study. Data were collected from six wireless tri-axial accelerometers placed at the chest, wrist, lower back, hip, thigh and foot. Activities included walking, running on a motorized treadmill, sitting, lying, standing and walking up and down stairs. The Support Vector Machine provided the most accurate detection of activities of all the machine learning algorithms investigated. Although data from all locations provided similar levels of accuracy, the hip was the best single location to record data for activity detection using a Support Vector Machine, providing small but significantly better accuracy than the other investigated locations. Increasing the number of sensing locations from one to two or more statistically increased the accuracy of classification. There was no significant difference in accuracy when using two or more sensors. It was noted, however, that the difference in activity detection using single or multiple accelerometers may be more pronounced when trying to detect finer grain activities. Future work shall therefore investigate the effects of accelerometer placement on a larger range of these activities. PMID:23867744

  20. Portable cutting apparatus

    DOEpatents

    Gilmore, Richard F.

    1986-01-01

    A remotely operable, portable cutting apparatus detachably secured to the workpiece by laterally spaced clamp assemblies engageable with the workpiece on opposite sides of the intended line of cut. A reciprocal cutter head is mounted between the clamp assemblies and is provided with a traveling abrasive cutting wire adapted to sever the workpiece normal to the longitudinal axis thereof. Dust and debris are withdrawn from the cutting area by a vacuum force through a nozzle mounted on the cutting head.

  1. Portable cutting apparatus

    DOEpatents

    Gilmore, Richard F.

    1986-04-01

    A remotely operable, portable cutting apparatus detachably secured to the workpiece by laterally spaced clamp assemblies engageable with the workpiece on opposite sides of the intended line of cut. A reciprocal cutter head is mounted between the clamp assemblies and is provided with a traveling abrasive cutting wire adapted to sever the workpiece normal to the longitudinal axis thereof. Dust and debris are withdrawn from the cutting area by a vacuum force through a nozzle mounted on the cutting head.

  2. Portable cutting apparatus

    DOEpatents

    Gilmore, R.F.

    1984-07-17

    A remotely operable, portable cutting apparatus detachably secured to the workpiece by laterally spaced clamp assemblies engagable with the workpiece on opposite sides of the intended line of cut. A reciprocal cutter head is mounted between the clamp assemblies and is provided with a traveling abrasive cutting wire adapted to sever the workpiece normal to the longitudinal axis thereof. Dust and debris are withdrawn from the cutting area by a vacuum force through a nozzle mounted on the cutting head.

  3. Real-time estimation of daily physical activity intensity by a triaxial accelerometer and a gravity-removal classification algorithm.

    PubMed

    Ohkawara, Kazunori; Oshima, Yoshitake; Hikihara, Yuki; Ishikawa-Takata, Kazuko; Tabata, Izumi; Tanaka, Shigeho

    2011-06-01

    We have recently developed a simple algorithm for the classification of household and locomotive activities using the ratio of unfiltered to filtered synthetic acceleration (gravity-removal physical activity classification algorithm, GRPACA) measured by a triaxial accelerometer. The purpose of the present study was to develop a new model for the immediate estimation of daily physical activity intensities using a triaxial accelerometer. A total of sixty-six subjects were randomly assigned into validation (n 44) and cross-validation (n 22) groups. All subjects performed fourteen activities while wearing a triaxial accelerometer in a controlled laboratory setting. During each activity, energy expenditure was measured by indirect calorimetry, and physical activity intensities were expressed as metabolic equivalents (MET). The validation group displayed strong relationships between measured MET and filtered synthetic accelerations for household (r 0·907, P < 0·001) and locomotive (r 0·961, P < 0·001) activities. In the cross-validation group, two GRPACA-based linear regression models provided highly accurate MET estimation for household and locomotive activities. Results were similar when equations were developed by non-linear regression or sex-specific linear or non-linear regressions. Sedentary activities were also accurately estimated by the specific linear regression classified from other activity counts. Therefore, the use of a triaxial accelerometer in combination with a GRPACA permits more accurate and immediate estimation of daily physical activity intensities, compared with previously reported cut-off classification models. This method may be useful for field investigations as well as for self-monitoring by general users.

  4. The ISA accelerometer for BepiColombo mission .

    NASA Astrophysics Data System (ADS)

    Iafolla, V.; Fiorenza, E.; Lefevre, C.; Nozzoli, S.; Peron, R.; Reale, A.; Santoli, F.

    The Italian Spring Accelerometer (ISA) will give a fundamental contribution to the Radio Science Experiments of BepiColombo mission, enabling substantial improvement of the knowledge of Mercury's orbit and rotation, and of the relativistic dynamics in the solar system. ISA is a three-axis accelerometer devoted to the measurement of the non-gravitational acceleration of Mercury Planetary Orbiter (MPO), whose knowledge is important in order to fully exploit the quality of the tracking data. ISA shall have an intrinsic noise level of (10^{-9} m/s^2/&sqrt;{Hz}) in the (3 \\cdot 10^{-5}) Hz to (10^{-1}) Hz frequency range, to guarantee the fulfilment of the RSE scientific goals. A comprehensive presentation of ISA accelerometer is given, including details about its scientific and technological features, the updated measurement error budget, the ongoing experimental activities and foreseen calibration and science operations strategies.

  5. Terrestrial Applications of a Nano-g Accelerometer

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    1996-01-01

    The ultra-sensitive accelerometer, developed for NASA to monitor the microgravity environments of Space Shuttle, five orbiters and Space Station, needed to measure accelerations up to 10 mg with an absolute accuracy of 10 nano-g (10(exp -8)g) for at least two orbits (10(exp 4) seconds) to resolve accelerations associated with orbital drag. Also, the accelerometers needed to have less than 10(exp -9) F.S. off-axis sensitivity; to be thermally and magnetically inert; to be immune to quiescent shock, and to have an in-situ calibration capability. Multi-axis compact seismometers, designs that have twelve decades of dynamic range will be described. Density profilometers, precision gradiometers, gyros and vibration isolation designs and applications will be discussed. Finally, examples of transformations of the accelerometer into sensitive anemometers and imaging spectrometers will be presented.

  6. Thermospheric density and winds from GRACE accelerometer data

    NASA Astrophysics Data System (ADS)

    Cheng, Minkang; Tapley, Byron D.; Bettadpur, Srinivas; Ries, John C.

    The high-accuracy accelerometer data carried by the GRACE satellites represents the best measurements of the total surface forces acting on the spacecraft, including atmospheric drag, solar and earth radiation pressure. The GRACE accelerometer data are particularly well suited for exploring the variation in the thermospheric density and winds in response to changes in the solar and magnetic activity. In this study, the total atmospheric neutral density and winds are derived from analysis of the accelerometer data over a six-year period starting August 2002, which spans the complete range of solar activity. This paper will present the comparison of the six-year GRACE density with several density models, including DTM-78, NRLMSIS-00, JB2006 and HASDM. The GRACE-derived thermospheric winds will be compared with the HWM-93 model.

  7. Micromachined force-balance feedback accelerometer with optical displacement detection

    DOEpatents

    Nielson, Gregory N.; Langlois, Eric; Baker, Michael; Okandan, Murat; Anderson, Robert

    2014-07-22

    An accelerometer includes a proof mass and a frame that are formed in a handle layer of a silicon-on-an-insulator (SOI). The proof mass is separated from the frame by a back-side trench that defines a boundary of the proof mass. The accelerometer also includes a reflector coupled to a top surface of the proof mass. An optical detector is located above the reflector at the device side. The accelerometer further includes at least one suspension spring. The suspension spring has a handle anchor that extends downwards from the device side to the handle layer to mechanically support upward and downward movement of the proof mass relative to a top surface of the proof mass.

  8. ISA - An Accelerometer to Detect the Disturbing Accelerations Acting on the Mercury Planetary Orbiter of the BepiColombo ESA Cornerstone Mission to Mercury: on Ground Calibration

    NASA Astrophysics Data System (ADS)

    Iafolla, V.; Lucchesi, D. M.; Nozzoli, S.; Santoli, F.; Fois, M.; Persichini, M.

    2006-06-01

    To reach the ambitious goals of the Radio Science Experiment of the BepiColombo space mission to Mercury, among which the planet structure and rotation and test Einstein's theory of General Relativity (GR) to an unprecedented accuracy, an accelerometer has been selected to fly on-board the MPO (Mercury Planetary Orbiter), the main spacecraft of the two to be placed around the innermost planet of our solar system around 2017. The key role of the on-board accelerometer is to remove from the list of unknowns the non-gravitational accelerations that disturbs the pure gravitational orbit of the MPO spacecraft in the strong radiation environment of Mercury. In this way the ``corrected'' orbit of the MPO may be regarded as a geodesic in the field of Mercury. Then, thanks to the very precise tracking from Earth, the possibility to study Mercury's center-of-mass around the Sun and estimate several parameters related to the planet structure and verify the theory of GR. The selected accelerometer named ISA (Italian Spring Accelerometer) is an high sensitive instrument with an intrinsic noise of 10-10 g⊕ / Hz (with g⊕ ≅ 9.8 m / s2) in the frequency band 3 . 10-5 -10-1 Hz. ISA is a three axis accelerometer with a characteristic configuration, in order to minimize the disturbing accelerations due to the gravity-gradients and the apparent forces on the Nadir pointing MPO spacecraft. Because of the complex and strong radiation environment of Mercury, the modelling of the non-gravitational acceleration is quite difficult, while, with the use of ISA accelerometer we are able to gain a factor 100 in accuracy. In this brief paper we will focus on the characteristics of the ISA accelerometer, on its positioning on-board the MPO and in particularly to the techniques for on ground calibration, avoiding the effects of the Earth gravity.

  9. Cutting state identification

    SciTech Connect

    Berger, B.S.; Minis, I.; Rokni, M.

    1997-12-31

    Cutting states associated with the orthogonal cutting of stiff cylinders are identified through an analysis of the singular values of a Toeplitz matrix of third order cumulants of acceleration measurements. The ratio of the two pairs of largest singular values is shown to differentiate between light cutting, medium cutting, pre-chatter and chatter states. Sequences of cutting experiments were performed in which either depth of cut or turning frequency was varied. Two sequences of experiments with variable turning frequency and five with variable depth of cut, 42 cutting experiments in all, provided a database for the calculation of third order cumulants. Ratios of singular values of cumulant matrices find application in the analysis of control of orthogonal cutting.

  10. Isolation of a piezoresistive accelerometer used in high acceleration tests

    SciTech Connect

    Bateman, V.I.; Brown, F.A.; Davie, N.T.

    1992-12-31

    Both uniaxial and triaxial shock isolation techniques for a piezoresistive accelerometer have been developed for pyroshock and impact tests. The uniaxial shock isolation technique has demonstrated acceptable characteristics for a temperature range of {minus}50{degree}F to +186{degree}F and a frequency bandwidth of DC to 10 kHz. The triaxial shock isolation technique has demonstrated acceptable results for a temperature range of {minus}50{degree}F to 70{degree}F and a frequency bandwidth of DC to 10 kHz. These temperature ranges, that are beyond the accelerometer manufacturer`s operational limits of {minus}30{degree}F and +150{degree}F, required the calibration of accelerometers at high shock levels and at the temperature extremes of {minus}50{degree}F and +160{degree}F. The purposes of these calibrations were to insure that the accelerometers operated at the field test temperatures and to provide an accelerometer sensitivity at each test temperature. Since there is no NIST-traceable (National Institute of Standards and Technology traceable) calibration capability at shock levels of 5,000 g - 15,000 g for the temperature extremes of {minus}50{degree}F and +160{degree}F, a method for calibrating and certifying the Hopkinson bar with a transfer standard was developed. Time domain and frequency domain results are given that characterize the Hopkinson bar. The NIST-traceable accuracy for the standard accelerometer in shock is {plus_minus}5%. The Hopkinson bar has been certified by the Sandia Secondary Standards Division with an uncertainty of 6%.

  11. Extracting Time-Accurate Acceleration Vectors From Nontrivial Accelerometer Arrangements.

    PubMed

    Franck, Jennifer A; Blume, Janet; Crisco, Joseph J; Franck, Christian

    2015-09-01

    Sports-related concussions are of significant concern in many impact sports, and their detection relies on accurate measurements of the head kinematics during impact. Among the most prevalent recording technologies are videography, and more recently, the use of single-axis accelerometers mounted in a helmet, such as the HIT system. Successful extraction of the linear and angular impact accelerations depends on an accurate analysis methodology governed by the equations of motion. Current algorithms are able to estimate the magnitude of acceleration and hit location, but make assumptions about the hit orientation and are often limited in the position and/or orientation of the accelerometers. The newly formulated algorithm presented in this manuscript accurately extracts the full linear and rotational acceleration vectors from a broad arrangement of six single-axis accelerometers directly from the governing set of kinematic equations. The new formulation linearizes the nonlinear centripetal acceleration term with a finite-difference approximation and provides a fast and accurate solution for all six components of acceleration over long time periods (>250 ms). The approximation of the nonlinear centripetal acceleration term provides an accurate computation of the rotational velocity as a function of time and allows for reconstruction of a multiple-impact signal. Furthermore, the algorithm determines the impact location and orientation and can distinguish between glancing, high rotational velocity impacts, or direct impacts through the center of mass. Results are shown for ten simulated impact locations on a headform geometry computed with three different accelerometer configurations in varying degrees of signal noise. Since the algorithm does not require simplifications of the actual impacted geometry, the impact vector, or a specific arrangement of accelerometer orientations, it can be easily applied to many impact investigations in which accurate kinematics need to

  12. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Stefan Miska; Nicholas Takach; Kaveh Ashenayi

    2004-07-31

    We have tested the loop elevation system. We raised the mast to approximately 25 to 30 degrees from horizontal. All went well. However, while lowering the mast, it moved laterally a couple of degrees. Upon visual inspection, severe spalling of the concrete on the face of the support pillar, and deformation of the steel support structure was observed. At this time, the facility is ready for testing in the horizontal position. A new air compressor has been received and set in place for the ACTS test loop. A new laboratory has been built near the ACTS test loop Roughened cups and rotors for the viscometer (RS300) were obtained. Rheologies of aqueous foams were measured using three different cup-rotor assemblies that have different surface roughness. The relationship between surface roughness and foam rheology was investigated. Re-calibration of nuclear densitometers has been finished. The re-calibration was also performed with 1% surfactant foam. A new cuttings injection system was installed at the bottom of the injection tower. It replaced the previous injection auger. A mechanistic model for cuttings transport with aerated mud has been developed. Cuttings transport mechanisms with aerated water at various conditions were experimentally investigated. A total of 39 tests were performed. Comparisons between the model predictions and experimental measurements show a satisfactory agreement. Results from the ultrasonic monitoring system indicated that we could distinguish between different sand levels. We also have devised ways to achieve consistency of performance by securing the sensors in the caps in exactly the same manner as long as the sensors are not removed from the caps. A preliminary test was conducted on the main flow loop at 100 gpm flow rate and 20 lb/min cuttings injection rate. The measured bed thickness using the ultrasonic method showed a satisfactory agreement with nuclear densitometer readings. Thirty different data points were collected after the test

  13. Cutting tool form compensation system and method

    DOEpatents

    Barkman, W.E.; Babelay, E.F. Jr.; Klages, E.J.

    1993-10-19

    A compensation system for a computer-controlled machining apparatus having a controller and including a cutting tool and a workpiece holder which are movable relative to one another along a preprogrammed path during a machining operation utilizes a camera and a vision computer for gathering information at a preselected stage of a machining operation relating to the actual shape and size of the cutting edge of the cutting tool and for altering the preprogrammed path in accordance with detected variations between the actual size and shape of the cutting edge and an assumed size and shape of the cutting edge. The camera obtains an image of the cutting tool against a background so that the cutting tool and background possess contrasting light intensities, and the vision computer utilizes the contrasting light intensities of the image to locate points therein which correspond to points along the actual cutting edge. Following a series of computations involving the determining of a tool center from the points identified along the tool edge, the results of the computations are fed to the controller where the preprogrammed path is altered as aforedescribed. 9 figures.

  14. Cutting tool form compensaton system and method

    DOEpatents

    Barkman, William E.; Babelay, Jr., Edwin F.; Klages, Edward J.

    1993-01-01

    A compensation system for a computer-controlled machining apparatus having a controller and including a cutting tool and a workpiece holder which are movable relative to one another along a preprogrammed path during a machining operation utilizes a camera and a vision computer for gathering information at a preselected stage of a machining operation relating to the actual shape and size of the cutting edge of the cutting tool and for altering the preprogrammed path in accordance with detected variations between the actual size and shape of the cutting edge and an assumed size and shape of the cutting edge. The camera obtains an image of the cutting tool against a background so that the cutting tool and background possess contrasting light intensities, and the vision computer utilizes the contrasting light intensities of the image to locate points therein which correspond to points along the actual cutting edge. Following a series of computations involving the determining of a tool center from the points identified along the tool edge, the results of the computations are fed to the controller where the preprogrammed path is altered as aforedescribed.

  15. Fabrication of a Miniaturized ZnO Nanowire Accelerometer and Its Performance Tests

    PubMed Central

    Kim, Hyun Chan; Song, Sangho; Kim, Jaehwan

    2016-01-01

    This paper reports a miniaturized piezoelectric accelerometer suitable for a small haptic actuator array. The accelerometer is made with zinc oxide (ZnO) nanowire (NW) grown on a copper wafer by a hydrothermal process. The size of the accelerometer is 1.5 × 1.5 mm2, thus fitting the 1.8 × 1.8 mm2 haptic actuator array cell. The detailed fabrication process of the miniaturized accelerometer is illustrated. Performance evaluation of the fabricated accelerometer is conducted by comparing it with a commercial piezoelectric accelerometer. The output current of the fabricated accelerometer increases linearly with the acceleration. The miniaturized ZnO NW accelerometer is feasible for acceleration measurement of small and lightweight devices. PMID:27649184

  16. Improved Signal Processing Technique Leads to More Robust Self Diagnostic Accelerometer System

    NASA Technical Reports Server (NTRS)

    Tokars, Roger; Lekki, John; Jaros, Dave; Riggs, Terrence; Evans, Kenneth P.

    2010-01-01

    The self diagnostic accelerometer (SDA) is a sensor system designed to actively monitor the health of an accelerometer. In this case an accelerometer is considered healthy if it can be determined that it is operating correctly and its measurements may be relied upon. The SDA system accomplishes this by actively monitoring the accelerometer for a variety of failure conditions including accelerometer structural damage, an electrical open circuit, and most importantly accelerometer detachment. In recent testing of the SDA system in emulated engine operating conditions it has been found that a more robust signal processing technique was necessary. An improved accelerometer diagnostic technique and test results of the SDA system utilizing this technique are presented here. Furthermore, the real time, autonomous capability of the SDA system to concurrently compensate for effects from real operating conditions such as temperature changes and mechanical noise, while monitoring the condition of the accelerometer health and attachment, will be demonstrated.

  17. Accuracy improvement in a calibration test bench for accelerometers by a vision system

    NASA Astrophysics Data System (ADS)

    D'Emilia, Giulio; Di Gasbarro, David; Gaspari, Antonella; Natale, Emanuela

    2016-06-01

    A procedure is described in this paper for the accuracy improvement of calibration of low-cost accelerometers in a prototype rotary test bench, driven by a brushless servo-motor and operating in a low frequency range of vibrations (0 to 5 Hz). Vibration measurements by a vision system based on a low frequency camera have been carried out, in order to reduce the uncertainty of the real acceleration evaluation at the installation point of the sensor to be calibrated. A preliminary test device has been realized and operated in order to evaluate the metrological performances of the vision system, showing a satisfactory behavior if the uncertainty measurement is taken into account. A combination of suitable settings of the control parameters of the motion control system and of the information gained by the vision system allowed to fit the information about the reference acceleration at the installation point to the needs of the procedure for static and dynamic calibration of three-axis accelerometers.

  18. A Basic Research for the Development and Evaluation of Novel MEMS Digital Accelerometers

    DTIC Science & Technology

    2013-02-01

    A, to the characteristic physical scale of the flow . In the case of accelerometer beam motion, the characteristic scale for the gas damping problem...and dynamic conditions encountered in the MEMS accelerometer. Typical ESBGK simulation results for the gas flow around the moving accelerometer beam... gas damping response have been compared with measurements of MEMS accelerometer beam closing and opening response done at various acceleration pulse

  19. Self-noise models of five commercial strong-motion accelerometers

    USGS Publications Warehouse

    Ringler, Adam; Evans, John R.; Hutt, Charles R.

    2015-01-01

    To better characterize the noise of a number of commonly deployed accelerometers in a standardized way, we conducted noise measurements on five different models of strong‐motion accelerometers. Our study was limited to traditional accelerometers (Fig. 1) and is in no way exhaustive.

  20. The Evaluation of Physical Stillness with Wearable Chest and Arm Accelerometer during Chan Ding Practice

    PubMed Central

    Chang, Kang-Ming; Chun, Yu-Teng; Chen, Sih-Huei; Lu, Luo; Su, Hsiao-Ting Jannis; Liang, Hung-Meng; Santhosh, Jayasree; Ching, Congo Tak-Shing; Liu, Shing-Hong

    2016-01-01

    Chan Ding training is beneficial to health and emotional wellbeing. More and more people have taken up this practice over the past few years. A major training method of Chan Ding is to focus on the ten Mailuns, i.e., energy points, and to maintain physical stillness. In this article, wireless wearable accelerometers were used to detect physical stillness, and the created physical stillness index (PSI) was also shown. Ninety college students participated in this study. Primarily, accelerometers used on the arms and chest were examined. The results showed that the PSI values on the arms were higher than that of the chest, when participants moved their bodies in three different ways, left-right, anterior-posterior, and hand, movements with natural breathing. Then, they were divided into three groups to practice Chan Ding for approximately thirty minutes. Participants without any Chan Ding experience were in Group I. Participants with one year of Chan Ding experience were in Group II, and participants with over three year of experience were in Group III. The Chinese Happiness Inventory (CHI) was also conducted. Results showed that the PSI of the three groups measured during 20–30 min were 0.123 ± 0.155, 0.012 ± 0.013, and 0.001 ± 0.0003, respectively (p < 0.001 ***). The averaged CHI scores of the three groups were 10.13, 17.17, and 25.53, respectively (p < 0.001 ***). Correlation coefficients between PSI and CHI of the three groups were −0.440, −0.369, and −0.537, respectively (p < 0.01 **). PSI value and the wearable accelerometer that are presently available on the market could be used to evaluate the quality of the physical stillness of the participants during Chan Ding practice. PMID:27447641

  1. The impact of accelerometer use in exercise-associated hypoglycemia prevention in type 1 diabetes.

    PubMed

    Stenerson, Matthew; Cameron, Fraser; Payne, Shelby R; Payne, Sydney L; Ly, Trang T; Wilson, Darrell M; Buckingham, Bruce A

    2015-01-01

    Exercise-associated hypoglycemia is a common adverse event in people with type 1 diabetes. Previous in silico testing by our group demonstrated superior exercise-associated hypoglycemia mitigation when a predictive low glucose suspend (PLGS) algorithm was augmented to incorporate activity data. The current study investigates the effectiveness of an accelerometer-augmented PLGS algorithm in an outpatient exercise protocol. Subjects with type 1 diabetes on insulin pump therapy participated in two structured soccer sessions, one utilizing the algorithm and the other using the subject's regular basal insulin rate. Each subject wore their own insulin pump and a Dexcom G4™ Platinum continuous glucose monitor (CGM); subjects on-algorithm also wore a Zephyr BioHarness™ 3 accelerometer. The algorithm utilized a Kalman filter with a 30-minute prediction horizon. Activity and CGM readings were manually entered into a spreadsheet and at five-minute intervals, the algorithm indicated whether the basal insulin infusion should be on or suspended; any changes were then implemented by study staff. The rate of hypoglycemia during and after exercise (until the following morning) was compared between groups. Eighteen subjects (mean age 13.4 ± 3.7 years) participated in two separate sessions 7-22 days apart. The difference in meter blood glucose levels between groups at each rest period did not achieve statistical significance at any time point. Hypoglycemia during the session was recorded in three on-algorithm subjects, compared to six off-algorithm subjects. In the postexercise monitoring period, hypoglycemia occurred in two subjects who were on-algorithm during the session and four subjects who were off-algorithm. The accelerometer-augmented algorithm failed to prevent exercise-associated hypoglycemia compared to subjects on their usual basal rates. A larger sample size may have achieved statistical significance. Further research involving an automated system, a larger sample

  2. An Approach to Identify Site Response Directivity of Accelerometer Sites and Application to the Iranian Area

    NASA Astrophysics Data System (ADS)

    Del Gaudio, Vincenzo; Pierri, Pierpaolo; Rajabi, Ali M.

    2015-06-01

    In recent years, several workers have found numerous cases of sites characterised by significant azimuthal variation of dynamic response to seismic shaking. The causes of this phenomenon are still unclear, but are possibly related to combinations of geological and geomorphological factors determining a polarisation of resonance effects. To improve their comprehension, it would be desirable to extend the database of observations on this phenomenon. Thus, considering that unrevealed cases of site response directivity can be "hidden" among the sites of accelerometer networks, we developed a two-stage approach of data mining from existing strong motion databases to identify sites affected by directional amplification. The proposed procedure first calculates Arias Intensity tensor components from accelerometer recordings of each site to determine mean directional variations of total shaking energy. Then, at the sites where a significant anisotropy appears in ground motion, azimuthal variations of HVSR values (spectral ratios between horizontal and vertical components of recordings) are analysed to confirm the occurrence of site resonance conditions. We applied this technique to a database of recordings acquired by accelerometer stations in the Iranian area. The results of this investigation pointed out some sites affected by directional resonance that appear to be correlated to the orientation of local tectonic lineaments, these being mostly transversal to the direction of maximum shaking. Comparing Arias Intensities observed at these sites with theoretical estimates provided by ground motion prediction equations, the presence of significant site amplifications was confirmed. The magnitude of the amplification factors appear to be correlated to the results of HVSR analysis, even though the pattern of dispersion of HVSR values suggests that while high peak values of spectral ratios are indicative of strong amplifications, lower values do not necessarily imply lower

  3. Vibration transmissibility on rifle shooter: A comparison between accelerometer and laser Doppler vibrometer data

    NASA Astrophysics Data System (ADS)

    Scalise, L.; Casacanditella, L.; Santolini, C.; Martarelli, M.; Tomasini, E. P.

    2014-05-01

    The transmission of mechanical vibrations from tools to human subjects is known to be potentially dangerous for the circulatory and neurological systems. It is also known that such damages are strictly depending on the intensity and the frequency range of the vibrational signals transferred to the different anatomical districts. In this paper, very high impulsive signals, generated during a shooting by a rifle, will be studied, being such signals characterised by a very high acceleration amplitude as well as high frequency range. In this paper, it will be presented an experimental setup aimed to collect experimental data relative to the transmission of the vibration signals from the rifle to the shoulder of subject during the shooting action. In particular the transmissibility of acceleration signals, as well as of the velocity signals, between the rifle stock and the subject's back shoulder will be measured using two piezoelectric accelerometers and a single point laser Doppler vibrometer (LDV). Tests have been carried out in a shooting lab where a professional shooter has conducted the experiments, using different experimental configurations: two different types of stocks and two kinds of bullets with different weights were considered. Two uniaxial accelerometers were fixed on the stock of the weapon and on the back of the shoulder of the shooter respectively. Vibration from the back shoulder was also measured by means of a LDV simultaneously. A comparison of the measured results will be presented and the pros and cons of the use of contact and non-contact transducers will be discussed taking into account the possible sources of the measurement uncertainty as unwanted sensor vibrations for the accelerometer.

  4. The Evaluation of Physical Stillness with Wearable Chest and Arm Accelerometer during Chan Ding Practice.

    PubMed

    Chang, Kang-Ming; Chun, Yu-Teng; Chen, Sih-Huei; Lu, Luo; Su, Hsiao-Ting Jannis; Liang, Hung-Meng; Santhosh, Jayasree; Ching, Congo Tak-Shing; Liu, Shing-Hong

    2016-07-20

    Chan Ding training is beneficial to health and emotional wellbeing. More and more people have taken up this practice over the past few years. A major training method of Chan Ding is to focus on the ten Mailuns, i.e., energy points, and to maintain physical stillness. In this article, wireless wearable accelerometers were used to detect physical stillness, and the created physical stillness index (PSI) was also shown. Ninety college students participated in this study. Primarily, accelerometers used on the arms and chest were examined. The results showed that the PSI values on the arms were higher than that of the chest, when participants moved their bodies in three different ways, left-right, anterior-posterior, and hand, movements with natural breathing. Then, they were divided into three groups to practice Chan Ding for approximately thirty minutes. Participants without any Chan Ding experience were in Group I. Participants with one year of Chan Ding experience were in Group II, and participants with over three year of experience were in Group III. The Chinese Happiness Inventory (CHI) was also conducted. Results showed that the PSI of the three groups measured during 20-30 min were 0.123 ± 0.155, 0.012 ± 0.013, and 0.001 ± 0.0003, respectively (p < 0.001 ***). The averaged CHI scores of the three groups were 10.13, 17.17, and 25.53, respectively (p < 0.001 ***). Correlation coefficients between PSI and CHI of the three groups were -0.440, -0.369, and -0.537, respectively (p < 0.01 **). PSI value and the wearable accelerometer that are presently available on the market could be used to evaluate the quality of the physical stillness of the participants during Chan Ding practice.

  5. High Sensitivity Optomechanical Reference Accelerometer over 10 kHz

    DTIC Science & Technology

    2014-06-05

    measurements and observations in seismology and gravimetry. 2 High sensitivity optomechanical reference accele Approved for public release; distribution is...and this category of accelerometers, outlining a path for high sensitivity reference acceleration measurements and observations in seismology and...Traditional applications require either high acceleration resolution, such as in gravimetry or seismology well below 100 Hz, or large bandwidths, as for

  6. Estimating Energy Expenditure with the RT3 Triaxial Accelerometer

    ERIC Educational Resources Information Center

    Maddison, Ralph; Jiang, Yannan; Vander Hoorn, Stephen; Mhurchu, Cliona Ni; Lawes, Carlene M. M.; Rodgers, Anthony; Rush, Elaine

    2009-01-01

    The RT3 is a relatively new triaxial accelerometer that has replaced the TriTrac. The aim of this study was to validate the RT3 against doubly labeled water (DLW) in a free-living, mixed weight sample of adults. Total energy expenditure (TEE) was measured over a 15-day period using DLW. Activity-related energy expenditure (AEE) was estimated by…

  7. An overview of the evolution of vibrating beam accelerometer technology

    NASA Astrophysics Data System (ADS)

    Norling, B. L.

    The history of vibrating beam accelerometers (VBA) is briefly outlined, and the current status of VBA technology is reviewed. In particular, attention is given to the VBA design fundamentals and the performance characteristics of several state-of-the-art VBA models. Finally, prospects for the future development of VBAs and the effect of VBA technology on the inertial navigation industry are discussed.

  8. Micromachined low frequency rocking accelerometer with capacitive pickoff

    DOEpatents

    Lee, Abraham P.; Simon, Jonathon N.; McConaghy, Charles F.

    2001-01-01

    A micro electro mechanical sensor that uses capacitive readout electronics. The sensor involves a micromachined low frequency rocking accelerometer with capacitive pickoff fabricated by deep reactive ion etching. The accelerometer includes a central silicon proof mass, is suspended by a thin polysilicon tether, and has a moving electrode (capacitor plate or interdigitated fingers) located at each end the proof mass. During movement (acceleration), the tethered mass moves relative to the surrounding packaging, for example, and this defection is measured capacitively by a plate capacitor or interdigitated finger capacitor, having the cooperating fixed electrode (capacitor plate or interdigitated fingers) positioned on the packaging, for example. The micromachined rocking accelerometer has a low frequency (<500 Hz), high sensitivity (.mu.G), with minimal power usage. The capacitors are connected to a power supply (battery) and to sensor interface electronics, which may include an analog to digital (A/D) converter, logic, RF communication link, antenna, etc. The sensor (accelerometer) may be, for example, packaged along with the interface electronics and a communication system in a 2".times.2".times.2" cube. The proof mass may be asymmetric or symmetric. Additional actuating capacitive plates may be used for feedback control which gives a greater dynamic range.

  9. GPS-Based Reduced Dynamic Orbit Determination Using Accelerometer Data

    NASA Technical Reports Server (NTRS)

    VanHelleputte, Tom; Visser, Pieter

    2007-01-01

    Currently two gravity field satellite missions, CHAMP and GRACE, are equipped with high sensitivity electrostatic accelerometers, measuring the non-conservative forces acting on the spacecraft in three orthogonal directions. During the gravity field recovery these measurements help to separate gravitational and non-gravitational contributions in the observed orbit perturbations. For precise orbit determination purposes all these missions have a dual-frequency GPS receiver on board. The reduced dynamic technique combines the dense and accurate GPS observations with physical models of the forces acting on the spacecraft, complemented by empirical accelerations, which are stochastic parameters adjusted in the orbit determination process. When the spacecraft carries an accelerometer, these measured accelerations can be used to replace the models of the non-conservative forces, such as air drag and solar radiation pressure. This approach is implemented in a batch least-squares estimator of the GPS High Precision Orbit Determination Software Tools (GHOST), developed at DLR/GSOC and DEOS. It is extensively tested with data of the CHAMP and GRACE satellites. As accelerometer observations typically can be affected by an unknown scale factor and bias in each measurement direction, they require calibration during processing. Therefore the estimated state vector is augmented with six parameters: a scale and bias factor for the three axes. In order to converge efficiently to a good solution, reasonable a priori values for the bias factor are necessary. These are calculated by combining the mean value of the accelerometer observations with the mean value of the non-conservative force models and empirical accelerations, estimated when using these models. When replacing the non-conservative force models with accelerometer observations and still estimating empirical accelerations, a good orbit precision is achieved. 100 days of GRACE B data processing results in a mean orbit fit of

  10. Application of inertial instruments for DSN antenna pointing and tracking

    NASA Technical Reports Server (NTRS)

    Eldred, D. B.; Nerheim, N. M.; Holmes, K. G.

    1990-01-01

    The feasibility of using inertial instruments to determine the pointing attitude of the NASA Deep Space Network antennas is examined. The objective is to obtain 1 mdeg pointing knowledge in both blind pointing and tracking modes to facilitate operation of the Deep Space Network 70 m antennas at 32 GHz. A measurement system employing accelerometers, an inclinometer, and optical gyroscopes is proposed. The initial pointing attitude is established by determining the direction of the local gravity vector using the accelerometers and the inclinometer, and the Earth's spin axis using the gyroscopes. Pointing during long-term tracking is maintained by integrating the gyroscope rates and augmenting these measurements with knowledge of the local gravity vector. A minimum-variance estimator is used to combine measurements to obtain the antenna pointing attitude. A key feature of the algorithm is its ability to recalibrate accelerometer parameters during operation. A survey of available inertial instrument technologies is also given.

  11. Device for cutting protrusions

    DOEpatents

    Bzorgi, Fariborz M.

    2011-07-05

    An apparatus for clipping a protrusion of material is provided. The protrusion may, for example, be a bolt head, a nut, a rivet, a weld bead, or a temporary assembly alignment tab protruding from a substrate surface of assembled components. The apparatus typically includes a cleaver having a cleaving edge and a cutting blade having a cutting edge. Generally, a mounting structure configured to confine the cleaver and the cutting blade and permit a range of relative movement between the cleaving edge and the cutting edge is provided. Also typically included is a power device coupled to the cutting blade. The power device is configured to move the cutting edge toward the cleaving edge. In some embodiments the power device is activated by a momentary switch. A retraction device is also generally provided, where the retraction device is configured to move the cutting edge away from the cleaving edge.

  12. New modes and mechanisms of thermospheric mass density variations from GRACE accelerometers

    NASA Astrophysics Data System (ADS)

    Calabia, Andres; Jin, Shuanggen

    2016-11-01

    Monitoring and understanding the upper atmosphere processes is important for orbital decay and space physics. Nowadays, Low Earth Orbit (LEO) accelerometers provide a unique opportunity to study thermospheric density variations with unprecedented details. In this paper, thermospheric mass densities variations from Gravity Recovery and Climate Experiment (GRACE) accelerometers are investigated for the period 2003-2016 using the principal component analysis (PCA). The resulting modes are analyzed and parameterized in terms of solar and magnetospheric forcing, local solar time (LST), and annual variations. A better understanding of global thermospheric air density variations is presented, which validates the suitability of our technique and model. The parameterization of the subsolar-point annual variation shows two maxima around June and only one in December. The LST parameterization shows a new fluctuation controlling a middle latitude four-wave pattern, with two maxima at 12 h and 21 h LST and two minima at 1 h and 17 h LST. Our parameterizations are suitable to represent small-scale variations including, e.g., the equatorial mass density anomaly (EMA) and the midnight density maximum (MDM). Finally, the residuals are analyzed in the spectral domain, and additional contributions are found at the frequencies of the radiational tides and at the periods of 83, 93, 152, and 431 days.

  13. Bias determination for space accelerometers using the ZARM Catapult system - experimental setup and data analysis

    NASA Astrophysics Data System (ADS)

    Selig, Hanns; Santos Rodrigues, Manuel; Touboul, Pierre; Liorzou, Françoise

    2012-07-01

    Accelerometers for space applications - like the electrostatic differential accelrometer for the MICROSCOPE mission for testing the equivalence principle in space - have to be tested and qualified in μg-conditions in order to demonstrate the system operation and to determine the characteristic sensor parameters. One important characteristic property is the sensor bias. In principle one can determine the sensor bias directly by using the ZARM catapult system as test platform. Even in the evacuated drop tube the residual air pressure results in an air friction that depends on the capsule velocity. At the apex (highest point of the capsule trajectory) the acceleration (relative to the gravitational acceleration g) becomes zero due to the zero velocity at the apex. The direct measurement of the vertical linear acceleration sensor bias is affected by some additional effects that have to be understood in order to be able to determine the sensor bias. Two catapult campaigns have been carried out to demonstrate the principles of the bias determination using a SuperStar accelerometer (Onera). The presentation gives an overview on the experimental setup and on the corresponding data analysis.

  14. Design and implementation of a novel sliding mode sensing architecture for capacitive MEMS accelerometers

    NASA Astrophysics Data System (ADS)

    Sarraf, E. H.; Cousins, B.; Cretu, E.; Mirabbasi, S.

    2011-11-01

    We propose novel feedback control and sensing schemes based on sliding mode control (SMC) for closed-loop micro-accelerometers as alternative digital control architectures to sigma-delta (ΣΔ) approaches. The under-damped micro-device has been designed in Coventorware, fabricated in SOIMUMPs (25 µm thick structural layer) technology and experimentally characterized using a Polytec MSA-500 (micro-system analyzer) equipment. To verify the system architecture robustness, the application of SMC is extended to an over-damped accelerometer model. In either case, the SMC demonstrates the repositioning of the proof mass to null position; however, the over-damped model exhibits shorter transition time (15 ms for 1g acceleration) due to the increased damping. In addition to that, we extend the usage of SMC beyond the classical actuation problem to a novel sensing problem where we demonstrate the extraction of the external acceleration measurement from the switching behavior along the sliding surface. An optimized fixed-point implementation is targeted on a field-programmable gate array (FPGA) using rapid prototyping methodology, where the new proposed method has been compared for reference with a control scheme that employs a ΣΔ modulator. The SMC-based architecture is advantageous in terms of hardware complexity, and the control of the number of degrees of freedom required by an inertial measurement unit can be accommodated on a low-cost FPGA device. SMC offers a sound theoretical framework for the nonlinear control of inertial sensors.

  15. Mechanical fault detection of electric motors by laser vibrometer and accelerometer measurements

    NASA Astrophysics Data System (ADS)

    Cristalli, C.; Paone, N.; Rodríguez, R. M.

    2006-08-01

    This paper presents a comparative study between accelerometer and laser vibrometer measurements aimed at on-line quality control carried out on the universal motors used in washing machines, which exhibit defects localised mainly in the bearings, including faults in the cage, in the rolling element and in the outer and inner ring. A set of no defective and defective motors were analysed by means of the acceleration signal provided by the accelerometer, and the displacement and velocity signals given by a single-point laser vibrometer. Advantages and disadvantages of both absolute and relative sensors and of contact and non-contact instrumentation are discussed taking into account the applicability to real on-line quality control measurements and bringing to light the related measurement problems due to the specific environmental conditions of assembly lines and sensor installation constraints. The performance of different signal-processing algorithms is discussed: RMS computation at steady-state proves effective for pass or fail diagnosis, while the amplitude of selected frequencies in the averaged spectra allows also for classification of a variety of special faults in bearings. Joint time-frequency analysis output data can be successfully used for pass or fail diagnosis during transients, thus achieving a remarkable reduction in testing time, which is important for on-line diagnostics.

  16. High performance, accelerometer-based control of the Mini-MAST structure

    NASA Astrophysics Data System (ADS)

    Collins, Emmanuel G., Jr.; King, James A.; Phillips, Douglas J.; Hyland, David C.

    1992-08-01

    Many large space system concepts will require active vibration control to satisfy critical performance requirements such as line of sight pointing accuracy and constraints on rms surface roughness. In order for these concepts to become operational, it is imperative that the benefits of active vibration control be shown to be practical in ground based experiments. The results of an experiment shows the successful application of the Maximum Entropy/Optical Projection control design methodology to active vibration control for a flexible structure. The testbed is the Mini-Mast structure at NASA-Langley and has features dynamically traceable to future space systems. To maximize traceability to real flight systems, the controllers were designed and implemented using sensors (four accelerometers and one rate gyro) that are actually mounted to the structure. Ground mounted displacement sensors that could greatly ease the control design task were available but were used only for performance evaluation. The use of the accelerometers increased the potential of destabilizing the system due to spillover effects and motivated the use of precompensation strategy to achieve sufficient compensator roll-off.

  17. Towards uniform accelerometry analysis: a standardization methodology to minimize measurement bias due to systematic accelerometer wear-time variation.

    PubMed

    Katapally, Tarun R; Muhajarine, Nazeem

    2014-05-01

    variables yielded more stable results with narrower confidence intervals and smaller standard errors. Standardization of accelerometer data is effective in not only minimizing measurement bias due to systematic wear-time variation, but also to provide a uniform platform to compare results within and between populations and studies. Key pointsSystematic variation in accelerometer wear-time both, within and between participants results in measurement bias.Standardization of data after controlling for wear-time produces stable outcome variables.Descriptive and multivariate analyses conducted with standardized outcome variables minimize measurement bias.

  18. Characteristics associated with requested and required accelerometer wear in children

    PubMed Central

    Wells, Sian L; Kipping, Ruth R; Jago, Russell; Brown, Judith; Hucker, Daniel; Blackett, Ali; Lawlor, Debbie A

    2013-01-01

    Objective To investigate characteristics associated with wearing an accelerometer for the required and requested time among 8-year-old to 10-year-old children. Design Cross-sectional. Setting 60 Bristol and North Somerset primary schools taking part in the ‘Active for Life Year 5’ randomised controlled trial (RCT) in 2011. Participants 2048 children, aged 8–10 years, invited to wear an accelerometer for 5 days of recording. Primary outcome measure Numbers meeting required wear-time for inclusion in main RCT analysis (≥8 h/day ≥3 days) and numbers meeting requested wear-time (≥8 h/day for all 5 days). Results 817 (40%) of the children wore the accelerometer for the requested time and 1629 (80%) for the required time. In adjusted multivariable analyses the odds of wearing the accelerometer for the required time were greater in females as compared with males (OR 1.76 (1.42–2.18)), those with higher scores for reporting their mother restricted time on sedentary behaviours (1.26 (1.04–1.52) per increase of 1 on a 1–4 scale) and in children from schools with larger year group sizes (1.01 (1.00–1.02) per additional child). Living in a neighbourhood with higher levels of deprivation (0.49 (0.33–0.72) comparing highest to lowest third of the deprivation score) or reporting higher levels of weekday outdoor play (0.97 (0.94, 1.00) per 30 min more) were associated with reduced odds of meeting required time. Results were essentially the same for requested wear-time. Other characteristics, including child body mass index, were not associated with required or requested wear-time. Conclusions Only 40% of children wore the accelerometer for the requested time but 80% fulfilled the required criteria to be included in the main study analyses. Knowing which characteristics are associated with accelerometer wear could help target interventions to increase wear-time. PMID:23975106

  19. Application of high-rate cutting tools

    NASA Astrophysics Data System (ADS)

    Moriarty, John L., Jr.

    1989-03-01

    Widespread application of the newest high-rate cutting tools to the most appropriate jobs is slowed by the sheer magnitude of developments in tool types, materials, workpiece applications, and by the rapid pace of change. Therefore, a study of finishing and roughing sizes of coated carbide inserts having a variety of geometries for single point turning was completed. The cutting tools were tested for tool life, chip quality, and workpiece surface finish at various cutting conditions with medium alloy steel. An empirical wear-life data base was established, and a computer program was developed to facilitate technology transfer, assist selection of carbide insert grades, and provide machine operating parameters. A follow-on test program was implemented suitable for next generation coated carbides, rotary cutting tools, cutting fluids, and ceramic tool materials.

  20. Measurement of Cut Front Properties in Laser Cutting

    NASA Astrophysics Data System (ADS)

    Thombansen, Ulrich; Hermanns, Torsten; Molitor, Thomas; Pereira, Milton; Schulz, Wolfgang

    Cut-front properties are a key variable in laser-cutting and thus of major importance for self-optimization. Within the Cluster of Excellence at RWTH Aachen University, several achievements were made in setting up sensor-systems that provide information on the operating-point of this melt-based manufacturing process. These achievements contribute to a gradual increase in system-transparency which is seen as an enabler for self-optimization. Instead of searching for a single measurand to characterize the course of the process, an approach is being presented which establishesa surrogate criterion to allow determination of the current operating-point. In the depicted area, this is done by joining sources of information from process observation, determining boundary-conditions such as actual feed-rate and modeling of process-variables. Although process-variables like properties of the cutting-front are influenced through more than one process parameter, a concept for a sensor-system is reported showing the correlation between properties of the melt-front and the current feed-rate. The results are compared to a solution derived from process-simulation.

  1. Laser cutting plastic materials

    SciTech Connect

    Van Cleave, R.A.

    1980-08-01

    A 1000-watt CO/sub 2/ laser has been demonstrated as a reliable production machine tool for cutting of plastics, high strength reinforced composites, and other nonmetals. More than 40 different plastics have been laser cut, and the results are tabulated. Applications for laser cutting described include fiberglass-reinforced laminates, Kevlar/epoxy composites, fiberglass-reinforced phenolics, nylon/epoxy laminates, ceramics, and disposable tooling made from acrylic.

  2. Pioneer Anomaly and Space Accelerometer for Gravity Test

    NASA Astrophysics Data System (ADS)

    Levy, Agnès; Christophe, Bruno; Reynaud, Serge

    2006-06-01

    The Pioneer 10 and 11 spacecraft are subject to an unexplained acceleration which has a constant value of (8.74 1.33) \\cdot 10-10 m\\cdot s-2 and seems to be directed toward the sun. The hypotheses to explain this anomaly are either technical artifacts or new physics. This presentation deals with the unfolding of two aspects of my thesis: Doppler and telemetry data analysis with the objective to investigate the nature of the anomaly, and adapation of an ONERA accelerometer for a future mission in which the anomaly will be confirmed and more precisely measured. The presence of an accelerometer is mandatory for the identification of the anomaly's origin.

  3. A Low Frequency FBG Accelerometer with Symmetrical Bended Spring Plates.

    PubMed

    Liu, Fufei; Dai, Yutang; Karanja, Joseph Muna; Yang, Minghong

    2017-01-22

    To meet the requirements for low-frequency vibration monitoring, a new type of FBG (fiber Bragg grating) accelerometer with a bended spring plate is proposed. Two symmetrical bended spring plates are used as elastic elements, which drive the FBG to produce axial strains equal in magnitude but opposite in direction when exciting vibrations exist, leading to doubling the wavelength shift of the FBG. The mechanics model and a numerical method are presented in this paper, with which the influence of the structural parameters on the sensitivity and the eigenfrequency are discussed. The test results show that the sensitivity of the accelerometer is more than 1000 pm/g when the frequency is within the 0.7-20 Hz range.

  4. A Low Frequency FBG Accelerometer with Symmetrical Bended Spring Plates

    PubMed Central

    Liu, Fufei; Dai, Yutang; Karanja, Joseph Muna; Yang, Minghong

    2017-01-01

    To meet the requirements for low-frequency vibration monitoring, a new type of FBG (fiber Bragg grating) accelerometer with a bended spring plate is proposed. Two symmetrical bended spring plates are used as elastic elements, which drive the FBG to produce axial strains equal in magnitude but opposite in direction when exciting vibrations exist, leading to doubling the wavelength shift of the FBG. The mechanics model and a numerical method are presented in this paper, with which the influence of the structural parameters on the sensitivity and the eigenfrequency are discussed. The test results show that the sensitivity of the accelerometer is more than 1000 pm/g when the frequency is within the 0.7–20 Hz range. PMID:28117740

  5. Guidelines for Standardized Testing of Broadband Seismometers and Accelerometers

    USGS Publications Warehouse

    Hutt, Charles R.; Evans, John R.; Followill, Fred; Nigbor, Robert L.; Wielandt, Erhard

    2010-01-01

    Testing and specification of seismic and earthquake-engineering sensors and recorders has been marked by significant variations in procedures and selected parameters. These variations cause difficulty in comparing such specifications and test results. In July 1989, and again in May 2005, the U.S. Geological Survey hosted international pub-lic/private workshops with the goal of defining widely accepted guidelines for the testing of seismological inertial sensors, seismometers, and accelerometers. The Proceedings of the 2005 workshop have been published and include as appendix 6 the report of the 1989 workshop. This document represents a collation and rationalization of a single set of formal guidelines for testing and specifying broadband seismometers and accelerometers.

  6. Influence of cutting parameters on the depth of subsurface deformed layer in nano-cutting process of single crystal copper.

    PubMed

    Wang, Quanlong; Bai, Qingshun; Chen, Jiaxuan; Su, Hao; Wang, Zhiguo; Xie, Wenkun

    2015-12-01

    Large-scale molecular dynamics simulation is performed to study the nano-cutting process of single crystal copper realized by single-point diamond cutting tool in this paper. The centro-symmetry parameter is adopted to characterize the subsurface deformed layers and the distribution and evolution of the subsurface defect structures. Three-dimensional visualization and measurement technology are used to measure the depth of the subsurface deformed layers. The influence of cutting speed, cutting depth, cutting direction, and crystallographic orientation on the depth of subsurface deformed layers is systematically investigated. The results show that a lot of defect structures are formed in the subsurface of workpiece during nano-cutting process, for instance, stair-rod dislocations, stacking fault tetrahedron, atomic clusters, vacancy defects, point defects. In the process of nano-cutting, the depth of subsurface deformed layers increases with the cutting distance at the beginning, then decreases at stable cutting process, and basically remains unchanged when the cutting distance reaches up to 24 nm. The depth of subsurface deformed layers decreases with the increase in cutting speed between 50 and 300 m/s. The depth of subsurface deformed layer increases with cutting depth, proportionally, and basically remains unchanged when the cutting depth reaches over 6 nm.

  7. Champ Accelerometer: Evaluation and Contribution To The Gravity Mission

    NASA Astrophysics Data System (ADS)

    Perosanz, F.; Loyer, S.; Bruinsma, S.; Tamagnan, D.; Lemoine, J. M.; Biancale, R.; Fayard, T.; Vales, N.; Touboul, P.

    The STAR accelerometer on-board the German CHAMP satellite delivers non- gravitational accelerations with an unprecedented resolution. This study presents the global evaluation of the instrument in terms of continuous measurement and "House Keeping" parameters surveying, a posteriori calibration strategy and results and mis- function analysis and correction. In addition the contribution of the STAR accelerom- eter to dynamic orbit computation and gravity modelling is evaluated. Different orbit fit solutions and geoid models resulting from gravity field test models are compared.

  8. High resolution interface circuit for closed-loop accelerometer

    NASA Astrophysics Data System (ADS)

    Liang, Yin; Xiaowei, Liu; Weiping, Chen; Zhiping, Zhou

    2011-04-01

    This paper reports a low noise switched-capacitor CMOS interface circuit for the closed-loop operation of a capacitive accelerometer. The time division multiplexing of the same electrode is adopted to avoid the strong feedthrough between capacitance sensing and electrostatic force feedback. A PID controller is designed to ensure the stability and dynamic response of a high Q closed-loop accelerometer with a vacuum package. The architecture only requires single ended operational amplifiers, transmission gates and capacitors. Test results show that a full scale acceleration of ±3 g, non-linearity of 0.05% and signal bandwidth of 1000 Hz are achieved. The complete module operates from a ±5 V supply and has a measured sensitivity of 1.2 V/g with a noise of floor of in closed-loop. The chip is fabricated in the 2 μm two-metal and two-poly n-well CMOS process with an area of 15.2 mm2. These results prove that this circuit is suitable for high performance micro-accelerometer applications like seismic detection and oil exploration.

  9. Measuring gravitation near Mercury: the contribution of ISA accelerometer

    NASA Astrophysics Data System (ADS)

    Iafolla, Valerio; Peron, Roberto; Lucchesi, David; Santoli, Francesco; Lefevre, Carlo; Fiorenza, Emiliano; Nozzoli, Sergio; Lucente, Marco; Magnafico, Carmelo

    2012-07-01

    The forthcoming BepiColombo mission for the exploration of the planet Mercury will include a comprehensive set of experiments --- the so--called Radio Science Experiments (RSE) --- in order to measure the gravitational field of the planet, its rotation, and to perform precise tests of Einstein's general theory of relativity. Fundamental piece of RSE is the high--sensitivity ISA (Italian Spring Accelerometer) accelerometer. It will directly measure the strong non--gravitational perturbations acting on Mercury Planetary Orbiter spacecraft, which are an important source of error in the RSE meaurements. Being the first time for an high--sensitivity accelerometer onboard an interplanetary mission, a number of choices had to be made and several issues had to be faced in the design phases. Following a general description of the instrument scientific objectives, its working and operations will be described. Emphasis will be given on the complex calibration procedures required in the various mission phases and on the integration of the measurements with the overall RSE operations and data analysis.

  10. Citizen Sensors for SHM: Use of Accelerometer Data from Smartphones

    PubMed Central

    Feng, Maria; Fukuda, Yoshio; Mizuta, Masato; Ozer, Ekin

    2015-01-01

    Ubiquitous smartphones have created a significant opportunity to form a low-cost wireless Citizen Sensor network and produce big data for monitoring structural integrity and safety under operational and extreme loads. Such data are particularly useful for rapid assessment of structural damage in a large urban setting after a major event such as an earthquake. This study explores the utilization of smartphone accelerometers for measuring structural vibration, from which structural health and post-event damage can be diagnosed. Widely available smartphones are tested under sinusoidal wave excitations with frequencies in the range relevant to civil engineering structures. Large-scale seismic shaking table tests, observing input ground motion and response of a structural model, are carried out to evaluate the accuracy of smartphone accelerometers under operational, white-noise and earthquake excitations of different intensity. Finally, the smartphone accelerometers are tested on a dynamically loaded bridge. The extensive experiments show satisfactory agreements between the reference and smartphone sensor measurements in both time and frequency domains, demonstrating the capability of the smartphone sensors to measure structural responses ranging from low-amplitude ambient vibration to high-amplitude seismic response. Encouraged by the results of this study, the authors are developing a citizen-engaging and data-analytics crowdsourcing platform towards a smartphone-based Citizen Sensor network for structural health monitoring and post-event damage assessment applications. PMID:25643056

  11. Microseismic Monitoring of the Mounds Drill Cuttings Injection Tests

    SciTech Connect

    Branagan, P.T.; Mahrer, K.D.; Moschovidis, Z.A.; Warpinski, N.R.; Wolhart, S.L.

    1999-01-25

    This paper describes the microseismic mapping of repeated injections of drill cuttings into two separate formations at a test site near Mounds, OK. Injections were performed in sandstone and shale formations at depths of 830 and 595 m, respectively. Typical injection disposal was simulated using multiple small-volume injections over a three-day period, with long shut-in periods interspersed between the injections. Microseismic monitoring was achieved using a 5-level array of wireline-run, triaxial- accelerometer receivers in a monitor well 76 m from the disposed well. Results of the mapped microseismic locations showed that the disposal domti W= generally aligns with the major horizontal stress with some variations in azimuth and that wide variations in height and length growth occurred with continued injections. These experiments show that the cuttings injection process cm be adequately monitored from a downhole, wireline-run receiver array, thus providing process control and environmental assurance.

  12. Cutting Class Harms Grades

    ERIC Educational Resources Information Center

    Taylor, Lewis A., III

    2012-01-01

    An accessible business school population of undergraduate students was investigated in three independent, but related studies to determine effects on grades due to cutting class and failing to take advantage of optional reviews and study quizzes. It was hypothesized that cutting classes harms exam scores, attending preexam reviews helps exam…

  13. When Students Cut Themselves

    ERIC Educational Resources Information Center

    Malikow, Max

    2006-01-01

    Masochism, the irrational self-infliction of pain, is more easily defined than understood. Once, a teacher used the word "cutting" only reference to a student skipping class. But, in recent years, it has taken on additional meaning. Cutting, or self-injury, is a deliberate self-harming behavior but without conscious suicidal ideation. To define…

  14. Fundamentals of cutting.

    PubMed

    Williams, J G; Patel, Y

    2016-06-06

    The process of cutting is analysed in fracture mechanics terms with a view to quantifying the various parameters involved. The model used is that of orthogonal cutting with a wedge removing a layer of material or chip. The behaviour of the chip is governed by its thickness and for large radii of curvature the chip is elastic and smooth cutting occurs. For smaller thicknesses, there is a transition, first to plastic bending and then to plastic shear for small thicknesses and smooth chips are formed. The governing parameters are tool geometry, which is principally the wedge angle, and the material properties of elastic modulus, yield stress and fracture toughness. Friction can also be important. It is demonstrated that the cutting process may be quantified via these parameters, which could be useful in the study of cutting in biology.

  15. Monitoring mobility in older adults using global positioning system (GPS) watches and accelerometers: a feasibility study.

    PubMed

    Webber, Sandra C; Porter, Michelle M

    2009-10-01

    This exploratory study examined the feasibility of using Garmin global positioning system (GPS) watches and ActiGraph accelerometers to monitor walking and other aspects of community mobility in older adults. After accuracy at slow walking speeds was initially determined, 20 older adults (74.4 +/- 4.2 yr) wore the devices for 1 day. Steps, distances, and speeds (on foot and in vehicle) were determined. GPS data acquisition varied from 43 min to over 12 hr, with 55% of participants having more than 8 hr between initial and final data-collection points. When GPS data were acquired without interruptions, detailed mobility information was obtained regarding the timing, distances covered, and speeds reached during trips away from home. Although GPS and accelerometry technology offer promise for monitoring community mobility patterns, new GPS solutions are required that allow for data collection over an extended period of time between indoor and outdoor environments.

  16. The BepiColombo Mission to Mercury: reaction wheels desaturation manoeuvres and the ISA accelerometer Δ →V measurements

    NASA Astrophysics Data System (ADS)

    Iafolla, Valerio; Nozzoli, Sergio; Lucchesi, David; Santoli, Francesco; Peron, Roberto; Fiorenza, Emiliano; Lefevre, Carlo; Reale, Andrea

    2010-05-01

    The MPO will be a three-axis stabilized spacecraft and nadir pointing to Mercury center-of-mass. Such a pointing, needed for the very ambitious goals of the ESA space mission to Mercury denominated BepiColombo, is reached thanks to the onboard reaction wheels, and it is also required during the unobserved (from Earth) arcs. The unavoidable manoeuvres of desaturation of the reaction wheels, which are necessary to remove the accumulated angular momentum, represent a clear reduction of the accuracy of the objectives of the ESA space mission. Indeed, during these manoeuvres the spacecraft thrusters are fired -- to guarantee the planet center-of-mass pointing -- and directly impact the accuracy of the propagated state-vector of the satellite at the beginning of the subsequent observed arc. Their impact is quantified by their number, position along the orbit and, especially, in the uncertainty in the linear momentum transferred to the spacecraft. This presentation is devoted to prove the feasibility of the measurements of the transferred momentum by the thruster thanks to the onboard accelerometer ISA. Therefore, such measurements will be an essential ingredient in order to preserve the accuracy of the BepiColombo Radio Science Experiments and of the pointing accuracy of other onboard instruments, as is the case of BELA. This additional capability of ISA strengthen once more the key rôle of the accelerometer in the BepiColombo mission to Mercury.

  17. Development of a quartz digital accelerometer for environmental sensing and navigation applications

    SciTech Connect

    Kass, W.J.; Vianco, P.T.

    1993-03-01

    A quartz digital accelerometer has been developed which uses double ended tuning forks as the active sensing elements. The authors have demonstrated the ability of this accelerometer to be capable of acceleration measurements between {+-}150G with {+-}0.5G accuracy. They have further refined the original design and assembly processes to produce accelerometers with < 1mG stability in inertial measurement applications. This report covers the development, design, processing, assembly, and testing of these devices.

  18. INTERNAL CUTTING DEVICE

    DOEpatents

    Russell, W.H. Jr.

    1959-06-30

    A device is described for removing material from the interior of a hollow workpiece so as to form a true spherical internal surface in a workpiece, or to cut radial slots of an adjustable constant depth in an already established spherical internal surface. This is accomplished by a spring loaded cutting tool adapted to move axially wherein the entire force urging the tool against the workpiece is derived from the spring. Further features of importance involve the provision of a seal between the workpiece and the cutting device and a suction device for carrying away particles of removed material.

  19. BepiColombo mission to Mercury: ISA accelerometer DeltaV measurements and the reaction wheels desaturation manoeuvres

    NASA Astrophysics Data System (ADS)

    Iafolla, Valerio; Lucchesi, David; Nozzoli, Sergio; Santoli, Francesco; Fiorenza, Emiliano; Peron, Roberto; Lefevre, Carlo; Reale, Andrea

    Mercury exploration is one of the most important challenges of modern planetary sciences. The results are a way to constrain the physics of the terrestrial planet formation and, at the end, of the whole solar system. The level of knowledge we can reach is strongly conditioned by the accuracy of the Radio Science Experiments (RSE) that will be performed using Earth—bound radar tracking stations. Such very ambitious objectives need an onboard accelerometer in or-der to measure and remove the strong, and subtle, nongravitational accelerations of the very severe radiation environment of the innermost planet of our solar system. The Italian Spring Accelerometer (ISA) has been selected to fly onboard the Mercury Planetary Orbiter (MPO) of the ESA space mission to Mercury denominated BepiColombo. The MPO will be a three-axis stabilized spacecraft and nadir pointing to Mercury center-of-mass. Such a pointing, needed for the very ambitious goals the mission, is reached thanks to the onboard reaction wheels, and it is also required during the unobserved (from Earth) arcs. The unavoidable manoeuvres of desaturation of the reaction wheels, which are necessary to remove the accumulated angular momentum, represent a clear reduction of the accuracy of the objectives of the ESA space mission. Indeed, during these manoeuvres the spacecraft thrusters are fired — to still guar-antee the pointing to the planet center-of-mass — and directly impact on the accuracy of the propagated state-vector of the satellite at the beginning of the subsequent observed arc. Their impact is quantified by their number, position along the orbit and, especially, in the uncertainty in the linear momentum transferred to the spacecraft. This presentation is devoted to prove the feasibility of the measurements and knowledge of the transferred momentum by the thruster thanks to the onboard ISA accelerometer. Such measurements will be an essential ingredient in order to preserve the accuracy of the Bepi

  20. System Wide Joint Position Sensor Fault Tolerance in Robot Systems Using Cartesian Accelerometers

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.; Juang, Jer-Nan

    1997-01-01

    Joint position sensors are necessary for most robot control systems. A single position sensor failure in a normal robot system can greatly degrade performance. This paper presents a method to obtain position information from Cartesian accelerometers without integration. Depending on the number and location of the accelerometers. the proposed system can tolerate the loss of multiple position sensors. A solution technique suitable for real-time implementation is presented. Simulations were conducted using 5 triaxial accelerometers to recover from the loss of up to 4 joint position sensors on a 7 degree of freedom robot moving in general three dimensional space. The simulations show good estimation performance using non-ideal accelerometer measurements.

  1. The location of the tibial accelerometer does influence impact acceleration parameters during running.

    PubMed

    Lucas-Cuevas, Angel Gabriel; Encarnación-Martínez, Alberto; Camacho-García, Andrés; Llana-Belloch, Salvador; Pérez-Soriano, Pedro

    2016-10-03

    Tibial accelerations have been associated with a number of running injuries. However, studies attaching the tibial accelerometer on the proximal section are as numerous as those attaching the accelerometer on the distal section. This study aimed to investigate whether accelerometer location influences acceleration parameters commonly reported in running literature. To fulfil this purpose, 30 athletes ran at 2.22, 2.78 and 3.33 m · s(-1) with three accelerometers attached with double-sided tape and tightened to the participants' tolerance on the forehead, the proximal section of the tibia and the distal section of the tibia. Time-domain (peak acceleration, shock attenuation) and frequency-domain parameters (peak frequency, peak power, signal magnitude and shock attenuation in both the low and high frequency ranges) were calculated for each of the tibial locations. The distal accelerometer registered greater tibial acceleration peak and shock attenuation compared to the proximal accelerometer. With respect to the frequency-domain analysis, the distal accelerometer provided greater values of all the low-frequency parameters, whereas no difference was observed for the high-frequency parameters. These findings suggest that the location of the tibial accelerometer does influence the acceleration signal parameters, and thus, researchers should carefully consider the location they choose to place the accelerometer so that equivalent comparisons across studies can be made.

  2. Self-calibration method of the bias of a space electrostatic accelerometer.

    PubMed

    Qu, Shao-Bo; Xia, Xiao-Mei; Bai, Yan-Zheng; Wu, Shu-Chao; Zhou, Ze-Bing

    2016-11-01

    The high precision space electrostatic accelerometer is an instrument to measure the non-gravitational forces acting on a spacecraft. It is one of the key payloads for satellite gravity measurements and space fundamental physics experiments. The measurement error of the accelerometer directly affects the precision of gravity field recovery for the earth. This paper analyzes the sources of the bias according to the operating principle and structural constitution of the space electrostatic accelerometer. Models of bias due to the asymmetry of the displacement sensing system, including the mechanical sensor head and the capacitance sensing circuit, and the asymmetry of the feedback control actuator circuit are described separately. According to the two models, a method of bias self-calibration by using only the accelerometer data is proposed, based on the feedback voltage data of the accelerometer before and after modulating the DC biasing voltage (Vb) applied on its test mass. Two types of accelerometer biases are evaluated separately using in-orbit measurement data of a space electrostatic accelerometer. Based on the preliminary analysis, the bias of the accelerometer onboard of an experiment satellite is evaluated to be around 10(-4) m/s(2), about 4 orders of magnitude greater than the noise limit. Finally, considering the two asymmetries, a comprehensive bias model is analyzed. A modified method to directly calibrate the accelerometer comprehensive bias is proposed.

  3. Self-calibration method of the bias of a space electrostatic accelerometer

    NASA Astrophysics Data System (ADS)

    Qu, Shao-Bo; Xia, Xiao-Mei; Bai, Yan-Zheng; Wu, Shu-Chao; Zhou, Ze-Bing

    2016-11-01

    The high precision space electrostatic accelerometer is an instrument to measure the non-gravitational forces acting on a spacecraft. It is one of the key payloads for satellite gravity measurements and space fundamental physics experiments. The measurement error of the accelerometer directly affects the precision of gravity field recovery for the earth. This paper analyzes the sources of the bias according to the operating principle and structural constitution of the space electrostatic accelerometer. Models of bias due to the asymmetry of the displacement sensing system, including the mechanical sensor head and the capacitance sensing circuit, and the asymmetry of the feedback control actuator circuit are described separately. According to the two models, a method of bias self-calibration by using only the accelerometer data is proposed, based on the feedback voltage data of the accelerometer before and after modulating the DC biasing voltage (Vb) applied on its test mass. Two types of accelerometer biases are evaluated separately using in-orbit measurement data of a space electrostatic accelerometer. Based on the preliminary analysis, the bias of the accelerometer onboard of an experiment satellite is evaluated to be around 10-4 m/s2, about 4 orders of magnitude greater than the noise limit. Finally, considering the two asymmetries, a comprehensive bias model is analyzed. A modified method to directly calibrate the accelerometer comprehensive bias is proposed.

  4. Testing Of Choiced Ceramics Cutting Tools At Irregular Interrupted Cut

    NASA Astrophysics Data System (ADS)

    Kyncl, Ladislav; Malotová, Šárka; Nováček, Pavel; Nicielnik, Henryk; Šoková, Dagmar; Hemžský, Pavel; Pitela, David; Holubjak, Jozef

    2015-12-01

    This article discusses the test of removable ceramic cutting inserts during machining irregular interrupted cut. Tests were performed on a lathe, with the preparation which simulated us the interrupted cut. By changing the number of plates mounted in a preparation it simulate us a regular or irregular interrupted cut. When with four plates it was regular interrupted cut, the remaining three variants were already irregular cut. It was examined whether it will have the irregular interrupted cutting effect on the insert and possibly how it will change life of inserts during irregular interrupted cut (variable delay between shocks).

  5. Equating accelerometer estimates among youth: the Rosetta Stone 2

    PubMed Central

    Brazendale, Keith; Beets, Michael W.; Bornstein, Daniel B.; Moore, Justin B.; Pate, Russell R.; Weaver, Robert G.; Falck, Ryan S.; Chandler, Jessica L.; Andersen, Lars B.; Anderssen, Sigmund A.; Cardon, Greet; Cooper, Ashley; Davey, Rachel; Froberg, Karsten; Hallal, Pedro C.; Janz, Kathleen F.; Kordas, Katarzyna; Kriemler, Susi; Puder, Jardena J.; Reilly, John J.; Salmon, Jo; Sardinha, Luis B.; Timperio, Anna; van Sluijs, Esther MF

    2017-01-01

    Objectives Different accelerometer cutpoints used by different researchers often yields vastly different estimates of moderate-to-vigorous intensity physical activity (MVPA). This is recognized as cutpoint non-equivalence (CNE), which reduces the ability to accurately compare youth MVPA across studies. The objective of this research is to develop a cutpoint conversion system that standardizes minutes of MVPA for six different sets of published cutpoints. Design Secondary data analysis Methods Data from the International Children’s Accelerometer Database (ICAD; Spring 2014) consisting of 43,112 Actigraph accelerometer data files from 21 worldwide studies (children 3-18 years, 61.5% female) were used to develop prediction equations for six sets of published cutpoints. Linear and non-linear modeling, using a leave one out cross-validation technique, was employed to develop equations to convert MVPA from one set of cutpoints into another. Bland Altman plots illustrate the agreement between actual MVPA and predicted MVPA values. Results Across the total sample, mean MVPA ranged from 29.7 MVPA min.d-1 (Puyau) to 126.1 MVPA min.d-1 (Freedson 3 METs). Across conversion equations, median absolute percent error was 12.6% (range: 1.3 to 30.1) and the proportion of variance explained ranged from 66.7% to 99.8%. Mean difference for the best performing prediction equation (VC from EV) was -0.110 min.d-1 (limits of agreement (LOA), -2.623 to 2.402). The mean difference for the worst performing prediction equation (FR3 from PY) was 34.76 min.d-1 (LOA, -60.392 to 129.910). Conclusions For six different sets of published cutpoints, the use of this equating system can assist individuals attempting to synthesize the growing body of literature on Actigraph, accelerometry-derived MVPA. PMID:25747468

  6. Interest of the MICROSTAR Accelerometer to improve the GRASP Mission.

    NASA Astrophysics Data System (ADS)

    Perrot, E.; Lebat, V.; Foulon, B.; Christophe, B.; Liorzou, F.; Huynh, P. A.

    2015-12-01

    The Geodetic Reference Antenna in Space (GRASP) is a micro satellite mission concept proposed by JPL to improve the definition of the Terrestrial Reference Frame (TRF). GRASP collocates GPS, SLR, VLBI, and DORIS sensors on a dedicated spacecraft in order to establish precise and stable ties between the key geodetic techniques used to define and disseminate the TRF. GRASP also offers a space-based reference antenna for the present and future Global Navigation Satellite Systems (GNSS). By taking advantage of the new testing possibilities offer by the catapult facility at the ZARM drop tower, the ONERA's space accelerometer team proposes an up-dated version, called MICROSTAR, of its ultra sensitive electrostatic accelerometers which have contributed to the success of the last Earth's gravity missions GRACE and GOCE. Built around a cubic proof-mass, it provides the 3 linear accelerations with a resolution better than 10-11 ms-2/Hz1/2 into a measurement bandwidth between 10-3 Hz and 0.1 Hz and the 3 angular accelerations about its 3 orthogonal axes with 5´10-10 rad.s-2/Hz1/2 resolution. Integrated at the centre of mass of the satellite, MICROSTAR improves the Precise Orbit Determination (POD) by accurate measurement of the non-gravitational force acting on the satellite. It offers also the possibility to calibrate the change in the position of the satellite center of mass with an accuracy better than 100 μm as demonstrated in the GRACE mission. Assuming a sufficiently rigid structure between the antennas and the accelerometer, its data can participate to reach the mission objective of 1 mm precision for the TRF position.

  7. Piezoelectric Shaker Development for High Frequency Calibration of Accelerometers

    SciTech Connect

    Payne, Bev; Harper, Kari K.; Vogl, Gregory W.

    2010-05-28

    Calibration of vibration transducers requires sinusoidal motion over a wide frequency range with low distortion and low cross-axial motion. Piezoelectric shakers are well suited to generate such motion and are suitable for use with laser interferometric methods at frequencies of 3 kHz and above. An advantage of piezoelectric shakers is the higher achievable accelerations and displacement amplitudes as compared to electro-dynamic (ED) shakers. Typical commercial ED calibration shakers produce maximum accelerations from 100 m/s{sup 2} to 500 m/s{sup 2}. Very large ED shakers may produce somewhat higher accelerations but require large amplifiers and expensive cooling systems to dissipate heat. Due to the limitations in maximum accelerations by ED shakers at frequencies above 5 kHz, the amplitudes of the generated sinusoidal displacement are frequently below the resolution of laser interferometers used in primary calibration methods. This limits the usefulness of ED shakers in interferometric based calibrations at higher frequencies.Small piezoelectric shakers provide much higher acceleration and displacement amplitudes for frequencies above 5 kHz, making these shakers very useful for accelerometer calibrations employing laser interferometric measurements, as will be shown in this paper. These piezoelectric shakers have been developed and used at NIST for many years for high frequency calibration of accelerometers. This paper documents the construction and performance of a new version of these shakers developed at NIST for the calibration of accelerometers over the range of 3 kHz to 30 kHz and possibly higher. Examples of typical calibration results are also given.

  8. MEMS capacitive accelerometer-based middle ear microphone.

    PubMed

    Young, Darrin J; Zurcher, Mark A; Semaan, Maroun; Megerian, Cliff A; Ko, Wen H

    2012-12-01

    The design, implementation, and characterization of a microelectromechanical systems (MEMS) capacitive accelerometer-based middle ear microphone are presented in this paper. The microphone is intended for middle ear hearing aids as well as future fully implantable cochlear prosthesis. Human temporal bones acoustic response characterization results are used to derive the accelerometer design requirements. The prototype accelerometer is fabricated in a commercial silicon-on-insulator (SOI) MEMS process. The sensor occupies a sensing area of 1 mm × 1 mm with a chip area of 2 mm × 2.4 mm and is interfaced with a custom-designed low-noise electronic IC chip over a flexible substrate. The packaged sensor unit occupies an area of 2.5 mm × 6.2 mm with a weight of 25 mg. The sensor unit attached to umbo can detect a sound pressure level (SPL) of 60 dB at 500 Hz, 35 dB at 2 kHz, and 57 dB at 8 kHz. An improved sound detection limit of 34-dB SPL at 150 Hz and 24-dB SPL at 500 Hz can be expected by employing start-of-the-art MEMS fabrication technology, which results in an articulation index of approximately 0.76. Further micro/nanofabrication technology advancement is needed to enhance the microphone sensitivity for improved understanding of normal conversational speech.

  9. Self-powered In-plane Accelerometer Using Triboelectric Mechanism

    NASA Astrophysics Data System (ADS)

    Gupta, Rahul Kumar; Dhakar, Lokesh; Lee, Chengkuo

    2016-11-01

    This paper presents a self-powered triboelectric based accelerometer to detect wide range of in-plane acceleration utilizing the triboelectric mechanism. The freestanding sliding mode was utilized to realize the in-plane sensing. The fabricated device consists of soft polymer spring which displays wide detection range from ±1g to ±6g (g = 9.8m/s2) in x and y directions with sensitivity of 21mV/(g). The proposed device can be utilized for self-powered shock sensing in various future applications.

  10. Material for Fast Cutting

    NASA Technical Reports Server (NTRS)

    Perez, A.

    1986-01-01

    New material for cutting tools increases productivity of machining processes. Material, called Iscanite (or equivalent), based on silicon nitride contains more than 90 percent silicon. Combines impact resistance close to that of coated carbides with heat and wear resistance close to those of aluminum oxide ceramics. Material used for cutting on old or new machine tools and makes it possible to exploit fully power and speed of machine.

  11. The BepiColombo mission to Mercury: Reaction wheels desaturation manoeuvres and the ISA accelerometer Δ V⇒ measurements

    NASA Astrophysics Data System (ADS)

    Iafolla, V.; Lucchesi, D.-M.; Nozzoli, S.; Santoli, F.

    2011-01-01

    The Mercury Planetary Orbiter will be a three-axis stabilized spacecraft and nadir pointing to Mercury center-of-mass. The pointing accuracy, needed for the very ambitious goals of the ESA space mission to Mercury denominated BepiColombo, is reached thanks to the onboard reaction wheels, and it is also required during the unobserved arcs. The unavoidable manoeuvres of desaturation of the reaction wheels, which are necessary to remove the accumulated angular momentum, represent a clear reduction of the accuracy of the objectives of the ESA space mission. Indeed, these manoeuvres are performed through the spacecraft thrusters and directly impact the accuracy of the propagated state-vector of the satellite at the beginning of the subsequent observed arc. Their impact is quantified by their number, position along the orbit and, especially, in the uncertainty in the linear momentum transferred to the spacecraft. The present paper is devoted to prove the feasibility of the speed variation measurements produced by the thruster thanks to the onboard accelerometer, ISA. Therefore, such measurements may be an essential ingredient in order to preserve the accuracy of the BepiColombo Radio Science Experiments and of other onboard instruments pointing accuracy, as is the case of BELA. This additional capability of ISA strengthens once more the key role of the accelerometer in the BepiColombo mission to Mercury.

  12. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Mark Pickell; Len Volk; Mike Volk; Evren Ozbayoglu; Lei Zhou

    2002-04-30

    This is the third quarterly progress report for Year 3 of the ACTS Project. It includes a review of progress made in: (1) Flow Loop construction and development and (2) research tasks during the period of time between Jan. 1, 2002 and Mar. 31, 2002. This report presents a review of progress on the following specific tasks: (a) Design and development of an Advanced Cuttings Transport Facility (Task 3: Addition of a Cuttings Injection/Separation System), (b) Research project (Task 6): ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)'', (c) Research project (Task 9b): ''Study of Foam Flow Behavior Under EPET Conditions'', (d) Research project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions'', (e) Research on three instrumentation tasks to measure: Cuttings concentration and distribution in a flowing slurry (Task 11), Foam texture while transporting cuttings. (Task 12), and Viscosity of Foam under EPET (Task 9b); (f) Development of a Safety program for the ACTS Flow Loop, progress on a comprehensive safety review of all flow-loop components and operational procedures. (Task 1S); and (g) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members.

  13. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Mark Pickell; Len Volk; Mike Volk; Lei Zhou; Zhu Chen; Crystal Redden; Aimee Washington

    2003-01-30

    This is the second quarterly progress report for Year-4 of the ACTS Project. It includes a review of progress made in: (1) Flow Loop construction and development and (2) research tasks during the period of time between October 1, 2002 and December 30, 2002. This report presents a review of progress on the following specific tasks. (a) Design and development of an Advanced Cuttings Transport Facility Task 3: Addition of a Cuttings Injection/Separation System, Task 4: Addition of a Pipe Rotation System. (b) New research project (Task 9b): ''Development of a Foam Generator/Viscometer for Elevated Pressure and Elevated Temperature (EPET) Conditions''. (d) Research project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions''. (e) Research on three instrumentation tasks to measure: Cuttings concentration and distribution in a flowing slurry (Task 11), Foam texture while transporting cuttings. (Task 12), and Viscosity of Foam under EPET (Task 9b). (f) New Research project (Task 13): ''Study of Cuttings Transport with Foam under Elevated Pressure and Temperature Conditions''. (g) Development of a Safety program for the ACTS Flow Loop. Progress on a comprehensive safety review of all flow-loop components and operational procedures. (Task 1S). (h) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members.

  14. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Mark Pickell; Len Volk; Mike Volk; Affonso Lourenco; Evren Ozbayoglu; Lei Zhou

    2002-01-30

    This is the second quarterly progress report for Year 3 of the ACTS project. It includes a review of progress made in: (1) Flow Loop development and (2) research tasks during the period of time between Oct 1, 2001 and Dec. 31, 2001. This report presents a review of progress on the following specific tasks: (a) Design and development of an Advanced Cuttings Transport Facility (Task 3: Addition of a Cuttings Injection/Collection System), (b) Research project (Task 6): ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)'', (c) Research project (Task 9): ''Study of Foam Flow Behavior Under EPET Conditions'', (d) Research project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions'', (e) Research on instrumentation tasks to measure: Cuttings concentration and distribution in a flowing slurry (Task 11), and Foam properties while transporting cuttings. (Task 12), (f) Development of a Safety program for the ACTS Flow Loop. Progress on a comprehensive safety review of all flow-loop components and operational procedures. (Task 1S). (g) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members.

  15. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Mark Pickell; Len Volk; Mike Volk; Barkim Demirdal; Affonso Lourenco; Evren Ozbayoglu; Paco Vieira; Lei Zhou

    2000-01-30

    This is the second quarterly progress report for Year 2 of the ACTS project. It includes a review of progress made in Flow Loop development and research during the period of time between Oct 1, 2000 and December 31, 2000. This report presents a review of progress on the following specific tasks: (a) Design and development of an Advanced Cuttings Transport Facility (Task 2: Addition of a foam generation and breaker system), (b) Research project (Task 6): ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)'', (c) Research project (Task 7): ''Study of Cuttings Transport with Aerated Muds Under LPAT Conditions (Joint Project with TUDRP)'', (d) Research project (Task 8): ''Study of Flow of Synthetic Drilling Fluids Under Elevated Pressure and Temperature Conditions'', (e) Research project (Task 9): ''Study of Foam Flow Behavior Under EPET Conditions'', (f) Research project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions'', (g) Research on instrumentation tasks to measure: Cuttings concentration and distribution in a flowing slurry (Task 11), and Foam properties while transporting cuttings. (Task 12), (h) Development of a Safety program for the ACTS Flow Loop. Progress on a comprehensive safety review of all flow-loop components and operational procedures. (Task 1S). (i) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members. The tasks Completed During This Quarter are Task 7 and Task 8.

  16. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Mark Pickell; Len Volk; Mike Volk; Evren Ozbayoglu; Lei Zhou

    2002-07-30

    This is the fourth quarterly progress report for Year-3 of the ACTS Project. It includes a review of progress made in: (1) Flow Loop construction and development and (2) research tasks during the period of time between April 1, 2002 and June 30, 2002. This report presents a review of progress on the following specific tasks: (a) Design and development of an Advanced Cuttings Transport Facility (Task 3: Addition of a Cuttings Injection/Separation System), (b) Research project (Task 6): ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)''; (c) Research project (Task 9b): ''Study of Foam Flow Behavior Under EPET Conditions''; (d) Research project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions''; (e) Research on three instrumentation tasks to measure: Cuttings concentration and distribution in a flowing slurry (Task 11), Foam texture while transporting cuttings. (Task 12), and Viscosity of Foam under EPET (Task 9b); (f) Development of a Safety program for the ACTS Flow Loop. Progress on a comprehensive safety review of all flow-loop components and operational procedures. (Task 1S); (g) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members.

  17. Accelerometer Load Profiles for Basketball-Specific Drills in Elite Players

    PubMed Central

    Schelling, Xavi; Torres, Lorena

    2016-01-01

    The purpose of this study was to quantify the workload during basketball-specific drills measured through microtechnology. Twelve professional male basketball players from the Spanish 1st Division were monitored over a 4-week period. Data were collected from 16 sessions, for a total of 95 ± 33 drills per player. Workload data (Acceleration load; AL) were obtained from a tri-axial accelerometer at 100Hz sampling frequency, and were expressed over time (AL.min-1). Comparisons among training drills (i.e., 2v2, 3v3, 4v4, and 5v5) were assessed via standardized mean differences. Full-court 3v3 and 5v5 showed the highest physical demand (AL.min-1: 18.7 ± 4.1 and 17.9 ± 4.6, respectively) compared with other traditional balanced basketball drills such as 2v2 and 4v4 (14.6 ± 2.8 and 13.8±2.5, respectively). The AL.min-1 on half-court showed trivial-to-moderate differences with a likely increase of ~10-20% in 2v2 drill compared with any other formats. This study provides insight into the specific requirements of a range of exercises typically performed in basketball sessions. The use of accelerometer data is presented as a useful tool in assessing the workload. Key points Full-court 3v3 and 5v5 showed the highest external workload. The smaller the player, the higher the raw acceleration load. Systematic monitoring during training and competition would likely improve training prescription and periodization. PMID:27928203

  18. Dynamic Fluid in a Porous Transducer-Based Angular Accelerometer

    PubMed Central

    Cheng, Siyuan; Fu, Mengyin; Wang, Meiling; Ming, Li; Fu, Huijin; Wang, Tonglei

    2017-01-01

    This paper presents a theoretical model of the dynamics of liquid flow in an angular accelerometer comprising a porous transducer in a circular tube of liquid. Wave speed and dynamic permeability of the transducer are considered to describe the relation between angular acceleration and the differential pressure on the transducer. The permeability and streaming potential coupling coefficient of the transducer are determined in the experiments, and special prototypes are utilized to validate the theoretical model in both the frequency and time domains. The model is applied to analyze the influence of structural parameters on the frequency response and the transient response of the fluidic system. It is shown that the radius of the circular tube and the wave speed affect the low frequency gain, as well as the bandwidth of the sensor. The hydrodynamic resistance of the transducer and the cross-section radius of the circular tube can be used to control the transient performance. The proposed model provides the basic techniques to achieve the optimization of the angular accelerometer together with the methodology to control the wave speed and the hydrodynamic resistance of the transducer. PMID:28230793

  19. Microelectromechanical Resonant Accelerometer Designed with a High Sensitivity

    PubMed Central

    Zhang, Jing; Su, Yan; Shi, Qin; Qiu, An-Ping

    2015-01-01

    This paper describes the design and experimental evaluation of a silicon micro-machined resonant accelerometer (SMRA). This type of accelerometer works on the principle that a proof mass under acceleration applies force to two double-ended tuning fork (DETF) resonators, and the frequency output of two DETFs exhibits a differential shift. The dies of an SMRA are fabricated using silicon-on-insulator (SOI) processing and wafer-level vacuum packaging. This research aims to design a high-sensitivity SMRA because a high sensitivity allows for the acceleration signal to be easily demodulated by frequency counting techniques and decreases the noise level. This study applies the energy-consumed concept and the Nelder-Mead algorithm in the SMRA to address the design issues and further increase its sensitivity. Using this novel method, the sensitivity of the SMRA has been increased by 66.1%, which attributes to both the re-designed DETF and the reduced energy loss on the micro-lever. The results of both the closed-form and finite-element analyses are described and are in agreement with one another. A resonant frequency of approximately 22 kHz, a frequency sensitivity of over 250 Hz per g, a one-hour bias stability of 55 μg, a bias repeatability (1σ) of 48 μg and the bias-instability of 4.8 μg have been achieved. PMID:26633425

  20. ISA accelerometer: fundamental support for the exploration of planet Mercury

    NASA Astrophysics Data System (ADS)

    Iafolla, Valerio; Fiorenza, Emiliano; Lefevre, Carlo; Nozzoli, Sergio; Peron, Roberto; Reale, Andrea; Santoli, Francesco

    2010-05-01

    The development of BepiColombo mission is proceeding, in view of the launch, foreseen for 2014. This mission will perform a thorough study of the planet Mercury and its environment. An important set of scientific objectives is constituted by the so-called Radio Science Experiments (RSE), which will study the gravitational field and rotation of the planet, and will perform very precise tests of general relativity theory. In order to reach the required level of accuracy in recovering the relevant parameters, the data coming from the high-sensitivity ISA (Italian Spring Accelerometer) instrument onboard the Mercury Planetary Orbiter (MPO) will be used: this will be the first time for a deep-space probe. Following a brief description of the mission and RSE, the instrument and its wide capabilities will be reviewed. The focus will be in particular on the updated error budget, operational procedures and extended use of the instrument in the various parts of the RSE. It will be also described the procedure for on-ground calibration of the accelerometer.

  1. Free fall tests of the accelerometers of the MICROSCOPE mission

    NASA Astrophysics Data System (ADS)

    Liorzou, F.; Boulanger, D.; Rodrigues, M.; Touboul, P.; Selig, H.

    2014-09-01

    The MICROSCOPE mission is fully dedicated to the in-orbit test of the Universality of free fall, the so-called Weak Equivalence Principle (WEP), with an expected accuracy better than 10-15. The test principle consists in comparing the accelerations of two proof masses of different composition in the Earth gravitational field. The payload embarks two pairs of test-masses made of Platinum Rhodium and Titanium alloys at the core of two dedicated coaxial electrostatic accelerometers. These instruments are under qualification for a launch in 2016. Their operations are only possible in microgravity environment which makes its validation on ground a real issue. In Europe, only the drop tower of the ZARM Institute provides a facility for experiments under conditions of weightlessness and offers the experimental conditions to verify the correct functioning of the MICROSCOPE payload. The height of the tower limits the “free fall” experiment period to 4.72 s. Under this strong constraint, the demonstration of the capability to control the test masses of the two coaxial electrostatic accelerometers is challenging. This paper describes the complete experimental set up and in which condition the test has been performed, then an analysis of a drop result is given with its interpretations.

  2. Technique for Determining Bridge Displacement Response Using MEMS Accelerometers

    PubMed Central

    Sekiya, Hidehiko; Kimura, Kentaro; Miki, Chitoshi

    2016-01-01

    In bridge maintenance, particularly with regard to fatigue damage in steel bridges, it is important to determine the displacement response of the entire bridge under a live load as well as that of each member. Knowing the displacement response enables the identification of dynamic deformations that can cause stresses and ultimately lead to damage and thus also allows the undertaking of appropriate countermeasures. In theory, the displacement response can be calculated from the double integration of the measured acceleration. However, data measured by an accelerometer include measurement errors caused by the limitations of the analog-to-digital conversion process and sensor noise. These errors distort the double integration results. Furthermore, as bridges in service are constantly vibrating because of passing vehicles, estimating the boundary conditions for the numerical integration is difficult. To address these problems, this paper proposes a method for determining the displacement of a bridge in service from its acceleration based on its free vibration. To verify the effectiveness of the proposed method, field measurements were conducted using nine different accelerometers. Based on the results of these measurements, the proposed method was found to be highly accurate in comparison with the reference displacement obtained using a contact displacement gauge. PMID:26907287

  3. Surface Micromachined Silicon Carbide Accelerometers for Gas Turbine Applications

    NASA Technical Reports Server (NTRS)

    DeAnna, Russell G.

    1998-01-01

    A finite-element analysis of possible silicon carbide (SIC) folded-beam, lateral-resonating accelerometers is presented. Results include stiffness coefficients, acceleration sensitivities, resonant frequency versus temperature, and proof-mass displacements due to centripetal acceleration of a blade-mounted sensor. The surface micromachined devices, which are similar to the Analog Devices Inc., (Norwood, MA) air-bag crash detector, are etched from 2-pm thick, 3C-SiC films grown at 1600 K using atmospheric pressure chemical vapor deposition (APCVD). The substrate is a 500 gm-thick, (100) silicon wafer. Polysilicon or silicon dioxide is used as a sacrificial layer. The finite element analysis includes temperature-dependent properties, shape change due to volume expansion, and thermal stress caused by differential thermal expansion of the materials. The finite-element results are compared to experimental results for a SiC device of similar, but not identical, geometry. Along with changes in mechanical design, blade-mounted sensors would require on-chip circuitry to cancel displacements due to centripetal acceleration and improve sensitivity and bandwidth. These findings may result in better accelerometer designs for this application.

  4. Shock margin testing of a one-axis MEMS accelerometer.

    SciTech Connect

    Parson, Ted Blair; Tanner, Danelle Mary; Buchheit, Thomas Edward

    2008-07-01

    Shock testing was performed on a selected commercial-off-the-shelf - MicroElectroMechanical System (COTS-MEMS) accelerometer to determine the margin between the published absolute maximum rating for shock and the 'measured' level where failures are observed. The purpose of this testing is to provide baseline data for isolating failure mechanisms under shock and environmental loading in a representative device used or under consideration for use within systems and assemblies of the DOD/DOE weapons complex. The specific device chosen for this study was the AD22280 model of the ADXL78 MEMS Accelerometer manufactured by Analog Devices Inc. This study focuses only on the shock loading response of the device and provides the necessary data for adding influence of environmental exposure to the reliability of this class of devices. The published absolute maximum rating for acceleration in any axis was 4000 G for this device powered or unpowered. Results from this study showed first failures at 8000 G indicating a margin of error of two. Higher shock level testing indicated that an in-plane, but off-axis acceleration was more damaging than one in the sense direction.

  5. Airbag accelerometer with a simple switched-capacitor readout ASIC

    NASA Astrophysics Data System (ADS)

    Tsugai, Masahiro; Hirata, Yoshiaki; Tanimoto, Koji; Usami, Teruo; Araki, Toru; Otani, Hiroshi

    1997-09-01

    A bulk micromachined capacitive accelerometer for airbag applications based on (110) silicon anisotropic KOH etching is presented. The sensor is a two-chip accelerometer that consists of a glass-silicon-glass stacked sense element and an interface ASIC containing an impedance converter for capacitance detection, an EPROM and DACs for digital trimming, and a self-test feature for diagnosis. A simple switched-capacitor readout circuit with DC offset error cancellation scheme is proposed as the impedance converter. The dependence of narrow gap etching, surface roughness, and uniformity of the groove depth on the KOH concentration are also investigated for the fabrication of the device, and it is shown that the etch rate of the plane intrinsically controls the depth of the narrow gap with a KOH concentration of over 30 wt. percent, and smooth surface and uniformity of groove depth are obtained at 40 wt. percent KOH. The nonlinearity of the output is about 1.5 percent FS. The temperature coefficient of sensitivity and the off-axis sensitivity are 150 ppm/degree C and 2 percent respectively. The dimensions of the sensor are 10.3 X 10.3 X 3 mm.

  6. Engineering Implications of Rotational Sensitivity of Translational Accelerometers

    NASA Astrophysics Data System (ADS)

    Boroschek, R. L.

    2006-12-01

    Several studies have indicated that nominal linear translational accelerometers are strongly sensitive to rotation motions, especially around their horizontal axis. It has been theoretically and experimentally demonstrated that this situation affects the acceleration record and severely limits appropriate velocity and displacement determination. More importantly the common believe that filtering long periods signals could "clean" the acceleration record from this unwanted effect has been shown inadequate by the author this abstract and collaborators using experimental testing. Rotational effects are still present on filtered records unless the complete frequency bandwidth that composes the rotation motion is filtered out. In civil engineering structures rotations are nearly always present. Typical examples are foundation rocking, beam bending, floor slab deformation and overall rotation of structures due to relative large loads or damage. Two real cases were rotation of a relative flexible structure strongly influence the linear accelerometer responses are presented and later experimentally reproduce in a shake table controlled situation. The first one corresponds to a bridge with a contiguous 383 meter simple supported beam rested on rubber bearing that suffered the rotational related distortions due to the passing of a heavy truck at the end of a seismic event. The second event corresponds to the vibration recording of vertical motions on an industrial bridge that is exposed to forced vibration of a large motor. Both examples indicate that in certain conditions motion records from structural instruments are subjected to distortions effects that could make acceleration, velocity and displacement (temporarily or permanent) measurements not reliable.

  7. Applying macro design tools to the design of MEMS accelerometers

    SciTech Connect

    Davies, B.R.; Rodgers, M.S.; Montague, S.

    1998-02-01

    This paper describes the design of two different surface micromachined (MEMS) accelerometers and the use of design and analysis tools intended for macro sized devices. This work leverages a process for integrating both the micromechanical structures and microelectronics circuitry of a MEMS accelerometer on the same chip. In this process, the mechanical components of the sensor are first fabricated at the bottom of a trench etched into the wafer substrate. The trench is then filled with oxide and sealed to protect the mechanical components during subsequent microelectronics processing. The wafer surface is then planarized in preparation for CMOS processing. Next, the CMOS electronics are fabricated and the mechanical structures are released. The mechanical structure of each sensor consists of two polysilicon plate masses suspended by multiple springs (cantilevered beam structures) over corresponding polysilicon plates fixed to the substrate to form two parallel plate capacitors. One polysilicon plate mass is suspended using compliant springs forming a variable capacitor. The other polysilicon plate mass is suspended using very stiff springs acting as a fixed capacitor. Acceleration is measured by comparing the variable capacitance with the fixed capacitance during acceleration.

  8. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Mengjiao Yu; Ramadan Ahmed; Mark Pickell; Len Volk; Lei Zhou; Zhu Chen; Aimee Washington; Crystal Redden

    2003-09-30

    The Quarter began with installing the new drill pipe, hooking up the new hydraulic power unit, completing the pipe rotation system (Task 4 has been completed), and making the SWACO choke operational. Detailed design and procurement work is proceeding on a system to elevate the drill-string section. The prototype Foam Generator Cell has been completed by Temco and delivered. Work is currently underway to calibrate the system. Literature review and preliminary model development for cuttings transportation with polymer foam under EPET conditions are in progress. Preparations for preliminary cuttings transport experiments with polymer foam have been completed. Two nuclear densitometers were re-calibrated. Drill pipe rotation system was tested up to 250 RPM. Water flow tests were conducted while rotating the drill pipe up to 100 RPM. The accuracy of weight measurements for cuttings in the annulus was evaluated. Additional modifications of the cuttings collection system are being considered in order to obtain the desired accurate measurement of cuttings weight in the annular test section. Cutting transport experiments with aerated fluids are being conducted at EPET, and analyses of the collected data are in progress. The printed circuit board is functioning with acceptable noise level to measure cuttings concentration at static condition using ultrasonic method. We were able to conduct several tests using a standard low pass filter to eliminate high frequency noise. We tested to verify that we can distinguish between different depths of sand in a static bed of sand. We tested with water, air and a mix of the two mediums. Major modifications to the DTF have almost been completed. A stop-flow cell is being designed for the DTF, the ACTF and Foam Generator/Viscometer which will allow us to capture bubble images without the need for ultra fast shutter speeds or microsecond flash system.

  9. Calibration and validation of individual GOCE accelerometers by precise orbit determination

    NASA Astrophysics Data System (ADS)

    Visser, P. N. A. M.; IJssel, J. A. A. van den

    2016-01-01

    The European Space Agency Gravity field and steady-state Ocean Circular Explorer (GOCE) carries a gradiometer consisting of three pairs of accelerometers in an orthogonal triad. Precise GOCE science orbit solutions (PSO), which are based on satellite-to-satellite tracking observations by the Global Positioning System and which are claimed to be at the few cm precision level, can be used to calibrate and validate the observations taken by the accelerometers. This has been done for each individual accelerometer by a dynamic orbit fit of the time series of position co-ordinates from the PSOs, where the accelerometer observations represent the non-gravitational accelerations. Since the accelerometers do not coincide with the center of mass of the GOCE satellite, the observations have to be corrected for rotational and gravity gradient terms. This is not required when using the so-called common-mode accelerometer observations, provided the center of the gradiometer coincides with the GOCE center of mass. Dynamic orbit fits based on these common-mode accelerations therefore served as reference. It is shown that for all individual accelerometers, similar dynamic orbit fits can be obtained provided the above-mentioned corrections are made. In addition, accelerometer bias estimates are obtained that are consistent with offsets in the gravity gradients that are derived from the GOCE gradiometer observations.

  10. Assessing Physical Activity in Children with Asthma: Convergent Validity between Accelerometer and Electronic Diary Data

    ERIC Educational Resources Information Center

    Floro, Josh N.; Dunton, Genevieve F.; Delfino, Ralph J.

    2009-01-01

    Convergent validity of accelerometer and electronic diary physical activity data was assessed in children with asthma. Sixty-two participants, ages 9-18 years, wore an accelerometer and reported their physical activity level in quarter-hour segments every 2 hr using the Ambulatory Diary Assessment (ADA). Moderate validity was found between…

  11. A New Z-axis Resonant Micro-Accelerometer Based on Electrostatic Stiffness

    PubMed Central

    Yang, Bo; Wang, Xingjun; Dai, Bo; Liu, Xiaojun

    2015-01-01

    Presented in the paper is the design, the simulation, the fabrication and the experiment of a new z-axis resonant accelerometer based on the electrostatic stiffness. The new z-axis resonant micro-accelerometer, which consists of a torsional accelerometer and two plane resonators, decouples the sensing movement of the accelerometer from the oscillation of the plane resonators by electrostatic stiffness, which will improve the performance. The new structure and the sensitive theory of the acceleration are illuminated, and the equation of the scale factor is deduced under ideal conditions firstly. The Ansys simulation is implemented to verify the basic principle of the torsional accelerometer and the plane resonator individually. The structure simulation results prove that the effective frequency of the torsional accelerometer and the plane resonator are 0.66 kHz and 13.3 kHz, respectively. Then, the new structure is fabricated by the standard three-mask deep dry silicon on glass (DDSOG) process and encapsulated by parallel seam welding. Finally, the detecting and control circuits are designed to achieve the closed-loop self-oscillation, to trace the natural frequency of resonator and to measure the system frequency. Experimental results show that the new z-axis resonant accelerometer has a scale factor of 31.65 Hz/g, a bias stability of 727 μg and a dynamic range of over 10 g, which proves that the new z-axis resonant micro-accelerometer is practicable. PMID:25569748

  12. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Mark Pickell; Len Volk; Mike Volk; Barkim Demirdal; Affonso Lourenco; Evren Ozbayoglu; Paco Vieira

    2000-10-30

    This is the first quarterly progress report for Year 2 of the ACTS project. It includes a review of progress made in Flow Loop development and research during the period of time between July 14, 2000 and September 30, 2000. This report presents information on the following specific tasks: (a) Progress in Advanced Cuttings Transport Facility design and development (Task 2), (b) Progress on research project (Task 8): ''Study of Flow of Synthetic Drilling Fluids Under Elevated Pressure and Temperature Conditions'', (c) Progress on research project (Task 6): ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)'', (d) Progress on research project (Task 7): ''Study of Cuttings Transport with Aerated Muds Under LPAT Conditions (Joint Project with TUDRP)'', (e) Progress on research project (Task 9): ''Study of Foam Flow Behavior Under EPET Conditions'', (f) Initiate research on project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions'', (g) Progress on instrumentation tasks to measure: Cuttings concentration and distribution (Tasks 11), and Foam properties (Task 12), (h) Initiate a comprehensive safety review of all flow-loop components and operational procedures. Since the previous Task 1 has been completed, we will now designate this new task as: (Task 1S). (i) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members.

  13. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Mark Pickell; Len Volk, Mike Volk; Lei Zhou; Zhu Chen; Crystal Redden; Aimee Washington

    2002-10-30

    This is the first quarterly progress report for Year-4 of the ACTS Project. It includes a review of progress made in: (1) Flow Loop construction and development and (2) research tasks during the period of time between July 1, 2002 and Sept. 30, 2002. This report presents a review of progress on the following specific tasks: (a) Design and development of an Advanced Cuttings Transport Facility Task 3: Addition of a Cuttings Injection/Separation System, Task 4: Addition of a Pipe Rotation System, (b) New Research project (Task 9b): ''Development of a Foam Generator/Viscometer for Elevated Pressure and Elevated Temperature (EPET) Conditions'', (d) Research project (Task 10): ''Study of Cuttings Transport with Aerated Mud Under Elevated Pressure and Temperature Conditions'', (e) Research on three instrumentation tasks to measure: Cuttings concentration and distribution in a flowing slurry (Task 11), Foam texture while transporting cuttings (Task 12), Viscosity of Foam under EPET (Task 9b). (f) Development of a Safety program for the ACTS Flow Loop. Progress on a comprehensive safety review of all flow-loop components and operational procedures. (Task 1S). (g) Activities towards technology transfer and developing contacts with Petroleum and service company members, and increasing the number of JIP members.

  14. High shock, high frequency characteristics of a mechanical isolator for a piezoresistive accelerometer

    SciTech Connect

    Bateman, V.I.; Brown, F.A.; Davie, N.T.

    1995-07-01

    A mechanical isolator has been developed for a piezoresistive accelerometer. The purpose of the isolator is to mitigate high frequency shocks before they reach the accelerometer because the high frequency shocks may cause the accelerometer to resonate. Since the accelerometer is undamped, it often breaks when it resonates. The mechanical isolator was developed in response to impact test requirements for a variety of structures at Sandia National Laboratories. An Extended Technical Assistance Program with the accelerometer manufacturer has resulted in a commercial isolator that will be available to the general public. This mechanical isolator has ten times the bandwidth of any other commercial isolator and has acceptable frequency domain performance from DC to 10 kHz ({plus_minus} 10%) over a temperature range of -65{degrees}F to +185{degrees}F as demonstrated in this paper.

  15. Cutting Guide for Fibrous Sheets

    NASA Technical Reports Server (NTRS)

    Warren, A., D.

    1985-01-01

    Tool facilitates repetitive cutting of fibrous sheets. Flexible aluminum tape allows metal strips folded back on themselves, exposing fresh material for cutting. More than one strip folded back, and cutting width therefore increased in multiples of strip width. Developed for cutting strips of alumina-fiber matting, tool also used on such materials as felts, textiles, and sheet metals.

  16. POD improvements of GALILEO satellites through the measurement of their non-gravitational accelerations by means of an onboard accelerometer

    NASA Astrophysics Data System (ADS)

    Peron, Roberto; Lucchesi, David M.; Santoli, Francesco; Iafolla, Valerio; Fiorenza, Emiliano; Lefevre, Carlo; Lucente, Marco; Magnafico, Carmelo; Kalarus, Maciej; Zielinski, Janusz

    2016-04-01

    The Precise Orbit Determination (POD) of the satellites of the Global Navigation Satellite Systems (GNSS) represents the basic prerequisite in order to provide refined ephemerides for their orbit, aimed at providing a precise and accurate positioning on the Earth. An important factor that impacts negatively in the POD of these satellites is the limited modeling of the accelerations produced by the non-gravitational accelerations. These, indeed, are subtle and generally complex to model properly, especially in the case of a complex in shape spacecraft, with solar panels and antennae for microwave link and the mutual shadowing effects among the many surfaces involved. We have to notice that their modeling has an important impact in the determination of a number of geophysical parameters of interest, such as stations coordinates, Earth's geocenter and orientation parameters. In the case of GNSS satellites, the main NGP acceleration is the one produced by the direct solar radiation pressure, with non-negligible contributions due to Earth's albedo, thermal effects and power radiated by the antennae. The models developed so far for these perturbative effects have shown many limits, as pointed out in the literature. Currently, the models developed for the NGPs are mainly based on empirical blind models (with the goal of absorb unknowns quantities) and more recently with the use of wing-box models, that try to provide a finite-elements approach to the modeling. The European Space Agency (ESA) - in the context of the development of the GALILEO constellation, and especially in view of the next generation of GALILEO spacecraft - besides being interested in possible improvements of the NGPs models, is also envisaging the use of an onboard accelerometer to directly measure them in order to improve the POD of each spacecraft of the constellation. We have been involved in this study by means of a proposal to ESA denominated GALileo and ACcelerometry (GALAC) led by the Space

  17. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Ergun Kuru; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Len Volk; Mark Pickell; Evren Ozbayoglu; Barkim Demirdal; Paco Vieira; Affonso Lourenco

    1999-10-15

    This report includes a review of the progress made in ACTF Flow Loop development and research during 90 days pre-award period (May 15-July 14, 1999) and the following three months after the project approval date (July15-October 15, 1999) The report presents information on the following specific subjects; (a) Progress in Advanced Cuttings Transport Facility design and development, (b) Progress report on the research project ''Study of Flow of Synthetic Drilling Fluids Under Elevated Pressure and Temperature Conditions'', (c) Progress report on the research project ''Study of Cuttings Transport with Foam Under LPAT Conditions (Joint Project with TUDRP)'', (d) Progress report on the research project ''Study of Cuttings Transport with Aerated Muds Under LPAT Conditions (Joint Project with TUDRP)'', (e) Progress report on the research project ''Study of Foam Flow Behavior Under EPET Conditions'', (f) Progress report on the instrumentation tasks (Tasks 11 and 12) (g) Activities towards technology transfer and developing contacts with oil and service company members.

  18. Cutting assembly. [Patent application

    DOEpatents

    Treuhaft, M.B.; Oser, M.S.

    1981-06-25

    A mining auger comprises a cutting head carried at one end of a tubular shaft and a plurality of wall segments which in a first position thereof are disposed side by side around said shaft and in a second position thereof are disposed oblique to said shaft. A vane projects outwardly from each wall segment. When the wall segments are in their first position, the vanes together form a substantially continuous helical wall. A cutter is mounted on the peripheral edge of each of the vanes. When the wall segments are in their second position, the cutters on the vanes are disposed radially outward from the perimeter of the cutting head.

  19. Atmospheric structure from Mars Reconnaissance Orbiter accelerometer measurements

    NASA Astrophysics Data System (ADS)

    Keating, G.; Bougher, S.; Theriot, M.; Zurek, R.; Blanchard, R.; Tolson, R.; Murphy, J.

    Designed for aerobraking, Mars Reconnaissance Orbiter (MRO) launched on August 12, 2005, achieved Mars Orbital Insertion (MOI), March 10, 2006. Atmospheric density decreases exponentially with increasing height. By small propulsive adjustments of the apoapsis orbital velocity, periapsis altitude is fine tuned to the density surface that will safely use the atmosphere of Mars to aerobrake over 500 orbits. MRO periapsis precesses from the South Pole at 6pm LST to near the equator at 3am LST. Meanwhile, apoapsis is brought dramatically from ˜40,000km at MOI to 460 km at aerobraking completion (ABX) mid September 2006. After ABX, a few small propulsive maneuvers will establish the Primary Science Orbit (PSO), which without aerobraking would have required an additional 400 kg of fuel. Each of the 500 plus aerobraking orbits provides a vertical structure and distribution of density, scale heights, and temperatures, along the orbital path, providing key in situ insight into various upper atmosphere (> 100 km) processes. One of the major questions for scientists studying Mars is: "Where did the water go?" Honeywell's substantially improved electronics package for its IMU (QA-2000 accelerometer, gyro, electronics) maximized accelerometer sensitivities at the requests of The George Washington University, JPL, and Lockheed Martin. The improved accelerometer sensitivities allowed density measurements to exceed 200km, at least 40 km higher than with Mars Odyssey (MO). This extends vertical structures from MRO into the neutral lower exosphere, a region where various processes may allow atmospheric gasses to escape. Over the eons, water may have been lost in both the lower atmosphere and the upper atmosphere, thus the water balance throughout the entire atmosphere from subsurface to exosphere may be equally critical. Comparisons of data from Mars Global Surveyor (MGS), MO and MRO will help characterize key temporal and spatial cycles including: polar vortices, winter polar

  20. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Stefan Miska; Troy Reed; Ergun Kuru

    2004-09-30

    The Advanced Cuttings Transport Study (ACTS) was a 5-year JIP project undertaken at the University of Tulsa (TU). The project was sponsored by the U.S. Department of Energy (DOE) and JIP member companies. The objectives of the project were: (1) to develop and construct a new research facility that would allow three-phase (gas, liquid and cuttings) flow experiments under ambient and EPET (elevated pressure and temperature) conditions, and at different angle of inclinations and drill pipe rotation speeds; (2) to conduct experiments and develop a data base for the industry and academia; and (3) to develop mechanistic models for optimization of drilling hydraulics and cuttings transport. This project consisted of research studies, flow loop construction and instrumentation development. Following a one-year period for basic flow loop construction, a proposal was submitted by TU to the DOE for a five-year project that was organized in such a manner as to provide a logical progression of research experiments as well as additions to the basic flow loop. The flow loop additions and improvements included: (1) elevated temperature capability; (2) two-phase (gas and liquid, foam etc.) capability; (3) cuttings injection and removal system; (4) drill pipe rotation system; and (5) drilling section elevation system. In parallel with the flow loop construction, hydraulics and cuttings transport studies were preformed using drilling foams and aerated muds. In addition, hydraulics and rheology of synthetic drilling fluids were investigated. The studies were performed under ambient and EPET conditions. The effects of temperature and pressure on the hydraulics and cuttings transport were investigated. Mechanistic models were developed to predict frictional pressure loss and cuttings transport in horizontal and near-horizontal configurations. Model predictions were compared with the measured data. Predominantly, model predictions show satisfactory agreements with the measured data. As a

  1. Optimal Cut Points for Quality of Life Questionnaire-Core 30 (QLQ-C30) Scales: Utility for Clinical Trials and Updates of Prognostic Systems in Advanced Hepatocellular Carcinoma

    PubMed Central

    Bonnetain, Franck; Barbare, Jean-Claude; Bouché, Olivier; Dahan, Laetitia; Paoletti, Xavier; Filleron, Thomas

    2015-01-01

    Background. Health-related quality of life (QoL) has been validated as a prognostic factor for cancer patients; however, to be used in routine practice, QoL scores must be dichotomized. Cutoff points are usually based on arbitrary percentile values. We aimed to identify optimal cutoff points for six QoL scales and to quantify their added utility in the performance of four prognostic classifications in patients with hepatocellular carcinoma (HCC). Methods. We reanalyzed data of 271 patients with advanced HCC recruited between July 2002 and October 2003 from 79 institutions in France in the CHOC trial, designed to assess the efficacy of long-acting octreotide. QoL was assessed with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (QLQ-C30). The scores ranged from 0 to 100. Identification of optimal cutoff points was based on the method of Faraggi and Simon [Stat Med 1996;15:2203–2213]. Improvement in the performance of prognostic classifications was studied with Harrell’s C-index, the net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Results. We found that optimal cutoff points were 50 for global health, 58.33 for physical functioning, 66.67 for role functioning, 66.67 for fatigue, 0 for dyspnea, and 33.33 for diarrhea. The addition of QoL and clinical factors improved the performance of all four prognostic classifications, with improvement in the range of 0.02–0.09 for the C-index, 0.24–0.78 for 3-month NRI, and 0.02–0.10 for IDI. Conclusion. These cutoff values for QoL scales can be useful to identify HCC patients with very poor prognosis and thus improve design of clinical trials and treatment adjustment for these patients. PMID:25542450

  2. Cutting Cakes Carefully

    ERIC Educational Resources Information Center

    Hill, Theodore P.; Morrison, Kent E.

    2010-01-01

    This paper surveys the fascinating mathematics of fair division, and provides a suite of examples using basic ideas from algebra, calculus, and probability which can be used to examine and test new and sometimes complex mathematical theories and claims involving fair division. Conversely, the classical cut-and-choose and moving-knife algorithms…

  3. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Ergun Kuru; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Len Volk; Mark Pickell; Mike Volk; Barkim Demirdal; Affonso Lourenco; Evren Ozbayoglu; Paco Vieira; Neelima Godugu; Sri Suresh Kumar Thiroveedhula

    2000-04-30

    ACTS flow loop is now operational under elevated pressure and temperature. Currently, experiments with water under pressure and temperature are being conducted. Based on the analysis of Fann 70 data, empirical correlations defining the shear stress as a function of temperature, pressure and the shear rate have been developed for Petrobras synthetic drilling fluids. PVT equipment has been modified for testing Synthetic drilling fluids. Initial calibration tests have been conducted by using water. Currently, the base oil of the Petrobras synthetic drilling fluid is being tested. Foam flow experiments have been conducted. Currently, more experiments are being conducted while data are being analyzed to characterize the rheology of the foam. Cuttings transport experiments have been conducted using air, water and cuttings. Preliminary results have shown that it may not be possible to avoid cuttings bed deposition under any practical combination of air and water flow rates. Foam stability analyses have been conducted. Effects of salt and oil concentration on the foam stability have been investigated. A software for controlling the data sampling and data storage during cuttings monitoring process have been developed.

  4. Kids Who Cut.

    ERIC Educational Resources Information Center

    Coy, Doris Rhea; Simpson, Chris

    2002-01-01

    Regardless of whether it is cutting, burning or some other form of self-harm, self-injury is a serious problem requiring serious solutions. This article reviews the various types of self-harm, descriptions of self-mutilators, common myths about self-mutilation, and effective treatment methods. (GCP)

  5. Think before You Cut

    ERIC Educational Resources Information Center

    Pettifor, Ann

    2010-01-01

    With the main political parties set on reducing public spending, one might be forgiven for supposing that "savage" cuts are the only way forward. However, the author believes there are alternatives, and that is why public education about the financial system is so important. Today, UK is trying to clear up a mess--a mess made by the…

  6. Classroom Cut Ups

    ERIC Educational Resources Information Center

    Lord, Stacy

    2011-01-01

    Discovering identity can be a lifelong challenge for some people, while others seem to figure it out right away. During the middle school years, finding one's identity can be a daunting task. Most students will spend a considerable amount of time during these middle years looking for it. This lesson on cut-paper self-portraits lets students delve…

  7. Electron beam cutting

    DOEpatents

    Mochel, Margaret E.; Humphreys, Colin J.

    1985-04-02

    A method for the cutting of holes 20 Angstroms in diameter, or lines 20 Angstroms wide in a material having positive ionic conduction by the use of a focused electron probe is described. The holes and lines are stable under ambient conditions.

  8. Electron beam cutting

    DOEpatents

    Mochel, M.E.; Humphreys, C.J.

    1985-04-02

    A method for the cutting of holes 20 Angstroms in diameter, or lines 20 Angstroms wide in a material having positive ionic conduction by the use of a focused electron probe is described. The holes and lines are stable under ambient conditions. 2 figs.

  9. Slice&Dice: Recognizing Food Preparation Activities Using Embedded Accelerometers

    NASA Astrophysics Data System (ADS)

    Pham, Cuong; Olivier, Patrick

    Within the context of an endeavor to provide situated support for people with cognitive impairments in the kitchen, we developed and evaluated classifiers for recognizing 11 actions involved in food preparation. Data was collected from 20 lay subjects using four specially designed kitchen utensils incorporating embedded 3-axis accelerometers. Subjects were asked to prepare a mixed salad in our laboratory-based instrumented kitchen environment. Video of each subject's food preparation activities were independently annotated by three different coders. Several classifiers were trained and tested using these features. With an overall accuracy of 82.9% our investigation demonstrated that a broad set of food preparation actions can be reliably recognized using sensors embedded in kitchen utensils.

  10. Accelerometer-Based Event Detector for Low-Power Applications

    PubMed Central

    Smidla, József; Simon, Gyula

    2013-01-01

    In this paper, an adaptive, autocovariance-based event detection algorithm is proposed, which can be used with micro-electro-mechanical systems (MEMS) accelerometer sensors to build inexpensive and power efficient event detectors. The algorithm works well with low signal-to-noise ratio input signals, and its computational complexity is very low, allowing its utilization on inexpensive low-end embedded sensor devices. The proposed algorithm decreases its energy consumption by lowering its duty cycle, as much as the event to be detected allows it. The performance of the algorithm is tested and compared to the conventional filter-based approach. The comparison was performed in an application where illegal entering of vehicles into restricted areas was detected. PMID:24135991

  11. A silicon micromachined piezoresistive accelerometer for health and condition monitoring

    NASA Technical Reports Server (NTRS)

    Walsh, Kevin M.; Henderson, H. Thurman

    1990-01-01

    Silicon micromachining etching techniques were utilized to batch-fabricate hundreds of general purpose microaccelerometers on a single silicon substrate. Piezoresistive sensing elements were aligned to the back-side patterns using an IR mask aligner and then diffused into the areas of maximum stress. Capping of the two-arm cantilever beam structure was achieved using a combination of electrostatic bonding and low temperature glass films. Overrange protection, critical damping, and overall protection from the outside environment are achieved by controlling the cavity depths of the top and bottom covers. Temperature compensation, amplification, and filtering are performed by a companion LSI chip that is interfaced to the accelerometer by conventional wire-bonding techniques.

  12. Vehicle Maneuver Detection with Accelerometer-Based Classification

    PubMed Central

    Cervantes-Villanueva, Javier; Carrillo-Zapata, Daniel; Terroso-Saenz, Fernando; Valdes-Vela, Mercedes; Skarmeta, Antonio F.

    2016-01-01

    In the mobile computing era, smartphones have become instrumental tools to develop innovative mobile context-aware systems. In that sense, their usage in the vehicular domain eases the development of novel and personal transportation solutions. In this frame, the present work introduces an innovative mechanism to perceive the current kinematic state of a vehicle on the basis of the accelerometer data from a smartphone mounted in the vehicle. Unlike previous proposals, the introduced architecture targets the computational limitations of such devices to carry out the detection process following an incremental approach. For its realization, we have evaluated different classification algorithms to act as agents within the architecture. Finally, our approach has been tested with a real-world dataset collected by means of the ad hoc mobile application developed. PMID:27690058

  13. GOCE Accelerometers Data Revisited: Stability And Detector Noise

    NASA Astrophysics Data System (ADS)

    Berge, J.; Christophe, B.; Foulon, B.

    2013-12-01

    We report on our analyses of Gravity field and steady- state Ocean Circulation Explorer (GOCE) data aiming to characterize the stability and the noise of GOCE's ac- celerometers. We first measure science and detector co- herence signals, which allow us to infer the role of the accelerometers Digital Voltage Amplifiers and measure- ment chanel in the overall quadratic factor and scale fac- tor; we show that their temporal stability is as low as ex- pected. We then investigate the effect of the aliasing of high frequency detector's noise on the measured noise, in an attempt to explain why the measured noise is higher than originally expected. We find that although this alias- ing explains part of the higher noise, it does not account for the total of the difference seen between the expected and the measured noise.

  14. Concept of an Opto-electronic Accelerometer System (OAS)

    NASA Technical Reports Server (NTRS)

    Kunkel, B.; Keller, K.; Lutz, R.

    1987-01-01

    An accelerometer based on a spring-suspended reference mass and its precise relative motion measurement by means of 3 two-dimensional position sensitive detectors (PSD) is described. A breadboard model achieves a resolution (longterm linearity) of 25 nm in one direction. Due to the physical principle of the PSD, the second layer is slightly less sensitive than the top layer; accordingly for gravity gradient detection the more sensitive layer is selected for the Z/X component detection. At 10 Hz sampling rate an acceleration gradient of under 10 to the minus 12th power g (i.e., 0.01 E or 0.001 Gal/km) is considered to be detectable.

  15. Concept of an Opto-electronic Accelerometer System (OAS)

    NASA Astrophysics Data System (ADS)

    Kunkel, B.; Keller, K.; Lutz, R.

    1987-10-01

    An accelerometer based on a spring-suspended reference mass and its precise relative motion measurement by means of 3 two-dimensional position sensitive detectors (PSD) is described. A breadboard model achieves a resolution (longterm linearity) of 25 nm in one direction. Due to the physical principle of the PSD, the second layer is slightly less sensitive than the top layer; accordingly for gravity gradient detection the more sensitive layer is selected for the Z/X component detection. At 10 Hz sampling rate an acceleration gradient of under 10 to the minus 12th power g (i.e., 0.01 E or 0.001 Gal/km) is considered to be detectable.

  16. Monolithic CMOS-MEMS integration for high-g accelerometers

    NASA Astrophysics Data System (ADS)

    Narasimhan, Vinayak; Li, Holden; Tan, Chuan Seng

    2014-10-01

    This paper highlights work-in-progress towards the conceptualization, simulation, fabrication and initial testing of a silicon-germanium (SiGe) integrated CMOS-MEMS high-g accelerometer for military, munition, fuze and shock measurement applications. Developed on IMEC's SiGe MEMS platform, the MEMS offers a dynamic range of 5,000 g and a bandwidth of 12 kHz. The low noise readout circuit adopts a chopper-stabilization technique implementing the CMOS through the TSMC 0.18 µm process. The device structure employs a fully differential split comb-drive set up with two sets of stators and a rotor all driven separately. Dummy structures acting as protective over-range stops were designed to protect the active components when under impacts well above the designed dynamic range.

  17. ISLES: Probing Extra Dimensions Using a Superconducting Accelerometer

    NASA Technical Reports Server (NTRS)

    Paik, Ho Jung; Moody, M. Vol; Prieto-Gortcheva, Violeta A.

    2003-01-01

    In string theories, extra dimensions must be compactified. The possibility that gravity can have large radii of compactification leads to a violation of the inverse square law at submillimeter distances. The objective of ISLES is to perform a null test of Newton s law in space with a resolution of one part in 10(exp 5) or better at 100 microns. The experiment will be cooled to less than or equal to 2 K, which permits superconducting magnetic levitation of the test masses. To minimize Newtonian errors, ISLES employs a near null source, a circular disk of large diameter-to-thickness ratio. Two test masses, also disk-shaped, are suspended on the two sides of the source mass at a nominal distance of 100 microns. The signal is detected by a superconducting differential accelerometer. A ground test apparatus is under construction.

  18. 6. SEAWARD VIEW OF BOAT LANDING CUT INTO ROCK, ALSO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. SEAWARD VIEW OF BOAT LANDING CUT INTO ROCK, ALSO SHOWING CEMENT POURED ATOP TUNNEL. - Mile Rock Tunnel, Under Forty-eighth Avenue from Cabrillo Street to San Francisco Bay at Point Lobos, San Francisco, San Francisco County, CA

  19. Quasi-Static Calibration Method of a High-g Accelerometer.

    PubMed

    Wang, Yan; Fan, Jinbiao; Zu, Jing; Xu, Peng

    2017-02-20

    To solve the problem of resonance during quasi-static calibration of high-g accelerometers, we deduce the relationship between the minimum excitation pulse width and the resonant frequency of the calibrated accelerometer according to the second-order mathematical model of the accelerometer, and improve the quasi-static calibration theory. We establish a quasi-static calibration testing system, which uses a gas gun to generate high-g acceleration signals, and apply a laser interferometer to reproduce the impact acceleration. These signals are used to drive the calibrated accelerometer. By comparing the excitation acceleration signal and the output responses of the calibrated accelerometer to the excitation signals, the impact sensitivity of the calibrated accelerometer is obtained. As indicated by the calibration test results, this calibration system produces excitation acceleration signals with a pulse width of less than 1000 μs, and realize the quasi-static calibration of high-g accelerometers with a resonant frequency above 20 kHz when the calibration error was 3%.

  20. A brief test of the Hewlett-Packard MEMS seismic accelerometer

    USGS Publications Warehouse

    Homeijer, Brian D.; Milligan, Donald J.; Hutt, Charles R.

    2014-01-01

    Testing was performed on a prototype of Hewlett-Packard (HP) Micro-Electro-Mechanical Systems (MEMS) seismic accelerometer at the U.S. Geological Survey’s Albuquerque Seismological Laboratory. This prototype was built using discrete electronic components. The self-noise level was measured during low seismic background conditions and found to be 9.8 ng/√Hz at periods below 0.2 s (frequencies above 5 Hz). The six-second microseism noise was also discernible. The HP MEMS accelerometer was compared to a Geotech Model GS-13 reference seismometer during seismic noise and signal levels well above the self-noise of the accelerometer. Matching power spectral densities (corrected for accelerometer and seismometer responses to represent true ground motion) indicated that the HP MEMS accelerometer has a flat (constant) response to acceleration from 0.0125 Hz to at least 62.5 Hz. Tilt calibrations of the HP MEMS accelerometer verified that the flat response to acceleration extends to 0 Hz. Future development of the HP MEMS accelerometer includes replacing the discreet electronic boards with a low power application-specific integrated circuit (ASIC) and increasing the dynamic range of the sensor to detect strong motion signals above one gravitational acceleration, while maintaining the self-noise observed during these tests.

  1. A triaxial accelerometer monkey algorithm for optimal sensor placement in structural health monitoring

    NASA Astrophysics Data System (ADS)

    Jia, Jingqing; Feng, Shuo; Liu, Wei

    2015-06-01

    Optimal sensor placement (OSP) technique is a vital part of the field of structural health monitoring (SHM). Triaxial accelerometers have been widely used in the SHM of large-scale structures in recent years. Triaxial accelerometers must be placed in such a way that all of the important dynamic information is obtained. At the same time, the sensor configuration must be optimal, so that the test resources are conserved. The recommended practice is to select proper degrees of freedom (DOF) based upon several criteria and the triaxial accelerometers are placed at the nodes corresponding to these DOFs. This results in non-optimal placement of many accelerometers. A ‘triaxial accelerometer monkey algorithm’ (TAMA) is presented in this paper to solve OSP problems of triaxial accelerometers. The EFI3 measurement theory is modified and involved in the objective function to make it more adaptable in the OSP technique of triaxial accelerometers. A method of calculating the threshold value based on probability theory is proposed to improve the healthy rate of monkeys in a troop generation process. Meanwhile, the processes of harmony ladder climb and scanning watch jump are proposed and given in detail. Finally, Xinghai NO.1 Bridge in Dalian is implemented to demonstrate the effectiveness of TAMA. The final results obtained by TAMA are compared with those of the original monkey algorithm and EFI3 measurement, which show that TAMA can improve computational efficiency and get a better sensor configuration.

  2. Quasi-Static Calibration Method of a High-g Accelerometer

    PubMed Central

    Wang, Yan; Fan, Jinbiao; Zu, Jing; Xu, Peng

    2017-01-01

    To solve the problem of resonance during quasi-static calibration of high-g accelerometers, we deduce the relationship between the minimum excitation pulse width and the resonant frequency of the calibrated accelerometer according to the second-order mathematical model of the accelerometer, and improve the quasi-static calibration theory. We establish a quasi-static calibration testing system, which uses a gas gun to generate high-g acceleration signals, and apply a laser interferometer to reproduce the impact acceleration. These signals are used to drive the calibrated accelerometer. By comparing the excitation acceleration signal and the output responses of the calibrated accelerometer to the excitation signals, the impact sensitivity of the calibrated accelerometer is obtained. As indicated by the calibration test results, this calibration system produces excitation acceleration signals with a pulse width of less than 1000 μs, and realize the quasi-static calibration of high-g accelerometers with a resonant frequency above 20 kHz when the calibration error was 3%. PMID:28230743

  3. Agreement rates for sleep/wake judgments obtained via accelerometer and sleep diary: a comparison.

    PubMed

    Kawada, Tomoyuki

    2008-11-01

    Agreement rates for waking and sleeping obtained via sleep diary and accelerometer were evaluated, to compare the two methods. Sleep/wake data for consecutive days and nights were surveyed in 119 healthy university students. Accelerometer sleep/wake judgments obeyed the standard algorithm. Agreement rates for waking and sleeping according to accelerometer versus sleep diary, respectively, were calculated. Sleep diary data were set as a baseline. Seventy-six subjects (63.9%), 22 to 32 years of age, presented perfect data for the analysis. The mean sleep times, in minutes, judged by sleep diary and by accelerometer, were 482.3 and 629.6, respectively. The mean percentages and standard deviations of agreement on wake and sleep were 77.5% (SD = 10.2) and 86.1% (SD = 6.2), respectively. There was a significant negative relationship between the agreement rates for wake and sleep (r = -.482, p < .01). The accelerometer showed some measurement failure during waking, presumably because of the decrease in body movement. Sleep diary data during daytime appear to be more valid for detecting a sleep/wake cycle than are accelerometer data. In contrast, nocturnal sleep diary data might be supplemented by the use of an accelerometer as long as participants do not have insomnia.

  4. Cutting fluid study for single crystal silicon

    SciTech Connect

    Chargin, D.

    1998-05-05

    An empirical study was conducted to evaluate cutting fluids for Single Point Diamond Turning (SPDT) of single crystal silicon. The pH of distilled waster was adjusted with various additives the examine the effect of pH on cutting operations. Fluids which seemed to promote ductile cutting appeared to increase tool wear as well, an undesirable tradeoff. High Ph sodium hydroxide solutions showed promise for further research, as they yielded the best combination of reduced tool wear and good surface finish in the ductile regime. Negative rake tools were verified to improve the surface finish, but the negative rake tools used in the experiments also showed much higher wear than conventional 0{degree} rake tools. Effects of crystallographic orientation on SPDT, such as star patterns of fracture damage forming near the center of the samples, were observed to decrease with lower feedrates. Silicon chips were observed and photographed, indicative of a ductile materials removal process.

  5. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Mark Pickell; Len Volk; Mike Volk; Lei Zhou; Zhu Chen; Crystal Redden; Aimee Washington

    2003-04-30

    Experiments on the flow loop are continuing. Improvements to the software for data acquisition are being made as additional experience with three-phase flow is gained. Modifications are being made to the Cuttings Injection System in order to improve control and the precision of cuttings injection. The design details for a drill-pipe Rotation System have been completed. A US Patent was filed on October 28, 2002 for a new design for an instrument that can generate a variety of foams under elevated pressures and temperatures and then transfer the test foam to a viscometer for measurements of viscosity. Theoretical analyses of cuttings transport phenomena based on a layered model is under development. Calibrations of two nuclear densitometers have been completed. Baseline tests have been run to determine wall roughness in the 4 different tests sections (i.e. 2-in, 3-in, 4-in pipes and 5.76-in by 3.5-in annulus) of the flow loop. Tests have also been conducted with aerated fluids at EPET conditions. Preliminary experiments on the two candidate aqueous foam formulations were conducted which included rheological tests of the base fluid and foam stability reports. These were conducted after acceptance of the proposal on the Study of Cuttings Transport with Foam Under Elevated Pressure and Elevated Temperature Conditions. Preparation of a test matrix for cuttings-transport experiments with foam in the ACTF is also under way. A controller for instrumentation to measure cuttings concentration and distribution has been designed that can control four transceivers at a time. A prototype of the control circuit board was built and tested. Tests showed that there was a problem with radiated noise. AN improved circuit board was designed and sent to an external expert to verify the new design. The new board is being fabricated and will first be tested with static water and gravel in an annulus at elevated temperatures. A series of viscometer tests to measure foam properties have

  6. The effect of cutting conditions on power inputs when machining

    NASA Astrophysics Data System (ADS)

    Petrushin, S. I.; Gruby, S. V.; Nosirsoda, Sh C.

    2016-08-01

    Any technological process involving modification of material properties or product form necessitates consumption of a certain power amount. When developing new technologies one should take into account the benefits of their implementation vs. arising power inputs. It is revealed that procedures of edge cutting machining are the most energy-efficient amongst the present day forming procedures such as physical and technical methods including electrochemical, electroerosion, ultrasound, and laser processing, rapid prototyping technologies etc, such as physical and technical methods including electrochemical, electroerosion, ultrasound, and laser processing, rapid prototyping technologies etc. An expanded formula for calculation of power inputs is deduced, which takes into consideration the mode of cutting together with the tip radius, the form of the replaceable multifaceted insert and its wear. Having taken as an example cutting of graphite iron by the assembled cutting tools with replaceable multifaceted inserts the authors point at better power efficiency of high feeding cutting in comparison with high-speed cutting.

  7. Self Diagnostic Accelerometer for Mission Critical Health Monitoring of Aircraft and Spacecraft Engines

    NASA Technical Reports Server (NTRS)

    Lekki, John; Tokars, Roger; Jaros, Dave; Riggs, M. Terrence; Evans, Kenneth P.; Gyekenyesi, Andrew

    2009-01-01

    A self diagnostic accelerometer system has been shown to be sensitive to multiple failure modes of charge mode accelerometers. These failures include sensor structural damage, an electrical open circuit and most importantly sensor detachment. In this paper, experimental work that was performed to determine the capabilities of a self diagnostic accelerometer system while operating in the presence of various levels of mechanical noise, emulating real world conditions, is presented. The results show that the system can successfully conduct a self diagnostic routine under these conditions.

  8. Use of a laser doppler vibrometer for high frequency accelerometer characterizations

    SciTech Connect

    Bateman, V.I.; Hansche, B.D.; Solomon, O.M.

    1995-12-31

    A laser doppler vibrometer (LDV) is being used for high frequency characterizations of accelerometers at Sandia National Laboratories (SNL). A LDV with high frequency (up to 1.5 MHz) and high velocity (10 M/s) capability was purchased from a commercial source and has been certified by the Primary Electrical Standards Department at SNL. The method used for this certification and the certification results are presented. Use of the LDV for characterization of accelerometers at high frequencies and of accelerometer sensitivity to cross-axis shocks on a Hopkinson bar apparatus is discussed.

  9. Material Behavior At The Extreme Cutting Edge In Bandsawing

    SciTech Connect

    Sarwar, Mohammed; Haider, Julfikar; Persson, Martin; Hellbergh, Haakan

    2011-01-17

    In recent years, bandsawing has been widely accepted as a favourite option for metal cutting off operations where the accuracy of cut, good surface finish, low kerf loss, long tool life and high material removal rate are required. Material removal by multipoint cutting tools such as bandsaw is a complex mechanism owing to the geometry of the bandsaw tooth (e.g., limited gullet size, tooth setting etc.) and the layer of material removed or undeformed chip thickness or depth of cut (5 {mu}m-50 {mu}m) being smaller than or equal to the cutting edge radius (5 {mu}m-15 {mu}m). This situation can lead to inefficient material removal in bandsawing. Most of the research work are concentrated on the mechanics of material removal by single point cutting tool such as lathe tool. However, such efforts are very limited in multipoint cutting tools such as in bandsaw. This paper presents the fundamental understanding of the material behaviour at the extreme cutting edge of bandsaw tooth, which would help in designing and manufacturing of blades with higher cutting performance and life. ''High Speed Photography'' has been carried out to analyse the material removal process at the extreme cutting edge of bandsaw tooth. Geometric model of chip formation mechanisms based on the evidences found during ''High Speed Photography'' and ''Quick Stop'' process is presented. Wear modes and mechanism in bimetal and carbide tipped bandsaw teeth are also presented.

  10. Material Behavior At The Extreme Cutting Edge In Bandsawing

    NASA Astrophysics Data System (ADS)

    Sarwar, Mohammed; Haider, Julfikar; Persson, Martin; Hellbergh, Hâkan

    2011-01-01

    In recent years, bandsawing has been widely accepted as a favourite option for metal cutting off operations where the accuracy of cut, good surface finish, low kerf loss, long tool life and high material removal rate are required. Material removal by multipoint cutting tools such as bandsaw is a complex mechanism owing to the geometry of the bandsaw tooth (e.g., limited gullet size, tooth setting etc.) and the layer of material removed or undeformed chip thickness or depth of cut (5 μm-50 μm) being smaller than or equal to the cutting edge radius (5 μm-15 μm). This situation can lead to inefficient material removal in bandsawing. Most of the research work are concentrated on the mechanics of material removal by single point cutting tool such as lathe tool. However, such efforts are very limited in multipoint cutting tools such as in bandsaw. This paper presents the fundamental understanding of the material behaviour at the extreme cutting edge of bandsaw tooth, which would help in designing and manufacturing of blades with higher cutting performance and life. "High Speed Photography" has been carried out to analyse the material removal process at the extreme cutting edge of bandsaw tooth. Geometric model of chip formation mechanisms based on the evidences found during "High Speed Photography" and "Quick Stop" process is presented. Wear modes and mechanism in bimetal and carbide tipped bandsaw teeth are also presented.

  11. Laser cutting nozzle

    DOEpatents

    Ramos, Terry J.

    1984-01-01

    A laser cutting nozzle for use with a laser cutting apparatus directing a focused beam to a spot on a work piece. The nozzle has a cylindrical body with a conical tip which together have a conically shaped hollow interior with the apex at a small aperture through the tip. The conical hollow interior is shaped to match the profile of the laser beam, at full beamwidth, which passes through the nozzle to the work piece. A plurality of gas inlet holes extend through the body to the hollow interior and are oriented to produce a swirling flow of gas coaxially through the nozzle and out the aperture, aligned with the laser beam, to the work piece. BACKGROUND OF THE INVENTION

  12. Laser cutting nozzle

    DOEpatents

    Ramos, T.J.

    1982-09-30

    A laser cutting nozzle for use with a laser cutting apparatus directing a focused beam to a spot on a work piece. The nozzle has a cylindrical body with a conical tip which together have a conically shaped hollow interior with the apex at a small aperture through the tip. The conical hollow interior is shaped to match the profile of the laser beam, at full beamwidth, which passes through the nozzle to the work piece. A plurality of gas inlet holes extend through the body to the hollow interior and are oriented to produce a swirling flow of gas coaxially through the nozzle and out the aperture, aligned with the laser beam, to the work piece.

  13. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Ergun Kuru; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Gerald Kane; Mark Pickell; Len Volk; Mike Volk; Barkim Demirdal; Affonso Lourenco; Evren Ozbayoglu; Paco Vieira; Neelima Godugu

    2000-07-30

    ACTS flow loop is now operational under elevated pressure and temperature. Currently, experiments with synthetic based drilling fluids under pressure and temperature are being conducted. Based on the analysis of Fann 70 data, empirical correlations defining the shear stress as a function of temperature, pressure and the shear rate have been developed for Petrobras synthetic drilling fluids. PVT equipment has been modified for testing Synthetic oil base drilling fluids. PVT tests with Petrobras Synthetic base mud have been conducted and results are being analyzed Foam flow experiments have been conducted and the analysis of the data has been carried out to characterize the rheology of the foam. Comparison of pressure loss prediction from the available foam hydraulic models and the test results has been made. Cuttings transport experiments in horizontal annulus section have been conducted using air, water and cuttings. Currently, cuttings transport tests in inclined test section are being conducted. Foam PVT analysis tests have been conducted. Foam stability experiments have also been conducted. Effects of salt and oil concentration on the foam stability have been investigated. Design of ACTS flow loop modification for foam and aerated mud flow has been completed. A flow loop operation procedure for conducting foam flow experiments under EPET conditions has been prepared Design of the lab-scale flow loop for dynamic foam characterization and cuttings monitoring instrumentation tests has been completed. The construction of the test loop is underway. As part of the technology transport efforts, Advisory Board Meeting with ACTS-JIP industry members has been organized on May 13, 2000.

  14. Manual bamboo cutting tool.

    PubMed

    Bezerra, Mariana Pereira; Correia, Walter Franklin Marques; da Costa Campos, Fabio Ferreira

    2012-01-01

    The paper presents the development of a cutting tool guide, specifically for the harvest of bamboo. The development was made based on precepts of eco-design and ergonomics, for prioritizing the physical health of the operator and the maintenance of the environment, as well as meet specific requirements of bamboo. The main goal is to spread the use of bamboo as construction material, handicrafts, among others, from a handy, easy assembly and material available tool.

  15. Vortex cutting in superconductors

    NASA Astrophysics Data System (ADS)

    Vlasko-Vlasov, Vitalii K.; Koshelev, Alexei E.; Glatz, Andreas; Welp, Ulrich; Kwok, Wai-K.

    2015-03-01

    Unlike illusive magnetic field lines in vacuum, magnetic vortices in superconductors are real physical strings, which interact with the sample surface, crystal structure defects, and with each other. We address the complex and poorly understood process of vortex cutting via a comprehensive set of magneto-optic experiments which allow us to visualize vortex patterns at magnetization of a nearly twin-free YBCO crystal by crossing magnetic fields of different orientations. We observe a pronounced anisotropy in the flux dynamics under crossing fields and the filamentation of induced supercurrents associated with the staircase vortex structure expected in layered cuprates, flux cutting effects, and angular vortex instabilities predicted for anisotropic superconductors. At some field angles, we find formation of the vortex domains following a type-I phase transition in the vortex state accompanied by an abrupt change in the vortex orientation. To clarify the vortex cutting scenario we performed time-dependent Ginzburg-Landau simulations, which confirmed formation of sharp vortex fronts observed in the experiment and revealed a left-handed helical instability responsible for the rotation of vortices. This work was supported by the U.S. Department of Energy, Office of Science, Materials Sciences and Engineering Division.

  16. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Troy Reed; Stefan Miska; Nicholas Takach; Kaveh Ashenayi; Mark Pickell; Len Volk; Mike Volk; Lei Zhou; Zhu Chen; Crystal Redden; Aimee Washington

    2003-07-30

    This Quarter has been divided between running experiments and the installation of the drill-pipe rotation system. In addition, valves and piping were relocated, and three viewports were installed. Detailed design work is proceeding on a system to elevate the drill-string section. Design of the first prototype version of a Foam Generator has been finalized, and fabrication is underway. This will be used to determine the relationship between surface roughness and ''slip'' of foams at solid boundaries. Additional cups and rotors are being machined with different surface roughness. Some experiments on cuttings transport with aerated fluids have been conducted at EPET. Theoretical modeling of cuttings transport with aerated fluids is proceeding. The development of theoretical models to predict frictional pressure losses of flowing foam is in progress. The new board design for instrumentation to measure cuttings concentration is now functioning with an acceptable noise level. The ultrasonic sensors are stable up to 190 F. Static tests with sand in an annulus indicate that the system is able to distinguish between different sand concentrations. Viscometer tests with foam, generated by the Dynamic Test Facility (DTF), are continuing.

  17. Reagan Administration Prepares Budget Cuts.

    ERIC Educational Resources Information Center

    Norman, Colin

    1981-01-01

    Describes tentative federal budget cuts affecting science education in the National Science Foundation, National Aeronautics and Space Administration, Department of Energy, National Institutes of Health, and the specific areas these budget cuts will affect. (DS)

  18. Point-to-Point Multicast Communications Protocol

    NASA Technical Reports Server (NTRS)

    Byrd, Gregory T.; Nakano, Russell; Delagi, Bruce A.

    1987-01-01

    This paper describes a protocol to support point-to-point interprocessor communications with multicast. Dynamic, cut-through routing with local flow control is used to provide a high-throughput, low-latency communications path between processors. In addition multicast transmissions are available, in which copies of a packet are sent to multiple destinations using common resources as much as possible. Special packet terminators and selective buffering are introduced to avoid a deadlock during multicasts. A simulated implementation of the protocol is also described.

  19. CUTTING AND WEDGING JACKET REMOVER

    DOEpatents

    Freedman, M.; Raynor, S.

    1959-04-01

    A tool is presented for stripping cladded jackets from fissionable fuel elements. The tool is a tube which fits closely around the jacket and which has two cutting edges at opposite sides of one end. These cutting edges are adjusted to penetrate only the jacket so that by moving the edges downward the jacket is cut into two pieces.

  20. Characteristics of a piezoresistive accelerometer in shock environments up to 150,000 G

    SciTech Connect

    Bateman, V.I.; Davie, N.T.; Brown, F.A.

    1995-03-01

    The characteristics of a piezoresistive accelerometer in shock environments are being studied at Sandia National Laboratories in the Mechanical Shock Testing Laboratory. A Hopkinson bar capability has been developed to extend our undemanding of the piezoresistive accelerometer, in two mechanical configurations, in the high frequency, high shock environments where measurements are being made. Two different Hopkinson bar materials are being used: Titanium and beryllium The in-axis performance of the piezoresistive accelerometer for frequencies of dc-10 kHz and shock magnitudes of up to 150,000 g as determined from measurements with a titanium Hopkinson bar are presented. The beryllium Hopkinson bar configuration is described. Preliminary in-axis characteristics of the piezoresistive accelerometer at a nominal shock level of 50,000 g for a frequency range of DC-30 kHz determined from the beryllium bar are presented.

  1. The use of a beryllium Hopkinson bar to characterize a piezoresistive accelerometer in shock environments

    SciTech Connect

    Bateman, V.I.; Brown, F.A.; Davie, N.T.

    1996-03-01

    The characteristics of a piezoresistive accelerometer in shock environments are being studied at Sandia National Laboratories in the Mechanical Shock Testing Laboratory. A Hopkinson bar capability has been developed to extend our understanding of the piezoresistive accelerometer, in two mechanical configurations, in the high frequency, high shock environments where measurements are being made. In this paper, the beryllium Hopkinson bar configuration with a laser doppler vibrometer as the reference measurement is described. The in-axis performance of the piezoresistive accelerometer for frequencies of dc-50 kHz and shock magnitudes of up to 70,000 g as determined from measurements with a beryllium Hopkinson bar are presented. Preliminary results of characterizations of the accelerometers subjected to cross-axis shocks in a split beryllium Hopkinson bar configuration are presented.

  2. Bulk Micromachined 6H-SiC High-g Piezoresistive Accelerometer Fabricated and Tested

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S.

    2002-01-01

    High-g accelerometers are needed in certain applications, such as in the study and analysis of high-g impact landings and projectiles. Also, these accelerometers must survive the high electromagnetic fields associated with the all-electric vehicle technology needed for aerospace applications. The choice of SiC is largely due to its excellent thermomechanical properties over conventional silicon-based accelerometers, whose material properties inhibit applicability in high electromagnetic radiation and high temperatures (>150 C) unless more complex and sometimes costly packaging schemes are adopted. This work was the outcome of a NASA Glenn Research Center summer internship program, in collaboration with Cornell University and the Munitions Directorate of the U.S. Air Force in Eglin, Florida. It aimed to provide the enabling technology infrastructure (modeling, fabrication, and validation) for the implementation of SiC accelerometers designed specifically for harsh environments.

  3. Validation of uniaxial and triaxial accelerometers for the assessment of physical activity in preschool children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Given the unique physical activity patterns of preschoolers, wearable electronic devices for quantitative assessment of physical activity require validation in this population. Study objective was to validate uniaxial and triaxial accelerometers in preschoolers. Room calorimetry was performed over 3...

  4. Quantified reflex strategy using an iPod as a wireless accelerometer application.

    PubMed

    LeMoyne, Robert; Mastroianni, Timothy; Grundfest, Warren

    2012-01-01

    A primary aspect of a neurological evaluation is the deep tendon reflex, frequently observed through the patellar tendon reflex. The reflex response provides preliminary insight as to the status of the nervous system. A quantified reflex strategy has been developed, tested, and evaluated though the use of an iPod as a wireless accelerometer application integrated with a potential energy device to evoke the patellar tendon reflex. The iPod functions as a wireless accelerometer equipped with robust software, data storage, and the capacity to transmit the recorded accelerometer waveform of the reflex response wirelessly through email for post-processing. The primary feature of the reflex response acceleration waveform is the maximum acceleration achieved subsequent to evoking the patellar tendon reflex. The quantified reflex strategy using an iPod as a wireless accelerometer application yields accurate and consistent quantification of the reflex response.

  5. Comparison of linear and non-linear models for predicting energy expenditure from raw accelerometer data.

    PubMed

    Montoye, Alexander H K; Begum, Munni; Henning, Zachary; Pfeiffer, Karin A

    2017-02-01

    This study had three purposes, all related to evaluating energy expenditure (EE) prediction accuracy from body-worn accelerometers: (1) compare linear regression to linear mixed models, (2) compare linear models to artificial neural network models, and (3) compare accuracy of accelerometers placed on the hip, thigh, and wrists. Forty individuals performed 13 activities in a 90 min semi-structured, laboratory-based protocol. Participants wore accelerometers on the right hip, right thigh, and both wrists and a portable metabolic analyzer (EE criterion). Four EE prediction models were developed for each accelerometer: linear regression, linear mixed, and two ANN models. EE prediction accuracy was assessed using correlations, root mean square error (RMSE), and bias and was compared across models and accelerometers using repeated-measures analysis of variance. For all accelerometer placements, there were no significant differences for correlations or RMSE between linear regression and linear mixed models (correlations: r  =  0.71-0.88, RMSE: 1.11-1.61 METs; p  >  0.05). For the thigh-worn accelerometer, there were no differences in correlations or RMSE between linear and ANN models (ANN-correlations: r  =  0.89, RMSE: 1.07-1.08 METs. Linear models-correlations: r  =  0.88, RMSE: 1.10-1.11 METs; p  >  0.05). Conversely, one ANN had higher correlations and lower RMSE than both linear models for the hip (ANN-correlation: r  =  0.88, RMSE: 1.12 METs. Linear models-correlations: r  =  0.86, RMSE: 1.18-1.19 METs; p  <  0.05), and both ANNs had higher correlations and lower RMSE than both linear models for the wrist-worn accelerometers (ANN-correlations: r  =  0.82-0.84, RMSE: 1.26-1.32 METs. Linear models-correlations: r  =  0.71-0.73, RMSE: 1.55-1.61 METs; p  <  0.01). For studies using wrist-worn accelerometers, machine learning models offer a significant improvement in EE prediction

  6. Sensing and Control Electronics for Low-Mass Low-Capacitance MEMS Accelerometers

    DTIC Science & Technology

    2002-05-01

    applications generally require sub µg/rtHz noise floor and less than 0.1% overall scale factor error in acceleration measurement. Micro accelerometers...Figure 1-2 shows a generic block diagram of the system under study. The first goal of this research is to design a low noise capacitive sensing...µg/ Transducer Sensing Circuit Control System Acceleration Digital Output Figure 1-2: Generic block diagram of accelerometer system studied in this

  7. Gyro and Accelerometer Based Navigation System for a Mobile Autonomous Robot.

    DTIC Science & Technology

    1985-12-02

    8217[ C) ~OF ~ FEB 13 1986 J GYRO AND ACCELEROMETER BASED NAVIGATION SYSTEM FOR A MOBILE AUTONOMOUS ROBOT Roland J. Bloom William J. Ramey, Jr. Captain...ACCELEROMETER BASED NAVIGATION SYSTEM FOR A MOBILE AUTONOMOUS ROBOT THESIS Roland J. Bloom William J. Ramey, Jr. Captain, USAF Captain, USAF AF IT/GA/GE/ENG/85D...MOBILE AUTONOMOUS ROBOT THE SI S Presented to the Faculty of the School of Engineering of the Air Force Institute of Technology Air University In

  8. Application of the Satellite Triaxial Accelerometer Experiment to Atmospheric Density and Wind Studies.

    DTIC Science & Technology

    1982-03-04

    EVERETT R. SWIFT U DTIC " 4 MARCH 1982 -J_ OCT 2 9 1 3 Approed for publis rebo.; dlributon unlimited. AERONOMY DIVISION PROJECT 6690 , AIR FORCE...Accelerometers Thermospheric density; . * Aerodynic drag Atmospheric density -- A new satellite triaxial accelerometer system has been developed. This...understanding of dynamic processes in the atmosphere and for the improvement of atmospheric models. i’ :. 4 Unclassified SECURITY CLASSIFICATION OF THIS

  9. 49 CFR 234.237 - Reverse switch cut-out circuit.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Reverse switch cut-out circuit. 234.237 Section....237 Reverse switch cut-out circuit. A switch, when equipped with a switch circuit controller connected... warning system can only be cut out when the switch point is within one-half inch of full reverse position....

  10. 49 CFR 234.237 - Reverse switch cut-out circuit.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Reverse switch cut-out circuit. 234.237 Section....237 Reverse switch cut-out circuit. A switch, when equipped with a switch circuit controller connected... warning system can only be cut out when the switch point is within one-half inch of full reverse position....

  11. 49 CFR 234.237 - Reverse switch cut-out circuit.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Reverse switch cut-out circuit. 234.237 Section....237 Reverse switch cut-out circuit. A switch, when equipped with a switch circuit controller connected... warning system can only be cut out when the switch point is within one-half inch of full reverse position....

  12. Modelling of the MEA float zone using accelerometer data

    NASA Technical Reports Server (NTRS)

    Alexander, J. Iwan D.

    1993-01-01

    During a floating zone experiment involving the growth of indium on a recent orbiter mission, (STS 32) oscillation of the zone shapes were observed to occur in response to the background acceleration. An understanding of the nature of the response of the zone shape to forced (g-jitter) oscillations and predictions of its impact on future experiments is of great interest not only to the PI's but to other commercial and academic investigators who plan to fly similar experiments in the orbiter and on space station. Motivated by this, a 15 month study was undertaken to analyze the nature of the g-sensitivity of the STS 32 floating zone crystal growth experiment. Numerical models were used to describe the time-dependent free surface motion of the zone as it responds to the spacecraft residual acceleration. Relevant experimental data concerning the acceleration environment was obtained from the Honeywell in Space Accelerometer (HISA) investigators through MSFC's ACAP program and processed and analyzed. For the indium floating zone experiment, a series of calculations were made using time-dependent axial accelerations g(t). The form of g(t) included simple sinusoidal disturbances as well as actual data (subject to appropriate filtering) measured on the STS 32 mission. Focus was on the calculation of the response of the free surface of the zone as well as the internal flows and internal heat transfer. The influence of solidification on the response of the zone shape was also examined but found to be negligible.

  13. Ambulatory respiratory rate detection using ECG and a triaxial accelerometer.

    PubMed

    Chan, Alexander M; Ferdosi, Nima; Narasimhan, Ravi

    2013-01-01

    Continuous monitoring of respiratory rate in ambulatory conditions has widespread applications for screening of respiratory diseases and remote patient monitoring. Unfortunately, minimally obtrusive techniques often suffer from low accuracy. In this paper, we describe an algorithm with low computational complexity for combining multiple respiratory measurements to estimate breathing rate from an unobtrusive chest patch sensor. Respiratory rates derived from the respiratory sinus arrhythmia (RSA) and modulation of the QRS amplitude of electrocardiography (ECG) are combined with a respiratory rate derived from tri-axial accelerometer data. The three respiration rates are combined by a weighted average using weights based on quality metrics for each signal. The algorithm was evaluated on 15 elderly subjects who performed spontaneous and metronome breathing as well as a variety of activities of daily living (ADLs). When compared to a reference device, the mean absolute error was 1.02 breaths per minute (BrPM) during metronome breathing, 1.67 BrPM during spontaneous breathing, and 2.03 BrPM during ADLs.

  14. Can accelerometers detect mass variations in Amazonian trees?

    NASA Astrophysics Data System (ADS)

    van Emmerik, Tim; Steele-Dunne, Susan; Gentine, Pierre; Guerin, Marceau; Hut, Rolf; Oliveira, Rafael; van de Giesen, Nick

    2016-04-01

    The mass of trees is influenced by physiological processes within the tree (e.g. transpiration and root water uptake), as well as external loads (e.g. intercepted precipitation). Recent studies have found diurnal variations in radar backscatter over vegetated areas, which might be attributed to mass changes of the vegetation layer. Field measurements are required to study the driving processes. This study aims to use measured three-dimensional displacement and acceleration of trees, to detect and quantify their diurnal (bio)mass variations. Accelerometers and dendrometers were installed on seven different tree species in the Amazon rainforest. Trees were selected to cover a broad range of wood density. Using spectral analysis, the governing frequencies in the acceleration time series were found. The governing frequencies showed a diurnal pattern, as well as a change during precipitation events. Our results suggest that we can separate and potentially quantify tree mass changes due to (1) internal water redistribution and (2) intercepted precipitation. This will allow further investigation of the effect of precipitation and water stress on tree dynamics in forest canopies.

  15. Modeling perceived stress via HRV and accelerometer sensor streams.

    PubMed

    Wu, Min; Cao, Hong; Nguyen, Hai-Long; Surmacz, Karl; Hargrove, Caroline

    2015-08-01

    Discovering and modeling of stress patterns of human beings is a key step towards achieving automatic stress monitoring, stress management and healthy lifestyle. As various wearable sensors become popular, it becomes possible for individuals to acquire their own relevant sensory data and to automatically assess their stress level on the go. Previous studies for stress analysis were conducted in the controlled laboratory and clinic settings. These studies are not suitable for stress monitoring in one's daily life as various physical activities may affect the physiological signals. In this paper, we address such issue by integrating two modalities of sensors, i.e., HRV sensors and accelerometers, to monitor the perceived stress levels in daily life. We gathered both the heart and the motion data from 8 participants continuously for about 2 weeks. We then extracted features from both sensory data and compared the existing machine learning methods for learning personalized models to interpret the perceived stress levels. Experimental results showed that Bagging classifier with feature selection is able to achieve a prediction accuracy 85.7%, indicating our stress monitoring on daily basis is fairly practical.

  16. Optical fiber accelerometer based on MEMS torsional micromirror

    NASA Astrophysics Data System (ADS)

    Zeng, Fanlin; Zhong, Shaolong; Xu, Jing; Wu, Yaming

    2008-03-01

    A novel structure of optical fiber accelerometer based on MEMS torsional micro-mirror is introduced, including MEMS torsional micro-mirror and optical signal detection. The micro-mirror is a non-symmetric one, which means that the torsional bar supporting the micro-mirror is not located in the axis where the center of the micro-mirror locates. The optical signal detection is composed of PIN diode and dual fiber collimator, which is very sensitive to the coupling angle between the input fiber and output fiber. The detection principle is that acceleration is first transformed into torsional angle of the micro-mirror, then, optical insertion loss of the dual fiber collimator caused by the angle can be received by PIN. So under the flow of acceleration to torsional angle to optical signal attenuation to optical power detection, the acceleration is detected. The theory about sensing and optical signal detect of the device are discussed in this paper. The sensitive structure parameters and performance parameters are calculated by MATLAB. To simulate the static and modal analysis, the finite element analysis, ANSYS, is employed. Based on the above calculation, several optimization methods and the final structure parameters are given. The micro-mirror is completed by using silicon-glass bonding and deep reactive ion etching (DRIE). In the experiment, the acceleration is simulated by electrostatic force and the test results show that the static acceleration detection agrees with the theory analysis very well.

  17. BepiColombo ISA accelerometer: ready for launch

    NASA Astrophysics Data System (ADS)

    Francesco, Santoli; Valerio, Iafolla; Emiliano, Fiorenza; Carlo, Lefevre; Lucchesi David, M.; Marco, Lucente; Carmelo, Magnafico; Sergio, Nozzoli; Roberto, Peron

    2016-04-01

    To be launched in 2017, ESA mission BepiColombo will perform a thorough study of the planet Mercury and its environment. Among the wide range of its scientific objectives, an important set is constituted by the so-called Radio Science Experiments (RSE), which will study the gravitational field and rotation of the planet, and will perform very precise tests of general relativity theory. The fulfilment of these scientific objectives will be made possible by a precise orbit determination of the Mercury Planetary Orbiter (MPO), at the same time estimating a number of relevant parameters. In order to reach the required level of accuracy in recovering these parameters, the data coming from the high-sensitivity ISA (Italian Spring Accelerometer) instrument onboard the MPO probe will be used: the first time for a deep-space probe. After a long path of design and development, the instrument is now ready for integration into MPO. Following a brief description of the RSE in the context of the mission, the instrument and its capabilities will be reviewed. Emphasis will be given to the foreseen strategies for its operation in the various phases of the mission, along with the manifold calibration possibilities.

  18. Cutting Plane Algorithms for Maximum Problems

    DTIC Science & Technology

    1991-12-01

    Bazaraa and Shetty (1979). For variational inequalities, references on the cutting plane approach are considerably less. Zuhovickii et al. (1969) (see...and can be expressed as a convex combination of a finite number of extreme points [see, e.g., Bazaraa et al., (1990)], For VI problems, both U and X are...unique solution (see, page 234 of Bazaraa and Shetty, 1979)., 32 Figure 4: A ’Strong’ Solution to a Variational Inequality Problem The rate of

  19. Valid detection of self-propelled wheelchair driving with two accelerometers.

    PubMed

    Kooijmans, H; Horemans, H L D; Stam, H J; Bussmann, J B J

    2014-11-01

    This study assessed whether self-propelled wheelchair driving can be validly detected by a new method using a set of two commonly used accelerometers.In a rehabilitation centre, 10 wheelchair-bound persons with spinal cord injury (SCI) (aged 29-63 years) performed a series of representative daily activities according to a protocol including self-propelled wheelchair driving and other activities. Two ActiGraph GT3X+ accelerometers were used; one was attached at the wrist, the other to the spokes of the wheelchair wheel. Based on the movement intensity of the two accelerometers, a custom-made algorithm in MatLab differentiated between self-propelled wheelchair driving and other activities (e.g. being pushed or arm movements not related to wheelchair driving). Video recordings were used for reference. Validity scores between the accelerometer output and the video analyses were expressed in terms of agreement, sensitivity and specificity scores.Overall agreement for the detection of self-propelled wheelchair driving was 85%; sensitivity was 88% and specificity 83%. Disagreement between accelerometer output and video analysis was largest for wheelchair driving at very low speed on a treadmill, wheelchair driving on a slope on a treadmill, and being pushed in the wheelchair whilst making excessive arm movements.Valid detection of self-propelled wheelchair driving is provided by two accelerometers and a simple algorithm. Disagreement with the video analysis was largest during three atypical daily activities.

  20. Validity of gait asymmetry estimation by using an accelerometer in individuals with hemiparetic stroke

    PubMed Central

    Oyake, Kazuaki; Yamaguchi, Tomofumi; Sugasawa, Masafumi; Oda, Chihiro; Tanabe, Shigeo; Kondo, Kunitsugu; Otaka, Yohei; Momose, Kimito

    2017-01-01

    [Purpose] The purpose of this study was to evaluate the validity of estimating step time and length asymmetries, using an accelerometer against force plate measurements in individuals with hemiparetic stroke. [Subjects and Methods] Twenty-four individuals who previously had experienced a stroke were asked to walk without using a cane or manual assistance on a 16-m walkway. Step time and length were measured using force plates, which is the gold standard for assessing gait asymmetry. In addition to ground reaction forces, trunk acceleration was simultaneously measured using an accelerometer. To estimate step time asymmetry using accelerometer data, the time intervals between forward acceleration peaks for each leg were calculated. To estimate step length asymmetry using accelerometer data, the integration of the positive vertical accelerations following initial contact of each leg was calculated. Asymmetry was considered the affected side value divided by the unaffected side value. [Results] Significant correlations were found between the accelerometer and the force plates for step time and length asymmetries (rho=0.83 and rho=0.64, respectively). [Conclusion] An accelerometer might be useful for assessing step time and length asymmetries in individuals with hemiparetic stroke, although improvements are needed for estimating the accuracy of step length asymmetry. PMID:28265163

  1. Estimating daily walking distance of captive African elephants using an accelerometer.

    PubMed

    Rothwell, Emily S; Bercovitch, Fred B; Andrews, Jeff R M; Anderson, Matthew J

    2011-01-01

    Two central concerns for elephant husbandry and management are whether zoological enclosures are appropriately sized and the degree to which naturalistic exercise and activity are observed in such enclosures. In order to address these issues, accurate data on the daily walking distance of elephants both in situ and ex situ are necessary. We used an accelerometer, a pedometer that measures step count and activity level, to estimate walking distance in African elephants (Loxodonta africana) at the San Diego Zoo's Wild Animal Park. The accelerometer was worn simultaneously with a GPS unit that recorded actual walking distance. Estimates of walking distance were extrapolated from the accelerometer and compared with actual distances determined by GPS data. The accelerometer was found to overestimate step count, and subsequently walking distance, by including false counts of steps. Extrapolating walking distance based upon stride length measurements did not match actual GPS walking distance. However, activity level output from the accelerometer significantly correlated with actual GPS walking distance. In addition, we report that the rate of movement is comparable to that reported in other zoological settings. We provide a linear regression equation that can be utilized by other institutions to estimate daily walking distance of elephants in their collection who are outfitted with accelerometers.

  2. Physical activity using wrist-worn accelerometers: comparison of dominant and non-dominant wrist.

    PubMed

    Dieu, Olivier; Mikulovic, Jacques; Fardy, Paul S; Bui-Xuan, Gilles; Béghin, Laurent; Vanhelst, Jérémy

    2016-01-07

    The purpose of this study was to determine whether there is a difference in physical activity assessment between a wrist-worn accelerometer at the dominant or non-dominant arm. The secondary purpose was to assess the concurrent validity of measures of physical activity from the wrist-worn accelerometer and the waist-worn accelerometer. Forty adults wore three accelerometers simultaneously, one on the waist and one each on the non-dominant wrist and dominant wrist, respectively, for 24 consecutive hours of free-living conditions. Data were uploaded from the monitor to a computer following a 1-day test period. There were no significant differences in physical activity when comparing the dominant versus the non-dominant wrist, regardless of axis (P>0·05). Mean daily accelerometer output data from both wrists were strongly correlated with average counts per minute from the ActiGraph worn around the waist (r = 0·88, P<0·001). Findings suggest that the choice to wear the accelerometer on the non-dominant or dominant wrist has no impact on results. Data from this study contribute to the knowledge of how to best assess physical activity habits.

  3. Validity of gait asymmetry estimation by using an accelerometer in individuals with hemiparetic stroke.

    PubMed

    Oyake, Kazuaki; Yamaguchi, Tomofumi; Sugasawa, Masafumi; Oda, Chihiro; Tanabe, Shigeo; Kondo, Kunitsugu; Otaka, Yohei; Momose, Kimito

    2017-02-01

    [Purpose] The purpose of this study was to evaluate the validity of estimating step time and length asymmetries, using an accelerometer against force plate measurements in individuals with hemiparetic stroke. [Subjects and Methods] Twenty-four individuals who previously had experienced a stroke were asked to walk without using a cane or manual assistance on a 16-m walkway. Step time and length were measured using force plates, which is the gold standard for assessing gait asymmetry. In addition to ground reaction forces, trunk acceleration was simultaneously measured using an accelerometer. To estimate step time asymmetry using accelerometer data, the time intervals between forward acceleration peaks for each leg were calculated. To estimate step length asymmetry using accelerometer data, the integration of the positive vertical accelerations following initial contact of each leg was calculated. Asymmetry was considered the affected side value divided by the unaffected side value. [Results] Significant correlations were found between the accelerometer and the force plates for step time and length asymmetries (rho=0.83 and rho=0.64, respectively). [Conclusion] An accelerometer might be useful for assessing step time and length asymmetries in individuals with hemiparetic stroke, although improvements are needed for estimating the accuracy of step length asymmetry.

  4. Free Fall tests for the qualification of Ultra sensitive accelerometers for space missions

    NASA Astrophysics Data System (ADS)

    Françoise, Liorzou; Pierre, Marque Jean; Santos Rodrigues, Manuel

    ONERA is developing since a long time accelerometers for space applications in the field of Earth Observations and Fundamental Physics. The more recent examples are the accelerom-eters embarked on the ESA GOCE mission launched in March 2009, dedicated to the Earth precise gravity field mapping, and the accelerometers of the CNES MICROSCOPE mission dedicated to the in orbit test of the Equivalence Principle. Those Ultra sensitive accelerome-ters are optimised for the space environment and operate over an acceleration range less than 10-6 ms-2 with an outstanding accuracy around 10-12 ms-2Hz1/2. Their testability on ground requires creating a low gravity environment in order to verify their functionalities and partially their performances before their delivery before launch. Free fall tests are the only way to ob-tain such a microgravity environment in representating space conditions. The presentation will show in a first part the results of the free fall test campaigns performed in the 120-meter high ZARM drop tower that have led to the qualification of the GOCE accelerometers. In a second part, it will describe the test plan being conducted to assess the best free-fall environment for the MICROSCOPE accelerometers. In particular, some efforts have been paid by ZARM and ONERA to develop a dedicated "free-flyer"capsule, in order to reduce the residual drag acceleration along the fall. Some results from the preliminary tests performed in preparation to the MICROSCOPE qualification campaign will be also presented.

  5. Early recognition of regional cardiac ischemia using a 3-axis accelerometer sensor.

    PubMed

    Elle, Ole Jakob; Halvorsen, Steinar; Gulbrandsen, Martin Gunnar; Aurdal, Lars; Bakken, Andre; Samset, Eigil; Dugstad, Harald; Fosse, Erik

    2005-08-01

    Perioperative mortality in coronary artery bypass grafting is usually caused by reduced left ventricular function due to regional myocardial ischemia or infarction. Post-operative graft occlusion is a well-known problem in coronary surgery. A sensitive tool to detect graft occlusion and monitor myocardial function may give the opportunity to revise malfunctioning grafts before departure from the hospital. This paper describes how a new method can detect cardiac ischemia using a 3-axis piezoelectric accelerometer. In three anesthetized pigs, a 3-axis piezoelectric accelerometer was sutured on the lateral free wall of the left ventricle. The left anterior descending (LAD) was occluded for different time periods and the accelerometer data were sampled with a PC. Short-time Fourier transform was calculated based on the accelerometer time series. The results were visualized using a 2D color-coded time-frequency plot. In the area of occlusion, a change to stronger power of higher harmonics was observed. Consequently, a difference value between the instant frequency pattern and a reference frequency pattern showed a rise in absolute value during the occlusion period. The preliminary results indicate that early recognition of regional cardiac ischemia is possible by analyzing accelerometer data acquired from the three animal trials using the prototype 3-axis accelerometer sensor.

  6. Use of a Wireless Network of Accelerometers for Improved Measurement of Human Energy Expenditure.

    PubMed

    Montoye, Alexander H; Dong, Bo; Biswas, Subir; Pfeiffer, Karin A

    2014-01-01

    Single, hip-mounted accelerometers can provide accurate measurements of energy expenditure (EE) in some settings, but are unable to accurately estimate the energy cost of many non-ambulatory activities. A multi-sensor network may be able to overcome the limitations of a single accelerometer. Thus, the purpose of our study was to compare the abilities of a wireless network of accelerometers and a hip-mounted accelerometer for the prediction of EE. Thirty adult participants engaged in 14 different sedentary, ambulatory, lifestyle and exercise activities for five minutes each while wearing a portable metabolic analyzer, a hip-mounted accelerometer (AG) and a wireless network of three accelerometers (WN) worn on the right wrist, thigh and ankle. Artificial neural networks (ANNs) were created separately for the AG and WN for the EE prediction. Pearson correlations (r) and the root mean square error (RMSE) were calculated to compare criterion-measured EE to predicted EE from the ANNs. Overall, correlations were higher (r = 0.95 vs. r = 0.88, p < 0.0001) and RMSE was lower (1.34 vs. 1.97 metabolic equivalents (METs), p < 0.0001) for the WN than the AG. In conclusion, the WN outperformed the AG for measuring EE, providing evidence that the WN can provide highly accurate estimates of EE in adults participating in a wide range of activities.

  7. Improved mapping of planetary gravitational field with an electrostatic accelerometer/gradiometer

    NASA Astrophysics Data System (ADS)

    Foulon, Bernard; Huynh, Phuong-Anh; Liorzou, Francoise; Christophe, Bruno; Hardy, Emilie; Boulanger, Damien; Lebat, Vincent; Perrot, Eddy

    2015-04-01

    ONERA has a proven record spanning several years in developing the most accurate accelerometers for geodesy missions. They are still operational in the GRACE mission and their successors for the GRACE-FO mission will fly in 2017. Finally, the GOCE mission has shown the benefit of using a gradiometer for the direct measurement of the gravity field. Now, ONERA proposes a new accelerometer design, MicroSTAR, for interplanetary missions. This design based on the same technology as for the GRACE and GOCE space missions, with the notable addition of a bias rejection system, has a reduced mass and consumption. The accelerometer is embarked on Uranus Pathfinder (mission proposal for Cosmic M4) as up-scope instrument to achieve two scientific objectives: 1) to determine the gravity fields of Uranus and the satellites, allowing for a better understanding of the planet interior composition, 2) to test gravity at the largest possible length scales to search for deviations from General Relativity. The success of using accelerometer for geodesy mission could be imported in the planetary science field. The poster details the accuracy which can be achieved on the gravity potential field according to different accelerometer configurations. It describes the instrument and its integration inside an interplanetary probe. Finally, it explains the benefit of using this electrostatic accelerometer complementary to radio science technology for improved planetary gravitational field measurements.

  8. Improvement of the Planetary Gravitational Potentiel Field Knwoledge with Accurate Electrostatic Accelerometer / Gradiometer

    NASA Astrophysics Data System (ADS)

    Christophe, B.; Lebat, V.; Foulon, B.; Liorzou, F.; Perrot, E.; Boulanger, D.; Hardy, E.

    2014-12-01

    ONERA has developed since several years the most accurate accelerometers for the geodesy mission. The accelerometers are still operational in the GRACE mission. Their successors for the GRACE-FO mission are under manufacturing and will fly in 2017. Finally, the GOCE mission has proved the interest of gradiometer for a direct measurement of the gravity field.Now, ONERA proposes a new design of accelerometer, MicroSTAR, for interplanetary mission. It inherits of the same technology but with reduced mass and consumption. It has been proposed in several missions towards outer planets in order to test the deviation to the relativity general over large distance to the sun (with the addition of a bias rejection system). But the same instrument could be interesting to improve our knowledge of the planetary gravitational potential field, allowing a better understanding of the planet interior composition. The success of using accelerometer for geodesy mission could be imported in the planetary science.The paper will present the accuracy achievable on the gravity potential field according to different accelerometer configurations (one accelerometer, one gradiometer arm or a complete 3-axis gradiometer). Then, the instrument will be described and the integration of the instrument inside an interplanetary probe will be evoked.

  9. Linearity enhancement of scale factor in an optical interrogated micromechanical accelerometer.

    PubMed

    Zhang, Yu; Feng, Lishuang; Wang, Xiao; Wang, Yang

    2016-08-01

    A method to reduce the residual stress of support arms in an optical interrogated micromechanical accelerometer is proposed in order to enhance the linearity of the scale factor of the accelerometer. First, the behavior of residual stress in support arms is analyzed in detail, and the simulation of shape curvature caused by residual stress in aluminum-made support arms is completed using finite element analysis. Then, by comparing two different materials of support arms (aluminum-made and silicon-made support arms), a modified fabrication is introduced in order to reduce the unexpected residual stress in support arms. Finally, based on contrast experiments, the linearity of the scale factor of accelerometers with aluminum-made and silicon-made support arms is measured using the force feedback test system, respectively. Results show that the linearity of the scale factor of the accelerometer with silicon-made support arms is 0.85%, which is reduced about an order of magnitude compared to that of the accelerometer with aluminum-made support arms with the linearity of scale factor of 7.48%; linearity enhancement of the scale factor is validated. This allows accuracy improvement of the optical interrogated micromechanical accelerometer in the application of inertial navigation and positioning.

  10. Use of a Wireless Network of Accelerometers for Improved Measurement of Human Energy Expenditure

    PubMed Central

    Montoye, Alexander H.; Dong, Bo; Biswas, Subir; Pfeiffer, Karin A.

    2014-01-01

    Single, hip-mounted accelerometers can provide accurate measurements of energy expenditure (EE) in some settings, but are unable to accurately estimate the energy cost of many non-ambulatory activities. A multi-sensor network may be able to overcome the limitations of a single accelerometer. Thus, the purpose of our study was to compare the abilities of a wireless network of accelerometers and a hip-mounted accelerometer for the prediction of EE. Thirty adult participants engaged in 14 different sedentary, ambulatory, lifestyle and exercise activities for five minutes each while wearing a portable metabolic analyzer, a hip-mounted accelerometer (AG) and a wireless network of three accelerometers (WN) worn on the right wrist, thigh and ankle. Artificial neural networks (ANNs) were created separately for the AG and WN for the EE prediction. Pearson correlations (r) and the root mean square error (RMSE) were calculated to compare criterion-measured EE to predicted EE from the ANNs. Overall, correlations were higher (r = 0.95 vs. r = 0.88, p < 0.0001) and RMSE was lower (1.34 vs. 1.97 metabolic equivalents (METs), p < 0.0001) for the WN than the AG. In conclusion, the WN outperformed the AG for measuring EE, providing evidence that the WN can provide highly accurate estimates of EE in adults participating in a wide range of activities. PMID:25530874

  11. Cross-Cutting Faults

    NASA Technical Reports Server (NTRS)

    2005-01-01

    16 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows cross-cutting fault scarps among graben features in northern Tempe Terra. Graben form in regions where the crust of the planet has been extended; such features are common in the regions surrounding the vast 'Tharsis Bulge' on Mars.

    Location near: 43.7oN, 90.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Summer

  12. Photochemical cutting of fabrics

    DOEpatents

    Piltch, Martin S.

    1994-01-01

    Apparatus for the cutting of garment patterns from one or more layers of fabric. A laser capable of producing laser light at an ultraviolet wavelength is utilized to shine light through a pattern, such as a holographic phase filter, and through a lens onto the one or more layers of fabric. The ultraviolet laser light causes rapid photochemical decomposition of the one or more layers of fabric, but only along the pattern. The balance of the fabric of the one or more layers of fabric is undamaged.

  13. Drilling cost-cutting

    SciTech Connect

    Capuano, L.E. Jr.

    1996-12-31

    This presentation by Louis E. Capuano, Jr., President, ThermaSource, Inc., discusses cost-cutting in the drilling phase of geothermal energy exploration and production. All aspects of a geothermal project including the drilling must be streamlined to make it viable and commercial. If production could be maximized from each well, there would be a reduction in drilling costs. This could be achieved in several ways, including big hole and multi-hole completion, directional drilling, better knowledge of the resource and where to penetrate, etc.

  14. 3D sensing for machine guidance in meat cutting applications

    NASA Astrophysics Data System (ADS)

    Daley, Wayne; Britton, Doug; Usher, Colin; Diao, Mamadou; Ruffin, Kevin

    2005-11-01

    Most cutting and deboning operations in meat processing require accurate cuts be made to obtain maximum yield and ensure food safety. This is a significant concern for purveyors of deboned product. This task is made more difficult by the variability that is present in most natural products. The specific application of interest in this paper is the production of deboned poultry breast. This is typically obtained from a cut of the broiler called a 'front half' that includes the breast and the wings. The deboning operation typically consists of a cut that starts at the shoulder joint and then continues along the scapula. Attentive humans with training do a very good job of making this cut. The breast meat is then removed by pulling on the wings. Inaccurate cuts lead to poor yield (amount of boneless meat obtained relative to the weight of the whole carcass) and increase the probability that bone fragments might end up in the product. As equipment designers seek to automate the deboning operation, the cutting task has been a significant obstacle to developing automation that maximizes yield without generating unacceptable levels of bone fragments. The current solution is to sort the bone-in product into different weight ranges and then to adjust the deboning machines to the average of these weight ranges. We propose an approach for obtaining key cut points by extrapolation from external reference points based on the anatomy of the bird. We show that this approach can be implemented using a stereo imaging system, and the accuracy in locating the cut points of interest is significantly improved. This should result in more accurate cuts and with this concomitantly improved yield while reducing the incidence of bones. We also believe the approach could be extended to the processing of other species.

  15. Effect of Moisture Content of Paper Material on Laser Cutting

    NASA Astrophysics Data System (ADS)

    Stepanov, Alexander; Saukkonen, Esa; Piili, Heidi; Salminen, Antti

    Laser technology has been used in industrial processes for several decades. The most advanced development and implementation took place in laser welding and cutting of metals in automotive and ship building industries. However, there is high potential to apply laser processing to other materials in various industrial fields. One of these potential fields could be paper industry to fulfill the demand for high quality, fast and reliable cutting technology. Difficulties in industrial application of laser cutting for paper industry are associated to lack of basic information, awareness of technology and its application possibilities. Nowadays possibilities of using laser cutting for paper materials are widened and high automation level of equipment has made this technology more interesting for manufacturing processes. Promising area of laser cutting application at paper making machines is longitudinal cutting of paper web (edge trimming). There are few locations at a paper making machine where edge trimming is usually done: wet press section, calender or rewinder. Paper web is characterized with different moisture content at different points of the paper making machine. The objective of this study was to investigate the effect of moisture content of paper material on laser cutting parameters. Effect of moisture content on cellulose fibers, laser absorption and energy needed for cutting is described as well. Laser cutting tests were carried out using CO2 laser.

  16. Cutting boards in Salmonella cross-contamination.

    PubMed

    Cliver, Dean O

    2006-01-01

    Cutting boards are commonly perceived as important fomites in cross-contamination of foods with agents such as Salmonella spp., despite the lack of supporting epidemiological data. A variety of woods and plastics have been used to make work surfaces for cutting. In general, wood is said to dull knives less than plastic, and plastic is seen as less porous than wood. Research to model the hypothetical cross-contamination has been done in a variety of ways and has yielded a variety of results. At least some of the work with knife-scarred plastic indicates that the surface is very difficult to clean and disinfect, although this may vary among the polymers used. High-density polyethylene, which is most used in commercial applications, has been shown to delaminate in response to knife scarring. Wood is intrinsically porous, which allows food juices and bacteria to enter the body of the wood unless a highly hydrophobic residue covers the surface. The moisture is drawn in by capillary action until there is no more free fluid on the surface, at which point immigration ceases. Bacteria in the wood pores are not killed instantly, but neither do they return to the surface. Destructive sampling reveals infectious bacteria for hours, but resurrection of these bacteria via knife edges has not been demonstrated. Small plastic cutting boards can be cleaned in a dishwasher (as can some specially treated wooden boards), but the dishwasher may distribute the bacteria onto other food-contact surfaces. Most small wooden boards (i.e., those with no metal joiners in them) can be sterilized in a microwave oven, but this should be unnecessary if accumulation of food residues is prevented. However, 2 epidemiological studies seem to show that cutting board cleaning habits have little influence on the incidence of sporadic salmonellosis. Further, one of these studies indicated that use of plastic cutting boards in home kitchens is hazardous, whereas use of wooden cutting boards is not.

  17. Approaches for predicting long-term sickness absence. Re: Schouten et al. "Screening manual and office workers for risk of long-term sickness absence: cut-off points for the Work Ability Index".

    PubMed

    van Amelsvoort, Ludovic Gpm; Jansen, Nicole W H; Kant, I Jmert

    2015-05-01

    who are in fact suffering from disease" (ie, situations of secondary prevention). This means that, when applying this definition on long-term sickness absence under the precondition that the individuals are still at work, screening enables the identification of high-risk individuals in the early "stages" of a "disease" that can progress into long-term sickness absence. In the case of the Schouten et al study, the population at risk, as derived from their predictive instrument, consists of workers with and without sickness absence, and as such excludes the use of the term "screening" in this case. To conclude, we have substantiated that, in addition to correct usage of the term "screening", careful selection of the study population, predictors and most importantly the aim of the predictive model are essential in the process of developing predictive instruments aimed at identifying workers at high risk of long-term sickness absence. Two fundamentally different approaches are possible. One approach aims at identifying workers on sick leave with either a below-average chance to return to work an/or a high risk for a successive episode of long-term sickness absence. From a methodological and practical point of view, such an instrument should be developed and validated among workers already on sick leave. A second approach aims at identifying workers who are still at work but at high risk for future long-term sickness absence. To develop and validate such an instrument, a study sample where workers already on sick leave are excluded is a prerequisite. Such instruments fit in a pro-active approach of preventing future sickness absence, where an early intervention can be offered to those workers with an increased risk for future sickness absence.

  18. Vibrator improves spark erosion cutting process

    NASA Technical Reports Server (NTRS)

    Thrall, L. R.

    1966-01-01

    Variable frequency mechanical vibrator improves spark erosion cutting process. The vibration of the cutting tip permits continual flushing away of residue around the cut area with nondestructive electric transformer oil during the cutting process.

  19. Development of a superconducting six-axis accelerometer. Final report, 1 April 1985-31 March 1988

    SciTech Connect

    Paik, H.J.; Parke, J.W.; Canavan, E.R.

    1989-07-01

    This report describes research on the superconducting six-axis accelerometer performed at the University of Maryland from April, 1985, to March,1988, under Air Force Contract F19628-85-K-0042. This report consists of four chapters. After an introduction and summary is given in Chapter 1, Chapter 2 discusses the theory of a superconducting six-axis accelerometer. The construction and test of the conducting six-axis accelerometer are given in Chapters 3 and 4, respectively. The superconducting six-axis accelerometer described in this report was invented to monitor the platform motions of a superconducting gravity gradiometer which is under development at the University of Maryland for space application. The signals from the accelerometer will be used to control the position and the attitude of the gradiometer platform. The superconducting six-axis accelerometer represents by itself a complete inertial navigation system. Integrated with the superconducting gravity gradiometer, it becomes a gradiometer-aided inertial navigation system.

  20. Validation of a novel smartphone accelerometer-based knee goniometer.

    PubMed

    Ockendon, Matthew; Gilbert, Robin E

    2012-09-01

    Loss of full knee extension following anterior cruciate ligament surgery has been shown to impair knee function. However, there can be significant difficulties in accurately and reproducibly measuring a fixed flexion of the knee. We studied the interobserver and the intraobserver reliabilities of a novel, smartphone accelerometer-based, knee goniometer and compared it with a long-armed conventional goniometer for the assessment of fixed flexion knee deformity. Five healthy male volunteers (age range 30 to 40 years) were studied. Measurements of knee flexion angle were made with a telescopic-armed goniometer (Lafayette Instrument, Lafayette, IN) and compared with measurements using the smartphone (iPhone 3GS, Apple Inc., Cupertino, CA) knee goniometer using a novel trigonometric technique based on tibial inclination. Bland-Altman analysis of validity and reliability including statistical analysis of correlation by Pearson's method was undertaken. The iPhone goniometer had an interobserver correlation (r) of 0.994 compared with 0.952 for the Lafayette. The intraobserver correlation was r = 0.982 for the iPhone (compared with 0.927). The datasets from the two instruments correlate closely (r = 0.947) are proportional and have mean difference of only -0.4 degrees (SD 3.86 degrees). The Lafayette goniometer had an intraobserver reliability +/- 9.6 degrees. The interobserver reliability was +/- 8.4 degrees. By comparison the iPhone had an interobserver reliability +/- 2.7 degrees and an intraobserver reliability +/- 4.6 degrees. We found the iPhone goniometer to be a reliable tool for the measurement of subtle knee flexion in the clinic setting.

  1. Cutting ice: nanowire regelation.

    PubMed

    Hynninen, Teemu; Heinonen, Vili; Dias, Cristiano L; Karttunen, Mikko; Foster, Adam S; Ala-Nissila, Tapio

    2010-08-20

    Even below its normal melting temperature, ice melts when subjected to high pressure and refreezes once the pressure is lifted. A classic demonstration of this regelation phenomenon is the passing of a thin wire through a block of ice when sufficient force is exerted. Here we present a molecular-dynamics study of a nanowire cutting through ice to unravel the molecular level mechanisms responsible for regelation. In particular, we show that the transition from a stationary to a moving wire due to increased driving force changes from symmetric and continuous to asymmetric and discontinuous as a hydrophilic wire is replaced by a hydrophobic one. This is explained at the molecular level in terms of the wetting properties of the wire.

  2. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Stefan Miska; Nicholas Takach; Kaveh Ashenayi

    2004-01-31

    Final design of the mast was completed (Task 5). The mast is consisting of two welded plate girders, set next to each other, and spaced 14-inches apart. Fabrication of the boom will be completed in two parts solely for ease of transportation. The end pivot connection will be made through a single 2-inch diameter x 4 feet-8 inch long 316 SS bar. During installation, hard piping make-ups using Chiksan joints will connect the annular section and 4-inch return line to allow full movement of the mast from horizontal to vertical. Additionally, flexible hoses and piping will be installed to isolate both towers from piping loads and allow recycling operations respectively. Calibration of the prototype Foam Generator Cell has been completed and experiments are now being conducted. We were able to generate up to 95% quality foam. Work is currently underway to attach the Thermo-Haake RS300 viscometer and install a view port with a microscope to measure foam bubble size and bubble size distribution. Foam rheology tests (Task 13) were carried out to evaluate the rheological properties of the proposed foam formulation. After successful completion of the first foam test, two sets of rheological tests were conducted at different foam flow rates while keeping other parameters constant (100 psig, 70F, 80% quality). The results from these tests are generally in agreement with the previous foam tests done previously during Task 9. However, an unanticipated observation during these tests was that in both cases, the frictional pressure drop in 2 inch pipe was lower than that in the 3 inch and 4 inch pipes. We also conducted the first foam cuttings transport test during this quarter. Experiments on aerated fluids without cuttings have been completed in ACTF (Task 10). Gas and liquid were injected at different flow rates. Two different sets of experiments were carried out, where the only difference was the temperature. Another set of tests was performed, which covered a wide range of

  3. Making the cut

    PubMed Central

    Millard, Chris

    2013-01-01

    ‘Deliberate self-harm’, ‘self-mutilation’ and ‘self-injury’ are just some of the terms used to describe one of the most prominent issues in British mental health policy in recent years. This article demonstrates that contemporary literature on ‘self-harm’ produces this phenomenon (to varying extents) around two key characteristics. First, this behaviour is predominantly performed by those identified as female. Second, this behaviour primarily involves cutting the skin. These constitutive characteristics are traced back to a corpus of literature produced in the 1960s and 1970s in North American psychiatric inpatient institutions; analysis shows how pre-1960 works were substantially different. Finally, these gendered and behavioural assertions are shown to be the result of historically specific processes of exclusion and emphasis. PMID:23741086

  4. Vortex cutting in superconductors

    NASA Astrophysics Data System (ADS)

    Glatz, A.; Vlasko-Vlasov, V. K.; Kwok, W. K.; Crabtree, G. W.

    2016-08-01

    Vortex cutting and reconnection is an intriguing and still-unsolved problem central to many areas of classical and quantum physics, including hydrodynamics, astrophysics, and superconductivity. Here, we describe a comprehensive investigation of the crossing of magnetic vortices in superconductors using time dependent Ginsburg-Landau modeling. Within a macroscopic volume, we simulate initial magnetization of an anisotropic high temperature superconductor followed by subsequent remagnetization with perpendicular magnetic fields, creating the crossing of the initial and newly generated vortices. The time resolved evolution of vortex lines as they approach each other, contort, locally conjoin, and detach, elucidates the fine details of the vortex-crossing scenario under practical situations with many interacting vortices in the presence of weak pinning. Our simulations also reveal left-handed helical vortex instabilities that accompany the remagnetization process and participate in the vortex crossing events.

  5. Cut By Troughs

    NASA Technical Reports Server (NTRS)

    2005-01-01

    1 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an impact crater cut by troughs which formed after the crater formed. The crater and troughs have large windblown ripples on their floors. The ripples, troughs, craters, and other surfaces in this scene have all been mantled by dust. Dark streaks on slopes indicate areas where avalanches of dry dust have occurred. These features are located on Sacra Mena, a large mesa in the Kasei Valles region.

    Location near: 25.4oN, 66.8oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  6. Self diagnostic accelerometer ground testing on a C-17 aircraft engine

    NASA Astrophysics Data System (ADS)

    Tokars, Roger P.; Lekki, John D.

    The self diagnostic accelerometer (SDA) developed by the NASA Glenn Research Center was tested for the first time in an aircraft engine environment as part of the Vehicle Integrated Propulsion Research (VIPR) program. The VIPR program includes testing multiple critical flight sensor technologies. One such sensor, the accelerometer, measures vibrations to detect faults in the engine. In order to rely upon the accelerometer, the health of the accelerometer must be ensured. Sensor system malfunction is a significant contributor to propulsion in flight shutdowns (IFSD) which can lead to aircraft accidents when the issue is compounded with an inappropriate crew response. The development of the SDA is important for both reducing the IFSD rate, and hence reducing the rate at which this component failure type can put an aircraft in jeopardy, and also as a critical enabling technology for future automated malfunction diagnostic systems. The SDA is a sensor system designed to actively determine the accelerometer structural health and attachment condition, in addition to making vibration measurements. The SDA uses a signal conditioning unit that sends an electrical chirp to the accelerometer and recognizes changes in the response due to changes in the accelerometer health and attachment condition. In an effort toward demonstrating the SDA's flight worthiness and robustness, multiple SDAs were mounted and tested on a C-17 aircraft engine. The engine test conditions varied from engine off, to idle, to maximum power. The two SDA attachment conditions used were fully tight and loose. The newly developed SDA health algorithm described herein uses cross correlation pattern recognition to discriminate a healthy from a faulty SDA. The VIPR test results demonstrate for the first time the robustness of the SDA in an engine environment characterized by high vibration levels.

  7. Combining global positioning system and accelerometer data to determine the locations of physical activity in children.

    PubMed

    Oreskovic, Nicolas M; Blossom, Jeff; Field, Alison E; Chiang, Sylvia R; Winickoff, Jonathan P; Kleinman, Ronald E

    2012-05-01

    National trends indicate that children and adolescents are not achieving sufficient levels of physical activity. Combining global positioning system (GPS) technology with accelerometers has the potential to provide an objective determination in locations where youth engage in physical activity. The aim of this study was to identify the optimal methods for collecting combined accelerometer and GPS data in youth, to best locate where children spend time and are physically active. A convenience sample of 24 mid-school children in Massachusetts was included. Accelerometers and GPS units were used to quantify and locate childhood physical activity over 5 weekdays and 2 weekend days. Accelerometer and GPS data were joined by time and mapped with a geographical information system (GIS) using ArcGIS software. Data were collected in winter, spring, summer in 2009-2010, collecting a total of 26,406 matched datapoints overall. Matched data yield was low (19.1% total), regardless of season (winter, 12.8%; spring, 30.1%; summer, 14.3%). Teacher-provided, pre-charged equipment yielded the most matched (30.1%; range: 10.1-52.3%) and greatest average days (6.1 days) of data. Across all seasons, children spent most of their time at home. Outdoor use patterns appeared to vary by season, with street use increasing in spring, and park and playground use increasing in summer. Children spent equal amounts of physical activity time at home and walking in the streets. Overall, the various methods for combining GPS and accelerometer data provided similarly low amounts of combined data. No combined GPS and accelerometer data collection method proved superior in every data return category, but use of GIS to map joined accelerometer and GPS data can demarcate childhood physical activity locations.

  8. Self Diagnostic Accelerometer Ground Testing on a C-17 Aircraft Engine

    NASA Technical Reports Server (NTRS)

    Tokars, Roger P.; Lekki, John D.

    2013-01-01

    The self diagnostic accelerometer (SDA) developed by the NASA Glenn Research Center was tested for the first time in an aircraft engine environment as part of the Vehicle Integrated Propulsion Research (VIPR) program. The VIPR program includes testing multiple critical flight sensor technologies. One such sensor, the accelerometer, measures vibrations to detect faults in the engine. In order to rely upon the accelerometer, the health of the accelerometer must be ensured. Sensor system malfunction is a significant contributor to propulsion in flight shutdowns (IFSD) which can lead to aircraft accidents when the issue is compounded with an inappropriate crew response. The development of the SDA is important for both reducing the IFSD rate, and hence reducing the rate at which this component failure type can put an aircraft in jeopardy, and also as a critical enabling technology for future automated malfunction diagnostic systems. The SDA is a sensor system designed to actively determine the accelerometer structural health and attachment condition, in addition to making vibration measurements. The SDA uses a signal conditioning unit that sends an electrical chirp to the accelerometer and recognizes changes in the response due to changes in the accelerometer health and attachment condition. In an effort toward demonstrating the SDAs flight worthiness and robustness, multiple SDAs were mounted and tested on a C-17 aircraft engine. The engine test conditions varied from engine off, to idle, to maximum power. The two SDA attachment conditions used were fully tight and loose. The newly developed SDA health algorithm described herein uses cross correlation pattern recognition to discriminate a healthy from a faulty SDA. The VIPR test results demonstrate for the first time the robustness of the SDA in an engine environment characterized by high vibration levels.

  9. Evaluation of Thermo-Mechanical Stability of COTS Dual-Axis MEMS Accelerometers for Space Applications

    NASA Technical Reports Server (NTRS)

    Sharma, Ashok K.; Teverovksy, Alexander; Day, John H. (Technical Monitor)

    2000-01-01

    Microelectromechanical systems in MEMS is one of the fastest growing technologies in microelectronics, and is of great interest for military and aerospace applications. Accelerometers are the earliest and most developed representatives of MEMS. First demonstrated in 1979, micromachined accelerometers were used in automobile industry for air bag crash- sensing applications since 1990. In 1999, N4EMS accelerometers were used in NASA-JPL Mars Microprobe. The most developed accelerometers for airbag crash- sensing are rated for a full range of +/- 50 G. The range of sensitivity for accelerometers required for military or aerospace applications is much larger, varying from 20,000 G (to measure acceleration during gun and ballistic munition launches), and to 10(exp -6) G, when used as guidance sensors (to measure attitude and position of a spacecraft). The presence of moving parts on the surface of chip is specific to MEMS, and particularly, to accelerometers. This characteristic brings new reliability issues to micromachined accelerometers, including cyclic fatigue cracking of polysilicon cantilevers and springs, mechanical stresses that are caused by packaging and contamination in the internal cavity of the package. Studies of fatigue cracks initiation and growth in polysilicon showed that the fatigue damage may influence MEMS device performance, and the presence of water vapor significantly enhances crack initiation and growth. Environmentally induced failures, particularly, failures due to thermal cycling and mechanical shock are considered as one of major reliability concerns in MEMS. These environmental conditions are also critical for space applications of the parts. For example, the Mars pathfinder mission had experienced 80 mechanical shock events during the pyrotechnic separation processes.

  10. Temperature insensitive all-fiber accelerometer using a photonic crystal fiber long-period grating interferometer

    NASA Astrophysics Data System (ADS)

    Zheng, Shijie; Zhu, Yinian; Krishnaswamy, Sridhar

    2012-04-01

    Fiber-optic accelerometers have attracted great attention in recent years due to the fact that they have many advantages over electrical counterparts because all-fiber accelerometers have the capabilities for multiplexing to reduce cabling and to transmit signals over a long distance. They are also immune to electromagnetic interference. We propose and develop a compact and robust photonic crystal fiber (PCF) Mach-Zehnder interferometer (MZI) that can be implemented as an accelerometer for measurements of vibration and displacement. To excite core mode to couple out with cladding modes, two long-period gratings (LPGs) with identical transmission spectra are needed to be written in an endless single-mode PCF using a CO2 laser. The first LPG can couple a part of core mode to several cladding modes. After the light beams travel at different speeds over a certain length of the core and cladding, the cladding modes will be recoupled back to the core when they meet the second LPG, resulting in interference between the core mode and cladding modes. Dynamic strain is introduced to the PCF-MZI fiber segment that is bonded onto a spring-mass system. The shift of interference fringe can be measured by a photodetector, and the transformed analog voltage signal is proportional to the acceleration of the sensor head. Based on simulations of the PCF-MZI accelerometer, we can get a sensitivity of ~ 0.08 nm/g which is comparable with fiber Bragg grating (FBG) accelerometers. The proposed accelerometer has a capability of temperature insensitivity; therefore, no thermal-compensation scheme is required. Experimental results indicate that the PCF-MZI accelerometer may be a good candidate sensor for applications in civil engineering infrastructure and aeronautical platforms.

  11. Cross-Cutting Relationships

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 25 August 2003

    The several linear cross-cutting grabens and collapse features observed in this THEMIS image illustrate the relative timing of a series of complex geologic processes as more recent events produce features that overlap and intersect older ones. Some impact craters are observed to be cut grabens, suggesting an older impact event compared to impact craters that appear fresh and unmodified.

    Image information: VIS instrument. Latitude 14.1, Longitude 236.3 East (123.7 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Low-Frequency Foam Insulator (LOFFI) Accelerometer Mount Characterization Results and Analysis for Phase I (FY2013)

    DTIC Science & Technology

    2014-06-01

    Low-Frequency Foam Insulator (LOFFI) Accelerometer Mount Characterization Results and Analysis for Phase I (FY2013) by Andrew Drysdale...Proving Ground, MD 21005-5068 ARL-TR-6977 June 2014 Low-Frequency Foam Insulator (LOFFI) Accelerometer Mount Characterization Results...4. TITLE AND SUBTITLE Low-Frequency Foam Insulator (LOFFI) Accelerometer Mount Characterization Results and Analysis for Phase I (FY2013) 5a

  13. Doubly Rotated Cut SAW Devices.

    DTIC Science & Technology

    1981-04-01

    locating promising angular ranges with properties superior to the singly rotated cuts now in existence. More detailed calculations follow to refinethe...superior to the singly rotated cuts now in existence. More detailed calculations followed to refine the angular coordinates in order to specify cuts...correlation between theory and experiment, all procedures followed as well as equipment used are discussed in paragraph 4. Paragraph 5 presents experimental

  14. [ANTHROPOMETRIC PARAMETERS' CUT-OFF POINTS FOR DIAGNOSIS OF SARCOPENIA].

    PubMed

    Canda Moreno, Alicia S

    2015-08-01

    Introducción: la sarcopenia es un síndrome caracterizado por baja masa muscular junto con pérdida de fuerza y/o disminución del rendimiento físico. Debido al envejecimiento de nuestra población, se ha producido un aumento de su prevalencia relacionada con la edad, a la que se suman otros factores causados por ciertas enfermedades o la malnutrición. Objetivo: ofrecer una herramienta para el diagnóstico de sarcopenia que determine de forma accesible la pérdida de masa muscular. Material y métodos: se realizó un protocolo antropométrico estandarizado en 883 varones y 506 mujeres, sanos y activos, de edad entre 20 y 39 años. Se calcularon los siguientes índices de desarrollo muscular: perímetros (brazo, antebrazo, muslo y pierna), perímetros corregidos (brazo, muslo y pierna), áreas musculares transversales (CSA de brazo, muslo y pierna) y masa muscular total (kg), en porcentaje (%) y relativa a la talla (kg/m2) mediante la ecuación de Lee. Se fijó como punto de corte el percentil 2,5 (rango inferior del 95% del intervalo de confianza) para las variables estudiadas. Resultados: se encontraron diferencias significativas (p < 0,0001) entre varones y mujeres en todos los indicadores. Los valores del punto de corte de diagnóstico de baja masa muscular fue en varones de 9,1 kg/m2, y en mujeres de 7,3 kg/m2. Y para las CSA (cm2) varón vs. mujer: brazo, 37,7 vs. 24,2; muslo, 154,3 vs. 115,8; y pierna, 78,8 vs. 60,2. Conclusiones: existe dimorfismo sexual que exige criterios diagnósticos diferenciados. La técnica antropométrica puede servir como screening de sarcopenia en el estudio de grandes poblaciones.

  15. Pyroshock data acquisition-recent developments using P/R and P/E accelerometers and isolators

    NASA Astrophysics Data System (ADS)

    Bateman, Vesta I.

    2002-05-01

    Mechanical isolators have been developed for piezoresistive and piezoelectric accelerometers to mitigate high frequency shocks before they reach the accelerometer because the high frequency pyroshocks may cause the accelerometer to resonate and/or break. Several commercial mechanically isolated accelerometers are available to the general public and their characteristics have been studied using Hopkinson bar test techniques. The in-axis response of these devices will be compared. Cross-axis response will be presented for one device. Additionally, pyroshock and ballistic shock measurements, performed by international organizations, will be presented for several isolators.

  16. Study on optimal surface property of WC-Co cutting tool for aluminium alloy cutting

    NASA Astrophysics Data System (ADS)

    Nizar, Mohd; Arimatsu, Naoya; Kawamitsu, Hiroshi; Takai, Kazuteru; Fukumoto, Masahiro

    2016-02-01

    The light weight property as well as high corrosion resistance of aluminium alloy has increased their demand especially in automobile industries. Aluminium alloy as a matter of fact has a low melting point and high ductility that severely adhere to the cutting tool surface and cause deterioration of chip evacuation. This problem often resulting in tools breakage. In this paper, in order to impart functions of anti-adhesion, we propose a technique by controlling the grinding marks micro texture on the tool surface by using the blast polishing treatment without any coating technologies. The results show that the tool which underwent polishing treatment reduces the cutting force as well as the aluminium adherence during the initial cutting process, and become worst as the process cutting continues. These results indicate that grinding mark texture improves the anti-adhesion by reducing the contact area during cutting and provide storage for the lubricant. In addition, too much polishing on the tool surface may remove these textures and resultantly worsen the tool performance.

  17. Electrostatic Accelerometer for the Gravity Recovery and Climate Experiment Follow-On Mission (GRACE FO)

    NASA Astrophysics Data System (ADS)

    Perrot, Eddy; Christophe, Bruno; Foulon, Bernard; Boulanger, Damien; Liorzou, Françoise; Lebat, Vincent

    2013-04-01

    The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, that will produce an accurate model of the Earth's gravity field variation providing global climatic data during five year at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link measuring the inter-satellites distance variation. Non-uniformities in the distribution of the Earth's mass cause the distance between the two satellites to vary. This variation is measured to recover gravity, after substracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing and manufacturing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics and the Front-End Electronic Unit) and the Interface Control Unit. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained in a center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the measurement output of the accelerometer. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with micro-gravity pendulum bench and with drops in ZARM catapult. Besides, a thermal stability is needed for the accelerometer core and front-end electronics to avoid bias and scale factor variation. To reach this stability, the sensor unit is enclosed in a thermal box designed by Astrium, spacecraft manufacturer. The accelerometers are designed to endure mechanical

  18. Evaluation of MEMS-Based Wireless Accelerometer Sensors in Detecting Gear Tooth Faults in Helicopter Transmissions

    NASA Technical Reports Server (NTRS)

    Lewicki, David George; Lambert, Nicholas A.; Wagoner, Robert S.

    2015-01-01

    The diagnostics capability of micro-electro-mechanical systems (MEMS) based rotating accelerometer sensors in detecting gear tooth crack failures in helicopter main-rotor transmissions was evaluated. MEMS sensors were installed on a pre-notched OH-58C spiral-bevel pinion gear. Endurance tests were performed and the gear was run to tooth fracture failure. Results from the MEMS sensor were compared to conventional accelerometers mounted on the transmission housing. Most of the four stationary accelerometers mounted on the gear box housing and most of the CI's used gave indications of failure at the end of the test. The MEMS system performed well and lasted the entire test. All MEMS accelerometers gave an indication of failure at the end of the test. The MEMS systems performed as well, if not better, than the stationary accelerometers mounted on the gear box housing with regards to gear tooth fault detection. For both the MEMS sensors and stationary sensors, the fault detection time was not much sooner than the actual tooth fracture time. The MEMS sensor spectrum data showed large first order shaft frequency sidebands due to the measurement rotating frame of reference. The method of constructing a pseudo tach signal from periodic characteristics of the vibration data was successful in deriving a TSA signal without an actual tach and proved as an effective way to improve fault detection for the MEMS.

  19. Application of Accelerometer Data to Mars Odyssey Aerobraking and Atmospheric Modeling

    NASA Technical Reports Server (NTRS)

    Tolson, R. H.; Keating, G. M.; George, B. E.; Escalera, P. E.; Werner, M. R.; Dwyer, A. M.; Hanna, J. L.

    2002-01-01

    Aerobraking was an enabling technology for the Mars Odyssey mission even though it involved risk due primarily to the variability of the Mars upper atmosphere. Consequently, numerous analyses based on various data types were performed during operations to reduce these risk and among these data were measurements from spacecraft accelerometers. This paper reports on the use of accelerometer data for determining atmospheric density during Odyssey aerobraking operations. Acceleration was measured along three orthogonal axes, although only data from the component along the axis nominally into the flow was used during operations. For a one second count time, the RMS noise level varied from 0.07 to 0.5 mm/s2 permitting density recovery to between 0.15 and 1.1 kg per cu km or about 2% of the mean density at periapsis during aerobraking. Accelerometer data were analyzed in near real time to provide estimates of density at periapsis, maximum density, density scale height, latitudinal gradient, longitudinal wave variations and location of the polar vortex. Summaries are given of the aerobraking phase of the mission, the accelerometer data analysis methods and operational procedures, some applications to determining thermospheric properties, and some remaining issues on interpretation of the data. Pre-flight estimates of natural variability based on Mars Global Surveyor accelerometer measurements proved reliable in the mid-latitudes, but overestimated the variability inside the polar vortex.

  20. An accelerometer-based system for elite athlete swimming performance analysis

    NASA Astrophysics Data System (ADS)

    Davey, Neil P.; Anderson, Megan E.; James, Daniel A.

    2005-02-01

    The measurement of sport specific performance characteristics is an important part of an athletes training and preparation for competition. Thus automated measurement, extraction and analysis of performance measures is desired and addressed in this paper. A tri-axial accelerometer based system was located on the lower back or swimmers to record acceleration profiles. The accelerometer system contained two ADXL202 bi-axial accelerometers positioned perpendicular to one another, and can store over 6 hours of data at 150Hz per channel using internal flash memory. The simultaneous collection of video and electronics touch pad timing was used to validate the algorithm results. Using the tri-axial accelerometer data, algorithms have been developed to derive lap times and stroke count. Comparison against electronic touch pad timing against accelerometer lap times has produced results with a typical error of better than +/-0.5 seconds. Video comparison of the stroke count algorithm for freestyle also produced results with an average error of +/-1 stroke. The developed algorithms have a higher level of reliability compared to hand timed and counted date that is commonly used during training.

  1. Characteristics of a piezoresistive accelerometer in high frequency, high shock environments

    SciTech Connect

    Bateman, V.I.; Davie, N.T.; Brown, F.A.

    1993-12-31

    The characteristics of a piezoresistive accelerometer in shock environments are being studied at Sandia National Laboratories in the Mechanical Shock Testing Laboratory. A Hopkinson bar capability has been developed to extend our understanding of the piezoresistive accelerometer with and without mechanical isolation in the high frequency, high shock environments where measurements are being made. Two different Hopkinson bar materials are being used: titanium and beryllium. The characteristics of the piezoresistive accelerometer for frequencies of DC-10 kHz and shock magnitudes of up to 4,000 g as determined from measurements with a titanium Hopkinson bar are presented. The SNL uniaxial shock isolation technique has demonstrated acceptable characteristics for a temperature range of {minus}50{degree}F to +186{degree}F and a frequency bandwidth of DC to 10 kHz. These characteristics have been verified by the calibration of the Hopkinson bar used for accelerometer testing. The beryllium Hopkinson bar configuration is described. Preliminary characteristics of the piezoresistive accelerometer at a nominal shock level of 17,000 g for a frequency range of DC-50 kHz are presented.

  2. Comparison of IPAQ-SF and Two Other Physical Activity Questionnaires with Accelerometer in Adolescent Boys

    PubMed Central

    Mäestu, Jarek; Lätt, Evelin; Jürimäe, Jaak; Vainik, Uku

    2017-01-01

    Self-report measures of physical activity (PA) are easy to use and popular but their reliability is often questioned. Therefore, the general aim of the present study was to investigate the association of PA questionnaires with accelerometer derived PA, in a sample of adolescent boys. In total, 191 pubertal boys (mean age 14.0 years) completed three self-report questionnaires and wore an accelerometer (ActiGraph GT1M) for 7 consecutive days. The PA questionnaires were: International Physical Activity Questionnaire-Short Form (IPAQ-SF), Tartu Physical Activity Questionnaire (TPAQ), and the Inactivity subscale from Domain-Specific Impulsivity (DSI) scale. All three questionnaires were significantly correlated with accelerometer derived MVPA: the correlations were 0.31 for the IPAQ-SF MVPA, 0.34 for the TPAQ MVPA and -0.29 for the DSI Inactivity scale. Nevertheless, none of the questionnaires can be used as a reliable individual-level estimate of MVPA in male adolescents. The boys underreported their MVPA in IPAQ-SF as compared to accelerometer-derived MVPA (respective averages 43 and 56 minutes); underreporting was more marked in active boys with average daily MVPA at least 60 minutes, and was not significant in less active boys. Conversely, MVPA index from TPAQ overestimated the MVPA in less active boys but underestimated it in more active boys. The sedentary time reported in IPAQ-SF was an underestimate as compared to accelerometer-derived sedentary time (averages 519 and 545 minutes, respectively). PMID:28056080

  3. Measurement Method of Magnetic Field for the Wire Suspended Micro-Pendulum Accelerometer

    PubMed Central

    Lu, Yongle; Li, Leilei; Hu, Ning; Pan, Yingjun; Ren, Chunhua

    2015-01-01

    Force producer is one of the core components of a Wire Suspended Micro-Pendulum Accelerometer; and the stability of permanent magnet in the force producer determines the consistency of the acceleration sensor’s scale factor. For an assembled accelerometer; direct measurement of magnetic field strength is not a feasible option; as the magnetometer probe cannot be laid inside the micro-space of the sensor. This paper proposed an indirect measurement method of the remnant magnetization of Micro-Pendulum Accelerometer. The measurement is based on the working principle of the accelerometer; using the current output at several different scenarios to resolve the remnant magnetization of the permanent magnet. Iterative Least Squares algorithm was used for the adjustment of the data due to nonlinearity of this problem. The calculated remnant magnetization was 1.035 T. Compared to the true value; the error was less than 0.001 T. The proposed method provides an effective theoretical guidance for measuring the magnetic field of the Wire Suspended Micro-Pendulum Accelerometer; correcting the scale factor and temperature influence coefficients; etc. PMID:25871721

  4. Measurement method of magnetic field for the wire suspended micro-pendulum accelerometer.

    PubMed

    Lu, Yongle; Li, Leilei; Hu, Ning; Pan, Yingjun; Ren, Chunhua

    2015-04-13

    Force producer is one of the core components of a Wire Suspended Micro-Pendulum Accelerometer; and the stability of permanent magnet in the force producer determines the consistency of the acceleration sensor's scale factor. For an assembled accelerometer; direct measurement of magnetic field strength is not a feasible option; as the magnetometer probe cannot be laid inside the micro-space of the sensor. This paper proposed an indirect measurement method of the remnant magnetization of Micro-Pendulum Accelerometer. The measurement is based on the working principle of the accelerometer; using the current output at several different scenarios to resolve the remnant magnetization of the permanent magnet. Iterative Least Squares algorithm was used for the adjustment of the data due to nonlinearity of this problem. The calculated remnant magnetization was 1.035 T. Compared to the true value; the error was less than 0.001 T. The proposed method provides an effective theoretical guidance for measuring the magnetic field of the Wire Suspended Micro-Pendulum Accelerometer; correcting the scale factor and temperature influence coefficients; etc.

  5. An integrated digital silicon micro-accelerometer with MOSFET-type sensing elements

    NASA Astrophysics Data System (ADS)

    Yee, Youngjoo; Bu, Jong Uk; Chun, Kukjin; Lee, Joong-Won

    2000-09-01

    A fully digital integrated accelerometer having a new sensing element is designed and fabricated based on CMOS processes and micromachining. The sensing elements of this accelerometer are constructed on the bulk silicon proof mass with metal air-gap MOSFETs (MAMOS) whose drain current is dependent on the applied acceleration. A current-controlled oscillator converts the change of this drain current to a digital pulse train. A 20-bit synchronous binary counter is monolithically integrated to digitize the output pulse of the oscillator. A bulk micromachined silicon proof mass provides perfect electrical isolation of the MOSFET sensing elements from a peripheral CMOS readout circuit. The suspension springs of this accelerometer are formed from thick MEMS (microelectromechanical systems) polysilicon. A CMOS compatible doping and annealing process for the MEMS polysilicon is developed to optimize the trade-off between the mechanical properties and the electrical requirements. The shift in the overall device characteristics of CMOS circuitry integrated with MEMS polysilicon is well below 5% of those fabricated by a standard CMOS process. Using the slightly modified 1.5 µm CMOS circuit process followed by an anisotropic silicon etch, an integrated digital silicon accelerometer is fabricated. The measured sensitivity of the fabricated MAMOS accelerometer is 63 kHz G-1.

  6. Comparison between accelerometer and laser vibrometer to measure traffic-excited vibrations on bridges

    NASA Astrophysics Data System (ADS)

    Gioffre, M.; Gusella, V.; Marsili, Roberto; Rossi, Gianluca L.

    2000-05-01

    The use of accelerometer based measurement techniques for evaluating bridge forced vibrations or to perform bridge modal analysis is well established. Some of the goals of this experimental approach and typical results are here reviewed. It is well known to all researchers who have experience in vibration measurements that values of acceleration amplitude can be very low at low frequencies and that a limitation to the use of accelerometer can be due to the threshold parameter of this kind of transducer. Under this condition the measurement of displacement seems more appropriate. On the other hand laser vibrometer systems detect relative displacements as opposed to the absolute measures of accelerometers. In this paper the results of some in field measurements on a highway little bridge, excited by traffic, under normal operating conditions, are analyzed. Vibrations have been measured simultaneously by a typical accelerometer for civil structures and by a laser vibrometer equipped with a fringe counter board in terms of velocity and displacements. The accelerations calculated from the laser vibrometer signals and the one directly measured by the accelerometer has been compared. The advantages of the use of a laser vibrometer at low frequency are relevant and it appears possible to open up new possibility to analyze bridge loads in operating conditions, monitoring bridge health state, predict fatigue life and improve the bridge design.

  7. Feasibility of frequency-modulated wireless transmission for a multi-purpose MEMS-based accelerometer.

    PubMed

    Sabato, Alessandro; Feng, Maria Q

    2014-09-05

    Recent advances in the Micro Electro-Mechanical System (MEMS) technology have made wireless MEMS accelerometers an attractive tool for Structural Health Monitoring (SHM) of civil engineering structures. To date, sensors' low sensitivity and accuracy--especially at very low frequencies--have imposed serious limitations for their application in monitoring large-sized structures. Conventionally, the MEMS sensor's analog signals are converted to digital signals before radio-frequency (RF) wireless transmission. The conversion can cause a low sensitivity to the important low-frequency and low-amplitude signals. To overcome this difficulty, the authors have developed a MEMS accelerometer system, which converts the sensor output voltage to a frequency-modulated signal before RF transmission. This is achieved by using a Voltage to Frequency Conversion (V/F) instead of the conventional Analog to Digital Conversion (ADC). In this paper, a prototype MEMS accelerometer system is presented, which consists of a transmitter and receiver circuit boards. The former is equipped with a MEMS accelerometer, a V/F converter and a wireless RF transmitter, while the latter contains an RF receiver and a F/V converter for demodulating the signal. The efficacy of the MEMS accelerometer system in measuring low-frequency and low-amplitude dynamic responses is demonstrated through extensive laboratory tests and experiments on a flow-loop pipeline.

  8. Feasibility of Frequency-Modulated Wireless Transmission for a Multi-Purpose MEMS-Based Accelerometer

    PubMed Central

    Sabato, Alessandro; Feng, Maria Q.

    2014-01-01

    Recent advances in the Micro Electro-Mechanical System (MEMS) technology have made wireless MEMS accelerometers an attractive tool for Structural Health Monitoring (SHM) of civil engineering structures. To date, sensors' low sensitivity and accuracy—especially at very low frequencies—have imposed serious limitations for their application in monitoring large-sized structures. Conventionally, the MEMS sensor's analog signals are converted to digital signals before radio-frequency (RF) wireless transmission. The conversion can cause a low sensitivity to the important low-frequency and low-amplitude signals. To overcome this difficulty, the authors have developed a MEMS accelerometer system, which converts the sensor output voltage to a frequency-modulated signal before RF transmission. This is achieved by using a Voltage to Frequency Conversion (V/F) instead of the conventional Analog to Digital Conversion (ADC). In this paper, a prototype MEMS accelerometer system is presented, which consists of a transmitter and receiver circuit boards. The former is equipped with a MEMS accelerometer, a V/F converter and a wireless RF transmitter, while the latter contains an RF receiver and a F/V converter for demodulating the signal. The efficacy of the MEMS accelerometer system in measuring low-frequency and low-amplitude dynamic responses is demonstrated through extensive laboratory tests and experiments on a flow-loop pipeline. PMID:25198003

  9. The timing of scour and fill in a gravel-bedded river measured with buried accelerometers

    USGS Publications Warehouse

    Gendaszek, Andrew S.; Magirl, Christopher S.; Czuba, Christiana R.; Konrad, Christopher P.

    2013-01-01

    A device that measures the timing of streambed scour and the duration of sediment mobilization at specific depths of a streambed was developed using data-logging accelerometers placed within the gravel substrate of the Cedar River, Washington, USA. Each accelerometer recorded its orientation every 20 min and remained stable until the surrounding gravel matrix mobilized as sediment was transported downstream and scour reached the level of the accelerometer. The accelerometer scour monitors were deployed at 26 locations in salmon-spawning habitat during the 2010–2011 flood season to record when the streambed was scoured to the depth of typical egg-pocket deposition. Scour was recorded at one location during a moderate high-flow event (65 m3/s; 1.25–1.5-year recurrence interval) and at 17 locations during a larger high-flow event (159 m3/s; 7-year recurrence interval). Accelerometer scour monitors recorded periods of intermittent sediment mobilization and stability within a high-flow event providing insight into the duration of scour. Most scour was recorded during the rising limb and at the peak of a flood hydrograph, though some scour occurred during sustained high flows following the peak of the flood hydrograph.

  10. Validation of the Actical Accelerometer in Multiethnic Preschoolers: The Children's Healthy Living (CHL) Program

    PubMed Central

    Ettienne, Reynolette; Li, Fenfang; Su, Yuhua; McGlone, Katalina; Luick, Bret; Tachibana, Alvin; Carran, Christina; Mercado, Jobel; Novotny, Rachel

    2016-01-01

    This study aimed to determine the validity and reliability of the Actical accelerometer for measuring physical activity (PA) in preschool children of mixed ethnicity, compared with direct observation via a modified System for Observing Fitness Instruction Time (SOFIT) protocol and proxy parental reports (PA Logs). Fifty children in Hawai‘i wore wrist-mounted accelerometers for two 7-day periods with a washout period between each week. Thirty children were concurrently observed using SOFIT. Parents completed PA Logs for three days. Reliability and validity were measured by intra-class correlation coefficient and proportions of agreement concurrently. There was slight agreement (proportion of agreement: 82%; weighted Kappa=.17, P <.001) between the accelerometer and SOFIT as well as between the accelerometer and the PA Logs (proportions of agreement: 40%; weighted Kappa=0.15, P <.001). PA logs underestimated the PA levels of the children, while the Actical was found to be valid and reliable for estimating PA levels of multiethnic, mixed ethnicity preschoolers. These findings suggest that accelerometers can be objective, valid, and accurate physical activity assessment tools compared to conventional PA logs and subjective reports of activity for preschool children of mixed ethnicity. PMID:27099804

  11. Ground Based Investigation of Electrostatic Accelerometer in HUST

    NASA Astrophysics Data System (ADS)

    Bai, Y.; Zhou, Z.

    2013-12-01

    High-precision electrostatic accelerometers with six degrees of freedom (DOF) acceleration measurement were successfully used in CHAMP, GRACE and GOCE missions which to measure the Earth's gravity field. In our group, space inertial sensor based on the capacitance transducer and electrostatic control technique has been investigated for test of equivalence principle (TEPO), searching non-Newtonian force in micrometer range, and satellite Earth's field recovery. The significant techniques of capacitive position sensor with the noise level at 2×10-7pF/Hz1/2 and the μV/Hz1/2 level electrostatic actuator are carried out and all the six servo loop controls by using a discrete PID algorithm are realized in a FPGA device. For testing on ground, in order to compensate one g earth's gravity, the fiber torsion pendulum facility is adopt to measure the parameters of the electrostatic controlled inertial sensor such as the resolution, and the electrostatic stiffness, the cross couple between different DOFs. A short distance and a simple double capsule equipment the valid duration about 0.5 second is set up in our lab for the free fall tests of the engineering model which can directly verify the function of six DOF control. Meanwhile, high voltage suspension method is also realized and preliminary results show that the horizontal axis of acceleration noise is about 10-8m/s2/Hz1/2 level which limited mainly by the seismic noise. Reference: [1] Fen Gao, Ze-Bing Zhou, Jun Luo, Feasibility for Testing the Equivalence Principle with Optical Readout in Space, Chin. Phys. Lett. 28(8) (2011) 080401. [2] Z. Zhu, Z. B. Zhou, L. Cai, Y. Z. Bai, J. Luo, Electrostatic gravity gradiometer design for the advanced GOCE mission, Adv. Sp. Res. 51 (2013) 2269-2276. [3] Z B Zhou, L Liu, H B Tu, Y Z Bai, J Luo, Seismic noise limit for ground-based performance measurements of an inertial sensor using a torsion balance, Class. Quantum Grav. 27 (2010) 175012. [4] H B Tu, Y Z Bai, Z B Zhou, L Liu, L

  12. Using Accelerometer and Gyroscopic Measures to Quantify Postural Stability

    PubMed Central

    Alberts, Jay L.; Hirsch, Joshua R.; Koop, Mandy Miller; Schindler, David D.; Kana, Daniel E.; Linder, Susan M.; Campbell, Scott; Thota, Anil K.

    2015-01-01

    Context Force platforms and 3-dimensional motion-capture systems provide an accurate method of quantifying postural stability. Substantial cost, space, time to administer, and need for trained personnel limit widespread use of biomechanical techniques in the assessment of postural stability in clinical or field environments. Objective To determine whether accelerometer and gyroscope data sampled from a consumer electronics device (iPad2) provide sufficient resolution of center-of-gravity (COG) movements to accurately quantify postural stability in healthy young people. Design Controlled laboratory study. Setting Research laboratory in an academic medical center. Patients or Other Participants A total of 49 healthy individuals (age = 19.5 ± 3.1 years, height = 167.7 ± 13.2 cm, mass = 68.5 ± 17.5 kg). Intervention(s) Participants completed the NeuroCom Sensory Organization Test (SOT) with an iPad2 affixed at the sacral level. Main Outcome Measure(s) Primary outcomes were equilibrium scores from both systems and the time series of the angular displacement of the anteroposterior COG sway during each trial. A Bland-Altman assessment for agreement was used to compare equilibrium scores produced by the NeuroCom and iPad2 devices. Limits of agreement was defined as the mean bias (NeuroCom − iPad) ± 2 standard deviations. Mean absolute percentage error and median difference between the NeuroCom and iPad2 measurements were used to evaluate how closely the real-time COG sway measured by the 2 systems tracked each other. Results The limits between the 2 devices ranged from −0.5° to 0.5° in SOT condition 1 to −2.9° to 1.3° in SOT condition 5. The largest absolute value of the measurement error within the 95% confidence intervals for all conditions was 2.9°. The mean absolute percentage error analysis indicated that the iPad2 tracked NeuroCom COG with an average error ranging from 5.87% to 10.42% of the NeuroCom measurement across SOT conditions. Conclusions The i

  13. Cutting and Self-Harm

    MedlinePlus

    ... sad Cutting and self-harm Cutting and self-harm Self-harm, sometimes called self-injury, is when a person ... about how one girl helps herself not self-harm. What are signs of self-injury in others? ...

  14. How to Cut Publications Costs.

    ERIC Educational Resources Information Center

    Carter, Virginia L., Ed.; Alberger, Patricia A., Ed.

    This handbook on how to cut costs in college publications contains the following articles: "Stretching Your Publications Dollar: The Basics," by Kelvin J. Arden and William J. Whalen; "How to Print Cheaper," by M. Frederic Volkmann; "How Your Colleagues Cut Costs," by Robert S. Topor; "Printing Specifications: Writing Them Right," by M. Frederic…

  15. Corner-cutting mining assembly

    DOEpatents

    Bradley, John A.

    1983-01-01

    A mining assembly includes a primary rotary cutter mounted on one end of a support shaft and four secondary rotary cutters carried on the same support shaft and positioned behind the primary cutters for cutting corners in the hole cut by the latter.

  16. Composite structure for cutting tools

    SciTech Connect

    Radd, F.J.; Haden, E.L.

    1984-01-01

    A cutting tool comprises a compact bundle of elongated, substantially cylindrical fibers or rods formed from a cemented metal carbide material. The bundle of fibers is shrink-fitted within a metal collar to form a long-wearing cutting tool.

  17. Tubing and cable cutting tool

    NASA Technical Reports Server (NTRS)

    Mcsmith, D. D.; Richardson, J. I. (Inventor)

    1984-01-01

    A hand held hydraulic cutting tool was developed which is particularly useful in deactivating ejection seats in military aircraft rescue operations. The tool consists primarily of a hydraulic system composed of a fluid reservoir, a pumping piston, and an actuator piston. Mechanical cutting jaws are attached to the actuator piston rod. The hydraulic system is controlled by a pump handle. As the pump handle is operated the actuator piston rod is forced outward and thus the cutting jaws are forced together. The frame of the device is a flexible metal tubing which permits easy positioning of the tool cutting jaws in remote and normally inaccessible locations. Bifurcated cutting edges ensure removal of a section of the tubing or cable to thereby reduce the possibility of accidental reactivation of the tubing or cable being severed.

  18. Specific Energy as an Index to Identify the Critical Failure Mode Transition Depth in Rock Cutting

    NASA Astrophysics Data System (ADS)

    He, Xianqun; Xu, Chaoshui

    2016-04-01

    Rock cutting typically involves driving a rigid cutter across the rock surface at certain depth of cut and is used to remove rock material in various engineering applications. It has been established that there exist two distinct failure modes in rock cutting, i.e. ductile mode and brittle mode. The ductile mode takes precedence when the cut is shallow and the increase in the depth of cut leads to rock failure gradually shifted to brittle-dominant mode. The threshold depth or the critical transition depth, at which rock failure under cutting changes from the ductile to the brittle mode, is associated with not only the rock properties but also the cutting operational parameters and the understanding of this threshold is important to optimise the tool design and operational parameters. In this study, a new method termed the specific cutting energy transition model is proposed from an energy perspective which is demonstrated to be much more effective in identifying the critical transition depth compared with existing approaches. In the ductile failure cutting mode, the specific cutting energy is found to be independent of the depth of cut; but in the brittle failure cutting mode, the specific cutting energy is found to be dependent on the depth of cut following a power-law relationship. The critical transition depth is identified as the intersection point between these two relationships. Experimental tests on two types of rocks with different combinations of cutting velocity, depth of cut and back rake angle are conducted and the application of the proposed model on these cutting datasets has demonstrated that the model can provide a very effective tool to analyse the cutting mechanism and to identify the critical transition depth.

  19. Note: A balloon-borne accelerometer technique for measuring atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Marlton, Graeme J.; Giles Harrison, R.; Nicoll, Keri A.; Williams, Paul D.

    2015-01-01

    A weather balloon and its suspended instrument package behave like a pendulum with a moving pivot. This dynamical system is exploited here for the detection of atmospheric turbulence. By adding an accelerometer to the instrument package, the size of the swings induced by atmospheric turbulence can be measured. In test flights, strong turbulence has induced accelerations greater than 5g, where g = 9.81 m s-2. Calibration of the accelerometer data with a vertically orientated lidar has allowed eddy dissipation rate values of between 10-3 and 10-2 m2 s-3 to be derived from the accelerometer data. The novel use of a whole weather balloon and its adapted instrument package can be used as a new instrument to make standardized in situ measurements of turbulence.

  20. In-Flight Estimation of Center of Gravity Position Using All-Accelerometers

    PubMed Central

    Al-Rawashdeh, Yazan Mohammad; Elshafei, Moustafa; Al-Malki, Mohammad Fahad

    2014-01-01

    Changing the position of the Center of Gravity (CoG) for an aerial vehicle is a challenging part in navigation, and control of such vehicles. In this paper, an all-accelerometers-based inertial measurement unit is presented, with a proposed method for on-line estimation of the position of the CoG. The accelerometers' readings are used to find and correct the vehicle's angular velocity and acceleration using an Extended Kalman Filter. Next, the accelerometers' readings along with the estimated angular velocity and acceleration are used in an identification scheme to estimate the position of the CoG and the vehicle's linear acceleration. The estimated position of the CoG and motion measurements can then be used to update the control rules to achieve better trim conditions for the air vehicle. PMID:25244585

  1. Design of a Piezoelectric Accelerometer with High Sensitivity and Low Transverse Effect.

    PubMed

    Tian, Bian; Liu, Hanyue; Yang, Ning; Zhao, Yulong; Jiang, Zhuangde

    2016-09-26

    In order to meet the requirements of cable fault detection, a new structure of piezoelectric accelerometer was designed and analyzed in detail. The structure was composed of a seismic mass, two sensitive beams, and two added beams. Then, simulations including the maximum stress, natural frequency, and output voltage were carried out. Moreover, comparisons with traditional structures of piezoelectric accelerometer were made. To verify which vibration mode is the dominant one on the acceleration and the space between the mass and glass, mode analysis and deflection analysis were carried out. Fabricated on an n-type single crystal silicon wafer, the sensor chips were wire-bonged to printed circuit boards (PCBs) and simply packaged for experiments. Finally, a vibration test was conducted. The results show that the proposed piezoelectric accelerometer has high sensitivity, low resonance frequency, and low transverse effect.

  2. Design of a Piezoelectric Accelerometer with High Sensitivity and Low Transverse Effect

    PubMed Central

    Tian, Bian; Liu, Hanyue; Yang, Ning; Zhao, Yulong; Jiang, Zhuangde

    2016-01-01

    In order to meet the requirements of cable fault detection, a new structure of piezoelectric accelerometer was designed and analyzed in detail. The structure was composed of a seismic mass, two sensitive beams, and two added beams. Then, simulations including the maximum stress, natural frequency, and output voltage were carried out. Moreover, comparisons with traditional structures of piezoelectric accelerometer were made. To verify which vibration mode is the dominant one on the acceleration and the space between the mass and glass, mode analysis and deflection analysis were carried out. Fabricated on an n-type single crystal silicon wafer, the sensor chips were wire-bonged to printed circuit boards (PCBs) and simply packaged for experiments. Finally, a vibration test was conducted. The results show that the proposed piezoelectric accelerometer has high sensitivity, low resonance frequency, and low transverse effect. PMID:27681734

  3. Implementation of an iPhone as a wireless accelerometer for quantifying gait characteristics.

    PubMed

    Lemoyne, Robert; Mastroianni, Timothy; Cozza, Michael; Coroian, Cristian; Grundfest, Warren

    2010-01-01

    The capacity to quantify and evaluate gait beyond the general confines of a clinical environment under effectively autonomous conditions may alleviate rampant strain on limited and highly specialized medical resources. An iPhone consists of a three dimensional accelerometer subsystem with highly robust and scalable software applications. With the synthesis of the integral iPhone features, an iPhone application, which constitutes a wireless accelerometer system for gait quantification and analysis, has been tested and evaluated in an autonomous environment. The acquired gait cycle data was transmitted wireless and through email for subsequent post-processing in a location remote to the location where the experiment was conducted. The iPhone application functioning as a wireless accelerometer for the acquisition of gait characteristics has demonstrated sufficient accuracy and consistency.

  4. Activity recognition in planetary navigation field tests using classification algorithms applied to accelerometer data.

    PubMed

    Song, Wen; Ade, Carl; Broxterman, Ryan; Barstow, Thomas; Nelson, Thomas; Warren, Steve

    2012-01-01

    Accelerometer data provide useful information about subject activity in many different application scenarios. For this study, single-accelerometer data were acquired from subjects participating in field tests that mimic tasks that astronauts might encounter in reduced gravity environments. The primary goal of this effort was to apply classification algorithms that could identify these tasks based on features present in their corresponding accelerometer data, where the end goal is to establish methods to unobtrusively gauge subject well-being based on sensors that reside in their local environment. In this initial analysis, six different activities that involve leg movement are classified. The k-Nearest Neighbors (kNN) algorithm was found to be the most effective, with an overall classification success rate of 90.8%.

  5. Cable force monitoring system of cable stayed bridges using accelerometers inside mobile smart phone

    NASA Astrophysics Data System (ADS)

    Zhao, Xuefeng; Yu, Yan; Hu, Weitong; Jiao, Dong; Han, Ruicong; Mao, Xingquan; Li, Mingchu; Ou, Jinping

    2015-03-01

    Cable force is one of the most important parameters in structural health monitoring system integrated on cable stayed bridges for safety evaluation. In this paper, one kind of cable force monitoring system scheme was proposed. Accelerometers inside mobile smart phones were utilized for the acceleration monitoring of cable vibration. Firstly, comparative tests were conducted in the lab. The test results showed that the accelerometers inside smartphones can detect the cable vibration, and then the cable force can be obtained. Furthermore, there is good agreement between the monitoring results of different kinds of accelerometers. Finally, the proposed cable force monitoring system was applied on one cable strayed bridge structure, the monitoring result verified the feasibility of the monitoring system.

  6. Cutting forces in orthogonal cutting of unidirectional GFRP composites

    SciTech Connect

    Caprino, G.; Nele, L.

    1996-07-01

    The results of orthogonal cutting tests carried out on unidirectional glass fiber reinforced plastic composites, using HSS tools, are presented and discussed. During the tests, performed on a milling machine at very low cutting speed to avoid thermal effects, the cutting speed was held constant and parallel to the fiber direction. Three parameters, namely the tool rake angle {alpha}, the tool relief angle {gamma}, and the depth of cut t, were varied. According to the experimental results, the horizontal force per unit width, F{sub hu}, undergoes a dramatic decrease, never verified for metals, with increasing {alpha}. Besides, F{sub hu} is only negligibly affected by the relief angle, and linearly increases with t. Similarly to metals, an effect of the depth of cut on the specific energy (size effect) is found also for composites. However, the presented results indicate that the size effect can be analytically modeled in a simple way in the case of composites. The vertical force per unit width, F{sub vu}, exhibits a marked reduction when the relief angle is increased. F{sub vu} is also very sensitive to the rake angle: the lower {alpha}, the higher is F{sub vu}. It is shown that this behavior probably reflects a strong influence of the rake angle on the forces developing at the flank. A linear dependence of the vertical force on the depth of cut is also demonstrated. Finally, the experimental data are utilized to obtain empirical formulae, allowing an approximate evaluation of cutting forces.

  7. Machine Learning Methods for Classifying Human Physical Activity from On-Body Accelerometers

    PubMed Central

    Mannini, Andrea; Sabatini, Angelo Maria

    2010-01-01

    The use of on-body wearable sensors is widespread in several academic and industrial domains. Of great interest are their applications in ambulatory monitoring and pervasive computing systems; here, some quantitative analysis of human motion and its automatic classification are the main computational tasks to be pursued. In this paper, we discuss how human physical activity can be classified using on-body accelerometers, with a major emphasis devoted to the computational algorithms employed for this purpose. In particular, we motivate our current interest for classifiers based on Hidden Markov Models (HMMs). An example is illustrated and discussed by analysing a dataset of accelerometer time series. PMID:22205862

  8. Design, Simulation and Optimisation of a Fibre-optic 3D Accelerometer

    NASA Astrophysics Data System (ADS)

    Yang, Zhen; Fang, Xiao-Yong; Zhou, Yan; Li, Ya-lin; Yuan, Jie; Cao, Mao-Sheng

    2013-07-01

    Using an inertia pendulum comprised of two prisms, flexible beams and an elastic flake, we present a novel fibre-optic 3D accelerometer design. The total reverse reflection of the cube-corner prism and the spectroscopic property of an orthogonal holographic grating enable the measurement of the two transverse components of the 3D acceleration simultaneously, while the longitudinal component can be determined from the elastic deformation of the flake. Due to optical interferometry, this sensor may provide a wider range, higher sensitivity and better resolving power than other accelerometers. Moreover, we use finite element analysis to study the performance and to optimise the structural design of the sensor.

  9. Physical Activity and Adiposity Markers at Older Ages: Accelerometer Vs Questionnaire Data

    PubMed Central

    Sabia, Séverine; Cogranne, Pol; van Hees, Vincent T.; Bell, Joshua A.; Elbaz, Alexis; Kivimaki, Mika; Singh-Manoux, Archana

    2015-01-01

    Objective Physical activity is critically important for successful aging, but its effect on adiposity markers at older ages is unclear as much of the evidence comes from self-reported data on physical activity. We assessed the associations of questionnaire-assessed and accelerometer-assessed physical activity with adiposity markers in older adults. Design/Setting/Participants This was a cross-sectional study on 3940 participants (age range 60-83 years) of the Whitehall II study who completed a 20-item physical activity questionnaire and wore a wrist-mounted accelerometer for 9 days in 2012 and 2013. Measurements Total physical activity was estimated using metabolic equivalent hours/week for the questionnaire and mean acceleration for the accelerometer. Time spent in moderate-and-vigorous physical activity (MVPA) was also assessed by questionnaire and accelerometer. Adiposity assessment included body mass index, waist circumference, and fat mass index. Fat mass index was calculated as fat mass/height² (kg/m²), with fat mass estimated using bioimpedance. Results Greater total physical activity was associated with lower adiposity for all adiposity markers in a dose-response manner. In men, the strength of this association was 2.4 to 2.8 times stronger with the accelerometer than with questionnaire data. In women, it was 1.9 to 2.3 times stronger. For MVPA, questionnaire data in men suggested no further benefit for adiposity markers past 1 hour/week of activity. This was not the case for accelerometer-assessed MVPA where, for example, compared with men undertaking <1 hour/week of accelerometer-assessed MVPA, waist circumference was 3.06 (95% confidence interval 2.06–4.06) cm lower in those performing MVPA 1–2.5 hours/week, 4.69 (3.47–5.91) cm lower in those undertaking 2.5–4 hours/week, and 7.11 (5.93–8.29) cm lower in those performing ≥4 hours/week. Conclusions The association of physical activity with adiposity markers in older adults was

  10. High-resolution width-modulated pulse rebalance electronics for strapdown gyroscopes and accelerometers

    NASA Technical Reports Server (NTRS)

    Kennedy, E. J.; Blalock, T. V.; Bryan, W. L.; Rush, K.

    1974-01-01

    Three different rebalance electronic loops were designed, implemented, and evaluated. The loops were width-modulated binary types using a 614.4 kHz keying signal; they were developed to accommodate the following three inertial sensors with the indicated resolution values: (1) Kearfott 2412 accelerometer - resolution = 260 micro-g/data pulse, (2) Honeywell GG334 gyroscope - resolution = 3.9 milli-arc-sec/data pulse, (3) Kearfott 2401-009 accelerometer - resolution = 144 milli-g/data pulse. Design theory, details of the design implementation, and experimental results for each loop are presented.

  11. Linear Acceleration Measurement Utilizing Inter-Instrument Synchronization: A Comparison between Accelerometers and Motion-Based Tracking Approaches

    ERIC Educational Resources Information Center

    Callaway, Andrew J.; Cobb, Jon E.

    2012-01-01

    Where as video cameras are a reliable and established technology for the measurement of kinematic parameters, accelerometers are increasingly being employed for this type of measurement due to their ease of use, performance, and comparatively low cost. However, the majority of accelerometer-based studies involve a single channel due to the…

  12. Note on recursion relations for the Q -cut representation

    NASA Astrophysics Data System (ADS)

    Feng, Bo; He, Song; Huang, Rijun; Luo, Ming-xing

    2017-01-01

    In this note, we study the Q -cut representation by combining it with BCFW deformation. As a consequence, the one-loop integrand is expressed in terms of a recursion relation, i.e., n-point one-loop integrand is constructed using tree-level amplitudes and m-point one-loop integrands with m ≤ n - 1. By giving explicit examples, we show that the integrand from the recursion relation is equivalent to that from Feynman diagrams or the original Q -cut construction, up to scale free terms.

  13. One cutting plane algorithm using auxiliary functions

    NASA Astrophysics Data System (ADS)

    Zabotin, I. Ya; Kazaeva, K. E.

    2016-11-01

    We propose an algorithm for solving a convex programming problem from the class of cutting methods. The algorithm is characterized by the construction of approximations using some auxiliary functions, instead of the objective function. Each auxiliary function bases on the exterior penalty function. In proposed algorithm the admissible set and the epigraph of each auxiliary function are embedded into polyhedral sets. In connection with the above, the iteration points are found by solving linear programming problems. We discuss the implementation of the algorithm and prove its convergence.

  14. Cutting Head for Ultrasonic Lithotripsy

    NASA Technical Reports Server (NTRS)

    Angulo, E. D.; Goodfriend, R.

    1987-01-01

    Kidney stones lodged in urinary tract disintegrated with increased safety and efficiency by cutting head attached to end of vibrated wire probe. Aligns probe with stone and enables probe to vibrate long enough to disintegrate stone. Design of cutting head reduces risk of metal-fatigue-induced breakage of probe tip leaving metal fragments in urinary tract. Teeth of cutting head both seat and fragment kidney stone, while extension of collar into catheter lessens mechanical strain in probe wire, increasing probe life and lessening danger of in situ probe breakage.

  15. Electrostatic Accelerometer for the Gravity Recovery and Climate Experiment Follow-On Mission (GRACE FO)

    NASA Astrophysics Data System (ADS)

    Lebat, V.; Foulon, B.; Christophe, B.

    2013-12-01

    The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, that will produce an accurate model of the Earth's gravity field variation providing global climatic data during five year at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link measuring the inter-satellites distance variation. Non-uniformities in the distribution of the Earth's mass cause the distance between the two satellites to vary. This variation is measured to recover gravity, after subtracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing, manufacturing and testing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics and the Front-End Electronic Unit) and the Interface Control Unit. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained in a center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the measurement output of the accelerometer. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with micro-gravity pendulum bench and with drops in ZARM catapult. Besides, a thermal stability is needed for the accelerometer core and front-end electronics to avoid bias and scale factor variation, and reached by a thermal box designed by Astrium, spacecraft manufacturer. The accelerometers are designed to endure the launch vibrations and the thermal environment at

  16. Using Tri-Axial Accelerometers to Assess the Dynamic Control of Head Posture During Gait

    NASA Technical Reports Server (NTRS)

    Lawrence, John H., III

    2003-01-01

    Long duration spaceflight is known to cause a variety of biomedical stressors to the astronaut. One of the more functionally destabilizing effects of spaceflight involves microgravity-induced changes in vestibular or balance control. Balance control requires the integration of the vestibular, visual, and proprioceptive systems. In the microgravity environment, the normal gravity vector present on Earth no longer serves as a reference for the balance control system. Therefore, adaptive changes occur to the vestibular system to affect control of body orientation with altered, or non-present, gravity and/or proprioceptive inputs. Upon return to a gravity environment, the vestibular system must re-incorporate the gravity vector and gravity-induced proprioceptive inputs into the balance control regime. The result is often a period of postural instability, which may also be associated with space motion sickness (oscillopsia, nausea, and vertigo). Previous studies by the JSC Neuroscience group have found that returning astronauts often employ alterations in gait mechanics to maintain postural control during gait. It is believed that these gait alterations are meant to decrease the transfer of heel strike shock energy to the head, thus limiting the contradictory head and eye movements that lead to gait instability and motion sickness symptoms. We analyzed pre- and post-spaceflight tri-axial accelerometer data from the NASA/MIR long duration spaceflight missions to assess the heel to head transfer of heel strike shock energy during locomotion. Up to seven gait sessions (three preflight, four postflight) of head and shank (lower leg) accelerometer data was previously collected from six astronauts who engaged in space flights of four to six months duration. In our analysis, the heel to head transmission of shock energy was compared using peak vertical acceleration (a), peak jerk (j) ratio, and relative kinetic energy (a). A host of generalized movement variables was produced

  17. Refrigerated cutting tools improve machining of superalloys

    NASA Technical Reports Server (NTRS)

    Dudley, G. M.

    1971-01-01

    Freon-12 applied to tool cutting edge evaporates quickly, leaves no residue, and permits higher cutting rate than with conventional coolants. This technique increases cutting rate on Rene-41 threefold and improves finish of machined surface.

  18. Laser cutting of energetic materials

    SciTech Connect

    Rivera, T.; Muenchausen, R.; Sanchez, J.

    1998-12-01

    The authors have demonstrated the feasibility of safely and efficiently cutting and drilling metal cases containing a variety of high explosives (HE) using a Nd:YAG laser. Spectral analysis of the optical emission, occurring during the laser-induced ablation process, is used to identify the removed material. By monitoring changes in the optical emission during the cutting process, the metal-He interface can be observed in real time and the cutting parameters adjusted accordingly. For cutting the HE material itself, the authors have demonstrated that this can be safely and efficiently accomplished by means of a ultraviolet (UV) laser beam obtained from the same Nd:YAG laser using the third or fourth harmonics. They are currently applying this technology to UXO identification and ordnance demilitarization.

  19. How Can I Stop Cutting?

    MedlinePlus

    ... Things to Help You Express the Pain and Deep Emotion Some people cut because the emotions that ... Privacy Policy & Terms of Use Visit the Nemours Web site. Note: All information on TeensHealth® is for ...

  20. Dealing with Cuts (For Parents)

    MedlinePlus

    ... For Kids For Parents MORE ON THIS TOPIC Cellulitis First Aid: Cuts Staph Infections Bites and Scratches ... Animal Bites Blood Childproofing and Preventing Household Accidents Cellulitis How Stitches Help Kids Heal The Story on ...

  1. Cutting thin sections of bone

    NASA Technical Reports Server (NTRS)

    Ashley, W. W.

    1972-01-01

    Medical equipment for obtaining repetitive planoparallel sections of bone to study healing of bone structure under high gravity stress is described. Device consists of modified saw with diamond cutting edges. Construction of device and manner of use are explained.

  2. Dealing with Cuts (For Parents)

    MedlinePlus

    ... daily. Call your doctor if the wound is red, swollen, tender, warm, or draining pus. For Bleeding From a Large or Deep Cut or Tear: Rinse off the wound with water so you can see it clearly and check ...

  3. Underwater welding, cutting and inspection

    SciTech Connect

    Tsai, C.L. . Ohio Underwater Welding Center)

    1995-02-01

    Underwater welding, cutting and inspection of offshore, inland waterway and port facilities are becoming a requirement for both military and industrial communities, as maintenance and repair costs continue to escalate, and as many of the facilities are in operation well beyond their intended design life. In nuclear applications, underwater welding, cutting and inspection for repair and modification of irradiated nuclear power plant components are also a requirement. This article summarizes recent developments in this emerging underwater technology.

  4. Microwave assisted hard rock cutting

    DOEpatents

    Lindroth, David P.; Morrell, Roger J.; Blair, James R.

    1991-01-01

    An apparatus for the sequential fracturing and cutting of subsurface volume of hard rock (102) in the strata (101) of a mining environment (100) by subjecting the volume of rock to a beam (25) of microwave energy to fracture the subsurface volume of rock by differential expansion; and , then bringing the cutting edge (52) of a piece of conventional mining machinery (50) into contact with the fractured rock (102).

  5. Interactive cutting path analysis programs

    NASA Technical Reports Server (NTRS)

    Weiner, J. M.; Williams, D. S.; Colley, S. R.

    1975-01-01

    The operation of numerically controlled machine tools is interactively simulated. Four programs were developed to graphically display the cutting paths for a Monarch lathe, Cintimatic mill, Strippit sheet metal punch, and the wiring path for a Standard wire wrap machine. These programs are run on a IMLAC PDS-ID graphic display system under the DOS-3 disk operating system. The cutting path analysis programs accept input via both paper tape and disk file.

  6. Concrete Cutting Refinement for Crater Repair

    DTIC Science & Technology

    2015-08-01

    47 Figure 37. CAT 375-7681 cutting-bit length versus saw-cut length...49 Figure 39. Worn Kennametal RP15 tooth on CAT SW45 after cutting in chert PCC........................... 50 Figure 40. Short Kennametal RP15...tooth on CAT SW45 after cutting in chert PCC. ......................... 50 Figure 41. Kennametal SM04 cutting-bit length versus saw-cut length

  7. Testing accelerometer rectification error caused by multidimensional composite inputs with double turntable centrifuge.

    PubMed

    Guan, W; Meng, X F; Dong, X M

    2014-12-01

    Rectification error is a critical characteristic of inertial accelerometers. Accelerometers working in operational situations are stimulated by composite inputs, including constant acceleration and vibration, from multiple directions. However, traditional methods for evaluating rectification error only use one-dimensional vibration. In this paper, a double turntable centrifuge (DTC) was utilized to produce the constant acceleration and vibration simultaneously and we tested the rectification error due to the composite accelerations. At first, we deduced the expression of the rectification error with the output of the DTC and a static model of the single-axis pendulous accelerometer under test. Theoretical investigation and analysis were carried out in accordance with the rectification error model. Then a detailed experimental procedure and testing results were described. We measured the rectification error with various constant accelerations at different frequencies and amplitudes of the vibration. The experimental results showed the distinguished characteristics of the rectification error caused by the composite accelerations. The linear relation between the constant acceleration and the rectification error was proved. The experimental procedure and results presented in this context can be referenced for the investigation of the characteristics of accelerometer with multiple inputs.

  8. Wearable Goniometer and Accelerometer Sensory Fusion for Knee Joint Angle Measurement in Daily Life

    PubMed Central

    Tognetti, Alessandro; Lorussi, Federico; Carbonaro, Nicola; de Rossi, Danilo

    2015-01-01

    Human motion analysis is crucial for a wide range of applications and disciplines. The development and validation of low cost and unobtrusive sensing systems for ambulatory motion detection is still an open issue. Inertial measurement systems and e-textile sensors are emerging as potential technologies for daily life situations. We developed and conducted a preliminary evaluation of an innovative sensing concept that combines e-textiles and tri-axial accelerometers for ambulatory human motion analysis. Our sensory fusion method is based on a Kalman filter technique and combines the outputs of textile electrogoniometers and accelerometers without making any assumptions regarding the initial accelerometer position and orientation. We used our technique to measure the flexion-extension angle of the knee in different motion tasks (monopodalic flexions and walking at different velocities). The estimation technique was benchmarked against a commercial measurement system based on inertial measurement units and performed reliably for all of the various tasks (mean and standard deviation of the root mean square error of 1.96 and 0.96∘, respectively). In addition, the method showed a notable improvement in angular estimation compared to the estimation derived by the textile goniometer and accelerometer considered separately. In future work, we will extend this method to more complex and multi-degree of freedom joints. PMID:26569249

  9. Wearable Goniometer and Accelerometer Sensory Fusion for Knee Joint Angle Measurement in Daily Life.

    PubMed

    Tognetti, Alessandro; Lorussi, Federico; Carbonaro, Nicola; de Rossi, Danilo

    2015-11-11

    Human motion analysis is crucial for a wide range of applications and disciplines. The development and validation of low cost and unobtrusive sensing systems for ambulatory motion detection is still an open issue. Inertial measurement systems and e-textile sensors are emerging as potential technologies for daily life situations. We developed and conducted a preliminary evaluation of an innovative sensing concept that combines e-textiles and tri-axial accelerometers for ambulatory human motion analysis. Our sensory fusion method is based on a Kalman filter technique and combines the outputs of textile electrogoniometers and accelerometers without making any assumptions regarding the initial accelerometer position and orientation. We used our technique to measure the flexion-extension angle of the knee in different motion tasks (monopodalic flexions and walking at different velocities). The estimation technique was benchmarked against a commercial measurement system based on inertial measurement units and performed reliably for all of the various tasks (mean and standard deviation of the root mean square error of 1:96 and 0:96, respectively). In addition, the method showed a notable improvement in angular estimation compared to the estimation derived by the textile goniometer and accelerometer considered separately. In future work, we will extend this method to more complex and multi-degree of freedom joints.

  10. Optimal methods of RTK-GPS/accelerometer integration to monitor the displacement of structures.

    PubMed

    Hwang, Jinsang; Yun, Hongsik; Park, Sun-Kyu; Lee, Dongha; Hong, Sungnam

    2012-01-01

    The accurate measurement of diverse displacements of structures is an important index for the evaluation of a structure's safety. In this study, a comparative analysis was conducted to determine the integrated RTK-GPS/accelerometer method that can provide the most precise structure displacement measurements. For this purpose, three methods of calculating the dynamic displacements from the acceleration data were comparatively analyzed. In addition, two methods of determining dynamic, static, and quasi-static displacements by integrating the displacements measured from the RTK-GPS system and the accelerometer were also comparatively analyzed. To ensure precise comparison results, a cantilever beam was manufactured onto which diverse types of displacements were generated to evaluate the measurement accuracy by method. Linear variable differential transformer (LVDT) measurements were used as references for the evaluation to ensure accuracy. The study results showed that the most suitable method of measuring the dynamic displacement with the accelerometer was to calculate the displacement by filtering and double-integrating the acceleration data using the FIR band-pass filter. The integration method that uses frequency-based displacement extraction was most appropriate for the integrated RTK-GPS/accelerometer method of comprehensively measuring the dynamic, static, and quasi-static displacements.

  11. Gestural Communication With Accelerometer-Based Input Devices and Tactile Displays

    DTIC Science & Technology

    2008-12-01

    Specifically, we look at embedding accelerometers into a soldier’s gloves and porting the gesture recognition and transmission systems to pocket-size...Carstens, C.B., Pettit , R., & White, T.L. (2006). Communicating through the use of vibrotactile displays for dismounted and mounted soldiers

  12. Microelectromechanical accelerometer with resonance-cancelling control circuit including an idle state

    DOEpatents

    Chu, Dahlon D.; Thelen, Jr., Donald C.; Campbell, David V.

    2001-01-01

    A digital feedback control circuit is disclosed for use in an accelerometer (e.g. a microelectromechanical accelerometer). The digital feedback control circuit, which periodically re-centers a proof mass in response to a sensed acceleration, is based on a sigma-delta (.SIGMA..DELTA.) configuration that includes a notch filter (e.g. a digital switched-capacitor filter) for rejecting signals due to mechanical resonances of the proof mass and further includes a comparator (e.g. a three-level comparator). The comparator generates one of three possible feedback states, with two of the feedback states acting to re-center the proof mass when that is needed, and with a third feedback state being an "idle" state which does not act to move the proof mass when no re-centering is needed. Additionally, the digital feedback control system includes an auto-zero trim capability for calibration of the accelerometer for accurate sensing of acceleration. The digital feedback control circuit can be fabricated using complementary metal-oxide semiconductor (CMOS) technology, bi-CMOS technology or bipolar technology and used in single- and dual-proof-mass accelerometers.

  13. Convergent Validity of Four Accelerometer Cutpoints with Direct Observation of Preschool Children's Outdoor Physical Activity

    ERIC Educational Resources Information Center

    Kahan, David; Nicaise, Virginie; Reuben, Karen

    2013-01-01

    Purpose: More than one fifth of American preschool-aged children are classified as overweight/obese. Increasing physical activity is one means of slowing/reversing progression to overweight or obesity. Measurement of physical activity in this age group relies heavily on motion sensors such as accelerometers. Output is typically interpreted through…

  14. A novel class of MEMS accelerometers for guidance and control of gun-fired munitions

    NASA Astrophysics Data System (ADS)

    Rastegar, Jahangir; Feng, Dake; Pereira, Carlos M.

    2015-05-01

    The state of art in shock resistant MEMS accelerometer design is to reduce the size of the proof-mass, thereby reducing the generated forces and moments due to shock loading. Physical stops are also provided to limit proof-mass motion to prevent damage to various moving components. The reduction of the proof-mass size reduces the sensor sensitivity. In addition, to increase the sensor dynamic response, proof-mass motion needs to be minimally damped, resulting in a significant sensor settling time after experiencing a high shock loading such as those experienced by gun-fired munitions during firing. The settling time is particularly important for accelerometers that are used in gun-fired munitions and mortars for navigation and guidance. This paper describes the development of a novel class of accelerometers that are provided with the means of locking the sensor proof-mass in its "null" position when subjected to acceleration levels above prescribed thresholds, thereby protecting the moving parts of the accelerometer. In munitions applications, the proof-mass is thereby locked in its null position during the firing and released during the flight to begin to measure flight acceleration with minimal settling time. Details of the design and operation of the developed sensors and results of their prototyping and testing are presented. The application of the developed technology to other types of inertial sensors and devices is discussed.

  15. IEEE802.15.6 -based multi-accelerometer WBAN system for monitoring Parkinson's disease.

    PubMed

    Keränen, Niina; Särestöniemi, Mariella; Partala, Juha; Hämäläinen, Matti; Reponen, Jarmo; Seppänen, Tapio; Iinatti, Jari; Jämsä, Timo

    2013-01-01

    In this paper we present a detailed example of a wireless body area network (WBAN) scenario utilizing the recent IEEE802.15.6 standard as applied to a multi-accelerometer system for monitoring Parkinson's disease and fall detection. Ultra wideband physical layer and standard security protocols are applied to meet application requirements for data rate and security.

  16. Comparison of Yamax pedometer and GT3X accelerometer steps in a free-living sample

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our objective was to compare steps detected by the Yamax pedometer (PEDO) versus the GT3X accelerometer (ACCEL) in free-living adults. Daily PEDO and ACCEL steps were collected from a sample of 23 overweight and obese participants (18 females; mean +/- sd: age = 52.6 +/- 8.4 yr.; body mass index = 3...

  17. New Validated Thresholds for Various Intensities of Physical Activity in Adolescents Using the Actigraph Accelerometer

    ERIC Educational Resources Information Center

    Vanhelst, Jeremy; Beghin, Laurent; Turck, Dominique; Gottrand, Frederic

    2011-01-01

    The aim of this study was to determine and validate the new thresholds for various intensities of physical activity in adolescents using the Actigraph accelerometer. Sixty healthy participants aged 10-16 years were recruited. Forty participants participated in the calibration study whereas the others participated in the validation study.…

  18. Using an inertial navigation algorithm and accelerometer to monitor chest compression depth during cardiopulmonary resuscitation.

    PubMed

    Boussen, Salah; Ibouanga-Kipoutou, Harold; Fournier, Nathalie; Raboutet, Yves Godio; Llari, Maxime; Bruder, Nicolas; Arnoux, Pierre Jean; Behr, Michel

    2016-09-01

    We present an original method using a low cost accelerometer and a Kalman-filter based algorithm to monitor cardiopulmonary resuscitation chest compressions (CC) depth. A three-axis accelerometer connected to a computer was used during CC. A Kalman filter was used to retrieve speed and position from acceleration data. We first tested the algorithm for its accuracy and stability on surrogate data. The device was implemented for CC performed on a manikin. Different accelerometer locations were tested. We used a classical inertial navigation algorithm to reconstruct CPR depth and frequency. The device was found accurate enough to monitor CPR depth and its stability was checked for half an hour without any drift. Average error on displacement was ±0.5mm. We showed that depth measurement was dependent on the device location on the patient or the rescuer. The accuracy and stability of this small low-cost accelerometer coupled to a Kalman-filter based algorithm to reconstruct CC depth and frequency, was found well adapted and could be easily implemented.

  19. Gravity Compensation Method for Combined Accelerometer and Gyro Sensors Used in Cardiac Motion Measurements.

    PubMed

    Krogh, Magnus Reinsfelt; Nghiem, Giang M; Halvorsen, Per Steinar; Elle, Ole Jakob; Grymyr, Ole-Johannes; Hoff, Lars; Remme, Espen W

    2017-01-23

    A miniaturized accelerometer fixed to the heart can be used for monitoring of cardiac function. However, an accelerometer cannot differentiate between acceleration caused by motion and acceleration due to gravity. The accuracy of motion measurements is therefore dependent on how well the gravity component can be estimated and filtered from the measured signal. In this study we propose a new method for estimating the gravity, based on strapdown inertial navigation, using a combined accelerometer and gyro. The gyro was used to estimate the orientation of the gravity field and thereby remove it. We compared this method with two previously proposed gravity filtering methods in three experimental models using: (1) in silico computer simulated heart motion; (2) robot mimicked heart motion; and (3) in vivo measured motion on the heart in an animal model. The new method correlated excellently with the reference (r (2) > 0.93) and had a deviation from reference peak systolic displacement (6.3 ± 3.9 mm) below 0.2 ± 0.5 mm for the robot experiment model. The new method performed significantly better than the two previously proposed methods (p < 0.001). The results show that the proposed method using gyro can measure cardiac motion with high accuracy and performs better than existing methods for filtering the gravity component from the accelerometer signal.

  20. Accelerometer tags: detecting and identifying activities in fish and the effect of sampling frequency.

    PubMed

    Broell, Franziska; Noda, Takuji; Wright, Serena; Domenici, Paolo; Steffensen, John Fleng; Auclair, Jean-Pierre; Taggart, Christopher T

    2013-04-01

    Monitoring and measuring the behaviour and movement of aquatic animals in the wild is typically challenging, though micro-accelerometer (archival or telemetry) tags now provide the means to remotely identify and quantify behavioural states and rates such as resting, swimming and migrating, and to estimate activity and energy budgets. Most studies use low-frequency (≤32 Hz) accelerometer sampling because of battery and data-archiving constraints. In this study we assessed the effect of sampling frequency (aliasing) on activity detection probability using the great sculpin (Myoxocephalus polyacanthoceaphalus) as a model species. Feeding strikes and escape responses (fast-start activities) and spontaneous movements among seven different great sculpin were triggered, observed and recorded using video records and a tri-axial accelerometer sampling at 100 Hz. We demonstrate that multiple parameters in the time and probability domains can statistically differentiate between activities with high detection (90%) and identification (80%) probabilities. Detection probability for feeding and escape activities decreased by 50% when sampling at <10 Hz. Our analyses illustrate additional problems associated with aliasing and how activity and energy-budget estimates can be compromised and misinterpreted. We recommend that high-frequency (>30 Hz) accelerometer sampling be used in similar laboratory and field studies. If battery and/or data storage is limited, we also recommend archiving the events via an on-board algorithm that determines the highest likelihood and subsequent archiving of the various event classes of interest.

  1. Optimal Methods of RTK-GPS/Accelerometer Integration to Monitor the Displacement of Structures

    PubMed Central

    Hwang, Jinsang; Yun, Hongsik; Park, Sun-Kyu; Lee, Dongha; Hong, Sungnam

    2012-01-01

    The accurate measurement of diverse displacements of structures is an important index for the evaluation of a structure’s safety. In this study, a comparative analysis was conducted to determine the integrated RTK-GPS/accelerometer method that can provide the most precise structure displacement measurements. For this purpose, three methods of calculating the dynamic displacements from the acceleration data were comparatively analyzed. In addition, two methods of determining dynamic, static, and quasi-static displacements by integrating the displacements measured from the RTK-GPS system and the accelerometer were also comparatively analyzed. To ensure precise comparison results, a cantilever beam was manufactured onto which diverse types of displacements were generated to evaluate the measurement accuracy by method. Linear variable differential transformer (LVDT) measurements were used as references for the evaluation to ensure accuracy. The study results showed that the most suitable method of measuring the dynamic displacement with the accelerometer was to calculate the displacement by filtering and double-integrating the acceleration data using the FIR band-pass filter. The integration method that uses frequency-based displacement extraction was most appropriate for the integrated RTK-GPS/accelerometer method of comprehensively measuring the dynamic, static, and quasi-static displacements. PMID:22368508

  2. The potential of micro-electro-mechanical accelerometers in human vibration measurements

    NASA Astrophysics Data System (ADS)

    Tarabini, Marco; Saggin, Bortolino; Scaccabarozzi, Diego; Moschioni, Giovanni

    2012-01-01

    This paper evaluates the advantages and the drawbacks deriving from the use of MEMS (micro-electro-mechanical systems) accelerometers for hand-arm and whole-body vibration measurements. Metrological performances of different transducers were assessed through the identification of their frequency response function, linearity, floor noise and sensitivity to thermal and electromagnetic disturbances. Experimental results highlighted a standard instrumental uncertainty (including the nonlinearity) lower than 5% with the single frequency calibration procedure, such a value was reduced to 2%. The temperature effect was negligible and the electromagnetic disturbances sensitivity was comparable to that of the piezoelectric accelerometers. The compatibility of measurements obtained with MEMS accelerometers with those of piezoelectric-based measurement chains was verified for two specific applications. An example of direct transducer fixation on the skin for vibration transmissibility measurements is also presented. Thanks to the MEMS peculiarities - mainly small sizes and low cost - since novel approaches in the vibration monitoring could be pursued. For instance, it is possible to include by design MEMS accelerometers in any hand-held tool at the operator interface, or inside the seats structures of cars, tractors and trucks. This could be a viable solution to easily obtain repeatable exposure measurements and could also provide diagnostic signals for the tools or seats of functional monitoring.

  3. Application of a tri-axial accelerometer to estimate jump frequency in volleyball.

    PubMed

    Jarning, Jon M; Mok, Kam-Ming; Hansen, Bjørge H; Bahr, Roald

    2015-03-01

    Patellar tendinopathy is prevalent among athletes, and most likely associated with a high jumping load. If methods for estimating jump frequency were available, this could potentially assist in understanding and preventing this condition. The objective of this study was to explore the possibility of using peak vertical acceleration (PVA) or peak resultant acceleration (PRA) measured by an accelerometer to estimate jump frequency. Twelve male elite volleyball players (22.5 ± 1.6 yrs) performed a training protocol consisting of seven typical motion patterns, including jumping and non-jumping movements. Accelerometer data from the trial were obtained using a tri-axial accelerometer. In addition, we collected video data from the trial. Jump-float serving and spike jumping could not be distinguished from non-jumping movements using differences in PVA or PRA. Furthermore, there were substantial inter-participant differences in both the PVA and the PRA within and across movement types (p < 0.05). These findings suggest that neither PVA nor PRA measured by a tri-axial accelerometer is an applicable method for estimating jump frequency in volleyball. A method for acquiring real-time estimates of jump frequency remains to be verified. However, there are several alternative approaches, and further investigations are needed.

  4. Identification of capacitive MEMS accelerometer structure parameters for human body dynamics measurements.

    PubMed

    Benevicius, Vincas; Ostasevicius, Vytautas; Gaidys, Rimvydas

    2013-08-22

    Due to their small size, low weight, low cost and low energy consumption, MEMS accelerometers have achieved great commercial success in recent decades. The aim of this research work is to identify a MEMS accelerometer structure for human body dynamics measurements. Photogrammetry was used in order to measure possible maximum accelerations of human body parts and the bandwidth of the digital acceleration signal. As the primary structure the capacitive accelerometer configuration is chosen in such a way that sensing part measures on all three axes as it is 3D accelerometer and sensitivity on each axis is equal. Hill climbing optimization was used to find the structure parameters. Proof-mass displacements were simulated for all the acceleration range that was given by the optimization problem constraints. The final model was constructed in Comsol Multiphysics. Eigenfrequencies were calculated and model's response was found, when vibration stand displacement data was fed into the model as the base excitation law. Model output comparison with experimental data was conducted for all excitation frequencies used during the experiments.

  5. Signals and Noises Acting On The Accelerometer Mounted In The Mpo (mercury Planetary Orbiter).

    NASA Astrophysics Data System (ADS)

    Iafolla, V.; Fiorenza, E.; Lucchesi, D.; Milyukov, V.; Nozzoli, S.

    The RadioScience experiments proposed for the BepiClombo ESA CORNERSTONE are aiming at performing planetary measurements such as: the rotation state of Mer- cury, the global structure of its gravity field and the local gravitational anomalies, but also to test some aspects of the General Relativity, to an unprecedented level of accu- racy. A high sensitivity accelerometer will measure the inertial acceleration acting on the MPO; these data, together with tracking data are used to evaluate the purely gravi- tational trajectory of the MPO, by transforming it to a virtual drag-free satellite system. At the Istituto di Fisica dello Spazio Interplanetario (IFSI) a high sensitive accelerom- eter named ISA (Italian Spring Accelerometer)* and considered for this mission has been studied. The main problems concerning the use of the accelerometer are related to the high dynamics necessary to follow the variation of the acceleration signals, with accuracy equal to 10^-9 g/sqr(Hz), and very high at the MPO orbital period and due to thermal noise introduced at the sidereal period of Mercury. The description of the accelerometer will be presented, with particular attention to the thermal problems and to the analysis regarding the choice of the mounting position on the MPO. *Project funded by the Italian Space Agency (ASI).

  6. Effect of Cut Quality on Hybrid Laser Arc Welding of Thick Section Steels

    NASA Astrophysics Data System (ADS)

    Farrokhi, F.; Nielsen, S. E.; Schmidt, R. H.; Pedersen, S. S.; Kristiansen, M.

    From an industrial point of view, in a laser cutting-welding production chain, it is of great importance to know the influence of the attainable laser cut quality on the subsequent hybrid laser arc welding process. Many studies have been carried out in the literature to obtain lower surface roughness values on the laser cut edge. However, in practice, the cost and reliability of the cutting process is crucial and it does not always comply with obtaining the highest surface quality. In this study, a number of experiments on 25 mm steel plates were carried out to evaluate the influence of cut surface quality on the final quality of the subsequent hybrid laser welded joints. The different cut surfaces were obtained by different industrial cutting methods including laser cutting, abrasive water cutting, plasma cutting, and milling. It was found that the mentioned cutting methods could be used as preparation processes for the subsequent hybrid laser arc welding. However, cut quality could determine the choice of process parameters of the following hybrid laser arc welding.

  7. Using wearable cameras to categorise type and context of accelerometer-identified episodes of physical activity

    PubMed Central

    2013-01-01

    Background Accelerometers can identify certain physical activity behaviours, but not the context in which they take place. This study investigates the feasibility of wearable cameras to objectively categorise the behaviour type and context of participants’ accelerometer-identified episodes of activity. Methods Adults were given an Actical hip-mounted accelerometer and a SenseCam wearable camera (worn via lanyard). The onboard clocks on both devices were time-synchronised. Participants engaged in free-living activities for 3 days. Actical data were cleaned and episodes of sedentary, lifestyle-light, lifestyle-moderate, and moderate-to-vigorous physical activity (MVPA) were identified. Actical episodes were categorised according to their social and environmental context and Physical Activity (PA) compendium category as identified from time-matched SenseCam images. Results There were 212 days considered from 49 participants from whom SenseCam images and associated Actical data were captured. Using SenseCam images, behaviour type and context attributes were annotated for 386 (out of 3017) randomly selected episodes (such as walking/transportation, social/not-social, domestic/leisure). Across the episodes, 12 categories that aligned with the PA Compendium were identified, and 114 subcategory types were identified. Nineteen percent of episodes could not have their behaviour type and context categorized; 59% were outdoors versus 39% indoors; 33% of episodes were recorded as leisure time activities, with 33% transport, 18% domestic, and 15% occupational. 33% of the randomly selected episodes contained direct social interaction and 22% were in social situations where the participant wasn’t involved in direct engagement. Conclusion Wearable camera images offer an objective method to capture a spectrum of activity behaviour types and context across 81% of accelerometer-identified episodes of activity. Wearable cameras represent the best objective method currently

  8. Respiratory signal derived from the smartphone built-in accelerometer during a Respiratory Load Protocol.

    PubMed

    Estrada, Luis; Torres, Abel; Sarlabous, Leonardo; Jané, Raimon

    2015-01-01

    The scope of our work focuses on investigating the potential use of the built-in accelerometer of the smartphones for the recording of the respiratory activity and deriving the respiratory rate. Five healthy subjects performed an inspiratory load protocol. The excursion of the right chest was recorded using the built-in triaxial accelerometer of a smartphone along the x, y and z axes and with an external uniaxial accelerometer. Simultaneously, the respiratory airflow and the inspiratory mouth pressure were recorded, as reference respiratory signals. The chest acceleration signal recorded in the z axis with the smartphone was denoised using a scheme based on the ensemble empirical mode decomposition, a noise data assisted method which decomposes nonstationary and nonlinear signals into intrinsic mode functions. To distinguish noisy oscillatory modes from the relevant modes we use the detrended fluctuation analysis. We reported a very strong correlation between the acceleration of the z axis of the smartphone and the reference accelerometer across the inspiratory load protocol (from 0.80 to 0.97). Furthermore, the evaluation of the respiratory rate showed a very strong correlation (0.98). A good agreement was observed between the respiratory rate estimated with the chest acceleration signal from the z axis of the smartphone and with the respiratory airflow signal: Bland-Altman limits of agreement between -1.44 and 1.46 breaths per minute with a mean bias of -0.01 breaths per minute. This preliminary study provides a valuable insight into the use of the smartphone and its built-in accelerometer for respiratory monitoring.

  9. Quasi-Real Time Estimation of Angular Kinematics Using Single-Axis Accelerometers

    PubMed Central

    Caroselli, Alessio; Bagalà, Fabio; Cappello, Angelo

    2013-01-01

    In human movement modeling, the problem of multi-link kinematics estimation by means of inertial measurement units has been investigated by several authors through efficient sensor fusion algorithms. In this perspective a single inertial measurement unit per link is required. This set-up is not cost-effective compared with a solution in which a single-axis accelerometer per link is used. In this paper, a novel fast technique is presented for the estimation of the sway angle in a multi-link chain by using a single-axis accelerometer per segment and by setting the boundary conditions through an ad hoc algorithm. The technique, based on the windowing of the accelerometer output, was firstly tested on a mechanical arm equipped with a single-axis accelerometer and a reference encoder. The technique is then tested on a subject performing a squat task for the knee flexion-extension angle evaluation by using two single-axis accelerometers placed on the thigh and shank segments, respectively. A stereo-photogrammetric system was used for validation. RMSEs (mean ± std) are 0.40 ± 0.02° (mean peak-to-peak range of 147.2 ± 4.9°) for the mechanical inverted pendulum and 1.01 ± 0.11° (mean peak-to-peak range of 59.29 ± 2.02°) for the knee flexion-extension angle. Results obtained in terms of RMSE were successfully compared with an Extended Kalman Filter applied to an inertial measurement unit. These results suggest the usability of the proposed algorithm in several fields, from automatic control to biomechanics, and open new opportunities to increase the accuracy of the existing tools for orientation evaluation. PMID:23322097

  10. Estimating Activity and Sedentary Behavior From an Accelerometer on the Hip or Wrist

    PubMed Central

    Rosenberger, Mary E.; Haskell, William L.; Albinali, Fahd; Mota, Selene; Nawyn, Jason; Intille, Stephen

    2013-01-01

    Previously the National Health and Examination Survey measured physical activity with an accelerometer worn on the hip for seven days, but recently changed the location of the monitor to the wrist. PURPOSE This study compared estimates of physical activity intensity and type with an accelerometer on the hip versus the wrist. METHODS Healthy adults (n=37) wore triaxial accelerometers (Wockets) on the hip and dominant wrist along with a portable metabolic unit to measure energy expenditure during 20 activities. Motion summary counts were created, then receiver operating characteristic (ROC) curves were used to determine sedentary and activity intensity thresholds. Ambulatory activities were separated from other activities using the coefficient of variation (CV) of the counts. Mixed model predictions were used to estimate activity intensity. RESULTS The ROC for determining sedentary behavior had greater sensitivity and specificity (71% and 96%) at the hip than the wrist (53% and 76%), as did the ROC for moderate to vigorous physical activity on the hip (70% and 83%) versus the wrist (30% and 69%). The ROC for the CV associated with ambulation had a larger AUC at the hip compared to the wrist (0.83 and 0.74). The prediction model for activity energy expenditure (AEE) resulted in an average difference of 0.55 (+/− 0.55) METs on the hip and 0.82 (+/− 0.93) METs on the wrist. CONCLUSIONS Methods frequently used for estimating AEE and identifying activity intensity thresholds from an accelerometer on the hip generally do better than similar data from an accelerometer on the wrist. Accurately identifying sedentary behavior from a lack of wrist motion presents significant challenges. PMID:23247702

  11. Cutting force predication based on integration of symmetric fuzzy number and finite element method.

    PubMed

    Wang, Zhanli; Hu, Yanjuan; Wang, Yao; Dong, Chao; Pang, Zaixiang

    2014-01-01

    In the process of turning, pointing at the uncertain phenomenon of cutting which is caused by the disturbance of random factors, for determining the uncertain scope of cutting force, the integrated symmetric fuzzy number and the finite element method (FEM) are used in the prediction of cutting force. The method used symmetric fuzzy number to establish fuzzy function between cutting force and three factors and obtained the uncertain interval of cutting force by linear programming. At the same time, the change curve of cutting force with time was directly simulated by using thermal-mechanical coupling FEM; also the nonuniform stress field and temperature distribution of workpiece, tool, and chip under the action of thermal-mechanical coupling were simulated. The experimental result shows that the method is effective for the uncertain prediction of cutting force.

  12. Cutting Force Predication Based on Integration of Symmetric Fuzzy Number and Finite Element Method

    PubMed Central

    Wang, Zhanli; Hu, Yanjuan; Wang, Yao; Dong, Chao; Pang, Zaixiang

    2014-01-01

    In the process of turning, pointing at the uncertain phenomenon of cutting which is caused by the disturbance of random factors, for determining the uncertain scope of cutting force, the integrated symmetric fuzzy number and the finite element method (FEM) are used in the prediction of cutting force. The method used symmetric fuzzy number to establish fuzzy function between cutting force and three factors and obtained the uncertain interval of cutting force by linear programming. At the same time, the change curve of cutting force with time was directly simulated by using thermal-mechanical coupling FEM; also the nonuniform stress field and temperature distribution of workpiece, tool, and chip under the action of thermal-mechanical coupling were simulated. The experimental result shows that the method is effective for the uncertain prediction of cutting force. PMID:24790556

  13. Surgical Cutting Simulation and Topology Refinement of Bio-Tissues and Bio-Object

    NASA Astrophysics Data System (ADS)

    Lin, Shiyong; Lee, Yuan-Shin; Narayan, Roger J.

    In this paper, we propose methodology and algorithms to generate realistic cuts on heterogeneous deformable object models. A three-dimensional node snapping algorithm is presented to modify the topology of deformable models, without adding new elements. Smooth cut is generated by duplicating and displacing mass points that have been snapped along the cutting path. Several sets of triangles representing different soft tissues are generated along the new cut to present the internal structures and material properties of heterogeneous deformable objects. A haptic device is integrated into cutting simulation system as a cutting tool. The proposed cutting techniques can be used in surgical simulation or other virtual simulations involving topological modification of heterogeneous soft materials to enhance the fidelity and realism.

  14. High Shock, High Frequency Characteristics of a Mechanical Isolator for a Piezoresistive Accelerometer, the ENDEVCO 7270AM6*

    SciTech Connect

    BATEMAN,VESTA I.; BROWN,FREDERICK A.; NUSSER,MICHAEL A.

    2000-07-01

    A mechanical isolator has been developed for a piezoresistive accelerometer. The purpose of the isolator is to mitigate high frequency shocks before they reach the accelerometer because the high frequency shocks may cause the accelerometer to resonate. Since the accelerometer is undamped, it often breaks when it resonates. The mechanical isolator was developed in response to impact test requirements for a variety of structures at Sandia National Laboratories (SNL). An Extended Technical Assistance Program (ETAP) with the accelerometer manufacturer has resulted in a commercial mechanically isolated accelerometer that is available to the general public, the ENDEVCO 7270AM6*, for three shock acceleration ranges of 6,000 g, 20,000 g, and 60,000 g. The in-axis response shown in this report has acceptable frequency domain performance from DC to 10 kHz and 10(XO)over a temperature range of {minus}65 F to +185 F. Comparisons with other isolated accelerometers show that the ENDEVCO 7270AM6 has ten times the bandwidth of any other commercial isolator. ENDEVCO 7270AM6 cross-axis response is shown in this report.

  15. Cut Front Geometry Characterization in Cutting Applications of Brass with Abrasive Water Jet

    NASA Astrophysics Data System (ADS)

    Akkurt, Adnan

    2010-06-01

    Abrasive water jet (AWJ) cutting is an advanced manufacturing process for machining hard to cut materials. In this study, brass-353 samples of different thicknesses were cut by AWJ using different feed rates to identify the relationships between depth of cut (material thickness), feed rate, and deflection of cutting edge geometry. The effects of material thickness on the AWJ cut surface roughness were investigated and discussed. Deflection of cutting edge geometry in AWJ cutting process was assessed. Cutting edge geometry was characterized by analyzing the surface properties of cut samples.

  16. A random forest classifier for the prediction of energy expenditure and type of physical activity from wrist and hip accelerometers.

    PubMed

    Ellis, Katherine; Kerr, Jacqueline; Godbole, Suneeta; Lanckriet, Gert; Wing, David; Marshall, Simon

    2014-11-01

    Wrist accelerometers are being used in population level surveillance of physical activity (PA) but more research is needed to evaluate their validity for correctly classifying types of PA behavior and predicting energy expenditure (EE). In this study we compare accelerometers worn on the wrist and hip, and the added value of heart rate (HR) data, for predicting PA type and EE using machine learning. Forty adults performed locomotion and household activities in a lab setting while wearing three ActiGraph GT3X+ accelerometers (left hip, right hip, non-dominant wrist) and a HR monitor (Polar RS400). Participants also wore a portable indirect calorimeter (COSMED K4b2), from which EE and metabolic equivalents (METs) were computed for each minute. We developed two predictive models: a random forest classifier to predict activity type and a random forest of regression trees to estimate METs. Predictions were evaluated using leave-one-user-out cross-validation. The hip accelerometer obtained an average accuracy of 92.3% in predicting four activity types (household, stairs, walking, running), while the wrist accelerometer obtained an average accuracy of 87.5%. Across all 8 activities combined (laundry, window washing, dusting, dishes, sweeping, stairs, walking, running), the hip and wrist accelerometers obtained average accuracies of 70.2% and 80.2% respectively. Predicting METs using the hip or wrist devices alone obtained root mean square errors (rMSE) of 1.09 and 1.00 METs per 6 min bout, respectively. Including HR data improved MET estimation, but did not significantly improve activity type classification. These results demonstrate the validity of random forest classification and regression forests for PA type and MET prediction using accelerometers. The wrist accelerometer proved more useful in predicting activities with significant arm movement, while the hip accelerometer was superior for predicting locomotion and estimating EE.

  17. A random forest classifier for the prediction of energy expenditure and type of physical activity from wrist and hip accelerometers

    PubMed Central

    Ellis, Katherine; Kerr, Jacqueline; Godbole, Suneeta; Lanckriet, Gert; Wing, David; Marshall, Simon

    2015-01-01

    Wrist accelerometers are being used in population level surveillance of physical activity (PA) but more research is needed to evaluate their validity for correctly classifying types of PA behavior and predicting energy expenditure (EE). In this study we compare accelerometers worn on the wrist and hip, and the added value of heart rate (HR) data, for predicting PA type and EE using machine learning. Forty adults performed locomotion and household activities in a lab setting while wearing three ActiGraph GT3X+ accelerometers (left hip, right hip, non-dominant wrist) and a HR monitor (Polar RS400). Participants also wore a portable indirect calorimeter (COSMED K4b2), from which EE and metabolic equivalents (METs) were computed for each minute. We developed two predictive models: a random forest classifier to predict activity type and a random forest of regression trees to estimate METs. Predictions were evaluated using leave-one-user-out cross-validation. The hip accelerometer obtained an average accuracy of 92.3% in predicting four activity types (household, stairs, walking, running), while the wrist accelerometer obtained an average accuracy of 87.5%. Across all 8 activities combined (laundry, window washing, dusting, dishes, sweeping, stairs, walking, running), the hip and wrist accelerometers obtained average accuracies of 70.2% and 80.2% respectively. Predicting METs using the hip or wrist devices alone obtained root mean square errors (rMSE) of 1.09 and 1.00 METs per 6-minute bout, respectively. Including HR data improved MET estimation, but did not significantly improve activity type classification. These results demonstrate the validity of random forest classification and regression forests for PA type and MET prediction using accelerometers. The wrist accelerometer proved more useful in predicting activities with significant arm movement, while the hip accelerometer was superior for predicting locomotion and estimating EE. PMID:25340969

  18. 9. MILE ROCK TUNNEL DURING EXCAVATION OF OPEN CUT PORTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. MILE ROCK TUNNEL DURING EXCAVATION OF OPEN CUT PORTION IN 1915. DEPARTMENT OF PUBLIC WORKS, MAP AND PLAN ROOM, PHOTO #2513. - Mile Rock Tunnel, Under Forty-eighth Avenue from Cabrillo Street to San Francisco Bay at Point Lobos, San Francisco, San Francisco County, CA

  19. 22. Photocopied August 1978. VIEW OF THE ROCK CUT, SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. Photocopied August 1978. VIEW OF THE ROCK CUT, SOUTH SIDE, JUNE 22, 1899, SHOWING SOME OF THE FLOODING WHICH PERIODICALLY DELAYED WORK HERE, AS WELL AS THE PROGRESS OF CONSTRUCTION (APPROXIMATELY 1/4 COMPLETED) TO THIS POINT. (32) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  20. Lifting the Lid on Disabled People against Cuts

    ERIC Educational Resources Information Center

    Williams-Findlay, Robert

    2011-01-01

    Against the backdrop of severe austerity measures sweeping across Europe, in this article I report upon the resurgence of activism among disabled people in the United Kingdom. My starting point is the creation of a new campaigning group called Disabled People Against Cuts (DPAC) formed by disabled people with and without a history of engagement…

  1. Evalaution and optimization of laser cutting parametersfor plywood materials

    NASA Astrophysics Data System (ADS)

    Eltawahni, H. A.; Rossini, N. S.; Dassisti, M.; Alrashed, K.; Aldaham, T. A.; Benyounis, K. Y.; Olabi, A. G.

    2013-09-01

    Laser process parameters influence greatly the width of kerfs and quality of the cut edges. This article reports experiments on the laser plywood-cutting performance of a CW 1.5 kW CO2 Rofin laser, based on design of experiments (DOE). The laser was used to cut three thicknesses 3, 6 and 9 mm of plywood panels. The process factors investigated are: laser power, cutting speed, air pressure and focal point position. The aim of this work is to relate the cutting edge quality parameters namely: upper kerf (UK), lower kerf (LK), the ratio between upper to lower kerfs and the operating cost to the process parameters mentioned above. Mathematical models were developed to establish the relationship between the process parameters and the edge quality parameters, and special graphs were drawn for this purpose. Finally, a numerical optimization was performed to find out the optimal process setting at which both kerfs would lead to a ratio of about 1, and at which low cutting cost take place.

  2. Tailor cutting of crystalline solar cells by laser micro jet

    NASA Astrophysics Data System (ADS)

    Bruckert, F.; Pilat, E.; Piron, P.; Torres, P.; Carron, B.; Richerzhagen, B.; Pirot, M.; Monna, R.

    2012-03-01

    Coupling a laser into a hair thin water micro jet (Laser Micro Jet, LMJ) for cutting applications offers a wide range of processes that are quite unique. As the laser beam is guided by internal reflections inside of a liquid cylinder, the cuts are naturally straight and do not reflect any divergence as otherwise occurs with an unguided laser beam. Furthermore, having a liquid media at the point of contact ensures a fast removal of heat and eventual debris ensuring clean cuts, which are free of any burrs. Many applications have indeed been developed for a large variety of materials, which are as different as e.g. diamond, silicon, aluminum, ceramic and hard metals. The photovoltaic industry has enjoyed in the last decades tremendous growth rates, which are still projected into the future. We focus here on the segment of Building Integrated PV (BIPV), which requests tailored solutions to actual buildings and not-one-fits-it-all standardized modules. Having the option to tailor cut solar cells opens a new field of BIPV applications. For the first time, finished crystalline solar cells have been LMJ cut into predetermined shapes. First results show that the cut is clean and neat. Preliminary solar performance measurements are positive. This opens a new avenue of tailored made modules instead of having to rely on the one-fits-alloy approach used so far.

  3. An Earthquake Shake Map Routine with Low Cost Accelerometers: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Alcik, H. A.; Tanircan, G.; Kaya, Y.

    2015-12-01

    Vast amounts of high quality strong motion data are indispensable inputs of the analyses in the field of geotechnical and earthquake engineering however, high cost of installation of the strong motion systems constitutes the biggest obstacle for worldwide dissemination. In recent years, MEMS based (micro-electro-mechanical systems) accelerometers have been used in seismological research-oriented studies as well as earthquake engineering oriented projects basically due to precision obtained in downsized instruments. In this research our primary goal is to ensure the usage of these low-cost instruments in the creation of shake-maps immediately after a strong earthquake. Second goal is to develop software that will automatically process the real-time data coming from the rapid response network and create shake-map. For those purposes, four MEMS sensors have been set up to deliver real-time data. Data transmission is done through 3G modems. A subroutine was coded in assembler language and embedded into the operating system of each instrument to create MiniSEED files with packages of 1-second instead of 512-byte packages.The Matlab-based software calculates the strong motion (SM) parameters at every second, and they are compared with the user-defined thresholds. A voting system embedded in the software captures the event if the total vote exceeds the threshold. The user interface of the software enables users to monitor the calculated SM parameters either in a table or in a graph (Figure 1). A small scale and affordable rapid response network is created using four MEMS sensors, and the functionality of the software has been tested and validated using shake table tests. The entire system is tested together with a reference sensor under real strong ground motion recordings as well as series of sine waves with varying amplitude and frequency. The successful realization of this software allowed us to set up a test network at Tekirdağ Province, the closest coastal point to

  4. The Nichols Wing Cutting Equipment

    NASA Technical Reports Server (NTRS)

    Ford, James B

    1923-01-01

    Described here is wing cutting equipment for the economical production of metal wings for wind tunnel models. The machine will make any size of constant-section wing or strut up to one-sixth inch chord by 36-inch span and up to a thickness of one and one-quarter inches. It cuts a smooth, true model that is accurate to within two-thousandths of an inch on any ordinate. The holding jaws are so designed as to leave the model free of chip marks, and the only hand finishing necessary after the cutting is a rub with amunite to remove burrs. The actual change on ordinate in this finishing rub is less than .0002 inches.

  5. Stresses in ultrasonically assisted bone cutting

    NASA Astrophysics Data System (ADS)

    Alam, K.; Mitrofanov, A. V.; Bäker, M.; Silberschmidt, V. V.

    2009-08-01

    Bone cutting is a frequently used procedure in the orthopaedic surgery. Modern cutting techniques, such as ultrasonic assisted drilling, enable surgeons to perform precision operations in facial and spinal surgeries. Advanced understanding of the mechanics of bone cutting assisted by ultrasonic vibration is required to minimise bone fractures and to optimise the technique performance. The paper presents results of finite element simulations on ultrasonic and conventional bone cutting analysing the effects of ultrasonic vibration on cutting forces and stress distribution. The developed model is used to study the effects of cutting and vibration parameters (e.g. amplitude and frequency) on the stress distributions in the cutting region.

  6. Electrostatic Accelerometer for the Gravity Recovery and Climate Experiment Follow-On Mission (GRACE FO)

    NASA Astrophysics Data System (ADS)

    Perrot, Eddy; Boulanger, Damien; Christophe, Bruno; Foulon, Bernard; Liorzou, Françoise; Lebat, Vincent

    2014-05-01

    The GRACE FO mission, led by the JPL (Jet Propulsion Laboratory), is an Earth-orbiting gravity mission, continuation of the GRACE mission, that will produce an accurate model of the Earth's gravity field variation providing global climatic data during five year at least. The mission involves two satellites in a loosely controlled tandem formation, with a micro-wave link, and optionally a laser link, measuring the inter-satellites distance variation. Non-uniformities in the distribution of the Earth's mass cause the distance between the two satellites to vary. This variation is measured to recover gravity, after subtracting the non-gravitational contributors, as the residual drag. ONERA (the French Aerospace Lab) is developing, manufacturing and testing electrostatic accelerometers measuring this residual drag applied on the satellites. The accelerometer is composed of two main parts: the Sensor Unit (including the Sensor Unit Mechanics - SUM - and the Front-End Electronic Unit - FEEU) and the Interface Control Unit. In the Accelerometer Core, located in the Sensor Unit Mechanics, the proof mass is levitated and maintained in a center of an electrode cage by electrostatic forces. Thus, any drag acceleration applied on the satellite involves a variation on the servo-controlled electrostatic suspension of the mass. The voltage on the electrodes providing this electrostatic force is the measurement output of the accelerometer. The Preliminary Design Review was achieved successfully on November 2013. The FEEU Engineering Model is under test. Preliminary results on electronic unit will be compared with the expected performance. The integration of the SUM Engineering Model and the first ground levitation of the proof-mass will be presented. The impact of the accelerometer defaults (geometry, electronic and parasitic forces) leads to bias, misalignment and scale factor error, non-linearity and noise. Some of these accelerometer defaults are characterized by tests with

  7. Document segmentation via oblique cuts

    NASA Astrophysics Data System (ADS)

    Svendsen, Jeremy; Branzan-Albu, Alexandra

    2013-01-01

    This paper presents a novel solution for the layout segmentation of graphical elements in Business Intelligence documents. We propose a generalization of the recursive X-Y cut algorithm, which allows for cutting along arbitrary oblique directions. An intermediate processing step consisting of line and solid region removal is also necessary due to presence of decorative elements. The output of the proposed segmentation is a hierarchical structure which allows for the identification of primitives in pie and bar charts. The algorithm was tested on a database composed of charts from business documents. Results are very promising.

  8. Hypervelocity cutting machine and method

    DOEpatents

    Powell, James R.; Reich, Morris

    1996-11-12

    A method and machine 14 are provided for cutting a workpiece 12 such as concrete. A gun barrel 16 is provided for repetitively loading projectiles 22 therein and is supplied with a pressurized propellant from a storage tank 28. A thermal storage tank 32,32A is disposed between the propellant storage tank 28 and the gun barrel 16 for repetitively receiving and heating propellant charges which are released in the gun barrel 16 for repetitively firing projectiles 22 therefrom toward the workpiece 12. In a preferred embodiment, hypervelocity of the projectiles 22 is obtained for cutting the concrete workpiece 12 by fracturing thereof.

  9. Hypervelocity cutting machine and method

    DOEpatents

    Powell, J.R.; Reich, M.

    1996-11-12

    A method and machine are provided for cutting a workpiece such as concrete. A gun barrel is provided for repetitively loading projectiles therein and is supplied with a pressurized propellant from a storage tank. A thermal storage tank is disposed between the propellant storage tank and the gun barrel for repetitively receiving and heating propellant charges which are released in the gun barrel for repetitively firing projectiles therefrom toward the workpiece. In a preferred embodiment, hypervelocity of the projectiles is obtained for cutting the concrete workpiece by fracturing thereof. 10 figs.

  10. Microbiopsy/precision cutting devices

    DOEpatents

    Krulevitch, Peter A.; Lee, Abraham P.; Northrup, M. Allen; Benett, William J.

    1999-01-01

    Devices for performing tissue biopsy on a small scale (microbiopsy). By reducing the size of the biopsy tool and removing only a small amount of tissue or other material in a minimally invasive manner, the risks, costs, injury and patient discomfort associated with traditional biopsy procedures can be reduced. By using micromachining and precision machining capabilities, it is possible to fabricate small biopsy/cutting devices from silicon. These devices can be used in one of four ways 1) intravascularly, 2) extravascularly, 3) by vessel puncture, and 4) externally. Additionally, the devices may be used in precision surgical cutting.

  11. Microbiopsy/precision cutting devices

    DOEpatents

    Krulevitch, P.A.; Lee, A.P.; Northrup, M.A.; Benett, W.J.

    1999-07-27

    Devices are disclosed for performing tissue biopsy on a small scale (microbiopsy). By reducing the size of the biopsy tool and removing only a small amount of tissue or other material in a minimally invasive manner, the risks, costs, injury and patient discomfort associated with traditional biopsy procedures can be reduced. By using micromachining and precision machining capabilities, it is possible to fabricate small biopsy/cutting devices from silicon. These devices can be used in one of four ways (1) intravascularly, (2) extravascularly, (3) by vessel puncture, and (4) externally. Additionally, the devices may be used in precision surgical cutting. 6 figs.

  12. Implementation of Steiner point of fuzzy set.

    PubMed

    Liang, Jiuzhen; Wang, Dejiang

    2014-01-01

    This paper deals with the implementation of Steiner point of fuzzy set. Some definitions and properties of Steiner point are investigated and extended to fuzzy set. This paper focuses on establishing efficient methods to compute Steiner point of fuzzy set. Two strategies of computing Steiner point of fuzzy set are proposed. One is called linear combination of Steiner points computed by a series of crisp α-cut sets of the fuzzy set. The other is an approximate method, which is trying to find the optimal α-cut set approaching the fuzzy set. Stability analysis of Steiner point of fuzzy set is also studied. Some experiments on image processing are given, in which the two methods are applied for implementing Steiner point of fuzzy image, and both strategies show their own advantages in computing Steiner point of fuzzy set.

  13. 49 CFR 234.237 - Reverse switch cut-out circuit.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Reverse switch cut-out circuit. 234.237 Section... Maintenance, Inspection, and Testing Maintenance Standards § 234.237 Reverse switch cut-out circuit. A switch, when equipped with a switch circuit controller connected to the point and interconnected with...

  14. 49 CFR 234.237 - Reverse switch cut-out circuit.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Reverse switch cut-out circuit. 234.237 Section... Maintenance, Inspection, and Testing Maintenance Standards § 234.237 Reverse switch cut-out circuit. A switch, when equipped with a switch circuit controller connected to the point and interconnected with...

  15. Shuttle high resolution accelerometer package experiment results - Atmospheric density measurements between 60-160 km

    NASA Technical Reports Server (NTRS)

    Blanchard, R. C.; Hinson, E. W.; Nicholson, J. Y.

    1988-01-01

    Indirect or inferred values of atmospheric density encountered by the Shuttle Orbiter during reentry have been calculated from acceleration measurements made by the High Resolution Accelerometer Package (HiRAP) and the Orbiter Inertial Measurement Unit (IMU) liner accelerometers. The atmospheric density data developed from this study represent a significant gain with respect to the body of data collected to date by various techniques in the altitude range of 60 to 160 km. The data are unique in that they cover a very wide horizontal range during each flight and provide insight into the actual density variations encountered along the reentry flight path. The data, which were collected over about 3 years, are also characterized by variations in solar activity, geomagnetic index, and local solar time. Comparison of the flight-derived densities with various atmospheric models have been made, and analyses have attempted to characterize the data and to show correlation with selected physical variables.

  16. Theoretical Analysis of an Optical Accelerometer Based on Resonant Optical Tunneling Effect

    PubMed Central

    Jian, Aoqun; Wei, Chongguang; Guo, Lifang; Hu, Jie; Tang, Jun; Liu, Jun; Zhang, Xuming; Sang, Shengbo

    2017-01-01

    Acceleration is a significant parameter for monitoring the status of a given objects. This paper presents a novel linear acceleration sensor that functions via a unique physical mechanism, the resonant optical tunneling effect (ROTE). The accelerometer consists of a fixed frame, two elastic cantilevers, and a major cylindrical mass comprised of a resonant cavity that is separated by two air tunneling gaps in the middle. The performance of the proposed sensor was analyzed with a simplified mathematical model, and simulated using finite element modeling. The simulation results showed that the optical Q factor and the sensitivity of the accelerometer reach up to 8.857 × 107 and 9 pm/g, respectively. The linear measurement range of the device is ±130 g. The work bandwidth obtained is located in 10–1500 Hz. The results of this study provide useful guidelines to improve measurement range and resolution of integrated optical acceleration sensors. PMID:28218642

  17. A piezoresistive micro-accelerometer with high frequency response and low transverse effect

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Zhao, Yulong; Tian, Bian; Liu, Yan; Wang, Zixi; Li, Cun; Zhao, You

    2017-01-01

    With the purpose of measuring vibration signals in high-speed machinery, this paper developed a piezoresistive micro-accelerometer with multi-beam structure by combining four tiny sensing beams with four suspension beams. The eight-beam (EB) structure was designed to improve the trade-off between the sensitivity and the natural frequency of piezoresistive accelerometer. Besides, the piezoresistor configuration in the sensing beams reduces the cross interference from the undesirable direction significantly. The natural frequency of the structure and the stress on the sensing beams are theoretically calculated, and then verified through finite element method (FEM). The proposed sensor is fabricated on the n-type single crystal silicon wafer and packaged for experiment. The results demonstrate that the developed device possesses a suitable characteristic in sensitivity, natural frequency and transverse effect, which allows its usage in the measuring high frequency vibration signals.

  18. Design and validation of a high-voltage levitation circuit for electrostatic accelerometers

    SciTech Connect

    Li, G.; Wu, S. C.; Zhou, Z. B.; Bai, Y. Z.; Hu, M.; Luo, J.

    2013-12-15

    A simple high-voltage circuit with a voltage range of 0 to 900 V and an open-loop bandwidth of 11 kHz is realized by using an operational amplifier and a MOSFET combination. The circuit is used for the levitation of a test mass of 71 g, suspended below the top-electrodes with a gap distance of 57 μm, so that the performance of an electrostatic accelerometer can be tested on the ground. The translation noise of the accelerometer, limited by seismic noise, is about 4 × 10{sup −8} m/s{sup 2}/Hz{sup 1/2} at 0.1 Hz, while the high-voltage coupling noise is one-order of magnitude lower.

  19. Purpose in life is associated with physical activity measured by accelerometer.

    PubMed

    Hooker, Stephanie A; Masters, Kevin S

    2016-06-01

    Previous research has shown that purpose in life, the belief that one's life is meaningful and goal-directed, is associated with greater engagement in self-reported physical activity. The purpose of this study was to examine the relationship between purpose in life and accelerometer-measured physical activity. Community volunteers (N = 104) completed measures of purpose in life and potential confounds and wore accelerometers for three consecutive days. Purpose in life was positively associated with objectively measured movement, moderate to vigorous physical activity, and with self-reported activity. These relationships were largely unchanged after controlling for potential confounds. These results suggest that purpose in life is a reliable correlate of physical activity.

  20. Gyro and accelerometer failure detection and identification in redundant sensor systems

    NASA Technical Reports Server (NTRS)

    Potter, J. E.; Deckert, J. C.

    1972-01-01

    Algorithms for failure detection and identification for redundant noncolinear arrays of single degree of freedom gyros and accelerometers are described. These algorithms are optimum in the sense that detection occurs as soon as it is no longer possible to account for the instrument outputs as the outputs of good instruments operating within their noise tolerances, and identification occurs as soon as it is true that only a particular instrument failure could account for the actual instrument outputs within the noise tolerance of good instruments. An estimation algorithm is described which minimizes the maximum possible estimation error magnitude for the given set of instrument outputs. Monte Carlo simulation results are presented for the application of the algorithms to an inertial reference unit consisting of six gyros and six accelerometers in two alternate configurations.