Journal articles on the topic 'Non-static calibration'
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Högström, R., J. Salminen, and M. Heinonen. "Calibration of hygrometers at non-static conditions." Measurement Science and Technology 31, no. 3 (December 20, 2019): 034003. http://dx.doi.org/10.1088/1361-6501/ab56a6.
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Kawalec, Małgorzata, Czerwińska Karolina, and Andrzej Pacana. "Influence of Technical Condition of Control and Measurement Equipment on Calibration Results." System Safety: Human - Technical Facility - Environment 3, no. 1 (May 1, 2021): 79–88. http://dx.doi.org/10.2478/czoto-2021-0009.
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Abstract In the paper there are analyzed the procedures used in the process of calibrating concerning control and measurement equipment. There was assumed the mathematical model of the measuring instrument which was then analyzed. The factors that result from the imperfect technical condition of the control and measurement equipment and may have an impact on the measurement results were also analyzed. Models of errors’ models were assumed that may affect the calibration results. The static calibration of control and measurement equipment was analyzed. The results of numerical simulations concerning the static calibration of control and measurement equipment were presented, taking into account the linear and non-linear processing functions of the measurement equipment. The results of computations obtained for various models of processing functions were compared with each other and conclusions were drawn regarding the accuracy of the mapping of the measured quantity.
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Wang Zongyang, 汪宗洋, 王斌 Wang Bin, 吴元昊 Wu Yuanhao, 孟浩然 Meng Haoran, 刘欣悦 Liu Xinyue, and 林旭东 Lin Xudong. "Calibration of Non-Common Path Static Aberrations by Using Phase Diversity Technology." Acta Optica Sinica 32, no. 7 (2012): 0701007. http://dx.doi.org/10.3788/aos201232.0701007.
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Ou, Jia, Tingfa Xu, Xiaochuan Gan, Xuejun He, Yan Li, Jiansu Qu, and Wei Zhang. "Research on a Dynamic Calibration Method for Photogrammetry Based on Rotary Motion." Applied Sciences 13, no. 5 (March 5, 2023): 3317. http://dx.doi.org/10.3390/app13053317.
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Photogrammetry as an engineering measurement technology for the rapid and non-contact acquisition of geometric parameters, such as the attitude, position, and shape of a measured object, is widely used in the development and production processes of the aerospace and automobile industries. The calibration of a corresponding photogrammetry system is the basis for ensuring the accuracy of photogrammetry. The dynamic and static calibration of existing photogrammetry systems has not yet established a system calibration specification or standard, and such calibration has mainly focused on the internal and external parameters of the camera used in a photogrammetry system. The calibration of static parameters cannot fully guarantee the dynamic performance of a photogrammetry system in the process of measuring dynamic targets or micro-deformations. Aiming at the problem of dynamic parameter calibration of photogrammetry systems, this paper proposes a dynamic calibration method based on a circular trajectory standard device, which can realize the calibration of parameters, such as dynamic length measurement error, and ensure an accurate evaluation of the dynamic measurement performance of photogrammetry systems.
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Wang, Shuang, Hua Zhang, and Guijin Wang. "OMC-SLIO: Online Multiple Calibrations Spinning LiDAR Inertial Odometry." Sensors 23, no. 1 (December 26, 2022): 248. http://dx.doi.org/10.3390/s23010248.
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Light detection and ranging (LiDAR) is often combined with an inertial measurement unit (IMU) to get the LiDAR inertial odometry (LIO) for robot localization and mapping. In order to apply LIO efficiently and non-specialistically, self-calibration LIO is a hot research topic in the related community. Spinning LiDAR (SLiDAR), which uses an additional rotating mechanism to spin a common LiDAR and scan the surrounding environment, achieves a large field of view (FoV) with low cost. Unlike common LiDAR, in addition to the calibration between the IMU and the LiDAR, the self-calibration odometer for SLiDAR must also consider the mechanism calibration between the rotating mechanism and the LiDAR. However, existing self-calibration LIO methods require the LiDAR to be rigidly attached to the IMU and do not take the mechanism calibration into account, which cannot be applied to the SLiDAR. In this paper, we propose firstly a novel self-calibration odometry scheme for SLiDAR, named the online multiple calibration inertial odometer (OMC-SLIO) method, which allows online estimation of multiple extrinsic parameters among the LiDAR, rotating mechanism and IMU, as well as the odometer state. Specially, considering that the rotating and static parts of the motor encoder inside the SLiDAR are rigidly connected to the LiDAR and IMU respectively, we formulate the calibration within the SLiDAR as two separate sets of calibrations: the mechanism calibration between the LiDAR and the rotating part of the motor encoder and the sensor calibration between the static part of the motor encoder and the IMU. Based on such a SLiDAR calibration formulation, we can construct a well-defined kinematic model from the LiDAR to the IMU with the angular information from the motor encoder. Based on the kinematic model, a two-stage motion compensation method is presented to eliminate the point cloud distortion resulting from LiDAR spinning and platform motion. Furthermore, the mechanism and sensor calibration as well as the odometer state are wrapped in a measurement model and estimated via an error-state iterative extended Kalman filter (ESIEKF). Experimental results show that our OMC-SLIO is effective and attains excellent performance.
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Toledo, Pedro, Paolo Crovetti, Hamilton Klimach, and Sergio Bampi. "Dynamic and Static Calibration of Ultra-Low-Voltage, Digital-Based Operational Transconductance Amplifiers." Electronics 9, no. 6 (June 12, 2020): 983. http://dx.doi.org/10.3390/electronics9060983.
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The calibration of the effects of process variations and device mismatch in Ultra Low Voltage (ULV) Digital-Based Operational Transconductance Amplifiers (DB-OTAs) is addressed in this paper. For this purpose, two dynamic calibration techniques, intended to dynamically vary the effective strength of critical gates by different modulation strategies, i.e., Digital Pulse Width Modulation (DPWM) and Dyadic Digital Pulse Modulation (DDPM), are explored and compared to classic static calibration. The effectiveness of the calibration approaches as a mean to recover acceptable performance in non-functional samples is verified by Monte-Carlo (MC) post-layout simulations performed on a 300 mV power supply, nW-power DB-OTA in 180 nm CMOS. Based on the same MC post-layout simulations, the impact of each calibration strategy on silicon area, power consumption, and OTA performance is discussed.
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Di Pasquo, Alessio, Enrico Monaco, Nicola Ghittori, Claudio Nani, and Luca Fanucci. "A Track-and-Hold Circuit with Tunable Non-Linearity and a Calibration Loop for PAM-8 SerDes Receivers." Electronics 11, no. 14 (July 13, 2022): 2199. http://dx.doi.org/10.3390/electronics11142199.
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In this brief, we propose a 60 GS/s high-linearity two-stage 8 × 8 time-interleaved track-and-hold circuit where it is possible to tune the static non-linearities of the second-stage buffer by applying a proper bias voltage. This allows us to maximize the static linearity of the buffer or introduce effects that counterbalance the non-linearities of other blocks of the analog front-end. To validate the proposed circuit, a prototype in TSMC 5 nm technology is designed and a linearity calibration loop is proposed for a Pulse Amplitude Modulation SerDes receiver. For the analog buffer, circuit-level simulations are performed in Cadence Virtuoso, while the calibration loop is simulated in MATLAB. The optimal bias voltage value can be found by modeling the track-and-hold linearity using a Taylor series and implementing the linearity calibration loop in MATLAB. By applying this result to the circuit-level simulation, we obtain a total harmonic distortion of over 50 dB, which matches with the maximum value achievable across the complete bias voltage control range. Lastly, the linearity of the system is also verified using a PAM-8 pseudorandom stream signal.
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Leguízamo, Alejandro, Seung C. Lee, Elizabeth L. Jeglic, and Cynthia Calkins. "Utility of the Static-99 and Static-99R With Latino Sex Offenders." Sexual Abuse 29, no. 8 (December 16, 2015): 765–85. http://dx.doi.org/10.1177/1079063215618377.
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The predictive validity of the Static-99 measures with ethnic minorities in the United States has only recently been assessed with mixed results. We assessed the predictive validity of the Static-99 and Static-99R with a sample of Latino sex offenders ( N = 483) as well as with two subsamples (U.S.-born, including Puerto Rico, and non-U.S.-born). The overall sexual recidivism rate was very low (1.9%). Both the Static-99 measures were able to predict sexual recidivism for offenders born in the United States and Puerto Rico, but neither was effective in doing so for other Latino immigrants. Calibration analyses ( N = 303) of the Static-99R were consistent with the literature and provided support for the potential use of the measure with Latinos born in the United States and Puerto Rico. These findings and their implications are discussed as they pertain to the assessment of Latino sex offenders.
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Gao, Chunfeng, Guo Wei, Lin Wang, Qi Wang, and Zhikun Liao. "A Systematic Calibration Modeling Method for Redundant INS with Multi-Sensors Non-Orthogonal Configuration." Micromachines 13, no. 10 (October 7, 2022): 1684. http://dx.doi.org/10.3390/mi13101684.
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Because of the non-orthogonal configuration of multi-sensors, the redundant inertial navigation system (INS) has a more complex error model compared with the traditional orthogonal INS, and the complexity of sensors configuration also increases the difficulty of error separation. Based on sufficient analysis of the error principle of redundant IMUs, a generalized high-accuracy calibration modeling method which is suitable for filtering method systematic calibration is summarized in this paper, and it has been applied to an RIMU prototype consisting of four ring laser gyros (RLGs) and four quartz accelerometers. Through the rotational excitation of the three-axis turntable in the laboratory, the high-precision filtering method systematic calibration of the RIMU is achieved, and static navigation and dynamic vehicle test experiments are also carried out. The experimental results reflect that the positioning accuracy can be obviously improved by using this new systematic calibration error model and the validity of this modeling method is also verified.
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K., Gobi, Kannapiran B., Devaraj D., and Valarmathi K. "Design, development and performance evaluation of pressure sensor using eddy current displacement sensing coil." Sensor Review 38, no. 2 (March 19, 2018): 248–58. http://dx.doi.org/10.1108/sr-07-2017-0145.
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Purpose The conventional strain gauge type pressure sensor suffers in static testing of engines due to the contact transduction method. This paper aims to focus on the concept of non-contact transduction-based pressure sensor using eddy current displacement sensing coil (ECDS) to overcome the temperature limitations of the strain gauge type pressure sensor. This paper includes the fabrication of prototypes of the proposed pressure sensor and its performance evaluation by static calibration. The fabricated pressure sensor is proposed to measure pressure in static test environment for a short period in the order of few seconds. The limitations of the fabricated pressure sensor related to temperature problems are highlighted and the suitable design changes are recommended to aid the future design. Design/methodology/approach The design of ECDS-based pressure sensor is aimed to provide non-contact transduction to overcome the limitations of the strain gauge type of pressure sensor. The ECDS is designed and fabricated with two configurations to measure deflection of the diaphragm corresponding to the applied pressure. The fabricated ECDS is calibrated using a standard micro meter to ensure transduction within limits. The fabricated prototypes of pressure sensors are calibrated using dead weight tester, and the calibration results are analyzed to select the best configuration. The proposed pressure sensor is tested at different temperatures, and the test results are analyzed to provide recommendations to overcome the shortcomings. Findings The performance of the different configurations of the pressure sensor using ECDS is evaluated using the calibration data. The analysis of the calibration results indicates that the pressure sensor using ECDS (coil-B) with the diaphragm as target is the best configuration. The accuracy of the fabricated pressure sensor with best configuration is ±2.8 per cent and the full scale (FS) output is 3.8 KHz. The designed non-contact transduction method extends the operating temperature of the pressure sensor up to 150°C with the specified accuracy for the short period. Originality/value Most studies of eddy current sensing coil focus on the displacement and position measurement but not on the pressure measurement. This paper is concerned with the design of the pressure sensor using ECDS to realize the non-contact transduction to overcome the limitations of strain gauge type pressure sensors and evaluation of the fabricated prototypes. It is shown that the accuracy of the proposed pressure sensor is not affected by the high temperature for the short period due to non-contact transduction using ECDS.
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Jovanovski, Andrew, and Brad Stappenbelt. "Measuring the Boxing Punch: Development and Calibration of a Non-Embedded In-Glove Piezo-Resistive Sensor." Proceedings 49, no. 1 (June 15, 2020): 13. http://dx.doi.org/10.3390/proceedings2020049013.
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Biomechanics measurement in boxing is becoming increasingly important for the analysis of boxing technique in order to promote exciting and safer boxing at both amateur and professional levels. Despite this interest, there have been few experiments within this field of research that have utilised a non-embedded in-glove sensor to measure the resultant power generated by a boxing punch. The aim of this study was to develop a dynamic measurement system, utilising a non-embedded in-glove sensor system. Two sensors were utilised; a tri-axial accelerometer to measure acceleration and a piezo-resistive force sensor hand wrap to measure the impact force of a boxer’s punch. The piezo-resistive system was calibrated using a static measurement system utilising simple load cells for force and laser displacement sensors for glove speed measurements. The system was tested on 31 novice boxing athletes participating in the study. A mean impact force of 2.31 kN ± 3.28 kN, an instantaneous velocity prior to impact of 4.73 m/s ± 0.35 m/s, an impact acceleration of 91 g ± 11 g, deceleration immediately following impact of 223 g ± 21 g and a maximum power dissipation of 11.2 kW ± 2.05 kW were measured. These values correspond well with prior studies using alternate measurement approaches. The calibration of the non-embedded in-glove piezo-resistive force sensor on the static measurement system yielded a correlation coefficient of 0.85.
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Tur, Andrei, Viktar Tur, Stanislav Derechennik, and Aliaksandr Lizahub. "An innovative safety format for structural system robustness checking." Budownictwo i Architektura 19, no. 4 (November 2, 2020): 067–84. http://dx.doi.org/10.35784/bud-arch.2133.
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The estimation of structural robustness remains one of the most important stages of the design of structural systems. Recommended design strategies for the robustness assessment are based on the provisions specified in the actual EN 1991-1-7 and ISO 2394:2015. Currently, the EN 1991-1-7 and ISO2394:2015 allows the use of indirect tie-force method, but normally, non-linear pseudo-static analysis is widely used, because it is based on more realistic constitutive relations for basic variables, which enables a simulation of the real structural behaviour. Implementation of the non-linear pseudo-static analysis for the assessment of a structural system in accidental design situations requires to adopt a different approach to safety format.
The paper presents an innovative approach to safety format calibration for non-linear analysis of RC-structures subjected to accidental loads. The proposed method of the robustness estimation is based on the joint energy-saving (conversion) approach and the full probabilistic method for the estimation of a safety format for pseudo-static non-linear response of modified (damaged) structural system. The proposed probabilistic considerations are based on the Order Statistic Theory.
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Johansen, Espen S., Othon K. Rediniotis, and Greg Jones. "The Compressible Calibration of Miniature Multi-Hole Probes." Journal of Fluids Engineering 123, no. 1 (September 6, 2000): 128–38. http://dx.doi.org/10.1115/1.1334377.
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This work presents the development of a data reduction algorithm for non-nulling, multihole pressure probes in compressible, subsonic flowfields. The algorithm is able to reduce data from any 5- or 7-hole probe and generate very accurate predictions of the velocity magnitude and direction, total and static pressures, Mach and Reynolds number and fluid properties like the density and viscosity. The algorithm utilizes a database of calibration data and a local least-squares interpolation technique. It has been tested on four novel miniature 7-hole probes that have been calibrated at NASA Langley Flow Modeling and Control Branch for the entire subsonic regime. Each of the probes had a conical tip with diameter of 1.65 mm. Excellent prediction capabilities are demonstrated with maximum errors in angle prediction less than 0.6 degrees and maximum errors in velocity prediction less than 1 percent, both with 99 percent confidence.
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Thürauf, Sabine, Oliver Hornung, Mario Körner, Florian Vogt, Alois Knoll, and M. Ali Nasseri. "Model-Based Calibration of a Robotic C-Arm System Using X-Ray Imaging." Journal of Medical Robotics Research 03, no. 03n04 (September 2018): 1841002. http://dx.doi.org/10.1142/s2424905x18410027.
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In interventional radiology or surgery, C-arm systems are typical imaging modalities. Apart from 2D X-ray images, C-arm systems are able to perform 2D/3D overlays. For this application, a previously recorded 3D volume is projected on a 2D X-ray image for providing additional information to the clinician. The required accuracy for this application is 1.5[Formula: see text]mm. Such a spatial accuracy is only achievable with C-arms, if a calibration is performed. State-of-the-art approaches interpolate between values of lookup tables of a sampled Cartesian volume. However, due to the non-linear system behavior in Cartesian space, a trade-off between the calibration effort and the calibrated volume is necessary. This leads to the calibration of the most relevant subvolume and high calibration times. We discuss a new model-based calibration approach for C-arm systems which potentially leads to a smaller calibration effort and simultaneously to an increased calibrated volume. In this work, we demonstrate that it is possible to calibrate a robotic C-arm system using X-ray images and that a static model of the system is required to achieve the desired accuracy for 2D/3D overlays, if re-orientations of the system are performed.
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Barnhart, Bradley L., Keith A. Sawicz, Darren L. Ficklin, and Gerald W. Whittaker. "MOESHA: A Genetic Algorithm for Automatic Calibration and Estimation of Parameter Uncertainty and Sensitivity of Hydrologic Models." Transactions of the ASABE 60, no. 4 (2017): 1259–69. http://dx.doi.org/10.13031/trans.12179.
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Abstract. Characterization of the uncertainty and sensitivity of model parameters is an essential facet of hydrologic modeling. This article introduces the multi-objective evolutionary sensitivity handling algorithm (MOESHA) that combines input parameter uncertainty and sensitivity analyses with a genetic algorithm calibration routine to dynamically sample the parameter space. This novel algorithm serves as an alternative to traditional static space-sampling methods, such as stratified sampling or Latin hypercube sampling. In addition to calibrating model parameters to a hydrologic model, MOESHA determines the optimal distribution of model parameters that maximizes model robustness and minimizes error, and the results provide an estimate for model uncertainty due to the uncertainty in model parameters. Subsequently, we compare the model parameter distributions to the distribution of a dummy variable (i.e., a variable that does not affect model output) to differentiate between impactful (i.e., sensitive) and non-impactful parameters. In this way, an optimally calibrated model is produced, and estimations of model uncertainty as well as the relative impact of model parameters on model output (i.e., sensitivity) are determined. A case study using a single-cell hydrologic model (EXP-HYDRO) is used to test the method using river discharge data from the Dee River catchment in Wales. We compare the results of MOESHA with Sobol’s global sensitivity analysis method and demonstrate that the algorithm is able to pinpoint non-impactful parameters, demonstrate the uncertainty of model results with respect to uncertainties in model parameters, and achieve excellent calibration results. A major drawback of the algorithm is that it is computationally expensive; therefore, parallelized methods should be used to reduce the computational burden. Keywords: Genetic algorithm, Hydrologic modeling, Model calibration, Sensitivity analysis, Uncertainty.
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Cui, Yun Xian, Bao Yuan Sun, W. Y. Ding, and F. D. Sun. "Development of Multilayer Composition Thin Film Thermocouple Cutting Temperature Sensor Based on Magnetron Sputtering." Advanced Materials Research 69-70 (May 2009): 515–19. http://dx.doi.org/10.4028/www.scientific.net/amr.69-70.515.
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In the paper, a new multilayer composition thin film thermocouple was developed, which can accurately measure the temperature nearby cutting edge in convenient and fast ways. By means of advanced Twinned microwave ECR plasma source enhanced Radio Frequency (RF) reaction non-balance magnetron sputtering technique, SiO2 insulating film, NiCr/NiSi sensor film and SiO2 protecting film were deposited on the surface HSS substrate. Both static calibration and dynamic calibration were completed. The results showed that the sensor had good performance, good linearity, quick dynamic response, response time constant was 12.7ms. The temperature near the cutting edge in cutting process of aluminum alloy was measured by the developed sensor. The bonding strength between multiple layer film and substrate of high-speed-steel met the presupposed demands.
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Heinssen, Sascha, Theodor Hillebrand, Maike Taddiken, Steffen Paul, and Dagmar Peters-Drolshagen. "On-Line Error Correction in Sensor Interface Circuits by Using Adaptive Filtering and Digital Calibration." Proceedings 2, no. 13 (November 30, 2018): 963. http://dx.doi.org/10.3390/proceedings2130963.
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Numerous non-ideal effects can distort the functionality of sensor interfaces and have to be considered during the design phase. In order to relax the requirements for the analog circuit components, adaptive filtering and digital calibration are used in this work to detect and correct different gain- and offset-errors. The error detection is performed by transmitting a test signal through the sensor interface continuously and in parallel to the sensor signal. In the digital domain, variations of the test signal are evaluated and present errors can be determined and eliminated. In this way, an on-line error correction is realized, which makes the sensor interface more robust against static and dynamic non-idealities. The proposed concept is demonstrated by correcting different gain- and offset-errors in a 65nm CMOS sensor interface.
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Khankalantary, Saeed, Saeed Ranjbaran, and Hassan Mohammadkhani. "Simultaneous compensation of systematic errors of a low-cost MEMS triaxial accelerometer and its temperature dependency without accurate laboratory equipment." Sensor Review 41, no. 2 (May 6, 2021): 208–15. http://dx.doi.org/10.1108/sr-12-2020-0309.
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Purpose Laboratory calibration methods are time-consuming and require accurate devices to find the error coefficients of the low-cost microelectromechanical system (MEMS) accelerometer. Besides, low-cost MEMS sensors highly depend on temperature because of their silicon property and the effect of temperature on error coefficients should also be considered for compensation. This paper aims to present a field calibration method in which the accelerometer is placed in different positions without any accurate equipment in a few minutes and its temperature is changed by a simple device like a hairdryer. Design/methodology/approach In this paper, a non-linear cost function is defined based on this rule that the magnitude of the acceleration measured by the accelerometer in static mode is equal to the gravity plus error factors. Also, the dependency of error coefficients of the accelerometer is presented as a second-order polynomial in this cost function. By minimizing the cost function, the accelerometer error coefficients include bias, scale factor and non-orthogonality and their temperature dependency are obtained simultaneously. Findings Simulation results in MATLAB and empirical results of a MPU6050 accelerometer verify the good performance of the proposed calibration method. Originality/value Finding a fast and simple field calibration method to calibrate a low-cost MEMS accelerometer and compensate for the temperature dependency without using accurate laboratory equipment can help a wide range of industries that use advanced and expensive sensors or use expensive laboratory equipment to calibrate their sensors, to decrease their costs.
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Lin, Sheng, Chun Wang, and Shi Jun Zhou. "Constraint Optimization of a Novel Flexure System with Two Rotation Freedom Degree." Applied Mechanics and Materials 268-270 (December 2012): 1304–7. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.1304.
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A two freedom flexure system is presented. All the constraints are selected in Case 2, type 1 and Case 2, type 2 in FACT chart. The locations of the non-redundant constraints are optimizated by change laws of the three order natural frequency with the position of constraint. All the redundant constraints are selected to increase the add symmetry to the flexure system. Results of Simulation of static calibration dominates that the flexure system is decoupled. The synthesis process of the two freedom flexure system proposes important reference for design of the flexure system.
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Upadhyay, Ganesh, Hifjur Raheman, and Rashmi Dubey. "Novel draught resistance sensing elements for measurement of drawbar power of agricultural machinery." Spanish Journal of Agricultural Research 20, no. 4 (October 3, 2022): e0208. http://dx.doi.org/10.5424/sjar/2022204-19171.
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Aim of study: To develop an instrumentation system comprising three force sensing elements to measure the draught resistance of any tillage and seeding tools during field operation by connecting one sensing element to each three-point linkage of the tractor.
Area of study: Department of AgFE, Indian Institute of Technology, Kharagpur, India
Material and methods: Commercial S-type transducers were packed laterally in between the curved plates perpendicular to the direction of travel in such a way that the magnitude of the imposed force decreased and its nature got reversed consequently during tillage force measurement. Finite element analysis was also performed on the proposed model of the sensing elements. The performance was evaluated on the basis of non-linearity, hysteresis, and non-repeatability. The data were validated with the draught values simultaneously recorded using instrumented three-point linkages of tractor.
Main results: It offered good sensitivity and linearity during static calibration. The measurement capacity based on maximum applied load during static calibration was 10 kN with accuracy 93.40%. The low values of mean percentage error (9.03%), maximum absolute variation (17.43%), and root mean square error (0.51 kN) revealed good accuracy of the system. Validation was conducted by comparing the data for an offset type disk harrow with the model outputs of previous studies to assess its suitability for other soil working conditions, and the results were satisfactory.
Research highlights: The advantages of this sensing device in the measurement of drawbar power are fewer changes in the hitching geometry, lower cost, and capability of quick hitching.
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Skaf, Nour, Olivier Guyon, Éric Gendron, Kyohoon Ahn, Arielle Bertrou-Cantou, Anthony Boccaletti, Jesse Cranney, et al. "On-sky validation of image-based adaptive optics wavefront sensor referencing." Astronomy & Astrophysics 659 (March 2022): A170. http://dx.doi.org/10.1051/0004-6361/202141514.
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Context. Differentiating between a true exoplanet signal and residual speckle noise is a key challenge in high-contrast imaging (HCI). Speckles result from a combination of fast, slow, and static wavefront aberrations introduced by atmospheric turbulence and instrument optics. While wavefront control techniques developed over the last decade have shown promise in minimizing fast atmospheric residuals, slow and static aberrations such as non-common path aberrations (NCPAs) remain a key limiting factor for exoplanet detection. NCPAs are not seen by the wavefront sensor (WFS) of the adaptive optics (AO) loop, hence the difficulty in correcting them. Aims. We propose to improve the identification and rejection of slow and static speckles in AO-corrected images. The algorithm known as the Direct Reinforcement Wavefront Heuristic Optimisation (DrWHO) performs a frequent compensation operation on static and quasi-static aberrations (including NCPAs) to boost image contrast. It is applicable to general-purpose AO systems as well as HCI systems. Methods. By changing the WFS reference at every iteration of the algorithm (a few tens of seconds), DrWHO changes the AO system point of convergence to lead it towards a compensation mechanism for the static and slow aberrations. References are calculated using an iterative lucky-imaging approach, where each iteration updates the WFS reference, ultimately favoring high-quality focal plane images. Results. We validated this concept through both numerical simulations and on-sky testing on the SCExAO instrument at the 8.2-m Subaru telescope. Simulations show a rapid convergence towards the correction of 82% of the NCPAs. On-sky tests were performed over a 10 min run in the visible (750 nm). We introduced a flux concentration (FC) metric to quantify the point spread function (PSF) quality and measure a 15.7% improvement compared to the pre-DrWHO image. Conclusions. The DrWHO algorithm is a robust focal-plane wavefront sensing calibration method that has been successfully demonstrated on-sky. It does not rely on a model and does not require wavefront sensor calibration or linearity. It is compatible with different wavefront control methods, and can be further optimized for speed and efficiency. The algorithm is ready to be incorporated in scientific observations, enabling better PSF quality and stability during observations.
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Krenk, Steen, and Jan Høgsberg. "Tuned resonant mass or inerter-based absorbers: unified calibration with quasi-dynamic flexibility and inertia correction." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2185 (January 2016): 20150718. http://dx.doi.org/10.1098/rspa.2015.0718.
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A common format is developed for a mass and an inerter-based resonant vibration absorber device, operating on the absolute motion and the relative motion at the location of the device, respectively. When using a resonant absorber a specific mode is targeted, but in the calibration of the device it may be important to include the effect of other non-resonant modes. The classic concept of a quasi-static correction term is here generalized to a quasi-dynamic correction with a background inertia term as well as a flexibility term. An explicit design procedure is developed, in which the background effects are included via a flexibility and an inertia coefficient, accounting for the effect of the non-resonant modes. The design procedure starts from a selected level of dynamic amplification and then determines the device parameters for an equivalent dynamic system, in which the background flexibility and inertia effects are introduced subsequently. The inclusion of background effect of the non-resonant modes leads to larger mass, stiffness and damping parameter of the device. Examples illustrate the relation between resonant absorbers based on a tuned mass or a tuned inerter element, and demonstrate the ability to attain balanced calibration of resonant absorbers also for higher modes.
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Himarosa, Rela Adi, and Suyitno Suyitno. "Design, Fabrication, and Testing of Prototype of Total Lumbar Disc Replacement." Journal of Energy, Mechanical, Material and Manufacturing Engineering 3, no. 1 (June 30, 2018): 1. http://dx.doi.org/10.22219/jemmme.v3i1.5618.
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Total Disc Replacement (TDR) implant is part of the prosthesis to treat degenerative disease by retaining the maneuverability of the disk itself. The TDR implant allows to repair the movement of the spines, absorbs the friction of intervertebral discs, and restore the height of the vertebrae. In this study, we constructed a new model of TDR implant, which is feasible to be mass-produced in Indonesia and performed static test to examine the mechanical properties of the new model. Before starting the prototype production, the finite element simulation is necessary. Simulation using Abaqus 6.14 software show that our design is safe from mechanical failure. The simulation test was performed using the static general model, non linear by considering the plasticity of UHMWPE material. Manufactured using CNC 3 Axis and the prototype was tested with ASTM 2077 standards, using two calibration model on horizontal position and tilted position of 27° to measure the compressive strength and shear strength respectively.
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Bordoy, Joan, Dominik Jan Schott, Jizhou Xie, Amir Bannoura, Philip Klein, Ludwig Striet, Fabian Hoeflinger, Ivo Haering, Leonhard Reindl, and Christian Schindelhauer. "Acoustic Indoor Localization Augmentation by Self-Calibration and Machine Learning." Sensors 20, no. 4 (February 20, 2020): 1177. http://dx.doi.org/10.3390/s20041177.
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An acoustic transmitter can be located by having multiple static microphones. These microphones are synchronized and measure the time differences of arrival (TDoA). Usually, the positions of the microphones are assumed to be known in advance. However, in practice, this means they have to be manually measured, which is a cumbersome job and is prone to errors. In this paper, we present two novel approaches which do not require manual measurement of the receiver positions. The first method uses an inertial measurement unit (IMU), in addition to the acoustic transmitter, to estimate the positions of the receivers. By using an IMU as an additional source of information, the non-convex optimizers are less likely to fall into local minima. Consequently, the success rate is increased and measurements with large errors have less influence on the final estimation. The second method we present in this paper consists of using machine learning to learn the TDoA signatures of certain regions of the localization area. By doing this, the target can be located without knowing where the microphones are and whether the received signals are in line-of-sight or not. We use an artificial neural network and random forest classification for this purpose.
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Vala, Jiří. "Existence and Convergence Questions in Computational Modelling of Crack Growth in Brittle and Quasi-Brittle Materials." Solid State Phenomena 258 (December 2016): 157–60. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.157.
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Computational modelling of the crack growth in brittle and quasi-brittle materials used in mechanical, civil, etc. engineering applies the cohesive zone model with various traction separation laws; determination of micro-mechanical parameters comes then from static tests, microscopic observation and numerical calibration. Although most authors refer to ill-possedness and need of artificial regularization in inverse problems (identification of material parameters), some difficulties originate even in nonlinear formulations of direct and sensitivity problems. This paper demonstrates the possibility of proper analysis of the existence of a weak solution and of the convergence of a corresponding numerical algorithm for such model problem, avoiding non-physical assumptions.
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Tazifor, Martial, Egon Zimmermann, Johan Alexander Huisman, Markus Dick, Achim Mester, and Stefan Van Waasen. "Model-Based Correction of Temperature-Dependent Measurement Errors in Frequency Domain Electromagnetic Induction (FDEMI) Systems." Sensors 22, no. 10 (May 20, 2022): 3882. http://dx.doi.org/10.3390/s22103882.
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Data measured using electromagnetic induction (EMI) systems are known to be susceptible to measurement influences associated with time-varying external ambient factors. Temperature variation is one of the most prominent factors causing drift in EMI data, leading to non-reproducible measurement results. Typical approaches to mitigate drift effects in EMI instruments rely on a temperature drift calibration, where the instrument is heated up to specific temperatures in a controlled environment and the observed drift is determined to derive a static thermal apparent electrical conductivity (ECa) drift correction. In this study, a novel correction method is presented that models the dynamic characteristics of drift using a low-pass filter (LPF) and uses it for correction. The method is developed and tested using a customized EMI device with an intercoil spacing of 1.2 m, optimized for low drift and equipped with ten temperature sensors that simultaneously measure the internal ambient temperature across the device. The device is used to perform outdoor calibration measurements over a period of 16 days for a wide range of temperatures. The measured temperature-dependent ECa drift of the system without corrections is approximately 2.27 mSm−1K−1, with a standard deviation (std) of only 30 μSm−1K−1 for a temperature variation of around 30 K. The use of the novel correction method reduces the overall root mean square error (RMSE) for all datasets from 15.7 mSm−1 to a value of only 0.48 mSm−1. In comparison, a method using a purely static characterization of drift could only reduce the error to an RMSE of 1.97 mSm−1. The results show that modeling the dynamic thermal characteristics of the drift helps to improve the accuracy by a factor of four compared to a purely static characterization. It is concluded that the modeling of the dynamic thermal characteristics of EMI systems is relevant for improved drift correction.
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Delmas, Antoine, Lamia Belguerras, Nicolas Weber, Freddy Odille, Cédric Pasquier, Jacques Felblinger, and Pierre-André Vuissoz. "Calibration and non-orthogonality correction of three-axis Hall sensors for the monitoring of MRI workers' exposure to static magnetic fields." Bioelectromagnetics 39, no. 2 (January 19, 2018): 108–19. http://dx.doi.org/10.1002/bem.22102.
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Hart, Michael L., Michael Drakopoulos, Christina Reinhard, and Thomas Connolley. "Complete elliptical ring geometry provides energy and instrument calibration for synchrotron-based two-dimensional X-ray diffraction." Journal of Applied Crystallography 46, no. 5 (September 18, 2013): 1249–60. http://dx.doi.org/10.1107/s0021889813022437.
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A complete calibration method to characterize a static planar two-dimensional detector for use in X-ray diffraction at an arbitrary wavelength is described. This method is based upon geometry describing the point of intersection between a cone's axis and its elliptical conic section. This point of intersection is neither the ellipse centre nor one of the ellipse focal points, but some other point which lies in between. The presented solution is closed form, algebraic and non-iterative in its application, and gives values for the X-ray beam energy, the sample-to-detector distance, the location of the beam centre on the detector surface and the detector tilt relative to the incident beam. Previous techniques have tended to require prior knowledge of either the X-ray beam energy or the sample-to-detector distance, whilst other techniques have been iterative. The new calibration procedure is performed by collecting diffraction data, in the form of diffraction rings from a powder standard, at known displacements of the detector along the beam path.
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Quintana-Rodríguez, J. A., J. F. Doyle, F. J. Carrión-Viramontes, Didier Samayoa-Ochoa, and J. Alfredo López-López. "Material Characterization for Dynamic Simulation of Non-Homogeneous Structural Members." Key Engineering Materials 449 (September 2010): 46–53. http://dx.doi.org/10.4028/www.scientific.net/kem.449.46.
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Generally, simulation of non-homogeneous materials requires a homogeneous representation with equivalent properties different from the constitutive elements. Determination of the equivalent properties for dynamic simulation is not always a direct and straightforward calculation, as they have to represent, not only the static reactions, but also the dynamic behavior, which depends on a more complex relation of the geometrical (area, inertia moment), mechanical (elastic modulus) and physical (density) properties. In this context, the Direct Sensitivity Method (DSM) is developed to calibrate structural parameters of a finite element model using a priori information with an inverse parameter identification scheme, where parameters are optimized through an error sensitivity function using experimental data with the dynamic responses of the model. Results demonstrate that parameters of materials can be calibrated efficiently from the DSM and that key aspects for this calibration are noise, sensitivity (structural and sensor), and the finite element model representation.
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Nouiraa, H., J. E. Deschaud, and F. Goulettea. "POINT CLOUD REFINEMENT WITH A TARGET-FREE INTRINSIC CALIBRATION OF A MOBILE MULTI-BEAM LIDAR SYSTEM." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 359–66. http://dx.doi.org/10.5194/isprs-archives-xli-b3-359-2016.
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LIDAR sensors are widely used in mobile mapping systems. The mobile mapping platforms allow to have fast acquisition in cities for example, which would take much longer with static mapping systems. The LIDAR sensors provide reliable and precise 3D information, which can be used in various applications: mapping of the environment; localization of objects; detection of changes. Also, with the recent developments, multi-beam LIDAR sensors have appeared, and are able to provide a high amount of data with a high level of detail. <br><br> A mono-beam LIDAR sensor mounted on a mobile platform will have an extrinsic calibration to be done, so the data acquired and registered in the sensor reference frame can be represented in the body reference frame, modeling the mobile system. For a multibeam LIDAR sensor, we can separate its calibration into two distinct parts: on one hand, we have an extrinsic calibration, in common with mono-beam LIDAR sensors, which gives the transformation between the sensor cartesian reference frame and the body reference frame. On the other hand, there is an intrinsic calibration, which gives the relations between the beams of the multi-beam sensor. This calibration depends on a model given by the constructor, but the model can be non optimal, which would bring errors and noise into the acquired point clouds. In the litterature, some optimizations of the calibration parameters are proposed, but need a specific routine or environment, which can be constraining and time-consuming. <br><br> In this article, we present an automatic method for improving the intrinsic calibration of a multi-beam LIDAR sensor, the Velodyne HDL-32E. The proposed approach does not need any calibration target, and only uses information from the acquired point clouds, which makes it simple and fast to use. Also, a corrected model for the Velodyne sensor is proposed. <br><br> An energy function which penalizes points far from local planar surfaces is used to optimize the different proposed parameters for the corrected model, and we are able to give a confidence value for the calibration parameters found. Optimization results on both synthetic and real data are presented.
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Falter, Jens, Marvin Stiefermann, Gernot Langewisch, Philipp Schurig, Hendrik Hölscher, Harald Fuchs, and André Schirmeisen. "Calibration of quartz tuning fork spring constants for non-contact atomic force microscopy: direct mechanical measurements and simulations." Beilstein Journal of Nanotechnology 5 (April 23, 2014): 507–16. http://dx.doi.org/10.3762/bjnano.5.59.
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Quartz tuning forks are being increasingly employed as sensors in non-contact atomic force microscopy especially in the “qPlus” design. In this study a new and easily applicable setup has been used to determine the static spring constant at several positions along the prong of the tuning fork. The results show a significant deviation from values calculated with the beam formula. In order to understand this discrepancy the complete sensor set-up has been digitally rebuilt and analyzed by using finite element method simulations. These simulations provide a detailed view of the strain/stress distribution inside the tuning fork. The simulations show quantitative agreement with the beam formula if the beam origin is shifted to the position of zero stress onset inside the tuning fork base and torsional effects are also included. We further found significant discrepancies between experimental calibration values and predictions from the shifted beam formula, which are related to a large variance in tip misalignment during the tuning fork assembling process.
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Meng, Xianchang, Yili Zheng, and Weiping Liu. "Development of Non-Destructive Testing Device for Plant Leaf Expansion Monitoring." Electronics 12, no. 1 (January 3, 2023): 249. http://dx.doi.org/10.3390/electronics12010249.
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This paper designs a plant leaf expansion pressure non-destructive detection device, aiming to promote plant leaf expansion pressure research and achieve precision irrigation. The design is based on leaf expansion pressure probe technology, which can effectively monitor the plant leaf expansion pressure by detecting the feedback of the leaf under constant pressure. In this paper, the stability of the sensor and the calibration model is tested. The calibration experiments showed that the coefficient of determination R2 of the sensor was over 0.99, the static test results showed that the range of the sensor was 0–300 kPa, and the fluctuation of the sensor was less than 0.2 kPa during the long-term stability test. The indoor comparison tests showed that there was a significant difference in the variation of leaf expansion pressure data between plants under drought conditions and normal conditions. The irrigation experiments showed that the leaf expansion pressure was very sensitive to irrigation. The correlation between the expansion pressure data and the environmental factors was analyzed. The correlation coefficient between expansion pressure and light intensity was found to be 0.817. The results of the outdoor experiments showed that there was a significant difference in the expansion pressure of plants under different weather conditions. The data show that the plant leaf expansion pressure non-destructive detection device designed in this paper can be used both as an effective means of detecting plant leaf expansion pressure and promoting the research of plant physiological feedback mechanisms and precision irrigation.
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Nouiraa, H., J. E. Deschaud, and F. Goulettea. "POINT CLOUD REFINEMENT WITH A TARGET-FREE INTRINSIC CALIBRATION OF A MOBILE MULTI-BEAM LIDAR SYSTEM." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 359–66. http://dx.doi.org/10.5194/isprsarchives-xli-b3-359-2016.
Full textAbstract:
LIDAR sensors are widely used in mobile mapping systems. The mobile mapping platforms allow to have fast acquisition in cities for example, which would take much longer with static mapping systems. The LIDAR sensors provide reliable and precise 3D information, which can be used in various applications: mapping of the environment; localization of objects; detection of changes. Also, with the recent developments, multi-beam LIDAR sensors have appeared, and are able to provide a high amount of data with a high level of detail. <br><br> A mono-beam LIDAR sensor mounted on a mobile platform will have an extrinsic calibration to be done, so the data acquired and registered in the sensor reference frame can be represented in the body reference frame, modeling the mobile system. For a multibeam LIDAR sensor, we can separate its calibration into two distinct parts: on one hand, we have an extrinsic calibration, in common with mono-beam LIDAR sensors, which gives the transformation between the sensor cartesian reference frame and the body reference frame. On the other hand, there is an intrinsic calibration, which gives the relations between the beams of the multi-beam sensor. This calibration depends on a model given by the constructor, but the model can be non optimal, which would bring errors and noise into the acquired point clouds. In the litterature, some optimizations of the calibration parameters are proposed, but need a specific routine or environment, which can be constraining and time-consuming. <br><br> In this article, we present an automatic method for improving the intrinsic calibration of a multi-beam LIDAR sensor, the Velodyne HDL-32E. The proposed approach does not need any calibration target, and only uses information from the acquired point clouds, which makes it simple and fast to use. Also, a corrected model for the Velodyne sensor is proposed. <br><br> An energy function which penalizes points far from local planar surfaces is used to optimize the different proposed parameters for the corrected model, and we are able to give a confidence value for the calibration parameters found. Optimization results on both synthetic and real data are presented.
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de Jesus, Karla, Luis Mourão, Hélio Roesler, Nuno Viriato, Kelly de Jesus, Mário Vaz, Ricardo Fernandes, and João Paulo Vilas-Boas. "3D Device for Forces in Swimming Starts and Turns." Applied Sciences 9, no. 17 (August 30, 2019): 3559. http://dx.doi.org/10.3390/app9173559.
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Biomechanical tools capable of detecting external forces in swimming starts and turns have been developed since 1970. This study described the development and validation of a three-dimensional (six-degrees of freedom) instrumented block for swimming starts and turns. Seven force plates, a starting block, an underwater structure, one pair of handgrips and feet supports for starts were firstly designed, numerically simulated, manufactured and validated according to the Fédération Internationale de Natation rules. Static and dynamic force plate simulations revealed deformations between 290 to 376 µε and 279 to 545 µε in the anterior-posterior and vertical axis and 182 to 328.6 Hz resonance frequencies. Force plates were instrumented with 24 strain gauges each connected to full Wheatstone bridge circuits. Static and dynamic calibration revealed linearity ( R 2 between 0.97 and 0.99) and non-meaningful cross-talk between orthogonal (1%) axes. Laboratory and ecological validation revealed the similarity between force curve profiles. The need for discriminating each upper and lower limb force responses has implied a final nine-force plates solution with seven above and two underwater platforms. The instrumented block has given an unprecedented contribution to accurate external force measurements in swimming starts and turns.
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Sueishi, Tomohiro, Ryota Nishizono, and Masatoshi Ishikawa. "EmnDash: A Robust High-Speed Spatial Tracking System Using a Vector-Graphics Laser Display with M-Sequence Dashed Markers." Journal of Robotics and Mechatronics 34, no. 5 (October 20, 2022): 1085–95. http://dx.doi.org/10.20965/jrm.2022.p1085.
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Camera-based wide-area self-posture estimation is an effective method to understand and learn about human motion, especially in sports. However, although rapid spatial tracking typically requires markers, prepositioned markers require extensive preparation in advance, and area projection markers exhibit problems in bright environments. In this study, we propose a system for spatial tracking and graphics display using vector-based laser projection embedded with M-sequence dashed line markers. The proposed approach is fast, wide-area, and can operate in bright environments. The system enables embedding and calibration of M-sequence codes in non-circular vector shapes, as well as rapid image processing recognition. We verified that the accuracy and speed of the proposed approach sufficed through static and dynamic tracking evaluations. We also demonstrate a practical application.
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Tsigeman, Elina, Sebastian Silas, Klaus Frieler, Maxim Likhanov, Rebecca Gelding, Yulia Kovas, and Daniel Müllensiefen. "The Jack and Jill Adaptive Working Memory Task: Construction, Calibration and Validation." PLOS ONE 17, no. 1 (January 27, 2022): e0262200. http://dx.doi.org/10.1371/journal.pone.0262200.
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Visuospatial working memory (VSWM) is essential to human cognitive abilities and is associated with important life outcomes such as academic performance. Recently, a number of reliable measures of VSWM have been developed to help understand psychological processes and for practical use in education. We sought to extend this work using Item Response Theory (IRT) and Computerised Adaptive Testing (CAT) frameworks to construct, calibrate and validate a new adaptive, computerised, and open-source VSWM test. We aimed to overcome the limitations of previous instruments and provide researchers with a valid and freely available VSWM measurement tool. The Jack and Jill (JaJ) VSWM task was constructed using explanatory item response modelling of data from a sample of the general adult population (Study 1, N = 244) in the UK and US. Subsequently, a static version of the task was tested for validity and reliability using a sample of adults from the UK and Australia (Study 2, N = 148) and a sample of Russian adolescents (Study 3, N = 263). Finally, the adaptive version of the JaJ task was implemented on the basis of the underlying IRT model and evaluated with another sample of Russian adolescents (Study 4, N = 239). JaJ showed sufficient internal consistency and concurrent validity as indicated by significant and substantial correlations with established measures of working memory, spatial ability, non-verbal intelligence, and academic achievement. The findings suggest that JaJ is an efficient and reliable measure of VSWM from adolescent to adult age.
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Chow, J. C. K., D. D. Lichti, K. D. Ang, K. Al-Durgham, G. Kuntze, G. Sharma, and J. Ronsky. "MODELLING ERRORS IN X-RAY FLUOROSCOPIC IMAGING SYSTEMS USING PHOTOGRAMMETRIC BUNDLE ADJUSTMENT WITH A DATA-DRIVEN SELF-CALIBRATION APPROACH." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-1 (September 26, 2018): 101–6. http://dx.doi.org/10.5194/isprs-archives-xlii-1-101-2018.
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<p><strong>Abstract.</strong> X-ray imaging is a fundamental tool of routine clinical diagnosis. Fluoroscopic imaging can further acquire X-ray images at video frame rates, thus enabling non-invasive in-vivo motion studies of joints, gastrointestinal tract, etc. For both the qualitative and quantitative analysis of static and dynamic X-ray images, the data should be free of systematic biases. Besides precise fabrication of hardware, software-based calibration solutions are commonly used for modelling the distortions. In this primary research study, a robust photogrammetric bundle adjustment was used to model the projective geometry of two fluoroscopic X-ray imaging systems. However, instead of relying on an expert photogrammetrist’s knowledge and judgement to decide on a parametric model for describing the systematic errors, a self-tuning data-driven approach is used to model the complex non-linear distortion profile of the sensors. Quality control from the experiment showed that 0.06<span class="thinspace"></span>mm to 0.09<span class="thinspace"></span>mm 3D reconstruction accuracy was achievable post-calibration using merely 15 X-ray images. As part of the bundle adjustment, the location of the virtual fluoroscopic system relative to the target field can also be spatially resected with an RMSE between 3.10<span class="thinspace"></span>mm and 3.31<span class="thinspace"></span>mm.</p>
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Nahkala, Brady A., Amy L. Kaleita, and Michelle L. Soupir. "Assessment of Input Parameters and Calibration Methods for Simulating Prairie Pothole Hydrology using AnnAGNPS." Applied Engineering in Agriculture 37, no. 3 (2021): 495–503. http://dx.doi.org/10.13031/aea.14399.
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HighlightsModel equifinality incurs user-driven decisions when modeling with AnnAGNPS.Prairie pothole models should be calibrated using a limited parameter search space.LiDAR-derived surface areas best represent prairie pothole hydrology in AnnAGNPS.Modeling field-scale prairie pothole spill-and-fill dynamics is currently limited.Abstract. The Annualized Agricultural Non-Point Source (AnnAGNPS) model was used to predict water volume in individual prairie potholes within the Des Moines Lobe of Iowa. AnnAGNPS can represent prairie potholes as static wetland areas located on preferential flow paths at field scale, whereas standard practice of watershed modeling is to fill depressions while preparing input data, and whereas models have lumped parameters at scales too large for individual pothole representation, or are considered too complex for widespread implementation. Here, we assess how key user inputs affect hydrologic calibration of 6 AnnAGNPS prairie pothole models, suggest methods for calibrating and modeling the impact of some potholes at field scale, and explain challenges in modeling prairie potholes with AnnAGNPS. Results indicate that user-defined pothole surface area does not significantly affect statistical calibration of the model. Nash-Sutcliffe Efficiency 0.26 to 0.79, R2 ranged from 0.37 to 0.80 and RSR ranged from 0.46 to 0.86. The area that best simulates pothole hydrology and expected physical parameters is derived from LiDAR and is considered the maximum extent of the pothole. Potholes were calibrated using a stepwise, iterative, limited search space method using multiple representations of their inundation extent. We graphically assessed statistical parameters to identify calibrated models and chose input parameters within reasonable ranges of published literature. This helped formulate our recommendation for the modeled pothole area. Finally, AnnAGNPS is limited in its ability to simulate field-scale pothole networks due to the placement of potholes within the model’s subbasin network. Investigating high-resolution subbasin delineation or more specific wetland placement may alleviate this issue. Keywords: AnnAGNPS, Farmed wetlands, Hydrology, Prairie potholes, Prairie pothole region.
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Rucki, Miroslaw. "Recent Development of Air Gauging in Industry 4.0 Context." Sensors 23, no. 4 (February 13, 2023): 2122. http://dx.doi.org/10.3390/s23042122.
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The paper presents a review of the research reports published in 2012–2022, dedicated to air gauging. Since most of the results are somehow related to Industry 4.0 concept, the review put the air gauging to the context of fourth industrial revolution. It was found that despite substantial decrease of the number of published papers in recent years, the investigations are still performed to improve air gauges, both in static and in non-steady states. Researchers paid attention to the digitization of the results, models and simulations, uncertainty estimation, calibration, and linearization. Specific applications covered real-time monitoring and in-process control, as well as form and surface topography measurements. Proposed solutions for integration with computer systems seem suitable for the air gauges be included to the sensor networks built according to the Industry 4.0 concept.
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Sánchez-Aparicio, Luis Javier, Mónica Herrero-Huerta, Rita Esposito, Hugo Roel Schipper, and Diego González-Aguilera. "Photogrammetric Solution for Analysis of Out-Of-Plane Movements of a Masonry Structure in a Large-Scale Laboratory Experiment." Remote Sensing 11, no. 16 (August 10, 2019): 1871. http://dx.doi.org/10.3390/rs11161871.
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This paper proposes a photogrammetric procedure able to determine out-of-plane movements experienced by a masonry structure subjected to a quasi-static cyclic test. The method tracks the movement of circular targets by means of a coarse-to-fine strategy. These targets were captured by means of a photogrammetric network, made up of four cameras optimized following the precepts of a zero-, first-, and second-order design. The centroid of each circular target was accurately detected for each image using the Hough transform, a sub-pixel edge detector based on the partial area effect, and a non-linear square optimization strategy. The three-dimensional (3D) coordinates of these targets were then computed through a photogrammetric bundle adjustment considering a self-calibration model of the camera. To validate the photogrammetric method, measurements were carried out in parallel to an ongoing test on a full-scale two-story unreinforced masonry structure (5.4 × 5.2 × 5.4-m) monitored with more than 200 contact sensors. The results provided by the contact sensors during one of the load phases were compared with those obtained by the proposed approach. According to this accuracy assessment, the method was able to determine the out-of-plane displacement during the quasi-static cyclic test with a sub-pixel accuracy of 0.58.
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Whig, Pawan, and Syed Naseem Ahmad. "A Novel Pseudo NMOS Integrated CC -ISFET Device for Water Quality Monitoring." Journal of Integrated Circuits and Systems 8, no. 2 (December 28, 2013): 98–103. http://dx.doi.org/10.29292/jics.v8i2.379.
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The paper presents a performance analysis of Novel CMOS Integrated Pseudo NMOS CC –ISFET (PNCC-ISFET) having zero static power dissipation. The main focus is on simulation of power and performance analysis along with the comparison with existing devices, which are used for water quality monitoring. This approach can improve calibration of device to a fairly wide range without the use of a high speed digital processor. The conventional devices generally used, consume high power and are not stable for long term monitoring. The conventional devices have a drawback of low value of slew rate, high power consumption, and non linear characteristics. In the proposed design(PNCC-ISFET) due to zero static power, low value of load capacitance on input signals, faster switching, use of fewer transistors and higher circuit density the device exhibits a better slew rate, piece-wise linear characteristic, and is seen consuming low power of the order of 30mW. The functionality of the circuit is tested using Tanner simulator version 15 for a 70nm CMOS process model. The proposed circuit reduces total power consumption per cycle, increases speed of operation, is fairly linear and simple to implement. This device has a simple architecture, and hence is very suitable for water quality monitoring applications.
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Dameto de España, Carmen, Gerhard Steiner, Harald Schuh, Constantinos Sioutas, and Regina Hitzenberger. "Versatile aerosol concentration enrichment system (VACES) operating as a cloud condensation nuclei (CCN) concentrator: development and laboratory characterization." Atmospheric Measurement Techniques 12, no. 9 (September 5, 2019): 4733–44. http://dx.doi.org/10.5194/amt-12-4733-2019.
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Abstract. The ability of atmospheric aerosol particles to act as cloud condensation nuclei (CCN) depends on many factors, including particle size, chemical composition and meteorological conditions. To expand our knowledge of CCN, it is essential to understand the factors leading to CCN activation. For this purpose, a versatile aerosol concentrator enrichment system (VACES) has been modified to select CCN at different supersaturations. The VACES enables sampling non-volatile CCN particles without altering their chemical and physical properties. The redesigned VACES enriches CCN particles by first passing the aerosol flow to a new saturator and then to a condenser. The activated particles are concentrated by an inertial virtual impactor and then can be returned to their original size by diffusion drying. For the calibration, the saturator temperature was fixed at 52 ∘C and the condenser temperature range was altered from 5 to 25 ∘C to obtain activation curves for NaCl particles of different sizes. Critical water vapour supersaturations can be calculated using the 50 % cut point of these curves. Calibration results have also shown that CCN concentrations can be enriched by a factor of approx. 17, which is in agreement with the experimentally determined enrichment factor of the original VACES. The advantage of the redesigned VACES over conventional CCN counters (both static and continuous flow instruments) lies in the substantial enrichment of activated CCN, which facilitates further chemical analysis.
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Wang, Jiawen, Jingqi Liang, Rui Wang, and Xiaobin Qi. "Dynamic Response Measurement of Elastic Structures Through Smart Digital Image Correlation Method and Calculation." Journal of Physics: Conference Series 2083, no. 4 (November 1, 2021): 042016. http://dx.doi.org/10.1088/1742-6596/2083/4/042016.
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Abstract Based on the proper improvement and development of the basic principle of digital image correlation method, a 3D-DIC measurement system is built. Its measurement principle and application process can be divided into four steps: camera calibration, image acquisition, image matching and three-dimensional reconstruction. The measurement system can realize non-contact and full-field measurement and has the advantages of not being affected by the test environment, not imposing additional mass on the test model, and high signal-to-noise ratio of the measured data. Taking the elastic plate model as an example, the accuracy and reliability of the measurement system in the measurement of static and dynamic displacement response are verified by using the measurement results of laser displacement meter as a reference. In addition, the tensile strain of the projectile aluminum alloy tail model and the ground mode of the elastic plate are tested to further verify the practicability of the test system.
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Zhang, Aibin, Zhaohui Wang, Quanjie Gao, Yiwei Fan, and Hongxia Wang. "Calibration and Validation of Flow Parameters of Irregular Gravel Particles Based on the Multi-Response Concept." Processes 11, no. 1 (January 13, 2023): 268. http://dx.doi.org/10.3390/pr11010268.
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The discrete element method (DEM) often uses the angle of repose to study the microscopic parameters of particles. This paper proposes a multi-objective optimization method combining realistic modeling of particles and image analysis to calibrate gravel parameters, after obtaining the actual static angle of repose (αAoR_S) and dynamic angle of repose (βAoR_D) of the particles by physical tests. The design variables were obtained by Latin hypercube sampling (LHS), and the radial basis function (RBF) surrogate model was used to establish the relationship between the objective function and the design variables. The optimized design of the non-dominated sorting genetic algorithm II (NSGA-II) with the actual angle of repose measurements was used to optimize the design to obtain the best combination of parameters. Finally, the parameter set was validated by a hollow cylinder test, and the relative error between the validation test and the optimized simulation results was only 3.26%. The validation result indicates that the method can be reliably applied to the calibration process of the flow parameters of irregular gravel particles. The development of solid–liquid two-phase flow and the wear behavior of centrifugal pumps were investigated using the parameter set. The results show that the increase in cumulative tangential contact forces inside the volute of centrifugal pumps makes it the component most likely to develop wear behavior. The results also illustrate the significant meaning of the accurate application of the discrete element method for improving the efficient production of industrial scenarios.
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Liu, Xin, Zheng Liu, Zhongwei Liang, Shun-Peng Zhu, José A. F. O. Correia, and Abílio M. P. De Jesus. "PSO-BP Neural Network-Based Strain Prediction of Wind Turbine Blades." Materials 12, no. 12 (June 12, 2019): 1889. http://dx.doi.org/10.3390/ma12121889.
Full textAbstract:
The full-scale static testing of wind turbine blades is an effective means to verify the accuracy and rationality of the blade design, and it is an indispensable part in the blade certification process. In the full-scale static experiments, the strain of the wind turbine blade is related to the applied loads, loading positions, stiffness, deflection, and other factors. At present, researches focus on the analysis of blade failure causes, blade load-bearing capacity, and parameter measurement methods in addition to the correlation analysis between the strain and the applied loads primarily. However, they neglect the loading positions and blade displacements. The correlation among the strain and applied loads, loading positions, displacements, etc. is nonlinear; besides that, the number of design variables is numerous, and thus the calculation and prediction of the blade strain are quite complicated and difficult using traditional numerical methods. Moreover, in full-scale static testing, the number of measuring points and strain gauges are limited, so the test data have insufficient significance to the calibration of the blade design. This paper has performed a study on the new strain prediction method by introducing intelligent algorithms. Back propagation neural network (BPNN) improved by Particle Swarm Optimization (PSO) has significant advantages in dealing with non-linear fitting and multi-input parameters. Models based on BPNN improved by PSO (PSO-BPNN) have better robustness and accuracy. Based on the advantages of the neural network in dealing with complex problems, a strain-predictive PSO-BPNN model for full-scale static experiment of a certain wind turbine blade was established. In addition, the strain values for the unmeasured points were predicted. The accuracy of the PSO-BPNN prediction model was verified by comparing with the BPNN model and the simulation test. Both the applicability and usability of strain-predictive neural network models were verified by comparing the prediction results with simulation outcomes. The comparison results show that PSO-BPNN can be utilized to predict the strain of unmeasured points of wind turbine blades during static testing, and this provides more data for characteristic structural parameters calculation.
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Scheiblhofer, Werner, Reinhard Feger, Andreas Haderer, and Andreas Stelzer. "Concept and realization of a low-cost multi-target simulator for CW and FMCW radar system calibration and testing." International Journal of Microwave and Wireless Technologies 10, no. 2 (February 13, 2018): 207–15. http://dx.doi.org/10.1017/s1759078718000028.
Full textAbstract:
AbstractWe present the realization of an frequency-modulated continuous-wave radar target simulator, based on a modulated-reflector radar system. The simulator, designed for the 24 GHz frequency band, uses low-cost modulated-reflector nodes and is capable to simultaneously generate multiple targets in a real-time environment. The realization is based on a modular approach and thus provides a high scalability of the whole system. It is demonstrated that the concept is able to simulate multiple artificial targets, located at user-selectable ranges and even velocities, utilized within a completely static setup. The characterization of the developed hardware shows that the proposed concept allows to dynamically and precisely adjust the radar cross-section of each single target within a dynamic range of 50 dB. Additionally, the provided range-proportional target frequency bandwidth makes the system perfectly suitable for fast and reliable intermediate frequency-chain calibration of multi-channel radar systems. Within this paper we demonstrate the application of the concept for a linear sweeped frequency-modulated continuous-wave radar. The presented approach is applicable to any microwave-based measurement system using frequency differences between transmit- and receive signals for range- and velocity evaluation, such as (non-)linear sweeped as well as pure Doppler radar systems.
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Formisano, Antonio, Hadi Monsef Ahmadi, and Federico M. Mazzolani. "Ductility and Behaviour Factor of RC Frame - Perforated SPSW Dual Systems." Key Engineering Materials 763 (February 2018): 835–45. http://dx.doi.org/10.4028/www.scientific.net/kem.763.835.
Full textAbstract:
In this paper the non-linear behaviour of dual seismic-resistant structures made of Reinforced Concrete Frames (RCF) and perforated Steel Plate Shear Walls (SPSWs) has been investigated. The starting point has been the numerical calibration by ABAQUS of an experimental test taken from literature on one-third scale three-storey RCF with infill SPSWs subjected to monotonically increasing horizontal loading. Based on results of the implemented FEM model, three types of perforated SPSWs with different percentages and position of holes have been numerically analysed through static non-linear analyses. On the basis of numerical results achieved, by comparing each other the values of shear strength, behaviour factor and ductility of the tested specimens, it has been observed a significant improvement of the ductile behaviour of the RCF equipped with perforated SPSWs with respect to the one obtained for the RCF provided with traditional solid SPSWs. In addition, the dual systems given by RCF and perforated SPSWs have provided a shear strength reduction of 26%, 46% and 51% in comparison to that of the original RCF - solid SPSW composite system, when holes percentage equal to 13%, 40% and 42% have been considered, respectively. Finally, it has been noticed that behaviour factors of perforated specimens have been increased with increasing adjoining distance among holes.
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Kachlakev, Damian I. "Horsetail Creek Bridge: Design Method Calibration and Experimental Results of Structural Strengthening with CFRP and GFRP Laminates." Advances in Structural Engineering 5, no. 2 (April 2002): 87–98. http://dx.doi.org/10.1260/1369433021502588.
Full textAbstract:
The Horsetail Creek Bridge, constructed in 1912, is located along the Historic Columbia River Highway in Oregon. In a recent rating of bridges, the cross beams of the structure were found to be 50 percent deficient in flexure and 94 percent deficient in shear, mainly due to the traffic loads increase. In order to identify suitable Fiber Reinforced Polymer strengthening system, few commercially available systems were reviewed and alternative designs were carried on. Concurrently, four full size beams were constructed to simulate the retrofit of the bridge. One served as a control, while the other three were reinforced with various configurations of FRP composites. Third point bending tests were conducted. Load, deflection and strain data were collected. Results revealed that addition of either GFRP or CFRP composites provided static capacity increase of 45 percent compared to the control beam. The beam strengthened with CFRP for flexure and GFRP for shear, which simulated the HCB cross beams after the retrofit, exhibited near 100 percent of moment capacity increase. The addition of GFRP for shear alone was sufficient to offset the lack of steel stirrups in the actual bridge, allowing for a conventionally reinforced concrete beam with significant shear deficiency to fail by yielding of the flexural failure. The resulting ultimate deflections of the shear GFRP reinforced beam were nearly twice those of the control shear deficient beam. A design method for flexure and shear was proposed before the onset of this experimental study and used on the HCB. The design procedure for flexure was refined to include provisions for non-crushing failure modes. It allowed for predicting the response of the beam at any applied moment.
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Hekič, Doron, Andrej Anžlin, Maja Kreslin, Aleš Žnidarič, and Peter Češarek. "Model Updating Concept Using Bridge Weigh-in-Motion Data." Sensors 23, no. 4 (February 12, 2023): 2067. http://dx.doi.org/10.3390/s23042067.
Full textAbstract:
Finite element (FE) model updating of bridges is based on the measured modal parameters and less frequently on the measured structural response under a known load. Until recently, the FE model updating did not consider strain measurements from sensors installed for weighing vehicles with bridge weigh-in-motion (B-WIM) systems. A 50-year-old multi-span concrete highway viaduct, renovated between 2017 and 2019, was equipped with continuous monitoring system with over 200 sensors, and a B-WIM system. In the most heavily instrumented span, the maximum measured longitudinal strains induced by the full-speed calibration vehicle passages were compared with the modelled strains. Based on the sensitivity study results, three variables that affected its overall stiffness were updated: Young’s modulus adjustment factor of all structural elements, and two anchorage reduction factors that considered the interaction between the superstructure and non-structural elements. The analysis confirmed the importance of the initial manual FE model updating to correctly reflect the non-structural elements during the automatic nonlinear optimisation. It also demonstrated a successful use of pseudo-static B-WIM loading data during the model updating process and the potential to extend the proposed approach to using random B-WIM-weighed vehicles for FE model updating and long-term monitoring of structural parameters and load-dependent phenomena.
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Erkomaishvili, David. "Alliance Index: Measuring Alignments in International Relations." International Studies 56, no. 1 (January 2019): 28–45. http://dx.doi.org/10.1177/0020881718825079.
Full textAbstract:
Orthodox approaches developed by Alliance Theory to study alliances are characterized by static and state-centric focus, which exposes theory’s logical limitations. In contrast, modern alignments are marked by continuous oscillations. Alignment stability—according to orthodox Alliance Theory—may be altogether misleading for the explanation of behaviour in alignment. This article theoretically re-conceptualizes the key notion of the orthodox Alliance Theory—the concept of alliance. Building on the basis of isolated but significant fragments of advanced research, the theoretical essence of the Alliance Theory is adjusted to encompass alignment process. Importantly, such a re-calibration bears in on an overlooked element common to all alignments—fluidity. Theoretical modification resulted in two important outcomes. First, the change of the vantage point in explaining alignments theoretically extends the orthodox Alliance Theory’s traditionally limited applicability, which excluded subnational and non-state actors. Second, the change allowed reviewing the essence of alignments focusing on a persistently evolving process, rather than on alignments’ institutional image. Sustained realignment, upgrading or downgrading of cooperative relations between actors and concurrent alignment to rival parties is no more confusing in explaining alignments. The article develops an alignment index and calculates it for the post-Soviet space.