Location Of Measurement Points Research Articles

Reconstruction and Analysis of Impact Forces on a Steel-Beam-Reinforced Concrete Deck

Impact forces applied to a steel-beam-reinforced concrete deck at various positions are reconstructed using an inverse algorithm based on dynamic signals captured using single-axis accelerometers. A deconvolution technique in the time domain utilising dynamic signals is adopted to reconstruct the impact force. Two deconvolution approaches are investigated, one with a transfer function in the convolution integral and the other without an explicit transfer function. The roles of the transfer function and regularisation are evaluated, addressing the efficiency of the methods and accuracy of reconstructed forces based on the coefficient of their correlation with the actual impact forces. The effects of some parameters on the accuracy of reconstructed impact force are studied, including the locations of impact and measurement points, the characteristics of reference impact force and the stiffness of impact hammer head.

Functional components for a design strategy: Hot cell shielding in the high reliability safeguards methodology

The high reliability safeguards (HRS) methodology has been established for the safeguardability of advanced nuclear energy systems (NESs). HRS is being developed in order to integrate safety, security, and safeguards concerns, while also optimizing these with operational goals for facilities that handle special nuclear material (SNM). Currently, a commercial pyroprocessing facility is used as an example system. One of the goals in the HRS methodology is to apply intrinsic features of the system to a design strategy. This current study investigates the thickness of the hot cell walls that could adequately shield processed materials. This is an important design consideration that carries implications regarding the formation of material balance areas, the location of key measurement points, and material flow in the facility.

Effect of positioning errors of frames on fuselage panel assembly deformation

In aircraft assembly, frames are usually used as the skeleton shape benchmarks of a fuselage panel to locate other parts accurately, thereby coordinating the relative position relationships between each part. In order to guarantee the assembly quality, a methodology for analyzing the effect of positioning errors of frames on fuselage panel assembly deformation is proposed. A finite element model of the fuselage panel is established first and then a mathematical model for representing the assembly deformation is derived. To contain more assembly deformation information, the optimal measurement point placement method is adopted to extract a set of finite element nodes as the measurement point locations from a large candidate set. Meanwhile, the mathematical relationship between the position errors of measurement points and the positioning errors of frames is also determined, which is then combined with the Monte Carlo simulation and the grey relational analysis to quantitatively analyze the impacts of the positioning error(s) generated by single or multiple frames on fuselage panel assembly deformation.

Study of the locations of measurement points on the greater trochanter for the measurement of trochanter-malleolar distance by physical therapists

Study of the locations of measurement points on the greater trochanter for the measurement of trochanter-malleolar distance by physical therapists

TU-F-12A-08: Verification of APBI Balloon Integrity Using Ultrasound Imaging

Purpose: An overview of the ultrasound imaging artifacts encountered in Mammosite balloon APBI is presented. The goal was to determine whether clinically relevant changes in balloon size resulting from leakage can be detected by ultrasound imaging and also to compare the magnitude of size variations using both ultrasound and CT imaging. Methods: Ultrasound imaging of a Mammosite balloon phantom was performed to better understand measurement errors and accuracy. The dose to the prescription point as a function of balloon diameter was computed for different sized balloons. The results were compared to phantom measurements of balloon diameter versus filling volume to assess the dose change that would result from tissue moving inward with a shrinking balloon boundary. In APBI patients undergoing a course of 10 treatment fractions, an assessment was made of the variability and accuracy of balloon size measured with ultrasound imaging compared to CT. Results: Ultrasound artifacts combine to form a false image of the distal balloon boundary. Proper US probe orientation and choice of measurement point locations improves distance measurement accuracy. A 1 mm change in balloon diameter is measurable with ±0.1 mm error; this 1 mm change corresponding to <4% change in dose at a distance 1 cm from the balloon. In patients, the implanted balloon diameters ranged from 3.4 to 5.8 cm. Measurement errors relative to CT averaged less than 1.4 mm and variability (standard deviation) over the course of treatment averaged 1.9 mm. Conclusion: Complex and misleading image artifacts can be minimized by proper probe orientation, and accurate balloon diameter measurement requires consistent image analysis methods. Ultrasound imaging can detect dosimetrically relevant changes in the size of a leaking Mammosite balloon, therefore ultrasound imaging can be used for verification of balloon integrity over the course of APBI treatment.

An Exploration into Measurement Consistency on Coordinate Measuring Machines

In high precision industry, the measurement of geometry is often performed using coordinate measuring machines (CMMs). Measurements on CMMs can occur at many places within a long and global supply chain. In this context it is a challenge to control consistency, so that measurements are applied with appropriate levels of rigour and achieve comparable results, wherever and whenever they are performed. In this paper, a framework is outlined in which consistency is controlled through measurement strategy, such as the number and location of measurement points. The framework is put to action in a case study, demonstrating the usefulness of the approach and highlighting the dangers of imposing rigid measurement strategies across the supply chain, even if linked to standardised manufacturing processes. Potential mitigations, and the requirements for future research, are outlined.

Study on the number and location of measurement points for an MFD perimeter control scheme: a case study of Zurich

The goal of this paper is to evaluate the data requirements for a possible implementation of a macroscopic fundamental diagram (MFD) control scheme in an urban area. Particularly, we have studied the accuracy of MFDs created using only a percentage of the links (i.e., streets). This is especially useful because monitoring resources are often scarce, and most cities do not have access to the large amount of information that is typically associated with the construction of an MFD. We evaluated several strategies that cities typically use to place fixed monitoring devices (e.g., loop detectors), and compared them with a quasi-optimal way to choose the links. The results show that independently of the strategy used for link selection, a minimum of 25 % of network coverage, according to our accuracy methodology, ensures an average error in density ratios below 15 percentage points (ppts). Based on the particular case of the city of Zurich, we also analyzed the feasibility of implementing an MFD control scheme with the links that are currently monitored. Results are very encouraging, showing an average error below 9 ppts. Although all results were obtained with a VISSIM microsimulation model of the inner city of Zurich, we believe the knowledge and methodology presented here can be transferred to other urban areas. In fact, we are hopeful that this research can contribute to making the implementation of an MFD control scheme feasible for many cities.

Key characteristics-based sensor distribution in multi-station assembly processes

This paper presents a novel approach for optimal key characteristics-based sensor distribution in a multi-station assembly process, for the purpose of diagnosing variation sources responsible for product quality defects in a timely manner. Current approaches for sensor distribution are based on the assumption that measurement points can be allocated at arbitrary locations on the part or subassembly. This not only presents challenges in the implementation of these approaches but additionally does not allow required product assurance and quality control standards to be integrated with them, due to lack of explicit relations between measured features and geometric dimensioning and tolerancing (GD&T). Furthermore, it causes difficulty in calibration of measurement system and increases the likelihood of measurement error due to the introduction of measurement points not defined in GD&T. In the proposed approach, we develop methodology for optimal sensor allocation for 6-sigma root cause analysis that maximizes the number of measurement points placed at critical design features called Key Characteristics (KCs) which are classified into: Key Product Characteristics and Key Control Characteristics and represent critical product and process design features, respectively. In particular, KCs have defined dimensional and geometric tolerances which provides necessary design reference model for process control and diagnosis of product 6-sigma variation faults. The proposed approach allows obtaining minimum required production system 6-sigma diagnosability. A feature-based procedure is proposed which includes Genetic Algorithm-based approach (allowing pre-defined KCs as the measurement points) and state-of-the-art approaches (unrestricted location of measurement points) to iteratively include arbitrary measurement points together with KCs in the final sensor layout. A case study of automotive assembly processes is used to illustrate the proposed feature-based approach.

Influence of Friction Stir Welding on Hardness Distribution in Joints of AlZn5Mg1 Alloy

The article presents the research results of hardness values distribution of friction stir welded joint (FSW) alloy AW 7020 (AlZn5Mg1). FSW is a method of welding in the solid state, mechanical properties of joints welded by that method can be higher than that for arc welding techniques (MIG, TIG). The parameters of friction stir welding (FSW) used to join 7020 alloy were presented. Metallographic analysis showed the correctly structured FSW welded 7020 alloy. The study was carried out using Vickers hardness HV5 in accordance with the requirements of the Polish Standard PN-EN 6507 using a hardness testing machine HPO-10. The location of measurement points in the butt joint was determined in accordance with PN-EN 1043-1:2000. The indenter load was 49 N. In order to determine the effect of bonding method on structure change of the material microscopic examination was performed using an optical microscope ZEISS Axiovert 25.The test specimens were polished and then etched with KELLER reagent. This enabled the precise identification of zones present in the joint, such as: weld nugget, thermo-mechanically affected zone, native material. To determine the grain size in the different zones of joints bonded by FSW AxioVision 4.8.2 software was used. Hardness testing in across researched joints showed that the highest value of hardness is in the weld and the lowest is in the native material.

A numerical method for solving an inverse thermoacoustic problem

In this paper, we consider an inverse problem of determining the initial condition of an initial boundary value problem for the wave equation with some additional information about solving a direct initial boundary value problem. The information is obtained from measurements at the boundary of the solution domain. The purpose of our paper is to construct a numerical algorithm for solving the inverse problem by an iterative method called a method of simple iteration (MSI) and to study the resolution quality of the inverse problem as a function of the number and location of measurement points. Three two-dimensional inverse problem formulations are considered. The results of our numerical calculations are presented. It is shown that the MSI decreases the objective functional at each iteration step. However, due to the ill-posedness of the inverse problem the difference between the exact and approximate solutions decreases up to some fixed number kmin, and then monotonically increases. This shows the regularizing properties of the MSI, and the iteration number can be considered a regularization parameter.

The effect of the distribution of measurement points around the node on the accuracy of interpolation of the digital terrain model

Contemporary land information systems allow the generation of models of numerical surfaces by applying a number of interpolation algorithms. The appropriate selection of measurement points included in the calculations is one of the key factors influencing the quality and accuracy of interpolation. Properly selected points contribute to improving the accuracy of the generated surface models and to shortening the computation process. This paper analyzes the effect of the location and density of measurement points on the accuracy of interpolation surfaces in view of the morphological differentiation of the generated models.

Visual Processing of the River Cross-Sectional Data

The cross-section of Hydraulic engineering (river, embankment) is a kind of cross section which is always perpendicular to the river direction. Section line is a straight line which is created by connecting two endpoint of the section. Cross-section measurements is that collecting a coordinate point (X, Y, H) on the section line every a certain distance. Field measurement, due to the influence of the external environment, especially when measured in the river, is difficult to ensure that the location of the measurement point exactly on the straight line shown in the section. The reason is that tracking ship traveling along with the section will be impacted by the water, resulting in the offset along the flow direction. Therefore we must to constantly adjust the direction of travel in the measurement process. For which the measurement data should be processed. So it is necessary to deal with the measurement data, and the idea of visual data was proposed in the paper, which is easier to analyze the accuracy of the measurement data. The BUFFER analysis method was used in the data processing, which effectively removed measurement invalid point that far away from the cross-section in measurement and improved the accuracy of the cross-section data processing. On the other hand, the effective pedal point coordinates was used in the calculation of the plane location of cross-section point. The coordinate which can make the cross-section data more realistic and different from the translation of point and uniform distribution algorithm closeted to the effective point of measurement. The method that the elevation of pedal point on the cross section calculated using the distance weighted interpolation method has been applied in the measurement process of several rivers. It is proved in practice that the method got good results and achieved the accuracy of the data and quality which the application sector requirements on.

Ultrasonic Water Level Measurement System Based on GPS

An Ultrasonic water level measurement system based on GPS is presented. According to the ultrasonic principle and GPS positioning technology, the secondary ultrasonic reflection in the air and the time spent in the liquid are measured to calculate the height of the water level and the depth of the liquid. The temperature compensation circuit is designed to improve the measurement precision. The use of GPS, the specific location of measurement points can be got, and the key position multi-point level measurement, cycle monitoring, real-time monitoring and mobile monitoring can be achieved

Ultrasonic Water Level Measurement System Based on GPS

An Ultrasonic water level measurement system based on GPS is presented. According to the ultrasonic principle and GPS positioning technology, the secondary ultrasonic reflection in the air and the time spent in the liquid are measured to calculate the height of the water level and the depth of the liquid. The temperature compensation circuit is designed to improve the measurement precision. The use of GPS, the specific location of measurement points can be got, and the key position multi-point level measurement, cycle monitoring, real-time monitoring and mobile monitoring can be achieved

Temperature state recognition based on dynamical selection of measuring point location

In order to realize intelligent recognition of temperature state and related analysis for devices surface temperature states,an improved Analytic Hierarchy Process(AHP) model was introduced,which could dynamically analyze the relevance among several measuring points of temperature and selected key measuring point which could reflect the temperature state for devices.At the same time,Kohonen Self-Organizing Feature Map(SOFM) neural network was established,which could update and follow and recognize temperature serials value of key measuring points during some time,so that show device temperature status.Take traction motor for example,Matlab software simulation analysis show its recognition rate is 89%,which effectively reduces the false positive rate of fire.

Monitoring changes in lichen resources for range management purposes in reindeer husbandry

Mat-forming lichens are important as food source for reindeer during the winter, and thus a vital resource to manage in reindeer husbandry. In this paper we suggest a method for monitoring of changes in lichen height with the purpose to early detect changes in lichen abundance in reindeer grazing areas. The method is intended for measuring geographically uniform lichen areas, evenly used for reindeer grazing. We analysed spatial variations in lichen height at the meter and 100 m scales, and calculated sample size requirements, and estimated effects of forest density and age, lichen moisture and lichen density on lichen height, and assessed the correspondence between lichen height and biomass. The variation in lichen height differed considerably between sites and, hence, the required sample size to detect a 5 mm change in lichen height with a power of 0.95 ranged from 200 to 2000, depending on the standard deviation of measured heights. Based on the autocorrelation in lichen height found between adjacent measurement points, a minimum distance of 4 m between measurement points is also recommended. Lichen height was significantly affected by lichen moisture, and the results suggest that this effect of moisture might vary with lichen density. Lichen height varied spatially within the study sites, and the spatial variations were partly caused by forest age and density. Thus, gradual changes in the forest characteristics are likely to alter the spatial variation in lichen height and it is therefore important to regularly re-evaluate the locations of measurement points within the monitored area. This study provides suggestions for a variable that could be used as an indicator of changes in the lichen resource, and aspects that should be considered when designing a monitoring program. The accuracy of detecting changes depends on the monitoring efforts, i.e. the number and distribution of measurement points and how often an area is monitored. In conclusion, our results indicate that measurements of lichen height have considerable potential for monitoring of changes in lichen resources within reindeer husbandry.

Design of general-purpose sampling strategies for geometric shape measurement

Quality inspection is a preliminary step for different further analyses (process monitoring, control and optimisation) and requires one to select a measuring strategy, i.e., number and location of measurement points. This phase of data gathering usually impacts on inspection times and costs (via sample size) but it also affects the performance of the following tasks (process monitoring, control and optimisation). While most of the approaches for sampling design are specifically presented with reference to a target application (namely, monitoring, control or optimisation), this paper presents a general-purpose procedure, where the number and location of measurement points are selected in order to retain most of the information related to the feature under study. The procedure is based on principal component analysis and its application is shown with reference to a real case study concerning the left front window of a car. A different approach based on multidimensional scaling is further applied as validation tool, in order to show the effectiveness of the PCA solution.

SU‐GG‐T‐192: Automatic Ionization Chamber Measurement Points Selection for IMRT Point Dose QA

Purpose: This work is about a method to automatically select IC (ion‐chamber) QA measurement points. As a IMRT patient specific QA method, IC measurement is used to determine the absolute dose for delivery verification and monitor units (MU) correction purposes. Because of steep dose gradients, the locations of IC measurement points are critical. Manually selecting IC measurement points is a laborious and difficult work especially for highly modulated fields. Poor IC point selections often result in unnecessary failed measurements, or even inaccurate MU corrections. We therefore have developed a new and automatic method to determine the best IC measurement points. Methods: The key idea of the method is to rank the possible IC measurement points according to their local dose variations, and then to pick the best points. The local dose variation for a point is defined as the dose value range inside a 1 cm diameter sphere centered by the point. A composite ranking method is developed to include the local dose variation ratio, the absolute dose value, point location in the water phantom box, spatial distances and dose value differences from other good measurement points. In this way, the best multiple IC points can be determined not only based on the goodness of single point, but also to meet other dosimetry and physical requirements between the points. Results and conclusion: The method was firstly implemented and verified in MATLAB. we have ported it to Pinnacle scripts combined with C program, so to make it fully automated in Pinnacle TPS. It has been routinely used in our clinic for months. The results show that this method can speed up the IC QA planning process and reduce the rate of IC QA failures.

Sensitivity analysis of two-dimensional steady-state aquifer flow equations. Implications for groundwater flow model calibration and validation

This paper presents the analytical properties of the sensitivity of the two-dimensional, steady-state groundwater flow equation to the flow parameters and to the boundary conditions, based on the perturbation approach. These analytical properties are used to provide guidelines for model design, model calibration and monitoring network design. The sensitivity patterns are shown to depend on the nature of both the perturbed parameter and the variable investigated. Indeed, the sensitivity of the hydraulic head to the hydraulic conductivity extends mainly in the flow direction, while the sensitivity to the recharge spreads radially. Besides, the sensitivity of the flow longitudinal velocity to the hydraulic conductivity propagates in both the longitudinal and transverse directions, whereas the sensitivity of the flow transverse velocity propagates in the diagonal directions to the flow. The analytical results are confirmed by application examples on idealized and real-world simulations. These analytical findings allow some general rules to be established for model design, model calibration and monitoring network design. In particular, the optimal location of measurement points depends on the nature of the variable of interest. Measurement network design thus proves to be problem-dependent. Moreover, adequate monitoring well network design may allow to discriminate between the possible sources of error.

A tolerance interval based criterion for optimizing discrete point sampling strategies

Abstract In order to compute geometric tolerances, the distance between the actual geometry and the nominal one has to be computed, and this computation requires the selection of a sampling strategy. Sampling strategy consists in deciding the number and the locations of the points that have to be measured on the actual surface. This paper presents a new approach for selecting the optimal locations of the points for any given sample size. The proposed procedure is based on estimating the “manufacturing signature”, that is the systematic pattern left by the manufacturing process on the machined items. In particular, the proposed approach is based on using regression for estimating the manufacturing signature and then selecting the measurement point locations by minimizing the distance between the maximum and the minimum points of the regression-based tolerance interval. Performance of the proposed procedure are compared with those obtainable by selecting different strategies with reference to a case study related with roundness data. Given that the approach proposed outperforms the competitor ones, a robustness study is finally presented to show that the method presented is robust to violation of the assumption behind linear regression models.