Evaluation of Dosimetric Impact of Uncertainty of Measurement in Estimating External Radiotherapy Dose

Cancer is a major societal public health and economic problem, responsible for one in every six deaths. Radiotherapy is the main technique of treatment for more than half of cancer patients. To achieve a successful outcome, the radiation dose must be delivered accurately and precisely to the tumor, within ± 5% accuracy. Smaller uncertainties are required for better treatment outcome. The objective of the study is to investigate the uncertainty of measurement of external radiotherapy beam using a standard ionization chamber under reference conditions. Clinical farmers type ionization chamber measurement was compared against the National Reference standard, by exposing it in a beam 60Co gamma source. The measurement set up was carried out according to IAEA TRS 498 protocol and uncertainty of measurement evaluated according to GUM TEDDOC-1585. Evaluation and analysis were done for the identified subjects of uncertainty contributors. The expanded uncertainty associated with 56 mGy/nC ND,W was found to be 0.9% corresponding to a confidence level of approximately 95% with a coverage factor of k = 2. The study established the impact of dosimetry uncertainty of measurement in estimating external radiotherapy dose. The investigation established that the largest contributor of uncertainty is the stability of the ionization chamber at 36%, followed by temperature at 22% and positioning of the chamber in the beam at 8%. The effect of pressure, electrometer, resolution, and reproducibility were found to be minimal to the overall uncertainty. The study indicate that there is no flawless measurement, as there are many prospective sources of variation. Measurement results have component of unreliability and should be regarded as best estimates of the true value. .

Measurement Uncertainty Analysis of the Rotary-scan Method for the Measurable Dimension of Cylindrical Workpieces

The measurement uncertainty analysis is carried out to investigate the measurable dimensions of cylindrical workpieces by the rotary-scan method in this paper.Due to the difficult alignment of the workpiece with a diameter of less than 3 mm by the rotary scan method,the measurement uncertainty of the cylindrical workpiece with a diameter of 3 mm and length of 50 mm which is measured by a roundness measuring machine,is evaluated according to GUM(Guide to the Expression of Uncertainty in Measurement)as an example.Since the uncertainty caused by the eccentricity of the measured workpiece is different with the dimension changing,the measurement uncertainty of cylindrical workpieces with other dimensions can be evaluated the same as the diameter of 3 mm but with different eccentricity.Measurement uncertainty caused by different eccentricities concerning the dimension of the measured cylindrical workpiece is set to simulate the evaluations.Compared to the target value of the measurement uncertainty of 0.1μm,the measurable dimensions of the cylindrical workpiece can be obtained.Experiments and analysis are presented to quantitatively evaluate the reliability of the rotary-scan method for the roundness measurement of cylindrical workpieces.

Item-Level Analysis of the Revised Occupational Therapy Fieldwork Performance Evaluation Applied in Practice

Competency-based assessments for healthcare professionals are critical for safe and effective client outcomes. Rehabilitation clinical skill competency assessments must be validated and revised to produce safe and skilled practitioners. The revised American Occupational Therapy Association (AOTA) Fieldwork Performance Evaluation (FWPE) instrument measures occupational therapy student performance to determine readiness for practice. The assessment includes thirty-seven competencies that address both profession specific clinical skills and general professional behavior skills. The objective of this study was to use Rasch methods to explore the use of the revised FWPE in actual fieldwork practice and to determine the instrument’s psychometric properties when separating the item components into two distinct subdomains: General Health Professions Competences and Occupational Therapy-Specific Competencies. Internal construct validity and test reliability were analyzed using data from 149 occupational therapy students after completing their initial Level II A fieldwork clinical internship. This study examined the item difficulty hierarchy, item fit, person-fit to model, person separation index, person separation reliability coefficient, strata, ceiling and floor effect, and unidimensionality of the FWPE instrument as a whole and as two separate domains. With the exception of not meeting the criteria for unidimensionality, the full FWPE instrument and the Occupational Therapy-Specific Competencies subdomain showed acceptable item-level psychometrics for reliability and precision. While the General Health Professions Competencies subdomain showed good item-level psychometrics, it was below the criterion for reliability and only separated the sample into two strata. Results support the validity, reliability, and clinical use of the revised FWPE full instrument and the Occupational Therapy-Specific Competencies subdomain to measure entry-level clinical skill competencies in practice.

Measurement Uncertainty Assessment for Determination of Allura Red in Puffed Food by HPLC

This study aimed to assess the measurement uncertainty of a new method for determination of allura redin food by high performance liquid chromatography （HPLC）. The uncertainty of mathematical model of allura red is based on Europe for Analytical Chemistry（EURACHEM） guidelines. The sources and components of uncertainty were calculated, including recovery, working solution, sample mass, final volume, response of standard solution, response of sample solution. The expanded uncertainty was 0.0024 （k=2）. Uncertainty of working solution was the most significant factor contributing to the total uncertainty, accounting for 86.2%. The uncertainty of volume accounted for the minimum at 0.025%. The developed method is simple and accurate, which can be used for the determination of allura redin puffed samples.

Analysis and Applications of the Measurement Uncertainty in Electrical Testing

Recently, uncertainty measurement is more and more recognizable in modern data management, conformity assessment, and laboratory accreditation system because of its importance. In this paper, a set of reasonable probability explanations are introduced and an effective method is pro- posed to quantify the assessment indices for the uncertainty measurement of electrical testing laboratory. First of all, the influence from uncertainty factors during the test process is taken into account. With the use of ISO/IEC Guide 98-3 standard and probability theory, the index and model for the measurement uncertainty assessment of a laboratory is then derived. From the simulation results of safety testing, laboratory uncertainty measurement assessment activity for actual electrical appliances, and the confirmation of Monte Carlo simulation method, the appropriateness and correctness of proposed method are verified.

The Evaluation of Measurement Uncertainty and Its Application in the Vacuum Pressure Measurement

In order to accurately measure the pressure and the pressure difference between two points in the vacuum chamber, a large number of experimental data were used to research the performance of the three capacitance diaphragm gauge and analysis the main influences of the uncertainly degree of pressure in the process. In this paper, three kind of uncertainty, such as the single uncertainty, the synthesis uncertainty and the expanded uncertainty of the three capacitance diaphragm gauges are introduced in detail in pressure measurement. The results show that the performance difference of capacitance diaphragm gauge can be very influential to the accuracy of the pressure difference measurement and the uncertainty of different pressure can be very influential to pressure measurement. That for accurately measuring pressure and pressure difference has certain reference significance.

The Measurement and Uncertainty Analysis of Antenna Factor of Microwave Antennas Based on Standard Site Method

A method of Standard Site Method (SSM) in the American National Standards Institute’s ANSI C63.5 is described in the frequency ranges from 30 MHz to 1000 MHz. And a measurement system is set up for determining antenna factors (AF) of antennas on an Open Area Test Sites (OATS). AF of antennas including log-periodic antenna and biconical antenna is measured with SSM method by Shanghai Institute of Measurement and Testing Technology (SIMT), which shows good agreement to data measured by National Institute of Metrology (NIM). In the end, it analyzes the measurement uncertainty of SIMT in the 30 MHz to 1000 MHz frequency band and does comparison to that of NIM.

Theoretical analysis and verification of uncertainty of measurement on a cantilever coordinate measuring machine

A cantilever coordinate measuring machine(CCMM)is proposed according to the in-situ measurement requirement of workpieces with complex structures limited by the finite space of the5-axes computerized numerical control(CNC)processing site.Factors affecting uncertainty of measurement(UM)are classified and analyzed on the basis of uncertainty evaluation criteria,and the estimation technique of UM for measuring systems is presented.UM of the CCMM is estimated from the factors such as temperature,error motions as well as the mechanism deformations.Measurement results show that the actual measurement error is smaller than that of measurement requirement.

Research into Uncertainty in Measurement of Seawater Chemical Oxygen Demand by Potassium Iodide-Alkaline Potassium Permanganate Determination Method

Using the glucose and L-glutamic-acid to prepare the standard substance according to the ratio of 1：1, and the artificial seawater and the standard substance to prepare a series of standard solutions, the distribution pattern of uncertainty in measurement of seawater COD is obtained based on the measured results of the series of standard solutions by the potassium iodide-alkaline potassium permanganate determination method. The distribution pattern is as follows： Uncertainty in measurement is big and not constant at the high end, but small and constant at the low end.

Belief reliability:a scientific exploration of reliability engineering

This paper systematically introduces and reviews a scientific exploration of reliability called the belief reliability.Beginning with the origin of reliability engineering,the problems of present theories for reliability engineering are summarized as a query,a dilemma,and a puzzle.Then,through philosophical reflection,we introduce the theoretical solutions given by belief reliability theory,including scientific principles,basic equations,reliability science experiments,and mathematical measures.The basic methods and technologies of belief reliability,namely,belief reliability analysis,function-oriented belief reliability design,belief reliability evaluation,and several newly developed methods and technologies are sequentially elaborated and overviewed.Based on the above investigations,we summarize the significance of belief reliability theory and make some prospects about future research,aiming to promote the development of reliability science and engineering.

Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation

The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC test.However,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC method.To address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement campaigns.Hence,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC tests.We performed five case studies using OC test data made at a nuclear waste repository research site of Sweden.The results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.

Influencing factors and prevention measures of casing deformation in deep shale gas wells in Luzhou block,southern Sichuan Basin,SW China

Based on structural distribution and fault characteristics of the Luzhou block,southern Sichuan Basin,as well as microseismic,well logging and in-situ stress data,the casing deformation behaviors of deep shale gas wells are summarized,and the casing deformation mechanism and influencing factors are identified.Then,the risk assessment chart of casing deformation is plotted,and the measures for preventing and controlling casing deformation are proposed.Fracturing-activated fault slip is a main factor causing the casing deformation in deep shale gas wells in the Luzhou block.In the working area,the approximate fracture angle is primarily 10°-50°,accounting for 65.34%,and the critical pore pressure increment for fault-activation is 6.05-9.71 MPa.The casing deformation caused by geological factors can be prevented/controlled by avoiding the faults at risk and deploying wells in areas with low value of stress factor.The casing deformation caused by engineering factors can be prevented/controlled by:(1)keeping wells avoid faults with risks of activation and slippage,or deploying wells in areas far from the faulting center if such avoidance is impossible;(2)optimizing the wellbore parameters,for example,adjusting the wellbore orientation to reduce the shear force on casing to a certain extent and thus mitigate the casing deformation;(3)optimizing the casing program to ensure that the curvature radius of the curved section of horizontal well is greater than 200 m while the drilling rate of high-quality reservoirs is not impaired;(4)optimizing the fracturing parameters,for example,increasing the evasive distance,lowering the single-operation pressure,and increasing the stage length,which can help effectively reduce the risk of casing deformation.

Objective Model Selection in Physics: Exploring the Finite Information Quantity Approach

Traditional methods for selecting models in experimental data analysis are susceptible to researcher bias, hindering exploration of alternative explanations and potentially leading to overfitting. The Finite Information Quantity (FIQ) approach offers a novel solution by acknowledging the inherent limitations in information processing capacity of physical systems. This framework facilitates the development of objective criteria for model selection (comparative uncertainty) and paves the way for a more comprehensive understanding of phenomena through exploring diverse explanations. This work presents a detailed comparison of the FIQ approach with ten established model selection methods, highlighting the advantages and limitations of each. We demonstrate the potential of FIQ to enhance the objectivity and robustness of scientific inquiry through three practical examples: selecting appropriate models for measuring fundamental constants, sound velocity, and underwater electrical discharges. Further research is warranted to explore the full applicability of FIQ across various scientific disciplines.

Penetration Study of Key Technologies for Cybersecurity Risk Assessment

In recent years,with the frequent occurrence of cyber security incidents,people have paid more attention to it.Information security risk assessment is a very important research topic.This paper gives a brief overview of the theory of cybersecurity risk assessment,focuses on the description of the current mainstream cybersecurity risk assessment methods,classifies and compares the existing methods according to the nature of the methods,and analyses the advantages,disadvantages,and application scope of each method.Finally,the main factors affecting the evaluation results are summarized and refined,and future research hotspots in this field are proposed.Through the empirical analysis of the three factors,the influence of the correlation of the three factors,the uncertainty of the evaluation indexes,and the timeliness of the evaluation on the evaluation results are concluded,which provides a reference for future research on evaluation methods.

Assessment of first-order-moment-based sample reconstruction method for design flood estimation in changing environment

Estimating the design flood under nonstationary conditions is challenging. In this study, a sample reconstruction approach was developed to transform a nonstationary series into a stationary one in a future time window (FTW). In this approach, the first-order moment (EFTW) of an extreme flood series in the FTW was used, and two possible methods of estimating EFTW values in terms of point values and confidence intervals were developed. Three schemes were proposed to analyze the uncertainty of design flood estimation in terms of sample representativeness, uncertainty from EFTW estimation, and both factors, respectively. To investigate the performance of the sample reconstruction approach, synthesis experiments were designed based on the annual peak series of the Little Sugar Creek in the United States. The results showed that the sample reconstruction approach performed well when the high-order moment of the series did not change significantly in the specified FTW. Otherwise, its performance deteriorated. In addition, the uncertainty of design flood estimation caused by sample representativeness was greater than that caused by EFTW estimation.

Uncertainty analysis of flow rate measurement for multiphase flow using CFD

The venturi meter has an advantage in its use,because it can measure flow without being much affected by the type of the measured fluid or flow conditions.Hence,it has excellent versatility and is being widely applied in many industries.The flow of a liquid containing air is a representative example of a multiphase flow and exhibits complex flow characteristics.In particular,the greater the gas volume fraction（GVF）,the more inhomogeneous the flow becomes.As a result,using a venturi meter to measure the rate of a flow that has a high GVF generates an error.In this study,the cause of the error occurred in measuring the flow rate for the multiphase flow when using the venturi meter for analysis by CFD.To ensure the reliability of this study,the accuracy of the multiphase flow models for numerical analysis was verified through comparison between the calculated results of numerical analysis and the experimental data.As a result,the Grace model,which is a multiphase flow model established by an experiment with water and air,was confirmed to have the highest reliability.Finally,the characteristics of the internal flow Held about the multiphase flow analysis result generated by applying the Grace model were analyzed to find the cause of the uncertainty occurring when measuring the flow rate of the multiphase flow using the venturi meter.A phase separation phenomenon occurred due to a density difference of water and air inside the venturi,and flow inhomogeneity happened according to the flow velocity difference of each phase.It was confirmed that this flow inhomogeneity increased as the GVF increased due to the uncertainty of the flow measurement.

Measurement Uncertainty Evaluation of Conicity Error Inspected on CMM

The cone is widely used in mechanical design for rotation, centering and fixing. Whether the conicity error can be measured and evaluated accurately will directly influence its assembly accuracy and working performance. According to the new generation geometrical product specification（GPS）, the error and its measurement uncertainty should be evaluated together. The mathematical model of the minimum zone conicity error is established and an improved immune evolutionary algorithm（IlEA） is proposed to search for the conicity error. In the IIEA, initial antibodies are firstly generated by using quasi-random sequences and two kinds of affinities are calculated. Then, each antibody clone is generated and they are self-adaptively mutated so as to maintain diversity. Similar antibody is suppressed and new random antibody is generated. Because the mathematical model of conicity error is strongly nonlinear and the input quantities are not independent, it is difficult to use Guide to the expression of uncertainty in the measurement（GUM） method to evaluate measurement uncertainty. Adaptive Monte Carlo method（AMCM） is proposed to estimate measurement uncertainty in which the number of Monte Carlo trials is selected adaptively and the quality of the numerical results is directly controlled. The cone parts was machined on lathe CK6140 and measured on Miracle NC 454 Coordinate Measuring Machine（CMM）. The experiment results confirm that the proposed method not only can search for the approximate solution of the minimum zone conicity error（MZCE） rapidly and precisely, but also can evaluate measurement uncertainty and give control variables with an expected numerical tolerance. The conicity errors computed by the proposed method are 20%-40% less than those computed by NC454 CMM software and the evaluation accuracy improves significantly.

Reservoir Porosity Measurement Uncertainty and its Influence on Shale Gas Resource Assessment

Reservoir porosity is a critical parameter for the process of unconventional oil and gas resources assessment. It is difficult to determine the porosity of a gas shale reservoir, and any large deviation will directly reduce the credibility of any shale gas resources evaluation. However, there is no quantitative explanation for the accuracy of porosity measurement. In this paper, measurement uncertainty, an internationally recognized index, was used to evaluate the results of porosity measurement of gas shale plugs, and its impact on the credibility of shale gas resources assessment was determined. The following conclusions are drawn:(1) the measurement uncertainty of porosity of a shale plug is 1.76%–3.12% using current measurement methods, the upper end of which is too large to be acceptable. It is suggested that the measurement uncertainty should be factored into the standard helium gas injection porosity determination experiment, and the uncertainty should be less than 2.00% when using a high-precision pressure gauge;(2) in order to reduce the risk for exploration and decision-making, attention should be paid to the large uncertainty(30% at least) of shale gas resource assessment results, sometimes with corrections being made based on the practical considerations;(3) a pressure gauge with an accuracy of 0.25% of the full scal cannot meet the requirements of porosity measurement, and a high-precision plug cutting method or high-precision bulk volume measurement method such as one using 3 D scanning, is recommended to effectively reduce porosity uncertainty;(4) the method and process for evaluating the measurement uncertainty of gas shale porosity could also be referred for assessment of experimental quality by other laboratories.

Risk assessment model of tunnel water inrush based on improved attribute mathematical theory

Tunnel water inrush is one of the common geological disasters in the underground engineering construction.In order to effectively evaluate and control the occurrence of water inrush,the risk assessment model of tunnel water inrush was proposed based on improved attribute mathematical theory.The trigonometric functions were adopted to optimize the attribute mathematical theory,avoiding the influence of mutation points and linear variation zones in traditional linear measurement functions on the accuracy of the model.Based on comprehensive analysis of various factors,five parameters were selected as the evaluation indicators for the model,including tunnel head pressure,permeability coefficient of surrounding rock,crushing degree of surrounding rock,relative angle of joint plane and tunnel section size,under the principle of dimension rationality,independence,directness and quantification.The indicator classifications were determined.The links among measured data were analyzed in detail,and the objective weight of each indicator was determined by using similar weight method.Thereby the tunnel water inrush risk assessment model is established and applied in four target segments of two different tunnels in engineering.The evaluation results and the actual excavation data agree well,which indicates that the model is of high credibility and feasibility.