Practical Measurement Technique Research Articles

A practical subcritical rod worth measurement technique based on the improved neutron source multiplication method

The control rod worth is a key safety parameter required to be measured in commercial pressurized water reactors (PWRs). Conventionally, the control rod worth is measured after reaching the critical state, which occupies the considerable time in the zero-power physics test. In this study, an efficient control-rod worth measurement technique has been proposed based on the improved neutron-source multiplication method, which can be implemented with the source-range detector count rates in the subcritical states. Moreover, the noise reduction technique has been adopted to smooth the large fluctuation existing in the original signals. In order to verify the engineering performance of the proposed measurement technique, the measured source-range detector count rates during the rod withdrawal process before reaching critical state in a CNP1000 reactor have been employed. It demonstrated that almost all estimated results of control rod worth satisfy the engineering acceptance criteria, except one control rod with the relative difference over 10 %, which indicates the capability of the proposed method in estimating control rod worth.

Experimental Investigation Techniques for Non-Ideal Compressible Fluid Dynamics

The rising number of applications of the organic Rankine cycle (ORC) or supercritical CO2 (sCO2) power systems have shaped a new branch of fluid mechanics called non-ideal compressible fluid dynamics (NICFD). This field of fluid mechanics is concerned with flows of vapors or gases, which are characterized by substantial deviations from the perfect gas model. In extreme cases, even non-classical gas dynamic phenomena could occur. Although these non-ideal compressible flows are the subject of sophisticated numerical simulation studies today, there is also a growing need for experimental data for validating purposes. In the last couple of years, new experimental test rigs designed for investigating non-ideal compressible fluid dynamics have been developed and commissioned. Classical practical measurement techniques are currently being re-developed and applied to non-ideal compressible flows. Despite its substantial relevance, information about these measurement techniques and their differences from conventional methods in the open literature is scarce. The present review article is an attempt to reduce that gap. After briefly discussing the thermodynamics and fluid dynamics of non-ideal compressible flows, the currently available test rigs and their utilized measurement techniques are reviewed. This review discusses schlieren optical investigations, pneumatic and laser-optical methods, and hot-wire anemometry for non-ideal compressible flows.

Population Diversity in Ant-inspired Optimization Algorithms

Finding a balance between exploration and exploitation is very important in the case of metaheuristics optimization, especially in the systems leveraging population of individuals expressing (as in Evolutionary Algorithms, etc.) or constructing (as in Ant Colony Optimization) solutions. Premature convergence is a real problem and finding means of its automatic detection and counteracting are of great importance. Measuring diversity in Evolutionary Algorithms working in real-value search space is often computationally complex, but feasible while measuring diversity in combinatorial domain is practically impossible (cf. Closest String Problem). Nevertheless, we propose several practical and feasible diversity measurement techniques dedicated to Ant Colony Optimization algorithms, leveraging the fact that even though analysis of the search space is at least an NP problem, we can focus on the pheromone table, where the direct outcomes of the search are expressed and can be analyzed. Besides proposing the measurement techniques, we apply them to assess the diversity of several variants of ACO, and closely analyze their features for the classic ACO. The discussion of the results is the first step towards applying the proposed measurement techniques in auto-adaptation of the parameters affecting directly the exploitation and exploration features in ACO in the future.

Field measurements for identification of modal parameters for high-rise buildings under construction or in use

The enhanced frequency domain decomposition (EFDD) method can yield different results with respect to modal parameters depending on the measurement and analysis conditions of the target building. Consequently, field measurement guidelines for EFDD are required. In this paper, a practical field measurement technique is proposed for the identification of modal parameters of high-rise buildings in use or under construction. Based on the modal analysis of the numerical analysis model and structural response from two high-rise buildings, the criterion for the lower bound and upper bound of the three measurement and analysis conditions from the modal analysis process were suggested as the minimum conditions for an enhanced frequency domain decomposition (MCEFDD) method. It was verified with structural responses from a 35-story building that the proposed MCEFDD method yields reliable model parameter results. The proposed MCEFDD method can be used for practical measurements of responses high-rise buildings in field.

Validation of a Practical Forearm Supination Strength Measurement Technique in the Large Sample Cohort.

The strength of forearm in pronation and supination (P/S) is an important clinical assessment during pre-operative examination as well as in post-operative evaluation. Many clinical trials concerning the measurement of forearm P/S strength were performed using a dynamometer fixed on the wall. The aim of this study was to bring out a simple and reliable technique for the measurement of P/S strength using a dynamometer manually supported and stabilized by an examiner. We hypothesized that there are no differences in evaluation of elbow P/S strength using the dynamometer fixed or the dynamometer stabilized by an operator in healthy people. The study was performed on a cross-sectional cohort of 100 healthy subjects without any history of injuries or previous surgery of the upper limbs. Isometric forearm P/S strengths were measured on the dominant and non-dominant forearms, using the dynamometer fixed on a table, and using the same dynamometer kept by an operator. The measurements were repeated in triplicate at 45°, 90° and 120° of elbow flexion in both upper limbs for all patients. A total of 100 subjects (50 females, 50 males) were included in the study group. The mean age was 46.5years (range 25-52years). Female and male subjects showed no significant differences concerning the mean age (F/M ratio 0.50/0.50). The mean body mass index of all participants was 24.34 ± 3.66kg/m2.No significant statistics difference was reported between the P/S strength measured using the two detection methods in our study group (45°, 90° and 120° of elbow flexion and both upper limbs). The manually stabilized technique is a valid and reliable technique to assess the P/S strength of the forearm. This is a simple and effective method that may be reproduced in our daily clinical practice as well as in sportive practice.

Assessing the dynamics of natural capital on farms: A soil natural capital indicator

Efficient management of natural resources and environmental assets requires adequate assessment of natural capital on farms. Conceptual frameworks and practical measurement techniques to assess the state of natural capital assets and ecosystem services on farms are not readily available. In this paper, we propose a natural capital adjusted productivity and efficiency technique that can be used in effectively measuring the dynamics of natural capital on farms. This on-farm natural capital indicator is constructed based on the directional distance functions approach. As an empirical application, this newly devised indicator is applied to determine how soil natural capital in farm production systems changes over time. Findings from this study will aid decision making to support maintaining higher farm productivity growth in agriculture and achieving environmental sustainability.

Unveiling femtosecond rogue-wave structures in noise-like pulses by a stable and synchronized time magnifier.

Mode-locked fiber lasers are an ideal platform for an ultrafast nonlinear physics study, and they have shown many intriguing, yet not fully understood, phenomena such as the optical rogue waves (ORWs) and noise-like pulses (NLPs). However, one of the major obstacles in the study of fiber laser dynamics is the lack of practical measurement techniques for round-trip tracking, and single-shot, real-time observation in the time domain at sub-picosecond (ps) resolution. Here we demonstrate an automatically synchronized characterization of NLPs using a parametric time magnifier. The round-trip evolution of ultrafast temporal structures in the noise-like pulses has been experimentally resolved at sub-ps resolution, to the best of our knowledge, for the first time, and ORWs have been identified.

A Novel <inline-formula> <tex-math notation="LaTeX">$\text{TM}_{0{n}}$</tex-math> </inline-formula> Mode Content and Relative Phase Analysis Technique

Overmoded relativistic backward wave oscillators (RBWOs) are usually difficult to achieve pure mode ouHowever, until now, radiation equipments for high power microwave (HPM) devices are only matched to a single operating mode. So it is unsuitable to utilize the ready-made HPM antenna to radiate mixed $\text{TM}_{0{n}}$ modes with high radiation efficiency, and thus practical applications of the overmoded RBWO device becomes limited. For converting these hybrid $\text{TM}_{0{n}}$ modes into a pure one (e.g., $\text{TM}_{01}$ or TEM mode), diagnostics of the overmoded RBWO's output mode is required. In this letter, a practical measurement technique without requiring high precision calibrations of the power distribution and relative phases between the $\text{TM}_{0{n}}$ modes propagating in overmoded waveguide is described. This method is validated by measuring the output modes of a specially designed $\text{TM}_{01}\!-\!\text{TM}_{0{n}}$ mixed modes exciter.

Thickness identification of epitaxial Bi2Te3 via optical contrast

Two-dimensional (2D) nanosheet thickness identification is effective for rapidly determining thickness-dependent properties of 2D materials. Bismuth telluride (Bi2Te3) is a 2D material known for its promising thermoelectric properties and potential dissipationless charge transport in the topological surface states. To date, thickness measurements of Bi2Te3 2D nanosheets are mainly carried out via atomic force microscope or Raman spectroscopy. Here, we investigate a practical, rapid, inexpensive, and non-invasive thickness measurement technique that utilizes the optical contrast of Bi2Te3 2D nanosheets on a mica substrate (i.e., as-grown) and a SiO2/Si substrate (i.e., transferred). The reflected optical intensity and the corresponding contrast are studied as a function of Bi2Te3 thickness, illumination wavelength, and substrate thickness. Disagreement between experimental and calculated optical contrast values is observed, which is ascribed to the thickness-dependent refractive indices of Bi2Te3, mica thickness error, and the deviation from normal light incidence. Despite thin film interference in mica, the monotonic relationship between nanosheet’s contrast and thickness makes mica a better substrate for identifying Bi2Te3 thickness. In addition, a brief recipe is provided for such a thickness identification method to be generally applied in any laboratory.

Assessment of atrial septal defect size with three-dimensional volumetric measurement of cardiac CT: comparison with size of the postoperative occluder

Objective To evaluate two kinds of practical CT three-dimensional volumetric measurement techniques in assessing atrial septal defects (ASDs) for transcatheter device closure. Methods Retrospective assessment of 50 consecutive patients who underwent ASD closure was conducted.Cardiac CT was performed in them before planned transcatheter ASD closure and postoperative chest radiograph was performed in both posteroanterior and lateral view.Coronary CT angiography was made for the detection of coronary artery disease,and three-dimensional reconstruction of ASD was conducted for determination of the defect size in the GE-workstation.Two kinds of practical CT three-dimensional volumetric measurement techniques,one named CT virtual endoscopy assisted volumetric measurement (CTVE) and another called axial sequence assisted volumetric measurement (CTAS),were used to calculate the major axis and the minor axis of the ASD respectively.Thus,the dimensions of the Equivalent Circle were derived,with circumference and area equal to the elliptic ASD according to the formulation (D= b4/a2+ a2-b2).The ASDs occluder (ASO) dimension was measured in the lateral chest radiograph,and this postoperative occluder-waist size (POS) value was regarded as the gold standard for the measurement of ASD.The results were compared between CTVE and CTAS,and the correlations were evaluated between them and the gold standard. Results The differences in the major dimensions (-9.05 mm,t=-6.60,P<0.05),minor dimensions (-4.86 mm,t=-4.39,P<0.05) and Equivalent circle dimensions (-7.65 mm,t=-6.40,P<0.05) of ASD between CTAS and CTVE were statistically significant.Though the CTAS cannot provide the en face views of ASDs,the Equivalent Circle dimensions measured by CTAS (22.48±5.59) mm was correlated well with POS (27.07±6.83) mm (Y=1.14X+ 1.39,r=0.94,P<0.01),and a good correlation was found between this Equivalent Circle dimensions and ASO size (Y=1.02X+ 6.84,R 2=0.78,r=0.88,P<0.05).The correlation between the Equivalent Circle dimensions measured by using CTVE (30.13±9.27) mm and POS was poor (Y=0.30X+ 17.94,r=0.41,P<0.01),though it can provide the en face views of ASDs. Conclusion CTVE and CTAS are two complementary techniques of assessing ASDs for transcatheter device closure. Key words: Heart septal defects,atrial; Heart catheterization; Septal occluder device; Imaging three-dimensional; Tomography,X-ray computed

Twentieth-Century Length: The Origins, Use, and Formalization of Electromagnetic Standards

There was a fundamental change in our standards of length during the twentieth century, as the metal bars that had served for so long gave way to standards based on the wavelength, and then velocity, of light. This article describes those changes with particular emphasis on the standards-in-use of practitioners at the frontier of precision: spectroscopists, industrialists, geodesists, and astronomers. It reveals a multiplicity of de facto standards that supported their various innovations in practical electromagnetic measurement techniques. These de facto standards often came before, and guided the adoption of, the more visible new de jure standards that have been the subject of greater historical attention. I also offer a new explanation of the processes of change in our standards of length, based not simply on the search for better precision but more on concepts of mutual grounding and coherence.

Dynamic recalibration of scalable fringe-projection systems for large-scale object metrology

Three-dimensional (3D) surface shape measurement is a vital component in many industrial processes. The subject has developed significantly over recent years and a number of mainly noncontact techniques now exist for surface measurement, exhibiting varying levels of maturity. Within the larger group of 3D measurement techniques, one of the most promising approaches is provided by those methods that are based upon fringe analysis. Current techniques mainly focus on the measurement of small and medium-scale objects, while work on the measurement of larger objects is not so well developed. One potential solution for the measurement of large objects that has been proposed by various researchers is the concept of performing multipanel measurement and the system proposed here uses this basic approach, but in a flexible form of a single moveable sensor head that would be cost effective for measuring very large objects. Most practical surface measurement techniques require the inclusion of a calibration stage to ensure accurate measurements. In the case of fringe analysis techniques, phase-to-height calibration is required, which includes the use of phase-to-height models. Most existing models (both analytical and empirical) are intended to be used in a static measurement mode, which means that, typically, a single calibration is performed prior to multiple measurements being made using an unvarying system geometry. However, multipanel measurement strategies do not necessarily keep the measurement system geometry constant and thus require dynamic recalibration. To solve the problem of dynamic recalibration, we propose a class of models called hybrid models. These hybrid models inherit the basic form of analytical models, but their coefficients are obtained in an empirical manner. The paper also discusses issues associated with all phase-to-height models used in fringe analysis that have a quotient form, identifying points of uncertainty and regions of distortion as issues affecting accuracy in phase maps produced in this manner.

The 4D microgravity method for waterflood surveillance: Part 3 — 4D absolute microgravity surveys at Prudhoe Bay, Alaska

The 4D microgravity method is becoming a mature technology. A project to develop practical measurement and interpretation techniques was conducted at Prudhoe Bay, Alaska, from 1994 through 2002. Beginning in 2003 these techniques have been systematically applied to monitor a waterflood in the gas cap of the Prudhoe Bay reservoir. Approximately 300 stations in a [Formula: see text] area are reoccupied in each survey year with sub-[Formula: see text] precision absolute gravity and centimeter precision Global Positioning System (GPS) geodetic measurements. The 4D gravity measured over epochs 2005–2003, 2006–2003, and 2007–2003 has been successfully modeled to track the mass of water injected since late in 2002. A new and improved version of the A-10 field-portable absolute gravity meter was developed in conjunction with this project and has proven to be a key element in the success of the 4D methodology. The use of an absolute gravity meter in a field survey of this magnitude is unprecedented. There are substantial differences between a 4D absolute microgravity survey and a conventional gravity survey in terms of station occupation procedures, GPS techniques, and the 4D elevation correction. We estimate that the overall precision of the 4D gravity signal in each epoch is less than [Formula: see text].

Spatial variations of sensible heat flux over an urban area measured using Doppler lidar

AbstractThe terrain and morphology of an urban area have a major impact upon the distribution of sensible heat flux and consequently the energy balance of the boundary layer. The spatial distribution of sensible heat flux is difficult to measure, particularly in cities. In this article the potential of a scanning Doppler lidar to make these measurements is explored. The measurements of sensible heat flux are interpreted using a simple trajectory model and an energy balance model. The lidar does seem to offer a practical measurement technique, although the system employed in this study does not have sufficient resolution to provide detailed values over small areas. Copyright © 2008 Royal Meteorological Society

Noninvasive Assessment of Cytokines in Occupational Respiratory Diseases

A major goal in studying occupational respiratory diseases is to show relationships between occupational exposures and health outcomes. Due to the nature of these diseases, accurate, practical, and objective measurement techniques are needed in field investigations. Pulmonary function tests, such as spirometry, are important objective health outcome measures. However, they reflect the functional changes of the lung, often in relatively late stages, which may be irreversible. Direct monitoring of airways inflammations, in response to occupational exposures, are receiving an increasing attention since they may pick up inflammatory changes before the injury becomes irreversible. Invasive approaches such as bronchoalveolar lavage and bronchial biopsies have been used to assess airways inflammation: but these methods are not practical for use in occupational field investigations. Thus, much work has focused on the development of noninvasive methods for monitoring inflammation in occupational respiratory diseases. The three recent most commonly used noninvasive techniques in occupational respiratory diseases investigations are induced sputum, exhaled breath condensate, and nasal lavage. In this review, we discuss the practical application of these techniques, patents and cytokines measured with them. Since variation of cytokine genes contribute to the inflammatory processes, we briefly discuss the genetic polymorphisms on the expression of occupational respiratory diseases. Details of genetic polymorphism were beyond the focus of this review. Our primary focus was cytokines measured with these three noninvasive techniques in occupational respiratory investigations.

The role of degassing in XLPE power cable manufacture

This article focuses on a range of elements critical to this process; form the fundamental chemistry, through computational and measurement techniques to the solutions that are in use today. Degassing contributes greatly to the quality of power cables by improving the certainty in electrical testing and improving the dielectric properties. To ensure that the degassing process delivers the expected benefits, it is important to measure and model the process by which the crosslinking byproducts are desorbed from the cable polymers. Weight loss and HPLC have shown themselves to be the most effective and practical measurement techniques

Revisiting spurious-free dynamic range of communication receivers

The spurious free dynamic range (SFDR) is commonly used as a measure of dynamic range for the radio frequency and microwave front-end receivers. Although well defined in narrow-band systems, the definition becomes less clear in wide-band systems, when the nonlinearity is memoryless and the the noise figure is frequency dependent. To generalize the SFDR to wide-band systems, a meaningful physical interpretation of the conventional two-tone test is first developed. Based on this interpretation, the upper bound of the wide-band SFDR is obtained by applying a multitone test, while the lower bound is computed using the effective noise figure. The multitone test in both the memoryless and memory nonlinear Volterra systems is considered. A practical measurement technique to characterize the Volterra kernel is also provided. A realistic example based on a low noise amplifier shows a significant difference between the conventional and wide-band SFDR values. In this example, our results suggest that the use of two tones widely separated in frequency to model the interferers provides sufficiently accurate results compared to a multitone approximation.

Current distribution mapping in polymer electrolyte fuel cells—A finite element analysis of measurement uncertainty imposed by lateral currents

Using the finite element method, lateral currents in two different configurations for current distribution mapping in polymer electrolyte fuel cells (PEFCs) were simulated and the impact on the accuracy of measurement was analysed. The measurement techniques were of a conventional and a newly developed type, based on a segmented bipolar plate (BPP), respectively, a non-segmented bipolar plate combined with a printed circuit board (PCB). In both cases, neither the membrane electrode assemblies (MEAs) nor the gas diffusion layers (GDLs) were segmented and local currents were detected passively. The resistance of the measurement circuit and the current density gradient between neighbouring segments were found to be the major parameters causing current spreading. As expected, a significantly higher uncertainty of measurement could be observed and experimentally verified for the non-segmented bipolar plate. However, the accuracy is increasing with increasing homogeneity of the current density distribution. Achieving a uniform utilisation of the active area is a major task in fuel cell development and approaching this objective also improves the quality of measurement. Consequently, the application of non-segmented bipolar plates as highly flexible and practical measurement technique is a suitable option for current distribution mapping in technically relevant single cells and fuel cell stacks.

Virtual technologies for advanced manufacturing and metrology

The concept of virtual technologies is not one that is common when associated with length metrology. However, there are a number of techniques that are becoming used to an increasing extent in industry and in research. For example, the virtual metrology frame is becoming a practical measurement technique for accurate measurement and the virtual Coordinate Measuring Machine (CMM) is in its early stages of providing an effective means of uncertainty evaluation. These technologies are described in this paper.

New practical dispersion measurement technique for Bragg grating based MZI-OADM

A new technique is presented to accurately determine the mean dispersion of Bragg gratings written in Mach-Zehnder interferometer arms. It could be used to control the dispersion of a Bragg grating based optical add-drop multiplexer. The letter will illustrate the preliminary experimental results.