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Magnetic field measurement is fundamental to nuclear magnetic resonance rotation sensors (NMRRS). A phase-locked loop (PLL)-based measurement with two nuclear isotopes is commonly applied to observe the magnetic field. However, the phase-loop and frequency-loop of the nuclear isotopes cannot be optimized simultaneously by a PLL-based method. In this paper, an approach based on a linear active disturbance rejection controller (LADRC) is proposed for synchronous phase-loop control of the two nuclear isotopes. Meanwhile, the frequencies of the nuclear isotopes are observed by linear extended state observers (LESOs). The phase and frequency loops can be decoupled and optimized with the proposed method. An experimental NMRRS prototype used for verification is built. The effectiveness and the feasibility of the proposed method are validated with the experimental results.

This study aimed to validate eye temperature (ET) assessed using infrared thermography (IRT) as an indicator of welfare in horses. Moreover, this study aimed to determine the most accurate position for ET measured using IRT and to validate this approach as a gold-standard measurement method. As the quantitative data obtained by IRT have strongly influenced the ET results depending on the specific location of the measurement area, an accurate definition of the regions of interest (ROI) was established. A total of 176 horses (Thoroughbred, Warmblood, and Halla horses) were used at the racing course of the Korea Racing Authority and public horse-riding clubs in South Korea. The present study also compared temperatures among three ROIs of the eye—lacrimal sac, medial canthus, and lateral canthus—at rest. Correlations between ET, rectal temperature (RT), heart rate (HR), and respiratory rate (RR) were assessed. There were no significant correlations between HR, RR or RT, however, among the three ROIs, the temperature of the medial canthus was positively correlated with RT (p &lt, 0.05). Furthermore, the size of ROI was negatively correlated with accuracy of temperature measurement. These results indicate that the most suitable area for ET measurement using IRT in horses is the medial canthus, and it is recommended to use the average temperature of the smallest ROIs (2 × 2 pixels) for temperature analysis. Therefore, this study offers a validated protocol in which ET measured using IRT in the horses is useful as an indicator of welfare.

Mass flow meters (MFMs) are widely used to secure reliable flow rates based on the mass value of the gas being measured. However, chemical reactions produce various kinds of gases, and their composition also changes in real time. Thus, there may be a large deviation in the gas flow if the gases’ composition and its mixing ratio are not known. In this study, we derived a gas flow rate measurement method using a chemically stable chemical specie and verified the precision of the proposed method through comparative analysis with an MFM. The flow rate by this method showed reliable results in both single and mixed gases. Notably, the results were within ±2.74% of the injected flowrate values in the gas mixtures. This method is expected to be able to fundamentally overcome the limitations of the mechanical flowmeter because it is not affected by changes in gas composition or mixing ratio during the reaction.

A Wheeler method for the evaluation of the radiation efficiency of submerged antennas within lossy media is presented and demonstrated for the first time in the literature. Extensive investigations have been devised by empirical and simulation methods. Normal-mode helical antenna (NMHA) was first designed and fabricated to exemplify a real-life application at the UHF band (0.3 to 3 GHz). The antenna under test (AUT) was evaluated within an artificial lossy material using a series of Wheeler caps featuring different radii to study the validity of this method. The error between the experimental and simulation radiation efficiency is below 3% near the theoretical radian length. The presented measurement method of radiation efficiency without any essential measurement facilities or accessories could be a promising candidate for fast and accurate evaluation for any wire-type antenna submerged within lossy media.

Consumer products contain chemical substances that threaten human health. The zero-dimensional modeling methods and experimental methods have been used to estimate the inhalation exposure concentration of consumer products. The model and measurement methods have a spatial property problem and time/cost-consuming problem, respectively. For solving the problems due to the conventional methodology, this study investigated the feasibility of applying computational fluid dynamics (CFD) for the evaluation of inhalation exposure by comparing the experiment results and the zero-dimensional results with CFD results. To calculate the aerosol concentration, the CFD was performed by combined the 3D Reynolds averaged Navier&ndash, Stokes equations and a discrete phased model using ANSYS FLUENT. As a result of comparing the three methodologies performed under the same simulation/experimental conditions, we found that the zero-dimensional spray model shows an approximately five times underestimated inhalation exposure concentration when compared with the CFD results and measurement results in near field. Additionally, the results of the measured concentration of aerosols at five locations and the CFD results at the same location were compared to show the possibility of evaluating inhalation exposure at various locations using CFD instead of the experimental method. The CFD results according to measurement positions can rationally predict the measurement results with low error. In conclusion, in the field of exposure science, a guideline for exposure evaluation using CFD, was found that complements the shortcomings of the conventional methodology, the zero-dimensional spray model and measurement method.

In the case of automated guided vehicles using odometry, a very important issue is to know the actual rolling radius of the wheel used to calculate the position of the vehicle. This radius is not constant. Its changes depend on the elastic deformation of the band layer and wheel slip. The theoretical determination of the value of the radius and the nature of the change is very difficult. For this reason, it was decided to determine the rolling radii by the experimental method. For this purpose, an appropriate test stand was built and the proposed research method was checked. Within the tests, there was also obtained a number of interesting results characterizing the material used to build bands and the ranges of changes rolling radii for the tested material were specified.

Studies examining the effect of operator experience on the accuracy of static guided implant surgery have used postoperative computed tomography (CT) images to measure the error, with inconsistent results. The purpose of this study was to try to clarify this issue by using a measurement method based on the postoperative optical scan. Thirty dentists were divided into an experienced group and an inexperienced group. On a partially edentulous mandibular model in the manikin head, each dentist placed three implants via the stereolithographic (SLA) surgical guide. The implant positions were identified by a desktop scanner and compared with the planned positions using a metrology software program. No statistically significant differences were observed for any of the measured positional and angular deviations of the three implant sites between experienced and inexperienced operators (p &gt, 0.01). All the mean values of deviations of the inexperienced group, except the depth deviation, were less than the experienced group. Implants inserted by dentists under 40 years old had significantly better accuracy than senior doctors in the global deviation at implant apex (p = 0.006). Within the limits of this study, we concluded that operator experience is not a critical factor in achieving the accuracy of guided implant surgery via the tooth-supported SLA surgical guide. Large deviations could occur even with the aid of the SLA surgical guide, and care must be taken to avoid errors for both experienced and inexperienced operators.

Precision and ultra-precision machining technology rely mainly on the machine tools&rsquo, accuracy. To improve it, the measurement, calculation, prediction and control of geometric errors are critical. The traditional measurement methods have lower precision because of ignoring small angle errors. To obtain complete geometric errors of multi-axis machine tools, this paper proposes a new method of coupling and decoupling measurement. Specifically, we used a laser interferometer and dial indicators to measure 36 items of complete geometric errors of multi-axis machine tools. A homogeneous transformation matrix (HTM) was applied to model the error transfer route. The transfer law of complete errors for each machining point was explored and derived. Furthermore, we selected and calculated integrated errors of 36 machining points. Finally, we proved the correctness of the method by comparing the measurement result of a ball bar test and coupling and decoupling measurement of geometric errors. We found that items of small geometric angle errors have a greater impact on machining accuracy than those of geometric displacement errors. Complete geometric errors measured via the coupling and decoupling measurement method can evaluate integrated errors more precisely and comprehensively.

Liquid entrainment in a flooded evaporator has an important impact on the performance and safety of a water-cooled centrifugal chiller. In this paper, two methods for measuring the liquid entrainment factor in the evaporator of a centrifugal chiller based on energy balance are proposed. Method 1 involves only the heat exchange capacity of the evaporator and Method 2 involves both evaporator and condenser. The applicable conditions of the methods are discussed. Experimental measurements on the flooded evaporator of a single-stage water-cooled centrifugal chiller with refrigerant R134a show that, for a system with good thermal balance, there is little difference in the entrainment factor values obtained by the two methods. Method 2 was found to have slightly higher measurement accuracy, compared to Method 1. The uncertainty propagation analysis shows that for Method 2, the inlet and outlet water temperatures of the evaporator and condenser, motor input power, motor efficiency, transmission power loss and compressor suction and discharge temperatures are important factors. The experimental results show that the variation of the evaporator entrainment factor with refrigerant charge amount is different for different cooling capacity. At 700 and 800 refrigeration ton (RT), the entrainment factor of the test evaporator increases with the increase of refrigerant charge and the growth rate gradually accelerates. For the chiller tested, when the entrainment factor reaches 0.89% and 1.02%, respectively, at 700 ton and 800 ton, the rapid increase of the entrainment factor leads to a significant decrease in the coefficient of performance (COP) during the charging process. Based on the analysis of the experimental results, it is recommended that the maximum entrainment factor for efficient operation of the centrifugal chiller should be controlled within 1%.

Nonlinear acoustic damping is a key nonlinearity in miniature loudspeakers when the air velocity is at a high amplitude. Measurement of nonlinear acoustic damping is beneficial for predicting and analyzing the performance of miniature loudspeakers. However, the general measuring methods for acoustic impedance, such as the standing-wave tube method or the impedance tube method, are not applicable in this scenario because the nonlinear acoustic damping in miniature loudspeakers is coupled with other system nonlinearities. In this study, a measurement method based on nonlinear system identification was constructed to address this issue. The nonlinear acoustic damping was first theoretically analyzed and then coupled in an equivalent circuit model (ECM) to describe the full dynamics of miniature loudspeakers. Based on the ECM model, the nonlinear acoustic damping was identified using measured electrical data and compared with theoretical calculations. The satisfactory agreement between the identification and theoretical calculations confirms the validity of the proposed identification method.

Background: In the literature there are divergent results as to the native MPFL length change pattern. The reason for such divergent results may be the heterogeneity of design of studies analyzing MPFL isometry. The hypothesis of this review was that studies assessing MPFL length change pattern are highly heterogenous. The aim was to present a state-of-the-art review of sources of this heterogeneity. Materials and Methods: A total of 816 records were identified through the initial search of MEDLINE and Scopus databases. After eligibility assessment, 10 original articles and five reviews were included. In the included studies, the following 15 potential sources of heterogeneity were assessed: number of patients/cadavers, age, males to females ratio (demographics), identification of measured fibers, measurement method, measurement precision, quadriceps muscle activity, iliotibial band activity, hamstrings activity (study design), patellar height, trochlear or patellar dysplasia, femoral anteversion, mechanical axis of the limb, tibial tubercle–trochlear groove distance, and condylar anteroposterior dimensions (morphology). Each variable was graded in every included article with 1 point if reported precisely and not introducing bias; or with 0 points if reported not precisely, introducing bias, or not reported at all. Results: Within original articles, the highest achieved score was 10 out of 15 possible points with mean score of 6.7, SD = 2.37, and minimum score of just 3 out of 15 points. In the demographics section, mean score was 2.4, SD = 0.8 (80% of maximum possible score of 3); in the study design section it was 3.1, SD = 1.87 (52% of maximum possible score of 6); and in the morphology section it was 1.5, SD = 1.43 (25% of maximum possible score of 6). Conclusions: There is high heterogeneity and incomplete reporting of potential sources of bias in studies assessing native MPFL length change pattern. Future investigators should be aware of the presented factors and their potential impact on MPFL isometry. All methodologic factors should be meticulously reported. Detailed description of demographic data is already a standard; however, authors should more extensively report variables concerning study design and morphology of patients’ patellofemoral joint. Furthermore, future studies should try to meticulously simulate the real-life working environment of MPFL and ensure usage of proper measurement methods.

The development of biofilms and the related changes in porous media in the subsurface cannot be directly observed and evaluated. The primary reason that the mechanism of biofilm clogging in porous media cannot be clearly demonstrated is due to the opacity and structural complexity of three-dimensional pore space. Interest in exploring methods to overcome this limitation has been increasing. In the first part of this review, we introduce the underlying characteristics of biofilm in porous media. Then, we summarize two approaches, non-invasive measurement methods and mathematical simulation strategies, for studying fluid–biofilm–porous medium interaction with spatiotemporal resolution. We also discuss the advantages and limitations of these approaches. Lastly, we provide a perspective on opportunities for in situ monitoring at the field site.

(1) Background: Occlusal vertical dimension (OVD) in the optimal maxillo&ndash, mandibular relationship is an important parameter to establish when complex dental rehabilitation has to be done. The optimal method to measure OVD is still a challenge in everyday practice. The aim of the present study was to test the reliability of the correlation between OVD and some anthropometric and cephalometric methods described in the literature. The validity of OVD registration using a facial scanner was also assessed. (2) Materials and Methods: 150 dentate participants, aged 20&ndash, 25 years, were randomly selected using sealed envelopes. Anthropometric measurements between specific standard points were performed: Subnasion&ndash, Prementon (Sn&ndash, PM) and Subnasion&ndash, Gnation (Sn&ndash, Gn) in maximum intercuspation and in the rest mandibular position, right and left pupil to the corresponding chelion. The cephalometric measurements registered were the lower facial angle and the angle between mandibular and Frankfurt planes. The distance Sn&ndash, Gn in maximum intercuspation was compared to all other parameters. Facial scanning, with a mobile phone and installed dedicated application, was performed on ten subjects, randomly selected using the same method among the participants, and the obtained 3D files were analyzed. The digital measurements were compared, for validity, to the clinical measurements. Pearson&rsquo, s correlation coefficient was used, for comparing clinical Sn&ndash, Gn in maximum intercuspation position to the other parameters. (3) Results: A strong agreement between all measured anthropometric parameters of the facial scan and clinical contact measurement method was registered. None of the measured parameters could predict the exact OVD. (4) Conclusions: In the limits of our study, the facial scanning could be used for predictable registration of OVD and the stored digital information could be preserved through life and use for oral rehabilitation. However, if OVD needs to be determined, several measurement methods, including cephalometric measurements, need to be used simultaneously to reach a final decision.

This paper presents the design of a precise &ldquo, ball-column&rdquo, device to efficiently and accurately measure the geometric error terms of both rotary axes of the five-axis machine tool. A geometric error measurement method of spherical contact was proposed based on the influence of the geometric error term from a five-axis machine tool rotating axis on the integrated geometric error of the machine tool. A multiple degree of freedom, step-by-step contact method based on on-machine measure for measuring the spherical center point is proposed, and the solution formula of each geometric error term of the rotating axis is established, respectively. This method can identify 12 geometric errors based on the influence of one rotating axis on another rotating axis after long term operation. The spatial error field of the five-axis machine tool was constructed by analyzing the error law of the two rotating axes of machine tools based on various positions and postures. Finally, after the comparison of the experiment, the results showed that the accuracy of the developed error measurement device reached 91.8% and the detection time was as short as 30&ndash, 40 min.

This article presents the qualitative analyses of the construction of supercapacitor samples. The analyses are based on the suggested thermographic measurements as well as the technique of testing the inherent noise of the investigated element. The indicated assessment methods have been referred to the currently used parameters for the qualitative evaluation of supercapacitors. The approach described in this paper, which introduces additional parameters assessing worn out of supercapacitors, can be included in the so-called non-invasive measurement methods, which allow the assessment of the condition of the sample under test. This article presents the applied measurement stands and verifies of the applicability of measurement methods in relation to the currently used parameters allowing for the qualitative assessment of supercapacitors. The measurement method presented in this article was used to study prototypes of supercapacitors. The measurement results allow for more accurate characterization of the observed element. Conducted tests revealed, at the same time, that one of the proposed evaluation methods, based on measurements of inherent noise of tested supercapacitors, is a method predicting their degradation.

This paper proposes a new high-precision rotor position measurement (RPM) method for permanent magnet spherical motors (PMSMs). In the proposed method, a LED light spot generation module (LSGM) was installed at the top of the rotor shaft. In the LSGM, three LEDs were arranged in a straight line with different distances between them, which were formed as three optical feature points (OFPs). The images of the three OFPs acquired by a high-speed camera were used to calculate the rotor position of PMSMs in the world coordinate frame. An experimental platform was built to verify the effectiveness of the proposed RPM method.