Auxiliary Measurement Research Articles

Gain sensitivity of the Mach–Zehnder interferometer by photon subtraction

Abstract The phase sensitivity of a Mach–Zehnder (MZ) interferometer with a two-mode squeezed vacuum (TMSV) probe state is studied. At the initial stage, the TMSV state is deterministically converted into two single-mode squeezed vacuum (SMSV) states, from each of which photons are subtracted via photon-number resolving measurement in auxiliary measurement modes. The new probe state can already demonstrate gain sensitivity of more than 20 dB with input squeezing of 5 dB and follow Heisenberg scaling. The phase sensitivity of the MZ interferometer, estimated by measuring the intensity difference of two measurement-induced continuous variable states, can surpass the ultimate one with SMSV probe states, at least, with squeezing less than 5 dB. In general, the strategy with preliminary subtraction of photons significantly increases the estimate potential of weakly squeezed states as the probe in MZ phase-dependent interferometry; in particular, it is more effective compared to generating highly squeezed TMSV states or SMSV states.

Developing a new interface for Qibla direction application based on MATLAB GUI

In this study, a MATLAB GUI-based interface has been developed that can be integrated with GNSS receivers. Through this interface developed for calculation and querying purposes, Qibla direction application with geodetic precision can be achieved using coordinate information of a corner of the mosque and its facade length, without the need for auxiliary geodetic measurement devices and computational burden. Furthermore, interface allows users to query the Qibla directions in mosques for inspection. It has been found that 2% of the mosques are outside the Qibla direction, 51% are outside the Miqat boundaries, and 8% are within the Haram boundaries.

Research on a Machine Vision-based Blade Measurement Method

A high-precision visual measurement method for the geometric dimensions of oil pump blades is proposed, utilizing an auxiliary measurement mechanism to assist in sub-pixel edge positioning. Based on images of calibration boards, the camera distortion is corrected by partitioning the image into regions and establishing a mapping index between pixel coordinates and real-world coordinates. Under fixed object and image distances, images of the oil pump blades and the contact between the blades and the pump are separately captured. The Canny operator and Sigmoid function are employed to fit the edges, extracting sub-pixel coordinates, which are then mapped to real-world coordinates. Finally, a least squares edge fitting is conducted to compute the dimensional parameters. Experimental results indicate that the use of auxiliary measurement mechanisms effectively enhances the precision of blade measurements, as compared to measurements solely based on oil pump blade images and images of the blade in contact with the pump.

Reconfigurable Intelligent Surface Assisted Target Three-Dimensional Localization with 2-D Radar

Battlefield surveillance radar is usually 2-D radar, which cannot realize target three-dimensional localization, leading to poor resolution for the air target in the elevation dimension. Previous researchers have used the Traditional Height Finder Radar (HFR) or multiple 2-D radar networking to estimate the target three-dimensional location. However, all of them face the problems of high cost, poor real-time performance and high requirement of space–time registration. In this paper, Reconfigurable Intelligent Surfaces (RISs) with low cost are introduced into the 2-D radar to realize the target three-dimensional localization. Taking advantage of the wide beam of 2-D radar in the elevation dimension, several Unmanned Aerial Vehicles (UAVs) carrying RISs are set in the receiving beam to form multiple auxiliary measurement channels. In addition, the traditional 2-D radar measurements combined with the auxiliary channel measurements are used to realize the target three-dimensional localization by solving a nonlinear least square problem with a convex optimization method. For the proposed RIS-assisted target three-dimensional localization problem, the Cramer–Rao Lower Bound (CRLB) is derived to measure the target localization accuracy. Simulation results verify the effectiveness of the proposed 3-D localization method, and the influences of the number, the positions and the site errors of the RISs on the localization accuracy are covered.

Observability analysis and optimization for angles-only navigation of distributed space systems

Angles-only navigation methods are compelling for distributed space systems (DSS) such as swarms and constellations. However, complex dependencies between state observability and system parameters present a challenging design problem. This paper proposes a unified angles-only observability analysis and design framework enabling designers of a DSS to 1) analytically determine whether its orbit state is observable, 2) numerically estimate its expected navigation performance, and 3) intelligently optimize the system to meet navigation requirements. First, a new system measurement topology representation is proposed for which analytic orbit observability can be assessed via a set of graphical conditions. Second, methods for numeric estimation of the achievable state covariance are augmented with auxiliary state variables, dynamics uncertainty, and measurement availability constraints. Third, a system cost function is developed and the topological and numeric methods are placed within a quasi-Newton optimization framework to enable automatic system design. The optimization is applied to a distributed science swarm and a space situational awareness constellation in lunar orbit. Both scenarios converge to a global cost minimum and output designs that achieve user requirements under realistic measurement conditions and constraints. Combined analytic and numeric methods therefore presents a powerful tool for design of angles-only DSS.

Ex-situ deformation measurement system based on dual-reflector

We propose an ex-situ reposition error compensation method to solve the reposition error in the ex-situ state of 2D digital image correlation (2D-DIC) in the long-term deformation of the measurement specimen or under special load deformation. Using the dual-reflector auxiliary measurement system with an included angle of 90 deg, the two sides of the repositioned specimen are mapped into left and right mirrors. The in- and out-of-plane rigid body displacements are compensated via the error compensation method, and the real in-plane displacement of the tested specimen is obtained. The accuracy and practicability of this method are verified by conducting an in-plane rigid body displacement experiment, unloaded specimen reposition experiment, thermal deformation experiment, and finite element analysis. We provide a simple, effective, and high-precision deformation measurement method for 2D-DIC to realize ex-situ measurement.

Photoplethysmography signal quality assessment using attractor reconstruction analysis

The Photoplethysmography (PPG) has already proved its importance as an auxiliary vital signal measurement technique. The PPG is predominantly a quasi-periodic signal for small timescales. This property allows the reconstructing of a phase space and, therefore, the attractor of PPG segments which presents good insights on dynamics of physiological systems. However, the assessment of PPG waveforms is a difficult task due to motion artifacts, biological tissue differences and other sources of noise. In the same direction, protocols for PPG signals acquisition have its development in a slower step. To contribute against this scenario, this work proposes and describes a method using the attractor reconstruction analysis to provide a quality assessment of PPG signals. The method presented good results in classifying into good and bad quality PPG signals segments achieving F1-score of 97%. The method is totally analytical, thus, it is suitable for real-time applications. No training process is required, it is independent of the subject physiology and no calibration is needed.

A precise forest spatial structure investigation using the SLAM+AR technology

IntroductionForest spatial structures are the foundations of the structure and function of forest ecosystems. Quantitative descriptions and analyses of forest spatial structure have recently become common tools for digitalized forest management. Therefore, the accuracy and intelligence of acquiring forest spatial structure information are of great significance.MethodsIn this study, we developed a forest measurement system using a mobile phone. Through this system, the following tree measurements can be achieved: (1) point cloud of tree and chest diameter circle to measure tree diameter at breast height (DBH) and position coordinates of tree by using simultaneous localization and mapping (SLAM) technology, (2) virtual boundary creation of the sample plot, and the auxiliary measurement function of tree with the augmented reality (AR) interactive module, and (3) position coordinates and single-tree volume factor to calculate the spatial structural parameters of the forest (e.g., Mingling degree, Dominance index, Uniform angle index, and Crowdedness index).The system was tested in three 32 x 32 martificial forest plots.ResultsThe average DBH estimations showed BIAS of -0.47 to 0.45 cm and RMSEs of 0.57 to 0.95 cm. Its accuracy level met the requirements of forestry sample surveys. The tree position estimates for the three plots had relatively small RMSEs with 0.17 to 0.22 m on the x-axis and 0.16 to 0.26 m on the y-axis. The spatial structural parameters were as follows: the mingling degree of plot 1 was 0.32, and the overall mixing degree of tree species was low. The trees in plots 2 and 3 were all single species, and the mixing degree of both plots was 0. The dominance index of the three plots was 0.56, 0.51, and 0.51, indicating that the competitive advantage of the whole orest species was not obvious. The uniform angle index of the three plots was 0.55, 0.59, and 0.61, indicating that the positions of trees in the three plots were randomly distributed. The crowdedness index of plot 1 was 1.03, indicating that the degree of aggregation of the trees was low and showed a random distribution trend. The crowdedness index of the other plots were 1.36 and 1.40, indicating that the trees in the plots show a trend of uniform distribution, and the uniformity of plot 3 is higher than that of plot 2, but the overall uniformity is relatively weak.DiscussionThe findings of this study provide support for the optimization of forest structures and improve our conceptual understanding of forest community succession and restoration, in addition to the informatization and precision of forest spatial structure surveys.

Bearing-Based Formation Tracking Control With Time-Varying Velocity Estimation.

This article studies the bearing-based formation tracking control problem of multiple double-integrator agents. A leader-following structure, where the leader moves with the reference dynamics, is adopted. Different from the existing methods, which require complete information of the time-varying reference velocity, in this article, only the time-varying reference orientation information is known by part of the followers and the amplitude of the reference velocity is unknown. To solve the problem, this article proposes a velocity-estimation-based control scheme, which consists of an estimator for estimating the varying rate of the reference orientation, an adaptation law for estimating the amplitude of the reference velocity, and bearing-based control inputs for tracking the leader and achieving the bearing-based formation based on the estimations. Moreover, the scaling formation maneuver can be achieved by using an auxiliary distance measurement. It shows that both the estimation errors and control errors converge to zero under the connectivity of the topology and properties of bearing rigidity. The closed-loop system is analyzed to be semiglobally uniformly asymptotically stable based on the cascaded system theory. Numerical simulations are presented to demonstrate the effectiveness of our method.

Precision spraying using variable time delays and vision-based velocity estimation

Traditionally, precision farm equipment often relies on real-time kinematics and global positioning systems (RTK-GPS) for accurate position and velocity estimates. This approach proved effective and widely adopted in developed regions where RTK-GPS satellite and base station availability and visibility are not limited. However, RTK-GPS signal can be limited in farm areas due to topographic and economic constraints. Thus, this study developed a precision sprayer that estimated the travel velocity locally by tracking the relative motion of plants using a deep-learning-based machine vision system. Sprayer valves were then controlled by variable time delay (VTD) queuing and dynamic filtering. The proposed velocity estimation approach was tested at different velocities and tracking thresholds. The results showed that the velocity estimates agreed with actual measurements with a mean absolute error of 0.036 m/s. Further, testing the targeting algorithm on rows of artificial crops and weeds at different levels of spraying duration and filter size factor (FSF) showed that short spraying duration and small FSF increase overall spraying accuracy. Finally, testing the sprayer using the optimum settings at 0.87 m/s and 1.03 m/s successfully sprayed all targets. Further, only 2% to 7% of non-targets were sprayed at the low and high test velocities, respectively. With these results, this study suggests that vision-based velocity estimation combined with VTD queuing and dynamic filtering can be an accurate and low-cost solution for targeted spraying without using auxiliary velocity measurement systems.

6. Assessment of Robot-assisted Mandibular Contouring Surgery in Comparison with Traditional Surgery: A Prospective, Single-center, Randomized Controlled Trial

PURPOSE: Few clinical studies on robot-assisted surgery (RAS) for mandibular contouring have been reported. The aim of this study was to follow the long-term effectiveness and safety of RAS for craniofacial bone surgery. METHODS: This small-sample, early-phase, prospective, randomized controlled study included patients diagnosed with mandibular deformity requiring mandibular contouring surgery. Patients of both genders aged 18 to 30 years without complicated craniofacial repair defects were enrolled and randomly assigned in a 1:1 ratio by a permuted-block randomized assignments list generated by the study statistician. The primary outcomes were the positioning accuracy and accuracy of the osteotomy plane angle 1 week after surgery. Surgical auxiliary measurement index, patient satisfaction scale, surgical pain scale, perioperative period, and complications at 1 week, 1 month, and 6 months after surgery were also analyzed. RESULTS: One patient was lost to follow-up, resulting in a total of 14 patients in the traditional surgery group and 15 in the robot-assisted group (mean [standard deviation] age, 22.65 [3.60] years). Among the primary outcomes, there was a significant difference in the positioning accuracy (2.91 mm vs 1.65 mm; P < 0.01) and angle accuracy (13.26º vs 4.85º; P < 0.01) between the 2 groups. Secondary outcomes did not significantly differ. CONCLUSION: Compared to traditional surgery, robot-assisted mandibular contouring surgery showed improved precision in bone shaving, as well as higher safety.

Mapping of marine litter on the seafloor using WASSP S3 multibeam echo sounder and Chasing M2 ROV

Marine litter is a growing threat to the marine environment. Mapping of marine litter is becoming increasingly important to detect its potential hotspots and prevent their spread. In this paper, the applicability of the multibeam echo sounder (MBES) WASSP S3 and remotely operated underwater vehicle (ROV) Chasing M2 was tested in the detection and mapping of marine litter on the seafloor within the wider area of the St. Ante Channel (Šibenik, Croatia). Also, the precision assessment of WASSP S3 was tested at different cruising speeds. Results have shown that Chasing M2 can be used effectively for the initial detection of marine debris in shallow waters. However, if the underwater navigation and positioning system and auxiliary measurement scales are not used, the ROV has limited capabilities in deriving morphometric parameters of marine litter on the seafloor. This was determined by comparing the 3D model of a tire which was derived using video photogrammetry captured with ROV and the 3D model of a tire which was produced using a hand-held 3D scanner. Furthermore, the results have shown the WASSP S3 is not suitable for identifying marine litter smaller than 1 m at depths up to 10 m. The MBES WASSP S3 can detect marine litter that has a minimum area of 100 * 100 cm and a height of around 40 cm at depths up to 10 m. The results pointed to the need for caution when choosing an adequate sensor to detect and map marine litter on the seafloor. In addition, MBES interval measurements have shown that WASSP S3 precision is in the centimeter range (&amp;lt;10 cm) at different cruising speeds. The obtained results have helped to establish the guidelines for the integrated use of MBES, ROV, and UAV in the detection of marine litter on the seafloor.

Sampling algorithm for geno- and subtyping of hepatitis B virus using panel of monoclonal antibodies in enzyme immunoassay

Introduction. Previously, a domestic method for determining hepatitis B virus (HBV) genotypes and HBV surface antigen (HBsAg) subtypes in HBsAgpositive blood serum samples with a Monoclonal Antibody Panel (MAB) by enzyme immunoassay (ELISA) was described. In routine laboratory practice, HBsAg detection results are obtained in units of optical density (OD).Purpose. To describe the sampling algorithm for ELISA geno- and subtyping of HBV with the MAB Panel.Materials and methods. We studied 40 blood serum samples with positive results of HBsAg determination. HBV genotypes and HBsAg subtypes were determined using four different MAB conjugates with horseradish peroxidase using the ELISA method described previously.Results. In samples with OD less than 2.0 o. u. and confirmation of HBsAg after a single confirmatory study (n = 19) HBV genotypes/ HBsAg subtypes not established. In samples with an OD above 2.0 o. u. and verification of the presence of the antigen in the standard mode of registration (n = 15), immunoenzymatic geno- and subtyping of HBV was effective in 27 % of cases (4/15); for samples with HBsAg verification carried out in an auxiliary measurement (n = 6) the effectiveness of the technique was 100 %. Using the MAB panel in ELISA, the characteristics of HBV in 10 samples with the presence of HBsAg were studied: HBV genotype D (n = 10), subtypes ayw2 (n = 7), ayw3 (n = 3).Conclusions. For the most effective application of the HBV geno- and subtyping technique using the MAB Panel in ELISA, HBsAg+ samples with OD signals of more than 2.0 o. u. in screening and verification of the presence of an antigen in the auxiliary mode of registration of results should be used.

An evaluation methodology for the circumferential position error of the V-shaped apex of the double-helical gear.

Aiming to achieve an accurate evaluation of the circumferential position error of the V-shaped apex of double-helical gear, the definition of the V-shaped apex of double-helical gear and the evaluation method of the circumferential position error is studied based on the geometric characteristics of double-helical gear and the definition of shape error. First, the definition of the V-shaped apex of double-helical gear based on the helix and its circumferential position error is presented based on the (American Gear Manufacturers Association) AGMA940-A09 standard. Second, based on the basic parameters, the tooth profile characteristics, and the tooth flank forming principle of double-helical gear, the mathematical model of double-helical gear in a Cartesian space coordinate system is established, and the auxiliary tooth flank and auxiliary helix are constructed to generate some auxiliary measurement points. Finally, the auxiliary measurement points are fitted using the least-squares principle to calculate the position of the V-shaped apex of the double-helical gear in the actual meshing condition and its circumferential position error. The simulation and experimental results show that the simulation results verify the feasibility of the method, and the experimental results (the circumferential position error of the V-shaped apex is 0.0187mm) are consistent with the results of the literature [Bohui etal., Metrol. Meas. Technol. 36, 33 (2016)]. This method can effectively realize the accurate evaluation of the double-helical gear V-shaped apex position error, providing some guidance for the design and manufacture of double-helical gear.

Image-Guided Measurement of Radiation Force Induced by Focused Ultrasound Beams.

The radiation force balance (RFB) is a widely used method for measuring acoustic power output of ultrasonic transducers. The reflecting cone target is attractive due to its simplicity and long-term stability, at a reasonable cost. However, accurate measurements using this method depend on the alignment between the ultrasound beam and cone axes, especially for highly focused beams utilized in therapeutic applications. With the advent of dual-mode ultrasound arrays (DMUAs) for imaging and therapy, image-guided measurements of acoustic output using the RFB method can be used to improve measurement accuracy. In this article, we describe an image-guided RFB measurement of focused DMUA beams using a widely used commercial instrument. DMUA imaging is used to optimize the alignment between the acoustic beam and reflecting cone axes. In addition to image-guided alignment, DMUA echo data is used to track the displacement of the cone, which provides an auxiliary measurement of acoustic power. Experimental results using a DMUA prototype with [Formula: see text] shows that 1-2 mm of misalignment can result in 5%-14% error in the measured acoustic power. In addition to the use of B-mode image guidance for improving measurement accuracy, we present preliminary results demonstrating the benefit of displacement tracking using real-time DMUA imaging during the application of (sub)therapeutic focused beams. Displacement tracking provides a direct measurement of the radiation force with high sensitivity and follows the expected dependence on changes in amplitude and duty cycle (DC) of the focused ultrasound (FUS) beam. This could lead to simpler, more reliable methods for measuring acoustic power based on the radiation force principle. Combined with appropriate computational modeling, the direct measurement of acoustic radiation force could lead to reliable dosimetry in situ in emerging applications such as transcranial FUS (tFUS) therapies.

A Highly Stable Physically Unclonable Function Using Algorithm-Based Mismatch Hardening Technique in 28-nm CMOS

Physically unclonable function (PUF) is an emerging security solution for Internet of Things (IoT) devices. However, PUF faces a critical design challenge: responses should remain the same regardless of environmental conditions. This article presents an algorithm-based mismatch hardening technique that provides an effective and efficient solution to stabilizing PUF responses, which could be applied to various PUF circuits. The proposed stabilization technique combines multiple mismatches to achieve high reliability with minimum loss of utility. Moreover, the proposed approach requires only the available digitized PUF responses, avoiding any auxiliary measurement circuit to minimize additional implementation and testing overhead. The PUF test chip implemented in 28-nm CMOS technology shows that the proposed stabilization technique achieves a highly stable performance, lowering the nominal bit error rate (BER) to 0.0016%. It also exhibits excellent reliability with a worst-case BER of 0.16% across 0.7 to 1.2 V and −50 to 125°C, proving to be a promising candidate for security primitive for IoT applications.

An Effective Lightweight Measurement Model to Enable Coal Dust Size Distribution Analysis

This article presents an image segmentation model based on U-Net combined with visual sensing. It is aimed at studying the inherent mechanism of coal dust imagery characteristics and is employed to carry out semantic segmentation of particle images. For the feature maps with more redundant information generated by the conventional method, the parameter quantity of the proposed model can be lessened by Ghost-bottleneck, which substitutes for the original convolution in U-Net. The Ghost-SE bottleneck is introduced in the feature backbone to capture the attention of key feature channels, which is able to improve the learning ability for particle characteristics. Thus, particles with different shapes and sizes are credibly discriminated. Finally, the proposed model is evaluated with the coal dust particle proportion in six dust-producing scenes. The experimental results show that the performance metrics accuracy, recall rate, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$F1$ </tex-math></inline-formula> scores are increased to 0.8732, 0.8434, and 0.8580, respectively, and the mean error <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon $ </tex-math></inline-formula> with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R &lt; 75~\mu \text{m}$ </tex-math></inline-formula> is 3.526% compared with the reference standard. This indicates that introducing modules in the backbone is indeed able to speed up the convergence of the network and improve the accuracy of coal dust particle segmentation. It can be used as an effective auxiliary measurement of coal dust detection for coal mine safety video monitoring.

Beyond one-axis twisting: Simultaneous spin-momentum squeezing

The creation and manipulation of quantum entanglement is central to improving precision measurements. A principal method of generating entanglement for use in atom interferometry is the process of spin squeezing whereupon the states become more sensitive to $SU(2)$ rotations. One possibility to generate this entanglement is provided by one-axis twisting (OAT), where a many-particle entangled state of one degree of freedom is generated by a non-linear Hamiltonian. We introduce a novel method which goes beyond OAT to create squeezing and entanglement across two distinct degrees of freedom. We present our work in the specific physical context of a system consisting of collective atomic energy levels and discrete collective momentum states, but also consider other possible realizations. Our system uses a nonlinear Hamiltonian to generate dynamics in $SU(4)$, thereby creating the opportunity for dynamics not possible in typical $SU(2)$ one-axis twisting. This leads to three axes undergoing twisting due to the two degrees of freedom and their entanglement, with the resulting potential for a more rich context of quantum entanglement. The states prepared in this system are potentially more versatile for use in multi-parameter or auxiliary measurement schemes than those prepared by standard spin squeezing.

In-Flight Alignment of Integrated SINS/GPS/Polarization/Geomagnetic Navigation System Based on Federal UKF.

As a common integrated navigation system, the strapdown inertial navigation system (SINS)/global positioning system (GPS) can estimate velocity and position errors well. Many auxiliary attitude measurement systems can be used to improve the accuracy of attitude angle errors. In this paper, the in-flight alignment problem of the integrated SINS/GPS/Polarization/Geomagnetic navigation system is discussed. Firstly, the SINS/Geomagnetic subsystem is constructed to improve the estimation accuracy of horizontal attitude angles. Secondly, the polarization sensor is used to improve the estimation accuracy of heading angle. Then, a federal unscented Kalman filter (FUKF) with non-reset structure is applied to fuse the navigation data. Finally, simulation results for the integrated navigation system are provided based on experimental data. It can be shown that the proposed approach can improve not only the speed and position, but also the attitude error effectively.

Flexible field calibration of transmitter location and orientation in accurate large-scale positioning system

An accurate large-scale positioning system is a high-precision distributed large-scale dimensional metrology system that is widely used in smart manufacturing and assembly applications. The system comprises multiple transmitters with locations and orientations that are typically calibrated based on auxiliary measurement equipment. However, the calibration method is complicated and time consuming. We propose a rapid and flexible calibration method based on the highly precise three-dimensional coordinate control network established by a calibration bar with an accuracy of ± 0.005 mm, including both estimation and optimization algorithms. Exploratory experiments were performed to validate the feasibility of the proposed calibration method. The results demonstrate that the proposed calibration method enables the repeated measurement errors to be maintained at <0.05 mm in X and Y and <0.04 mm in Z. The standard deviation after calibration was 0.18 mm in comparison with the laser tracker.