Distance Mismatch Research Articles

Toward physically realistic vision in teleoperation: A user study with light‐field head mounted display and 6‐DoF head motion

AbstractBesides haptics, the visual channel provides the most essential feedback to the operator in teleoperation setups. For optimal performance, the view on the remote scene must provide 3D information, be sharp, and of high resolution. Head‐mounted displays (HMD) are applied to improve the immersion of the operator into the remote environment. Still, so far, no near‐eye display technology was available that provides a natural view on objects within the typical manipulation distance (up to 1.2 m). The main limitation is a mismatch of the 3D distance and the focal distance of the visualized objects (vergence‐accommodation conflict) in displays with fixed focal distance. This conflict potentially leads to eye strain after extended use. Here, we apply a light‐field HMD providing close‐to‐continuous depth information to the user, thus avoiding the vergence‐accommodation conflict. Furthermore, we apply a time‐of‐flight sensor to generate a 2.5D environment model. The displayed content is processed with image‐based rendering allowing a 6 degree‐of‐freedom head motion in the visualized scene. The main objective of the presented study is evaluating the effects of view perspective and light‐field on performance and workload in a teleoperation setup. The reduction of visual effort for the user is confirmed in an abstract depth‐matching task.

Resolving the geometric structure of trastuzumab by mobility capillary electrophoresis and native mass spectrometry

Available online Immunoglobulins G (IgGs) are Y-shaped globular proteins, however, their high flexibility and heterogeneity pose great challenges to their structure and conformation determinations. Geometric structure of IgG closely correlates to its biofunctions, such as the antibody escape of HIV (human immunodeficiency virus) could attribute to the distance mismatch between the ends of two Fab arms (antigen-binding sites) and envelope glycoprotein spikes on virion surface. Herein, we report the first use of mobility capillary electrophoresis (MCE) and native mass spectrometry (nMS) to resolve the internal geometric structure and conformation of an IgG (trastuzumab) in solution phase. After proteolysis, the ellipsoid dimensions of IgG and its subunits were measured by MCE-nMS experiments. IgG was then reconstructed, in which the sizes and relative positions of these three subunits in three-dimensional space were characterized. It was found that the two Fab arms have an angle of ∼102.1° and a distance of ∼11.0 nm between the two antigen-binding sites under native condition, and the Fc arm was tilted ∼ 16.0° towards one of the Fab arms. Fc was not on the plane of Fab-Fab, but has an angle of no larger than 103.1°. Under acidic environment (pH 3.0), each subunit of the IgG would unfold into larger dimensions, and the angles between these subunits also change. With great potential for tumor imaging and therapy, the structure of F(ab′)2 fragments was also measured and validated by molecular dynamic simulation. It was found that the electrostatic force among these three subunits and steric hindrance stemming from Fc help maintaining the angle between two Fab arms.

First principles study of B7N5 as a high capacity electrode material for K-ion batteries.

Potassium-ion batteries (KIBs) are considered a promising candidate for energy storage owing to their low cost and similar "rocking chair" mechanism to lithium-ion batteries. However, there is a great lack of suitable and high working performance electrode materials for KIBs. Herein, first principles calculations based on density functional theory (DFT) are applied to evaluate the potential of the B7N5 monolayer as an anode material for KIBs. It is found that B7N5 shows negative adsorption energies for Li/Na/K on its surface. Besides, the B7N5 monolayer can effectively achieve double-layer adsorption for K atoms on both sides of the monolayer surface, while one-layer adsorption for Li and Na. Thus, B7N5 exhibits an ultra-high theoretical capacity of 1471.5 mA h g-1 for KIBs, which is almost the highest value for the anode materials reported in the literature. And the attractive capacity for KIBs is mainly contributed by the multiple empty electron orbitals of the constituting elements of B7N5 and the small distance mismatch. In addition, K atoms display high diffusivities on B7N5 with low energy barriers of 0.10 eV, and the open circuit voltages of 0.14 V for KIBs are also smaller compared with previous research. It is also shown that after adsorbing K, the semiconducting B7N5 monolayer is transformed to a metallic state with good conductivity. Furthermore, despite the large size of K+, the maximum change in the lattice constant of B7N5 is only 1.32%, indicating structural stability and ensuring good cycling stability for KIBs. The above-mentioned results suggest that B7N5 is a potential anode material for KIBs.

Radiological and clinical outcomes of midline lumbar fusion on sagittal lumbar-pelvic parameters for degenerative lumbar diseases.

Improving the sagittal lumbar-pelvic parameters after fusion surgery is important for improving clinical outcomes. The impact of midline lumbar fusion (MIDLF) on sagittal lumbar-pelvic alignment for the management of degenerative lumbar diseases is still unknown. To analyze the effects of short-segment MIDLF and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) on sagittal lumbar-pelvic parameters. We retrospectively analyzed 63 patients with degenerative lumbar diseases who underwent single-segment MIDLF or MIS-TLIF. The imaging data of patients were collected before surgery and at the final follow-up. The radiological sagittal parameters included the lumbar lordosis (LL), lower LL, L4 slope (L4S), L5 slope (L5S), L5 incidence (L5I), L1 axis and S1 distance (LASD), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and PI-LL mismatch (PI-LL). Additionally, the clinical outcomes, including lower back and leg pain visual analog scale (VAS) and Oswestry disability index (ODI) scores, were also analyzed. In both groups, LL and Lower LL significantly increased, while L5I and LASD significantly decreased at the final follow-up compared to that recorded prior to operation (P < 0.05). In the MIDLF group, L4S significantly decreased compared to that recorded prior to operation (P < 0.05), while the mean SS significantly increased and the PT significantly decreased compared to that recorded prior to operation (P < 0.05). In the MIS-TLIF group, SS slightly increased and the mean PT value decreased compared to that recorded prior to operation, but without a statistically significant difference (P > 0.05). However, the PI-LL in both groups was significantly reduced compared to that recorded prior to operation (P < 0.05). There was no significant difference in the sagittal lumbar-pelvic parameters between the two groups prior to operation and at the final follow-up (P > 0.05). In addition, the change in sagittal lumbar-pelvic parameters did not differ significantly, except for ΔLASD within the two groups (P > 0.05). The mean lower back and leg pain VAS and ODI scores in both groups were significantly improved three months after surgery and at the final follow-up. Though the mean ODI score in the MIDLF group three months after surgery was slightly higher than that in the MIS-TLIF group, there was no significant difference between the two groups at the final follow-up. Short-segment MIDLF and MIS-TLIF can equally improve sagittal lumbar parameters such as LL, Lower LL, L5I, and LASD in the treatment of lumbar degenerative diseases. However, MIDLF had a larger impact on pelvic parameters than MIS-TLIF.

Remaining useful life prediction based on transfer multi-stage shrinkage attention temporal convolutional network under variable working conditions

Many data-driven remaining useful life (RUL) prediction methods usually assume that the training and test data are independent and identically distributed. However, the different degradation trends of machines under variable working conditions can lead to problems with disparate distribution of degradation features and difficulties in obtaining the corresponding labels. To address the above problems, this paper proposed a RUL prediction method based on a transfer multi-stage shrinkage attention temporal convolutional network under variable working conditions. Firstly, a shrinkage attention module is designed by using the attention mechanism and shrinkage operation to eliminate the interference of irrelevant information and increase the focus on critical features. Secondly, a multi-stage shrinkage attention temporal convolution block based on a hybrid attention subnetwork and soft thresholding subnetwork is designed to efficiently learn the manifold structure of the input data to capture the degenerate information-rich deep features. Finally, an unsupervised domain adaptation strategy based on representation subspace distance and bases mismatch penalization is proposed to enhance the learning of cross-domain invariant features. The proposed method is experimentally studied on XJTU-SY and FEMTO datasets. The experimental results demonstrate that the effectiveness and accuracy of the proposed method in RUL prediction are higher than other methods.

Comparison of the Clinical Accuracy of Digital and Conventional Dental Implant Impressions.

The aim of this study was to compare the clinical accuracy of digital and conventional dental implant impressions. Two types of implant impressions were made for each case, namely a conventional open-tray impression and a digital implant impression (DII) using a Trios IOS. Master casts were scanned using a D800 laboratory scanner and STL files were retrieved from conventional and digital workflows to be exported for comparison. The distance between center points, angulation, rotation, vertical shift, and surface mismatch of the scan bodies were evaluated and compared between conventional and digital impression techniques. Comparing digital and conventional impression techniques the following factors showed statistically significant differences: distance (73.7±75 μm), angulation (0.42±0.3°), and surface mismatch of scan bodies. The difference in conventional and digital impression techniques as regards to angulation and distance between the implants were associated with distance, angle, and vertical shift differences in scan. The mismatch of the scanned surface of scan bodies was twice higher for the intraoral scanner group. Clinicians should therefore control the implant suprastructures clinically and also using casts (e.g. printed casts) when a digital scan is planned.

Making Metallic Thin Films Atomically Flat

Can we control the flatness of the surface of a thin film down to the level of individual atoms? Can we further make such an ultraflat surface on a wafer scale? For such purposes, the current deposition methods, including molecular beam epitaxy (MBE), atomic layer deposition (ALD) and conventional sputtering methods, are still not adequate. In this article, we introduce a novel thin film deposition technique developed by modifying a simple sputtering method to make atomically flat metallic surfaces and a new way to investigate the structural details of thin films grown at the atomic level. For thin film, heteroepitaxial growth of a crystalline film on a different crystalline substrate is usual, and the lattice mismatch between the crystalline film and the substrate occurring in heteroepitaxy produces many misfits at the interface, which create various defects, including dislocations and grain boundaries that eventually lead to a rough surface and the deterioration of the overall quality of the crystal. The metamorphic growth method utilizing the extended atomic distance mismatch (EADM) helps to achieve successful growth of thin films in spite of a large lattice mismatch by calculating the match for a relatively long period in advance. Having an ultraflat surface for thin films made of metals such as copper has many advantages. Several advantages and possible applications of metal thin films with ultraflat surfaces are introduced.

Intelligent Fault Diagnosis by Fusing Domain Adversarial Training and Maximum Mean Discrepancy via Ensemble Learning

Nowadays, the industrial Internet of Things (IIoT) has been successfully utilized in smart manufacturing. The massive amount of data in IIoT promote the development of deep learning-based health monitoring for industrial equipment. Since monitoring data for mechanical fault diagnosis collected on different working conditions or equipment have domain mismatch, models trained with training data may not work in practical applications. Therefore, it is essential to study fault diagnosis methods with domain adaptation ability. In this article, we propose an intelligent fault diagnosis method based on an improved domain adaptation method. Specifically, two feature extractors concerning feature space distance and domain mismatch are trained using maximum mean discrepancy and domain adversarial training respectively to enhance feature representation. Since separate classifiers are trained for feature extractors, ensemble learning is further utilized to obtain final results. Experimental results indicate that the proposed method is effective and applicable in diagnosing faults with domain mismatch.

Wafer-scale high-quality Ag thin film using a ZnO buffer layer for plasmonic applications

Realizing laterally continuous, ultraflat silver (Ag) single-crystal films is a significant technological challenge. Ag thin film grown on various hetero-substrates has been used in numerous applications, due to its superior electrical and optical properties. To exploit these properties without degradation and apply these films to high-precision patterning, surface plasmonics, and so on, a high-quality thin film having an ultraflat surface and few grain boundaries is needed. A zinc oxide (ZnO) buffer layer can be used to facilitate the growth of a single-crystalline Ag thin film on a sapphire (Al2O3) substrate. ZnO films deposited on Al2O3 substrates have grain boundaries; however, Ag films grown on ZnO are nearly grain-free and close to single-crystalline quality. This can be explained by the exceptionally small extended atomic distance mismatch, of ~0.08%, between Ag and Al2O3, in which the ninth Ag atom and the eighth Al atom are matched in terms of coherence and periodicity. A modified radio frequency sputtering system with a single-crystal Ag target enabled wafer-scale growth of ultraflat, grain-free Ag films. The proposed approach using a ZnO buffer provides a new method for fabricating Ag films with high adhesion, anti-oxidative stability, and superior optical properties, and allows for easy nano-patterning.

Multi-core fiber based coherent transceiver utilizing self-homodyne detection and ICA based channel equalization for optical intra-datacenter interconnects

We have proposed a cost-effective full-duplex datacenter inter-(or intra-) connection transmission scheme based on self-homodyne coherent detection and multi-core fiber. Independent component analysis (ICA) based channel equalization is applied to remove the requirement of training symbols (TSs) for enhancement of spectral efficiency. We validate in a proof-of-concept experiment using polarization division multiplexing (PDM-) 16QAM orthogonal frequency division multiplexing (OFDM) format over 10-km 7-core fiber in full-duplex way. The results show that the performances can below the forward error correction (FEC) threshold of 3.8 × 10−3. In addition, we investigate the effects of several parameters in the proposed scheme, including laser linewidth and distance mismatch. Finally, we experimentally compared the performance of the proposed scheme to that of employing the TSs for channel compensation to quantify the performance penalty resulting from the TSs removal.

Quantitative evaluation of different thresholding methods using automatic reference image creation via PCA

This article proposes a principal component analysis-based automatic approach to generate reference image for evaluating different thresholding techniques. Twenty one thresholding methods have been considered for reference image creation and evaluated using five standard performance indices. Literature suggests a few performance measures, among which F-measure, modified Hausdorff distance, edge mismatch error, relative area error and object level consistency error are popular. However, correlation analysis of these metrics reveal that only F-measure, modified Hausdorff distance and edge mismatch error retain non-redundant information. Thus the best thresholding method can be determined from these three indices for different types of images, automatically. Experimental results demonstrate the potential of different thresholding methods and select the best binary segmentation technique for particular type of image set.

Novel transmitter IQ imbalance compensation algorithm using training symbols in PDM CO-OFDM system

We systematically deduce the optical fiber channel transmission mathematical model with in-phase/quadrature (IQ) imbalance and channel distortion for polarization division multiplexed (PDM) coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. With the analysis of model, we propose two novel algorithms using training symbols, which can well realize channel distortion and IQ imbalance estimation. This study shows the proposed algorithms performed significantly better than the commonly used approaches. We examine the two proposed methods with simulation via analyzing the bit error rate in the case of different optical signal to noise ratio (OSNR), transmission distance and IQ mismatch at 80Gb/s and 100Gb/s.

Taming Mismatches in Inter-agent Distances for the Formation-Motion Control of Second-Order Agents

This paper presents the analysis on the influence of distance mismatches on the standard gradient-based rigid formation control for second-order agents. It is shown that, similar to the first-order case as recently discussed in the literature, these mismatches introduce two undesired group behaviors: A distorted final shape and a steady-state motion of the group formation. We show that such undesired behaviors can be eliminated by combining the standard formation control law with distributed estimators. Finally, we show how the mismatches can be effectively employed as design parameters in order to control a combined translational and rotational motion of the formation.

Robustness issues in double-integrator undirected rigid formation systems

In this paper we consider rigid formation control systems modelled by double integrators (including formation stabilization systems and flocking control systems), with a focus on their robustness property in the presence of distance mismatch. By introducing additional state variables we show the augmented double-integrator distance error system is self-contained, and we prove the exponential stability of the distance error systems via linearization analysis. As a consequence of the exponential stability, the distance error still converges in the presence of small and constant distance mismatches, while additional motions of the resulted formation will occur. We further analyze the rigid motions induced by constant mismatches for both double-integrator formation stabilisation systems and flocking control systems.

On the Role and Compensation of Distance Mismatches in Rigid Formation Control for Second-Order Agents

Abstract: This paper presents a robustness analysis of gradient-based formation control law for second-order agents subjected to distance mismatches or constant disturbances. It is shown that, akin to the first-order case, the existence of these mismatches introduces two undesired group behaviors: a distorted final shape and a stationary group motion. We show that such undesired properties can be compensated by combining the gradient-based rigid formation control law and our proposed distributed estimators.

Auditory perceptual category formation does not require perceptual warping.

Categorical perception occurs when a perceiver's stimulus classifications affect their ability to make fine perceptual discriminations and is the most intensively studied form of category learning. On the basis of categorical perception studies, it has been proposed that category learning proceeds by the deformation of an initially homogeneous perceptual space ("perceptual warping"), so that stimuli within the same category are perceived as more similar to each other (more difficult to tell apart) than stimuli that are the same physical distance apart but that belong to different categories. Here, we present a significant counterexample in which robust category learning occurs without these differential perceptual space deformations. Two artificial categories were defined along the dimension of pitch for a perceptually unfamiliar, multidimensional class of sounds. A group of participants (selected on the basis of their listening abilities) were trained to sort sounds into these two arbitrary categories. Category formation, verified empirically, was accompanied by a heightened sensitivity along the entire pitch range, as indicated by changes in an EEG index of implicit perceptual distance (mismatch negativity), with no significant resemblance to the local perceptual deformations predicted by categorical perception. This demonstrates that robust categories can be initially formed within a continuous perceptual dimension without perceptual warping. We suggest that perceptual category formation is a flexible, multistage process sequentially combining different types of learning mechanisms rather than a single process with a universal set of behavioral and neural correlates.

Linearity analysis of closed-loop capacitive accelerometer due to distance mismatch between plates and the influence of compensation capacitor array

This paper presents mathematical formulae showing that the distance mismatch for an uncentered proof mass in an accelerator sensor does not influence the linearity of the closed-loop accelerometer as a whole. This asymmetry in sensors only introduces an output voltage offset in the readout integrated circuit. Numerical simulation using Matlab/Simulink confirms the mathematical conclusion. The linear response after compensation with a conventional capacitor array is also simulated and analyzed. Results show that there is a loss in linearity. Similar results hold not only for the continuous-time architecture, but also for a time-divided architecture. A readout integrated circuit with a time-divided architecture is designed and fabricated using a 0.35 μm HV CMOS process. An accelerometer composed of a microelectromechanical system sensor with severe built-in distance mismatch and the designed readout integrated circuit is tested. Test results show that the nonlinearity of such accelerometer is within 0.3%.

Speaker Distance Detection Using a Single Microphone

A method to detect the distance of a speaker from a single microphone in a room environment is proposed. Several features, related to statistical parameters of speech source excitation signals, are introduced and are shown to depend on the distance between source and receiver. Those features are used to train a pattern recognizer for distance detection. The method is tested using a database of speech recordings in four rooms with different acoustical properties. Performance is shown to be independent of the signal gain and level, but depends on the reverberation time and the characteristics of the room. Overall, the system performs well especially for close distances and for rooms with low reverberation time and it appears to be robust to small distance mismatches. Finally, a listening test is conducted in order to compare the results of the proposed method to the performance of human listeners.

HIGH-SPEED SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY SIGNAL PROCESSING WITH TIME-DOMAIN INTERPOLATION USING GRAPHICS PROCESSING UNIT

Sensitivity and data processing speed are important in spectral domain Optical Coherence Tomography (SD-OCT) system. To get a higher sensitivity, zero-padding interpolation together with linear interpolation is commonly used to re-sample the interference data in SD-OCT, which limits the data processing speed. Recently, a time-domain interpolation for SD-OCT was proposed. By eliminating the huge Fast Fourier Transform Algorithm (FFT) operations, the operation number of the time-domain interpolation is much less than that of the zero-padding interpolation. In this paper, a numerical simulation is performed to evaluate the computational complexity and the interpolation accuracy. More than six times acceleration is obtained. At the same time, the normalized mean square error (NMSE) results show that the time-domain interpolation method with cut-off length L = 21 and L = 31 can improve about 1.7 dB and 2.1 dB when the distance mismatch is 2.4 mm than that of zero-padding interpolation method with padding times M = 4, respectively. Furthermore, this method can be applied the parallel arithmetic processing because only the data in the cut-off window is processed. By using Graphics Processing Unit (GPU) with compute unified device architecture (CUDA) program model, a frame (400 A-lines × 2048 pixels × 12 bits) data can be processed in 6 ms and the processing capability can be achieved 164,000 line/s for 1024-OCT and 71,000 line/s for 2048-OCT when the cut-off length is 21. Thus, a high-sensitivity and ultra-high data processing SD-OCT is realized.

Structural properties of the epitaxial CuCr 0.95Mg 0.05O 2 thin films on c-plane sapphire substrates by pulsed laser deposition

We report an investigation of the structural properties of CuCr 0.95Mg 0.05O 2 films on c-plane sapphire substrates using pulsed laser deposition. The thin films were grown at different temperatures of 500, 600, and 700 °C with an oxygen partial pressure of 10 mTorr. c-axis oriented epitaxial CuCr 0.95Mg 0.05O 2 thin films on c-plane sapphire substrates with an in-plan 30° rotation were obtained. The sixfold rotational symmetry in the pole figures from the (0 1 2) plane indicates that there are two different types of crystal grains in which the a-axes rotate by 60° with respect to each other around the c-axis. The reason for the 30° rotation is assumed to be the presence of the ∼10% mismatch of oxygen distance between the c-plane sapphire substrate and the CuCr 0.95Mg 0.05O 2 on the c-plane. The epitaxial crystallographic relationship between CuCr 0.95Mg 0.05O 2 and Al 2O 3 was (0 0 0 6)CuCrO 2//(0 0 0 3)Al 2O 3 and [1 0 −1 0]CuCrO 2//[1 1 −2 0]Al 2O 3. The presence of twins in the films and the surface morphology were investigated using transmission electron microscopy and scanning electron microscopy, respectively.