Stereo Configuration Research Articles

New Hydroxyphenylacetic Acids and α-Pyrone Derivative from the Deep-Sea Cold Seep Sediment-Derived Fungus Penicillium corylophilum CS-682.

Two pairs of new enantiomeric hydroxyphenylacetic acid derivatives, (±)-corylophenols A and B ((±)-1 and (±)-2), a new α-pyrone analogue, corylopyrone A (3), and six andrastin-type meroterpenoids (4-9) were isolated and identified from the deep-sea cold-seep sediment-derived fungus Penicillium corylophilum CS-682. Their structures and stereo configurations were determined by detailed spectroscopic analysis of NMR and MS data, chiral HPLC analysis, J-based configuration analysis, and quantum chemical calculations of ECD, specific rotation, and NMR (with DP4+ probability analysis). Compound 3 showed inhibitory activity against some strains of pathogenic bacteria.

Side-Chain Type Ferrocene Macrocycles.

A class of side-chain type ferrocene macrocycles with a radially conjugated system is introduced in this study. The stereo configurations of these ferrocene rings were determined through single-crystal X-ray diffraction analysis. Notably, in the solid state, the ferrocene rings exhibit a distinctive herringbone stacking pattern imposed by a ferrocene-to-ring host-guest interaction. Through UV-vis absorption spectroscopy, electrochemical measurements, and theoretical calculations, valuable insights into the electronic properties of these rings were obtained. In addition, the single crystal of macrocycle A 2 B demonstrates a second-order nonlinear optical response. As a class of organometallic nanorings, this work holds great potential for further exploration in the fields of organometallic chemistry, molecular electronics, and host-guest chemistry.

Image Matching by Bare Homography.

This paper presents Slime, a novel non-deep image matching framework which models the scene as rough local overlapping planes. This intermediate representation sits in-between the local affine approximation of the keypoint patches and the global matching based on both spatial and similarity constraints, providing a progressive pruning of the correspondences, as planes are easier to handle with respect to general scenes. Slime decomposes the images into overlapping regions at different scales and computes loose planar homographies. Planes are mutually extended by compatible matches and the images are split into fixed tiles, with only the best homographies retained for each pair of tiles. Stable matches are identified according to the consensus of the admissible stereo configurations provided by pairwise homographies. Within tiles, the rough planes are then merged according to their overlap in terms of matches and further consistent correspondences are extracted. The whole process only involves homography constraints. As a result, both the coverage and the stability of correct matches over the scene are amplified, together with the ability to spot matches in challenging scenes, allowing traditional hybrid matching pipelines to make up lost ground against recent end-to-end deep matching methods. In addition, the paper gives a thorough comparative analysis of recent state-of-the-art in image matching represented by end-to-end deep networks and hybrid pipelines. The evaluation considers both planar and non-planar scenes, taking into account critical and challenging scenarios including abrupt temporal image changes and strong variations in relative image rotations. According to this analysis, although the impressive progress done in this field, there is still a wide room for improvements to be investigated in future research.

Research on the Application of Deep Learning Algorithm of Artificial Intelligence to 3D Clothing Design in Computerized Virtual Reality Environment

Abstract In this paper, point cloud data is used to construct a human body model, which in turn forms the transformation process of the human body. The corner point detection method is used to decompose the user-input two-dimensional garment shape contour lines, resulting in two types of data lines: shape lines and cross lines. Furthermore, the stereo configuration of the three-dimensional virtual garment is automatically generated using the void volume modeling method and displayed in real-time. The real graphic effect of 3D style is also studied by applying lighting and material processing methods. And take the actual case as the starting point to complete research on the use of 3D clothing design. After analysis, it can be seen that the standard deviation of point cloud data measuring human body parts is small, and the average errors of thickness, circumference, and volume are 1.21%, 2.64%, and 0.053%, respectively. The experimental study designed four garment models with the highest chest fit in terms of T-shirt styles’ fit measurement.

Volume changes measurement of elastomers using 3D DIC

The presented research aims at measuring the volume changes of elastomers using digital image correlation (DIC) in the 3D configuration (stereo DIC). The deformation measurement method in stereo configuration was applied during the mechanical testing of two types of test specimens (dumbbells, cylinders) in uniaxial tension. In this configuration, two cameras were used. The test specimens were measured up to a specified strain value, and the measured data were used to obtain the strain dependence of Poisson’s ratio and the bulk modulus, which are crucial for hyperelastic models. The measurement results reveal that the stereo DIC method provides relatively less scattered data in the low-strain regions for dumbbell-shaped test specimens and is suitable for measuring various test specimen shapes.

Daphnane-type diterpenoids from Stellera chamaejasme L. and their inhibitory activity against hepatocellular carcinoma cells

Daphnane-type diterpenoids, which are scarce in nature, exhibit potent growth-inhibitory activities against various cancer cells. To identify more daphnane-type diterpenoids, the phytochemical components in the root extracts of Stellera chamaejasme L. were analysed in this study using the Global Natural Products Social platform and the MolNetEnhancer tool. Three undescribed 1α-alkyldaphnane-type diterpenoids (1–3; named stelleradaphnanes A–C) and 15 known analogues were isolated and characterised. The structures of these compounds were determined using ultraviolet and nuclear magnetic resonance spectroscopy. The stereo configurations of the compounds were determined using electronic circular dichroism. Next, the growth-inhibitory activities of isolated compounds against HepG2 and Hep3B cells were examined. Compound 3 exhibited potent growth-inhibitory activities against HepG2 and Hep3B cells with half-maximal inhibitory concentration values of 9.73 and 15.97 μM, respectively. Morphological and staining analyses suggested that compound 3 induced apoptosis in HepG2 and Hep3B cells.

Effects of molecular weight, stereo configuration of PLA, and processing on the dispersion of multiwalled carbon nanotubes and properties of corresponding nanocomposites

AbstractMultiwalled carbon nanotubes (MWCNTs) were dispersed and distributed via a co‐rotating twin‐screw extruder (TSE) in high (h)‐ and low (l)‐molecular‐weight amorphous and semicrystalline polylactides (PLAs) (aPLA and scPLA, respectively). Effects of PLA molecular weight and D‐lactic acid equivalents content (D‐content), as well as processing parameters, were examined on the MWCNT dispersion quality in PLA. The effectiveness of the MWCNT dispersion in various PLA matrices was investigated using scanning electron microscopy (SEM) and small‐amplitude oscillatory and transient shear flow rheometry in the molten state. The results showed a better dispersion of MWCNTs in the low‐molecular‐weight PLA grades (aPLAl and scPLAl). In addition, better MWCNT dispersion was observed in aPLA grades when processed at a higher temperature of 190°C than at 150°C. At 150°C, while MWCNT bundles in aPLAl could be broken down, a good dispersion could not be achieved in aPLAh due to the lower molecular mobility at such a temperature. The electrical conductivity of the samples was also shown to increase as the MWCNT dispersion was improved. The existence of crystallites in scPLA‐based nanocomposites, however, disrupted the connectivity of the MWCNTs and decreased the final electrical conductivity. The lower molecular weight aPLAl prepared at 190°C showed the highest electrical conductivity (~10−5 S/m) at a low loading of 0.5 wt.% MWCNTs.

Variable Baseline and Flexible Configuration Stereo Vision Using Two Aerial Robots.

In this work, a new method for aerial robot remote sensing using stereo vision is proposed. A variable baseline and flexible configuration stereo setup is achieved by separating the left camera and right camera on two separate quadrotor aerial robots. Monocular cameras, one on each aerial robot, are used as a stereo pair, allowing independent adjustment of the pose of the stereo pair. In contrast to conventional stereo vision where two cameras are fixed, having a flexible configuration system allows a large degree of independence in changing the configuration in accordance with various kinds of applications. Larger baselines can be used for stereo vision of farther away targets while using a vertical stereo configuration in tasks where there would be a loss of horizontal overlap caused by a lack of suitable horizontal configuration. Additionally, a method for the practical use of variable baseline stereo vision is introduced, combining multiple point clouds from multiple stereo baselines. Issues from using an inappropriate baseline, such as estimation error induced by insufficient baseline, and occlusions from using too large a baseline can be avoided with this solution.

Convex Vision-Based Negative Obstacle Detection Framework for Autonomous Vehicles

This study investigates the convex optimization frameworks for accurate and fast negative obstacle detection as well as depth estimations that are vital for real-time, superior autonomous vehicle operations. A convex framework is proposed in conjunction with a unique stereo perception approach to manage the complex nature of such invisible obstacles. The proposed stereo configuration incorporates an alignment that displaces the cameras along a vertical baseline to extract useful information pertaining to negative obstacle features for various illustrative terrain settings. The convex framework exploits these properties to evaluate depth jumps in the disparity space image and perform geometrical analysis of potential occlusion regions. The corresponding convex formulations are based on linear matrix inequalities to detect sudden disparity, angle profile, and intensity variations for potential negative obstacles and to estimate the internal depth of the detected obstacles. Experimental results demonstrate that consecutive processes can be structured in a convex framework to efficiently identify negative obstacle attributes at a range of distances for texture varying environments, providing a vital extension to real-time vehicular system implementations with superior detection rates.

Omnidirectional Stereo Vision Study from Vertical and Horizontal Stereo Configuration

In stereo vision, an omnidirectional camera has high distortion compared to a standard camera, so the camera calibration is very decisive in its stereo matching. In this study, we will perform stereo matching for an omnidirectional camera with vertical and horizontal configuration so that the result of the image's depth has a 360-degree field of view by transforming the image using a calibration-based method. The result is that by using a vertical camera configuration, the image can be stereo matched directly, but by configuring a horizontal image, it is necessary to carry out a different stereo-matching process in each direction. Stereo matching with the semi-global matching method has better image results than block matching with more image objects detectable by the semi-global block matching method with a maximum disparity value of 32 pixels and with a window size of 21 pixels.

The Cylindrical Drift Chamber of the MEG II experiment

The MEG experiment at the Paul Scherrer Institut (PSI) represents the state of the art in the search for the charged Lepton Flavor Violating μ+→e+γ decay, setting the most stringent upper limit on the BR (μ+→e+γ)≤4.2×10−13 (90% C.L.). An upgrade of MEG, MEG II, was designed, commissioned and recently started the physics data taking. Its goal is to reach a sensitivity level of 6×10−14. In order to reconstruct the positron momentum vector a Cylindrical Drift CHamber (CDCH) with unprecedented peculiarities was built, featuring angular and momentum resolutions at the 6.5 mrad and 100 keV/c level. The CDCH is a 2-meter long, 60 cm in diameter, low-mass, single volume detector with high granularity: 9 layers of 192 drift cells, few mm wide, defined by ∼12000 wires in a stereo configuration for longitudinal hit localization. The filling gas mixture is Helium:Isobutane 90:10. The total radiation length is 1.5×10−3 X0, thus minimizing the Multiple Coulomb Scattering and allowing for a single-hit resolution <120μm. After the assembly at INFN Pisa, the CDCH was transported to PSI and integrated into the MEG II experimental apparatus since 2018. The commissioning phase lasted for the past three years until the operational stability was reached in 2020. The analysis software is continuously developing and the tuning of the reconstruction algorithms is one of the main activities. The latest updates on the positron momentum vector resolutions and tracking efficiency are presented.

Biological Effects and Molecular Mechanisms of Platelet-Rich Plasma on Periodontal Bone Regeneration

Objective: The study investigated the biological effects and molecular mechanisms of platelet-rich plasma (PRP) on periodontal bone regeneration. Methods: Electronic and manual searches were searched up to 1 October 2022 in the following databases: Pubmed, Scopus, Cochrane Library and Embase. [Platelet rich plasma or platelet or growth factors] and [periodontal] or [bone regeneration or bone defect or bone reconstruction] were used for searching. This study reviewed and analyzed published papers associated with PRP and periodontal bone defect restoration or bone regeneration or bone reconstruction. Results: Different growth factors exhibited varied biological characteristics and function. In-vitro studies, animal experiments and clinical studies confirmed that PRP displayed assorted role in periodontal bone defects repair. The growth factors secreted from PRP can promote new bone formation, soft tissue regeneration and wound healing. The fiber three-dimensional structure in PRP is conducive to the growth and migration of cells and provides strong support for the regeneration of periodontal soft and hard tissues. The anti-inflammatory characteristics of PRP are also closely related to the repair of periodontal bone defects. Conclusion: PRP played an important biological effect on periodontal bone regeneration. The mechanism is closely related to PRP promoting the growth, proliferation, differentiation and migration of periodontal ligament cells and osteoblasts, and the fiber stereo configuration of PRP and the anti-inflammatory effect of leukocytes.

DyStSLAM: an efficient stereo vision SLAM system in dynamic environment

Simultaneous localization and mapping (SLAM) is the basis for many robotic applications. Most SLAM algorithms are based on the assumption that the scene is static. In real-world applications, moving objects are inevitable, which will greatly impact the ego-pose estimation accuracy. This paper presents DyStSLAM, a visual SLAM system with a stereo configuration that can efficiently identify moving objects and accomplish dynamic data association. First of all, DyStSLAM extracts feature points, estimates the disparity map, and performs instance segmentation simultaneously. Then, the obtained results are combined to estimate the motion confidence and discriminate between moving objects and static ones. A confidence based matching algorithm is proposed to associate dynamic objects and estimate the pose of each moving object. At the same time, static objects are used to estimate the pose of the camera. Finally, after nonlinear optimization, a sparse point cloud map of both static background and dynamic objects is constructed. Compared with ORB-SLAM2, the proposed method outperforms by 31% for absolute trajectory error on the KITTI dataset.

Comparison of recording studio control room operational response measurements for single, stereo, and immersive audio monitor configurations

Audio monitoring in recording studio control rooms has evolved continuously since the beginning of multitrack systems. In recent years, control rooms have adapted to using multiple audio monitors (loudspeakers) needed for the immersive audio experience. The primary technical recommendations for determining the acoustical quality of a control room are given in EBU-TECH-3276 and ITU BS.1116. The results of measuring the Operational Room Response Curve (ORRC) can differ significantly for only one audio monitor operating compared to the two monitors required for stereo. For multichannel immersive audio configurations, there can also be significant differences in the measured ORRC. A recent immersive system, known as Dolby Atmos, follows the Dolby Laboratories recommendations which generally comply with the EBU/ITU specifications. The goal of this research is to analyze and compare the measurements of the ORRC per the EBU/ITU/Dolby standards for various audio monitor configurations in a control room. These include individual monitors operating alone, two monitors in a stereo configuration operating at the same time, and combinations of monitors in the multichannel immersive audio system. The impact of the coupled system of room acoustics and multiple loudspeakers on the decision quality for the studio user will be addressed.

Commissioning and preliminary performance of the MEG II drift chamber

In the quest for Lepton Flavor Violation (LFV) the MEG experiment at the Paul Scherrer Institut (PSI) represents the state of the art in the search for the charged LFV decay μ+→e+γ, setting the most stringent upper limit on the BR(μ+→e+γ)≤4.2×10−13 (90% C.L.). An upgrade of MEG, MEG II, was designed and it recently started the physics data taking, with the aim to reach a sensitivity level of 6×10−14. The Cylindrical Drift CHamber (CDCH) is a key detector in order to improve the e+ angular and momentum resolutions at the 6.5 mrad and 100 keV/c level. The CDCH is a low-mass single volume detector with high granularity: 9 layers of 192 drift cells each, few mm wide, defined by 12000 wires in a stereo configuration for longitudinal hit localization. After the assembly, the CDCH was transported to PSI for the commissioning phase and it has been integrated into the MEG II experimental apparatus since 2018. The operational stability was reached in 2020 and the complete readout electronics was tested for the first time in 2021. A preliminary analysis of 2020–2021 data is presented.

Two new cyclohexylethanol derivatives from the whole plants of Incarvillea delavayi and their inhibition on LPS-induced NO release in BV-2 cells

Delavatones A (4 β , 7 α -dihydroxy-7 β -(13-methylpent-11-one-12-ene)-octahydrobenzofuran, 1) and B (4 β , 7 α -dihydroxy-7 β -(propan-9-one)-octahydrobenzofuran, 2 ), two structurally unique cyclohexylethanol derivatives with a substituted alkyl chain, were isolated from the 90% ethanol extract of the whole plants of Incarvillea delavayi . The structures of delavatones A and B were characterized by the interpretation of 1D and 2D NMR spectroscopic data in combination with NMR chemical shift calculation coupled with DP4+ probability analysis. In an in vitro assay for anti-inflammatory effect, delavatones A and B displayed remarkable suppression on NO production in LPS-induced BV-2 cells at concentrations ranging from 6 μM to 100 μM. • Two new cyclohexylethanols, delavatones A and B, were isolated from I. delavayi . • Delavatones A and B are two rare cyclohexyethanols with an substituted alkyl chain. • The stereo configurations of delavatones A and B was determined by DP4+ computation. • Delavatones A and B remarkably suppressed LPS induced NO release in BV-2 cells.

Fast Direct Stereo Visual SLAM

We propose a novel approach for fast and accurate stereo visual Simultaneous Localization and Mapping (SLAM) independent of feature detection and matching. We extend monocular Direct Sparse Odometry (DSO) to a stereo system by optimizing the scale of the 3D points to minimize photometric error for the stereo configuration, which yields a computationally efficient and robust method compared to conventional stereo matching. We further extend it to a full SLAM system with loop closure to reduce accumulated errors. With the assumption of forward camera motion, we imitate a LiDAR scan using the 3D points obtained from the visual odometry and adapt a LiDAR descriptor for place recognition to facilitate more efficient detection of loop closures. Afterward, we estimate the relative pose using direct alignment by minimizing the photometric error for potential loop closures. Optionally, further improvement over direct alignment is achieved by using the Iterative Closest Point (ICP) algorithm. Lastly, we optimize a pose graph to improve SLAM accuracy globally. By avoiding feature detection or matching in our SLAM system, we ensure high computational efficiency and robustness. Thorough experimental validations on public datasets demonstrate its effectiveness compared to the state-of-the-art approaches.

Determining the stereo configuration of carbonyl sulfide dimers using Coulomb-explosion imaging

A four-body coincident measurement of carbonyl sulfide dimers is conducted using a femtosecond laser-induced Coulomb explosion. Sequential and concerted processes that occur during the Coulomb explosion are distinguished. Four isomers of carbonyl sulfide dimer are resolved, and their structures are retrieved from the measured coincident momenta of the fragment ions generated in the concerted process, with the help of a classical trajectory simulation. As a result of our study, we can resolve the isomers of a weakly bound molecular cluster and determine their stereo configuration by using the Coulomb explosion. There is also the potential in femtosecond time-resolved imaging for structural evolution of molecular complexes in dissociation.

A Comparative Evaluation of a Single and Stereo Lighthouse Systems for 3-D Estimation

The lighthouse localization system has recently been developed and used for localization in virtual reality (VR). Not only for VR but also for a general indoor positioning systems (IPSs) it has several advantages over existing methods, including low cost, wide detection area, and easy setup. Here, we adopt the stereo configuration of a lighthouse for improved sensing performance and propose a novel calibration method for stereo configuration. For the stereo calibration, the exact positions of sufficient corresponding points in two sensor coordinates need to be determined. A printed checkerboard is widely used for stereo camera systems because it is easy to construct and its accuracy is guaranteed owing to its printing accuracy. However, in the case of the lighthouse system, it is very difficult or impossible to construct a highly accurate calibration board similar to the checkerboard mainly because of manufacturing errors. In this study, we use a receiver sensor and a two-axis linear stage equipped with micrometers. By moving predetermined distances along the x and y directions on the linear stage, we can obtain multiple-point information with high accuracy, which can then be used for the stereo calibration of two lighthouses. In this paper, the calibration and pose estimation procedures are described in detail, and the pose estimation result of the perspective-n-points method is compared with that of the triangulation method. Finally, the pose estimation accuracy of the proposed system is compared with that of a commercial system that is widely used for highly accurate medical applications.

Stereoscopic high-speed imaging of iron microexplosions and nanoparticle-release.

In this work, the combustion behavior of seeded iron particles (d50 = 70 µm) in a laminar diffusion flame was studied in a modified Mckenna flat-flame burner. Two high speed cameras in stereo configuration allowed 3D position and 3D velocity measurements of burning iron particles as well as 3D evaluation of particle microexplosions. Microexplosive processes are important since it can affect both combustion stability and formation of product components. The observed microexplosions happened before particle extinction resulting in change of trajectories, velocities, radiation intensities and fragmentation into smaller particles. It was observed for the first time that fragments of these microexplosions tend to produce planar structures. A frequent release phenomenon was observed during the iron particle combustion using magnified thermal radiation imaging and high-speed shadowgraphy. This release phenomenon was indirectly confirmed with scanning electron microscopy of combust products, revealing multiple cracked particle shells and hollow structures. Black body radiation characteristics was observed indicating the release being in condensed phase and emission spectroscopy identified FeO as intermediate species during combustion. The observed release is believed to mainly consist of iron-oxide nanoparticles formed in the homogenous reaction between vapor iron and oxidizers.