Ar System Research Articles

Application of single-image camera calibration for ultrasound augmented laparoscopic visualization.

Accurate calibration of laparoscopic cameras is essential for enabling many surgical visualization and navigation technologies such as the ultrasound-augmented visualization system that we have developed for laparoscopic surgery. In addition to accuracy and robustness, there is a practical need for a fast and easy camera calibration method that can be performed on demand in the operating room (OR). Conventional camera calibration methods are not suitable for the OR use because they are lengthy and tedious. They require acquisition of multiple images of a target pattern in its entirety to produce satisfactory result. In this work, we evaluated the performance of a single-image camera calibration tool (rdCalib; Percieve3D, Coimbra, Portugal) featuring automatic detection of corner points in the image, whether partial or complete, of a custom target pattern. Intrinsic camera parameters of a 5-mm and a 10-mm standard Stryker® laparoscopes obtained using rdCalib and the well-accepted OpenCV camera calibration method were compared. Target registration error (TRE) as a measure of camera calibration accuracy for our optical tracking-based AR system was also compared between the two calibration methods. Based on our experiments, the single-image camera calibration yields consistent and accurate results (mean TRE = 1.18 ± 0.35 mm for the 5-mm scope and mean TRE = 1.13 ± 0.32 mm for the 10-mm scope), which are comparable to the results obtained using the OpenCV method with 30 images. The new single-image camera calibration method is promising to be applied to our augmented reality visualization system for laparoscopic surgery.

Geochronology and structural setting of Latest Devonian – Early Carboniferous magmatic rocks, Cape Kiber, northeast Russia

Cape Kiber on the Arctic coast of Chukotka, northeast Russia, consists of a granite intruding Devonian (and older?) strata in the core of a large southeast trending anticline. These strata are structurally overlain by Carboniferous and younger strata. A U–Pb age of 351.4 ± 5.6 (2σ) Ma shows that the granite is Early Carboniferous in age. A large granite cobble extracted from a Carboniferous conglomerate produced a Late Devonian or Early Carboniferous U–Pb age of ∼355–361 Ma. Also, a deformed and altered granitic dyke yielded an age of 363.7 ± 5.7 (2σ) Ma. Major and trace elements suggest a syn-collisional (orogenic) setting. The granite’s (biotite) Ar release spectrum is reset. The granitic dyke also shows a disturbed Ar–Ar whole-rock spectrum implying an Early Cretaceous age (∼122–130 Ma) for closure of the Ar system. We interpret this as due to widespread greenschist metamorphism accompanying regional deformation of the Anyuy–Chukotka Fold Belt that accompanied closure of the South Anyuy Ocean. Regionally, this event predates deposition of Aptian and Albian strata and the eruption of Okhotsk–Chukotsk magmatic rocks. An Ar–Ar (biotite) plateau age of 96.4 ± 1.0 (2σ) Ma from a mildly deformed, lamprophyre dyke reflects intrusion in a setting of regional extension. Its deformation reflects a younger tectonic event. The record of Devonian–Carboniferous magmatism and early Carboniferous unroofing is younger and less complex than that of Arctic Alaska. However, evidence for Early Devonian (Caledonian) or Late Devonian (Ellesmerian) deformation could have been masked by intense Mesozoic deformation. Outcrop data and geochronology support and refine regional interpretations of Early Cretaceous deformation and mineral growth accompanying accretion of Chukotka to north Asia, followed by regional extension and subsequent convergent deformation.

Calculation and synthesis of ZrC by CVD from ZrCl4–C3H6–H2–Ar system with high H2 percentage

A thermodynamic calculation about the synthesis of ZrC from the ZrCl4–C3H6–H2–Ar system with high percentage of H2 was performed using the FactSage thermochemical software. According to the calculation, ZrC coating was synthesized on graphite substrates and carbon fibers by a low pressure chemical vapor deposition (LPCVD) process, and growth rate of the ZrC coating as a function of temperature was investigated. The surface diagrams of condensed-phases in this system were expressed as the functions of the deposition temperature, total pressure and reactant ratios of ZrCl4/(ZrCl4+C3H6), H2/(ZrCl4+C3H6), and the yield of the products was determined by the diagrams. A smooth and dense ZrC coating could be synthesized under the instruction of the calculated parameters. The morphologies of the ZrC coatings were significantly affected by temperature and gases flux. The deposition temperature is much lower than that from the ZrCl4–CH4–H2–Ar system.

Complex hydrothermal alteration and illite K–Ar ages in Upper Visean molasse sediments and magmatic rocks of the Variscan Badenweiler-Lenzkirch suture zone, Black Forest, Germany

Post-collisional Upper Visean molasse sediments and magmatic rocks of the Badenweiler-Lenzkirch Zone reveal by microscopy of thin sections different degrees of hydrothermal illitization of feldspar and mica particles, and XRD, IR and XRF data of the <2 µm fractions show illitic material as the dominant clay mineral consisting of a mixture of 1M and 2M1 polytypes. Moreover, small amounts of illite/smectite mixed-layer minerals of R1-ordering are proved in the granites. In the separates, two illite mixing lines with different Fe + Mg contents are verified between authigenic illite from feldspar alteration and detrital illite in the molasse sediments, as well as between authigenic illite from feldspar alteration and altered mica flakes in the granites. Fe-rich detrital chlorite is present within the molasse sediments, while mixtures of high aluminous Fe-poor dioctahedral/di-trioctahedral chlorite with randomly interstratified chlorite/smectite mixed-layer minerals are formed from feldspar alteration in the granites. Illite K–Ar dating of the <2 and <0.63 µm fractions yields hydrothermal illitization of feldspar and partial resetting of the K–Ar system of detrital illite and mica flakes in the molasse sediments at ≥200 °C during Upper Permian to Middle Triassic times, while the granites in the eastern part of the study area were not altered contemporaneously. In contrast, hydrothermal activity at ≤200 °C during Upper Jurassic to Lower Cretaceous times occurred in the granites, whereas these temperatures were too low for resetting the older ‘Permo–Triassic’ illite K–Ar ages in the molasse rocks. Within both K–Ar age clusters, the data are seen to decrease with grain size and portion of illite 2M1 polytype. The alteration phenomena indicate multiple hydrothermal episodes in the study area, and they match those from the Central and Western European crust as fluid supply was controlled geodynamically by episodic break up of Pangea.

Viscosity and phase separations of binary CO–He and CO–Ar mixtures

Binary mixtures of 10 and 25 vol% CO in He and 10 vol% CO in Ar have been studied at high pressures and ambient temperature in diamond anvil cells. Phase separations were observed at 5.7(3) GPa, 3.6(2) GPa and 1.6(1) GPa. Earlier studies of –He mixtures of comparable concentrations revealed phase separations at significantly larger pressures, while –Ar mixtures separate at pressures comparable to those observed in the CO–Ar system here. The viscosity of a CO-rich fluid phase was determined by measuring the velocities of rising He bubbles. After corrections for the influence of the finite container size and of remaining helium in CO, the viscosity of the CO-rich fluid at 3.8(1) GPa was ≈3(1) mPa s, similar to what would be expected for isoelectronic liquid under the same conditions.

Thermodynamics for chemical vapor synthesis of Nb nanopowder in NbCl5–H2–Ar system

Thermodynamics for chemical vapor synthesis (CVS) of Nb nanopowder in NbCl5–H2–Ar system was investigated by using FactSage software. The validation experiments were conducted to confirm the thermodynamics points. The results indicate that under the atmospheric pressure, the reduction approach from NbCl5(g) to Nb(s) is a stage-wise process with the formation of complex sub-chlorides, and is controllable at low hydrogen ratio (mole ratio of n(NbCl5):n(H2)<1:180) and low temperature (<1050 °C). Furthermore, a reasonable amount of inert loading gas is favorable to increase the reduction ratio of NbCl5 and the powder yield. The as-synthesized Nb nanopowder with the homogeneous size of 30–50 nm and the powder yield of 85% (mass fraction) is obtained by the CVS process under n(NbCl5):n(H2):n(Ar)=1:120:1 and 950 °C with the NbCl5 reduction rate of 96.1%.

Augmented Reality a Review on Technology and Applications

Abstract We present in this paper an overview of the concepts and potential industrial Augmented Reality applications that can be very efficient. We also present the basic technological requirements for an AR system

Fully quantum state-resolved inelastic scattering of NO(X) + Kr: differential cross sections and product rotational alignment.

Fully quantum state selected and resolved inelastic scattering of NO(X) by krypton has been investigated. Initial Λ-doublet state selection is achieved using an inhomogeneous hexapole electric field. Differential cross sections and even-moment polarization dependent differential cross sections have been obtained at a collision energy of 514 cm(-1) for both spin-orbit and parity conserving and changing collisions. Experimental results are compared with those obtained from quantum scattering calculations and are shown to be in very good agreement. Hard shell quantum scattering calculations are also performed to determine the effects of the different parts of the potential on the scattering dynamics. Comparisons are also made with the NO(X) + Ar system.

Chirality of weakly bound complexes: the potential energy surfaces for the hydrogen-peroxide-noble-gas interactions.

We consider the analytical representation of the potential energy surfaces of relevance for the intermolecular dynamics of weakly bound complexes of chiral molecules. In this paper we study the H2O2-Ng (Ng=He, Ne, Ar, Kr, and Xe) systems providing the radial and the angular dependence of the potential energy surface on the relative position of the Ng atom. We accomplish this by introducing an analytical representation which is able to fit the ab initio energies of these complexes in a wide range of geometries. Our analysis sheds light on the role that the enantiomeric forms and the symmetry of the H2O2 molecule play on the resulting barriers and equilibrium geometries. The proposed theoretical framework is useful to study the dynamics of the H2O2 molecule, or other systems involving O-O and S-S bonds, interacting by non-covalent forces with atoms or molecules and to understand how the relative orientation of the O-H bonds changes along collisional events that may lead to a hydrogen bond formation or even to selectivity in chemical reactions.

Structure evolution and ablation behavior of ZrC coating on C/C composites under single and cyclic oxyacetylene torch environment

ZrC ablation resistance coating was prepared on carbon/carbon composites by low pressure chemical vapor deposition using the ZrCl4–C3H6–H2–Ar system. The structure evolution and ablation behavior of the coating under single and cyclic ablation were investigated in an oxyacetylene torch environment. Single ablation results show that the ablated coating consists of three layers (outer ZrO2 layer, transitional ZrCxOy layer and residual ZrC layer). An oxidation progress is inferred that ZrC is oxidized into ZrCxOy firstly and then into ZrO2 in the case of the continuous diffusion of oxygen. Cyclic ablation results show that the effect of crack growth inhibition and the oxygen diffusion limitation of ZrO2 and ZrCxOy layers dominate the ablation of the coating and result in two different ablation behaviors. Based on the role of the ZrO2 and ZrCxOy layers in the single and cyclic ablation, two different ablation modes of the coating are proposed.

Thermodynamic calculations and kinetic verifications on the chemical vapor deposition process of Si–C–N ceramic from the SiCl3CH3–NH3–H2–Ar precursors

Based on the Gibbs principle of minimum free energy and Factsage software, the thermodynamic phase diagram and three-dimensional yield map were firstly calculated from the SiCl3CH3–NH3–H2–Ar system. The effects of temperature, total pressure, reactant ratios of 3[NH3]/[SiCl3CH3] and [H2]/[SiCl3CH3] on the formation and yield of condensed phases were discussed. Predominant condensed phases at equilibrium were SiC, Si3N4 and graphite phases. The concentration of condensed phase products was used to confirm the composition of Si–C–N. Through the kinetic verification at 1173.15K, it could be demonstrated that Si–C–N ceramics are obtained by chemical vapor deposition from the SiCl3CH3–NH3–H2–Ar system. The deposits were amorphous and mainly constituted by C–C, Si–N and Si–C bonds from XPS analysis, which were well consistent with the results of thermodynamic calculation. The real part and the imaginary part of permittivity were approximately 4 and 0, respectively, which indicated the amorphous deposits possess the low dielectric constant and loss.

Geometrically-Correct Projection-Based Texture Mapping onto a Deformable Object

Projection-based Augmented Reality commonly employs a rigid substrate as the projection surface and does not support scenarios where the substrate can be reshaped. This investigation presents a projection-based AR system that supports deformable substrates that can be bent, twisted or folded. We demonstrate a new invisible marker embedded into a deformable substrate and an algorithm that identifies deformations to project geometrically correct textures onto the deformable object. The geometrically correct projection-based texture mapping onto a deformable marker is conducted using the measurement of the 3D shape through the detection of the retro-reflective marker on the surface. In order to achieve accurate texture mapping, we propose a marker pattern that can be partially recognized and can be registered to an object&#146;s surface. The outcome of this work addresses a fundamental vision recognition challenge that allows the underlying material to change shape and be recognized by the system. Our evaluation demonstrated the system achieved geometrically correct projection under extreme deformation conditions. We envisage the techniques presented are useful for domains including prototype development, design, entertainment and information based AR systems.

Carbon nanocluster growth inside micropipes during the SiC bulk growth process

Carbon nanocluster growth inside micropipes has been discovered during the SiC bulk growth process under near-equilibrium conditions. Measurements have been made of the morphology and structure of the carbon crystallites. An isobaric cross-section of the Si–C phase diagram and an isothermal cross-section of the triple Si–C–Ar system have been built. The C-cluster nucleation and growth conditions have been analyzed using a phase diagram.

Security and privacy for augmented reality systems

AR systems pose potential security concerns that should be addressed before the systems become widespread.

Thermodynamics of the production of condensed phases in the chemical vapor deposition of ZrC in the ZrCl4–CH4–H2–Ar system

Production conditions of ZrC, Zr and C(graphite) condensed phases in the chemical vapor deposition process with ZrCl4–CH4–H2–Ar precursor system have been investigated based on thermodynamic analyses using the FactSage code. The yields of condensed phases have been examined as functions of the injected reactant ratios of ZrCl4/(ZrCl4+CH4), H2/(ZrCl4+CH4) and Ar/(ZrCl4+CH4), the temperature and the pressure. The results show that the yields strongly depend on the molar ratios of the ZrCl4/(ZrCl4+CH4) and H2/(ZrCl4+CH4) injected reactant and on the temperature, but are insensitive to the inert gas Ar ratio and pressure. The co-deposition of ZrC with Zr or C(graphite) can be easily controlled by changing the ratios of ZrCl4/CH4 and H2/(ZrCl4+CH4). Process conditions such as high input amount of H2, relatively low amount of Ar, low pressure and temperature above 1300K are favorable for the deposition of ZrC. The results of this work will be helpful for further experimental investigation on different deposition conditions.

Effects of microstructures on the ablation behaviors of ZrC deposited by CVD

Through changing the H2 concentrations in the H2+Ar dilution gas, different microstructures of ZrC coatings were prepared on carbon/carbon (C/C) composites by low pressure chemical vapor deposition (LPCVD) using ZrCl4–C3H6–Ar system. The effects of microstructure on anti-ablation behaviors of the ZrC coating under oxyacetylene torch were investigated. Results show that the preferred orientation of ZrC coatings transforms from (111) to (200) to (220) and the particle size decrease from micro-scales to nano-scales as the H2 concentrations increase. After ablation for 100s, the coating with in-situ nanoparticles characterized by the (200) preferred orientation exhibits the lowest ablation rates among four samples, which the linear and mass ablation rates were 0.25×10−3mm/s and 0.88×10−4g/cm2/s, respectively. The good ablation resistance of the coating is mainly attributed to the formation of the dense and crack-free ZrO2 layer with ZrO2 nanorods during the ablation.

素手での掴み動作に着目したARシステムの視覚的改良

素手での掴み動作に着目したARシステムの視覚的改良

Potential field emitters: HfC nanorods sheathed with a HfO2 nanoshell

Large-scale hafnium carbide (HfC) nanorods sheathed by a hafnium oxide (HfO2) nanoshell were fabricated using a vacuum catalytic chemical vapor deposition (CVD) method in a HfCl4–C3H6–H2–Ar system containing a small amount of oxygen impurities. The microstructures and morphologies of the products were characterized by an X-ray diffractometer, field-emission scanning electron microscope, transmission electron microscope, and energy-dispersive X-ray spectrometer. The results show that the synthesized needle-like nanostructures, with a diameter of ~100 nm and a length below 2 μm, consist of a HfC core and a HfO2 shell with a thickness of ~5 nm surrounding the core. According to two comparative experiments, a growth mechanism is proposed to explain the formation of the nanorods through a combination of an oxygen-assisted growth process and a root-type vapor–liquid–solid process. The HfC nanorods exhibit excellent field emission (FE) properties with a low turn-on field of 3.2–3.4 V μm−1, high field enhancement factor of 2335, and stable emission current density with a fluctuation below 5% over two hours.

Data Compression and Real-time Color Correction for Photo-based AR System

A Photo-based Augmented Reality system (Photo AR) is a method that implements AR by pasting photo images onto a scene without using a 3D model. Although it eliminates the need to prepare 3D models, it consumes a large volume of disk space. And users of this system may be presented with unnatural images if the lighting conditions in their environment vary too much from those when the photo image was shot. This research discusses a compression method for the photo image data of Photo AR, and also considers methods for correcting the color tone of the image.

Thermodynamic analysis on the codeposition of ZrC–SiC by chemical vapor deposition using the ZrCl4–C3H6–MTS–H2–Ar system

A thermodynamic calculation on co-deposition of ZrC–SiC from the ZrCl4–C3H6–MTS–H2–Ar system was performed using the FactSage thermochemical software and verification experiments were performed. The surface diagrams of condensed-phases in this system were expressed as functions of the deposition temperature, total pressure, reactant ratio of MTS/(MTS+C3H6) and ratio of H2/(ZrCl4+MTS+C3H6), and the composition of the products was determined by the diagram. The calculation results indicate that their yields strongly depend on the molar ratio of the injected reactants and temperature, and ZrC–SiC can be co-deposited under a proper condition. The experimental results show that ZrC–SiC coating was successfully co-deposited on graphite substrates and carbon fibers according to the thermodynamic calculation.