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Objective: To provide technical and clinical recommendations for implementing a digital workflow in Static Computer‐Aided Implant Surgery in the anterior maxilla. Clinical Considerations: An optimal 3D implant position is crucial for achieving satisfying results in implant rehabilitation in the esthetic area. Due to its complexity, implant placement in the esthetic zone should be executed with precision and predictability. Static Computer‐Aided Implant Surgery requires thorough planning and detailed attention to every step of the digital workflow protocol. Conclusions: Implant positioning in the esthetic zone using Static Computer‐Aided Implant Surgery is a technique‐sensitive procedure that requires precise execution of each step. This approach ensures accurate prosthetically driven 3D implant placement and prevents potential errors that could lead to inaccurate positioning. Clinical Significance: The proper implementation of Static Computer‐Aided Implant Surgery may increase the level of agreement between the planned and definitive implant 3D positions in the esthetic zone, thus enhancing the esthetic outcomes of implant rehabilitation. [ABSTRACT FROM AUTHOR]

This article proposes a method for continuous bridge displacement monitoring combining the dynamic triangulation scanning and load estimation by vehicle image recognition. The vehicle–bridge interaction is a non-stationary dynamic process parameter of high relevance to understanding the static instability behavior of bridges. The knowledge of the load on a bridge in the specific time when its structural spatial coordinates are measured allows correlating the bridge displacement with the effect of vehicle–bridge interaction. The evaluation of such correlation is mandatory in order to verify if the observed bridge displacement is due to the nature of its operation or due to it is presenting structural damage. The proposed method is continuous structural health monitoring method, based on the combination of three approaches evaluated at laboratory environment: (1) a three-dimensional optical scanning system for displacement measurement, (2) a load measurement system for vehicle–bridge interaction assessment, and (3) a two-measurement systems data correlation; to be implemented in bridges at a real environment to collect their historical behavior. Overall, for each approach, the measurement systems' principles, the laboratory experimental methodology followed, and results obtained are presented. [ABSTRACT FROM AUTHOR]

Objectives: To compare radiographic bone changes, following alveolar ridge preservation (ARP) using Guided Bone Regeneration (GBR), a Socket Seal (SS) technique or unassisted socket healing (Control). Material and methods: Patients requiring a single rooted tooth extraction in the anterior maxilla, were randomly allocated into: GBR, SS and Control groups (n= 14/). Cone Beam Computed Tomography (CBCT) images were recorded post‐extraction and at 4 months, the mid‐buccal and mid‐palatal alveolar ridge heights (BARH/PARH) were measured. The alveolar ridge width, cross‐sectional socket and alveolar‐process area changes, implant placement feasibility, requirement for bone augmentation and post‐surgical complications were also recorded. Results: BARH and PARH was found to increase with the SS (0.65 mm ± 1.1/0.65 mm ± 1.42) techniques, stabilise with GBR (0.07 mm ± 0.83/0.86 mm ±1.37) and decrease in the Control (−0.52 mm ± 0.8/−0.43 mm ± 0.83). Statistically significance was found when comparing the GBR and SS BARH (p =.04/.005) and GBR PARH (p =.02) against the Control. GBR recorded the smallest reduction in alveolar ridge width (−2.17 mm ± 0.84), when compared to the Control (−2.3 mm ± 1.11) (p =.89). A mid‐socket cross‐sectional area reduction of 4% (−2.27 mm2 ± 11.89), 1% (−0.88 mm2 ± 15.48) and 13% (−6.93 mm2 ± 8.22) was found with GBR, SS and Control groups (GBR vs. Control p =.01). The equivalent alveolar process area reduction was 8% (−7.36 mm2 ± 10.45), 6% (−7 mm2 ± 18.97) and 11% (−11.32 mm2 ± 10.92). All groups supported implant placement, with bone dehiscence noted in 57% (n = 4), 64%(n = 7) and 85%(n = 12) of GBR, SS and Control cases (GBR vs. Control p =.03). GBR had a higher risk of swelling and mucosal colour change, with SS associated with graft sequestration and matrix breakdown. Conclusion: GBR ARP was found to be more effective at reducing radiographic bone dimensional changes following tooth extraction. [ABSTRACT FROM AUTHOR]

• The permissible beryllium tile size, size of defects in the bonding interface, and load on the tile edges were verified by experiments. • Critical technologies of beryllium-armoured component have been successfully qualified by the ITER organization. • The mock-ups with beryllium armour withstood 30,000 cycles at 4.7 MW/m2. • A full-scale prototype of the ITER enhanced-heat flux first wall panel has been manufactured, inspected and tested. The Russian Federation shall supply 179 enhanced heat flux First Wall Panels (FWP) to the ITER construction site. These panels have about 30 types and consist of a steel supporting structure (FW Beam) with multilayer plasma-facing units (PFU) attached onto it. To start the production of the panels, the manufacturing readiness must be confirmed by the ITER Organization (IO). The JSC "NIIEFA" responsible for manufacturing of a part of the components, final assembly and testing of the panels has come a long way from the experimental work on small-scale mock-ups, through the development of the design and key manufacturing technologies to the production and testing of the full-scale prototype (FSP) which is the final step before the confirmation for the manufacture. The manufactured FSP has successfully passed most of the acceptance tests including hydraulic pressure and leak tightness tests. The high heat flux tests have been successfully carried out on the PFUs with beryllium armour. In parallel to the tests of the beryllium prototype, the tungsten armour has been analyzed and tested which is due to the IO's intention to change the armour material. [ABSTRACT FROM AUTHOR]

Recent advances in highly sensitive miniaturized optically pumped magnetometers (OPMs) have enabled the development of wearable magnetoencephalography (MEG) offering great flexibility in experimental setting. The OPM array for wearable MEG is typically attached to a flexible cap and exhibits a variable spatial layout across different subjects, which imposes challenges concerning the efficient positioning and labelling of OPMs. A pair of reflective markers are affixed to each triaxial OPM sensor above its cable to determine its location and sensitive axes. A non-rigid registration of optically digitized marker locations with a pre-labelled template of marker locations is performed to map newly digitized markers to OPMs. The positioning and labelling of 66 OPM sensors could be completed within 35 s. Across ten experiments, all OPMs were accurately labelled, and the mean test-retest errors were 0.48 mm for sensor locations and 0.20 degree for sensitive axes. By combining six OPMs' positions with their respective recordings, magnetic dipoles inside a phantom were located with a mean error of 5.5 mm, and the best fitted dipole for MEG with auditory stimuli presented was located on a subject's primary auditory cortex. The proposed method reduces the reliance on error-prone and laborious manual operations inherent in existing methods, therefore significantly improving the efficiency of OPM positioning and labelling on a flexible cap. We developed a method for the precise and rapid positioning and labelling triaxial OPMs on a flexible cap, thereby facilitating the practical implementation of wearable OPM-MEG. • Positions of 66 OPMs on a flexible cap can be digitized within 35 s. • Mean test-retest errors of location and axis are 0.48 mm and 0.20 degree, respectively. • Automatic algorithms are proposed for labelling OPMs in a flexible array. [ABSTRACT FROM AUTHOR]

Samples of schist, protomylonite, mylonite and ultramylonite from the hanging wall of New Zealand's Alpine Fault were measured using a transient plane source, yielding mean bulk thermal conductivity of 2.04 ± 0.33 W m–1 K–1 in a dry state and 2.78 ± 0.51 W m–1 K–1 in a wet state at room temperature. Corresponding thermal diffusivity is 1.35 ± 0.32×10–6 m2 s–1 in a dry state and 1.72 ± 0.27×10–6 m2 s–1 in a wet state. Thermal conductivity and diffusivity calculated from the mineralogical composition of cuttings from the DFDP-2B borehole in Whataroa Valley and previously published thermal properties of minerals are 3.26 ± 0.16 W m–1 K–1 and 1.56 ± 0.08×10–6 m2 s–1, respectively. We attribute the significant difference in thermal conductivity to regional mineralogical variations in composition of rock samples versus borehole cuttings. Anisotropy of thermal properties is inferred to exist on a centimetre scale, due to competing effects of aligned quartz veins, minerals, and microfractures; but our measurements do not confirm significant anisotropy. Radiogenic heat productivity calculated from geochemical data and a gamma log in DFDP-2B (1.8–2.1 μW m–3) falls within the previously reported range for greywacke and schist. [ABSTRACT FROM AUTHOR]

Sandwich structures used in transportation and energy industries are commonly subjected to low-velocity impact in the course of manufacturing, service and maintenance, which can lead to the premature degradation of structural stiffness and strength. A single non-destructive evaluation technique is often difficult to provide a comprehensive assessment on impact damage from online to offline and from visible to invisible. In the present study, acoustic emission (AE), three-dimensional (3D) optical scanning and X-ray computed tomography (CT) techniques are combined to provide a systematic approach for damage characterization of thick foam-core sandwich panels under low-velocity impact. In the tests, the mechanical responses such as force-time and force-displacement curves are obtained from the testing system. The AE technique is adopted to monitor damage initiation and evolution in situ; optical scanning and X-ray computed tomography techniques are used for off-line damage identification and quantification. The results show that the AE signal waveform stream, cumulative counts and cumulative energy correlate well with the mechanical responses of the sandwich panel under the low-velocity impact, enabling capture of valuable information for online damage monitoring. Unlike general cases, the AE signals generated from low-velocity impact are found to be presented in strong bursts of nearly coincident events in the short duration. Therefore, the distributions of AE amplitude and peak frequency between adjacent AE counts are extracted to study the different damage modes and damage mechanisms. The X-ray computed tomography images enable to precisely visualize the fracture behaviors of the PET foam-core inside the sandwich panel in a nondestructive fashion, which evidently supports the AE and optical scanning results. The study is anticipated to demonstrate effectiveness and capability of the proposed experimental methodology for damage detection and characterization on sandwiched composite structures subjected to impact loading. [Display omitted] • A comprehensive assessment of impact damage is performed using three NDE techniques. • Acoustic emission (AE) is proposed to monitor the initiation and evolution of impact damage on-line. • Peak amplitude and frequency of adjacent AE counts are extracted to study failure modes. • 3D optical scanning and X-ray computed tomography are combined for off-line damage identification. [ABSTRACT FROM AUTHOR]

In this work, the effect of mechanical damage on the thermal conductivity of granite was experimentally investigated. Granite samples were artificially damaged through cyclic loading and unloading tests, with the strain evolution and acoustic emission activity monitored simultaneously. P-Wave velocity of the damaged samples was tested to evaluate the damage effect. Thermal conductivity of the undamaged and damaged granite samples was tested using optical scanning method. The influence of mechanical damage on thermal conductivity was analyzed. Thermal conductivity difference in different testing directions was analyzed based on the experiment results in six scanning lines on the two surfaces of each disk sample. The results indicate that thermal conductivity of damaged samples reduced compared with that of the undamaged samples, while the thermal inhomogeneity factor increased. Thermal conductivity increased in water-saturated condition for both undamaged and damaged samples. The increased rate of damaged samples was bigger than that of the undamaged samples. The mechanical damage treatment caused the increase in the thermal conductivity difference in different testing directions. The difference decreased when samples were water saturated. Research results in this work can provide better knowledge to the evolution mechanism of thermal conductivity of engineering rock masses. [ABSTRACT FROM AUTHOR]

Exchanging broken or worn out turbine blades is an expensive and time critical task that can be cheapened by providing the required spare parts with minimal lead time to shorten inevitable downtimes. Unfortunately, maintenance work is impeded by the absence of easily obtainable part designations or blueprints, which holds in particular for older devices or ones originating from other manufacturers. Here, reverse engineering provides a possible remedy, since a precise geometrical representation of the object can be obtained with comparatively low effort. In addition, modern additive manufacturing methods allow the supply of individual exchange parts at short notice. Therefore, we propose a framework based on optical scanning and computed tomography scans with different acceleration voltages in order to generate a reverse engineered part model. Based on this, a copy of a turbine blade is manufactured by use of selective laser melting. The original workpiece and the replica are investigated for deviations that are quantitatively traced back to inaccuracies originating in the manufacturing method and the data acquisition. We were able to produce a replica that exhibits acceptable geometrical deviations for actual productive service in comparison to the original part as well as the initial design. • Gas turbine overhauls are often impeded by the poor availability of exchange parts. • The combination of reverse-engineering and additive manufacturing might improve the situation. • A turbine blade was scanned via optical and CT-scan and the resulting geometry was 3D-printed. • Sources for geometrical and scanning errors are discussed and quantified separately. • Part replication is possible with acceptable geometrical deviation. [ABSTRACT FROM AUTHOR]

Three-dimensional (3-D) modeling is widely applied in the fields of measurement engineering and manufacturing. Registration of point clouds is a crucial step in 3-D model reconstruction. We present a registration method using improved digital image correlation (DIC) coefficient. First, key points are selected using principal component analysis and further extracted using the k-means clustering algorithm. Second, a grayscale image for each key point is generated as a feature descriptor using inverse distance weighted interpolation. Then, the presented method determines key point correspondences by improving the DIC coefficient. Finally, we apply the iterative closest point algorithm to fine registration. Experiment results show that the proposed method is accurate, time efficient, and it has a good antinoise performance. [ABSTRACT FROM AUTHOR]

Unconventional reservoir rocks frequently exhibit considerable degrees of anisotropy, heterogeneity, and high variability of physical rock properties, reflecting the variety of their geological origins. The anisotropy and heterogeneity can have a pronounced impact on sonic log readings, which poses problems since compressional and shear borehole sonic data are traditionally used both as a data source for geomechanical modelling and also for seismic calibration. Sonic logging and acoustic tests in the laboratory use different frequencies due to the small sample sizes in the laboratory, which, along with known complexities in the measurement/interpretation procedure, complicates the characterization of reservoirs in terms of their elastic properties. This paper proposes a new approach to high-resolution evaluation of the elastic properties and anisotropy of unconventional reservoir rocks, based on continuous non-contact, non-destructive high-resolution (0.2-2 mm) thermal profiling of core samples. Variations in measured thermal characteristics (principal thermal conductivity tensor components, volumetric heat capacity, thermal anisotropy coefficient and thermal heterogeneity coefficient) reflect variations in the rock fabric and composition, which also result in the variability of other properties of the rock. More than 100 m of full-diameter cores along three wells drilled in the Bazhenov formation in West Siberia (Russia) have been profiled. The results were combined with sonic well logging data, and correlations between components of thermal conductivity, density and acoustic velocities were established, as well as correlations between thermal anisotropy, Young’s modulus anisotropy and Thomsen’s parameters. Examples of high-resolution prediction of velocities, density, elastic modulus, and anisotropy parameters based on the results of thermal core logging are given, together with the respective verification. [ABSTRACT FROM AUTHOR]

Process-induced total spring-in of corner-shaped composite parts manufactured via autoclave-forming technique using unidirectional prepreg is studied both numerically and experimentally. In the numerical study, a three-dimensional finite element model which takes into account the cure shrinkage of the resin, anisotropic material properties of the composite part and the tool-part interaction is developed. The outcome of the numerical model is verified experimentally. For this purpose, U-shaped composite parts are manufactured via autoclave-forming technique. Process-induced total spring-in, due to the combined effect of material anisotropy and tool-part interaction, at different sections of the U-shaped parts are measured with use of the combination of the three-dimensional optical scanning technique and the generative shape design. Total spring-in determined by the numerical model is found to be in good agreement with the average total spring-in measured experimentally. The effect of tool-part interaction mechanism on the total spring-in is studied separately to ascertain its effect on the total spring-in behavior clearly. It is shown that with the proper modeling of the tool-part interaction, numerically determined total spring-in approaches the experimentally determined total spring-in. [ABSTRACT FROM AUTHOR]

Three dimensional (3-D) modeling is important in applications ranging from manufacturing to entertainment. Multiview registration is one of the crucial steps in 3-D model construction. The automatic establishment of correspondences between overlapping views, without any known initial information, is the main challenge in point clouds registration. An automatic registration algorithm is proposed to solve the registration problem of rigid, unordered, scattered point clouds. This approach is especially suitable for registering datasets that are lacking in features or texture. In general, the existing techniques exhibit significant limitations in the registration of these types of point cloud data. The presented method automatically determines the best coarse registration results by exploiting the statistical technique principal component analysis and outputs translation matrices as the initial estimation for fine registration. Then, the translation matrices obtained from coarse registration algorithms are used to update the original point cloud and the optimal translation matrices are solved using an iterative algorithm. Experimental results show that the proposed algorithm is time efficient and accurate, even if the point clouds are partially overlapped and containing large missing regions. [ABSTRACT FROM AUTHOR]

In order to ensure and extend the serviceability of sewage infrastructure, sewer managers need more accurate data to estimate its actual state. For that purpose, various inspection techniques can be implemented. A first prototype of an unbiased laser profiler was developed to improve the accuracy of collected data (Clemens, Stanić, Van der Schoot, Langeveld, Lepot, 2015). However, a higher accuracy needs to be achieved. This article presents the results of an improved prototype that delivers an increase in the measuring accuracy of 5–10 times, which was achieved by using more accurate equipment (lasers and cameras) and by improvements in the methodologies applied (e.g. removing the last bias image distortion by camera calibration). The new design presented hereafter provides accurate measurements (σ < 2 mm) of cross section and accurate 3D image of a pipe. The potential applications of the improved laser profiling technique are comprehensive: e.g. deposit measurements, roughness measurements. [ABSTRACT FROM AUTHOR]

In sewer asset management, decision making on rehabilitation or replacement should preferably be based on the actual functionality of a sewer system. In order to judge the ability of a sewer system to transport wastewater, hydrodynamic models are used; in these, hydraulic roughness is one of the key parameters. For new pipes, this is well known, but for aged pipes with uneven deterioration along the cross section, information on the hydraulic roughness is lacking. In this article, the potential of laser scanning methods for accurate, noninvasive, and nonintrusive assessment of the hydraulic roughness of concrete sewer pipes is described, demonstrated, and discussed. Processing of raw scanned data consists of two steps: (1) spatial interpolation with uncertainty analysis, and (2) statistical analysis for estimating the hydraulic roughness. Moreover, a statistical analysis was carried out to determine the minimal scanning resolution required in order to yield results accurate enough for subsequent modeling uses. The results show a promising potential of the laser scanning approach for a simple and fast quantification of the hydraulic roughness in a sewer system. [ABSTRACT FROM AUTHOR]

This publication presents the results of optical scanning of a 682-type die for forging of synchronizer rings and of metallographic examinations, which were performed after exploitation of the die. The die was manufactured and exploited at the Fabryka Armatur "Swarzędz" Sp. z o.o. After heat treatment, the die was subjected to ZeroFlow gas nitriding at the Poznań University of Technology, in a two-step process according to the following parameters: 1st step: 490°C, 1 h, Np=15 atm-1 2nd step: 550°C, 43.5 h, Np=0.3 atm-1/2. The nitrided layer was characterized by near-surface hardness of approx. 1000 HV 0.1, thickness amounting to 0.25 mm, and only fine precipitations of iron nitrides in the interior nitriding zone. ZeroFlow nitriding technology was to be competitive to ion nitriding conducted at a temperature of approx. 550°C over 10 h due to the absence of a network of γ'-phase precipitations in the structure of the α diffusion zone. Susceptibility of nitrided layers with a network system of iron nitride precipitations to chipping during operation was observed in earlier studies. Optical scanning of the die was performed after the nitriding process and after exploitation of the die. It was planned to make 3000 synchronizer rings using the studied die. However, after 2500 ring forging cycles, bending of rings was observed. This is why metallographic examinations were performed on specimens cut out from the die in order to explain the causes of its premature wear-out. The greatest die wear occurred in areas of the radius of the surface forming the surface of the synchronizer ring and the edge of the hole with a diameter of approx. 104 mm. The largest cracks and greatest reduction of the nitrided layer were observed in these areas. [ABSTRACT FROM AUTHOR]

Miniature piezoelectric actuators are commonly used as a compact means to relay images for numerous endoscopic applications. These scanners normally consist of an electrically driven lead zirconate titanate (PZT) tube that oscillates an optical fiber at its resonant frequency. The diameter and length of the PZT and fiber, the attachment of the fiber to the PZT, as well as the driving signal determine the main characteristics of the scan--frequency and amplitude of vibration. We present a new, robust, and repeatable method for producing miniature PZT actuators. The described technology allows for continuous tuning of the scanner mechanical properties during the assembly stage, enabling adjustment of resonant frequency and subsequent amplitude of vibration without a priori knowledge of the fiber's mechanical properties. The method consists of manufacturing high-precision fiber-holding plastic inserts with diamond turning lathes that allow for the fiber length to be quickly varied and locked during operation in order to meet the preferred performance. This concept of tuned PZTs was demonstrated with an imaging technique that combined two scanners oscillating in unison at the ends of a single optical fiber to relay images without the need to correlate the driving signal with a detector. [ABSTRACT FROM AUTHOR]

Background Several studies link the seamless fit of implant-supported prosthesis with the accuracy of the dental impression technique obtained during acquisition. In addition, factors such as implant angulation and coping shape contribute to implant misfit. Purpose The aim of this study was to identify the most accurate impression technique and factors affecting the impression accuracy. Material and Methods A systematic review of peer-reviewed literature was conducted analyzing articles published between 2009 and 2013. The following search terms were used: implant impression, impression accuracy, and implant misfit. A total of 417 articles were identified; 32 were selected for review. Results All 32 selected studies refer to in vitro studies. Fourteen articles compare open and closed impression technique, 8 advocate the open technique, and 6 report similar results. Other 14 articles evaluate splinted and non-splinted techniques; all advocating the splinted technique. Polyether material usage was reported in nine; six studies tested vinyl polysiloxane and one study used irreversible hydrocolloid. Eight studies evaluated different copings designs. Intraoral optical devices were compared in four studies. Conclusions The most accurate results were achieved with two configurations: (1) the optical intraoral system with powder and (2) the open technique with splinted squared transfer copings, using polyether as impression material. [ABSTRACT FROM AUTHOR]

The paper describes the ballistic impact test, in which fragment simulating projectiles (FSPs) of a 20-mm-diameter have been used against 40-mmthick plates made of an aluminum alloy AA7020-T651. To perforate plates, the projectiles must have reached a velocity higher than 890 m/s. Based on the performed ballistic test, the plugging failure mode is numerically modeled using the LS-DYNA software package. Results obtained due to the calculations in the Finite Element Method (FEM) are compared with the results from the Smoothed Particle Hydrodynamics (SPH). A condition of geometrical similarity between the target deformed experimentally and its numerical representation is introduced to evaluate the performed simulations. [ABSTRACT FROM AUTHOR]

An analysis software was developed for the high aspect ratio optical scanning system in the Detector Laboratory of the University of Helsinki and the Helsinki Institute of Physics. The system is used e.g. in the quality assurance of the GEM-TPC detectors being developed for the beam diagnostics system of the SuperFRS at future FAIR facility. The software was tested by analyzing five CERN standard GEM foils scanned with the optical scanning system. The measurement uncertainty of the diameter of the GEM holes and the pitch of the hole pattern was found to be 0.5 μ m and 0.3 μ m , respectively. The software design and the performance are discussed. The correlation between the GEM hole size distribution and the corresponding gain variation was studied by comparing them against a detailed gain mapping of a foil and a set of six lower precision control measurements. It can be seen that a qualitative estimation of the behavior of the local variation in gain across the GEM foil can be made based on the measured sizes of the outer and inner holes. [ABSTRACT FROM AUTHOR]

The aims of this study were to enable geometric morphometric sex classification using tibial proximal and distal sexual dimorphism and to evaluate the secular trend of tibial shape/form from the early 20th century to the present day. The study samples consisted of 61 adult tibias from an early 20th-century Czech population and 57 three-dimensional tibias from a 21st-century population. Discriminant function analysis with cross-validation was carried out to assess the accuracy of sex classification. Shape analysis revealed significant sex differences in both tibial extremities of the 21st-century sample and in the proximal tibia of the 20th-century population. Sex-based divergence varied between the analyzed samples, raising the issues of population specificity and diachronic change. Classification using tibial form was more successful than using tibial shape. The highest values of correct assignment (91.80% and 88.52%) were found using the form from the early 20th Czech population. [ABSTRACT FROM AUTHOR]

Altering in surface forms cause to varying cutting forces in machining of inclined surfaces by ball end mills. The deflections appeared by cutting forces can result in form defects in workpiece. Finding deflection values and related form defects has a significant importance for keeping the production within the appropriate tolerances and in lessening production costs. The aim of this study is to evaluate form defects depending on tool deflection in milling of inclined convex and concave surfaces of EN X40CrMoV5-1/DIN 1.2344 using TiAlN-coated cutting tool. The experiments have been conducted with different cutting tools strategies and cutting parameters at related parameter levels. During machining real time cutting tool deflections are recorded by inductive sensors for the experiments. Then, the form defects of machined specimens caused by cutting tool deflections are determined by 3D optical scanning. The cutting tool deflection values and the values of 3D optical scanning form defects have been compared. The largest cutting tool deflections and form defects are detected at the ramping regions with the milling position angles of 45° to 60° for the convex and concave surface types. In addition, the regions that the largest tool deflections have been observed are the same regions with the largest form defects obtained by the optical scanning. As a result, at the determination of form defects caused by cutting tool deflection, the deflection values obtained by real time measurement are coincided with the measurement obtained from 3D optical scanning. [ABSTRACT FROM AUTHOR]

This work proposes a two-dimensional (2-D) laser scanning mirror with a novel actuating structure composed of one magnet and two coils. The mirror-actuating device generates decoupled scanning motions about two orthogonal axes by combining two electromagnetic actuators of the conventional moving-coil and the moving-magnet types. We implement a finite element analysis to calculate magnetic flux in the electromagnetic system and experiments using a prototype with the overall size of 22 mm (W) × 20 mm (D) × 15 mm (H) for the mirror size of 8 mm × 8 mm. The upper moving-coil type actuator to rotate only the mirror part has the optical reflection angle of 15.7° at 10 Hz, 90° at the resonance frequency of 60 Hz at ± 3 V (± 70 mA) and the bandwidth of 91 Hz. The lower moving-magnet type actuator has the optical reflection angle of 16.20° at 10 Hz and 50° at the resonance frequency of 60 Hz at ± 5 V (± 34 mA) and the bandwidth of 88 Hz. The proposed compact and simple 2-D scanning mirror has advantages of large 2-D angular deflections, wide frequency bandwidth and low manufacturing cost. [ABSTRACT FROM AUTHOR]

In the field of dental health care, plaster models combined with 2D radiographs are widely used in clinical practice for orthodontic diagnoses. However, complex malocclusions can be better analyzed by exploiting 3D digital dental models, which allow virtual simulations and treatment planning processes. In this paper, dental data captured by independent imaging sensors are fused to create multi-body orthodontic models composed of teeth, oral soft tissues and alveolar bone structures. The methodology is based on integrating Cone-Beam Computed Tomography (CBCT) and surface structured light scanning. The optical scanner is used to reconstruct tooth crowns and soft tissues (visible surfaces) through the digitalization of both patients' mouth impressions and plaster casts. These data are also used to guide the segmentation of internal dental tissues by processing CBCT data sets. The 3D individual dental tissues obtained by the optical scanner and the CBCT sensor are fused within multi-body orthodontic models without human supervisions to identify target anatomical structures. The final multi-body models represent valuable virtual platforms to clinical diagnostic and treatment planning. [ABSTRACT FROM AUTHOR]

Background: The accuracy of implant casts generated with various impression techniques was mainly investigated in vitro resulting in limited clinical data. Purpose: (1) To compare the three-dimensional (3-D) accuracy of splinted and non-splinted impression techniques to the control casts (verification jigs) that had been used for actual patient treatment; and (2) to determine the maximum level of clinically undetectable misfit. The null hypothesis was that there would be no significant difference in the accuracy of casts generated with different impression techniques. Materials and methods: The implant casts used for the prosthetic rehabilitation of 12 edentulous jaws with CAD/CAM zirconia, implant-fixed complete dental prosthesis (IFCDP) were included in this study. Intraoral acrylic jigs were used to fabricate index casts. Splinted and non-splinted, open-tray techniques were used to generate two casts. Optical scanning acquisition of the x-coordinates, y-coordinates and z-coordinates of the implant positions for each individual cast was performed. The 'best fit' algorithm was used with computer software to superimpose the scanning datasets. Group I ( n=12) included casts from the splinted impression technique vs. acrylic jig casts, and group II ( n=12) included casts from non-splinted technique vs. jig casts. Results: The paired t-test and Wilcoxon's signed ranks test were used to compare the 3-D discrepancies within and between groups I (splinted vs. jig) and II (non-splinted vs. jig), respectively. Significant difference was found at the x-axis, y-axis and 3-D between groups I and II ( P<0.05), but not in the vertical z-axis ( P>0.05). Within subject, global 3-D discrepancies between groups I and II were significantly different ( P<0.05), corroborated by in vivo observations of clinical fit. Implant position in the arch affected the 3-D accuracy of casts for both anterior and posterior implants ( P<0.05). Conclusion: The splinted technique generated more accurate master casts than the non-splinted technique for one-piece IFCDPs in edentulous jaws and the null hypothesis was rejected. These clinical implications demonstrate improved accuracy of splinted impression techniques compared with the non-splinted technique. For the external connection, the implant system used in this study, a 3-D misfit ranging from 59 to 72 μm, may be considered the maximum discrepancy resulting in an acceptable clinical fit with one-piece IFCDPs. [ABSTRACT FROM AUTHOR]

Consumer electronics are ever more sophisticated in terms of esthetics and design. Due to mass production, the required sampling quantity for quality inspection of products has surged considerably. As such, learning how to utilize the appropriate device and methodology to accomplish free-form surface measuring in an efficient, precise, and timely way has become a very important topic for quality control of the design of consumer electronics. Focusing on the overlap interference problem of fan blades produced in the axial fan blades, this research proposes a geometric calculation algorithm and calculates the suitable measuring orientation, which can be used to evade the interference area of the surface of each fan blade, so as to achieve the objective of automatic measuring. Meanwhile, this research develops a visual software system to simulate the actual optical scanning orientation of non-contact measuring, intending to let users observe the optical scanning orientation of fan blades and estimate the measuring results through the simulated images. Finally, by the way of real measuring, this paper proves the feasibility and convenience of this research. [ABSTRACT FROM AUTHOR]

Dynamic behavior of magnetic thin film actuators is investigated in detail and applied to various laser scanning applications. Magnetic hysteresis effects are incorporated into the model developed in the prior work, which assumes linear magnetization as a function of magnetic field and is based on the distributed point-by-point calculation of the magnetostatic moments and forces across the film surface. A simple functional form is used to model the major B--H loop of ferromagnetic films. The model is validated with permalloy (Ni-Fe) plated polymer actuators. The actuators are excited using an external electro-coil and the structures deflect due to magnetic anisotropy torque. The ac deflection of the actuators is modeled by calculating the point-by-point moments on the magnetic film and the solution can handle nonuniform external field and unsaturated magnetic film cases. A 25° optical scan angle is demonstrated for laser scanning display and imaging applications with a nonoptimum coil. Scaling the model to MEMS devices is also discussed. [ABSTRACT FROM AUTHOR]

High moisture extrusion has been used to produce vegetable meat analogues that resemble real animal meat and can provide significant health benefits. Since visual and textural properties are key factors for consumer acceptance, assessing fiber formation in the extruded products is important for quality control purpose. Recently, we developed a nondestructive photon migration method to quantify fiber formation in meat analogues. In this study, we implemented this technique in a real-time optical scanning system. This system can scan the entire sample area in real-time and provide 2-dimensional maps to visualize the degree of fiber formation and fiber orientation in the sample. The new system has a potential to provide a fast, nondestructive means for online monitoring of the fiber formation in meat analogues. [ABSTRACT FROM AUTHOR]

Abstract: Optomechanical scanning systems with focused laser spot are used in several applications including microstereolithography (MSL), scanning optical tweezers, and laser cutting. Systems used so far in the literature for scanning a focused laser spot on a substrate are: (a) galvanomirror preobjective scanning, (b) galvanomirror postobjective scanning and (c) ‘off-axis’ lens scanning system (originally proposed by coauthors). Major performance criteria due to end application, (say for example, to obtain high resolution microdevices in MSL) translates into the following criteria on optical scanning system: (i) uniform spot size and (ii) uniform intensity profile over the entire range of scan. This paper presents comparative optical analysis, both theoretical and experimental, of these systems based on the proposed performance criteria. Optical analysis of the optomechanical scanning systems is carried out by using geometric ray tracing method. Image evaluation in this case is done using diffraction wave optics. Simulations are carried out to determine spot characteristics at image plane when scan distances are changed by moving optics in the above mentioned optomechanical scanning systems. Simulation and experimental results clearly show that there is lesser distortion of spot characteristics (size and intensity profile) in case of proposed off-axis lens scanning system as compared to other systems over wider scan range. Hence this system is more promising to fabricate high resolution micro-components and in general for other similar applications as well. [Copyright &y& Elsevier]

• Automatic algorithms are proposed for the coregistration of MRI and on-scalp MEG. • The location and orientation errors are less than 1 mm and 0.6°, respectively. • The method is applicable to both rigid and flexible helmets. Recent progress in optically pumped magnetometers (OPMs) and high-temperature superconducting quantum interference devices (SQUIDs) has facilitated the development of an on-scalp magnetoencephalography (MEG) system that offers high signal intensity and flexibility at a lower cost. While the on-scalp sensor array has high flexibility, it brings new challenges to accurate sensor-to-brain coregistration, which is essential for MEG source localization. A novel automatic filtering algorithm based on plane segmentation was proposed to locate on-scalp MEG sensors in 3D images reconstructed from optical scanning. Global image registration was employed for the automatic alignment of anatomical images and sensor positions. Seventy-one sensor dummies on the scalp were located and registered to brain anatomical images. The deviations of the sensor location and orientation from the averaged result of 10 measurements were less than 1 mm and 0.6°, respectively. The entire process could be completed in less than 4 min. Compared with existing methods that involve various manual procedures, such as moving digitizers to fiducials and repeatedly pulling out sensors, our proposed coregistration method is more efficient and accurate. An automatic method for the coregistration of anatomical structure and on-scalp sensors that will have a large impact on the practical use of on-scalp MEG is developed. [ABSTRACT FROM AUTHOR]

Abstract: The spatial light modulators (SLMs) at the Fourier planes of a conventional joint-transform correlation (JTC) are eliminated using simple grating filters such as rectangular and triangular ones. To achieve this goal, two non-conventional real-time JTC architectures are proposed: (a) the grating filter is used along with a heterodyning and one-dimensional optical scanning technique to capture the cross-correlation functions of the input images without major processing and (b) the one-dimensional optical scanning is eliminated to achieve a faster (but a little bit more complicated) processing. The proposed techniques significantly reduce the time processing needed for real-time applications by eliminating the drawbacks of the non-ideal characteristics of the SLMs. [Copyright &y& Elsevier]

Abstract: A silicon resonant torsional micro-mirror excited by piezoelectric bimorph actuators is presented. The bimorph actuators consist of a single-crystal silicon flexible beam or membrane and a PZT thin film. The mechanical elements are etched in the 20μm thick superficial layer of a SOI substrate, thereby ensuring the flatness of the 500μm-diameter gold-coated mirror. This device achieves optical beam scanning with large angular deflection at high frequency. In air, we have measured scanning up to 19.8° at 1.8kHz, 99.1° at 10.6kHz and 40.8° at 25.4kHz. The applied driving voltage is sinusoidal with an amplitude under 42VPP and with a 6VDC bias voltage. At large oscillation amplitude, a non-linear hard-spring effect has been observed. In vacuum, a 78° optical scanning has been obtained with less than 1VPP. [Copyright &y& Elsevier]

— The success of the Soultz-sous-Forêts Hot-Dry-Rock project depends on the ability to maintain fluid circulation in a fractured granite. Fractures represent the main fluid pathways. To understand the behavior of this granite in respect to thermal fluid-rock interaction the important aspects are (1) the porous network around these fractures and (2) the thermal conductivity of the rock. This granite is altered and composed of different weathered facies. Variations of porosity and thermal conductivity take place in regard to the alteration and fracturing of the granite. Two types of porosity measurements were performed, mercury injection and water porosity on two samples sizes. The two methods give similar porosity values between 0.3% and 10%. Thermal conductivity measurements were performed in two perpendicular directions to look at anisotropy with two methods at different scale and value ranges from 2.3 to 3.9 W.m-1.K-1. Optical scanning provides us with a good knowledge of local increase of thermal conductivity due to sealed fracture or quartz-cemented matrix. The relationship between porosity and thermal conductivity is not obvious and has to be studied in details, and results show three cases: (1) a relationship between conductivity and porosity (increase of conductivity with a decrease of porosity), (2) a relationship between conductivity and sealed fractures (increase of conductivity related to an increase of fracture density), (3) and a combination of the two previous ones. The results are carefully compared for different types of granite: alterated, fractured or both. These first results indicate that parameters such as thermal conductivity are linked to the porous medium, the structure and the mineralogy of the rock. [ABSTRACT FROM AUTHOR]

In this work, thermal damage effect on the thermal conductivity inhomogeneity of granite was experimentally investigated. To study the influence of different cooling methods, granite samples were heated at different temperature levels (from 100°C to 1000 °C), then cooled in air and water, respectively. Distributed thermal conductivity of granite samples were measured using optical scanning method before and after thermal damage treatment. Besides, some non-destructive tests (open porosity and P-wave velocity) were performed. The results indicate that thermal damage will lead to the decrease of thermal conductivity and the increase of thermal inhomogeneity degree. The decrease degree of thermal conductivity values increases with the treatment temperature. The maximum decrease can be 54.0% (after heated at 1000 °C). When the treatment temperature is higher than the phase transition temperature of quartz (573 °C), the thermal inhomogeneity degree of the damaged samples increased obviously. After heated at each temperature level, the water cooled samples exhibit greater thermal conductivity decrease and greater thermal inhomogeneity factor increase than air cooled samples. This may be attributed to the fact that rapid cooling has extra effects on the damage evolution of rock, which is induced by the high temperature gradient generated when temperature changes occur in a very short time. A thermal damage model was proposed to describe the evolution characteristics of thermal conductivity with treatment temperature. Research results in this work can provide better knowledge to the evolution mechanism of distributed thermal conductivity of engineering rock masses experienced high temperature environment, and the influence of different cooling methods. [ABSTRACT FROM AUTHOR]

The article presents a study on the use of cross-polarized fiber-coupled heterodyne interferometer system with a micro-electro-mechanical system (MEMS) mirror and an f-theta lens for scanning optical glass. The study uses 2µm laser beams and with MEMS mirror and f-theta lens to measure a 300 millimeter (mm) diameter sample. Result shows that the system takes 5 seconds (s) to scan sample and shows advantage of higher transmission coefficient, less time loss, and reduced tiny vibration.

• Granites were artificially damaged through cyclic loading and unloading tests. • Temporal and spatial evolution of AE events were obtained. • 2D thermal conductivity images were obtained using optical scanning method. • Influence of mechanical damage on the distributed thermal conductivity was investigated. In this work, influences of mechanical damage and water saturation on the distributed thermal conductivity of granite were experimentally investigated. The samples were artificially damaged using uniaxial cyclic loading and unloading tests, with acoustic emission activity monitored simultaneously. 2D thermal conductivity images were obtained using optical scanning method for both undamaged and damaged samples in dry and saturated conditions. The results indicate that the overall thermal conductivity of the samples decreased after mechanical damage treatment, while the thermal inhomogeneity factor increased. The thermal conductivity difference distribution matched well with the spatial distribution of acoustic emission events. The overall thermal conductivity values increased after water saturation in vacuum condition for both undamaged and damaged samples. Thermal inhomogeneity factor didn't change significantly when undamaged samples were saturated, while thermal inhomogeneity factor of damaged samples decreased to a certain extent when samples were saturated. Research results in this work can provide better knowledge to the evolution mechanism of distributed thermal conductivity of engineering rock masses. [ABSTRACT FROM AUTHOR]

Fingerprint authentication is a preferable biometric technique for securing images. Optical scanning cryptography (OSC) is a hybrid optical/digital method to encrypt and decrypt an image using optical scanning technique. In this paper, we propose a new strategy to combine OSC with fingerprints to enhance security. We have verified the effectiveness of the proposed idea in simulations. Subsequently practical implementation of the idea has also been performed with optical heterodyning to confirm the results from simulations. We have also discussed the added security and flexibility of implementation when optical heterodyning is employed in cryptography. [ABSTRACT FROM AUTHOR]