Multi-scan Method Research Articles

Precise mode control of laser-written waveguides for broadband, low-dispersion 3D integrated optics

Three-dimensional (3D) glass chips are promising waveguide platforms for building hybrid 3D photonic circuits due to their 3D topological capabilities, large transparent windows, and low coupling dispersion. At present, the key challenge in scaling down a benchtop optical system to a glass chip is the lack of precise methods for controlling the mode field and optical coupling of 3D waveguide circuits. Here, we propose an overlap-controlled multi-scan (OCMS) method based on laser-direct lithography that allows customizing the refractive index profile of 3D waveguides with high spatial precision in a variety of glasses. On the basis of this method, we achieve variable mode-field distribution, robust and broadband coupling, and thereby demonstrate dispersionless LP21-mode conversion of supercontinuum pulses with the largest deviation of <0.1 dB in coupling ratios on 210 nm broadband. This approach provides a route to achieve ultra-broadband and low-dispersion coupling in 3D photonic circuits, with overwhelming advantages over conventional planar waveguide-optic platforms for on-chip transmission and manipulation of ultrashort laser pulses and broadband supercontinuum.

The Application of Terrestrial Light Detection and Ranging to Forest Resource Inventories for Timber Yield and Carbon Sink Estimation

New technologies are utilized to improve forest management, but they require the collection and analysis of digital data. This study assessed the applicability of using light detection and ranging (LiDAR) devices for the examination of forest resource inventories to obtain digital forest resource information. Two terrestrial LiDARs, a backpack laser scanner (BPLS) and a terrestrial laser scanner (TLS) were used and compared with the traditional method to identify which was optimal. The findings showed that the TLS single-scan method was least accurate due to occlusion. The TLS multi-scan method and the BPLS showed high levels of accuracy for the height and diameter at breast height (DBH) estimates in most sample plots. However, the BPLS underestimated height to a greater extent than the other methods in a sloped plot (24°). Nevertheless, the efficiency of the BPLS was 2.8 times higher than that of the TLS when considering the amount of time spent on completing all indoor and outdoor tasks. Thus, these results prove that the utilization of LiDAR devices increases the efficiency of data collection and overcomes the limitations of existing methods. Moreover, they provide accurate information that will be a basis for forest management plans, the estimation of biomass, and the transaction of forest products.

Electronic Mapping of a Bacterial Genome with Dual Solid-State Nanopores and Active Single-Molecule Control.

We present an electronic mapping of a bacterial genome using solid-state nanopore technology. A dual-nanopore architecture and active control logic are used to produce single-molecule data that enables estimation of distances between physical tags installed at sequence motifs within double-stranded DNA. Previously developed "DNA flossing" control logic generates multiple scans of each captured DNA. We extended this logic in two ways: first, to automate "zooming out" on each molecule to progressively increase the number of tags scanned during flossing, and second, to automate recapture of a molecule that exited flossing to enable interrogation of the same and/or different regions of the molecule. Custom analysis methods were developed to produce consensus alignments from each multiscan event. The combined multiscanning and multicapture method was applied to the challenge of mapping from a heterogeneous mixture of single-molecule fragments that make up the Escherichia coli (E. coli) chromosome. Coverage of 3.1× across 2355 resolvable sites of the E. coli genome was achieved after 5.6 h of recording time. The recapture method showed a 38% increase in the merged-event alignment length compared to single-scan alignments. The observed intertag resolution was 150 bp in engineered DNA molecules and 166 bp natively within fragments of E. coli DNA, with detection of 133 intersite intervals shorter than 200 bp in the E. coli reference map. We present results on estimating distances in repetitive regions of the E. coli genome. With an appropriately designed array, higher throughput implementations could enable human-sized genome and epigenome mapping applications.

Multifield acquisition technology for a narrow beacon laser on the non-orbit determination platform.

The application of free space optical communications technology between unmanned airborne vehicles (UAVs) can significantly improve its communications rate and capacity. However, it will produce strong disturbance due to the change of external conditions when the UAV is flying, which will affect the acquisition probability of a light beacon. The wide beacon can generally increase the acquisition range and acquisition probability, but there are disadvantages of increased weight and energy consumption. We report on an advanced method to improve the performance of narrow beacon spatial acquisition under the condition of UAV drift. The acquisition probability model has been established to study narrow beacon spatial acquisition considering UAV drift. A multiscanning method is proposed to improve the acquisition probability instead of simply increasing the scanning area to overcome severe UAV drift, which is also proven by experimental validation. Moreover, through the control method of active disturbance rejection control (ADRC), the pointing accuracy of multifield fast scanning is improved under the condition of external interference. This technique is extremely useful to develop a smaller, lighter terminal for UAV optical communications in the future.

Analysis of Coal Spontaneous Combustion by Thermodynamic Methods

ABSTRACT In order to better determine the spontaneous combustion tendency of coal, two types of heating rate methods, namely, single and multi-scan methods, commonly used in the field of spontaneous coal combustion are summarized based on a thermal analysis kinetics method. The single scanning rate method mainly included the Coats–Redfern, Achar, universal equation, MacCallum–Tanner, Madhusudanan–Krishnan–Ninan, and non-isothermal thermogravimetric and differential scanning calorimetric methods. The multi-scan rate method mainly included the Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Starink, and Friedman methods. For each of these methods, their respective theoretical basis, advantages, and disadvantages were described. In addition, the Popesc and Malek methods were used to determine the optimal reaction kinetic model. In view of the compensation effect, the invariable activation energy E inv and the pre-exponential factor lnAinv at different heating rates were determined. For each method, the oxygen weight gain stage of Shaanxi bituminous coal was selected as an example interpretation.

Development of a relationship between kinetic triplets and heating rates to improve pyrolysis kinetic modeling of polymer

Pyrolysis kinetic modeling of polymers is important for the analyses of their combustibility and flame spread mechanism in fire safety science and engineering. The objective of this work is to improve the reliable kinetic parameter analyses for polymers by introducing a new idea of the linear dependence of kinetic triplets on the heating rates in Thermogravimetric Analysis (TGA) experiments. The virtual kinetic triplets are also introduced for the case with the infinitely slow heating rate. Pyrolysis kinetic analyses are conducted by Genetic Algorithm (GA) optimization for the TGA data based on the single-scan, multi-scan and the new method here with the modified kinetic triplet series. The results show that the fitting errors for the independent case based on the single-scan method can be as small as 0.1–0.5%. But Kinetic Compensation Effects (KCE) problem is its main restriction to hinder the determination of reliable kinetic triplets. The results also show that based on the multi-scan method, the relatively reliable kinetic parameters can be calculated but with large total fitting errors in the range of 4.7–9.8%. Finally, the total fitting error can be minimized to about 0.6–1.7% by the new method here, which illustrates its obvious improvement for the reliable pyrolysis kinetic modeling of fuels. The new method based on the kinetic triplet series here is a modified multi-scan method, in which the traditional multi-scan method is also included as the case with the linear coefficient of zeros.

Evaluating Different Methods for Estimating Diameter at Breast Height from Terrestrial Laser Scanning

The accurate measurement of diameter at breast height (DBH) is essential to forest operational management, forest inventory, and carbon cycle modeling. Terrestrial laser scanning (TLS) is a measurement technique that allows rapid, automatic, and periodical estimates of DBH information. With the multitude of DBH estimation approaches available, a systematic study is needed to compare different algorithms and evaluate the ideal situations to use a specific algorithm. To contribute to such an approach, this study evaluated three commonly used DBH estimation algorithms: Hough-transform, linear least square circle fitting, and nonlinear least square circle fitting. They were each evaluated on their performance using two forest types of TLS data under numerous preprocessing conditions. The two forest types were natural secondary forest and plantation. The influences of preprocessing conditions on the performance of the algorithms were also investigated. Results showed that among the three algorithms, the linear least square circle fitting algorithm was the most appropriate for the natural secondary forest, and the nonlinear least square circle fitting algorithm was the most appropriate for the plantation. In the natural secondary forest, a moderate gray scale threshold of three and a slightly large height bin of 0.24 m were the optimal parameters for the appropriate algorithm of the multi-scan scanning method, and a moderate gray scale threshold of three and a large height bin of 1.34 m were the optimal parameters for the appropriate algorithm of the single-scan scanning method. A small gray scale threshold of one and a small height bin of 0.1 m were the optimal parameters for the appropriate algorithm of the single-scan scanning method in the plantation.

Osteocyte-directed bone demineralization along canaliculi

The mammalian skeleton stores calcium and phosphate ions in bone matrix. Osteocytes in osteocyte lacunae extend numerous dendrites into canaliculi less than a micron in diameter and which are distributed throughout bone matrix. Although osteoclasts are the primary bone-resorbing cells, osteocytes also reportedly dissolve hydroxyapatite at peri-lacunar bone matrix. However, robust three-dimensional evidence for peri-canalicular bone mineral dissolution has been lacking. Here we applied a previously reported Talbot-defocus multiscan tomography method for synchrotron X-ray microscopy and analyzed the degree of bone mineralization in mouse cortical bone around the lacuno–canalicular network, which is connected both to blood vessels and the peri- and endosteum. We detected cylindrical low mineral density regions spreading around canaliculi derived from a subset of osteocytes. Transmission electron microscopy revealed both intact and demineralized bone matrix around the canaliculus. Peri-canalicular low mineral density regions were also observed in osteopetrotic mice lacking osteoclasts, indicating that osteoclasts are dispensable for peri-canalicular demineralization. These data suggest demineralization can occur from within bone through the canalicular system, and that peri-canalicular demineralization occurs not uniformly but directed by individual osteocytes. Blockade of peri-canalicular demineralization may be a therapeutic strategy to increase bone mass and quality.

Automatic Stem Mapping by Merging Several Terrestrial Laser Scans at the Feature and Decision Levels

Detailed up-to-date ground reference data have become increasingly important in quantitative forest inventories. Field reference data are conventionally collected at the sample plot level by means of manual measurements, which are both labor-intensive and time-consuming. In addition, the number of attributes collected from the tree stem is limited. More recently, terrestrial laser scanning (TLS), using both single-scan and multi-scan techniques, has proven to be a promising solution for efficient stem mapping at the plot level. In the single-scan method, the laser scanner is placed at the center of the plot, creating only one scan, and all trees are mapped from the single-scan point cloud. Consequently, the occlusion of stems increases as the range of the scanner increases, depending on the forest's attributes. In the conventional multi-scan method, several scans are made simultaneously inside and outside of the plot to collect point clouds representing all trees within the plot, and these scans are accurately co-registered by using artificial reference targets manually placed throughout the plot. The additional difficulty of applying the multi-scan method is due to the point-cloud registration of several scans not being fully automated yet. This paper proposes a multi-single-scan (MSS) method to map the sample plot. The method does not require artificial reference targets placed on the plot or point-level registration. The MSS method is based on the fully automated processing of each scan independently and on the merging of the stem positions automatically detected from multiple scans to accurately map the sample plot. The proposed MSS method was tested on five dense forest plots. The results show that the MSS method significantly improves the stem-detection accuracy compared with the single-scan approach and achieves a mapping accuracy similar to that achieved with the multi-scan method, without the need for the point-level registration.

Thermal Decomposition of Pyrite FeS&lt;sub&gt;2&lt;/sub&gt; under Reducing Conditions

The thermal decomposition of pyrite was investigated under reducing atmosphere, e.g. p(O2)~10-6 bar. Thermogravimetric measurements were coupled with differential scanning calorimetry and mass spectrometry. Multi-scan method was used to calculate the values of the activation energy of the reaction of thermal decomposition of the pyrite. It was shown that the value of the activation energy of the decomposition of pyrite into pyrrhotite varies with the reaction progress. The values of activation energy vary from 250 to 350 kJ.mol-1.

System and method for performing a three-dimensional virtual examination of objects, such as internal organs

Methods for generating a three-dimensional visualization image of an object, such as an internal organ, using volume visualization techniques are provided. The techniques include a multi-scan imaging method; a multi-resolution imaging method; and a method for generating a skeleton of a complex three dimension object. The applications include virtual cystoscopy, virtual laryngoscopy, virtual angiography, among others.

Performance of a multiscan track-to-track association technique

The formula for calculating the theoretical probability of false association for the technique of track-to-track association (TTTA) using multiscan data is presented. The multiscan TTTA technique and the singlescan TTTA technique are studied by analysis and simulation. The conclusion is that the theoretical performance of the multiscan method is better than that of the singlescan method; however the practical performance of the former evaluated in our simulation is much worse than its theoretical performance, yet could still be more or less better than that of the latter. The reason is that estimation errors of the sensor-level tracks are strongly dependent across time.

Multiscanning method for fabricating electron moiré grating

In this paper we present a multiscanning method for fabricating an electron moire grating. Many repeated scans are used, instead of a single scan. The resultant grating lines are the sum of these scans. Through this process, the grating error can be reduced from about 85% in the single-scanning method to below 5%. The experimental results show that a highly accurate grating can be fabricated in this way.

Performance of a multiscan track-to-track association technique

The formula for calculating the theoretical probability of false association for the technique of track-to-track association (TTTA) using multiscan data is presented. The multiscan TTTA technique and the single-scan TTTA technique are studied by analysis and simulation. The conclusion is that the theoretical performance of the multiscan method is better than that of the single-scan method; however the practical performance of the former evaluated in our simulation is much worse than its theoretical performance, yet could still be more or less better than that of the latter. The reason is that estimation errors of the sensor-level tracks are strongly dependent across time.

マルチスキャン法を用いた導電性セラミックスの熱電測定

A measurement of the thermoelectric property of conductive ceramics by multi-scan method was developed. The conductive boride composite ceramics (104 S) with a size of 2×3×15mm was used in this experiment. The electorical conductivity and Seebeck coefficient at high temperature by multi-scan method were carried out in an electric furnace in an argon gas atmosphere at room temperature to 1073K. A rapid and accurate measurement of the Seebeck coefficient was performed by multi-scan method. The time needed for each measurement was less than a few fiftys of seconds, significantly shorter with accuracy than for a conventional do method.

Compositing 3D images with antialiasing and various shading effects

A method is proposed for compositing 3-D images produced by different programs, taking depth order into consideration. The method can add the following effects to composited images: antialiased images with scaling are displayed by a simple algorithm; the algorithm can add shading effects due to various types of light, such as area sources and skylight; and ray tracing can be performed in localized regions, producing realistic results without the computational expense of ray tracing the whole image. In addition to the above processes, such shading effects as fog and texture mapping can be processed with conventional methods. Thus, it becomes possible to display complex scenes with various shading effects, using relatively small computers. The multiscanning method used for antialiasing and a data structure for processing it are described. Examples are presented to demonstrate the capability of the system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Multiple crystal cross-sectional echocardiography in the diagnosis of cyanotic congenital heart disease.

A new multiple crystal echocardiographic system was used to assess cross-sectional cardiac anatomy in real time in fifty infants and children with cyanotic heart disease, and the findings were compared to normals. Four standard transducer positions were employed to evaluate sagittal and transverse cardiac cross-sections. Studies in patients with tetralogy of Fallot demonstrated an enlarged aorta overriding the septum with preservation of mitral-aortic continuity. In the absence of pulmonary atresia the main pulmonary artery could be identified in all of these patients. The diagnosis of d -transposition of the great vessels was established by viewing great vessel orientation in transverse section at the second intercostal space and observing a rightward and anteriorly placed great artery. In sagittal projections a retrosternal aorta and mitral-pulmonic continuity was observed. In one patient with d -transposition, apposition in systole of the ventricular septum and anterior leaflet of the mitral valve was identified as the cause of left ventricular outflow tract obstruction. Descriptions are provided of the findings in patients with l -transposition, double outlet right ventricle, and truncus arteriosus. The new multiscan method allows a substantially more precise determination of intra- and extra-cardiac spatial relationships than single crystal techniques. Multiscan echocardiography is safe, widely applicable, and provides clinically important information to assist in the diagnosis and management of infants and children with cyanotic heart disease.