Scanning Operation Research Articles

무선랜에서 주기적인 채널탐색이 TCP 처리율에 미치는 영향

In this paper, we address the TCP-over-WLAN performance problem that occurs during periodic active background scanning with which mobile devices discover available APs in the vicinity. We measure the impact of the scanning period on the TCP throughput and observe a significant performance degradation when the scan operation period is shortened. Our experimental analysis has identified the main cause of the problem, that is, the associated AP continues to send packets to the mobile device even when the device is not able to receive due to the scanning operation.

Closed-loop Process Control for Laser Patterning of Thin Film Strain Sensors

This work presents a laser based bridge balancing method for strain sensor circuits which are applied directly on component surfaces by means of thin film deposition and laser patterning. The balancing process is integrated in the patterning process and consists of iterative cycles of laser scanning and bridge measurement operations until a balanced bridge circuit is generated. It is shown that a balanced bridge circuit on the surface of a non-planar surface can be generated within few scan cycles, and thus, allows for short processing times and high-throughput manufacturing of integrated thin film strain sensors on the surface of mechanical components.

The application of mastoidoplasty in repeated scanning operations on the ear

The objective of the present study was to evaluate the outcomes of mastoid obliteration with the use of the orthotopic bone tissue taken from the linea temporalis region. It was shown that this region is the optimal site at the temporal bone for the harvesting of the plastic bone material to be used in mastoidoplasty during secondary sanitizing surgical interventions on the patients with mastoid cavity problems after canal wall-down mastoidrctomy under conditions of the deficiency of the orthotopic bone tissue. The application of such tissue for the purpose of mastoid-obliteration surgery provides a number of advantages over other methods of mastoidoplasty, in the first place from the standpoint of tissue biocompatibility. Multispiral computed tomography (MSCT) of the temporal bones is a highly informative and non-invasive technique for the study and control of the patients' condition during the late postoperative period following a secondary sanitizing surgical intervention involving mastoidoplasty with the application of the orthotopic bone tissue.

Modeling and Control of a Large-Stroke Electrothermal MEMS Mirror for Fourier Transform Microspectrometers

A microelectromechanical systems (MEMS) mirror with large vertical displacement has been developed for Fourier transform microspectrometers, but there exists a large tilting during the large-stroke scanning of the MEMS mirror, which greatly compromises the usable range. In this paper, a closed-loop control method has been established to minimize the tilting of the MEMS mirror. According to experimental results, the tilting motion of the mirror plate can be modeled as a fourth-order system. A feedback controller consisting of a phase-lag compensator, a low-pass filter and a notch filter utilized to stabilize the closed-loop tilt system. A gain scheduling approach is also used to compensate the bias-dependent loop gain and thereby provide more consistent tilting rejection over a wide scan range. Compared with the open-loop drive approach, the closed-loop system offers a stable scan operation with much faster dynamic response and improved overall robustness. The experiments show that the residual tilting is reduced to below ±0.0015° during the full range scan of the MEMS mirror. With this control method, the MEMS mirror achieved a stable scan range up to 356.4 $\mu \text{m}$ , so the measured spectral resolution reached 28 nm at 532 nm in a microspectrometer. The mirror tilting can be reduced dramatically by the proposed active control scheme, and thereby, the usable vertical scan range is increased significantly. [2016-0061]

Динамическая компиляция выражений в SQL-запросах для СУБД PostgreSQL

In recent years, as performance and capacity of main and external memory grow, performance of database management systems (DBMSes) on certain kinds of queries is more determined by raw CPU speed. Currently, PostgreSQL uses the interpreter to execute SQL queries. This yields an overhead caused by indirect calls to handler functions and runtime checks, which could be avoided if the query were compiled into native code on-the-fly, i.e. just-in-time (JIT) compiled: at run time the specific table structure is known as well as data types and built-in functions used in the query as well as the query itself. This is especially important for complex queries, performance of which is CPU-bound. We’ve developed a PostgreSQL extension that implements SQL query JIT compilation using LLVM compiler infrastructure. In this paper we show how to implement JIT compilation to speed up sequential scan operator (SeqScan) as well as expressions in WHERE clauses. We describe some important optimizations that are possible only with dynamic compilation, such as precomputing tuple attributes offsets only for attributes used by the query. We also discuss the maintainability of our extension, i.e. the automation for translating PostgreSQL backend functions into LLVM IR, using the same source code both for our JIT compiler and the existing interpreter. Currently, with LLVM JIT we achieve up to 5x speedup on synthetic tests as compared to original PostgreSQL interpreter.

Keyframe-based video mosaicing for historical Ottoman documents

Image mosaicing is a trendy research area in computer vision in recent years. Instead of images, video frames can be mosaiced to form a larger aggregate. In both cases, merging computations generally depend on the common parts in consecutive images, which are called overlapping regions. The presence of mobile devices with a camera provides higher image and video acquisition; hence video mosaicing techniques can be utilized to digitize and to create high resolution historical document images for later use in browsing and retrieval systems. Here, we present a technique to create high resolution images of historical Ottoman documents from video. The video captures the frames while tracing the document in row major ordering. In the preprocessing steps, the frames are oriented automatically by the help of tracking the optical flow, and the keyframes are selected such that a sufficient overlapping region in between is guaranteed. Then the scanning phase traces these keyframes in horizontal and vertical manner to create the final video mosaic image in higher resolution. Both horizontal and vertical scan operations utilize a distance vector to compute similarity between two adjacent images. The effectiveness of the video mosaicing approach for historical Ottoman documents is evaluated, and the results of the experiments show that the approach is expressive yet effective to create high resolution Ottoman images.

Broadly available imaging devices enable high-quality low-cost photometry.

This paper demonstrates that, for applications in resource-limited environments, expensive microplate spectrophotometers that are used in many central laboratories for parallel measurement of absorbance of samples can be replaced by photometers based on inexpensive and ubiquitous, consumer electronic devices (e.g., scanners and cell-phone cameras). Two devices, (i) a flatbed scanner operating in transmittance mode and (ii) a camera-based photometer (constructed from a cell phone camera, a planar light source, and a cardboard box), demonstrate the concept. These devices illuminate samples in microtiter plates from one side and use the RGB-based imaging sensors of the scanner/camera to measure the light transmitted to the other side. The broadband absorbance of samples (RGB-resolved absorbance) can be calculated using the RGB color values of only three pixels per microwell. Rigorous theoretical analysis establishes a well-defined relationship between the absorbance spectrum of a sample and its corresponding RGB-resolved absorbance. The linearity and precision of measurements performed with these low-cost photometers on different dyes, which absorb across the range of the visible spectrum, and chromogenic products of assays (e.g., enzymatic, ELISA) demonstrate that these low-cost photometers can be used reliably in a broad range of chemical and biochemical analyses. The ability to perform accurate measurements of absorbance on liquid samples, in parallel and at low cost, would enable testing, typically reserved for well-equipped clinics and laboratories, to be performed in circumstances where resources and expertise are limited.

Time-efficient interleaved human (23)Na and (1)H data acquisition at 7 T.

The aim of this study was to implement and evaluate a flexible and time-efficient interleaved imaging approach for the acquisition of proton and sodium images of the human knee at 7 T within a clinically relevant timescale. A flexible software framework was established which allowed the interleaving of multiple, different, fully specific absorption ratio (SAR)-validated scans. The system was able to switch between these different scans at flexible time points. The practical example presented consists of interleaved proton (Dixon imaging and T2* mapping) and sodium (mapping the sodium content and fluid-suppressed component separately) sequences with the key idea to perform proton MRI whilst the sodium nuclei relax towards thermal equilibrium, and vice versa. Comparisons were made between these four scans being acquired sequentially in the normal mode of scanner operation and those acquired in an interleaved fashion. Images acquired in the interleaved mode were very similar to those acquired in sequential scans with no image artifacts produced by the slight intra-sequence variation in steady-state magnetization. A reduction in scanning time of almost a factor of two was established using the interleaved scans, allowing such a protocol to be completed within 30 min. Phantom experiments and in vivo scans performed in healthy volunteers and in one patient proved the basic feasibility of this approach. This approach for the interleaving of multiple proton and sodium scans, each with different contrasts, is an efficient method for the design of new practical clinical protocols for sodium MRI.

The Influence of Electric Parameters on Film Quality of GZO Thin Film Fabricated by APPJ Process

In this paper, APPJ (Atmospheric pressure Pules arc Plasma Jet) is used to generate a DC pulse source depositing GZO thin film under atmospheric pressure. Thus, no vacuum chamber needed leads to the cost downward. With scanning operation, makes single unit area into large size area. Several key process parameters have been studied, including the power supply voltage, DC pulse, the length of the nozzle extended head, and depositing gap to understand their relationship with the film quality and atmospheric plasma state.In this study, with adjusting DC pulse, the pulse frequency is found to have a great impact on the plasma state and the film quality. When the pulse frequency is near 25 kHz, lower sheet resistance can be retained. Besides, adjusting Toff time, the plasma and thin film quality are influenced more than Ton time. By changing the power supply voltage, the secondary-side voltage decreases with increasing of the instantaneous current; moreover, the plasma will become more intense.

Fast LH $$*$$ ∗

Linear Hashing is an efficient and widely used version of extendible hashing. LH$$*$$ź is its distributed version that stores key-value pairs on up to hundreds of thousands of sites in a distributed system. LH$$*$$ź implements the dictionary data structure efficiently by not using a central component and allows the key-based operations of insertion, deletion, actualization, and retrieval as well as the scan operation. Because it does not use a central addressing component, clients or servers in LH$$*$$ź can commit an addressing error by sending a request to a wrong server. This server then forwards the message to the correct server either directly or in one but never more than one additional forward operation. We discuss here methods to avoid this double forward, which, while rare, still might breach quality of service guarantees. We compare our methods with $$\mathrm{LH}*_{\mathrm{RS}^{\mathrm{\tiny P2P}}}$$LHźRSP2P that pushes information about changes in the file structure to clients, whether they are active or not. A second problem especially relevant in high churn environments such as modern data centers is that sites can suddenly become inaccessible. The various high and scalable reliability versions of LH$$*$$ź then reconstruct the data lost on this site elsewhere. We present a solution to the resulting "wandering bucket" problem that allows clients to find the data at their new location.

Automatic Channel Fault Detection and Diagnosis System for a Small Animal APD-Based <newline/>Digital PET Scanner

Fault detection and diagnosis is critical to many applications in order to ensure proper operation and performance over time. Positron emission tomography (PET) systems that require regular calibrations by qualified scanner operators are good candidates for such continuous improvements. Furthermore, for scanners employing one-to-one coupling of crystals to photodetectors to achieve enhanced spatial resolution and contrast, the calibration task is even more daunting because of the large number of independent channels involved. To cope with the additional complexity of the calibration and quality control procedures of these scanners, an intelligent system (IS) was designed to perform fault detection and diagnosis (FDD) of malfunctioning channels. The IS can be broken down into four hierarchical modules: parameter extraction, diagnosis, channel fault detection and fault prioritization. Of these modules, parameter extraction and fault detection have previously been reported and this paper focuses on diagnosis, improved fault detection and fault prioritization. The status diagnosis module will diagnose all channels and propose an explanation of the reasons that lead to the diagnosis. The purpose of the fault prioritization module is to help the operator to zero in on the faults that need immediate attention. The FDD system was implemented on a LabPET avalanche photodiode (APD)-based digital PET scanner. Experiments demonstrated a FDD Sensitivity of 99.9% (with a 95% confidence interval (CI) of [99.6, 100.0]) for major faults. Globally, the balanced accuracy of the diagnosis for varying fault severities is 91%. This suggests the IS can greatly benefit the operators in their maintenance task.

Examining Deep Convective Cloud Evolution Using Total Lightning, WSR-88D, and GOES-14 Super Rapid Scan Datasets*

Abstract The Geostationary Operational Environmental Satellite-14 (GOES-14) Imager operated in 1-min Super Rapid Scan Operations for GOES-R (SRSOR) mode during summer and fall of 2012 to emulate the high temporal resolution sampling of the GOES-R Advanced Baseline Imager (ABI). The current GOES operational scan interval is 15–30 min, which is too coarse to capture details important for severe convective storm forecasting including 1) when indicators of a severe storm such as rapid cloud-top cooling, overshooting tops, and above-anvil cirrus plumes first appear; 2) how satellite-observed cloud tops truly evolve over time; and 3) how satellite cloud-top observations compare with radar and lightning observations at high temporal resolution. In this paper, SRSOR data, radar, and lightning observations are used to analyze five convective storms, four of which were severe, to address these uncertainties. GOES cloud-top cooling, increased lightning flash rates, and peak precipitation echo tops often preceded severe weather, signaling rapid intensification of the storm updraft. Near the time of several severe hail or damaging wind events, GOES cloud-top temperatures and radar echo tops were warming rapidly, which indicated variability in the storm updraft that could have allowed the hail and wind gusts to reach the surface. Above-anvil cirrus plumes were another prominent indicator of impending severe weather. Detailed analysis of storms throughout the 2012 SRSOR period indicates that 57% of the plume-producing storms were severe and 85% of plumes from severe storms appeared before a severe weather report with an average lead time of 18 min, 9 min earlier than what would be observed by GOES operational scanning.

A rotating scan scheme for automatic outlier removal in laser scanning of reflective surfaces

Outlier removal is a fundamental and critical data processing task so as to ensure quality of scanned point clouds and their applications. Point clouds collected from reflective surfaces are often contaminated by extensive outliers. Existing outlier removal methods usually rely on analyzing the point cloud data only without the knowledge of outlier formation and the information of the scanning operation. They generally show limited effectiveness in detecting the extensive outliers. This paper aims to utilize the outlier formation characteristics in relation to scanning orientations in order to develop an effective outlier removal approach. It is observed that the regions where outliers occur are generally dependent on the scanning orientation whereas ordinary scanned surface points are almost invariant regardless of the scanning orientation. An outlier removal method based on a rotating scan scheme is proposed to detect such view-dependent outliers. The key feature of the rotating scan scheme is to utilize the scanning orientation information together with the raw scanned point clouds to reliably detect outliers. Numerous case studies have been conducted to demonstrate the effectiveness of the proposed rotating scan scheme in comparison with various existing methods.

Next viewing directions for the scanning of dental impressions

This paper proposes a scanning procedure for a structured light system (SLS) to measure dental impressions. Although increasing the number of scanning orientations may improve the quality of a scanned model, it is desirable to minimize the number of scanning operations to time and data storage. We attempt to reduce the number of scanning operations to the least number that will still acquire a complete model. The proposed procedure must resolve two sub-problems: (1) identification of missing areas from given range images, and (2) determination of the next viewing directions to fill those missing areas. If we consider range images as triangular meshes, the sub-problems can be solved by using well-known geometric algorithms. The triangular meshes, however, may consist of tens of millions of triangles, which require an unacceptably long time to compute. To cope with this problem, we propose two key ideas: (1) utilizing an inherent attribute of a range image, the map structure; (2) utilizing a graphics board to accelerate the evaluation of visibility. Our demonstration proves that the proposed approach improves the quality of scanned models and reduces the number of scanning operations.

A hierarchical model for automated standard sagittal-view detection from 3D ultrasound data in 11–14 weeks

The nuchal translucency thickness is an important parameter for the diagnosis of fetal abnormalities during 11–14 weeks. Currently in clinical practice, it first requires manual scanning operations to determine the fetal standard sagittal-view plane and then the measurements can be performed in the corresponding plane images. Besides the difficulty of such standard plane detection, this also leads to the time-consuming and detection-variability problems. In the paper, a hierarchical model is proposed to automatically detect the standard sagittal-view plane based on 3D ultrasound data. In the model, Hessian-matrix based filtering is first applied for obtaining the plate-structure distribution in the data. Then the sphere distribution is calculated by convolving sphere detectors with the ultrasound data. Based on the two prior distributions, the sampling-based Hough transform is further performed for the plane detection. The performance of the proposed model is verified by the experimental results on 3D synthetic data and 241 clinical 3D ultrasound data in 11–14 weeks.

Rapid Refresh Information of Significant Events: Preparing Users for the Next Generation of Geostationary Operational Satellites

Abstract The Geostationary Operational Environmental Satellite-14 (GOES-14) imager was operated by the National Oceanic and Atmospheric Administration (NOAA) in an experimental rapid scan 1-min mode during parts of the summers of 2012 and 2013. This scan mode, known as the super rapid scan operations for GOES-R (SRSOR), emulates the high-temporal-resolution sampling of the mesoscale region scanning of the Advanced Baseline Imager (ABI) on the next-generation GOES-R series. This paper both introduces these unique datasets and highlights future satellite imager capabilities. Many phenomena were observed from GOES-14, including fog, clouds, severe storms, fires and smoke (including the California Rim Fire), and several tropical cyclones. In 2012 over 6 days of SRSOR data of Hurricane Sandy were acquired. In 2013, the first two days of SRSOR in June observed the propagation and evolution of a mid-Atlantic derecho. The data from August 2013 were unique in that the GOES imager operated in nearly continuous 1-min mode; prior to this time, the 1-min data were interrupted every 3 h for full disk scans. Used in a number of NOAA test beds and operational centers, including NOAA’s Storm Prediction Center (SPC), the Aviation Weather Center (AWC), the Ocean Prediction Center (OPC), and the National Hurricane Center (NHC), these experimental data prepare users for the next-generation imager, which will be able to routinely acquire mesoscale (1,000 km × 1,000 km) images every 30 s (or two separate locations every minute). Several animations are included, showcasing the rapid change of the many phenomena observed during SRSOR from the GOES-14 imager.

Limited-Use Atomic Snapshots with Polylogarithmic Step Complexity

This article presents a novel implementation of a snapshot object for n processes, with O (log 2 b log n ) step complexity for update operations and O (log b ) step complexity for scan operations, where b is the number of updates. The algorithm uses only reads and writes. For polynomially many updates, this is an exponential improvement on previous snapshot algorithms, which have linear step complexity. It overcomes the existing Ω( n ) lower bound on step complexity by having the step complexity depend on the number of updates. The key to this implementation is the construction of a new object consisting of a pair of max registers that supports a scan operation.

Phase-spacing optimization of linear microstrip antenna arrays using simulation-based surrogate superposition models

A technique for simulation-driven optimization of the phase excitation tapers and spacings for linear arrays of microstrip patch antennas is presented. Our technique exploits two models of the array under optimization: an analytical model which is based on the array factor, as well as an electromagnetic (EM) simulation-based surrogate model of the entire array. The former is used to provide initial designs which meet the design requirements imposed on the radiation response. The latter is used for tuning of the array radiation response while controlling the array reflection response as well as for validation of the final design. Furthermore, the simulation-based surrogate model allows for subsequent evaluation of the array responses in the beam scanning operation at negligible computational costs. The simulation-based surrogate model is constructed with a superposition of simulated radiation and reflection responses of the array under design with only one radiator active at a time. Low computational cost of the surrogate model is ensured by the EM-simulation data computed with coarse meshes. Reliability of the model is achieved by means of suitable correction carried out with respect to the high-fidelity array model. The correction is performed iteratively in the optimization process. Performance, numerical efficiency, and accuracy of the technique is demonstrated with radiation pattern synthesis of linear arrays comprising 32 microstrip patch antennas by phase-spacing optimization. Properties of the optimal designs in the beam scanning operation are then studied using the superposition models and compared to suitably selected reference designs. The proposed technique is versatile as it also can be applied for simulation-based optimization of antenna arrays comprising other types of individually fed elements. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:536–547, 2015.

0203 Reduction of Measurement Error Induced by Laser Speckles in Scanning Operations using a Triangulation-based Laser displacement Sensor

0203 Reduction of Measurement Error Induced by Laser Speckles in Scanning Operations using a Triangulation-based Laser displacement Sensor

Study of Double-strangeness Nuclear Systems with Nuclear Emulsion

Double strangeness nuclei such as double-Λ and Ξ hypernuclei have been studied with nuclear emulsion due to its fine position resolution. Recently, we have started an experiment to study Λ-Λ interaction more accurately than that information given by the NAGARA event with ∼102 double-Λ hypernuclei which may provide us understanding free from nuclear medium effect. It is necessary to develop treatment method for huge amount, 2.1 tons of the emulsion gel, even if very pure K− beams are available at J-PARC. We have developed the base film to support the emulsion, emulsion surface coating method with a special layer of 0.5μm thick, method for making large-size plate (35.0 x 34.5 cm2) and scanning method, called “overall scanning”. The first evidence of a deeply bound state of Ξ--14N system, named KISO, was successfully detected in the test operation of the overall scanning.