Two-dimensional Pixel Research Articles

Principal component analysis to reduce dimension on digital image

High-resolution image is referred as high-dimensional data space as each image data is organized into two-dimensional pixel values in which each pixel consists of its respective RGB bits value. The representation of image data poses a challenge to sharing image files over Internet. The lengthy image uploading and downloading time has always been a major issue for Internet users. Apart from data transmission problem, high-resolution image consumes greater storage space. Principal Component Analysis (PCA) is a mathematical technique to reduce the dimensionality of data. It works on the principal of factoring matrices to extract the principal pattern of a linear system. This paper aims to evaluate the application of PCA on digital image feature reduction and compare the quality of the feature reduced images with difference variance values. As a result of summarizing the preliminary literature, dimension reduction process by PCA generally consists of four major steps: (1) normalize image data (2) calculate covariance matrix from the image data (3) perform Single Value Decomposition (SVD) (4) find the projection of image data to the new basis with reduced features. Experimental results showed that PCA technique effectively reduces the dimension of image data while still maintaining the principal properties of the original image. This technique achieved 35.3% for the file size reduction for the best feature reduced quality. The transmission time of image file over Internet has achieved significant improvement especially for the download activity via mobile devices.

A Multi-purpose Fingerprint Readout Circuit Embedding Physiological Signal Detection

A multi-purpose sensor interface that provides dual-mode operation of fingerprint sensing and physiological signal detection is presented. The dual-mode sensing capability is achieved by utilizing inter-pixel shielding patterns as capacitive amplifier’s input electrodes. A prototype readout circuit including a fingerprint panel for feasibility verification was fabricated in a 0.18 mm CMOS process. A single-channel readout circuit was implemented and multiplexed to scan two-dimensional fingerprint pixels, where adaptive calibration capability against pixel-capacitance variations was also implemented. Feasibility of the proposed multi-purpose interface was experimentally verified keeping low-power consumption less than 1.9 mW under a 3.3 V supply.

Calibration status and plans for the charge integrating JUNGFRAU pixel detector for SwissFEL

JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector under development for photon science applications at free electron laser and synchrotron facilities. In particular, JUNGFRAU detectors will equip the Aramis end stations of SwissFEL, an X-ray free electron laser currently under construction at the Paul Scherrer Institut in Villigen, Switzerland. JUNGFRAU has been designed specifically to meet the challenges of photon science at XFELs, including high frame rates, single photon sensitivity in combination with a high dynamic range, vacuum compatibility and tilable modules. This has resulted in a charge integrating detector with three dynamically adjusting gains, a low noise of 55 ENC RMS, readout speeds in excess of 2 kHz, single photon sensitivity down to 2 keV (with a signal to noise ratio of 10) and a dynamic range covering four orders of magnitude at 12 keV. Each JUNGFRAU module consists of eight chips of 256 × 256 pixels, each 75 × 75 μm2 in size. The chips are arranged in 2 × 4 formation and bump-bonded to a single silicon sensor 320 μm thick, resulting in an active area of approximately 4 × 8 cm2 per module. Multi-module vacuum compatible systems comprising up to 16 Mpixels (32 modules) will be used at SwissFEL. The design of SwissFEL and the JUNGFRAU system for the Aramis end station A will be introduced, together with results from early prototypes and a characterisation using the first batch of final JUNGFRAU modules. Plans and first results of the pixel-by-pixel calibration will also be shown. The vacuum compatibility of the JUNGFRAU module is demonstrated for the first time.

Structure of theAl13Co4(100) surface: Combination of surface x-ray diffraction andab initiocalculations

The structure of the quasicrystalline approximant ${\mathrm{Al}}_{13}{\mathrm{Co}}_{4}$(100) has been determined by surface x-ray diffraction (SXRD) and complementary density-functional-theory (DFT) calculations. Thanks to the use of a two-dimensional pixel detector, which speeds up the data acquisition enormously, an exceptionally large set of experimental data, consisting of 124 crystal truncation rods, has been collected and used to refine this complex structure of large unit cell and low symmetry. Various models were considered for the SXRD analysis. The best fit is consistent with a surface termination at the puckered type of planes but with a depletion of the protruding Co atoms. The surface energy of the determined surface model was calculated using DFT, and it takes a rather low value of $1.09\phantom{\rule{4pt}{0ex}}{\mathrm{J}/\mathrm{m}}^{2}$. The results for the atomic relaxation of surface planes found by SXRD or DFT were in excellent agreement. This work opens up additional perspectives for the comprehension of related quasicrystalline surfaces.

Elucidation of Reaction Mechanism at the Cathode/Electrolyte Interface in All-Solid-State Battery By Using Depth-Resolved X-Ray Absorption Spectroscopy

As one of the next-generation batteries, all-solid-state batteries have attracted a lot of attention due to their outstanding safety performance and energy density. However, their power performance are still far from traditional lithium ion batteries using liquid electrolyte, which is considered as a result of interfacial resistance existing between cathode and solid electrolyte. To overcome this inherent interfacial problem of all-solid-state batteries, there is an urgent need to understand the reaction mechanism at the cathode/electrolyte interface. As the origin of the interfacial resistance, so far there are three hypotheses have been proposed: the space-charge layer [1], the reaction product layer [2] and the mechanical structure change [3]. In this study, two types of LiCoO2 thin-film model electrodes with and without interface modification by using Li3PO4 interlayer were fabricated by pulsed laser deposition (PLD). The electrodes were applied for electrochemical measurement and depth resolved X-ray absorption spectroscopy (DR-XAS) measurement to investigate the reaction mechanism of interface between LiCoO2 cathode and Li2S-P2S5 solid electrolyte. In order to analyze the interfacial reaction, thin-film model electrode with LiCoO2 cathode and Li2S-P2S5 solid electrolyte was deposited on mirror-polished platinum substrate by PLD. A Li3PO4 interlayer was also deposited between cathode and solid electrolyte by PLD. Electrochemical measurements were performed by using liquid electrolyte (1M LiClO4 in propylene carbonate) and lithium metal anode. Cyclic voltammetry (CV) measurement was carried out from 3.2 V to 4.4 V at 0.1 mV/s. Electrochemical impedance spectroscopy (EIS) measurement was performed at 3.9 V, 4.0 V, 4.1 V, 4.2 V, 4.3 V and 4.4 V with a 30 mV amplitude during first charge and discharge cycle. The frequency range of EIS was limited from 10-2 to 106 Hz. DR-XAS measurements were conducted using the BL37XU beamline, SPring-8, Japan, with a two-dimensional pixel array detector, PILATUS (Dectris, Switzerland). Comparing to the thin-film electrode with Li3PO4 interlayer, the first cycle of CV curves of the electrode without Li3PO4 interlayer shows a current peak around 3.2 V, which is considered to come from the reaction between cathode and electrolyte. EIS measurements show that Li3PO4 interlayer can suppress the increase of interface resistant during charge and discharge, which means a more stable interface can be kept by interface modification. In order to make a more detailed observation of the interfacial structure, DR-XAS near edge structure of the electrodes are analyzed at Co K-edge. The energy shift around the interface in the electrodes with Li3PO4 interlayer is smaller than that of samples without Li3PO4 interlayer. These results indicate that valence changes of cobalt ions near cathode/solid electrolyte interface are suppressed by interface modification. The introducing of Li3PO4 interlayer reduces the inter-diffusion between cathode and solid electrolyte. The results of both electrochemical and DR-XAS measurements present that the reaction mechanism is the reaction product layer at cathode/electrolyte interface in all-solid-state battery using sulfide electrolyte. Reference [1] K. Takada, N. Ohta, L. Zhang, K. Fukuda, I. Sakaguchi, R. Ma, M. Osada, T. Sasaki , Solid State Ionics, 179 (2008) 1333. [2] A. Sakuda, A. Hayashi, M. Tatsumisago, Chem Mater, 22 (2010) 949. [3] K. Kishida, N. Wada, H. Adachi, K. Tanaka, H. Inui, C. Yada, Y. Iriyama, Z. Ogumi., Acta Materialia, 55 (2007) 4713. Acknowledgement This research was financially supported by the Japan Science and Technology Agency (JST), Advanced Low Carbon Technology Research and Development Program (ALCA), Specially Promoted Research for Innovative Next Generation Batteries (SPRING) Project.

Depth-Resolved X-Ray Absorption Spectroscopic Studies on Reaction Mechanism at the Cathode/Electrolyte Interface in All-Solid-State Battery

As one of the next-generation batteries, all-solid-state batteries have attracted attention due to their outstanding safety performance and energy density. However, their power performance are still far from the increasing demand of electric vehicles, which seems to be caused by the large interfacial resistance between cathode and solid electrolyte. To overcome the inherent interfacial problem of all-solid-state batteries, there is an urgent need to understand the reaction mechanism at the cathode/electrolyte interface. As the origin of the interfacial resistance, three hypotheses have been proposed: the space-charge layer [1], the reaction product [2] and the mechanical structure change [3]. In this study, we applied thin-film model electrode for electrochemical measurement and depth resolved X-ray absorption spectroscopy (DR-XAS) measurement to investigate the reaction mechanism of interface between LiCoO2 cathode and Li2S-P2S5 solid electrolyte with interface modification by using Li3PO4 interlayer. In order to analyze the interfacial reaction between cathode and electrolyte, thin-film model electrode with LiCoO2 cathode and Li2S-P2S5 solid electrolyte was deposited on mirror-polished platinum substrate by pulsed laser deposition (PLD). A Li3PO4 interlayer was also deposited between cathode and solid electrolyte by PLD. Electrochemical measurements were performed by using liquid electrolyte (1M LiClO4 in propylene carbonate) and lithium metal anode. Cyclic voltammetry measurement (CV) was carried out from 3.2 V to 4.4 V at 0.1 mV/s. EIS measurement was performed at 3.9 V, 4.0 V, 4.1 V, 4.2 V, 4.3 V and 4.4 V with a 30 mV amplitude. The frequency range of EIS was limited from 10-2 to 106 Hz. Depth-resolved XAS measurements were conducted using the BL37XU beamline, SPring-8, Japan, with a two-dimensional pixel array detector, PILATUS (Dectris, Switzerland). The first cycle of CV curves of the film without Li3PO4 interlayer shows a current peak around 3.2 V, which is considered to come from the reaction between cathode and electrolyte. EIS measurements show that the interfacial resistance of the films with Li3PO4 interlayer does not increase compared with the film without Li3PO4 interlayer. In order to discuss the interfacial structure, depth resolved X-ray near edge structure at Co K-edge is analyzed. The energy shift around the interface in the film with Li3PO4 interlayer is smaller than that of sample without Li3PO4 interlayer. These results indicate that valence changes of cobalt ions near cathode/solid electrolyte interface are suppressed by using Li3PO4 interlayer. The introducing of Li3PO4 interlayer reduces the inter-diffusion between cathode and solid electrolyte. Reference [1] K. Takada, N. Ohta, L. Zhang, K. Fukuda, I. Sakaguchi, R. Ma, M. Osada, T. Sasaki., Solid State Ionics, 179 (2008) 1333. [2] A. Sakuda, A. Hayashi, M. Tatsumisago., Chem Mater, 22 (2010) 949. [3] K. Kishida, N. Wada, H. Adachi, K. Tanaka, H. Inui, C. Yada, Y. Iriyama, Z. Ogumi., Acta Materialia, 55 (2007) 4713. Acknowledgement This research was financially supported by the Japan Science and Technology Agency (JST), Advanced Low Carbon Technology Research and Development Program (ALCA), Specially Promoted Research for Innovative Next Generation Batteries (SPRING) Project.

Towards hybrid pixel detectors for energy-dispersive or soft X-ray photon science.

JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications at free-electron lasers and synchrotron light sources. The JUNGFRAU 0.4 prototype presented here is specifically geared towards low-noise performance and hence soft X-ray detection. The design, geometry and readout architecture of JUNGFRAU 0.4 correspond to those of other JUNGFRAU pixel detectors, which are charge-integrating detectors with 75 µm × 75 µm pixels. Main characteristics of JUNGFRAU 0.4 are its fixed gain and r.m.s. noise of as low as 27 e(-) electronic noise charge (<100 eV) with no active cooling. The 48 × 48 pixels JUNGFRAU 0.4 prototype can be combined with a charge-sharing suppression mask directly placed on the sensor, which keeps photons from hitting the charge-sharing regions of the pixels. The mask consists of a 150 µm tungsten sheet, in which 28 µm-diameter holes are laser-drilled. The mask is aligned with the pixels. The noise and gain characterization, and single-photon detection as low as 1.2 keV are shown. The performance of JUNGFRAU 0.4 without the mask and also in the charge-sharing suppression configuration (with the mask, with a `software mask' or a `cluster finding' algorithm) is tested, compared and evaluated, in particular with respect to the removal of the charge-sharing contribution in the spectra, the detection efficiency and the photon rate capability. Energy-dispersive and imaging experiments with fluorescence X-ray irradiation from an X-ray tube and a synchrotron light source are successfully demonstrated with an r.m.s. energy resolution of 20% (no mask) and 14% (with the mask) at 1.2 keV and of 5% at 13.3 keV. The performance evaluation of the JUNGFRAU 0.4 prototype suggests that this detection system could be the starting point for a future detector development effort for either applications in the soft X-ray energy regime or for an energy-dispersive detection system.

Characterization results of the JUNGFRAU full scale readout ASIC

The two-dimensional pixel detector JUNGFRAU is designed for high performance photon science applications at free electron lasers and synchrotron light sources. It is developed for the SwissFEL currently under construction at the Paul Scherrer Institut, Switzerland. The detector is a hybrid pixel detector with a charge integration readout ASIC characterized by single photon sensitivity and a low noise performance over a dynamic range of 104 12 keV photons. Geometrically, a JUNGFRAU readout chip consists of 256×256 pixels of 75×75 μm2. The chips are bump bonded to 320 μm thick silicon sensors. Arrays of 2×4 chips are tiled to form modules of 4×8 cm2 area. Several multi-module systems with up to 16 Mpixels per system will be delivered to the two end stations at SwissFEL. The JUNGFRAU full scale readout ASIC and module design are presented along with characterization results of the first systems. Experiments from fluorescence X-ray, visible light illumination, and synchrotron irradiation are shown. The results include an electronic noise of ∼50 electrons r.m.s., which enables single photon detection energies below 2 keV and a noise well below the Poisson statistical limit over the entire dynamic range. First imaging experiments are also shown.

Broadband Carpet Cloak Designed using Nanocomposite Metamaterials for 3- 5��������Wavelength Range

In this paper, a broadband carpet cloak using nanocomposite layers to operate in whole 3–5-μm wavelength band is designed successfully. For this purpose, spherical nanometals or doped semiconductors with desired plasma frequency are proposed. In this way, the refractive index of the cloak as an analytic function is considered by optical conformal mapping. In a two-dimensional structure, we approximated the obtained refractive index inside each pixel to be constant. Each pixel is considered as an effective medium that possesses nanoparticles with desired plasma frequency. Therefore, plasma frequency of nanoparticles should be adjusted proportional to the desired value of refractive index in each two-dimensional pixels, which is approximated to be constant (two-dimensional layers approximation). The cloak region is compacted for broadband performance. To compact the cloak region, refractive index values should be greater than 1 and realization of these required values is possible by designing nonresonant structures.

Measurement of synchrotron-radiation-excited Kossel patterns.

Kossel line patterns contain information on the crystalline structure, such as the magnitude and the phase of Bragg reflections. For technical reasons, most of these patterns are obtained using electron beam excitation, which leads to surface sensitivity that limits the spatial extent of the structural information. To obtain the atomic structure in bulk volumes, X-rays should be used as the excitation radiation. However, there are technical problems, such as the need for high resolution, low noise, large dynamic range, photon counting, two-dimensional pixel detectors and the small spot size of the exciting beam, which have prevented the widespread use of Kossel pattern analysis. Here, an experimental setup is described, which can be used for the measurement of Kossel patterns in a reasonable time and with high resolution to recover structural information.

Radiation hardness assessment of the charge-integrating hybrid pixel detector JUNGFRAU 1.0 for photon science.

JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications in free electron lasers, particularly SwissFEL, and synchrotron light sources. JUNGFRAU is an automatic gain switching, charge-integrating detector which covers a dynamic range of more than 10(4) photons of an energy of 12 keV with a good linearity, uniformity of response, and spatial resolving power. The JUNGFRAU 1.0 application-specific integrated circuit (ASIC) features a 256 × 256 pixel matrix of 75 × 75 μm(2) pixels and is bump-bonded to a 320 μm thick Si sensor. Modules of 2 × 4 chips cover an area of about 4 × 8 cm(2). Readout rates in excess of 2 kHz enable linear count rate capabilities of 20 MHz (at 12 keV) and 50 MHz (at 5 keV). The tolerance of JUNGFRAU to radiation is a key issue to guarantee several years of operation at free electron lasers and synchrotrons. The radiation hardness of JUNGFRAU 1.0 is tested with synchrotron radiation up to 10 MGy of delivered dose. The effect of radiation-induced changes on the noise, baseline, gain, and gain switching is evaluated post-irradiation for both the ASIC and the hybridized assembly. The bare JUNGFRAU 1.0 chip can withstand doses as high as 10 MGy with minor changes to its noise and a reduction in the preamplifier gain. The hybridized assembly, in particular the sensor, is affected by the photon irradiation which mainly shows as an increase in the leakage current. Self-healing of the system is investigated during a period of 11 weeks after the delivery of the radiation dose. Annealing radiation-induced changes by bake-out at 100 °C is investigated. It is concluded that the JUNGFRAU 1.0 pixel is sufficiently radiation-hard for its envisioned applications at SwissFEL and synchrotron beam lines.

Estimation of noise properties for TV-regularized image reconstruction in computed tomography

A method for predicting the image covariance resulting from total-variation-penalized iterative image reconstruction (TV-penalized IIR) is presented and demonstrated in a variety of contexts. The method is validated against the sample covariance from statistical noise realizations for a small image using a variety of comparison metrics. Potential applications for the covariance approximation include investigation of image properties such as object- and signal-dependence of noise, and noise stationarity. These applications are demonstrated, along with the construction of image pixel variance maps for two-dimensional pixel images. Methods for extending the proposed covariance approximation to larger images and improving computational efficiency are discussed. Future work will apply the developed methodology to the construction of task-based image quality metrics such as the Hotelling observer detectability for TV-based IIR.

Efficient method for spaceborne synthetic aperture radar (SAR) geolocation and application to geometrical SAR image registration

An efficient method for spaceborne synthetic aperture radar (SAR) geolocation is devised in this study. In this method, the pixels in the SAR image are divided into two types by a two-dimensional (2D) grid, that is, grid pixels and non-grid pixels. The approach of finding the position of a non-grid pixel is to add the position of the adjacent grid pixel and the position increment between the two pixels together, where the position increment is computed by means of three groups of increment formulae derived according to the principle of first-order Taylor approximation. It is noticed that this method is efficient and helpful in improving the efficiency of the geometrical SAR image registration for avoiding the polynomial fitting and interpolation. In the geometrical registration, the 2D shifts of a non-grid pixel can be expressed as the sum of shifts of the adjacent grid pixel and shift increments between the two pixels. Here the position and 2D shifts of the grid pixel are obtained through the numerical methods for a complete lack of closed-form solutions. Finally, the experiments with TerraSAR-X images are conducted to evaluate the effectiveness of the proposed method.

JUNGFRAU 0.2: prototype characterization of a gain-switching, high dynamic range imaging system for photon science at SwissFEL and synchrotrons

JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional pixel detector for photon science applications at free electron lasers and synchrotron light sources. It is developed for the SwissFEL currently under construction at the Paul Scherrer Institute, Switzerland. Characteristics of this application-specific integrating circuit readout chip include single photon sensitivity and low noise over a dynamic range of over four orders of magnitude of photon input signal. These characteristics are achieved by a three-fold gain-switching preamplifier in each pixel, which automatically adjusts its gain to the amount of charge deposited on the pixel. The final JUNGFRAU chip comprises 256 × 256 pixels of 75 × 75 μm2 each. Arrays of 2 × 4 chips are bump-bonded to monolithic detector modules of about 4 × 8 cm2. Multi-module systems up to 16 Mpixels are planned for the end stations at SwissFEL. A readout rate in excess of 2 kHz is anticipated, which serves the readout requirements of SwissFEL and enables high count rate synchrotron experiments with a linear count rate capability of > 20 MHz/pixel. Promising characterization results from a 3.6 × 3.6 mm2 prototype (JUNGFRAU 0.2) with fluorescence X-ray, infrared laser and synchrotron irradiation are shown. The results include an electronic noise as low as 100 electrons root-mean-square, which enables single photon detection down to X-ray energies of about 2 keV. Noise below the Poisson fluctuation of the photon number and a linearity error of the pixel response of about 1% are demonstrated. First imaging experiments successfully show automatic gain switching. The edge spread function of the imaging system proves to be comparable in quality to single photon counting hybrid pixel detectors.

Efficient forward modelling using the self-consistent impedance method for electromagnetic surface impedance

The two-dimensional self-consistent impedance method is used to calculate the electromagnetic surface impedance above subsurface structures at very low frequencies. The method was derived from Faraday’s and Ampere’s Laws and results in a linear matrix equation where the right hand side of the equation corresponds to the source field introduced into the model as a fixed magnetic value. An air layer above the earth’s surface is included to allow the scattered magnetic field to be calculated at the surface. The source field is applied above the earth’s surface as a Dirichlet boundary condition, and a Neumann boundary condition is applied to all other boundaries in the solution space. The left hand side of the linear equation corresponds to the impedance matrix determined by discretising the solution space into two-dimensional rectangular pixels or cells bounded by lumped impedance elements, with values determined by the electromagnetic properties of the local media and the size of the pixel in the model. The resulting sparse matrix offers the flexibility of cells of any shape or size. Due to the large matrix dimensions, an iterative solver with a preconditioning technique was used to improve the speed, size and convergence of the solution. The efficient forward modelling has been applied to the analysis of a coal seam with various structural anomalies and line of oxidation along a line defined by 500 m with 0.5 m resolution. This improved technique allows in-field inverse modelling of surface impedance data. This paper reports several likely coal-seam scenarios relevant to surface mining operations.

A quick laboratory X-ray reflectometer for time-resolved observations

The measurement of the X-ray reflectivity curve is a widely used method to obtain structural information about thin films, surfaces and interfaces. With conventional instruments, the reflectivity curve is measured sequentially for a range of incident angles, which takes a long time. A recently developed method using white synchrotron radiation can measure the whole curve at once [1, 2]. In this contribution, the adaption of this method to a laboratory characteristic X-ray source is presented. This will make it possible to do time-resolved or high-throughput measurements using standard laboratory sources. The basic idea of our method is to focus the divergent X-ray beam emitted from a point source with either a doubly-curved Si crystal monochromator or a bent-twisted Si crystal monochromator [1]. Instead of using the whole beam, however, only the fan-shaped beam from a diagonal line on the monochromator is focused onto the sample. This is realized by placing an inclined slit before the monochoromator. The beam reflected from the sample forms a line on a two-dimensional pixel array detector. For each horizontal position on the detector, the incident angle onto the sample, and therefore the momentum transfer, is different. The reflectivity curve for a range of momentum transfers can therefore be measured with a single detector exposure without moving the sample, monochromator or detector. Reflectivity curves from a silicon wafer sample measured by our method are compared with the conventional angle scan method in the figure. The reflectivity down to 10 to the -7th power can be obtained, because the background can be subtracted from the measured intensity. We will show an example of time-resolved (10 s) measurements of specular X-ray reflectivity curves. We will also discuss the momentum transfer range that can be measured simultaneously and factors limiting the resolution of the method.

Two-Dimensional 8/9 Error Correcting Modulation Code

In holographic data storage (HDS), a high transmission rate is accomplished through the use of a charge coupled device array for reading two-dimensional (2D) pixel image data. Although HDS has many advantages in terms of storage capacity and data transmission rates, it also features problems, such as 2D intersymbol interference (ISI) by neighboring pixels and interpage interference (IPI) by multiple images stored in the same holographic volume. Modulation codes can be used to remove these problems. We introduce a 2D 8/9 error-correcting modulation code. The proposed modulation code exploits the trellis-coded modulation scheme, and the code rate is larger (about 0.889) than that of the conventional 6/8 balanced modulation code (an increase of approximately 13.9%). The performance of the bit error rate (BER) with the proposed scheme was improved compared with that of the 6/8 balanced modulation code and the simple 8/9 code without the trellis scheme.

In-house simultaneous collection of small-angle X-ray scattering, wide-angle X-ray diffraction and Raman scattering data from polymeric materials

An in-house X-ray scattering system, which can simultaneously measure small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) data, as well Raman scattering data, has been developed to study the phase transitions of polymeric materials. To date, these types of measurements have been limited to synchrotron radiation. The present system is an in-house SAXS system combined with a WAXD detector and a Raman spectrometer. A rotating-anode X-ray generator and multilayer optic are employed to provide a high-flux X-ray beam. Two two-dimensional hybrid pixel detectors are utilized for the rapid-scan time-resolved SAXS and WAXD measurements. The Raman unit consists of a compact probe with a near-infrared excitation laser operating at a wavelength of 1064 nm. This long-wavelength laser produces less fluorescence than conventional excitation lasers with wavelengths of 532 or 785 nm. The performance of this system was tested by investigating the thermally induced ferroelectric phase transition of vinylidene fluoride–trifluoroethylene (VDF-TrFE) copolymers. It has been demonstrated that the combination of SAXS, WAXD and Raman techniques gives useful information for revealing the relationship between the structural change in the crystal lattice and the morphological change in the lamellar stacking mode in polymer samples of complicated hierarchical structure.

The Application of Remote Image Optimization Delivery Technology in Online Education

In online education, the three-dimensional image is transmitted remotely via the network, the amount of information contained in a three-dimensional image is higher than the two-dimensional pixel, reconstruction is also more complex than the two-dimensional, once interference is present, the three-dimensional features of image lost. To avoid these shortcomings, an anti-interference transmission method based on new remote image network is presented for online education. Image enhancement method is applied to strengthen the contents of the image, and support vector machine method is utilized to optimize the compression process of wavelet coefficients, and ensure low-loss compression. Experimental results show that the algorithm benefits remote network education in transmitting three-dimensional image to the terminal accurately and the image compression losses are reduced.

Error-Correcting 7/9 Modulation Codes For Holographic Data Storage

Holographic data storage (HDS) has a number of advantages, including a high transmission rate through the use of a charge coupled device array for reading two-dimensional (2D) pixel image data, and a high density capacity. HDS also has disadvantages, including 2d intersymbol interference by neighboring pixels and interpage interference by multiple pages stored in the same holographic volume. These problems can be eliminated by modulation codes. We propose a 7/9 error-correcting modulation code that exploits a Viterbi-trellis algorithm and has a code rate larger (about 0.778) than that of the conventional 6/8 balanced modulation code. We show improved performance of the bit error rate with the proposed scheme compared to that of the simple 7/9 code without the trellis scheme and the 6/8 balanced modulation code.