查看更多>>摘要：The existing calibration methods of line-structured light system have complicated calibration procedures. To address this issue, this paper presents a practicable calibration method based on a homography matrix. In this calibration method, it does not need the camera calibration as well as the light plane calibration. First, a sequence of the light-stripe images and sinusoidal fringe images are obtained at different positions moved by a translation stage. Second, a series of feature points located at the light plane will be extracted from these images. Then, a homography matrix, which is to map the relationship between the light plane and the image plane, can be calculated. The three-dimensional (3D) data of a tested object can be restored by this matrix after extracting the image coordinates of the light-stripe images. The experimental results have shown its feasibility and validity. Moreover, the entire calibration process is practicable to simplify the experimental procedures and easy to be applied in industrial inspection.
查看更多>>摘要：In this paper, the geometry structure, electronic structure and optical properties of TiO2-anatase, TiO2-anatase doped with N and TiO2-anatase doped with N/P atoms were investigated by the plane-wave ultrasoft pseudopotential method based on the first-principles density functional theory. It demonstrates that there exist additional states in the band gap as TiO2-anatase was doped with N and TiO2-anatase was doped with N/P atoms, and the band gap narrows. The conduction band and valence band position of TiO2-anatase doped with N/P move to lower energy levels, that enhance the ability of oxidation and reduction, which is conducive to improve the photocatalytic performance. Red shift phenomenon, oxygen vacancies increase and enhanced photocatalytic properties of TiO2-anatase doped with N/P has been found by XRD, IR, RRS optical spectrum of the N/P doped TiO2- anatase, which verify our theory analysis.
查看更多>>摘要：Diffuse optical tomography (DOT) is an optical imaging technique using near-infrared spectroscopy (NIRS). Because the NIR light is highly scattered in biological tissue, the photon density drops rapidly with increasing depth. This makes the measurement accuracy of DOT in deep tissue significantly lower than in superficial tissue. Classical Regularized Least Square (RLS) based regularization methods with different penalty term (l1-norm, l2-norm, LASSO, Ridge, and Elastic Net etc.) come up short in finding the inclusions when the inclusion number is increased or one of the inclusion located on the upper surface and the other one located on the deeper surface of the tissue. This is the depth problem encountered in DOT. In this paper, a new least square based regularization method is proposed. Within the scope of the proposed method, both the weight matrix and penalty terms are modified in order to solve this problem. In this process, firstly, the A matrix is changed using the diagonal value of AA(T) based on DCA (Depth Compensation Algorithm). Then, a new penalty term using modified A matrix is added. It has been observed that when the noise level increases, proposed method give higher accuracy and more robust according to other RLS Method on synthetic data. Experimental results on synthetic data show that the new method improves inversion accuracy, reduces errors, and the lowers inversion instability compared to the state-of-the-art methods.
查看更多>>摘要：In this article, we describe the unified auxiliary equation method to obtain solutions with the help of the jacobi elliptic sine and cosine functions. We search for new solutions by applying this method to the dimensionless time-dependent Paraxial equation used in mathematical optics. We get the solutions found for the equation as jacobi elliptic, dark, singular solutions. Different solutions provide solid interpretation in different aspects of related subjects such as mathematical physics, mathematical optics. All solutions are verified by substituting them into the original equation with the help of computere software. Also, we provide graphs for some solutions.
查看更多>>摘要：Efficiency and denoising performance are two important indexes to objectively evaluate an image denoising method. Traditional model-based denoising methods usually pursue pleasing performance at the cost of highly computational complexity, while the popular deep learning-based methods perform well on efficiency improvement but still fail in rich structure preservation. To cope with these problems, this paper proposed a novel wavelet-based deep denoising methods, called as wavelet-based global-local filtering networks (WGLFNets). The WGLFNets includes the following three key points: First, an noisy image is decomposed into a base image and three-directional detail images by employing discrete wavelet transform (DWT). Second, the base component is denoised by a global denoising network while the detail components are recovered by a local detail restoration network. Finally, all processed components are utilized to construct the high-quality image by the inverse DWT (IDWT). Experimental results demonstrate that the WGLFNets is effective and is superior to the state-of-the-arts.
Yang, YuhuiLi, KeNawaz, Muhammad ZeeshanZhou, Mei...
14页
查看更多>>摘要：The ultimate goal of LED illumination-based multispectral imaging (LEDMSI) is higher image accuracy, more band spectrum information, and faster acquisition speed. The inherent square wave integral sampling mode limits the image accuracy and sampling speed of LEDMSI based frequency-division modulated with a sine wave as the carrier. A LED multispectral imaging combining square wave frequency-division modulation and camera external triggering is proposed. Experiments were conducted with five LEDs of different wavelengths and a monochrome camera as examples. The experimental design follows: the microprocessor generates a series of square waves whose frequency is twice the ratio relationship to modulate the light source of different wavelengths and control the camera to acquire synchronously. The camera sets the delay time and exposure time to acquire multispectral images synchronously. Then the single-band image is obtained through the differential accumulation algorithm. Use objective image quality evaluation indicators to evaluate the obtained images. The results show that this method can quickly acquire images of more wavelengths, maintain good image quality, and has good antiinterference ability, which provides a new idea for LEDMSI technology. The acquisition method is not limited to LEDMSI and the improved method can be widely used in signal acquisition systems with integration sampling mode.
查看更多>>摘要：The electronic structure, optical and thermoelectric properties of Janus T-phase SiSeS monolayer under biaxial strain have been analyzed using the first-principles calculations. Our calculations identified the Janus T-phase SiSeS monolayer as an indirect semiconductor with an energy band gap of 0.77 eV at the equilibrium state, which can be tuned effectively through a biaxial strain. The band gap tends to decrease slowly when the large compression biaxial strains are applied. It is of interest that a semiconductor-metal phase transition was obtained under biaxial compression strain of -8%. Moreover, the optical properties rise under biaxial strain with an enhanced absorption coefficient in the infrared region. Interestingly, the compressive biaxial strain combined with p-type doping in the Janus T-phase SiSeS monolayer produced a large electronic figure of merit (ZT(e)) of 7.0 at 300 K. The predicted results show the potential applications of Janus T-phase SiSeS monolayer for optoelectronic and thermoelectric devices.
查看更多>>摘要：A hybrid and robust digital image watermarking is suggested by using advantages of both fre-quency domain and wavelet domain. In this method, the most suitable color component of the host image and the most efficient wavelet sub-band are chosen, concluding from the compre-hensive experiments. In this paper, three parallel stages are used to embed and extract the watermark message. After transforming color component of the host image into the wavelet domain, some preprocessing with Discrete Cosines Transformers are applied, and then the watermark message is embedded into the best range by using a secret key. By detecting the rank of constructed detection matrices and voting among three output bits, the watermark bit is extracted. Simulation results demonstrate that the proposed method, besides the high robustness against Gaussian noise-based attacks especially AWGN, has performed well in imperceptibility and embedding capacity factors.
Zayed, Elsayed M. E.Alngar, Mohamed E. M.Shohib, Reham M. A.Nofal, Taher A....
9页
查看更多>>摘要：Objective: In our article, we deduce the soliton solutions for highly dispersive perturbed complex-Ginzburg-Landau equation in birefringent fibers having polynomial law of nonlinearity.& nbsp;Methods: In this study, we use two methods, namely the (G'/G)-expansion method and the addendum Kudryashov's method.& nbsp;Results: We have found the straddled, combo bright-singular, dark, bright and singular solitons solutions as long as the rational solutions of the proposed equation.
查看更多>>摘要：Rail flatness is an essential indicator of large rail components' quality, and is of great significance in inspecting the product quality of rail mills. The high-speed railways can only be built by rails with excellent flatness, while the standard ones are built by those with moderate defects in this respect. However, the rails must be straightened or discarded once the flatness are out of specific tolerances. In order to measure flatness, a gravitational straightedge method of adaptive two-end growth is proposed. This paper extracted the original flatness curve with a laser profilometer and calculated the maximum difference using the processing method for such curve. According to comparison of experimental data, the precision in repeatability was +/- 0.01 mm in such measurement conducted based on this algorithm, showing a difference of less than 0.02 mm compared with that achieved manually with a mechanical straightedge. Therefore, the algorithm was proved to be highly robust and accurate.
NSTL
Elsevier