Dual-Gratings Imaging Spectrometer

Common dispersive-type spectroscopic instruments include prism-type and grating-type, usually using a single dispersive element. The continuous imaging band is always limited by the dispersion angle. When it is necessary to image two wavebands with an ultra-spectral resolution that are far apart, the imaging is difficult due to the large diffraction angle. To broaden the spectral coverage of the imaging spectrometer, in this paper, we propose a dual-gratings imaging spectrometer with two independently rotating gratings. In this proposed system, two very far apart wavelength bands can be imaged in the adjacent areas by adjusting the angle of the dual gratings. This greatly expands the spectral coverage of the imaging spectrometer. Currently, the only application area considered for this instrument is solar applications. In this article, we present the optical system of the dual-gratings imaging spectrometer, illustrate several advantages of the new structure, and discuss new problems caused by the dual-gratings, which are referred to as overlap between two spectra and double image offset. We deduced the calculation process of the dual grating rotation angle, the relationship between the final acquired image and the slit, the relationship between the angle change between the dual gratings and the double image offset, and the relationship between the MTF upper limit reduction and the spatial frequency. This article also summarizes the shortcomings of this structure and studies the applicable fields under these shortcomings. At last, we simulate a dual-gratings imaging spectrometer system, compare this scheme with two traditional schemes, and conclude that this instrument has certain practical significance.

Hacia una traducción de “The Double Image” de Anne Sexton: apuntes sobre la bidireccionalidad de la maternidad

Anne Sexton (Boston, 1928-1974) es conocida por el público debido a su historial clínico y a su personalidad desgarradora en los escenarios que recitaba. Sin embargo, en este estudio nos centramos exclusivamente a las cuestiones relacionadas con la maternidad en “The Double Image” (To Bedlam and Part Way Back, 1963). La extensión del poema y su importancia en relación con el completo de su obra justifican el corpus reducido con el que pretendemos acercar dichas cuestiones. Un proceso documental de la traducción, entendida como proceso y producto, que premia el trasvase no solo del estilo y los hechos biográficos presentes en el texto, sino del contenido metafórico con una tendencia premeditada hacia la aceptabilidad, posible gracias a la transcreación (Etkind, 1982) del original en la cultura receptora.

Thermal Face Verification through Identification

This paper reports on a new approach to face verification in long-wavelength infrared radiation. Two face images were combined into one double image, which was then used as an input for a classification based on neural networks. For testing, we exploited two external and one homemade thermal face databases acquired in various variants. The method is reported to achieve a true acceptance rate of about 83%. We proved that the proposed method outperforms other studied baseline methods by about 20 percentage points. We also analyzed the issue of extending the performance of algorithms. We believe that the proposed double image method can also be applied to other spectral ranges and modalities different than the face.

Double-Image Visually Meaningful Encryption Algorithm Based on Compressed Sensing and Frft Embedding

The transmission of images via the Internet has grown exponentially in the past few decades. However, the Internet considered as an insecure method of information transmission may cause serious privacy issues. In order to overcome such potential security issues, a novel double-image visually meaningful encryption (DIVME) algorithm conjugating quantum cellular neural network (QCNN), compressed sensing (CS) and fractional Fourier transform (FRFT) is proposed in this paper. First, the wavelet coefficients of the two plain images are scrambled by the Fisher-Yates confusion algorithm, and then compressed by the key-controlled partial Hadamard matrix. The final meaningful cipher image is generated by embedding the encrypted images into a host image with the same resolution of the plain image via the FRFT-based embedding method. Besides, the eigenvalues of the plain images are utilized to generate the key stream to improve the ability of proposed DIVME algorithm to withstand the plaintext attacks. Afterwards, the plaintext eigenvalues are embedded into the alpha channel of the meaningful cipher image under control of the keys to reduce unnecessary storage space and transmission costs. Ultimately, the simulation results and security analyses indicate that the proposed DIVME algorithm is effective and can withstand multiple attacks.