Low-Energy Pulsed Ion Beam Technology with Ultra-High Material Removal Resolution and Widely Adjustable Removal Efficiency

High-precision optical component manufacturing by ion beam machining tools with ultra-high material removal resolution and dynamically adjustable removal efficiency is important in various industries. In this paper, we propose a low-energy pulsed ion beam (LPIB) technology that can obtain a single pulse with high-resolution material removal by adjusting the pulse frequency and duty cycle, and enable the dynamic adjustment of the removal efficiency. The pulse frequency is 1–100 Hz, and the duty cycle is 0–100%. For monocrystalline silicon, the pulse frequency and duty cycle are set to 100 Hz and 1%, respectively; thus, the single-shot pulse depth removal resolution of material is 6.7 × 10−4 nm, which means every 21 pulses can remove one silicon atom layer. Compared with IBF, where the removal resolution of the maximum depth is about 0.01 nm, the controllable resolution is one to two orders of magnitude higher. There is a linear relationship between the removal efficiency of the pulsed ion beam removal function and the pulse duty ratio. The material removal of a single pulse can be adjusted in real time by adjusting the pulse duty cycle and frequency. Owing to its high resolution and wide adjustable removal efficiency, LPIB has broad application prospects in the field of sub-nano-precision surface modification, quality tuning of inertial resonant devices, and so on. This technology is expected to advance surface processing and ultra-precision manufacturing

Panchromatic and Multispectral Image Fusion Combining GIHS, NSST, and PCA

Spatial and spectral information are essential sources of information in remote sensing applications, and the fusion of panchromatic and multispectral images effectively combines the advantages of both. Due to the existence of two main classes of fusion methods—component substitution (CS) and multi-resolution analysis (MRA), which have different advantages—mixed approaches are possible. This paper proposes a fusion algorithm that combines the advantages of generalized intensity–hue–saturation (GIHS) and non-subsampled shearlet transform (NSST) with principal component analysis (PCA) technology to extract more spatial information. Therefore, compared with the traditional algorithms, the algorithm in this paper uses PCA transformation to obtain spatial structure components from PAN and MS, which can effectively inject spatial information while maintaining spectral information with high fidelity. First, PCA is applied to each band of low-resolution multispectral (MS) images and panchromatic (PAN) images to obtain the first principal component and to calculate the intensity of MS. Then, the PAN image is fused with the first principal component using NSST, and the fused image is used to replace the original intensity component. Finally, a fused image is obtained using the GIHS algorithm. Using the urban, plants and water, farmland, and desert images from GeoEye-1, WorldView-4, GaoFen-7 (GF-7), and Gaofen Multi-Mode (GFDM) as experimental data, this fusion method was tested using the evaluation mode with references and the evaluation mode without references and was compared with five other classic fusion algorithms. The results showed that the algorithms in this paper had better fusion performances in both spectral preservation and spatial information incorporation

Distribution Pattern of Landslides Triggered by the 2014 Ludian Earthquake of China: Implications for Regional Threshold Topography and the Seismogenic Fault Identification

The 3 August 2014 Ludian earthquake with a moment magnitude scale (Mw) of 6.1 induced widespread landslides in the Ludian County and its vicinity. This paper presents a preliminary analysis of the distribution patterns and characteristics of these co-seismic landslides. In total, 1826 landslides with a total area of 19.12 km2 triggered by the 3 August 2014 Ludian earthquake were visually interpreted using high-resolution aerial photos and Landsat-8 images. The sizes of the landslides were, in general, much smaller than those triggered by the 2008 Wenchuan earthquake. The main types of landslides were rock falls and shallow, disrupted landslides from steep slopes. These landslides were unevenly distributed within the study area and concentrated within an elliptical area with a 25-km NW–SE striking long axis and a 15-km NW–SE striking short axis. Three indexes including landslides number (LN), landslide area ratio (LAR), and landslide density (LD) were employed to analyze the relation between the landslide distribution and several factors, including lithology, elevation, slope, aspect, distance to epicenter and distance to the active fault. The results show that slopes consisting of deeply weathered and fractured sandstones and mudstones were the more susceptible to co-seismic landslides. The elevation range of high landslide susceptibility was between 900–1300 m and 1800–2000 m. There was a generally positive correlation between co-seismic landslides and slope angle, until a maximum for the slope class 40°–50°. The co-seismic landslides occurred preferably on Southeast (SE), South (S) and Southwest (SW) oriented slopes. Results also show that the landslide concentration tends to decrease with distance from the surface projection of the epicenter rather than the seismogenic fault, and the highest landslide concentration is located within a 5–6 km distance of the seismogenic fault. Regarding the epicenter, the largest landslide clusters were found on the SE, northeast by east (NEE) and nearly West (W) of the epicenter. In addition, we also suggest that statistical results of slope gradients of landslides might imply a threshold topography of the study area within a tectonically active background. By analogy with other events, the statistical results of landslides aspects also imply the seismogenic fault of the Ludian earthquake might have been the Northwest (NW)-trending fault, which is consistent with other studies

Descending thoracic aortic dissection after covered stent for adult aortic coarctation: Technical or physiopathologic?

Covered stent graft implantation is currently the most commonly used modality for the management of adult aortic coarctation. Although the risk of descending thoracic aortic dissection after covered stent graft implantation is low, sometimes it may cause serious medical consequences or even death. We report one adult aortic coarctation patient with early postoperative descending thoracic aortic dissection after covered stent graft implantation. The patient underwent second operation of thoracic endovascular aortic reconstruction and was discharged 6 days after the operation. This case is not rare, but we hope that the complete diagnosis and treatment process of this case and discussion pertaining to surgical treatment method and its complications could serve as a reference for clinicians in dealing with such situations

Microwave-assisted hydrothermal synthesis of a&b-oriented zeolite T membranes and their pervaporation properties

By microwave-assisted hydrothermal synthesis (MAHS) method, a&b-oriented zeolite T membranes were firstly prepared on the alpha-Al(2)O(3) tubes from the a&b-oriented seed layers. By adjusting the pH value of the seed suspension, zeolite T seeds about 8.5 mu m long were uniformly deposited on the support surface with their a&b-axes perpendicular to the support surface. After the secondary growth, the a&b-oriented seed layers grew into a&b-oriented zeolite T membranes with the thickness of about 7 mu m. A formation mechanism of the membranes was proposed, which could provide general guidance for the preparation of other types of zeolite membranes. The as-synthesized membranes displayed high pervaporation (PV) performance for alcohol/water liquid mixtures. Aiming at the application in the industrial dehydration process, the hydrothermal stability and acid stability of the zeolite T membranes were also investigated. (C) 2008 Elsevier B.V. All rights reserved

Scratch Morphology Transformation: An Alternative Method of Scratch Processing on Optical Surface

The scratches on an optical surface can worsen the performance of elements. The normal process method is removing scratches entirely. However, it is a tough and high-cost requirement of removing extremely deep scratches and maintaining all the other excellent indicators at the same time. As the alternative of removing, we propose the method of scratch morphology transformation to diminish the drawbacks induced by scratches. We measure the morphology of scratches, establish the transformation models and transform them to the needed shape. In engineering applications, transformation can solve scratch drawbacks or limitations in an efficient and effective way. Then, residual scratches become acceptable. The transformation can also be amalgamated into the error figuring processes. Typical scratch transforming examples are experimented and AFM measurement is conducted. We explore the rule of scratch morphology transformation by two typical fabrication means: magnetorheological finishing (MRF) and HF etching. This morphology transforming method is an economical alternative for current defect-free fabrication. That will significantly decrease fabrication time, cost and risk, while the optical quality maintain

Low-Energy Pulsed Ion Beam Technology with Ultra-High Material Removal Resolution and Widely Adjustable Removal Efficiency

High-precision optical component manufacturing by ion beam machining tools with ultra-high material removal resolution and dynamically adjustable removal efficiency is important in various industries. In this paper, we propose a low-energy pulsed ion beam (LPIB) technology that can obtain a single pulse with high-resolution material removal by adjusting the pulse frequency and duty cycle, and enable the dynamic adjustment of the removal efficiency. The pulse frequency is 1–100 Hz, and the duty cycle is 0–100%. For monocrystalline silicon, the pulse frequency and duty cycle are set to 100 Hz and 1%, respectively; thus, the single-shot pulse depth removal resolution of material is 6.7 × 10−4 nm, which means every 21 pulses can remove one silicon atom layer. Compared with IBF, where the removal resolution of the maximum depth is about 0.01 nm, the controllable resolution is one to two orders of magnitude higher. There is a linear relationship between the removal efficiency of the pulsed ion beam removal function and the pulse duty ratio. The material removal of a single pulse can be adjusted in real time by adjusting the pulse duty cycle and frequency. Owing to its high resolution and wide adjustable removal efficiency, LPIB has broad application prospects in the field of sub-nano-precision surface modification, quality tuning of inertial resonant devices, and so on. This technology is expected to advance surface processing and ultra-precision manufacturing