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A panoramic view of the Li/CFx battery, ranging from mechanism to materials synthesis, the structure–performance relationships and energy-guided strategy are included.

A time-resolved electron paramagnetic resonance (TREPR) method with 40 ns time resolution and a high sensitivity suitable for the detection of short-lived radicals under thermal equilibrium is developed. The key is the introduction of a new detection technique named ultrawide single sideband phase sensitive detection (UWSSB-PSD) to the conventional continuous wave EPR, which remarkably enhanced the sensitivity for the detection of broadband transient signals compared with the direct detection protocol. By repeatedly triggering a transient kinetic event f(t) (e.g., by laser flash photolysis) under a 100 kHz magnetic field modulation with precise phase control, this technique can build an ultrawide single sideband modulated signal. After single sideband demodulation, the flicker noise-suppressed signal f(t) with an ultrawide bandwidth is recovered. An UWSSB-PSD TREPR spectrometer prototype has been built in our laboratory, which integrated timing sequence control, laser flash excitation, and data acquisition systems as well as the UWSSB-PSD algorithm with a conventional CW-EPR. It exhibited excellent performance in monitoring a model transient radical system, laser flash photolysis of benzophenone in isopropanol. Both the intense chemically induced dynamic electron polarization (CIDEP) signals and the much weaker thermal equilibrium EPR signals of the generated acetone ketyl radical and benzophenone ketyl radical were clearly observed within a wide timescale (ranging from sub-microsecond to milliseconds). This prototype validated the feasibility of the UWSSB-PSD technique and demonstrated its superior performance in studying complex photochemical systems containing various transient radicals, which complements the established TREPR techniques and provides a powerful tool for deep mechanistic understandings, such as in photoredox catalysis and artificial photosynthesis.

The influence of anti-braking system on the shimmy region and oscillation characteristics of the nose landing gear is studied. The moment generated by the braking system is modeled as a function of the adhesion coefficient and the torsional oscillation speed, and it is incorporated into the landing gear oscillation non-linear dynamic model. The results of analysis show that the braking frequency is increased by 50%, the area of the lateral dominant shimmy region is increased by 6.9%, the area of the torsional dominant shimmy region is reduced by 18.8%, and the amplitude of the torsional oscillation is suppressed. The braking amplitude is increased by 22%, the area of lateral dominant shimmy region is decreased by 3.1%, and the area of torsional dominant shimmy region is increased by 15.5%.

Like other countries, China has suffered severe consequences as a result of the COVID-19 outbreak and pandemic. The lockdown, physical distancing, social isolation has disrupted the day-to-day activities of its citizens. The higher education sector has had to adopt state-of-the-art technologies and use online platforms to hold classes in order to engage students and ensure the continuity of education for an effective learning process. The second wave and Delta variant of the virus compelled numerous Higher Educational Institutes (HEIs) to start offline and remote work for both academic and non-academic staff; a stressful ordeal for them. Teaching has always been a stressful career path, and the stress faced by teachers has adverse consequences on the learning and performance of students. In this paper, we aim to identify and study the stress HEIs staff perceive and its impact on their physical stress and wellbeing. The resilient coping mechanism was evaluated as a moderator in the relationship between the staff and faculty’s perceived and physical stress. Using a standard survey questionnaire, 500 responses were collected. The findings revealed that the staff with the highest perceived stress also showed high symptoms of physical stress. It also indicated that resilience copers experienced reduced or very inconsequential symptoms of physical stress regardless of high perceived stress, thus validating the important moderating function of resilience in the relationship between the physical and perceived stress of the employees.

The classic duodenal switch (DS) represents a minority of bariatric procedures due to its high complexity and potential for complications. A retrospective chart review was conducted on 100 laparoscopic DS cases from 2014 to 2018 at an accredited program in a rural community hospital and compared to 100 laparoscopic Roux-en-Y gastric bypasses (RYGB). Primary outcomes were 30-day morbidity and mortality. Secondary outcomes included anastomotic leak and remission of type 2 diabetes. There were more demographic risk factors for DS. The 30-day morbidity was higher for DS compared to RYGB (31% vs 13%, respectively; p = 0.0037). There was one mortality for DS and none for RYGB. There were statistically significant longer intraoperative times, greater EBL, and greater decrease in BMI for DS. The DS had a lower incidence of anastomotic ulcers (4% vs 13%, respectively; p = 0.0289), with a higher incidence of subsequent surgery beyond 30 days (21% vs 8%, respectively; p = 0.0160). There were 3 anastomotic leaks for DS and none for RYGB, although not statistically significant (p = 0.2463). The DS was more likely to eradicate hypertension, but the RYGB was more likely to eradicate GERD. There were no statistically significant differences for type 2 diabetes remission (92.1% vs 89.5%, respectively; p = 0.7239). Laparoscopic DS offers greater weight loss and hypertension remission, with lower incidence of anastomotic ulcers, but at the expense of greater morbidity and need for subsequent surgery, with no significant differences in type 2 diabetes remission when compared to RYGB in a rural community hospital program.

This study used a vacuum diffusion welding process to weld magnesium (Mg1) and aluminum (Al1060). The diffusion layers, with different phase compositions, were separated and extracted by grinding. The diffusion layers’ microstructures and phase compositions were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Furthermore, the corrosion resistance of each diffusion layer and the substrates were investigated and compared by performing corrosion immersion tests and linear polarization measurements in a 3.5 wt.% NaCl solution. The results showed that diffusion layers consisting of Mg2Al3, Mg17Al12, and Mg17Al12/Mg-based solid solutions were formed at the interface of the Mg1/Al1060 vacuum diffusion joint. Furthermore, each diffusion layer’s structure and morphology were of good quality, and the surfaces were free from defects. This result was obtained for a welding temperature of 440 °C and a holding time of 180 min. The corrosion current density of Mg1 was 2.199 × 10−3 A/cm2, while that of the Al1060, Mg2Al3, Mg17Al12, and Mg17Al12/Mg-based solid solutions increased by order of magnitude, reaching 1.483 × 10−4 A/cm2, 1.419 × 10−4 A/cm2, 1.346 × 10−4 A/cm2, and 3.320 × 10−4 A/cm2, respectively. The order of corrosion rate was Mg1 > Mg17Al12 and Mg-based solid solution > Mg2Al3 > Mg17Al12 > Al1060. Moreover, all diffusion layers exhibited an improved corrosion resistance compared to Mg1. This was especially the situation for the Mg2Al3 layer and Mg17Al12 layer, whose corrosion resistances were comparable to that of Al1060.

Two-dimensional transition metal carbides (MXenes) have a unique structure, excellent electronic conductivity and a low Li+ diffusion barrier, and show potential for application in energy storage. Especially, MXenes can act as a conductive matrix to achieve excellent lithium storage performance. Herein, a Ti3C2Tx MXene/carbon nanotubes@red phosphorus (Ti3C2Tx/CNTs@P) nanohybrid with stable Ti–O–P bonds is fabricated. The CNTs are introduced into Ti3C2Tx to construct a conductive network, and then the Ti3C2Tx/CNTs are combined with P by a ball-milling method. In this process, the surface oxygen-containing functional groups of Ti3C2Tx interact with P, forming Ti–O–P bonds. Owing to the large capacity contribution of P, the conductive network and buffering role of Ti3C2Tx/CNTs, and the effect of the Ti–O–P bond, the Ti3C2Tx/CNTs@P nanohybrid exhibits a superior reversible capacity of 2598 mA h g−1 at 0.05C (1C = 2600 mA g−1, based on the active material P), excellent cycling stability (2078 mA h g−1 after 500 cycles) and superior rate capability (454 mA h g−1 at 30C). These results demonstrate that the Ti3C2Tx/CNTs@P nanohybrid offers fascinating potential for high-performance lithium-ion batteries.

Red phosphorus is considered as a potentially promising anode material for lithium-ion batteries owing to its high theoretical specific capacity of 2596 mA h g−1 but facing the drawbacks of low conductivity and large volume change upon cycling. Herein, using fluffy carbon prepared from expanded rice, carbon-coated red phosphorus composites with a stable structure were synthesized via a simple route of ball milling the mixture of red phosphorus and fluffy carbon. The fluffy carbon was uniformly coated around the red phosphorus particles under shear force during the ball milling, and the formation of P–O–C bonds enhanced the contact between the red phosphorus and carbon. As a result, the fluffy-hard-carbon-coated red phosphorus with a high phosphorus loading of 80% exhibited superior electrochemical performance, i.e., a discharge capacity of 1655.9 mA h g−1 (based on the composite) at 0.05C and excellent cycle stability and rate capability (∼1230 mA h g−1 at 1C with 1000 cycles sustained at a capacity retention of 96%). This work not only demonstrates the superior design of the carbon-coated structure for a stable red phosphorus anode of lithium-ion batteries but also provides a simple, efficient, and easy-to-scale method to coat carbon onto the active materials.

In this paper, we propose a method for detecting handwritten ancient texts. The challenges in detecting this type of data are: the complexity of the layout of handwritten ancient texts, the varying text sizes, mixed arrangement of pictures and texts, the high number of hand-drawn patterns and the high background noise. Unlike general scene text detection tasks (ICDAR, TotalText, etc.), the texts in the images of ancient books are more densely distributed. For the features of the dataset, we propose a detection model based on cascade feature fusion called DFCOS, which aims to improve the fusion of localization information in lower layers. Specifically, bottom-up paths are created to use more localization signals from low-levels, and we incorporate skip connections to better extract information in the backbone, and then improve our model by parallel cascading. We verified the effectiveness of our DFCOS on HWAD (Handwritten Ancient-Books Dataset), a dataset containing four languages - Yi, Chinese, Tibetan and Tangut - provided by the Institute of Yi of Guizhou University of Engineering Science and National Digital Library of China, and its precision, recall and F-measure outperformed most of the existing text detection models.

In this study, pressure supplying device based on thermal expansion and vacuum diffusion bonding method were used to weld magnesium alloy (AZ91) and aluminum alloy (6061). To enhance the microstructure and bonding properties of the welded Mg/Al alloys, the annealing process was continuously implemented on the composite specimens. Elemental analysis and structural observation/compound identification were conducted using an electron probe microanalyzer and a scanning electron microscope, respectively. For further assessment of the diffusion zone, microstructural examination was carried out using a transmission electron microscope. Furthermore, tensile strength and hardness values were also measured. The results showed that the diffusion zone widens with increasing annealing temperatures, but it changed obviously when the annealing temperature was 300°C. Intermetallic compounds in the diffusion zone were identified as Al2Mg and Al12Mg17, the microstructure and elemental composition were uniformly distributed, and tensile strength was the largest for the specimen annealed at 250°C. A possible reason for this could be that 250°C is nearly similar to the recrystallization temperature of Mg/Al alloys. Therefore, 250°C was determined to be the most suitable annealing temperature. In addition, the thermal expansion pressure supplying process was appropriate for the diffusion bonding of Mg/Al alloys.

—In recent years, as the research of hidden chaotic systems has become a hot spot, the research of memristor theory has also made some progress. In this paper, a novel memristive hidden chaotic system is proposed by using the non-linear characteristics of the memristor and introducing it into the Sprott-2 system. Numerical simulations of the phase diagram, Lyapunov exponential spectrum, time-domain diagram, power spectrum density diagram, Poincare map, and 0-1 test diagram have proved the existence of system chaos. At the same time, the derivation process from the system state equation to the system circuit equation is given. According to the circuit theory, the memristor unit circuit and the improved memristor hidden chaotic system circuit are designed respectively. Finally, the circuit is verified by simulation. The simulation results are highly consistent with the numerical simulation results, which proves the system's physical feasibility and lays the foundation for its application in engineering technology.

The integrated transmission system of military armored vehicle is a kind of complex transmission system, which includes power transfer, power shifting, steering and manipulation. The transmission system is the key component for realizing the overall system functions of military armored vehicle. The rationality of structure design and feasibility of assembly are the precondition for implementation of function of transmission system, which are inseparable with the step of assembly design. In order to provide a prediction for the two designs in design stage of integrated transmission system, a pragmatic system to support virtual assembly for military armored vehicle integrated transmission system is established in this paper. In the virtual assembly system, the reconstruction method of assembly features of transmission system is investigated to implement the models transform from CAD system to virtual assembly. The planning method of virtual assembly sequence is proposed, which is based on the combination of cut set method of graph theory with interactive planning in virtual environment. The sequence planning method applied the pre-identified strategy for the subassembly to improve combination explosion problem of cut set method and reduce the blindness and uncertainty caused by the direct using of interactive planning. The mixed collision checking method based on the geometrical features is presented, which can meet the real-time performance and accuracy of virtual assembly. The parts accurate positioning method based on the reconstruction of assembly features elements is proposed, which can be used for the accurate positioning in virtual environment. With these technologies and methods, the system has been successfully applied to the virtual assembly for a certain type of integrated transmission system of military armored vehicle.

Phase-diversity (PD) is the least square adaptive-filter of the imaging system based on wave optics theory. It can use unknown extended object as the observation object to collect two or more images whose wave-front diversities are known and fixed. According to the images, the wave-front of the optical system can be calculated by PD, and simultaneously the estimation of ideal image for the observation object can be obtained. Phase-diverse speckle (PDS) technique extends PD by using a series of short-expose frames as the input. In this paper, we designed PDS experiment on a 1.23 m telescope and successfully got clear restored images of space objects. Under the observation condition that the atmospheric coherent length was not more than 8 cm at 500 nm wavelength in Changchun city, we replaced the deformable mirror with a plane mirror in adaptive optical system and separately used the moon and Polaris as the observation objects. For Polaris, the FWHW reduced from 20.6 to 5.3 (in pixel), which decreased about 74%. The experimental results demonstrate that PDS algorithm can be used on one meter-scale telescope in practical observation.

In computer animation applications, simplifying the mesh is an important technique to reduce the workload of visualization processing. In this paper, we propose a new method to simplify the dynamic model using local area and deformation information control. Our method uses an improved quadratic error metric with the local distortion measurement as the basic level. In addition, the deformation parameters are defined to be embedded in the summarized quadratic error, so that the regions with large deformations during the animation can be successfully retained. The new method is efficient and easy to implement, and in average can generate high-quality animated models with well-preserved local and deformation features on eacn frame.

Phase diversity speckle (PDS) is an image restoration technique which is based on the idea of phase diversity (PD). It uses multi-frame short-exposure image sequence to calculate their corresponding wave-front information. Each image pair consists of two images collected by two cameras at the same time with one in focus and the other with known defocus value. Multi-frame processing can significantly improve the target signal to noise ratio, and decrease noise influence. In this paper, based on the principle of pupil Fourier imaging, by adjusting the pupil size, we get different scales of the optical point spread function (PSF). Also, we analysis different camera noise distribution channels, location differences and other factors to optimize the objective evaluation function, and this can reduce the computational complexity and improve the processing speed of image restoration. In the indoor environment, we build optical platform, and use multi-frame phase diversity speckle to make experiment under different turbulence conditions. The experimental results show that the image restoration effect of the proposed method is close to the diffraction limit. Crown Copyright (C) 2013 Published by Elsevier GmbH. All rights reserved.

In order to improve the cell sensitivity or to satisfy the needs of a large field of view, a large size CCD pixel is usually chosen as detection unit in optical imaging systems. However, this methodology cannot meet the Nyquist sampling theorem, and thus generate ill-sampling images. In other words, the geometric resolution of images in optical diffraction limited systems is directly restricted by the size of CCD pixel. In this paper, a carefully designed optical mask is implemented to ensure loseless images before CCD sampling. By applying spatial spectral filtering technology, we can acquire images with appropriate resolution. The method presented in this paper significantly abates the resolution decline due to ill-sampling. By mathematical deduction and simulation, the geometric super resolution images can be achieved.

In the actual optical imaging system, in order to increase cell sensitivity or meet the needs of a large field of view, a large size CCD pixel is usually chosen as detection unit. This can not meet the Nyquist sampling theorem, and it belongs to ill-sampling. The geometric resolution of optical diffraction limited system image is directly restricted by the size of CCD pixel. In this paper, a reasonable optical mask is chosen, and this ensures the access to the CCD image information before sampling is lossless. Space spectral filtering technology is used, and appropriate resolution of the image is acquired. The method improves the resolution decline due to ill-sampling. By mathematical and simulation analysis, the effect of geometric super resolution image can be achieved.

The means to get the accurate high-orbit satellite magnitude can be significant in space target surveillance. This paper proposes a satellite photometric measurement method based on image processing. We calcu late the satellite magnitude by comparing the output value of camera’s CCD between the known fixed star and the satellite. We calculate the luminance value of a certain object on the acquired image using a background-removing method. According to the observation parameters such as azimuth, elevation, height and th e situation of the telescope, we can draw the star map on the image, so we can get the real magnitude of a certain fixe d star in the image. We derive a new method to calculate the magnitude value of a certain satellite according to the magnitude of the fixed star in the image. To guarantee the algorithm’s stability, we evaluate the measurement precision of the method, and analysis the restrict condition in actual application. We have made plenty of experiment of our system using large telescope in satellite surveillance, and testify the correctness of the algorithm. The experimental result shows that the precision of the proposed algorithm in satellite magnitude measurement is 0.24mv, and this method can be generalized to other relative fields. Keywords: Magnitude measurement, Satellite magnitude, Precision analysis, Image processing, High-orbit satellites

In computer graphics, animated models are widely used to represent time-varying data. And the progressive representation of such models can accelerate the speed of processing, transmission and storage. In this paper, we propose an efficient method to generate progressive animation models. Our method uses an improved curvature sensitive quadric error metric (QEM) criterion as basic measurement, which can preserve more local features on the surface. We append a deformation weight to the aggregated edge contraction cost during the whole animation to preserve more motion features. At last, we introduce a mesh optimization method for the animation sequence, which can efficiently improve the temporal coherence and reduce visual artifacts between adjacent frames. The results show our approach is efficient, easy to implement, and good quality progressive animation models can be generated at any level of detail.

In this paper, we propose an efficient method to generate optimal multiresolution models for deforming mesh sequence. By this method we define the importance degree of a triangle to be embedded into the quadric error metric (QEM) as a weight parameter, so that the new metric cannot only measure distance error but also reflect geometric variation of local areas. We append a deformation degree weight to the aggregated edge contraction cost for the whole animation. This new metric can preserve not only the model's individual geometric features, but also the features only appeared during the deforming animation. In addition, a mesh optimization method has also been proposed to allow visual distortion of the simplified models to be further alleviated. Our approach is efficient in operation, easy for implementation, and as a result a good quality of dynamic approximations with well-preserved fine details can be generated at any given frame on average.

The method to get high-orbit satellite basic information such as geometry and material characteristic, is an important goal in the field of space posture apperception. In this paper, we calculate the satellite magnitude by comparing the output value of camera’s CCD between the known fixed star and the satellite. We select certain reference stars to calculate the luminance value of a certain object on the acquired image using a background-removing method. We make time-domain analysis of the measurement data, and get the statistic result. With the knowledge of the theory brightness of the target, we estimate the geometric characteristics of the target. We have got a serious of the images of a certain satellite on large telescope. The experimental results demonstrate that, the accuracy of the measured magnitude is better than 0.12Mv, and the estimation error of the target reflection surface size is less than 15%.

Phase diversity speckle (PDS) is an image restoration technique which is based on the idea of phase diversity (PD). It uses multi-frame short-exposure image sequence to calculate their corresponding wave-front information. Each image pair consists of two images collected by two cameras at the same time with one in focus and the other with known defocus value. Multi-frame processing can significantly improve the target signal to noise ratio (SNR), and decrease noise influence. In this paper, based on the principle of pupil Fourier imaging, by adjusting the pupil size, we get different scales of the optical point spread function (PSF). Also, we analysis different camera noise distribution channels, location differences and other factors to improve the processing speed of image restoration. In the indoor environment, we build optical platform, and use multi-frame phase diversity speckle to make experiment under different turbulence conditions. The experimental results show that with the camera size of 128128 pixels, the image restoration effect is close to the diffraction limit. 2013 SPIE.

In this paper, we develop a lucky imaging system to restore astronomical images through atmosphere turbulence. Our system takes very short exposures, on the order of the atmospheric coherence time. The rapidly changing turbulence leads to a very variable point spread function (PSF), and the variability of the PSF leads to some frames having better quality than the rest. Only the best frames are selected, aligned and co-added to give a final image with much improved angular resolution. Our system mainly consists of five parts: preprocessing, frame selection, image registration, image reconstruction, and image enhancement. Our lucky imaging system has been successfully applied to restore the astronomical images taken by a 1.23m telescope. We have got clear images of moon surface and Jupiter, and our system can be demonstrated to greatly improve the imaging resolution through atmospheric turbulence.

In computer graphics, investigation has been made in many years in LOD (Level of Detail) models generation to alleviate the workload of visualization processing. However, most of the existing algorithms only focus on static models , and very little works are to deal with animation models. In this paper, we propose a feature aware method for generating multiresolution animation models. By the method we first use a normal deviation based quadric error metric to generate a base hierarchy , and then update the edge contraction order progressively from the first frame to the last one . Thus, we can get the simplified versions for each frame in the animation sequence . Finally , a mesh optimization method is proposed to allow visual distortion of the simplified models to be further alleviated. We demonstrate that our method works efficiently and can generate better approximations with well-preserved features for each frame than previous methods.

In this paper, we propose a new method to approximate deforming models based on torsion detection. We propose the use of surface torsion to represent local features on the original model, and consider it as an additional weight factor when calculating the edge contraction cost during the simplification process. The approximations of the original deforming models are generated progressively from the first frame to the last one. Based on the edge contraction sequence in the previous frame, the contraction order in the current frame is adjusted according to the deformation degree. Our approach is fast, easy to implement, and as a result good quality approximations with well-preserved fine details can be generated at any given frame.

An algorithm for estimating displacement of the moving target and background by shift theory of Fourier transform is presented. According to the relation between the change and the Fourier transform of image sequence, the method employs the displacement value of the moving target and background by the difference of Fourier phase spectrum. The algorithm estimates the movements from the whole field of the image with excellent global property. This paper provides the calculus and experiments of the algorithm which show the accuracy of 1 pixel.

In computer graphics applications, mesh coarsening is an important technique to alleviate the workload of visualization processing. Compared to the extensive works on static model approximation, very little attentions have been paid to animated models. In this paper, we propose a new method to approximate animated models with local area distortion and deformation degree control. Our method uses an improved quadric error metric guided by a local area distortion measurement as a basic hierarchy. Also, we define a deformation degree parameter to be embedded into the aggregated quadric errors, so areas with large deformation during the animation can be successfully preserved. Finally, a mesh optimization process is proposed to further reduce the geometric distortion for each frame. Our approach is fast, easy to implement, and as a result good quality dynamic approximations with well-preserved sharp features can be generated at any given frame.

In computer graphics, investigation has been made in many years in progressive models generation to alleviate the workload of visualization processing. However, most of the existing algorithms only focus on static meshes, and very little works are to deal with animation models. In this paper, we propose an improved method for generating progressive multiresolution animation models. By the method we first use a normal deviation parameter to improve the famous QEM method as our basic edge contraction metric to generate a base hierarchy. The sequence of the simplified models is generated progressively from the first frame to the last one. Based on the edge contraction sequence in the previous frame, the contraction order in the current frame is adjusted according to the deformation degree. We demonstrate that our method works efficiently and can generate better approximations with well-preserved features than previous methods.

Although animated meshes are frequently used in numerous domains, only few works have been proposed until now for simplifying such data. In this paper, we propose a new method for generating progressive animated models based on local feature analysis and deformation area preservation. We propose the use of solid angle and height value for a non-hyperbolic vertex to define the local feature parameter. This local factor is embedded to the vertex quadric error matrix when calculating the edge collapse cost. In order to preserve the areas with large deformation, we add deformation degree weight to the aggregated quadric errors when computing the unified edge contraction sequence. Finally, a mesh optimization process is proposed to further reduce the geometric distortion for each frame. Our approach is fast, easy to implement, and as a result good quality dynamic approximations with well-preserved fine details can be generated at any given frame.

In this paper, we propose an efficient method to generate optimal multiresolution dynamic models. By the method, we define the triangle importance degree as a weight parameter to be embedded to the edge contraction cost, so the new metric can not only measure distance error but also reflect geometric variation of local areas. A deformation degree weight is appended to the aggregated edge contraction cost for the whole animation, thus sharp features on areas with large deformation can be preserved. In addition, a process of mesh optimization and validity check can further alleviate the geometric distortion of the approximations. Our approach is efficient in operation, easy for implementation, and as a result high quality of dynamic approximations with well-preserved fine details can be generated at any given frame.

In computer graphics, animated models have been widely used to represent time-varying data. Reducing the models complexly is a common way to overcome the rendering limitations. In this paper, we propose an efficient method for generating multiresolution animated models based on deformation distance analysis. Our method obtains different LOD models by performing iterative edge contraction operations. We use deformation distance to analysis the deformation degree of the triangle planes during the whole animation, and define a deformation weight to be added to the aggregated edge contraction cost. Thus features in areas with large deformation can be preserved well. Besides, we propose a mesh optimization method for dynamic model sequence, which can efficiently improve the temporal coherence and reduce visual artifacts between adjacent frames. The results show our approach is efficient, easy to implement, and good quality animated approximations with well-preserved fine details can be generated at any given frame.

In computer graphics, investigation has been made in many years in mesh simplification to alleviate the workload of visualization processing. However, most of the simplification algorithms proposed focus on static meshes, and very little works are to deal with deforming surfaces. In this paper, we propose a novel method for generating progressive multiresolution models of deforming surfaces base on shape feature analysis. By the method we first use the curvature and torsion to analysis the shape feature of the original model, then use the famous QEM method as our basic edge contraction metric to generate a base hierarchy. The sequence of the simplified models is generated progressively from frame to frame. Based on the edge collapse sequence in the previous frame, edge contraction order is adjusted according to the deformation degree in the current frame. We demonstrate that our method works efficiently and can generate better approximations with well-preserved features than previous methods.

The resolution of astronomical imaging from large optical telescopes is usually limited by the blurring effects of refractive index fluctuations in the Earth’s atmosphere. In this letter, we develop a lucky imaging system to restore astronomical images through atmosphere turbulence on large telescope. Our system takes very short exposures, on the order of the atmospheric coherence time. The rapidly changing turbulence leads to a very variable point spread function (PSF), and the variability of the PSF leads to some frames having better quality than the rest. Only the best frames are selected, aligned and co-added to give a final image with much improved angular resolution. Our lucky imaging system is successfully applied to restore the astronomical images taken by a 1.23 m telescope. We get clear images of moon surface, Jupiter, and Saturn, and our system can be demonstrated to greatly improve the imaging resolution through atmospheric turbulence. OCIS codes: 100.3020, 010.1290, 010.7060. doi: 10.3788/COL201210.S21004. The resolution of all large ground-based telescopes is severely limited by the effects of atmospheric turbulence. At even the best sites, the resolution of large telescope is degraded by at least a factor of five in the visible. The recovery of the full theoretical resolution of large telescopes in the presence of atmospheric turbulence has been a major goal of technological developments in the field of as