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The electronics production experiences a continuous trend towards miniaturization of components. Smaller components lead to a number of challenges in the Surface Mount Technology (SMT) process chain to ensure a stable production process. This paper provides an overview on the main SMT production processes and focuses on the stencil printing process, which is said to be an error-prone process and has the demand of further optimization and research. One important criteria for the solder paste printing stencils is the area ratio (AR), which is defined by the IPC-7525 as the area of the aperture opening to the area of the aperture walls. Especially in mixed assembly designs AR is becoming critical low for the miniaturized 01005 components. In this paper, the printing process for miniaturized components is investigated using specially designed area ratio test stencils and an active squeegee system. The design of these stencils includes values for the AR from 0.65 down to 0.45 with different aperture shapes, which include gradually adjusted in length and width, rectangles as well as circular apertures for reference. Furthermore, the orientation of the rectangular apertures in relation to the printing direction is regarded. To include the effect of the active squeegee system all tests were conducted with the system activated as well as deactivated.

In the Global Navigation Satellite System (GNSS), integer ambiguity resolution (IAR) is critical to highly precise, fast positioning and attitude determination. The combination of ambiguity resolution and validation is usually named as integer aperture (IA) ambiguity resolution, which provides the foundation for the ambiguity validation. Based on the IA ambiguity resolution theory, fixed failure-rate (FFR) approach is proposed to realize the controlling of failure rate. Though fixed failure-rate approach can be applied for many acceptance tests, it is time-consuming and cannot be precisely realized in instantaneous scenario. In order to overcome these problems, this contribution will introduce an instantaneous and controllable (iCON) IA ambiguity resolution approach based on difference test for the first time. It has the following advantages: (1) It can independently compute the critical value by the required failure rate and GNSS model Q without external information such as look-up table; (2) It is instantaneous, and the stronger GNSS model, the better performance IA estimator will behave; (3) It can balance the instantaneous and precise quality control by adjusting the number of pull-in regions. The simulation experiment based on single and multi-frequencies, multi-GNSS systems verify the advantages of this approach. It completely solves the time consumption in precise quality control and has the same performance as the FFR approach based on Monte Carlo integral. It is available for instantaneous and precise GNSS applications, such as carrier phase based positioning, PPP-RTK, attitude determination, and will be a better choice the multi-frequency, multi-GNSS ambiguity resolution.

The basic principle of microwave holographic metrology is simply described. The mathematic relationships between the phase error of aperture field and the optical path-length difference of antenna reflector, between normal error and surface accuracy were deduced. Take the gravity deformation of a large reflector antenna for deep space observation for example, the simulation method in the far-field used for microwave holographic metrology of surface accuracy of reflector antenna was presented. The holographic results of the pattern simulation with low-resolution medium accuracy and high-resolution high accuracy were simulated respectively. The simulation results show that reflector accuracy was increased from 1.77 to 0.241 mm and the antenna gain was increased by 1.75 dB at X band in the period of low-resolution medium accuracy; The gain at Ka band was increased by 0.95 dB and the side-lobe level was decreased by 0.8 dB in the period of low-resolution using high-frequency high-resolution simulation.

The tibial drill-guide angle in anterior cruciate ligament (ACL) reconstruction influences the tunnel placement and graft-tunnel force, and is potentially associated with post-operative tunnel widening. This study aimed to examine the effect of the drill-guide angle on the stress redistribution at the tibial tunnel aperture after anatomic single-bundle ACL reconstruction.A validated finite element model of human knee joint was used. The tibial tunnel with drill-guide angle ranging from 30° to 75° was investigated. The post-operative stress redistribution in tibia under the compressive, valgus, rotational and complex loadings was analysed.Compressive loading played a leading role on the stress redistribution at intra-articular tibial tunnel aperture. After ACL reconstruction, stress concentration occurred in the anterior and posterior regions of tunnel aperture while stress reduction occurred in the lateral and posteromedial regions under the compressive loading. Stress redistribution was partially alleviated by using the drill-guide angle ranging from 55° to 65°.The present study quantified the effect of bone tunnel drill-guide angle on the post-operative stress redistribution. This phenomenon potentially contributed to tunnel widening. A tunnel drill-guide angle ranging from 55° to 65° was proposed based on the biomechanical rationale. It could serve as a helpful surgical guide for ACL reconstruction.

This paper presents a fuzzy control system of the exposure value (EV) of a digital camera. The intelligent controller considers fuzzy input variables, applies fuzzy rules and provides fuzzy and crisp results for the focal length, EV, aperture, and speed of a digital camera in an automatic way. The control system calculates the most appropriate solution considering the distance to the subject and the lighting conditions. The results obtained resemble the behavior of an intermediate level photographer. The prototype controller was developed with Xfuzzy and Java.

Nowadays there are several approaches for optical form measurement of precision components. Optical single point sensors as well as optical matrix sensors are applied for this measurement task. Scanning a specimen with a point sensor requires long measuring times. Hence, drifts of the stages or variations of the air temperature can cause measurement errors. Using a matrix sensor yields to large amounts of data, needs high computing power and may lead to difficulties due to comparably low frame rates if the object under investigation is moving. Another approach for measuring highly curved surfaces are computer generated holograms (CGH) for a Fizeau null-test, but this is expensive and needs very accurate manufacturing of the CGH as well as a precise alignment to the object under test [1].

We propose a novel approach to tracking objects by low-level line correspondences. In our implementation we show that this approach is usable even when tracking objects with lack of texture, exploiting situations, when feature-based trackers fails due to the aperture problem. Furthermore, we suggest an approach to failure detection and recovery to maintain long-term stability. This is achieved by remembering configurations which lead to good pose estimations and using them later for tracking corrections. We carried out experiments on several sequences of different types. The proposed tracker proves itself as competitive or superior to state-of-the-art trackers in both standard and low-textured scenes. © 2013 Springer-Verlag.

Fracture networks often are hierarchical and always present some kinds of scaling invariance. To consider these special characteristics, a geomathematical method is proposed in this paper to simulate the fracture distribution. The method mainly consists of: simulation of location, direction, aperture, and fracture connectivity, just as the application in Gaosong Triassic dolomite. The fracture locations are simulated using SGS method; the fracture strikes are simulated using principle component analysis method and Ordinary Kriging method. From the result, simulated fracture distribution corresponds well to hydraulic conductivity map, real fracture zone, and spring water distribution.

Towed line array sonar has attracted attention for its property of low frequency and big aperture. As an important part of the wet-end, the towed array has developed rapidly. The liquid towed array is more mature for its being used earlier. Meanwhile, more studies on solid towed array have been taken for its special feature. To analyze the performances on the phase consistency of hydrophones and the beam forming performance of the solid towed array, the lake trail results are presented. The analysis results show that the solid towed array has good performance on phase consistency among different hydrophones and on beam forming. Especially under the condition of being towed, the solid towed array has better performance for it is less sensitive to the vibration noise.

A mathematical model that expresses the relationship between Near-infrared light intensity and automatic threshold for automatic kiwifruit surface defect detection was established. By applying different levels of Near-infrared light intensity to machine vision system, 268 images were collected. Then the images were processed with MATLAB using the method to detect kiwifruit defects based on Near-infrared light source .The obtained 268 sets of data on Automatic Threshold T 0 and Manual Threshold T 1were divided into 19 groups according to different aperture and light intensity. After processing data, a series of linear equations about the relationship between Near-infrared light intensity and Automatic Threshold T 0, with function fitting coefficient of R 2 > 95% was obtained. Finally, relationship between T 0 and T 1 was analyzed according to the effectiveness of image processing results and constant P was introduced to revise Automatic Threshold T 0.Thus, a mathematical model needed to gain kiwifruit defects detection threshold, namely Model Threshold T, was established.

Given two pictures of the same scene captured using the same camera and the same lens, the one captured with a large aperture will appear partially blurred while the other captured with a small aperture will appear totally sharp. This paper investigates two possible ways of inferring depth of the scene from such an image pair with the constraint that both pictures are focused on the closest point of the scene. Our first method uses a series of Gaussian kernels to blur the image pair, and in the second method, the image pair will be shrunk to a series of smaller dimensions. In both methods, sharp areas in both images will always stay similar to each other, whereas the areas that appear sharp in one image but blurred in the other will not be similar until they are blurred using a large Gaussian kernel or shrunk to small dimensions. This observation enables us to roughly tell which objects in the scene are closer to us and which ones are farther away. At the end of this paper, we will discuss the limitations of our proposed approaches and some of the directions for future work.

With the exceptions of Synchrotron Radiation sources, beams of accelerated particles are generally designed to interact either with one another (in the case of colliders) or with a specific target (for the operation of Fixed Target experiments, the production of secondary beams and for medical applications). However, in addition to the desired interactions there are unwanted interactions of the high energy particles which can produce undesirable side effects. These interactions can arise from the unavoidable presence of residual gas in the accelerator vacuum chamber, or from the impact of particles lost from the beam on aperture limits around the accelerator, as well as the final beam dump. The wanted collisions of the beams in a collider to produce potentially interesting High Energy Physics events also reduces the density of the circulating beam and can produce high fluxes of secondary particles.

Recently, jaw size was changed from 4 mm aper- ture (J4) to 1 mm (J1) in TomoTherapy Hi-Art II® (TomoThe- rapy Inc., Madison, WI) to improve the longitudinal (IEC-Y) resolution of megavoltage computed tomography (MVCT) images. This study attempted to conduct a comparative analy- sis on the effect of jaw aperture size of MVCT on image quali- ty and dose. Also, this study investigated the clinical effect of jaw aperture size on highly radiosensitive lens dose. MVCT image quality test (image noise, uniformity, contrast linearity, and spatial resolution) and multiple scan average dose (MSAD) were measured to examine the effect of change in jaw aperture size. A head phantom and photoluminescence glass dosimeters (PLDs) were used to measure exposed lens dose (cGy). For image quality, the change in jaw aperture size did not have a significant effect on image noise, uniformity, con- trast linearity, and spatial resolution although showing slight improvement of image quality. FHWM was 6.7 mm and 4.1 mm in J4 and J1, respectively, which represents enhancement in the longitudinal resolution of MVCT image. MSAD of cen- ter point was approximately 0.69-2.32 cGy (peripheral: 0.83- 2.48 cGy) in J4, and 0.85-2.81 cGy (peripheral: 1.05-2.86 cGy) in J1. The measured lens dose using PLDs ranged 0.92-3.36 cGy and 1.06-3.91 cGy in J4 and J1, respectively, indicating dose increase for the narrower jaw aperture size. An addition- al dose of 3.86 cGy, 1.92 cGy, and 1.22 cGy was delivered for a pitch of 1, 2, and 3, respectively during MVCT scan per frac- tion in head and neck treatment plans. Therefore, 15% in- crease in imaging dose with 1 mm aperture jaw should be allowed for compared to that with previous 4 mm aperture jaw.

A double-tapered type of fiber probe with a typical aperture diameter of 100 nm and the GeO2-doped silica core has been widely used for near-field optical microscopy in infrared and visible wavelength regions. However, it is difficult to employ such commercial probes for near-ultraviolet applications because the GeO2-doped silica fiber probe has the strong guiding loss based on the Rayleigh scattering. Furthermore, the GeO2-doped core, under the excitation of a visible light, generates photoluminescence and scattered lights which seriously decreases the ratio of near-field signal to background noise in some near-field applications such as fluorescence imaging and Raman scattering spectroscopy. This chapter describes various types of probe, fabrication methods, and imaging applications. 7.

Intensity Modulated Radiation Therapy (IMRT) is a means of delivering radiation therapy where the intensity of the beam is varied within the treatment field. One of the main problems of IMRT, which becomes even more apparent as the complexity of the IMRT plan increases, is the amazing increase in the number of Monitor Units (MU) required to deliver a fractionated treatment. The difficulty with this increase in MU is its association with increased treatment times and a greater leakage of radiation from the MLCs increasing the total body dose and the risk of secondary cancers in patients. Many approaches have been taken to reduce the complexity. In this study, we used a direct aperture optimization (DAO) IMRT plan Direct aperture optimization IMRT is an IMRT method in which the aperture shapes and aperture weights are optimized simultaneously, and the MLC constraints and the number of segments are directly included in the optimization process. In DAO-IMRT planning, the planner specifies the planning objectives on the basis of the dose volume criteria for the target and critical structures as well as the number of beam segments to be delivered. The optimization only considers aperture shapes that satisfy the conditions set by the MLC. As a result, high-quality DAO-IMRT treatment plans can be generated using fewer segments (apertures) per beam. We investigated the dosimetric and technical differences in using DAO-IMRT. We also compared DAO-IMRT plans with standard beamlet-IMRT plans on phantom in terms of dosimetry, number of segments, and monitor units. In this study, we found that DAO-IMRT can achieve equal or better plans than standard beamlet-IMRT in dose optimization, secondary scattering dose and treatment time. The DAO-IMRT planning is proficient, and the plans can be delivered efficiently because small numbers of segments and monitor units are used.

In order to solve the explosive simulation to realize real-time and realistic, this paper puts forward the real-time explosive simulation method based on the particle system. The basic idea is to use a variety of simple particle effects simulating the aperture of the explosion, splash, and fire. Then according to the characteristics of the explosive model, the simple particles are assembled in one particle system, unified timing to realize the highly realistic explosive special effects.

A Five Hundred meter Aperture Spherical radio Telescope (FAST) is being built in China, and a similarity model was set up in Beijing for further study of FAST. In FAST, A six-cable driven parallel manipulator is adopted as the first level adjustable feed support system. This paper addresses the complete modeling method of the six-cable driven parallel manipulator of FAST with cable mass and elastic deformation. Comparing with the precise catenary modeling equation, modeling and solution of line equation is easier and quicker, but has modeling error for cable driven parallel manipulator. Hence, analysis and compensation method of the modeling error is studied in detail, which encourages the line equation to model and solve the six-cable driven parallel manipulator accurately. Finally, simulation and experiment have been done for supporting the modeling and error compensation methods in this paper.

Volumetric Modulated Arc Therapy (VMAT) is a sophisticated radiotherapy treatment delivery modality in which a medical linear accelerator arcs around a patient, with concurrent dynamic variation of multi-leaf collimator aperture, dose rate, and gantry speed, to produce a radiation dose distribution which delivers a highly conformal dose to the target while minimizing the incidental irradiation of normal tissue. Treatment planning for VMAT is an inverse problem, requiring optimization of the linear accelerator parameters to produce the desired radiation dose distribution, which is specified by dose-volume objectives. In this study, the feasibility of an ant colony algorithm for VMAT treatment planning is demonstrated by the ability of the algorithm to produce a treatment plan, which satisfies given dose-volume objectives, for a phantom target/critical structure geometry. Three experiments were conducted: one in which the optimization included only heuristic information, one in which there was exclusively a pheromone trail update, and one where there was both a pheromone trail update and an applied heuristic. The results indicate that the use of both a pheromone trail update and heuristic information during the optimization yields solutions of the highest quality.

In this chapter, details of the DEMS instrument design and construction created as part of this thesis are presented. The instrument employs a dual thin-layer electrochemical flow cell and microporous PTFE membrane interfaced to a high vacuum system containing a QMS. The vacuum system design possesses a tubular aperture to control and direct the flux of gas through the cross-beam ion source, whilst a 3-stage differentially pumped vacuum construction provided optimum operating pressures of the QMS in order to maximise instrument sensitivity.

Based on the characteristic of the linear shaped charge and the theory of jet penetration target, a method, which adopts explicit dynamic analyzing program AUTODYN to simulate the process of the linear shaped charge jet penetration through the target, is proposed in this paper. The trend and rule of aperture size changing with time during the process of the jet penetration the target, are analyzed. The physics phenomena and rule are basically same between emulational result and testing result. It shows that analytical model and emulational method are reasonable and practical.

In this book, two flow configurations are investigated, namely axi-symmetric confined arrangements and two-dimensional planar jets. A fluid jet enters a cylindrical chamber through an aperture in an upper disk. An annular clearance between the cylinder lateral wall and the disc allows fluid to flow out of the enclosure.

It is of great significance to digitize ancient paintings and calligraphy. A typical way to acquire them is using a linear CCD based large area table scanner. But it is not suitable for scanning fresco. Our lab has recently developed a new equipment to solve it and hopefully it would shed new light on the documentation of ancient paintings. This paper will discuss the way to improve image sharpness both from theory and practice perspective. In theory, the theoretical optimal aperture determination is discussed. In practice, a test chart is proposed to test the gradual image quality deterioration. From the photo of test chart, the clear part is determined and the percentage of clear part is used to determine the practical optimal aperture. A workflow integrating the above techniques is also proposed. The simulated acquiring experiment shows the method and the scanning hardware can achieve satisfactory results.

We propose modifying the aperture of a conventional color camera so that the effective aperture size for one color channel is smaller than that for the other two. This produces an image where different color channels have different depths-of-field, and from this we can computationally recover scene depth, reconstruct an all-focus image and achieve synthetic re-focusing, all from a single shot. These capabilities are enabled by a spatio-spectral image model that encodes the statistical relationship between gradient profiles across color channels. This approach substantially improves depth accuracy over alternative single-shot coded-aperture designs, and since it avoids introducing additional spatial distortions and is light efficient, it allows high-quality deblurring and lower exposure times. We demonstrate these benefits with comparisons on synthetic data, as well as results on images captured with a prototype lens.

The radio frequency window of the Square Kilometre Array is planned to cover the wavelength regime from cm up to a few meters. For this range to be optimally covered, different antenna concepts are considered enabling many science cases. At the lowest frequency range, up to a few GHz, it is expected that multi-beam techniques will be used, increasing the effective field-of-view to a level that allows very efficient detailed and sensitive exploration of the complete sky. Although sparse narrow band phased arrays are as old as radio astronomy, multi-octave sparse and dense arrays now being considered for the SKA, requiring new low noise design, signal processing and calibration techniques. These new array techniques have already been successfully introduced as phased array feeds upgrading existing reflecting telescopes and for new telescopes to enhance the aperture efficiency as well as greatly increasing their field-of-view (van Ardenne et al., Proc IEEE 97(8):2009) by [1]. Aperture arrays use phased arrays without any additional reflectors; the phased array elements are small enough to see most of the sky intrinsically offering a large field of view.

Intensity modulated radiation therapy (IMRT) remains the prevailing radiation treatment modality for localized prostate cancer. However, IMRT has three pronounced deficiencies: an elevated MU, a reduced MU-to-c-Gy coefficient, and the inability to track target motion. To address these issues, we have developed a novel radiation treatment technique, called the image-guided volumetric modulated radiation therapy (IG-VMAT) for the treatment of localized prostate cancer. In IG-VMAT approach, the image-guided target localization is achieved through point-based image registration using implanted gold-seed markers as a similarity measure, MU reduction is realized by using beam aperture-based inverse optimization, and the desired dose distribution is obtained through a synergistic modulation of MLC linear speed, temporal dose rate, and LINAC gantry angular speed. Our preliminary clinical data indicate that IG-VMAT can produce equal or better treatment plans than IMRT, reduce mean beam-on time by 45.8%, and achieve 1 mm accuracy in target localization.

This chapter is about the physical limitations of optical 3D sensors. The ultimate limit of the measurement uncertainty will be discussed; in other words: “How much 3D information are we able to know?” The dominant sources of noise and how this noise affects the measurement of micro-scale topography will be discussed. Some thoughts on how to overcome these limits will be given. It appears that there are only four types of sensors to be distinguished by the dominant sources of noise and how the physical measurement uncertainty scales with the aperture or working distance. These four types are triangulation, coherence scanning interferometry at rough surfaces, classical interferometry and deflectometry. 3D sensors will be discussed as communication channels and considerations about information-efficient sensors will be addressed.

Automotive antennas are usually realized as conformal antennas that are placed on the car glazing. Therefore they reside in the apertures of the metallic car body. In a simplified representation the passenger cabin is an absorbing cavity which features one or more apertures.

Results in theory of compressive sensing enable the reconstruction of sparse signals from a small set of non-adaptive linear measurements by solving a convex optimization problem. Considering the sparse structure of actual target space in Ground Penetrating Radar (GPR) application, a data acquisition method based on random aperture compressive sensing (RACS) is studied in this paper, which requires the GPR transceiver to record only a minimum amount of samples through incoherent measurement at each aperture point, and only to measure a small number of random apertures in x-y plane of interested target space. Results indicate that the method allow much fewer sampling data.

By augmenting a high resolution full-field Amplitude Modulated Continuous Wave lidar system with a coded aperture, we show that depth-of-field can be extended using explicit, albeit blurred, range data to determine PSF scale. Because complex domain range-images contain explicit range information, the aperture design is unconstrained by the necessity for range determination by depth-from-defocus. The coded aperture design is shown to improve restoration quality over a circular aperture. A proof-of-concept algorithm using dynamic PSF determination and spatially variant Landweber iterations is developed and using an empirically sampled point spread function is shown to work in cases without serious multipath interference or high phase complexity.

The laser communication provides very high bandwidth enabling real time transmission of data, voice and video through free space. We have designed a laser transmitter which can switch at 155 Mbps [E3,T3,FE,ATM, OC-3/STM-1] with average power of 10-30mw across all frequency range upto 155Mbps, further the circuit incorporates safety of ESD(electro static discharge), slow start, over current protection and temp control. The receiver has been tested independently and in an integrated setup (with transmitter) starting from APD, comparator and pulse shaping circuit by stimulated input. The power budget is calculated for the link taking into account fade margin(Tx power, Rx aperture, Rx sensitivity, atmospheric losses due to absorption, scattering, scintillation etc).The optical lenses will be utilized to make the beam divergent limited and for focusing the light onto the receiver active area.

The concept and design of a low cost two-axes MEMS scanning mirror with an aperture size of 7 millimetres for a compact automotive LIDAR sensor is presented. Hermetic vacuum encapsulation and stacked vertical comb drives are the key features to enable a large tilt angle of 15 degrees. A tripod MEMS mirror design provides an advantageous ratio of mirror aperture and chip size and allows circular laser scanning.

Depth from defocus (DFD) is a technique to recover the scene depth from defocusing in images. DFD usually involves two differently focused images (near-focused and far-focused) and calculates the size of the depth blur in the captured images. In recent years, the coded aperture technique, which uses a special pattern for the aperture to engineer the point spread function (PSF), has been used to improve the accuracy of DFD estimation. However, coded aperture sacrifices an incident light and loses a SNR of captured images which is needed for the accurate estimation. In this paper, we propose a new computational imaging, called half-sweep imaging. Half-sweep imaging engineers PSFs for improving DFD and maintaining the SNR of captured images. We confirmed the advantage of the imaging in comparison with conventional DFD and coded aperture in experiments.

It is well known that contamination of CT data with scattered radiation reduces reconstructed CT numbers and introduces cupping artifacts in the reconstructed images. This effect is more pronounced in multi detector CT scanners with extended detector aperture mostly using cone-beam configurations, which are much less immune to scatter than fan-beam and single-slice CT scanners. Accurate characterization of scattered radiation behavior is mandatory for implementation of robust and accurate scatter correction strategies in volumetric CT reconstruction. As characterization of scattered radiation behavior using experimental measurement is a difficult and time consuming approach, Monte Carlo simulation can be an ideal calculation method. In this study we used recently released GATE MC Code with the ability of CT simulation for characterization of scattering in volumetric GE 64 slice CT scanner. The Monte Carlo simulation was validated through comparison with experimental measurement data. Thereafter, the effect of tube voltage and Scatter to Primary Ratio (SPR) was calculated. The results indicate that the GATE Monte Carlo code is a useful tool for investigation of scattered radiation characterization in CT scanners. Moreover, there is a possibility of take advantage of GATE for simulation of PET scanners in order to simultaneously asses the contribution of scattered radiation in PET/CT scanners.

The last but not the least application of near-space vehicles in remote sensing is the Ground moving target indication (GMTI). In this chapter, we aim at MIMO SAR-based solution for GMTI including image formation processing. GMTI using MIMO SAR is interesting because the target indication performance can be improved by MIMO SARs’ larger virtual aperture. The minimum detectable velocity of a target can be improved by both the larger virtual aperture size and the longer coherent processing interval used by MIMO SARs.

In general, a material is classified as porous if its crystal structure is crossed by channels with a free aperture (effective channel width=ecw) at least 3.2A wide, such that the nitrogen molecule, N2, can pass through. In oxysalts, the ecw is calculated by subtracting the ionic diameter of O2− (2.8A) to the O…O distances across the channel (McCusker et al. 2003).

We propose a new imaging method called hemispherical confocal imaging to clearly visualize a particular depth in a 3-D scene. The key optical component is a turtleback reflector which is a specially designed polyhedral mirror. By combining the turtleback reflector with a coaxial pair of a camera and a projector, many virtual cameras and projectors are produced on a hemisphere with uniform density to synthesize a hemispherical aperture. In such an optical device, high frequency illumination can be focused at a particular depth in the scene to visualize only the depth with descattering. Then, the observed views are factorized into masking, attenuation, and texture terms to enhance visualization when obstacles are present. Experiments using a prototype system show that only the particular depth is effectively illuminated and hazes by scattering and attenuation can be recovered even when obstacles exist.

International audience; Partial isovists fields are useful methods to analyze the urban morphology taking into account the visual perception of the pedestrian. However, as previous studies involve a constant visual aperture angle all along the pathway, this paper presents an adaptative method of aperture angular variation according to urban morphology properties. Aperture angle increasing, nearby a square or at roads junction, or decreasing within a canyon street should improve the micro-behavior visual perception in our simulations. With showing that traditional isovist's shape indicators are not well adapted to achieve urban environmental properties, the aim of this paper is to present this new methodology based on a statistics standardized moment called Kurtosis. Our results show that this method could be used to define a surrounding space typology, one step more towards the modeling of visual dynamics.

Propagating through space, light carries with it the information on the shape and the spectrum of the source. A straightforward way to extract this information is an optical system that forms an image, reproducing the source’s spatial and spectral intensity distribution. However, there is a limit to the level of detail that can be resolved in the image of the source both due to fundamental physical boundaries – the diffraction at the aperture – and due to atmospheric turbulence.

So far, we have discussed the propagation of light – of the amplitude and of the coherence function – through free space, from an incoherent light source at a very large distance to the plane of observation, and its diffraction at single and multiple apertures. We introduced Young’s experiment as an instrument to measure the coherence function by determining contrast and position of the diffraction fringes. In Sect. 2.2, the diffraction of light at an aperture was investigated, and the case of an optical system was made by introducing the lens.

This paper presents an imaging arterial pulse oximeter based on the acquisition of two images respectively at the peak and trough a local arterial pulse. Spectroscopic sensitive images are obtained using a multi-aperture system synchronized to a point pulse oximeter. Each acquired image consists of 16 spectroscopic images of the same field of view. By subtracting the images obtained at the peak and trough of the arterial pulse one is able to eliminate common absorbers and scatterers and ultimately focus only on the metric of interest.