Rectangular Target Research Articles

Free-form lens for rectangular illumination with the target plane rotating at a certain angle.

We have proposed a method for rectangular illumination in a (u, v) coordinate system with high collection efficiency and favorable uniformity. In our proposed approach, with the target plane rotating at a certain angle around the z axis, one of the diagonals on the rectangular target plane moves to the coordinate axis; then, we partition the light source and target plane into grids. The intersection points of the grids are in one-to-one correspondence from the source to the target plane. This improved method will avoid the one-to-many correspondence topological relationship in the traditional (u, v) mapping method; uniformity of the illuminance pattern will be promoted. Based on this method, lenses are designed for rectangular target plane illumination; uniformity over 0.83 and efficiency of about 0.92 are obtained with a 1 mm×1 mm LED Lambertian source.

Temperature-Insensitive Hydrogen Sensor With Polarization-Maintaining Photonic Crystal Fiber-Based Sagnac Interferometer

We demonstrated a temperature-insensitive hydrogen ( $H_{2}$ ) sensor based on polarization-maintaining photonic crystal fiber (PM-PCF). The sensing element is a section of PM-PCF coated with Pd/Ag composite film and is incorporated into a single mode fiber Sagnac loop interferometer. The birefringence of PM-PCF is modulated by $H_{2}$ absorption that induces deformation of the Pd/Ag composite film, resulting in shift of the interference spectrum at the output of the Sagnac interferometer. A magnetron facing target sputtering technique with special Pd/Ag rectangular target structures is developed to deposit Pd/Ag composite film on the cylindrical surface of the PM-PCF and the atomic ratio of Pd/Ag composite film is controlled by setting appropriate volume ratio in rectangular target. An empirical linear relationship between atomic ratio and volume ratio was obtained and the $H_{2}$ sensing capacity with different atomic ratio of Pd/Ag composite films was investigated experimentally. The results showed that increasing the proportion of Pd in the composite film improves the $H_{2}$ detection sensitivity. The sensitivity can also be improved by using as longer length of Pd/Ag coated PM-PCF. With ∼100 mm long coated PM-PCF as the sensing element, we obtained ∼1.310 nm shift in the interference spectrum for $H_{2}$ concentration from 0 to 1%. The sensitivity coefficient is ∼131 pm% in the range of 1% to 4% $H_{2}$ concentration. The sensor has low temperature dependence and good repeatability.

Naval ship's susceptibility assessment by the probabilistic density function

Abstract The survivability of the naval ship is the capability of a warship to avoid or withstand a hostile environment. The survivability of the naval ship assessed by three categories (susceptibility, vulnerability and recoverability). The magnitude of susceptibility of a warship encountering with threat is dependent upon the attributes of detection equipment and weapon system. In this paper, as a part of a naval ship's survivability analysis, an assessment process model for the ship's susceptibility analysis technique is developed. Naval ship's survivability emphasizing the susceptibility is assessed by the probability of detection, and the probability of hit. Considering the radar cross section (RCS), the assessment procedure for the susceptibility is described. It's emphasizing the simplified calculation model based on the probability density function for probability of hit. Assuming the probability of hit given a both single-hit and multiple-hit, the susceptibility is accessed for a RCS and the hit probability for a rectangular target is applied for a given threat.

Experimental and simulated validation of the energy dependence of saturation thickness of multiple scattered gamma rays

Abstract Saturation thickness for multiple scattering gamma rays from multiple sources has been measured experimentally and simulated using the Monte Carlo N-Particle (MCNP) Code. Experimental measurements were performed using a collimated beam of gamma-rays from 57Co, 203Hg, 133Ba, 22Na, 137Cs, 65Zn and 60Co sources. The gamma rays were directed at rectangular aluminium targets of varying thickness. A NaI (Tl) scintillation detector placed at a backscattering angle of 180° was used to detect the scattered photons. The measured and calculated saturation thickness increases with increasing energy of incident gamma-rays. Experimental and simulated values are compared and are in good agreement.

Variable slice-thickness (VAST) EPI for the reduction of signal voids in GE-EPI at 7 Tesla

2D gradient-echo EPI of the human brain suffers from signal loss artifacts caused by susceptibility-induced gradients perpendicular to the slice plane. The problem is most pronounced near the skull's air cavities and compromises BOLD fMRI studies in regions including orbito-frontal and temporal cortex. The spins across the excited rectangular target slice profile are effectively dephased by through-plane gradient GS,z as can be seen for two slices in Fig 1 at 7 T. According to the expression on the right (see Fig 1) many methods exist to address the issue, including z-shimming[1], tailored RF excitations[2], short or slice-dependent TE[3] and the use of thin slices for a defined region[4]. The drawback is that optimizing parameters for a certain region will compromise sensitivity elsewhere and result in unfeasibly long TR for whole brain coverage. Hence, we propose a new technique dubbed 'Variable SliceThickness EPI' (VAST EPI) to reduce signal loss and keeping TR manageable in 2D GE-EPI. The slice thickness is varied across the brain, with thinner slices being used in the inferior regions where signal voids are most severe. Various scheme of slice thickness variation are evaluated and compared to regular EPI.

Reaction time in ankle movements: a diffusion model analysis.

Reaction time (RT) is one of the most commonly used measures of neurological function and dysfunction. Despite the extensive studies on it, no study has ever examined the RT in the ankle. Twenty-two subjects were recruited to perform simple, 2- and 4-choice RT tasks by visually guiding a cursor inside a rectangular target with their ankle. RT did not change with spatial accuracy constraints imposed by different target widths in the direction of the movement. RT increased as a linear function of potential target stimuli, as would be predicted by Hick-Hyman law. Although the slopes of the regressions were similar, the intercept in dorsal-plantar (DP) direction was significantly smaller than the intercept in inversion-eversion (IE) direction. To explain this difference, we used a hierarchical Bayesian estimation of the Ratcliff's (Psychol Rev 85:59, 1978) diffusion model parameters and divided processing time into cognitive components. The model gave a good account of RTs, their distribution and accuracy values, and hence provided a testimony that the non-decision processing time (overlap of posterior distributions between DP and IE < 0.045), the boundary separation (overlap of the posterior distributions < 0.1) and the evidence accumulation rate (overlap of the posterior distributions < 0.01) components of the RT accounted for the intercept difference between DP and IE. The model also proposed that there was no systematic change in non-decision processing time or drift rate when spatial accuracy constraints were altered. The results were in agreement with the memory drum hypothesis and could be further justified neurophysiologically by the larger innervation of the muscles controlling DP movements. This study might contribute to assessing deficits in sensorimotor control of the ankle and enlighten a possible target for correction in the framework of our on-going effort to develop robotic therapeutic interventions to the ankle of children with cerebral palsy.

Optimum Angle of attack for a Rectangular Target

The optimum angles of attack for a rectangular target along with the necessary conditions are discussed.

Small grain size zirconium-based coatings deposited by magnetron sputtering at low temperatures

Hard, partly amorphous, ZrTiB(N) coatings were deposited by Physical Vapour Deposition (PVD) onto (111) silicon wafers at low substrate temperatures of 85 and 110°C using Closed Field Unbalanced Magnetron Sputtering. A segmented rectangular sputter target composed of three pieces (Zr/TiB2/Zr) was used as the source of evaporation of coating components. Two different substrate biases (i.e. floating potential and −50V) and N2 reactive-gas flow rates of 2, 4 and 6sccm were employed as the main deposition parameter variables.The chemical composition, structure, morphology and mechanical properties were investigated using a variety of analytical techniques such as Glow-Discharge Optical Emission Spectroscopy, cross-sectional Scanning Electron Microscopy (SEM), Glancing Angle X-ray Diffraction (GAXRD) and nanoindentation. With other parameters fixed, coating properties were found to be dependent on the substrate negative bias and nitrogen flow rate. Linear scan profiles and SEM imaging revealed that all coatings were smooth, dense and featureless (in fracture cross section) with no apparent columnar morphology or macro-defects. GAXRD structural analysis revealed that mostly metallic phases were formed for coatings containing no nitrogen, whereas a solid solution (Zr,Ti)N single phase nitride was found in most of the reactively deposited coatings — exhibiting a very small grain size due to nitrogen and boron grain refinement effects.Hardness values from as low as 8.6GPa up to a maximum of 25.9GPa are related mainly to solid solution strengthening effects. The measured elastic moduli correlated with the trends in hardness behaviour; values in the range of 120–200GPa were observed depending on the selected deposition parameters. Also, high H/E values (>0.1) were achieved with several of the coatings.

Distortion Calibration for Camera Lens Based on Digital Image Processing

Distortion produced by optical system makes the image of object in linear CCD deviate from the theoretical point and lead to the system measuring error. According to the digital image processing, a high-precision calibration method is proposed. The imaging measurement system is calibrated through two steps: firstly, use laser collimation to detect the principal point for a large visal field camera lens with short focal distance. Secondly, use a rectangular gidding target to get lens distortion coefficient.

An investigation of energy dependence on saturation thickness for 59.54, 123, 279, 360, 511, 662, 1115 and 1250 keV gamma photons in carbon and aluminium

Multiple back-scattering of gamma photons from carbon and aluminium targets is studied with a view to estimate energy dependence on saturation thickness. The number of multiple backscattered photons increases with an increase in the target thickness and then saturates at a particular thickness called the saturation thickness. An intense collimated beam, obtained from 241Am, 57Co, 203Hg, 133Ba, 22Na, 137Cs, 65Zn and 60Co sources, is allowed to impinge on rectangular carbon and aluminium targets of varying thickness. The scattered photons from the samples are detected by a 76mm×76mm NaI (Tl) scintillation detector placed at a backscattering angle of 135°. The measured saturation thickness for multiple backscattering of gamma photons is found to be increasing with an increase in the energy of incident gamma photons. The experimental results are compared with Monte Carlo calculations carried out using the Monte Carlo N-Particle (MCNP) simulation code.

Simultaneous encoding of the direction and orientation of potential targets during reach planning: evidence of multiple competing reach plans

Reaches performed in many natural situations involve selecting a specific target from a number of alternatives. Recent studies show that before reaching, multiple potential reach targets are encoded in brain regions involved in action control and that, when people are required to initiate the reach before the target is specified, initial hand direction is biased by the spatial distribution of potential targets. These findings have led to the suggestion that the brain, during planning, simultaneously prepares multiple reaches to potential targets. In addition to hand direction, reach planning often involves specifying other parameters such as wrist orientation. For example, when posting a letter in a mail slot, both the location and orientation of the slot must be encoded to control hand direction and orientation. Therefore, if the brain prepares multiple reaches to potential targets and if these targets require the specification of hand direction and orientation, then both of these variables should be biased by the spatial distribution of potential targets. To test this prediction, we examined a task in which participants moved a hand-held rectangular tool toward multiple rectangular targets of varying location and orientation, one of which was selected, with equal probability as the actual target after movement initiation. We found that initial hand direction and orientation were biased by the spatial distributions of potential target locations and orientations, respectively. This result is consistent with the idea that the brain, in cases of target uncertainty, simultaneously plans fully specified reaching movements to all potential targets.

Magnetron Sputtering Target Structure Optimization Research Status

In order to optimize the target surface magnetic field intensity and uniformity for the purpose, this paper introduces the traditional magnetron sputtering target problems, the author summarizes the other researchers on magnetron sputtering target field overall optimization ideas, magnetic field simulation method and different target under the condition of the magnet structure optimization, especially in rectangular target end area optimization are summarized, and the magnetron sputtering target magnetic field pole shoe and permeability piece optimization also made a description.

Assessment of the test–retest reliability of a foot placement accuracy protocol in assisted-living older adults

IntroductionThis study assessed the test–retest reliability of a foot placement accuracy protocol in a population of assisted-living elderly. The goal was to evaluate the execution of foot placement performance with increasing complexity of the walking condition. MethodsTwenty-five elderly participants (5 males, 20 females, 80.4±8.6 years) were assessed by one observer in two sessions with 48h between the measurements. Participants walked at self-selected pace along a pathway with three different walking conditions composed of two rectangular foam target locations and an obstacle on the walking surface. The main outcome measures were foot placement distance error, intra-class correlation coefficients (ICC), and the smallest detectable difference (SDD). ResultsMean absolute values of the foot placement distance errors were 14.0±4.5mm for medio-lateral deviation and 27.2±2.1mm for anterior–posterior deviation, respectively. ICC values for test–retest reliability showed ‘fair to good’ to ‘excellent’ reliability across all conditions with values ranging from 0.63 to 0.94. SDD values were between 3.6 and 37.3mm. ConclusionThe protocol showed good reliability for test–retest measurements of foot placement accuracy, thus making this protocol a reliable and location-independent tool to assess performance of foot placement in elderly in assisted-living settings. In the future, measurements with elderly fallers and non-fallers should be conducted to assess validity of the protocol.

Commissioning dose computation models for spot scanning proton beams in water for a commercially available treatment planning system

To present our method and experience in commissioning dose models in water for spot scanning proton therapy in a commercial treatment planning system (TPS). The input data required by the TPS included in-air transverse profiles and integral depth doses (IDDs). All input data were obtained from Monte Carlo (MC) simulations that had been validated by measurements. MC-generated IDDs were converted to units of Gy mm(2)/MU using the measured IDDs at a depth of 2 cm employing the largest commercially available parallel-plate ionization chamber. The sensitive area of the chamber was insufficient to fully encompass the entire lateral dose deposited at depth by a pencil beam (spot). To correct for the detector size, correction factors as a function of proton energy were defined and determined using MC. The fluence of individual spots was initially modeled as a single Gaussian (SG) function and later as a double Gaussian (DG) function. The DG fluence model was introduced to account for the spot fluence due to contributions of large angle scattering from the devices within the scanning nozzle, especially from the spot profile monitor. To validate the DG fluence model, we compared calculations and measurements, including doses at the center of spread out Bragg peaks (SOBPs) as a function of nominal field size, range, and SOBP width, lateral dose profiles, and depth doses for different widths of SOBP. Dose models were validated extensively with patient treatment field-specific measurements. We demonstrated that the DG fluence model is necessary for predicting the field size dependence of dose distributions. With this model, the calculated doses at the center of SOBPs as a function of nominal field size, range, and SOBP width, lateral dose profiles and depth doses for rectangular target volumes agreed well with respective measured values. With the DG fluence model for our scanning proton beam line, we successfully treated more than 500 patients from March 2010 through June 2012 with acceptable agreement between TPS calculated and measured dose distributions. However, the current dose model still has limitations in predicting field size dependence of doses at some intermediate depths of proton beams with high energies. We have commissioned a DG fluence model for clinical use. It is demonstrated that the DG fluence model is significantly more accurate than the SG fluence model. However, some deficiencies in modeling the low-dose envelope in the current dose algorithm still exist. Further improvements to the current dose algorithm are needed. The method presented here should be useful for commissioning pencil beam dose algorithms in new versions of TPS in the future.

Formation of 3D wedge-shaped electron beams

The paper presents the paraxial approximation of the solution to the problem on the electron beam formation as an arbitrary cut from a flow in a cylindrical diode, in particular, with a cross section close to a rounded rectangle with a large half-side ratio (wide beams) in situations when a converging or diverging electron flow acts on rectangular targets. The approximation is obtained with allowance for the cathode singularity.

Control of cathodic arc spot motion under external magnetic field

A closed circular transverse magnetic field is designed to control the spot motion of a cathodic arc on a large rectangular target. Stable and controllable spot motion is observed from both graphite and copper. The arc stability, spot velocity, and etched pattern on the cathode surface are studied systematically. Circular tracks are etched on the target surface by the repetitive spot movement and the surface morphology and resistivity of the cathode materials influence the spot velocity.

The influence of extrafoveal emotional faces on prosaccade latencies

Across three experiments we sought to determine whether extrafoveally presented emotional faces are processed sufficiently rapidly to influence saccade programming. Two rectangular targets containing a neutral and an emotional face were presented either side of a central fixation cross. Participants made prosaccades towards an abrupt luminosity change to the border of one of the rectangles. The faces appeared 150 ms before or simultaneously with the cue. Saccades were faster towards cued rectangles containing emotional compared to neutral faces even when the rectangles were positioned 12 degrees from the fixation cross. When faces were inverted, the facilitative effect of emotion only emerged in the −150 ms SOA condition, possibly reflecting a shift from configural to featural face processing. Together the results suggest that the human brain is highly specialized for processing emotional information and responds very rapidly to the brief presentation of expressive faces, even when these are located outside foveal vision.

Novel Surface-Mounted Neutron Generator

A deuterium-tritium base reaction pulsed neutron generator packaged in a flat computer chip shape of 1.54 cm (0.600 in) wide by 3.175 cm (1.25 in) long and 0.3 cm (0.120 in) thick has been successfully demonstrated to produce 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> neutrons per pulse (14 MeV) in a 0.5- μs pulse. The neutron generator is based on a deuterium ion beam accelerated to impact a tritium-loaded target. The accelerating voltage is in the 15- to 20-kV range with a 3-mm (0.120 in) gap, and the ion beam is shaped by using a lens design to produce a flat ion beam that conforms to the flat rectangular target. The ion source is a simple surface-mounted deuterium-filled titanium film with a fused gap that operates at a current-voltage design to release the deuterium during a pulselength of about 1 μs. We present some of the preliminary results and the general description of the working prototypes, which we have labeled the “NEUTRISTOR.”

Out-of-field dose measurements in a water phantom using different radiotherapy modalities

This investigation focused on the characterization of the lateral dose fall-off following the irradiation of the target with photons, protons and carbon ions. A water phantom was irradiated with a rectangular field using photons, passively delivered protons as well as scanned protons and carbon ions. The lateral dose profile in the depth of the maximum dose was measured using an ion chamber, a diamond detector and thermoluminescence detectors TLD-600 and TLD-700. The yield of thermal neutrons was estimated for all radiation types while their complete spectrum was measured with bubble detectors during the irradiation with photons. The peripheral dose delivered by photons is significantly higher compared to both protons and carbon ions and exceeds the latter by up to two orders of magnitude at distances greater than 50 mm from the field. The comparison of passive and active delivery techniques for protons shows that, for the chosen rectangular target shape, the former has a sharper penumbra whereas the latter has a lower dose in the far-out-of-field region. When comparing scanning treatments, carbon ions present a sharper dose fall-off than protons close to the target but increasing peripheral dose with increasing incident energy. For photon irradiation, the contribution to the out-of-field dose of photoneutrons appears to be of the same order of magnitude as the scattered primary beam. Charged particles show a clear supremacy over x-rays in achieving a higher dose conformality around the target and in sparing the healthy tissue from unnecessary radiation exposure. The out-of-field dose for x-rays increases with increasing beam energy because of the production of biologically harmful neutrons.

기상 상태 변화에 따른 직육면체의 재질별 표면온도 변화 특성에 대한 실험 연구

The spectral radiance received by a remote sensor is consisted of the self-emitted component directly from the target surface, the reflected component of the solar irradiance at the target surface, and the scattered component by the atmosphere without ever reaching the object surface. In general, the self-emitted component is the most important part in the infrared signatures from the target. We measured the solar irradiation, sky irradiation, air temperature, wind velocity, wind direction, relative humidity, and atmospheric pressure together with the surface temperatures of rectangular parallelepiped targets. The measured diurnal surface temperature variations on the three different rectangular parallelepiped targets constructed by the steel, aluminum and bakelite are obtained at the same time intervals. The measured surface temperature results show that the top surface temperature of bakelite recorded up tp higher than that of aluminium and higher than that of steel at 11 AM on the sunny condition. A complete set of measured data including the surface temperature of rectangular parallelepiped targets together with the detailed weather information can be a valuable reference for future study.