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The intensities and phase profiles of the elliptic optics vortex beam both are determined by the topological charge (TC) and ellipticity. This paper presents an efficient and simple method for measuring the TC and ellipticity of elliptic vortex. By observing the diffraction patterns, the TC modulus and ellipticity can be probed with the suitable rectangular aperture, and the TC sign can be detected with the suitable right triangular aperture. The scheme works well even for high-order elliptic vortex with topological charge value as high as ± 18, and ellipticity range from 0.5 to 2 at least. Obviously, the measurement of TC and ellipticity have important research value for promoting the application of elliptical vortex.

During the long service period of a nuclear waste repository in crystalline rock, large earthquake(s) may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures within the geological formation. The resulting fracture normal/shear displacements may lead to fracture opening and further promote the transport of leaked radionuclides into the groundwater system. Thus, it is of central importance to analyze the consequences of potential future earthquake(s) on the hydrogeological properties of a repository site for spent nuclear fuel disposal. Based on the detailed site characterization data of the repository site at Forsmark, Sweden, we conduct a three-dimensional (3D) seismo-hydro-mechanical simulation using the 3Dimensional Distinct Element Code (3DEC). We explicitly represent a primary seismogenic fault zone and its surrounding secondary fracture network associated with a power-law size scaling and a Fisher orientation distribution. An earthquake with a magnitude of Mw = 5.6 caused by the reactivation of the primary fault zone is modeled by simulating its transient rupture propagating radially outwards from a predefined hypocenter at a specified rupture speed, with the faulting dynamics controlled by a strength weakening law. We model the coseismic response of the off-fault fracture network subject to both static and dynamic triggering effects. We further diagnose the distribution of fracture hydro-mechanical properties (e.g. mechanical/hydraulic aperture, hydraulic transmissivity) before and after the earthquake in order to quantify earthquake-induced hydraulic changes in the fracture network. It is found that earthquake-induced fracture transmissivity changes tend to follow a power-law decay with the distance to the earthquake fault. Our simulation results and insights obtained have important implications for the long-term performance assessment of nuclear waste repositories in fractured crystalline rocks., Journal of Rock Mechanics and Geotechnical Engineering, ISSN:1674-7755, ISSN:2589-0417

A low-profile high efficiency transmitarray antenna (TA) using an optimized phase compensation surface (PCS) and PEC sidewalls is proposed in this paper. Generally, TAs are composed of a source antenna and a planar PCS, and the PCS makes the phase of transmitted wave through the PCS be in-phase, resulting in a highly directive beam. The unit cells of a PCS cannot have a 100% transmittance at all transmission phases. Since there may be combinations of PCS that make various in-phases, the transmit efficiency of the TA can be improved. Also, the four PEC sidewalls are employed to maximize the amount of power reaching the PCS from the source antenna. As a result, the 100% spillover efficiency is achieved without diminishing taper efficiency. To verify its feasibility, the square TA was designed and measured at 5.8 GHz and a high aperture efficiency of 54% was obtained through the above design methodology.

A convenient approach was proposed by which to evaluate and monitor the permeability of a rock fracture by verifying the quantitative correlation between the electrical resistivity and permeability at laboratory scale. For this purpose, an electrical resistivity measurement system was applied to the laboratory experiments using artificial cells with the shape of a single rock fracture. Sixty experiments were conducted using rock fractures according to the geometry, aperture sizes, wavelengths, and roughness amplitudes. The overall negative relationship between the normalized electrical resistivity values and the aperture sizes directly linked with the permeability, was well fitted by the power-law function with a large determination coefficient (≈0.86). The effects of wavelength and roughness amplitude of the rock fracture on the electrical resistivity were also analyzed. Results showed that the electrical resistivity was slightly increased with decreasing wavelength and increasing roughness amplitude. An empirical model for evaluating the permeability of a rock fracture was proposed based on the experimental data. In the field, if the electrical resistivity of pore groundwater could be measured in advance, this empirical model could be applied effectively for simple, quick monitoring of the fracture permeability. Although uncertainty may be associated with the permeability estimation due to the limited control parameters considered in this research, this electrical resistivity approach could be helpful to monitor the rock permeability in deep underground facilities such as those used for radioactive waste repositories or forms of energy storage.

In this paper, a novel 2-DOF rotational pointing mechanism (RPM) is designed inspired by the guidelines of the graphical approach. The mechanism integrates with a fast steering mirror (FSM) for compensating pointing errors of a laser beam. The design intends to achieve an angular travel of ±10 mrad and steers a 25 mm mirror aperture. A planar flexure with beam flexures accompanied in parallel with an axial flexure build-up mechanism configuration. Compliant mechanism-based RPM ensures high precision and compactness. Compliance characteristics are established based on the stiffness matrix method for four different planar flexure layouts. One layout with best in-plane rotational compliance is then assessed for performance sensitivity to mechanism dimension parameters and parasitic error, thus informing the design space. Rotational stiffness in both the in-plane rotational axes and stress is determined based on finite element analysis (FEA). The wire electrical discharge machining (EDM) is employed for developing the proof of concept for the RPM and is then assembled in FSM. Experiments are conducted to determine the rotational stiffness and angular travel about both in-plane rotational axes. Comparison among theoretical, numerical and experiments reveal excellent linearity of rotational stiffness along the rotational travel range. The maximum theoretical error is less than 5.5% compared with FEA while, the experimental error has a mean of 5% and 3% for both rotational axes thus satisfying the intended design requirement.

This work is devoted to develop the theory of concentration distribution of radiation over the receiver surface in cylindrical parabolic concentrator of radiation with axisymmetrical (cylindrical) radiation receiver has been studied. The results will make it possible to estimate concentration distribution over the radiation receiver surface and to associate output characteristics of concentrator unit for various combinations of design parameters at the stage of engineering, to choose the best combination of such parameters and to optimize reflecting surface and radiation receiver. Photovoltaic module with cooling or without it, solar collector, photovoltaic thermal module, etc. may be applied as radiation receivers. Mathematical physics equations have been deduced that describe the specifics of incident radiation flux reflection from the concentrator’s surface and falling onto that of radiation receiver. Concentration distribution has been estimated, for various concentrator design parameters and various positions of receiver axis in relation to the focus of reflecting surface, on the symmetry plane. The most effective concentrator designs characterized by 100% optical efficiency correspond to options where the focus of concentrator’s reflecting surface is located inside radiation receiver. Analysis of design options using the developed theory is shown on examples for given values of average concentration ratio (2, 6, 8, 10, 15, 20, 50), as well as radius of radiation receiver, half concentrator aperture and distance between the focus line and the symmetry axis of radiation receiver in cross-section.

This paper describes the imaging performance of a high-field in-line MRI linear accelerator with a patient rotation system in-situ. Signal quality was quantified using signal-to-noise ratio (SNR) and RF uniformity maps. B0-field inhomogeneity was assessed using magnetic field mapping. SNR was evaluated with various entries into the Faraday cage which were required for extended couch translations. SNR varied between 103 and 87 across PRS rotation angles. Maximum B0-field inhomogeneity corresponded to 0.7 mm of geometric distortion. A 45 × 55 cm2 aperture allowed PRS translation with no reduction in SNR. Imaging performance with the PRS in-situ was found to be acceptable.

This work investigates the performance of a conventional steam power plant retrofitted with a solar-assisted regenerative system using Parabolic Trough Solar Collectors (PTC). The solar collectors were used to compensate for the effect of removing Low-Pressure (LP) turbine extractions without changing other elements of a 300 MW power plant unit during peak load operations. The steam power plant, located in Kuwait, receives high levels of solar irradiation. Modeling of the solar-assisted regenerative system using PTC is simulated for Kuwait’s weather conditions. Results of the system analysis show that removing the LP turbine extractions enhanced the performance of the steam power plant by 9.8 MW, with an optimum PTC aperture area equal to 25,850 m2. A techno-economic analysis was used to estimate the Levelized Cost of Energy (LCOE). Compared to an equivalent photovoltaic solar plant, the optimum aperture area and LCOE for the PTC solar plant were found to be less by 45% and 44%, respectively. When compared to an equivalent conventional steam turbine, the solar-assisted steam power plant decreased cost by 56% over the lifecycle of 25-years.

The study proposes a method for preliminary and estimative sizing of the main components of solar district heating systems, with seasonal thermal storage. The main parameters determined by this method, are the aperture area of the solar thermal collectors and the volume of the seasonal thermal storage. The proposed method is only estimative, but it provides the necessary input data for the investigation of the dynamic thermal behavior of such systems. The main advantage of the method is that it requires only very few and accessible input data. Two situations are considered: the first in which available climatic data such as annual global solar radiation on horizontal plane and annual average temperature can be used in calculations, and the second in which such data is not available and should be determined through interpolation. With the proposed interpolation functions the annual global solar radiation on horizontal plane, the annual average temperature and the annual global efficiency of the solar thermal collectors were determined. The errors of the estimations are ranging within the intervals of (-15.6 … +25.8) % for annual global solar radiation on horizontal plane and (-10.8 … 19.1) % for annual global efficiency of the solar thermal collectors. The maximum deviations for the annual average temperature estimations were (-4.23 … +5.37) °C. With this limited accuracy, the proposed interpolation functions can be used for latitudes between (0 - 70) °, annual global solar radiation on horizontal plane between (704 - 2337) kWh/m2/year and annual average temperatures ranging within the interval of (2 - 30) °C.

Absolute measurement technology has received considerable attention in the field of optical metrology owing to its high accuracy. However, to ensure accuracy of measurement, the traditional method requires the use of expensive high-precision stages and considerable time for the precise adjustment of the measured surface. A shift-rotation absolute measurement method for irregular aperture optical surfaces based on deep learning is presented here. In this method, the measured surface needs to be tested in the original position and two randomly changed positions. Furthermore, a simple and effective shift-rotation prediction convolutional neural network that can learn the mapping relationships between the binarized images of the changed position and shift-rotation is designed. The shape of the measured surface with an irregularly shaped aperture is obtained by fitting orthogonalized Zernike polynomials. Compared with the current absolute measurement method for irregular apertures, this method is highly efficient and cost-effective for adjusting the measured surface. The simulation and experimental results demonstrate the accuracy and validity of this approach.

Aperture averaging (AA) is a potential technique to reduce the effect of atmospheric turbulence in optical wireless communications (OWC). Although there is significant research on point-like detectors, there is a gap in the study on the analytical performance evaluation of OWC systems with AA over atmospheric turbulence and pointing errors. In this paper, we analyze the performance of a single-link OWC system by considering the three-parameter exponentiated Weibull (EW) model for the atmospheric turbulence and the zero boresight fading model for pointing errors. We derive analytical expressions for moments of signal-to-noise ratio (SNR), ergodic capacity, outage probability, average bit-error-rate (BER), and average energy consumption under the combined effect of atmospheric turbulence and pointing errors in terms of system parameters. To provide insights on the system behavior, we develop asymptotic bounds at high SNR on the performance of the considered system. We also derive analytical expressions for the performance of OWC system under the atmospheric turbulence with negligible pointing errors. We demonstrate the performance of OWC system over EW turbulence with a comparison to the performance obtained using the Gamma–Gamma (GG) model and demonstrate the tightness of the derived performance bounds through numerical and simulation analysis.

Electrochemical machining (ECM) is an important machining technique for the aeronautical manufacturing industry. Through-mask ECM is a form of ECM for machining metal parts with a hole array. In order to extend the machining area, a serpentine flow channel with multiple curves was used for through-mask ECM. With the extension of the flow channel, ensuring a machining consistency along the flow channel has been a challenge. The electrolyte conductivity is the main factor affecting the machining consistency. To analyze the change rules of the electrolyte conductivity, variations in the bubble rate and the temperature of the electrolyte in the electrolyte flow were explored under different power sources. Results indicate that pulse-power machining can reduce variations in the bubble rate and the temperature in the serpentine flow channel, and then the electrolyte conductivity can be stabilized within a very small range. Experiments using through-mask ECM were conducted in two types of power sources. Experimental results support the importance of pulse-power machining. A 14 × 28 hole array with a 2.5 mm diameter was fabricated by a pulsed power source. The aperture deviation of the hole array is less than 0.05 mm, and the roundness deviation is less than 15 μm when fabricated with pulse machining. Keywords: Hole array, Numerical simulation, Pulse machining, Serpentine flow channel, Through-mask electrochemical machining

The linear optical and electroluminescence properties of small molecular organic material tris-(8-hydroxyquinoline) aluminum (Alq3) are known and extensively investigated by many studies. However, the studies on the nonlinear optical (NLO) properties of this material are still scarce. Herein, the third-order NLO (TONLO) properties of Alq3 chloroform solutions with different concentrations have been examined using the Z-scan technique. At different laser powers and different laser wavelengths, the Z-scan signals were recorded using a continuous-wave (CW) laser beam. The open-aperture (OA) and closed- aperture (CA) Z-scan signals revealed strong TONLO properties. Both nonlinear refractive index (n2) and nonlinear absorption coefficient (β) showed negative values, and their smallest values were in the fold of 10−8 cm2/W and 10−2 cm/W, respectively. The negative values of n2 and β suggest thermal nonlinearity and saturable absorption (SA), respectively. The TONLO susceptibility (χ(3)) was calculated and found to be in the order of 10−6 esu. Besides, they increased with increasing the concentrations of Alq3 and laser powers. Therefore, the results indicate that Alq3 could be one of the potential materials as a saturable absorber for starting a passive mode-locking operation.

Purpose To report the clinical findings of the patients with retinal pigment epithelium (RPE) aperture secondary to age-related macular degeneration (AMD). Methods A retrospective data analysis was conducted of patients at the University of Tokyo Hospital eye clinic, from the year September 1st, 2012 to 2019. Review of the medical records of patients with RPE aperture accompanied by AMD was performed. We investigated age, best-corrected visual acuity (BCVA), images of spectral domain optical coherence tomography, short-wave fundus autofluorescence (FAF), fluorescein angiography (FA), indocyanine green angiography, and retinal sensitivity measured with microperimetry. The change in visual acuity or the area of the aperture during the follow-up period was analyzed. Results Five eyes of 5 patients (4 men, one woman) were included in the analysis. The mean age at presentation was 78.6 ± 9.1 years. The average length of follow-up was 23.6 ± 17.9 months. The RPE apertures appeared as round, either at the apex or at the base of PED, with no evidence of accompanying CNV but subretinal detachment (SRD) above the aperture. On FAF, the apertures appeared as sharply demarcated round areas of hypoautofluorescence. The FA revealed sharply demarcated round areas of window defects in the early and mid-phase with leakage in the late phase corresponding to SRD. The area of apertures enlarged during the follow-up period. Mean BCVA got worse from 0.20 logMAR at the initial presentation to 0.39 logMAR at the last visit. The retinal sensitivity was reduced but partly preserved above the area of aperture. Conclusions and importance RPE aperture was found in some patients with drusenoid PED secondary to AMD. It enlarged during follow-up. Visual acuity was declined. Retinal sensitivity was decreased but partly preserved.

For the ITER core CXRS diagnostic, a shutter is mandatory to protect the first mirror when no measurement takes place. With the continuing design development of the diagnostic and the knowledge obtained from previous shutter prototypes, the frictionless fast shutter did undergo some design changes and manufacturing improvements without degrading the performance (opening/closing 1 s). In this paper, the major modifications of the shutter design are presented. An adjustment system was developed to allow compensation of manufacturing deviations and precise positioning of the protective blade according to the final aperture position, which is not known before the final assembly with the as-built dimensions of the port plug and diagnostic shield module (DSM). The shutter components and their adjustment systems are implemented into the shutter‘s actively cooled base structure, which in turn simplifies the remote handling procedure. For the helium circuit an activity study is presented, which allows to access the nuclear pressure equipment classification and to determine the number of required purges during the ITER lifetime. With the heat loads obtained from the known heat flow on the blade and from the neutronics analysis, a thermal FE-analysis was performed on the full shutter model by which the expected heat flow at the mechanical interfaces can be given.

In this paper, a high-efficiency dual-polarized transmissive metasurface is presented for the generation of dual-mode convergent orbital angular momentum (OAM) beams. The proposed transmissive metasurface is composed of dual-polarized metasurface units, which are constructed from four stacked patches coupled through a Jerusalem-cross aperture on the interlayer ground, to complete the phase modulation for the orthogonal polarizations. The proposed transmissive metasurface units can achieve full 2π phase modulation along with low transmission loss. Converged OAM beams with modes numbers lx = +1 and ly = −2 are thus stimulated through the proposed transmissive metasurface for both orthogonal polarizations, which have been demonstrated numerically and experimentally.

Transmitted wavefronts are usually measured by a laser interferometer of the corresponding design wavelength. The Zernike coefficient can be used to describe the transmitted wavefront of a circular aperture. However, it has some limitations in optical systems with non-circular apertures. In this paper, a method, based on discrete points, for measuring transmitted wavefronts in a broad bandwidth is presented. Simulations of monochromatic, achromatic and apochromatic systems verify the method. The system with off-axis field of view is also analyzed. The Conrady dispersion formula and apochromatic characteristic formula (ACF) are used to represent the relationship between the optical path difference (OPD) at each discrete point of the transmitted wavefront and the wavelength. We also experimentally verify this method by measuring the wavefront of the optical system with a square aperture. The results demonstrate that the method can be used to measure the non-circular wavefront in a broad bandwidth.

In the frame of the EUROfusion Work Package Heating and Current Drive (WP HCD) of the Power Plant Physics and Technology (PPPT) program, CVD diamond disk Brewster-angle windows for gyrotron operation at multi-megawatt RF power levels and long pulses are under development. These windows allow for frequency step-tuneable operation. The Brewster-angle of 67.2° for diamond leads to an elliptical connection of the disk to the copper waveguides (WGs), requiring an advanced joining process. For proper transmission of the RF power, the disk consists of low loss CVD diamond of optical grade. The current target for the WG aperture of DEMO is 63.5 mm. It allows for an RF power transmission of 2 MW, but it requires a disk diameter of 180 mm for the 67.2° angle. In addition, a thickness of approximately 2 mm is needed to achieve the proper mechanical stability. State of the art microwave plasma reactors are not capable of growing disks of such size. The maximum available diameter of a polycrystalline CVD diamond disk suited to microwave applications is currently 140 mm. Thus, the industrial partner Diamond Materials GmbH (Freiburg, Germany) is doing extensive diamond growth experiments. A first of its kind, 180 mm thermal grade, crack-free, diamond disk was produced in the microwave plasma reactor with an average unpolished thickness of about 2 mm. First loss tangent measurements have been also performed. This paper describes the steps and the first results of this non-straightforward path, a challenging new field for diamond manufacturers and a major breakthrough for future frequency step-tuneable operation.

This paper presents a novel linear solar concentrating system named BDLFR, acronym of Beam-Down Linear Fresnel Reflector. A BDLFR system consists of a primary LFR array reflecting sunlight into a secondary hyperbolic –or elliptic– cylinder mirror that beams-downs reflected rays to its secondary focal line at ground level, where the receiver is placed. A model based on vector notation –and validated against SolTrace– predicts the optical behavior of BDLFR and generates layouts to avoid blockings. The edge ray approach is utilized to determine receiver aperture widths. As a function of beam-down curvature ratio, the BDLFR configurations that maximize solar collection are found out. Concentration ratios about 80 are reached with a tertiary re-concentrator (CPC) coupled to the receiver aperture.

Single-channel conductance measurements in biological pores have demonstrated the importance of interfacial effects in nanopores, particularly in protein channels with low aspect ratio (length over aperture radius). Access resistance (AR), the contribution to the total measured resistance arising from the electrodiffusive limitation that ions experience in passing from bulk solution to confinement within the pore, becomes essential in the description of ionic transport across these biological channels. Common analytical estimates of AR are based on idealized nanopore models, cylindrical in shape, electrically neutral and embedded in a neutral substrate. Here we calculate the AR of five protein channels by using their atomic structure and a mean-field approach based on solving 3D Poisson and Nernst-Planck equations. Our approach accounts for the influence of the protein charged ionizable residues, the geometry of the pore mouth and the ion concentration gradients near the pore. We compare numerical calculations with the few available AR measurements and show for several protein channels that analytical predictions tend to overestimate AR for physiological concentrations and below. We also discuss the relationship between AR and the size of the channel aperture in single-pore channels and three-pore channels and demonstrate that in the latter case, there is an enhancement of AR.

The kinetic energy of neutralized oxygen particles passing through an aperture electrode was measured by a quadrupole mass spectrometer. The peak energy position was controlled by changing the plasma source power, acceleration bias power, and gas pressure in the vacuum chamber. Keywords: Beam energy, Neutralized plasma particle, Oxygen plasma

An essential aspect of the nano-aperture ion source is the delivery of gas towards the double aperture structure. This requires a nano-fluidic channel. In order to estimate the fluidic properties and understand the underlying transport mechanisms of such a channel, a flow model was developed. The model shows good agreement with three different sets of experimental data. The model is used to show that naive channel design will perform poorly. Nevertheless, carefully designed channels that perform well are achievable.

In this chapter I discuss the bright-field microscope, perhaps, along with the telescope, one of the most elegant and important scientific instruments ever invented. I discuss some of the discoveries made with the bright-field microscope. I discuss the components of the bright-field microscope, particularly the objective lenses. I discuss the aberrations that can occur in the objective lenses and the methods used to correct them in order to obtain high-quality objectives. I discuss how to establish Kohler illumination and the optical paths taken by the illuminating rays and the image forming rays in the bright-field microscope set up for Kohler illumination. I discuss the use of the bright-field microscope and how to adjust the field and aperture diaphragms to balance resolution, contrast, and depth of field.

In this chapter the basics of focused ion beam (FIB) systems are summarized and the nano-aperture ion source (NAIS) is introduced. First a brief overview of ion-surface interactions and their applications is given. Next, the most important optical aspects of FIB systems are discussed and a comparison of different ion sources is made. After this discussion of focused ion beams in a general context, the nano-aperture ion source is introduced. A basic theoretical model from which estimates of the performance can be made is derived. In addition, an optimization for the required electron column is discussed. The basic model in combination with the electron beam optimization is used to acquire performance estimates of the NAIS.

When ions are extracted from the nano-aperture ion source, they inevitably interact with the neutral particles. In this chapter, a model for such interactions is presented. An important finding is that the current and the brightness tend to keep increasing with increasing particle density, despite increasing ion-neutral scattering. Another result is that the spread in energies in the beam can be reduced as a consequence of more ion-neutral scattering. The model developed forms a basis to be used in simulations that also consider coulomb interactions. Besides presenting a model for advanced calculation, simplified analytically expressions are introduced that can help to understand a particular configuration or to quickly estimate the performance.

The optics of ion emission from the nano-aperture ion source were studied in the limit of a rarefied gas. In this limit the ions do not interact with neutral particles or other ions and the emission optics are determined by the electric fields, the distribution of ionization location, and the thermal energy distribution of the particles. A first order lens effect and two types of aberrations are identified. One aberration is associated with the initial energy distribution of the ions and a second aberration is caused by the initial spatial spread in the direction of the optical axis. Simple equations are derived, which enable estimates of these optical effects. Good performance is in general achieved when the fields inside and outside the chip are equal and above 3 kV/mm.

The present work investigates the deformation behavior of isotactic polypropylene in uniaxial geogrid manufacture experimentally and numerically. The extruded sheet with different geometric features of circular holes was stretched at elevated temperature and then tensile properties of geogrids at room temperature were evaluated. A numerical model based on the finite element method was established to analyze the strain distribution and predict the final shapes of products. It was found that the transverse distance played important roles on temperature deformation of the rib and the fracture behavior of geogrids, while the formation of apertures and failure locations were highly dependent on the longitudinal distance. The failure location was not sensitive to the hole diameter. It was proved that good predictions of the final shapes of the geogrid products were obtained using the proposed numerical model. The numerical results show that as the transverse distance varied, temperature deformation always focused on the rib. However, both dimensions and strain distributions at the junction exhibited different features when the longitudinal distance changed. The comparison of strain distributions with different geometric features of holes was discussed. Keywords: Geogrid, Tensile behavior, Mechanical property, Finite element method, Aperture

For cell phone cameras, it is desirable to utilize electromagnetic micromotors with a thin profile and high torque to drive a variable aperture. However, thinning these down to submillimeter dimensions can severely decrease the torque. In this paper, we propose a slice motor featuring both a thin profile (about 10 mm in diameter and less than 1 mm in thickness) and a high torque (above 20 μN m). The proposed micromotor comprises an 80-pole NdFeB ring magnet and a meander micro coil. The 80-pole ring magnet (o9.6 × i7 × t0.3 mm) has a pitch of 0.3 mm and is employed as a powerful micro flux source. To minimize the self-demagnetization effect, we magnetized this by single-sided laser assisted heating. However, the magnetization achieved was insufficient due to the small temperature rise on the opposite side to where the laser irradiation was applied. To improve the magnetization, we tested double-sided laser assisted heating. As a result, the magnetization of the ring magnet was improved from 53.6% to 75.9% of the design value. The meander micro coil (line/space: 0.1/0.2 mm, thickness: 0.05 mm) was fabricated by Si wet etching and silver-paste screen printing. The micromotor was successfully rotated at speeds of 0.16–1.22 rad/s by supplying a current of 250 mA AC at frequencies from 1 to 10 Hz. To evaluate the static driving torque of the motor, which is on the micronewton-meter scale, a new measurement sensor utilizing a tiny hollow cylindrical PDMS beam is proposed. The measurement principle is based on the rotation of the PDMS torsion bar under the driving torque applied by the micromotor. The results indicate that this method is feasible for measuring torque at the micronewton-meter scale. The maximum driving torque generated by the proposed micromotor was 21 μN m at 200 mA DC. This torque exceeds that of existing micro slice motors.

MIMO, Multiple Input, Multiple Output is a form of coherent lidar that can create a larger effective pupil plane image, therefore allowing improved resolution. Both synthetic aperture lidar, SAL, and MIMO create a larger synthetic aperture pupil plane image. MIMO allows a large synthetic pupil plane image in two dimensions. We also can choose to use MIMO in one dimension, and aperture motion in a second direction, to form a larger synthetic pupil plane aperture. MIMO allows significant flexibility in creating a larger synthetic pupil plane image.

A fully coupled thermal-hydraulic-mechanical (THM) finite element model is presented for fractured geothermal reservoirs. Fractures are modelled as surface discontinuities within a three-dimensional matrix. Non-isothermal flow through the rock matrix and fractures are defined and coupled to a mechanical deformation model. A robust contact model is utilised to resolve the contact tractions between opposing fracture surfaces under THM loadings. A numerical model has been developed using the standard Galerkin method. Quadratic tetrahedral and triangular elements are used for spatial discretisation. The model has been validated against several analytical solutions, and applied to study the effects of the deformable fractures on the injection of cold water in fractured geothermal systems. Results show that the creation of flow channelling due to the thermal volumetric contraction of the rock matrix is very likely. The fluid exchanges heat with the rock matrix, which results in cooling down of the matrix, and subsequent volumetric deformation. The cooling down of the rock matrix around a fracture reduces the contact stress on the fracture surfaces, and increases the fracture aperture. Stress redistribution reduces the aperture, as the area with lower contact stress on the fracture expands. Stress redistribution reduces the likelihood of fracture propagation under pure opening mode, while the expansion of the area with lower contact stress may increase the likelihood of shear fracturing.

We demonstrate a self-aligned process to fabricate Vertical-Cavity Surface-Emitting Lasers (VCSEL) which combines, within a single lithographic step the mesa etch, the surface passivation, the opening of the emission window and the top annular metallization. This process flow, based on a double photoresist layer enabling two lift-off steps, offers great advantages such as easy and fast implementation while insuring a perfect alignment between the emitting window, the passivation layer aperture and the metal-ring contact. VCSEL fabrication is drastically simplified and its repeatability improved. Finally, this process can be advantageously applied to other photonic devices such waveguide-ridge lasers, modulators, LED, etc.

This chapter first describes the different types of rock discontinuities and then discusses how to characterize their geometrical properties, including orientation, intensity, persistence, trace length, shape, size, roughness, aperture, and fillings. Both traditional characterization methods and recent developments are presented and discussed.

The beam position monitor (BPM) is an essential component for the PEFP 100-MeV linac's commissioning. A prototype stripline-type linac BPM was designed for this purpose. The electrode aperture is 20 mm in diameter, and the electrode is 25 mm long, so it can be installed between Drift Tube Linac (DTL)101 and DTL102, which is the shortest distance. One end of the electrode is connected to the Sub Miniature Type A (SMA) feed through for signal measurement, and the other end is terminated as a short. The signal amplitude of the fundamental component was calculated and compared with that of the second harmonic component. The designed BPM was fabricated and a low-power RF test was conducted. In this paper, the design, fabrication and low power test of the BPM for the PEFP linac are presented.

A solar tracker can keep the collector’s aperture perpendicular to the incident light to maximize the solar radiation, so it is a key component to improve the performance of solar collector. In this chapter, the composition and types of solar tracking are summarized, and the applications of various technologies are demonstrated respectively.

Nanoplasmonic devices are among the most sensitive chemical sensors, with sensitivities reaching the single-molecule level. An especially convenient class of such sensors is that based on metasurfaces with subwavelength nanoholes, examples being extraordinary optical transmission arrays and double fishnet structures. Such structures ensure operation both in transmission and reflection mode and ensure high sensitivities and excellent coupling with external readout. In this paper we consider the possibility to tailor the response of aperture-based sensor structures by modifying the geometry of nanoholes at the deep subwavelength level through ensuring controlled use of nonlocal effects. We investigate the case where nonlocality is achieved by modifying the basic metamaterial fishnet structure (a metal-dielectric-metal sandwich with rectangular openings) by superposing additional subwavelength patterns, ensuring the appearance of new optical modes. The obtained unit cell superstructure will have multiple tailorable spectral peaks that will increase the selectivity at different wavelengths. The finite elements method was used for simulations of the proposed structures. As an example, we applied our results to the case of a benzene sensor, showing that its spectral properties and selectivity can be tuned by modifying geometry at a deep subwavelength scale. The obtained custom-designed spectral selectivity is convenient for multianalyte chemical sensing using a single structure.

The real space and spatial frequency representations of the electron wavefunction are presented and discussed. The effects of an aperture and of the spherical illumination are taken into account, and the strong similarity with the optical case is illustrated by the thin lens case. It is also shown how the gap between wave and particle optics can be filled using the stationary phase approximation.

[EN] In this paper, we have compared the performance of two commercial systems, Kaleo-I and IOLA Plus, in the characterization of monofocal intraocular lenses (IOLs) according to the International Standard requirements (ISO 11979-2). The dioptric power (DP) and the Modulation Transfer Function (MTF) at 100.1p/mm and 3.0 mm aperture have been measured with both instruments in twenty commercial monofocal HEMA IOLs and their agreement was assessed by Bland Altman analysis. Compared with the designed power, IOLA Plus gave lower values in 85% of measures: Kaleo I errors are dependent on the power of the lens: measurements were higher than the designed power in the low-medium power range and lower than the labelled power in the high-power range. Differences in the MTF measurements between instruments were statistically significant, with an agreement of +/- 0.12 within the 95% confidence interval. IOLA Plus was very much reliable than Kaleo I in DP measurements. On the other hand, the reliability in the MTF measurements was similar for both instruments. (C) 2016 Elsevier GmbH. All rights reserved., This study was supported by the Ministerio de Economia y Competitividad and FEDER (Grant DP12015-71256-R), and by the Generalitat Valenciana (Grant PROMETEOII-2014-072), Spain. The authors acknowledge AJL S.A. for providing the IOLA Plus instrument and the set of lenses employed in this work.

The fluid flow in rock fractures during shear processes has been an important issue in rock mechanics and is investigated in this paper using finite element method (FEM), considering evolutions of aperture and transmissivity with shear displacement histories under different normal stress and normal stiffness conditions as measured during laboratory coupled shear-flow tests. The distributions of fracture aperture and its evolution during shearing were calculated from the initial aperture, based on the laser-scanned sample surface roughness results, and shear dilations measured in the laboratory tests. Three normal loading conditions were adopted in the tests: simple normal stress and mixed normal stress and normal stiffness to reflect more realistic in situ conditions. A special algorithm for treatment of the contact areas as zero-aperture elements was used to produce more accurate flow field simulations, which is important for continued simulations of particle transport but often not properly treated in literature. The simulation results agree well with the measured hydraulic apertures and flow rate data obtained from the laboratory tests, showing that complex histories of fracture aperture and tortuous flow fields with changing normal loading conditions and increasing shear displacements. With the new algorithm for contact areas, the tortuous flow fields and channeling effects under normal stress/stiffness conditions during shearing were more realistically captured, which is not possible if traditional techniques by assuming very small aperture values for the contact areas were used. These findings have an important impact on the interpretation of the results of coupled hydro-mechanical experiments of rock fractures, and on more realistic simulations of particle transport processes in fractured rocks.

In a high-pressure photoelectron spectrometer, the sample is positioned close to a differential pumping aperture, behind which the pressure is several orders of magnitude lower than the pressure in the analysis chamber. To find the optimal sample position, where the path length of the photoelectrons through the high pressure region is minimized as far as possible without compromising knowledge of the actual pressure at the sample surface, an understanding of the pressure variations near the sample and the aperture is required. A computational fluid dynamics study has been carried out to examine the pressure profiles, and the results are compared against experimental spectra whose intensities are analyzed using the Beer–Lambert law. The resultant pressure profiles are broadly similar to the one previously derived from a simplistic molecular flow model, but indicate that as the pressure in the analysis chamber is raised, the region over which the pressure drop occurs becomes progressively narrower.

This paper presents a stress-induced variable aperture model to characterise the effect of polyaxial stress conditions on the fluid flow in three-dimensional (3D) persistent fracture networks. Geomechanical modelling of the fractured rock is achieved by the finite-discrete element method (FEMDEM), which can capture deformability of matrix blocks, heterogeneity of stress fields as well as sliding and opening of pre-existing fractures. Propagation of new cracks is not required for this study of persistent fracture systems. The deformed fracture network topologies include details of dilation, opening and closing of fracture apertures, from which the local variations in hydraulic apertures are derived. Stress-controlled distribution of fracture apertures is modelled with both fracture-scale and network-scale effects considered. Under a geomechanical condition with low differential stress ratio, fracture porosity is dominated by the fracture-scale roughness. However, with the increase of stress ratio, some favourably oriented fractures are reactivated for shearing, and matrix blocks are promoted to rotate and generate large openings along their boundaries, which tend to be the key contributors to the aperture field in such persistent systems. The flow behaviour is then considered for these stressed but static solid skeletons and is investigated using a finite element solution to the Laplace problem of single-phase fluid flow. The equivalent permeability tensor of each cube-shaped rock mass is computed based on a series of flow simulations under a macroscopic pressure differential applied at opposite model boundaries with no-flow conditions on the remaining boundaries. Components of the permeability tensor are found to vary more than three orders of magnitude with respect to the change of stress ratio. Large aperture channels formed under a critical stress state accommodate significant localisation features in the flow structure of the network. The results of this study have important implications for upscaling permeability to grid block properties for reservoir flow simulation.

We manipulate and guide light to gather irradiance from a large aperture area into a smaller receiver area, called concentration. Concentration can be used for all three solar conversion processes: optoelectronic, optocaloric, and photoelectrochemical methods. The most common practical metric for concentration is the geometric ratio. The optical concentration ratio is the measure of the average irradiance impinging upon the area of the receiver relative to the irradiance collected by the larger aperture. There are two main physical methodologies to concentration: imaging and non-imaging concentration. Two macroscopic material properties can be employed for concentration: refraction (lenses) and reflectance (mirrors). Concentrating solar power focuses light for applications in electrical power generation, industrial process heating, driving mechanical steam pumps, as well as solar cooking. Finally concentration has the potential to reduce costs of a total system by replacing highly expensive receiver/absorber materials with less expensive reflecting surfaces.