Aperture Dimensions Research Articles

A new fractal approach for describing induced-fracture porosity/permeability/ compressibility in stimulated unconventional reservoirs

The stimulated reservoir volume (SRV) with complex induced-fracture governs dominant flow rates in unconventional reservoirs. The induced-fracture spacing and aperture greatly affect the fracture properties. In this study, a new method to calculate tortuosity index of fractal induced-fracture is proposed, and the fractal dimension of induced-fracture aperture (dfa) is presented to describe the distribution of fractal induced-fracture aperture (FFAD). Combined with fractal induced-fracture spacing (FFSD) and FFAD, the fractal fracture porosity/permeability/compressibility models are given. The FFSD and FFAD influenced by fractal dimensions and their influences on fracture properties are analyzed. The results show that the dfs has a wider range than that of natural fractures, and it may be larger than 2 in 2D system in some special reservoirs, e.g. re-stimulated reservoirs. As the distance from the reference point increases, the tortuosity index gradually decreases. The larger the fractal dimension (dfs or dfa) is, the larger the fracture porosity/compressibility will be. In the cases of dfs<2 (or dfa<2), the fracture porosity/compressibility of the uniformly induced-fracture is smaller than the fractal induced-fracture near the reference point, and larger than that far away from the reference point. While in the cases of dfs>2 (or dfa>2), the fracture porosity/compressibility of the uniformly induced-fracture is larger than the fractal induced-fracture near the reference point, and smaller than that far away from the reference point. When dfs >2, the fracture permeability increases first and then decreases as the distance from the reference point increases. In other cases, the fracture permeability decreases as the distance from the reference point increases. The permeability influenced by distribution of induced-fracture aperture is greater than that influenced by induced-fracture spacing.

Optimizing High-Power Ultra-Wideband Combined Antennas for Maximum Radiation Within Finite Aperture Area

In this paper, the combined antenna array is developed to maximize the effective potential gain (Gep) within finite aperture area for the high-power ultra-wideband (UWB) radiation. The idea is to make the antenna element as small as possible, so that more elements can be arranged within the prescribed aperture area to maximize Gep of the UWB system. On the other hand, the antenna element should match the pulse excitation. This means that in the frequency domain, the working band of the antenna element should cover the spectrum of the radiated pulse, and in the time domain, critical parameters of the radiated field (e.g., rise time of the monopolar pulse) should not be distorted, and those can be the principles for the UWB antenna to match the pulsed excitation, based on which the minimum size of the antenna element can be determined. With this method, a four-element combined antenna array is designed. Also, an impedance transformer and power divider are designed to feed the antenna array. Also, a big combined antenna is developed with the same aperture dimensions (30 cm × 30 cm) as the antenna array. Then, the performances of the antenna array and the big antenna are measured and compared. Compared with the big antenna, G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ep</sub> of the antenna array is 21% higher under the applied excitation, which indicates that the proposed method can significantly improve G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ep</sub> of the UWB system within the prescribed aperture area. Finally, the antenna array is furthermore optimized by adjusting the distances between the elements, and Gep is improved by another 11%, the total improvement is 33%, and the corresponding effective potential gain is 1.49.

A Wideband, Single-Layer Reflectarray Exploiting a Polarization Rotating Unit Cell

We present a new technique for designing wideband, single-layer reflectarray antennas. The proposed reflectarray exploits a wideband, polarization rotating unit cell that rotates the polarization of the reflected wave with respect to that of the incident wave by 90°. This unit cell and its mirror image were used as 1 bit spatial phase shifters capable of providing a 0°/180° phase shift over a wide bandwidth of 5.4–12.7 GHz. Using this, a reflectarray antenna with 1 bit phase quantization was designed to operate at ${X}$ -band with aperture dimensions of $28.8\,\,\text {cm}\times 28.8$ cm and a focal length of 30 cm. A prototype of the proposed reflectarray was fabricated and characterized using a spherical near-field measurement system. We determined the antenna’s 3 dB gain bandwidth to be approximately 37.4% with a maximum realized gain of 24.2 dBi. Over its entire band of operation, the polarization purity of the antenna remains better than 13 dB and sidelobe levels of better than 12 dB were achieved.

The Analytical and Artificial Intelligence Methods to Investigate the Effects of Aperture Dimension Ratio on Electrical Shielding Effectiveness

This paper presents that the effect of single aperture size of metallic enclosure on electrical shielding effectiveness (ESE) at 0 – 1 GHz frequency range has been investigated by using both Robinson’s analytical formulation and artificial neural networks (ANN) methods that are multilayer perceptron (MLP) networks and a radial basis function neural network (RBFNN). All results including measurement have been compared each other in terms of aperture geometry of metallic enclosure. The geometry of single aperture varies from square to rectangular shape while the open area of aperture is fixed. It has been observed that network structure of MLP 3-40-1 in modeling with ANN modeled with fewer neurons in the sense of overlapping of faults and data and modeled accordingly. In contrast, the RBFNN 3-150-1 is the other detection that the network structure is modeled with more neurons and more. It can be seen from the same network-structured MLP and RBFNN that the MLP modeled better. In this paper, the impact of dimension of rectangular aperture on shielding performance by using RBFNN and MLP network model with ANN has been studied, as a novelty.

Morphometric Analysis of the Orbital Aperture in North Indian Population: A Retrospective Digital Forensic Study.

Introduction:The morphometric variations seen in the orbital aperture play a significant role in forensic anthropology, for determining the personal and gender identification, especially in case of mass disasters.Aim:The aim of the present study was to evaluate the orbital aperture dimensions along with interorbital distance as observed on posteroanterior (PA) cephalograms for personal and gender identification.Materials and Methods:The present retrospective study was conducted to evaluate the morphometric dimensions of orbital aperture seen on PA cephalogram taken using PLANMECA digital machine and ROMEXIS software. The height and width of the orbits along with the interorbital distance were measured using measuring tools in the accompanying software. Data were analyzed using SPSS software version 21.0.Results:All the linear measurements such as orbital height, orbital width, and interorbital distance were significantly greater in males than females in the North Indian population with P = 0.001. The present study found 84.8% accuracy after subjecting the obtained value to discriminant function analysis.Conclusion:The morphometric analysis of the orbital aperture using postero-anterior cephalogram can be used as an adjuvant for personal and gender identification in forensic anthropology.

Blue-blocking Filters and Digital Eyestrain.

Many manufacturers are currently marketing blue-blocking (BB) filters, which they claim will reduce the symptoms of digital eyestrain (DES). However, there is limited evidence to support the proposal that DES results from the blue light emitted by these devices. The visual and ocular symptoms commonly experienced when viewing digital screens are collectively termed DES. The emission spectrum of modern digital displays frequently includes a high percentage of blue light. Being higher in energy, these short wavelengths may contribute to DES. This study examined the effect of a BB filter on symptoms of DES during a sustained near-vision task. Twenty-three young, visually normal subjects were required to perform a 30-minute reading task from a tablet computer. The digital screen was overlaid with either a BB or neutral-density (ND) filter producing equal screen luminance. During each session, the accommodative response, pupil diameter, and vertical palpebral aperture dimension were measured at 0, 9, 19, and 29 minutes after the start of the reading task. Immediately following each session, subjects completed a questionnaire to quantify symptoms of DES. The BB filter blocked 99% of the wavelengths between 400 and 500 nm. The mean total symptom scores (±1 SEM) for the BB and ND filter conditions were 42.83 (3.58) and 42.61 (3.17), respectively (P = .62). No significant differences in accommodation or vertical palpebral aperture dimension were observed between the two filter conditions, although the magnitude of the mean accommodative response did increase significantly during the first 9 minutes of the task (P = .02). A filter that eliminated 99% of the emitted blue light was no more effective at reducing symptoms of DES than an equiluminant ND filter. There is little evidence at this time to support the use of BB filters to minimize near work-induced asthenopia.

Comparison of Shielding Effectiveness in Complex Curved Structure with Different Numerical Methods, FDTD, MOM and Equivalent Circuit

&lt;p&gt;The study of the effect of shielding on high frequency equipment is very important in the electromagnetic compatibility of control and communication equipment. In this paper, while presenting a curved complex structure for the shielding enclosure, the different number of apertures with different dimensions has been investigated. A rectangular structure with two curved parts behind of the enclosure simulated based on numerical methods, FDTD, MOM and equivalent circuit for better analysis of electromagnetic interference. After introducing the proposed structure and presenting the curvature theory, simulation results are displayed and compared in the selected frequency range for three numerical methods. It has been shown that increasing the number of apertures by reducing the size, increases the effectiveness of the protective shield. However, increasing the number of resonances by increasing the apertures indicates the importance of studying the equipment more precisely before choosing the structure of enclosure. We present a complex structure for the enclosure and the different number and dimensions of apertures with different materials were investigated for analyzing the effect of shielding on electromagnetic interference. The necessity of choosing a more effective enclosure according to the frequency of the equipment is specified. Finally, three methods of numerical solution, FDTD, MOM and circuit equal comparition were performed with measured value. Changes in the Shielding effectiveness and the number of resonant in the frequency range were determined. The exact examination of equipment requires shielding and their frequency and the type of inside-to-outside communication device before choosing shieldin is important. We used a comparison of three numerical solution methods for examining the field distribution in a complex structure enclosure with different apertures and different materials. In the majority of cases, the proximity of the measured values in this frequency range with the MOM curves shows the performance of this method in complex structures.&lt;em&gt;&lt;/em&gt;&lt;/p&gt;

Comparison of step and flow-focusing emulsification methods for water-in-oil monodisperse drops in microfluidic chips

Emulsions are widely used in various disciplines such as food, chemistry, and pharmaceuticals, due to their efficient encapsulation properties. Recently, the emulsion was emerged as a unique tool for fabrication of multi-complex microparticles, which used as drug delivery agents, as effective manipulators for sorting proteins, DNA, and etc. The high productivity of stable monodisperse emulsions formation is of great importance for these aims. Here, the step and the flow-focusing methods for water-in-oil drops formation in microfluidic chips were compared as a tool for generating well-defined and monodispersed drops using mineral oil as a continuous phase. As a result, drops diameter compares with aperture (nozzle) dimensions for the flow-focusing generator and their diameter is much higher for the step design. Monodispersion and productivity for the step-chip strongly depend on phase densities difference. Flow-focusing method is more suitable for fabrication of monodispersed microparticles and step method for rough technologies such as investigating in food industry or cosmetics.

Polarization-controlled and single-transverse-mode vertical-cavity surface-emitting lasers with eye-shaped oxide aperture

We presented a single-transverse-mode and single-polarization vertical-cavity surface-emitting laser (VCSEL) with an eye-shaped oxide aperture, obtained by enhanced anisotropic oxidation of oxide layer. For apertures with dimensions of 2 × 4.6 and 3 × 6 µm2, the orthogonal polarization suppression ratio (OPSR) of the VCSEL was 22 and 19 dB, respectively. A single-mode suppression ratio (SMSR) of more than 25 dB at an output power of 0.5 mW was also achieved for the VCSEL with aperture dimension of 2 × 4.6 µm2. We believe that the proposed method to realize the mode and polarization control of VCSELs has great potential in future applications.

Trianglamine-Based Supramolecular Organic Framework with Permanent Intrinsic Porosity and Tunable Selectivity.

Here we introduce for the first time a metal-free trianglamine-based supramolecular organic framework, T-SOF-1, with permanent intrinsic porosity and high affinity to CO2. The capability of tuning the pore aperture dimensions is also demonstrated by molecular guest encapsulation to afford excellent CO2/CH4 separation for natural gas upgrading.

Degradation of Shielding Performance of Metallic Sheet due to Aperture Configuration and Dimension at 2.4 GHz

The increasing demand on wireless connectivity has opened new and modern communication systems. Many wireless systems, for example Wireless Fidelity (Wi-Fi), Bluetooth, ZigBee, share the unlicensed frequency region around 2.4 GHz. Due to intensive application of Wi-Fi systems, there are certain disturbance potentials observed. The Wi-Fi signals cause interference to ZigBee networks which are used for smart grid applications. In this work, the shielding effectiveness of a metallic enclosure with several apertures is studied. Based on analytical expression from the literature, the shielding effectiveness by varying the sheet thickness, number of apertures, and aperture patterns is calculated. Several measurements of Received Signal Strength Indicator (RSSI) are carried out. The measurements are conducted on a shielded room to isolate the measurement from other unknown signal sources. The calculation and measurement of shielding effectiveness confirmed that more apertures on a shielding sheet will reduce the Shielding Effectiveness (SE). SE for one aperture for the case sheet thickness 0.7 mm and diameter of 12 mm reduce from 46.28 dB to 14.24 dB for 6 apertures. Bigger aperture diameters will also degrade the SE from 46.28 dB to 5.27 dB for aperture diameter 24 mm. The same condition can be concluded for the thickness 1.4 mm for aperture diameter of 12 mm. However a slightly different measurement results are obtained for the thickness 1.4 mm and aperture diameter of 24 mm. The thickness plays a significant role to attenuate the wave, so that SE is bigger than the calculated one.

Sex discrimination from orbital aperture dimensions using computed tomography: Sample of Egyptian population

Abstract The present study was designed to measure and compare various measurements of orbital apertures between male and female subjects using digital computed tomography. Also to assess the usefulness of orbital aperture measures as an aid in sex determination in sample of Egyptian population. The study included 92 subjects (44 males and 48 females) with age ranged from 18 to 65 years. The results showed that males exhibited greater mean values for all the measurements except for left orbital width that was slightly increased in females. There were significant differences (p

On Alternative Approaches to Design of Corporate Feeds for Low-Sidelobe Microstrip Linear Arrays

Two design approaches, illustrated by simulations and measurements, aiming at a systematic computer-aided design of printed circuit feeds for low-sidelobe microstrip antenna arrays are described. The novelty of these approaches resides in identification of the optimal feed architectures with subsequent simulation-based optimization of the feed and array aperture dimensions. In this communication, we consider microstrip corporate feeds (CFs) realizing nonuniform amplitude excitation of linear arrays of microstrip patch antennas. Two types of the microstrip CFs are considered: with equal power split junctions and with unequal power split junctions. For each feed type, we identify candidate prototypes of feed architectures using numerical optimization of the corresponding fast feed models. Subsequently, the architectures are implemented as microstrip subcircuits within the antenna array electromagnetic (EM) models. For the sake of comparison, the antenna array circuits are defined with the same linear array of microstrip patch antennas featuring the half-wavelength element spacing, and implemented on the same microstrip substrates. Finally, the EM models are tuned—using simulation-based optimization techniques—to ensure an appropriate input reflection coefficient and minimum sidelobe levels. Selected optimal designs of antenna array circuits with 12 microstrip patches and different feeds are manufactured and measured.

Hornwort stomata do not respond actively to exogenous and environmental cues.

Because stomata in bryophytes occur on sporangia, they are subject to different developmental and evolutionary constraints from those on leaves of tracheophytes. No conclusive experimental evidence exists on the responses of hornwort stomata to exogenous stimulation. Responses of hornwort stomata to abscisic acid (ABA), desiccation, darkness and plasmolysis were compared with those in tracheophyte leaves. Potassium ion concentrations in the guard cells and adjacent cells were analysed by X-ray microanalysis, and the ontogeny of the sporophytic intercellular spaces was compared with those of tracheophytes by cryo-scanning electron microscopy. The apertures in hornwort stomata open early in development and thereafter remain open. In hornworts, the experimental treatments, based on measurements of >9000 stomata, produced only a slight reduction in aperture dimensions after desiccation and plasmolysis, and no changes following ABA treatments and darkness. In tracheophytes, all these treatments resulted in complete stomatal closure. Potassium concentrations are similar in hornwort guard cells and epidermal cells under all treatments at all times. The small changes in hornwort stomatal dimensions in response to desiccation and plasmolysis are probably mechanical and/or stress responses of all the epidermal and spongy chlorophyllose cells, affecting the guard cells. In contrast to their nascent gas-filled counterparts across tracheophytes, sporophytic intercellular spaces in hornworts are initially liquid filled. Our experiments demonstrate a lack of physiological regulation of opening and closing of stomata in hornworts compared with tracheophytes, and support accumulating developmental and structural evidence that stomata in hornworts are primarily involved in sporophyte desiccation and spore discharge rather than the regulation of photosynthesis-related gaseous exchange. Our results run counter to the notion of the early acquisition of active control of stomatal movements in bryophytes as proposed from previous experiments on mosses.

A Model for Gas Transport in Dual-Porosity Shale Rocks with Fractal Structures

A model for shale gas flow in a fractal dual-porosity rock is built and well validated with experimental data. Results indicate that (1) the gas transport in shale natural fractures gradually becomes a higher priority in the dual-porosity rock with the increase of fracture porosity; (2) the ratio of minimum fracture aperture to a fracture aperture and the fractal dimension of fracture together contribute to the fracture aperture distribution. More fractures with larger aperture exist in shale rock with larger minimum fracture aperture, which benefits gas apparent permeability; (3) a natural fracture-dominant region enlarges with decreasing fractal dimension of fracture aperture and increasing minimum fracture aperture, and this is beneficial to the improvement of the gas apparent permeability.

Theoretical characterization of annular array as a volumetric optoacoustic ultrasound handheld probe.

Optoacoustic ultrasound (OPUS) is a promising hybridized technique for simultaneous acquisition of functional and morphological data. The optical specificity of optoacoustic leverages the diagnostic aptitude of ultrasonography beyond anatomy. However, this integration has been rarely practiced for volumetric imaging. The challenge lies in the effective imaging probes that preserve the functionality of both modalities. The potentials of a sparse annular array for volumetric OPUS imaging are theoretically investigated. In order to evaluate and optimize the performance characteristics of the probe, series of analysis in the framework of system model matrix was carried out. The two criteria of voxel crosstalk and eigenanalysis have been employed to unveil information about the spatial sensitivity, aliasing, and number of definable spatial frequency components. Based on these benchmarks, the optimal parameters for volumetric handheld probe are determined. In particular, the number, size, and the arrangement of the elements and overall aperture dimension were investigated. The result of the numerical simulation suggests that the segmented-annular array of 128 negatively focused elements with 1λ × 20λ size, operating at 5-MHz central frequency showcases a good agreement with the physical requirement of both imaging systems. We hypothesize that these features enable a high-throughput volumetric passive/active ultrasonic imaging system with great potential for clinical applications.

Microwave Soil Treatment Improves Weed Management in Australian Dryland Wheat

Abstract. Herbicide resistance has prompted the development of a chemical-free weed management practice in no-till farming systems. In this study, we examined the effect of pre-emergence microwave (MW) soil treatment for weed management in a no-till wheat production system in Australia. One-time MW soil treatment (2.45 GHz, 600 W, 120 s) was applied to plots that were arranged in a randomized complete block design with five replicates. The MW energy was projected through a horn antenna with aperture dimensions of 5.5 cm × 11 cm into the topsoil (0 to 6 cm) horizon. The applied MW energy density in the treated plots (2.6 m2), which was calculated by Simpson’s numerical surface integral approximation, was approximately 560 J cm-2. This achieved an increase in soil temperature of about 75°C to 80°C. This temperature induced a 65% to 80% reduction in weed establishment through thermal devitalization of the weed seedbank, compared to the untreated control plots. In addition, a substantial increase in wheat grain yield of 39.2% was achieved through MW energy application (7.8 t ha-1) compared to non-MW conditions (5.6 t ha-1). In summary, this non-chemical weed management strategy promises to effectively control herbicide-resistant weeds and sustain dryland wheat yields. Keywords: Microwave energy, Soil, Weed Suppression, Wheat.

The evolution of the stomatal apparatus: intercellular spaces and sporophyte water relations in bryophytes-two ignored dimensions.

Cryo-scanning electron microscopy shows that nascent intercellular spaces (ICSs) in bryophytes are liquid-filled, whereas these are gas-filled from the outset in tracheophytes except in the gametophytes of Lycopodiales. ICSs are absent in moss gametophytes and remain liquid-filled in hornwort gametophytes and in both generations in liverworts. Liquid is replaced by gas following stomatal opening in hornworts and is ubiquitous in moss sporophytes even in astomate taxa. New data on moss water relations and sporophyte weights indicate that the latter are homiohydric while X-ray microanalysis reveals an absence of potassium pumps in the stomatal apparatus. The distribution of ICSs in bryophytes is strongly indicative of very ancient multiple origins. Inherent in this scenario is either the dual or triple evolution of stomata. The absence, in mosses, of any relationship between increases in sporophyte biomass and stomata numbers and absences, suggests that CO2 entry through the stomata, possible only after fluid replacement by gas in the ICSs, makes but a minor contribution to sporophyte nutrition. Save for a single claim of active regulation of aperture dimensions in mosses, all other functional and structural data point to the sporophyte desiccation, leading to spore discharge, as the primeval role of the stomatal apparatus.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'.

Experiments on, and discrete and continuum simulations of, the discharge of granular media from silos with a lateral orifice

We compare laboratory experiments, contact dynamics simulations and continuum Navier–Stokes simulations with a $\unicode[STIX]{x1D707}(I)$ visco-plastic rheology, of the discharge of granular media from a silo with a lateral orifice. We consider a rectangular silo with an orifice of height $D$ which spans the silo width $W$, and we observe two regimes. For small enough aperture aspect ratio ${\mathcal{A}}=D/W$, the Hagen–Beverloo relation is obtained. For thin enough silos, ${\mathcal{A}}\gg {\mathcal{A}}_{c}$, we observe a second regime where the outlet velocity varies with $\sqrt{W}$. This new regime is also obtained in the continuum simulations when the friction on side walls is taken into account in a thickness-averaged version of $\unicode[STIX]{x1D707}(I)$ $+$ Navier–Stokes (in the spirit of Hele-Shaw flows). Moreover most of the internal details of the flow field observed experimentally are reproduced when considering this lateral friction. These two regimes are recovered experimentally for a cylindrical silo with a lateral rectangular orifice of height $D$ and arc length $W$. The dependency of the flow rate on the particle diameter is found to be reasonably described experimentally using two geometrical functions that depend respectively on the number of beads through the two aperture dimensions. This is consistent with two-dimensional discrete simulation results: at the outlet, the volume fraction and the velocities depend on the particle diameter and this behaviour is correctly described by those geometrical functions. A similar dependency is observed in the two-dimensional continuum simulations.

Resolving images by blurring: superresolution method with a scattering mask between the observed objects and the hologram recorder

An important quest in optical imaging has been, and still is, extending the resolution of imaging systems beyond the diffraction limit. We propose a superresolution technique in which the image is first blurred by a scattering mask, and then recovered from the blurry data with improved resolution. We introduced a scattering mask into the space between the observed objects and the objective lens of a Fresnel incoherent correlation holography (FINCH) system to demonstrate the method. Optical waves, containing high spatial frequencies of the object, which are usually filtered out by the limited system aperture, were introduced into the system due to the scattering nature of the scattering mask. As a consequence, both the effective numerical aperture and the spatial bandwidth of the system were enlarged. The image resolution could therefore be improved far beyond the resolution limit dictated by the limited numerical aperture of the system. We demonstrated the technique using a modified FINCH system and the results were compared with other systems, all having the same aperture dimensions. We showed a resolution enhancement in comparison to conventional FINCH and regular imaging systems, with the same numerical apertures. The theoretical and experimental data presented here establishes the proposed method as an attractive platform for an advanced superresolution system that can resolve better than conventional imaging systems.