Simple Rectangle Research Articles

Sawtooth scanning strategy for additive manufacturing

PurposeThis study aims to improve the acceleration in the additive manufacturing (AM) process. AM tools, such as extrusion heads, jets, electric arcs, lasers and electron beams (EB), experience negligible forces. However, their speeds are limited by the positioning systems. In addition, a thin tool must travel several kilometers in tiny motions with several turns while realizing the AM part. Hence, acceleration is a more significant limiting factor than the velocity or precision for all except EB.Design/methodology/approachThe sawtooth (ST) scanning strategy presented in this paper minimizes the time by combining three motion features: zigzag scan, 45º or 135º rotation for successive layers in G00 to avoid the CNC interpolation, and modifying these movements along 45º or 135º into sawtooth to halve the turns.FindingsSawtooth effectiveness is tested using an in-house developed Sand AM (SaAM) apparatus based on the laser–powder bed fusion AM technique. For a simple rectangle layer, the sawtooth achieved a path length reduction of 0.19%–1.49% and reduced the overall time by 3.508–4.889 times, proving that sawtooth uses increased acceleration more effectively than the other three scans. The complex layer study reduced calculated time by 69.80%–139.96% and manufacturing time by 47.35%–86.85%. Sawtooth samples also exhibited less dimensional variation (0.88%) than zigzag 45° (12.94%) along the build direction.Research limitations/implicationsSawtooth is limited to flying optics AM process.Originality/valueDevelopment of scanning strategy for flying optics AM process to reduce the warpage by improving the acceleration.

SEMICIRCULAR SLOT BASED UWB MICROSTRIP PATCH ANTENNA FOR VARIABLE BAND NOTCHED APPLICATIONS

The patch antenna with Ultra-Wide Band (UWB) characteristics is a promising candidate for wireless communication. It is a major research problem to mitigate electromagnetic interference (EMI) with narrowband technologies such as 5G lower band, Wi-MAX, WLAN and satellite band, which are all in the UWB region. This study describes a UWB antenna with variable band rejection that can be used to avoid interference with Wi-MAX and 5G lower band applications. The UWB characteristics of a simple rectangle patch antenna with a faulty ground structure has been designed for operational bandwidth (2.7–13) GHz. A novel method semicircular slot (SCS) at the radiation patch creates a band notched from (3.25–3.80) GHz and (3.4–4) GHz. Variable band rejection between (2.95–4.40) GHz can be achieved by adjusting the “Wa” values. When measured over the band rejection frequency, the return loss (S11) and VSWR values are very close to 0 dB and larger than 2. The simulated and measured results such as return loss, VSWR, 2-D polar pattern and gain have almost similar agreement. The design of the suggested antenna is simple, compact and efficient for Wi-MAX application, this is an ideal UWB antenna with the band notch characteristics.

Millimeter‐wave frequency reconfigurable antenna using simple VO 2 ‐based paired metasurface

In this article, a millimeter-wave frequency-reconfigurable metasurface antenna by electrically controlling vanadium dioxide (VO2) is proposed and studied. As a phase change material, VO2 is an insulator at room temperature but can turn into high conductivity metallic state when activated by continuous direct current (DC) voltage. By integrating the VO2 film between two simple rectangle metasurface cells, a frequency-reconfigurable paired metasurface structure (FRPMS) is achieved. The FRPMS can be considered as one unit when VO2 film is activated to metallic state while as two independent cells when VO2 film is in insulating state. In this way, the FRPMS can operate, respectively at 28 and 38 GHz with independent tunability. Moreover, a coplanar and staggered DC bias circuit with little effect on radiation is designed to switch the operating modes of VO2 easily. The antenna is fed by a stepped waveguide with ridges through a loop slot, which is suitable for dual-band feeding with large frequency ratio. One prototype is fabricated and measured for demonstration. When the VO2 film is in metallic state, the measured working band covers from 28.5 to 29.6 GHz with the maximum gain of about 7.1 dBi. When cooled down to insulating state, the antenna can work in a higher band from 36.7 to 38.3 GHz with the maximum gain of about 7.9 dBi. Due to the advantages of simple structure, high gain and easy tuning, the antenna can be expected to use in mmW wireless communication.

Design of a Miniaturized Printed Antenna for 2.4 GHz IoT Applications

This article presents a miniaturized simple rectangle monopole antenna for Internet of Things (IoT) applications. The miniaturization is achieved by engraving three pairs of parallel slits on the antenna radiating patch. It resonates at the Industrial Scientific and Medical band (2.4 GHz) with an acceptable gain and almost perfect matching. The obtained -10 dB bandwidth of the designed antenna is 361 MHz. The proposed antenna has six slits located alternatively at the right and left sides of the radiating patch. The reflection coefficient of the proposed antenna is -34.89 dB for the simulated results and -27.23 dB for the measured results. The simulated and measured gains are 1.2dBi and 1.142 dBi, respectively, at the resonant frequency, which is so good under the condition of the antenna compact size. The proposed antenna has a simple design with low cost and very compact size, and this makes it preferable for IoT applications. Moreover, the proposed antenna has an omnidirectional radiation pattern suitable for direction-independent applications. The measured and simulated results show close agreement to each other.

Calligraphic Design in Fractal Model Based on Rectangle Collage Decomposition

A fractal model can deliver the beauty of self-similarity feature to be used in designing artistic things such as calligraphic characters. The fractal model can deliver the power of mathematics to be used in modeling the complex things that can be handled by computer programs. This paper delivers the short-cut way to design the artistic calligraphic characters based on the modification of the existing form of the simple rectangle fractal object to construct the stroke form of the calligraphic character as the simple solution of the inverse problem. The upright collage component design of rectangle fractal object can be decomposed into many cells of collage component of a calligraphic character with equal size in the right position of the cells according to the stroke of calligraphic character designed. The short-cut way to encode the fractal object is by copy-editing the representative IFS code based on the position of the cells according to the position of each component of the stroke. The calligraphic characters in fractal form as the collection of IFS code set are the representation of the affine coefficient functions, so they can be easily modified by means of the affine transformation function to any desired form.

Modeling surge pressures during tripping operations in eccentric annuli

The aim of this paper is to present a new numerical model to study the drilling fluid flow through eccentric annulus during tripping operations and to investigate the effect of the eccentricity on the annular velocity and apparent viscosity profiles. Many published works studied surge and swab phenomenon using simplified numerical models that do not consider the azimuthal variation of the shear stress in the eccentric annuli. In this paper, the developed numerical model takes into consideration this variation. Non-orthogonal, curvilinear coordinates were used to generate a body-fitted elliptic mesh that maps the irregular complicated eccentric annulus into a simple rectangle where flow equations can be discretized using the finite difference method then solved numerically. Besides, a commercial software (ANSYS Fluent 19R3) was used to support the findings of the numerical model. Results of these models were validated against the experimental data from literature where good agreement was observed with an average relative error of 2.6%, 3.8%, and 6.8% for the three Herschel-Bulkley fluids studied in the eccentric case. The profiles of velocity and viscosity were plotted, the contours showed that we cannot use an average velocity or a single value for the apparent viscosity to describe the drilling fluid flowing through an eccentric annulus, but, the whole profile should be used, instead.The developed numerical model was used in a parametric study to investigate the effect of eccentricity on the relationship between surge pressure and the relevant drilling parameters namely tripping velocity, annular geometry, and fluid rheological properties. The results showed that the eccentricity decreases the surge pressure independently of the previous parameters and that the rate of decrease varies from one parameter to another. The outcome of this parametric study was used to construct a surrogate model using Random Forest Regressor. Predictions from the surrogate model fit the numerical data very well with R-squared of 0.99 and 0.97 for training and test data, respectively.

Analysis of aluminum front bumper beam for heavy quadricycles under impact loading

A heavy quadricycle is a small four-wheeled vehicle suitable for urban mobility owing to its compact, lightweight and energy-efficient advantages. However, such small vehicles have a comparatively short crumple zone leading to a higher risk of occupant injury in case of frontal collision. In this paper, the structural performance and energy absorption of aluminum alloy AA6063-T6 thin-walled front bumper beams for heavy quadricycles are studied. Mechanical characteristics of the beams with simple cross-sectional profiles, i.e., square, rectangle and double-cell rectangle as well as a commercially available bumper beam of a heavy quadricycle under cylindrical-rod impact loading are investigated through finite element analysis using LS-DYNA. A parametric study is also performed to examine the effects of open and closed sections, different cross-sectional shapes and various fillet radii on impact responses of the bumper beam including energy absorption, specific energy absorption, peak force, and crush force efficiency. The results show that although section profiles with sharp corners possess higher energy absorption, a larger fillet radius could mitigate the unfavourable peak force from impact up to 40%. The partition plate of the double-cell rectangle section induces a much higher peak force compared to others. In addition, when comparing an open-section beam with closed-section beams, it is found that an open-cell hat-shape model with fillet radius of 8 mm is the most efficient design. The crush force efficiency and peak force of the section are 32% higher and 17% lower, respectively, when compared to the closed-cell section with fillet radius of 8 mm.

Basic Research on Comparative Evaluation of Calculated Dose Distribution Using Monte Carlo Algorithm-equipped Treatment Planning Systems in Volumetric Modulated Arc Therapy

The purpose was to study comparative evaluation of calculated dose distribution by X-ray Voxel Monte Carlo (XVMC) for dose calculation in Acuros XB (AXB). The dose commissioning and head and neck volumetric modulated arc therapy (VMAT) clinical cases were compared for AXB in Eclipse and XVMC in Monaco. For TrueBeam at 6 MV, we compared the dose commissioning for simple rectangle, heterogeneity correction, and multileaf collimator (MLC) characteristics. 15 clinical cases were compared for computation times, calculation accuracy, dose-volume histogram (DVH), and 3D-γ analysis (γ 3%/2 mm). There was no difference between the calculated values of jaw field, the measurement errors of both were within± 1%, and the dose profiles of water, bone, and lung equivalent slab phantoms were in good agreement. There was no difference in transmission, tongue and groove effect, and there was a difference of less than 10% in leaf-end transmission. In clinical cases, the computation time of XVMC was a half time that of AXB, the average values of the dose difference between the two dose calculations were -1.17±2.14%, and there was no difference in measurement error (AXB: -0.73±0.79%, XVMC: -0.07±1.21%). In DVH, max doses of XVMC were about 3% higher in planning target volume (PTV) and gross tumor volume (GTV), but the pass rate of 3D-γ analysis was overall 95.11±2.59%, which was in good agreement. Both dose calculation algorithms were equivalent, suggesting that Monaco XVMC is a verification method with a high accuracy for comparative evaluation of calculated dose distribution.

Anisotropic metasurface with high-efficiency reflection and transmission for dual-polarization

Recently, accelerating advances in coding metasurfaces linking metamaterial and digital codes have enabled unexampled route for electromagnetic (EM) waves manipulation, including perfect reflection and transmission. In this paper, an anisotropic coding metasurface with a semi-discontinuous metallic ground sheet are proposed, which realizes dual independent functionalities by changing the polarization of incident waves. The ultrathin metasurface is composed of eight coding elements based on a simple rectangle metal patch and the reflective phases of these elements fully cover 360°. Both numerical and measured results show that our design is able to near-perfectly reflect the normally incident y-polarized wave to desired reflection angle and transmit the y-polarized plane wave with high efficiency. In addition, considering the simple structure, easy fabrication process and decent control ability on EM waves, the proposed coding metasurface may be exploited for more complex functionalities.

Модель хаотической маскировки сообщений с использованием ортогональных функций

The model for chaotic signal masking is proposed in the article. The digital signal in the bit representation is encoded using a family of orthogonal functions. Random white noise is superimposed on the resulting analog signal. The white noise amplitude is significantly greater than the amplitude of the signal. The functions orthogonal property is used to retrieve a useful signal. The advantage proposed this model is that it is not necessary to match the noise generators in the source and in the receiver of the message. The integration operation is required to retrieve the message. The using a simple rectangle scheme is discussed. The comparative computer experiment is based on two families of orthogonal functions: simple trigonometric functions and orthogonal Lagrange polynomials. It has been shown that using the trigonometric function family results in fewer errors when retrieving a message.

Fetishizing the Foot: Mobility and Meaning in Indian Ocean Sandals

Fetishizing the Foot: Mobility and Meaning in Indian Ocean Sandals

Aspect ratio of radiation-hardened MOS transistors

The reliability of electronics in the proximity of the ionizing radiation is a key requirement in particular in high energy physics, nuclear power or space applications. One way to improve robustness of MOS transistors operating in such environments is to use enclosed layout techniques. This special layout approach helps to maintain leakage current of MOS transistors at low level even after irradiation, in contrast to a linear layout MOS transistor, where leakage current could increase by orders of magnitude. The issue, arising with enclosed layout transistors, is related to channel modelling, since the MOS transistor gate geometry is no more a simple rectangle. In this work, modelling of equivalent width and length dimensions of the MOS transistor channel under the gate is addressed. For this purpose transistors of four types and two layout versions, fabricated in a standard 180 nm CMOS process, are characterized. The accuracy of available models for equivalent channel dimensions is analysed, along with a new simplified geometrical model developed by the authors. They are further compared to the empirically extracted aspect ratio. The improvement possibilities for the considered models are then identified.

Reduction in operator radiation exposure during transradial coronary procedures using a simple lead rectangle.

ObjectivesTransradial access for percutaneous coronary intervention (PCI) reduces procedural complications however, there are concerns regarding the potential for increased exposure to ionizing radiation to the primary operator. We evaluated the efficacy of a lead-attenuator in reducing radiation exposure during transradial PCI.Methods and resultsThis was a non-randomized, prospective, observational study in which 52 consecutive patients were assigned to either standard operator protection (n = 26) or the addition of the lead attenuator across their abdomen/pelvis (n = 26). In the attenuator group patients were relatively older with a higher prevalence of peripheral vascular disease (67.9 vs 58.7 p = 0.0292 and 12% vs 7.6% p < 0.001 respectively). Despite similar average fluoroscopy times (12.3 ± 9.8 min vs. 9.3 ± 5.4 min, p = 0.175) and average examination doses (111866 ± 80790 vs. 91,268 ± 47916 Gycm2, p = 0.2688), the total radiation exposure to the operator, at the thyroid level, was significantly lower when the lead-attenuator was utilized (20.2% p < 0.0001) as compared to the control group. Amongst the 26 patients assigned to the lead-attenuator, there was a significant reduction in measured radiation of 94.5% (p < 0.0001), above as compared to underneath the lead attenuator.ConclusionsAdditional protection with the use of a lead rectangle-attenuator significantly lowered radiation exposure to the primary operator, which may confer long-term benefits in reducing radiation-induced injury.Advances in knowledgeThis is the first paper to show that a simple lead attenuator almost completely reduced the scattered radiation at very close proximity to the patient and should be considered as part of the standard equipment within catheterization laboratories.

Laser-based Package Singulation and Trenching for SiP

Pulsed lasers are solving some packaging challenges for SiP applications. SiP devices designed for mobile devices with communication capability often have a need for EMI shielding. Nanosecond UV and picosecond green lasers are finding use in cutting these multi-compound packages as well as trench for exposing board contacts used for grounding. Mechanical cutting may not be an option if the perimeter of the package is not a simple rectangle. Water jet cutting may bear the risk of the package to fail to to water seeping in between the package layers during cutting. We will demonstrate how laser-based SiP package cutting and trenching can ameliorate both of those concerns and point toward limitations of laser-based processes. Today's high power nanosecond UV lasers are capable of cutting 1mm thick packages at an effective cutting speed of more than 10mm/s. The resulting cut surface shows no charring or melting. The surface roughness allows for excellent adhesion of EMI shielding paint on the cut conformal compound. Since the laser beam can be controlled with a programmable scanner, arbitrary shapes can be cut just as easily as simple rectangles. Difference ablation rates between polymer and copper allow the laser to trench the conformal coating and stop automatically when a metal layer is exposed. This self-terminating process leads to a precise exposure even when the conformal coating thickness differs from part to part. For the utmost in surface quality picosecond lasers can be employed. Their shorter pulse duration allows for an even lower surface roughness and less thermal impact on the package. Using an ultrafast laser, such as a 10ps laser, has the additional advantage that the process scales in speed with increased laser power. The excellent edge quality and possibility to cut random shapes allow laser-based processes to complement mechanical processes in high-end applications. We will present a full cost of ownership model that allows the designer to predict the exact singulation and trenching cost for a given package size.

Persistence in a Two-Dimensional Moving-Habitat Model.

Environmental changes are forcing many species to track suitable conditions or face extinction. In this study, we use a two-dimensional integrodifference equation to analyze whether a population can track a habitat that is moving due to climate change. We model habitat as a simple rectangle. Our model quickly leads to an eigenvalue problem that determines whether the population persists or declines. After surveying techniques to solve the eigenvalue problem, we highlight three findings that impact conservation efforts such as reserve design and species risk assessment. First, while other models focus on habitat length (parallel to the direction of habitat movement), we show that ignoring habitat width (perpendicular to habitat movement) can lead to overestimates of persistence. Dispersal barriers and hostile landscapes that constrain habitat width greatly decrease the population's ability to track its habitat. Second, for some long-distance dispersal kernels, increasing habitat length improves persistence without limit; for other kernels, increasing length is of limited help and has diminishing returns. Third, it is not always best to orient the long side of the habitat in the direction of climate change. Evidence suggests that the kurtosis of the dispersal kernel determines whether it is best to have a long, wide, or square habitat. In particular, populations with platykurtic dispersal benefit more from a wide habitat, while those with leptokurtic dispersal benefit more from a long habitat. We apply our model to the Rocky Mountain Apollo butterfly (Parnassius smintheus).

Reduction of undesired lateral forces acting on the flapper of a flapper–nozzle pilot valve by using an innovative flapper shape

The stability and dynamic performance of a flapper–nozzle pilot valve significantly depend on the flow forces acting on the flapper. Due to the shape of the flapper and flow structure in the flapper–nozzle pilot valve there are undesired lateral forces acting on the flapper, which are very potential to interfere with the stability of the flapper. Aiming to reduce these undesired lateral forces, an innovative flapper shape is proposed and a comparative study of flow forces acting on the two different flapper shapes is conducted. A simple rectangle shape is selected as the innovative flapper shape. The flow forces acting on the traditional flapper shape and innovative flapper shape are evaluated by means of CFD (Computational Fluid Dynamics) simulations and verified with the results from the semi-experimental approach. The evaluation of the flow forces is performed for each flapper shape with two different flapper–nozzle clearances of 0.10mm and 0.05mm under seven different flow conditions with the variation of inlet pressures from 1MPa to 7MPa. A good agreement between CFD results and semi-experimental results shows that the proposed innovative flapper shape has no effect on flow control characteristics since it is giving approximately the same flow rate and main flow force as the traditional flapper shape at every flow condition. Meanwhile the innovative flapper shape effectively reduces the undesired lateral forces acting on the flapper by altering the flow structure and reducing the strength of the jet flow and cavitation occurred in the flow field of flapper–nozzle pilot valve. At the lower part of the flapper with clearance 0.05mm, the ratio between the X-direction lateral force and main flow force of traditional flapper is around 1.24–11.14%, while it is reduced to 0.18–0.42% by the innovative flapper. Also, the ratio is reduced from 7.93–18.44% to 0.69–0.93% with clearance 0.10mm. For the Z-direction forces at the lower part, the ratio decreases from 0.20–11.77% and 7.84–17.94% (traditional flapper) to 0.92–2.65% and 1.63–4.08% (innovative flapper) with clearances 0.05mm and 0.10mm respectively.

Confirmation on the effectiveness of rectangle-shaped flapper in reducing cavitation in flapper–nozzle pilot valve

The existence of undesired flow-induced phenomenon, cavitation, in the flapper–nozzle pilot valve of two-stage servo-valves is a critical issue in practical applications. Here, taking innovation on the flapper shape is one of possible approaches to reduce cavitation in the pilot valve. By means of CFD (Computational Fluid Dynamics) simulations, it has been proved by setting a simple rectangle shape as an innovative flapper shape in our previous attempt. Therefore, in this work, the effectiveness of rectangle-shaped flapper in reducing cavitation is experimentally confirmed by comparing with traditional shape and square shape. The experimental observations of cavitation phenomena in three different flapper shapes are conducted for two different flapper–nozzle null clearances (0.2mm and 0.1mm) under four different flow conditions with the variation of inlet pressure in the range of 3–6MPa. To provide verification on experimental results and a comprehensive understanding, CFD simulations of cavitation phenomenon in each flapper shape are also performed. The results are qualitatively analyzed and compared. The results explain that the cavitation intensity in the flapper–nozzle pilot valve associates with the strength of the turbulent jets and it increases with the increment of flapper–nozzle null clearance and inlet pressure. According to the experimental observations and CFD simulated results, the curved surface of traditional flapper shape is attributed to the spread of turbulent jets and consequent massive cavitation. Compared to traditional shape, the square shape relatively reduces cavitation due to lack of curved boundary on the flapper. However, on the other hand, its shorter flat land and larger annulus are not much effective to control the spread of turbulent jet which is responsible for cavitation in annulus region. Compared to two other flapper shapes, the rectangle shape significantly suppresses the cavitation by attenuating the turbulent jets on its straight and relatively longer flat lands. Therefore, the effectiveness of rectangle shape in reducing cavitation in the flapper–nozzle pilot valve is confirmed in this work.

Hybrid Wiring of the Rhodobacter sphaeroides Reaction Center for Applications in Bio-photoelectrochemical Solar Cells

The growing demand for nonfossil fuel-based energy production has drawn attention to the utilization of natural proteins such as photosynthetic reaction center (RC) protein complexes to harvest solar energy. The current study reports on an immobilization method to bind the wild type Rhodobacter sphaeroides RC from the primary donor side onto a Au electrode using an immobilized cytochrome c (cyt c) protein via a docking mechanism. The new structure has been assembled on a Au electrode by layer-by-layer deposition of a carboxylic acid-terminated alkanethiol (HOOC (CH2)5S) self-assembled monolayer (SAM), and layers of cyt c and RC. The Au|SAM|cyt c|RC working electrode was applied in a three-probe electrochemical cell where a peak cathodic photocurrent density of 0.5 μA cm–2 was achieved. Further electrochemical study of the Au|SAM|cyt c|RC structure demonstrated ∼70% RC surface coverage. To understand the limitations in the electron transfer through the linker structure, a detailed energy study of the SAM and cyt c was performed using photochronoamperometry, ellipsometry, photoemission spectroscopy, and cyclic voltammetry (CV). Using a simple rectangle energy barrier model, it was found that the electrode work function and the large barrier of the SAM are accountable for the low conductance in the devised linker structure.

High-resolution 2D NMR spectra in inhomogeneous fields via 3D acquisition

High-resolution nuclear magnetic resonance (NMR) spectroscopy plays an important role in chemical studies. Here, a pulse sequence, based on coherence transfer module of tracking differences of precession frequencies of two spins and spin echo module, is proposed to obtain two dimension (2D) high-resolution NMR spectra via 3D acquisition under large field inhomogeneity. The proposed scheme composes of simple hard pulses and rectangle gradients. Resulting 2D spectra exhibit chemical shift differences and J coupling splittings in two orthogonal dimensions. The method developed here may offer a promising way for in situ high-resolution NMR studies on combinatorial chemistry.

室内透視モデルにおける眺めの選好とその判断要素

This thesis aims to clarify the visual perceptional circuit by using several sorts of virtual indoor space model in simple rectangle shape. And the 29 virtual interior space models (9 models in the experiment-1 and 20 models in the experiment-2) which are created on the computer were shown on 40 subjects and had the experiment to make them select "an intelligible view" in each models with changing of width and height. As a result of scrutinizing the motion situation of an intention of 8 sorts obtained in this way in all the models, the hierarchical structure of each intention became clear. That is, the mechanism that the 5 types of intentions worked as a primary element in "the preference of an intelligible view", and the others worked as a secondary element was arranged.