Plane Thickness Research Articles

AN EMPIRICAL APPROACH TO DESIGN A PIFA ANTENNA

Abstract: A parametric study is performed on a Planar Inverted F Antenna (PIFA) that operates at the frequency of 900 MHz The effect of the variation of the parameters on the bandwidth (BW) is analyzed. The study is performed using the Finite Element Method (FEM) numerical technique and the High Frequency Structural Simulator (HFSS) software.Regression analysis is applied on the data obtained from the simulation to present a mathematical model that estimates the fractional bandwidth FBW. An empirical equation that predicts the FBW of the PIFA is introduced. The equation uses the effective designparameters; substrate material thickness and ground plane dimensions as predictors. A comparison between the results calculated by the equation and the results obtained via simulation is carried out for validation purposes. The results are found to be very close except for the values corresponding to substrate thicknesses above 6mm. Moreover, a second simulator using a different numerical technique is used for further verification.A PIFA that operates at the 900 MHz frequency is fabricated. The results obtained from the physical measurement are compared with the results calculated by the empirical equation and the results obtained from the simulation. Close compatibility is observed.

A Comparison of Different Techniques for Measuring the Hindfoot Moment Arm on Weight-Bearing CT: An Inter and Intra-Observer Reliability Study

Category: Hindfoot; Ankle Introduction/Purpose: The Hindfoot Moment Arm (HMA) has been used to evaluate the hindfoot alignment with the Saltzman weightbearing XRay images (1), and was recently introduced into the field of weightbearing CT (WBCT) by Saltzman et al (2). The authors of this study have noticed that when using the Saltzman WBCT HMA technique, it is very difficult to determine the specific 'one' image in coronal plane scans with the widest tibial diaphyseal to draw the long axis of the tibia. The purpose of this study was to introduce a modified technique of measuring HMA in WBCT scans and compare the inter and intra-observer reliabilities between the modified and the Saltzman WBCT HMA techniques. Methods: WBCT scans of ten healthy limbs were loaded in CubeVue software. The foot was aligned in the correct orientation in the transverse plane based on the 2nd ray and the heel and the HMA was evaluated using the modified and Saltzman techniques. Using the modified technique, the sagittal plane thickness of one scan cut was increased to include the full width and length of the tibia and the axis of the distal tibia was identified by connecting two circles tangential to both cortices of the tibia. The weightbearing point of the calcaneus was located and the HMA was evaluated by measuring the perpendicular distance of the calcaneus weightbearing point to the axis of the distal tibia with varus a negative and valgus alignment a positive value. Intraclass correlation coefficient (ICC) model was used to assess the intra- and interobserver reliability of the two HMA techniques in SAS 9.4. Results: Both techniques had excellent intra- and interobserver reliability (Saltzman WBCT HMA intra-observer ICC=0.97, Saltzman WBCT HMA inter-observer ICC=0.94, the modified WBCT HMA intra-observer ICC=0.99, the modified WBCT HMA inter-observer ICC=0.91) (Table 1). Conclusion: The modified WBCT HMA was equivalent to the Saltzman technique in both inter and intra-observer reliabilities. The authors found that the modified technique was easier and less time consuming to perform in identifying the axis of the tibia since the modified technique uses multiple cuts to restore the full thickness of tibia, which not only reduces potential error, but also saves time during measurements. Compared with a relatively shorter tibia in one cut, the reconstructed tibia provides a longer and clearer shaft to work with, which allows both proximal and distal circles to be drawn with higher precision (Figure 1). 1. Saltzman, C. L., & El-Khoury, G. Y. (1995). The hindfoot alignment view. Foot & Ankle International, 16(9), 572-576. 2. Arena, C. B., Sripanich, Y., Leake, R., Saltzman, C. L., & Barg, A. (2021). Assessment of hindfoot alignment comparing weightbearing radiography to weightbearing computed tomography. Foot & Ankle International, 42(11), 1482-1490.

Preparation and Optimization of Modified Asphalt by Profile Control Parameters at Lamadian Oilfield

The Lamadian oilfield has entered the stage of strong water cut after natural energy development and conventional water flooding development. The use of asphalt binder for profile control can not only adjust the contradiction between layers, expand the swept volume, but also improve the oil displacement efficiency. The field test has achieved certain results. The main oil layer in the Lamadian oilfield has a strong oil layer thickness and serious vertical and plane heterogeneity. After years of water injection development and polymer injection development, most oilfields have entered a period of strong water cut. In the test, it is found that the effect of different well layers is very different, the effect is unstable, and the reason is unclear. Therefore, it is necessary to carry out research on the adaptability and parameter optimization of profile control of asphalt binder through laboratory experiments. In this paper, the asphalt binder provided on site are modified and the dispersion effect of modified asphalt binder is studied, and the concentration of suspending agent is optimized. The artificial cemented core structure and injection method are improved to solve the problem of aggregated asphalt binder on the end face during injection. The displacement profile control experiment was carried out with artificial cores, and the matching relationship between the injected particle size of the asphalt binder and the permeability was determined, and the optimal injection amount was optimized for cores with different permeabilities. The research results show that adding a KCl (potassium chloride solution) solution with a concentration of 2% as a dispersant can exert a better dispersing effect on the asphalt binder. Through the plugging rate experiments of three types of asphalt binder, the profile control effect is determined as the best when the particle size of the asphalt binder is 0.06–0.1 mm. According to the experimental results, the experimental research on the injection concentration and profile control radius of the profile control agent system was carried out. Finally, it was determined that the injection concentration of 3500 mg/L and the profile control radius of 1/3–1/2 of the well spacing were the optimal injection parameters. The field application of a profile control agent provides experimental basis.

Poster 195: Inverse Relationship of Hip Capsular Thickness on Magentic Resonance Imaging and Increased Axial Distraction Under Anesthesia: Further Characterization of Hip Laxity

Objectives:The hip joint derives its stability from several biomechanical and anatomic factors, including the ligaments of the hip capsule. Recent research has implicated the hip capsule in the pathogenesis of hip instability, which is especially important when considering the inherent violation of the hip capsule with arthroscopic procedures. The purpose of this study was to characterize the relationship between quantitative axial hip distraction and capsular thickness on magnetic resonance imaging (MRI). We hypothesized that thinner hip capsules would be associated with increased axial distraction distances at maximal traction force.Methods:A retrospective review of the senior author’s primary hip arthroscopic procedures was conducted from November 2018 to June 2021. Inclusion criteria were 1) diagnosis of FAI, 2) pre-operative MRI, 3) and intra-operative fluoroscopic imaging conducted at 0 and 100 pounds (lbs) of axial distraction. Intra-operative, fluoroscopic images were obtained at the beginning of the procedure prior to any instrumentation at 0 lbs and 100 lbs of axial traction force. Distraction distance was calculated by comparing the difference of the initial joint space to the total joint space at 100 lbs and measured using a picture archiving and communication system (PACS). Hip capsule thickness was measured on pre-operative MRI or MRA imaging. Anterior and posterior capsular thickness was measured in the axial plane, while superior and inferior capsule thickness was measured in the coronal plane. Anterior and superior measurements approximated the iliofemoral ligament, with posterior and inferior measurements approximating the ischiofemoral and pubofemoral ligaments. Three measurements were taken in each region of the hip capsule and averaged to produce an accurate estimate of hip capsule thickness in each region. Statistical analysis was conducted using multiple linear regression and independent samples t-tests with an alpha of <0.05.Results:Eighty patients were included from 121 charts reviewed, with 41 patients being excluded for lack of appropriate preoperative imaging to evaluate joint distraction or capsular thickness. Bivariable regression demonstrated increased distraction associated with female sex (B = -4.303, p <0.001). Axial distraction was also shown to be increased in relation to decreased capsular thickness in the anterior axial (B = -1.291, p < 0.001), superior coronal (B = -1.433, p <0.001), and posterior axial regions (B = -1.293, p = 0.028). Multivariable regression of the hip capsular measurements demonstrated increased axial distraction associated with decreased superior coronal capsular thickness (B = -1.402, p < 0.001). Independent samples t-tests showed females had significantly decreased hip capsular thickness in the superior coronal, anterior axial, and posterior axial regions (p = <0.05).Conclusions:Our results show several significant associations with hip capsular thickness and hip axial distraction. Patients with thinner hip capsules in the anterior axial, posterior axial, and superior coronal regions were found to have increased axial distraction distances at 100 lbs of force. These findings are in line with previous descriptions of the importance of the iliofemoral ligament and hip stability, which was approximated in this study using the anterior axial and superior coronal measurements. While female sex was observed to be associated with increased axial distraction, this may potentially be secondary to females having statistically thinner hip capsules as shown by our findings. This observation provides a more nuanced anatomic explanation for this association that has been previously reported regarding patient sex and hip laxity. Our findings further demonstrate the importance of the hip capsule as it pertains to hip joint stability, providing a quantitative method to evaluate hip capsular thickness and joint distraction. Clinically, these results are important to consider in the evaluation of hip instability and capsular insufficiency.Table 1.Multivariable regression results with axial distraction at 100 1bs of force as the independent variable

Effects of exercise habituation and aging on the intersegmental coordination of lower limbs during walking with sinusoidal speed change.

BackgroundThe time courses of the joint elevation angles of the thigh, shank, and foot in one stride during walking can be well approximated by a “plane” in a triaxial space. This intersegmental coordination (IC) of the lower limb elevation angles is referred to as the planar covariation law. We examined the effects of exercise habituation and aging on the thickness of the IC plane of the lower limbs under sinusoidal speed changing conditions.MethodsSeventeen sedentary young (SY), 16 active young (AY), and 16 active elderly (AE) adults walked on a treadmill in accordance with a sinusoidal speed changing protocol at 120, 60, and 30 s periods with an amplitude of ± 0.56 m·s−1. Motion of the lower limbs from the sagittal direction was recorded to calculate the elevation angles of the lower limbs. When the best-fit IC plane was determined, the smallest standard deviation of the IC plane was considered as the anteroposterior gait variability of the lower limbs. The coefficient of variance of the step width was also quantified to evaluate the lateral step variability (CVSW).ResultsThe standard deviation of the IC plane was significantly greater in the order of SY, AY, and AE, regardless of the sinusoidal wave periods of the changing speed. The CVSW was not significantly different among the three groups.ConclusionsExercise habituation influences anteroposterior gait variability of the lower limbs, but not lateral step variability, even in young adults. Given these, gait adaptability for sinusoidal speed changes does not always decline with aging.Trial registrationUMIN000031456 (R000035911; registered February 23, 2018).Supplementary InformationThe online version contains supplementary material available at 10.1186/s40101-022-00298-w.

DIC-based approach to predict post necking behavior for AA6061, AA7075 and their friction stir welded joints

In a tensile test, the precise measurement of the area at the necking section is crucial for predicting the post-necking true stress-strain behavior. In the conventional theoretical method, this area is linked to the engineering strain using the incompressibility criteria, which is not applicable in the post necking domain. The present work proposes a digital image correlation (DIC)-based technique with two cameras for estimating real-time area reduction at a necking section of a rectangular tensile specimen during a uniaxial tensile test. In the current study, the area at a given section is computed by measuring strain synchronously in the width and thickness planes of a tensile specimen and translating the change in lengths in both planes into a global coordinate system. The area computation of the proposed approach is successfully validated by measuring the necking area of a terminated tensile specimen (stopped before fracture) by optical microscope to an error in the range of 0.12–1.10%. Following verification, the post necking behaviors of aluminum alloys such as AA6061-T6 and AA7075-T6 are assessed. The current approach is further implemented to evaluate the area reduction and post necking behavior of similar and dissimilar friction stir welding (FSW) joints of AA6061-T6 and AA7075-T6 that possess process induced microstructural inhomogeneity. The current experimental approach effectively assessed the area reduction of a similar and dissimilar FSW joint influenced by weld inhomogeneity, which is otherwise complicated to contemplate using an analytical approach.

Individual variability in the nonlinear development of the corpus callosum during infancy and toddlerhood: a longitudinal MRI analysis.

The human brain spends several years bootstrapping itself through intrinsic and extrinsic modulation, thus gradually developing both spatial organization and functions. Based on previous studies on developmental patterns and inter-individual variability of the corpus callosum (CC), we hypothesized that inherent variations of CC shape among infants emerge, depending on the position within the CC, along the developmental timeline. Here we used longitudinal magnetic resonance imaging data from infancy to toddlerhood and investigated the area, thickness, and shape of the midsagittal plane of the CC by applying multilevel modeling. The shape characteristics were extracted using the Procrustes method. We found nonlinearity, region-dependency, and inter-individual variability, as well as intra-individual consistencies, in CC development. Overall, the growth rate is faster in the first year than in the second year, and the trajectory differs between infants; the direction of CC formation in individual infants was determined within six months and maintained to two years. The anterior and posterior subregions increase in area and thickness faster than other subregions. Moreover, we clarified that the growth rate of the middle part of the CC is faster in the second year than in the first year in some individuals. Since the division of regions exhibiting different tendencies coincides with previously reported divisions based on the diameter of axons that make up the region, our results suggest that subregion-dependent individual variability occurs due to the increase in the diameter of the axon caliber, myelination partly due to experience and axon elimination during the early developmental period.

Ultra-broadband and polarization-insensitive metasurface absorber with behavior prediction using machine learning

The solar spectrum energy absorption is very important for designing any solar absorber. The need for absorbing visible, infrared, and ultraviolet regions is increasing as most of the absorbers absorb visible regions. We propose a metasurface solar absorber based on Ge2Sb2Te5 (GST) substrate which increases the absorption in visible, infrared and ultraviolet regions. GST is a phase-changing material having two different phases amorphous (aGST) and crystalline (cGST). The absorber is also analyzed using machine learning algorithm to predict the absorption values for different wavelengths. The solar absorber is showing an ultra-broadband response covering a 0.2–1.5 µm wavelength. The absorption analysis for ultra-violet, visible, and near-infrared regions for aGST and cGST is presented. The absorption of aGST design is better compared to cGST design. Furthermore, the design is showing polarization insensitiveness. Experiments are performed to check the K-Nearest Neighbors (KNN)-Regressor model’s prediction efficiency for predicting missing/intermediate wavelengths values of absorption. Different values of K and test scenarios; C-30, C-50 are used to evaluate regressor models using adjusted R2 Score as an evaluation metric. It is detected from the experimental results that, high prediction proficiency (more than 0.9 adjusted R2 score) can be accomplished using a lower value of K in KNN-Regressor model. The design results are optimized for geometrical parameters like substrate thickness, metasurface thickness, and ground plane thickness. The proposed metasurface solar absorber is absorbing ultraviolet, visible, and near-infrared regions which will be used in solar thermal energy applications.

Electronic Bone Growth Stimulators for Augmentation of Osteogenesis in In Vitro and In Vivo Models: A Narrative Review of Electrical Stimulation Mechanisms and Device Specifications.

Since the piezoelectric quality of bone was discovered in 1957, scientists have applied exogenous electrical stimulation for the purpose of healing. Despite the efforts made over the past 60 years, electronic bone growth stimulators are not in common clinical use. Reasons for this include high cost and lack of faith in the efficacy of bone growth stimulators on behalf of clinicians. The purpose of this narrative review is to examine the preclinical body of literature supporting electrical stimulation and its effect on bone properties and elucidate gaps in clinical translation with an emphasis on device specifications and mechanisms of action. When examining these studies, trends become apparent. In vitro and small animal studies are successful in inducing osteogenesis with all electrical stimulation modalities: direct current, pulsed electromagnetic field, and capacitive coupling. However, large animal studies are largely unsuccessful with the non-invasive modalities. This may be due to issues of scale and thickness of tissue planes with varying levels of resistivity, not present in small animal models. Additionally, it is difficult to draw conclusions from studies due to the varying units of stimulation strength and stimulation protocols and incomplete device specification reporting. To better understand the disconnect between the large and small animal model, the authors recommend increasing scientific rigor for these studies and reporting a novel minimum set of parameters depending on the stimulation modality.

Assessing the performance of ultrasound imaging systems using images from relatively high-density random spherical void phantoms: A simulation study.

The development of clinically meaningful, objective, and quantitative methods for assessing the performance of ultrasound imaging systems represents a continuing area of interest. One approach has been to image phantoms with randomly distributed spherical voids. The objectives of this study were: (1) to explore the potential of using relatively high-volume fraction random spherical void (RSV) phantoms as an approach for quantitatively assessing the performance of ultrasound imaging systems; (2) to identify potential metrics that can be used to provide quantitative assessments of images obtained from relatively high-volume fraction RSV phantoms; and (3) to demonstrate changes in the quantitative metrics that can occur as image features are degraded. A series (10 each) of computer-simulated RSV phantoms with a range of RSV volume fractions (0.05, 0.15, and 0.25) were generated. To determine the number of image planes necessary to provide robust measurements, a series of consecutive planes (ranging from 1 to 150) within each type of simulated phantom were analyzed. The observed circular cross-section radii histogram distributions (representing the intersection of each plane with the local distribution of spherical voids) were compared with the theoretical histogram distribution. Simulated phantom images were produced by adding speckle and degradation of imaging system performance was modeled by averaging 1 to 9 neighboring planes to represent increasing elevation plane thicknesses. Quantification of the performance of the imaging system was determined by measuring the: (1) mean number of circular cross-sections detected per image frame; (2) mean fractional area of circular cross-sections detected per image frame; (3) agreement of observed circular cross-section radii histogram distribution with the theoretical distribution (Chi-square statistic); and (4) contrast and contrast-to-noise ratio as a function of observed circular cross-section radius. Results suggest that analyses of a sufficient number of image planes (providing over approximately 3000 total circular cross-sectional areas) provides excellent agreement between the observed and theoretical histogram distributions (mean Chi-square<0.004). For the 0.15 volume fraction series of simulated RSV phantoms, using 150 image plane analyses, phantom images show decreasing mean number of circle cross-sections detected per frame (31.5 ± 0.3, 28.4 ± 0.3, 28.2 ± 0.3, 26.3 ± 0.3, and 25.3 ± 0.3); decreasing mean fractional area of circle cross-sections per frame (0.157 ± 0.002, 0.133 ± 0.001, 0.133 ± 0.001, 0.111 ± 0.001, and 0.108 ± 0.001); and a decreasing agreement with the theoretical histogram distribution of radii (Chi-square values: 0.070 ± 0.004, 0.140 ± 0.005, 0.149 ± 0.007, 0.379 ± 0.011, and 0.518 ± 0.010) for 1, 3, 5, 7, and 9 plane averages, respectively. Contrast and contrast-to-noise measurements as a function of observed circular cross-section radius also demonstrate marked changes with simulated image degradation. Results of this simulation study suggest that analyses of images obtained from relatively high-density RSV phantoms may offer a promising approach for assessing ultrasound imaging systems. The proposed measurements appear to provide reproducible, robust, quantitative metrics that can be compared with corresponding theoretical values to provide quantifiable, objective metrics of imaging system performance.

Effect of magnetic field on dislocation morphology and precipitation behaviour in ultrafine-grained 7075 aluminium alloy

• The precipitation kinetics of alloy Ⅱ (thickness direction) is enhanced compared to that of alloy I (rolling direction). • The magnetic field plays a positive effect on precipitation kinetics in alloy I because of retarding dislocation annihilation. • The precipitation kinetics of alloy Ⅱ is suppressed by magnetic field attribute to the decline of dislocation density. • The nucleation of η′ phase is promoted at the critical temperature (140 °C) due to the increase of activation energy. • A highly efficient approach to investigate the precipitation kinetics of UFG Al alloys has been put forward. The influence of magnetic field (1 T) on dislocation morphology and precipitation behaviour of ultrafine-grained (UFG) Al 7075 alloy was investigated after ageing from 90 to 200 °C via wide angle X-ray scattering (WAXS), small angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Experimental results reveal that the improved precipitation kinetics of alloys in the thickness plane (denoted as sample II) as compared to those in the rolling plane (denoted as sample I), which arises due to a higher dislocation density (morphology of dislocation cells) of the thickness plane than that of the rolling plane (morphology of dislocations and dislocation tangles). Specifically, because of different dislocation morphologies, the magnetic field positively and negatively affects the dislocation activity in samples I and II, leading to enhanced and suppressed precipitation behaviors, respectively. Interestingly, nucleation of the η′ phase is facilitated in the UFG alloy at the critical temperature (140 °C) because it affords a faster rate of atom diffusion and a higher dislocation density as compared to those exhibited by its coarse-grained alloy. This systematic and comprehensive study provides new insights into dislocation morphology and precipitation behaviour of the UFG 7075 Al alloy, while enabling the optimization of precipitation kinetics.

Critical switching current density of magnetic tunnel junction with shape perpendicular magnetic anisotropy through the combination of spin-transfer and spin-orbit torques

Recently, magnetic tunnel junctions (MTJs) with shape perpendicular magnetic anisotropy (S-PMA) have been studied extensively because they ensure high thermal stability at junctions smaller than 20 nm. Furthermore, spin-transfer torque (STT) and spin-orbit torque (SOT) hybrid switching, which guarantees fast magnetization switching and deterministic switching, has recently been achieved in experiments. In this study, the critical switching current density of the MTJ with S-PMA through the interplay of STT and SOT was investigated using theoretical and numerical methods. As the current density inducing SOT (J_{text {SOT}}) increases, the critical switching current density inducing STT (J_{text {STT,c}}) decreases. Furthermore, for a given J_{text {SOT}}, J_{text {STT,c}} increases with increasing thickness, whereas J_{text {STT,c}} decreases as the diameter increases. Moreover, J_{text {STT,c}} in the plane of thickness and spin-orbit field-like torque (beta) was investigated for a fixed J_{text {SOT}} and diameter. Although J_{text {STT,c}} decreases with increasing beta, J_{text {STT,c}} slowly increases with increasing thickness and increasing beta. The power consumption was investigated as a function of thickness and diameter at the critical switching current density. Experimental confirmation of these results using existing experimental techniques is anticipated.

ОПЕРАТОРНИЙ МЕТОД В ЗАДАЧІ ПРО ДИФРАКЦІЮ ПЛОСКОЇ ЕЛЕКТРОМАГНІТНОЇ ХВИЛІ НА КІЛЬЦЕВІЙ ЩІЛИНІ В ПЛОЩИНІ АБО НА КІЛЬЦІ

Purpose: The problem of a plane electromagnetic wave diffraction by an annular slot in the perfectly conducting zero thickness plane is considered. As a dual problem, the problem of diffraction by a perfectly conducting zero thickness ring is also considered. The paper aims at developing the operator method for the axially symmetric structures placed in free space. Design/methodology/approach: The problem is considered in the spectral domain. The scattered field is expressed in terms of unknown Fourier amplitudes (spectral functions). The annular slot is given as a unity of two simple discontinuities, namely of a disk and a circular hole in the plane, which interact with each other. The Fourier amplitude of the scattered field is sought as a sum of two amplitudes, the Fourier amplitude of the field of currents on the disk and Fourier amplitude of the field of currents on the perfectly conducting plane with circular hole. The operator equations are written for these amplitudes, which take into account the electromagnetic coupling of the disk and the hole in the plane. The equations use the reflection operators of a single isolated disk and a single hole in the plane. They are supposed to be known and can be obtained for example by the method of moments.The reflection operators can have singularities. After transformations, the equations are obtained, which are equivalent to the Fredholm integral equations of second kind and they can be solved numerically. Findings: The operator equations relative to the Fourier amplitudes of the field scattered by the discussed structure are obtained. The far zone scattered field for an annular slot and a ring for different values of parameters are studied. Conclusions: The rigorous solution of the problem of the electromagnetic wave diffraction by an annular slot in the plane and by a circular ring is obtained. The problem is reduced to the Fredholm integral equations of second kind. The far field distribution for different parameters is studied. The developed approach is an effective instrument for a number of problems of antenna technique to be solved. Key words: circular hole; disk; annular slot; ring; operator method; diffraction

The Impact of Plane Heterogeneity on Steam Flooding Development in Heavy Oil Reservoirs

Abstract Steam flooding is proven to be an effective method to improve the development effect of heavy oil reservoirs. And steam flooding is the most common oil recovery technology for heavy oil reservoirs in China. However, because of the various reservoir physical properties, bring great challenges to successful steam flooding development. According to the previous research and development practice, we know that reservoir heterogeneity has a great influence on the development effect of water flooding. Due to the heterogeneity of reservoirs, the development of different injection-production well patterns will be affected. However, it is uncertain whether reservoir heterogeneity has an impact on steam flooding development effect. In order to clarify the above scientific issues, we take Xinjiang steam flooding oilfield as the research object to carry out relevant research. According to the reservoir distribution characteristics of Xinjiang Oilfield, three conceptual heterogeneity models representing permeability, thickness, and geometric plane heterogeneity are firstly proposed. Then, mathematic models with different plane heterogeneity of reservoir sand were built. Based on the mathematic model, initial conditions, boundary condition, and geological parameters of conceptual models, different steam flooding patterns were studied by applying numerical calculation. It is found that heterogeneity is an important geological factor affecting the development of steam flooding of heavy oil reservoir. And the results showed that cumulative oil production was different of different flood pattern at the same production condition. It can be concluded that the development effect of steam flooding of heavy reservoirs is strongly influenced by flood pattern. In order to improve development effectiveness of steam flooding of heavy oil reservoirs, flood pattern should be optimized. For each type of plane heterogeneity reservoir, a reasonable flood pattern was proposed. For plane heterogeneity of permeability, thickness, and geometry form, under the conditions of that as the producer was deployed in high permeability, thick, wide sand body and injector was deployed in low permeability, thin, narrow sand body, the recovery of steam flooding in heavy oil reservoir was better. Finally, how the three types of plane heterogeneity influence steam flooding of heavy reservoirs was discussed by adopting a sensitivity analysis method. The results show that the influence of permeability heterogeneity is the largest, thickness heterogeneity is the second, and geometric heterogeneity is the least. This conclusion can help us improve the development of this reservoir. And also, the findings of this study can help for better understanding of properly deployed well pattern and how to effective develop the heavy oil reservoirs of strong plane heterogeneity for other heavy oil reservoirs.

Fiber Strain Sensor Based on Incline Plane-Shaped Long Period Fiber Grating Induced by CO2 Laser Polishing

In this paper, we propose the CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser polishing method to prepare a novel type of incline plane-shaped long period fiber grating (IPS-LPFG) for strain measurement. This structure is achieved by periodic incline plane-shaped structures polished on single mode fiber. The incline plane-shaped structure introduced asymmetric thickness of the side plane, which enhances the strain sensitivity of the sensor effectively. Experimental results illustrate that the compact strain sensor with a length of 5 mm achieves a high strain sensitivity of 15 pm/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> at the range of 0- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$900~\mu \varepsilon $ </tex-math></inline-formula> , and the temperature sensitivity of it is 54.5 pm/°C. Moreover, the proposed strain sensor has good mechanical properties and high repeatability, which demonstrates the potential in optical fiber sensing.

The effect of tool pin size and taper angle on the thermal process and plastic material flow in friction stir welding

Friction stir welding (FSW) tool pin, as a critical component of FSW tool, plays an important role in determining the final joint properties by affecting the heat generation, plastic material flow, welding loads, and so on. However, the effects of tool pin on heat and mass transfer in FSW are not elucidated and quantitative studied. In the present study, a validated model was adopted to quantitatively analyze the effects of pin size and taper angle on the thermal process and plastic material flow in FSW. The effects of pin root diameter, pin tip diameter, and pin taper angle on heat and mass transfer in FSW were quantitatively investigated, respectively. It reveals that the torque and transverse force imposed on the pin are increased with the increase of the pin diameters (including its root diameter, its tip diameter, and its size in condition of constant taper angle), while the total tool torque varies a little for the tool pin diameter considered in this study. When the pin diameters increase, the viscosity of the materials near the pin is decreased, while the temperature as well as the flow velocity is increased. More plastic material near the tool could rotate around the tool with an increase of the pin diameter. The TMAZ boundary is enlarged with larger pin diameters in FSW. Particularly, the shear layer thickness of the same horizontal plane in the range of 1 mm < z < 5 mm is significantly enlarged with an increase of pin root diameters. However, the shear layer thickness of the same horizontal plane in the region of z < 5 mm is increased when using a larger pin tip diameter. In addition, maximum width of TMAZ boundary at the top surface of workpiece was not affected by pin diameters. The model is validated by experimental results. It could lay a solid foundation for optimizing the tool pin size and taper angle in FSW.

Skeletal width changes after mini-implant-assisted rapid maxillary expansion (MARME) in young adults.

To observe skeletal width changes after mini-implant-assisted rapid maxillary expansion (MARME) and determine the possible factors that may affect the postexpansion changes using cone-beam computed tomography (CBCT) in young adults. Thirty-one patients (mean age 22.14 ± 4.76 years) who were treated with MARME over 1 year were enrolled. Four mini-implants were inserted in the midpalatal region, and the number of activations ranged from 40 to 60 turns (0.13 per turn). CBCT was performed before MARME (T0), after activation (T1), and after 1 year of retention (T2). The mean period between T1 and T0 was 6 ± 1.9 months and between T2 and T1 was 13 ± 2.18 months. A paired t-test was performed to compare T0, T1, and T2. The correlations between the postexpansion changes and possible contributing factors were analyzed by Pearson correlation analysis. The widths increased significantly after T1. After T2, the palatal suture width decreased from 2.50 mm to 0.75 mm. From T1 to T2, decreases recorded among skeletal variables varied from 0.13 mm to 0.41 mm. This decrease accounted for 5.75% of the total expansion (2.26 mm) in nasal width (N-N) and 19.75% at the lateral pterygoid plate. A significant correlation was found between postexpansion change and palatal cortical bone thickness and inclination of the palatal plane (ANS-PNS/SN; P < .05). Expanded skeletal width was generally stable after MARME. However, some amount of relapse occurred over time. Patients with thicker cortical bone of the palate and/or flatter palatal planes seemed to demonstrate better stability.

Analysis of Terahertz Wave on Increasing Radar Cross Section of 3D Conductive Model

Enhancing the frequency band of the electromagnetic wave is regarded as an efficient way to solve the communication blackout problem. In this paper, frequency of incident wave is raised to Terahertz (THz) band and the radar cross section (RCS) of the three-dimensional conductive model is calculated and simulated based on the Runge–Kutta Exponential Time Differencing–Finite Difference Time Domain method (RKETD-FDTD). Interaction of THz wave and magnetized plasma sheath is discussed. Attenuations in incident wave frequencies of 0.34 THz and 3 GHz and different plasma densities are analyzed. The monostatic RCS is used to compare the penetration in different incident wave frequencies while the bistatic RCS is fixed on 0.34 THz to study its characteristics. The simulation result has almost the same RCS as that of the model without coating plasma when the frequency of incident wave reaches 0.34 THz. The advantages of THz wave at 0.34 THz on increasing RCS and reducing the attenuation are demonstrated from different aspects including polarizations, incident angles, magnetization and anisotropy of plasma, thickness of plasma, scan planes and inhomogeneous distribution of plasma. It can be concluded that 0.34 THz has unique advantages in increasing the radar cross section and can be applied to solve the problem of communication interruption.

The effect of vaginal delivery and Caesarean section on the anal Sphincter complex of Primipara based on optimized three-dimensional ultrasound image and nuclear regression Reconstruction Algorithm.

Objective:The study used the optimized nuclear regression reconstruction algorithm to explore the value of three-dimensional perineal ultrasound evaluation of the effect of caesarean delivery and caesarean section on the anal sphincter complex of primipara.Methods:This study performed three-dimensional perineal ultrasound scanning of the anal sphincter complex of 157 primiparas 42 days after delivery. Among them, 77 were in caesarean delivery (spontaneous delivery group) and 80 were in caesarean section (caesarean delivery group) from September 2018 to December 2020 in our hospital. The thickness of the end plane, the middle plane, the distal plane and the distal plane of the external anal sphincter at 3, 6, 9, 12 o’clock direction, and measure the thickness of the central plane of the pubic rectum muscle at 4, 8 o’clock direction. At the same time, the study used tomography and volume contrast imaging to observe the morphology and integrity of the anal sphincter complex.Results:The thickness of the distal anal sphincter at the 12 o’clock direction, the proximal anal sphincter at 6, 12 o’clock, and the central plane at 9 and 12 o’clock in the obstetric group were smaller than those in the caesarean section group (all P < 0.05). There were no significant differences in the thickness of the remaining anal internal and external anal sphincter and puborectalis muscles between the two groups in different directions (all P> 0.05). In the obstetric group, a perineal sphincter defect was found via three-dimensional perineal ultrasound.Conclusion:The delivery method has a certain influence on the shape of the anal sphincter complex. The thickness of the internal and external anal sphincter of the primiparous women in a certain direction is significantly smaller than that of caesarean section. Transperineally three-dimensional ultrasound can clearly show the morphological characteristics and integrity of the anal sphincter complex, and diagnose the defect of the anal sphincter complex.

Ultrasound image based fully-automated nuchal translucency segmentation and thickness measurement

The nuchal translucency (NT) detection and thickness measurement is a milestone in the prediction of the abnormalities in addition to chromosomal disorders in a fetus in ultrasound imagery. Nuchal translucency is an accumulation of fluids just at bottom of the foetal neck which is closely associated with chromosome abnormalities with cardiac arrest within the pregnancy period of the first trimester. At the hospital, the sonographers manually estimate the thickness of the mid-sagittal plane of nuchal translucency, which is a significant marker for prenatal screening. Such a conventional process done by a technician is quite time-consuming and requires a skilled technician. Within this methodology, an automatic NT detection method based on SIFT keypoint and GRNN is proposed in the mid-sagittal plane. This Non-invasive approach is crucial not just for the assessment of NT, as well as for the detection of extreme deformities and the identification of high-risk pregnancies. The proposed method is tested on a large image dataset which shows that the proposed technique has better accuracy than well-known state of the art methods. The proposed SIFT and GRNN based method have an error of 0.02 which is very less compared to the SVM, ANN, NB and KNN.