Middle Plane Research Articles

Computed tomographic assessment of the lacrimal sac fossa in southwest population of Iran

To determine the morphology of the lacrimal sac fossa and bony nasolacrimal duct using computed tomography for obtaining detailed anatomical understanding of the drainage system and utilizing these measurements in planning for dacryocystorhinostomy (DCR) and nasolacrimal duct (NLD) obstruction in normal southwest (SW) population of Iran. One-hundred-sixty-five cases referred for the diagnosis of neuro-ophthalmic conditions were retrospectively studied. Measurements of lacrimal sac fossa were taken on three anatomical sections (upper, middle, and lower planes) utilizing a digital caliper/protractor instrument. Lacrimal thickness and two measurements of maxillary bone thickness were taken at each plane—namely, the “midpoint thickness” and the “maximum thickness.” The anterior extent of the nasal mucosa and NLD width was also evaluated. The mean maximum thickness of the maxillary bone at the three anatomical planes of the lacrimal sac fossa was 4.07 mm, 4.78 mm, and 5.60 mm, respectively. The midpoint thickness of the maxillary bone at each plane was 2.38 mm, 1.99 mm, and 1.68 mm, respectively, in both sexs. The lacrimal bone thickness at each level was 0.76 mm, 0.69 mm, and 0.67 mm, respectively. The proportion of the lacrimal sac fossa comprising the lacrimal bone at lower plane was 43.57% and showed a positive correlation with age (P=0.01). The mean anteroposterior bony nasolacrimal diameter was 5.94 mm with no significant difference between patient sex and age. According to the results, its indicate that performing an osteotomy during DCR could be easier in the Iranian SW population compared to other ethnics.

Experimental study of single-translated field-reversed configuration in KMAX

For collisional merging field-reversed configurations (FRCs), it is desired to have both FRCs tuned to be approximately the same, as well as to optimize each FRC to have high temperature and high translation speed so as to retain most of the equilibrium flux after traveling a distance to the middle plane for merging. The present study reports the experimental study of a single-translated FRC in the KMAX-FRC device with various diagnostics, including a triple probe, a bolometer, several magnetic probe arrays, and a novel 2D internal magnetic probe array. According to the measurements conducted in the present study, a maximum toroidal magnetic field equal to ∼1/3 of the external magnetic field inside the FRC separatrix radius is observed, and the typical parameters of a single-translated FRC near the device’s mid-plane are n e ∼ (2–4)×1019 m−3, T e ∼ 8 eV, T i ∼ 5 eV, r s ∼ 0.2 m, l s ∼ 0.6 m and ϕ p(RR) ∼ 0.2 mWb. The 2D magnetic topology measurement revealed, for the first time, the time evolution of the overall internal magnetic fields of a single-translated FRC, and an optimized operation regime is given in the paper.

A helical grid equivalent circuit model for an intra-layer no-insulation coil

The intra-layer no-insulation (LNI) coil, which has the advantages of self-protection and high magnetic field homogeneity, is of great potential in HTS NMR and MRI applications. Compared to the more commonly-used double-pancake coils, the transient characteristics are more complex due to additional axial current. While the present circuit model cannot accurately describe the geometry of the LNI coil and the internal characteristics of each turn of the coil, a helical grid equivalent circuit model with consideration of types of mutual inductances is proposed in this paper. In the circuit model, details of the coil are characterized with subdivided helical surface elements in each turn, and each helical surface element can be equivalent to corresponding circuit parameters. The circuit model is verified by a comparison experiment with an intra-layer insulation coil. And elaborate current distributions in each turn of the LNI coil can be obtained with this circuit model. Analysis results demonstrate that the azimuthal current and the axial current are always symmetrically distributed about the middle plane, and the radial current is always anti-symmetrically distributed about the midplane. The circuit model can be used to simulate the quench electromagnetic characteristics of the LNI coil in the future.

Averaged Controllability Of Transversely Isotropic Ambartsumyan Plate

In this paper we study the averaged controllability of Ambartsumyan plate made of a transversely isotropic material. Governing equations are based on assumptions of particular theory of anisotropic plates developed by S. A. Ambartsumyan specifically for describing the deformation of anisotropic plates made of material with isotropy plane which, at each point of the plate, is parallel to its middle plane. The Green’s function approach is applied to express the plate normal displacement by means of material parameters (density, Young moduli in both directions of isotropy) which are assumed to be uniformly distributed random variables. Eventually, the averaged controllability condition is reduced to an infinite system of linear constraints with respect to the control action. Three types of particular (heuristic) solutions of the truncated version of the infinite system are discussed. Determination of control parameters is reduced to the solution of a problem of nonlinear programming.

The stable behavior of low thermal conductivity in 1T-sandwich structure with different components

Designing materials with low thermal conductivity (κ) is of demand for thermal protection, heat insulation, thermoelectricity, etc. In this paper, based on the state-of-the-art first-principles calculations, we propose a framework of a 1T-sandwich structure for designing materials with low κ. The 1T-sandwich structure is the same as the well-known transition metal dichalcogenide but with light carbon atoms in the middle plane. Using different atoms to fill the outer positions, a few novel two-dimensional materials are constructed as study cases, i.e., Mg2C, Janus MgBeC, Be2C, and Mo2C. With a systematic and comparative study, the κ are calculated to be 3.74, 8.26, 14.80, and 5.13 W/mK, respectively. The consistent values indicate the stable behavior of low κ in the 1T-sandwich structure, being insensitive to the component. Our study would help design advanced functional materials with reliable heat transfer performance for practical applications, which reduces the influence of unavoidable impurities.

28 GHz and 38 GHz Dual-Band Vertically Stacked Dipole Antennas on Flexible Liquid Crystal Polymer Substrates for Millimeter-Wave 5G Cellular Handsets

Minimizing the size of mobile antennas is necessary for integrating the components inside a mobile device. Wideband and multiband antennas are also required to cover various 5G mobile communication frequency spectra. This article presents a vertically stacked dipole antenna array operating in the 28/38 GHz dual-band. The proposed antenna is small and satisfies the need for wide bandwidth in the form of a dual band. The antenna structure has symmetric 38 GHz band radiators positioned above and below a multilayer substrate, and a 28 GHz band radiator positioned on the middle plane, providing a dual-band antenna structure with small lateral width. Herein, two types of antenna structures are proposed, each with a single-ended and differential feed structure for compatibility with various RF front ends. The single antenna yields −10 dB bandwidth for return loss of 23.9% and 14.4%, and gain of 4.8 and 4.6 dBi at 28 and 38.5 GHz, respectively. The 4-element antenna array yields a gain of 9.0 dBi at 28 GHz and 10.3 dBi at 38.5 GHz. It was fabricated on a flexible substrate and can be bent and inserted into the lateral edge of the terminal. The proposed antenna elements and arrays satisfy the performance factors requisite for millimeter wave 5G communication including compact size, wideband, dual-band, and adequate gain.

Thermoelastic interactions on a thick granular plate with type II thermoelasticity under axisymmetric temperature distribution

This paper deals with the effects of type II thermoelasticity on wave propagation in a generalized thermoelastic granular medium. A two-dimensional thick granular plate with axisymmetric temperature distribution is considered under the generalized theory (with one relaxation time) and type II thermoelasticity. The lower and upper surfaces of the plate are assumed to be stress-free and subjected to a thermal condition. The analytical solution of the different fields like temperature, displacement, stresses, rotation, and couple stresses are obtained by the Laplace transform procedure along with the Hankel transform method. The short-time approximation and Boley’s theorem are used to analyze the fields like temperature and rotation vector in the physical domain. The numerical values are displayed graphically in the middle plane for different models, and comparison illustrates the problem. The study may be helpful in soil mechanics, geophysical-prospecting, seismology, and mining engineering.

DFT-Based Reversible Watermarking Method for Image Ownership Protection

The Performance of Discrete Fourier Transform (DFT)-based watermarking methods has been carefully examined in the literature. Although the watermark in most of the literature was embedded in the DFT magnitudes using bit plane embedding, it was recently embedded in the Direct Current (DC) coefficient in the spatial domain. However, data loss due to rounding and replacement operations are still evident. Therefore, the objective of the method proposed here was to combine previous literature designs to implement a reversible DFT-based watermarking method for image ownership protection using bit plane embedding in the DC coefficient. The watermark was embedded in a middle bit plane of the DC coefficient for each DFT-transformed image block. In order to ensure reversibility and improve the security level, a combination of double Feynman and XOR gates was used to shuffle the watermark bits. The results revealed that the 8th (PSNR/SSIM = 32dB/0.8826), the 9th (PSNR/SSIM = 38dB/0.0.9587), and the 10th (PSNR/SSIM = 44dB/0.9917) bit planes for block sizes of 4×4, 8×8, and 16×16, respectively, were the best bit planes showing good imperceptibility and resistance to compression, filtering, and noise attacks. In conclusion, embedding the DC coefficients rather than all the magnitudes has influentially increased the watermarking robustness. In contrast, embedding the DC coefficients in the frequency domain rather than the spatial domain reduced the image’s structural contents distortion. Furthermore, the proposed method for grayscale images is effective in applications where reversibility is desired. However, further studies to find colored images’ reversible methods are recommended.

BSD-Guard: A Collaborative Blockchain-Based Approach for Detection and Mitigation of SDN-Targeted DDoS Attacks

Software-Defined Networking (SDN) enhances the flexibility and programmability of networks by separating control plane and data plane. The logically centralized control mechanism makes the control plane vulnerable in both single and multiple controller scenarios. Malicious third parties can exploit vulnerabilities of reactive forwarding mode to launch distributed denial-of-service (DDoS) attacks against SDN controllers. Unfortunately, existing DoS/DDoS solutions under single controller can not afford effective performance under multiple controllers due to the absence of cooperative detection and mitigation. To solve the above problem, we propose a blockchain-based SDN-targeted DDoS defense framework (BSD-Guard) that can provide cooperative detection and mitigation mechanism to protect SDN controllers. BSD-Guard introduces a blockchain-based secure middle plane between control plane and data plane. The secure middle plane calculates the suspect rate of new flows based on the collected packets’ information and reports suspect lists to blockchain for immutably storing and sharing. Besides, the smart contract deployed on blockchain in advance constitutes collaborative defense strategies based on the suspect lists reported from multiple SDN domains. When receiving defense strategies, the secure middle plane converts them to specific flow table actions and installs actions into relevant switches. The experimental results indicate that BSD-Guard can efficiently detect DoS/DDoS attacks in multiple controllers scenario and issue precise defensive strategies near the source of attack by identifying the attack path.

A micro-CT analysis of radicular dentine thickness in mandibular first premolars presenting C-shaped root canals: Identification of potential danger zones.

To describe the radicular dentine thickness in mandibular first premolars presenting C-shaped root canals, to identify the canal walls with less thickness as potential danger zones. In addition, to describe the internal and external anatomical characteristics of these teeth and associate them with the dentine thickness. A total of 70 mandibular first premolars presenting C-shaped root canals were examined. Their internal morphology was analysed using Vertucci's and Fan's criteria, and their external morphology was analysed using the ASUDAS score. Besides, the dentine thickness around the root canals was two/three-dimensionally determined at five root planes and quantified in the distal and the mesial aspects. According to Fan's, ASUDAS, and Vertucci's classifications, the most common canal configurations were category C3, grade 3, and type V, respectively. In Vertucci's type III anatomy, the mesial root wall of the lingual canal showed significantly less dentine thickness than the distal wall in the middle plane (p=.031). Similarly, in Vertucci's type V anatomy, significantly less dentine thickness was observed in the mesial root wall of the buccal and lingual canals in the middle plane (p<.001) and the buccal canal in the middle-apical plane (p=.014) than the distal root wall of these canals. In teeth with ASUDAS grade 3 and 4 scores, significantly less dentine thickness was observed in the mesial in comparison with the distal root wall of these canals. These differences were demonstrated in the middle and middle-apical planes (p<.001) of grade 3 teeth and the middle-apical plane (p<.001) of grade 4 teeth. In these root planes, the Ver1-AS3 and VerV-AS3 combinations presented a 4-times greater risk of presenting walls with a critical dentine thickness of 0.6mm (odds ratio [OR]=4, p=.025) than the combinations Ver1-AS2, VerV-AS2, VerV-AS4, and VerIII-AS3. The root canal system configuration of mandibular first premolars with C-shaped canals showed a wide range of anatomical variations. The lowest dentine thickness was located in the mesial wall of the canals in the middle and apical root thirds of Vertucci's type III and V anatomies and in teeth with deep radicular grooves scored as ASUDAS grades 3 and 4. In the middle and middle-apical planes, the presence of the combinations Ver1-AS3 and VerV-AS3 showed a high risk of presenting a critical dentine thickness of 0.6mm. Therefore, these root canal walls with less dentine thickness represent potential instrumentation danger zones in mandibular first premolars with C-shaped canals.

Experimental study on fiber suspension in a centrifugal pump by PIV

Abstract To study the influence of fiber particles on the flow field within the passages of an open impeller centrifugal pump, an experiment was performed. The hair fiber was used as solid particle phase in this experiment. After measuring the performance characteristic and PIV data, the flow field in impeller was measured and analyzed. It was shown that at the concentration of 0.1%, a varied distribution of relative velocity from different flow channels was observed. The outlet velocity of the impeller in the second flow channel was obviously higher than that in the first flow channel. The variation of the relative velocity near the hub tended to be consistent at the position of the front plane and the middle plane of the impeller. At 0.2% concentration, the relative velocity at the suction surface of the two channels changes more sharply than the other positions. Within the second channel, it was found that the relative velocity under low flow condition was obviously higher than that under rated and large flow rates. Under different concentrations, the increase of the relative velocity at low flow rate changed intensely compared with the other two conditions. The low velocity zone will be formed near the middle part of the suction surface of the flow channel which gradually decreases with the increase of the flow rate. The external characteristic test shows that the efficiency of the pump and the drag reducing feature increase with the increase of concentration.

Free vibration analyses of functionally graded plates based on improved refined shear and normal deformation theory considering thickness stretching effect using Airy stress function

In this paper, an improved refined shear and normal deformation theory is used in order to investigate the vibration behavior of functionally graded rectangular plates. In this theory, displacements of various points of plate are assumed to be due to in-plane displacements of the middle plane and transverse displacement. Transverse displacement is divided into three parts: bending, shear, and thickness stretching. Using the Airy stress function, corresponding to the compatibility equation, and employing the extended Hamilton’s principle, in-plane displacements are omitted from the equations of motions. Thus, the proposed approach uses only three-unknowns in the displacement field. The results of vibration analysis using the proposed approach are in excellent agreement with three-dimensional and quasi-three-dimensional solutions containing a greater number of unknowns to consider the thickness stretching effect. Static and dynamic behavior of wide variety of thin and thick functionally graded plates can be studied using the proposed approach in which not only the number of variables is reduced, but also the contribution of bending, shear, and thickness stretching are completely clarified.

ДИНАМИКА ПУЧКА ЗАРЯЖЕННЫХ ЧАСТИЦ В ТРАНСАКСИАЛЬНОМ ЗЕРКАЛЕ

The behavior of a beam of charged particles formed by a point source located in the middle plane of the mirror is considered. The calculation of the trajectories of particles was carried out by numerical integration of dimensionless Newton equations. The electrostatic field of the three-electrode mirror was described by an analytical expression for the potential with good accuracy. It is shown that as a result of reflection in a three-electrode transaxial mirror, it is possible to achieve both spatial and energy time-of-flight focusing. Two modes of vertical beam focusing are considered.

Modeling of partially delaminated composite plates resting on two-parameter elastic foundation with improved layerwise theory

In this work, we aim to build the mathematical model for delaminated composite plates resting on elastic foundation by means of improved layerwise theory and finite element implementation for free vibration analysis. The proposed model takes into account the transverse normal and shear deformation of the elastic foundation so as to investigate their effect on the dynamic characteristics of delaminated plates. The four-node plate element is used for the finite element formulations with Langrage interpolation functions for in-plane structural unknowns and Hermite cubic interpolation functions for out-of-plane structural unknowns. The delamination is simulated by means of Heaviside unit step functions allowing for the discontinuity of displacement fields. The effects of both longitudinal locations and interfacial locations of delamination are investigated. The results show that when the delamination located closer to the clamped end and at the middle plane, it has much more severe influence on its natural frequencies. The foundation parameters also have significant effect on the natural frequencies and frequency shift due to delamination. Different layup stacking sequences are also considered in this study.

Exchange spring-like inhomogeneous states in a ferromagnetic wire with current

Transverse structure of magnetization in a ferromagnetic film induced by magnetic field of electric current has been analyzed. Two steps of arising exchange spring evolution are shown. The first one (weak current) is gradual twisting of magnetization aside from the wire axis. Above some critical current the transient area is compressed and localized near the middle plane. In presence of additional conductive layer the transient structure becomes asymmetric resulting to non-zero lateral component of the net magnetization. It is shown also that the mentioned asymmetry can provide additional displacement of domain walls after the electric current pulses. Keywords: spintronics, domain wall dynamics, exchange spring, ferromagnet.

Aberration correction of aperture-divided off-axis simultaneous polarization super-resolution imaging optical system

According to the requirements for broadband simultaneous polarization high-resolution imaging, a divided-aperture simultaneous polarization super-resolution imaging system based on reflective free-form surface optical system and digital micro-mirror device is proposed. It has the advantages of wide working wavelength band, simultaneous imaging of multiple polarization states, single detector, high resolution and lightweight. The aberration correction principle and design optimization method of the optical structure for this imaging system are given. The Wassermann-Wolf theory is further developed, and the reflective Wassermann-Wolf differential equations that eliminate a variety of aberrations are derived. At the same time, combined with Seidel aberration theory and using iterative method, the distortion elimination boundary condition is added when solving the Wassermann-Wolf equation. Through the iterative method, the optical initial structure is obtained, which can correct spherical aberration, coma, astigmatism and distortion at the same time. The initial structure is subjected to off-axis treatment and further optimized, and the user-defined optimization evaluation function is written to strictly control the position of the light falling point of each sub aperture and each field of view on the middle image plane and the final image plane, so as to effectively suppress the distortion in the final system and avoid the mismatch error between the mirror element and the pixel in the process of super-resolution reconstruction. The reconstruction quality can be improved. Finally, the design of the four-sub-aperture free-form surface off-axis reflective super-resolution imaging optical system is completed, which possesses a large relative aperture (&lt;i&gt;F&lt;/i&gt;# = 2.5) and compact structure. The imaging quality of each polarization channel is close to the diffraction limit. The above aberration correction principle and the image quality optimization method can effectively guide the design of the wide band simultaneous polarization super-resolution imaging optical system.

Mode decomposition in DCB and ENF tests with geometric and material assymetry

Mode decomposition in interlaminar fracture tests initially designed for pure modes I and II as Double Cantilever Beam (DCB) and End Notcehd Flexure (ENF) is analyzed. In the initial proposal of those tests crack arms have geometric and material symmetry and the crack advance occurs through the middle plane of the laminate. In the current study, the possibilty of crack arms of different materials or with different thickness is included. Two mode decomposition criterions are considered after the analysis of a slice near the crack tip. Those criterions are based on the stress and displacement state in the non-cracked zone near the crack tip. Two points that before the crack advance were the same point are named homologous. When the cohesive zone is developing, the stresses in homologous points are the same due to the principle of action and reaction. Nevertheless, relative displacement can be normal, related to mode I, tangential, related to mode II, or a combiantion of both, related to mixed mode I-II. In the present work the relative tangential displacement related to mode III is not considered. The contributions to the energy release rate corresponding to bending and shear in each mode are analyzed. The results obtained are applied to asymmetric DCB and ENF tests.

Comparative analysis on the structure, electronic and magnetic properties of SrRuO3 and PbRuO3

The structure, electronic and magnetic properties of SrRuO3 and PbRuO3 are studied by using density functional theory in the local spin density approximation. The lattice constants of orthorhombic SrRuO3 and PbRuO3 with a Pbnm space group have a > b, different from most of other ABO3 structures with a < b. We obtain two reasons about a > b for SrRuO3 and PbRuO3: One is that the horizontal middle plane of the oxygen octahedra deforms from square to rectangle, resulting in the side length of rectangle along x direction, aoct, is larger than that along y direction, boct; The other is the tilting angle of the oxygen octahedra having θ < arccos (boct/aoct). SrRuO3 and PbRuO3 with similar structure should have similar magnetic ground states. But SrRuO3 is ferromagnetic, while PbRuO3 is paramagnetic. Our results show that the orbital hybridization of Pb–O is much stronger than that of Sr–O, which lead to the broaden bandwidth near Fermi level. This is the main reason for the different magnetic ground states of SrRuO3 and PbRuO3. The calculations for PbRuO3 with Pbnm and Imma structures have considered the spin-orbit coupling effect, the calculated results show that the ground states of Pbnm and Imma PbRuO3 are both paramagnetic metals.

Effect of nylon fabric reinforcement on the mechanical performance of adhesive joints made between glass and GFRP

The use of reinforcements in adhesive joints makes the stress distribution more uniform, improving their mechanical performance and adhesion. The present paper aims to verify the effectiveness and efficiency of the insertion of nylon 6 fabric in the adhesive layer, to study their applicability and functionality in building components. The increase in stiffness achieved by applying nylon 6 fabric in the adhesive layer between glass and GFRP pultruded profiles and steel laminates applied to GFRP beams is investigated. Three different epoxy adhesives and one epoxy resin are used and compared. Three different types of tests are carried out in order to study the different properties of the reinforcement system: tensile tests on GFRP/GFRP single-lap adhesive joints, with and without nylon fabric reinforcement; tensile tests on double-lap adhesive joints between float glass and pultruded GFRP profiles reinforced with nylon fabric according to four configurations (in the middle plane of the adhesive layer, on the glass surfaces, on the GFRP surfaces, on both GFRP and glass configurations) to verify the influence of its position; three-point bending tests on long GFRP tubular profiles reinforced with steel plates and nylon fabric in different configurations, to study resistance to bending loads. The results from the experimental campaign show the effectiveness of the reinforcement system using nylon fabric 6. In general, both a reduction in ultimate strength and an increase in joint stiffness compared to unreinforced configurations are observed.

Surface segmentation of plate heat exchanger corrugated sheet based on discretization – Recognition strategy

Segmentation of region of interest (ROI) is an important content in automated optic inspection (AOI). Aiming at the segmentation of ROI corresponding to various defects on the corrugated sheet of plate heat exchanger (PHE), a method based on discretization - recognition strategy is proposed. Corrugated sheet is a large complex curved surface. We find a way to regard it as a combination of several inclined planes and noncontiguous horizontal planes innovatively. Through using a typical AOI coaxial imaging system, the image marked by different gray values is obtained firstly. The inclined plane region is segmented according to the gray feature. Each horizontal plane region is discretized at the same time. Then, a method based on web crawler is proposed to recognize the specific category of each horizontal plane region. Finally, the surface of the corrugated sheet is divided into four types--inclined plane, high horizontal plane, middle horizontal plane and low horizontal plane. The experimental results demonstrate the great effect.