Planar Elements Research Articles

A novel reciprocating cluster magnetorheological polishing device: Design and investigation of removal model

In the traditional magnetorheological polishing of flat planar elements, there have been problems like low efficiency and uneven surface. To improve the surface quality of optical glass and explore the material removal mechanism, a novel reciprocating cluster magnetorheological polishing (MRP) device was designed with a magnetic field consisting of six curved permanent magnets and one static magnetic finite element for analysis. By analyzing the forces and motion behaviors of single abrasive particles during the polishing process, a novel removal model was developed and the effects of the main parameters on the material removal mechanism were investigated. The experiments ware conducted on the K9 glass through the polishing process by this proposed device and traditional cold working separately. The results showed that reciprocating cluster MRP for 120 min was able to achieve a surface roughness of 2.7 nm, a Peak to Valley (PV) value of 0.689 fr (216 nm) and a Root Mean Square (RMS) value of 0.077 fr (24 nm), respectively, which made a significant improvement on the conventional cold working. Therefore, the proposed device and novel polishing process could effectively reduce the surface roughness value and the PV value of K9 glass, while improving both the polishing efficiency and accuracy of optical components.

Versatile iodine-doped BiOCl with abundant oxygen vacancies and (110) crystal planes for enhanced pollutant photodegradation

Crystal plane regulation, defect engineering, and element doping can effectively solve the problems of large band gaps, poor light absorption, and fast recombination of BiOCl. In this work, iodine-doped BiOCl (I/BiOCl) nanowafers with abundant (110) crystal planes and oxygen vacancies (OV) were prepared by a simple hydrothermal method and assessed for pollutant photodegradation. I/BiOCl with a molar ratio of I to Cl of 0.6 (I0.6/BiOCl) degraded under visible light 95.8% of the toxic dye rhodamine B and 85.1% of the persistent antibiotic tetracycline in 5 and 10 min, respectively. In comparison, unmodified BiOCl photodegraded only between 42.0% and 48.2% of these critical water pollutants. Furthermore, I0.6/BiOCl was highly stable with most of its photocatalytic activity remaining after 4 cycles. Three reasons explain the excellent photodegradation properties of I0.6/BiOCl. First, the doped photocatalyst grew abundant (110) crystal planes, which inhibits the recombination of photogenerated electron-hole pairs. Second, the large quantity of OV present in I0.6/BiOCl increased active sites for reactive oxygen species generation, improved photogenerated charge separation, and pollutants adsorption. Lastly, I0.6/BiOCl had a modified electronic band structure enhancing light absorption. Overall, these results describe a promising photocatalyst capable of degrading efficiently major pollutants with different structures.

Kasteleyn cokernels and perfect matchings on planar bipartite graphs

The determinant method of Kasteleyn gives a method of computing the number of perfect matchings of a planar bipartite graph. In addition, results of Bernardi exhibit a bijection between spanning trees of a planar bipartite graph and elements of its Jacobian. In this paper, we explore an adaptation of Bernardi’s results, providing a simply transitive group action of the Kasteleyn cokernel of a planar bipartite graph on its set of perfect matchings, when the planar bipartite graph in question is of the form $$G^+$$ , as defined by Kenyon, Propp and Wilson.

Modeling of a Compact Dual Band and Flexible Elliptical-Shape Implantable Antenna in Multi-Layer Tissue Model

A flexible antenna of compact size with a dual band elliptical-shape implantable is designed for biomedical purposes. The suggested antenna has an elliptical shape to be more comfortable for being implanted in human tissue. The implantable antenna is printed on RO3010 substrate with 2 mm as a thickness and 10.2 as a dielectric constant. It consists of an active planar C-shaped element and a parasitic planar inverted C-shaped element. The proposed antenna is designed with a major axis radius of 12 mm and a minor axis radius of 8 mm. It operates in dual bands: The Industrial Scientific and Medical band (ISM) [2.4 GHz–3.5 GHz] and Medical Implant Communications Service band (MICS) [394 MHz–407.61 MHz]. A short-circuited pin is used to minimize the antenna’s overall size and for further size reduction a capacitive load is used between the radiator and the ground plane. For biocompatibility, a thin-thickness layer of Alumina is used as a superstrate. The suggested antenna is tested in a multi-layer tissue model and the Specific Absorption Rate (SAR) value is computed. The proposed antenna was fabricated, and the reflection coefficient is measured and compared with simulated results.

Shape dependence of all-dielectric terahertz metasurface.

All-dielectric metasurfaces have been attracting attention in the terahertz spectral range for low-loss planar optical elements such as lenses, beam splitters, waveplates, vortex plates, and magnetic mirrors. Various shapes of meta-atoms have been used in many studies; however, no systematic comparative study of each shape has been reported. The optical properties of various shapes of metasurfaces are reported in this work using finite difference time domain simulation. The phase of a pillar-type all-dielectric metasurface is mainly determined by the cross-sectional area, rather than its detailed shape. Consequently, in the square lattice geometry, the square shape meta-atom performs best in terms of full phase control at the lowest pillar height with negligible polarization dependence. Furthermore, we compare the transmission, phase, and polarization dependence of the hexagonal and square lattices. Square-shape metasurface successfully realizes subwavelength focusing metalens and vortex plate.

Controlled Self-Assembly of Low-Dimensional Supramolecular Systems Based on Double-Decker Lanthanide Phthalocyaninates

Possessing unique physicochemical properties, phthalocyanines are widely used as active components of supramolecular ensembles and nanomaterials. The functional properties of phthalocyanine-based materials are governed by not only the structure of their discotic molecules, but also the character of their intermolecular interactions, which determine both the self-assembly mechanism and the structure of such systems. This review discusses the experimental approaches, which are based on the notions of colloid and coordination chemistry that enable one to control intermolecular interactions in low-dimensional supramolecular ensembles based on phthalocyanines and metallocomplexes thereof. Using double-decker crown-substituted lanthanide phthalocyaninates as an example, it is shown how one- and two-dimensional nanomaterials with different properties can be obtained from the same type of building blocks employing a set of colloid-chemical methods. Such materials are, in particular, capable for controlled absorption of visible light in ultrathin films and can be employed as conducting one-dimensional components of planar elements for organic electronics.

Design and Synthesis of Pyrrolidinyl Ferrocene-Containing Ligands and Their Application in Highly Enantioselective Rhodium-Catalyzed Olefin Hydrogenation.

Herein, we report the design and synthesis of a series of chiral pyrrolidine-substituted ferrocene-derived ligands. The proficiency of this novel structural motif was demonstrated in the Rh-catalyzed asymmetric hydrogenation of dehydroamino acid esters and α-aryl enamides. The products were obtained with full conversions and excellent levels of enantioselectivities of up to >99.9% ee and 97.7% ee, respectively, using a BINOL-substituted phosphine-phosphoaramidite ligand which possesses planar, central, and axial chirality elements.

Front and back surface measurement of the transparent planar element based on multi-frequency fringe deflectometry.

As a highly accurate metrology, phase measuring deflectometry (PMD) can be used for in-situ surface shape measurement. However, due to the reflection off the back surface, PMD cannot measure both the front and back surfaces of the transparent planar element simultaneously. Therefore, this paper proposes a method for measuring the front and back surfaces of the transparent planar element. The phase distribution corresponding to the front and back surfaces can be firstly acquired by multi-frequency fringe deflectometry. Then, the front and back surface shapes can be obtained by inverse ray-tracing and nonlinear optimization. Numerical simulation and experiment verify the proposed method. The surface shape of window glass with a thickness of 10 mm is measured in the experiment. The surface shape error is around 50 nm in the root mean square with a diameter of 51 mm.

Implementation of the Results of Experimental Studies with the Use of the Sclerometric Method of Plane Elements in Wooden Buildings

Wood is one of the basic building materials. It is a completely biodegradable raw industrial commodity, the resources of which, with proper forest management, are virtually inexhaustible. Additionally, its acquisition and processing does not require large inputs of fossil fuels. At the same time, forest areas which we obtain wood from neutralize the negative effects of producing and acquiring other raw materials, as one hectare of pine forest (the most popular in Poland) can absorb approx. 20–30 tons of CO2. Wood is characterised by low thermal and electrical conductivity, having simultaneously high sound insulation, which perfectly meets the requirements of the present market and its regulations. This study aimed at verifying the technical parameters of wood, i.e., its bending strength, with the use of an innovative method of the correlation between the bending strength measured along and across wood fibres. The procedure was envisaged as effective for testing the strength of beams in historic buildings, in which—due to their valuable structure—only a limited number of sample holes can be made. The aim of this experiment was to create tables and diagrams, from which, based on the correlation between the side and the head of the beam, using in situ tests and the sclerometric method, it will be possible to derive the bending strength of existing wooden beams. In the study of spruce and pine wood, a correlation between the recess from the side and the recess from the head was found, ranging from 0.64 to 0.76, with an average of 0.72 for spruce elements, and 0.66–0.84, with an average of 0.70 for pine elements. This means that when testing an element fixed in a building, measuring the parameters from the head of the beam with a Schmidt hammer (often such elements are more easily accessible, i.e., on the building facade), the obtained values should be multiplied by 0.72 for spruce elements and by 0.70 for pine elements to obtain the strength of the beam. The authors of this article indicate that the confirmation of this observation requires conducting further research on various types of wood. It should also be noted that the material collected from one batch of sawn timber had a different structure, which was proved by analysing it using SEM imaging. Modeling wood numerically is, to some extent, a simplified issue that assumes wood to be an orthotropic, homogeneous (homogeneous) material. In fact, wood is an anisotropic, very heterogeneous material. The analysis of wood (on the technical scale, construction wood) as an anisotropic material is practically impossible. Adopting wood as an isotropic material is too simplistic. Therefore, the most appropriate methods of strength testing are destructive methods, as all non-destructive methods should not be used without verifying the results with other methods. The results obtained by non-destructive testing pose great difficulties in their interpretation. Obtaining reliable results of experiments entails collecting a large number of research samples. The method described in this paper will allow for obtaining the necessary data for effective expertise assessment regarding the safety level of structural elements in historic wooden load-bearing structures, which is crucial for making conservation decisions.

Parasitic reflection separation deflectometry based on harmonic analysis

In the measurement of transparent planar element using deflectometry, the fringe patterns reflected off the double surfaces of transparent planar element are superimposed on the camera, causing the phenomenon of parasitic reflection. The parasitic reflection makes it difficult for traditional deflectometry to accurately obtain the front surface shape. Previous solutions suffer from inability to reliably measure the element with thickness less than 10 mm. In practice, modulated by the nonlinear response, the signal captured by the camera contains higher-order harmonics, whose frequency difference is larger than that of the fundamental. Therefore, a novel method based on harmonic analysis is proposed. This parasitic issue of thin transparent element can be eliminated by analyzing the harmonic component in power spectrum. The surface shape of element with thickness of 5 mm is measured in experiment. The measurement error is around 80 nm in RMS with a diameter of 52 mm.

Planar Alvarez tunable lens based on polymetric liquid crystal Pancharatnam-Berry optical elements.

Virtual reality (VR) and augmented reality (AR) have widespread applications. The vergence-accommodation conflict (VAC), which causes 3D visual fatigue, has become an urgent challenge for VR and AR displays. Alvarez lenses, with precise and continuously tunable focal length based on the lateral shift of its two sub-elements, are a promising candidate as the key electro-optical component in vari-focal AR display systems to solve the VAC problem. In this paper, we propose and fabricate a compact Alvarez lens based on planar polymetric liquid crystal Pancharatnam-Berry optical elements. It can provide continuous diopter change from -1.4 D to 1.4 D at the wavelength of 532 nm with the lateral shift ranging from -5 mm to 5 mm. We also demonstrate an AR display system using this proposed Alvarez lens, where virtual images are augmented on the real world at different depths.

Analysis on affecting factors of the ribbon fluctuation in Array-MRF

Large aperture planar optical elements are required in high power laser systems, and the mid-spatial frequency error of the surface of the high-power laser component will affect the normal operation of the high-power laser system. In recent years, there are many new MRF devices, but these devices only improve the removal efficiency of polishing materials and ignore the stability of MRF tools. As we all know, the fluctuation of the MRF polishing ribbon will affect the stability of the removal function, which will make the surface of the processed component produce the mid-spatial frequency error. Therefore, based on the array magnetorheological pole structure newly developed in our laboratory, this paper tests its magnetic field distribution and studies the influencing factors of array magnetorheological ribbon fluctuation. Based on the magnetic field force, the effects of magnetorheological fluid flow, polishing wheel speed, and magnetic pole structure on ribbon fluctuation are analyzed. Finally, by using the improved array magnetorheological device to obtain a stable removal function, the volume removal efficiency of fused silica reaches 0.022mm3/min, which verifies the feasibility of the improved device and doubles the removal efficiency of magnetorheological finishing of a single ribbon. Therefore, we use controlled magnetorheological processing flow and speed to control ribbon fluctuations and designing the magnetic pole structure, to control the stability of magnetorheological processing.

Research on 3D Jewelry Design Based on Virtual Reality Technology

The existing three-dimensional jewelry design method has the problem of imperfect three-dimensional display model, which leads to a high product wastage rate. A three-dimensional jewelry design method based on virtual reality technology is designed. From the perspective of diversified production needs, the jewelry production and processing process is obtained. CNC plate making is adopted to identify the technological characteristics of plane elements. The digital three-dimensional model is taken as the design carrier, and the three-dimensional display model is constructed by virtual reality technology. Experimental Results. The average product loss rate of the three-dimensional jewelry design method in this paper and the other two three-dimensional jewelry design methods were 5.523%, 8.043%, and 8.237%, respectively, indicating that the performance of three-dimensional jewelry design method is more perfect after the combination of virtual reality technology.

Planar liquid crystal optics for simultaneously surface displaying and diffraction-limited focusing

Abstract Planar optical elements have attracted widespread attentions because of their precise light modulation. Liquid crystals (LCs) are well known for their applications in the current displaying field, and show great potential in planar optical elements with the development and innovation of LC micro-operation technology. However, previous researches on LC elements mainly involved only one type of optical manipulation, which inevitably limited the functional diversity. In this work, we propose a multifunctional LC element which integrates the surface display into a binary-phase focusing lens by controlling the complex amplitude of the incident light. The light modulation of the anisotropic LC molecule satisfies a sinusoidal variation, which can be regarded as the combination of a continuous amplitude modulation and a binary phase modulation. The element with millimeter size is then fabricated, and the experimental measurements agree well with our design with a high-definition surface pattern and high-quality optical focusing/imaging performance. Furthermore, as the complex amplitude modulation changes from sine to cosine function after rotating the sample by 45°, a bifocal lens with two different focal lengths is also demonstrated. We expect the proposed multifunctional LC elements can find applications in information multiplexing, image displaying, etc.

An optical-mechanical integrated modeling method of solar dish concentrator system for optical performance analysis under service load

Solar dish concentrator system (SDC system) is an optical device that provides a high-temperature heat source for Stirling engine. However, due to its heavy structural and large windward area, it is easy to be deformed by self-weight or wind load during service, which leads to changes the mirror shape and receiver position of SDC system, thus deteriorating its optical performance. In order to predict and evaluate the optical performance and flux distribution of SDC system under service load, this paper proposes an optical-mechanical integrated modeling method considering the deformation of SDC system by combining the finite element method and ray-tracing method. It discretizes mirror surface into a large number of plane element, and directly establishes the optical model by its deformation information, which is suitable for any concentrator using mirrors. The modeling process is derived, including the optical model of concentrator under non-deformation and deformation, spatial position model and flux distribution model of the receiver, mirror shape error model. Finally, the modeling method is verified by examples and literature results, the flux distribution and mirror shape error calculated by this method are in good agreement with comparison results, and relative error ranges from 0.6% to 5.6%.

Sub-diffraction focusing by a meta spiral zone plate

The sub-diffraction focus has been widely studied because of its wide application in the fields of optical lithography and super-resolution imaging. The methods based on the traditional refractive elements to achieve sub-diffraction focal spots face the problem of large volume, large mass and difficult alignment. Although diffractive optical elements can achieve the combination of multiple phase modulation functions, the polarization modulation cannot be achieved by such elements. As a planar element to achieve integrated modulation of phase and polarization, the metasurface has the potential to further miniaturize the sub-diffraction focusing system and eliminate alignment errors. In this article, we demonstrate the meta spiral zone plate, which converts the incident linearly polarized beam to an azimuthally polarized beam and focuses the latter into a sub-diffraction solid spot. The meta spiral zone plate with a diameter of 600 μm and a numerical aperture of 0.8 working at the wavelength 405 nm is designed and verified experimentally. The simulated full width at half maximum (FWHM) and measured FWHM of the focus spot are 0.6λ and 0.65λ. The simulated and measured efficiencies are 37.69% and 15.18%, respectively. Meanwhile, the effects of the incident beam's incident angle and polarization orientation on the focal spot are also investigated. Our proposal eliminates the alignment errors in the traditional methods and further simplifies the optical systems realizing sub-diffraction focusing, which may have great potential applications in super-resolution focusing and optical manipulation.

Seismic and failure behavior simulation for RC shear walls under cyclic loading based on vector form intrinsic finite element

Seismic performance and failure mode simulations for reinforced concrete (RC) structures are impeded by large deformations and material nonlinearity particularly when subjected to the combined action of compression, bending and shear. Structural deformation and failure analysis based on traditional finite element (FE) often fails for the small–deformation assumption and global equilibrium. Moreover, it remains difficult to obtain convergence results for the existing FE methods by applying general concrete constitutive models for the complicity of anisotropic materials. To simulate the hysteretic performance and the damage development process of the RC shear wall under cyclic loading, the vector form intrinsic finite element (VFIFE) method with independent particles was adopted and combined with the two-directional concrete constitutive model considering the loading and unloading rules to perform large deformation and damage estimations. Concrete planar triangular element and fiber element for steel bar equipped with the hysteretic constitutive models were used to model six RC shear walls with different design parameters. Owing to the merits of avoiding repeated accumulation of the global stiffness matrix for vector mechanics, the planar structural behaviors involving biaxial stress–strain and loading–unloading behavior were numerically demonstrated. The simulated results were in close agreement with the experimental tests, including the hysteretic loop, skeleton curve, bending–shear deformation, and damage mode. This research also provides successive evidence for damage process simulation by VFIFE for RC structures under seismic loading considering a comprehensive constitutive relation.

High-Speed Interconnects: History, Evolution, and the Road Ahead

An integrated circuit (IC), or chip, is a set of electronic circuits and components placed on a tiny planar silicon (Si) semiconductor substrate. These electronics circuits and components are electrically connected to one another with the help of planar and vertical conductor elements known as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">interconnects</i> . This article presents a detailed overview of the evolution of interconnects, highlighting the technological milestones that have been achieved during the past four decades. Interconnects form the backbone of signal communication among devices on a chip and between chips on a printed circuit board (PCB). The layout and design of interconnects on an IC are vital to the chip’s performance, functionality, reliability, efficiency, and overall fabrication yield.

Deep Learning for Securing Software-Defined Industrial Internet of Things: Attacks and Countermeasures

Software-defined networking (SDN) has become an attractive solution to carry out centralized and efficient control in Industrial Internet of Things (IIoT). However, its security has received little attention when applied to IIoT, and no comprehensive consideration has been given to attacks against forwarding nodes (FNs), the basic elements of the data plane. Therefore, in this article, we aim to investigate attacks against FNs from multiple perspectives in software-defined IIoT. To the best of our knowledge, we are the first to systematically consider this kind of attacks. Since it is difficult to predeploy all defense methods against various attacks, we propose a deep reinforcement learning (DRL)-based general attack tolerance scheme to guide the benign traffic flow bypass the attacked FNs. Furthermore, in view of the situation that the real data set is rare and the standard model-based data set is likely to be impractical, we use generative adversarial network (GAN), a representative deep generative model (DGM), to flexibly generate real-like network traffic for more sufficient and effective experimental verification on the attack tolerance scheme. Experimental results show that our proposed scheme can significantly improve the successful arrival rate of IIoT traffic and achieve near-optimal results.

Design of Conformal Array of Rectangular Waveguide-Fed Metasurfaces

We present a systematic design method for a cylindrical conformal array of rectangular waveguide-fed metasurfaces. The conformal metasurface consists of multiple curved rectangular waveguides loaded with metamaterial elements—electrically small apertures—inserted into the upper conducting walls of the waveguides. Each element radiates energy into free space to contribute to an overall radiation pattern. Thus, the geometry or electrical configuration of each of the elements needs to be tailored to generate a desired pattern. Generally, due to difficulties in modeling the effect of curvature, the design of conformal metasurface arrays has relied on full-wave simulations or experiments. In this study, we propose a design method utilizing the semianalytical model of a planar metasurface accounting for metamaterial elements’ locations and orientations over a curved surface. Although approximate, we demonstrate that the alteration along with the framework of dipolar modeling of planar elements can be used for the analysis of conformal arrays with small curvature. We then design a conformal array metasurface using the method combined with the covariance matrix adaptation evolution strategy (CMA-ES) optimizer. Through numerical simulations, we confirm the validity of the proposed design method. Applications include the design of metasurfaces for radar, communications, and imaging systems for mobile platforms.