Step Structure Research Articles

Atomic-scale mechanism of rhombohedral twinning in sapphire

Deformation twinning is a fundamental plastic deformation mode in crystals. Upon twinning, individual atoms must move in different directions to satisfy the twin symmetry, which is called atomic shuffling. However, actual atomic motions during shuffling are still unknown, especially for ionic compounds. Here, we report the dynamic twinning behavior dominated by the atomic shuffling in sapphire (α-Al2O3). The propagation and annihilation of twins are revealed to be mediated by migration of step structures on the matrix/twin interfaces. The step migration is driven by cooperative motions of a group of five atoms with relatively few recombination of Al–O bonds. Our findings imply that the atomic shuffling associated with twinning is determined by a collective property of a group of several atoms.

Case study: Purdue University's "Clapping Circle": An acoustical investigation

The perplexing acoustical properties of a landscape architecture feature of Academy Park on the Purdue University campus have long been the subject of speculation. The feature, known informally as the "Clapping Circle", consists of sixty-six concentric rings of stone tiles. When someone claps while at the middle of the circle, they hear a high-pitched squeak immediately afterwards. Experiments were conducted by the Purdue student chapter of the Acoustical Society of America to characterize this effect. The response to a clap played from an omnidirectional speaker placed at the center of the circle was recorded using a microphone positioned above the loudspeaker. Spectrograms of the recorded responses revealed the squeak to consist of a descending tone and its harmonics. This tone disappeared from the spectrogram when the tiles were covered with absorbing blankets. A model based on scattering from the bevels between the tile rings reproduced the descending frequency of the squeak. Similarly to famous stepped structures with notable acoustics, the tiles were found to scatter sound best when the wavelength was not larger than the tiles' spatial period. Thus, it was concluded that the squeak is an example of an acoustical diffraction grating which creates a repetition pitch caused by scattering from the tile formation.

Improved ES Cell-Derived Erythroid Cell Generation with Robust β-Globin Production through ES-Sacs

In vitro erythroid cell generation represents an important model and potential therapeutic strategy for hemoglobin disorders, including sickle cell disease. Traditional methods for erythroid cell generation from human embryonic stem cells (hESCs) via embryoid body or monolayer culture methods result in mainly ε-globin and γ-globin production with very low amounts of β-globin. Recently, we have demonstrated hESC-derived erythroid cell generation via hemangioblast-like ES-sacs, allowing for definitive β-globin production at detectable protein levels by HPLC (Stem Cells, 2016).In this study, we sought to improve ES-sac generation using defined serum-free Knockout Serum Replacement (KSR) instead of fetal bovine serum (FBS), to allow for more precise optimization and variability reduction among FBS lots. We investigated ES-sac generation using VEGF by comparing 15%FBS-based media (Control) and serum-free 20%KSR-based media (MEF-KSR) on C3H feeder cells using H1 hESCs (maintained on MEF feeder cells). In addition, we compared feeder-free hESCs (maintained on Matrigel) with on-feeder hESCs using both KSR-based media (MT-KSR) and FBS-based media (MT-FBS) to determine whether feeder-free hESCs culture produces a more uniform cell population. 15 days after ES-sac generation, hematopoietic-like suspension cells were differentiated to erythroid cells with erythropoietin for an additional 15 days (total 30 days). After ES-sac generation (day 15), we counted ES-sac numbers (from 1x10e5 hESCs), and analyzed definitive hematopoietic precursor cells (HPCs, CD34+CD45+), erythromegakaryocyte precursors (EMPs, CD235a+CD41a+), and primitive erythrocytes (PEs; CD235a+CD34-) by flow cytometry. After erythroid differentiation (day 30), we evaluated erythroid cell yields (from 1x10e5 hESCs) and globin protein levels by HPLC.We observed similar amounts of ES-sacs (62±48 vs 40±30, ns) at day 15 and erythroid cell yields (32±19 vs 41±12 x10e5, ns) at day 30 as well as similar levels of β-globin (13±10 vs 19±9%, ns) and ε-globin (21±10 vs 12±4%, ns) between MEF-KSR and Control. The MEF-KSR results in similar percentages of HPCs (4±2 vs 7±5%, ns), EMPs (9±6 vs 14±14%, ns), and PEs (25±11 vs 36±13%, ns) in ES-sacs, suggesting that KSR can replace FBS allowing for similar ES-sac generation with erythroid differentiation derived from on-feeder hESCs.When using feeder-free hESCs, ~10-fold greater amounts of ES-sacs (564±458 and 208±138 vs 40±30) and erythroid cell yields (180±134, p<0.01 and 71±6 vs 41±12 x10e5) were obtained in MT-KSR (p<0.01) but not MT-FBS (ns), compared to Control (Figure). Lower percentages of HPCs (2±2, p<0.01 and 6±4, ns vs 7±5%), EMPs (7±4 and 7±2 vs 14±14%, ns), and PEs (22±10 and 20±3 vs 36±13%, p<0.05) were observed in MT-KSR and MT-FBS, while high levels of β-globin (23±5 and 23±4 vs 19±9%, ns) and low levels of ε-globin (14±5 and 8±3 vs 12±4%, ns) were detected at similar protein levels among all groups (Figure). These data demonstrate that our serum-free culture (MT-KSR) allows for greater amounts of ES-sac generation, resulting in more erythroid cell yields with high β-globin production.To evaluate whether KSR-based media improve ES-sac colony formation in the initial step or ES-sac structure production in the maturation step, we investigated either KSR- or FBS-based media in the first half and second half of ES-sac generation from feeder-free hESCs: switched from KSR to FBS (KSR-FBS) or FBS to KSR (FBS-KSR), as compared to Control (FBS-based media only). We observed a trend to higher amounts of ES-sac generation (157±74 and 88±16 vs 48±20, ns), lower percentage of HPCs (1±1, p<0.05 and 6±1, ns vs 4±2%), higher percentage of EMPs (10±2, p<0.05 and 1±1, ns vs 5±1%), and higher percentage of PEs (27±7, p<0.01 and 8±2, ns vs 16±1%,) were observed in KSR-FBS (similar to KSR only) but not in FBS-KSR (similar to FBS only). These data suggest that KSR-based media allows for improved ES-sac colony formation in the initial step, while FBS may increase emergence of definitive hematopoietic precursors during ES-sac generation.In summary, we demonstrate improved ES-sac colony formation with serum-free culture from feeder-free hESCs producing erythroid cell yields with high β-globin production (up to 23%) detectable at the protein level. Further improvement of hESC-derived erythroid cell generation might be achieved by additional nutrients or cytokines in defined KSR-based media. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Uniform Stepped Interfacial Energy Level Structure Boosts Efficiency and Stability of CsPbI2Br Solar Cells

AbstractAll‐inorganic CsPbI2Br perovskite has attracted great attention as an absorber for perovskite solar cells (PSCs) due to its excellent thermal and light resistance. However, its device performance is restricted by the large energy level offset between CsPbI2Br and the most commonly used hole‐transporting layer (HTL). Herein, multicarbazolyl‐substituted benzonitrile (4t‐5CzBn) is inserted into the interface between CsPbI2Br and HTL to form a uniform stepped (0.24 eV) interfacial energy level structure, which reduces the energy loss and boosts the hole extraction of CsPbI2Br PSCs. The incorporation of 4t‐5CzBn induces the increase in open‐circuit voltage and fill factor from 1.256 V and 74.5% to 1.335 V and 82.3%, respectively. The optimized device achieves a power conversion efficiency of 17.34%, which is among the highest reported values of CsPbI2Br PSCs. Besides the energy level tuning effect, the tert‐butyl groups in 4t‐5CzBn improve the moisture‐resistance of CsPbI2Br PSCs. The unencapsulated device maintains over 75% of its initial efficiency after 700 h storage in air. These results demonstrate that the rational tuned energy level step benefits the performance improvement of CsPbI2Br PSCs.

Insight into the Influence of Mineralogical Properties of Pristine Pyrite on Its Bioleaching with Thermophiles

ABSTRACT To expound the relationship between bioleaching behaviors and mineralogical properties of pristine pyrite samples, chemical compositions, semiconductive properties, surface morphologies, and chemical species of synsedimentary pyrite (SSP) and mesothermal pyrite (MTP) were compared, accompanying with bioleaching behaviors analysis by three thermophiles. Mineralogical characterizations showed that both pyrites belonged to p-type semiconductors with an S/Fe ratio higher than 2, and the arsenic content in MTP was as high as 0.6%. The fractured surface of SSP had more kinks and steps, and higher concentrations of S2- and oxides, as compared with that of MTP. Bioleaching results indicated that SSP was leached faster than MTP. The more kinked and stepped structures and the larger contents of S2- and oxides on pyrite surfaces were the dominant reasons for the faster bioleaching kinetics of SSP. The high arsenic content in MTP limiting the cell growth was another cause for its slower leaching.

Determination of steep sidewall angle using polarization-sensitive asymmetric scattering

The sidewall angle (SWA) of a nanostructure exerts influence on the performance of the nanostructure and plays an important role in processing nano-structural chips. It is still a great challenge to determine steep SWAs from far field measurements especially when the SWAs are close to 90°. Here, we propose a far-field detection system to determine steep SWA of a cliff-shape step structure on a silicon substrate by combining a split detector with a scanning method. The far-field radiation field is asymmetric due to the scattering of the step structure, and further numerical analysis demonstrates the reliability of this far-field measurement method. In the simulations, two key variables, i.e. the polarization state and the focus position of the incident laser beam, are considered to explore their impacts. By scanning over the structure laterally and longitudinally with both TE and TM polarizations, polarization effects on the far-field occur. These effects show higher sensitivity to steep SWA variation for TM polarization as compared to TE. Furthermore, with a comprehensive longitudinal scanning analysis for the TM polarization case, a feasible focus interval can be optimized to retrieve the steep SWA. As the proposed method is fast, highly sensitive and easy to implement, it provides a powerful approach to investigate the scattering behavior of nanostructures.

3-D Printed All-Dielectric Dual-Band Broadband Reflectarray With a Large Frequency Ratio

This communication proposes a new all-dielectric broadband dual-band reflectarray with a large frequency ratio using low-cost 3-D printing. In contrast to conventional reflectarrays using metallic resonant cells or dielectric slabs as phasing elements with full metal ground, the proposed design uses air as the phasing element and a stepped dielectric mirror structure as the ground. In this way, the metal ground is removed, which makes the design an all-dielectric one. Taking advantage of the dielectric mirror that only exhibits a bandgap in the predesigned band while allowing electromagnetic (EM) waves to pass through it at the frequency out of the bandgap region, a dual-band reflectarray is obtained. By properly selecting the bandgap frequency of the dielectric mirror, the dual-band frequency ratio is scalable and can be very large. Furthermore, instead of using a metallic or dielectric resonator based on resonance, air layers with linear phase response are adopted as the phasing element. Thus, the reflectarray shows broadband and stable performance over the dual-band. Compared with the state-of-the-art works using printed circuit boards (PCBs) or microfabrication, the proposed design is low cost and lightweight, and can be rapidly prototyped. For proof-of-concept, a prototype operating at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -band and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> -band with a frequency ratio of 2.7 is printed and measured.

Design, simulation and analysis of uniform and non-uniform serpentine step structure RF MEMS switch

Design, simulation and analysis of uniform and non-uniform serpentine step structure RF MEMS switch

Engineering superhydrophilic/superaerophobic hierarchical structures of Co-CH@NiFe-LDH/NF to boost the oxygen evolution reaction

3D superhydrophilic/superaerophobic hierarchical “rod-sheet” structure of NiFe-based layered double hydroxides coupled with cobalt carbonate hydroxide (Co-CH@NiFe-LDH/NF) has been synthesized on Ni foam by a Fe3+ ion hydrolysis-induced etching-growth approach under hydrothermal conditions. The Co-CH@NiFe-LDH/NF electrode demonstrates excellent oxygen evolution reaction (OER) performances, which mainly result from the synergic effect between Co-CH and NiFe-LDH. The unique stepped hierarchical “rod-sheet” structure of Co-CH@NiFe-LDH/NF not only benefits the inherent catalytic activity, but also enhances the electron transfer and increases the exposed active sites. Moreover, the superhydrophilic/superaerophobic joint properties of Co-CH@NiFe-LDH/NF promote the diffusion of aqueous electrolyte and ensure the rapid release of bubbles. Furthermore, a water-splitting device has been assembled with commercial Pt/C/NF and Co-CH@NiFe-LDH/NF as cathode and anode, respectively, which can work stably for 200 h without obvious degradation. Hence, the strategy of engineering stepped hierarchical structures with synergistic effect may offer a new pathway to synthesizing highly efficient OER electrocatalysts.

Low terahertz-band scanning near-field microscope with 155-nm resolution

We report on the design and implementation of a scattering-type scanning near-field microscope working in the low terahertz-band under ambient conditions for nanoscopic investigations of physical properties and characteristics at sample surfaces and interfaces in the microwave and millimeter wave bands. Employing a nano-tip that oscillates vertically at a frequency Ω as the antenna, and a subharmonic mixer as the receiver, and corresponding demodulation algorithms, the back-scattered light carrying tip-sample interaction information is effectively extracted, while excluding almost all of the background noises. The amplitude and phase images constructed from signals demodulated at various harmonics (nΩ, n = 1 - 4) are obtained while scanning an Au-Si step structure with the newly developed microscope, and a resolution of 155 nm (~λ/20,000) has been demonstrated at the fourth harmonic frequency (4Ω) working at 110 GHz, with signal-to-noise ratio (SNR) equal to 44.4 dB on the Au surface and 36.2 dB on the Si surface, demonstrating the power of this new instrument for micro/nano-resolution studies in the millimeter wave band.

Microprismatic Fresnel Lens for Formation of Uniform Light Circle

Focusing Fresnel lenses are used in many fields of applied optics. These devices are used in optical sensor systems for imaging and optoelectronic integration. The traditional Fresnel lens concentrates the light intensity on the center of the formed image. We present a microprismatic Fresnel lens that transforms a circular incident parallel light beam into a homogeneous light circle with the necessary diameter at a certain distance from the lens. These transforming Fresnel concentrators can be successfully used, for example, in monitoring devices to automatically adjust the output signal from four-quadrant photodetectors. Traditional focusing Fresnel structures are manufactured by photolithographic methods or adjustable direct laser recording with photoresists. These methods enable the formation of stepped optical structures, which have inherent surface defects, resulting in the formation of images that are not high in quality. The proposed specialized Fresnel concentrators can be easily fabricated via the diamond cutting method, which enables the manufacturing of flat working surfaces with exceedingly high optical quality. We also develop a method for simulating the Fresnel transforming lenses with flat conical working facets and calculate the geometric parameters of the circular concentrators. We then apply the simulation results to the diamond cutting method and fabricate the microprismatic light transforming lens samples. These samples are then investigated experimentally with a collimated laser beam. The obtained data agree with the theoretical predictions.

Theoretical and experimental study of bulge formation in laser polishing of 304 stainless steel

Abstract As an emerging surface treatment process, laser polishing is dedicated to reducing the surface roughness of the sample, but some new surface structures (such as ripples, undercuts, bulges, step structures, and martensite needles) may be introduced into the polished surface, affecting the effect of laser polishing. This work aims to reveal the formation mechanism of bulges in the center of the polished track. The effect of laser polishing process parameters on the size parameters of bulges was studied through experiments of laser polishing. And a two-dimensional numerical model was developed by coupling heat transfer and fluid flow. The evolution of bulges, the temperature field, and the velocity field was presented with this model. Furthermore, through the analysis of the surface forces and surface velocities of the molten pool, it was found that the thermocapillary force affected by surface-active elements (oxygen, sulfur, and phosphorus) is the main driving force for the formation of bulges. And some measures to reduce or eliminate bulges were proposed to improve the surface finish of laser polishing. In addition, the final surface profile of the bulges after laser polishing was simulated, which was in good agreement with the experimental results. And this model can be extended to predict the evolution of surface topography in laser polishing, guiding the optimization of process parameters in laser polishing.

Строение древостоев северотаежных сосняков

In Northern taiga conditions pine forests occupy about 1.8 mln ha of the territory of the Komi Republic and are mainly represented by sphagnum, green-moss and lichen forest types. The studies were carried out at the Zelenoborsk Forest Station of the Institute of Biology of the Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences in green-moss and sphagnum pine forests developing at the site of fires and clearcuts. Tree layer has a mix composition with the predominance of pine trees and admixture of spruce, birch, larch and aspen. Pine stands form three types of age structure: conventionally evenaged; conventionally uneven-aged, represented by one generation; and stepped uneven-aged, consisting of two or three generations of pine trees. Trees left behind during clearcut and felling residuals at the cutting area by the burn method contribute to the formation of stands of stepped uneven-aged age structure. The variation coefficients of tree age are 5.8–10.8 % in pine forests with one generation and 39.7–45.6 % in forests with two or three generations. The number of generations and the type of age structure had no effect on the diameter and height of trees in the stand, which varied respectively within 25.2–49.5 % and 15.7–27.8 %. In pine forests developing after fires, the peak of pine settlement occur in the second or third decade, while in cutting areas, the maximum renewal occurs in the first or second decade after clearcuts. The amplitude of tree age fluctuations varies from 16 to 33 years in conventionally even-aged and conventionally uneven-aged forests developed after clearcuts and from 30 to 45 years in post-fire stands. In stepped uneven-aged stands tree age fluctuations changes from 120 to 167 years, and from 22 to 66 years in generations. The curves showing the distribution of trees by diameter in stands of pine trees had a left-handed shift, the asymmetry is represented by positive values and varies from 0.05 to 1.03. Trees of associate species are inferior in development, both in diameter and in height to pine trees of similar age. A close correlation between the diameter and height of trees in the stands was revealed. The relationship of age with diameter and height of trees varies from weak to significant at almost all of the sites studied. A close correlation between age and diameter was found in stepped uneven-aged pine forests (R = 0.79–0.96). The correlation between diameter and age increase with an increase in tree age fluctuations amplitude.

Effect analysis of surface metal layer on step height standard

In order to improve the measurement accuracy of the step height measuring instrument, a semiconductor process was used to prepare the step height standard for calibrating the instrument. Aiming at the problem of deviation in the white light interferometer measuring step height standard, the cause of the measurement deviation was theoretically analyzed, combining the optical theory and the principle of instrument. In addition, referring to the semiconductor sputtering process, a method of sputtering metal layer on the surface of the step structure was proposed, and a set of universal step height standards with a nominal value of [Formula: see text] nm were developed for the step height measuring instrument. Finally, the step height standards with the sputtered metal layer were compared and measured, using the white light interferometer and nanometer measuring machine (NMM). The measurement error of the white light interferometer can be effectively controlled within 1%, which is beneficial to verify the measurement capability of the step height measuring instrument.

Charge-Transfer Steps in Density Functional Theory from the Perspective of the Exact Electron Factorization.

When a molecule dissociates, the exact Kohn-Sham (KS) and Pauli potentials may form step structures. Reproducing these steps correctly is central for the description of dissociation and charge-transfer processes in density functional theory (DFT): The steps align the KS eigenvalues of the dissociating subsystems relative to each other and determine where electrons localize. While the step height can be calculated from the asymptotic behavior of the KS orbitals, this provides limited insight into what causes the steps. We give an explanation of the steps with an exact mapping of the many-electron problem to a one-electron problem, the exact electron factorization (EEF). The potentials appearing in the EEF have a clear physical meaning that translates to the DFT potentials by replacing the interacting many-electron system with the KS system. With a simple model of a diatomic, we illustrate that the steps are a consequence of spatial electron entanglement and are the result of a charge transfer. From this mechanism, the step height can immediately be deduced. Moreover, two methods to approximately reproduce the potentials during dissociation are proposed. One is based on the states of the dissociated system, while the other one is based on an analogy to the Born-Oppenheimer treatment of a molecule. The latter method also shows that the steps connect adiabatic potential energy surfaces. The view of DFT from the EEF thus provides a better understanding of how many-electron effects are encoded in a one-electron theory and how they can be modeled.

Continuous synthesis of star polymers with RAFT polymerization in cascade microreactor systems

With the RAFT arm-first method, butyl acrylate and 4-acryloylmorpholine were used as monomers to form linear arms, which subsequently reacted with the cross-linker 1,6-hexanediol diacrylate to form star-shaped macromolecules in cascade microreactor systems. After studying polymerization kinetics in each step, homoarm and miktoarm star products with various arm compositions were steadily prepared by optimizing the reaction flowsheet and adjusting the reactant formula. Such continuous-flow processing avoided tedious intermediate purification procedures and prepared polymer products with considerable star yield (>70%), molecular weights (Mw,LS > 100 kg/mol) and arm numbers (>30). Multiple emulsions (including two types, i.e., oil-in-water and water-in-oil) were formed utilizing star products with different amphiphilic architectures as emulsifiers. This study demonstrated that in this continuous-flow mode, through regulating the residence time and flow rate ratio in each step, the arm and core structures of star polymers were tailored to possess remarkable functional applications.

Comparative study of base-isolated irregular RC structures subjected to pulse-like ground motions with low and high PGA/PGV ratios

Nowadays, vertically irregular reinforced concrete structures are very commonly seen in modern urban construction. These structures are of high vulnerability to lateral seismic shaking intensities as compared to regular buildings due to their inconsistent stiffness distribution along with the height. In general, the utilization of a base isolation system in a reinforced concrete building is considered an effective solution for seismic mitigation in earthquake-prone countries. The behavior of these buildings in both regular and irregular cases has been extensively studied in the literature. Moreover, the performance of the base isolated buildings under pulse-like earthquakes has attracted several researchers through the previous years due to the significant influence of such ground motions on the displacement stability of the isolation system. Currently, the literature is missing a study that evaluates and compares the full nonlinear time history behavior of different irregular reinforced concrete structures under near-fault pulse-like ground motions. Therefore, this study is intended to investigate the time history behavior of various base isolated reinforced concrete models subjected to pulse-like earthquakes with low and high PGA/PGV ratios. As a part of the study, the responses of heavy-story, soft-story, and stepped structures will be compared to the ones of a regular model. Furthermore, the effects of three different isolator’s effective damping ratios on the time history responses will be evaluated. The results of the study showed that the behavior of the isolator is influenced by the building irregularity type and the PGA/PGV ratio significantly.

Improvement of Critical Current in Superconducting Joint Between Multi-Filamentary Bi2223 Tapes

The superconducting joint between Bi2223 tapes has been developed with a method of joint by incongruent melting (JIM) in our Laboratory. The multi-junction method used to increase the contact area yielded a demonstrated increase in critical current. In previous studies, a simple boundary shape with lap-joint was chosen to connect several filaments in the tape, and this method is not suitable for connecting all about 100 filaments. Of course, more filaments are necessary to be joined with superconducting boundary, in order to increase the critical current of joint. However, due to the thin tape structure, there is difficult to use of butt joint between two cross-sections of tapes. In this study, we proposed a multi-junction method by using multiple boundaries with stepped structure. In experiments, joint samples with increasing of junction number to three from one were prepared, and the critical current for each unction number were measured at 77 K (self-magnetic field). In result, the critical current is increased with increasing of the junction number, and a highest critical current of 51.8 A was obtained in three-junction sample. in particular, the critical current at first junction (end of tapes) is highest, indicating that critical current at the end is important in total critical current of joint. Therefore, single junction at end of tapes was prepared and evaluated by using X-ray diffraction and critical current measurement. From X-ray diffraction patterns, the joint area is estimated to be about 1 cm. The critical current was 36.5 A at 77 K.

From Kohn-Sham to Many-Electron Energies via Step Structures in the Exchange-Correlation Potential.

Accurately describing excited states within Kohn–Sham (KS) density functional theory (DFT), particularly those which induce ionization and charge transfer, remains a great challenge. Common exchange-correlation (xc) approximations are unreliable for excited states owing, in part, to the absence of a derivative discontinuity in the xc energy (Δ), which relates a many-electron energy difference to the corresponding KS energy difference. We demonstrate, analytically and numerically, how the relationship between KS and many-electron energies leads to the step structures observed in the exact xc potential in four scenarios: electron addition, molecular dissociation, excitation of a finite system, and charge transfer. We further show that steps in the potential can be obtained also with common xc approximations, as simple as the LDA, when addressed from the ensemble perspective. The article therefore highlights how capturing the relationship between KS and many-electron energies with advanced xc approximations is crucial for accurately calculating excitations, as well as the ground-state density and energy of systems which consist of distinct subsystems.

Fast prediction of the shielding effectiveness and resonances of the heterotypic metallic enclosure with a built-in dielectric plate

On the basis of the characteristics of the heterotypic metallic enclosure with a built-in dielectric plate, this paper proposes an analytical method to evaluate the shielding performance of an apertured enclosure with convex or stepped structure under the plane wave illumination. First, the heterotypic enclosure is modeled based on the electromagnetic topology (EMT) theory, where the scattering parameter matrix at the discontinuous position can be derived according to the theory of microwave circuit. Then, the expressions of total voltage components can be obtained by using the extended Baum-Liu-Tesche (BLT) equation, which are convenient to calculate the SE at the monitor point. Finally, the effectiveness and accuracy of the proposed method in predicting the shielding effectiveness (SE) and resonances of heterotypic enclosure are verified by the computer simulation technology (CST) through several cases. Compared with the CST simulation, the proposed method is more efficient and takes up less memory.