Space Mapping Technique Research Articles

Experimental and Theoretical Study of the Triple-Crystal High-Resolution X-Ray Diffraction Scheme in Reciprocal Space Mapping Technique

The triple-crystal high-resolution X-ray diffraction scheme has been experimentally and theoretically investigated using reciprocal space mapping. The procedure for calculating the spectral angular instrumental functions of diffractometer to take into account the influence of mirror, monochromator, analyzer, and slits on the intensity distribution near reciprocal lattice point is described. Good coincidence of calculated and experimental cross sections of reciprocal space maps (RSMs) is shown by an example of a perfect Si(110) single crystal.

Fast Design of Multilayered Shields Using Surrogate Model and Space Mapping

Designing an efficient shield using simulation requires an expansive computational cost due to large ratio of width to thickness. This paper presents a two-level surrogate based optimization process to efficiently design multilayered shields. The method first exploits space-filling sampling to obtain a global optimal start point. The coarse model is then adopted to be the first-level surrogate. Two-dimensional (2-D) simulation is selected as the coarse model to avoid the time consuming high-fidelity 3-D calculation. Sequential design is followed where response surface approximation (RSA) is applied to construct the surrogate of the coarse model. The evaluation time of the RSA is negligible and it is the second-level surrogate. Finally, the optimum design found by the surrogate is refined using space mapping technique to give an approximation of the location of the optimum design of the original problem. By taking advantages of both surrogate modeling and space mapping, the proposed approach can significantly improve the efficiency of the design process. The method is applied to optimize a double shield and a U-shaped double shield to show its efficiency.

Proposal of a Bi-Objective Kriging Adapted Output Space Mapping Technique for Electromagnetic Design Optimization

Multi-objective optimization with finite-element model (FEM) for the optimal design of electromagnetic devices is a complex task and also time costly. Output space mapping (OSM) techniques allow having an affordable computation cost with a minimum number of computationally expensive FEM evaluations. In this paper, a bi-objective Kriging adapted OSM, an original space-mapping technique based on adaptive nonlinear corrective projection, is proposed. First, the proposed technique is validated using a mathematical test function; Second, it is applied on a three-phase brushless dc motor, which is represented through two modeling levels: 1) coarse (analytical model) and 2) fine (2-D FEM). An advantage of this new technique is its ability to make the coarse model converge effectively toward the fine model.

Shear strain-induced anisotropic domain evolution in mixed-phase BiFeO3 epitaxial films

Understanding and controlling the domain evolution under external stimuli in multiferroic thin films is critical to realizing nanoelectronic devices, including for non-volatile memory, data storage, sensors, and optoelectronics. In this article, we studied the shear-strain effect on the domain evolution with temperature in highly strained BiFeO3 thin films on rhombohedral LaAlO3 substrates using a high-resolution synchrotron X-ray diffraction three dimensional-reciprocal space mapping (3D-RSM) technique. The results revealed significant biaxial, anisotropic, evolution behaviors of the mixed-phase (MC + R′/T′ phases) BiFeO3 ferroelectric domains along the in-plane [100] and [010] axes. These biaxial, anisotropic, evolution behaviors were attributed to the shear-strain-modulated transition pathways of the mixed-phase ferroelectric domains. This viewpoint was further verified in the BiFeO3/LaSrAlO4 (001) system in which no anisotropic evolution behaviors of the mixed-phase domains were found. This work sheds light on the quantitative analysis of domain evolution in multi-domain systems and demonstrates that the shear-strain effect could act as an effective tool to manipulate the domain behavior and control novel functionalities of ferroelectric thin films.

Time-resolved X-ray reciprocal space mapping of a crystal in an external electric field

A reciprocal space mapping technique with the use of triple-crystal time-resolved X-ray diffractometry has been developed and implemented using a laboratory X-ray source for the first time. This technique allows studying fast processes that occur in a sample under external influences that cause reversible deformations of its crystal lattice. It also allows distinguishing these processes in time and distinguishing different types of crystal deformations caused by these actions. The essence of the technique is to measure time dependences of the intensity for each point of the reciprocal space in the vicinity of the diffraction maximum in three-axis diffraction geometry by subjecting the sample to repeated and structurally identical action of a strong electric field, with the subsequent construction of the time evolution of the two-dimensional reciprocal space map. The time resolution is achieved with the use of a high-speed multichannel intensity analyzer synchronized with a high-voltage source. The results of measuring the reciprocal space maps with a laboratory radiation source with a time resolution of up to 10 ms are demonstrated for a piezoelectric crystal of lanthanum gallium silicate subjected to an external electric field with the field strength 3.08 kV mm−1, which is close to the sample breakdown value.

Digital-controlled six-channel switched dielectric filter bank of L-band

ABSTRACTThis paper introduces a design of a digital-controlled, six-channel, switched dielectric filter bank of L-band. The physical parameters of a monoblock dielectric filter are optimized by an aggressive space mapping technique. Two HMC252Q24 switches are used for single-pole six throws (SP6T) to realize a 3-bit digital-controlled filter bank. And six filters made of dielectric ceramics are used having advantages of small size and low insertion loss. These six filters and two switches are then fabricated on printed circuit board and measured under 3-bit transistor-transistor logic (TTL) signals. The measured results have shown that (i) 3-bit TTL signals control the path of the filter bank, (ii) six states correspond to six filters and two states are off, and (iii) the isolation between filters exceeds more than 45 dB.

Laser frequency offset-locking using electromagnetically induced transparency spectroscopy of 85Rb in magnetic field**Project supported by the National Key Basic Research Program of China (Grant No. 2013CB922003) and the National Natural Science Foundation of China (Grant Nos. 91421305, 91121005, and 11174329).

We have experimentally offset-locked the frequencies of two lasers using electromagnetically induced transparency (EIT) spectroscopy of 85Rb vapor with a buffer gas in a magnetic field at room temperature. The magnetic field is generated by a permanent magnet mounted on a translation stage and its field magnitude can be varied by adjusting the distance between the magnet and Rb cell, which maps the laser locking frequency to the space position of the magnet. This frequency–space mapping technique provides an unambiguous daily laser frequency detuning operation with high accuracy. A repeatability of less than 0.5 MHz is achieved with the locking frequency detuned up to 184 MHz when the magnetic field varies from 0 up to 80 G.

Impact of an InxGa1–xAs Capping Layer in Impeding Indium Desorption from Vertically Coupled InAs/GaAs Quantum Dot Interfaces

This study describes the effect of a thin GaAs spacer of 4.5 nm thickness in a bilayer-coupled InAs quantum dot (QD) heterostructure. Here, we report the first demonstration of InAs/GaAs QDs capped by self-assembled InxGa1–xAs layers. Self-assembled InxGa1–xAs layers were introduced into each intermediate layer across the interface of InAs QDs and the GaAs layer in a vertical-coupled bilayer QD (VCBQD) heterostructure to prevent indium desorption from the QDs. A change in the indium content in the seed-layer InAs QDs changes the self-assembly position and modifies the InxGa1–xAs layer thickness. A theoretical approach was presented to study the formation of self-assembled InxGa1–xAs layers at each strain-free layer. We showed that the strain energy at the second intermediate (εzz2) layer is greater than that at the first intermediate (εzz1) layer; εzz2 depends on the vertical strain channel length. The impact of the InxGa1–xAs layer thickness on the strain energy was studied using high-resolution transmission electron microscopy; a shorter strain channel length was found to facilitate the formation of a more relaxed and larger-sized self-assembled InxGa1–xAs layer in the active layer. This InxGa1–xAs layer formed at the intermediate layer acts as a capping layer or a protective shield for the indium adatoms, preventing their desorption from the InAs QDs. Furthermore, we studied the thermal stability of the self-assembled InxGa1–xAs layer by annealing the VCBQD samples at 700 and 800 °C. This aspect has been investigated for the first time ever in a study of the coupling efficiency between the InAs QDs and InxGa1–xAs capping layer. A high-resolution in-plane (2θχ/ϕ) reciprocal space mapping (RSM) technique provided the connection between the in-plane reciprocal lattice point of the InAs QDs and InxGa1–xAs layers and revealed the strain and coupling between them. InAs QDs fully covered with the self-assembled InxGa1–xAs layer enhanced the photoluminescence intensity by 77% and had an activation energy of 467 meV.

Space Mapping Approach to Electromagnetic Centric Multiphysics Parametric Modeling of Microwave Components

This paper proposes a novel technique to develop a low-cost electromagnetic (EM) centric multiphysics parametric model for microwave components. In the proposed method, we use space mapping techniques to combine the computational efficiency of EM single physics (EM only) simulation with the accuracy of the multiphysics simulation. The EM responses with respect to different values of geometrical parameters in nondeformed structures without considering other physics domains are regarded as coarse model. The coarse model is developed using the parametric modeling methods such as artificial neural networks or neuro-transfer function techniques. The EM responses with geometrical and nongeometrical design parameters as variables in the practical deformed structures due to thermal and structural mechanical stress factors are regarded as fine model. The fine model represents the behavior of EM centric multiphysics responses. The proposed model includes the EM domain coarse model and two mapping neural networks to map the EM domain (single physics) to the multiphysics domain. Our proposed technique can achieve good accuracy for multiphysics parametric modeling with fewer multiphysics training data and less computational cost. After the modeling process, the proposed model can be used to provide accurate and fast prediction of EM centric multiphysics responses of microwave components with respect to the changes of design parameters within the training ranges. The proposed technique is illustrated by a tunable four-pole waveguide filter example at 10.5–11.5 GHz and an iris coupled microwave cavity filter example at 690–720 MHz.

Comparison of three space mapping techniques on electromagnetic design optimization

PurposeThis paper aims to investigate three low-evaluation-budget optimization techniques: output space mapping (OSM), manifold mapping (MM) and Kriging-OSM. Kriging-OSM is an original approach having high-order mapping.Design/methodology/approachThe electromagnetic device to be optimally sized is a five-phase linear induction motor, represented through two levels of modeling: coarse (Kriging model) and fine.The optimization comparison of the three techniques on the five-phase linear induction motor is discussed.FindingsThe optimization results show that the OSM takes more time and iteration to converge the optimal solution compared to MM and Kriging-OSM. This is mainly because of the poor quality of the initial Kriging model. In the case of a high-quality coarse model, the OSM technique would show its domination over the other two techniques. In the case of poor quality of coarse model, MM and Kriging-OSM techniques are more efficient to converge to the accurate optimum.Originality/valueKriging-OSM is an original approach having high-order mapping. An advantage of this new technique consists in its capability of providing a sufficiently accurate model for each objective and constraint function and makes the coarse model converge toward the fine model more effectively.

Revitalizing the unused urban space, case study: Lhokseumawe, Aceh -Indonesia

The phenomenon of urban decline in the highly industrialized nation is now slowly taking place in the developing world. Deindustrialization as defined as a decline in the manufacturing sectors led to the changes in social, economic and subsequently a shift in urban activities. By taking Lhokseumawe, Aceh, Republic of Indonesia as an example, this paper attempts to uncover the possibilities and opportunities in identifying the causes and tracing back on the decline. Lhokseumawe, Aceh was a well-known industrial region outside Java Island, and it has attracted thousands of workers from northern Sumatera and the nearby regions. After the downturn of the economy and the change in activities, the city slowly showed a decline. Scholars has estimated that one in six of the cities around the world that relied on oil and gas production activities will suffer from this phenomenological impact. Lhokseumawe is a good example of an industrial plants where PT Arun LNG (private limited company) operated since 1974 grew up rapidly and nicknamed “Petrodollar City”. The trickle effect of the activities from the petrodollar business led to a few settlements popping up at the periphery as a result of urban sprawl from Lhokseumawe, however, the glory of the economic growth outlived within a short period. This was resulted from the production of PT Arun NGL which had dropped dramatically in the 2000s and suddenly closed the operation in October 2014. From these perspectives, this paper attempts to investigate the impact of deindustrialization within the urban space and activity in Lhokseumawe which have consequences to urban declining phenomena. By taking one of the revitalized urban space formerly known as Cunda Plaza (CP) as a case study area, the paper will apply synoptic method through observation, space mapping and interview techniques for gathering and examining the data. The findings indicates that Cunda Plaza is a magnet as a central hub of urban activities which can be integrated with other thriving activities from urban conurbation of academic related activities within the city.

Infinitesimal Dipole Model Using Space Mapping Optimization for Antenna Placement

The infinitesimal dipole model (IDM) is very appealing for antenna placement problems, especially since antenna design details need not be available. The method has been mainly used to model antennas radiating in free space or above an infinite perfectly conducting ground plane, with synthetic data. The direct application of the method considering finite ground planes is impracticable because of the complexity of the associated Green's functions. In this letter, we propose a methodology to devise the equivalent model, taking into account edge diffraction effects due to the finite ground plane, but still maintaining a relatively low computational cost. We combine the classical IDM with the output space mapping technique so that the burden of model optimization is placed on the analytical model, and the more accurate but computationally intensive model is evaluated only a few times. To demonstrate the applicability of the method, we model a radar altimeter antenna operating at 4.3 GHz in a typical case of antenna integration: Only the measured far-field data are available. The equivalent model obtained is then incorporated into a commercial electromagnetic simulation package to compare its installed radiation pattern with the actual antenna measured pattern. An excellent agreement is verified.

Design and Optimization of SIW Center-Fed Series Rectangular Dielectric Resonator Antenna Array With 45° Linear Polarization

The modeling, design, and optimization of a new substrate integrated waveguide middle-fed series rectangular dielectric resonator antenna array with 45° linear polarization are presented. The implicit space mapping technique is applied for the optimization of the antenna array. A tunable circuit model is built, which serves as the coarse/surrogate mode, and a full-wave solver is used as the fine model. High design and optimization efficiency is demonstrated using an eight-element array. The reflection coefficient of the array antenna is optimized with only two iterations. The experimental data for the eight elements antenna array, operating at the millimeter-wave band (34–36 GHz), are used for the validation of both performance of the design and modeling techniques. The measured radiation pattern demonstrates a broadside beam with a maximum radiated gain of 13.55 dB over an operating impedance bandwidth of 2.2 GHz.

Optimization of IC-Stripline Performance by Response Surface Space-Mapping Technique

This paper presents the design optimization of the closed version of the IC-Stripline. The geometrical parameters of the IC-Stripline are optimized in order to improve the voltage standing wave ratio (VSWR). Time-consuming direct optimization by three-dimensional electromagnetic (3-D EM) simulations is avoided by implementation of the response surface space-mapping technique. The implemented technique sequentially builds up the response surface model according to the results obtained from the new iterations of the 3-D EM simulation. Based on 3-D EM simulation results the parameters of the equivalent circuit model are extracted. The extracted parameter values form the response surface that is modeled by the radial basis functions. The search for the optimal design point is performed by the design space exploration (Voronoi tessellation algorithm) and the problem exploitation (gradient method optimization of the response surface models). The presented technique results in efficient optimization performed in a small number of iterations. The IC-Stripline is manufactured according to the presented optimization results and VSWR less than 1.25 in the frequency range up to 4.4 GHz is obtained.

Proposal of a Kriging Output Space Mapping Technique for Electromagnetic Design Optimization

Using the finite-element model (FEM) to achieve the optimal design of electromagnetic devices is a complex and time-consuming process. Space-mapping techniques reduce computation cost by aligning two models with different granularities, namely, a coarse model and a fine model. In this paper, Kriging output space mapping (OSM), an original space-mapping technique based on adaptive nonlinear corrective projection, is proposed and compared with a conventional OSM technique. The device for optimal sizing is a five-phase linear induction motor, which is represented through two modeling levels: 1) coarse (Kriging model) and 2) fine (2-D FEM). An advantage of this new technique is its ability to provide a sufficiently accurate model for each objective and constraint function and make the coarse model converge effectively toward the fine model.

Space mapping techniques for the optimal inflow control of transmission lines

In this paper we present an efficient optimization approach for the dynamic inflow control of electric transmission lines. For the description of transmission lines several mathematical models are available. Here, we focus on the telegraph network equations which consist of a coupled system of hyperbolic differential equations. The optimization is then to find the best possible energy input in terms of boundary control to satisfy given demands. To solve this problem we introduce space mapping techniques based on a first discretize – then optimize approach. The idea of space mapping is the consideration of two model hierarchies (fine and coarse scale), where the coarse scale model is less accurate but easy to solve. We explain how this method works in the framework of inflow control, design the corresponding optimization algorithm and present various computational results to show the numerical efficiency.

An advanced analytical neuro–space mapping technique with sensitivity analysis for transistor modeling

AbstractThis paper presents an advanced analytical neuro–space mapping (neuro‐SM) technique for accurate and efficient modeling of transistor devices. This is an improvement over the existing neuro‐SM, which aims to use neural networks to map a given approximate device model towards an accurate model. The proposed neuro‐SM retains the ability of the existing neuro‐SM in modifying the voltage relationship between the given approximate device model and the accurate model. The proposed technique can also map the current relationship between the given model and the accurate model. In this way, the proposed neuro‐SM can produce improved accuracy over the existing neuro‐SM. In addition, analytical formulas of mapping and sensitivities of the direct current, small‐signal S parameter, and large‐signal harmonic of the proposed neuro‐SM model with respect to mapping parameters and coarse‐model parameters are also derived. The sensitivity analysis can be used with a gradient‐based training technique to improve the model training efficiency. The validity and efficiency of the proposed approach are verified through 2 transistor modeling examples and use of the proposed neuro‐SM models in a large‐signal behavior analysis of an amplifier.

Microstructural analysis of an epitaxial AlN thick film/trench-patterned template by three-dimensional reciprocal lattice space mapping technique

Three-dimensional (3D) lattice plane microstructures were investigated at local regions in an epitaxial AlN thick film grown on a trench-patterned AlN/sapphire template. A 3D reciprocal lattice space mapping technique combined with cross-sectional X-ray microdiffraction using an appropriate Bragg reflection quantitatively revealed the inhomogeneity of the lattice structures in the AlN film without loss of spatial resolution. The results showed a strong correlation of the lattice plane tilt/twist and variations with respect to the void configuration, the patterning structure of the template, and the dislocation morphologies confirmed by transmission electron microscopy.

Comprehensive studies of interfacial strain and oxygen vacancy on metal–insulator transition of VO2 film

As a typical strong correlation material, vanadium dioxide (VO2) has attracted wide interest due to its particular metal–insulator transition (MIT) property. However, the relatively high critical temperature (Tc) of ~68 °C seriously hinders its practical applications. Thus modulating the phase transition process and decreasing the Tc close to room temperature have been hot topics for VO2 study. In the current work, we conducted a multi-approach strategy to control the phase transition of VO2 films, including the interfacial tensile/compressive strain and oxygen vacancies. A synchrotron radiation reciprocal space mapping technique was used to directly record the interfacial strain evolution and variations of lattice parameters. The effects of interfacial strain and oxygen vacancies in the MIT process were systematically investigated based on band structure and d-orbital electron occupation. It was suggested that the MIT behavior can be modulated through the combined effects of the interfacial strain and oxygen vacancies, achieving the distinct phase transition close to room temperature. The current findings not only provide better understanding for strain engineering and oxygen vacancies controlling phase transition behavior, but also supply a combined way to control the phase transition of VO2 film, which is essential for VO2 film based device applications in the future.

The mathematics of spatial transparency and mystery: using syntactical data to visualise and analyse the properties of the Yuyuan Garden

Abstract Background One school of thought argues that the Traditional Chinese Private Garden's (TCPG) primary spatial property is that it features both freestanding buildings in space, and spaces freely positions in the landscape, creating a great sense of phenomenal transparency. In contrast, a more traditional interpretation of the TCPG stresses that its primary purpose is to evoke mystery, or provide places of isolation or for retreat. Method This paper examines these two complex, multi-variable propositions using Space Syntax theory, a method which enables a mathematical analysis of the structural and visual configuration of the spaces in a plan to be undertaken. The methods used for the analysis are variations of the convex space and isovist mapping techniques, and the data is analysed mathematically and then visually using heat-maps. The sixteenth century Yuyuan Garden, one of the most famous TCPGs, is used as a test case for the research. Results The results of this study suggest that those features of the TCPG which are associated with mystery are more correlated with its trafficable structure than its visual accessibility. Conversely, the transparency of the TCPG is potentially more related to the directional features of the space than to transparency in isolation. Conclusion This paper presents a computational visualisation and analysis method based on the use of Space Syntax techniques for examining vision and movement potential in a complex garden environment. As demonstrated in the example of the Yuyuan garden, the method is effective for analysing and visualising spatial properties beyond the surface level of forms and shapes. Through the application of this method we have been able to provide a new insight into two of the most famous, but poorly understood perceptual properties of TCPGs: transparency and mystery.