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Quantum dots (QDs) have attracted wide attention from academia and industry because of their advantages such as high emitting efficiency, narrow half-peak width, and continuously adjustable emitting wavelength. QDs light emitting diodes (QLEDs) are expected to become the next generation commercial display technology. This paper reviews the progress of QLED from physical mechanism, materials, to device engineering. The strategies to improve QLED performance from the perspectives of quantum dot materials and device structures are summarized. [ABSTRACT FROM AUTHOR]

Antennas with broadband radiation and small-size are highly required in wireless communication system. The trade-off relation between bandwidth and size became a difficulty when it comes to miniaturized antenna design. A method of realizing antenna miniaturization and bandwidth enhancement at the same time is needed. Monopole antennas are the most common used one in the devices of Internet of Things, Internet of Vehicles, and wireless access points et al. In this paper, a wideband low-profile top-loaded patch monopole antenna based on surface current engineering is proposed. The topology combines a center-fed circular patch with inductive vias. The patch is designed with patterns, which consists of four concentric annular rings and some strips in radial direction. In this way, three resonances are generated, and the pattern is optimized to bring three resonances close to each other. The number of the strips is specially designed to bring three resonances close to each other. By loading the inductive vias on the outermost rings, connecting to the ground, the resonance at low frequencies can be enhanced, as a consequence of the optimized impedance matching. The field distribution is analyzed to verify the operation principle. A prototype is fabricated, and the measured results agree well with the simulated ones. The relative −10 dB bandwidth is 69% and the omnidirectional radiation pattern is stable in the operating band. The antenna achieves a rather wideband radiation while maintaining a low profile. The method of antenna miniaturization and bandwidth enhancement based on surface current engineering paves the way for antenna design in low-profile ultra-wideband applications. [ABSTRACT FROM AUTHOR]

We investigated bandgap engineering of spinel-structured Mg B 2O4 (B = Al, Ga, In) alloys. The trend of bandgap change was tunable from approximated 7.8–3.6 eV by substituting group III cation atoms in Mg B 2O4. To evaluate the doping possibility, we have calculated the natural band alignment and doping pinning energy of the normal and inverse spinel structures of Mg B 2O4 alloys. The calculated doping pinning energies show that spinel-structured Mg B 2O4 alloys can potentially control the electron concentration, but hole doping is difficult. Our computational results are expected to provide new insights into the doping control of ultra-wide bandgap semiconductors. [ABSTRACT FROM AUTHOR]

In this paper, based on first given Lewis–Riesenfeld invariant depicted by a unit vector in parameter space, we inverse engineering the time-dependent Hamiltonian of a system with su(2) Lie algebraic structure. The introduced method is then applied to investigate nonadiabatic Abelian geometric quantum computation. We demonstrate that, by employing the nonadiabatic Berry phase generated through nonadiabatic periodic evolution, a driven two-level system which undergoes a single cyclic evolution along a loop path in Bloch space can realize a universal set of one-qubit gates. Subsequently, under consideration of the influence of the systematic error and dissipation on nonadiabatic process, the result reveals arbitrary one-qubit gate can be implemented with a high fidelity. Moreover, to complete the universal set, arbitrary controlled-U gate is designed by utilizing a driven system consisted of a pair of coupled spin subsystems. [ABSTRACT FROM AUTHOR]

Acquisition of differential signals from low voltage and high impedance sources is difficult when using commonly available laboratory test equipment such as a standard oscilloscope or single ended acquisition system. This paper presents a versatile differential preamplifier for universal signal conditioning. The probe offers a wide input voltage range and can measure signals ranging from a few hundred micro-volts up to 100 V with 1 MHz bandwidth. It also contains a programmable output filter for bandwidth limitation and noise reduction, user-accessible controls for offset adjustment and input coupling mode selection. The probe can be powered through an USB port or by using an internal battery. Input impedance can be made virtually infinite by the JFET input stage, which makes this differential preamplifier usable with a variety of high-impedance sources commonly encountered in the sensors research field and in electronic engineering. Experimental validation shows that the proposed device has better performance levels and interoperability than commercially available instrumentation at a reduced cost, even while using off-the-shelf components. [ABSTRACT FROM AUTHOR]

Understanding defect-phonon interactions in solid-state devices is crucial for improving our current knowledge of quantum platforms. In this work, we develop first-principles calculations for a defect composed of two spin- 1 / 2 particles that interact with phonon modes in a one-dimensional lattice. We follow a bottom-up approach that begins with a dipolar magnetic interaction to ultimately derive the spectral density function and time-local master equation that describes the open dynamics of the defect. We provide theoretical and numerical analysis for the non-Markovian (NM) features of the defect-phonon dynamics induced by a pure dephasing channel acting on the Bell basis. Finally, we analyze two measures of NM based on the canonical rates and Coherence, shedding more light on the role of the spectral density function and temperature; and envisioning experimental realizations. [ABSTRACT FROM AUTHOR]

In this paper, we apply the deep learning network to the inverse engineering of electromagnetically induced transparency (EIT) in terahertz metamaterial. We take three specific points of the EIT spectrum with six inputs (each specific point has two physical values with frequency and amplitude) into the deep learning model to predict and inversely design the geometrical parameters of EIT metamaterials. We propose this algorithm for the general inverse design of EIT metamaterials, and we demonstrate that our method is functional by taking one example structure. Our deep learning model exhibits a mean square error of 0.0085 in the training set and 0.014 in the test set. We believe that this finding will open a new approach for designing geometrical parameters of EIT metamaterials, and it has great potential to enlarge the applications of the THz EIT metamaterial. [ABSTRACT FROM AUTHOR]

Symmetric droplet-etched quantum dots (QDs) are the leading candidate for generating high-performance polarization-entangled photon pairs. One of the challenges is how to precisely engineer the properties of QDs by controlling the morphology of etched nanoholes. In this paper, we systematically investigate the influence of the underlying material, showing the morphological evolution of the nanohole structure as well as symmetric GaAs QDs with an average fine-structure splitting (FSS) of (5.9 ± 1.2) μeV. Moreover, we develop a theoretical model that quantitatively reproduces the experimental data and provides insights into the mechanisms governing the relationship between the anisotropy of nanoholes in the crystallographic direction and the growth parameters. Our theoretical analysis also indicates how to improve the symmetry of nanoholes to meet the requirements for implementing QDs in entangled photon sources. [ABSTRACT FROM AUTHOR]

Since the emergence of one-dimensional nanostructures, in particular the bandgap-graded semiconductor nanowires/ribbons or heterostructures, lots of attentions have been devoted to unraveling their intriguing properties and finding applications for future developments in optical communications and integrated optoelectronic devices. In particular, the ability to modulate the bandgap along a single nanostructure greatly enhances their functionalities in optoelectronics, and hence these studies are essential to pave the way for future high-integrated devices and circuits. Herein, we focus on a brief review on recent advances about the synthesis through a magnetic-pulled chemical vapor deposition approach, crystal structure and the unique optical and electronic properties of on-nanostructures semiconductors, including axial nanowire heterostructures, asymmetrical/symmetric bandgap gradient nanowires, lateral heterostructure nanoribbons, lateral bandgap graded ribbons. Moreover, recent developments in applications using low-dimensional bandgap modulated structures, especially in bandgap-graded nanowires and heterostructures, are summarized, including multicolor lasers, waveguides, white-light sources, photodetectors, and spectrometers, where the main strategies and unique features are addressed. Finally, future outlook and perspectives for the current challenges and the future opportunities of one-dimensional nanostructures with bandgap engineering are discussed to provide a roadmap future development in the field. [ABSTRACT FROM AUTHOR]

In this paper, we present a new Z-shaped line tunnel field effect transistor (TFET) employing drain doping engineering with a split drain structure (SD-ZHP-TFET). The split drain (SD) approach in the proposed ZHP-TFET helps increasing tunneling width at the channel-drain interface, reducing ambipolarity. Moreover, a horizontal pocket (HP) is implanted in the source region to boost the ON-current of the proposed SD-ZHP-TFET structure. The effect of both these approaches in the line-TFET provides higher ON-current and reduces ambipolarity significantly. Split drain structure in the ZHP-TFET exhibits a three-decade improvement in the ambipolar current without affecting the subthreshold (SS) and leakage current significantly. A calibrated simulation study of split drain thickness (tu) and drain region doping variation on the analog performance are investigated using the technology computer-aided design device simulator. Moreover, the high-frequency figure of merit regarding total gate capacitance (Cgg), unit-gain cut-off frequency (fT) is analysed. It is found that the drain doping improves the cut-off frequency from 1.8 GHz in ZHP-TFET to 2.2 GHz in the proposed SD-ZHP-TFET structure. Thus the proposed device is capable of providing higher ION/IOFF (≈1013) and ION/IAMB (≈1013) ratio with an average SS of 44 mV/decade. [ABSTRACT FROM AUTHOR]

In this paper, trench superjunction MOS (SJ UMOS) utilizing workfunction engineered stepped gate for performance enhancement is proposed. N+ polysilicon (Φm = 4.17 eV) layer in between two P+ polysilicon (Φm = 5.25 eV) layer connected by a metal gate is incorporated in the proposed device. Additionally, gate oxide thickness is increased in steps from source to drain resulting in enhanced gate-source capacitance and reduced gate-drain capacitance. The electrical behavior of conventional and proposed device is investigated using 2D numerical simulations. The results indicate 19.5% reduction in specific resistance without degrading the breakdown voltage. Further, the proposed structure also exhibits 28.9% reduction in specific gate to drain charge, 30.5% increment in gate to source charge and 54% reduction in switching delay. In addition to this, Baliga's figure of merit (BFOM) along with other technology figure of merit (FOM) has also been evaluated, demonstrating a 26% increment in BFOM. The significant improvement in FOM is attributed to reduced specific resistance and gate to drain charge of the proposed structure. Additionally, the impact of temperature on device performance is also evaluated and no degradation in the device parameters is observed. [ABSTRACT FROM AUTHOR]

We propose a scheme to inverse engineer the Hamiltonian of any general driven three-level system by employing a SU(3) transformation. For special cases, the scheme is then introduced to explore nonadiabatic dynamic evolution of systems with two-photon resonance. We demonstrate that, by selecting the control parameters with explicit function forms, both the ideal process and the practical evolution driving with the truncation of pulses, systematic error and decaying can implement fast population transfer with high fidelity. Moreover, the nonadiabatic passages are not reconstructed by the superadiabatic approach. [ABSTRACT FROM AUTHOR]

In recent years many efforts have been undertaken to simplify coil designs for stellarators due to the difficulties in fabricating non-planar coils. The FOCUS code removes the need for a winding surface and represents the coils as arbitrary curves in 3D. In the following work, the implementation of a spline representation for the coils in FOCUS is described, along with the implementation of a new engineering constraint to design coils with a straighter outer section. The new capabilities of the code are shown as an example on HSX, NCSX, and a prototype quasi-axisymmetric reactor-sized stellarator. The flexibility granted by splines along with the new constraint will allow for stellarator coil designs with improved accessibility and simplified maintenance. [ABSTRACT FROM AUTHOR]

A look at the history of this journal reveals some significant trends in the evolution of measurement science and shows how key papers published in the journal have influenced these developments. [ABSTRACT FROM AUTHOR]

After γ-ray irradiation treatment, a monolayer tungsten diselenide could be transitioned into an n-doped semiconductor due to the anion vacancies created by the radiation. Transmission electron microscope studies showed clear chemical modulation with atomically sharp interface. Change in the lattice vibrational modes induced by passivation of oxygen is captured by Raman spectroscopy. The frequency shifts in both in-plane and out-of-plane modes are dependent linearly on the oxidation content. We observe a negative trion, which is a neutral exciton bound with an electron, in the photoluminescence spectra. The binding energy of this trion is estimated to be ∼90 meV, making it a tightly bound exciton. The first-principles calculation suggests that an increase in the anion vacancy population is generally accompanied by a transition from a direct gap material to an indirect one. This opens up a new venue to engineer the electronic properties of transition metal dichalcogenides by using irradiation. [ABSTRACT FROM AUTHOR]

We propose a universal strategy to realize a broadband control on arbitrary scatterers, through multiple coherent beams. By engineering the phases and amplitudes of incident beams, one can suppress the dominant scattering partial waves, making the obstacle lose its intrinsic responses in a broadband spectrum. The associated coherent beams generate a finite and static region, inside which the corresponding electric field intensity and Poynting vector vanish. As a solution to go beyond the sum-rule limit, our methodology is also irrespective of inherent system properties, as well as extrinsic operating wavelength, providing a non-invasive control on the wave-obstacles interaction for any kinds of shape. [ABSTRACT FROM AUTHOR]

Exploring emergent phenomena in complex oxide heterostructures by interfacial engineering is the frontier of the oxide electronics. The heterointerface formed by oxides with different structures is particularly interesting since symmetry mismatch may produce considerable interface reconstruction and unexpected emergent phenomena. Here, we demonstrate the abnormal magnetic anisotropy in SrFeO2.5/La2/3Ba1/3MnO3/SrFeO2.5 trilayers that are consisted of the perovskite/brownmillerite heterostructures. The compressively strained La2/3Ba1/3MnO3 layer sandwiched between the two SrFeO2.5 layers exhibits in-plane magnetic anisotropy, while the La2/3Ba1/3MnO3 bare film with the same strain state shows perpendicular magnetic anisotropy at low temperature. The high-resolution scanning transmission electron microscope and x-ray absorption spectroscopy analysis reveal the off-center displacement of the Mn ions at interfaces. This would cause a strong orbital reconstruction of Mn ions at the interface and thus the in-plane magnetic anisotropy. This work shows the great potential to explore novel phenomena in artificially designed multilayers by interfacial engineering. [ABSTRACT FROM AUTHOR]

In this work, a new two-dimensional material with excellent stability and an indirect band gap of 3.304 eV (HSE06), called SiPS, is predicted by using first-principles calculations. The electron calculations demonstrate that SiPS exhibits strong anisotropies in electron effective mass and transport ability. At room temperature (300 K), the calculated electron mobility along y direction is 172.6 cm2 V−1 s−1, which is about 108 times larger than that along x direction (1.6 cm2 V−1 s−1). Under the biaxial strain, the band gap can be tuned (2.265–3.585 eV) as well as the electron effective mass and transport ability, especially the remarkable reduction of electron effective mass and the improvement of electron mobility along x direction. In addition, in the exploration of bilayer SiPS with four stacking patterns, it can be observed that pattern III triggers the transformation of bilayer SiPS from indirect to direct band gap. The electron mobility of bilayer SiPS can be tuned by the different stacking patterns, and the results show that the electron mobility of patterns I and II are 3.3–6.2 and 375.2–440.3 cm2 V−1 s−1 along x and y direction, respectively, which are over two times higher than those of monolayer SiPS. For patterns III and IV, the electron mobility along x and y directions exhibit a small difference, with the values of 74.5–65.3 and 64.1–34.4 cm2 V−1 s−1, respectively. These advantaged results shed light on two-dimensional SiPS for promising applications in developing unidirectional or bidirectional conductive electronic devices. [ABSTRACT FROM AUTHOR]

White light-emitting diodes (WLEDs) based on all-inorganic perovskite CsPbX3 (X = Cl, Br, I) quantum dots (QDs) have attracted much attention and rely on mixing several colors of perovskites. However, this inevitably leads to a non-uniform light distribution and serious light loss. Here, a novel strategy was demonstrated to obtain white emission by combining the orange and blue emission from CsPb/Mn(Cl/Br)3 QDs. Notably, highly efficient white emission with a photoluminescence quantum yield of 94% was achieved by an anion exchange surface engineering (AESE) strategy. After AESE treatment the surface traps can be eliminated, resulting in improved exciton and Mn2+ emission. A prototype WLED device was fabricated and exhibited excellent optical stability, demonstrating great potential for perovskite QDs in the field of optoelectronics. [ABSTRACT FROM AUTHOR]

Floquet engineering or coherent time-periodic driving of quantum systems has been successfully used to synthesize Hamiltonians with novel properties. In ultracold atomic systems, this has led to experimental realizations of artificial gauge fields, topological bandstructures, and observation of dynamical localization, to name a few. Here we present a Floquet-based framework to stroboscopically engineer Hamiltonians with spatial features and periodicity below the diffraction limit of light used to create them by time-averaging over various configurations of a 1D optical Kronig–Penney (KP) lattice. The KP potential is a lattice of narrow subwavelength barriers spaced by half the optical wavelength (λ/2) and arises from the nonlinear optical response of the atomic dark state. Stroboscopic control over the strength and position of this lattice requires time-dependent adiabatic manipulation of the dark-state spin composition. We investigate adiabaticity requirements and shape our time-dependent light fields to respect the requirements. We apply this framework to show that a λ/4-spaced lattice can be synthesized using realistic experimental parameters as an example, discuss mechanisms that limit lifetimes in these lattices, explore candidate systems and their limitations, and treat adiabatic loading into the ground band of these lattices. [ABSTRACT FROM AUTHOR]

In this paper we present activities that can help students deepen their understanding of DC circuits and develop practical competences. The students investigate electric properties of commercially available conductive thread and solve a practical design task using the thread. The activities follow the framework of investigative science learning environment (ISLE)—an approach to learning and teaching that helps students learn fundamental physics concepts by engaging them in processes that mirror those used by physicists when they develop new knowledge and use it for practical applications. In this paper this framework is extended to engineering. [ABSTRACT FROM AUTHOR]

The stability of flow focusing taking place in a converging-diverging nozzle, as well as the size of the resulting microjets, is examined experimentally in this paper. The results obtained in most aspects of the problem are similar to those of the classical plate-orifice configuration. There is, however, a notable difference between flow focusing in nozzles and in the plate-orifice configuration. In the former case, the liquid meniscus oscillates laterally (global whipping) for a significant area of the control parameter plane, a phenomenon never observed when focusing with the plate-orifice configuration. Global whipping may constitute an important drawback of flow focusing with nozzles because it reduces the robustness of the technique. [ABSTRACT FROM AUTHOR]

The present paper gives an overview of the different routes to grow SiC single crystals. The focus is put on the new emerging processes compared with the well established ones. A review of the process engineering modelling is given. Finally, some selected results are pointed out as they should be considered for the future development of SiC material. [ABSTRACT FROM AUTHOR]

While quantum devices rely on interactions between constituent subsystems and with their environment to operate, native interactions alone often fail to deliver targeted performance. Coherent pulsed control provides the ability to tailor effective interactions, known as Hamiltonian engineering. We propose a Hamiltonian engineering method that maximizes desired interactions while mitigating deleterious ones by conducting a pulse sequence search using constrained optimization. The optimization formulation incorporates pulse sequence length and cardinality penalties consistent with linear or integer programming. We apply the general technique to magnetometry with solid state spin ensembles in which inhomogeneous interactions between sensing spins limit coherence. Defining figures of merit for broadband Ramsey magnetometry, we present novel pulse sequences which outperform known techniques for homonuclear spin decoupling in both spin-1/2 and spin-1 systems. When applied to nitrogen vacancy (NV) centers in diamond, this scheme partially preserves the Zeeman interaction while zeroing dipolar coupling between negatively charged NV− centers. Such a scheme is of interest for NV− magnetometers which have reached the NV−–NV− coupling limit. We discuss experimental implementation in NV ensembles, as well as applicability of the current approach to more general spin bath decoupling and superconducting qubit control. [ABSTRACT FROM AUTHOR]

Springs are used for a wide range of applications in physics and engineering. Possibly, one of their most common uses is to study the nature of restoring forces in oscillatory systems. While experiments that verify Hooke's law using springs are abundant in the physics literature, those that explore the combination of several springs together are very rare. In this paper, an experiment designed to study the static properties of a combination of springs in series using only one single spring is presented. Paint marks placed on the coils of the spring allowed us to divide it into segments, and consider it as a collection of springs connected in series. The validity of Hooke's law for the system and the relationship between the spring constants of the segments and the spring constant of the entire spring are verified experimentally. The easy setup, accurate results, and educational benefits make this experiment attractive and useful for high school and first-year college students. [ABSTRACT FROM AUTHOR]

This paper studies the Josephson-like tunnelling in two-component Bose-Einstein condensates coupled with microwave field, which is in respond to various attractive and repulsive atomic interaction under the various aspect ratio of trapping potential. It is very interesting to find that the dynamic of Josephson-like tunnelling can be controlled from fast damped oscillations to nondamped oscillation, and relative number of atoms changes from asymmetric occupation to symmetric occupation correspondingly. [ABSTRACT FROM AUTHOR]

In this paper, a hybrid optical method combining coherent gradient sensing (CGS) with caustics is introduced. The application of hybrid technology to the fracture investigation of three-point bending specimens with the initial inclined edge-crack is performed. Both the shadow patterns of caustics and CGS fringe patterns are simultaneously recorded from the same specimen by different photographic frames. Based on the K-dominance condition, the stress intensity factors at the crack tip are extracted by means of the characteristic size of caustic spot and the fringe order of CGS, respectively. The influences of different crack combinations on fracture characterizations are analysed. These results will be useful in the reliable design and strength evaluation of engineering structures. [ABSTRACT FROM AUTHOR]

The nonlinear material metallic rubber is used widely in engineering, especially in isolation systems. This paper describes the effects of loading processes on dry friction damping performance, which is based on the Masing model and its derivations. First, the primary loading lines of the full hysteresis loop are obtained from single axial experiments. The lines are used to describe the full loop in the process of coordinate transform. Then, two-dimensional perpendicular loading experiments are conducted to investigate the relationship between axial loading and tangential loading. In the experiments, different loading amplitudes in axial and tangential directions are adopted to study their effects on the damping performance. Particular attention is paid to the description of the relationship between relative frictional force and the displacement in its perpendicular direction. In addition, a test rig is designed for the study. [ABSTRACT FROM AUTHOR]

We present a 3D vision system based on the projection of a single fringe pattern of incoherent light and on robust phase coding. A novel projection scheme is exploited: two sinusoidal gratings at different frequencies are combined into a single pattern, and phase demodulated in the natural domain of the signal. The method yields the determination of two phase maps, whose sensitivity to height variations is proportional to the frequencies of the two grating components. Robust phase unwrapping is implemented, where the phase ambiguity of the fine grating component is naturally compensated for by the phase values evaluated by using the coarse one. As a result, both a high measurement resolution and an extended height range are obtained. The method requires the projection of a static pattern. Hence, even a low-cost slide projector can be used as the projection device. Moreover, the system turns out to be suitable for dynamic and real-time measurement applications. In addition, it may be fruitfully used as the acquisition sensor in full-optical reverse engineering applications. In this paper, the measurement principle and the design issues of the instrument are presented. The measurement performances are discussed, in relation to both the input–output characteristic of the instrument and the acquisition of free-form shapes. [ABSTRACT FROM AUTHOR]

This paper describes the application of the adjoint method to the history matching problem in reservoir engineering. The history matching problem consists in adjusting a set of parameters, in this case the permeability distribution, in order to match the data obtained with the simulator to the actual production data in the reservoir. Several numerical experiments are presented which show that our method is able to reconstruct the unknown permeability distribution in a reliable and efficient way from synthetic data provided by an independent numerical forward modelling code. An efficient and flexible regularization scheme is introduced as well, which stabilizes the inversion and enables the reservoir engineer to incorporate certain types of prior information into the final result. [ABSTRACT FROM AUTHOR]

The electronic and magnetic properties of boron nitride nanoribbons (BNNRs) with square–octagon (4 | 8) line defects (LD-(4 | 8)), parallel to their edges, have been investigated by first-principles calculations. It is found that the zigzag type LD-(4 | 8) BNNR with boron terminated edges is an antiferromagnetic (AFM‘ + − + −’) insulator with an indirect bandgap, but that with nitrogen terminated edges has two degenerate ground states with the same energy, among which one is ferromagnetic (FM ‘ + + + +’) half-metallic and the other is AFM ‘ + + − −’ metallic. In contrast, it is more interesting to find that the bare and fully-hydrogen terminated armchair edge BNNRs with unsymmetric (4 | 8) line defects have an indirect and direct gap, respectively, both of which show a characteristic three family oscillation behavior, depending only on the ribbon width in its narrower part, but not the whole BNNR’s width. Finally, the stabilities of a two-dimensional h-BN sheet with a zigzag or armchair type LD-(4 | 8) in it are further confirmed, among which the one with the armchair type LD-(4 | 8) is much more stable than that with the zigzag type counterpart. [ABSTRACT FROM AUTHOR]

An enhanced octree data representation is developed for use in atomistic simulations of the evolution of complex multivalued surfaces appearing during anisotropic etching of crystalline silicon in micro electro mechanical systems (MEMS) applications. The octree provides a good balance between accuracy, memory efficiency and calculation speed. In combination with the octree, a step flow-based cellular automaton (CA) model is considered, which can be used to convert the experimental macroscopic etch rates into atomistic removal rates for direct use in the simulations. This involves minimizing the global error between the experimental values and the non-linear analytical expressions of the etch rates for a small set of chosen orientations. The orientations where the etch rate suffers a sudden change against the cutting angle play a crucial role to generate an optimal solution. The simulated etch rates for KOH and KOH/IPA systems in different concentrations show good agreement with the experiments. Due to the improved description of the anisotropy, the propagation of the etch front in realistic engineering applications can be simulated accurately. [ABSTRACT FROM AUTHOR]

The dc Josephson effect in superconductor / insulator / normal metal / insulator /ferromagnetic superconductor junctions has been studied. We calculate the dc Josephson current based on the Bogoliubov de Gennes equation. The Josephson current is derived as a function of exchange field in ferromagnetic superconductor, normal metal thickness and insulating barrier strength. It is found that there exists an oscillation relation between the critical Josephson current and the normal metal thickness. The oscillation amplitude decreases as the thickness of the normal metal increases or the exchange field augments. [ABSTRACT FROM AUTHOR]

The considerable need to enhance data and hardware security suggest one possible future for electronics where it is possible to destroy them and even make them disappear physically. This paper reports a type of destructive electronics which features fast transience from chemical dissolution on-demand triggered in an electrochemical-mechanical manner. The detailed materials, mechanics, and device construction of the destructive electronics are presented. Experiment and analysis of the triggered releasing and transience study of electronic materials, resistors and metal-oxide-semiconductor field effect transistors illustrate the key aspects of the destructive electronics. The reported destructive electronics is useful in a wide range of areas from security and defense, to medical applications [ABSTRACT FROM AUTHOR]

This paper discusses a statistical second-order two-scale (SSOTS) analysis and computation for a heat conduction problem with a radiation boundary condition in random porous materials. Firstly, the microscopic configuration for the structure with random distribution is briefly characterized. Secondly, the SSOTS formulae for computing the heat transfer problem are derived successively by means of the construction way for each cell. Then, the statistical prediction algorithm based on the proposed two-scale model is described in detail. Finally, some numerical experiments are proposed, which show that the SSOTS method developed in this paper is effective for predicting the heat transfer performance of porous materials and demonstrating its significant applications in actual engineering computation. [ABSTRACT FROM AUTHOR]

It is very difficult to detect weak fault signatures due to the large amount of noise in a wind turbine system. Multiscale noise tuning stochastic resonance (MSTSR) has proved to be an effective way to extract weak signals buried in strong noise. However, the MSTSR method originally based on discrete wavelet transform (DWT) has disadvantages such as shift variance and the aliasing effects in engineering application. In this paper, the dual-tree complex wavelet transform (DTCWT) is introduced into the MSTSR method, which makes it possible to further improve the system output signal-to-noise ratio and the accuracy of fault diagnosis by the merits of DTCWT (nearly shift invariant and reduced aliasing effects). Moreover, this method utilizes the relationship between the two dual-tree wavelet basis functions, instead of matching the single wavelet basis function to the signal being analyzed, which may speed up the signal processing and be employed in on-line engineering monitoring. The proposed method is applied to the analysis of bearing outer ring and shaft coupling vibration signals carrying fault information. The results confirm that the method performs better in extracting the fault features than the original DWT-based MSTSR, the wavelet transform with post spectral analysis, and EMD-based spectral analysis methods. [ABSTRACT FROM AUTHOR]

The Guide to the Expression of Uncertainty in Measurement (GUM) is the master document for measurement uncertainty evaluation. However, the GUM may encounter problems and does not work well when the measurement data have poor information. In most cases, poor information means a small data sample and an unknown probability distribution. In these cases, the evaluation of measurement uncertainty has become a bottleneck in practical measurement. To solve this problem, a novel method called the grey relational approach (GRA), different from the statistical theory, is proposed in this paper. The GRA does not require a large sample size or probability distribution information of the measurement data. Mathematically, the GRA can be divided into three parts. Firstly, according to grey relational analysis, the grey relational coefficients between the ideal and the practical measurement output series are obtained. Secondly, the weighted coefficients and the measurement expectation function will be acquired based on the grey relational coefficients. Finally, the measurement uncertainty is evaluated based on grey modeling. In order to validate the performance of this method, simulation experiments were performed and the evaluation results show that the GRA can keep the average error around 5%. Besides, the GRA was also compared with the grey method, the Bessel method, and the Monte Carlo method by a real stress measurement. Both the simulation experiments and real measurement show that the GRA is appropriate and effective to evaluate the measurement uncertainty with poor information. [ABSTRACT FROM AUTHOR]

The reliable measurement of state tendency for a hydro-turbine generating unit (HGU) is significant in guaranteeing the security of the unit and promoting stability of the power system. For this purpose, an aggregated ensemble empirical mode decomposition (AEEMD) and optimized support vector regression (SVR)-based hybrid model is developed in this paper in order to enhance the measuring accuracy of state tendency for a HGU. First of all, the non-stationary time series of the state signal are decomposed into a collection of intrinsic mode functions (IMFs) by EEMD. Subsequently, to obtain the refactored intrinsic mode functions (RIMFs), the IMFs with different scales are aggregated with the proposed reconstruction strategy in consideration of the frequency and energy conditions. Later, the phase–space matrix in accordance with each RIMF is deduced by phase–space reconstruction and all the RIMFs are predicted through establishing homologous optimal SVR forecasting models with a grid search. Finally, the ultimate measuring values of state tendency can be determined through the accumulation of all the RIMF forecasting values. Furthermore, the effectiveness of the proposed method is validated in engineering experiments and comparative analyses. [ABSTRACT FROM AUTHOR]

Why is the development of a deep trench superjunction (SJ) MOSFET above 600 V and under 8.0 mohm · cm2 difficult? A deep trench SJ MOSFET is expected to have a low turn-on resistance because the post thermal process after the epitaxial process, which is normally used in a multi-step epitaxy structure, is unnecessary. When designing a deep trench SJ MOSFET, the trench angle is the most important factor because this determines the breakdown voltage (BV) and BV variations. In this paper, we investigated how the trench angle affects the BV and BV window as a condition of the possible thermal process. By employing a physical concept, ΔCharge, we explained why the maximum BV is decreased and the BV window is increased as the trench angle decreases. Also, we systematically scrutinized the transition of the vertical electric field by varying the trench angle. Furthermore, in a real case, the principle of the trench angle which contributes to the deviation of the charge imbalance and specific resistance of SJ is described. Finally, we discuss the challenge of SJ MOSFET development in the industry. [ABSTRACT FROM AUTHOR]

A necessity to address a wide spectrum of engineering problems in ITER determined the need for efficient tools for modeling of the magnetic environment and force interactions between the main components of the magnet system. The assessment of the operating window for the machine, determined by the electro-magnetic (EM) forces, and the check of feasibility of particular scenarios play an important role for ensuring the safety of exploitation. Such analysis-powered prevention of damages forms an element of the Machine Operations and Investment Protection strategy. The corresponding analysis is a necessary step in preparation of the commissioning, which finalizes the construction phase. It shall be supported by the development of the efficient and robust simulators and multi-physics/multi-system integration of models. The developed numerical model of interactions in the ITER magnetic system, based on the use of pre-computed influence matrices, facilitated immediate and complete assessment and systematic specification of EM loads on magnets in all foreseen operating regimes, their maximum values, envelopes and the most critical scenarios. The common principles of interaction in typical bilateral configurations have been generalized for asymmetry conditions, inspired by the plasma and by the hardware, including asymmetric plasma event and magnetic system fault cases. The specification of loads is supported by the technology of functional approximation of nodal and distributed data by continuous patterns/analytical interpolants. The global model of interactions together with the mesh-independent analytical format of output provides the source of self-consistent and transferable data on the spatial distribution of the system of forces for assessments of structural performance of the components, assemblies and supporting structures. The numerical model used is fully parametrized, which makes it very suitable for multi-variant and sensitivity studies (positioning, off-normal events, asymmetry, etc). The obtained results and matrices form a basis for a relatively simple and robust force processor as a specialized module of a global simulator for diagnostic, operational instrumentation, monitoring and control, as well as a scenario assessment tool. This paper gives an overview of the model, applied technique, assessed problems and obtained qualitative and quantitative results. [ABSTRACT FROM AUTHOR]

Optical tire sensors are powerful engineering tools that can reveal the mechanisms behind tire-road interactions. This paper presents a laser-based sensor system to measure tire-tread block deformation. The methodology and corresponding procedure for the system are introduced. Practical issues, such as tire sensor localization, are discussed. Validation experiments were conducted on a chassis dynamometer, and an asymmetric tire tread deformation along the contact patch was observed. It is proposed that asymmetric tread deformation is due to rolling resistance. The measurements under different operational conditions, including the rolling direction, wheel load, rolling velocity, and inflation pressure, were analyzed in the context of rolling resistance. [ABSTRACT FROM AUTHOR]

A call for papers on the celebration of the 20th anniversary of quantum state engineering is presented.

As the possibility to decouple temporal and spatial variations of the electromagnetic field, leading to a wavelength stretching, has been recognized to be of paramount importance for practical applications, we generalize the idea of stretchability from the framework of electromagnetic waves to massive particles. A necessary and sufficient condition which allows one to identify energetically stable configuration of a 1D quantum particle characterized by arbitrary large spatial regions where the associated wave-function exhibit a flat, non-zero profile is presented, together with examples on well-known and widely used potential profiles and an application to 2D models. [ABSTRACT FROM AUTHOR]

It has been proven that portal dosimetry can be derived from a mirror-based fluorescent EPID system by applying multiple kernels that are position dependent. The purpose of this study is to show that patient-specific IMRT/VMAT verification with a single kernel which is acquired from a series of output measurements of a few field sizes is feasible using a commercially available phosphor-screen–based geometric QA system. The optical scatter component in the RavenQA™ (LAP GmbH Laser Applications; Lüneberg, Germany) is corrected by deconvolution with a two-dimensional (2D) spatially invariant single optical scatter kernel (OSK). We assume that the OSK is a 2D isotropic point spread function that decreases as a function of distance from the scatter center. The OSK is determined by comparing output factors of various field sizes. We report on performance testing of the system using 12 intensity-modulated radiation therapy and three volumetric-modulated arc therapy cases. A single spatially invariant OSK can be employed, because the shapes of the OSK across the image plate are almost identical. The average 3%/3 mm gamma passing rate for 15 patients was 97.6%  ±  1.1%. The passing rate was  >95% for all patients. It is feasible to perform the patient-specific IMRT/VMAT verification with a single kernel using a commercially available phosphor-screen-based mechanical QA device in accordance with AAPM TG-142. It is also practical to implement since it only requires to measure the optical intensities of the field centers of several square fields, in order to obtain the OSK. [ABSTRACT FROM AUTHOR]

The influence of the inhomogeneous tissue layer on the generation of acoustic vortices (AV) is studied theoretically and experimentally based on the phase screen model. By considering the time-shift of a random phase screen, the formula of acoustic pressure for the AV beam generated by a circular array of eight planar piston sources is derived. With the actual correlation length of the abdominal wall, numerical simulations before and after the insertion of the inhomogeneous tissue layer are conducted, and also demonstrated by experimental measurements. It is proved that, when the thickness variation of the phase screen is less than one wavelength, no significant influence on the generation of AVs can be produced. The variations of vortex nodes and antinodes in terms of the location, shape, and size of AVs are not obvious. Although the circular pressure distribution might be deformed by the phase interference with a larger thickness variation, AVs can still be generated around the center axis with perfect phase spirals in a reduced effective radius. The favorable results provide the feasibility of AV generation inside the human body and suggest the application potential of AVs in object manipulation for biomedical engineering. [ABSTRACT FROM AUTHOR]

In this paper, we outline the basics of the dislocation-engineered method for the production of silicon LEDs. We describe the manufacture processes and the device structures and their method of operation. The microstructure of the dislocation loops and the critical array parameters are discussed, emphasizing the importance of correctly engineering the array so as to optimize the performance of such devices. We show how the basic 1.2 um emitter technology can be extended to give other wavelengths such as 1.3, 1.5 and 1.6 um of interest for an operation in the extended optical communications band. [ABSTRACT FROM AUTHOR]

Gauge-invariant twistor variables are found for the massive spinning particle with -extended local worldline supersymmetry, in spacetime dimensions The twistor action is manifestly Lorentz invariant but the anticommuting spin variables appear exactly as in the non-relativistic limit. This allows a simple confirmation that the quantum spinning particle has either spin one or spin zero, and that is quantum inconsistent for [ABSTRACT FROM AUTHOR]

We propose a new laser reflection confocal large-radius measurement (RCLRM) method. By utilizing the precise correspondence relationship between the peak point of the confocal curve and the convergence point of the multi-reflected measuring beam, we identify the position of the test lens. With a distance interferometer, we obtain the position variation of the test lens with different reflection times. Therefore, a fast and precise large-radius measurement is achieved with a shorter measuring system. Additionally, the RCLRM significantly enhances the measurement accuracy by using conic fitting. The theoretical analyses and experiments indicate that the relative expanded uncertainty is better than 0.008% (k  =  2). [ABSTRACT FROM AUTHOR]

In navigation applications, the presence of an unknown bias in the measurement of rate gyros is a key performance-limiting factor. In order to estimate the gyro bias and improve the accuracy of attitude measurement, we proposed a new method which uses the rotation of an inertial measurement unit, which is independent from rigid body motion. By actively changing the orientation of the inertial measurement unit (IMU), the proposed method generates sufficient relations between the gyro bias and tilt angle (roll and pitch) error via ridge body dynamics, and the gyro bias, including the bias that causes the heading error, can be estimated and compensated. The rotation inertial measurement unit method makes the gravity vector measured from the IMU continuously change in a body-fixed frame. By theoretically analyzing the mathematic model, the convergence of the attitude and gyro bias to the true values is proven. The proposed method provides a good attitude estimation using only measurements from an IMU, when other sensors such as magnetometers and GPS are unreliable. The performance of the proposed method is illustrated under realistic robotic motions and the results demonstrate an improvement in the accuracy of the attitude estimation. [ABSTRACT FROM AUTHOR]

The microwave conductance decay (MCD) technique combining an initially matched transmission line setup and picosecond optical excitation was developed and applied for the monitoring of transmitted and reflected microwave power transients in a 4H-SiC epilayer in a wide excitation range, from 2  ×  1014 to 1018 cm−3. The excitation-dependent decrease in measurement sensitivity in the power-law relations of the transients was observed at excess carrier densities above 1016 cm−3 due to the line mismatches and decrease in the internal microwave field in the illuminated sample. The calibration procedure of MCD data on excess carrier density was applied for the correction of the MCD transients and resulted in nearly identical MCD kinetics in the reflection and transmission. In a 35 μm-thick n-type 4H-SiC epilayer, the tendencies of the gradual decrease of the initial decay time with an excitation increase and the excitation-enhanced carrier recombination rate in MCD tails were analyzed numerically. These tendencies were attributed to the excitation dependent surface recombination rate and the enhanced trap-related bulk recombination, correspondingly. [ABSTRACT FROM AUTHOR]