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Unlike the conventional facial expressions, micro-expressions are involuntary and transient facial expressions capable of revealing the genuine emotions that people attempt to hide. Therefore, they can provide important information in a broad range of applications such as lie detection, criminal detection, etc. Since micro-expressions are transient and of low intensity, however, their detection and recognition is difficult and relies heavily on expert experiences. Due to its intrinsic particularity and complexity, video-based micro-expression analysis is attractive but challenging, and has recently become an active area of research. Although there have been numerous developments in this area, thus far there has been no comprehensive survey that provides researchers with a systematic overview of these developments with a unified evaluation. Accordingly, in this survey paper, we first highlight the key differences between macro- and micro-expressions, then use these differences to guide our research survey of video-based micro-expression analysis in a cascaded structure, encompassing the neuropsychological basis, datasets, features, spotting algorithms, recognition algorithms, applications and evaluation of state-of-the-art approaches. For each aspect, the basic techniques, advanced developments and major challenges are addressed and discussed. Furthermore, after considering the limitations of existing micro-expression datasets, we present and release a new dataset — called micro-and-macro expression warehouse (MMEW) — containing more video samples and more labeled emotion types. We then perform a unified comparison of representative methods on CAS(ME) $^2$ 2 for spotting, and on MMEW and SAMM for recognition, respectively. Finally, some potential future research directions are explored and outlined. [ABSTRACT FROM AUTHOR]

A quasi-mixed-potential layered medium Green’s function (QMP-LMGF) is proposed for non-Galerkin surface integral equation (SIE) formulations in the modeling of homogeneous dielectric objects in layered medium. The formulation is derived based on the pilot vector potential approach. In this method, the field-type LMGF in the $L$ -operator is decomposed into two parts, a “vector potential” term in a dyadic form, and a “scalar potential” term in a vector form, to represent the field components from current and charge sources, respectively. Since the proposed two potential terms (vector potential and scalar potential) do not satisfy the Lorenz gauge, we term them as quasi-mixed-potentials. The property of the two potentials is investigated to reveal that the proposed QMP-LMGF is compatible with the vector and scalar potentials in free space. Moreover, due to the continuity of the integration kernels across the interfaces, undesired line integrals are absent in the proposed QMP-LMGF when the objects are straddling different layers. Three popular non-Galerkin SIEs for dielectric objects in layered medium are studied, and the corresponding numerical results are demonstrated to validate the proposed method. [ABSTRACT FROM AUTHOR]

We propose to suppress high-power microwave pulses (HPMPs) using nonlinear dispersion and filtering natures of spoof surface plasmon polaritons (SSPPs). Frequency components of a short HPMP are distributed in time domain due to different group velocities and partly cutoff on SSPP transmission lines (TLs), leading to peak suppression of HPMP. To illustrate the protection mechanism in real microwave engineering, an SSPP mono-pulse antenna is designed. Sum and difference beam functions of the antenna are demonstrated by both simulations and experiments. For easy comparison, a microstrip mono-pulse antenna is also fabricated. HPMP incidences from the main lobe directions of the sum beam and difference beam are considered. Compared to the microstrip antenna, obvious suppression of HPMPs is observed in the SSPP mono-pulse antenna in different cases, which verifies the better performance to prevent HPMP damages by SSPPs. The proposed technology to suppress HPMPs by using SSPPs can find wide applications in radar and communication systems in the electronic warfare environment. [ABSTRACT FROM AUTHOR]

An efficient improved spectrum integral method (ISIM) is proposed to accelerate the scattering simulation of cuboid object by method of moment (MoM) in multiplanar layered medium (LM). The layered medium Green’s functions (LMGFs) are studied and decomposed into transmission and reflection terms, which hold the translational invariance and reverse translational invariance, respectively. By virtue of the (reverse) translational invariance of LMGF from the uniform square grids on the surface of the cuboid object, most of the coupling between the expanding basis functions and the testing basis functions can be represented by two kinds of submatrices, i.e., the Toeplitz matrix when transmission term is involved, and the conjugate Toeplitz matrix when reflection term is involved. Moreover, the submatrix coupling the expanding/testing basis functions defined on the edges with those defined on the parallel surfaces/edges is also extended to the (conjugate) Toeplitz matrixes. This will significantly alleviate the heavy computation and memory burden from the conventional SIM. With the improved operations on the basis functions associated with the edges of the cuboid object, the proposed ISIM in LM can reach the computational complexity as low as ${O}$ (${N} ^{1.5}$ log(N)) in the matrix vector production, while the computational complexity of matrix filling and the memory requirement are both ${O}$ (${N}^{1.5}$). Moreover, compared with conventional SIM, both theoretical analysis and numerical results demonstrate that the memory requirement and matrix filling time are dramatically decreased. [ABSTRACT FROM AUTHOR]

Learning discriminative and invariant feature representation is the key to visual image categorization. In this article, we propose a novel invariant deep compressible covariance pooling (IDCCP) to solve nuisance variations in aerial scene categorization. We consider transforming the input image according to a finite transformation group that consists of multiple confounding orthogonal matrices, such as the D4 group. Then, we adopt a Siamese-style network to transfer the group structure to the representation space, where we can derive a trivial representation that is invariant under the group action. The linear classifier trained with trivial representation will also be possessed with invariance. To further improve the discriminative power of representation, we extend the representation to the tensor space while imposing orthogonal constraints on the transformation matrix to effectively reduce feature dimensions. We conduct extensive experiments on the publicly released aerial scene image data sets and demonstrate the superiority of this method compared with state-of-the-art methods. In particular, with using ResNet architecture, our IDCCP model can reduce the dimension of the tensor representation by about 98% without sacrificing accuracy (i.e., < 0.5%). [ABSTRACT FROM AUTHOR]

A novel electromagnetic modeling method for multidomain planar layered medium (MD-PLM) by surface integral equation (SIE) is proposed. The MD-PLM refers to the whole space that is separated into multiple PLM volumes, e.g., the infinite-sized PLM background with inserted finite PLM objects or multilayered parallel-plate structures. In the conventional SIE method for this scenario, only the exterior domain is considered as PLM that is modeled by layered medium Green’s functions (LMGFs), while the interior domain is treated by the multidomain homogeneous SIE. However, in this work, the surface equivalence formulation for this special scenario is reestablished by the LMGFs. Then, both the exterior and interior domains are considered as PLM that is modeled by the corresponding LMGFs and SIE in each subdomain. As a result, only the boundary of each sub-PLM domain is required to be discretized rather than the interfaces of each interior medium, which is different from the way in conventional SIE. Consequently, compared with the conventional SIEs, the proposed method can reduce a large quantity of unknowns and significantly increase the efficiency by reducing the memory consumption. By some numerical examples, the performance of this method is evaluated and compared with the conventional methods. The validity and efficiency of the newly proposed method are also well demonstrated in the examples. [ABSTRACT FROM AUTHOR]

A higher order current and charge integral equation (CCIE) approach is developed for accurate electromagnetic scattering analysis of dielectric objects for a wide frequency band, that is from extremely low frequency to microwave frequency. Compared to the conventional CCIE method, its accuracy has been considerably improved by expanding the currents and charges using high-order hierarchical vector basis functions and higher order orthogonal scalar polynomials, respectively. The proposed higher order approach retains whole-frequency-range stability as the traditional low-order counterpart, but characterized with enhanced accuracy and higher convergence rate. Moreover, the consistency of the basis functions’ expansion order in currents and charges is not mandatorily required, which further increase the flexibility in electromagnetic modeling. The scattered fields of penetrable objects are analyzed to validate the effectiveness of this new higher order CCIE, as well as investigate its accuracy, stability, and flexibility. [ABSTRACT FROM AUTHOR]

The multilayered parallel-plate structure (MPPS) is a typical structure in microwave engineering. In numerical simulation, MPPS is usually modeled by an infinitely large planarly layered medium (PLM) to simplify the computation. For a realistic microwave circuit, however, the substrate is always finite in spatial extent, i.e., it is a finite-sized MPPS (FS-MPPS). To address this issue, a novel surface integral equation (SIE) formulation is proposed for the efficient simulation of FS-MPPS. In this article, the surface equivalence principle is first revisited. For the exterior and interior problems, different Green’s functions are utilized. In particular, the common homogeneous-medium Green’s function is used for the exterior homogeneous region, whereas the layered-medium Green’s function (LMGF) is applied for the interior multilayered structure. In this manner, FS-MPPS is no longer directly approximated by the infinite PLM model, but instead, it is modeled accurately by SIE whose integration kernel is derived from PLM. Finally, a PMCHWT SIE is established for the electromagnetic analysis of FS-MPPS. Due to the finite nature of the inner problem, the setting of PLM and LMGF is not unique. This nonuniqueness is studied in theory and verified by numerical simulation. It is revealed that such a nonuniqueness of the setting of the inner problem does not change the uniqueness of the final solution. To validate the proposed approach, a multidomain FS-MPPS and an FS-MPPS with embedded dielectric structures are investigated. Compared with the conventional brute-force SIE methods for FS-MPPS, where all the interfaces of the layered structure should be discretized and assigned with degrees of freedom (DOFs), the proposed method is more succinct and efficient. [ABSTRACT FROM AUTHOR]

A novel hydraulic fracture scattering simulation method in the hydrocarbon diagnosis is developed in this article. The traditional thin dielectric structure-based surface integral equation (TDS-SIE) is adopted for accurate and stable fracture scattering analysis. To improve the low simulation efficiency of conventional TDS-SIE, a higher order TDS-SIE (HO-TDS-SIE) is developed in this article. The junction vector bases are defined to extend TDS-SIE for the branched fractures. Moreover, the matrix normalization method is adopted to improve the conditioning of impedance matrices and accelerate the convergence rate. The excellent performance of this new HO-TDS-SIE solver for complex hydraulic fracture and network is validated by numerical experiments. To best of our knowledge, this is the first time to extend TDS-SIE into higher order scheme for accurate fracture scattering simulation. [ABSTRACT FROM AUTHOR]

IP flow mobility (IFOM) enables a user equipment to offload data traffic at the IP flow level. Although the procedure of IFOM-based flow offloading has been specified by 3GPP, how many IP flows should be offloaded and when offloading should be performed are not defined. Consequently, IP flows may be routed to a target access network that has a strong signal strength but with backhaul congestion or insufficient access capability. In this paper, we propose two algorithms, referred to as proportional offloading (PO) and proportional and preemption-enabled offloading (PPO), respectively, for IP flow offloading in hybrid cellular and wireless local area networks. The PO algorithm decides an optimal proportion of IP flows, which could be offloaded by considering available resources at the target access network. In the PPO algorithm, both service continuity and network utilization are taken into consideration. Furthermore, a detailed analytical model is developed in order to evaluate the behavior of the proposed algorithms. The analytical model is validated through extensive simulations. The results show that by dynamically adjusting the percentage of traffic flows to be offloaded, PO can reduce blocking probability and increase resource utilization. PPO further improves the performance at the cost of slightly higher offloading overhead. [ABSTRACT FROM AUTHOR]

This paper presents a novel accurate and stable current and charge integral equation (CCIE) solver for the low-frequency scattering of penetrable objects in layered medium (LM). To the best of our knowledge, this is the first time to extend CCIE into LM simulations at low frequency. In order to integrate the matrix-friendly LM Green’s functions (LMGFs) into CCIE, we have rederived them to define new quasi-vector/scalar potentials, which are able to annihilate the frequency singularity in the original LMGFs. Moreover, an effective preconditioner is adopted to improve the conditioning of impedance matrices. In comparison with other perconditioners, this method performs much better. The excellent performance of this new CCIE solver is then demonstrated by numerical experiments. [ABSTRACT FROM AUTHOR]

In evolved multimedia broadcast/multicast service (eMBMS), service continuity enables users move from one cell to another without interrupting eMBMS service. Unlike traditional handover in unicast transmission, an user equipment can receive eMBMS service in either unicast or multicast mode. In this paper, we point out a new handover failure problem in eMBMS due to the miss of rekeying information. We first take a close look at the new handover scenarios. We then investigate the problem by using comprehensive mathematical models. Our models provide insights on the new handover problem and introduce theoretical guidelines for mobile operators to design and optimize their networks without wide deployment to save cost and time. Moreover, we propose a solution to combat against the handover failure. Both the simulation and analytical results demonstrate that the impacts of the eMBMS handover failure are reduced significantly. In this paper, we present a systematic way to investigate the handover failure problem in eMBMS. [ABSTRACT FROM AUTHOR]

A novel hybrid method is developed for the flexible and accurate electromagnetic simulation of penetrable objects in a layered medium (LM). In this method, the original complex simulation domain is first divided into several subdomains, following the spirit of divide-and-conquer. Each subdomain is then meshed and solved independently, where nonconformal mesh is inevitable. The Riemann type transmission condition is utilized at the interfaces of each subdomain to correctly exchange information so that the solutions of all subdomains converge rapidly to the real solution of the original problem. More specifically, in our method, the surface integral equation (SIE) combined with the LM Green’s functions (LMGFs) is adopted for the boundary subdomain, while the finite-element method (FEM) and the spectral element method (SEM) are employed for all the other interior dielectric subdomains. The SIE with LMGFs truncates the simulation domain tightly within the object itself, which drastically decreases the number of unknowns. The interior subdomains are modeled by either FEM or SEM, depending on the geometry and material property of each subdomain. To further enhance the simulation capability, higher order approaches are adopted for all the subdomain solvers in this hybrid method. Several numerical examples are demonstrated, where a high convergence and accuracy of this method is observed. This paper will serve as an efficient and flexible simulation tool for the applications of geophysical exploration. [ABSTRACT FROM PUBLISHER]

It is essential to model channel holding time (CHT), cell residence time (CRT), and handoff rate for performance analysis and algorithm evaluation in mobile cellular networks. The problem has been extensively studied in the past for circuit-switched (CS) cellular networks. However, little research has been done on packet-switched (PS) cellular networks. Unlike that a call occupies a dedicated channel during its whole lifetime in CS networks, an active session in PS networks occupies and releases channels iteratively due to discontinuous reception (DRX) mechanism. In this paper, we investigate the key quantities in PS cellular networks. We present a set of comprehensive new models to characterize the quantities and their relationship in PS networks. The models shed light on the relationship between CHT and CRT and handoff rate. The analytical results enable wide applicability in various scenarios and therefore have important theoretical significance. Moreover, the analytical results provide a quick way to evaluate traffic performance and system design in PS cellular networks without wide deployment, which can save cost and time. [ABSTRACT FROM AUTHOR]

In order to directly utilize the dyadic Green’s functions in surface integral equations (SIEs), a novel double-arctan transformation for nearly hypersingular integrals is proposed in this communication. This new transformation is flexible and applicable to nearly hypersingular integrals in the forms of \hat R\hat R/R^3 , \hat R/R^3^^ , and 1/R^3 over the curved surfaces by a fully numerical method. With the help of the sigmoidal transformation to improve the stability of this new singularly handling method, there results an efficient solution for the third-order near-singularity problems in SIEs. Moreover, the proposed method is also effective for the lower orders of the nearly singular integral kernels. With typical testing cases, the performance of this method is fairly evaluated, and its validity and stability is well demonstrated. [ABSTRACT FROM PUBLISHER]

Accurate and efficient prediction of electromagnetic scattering from inhomogeneous objects in layered medium is one of the most challenging issues in engineering applications. This paper presents the first 3-D higher order hybrid finite-element method (FEM) and method of moments (MoM) for the accurate modeling of inhomogeneous dielectric objects in multilayered medium. The main challenges of this paper include: 1) the integration of these algorithms for layered medium and 2) the higher order computational approach involved in layered medium for high efficiency. In the proposed method, the MoM with the layered medium dyadic Green’s function is used as the exact radiation boundary condition in an inhomogeneous background, and the FEM is applied to model the inhomogeneous objects. Furthermore, the higher order maximally orthogonal basis functions with curl-conforming and divergence-conforming properties are used in the FEM and MoM, respectively to improve the modeling capability of this algorithm. For 3-D inhomogeneous objects scattering in multilayered medium, this new method requires a much more tightly truncated simulation domain than the traditional FEM, and provides much higher flexibility than the pure surface integral equation method. Finally, some numerical results are provided to validate the accuracy, efficiency, and flexibility of this method. [ABSTRACT FROM AUTHOR]

A novel radiation-hardened-by-design (RHBD) structure to reduce the single event transient (SET) amplitude in analog circuits is presented in this paper. This structure features an SET isolation technique, which contains a sensor and a switch. The sensor turns off the switch when it detects a voltage transient at the sensitive node, in which case the core circuit is temporarily isolated from the output. Once the voltage at the sensitive node recovers, the sensor turns on the switch again in order to connect the core circuit to the output. This RHBD technique was validated based on a typical bandgap reference circuit, which was fabricated in the IBM 130 nm technology. The simulation results demonstrated a significant reduction in the SET amplitude, which was further verified with the pulsed laser. The additional sensor and the switch in the circuit only produce a minor amount of additional power dissipation if they are properly chosen. The area overhead is rendered negligible by means of selecting the appropriate sizes of transistors for the RHBD structure. [ABSTRACT FROM PUBLISHER]

For perfectly electric conducting (PEC) objects, one difference between the electric-field integral equation (EFIE) and the magnetic-field integral equation (MFIE) is related to the solid angle, which only exists in the latter. In this communication, the correct computation of solid-angle contribution in MFIE is first summarized and clarified. Through testing strictly inside triangles (TSIT) and testing on edges (TOE) with or without the correct limit value (CLV) for the solid-angle integral, six versions of MFIE are then implemented by utilizing Rao–Wilton–Glisson (RWG) functions for expansion and utilizing RWG or rotated Buffa–Christiansen (BC) functions for testing. Based on the simulations of typical sharp-edged targets and a sphere by the EFIE and six MFIEs, it is found that using CLVs for the solid-angle integral will improve the simulation accuracy substantially in comparison to that with incorrect limit values (ILVs). Moreover, if the singularities are properly handled, the MFIE implemented by TSIT can achieve the same accuracy with the MFIE implemented by TOE with CLVs. [ABSTRACT FROM PUBLISHER]

This paper studies how to efficiently apply device-to-device (D2D) communications underlaying a cellular system to support vehicle-to-vehicle (V2V) connection (termed D2D-V). By considering the geographic features of the D2D-V system, we propose a D2D-V grouping, reuse channel selection (RS), and power control (PC) framework to achieve the optimal performance of the D2D-V system, in terms of either maximized sum rate or maximized minimally achievable rate. First, in a full channel state information (CSI) scenario, we apply difference of two convex functions (D.C.) programming to obtain the optimal PC. However, because the CSI between some terminals is hard to obtain and some interference can be appropriately inhibited by taking advantage of the vehicles' geographic features, we make a series of simplifications to the PC problem to reduce the requirement of full CSI, the dependence of centralized control, and the computational complexity. The suitable conditions of each simplification are elaborated. Each step of our simplifications are shown as a certain tradeoff between performance and complexity. Furthermore, we provide an investigation into the service quality that one vehicle can achieve when it passes through the covered segment of the highway and propose the location–service curve to portray this. We use numerical simulations to verify the accuracy and feasibility of each step of our suboptimal PC and specific features embedded in the location–service curve. [ABSTRACT FROM PUBLISHER]

The reliability of circular electrical connectors was usually assessed according to standards like MIL-HDBK-217 (Reliability Prediction of Electronic Equipment). Given to their limitations and mislead results, a new assessment method needs to be presented. Some concerns on the physics of failure (PoF) modeling and reliability assessment of circular electrical connectors are addressed in this paper to overcome this defect. An original approach combining laboratory accelerated degradation testing (ADT) and PoF modeling is proposed for effectively assessing connector reliability. Random vibration and current stress are selected as acceleration factors that affect the contact life of electrical connectors. Then, an appropriate multiple-stresses ADT scheme is derived. The PoF model for electrical connectors under multiple stresses yielded the generalized Eyring relationship. According to the system reliability model for multiposition connectors, connectors’ life follows Weibull distribution, which is derived from extreme-value distribution theory. Through ADT and data gained from tests, statistical analysis result yielded the estimated value of reliability character of MIL-C-38999 I series electrical connectors under the action of vibration and current stresses. [ABSTRACT FROM PUBLISHER]

A new approach for synthesizing wideband frequency-invariant (FI)-shaped patterns is presented. This method is a significant extension of the original iterative spatiotemporal Fourier transform (STFT) method that only deals with wideband FI pencil-beam patterns. Based on the original method, the wideband pattern can be regarded as a spatiotemporal spectral distribution, and the relationship between the spatiotemporal spectral distribution and finite-impulse-response (FIR) filter coefficients can be built as an STFT, which can be efficiently calculated by using 2-D fast Fourier transform (2-D-FFT). To achieve desired FI-shaped pattern performance, the spatiotemporal spectral distribution is iteratively adjusted by two new techniques called wideband pattern shaping and linear phase response (LPR)-based modification. Different from the constant phase response (CPR) processing in the original iterative STFT method, the LPR-based modification uses more relaxed phase requirements, thus releasing much more degrees of freedom. Numerical results show that the proposed method is effective even for very complicated pattern requirements, and it is very efficient in terms of both computation and storage. Besides, the proposed method can take into account the effects of frequency-variant antenna element patterns and mutual coupling in the periodic array structure. [ABSTRACT FROM AUTHOR]

A symmetry relation of the integral operators in a layered medium proved by the reciprocal theory can be applied to improve the accuracy of the magnetic-field integral equation (MFIE). Based on the symmetric layered medium Green’s function, the normal vector can be transferred into the inner integral to keep the field integral as the inner integral of the elements in the impedance matrix. When discretized by the divergence-conforming function, this field-extracted scheme shows better performance than the classic expression in accuracy. Meanwhile, this form of expression can be applied in the combined-field integral equation (CFIE). Several numerical results are provided to validate the formulation of the symmetry relations from the layered medium Green’s function to the impedance matrices and to reveal its advantages in enhancing the accuracy of the field-extracted form of MFIE. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of a current-fed full-bridge boost dc-dc converter with zero-current switching (ZCS), based on the constant on-time control for high-voltage applications. The current-fed full-bridge boost converter can achieve ZCS by utilizing the leakage inductance and parasitic capacitance as the resonant tank. In order to achieve ZCS under a wide load range and with various input voltages, the turn-on time of the boost converter is kept constant, and the output voltage is regulated via frequency modulation. The steady-state analysis and the ZCS operation conditions under various load and input-voltage conditions are discussed. Finally, a laboratory prototype converter with a 22-27-V input voltage and 1-kV/1-kW output is implemented to verify the performance. The experimental results show that the converter can achieve high output voltage gains, and the highest efficiency of the converter is 92% at full-load condition with an input voltage of 27 V. [ABSTRACT FROM AUTHOR]

This letter proposes a novel current-fed parallel-resonant dc-ac inverter with zero-current switching (ZCS) for cold-cathode fluorescent lamps (CCFLs). The leakage inductance of the transformer is integrated within the resonant tank in order to reduce the voltage spikes across the switches. A laboratory prototype is implemented to drive a 617 mm/7W CCFL. Experimental results indicate that the switches of the proposed resonant inverter are operated under the ZCS condition, and the efficiency is approximately 86.8%. The lamp voltage is about 977 Vrms and the lamp current is 7 mArms. [ABSTRACT FROM AUTHOR]

The study and implementation of a single-stage current-fed full-bridge boost converter with power factor correction (PFC) and zero current switching (ZCS) for high voltage application is presented in this paper. The single-stage current-fed full-bridge boost PFC converter can achieve ZCS by utilizing the leakage inductance and parasitic capacitance as the resonant tank. The variable frequency control scheme with ZCS is used to regulate the output voltage and achieve high power factor. The operating principle, steady-state analysis, and control method of this single-stage ac-dc PFC converter are provided. Also, the ZCS operational conditions under various operational conditions are discussed. The design guidelines are given and verified by a laboratory prototype converter with 200 ∼ 240 Vrms input voltage and a 4 kV/1.2 kW output. In order to reduce the switching losses, the highest switching frequency is constrained at 160 kHz. So, the switching frequency of the prototype converter is 50∼460 kHz. The measured power factor is 0.995 and the efficiency is 87.4 at full-load condition with an input voltage of 220 Vrms. The laboratory prototype converter can be operated at ZCS under full range by carefully designing the circuit parameters. [ABSTRACT FROM AUTHOR]

Microwave bandpass filters constructed from materials exhibiting some non-linearity, such as superconductors, will generate intermodulation distortion (IMD) when subjected to signals at more than one frequency. In commercial applications of superconductive receive filters, it is possible for IMD to be generated when a weak receive signal mixes with very strong out-of-band signals, such as those coming from the transmitter. A measurement procedure was developed and data were taken on several different types of superconducting bandpass filters, all developed for commercial application. It was found that in certain interference situations, the three-tone mixing can produce a spur that is noticeable by the receiver, but that there are simple preventative design solutions. [ABSTRACT FROM AUTHOR]

A novel method is presented to efficiently synthesize linearly polarized shaped patterns for antenna arrays mounted on complex platforms surrounded with many scatters. The vectorial active element patterns (Vec. AEPs) are adopted to include the mutual coupling and complex platform effect. The vectorial least-square (LS) active element pattern expansion (Vec. LSAEPE) method is developed to approximate each Vec. AEP as the radiation from a virtual subarray with identical element patterns, so that the fast Fourier transform (FFT) can be utilized to efficiently perform the forward and backward transformations between the excitation distribution and the vectorial array pattern including mutual coupling. An energy-based weighted averaging method is introduced to merge the excitation vectors obtained from copolarization (CoP) and cross-polarization (XP) pattern synthesis in each iteration and consequently the obtained final excitation vector can simultaneously meet both the CoP and XP pattern requirements. The method is called the iterative Vec. LSAEPE-FFT significantly extends the FFT-based synthesis technique to be capable of controlling the CoP main lobe shape, sidelobe distribution, and the XP level. Three examples for synthesizing different shaped patterns for different antenna arrays on complex platforms are conducted to validate the effectiveness of the proposed method. A comparison with some other representative methods is also provided to verify the advantages of the proposed method in both accuracy and efficiency. [ABSTRACT FROM AUTHOR]

Lumen, chromaticity, and correlated color temperature CCT are the three main performance indicators of failure of high-power white light-emitting diodes (LEDs) (HPWLEDs). The existing data-driven (DD) method to predict the life of LEDs often considers that three performance indicators are independent, or only one or two performance indicators are used for prediction, which may not be accurate enough. To solve this problem, a method based on Archimedean Copula function is proposed to describe the correlation of multiple performance indicators. The test data reported from LUXEON is used as an example to establish a 3-D life prediction model by combining the thresholds of three performances to predict the life of LEDs, and the application of Copula function is explained. The results show that there is a little influence on life prediction of LEDs among the different Copula function structures, while the difference between considering single performance and multi-performance is obvious. The mean time to failure (MTTF) of which is proven to be more conservative than the L70 life predicted by the conventional method. [ABSTRACT FROM AUTHOR]

The correlated color temperature (CCT) is one of the performance indicators of color shift failure of the high-power white light-emitting diodes (HPWLEDs). The prognostics for CCT shift of HPWLEDs using deterministic or statistical models usually generate a considerable amount of uncertainties by assuming the degradation model of CCT is a deterministic exponential function, which may not be accurate. To overcome this problem, a stochastic process model based on gamma process is established to present the distribution of CCT maintenance lifetime with the probability density function and the cumulative distribution function. The test data reported from LUXEON was used as an example to demonstrate the utilization of the gamma process model. The mean time to failure of which was proved to be more conservative than the L70 lifetime predicted by the conventional method. The CCT shift appears to have a period of nonmonotonic seasoning stage, whereas the gamma process is only applicable to the monotonic degradation. Aiming at this problem, a unified analytical method was established based on generalized Eyring model to estimate seasoning stage under various conditions. The results of which were proved to be reliable. [ABSTRACT FROM AUTHOR]

We present an efficient nonconformal-mesh discontinuous Galerkin (DG) method for elastic wave propagation in viscous media. To include the attenuation and dispersion due to the quality factor in time domain, several sets of auxiliary ordinary differential equations (AODEs) are added. Unlike the conventional auxiliary partial differential equation-based algorithm, this new method is highly parallel with its lossless counterpart, thus requiring much less time and storage consumption. Another superior property of the AODE-based DG method is that a novel exact Riemann solver can be derived, which allows heterogeneous viscoelastic coupling, in addition to accurate coupling with purely elastic media and fluid. Furthermore, thanks to the nonconformal-mesh technique, adaptive hp-refinement and flexible memory allocation for the auxiliary variables are achieved. Numerical results demonstrate the efficiency and accuracy of our method. [ABSTRACT FROM PUBLISHER]

The single-event transient effect on a ring-oscillator based and an LC-tank based phased-locked loop circuits fabricated in a 0.25 \mum silicon-on-sapphire technology is analyzed with circuit-level simulations followed by laser experiments. Advantages of the LC-tank based circuits in terms of single-event tolerance over the ring-oscillator based circuits are discussed. [ABSTRACT FROM PUBLISHER]

In this paper we propose a design using a guiding system, Radio Frequency Identification (RFID), IEEE 802.15.1 short-range wireless transmission technology and the Internet to fabricate a blood pressure measurement (BPM) which works in cooperation with a health management system. Our design has many advantages, including being easy to use by the aged, low cost and wireless connectivity. It allows the early detection of high blood pressure and provides a doctor with a means for observing a patient's health over a long period. The guiding system provides video guide features for the measuring steps, reminds the patient of the measurement results and makes suggestions. We propose here a new design to determine the BPM posture in order to increase the BPM reliability. [ABSTRACT FROM PUBLISHER]