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A novel microfluidic sensor based on quarter-mode localized surface equipartition excitations for liquid detection is proposed in this article. The sensor has a compact size and ultrahigh sensitivity. With the excellent properties of field enhancement and field confinement of the localized surface plasmon (LSP), a double-interdigitated structure is employed to further improve the sensitivity. The proposed sensor is validated in a microwave frequency regime, and the confined electric field is fully employed by placing a microfluidic channel etched on polydimethylsiloxane (PDMS), which is aligned on top of the internal interdigitation. The results show that the simulated results are in good agreement with the experimental measurements. The ultrahigh sensitivity with 0.34% is excited by the addition of interdigitated structure. The ultrahigh sensitivity and compact size make it a good choice for sensing applications, which can be widely used in environmental monitoring, medical health, and other fields and have great potential in the microwave and terahertz regions. [ABSTRACT FROM AUTHOR]

The detection of anomalous paths from floating vehicle trajectories plays an increasingly important role in dynamic path planning because of its ability to identify fraudulent transport behaviors, unexpected traffic accidents, and traffic restriction areas. Existing studies mostly emphasize the significant deviations based on global shape metrics and cannot manage trajectories with missing segments. To address these problems, this study proposes a new sequential pattern mining based method for detecting anomalous paths (SPDAP) in floating vehicle trajectories. First, discrete trajectory points were transformed into consecutive road segment sequences using map matching and essential empirical information. Focusing on these segment sequences, this method constructs a directed graph and calculates the conditional occurrence probabilities of multi-order sub-paths on the graph. On this basis, we designed a sequential pattern mining algorithm by estimating kernel density distributions to adaptively extract multi-order frequent sub-paths. Finally, these anomalous paths can be identified by matching the operations with frequent paths. Comparative experiments on simulated trajectories demonstrated that SPDAP could accurately, adequately, and adaptively detect anomalous paths. Additionally, using real-life taxi trajectories, we conducted semantic analysis by considering travel time and charges to further derive four patterns from the detected anomalous paths. These patterns are expected to support the identification of fraudulent taxi trips and the discovery of candidate driving routes with a preference for saving time or charge. In the future, we will focus on tracing the intrinsic causes of anomalous paths by introducing multisource information and performing real-time anomalous path detection using adaptive time intervals. [ABSTRACT FROM AUTHOR]

This letter proposes two compact folded spoof surface plasmon polariton (SSPP) transmission lines (TL) with single-sided grooves (Type A) and double-sided grooves (Type B), and their cut-off frequencies are 17.55 GHz and 19.52 GHz, respectively. Due to large number of units, the proposed SSPP TLs have steep sideband and excellent upper band suppression (< −48 dB). The compact folding solution could reduce the lateral size to nearly 2/5 of the original one, and to a certain extent solve the layout difficulties associated with traditional SSPP TLs due to their slender structure. The cut-off frequency can be independently regulated by stub length and width. The proposed components are fabricated and tested. The experimental results are in good agreement with the simulated results, demonstrating the possibility of compact folded SSPP TLs and greatly improving the potential of SSPP use in miniaturized and highly integrated circuit systems. [ABSTRACT FROM AUTHOR]

This paper proposes a liquid sensor based on artificial magnetic conductor. The artificial magnetic conductor structure is optimized numerically using particle-ant colony optimization algorithm to increase the freedom of structural optimization exploration while reducing the time consumption. In the optimization process, the resonant frequency is kept at 2.45 GHz to ensure that the operating frequency is within the industrial scientific medical (ISM) band. The optimized artificial magnetic conductor is combined with a broadband antenna to build a liquid sensor. The designed sensor is fabricated and tested by loading butan-1-ol, propan-2-ol, ethanol, methanol, and water. The liquid samples can be injected directly into the channel without the need for additional expensive microfluidic chip such as polydimethylsiloxane, thereby greatly reducing the fabrication cost. A maximum sensitivity of 3.48% and a wide application range up to 78 are achieved, verifying the potential of the proposed sensor for low cost and real time monitoring of liquid samples in practical applications. [ABSTRACT FROM AUTHOR]

Microwave microfluidic sensors have been employed for dielectric characterization of different liquids. Intuitively, the microfluidic channel plays a vital role in determining the sensor performance. In this article, for the first time, numerical optimization design of microfluidic channel route is carried out with the aim of improving the sensor sensitivity. Two swarm intelligence algorithms, i.e., particle-ant colony optimization algorithm and wolf colony algorithm, are implemented for the route optimization. Through the developed optimization procedure, the sensor sensitivity of the original design can be increased significantly. Several prototypes of optimized sensors are fabricated and tested, and they exhibit good capability in retrieving the liquid properties. In comparison with original complementary split-ring resonator-based sensor with a sensitivity of 0.308% for water measurement, the optimized sensor achieves a high sensitivity value of 0.55%, i.e., the sensor sensitivity is increased by 78.6% after optimization. The developed methodology can also be used in other designs, such as series LC-based sensor, whose sensitivity can be improved by about 50%. It is demonstrated that the developed methodology possesses good automatic optimization ability and universality for the optimal design of microwave microfluidic sensors. [ABSTRACT FROM AUTHOR]

In this article, we use an in-house finite element method (FEM)-based parallel computing simulator to model multiphysics processes of resistive random access memories (RRAMs). These RRAMs are based on six different metal oxides, including TiOx, NiOx, HfOx, WOx, ZrOx, and TaOx. In a single RRAM cell, the resistance ratio, reset voltage, reset current, reset power, and temperature are numerically compared. In the RRAM array, the resistance ratio, the minimum feature size (FS) to avoid bit loss, temperature, and oxygen vacancy density are obtained and discussed. The advantages of the six metal oxides-based RRAMs are analyzed based on their physical parameters, including diffusivity, electrical conductivity, and thermal conductivity. Numerical results reveal that thermal crosstalk effects are more severe when the FSs decrease, even the inactive cell can be transferred from a low-resistance state (LRS) into a high-resistance state (HRS). A crossbar array with a diamond heat sink is proposed to suppress the thermal crosstalk effect. [ABSTRACT FROM AUTHOR]

Automatic optimization of resonant structure is highly desired in the design of high-sensitivity microwave microfluidic sensors. In this paper, the design of resonant structures is abstracted as a decision model, and a deep deterministic policy gradient algorithm based on joint simulation is applied to achieve automatic optimal design through a learned strategy. The agent’s action strategy is decomposed into multiple movement actions against the pixelated structure and finally outputs the optimized structure. Through the optimal structure adjustment strategy, the sensor sensitivity can be dramatically improved. Depending on the design requirement, the liquid consumption volume can be set to be a constant or variable. To evaluate the performance of the proposed strategy, two optimized prototypes are prepared and tested. Compared with the original complementary split-ring resonator-based sensor which obtains a sensitivity of 0.522% for water measurement, the optimized sensors achieve high sensitivities of 0.666% and 0.805%, respectively, implying that the deep deterministic policy gradient-based agent can effectively explore the optimization strategy. This study is a meaningful attempt to develop automatic design procedure for planar microwave microfluidic sensors. [ABSTRACT FROM AUTHOR]

In this article, a large-scale electromagnetic-thermal-mechanical co-simulation solver is implemented, to simulate complex radio frequency components by using a high performance computing framework. The proposed solver integrates the frequency-domain electric field simulation, with time-domain thermal and thermal-induced stress simulations, via a multiphysics coupling iterative process. In order to speed up the cosimulation, a Krylov subspace method with a domain decomposition method (DDM) preconditioner is used. First, the developed multiphysics solver is verified with the commercial software COMSOL Multiphysics. Then, the parallel performance of our cosimulation solver, with different ghost mesh thicknesses, is tested on a supercomputer. Finally, some multiphysics results of filters and a real-world system-in-package (SiP) are obtained with our proposed solver. [ABSTRACT FROM AUTHOR]

This article presents the construction and analysis of a hybrid numerical method for the discretization of the convection-dominated nonlinear carrier transport process in semiconductor devices. In the construction of the method, the edge streamline upwind (SU) current density model is employed to overcome the nonconvergence brought by the nonlinear property of the current continuity equation, and the mixed finite volume-finite element method (FVFEM) is utilized to effectively extend the edge SU current density model to multidimensional applications. The proposed method is more reliable and flexible than the finite box (FB) method and streamline upwind Petrov–Galerkin (SUPG) method. The performance of several popular SU current density models is compared to find the optimal one. The proposed method is validated by comparing the calculated results with those calculated using commercial software. Based on the streamline upwind-finite volume-finite element method (SU-FVFEM), the finite element method (FEM), and the domain decomposition method (DDM), an in-house parallel computing electrothermal simulator is developed for large-scale semiconductor devices. The performance of the in-house developed parallel simulator is evaluated through simulations of a p-n junction diode and a 3-D bipolar transistor. The results demonstrated that the developed parallel simulator possesses good accuracy, applicability, and scalability. [ABSTRACT FROM AUTHOR]

The paper proposes a temperature-compensated sensor for microfluidic application. The sensor consists of a splitter/combiner section with two symmetrical complementary split-ring resonators (CSRR). A polydimethylsiloxane substrate is attached with the microfluidic channel aligned to the meander slot of the CSRR. A split-ring resonator (SRR) with peripheral circuit is added to detect environmental temperature. The water-methanol mixtures with various water fractions are measured at temperature ranging from 20°C to 50°C. The environmental temperature is firstly measured by the resonant frequency shift produced by SRR. Then, the variations in the resonant frequency and quality factor of the differential splitter/combiner section, as well as the temperature, are used as the input data for training the neural network. In comparison with previous designs, the proposed sensor is capable of not only suppressing the influences of environmental factors, but also retrieving the permittivity and loss tangent of liquid sample at specific temperature, thereby identifying the liquid accurately. [ABSTRACT FROM AUTHOR]