This paper presents a novel kind of patch antenna with high-selectivity filtering responses and high-gain radiation performance. The proposed antenna is mainly composed of a driven patch and a ...stacked patch, with its entire height being 0.09λ. Three shorting pins and a U-slot are embedded in the driven patch to enhance out-of-band suppression levels and skirt selectivity near the lower band-edge, whereas the stacked patch provides a sharp roll-off rate at the upper band-edge and also an enhanced gain. Without using extra filtering circuits, the proposed antenna exhibits a quasi-elliptic boresight gain response with three radiation nulls. For demonstration, an antenna is implemented covering the LTE band (2.3-2.7 GHz). The antenna achieves an average gain of 9.7 dBi within passband, and out-of-band suppression levels of more than 21 dB.
The present paper reviews the novel area of composite to composite and composite to metal joining, utilizing novel 3D reinforcement technology. The 3D reinforcement pinned technology extends the use ...of micro-pins from through-the-thickness laminate reinforcement to joints, while introducing AM (Additive Manufacture) and CMT (Cold Metal Transfer) technologies to the joint research field. The great advantages that this novel joining technique provides are lightweight connection, increased strength and significant improvement in damage tolerance. However, the concept has not been extensively explored in all loading nor environmental conditions and on the effects of the various design and manufacturing parameters.
A new gain-enhanced patch antenna with loading of shorting pins is proposed in this paper. Four metallic pins are symmetrically placed in the two diagonals of a square patch resonator to electrically ...short the patch and ground plane. These shorting pins tremendously perturb the field distribution beneath the patch due to their shunt inductive effect. As these four pins are moved outward along the two orthogonal diagonals away from the center, their influence on the field distribution over the patch is strengthened to gradually raise its dominant mode, i.e., TM010 mode, resonant frequency as the pin-to-pin spacing is enlarged. At a fixed resonant frequency, the overall area of this proposed patch antenna with four pins results to be increased. As such, its radiation directivity or gain gets to be enhanced due to the enlarged antenna area. After extensive analysis is executed, two square patch antennas with and without loaded pins are designed and fabricated. The simulated and measured results agree with each other, and they have evidently demonstrated that the radiation directivity can be enhanced up to 11.0 dBi, or about 2.9 dB increment, by virtue of the proposed approach.
With the advances in microfluidics, electrowettingon-dielectric (EWOD) chips have widely been applied to various biological and chemical laboratory protocols. Glass-based EWOD chips with non-regular ...electrodes are proposed, which allow more reliable droplet operations and facilitate the integration of optical sensors for many biochemical applications. Furthermore, non-regular electrode designs are utilized in EWOD chips, e.g., interdigitated electrodes for more reliable droplet manipulation, custom shaped electrodes for specific applications like concentric heating, etc. However, due to the technical challenges of fabricating multi-layer interconnection on the glass substrate, e.g., unreliable process and high cost, both control electrodes and wires are fabricated with a single-layer configuration, which poses significant challenges to pin selection for non-regular electrodes. In this paper, we propose a minimum-cost flow-based routing algorithm called NR-Router+ that features efficient and robust routing for single-layer EWOD chips with non-regular electrodes. To the best of our knowledge, this is the first work that overcomes the aforementioned challenges. We construct a minimum-cost flow algorithm to generate optimal routing paths followed by a light-weight model to handle flow capacity. A grid reduction strategy is proposed to reduce the computational overhead. Additionally, a flow collocation algorithm based on integer linear programming is presented to efficiently prevent wire overlapping. Experimental results show that NR-Router+ achieves 100% routability while minimizing wirelength with shorter run time. Moreover, NR-Router+ can generate mask files feasible for manufacturing via adjustments of design parameters, thus demonstrating its robustness and efficiency.
Split pins (SPs) play an important role in fixing joint components on catenary support devices (CSDs) of high-speed railway. The occurrence of loose and missing defects of SPs could make the ...structure of CSDs unstable. In this paper, we present a three-stage automatic defect inspection system for SPs mainly based on an improved deep convolutional neural network (CNN), which is called PVANET++. First, SPs are localized by PVANET++ and the Hough transform & Chan-Vese model, and then, three proposed criteria are applied to detect defects of SPs. In PVANET++, a new anchor mechanism is applied to produce suitable candidate boxes for objects, and multiple hidden layer features are combined to construct discriminative hyperfeatures. The performance of PVANET++ and several recent state-of-the-art deep CNNs is compared in a data set that is collected from a 60-km rail line. The results show that our model is superior to others in accuracy, and has a considerable speed.
A patch antenna with loading of slot and shorting pins is proposed in this paper to enhance the radiation gain without increasing the patch size. At first, a straight slot is transversely introduced ...in the central line of a patch. For the dominant TM01 mode, this central line behaves as a virtual electric wall with zero electric field and maximum surface current underneath and on the patch, respectively. By doing so, the central slot serves as an extra radiator so that this slot-loaded patch produces radiation as an equivalent three-slot array. Meanwhile, a pair of shorting pins is longitudinally placed at the two symmetrical sides of this central slot to maintain the resonant frequency. Due to the out of phase between the electric fields in the central slot and two sided slots, the far-field radiated by the three slots can be canceled with each other in specific directions away from broadside. Thus, this cancellation results in sidelobe of low level in the E-plane due to emergence of radiation nulls, and further makes the main radiation beam more directionally selective. Accordingly, the directivity and gain of this proposed patch antenna are enhanced with no need of enlarging the overall size of patch. Finally, the simulated and measured results are provided to validate the operating principle and show that the directivity is increased by about 1.7 dB increment.
Thermal stress developed in thermoelectric generators is critical for long service applications. High temperature gradients, due to a large temperature difference across the junctions, causes ...excessive stress levels developed in the device pins and electrodes at the interfaces. In the present study, a thermoelectric generator with horizontal pin configuration is considered and thermal stress analysis in the device is presented. Ceramic wafer is considered to resemble the high temperature plate and copper electrodes are introduced at the pin junctions to reduce the electrical resistance between the pins and the high and low temperature junction plates during the operation. Finite element code is used to simulate temperature and stress fields in the thermoelectric generator. In the simulations, convection and radiation losses from the thermoelectric pins are considered and bismuth telluride pin material with and without tapering is incorporated. It is found that von Mises stress attains high values at the interface between the hot and cold junctions and the copper electrodes. Thermal stress developed in tapered pin configuration attains lower values than that of rectangular pin cross-section.
•Different cold junction temperatures improves thermoelectric generator performance.•von Mises stress remains high across copper electrodes and hot junction ceramics.•von Mises stress reduces along pin length towards cold junction.•Pin tapering lowers stress levels in thermoelectric generator.
A single-fed microstrip patch antenna (MPA) with loading of shorting pins for high-gain circularly polarized (CP) radiation is proposed in this paper. Two sets of metallic pins are symmetrically ...placed along the two orthogonal diagonals of a square patch radiator at first. Due to the shunt inductive effect brought by these shorting pins, the resonant frequency of the dominant mode in this MPA is progressively tuned up so as to enlarge the electrical size of this pin-loaded patch resonator and to enhance its radiation directivity. After the optimal loading position is investigated for maximum directivity of linear polarization, one pair of the inner pins is slightly shifted in an offset to properly separate the two degenerate modes, so that the CP radiation can be excited. Moreover, upon request, either left-handed or right-handed circular polarization can be obtained by means of different position-offset scheme of the inner pins along the diagonals. After extensive analysis is executed, two equal-size CP MPAs with and without shorting pins are fabricated and tested. Simulated and measured results show good agreement and demonstrate that the CP directivity is enhanced from 8.0 (conventional MPA) to 10.8 dBic, indicating a 2.8-dB increment by means of the proposed approach.
The optimal shape of a Plate-Pin-Fin Heat Sink with Perforations and Splitters (PPFHS-PS) is designed in this work using the software package CFD-ACE+ and the Levenberg-Marquardt method (LMM) to ...determine the maximum thermal performance factor η under a fixed fin volume constraint. In the present work, the implementations of perforations and splitters on a pin fin are examined, and the diameter of the pin, the perforated diameter of the pin and the length of the splitter are considered as the design variables. The hydrothermal performances of a Plate-Pin-Fin Heat Sink (PPFHS), a Plate-Pin-Fin Heat Sink with Perforations (PPFHS–P) and a Plate-Pin-Fin Heat Sink with Splitters (PPFHS–S) are compared. It is found that a great enhancement in the thermal performance factor can be resulted for the PPFHS-PS. The numerical design cases indicated that when considering an incoming velocity of 5.0 m/s, the percentage improvements of η for the PPFHS-P, PPFHS-S and design #2 PPFHS-PS are 4.9%, 5.2% and 10.1% higher than that of the original PPFHS. It indicates that the individual contribution of thermal performance factor improvement of the PPFHS-P and PPFHS-S can be added if the perforations and splitters are utilized simultaneously in the PPFHS-PS design. Finally, experimental verifications are conducted on the manufactured PPFHS-P, PPFHS-S and design #2 PPFHS-PS modules, and the measurement results of the temperature distributions and pressure drops indicate that the experimental data matched quite well with the computational data for those heat sinks.
Deep neural networks have attained remarkable performance when applied to data that comes from the same distribution as that of the training set, but can significantly degrade otherwise. Therefore, ...detecting whether an example is out-of-distribution (OoD) is crucial to enable a system that can reject such samples or alert users. Recent works have made significant progress on OoD benchmarks consisting of small image datasets. However, many recent methods based on neural networks rely on training or tuning with both in-distribution and out-of-distribution data. The latter is generally hard to define a-priori, and its selection can easily bias the learning. We base our work on a popular method ODIN, proposing two strategies for freeing it from the needs of tuning with OoD data, while improving its OoD detection performance. We specifically propose to decompose confidence scoring as well as a modified input pre-processing method. We show that both of these significantly help in detection performance. Our further analysis on a larger scale image dataset shows that the two types of distribution shifts, specifically semantic shift and non-semantic shift, present a significant difference in the difficulty of the problem, providing an analysis of when ODIN-like strategies do or do not work.
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