65 research outputs found
A Compact RFID Reader Antenna for UHF Near-Field and Far-Field Operations
A compact loop antenna is presented for mobile ultrahigh frequency (UHF) radio frequency identification (RFID) application. This antenna, printed on a 0.8 mm thick FR4 substrate with a small size of 31 mm × 31 mm, achieves good impedance bandwidth from 897 to 928 MHz, which covers USA RFID Band (902–928 MHz). The proposed loop configuration, with a split-ring resonator (SRR) coupled inside it, demonstrates strong and uniform magnetic field distribution in the near-field antenna region. Its linearly polarized radiation pattern provides available far-field gain. Finally, the reading capabilities of antenna are up to 56 mm for near-field and 1.05 m for far-field UHF RFID operations, respectively
MatrixVT: Efficient Multi-Camera to BEV Transformation for 3D Perception
This paper proposes an efficient multi-camera to Bird's-Eye-View (BEV) view
transformation method for 3D perception, dubbed MatrixVT. Existing view
transformers either suffer from poor transformation efficiency or rely on
device-specific operators, hindering the broad application of BEV models. In
contrast, our method generates BEV features efficiently with only convolutions
and matrix multiplications (MatMul). Specifically, we propose describing the
BEV feature as the MatMul of image feature and a sparse Feature Transporting
Matrix (FTM). A Prime Extraction module is then introduced to compress the
dimension of image features and reduce FTM's sparsity. Moreover, we propose the
Ring \& Ray Decomposition to replace the FTM with two matrices and reformulate
our pipeline to reduce calculation further. Compared to existing methods,
MatrixVT enjoys a faster speed and less memory footprint while remaining
deploy-friendly. Extensive experiments on the nuScenes benchmark demonstrate
that our method is highly efficient but obtains results on par with the SOTA
method in object detection and map segmentation task
Dense Teacher: Dense Pseudo-Labels for Semi-supervised Object Detection
To date, the most powerful semi-supervised object detectors (SS-OD) are based
on pseudo-boxes, which need a sequence of post-processing with fine-tuned
hyper-parameters. In this work, we propose replacing the sparse pseudo-boxes
with the dense prediction as a united and straightforward form of pseudo-label.
Compared to the pseudo-boxes, our Dense Pseudo-Label (DPL) does not involve any
post-processing method, thus retaining richer information. We also introduce a
region selection technique to highlight the key information while suppressing
the noise carried by dense labels. We name our proposed SS-OD algorithm that
leverages the DPL as Dense Teacher. On COCO and VOC, Dense Teacher shows
superior performance under various settings compared with the pseudo-box-based
methods.Comment: ECCV202
DBQ-SSD: Dynamic Ball Query for Efficient 3D Object Detection
Many point-based 3D detectors adopt point-feature sampling strategies to drop
some points for efficient inference. These strategies are typically based on
fixed and handcrafted rules, making difficult to handle complicated scenes.
Different from them, we propose a Dynamic Ball Query (DBQ) network to
adaptively select a subset of input points according to the input features, and
assign the feature transform with suitable receptive field for each selected
point. It can be embedded into some state-of-the-art 3D detectors and trained
in an end-to-end manner, which significantly reduces the computational cost.
Extensive experiments demonstrate that our method can reduce latency by 30%-60%
on KITTI and Waymo datasets. Specifically, the inference speed of our detector
can reach 162 FPS and 30 FPS with negligible performance degradation on KITTI
and Waymo datasets, respectively
Anisotropic permeability in deterministic lateral displacement arrays
We uncover anisotropic permeability in microfluidic deterministic lateral
displacement (DLD) arrays. A DLD array can achieve high-resolution bimodal
size-based separation of microparticles, including bioparticles, such as cells.
For an application with a given separation size, correct device operation
requires that the flow remains at a fixed angle to the obstacle array. We
demonstrate via experiments and lattice-Boltzmann simulations that subtle array
design features cause anisotropic permeability. Anisotropic permeability
indicates the microfluidic array's intrinsic tendency to induce an undesired
lateral pressure gradient. This can cause an inclined flow and therefore local
changes in the critical separation size. Thus, particle trajectories can become
unpredictable and the device useless for the desired separation task.
Anisotropy becomes severe for arrays with unequal axial and lateral gaps
between obstacle posts and highly asymmetric post shapes. Furthermore, of the
two equivalent array layouts employed with the DLD, the rotated-square layout
does not display intrinsic anisotropy. We therefore recommend this layout over
the easier-to-implement parallelogram layout. We provide additional guidelines
for avoiding adverse effects of anisotropy on the DLD.Comment: 13 pages, 10 figures, 1 table, DLD, particle separation,
microfluidics, anisotropic permeabilit
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