ProxyDet: Synthesizing Proxy Novel Classes via Classwise Mixup for Open-Vocabulary Object Detection

Open-vocabulary object detection (OVOD) aims to recognize novel objects whose categories are not included in the training set. In order to classify these unseen classes during training, many OVOD frameworks leverage the zero-shot capability of largely pretrained vision and language models, such as CLIP. To further improve generalization on the unseen novel classes, several approaches proposed to additionally train with pseudo region labeling on the external data sources that contain a substantial number of novel category labels beyond the existing training data. Albeit its simplicity, these pseudo-labeling methods still exhibit limited improvement with regard to the truly unseen novel classes that were not pseudo-labeled. In this paper, we present a novel, yet simple technique that helps generalization on the overall distribution of novel classes. Inspired by our observation that numerous novel classes reside within the convex hull constructed by the base (seen) classes in the CLIP embedding space, we propose to synthesize proxy-novel classes approximating novel classes via linear mixup between a pair of base classes. By training our detector with these synthetic proxy-novel classes, we effectively explore the embedding space of novel classes. The experimental results on various OVOD benchmarks such as LVIS and COCO demonstrate superior performance on novel classes compared to the other state-of-the-art methods. Code is available at https://github.com/clovaai/ProxyDet.Comment: Accepted in AAAI24. Code: https://github.com/clovaai/ProxyDet Project page: https://proxydet.github.i

Reduced-Size Series-Fed Two-Dipole Endfire Antenna

The conventional series-fed endfire dipole antenna has a wide impedance bandwidth and is inexpensive to manufacture. However, it has a disadvantage: its size is large because of the large inter-dipole spacing, which is required to satisfy the endfire condition for good antenna radiation characteristics. Here, we propose a two-dipole endfire antenna with a reduced size. The miniaturized endfire antenna was designed using a meander line to reduce the interdipole spacing while ensuring that the endfire condition was satisfied. Furthermore, the overall width of the antenna was reduced using a bent dipole and a corrugated ground plane. The electrical size of the proposed antenna was only 0.33λo × 0.33λo × 0.014λo at a center frequency of 5 GHz, its −10 dB impedance bandwidth was 4.47–5.72 GHz (24.5%), and the gain at the center frequency was 5.9 dBi

Effects of Split Position on the Performance of a Compact Broadband Printed Dipole Antenna with Split-Ring Resonators

This paper presents the effects of the position of the split of a split-ring resonator (SRR) on the performance of a composite broadband printed dipole antenna. The antenna is made of two printed dipole arms enclosed by two rectangular and identically printed SRRs. One dipole arm and the SRR are printed on the top side of the substrate, while the other dipole arm and SRR are printed on the bottom side of the same substrate. By changing the position of the split on the SRR, different antenna characteristic values are obtained, namely, for impedance bandwidth and radiation patterns. The split position is thus a critical parameter in antenna design, because it influences the antenna’s major performance immensely. Different split positions and their consequences for antenna performance are demonstrated and discussed. The antenna generates linearly polarized radiations, and it is computationally characterized for broadband characteristics. The optimized compact antenna has overall dimensions of 9.6 mm × 74.4 mm × 0.508 mm (0.06λ × 0.469λ × 0.0032λ at 1.895 GHz) with a measured fractional bandwidth of 60.31% (1.32 to 2.46 GHz for |S 11| 88%

How do caregivers of children with congenital heart diseases access and navigate the healthcare system in Ethiopia?

Background Surgery can correct congenital heart defects, but disease management in low- and middle-income countries can be challenging and complex due to a lack of referral system, financial resources, human resources, and infrastructure for surgical and post-operative care. This study investigates the experiences of caregivers of children with CHD accessing the health care system and pediatric cardiac surgery. Methods A qualitative study was conducted at a teaching hospital in Ethiopia. We conducted semi-structured interviews with 13 caregivers of 10 patients with CHD who underwent cardiac surgery. We additionally conducted chart reviews for triangulation and verification. Interviews were conducted in Amharic and then translated into English. Data were analyzed according to the principles of interpretive thematic analysis, informed by the candidacy framework. Results The following four observations emerged from the interviews: (a) most patients were diagnosed with CHD at birth if they were born at a health care facility, but for those born at home, CHD was discovered much later (b) many patients experienced misdiagnoses before seeking care at a large hospital, (c) after diagnosis, patients were waiting for the surgery for more than a year, (d) caregivers felt anxious and optimistic once they were able to schedule the surgical date. During the care-seeking journey, caregivers encountered financial constraints, struggled in a fragmented delivery system, and experienced poor service quality. Conclusions Delayed access to care was largely due to the lack of early CHD recognition and financial hardships, related to the inefficient and disorganized health care system. Fee waivers were available to assist low-income children in gaining access to health services or medications, but application information was not readily available. Indirect costs like long-distance travel contributed to this challenge. Overall, improvements must be made for district-level screening and the health care workforce.This research was funded by the JW LEE Center for Global Medicine of Seoul National University College of Medicine, Seoul, the Republic of Korea

Search for the Sagittarius Tidal Stream of Axion Dark Matter around 4.55 μ\mueV

We report the first search for the Sagittarius tidal stream of axion dark matter around 4.55 $\mu$eV using CAPP-12TB haloscope data acquired in March of 2022. Our result excluded the Sagittarius tidal stream of Dine-Fischler-Srednicki-Zhitnitskii and Kim-Shifman-Vainshtein-Zakharov axion dark matter densities of $\rho_a\gtrsim0.184$ and $\gtrsim0.025$ GeV/cm$^{3}$, respectively, over a mass range from 4.51 to 4.59 $\mu$eV at a 90% confidence level.Comment: 6 pages, 7 Figures, PRD Letter accepte

The Role of Heart-Rate Variability Parameters in Activity Recognition and Energy-Expenditure Estimation Using Wearable Sensors

Human-activity recognition (HAR) and energy-expenditure (EE) estimation are major functions in the mobile healthcare system. Both functions have been investigated for a long time; however, several challenges remain unsolved, such as the confusion between activities and the recognition of energy-consuming activities involving little or no movement. To solve these problems, we propose a novel approach using an accelerometer and electrocardiogram (ECG). First, we collected a database of six activities (sitting, standing, walking, ascending, resting and running) of 13 voluntary participants. We compared the HAR performances of three models with respect to the input data type (with none, all, or some of the heart-rate variability (HRV) parameters). The best recognition performance was 96.35%, which was obtained with some selected HRV parameters. EE was also estimated for different choices of the input data type (with or without HRV parameters) and the model type (single and activity-specific). The best estimation performance was found in the case of the activity-specific model with HRV parameters. Our findings indicate that the use of human physiological data, obtained by wearable sensors, has a significant impact on both HAR and EE estimation, which are crucial functions in the mobile healthcare system

Design of a broadband circularly polarised uniplanar crossed-dipole antenna

Abstract This study presents the design of a uniplanar crossed-dipole antenna with broadband characteristics. The antenna comprises a pair of identical crossed-dipole arms printed on the same plane of a dielectric substrate. The crossed-dipole arms are corner-cut fat dipoles that are perpendicular to each other and connected with a bent stripline to generate circularly polarised (CP) radiations. A wide dipole arm was used to improve impedance matching and widen the axial ratio (AR) bandwidth. Additionally, the corner of each dipole arm was cut into a triangular shape to broaden the impedance and AR bandwidths further. The antenna in free space is excited via a wideband microstrip-to-parallel stripline tapered balun to reduce the effect of leakage current on the coaxial cable. Experiments and full-wave electromagnetic simulations were employed to design, verify, and validate the antenna design. The antenna, having an overall size of 45 × 45 × 0.508 mm3 (0.4 × 0.4 × 0.0045 λL 3 where λL is the lowest frequency in the 3-dB AR bandwidth), demonstrates the following measured performances: an |S11|< − 10 dB impedance bandwidth of 2.53–9.14 GHz (113.3%), a 3 dB AR bandwidth of 2.65–7.75 GHz (98.1%), and peak gain of 3.7 dBic at 6.6 GHz