Beneath Surface Similarity: Large Language Models Make Reasonable Scientific Analogies after Structure Abduction

The vital role of analogical reasoning in human cognition allows us to grasp novel concepts by linking them with familiar ones through shared relational structures. Despite the attention previous research has given to word analogies, this work suggests that Large Language Models (LLMs) often overlook the structures that underpin these analogies, raising questions about the efficacy of word analogies as a measure of analogical reasoning skills akin to human cognition. In response to this, our paper introduces a task of analogical structure abduction, grounded in cognitive psychology, designed to abduce structures that form an analogy between two systems. In support of this task, we establish a benchmark called SCAR, containing 400 scientific analogies from 13 distinct fields, tailored for evaluating analogical reasoning with structure abduction. The empirical evidence underlines the continued challenges faced by LLMs, including ChatGPT and GPT-4, in mastering this task, signifying the need for future exploration to enhance their abilities.Comment: Accepted to EMNLP 2023 (Findings

A Search for Light Fermionic Dark Matter Absorption on Electrons in PandaX-4T

We report a search on a sub-MeV fermionic dark matter absorbed by electrons with an outgoing active neutrino using the 0.63 tonne-year exposure collected by PandaX-4T liquid xenon experiment. No significant signals are observed over the expected background. The data are interpreted into limits to the effective couplings between such dark matter and electrons. For axial-vector or vector interactions, our sensitivity is competitive in comparison to existing astrophysical bounds on the decay of such dark matter into photon final states. In particular, we present the first direct detection limits for an axial-vector (vector) interaction which are the strongest in the mass range from 25 to 45 (35 to 50) keV/c$^2$

Tropical cyclone energy dispersion in a baroclinic model and its associated cyclogenesis

Thesis (Ph.D.)--University of Hawaii at Manoa, 2008.A case study on typhoon Prapiroon (2000) is performed to examine the role of TCED in the following cyclogenesis in nature. Sensitivity experiments suggest that the previous TC would modulate the large-scale environmental circulations, thus affect the formation of its sequential storm.A remarkable asymmetry appears in the perturbation growth of the wave train in the presence of vertical wind shears. That is, an easterly (westerly) wind shear confines the wave to the lower (upper) level. It is suggested that the vertical shear may impact the Rossby wave train development through both the barotropic-baroclinic mode coupling and the modulation of the group velocity by the mean flow through a "Doppler shift effect". The destabilization of Rossby wave train by regional easterly vertical shears has important implications.The 3D Rossby wave energy dispersion of a TC is studied using a baroclinic primitive equation model. The numerical results demonstrate more complex 3D energy dispersion characteristics than 2D barotropic dynamics. A key feature associated with the formation of 3D wave train is a downward propagation of the relative vorticity and kinetic energy. The upper anticyclonic circulation rapidly induces an intense asymmetric outflow jet in the southeast quadrant, which influences the lower-level Rossby wave train formation. On one hand, the outflow jet exerts an indirect effect on the strength of lower-level wave train through changing in TC intensity and structure. On the other hand, it triggers downward energy propagation, which may further enhance the lower level Rossby wave train formation.The interaction between a tropical cyclone and idealized intertropical convergence zone (ITCZ) is investigated. Once a TC develops in the ITCZ region which satisfies barotropic and baroclinic instability, the southeastward energy dispersion from the TC may accelerate ITCZ breakdown, and the interaction between the convective heating and the perturbation circulations may lead to the generation of new tropical cyclone to the east. Through repeating of the above process, a synoptic-scale wave train oriented in the northwest-southeast direction can be generated and self-maintained.Includes bibliographical references (leaves 148-159).Also available by subscription via World Wide Web159 leaves, bound 29 c

Cyclogenesis Simulation of Typhoon Prapiroon (2000) Associated with Rossby Wave Energy Dispersion*

The genesis of Typhoon Prapiroon (2000), in the western North Pacific, is simulated to understand the role of Rossby wave energy dispersion of a preexisting tropical cyclone (TC) in the subsequent genesis event. Two experiments are conducted. In the control experiment (CTL), the authors retain both the previous typhoon, Typhoon Bilis, and its wave train in the initial condition. In the sensitivity experiment (EXP), the circulation of Typhoon Bilis was removed based on a spatial filtering technique of Kurihara et al., while the wave train in the wake is kept. The comparison between these two numerical simulations demonstrates that the preexisting TC impacts the subsequent TC genesis through both a direct and an indirect process. The direct process is through the conventional barotropic Rossby wave energy dispersion, which enhances the low-level wave train, the boundary layer convergence, and the convection–circulation feedback. The indirect process is through the upper-level outflow jet. The asymmetric outflow jet induces a secondary circulation with a strong divergence tendency to the left-exit side of the outflow jet. The upper-level divergence boosts large-scale ascending motion and promotes favorable environmental conditions for a TC-scale vortex development. In addition, the outflow jet induces a well-organized cyclonic eddy angular momentum flux, which acts as a momentum forcing that enhances the upper-level outflow and low-level inflow and favors the growth of the new TC. 1

Lightweight YOLOv7 Algorithm for Multi-Object Recognition on Contrabands in Terahertz Images

With the strengthening of worldwide counter-terrorism initiatives, it is increasingly important to detect contrabands such as controlled knives and flammable materials hidden in clothes and bags. Terahertz (THz) imaging technology is widely used in the field of contraband detection due to its advantages of high imaging speed and strong penetration. However, the terahertz images are of poor qualities and lack texture details. Traditional target detection methods suffer from low detection speeds, misdetection, and omission of contraband. This work pre-processes the original dataset using a variety of image processing methods and validates the effect of these methods on the detection results of YOLOv7. Meanwhile, the lightweight and multi-object detection YOLOv7 (LWMD-YOLOv7) algorithm is proposed. Firstly, to meet the demand of real-time for multi-target detection, we propose the space-to-depth mobile (SPD_Mobile) network as the lightweight feature extraction network. Secondly, the selective attention module large selective kernel (LSK) network is integrated into the output of the multi-scale feature map of the LWMD-YOLOv7 network, which enhances the effect of feature fusion and strengthens the network’s attention to salient features. Finally, Distance Intersection over Union (DIOU) is used as the loss function to accelerate the convergence of the model and to have a better localisation effect for small targets. The experimental results show that the YOLOv7 algorithm achieves the best detection results on the terahertz image dataset after the non-local mean filtering process. The LWMD-YOLOv7 algorithm achieves a detection accuracy P of 98.5%, a recall R of 97.5%, and a detection speed of 112.4 FPS, which is 26.9 FPS higher than that of the YOLOv7 base network. The LWMD-YOLOv7 achieves a better balance between detection accuracy and detection speed. It provides a technological reference for the automated detection of contraband in terahertz images

Design of Suspended Slot Racetrack Microring Refractive Index Sensor Based on Polymer Nanocomposite

Recently, polymer nanocomposites have attracted great interest due to their remarkable characteristics of high performance and enabling production of low-cost devices. This article explores the reflective index sensing application of the polymer nanocomposite IOC-133, which is a TiOx/polymer nanocomposite with a reflective index between 1.8 and 1.9. Considering the material properties of high reflective index, low absorption loss, and compatibility with nanoimprint lithography, a microring-based reflective index sensor with a suspended slot waveguide structure is proposed. We combined the sensing mechanism of slot waveguides with high reflective index polymer nanocomposites and designed the suspended structure to address the problem of decreasing sensitivity caused by residual layers. The sensing device was adopted as a microring resonator, which is conducive to large-scale integration. The finite-difference time-domain (FDTD) method was employed to analyze the effects of several key parameters. The results showed that the racetrack microring sensor we propose can achieve a high sensitivity of 436 nm/RIU (Refractive Index Units), about six times higher than the microring sensor with a ridge waveguide. The Q factor of the microring reaches 1.42 × 104, and the detection limit is 1.38 × 10−4 RIU. The proposed suspended slot microring sensor has potential value in the field of nanoprinted photonic integrated circuits

Measurement of interfacial shear stress in gas–liquid two-phase stratified flow

From Crossref journal articles via Jisc Publications RouterHistory: epub 2023-10-26, issued 2023-10-26, ppub 2023-10-28Publication status: PublishedFunder: National Natural Science Foundation of China; FundRef: https://doi.org/10.13039/10.13039/501100001809; Grant(s): 62173122Funder: Key Project of Natural Science Foundation of Hebei Province; Grant(s): F2021201031Funder: Beijing-Tianjin-Hebei Collaborative Innovation Community Construction Project; Grant(s): 20540301DFunder: Natural Science Foundation of Hebei Province; FundRef: https://doi.org/10.13039/10.13039/501100003787; Grant(s): F2022201034Funder: Hebei Provincial Postgraduate Demonstration Course Project; Grant(s): KCJSX2021009Gas–liquid two-phase stratified flow exists in many industrial processes. Although the flow pattern is simple, the interfacial shear prediction of stratified flow is still the focus of the study. The calculation of the shear stress at the gas–liquid interface is closely related to the measurement of the void fraction and pressure drop of the stratified flow. In this study, a new method for the calculation of interfacial shear stress of gas–liquid two-phase stratified flow is proposed. Differential pressure measurement and planar laser-induced fluorescence technology are combined to obtain important parameters for stratified flow under low-speed flow conditions (Ql = 0.10–0.25 m3/h, Qg = 0.35–1.00 m3/h). The interfacial shear stress is successfully calculated using macroparameters. The uncertainty associated with the calculated parameters using the proposed method is 2.67%, and this study verifies the accuracy of the linear relationship. The method provides a new way to obtain the interfacial shear stress of gas–liquid stratified flow

Highly Sensitive Liquid M-Z Waveguide Sensor Based on Polymer Suspended Slot Waveguide Structure

The slot structure has great advantages in improving the sensitivity of integrated waveguide optical sensors and reducing the detection limit. We propose a polymer Mach–Zehnder interferometer (MZI) optical sensor based on the slot structure and adopted the suspended structure to improve optical field interaction with the analyte, hence boosting the sensor’s sensing accuracy. In this paper, the effects of the single waveguide width, slot width, and coupling structure of the slot waveguide on the performance of the sensor operating at a 1550 nm wavelength were analyzed. Under the premise of satisfying single-mode transmission, we designed an MZI with a branch spacing of 10 µm, arm length of 2045 µm, branch span of 700 µm, and slot region of 500 µm. The sensor’s average sensitivity was 972.1 dB/RIU, and its average detection resolution was 1.6 × 10−6 RIU, which is approximately 1.5 times higher than that of the suspended strip waveguide, 1.6 times higher than that of the non-suspended slot structure, and 2.1 times higher than that of the non-suspended strip waveguide

Spatial Aggregation Net: Point Cloud Semantic Segmentation Based on Multi-Directional Convolution

Semantic segmentation of 3D point clouds plays a vital role in autonomous driving, 3D maps, and smart cities, etc. Recent work such as PointSIFT shows that spatial structure information can improve the performance of semantic segmentation. Motivated by this phenomenon, we propose Spatial Aggregation Net (SAN) for point cloud semantic segmentation. SAN is based on multi-directional convolution scheme that utilizes the spatial structure information of point cloud. Firstly, Octant-Search is employed to capture the neighboring points around each sampled point. Secondly, we use multi-directional convolution to extract information from different directions of sampled points. Finally, max-pooling is used to aggregate information from different directions. The experimental results conducted on ScanNet database show that the proposed SAN has comparable results with state-of-the-art algorithms such as PointNet, PointNet++, and PointSIFT, etc. In particular, our method has better performance on flat, small objects, and the edge areas that connect objects. Moreover, our model has good trade-off in segmentation accuracy and time complexity

Low Power Consumption Hybrid-Integrated Thermo-Optic Switch with Polymer Cladding and Silica Waveguide Core

Taking advantage of the large thermo-optical coefficient of polymer materials, a hybrid-integrated thermo-optic switch was designed and simulated. It is also compatible with the existing silica-based planar light-wave circuit (PLC) platform. To further reduce the power consumption, we introduced the air trench structure and optimized the structural parameters of the heating region. This scheme is beneficial to solving the problem of the large driving power of silica-based thermo-optic switches at this stage. Compared with the switching power of all-silica devices, the power consumption can be reduced from 116.11 mW (TE) and 114.86 mW (TM) to 5.49 mW (TE) and 5.96 mW (TM), which is close to the driving power of the reported switches adopting polymer material as the core. For the TE mode, the switch’s rise and fall times were 121 µs and 329 µs. For the TM mode, the switch times were simulated to be 118 µs (rise) and 329 µs (fall). This device can be applied to hybrid integration fields such as array switches and reconfigurable add/drop multiplexing (ROADM) technology