Abstract
The ferromagnetic phase of Co
3
Sn
2
S
2
is widely considered to be a topological Weyl semimetal, with evidence for momentum-space monopoles of Berry curvature from transport and ...spectroscopic probes. As the bandstructure is highly sensitive to the magnetic order, attention has focused on anomalies in magnetization, susceptibility and transport measurements that are seen well below the Curie temperature, leading to speculation that a “hidden” phase coexists with ferromagnetism. Here we report spatially-resolved measurements by Kerr effect microscopy that identify this phase. We find that the anomalies coincide with a deep minimum in domain wall (DW) mobility, indicating a crossover between two regimes of DW propagation. We demonstrate that this crossover is a manifestation of a 2D phase transition that occurs within the DW, in which the magnetization texture changes from continuous rotation to unidirectional variation. We propose that the existence of this 2D transition deep within the ferromagnetic state of the bulk is a consequence of a giant quality factor for magnetocrystalline anisotropy unique to this compound. This work broadens the horizon of the conventional binary classification of DWs into Bloch and Néel walls, and suggests new strategies for manipulation of domain walls and their role in electron and spin transport.
This study prognoses the remaining useful life of a turbofan engine using a deep learning model, which is essential for the health management of an engine. The proposed deep learning model affords a ...significantly improved accuracy by organizing networks with a one-dimensional convolutional neural network, long short-term memory, and bidirectional long short-term memory. In particular, this paper investigates two practical and crucial issues in applying the deep learning model for system prognosis. The first is the requirement of numerous sensors for different components, i.e., the curse of dimensionality. Second, the deep neural network cannot identify the problematic component of the turbofan engine due to its “black box” property. This study thus employs dimensionality reduction and Shapley additive explanation (SHAP) techniques. Dimensionality reduction in the model reduces the complexity and prevents overfitting, while maintaining high accuracy. SHAP analyzes and visualizes the black box to identify the sensors. The experimental results demonstrate the high accuracy and efficiency of the proposed model with dimensionality reduction and show that SHAP enhances the explainability in a conventional deep learning model for system prognosis.
Data communication based on white light generated using a near-ultraviolet (NUV) laser diode (LD) pumping red-, green-, and blue-emitting (RGB) phosphors was demonstrated for the first time. A ...III-nitride laser diode (LD) on a semipolar (2021¯) substrate emitting at 410 nm was used for the transmitter. The measured modulation bandwidth of the LD was 1 GHz, which was limited by the avalanche photodetector. The emission from the NUV LD and the RGB phosphor combination measured a color rendering index (CRI) of 79 and correlated color temperature (CCT) of 4050 K, indicating promise of this approach for creating high quality white lighting. Using this configuration, data was successfully transmitted at a rate of more than 1 Gbps. This NUV laser-based system is expected to have lower background noise from sunlight at the LD emission wavelength than a system that uses a blue LD due to the rapid fall off in intensity of the solar spectrum in the NUV spectral region.
The authors present a classical polynomial‐time attack against the branching program obfuscator of Fernando–Rasmussen–Sahai (for short FRS, Asiacrypt’17) (with one zerotest parameter), which is ...robust against all known classical cryptanalyses on obfuscators when instantiated with the CLT13 multilinear map. The first step is to recover a plaintext modulus of the CLT13 multilinear map. To achieve the goal, the Coron and Notarnicola (Asiacrypt’19) algorithm is applied. However, because of parameter issues, the algorithm cannot be used directly. In order to detour the issue, the authors convert an FRS obfuscator into a new programme containing a small message space. Through the conversion, the authors obtain two zerotest parameters and encodings of zero except for two non‐zero slots. Then, they are used to mitigate parameter constraints of the message space recovering algorithm. Then, a cryptanalysis of the FRS obfuscation based on the recovered message space is proposed. The authors show that there exist two functionally equivalent programmes such that their obfuscated programmes are computationally distinguishable. Thus, the FRS scheme does not satisfy the desired security without any additional constraints.
This paper proposes a microarchitectural mechanism to minimize the latency of thread migration for a tightly-coupled heterogeneous core, which has two execution backends (e.g., in-order and ...out-of-order execution pipelines). The proposed mechanism examines the dependencies between all in-flight instructions that reside in one of the backend pipelines, and allows both pipelines to simultaneously perform the instruction execution. At the microarchitectural level, instruction dispatching and instruction execution are seamlessly performed across thread migration, and therefore, this simultaneous backend execution can accelerate the program execution, which cannot be achieved with an existing migration mechanism. Accelerating thread migration will increase the overall performance with low power overhead, providing high energy efficiency. As compared to a baseline heterogeneous core with an existing migration mechanism, the simultaneous backend execution reduces 8.2 percent of the total execution cycle and consumes 2.9 percent lower total energy on average across SPEC CPU2006 benchmarks, which results in an improved energy efficiency of 10.9 percent in terms of the energy-delay product.
Abstract
This paper examines whether the influx of Japanese establishments in colonial Korea during the 1930s suppressed the entry of Korean establishments. We construct new subsector–county-level ...panel data to exploit variations across counties within subsectors. We find that Korean entry rates were higher in counties with a higher presence of Japanese establishments. However, the spillover effects do vary across subsectors, and we find suggestive evidence of negative impacts of Japanese presence in subsectors with more large-scaled establishments. Taken together, Japanese establishments did seem to raise entry barriers in some subsectors but also functioned as a catalyst for Korean entry in other subsectors.
This paper presents the broadband antenna for the microwave radiometric sensing of internal body temperature. For broadband operation, the bow-tie antenna was designed and backed with a cylindrical ...cavity, which decreased environmental electromagnetic interference and also improved the directivity of the antenna. The broadband impedance-transforming balun in microstrip form was also designed to feed the bow-tie antenna, and was located inside the cavity. An impedance-matching dielectric layer (IMDL) was introduced on top of the bow-tie antenna, for impedance match with the human body with high permittivity. The fabricated antenna was measured in free space with the IMDL removed, showing an input reflection coefficient lower than -10 dB from 2.64 to > 3.60 GHz with antenna gain over 6.0 dBi and radiation efficiency over 74.7% from 2.7 to 3.5 GHz. The IMDL was re-installed on the cavity-backed bow-tie antenna to measure the antenna performance for the human head with relative permittivity of about 40. The measured reflection coefficient was as low as -28.9 dB at 2.95 GHz and lower than -10 dB from 2.65 to > 3.5 GHz. It was also shown that the designed antenna recovered a good impedance match by adjusting the permittivity and thickness of the IMDL for the different parts of the human body with different permittivities.
A trimer of dicyanoaurate has been studied as a model system of the covalent chemical bond formation. Here, we report the dynamics of dicyanoaurate trimer in water upon photoexcitation by femtosecond ...time-resolved luminescence (TL) and luminescence spectra at cyrogenic temperature. Temperature was varied as a means to control the medium flexibility as well as the population of isomers. A unique parallelism between the luminescence spectrum vs. time and vs. temperature was observed, which enables unambiguous luminescence band assignments and facilitates investigation of the dynamics. Upon photoexcitation to S1, intersystem crossing proceeds in an ultrafast manner within 20 fs due to the large spin–orbit coupling followed by a structural change from a loose bent to a tight linear form in 1.5 ps. Higher oligomerization occurs above the melting temperature. TL reveals a strong coherent excitation of the symmetric Au–Au stretching vibration at 74 cm–1 through the non-Condon effect.
Visual homing navigation has been a challenging issue in indoor localization and navigation. Inspired by insect navigation, the snapshot model was introduced for homing navigation, where a pair of ...snapshots at the current location and at the nest are compared to guide the homing direction. We investigate Haar-like features in vision to extract visual cues, based on the snapshot model. The Haar-like features consist of masks randomly generated over the snapshot image at the home location, and later, their matching scores at the snapshot available at the current location are calculated for the correspondence measure. We draw landmark vectors using the correspondence measure of Haar-like features at their angular positions. Interestingly, a collection of Haar-like features provide visual characteristics to reflect a pair of snapshot images, which can determine the homing direction. In this paper, we propose two types of homing methods based on the image difference using Haar-like features, the Haar-like landmark vector model and the Haar-like image distance model. We demonstrate the effectiveness of the methods in several environments.
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