588 research outputs found

    A Few-Shot Learning-Based Siamese Capsule Network for Intrusion Detection with Imbalanced Training Data

    Get PDF
    Network intrusion detection remains one of the major challenges in cybersecurity. In recent years, many machine-learning-based methods have been designed to capture the dynamic and complex intrusion patterns to improve the performance of intrusion detection systems. However, two issues, including imbalanced training data and new unknown attacks, still hinder the development of a reliable network intrusion detection system. In this paper, we propose a novel few-shot learning-based Siamese capsule network to tackle the scarcity of abnormal network traffic training data and enhance the detection of unknown attacks. In specific, the well-designed deep learning network excels at capturing dynamic relationships across traffic features. In addition, an unsupervised subtype sampling scheme is seamlessly integrated with the Siamese network to improve the detection of network intrusion attacks under the circumstance of imbalanced training data. Experimental results have demonstrated that the metric learning framework is more suitable to extract subtle and distinctive features to identify both known and unknown attacks after the sampling scheme compared to other supervised learning methods. Compared to the state-of-the-art methods, our proposed method achieves superior performance to effectively detect both types of attacks

    Ultrasonic frogs show extraordinary sex differences in auditory frequency sensitivity

    Get PDF
    Acoustic communication plays an important role in the reproductive behavior of anurans. Males of concave-eared torrent frog (_Odorrana tormota_) have ultrasonic communication capacity 1, 2, but it is unknown whether females communicate with ultrasound. Here we show that _O. tormota_ exhibits great sex differences in the auditory frequency sensitivity. Acoustic playback experiments demonstrated that the male's advertisement calls evoke gravid females' positive phonotaxis and vocal responses, whereas ultrasonic components of the male's calls (frequencies above 20 kHz) do not elicit female phonotaxis or vocalization. The behavioral study was complemented by electrophysiological recordings from the auditory midbrain and by laser Doppler vibrometer measurements of the tympanic membrane's response to acoustic stimuli. These measurements revealed that females have an upper frequency limit up to 16 kHz (threshold 107 dB SPL) and no ultrasound sensitivity, unlike males which have an upper frequency limit of up to 35 kHz (87 dB SPL). Single units in the female auditory midbrain have the best excitatory frequencies (BEFs) peaked around 5 kHz, corresponding to the fundamental frequency (F0) of male's most calls, whereas the male auditory midbrain units have BEFs mostly above 8 kHz, largely consistent with the F0 of female courtship calls. Females have a frequency sensitive bandwidth (10 dB above threshold) ranged from 2 to 6 kHz, narrower than that males have (5-20 kHz). The velocity amplitude of the tympanic membranes peaked around 5 kHz in females, whereas 7 kHz in males. The results suggest that the frog species O. tormota is an example of a vertebrate, which demonstrates well phonotaxis and extraordinary sex differences in hearing

    Angular Reconstruction of a Lead Scintillating-Fiber Sandwiched Electromagnetic Calorimeter

    Full text link
    A new method called Neighbor Cell Deposited Energy Ratio (NCDER) is proposed to reconstruct incidence position in a single layer for a 3-dimensional imaging electromagnetic calorimeter (ECAL).This method was applied to reconstruct the ECAL test beam data for the Alpha Magnetic Spectrometer-02 (AMS-02). The results show that this method can achieve an angular resolution of 7.36\pm 0.08 / \sqrt(E) \oplus 0.28 \pm 0.02 degree in the determination of the photons direction, which is much more precise than that obtained with the commonly-adopted Center of Gravity(COG) method (8.4 \pm 0.1 /sqrt(E) \oplus 0.8\pm0.3 degree). Furthermore, since it uses only the properties of electromagnetic showers, this new method could also be used for other type of fine grain sampling calorimeters.Comment: 6 pages, 8 figure

    Bis(2-methyl­imidazolium) chloranilate

    Get PDF
    The asymmetric unit of the title structure, 2C4H7N2 +·C6Cl2O4 2−, consists of one 2-methyl­imidazolium cation and one-half of a chloranilate anion, the formula unit being generated by crystallographic inversion symmetry. N—H⋯O hydrogen bonds link the ions into a two-dimensional framework parallel to the (102) plane. No π–π stacking or C—H⋯π inter­actions are observed in the crystal structure

    4-Amino-2-methyl­quinoline monohydrate

    Get PDF
    The crystal structure of the title compound, C10H10N2·H2O, is stabilized by inter­molecular O—H⋯N, N—H⋯O and N—H⋯N hydrogen bonds

    Practice on the Watershed Hydrological Experimental System Reconciling Deterministic and Stochastic Subjects Based on the System Complexity: 1. Theoretical Study

    Get PDF
    This is the first of a two-part series on the watershed hydrological experimental system (WHES). Since the foundational stage and developmental stage of hydrological basin study with a duration of more than ca. one century, facing with the changing environment and, the declined risk of field study while the catchment hydrology is trapped in a theoretical impasse, a third phase of renovation on hydrological experiments seems ready to come out inevitably. Learned from Chinese decades’ experiences on the field basin study for the question of what is wrong with the status quo, our exploratory idea is reported in this part. From the viewpoint of general system theory based on the paralleled concepts of the ancient Chinese and the Western, it is considered that the adequate method should face the characters of the complex dynamic system instead of previous static, linear system. From the viewpoint of another philosophical paralleled concept of the Middle Way, it should also face the operation and organizing of the mesoscopic systems for the organized complexity. Then, a framework of WHES is suggested with its organization based on the strategy of constrain complexity and add complexity and on the strategy of manipulation including the artificial-natural and controlled-natural objects. Such a trial framework, the Chuzhou WHES, is reported including the suggested critical zone experimental block (CZEB) instead of the experimental basin (EB) in the last decades

    Practices on the Watershed Hydrological Experimental System Reconciling Deterministic and Stochastic Subjects Based on the System Complexity: 2. Practice and Test

    Get PDF
    This is the second of a two-part series on the watershed hydrological experimental system (WHES) aimed at practice and test of it at Chuzhou Hydrology Laboratory. It constitutes both natural and artificial entities of different scales, within which two typical main subjects are reviewed here. First is a natural watershed Nandadish, which is subjected to be a Critical Zone Experimental Block, under manipulation strategy of constrain complexity to compare with the pure natural watersheds, it is the controlled-natural as we termed. Second is an artificial catchment Hydrohill, under the strategy of add complexity to compare with the simple artificial lysimeters, it is the artificial-natural as we termed. The constructions and instrumentations of these experimental catchments are reviewed, especially their renovation version during recent years after a long abandonment. Some results get during the operation of Chuzhou WHES are outlined here as well

    Earthquake Forecast via Neutrino Tomography

    Full text link
    We discuss the possibility of forecasting earthquakes by means of (anti)neutrino tomography. Antineutrinos emitted from reactors are used as a probe. As the antineutrinos traverse through a region prone to earthquakes, observable variations in the matter effect on the antineutrino oscillation would provide a tomography of the vicinity of the region. In this preliminary work, we adopt a simplified model for the geometrical profile and matter density in a fault zone. We calculate the survival probability of electron antineutrinos for cases without and with an anomalous accumulation of electrons which can be considered as a clear signal of the coming earthquake, at the geological region with a fault zone, and find that the variation may reach as much as 3% for νˉe\bar \nu_e emitted from a reactor. The case for a νe\nu_e beam from a neutrino factory is also investigated, and it is noted that, because of the typically high energy associated with such neutrinos, the oscillation length is too large and the resultant variation is not practically observable. Our conclusion is that with the present reactor facilities and detection techniques, it is still a difficult task to make an earthquake forecast using such a scheme, though it seems to be possible from a theoretical point of view while ignoring some uncertainties. However, with the development of the geology, especially the knowledge about the fault zone, and with the improvement of the detection techniques, etc., there is hope that a medium-term earthquake forecast would be feasible.Comment: 6 pages, 4 figures, 1 tabl
    corecore