686 research outputs found

    On the 2-part of the Birch-Swinnerton-Dyer conjecture for elliptic curves with complex multiplication

    Full text link
    Given an elliptic curve E over Q with complex multiplication having good reduction at 2, we investigate the 2-adic valuation of the algebraic part of the L-value at 1 for a family of quadratic twists. In particular, we prove a lower bound for this valuation in terms of the Tamagawa number in a form predicted by the conjecture of Birch and Swinnerton-Dyer

    Elastic modulus of viral nanotubes

    Get PDF
    We report an experimental and theoretical study of the radial elasticity of tobacco mosaic virus (TMV) nanotubes. An atomic force microscope tip is used to apply small radial indentations to deform TMV nanotubes. The initial elastic response of TMV nanotubes can be described by finite-element analysis in 5 nm indentation depths and Hertz theory in 1.5 nm indentation depths. The derived radial Young\u27s modulus of TMV nanotubes is 0.92 +/- 0.15 GPa from finite-element analysis and 1.0 +/- 0.2 GPa from the Hertz model, which are comparable with the reported axial Young\u27s modulus of 1.1 GPa [Falvo et al., Biophys. J. 72, 1396 (1997)]

    Effect of Particle Size Distribution on Fluid Rheology of High Density Drilling Fluid

    Get PDF
    The control and maintenance of rheological properties is the key technical problem that needs to be solved for high density drilling fluid. The influence of particle size distribution on the rheology of high density drilling fluid is analyzed. In order to identify the best particle size distribution of barite and iron ore, the influence of distribution modulus on the rheology of high density drilling fluid weighted by barite and iron ore is investigated based on the Aflred distribution equation. The experimental results show that weighting materials particle distribution has great effect on rheological properties of high density drilling fluid. When the barite particle distribution modulus n=0.4 and iron ore powder particle distribution modulus n=0.6, the rheology of high density drilling fluid is best, while the low settlement density difference and low HTHP filtrate loss is maintained

    CCD photometric study of the W UMa-type binary II CMa in the field of Berkeley 33

    Full text link
    The CCD photometric data of the EW-type binary, II CMa, which is a contact star in the field of the middle-aged open cluster Berkeley 33, are presented. The complete R light curve was obtained. In the present paper, using the five CCD epochs of light minimum (three of them are calculated from Mazur et al. (1993)'s data and two from our new data), the orbital period P was revised to 0.22919704 days. The complete R light curve was analyzed by using the 2003 version of W-D (Wilson-Devinney) program. It is found that this is a contact system with a mass ratio q=0.9q=0.9 and a contact factor f=4.1f=4.1%. The high mass ratio (q=0.9q=0.9) and the low contact factor (f=4.1f=4.1%) indicate that the system just evolved into the marginal contact stage

    Clamping Force Distribution within Press Pack IGBTs

    Get PDF
    Press pack insulated gated bipolar transistors (PP IGBTs) have been gradually used in the high-voltage and high-power-density applications, such as the power system and electric locomotive, with its advantages of double-sided cooling, higher power density, and easy to connect in series compared with traditional wire-bonded power IGBT modules. However, the clamping force is quite important for PP IGBTs because too much clamping fore will cause mechanical damage to the silicon chips and too little clamping force will increase the junction temperature of the silicon chips due to the increased thermal contact resistance. And eventually it leads to thermal damage. Furthermore, the clamping force distribution within PP IGBTs is affected by many factors, and they can be divided into the internal and external factors. The finite element analysis model of the PP IGBTs is established based on the theory of elastic mechanics to obtain the influence of the affect factors, including the external clamping modes, spring design, thermal stress, the machining accuracy, and so on. The contribution of those affect factors to the clamping force distribution is ranked, and this can be a guideline not only for users but also for the manufacturers

    EFFECTS OF MONITORING SIGNAL HYSTERESIS ON SPEED REGULATION FOR THE AERO-DERIVATIVE GAS TURBINE

    Get PDF
    Sensor aging and sensor failure are the common phenomena due to the high temperature and pressure environment for gas turbines, which can lead to hysteresis of monitoring signals. In this paper, a kind of aero-derivative gas turbine is taken as the research object. The hysteresis effects of single monitoring signal and coupling of multiple monitoring signals on speed control are mainly studied, and the analysis is carried out from the perspective of adjustment time, overshoot, fuel quantity and fuel quantity regulation output. The analysis results show that the pressure signal hysteresis will lead to speed suspension. The speed signal hysteresis will change the speed regulation into a multi-step mode. When the monitoring signal hysteresis is coupled, the effect of pressure signal hysteresis is greater than that of speed signal hysteresis. The results of this paper can provide a reference for the optimal design of speed control of aero-derivative gas turbine

    Industrial Anomaly Detection with Domain Shift: A Real-world Dataset and Masked Multi-scale Reconstruction

    Full text link
    Industrial anomaly detection (IAD) is crucial for automating industrial quality inspection. The diversity of the datasets is the foundation for developing comprehensive IAD algorithms. Existing IAD datasets focus on the diversity of data categories, overlooking the diversity of domains within the same data category. In this paper, to bridge this gap, we propose the Aero-engine Blade Anomaly Detection (AeBAD) dataset, consisting of two sub-datasets: the single-blade dataset and the video anomaly detection dataset of blades. Compared to existing datasets, AeBAD has the following two characteristics: 1.) The target samples are not aligned and at different scales. 2.) There is a domain shift between the distribution of normal samples in the test set and the training set, where the domain shifts are mainly caused by the changes in illumination and view. Based on this dataset, we observe that current state-of-the-art (SOTA) IAD methods exhibit limitations when the domain of normal samples in the test set undergoes a shift. To address this issue, we propose a novel method called masked multi-scale reconstruction (MMR), which enhances the model's capacity to deduce causality among patches in normal samples by a masked reconstruction task. MMR achieves superior performance compared to SOTA methods on the AeBAD dataset. Furthermore, MMR achieves competitive performance with SOTA methods to detect the anomalies of different types on the MVTec AD dataset. Code and dataset are available at https://github.com/zhangzilongc/MMR.Comment: submit to Computers in Industr

    Subliminal perception of others’ physical pain induces personal distress rather than empathic concern

    Get PDF
    Acknowledgements We thank the members of the research group for their revising this paper. Funding This research was supported by Humanities and Social Science Research Youth Fund Project of the Ministry of Education (19YJC190021) Grants to Juan Song. The funding body has no further role in the design of the study, data collection, analysis, data interpretation, and writing of the manuscript.Peer reviewedPublisher PD
    corecore