262 research outputs found

    Projected Spatiotemporal Dynamics of Drought under Global Warming in Central Asia

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    Drought, one of the most common natural disasters that have the greatest impact on human social life, has been extremely challenging to accurately assess and predict. With global warming, it has become more important to make accurate drought predictions and assessments. In this study, based on climate model data provided by the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), we used the Palmer Drought Severity Index (PDSI) to analyze and project drought characteristics and their trends under two global warming scenarios—1.5 °C and 2.0 °C—in Central Asia. The results showed a marked decline in the PDSI in Central Asia under the influence of global warming, indicating that the drought situation in Central Asia would further worsen under both warming scenarios. Under the 1.5 °C warming scenario, the PDSI in Central Asia decreased first and then increased, and the change time was around 2080, while the PDSI values showed a continuous decline after 2025 in the 2.0 °C warming scenario. Under the two warming scenarios, the spatial characteristics of dry and wet areas in Central Asia are projected to change significantly in the future. In the 1.5 °C warming scenario, the frequency of drought and the proportion of arid areas in Central Asia were significantly higher than those under the 2.0 °C warming scenario. Using the Thornthwaite (TH) formula to calculate the PDSI produced an overestimation of drought, and the Penman–Monteith (PM) formula is therefore recommended to calculate the index

    System Guarantee for Social Equity in Today’s China

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    Social equity is balanced and equal distribution of rights and interests. A sound system is the fundamental guarantee for social equity. Unfortunately, imperfection of the current system in China obstructed social equity in today’s China such as income distribution system, dual urbanrural system, market economic system, citizen rights and interests, protection system and social security system. To eliminate these barriers, strengthen system building and guarantee social equity, equity and justice should be taken as the primary goal of value for system building; a guarantee mechanism for social equity system should be built focusing on fairness in rights, opportunities, rules and distribution; and a system to guarantee social equity should be built and perfected with multi-tiered systems including macro basic system, medium operation system and microcosmic concrete system.Key words: Social equity; System; Guarante

    Digital Railway System

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    Ex Vivo Porcine Arterial and Chorioallantoic Membrane Acoustic Angiography Using Dual-Frequency Intravascular Ultrasound Probes

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    The presence of blood vessels within a developing atherosclerotic plaque has been shown to be correlated to increased plaque vulnerability and ensuing cardiac events, however, detecting coronary intraplaque neovascularizations poses a significant challenge in the clinic. In this paper, we demonstrate in vivo a new intravascular ultrasound imaging method using a dual-frequency transducer to visualize contrast flow in microvessels with high specificity. This method uses a specialized transducer capable of exciting contrast agents at a low frequency (5.5 MHz) while detecting their nonlinear superhamonics at a much higher frequency (37 MHz). In vitro evaluation of the approach was performed in a microvascular phantom to produce 3D renderings of simulated vessel patterns and to determine image quality metrics as a function of depth. Furthermore, the ability of the system to detect microvessels is demonstrated both ex vivo using porcine arteries and in vivo using the chorioallantoic membrane of a developing chicken embryo with optical confirmation. Dual-frequency contrast specific imaging was able to resolve vessels of a similar size to those found in vulnerable atherosclerotic plaques at clinically relevant depths. The results of this study adds growing support for further evaluation and translation of contrast specific imaging in intravascular ultrasound for the detection of vulnerable plaques in atherosclerosis

    MUD-PQFed: Towards Malicious User Detection in Privacy-Preserving Quantized Federated Learning

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    Federated Learning (FL), a distributed machine learning paradigm, has been adapted to mitigate privacy concerns for customers. Despite their appeal, there are various inference attacks that can exploit shared-plaintext model updates to embed traces of customer private information, leading to serious privacy concerns. To alleviate this privacy issue, cryptographic techniques such as Secure Multi-Party Computation and Homomorphic Encryption have been used for privacy-preserving FL. However, such security issues in privacy-preserving FL are poorly elucidated and underexplored. This work is the first attempt to elucidate the triviality of performing model corruption attacks on privacy-preserving FL based on lightweight secret sharing. We consider scenarios in which model updates are quantized to reduce communication overhead in this case, where an adversary can simply provide local parameters outside the legal range to corrupt the model. We then propose the MUD-PQFed protocol, which can precisely detect malicious clients performing attacks and enforce fair penalties. By removing the contributions of detected malicious clients, the global model utility is preserved to be comparable to the baseline global model without the attack. Extensive experiments validate effectiveness in maintaining baseline accuracy and detecting malicious clients in a fine-grained mannerComment: 13 pages,13 figure

    Comparative simulation analysis based on edemrecurdyn coupling

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    In order to verify the effectiveness of the three-stage potato soil separation device, a comparative simulation should be carried out using the EDEM-Recurdyn simulation method. The results showed that the design of the three-stage potato soil separation unit could reduce damage to potato tubers

    A preliminary engineering design of intravascular dual-frequency transducers for contrast-enhanced acoustic angiography and molecular imaging

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    Current intravascular ultrasound (IVUS) probes are not optimized for contrast detection because of their design for high-frequency fundamental-mode imaging. However, data from transcutaneous contrast imaging suggests the possibility of utilizing contrast ultrasound for molecular imaging or vasa vasorum assessment to further elucidate atherosclerotic plaque deposition. This paper presents the design, fabrication, and characterization of a small-aperture (0.6 × 3 mm) IVUS probe optimized for high-frequency contrast imaging. The design utilizes a dual-frequency (6.5 MHz/30 MHz) transducer arrangement for exciting microbubbles at low frequencies (near their resonance) and detecting their broadband harmonics at high frequencies, minimizing detected tissue backscatter. The prototype probe is able to generate nonlinear microbubble response with more than 1.2 MPa of rarefractional pressure (mechanical index: 0.48) at 6.5 MHz, and is also able to detect microbubble response with a broadband receiving element (center frequency: 30 MHz, −6-dB fractional bandwidth: 58.6%). Nonlinear super-harmonics from microbubbles flowing through a 200-μm-diameter micro-tube were clearly detected with a signal-to-noise ratio higher than 12 dB. Preliminary phantom imaging at the fundamental frequency (30 MHz) and dual-frequency super-harmonic imaging results suggest the promise of small aperture, dual-frequency IVUS transducers for contrast-enhanced IVUS imaging

    Development status of potato harvester in China

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    A late start has slowed the development of potato harvesters in China. Although research and development by companies such as MENOW and Hongzhu have raised the level of equipment in this field, problems remain
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