515 research outputs found
Entanglement dynamics of a two-qubit system coupled individually to Ohmic baths
Developed originally for the Holstein polaron, the Davydov D1 ansatz is an
efficient, yet extremely accurate trial state for time-dependent variation of
the spin-boson model [J. Chem. Phys. 138, 084111 (2013)]. In this work, the
Dirac-Frenkel time-dependent variational procedure utilizing the Davydov D1
ansatz is implemented to study entanglement dynamics of two qubits under the
influence of two independent baths. The Ohmic spectral density is used without
the Born-Markov approximation or the rotating-wave approximation. In the strong
coupling regime finite-time disentanglement is always found to exist, while at
the intermediate coupling regime, the entanglement dynamics calculated by
Davydov D1 ansatz displays oscillatory behavior in addition to entanglement
disappearance and revival.Comment: 8 pages, 3 figure
A Phantom Study on Target Localization Accuracy Using Cone-Beam Computed Tomography
The purpose of this study is to evaluate the 3-dimensional target localization accuracy of cone-beam computed tomography (CBCT) using an on-board imager (OBI). An anthropomorphic pelvis phantom was used to simulate a range of offsets in the three translational directions and rotations around each of the three axes. After a translational or rotational offset was applied, a CBCT scan of the phantom was followed by image registration to detect the offsets in six degrees. The detected offsets were compared to the offset actually applied to give the detection error of the phantom position. Afterwards, the phantom was positioned by automatically moving the couch based on the detected offsets. A second CBCT scan followed by image registration was performed to give the residual error of the phantom positioning. On the average the detection errors and their standard deviations along the lateral, longitudinal and vertical axis are 0.3 ± 0.1, 0.3 ± 0.1 and 0.4 ± 0.1 mm respectively with respect to translational shifts ranging from 0 to 10 mm. The corresponding residual errors after positioning are 0.3 ± 0.1, 0.5 ± 0.1 and 0.3 ± 0.1 mm. For simulated rotational shifts ranging from 0 to 5 degrees, the average detection error and their standard deviation around lateral, longitudinal, and vertical axes are 0.1 ± 0.0, 0.2 ± 0.0, and 0.2 ± 0.0 degrees respectively. The residual errors after positioning are 0.4 ± 0.1, 0.6 ± 0.1, and 0.3 ± 0.1 mm along the lateral, longitudinal and vertical directions. These results indicate that target localization based on CBCT is capable of achieving sub-millimeter accuracy
Deep Eutectic Solvent-Based Microwave-Assisted Extraction of Baicalin from Scutellaria baicalensis
Deep eutectic solvents (DESs) have attracted significant attention as green media for the extraction and separation of natural compounds from Chinese medicine. In this study, a hydrophobic DESs-based microwave-assisted extraction (MAE) was successfully used to efficiently extract baicalin from Scutellaria baicalensis Georgi. Firstly, DecA: N4444-Cl (DES-1 , molar ratio 1 : 2) was screened and selected as the most appropriate DES by comparing the extraction yield in different hydrophobic DESs. Based on the extraction yield of baicalin, response surface methodology (RSM) was employed to model and optimize the parameters (extraction temperature, liquid-solid ratio, and extraction time). Furthermore, the maximum yield of 106.96 mg·g−1 was achieved under optimum conditions in DES-containing aqueous solutions (33 vol% water content), which reached a similar level that was conducted using the pharmacopoeia procedure (104.94 mg·g−1). These results indicated that the proposed method is an excellent alternative for the extraction of baicalin
Gear Fault Detection Based on Teager-Huang Transform
Gear fault detection based on Empirical Mode Decomposition (EMD) and Teager Kaiser Energy Operator (TKEO) technique is presented. This novel method is named as Teager-Huang transform (THT). EMD can adaptively decompose the vibration signal into a series of zero mean Intrinsic Mode Functions (IMFs). TKEO can track the instantaneous amplitude and instantaneous frequency of the Intrinsic Mode Functions at any instant. The experimental results provide effective evidence that Teager-Huang transform has better resolution than that of Hilbert-Huang transform. The Teager-Huang transform can effectively diagnose the fault of the gear, thus providing a viable processing tool for gearbox defect detection and diagnosis
Energy management strategy based on dynamic programming for dual source trolleybus
Dizajniran je novi model trolejbusa s dvojnim izvorom napajanja s akumulatorom i super električnim kondenzatorom, a s tim povezani parametri dinamičkog sustava dizajnirani su na temelju teorije dedukcije. Simulacijski model razvijen je u ADVISOR softveru. Zasnovana na analizi radnih modova trolejbusa s dvojnim sustavom napajanja, dizajnirana je optimalna strategija upravljanja na temelju dinamičkog programiranja čiji je cilj reduciranje vršne snage mreže on-line moda i potrošnje energije off-line moda. Uz to, upravljačka strategija zasnovana na tom pravilu također je implementirana i uspoređena s poboljšanom strategijom upravljanja. Rezultati su pokazali da metode optimizacije temeljene na dinamičkom programiranju mogu u potpunosti iskoristiti super električni kondenzator velike snage, s brzim punjenjem i pražnjenjem, i učinkovitije rasporediti energiju među izvorima energije te poboljšati dinamičke i ekonomske karakteristike trolejbusa.The dual source trolleybus of a new model with battery and super capacitor energy storage system was designed. The related parameters of dynamical system were designed on the basis of theory deduction, and the simulation model was re-developed in ADVISOR software. Based on the analysis of work modes of the dual source trolleybus, an optimal control strategy based on Dynamic Programming was designed, which is aimed at reducing grid peaking power of on-line mode and energy consumption of off-line mode. In addition, the rule based control strategy has also been implemented and compared to the optimized control strategy. The results have demonstrated that the optimization techniques based on Dynamic Programming can make full use of the supercapacitors with high power and fast charging/discharging characteristics, and more effectively distribute the power between the power sources, improve the dynamic performance and economic performance of the trolleybus
COMET: NFT Price Prediction with Wallet Profiling
As the non-fungible token (NFT) market flourishes, price prediction emerges
as a pivotal direction for investors gaining valuable insight to maximize
returns. However, existing works suffer from a lack of practical definitions
and standardized evaluations, limiting their practical application. Moreover,
the influence of users' multi-behaviour transactions that are publicly
accessible on NFT price is still not explored and exhibits challenges. In this
paper, we address these gaps by presenting a practical and hierarchical problem
definition. This approach unifies both collection-level and token-level task
and evaluation methods, which cater to varied practical requirements of
investors. To further understand the impact of user behaviours on the variation
of NFT price, we propose a general wallet profiling framework and develop a
COmmunity enhanced Multi-bEhavior Transaction graph model, named COMET. COMET
profiles wallets with a comprehensive view and considers the impact of diverse
relations and interactions within the NFT ecosystem on NFT price variations,
thereby improving prediction performance. Extensive experiments conducted in
our deployed system demonstrate the superiority of COMET, underscoring its
potential in the insight toolkit for NFT investors.Comment: Accepted by KDD 2024 (ADS Track
Hallo: Hierarchical Audio-Driven Visual Synthesis for Portrait Image Animation
The field of portrait image animation, driven by speech audio input, has
experienced significant advancements in the generation of realistic and dynamic
portraits. This research delves into the complexities of synchronizing facial
movements and creating visually appealing, temporally consistent animations
within the framework of diffusion-based methodologies. Moving away from
traditional paradigms that rely on parametric models for intermediate facial
representations, our innovative approach embraces the end-to-end diffusion
paradigm and introduces a hierarchical audio-driven visual synthesis module to
enhance the precision of alignment between audio inputs and visual outputs,
encompassing lip, expression, and pose motion. Our proposed network
architecture seamlessly integrates diffusion-based generative models, a
UNet-based denoiser, temporal alignment techniques, and a reference network.
The proposed hierarchical audio-driven visual synthesis offers adaptive control
over expression and pose diversity, enabling more effective personalization
tailored to different identities. Through a comprehensive evaluation that
incorporates both qualitative and quantitative analyses, our approach
demonstrates obvious enhancements in image and video quality, lip
synchronization precision, and motion diversity. Further visualization and
access to the source code can be found at:
https://fudan-generative-vision.github.io/hallo.Comment: 20 page
Incidence and risk factors for amputation in Chinese patients with diabetic foot ulcers: a systematic review and meta-analysis
ObjectiveThis study aimed to comprehensively analyze the incidence of amputation in Chinese patients with diabetic foot ulcers (DFUs).MethodsThe Preferred Reporting Items for a Systematic Review and Meta-analysis (PRISMA) guidelines were used. The CNKI, Wanfang Data, VIP, PubMed, Web of Science, and Embase databases were searched to collect relevant literature on the incidence of amputation in Chinese patients with DFUs. Two researchers independently screened the literature, extracted data, and evaluated the risk of bias. The data were systematically analyzed using Stata 17.0 software to determine the incidence of amputation in this patient population.ResultsA total of 25 papers were included in the study, revealing an incidence of amputation in Chinese patients with DFUs of 22.4% (95% confidence interval: 18.3–26.5%). The subgroup analysis revealed that a history of ulcers, Wagner grade >3, and diabetic peripheral vascular disease were the primary risk factors associated with a higher incidence of amputation in Chinese patients with DFUs (P<0.05). Among Chinese patients with DFUs, the amputation group and the non-amputation group showed significant differences in body mass index, duration of DFUs, total cholesterol, triglyceride, fasting blood glucose, white blood cell count, hemoglobin A1c, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, high-sensitivity C-reactive protein, and uric acid (P<0.05).ConclusionThe high incidence of amputation among Chinese patients with DFUs indicates that interventions should be implemented to prevent or minimize amputations.Systematic review registrationhttps://www.crd.york.ac.uk/prospero, identifier CRD42023463976
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