71 research outputs found
Michael-Simon Sobolev inequalities in Euclidean space
Inspired by [1, 13], we prove Michael-Simon type inequalities for smooth
symmetric uniformly positive define (0, 2)-tensor fields on compact
submanifolds in Euclidean space by the Alexandrov-Bakelman-Pucci (ABP) method.Comment: 10 page
Topology-aware Graph Neural Networks for Learning Feasible and Adaptive ac-OPF Solutions
Solving the optimal power flow (OPF) problem is a fundamental task to ensure
the system efficiency and reliability in real-time electricity grid operations.
We develop a new topology-informed graph neural network (GNN) approach for
predicting the optimal solutions of real-time ac-OPF problem. To incorporate
grid topology to the NN model, the proposed GNN-for-OPF framework innovatively
exploits the locality property of locational marginal prices and voltage
magnitude. Furthermore, we develop a physics-aware (ac-)flow feasibility
regularization approach for general OPF learning. The advantages of our
proposed designs include reduced model complexity, improved generalizability
and feasibility guarantees. By providing the analytical understanding on the
graph subspace stability under grid topology contingency, we show the proposed
GNN can quickly adapt to varying grid topology by an efficient re-training
strategy. Numerical tests on various test systems of different sizes have
validated the prediction accuracy, improved flow feasibility, and topology
adaptivity capability of our proposed GNN-based learning framework
Exogenous testosterone decreases men’s sensitivity to vocal cues of male dominance
Assessing dominance is important for effective social interactions, and prior research suggests that testosterone is associated with men's dominance perceptions. The present study tested for a causal effect of exogenous testosterone on men's sensitivity to vocal cues of other men's dominance, an important parameter in male-male competition across species. One hundred and thirty-nine Chinese men received a single dose (150 mg) of testosterone or placebo gel in a double-blind, placebo-controlled, between-participant design. Participants reported their own dominance and judged other men's dominance from voices. Men's dominance sensitivity was significantly weaker in the testosterone group compared to those in the placebo group. Moreover, men's dominance sensitivity was negatively associated with their self-reported dominance in our Chinese sample, consistent with findings from Western populations. These results indicate that exogenous testosterone has a causal effect in decreasing men's dominance sensitivity, consistent with the Challenge Hypothesis, suggesting that the fluctuation of testosterone concentration mediates individuals' behaviors. Additionally, the present study could motivate further work on vocal assessment in the context of competition in humans and other species
Atomic Ramsey interferometry with S- and D-band in a triangular optical lattice
Ramsey interferometers have wide applications in science and engineering.
Compared with the traditional interferometer based on internal states, the
interferometer with external quantum states has advantages in some applications
for quantum simulation and precision measurement. Here, we develop a Ramsey
interferometry with Bloch states in S- and D-band of a triangular optical
lattice for the first time. The key to realizing this interferometer in
two-dimensionally coupled lattice is that we use the shortcut method to
construct pulse. We observe clear Ramsey fringes and analyze the
decoherence mechanism of fringes. Further, we design an echo pulse
between S- and D-band, which significantly improves the coherence time. This
Ramsey interferometer in the dimensionally coupled lattice has potential
applications in the quantum simulations of topological physics, frustrated
effects, and motional qubits manipulation
Computationally Efficient Approximations Using Adaptive Weighting Coefficients for Solving Structural Optimization Problems
With rapid development of advanced manufacturing technologies and high demands for innovative lightweight constructions to mitigate the environmental and economic impacts, design optimization has attracted increasing attention in many engineering subjects, such as civil, structural, aerospace, automotive, and energy engineering. For nonconvex nonlinear constrained optimization problems with continuous variables, evaluations of the fitness and constraint functions by means of finite element simulations can be extremely expensive. To address this problem by algorithms with sufficient accuracy as well as less computational cost, an extended multipoint approximation method (EMAM) and an adaptive weighting-coefficient strategy are proposed to efficiently seek the optimum by the integration of metamodels with sequential quadratic programming (SQP). The developed EMAM stems from the principle of the polynomial approximation and assimilates the advantages of Taylor’s expansion for improving the suboptimal continuous solution. Results demonstrate the superiority of the proposed EMAM over other evolutionary algorithms (e.g., particle swarm optimization technique, firefly algorithm, genetic algorithm, metaheuristic methods, and other metamodeling techniques) in terms of the computational efficiency and accuracy by four well-established engineering problems. The developed EMAM reduces the number of simulations during the design phase and provides wealth of information for designers to effectively tailor the parameters for optimal solutions with computational efficiency in the simulation-based engineering optimization problems
An Efficient Spatial-Temporal Trajectory Planner for Autonomous Vehicles in Unstructured Environments
As a core part of autonomous driving systems, motion planning has received
extensive attention from academia and industry. However, real-time trajectory
planning capable of spatial-temporal joint optimization is challenged by
nonholonomic dynamics, particularly in the presence of unstructured
environments and dynamic obstacles. To bridge the gap, we propose a real-time
trajectory optimization method that can generate a high-quality whole-body
trajectory under arbitrary environmental constraints. By leveraging the
differential flatness property of car-like robots, we simplify the trajectory
representation and analytically formulate the planning problem while
maintaining the feasibility of the nonholonomic dynamics. Moreover, we achieve
efficient obstacle avoidance with a safe driving corridor for unmodelled
obstacles and signed distance approximations for dynamic moving objects. We
present comprehensive benchmarks with State-of-the-Art methods, demonstrating
the significance of the proposed method in terms of efficiency and trajectory
quality. Real-world experiments verify the practicality of our algorithm. We
will release our codes for the research communit
Mini percutaneous nephrolithotomy is a noninferior modality to standard percutaneous nephrolithotomy for the management of 20-40 mm renal calculi: A Multicenter randomized controlled trial
Background: High quality of evidence comparing mini percutaneous nephrolithotomy (mPNL) with standard percutaneous nephrolithotomy (sPNL) for the treatment of larger-sized renal stones is lacking. Objective: To compare the efficacy and safety of mPNL and sPNL for the treatment of 20–40 mm renal stones. Design, setting, and participants: A parallel, open-label, and noninferior randomized controlled trial was performed at 20 Chinese centers (2016–2019). The inclusion criteria were patients 18–70 yr old, with normal renal function, and 20–40 mm renal stones. Intervention: Percutaneous nephrolithotomy PNL was performed using either 18 F or 24 F percutaneous nephrostomy tracts. Outcome measurements and statistical analysis: The primary outcome was the one-session stone-free rate (SFR). The secondary outcomes included operating time, visual analog pain scale (VAS) score, blood loss, complications as per the Clavien-Dindo grading system, and length of hospitalization. Results and limitations: The 1980 intention-to-treat patients were randomized. The mPNL group achieved a noninferior one-session SFR to the sPNL group by the one-side noninferiority test (0.5% [difference], p < 0.001). The transfusion and embolization rates were comparable; however, the sPNL group had a higher hemoglobin drop (5.2 g/l, p < 0.001). The sPNL yielded shorter operating time (–2.2 min, p = 0.008) but a higher VAS score (0.8, p < 0.001). Patients in the sPNL group also had longer hospitalization (0.6 d, p < 0.001). There was no statistically significant difference in fever or urosepsis occurrences. The study's main limitation was that only 18F or 24F tract sizes were used. Conclusions: Mini mPNL achieves noninferior SFR outcomes to sPNL, but with reduced bleeding, less postoperative pain, and shorter hospitalization. Patient summary: We evaluated the surgical outcomes of percutaneous nephrolithotomy using two different sizes of nephrostomy tracts in a large population. We found that the smaller tract might be a sensible alternative for patients with 20–40 mm renal stones. This multicenter, parallel, open-label, and noninferior randomized controlled trial showed that mini percutaneous nephrolithotomy achieved noninferior stone-free rate with advantages of reduced blood loss, less postoperative pain, and shorter hospitalization. Mini percutaneous nephrolithotomy should be considered a sensible alternative treatment of 20–40 mm renal stones.grants from high-level development funding of Guangzhou Medical Universit
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Into the multiverse of structural similarity
Since its initial appearance more than twenty years ago, Structural Similarity (SSIM) has been widely adopted by film and television industries for evaluating perceived quality of images and videos. The introduction of structural information not only marked the beginning of estimating perceptual degradation, but inspired numerous variants and following models as well. With the rapid growth of Internet coverage and connection speed, streaming services and online platforms have become commonplace in people’s daily lives. In an effort to control customers’ Quality of Experience, industries have adopted various standards for Image/Video Quality Assessment (IQA/VQA), including but not limited to SSIM. A variety of applications and softwares have been developed, ranging from open source libraries to commercial products. Needless to say, these implementations are different from each other in terms of functionality and performance. We conducted a brief survey on a couple of widely adopted implementations, as well as investigated various steps in the pipeline of computation. Based on the results, we propose a list of observations and recommendations as a reference for designersElectrical and Computer Engineerin
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