Publications (35)
Stirring Speeds Up Chemical Reaction
Siming He, Alexander Kiselev
We consider absorbing chemical reactions in a fluid flow modeled by the coupled advection-reaction-diffusion equations. In these systems, the interplay between chemical diffusion a…
Distance comparison principle and Grayson type theorem in the three dimensional curve shortening flow
Siming He
In this paper, we use the distance comparison principle, first been developed by G. Huisken, to study the spatial curve shortening flow. We have got the result that if the initial…
Localized Enhanced Dissipation: A Hypocoercivity Approach
Siming He
In this paper, we consider the passive scalar solutions in shear flows with critical points. With a detailed hypocoercivity functional, we develop streamline-wise enhanced dissipat…
Stability threshold of nearly-Couette shear flows with Navier boundary conditions in 2D
Jacob Bedrossian, Siming He, Sameer Iyer +1
In this work, we prove a threshold theorem for the 2D Navier-Stokes equations posed on the periodic channel, , supplemented with Navier boundary condition…
Mixing, Enhanced Dissipation and Phase Transition in the Kinetic Vicsek Model
Mengyang Gu, Siming He
In this paper, we study the kinetic Vicsek model, which serves as a starting point for describing the polarization phenomena observed in the experiments of fibroblasts moving on li…
FARM: Find Anything using Relational Spatial Memory
Siming He, Leo Huang, Adam Lilja +7
Robots operating in homes, warehouses, and other object-rich environments need memory systems that can find specific object instances on demand. Object-level memory alone is often…
A Note on Enhanced Dissipation and Taylor Dispersion of Time-dependent Shear Flows
Daniel Coble, Siming He
This paper explores the phenomena of enhanced dissipation and Taylor dispersion in solutions to the passive scalar equations subject to time-dependent shear flows. The hypocoercivi…
Small scale creation for solutions of the SQG equation
Siming He, Alexander Kiselev
We construct examples of solutions to the conservative surface quasi-geostrophic (SQG) equation that must either exhibit infinite in time growth of derivatives or blow up in finite…
Enhanced dissipation and blow-up suppression in a chemotaxis-fluid system
Siming He
In this paper, we investigate a coupled Patlak-Keller-Segel-Navier-Stokes (PKS-NS) system. We show that globally regular solutions with arbitrary large cell populations exist. The…
Couette Flow with Robin Boundary Condition (I): the viscosity-independent friction
Siming He, Binqian Niu, Weiren Zhao
This article is the first paper in the series. In this series of articles, we will examine the influence of the friction factor at the solid--fluid boundary on the stability o…
Pseudo-Gevrey Smoothing for the Passive Scalar Equations near Couette
Jacob Bedrossian, Siming He, Sameer Iyer +1
In this article, we study the regularity theory for two linear equations that are important in fluid dynamics: the passive scalar equation for (time-varying) shear flows close to C…
Uniform Inviscid Damping and Inviscid Limit of the 2D Navier-Stokes equation with Navier Boundary Conditions
Jacob Bedrossian, Siming He, Sameer Iyer +1
We consider the 2D, incompressible Navier-Stokes equations near the Couette flow, , set on the channel , supplemented with Navier b…
Suppressing chemotactic blow-up through a fast splitting scenario on the plane
Siming He, Eitan Tadmor
We revisit the question of global regularity for the Patlak-Keller-Segel (PKS) chemotaxis model. The classical 2D hyperbolic-elliptic model blows up for initial mass M>8Ï. We cons…
An Active Perception Game for Robust Exploration
Siming He, Yuezhan Tao, Igor Spasojevic +2
Active perception approaches select future viewpoints by using some estimate of the information gain. An inaccurate estimate can be detrimental in critical situations, e.g., locati…
Suppression of blow-up in Parabolic-Parabolic Patlak-Keller-Segel via strictly monotone shear flows
Siming He
In this paper we consider the parabolic-parabolic Patlak-Keller-Segel models in with advection by a large strictly monotone shear flow. Without the she…
Global regularity of two-dimensional flocking hydrodynamics
Siming He, Eitan Tadmor
We study the systems of Euler equations which arise from agent-based dynamics driven by velocity \emph{alignment}. It is known that smooth solutions of such systems must flock, nam…
Time-dependent Flows and Their Applications in Parabolic-parabolic Patlak-Keller-Segel Systems Part I: Alternating Flows
Siming He
We consider the three-dimensional parabolic-parabolic Patlak-Keller-Segel equations (PKS) subject to ambient flows. Without the ambient fluid flow, the equation is super-critical i…
On the -critical mass threshold of a Patlak-Keller-Segel-Navier-Stokes system
Yishu Gong, Siming He
In this paper, we proposed a coupled Patlak-Keller-Segel-Navier-Stokes system, which has dissipative free energy. On the plane $\rr^2$, if the total mass of the cells is strictly l…
Digital Engagement, Income Disparities, and Job Seeking in the United States since 2010
Shaolong Wu, Yijiang River Dong, Siming He
The paper analyzes U.S. survey data to show that people who use the internet daily earn more and are more likely to be continuously employed than those who use it less or not at al…
Stability threshold of close-to-Couette shear flows with no-slip boundary conditions in 2D
Jacob Bedrossian, Siming He, Sameer Iyer +2
In this paper, we develop a stability threshold theorem for the 2D incompressible Navier-Stokes equations on the channel, supplemented with the no-slip boundary condition. The init…
Boundary layer models of the Hou-Luo scenario
Siming He, Alexander Kiselev
Finite time blow up vs global regularity question for 3D Euler equation of fluid mechanics is a major open problem. Several years ago, Luo and Hou \cite{HouLuo14} proposed a new fi…
A game of alignment:collective behavior of multi-species
Siming He, Eitan Tadmor
We study the (hydro-)dynamics of multi-species driven by alignment. What distinguishes the different species is the protocol of their interaction with the rest of the crowd: the co…
Sampling and Optimization meet Enhanced Flows
Yuan Gao, Siming He, Eitan Tadmor
It is well known that the computational realization of Gibbs probability measures, , plays a central role in sampling and optimization. In this paper…
Transition Threshold for Strictly Monotone Shear Flows in Sobolev Spaces
Rajendra Beekie, Siming He
We study the stability of spectrally stable, strictly monotone, smooth shear flows in the 2D Navier-Stokes equations on with small viscosity . We…
Active Perception using Neural Radiance Fields
Siming He, Christopher D. Hsu, Dexter Ong +2
We study active perception from first principles to argue that an autonomous agent performing active perception should maximize the mutual information that past observations posses…
Random search in fluid flow aided by chemotaxis
Yishu Gong, Siming He, Alexander Kiselev
In this paper, we consider the dynamics of a 2D target-searching agent performing Brownian motion under the influence of fluid shear flow and chemical attraction. The analysis is m…
From NeRFs to Gaussian Splats, and Back
Siming He, Zach Osman, Pratik Chaudhari
For robotics applications where there is a limited number of (typically ego-centric) views, parametric representations such as neural radiance fields (NeRFs) generalize better than…
Are we really making much progress? Revisiting, benchmarking, and refining heterogeneous graph neural networks
Qingsong Lv, Ming Ding, Qiang Liu +7
Heterogeneous graph neural networks (HGNNs) have been blossoming in recent years, but the unique data processing and evaluation setups used by each work obstruct a full understandi…
Enhanced dissipation, hypoellipticity for passive scalar equations with fractional dissipation
Siming He
We consider the passive scalar equations subject to shear flow advection and fractional dissipation. The enhanced dissipation estimates are derived. For classical passive scalar eq…
Suppression of blow-up in Patlak-Keller-Segel via shear flows
Jacob Bedrossian, Siming He
In this paper we consider the parabolic-elliptic Patlak-Keller-Segel models in with with the additional effect of advection by a large shear flow. Without the…
Multi-species Patlak-Keller-Segel system
Siming He, Eitan Tadmor
We study the regularity and large-time behavior of a crowd of species driven by chemo-tactic interactions. What distinguishes the different species is the way they interact with th…
Inviscid damping and enhanced dissipation of the boundary layer for 2D Navier-Stokes linearized around Couette flow in a channel
Jacob Bedrossian, Siming He
We study the 2D Navier-Stokes equations linearized around the Couette flow in the periodic channel with no-slip boundary conditions in the vanis…
Time-dependent Flows and Their Applications in Parabolic-parabolic Patlak-Keller-Segel Systems Part II: Shear Flows
Siming He
In this study, we investigate the behavior of three-dimensional parabolic-parabolic Patlak-Keller-Segel (PKS) systems in the presence of ambient shear flows. Our findings demonstra…
Estimating the Diameter at Breast Height of Trees in a Forest from RGB
Siming He, Zachary Osman, Fernando Cladera +5
Forest inventories rely on accurate measurements of the diameter at breast height (DBH) for ecological monitoring, resource management, and carbon accounting. While LiDAR-based tec…
On the Fast Spreading Scenario
Siming He, Eitan Tadmor, Andrej Zlatoš
We study two types of divergence-free fluid flows on unbounded domains in two and three dimensions -- hyperbolic and shear flows -- and their influence on chemotaxis and combustion…