340 research outputs found
A novel multipath-transmission supported software defined wireless network architecture
The inflexible management and operation of today\u27s wireless access networks cannot meet the increasingly growing specific requirements, such as high mobility and throughput, service differentiation, and high-level programmability. In this paper, we put forward a novel multipath-transmission supported software-defined wireless network architecture (MP-SDWN), with the aim of achieving seamless handover, throughput enhancement, and flow-level wireless transmission control as well as programmable interfaces. In particular, this research addresses the following issues: 1) for high mobility and throughput, multi-connection virtual access point is proposed to enable multiple transmission paths simultaneously over a set of access points for users and 2) wireless flow transmission rules and programmable interfaces are implemented into mac80211 subsystem to enable service differentiation and flow-level wireless transmission control. Moreover, the efficiency and flexibility of MP-SDWN are demonstrated in the performance evaluations conducted on a 802.11 based-testbed, and the experimental results show that compared to regular WiFi, our proposed MP-SDWN architecture achieves seamless handover and multifold throughput improvement, and supports flow-level wireless transmission control for different applications
3D Dynamic Motion Planning for Robot-Assisted Cannula Flexible Needle Insertion into Soft Tissue
In robot-assisted needle-based medical procedures, insertion motion planning is a crucial aspect. 3D dynamic motion planning for a cannula flexible needle is challenging with regard to the nonholonomic motion of the needle tip, the presence of anatomic obstacles or sensitive organs in the needle path, as well as uncertainties due to the dynamic environment caused by the movements and deformations of the organs. The kinematics of the cannula flexible needle is calculated in this paper. Based on a rapid and robust static motion planning algorithm, referred to as greedy heuristic and reachability-guided rapidly-exploring random trees, a 3D dynamic motion planner is developed by using replanning. Aiming at the large detour problem, the convergence problem and the accuracy problem that replanning encounters, three novel strategies are proposed and integrated into the conventional replanning algorithm. Comparisons are made between algorithms with and without the strategies to verify their validity. Simulations showed that the proposed algorithm can overcome the above-noted problems to realize real-time replanning in a 3D dynamic environment, which is appropriate for intraoperative planning. © 2016 Author
Agent-based artificial financial market with evolutionary algorithm
In traditional financial studies, existing approaches are unable to
address increasingly complex problems. In this paper, an artificial
financial market is proposed, in accordance with the adaptation
market hypothesis, using artificial intelligence algorithms. This
market includes three types of agents with different investments
and risk preferences, representing the heterogeneity of traders.
Genetic network programming is combined with a state-actionreward-state-action (SARSA)(k) algorithm for designing the market
to reflect the adaptation of technical agents. A pricing mechanism
is taken into consideration, based on the auction mechanism of
the Chinese securities market. The characteristics of price time
series are analyzed to determine whether excessive volatility
exists in four different markets. Explanations are provided for the
corresponding financial phenomena considering the hypotheses
under the proposed novel artificial financial market
TacIPC: Intersection- and Inversion-free FEM-based Elastomer Simulation For Optical Tactile Sensors
Tactile perception stands as a critical sensory modality for human
interaction with the environment. Among various tactile sensor techniques,
optical sensor-based approaches have gained traction, notably for producing
high-resolution tactile images. This work explores gel elastomer deformation
simulation through a physics-based approach. While previous works in this
direction usually adopt the explicit material point method (MPM), which has
certain limitations in force simulation and rendering, we adopt the finite
element method (FEM) and address the challenges in penetration and mesh
distortion with incremental potential contact (IPC) method. As a result, we
present a simulator named TacIPC, which can ensure numerically stable
simulations while accommodating direct rendering and friction modeling. To
evaluate TacIPC, we conduct three tasks: pseudo-image quality assessment,
deformed geometry estimation, and marker displacement prediction. These tasks
show its superior efficacy in reducing the sim-to-real gap. Our method can also
seamlessly integrate with existing simulators. More experiments and videos can
be found in the supplementary materials and on the website:
https://sites.google.com/view/tac-ipc
A Neural-Guided Dynamic Symbolic Network for Exploring Mathematical Expressions from Data
Symbolic regression (SR) is a powerful technique for discovering the
underlying mathematical expressions from observed data. Inspired by the success
of deep learning, recent efforts have focused on two categories for SR methods.
One is using a neural network or genetic programming to search the expression
tree directly. Although this has shown promising results, the large search
space poses difficulties in learning constant factors and processing
high-dimensional problems. Another approach is leveraging a transformer-based
model training on synthetic data and offers advantages in inference speed.
However, this method is limited to fixed small numbers of dimensions and may
encounter inference problems when given data is out-of-distribution compared to
the synthetic data. In this work, we propose DySymNet, a novel neural-guided
Dynamic Symbolic Network for SR. Instead of searching for expressions within a
large search space, we explore DySymNet with various structures and optimize
them to identify expressions that better-fitting the data. With a topology
structure like neural networks, DySymNet not only tackles the challenge of
high-dimensional problems but also proves effective in optimizing constants.
Based on extensive numerical experiments using low-dimensional public standard
benchmarks and the well-known SRBench with more variables, our method achieves
state-of-the-art performance in terms of fitting accuracy and robustness to
noise
Coronavirus accessory protein ORF3 biology and its contribution to viral behavior and pathogenesis
Coronavirus porcine epidemic diarrhea virus (PEDV) is classified in the genu
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