37 research outputs found
Dynamic Event-Triggered Consensus of Multi-agent Systems on Matrix-weighted Networks
This paper examines event-triggered consensus of multi-agent systems on
matrix-weighted networks, where the interdependencies among higher-dimensional
states of neighboring agents are characterized by matrix-weighted edges in the
network. Specifically, a distributed dynamic event-triggered coordination
strategy is proposed for this category of generalized networks, in which an
auxiliary system is employed for each agent to dynamically adjust the trigger
threshold, which plays an essential role in guaranteeing that the triggering
time sequence does not exhibit Zeno behavior. Distributed event-triggered
control protocols are proposed to guarantee leaderless and leader-follower
consensus for multi-agent systems on matrix-weighted networks, respectively. It
is shown that that the spectral properties of matrix-valued weights are crucial
in event-triggered mechanism design for matrix-weighted networks. Finally,
simulation examples are provided to demonstrate the theoretical results
On Stability and Consensus of Signed Networks: A Self-loop Compensation Perspective
Positive semidefinite is not an inherent property of signed Laplacians, which
renders the stability and consensus of multi-agent system on undirected signed
networks intricate. Inspired by the correlation between diagonal dominance and
spectrum of signed Laplacians, this paper proposes a self-loop compensation
mechanism in the design of interaction protocol amongst agents and examines the
stability/consensus of the compensated signed networks. It turns out that
self-loop compensation acts as exerting a virtual leader on these agents that
are incident to negative edges, steering whom towards origin. Analytical
connections between self-loop compensation and the collective behavior of the
compensated signed network are established. Necessary and/or sufficient
conditions for predictable cluster consensus of signed networks via self-loop
compensation are provided. The optimality of self-loop compensation is
discussed. Furthermore, we extend our results to directed signed networks where
the symmetry of signed Laplacian is not free. Simulation examples are provided
to demonstrate the theoretical results
Vector-valued Privacy-Preserving Average Consensus
Achieving average consensus without disclosing sensitive information can be a
critical concern for multi-agent coordination. This paper examines
privacy-preserving average consensus (PPAC) for vector-valued multi-agent
networks. In particular, a set of agents with vector-valued states aim to
collaboratively reach an exact average consensus of their initial states, while
each agent's initial state cannot be disclosed to other agents. We show that
the vector-valued PPAC problem can be solved via associated matrix-weighted
networks with the higher-dimensional agent state. Specifically, a novel
distributed vector-valued PPAC algorithm is proposed by lifting the agent-state
to higher-dimensional space and designing the associated matrix-weighted
network with dynamic, low-rank, positive semi-definite coupling matrices to
both conceal the vector-valued agent state and guarantee that the multi-agent
network asymptotically converges to the average consensus. Essentially, the
convergence analysis can be transformed into the average consensus problem on
switching matrix-weighted networks. We show that the exact average consensus
can be guaranteed and the initial agents' states can be kept private if each
agent has at least one "legitimate" neighbor. The algorithm, involving only
basic matrix operations, is computationally more efficient than
cryptography-based approaches and can be implemented in a fully distributed
manner without relying on a third party. Numerical simulation is provided to
illustrate the effectiveness of the proposed algorithm
Case report: Fully endoscopic microvascular decompression for glossopharyngeal neuralgia
With the advances in endoscopic technology, endoscopy is widely used in many neurosurgical procedures, such as microvascular decompression, which is an effective method to treat glossopharyngeal neuralgia, trigeminal neuralgia, and facial spasm. The purpose of this study was to determine the efficacy of fully endoscopic microvascular decompression in the treatment of glossopharyngeal neuralgia. We managed a patient with glossopharyngeal neuralgia in our department, whose main clinical manifestation was recurrent left ear and facial pain for 3 years. The patient underwent a fully endoscopic microvascular decompression. The pain in the left ear and face was significantly relieved postoperatively, and there was no recurrence at the 6-month follow-up evaluation. We describe a case of glossopharyngeal neuralgia that was successfully treated by fully endoscopic microvascular decompression, which showed that endoscopy has advantages in microvascular decompression, and fully endoscopic microvascular decompression is an effective method for glossopharyngeal neuralgia
Endoscopic endonasal surgery for non-invasive pituitary neuroendocrinology tumors with incomplete pseudocapsule
BackgroundPituitary neuroendocrinology tumors (PitNETs) with pseudocapsule can be effectively removed by the pseudocapsule-based extracapsular resection technique. In the areas without pseudocapsule, the tumor cells can spread into the adjacent tissues at the cellular level, which brings a great challenge to achieving total tumor resection.MethodsOur surgical strategy for PitNETs with an incomplete pseudocapsule is to combine the pseudocapsule-based extracapsular resection technique with the intensive excision technique for the removal of the tumor. Specifically, the pseudocapsule-based extracapsular resection technique is applied in the areas with pseudocapsule, while in the areas without pseudocapsule, the intensive excision technique bounded by adjacent normal structures is adopted. Moreover, a pathological examination was performed to determine the situations of pseudocapsule and tumor cell remnant.ResultsAll growth hormone-secreting PitNETs achieved biochemical remission after surgery. There was no deterioration of pituitary functions postoperatively, and the preoperative hypopituitarism had improved in all patients postoperatively. In total, two cases suffered a transient diabetes insipidus, and intraoperative cerebrospinal fluid leakage was observed in two cases but no postoperative cerebrospinal fluid leakage in all cases. There was no recurrence during the follow-up. The fragmental pseudocapsule and small tumor remnants were found in the majority of suspicious tissues by histological staining.ConclusionThe effectiveness and safety of the surgical strategy were preliminarily explored for removing PitNETs without incomplete pseudocapsules. In overview, the pseudocapsule-based extracapsular resection technique is applied in areas with pseudocapsule, while the intensive excision bounded by adjacent normal structures is adopted in other areas
Research on Friction and Wear Properties of Rubber Composites by Adding Glass Fiber during Mixing
GF/rubber composites have sound insulation characteristics, heat resistance, good corrosion resistance, and high mechanical strength. The compounding machine’s long working hours will inevitably wear the metal on the end face of the compounding machine. The wear of the end face metal will increase the gap between the chamber and the end face, which will lead to material leakage, reduce the mixing effect, and eventually affect the performance of GF/rubber composites. To ensure the implementation of GF/rubber composites, it is necessary to study the frictional wear behavior of GF/rubber composites on metals. In this paper, the effect of blending rubber with different amounts of GF on the frictional wear of metal on the end face was analyzed from the perspective of the formulation process, and the ratio of corrosion wear and abrasive wear was calculated for the first time
Bearing Characteristics of Multi-Wing Pile Foundations under Lateral Loads in Dapeng Bay Silty Clay
This study provides a theoretical basis for reinforcement of the soil around multi-wing piles. Limit analysis was used to determine the ultimate lateral capacity (ULC) of three- and four-wing piles in Dapeng Bay silty clay. The effects of the pile–soil interaction coefficient α, wing width Bw, and lateral-load direction β on the ULC of the pile and the shear plastic zone range of the surrounding soil were analyzed. The normalized ULC of the three-wing pile decreased when the wing–diameter ratio increased. When Bw was 0.15 m and α was 0.4, the ULC of the four-wing pile was 19% higher than that of the three-wing pile. As β increased, the normalized ULC of the four-wing pile decreased, whereas that of the three-wing pile went through a minimum at 30°. The size of the soil shear plastic ring did not depend on α for either pile type; it increased around the three-wing (but not the four-wing) pile with changes in β. However, there was also a double plastic ring of broken soil around the four-wing pile. The four-wing pile had a more symmetrical influence on the soil around the pile than the three-wing pile