基于过度自信的连续时间委托-代理模型研究

本文以有关心理学理论为依据,建立数学模型研究委托人和代理人过高估计公司信息质量条件下的连续时间委托-代理理论,并分析这种过度自信对委托-代理关系的作用机制.研究表明,最优补偿合同由两部分组成:代理人的保留财富价值和代理人在合同存续期内的努力工作成本;而次优补偿合同由四部分组成:代理人的保留财富价值、努力工作成本、风险溢价和未预期到的意外收益.委托人和代理人在公司信息方面的过度自信偏差都将提高代理成本、恶化道德风险问题.因此改善委托-代理关系的一个有效途径是,委托人自己首先要在公司信息问题上保持理性,其次是要雇佣在公司信息质量方面同样理性的代理人,使委托人和代理人双方都尽可能无偏地估计公司信息的信息价值.

论企业代理关系与会计假设

企业代理学说的提出 ,为会计理论研究提供了一种新的理论依据和分析工具。本文从代理关系的角度出发 ,通过企业中存在代理关系这一事实 ,为会计假设的成立提供事实依据。现代企业实质上是由代理关系或一系列有形或无形契约组成的集合体。代理关系在企业一定范围内的存在及其理顺是会计主体假设提出的事实依据 ,代理时间的存在及确定是会计持续经营假设提出的事实依据 ,代理期间的存在是会计期间假设的事实依据 ,而对代理责任的解除、代理绩效的考评指标确定计量单位 。

基于时间不一致性偏好的连续时间代理模型

为了构建一个更合理的最优契约模型,本文在经典的连续时间代理模型中假设委托人的时间偏好是不一致的且是成熟型的,采用拟双曲贴现函数刻画时间不一致性偏好过程.本文研究了委托人的时间偏好不一致性对委托人的值函数和最优薪金支付边界的影响.与经典的连续时间代理模型相比,本文的研究结果表明:成熟型委托人的值函数和最优薪金支付边界随时间不一致性偏好程度增大而降低.也就是说,为了弥补来自时间偏好不一致性的不确定风险,时间不一致性偏好的委托人比时间一致性偏好的委托人倾向于以一个更低的薪金更早地、更频繁地支付给代理人,使代理人更早地如实披露现金流.这表明委托人的时间不一致性偏好对最优契约会产生较大影响.

Consensus and formation control of discrete-time multi-agent systems

Consensus problems for discrete-time multi-agent systems were focused on. In order to design effective consensus protocols, which were aimed at ensuring that the concerned states of agents converged to a common value, a new consensus protocol for general discrete-time multi-agent system was proposed based on Lyapunov stability theory. For discrete-time multi-agent systems with desired trajectory, trajectory tracking and formation control problems were studied. The main idea of trajectory tracking problems was to design trajectory controller such that each agent tracked desired trajectory. For a type of formation problem with fixed formation structure, the formation structure set was introduced. According to the formation structure set, each agent can track its individual desired trajectory. Finally, simulations were provided to demonstrate the effectiveness of the theoretical results. The mlmerical results show that the states of agents converge to zero with consensus protocol, which is said to achieve a consensus asymptotically. In addition, through designing appropriate trajectory controllers, the simulation results show that agents converge to the desired trajectory asymptotically and can form different formations.

Linearly constrained SOLMS for adaptive space-time interference cancellation in STBC MIMO systems

This paper presents an adaptive linearly constrained second-order least mean-square (LC-SOLMS) algorithm for interference cancellation in space-time block coded MIMO systems with fading channels. By taking mean-output-energy (MOE) optimization method, an adaptive linear detection algorithm was built up, which can suppress multiple access interference and noise. Simulation results illustrate that the proposed algorithm has great interference cancellation capability and faster convergence performance.

Associations between walking parameters and subsequent sleep difficulty in older adults: A 2-year follow-up study

Purpose: This 2-year follow-up study aimed to examine the associations between total volume, frequency, duration, and speed of walking with subsequent sleep difficulty in older adults.Methods: A total of 800 older adults aged 65 years and over participated in the first survey in 2012 and 511 of them were followed 2 years later.The 5-item Athens Insomnia Scale(AIS-5) was used to measure sleep difficulty. Frequency, duration, and speed of outdoor walking were self-reported. Walking speed was assigned a metabolic equivalent value(MET) from 2.5 to 4.5. Total walking volume in MET-h/week was calculated as frequency × duration × speed. Negative binomial regressions were performed to examine the associations between volume and components of walking with subsequent sleep difficulty with covariates of age, sex, education, marital status, living arrangement, smoking, alcohol consumption, mental health, Charlson Index, exercise(excluding walking), and sleep difficulty at baseline.Results: Participants with low walking volume had a higher level of sleep difficulty 2 years later compared with those with high walking volume(incident rate ratios = 1.61, p = 0.004). When speed, frequency, and duration of walking were simultaneously entered into 1 model, only walking speed was significantly associated with subsequent sleep difficulty(after the model was adjusted for covariates and baseline sleep difficulty).Sensitivity analyses showed that walking duration emerged as a significant predictor among 3 walking parameters, with 2-year changes of sleep scores as dependent variable.Conclusion: Total amount of walking(especially faster walking and lasting for more than 20 min) is associated with less subsequent sleep difficulty after 2 years among older adults.

A Modified Multi-Agent System for Simple Assembly Line Balancing

In this paper, a modified multi-agent system for assembly line balancing is proposed. Each worker in the assembly line is regarded as an agent, and two neighboring agents exchange information about the allocated tasks. To balance the workload, an agent with a smaller workload sends a request message to his/her neighboring agent, who has a larger workload, to exchange tasks between them. Without any centralized control mechanism, each agent behaves to achieve their goal, which is to balance the workload. A tabu list and cooling control are also incorporated. However, the effectiveness of the previous system is limited, and the system depends on problems to be solved. As such, a modified system is proposed. In the proposed system, the cycle time is used when considering the proposal of exchange of allocated tasks instead of the task time allocated to the neighboring workers. Also, in the proposed system, the length of tabu list is determined dynamically based on the current number of possible exchanges, and the best cycle time in the search with cooling at medium speed is recorded for the second search that is finished when the current cycle time reaches the recorded cycle time. The effectiveness of the modified system is investigated by solving problems for various conditions. The results show that the proposed system is effective regardless of the problems that are encountered.

Space and Temporal Distribution Analysis of Interictal Spike in Epilepsy

Stereo-electroencephalography （SEEG） is the main investigation method for pre-surgical evaluation of patients suffering from drug-resistant partial epilepsy. SEEG signals reflect two types of paroxysmal activity： ictal activity and interictal activity or interictal spikes （IS）. The relationship between IS and ictal activity is an essential and recurrent question in epiletology. In this paper, we present a distributed and parallel architecture for space and temporal distribution analysis of IS, based on a distributed and collaborative methodology. The proposed approach exploits the SEEG data using vector analysis of the corresponding signals among multi-agents system. The objective is to present a new method to analyze and classify IS during wakefulness （W）, light sleep （LS） and deep sleep （DS） stages. Temporal and spatial relationships between IS and seizure onset zone are compared during wakefulness, light sleep and deep sleep. Results show that space and temporal distribution for real data are not random but correlated.

GROUP CONSENSUS FOR MULTIPLE NETWORKED EULER-LAGRANGE SYSTEMS WITH PARAMETRIC UNCERTAINTIES

In this paper,a group consensus problem is investigated for multiple networked agents with parametric uncertainties where all the agents are governed by the Euler-Lagrange system with uncertain parameters.In the group consensus problem,the agents asymptotically reach several different states rather than one consistent state.A novel group consensus protocol and a time-varying estimator of the uncertain parameters are proposed for each agent in order to solve the couple-group consensus problem.It is shown that the group consensus is reachable even when the system contains the uncertain parameters.Furthermore,the multi-group consensus is discussed as an extension of the couple-group consensus,and then the group consensus with switching topology is considered.Simulation results are finally provided to validate the effectiveness of the theoretical analysis.

Robust consensus of multi-agent systems with time-varying delays in noisy environment

Over the last ten years, the consensus of multi-agent systems (MAS) has received increasing attention from mechanics, mathematics, physics, engineering sciences, social sciences, and so on. It is well known that the robustness of consensus of MAS is usually determined by several key factors, including noise, time-delays, and packet drop. In this paper, we introduce a general time-delayed MAS model with noise and also further investigate its robust consensus. In particular, we prove that the proposed algorithm is robust against the bounded time-varying delays and bounded noises. The effectiveness and robustness of the proposed consensus algorithm has been validated in the classical Vicsek model with time-varying delays. And two simulation examples are also given to justify the above theoretical results. These results may have some potential applications in various fields, including mechanics, biology, and engineering sciences.

Observer-Based Event-Triggered Tracking Control of Leader-Follower Systems with Time Delay

This paper studies the tracking control of general linear multi-agent systems with out time delays. The observer-based event-triggered control schemes will be considered or with- For the conventional distributed tracking protocol, the authors will not update the relative state in continuous time, i.e., the relative state will be updated by some events which happened in discrete time. A completely decentralized event-trigger will be designed for leader-follower systems. It is shown that all followers can track the leader asymptotically by the proposed protocol, if the feedback gain matrices are designed appropriately. Numerical simulations are also provided and the results show highly consistent with the theoretical results.

Distributed Algorithm for Robust Resource Allocation with Polyhedral Uncertain Allocation Parameters

This paper studies a distributed robust resource allocation problem with nonsmooth objective functions under polyhedral uncertain allocation parameters. In the considered distributed robust resource allocation problem, the（nonsmooth） objective function is a sum of local convex objective functions assigned to agents in a multi-agent network. Each agent has a private feasible set and decides a local variable, and all the local variables are coupled with a global affine inequality constraint,which is subject to polyhedral uncertain parameters. With the duality theory of convex optimization,the authors derive a robust counterpart of the robust resource allocation problem. Based on the robust counterpart, the authors propose a novel distributed continuous-time algorithm, in which each agent only knows its local objective function, local uncertainty parameter, local constraint set, and its neighbors＇ information. Using the stability theory of differential inclusions, the authors show that the algorithm is able to find the optimal solution under some mild conditions. Finally, the authors give an example to illustrate the efficacy of the proposed algorithm.

CONSENSUS CONTROL FOR LEADER-FOLLOWING MULTI-AGENT SYSTEMS WITH MEASUREMENT NOISES

This work is concerned with consensus control for a class of leader-following multi-agentsystems (MASs).The information that each agent received is corrupted by measurement noises.Toreduce the impact of noises on consensus,time-varying consensus gains are adopted,based on whichconsensus protocols are designed.By using the tools of stochastic analysis and algebraic graph theory,asufficient condition is obtained for the protocol to ensure strong mean square consensus under the fixedtopologies.This condition is shown to be necessary and sufficient in the noise-free case.Furthermore,by using a common Lyapunov function,the result is extended to the switching topology case.

ON FORMABILITY OF LINEAR CONTINUOUS-TIME MULTI-AGENT SYSTEMS

This paper is focused on formability of multi-agent systems （MASs）. The problem is concerned with the existence of a protocol that has the ability to drive the MAS involved to the desired formation, and thus, is of essential importance in designing formation protocols. Formability of an MAS depends on several key factors： agents＇ dynamic structures, connectivity topology, properties of the desired formation and the admissible control set. Agents of the MASs considered here are described by a general continuous linear time-invariant （LTI） model. By using the matrix analysis and algebraic graph theory, some necessary and sufficient conditions on formability of LTI-MASs are obtained. These conditions characterize in some sense the relationship of formability, connectivity topology, formation properties and agent dynamics with respect to some typical and widely used admissible protocol sets.

Time-Variant Consensus Tracking Control for Networked Planar Multi-Agent Systems with Non-Holonomic Constraints

A time-variant consensus tracking control problem for networked planar multi-agent systems with non-holonomic constraints is investigated in this paper. In the time-variant consensus tracking problem, a leader agent is expected to track a desired reference input, simultaneously, follower agents are expected to maintain a time-variant formation. To solve the time-variant consensus tracking problem of planar multi-agent systems with non-holonomic constraints, a time-variant consensus tracking control strategy is designed on the basis of an unidirectional topology structure. One of main contributions of this paper is the time-variant consensus tracking protocol for general time-variant formations of planar multi-agent systems with non-holonomic constraints, the other main contribution of this paper is an active predictive control strategy, where predictions of agents are generated actively, so that the computational efficiency is improved than passive approaches. The proposed control strategy is verified by two types of time-varying formations of wheeled mobile robots, and the experimental results show that the proposed control strategy is effective for general time-variant consensus tracking problems of planar multi-agent systems with non-holonomic constraints in local and worldwide networked environments.

ON CONTROL OF STRONG CONSENSUS FOR NETWORKED AGENTS WITH NOISY OBSERVATIONS

The discrete-time first-order multi-agent networks with communication noises are under consideration. Based on the noisy observations, the consensus control is given for networks with both fixed and time-varying topologies. The states of agents in the resulting closed-loop network are updated by a stochastic approximation （SA） algorithm, and the consensus analysis for networks turns to be the convergence analysis for SA. For networks with fixed topologies, the proposed consensus control leads to consensus of agents with probability one if the graph associated with the network is connected. In the case of time-varying topologies, the similar results are derived if the graph is jointly connected in a fixed time period. Compared with existing results, the networks considered here are in a more general setting under weaker assumptions and the strong consensus is established by a simpler proof.

Tracking Consensus for Second-Order Multi-Agent Systems with Nonlinear Dynamics in Noisy Environments

This paper investigates the leader-following tracking consensus problem for second-order multi-agent sys- tems with time delays and nonlinear dynamics in noisy environments on the conditions of fixed and switching directed topologies. Based on a novel velocity decomposition technique and stochastic anaJysis, a measurement-based distributed tracking control protocol is proposed, under which all agents can track the leader in mean square. Simulation results are also given to illustrate the effectiveness of the proposed protocol.

Homogeneous Finite-Time Consensus Control for Higher-Order Multi-Agent Systems by Full Order Sliding Mode

This paper investigates the distributed finite-time consensus tracking problem for higher- order nonlinear multi-agent systems （MASs）. The distributed finite-time consensus protocol is based on full order sliding surface and super twisting algorithm. The nominal consensus control for the MASs is designed based on the geometric homogeneous finite time control technique. The chattering is avoided by designing a full order sliding surface. The switching control is constructed by integrating super twisting algorithm, hence a chattering alleviation protocol is obtained to maintain a smooth control input. The finite time convergence analysis for the leader follower network is presented by using strict Lyapunov function. Finally, the numerical simulations validate the proposed homogeneous full-order sliding mode control for higher-order MASs.

Data-Driven Leader-Follower Output Synchronization for Networked Non-Linear Multi-Agent Systems with Switching Topology and Time-Varying Delays

This paper studies the output synchronization problem for a class of networked non-linear multi-agent systems with switching topology and time-varying delays. To synchronize the outputs,a leader is introduced whose connectivity to the followers varies with time, and a novel data-driven consensus protocol based on model free adaptive control is proposed, where the reference input of each follower is designed to be the time-varying average of the neighboring agents＇ outputs. Both the case when the leader is with a prescribed reference input and the case otherwise are considered.The proposed protocol allows for time-varying delays, switching topology, and does not use the agent structure or the dynamics information implicitly or explicitly. Sufficient conditions are derived to guarantee the closed-loop stability, and conditions for consensus convergence are obtained, where only a joint spanning tree is required. Numerical simulations and practical experiments are conducted to demonstrate the effectiveness of the proposed protocol.

Finite Time Consensus Problem for Multiple Non-Holonomic Agents with Communication Delay

In this paper, finite time consensus problem is discussed for multiple non-holonomic mobile agents with constant communication delay. The objective is to design non-smooth distributed control laws such that multiple non-holonomic mobile agents can be all in agreement within any given finite time larger than communication delay. The authors propose a novel switching control strategy with the help of Lyapunov-based method and graph theory.