scholarly journals ARPA: An autonomous renderer placement algorithm in distributed multimedia fog networks with delay guarantees

2021 ◽  
Vol 2 (2) ◽  
pp. 81-108
Author(s):  
Athanasios Tsipis ◽  
Konstantinos Oikonomou
Keyword(s):  
Finite Time ◽  
Capital Expenditure ◽  
Fog Computing ◽  
Three Dimensional ◽  
Facility Location Problem ◽  
Multimedia Applications ◽  
Delay Guarantees ◽  
Continuous Service ◽  
Placement Algorithm ◽  
Finite Time Horizon

Multimedia cloud computing has emerged as a popular paradigm for the support of delay-intolerable immersive multimedia applications with high-end three-dimensional rendering. To that end, fog computing offers distributed computational offloading solutions, by positioning rendering servers in close proximity to end users promising in this way continuous service provision, that is otherwise not easily attainable under the strictly centralized cloud-only model. Yet, in order to alleviate the multimedia providers from unnecessary capital expenditure, a strategic placement approach of the servers at the fog layer must be implemented, that can effectively cope both with the network dynamics and the overall imposed deployment cost, and still adhere to the delay bounds set forth by the multimedia application. In this paper, we formally formulate the problem as a facility location problem using constrained optimization over a finite time horizon. We then theoretically analyze the minimum acceptable conditions necessary for a decentralized location of the servers, utilizing solely local information around their immediate neighborhood, that iteratively leads to better solutions. Based on the analysis, we propose a distributed algorithm, namely the Autonomous Renderer Placement Algorithm (ARPA), to address it. ARPA employs localized service relocation to shift the placement according to simple rules that designate elastic migration, replication, and complementary consolidation of the underlying renderers. Simulation results under diversified deployment scenarios, as well as trace-driven comparisons against other approaches, testify to ARPA's accountability in obeying the delay limits and fast converge in finite time slots to a placement solution that both outperforms the baseline alternatives and is close to the optimal one, rendering it suitable for scaling up and down to meet the current demands of the offered multimedia applications.

Design of finite-time guidance law based on observer and head-pursuit theory

2021 ◽  
pp. 095441002098456
Author(s):  
Chenqi Zhu
Keyword(s):  
Finite Time ◽  
Three Dimensional ◽  
Hypersonic Vehicle ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Reaching Law ◽  
Guidance Law ◽  
Fast Power ◽  
Simulation Results ◽  
Guidance Laws

In order to improve the guiding accuracy in intercepting the hypersonic vehicle, this article presents a finite-time guidance law based on the observer and head-pursuit theory. First, based on a two-dimensional model between the interceptor and target, this study applies the fast power reaching law to head-pursuit guidance law so that it can alleviate the chattering phenomenon and ensure the convergence speed. Second, target maneuvers are considered as system disturbances, and the head-pursuit guidance law based on an observer is proposed. Furthermore, this method is extended to a three-dimensional case. Finally, comparative simulation results further verify the superiority of the guidance laws designed in this article.

scholarly journals A Constrained Markovian Diffusion Model for Controlling the Pollution Accumulation

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1466
Author(s):  
Beatris Adriana Escobedo-Trujillo ◽  
José Daniel López-Barrientos ◽  
Javier Garrido-Meléndez
Keyword(s):  
Dynamic Programming ◽  
Dirichlet Problem ◽  
Stochastic Control ◽  
Finite Time ◽  
Time Horizon ◽  
Closed Loop ◽  
Programming Techniques ◽  
Pollution Accumulation ◽  
Finite Time Horizon ◽  
The Cost

This work presents a study of a finite-time horizon stochastic control problem with restrictions on both the reward and the cost functions. To this end, it uses standard dynamic programming techniques, and an extension of the classic Lagrange multipliers approach. The coefficients considered here are supposed to be unbounded, and the obtained strategies are of non-stationary closed-loop type. The driving thread of the paper is a sequence of examples on a pollution accumulation model, which is used for the purpose of showing three algorithms for the purpose of replicating the results. There, the reader can find a result on the interchangeability of limits in a Dirichlet problem.

Robust impact angle constraints guidance law with autopilot lag and acceleration saturation consideration

2018 ◽  
Vol 41 (1) ◽  
pp. 182-192 ◽  
Author(s):  
Junhong Song ◽  
Shenmin Song
Keyword(s):  
Upper Bound ◽  
Finite Time ◽  
Sliding Mode ◽  
Three Dimensional ◽  
Impact Angle ◽  
Guidance System ◽  
Control Technique ◽  
Backstepping Method ◽  
Terminal Sliding Mode ◽  
Guidance Law

In this paper, for the three-dimensional terminal guidance problem of a missile intercepting a manoeuvring target, a robust continuous guidance law with impact angle constraints in the presence of both an acceleration saturation constraint and a second-order-lag autopilot is developed. First, based on non-singular fast terminal sliding mode and adaptive control, a step-by-step backstepping method is used to design the guidance law. In the process of guidance law design, with the use of a finite-time control technique, virtual control laws are developed, a tracking differentiator is used to eliminate the ‘explosion of complexity’ problem inherent in the traditional backstepping method, and an additional system is constructed to deal with the acceleration saturation problem; its states are used for guidance law design and stability analysis. Moreover, the target acceleration is considered bounded disturbance, but the upper bound is not required to be known in advance, whereas the upper bound is estimated online by a designed adaptive law. Next, finite-time stability of the guidance system is strictly proved by using a Lyapunov method. Finally, numerical simulations are presented to demonstrate the excellent guidance performances of the proposed guidance law in terms of accuracy and efficiency.

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