An official website of the United States government
Significance Nervous systems use highly effective layered architectures in the sensorimotor control system to minimize the harmful effects of delay and inaccuracy in biological components. To study what makes effective architectures, we develop a theoretical framework that connects the component speed–accuracy trade-offs (SATs) with system SATs and characterizes the system performance of a layered control system. We show that diversity in layers (e.g., planning and reflex) allows fast and accurate sensorimotor control, even when each layer uses slow or inaccurate components. We term such phenomena “diversity-enabled sweet spots (DESSs).” DESSs explain and link the extreme heterogeneities in axon sizes and numbers and the resulting robust performance in sensorimotor control.
more »
« less
An Introduction to Protocol Driven Resilience
The structure of engineered infrastructure systems can be represented by a layered architecture. The relationship between physical components of many types of these systems has been well studied and modelled. The engineered design of these systems can account for some of their characteristics such as robustness, flexibility, reliability. We believe that the resilience, or adaptive capacity, of these systems cannot be described merely by studying the engineered components of such systems. This requires studying what we refer to as the protocol layers. The protocol layer is where humans interact with the engineered elements of the system through the collection and processing of information with the aim of producing a control activity on the system. In the first part of this study we look at several formulations of a generic layered transportation system, to discuss the importance of protocols in adaptive capability. In the second part, we take a brief historical look at an important American intermodal inland waterway transportation system, The Tennessee Valley Authority. From this system we extract some basic protocol layers and discuss how the success or failure of this system has resulted from these protocol layers.
more »
« less
- PAR ID:
- 10148899
- Date Published:
- Journal Name:
- Proceedings of the 29th European Safety and Reliability Conference
- Page Range / eLocation ID:
- 145 to 156
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Over the past decade, the field of two-dimensional (2D) layered materials has surged, promising a new platform for studying diverse physical phenomena that are scientifically intriguing and technologically relevant. Contacts are the communication links between these 2D materials and the three-dimensional world for probing and harnessing their exquisite electronic properties. However, fundamental challenges related to contacts often limit the ultimate performance and potential of 2D materials and devices. This article provides a comprehensive overview of the basic understanding and importance of contacts to 2D materials and various strategies for engineering and improving them. In particular, we elucidate the phenomenon of Fermi level pinning at the metal/2D contact interface, the Schottky versus Ohmic nature of the contacts and various contact engineering approaches including interlayer contacts, phase engineered contacts, and basal versus edge plane contacts, among others. Finally, we also discuss some of the relatively under-addressed and unresolved issues, such as contact scaling, and conclude with a future outlook.more » « less
-
The air transportation system connects the world through the transport of goods and people. However, operational inefficiencies such as flight delays and cancellations are prevalent, resulting in economic and environmental impacts. In the first part of this article, we review recent advances in using network analysis techniques to model the interdependencies observed in the air transportation system and to understand the role of airports in connecting populations, serving air traffic demand, and spreading delays. In the second part, we present some of our recent work on using operational data to build dynamical system models of air traffic delay networks. We show that Markov jump linear system models capture many of the salient characteristics of these networked systems. We illustrate how these models can be validated and then used to analyze system properties such as stability and to design optimal control strategies that limit the propagation of disruptions in air traffic networks.more » « less
-
| The relentless demand for data in our society has driven the continuous evolution of wireless technologies to enhance network capacity. While current deployments of 5G have made strides in this direction using massive multiple-input–multiple-output (MIMO) and millimeter-wave (mmWave) bands, all existing wireless systems operate in a half-duplex (HD) mode. Full-duplex (FD) wireless communication, on the other hand, enables simultaneous transmission and reception (STAR) of signals at the same frequency, offering advantages such as enhanced spectrum efficiency, improved data rates, and reduced latency. This article presents a comprehensive review of FD wireless systems, with a focus on hardware design, implementation, cross-layered considerations, and applications. The major bottleneck in achieving FD communication is the presence of self-interference (SI) signals from the transmitter (TX) to the receiver, and achieving SI cancellation (SIC) with real-time adaption is critical for FD deployment. The review starts by establishing a system-level understanding of FD wireless systems, followed by a review of the architectures of antenna interfaces and integrated RF and baseband (BB) SI cancellers, which show promise in enabling low-cost, small-form-factor, portable FD systems. We then discuss digital cancellation techniques, including digital signal processing (DSP)- and learning-based algorithms. The challenges presented by FD phased-array and MIMO systems are discussed, followed by system-level aspects, including optimization algorithms, opportunities in the higher layers of the networking protocol stack, and testbed integration. Finally, the relevance of FD systems in applications such as next-generation (xGmore » « less
-
As transportation systems grow in complexity, analysts need sophisticated tools to understand travelers’ decision-making and effectively quantify the benefits of the proposed strategies. The transportation community has developed integrated demand–supply models to capture the emerging interactive nature of transportation systems, serve diverse planning needs, and encompass broader solution possibilities. Recently, utilizing advances in Machine Learning (ML) techniques, researchers have also recognized the need for different computational models capable of fusing/analyzing different data sources. Inspired by this momentum, this study proposes a new modeling framework to analytically bridge travel demand components and network assignment models with machine learning algorithms. Specifically, to establish a consistent representation of such aspects between separate system models, we introduce several important mathematical programming reformulation techniques—variable splitting and augmented Lagrangian relaxation—to construct a computationally tractable nonlinear unconstrained optimization program. Furthermore, to find equilibrium states, we apply automatic differentiation (AD) to compute the gradients of decision variables in a layered structure with the proposed model represented based on computational graphs (CGs) and solve the proposed formulation through the alternating direction method of multipliers (ADMM) as a dual decomposition method. Thus, this reformulated model offers a theoretically consistent framework to express the gap between the demand and supply components and lays the computational foundation for utilizing a new generation of numerically reliable optimization solvers. Using a small example network and the Chicago sketch transportation network, we examined the convergency/consistency measures of this new differentiable programming-based optimization structure and demonstrated the computational efficiency of the proposed integrated transportation demand and supply models.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.3850/978-981-11-2724-3_1026-cd
