Identifying critical features of complex systems under prior known conditions

Identifying critical activities or subsystems is usually the first step in reducing the complexity of systems. The design structure matrix (DSM) is a highly effective tool for managing a complex system by identifying and prioritizing critical activities. However, a standard DSM has limited application to systems with prior known conditions or practical application constraints. In this paper, we develop a conditional DSM method in order to identify critical features under some prior known conditions or existing constraints. This method of analysis is applied to a wafer fabrication case to verify its utility. In addition, this paper aims to make the DSM far more effective and broad in its application.     

Intelligent autonomous systems

An international conference entitled “Intelligent Autonomous Systems” was held in Amsterdam, The Netherlands from 8–11 December 1986.Following the “Introductory Address” presented by chairman L.O. Hertzberger (University of Amsterdam, The Netherlands) there were eight invited papers which considered the theoretical and practical aspects of designing and operating autonomous systems. A further sixty-two papers were presented which provided an in-depth analysis of intelligent autonomous systems.We present below a report on the lectures delivered at the conference.     

Imposing limits on autonomous systems

Abstract

Our present era is witnessing the genesis of a sea-change in the way that advanced technologies operate. Amongst this burgeoning wave of untrammelled automation there is now beginning to arise a cadre of ever-more independent, autonomous systems. The degree of interaction between these latter systems with any form of human controller is becoming progressively more diminished and remote; and this perhaps necessarily so. Here, I advocate for human-centred and human favouring constraints to be designed, programmed, promulgated and imposed upon these nascent forms of independent entity. I am not sanguine about the collective response of modern society to this call. Nevertheless, the warning must be voiced and the issue debated, especially among those who most look to mediate between people and technology.

Practitioner Summary: Practitioners are witnessing the penetration of progressively more independent technical orthotics into virtually all systems’ operations. This work enjoins them to advocate for sentient, rational and mindful human-centred approaches towards such innovations. Practitioners need to place user-centred concerns above either the technical or the financial imperatives which motivate this line of progress.     

Autonomous security for autonomous systems

The Internet’s interdomain routing protocol, BGP, supports a complex network of Autonomous Systems which is vulnerable to a number of potentially crippling attacks. Several promising cryptography-based solutions have been proposed, but their adoption has been hindered by the need for community consensus, cooperation in a public key infrastructure (PKI), and a common security protocol. Rather than force centralized control in a distributed network, this paper examines distributed security methods that are amenable to incremental deployment. Typically, such methods are less comprehensive and not provably secure. The paper describes a distributed anomaly detection and response system that provides comparable security to cryptographic methods and has a more plausible adoption path. Specifically, the paper makes the following contributions: (1) it describes pretty good BGP (PGBGP), whose security is comparable (but not identical) to secure origin BGP; (2) it gives theoretical proofs on the effectiveness of PGBGP; (3) it reports simulation experiments on a snapshot of the Internet topology annotated with the business relationships between neighboring networks; (4) it quantifies the impact that known exploits could have on the Internet; and (5) it determines the minimum number of ASes that would have to adopt a distributed security solution to provide global protection against these exploits. Taken together these results explore the boundary between what can be achieved with provably secure centralized security mechanisms for BGP and more distributed approaches that respect the autonomous nature of the Internet.     

Valves for autonomous capillary systems

Autonomous capillary systems (CSs) are microfluidic systems inside which liquids move owing to capillary forces. CSs can in principle bring the high-performances of microfluidic-based analytical devices to near patient and environmental testing applications. In this paper, we show how wettable capillary valves can enhance CSs with novel functionalities, such as delaying and stopping liquids in microchannels. The valves employ an abruptly changing geometry of the flow path to delay a moving liquid filling front in a wettable microchannel. We show how to combine delay valves with capillary pumps, prevent shortcuts of liquid along the corners of microfluidic channels, stop liquids filling microchannels from a few seconds to over 30 min, trigger valves using two liquid fronts merging, and time a liquid using parallel microfluidic paths converging to a trigger valve. All together, these concepts should add functionality to passive microfluidic systems without departing from their initial simplicity of use. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Resource-bounded sensing and planning in autonomous systems

This paper is concerned with the implications of limited computational resources and uncertainty on the design of autonomous systems. To address this problem, we redefine the principal role of sensor interpretation and planning processes. Following Agre and Chapman's plan-as-communication approach, sensing and planning are treated as computational processes that provide information to an execution architecture and thus improve the overall performance of the system. We argue that autonomous systems must be able to trade off the quality of this information with the computational resources required to produce it. Anytime algorithms, whose quality of results improves gradually as computation time increases, provide useful performance components for time-critical sensing and planning in robotic systems. In our earlier work, we introduced a compilation scheme for optimal composition of anytime algorithms. This paper demonstrates the applicability of the compilation technique to the construction of autonomous systems. The result is a flexible approach to construct systems that can operate robustly in real-time by exploiting the tradeoff between time and quality in planning, sensing and plan execution.     

Identifying subsystems in information systems analysis

The paper discusses five main criteria for the construction of subsystems of an information system. The criteria are flexibility/changeability, separability, comprehensibility, integrability and data usage and/or creation. Two procedures based on the data usage and/or creation criterion are described. These procedures are used to determine the composition of each subsystem, keeping the other four criteria in focus. An application of the methodology to a sample data is presented.     

Identifying object isomerism in multidatabase systems

In a multidatabase system that consists of object databases, the same real-world entity can be stored as objects in different databases with incompatible object identifiers. How to identify and integrate these objects representing the same entities such that (a) object duplication in the query result can be avoided, (b) information for the entity can be gathered, and (c) the specialization of multiple classes can be built is an important issue to provide a well structured global object schema and a more informative query result. In this paper, we extend our results on probabilistic query processing and joining relations on incompatible keys to solve the problem. Various data and schema conflicts such as missing data, inconsistent data and domain mismatch which may exist in classes from different databases are considered in the process of identification.Recommended by: Amit Sheth     

Simulating belief systems of autonomous agents

Autonomous agents in computer simulations do not have the usual mechanisms to acquire information as do their human counterparts. In many such simulations, it is not desirable that the agent have access to complete and correct information about its environment. We examine how imperfection in available information may be simulated in the case of autonomous agents. We determine probabilistically what the agent may detect, through hypothetical sensors, in a given situation. These detections are combined with the agent's knowledge base to infer observations and beliefs. Inherent in this task is a degree of uncertainty in choosing the most appropriate observation or belief. We describe and compare two approaches — a numerical approach and one based on defeasible logic — for simulating an appropriate belief in light of conflicting detection values at a given point in time. We discuss the application of this technique to autonomous forces in combat simulation systems.     

Current trends in the development of intelligent unmanned autonomous systems

Intelligent unmanned autonomous systems are some of the most important applications of artificial intelligence (AI). The development of such systems can significantly promote innovation in AI technologies. This paper introduces the trends in the development of intelligent unmanned autonomous systems by summarizing the main achievements in each technological platform. Furthermore, we classify the relevant technologies into seven areas, including AI technologies, unmanned vehicles, unmanned aerial vehicles, service robots, space robots, marine robots, and unmanned workshops/intelligent plants. Current trends and developments in each area are introduced.     

Predicate caching for data-intensive autonomous systems

Predicate caching is a powerful memory caching technique especially suitable for a class of applications called autonomous systems. These systems can act according to presupplied logic that defines predictable, repetitive data access requests. This class includes rule-based systems, expert systems, logic programs, active database systems, database integrity constraints, triggers, alerters, and autonomous intelligent agents. Some of these systems are data-intensive. Predicate caching improves memory utilization and response time of repetitive queries by prestoring partial results in primary memory, which results in minimizing secondary storage access. With predicate caching, a system applies a predicate to the data on its way from one memory device to another. A predicate, in this context, is any predetermined calculation made by a program. I describe the predicate caching technique and, specifically, the page-predicate approach that I developed to resolve problems of cache partitioning, management, and optimization. The work discussed is based on simulation experiments I devised, programmed, and conducted     

Self-boosting first-order autonomous learning neuro-fuzzy systems

In this paper, a detailed mathematical analysis of the optimality of the premise and consequent parts of the recently introduced first-order Autonomous Learning Multi-Model (ALMMo) neuro-fuzzy system is conducted. A novel self-boosting algorithm for structure- and parameter-optimization is, then, introduced to the ALMMo, which results in the self-boosting ALMMo (SBALMMo) neuro-fuzzy system. By minimizing the objective functions with the previously collected data, the SBALMMo is able to optimize its system structure and parameters in few iterations. Numerical examples based benchmark datasets and real-world problems demonstrate the effectiveness and validity of the SBALMMo, and show the strong potential of the proposed approach for real applications.     

Identifying the parameters of elliptic-pseudoparabolic distributed systems

Calculation algorithms for the realization of gradient methods based on the solution to direct and adjoint problems in weak formulations are proposed for a number of inverse complex problems of estimating the parameters of multicomponent elliptic-pseudoparabolic distributed systems. The proposed approach makes it unnecessary to construct Lagrange functionals in explicit form and to use Green functions.     

Practical verification of decision-making in agent-based autonomous systems

We present a verification methodology for analysing the decision-making component in agent-based hybrid systems. Traditionally hybrid automata have been used to both implement and verify such systems, but hybrid automata based modelling, programming and verification techniques scale poorly as the complexity of discrete decision-making increases making them unattractive in situations where complex logical reasoning is required. In the programming of complex systems it has, therefore, become common to separate out logical decision-making into a separate, discrete, component. However, verification techniques have failed to keep pace with this development. We are exploring agent-based logical components and have developed a model checking technique for such components which can then be composed with a separate analysis of the continuous part of the hybrid system. Among other things this allows program model checkers to be used to verify the actual implementation of the decision-making in hybrid autonomous systems.     

Self-priming of liquids in capillary autonomous microfluidic systems

We present a numerical approach to the capillary rise dynamics in microfluidic channels of complex 3D geometries. In order to optimize the delivery of specific biological fluids to target regions in microfluidic capillary autonomous systems (CAS), we analyze self-priming of liquid water into a microfluidic device consisting of a microfluidic channel that feeds a rectangular microfluidic cavity trough an appropriately designed micro-chamber. The target performance criteria in our optimization are (1) fast and complete wetting of the cavity bottom while (2) minimizing the probability of trapping air bubble in the device. The numerical model is based on the lattice Boltzmann method (LBM) and a three-dimensional single-component multiple-phase (SCMP) scheme. By using a parallel implementation of this algorithm, we investigate the physical processes related to the invasion of the liquid–gas interfaces in rectangular cavities at different liquid–solid contact angle and shapes of the transition micro-chamber. The numerical results has successfully captured important qualitative and some key quantitative effects of the liquid–solid contact angle, the roughness of the cavity edges, the depth of the holes and shape of the micro-chambers. Moreover, we present and validate experimentally simple geometrical optimizations of the microfluidic device that ensure the complete filling the microfluidic cavity with liquid. Critical parameters related to the overall priming time of the device are presented as well.     

Identifying and reducing critical lag in finite element simulations

End-to-end lag time can undermine the effectiveness of interactive displays. Analyzing lag components for an FES indicated that simulation time is the critical component     

Lyapunov stability of n-D strongly autonomous systems

In this article we look into stability properties of strongly autonomous n-D systems, i.e. systems having finite-dimensional behaviour. These systems are known to have a first-order representation akin to 1-D state-space representation; we consider our systems to be already in this form throughout. We first define restriction of an n-D system to a 1-D subspace. Using this we define stability with respect to a given half-line, and then stability with respect to collections of such half-lines: proper cones. Then we show how stability with respect to a half-line, for the strongly autonomous case, reduces to a linear combination of the state representation matrices being Hurwitz. We first relate the eigenvalues of this linear combination with those of the individual matrices. With this we give an equivalent geometric criterion in terms of the real part of the characteristic variety of the system for half-line stability. Then we extend this geometric criterion to the case of stability with respect to a proper cone. Finally, we look into a Lyapunov theory of stability with respect to a proper cone for strongly autonomous systems. Each non-zero vector in the given proper cone gives rise to a linear combination of the system matrices. Each of these linear combinations gives a corresponding Lyapunov inequality. We show that the system is stable with respect to the proper cone if and only if there exists a common solution to all of these Lyapunov inequalities.