Integrity Constraints Research Articles

H ∞ negative imaginary static output feedback controller for low frequency networked control systems

In this paper, an H ∞ negative imaginary static output feedback (SOF) controller is designed for a low frequency (LF) networked control system (NCS) with time-delays. A difference operator is introduced to deal with the time-delays in a feedback configuration via integral quadratic constraints (IQCs). Both H ∞ performance and negative imaginariness are analysed via LF IQCs and a generalised Kalman–Yakubovich–Popov (GKYP) lemma. A two-stage algorithm is presented to obtain the H ∞ negative imaginary SOF controller for the LF NCS with time-delays. Simulation results are given to show the effectiveness and superiority of the H ∞ negative imaginary SOF controller.

The Shapley Value in Database Management

Attribution scores can be applied in data management to quantify the contribution of individual items to conclusions from the data, as part of the explanation of what led to these conclusions. In Artificial Intelligence, Machine Learning, and Data Management, some of the common scores are deployments of the Shapley value, a formula for profit sharing in cooperative game theory. Since its invention in the 1950s, the Shapley value has been used for contribution measurement in many fields, from economics to law, with its latest researched applications in modern machine learning. Recent studies investigated the application of the Shapley value to database management. This article gives an overview of recent results on the computational complexity of the Shapley value for measuring the contribution of tuples to query answers and to the extent of inconsistency with respect to integrity constraints. More specifically, the article highlights lower and upper bounds on the complexity of calculating the Shapley value, either exactly or approximately, as well as solutions for realizing the calculation in practice.

Modeling, manipulating and evolving hybrid polystores with HyDRa

Data-intensive system evolution is a complex and error-prone process, as most evolution scenarios impact several interdependent artefacts such as the application code, the data structures or data instances. This process is becoming even more challenging with the emergence of heterogeneous database architectures, commonly called hybrid polystores, that rely on a combination of several, possibly overlapping relational and NoSQL databases. This paper presents HyDRa, a framework aiming to facilitate the design, the manipulation and evolution of polystores thanks to (1) a novel modeling language representing conceptually and physically the databases and (2) an automatically generated conceptual data access API (Application Programming Interface). HyDRa automatically enforces cross-database data integrity constraints, does not require developers to master multiple data models and query languages and protect application code from schema and data reconfiguration changes.

Robustness analysis of gain‐scheduled Model Predictive Control for Linear Parameter Varying systems: An Integral Quadratic Constraints approach

AbstractIn this paper, we evaluate the robustness qualities of Model Predictive Control (MPC) algorithms applied for Linear Parameter Varying (LPV) systems. Specifically, we analyze gain‐scheduled LPV MPC schemes, that is, those that use model predictions based on the LPV scheduling variables available at each sampling instant. Accordingly, we extend previous results on finite‐horizon robustness analysis of linear time‐variant (LTV) systems, employing Integral Quadratic Constraints (IQCs) to describe the input‐output behavior of prediction uncertainties. We provide two main novelties in our formulation: (i) we propose a parameter‐dependent Karush–Kuhn–Tucker (KKT) inequality to describe the existence and feasibility of the LPV MPC control inputs; and (ii) we model the uncertainties that arise due to the unavailability of the scheduling trajectory along the prediction horizon as a bounded interconnection in the form of a Linear Fractional Transformation (LFT). Accordingly, we use dissipativity arguments (‐hard IQCs) in order to compute robust induced gains of the closed‐loop system (specifically, the and ‐to‐Euclidean metrics), taking into account the MPC prediction uncertainties. We also generate the set of reachable states from a given initial condition. A benchmark example is used to illustrate the proposed analysis procedure.

ON THE PROPERTIES OF THE SET OF TRAJECTORIES OF THE NONLINEAR CONTROL SYSTEM WITH QUADRATIC INTEGRAL CONSTRAINT ON THE CONTROL FUNCTIONS

In this paper the control system described by a nonlinear differential equation is studied. It is assumed that the control functions have a quadratic integral constraint, more precisely, the admissible control functions are chosen from the ellipsoid of the space \(L_2([t_0,\theta];\mathbb{R}^m)\). Different properties of the set of trajectories are investigated. It is proved that a small perturbation of the set of control functions causes also appropriate small perturbation of the set of trajectories. It is also shown that the set of trajectories has a small change if along with the integral constraint on the control functions, a sufficiently large norm type geometric constraint on the control functions is introduced. It is established that every trajectory is robust with respect to the fast consumption of the remaining control resource, and hence every trajectory of the system can be approximated by a trajectory generated by full consumption of the total control resource.

Electric‐Dipole Gated Two Terminal Phototransistor for Charge‐Coupled Device

AbstractThe demand for charge‐coupled device (CCD) imagers has surged exponentially during the last decade owing to their exceptionally high quality and low noise imaging. However, they are still confronting the performance constraints of high operation power, low speed, and limited charge integration. Here, the electric‐dipole gated phototransistor operation without external gate bias is reported by using high‐k HfO2 dielectric material. The electrostatic coupling of photogenerated charges from the Si with the graphene channel through a 10 nm HfO2 layer is demonstrated. The device exhibits remarkable performance in the broadband spectrum (266–1342 nm) at low drain bias voltage. The high values of responsivity, external quantum efficiency, and detectivity of 3.7 × 103 A W−1, 0.72 × 104, and 6.20 × 1013 cmHz½ W−1, respectively, for 800 nm wavelength and 3.3 × 103 A W−1, 1.31 × 104, and 5.61 × 1013 cmHz½ W−1, respectively, for 400 nm wavelength without gate are achieved. This discovery may potentially eliminate the requirement for gate terminals from commercial CCD devices. The power efficient features of this gateless image sensor can be fabricated at the industrial scale for the future machine vision market.

IQC based analysis and estimator design for discrete-time systems affected by impulsive uncertainties

We propose novel quadratic performance tests for linear discrete-time impulsive systems based on viewing these systems as feedback interconnections of some non-impulsive linear system with an impulsive operator. In order to systematically analyze such interconnections, we employ the framework of integral quadratic constraints and propose novel constraints of this kind for capturing the behavior of the involved impulsive operator. As a major benefit, the modularity of this framework permits seamless extensions to interconnections affected by heterogeneous uncertainties in a straightforward fashion. This contrasts with alternative approaches which are based on capturing the system’s impulsive behavior by means of a clock. Building upon the developed analysis criteria, we characterize the existence of non-impulsive estimators for such impulsive interconnections in a lossless fashion and in terms of linear matrix inequalities. Finally, our approach is illustrated by means of several numerical examples.

Shift Symmetries and AdS/CFT

Massive fields on anti-de Sitter (AdS) space enjoy galileon-like shift symmetries at particular values of their masses. We explore how these shift symmetries are realized through the boundary conformal field theory (CFT), at the level of the 2-point functions. In the alternate quantization scheme in which the dual conformal field gets the smaller ∆− conformal dimension, the shift symmetry is realized as a gauge symmetry in the dual CFT, so that only shift invariant operators are true conformal primary fields. In the standard quantization scheme the shift symmetry acts on the source, leading to Ward identities that take the form of integral constraints.

Finite element approximation of optimal control problem with integral fractional Laplacian and state constraint

Finite element approximation of optimal control problem with integral fractional Laplacian and state constraint

Sufficient Solvability Conditions for the Problem of Pursuit under an Impulse Action

The article considers a linear differential pursuit game under the condition that an integral constraint is imposed on the evader’s control and the pursuer uses an impulse control. These impulse actions on the object are made at predetermined time points, and the corresponding control is represented using the Dirac delta function. The article studies linear conflicts described by a system of ordinary differential equations whose trajectories have jumps at certain times. The terminal set is represented by a cylinder in an n-dimensional Euclidean space. The problem is solved using the resolving function method. The fact that the lower bound is reached is proved using the theory of support functions. As a result, the quasi-strategy is replaced by an almost stroboscopic strategy and a method for building this strategy is presented. An example of a nonlinear right-hand side is given.

A Modified Method of Resolving Functions for Game Control Problems with Integral Constraints

A Modified Method of Resolving Functions for Game Control Problems with Integral Constraints

Controllability and optimal speed-in-action of linear systems with boundary conditions

The paper proposes a method for solving the problem of optimal performance for linear systems of ordinary differential equations in the presence of phase and integral restrictions, when the initial and final states of the system are elements of given convex closed sets, taking into account the control value restriction. The presented work refers to the mathematical theory of optimal processes from L.S. Pontryagin and his students and the theory of controllability of dynamic systems from R.E. Kalman. We study the problem of optimal speed for linear systems with boundary conditions from given sets close to the presence of phase and integral constraints, as well as constraints on the control value. A theory of the boundary value problem has been created and a method for solving it based on the study of solvability and the construction of a general solution to the Fredholm integral equation of the first kind has been developed. The main results are the distribution of all controls’ sets, each subject of which transfers the trajectory of the system from any initial state to any final state; reducing the initial boundary point to a special initial optimal control problem; constructing a system of algorithms for the gamma-algorithm study on the derivation of problems and rational execution with restrictions on the solution of the optimal speed’ problem with restrictions.

Determining Why Facilities Management has been Conservative in Adopting Data Analytics

The necessity for data analytics in facilities management is increasing due to the complexity of modern-days organisational requirements in the 21st century. Despite the emergence of data analytics that has benefited various businesses and industrial sectors, the facilities management sector has been conservative in adopting the technology. This would lead to severe challenges for FM to achieve continuous improvement and revolutionise the management of the facilities through the implementation of IR4.0. Thus, this paper aims to determine why facilities management service providers seem to be struggling to adopt data analytics in their operations. A literature review was carried out on existing literature on the topic. The selected articles were then critically evaluated for their quality and relevance to the subject matter and the findings were synthesised and summarised. The result suggests that facilities management service providers faced three challenges that contribute to their conservative adoption of data analytics in facilities management which are technology integration, organisational inefficiency, and financial constraints. The findings of this study could help to better understand why the facilities management sector has been conservative in adopting data analytics which could pave a path to identifying ways for facilities management service providers to adopt data analytics in their operations.

Computation of invariant sets for discrete‐time uncertain systems

AbstractThis article proposes novel methods for the computation of state and output bounding sets for discrete‐time uncertain systems. The systems under consideration are formed from the interconnection of a nominal linear time‐invariant system and an uncertainty operator that is known to lie within a prespecified set. The set of allowable uncertainties is described by a pointwise integral quadratic constraint (IQC), that is, a quadratic constraint that holds for all time‐steps. Examples of pointwise IQCs characterizing common uncertainty sets are provided. The exogenous input to the system is assumed to lie in a given polytope or ellipsoid for all time‐steps. The proposed methods are illustrated via an example.

Unsupervised synthesis of realistic coronary artery X-ray angiogram.

Medical image analysis suffers from a sparsity of annotated data necessary in learning-based models. Cardiorespiratory simulators have been developed to counter the lack of data. However, the resulting data often lack realism. Hence, the proposed method aims to synthesize realistic and fully customizable angiograms of coronary arteries for the training of learning-based biomedical tasks, for cardiologists performing interventions, and for cardiologist trainees. 3D models of coronary arteries are generated with a fully customizable realistic cardiorespiratory simulator. The transfer of X-ray angiography style to simulator-generated images is performed using a new vessel-specific adaptation of the CycleGAN model. The CycleGAN model is paired with a vesselness-based loss function that is designed as a vessel-specific structural integrity constraint. Validation is performed both on the style and on the preservation of the shape of the arteries of the images. The results show a PSNR of 14.125, an SSIM of 0.898, and an overlapping of 89.5% using the Dice coefficient. We proposed a novel fluoroscopy-based style transfer method for the enhancement of the realism of simulated coronary artery angiograms. The results show that the proposed model is capable of accurately transferring the style of X-ray angiograms to the simulations while keeping the integrity of the structures of interest (i.e., the topology of the coronary arteries).

Analysis of the Whiplash gradient descent dynamics

AbstractIn this paper, we propose the Whiplash inertial gradient dynamics, a closed‐loop optimization method that utilizes gradient information. We introduce the symplectic asymptotic convergence analysis for the Whiplash system for convex functions. We also introduce relaxation sequences to explain the nonclassical nature of the algorithm and an exploring heuristic variant of the Whiplash algorithm to escape saddle points, deterministically. We provide a practical methodology for analyzing convergence rates using integral constraint bounds and a novel Lyapunov rate method. Our results demonstrate polynomial and exponential rates of convergence for quadratic costs.

A consistent projection integration for Galerkin meshfree methods

An efficient and inherently consistent integration method, named projection integration(PI), is proposed for Galerkin meshfree methods with arbitrary order. In contrast to traditional numerical integration methods, PI defines a projection operator based on a weighted norm to systematically approximate meshfree shape functions in an appropriate and consistent function space. Then a substitute function space is established by utilizing projected shape functions as a basis, and Galerkin weak form is approximately calculated by substituting the projected shape functions for the original meshfree shape functions. Owing to the projection consistency of the projection operator, the projected shape functions can still meet consistent conditions. For convenient implementations, the triangular finite element space is selected to approximate meshfree shape functions and the weight function in the weighted norm is carefully chosen to simplify the projection operator in this paper. Arbitrary order integration constraint conditions can be easily met by utilizing the corresponding order triangular finite element shape functions with low order Gauss quadrature rules, which means the optimal convergence rate can be obtained. A series of numerical examples are presented to demonstrate the proposed method’s efficiency and superior convergence performance.

Technical Perspective: When is it safe to run a transactional workload under Read Committed?

A data management platform provides many capabilities to assist the data owner, application coder, or end-user. For example, it should support an expressive query language, schema definition, and sophisticated access control. Another way many platforms add value is through a transaction mechanism, which allows the application programmer to indicate that a stretch of code, including multiple accesses to data, represents a single real-world activity and so all these steps should happen as if a single step, despite really being interleaved with other programs, or perhaps cancelled after partial execution. If the platform perfectly hides interleaving of different activities, the execution is called serializable, and this is a great aid to protecting data quality. Any integrity constraint over the data (whether explicitly declared in schema or not) which is preserved by each transaction running alone, is also valid at the end of any serializable execution of several transactions.

On Game Problems of Controlling Pencil Trajectories under Integral Constraints on the Controls of Players

On Game Problems of Controlling Pencil Trajectories under Integral Constraints on the Controls of Players

$\Pi$-strategy for a differential game of pursuit with integral constraints of a generalized type

The paper investigates a differential game of simple pursuit, when the controls of two opposing players are subject to integral constraints of a generalized type. The generalization of the proposed restriction lies in the fact that it includes previously known restrictions such as integral, geometric, linear, exponential and their mixtures. In general, it includes 25 types of pursuit problems with such different types of constraints. To solve the pursuit problem under such generalized constraints, we propose a parallel pursuit strategy ($\Pi$-strategy for short) and find sufficient conditions for the solvability of this problem. At the end of the article, tables are provided that list each particular type of game, the conditions for its solvability, the resolving function (which determines the corresponding $\Pi$-strategy), and the time of capture.