658,920 research outputs found
Defining and assessing the transformational nature of smart city governance: Insights from four European cases
Smart cities are a new approach to urban development based on the extensive use of information and communication technologies and on the promotion of environmental sustainability, economic development and innovation. The article is aimed at discussing whether the adoption of a smart city approach entails the transformation of existing institutional structures and administrative practices. To this end, four cases of European smart cities are analysed: Amsterdam, Barcelona, Turin and Vienna. The article describes their models of governance, investigates the level of transformation that occurred in their governmental structures, outlines the main drawbacks and identifies possible connections with the emergent paradigm of the New Public Governance
Effects of variable resistance on smart structures of cubic reconnaissance satellites in various thermal and frequency shocking conditions
Piezoelectric materials are widely used as smart structures in cubic reconnaissance satellites because of their sensing, actuating, and energy-harvesting abilities. In this study, an analytical model is developed in specific mechanical thermal shocking conditions. A special circuit and apparatus is designed for experimentation on the basis of the inverse piezoelectric effect. An equivalent circuit method is used to establish the relationship between the resistance and peak-to-peak voltage of lead zirconate titanate used as smart materials for cubic reconnaissance satellites. Various frequencies and resistance were applied in different mechanical thermal shocking conditions. Moreover, numerical simulations are conducted in various mechanical loading conditions to determine the accumulative effect. The model provides a novel mechanism to characterize the smart structures in cubic reconnaissance satellites. A rise in temperature increases peak-to-peak voltage; a rise in frequency decreases peak-to-peak voltage; and intensified resistance decreases peak-to-peak voltage. Based on experimentation and simulation, the optimum resistance is predicted for the various frequencies and temperatures. The various conditions may correspond to the different applications of smart structures for cubic reconnaissance satellites. The analytical calculations are in good agreement with experimental and numerical calculations. © 2017, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany
Smart EMI monitoring of thin composite structures
This paper presents a structural health monitoring (SHM) method for in-situ damage detection and localization in carbon fibre reinforced plates (CFRP). The detection is
achieved using the electromechanical impedance (EMI) technique employing piezoelectric transducers as high-frequency modal sensors. Numerical simulations based on the finite element method are carried out so as to simulate more than a hundred damage scenarios. Damage metrics are then used to quantify and detect changes between the electromechanical impedance spectrum of a pristine and damaged structure. The localization process relies on artificial neural networks (ANN) whose inputs are derived from a principal component analysis of the damage metrics. It is shown that the resulting ANN can be used as a tool to predict the in-plane position of a single damage in a laminated composite plate
Dynamic response of structures constructed from smart materials
The dynamic analysis of structures constructed of homogeneous smart materials is greatly simplified by the observation that the eigenfunctions of such structures are identical to those of the same structures constructed entirely of purely elastic materials. The dynamic analysis of such structures is thus reduced to the analysis of the temporal behaviour of the eigenmodes of the structure. The theory is illustrated for both continuous and discrete structures using the generalization of 'positive position feedback' to distributed control
Trends in Smart City Development
This report examines the meanings and practices associated with the term 'smart cities.' Smart city initiatives involve three components: information and communication technologies (ICTs) that generate and aggregate data; analytical tools which convert that data into usable information; and organizational structures that encourage collaboration, innovation, and the application of that information to solve public problems
Reconfiguring smart structures using approximate heteroclinic connections
A new method is investigated to reconfigure smart structures using the technique of polynomial series to approximate a true heteroclinic connection between unstable equilibria in a smart structure model. We explore the use of polynomials of varying order to first approximate the heteroclinic connection between two equal-energy, unstable equilibrium points, and then develop an inverse method to control the dynamics of the system to track the reference polynomial trajectory. It is found that high-order polynomials can provide a good approximation to heteroclinic connections and provide an efficient means of generating such trajectories. The method is used first in a simple smart structure model to illustrate the method and is then extended to a more complex model where the numerical generation of true heteroclinic connections is difficult. It is envisaged that being computationally efficient, the method could form the basis for real-time reconfiguration of smart structures using heteroclinic connections between equal-energy, unstable configurations
Printing of wirelessly rechargeable solid-state supercapacitors for soft, smart contact lenses with continuous operations
Recent advances in smart contact lenses are essential to the realization of medical applications and vision imaging for augmented reality through wireless communication systems. However, previous research on smart contact lenses has been driven by a wired system or wireless power transfer with temporal and spatial restrictions, which can limit their continuous use and require energy storage devices. Also, the rigidity, heat, and large sizes of conventional batteries are not suitable for the soft, smart contact lens. Here, we describe a human pilot trial of a soft, smart contact lens with a wirelessly rechargeable, solid-state supercapacitor for continuous operation. After printing the supercapacitor, all device components (antenna, rectifier, and light-emitting diode) are fully integrated with stretchable structures for this soft lens without obstructing vision. The good reliability against thermal and electromagnetic radiations and the results of the in vivo tests provide the substantial promise of future smart contact lenses
- …
