A Resilient Control Strategy for Cyber-Physical Systems Subject to Denial of Service Attacks: A Leader-Follower Set-Theoretic Approach

Multi-agent systems are usually equipped with open communication infrastructures to improve interactions efficiency, reliability and sustainability. Although technologically cost-effective, this makes them vulnerable to cyber-attacks with potentially catastrophic consequences. To this end, we present a novel control architecture capable to deal with the distributed constrained regulation problem in the presence of time-delay attacks on the agents’ communication infrastructure. The basic idea consists of orchestrating the interconnected cyber-physical system as a leader-follower configuration so that adequate control actions are computed to isolate the attacked unit before it compromises the system operations. Simulations on a multi-area power system confirm that the proposed control scheme can reconfigure the leader-follower structure in response to denial of-service (DoS) attacks.      

Impacts of Hydrological Changes on Annual Runoff Distribution in Seasonally Dry Basins

Runoff is expected to change due to climate and land use change. Because it constitutes a large component of the terrestrial water budget, we need to develop new policies for managing regional water resources. To do so, we must first attribute changes in the natural flow regime to either climate or land use change. In this context, the Budyko’s curve has previously been adopted to separate the impacts of climate and land use change on runoff by using long term hydrological variables. In this study, a framework based on Fu’s equation (which describes Budyko’s curve) is used to separate the impacts of climate and land use change on annual runoff distributions. Specifically, this framework is based on a recently developed method to obtain annual runoff probability density function (pdf) in seasonally dry basins—such as those in Mediterranean regions—from climate statistics and Fu’s equation parameter ω. The effect of climate change is captured through variations in the first order statistics of annual rainfall and potential evapotranspiration, while land use change is represented by changes in Fu’s equation parameter ω. The effects of these two drivers (i.e., climate and land use change) are analyzed by reconstructing the annual runoff pdfs for the current period and for likely future scenarios, based on predictions from global circulation models and urbanization trajectories. The results show that climate change can lead to a strong reduction in mean annual runoff, a shift of the runoff pdf toward lower values, and a decrease in its variance. Concurrent changes in climate and land use almost always result in a reduction in the mean annual runoff, due to the greater impact of climate change on the runoff pdf.

     

Conflict resolution in group decision making: insights from a simulation study

User Modeling and User-Adapted Interaction - An individual’s conflict resolution styles can have a large impact on the decision making process of a group. This impact is affected by a variety...     

Linear SVM-based recognition of elementary juggling movements using correlation dimension of Euler Angles of a single arm

Recognizing the human arm movements has several applications, and it can be performed in a number of ways through the use of one or more sensor devices that the technology offers. This paper aims to exploit the exercises performed by jugglers in order to recognize the arm movements on the basis of the only information on the arm orientation provided by the Euler Angles. The proposed recognizer has two modules, i.e., a feature extractor and a classifier. The former reconstructs the dynamics of the system and estimates three correlation dimensions, each associated with a given Euler Angle. The latter is formed by a Linear Support Vector Machine. Extensive experimentations show the effectiveness of the proposed approach.

     

New wine in old bottles or new bottles for new wine? Product language approaches in design‐intensive industries during technological turmoil

It is widely acknowledged that technological innovation affects the development of product language. Some scholars argue that technological innovation leads companies to develop radically different product language to emphasize novelty; conversely, others note that technological innovation pushes companies to recall previous technology product language in order to increase acceptance of the new technology. This article analyzes the rationale that guides firms to choose these alternative approaches when confronting technological innovations of different magnitude and identifies which of them prevails in a design‐intensive industry. In particular, the study—through an analysis of 678 products in the Italian lighting industry—shows that light‐emitting diode (LED) technology (a discontinuous innovation) involved more product language changes than did compact fluorescent lamp (CFL) technology (a continuous innovation) and that a different use of product materials contributed to this higher number of product language changes. By discussing the reasons behind these findings, this paper extends and better qualifies the literature on the relationship between technological innovation and product design innovation.     

Effect of warm mix asphalt chemical additives on the mechanical performance of asphalt binders

Warm mix asphalt (WMA) has become very popular in asphalt pavement construction because it allows reducing both energy consumptions and carbon emissions. WMA can be obtained by using different types of additives and can be produced, applied, and compacted at temperatures 20–40 °C lower than hot mix asphalt. WMA additives allow reducing the working temperatures without compromising the final performance of the asphalt concrete. Many WMA additives are available on the worldwide market and some of them reduce the viscosity of asphalts binder (organic additives or foam) whereas others do not act on this sense (chemical additives). This study focuses on the effect of chemical additives on the performance of asphalt binders for WMA production. To this purpose, a neat bitumen, a polymer modified bitumen (PMB) and two different chemical additives were selected. All the binders were characterized through conventional tests, DSR, MSCR, FTIR and microscopic analysis. The result clearly showed that the influence of the chemical additives on the neat bitumen is negligible or non-existent. On the contrary, significant changes were observed in the modified bitumen properties. Specifically, chemical additives reduce the viscosity temperature susceptibility of PMBs in the temperature range between 80 and 140 °C, increase the rutting resistance potential and the elastic response of PMBs at high temperatures. Moreover, a morphological inspection supported the modifications observed in the rheological properties of PMBs.     

Modes of inbound knowledge flows: are cooperation and outsourcing really complementary?

This study examines the relationship between breadths of two different modes of external knowledge: R&D outsourcing and cooperation. Building upon transaction costs literature and literature on research partner breadth and R&D outsourcing, we hypothesise an U-inverted relationship between outsourcing breadth and innovation performance and a complementary relationship between R&D outsourcing and R&D cooperation. The model is tested on a large sample based on CIS survey for Spain. The empirical analysis confirms the U-inverted relationship between outsourcing breadth and innovation and also reveals an interesting result: the complementary effect of R&D cooperation varies with the level of R&D outsourcing breadth and it is not confirmed for low and medium levels of R&D outsourcing breadth. The results have important implications for theory on the selection of different modes of inbound open innovation and for managers and their cooperation and outsourcing strategies.     

Trap‐State Suppression and Improved Charge Transport in PbS Quantum Dot Solar Cells with Synergistic Mixed‐Ligand Treatments

The power conversion efficiency of colloidal PbS‐quantum‐dot (QD)‐based solar cells is significantly hampered by lower‐than‐expected open circuit voltage (V_OC). The V_OC deficit is considerably higher in QD‐based solar cells compared to other types of existing solar cells due to in‐gap trap‐induced bulk recombination of photogenerated carriers. Here, this study reports a ligand exchange procedure based on a mixture of zinc iodide and 3‐mercaptopropyonic acid to reduce the V_OC deficit without compromising the high current density. This layer‐by‐layer solid state ligand exchange treatment enhances the photovoltaic performance from 6.62 to 9.92% with a significant improvement in V_OC from 0.58 to 0.66 V. This study further employs optoelectronic characterization, X‐ray photoelectron spectroscopy, and photoluminescence spectroscopy to understand the origin of V_OC improvement. The mixed‐ligand treatment reduces the sub‐bandgap traps and significantly reduces bulk recombination in the devices.     

Bias extension test for pantographic sheets: numerical simulations based on second gradient shear energies

We consider a bi-dimensional sheet consisting of two orthogonal families of inextensible fibres. Using the representation due to Rivlin and Pipkin for admissible placements, i.e. placements preserving the lengths of the inextensible fibres, we numerically simulate a standard bias extension test on the sheet, solving a non-linear constrained optimization problem. Several first and second gradient deformation energy models are considered, depending on the shear angle between the fibres and on its gradient, and the results obtained are compared. The proposed numerical simulations will be helpful in designing a systematic experimental campaign aimed at characterizing the internal energy for physical realizations of the ideal pantographic structure presented in this paper.     

Innovative metamodelling-based process design for manufacturing: an application to Incremental Sheet Forming

The use of metamodelling techniques in process design has become indispensable to perform faster solutions reducing time to market. This approach allows the implementation of decision support tools which are easier to use than the conventional numerical simulations. In this paper, a robust metamodelling technique has been designed and its feasibility has been validated for the crucial problem of localised thinning in sheet metal forming process. The proposed methodology is based on the innovative integration between the Design of Experimental statistical method and the Kriging one. This approach, in fact, allows to analyse contemporary the continuous and categorical factors and, as a consequence, to define a single tool for changing process conditions (i.e., material and product shape). To test the reliability of the mathematical approach, the same was performed for the case study of Incremental Sheet Forming, a process strongly affected by the not homogeneous distribution of the thickness. Taking advantage of this strategy, a wide experimental investigation has been performed to build the base of knowledge of the problem both for the metamodelling design and for the validation of the decision support tool; moreover, the experimental data were utilized to set and validate a numerical model, which was subsequently used to enrich the dataset. The proposed metamodel, suitably modified according to each process peculiarities, can be generally adapted for sheet thickness prediction.