Lecture notes in electrical engineering, Nov 3, 2017
A mathematical model for the output signal’s energy of a multidimensional ideal DAC is presented ... more A mathematical model for the output signal’s energy of a multidimensional ideal DAC is presented considering sampling clock jitter. More specifically, a new model is formulated to prove one-sided energy inequality for the output signal, for which the base time is affected by the jitter. Moreover, a family of annihilate operators is defined and applied to the ideal (one-dimensional) DAC model to estimate the output signal energy.
The liberalization of the Italian electricity market has led to a situation where the logic of ma... more The liberalization of the Italian electricity market has led to a situation where the logic of maximizing operators’ profits prevails. In this context, it is essential for electricity producers to be able to formulate supply strategies. Therefore, plants that can buy or store the energy resources they use to produce electricity are advantaged, because they can choose when to produce with more flexibility. This feature is often absent in environmentally sustainable electrical plants, although hydropower storage plants offer flexibility to the electricity system and allow their operators to formulate bidding strategies. This paper provides a method to identify the best predictive variables and the appropriate predictive indexes for an aggregate hydropower storage forecasting model. To this end, we use an entropy-based approach. The optimal subset can be considered complete, meaning it incorporates both market and physical variables, including those influencing the timing of snowpack melting. In particular, we show that the variables that incorporate the expectations of the operators always have a more dominant role than the realized variables in understanding the current hydropower generation. We find evidence of a cyclicality, over the year, of relevant drivers in the representative subset; in particular, we show the mechanism by which, during this cycle, some variables become more or less influential on others.
PurposeThough the circular economy (CE) is a current buzzword, this still lacks a precise definit... more PurposeThough the circular economy (CE) is a current buzzword, this still lacks a precise definition. In the absence of a clear notion of what that term includes, actions taken by the government and companies may not be well informed. In particular, those actions need to consider what people mean when people talk about the CE, either to refocus people's decisions or to undertake a more effective communications strategy.Design/methodology/approachSince people voice people's opinions mainly through social media nowadays, special attention has to be paid to discussions on those media. In this paper, the authors focus on Twitter as a popular social platform to deliver one's thoughts quickly and fast. The authors' research aim is to get the perceptions of people about the CE. After collecting more than 100,000 tweets over 16 weeks, the authors analyse those tweets to understand the public discussion about the CE. The authors conduct a frequency analysis of the most recurr...
The aim of this work is to investigate the different implications in terms of political stability... more The aim of this work is to investigate the different implications in terms of political stability that a high oil dependency has in both oil-exporting and oil-importing countries. We employ network analysis to understand which countries are most connected in the global crude oil trade, and central in the intermediation of the flows. Then, we use this information to estimate the effects of oil dependency on political stability on a panel of 155 countries over the period 1995-2019, by means of a simultaneous-quantile regression model. Our findings corroborate the resource curse hypothesis in relation to oil-exporting countries, especially linking this outcome to the emergence of rent-seeking behaviours. Interestingly, we find that a different type of resource curse hypothesisrelated to the indirect endowment of oil resourcesalso affects intermediary countries. As for oil importers, we find that countries that are heavily dependent on oil as the main energy source are largely exposed to geopolitical turmoil and risk to import political instability together with oil.
As pointed out by many researchers, replication plays a key role in the credibility of applied sc... more As pointed out by many researchers, replication plays a key role in the credibility of applied sciences and the confidence in all research findings. With regard, in particular, to energy finance and economics, replication papers are rare, probably because they are hampered by inaccessible data, but their aim is crucial. We consider two ways to avoid misleading results on the ostensible chaoticity of price series. The first one is represented by the proper mathematical definition of chaos and the related theoretical background, while the latter is represented by the hybrid approach that we propose here—i.e., consisting of considering the dynamical system underlying the price time series as a deterministic system with noise. We find that both chaotic and stochastic features coexist in the energy commodity markets, although the misuse of some tests in the established practice in the literature may say otherwise.
A mathematical model for the output signal’s energy of a multidimensional ideal DAC is presented ... more A mathematical model for the output signal’s energy of a multidimensional ideal DAC is presented considering sampling clock jitter. More specifically, a new model is formulated to prove one-sided energy inequality for the output signal, for which the base time is affected by the jitter. Moreover, a family of annihilate operators is defined and applied to the ideal (one-dimensional) DAC model to estimate the output signal energy.
Nonlinear Dynamics of Structures, Systems and Devices, 2020
We summarize some recent results concerning the study of the asymptotic properties of four import... more We summarize some recent results concerning the study of the asymptotic properties of four important enzyme reactions, which are ubiquitous in every intracellular enzyme reaction network. Mainly following the fundamental ideas by Nayfeh, after ad hoc adimensionalizations, we apply classical singular perturbation techniques in order to determine the matched expansions of the solutions, in terms of a suitable parameter, up to the first order. We show some numerical results, for the different mechanisms and different parameter values.
In a group of individuals aiming for a collective decision, that decision is influenced by indivi... more In a group of individuals aiming for a collective decision, that decision is influenced by individual competences, but these are in turn subject to a reciprocal influence. Such an influence may lead to less competent agents exerting an unduly influence, a phenomenon known as equality bias. In this paper an agent-based model is proposed to investigate the evolution of competences under such a reciprocal influence. Through MonteCarlo simulation it is shown that: a) the average competence at steady state diminishes as the degree of interaction among the agents and/or the number of agents grow, both in the case of just positive influence (more competent agents increasing the competence of less competent one) and when both positive and negative influences are present; b) the convergence towards a steady state value is slow and characterized by oscillations.
We introduce a control model for an octopus robot tentacle. The model extends to a continuous set... more We introduce a control model for an octopus robot tentacle. The model extends to a continuous setting a class of hyper-redundant planar manipulators characterized by a self-similar structure. The proposed model encompasses manipulators with a links scaling according to Fibonacci sequence. We characterize the class of continuous functions whose graph can be reparametrized as a configuration of the system and we provide an explicit control law. In particular, we give the conditions to prescribe an admissible path for the configurations of the manipulator. The result is an attempt to determine an entire class of admissible paths for the arm deformations.
In this paper we apply some results obtained for "perturbed" Whittaker's cardinal s... more In this paper we apply some results obtained for "perturbed" Whittaker's cardinal series, $\sum_{k\in\mathbb Z} a_k \operatorname{sinc}(t-\lambda_k)$, to problem of signal reconstruction in a Digital Audio Processes, where we consider ideal bandlimited interpolation and the variability of $\{\lambda_k\}_{k\in\mathbb Z}$ models sampling clock jitter effects. Results applied in this work concern a stability theorem, by previous work, and a generalization of the Parseval's identity for perturbed Whittaker's cardinal series, here introduced for the first time.
In previous papers we introduced a class of polynomials which follow the same recursive formula a... more In previous papers we introduced a class of polynomials which follow the same recursive formula as the Lucas-Lehmer numbers, studying the distribution of their zeros and remarking that this distribution follows a sequence related to the binary Gray code. It allowed us to give an order for all the zeros of every polynomial $L_n$. In this paper, the zeros, expressed in terms of nested radicals, are used to obtain two new formulas for $\pi$: the first can be seen as a generalization of the known formula $$\pi=\lim_{n\rightarrow \infty} 2^{n+1}\cdot \sqrt{2-\underbrace{\sqrt{2+\sqrt{2+\sqrt{2+...+\sqrt{2}}}}}_{n}} \ ,$$ related to the smallest positive zero of $L_n$; the second is an exact formula for $\pi$ achieved thanks to some identities of $L_n$. We also introduce two relationships between $\pi$ and the golden ratio $\varphi$.
Lecture notes in electrical engineering, Nov 3, 2017
A mathematical model for the output signal’s energy of a multidimensional ideal DAC is presented ... more A mathematical model for the output signal’s energy of a multidimensional ideal DAC is presented considering sampling clock jitter. More specifically, a new model is formulated to prove one-sided energy inequality for the output signal, for which the base time is affected by the jitter. Moreover, a family of annihilate operators is defined and applied to the ideal (one-dimensional) DAC model to estimate the output signal energy.
The liberalization of the Italian electricity market has led to a situation where the logic of ma... more The liberalization of the Italian electricity market has led to a situation where the logic of maximizing operators’ profits prevails. In this context, it is essential for electricity producers to be able to formulate supply strategies. Therefore, plants that can buy or store the energy resources they use to produce electricity are advantaged, because they can choose when to produce with more flexibility. This feature is often absent in environmentally sustainable electrical plants, although hydropower storage plants offer flexibility to the electricity system and allow their operators to formulate bidding strategies. This paper provides a method to identify the best predictive variables and the appropriate predictive indexes for an aggregate hydropower storage forecasting model. To this end, we use an entropy-based approach. The optimal subset can be considered complete, meaning it incorporates both market and physical variables, including those influencing the timing of snowpack melting. In particular, we show that the variables that incorporate the expectations of the operators always have a more dominant role than the realized variables in understanding the current hydropower generation. We find evidence of a cyclicality, over the year, of relevant drivers in the representative subset; in particular, we show the mechanism by which, during this cycle, some variables become more or less influential on others.
PurposeThough the circular economy (CE) is a current buzzword, this still lacks a precise definit... more PurposeThough the circular economy (CE) is a current buzzword, this still lacks a precise definition. In the absence of a clear notion of what that term includes, actions taken by the government and companies may not be well informed. In particular, those actions need to consider what people mean when people talk about the CE, either to refocus people's decisions or to undertake a more effective communications strategy.Design/methodology/approachSince people voice people's opinions mainly through social media nowadays, special attention has to be paid to discussions on those media. In this paper, the authors focus on Twitter as a popular social platform to deliver one's thoughts quickly and fast. The authors' research aim is to get the perceptions of people about the CE. After collecting more than 100,000 tweets over 16 weeks, the authors analyse those tweets to understand the public discussion about the CE. The authors conduct a frequency analysis of the most recurr...
The aim of this work is to investigate the different implications in terms of political stability... more The aim of this work is to investigate the different implications in terms of political stability that a high oil dependency has in both oil-exporting and oil-importing countries. We employ network analysis to understand which countries are most connected in the global crude oil trade, and central in the intermediation of the flows. Then, we use this information to estimate the effects of oil dependency on political stability on a panel of 155 countries over the period 1995-2019, by means of a simultaneous-quantile regression model. Our findings corroborate the resource curse hypothesis in relation to oil-exporting countries, especially linking this outcome to the emergence of rent-seeking behaviours. Interestingly, we find that a different type of resource curse hypothesisrelated to the indirect endowment of oil resourcesalso affects intermediary countries. As for oil importers, we find that countries that are heavily dependent on oil as the main energy source are largely exposed to geopolitical turmoil and risk to import political instability together with oil.
As pointed out by many researchers, replication plays a key role in the credibility of applied sc... more As pointed out by many researchers, replication plays a key role in the credibility of applied sciences and the confidence in all research findings. With regard, in particular, to energy finance and economics, replication papers are rare, probably because they are hampered by inaccessible data, but their aim is crucial. We consider two ways to avoid misleading results on the ostensible chaoticity of price series. The first one is represented by the proper mathematical definition of chaos and the related theoretical background, while the latter is represented by the hybrid approach that we propose here—i.e., consisting of considering the dynamical system underlying the price time series as a deterministic system with noise. We find that both chaotic and stochastic features coexist in the energy commodity markets, although the misuse of some tests in the established practice in the literature may say otherwise.
A mathematical model for the output signal’s energy of a multidimensional ideal DAC is presented ... more A mathematical model for the output signal’s energy of a multidimensional ideal DAC is presented considering sampling clock jitter. More specifically, a new model is formulated to prove one-sided energy inequality for the output signal, for which the base time is affected by the jitter. Moreover, a family of annihilate operators is defined and applied to the ideal (one-dimensional) DAC model to estimate the output signal energy.
Nonlinear Dynamics of Structures, Systems and Devices, 2020
We summarize some recent results concerning the study of the asymptotic properties of four import... more We summarize some recent results concerning the study of the asymptotic properties of four important enzyme reactions, which are ubiquitous in every intracellular enzyme reaction network. Mainly following the fundamental ideas by Nayfeh, after ad hoc adimensionalizations, we apply classical singular perturbation techniques in order to determine the matched expansions of the solutions, in terms of a suitable parameter, up to the first order. We show some numerical results, for the different mechanisms and different parameter values.
In a group of individuals aiming for a collective decision, that decision is influenced by indivi... more In a group of individuals aiming for a collective decision, that decision is influenced by individual competences, but these are in turn subject to a reciprocal influence. Such an influence may lead to less competent agents exerting an unduly influence, a phenomenon known as equality bias. In this paper an agent-based model is proposed to investigate the evolution of competences under such a reciprocal influence. Through MonteCarlo simulation it is shown that: a) the average competence at steady state diminishes as the degree of interaction among the agents and/or the number of agents grow, both in the case of just positive influence (more competent agents increasing the competence of less competent one) and when both positive and negative influences are present; b) the convergence towards a steady state value is slow and characterized by oscillations.
We introduce a control model for an octopus robot tentacle. The model extends to a continuous set... more We introduce a control model for an octopus robot tentacle. The model extends to a continuous setting a class of hyper-redundant planar manipulators characterized by a self-similar structure. The proposed model encompasses manipulators with a links scaling according to Fibonacci sequence. We characterize the class of continuous functions whose graph can be reparametrized as a configuration of the system and we provide an explicit control law. In particular, we give the conditions to prescribe an admissible path for the configurations of the manipulator. The result is an attempt to determine an entire class of admissible paths for the arm deformations.
In this paper we apply some results obtained for "perturbed" Whittaker's cardinal s... more In this paper we apply some results obtained for "perturbed" Whittaker's cardinal series, $\sum_{k\in\mathbb Z} a_k \operatorname{sinc}(t-\lambda_k)$, to problem of signal reconstruction in a Digital Audio Processes, where we consider ideal bandlimited interpolation and the variability of $\{\lambda_k\}_{k\in\mathbb Z}$ models sampling clock jitter effects. Results applied in this work concern a stability theorem, by previous work, and a generalization of the Parseval's identity for perturbed Whittaker's cardinal series, here introduced for the first time.
In previous papers we introduced a class of polynomials which follow the same recursive formula a... more In previous papers we introduced a class of polynomials which follow the same recursive formula as the Lucas-Lehmer numbers, studying the distribution of their zeros and remarking that this distribution follows a sequence related to the binary Gray code. It allowed us to give an order for all the zeros of every polynomial $L_n$. In this paper, the zeros, expressed in terms of nested radicals, are used to obtain two new formulas for $\pi$: the first can be seen as a generalization of the known formula $$\pi=\lim_{n\rightarrow \infty} 2^{n+1}\cdot \sqrt{2-\underbrace{\sqrt{2+\sqrt{2+\sqrt{2+...+\sqrt{2}}}}}_{n}} \ ,$$ related to the smallest positive zero of $L_n$; the second is an exact formula for $\pi$ achieved thanks to some identities of $L_n$. We also introduce two relationships between $\pi$ and the golden ratio $\varphi$.
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