Rotational Mobility Analysis of the 3-RFR Class of Spherical Parallel Robots

none4noSpherical parallel manipulators (SPMs) are used to orient a tool in the space with three degrees of freedom exploiting the strengths of a multi-limb architecture. On the other hand, the performance of parallel kinematics machines (PKMs) is often affected by the occurrence of different kinds of singular configurations. The paper aims at characterizing a class of SPMs for which all singularities come to coincide and a single expression is able to describe all the singular configurations of the machines. The study is focused on a class of SPMs with 3-RFR topology (Revolute-Planar-Revolute pairs for each of the three limbs) addressing the mobility and singularity analysis by means of polynomial decomposition and screw theory. The neatness of the equations that are worked out, expressed in a robust formulation based on rotation invariants, allows a straightforward planning of singularity free tasks and simplifies the synthesis of dexterous machines.openCorinaldi, David; Carbonari, Luca; Palpacelli, Matteo-Claudio; Callegari, MassimoCorinaldi, David; Carbonari, Luca; Palpacelli, Matteo-Claudio; Callegari, Massim

Parallel wrists: singularities and performance indices

available on-line: http://isa.umh.es/vr2/euron07/doc/Raffaele/Spherical%20Wrists%20II.pdf

The REDD+ policy arena in Vietnam: participation of policy actors

Reducing emissions from deforestation and degradation (REDD+) has gained increasing global attention because of its potential to reduce carbon emissions and improve forest governance. Reducing emissions from deforestation and degradation requires successful inclusive decision making and accountability. However, there have been limited empirical studies that examine the effectiveness of the current participatory mechanism used in REDD+. Our research analyzes the participation of policy actors in the development of the REDD+ instrument in Vietnam. We are interested in how the political context and the different interests of actors influence the degree of participation in national REDD+ policy decision making. We explored participation through the analysis of the mechanisms, e.g., how actors involve and participate in decision making, and dynamics of participation, e.g., highly centralized policy event vs. donor led event. The study aims to answer three research questions: (1) Who is involved in national REDD+ policy making and what are their interests in participating in core political events? (2) What level of participation do the different political actors have in core political events? and (3) To what extent do the outcomes, e.g., regulations and strategies, of REDD+ policy events incorporate different preferences of policy actors? Our findings highlighted the dominant role of government agencies in REDD+ policy making, which leaves limited political space for nonstate actors, e.g., NGOs and civil society organizations (CSOs), in Vietnam to exert an influence on the final policy outputs. Even in this highly centralized context, however, we found evidence to suggest that some political space in decision making is given to nonstate actors. Within this space, such actors are able to propose alternative policy options. Ensuring inclusive decision making and accountability in the Vietnam context requires a shift in current governance from traditional top-down approaches to a more participatory form of decision making

Parallel Genetic Algorithms for calibrating Cellular Automata models: Application to lava flows

Cellular Automata are highly nonlinear dynamical systems which are suitable for simulating natural phenomena whose behaviour may be specified in terms of local interactions. The Cellular Automata model SCIARA, developed for the simulation of lava flows, demonstrated to be able to reproduce the behaviour of Etnean events. However, in order to apply the model for the prediction of future scenarios, a thorough calibrating phase is required. This work presents the application of Genetic Algorithms, general-purpose search algorithms inspired to natural selection and genetics, for the parameters optimisation of the modelSCIARA. Difficulties due to the elevated computational time suggested the adoption a Master-Slave Parallel Genetic Algorithm for the calibration of the model with respect to the 2001 Mt. Etna eruption. Results demonstrated the usefulness of the approach, both in terms of computing time and quality of performed simulations

On random flights with non-uniformly distributed directions

This paper deals with a new class of random flights $\underline{\bf X}_d(t),t>0,$ defined in the real space $\mathbb{R}^d, d\geq 2,$ characterized by non-uniform probability distributions on the multidimensional sphere. These random motions differ from similar models appeared in literature which take directions according to the uniform law. The family of angular probability distributions introduced in this paper depends on a parameter $\nu\geq 0$ which gives the level of drift of the motion. Furthermore, we assume that the number of changes of direction performed by the random flight is fixed. The time lengths between two consecutive changes of orientation have joint probability distribution given by a Dirichlet density function. The analysis of $\underline{\bf X}_d(t),t>0,$ is not an easy task, because it involves the calculation of integrals which are not always solvable. Therefore, we analyze the random flight $\underline{\bf X}_m^d(t),t>0,$ obtained as projection onto the lower spaces $\mathbb{R}^m,m<d,$ of the original random motion in $\mathbb{R}^d$. Then we get the probability distribution of $\underline{\bf X}_m^d(t),t>0.$ Although, in its general framework, the analysis of $\underline{\bf X}_d(t),t>0,$ is very complicated, for some values of $\nu$, we can provide some results on the process. Indeed, for $\nu=1$, we obtain the characteristic function of the random flight moving in $\mathbb{R}^d$. Furthermore, by inverting the characteristic function, we are able to give the analytic form (up to some constants) of the probability distribution of $\underline{\bf X}_d(t),t>0.$Comment: 28 pages, 3 figure

Transfer of chemical elements from milk to dairy products

Abstract A pilot study was carried out to evaluate the transfer of As, Cd, Pb, Ni, Cr and Hg from milk to dairy products and to correlate their behavior with that of some components and macro-elements of milk. Due to the low level of these chemical elements in most common commercial products, hard cheese was produced starting from cow's milk spiked with the analytes of interest. Several intermediate and final products coming from cheese making were sampled and analysed for content of fat, dry matter, proteins, macro and oligo-elements. The relationship between spiked elements and milk components was evaluated through both the study of concentration factors and the statistical analysis (Principal Component Analysis and correlation matrix). Except for As and Hg, a clear correlation between spiked elements and milk components was found so a likely bond with proteins, fat and dry matter was demonstrated. As for Pb, for which a legal limit (Maximum Level, ML) is set in the pertinent European regulations, it was found that the link with proteins could lead to an increase of this element concentration different from the mere concentration factor from milk to cheese. Furthermore, it was proven that the stage of ripening affected the variation of Pb concentration so this aspect should be deeply considered in case of setting a ML in cheese or extrapolating a ML from milk to cheese

REDD+ policy networks: exploring actors and power structures in an emerging policy domain

Policy making is often neither rational nor solution-oriented, but driven by negotiations of interests of multiple actors that increasingly tend to take place in policy networks. Such policy networks integrate societal actors beyond the state, which all aim, to different degrees, at influencing ongoing policy processes and outcomes. Reducing Emissions from Deforestation and Forest Degradation (REDD+) can be considered as such an emerging policy domain, in which actors cooperate and conflict in network structures, build coalitions and try to control information and finance flows relevant for REDD+ decision making. This special feature is the result of an extensive comparative research effort to investigate national level REDD+ policy processes and emerging policy networks. This unique collection of seven country cases and a comparative study provides evidence on how power, coalitions, and different interactions among actors in policy networks enable the transformational change required for an effective, efficient, and equitable national REDD+ design. However, as we will see in most of the cases, where the dominant coalitions fail to tackle the drivers of deforestation and forest degradation, they also hinder such major policy reforms required for REDD+. The aim of this editorial serves four purposes: first, we provide an argument about “why” policy network analysis is highly relevant to the study of REDD+ policy processes; second, we explain “how” policy network analysis is used in this special feature to investigate policy processes in this domain; and third, we explore the “so what?” or how a policy network lens helps us understand the political opportunities and challenges for REDD+. Finally, we provide an outlook for the relevance and future research design of policy network analysis when applied to REDD+ and to policy network structures more broadly

The Role of Alpha Oscillations among the Main Neuropsychiatric Disorders in the Adult and Developing Human Brain: Evidence from the Last 10 Years of Research

Alpha oscillations (7–13 Hz) are the dominant rhythm in both the resting and active brain. Accordingly, translational research has provided evidence for the involvement of aberrant alpha activ- ity in the onset of symptomatological features underlying syndromes such as autism, schizophrenia, major depression, and Attention Deficit and Hyperactivity Disorder (ADHD). However, findings on the matter are difficult to reconcile due to the variety of paradigms, analyses, and clinical phenotypes at play, not to mention recent technical and methodological advances in this domain. Herein, we seek to address this issue by reviewing the literature gathered on this topic over the last ten years. For each neuropsychiatric disorder, a dedicated section will be provided, containing a concise account of the current models proposing characteristic alterations of alpha rhythms as a core mechanism to trigger the associated symptomatology, as well as a summary of the most relevant studies and scientific con- tributions issued throughout the last decade. We conclude with some advice and recommendations that might improve future inquiries within this field

The Catania 1669 lava eruptive crisis: simulation of a new possible eruption

SCIARA (Smart Cellular Interactive Automata for modeling the Rheology of Aetnean lava flows, to be read as “shea’rah”), our first two-dimensional Cellular Automata model for the simulation of lava flows, was tested and validated with success on several lava events like the 1986/87 Etnean eruption and the last phase of the 1991/93 Etnean one. Real and simulated events are satisfying within limits to forecast the surface covered by the lava flow. Moreover, improved versions have been adopted in testing other real lava flows of Mount Etna and of Reunion Island (Indian Ocean). The model has been applied with success in the determination of risk zones in the inhabited areas of Nicolosi, Pedara, S. Alfio and Zafferana (Sicily). The main goal of the present work has been the verification of the effects, in volcanic risk terms, in the Etnean area from Nicolosi to Catania, of a eruptive crisis similar to the event that occurred in 1669, as if the episode would happen nowadays. Catania has been severely interested in some major Etnean events in history, the most famous one being, namely, the 1669 eruption, involving 1 km3 of lava during 130 days. The simulation of lava tubes and the usage of different histories within the experiments have been crucial in the determination of a new risk area for Catania. In fact, simulations carried out without the introduction of lava tubes, never involved the city, proving the fact that lava tubes, played a fundamental role in the 1669 Catania lava crisis