Control and virtual reality simulation of tendon driven mechanisms

In this paper the authors present a control strategy for tendon driven mechanisms. The aim of the control system is to find the correct torques which the motors have to exert to make the end effector describe a specific trajectory. In robotic assemblies this problem is often solved with closed loop algorithm, but here a simpler method, based on a open loop strategy, is developed. The difficulties in the actuation are in keeping the belt tight during all working conditions. So an innovative solution of this problem is presented here. This methodology can be easily applied in real time monitoring or very fast operations. For this reason several virtual reality simulations, developed using codes written in Virtual Reality Markup Language, are also presented. This approach is very efficient because it requires a very low cpu computation time, small size files, and the manipulator can be easily put into different simulated scenarios

Approccio alla caratterizzazione di un lembo di bosco vetusto: il caso di Monte Egitto

An integrated approach to characterize an old growth forest patch; the Monte Egitto case study Old growth forests, i.e. forests which have achieved a remarkable age without or with a very limited disturbance, are nowadays subject of detailed studies in order to understand their characters and capacity of ecosystems services providing. In Sicily only few wooded areas are classified as old growth forest, following the heavy land use change toward agriculture during the centuries. This paper reports the results of a study carried out to characterize the vegetation of a little crater on the Mount Etna, where a residual open wood of Quercus congesta (an endemic oak of Southern Italy) survived the year 1651 lava flows surrounding the crater. About 35 years ago inside the crater some areas were planted with Calabrian Black Pine. As a consequence today there is a remarkable competition between trees of the two species. An integrated approach monitoring was adopted, taking into account both trees and understory (herbs, shrubs and tree regeneration) characters as well as bird fauna, in order to describe the current situation and monitor the effect of pine plantation thinning aimed at favouring oak regeneration and reducing pine-oak competition

Orientation dependent molecular electrostatics drives efficient charge generation in homojunction organic solar cells

Organic solar cells usually utilise a heterojunction between electron-donating (D) and electron-accepting (A) materials to split excitons into charges. However, the use of D-A blends intrinsically limits the photovoltage and introduces morphological instability. Here, we demonstrate that polycrystalline films of chemically identical molecules offer a promising alternative and show that photoexcitation of α-sexithiophene (α-6T) films results in efficient charge generation. This leads to α-6T based homojunction organic solar cells with an external quantum efficiency reaching up to 44% and an open-circuit voltage of 1.61 V. Morphological, photoemission, and modelling studies show that boundaries between α-6T crystalline domains with different orientations generate an electrostatic landscape with an interfacial energy offset of 0.4 eV, which promotes the formation of hybridised exciton/charge-transfer states at the interface, dissociating efficiently into free charges. Our findings open new avenues for organic solar cell design where material energetics are tuned through molecular electrostatic engineering and mesoscale structural control

Family climate in children living with parents who harmfully consume alcohol

The family climate has notable impact on cognitive, emotional, behavioural, social and physical development of children and adolescents and can be influenced by parents' health status. The present study aimed at evaluating whether living with a parent with alcohol use disorder negatively influences the perceived emotional family climate, parental attitudes and internal representations of family relationships. Forty-five children living with a parent with alcohol use disorder and 45 controls, matched for sex and age, completed the Level of Expressed Emotion Scale and the Family Attitudes Questionnaire. Their significant parent completed the Parental Attitudes Scale. The results suggested that living with a parent with an alcohol use disorder increased the risk of having perceived higher levels of emotional response, attitude towards illness and expectations from their parents; it also increased the probability of being exposed to lower parental pleasure and of having represented worse family relationships. Emotion regulation interventions might be useful to protect children living with a parent with alcohol use disorder from a potential chaotic and unpredictable family environment

DETC2003/VIB-48335 A METHOD TO INVESTIGATE VIBRATIONS IN TENDON DRIVEN MECHANISMS

In this paper the authors develop a mechanical model to analyze the vibrational behavior of tendon driven mechanisms. The description of kinematics makes use of the correspondence between graphs and mechanisms, based on the works of L.W. Tsai and J.J. Lee [1-4], and on Denavit-Hartenberg approach to study serial manipulators [5,6]. The equations of dynamics for a generic n-link manipulator have been deduced by Londi [8] by means of a Lagrangian approach in case of rigid belts. These equations have been modified to take into account belt elasticity, according to the Hooke’s law. The correct value of belt tension is computed using the λ-corrector algorithm developed by the authors [9]. A numerical example concerning a three degree-of-freedom manipulator is also presented

Programmare la selvicoltura in un bosco vetusto all\u2019interno di un cratere secondario del Monte Etna: primi risultati

In questo contributo sono presentati i primi risultati di uno studio multidisciplinare condoto su un lembo di bosco vetusto a quercia congesta (Qercus congesta C. Presl) all\u2019interno di un cratere secondario sulle pendici del cono vulcanico del Monte Etna, il cratere di Monte Egito. L\u2019obietivo generale \ue8 migliorare l\u2019eficienza ecosistemica di queste formazioni riconosciute come habitat di interesse comunitario (91AA* - boschi orientali di quercia bianca) tramite una selvicoltura eficiente ed eficace, programmata ed adatata sulla base delle carateristiche peculiari dell\u2019ecosistema forestale, valutandone nel tempo i risultati dopo l\u2019esecuzione degli interventi programmati. \uc8 stato adotato un approccio multidisciplinare che ha previsto il campionamento e il monitoraggio ripetuto di alcuni indicatori ecologici dell\u2019habitat forestale di Monte Egito: (i) la ricchezza floristica e la mappatura del mosaico delle coperture e della vegetazione; (ii) la caraterizzazione dendrometrico-struturale del soprassuolo arboreo; (iii) il rilievo degli aspeti compositivi, distributivi e dimensionali della rinnovazione delle specie legnose; (iv) il rilievo della necromassa in piedi e a terra; (v) il rilievo ornitologico. L\u2019insieme di queste informazioni costituir\ue0 un sistema di supporto utile alla pianificazione di una gestione forestale funzionale al mantenimento di questo habitat

Family climate, expressed emotion, and parental attitudes in families of alcoholics

Introduction: parental alcoholism may lead to adverse psychological outcomes for those who grow up in such family environments. Objectives: several studies show that children of alcoholics (COAs) live in family climates characterized by conflict, unpredictability, and manifestations of contempt. Moreover, COAs are exposed to a high level of expressed emotion due, for instance, to threats and denigration. Aims: we compared a group of COAs with a group of non COAs measuring the family climate, the level of expressed emotion and the parental attitudes on the basis of both children and parents’ point of view. Methods: 25 COAs (mean age 17,8 ± 3,3 years) and 25 non COAs (mean age 18,3 ± 3,3 years), matched for age and sex, were evaluated in the frame of an observational naturalistic study design. Self-administered rating scales were used to assess the level of expressed emotion in the family (Level of Expressed Emotion Scale - LEES), the parental (Parental Attitudes Scales - PAD) and family (Family Attitudes Questionnaire - FAQ) attitudes. Results: The two groups did differ for FAQ total score and for the FAQ subscale assessing the relation between parents. They also differed for the level of expressed emotion (i.e., LEES total score) and for the LEES subscale assessing tolerance and expectations. Conclusions: COAs are characterized by the perception of a negative family climate that is primarily expressed in terms of conflict and deterioration of relationship between parents

Impact of Triplet Excited States on the Open‐Circuit Voltage of Organic Solar Cells

The best organic solar cells (OSCs) achieve comparable peak external quantum efficiencies and fill factors as conventional photovoltaic devices. However, their voltage losses are much higher, in particular those due to nonradiative recombination. To investigate the possible role of triplet states on the donor or acceptor materials in this process, model systems comprising Zn‐ and Cu‐phthalocyanine (Pc), as well as fluorinated versions of these donors, combined with C60 as acceptor are studied. Fluorination allows tuning the energy level alignment between the lowest energy triplet state (T1) and the charge‐transfer (CT) state, while the replacement of Zn by Cu as the central metal in the Pcs leads to a largely enhanced spin–orbit coupling. Only in the latter case, a substantial influence of the triplet state on the nonradiative voltage losses is observed. In contrast, it is found that for a large series of typical OSC materials, the relative energy level alignment between T1 and the CT state does not substantially affect nonradiative voltage losses

Kinematic Synthesis of a Tendon-Driven Robotic Arm

This paper deals with the kinematic synthesis of a planar tendon-driven robotic arm to remove skins by wine fermentation tanks, with three d.o.f.s and thus, one time redundant. This redundancy is required in order to obtain a deployable mechanism in the form of robotic arm, which shows a wide workspace, but occupies a small volume when fully flexed. The type and dimensional kinematic synthesis of the proposed robotic arm is developed through a serial combination of endless tendon-driven kinematic chains, which joints are remotely actuated. The synthesis methodology is first applied to a Cardan mechanism, a parallel motion generator, a robotic finger, and then, to the synthesis of the proposed robotic arm with the aim to satisfy the design specifications