112 research outputs found
Detection of possible factors favouring the evolution of migraine without aura into chronic migraine
No full textIn a minority of cases, the natural history of migraine without aura (MO) is characterised over time by its evolution into a form of chronic migraine (CM). In order to detect the possible factors predicting this negative evolution of MO, we searched in our Headache Centre files for all clinical records that met the following criteria: (a) first visit between 1976 and 1998; (b) diagnosis of MO or of common migraine at the first observation, with or without association with other primary headache types; (c) <15 days per month of migraine at the first observation; and (d) at least one follow-up visit at least 10 years after the first visit. The patients thus identified were then divided into two groups based on a favourable/steady evolution (Group A: n = 243, 195 women and 48 men) or an unfavourable evolution (Group B: n = 72, 62 women and 10 men) of their migraine over time. In the two groups, we compared various clinical parameters that were present at the first observation or emerged at the subsequent follow-up visits. The parameters that were statistically significantly more frequent in Group B--and can therefore be considered possible negative prognostic factors--were: (a) ≥ 10 days per month of migraine at the first observation; (b) presence of depression at the first visit in males; and (c) onset of depression or arterial hypertension after the first observation but before transformation to CM in females. Based on these findings, in MO patients the high frequency of migraine attacks, comorbidity with depression, and the tendency to develop arterial hypertension should require particular attention and careful management to prevent evolution into CM
Advanced probabilistic load flow methodology for voltage unbalance assessment in PV penetrated distribution grids
No full textThe balancing of three-phase node voltages in modern power distribution grids can be significantly deteriorated by the penetration of single-phase PV renewable sources. For a given grid topology and prescribed loads, voltage unbalance critically depends on the nodes where power is injected. Its amount can vary substantially at different observations Buses in the grid. In this paper, we present a methodology that can inform network operators about the critical Buses in the grid and critical injection scenarios. The method is based on a numerically efficient but accurate probabilistic load flow that can handle the case of many PV sources and provides detailed information on the probability distribution of voltage unbalance. The proposed methodology relies on the complex-domain modeling of voltage unbalance sensitivity and on accelerating Monte Carlo simulations via parameter space partitioning
A parameter optimization approach to the computer-aided design of structurally constrained multivariable regulators
No full textA dexterous gripper for space robotics
No full textThe paper summarises the work done so far by four University groups involved in a joint project for the development of a medium-complexity robotic gripper, respectively developing the mechanical design (DIEM Bologna), the sensory and control system (DEIS-Bologna), the dynamic simulation (DEI-Milano) and the sensor fusion (DII-Parma). The gripper has been deigned in order to perform low- and medium-complexity space-lab manipulation tasks, aiming to achieve a trade-off between simple twin-jawed grippers and highly sophisticated multidegree-of-freedom hands. It presents a three-finger, three- degree-of-freedom architecture and is capable of synchronous application of the grasping contacts, so that force-closure grasps can be achieved on irregularly shaped objects even floating in micro-gravity conditions. Proximity sensors and intrinsic contact force sensors installed on each finger can allow object shape recognition together with control of approaching and grasping procedures. The capability of being tele-operated is addressed as well as the possibility of accomplishing elementary tasks in autonomous way
Minimizing production costs in generation and cogeneration plants
No full textTechnological advances, the shift towards deregulation and anti-pollution regulation are bringing dramatic changes in the power generation field. Power and heat are increasingly perceived as products to be sold and bought on the basis of cost/profit considerations in a fast changing market. This requires a substantial effort in the field of economic optimisation of plant management, since solutions based on conventional wisdom or past practice are no longer adequate. Due to the complexity of the factors involved, model-based decision support systems are needed for this task. These issues are discussed with reference to two radically different but equally representative examples
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