102,182 research outputs found
Socket Preservation after Tooth Extraction: Particulate Autologous Bone vs. Deproteinized Bovine Bone
No full textBackground: The technique of socket preservation after tooth extraction allows for less volumetric decrease after tooth extraction. The aim of this retrospective study was to evaluate differences between alveolar socket preservation performed with deproteinized bovine bone graft and autologous particulate bone graft taken from the mandibular ramus. Materials and Methods: This retrospective study enrolled a total of 21 consecutive patients. A total of 11 patients underwent socket preservation with deproteinized bovine bone graft and collagen matrix (group A), and 10 patients underwent socket preservation performed with particulate autologous bone taken from the mandibular ramus and collagen matrix (group B). All patients received cone beam computed tomography (CBCT) before socket preservation and after four months. Alveolar bone width (ABW) values and alveolar bone height (ABH) values were measured at the first and second CBCT, and the reduction of the values in the two groups was compared. Statistical analysis was performed using Student’s t-test for independent variables, and p values < 0.05 were considered statistically significant. Results: There were no statistically significant differences between ABW reduction of group A and ABW reduction of group B (t-test value p = 0.28). There were no statistically significant differences between ABH reduction of group A and ABH reduction of group B (t-test value p = 0.10). Conclusions: In this retrospective study, no statistical differences were found between the group that received autologous particulate bone compared to the group that received deproteinized bovine bone in socket preservation
Environmental impact of soil erosion under different cover and management systems
No full textRunoff, soil loss and physical chemical composition of surface soil, runoff water and eroded sediment were measured for three erosive rainstorms of the 1988 Autumn-Winter season, on clay soil slopes (Typic Chromoxeret) under different cover and management systems in a locality of Sicily. Four years reconsolidated natural grass-sod (Avena fatua and Lolium tumulentum), natural grass-sod with implanted forage shrubs (Atriplex halimus) and natural grass-rod afforested with Pine trees (Pinus halepensis), reduced significantly runoff and soil loss in comparison with tilled fallow following four years durum wheat cultivation. While differences in runoff and soil loss between reconsolidated systems were not significant, the higher biomass yield (Stringi et al. 1991) and the better soil cover (Chisci et al. 1991) of the Atriplex system, increased O.M. content of the soil and prevented soil erosion under very intense rainstroms of the semiarid Mediterranean area. The comparison of textural and aggregate grain-size composition of surface soil and sediment confirmed that physico-mechanical composition of sediment detached and transported by over-land flow on clayey soils is better estimated by pseudo-textural grain-size composition of surface soil (Chisci et al. 1989) than from textural composition. Soil loss amounts, and O.M., N and P enrichment ratios, combined in a specifically devised Environmental Impact Index (EI), demonstrated the excellent environmental protection value of reconsolidation of arable soils. However, Pinus system was somewhat less efficient than Atriplex and good natural grass-sod systems. © 1993.24923
A distributed Kalman filter with event-triggered communication and guaranteed stability
No full textThe paper addresses Kalman filtering over a peer-to-peer sensor network with a careful eye towards data transmission scheduling for reduced communication bandwidth and, consequently, enhanced energy efficiency and prolonged network lifetime. A novel consensus Kalman filter algorithm with event-triggered communication is developed by enforcing each node to transmit its local information to the neighbors only when this is considered as particularly significant for estimation purposes, in the sense that it notably deviates from the information that can be predicted from the last transmitted one. Further, it is proved how the filter guarantees stability (mean-square boundedness of the estimation error in each node) under network connectivity and system collective observability. Finally, numerical simulations are provided to demonstrate practical effectiveness of the distributed filter for trading off estimation performance versus transmission rate
Fast Algorithms For Generalized Predictive Control
No full textFast algorithms for generalized predictive control (GPC) are derived by adopting an approach whereby dynamic programming and a polynomial formulation are jointly exploited. They consist of a set of coupled linear polynomial recursions by which the dynamic output feedback GPC law is recursively computed with only O(Nn) computations for an n-th order plant and N-steps prediction horizon
Recursive state bounding by parallelotopes
No full textIn this paper, the problem of recursively estimating the state uncertainty set of a discrete-time linear dynamical system is addressed. A novel approach based on minimum-volume bounding parallelotopes is introduced and an algorithm of polynomial complexity is derived. Simulation results and performance comparisons with ellipsoidal recursive state-bounding algorithms are also given. Copyright (C) 1996 Elsevier Science Ltd
Distributed Kalman filtering with data-driven communication
No full textThe paper deals with distributed Kalman filtering over a peer-to-peer sensor network with focus on a data transmission scheduling strategy aiming at reduced communication bandwidth and, consequently, at enhanced energy efficiency and prolonged network lifetime. A novel distributed Kalman filter algorithm with data-driven communication is devised relying on the idea that each node transmit its local information to the neighbors only when this is deemed to be particularly relevant for estimation purposes, i.e. whenever it significantly deviates from the information predicted from the last transmitted one. An interesting information-theoretic interpretation of the proposed strategy is presented and numerical simulations are provided to demonstrate its practical effectivenes
Fast parallel LQ regulator design for adaptive control
No full textA new fast algorithm for linear quadratic (LQ) control optimization is derived using a partial state formulation and is exploited for the synthesis of long-range predictive controllers. The new algorithm requires O(Nn) computations for an nth-order plant and N-step prediction horizon and is about twice as cheap as existing fast algorithms. Systolic implementation on arrays of O(n) processors is also considered to get an O(N) processing time. Both fast algorithms and systolic implementation can be used to considerably speed up the control design task in adaptive predictive control schemes and thus increase the adaptation bandwidth
- …
