http://http://dspace.unitus.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. 2013-05-25T18:55:55Z http://hdl.handle.net/2067/1113 Title: Trasformazione del materiale ligno-cellulosico proveniente dal bosco in biocombustibili solidi: aspetti tecnico - economici di un impianto per la produzione di pellet e cippato Authors: Guerrieri, Mirko Abstract: Questo lavoro è il risultato di un’analisi tecnico economica del processo di trasformazione della biomassa legnosa in biocombustibili solidi, pellet e cippato. Il processo di trasformazione della biomassa legnosa inizia con la fase di triturazione realizzata mediante una macchina cippatrice che riduce il materiale dalla forma solida compatta ad uno stato disgregato (chips). Il prodotto viene quindi vagliato in modo da separare la parte sottile da quella più grossolana e poi insaccato. Per la produzione di pellet invece il processo è più articolato perché bisogna raffinare ulteriormente il composto creando una polvere di legno che viene subito pressata in modo da realizzare la classica forma cilindrica del pellet. La studio della produttività delle singole macchine è avvenuto analizzando le schede compilate giornalmente dai tecnici dell’impianto e nel quale vengono riportate informazioni relative alle quantità di materiale lavorato nell’ unità di tempo. La valutazione economica è stata realizzata con procedimento analitico considerando il costo orario della manodopera e delle singole macchine impiegate in tutte le fasi di lavoro. Per quest’ ultima analisi sono state prese in considerazione più metodologie proposte in letteratura da vari autori ma integrate, soprattutto per quanto riguarda parametri e coefficienti tecnici, con informazioni derivanti dagli operatori che lavorano con le macchine stesse. È stato quindi determinato il costo di produzione reale di ogni prodotto finito ed infine sono state suggerite delle proposte finalizzate al miglioramento di tutto il processo di trasformazione in modo da raggiungere la conseguente riduzione dei costi produttivi.; This work is the result of a technical and economic analysis about the process of transformation of forest wood in biofuels, pellets and wood chips. The first phase of forest biomass transformation is the chipping, which is realized through a woodchipper that reduces wood into smaller parts, such as wood chips or sawdust. Thus, the product is sifted to separate the thin part from the coarser one, and then is bagged. The production process of woodpellet is more articulated: it is necessary to refine the mixture a bit more, creating a wood dust which is immediately compressed to form the classical cylindrical pellet’s shape and to provide a uniform dough-like mass. The study of the productivity of machinery employed in the transformation of the wood material was made analyzing the cards compiled daily from the technicians of the pilot plant. In these cards information about the amount of material worked in the unit time was recorded. The economic evaluation has been completed following an analytical procedure considering the hourly manpower cost and the single machines utilized in all the process phases. In order to carry out this last analysis, various methodologies found in literature have been considered and integrated with the information coming directly from machine operators. The last part of the study concerns the evaluation of the real cost of production for every output and gives some suggestions to improve the whole process of transformation and consequently to reduce production costs. Description: Dottorato di ricerca in Meccanica agraria 2009-02-22T23:00:00Z http://hdl.handle.net/2067/1810 Title: Evaluation of respirable dust exposure during hazelnut and chestnut mechanized harvesting. Authors: Monarca, Danilo; Biondi, Paolo; Cecchini, Massimo; Santi, Massimo; Guerrieri, Mirko; Colantoni, Andrea Abstract: Atmospheric dust is defined in different ways but the most used classification are “total suspended dust” (T.S.D) and “particulate matter” (P.M.). A further distinction within the T.S.D. is about inhalable and respirable dust. Inhalable dust has an aerodynamic diameter between 5 and 10 m, while respirable dust presents a diameter between 0,5 and 5 m. Beside the dimension, the danger about dust regards other factors, like: concentration, chemical composition, individual absorption characteristics and exposure time. The mechanized harvesting of nuts, like hazelnuts and chestnuts, is carried out with specific machines that can be classified in three different types: pulled vacuum harvesters with aspirating tubes; pulled or tractor mounted harvesters with automatic picking system; self-propelled harvesters (aspirating or picking). In spite of installation of dust limitation devices, some studies have shown that dust concentration is still more elevated (up to 10 times) than the maximum limits indicated by the American Conference of Governmental Industrial Hygienists (A.C.G.I.H.). The objective of the present study is to evaluate the level of risk at which operators, during nut mechanized harvesting and using modern machines, are really exposed. In order to carry out this survey the data have been collected among some farms of the province of Viterbo (Italy); the farms selected have heterogeneous characteristics so that it is possible to obtain representative results for each type of working site and ground. 2007-12-31T23:00:00Z http://hdl.handle.net/2067/1811 Title: Transmission of vibrations from portable agricultural machinery to the hand-arm system (HAV): risk evaluation and definition of exposure time for daily action and exposure limits. Authors: Monarca, Danilo; Biondi, Paolo; Cecchini, Massimo; Santi, Massimo; Guerrieri, Mirko; Colantoni, Andrea; Colopardi, Francesco Abstract: Every day agro-forestry workers are exposed to health and safety risks, due to work environment and the machineries they use. Some of these risks, vibrations for example, are usually underestimated by workers as well, because vibrations do not represent an immediate risk for the health. The vibrations can cause some professional diseases whose symptoms can appear after many years too. This is not a good reason to ignore the problem; in fact the consequences of a long exposure time can be very serious. A deeper knowledge of diseases caused by vibrations, laws, the best precautions and safety systems can represent a start to limit the phenomenon. The research about agro-forestry machineries can represent a stimulus to use ergonomic instruments in order to guarantee the health and the safety of the workers. The present research aims to highlight the importance of the exposure to vibrations in agro-forestry sector and its consequences on human health, above all the risks for the hand-arm system during the working day. Every machine has been directly analyzed to establish the level of vibrations produced according to the laws in force and the most recent ISO norms. With the collected data it was possible to establish the maximum exposure times for every instrument in order to respect the European Directive 2002/44/CE of 25 June 2002 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (vibrations). 2007-12-31T23:00:00Z http://hdl.handle.net/2067/1812 Title: Exposure to hand-arm and whole-body vibrations for workers employed to blowers Authors: Monarca, Danilo; Cecchini, Massimo; Guerrieri, Mirko; Colantoni, Andrea; Colopardi, Francesco Abstract: Six portable blowers were chosen in order to evaluate the potential risks to operators through their exposure to hand-arm and whole body vibrations. These evaluations are based on internationally standars, with particular reference to Italian legislation of August 19th, 2005, nr 187 (directive 2002/44/EC), which lays down specific measures regarding exposure to mechanical vibration and its affect on health and measures regarding exposure to mechanical vibration and its affect on health and safety. All the levels of accelerations normalized to 8 hours have been measured and referred to a 7 hours daily period of exposure, and all results checked against the exposure limit values. 2006-12-31T23:00:00Z