Evaluation of spatial distribution of flatfish by laser scannig

Peer reviewed

Determinação do volume de madeira em povoamento de eucalipto por escâner a laser aerotransportado

O objetivo deste trabalho foi avaliar a possibilidade de se estimar o diâmetro à altura do peito (DAP) com os dados de altura e de número de árvores derivados do escâner a laser aerotransportado (LiDAR, "light detection and ranging"), e determinar o volume de madeira de talhão de Eucalyptus sp. a partir dessas variáveis. O número total de árvores detectadas foi obtido com uso da filtragem de máxima local. A altura de plantas estimada pelo LiDAR apresentou tendência não significativa à subestimativa. A estimativa do DAP foi coerente com os valores encontrados no inventário florestal; porém, também mostrou tendência à subestimativa, em razão do comportamento observado quanto à altura. A variável número de fustes apresentou valores próximos aos observados nas parcelas do inventário. O LiDAR subestimou o volume total de madeira do talhão em 11,4%, em comparação ao volume posto na fábrica. A tendência de subestimação da altura das árvores (em média, cerca de 5%) impactou a estimativa do volume individual de árvores e, consequentemente, a do volume do talhão. No entanto, é possível gerar equações de regressão que estimam o DAP com boa precisão, a partir de dados de altura de plantas obtidos pelo LiDAR. O modelo parabólico é o que possibilita as melhores estimativas da produção volumétrica dos talhões de eucalipto.

Laser-MAG-hybridihitsauksen käyttöönotto laivan rungon valmistuksessa

Perinteisten kaarihitsausmenetelmien suhteellisen suuri lämmöntuonti aiheuttaa huomattavia muodonmuutoksia laivan rungon valmistusprosessin alkuvaiheessa. Muodonmuutosten seurauksena rakenteiden mitta- ja muototarkkuus heikkenee, mikä lisää oikaisu- ja sovitustyötä myöhemmissä työvaiheissa. Hitsausmuodonmuutoksia voidaan vähentää siirtymällä käyttämään laser-MAG-hybridihitsausta, jossa lämmöntuonti on merkittävästi pienempi kuin kaarihitsauksessa. Näin kyetään oleellisesti leikkaamaan oikaisu- ja sovitustyöstä syntyviä kustannuksia. Tämän diplomityön tavoitteena oli kehittää tuotantovalmiiksi kuitulaser- ja MAG-hitsauksen yhdistelmäprosessi Aker Yards Oy:n Turun telakalla loppuvuoden 2006 aikana. Hitsauslaitteiston asennus oli valmistunut kesäkuussa 2006, minkä jälkeen aloitettiin luokituslaitoksen hyväksymän koeohjelman hitsaukset. Käyttöönotto suunnitelmaan sisältyvä koehitsausohjelma oli laadittu Det Norske Veritaksen julkaisemaa ohjetta (Guidelines no. 19) mukaillen. Ensimmäiseksi määritettiin hitsauskokeiden avulla prosessille laadun ja tehokkuuden suhteen optimaalinen railogeometria. Seuraavaksi optimoitiin prosessin hitsausparametrit 6 mm:n aineenpaksuudelle hyödyntäen Taguchi-koesuunnittelumenetelmää. Tämän jälkeen optimiparametreilla hitsattiin koekappale väsytyskokeisiin, jotka suoritettiin Teknillisen korkeakoulun laivalaboratoriossa. Väsytyskoetulokset täyttivät luokituslaitoksen vaatimukset. Myös hitsauksen menetelmäkoe suoritettiin hyväksytetysti. Viimeinen koeohjelman mukainen hitsauskoesarja tehtiin prosessiparametrien sallittujen vaihtelurajojen määrittämiseksi. Diplomityön tavoite täyttyi joulukuussa 2006, jolloin 'laivan kansipaneeli hitsattiin ensimmäistä kertaa uudella hitsausprosessilla. Hitsauksen laatu korreloi hyvin menetelmäkokeen tulosten kanssa ¿ hitsit olivat tasalaatuisia ja ne täyttivät B-luokan vaatimukset.

CO2 Laser Cutting of Particleboard, HDF and MDF

The purpose of this thesis is to reveal how the laser cutting parameters influence lasercutting of particleboard, HDF and MDF. The literature review introduces the basic principle of CO2 laser, CO2 laser equipment and its usage in cutting of wood-based materials. The experimental part focuses on the discussion and analysis ofthe test data and attempts to draw conclusions on the influence of various parameters, including laser power, focal length of the lens and cutting gas, on the cutting speed and kerf quality. The tested materials include various thicknesses of particleboard, HDF and MDF samples. A TRUMPF TLF2700 HQ laser equipment was used for the experiments. To obtain valid data, the test samples must be completely cut through without any bonding of wood fibre. The maximum cutting speed is linear dependent on the laser power in thecondition that the other parameters are constant. For each thickness of a specific material type, there is a minimum laser power for cutting. Normally, the topand bottom kerf widths increase with the enhancement of laser power. There may be a critical laser power which can generate the minimum cross-sectional kerf width. Lens of larger focal length may achieve higher cutting speed. As the focal length becomes larger, the top kerf width tends to increase while the bottom andcross-sectional kerf widths to the opposite. Of all cutting gases, oxygen can help achieve higher cutting speed. The gas pressure of nitrogen does not seem to have strong influence on the cutting result. Generally, 2 bar air is more preferable for higher cutting speed. For particleboard and MDF samples of larger thickness than 12 mm, 2 bar argon can be used to reach remarkably higher cutting speed than the 5 bar. Generally, the 190.5 mm lens can produce smallest total kerf width. The kerf sides of thicker samples are darker than the thinner ones. The sample darkness tends to be lower as laser power increased. 63.5 mm lens seemed tocause more darkness than other lens. 5 bar cutting gases can produce less dark side kerfs than 2 bar ones. Oxygen normally causes darker kerfs than other gases. No distinct differences were found between nitrogen and argon.

Kinetics of selective oxidation of lactose to lactobionic acid over Pd-active carbon catalyst

Laktoosi eli maitosokeri on tärkein ainesosa useimpien nisäkkäiden tuottamassa maidossa. Sitä erotetaan herasta, juustosta ja maidosta. Laktoosia käytetään elintarvike- ja lääketeollisuuden raaka-aineena monissaeri tuotteissa. Lääketeollisuudessa laktoosia käytetään esimerkiksi tablettien täyteaineena. Hapettamalla laktoosia voidaan valmistaa laktobionihappoa, 2-keto-laktobionihappoa ja laktuloosia. Laktobionihappoa käytetään biohajoavien pintojen ja kosmetiikkatuotteiden valmistuksessa, sekä sisäelinten säilöntäliuoksissa, joissa laktobionihappo estää happiradikaalien aiheuttamien kudosvaurioiden syntymistä. Tässä työssä laktoosia hapetettiin laktobionihapoksi sekoittimella varustetussa laboratoriomittakaavaisessa panosreaktorissa käyttäenkatalyyttinä palladiumia aktiivihiilellä. Muutamissa kokeissa katalyytin promoottorina käytettiin vismuttia, joka hidastaa katalyytin deaktivoitumista. Työn tarkoituksena oli saada lisää tietoa laktoosin hapettamisen kinetiikasta. Laktoosin hapettumisessa laktobionihapoksi havaittiin selektiivisyyteen vaikuttavan muunmuassa reaktiolämpötila, paine, pH ja käytetyn katalyytin määrä. Katalyyttiä kierrättämällä eri kokeiden välillä saatiin paremmat konversiot, selektiivisyydet ja saannot. Parhaat koetulokset saatiin hapetettaessa synteettisellä ilmalla 60 oC lämpötilassa ja 1 bar paineessa. Tehdyissä kokeissa pH:n säätö tehtiin manuaalisesti, joten pH ei pysynyt koko ajan haluttuna. Laktoosin konversio oli parhaimmillaan 95 %. Laktobionihapon suhteellinen selektiivisyys oli 100% ja suhteellinen saanto 100 %. Kinetiikan matemaattinen mallinnus tehtiin Modest-ohjelmalla käyttäen kokeista saatuja mittaustuloksia.Ohjelman avulla estimoitiin parametreja ja saatiin matemaattinen malli reaktorille. Tässä työssä tehtiin kineettinen mallinnus myös ravistelureaktorissa tehdyille laktoosin hapetuskokeille, missä pH pysyi koko ajan haluttuna 'in-situ' titrauksen avulla. Työn yhteydessä selvitettiin myös mahdollisuutta käyttää monoliittikatalyyttejä laktoosin hapetusreaktiossa.

Nd:YAG Laser Welding of 5083 Aluminium Alloy using Filler Wire

High reflectivity and high thermal conductivity, high vapour pressure of alloyingelements as well as low liquid surface tension and low ionisation potential, make laser welding of aluminium and its alloys a demanding task.Problems that occur during welding are mainly process instabilities of the keyhole and the melt pool, increased plasma formation above the melt pool and loss of alloying elements. These problems lead to unwanted metallurgical defects like hot cracks and porosity in the weld bead andother problems concerning the shape and appearance of the weld bead. In order to minimise the defects and improve the weld quality, the process and beam parameters need to be carefully adjusted along with a consideration concerning the use of filler wire for the welding process. In this work the welding of 3,0 mm thick grade 5083 aluminium alloy plates using a 3,0 kW Nd:YAG laser with grade 5183 filler wire addition is investigated. The plates were welded as butt joints with air gap sizes 0,5 mm, 0,7mm and 1,0 mm. The analysis of the weld beads obtained from the weldedsamples showed that the least imperfections were produced with 0,7 mm air gaps at moderate welding speeds. The analysis also covered the calculation of the melting efficiency and the study of the shape of the weld bead. The melting efficiency was on average around 20 % for the melting process of the welded plates. The weld beads showed the characteristic V-shape of a laser weld and retained this shape during the whole series of experiments.

Effect of Shielding Gases in Laser Welding of Aluminium Alloys

High reflectivity to laser light, alloying element evaporation during high power laser welding makes aluminium alloys highly susceptibility to weld defects such as porosity, cracking and undercutting. The dynamic behaviour of the keyhole, due to fluctuating plasma above the keyhole and the vaporization ofthe alloying elements with in the keyhole, is the key problem to be solved for the improvement of the weld quality and stabilization of the keyhole dynamics isperhaps the single most important development that can broaden the application of laser welding of aluminium alloys. In laser welding, the shielding gas is commonly used to stabilize the welding process, to improve the welded joint features and to protect the welded seam from oxidation. The chemicalcomposition of the shielding gas is a key factor in achieving the final qualityof the welded joints. Wide range of shielding gases varying from the pure gasesto complex mixtures based on helium, argon, nitrogen and carbon dioxide are commercially available. These gas mixtures should be considered in terms of their suitability during laser welding of aluminium alloys to produce quality welds. The main objective of the present work is to study the effect of the shielding gascomposition during laser welding of aluminium alloys. Aluminium alloy A15754 was welded using 3kW Nd-YAG laser (continuous wave mode). The alloy samples were butt welded with different shielding gases (pure and mixture of gases) so that high quality welds with high joint efficiencies could be produced. It was observed that the chemical composition of the gases influenced the final weld quality and properties. In general, the mixture gases, in correct proportions, enabled better utilisation of the properties of the mixing gases, stabilized the welding process and produced better weld quality compared to the pure shielding gases.

Laser Cutting of Austenitic Stainless Steel with a High Quality Laser Beam

The thin disk and fiber lasers are new solid-state laser technologies that offer a combinationof high beam quality and a wavelength that is easily absorbed by metal surfacesand are expected to challenge the CO2 and Nd:YAG lasers in cutting of metals ofthick sections (thickness greater than 2mm). This thesis studied the potential of the disk and fiber lasers for cutting applications and the benefits of their better beam quality. The literature review covered the principles of the disk laser, high power fiber laser, CO2 laser and Nd:YAG laser as well as the principle of laser cutting. The cutting experiments were made with thedisk, fiber and CO2 lasers using nitrogen as an assist gas. The test material was austenitic stainless steel of sheet thickness 1.3mm, 2.3mm, 4.3mm and 6.2mm for the disk and fiber laser cutting experiments and sheet thickness of 1.3mm, 1.85mm, 4.4mm and 6.4mm for the CO2 laser cutting experiments. The experiments focused on the maximum cutting speeds with appropriate cut quality. Kerf width, cutedge perpendicularity and surface roughness were the cut characteristics used to analyze the cut quality. Attempts were made to draw conclusions on the influence of high beam quality on the cutting speed and cut quality. The cutting speeds were enormous for the disk and fiber laser cutting experiments with the 1.3mm and 2.3mm sheet thickness and the cut quality was good. The disk and fiber laser cutting speeds were lower at 4.3mm and 6.2mm sheet thickness but there was still a considerable percentage increase in cutting speeds compared to the CO2 laser cutting speeds at similar sheet thickness. However, the cut quality for 6.2mm thickness was not very good for the disk and fiber laser cutting experiments but could probably be improved by proper selection of cutting parameters.

In vitro evaluation of the temperature increment at the external root surface after Er,Cr: YSGG laser irradiation of the root canal

Objectives: A study was made to determine the temperature increment at the dental root surface following Er,Cr:YSGG laser irradiation of the root canal. Design. Human canines and incisors previously instrumented to K file number ISO 30 were used. Irradiation was carried out with glass fiber endodontic tips measuring 200 μm in diameter and especially designed for insertion in the root canal. The teeth were irradiated at 1 and 2 W for 30 seconds, without water spraying or air, and applying a continuous circular movement (approximately 2 mm/sec.) in the apico-coronal direction. Results: At the 1 W power setting, the mean temperature increment was 3.84ºC versus 5.01ºC at 2 W. In all cases the difference in mean value obtained after irradiation versus the mean baseline temperature proved statistically significant (p< 0.05). Conclusions: Application of the Er,Cr:YSGG laser gives rise to a statistically significant temperature increment at the external root surface, though this increment is probably clinically irrelevant, since it would appear to damage the tissues (periodontal ligament and alveolar bone) in proximity to the treated tooth

Visual measurement of laser-arc hybrid welding

Tässä työssä raportoidaan hybridihitsauksesta otettujen suurnopeuskuvasarjojen automaattisen analyysijärjestelmän kehittäminen.Järjestelmän tarkoitus oli tuottaa tietoa, joka avustaisi analysoijaa arvioimaan kuvatun hitsausprosessin laatua. Tutkimus keskittyi valokaaren taajuuden säännöllisyyden ja lisäainepisaroiden lentosuuntien mittaamiseen. Valokaaria havaittiin kuvasarjoista sumean c-means-klusterointimenetelmän avullaja perättäisten valokaarien välistä aikaväliä käytettiin valokaaren taajuuden säännöllisyyden mittarina. Pisaroita paikannettiin menetelmällä, jossa yhdistyi pääkomponenttianalyysi ja tukivektoriluokitin. Kalman-suodinta käytettiin tuottamaan arvioita pisaroiden lentosuunnista ja nopeuksista. Lentosuunnanmääritysmenetelmä luokitteli pisarat niiden arvioitujen lentosuuntien perusteella. Järjestelmän kehittämiseen käytettävissä olleet kuvasarjat poikkesivat merkittävästi toisistaan kuvanlaadun ja pisaroiden ulkomuodon osalta, johtuen eroista kuvaus- ja hitsausprosesseissa. Analyysijärjestelmä kehitettiin toimimaan pienellä osajoukolla kuvasarjoja, joissa oli tietynlainen kuvaus- ja hitsausprosessi ja joiden kuvanlaatu ja pisaroiden ulkomuoto olivat samankaltaisia, mutta järjestelmää testattiin myös osajoukon ulkopuolisilla kuvasarjoilla. Testitulokset osoittivat, että lentosuunnanmääritystarkkuus oli kohtuullisen suuri osajoukonsisällä ja pieni muissa kuvasarjoissa. Valokaaren taajuuden säännöllisyyden määritys oli tarkka useammassa kuvasarjassa.

Analytical methods for the quantitative determination of selective serotonin reuptake inhibitors for therapeutic drug monitoring purposes in patients.

Five selective serotonin reuptake inhibitors (SSRIs) have been introduced recently: citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline. Although no therapeutic window has been defined for SSRIs, in contrast to tricyclic antidepressants, analytical methods for therapeutic drug monitoring of SSRIs are useful in several instances. SSRIs differ widely in their chemical structure and in their metabolism. The fact that some of them have N-demethylated metabolites, which are also SSRIs, requires that methods be available which allow therapeutic drug monitoring of the parent compounds and of these active metabolites. most procedures are based on prepurification of the SSRIs by liquid-liquid extraction before they are submitted to separation by chromatographic procedures (high-performance liquid chromatography, gas chromatography, thin layer chromatography) and detection by various detectors (UV, fluorescence, electrochemical detector, nitrogen-phosphorus detector, mass spectrometry). This literature review shows that most methods allow quantitative determination of SSRIs in plasma, in the lower ng/ml range, and that they are, therefore, suitable for therapeutic drug monitoring purposes of this category of drugs.

Fiber Laser Cutting of Mild Steel

Fiber laser for materials processing have undergone a rapid development in the pastseveral years. As fiber laser provides a combination of high beam quality and awavelength that is easily absorbed by metal surfaces, the named future laser isexpected to challenge the CO2 and Nd:YAG lasers in the area of metal cutting. This thesis studied the performance of fiber laser cutting mild steel. In the literature review part, it introduced the laser cutting principle and the principle of fiber laser including the newest development of fiber laser cuttingtechnology. Because the fiber laser cutting mild steel is a very young technology, a preliminary test was made in order to investigate effect of the cutting parameters on cut quality. Then the formal fiber laser cutting experiment was madeby using 3 mm thickness S355 steel with oxygen as assistant gas. The experimentwas focused on the cut quality with maximum cutting speed and minimum oxygen gas pressure. And the cut quality is mainly decided by the kerf width, perpendicularity tolerance, surface roughness and striation patterns. After analysis the cutting result, several conclusions were made. Although the best result got in the experiment is not perfect as predicted, the whole result of the test can be accepted. Compared with CO2 laser, a higher cutting speed was achieved by fiber laser with very low oxygen gas pressure. A further improvement about the cutting quality might be possible by proper selection of process parameters. And in order to investigate the cutting performance more clearly, a future study about cutting different thickness mild steel and different shape was recommended.

Tuning the design procedures for laser processed microwave mechanics

This research has been focused at the development of a tuned systematic design methodology, which gives the best performance in a computer aided environment and utilises a cross-technological approach, specially tested with and for laser processed microwave mechanics. A tuned design process scheme is also presented. Because of the currently large production volumes of microwave and radio frequency mechanics even slight improvements of design methodologies or manufacturing technologies would give reasonable possibilities for cost reduction. The typical number of required iteration cycles could be reduced to one fifth of normal. The research area dealing with the methodologies is divided firstly into a function-oriented, a performance-oriented or a manufacturability-oriented product design. Alternatively various approaches can be developed for a customer-oriented, a quality-oriented, a cost-oriented or an organisation-oriented design. However, the real need for improvements is between these two extremes. This means that the effective methodology for the designers should not be too limited (like in the performance-oriented design) or too general (like in the organisation-oriented design), but it should, include the context of the design environment. This is the area where the current research is focused. To test the developed tuned design methodology for laser processing (TDMLP) and the tuned optimising algorithm for laser processing (TOLP), seven different industrial product applications for microwave mechanics have been designed, CAD-modelled and manufactured by using laser in small production series. To verify that the performance of these products meets the required level and to ensure the objectiveness ofthe results extensive laboratory tests were used for all designed prototypes. As an example a Ku-band horn antenna can be laser processed from steel in 2 minutes at the same time obtaining a comparable electrical performance of classical aluminium units or the residual resistance of a laser joint in steel could be limited to 72 milliohmia.

Selective catalytic reduction of nitrogen oxides with ammonia in forced unsteady state reactors - Case based reasoning and mathematical model simulation reasoning

The application of forced unsteady-state reactors in case of selective catalytic reduction of nitrogen oxides (NOx) with ammonia (NH3) is sustained by the fact that favorable temperature and composition distributions which cannot be achieved in any steady-state regime can be obtained by means of unsteady-state operations. In a normal way of operation the low exothermicity of the selective catalytic reduction (SCR) reaction (usually carried out in the range of 280-350°C) is not enough to maintain by itself the chemical reaction. A normal mode of operation usually requires supply of supplementary heat increasing in this way the overall process operation cost. Through forced unsteady-state operation, the main advantage that can be obtained when exothermic reactions take place is the possibility of trapping, beside the ammonia, the moving heat wave inside the catalytic bed. The unsteady state-operation enables the exploitation of the thermal storage capacity of the catalyticbed. The catalytic bed acts as a regenerative heat exchanger allowing auto-thermal behaviour when the adiabatic temperature rise is low. Finding the optimum reactor configuration, employing the most suitable operation model and identifying the reactor behavior are highly important steps in order to configure a proper device for industrial applications. The Reverse Flow Reactor (RFR) - a forced unsteady state reactor - corresponds to the above mentioned characteristics and may be employed as an efficient device for the treatment of dilute pollutant mixtures. As a main disadvantage, beside its advantages, the RFR presents the 'wash out' phenomena. This phenomenon represents emissions of unconverted reactants at every switch of the flow direction. As a consequence our attention was focused on finding an alternative reactor configuration for RFR which is not affected by the incontrollable emissions of unconverted reactants. In this respect the Reactor Network (RN) was investigated. Its configuration consists of several reactors connected in a closed sequence, simulating a moving bed by changing the reactants feeding position. In the RN the flow direction is maintained in the same way ensuring uniformcatalyst exploitation and in the same time the 'wash out' phenomena is annulated. The simulated moving bed (SMB) can operate in transient mode giving practically constant exit concentration and high conversion levels. The main advantage of the reactor network operation is emphasizedby the possibility to obtain auto-thermal behavior with nearly uniformcatalyst utilization. However, the reactor network presents only a small range of switching times which allow to reach and to maintain an ignited state. Even so a proper study of the complex behavior of the RN may give the necessary information to overcome all the difficulties that can appear in the RN operation. The unsteady-state reactors complexity arises from the fact that these reactor types are characterized by short contact times and complex interaction between heat and mass transportphenomena. Such complex interactions can give rise to a remarkable complex dynamic behavior characterized by a set of spatial-temporal patterns, chaotic changes in concentration and traveling waves of heat or chemical reactivity. The main efforts of the current research studies concern the improvement of contact modalities between reactants, the possibility of thermal wave storage inside the reactor and the improvement of the kinetic activity of the catalyst used. Paying attention to the above mentioned aspects is important when higher activity even at low feeding temperatures and low emissions of unconverted reactants are the main operation concerns. Also, the prediction of the reactor pseudo or steady-state performance (regarding the conversion, selectivity and thermal behavior) and the dynamicreactor response during exploitation are important aspects in finding the optimal control strategy for the forced unsteady state catalytic tubular reactors. The design of an adapted reactor requires knowledge about the influence of its operating conditions on the overall process performance and a precise evaluation of the operating parameters rage for which a sustained dynamic behavior is obtained. An apriori estimation of the system parameters result in diminution of the computational efforts. Usually the convergence of unsteady state reactor systems requires integration over hundreds of cycles depending on the initial guess of the parameter values. The investigation of various operation models and thermal transfer strategies give reliable means to obtain recuperative and regenerative devices which are capable to maintain an auto-thermal behavior in case of low exothermic reactions. In the present research work a gradual analysis of the SCR of NOx with ammonia process in forced unsteady-state reactors was realized. The investigation covers the presentationof the general problematic related to the effect of noxious emissions in the environment, the analysis of the suitable catalysts types for the process, the mathematical analysis approach for modeling and finding the system solutions and the experimental investigation of the device found to be more suitable for the present process. In order to gain information about the forced unsteady state reactor design, operation, important system parameters and their values, mathematical description, mathematicalmethod for solving systems of partial differential equations and other specific aspects, in a fast and easy way, and a case based reasoning (CBR) approach has been used. This approach, using the experience of past similarproblems and their adapted solutions, may provide a method for gaining informations and solutions for new problems related to the forced unsteady state reactors technology. As a consequence a CBR system was implemented and a corresponding tool was developed. Further on, grooving up the hypothesis of isothermal operation, the investigation by means of numerical simulation of the feasibility of the SCR of NOx with ammonia in the RFRand in the RN with variable feeding position was realized. The hypothesis of non-isothermal operation was taken into account because in our opinion ifa commercial catalyst is considered, is not possible to modify the chemical activity and its adsorptive capacity to improve the operation butis possible to change the operation regime. In order to identify the most suitable device for the unsteady state reduction of NOx with ammonia, considering the perspective of recuperative and regenerative devices, a comparative analysis of the above mentioned two devices performance was realized. The assumption of isothermal conditions in the beginningof the forced unsteadystate investigation allowed the simplification of the analysis enabling to focus on the impact of the conditions and mode of operation on the dynamic features caused by the trapping of one reactant in the reactor, without considering the impact of thermal effect on overall reactor performance. The non-isothermal system approach has been investigated in order to point out the important influence of the thermal effect on overall reactor performance, studying the possibility of RFR and RN utilization as recuperative and regenerative devices and the possibility of achieving a sustained auto-thermal behavior in case of lowexothermic reaction of SCR of NOx with ammonia and low temperature gasfeeding. Beside the influence of the thermal effect, the influence of the principal operating parameters, as switching time, inlet flow rate and initial catalyst temperature have been stressed. This analysis is important not only because it allows a comparison between the two devices and optimisation of the operation, but also the switching time is the main operating parameter. An appropriate choice of this parameter enables the fulfilment of the process constraints. The level of the conversions achieved, the more uniform temperature profiles, the uniformity ofcatalyst exploitation and the much simpler mode of operation imposed the RN as a much more suitable device for SCR of NOx with ammonia, in usual operation and also in the perspective of control strategy implementation. Theoretical simplified models have also been proposed in order to describe the forced unsteady state reactors performance and to estimate their internal temperature and concentration profiles. The general idea was to extend the study of catalytic reactor dynamics taking into account the perspectives that haven't been analyzed yet. The experimental investigation ofRN revealed a good agreement between the data obtained by model simulation and the ones obtained experimentally.