Backpressure effects on the flow-pressure relation of driplines

ABSTRACT For drip irrigation design and management, it is necessary to know the relation between flow and pressure acting on emitters. In the case of subsurface drip irrigation, the backpressure phenomenon may change the hydraulic characteristics of emitters. Thus, this study aimed at determining such relationship between flow and pressure of different driplines in surface and subsurface conditions; aiming to find possible differences in hydraulic behavior. We tested four emitter types; two pressure compensating (D5000 and Hydro PCND) and two non-pressure compensating (TalDrip and Jardiline). Emitter flow rates were attained in atmospheric conditions and submerged in water, in which submergence levels represented backpressure. Assays were performed using inlet pressures of 80, 100, 120, and 150 kPa for the Hydro PCND dripline and 25, 50, 100, and 150 kPa for the other ones; the backpressures were of 0.49, 1.47, 2.45, 4.41 and 6.37 kPa with four replications. The emitters had their proportionality constants and discharge exponents changed in submerged applications, representing backpressure effect. Non-pressure compensating emitters had their discharge exponent decreased, while in pressure compensating ones, it was increased. Backpressure reduced emitter flow rates at all evaluated pressures.

Energian talteenotto liikkuvassa raskaassa työkoneessa

Tämä työ on osa Integrated Serial and Parallel Hybrid Drives in Working Machines projektia. Työssä simuloidaan ja lasketaan energian palautuspotentiaalia raskaassa liikkuvassa työkoneessa. Työn alussa aihetta käsitellään yleisesti kirjallisuuskatsauksen muodossa. Tukkikurottaja valittiin simulointien ja laskennan kohteeksi. Työssä suoritettiin alustavat simuloinnit, joiden tarkoituksena oli varmistua, että palautettavaa energiaa on olemassa. Tulokset osoittavat, että energian palauttaminen on mahdollista. Mittaukset ovat osa työtä. Mitatut muuttujat ovat paineet ja pituudet hydraulisylintereistä, rungon kiihtyvyys, sekä kaikki CAN-väylään kytkettyjen antureiden mittaustiedot. Lopulliset simuloinnit perustuvat mitattuihin työkiertoihin. Työsylintereiden ja ajovoimansiirron tehotarpeet valittiin simulointien tarkasteltaviksi mittaussuureiksi. Mahdollinen palautettavan energian määrä eri työkierroissa on työn lopputulos. Tulokset osoittavat, että palautettavan energian määrä on talteenoton kannalta riittävä.

Virtuaalimallin hyödyntäminen harvesteripään tuotekehityksessä

Virtuaalimallinnuksella tarkoitetaan koneen simulointia, jossa huomioidaan koneen mekaniikka, toimilaitteet ja ohjausjärjestelmä. Työn tavoitteena oli luoda virtuaalimalli harvesteripäästä. Kyseinen virtuaalimalli sisälsi harvesteripään tärkeimmät mekaaniset osat, pituusmittalaitteen hydrauliikkapiirin ja tämän ohjauksen. Luodussa virtuaalimallissa huomioitiin myös harvesteripään ja puun väliset kontaktit. Lisäksi työssä tutkittiin mahdollista virtuaalimallinnuksen implementoimista osaksi yrityksen tuotekehitysprosessia. Työssä suoritettiin verifiointimittaukset pituusmittalaitteen hydrauliikkapiirille sekä virtuaalimallin hydrauliikkakomponentit parametrisoitiin. Mittauksista saatuja tuloksia verrattiin virtuaalimallista saatuihin tuloksiin. Työssä esitellään myös ehdotus kuinka virtuaalimallinnusta kannattaisi hyödyntää osana yrityksen tuotekehitysprosessia. Virtuaalimallin eri osa-alueilla saavutetut tulokset osoittavat, että virtuaalimallinuksen hyödyntäminen tuotekehitysprosessin aikana mahdollistaa harvesteripään toimintojen tarkastelun ennen prototyypin rakentamista ja testaamista. Lisäksi hydrauliikkapiirin parametrisoimisella pystytään tutkimaan parametrien vaikutusta kokonaisuuteen.

Virtual technology and haptic interface solutions for design and control of mobile working machines

Commercially available haptic interfaces are usable for many purposes. However, as generic devices they are not the most suitable for the control of heavy duty mobile working machines like mining machines, container handling equipment and excavators. Alternative mechanical constructions for a haptic controller are presented and analysed. A virtual reality environment (VRE) was built to test the proposed haptic controller mechanisms. Verification of an electric motor emulating a hydraulic pump in the electro-hydraulic system of a mobile working machine is carried out. A real-time simulator using multi-body-dynamics based software with hardware-in-loop (HIL) setup was used for the tests. Recommendations for further development of a haptic controller and emulator electric motor are given.

Arc fusion of self-fluxed nickel alloys

Self-fluxed nickel alloys are usually flame fused after thermal spraying. However, due to the practical aspects of high temperatures reached during flame fusing, large structures such as the hydraulic turbines for power generation, can not be efficiently coated. An alternative is to fuse the sprayed coating with a gas tungsten electric arc. In this case, heating is much more intensive and substrate temperature during and after the fusing operation is much lower, thus reducing the possibility that any problem will occur. In this work, coatings of self-fluxed nickel alloy fused by flame and gas tungsten arc were evaluated as protection of hydraulic turbines against cavitational damage. Several tests were performed, including the ASTM ultrasonically vibration-induced cavitation, optical and scanning electronic microscopic metallography, and hardness tests. The results showed that the arc-fused coating presented better cavitation damage resistance, probably due to its finer microstructure. A field application of this new technique is also described. A self-fluxed Ni alloy was flame sprayed in critical regions of Francis-type hydraulic turbine blades and fused by a gas tungsten arc after spraying. The blades will be inspected during the next two years.

Onset of Nucleate Boiling and Onset of Fully Developed Subcooled Boiling Using Pressure Transducers Signals Spectral Analysis

The experimental technique used for detection of subcooled boiling through analysis of the fluctuation contained in pressure transducer signals is presented. This work was partly conducted at the Institut für Kerntechnik und zertörungsfreie Prüfverfahren von Hannover (IKPH, Germany) in a thermal-hydraulic circuit with one electrically heated rod with annular geometry test section. Piezoresistive pressure sensors are used for onset of nucleate boiling (ONB) and onset of fully developed boiling (OFDB) detection using spectral analysis/ signal correlation techniques. Experimental results are interpreted by phenomenological analysis of these two points and compared with existing correlation. The results allow us to conclude that this technique is adequate for the detection and monitoring of the ONB and OFDB.

Tooth-Coil Permanent Magnet Synchronous Machine Design for Special Applications

This doctoral thesis presents a study on the design of tooth-coil permanent magnet synchronous machines. The electromagnetic properties of concentrated non-overlapping winding permanent magnet synchronous machines, or simply tooth-coil permanent magnet synchronous machines (TC-PMSMs), are studied in details. It is shown that current linkage harmonics play the deterministic role in the behavior of this type of machines. Important contributions are presented as regards of calculation of parameters of TC-PMSMs,particularly the estimation of inductances. The current linkage harmonics essentially define the air-gap harmonic leakage inductance, rotor losses and localized temporal inductance variation. It is proven by FEM analysis that inductance variation caused by the local temporal harmonic saturation results in considerable torque ripple, and can influence on sensorless control capabilities. Example case studies an integrated application of TC-IPMSMs in hybrid off-highway working vehicles. A methodology for increasing the efficiency of working vehicles is introduced. It comprises several approaches – hybridization, working operations optimization, component optimization and integration. As a result of component optimization and integration, a novel integrated electro-hydraulic energy converter (IEHEC) for off-highway working vehicles is designed. The IEHEC can considerably increase the operational efficiency of a hybrid working vehicle. The energy converter consists of an axial-piston hydraulic machine and an integrated TCIPMSM being built on the same shaft. The compact assembly of the electrical and hydraulic machines enhances the ability to find applications for such a device in the mobile environment of working vehicles.Usage of hydraulic fluid, typically used in working actuators, enables direct-immersion oil cooling of designed electrical machine, and further increases the torque- and power- densities of the whole device.

Dynamiikan simulointi poralaitteiden tuotekehityksessä

Diplomityö käsittelee kallioporalaitteen eliniän kuormitusten arviointiin tarkoitetun simulointimallin rakentamista. Työssä luotiin modulaarinen malli, jolla voidaan simuloida dynaamisesti esteen yliajo. Esteen yliajo on perinteinen tehdastesti uusien laitteiden prototyypeille. Sillä pyritään saamaan selville laitteen maksimikuormitustapaukset. Pintaporalaitteen simulointimalli tehtiin ADAMS-ohjelmistolla laitteen suunnittelussa tehtyjä CAD-malleja hyödyntäen. ADAMS-ohjelmistolla mallinnettiin laitteen yksinkertaistettu mekaniikka siten, että laite oli jaettu viiteen eri moduuliin. Runko ja telasto olivat omana osionaan. Puomi ja syöttölaite oli oma kokoonpanonsa ja ohjaamo sekä katteet olivat kaksi erillistä modulia. Viides moduuli oli hydrauliikka, joka simuloitiin rinnakkaissimulointina EASY5-ohjelmistolla. Simuloituja esteen yliajon tuloksia verrattiin prototyyppilaitteen tehdastestien mitattuihin kuormituksiin. Vertailu tehtiin mallinnettujen neljän sylinterin paineita tarkastelemalla. Tuloksia tarkastellessa havaittiin, että simulaatiomalli antaa varsinkin staattisissa tarkasteluissa oikean suuntaisia tuloksia. Dynaamisissa tilanteissa koneen maksimikuormituksilla mallinnustarkkuus ei tämän työn laajuudessa ole riittävä varsinaiseen eliniän analysointiin. Sen sijaan mallinnustekniikka todettiin periaatteessa toimivaksi ja jatkokehityskelpoiseksi.

Modelling of hydrogen stratification and gas mixing in containment using the APROS code

Hydrogen stratification and atmosphere mixing is a very important phenomenon in nuclear reactor containments when severe accidents are studied and simulated. Hydrogen generation, distribution and accumulation in certain parts of containment may pose a great risk to pressure increase induced by hydrogen combustion, and thus, challenge the integrity of NPP containment. The accurate prediction of hydrogen distribution is important with respect to the safety design of a NPP. Modelling methods typically used for containment analyses include both lumped parameter and field codes. The lumped parameter method is universally used in the containment codes, because its versatility, flexibility and simplicity. The lumped parameter method allows fast, full-scale simulations, where different containment geometries with relevant engineering safety features can be modelled. Lumped parameter gas stratification and mixing modelling methods are presented and discussed in this master’s thesis. Experimental research is widely used in containment analyses. The HM-2 experiment related to hydrogen stratification and mixing conducted at the THAI facility in Germany is calculated with the APROS lump parameter containment package and the APROS 6-equation thermal hydraulic model. The main purpose was to study, whether the convection term included in the momentum conservation equation of the 6-equation modelling gives some remarkable advantages compared to the simplified lumped parameter approach. Finally, a simple containment test case (high steam release to a narrow steam generator room inside a large dry containment) was calculated with both APROS models. In this case, the aim was to determine the extreme containment conditions, where the effect of convection term was supposed to be possibly high. Calculation results showed that both the APROS containment and the 6-equation model could model the hydrogen stratification in the THAI test well, if the vertical nodalisation was dense enough. However, in more complicated cases, the numerical diffusion may distort the results. Calculation of light gas stratification could be probably improved by applying the second order discretisation scheme for the modelling of gas flows. If the gas flows are relatively high, the convection term of the momentum equation is necessary to model the pressure differences between the adjacent nodes reasonably.

Hydraulisen puomin avoimen piirin koordinaattiohjaus paine-ero-tilavuusvirta-approksimaation avulla

Diplomityön tavoitteena oli kehittää mahdollisimman hyvä koordinaattiohjaus. Sen tuli olla jälkiasennettavissa perinteisen ohjauksen rinnalle työkoneisiin, joissa on käytetty sähköohjattuja proportionaaliventtiileitä. Työssä keskityttiin tutkimaan suuntaventtiilin yli vallitsevasta paine-erosta saatavan tilavuusvirtatiedon hyödyntämistä ohjauksessa. Työn ensimmäisessä vaiheessa koordinaattiohjaus toteutettiin käyttäen 0-peittoisilla karoilla ja karan asematakaisinkytkennällä varustettuja suuntaventtiileitä. Hydrauliseen kuristukseen perustuen saatiin paine-erosta käyttökelpoista tilavuusvirtasignaalia ja koordinaattiohjauksen liikeradan seurannassa oli parhaimmillaan vain 3 cm:n virhe koenosturin työliikkeen pituudella. Toisessa vaiheessa käytettiin työkoneissa yleisesti esiintyvää positiivisin karapeitoin varustettua mobiiliventtiilistöä, jossa oli karakohtaiset painekompensaattorit. Painekompensaattoreiden takia ei paine-eron mittaaminen puhtaasti suuntaventtiilin karan yli ollut mahdollista, jonka takia tyydyttiin koordinaattiohjaus toteuttamaan ilman paineen mittausta luottaen painekompensaattoreiden toimintaan. Käytetyn venttiilistön kavitoinninestotoiminnon huomiointi ohjauksessa jäi ratkaisematta ja se ohitettiin vastusvastaventtiileiden avulla. Koordinaattiohjauksen tarkkuus mobiiliventtiileillä oli vaatimaton ja tulosten toistettavuus heikko. Tulosten perusteella todettiin avoimellakin koordinaattiohjauksella olevan mahdollista saavuttaa lupaava tarkkuus ammattikuljettajiin verrattuna. Mobiiliventtiilistöön liittyvät, työn aikana esiinnousseet epäkohdat olisi ratkaistava ennen käytettyjen menetelmien soveltamista käytännön kohteisiin.

Flexible multibody dynamics and intelligent control of a hydraulically driven hybrid redundant robot machine

The assembly and maintenance of the International Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV) is highly challenging since the tasks performed by the robot involve welding, material handling, and machine cutting from inside the VV. The VV is made of stainless steel, which has poor machinability and tends to work harden very rapidly, and all the machining operations need to be carried out from inside of the ITER VV. A general industrial robot cannot be used due to its poor stiffness in the heavy duty machining process, and this will cause many problems, such as poor surface quality, tool damage, low accuracy. Therefore, one of the most suitable options should be a light weight mobile robot which is able to move around inside of the VV and perform different machining tasks by replacing different cutting tools. Reducing the mass of the robot manipulators offers many advantages: reduced material costs, reduced power consumption, the possibility of using smaller actuators, and a higher payload-to-robot weight ratio. Offsetting these advantages, the lighter weight robot is more flexible, which makes it more difficult to control. To achieve good machining surface quality, the tracking of the end effector must be accurate, and an accurate model for a more flexible robot must be constructed. This thesis studies the dynamics and control of a 10 degree-of-freedom (DOF) redundant hybrid robot (4-DOF serial mechanism and 6-DOF 6-UPS hexapod parallel mechanisms) hydraulically driven with flexible rods under the influence of machining forces. Firstly, the flexibility of the bodies is described using the floating frame of reference method (FFRF). A finite element model (FEM) provided the Craig-Bampton (CB) modes needed for the FFRF. A dynamic model of the system of six closed loop mechanisms was assembled using the constrained Lagrange equations and the Lagrange multiplier method. Subsequently, the reaction forces between the parallel and serial parts were used to study the dynamics of the serial robot. A PID control based on position predictions was implemented independently to control the hydraulic cylinders of the robot. Secondly, in machining, to achieve greater end effector trajectory tracking accuracy for surface quality, a robust control of the actuators for the flexible link has to be deduced. This thesis investigates the intelligent control of a hydraulically driven parallel robot part based on the dynamic model and two schemes of intelligent control for a hydraulically driven parallel mechanism based on the dynamic model: (1) a fuzzy-PID self-tuning controller composed of the conventional PID control and with fuzzy logic, and (2) adaptive neuro-fuzzy inference system-PID (ANFIS-PID) self-tuning of the gains of the PID controller, which are implemented independently to control each hydraulic cylinder of the parallel mechanism based on rod length predictions. The serial component of the hybrid robot can be analyzed using the equilibrium of reaction forces at the universal joint connections of the hexa-element. To achieve precise positional control of the end effector for maximum precision machining, the hydraulic cylinder should be controlled to hold the hexa-element. Thirdly, a finite element approach of multibody systems using the Special Euclidean group SE(3) framework is presented for a parallel mechanism with flexible piston rods under the influence of machining forces. The flexibility of the bodies is described using the nonlinear interpolation method with an exponential map. The equations of motion take the form of a differential algebraic equation on a Lie group, which is solved using a Lie group time integration scheme. The method relies on the local description of motions, so that it provides a singularity-free formulation, and no parameterization of the nodal variables needs to be introduced. The flexible slider constraint is formulated using a Lie group and used for modeling a flexible rod sliding inside a cylinder. The dynamic model of the system of six closed loop mechanisms was assembled using Hamilton’s principle and the Lagrange multiplier method. A linearized hydraulic control system based on rod length predictions was implemented independently to control the hydraulic cylinders. Consequently, the results of the simulations demonstrating the behavior of the robot machine are presented for each case study. In conclusion, this thesis studies the dynamic analysis of a special hybrid (serialparallel) robot for the above-mentioned special task involving the ITER and investigates different control algorithms that can significantly improve machining performance. These analyses and results provide valuable insight into the design and control of the parallel robot with flexible rods.

Water relations of tree species growing on a rock outcrop in the "Parque Estadual de Itapuã", RS

Water relations of the tree species Myrsine umbellata Mart. ex A. DC., Dodonaea viscosa Jacq. and Erythroxylum argentinum O. E. Schulz, growing on a rock outcrop in the "Parque Estadual de Itapuã" (RS), were studied. Environmental (precipitation, temperature, soil water) and plant (water potential, vapor pressure deficit, stomatal conductance, transpiration, leaf specific hydraulic conductance, osmotic potential and cell wall elasticity) parameters were collected in five periods and pooled into two sets of data: wet and dry periods. Myrsine umbellata showed great stability of the plant parameters, including the maintenance of high pre-dawn (psiwpd) and mid-day (psiwmd) water potentials in the dry period (-0.48 and -1.12 MPa, respectively), suggesting the presence of a deep root system. Dodonaea viscosa and E. argentinum reached lower psiwpd (-1.41 and -1.97 MPa, respectively) and a greater degree of stomatal closure in the dry period, suggesting a shallower root system. Differential exposure to soil drought was also corroborated by differential drought effects on the whole-plant leaf specific hydraulic conductance (Gt). Correlation analysis pointed to weak correlations between psiwpd and g s. Erythroxylum argentinum was the only species to show osmotic adjustment in response to drought. It is suggested that M. umbellata has low tolerance to water deficits, adopting an avoidance behavior. The much lower values of psiw reached by D. viscosa and E. argentinum suggest a greater tolerance to drought by these species.

Heterogeneity of glomerular perfusion and filtration induced by epinephrine and norepinephrine

The role of catecholamines in the distribution of intrarenal blood flow and in single-nephron glomerular filtration rate (SNGFR) was evaluated in anesthetized Wistar rats by the Hanssen technique. Epinephrine (EPI) and norepinephrine (NOR) were infused to produce elevations of 20-30 mmHg in mean arterial pressure. Superficial and juxtamedullary nephron perfusion and filtration were determined by the presence of Prussian blue dye. In the control group, 100% of the nephrons presented a homogeneous pattern of perfusion and filtration. In contrast, a heterogeneous distribution of the dye was found even in the larger arteries (arciform and radial), indicating variable perfusion and filtration in both superficial and juxtamedullary nephrons. The effects of EPI and NOR were also evaluated in the superficial cortex by the micropuncture technique in two additional groups of Munich-Wistar rats. Mean SNGFR was 27% and 54% lower in the EPI- and NOR-treated groups, respectively. No change in mean intraglomerular hydraulic pressure was observed after EPI or NOR infusion in spite of a highly scattered pattern, indicating an important variability in perfusion along the superficial cortex, and/or different sensitivity of the pre- and post-glomerular arterioles. The present data suggest that EPI and NOR may affect intrarenal hemodynamics by modifying perfusion and filtration in both superficial and juxtamedullary glomeruli and not by shifting blood flow from superficial to juxtamedullary nephrons. The heterogeneous pattern of perfusion was a consequence of differential vasoconstriction along the intrarenal arteries, probably due to different density and/or sensitivity of the adrenergic receptor subtypes present in the intrarenal vascular tree.

Virtuaalisimuloinnin käytettävyys PF-suodattimien hydraulijärjestelmien koulutuksessa, analysoinnissa ja vianmäärityksessä

Tämän työn tavoitteena oli luoda koulutusmateriaalia PF-suodattimien hydraulijärjestelmien koulutusta varten sekä selvittää Automation Studio-ohjelmiston soveltuvuutta PF-suodattimien analysointiin ja vianmääritykseen. Työssä tutkittiin myös aktivoivien koulutusmenetelmien vaikutusta oppimisprosessiin. Työn tärkeimpinä tuloksina saatiin opetusvideot PF-suodattimien hydraulijärjestelmissä käytettävistä peruskomponenteista sekä järjestelmien toimintaa kuvaavat opetusvideot. Työssä käytettyä mallinnus- ja simulointiohjelmistoa ei voida nykyisellä ohjelmaversiolla täysin soveltaa PF-suodattimien vianmääritykseen tai analysointiin. Työssä selvennettiin menestyksekkään vianmäärityksen ja analysoinnin kannalta tarvittavat laajennustarpeet ohjelmistoon. Koulutuksesta kerätyn palautteen perusteella opetusvideot yhdistettynä aktivoiviin koulutusmenetelmiin helpottavat PF-suodattimien hydraulijärjestelmien koulutusta sekä edistävät oppimisprosessia. Aktivoivia koulutusmenetelmiä voidaan pitää erityisesti soveltuvina aikuiskoulutukseen.