Anaerobic reactors with biofilter and different diameter-length ratios in cassava starch industry wastewater treatment

The use of anaerobic reactors with media support in the treatment of wastewater from the cassava starch industry has emerged as a viable option because it allows the application of high organic loads and a significant reduction of the HDT needed for the treatment. This research aimed at studying the process of biodigestion in two anaerobic reactors with bamboo support, in the treatment of effluent of cassava starch, by evaluating their performance. The two reactors used present the following diameter: length ratio, 1:6 and 1:3. The organic loads applied to the systems were 0.519, 1.156, 1.471, 3.049, 4.347, 4.708 and 5.601g.L-1.d-1. Regarding the efficiency of removal of COD, TS and TVS, no statistically significant differences were obtained between the reactors. The two systems evaluated showed a stable behavior with respect to the VA/TA (volatile acidity/total alkalinity) for all submitted loads. The reactors tended to the maintenance of biogas production as a function of consumed COD for the last three organic loads applied, indicating an ability to withstand higher organic loads.

Motores de reacción modernos por turbinas de gas

This Bachelor’s thesis investigates the different types of jet engines used nowadays, their performance and applications. The thesis includes a general study of dynamics of fly, engine thermodynamics and contamination.

Optimization as a method of search engine marketing

This study is dedicated to search engine marketing (SEM). It aims for developing a business model of SEM firms and to provide explicit research of trustworthy practices of virtual marketing companies. Optimization is a general term that represents a variety of techniques and methods of the web pages promotion. The research addresses optimization as a business activity, and it explains its role for the online marketing. Additionally, it highlights issues of unethical techniques utilization by marketers which created relatively negative attitude to them on the Internet environment. Literature insight combines in the one place both technical and economical scientific findings in order to highlight technological and business attributes incorporated in SEM activities. Empirical data regarding search marketers was collected via e-mail questionnaires. 4 representatives of SEM companies were engaged in this study to accomplish the business model design. Additionally, the fifth respondent was a representative of the search engine portal, who provided insight on relations between search engines and marketers. Obtained information of the respondents was processed qualitatively. Movement of commercial organizations to the online market increases demand on promotional programs. SEM is the largest part of online marketing, and it is a prerogative of search engines portals. However, skilled users, or marketers, are able to implement long-term marketing programs by utilizing web page optimization techniques, key word consultancy or content optimization to increase web site visibility to search engines and, therefore, user’s attention to the customer pages. SEM firms are related to small knowledge-intensive businesses. On the basis of data analysis the business model was constructed. The SEM model includes generalized constructs, although they represent a wider amount of operational aspects. Constructing blocks of the model includes fundamental parts of SEM commercial activity: value creation, customer, infrastructure and financial segments. Also, approaches were provided on company’s differentiation and competitive advantages evaluation. It is assumed that search marketers should apply further attempts to differentiate own business out of the large number of similar service providing companies. Findings indicate that SEM companies are interested in the increasing their trustworthiness and the reputation building. Future of the search marketing is directly depending on search engines development.

Heat transfer inside internal combustion engine: modelling and comparison with experimental data

The paper is devoted to study specific aspects of heat transfer in the combustion chamber of compression ignited reciprocating internal combustion engines and possibility to directly measure the heat flux by means of Gradient Heat Flux Sensors (GHFS). A one – dimensional single zone model proposed by Kyung Tae Yun et al. and implemented with the aid of Matlab, was used to obtain approximate picture of heat flux behavior in the combustion chamber with relation to the crank angle. The model’s numerical output was compared to the experimental results. The experiment was accomplished by A. Mityakov at four stroke diesel engine Indenor XL4D. Local heat fluxes on the surface of cylinder head were measured with fast – response, high – sensitive GHFS. The comparison of numerical data with experimental results has revealed a small deviation in obtained heat flux values throughout the cycle and different behavior of heat flux curve after Top Dead Center.

Heat flux measurement inside internal combustion engine with gradient heat flux sensor.

This master’s thesis is devoted to study different heat flux measurement techniques such as differential temperature sensors, semi-infinite surface temperature methods, calorimetric sensors and gradient heat flux sensors. The possibility to use Gradient Heat Flux Sensors (GHFS) to measure heat flux in the combustion chamber of compression ignited reciprocating internal combustion engines was considered in more detail. A. Mityakov conducted an experiment, where Gradient Heat Flux Sensor was placed in four stroke diesel engine Indenor XL4D to measure heat flux in the combustion chamber. The results which were obtained from the experiment were compared with model’s numerical output. This model (a one – dimensional single zone model) was implemented with help of MathCAD and the result of this implementation is graph of heat flux in combustion chamber in relation to the crank angle. The values of heat flux throughout the cycle obtained with aid of heat flux sensor and theoretically were sufficiently similar, but not identical. Such deviation is rather common for this type of experiment.

Konversiosähköauton mitoitussuunnitelma

Sähköautojen tulemista on odotettu jo pitkään ja ne ovat potentiaalisia fossiilisilla polttoaineilla toimivien polttomoottoreiden korvaajia. Hybridiautoja on tullut markkinoille entistä enemmän ja ne osaltaan auttavat vähentämään fossiilisten polttoaineiden käyttöä. Sähköautot ovat toistaiseksi jääneet taka-alalle. Tässä työssä on tehty konversiosähköauton mitoitussuunnitelma museoikäiseen autoon. Työssä on mitoitettu kolme sähköisen voimansiirron pääkomponenttia sähkömoottori, taajuudenmuuttaja ja akusto. Mitoitussuunnitelma toimii hyvänä pohjana, jonka avulla konversiota voidaan alkaa rakentamaan.

Thermal radiation in combustion systems

A numerical procedure for solving the nongray radiative transfer equation (RTE) in two-dimensional cylindrical participating media is presented. Nongray effects are treated by using a narrow-band approach. Radiative emission from CO, CO2, H2O, CH4 and soot is considered. The solution procedure is applied to study radiative heat transfer in a premixed CH4-O2, laminar, flame. Temperature, soot and IR-active species molar fraction distributions are allowed to vary in the axial direction of the flame. From the obtained results it is possible to quantify the radiative loss in the flame, as well as the importance of soot radiation as compared to gaseous radiation. Since the solution procedure is developed for a two-dimensional cylindrical geometry, it can be applied to other combustion systems such as furnaces, internal combustion engines, liquid and solid propellant combustion.

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.

Työkoneiden dieselmoottoreiden hyötysuhteen parantaminen lämmöntalteenoton avulla

Tämä diplomityö on osa Lappeenrannan teknillisessä yliopistossa tehtävää tutkimusta polttomoottoreiden energiatehokkuuden parantamisessa. Työn tavoitteena on saada tutkimustietoa polttomoottoreiden hukkalämpövirtojen hyödyntämisestä sähköntuotannossa. Tavoitteena on muodostaa näkemys Mikro-ORC energiamuuntimen mahdollisuuksista ja reunaehdoista osana työkoneluokan (150 kW… 400 kW) dieselmoottorikokonaisuutta, erityisesti maataloussektorilla. Työssä tarkasteltaviksi moottoreiksi valittiin kaksi eri AGCO Sisu Powerin dieselmoottoria. Laskennat suoritettiin moottorin valmistajan antamien hukkalämpövirtojen arvojen perusteella. Laskennan perusperiaatteena oli tutkia ORC-prosessin tuottamaa lisäsähkötehoa hyödyntämällä pakokaasujen lämpöenergiaa korkea-, keski- ja matalalämpötiloissa. Työssä vertailtiin kahden eri kiertoaineen prosessihyötysuhdetta, saatava sähkötehoa sekä prosessin sisäisiä parametreja. Lisäksi työssä tutkittiin ORC-prosessin laskentaa suunnittelupisteessä (design) ja suunnittelupisteen ulkopuolella (off-design), prosessisuureiden optimointia ja lämmönsiirtimien mitoitusta. Diplomityössä tarkasteltiin moottorin energiataseen mukaisten arvojen lisäksi moottorin parametrien muuttamisen vaikutusta hukkalämpövirroista saatavan tehoon. Työssä saatiin arvokasta tietoa polttomoottoreiden hukkalämpövirtojen muuntamisesta sähköksi ORC:lla sekä moottorin energiatehokkuuden parantamisesta.

2.6 MW:n tuulivoimakonvertterin nestejäähdytysjärjestelmän komponentit ja hinnat

Tässä tutkimuksessa selvitettiin nestejäähdytteisen 2.6 MW:n tuulivoimakonvertterin jäähdytysjärjestelmään kuuluvat komponentit ja niiden hinnat. Tällä pyritään helpottamaan uutta teknologiaa hyödyntävien jäähdytysjärjestelmien kehittäjiä kaupallistamaan tuotteensa selvittämällä heille nykyisten jäähdytysjärjestelmien hintaluokka. Työ tehtiin kirjallisuuskatsauksena ja lähteinä käytettiin pääasiassa ABB:lta saatavia julkisia materiaaleja. Komponenttien hinnat haettiin internetin hakukoneiden avulla, sekä lähettämällä tarjouspyyntöjä myyjille, jotka eivät hintojaan olleet suoraan ilmoittaneet. Hinnat komponenteista kerättiin 1, 10, 50 ja 100 kappaleen toimituserille, jolloin voitiin vertailla myös kuinka paljon edullisemmaksi sarjatuotanto tulisi, kuin yksittäisen tuotteen valmistaminen. Tuloksista huomattiin, että konvertterikaapiston sisäiset jäähdytysjärjestelmään kuuluvat komponentit muodostavat vain pienen osan siitä hinnasta, mikä aiheutuu ulkopuolisesta jäähdytysyksiköstä, johon kaapisto on kytkettävä. Käytettäessä yksittäistä jäähdytysyksikköä on koko jäähdytysjärjestelmän hinta 14-15 000 €, josta ulkoisen jäähdytysyksikön osuus on 12 000 €, eli yli 80 % kokonaishinnasta. Sarjatuotannossa hinta putoaa etenkin jäähdytysyksikön osalta huomattavasti. Uusia teknologioita kaupallistettaessa on niiden kokonaisuudessaan oltava tätä summaa halvempia, johon paras tapa päästä on keskittää huomionsa ulkoisen jäähdytysyksikön kustannusten laskemiseen. Toinen vaihtoehto kaupalliseen menestykseen, on tehdä samanhintainen jäähdytysjärjestelmä, mutta jäähdytysteholtaan huomattavasti tehokkaampi, sekä kooltaan pienempi.

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.

Repository content - lost in Discovery?

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Elasticsearch as a new search engine for Invenio and more

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Tag Cloud of Search Queries for Repository System

Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

A pulsatile flow model for in vitro quantitative evaluation of prosthetic valve regurgitation

A pulsatile pressure-flow model was developed for in vitro quantitative color Doppler flow mapping studies of valvular regurgitation. The flow through the system was generated by a piston which was driven by stepper motors controlled by a computer. The piston was connected to acrylic chambers designed to simulate "ventricular" and "atrial" heart chambers. Inside the "ventricular" chamber, a prosthetic heart valve was placed at the inflow connection with the "atrial" chamber while another prosthetic valve was positioned at the outflow connection with flexible tubes, elastic balloons and a reservoir arranged to mimic the peripheral circulation. The flow model was filled with a 0.25% corn starch/water suspension to improve Doppler imaging. A continuous flow pump transferred the liquid from the peripheral reservoir to another one connected to the "atrial" chamber. The dimensions of the flow model were designed to permit adequate imaging by Doppler echocardiography. Acoustic windows allowed placement of transducers distal and perpendicular to the valves, so that the ultrasound beam could be positioned parallel to the valvular flow. Strain-gauge and electromagnetic transducers were used for measurements of pressure and flow in different segments of the system. The flow model was also designed to fit different sizes and types of prosthetic valves. This pulsatile flow model was able to generate pressure and flow in the physiological human range, with independent adjustment of pulse duration and rate as well as of stroke volume. This model mimics flow profiles observed in patients with regurgitant prosthetic valves.