Efectos Visuales de las Aceleraciones Positivas Simulados por Ordenador

El artículo describe la simulación por ordenador digital de los efectos visuales en el organismo humano sometido a aceleraciones prositivas en sentido craneocaudal. Los resultados obtenidos posibilitan la utilización de un método complementario para la evaluación de la tolerancia a las aceleraciones positivas.

Simuloinnin hyödyntäminen ajoneuvon kestoikäanalyysissä

Diplomityö tehtiin Patria Land & Armament Oy:n toimeksiannosta. Patria Land & Armament Oy:n tuotteisiin kuuluvat vaativiin maasto-olosuhteisiin soveltuvat sotilasajoneuvot. Tuotesuunnittelussa otetaan huomioon ajoneuvon koko elinkaari, joten väsymismitoitus ja kestoikäanalyysit ovat suunnittelun tärkeitä osa-alueita. Kestoikäanalyysit ovat perinteisesti pohjautuneet mittausten avulla määritettyyn jännityshistoriaan. Työn tavoitteena oli tutkia tietokonesimuloinnin soveltuvuutta maastoajoneuvon jännityshistorian määrittämiseen. Selvityksen perusteella muodostettiin kohdeyrityksen tarpeisiin soveltuva ja kestoikäanalyysiä helpottava simulointiympäristö. Tietokonesimuloinnin tuloksien tarkkuutta tutkittiin mittaamalla todellisen ajoneuvon käyttäytymistä. Simulointiympäristö toteutettiin analysoimalla joustavia kappaleita ADAMS dynamiikkaohjelmistolla. Kappaleiden joustavuus mallinnettiin kelluvan koordinaatiston menetelmällä ja siihen käytettiin PATRAN/NASTRAN elementtimenetelmäohjelmistoa. Simulointiympäristön toimivuus testattiin case-esimerkin avulla. Esimerkissä tutkittiin AMV:n alatukivarren rasituksia. Tuloksista havaittiin, että simuloimalla on mahdollista tuottaa maastoajoneuvon rakenteiden jännityshistoria. Eri parametrien tutkiminen onnistuu vaivattomasti, mutta simuloimalla määritetyn kestoiän absoluuttisiin arvoihin tulee suhtautua varauksella.

Error Modeling and Accuracy Analysis of a Novel Mobile Hybrid Parallel Robot

Over the last decades, calibration techniques have been widely used to improve the accuracy of robots and machine tools since they only involve software modification instead of changing the design and manufacture of the hardware. Traditionally, there are four steps are required for a calibration, i.e. error modeling, measurement, parameter identification and compensation. The objective of this thesis is to propose a method for the kinematics analysis and error modeling of a newly developed hybrid redundant robot IWR (Intersector Welding Robot), which possesses ten degrees of freedom (DOF) where 6-DOF in parallel and additional 4-DOF in serial. In this article, the problem of kinematics modeling and error modeling of the proposed IWR robot are discussed. Based on the vector arithmetic method, the kinematics model and the sensitivity model of the end-effector subject to the structure parameters is derived and analyzed. The relations between the pose (position and orientation) accuracy and manufacturing tolerances, actuation errors, and connection errors are formulated. Computer simulation is performed to examine the validity and effectiveness of the proposed method.

Uma perspectiva computacional sobre catálise enzimática

Enzymes are extremely efficient catalysts. Here, part of the mechanisms proposed to explain this catalytic power will be compared to quantitative experimental results and computer simulations. Influence of the enzymatic environment over species along the reaction coordinate will be analysed. Concepts of transition state stabilisation and reactant destabilisation will be confronted. Divided site model and near-attack conformation hypotheses will also be discussed. Molecular interactions such as covalent catalysis, general acid-base catalysis, electrostatics, entropic effects, steric hindrance, quantum and dynamical effects will also be analysed as sources of catalysis. Reaction mechanisms, in particular that catalysed by protein tyrosine phosphatases, illustrate the concepts.

Algorismes de shading moderns|h[Recurs electrònic] :|b implementació i comparativa

Elmercat de jocs i de pel•lícules d'entreteniment demana constantment entornsmés realistes i efectes que sorprenguin a l'espectador.Els gràfics 3D interactius (per exemple, dels jocs) han vist una evoluciósorprenent en les dues últimes dècades. Hem passat de representacions moltesquemàtiques i simplificades dels entorns, a una qualitat visual que aviatserà indistingible de la realitat. El projecte tracta de desenvolupar un motor 3D des de zero. Es podria haver utilitzatun motor 3D ja disponible com a base, com per exemple el popular Unity,però s’ha decidit crear-lo ja que això dóna l’ oportunitat de conèixer com funcionen els motoscomercials i provar noves idees. En resum, és un treball difícil, però moltenriquidor, la qual cosa comporta una gran motivacio.S’han utilitzat noves tecnologies. No només s’ha volgut desenvoluparun motor 3D des de zero, si no que s’han volgut provar noves llibreries gràfiques i nous formats de dades 3d. El mercat té força oferta de les duess, per la qualcosa s’ha aprofitat l’ oportunitat per aprendre duess tecnologies noves.El procés de desenvolupar un projecte utilitzant tecnologies desconegudes permetrà aprendre els seus punts forts i febles, podent fer-neuna anàlisi crítica, que d'altra manera no es tindria.Finalment, s’ha implementat i comparat quatre algorismes de shading.La selecció dels quatre algorismes ha estat en base a les diferentsnecessitats que intenten cobrir. El primer, el Forward Shading, és l'algorismeclàssic, utilitzat des de fa dècades, però que teòricament escala malament respecte a la quantitat de llums. El segon, el Deferred Shading, teòricament,escala molt bé amb moltes llums, però té un cost base elevat, i un consum altde memòria. El tercer, el Deferred Lighting, és una variació de l'anterior queintenta reduir el cost base i l'úss de memòria. L'últim, el Inferred Lighting,intenta explotar la baixa freqüència de la il•luminació dels entorns 3D, persuportar una gran quantitat de llums amb un molt bon rendiment.Un cop implementats aquests quatre algorismes, s’han pogut compararrespecte el seu ús de la GPU, i el seu comportament en diferents tipusd'escenes, per tal de tenir una visió global de quin algorisme és adequat encada situació

Visualització en temps real de múltiples llums amb la tècnica de Lightcuts

Un bon sistema d’il.luminació juga un paper molt important per tal que els videojocs siguin realistes i atractius per a l’usuari. El projecte intenta optimitzar el sistema d’il.luminació de manera que la càrrega que representa per al sistema sigui inferior, sense haver de renunciar a la qualitat que tindríem sense fer servir aquest sistema. Amb dos objectius molt concrets: entendre i implementar l’algoritme de lightcuts i aconseguir una optimització en una escena utilitzant aquest algoritme

Models and applications for risk assessment and prediction of Asian soybean rust epidemics

Asian rust of soybean [Glycine max (L.) Merril] is one of the most important fungal diseases of this crop worldwide. The recent introduction of Phakopsora pachyrhizi Syd. & P. Syd in the Americas represents a major threat to soybean production in the main growing regions, and significant losses have already been reported. P. pachyrhizi is extremely aggressive under favorable weather conditions, causing rapid plant defoliation. Epidemiological studies, under both controlled and natural environmental conditions, have been done for several decades with the aim of elucidating factors that affect the disease cycle as a basis for disease modeling. The recent spread of Asian soybean rust to major production regions in the world has promoted new development, testing and application of mathematical models to assess the risk and predict the disease. These efforts have included the integration of new data, epidemiological knowledge, statistical methods, and advances in computer simulation to develop models and systems with different spatial and temporal scales, objectives and audience. In this review, we present a comprehensive discussion on the models and systems that have been tested to predict and assess the risk of Asian soybean rust. Limitations, uncertainties and challenges for modelers are also discussed.

Improving the calculation of rate of stratification in APROS

APROS (Advanced Process Simulation Environment) is a computer simulation program developed to simulate thermal hydraulic processes in nuclear and conventional power plants. Earlier research at VTT Technological Research Centre of Finland had found the current version of APROS to produce inaccurate simulation results for a certain case of loop seal clearing. The objective of this Master’s thesis is to find and implement an alternative method for calculating the rate of stratification in APROS, which was found to be the reason for the inaccuracies. Brief literature study was performed and a promising candidate for the new method was found. The new method was implemented into APROS and tested against experiments and simulations from two test facilities and the current version of APROS. Simulation results with the new version were partially conflicting; in some cases the new method was more accurate than the current version, in some the current method was better. Overall, the new method can be assessed as an improvement.

The Use of Radiostereometric Analysis in Fractures of the Distal Radius: From Phantom Models to Clinical Application

Radiostereometric analysis (RSA) is a highly accurate method for the measurement of in vivo micromotion of orthopaedic implants. Validation of the RSA method is a prerequisite for performing clinical RSA studies. Only a limited number of studies have utilised the RSA method in the evaluation of migration and inducible micromotion during fracture healing. Volar plate fixation of distal radial fractures has increased in popularity. There is still very little prospective randomised evidence supporting the use of these implants over other treatments. The aim of this study was to investigate the precision, accuracy, and feasibility of using RSA in the evaluation of healing in distal radius fractures treated with a volar fixed-angle plate. A physical phantom model was used to validate the RSA method for simple distal radius fractures. A computer simulation model was then used to validate the RSA method for more complex interfragmentary motion in intra-articular fractures. A separate pre-clinical investigation was performed in order to evaluate the possibility of using novel resorbable markers for RSA. Based on the validation studies, a prospective RSA cohort study of fifteen patients with plated AO type-C distal radius fractures with a 1-year follow-up was performed. RSA was shown to be highly accurate and precise in the measurement of fracture micromotion using both physical and computer simulated models of distal radius fractures. Resorbable RSA markers demonstrated potential for use in RSA. The RSA method was found to have a high clinical precision. The fractures underwent significant translational and rotational migration during the first two weeks after surgery, but not thereafter. Maximal grip caused significant translational and rotational interfragmentary micromotion. This inducible micromotion was detectable up to eighteen weeks, even after the achievement of radiographic union. The application of RSA in the measurement of fracture fragment migration and inducible interfragmentary micromotion in AO type-C distal radius fractures is feasible but technically demanding. RSA may be a unique tool in defining the progress of fracture union.

The development and evaluation of a distance learning system in ophthalmology

INTRODUCTION: Web-based e-learning is a teaching tool increasingly used in many medical schools and specialist fields, including ophthalmology. AIMS: this pilot study aimed to develop internet-based course-based clinical cases and to evaluate the effectiveness of this method within a graduate medical education group. METHODS: this was an interventional randomized study. First, a website was built using a distance learning platform. Sixteen first-year ophthalmology residents were then divided into two randomized groups: one experimental group, which was submitted to the intervention (use of the e-learning site) and another control group, which was not submitted to the intervention. The students answered a printed clinical case and their scores were compared. RESULTS: there was no statistically significant difference between the groups. CONCLUSION: We were able to successfully develop the e-learning site and the respective clinical cases. Despite the fact that there was no statistically significant difference between the access and the non access group, the study was a pioneer in our department, since a clinical case online program had never previously been developed.

Computational modeling for irrigated agriculture planning. Part I: general description and linear programming

Linear programming models are effective tools to support initial or periodic planning of agricultural enterprises, requiring, however, technical coefficients that can be determined using computer simulation models. This paper, presented in two parts, deals with the development, application and tests of a methodology and of a computational modeling tool to support planning of irrigated agriculture activities. Part I aimed at the development and application, including sensitivity analysis, of a multiyear linear programming model to optimize the financial return and water use, at farm level for Jaíba irrigation scheme, Minas Gerais State, Brazil, using data on crop irrigation requirement and yield, obtained from previous simulation with MCID model. The linear programming model outputted a crop pattern to which a maximum total net present value of R$ 372,723.00 for the four years period, was obtained. Constraints on monthly water availability, labor, land and production were critical in the optimal solution. In relation to the water use optimization, it was verified that an expressive reductions on the irrigation requirements may be achieved by small reductions on the maximum total net present value.

Electrically driven fertilizer applicator controlled by fuzzy logic

The present study shows the development, simulation and actual implementation of a closed-loop controller based on fuzzy logic that is able to regulate and standardize the mass flow of a helical fertilizer applicator. The control algorithm was developed using MATLAB's Fuzzy Logic Toolbox. Both open and closed-loop simulations of the controller were performed in MATLAB's Simulink environment. The instantaneous deviation of the mass flow from the set point (SP), its derivative, the equipment´s translation velocity and acceleration were all used as input signals for the controller, whereas the voltage of the applicator's DC electric motor (DCEM) was driven by the controller as output signal. Calibration and validation of the rules and membership functions of the fuzzy logic were accomplished in the computer simulation phase, taking into account the system's response to SP changes. The mass flow variation coefficient, measured in experimental tests, ranged from 6.32 to 13.18%. The steady state error fell between -0.72 and 0.13g s-1 and the recorded average rise time of the system was 0.38 s. The implemented controller was able to both damp the oscillations in mass flow that are characteristic of helical fertilizer applicators, and to effectively respond to SP variations.

Flexible multibody approach in bone strain estimation during physical activity:

Bone strain plays a major role as the activation signal for the bone (re)modeling process, which is vital for keeping bones healthy. Maintaining high bone mineral density reduces the chances of fracture in the event of an accident. Numerous studies have shown that bones can be strengthened with physical exercise. Several hypotheses have asserted that a stronger osteogenic (bone producing) effect results from dynamic exercise than from static exercise. These previous studies are based on short-term empirical research, which provide the motivation for justifying the experimental results with a solid mathematical background. The computer simulation techniques utilized in this work allow for non-invasive bone strain estimation during physical activity at any bone site within the human skeleton. All models presented in the study are threedimensional and actuated by muscle models to replicate the real conditions accurately. The objective of this work is to determine and present loading-induced bone strain values resulting from physical activity. It includes a comparison of strain resulting from four different gym exercises (knee flexion, knee extension, leg press, and squat) and walking, with the results reported for walking and jogging obtained from in-vivo measurements described in the literature. The objective is realized primarily by carrying out flexible multibody dynamics computer simulations. The dissertation combines the knowledge of finite element analysis and multibody simulations with experimental data and information available from medical field literature. Measured subject-specific motion data was coupled with forward dynamics simulation to provide natural skeletal movement. Bone geometries were defined using a reverse engineering approach based on medical imaging techniques. Both computed tomography and magnetic resonance imaging were utilized to explore modeling differences. The predicted tibia bone strains during walking show good agreement with invivo studies found in the literature. Strain measurements were not available for gym exercises; therefore, the strain results could not be validated. However, the values seem reasonable when compared to available walking and running invivo strain measurements. The results can be used for exercise equipment design aimed at strengthening the bones as well as the muscles during workout. Clinical applications in post fracture recovery exercising programs could also be the target. In addition, the methodology introduced in this study, can be applied to investigate the effect of weightlessness on astronauts, who often suffer bone loss after long time spent in the outer space.

Pyörivän keskiökärjen rakenteen kehittäminen työstövärähtelyjen välttämiseksi sorvauksessa

Tässä diplomityössä käsitellään sorvauksen työstövärähtelyjen ja sorvin keskiökärjen rakenteen yhteyttä. Työ on osa Lappeenrannan teknillisen yliopiston VMAX-projektia, ja sen taustalla on pyrkimys uudenlaisen, sorvin kärkipylkän puristusvoiman ajonaikaiseen säätämiseen perustuvan työstövärähtelyjen välttämismenetelmän kehittämiseen. Tämän menetelmän toiminnan todentaminen oli työn ensimmäinen tavoite. Menetelmän toteuttaminen asettaa kuitenkin käytetyn keskiökärjen rakenteelle tiettyjä vaatimuksia. Työn toisena tavoitteena oli nämä vaatimukset täyttävän keskiökärjen prototyypin kehittäminen. Tutkimus eteni seuraavasti. Ensimmäiseksi ongelma määriteltiin tutustumalla työn teoreettiseen taustaan ja aiheeseen liittyvään tutkimukseen Lappeenrannan teknillisestä yliopistosta ja muualta. Myös keskiökärkiä valmistavien yritysten tuotekatalogeja tarkasteltiin. Seuraavaksi siirryttiin alustavaan suunnitteluvaiheeseen, jossa verifioitiin menetelmän toiminta ja luotiin konsepteja keskiökärjen rakenteen kehittämistä varten. Tämän alustavan vaiheen jälkeen suoritettiin suunnitteluprosessi keskiökärjen prototyypille. Lopuksi, suunnitellun prototyypin rakenteen käyttäytymistä arvioitiin tietokonemallinnuksen avulla. Lisätuloksena tutkimuksen aikana johdettiin yksinkertaistettu elementtimenetelmään perustuva laskentamalli järjestelmän ominaistaajuuksien selvittämiseksi. Laskentamallin tarkkuutta arvoitiin. Suunnitteluprosessin tuloksena saatiin kaikki menetelmän toiminnan sekä normaalin käytön asettamat vaatimukset täyttävä rakenne keskiökärjen prototyypille. Myös johdetun laskentamallin tulokset ovat varsin lähellä 3D-elementtimallinnuksen antamia tuloksia. Tutkimuksen tavoitteiden voidaan siis sanoa toteutuneen. Koska prototyyppiä ja laskentamallia ei kuitenkaan ole vielä kokeellisesti verifioitu, tämä ei ole täysin varmaa.

Nursing Students’ Learning about an Empowering Discourse In Patient Education

The main purpose of this study was to describe and evaluate nursing students' learning about an empowering discourse in patient education. In Phase 1, the purpose was to describe an empowering discourse between a nurse and a patient. In Phase 2, the purpose was first to create a computer simulation program of an empowering discourse based on the description, and second, the purpose was to evaluate nursing students’ learning of how to conduct an empowering discourse using a computer simulation program. The ultimate goal was to strengthen the knowledge basis on empowering discourse and to develop nursing students’ knowledge about how to conduct an empowering discourse for the development of patient education. In Phase I, empowering discourse was described using a systematic literature review with a metasummary technique (n=15). Data were collected covering a period from January 1995 to October 2005. In Phase 2, the computer simulation program of empowering discourse was created based the description in 2006–2007. A descriptive comparative design was used to evaluate students’ (n=69) process of learning empowering discourse using the computer simulation program and a pretest–post-test design without a control group was used to evaluate students’ (n=43) outcomes of learning. Data were collected in 2007. Empowering discourse was a structured process and it was possible to simulate and learned with the computer simulation program. According to students’ knowledge, empowering discourse was an unstructured process. Process of learning empowering discourse using the computer simulation program was controlled by the students and it changed students’ knowledge. The outcomes of learning empowering discourse appeared as changes of students’ knowledge to more holistic and better-organized or only to more holistic or better-organized. The study strengthened knowledge base of empowering discourse and developed students to more knowledgeable in empowering discourse.