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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Estimation of Radial Runout

Nilsson, Martin January 2007 (has links)
The demands for ride comfort quality in today's long haulage trucks are constantly growing. A part of the ride comfort problems are represented by internal vibrations caused by rotating mechanical parts. This thesis work focus on the vibrations generated from radial runout on the wheels. These long haulage trucks travel long distances on smooth highways, with a constant speed of 90 km/h resulting in a 7 Hz oscillation. This frequency creates vibrations in the cab, which can be found annoying. To help out with the vibration diagnosis when a truck enters a mechanical workshop, this work studies methods for radial runout detection using the wheel speed sensors. The main idea is to represent the varying radius signal with a sinusoid, where the calculations are based on Fourier series. The estimated radial runout value is then the amplitude of the sinusoid. In addition to the detection part, the work also present results regarding how the relative phase difference between two wheels with radial runout effects the lateral motion of the cab. This thesis work was performed at Scania CV AB in Södertälje, Sweden and all measurements have been full scale experiments on real trucks.
32

Šiluminės aplinkos traktorių kabinose tyrimas šaltuoju metų laikotarpiu / Investigation on thermal environment of tractor cabs during the cold season of the year

Jatulis, Aivaras 02 June 2011 (has links)
Problemos aktualumas. Dabar beveik visi žemės ūkio darbai dirbami mobilios technikos pagalba. Netinkama traktoriaus kabinos šiluminė aplinka mažina darbo našumą, kokybę, iškyla galima rizika dėl sveikatos sutrikimo, pablogėjimo. Darbo tikslas. Išanalizuoti nuo ko priklauso šiluminė aplinka traktoriaus kabinoje, ištirti ir palyginti trijų skirtingų traktorių amžiaus ir markės šiluminės aplinkos parametrus su normuojamomis bei palyginti tarpusavyje ir pasiūlyti priemones šiluminei aplinkai traktorių kabinose gerinti. Tyrimai atlikti traktoriuose ,,John Deere 6330“ (2008 m.), ,,MTZ-820“ (1994 m.) ir ,,T-16M“ (1974 m.) kabinose. Gauta, kad oro judėjimo greičiai traktorių kabinose buvo iki 0,1 m/s, o leistinas yra iki 0,3 m/s. Pakankama šiluminės aplinkos oro temperatūra 17°C traktoriaus ,,John Deere 6330“ kabinoje buvo po 53 min., traktoriaus ,,MTZ-820“ kabinoje maksimali temperatūra buvo 13,5°C, o traktoriaus ,,T-16M“ kabinoje maksimali temperatūra buvo 10,6°C. Santykinis oro drėgnis viršijo pakankamos šiluminės aplinkos vertę iki 75% visuose traktoriuose. Traktoriaus ,,John Deere 6330“ kabinos priekinės sienelės atitvaros temperatūra siekė 22,26°C ir buvo 2,29 kartus didesnė negu traktoriaus ,,MTZ-820“ bei 31,8 kartus didesnė negu traktoriaus ,,T-16M“. Metalinę atitvarą iš kabinos vidaus pusės padengus veltiniu, šilumos srauto tankis per atitvarą į aplinką sumažėtų nuo 74,82 W/m2 iki 0,14 W/m2. / Problem. Now almost all the agricultural work performed in support of mobile equipment. Inappropriate tractor thermal environment reduces the productivity, quality and there is a potential risk for health problems, deterioration. Objective. To analyze the thermal environment depends on what the tractor's cab, to investigate and compare the three tractors of different ages and grades of thermal environmental parameters and compared with the regulated one another and to propose measures to the thermal environment of tractor cabs to improve. Investigations were carried out for tractors ,,John Deere 6330” (2008), ,,MTZ-820” (1994) and ,,T-16M” (1974) booths. Try the air speed of tractor cabs were up to 0,1 m/s and an allowance of up to 0,3 m/s. Sufficient heat the ambient air temperature of 17°C, a tractor ,,John Deere 6330” cab was after 53 minutes. Tractor ,,MTZ-820” deck the maximum temperature was 13,5°C and the tractor ,,T-16M” deck the maximum temperature was 10,6°C. Relative humidity above a sufficient amount of thermal environment by up to 75% on all tractors. Tractor ,,John Deere 6330” cab front wall of the envelope temperature was 22,26°C was 2,29 times higher than the tractor ,,MTZ-820“ and 31,8 times higher than the tractor ,,T-16M”. Metal guard from inside the cab sides felt coating, heat flux density through the guard into the environment would be reduced from74,82 W/m2 to 0,14 W/m2.
33

Aplicativo de Taxi Colectivo "Habla, Vas" / Carpooling App “Habla, Vas”

Cárdenas Gamboa, Karol Ivette, Diestra Loayza, Diego Paolo, Falcon Romani, Dics Macs, Hidalgo Remigio, Kelly Gianela 15 July 2020 (has links)
El proyecto que presentamos en este trabajo, al cual decidimos llamar "Habla, Vas", consiste en un sistema de conexión mediante información relevante de demanda y oferta entre personas que necesiten movilizarse en un taxi colectivo a través de las principales rutas de la ciudad y colectiveros que necesiten generar mayores ingresos en estas rutas con mayor afluencia de tráfico en Lima. La idea de negocio parte de la necesidad de los autores por movilizarnos rápido, seguro y fácil por la ciudad, sin utilizar medios de transporte públicos que hacen que la experiencia de viajar sea incómoda, por la alta demanda del servicio y poca oferta. Esta situación, que se presenta a diario en miles de limeños, puede ser solucionado mediante una aplicación que simplifique el proceso de intercambio de información y nos evite caer en situaciones incómodas a las que los taxis colectivos tradicionales nos exponen. Asimismo, luego de la evaluación financiera preliminar del proyecto, notamos que el mismo tiene un potencial de rentabilidad altamente explotable, que constituye una oportunidad inmejorable para ser los primeros en este segmento, logrando lo que en su momento consiguió empresas como Uber o Globo. Además, se requiere una inversión relativamente pequeña frente a un negocio convencional y será totalmente accesible a través de las tiendas de Android y Apple. Finalmente, este proyecto será nuestra mejor carta de presentación e ingreso en el mundo de los negocios para nuestros futuros proyectos, ya que hemos recabado la información necesaria para entender la operación de ellos. / The project that we present in this document, which we decided to call "Habla, Vas", consists of a connection system through relevant information of demand and supply, between people who need to move in a group through the main routes of the city and groups who need to generate income on these routes with the highest traffic flow in Lima. The business idea stems from the authors' need to move quickly, safely and easily around the city, without using public means of transport that make traveling uncomfortable, due to the high demand for the service and low supply. This situation, which occurs daily in thousands of Lima, can be solved through by the application that simplifies the process of information exchange and prevents us from falling into uncomfortable situations to which traditional groups expose us. Likewise, after the preliminary financial evaluation of the project, we note that it has a highly exploitable profitability potential, which constitutes an unbeatable opportunity to be the first in the segment, achieving what companies such as Uber or Globo achieved at the time. Also, a relatively small investment is required compared to a conventional business and will be fully accessible through Android and Apple stores. Finally, this project will be our best letter of introduction and entry into the business world for our future projects, since we have collected the necessary information to understand their operation. / Trabajo de investigación
34

Optic Fiber Communication in Commercial Vehicles : Testing of mechanical rigidity

Venugopal Parasuraman, Vijay Adhithyan January 2022 (has links)
The backbone of this dissertation is a discussion of the adaptability of optical fiber modes of transmission. The technological boom in commercial vehicles tends to include more electronic components and more data flow. The traditional copper transmission is reliable but has drawbacks. At present optical fiber, technology is in huge demand in fields like avionics, medicine, and communication across continents. The drastic shift to fiber was due to the enormous increase in capacity. Simultaneously the commercial vehicle sector is advancing in the direction of sensors that require a non-disruptive data flow. Furthermore, autonomous driving technology pushes the transition from copper to optic fiber. One expects optical fiber to supplant the traditional copper cables in the future. The dispersion and scattering losses need to be studied as well as the difference in cost.
35

A Multibody Dynamics Approach to the Modeling of Friction Wedge Elements for Frieght Train Suspensions

Steets, Jennifer Maria 07 June 2007 (has links)
This thesis presents a theoretical application of multibody dynamics with unilateral contact to model the interaction of the damping element in a freight train suspension, the friction wedge, with the bolster and the side frame. The objective of the proposed approach is to produce a stand-alone model that can better characterize the interaction between the bolster, the friction wedge, and the side frame subsystems. The new model allows the wedge four degrees of freedom: vertical displacement, longitudinal (between the bolster and the side frame) displacement, pitch (rotation about the lateral axis), and yaw (rotation about the vertical axis). The new model also allows for toe variation. The stand-alone model shows the capability of capturing dynamics of the wedge which were not possible to simulate using previous models. The inclusion of unilateral contact conditions is integral in quantifying the behavior during lift-off and the stick-slip phenomena. The resulting friction wedge model is a 3D, dynamic, stand-alone model of a bolster-friction wedge-side frame assembly. The new stand-alone model was validated through simulation using simple inputs. The dedicated train modeling software NUCARS® has been used to run simulations with similar inputs and to compare — when possible — the results with those obtained from the new stand-alone MATLAB friction wedge model. The stand-alone model shows improvement in capturing the transient dynamics of the wedge better. Also, it can predict not only normal forces going into the side frame and bolster, but also the associated moments. Significant simulation results are presented and the main differences between the current NUCARS® models and the new stand-alone MATLAB models are highlighted. / Master of Science
36

Vibration Modeling and Experimental Analysis of a Locomotive Cab

Venezia, James J. Jr. 01 May 1997 (has links)
This study evaluates noise and vibrations in a heavy freight locomotive cab, and provides several measures for providing more comfort to the crew. A full-scale production cab and sill structure is used to provide the results. The cab is setup in a controlled laboratory environment in a manner similar to the installation on a locomotive. Field measurements are used to emulate actual vibration input to the cab structure. A 16-channel data acquisition system is used to collect both noise and vibration data on various parts of the cab structure and inside the cab. Upon establishing the baseline for laboratory vibration measurements and correlating them with field data, a design of experiment was conducted to evaluate the vibration contribution of various parts of the cab. This showed that the cab floor and cab roof had the largest vibrations. A series of solutions including stiffening the cab floor and damping the cab roof were investigated. The results showed that although such solutions reduce localized vibrations, the overall effect on reducing cab interior noise is minimal. As a more global solution, the cab was isolated from the sill structure through six elastomeric elements mounted at the base of the cab and at the crash post. The mounts at the base were selected such that they support the static weight of the cab, provide a resonance frequency that is below the excitation range, and offer good lateral and longitudinal stability. Two tube-form elastomeric mounts were placed between the cab structure and the crash posts which attach to the front of the sill structure. The test results showed that the soft-mounted cab had significantly lower noise and vibration than the original cab. The vibration levels were reduced 10 to 100 times at certain locations and frequency ranges. The overall noise level was reduced by approximately 6 dBA. In an attempt to provide an estimate of effectiveness of the mounts with different stiffness values, a simulation model was prepared in Matlab. Although the model did not yield accurate results, it resulted in several recommendations for future research work. / Master of Science
37

Advanced Multibody Dynamics Modeling of the Freight Train Truck System

Ballew, Brent Steven 05 June 2008 (has links)
Previous work in the Railway Technology Laboratory at Virginia Tech focused on better capturing the dynamics of the friction wedge, modeled as a 3D rigid body. The current study extends that work to a half-truck model treated as an application of multibody dynamics with unilateral contact to model the friction wedge interactions with the bolster and the sideframe. The half-truck model created in MATLAB is a 3D, dynamic, multibody dynamics model comprised of four rigid bodies: a bolster, two friction wedges, and a sideframe assembly. The model allows each wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and sideframe), pitch (rotation around the lateral axis), and yaw (rotation around the vertical axis). The bolster and the sideframe have only the vertical degree of freedom. The geometry of these bodies can be adjusted for various simulation scenarios. The bolster can be initialized with a pre-defined yaw (rotation around the vertical axis) and the sideframe may be initialized with a pre-defined pitch/toe (rotation around the lateral axis). The multibody dynamics half-truck model simulation results have been compared with results from NUCARS®, an industry standard train modeling software, for similar inputs. The multibody dynamics models have also been extended to a variably damped full-truck model and a variably damped half-truck warping model. These models were reformulated to react dynamically to simulated truck warp inputs. The ability to better characterize truck warping properties can prevent train roll over and derailments from truck hunting. In a quarter-truck variably damped configuration the effects of a curved wedge surface has also been explored. Actual friction wedges have surfaces which are slightly curved, this iteration in the multibody dynamics friction wedge modeling attempts to draw one step closer to actual friction wedge geometry. This model lays the ground work for a contact dependant wedge wearing model based on material properties and tribology. / Master of Science
38

Hybride Prototypen im Design

Lorenz, Sebastian, Klemm, Maria, Krzywinski, Jens January 2016 (has links)
Aus der Einführung: "Die Verwendung von Prototypen besitzt eine zentrale Rolle bei der Produktentwicklung und im Designprozess (Camere et al. 2016). Wie Camere und Bordegoni feststellen hat sich der Fokus der Designdisziplin auf Funktionalität um die Aspekte der Usability und der User Experience erweitert. Damit einhergehend hat sich auch die Rolle der Prototypen von Funktionsmustern und Präsentationsobjekten um die Funktionen als Evaluierungs- und Versuchsobjekte ergänzt. Die Integration von Nutzern in den Designprozess ist dabei ein weiterer Punkt bei denen Prototypen ein wichtiges Werkzeug zur Kommunikation und kooperativen Arbeit liefert (Schneider 1996). Die Integration von Prototyping-Methoden in den unterschiedlichen Phasen des Designprozesses führt zu unterschiedlichen Anforderungen hinsichtlich der Form und Aufgabe der Prototypen. Entsprechend vielfältig sind die heute verwendeten Arten von Prototyping. ..."
39

Effekt av vonoprazan vid behandling av erosiv esofagit : Ett nytt syrahämmande läkemedel som hämmar protonpumpen / Effect of vonoprazan in the treatment of erosive esophagitis : A novel proton pump inhibitor for acid suppression

Al Ahdab, Moimnai January 2024 (has links)
Erosiv esofagit (EE) innebär uppkomst av inflammation och slemhinneskador i matstrupen. Den huvudsakliga orsaken till EE är gastroesofageal reflux (GERD), då det sura maginnehållet stöts upp i matstrupen. Bristande funktion av nedre esofagussfinktern (LES) och diafragmabråck kan också orsaka EE. Obehandlad EE kan leda till komplikationer såsom Barretts esofagus (BE), adenocarcinom, förträngning av matstrupen och gastrointestinala blödningar. Diagnostiken sker med hjälp av endoskopi. Behandlingen av EE går bland annat ut på att påskynda läkning av slemhinneskador i matstrupen. Den består huvudsakligen av läkemedelsterapi och livsstil- och kostförändringar, men även kirurgi kan vara en möjlig behandling. Läkemedelsterapi består av syrahämmande läkemedel som hämmar produktionen av magsyra. Protonpumpshämmare (PPI), till exempel lansoprazol (LPZ), är standardbehandlingen vid syrarelaterade sjukdomar, bland annat EE. PPI har dock begränsningar och upp till 20 % med svårare EE uppnår inte läkning. Vonoprazan (VPZ) tillhör kalium kompetitivasyrablockerare (P-CAB) och är ett nytt syrahämmande läkemedel som är godkänt i bland annat Japan och USA för behandling av EE. Syftet med detta litteraturarbete var att undersöka effekten av 20 mg VPZ jämfört med 30 mg LPZ efter åtta veckors behandling av EE, genom att ta del av publicerade kliniska studier. Fyra olika RCT-studier hämtade från databasen PubMed användes i detta litteraturarbete. Alla fyra studier resulterade i att VPZ inte var sämre än LPZ vid behandling av EE i upp till åtta veckor. Fler patienter i VPZ-gruppen uppnådde läkning av EE i samtliga studier. Dessutom visade VPZ ha bättre effekt hos patienter med svårare EE. Number Needed to Treat (NNT) för de olika studierna varierade mycket, därför kunde inte den användas för att beskriva den kliniska effekten av VPZ vid behandling av EE. Både VPZ och LPZ tolererades väl. Slutsatsen var att VPZ 20 mg en gång dagligen var inte sämre än LPZ 30 mg en gång dagligen vid behandling av EE i 8 veckor. VPZ var effektiv och visade bättre resultat än LPZ när det gäller EE-läkning. Detta gäller speciellt patienter med svårare EE. Båda läkemedlen tolererades väl.
40

Effektivisering av robotcell med avseende på cykeltid och framtida produktvariation / Robotic cell efficiency with respect to cycle time and future product variation

Salih, Sarbast, Al-Hamadany, Abdullah January 2018 (has links)
Detta projekt har utförts på monteringslinan i Volvo Construction Equipment (VCE), Hallsberg. Där har man en robotcell som arbetar i samspel med limstationerna 17&18. Utav 4 hyttfamiljer limmas och monteras glasrutor till 3 av hyttfamiljerna manuellt. Robotcellen limmar glasrutorna för 1 hyttfamilj som har 2 typer av hytter, med en cykeltid på 8,4–9,5 min. Då takttiden ligger på 7,5 min/hytt för resten av linan anses limstationerna vara en trång sektor enligt VCE. Med en ökad framtida produktvariation och ett ökat kundbehov anser VCE att den trånga sektorn har förutsättningarna för att bli en framtida flaskhals då takttiden ska ner till 7,2 min/hytt till år 2020. Med hjälp av Leanprinciper och Sex Sigma verktyg har projektutförarna avhandlat frågeställningen "Hur kan robotcellen effektiviseras med avseende på cykeltid och framtida produktvariation?". Genom en framtagning av en nulägesanalys med hjälp av tidmätningar, intervjuer och teoriinsamling kunde sedan en värdeflödeskarta skapas. Genom rotorsaksanalyser på icke-värdeskapande men nödvändiga aktiviteter kunde ett förbättringsförslag presenteras med en uppskattad cykeltid på mindre än 7–7,6 min. Detta med hjälp av en hanteringsrobot och en limrobot som har separata aktiviteter som är parallella, istället för att ha en robot som har samtliga aktiviteter som i nuläget. Projektutförarna rekommenderar att VCE för arbetet vidare genom att- ta reda på hur lång tid det tar för en automatiserad limning av glasrutor till samtliga hyttyper, - undersöka hur snabbt hanteringsroboten behöver arbeta i förhållande till limroboten för att tillfredsställa behovet av glasrutor för limroboten, - undersöka hur kasserade glasrutor från robotcellerna påverkar monteringsflödet samt - undersöka utvecklingsmöjligheter för att effektivisera den enda värdeskapande aktiviteten för limroboten med avseende på cykeltid. / This project has been carried out on the assembly line in Volvo Construction Equipment (VCE), Hallsberg. A robotic cell is located in the assembly line and works in conjunction with the glue stations 17 & 18. Out of 4 cab families, windows are glued and mounted to 3 of the cab families manually. The robotic cell glues the windows for 1 cab family that has 2 types of cabs, with a cycle time of 8.4-9.5 min. Since the takt time is 7.5 min/cab in the other sections of the assembly line, the glue stations are considered a narrow sector according to VCE. With increased future product variability and increased customer demand, VCE considers that the narrow sector has the prerequisites for becoming a future bottleneck, as the takt time will drop to 7.2 min/cab to 2020. With the help of Lean principles and Six Sigma tools, project executives have dealt with the question "How can the robotic cell be made more efficient with respect to cycle time and future product variability?”. Through a current state analysis by means of time measurements, interviews and theory collection, a value-flow chart could then be created. By root cause analysis on non-value-adding but necessary activities an improvement proposal could be presented with an estimated cycle time of less than 7-7.6 min. The thesis workers propose that VCE goes ahead by- finding out how long an automated gluing of windows take (for all cabs),- examining how fast the handling robot needs to work in relation to the glue robot (to satisfy the need for windows for the glue robot),- examining how discarded windows from the robotic cells affect the assembly flow, and- investigating the opportunities to streamline the only value-creating activity for the glue robot with regards to cycle time.

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