This bachelor thesis is about an ultrasonic sensor, implemented in a bubble chamber in Artis. The sensor consists of the piezoelectric sensor and an electronic control circuit. The control circuit consists of a programmable microprocessor, PIC18F2420 and a circuit, which sends the excitation signal to the piezoelectric sensor, and later receives the echo. This bachelor thesis consists also of a theoretical study, which examines different techniques of liquid level sensing in a chamber. The study discusses which factors are important in liquid level sensing and examine accepted methods.

The purpose of this study was to describe perceived psychosocial work environment and musculoskeletal complaints among baggage handlers, and to evaluate whether there is any linear relationship between them. The study is a questionnaire based cross-sectional study, and part of an ongoing larger project. Therefore, the number of forms has been limited to those that were collected in the project by 2010-11-25 (N=117). The questions analyzed in the study come from the Copenhagen Psychosocial Questionnaire and ?Nordiska Ministerrådets formulär om besvär i rörelseorganen?, respectively.

Each year, Heterobasidion spp. is a major cause of economic losses to forestry in the northernhemisphere, including Sweden. New results indicate that pre?commercial thinnings could be at riskfor Heterobasidion spp. infections.

The purpose of this study was to find out if motion movements, e.g. number of lying bouts and lying time with a registered activity monitoring sensor can detect an impending calving and thereby be used as a measure and an indicator for an upcoming calving. For this, automatically step sensors were used and were attached to one of the cows? hind leg. The sensor registered the individual step and movement activity of the cow.

Genom konstruktion och tillverkning av prototyper samt med hjälp av ljud- och flödesmätningar av dessa, tillsammans med standardmodellen, har vi lyckats förbättra flödet genom ventilen Al-db 450, producerad av Fresh AB i Gemla. För ljudmätningar har en testrigg konstruerats och tillverkats..

Kundrelationerna i svenska B2C-företag är inte lika goda som de var för 60 år sedan och de är inte lika goda som företagen skulle önska att de var. Forskningsfrågan och syftet med uppsatsen var därför att förklara vad som påverkar svenska B2C-företags beslut att utnyttja Radio Frequency Identification (RFID) som identifieringsteknik för att personliggöra kundrelationer inom sina lojalitetsprogram. Studien utfördes som en fallstudie då vi undersökte hur två stora svenska B2C-företag, IKEA Family och ICA, arbetade med lojalitetsprogram, identifieringstekniker och hur de ställde sig till alternativa identifieringstekniker gestaltat genom RFID. Studien utfördes med deduktiv ansats genom inledande teoriinsamling och därefter genom intervjuer med en intervjuperson på vardera företag. De slutsatser som sedermera kunde dras var att tillräcklig kunskap saknas kring RFID och dess potential, att det är en ekonomisk fråga och en stor investering för företag som inte brukar vara först att ta till sig ny teknik som dessutom inte är standardiserad samt att det skulle kunna kränka kundernas integritet och därmed ha motsatt effekt till lojalitetsprogrammens syfte..

The goal of this thesis work is to enable an existing UHF radar to operate in the VHF band instead. In order to achieve this, new coherent local oscillators are required. Different options are suggested and one of them is implemented and analyzed..

Comfort analyses regarding human induced vibrationsIt is not too common among civil engineers in Sweden to perform comfort analyses considering the vibrations caused by human activities. In addition, the Swedish standards lack requirements to be used for comfort analyses in design of floor-systems. The demand for large spans in combination with slender slabs, is today a reason to investigate the floor-system constructions, in order to prevent disturbing vibrations and oscillations.The purpose of this thesis is to create a guide for how a comfort analysis, considering vibrations, should be implemented. Göran Svedenbjörk who is an expert in structural dynamics has been interviewed where he presents his latest project Värtaterminalen and answers some questions about vibrations due to human activities.Floor-systems, consisting of concrete slabs supported by steel or concrete beams, have been investigated with simulations in the finite element program Abaqus. In the simulations, the influence of various factors on the natural frequency of floor-systems and the acceleration level caused by dynamic loads, is studied.

Hydroware Elevation Technology AB sells control and regulation equipment for hydraulic elevators. The company now wants to investigate the possibility of changing their present softstarters to Frequency inverters to supply power to their pump engines. They also want to investigate the possibility of future use in so called ?intelligent? houses.The purpose of this report is to investigate these possibilities..

This thesis examines and measures differences in effciency between L1- and L2 language use for solving referential problems. Quantitative measures used in the study were time and error frequency. Qualitative measures, such as how the tasks and the participants own performance were experienced, were measured by an post interview and two questionaires. Two different tasks, a sorting task and a construction task, in which each informant was given the role as a constructor or instructor, were used for data gathering. A total of 20 dyads, divided in two language groups (English and Swedish) participated in the study.

A power system will inevitably be subjected to transient overvoltages, most often produced by switching operations and lightning strikes. These transient overvoltages may harm sensitive equipment without sufficient protection, but it is not an easy task to predict what transients may occur or how they affect the system. A fault occurred in a low voltage system at Forsmark 2012 and overvoltages from lightning were concluded as the probable cause. The three aims with this thesis are to develop and test a model of the power system at Forsmark 3, analyse the transient behaviour of the system when subjected to lightning surges and identify critical parameters, and lastly to provide a tool for investigating the protection of the system. The modelling and simulations were performed in the freely available simulation program LT Spice.

For several years Uppsala University together with several companies has been involved in a WISENET project aimed at improving railway transport security. By placing a sensor system near the wheels of each wagon, the temperature of the bearings can be measured and transmitted to a collector placed centrally on the wagon. This in turn transmits the collected data to RFID receivers placed intermittently along the railway.As the signals are transmitted wirelessly, problems may occur as the antennas get dirty or coated with ice and snow. To determine the effects of these coatings, several tests were performed examining the reflection coefficient S11, the impedance Z11 and the efficiency eta of an antenna, and how they varied when various coatings were placed over the antenna. Examined coatings were ice, snow and water to determine the effects of weather, and various metal-based coatings: powdered iron both pure and partially oxidized, and iron ore granules.

Active headsets have been on the market for years and now it is time for something else to enter the stage. The technology of active noise reduction can for exmple also be used in ventilation systems for reducing ventilation noise. An active control system principally consists of four important components, namely the downstream error microphone, the upstream detection or reference microphone, the digital signal processor (DSP) and a loudspeaker. The upstream reference microphone listen to the primary ventilation noise and sends it to the DSP which makes a phase shift to the signal and sends it to the loudspeaker. The loudspeaker sends out the opposite waveform of the incoming one and reduce the primary ventilation noise.

Report of diploma work conducted at the Swedish Radiation Safety Authority (SSM) as part of the bachelors program in Nuclear Engineering at Uppsala University.All nuclear power plants in Sweden are obliged to report any deficiency in their barriers or the defense in depth in obedience to SSM?s regulations concerning safety in nuclear facilities. In addition, there is an international system for reporting such events. The purpose of this thesis is to study the Swedish report system and to analyze the differences between Swedish and international event reporting.In the Swedish system, SSM?s regulations are effectuated by means of event reports classified as category 1-3, designed individually at each Swedish facility.

This report summarize what have been done during the Master of Science Thesis that Klas Schjelderup has written for the company RANOTOR Utvecklings AB. The company is developing modern steam engines and this work should develop a machine to perform tests on a new type of piston seal that hopefully could be used in the future. The steam engines will be both volumetric and energy compact, around 1600hp/literof cylinder volume, and it will have a lot of practical applications.The new type of piston seal is hydrostatic lubricated which means that a fluid is separating two faces that normally is in contact. In this case pressurized water is used to separate the piston seal from the cylinder wall. RANOTOR have earlier formulated that at least the expander in the modern steam engine have to be oil-free, due to other components functionality in the closed water system.