Thesis (M.A. 1980) from the Department of Philosophy, University of Adelaide.

Univ., Diss.--Tel Aviv . / Includes bibliographical references and index.

[Abstract]: Sugarcane farmers in Bundaberg have had limited access to irrigation water over the last ten years. The district has the potential of growing 3.8 million tonnes of sugarcane. However, a series of dry seasons saw this reduce to 2.1 million tonnes in 2002. Compounding the effects of both dry seasons and limited water supplies has been a 30% reduction in the sugar price over this period. The irrigation requirement of sugarcane in the Bundaberg area is 8 ML/ha. The original allocated volume for sugarcane production in this area was 4.5 ML/ha (based on 1970 production areas). However, as the area under production has increased and announced allocations in each year has reduced, this allocation is now equivalent to an application volume of about 2 ML/ha A change from the traditional practice of full irrigation is required as water supplies become depleted. As there were no clear guidelines on how growers could respond to diminishing water supplies, this research investigated opportunities to fine tune irrigation practices and the performance of irrigation systems (ie. low cost solutions) that would assist growers to maximise sugarcane yield. A grower survey was initially conducted to identify current practice and opportunities for change. Field investigations focused on the performance of water winch and furrow irrigation systems, which make up 91% of the irrigated area in the district. As most of these application systems have insufficient capacity to meet crop demands opportunities to schedule irrigations were limited to start up after rain. Improvements in irrigation system performance were found to provide the greatest potential to increase sugarcane yield under conditions of limited water. Investigations identified that irrigation performance could be significantly improved through relatively minor adjustment. Field trials found that wind speed and direction significantly influenced the performance of travelling gun irrigators. Although growers were generally aware of the effects of wind, meteorological data suggested that the opportunity to operate water winches in low wind conditions is limited. Changing to a taper nozzle under moderate to high wind conditions will reduce the effect of wind on performance. This practice was found to improve the uniformity (measured by Christiansen’s Uniformity Coefficient, CU) by 16%. The grower survey indicated that there was no preference towards the use of taper nozzles in windy conditions. Additional trial work developed a relationship between the variation in water applied to the field through non uniformity and sugarcane yield. An 8% reduction in yield was determined for a 10% reduction in CU. This indicated that changing to a taper nozzle could potentially increase sugarcane yield by 15% in high wind conditions. Other settings, which also influenced uniformity, included lane spacing and gun arc angle Simple changes to the operation of furrow irrigation systems were also found to dramatically improve irrigation performance. Field measurements in combination with simulation modelling of irrigation events using SIRMOD II identified that current irrigation performance ranged in application efficiency from 45 to 99% (mean of 79%) and a distribution uniformity from 71 to 93% (mean of 82%). Both application efficiency and distribution uniformity were increased to greater than 90% and 84% respectively, except on a cracking clay soil. Improvements in application efficiency and distribution uniformity were achieved by adjusting furrow flow rate (cup size), turning the irrigation off at the right time (ie. just as it reached the end of the field) and banking the end of the field. Growers had a good understanding of the correct cut off time and were attentive to reducing run off through either banking ends or tail water return. However, growers had a poor understanding of the significance of furrow flow rate. Other opportunities to improve irrigation performance on high infiltration soils included alternate furrow irrigation and shallow cultivation practices which maintained compaction in the interspace and reduced infiltration. Soil moisture and crop growth measurements indicated that sugarcane yield could be maximised by starting the irrigation rotation earlier after rainfall (ie. at a deficit equal to the irrigation amount). These observations were modelled using the crop simulation model APSIM sugar to assess the strategy over a longer time interval and the influence of seasonal variation. Simulation modelling showed that final sugarcane yields were not sensitive to irrigation start-up strategies. Yields for the start-up strategies modelled varied by less than 5 tc/ha. This minor difference occurred as the crop yield was driven by the total amount of water available to the plant. The limited amount of irrigation water available to the plant (2 to 3 ML/ha) had only a minor effect on the water balance and no significant change to effective rainfall between strategies. The greatest difference in yield occurred between irrigation treatments when water was left over at the end of the season (9.2 tc/ha). Starting irrigation earlier after rainfall events (on a 14 day rotation) provided the greatest opportunity to use all of the available irrigation supply. By comparison, delaying the application of the first irrigation after rainfall resulted in some of the irrigation water not being applied in 30% of years.

Sailboat winches are used to help sailors manipulate the control lines that control the position and shape of the sails. Unlike most winches sailboat winches usually only have the ability to winch in the rope, but not to reverse. To reverse the line a sailor needs to manually manipulate it, this is both inconvenient and can also be a safety hazard. This master’s thesis will focus on the development of a self-locking braking system that will be used to allow a sailboat winch to reverse. The goal of the thesis is to design a braking system that works with a modified version of the E40i winch produced by Seldén. The braking system that was developed during this thesis is made up of two main parts, a one-way mechanism and a brake. The type of one-way mechanism that was chosen was an overrunning roller clutch. For the brake a wet disk brake was chosen with an outer diameter of 50mm and an inner diameter of 28.8mm. A 3D model of the braking system has been generated and materials have been selected so that the system is ready for prototyping and physical testing.

The project elaborated within engineering studies. The project is submitting design of technology production of precise holes for rolling bearings which are located in transmission case for the winch. Variants of production technologies were designed based on the construction drawings of transmission case. Chosen type of technology is boring. Boring was performed on the CNC machine DMF 180 produced by DMG MORI. DMF 180 allows precise production of bearings holes. Via selected criteria, it was selected the better variant of two. The criteria were: cylindricality, cohesiveness, position of elements and surface quality.

This report covers a bachelor thesis project to design a concept for a levelling system to a point absorbing wave energy converter that uses a winch with a chain, which has restricted capabilities to bending and thus requires a system which compensates for this. First of all, a literature study was made to see if there were any technologies that could be used, and also a wide search for information about the wave conditions in the Baltic sea were performed to find what requirements would be necessary for the concept to be able to withstand the conditions faced there. Following this, several brainstorming sessions were had to get ideas for different types of constructions that could solve the problem. After multiple ideas had been conceptualized, they were rated in a Pugh matrix with five different criteria which were: 1. mechanical complexity 2. complexity of required motion control 3. complexity of the structure 4. amount of potential critical weak points 5. mass of the system and lastly 6. how symmetrical it could be made. The concept that was deemed most viable out of all them is a cradle that holds the winch-drum and is controlled by a motor to compensate for one angular shift, and this is paired with a mooring system that limits the yawing motion of the entire buoy and thus removes the need for the compensation of that angle. This concept was then modelled in Solid Edge and following this; a stress analysis was made to determine the forces that would act upon the system. These were then used to determine whether the system would live up to the requirements or not with fatigue calculations. Lastly a list of recommended future work is presented. / Denna rapport täcker ett kandidatarbetsprojekt för att utforma ett koncept för ett nivelleringssystem till ett punktabsorberande vågkraftverk som använder en kedjevinsch med begränsad kapacitet till böjning och därmed kräver ett system som kompenserar för detta. Först gjordes en litteraturstudie för att se om det fanns teknik som kunde användas, och även en bred sökning efter information om vågförhållandena i Östersjön gjordes för att hitta vilka krav som skulle vara nödvändiga för att konceptet skulle kunna motstå dessa förhållanden. Efter detta hölls flera brainstormingssessioner för att få idéer för olika typer av konstruktioner som kunde lösa problemet. Efter att flera idéer hade konceptualiserats, bedömdes de i en Pugh-matris med fem olika kriterier som var: 1. mekanisk komplexitet 2. komplexitet för krävd rörelsekontroll 3. Strukturellkomplexitet 4. Antalet potentiella svaga punkter 5. Massan på systemet och slutligen 6. Hur symmetriskt systemet kunde göras. Det koncept som bedömdes vara mest genomförbart av dem alla var en vagga som håller vinschtrumman och styrs av en motor för att kompensera för en vinkelförskjutning, och detta är kombinerat med ett förtöjningssystem som begränsar girrörelsen för hela bojen och tar således bort behovet av kompensation av den vinkeln. Detta koncept modellerades sedan med Solid Edge och efter detta gjordes en kraftanalys för att bestämma krafterna som skulle agera på systemet. Dessa användes sedan för att bestämma om systemet skulle uppfylla kraven eller inte med utmattningsberäkningar. Till sist presenteras en lista med framtida arbete som rekommenderar.

This project has dealt with the developing a new technology for a renewable energy source, the wave energy, which is considered as one of the renewable resources with a potential to contribute to an energy production corresponding to about 10% of the world’s energy consumption nowadays. A point absorber concept that is using a Power Take-off (PTO) unit converts the sea surface wave motion into electricity thanks to a buoy at the sea surface which is moved by the waves. Due to harsh working conditions, the maintenance would cause too many issues, and a mooring system needs to be developed. The aim in this paper is to design a durable mooring system for at least 20 years of operation even working in a harsh sea environment. A geometry model of the mooring system has been built since the dimensioning of its components was performed. Several concepts were generated and evaluated with a Pugh matrix. An analysis of the different stresses affecting the performance of the system was made to validate the design. In addition, the detail design of the different parts of the system has made to allow their manufacture in future work. / Projektet har behandlat utvecklingen av en ny teknik för en förnybar energikälla, vågenergin, som anses vara en av de mest lovande förnybara resurserna med potential att bidra till en energiproduktion som motsvarar cirka 10 procent av världens energiförbrukning . Ett punktabsorberande koncept som använder en kraftuttagsenhet (PTO) omvandlar havsytans vågsrörelser till elektricitet. På grund av hårda arbetsförhållanden ger underhållsarbete stora problem och ett förtöjningssystem behöver utvecklas. Syftet med detta projekt är att utforma ett hållbart förtöjningssystem för minst 20 års drift, även i en hård havsmiljö. En geometrisk modell av förtöjningssystemet har skapats baserad på dimensionering av dess komponenter. Flera koncept genererades och utvärderades med en Pugh-matris. En simulering av de olika spänningar som påverkar systemets prestanda gjordes för att validera designen. Dessutom har detaljkonstruktion av de olika delarna av systemet gjorts, så att de kan tillverkas i ett framtida arbete.

Detta projekt undersöker konstruktionsmöjligheterna för ett nivellerande vinschsystem till ett vågkraftverk. Kedjekonstruktionen till detta vinschsystem består av länkar med låg tolerans för vrid- och skjuvspänningar och har begränsad böjlighet vilket innebär att vinschsystemet behöver kunna vinkelkompensera för att kedjan inte ska brista. Initialt togs flera koncept fram genom att utvärdera en kravspecifikation och se vilka problem som fanns. Dessa konceptförslag modellerades sedan i Solid Edge och en ny utvärdering gjordes där förslagen utvärderades med avseende på komplexitet, vinkelstyrning, servicebarhet och energiåtgång från styrsystemen. Det förslag som var mest lovande utifrån denna utvärdering består av en vagga i vilken vinschtrumman är upphängd. Lutningen av denna vagga kan styras av två motorer och rotationsrörelsen styrs av ett rälssystem med boggier. Detta förslag vidareutvecklades sedan med hjälp av ANSYS Workbench för att göra konstruktionen lättare, undersöka utmattningsproblem samt se var spänningskoncentrationer uppstår. Från denna analys togs kravprofiler fram för ett antal komponenter som konstruktionen kräver för att kunna drivas. Vidare analys av växel, motor, lager samt energiåtgång kommer krävas för att utvärdera om hurvida konstruktionen är lönsam att bygga. / This project examines the design possiblilites for a self-leveling winch system for a wave power converter. The chain design for this winch consists of links with limited resistance to torsional shear and bending shear stress and with limited bending capabilities, which requires the winch construction to be able to compensate for angular changes to prevent the chain from breaking. Initially several designs were made by evaluating a specification of requirements and by examining the problems facing a winch based wave power converter. These designs were modelled in Solid Edge and evaluated based on complexity, angular steering, servicability and energy requirements for the control systems. The most promising of these designs is composed of a cradle in which the winch drum is mounted. The inclination of the cradle is controlled by electric motors and the rotation is controlled by a rail system with boggies. The design was then further improved upon by utilising ANSYS Workbench to decrease the mass of the design, examining problems related to fatigue failure, and studying stress concentrations. Based on this analysis a set of requirements were specified for a number of key components required for controlling the winch system. Further analysis of the transmission, motor, bearings and energy requirements for the control systems will be needed to evaluate wether the design is profitable to build.

The aim of this thesis is to design a conceptual self-propelled forestry winch for removing and skidding in thinning steep terrain. The thesis contains patent search of design solutions the machines using in the field, conceptual design of structural layout, assembly drawing overall concept of the equipment and drawing concept chassis design.

When working under water at great depths, or in tough environments, remotely controlled underwater vehicles, so called ROV:s, are a good tool too use. With the help of these robots it is possible to work for longer periods of time and at larger depths then with ordinary divers. Ocean Robotics is a company from Linköping, Sweden, that has over 40 years of experience with ROV:s. They produce several different models for different kind of jobs. The purpose of this project was to develop a concept of a device that keeps the tension constant on the tether that connects the ROV with the operator. The tension needs to be constant when the tether is being rolled in on and out from the winch. The work was executed on behalf of Ocean Robotics and a prerequisite was that it should be possible to integrate the device with the winch system they have today. The work have followed Ulrich and Eppingers method for product development and together with requirements from the contractor several concepts was generated. The concepts were validated in a decision matrix and the concepts with the highest score was modeled in the CAD-program CREO Parametrics. The concepts got further developed and was compared against each other once again. Which generated the final concept. Furthermore a couple of friction tests were executed to find appropriate materials for the construction. The final concept will be mounted on the winch and connected to Ocean Robotics self reversing screw. To measure the tension on the tether a load cell is used and the tether is fed by a rubberized wheel that is driven by an electric motor. To adjust the force around the tether a trapezoidal thread is driven by another electric motor, which adjust the pinch wheels height. The tether goes as a tangent between the two wheels that has a profile that insures that the force goes around the tether.