<p>När paket transporteras vintertid kommer dessa att kylas ned av den låga utomhustemperaturen. Vid ankomst till sorteringsterminalen kommer paketen ha antagit en lägre temperatur än den i terminalen. Under tiden som paketen hanteras i terminalen kommer deras temperatur att stiga på grund av den högre inomhustemperaturen. Detta medför ett ökat uppvärmningsbehov i terminalen vilket således bidrar till en ökad uppvärmningskostnad och miljöpåverkan.</p><p> </p><p>Syftet med detta examensarbete är att ta fram en modell som beskriver energiflödet under transport och sortering för att kunna beräkna storleken på det ökade energibehovet som uppstår i paketterminalerna vintertid då nedkylda paket hanteras. Energibehovet skall sedan sättas i samband med den extra uppvärmningskostnad och miljöpåverkan som paketen ger upphov till. Syftet har sammanställts i fyra frågor.</p><p> </p><ul><li>Hur kan paketens temperatur i paketnätverket beskrivas matematiskt?</li><li>Hur stort är det extra energibehovet som uppstår då nedkylda paket värms upp i Posten Logistiks paketterminaler?</li><li>Vilken är merkostnaden för terminalernas extra energibehov?</li><li>Vilken miljöpåverkan medför det extra energibehovet?</li></ul><p> </p><p>För att nå fram till ett resultat har teorier och samband inom värmeöverföring använts. För att skaffa kunskap inom området har därför en del kurslitteratur studerats. Viktig kunskap har även inhämtats mer praktiskt genom studiebesök, intervjuer och informationsmöten med sakkunniga personer. Telefonkonversationer och E-postkorrespondenser har även varit viktiga för informationsinhämtningen. En serie temperaturmätningar utfördes för att visualisera problemet och få en bild av ett pakets temperaturförändring i distributionsnätverket. Testmätningar utfördes för att verifiera att de vetenskapliga modellerna var applicerbara på det aktuella problemet. Därefter utfördes mätningar i verklig miljö, dels i terminalerna, men även under transport.</p><p> </p><p>Efter de första mätningarna ansågs ”Lumped Capacitance Method” vara tillräcklig för att beräkna paketens temperaturförändring. Detta konstaterande ändrades dock när paket av olika material användes till temperaturmätningarna. Slutsatsen blev att en mer avancerad modell, som tar hänsyn till paketens värmekonduktivitet, bör användas för att beräkna paketens temperaturförändring. Då en sådan formel används kan en temperatur som ligger nära verkligheten beräknas för paketen. Tyvärr har materialparametrarna varit svåra att beräkna då någon tydlig statistik över paketens innehåll inte finns att tillgå.  Det extra energibehov som uppstår då nedkylda paket värms upp i Posten Logistiks paketterminaler kommer att skilja sig åt avsevärt beroende på materialsammansättningen. Samma sak gäller för merkostnaden och miljöpåverkan för det extra energibehovet. Därför är rekommendationen att utföra en mer omfattande studie av paketens innehåll. De största kunderna kan exempelvis uppmanas att presentera statistik över sina försändelser och hur de är paketerade.</p> / <p>Packages that are transported during winter will be cooled by the low temperature outside the transport carriage. When arriving to the sorting terminal the packages will have a lower temperature compared to the air inside the terminal. During the time the packages reside in the terminal, the packages will increase in temperature. This will cause an increased need for heating which in turn leads to a higher cost and environmental effects.</p><p> </p><p>The aim of my degree project is to present a model that describes the packages’ energy flow during transportation and time in the terminal. I will then calculate the need for increased heating during winter because of the packages. The result will be described in increased heating, cost and environmental effects. The aim can be summarized in four questions.</p><p> </p><ul><li>How can the packages’ temperature within the package network be described mathematically? </li><li>How does the need for heating increase due to the cold packages in Posten Logistik’s terminals?</li><li>How does the cost increase due to the packages?</li><li>What are the environmental effects?</li></ul><p> </p><p>I have studied course literature to achieve sufficient knowledge in the area and I have used theories and correlations in heat transfer to reach the aim. Information in the more practical area has been collected during visits, interviews and meetings with experts. Telephone interviews and E-mail conversations were also important. A series of temperature measurements were made to visualize the problem and to get a picture of the temperature changes of the packages within the distribution network. Some test measurements were made to verify that the scientific theories were applicable on the problem. Later, measurements were made in the real setting, i.e. in the terminals and during transportation.</p><p> </p><p>After the first measurements it seemed like Lumped Capacitance Method was sufficient to calculate the temperature variation of the packages. That statement was changed when packages with different materials were used in the temperature measurements. The conclusion was made that a more advanced formula, one that takes the packages’ thermal conductivity into consideration, was needed to calculate the result. With the advanced formula a temperature of the packages can be calculated that is close to reality. Unfortunately, the material parameters of the packages were difficult to calculate when no obvious statistics of the contents of packages is available. The level of increased heating due to the cold packages in Posten Logistik’s terminals will differ if the materials in the packages changes. The same thing happens to the cost and environmental effects. Therefore the recommendation is to perform a study of the content of packages. The largest customers could be asked to present statistics over their postal items and used wrapping.</p>

No description available.

Nitrogen fertilization is important in attaining high yielding, quality tobacco. However, practices that use excessive N can be uneconomical, threaten the environment and produce leaves that are high in nitrates. Leaves high in nitrates have been positively correlated with leaves that are high in tobacco specific nitrosamines (TSNA), which are considered potent carcinogens. Competition from cheaper, foreign leaf, increasing costs of fertilizers and new market structures which show purchasers seeking low TSNA leaf demand that producers become more efficient in their N use. The objective of this study is an examination of burley (TN 90) and dark (KY 171) tobacco cultural practices with the hypothesis that optimizing growing conditions will enhance N efficiency. This experiment took place during 2005 and 2006 in the traditional tobacco growing regions of Springfield (Dickson silt loam) and Greeneville, TN (Lindside silt loam). Experimental isolated growing condition variables. Irrigation treatments isolate the importance of soil moisture. Fertigation, while using irrigation practices, isolates the effects of synchronizing crop N demand with N supply. Plasticulture, using fertigation protocol, isolates the importance of soil temperature. Season long measurements of soilwater tension, soil temperature and leaf nitrates were used to evaluate the ability of each practice to keep plants in optimal N uptake and utilization growing conditions. Results showed that the most dramatic and consistent treatment effects were found in the TSNA analysis. Even during a season characterized by precipitation being sufficient in volume and timing to meet plant water demands, irrigation was successfully able to decrease TSNA concentration by about 30%. During drier growing seasons, TSNA was reduced by 50% or more. Measurements of leaf nitrates taken with a Horiba monitor were able to consistently detect treatment and N rate differences. The last sample taken around eight weeks after transplanting correlated strongly with TSNA content (0.81). This tool could prove effective in characterizing optimal N management. Cultural practices that offer control over soil water tension, nitrate content in leaves and soil temperatures can be effective in increasing the ability of the plant to uptake and utilize N towards achieving high yielding, high GRI quality and low TSNA leaf.

The subject of this thesis is modeling of the manufacturing process of high voltage power cables with the aim of predicting residual stresses and strains in the cable insulation. The studied material is cross-linked polyethylene (XLPE), which at room temperature is a semi-crystalline viscoelastic solid. Above the crystallization temperature the material exhibits a rubber type behavior due to the crosslinks. An extensive set of uniaxial tensile relaxation tests were used for the mechanical characterization of XLPE. These experiments were complemented by pressure volume temperature experiments as well as density and crystallinity measurements. Based on the experiments, initially a linear and later a non-linear viscoelastic power law model was formulated, incorporating temperature and crystallinity dependence. The non-linear model is based on the Schapery formulation. Evaluations of the model were performed with additional uniaxial experiments. These included comparisons between predicted stress responses and measured values during relaxation tests with transient temperature histories, during two step relaxation experiments and during uniaxial tests with constant strain rate loading. The initial modeling work focused on the prediction of residual stresses which develop during the cooling stage of the manufacturing process. As the constitutive model incorporates temperature and crystallinity dependence, the mechanical problem is coupled to the heat transfer and crystallization problems. Calculations were performed for a vertical manufacturing line. The effects of a viscoelastic material model are illustrated by a comparison to a stress state predicted by a thermo-elastic material model. A final study concerns the modeling of the residual strains in the insulation. It was found that strains originating at cross-linking of the molecules play a signifi- cant role for buildup of residual strains. Calculations are performed for the same vertical process line as before. Good agreement was found between predicted and experimentally obtained residual strains. Based on the residual strain state an estimate is made for the upper limit of shrink-back of the cable insulation. / QC 20100915

När paket transporteras vintertid kommer dessa att kylas ned av den låga utomhustemperaturen. Vid ankomst till sorteringsterminalen kommer paketen ha antagit en lägre temperatur än den i terminalen. Under tiden som paketen hanteras i terminalen kommer deras temperatur att stiga på grund av den högre inomhustemperaturen. Detta medför ett ökat uppvärmningsbehov i terminalen vilket således bidrar till en ökad uppvärmningskostnad och miljöpåverkan.   Syftet med detta examensarbete är att ta fram en modell som beskriver energiflödet under transport och sortering för att kunna beräkna storleken på det ökade energibehovet som uppstår i paketterminalerna vintertid då nedkylda paket hanteras. Energibehovet skall sedan sättas i samband med den extra uppvärmningskostnad och miljöpåverkan som paketen ger upphov till. Syftet har sammanställts i fyra frågor.   Hur kan paketens temperatur i paketnätverket beskrivas matematiskt? Hur stort är det extra energibehovet som uppstår då nedkylda paket värms upp i Posten Logistiks paketterminaler? Vilken är merkostnaden för terminalernas extra energibehov? Vilken miljöpåverkan medför det extra energibehovet?   För att nå fram till ett resultat har teorier och samband inom värmeöverföring använts. För att skaffa kunskap inom området har därför en del kurslitteratur studerats. Viktig kunskap har även inhämtats mer praktiskt genom studiebesök, intervjuer och informationsmöten med sakkunniga personer. Telefonkonversationer och E-postkorrespondenser har även varit viktiga för informationsinhämtningen. En serie temperaturmätningar utfördes för att visualisera problemet och få en bild av ett pakets temperaturförändring i distributionsnätverket. Testmätningar utfördes för att verifiera att de vetenskapliga modellerna var applicerbara på det aktuella problemet. Därefter utfördes mätningar i verklig miljö, dels i terminalerna, men även under transport.   Efter de första mätningarna ansågs ”Lumped Capacitance Method” vara tillräcklig för att beräkna paketens temperaturförändring. Detta konstaterande ändrades dock när paket av olika material användes till temperaturmätningarna. Slutsatsen blev att en mer avancerad modell, som tar hänsyn till paketens värmekonduktivitet, bör användas för att beräkna paketens temperaturförändring. Då en sådan formel används kan en temperatur som ligger nära verkligheten beräknas för paketen. Tyvärr har materialparametrarna varit svåra att beräkna då någon tydlig statistik över paketens innehåll inte finns att tillgå.  Det extra energibehov som uppstår då nedkylda paket värms upp i Posten Logistiks paketterminaler kommer att skilja sig åt avsevärt beroende på materialsammansättningen. Samma sak gäller för merkostnaden och miljöpåverkan för det extra energibehovet. Därför är rekommendationen att utföra en mer omfattande studie av paketens innehåll. De största kunderna kan exempelvis uppmanas att presentera statistik över sina försändelser och hur de är paketerade. / Packages that are transported during winter will be cooled by the low temperature outside the transport carriage. When arriving to the sorting terminal the packages will have a lower temperature compared to the air inside the terminal. During the time the packages reside in the terminal, the packages will increase in temperature. This will cause an increased need for heating which in turn leads to a higher cost and environmental effects.   The aim of my degree project is to present a model that describes the packages’ energy flow during transportation and time in the terminal. I will then calculate the need for increased heating during winter because of the packages. The result will be described in increased heating, cost and environmental effects. The aim can be summarized in four questions.   How can the packages’ temperature within the package network be described mathematically? How does the need for heating increase due to the cold packages in Posten Logistik’s terminals? How does the cost increase due to the packages? What are the environmental effects?   I have studied course literature to achieve sufficient knowledge in the area and I have used theories and correlations in heat transfer to reach the aim. Information in the more practical area has been collected during visits, interviews and meetings with experts. Telephone interviews and E-mail conversations were also important. A series of temperature measurements were made to visualize the problem and to get a picture of the temperature changes of the packages within the distribution network. Some test measurements were made to verify that the scientific theories were applicable on the problem. Later, measurements were made in the real setting, i.e. in the terminals and during transportation.   After the first measurements it seemed like Lumped Capacitance Method was sufficient to calculate the temperature variation of the packages. That statement was changed when packages with different materials were used in the temperature measurements. The conclusion was made that a more advanced formula, one that takes the packages’ thermal conductivity into consideration, was needed to calculate the result. With the advanced formula a temperature of the packages can be calculated that is close to reality. Unfortunately, the material parameters of the packages were difficult to calculate when no obvious statistics of the contents of packages is available. The level of increased heating due to the cold packages in Posten Logistik’s terminals will differ if the materials in the packages changes. The same thing happens to the cost and environmental effects. Therefore the recommendation is to perform a study of the content of packages. The largest customers could be asked to present statistics over their postal items and used wrapping.

Arbetet utfördes på Sura Magnets, ett företag i Söderköping som bl.a. tillverkar formsprutade plastbaserade magneter. En av deras produkter kallad ”10 mm:aren” tillverkas genom formsprutning. Varje skott ger 6 detaljer. Problemet de har är, att ofyllda skott kan tillverkas. För att undvika att dessa ofyllda detaljer når kunderna, gör man en manuell avsyning, vilket är ett väldigt tidskrävande arbete. Syftet med arbetet var att tillverka en automatiserad utrustning som via vikt kontroll ska avskilja de kasserade skotten. Efter att ha införskaffat information om problemen, genererades ett antal koncept för att lösa dessa. Efter att ett koncept blivit valt, konstruerades en automatiskviktkontroll mekaniskt och elektriskt. Därefter tillverkades ett PLC program för att styra utrustningen. Dessvärre hann inte alla detaljer till utrustningen tillverkas, så den har inte kunnat testas i praktiken. Detta överlåtes till Sura Magnets att utföra. Hoppas att konstruktionen kommer att utföra det avsedda arbetet på ett tillfredställande sätt. / The assignment was executed at Sura Magnets, a company located in Söderköping, which among other things manufactures injection moulded plastic based magnets. One of their products, called “10 mm:aren", are produced through injection moulding. Each cycle produces 6 details. Their problem is that during the injection moulding process some incomplete details can be manufactured. To prevent these incomplete details from reaching their customers, they have to manually check all produced details, which is a wary time consuming task. The purpose of my assignment was to manufacture an automated device that, through weight control, separated the cycles that contained incomplete details from the ones that didn’t. After gaining some knowledge about the problems, a number of concepts were generated to solve these problems. when one of the concepts was chosen, an automated weight control was constructed both mechanically and electrically. Then a PLC Program was constructed to run the device. Unfortunately all the details to complete the device weren’t manufactured because of time shortage, so the device hasn’t been tested in the field. The assembling and testing of the device are left for Sura Magnets to complete. I hope that the device will perform the task it was designed for with satisfying results.

No description available.

<p>A project to construct a high-speed road deflection tester was initiated in the 1991. A mid-sized truck was used as a carrier for the first prototype. The results were promising and it was decided to build a full-size truck system. The new vehicle, based on a Scania R143 ML, was completed in 1997.</p><p>The Road Deflection Tester (RDT) is equipped with two arrays of twenty noncontact laser sensors that collects transversal surface profiles at normal traffic speeds. One profile, placed between the wheel axles, constitutes an unloaded case. The other profile, just behind the rear axle of the vehicle, constitutes the loaded case. By subtracting the front cross profile from the corresponding rear one, the "deflection profile" is assessed. The deflection is assumed to vary with the stiffness of the road.</p><p>In order to produce a large load on the rear wheels the engine was mounted in the back of the vehicle, slightly behind the rear axle. In testing mode the rear axle force is approximately 112 kN, and the front axle force is about 30 kN. An incremental wheel pulse transducer, two force transducers and two accelerometers, an optical speedometer and a gyroscope are also mounted on the RDT.</p><p>The first test programme was carried out in 1998. Due to the careful choice of test sections, data from these sections still produce the best results. A smaller test programme was carried out in 2001, and a larger one in 2002 when the RDT was taken to England and France for demonstration. Promising results, both on an aggregated scale and for individual test sections, have been obtained. The RDT compares favourably with the Falling Weight Deflectometer.</p><p>Short histories of road construction and road research give some historical and cultural background to the more recent developments. A more comprehensive history of rolling deflectographs presents all devices found in the literature from the start in the mid-fifties when the California Traveling Deflectograph and Lacroix Deflectograph were constructed, to the latest laser based High-Speed Deflectograph. Many references are given for further reading.</p><p>The data acquisition hardware on the RDT system consist of sensors, signal converters, signal processing cards, an industrial computer for data communication, and an ordinary PC for operating the equipment and data storage. The software used to evaluate the data is written entirely in Matlab. Many levels of pre-processing make evaluation relatively fast, and the modularised design makes it easy to implement new evaluation algorithms in a clean and efficient way.</p><p>A literature survey on the deformations of solids under static and moving load is presented in Appendix A. The static case started with Boussinesq in 1885, was much developed in the sixties, but since the eighties only a very limited amount of new results have been published. The moving load case, on the other hand, is still an field of active research and development.</p>

<p>Several fatigue criteria were evaluated with experimental fatigue test data. The fatigue tests contained many different geometries with different degrees of stress concentration. It was concluded that the differences between the criteria were neglectable when compared to the differences between the specimens. The stress concentrations with the stress gradients and sizes of the highly stresses volumes that resulted were very important. In order to understand this, gradient and volume methods were investigated. The gradient methods showed some improvement over the strictly local evaluation first attempted. The volume method, a weakest link application with a Weibull distribution of the fatigue strength, yielded results useable for actual design situations. The volume method is strongly recommended and the choice of criterion does not seem to be very important.</p>

<p>This licentiate thesis is generally concerned with the ductile failure and rupture mechanisms encountered under combined tension and torsion loading. In the first part entitled Paper A, an experimental investigation of the rupture mechanisms in a mid-strength and a high strength steel was conducted employing a novel test configuration. The specimen used was a double notched tube specimen loaded in combined tension and torsion at a fixed ratio. The effective plastic strain, the stress triaxiality and the Lode parameter was determined in the centre of the notch at failure. Scanning electron microscopy of the fractured surfaces revealed two distinctively different ductile rupture mechanisms depending on the stress state. At high stress triaxiality the fractured surfaces were covered with large and deep dimples, suggesting that growth and internal necking of voids being the governing rupture mechanism. At low triaxiality it was found that the fractured surfaces were covered with elongated small shear dimples, suggesting internal void shearing being the governing rupture mechanism. In the fractured surfaces of the high-strength steel, regions with quasi-cleavage were also observed. The transition from the internal necking mechanism to the internal shearing mechanism was accompanied by a significant drop in ductility.</p><p>In the second part entitled Paper B, a micromechanics model based on the theoretical framework of plastic localization into a band introduced by Rice is developed. The model employed consists of a planar band with a square array of equally sized cells, with a spherical void located in the centre of each cell. The periodic arrangement of the cells allows the study of a single unit cell for which fully periodic boundary conditions are applied. The micromechanics model is applied to analyze failure by ductile rupture in experiments on double notched tube specimens subjected to combined tension and torsion carried out by the present authors. The stress state is characterized in terms of the stress triaxiality and the Lode parameter. Two rupture mechanisms can be identified, void coalescence by internal necking at high triaxiality and void coalescence by internal shearing at low triaxiality. For the internal necking mechanism, failure is assumed to occur when the deformation localizes into a planar band and is closely associated with extensive void growth. For the internal shearing mechanism, a simple criterion based on the attainment of a critical value of shear deformation is utilized. The two failure criteria capture the transition between the two rupture mechanisms successfully and are in good agreement with the experimental result.</p>