Truck Model for Yaw Dynamics Control

This report describes the derivation of a nonlinear model of a tractor-semitrailer combination vehicle. The purpose of the model is validation of yaw-control algorithms. The model include 4 DOF in lateral, longitudinal, and yaw motion. It is formulated as a state-spece model with 5 state variables. Additional states are added with the rotational dynamics of the wheels. The model includes a static description of load-transfer, and a fairly detailed tyre model. A linearized version of the model is also presented. The nonlinear model is implemented in Simulink (TM). Validation is performed by comparison with a multibody model. Examples of simulation outputs are given

Kväveomsättning i gräsmark med olika artantal och artsammansättningar

This study was carried out at the Swedish University of Agricultural Sciences, Dept. of Agricultural Research for Northern Sweden. The aim of the study was to determine how plant species richness and diversity influence the nitrogen pools and nitrogen fluxes in the soil. Plant and soil samples from a biodiversity experiment in grasslands were used. Thirty plots with 12 grassland plant species (legumes, grasses, and non-legume herbs), combined from 1-12 species were investigated. The aboveground biomass was harvested in mid-August 2002. In late October the soil was sampled and collected for analyses in the laboratory. Plant diversity and composition play an important role for nitrogen cycling in soil and sustainability of plant production. The total plant biomass increased with increased number of species and when legumes were included in the plant communities. Nitrogen concentration and nitrogen content in plant biomass increased with an increasing fraction of legumes. Anaerobic nitrogen mineralization rate was slower in soil from plots with monocultures than from more species-rich plant communities, especially 12-species mixtures. Potential nitrification was positively correlated to legume biomass as a percentage of total plant biomass. Communities with a mix of legumes, grasses and herbs had the highest concentrations of ammonium (extracted from soil by KCl). This could be explained by high nitrogen mineralization. Concentrations of nitrate were much higher in plots with only legume species. The results from this study support the view that high plant diversity can reduce the risk for nitrate leaching and also allow a more efficient exploitation of available resources.Detta projekt utfördes vid Sveriges lantbruksuniversitet, Institutionen för norrländsk jordbruksvetenskap, Umeå. Syftet med studien var att undersöka hur antalet växtarter och artsammansättningen påverkar kväveomsättningen i marken. Studien omfattar 30 försöksytor med 12 olika arter av gräsmarksväxter (gräs, baljväxter och örter) i kombinationer från 1-12 arter. Växtprovtagningen gjordes i mitten av augusti 2002 och jordprovtagningen gjordes i oktober 2002. Artantalet och artsammansättningen visade sig vara av stor betydelse för kvävets kretslopp. Växtbiomassan ökade med ökat antal arter och då baljväxter fanns med i artblandningen. Kvävekoncentrationen och den totala kvävemängden i växtbiomassan ökade med en ökande andel baljväxter i växtbiomassan. Anaerob kvävemineralisering var långsammare i jord från försöksytor med en art än i jord från flerartsytor, speciellt 12-artsytor. Nitrifikations-potentialen var positivt korrelerad till den procentuella andelen baljväxter i växtbiomassan. Extrahering av ammonium visade att ytor med en blandning av baljväxter, gräs och örter hade högst ammoniumkoncentration. Detta kan förklaras av den höga kvävemineraliseringen i dessa ytor. Försöksytor med enbart baljväxter hade kraftigt förhöjda nitratkoncentrationer. Denna studie stöder uppfattningen att resursutnyttjandet hos växtsamhällen med många arter kan bli mera effektivt och därmed även minska risken för förlust av nitrat

Measurements of knee rotation-reliability of an external device in vivo

<p>Abstract</p> <p>Background</p> <p>Knee rotation plays an important part in knee kinematics during weight-bearing activities. An external device for measuring knee rotation (the Rottometer) has previously been evaluated for validity by simultaneous measurements of skeletal movements with Roentgen Stereometric Analysis (RSA). The aim of this study was to investigate the reliability of the device.</p> <p>Method</p> <p>The within-day and test-retest reliability as well as intertester reliability of the device in vivo was calculated. Torques of 3, 6 and 9 Nm and the examiner's apprehension of end-feel were used at 90°, 60° and 30° of knee flexion. Intraclass Correlation Coefficient _2,1(ICC _2,1), 95% confidence interval (CI) of ICC and 95% CI between test trials and examiners were used as statistical tests.</p> <p>Result</p> <p>ICC_2,1ranged from 0.50 to 0.94 at all three flexion angles at 6 and 9 Nm as well as end-feel, and from 0.22 to 0.75 at 3 Nm applied torque.</p> <p>Conclusion</p> <p>The Rottometer was a reliable measurement instrument concerning knee rotation at the three different flexion angles (90°, 60° and 30°) with 6 and 9 Nm applied torques as well as the examiner's apprehension of end-feel. Three Nm was not a reliable torque. The most reliable measurements were made at 9 Nm applied torque.</p

Orthopaedic measurements with computed radiography. Methodological development, accuracy, and radiation dose with special reference to the weight-bearing lower extremity and the dislocating patella

The overall aim of this study was to develop and evaluate a measurement system for computed radiography (CR) and Picture Archiving and Communication Systems (PACS), permitting measurements of long distances and angles in and between related images. The developed measurement system, which was based on the QUESTOR Precision Radiography (QPR) system, was applied to the weight-bearing knee with special reference to the dislocating patella. The QPR system modified for CR fulfilled the criteria for measuring the weight-bearing knee. The special measuring assistance tools that were developed were important for the implementation of CR and PACS, particularly in workstations programmed for musculoskeletal radiology. The energy imparted to the patient was reduced by 98% at the lowest exposure of the CR –system, compared with our conventional analogue method, without loss of diagnostic accuracy. The CR technique creates a possibility, to an extent not previously feasible, to differentiate the exposure parameters (and thus minimise the radiation dose to the patient) by carefully considering the purpose of the examination. A radiographic method for measuring the rotation of the femur and the tibia, the Q-angle, and the patellar translation was developed and applied to healthy volunteers. The introduced patellar variables have yielded new insights into the complex sequence of motions between the femur, tibia, and patella. The patients with a dislocating patella were subdivided into one “clean” group of spontaneous dislocations and one group with various traumas in the history, which thus resulted in two groups with distinct radiographic differences. The Q-angle was decreased in knees that had suffered dislocations, and the traditional surgical treatment with a further reduction of the Q-angle must be challenged. The use of clinical measurements of the Q-angle was not an optimal way to evaluate the mechanical alignment in the patellofemoral joint under physiological conditions. In this study, we have proved that the developed method for CR and PACS is a useful technique for measurements in and between related images, and is superior to the conventional analogue technique

Utstationering av utländska arbetstagare i Sverige : Är Lex Britannia och Sveriges sätt att implementera utstationeringsdirektivet (96/71/EG) förenliga med EG-rätten?

The Latvian building company Laval un Partneri Ltd (Laval) posted Latvian construction workers at the rebuilding of a school in Vaxholm in autumn 2004. Because the company refused to sign a collective agreement with Svenska Byggnadsarbetareförbundet (Byggnads), which is the Swedish trade union for constructions workers, Byggnads put the construction site under a boycott. Next Laval sued Byggnads for damages in the Swedish Labour Court (AD) because Laval considers the boycott as well as Byggnad´s demand that Laval signs a collective agreement incompatible with EC Law. AD has now demanded a preliminary ruling from the European Court of Justice (ECJ). While waiting for the preliminary ruling from the ECJ, several important questions of principle stand unanswered. Two such questions are whether Lex Britannia and the way in which Sweden har implemented the directive for posted workers (96/71/EC) are compatible with EC Law. In this thesis the author seeks to answer these two questions.Det lettiska byggbolaget Laval un Partneri Ltd (Laval) utstationerade under hösten 2004 lettiska byggarbetare på ett skolbygge i Vaxholm. Eftersom bolaget vägrade teckna kollektivavtal med Svenska Byggnadsarbetareförbundet (Byggnads) satte Byggnads bygget i blockad. Laval stämde därefter Byggnads i Arbetsdomstolen (AD) och krävde skadestånd eftersom Laval anser att blockaden, liksom Byggnads krav på att Laval skulle teckna kollektivavtal, strider mot EG-rätten. AD har nu begärt ett förhandsavgörande i målet från EG-domstolen. I avvaktan på EG-domstolens avgörande står flera principiellt viktiga frågor i målet obesvarade. Dessa är bl a huruvida Lex Britannia och Sveriges sätt att implementera utstationeringsdirektivet (96/71/EG) är förenliga med EG-rätten. Det är dessa frågor som författaren ämnar besvara i uppsatsen

Duty of Disclosure when Seeking Employment : A general contract law principle affected by employment law principles of protection of employees

The general contract law principle of loyalty between negotiators, in deliberation, leads to a duty of disclosure for negotiators. The extent of this duty of disclosure is influenced by many different factors; amongst others the type of agreement, the negotiators knowledge and opportunity of procuring knowledge. The general duty of disclosure is both a part of the contract law principle of loyalty between negotiators in negotiating a contract, and an indirectly statutory obligation, that, if neglected will lead to nullification of the agreement. The legislator has stated that the general contract law, Lag (1915:218) om avtal och andra rättshandlingar på förmögenhetsrättens område (avtalslagen), should be used to regulate negotiating of contracts, including the negotiation of contracts of employment. In arbetsdomstolens judging, additional factors have been weighed in, and the judgement is done also through the use of a concept taken from employment law, the concept of ”saklig grund för uppsägning”. Arbetsdomstolen appear to prefer using employment law and principles of protection for the employee, even though the legislators opinion was that general contract law should regulate negotiations of contracts of employment. This way, other factors are included in the judging of the duty of disclosure when seeking employment than in the general judging of duty of disclosure. Amongst other the interests of society and the will of protecting the person seeking employment, affects arbetsdomstolens judging of the duty of disclosure in negotiating contracts of employment. The thesis arguments that this interpretation, of the confines between contract law and employment law, is contrary to the statements of the legislator, and also an unfit interpretation of the principle of duty of disclosure, in terms of reaching partition of risks between negotiators of contracts of employment