Effect of Central tire inflation on weak forest roads

Nybyggnation och underhåll av skogsbilvägar medför stora kostnader för skogsbruket i Sverige. Därför är det av intresse att finna metoder för att minska dessa kostnader. Ett tillvägagångssätt kan vara att utrusta virkesfordon med Central Tire Inflation (CTI). CTI är ett system som kan sänka och höja ett fordons däckstryck under färd. Tidigare studier har konstaterat att när virkesfordon sänker däckstryck blir spårbildning mindre. Därför kan det vara möjligt att dimensionera vägar som enbart trafikeras av CTI-utrustade virkesfordon med tunnare överbyggnad. Studier som bekräftat detta har genomförts, dock inte i Sverige. Syftet var att jämföra spårbildningen av ett fullastat virkesfordon med släp som har lågt eller högt däckstryck. Jämförelsen utfördes på skogsbilvägar med en underbyggnad av normalmorän och både vid trafikering direkt på underbyggnaden eller på ett 5 cm tjock bärlager. En spårdjupsstudie genomfördes i oktober 2013. Ett CTI-utrustat virkesfordon trafikerade olika vägavsnitt med lågt eller högt däckstryck. Virkesfordonet var fullastat med bruttovikten 61 500 kg. Spårbildningen mättes efter var sjätte överfart tills 30 överfarter genomförts. På ingen av försökssträckorna uppstod svår spårbildning, utan maximalt uppmätt spårdjup var 27 mm. Lågt däckstryck gav mindre spårbildning men differensen mot högt däckstryck var liten (3,4-10,5 mm). Dock var skillnaden statistiskt signifikant på två av försökssträckorna. Det innebär att på skogsbilvägar med en underbyggnad av normalmorän kan tillgänglighetsklass C uppnås utan bärlager och oavsett däckstryck. Det innebär en besparingspotential för Holmen Skog då de normalt lägger 810 ton bärlager per km på dessa vägar för att uppnå tillgänglighetsklass C.Construction and maintenance of forest roads is costly for the forest industry in Sweden. It is therefore of interest to investigate methods to reduce these costs. One possible method is to equip timber vehicles with Central Tire Inflation (CTI). CTI is a system that can change the tire pressure while the vehicle is driving. Previous studies have found that timber vehicles equipped with CTI and thereby operating with reduced tire pressure create less rutting than conventional vehicles. It suggests that forestry roads travelled exclusively by timber vehicles equipped with CTI can be constructed with a thinner base course without reduced accessibility. Studies have confirmed this but none of them has been conducted in Sweden. The aim was to compare the rutting on a forest road when travelled by a fully loaded timber vehicle with trailer at high and low tire pressure. The trial was conducted on a forest road with a subgrade of normal till and sections with 5 cm thick base course. The comparison was carried out on both the subgrade and the sections with a base course. A field study was conducted in October 2013. A timber vehicle equipped with CTI travelled different road sections with low and high tire pressure. The timber vehicle was loaded with a gross weight of 61 500 kg. Rutting was measured after every six overpasses until 30 overpasses were completed. On none of the test sections were severe rutting created and maximum measured rut depth was 27 mm. Low tire pressure yielded less rutting but the difference to high tire pressure was small (3.4 to 10.5 mm), although significantly different on two test sections. This means that forest roads with a subgrade of normal till can achieve access class C without a base course and regardless of tire pressure. This means a great savings potential for Holmen Skog as they normally put 810 ton of base course per km to achieve access class C

Identification of conflict stands by means of laser scanning

The interest in harvesting wood fuel in conflict stands has grown in recent years as a consequence of the increased demand for biofuel. Conflict stands are young forests that have not been cleaned and have a large number of stems ha-1with a great height and diameter distribution. This means that traditional field measurements in conflict stands are difficult and very time consuming. Therefore, the forestry sector is in need of new, more efficient inventory methods. In this study, the Lidar data from Lantmäteriet’s (the Swedish mapping, cadastral and land registration authorities) new national height model was used in combination with plots from the Swedish national forest inventory from 2009 to create functions for; height, volume, diameter and number of stems. The functions were used to create rasters corresponding to the estimated variables. The basis for the identification of the conflict stands in the rasters was the criteria for: height, volume and diameter. In the study 112 plots was used to estimate the basal area weighted mean height. In the estimation of diameter in breast height, volume and stem numbers 33 sample plots were used after the stratification based on the average height (<12 m). The results show that the function for basal area weighted mean height had an adjusted determination degree (R2-adj) of 92,0 % and a standard deviation (SD) of 1.4 m. Volume and diameter had anR2-adj of 88.2 % and 75,6 %, SD of 11.5 m3sk ha-1 and 15,3 mm. The high accuracy of the estimates indicates that conflict stands can be identified by means of laser scanning. The study also shows that it is difficult to estimate the stem numbers ha-1, the function had an R2-adj of 10.7 % and a SD of 7352 stems ha-1.Intresset för skörd av skogsbränsle i så kallade konfliktbestånd har ökat under de senaste åren som en konsekvens av det ökade behovet av biobränsle. Konfliktbestånd är ungskogar som inte har röjts och har därför många träd ha-1 med en stor höjd- och diameterspridning. Det gör att traditionella fältmätningar i konfliktbestånd är svåra och väldigt tidskrävande. Därför är skogsbruket i behov av nya effektivare inventeringsmetoder. I den här studien användes Lidar-data från Lantmäteriets nya nationella höjdmodell (NNH) i kombination med provytor från Riksskogstaxeringen år 2009 för att skapa funktioner för höjd, volym, diameter och stamantal. Dessa användes sedan för att skapa raster som motsvarade de skattade variablerna. Genom att använda kriterier för höjd, volym och diameter låg dessa raster till grund för identifieringen av konfliktbestånd. I studien användes 112 provytor för att skatta grundytevägd medelhöjd (Hgv). Vid skattningen för volym, brösthöjdsdiameter (Dbh) och stamantal användes efter stratifiering baserad på Hgv (<12 m) 33 provytor. Resultaten visar att funktionen för Hgv hade en korrigerad förklaringsgrad (R2-adj) på 92 % och en standardavvikelse (SD) på 1,4 m. Volym och Dbh hade en R2-adj på 88,2 % respektive 75,6% samt en SD på 11,5 m3sk ha-1 och 15,3 mm. Studien visade även att det är svårt att skatta stamantal, funktionen hade en R2-adj på 10,7 % och en SD på 7352 stammar ha-1. Den höga noggrannheten i skattningarna indikerar att konfliktbestånd kan identifieras med hjälp av laserskanning

Sport as a Context for Integration: Newly Arrived Immigrant Children in Sweden Drawing Sporting Experiences

Abstrac

What did they learn in school today? A method for exploring aspects of learning in physical education

What did they learn in school today?: A method for exploring aspects of learning in physical education. Abstract This paper outlines a method for exploring learning in educational practice. The suggested method combines an explicit learning theory with robust methodological steps in order to explore aspects of learning in school physical education. The design of the study is based on sociocultural learning theory, and the approach adds to previous research within the field, both in terms of the combination of methods used and the claims made in our studies. The paper describes a way of collecting and analysing the retrieved data and discusses and illustrates the results of a study using this combination of explicit learning theory and robust methodological steps. European Physical Educatio

Metabolic effects of exercise in patients with type IV hyperlipoproteinemia

Metabolic responses to 30 minutes of submaximal exercise were investigated in 11 healthy control subjects and 6 patients with type IV hyperlipoproteinemia (endogenous or essential hypertriglyceridemia). All subjects were male and ranged in age from 35 to 55 years. Before exercise they fasted overnight for at least 12 hours.The relative work performed, judged by the levels in heart rate and cardiac output on exercise, was comparable in the two groups, and the effects of exercise were qualitatively similar. Plasma glucose and triglyceride levels showed little change. Plasma concentration of cholesterol increased at the end of exercise by approximately 13 percent above control values compared to a concomitant increase in hematocrit of 3 percent. Plasma free fatty acid levels fell as exercise started and then returned to normal valves at the end of the 30 minutes of exercise; they then increased markedly after exercise but returned subsequently to control levels after 45 minutes.In response to muscular exercise, therefore, both control subjects and patients with type IV hyperlipoproteinemia significantly increase plasma cholesterol concentration. Subjects with hyperlipoproteinemia appear to mobilize free fatty acids in a normal manner for energy purposes, and the excess release of free fatty acids during exercise is apparently not derived from the abundantly circulating triglycerides; the latter were not altered by submaximal exercise.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32754/1/0000123.pd

There are some things we learned - that we hadn´t thought of : experience of and learning in the subject of physical education and health from a student perspective

Physical education and health [PEH] is a popular school subject, but the aims and purposes of the subject are not so evident. How do the students experience the subject? In this study ten female students who passed their mandatory PEH program are interviewed regarding how they experienced the subject and what they learned after twelve years of mandatory lessons in PEH. The interviews are analysed using Merleau-Ponty’s (1997) theory of the lived body. The results show that PEH is experienced as two distinct subjects: physical education and health education. The physical education part is mainly sport activities and is considered not serious, in comparison with club sports. Health education is taught as a theoretical subject and is rejected because theory does not belong to PEH. When the subject is taught in a dualistic knowledge tradition, the learning of PEH is neither theoretically nor practically satisfactory. The students vaguely suggest a more integrated approach to learning

Att samverka eller..? : Om idrottslärare och idrottsämnet i den svenska grundskolan

The subject of physical education is viewed as being in a crisis, since the pace given for it in the schedule of classes for the compulsary school has been reduced with introduction of the most recent curriculum, Lpo 94. Researchers believe that collaboration would strengthen the position of the subject and of the in the physical education teachers in school and lead to a solution of the crisis. The purpose of this dissertation is to describe, analyze, and understand against this background experiences reported by physical education teachers of collaboration between the subject of physical education and other subjects in the compulsary school in order to be able to discuss the question as to whether collaboration can strengthen the position of the subject of physical education in the school and be asolution to what is called a crisis of the subject of physical education. The approach to the research includes a number of constituent studies, where an interview study of 30 teachers in the subject of physical education constitutes the main body of the dissertation. Basil Bernstein's concept of classification defines whether collaboration between subjects and teachers occurs or not. The concept of integrated code has defined the prevailing development in the school that includes collaboration among both subjects and teachers. The result shows that collaboration is not a general solution to the crisis in the subject of physical education. One type of collaboration can make more difficult another type of collaboration. Six different categories of collaboration in working groups involving physical education teachers have been defined. The different categories emerge as a result of the culture of the school, and the professional identity of the physical education teacher at the individual schools. Most teachers in the study work under the collection code. A group of teachers of several subjects are on their way toward integrated code but the subject of physical education is not part of the collaboration in any of the categories. Collaboration in itself has no great significance according to the results for the position of the subject of physical education in the schools as the subject mainly works under collection code. And even if the physical education teachers who collaborate in working groups have a strong position, it is rather an expression of the fact that they participate in the prevailing development in the school, where collaboration is one part, than collaboration by itself. The question is also whether there is a crisis during development in the schools toward integrated code. The physical education teachers need to discuss the content of the integrated code and its application to teaching in order to avoid future crises

I want to learn without knowing that I am learning

Godkänd; 2011; 20110818 (ysko)</p

Friendship and competition : teenage girls' experiences of organised sport

Background: Organised sport is the most common leisure activity among Swedish children and youth. One of the aims of organised sport is to teach the participants how their body function and how they can acquire a healthy lifestyle. Engström (1999) argues however that the connection between participation in organised sport and a lifelong healthy lifestyle is not self evident. There are other criteria that are more important for the continuation of physical activity.Objectives: The aim of this study is to describe and understand ten female teenagers’ lived experience of organised sport and what role movement plays in their current lifeworld.Methods: Ten female teenagers, with a broad experience of organised sport, that had been playing in he same team for many years were interviewed about their experiences of sports and their notion of the body and physical activity. The interviews analysed with the help of lifeworld phenomenology (van Manen, 1990) and the theory of the lived body as an undivided unit (Merleau-Ponty,1997).Results: Three different themes appeared in the interviews:“Friendship and competition”: were important values for participating in the team.“Pushes and rewards”: were important stimulus for the choice of activity and the development of necessary skills.“Sport girl and life enjoyer”: are metaphors used for describing their relation to sport and physical activity.Conclusion: The paper will describe and discuss the differences in the respondants lived experiences from organised sport and the role sport and movement play in their current lifeworld respectively by drawing on Merleau-Ponty and lifeworld phenomenology.References: Engström, L-M.(2009).Idrott som social markör. Stockholm:HLS.Merleau-Ponty,M.(1997). Kroppens fenomenologi. Daidalos.vanManen,M. (1990).Researching lived experience. The State University New York.Godkänd; 2011; 20110629 (inka)</p