Distance measure and the p-median problem in rural areas

The p-median model is used to locate P facilities to serve a geographically distributed population. Conventionally, it is assumed that the population patronize the nearest facility and that the distance between the resident and the facility may be measured by the Euclidean distance. Carling, Han, and Håkansson (2012) compared two network distances with the Euclidean in a rural region witha sparse, heterogeneous network and a non-symmetric distribution of thepopulation. For a coarse network and P small, they found, in contrast to the literature, the Euclidean distance to be problematic. In this paper we extend their work by use of a refined network and study systematically the case when P is of varying size (2-100 facilities). We find that the network distance give as gooda solution as the travel-time network. The Euclidean distance gives solutions some 2-7 per cent worse than the network distances, and the solutions deteriorate with increasing P. Our conclusions extend to intra-urban location problems.

Movements and mechanical stresses in gas-filled flat plate solar collectors

Sealed gas filled flat plate solar collectors will have stresses in the material since volume and pressure varies in the gas when the temperature changes. Several geometries were analyzed and it could be seen that it is possible reducing the stresses and improve the safety factor of the weakest point in the construction by using larger area and/or reducing the distance between glass and absorber and/or change width and height relationship so the tubes are getting longer. Further it could be shown that the safety factor won't always get improved with reinforcements. It is so because when an already strong part of the collector gets reinforced it will expose weaker parts for higher stresses. The finite element method was used for finding out the stresses.

Långa toppar - metod för uttag av skogsbränsle i slutavverkningar : Slutrapport (STEM-projekt 21937-1)

SammanfattningHögskolan Dalarna har i samarbete med Skogsägarna Mellanskog, Naturbränsle i Mellan¬sverige AB och GDE-Net genomfört studier på en ny metod för uttag av skogsbränsle från slutavverkningar. Metoden går ut på att timmer tas ut som enda rundvirkessortiment. Resten av trädet, samt klenare träd som inte håller timmerdimension, tas ut som ett bränslesortiment. Metoden har jämförts med en konventionell slutavverkning med uttag av timmer, massaved och GROT-flis.Enligt genomförda försök skulle en avverkning enligt den nya metoden (långa toppar) ge ett högre drivningsnetto och drygt dubbelt så mycket bränsleflis som en konventionell avverk¬ning. En anledning till det högre drivningsnettot är att kostnaden för flisning blir lägre än vid flisning av GROT och att flisen betalas bättre än GROT-flis. Resultaten är beroende av de faktiska beståndsförutsättningarna och gällande prisrelationer mellan massaved och bränsle¬flis.Faktorer som har en positiv inverkan på drivningsnettot vid uttag av ”långa toppar” är t.ex. stora uttagsvolymer och korta terrängtransportavstånd samt bestånd med en hög andel virke av låg kvalitet eller udda sortiment som betalas dåligt på rundvirkesmarknaden.SummaryIn Sweden forest energy from final felling is traditionally harvested as logging residues after harvesting of timber (saw logs) and pulpwood, but depending on the market situation other methods with higher yield of forest energy might be of interest. Dalarna University has study a new method called “Undelimbed long tops” where only saw timber was taken out as an industrial assortment. The rest of the trees and smaller trees that don’t hold timber dimensions was left intact on the clear-felled area and been chipped later on. The study was done in different stands with some different conditions. The results have been compared with the traditional method for final felling. The surplus (forest owners net income) was higher in almost all stands when the method with “undelimbed long tops” was used, compared to the traditional method for taking out forest energy, and the volume of chips was more than doubled. A reason for the higher income from long tops is that the costs for chipping is lower and the prize of chips is higher compared to chips from logging residues. Other reason is that forest owners will not be paid for wasted pulpwood, but will be fully paid for the chips from such pulpwood. Factors that will have a positive influence on the ULT-method are for example large logging volumes and short distance between the logging area and the landing, different kinds of price reductions on pulpwood and large volumes of rotten wood or low paid industrial assortments.

A Computer Vision Framework For Finger-Tapping Evaluation In Parkinson's Disease

Objective: To define and evaluate a Computer-Vision (CV) method for scoring Paced Finger-Tapping (PFT) in Parkinson's disease (PD) using quantitative motion analysis of index-fingers and to compare the obtained scores to the UPDRS (Unified Parkinson's Disease Rating Scale) finger-taps (FT). Background: The naked-eye evaluation of PFT in clinical practice results in coarse resolution to determine PD status. Besides, sensor mechanisms for PFT evaluation may cause patients discomfort. In order to avoid cost and effort of applying wearable sensors, a CV system for non-invasive PFT evaluation is introduced. Methods: A database of 221 PFT videos from 6 PD patients was processed. The subjects were instructed to position their hands above their shoulders besides the face and tap the index-finger against the thumb consistently with speed. They were facing towards a pivoted camera during recording. The videos were rated by two clinicians between symptom levels 0-to-3 using UPDRS-FT. The CV method incorporates a motion analyzer and a face detector. The method detects the face of testee in each video-frame. The frame is split into two images from face-rectangle center. Two regions of interest are located in each image to detect index-finger motion of left and right hands respectively. The tracking of opening and closing phases of dominant hand index-finger produces a tapping time-series. This time-series is normalized by the face height. The normalization calibrates the amplitude in tapping signal which is affected by the varying distance between camera and subject (farther the camera, lesser the amplitude). A total of 15 features were classified using K-nearest neighbor (KNN) classifier to characterize the symptoms levels in UPDRS-FT. The target ratings provided by the raters were averaged. Results: A 10-fold cross validation in KNN classified 221 videos between 3 symptom levels with 75% accuracy. An area under the receiver operating characteristic curves of 82.6% supports feasibility of the obtained features to replicate clinical assessments. Conclusions: The system is able to track index-finger motion to estimate tapping symptoms in PD. It has certain advantages compared to other technologies (e.g. magnetic sensors, accelerometers etc.) for PFT evaluation to improve and automate the ratings

How initial vocational education and training (IVET) teachers in Sweden perceive their prospects of being able to prepare upper secondary school pupils for a future occupation

Vocational teachers in Swedish upper secondary schools are a heterogeneous category of teachers, connected to different types of trade. These teachers represent a broad set of trade skills varying in content and character. In their teacher role, they continue to wear the clothes, speak the language, share the culture and remain mentally in their former professions. Still, it is central that they keep up this contact to be able to school the pupils into the environment of the trade in question, but also to help them to understand what skills a profession demands. However, the individual teacher also has to distance himself from the negative elements in the culture of the profession: patterns and habits that, for various reasons, have to be broken or changed. This paper draws attention to the ways in which a group of vocational teachers, who were participants in a project that aimed to train unauthorized vocational teachers, expressed their ambitions to prepare the pupils for a future professional career. When collecting information, we used the degree dissertations they produced and discussed in seminars, and informal dialogues. The result shows that it is important that the instruction location resembles a real working site as far as possible. These places are more or less realistic copies of a garage, a restaurant kitchen, a hairdressing salon, and so on, in order to give the pupils a realistic setting for instruction. However, the fact that these simulated workplaces lack the necessary support functions that exist in a company creates problems, problems which make a lot of extra work for the teachers. Vocational teachers also have to instruct the pupil in the experienced practitioner’s professional skills and working situation, but the pupil herself/himself must learn the job by doing it in practice. Some vocational upper secondary programs lack relevant course literature and the businesses give little support. This also makes extra work for the teachers. Moreover, the distance between the vocational programs and the trainee jobs was experienced as being difficult to overcome. One reason seems to be differences between businesses and differing preconditions between small and big companies’ abilities to take care of these pupils. The upper secondary school vocational programs also play a role in cementing existing gender roles, as well as perpetuating class-related patterns on the labour market.

How initial vocational education and training (IVET) teachers in Sweden perceive their prospects of being able to prepare upper secondary school pupils for a future occupation

Vocational teachers in Swedish upper secondary schools are a heterogeneous category of teachers, connected to different types of trade. These teachers represent a broad set of trade skills varying in content and character. In their teacher role, they continue to wear the clothes, speak the language, share the culture and remain mentally in their former professions. Still, it is central that they keep up this contact to be able to school the pupils into the environment of the trade in question, but also to help them to understand what skills a profession demands. However, the individual teacher also has to distance himself from the negative elements in the culture of the profession: patterns and habits that, for various reasons, have to be broken or changed. This paper draws attention to the ways in which a group of vocational teachers, who were participants in a project that aimed to train unauthorized vocational teachers, expressed their ambitions to prepare the pupils for a future professional career. When collecting information, we used the degree dissertations they produced and discussed in seminars, and informal dialogues. The result shows that it is important that the instruction location resembles a real working site as far as possible. These places are more or less realistic copies of a garage, a restaurant kitchen, a hairdressing salon, and so on, in order to give the pupils a realistic setting for instruction. However, the fact that these simulated workplaces lack the necessary support functions that exist in a company creates problems, problems which make a lot of extra work for the teachers. Vocational teachers also have to instruct the pupil in the experienced practitioner’s professional skills and working situation, but the pupil herself/himself must learn the job by doing it in practice. Some vocational upper secondary programs lack relevant course literature and the businesses give little support. This also makes extra work for the teachers. Moreover, the distance between the vocational programs and the trainee jobs was experienced as being difficult to overcome. One reason seems to be differences between businesses and differing preconditions between small and big companies’ abilities to take care of these pupils. The upper secondary school vocational programs also play a role in cementing existing gender roles, as well as perpetuating class-related patterns on the labour market.