255 research outputs found
Kiertovaihtoalgoritmi ja muunnoksia yleistetylle ajoneuvoreititysongelmalle
Vehicle routing problems have numerous applications in ïŹelds such as transportation, supply logistics and network design. The optimal design of these routes fall in the category of NP-hard optimization problems, meaning that the computational complexity increases extremely fast with increasing problem size.
The Generalized Vehicle Routing Problem (GVRP) is a general problem type that includes a broad variety of other problems as special cases. The main special feature of the GVRP is that the customers are grouped in clusters. For each cluster, only one customer is visited.
In this thesis, we implement a heuristic algorithm to solve GVRP instances in reasonable time. Especially, we include a cyclic exchange method that considers a very large search neighborhood.
In addition, we study the related Capacitated m-Ring-Star Problem (CmRSP). We present the Distance-Constrained Capacitated m-Ring-Star Problem (DCmRSP) and show that it contains the Multivehicle Covering Tour Problem (MCTP) as a special case. We show that DCmRSP instances can be transformed to (distance-constrained) GVRP with minor adaptations and solved with the same heuristic algorithm.
Our algorithm is able to ïŹnd best known solutions to all GVRP test instances; for two of them, our method shows strict improvement. The transformed CmRSP and MCTP instances are solved successfully by the same algorithm with adequate performance.Ajoneuvoreititysongelmilla on lukuisia sovelluksia muun muassa logistiikan ja verkostosuunnittelun aloilla. TĂ€llaisten reittien optimaalinen ratkaiseminen kuuluu NP-vaikeiden optimointiongelmien kategoriaan, eli ratkaisuun vaadittava laskentateho kasvaa erittĂ€in nopeasti ongelman koon suhteen.
Yleistetty ajoneuvoreititysongelma (Generalized Vehicle Routing Problem, GVRP) on ongelmatyyppi, joka kattaa joukon muita reititysongelmia erikoistapauksina. GVRP:n selkein erityispiirre on asiakkaiden jako ryppÀisiin: kussakin ryppÀÀssÀ on kÀytÀvÀ tasan yhden asiakkaan luona.
TÀssÀ diplomityössÀ esitellÀÀn ja toteutetaan heuristinen algoritmi, joka etsii kohtalaisessa ajassa ratkaisuja GVRP-ongelmiin. MenetelmÀ sisÀltÀÀ kiertovaihtoalgoritmin, joka kykenee etsimÀÀn ratkaisuja hyvin laajasta ympÀristöstÀ.
Tutkimuksen kohteena on lisÀksi m-rengastÀhtiongelma (Capacitated m-Ring-Star Problem, CmRSP). Esittelemme ongelman etÀisyysrajoitetun version (DCmRSP), ja nÀytÀmme, ettÀ kyseiseen ongelmaan sisÀltyy usean ajoneuvon peittÀvÀn reitin ongelma (Multivehicle Covering Tour Problem). NÀytÀmme, ettÀ DCmRSP-ongelman pystyy pienin muutoksin muuntamaan GVRP-ongelmaksi ja ratkaisemaan samalla heuristisella algoritmilla.
Algoritmi löytÀÀ parhaat tunnetut ratkaisut kaikkiin GVRP-testitehtÀviin. Kahdessa tapauksessa ratkaisu on parempi aiemmin löydettyihin nÀhden. Algoritmi kykenee ratkaisemaan muunnetut CmRSP- ja MCTP-testitehtÀvÀt kohtalaisella ratkaisulaadulla
Studerandes förklaringsmodeller gÀllande glödlampors ljusstyrka i likströmskretsar
Studerandes begreppsförstÄelse Àr av stort intresse inom fysikundervisningen. Inte minst eftersom slutprov och eventuella förhör ofta Àmnar att summativt bedöma just denna begreppsförstÄelse. De olika fysikaliska begreppen förekommer dock inte som frÄn varandra isolerade entiteter, utan Àr kopplade till varandra pÄ olika sÀtt via modeller.
I den hÀr undersökningen utreds hurdana förklaringsmodeller studerande anvÀnder dÄ de förklarar glödlampors relativa ljusstyrka i likströmskretsar. Förutom sjÀlva förklaringsmodellerna sÄ undersöks Àven hur studerandes anvÀndning av förklaringsmodeller Àndras dÄ de löser samma uppgift andra gÄngen. Dessutom granskas hurdana förklaringsmodeller anvÀnds av de studerande som Àr bra pÄ att lösa de framförda likströmskretsuppgifterna.
Som grund för forskningen anvÀndes transkriberade intervjuer dÀr studerande skulle göra förutsÀgelser om likströmskretsar som presenterades för dem. Som intervjuobjekt fungerade femton (N=15) studerande pÄ Helsingfors universitet vilka alla var ÀmneslÀrarstuderande med fysik som biÀmne. Ur detta material plockades sex (N=6) studerande vilkas svar analyserades med hjÀlp av en latent innehÄllsanalys.
Totalt tretton olika förklaringsmodeller kunde urskiljas i studerandes resonemang. DÄ studerande löste samma uppgift för andra gÄngen kunde tvÄ saker observeras. Om lamporna i likströmskretsen hade samma resistans sÄ minskade de studerande i regel pÄ antalet förklaringsmodeller de anvÀnde. Men om lamporna i likströmskretsen hade olika resistans sÄ kunde motsvarande minskning inte observeras. De studerande som ofta resonerade korrekt i uppgifterna anvÀnde sig av förklaringsmodeller dÀr begreppen elektrisk effekt eller energi framkom
Vitamin C, Iron, Nitrate, and Nitrite in the Development of Islet Autoimmunity and Type 1 Diabetes : Two Prospective Birth Cohort Studies of Individuals at Increased Genetic Risk of Type 1 Diabetes
Tyypin 1 diabetes on autoimmuunisairaus, jossa elimistön puolustusjÀrjestelmÀ tuhoaa haiman insuliinia tuottavia saarekesoluja johtaen lopulta insuliinin tuotannon loppumiseen. Kun elimistö ei kykene enÀÀ sÀÀtelemÀÀn veren sokeripitoisuutta, tarvitaan hoidoksi eliniÀn kestÀvÀÀ insuliinin annostelua. Toistaiseksi ei tarkasti tiedetÀ sairastumisen syitÀ eikÀ mekanismeja, mutta tiettyjen autovasta-aineiden ilmaantuminen verenkiertoon kuvastaa beetasoluauto-immuniteetin kehittymistÀ. PerimÀ ja ympÀristötekijÀt kuten ravinto voivat vaikuttaa elimistön tulehdustekijöihin, jotka joko edistÀvÀt tai ehkÀisevÀt autoimmuunireaktion ja edelleen kliiniseen tyypin 1 diabeteksen kehittymistÀ.
VÀitöskirjatutkimuksessani selvitettiin lapsuusiÀn veren C-vitamiinipitoisuuden yhteyttÀ tyypin 1 diabeteksen kehittymiseen sekÀ muokkaavatko C-vitamiinin aineenvaihduntaa sÀÀtelevÀt genotyypit tÀtÀ yhteyttÀ. LisÀksi selvitettiin Àidin raskaudenaikaisen ravinnon C-vitamiinin, raudan, nitraatin ja nitriitin saannin yhteyttÀ tyypin 1 diabeteksen kehittymiseen.
Aineistoni kerĂ€ttiin kansainvĂ€lisestĂ€ The Environmental Determinants of Diabetes in the Young (TEDDY) (n=8,677) sekĂ€ suomalaisesta Type 1 Diabetes Prediction and Prevention (DIPP) (n=7,782) seurantatutkimuksista. Tutkimuksessa olevilla lapsilla on geneettisesti suurentunut sairastumisalttius tyypin 1 diabetekseen. Lapsilta seurattiin tyypin 1 diabetekseen liitettyjen autovasta-aineiden ilmaantumista sekĂ€ kliinisen tyypin 1 diabeteksen kehittymistĂ€ 3â12 kuukauden vĂ€lein 15-vuotiaaksi asti (DIPP) tai kunnes tyypin 1 diabetes diagnosoitiin (TEDDY). TEDDY-tutkimuksessa veren C-vitamiinipitoisuus mitattiin vuosittain 6-vuotiaaksi asti ja lapsilta kerĂ€ttiin tiedot C-vitamiinin aineenvaihduntaa sÀÀtelevistĂ€ geeneistĂ€. DIPP-tutkimuksessa Ă€itien ruoankĂ€yttötiedot mitattiin validoidulla ruoankĂ€ytön kyselylomakkeella kahdeksannen raskauskuukauden aikana, mikĂ€ kuvailee koko raskaudenaikaisetta ruoankĂ€yttöÀ. Tilastollisina analyyseinĂ€ kĂ€ytettiin Cox regressioanalyysia sekĂ€ logistista regressioanalyysia.
Veren korkea C-vitamiininpitoisuus lapsuusiĂ€ssĂ€ oli suojaavassa yhteydessĂ€ beetasolu-autoimmuniteetin riskiin. C-vitamiinin aineenvaihduntaa sÀÀtelevĂ€t genotyypit eivĂ€t muokanneet tĂ€tĂ€ yhteyttĂ€. Ăidin raskaudenaikainen C-vitamiinin, raudan, nitraatin tai nitriitin saanti ei nĂ€yttĂ€isi olevan yhteydessĂ€ lapsen beetasolu-autoimmuniteetin tai kliinisen tyypin 1 diabeteksen riskiin.
Tulokset viittaavat siihen, ettĂ€ korkea veren C-vitamiininpitoisuus varhaislapsuudessa saattaa suojata beetasolu-autoimmuniteetin kehittymiseltĂ€. Ăidin raskaudenaikaisen C-vitamiinin, raudan, nitraatin tai nitriitin saanti ei ole yhteydessĂ€ lapsen riskiin sairastua tyypin 1 diabetekseen. Ravintoaineiden tarkkaan sÀÀdelty kuljetus istukassa voi olla mahdollinen selittĂ€vĂ€ tekijĂ€.Type 1 diabetes is the result of an autoimmune reaction against insulin-producing beta cells in the pancreas, leading to the eventual termination of insulin production. Since the body can no longer control blood glucose levels, lifetime insulin therapy is required. The causes and mechanisms are still relatively unknown, but the emergence of specific autoantibodies in blood circulation signifies islet autoimmunity development. Genetics and environmental triggers, such as diet, might affect inflammation markers, which either induce or suppress autoimmune reactions and further lead to development type 1 diabetes.
The aim of this thesis was to explore whether plasma vitamin C status in childhood is associated with the risk of type 1 diabetes development and whether vitamin C metabolism-related genotypes modify the association. Furthermore, the aim was to explore whether maternal intake of vitamin C, iron, nitrate, and nitrite during pregnancy is associated with the risk of developing type 1 diabetes.
This thesis was a part of multinational The Environmental Determinants of Diabetes in the Young (TEDDY) Study (n = 8,677) and Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study (n = 7,782). The children studied carry a high or moderate genetic risk for type 1 diabetes. Children were monitored for the emergence of autoantibodies associated with type 1 diabetes and the development of clinical type 1 diabetes between 3- and 12-month intervals up to 15 years of age (DIPP) or up to the diagnosis of type 1 diabetes (TEDDY). Childhood plasma vitamin C status was measured up to 6 years of age, and the genotypes related to vitamin C metabolism were assessed in the TEDDY Study. Maternal diet was assessed using a semiquantitative validated food frequency questionnaire (FFQ) covering total diet during 8th month of pregnancy in the DIPP Study. The statistical methods used were the Cox proportional-hazards model and condition logistic regression.
Childhood plasma vitamin C status was associated with a decreased risk of islet autoimmunity. Vitamin C metabolism-related genotypes did not modify this association. Maternal intake of vitamin C, iron, nitrate, or nitrite during pregnancy was not associated with the risk of islet autoimmunity or type 1 diabetes in offspring.
The results suggest that a high plasma vitamin C status in the early childhood might protect against islet autoimmunity. Maternal intake of vitamin C, iron, nitrate, or nitrite during pregnancy was not associated with childhood type 1 diabetes development. This may result from tightly regulated nutrient transportation in the placenta
National-scale nitrogen loading from the Finnish agricultural fields has decreased since the 1990s
The national scale nutrient load modelling system VEMALA-ICECREAM was used to simulate agricultural total nitrogen(TN) loading and its trends for all Finnish watersheds for the period from 1990â2019. Across Finland, agricultural TN loading (ATNL) has decreased from 17.4 kg ha-1 a-1 to 14.4 kg ha-1 a-1 (moving 10-year averages) since the 1990s. The main driver of the decrease in simulated ATNL is a reduction in mineral fertilizer use, which has decreased the N surplus in the soils. The TN leached fraction, however, did not show a trend but did have high annual variability due to variations in runoff; this corresponds to an average of 14.4% of the TN applied. The ATNL was considerably higher in the Archipelago Sea catchment compared to other Finnish Baltic Sea sub-catchments, with the lowest ATNL found in the Vuoksi catchment in Eastern Finland. The highest decrease of ATNL was simulated for Vuoksi and Gulf of Finland catchments. In the Bothnian Sea, Bothnian Bay and Archipelago Sea catchments, the decreasing trend of ATNL was smaller but still significant, with the exception of the Quark catchment, where there was no significant change. The differences in decreasing trends between regions can be explained by the heterogeneity of catchment characteristics, hydrology and agricultural practices in different regions.
Enabling Sociability When Using Virtual Reality Applications : A Design Science Research Approach
Peer reviewe
Employing Mixed Reality Applications : Customer Experience Perspective
The study analyses twelve empirical cases employing different Mixed Reality (MR) applications: 1) 360-videos, 2) augmented reality (AR) mobile applications, 3) augmented virtuality (AV), and 4) AV+AR. The empirical data in all cases consist of observations of usersâ and potential customersâ experiences with different MR applications followed by qualitative interviews. The study assesses how various MR applications can create experience-centric services. The research focus is in service and sensory design as well as in customer experience management. The study results suggest that MR can provide new opportunities for prolonged customer experiences in terms of new encounters and cues, different sensory effects and improved social interactions among business representatives and fellow customers. Furthermore, MR experiences can generate positive word-of-mouth especially in cases with dramatic structures. Finally, the results suggest that the customers' willingness-to-interact with service personnel increase after a MR experience.The study analyses twelve empirical cases employing different Mixed Reality (MR) applications: 1) 360-videos, 2) augmented reality (AR) mobile applications, 3) augmented virtuality (AV), and 4) AV+AR. The empirical data in all cases consist of observations of usersâ and potential customersâ experiences with different MR applications followed by qualitative interviews. The study assesses how various MR applications can create experience-centric services. The research focus is in service and sensory design as well as in customer experience management. The study results suggest that MR can provide new opportunities for prolonged customer experiences in terms of new encounters and cues, different sensory effects and improved social interactions among business representatives and fellow customers. Furthermore, MR experiences can generate positive word-of-mouth especially in cases with dramatic structures. Finally, the results suggest that the customers' willingness-to-interact with service personnel increase after a MR experience.Peer reviewe
Exploring the future use of forests : perceptions from non-industrial private forest owners in Finland
The transformation of the forest sector toward a bioeconomy calls for finding new sources of competitive advantage for the whole sector to retain its future viability. Non-industrial private forest owners are an important group of actors in the Finnish forest-based sector, as they supply 80% of industrial roundwood and control numerous other tangible and intangible forest-based ecosystem services. Our study analyzes forest owner views on the future use of forests in Finland, their perceptions on the evolving sectorial interlinkages and the position of the forest sector now and in the future bioeconomy. The data were collected in two phases: through telephone interviews of forest owners (n=278) and four focus group (FG) discussions (n=17), and were analyzed both qualitatively and quantitatively. The interviews showed that forest owners consider the highest potential for strengthening the sector toward bioeconomy to come from collaboration with energy and construction businesses. During the FG phase, we identified new possibilities founded on forest-based recreational services, cooperation with nature-based tourism and in increasing value-added wood products. In total, forest owners as a high-involvement group emphasized future value creation to be based upon forest ecosystem services and in diversifying the utilization of forests beyond the dominant raw material-driven mindset.Peer reviewe
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