Providing efficient data transport is one of the uppermost objectives in the design of wireless sensor networks (WSNs) since the primary role for each sensor is to report the sensed data to the data sink(s). This thesis focuses on designing efficient data transport schemes for WSNs in the dimensions of energy consumption and time respectively. The developed schemes can be directly applied in a number of applications such as intrusion detection, target tracking, environment monitoring, etc., and can be further extended to underwater acoustic sensor networks and unmanned aerial vehicles (UAVs) networks. With the development of WSN technologies, new challenging research problems such as real-time streaming data gathering and intelligent data communication are emerging. This thesis provides useful foundation for designing next-generation data transport schemes for WSNs. Energy is the most important resource in WSNs because sensor nodes are commonly powered by small batteries, and energy is directly related to the lifetime of nodes and the network. In this thesis, energy-efficient data transport schemes are designed for two major types of WSNs: event-driven sensor networks and time-driven sensor networks. A novel on-line routing scheme called EBGR (Energy-efficient Beaconless Geographic Routing) is designed for event-driven sensor networks characterized by dynamic network topology. The main advantage of EBGR is that it can provide energy-efficient sensor-to-sink routing without any prior neighborhood knowledge. Moreover, the total energy consumption for sensor-to-sink data delivery under EBGR has an upper bound. Time-driven sensor networks, in which all sensors periodically report the sensed data to the sink(s), have been widely used for environment monitoring applications. Unbalanced energy consumption is an inherent problem in time-driven sensor networks. An efficient data gathering scheme, called EBDG (Energy-Balanced Data Gathering), is designed to balance energy consumption for the goal of maximizing network lifetime. Combing all advantages of corona-based network division,mixed-routing and data aggregation, EBDG can prolong network lifetime by an order of magnitude compared with conventional schemes. Time-efficient data transport is another critical issue in WSNs since the data generated by the sensor nodes may become outdated after a certain time interval. This thesis focuses on the problem of providing real-time data gathering in time-driven sensor networks. A novel data gathering scheme based on random access is proposed with the objective to minimize the average duration for completing one round of data gathering. Fully localized solutions have been designed for both linear networks and tree networks. A simple data gathering protocol called RADG (Random Access Data Gathering) is designed. Simulation results show that RADG outperforms CSMA based schemes when the size of the data packets is small. / Thesis (Ph.D.) -- University of Adelaide, School of Computer Science, 2009

Os reservatórios urbanos estão suscetíveis a uma variedade de interferências antropogênicas que acarretam grande variabilidade espacial e temporal. Contudo, possuem uma dinâmica própria na qual o hidroclima e micro e macro-eventos meteorológicos atuam sobre os processos físicos, químicos e biológicos resultando em respostas particulares de cada corpo de água. No presente estudo a existência de padrões espaciais e temporais na formação de florescimentos de algas, cianobactérias e macrófitas no reservatório Guarapiranga, São Paulo, SP, foi avaliada por meio de experimento de curta escala de tempo durante o evento da entrada de uma frente fria. Foram amostrados 64 pontos em todo o reservatório, e o estudo intensivo de florescimento algal e de cianobactérias em dois ciclos nictemerais, em um ponto selecionado no reservatório. Um modelo tridimensional de hidrodinâmica foi aplicado ao estudo compartimentalizado dos tempos de residência e imagens de satélite foram analisadas para determinação de padrões temporais e espaciais durante períodos de tempo mais amplos. Os resultados revelaram que os períodos mais favoráveis ao surgimento de florescimentos de cianobactérias são geralmente os meses mais quentes, de dezembro e janeiro, ou aqueles em que ocorrem estratificações mais fortes como no fim do inverno, em julho, e após as primeiras chuvas nos meses de setembro e outubro. Existem padrões espaciais recorrentes na formação dos florescimentos, controlados em grande parte pela ação do vento, que no reservatório Guarapiranga é predominantemente nas direções leste e sudeste empurrando os florescimentos na direção da foz dos tributários Embu Mirim e Embu Guaçu e ocasionalmente na direção da foz do rio Parelheiros. As simulações hidrodinâmicas evidenciam as forçantes que determinam os padrões observados e reforçam a importância de se discretizarem os tempos de residência de diferentes compartimentos do reservatório. As séries temporais amplas permitiram a determinação da qualidade da água em cada região e fornecem subsídios para o futuro manejo do reservatório. Como esse comportamento não se restringe ao reservatório Guarapiranga, o tipo de modelagem aqui utilizada pode ser útil para obter informações importantes no processo de planejamento e seleção de medidas para o gerenciamento de reservatórios urbanos tropicais polimíticos, em geral. / Urban reservoirs are susceptible to a variety of anthropogenic interferences, that leads to large spatial and temporal variability, however they have themselves a proper dynamics in which the hydroclimate and micro and macro meteorological events act upon physical, chemical and biological processes, resulting in a singular signature for each water body. In the present study the existence of spatial and temporal patterns for the formation of algal, cyanobacterial and macrophyte blooms in Guarapiranga Reservoir, São Paulo, SP, was evaluated by means of a short-time scale experiment during the event of a cold front passage. Sampling was carried out in 64 points in the whole reservoir and the intensive study of an algal and cyanobacterial during two nictemeral cycles, at a selected point in the reservoir. A tri-dimensional hydrodynamics model was applied to the study of discrete residence time of the main reservoir tributaries. Satellite images and long term data sets were analyzed aiming to determine spatial and temporal patterns at long time scale. The results obtained have shown that the most favorable periods for algal and cyanobacterial blooms are usually the hottest months, December and January, or those with stronger thermal stratification at the end of the winter in July and after the first rains in September and October months. There are recurrent spatial patterns in the formation of blooms, largely controlled by wind action, that in Guarapiranga Reservoir are predominantly from East and Southeast directions frequently pushing the blooms towards Embu Mirim and Embu Guaçu tributaries and occasionally towards Parelheiros River mouth. Hydrodynamic simulations evidenced the forcing functions that control the observed patterns and reinforced the importance of residence time discretization according to each main reservoir compartment. The temporal data series allowed to assess each compartment water quality and provided information for future reservoir management. Considering that the patterns found are not restricted to Guarapiranga Reservoir, the type of model here used could be useful to get relevant information to be used in the planning or selection of management actions for tropical polymictic urban reservoirs in general.

Den ökade globaliseringen har främjat utrikeshandeln. Vidare har de minskaderestriktionerna och handelshindren medfört att företag numera är verksamma på en global och turbulent marknad. Syftet med denna studie är att jämföra Sverige och Kina medavseende på utrikeshandel och hinder. Inom utrikeshandeln är hinder i samband medgodstransport ett vanligt förekommande problem av den anledningen kommer dessahinder analyseras och studeras. Sverige har valts att undersökas för att tillföra ett svensktperspektiv och bidra till en ökad insikt inom svensk utrikeshandel. Kina har valts attundersökas eftersom det är en ekonomisk världsledande nation inom utrikeshandeln.Vidare har forskningsfrågor formulerats och dessa har besvarats med hjälp avtillhandahållen data av Världsbankens enkätundersökning. Den erhållna datan harbearbetats och analyserats med hjälp av envariabels- och flervariabelanalys som harbehandlats av statistikprogrammet Statistical Package for the Social Sciences (SPSS). Iden teoretiska referensramen har data samlats in genom kurslitteratur, vetenskapligaartiklar och webbkällor. I resultatavsnittet har tabeller och diagram upprättats för att åskådliggöra skillnader mellan Sveriges och Kinas utrikeshandel och hinder med avseende på export, import, stöld, skadat gods, och transporttid. Av resultatet framgår det att andelen importeratmaterial och råvaror anges vara dubbelt så stor i Sverige i jämförelse med Kina. I slutsatsen framgår det att finns markanta skillnader mellan Sverige och Kina gällandeländernas utrikeshandel och hinder. Vidare har förbättringsåtgärder och lösningarpresenterats med teorin som utgångspunkt. Några av dessa innefattar implementering aveffektiviserade och optimerade distributionssystem och utformningen av hållbara ochsäkra godsförpackningar för att minska förekomsten av skadat gods under transport. Denna studie behandlar ett nytt forskningsområde och kommer huvudsakligen tillföra nykunskap inom Sveriges och Kinas utbyteshandel och hinder i samband med godstransportvilket är ett aktuellt fenomen med hög relevans. Med hjälp av aktuell forskning kanförekommande hinder i samband med godstransport analyseras och förebyggas.

Os reservatórios urbanos estão suscetíveis a uma variedade de interferências antropogênicas que acarretam grande variabilidade espacial e temporal. Contudo, possuem uma dinâmica própria na qual o hidroclima e micro e macro-eventos meteorológicos atuam sobre os processos físicos, químicos e biológicos resultando em respostas particulares de cada corpo de água. No presente estudo a existência de padrões espaciais e temporais na formação de florescimentos de algas, cianobactérias e macrófitas no reservatório Guarapiranga, São Paulo, SP, foi avaliada por meio de experimento de curta escala de tempo durante o evento da entrada de uma frente fria. Foram amostrados 64 pontos em todo o reservatório, e o estudo intensivo de florescimento algal e de cianobactérias em dois ciclos nictemerais, em um ponto selecionado no reservatório. Um modelo tridimensional de hidrodinâmica foi aplicado ao estudo compartimentalizado dos tempos de residência e imagens de satélite foram analisadas para determinação de padrões temporais e espaciais durante períodos de tempo mais amplos. Os resultados revelaram que os períodos mais favoráveis ao surgimento de florescimentos de cianobactérias são geralmente os meses mais quentes, de dezembro e janeiro, ou aqueles em que ocorrem estratificações mais fortes como no fim do inverno, em julho, e após as primeiras chuvas nos meses de setembro e outubro. Existem padrões espaciais recorrentes na formação dos florescimentos, controlados em grande parte pela ação do vento, que no reservatório Guarapiranga é predominantemente nas direções leste e sudeste empurrando os florescimentos na direção da foz dos tributários Embu Mirim e Embu Guaçu e ocasionalmente na direção da foz do rio Parelheiros. As simulações hidrodinâmicas evidenciam as forçantes que determinam os padrões observados e reforçam a importância de se discretizarem os tempos de residência de diferentes compartimentos do reservatório. As séries temporais amplas permitiram a determinação da qualidade da água em cada região e fornecem subsídios para o futuro manejo do reservatório. Como esse comportamento não se restringe ao reservatório Guarapiranga, o tipo de modelagem aqui utilizada pode ser útil para obter informações importantes no processo de planejamento e seleção de medidas para o gerenciamento de reservatórios urbanos tropicais polimíticos, em geral. / Urban reservoirs are susceptible to a variety of anthropogenic interferences, that leads to large spatial and temporal variability, however they have themselves a proper dynamics in which the hydroclimate and micro and macro meteorological events act upon physical, chemical and biological processes, resulting in a singular signature for each water body. In the present study the existence of spatial and temporal patterns for the formation of algal, cyanobacterial and macrophyte blooms in Guarapiranga Reservoir, São Paulo, SP, was evaluated by means of a short-time scale experiment during the event of a cold front passage. Sampling was carried out in 64 points in the whole reservoir and the intensive study of an algal and cyanobacterial during two nictemeral cycles, at a selected point in the reservoir. A tri-dimensional hydrodynamics model was applied to the study of discrete residence time of the main reservoir tributaries. Satellite images and long term data sets were analyzed aiming to determine spatial and temporal patterns at long time scale. The results obtained have shown that the most favorable periods for algal and cyanobacterial blooms are usually the hottest months, December and January, or those with stronger thermal stratification at the end of the winter in July and after the first rains in September and October months. There are recurrent spatial patterns in the formation of blooms, largely controlled by wind action, that in Guarapiranga Reservoir are predominantly from East and Southeast directions frequently pushing the blooms towards Embu Mirim and Embu Guaçu tributaries and occasionally towards Parelheiros River mouth. Hydrodynamic simulations evidenced the forcing functions that control the observed patterns and reinforced the importance of residence time discretization according to each main reservoir compartment. The temporal data series allowed to assess each compartment water quality and provided information for future reservoir management. Considering that the patterns found are not restricted to Guarapiranga Reservoir, the type of model here used could be useful to get relevant information to be used in the planning or selection of management actions for tropical polymictic urban reservoirs in general.

This study aims to explore effectiveness within intermodal transportation of semi-trailers based on the variables cost and time. Intermodal transport can be explained as a transportation of a carrier, from the origin to the final destination, using two or more modes of transport (Crainic & Kim, 2007 p.467). This study focuses on the two modes of transport rail and road. The rail transportation has big advantages towards other modes of transport since it has less impact on the environment, given that the energy is produced in Sweden (Trafikverket 2017) but there are more benefits to be utilized. The rail transportation is generally more profitable on distances greater than 500 km, thus it can transport high volumes of goods over long distances for a low cost. The fixed costs that´s added in the terminals and the rail transports low degree of flexibility compared to the road transport is the primary reasons why rail transportation isn´t profitable on shorter distances. This study has made a market research to see where the final destinations for the imported semi-trailers are located in Sweden and Norway. This, to see where there are potential to develop and create new rail shuttles from Port of Gothenburg to dry ports across the Swedish and Norwegian inland for transportation of semi-trailers. Interviews have been conducted with carriers to create a more correct view of the current situation. Study results show that the greatest volumes of the transported semi-trailers ends up in the areas around Helsingborg and Stockholm, with the region around Gothenburg excluded. Dry ports positioned in this area show the best potential for development of new rail shuttles. The results from conducted interviews with carriers express that time is the most important aspect for their operation and their clients, that is also the reason why they don´t use the railway for transportation of semi-trailers. Carriers also consider the trains to be unreliable and the railway operation in Port of Gothenburg has so far not been operating well enough for them. The result show that 38 percent of the imported semi-trailers have their final destination in the area around Gothenburg and naturally it´s not possible for the railway to compete with the road transport at such a short distance. In order for the railway to compete with the road transport, rail shuttles to regions with high flows of semi-trailers must be developed to not loose in time and flexibility. Thus, the railway transportation has other opportunities than just transportation. In dry ports there are opportunities for storage of goods, which is generally cheaper than in the port and simultaneously create time gains in the final transportation, thus the goods are closer to the customer. Port of Gothenburg can compete with other ports, which are geographically closer to a certain customer, through more rail shuttles with more frequent departures and then take more market shares within Nordic transportation. / Studien syftar till att undersöka transporteffektiviteten för intermodala transporter av semitrailrar med utgångspunkt från variablerna kostnad och tid. Intermodala transporter kan förklaras som en transport av en lastbärare från dess ursprung till dess slutdestination med hjälp av två eller flera olika transportsätt (Crainic & Kim, 2007 s.467) och denna studie fokuserar på de två transportsätten järnväg och väg. Just järnvägstransporten har en stor fördel gentemot andra transportsätt då det är ett mer miljövänligt alternativ, förutsatt att det är eldrivna tåg samt att elen är producerad i Sverige (Trafikverket 2017) men det finns även fler fördelar som kan utnyttjas. Järnvägstransporten är generellt lönsammare på avstånd längre än 500 km, då det kan transportera stora volymer över långa avstånd till en låg kostnad. Varför det inte är lönsamt på kortare sträckor beror framför allt på de fasta avgifter som tillkommer vid terminalerna och järnvägens relativt låga flexibilitet gentemot vägtransporten. Studien har gjort en marknadsundersökning för att se var de importerade semitrailrarna har sin slutdestination inom Sverige och Norge. Det för att se var det finns potential för att utveckla och skapa nya järnvägspendlar från Göteborgs Hamn till torrhamnar för transport av semitrailrar via järnväg. Intervjuer har utförts med speditörer i anslutning till hamnen för att skapa en så bra bild som möjligt av nuläget. Resultatet visar att de största volymerna i flödet av semitrailrar går till Helsingborg och Stockholm med omnejd, med Göteborg exkluderat. Det är de två områdena som visar potential för att eventuellt skapa järnvägspendlar till torrhamnar. Vid intervjuerna som utförts uttrycker speditörerna att tid är den viktigaste aspekten för deras verksamhet och kunder. Det är även anledningen till att de inte använder sig av järnvägstransport för semitrailrar, då tågen är för opålitliga och verksamheten för järnvägstransport kring Göteborgs Hamn inte har fungerat för dem hitintills. Resultatet visar även att drygt 38 procent av de importerade semitrailrarna har sin slutdestination i Göteborgsområdet och där kan naturligtvis inte järnvägstransporten konkurrera med vägtransporten på grund av det korta avståndet. För att järnvägstransporten ska kunna konkurrera med vägtransporten måste det skapas pendlar till de regionerna med större flöden för att inte förlora tid och flexibilitet gentemot vägtransporten. Dock så ger järnvägstransporten andra möjligheter än bara transport av gods. I torrhamnarna finns möjligheter för lagring av gods, som generellt är billigare än lagring i hamnen och ger samtidigt tidsvinster när den slutliga transporten till kund ska utföras, då godset är närmare kunden. Göteborgs Hamn kan konkurrera med andra hamnar som geografisk ligger närmare en viss kund, genom att fler järnvägspendlar med frekventare avgångar kan skapas och på så sätt ta marknadsandelar inom nordisk transport.