Denna uppsats handlar om den samtida konstnären Oh de Laval och utforskar med en semiotiskt förankrad analysmetod appropriering i två olika konstverk och samhörigheten mellan dem. Verken som analyseras i studien är Oh de Lavals, Luncheon on the grass, 2019 och Édouard Manet, Le Déjeuner sur l'herbe, 1863 och stöds av Pablo Picasso, Le Déjeuner sur l'herbe, 1959-1962. Studiens övergripande syfte undersöker hur appropriering av konst förekommer i de olika verken som analyseras samt en juridisk synvinkel kring ämnet. Studien stöds av teoretiska ramverk som inkluderar postkoloniala och feministiska perspektiv som öppnar upp frågor om ras, jämställdhet, kulturell appropriering och kvinnors representation i konsten.

Images of shop assistants - class and gender in french urban environments during the 1880’s. The aim of this study is to examine the representation of class and gender in two French paintings by Édouard-Jean Dambourgez and James Tissot from the 1880’s, depicting women working outside the home. I have examined how their roles as shop assistants are captured and if the male gaze, and subsequently the woman as an object, has any explanatory value in the paintings. The artworks were analysed using a somewhat reworked version of Erwin Panofskys Iconography, as well as through marxist and feminist theories. The analysis discusses how class and gender are produced in these paintings and I have reached the conclusion that they can be produced in different ways.

In a heterogeneous mobile ad hoc network (MANET), assorted devices with different computation and communication capabilities co-exist. In this thesis, we consider the case when the nodes of a MANET have various degrees of mobility and range, and the communication links are asymmetric. Many routing protocols for ad hoc networks routinely assume that all communication links are symmetric, if node A can hear node B and node B can also hear node A. Most current MAC layer protocols are unable to exploit the asymmetric links present in a network, thus leading to an inefficient overall bandwidth utilization, or, in the worst case, to lack of connectivity. To exploit the asymmetric links, the protocols must deal with the asymmetry of the path from a source node to a destination node which affects either the delivery of the original packets, or the paths taken by acknowledgments, or both. Furthermore, the problem of hidden nodes requires a more careful analysis in the case of asymmetric links. MAC layer and routing protocols for ad hoc networks with asymmetric links require a rigorous performance analysis. Analytical models are usually unable to provide even approximate solutions to questions such as end-to-end delay, packet loss ratio, throughput, etc. Traditional simulation techniques for large-scale wireless networks require vast amounts of storage and computing cycles rarely available on single computing systems. In our search for an effective solution to study the performance of wireless networks we investigate the time-parallel simulation. Time-parallel simulation has received significant attention in the past. The advantages, as well as, the theoretical and practical limitations of time-parallel simulation have been extensively researched for many applications when the complexity of the models involved severely limits the applicability of analytical studies and is unfeasible with traditional simulation techniques. Our goal is to study the behavior of large systems consisting of possibly thousands of nodes over extended periods of time and obtain results efficiently, and time-parallel simulation enables us to achieve this objective. We conclude that MAC layer and routing protocols capable of using asymmetric links are more complex than traditional ones, but can improve the connectivity, and provide better performance. We are confident that approximate results for various performance metrics of wireless networks obtained using time-parallel simulation are sufficiently accurate and able to provide the necessary insight into the inner workings of the protocols.

Ensuring trustworthiness through mobile nodes is a serious issue. Indeed, securing the routing protocols in Mobile Ad Hoc Network (MANET) is of paramount importance. A key exchange cryptography technique is one such protocol. Trust relationship between mobile nodes is essential. Without it, security will be further threatened. The absence of infrastructure and a dynamic topology changing reduce the performance of security and trust in mobile networks. Current proposed security solutions cannot cope with eavesdroppers and misbehaving mobile nodes. Practically, designing a key exchange cryptography system is very challenging. Some key exchanges have been proposed which cause decrease in power, memory and bandwidth and increase in computational processing for each mobile node in the network consequently leading to a high overhead. Some of the trust models have been investigated to calculate the level of trust based on recommendations or reputations. These might be the cause of internal malicious attacks. Our contribution is to provide trustworthy communications among the mobile nodes in the network in order to discourage untrustworthy mobile nodes from participating in the network to gain services. As a result, we have presented an Elliptic Curve Diffie-Hellman key exchange and trust framework mechanism for securing the communication between mobile nodes. Since our proposed model uses a small key and less calculation, it leads to a reduction in memory and bandwidth without compromising on security level. Another advantage of the trust framework model is to detect and eliminate any kind of distrust route that contain any malicious node or suspects its behavior.

No description available.

Wireless mobile ad-hoc networks consist of a collection of peer mobile nodes that form a network and are capable of communicating with each other without help from stationary infrastructure such as access points. The availability of low-cost, com-modity network interface cards (NICs) has made the IEEE 802.11 medium access control (MAC) protocol the de facto MAC protocol for wireless mobile ad-hoc net-works, even though it is not optimal. The IEEE 802.11 MAC protocol is designed to have stations share a single channel in a given network. However, many of the IEEE 802.11 physical (PHY) layer specifications define multiple channels and allow the simultaneous, non-interfering use of some of these channels. Therefore, multiple communications can occur at the same time, offering the opportunity to increase the effective network capacity. We present an innovative routing protocol that utilizes multiple channels to im-prove the performance of wireless ad-hoc networks. The basic idea of the protocol is to use multiple channels so that multiple useful transmissions can occur simultane-ously, thus increasing network capacity. The proposed scheme requires minor changes to existing proactive ad-hoc routing protocols and no modifications to the current IEEE 802.11 MAC protocol. To reduce inefficiencies due to periodic updates in the proactive routing protocols, the proposed scheme divides the network layer into control and data planes. Nodes send routing updates using the control channel and user packets using the data channel. To demonstrate the multi-channel routing scheme, we extend the Destination-Sequenced Distance-Vector (DSDV), Open Shortest Path First-Minimal Connected Dominating Set (OSPF-MCDS), and Optimized Link State Routing (OLSR) protocol to multiple channel (MC) versions, denoted as DSDV-MC, OSPF-MCDS-MC, and OLSR-MC, respectively. Simulation results for DSDV-MC, OSPF-MCDS-MC, and OLSR-MC are presented and experimental results for OLSR-MC are presented. Simulation results indicate that DSDV-MC and OSPF-MCDS-MC effectively exploit multiple channels to improve network capacity. Goodput, the throughput consider-ing only useful error-free packets, increases with an increased number of available channels as the number of nodes and network load increase in both single-hop and multiple-hop networks. Experimental results with OLSR-MC also support that the proposed scheme increases network capacity without modification to the MAC proto-col in a real implementation. Although simulation and experimental results show that proposed scheme im-proves network capacity by exploiting multiple channels, problems exist with channel distribution. We introduce a new metric, the Channel Distribution Index (CDI) to in-vestigate these issues. The CDI indicates the fairness of the channel distribution. We identify the channel convergence problem, where a particular channel is over-utilized, and propose a channel reallocation scheme to mitigate the impact of the channel convergence problem using the CDI. / Ph. D.

Publish/subscribe (P/S) is a communication paradigm of growing popularity for information dissemination in large-scale distributed systems. The weak coupling between information producers and consumers in P/S systems is attractive for loosely coupled and dynamic network infrastructures such as ad hoc networks. However, achieving end-to-end timeliness and reliability properties when P/S events are causally dependent is an open problem in ad hoc networks. In this thesis, we present, evaluate benefits of, and compare with past work, an architecture design that can effectively support timely and reliable delivery of events and causally related events in ad hoc environments, and especially in mobile ad hoc networks (MANETs). With observations from both realistic application model and simulation experiments, we reveal causal dependencies among events and their significance in a typical use notional system. We also examine and propose engineering methodologies to further tailor an event-based system to facilitate its self-reorganizing capability and self-reconfiguration. Our design features a two-layer structure, including novel distributed algorithms and mechanisms for P/S tree construction and maintenance. The trace-based experimental simulation studies illustrate our design's effectiveness in both cases with and without causal dependencies. / Master of Science

行動隨意式網路(MANET)是一種具有高度動態拓撲結構的網路。每一個行動隨意式網路由一組移動節點(Node)組成，彼此之間互相支援轉送封包可以不依靠基地台建構成Intranet。此種網路中，因節點移動之緣故，連線不穩定、頻寬較窄，錯誤率亦較高。傳統的TCP傳輸協定在行動隨意式網路上的效能不免遭受重創。 傳統的TCP在封包遺失時，只能從傳送端進行重傳，而行動隨意式網路傳輸品質極不穩定，常常重送多次才可到達目的地，導致要耗費極長的時間才能將封包送達目的地，然而，在行動隨意式網路中，大量傳輸資料的需求並不大，反而是封包的快速送達更為重要，因此加速封包的送達成為比增大傳送量更為重要的目標。 為了使封包較快送達目的地端，我們提出了Hop-by-Hop TCP的方法，使每個節點使用當地重傳以保證封包成功的傳到下一個節點，遺失的封包不必重新由傳送端重傳，能更快反應封包遺失，並且提昇傳輸可靠度，使封包在高遺失率的情形之下能順利且較為快速的送達目的地端。 我們利用NS-2網路模擬器進行實驗，驗證我們的機制，實驗在不同的拓樸及負載等參數下進行，觀察傳輸成功率及封包傳輸時間，以及公平性。實驗結果指出，本方法在網路環境不穩定時吞吐量能有25.7%以上的提昇，而延遲時間也能有25%的提昇，亦有相當好的公平性。 / A Mobile Ad hoc Network (MANET) MANET is composed of a group of mobile computing devices (nodes) that are equipped with Wireless LAN (WLAN) capability. Nodes can transmit packets to each other to construct Intranet without any base station. In an MANET environment, the communication links are unstable due to various reasons. Error rate is higher and bandwidth is smaller than fixed networks. Running regular TCP protocol on MANET will suffer from serious performance degradation in MANET. To handle packet lost, regular TCP can only retransmit lost packets from the source. However, when error rate is high, several retransmissions may be needed to transmit a packet to its destination successfully. As a result, the effective bandwidth is much lower and the average time to transmit a packet will be much longer. Considering that most applications on MANET prefer shorter transmission time to higher bandwidth, this thesis proposes Hop-by-Hop TCP protocol aiming to accelerate the transmission of packets. Hop-by-Hop TCP makes every intermediate node in the transmission path running a local TCP to guarantee the transmission of each packet on each link. The retransmission of a lost packet is right at the transmitting end of the link where the packet is lost. It doesn't need to retransmit a lost packet from its source node. It takes less time in average to transmit a packet to its destination in a high error rate environment. We evaluate the performance of our approach by simulation using NS-2 simulator. Our experiments show that our proposed protocol outperforms TCP Reno by 25.7% in throughput and 25% reduction in average transmission time. The fairness requirement is also achieved while our proposed protocol coexists with other major TCP variants.

藉由許多配備無線通訊能力的嵌入式系統裝置，如筆記型電腦、行動電話、PDA、車用導航系統及車用電腦等，不同的裝置透過無線通訊的能力，將彼此連接，構成行動隨意網路 (Mobile Ad Hoc Network) 的環境。這些網路上的節點可能任意且快速移動，隨時改變既有網路拓樸，造成原先已經建立好的路由中斷。採用被動式路由協定 (Reactive Routing Protocol) 的路由重建，往往增加了資料傳送的延遲及重建路由時所需要大量路由發現 (Route Discovery) 的封包，造成廣播風暴 (Broadcast Storm)，嚴重影響整個網路的效能。 在論文中，我們提出一個利用節點的移動方向做為選擇適當中繼節點 (Relay Node) 的策略，稱之為Directive Location-Aided Routing，簡稱DLAR。DLAR將節點的移動方向因素加入於既有的LAR中做為選擇中繼節點的考量。中繼節點的決定，需要符合與來源節點相同的移動方向，目的是維持較長的連線時間，且讓路由中斷的位置靠近目的節點，並使用AODV的Local Repair的機制做為路由搜尋的協定，加速路由的恢復。 實驗模擬結果顯示，DLAR與AODV、DSR及LAR比較，在減少找尋路由路徑時所需的路由請求封包、降低點對點 (End -To-End) 的延遲及資料成功送達率，都有較佳的表現。在網路中節點數較多時，DLAR在封包送達率能有6%– 55%的改善，降低搜尋及維持路由時需要的控制封包量達40%以上，降低廣播風暴發生的機率， DLAR也同時在End-to-End Delay的表現較之於其他路由機制，有20%以上的改善。 / In MANET the nodes may move fast and unpredictable, this may cause the original set up route well broken. Adopt those Reactive Routing Protocols may not only cause seriously data delivery delay but also produce a large number of control packages (RREQ) thus reducing network capacity. This is known as Broadcast Storm Problem. In this thesis, we proposed a routing protocol, Directive Location-Aided Routing (DLAR), that helps to choose appropriate relay nodes (intermediate nodes) in MANET. DLAR considers the node movement direction factor in deciding a stable route. Relay node is considered to be the same movement direction as source node. The goal is to maintain longer path lifetime, and make the broken very close to the destination node. DLAR adopts AODV to discovery route and accelerate the route recovery using Local Repair mechanism. Simulations show that as the network loading is high, DLAR can increase the packet delivery ratio by 6% ~ 55 % and increase the bandwidth utility by 40%, reduce the largely broadcast storm probability, and reduce end-to-end delay by 20%.

Ad hoc mobile wireless networks are self-configuring infrastructureless networks of mobile devices connected via wireless links. Each device can send and receive data, but it should also forward traffic unrelated to its own use. All need to maintain their autonomy, and effectively preserve their resources (e.g. battery power). Moreover, they can leave the network at any time. Their intrinsic dynamicity and fault tolerance makes them suitable for applications, such as emergency response and disaster relief, when infrastructure is nonexistent or damaged due to natural disasters, such as earthquakes and flooding, as well as more mundane, day-to-day, uses where their flexibility would be advantageous. Routing is the fundamental research issue for such networks and refers to finding and maintaining routes between nodes. Moreover, it involves selecting the best route where many may be available. However, due to the freedom of movement of nodes, new routes need to be constantly recalculated. Most routing protocols use pure broadcasting to discover new routes, which takes up a substantial amount of bandwidth. Intelligent rebroadcasting reduces these overheads by calculating the usefulness of a rebroadcast, and the likelihood of message collisions. Unfortunately, this introduces latency and parts of the network may become unreachable. This dissertation presents a routing protocol that uses a new parallel and distributed guided broadcasting technique to reduce redundant broadcasting and to accelerate the path discovery process, while maintaining a high reachability ratio as well as keeping node energy consumption low. This broadcasting scheme is implemented in a Mobile Ad Hoc Network (MANET) and a Wireless Mesh Network (WMN). To reduce overheads further, a Zone based Routing with Parallel Collision Guided Broadcasting Protocol (ZCG) in MANET is introduced. This uses a one hop clustering algorithm that splits the network into zones led by reliable leaders that are mostly static and have plentiful battery resources. For WMN, a Social-aware Routing Protocol (SCG) is designed that draws upon social network theory to associate longstanding social ties between nodes, using their communication patterns to divide the network into conceptual social groups, which allows cluster members to protect each other from redundant broadcasts by using intelligent rebroadcasting. The performance characteristics of the new protocols are established through simulations that measure their behaviour and by comparing them to other well-known routing protocols, namely the: AODV, DSR, TORA and the OLSR, as appropriate, it emerges that two new protocols, the ZCG and SCG, perform better in certain conditions, with the latter doing consistently well under most circumstances.