With the development of computer technology and Internet, e-Learning has become more and more important to support student¡¦s learning. Novice students usually lack adequate assisting tools especially in programming learning. Therefore, we propose the problem-based Python programming learning system with extendable item-bank. The system can generate program debugging exercise by using mutation testing technology. Additionally, for enhancing student¡¦s problem-exploration and reasoning capacity, the system provide another practice - Programming Exercise Creating Practice. In this kind of practice, every student can create his own programming exercise using question template and answer code template. This practice not only can enhance student¡¦s capacity but also can rich enrich the system¡¦s item-bank by using this strategy. Different from other programming learning systems, our system provide a more complete trainings on programming capacities, and building with Web2.0 concept. So, student who learns programming on this system will not only do exercise, but he also can help other students. So, student can get more kind of learning chance in this way. Additionally, we also hope that teacher¡¦s loading will be decreased and quality of course will be increased by using this system.

Let G be a simple connected graph on 2n vertices with a perfect matching. For 1 ≤ k ≤ n - 1, G is said to be k-extendable if for every matching M of size k in G there is a perfect matching in G containing all the edges of M. A k-extendable graph G is said to be k-critical (k-minimal) if G+uv (G-uv) is not k-extendable for every non-adjacent (adjacent) pair of vertices u and v of G. The problem that arises is that of characterizing k-extendable, k-critical and k-minimal graphs.In Chapter 2, we establish that δ(G) ≥ 1/2(n + k) is a sufficient condition for a bipartite graph G on 2n vertices to be k-extendable. For a graph G on 2n vertices with δ(G) ≥ n + k 1, n - k even and n/2 ≤ k ≤ n - 2, we prove that a necessary and sufficient condition for G to be k-extendable is that its independence number is at most n - k. We also establish that a k-extendable graph G of order 2n has k + 1 ≤ δ(G) n or δ(G) ≥ 2k + 1, 1 ≤ k ≤ n - 1. Further, we establish the existence of a k-extendable graph G on 2n vertices with δ(G) = j for each integer j Є [k + 1, n] u [2k + 1, 2n 1]. For k = n - 1 and n - 2, we completely characterize k-extendable graphs on 2n vertices. We conclude Chapter 2 with a variation of the concept of extendability to odd order graphs.In Chapter 3, we establish a number of properties of k-critical graphs. These results include sufficient conditions for k-extendable graphs to be k-critical. More specifically, we prove that for a k-extendable graph G ≠ K2n on 2n vertices, 2 ≤ k ≤ n - 1, if for every pair of non-adjacent vertices u and v of G there exists a dependent set S ( a subset S of V (G) is dependent if the induced subgraph G[S] has at least one edge) of G-u-v such that o(G-(S u {u,v})) = S, then G is k-critical. Moreover, for k = 2 this sufficient condition is also a necessary condition for non-bipartite graphs. We also establish a ++ / necessary condition, in terms of the minimum degree, for k-critical graphs.We conclude Chapter 3 by completely characterizing k-critical graphs on 2n vertices for k = 1, n - 1 and n - 2.Chapter 4 contains results on k-minimal graphs. These results include necessary and sufficient conditions for k-extendable graphs to be k-minimal. More specifically, we prove that for a k-extendable graph G on 2n vertices, 1 ≤ k ≤ n - 1, the following are equivalent:G is minimalfor every edge e = uv of G there exists a matching M of size k in G-e such that V(M) n {u,v} = ø and for every perfect matching F in G containing M, e Є F.for every edge e = uv of G there exists a vertex set S of G-u-v such that: M(S) ≥ k; o(G-e-S) = S - 2k + 2; and u and v belong to different odd components of G-e-S, where M(S) denotes a maximum matching in G[S].We also establish a necessary condition, in terms of minimum degree, for k-minimal and k-minimal bipartite graphs. In fact, we prove that a k-minimal graph G ≠ K2n on 2n vertices, 1 ≤ k ≤ n - 1, has minimum degree at most n + k - 1. For a k-minimal bipartite graph G ≠ Kn,n , 1 ≤ k ≤ n - 3, we show that δ(G) < ½(n + k).Chapter 1 provides the notation, terminology, general concepts and the problems concerning extendability graphs and (k,t)-critical graphs.

Today, the average computer user has undoubtedly encountered the PDF format while handling electronic documents. Due to its wide-spread popularity and feature richness, PDF documents are commonly utilized by attackers in order to infect systems with malware. This thesis will present The Extendable Guideline for Analysing Malicious PDF Documents. This work will establish the foundation of the guideline and populate it with a part of the analysis process. The guideline relies on earlier published material in the topic. It is a practical guideline that is followed by the use of a flowchart and can be utilized by an analyst in order to determine if a PDF document is malicious or not. It provides technical background information, suitable analysis techniques, and tools. The guideline structure was developed by using sequential thinking in combination with the divide and conquer paradigm. The thesis will also elucidate commonly applied techniques that are used by malicious PDF authors in order to infect systems, evade detection, and distribute their malicious documents. A commonly utilized function in PDF documents are the JavaScript feature. There are a wide range of other features that are targeted by malicious PDF authors, but they are more rarely encountered. PDF documents are often distributed by attackers by sending them as an attachment in an email, or storing the document on a web server.

A Hamilton cycle in a graph is a cycle that passes through every vertex of the graph. A graph is called Hamiltonian if it contains such a cycle. In this thesis we investigate two classes of graphs, defined by local criteria. Graphs in these classes, with a simple set of exceptions K, were proven to be Hamiltonian by Asratian, Broersma, van den Heuvel, and Veldman in 1996 and by Asratian in 2006, respectively. We prove here that in addition to being Hamiltonian, graphs in these classes have stronger cyclic properties. In particular, we prove that if a graph G belongs to one of these classes, then for each vertex x in G there is a sequence of cycles such that each cycle contains the vertex x, and the shortest cycle in the sequence has length at most 5; the longest cycle in the sequence is a Hamilton cycle (unless G belongs to the set of exceptions K, in which case the longest cycle in the sequence contains all but one vertex of G); each cycle in the sequence except the first contains all vertices of the previous cycle, and at most two other vertices. Furthermore, for each edge e in G that does not lie on a triangle, there is a sequence of cycles with the same three properties, such that each cycle in the sequence contains the edge e.

The following thesis project has been done in direct collaboration with Autokaross i Floby AB Rescue Vehicle Department, in Sweden.  The report contains the design development of a protective cover against weather conditions for the extendable ladder in a fire vehicle.   The aim of the report has been to develop a functional and low cost solution cover for the FEL on a fire truck, which is allocated on the roof, with the express intention of providing adequate access and protection against weather conditions in Nordic countries, so as to prevent premature deterioration of the FEL unit. The company has set the technical and conceptual boundaries, with the help of the two previous concepts currently used, the BMC and the ACP.   The initial requirements laid out by the company were expressed through a number of specific demands which can be categorized in two main points:   Cost: Designing a solution keeping in mind cost limits, assembly cost and time, and space optimization. This was done by taking into account the two existing solutions, particularly the BMC, which represents the lowest, cost wise and function wise. Therefore it was used as the basis on which to apply improvements, rather than trying to lower the high cost on the overqualified function of the ACP.   Function: Providing the adequate protection and access to the FEL. In this case, the problem was solved by establishing the correct degree of protection relevant to the Nordic weather conditions and FEL needs, and regarding the access, this was assured by fully automating the opening/closing process with the existing extraction operating system of the FEL.     The result of this report is a concept solution which meets the company’s demands, obtained by creative detailing, together with an analysis regarding possible considerations that could improve the creative detailing result in this report in the form of future work.     The report documents the process that has taken place in exploration, concept generation, concept evaluation, concept selection, and detailed CAD development. Each section shows the requirements and adjustments taken to fulfil the company’s needs.