Because there has been a rapid development in wireless networks, it is important to provide quality-of-service (QoS) guarantees as they are expected to support multimedia applications. In this paper we propose a new bandwidth reservation scheme based on the characteristic of the cell equipped with sector antenna and 2-tier cell structure. According to this information, the proposed scheme can predict the next location of each connection and precisely reserve bandwidth in appropriate neighboring cells, not all of its neighboring cells. In addition, the proposed scheme incorporates bandwidth borrowing mechanism into call admission control strategy. The combination of bandwidth reservation and bandwidth borrowing provides network users with QoS in terms of guaranteed bandwidth, call blocking and call dropping probabilities.

This study aimed at investigating university preparatory school students&rsquo / and teachers&rsquo / perceptions of computer-assisted language learning (CALL) environment. The sample consisted of 308 students and 50 teachers from Zonguldak Karaelmas University Preparatory School. Data was gathered from the participants via two Effective CALL Questionnaires (ECALLQ) developed by the researcher. Both inferential and descriptive statistics were used to analyze the data. Principal component analysis was used to find the dimensions of the student questionnaire. Repeated measures ANOVA and paired-samples t-test were employed to define the priorities of the students within the dimensions of each subscale. MANOVA was used to investigate whether there were significant differences among students&rsquo / CALL environment perceptions with respect to certain background variables.Descriptive statistics were used to analyze students&rsquo / and teachers&rsquo / perceptions of computer&rsquo / s role and teacher&rsquo / s role in CALL environment and to analyze all participants&rsquo / responses to the open-ended questions.The study indicated that students perceive the computer&rsquo / s role with respect to (1)language skills, (2) overall effect of computer and (3) motivation / teacher&rsquo / s role with respect to (1) teacher assistance, (2) teacher guidance and (3) teacher presence / students&rsquo / expectations from the teacher with respect to (1) laboratory activities guided by the teacher and (2) overall guidance. According to the students&rsquo / perceptions, language skills,teacher assistance and lab activities guided by the teacher were found to be the most effective dimensions.Descriptive statistics showed that both students and teachers are undecided about the effectiveness of CALL, and they believe that teachers are effective in CALL environment.

In the near future, the integration of GSM and GPRS services will bring the wireless personal communication networks into a new era. With the extreme growth in the number of users for contending limited resources, an efficient channel allocation scheme for GSM/GPRS users become very important. Currently, existing channel allocation schemes do not consider the various characteristics of traffic classes. Consequently, users can not obtain their optimal channel resources in delivering different types of traffic. In this thesis, a preemptive channel allocation mechanism is introduced for GSM/GPRS cellular networks. Based on the call requests, for different types of services, we classify the traffic into GSM, real-time GPRS and non-real-time GPRS. Two channel thresholds are defined. TGSM/GPRS is used to separate the channels between GSM and GPRS users, while TGPRS_rt is used to separate the channels between real-time and non-real-time GPRS users. Since the two thresholds can be dynamically adjusted based on the number of call requests, the channel utilization is increased and less resources are wasted. Note that in our proposed scheme, high-priority users¡]i.e., GSM handoff calls¡^can preempt the channels being used by low-priority users¡]i.e., non-real-time GPRS calls¡^. Hence, the call blocking probability of high-priority calls can be significantly reduced and their quality of services can be guaranteed as well. We build a 3-D Markov Chain mathematical model to analyze our proposed channel allocation schemes. The parameters of our interests include the call blocking probability, the average number of active calls, the average call completion rate and the overall channel utilization. To verify our mathematical results, we employ OPNET simulator to simulate the proposed schemes. Through the mathematical and simulation results, we have observed that with the preemptive channel allocation, the high-priority calls¡]i.e., GSM and real-time GPRS¡^can achieve relatively low blocking probability while slightly increasing the blocking probability of non-real-time GPRS calls. Besides, the overall channel utilization is greatly improved due to the appropriate channel allocation.

The author used Put-Call-Futures Parity, Arbitrage-Free, Ex-ante Tests and Ex-post Tests to examine the arbitrage opportunity and market efficiency of the TAIEX index futures (TX) and the TAIEX index options (TXO) in this paper, during the period of December 24th, 2001 to December 31st, 2002. The author first, used daily closing prices to test for the existence of possible arbitrage opportunities. Second, she used ex-ante tests and arbitrage strategy to examine the arbitrage opportunity whether it exists or not with a time lag. Furthermore, The author classified the samples which exist ex-post arbitrage profit into five sub-samples according to call options positions belonging to near-the-money and far-from-the-money, futures positions belonging to positive basis and negative basis, markets belonging to bull markets and bear markets, and different margin requirement. She used ex-post and ex-ante tests to compare the results of over-all markets samples with the sub-samples, then, she also examined the results of included transaction cost or not. The major findings are as follows: 1. Whether taking into transaction cost or not, the TAIEX index futures and the TAIEX index options markets have arbitrage opportunity¡Aand so the markets unefficient. 2. The results of ex-ante tests and the average of arbitrage profit are positive for time to increase. 3. The long arbitrage strategy generates a higher arbitrage profit than the short arbitrage strategy. 4. The investors could proceed arbitrage profit during markets belonging to positive basis and bear market and low margin requirement.

Most of the derivative pricing models are developed in the jump diffusion models, and many literatures assume those jumps are diversifiable. However, we find many risk cannot be avoided through diversification. In this paper, we extend the Jarrow and Yildirim model to consider the existence of systematic jump risk in nominal interest rate, real interest rate and inflation rate to derive the no-arbitrage condition by using Esscher transformation. In addition, this study also derives the value of TIPS and TIPS European call option. Furthermore, we use the econometric theory to decompose TIPS market price volatility into a continuous component and a jump component. We find the jump component contribute most of the TIPS market price volatility. In addition, we also use the TIPS yield index to obtain the systematic jump component and systematic continuous component to find the systematic jump beta and the systematic continuous beta. The results show that the TIPS with shorter time to maturity are more vulnerable to systematic jump risk. In contrast, the individual TIPS with shorter time to maturity is more vulnerable to systematic jump. Finally, the sensitive analysis is conducted to detect the impacts of jumps risk on the value of TIPS European call option.

Telecommunication systems have evolved significantly and the recent convergence of telephony allows users to communicate through landlines, mobile phones and Voice over IP (VoIP) phones. Unfortunately this convergence has resulted in easy manipulation of caller identity, resulting in both VoIP spam and Caller ID spoofing. In this dissertation, we introduce the notion of effective identity which is a combination of mechanisms to (1) establish identity of the caller that is harder to manipulate, and (2) provide additional information about the caller. We first use effective identities to address the VoIP spam problem by proposing CallRank, a novel mechanism built around call duration and social network linkages to differentiate between a legitimate user and a spammer. To ensure that this mechanism is privacy preserving, we create a token framework that allows a user to prove the existence of a social network path between him and the user he is trying to initiate contact with, without actually revealing the path. We then look at the broader issue of determining identity across the entire telecommunication landscape to address Caller ID spoofing. Towards this, we develop PinDr0p, a technique to determine the provenance of a call - the source and the path taken by a call. In the absence of any verifiable metadata, provenance offers a means of uniquely identifying a call source. Finally, we use anomalies in timbre to develop London Calling, a mechanism to identify geography of a caller. Together, the contributions made in this dissertation create effective identities that can help address the new threats in a converged telecommunication infrastructure.

<p>Software vulnerabilities in programs and malware deployments have been increasing almost every year since we started measuring them. Information about how to program securely, how malware shall be avoided and technological countermeasures for this are more available than ever. Still, the trend seems to favor the attacker. This thesis tries to visualize the effects of a selection of technological countermeasures that have been proposed by researchers. These countermeasures: non-executable memory, address randomization, system call interception and file integrity monitoring are described along with the attacks they are designed to defend against. The coverage of each countermeasure is then visualized with the help of attack trees. Attack trees are normally used for describing how systems can be attacked but here they instead serve the purpose of showing where in an attack a countermeasure takes effect. Using attack trees for this highlights a couple of important aspects of a security mechanism, such as how early in an attack it is effective and which variants of an attack it potentially defends against. This is done by the use of what we call defensive codes that describe how a defense mechanism counters a sub-goal in an attack. Unfortunately the whole process is not well formalized and depends on many uncertain factors.</p>

<p>In this thesis an approach to visualize internal behaviour of object oriented software is developed.</p><p>The runtime information, which can be described as objects calling other objects, is displayed as a graph consisting of nodes and edges. The aim is to design an application in Java, which takes the runtime information in form of an object call graph and visualizes it as a tree and as a force directed view.</p><p>Therefore, first a data model has to be designed, holding an object call sequence. Furthermore, a discussion about graph definition languages and according tools is made. After this different graph layout algorithms are examined as well as graph displaying tools. Finally, the implementation of this visualization program deals with the combination of these three components graph data extraction, graph layout calculation and graph visualization.</p>

<p>Outsourcing och specifikt callcenter outsourcing diskuteras bland företag. Tyngden i diskussionen ligger på kvalitén, som är en aktuell aspekt av fenomenet callcenter outsourcing. Frågan berör flera parter; de företag som outsourcar, callcenter och konsumenter. Callcenters är organisationer som är specialiserade inom kundkontakt och har i uppgift att kommunicera med företags konsumenter, genom att svara på frågor eller bidra med övrig information och hjälp som konsumenten är i behov av.</p><p>Teorier som ligger till grund för vår uppsats, rör callcenter outsourcing, kvalitet och kvalitetssystem. Vidare har vi diskuterat var forskningen står idag och utifrån det identifierat vårt valda forskningsområde, där vi ämnar besvara frågan gällande vilka olika kvalitetskrav som kunden ställer och hur dessa säkerställs hos den outsourcade callcenterfunktionen, det vill säga leverantören av tjänsten. Kvalitetsaspekten är av stor vikt, därför att dålig service direkt reflekteras på det företag som outsourcar tjänsten, trots att det inte själva utför den. Bristande kvalitet kostar stora summor för verksamheter, närmare bestämt 10 – 30 procent av dess omsättning och därav är det av vikt att företag som outsourcar tjänster och leverantörer som levererar tjänsterna, är införstådda i vikten av kvalitetsaspekten.</p><p>Det slutsatser vi dragit i uppsatsen, är att kunderna ställer olika krav på leverantörerna beroende på den typ av tjänst som ska levereras. Kraven kan handla om bemötande, sekretess, tillgänglighet och att hålla en specifik standard. Dessutom har vi i uppsatsen kommit fram till att leverantörerna använder sig av olika kvalitetssystem för att säkra kvalitén på tjänsterna som outsourcas, allt från kvalitetssystemet ISO9000 och COPC till egenutformade kvalitetssystem och avtal.</p> / <p>Outsourcing, especially call centre outsourcing, is discussed in many companies. One topic in the discussion is the quality of the service provided. The quality is important for all involved parties, companies who outsource their call centre, the call centre and especially for the consumers. Call centres are companies specialized in customer contact, undertaking the communication between the consumer and the company, through answering questions, providing information or support.</p><p>The theories that initiates this essay is based on call centre outsourcing, quality and quality systems. Through a discussion of previous research, we specify our main area of the study. We intend to answer the question of how the quality requirements set by the company is guaranteed by the call centre. Quality is an important topic since the company outsourcing is directly affected by bad service quality. Poor quality is a high cost driver for companies, and research has shown that deficient quality can reduce the company’s turnover by 10-30 percent.</p><p>The conclusion in this essay is that companies set different demands on the call centre, depending on what type of service they agree on. The demands could be about behaviour, secrecy, availability or maintaining a specific level of standard and quality. To secure the level of quality, call centres use different quality systems, such as ISO9000, COPC, systems developed by the call centre it self or service level agreements.</p>

Call centers are an important function of most companies’ day to day business activities. They are often the link between a company and its customers and hugely impact the customer’s perspective or point of view (POV) of a company. A call center in the most general sense is a place, representing a business, which receives inbound calls from customers and/or makes outbound calls to customers, the latter being most commonly referred to as telemarketing. There was a time when a typical call center strictly consisted of agents who handled inbound/outbound calls; these agents are considered specialized agents. Generally speaking, a specialized agent is one trained, in-depth, in a particular area of knowledge.Most businesses have transgressed from your typical call center into contact centers. Contact centers operate essentially the same as a call center but interact with the customer in a variety of ways including, but not limited to: Phone, Mail, Fax, Email, and Internet (via online chat and instant messaging applications). The dynamics of these kinds of call centers has caused an increase in the need for agents to become more diverse in their talents and abilities to handle different types of calls. This has lead to specialized agents becoming general or “cross-trained” agents in which they are trained, broadly, over several areas of knowledge.The purpose of this thesis is to compare specialized agents to cross-trained agents and through the use of simulation, determine which of the two are more efficient and reliable in their ability to service the customer. This thesis has three major components: Simulation, Reliability Analysis, and Comparison. The results indicate that a cross-trained model is more reliable and efficient than a specialized model. Performance metrics common to call center literature, simulation, and Lean reliability systems were used to determine the effectiveness and reliability of the two models.