At beginning of this paper, it will introduce the SIP protocol major used on the VoIP service at present time. Introduce the development and the application of SIP. And then explain the operation of the SIP protocol by an example. Explain how a SIP client establish the communication with another one by the SIP proxy. After understanding the operation of the SIP, explain why the SIP client behind NAT will meet the fail and introduce the solutions that have developed to conquer the fail. Briefly describe each of these solutions and compare all of them. Next is to describe how the solution of statteful SIP proxy used to avoid the fail of NAT changes the behavior between the SIP clients from end-to-end to master-to-slave. The change of behavior between the SIP clients may affect the quality of the communication in some conditions. To improve this, this paper brings out an idea and implements it. Finally, test the quality of the communication, catch the packet carrying the SIP messages and packet of RTP, and watch the content of SIP messages and the routing of the RTP packet.

The Irish singing session has provided a safe community where singers of all abilities are welcome to share with and learn from one another. Through British occupation and into independence, the Irish session has transformed tremendously from its original form. Still, the session carries on the Irish tradition of music learning and enculturation through oral transmission. Singing sessions provide a unique opportunity for the many songs of Irish history to be sung and learned; passed down from generation to generation! Singers learn new songs through listening to and watching other singers, imitating material, experimenting with new ideas, and discussing musical performances with others. Session leaders may attempt to create an encouraging and accepting environment where singers feel secure, resulting in the unbridled sharing of singers’ deep connections with a song. Such methods, including personal choice and a safe environment, have been observed through field research and have shown to positively affect singers and communities related to singing sessions in County Clare, Ireland. In this study, I pose that the methods used in singing sessions may also be beneficial when adapted for use in the music classroom. / Music Education

The rapidly increasing expansion and popularity of the Internet makes more and more users accept web service type. The web server with single server architecture is no longer satisfying a large number of user requests. The web cluster architecture becomes another batter solution. In our previous work, our laboratory has implemented a prototype of layer7 web switch, which provides content-aware land balancing. We also designed and implemented a management system to provide a easy way for system configuration. With the increasing of web technologies, most of web sites supply ¡§session-aware¡¨ service type. The session is that clients and servers that wish to exchange state information to place HTTP requests and responses within a lager context. In this paper, we propose a session-aware management in the web cluster. Base on our management system, we design a fault tolerance and QoS policy with session to improve performance and reliability of our web cluster system.

Abstract We propose to research the interaction between users and web servers in Internet , and we call that ¡§Session - Based model¡§ . Then we add some policies to the session-based model , we define that is ¡§Session - Based Management¡§ . For the explosive growth of Internet service¡]eg.,e-commerce¡K¡^, we consider about what users want and tracing users¡¦ behaviors , those are what we want to research and analysis . We using ¡§cookie¡§ , what is the technique to use on the Client-Server model of Internet . This make server directly and easily know some information about users . So server supply quality of service to user what they have identified . Then we trace technologies of cookie which are used in some popular web sites¡]eg., eBay , ubid , kimo , openfind¡^, and analyze the impact of users about those technologies . For example , we classify the Internet service to ¡V shopping cart¡Bsearch engine¡K Finally , we construct our e-commerce web site to parsing every packets through our site , getting the information what we want from those packets , and then we define our some policies into our Session-Based model . The infrastructure of our implementation environment is in Server Cluster Architecture , which is the most popular one this time . More and more ISPs¡]Internet Service Provider¡^or ICPs¡]Internet Content Provider¡^construct their web sites in this kind of structure . In our cluster system , our distributor will analyze all kinds of packets from all heterogeneous servers . Using our technique will make distributor to learn how to know the user information and identify the users , so distributor will know how to supply users¡¦ session-based priority¡Bdifferentiated service and so on . We actually implement our mechanisms in our server cluster system .

As WWW service grow up rapidly and becomes the most popular information system on the internet, web site owner invest heavily to improve the performance of web server. And, because of the 'Server Farm' architecture comes real, web server performance breaks the limit of single server, which directly cause server performance improvement. All these factors raise the cost of website performance measurement program to catch up server performance. Besides, because of dynamic webpage and database linkage are applied widely in production environment. HTTP requests (for example, sessions) with state and identifications increase rapidly. Traditional Web Benchmarking methods are out of date and not supporting these new transaction models. Also, traditional benchmarking methodologies only provide the max/average values for overview, which can not properly describe the performance of the websites with massive dynamic webpages. All these problems shows the traditional benchmarking methodologies are not sufficient for today's technologies. In this paper, we have designed and implemented a configurable and cost-effective website performance measurement program against these problems. We introduced the concept of 'workload', and pre-design detailed HTTP request table, where time, contains, and HTTP commands to use can be assigned. Also we use configurable and replaceable design of open modules and divide the major modules into workload generator, load generator and report generator. These modules can be even separated into three independent programs, which makes this benchmark program become more flexible and adaptive to fit new technologies without adjusting the kernel. We also introduced the concept of 'Virtual User' to describe a real user behavior. We could keep the HTTP state and identification by automatic reply via cookie and assigning user identification in the same process. To increase the efficiency, each load generator can do self-diagnostics and quantify the measurements, and properly reassign the workloads by the value returned by the system. These makes every load generator do everything it could, and not been halted by the low-speed machine. And we can also prevent the mis-measurement by overloading. From the result of the experience, our design can describe the web server performance and load changes by time. We can also compare it to request category and URL, to show the root of causes and time basis to administrator. Overall, our web benchmarking methodology shows the strength to traditional web benchmarking methods.

The Session Initiation Protocol (SIP) was designed for wire line networks. It was developed to initiate, modify and terminate sessions between two hosts on a network. When the Internet expanded to include wireless hosts, SIP did not scale well for these wireless hosts because of the nature of the wireless channel. Also, there were issues with mobility and real time communication. This thesis proposes improvements to some of the extensions to SIP, for better performance over wireless channels. We investigate the call setup time for various transport mechanisms viz. TCP and UDP, and study the performance of a dynamic Session Timers compared to the current standard of a periodic refresh mechanism, where the frequency of UPDATEs vary with the condition of the wireless channel. We also propose a handoff algorithm that reduces the handover time with decreased packet losses.

Class of 2009 Abstract / OBJECTIVES: To evaluate Club Medbox, a pharmacist-run intervention in which a pharmacist addresses barriers to treatment that arise in patients with HIV via a weekly educational group session. METHODS: A retrospective chart review and patient interview were utilized to evaluate Club Medbox member characteristics and changes in clinical HIV markers over the course of membership; and survey instruments were used to assess patient-perceived impacts of Club Medbox on overcoming barriers to antiretroviral therapy adherence, general health, social support, and disease- state comprehension. RESULTS: A total of 28 patients met inclusion criteria and were included in this study. HIV-ASES scores were significantly increased (p <0.001). SF-12 scores showed significant improvement for the physical health domain (p <0.001) with minimal changes to the mental health domain (p=0.949). CD 4 counts, CD 4%, and undetectable viral load values were all observed with an upward trend from baseline until after intervention with Club Medbox. Social and educational participant influence were shown to improve based on interview responses (p <0.001). CONCLUSIONS: This investigation showed significant improvement in the confidence of participants to adhere to treatment plans when barriers are present, self-perceived physical health, disease state management, patient-perception of feelings of social support, and patient-understanding of HIV as a disease state from baseline until after Club Medbox affiliation. This study did not show an influence of Club Medbox participation on self-perceived mental health. Club Medbox should be considered an effective intervention in the improvement of medication therapy adherence and disease state management in HIV positive patients.

A concurrent system is a computer system with components that run in parallel and interact with each other. Such systems are ubiquitous and are notably responsible for supporting the infrastructure for transport, commerce and entertainment. They are very difficult to design and implement correctly: many different modeling languages and verification techniques have been devised to reason about them and verifying their correctness. However, existing languages and techniques can only express a limited range of systems and properties. In this dissertation, we address some of the shortcomings of established models and theories in four ways: by introducing a general modal logic, extending a modelling language with types and a more general operation, providing an automated tool support, and adapting an established behavioural type theory to specify and verify systems with unreliable communication. A modal logic for transition systems is a way of specifying properties of concurrent system abstractly. We have developed a modal logic for nominal transition systems. Such systems are common and include the pi-calculus and psi-calculi. The logic is adequate for many process calculi with regard to their behavioural equivalence even for those that no logic has been considered, for example, CCS, the pi-calculus, psi-calculi, the spi-calculus, and the fusion calculus. The psi-calculi framework is a parametric process calculi framework that subsumes many existing process calculi. We extend psi-calculi with a type system, called sorts, and a more general notion of pattern matching in an input process. This gives additional expressive power allowing us to capture directly even more process calculi than was previously possible. We have reestablished the main results of psi-calculi to show that the extensions are consistent. We have developed a tool that is based on the psi-calculi, called the psi-calculi workbench. It provides automation for executing the psi-calculi processes and generating a witness for a behavioural equivalence between processes. The tool can be used both as a library and as an interactive application. Lastly, we developed a process calculus for unreliable broadcast systems and equipped it with a binary session type system. The process calculus captures the operations of scatter and gather in wireless sensor and ad-hoc networks. The type system enjoys the usual property of subject reduction, meaning that well-typed processes reduce to well-typed processes. To cope with unreliability, we also introduce a notion of process recovery that does not involve communication. This is the first session type system for a model with unreliable communication.

Exposición de los trabajos de investigación más destacados del ciclo 2021-2, por los alumnos de la Facultad de Administración en Hotelería y Turismo.

Participation in summer session has benefits for students including improved retention and degree completion and increased contact with faculty (Adelman, 2006; DiGregorio, 1998). Just as some characteristics of students limit their access to participate in higher education in general, participation in summer session may also be affected by certain student characteristics. This study used a nationally representative sample to explore how undergraduate students who enroll in summer session may differ from undergraduate students who do not enroll in summer session in a variety of financial, geographic, academic, programmatic and cultural/social/physical characteristics historically associated with access to higher education. Significant differences between summer enrolled and not enrolled students were found in a number of instances. Some characteristics that are negatively associated with enrollment, persistence and attainment in higher education were positively associated with summer enrollment. A regression analysis revealed that the combined predictive value of student characteristics accounts for only a small portion of the overall decision to enroll in the summer term. / Ph. D.