Learning Queuing Networks by Recurrent Neural Networks

It is well known that building analytical performance models in practice is difficult because it requires a considerable degree of proficiency in the underlying mathematics. In this paper, we propose a machine-learning approach to derive performance models from data. We focus on queuing networks, and crucially exploit a deterministic approximation of their average dynamics in terms of a compact system of ordinary differential equations. We encode these equations into a recurrent neural network whose weights can be directly related to model parameters. This allows for an interpretable structure of the neural network, which can be trained from system measurements to yield a white-box parameterized model that can be used for prediction purposes such as what-if analyses and capacity planning. Using synthetic models as well as a real case study of a load-balancing system, we show the effectiveness of our technique in yielding models with high predictive power

Radiobiological effects of wound fluid on breast cancer cell lines and human-derived tumor spheroids in 2D and microfluidic culture

Intraoperative radiotherapy (IORT) could abrogate cancer recurrences, but the underlying mechanisms are unclear. To clarify the effects of IORT-induced wound fluid on tumor progression, we treated breast cancer cell lines and human-derived tumor spheroids in 2D and microfluidic cell culture systems, respectively. The viability, migration, and invasion of the cells under treatment of IORT-induced wound fluid (WF-RT) and the cells under surgery-induced wound fluid (WF) were compared. Our findings showed that cell viability was increased in spheroids under both WF treatments, whereas viability of the cell lines depended on the type of cells and incubation times. Both WFs significantly increased sub-G1 and arrested the cells in G0/G1 phases associated with increased P16 and P21 expression levels. The expression level of Caspase 3 in both cell culture systems and for both WF-treated groups was significantly increased. Furthermore, our results revealed that although the migration was increased in both systems of WF-treated cells compared to cell culture media-treated cells, E-cadherin expression was significantly increased only in the WF-RT group. In conclusion, WF-RT could not effectively inhibit tumor progression in an ex vivo tumor-on-chip model. Moreover, our data suggest that a microfluidic system could be a suitable 3D system to mimic in vivo tumor conditions than 2D cell culture

A Framework for Improving Systems Performance by Minimizing Burstiness

The principal goal of this work is to support performance management for systems that utilize resources in complex ways. Typically, performance evaluation has been carried out for such systems using simulation tools. However, such tools require expert model builders to create and maintain abstract business process models of the system under study. This can lead to a lack of representativeness, specifically, when many unique scenarios are to be modelled. This thesis presents a new simulation approach, Simulation By Example, which guides the simulation directly using events extracted from traces, i.e., examples. This work demonstrates and evaluates this new approach using three case studies from healthcare systems. These studies establish the advantages of SBE over traditional simulation methods and its ability to support a variety of performance management exercises. Next, this thesis focuses on improving the performance of systems subjected to bursty workloads. Burstiness in resource service demands has previously been shown to have an adverse impact on system performance. This thesis proposes AMIR, an Analytic Method for Improving Responsiveness by reducing burstiness. AMIR considers a system with multiple classes of users and multiple resources that service user sessions in tandem. Batch processing systems, fabrication and manufacturing environments, micro-service systems, and patient operating rooms can be described in this way. Given the service demands distributions placed by all classes for the system's resources and the number of session arrivals for each class, AMIR decides an ordering of sessions that minimizes burstiness and improves system responsiveness metrics including session wait time, and total schedule processing time. A key aspect of the technique is an order O schedule burstiness metric β^O, which represents the mean joint probability that O+1 consecutive sessions in the schedule have resource demands at the bottleneck resource greater than the mean bottleneck resource demand of the schedule. For a given O, AMIR uses integer linear programming to produce schedules that progressively minimize β^i for all i in {1,...O}. Extensive simulation results show that AMIR significantly outperforms baseline policies such as shortest first and random scheduling. The results also provide insights on the conditions under which the technique is most effective

Dec: a technique for estimating resource demands of software services

Bibliography: p. 84-90Some pages are in colour

A Review of Abdullah Ibn Salam's Position during the Period of Prophet and Caliphs

The historical narratives demonstrate that Ibn Salam became Muslim in the first year of Hejrat. Nevertheless, he did not play a significant role in the battles and remarkable events during the period of Prophet. After the death of Prophet, he became an influential character by approaching to the government. Subsequently, he had the permit for narrating the traditions in the period of the prohibition of Hadith and also defended the Caliphs' performance especially in the revolt against Osman. Moreover, the Caliphs and Bani Omayeh endeavored to promote the religious and political position of Ibn Salam in society by means such as the replacement of unauthentic religious authorities instead of prophet's family i.e. Imam Ali, claim of some verses describing the faith of Ibn salam and fictitious traditions to admire him. The purpose of Bani Omayeh for supporting Ibn salam was to obtain public consideration and to strengthen its legitimacy. Such policy had effects on scholars who made mistake interpretation about Ibn Salam's character. Consequently, they narrated the inaccurate verses about him