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Virtualization is fundamental to cloud computing because it allows multiple operating systems to run simultaneously on a physical machine. However, it also brings a range of security/privacy problems. One particularly challenging and important problem is: how can we protect the Virtual Machines (VMs) from being attacked by Virtual Machine Monitors (VMMs) and/or by the cloud vendors when they are not trusted? In this paper, we propose an architectural solution to the above problem in multi-processor cloud environments. Our key idea is to exploit hardware mechanisms to enforce access control over the shared resources (e.g., memory spaces), while protecting VM memory integrity as well as inter-processor communications and data sharing. We evaluate the solution using full-system emulation and cycle-based architecture models. Experiments based on 20 benchmark applications show that the performance overhead is 1.5%-10% when access control is enforced, and 9%-19% when VM memory is encrypted.

Container terminals (CTs) play an essential role in the global transportation system. To deal with growing container shipments, a CT needs to better solve the three essential seaside operational problems; berth allocation problem (BAP), quay crane assignment problem (QCAP), and quay crane scheduling problem (QCSP), which affect the performance of a CT considerably. In past studies, the three seaside operational problems have often been solved individually or partially, which is likely to result in poor overall system performance. However, solving the three seaside operational problems simultaneously is in fact a very complicated task. In this research, we dealt with the three seaside operational problems at the same time by using a novel high-level Petri net, termed an Object-Oriented and Timed Predicate/Transition Net (OOTPr/Tr net). After defining the three seaside operational problems formally, we integrated them as a three-level framework that was further transformed into an OOTPr/Tr net model. Then, using the Prolog programming language, we implemented this model as a simulation tool to find the best solution based on the various combinations of heuristic rules used.

Efficiently discovering services in terms of diversified service constraints in a dense MANET is a challenging issue. This paper proposes to build a distributed suffix tree on backbone nodes as XMLbased services' index to provide a concise profile for service descriptions. Moreover, a content-addressable P2P overlay and corresponding fault-tolerance mechanisms are introduced to support the distributed suffix tree and deal with the changes in network topology. In such a way, the precision and recall for service discovery are guaranteed and can also be degraded gracefully in the face of node failures. Experimental results show that our approach can increase at least 30% precision in comparison with existing distributed index solutions, and our newlyadded messages for every 100 queries are only 22% as many as the ones of the compared solutions.

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