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We present TerrainLOS, an outdoor propagation model that uses Digital Elevation Models to determine whether two nodes can communicate. We have implemented TerrainLOS in the sensor network simulator COOJA and used it to evaluate how the roughness of terrain, which we classify using Average Cumulative Visibility, affects the number of edges, connectedness, latency, and power of a network. We compare...
Energy consumption of today's datacenters is a constant concern from the standpoints of monetary and environmental costs. We model a datacenter as a queueing system, where each server can be switched on or off, with the time to switch a server on being nonnegligible. Previously derived structural properties of the optimal policy allow us to intelligently select policies to analyse further. Using the...
Millimeter wave (mmWave) is one of the key technologies in the fifth-generation (5G) wireless system, providing abundant spectrum resources to meet the ever-increasing wireless connections and a huge volume of data traffic. Nowadays, many experts and scholars in this field are focusing on the relationship between channel modeling and system performances of mmWave cellular networks. In this paper,...
Tuning large applications requires a clever exploration of the design and configuration space. Especially on supercomputers, this space is so large that its exhaustive traversal via performance experiments becomes too expensive, if not impossible. Manually creating analytical performance models provides insights into optimization opportunities but is extremely laborious if done for applications of...
Deduplication has been widely used to improve storage efficiency in modern primary and secondary storage systems, yet how deduplication fundamentally affects storage system reliability remains debatable. This paper aims to analyze and compare storage system reliability with and without deduplication in primary workloads using real-world file system snapshots. Specifically, we propose a trace-driven,...
In Long Term Evolution (LTE) networks, User Equipments (UE)s should proceed Random Access CHannel (RACH) procedure to attach to the Base Station and access the channel. One limitation of this procedure is the congestion that may appear when high number of UEs are simultaneously trying to attach to the channel. Such use-case happens when high number of Machine Type Communication (MTC) devices are deployed...
User activity in five mobile games is found to be accurately described by stochastic processes related to recurrent event models in survival analysis. We specify four simple parametric models and methods to fit them to data which specify this process within day accuracy in the individual user level. This model implies commonly used population level retention metrics: retention, rolling retention and...
Currently, Business Process Model and Notation (BPMN) has becoming one of the main languages for creating a description of processes and developing executable frameworks for the management of the process itself. In this context, one important aspect of process management is the possibility of process analysis and optimization, which many times relies on real data collected during the process execution...
The analysis and comparison of open source software can be improved by means of quality models supporting the evaluation of the software systems being compared and the final decision about which of them has to be adopted. Since software quality can mean different things in different scenarios, quality models should be flexible in order to accommodate the needs of different users. Over the years several...
In this paper, we present a combined experimental and analytical investigation of the impact of security compliance on a three-tier web application hosted on a virtualized platform. We used two-group experimental design for our experiments, and analyzed the impact of security using the ANCOVA model. The results of experiments suggest that security measures have significant impact on system performance...
Communication in social networking has become an important part of life for most modern people. Sometimes people do not even think that interacting with other users, as well as sharing their views and interests online, they create a virtual circle of friends, uniting people with similar interests. Information about these user groups is very important, for example in the statistical analysis. The info...
Along with the development of split-share reform and capital market, the trend of equity decentralization in listed companies is becoming more and more obvious. Professional managers' betrayal of large shareholders frequently occurs, which leads to the competing for corporate control between executives and shareholders. This paper studies on the corporate control from the perspective of competing...
Complex network analysis has become a critical research area for the design and evaluation of complex systems, due to the increasing success of modeled phenomena. Accordingly, there is a growing need for easy-to-use and fast network analysis software packages. In this work, we report on a comprehensive benchmark of state-of-the-art network analysis software. We perform exhaustive experiments on a...
Residual stress of thin-walled blanks with complex cavity structure is an important influence factor on the stability of machining. The most residual stress testing technologies is only suitable to measure residual stress of surface or shallow surface. It is difficult to ensure the accuracy to measure residual stress inside workpiece. In order to study the reliability and accuracy of incremental hole...
Accidents on petroleum installations can have huge consequences, to mitigate the risk, a number of safety barriers are devised. Faults and unexpected events may cause barriers to temporarily deviate from their nominal state. For safety reasons, a work permit process is in place: decision makers accept or reject work permits based on the current state of barriers. However, this is difficult to estimate,...
The Program Vulnerability Factor (PVF) has been proposed as a metric to understand the impact of hardware faults on software. The PVF is calculated by identifying the program bits required for architecturally correct execution (ACE bits). PVF, however, is conservative as it assumes that all erroneous executions are a major concern, not just those that result in silent data corruptions, and it also...
Concepts such as price, performance, time to completion (availability), probability of failure and nonrepudiation are key to developing a comparison service in order to establish Service Level Agreements (SLA) or design better mechanisms to improve performance in Cloud Computing Systems (CCS). This work presents our design of a performance analysis platform that includes an infrastructure, a framework...
A Mobile Ad-hoc Network is a flexible wireless network. The nodes also function as routers which determine and propagate the routing tables amongst their neighbours to ensure a destination can be reached in the network. Without the restraint of physical links, mobility is common, these connections are not necessarily constant, with nodes free to either leave or join the network. This paper presents...
This paper proposes a novel and highly scalable multistage packet-switch design based on Networks-on-Chip (NoC). In particular, we describe a three-stage Clos packet-switch fabric with a Round-Robin packets dispatching scheme where each central stage module is an Output-Queued Unidirectional NoC (OQ-UDN), instead of the conventional single-hop crossbar. We test the switch performance under different...
The effects caused by variability, temperature, radiation or aging may compromise the reliability of electronic circuits. Circuits designers must consider their combined effects early during the design cycle, even though it is a time and effort demanding task. In this work we present a methodology and simulation framework for the reliable design of circuits working under realistic conditions such...
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