In this paper, we propose a novel graph representation, Railway Visualization, to reveal the information evolution with temporal relationship over time. Through Railway Visualization, it cannot only reveal the changes of an entity’s intra-state over time, but also can effectively disclose the intrinsic characteristics of the complicated relationship evolution, such as branching, crossing, split...

Risk assessment is becoming increasingly important for railway signal system in order to safeguard their passengers and employees while improving safety and reducing maintenance costs. However, the application of risk assessment methods in railway signal system may not give satisfactory results because the risk data are incomplete or there is a high level of uncertainty involved in the risk dat...

Risk management is becoming increasingly important for railway companies in order to safeguard their passengers and employees while improving safety and reducing maintenance costs. However, in many circumstances, the application of probabilistic risk analysis tools may not give satisfactory results because the risk data are incomplete or there is a high level of uncertainty involved in the risk...

In this paper, we propose to reduce the MAC overheads in random access protocols by partitioning the channel spectrum used into a narrow channel and a wide channel. The narrow channel is used for transmitting the short packets (approximately 100 bytes long) and the wide channel is used for transmitting the longer packets. We intend to use multiple radios, one each for the different channel part...

Current partitioning codesign tools often simplify the communication channel features by working with generic abstract channels, which in a following step, are mapped into the actual ones. However, this mapping process can critically affect the performance of a solution. Hence, we have developed a novel methodology that studies the communications in depth, taking into account the actual channel...

Keeping up with modern high-bandwidth networks is a significant challenge for system designers. A key obstacle to high network throughput is the high overhead of communication between the CPU and network interface controller (NIC), which typically resides on a standard I/O bus with high access latency. We investigate the impact of this overhead by analyzing the performance of hypothetical syste...

In most contemporary systems there are several jobs concurrently competing for shared resources, such as a processor, memory, network, sensors or other devices. Sharing a resource between several jobs requires synchronizing the jobs, specifying when which job will have access to the resource. A common synchronization method is scheduling. Executing a schedule requires switching resource assignm...

In concurrent computing environments based on heterogeneous processing elements interconnected by general-purpose networks, several classes of overheads contribute to lowered performance. The most obvious limitations are network throughput and latency, but certain other factors also play a significant role. In an attempt to gain some insight into the nature of these overheads, and to propose st...

This dissertation research addresses overheads in supporting virtual memory, especially virtual-to-physical address translation overheads (i.e., performance, power, and energy) via a Translation Lookaside Buffer (TLB). To overcome the overheads, we revisit virtually indexed, virtually tagged caches. In practice, they have not been common in commercial microarchitecture designs, and the crux of ...

To develop a good parallel implementation requires understanding of where run-time is spent and comparing this to some realistic best possible time. We introduce “overhead analysis” as a way of comparing achieved performance with achievable performance. We present a tool, OVALTINE, which aims to provide, automatically, the user with a hierarchical set of overheads for a given OpenMP implementat...