Application of bus emulation techniques to the design of a PCI/MC68000 bridge

Bridges easy the interconnection and communication of devices that operate using different buses. In fact, we can see a computer as a hierarchy of buses to which devices are connected. In this paper we design a PCI/MC68000 bridge in order to improve communications between a Personal Computer and a MC68000 based system. The previous interface between both devices was based on the old 16-bit ISA bus, which represented a bottleneck in their communication. However, the methodology described here is generic and can be applied to the design of PCI bridges to other buses. We finish this work with an analysis of the bridge performance improvement which can also be easily adapted to other situations. As an example our interface is used in an interesting situation, i.e., updating the obsolete control unit of a highly valuable system (an industrial robot)

Exploring performance and power properties of modern multicore chips via simple machine models

Modern multicore chips show complex behavior with respect to performance and power. Starting with the Intel Sandy Bridge processor, it has become possible to directly measure the power dissipation of a CPU chip and correlate this data with the performance properties of the running code. Going beyond a simple bottleneck analysis, we employ the recently published Execution-Cache-Memory (ECM) model to describe the single- and multi-core performance of streaming kernels. The model refines the well-known roofline model, since it can predict the scaling and the saturation behavior of bandwidth-limited loop kernels on a multicore chip. The saturation point is especially relevant for considerations of energy consumption. From power dissipation measurements of benchmark programs with vastly different requirements to the hardware, we derive a simple, phenomenological power model for the Sandy Bridge processor. Together with the ECM model, we are able to explain many peculiarities in the performance and power behavior of multicore processors, and derive guidelines for energy-efficient execution of parallel programs. Finally, we show that the ECM and power models can be successfully used to describe the scaling and power behavior of a lattice-Boltzmann flow solver code.Comment: 23 pages, 10 figures. Typos corrected, DOI adde

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Department of Urban and Environmental Engineering (Disaster Management Engineering)Seismic risk assessment has recently emerged as an important issue for infrastructure systems because of their vulnerability to seismic hazards. Earthquakes can have significant impacts on transportation networks such as bridge collapse and the resulting disconnections in a network. One of the main concerns is the accurate estimation of the seismic risk caused by the physical damage of bridges and the reduced performance of the associated transportation network. This requires estimating the performance of a bridge transportation network at the system level. Moreover, it is necessary to deal with various possible earthquake scenarios and the associated damage states of component bridges considering the uncertainty of earthquake locations and magnitudes. To perform the seismic risk assessment of a bridge transportation network, system reliability is required. It is a challenging task for several reasons. First, the seismic risk itself contains a great deal of uncertainty, which comprises location, magnitude, and the resulting intensity of possible earthquakes in a target network. Second, the system performance of a bridge transportation network after the seismic event needs to be estimated accurately, especially for realistic and complex networks. Third, the seismic risk assessment employing system reliability may increase the computational costs and can be time-consuming tasks, because it requires dealing with various possible earthquake scenarios and the resulting seismic fragility of component bridges. Fourth, a precise performance measure of the system needs to be introduced. In this study, a new method is proposed to assess the system-level seismic risk of bridge transportation networks considering earthquake uncertainty. In addition, a new performance measure is developed to help risk-informed decision-making regarding seismic hazard mitigation and disaster management. For the tasks, first of all, a matrix-based system reliability framework is developed, which performs the estimation of a bridge transportation network subjected to earthquakes. Probabilistic seismic hazard analysis (PSHA) is introduced to enable the seismic fragility estimation of the component bridges, considering the uncertainty of earthquake locations and magnitudes. This is systemically used to carry out a post-hazard bridge network flow analysis by employing the matrix-based framework. Secondly, two different network performance measures are used to quantify the network performance after a seismic event. Maximum flow capacity was originally used for a bridge transportation network, however the numerical example using this measure is further developed for applications to more accurate system performance analysis using total system travel time (TSTT). Finally, a new method for system-level seismic risk assessment is proposed to carry out a bridge network flow analysis based on TSTT by employing the matrix-based system reliability (MSR) method. In the proposed method, the artificial neuron network (ANN) is introduced to approximate the network performance, which can reduce the computational cost of network analysis. The proposed method can provide statistical moments of the network performance and component importance measures, which can be used by decision-makers to reduce the seismic risk of a target area. The proposed method is tested by application to a numerical example of an actual transportation network in South Korea. In the seismic risk assessment of the example, PSHA is successfully integrated with the matrix-based framework to perform system reliability analysis in a computationally efficient manner.clos

Advancing Bridge Technology, Task 10: Statistical Analysis and Modeling of US Concrete Highway Bridge Deck Performance -- Internal Final Report

Concrete highway bridge deck repairs represent the highest expense associated with bridge maintenance cost. In order to optimize such activities and use the available monies effectively, a solid understanding of the parameters that affect the performance of concrete bridge decks is critical. The National Bridge Inventory (NBI), perhaps the single-most comprehensive source of bridge information, gathers data on more than 600,000 bridges in all fifty states, the District of Columbia, and the Commonwealth of Puerto Rico. Focusing on concrete highway bridge deck performance, this research developed a nationwide database based on NBI data and other critical parameters that were computed by the authors, referred to as the Nationwide Concrete Highway Bridge Deck Performance Inventory (NCBDPI) database. Additionally, two performance parameters were computed from the available concrete bridge deck condition ratings (CR): Time-in-condition rating (TICR) and deterioration rate (DR). Following the aggregation of all these parameters in the NCBDPI database, filtering, and processing were performed. In addition to a basic prescriptive analysis, two types of advanced analysis were applied to the new dataset. First, binary logistic regression was applied to a subset of the data consisting of the highest and lowest DR. Second, a Bayesian survival analysis was performed on the TICR considering censored data. Through the analyses it was possible to show which parameters influence deck performance and create tools that can help agencies and bridge owners make better decisions regarding concrete bridge deck preservation

Performance Practice Versus Performance Analysis: Why Should Performers Study Performance

RILM abstract: The descriptive study of performance analysis and performance history differs from the usually prescriptive field of performance practice. The investigation of musical performance can be divided into three layers: general period and geographic styles, the traditions which become attached to specific works, and individual innovations. Features of the first two are transparent to performers and listeners from the same period, but they determine most of the features of a performance. Performance style is like a linguistic accent; we can no more let the music speak for itself than we can speak words without some accent. Since performance traditions and the ideology of interpretation are tied to a number of cultural variables, the study of music in performance forms an important bridge between the formal analysis of works and cultural studies

Damage analysis and seismic retrofitting of a continuous prestressed reinforced concrete bridge

SummaryThe seismic analysis and retrofit of prestressed reinforced concrete bridge is discussed by considering a real case of a viaduct still in use. The unique features of this bridge make this type of bridge particularly interesting, either structurally or architecturally. The paper begins with the analysis of certain particular structural deficiencies that emerged during the viaduct operation. The results of the analysis indicate that the structural performance can be enhanced by only modifying the support devices. The primary structural components are not required to be involved in the retrofitting process. Using the modern seismic code, the upgrading of the viaduct performance is obtained by replacing the old bearing devices on the piers and existing viscous dampers connected abutments to the deck with new modernised ones

Generalized small-signal modelling of dual active bridge DC/DC converter

this paper presents a novel generalised approach of the small-signal modelling of dual active bridge (DAB) DC/DC converter. The adopted analysis is based on a per-unit fundamental frequency representation of the DAB. The outcome of the proposed modelling approach is a small signal, linearised, state-space DAB model; which is considered as a main building block for future control applications. The developed small signal DAB model includes all possible degrees of freedom affecting the performance of the DAB; this includes the voltage conversion ratio to allow the study of all DAB operation modes (i.e.: unity-gain and buck/boost modes.). Furthermore, since triple phase shift control (TPS) is used in this development work, the proposed model incorporates phase shift in addition to duty ratios. This feature allows for bridge voltage regulation, which is essential for efficient DAB operation in the case of buck/boost operation. Another key achievement is that the proposed small signal modelling methodology can be applied to any bidirectional DC-DC converter regardless of ratings, parameter values and number of ports. Extensive simulation is carried out to verify the proposed analysis

Wind-induced vibration analysis of the Hong Kong Ting Kau Bridge

Because of their high flexibility and relatively low structural damping, long-span bridges are prone to wind-induced vibration. An efficient wind field simulation technique for wind-induced vibration analysis of long-span bridges is first introduced in this paper. The time-domain expressions for the buffeting and self-excited forces acting on long-span bridges can then be found from the wind velocities. Based on the above theory and the aerodynamic parameters obtained by wind tunnel tests, a study of the wind fluctuations and aerodynamic forces is carried out on the Hong Kong Ting Kau Bridge, which is a cable-stayed bridge comprising two main spans and two side spans. The buffeting response of the bridge is analysed in the time domain by using step-by-step numerical integration techniques. The aerodynamic behaviour of the bridge can therefore be obtained, and the safety performance of the bridge against strong wind can further be evaluated. Numerical results basically agree with the experimental data, indicating that the theory presented in this paper is applicable to engineering practice.published_or_final_versio