Optimizing NUCA organizations and wiring alternatives for large caches with CACTI 6.0

Journal ArticleA significant part of future microprocessor real estate will be dedicated to L2 or L3 caches. These on-chip caches will heavily impact processor performance, power dissipation, and thermal management strategies. There are a number of interconnect design considerations that influence power/performance/area characteristics of large caches, such as wire models (width/spacing/repeaters), signaling strategy (RC/differential/transmission), router design, etc. Yet, to date, there exists no analytical tool that takes all of these parameters into account to carry out a design space exploration for large caches and estimate an optimal organization. In this work, we implement two major extensions to the CACTI cache modeling tool that focus on interconnect design for a large cache. First, we add the ability to model different types of wires, such as RC-based wires with different power/delay characteristics and differential low-swing buses. Second, we add the ability to model Non-uniform Cache Access (NUCA). We not only adopt state-of-the-art design space exploration strategies for NUCA, we also enhance this exploration by considering on-chip network contention and a wider spectrum of wiring and routing choices. We present a validation analysis of the new tool (to be released as CACTI 6.0) and present a case study to showcase how the tool can improve architecture research methodologies

Model Seakeeping Experiments Presented in the Time-Domain to Facilitate Validation of Computational Tools

The purpose of Model Seakeeping Experiments Presented in the Time-Domain to Facilitate Validation of Computational Tools has been to put together a well-arranged bank of model measurements, useful as a reference material in the validation procedure of real-time simulation models. The work reports on seakeeping experiments on a model of an 11300 tonne ro-ro vessel. All information is at hand: hull geometry, model condition, test set-up, procedures and time series of the measured quantities. The time series, together with the hull geometry, is stored on CD-ROM. The printed part of the work reports on the test set-up, procedures and post-processing, and gives a catalogue with overall data on each test. Experiments were performed in regular, irregular and short-crested waves at two speeds, corresponding to five and 15 knots, with relative heading varied around the clock. The wave systems were modelled by regular waves with amplitude corresponding to one-three metre and of irregular waves with significant wave height of five metre. For each test, the waves are described by an analytical expression. Those wave equations describing the wave elevation in time and space, can be used as sea environment when comparing the measurements with time-domain simulations. The recorded data are from measurements of wave elevation, global and local motion, velocity and acceleration. Each of the 110 tests are described by time series recorded from 18 measurement channels. Thanks to the generality of the tests and the accessibility of hull geometry and time series, the work should be useful not only as reference in cases of validation, but also to illustrate the dynamic behaviour of ships in the education of naval architects

Modeling of planing craft in waves

Simulation of the planing hull in waves has been addressed during the last 25 years and basically been approached by strip methods. This work follows that tradition and describes a time-domain strip model for simulation of the planing hull in waves. The actual fluid mechanical problem is simplified through the strip approach. The load distribution acting on the hull is approximated by determining the section load at a number of hull sections, strips. The section-wise 2-dimensional calculations are expressed in terms of added mass coefficients and used in the formulations of both inertia and excitation forces in the equations of motions. The modeling approach starts from the hypothetic assumption that the transient conditions can be modeled based on those section-wise calculations. The equation of motion is solved in the time-domain. The equation is up-dated at each time step and every iteration step with respect to the momentary distribution of section draught and relative incident velocity between the hull and water and catches the characteristic non-linear behavior of the planing craft in waves. The model follows the principles of the pioneering work of E. E. Zarnick differing on model structure and in details such as the modeling of the lift in the transom area. A major part of the work is concerned with experiments and evaluation of simulations with respect to performed model tests and to published experiment data. Simulations of model tests have been performed and comparisons have been made between measured and simulated time series. The link between simulation and experiment is a wave model which is based on a wave height measurement signal. It is developed and evaluated in the thesis. The conclusions are in favor of the 2-dimensional approach to modeling the conditions for the planing hull in waves and among further studies is evaluation of simulated loads and motions to full-scale trial measurement data

Modeling of planing craft in waves

Simulation of the planing hull in waves has been addressed during the last 25 years and basically been approached by strip methods. This work follows that tradition and describes a time-domain strip model for simulation of the planing hull in waves. The actual fluid mechanical problem is simplified through the strip approach. The load distribution acting on the hull is approximated by determining the section load at a number of hull sections, strips. The section-wise 2-dimensional calculations are expressed in terms of added mass coefficients and used in the formulations of both inertia and excitation forces in the equations of motions. The modeling approach starts from the hypothetic assumption that the transient conditions can be modeled based on those section-wise calculations. The equation of motion is solved in the time-domain. The equation is up-dated at each time step and every iteration step with respect to the momentary distribution of section draught and relative incident velocity between the hull and water and catches the characteristic non-linear behavior of the planing craft in waves. The model follows the principles of the pioneering work of E. E. Zarnick differing on model structure and in details such as the modeling of the lift in the transom area. A major part of the work is concerned with experiments and evaluation of simulations with respect to performed model tests and to published experiment data. Simulations of model tests have been performed and comparisons have been made between measured and simulated time series. The link between simulation and experiment is a wave model which is based on a wave height measurement signal. It is developed and evaluated in the thesis. The conclusions are in favor of the 2-dimensional approach to modeling the conditions for the planing hull in waves and among further studies is evaluation of simulated loads and motions to full-scale trial measurement data

Model Seakeeping Experiments Presented in the Time-Domain to Facilitate Validation of Computational Tools

The purpose of Model Seakeeping Experiments Presented in the Time-Domain to Facilitate Validation of Computational Tools has been to put together a well-arranged bank of model measurements, useful as a reference material in the validation procedure of real-time simulation models. The work reports on seakeeping experiments on a model of an 11300 tonne ro-ro vessel. All information is at hand: hull geometry, model condition, test set-up, procedures and time series of the measured quantities. The time series, together with the hull geometry, is stored on CD-ROM. The printed part of the work reports on the test set-up, procedures and post-processing, and gives a catalogue with overall data on each test. Experiments were performed in regular, irregular and short-crested waves at two speeds, corresponding to five and 15 knots, with relative heading varied around the clock. The wave systems were modelled by regular waves with amplitude corresponding to one-three metre and of irregular waves with significant wave height of five metre. For each test, the waves are described by an analytical expression. Those wave equations describing the wave elevation in time and space, can be used as sea environment when comparing the measurements with time-domain simulations. The recorded data are from measurements of wave elevation, global and local motion, velocity and acceleration. Each of the 110 tests are described by time series recorded from 18 measurement channels. Thanks to the generality of the tests and the accessibility of hull geometry and time series, the work should be useful not only as reference in cases of validation, but also to illustrate the dynamic behaviour of ships in the education of naval architects

Fuzzy AHP-Based Design Performance Index for Evaluation of Ferries

Within waterborne public transportation (WPT), one often observes a mismatch between the operational requirements and ferry characteristics. A method to holistically evaluate ferries with respect to local requirements could lead to tailored procurement and targeted refurbishment of existing fleet. In this study, we develop a structure for operational requirements and use it as a basis for a ferry evaluation methodology. The requirements’ structure follows a three-level hierarchy starting from broad vessel design to mandatory requirements to performance requirements. The performance requirements are based on the three pillars of sustainability, aided by commuter surveys carried out in Stockholm ferries, interviews with public transport providers (PTP) and previous literature. The evaluation of the ferry is performed using analytic hierarchic process (AHP) to convert the PTP’s subjective preferences and ferry performance into a single dimensionless index. Rules for quantification of performance metrics including social performance are proposed. The uncertainties associated with AHP are addressed by employing fuzzy AHP based on extent analysis and fuzzy AHP in combination with particle swarm optimization. Two applications including performance assessment of existing ferries and assembly of a modular ferry are discussed. The method can lead to objective decision making in ferry evaluation, potentially leading to a more efficient WPT

A modularly tailored commuter ferry platform

Among the challenges for implementation of Waterborne public transportation (WPT) are the difficulties in procuring efficient ferries tailored towards local requirements. Fundamental questions on the ferry’s environmental impact, speed and procurement costs linger in the public transport (PTP) mind. In this paper, a methodology for adopting a platform architecture for ferries is illustrated by a modular design approach. For this, WPT operational profiles are categorized by three route types in a structure for operational requirements including sustainability performance. Generic parameters for size and speed of WPT ferries are defined. Using these parameters as a skeletal structure, a modular commuter ferry concept is proposed as a set of basic modules. As a combination of these functionally independent modules, a ferry can be tailored to fit the operational requirements. The paper proposes standard sizes for waterborne commuter craft and shows that ferries are compatible with land-based public transport in terms of energy efficiency and speed. Suitable speed ranges for mono hulls and catamarans are investigated and the idea of modular design for rational procurement is explored and illustrated for the three type routes. The proposed concepts can make WPT more attractive for PTPs as a sustainable option to complement the existing network.QC 20220518</p

1883-1886, Frederick Robie

Frederick Robie of Gorham, Governor 1883-1886.https://digitalmaine.com/arc_govportraits/1035/thumbnail.jp

Monitoring and characterization of vibration and shock conditions aboard high-performance marine craft

The stochastic environmental conditions together with craft design and operational characteristics make it difficult to predict the vibration environments aboard high-performance marine craft, particularly the risk of impact acceleration events and the shock component of the exposure often being associated with structural failure and human injuries. The different timescales and the magnitudes involved complicate the real-time analysis of vibration and shock conditions aboard these craft. The article introduces a new measure, severity index, indicating the risk of severe impact acceleration, and proposes a method for real-time feedback on the severity of impact exposure together with accumulated vibration exposure. The method analyzes the immediate 60s of vibration exposure history and computes the severity of impact exposure as for the present state based on severity index. The severity index probes the characteristic of the present acceleration stochastic process, that is, the risk of an upcoming heavy impact, and serves as an alert to the crew. The accumulated vibration exposure, important for mapping and logging the crew exposure, is determined by the ISO 2631:1997 vibration dose value. The severity due to the impact and accumulated vibration exposure is communicated to the crew every second as a color-coded indicator: green, yellow and red, representing low, medium and high, based on defined impact and dose limits. The severity index and feedback method are developed and validated by a data set of 27 three-hour simulations of a planning craft in irregular waves and verified for its feasibility in real-world applications by full-scale acceleration data recorded aboard high-speed planing craft in operation.This research is funded by the Gösta Lundeqvist foundation for ship research (Gösta Lundeqvists stiftelse för skeppsteknisk forskning) and the Swedish Maritime Administration (Sjöfartsverket). QC 20191001</p

Slutrapport för Vattenvägen 365

Huvudsyftet med projektet Vattenvägen 365 är att utröna om och i så fall hur vattenvägen kan bidra till hållbar mobilitet och ökad transportkapacitet. Utgångspunkten är den initiala systemanalys som identifierade relevanta forskningsfrågor och tekniska nyckelutmaningar kritiska för att kunna använda vattenvägen som en infrastrukturresurs för kollektivtrafik och citylogistik 365 dagar om året. Genom en systematisk process identifierades frågor och utmaningar som kategoriserades i tolv sektorer. Nu i projektets andra steg är strategin att i olika sammanhang aktivt framhålla systemperspektivet och den helhetsbild som de tolv identifierade sektorerna utgör. Utöver helhetsöverblicken, som går under benämningen Navet, prioriterades sektorerna Lightweight design for sustainability, samt Utvärderingsmetoder för systemprestanda. Projektet rapporteras genom årsrapporter och en rad andra konkreta avtalade leverabler. Projektet följer planen och rapporterar här en sammanfattning av verksamhet och delresultat där vi står nu i halvårsskiftet 2017. Rapporten betonar de omfattande Navaktiviteterna men vi konstaterar att delstudien LightIce avslutades som planerat under 2016 och resultat från projektet presenterades under rubrikerna Light weight vessels operation in brashed ice vid International conference of Sandwich Structures, ICSS-16 Florida Atlantic University, USA (Bilaga 1) och Experimental investigation of an accidental ice impact on an aluminium high speed craft vid International Conference on Marine Structures Marstruct2017. Samarbetet med Hamburgs Tekniska Universitet, TUHH, kring lättviktsdesign och islaster som hade sin tyngdpunkt på experimentella studier av islaster på aluminiumstrukturer sammanfattas i den artikel som publicerades i samband med Marstruct2017 (Bilaga 2). Samarbetet mellan KTH och TUHH som påbörjades inom VV365/LightIce fortsätter nu inom ett arbetspaket i EU-interregprojektet EMMA.KTH/Vattenbussen Vattenvägen 36