Marc Pons

VCTA: A Via-Configurable Transistor Array regular fabric

Layout regularity is introduced progressively by integrated circuit manufacturers to reduce the increasing systematic process variations in the deep sub-micron era. In this paper we focus on a scenario where layout regularity must be pushed to the limit to deal with severe systematic process variations in future technology nodes. With this objective, we propose and evaluate a new regular layout style called Via-Configurable Transistor Array (VCTA) that maximizes regularity at device and interconnect levels. In order to assess VCTA maximum layout regularity tradeoffs, we implement 32-bit adders in the 90 nm technology node for VCTA and compare them with implementations that make use of standard cells. For this purpose we study the impact of photolithography proximity and coma effects on channel length variations, and the impact of shallow trench isolation mechanical stress on threshold voltage variations. We demonstrate that both variations, that are important sources of energy and delay circuit variability, are minimized through VCTA regularity.

A georeferenced agent-based model to analyze the climate change impacts on ski tourism at a regional scale

One main argument for modeling socio-ecological systems is to advance the understanding of dynamic correlations between various human and environmental factors, including impacts and responses to environmental change. We explore the shift in skier distribution among ski resorts taking into account the behavioral adaptation of individuals due to the impact of climate change on snow conditions. This analysis is performed at a regional scale by means of a coupled gravity and georeferenced agent-based model. Four different scenarios are considered. Two scenarios assume an increase of winter mean temperature of +2°C and +4°C, respectively, taking into account only natural snow conditions. Two additional scenarios add the effect of snowmaking to enhance the natural snow depth and extend the skiing season in the +2°C and +4°C base scenarios. Results show differing vulnerability levels, allowing the classification of ski resorts into three distinct groups: (1) highly vulnerable ski resorts with a strong reduction in visitors attendance for all climate change scenarios, characterized by unfavorable geographical and attractiveness conditions, making it difficult to ensure snow availability in the future; (2) low vulnerability ski resorts, with moderate reduction in season length during a high climate change scenario but no reduction (or even an increase) in a low one, characterized by ski resorts with a medium capacity and attractiveness to ensure enough snow conditions and capture skiers from other ski resorts; and (3) resilient ski resorts, with good conditions to ensure future snow-reliable seasons and outstanding attractiveness, allowing them to offer longer ski seasons than their competitors and potentially attracting skiers from other closed or marginal resorts. Ski resorts included in this last group increase their skier attendance in all climate change scenarios. Although similar studies in the literature foretell a significant reduction of the ski market in the near future, another probable effect outlined in this study is a redefinition of this market due to a redistribution of skiers, from vulnerable ski resorts to more resilient ones.

A critical review of climate change risk for ski tourism

Ski tourism is a multi-billion dollar international market attracting between 300 and 350 million annual skier visits. With its strong reliance on specific climatic conditions, the ski industry is regarded as the tourism market most directly and immediately affected by climate change. A critical review of the 119 publications that have examined the climate change risk of ski tourism in 27 countries is provided. This growing and increasingly diverse literature has projected decreased reliability of slopes dependent on natural snow, increased snowmaking requirements, shortened and more variable ski seasons, a contraction in the number of operating ski areas, altered competitiveness among and within regional ski markets, and attendant implications for ski tourism employment and values of vacation property real estate values. The extent and timing of these consequences depend on the rate of climate change and the types of adaptive responses by skiers as well as ski tourism destinations and their competitors. The need to understanding differential climate risk grows as investors and financial regulators increasingly require climate risk disclosure at the destination and company scale. Key knowledge gaps to better assist ski tourism destinations to adapt to future climate risk are identified.

Error probability in synchronous digital circuits due to power supply noise

This paper presents a probabilistic approach to model the problem of power supply voltage fluctuations. Error probability calculations are shown for some 90-nm technology digital circuits. The analysis here considered gives the timing violation error probability as a new design quality factor in front of conventional techniques that assume the full perfection of the circuit. The evaluation of the error bound can be useful for new design paradigms where retry and self-recovering techniques are being applied to the design of high performance processors. The method here described allows to evaluate the performance of these techniques by means of calculating the expected error probability in terms of power supply distribution quality.

Ground bounce modelling for digital gigascale integrated circuits

In the paper an analytical model for ground bounce noise taking into account the interdependence between switching current and noise voltage is presented. The model shows the discrepancies from general accepted assumption of independence between the two variables. Noise calculations using the independence assumption cause an overestimation of the noise levels. The results are verified through realistic simulations and for different technology nodes

Easing the adoption of agent-based modelling (ABM) in tourism research

Agent-based modelling (ABM) is an emerging approach in tourism research. Despite the natural fit between theories of tourism as a complex, interconnected system, and the generative approach supported in ABM, there has been only limited integration within mainstream tourism research. This research letter reports on a recent gathering of tourism ABM researchers to define the main challenges that face the adoption of ABM in tourism research. These include technical, communications, and novelty issues. In response to these challenges, three potential strategies to ease adoption are outlined: education, awareness, and interdisciplinary teams. These findings are framed as a call for increased attention to the fit of ABM within tourism research, and a framework for negotiating constraints to adoption of this technology.

Fixed origin corner square inspection layout regularity metric

Integrated circuits suffer from serious layout printability issues associated to the lithography manufacturing process. Regular layout designs are emerging as alternative solutions to help reducing these systematic subwavelength lithography variations. However, there is no metric to evaluate and compare the layout regularity of those regular designs and there is no methodology to link layout regularity to the reduction of process variations. In this paper we propose a new layout regularity metric called Fixed Origin Corner Square Inspection (FOCSI). We also provide a methodology using the Monte Carlo analysis to evaluate and understand the impact of regularity on process variability.

Fast time-to-market with via-configurable transistor array regular fabric: A delay-locked loop design case study

Time-to-market is a critical issue for nowadays integrated circuits manufacturers. In this paper the Via-Configurable Transistor Array regular layout fabric (VCTA), which aims to minimize the time-to-market and its associated costs, is studied for a Delay-Locked Loop design (DLL). The comparison with a full custom design demonstrates that VCTA can be used without loss of functionality while accelerating the design time. Layout implementations, in 90nm CMOS process, as well as the delay, energy and jitter electrical simulations are provided.

Power supply noise and logic error probability

Voltage fluctuations caused by parasitic impedances in the power supply rails of modern ICs are a major concern in nowadays ICs. The voltage fluctuations are spread out to the diverse nodes of the internal sections causing two effects: a degradation of performances mainly impacting gate delays and a noisy contamination of the quiescent levels of the logic that drives the node. Both effects are presented together, in this paper, showing than both are a cause of errors in modern and future digital circuits. The paper groups both error mechanisms and shows how the global error rate is related with the voltage deviation and the period of the clock of the digital system.

The differential futures of ski tourism in Ontario (Canada) under climate change: the limits of snowmaking adaptation

The international ski tourism industry is highly vulnerable to inter-annual climate variability and climate change. Accordingly, there is a strong need to advance our understanding of climate risk for this multi-billion tourism market that is so important to mountain regions around the world. This study addressed major limitations in the ski tourism literature, while concurrently supporting priority information needs of ski tourism stakeholders. An improved version of SkiSim 2.0 is applied to all 34 alpine ski areas in southern Ontario (Canada) to examine potential changes in the capacity of this regional marketplace. Model improvements include differential snowmaking capacities of individual ski areas, updated snowmaking decision rules, as well as a new indicator, termed ‘terrain-days’, to estimate changes in system capacity. The results project two fundamentally different futures for this ski tourism marketplace under climate change. If the international community succeeds in achieving the + 2°C Paris Agreement policy goal, then losses in system capacity can be limited to less than 10% in the mid- and late-century. In contrast, a high-end emission scenario (RCP 8.5) would severely disrupt this ski tourism market by mid-century, with system capacity losses between 28% and 73%.