Medium-term Developments Research Articles

Numerical and experimental evaluation of the passive pre-chamber concept for future CNG SI engines

The third decade of the 21st century is set to be one of the most relevant in terms of the transition of methods and forms of using different energy sources, with short and medium-term developments on the road to decarbonization. One of the most widely accepted measures on this path is the reduction of CO2 emissions from internal combustion engines, which is why different concepts are being studied in order to optimize combustion. Furthermore, this research focuses on developing a suitable Spark-Ignition (SI) engine configuration integrating the passive pre-chamber ignition concept (TJI), together with a high compression ratio and the use of the Miller cycle, in order to exploit the benefits of using Compressed Natural Gas (CNG) as fuel. Thus, the novelty of this investigation is the detailed evaluation of the aforementioned SI engine architecture by state-of-the-art CFD simulations and a broad experimental campaign, to understand the advantages of the combined technologies against a conventional SI engine operating with gasoline. The pre-chamber technology is able to overcome the issues associated with the lower laminar flame speeds of CNG, and the reduction of turbulence caused by prematurely closing the intake valve with the Miller cycle. The experimental results showed that the new engine definition achieved higher levels of indicated efficiency compared to the baseline engine (around a 3% increase at high load/speed conditions). Moreover, the addition of EGR allows to further improve the engine performance, extending the load limit in the low-end torque region of the engine map. Finally, a full dynamic 1D model of a current passenger car vehicle was developed to perform transient driving cycle simulations, showing a reduction of 15% in fuel consumption and 25% in CO2 emissions for the new engine definition compared to the baseline engine.

A life Expectancy-Period-Cohort model to project private car fleet and traffic applied to France

In most industrialized countries, after decades of gradually slowed growth, car traffic stagnated in the 2000s. This phenomenon has been attributed not only to conventional economic factors (stagnation of incomes, upward volatility in fuel prices) and to re-urbanization linked to metropolisation, but also to demographic factors (ageing of the population, longer life cycle stages leading in particular to delay the passage of the driving license in the younger generations). The economic recovery, albeit rather slow, and a significant drop in the price of oil in 2014 favored a certain revival of traffic growth in several countries (U.S.A., Germany, France, ...); but what about the structural factors and how to predict medium-term developments? We have already dealt with these questions via Age-Period-Cohort models, and more often Age-Cohort (AC). In view of the over-determination generated by the mechanical link between these three factors, we propose a Life Expectancy-Period-Cohort model (EPC); indeed, by replacing age by life expectancy at this age and at each date, the model can be directly estimated keeping the three components, while making this approach more consistent with the extension of life cycle stages (longer studies, women having their children in their thirties, postponement of retirement age, ...). Period effects are specified by introducing the income of the household and a fuel price index as explanatory variables. The results are compared with those of various previous models.The scope is the adult population (i.e., of driving age), considering three phases for automobile behavior:- to pass the driver’s license,- to be the main user of a vehicle,- to ride (annual mileage) or frequency of use of the vehicle.Once the model is estimated on the data of the Parc-Auto Kantar-SOFRES 1994-2016 panel survey, an example of medium-term (horizon 2030) projection of the annual mileage is presented, being aware that in the long term the technical innovations (autonomous vehicle, electric and hybrid engines) and organizational evolution (car sharing, carpooling, ...) are likely to fundamentally change the conditions of use of the car.

Artificial Intelligence's Societal Impacts, Governance, and Ethics

AI’s societal impacts and governance challenges carry high stakes but are deeply uncertain, due to uncertainties in both the characteristics and capabilities of the technologies and in how they will be developed, deployed, and used in social and political context. We provide an introduction and synthesis of discussions at the 2019 Summer Institute on AI and Society, an intense interdisciplinary exploration of these issues. The summer institute used an experimental model to promote informed discussions among a diverse international group of researchers, professionals, and students: one day of focused briefings, followed by two days of collaborative group work on projects proposed and selected by participants via a real-time decision process. The workgroups that emerged from this process examined a wide range of questions: embedded values in automated mobility systems; the concept of meaningful human control in complex human-machine decision systems; the prospect of AI systems replacing policy analysis in government decision-making; how AI challenges and changes conventional understandings of agency; the feasibility and requirements for AI to drive large-scale societal progress; and two distinct perspectives on the multiple sets of proposed AI ethical principles and attempts to make these operational: one a practical attempt to develop and specify such an operationalization, and one a critique of an existing operationalization recently proposed by an EU expert group. Workgroup discussions offered new insights on the risks posed to corollary or implicit values in present institutions or systems that may be inherent in automating or codifying decisions; the frequency with which seemingly prosaic matters of AI system design directly implicate deep political and moral issues; the value of a dialectical or adversarial approach to assessing impacts of AI systems or governance efforts; and the acute need for methods to assess and manage medium-term AI developments and impacts.

A regionális politika helyzete és perspektívái

A regionális politika több másik területtel fejlődik kölcsönhatásban, ennek fényében a jelen írásnak is multidimenzionális elemzés a célja. Ez azonosítható a politika jelenlegi helyzetének elemzésével, valamint közép- és hosszú távú perspektíváival. Ennek megfelelően a regionális politika rövid áttekintését a regionális politika jelen idejű eredményességének, illetve problémáinak bemutatása követi. A középtávú elemzés azt vizsgálja, hogy az új költségvetési időszak, a 2014–2020-as többéves pénzügyi keret hogyan kíván válaszolni a regionális politika terén felmerülő kérdésekre. E ponton az elemzés fókuszában a lisszaboni szerződéssel bevezetett intézményi újítások állnak, és kritikailag értelmezem a többéves pénzügyi keretet mint a minden félnek előnyös szerződést. Végül egy hosszú távú kitekintés keretében a dolgozat arra tesz kísérletet, hogy bemutassa az Európai Unió potenciális bővítésének várható hatását a regionális politikára.

Sensitivity Analysis of a Land-Use Change Model with and without Agents to Assess Land Abandonment and Long-Term Re-Forestation in a Swiss Mountain Region

Land abandonment and the subsequent re-forestation are important drivers behind the loss of ecosystem services in mountain regions. Agent-based models can help to identify global change impacts on farmland abandonment and can test policy and management options to counteract this development. Realigning the representation of human decision making with time scales of ecological processes such as reforestation presents a major challenge in this context. Models either focus on the agent-specific behavior anchored in the current generation of farmers at the expense of representing longer scale environmental processes or they emphasize the simulation of long-term economic and forest developments where representation of human behavior is simplified in time and space. In this context, we compare the representation of individual and aggregated decision-making in the same model structure and by doing so address some implications of choosing short or long term time horizons in land-use modeling. Based on survey data, we integrate dynamic agents into a comparative static economic sector supply model in a Swiss mountain region. The results from an extensive sensitivity analysis show that this agent-based land-use change model can reproduce observed data correctly and that both model versions are sensitive to the same model parameters. In particular, in both models the specification of opportunity costs determines the extent of production activities and land-use changes by restricting the output space. Our results point out that the agent-based model can capture short and medium term developments in land abandonment better than the aggregated version without losing its sensitivity to important socio-economic drivers. For comparative static approaches, extensive sensitivity analysis with respect to opportunity costs, i.e., the measure of benefits forgone due to alternative uses of labor is essential for the assessment of the impact of climate change on land abandonment and re-forestation in mountain regions.

A portfolio balance approach to Euro-area money demand in a time-varying environment

As part of its monetary policy strategy, the European Central Bank has formulated a reference value for M3 growth. A pre-requisite for the use of a reference value for M3 growth is the existence of a stable demand function for that aggregate. However, a large empirical literature has emerged showing that, beginning in 2001, essentially all euro area M3 demand functions have exhibited instability. This paper argues that a proper understanding of the determination of money requires a portfolio analysis where the demand for broad money is seen as just one element in the wealth portfolio. Under this framework, wealth is the variable that constitutes the total budget constraint on the holdings of assets, including money, and changes in equity prices are a key transmission channel of monetary policy. Understanding money behaviour thus requires good data on euro area wealth which at present do not exist. Our basic premise is that there is a stable demand-for-money function but that the models that have been used until now to estimate euro area money-demand are not well-specified because they do not include a measure of wealth. Using two empirical methodologies - - a co-integrated vector equilibrium correction (VEC) approach and a time-varying coefficient (TVC) approach - - we find that a demand-for-money function that includes wealth is stable. The upshot of our findings is that M3 behaviour continues to provide useful information about medium-term developments on inflation.

CRYSTALLINE SILICON BASED PHOTOVOLTAICS: TECHNOLOGY AND MARKET TRENDS

An overview is given concerning industrial technologies, IMECS's advanced pilot line crystalline silicon solar cell technologies and medium term developments for industrial crystalline silicon terrestrial solar cell fabrication. Also IMEC's work on thin film crystalline silicon solar cells is shortly presented, all of this taking into account the existing market and technology trends.

Advanced cost-effective crystalline silicon solar cell technologies

An overview is given concerning current industrial technologies, near future improvements and medium-term developments in the field of industrially viable crystalline silicon terrestrial solar cell fabrication (without concentration).

Advanced manufacturing concepts for crystalline silicon solar cells

An overview is given concerning current industrial technologies, near future improvements and medium term developments in the field of industrially implementable crystalline silicon solar cell fabrication. The paper proves that considerable improvements are still possible, both in efficiency and in production cost. The paper also proves that a lot of effort is being put worldwide on thinner substrates and on thin-film crystalline silicon cells deposited on cheap carriers, in order to save in substrate cost and in order to gain more independence from availability problems of silicon feedback.

Milk production

This paper outlines some of the factors likely to influence the development of the United Kingdom dairy industry over the next decade. It considers the role of non‐European Community countries in European milk supply and utilization, the impact of changing agricultural policies and the strategies available to dairy farmers to respond to the challenges that lie ahead. It is concluded that while Eastern European countries may have long term importance as sources of low cost milk production the influences of changing agricultural policy and marketing frameworks within the EC will have a more immediate and more significant impact on UK dairy farmers. It is envisaged that medium term developments in the UK will include an increased variety in the linkages between producers and retailers and producers and manufacturers; some resurgence in farm‐based manufacturing; increased emphasis on milk compositional quality and manufacturing characteristics; continued pressure to reduce unit costs of farm production; and a movement towards lower input, less intensive systems of production.

Postoperative course after suction lipectomy ?immediate, medium-term and long-term outcomes

The final result of suction lipectomy depends in part on the immediate and medium-term developments. The two factors, skin retractility and surface unevenness which exert an important influence on the results, are analyzed in an attempt to determine the relative parts played by the surgical procedure and by the patient's characteristics. The outcome of suction lipectomy is studied, and the criteria used to select suitable patients are discussed. The events that may occur postoperatively are examined in order to see how they may affect long-term results. The following points are analyzed: (1) The immediate outcome, including the problems of ecchymosis and surface unevenness, and the influence of the skin's retractile property. (2) The problem of secondary bulges; and (3) the long-term developments.

Building energy simulation: The state-of-the-art

This paper is concerned with building energy simulation and the prospects for the delivery of valid, easy to use models to the design profession. The issues underlying the use in practice of Computer-Aided Building Design (CABD) systems are described and it is shown that many complementary developments have yet to mature and conflate before the true power of CABD can be delivered to the design profession. The paper also describes some medium and long term developments, including a knowledge based ‘front-end’ for simulation and the notion of an advanced machine environment for the construction and maintenance of future models.

The challenges facing Latin America in the world today

In this article the author analyses various long- and medium-term developments in the world economy and in the sphere of international economics and politics and explores their impact on Latín America. He then goes on to consider the regional scenario and, in particular, the current economic crisis, with special attention being devoted to the efforts made by Latin America to improve its present position.

Chapter III. The British Economy Since 1979

Five years has been the average, and indeed the typical, duration of a full cycle in the British economy since the war. For that reason it has been taken as a convenient time span when considering medium-term developments such as the trend rate of growth of output or productive potential. If we now look back five years from 1987 the annual growth rate averages about 3½ per cent, suggesting a marked improvement in trend since the 1970s. This may be the correct conclusion to draw, but it cannot be accepted uncritically since the pattern of five-year cycles seems to have changed.

Medium-Term Planning in UK Nationalised Industries: An Enquiry

There is now, of course, no official medium-term National Plan. The Government in recent years has published very little about possible medium-term developments. In the Public Expenditure White Paper, from December 1972 up to February 1976, there was a single table outlining the possible evolution of the economy over the four-year period which the public expenditure forward estimates cover. In the last two public expenditure white papers, even this single table has been dropped. In the latest paper there is the highly tentative suggestion that gross domestic product might rise at 3½ per cent a year up to 1979-80—but nothing is said about the macro-economic assumptions for later years. There is now no table showing the distribution of resources which might accompany this growth-rate—merely a text reference which says that ‘a rise in the proportion of national income devoted to industrial investment is essential…’

Current and medium term developments in switching

The current and medium term developments in switching are characterized by the extensive use of stored program control, digital switching and common channel signalling. In implementation terms, integrated circuit silicon semiconductor technology dominates. From the user’s viewpoint, these developments should result in large reductions in equipment size and procurement times, improved operational, maintenance and subscriber facilities, and an enhanced ability to cope with the evolving needs of both public and private telecommunication networks.