Comparative Analysis of Tolerances Allocation in Mechanical Assemblies based on Cost-tolerance Curves

El presente trabajo propone un método para la determinación de los valores de las tolerancias individuales de las piezas que forman un conjunto ensamblado a partir de valores de tolerancias especificados en el conjunto final, optimizando el coste total de fabricación de las piezas individuales a partir de funciones de coste-tolerancia basadas en el proceso de fabricación de cada una de ellas. Para ello se parte de los principales trabajos desarrollados en la línea de asignación de tolerancias y se realiza la propuesta del modelo de trabajo, basado en la optimización de costes a partir de la aplicación del método de los multiplicadores de Lagrange a diversas curvas de coste-tolerancia

Risk Allocation in Toll Highway Concessions in Spain: Lessons from Economic Recession

Spain has a long tradition of encouraging toll highways by granting concessions to private companies. Concessions in Spain have been characterized by a willingness to transfer considerable risk to the private sector. Traffic demand, acquisition of the right-of-way, and financial risk have often been allocated to the private sector. From 1996 to 2011, 16 toll highway concessions, covering a total distance of 835 km, were awarded by the central government of Spain with this approach. Some of those highways started their operations just before the economic recession began. The recession had negative consequences for Spain's economy. The gross domestic product per capita plummeted, and the unemployment rate increased from 9% to 20% of the working population in just 2 years. The recession also had severe consequences for the economic performance of toll highway concessions. Traffic levels declined at a much greater rate than did the gross domestic product. In addition, the conditions imposed by the financial markets on borrowers became much stricter because of the liquidity crisis. This study analyzes the impact that the economic recession ultimately had on the performance of toll highway concessions in Spain and the actions that the government adopted to avoid the bankruptcy of the concessionaires. It was found that the economic recession helped identify some deficiencies in how risk had been allocated in Spain. The measures that both Spain and the European Union are adopting so as to improve risk allocation are discussed.

Managing drought economic effects through insurance schemes based on local water availability.

In many arid or semi-arid Mediterranean regions, agriculture is dependent on irrigation. When hydrological drought phenomena occur, farmers suffer from water shortages, incurring important economic losses. Yet, there is not agricultural insurance available for lack of irrigation water. This work attempts to evaluate hydrological drought risk and its economic impact on crop production in order to provide the basis for the design of drought insurance for irrigated arable crops. With this objective a model that relates water availability with expected yields is developed. Crop water requirements are calculated from evapotranspiration, effective rainfall and soil water balance. FAO?s methodology and AquaCrop software have been used to establish the relationship between water allocations and crop yields. The analysis is applied to the irrigation zone ?Riegos de Bardenas?, which is located in the Ebro river basin, northeast Spain, to the main arable crops in the area. Results show the fair premiums of different hydrological drought insurance products. Whole-farm insurance or irrigation district insurance should be preferable to crop specific insurance due to the drought management strategies used by farmers.

Methodology for assessing regional economic impacts of charging HGVs in Spain: an integrated approach through a random utility based multiregional input-output and a road transportation network model

An integrated approach composed of a random utility-based multiregional input-output model and a road transport network model was developed for evaluating the application of a fee to heavy-goods vehicles (HGVs) in Spain. For this purpose, a distance-based charge scenario (in euros per vehicle kilometer) for HGVs was evaluated for a selected motorway network in Spain. Although the aim of this charging policy was to increase the efficiency of transport, the approach strongly identified direct and indirect impacts on the regional economy. Estimates of the magnitude and extent of indirect effects on aggregated macroeconomic indicators (employment and gross domestic product) are provided. The macroeconomic effects of the charging policy were found to be positive for some regions and negative for other regions.

Temporal task allocation in periodic environments. An approach based on synchronization

In this paper, we study a robot swarm that has to perform task allocation in an environment that features periodic properties. In this environment, tasks appear in different areas following periodic temporal patterns. The swarm has to reallocate its workforce periodically, performing a temporal task allocation that must be synchronized with the environment to be effective. We tackle temporal task allocation using methods and concepts that we borrow from the signal processing literature. In particular, we propose a distributed temporal task allocation algorithm that synchronizes robots of the swarm with the environment and with each other. In this algorithm, robots use only local information and a simple visual communication protocol based on light blinking. Our results show that a robot swarm that uses the proposed temporal task allocation algorithm performs considerably more tasks than a swarm that uses a greedy algorithm.

Resource allocation in GMD and SVD-based MIMO System

Singular-value decomposition (SVD)-based multiple-input multiple output (MIMO) systems, where the whole MIMO channel is decomposed into a number of unequally weighted single-input single-output (SISO) channels, have attracted a lot of attention in the wireless community. The unequal weighting of the SISO channels has led to intensive research on bit- and power allocation even in MIMO channel situation with poor scattering conditions identified as the antennas correlation effect. In this situation, the unequal weighting of the SISO channels becomes even much stronger. In comparison to the SVD-assisted MIMO transmission, geometric mean decomposition (GMD)-based MIMO systems are able to compensate the drawback of weighted SISO channels when using SVD, where the decomposition result is nearly independent of the antennas correlation effect. The remaining interferences after the GMD-based signal processing can be easily removed by using dirty paper precoding as demonstrated in this work. Our results show that GMD-based MIMO transmission has the potential to significantly simplify the bit and power loading processes and outperforms the SVD-based MIMO transmission as long as the same QAM-constellation size is used on all equally-weighted SISO channels.

Economic Impacts of Rules-based vs Risk-based Cybersecurity Regulations in Critical Infrastructure Providers (Bulk Electricity Providers)

Economics of Cybersecurity Part 2. SPSI-2015-01-0024.

A qualitative exploration of the impact of the economic recession in Spain on working, living and health conditions: reflections based on immigrant workers' experiences

Background: This study aimed to analyse how immigrant workers in Spain experienced changes in their working and employment conditions brought about Spain's economic recession and the impact of these changes on their living conditions and health status. Method: We conducted a grounded theory study. Data were obtained through six focus group discussions with immigrant workers (n = 44) from Colombia, Ecuador and Morocco, and two individual interviews with key informants from Romania living in Spain, selected by theoretical sample. Results: Three categories related to the crisis emerged – previous labour experiences, employment consequences and individual consequences – that show how immigrant workers in Spain (i) understand the change in employment and working conditions conditioned by their experiences in the period prior to the crisis, and (ii) experienced the deterioration in their quality of life and health as consequences of the worsening of employment and working conditions during times of economic recession. Conclusion: The negative impact of the financial crisis on immigrant workers may increase their social vulnerability, potentially leading to the failure of their migratory project and a return to their home countries. Policy makers should take measures to minimize the negative impact of economic crisis on the occupational health of migrant workers in order to strengthen social protection and promote health and well-being.

The fiscal compact - Europe's "hard core" based on German economic conditions. OSW Commentary No. 71, 2012-03-07

On 2 March, the leaders of 25 EU member states signed the Treaty on stability, coordination and governance in the economic and monetary union. It will introduce new fiscal constraints and officially vest new competences in the eurozone countries. Thus, their right to coordinate economic policy among them will be sanctioned. So far, the Lisbon Treaty has only provided for organisation of informal Eurogroup meetings, to be attended by representatives of the European Commission. The principles introduced by the compact, if the eurozone countries are really determined to observe its provisions, will create a new way of managing the single currency. Within the next few years, the most indebted countries will have to carry out radical reforms to boost their competitiveness and adjust it to German standards. During this period the Federal Republic of Germany will most probably decide to offer higher loan guarantees to relieve these countries’ budgets. The compact’s political consequences are also of great significance, especially considering how the treaty was finalised. The eurozone states have in fact accepted that the direction for changes will be devised by France and Germany, and the role of European institutions such as the Commission or the Parliament may weaken. From the perspective of eurozone candidate countries, the introduction of the fiscal compact means expanding the scope of conditions they must meet to become members of the single currency area. In the future, a country, in order to adopt the single currency, will have to meet the structural deficit criterion, and also most probably carry out economic reforms such as unifying its fiscal system. These goals will be achieved across the eurozone gradually, in the subsequent stages of the economic governance reform.

The Economics of EU Railway Reform. Bruges European Economic Policy (BEEP) Briefing 8/2004

The EU began railway reform in earnest around the turn of the century. Two ‘railway packages’ have meanwhile been adopted amounting to a series of directives and a third package has been proposed. A range of complementary initiatives has been undertaken or is underway. This BEEP Briefing inspects the main economic aspects of EU rail reform. After highlighting the dramatic loss of market share of rail since the 1960s, the case for reform is argued to rest on three arguments: the need for greater competitiveness of rail, promoting the (market driven) diversion of road haulage to rail as a step towards sustainable mobility in Europe, and an end to the disproportional claims on public budgets of Member States. The core of the paper deals respectively with market failures in rail and in the internal market for rail services; the complex economic issues underlying vertical separation (unbundling) and pricing options; and the methods, potential and problems of introducing competition in rail freight and in passenger services. Market failures in the rail sector are several (natural monopoly, economies of density, safety and asymmetries of information), exacerbated by no less than 7 technical and legal barriers precluding the practical operation of an internal rail market. The EU choice to opt for vertical unbundling (with benefits similar in nature as in other network industries e.g. preventing opaque cross-subsidisation and greater cost revelation) risks the emergence of considerable coordination costs. The adoption of marginal cost pricing is problematic on economic grounds (drawbacks include arbitrary cost allocation rules in the presence of large economies of scope and relatively large common costs; a non-optimal incentive system, holding back the growth of freight services; possibly anti-competitive effects of two-part tariffs). Without further detailed harmonisation, it may also lead to many different systems in Member States, causing even greater distortions. Insofar as freight could develop into a competitive market, a combination of Ramsey pricing (given the incentive for service providers to keep market share) and price ceilings based on stand-alone costs might be superior in terms of competition, market growth and regulatory oversight. The incipient cooperative approach for path coordination and allocation is welcome but likely to be seriously insufficient. The arguments to introduce competition, notably in freight, are valuable and many e.g. optimal cross-border services, quality differentiation as well as general quality improvement, larger scale for cost recovery and a decrease of rent seeking. Nevertheless, it is not correct to argue for the introduction of competition in rail tout court. It depends on the size of the market and on removing a host of barriers; it requires careful PSO definition and costing; also, coordination failures ought to be pre-empted. On the other hand, reform and competition cannot and should not be assessed in a static perspective. Conduct and cost structures will change with reform. Infrastructure and investment in technology are known to generate enormous potential for cost savings, especially when coupled with the EU interoperability programme. All this dynamism may well help to induce entry and further enlarge the (net) welfare gains from EU railway reform. The paper ends with a few pointers for the way forward in EU rail reform.