Stationarity Changes in Long-Run Fossil Resource Prices: Evidence from Persistence Break Testing

This paper considers the question of whether changes in persistence have occurred during the long-run evolution of U.S. prices of the non-renewable energy resources crude oil, natural gas and bituminous coal. Our main contribution is to allow for a structural break when testing for a break in persistence, thus disentangling the effect of a deterministic break from that of a stochastic break and advancing the existing literature on the persistence properties of non-renewable resource prices. The results clearly demonstrate the importance of specifying a structural break when testing for breaks in persistence, whereas our findings are robust to the exact date of the structural break. Our analysis yields that coal and natural gas prices are trend stationary throughout their evolution, while oil prices exhibit a break in persistence during the 1970s. The findings suggest that especially the coal market has remained fundamentals-driven, whereas for the oil market exogenous shocks have become dominant. Thus, our results are consequential for the treatment of energy resource prices in both causal analysis and forecasting.non-renewable resource prices, primary energy, persistence, structural breaks

An Empirical Analysis of the Currency Hedging Behavior of North German SMEs

In a globalized world, companies are able to sell their products or services abroad or purchase them abroad. This generates advantages due to the expansion of the business area creating a broader market but comes along with currency risks. This paper examines which factors influence German SMEs' willingness to conduct foreign business, respectively to do transactions in foreign currencies. An empirical study researches how the currency risk in North German SMEs is valued and assessed. The analysis further identifies the differences in the use of foreign currencies of rural and urban SMEs and examines the reasons for the use of foreign currencies and currency management which lead to the use of currency hedging. With a sample size of 73 SMEs the study aims for a better understanding of the foreign activities of German SMEs and investigates the approach to the currency risk management for a better understanding of their needs. In general, the paper shows that the larger a company is, the more likely is the use of a currency management. A comparison of rural and urban SMEs in Northern Germany reveals, that urban ones are larger and therefore more likely to use currency hedging. Based on the research, the paper provides recommendations for SMEs with foreign sales.O

Fitted Q-iteration by advantage weighted regression

Recently, fitted Q-iteration (FQI) based methods have become more popular due to their increased sample efficiency, a more stable learning process and the higher quality of the resulting policy. However, these methods remain hard to use for continuous action spaces which frequently occur in real-world tasks, e.g., in robotics and other technical applications. The greedy action selection commonly used for the policy improvement step is particularly problematic as it is expensive for continuous actions, can cause an unstable learning process, introduces an optimization bias and results in highly non-smooth policies unsuitable for real-world systems. In this paper, we show that by using a soft-greedy action selection the policy improvement step used in FQI can be simplified to an inexpensive advantage weighted regression. With this result, we are able to derive a new, computationally efficient FQI algorithm which can even deal with high dimensional action spaces

Using microcomputers for lighting appliance control using a DALI bus

Article concerns the DALI bus theoretical and practical aspects. The DALI bus is a modern technology developed especially for illumination systems control. Authors are outlining communication basic principles related to the physical layer and going up to more complex data transactions among particular devices. The article main topic is aimed at two device models development based on microcontroller and exploiting that technology. The first of those two devices is a DALI slave unit enabling the light source or multi switch with light indication components control via DALI bus. The second device measures the ambient illumination intensity and it also detects errors in the load.Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; European Regional Development Fund under the project CEBIA-Tech [CZ.1.05/2.1.00/03.0089

Formation of long-lived, scarlike modes near avoided resonance crossings in optical microcavities

We study the formation of long-lived states near avoided resonance crossings in open systems. For three different optical microcavities (rectangle, ellipse, and semi-stadium) we provide numerical evidence that these states are localized along periodic rays, resembling scarred states in closed systems. Our results shed light on the morphology of long-lived states in open mesoscopic systems.Comment: 4 pages, 5 figures (in reduced quality), to appear in Phys. Rev. Let

Human Factors: Spanning the Gap between OM & HRM

Purpose: This paper examines the claim that the application of human factors (HF) knowledge can improve both human well-being and operations system performance. Methodology: A systematic review was conducted using a general and two specialist databases to identify empirical studies addressing both human effects and operations system effects in examining manufacturing operations system design aspects. Findings: We found 45 empirical studies addressing both the human effects and system effects of operations system (re)design. Of those studies providing clear directional effects, 95% showed a convergence between human effects and system effects (+,+ or -,-), 5% showed a divergence of human and system effects (+,- or -,+). System effects included quality, productivity, implementation performance of new technologies, and also more ‘intangible’ effects in terms of improved communication and co-operation. Human effects included employee health, attitudes, physical workload, and ‘quality of working life’. Research limitations/im

Hierarchical relative entropy policy search

Many real-world problems are inherently hierarchically structured. The use of this structure in an agent’s policy may well be the key to improved scalability and higher performance. However, such hierarchical structures cannot be exploited by current policy search algorithms. We will concentrate on a basic, but highly relevant hierarchy — the ‘mixed option’ policy. Here, a gating network first decides which of the options to execute and, subsequently, the option-policy determines the action. In this paper, we reformulate learning a hierarchical policy as a latent variable estimation problem and subsequently extend the Relative Entropy Policy Search (REPS) to the latent variable case. We show that our Hierarchical REPS can learn versatile solutions while also showing an increased performance in terms of learning speed and quality of the found policy in comparison to the nonhierarchical approach