2,805 research outputs found
Transmission needs across a fully renewable European power system
The residual load and excess power generation of 27 European countries with a
100% penetration of variable renewable energy sources are explored in order to
quantify the benefit of power transmission between countries. Estimates are
based on extensive weather data, which allows for modelling of hourly
mismatches between the demand and renewable generation from wind and solar
photovoltaics. For separated countries, balancing is required to cover around
24% of the total annual energy consumption. This number can be reduced down to
15% once all countries are networked together with uncon- strained
interconnectors. The reduction represents the maximum possible benefit of
transmission for the countries. The total Net Transfer Capacity of the
unconstrained interconnectors is roughly twelve times larger than current
values. However, constrained interconnector capacities six times larger than
the current values are found to provide 97% of the maximum possible benefit of
cooperation. This motivates a detailed investigation of several constrained
transmission capacity layouts to determine the export and import capabilities
of countries participating in a fully renewable European electricity system
Current driven switching of magnetic layers
The switching of magnetic layers is studied under the action of a spin
current in a ferromagnetic metal/non-magnetic metal/ferromagnetic metal spin
valve. We find that the main contribution to the switching comes from the
non-equilibrium exchange interaction between the ferromagnetic layers. This
interaction defines the magnetic configuration of the layers with minimum
energy and establishes the threshold for a critical switching current.
Depending on the direction of the critical current, the interaction changes
sign and a given magnetic configuration becomes unstable. To model the time
dependence of the switching process, we derive a set of coupled Landau-Lifshitz
equations for the ferromagnetic layers. Higher order terms in the
non-equilibrium exchange coupling allow the system to evolve to its
steady-state configuration.Comment: 8 pages, 2 figure. Submitted to Phys. Rev.
Mobilizing the Temporary Organization: The Governance Roles of Selection and Pricing
Many marketing transactions between buyers and suppliers involve short-term collaborations or so-called temporary organizations. Such organizations have considerable value-creation potential but also face challenges, as evidenced by their mixed performance records. One particular challenge involves relationship governance, and in this respect, temporary organizations represent a conundrum: On the one hand, they pose significant governance problems due to the need to manage numerous independent specialists under time constraints. On the other hand, temporary organizations lack the inherent governance properties of other organizational forms such as permanent organizations. The authors conduct an empirical study of 429 business-to-business construction projects designed to answer two specific questions: First, how are particular selection and pricing strategies deployed in response to monitoring and coordination problems? Second, does the joint alignment between the two mechanisms and their respective attributes help mitigate cost overruns? The authors follow a formal hypothesis test with a series of in-depth interviews to explore and to gain insight into the validity of the key constructs, explanatory mechanisms, and outcomes. Managerially, the authors answer the long-standing question of how to mobilize a temporary organization. Theoretically, they develop an augmented “discriminating alignment” heuristic for relationship management involving multiple governance mechanisms and attributes.acceptedVersio
Tobacco Industry Attempts to Influence and Use the German Government to Undermine the WHO Framework Convention on Tobacco Control
Background Germany has been identified as one of a few high-income countries that opposed a strong Framework Convention on Tobacco Control (FCTC), the WHO's first global public health treaty. This paper examines whether the tobacco industry had influenced the German position on the FCTC.
Methods Analysis of previously confidential tobacco industry documents.
Results The tobacco industry has identified Germany as a key target within its global strategy against the FCTC. Building on an already supportive base, the industry appears to have successfully lobbied the German government, influencing Germany's position and argumentation on key aspects of the FCTC. It then used Germany in its efforts to weaken the FCTC. The evidence suggests that the industry enjoyed success in undermining the Federal Health Ministry's position and using Germany to limit the European Union negotiating mandate. The tactics used by the tobacco industry included the creation of controversy between the financial, trade and other ministries on one side and the health ministry on the other side, the use of business associations and other front groups to lobby on the industry's behalf and securing industry access to the FCTC negotiations via the International Standardization Organization.
Conclusion The evidence suggests that Germany played a major role in the tobacco industry's efforts to undermine the FCTC. Germany's position consistently served to protect industry interests and was used to influence and constrain other countries. Germany thus contributed significantly to attempts to weaken an international treaty and, in doing so, failed in its responsibility to advance global health
Convolutional sparse coding for high dynamic range imaging
Current HDR acquisition techniques are based on either (i) fusing multibracketed, low dynamic range (LDR) images, (ii) modifying existing hardware and capturing different exposures simultaneously with multiple sensors, or (iii) reconstructing a single image with spatially-varying pixel exposures. In this paper, we propose a novel algorithm to recover high-quality HDRI images from a single, coded exposure. The proposed reconstruction method builds on recently-introduced ideas of convolutional sparse coding (CSC); this paper demonstrates how to make CSC practical for HDR imaging. We demonstrate that the proposed algorithm achieves higher-quality reconstructions than alternative methods, we evaluate optical coding schemes, analyze algorithmic parameters, and build a prototype coded HDR camera that demonstrates the utility of convolutional sparse HDRI coding with a custom hardware platform
Electromagnetic vertex function of the pion at T > 0
The matrix element of the electromagnetic current between pion states is
calculated in quenched lattice QCD at a temperature of . The
nonperturbatively improved Sheikholeslami-Wohlert action is used together with
the corresponding improved vector current. The electromagnetic
vertex function is extracted for pion masses down to and
momentum transfers .Comment: 17 pages, 8 figure
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