Thermophysical Properties of Platinum-Copper Alloys

Platinum and copper along with their alloys have been used in a broad range of applications including jewelry, coinage, electrical and electronic devices, and many others. Their thermophysical properties play an important role in casting processes and are required as input data for casting simulation. The focus of this work was to investigate these properties by different methods. Platinum, copper, and four platinum-copper alloys, namely, Pt96Cu04, Pt68Cu32, Pt50Cu50, and Pt25Cu75, were investigated within this work. The melting range and thermal expansion were measured at fem by differential scanning calorimetry and dilatometry, respectively. At TU Graz, wire-shaped samples were investigated by an ohmic pulse heating technique. This technique delivers thermophysical properties of electrically conducting materials far into the liquid phase. These measurements allow the calculation of specific heat capacity and the temperature dependencies of electrical resistivity, enthalpy, and density of these alloys in the solid and liquid phases. Thermal conductivity and thermal diffusivity as a function of temperature are estimated from resistivity data using the Wiedemann?CFranz law at the end of the solid phase and at the beginning of the liquid phase. The results are compared with the available literature values.     

Foreign Ownership Restrictions: A Numerical Approach

In this paper, we analyze the reason behind the use of foreign ownership restrictions on inward Foreign Direct Investment (FDI). We extend the results developed in Karabay (2005) by changing the condition on share distribution in the model. Due to this change, we are able to analyze the political economy aspect of this restrictive policy, i.e., we can study the effect of the host government’s welfare preference on the optimal foreign ownership restriction. Since the analytical solution to the optimal share restriction policy cannot be specified in general, we use a numerical approach based on collocation to approximate the solution to the problem. Within this framework, under certain conditions, it turns out that the rent extraction-efficiency trade-off is sharper the less the host government favors the local firm. We show that not only economic factors but also political factors play an important role in the determination of the foreign ownership restrictions. The views expressed in this paper are those of the authors and are not necessarily reflective of views of the Central Bank of the Republic of Turkey. All errors are our own.     

Complexity of Clausal Constraints Over Chains

We investigate the complexity of the satisfiability problem of constraints over finite totally ordered domains. In our context, a clausal constraint is a disjunction of inequalities of the form x≥d and x≤d. We classify the complexity of constraints based on clausal patterns. A pattern abstracts away from variables and contains only information about the domain elements and the type of inequalities occurring in a constraint. Every finite set of patterns gives rise to a (clausal) constraint satisfaction problem in which all constraints in instances must have an allowed pattern. We prove that every such problem is either polynomially decidable or NP-complete, and give a polynomial-time algorithm for recognizing the tractable cases. Some of these tractable cases are new and have not been previously identified in the literature.     

Decreased emitter sheet resistivity loss in high-eficiency silicon solar cells

State-of-the-art two-dimensional (2D) numerical semiconductor device simulation tools are applied to bifacially contacted silicon solar cells of practical dimensions in order to investigate the 2D effects arising from ohmic voltage drops in cell emitters due to finite front metal grid line spacings. the 2D simulations show that for typical front finger spacings of high-efficiency silicon solar cells the minority carrier flow in the base deviates strongly from the purely linear flow assumed by one-dimensional (1D) theory. Compared to conventional 1D theory, this 2D effect results in reduced emitter sheet resistivity losses, an increased optimum front finger spacing and a reduced impact of finger spacing on cell efficiency. the 2D effects are of particular importance for concentrator solar cells. The 2D simulations presented in this work considerably improve the general understanding of internal device physics of high-efficiency silicon solar cells and reveal the limits of 1D models for the simulation of these devices.     

Full-scale Water Modeling on Flow Field of Continuous Casting Mold

In the continuous casting process of aluminum killed steel grades,nozzle clogging is a common problem.Argon is usually injected into the casting channel through...     

Effect of inter-plies on the short beam shear delamination of steel/composite hybrid laminates

Interlaminar shear test methods (ILS) were implemented to characterize the delamination behavior of asymmetric steel/carbon fiber reinforced plastic (CFRP) hybrids. To improve the delamination behavior thermoplastic inter-plies were inserted between CFRP and steel. Supported by optical strain measurement the maximum shear stress (τ_MAX), the shear stress at interfacial delamination (τ_IF) and the shear stress at large-scale CFRP ply delamination τ_D were evaluated. The significant effect of inter-plies on the adhesion was best reflected by the shear stress value at interfacial delamination. Finite element analysis of the actual shear stress distribution in an asymmetric hybrid sample without inter-ply revealed that the calculated shear strength is just slightly overestimated compared to the standardized evaluation procedure.     

Degradation of photovoltaic backsheets: Comparison of the aging induced changes on module and component level

In reliability testing of components for PV modules an always remaining question is about material (in)compatibilities and synergistic effects and thus, how results of singly tested materials correlate with materials aged within PV modules. Testing of single materials would simplify sample preparation, reduce costs and offer more testing options. Therefore the main objective of this study was to compare the aging behavior of single backsheets with that of backsheets incorporated within PV modules. Four different types of backsheets were chosen, all of them comprising of polyethylene terephthalate (PET) core layers, but differing outer protection layers. Test modules using identical components, varying only in the type of backsheet used were produced and damp heat aged (85°C/85% RH ≤2000 h). The results revealed no influence of the PV module lamination on the thermal characteristics of the polymeric backsheets. Even after DH aging, differences between single and module laminated backsheets were negligible. Degradation effects of PET could be detected for all aged sheets by thermal analysis and were confirmed by tensile tests and rheological measurements. Thus, it can be stated that testing of single PET based backsheets under DH aging conditions is a practicable way to investigate the applicability of a new backsheet. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42093.     

A theoretical analysis of procurement auctions for tertiary control in Germany

As far as energy policy is concerned, the design of the regulatory framework for energy transmission and distribution is a key issue. Consequently, also the embodiment of balancing power markets drives mainly the effectiveness of political implications for the energy sector. Initially, tertiary control in Germany was solely offered by transmission system operators of the respective power control areas and their associated power plant. The recast of the Energy Industry Act of 2005 led in last consequence to a common procurement auction for the supply of tertiary control, which starts on December 1, 2006. Admittedly, the reform has fallen short of expectations so far, first concerning the intensification of market entry of tertiary control providers as well as the desired decline of the price level. Hence, this article examines the effects of the changeover on observable demand charges. In order to identify attributes of the common procurement auction for tertiary control hampering market entry of providers, giving stimuli to collusion and strategic behavior, reducing intensity of competition and encouraging an upswing of prices, we analyze the design under an auction theoretical approach and deduce empirically whether structural components of the auction design have to be touched up again.     

Tuning and implementation variants of discrete-time ADRC

Practical implementations of active disturbance rejection control (ADRC) will almost always take place in discretized form. Since applications may have quite different needs regarding their discrete-time controllers, this article summarizes and extends the available set of ADRC implementations to provide a suitable variant for as many as possible use cases. In doing so, the gap between quasi-continuous and discrete-time controller tuning is closed for applications with low sampling frequencies. The main contribution of this article is the derivation of three different discrete-time implementations of error-based ADRC. It is shown that these are almost one-to-one counterparts of existing output-based implementations, to the point where transfer functions and coefficients can be reused in unaltered form. In this way, error-based implementations become firmly rooted in the established landscape of discrete-time ADRC. Furthermore, it becomes possible to equip error-based variants with windup protection abilities known from output-based ADRC.