Efficiency assessment of Turkish power plants using data envelopment analysis

The performance of electricity generation plants in Turkey are analyzed and compared. The data set contains inputs from 65 thermal, hydro and wind power plants, owned by private and public sectors. Data envelopment analysis (DEA) is used as the primary mathematical tool. Two efficiency indexes, reflecting operational and investment performance, are defined and pursued. Constant returns to scale, variable returns to scale and assurance region type DEA models are used in the analysis. Scale efficiency is also considered. Performance comparisons include public versus private sector plants, and natural gas versus coal versus oil fired plants. Also, relationships between efficiency scores and various input/output factors are investigated and some interesting trends are identified.     

Natural Majorization of the Quantum Fourier Transformation in Phase-Estimation Algorithms

We prove that majorization relations hold step by step in the Quantum Fourier Transformation (QFT) for phase-estimation algorithms. Our result relies on the fact that states which are mixed by Hadamard operators at any stage of the computation only differ by a phase. This property is a consequence of the structure of the initial state and of the QFT, based on controlled-phase operators and a single action of a Hadamard gate per qubit. The detail of our proof shows that Hadamard gates sort the probability distribution associated to the quantum state, whereas controlled-phase operators carry all the entanglement but are immaterial to majorization. We also prove that majorization in phase-estimation algorithms follows in a most natural way from unitary evolution, unlike its counterpart in Grover's algorithm. PACS: 03.67.-a, 03.67.Lx     

The Effects of Seed Quality and Pipecolic and Djenkolic Acids on Bruchid Beetle Infestation in Water Deficit-Stressed Acacia Trees

Acacia trees in the Negev desert and the Arava valley of Israel are suffering high levels of mortality due to water stress. Additionally, recruitment is negatively affected by bruchid beetles. We hypothesized that water-stressed trees would be less able to produce secondary defense compounds, such as the nonprotein amino acids, pipecolic acid and djenkolic acid, in their seeds to decrease seed herbivory. We further hypothesized that the high seed infestation reported is due to increased fitness of beetles infesting trees that are in a poor physiological state. Contrary to our prediction, pipecolic acid concentration was higher in water-stressed Acacia raddiana trees. We found that infestation rates and beetle fitness were higher in trees in a poor physiological state, despite the higher levels of pipecolic acid in these trees. There was a significant positive correlation between infestation level and the amounts of djenkolic acid in the seeds, indicating that the beetles may have found a means of utilizing djenkolic acid for their own benefit.     

Dynamics of an ultrasonic transducer used for wire bonding

The vibration displacement distributions along a transducer used in ultrasonic wire bonding were measured using a heterodyne interferometer, and many nodes and anti-nodes were found. A mechanical finite element method (FEM) was used to compute the resonant frequencies and vibration mode shapes. The displacement distributions of the dominant 2nd axial mode agreed well with the measured values. Undesirable nonaxial modes, including the higher order flexural and torsional modes, also were excited at frequencies very close to the working frequency (2nd axial mode) of the transducer. Hence, the measured displacements were the resultant of all the allowable modes being excited. However, the excitation of these nonaxial modes were small enough not to affect the formation of consistent and high quality wire bonds. Results of the present study were used to determine a suitable location for installing a piezoelectric sensor to monitor the bond quality.     

Effects of visual and textual information in online product presentations: looking for the best combination in website design

Online product presentation constitutes a key challenge for marketers and designers who want to satisfy consumers’ needs. Visual and textual product information affect recognition and knowledge about the product. This research examines whether the presence (vs absence) of a product image and textual information in a schematic mode (vs paragraph mode) affect users’ recall and perceptions of the quality of the electronic products’ information. The moderating role of user's familiarity with the website and product also may play a role; the evolution of these variables likely will determine trends in e-commerce research. The results show that a schematic display of textual information improves perceptions of information quality. When a picture of the product appears together with textual information, users remember more information and consider it easier to remember if that information appears schematically. However, without a product picture, users allocate more resources to process paragraph information and therefore recall more information and perceive it as easier to recall. The degrees of familiarity also have important directional effects on these relationships.     

A General Stance Stability Test Based on Stratified Morse Theory With Application to Quasi-Static Locomotion Planning

This paper considers the stability of an object supported by several frictionless contacts in a potential field such as gravity. The bodies supporting the object induce a partition of the object's configuration space into strata corresponding to different contact arrangements. Stance stability becomes a geometric problem of determining whether the object's configuration is a local minimum of its potential energy function on the stratified configuration space. We use stratified Morse theory to develop a generic stance stability test that has the following characteristics. For a small number of contacts - less than three in 2D and less than six in 3D - stance stability depends both on surface normals and surface curvature at the contacts. Moreover, lower curvature at the contacts leads to better stability. For a larger number of contacts, stance stability depends only on surface normals at the contacts. The stance stability test is applied to quasi-static locomotion planning in two dimensions. The region of stable center-of-mass positions associated with a k-contact stance is characterized. Then, a quasi-static locomotion scheme for a three-legged robot over a piecewise linear terrain is described. Finally, friction is shown to provide robustness and enhanced stability for the frictionless locomotion plan. A full maneuver simulation illustrates the locomotion scheme.     

The tensor product of two good codes is not necessarily robustly testable

Given two codes R and C, their tensor product $R?C$ consists of all matrices whose rows are codewords of R and whose columns are codewords of C. The product $R?C$ is said to be robust if for every matrix M that is far from $R?C$ it holds that the rows and columns of M are far on average from R and C respectively. Ben-Sasson and Sudan (RSA 28(4), 2006) have asked under which conditions the product $R?C$ is robust.Addressing this question, Paul Valiant (APPROX-RANDOM 2005) constructed two linear codes with constant relative distance whose tensor product is not robust. However, one of those codes has a sub-constant rate. We show that this construction can be modified such that both codes have both constant rate and constant relative distance. We also provide an alternative proof for the non-robustness of the tensor product of those codes, based on the inverse direction of the “rectangle method” that was presented by the second author (ECCC TR07-061). We believe that this proof gives an additional intuition for why this construction works.     

Ground-penetrating radar measurement of crop and surface water content dynamics

Ground-penetrating radar (GPR) with a suspended 1 GHz horn antenna was deployed for measurement of soil water contents and crop canopy properties over bare and electrically terminating surfaces. Surface reflection (SR) and signal propagation times (PT) were used to independently determine dielectric permittivity and water content of soil and canopy. Measured surface reflection coefficients progressively decreased with increasing canopy biomass according to Beer-Lambert type relationships. In contrast, PT measurements remained unaffected by canopy, and hence provided an accurate account of soil water content dynamics. Immediately after canopy removal, SR-based soil water content measurements were in close agreement with PT values. Canopy dielectric properties were inferred from canopy water contents (?_c-CWC) and canopy propagation times (?_c-CPT). Distinct canopy reflections were correlated with key canopy biophysical parameters. The study demonstrates the usefulness of a horn antenna GPR for characterization of vegetation canopy scattering, and for subcanopy water content measurements within a well-defined footprint, thereby offering a potential for calibration and verification of radar data collected from air- and spaceborne platforms.