Method for improving ladder bulk acoustic wave filters rejection

This paper address design guidelines for improving the rejection of ladder bulk acoustic wave filters. An overview of the bulk acoustic wave filters technology enables to outcome the principal features of ladder filters. The lack of out-of-band rejection is currently an important weakness of this topology. The design technique presented enables to improve bulk acoustic wave ladder filters rejection by using their input/output bonding wires. Finally, the technique is used for design and fabrication of a bulk acoustic wave ladder filter for application in W-CDMA reception (2.11–2.17 GHz) front-ends. The filter measurement results show a significant improvement on the filter rejection at the transmission band (from ?19 to 34 dB) and on the return loss (from ?10 to ?16 dB) without considerable modification of filter insertion loss and selectivity.     

Transformer Fleet Optimal Maintenance with Risk Considerations

Abstract

This paper aims at proposing an optimization model for high voltage transformers’ maintenance scheduling to minimize operational cost and risk. The focus of the paper is on the transformer fleet management, and not on a single transformer maintenance procedure or the evaluation of a single transformer failure risk. The proposed methodology takes as inputs the importance (e.g., based on the expected energy not supplied) and failure risk of each transformer (e.g., based on on-line Dissolved Gas Analysis), and the maintenance cost for each transformer. It also considers the main practical constraints in field interventions. As output, the proposed methodology provides the best timing for the maintenance of each transformer from the fleet of interest. The problem has been modeled as mixed-integer linear programming. Eleven months of real data from the Brazilian transmission system are used for setting up the recent history of outages. The following year data are employed to test the effectiveness of the optimization model. The output of the proposed fleet maintenance scheduling tool is the optimum viable intervention calendar for a power transformer fleet within a 52-week horizon. This proposal represents an innovative and robust solution, which can support the operational planning experts’ decision-making process.     

Nuclear plant’s virtual simulation for on-line radioactive environment monitoring and dose assessment for personnel

This paper reports the use of nuclear plant’s simulation for online dose rate monitoring and dose assessment for personnel, using virtual reality technology. The platform used for virtual simulation was adapted from a low cost game engine, taking advantage of all its image rendering capabilities, as well as the physics for movement and collision, and networking capabilities for multi-user interactive navigation. A real nuclear plant was virtually modeled and simulated, so that a number of users can navigate simultaneously in this virtual environment in first or third person view, each one receiving visual information about both the radiation dose rate in each actual position, and the radiation dose received. Currently, this research and development activity has been extended to consider also on-line measurements collected from radiation monitors installed in the real plant that feed the simulation platform with dose rate data, through a TCP/IP network. Results are shown and commented, and other improvements are discussed, as the execution of a more detailed dose rate mapping campaign.     

Gas Permeability of Porous Plasma-Sprayed Coatings

For different applications, such as solid oxide fuel cells, there is an interest in understanding the relationship between the microstructure and the gas permeability of plasma-sprayed coatings. Nevertheless, plasma spraying processes allow to elaborate coatings with singular microstructures, depending strongly on the initial material and plasma operating conditions. And so, the evolution of permeability is not directly linked to the porosity. In this work, coatings were manufactured using different initial feedstock and spray parameters to obtain various microporous structures. Measurements of their permeation with the pressure drop method and their open porosity just as the observation of the morphology and the structure by optical microscopy were achieved. The different data show that the evolution of the gas permeability with the open porosity follows the Kozeny-Carman equation. This result correlated with the microstructural observation highlights the relationship between the permeability and the physical properties of porous plasma-sprayed layers.     

Many task computing for orthologous genes identification in protozoan genomes using Hydra

One of the main advantages of using a scientific workflow management system (SWfMS) is to orchestrate data flows among scientific activities and register provenance of the whole workflow execution. Nevertheless, the execution control of distributed activities in high performance computing environments by SWfMS presents challenges such as steering control and provenance gathering. Such challenges may become a complex task to be accomplished in bioinformatics experiments, particularly in Many Task Computing scenarios. This paper presents a data parallelism solution for a bioinformatics experiment supported by Hydra, a middleware that bridges SWfMS and high performance computing to enable workflow parallelization with provenance gathering. Hydra Many Task Computing parallelization strategies can be registered and reused. Using Hydra, provenance may also be uniformly gathered. We have evaluated Hydra using an Orthologous Gene Identification workflow. Experimental results show that a systematic approach for distributing parallel activities is viable, sparing scientist time and diminishing operational errors, with the additional benefits of distributed provenance support. Copyright © 2011 John Wiley & Sons, Ltd.     

A bibliography of non-deterministic lot-sizing models

Non-deterministic lot-sizing models are considered which serve for an explicit determination of lot sizes in an uncertain environment. Taxonomy components for such models are suggested and a bibliography structured according to these components is presented. The taxonomy components are numeric characteristics of a lot-sizing problem, names of uncertain parameters and names of approaches to model the uncertainty. The bibliography covers more than 300 publications since the year 2000.     

On the quantization of the electromagnetic field in conducting media

In this work we investigate the quantization of electromagnetic waves propagating through homogeneous conducting linear media with no charge density. We use Coulomb's gauge to reduce the problem to that of a time-dependent harmonic oscillator, which is described by the Caldirola–Kanai Hamiltonian. Furthermore, we obtain the corresponding exact wave functions with the help of quadratic invariants and of the dynamic invariant method. These wave functions are written in terms of a particular solution of the Milne–Pinney equation. We also construct coherent and squeezed states for the quantized electromagnetic waves and evaluate the quantum fluctuations in coordinates and momentum as well as the uncertainty product for each mode of the electromagnetic field.     

Cash flow risk in dual-channel supply chain

This paper focuses on multi-period cash flow risk which is measured by the SD in dual-channel supply chain. The manufacturer offers a consignment contract to the retailer, exposing cash flow risk due to the payment delay. We analyze cash inflows, outflows, and netflows of each member in dual-channel supply chain. We also examine different influencing factors on the preference of cash flows in dual-channel supply chain and then provide some managerial implications to deal with cash flow risk.