Properties and Performance of Cation-Doped Ceria Electrolyte Materials in Solid Oxide Fuel Cell Applications

Cation-doped CeO₂ electrolyte has been evaluated in single-cell and short-stack tests in solid oxide fuel cell environments and applications. These results, along with conductivity measurements, indicate that an ionic transference number of ∼0.75 can be expected at 800°C. Single cells have shown a power density >350 mW/cm². Multicell stacks have demonstrated a peak performance of >100 mW/cm² at 700°C using metallic separators.     

Single-channel speech separation using empirical mode decomposition and multi pitch information with estimation of number of speakers

Speech separation is an essential part of any voice recognition system like speaker recognition, speech recognition and hearing aids etc. When speech separation is applied at the front-end of any voice recognition system increases the performance efficiency of that particular system. In this paper we propose a system for single channel speech separation by combining empirical mode decomposition (EMD) and multi pitch information. The proposed method is completely unsupervised and requires no knowledge of the underlying speakers. In this method we apply EMD to short frames of the mixed speech for better estimation of the speech specific information. Speech specific information is derived through multi pitch tracking. To track multi pitch information from the mixed signal we apply simple-inverse filtering tracking and histogram based pitch estimation to excitation source information along with estimating the number of speakers present in the mixed signal.     

Enablers That Help Foreign Architectural, Engineering, and Construction Firms Win Construction Contracts in China

With China’s fast economic growth and entry into the World Trade Organization (WTO), more foreign architectural, engineering, and construction (AEC) firms are expected to venture into this huge and attractive market. This paper explores the important strategies to help foreign AEC firms clinch construction projects in China. Using a questionnaire survey approach complemented by in-depth interviews, it was found that firms need to pay more attention to the market and working conditions in China and to strengthen their own capabilities. To win projects in China, foreign AEC firms should also be able to offer project financing services. The findings are useful to foreign AEC firms because it may help them win projects in the Chinese construction industry.     

Differential scanning calorimetric and free volume study of reactive compatibilization by EPM‐g‐MA of poly(trimethylene terephthalate)/EPDM blends

Differential scanning calorimetry (DSC) and positron annihilation lifetime measurements have been carried out to study the effect of the compatibilizer maleic anhydride grafted ethylene propylene copolymer (EPM‐g‐MA) in poly trimethylene terephthalate and ethylene propylene diene monomer (PTT/EPDM) immiscible blends. The DSC results for the blends of 50/50 and 30/70 compositions show two clear glass transition temperatures, indicating that the blends are two‐phase systems. With the addition of compatibilizer, the separation between the two glass transitions decreased, suggesting an increased interaction between the blend components with compatibilizer. At 5 wt % of compatibilizer, the separation between the T_gs reduced in both 50/50 and 30/70 blends. The positron results for the blends without compatibilizer showed an increase in relative fractional free volume, as the EPDM content in the blend is increased. This suggests the coalescence of free volume of EPDM with the free volumes of PTT due to phase separation. However, the effect of compatibilizer in the blends was clearly seen with the observed minimum in free volume parameters at 5% of the compatibilizer, further suggesting that this percent of compatibilizer seems to be the optimum value for these blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 740–747, 2006     

Influence of Ho-Doping on the Electromagnetic Field-Dependent $E$–$J$ Characteristics of (Bi,Pb)-2212 Superconductor

The magnetic field (B ) dependence of electric field versus transport current density (E-J characteristics) of Bi_1.6Pb_0.5Sr_2-xHo_xCa_1.1Cu_2.1O_8+delta superconductor was studied for x from 0.000 to 0.200. The behavior of supercurrent flow under magnetic fields in Ho-doped (Bi,Pb)-2212 is explained using thermally activated flux-creep. The n -value and characteristic pinning energy ( U_c) estimated from E-J characteristics show that at applied fields, the flux-lines in Ho-doped samples are in the glass-state. A correlation is observed between n -index and J_c of doped samples. The highly enhanced critical current density (J_c) and n-index in both self- and applied-fields due to Ho-doping is of great scientific and technological significance.     

Aeroelastic time response analysis of thin airfoils by transonic code LTRAN2

A computer based numerical procedure is used to perform aeroelastic time response analysis of thin airfoils oscillating with single and two d.o.f.'s in two-dimensional, unsteady, low-frequency, small-disturbance, transonic potential flow. A computational transonic code LTRAN2 based on fully implicit time integration scheme is employed to obtain the aerodynamic forces. Structural equations of motion and the aerodynamic equations are integrated simultaneously by a numerical method. Results are first obtained for a time response example for a flat plate oscillating at M_∞ = 0.7 with (1) a single pitching d.o.f.; (2) a single plunging d.o.f.; and (3) two d.o.f.s—plunging and pitching. A parallel set of results are also obtained based on subsonic aerodynamic theory for comparison. The agreement is good. Results are then obtained for a time response example for a NACA 64A006 airfoil pitching and plunging at M_∞ = 0.85 which was found to give the lowest flutter speed for the case considered. The parameters that result in neutrally stable response agree with those found in a separate flutter analysis. It was found through comparison between flutter results and response analysis that the principle of superposition of airloads is valid for the present example cases. The results also include the effect of altitude on aeroelastic response.     

Build-Operate-Transfer-Type Procurement in Asian Megaprojects

Lessons are drawn from the recent resurgence in public-private partnerships for the procurement of large scale infrastructure, with a focus on Asian megaprojects. BOT (build-operate-transfer)-type win-win cooperation aligns well with the paradigm shift that has repeatedly been called for in addressing construction industry shortfalls. However, the many volatile variables involved and the limited experience in dealing with the special risks encountered highlights the need for decision support frameworks to evaluate and select the optimal from among: (1) potential BOT-type projects; (2) prospective franchisees; and (3) innovative project financing packages. Such frameworks should include appropriate success criteria and indicators for their evaluation. Benchmarking of good practices would establish reasonable ranges of values for such indicators. Identification of critical success factors, classifications of common risks, and comparisons of recent experiences on BOT-type projects lead to recommendations for the development of a “BOT body of knowledge” with related guidelines and toolkits. These would assist both public and private sector decision makers considering BOT-type modalities to attain multiple win-win-win targets that benefit their respective interests, as well as those of the general public end users.     

Polycondensation in liquid crystalline phases of nonionic surfactants. Kinetics and morphology

We have investigated acid-catalyzed polycondensation of alkoxysilane monomers in liquid crystalline phases of nonionic CnEm surfactants. The liquid crystalline phase is retained when the monomers polymerize. The high molecular weight molecules formed phase separate from the mesophase and are subsequently organized by it to form micron-sized particles. A variety of particle morphologies are formed by organization of the polymer particles in the mesophase. For condensation of dimethyldimethoxysilane (DMS, with trimethoxysilane, TMS as crosslinker) in hexagonal and lamellar phases, specific reaction conditions, viz. slow condensation kinetics and low crosslink density, give rod-like particles in hexagonal phases and sheet-like structures in lamellar phases. However, when higher acid concentrations are used, the reaction kinetics accelerates and irregular particles form. Irregular particles also form when the fraction of trifunctional crosslinker is increased, and finally complex flower-like structures form for condensation of trimethoxysilane in the hexagonal phase. The particle morphology formed is crucially dependent on the details of the polycondensation rate, crosslinker density and surfactant-monomer/oligomer interactions.