Stress relaxation of La1/2Sr1/2MnO3 and La2/3Ca1/3MnO3 at solid oxide fuel cell interfaces

Interfacial stress is thought to have significant effects on electrical and oxygen transport properties in thin films of importance in solid oxide fuel cell applications. We investigate how in-plane biaxial stress modifies the electronic structure of La_2/3Ca_1/3MnO₃ and La_1/2Sr_1/2MnO₃ thin films prepared by pulsed laser deposition on three different substrates to vary the in-plane stress from tensile to compressive. The electronic structure was probed by X-ray absorption spectroscopy of the Mn L_2,3-edge to characterize the interfacial disruption in this region in an element-specific, site-specific manner. The compressive or tensile interfacial strain modifies the relative concentrations of La and Sr in the interfacial region in order to achieve a better lattice match to the contact material. This atomic migration generates an interfacial region dominated by a compound with a single valency for the transition metal ion, resulting in a severe barrier to oxygen and electron transport through this region.     

Three-dimensional obstacles for bacterial surface motility

Twitching motility enables bacteria to move over surfaces using type IV pili as grappling hooks. Here it is shown that the motility of the round Neisseria gonorrhoeae as well as of rod-shaped Myxococcus xanthus is guided by elevations with dimension and depth corresponding to the size of the bacteria.     

Numerical Simulation of Carbon Redistribution during Steel Composite Production

During heat treatment of cladded steel composites, element redistribution may occur between the various plating materials. Depending on alloy composition and the particular time–temperature profile, Carbon (C) diffusion between the plating materials is observed. Herein, C diffusion between different layers of roll-cladded steel composites during typical production routes is numerically simulated with the thermokinetic software package MatCalc. Two material combinations, 340LA–22MnB5 and 340LA–34MnB5, are compared with experimental results of large-scale manufactured steel composite material at different production steps, from hot strip to hardened cold strip material. The simulation agrees qualitatively and quantitatively well with the experimental results. It is demonstrated that even short heat treatment intervals can have significant influence on the C redistribution within the steel composite.     

Centrifuges and Their Application for Biological Experiments in Space

The need for an in-orbit 1×g control originated from the fact that Space radiation or other environmental factors of Space flight could not be excluded as cause for the effects on biological systems that were mainly interpreted as effects of the weightlessness environment. Indeed, in many experiments the 1×g reference centrifuge on board revealed the same data as the 1×g controls on ground, proving the lack of gravity was causing the results. In other cases, the reference centrifuge data were intermediate or clearly different to the ground data which was either due to interrupted 1×g conditions on board or to other, sometimes not well understood factors. This triggered also the development of sophisticated hardware allowing the start, i.e. the transition from 1×g to 0×g, or the termination of the experiment without stopping the centrifuge. Recently developed facilities provide also a complete life support system on the centrifuge rotor. Besides the in-flight 1×g control, acceleration experiments required a centrifuge for determination of threshold values in orbit.     

A self-adaptive heterogeneous multi-core architecture for embedded real-time video object tracking

Sequential Monte Carlo (SMC) represents a principal statistical method for tracking objects in video sequences by on-line estimation of the state of a non-linear dynamic system. The performance of individual stages of the SMC algorithm is usually data-dependent, making the prediction of the performance of a real-time capable system difficult and often leading to grossly overestimated and inefficient system designs. Also, the considerable computational complexity is a major obstacle when implementing SMC methods on purely CPU-based resource constrained embedded systems. In contrast, heterogeneous multi-cores present a more suitable implementation platform. We use hybrid CPU/FPGA systems, as they can efficiently execute both the control-centric sequential as well as the data-parallel parts of an SMC application. However, even with hybrid CPU/FPGA platforms, determining the optimal HW/SW partitioning is challenging in general, and even impossible with a design time approach. Thus, we need self-adaptive architectures and system software layers that are able to react autonomously to varying workloads and changing input data while preserving real-time constraints and area efficiency. In this article, we present a video tracking application modeled on top of a framework for implementing SMC methods on CPU/FPGA-based systems such as modern platform FPGAs. Based on a multithreaded programming model, our framework allows for an easy design space exploration with respect to the HW/SW partitioning. Additionally, the application can adaptively switch between several partitionings during run-time to react to changing input data and performance requirements. Our system utilizes two variants of a add/remove self-adaptation technique for task partitioning inside this framework that achieve soft real-time behavior while trying to minimize the number of active cores. To evaluate its performance and area requirements, we demonstrate the application and the framework on a real-life video tracking case study and show that partial reconfiguration can be effectively and transparently used for realizing adaptive real-time HW/SW systems.     

Observational Study of Clogging Specimens from the Tundish Well Showing Origin and Growth of a Clog in an Al-Killed Ti-Alloyed Steel Cast

Metallurgical and Materials Transactions B - Post-mortem tundish skull samples of Ti-alloyed, Al-killed IF steel have been studied regarding the formation of clogging. By using modern...     

Professional Design Component for Civil Engineering Curriculums

The Accreditation Board for Engineering and Technology has adopted a revised set of accreditation criteria that is designed to assure that graduates of accredited programs are prepared to enter the practice of engineering. The proposal also specifies that engineering programs must demonstrate that their graduates have an understanding of professional practice issues in addition to the ability to design civil engineering projects by taking various realistic constraints under consideration. The findings of this study indicate that engineering undergraduate and graduate students as well as practitioners perceive that three constraints that represent the traditional technical aspect of engineering are of great importance for design projects. They include engineering codes and standards, economic factors, and manufacturability (constructability). In contrast, two constraints received lower ratings. They include social ramifications and political factors. Overall, 60% of the Accreditation Board for Engineering and Technology recommended design constraints are rated by students and practitioners with a composite score ? 3.0. This may be interpreted as strong support for the Engineering Criteria 2000 design requirements.     

International Labor Productivity Factors

The construction industry is increasingly involved with international projects requiring the services of nonskilled and skilled workers throughout the world. Data concerning the productivity of these workers, therefore, is a critical need for the industry. The purpose of this article is to present national labor productivity factors for 47 various countries in Central and South America, Europe, the Middle East, and Asia. In addition, specific variables affecting national and international productivity are reviewed.     

Climatic Effects on Construction

The results of an investigation designed to determine the relationship between overall construction productivity, and temperature and humidity are presented. Data from the following activities or crafts, or both, were employed: excavation (manual), erection, masonry, electrocal, carpentry, laborers, and excavation (equipment). Two nonlinear equations were determined, one for cold or cool weather (R2? = ?0.62) and another for hot or warm weather (R2? = ?0.64). The overall findings indicate that below ?10?°F and above 110?°F it is difficult to achieve efficient construction operations. In addition to productivity data, the health hazards, possible preventive measures, and acclimatization of workers to severe environments are examined.