Digital In-Line Holography as a Three-Dimensional Tool to Study Motile Marine Organisms During Their Exploration of Surfaces

The swimming patterns of zoospores of the green alga Ulva linza in the vicinity of a surface were investigated by digital in-line holography. Full 3D motion patterns were retrieved from measurements and the traces obtained were compared with known swimming patterns of spores of the brown alga Hincksia irregularis and the green alga Ulva linza as seen in a conventional optical microscope. Quantitative information such as swimming velocity was calculated from the 3D traces. The results demonstrate the potential of digital in-line holography to image and quantify exploratory patterns of behavior of motile spores close to surfaces. This technique can give detailed insight into mechanisms of surface colonization by spores and larvae of fouling organisms in response to changes in surface properties.     

Crystallographic Texture and Thermal Conductivity of Zirconia Thermal Barrier Coatings Deposited on Different Substrates

The crystallographic texture and thermal conductivity of zirconia coatings deposited by electron beam evaporation on a variety of substrates have been measured. It was found that the thermal conductivity of coatings deposited at the same temperature was independent of whether they were deposited on polycrystalline alumina, single-crystal sapphire, single-crystal zirconia, or fused silica. The room-temperature thermal conductivity of the coatings deposited at 700°C was 0.32 W/(m·K), increasing to 1.36 W/(m·K) for coatings deposited at 1150°C. Similarly, the crystallographic texture was also independent of the substrate and had a (111) fiber texture at 700° and 900°C, switching to a (200) fiber texture by 1050°C. The exception was the coating deposited at 1150°C on (111) single-crystal zirconia which was epitaxial and exhibited a thermal conductivity of 2.46 W/(m·K). It is concluded that the properties of zirconia thermal barrier coatings are determined by the growth conditions rather than those associated with nucleation on the underlying substrate.     

Coherent multicarrier technology for implementation in the customeraccess

The use of coherent multicarrier (CMC) techniques in the integrated broadband communication network (IBCN) is proposed. Technology, implementation strategies, system engineering, system application areas, and evolution aspects are considered. The use of CMC systems for distributive and interactive services is discussed, and related CMC transmission and switching issues are considered. Details on the realization of a CMC demonstrator for a customer access and plans for implementation of the engineered equipment in field trials are presented     

Embedding remote experimentation in power engineering education

Engineering education by its nature is a costly program in university environments. Perhaps the most costly component is the laboratory facility, usually consisting of specialized equipment. Effective instruction of some topics in power engineering education requires experience with actual equipment, rather than small-scale replicas or simulation. In this paper, a new laboratory approach is described, as implemented in a virtual, Internet-based, experimentation platform. This virtual laboratory (VLab) utilizes real equipment distributed among multiple universities from which remotely located students can perform experiments. The software solution is a multiuser, client-server architecture developed in the LabVIEW environment. Implementation details including video, chat, archiving, and the hardware and software platforms are presented in the paper. An example presented herein is the study of current and voltage waveforms while controlling relays and low-voltage contactors. The applications have been tested with student teams enrolled in the electrical engineering department of Politehnica University of Bucharest and the power engineering program at Arizona State University.     

Present and Future Trends and Needs in Electric Power Quality Sensors and Instrumentation

Sensors and instrumentation systems form an important part of power quality assessment and preservation. In this paper, the present and future trends in power quality instrumentation are discussed and the present capabilities are identified (e.g., bandwidth, dynamic range, quantities measured). Innovative methods of instrumenting nonsinusoidal voltages and currents are described, including applications of the Global Positioning System (GPS), solid state sensors, sensors that involve light and video, advanced data compression techniques, and advanced state estimation. The cost-to-benefit ratio of sensor development is evaluated in the context of the deregulated electric utility business environment.     

Bandsägen für die Steinbearbeitung – aktuelle Technologieentwicklung

Bandsawing machines for stone cutting – state of the art Due to an EU‐research‐project BaSST a new process was developed to cut slabs and tiles in granite, marble and sandstone out of a huge stoneblock by means of a bandsaw. Such natural stones are very hard, the cutting forces generated to the sawband have to be limited. This was realized with a pivoting sawband, which allows to vary the effective length of engagement depending of the dimension of the material. Simoultaneausly a sawband with diamond cutting segments was developed and tested. Over a long period of optimization a long lifetime of the sawband was reached. The end of the service life was determined by normal wear of the cutting segments and not by breakage of the sawband together with very high cutting rates and excellent cutting surfaces. The outstanding advantage of this new cutting process is a high flexibility for the production, so far unknown till now, a very good cut quality and a remarkable reduced waste of material due to the thin sawband. The number of slabs cut from a block can be doupled due to the thin kerf of the sawband. The new cutting process allows to cut slabs and tiles from a block in a very economic way and under best environmental conditions.     

Use of Satellite Technologies for Power System Measurements, Command, and Control

This paper analyzes the use of wide-area measurement technologies including satellite-based methods for the command and control of power systems. The methods studied include the global positioning system (GPS) and low earth orbit satellites (LEOS). Satellite technologies have been used in a variety of applications requiring precise timing between geographically diverse locations. The deregulation of the electric power industry is placing increased demands on power transmission system utilization. Because deregulated power systems utilize long-distance high-power exchanges, satellite-based communication systems are useful in control of geographically large interconnected power systems. In this paper, the satellite-based measurements and commands are introduced for wide-area control. With the support of wide-area signals, a multiagent supervisory-level power system stabilizer is proposed here as a potential wide-area control structure. Increased loading of transmission facilities is an impetus for accurate dynamic thermal overhead electrical conductor ratings. The application of satellite-based measurement for improving the dynamic thermal rating of overhead transmission circuits is suggested.     

A stochastic dynamical systems view of the Atlantic Multidecadal Oscillation

We provide a dynamical systems framework to understand the Atlantic Multidecadal Oscillation and show that this framework is in many ways similar to that of the El Ni?o/Southern Oscillation. A so-called minimal primitive equation model is used to represent the Atlantic Ocean circulation. Within this minimal model, we identify a normal mode of multidecadal variability that can destabilize the background climate state through a Hopf bifurcation. Next, we argue that noise is setting the amplitude of the sea surface temperature variability associated with this normal mode. The results provide support that a stochastic Hopf bifurcation is involved in the multidecadal variability as observed in the North Atlantic.