Low overhead assignment of symbolic coordinates in sensor networks

Approximate information on the location of nodes in a sensor network is essential to many types of sensor network applications and algorithms. In many cases, using symbolic coordinates is an attractive alternative to the use of geographic coordinates due to lower costs and lower requirements on the available location information during coordinate assignment. In this paper, we investigate different possible methods of assigning symbolic coordinates to sensor nodes. We present a method based on broadcasting coordinate messages and filtering using sensor events. We show in the evaluation that this method allows a reliable assignment of symbolic coordinates while only generating a low overhead.     

关于聚焦诱导立体显示器的研究

传统的立体显示是通过聚焦诱导,进行深度视觉模糊调节,从而达到立体视觉效果。现在,科研人员开发了一种新型技术——聚焦修正。通过这项技术,将聚焦诱导和深度视觉模仿同步进行,可以使立体景象显示更加快速、准确,同时减轻观看者的视觉疲劳度。     

Effect of wet chemical substrate pretreatment on the growth behavior of Ta(N) films deposited by thermal ALD

The deposition of ultra thin Ta(N) films by ALD is a possibility to achieve conformal film thickness and suitable step coverage for microelectronic applications. Due to the sorption of a precursor molecule to the substrate surface, the chemical interface conditions are important. In the present study selected substrate pretreatments were investigated by in situ XPS and spectroscopic ellipsometry in reference to the amount of carbon containing contamination and oxygen and in reference to the ALD growth rate of Ta(N) films. Furthermore, surface roughness was measured by AFM and will be discussed in dependence on the individual pretreatment and the ALD Ta(N) cycle number.     

DC and RF performance of GaAs MESFET fabricated on silicon substrate using epitaxial lift-off technique

GaAs MESFETs have been fabricated on a silicon substrate using a molecular beam epitaxy grown film detached from its growth substrate and attached on a silicon substrate covered with a dielectric. The device processing is done on the silicon substrate. The MESFETs exhibit I/sub DSS/=130 mA/mm, g/sub m/=135 mS/mm and for 1.3 mu m gate length unity current gain cut-off frequency f/sub T/ of 12 GHz. Excellent device isolation with subpicoampere leakage currents is obtained.<>     

Wind turbine speed control of a contactless piezoelectric wind energy harvester

ABSTRACT

Wind turbine control is an important task to make the electricity generation secure in terms of energy demand and machine safety. It also yields to control the desired power level and optimized energy because of the assignment of turbine speed. The contactless piezoelectric wind energy harvester (CPWEH) used in this study has three piezoelectric layers located around the shaft with 120 degrees apart and they are buckled by the magnetic force without any physical contact. The superiority of this device is to generate energy for low wind speeds such as 1.5 m/s. However, for high speeds, high total harmonic distortions (THDs) govern the waveforms, thus controlling the turbine speed becomes necessary for optimizing the output power. Encouraged by this, a small low inertia dc generator is coupled with the wind turbine, and the generator terminals are connected to a resistor through a power switch to generate a braking torque that opposes to wind speed direction. By controlling the switch properly, turbine speed is ensured to remain within a certain band, which accordingly prevents the turbine from rotating very fast at damaging wind speeds. Several experiments are performed on the developed CPWEH with/without the presented control scheme which prove the existence of promising performance of our proposal.     

Die Wirkung von α-Amylasen auf β-Cyclodextrin und der Nachweis von α-Amylasefremdaktivitäten in ausgewählten Enzympräparaten

The action of α-amylases on β-cyclodextrin and the evidence of foreign activity of α-amylase in selected preparations of enzymes The interaction between cyclodextrins and α-amylases taken from different sources is discribed contradictious in the literature. Some α-amylases e.g. isolated from Aspergillus oryzae, porcine pancreas and saliva hydrolized cyclodextrins to glucose. The hydrolysis of cyclodextrins catalysed by α-amylase from Bacillus species have been described conflicting. In this paper the action of hydrolysis of different preparations of α-amylases on β-cyclodextrin have been investigated. It has been shown that Rohalase M3 (α-amylase from Aspergillus niger) cleaves the ring of β-cyclodextrin. 2 α-amylases from Bacillus subtilis are not able to hydrolyse β-cyclodextrin. The reasons for the different actions of hydrolysis have been discussed with size and structure of the active centre of the enzymes. Moreover, different preparation of hydrolysis have been tested on secondary activity of α-amylase. 2 glucoamylases from Aspergillus oryzae have been shown secondary activity of α-amylase. With the hydrolases α-glucosidase from fungies, β-amylase from malt, saccharase from yeast, invertase from S. cerevisiae and pullulanase from Aerobacter aerogenes no cleavage of the ring of β-cyclodextrin could be detected.     

Low-power low-noise active mixers for 5.7 and 11.2 GHz usingcommercially available SiGe HBT MMIC technology

The authors demonstrate the application of a commercially available SiGe heterojunction bipolar transistor monolithic microwave integrated circuit technology to active mixers in future communication systems at 5.7 GHz and above. This technology can be used to realise circuits with less than 50 mW power consumption, conversion gains above 15 dB and small double sideband noise figures of 3.6 and 9.4 dB for 5.7 and 11.2 GHz Gilbert cell mixer circuits, respectively     

Roadmapping the Technological Future of Electricity

A future-scanning collaboration orchestrated by the Electric Power Research Institute has sought to illuminate the technologies whose development will be needed to attain the “2 percent” solution of improvements in economic productivity, energy efficiency and agricultural productivity necessary for global sustainability.     

Soft Iron/Silicon Composite Tubes for Magnetic Peristaltic Pumping: Frequency‐Dependent Pressure and Volume Flow

The combination of force and flexibility enables controlled and soft movements. In sharp contrast, presently used machines are solid and mostly based on stiff driveshafts or cog wheels. Magnetic elastomers are realized through dispersion of small particles in polymer matrices and have attracted significant interest as soft actuators for controlled movement or conveying and are particularly attractive candidates for magnetic pump applications. At present, low magnetic particle loading and thus limited actuator strength have restricted the application of such materials. Here, the direct incorporation of metal microparticles into a very soft and flexible silicone and its application as an ultra‐flexible, yet strong magnetic tube, is described. Because metals have a far higher saturation magnetization and higher density than oxides, the resulting increased force/volume ratio afforded significantly stronger magnetic actuators with high mechanical stability, flexibility, and shape memory. Elliptical inner diameter shape of the tubing allowed a very efficient contraction of the tube by applying an external magnetic field. The combination of magnetic silicone tubes and a magnetic field generating device results in a magnetic peristaltic pump.     

A modelling language for cooperative plans in highly dynamic domains

Cooperative behaviour is one of the challenges most pronounced in the RoboCup Middle Size League. Especially the dynamic nature of the domain, which calls for swift adaptation by each robot and the team as a whole, is a distinctive property of the league. The ability to establish highly responsive teamwork while facing unreliable communication and sensory noise is a key to successful soccer teams. Moreover, modelling such responsive, cooperative behaviour is difficult. In this work, we specify a novel model for cooperative behaviour geared towards highly dynamic domains, focussing on the language syntax and semantics. In our approach, agents estimate each other’s decision and correct these estimations once they receive contradictory information. We provide a comprehensive approach for agent teamwork featuring intuitive modelling capabilities for multi-agent activities, abstractions over activities and agents, and a clear operational semantics. Moreover, we briefly present a graphical modeling tool for cooperative strategies, which is based directly on the theory laid out, together with a practical framework for executing said strategies. We show experimentally the responsiveness and coherence of the resulting team play.