Improvement of photoelectrochemical and optical characteristics of MEH-PPV using titanium dioxide nanoparticles

The use of bulk heterojunctions can increase the efficiency of exciton dissociation in polymer-based photovoltaics. We prepared and characterized bulk heterojunctions of poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and titanium dioxide nanoparticles deposited by spin coating on indium tin oxide substrates. The surface morphology of the MEH-PPV+TiO₂ composite films revealed that addition of TiO₂ nanoparticles increased the film roughness. The effect of TiO₂ nanoparticles on the photoelectrochemical and optical characteristics of MEH-PPV polymer heterojunctions was studied. Addition of TiO₂ nanoparticles improved the absorbance of MEH-PPV composite films. Moreover, the photocurrent of the composite devices increased with the TiO₂ nanoparticle concentration. These observations provide an insight into new approaches to improve the light collection efficiency in photoconductive polymers.     

Model based real time monitoring for collision detection of an industrial robot

This paper deals with a model based real-time virtual simulator of industrial robot in order to detect eventual external collision. The implemented method concerns a model based Fault Detection and Isolation used to determine any lock of motion from an actuated robot joint after contact with static obstacles. Online implementation has been done in order to validate the proposed approach.     

Service level agreement in optical networks

This article proposes a Service Level Agreement applied to the optical domain (O-sla), which is expected to be the near and long term network technology thanks, among other things, to the great bandwidth capacity offered by optical devices. After an exposition of the rationale behind an optical sla, parameters which could enter in thisO-sla, as well as their values for four classes of services, are proposed. Different client (wavelength or sub-wavelength) and services types (from leased wavelength to bandwidth on demand) are distinguished when necessary.     

Study of lithium behaviour in Si(Li) detectors

In this paper we describe the fabrication of a conventional lithium compensated silicon detector (Si(Li)) realized on Topsil silicon with bulk resistivity 0.9 to , using the process of ion drift introduced by Pell. Preliminary results of electrical and nuclear characterization are shown. A leakage current value of 4 pA is obtained under reverse bias voltage of , at pressure of and 113 K. An alpha test using triple source ²⁴¹Am, ²³⁹Pu, ²³³U was carried and a resolution on ²⁴¹Am peak around 42 keV was obtained with this type of detector. The fabricated detector present a good electrical and nuclear characteristics that can be used in X-ray spectrometry and widespread applications in research science, environment monitoring and natural radioactivity. The main contribution of this work is the demonstration of an easy-to-implement, low cost detector set that can be achieved with an inexpensive n⁺p diode.