Manuel Martins Barata

NFC Technologies in Mobile Phones and Emerging Applications

The main purpose of this paper is to introduce some new non-conventional applications to allow the exploitation of today’s mobile phone resources, namely their connectivity capabilities to other devices. There is a great potential for applications to take advantage of these available resources, to perceive and interact with the world around us, namely to serve as a user interface to interact with controlled devices. Recently beyond the necessary speaker and microphone, cell phones incorporate more sensing, processing and storage capabilities as well as alternative communication system, e.g. digital camera, Bluetooth. This paper addresses, in particular, the Near Field Communication (NFC) incorporated in cell phones and enumerates some of its main promising applications like in device monitoring and control.

Reliable and secure communications infrastructure for virtual enterprises

The virtual enterprise paradigm is the key for small and medium enterprises (SMEs) to enter into the business-to-business electronic commerce. Nevertheless SMEs require a reliable infrastructure connecting transparently to the global network of enterprises their IT application tools implementing the internal business processes. Such infrastructure is deeply grounded on a communication infrastructure that might offer operative and management mechanisms able to cope with the complexity of the underlying heterogeneous computational and communication available resources. Beyond information communication security (privacy, integrity, and authentication), an operating reliable infrastructure to manage information communication is required. The SME business cannot support the great vulnerability to failures presented by a distributed system made of heterogeneous technologies. The PRODNET Communication Infrastructure aims to offer beyond a secure and high availability communication infrastructure, a set of features to cope with such distribution and heterogeneity implemented by a flexible communication management module. Considering that SMEs do not have their own IT support, the PRODNET Communication Infrastructure also offers remote management/maintenance capabilities.

Simple and Complex Logical Functions in a SiC Tandem Device

In this study we demonstrate the basic AND, OR and NOT logical functions based on SiC technology. The device consists of a p-i’(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure with low conductivity doped layers. Experimental optoelectronic characterization of the fabricated device shows the feasibility of tailoring channel bandwidth and wavelength by optical bias through illumination at the back and front sides. Results show that, front background enhances the light-to-dark sensitivity of the long and medium wavelength range and strongly quenches the others. Back violet background has the opposite behavior; it enhances the magnitude in short wavelength range and reduces it in the long ones. This nonlinearity provides the possibility for selective removal or addition of wavelengths.

Multilayered a-SiC:H device for Wavelength-Division (de)Multiplexing applications in the visible spectrum

A multiplexer is a device that combines two or more signals onto a single output without losing their specificity. In this paper we present results on the use of multilayered a-SiC:H heterostructures either as wavelength-division multiplexing or demultiplexing device (WDM). The WDM is a glass/ITO/a-SiC:H (p-i-n)/ a-SiC:H(-p) /Si:H(-i)/SiC:H (-n)/ITO double heterostructure which faces the modulated light incoming together from different beams, each one with a specific wavelength and period. By reading out, at different applied bias, the photocurrent generated by all the incoming optical carriers, the information is multiplexed or demultiplexed and can be transmitted and recovered again. The devices were characterized through spectral response measurements, under different electrical bias and frequencies. Results show that in the multiplexing mode the output signal is balanced by the wavelength of each incoming optical carrier and modulated by their frequencies. In the demultiplexing mode the photocurrent is controlled by the applied voltage and optical bias allowing to regain the transmitted information. An electrical model is presented to explain the device operation.

Interoperability Among Its Systems with Its-Ibus Framework

This paper presents and discusses the extended Via-Verde business model from the point of view of the underlying requirements for the virtual business processes. The extension of Via-Verde concept to other services beyond the motorway toll collection has increased the number of independent companies involved. The complex networked scenario resulted on a proposal of an intelligent transport system — interoperability bus (ITS-IBus) (Gomes et. al. 2003) (Osorio, et. al. 2003-a) aiming to promote a generalized interoperability among heterogeneous (multi-vendor) technological subsystems. The ITS-IBus initiative has been developing since then, a reference implementation of a peer-to-peer service based framework with pluggable feature and a set of common agreed interfaces for coupling different technological systems. An important objective is to increase the quality of the offered services by establishing a flexible execution and coordination framework for the collaborative distributed business processes.

Optoelectronic Digital Capture Device Based on Si/C Multilayer Heterostructures

Combined tunable WDM converters based on SiC multilayer photonic active filters are analyzed. The operation combines the properties of active long-pass and short-pass wavelength filter sections into a capacitive active band-pass filter. The sensor element is a multilayered heterostructure produced by PE-CVD. The configuration includes two stacked SiC p-i-n structures sandwiched between two transparent contacts. Transfer function characteristics are studied both theoretically and experimentally. Results show that optical bias activated photonic device combines the demultiplexing operation with the simultaneous photodetection and self amplification of an optical signal acting the device as an integrated photonic filter in the visible range. Depending on the wavelength of the external background and irradiation side, the device acts either as a short- or a long-pass band filter or as a band-stop filter. The output waveform presents a nonlinear amplitude-dependent response to the wavelengths of the input channels. A numerical simulation and a two building-blocks active circuit is presented and gives insight into the physics of the device.

SiC Multilayer Photonic Structures with Self Optical Bias Amplification

Characteristics of tunable wavelength pi’n/pin filters based on a-SiC:H multilayered stacked cells are studied both experimental and theoretically. Results show that the device combines the demultiplexing operation with the simultaneous photodetection and self amplification of the signal. An algorithm to decode the multiplex signal is established. A capacitive active band-pass filter model is presented and supported by an electrical simulation of the state variable filter circuit. Experimental and simulated results show that the device acts as a state variable filter. It combines the properties of active high-pass and low-pass filter sections into a capacitive active band-pass filter using a changing photo capacitance to control the power delivered to the load.

Open Multi-Technology Service Oriented Architectur for “Its” Business Models: The ITSIBus Etoll Services

The development of integrated solutions made of systems based on different technologies, adopting different implementation approaches and different versions is a complex challenge. The lack of standards or differences in implementations when they exist, are important obstacles to the construction of integrated, flexible and agile solutions. The incorporation of systems from different vendors and systems that evolve to answer innovation processes, suggests the advantage for a multi-technology systems strategy. This paper discusses the ITSIBus approach based on, a multi-technology service oriented infrastructure where specialized pluggable systems run services following a peer to peer architecture. The multi-technology approach is based on the discussed System Broker concept. The agility required by a crescent number of collaborative business process requires an advanced flexibility from the ICT technological infrastructure. The ITSIBus approach is also discussed as a grounding platform to support enterprise collaborative networks considering that services in different companies are based on different technologies.

Light Memory Operation Based on a Double Pin SiC Device

Experimental optoelectronic characterization of a p-i’(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure with low conductivity doped layers shows the feasibility of tailoring channel bandwidth and wavelength by optical bias through back and front side illumination. Front background enhances light-to-dark sensitivity of the long and medium wavelength range, and strongly quenches the others. Back violet background enhances the magnitude in short wavelength range and reduces the others. Experiments have three distinct programmed time slots: control, hibernation and data. Throughout the control time slot steady light wavelengths illuminate either or both sides of the device, followed by the hibernation without any background illumination. The third time slot allows a programmable sequence of different wavelengths with an impulse frequency of 6000Hz to shine upon the sensor. Results show that the control time slot illumination has an influence on the data time slot which is used as a volatile memory with the set, reset logical functions.

Seven channel wavelength demultiplexer using a tandem a:SiC-H/a:Si-H photo sensor

optically biased by ultra-violet illumination of the front or back surfaces. The front surface is also used for several pulsed single wavelength signals within the visible range. Experimental results show that the ultra-violet bias illumination at the front surface of the device enhances wavelengths longer than 500 nm while quenching the wavelengths shorter than 500 nm. The opposite happens when the bias is set at the back surface of the device; wavelengths shorter than 500 nm are enhanced while the ones above are quenched. Several digital applications have been built using the p’inpin device. This paper focuses on the use of the pi’npin device for seven channel Wavelength Division Multiplexing (WDM) digital communication using Manchester coded signals, with a single wavelength for each channel. The seven channels form a frame with 7*256 bits with a preamble for signal intensity and synchronization purposes. Results show that the clustering of the received signal enables the successful recovery of the seven channel data using the front and back illumination of the surfaces of the pi’npin photo device.