Multidimensional M-PSK trellis codes for fading channels

This paper investigates the code search problem for trellis-coded multidimensional phase modulation for Rayleigh fading channels. New set partitionings for multiple phase-shift keying (M-PSK) are proposed using the effective code length (ECL) and the minimum product distance (PD) as the code design criteria. By using these set-partitionings rules, new multidimensional codes which are optimum for Rayleigh fading channels are constructed. The proposed codes compare favorably with the existing multidimensional trellis codes on fading channels in terms of bit error performance. The bit error performance is evaluated by simulation     

Energy requirements for a swimming pool through a water-atmosphere energy balance

The methodology displayed here is to calculate the energy requirements for heating a swimming pool to a desired temperature. This methodology consists of an energy balance between water-atmosphere as is used in the temperature evaluation of cooling ponds in power plants. Different mathematical expressions are given to calculate such a balance. It is necessary to know the month of the year, the ambient temperature, relative humidity, wind velocity, and solar radiation. With these parameters it is possible to know the natural temperature of the water, natural evaporation, energy needed to reach a determined swimming pool temperature and the evaporation of the heated pool.     

An Evolutionary Method for Synthesizing Low-Sensitivity Lossless Matching Networks

Whereas the present practice of designing matching networks for antennas is limited to conventional topologies, requiring a significant amount of domain knowledge, evolutionary algorithms can be used for automatically identifying unconventional designs that are more effective than would otherwise be developed. In this work, an automatic method to design lossless matching networks driven by an evolutionary algorithm (EA) that considers the sensitivities of the network parameters during the synthesis process is presented. To this end, a closed-form expression for the transducer power gain (TPG) sensitivity with respect to the component values is employed in such a way that the effects of the components tolerance on the matching network performance can easily be quantified. A 3D data structure based on the adjacency matrix is conveniently used to represent any type of network topologies. The proposed EA employs a novel set of topology variation operators, tailored for changing the circuit topology, and an association step, with the aim of reducing the number of nodes of the matching circuit. The efficiency of the proposed EA is tested in the synthesis of an impedance matching network for a VHF monopole whip antenna. This study’s results indicate a matching bandwidth improvement, a more uniformly distributed TPG along the operation frequency band and a more stable TPG regarding the components tolerance compared to the results obtained by previous approaches.     

Information and Telecommunications Project for a Digital City: A Brazilian case study

Making information and telecommunications available is a permanent challenge for cities concerned to their social, urban and local planning and development, focused on life quality of their citizens and on the effectiveness of public management. Such a challenge requires the involvement of everyone in the city. The objective is to describe the information and telecommunications project from the planning of a digital city carried out in Vinhedo-SP, Brazil. It was built as a telecommunications infrastructure of the kind of “open access metropolitan area networks” which enables the integration of citizens in a single telecommunications environment. The research methodology was emphasized by a case study which turned to be a research-action, comprising the municipal administration and its local units. The results achieved describe, by means of a methodology, the phases, sub-phases, activities, approval points and resulting products, and formalize their respective challenges and difficulties. The contributions have to do with the practical feasibility of the project and execution of its methodology. The conclusion reiterates the importance of the project, collectively implemented and accepted, as a tool to help the management of cities, in the implementation of Strategic Digital City Projects, in the decisions of public administration managers, and in the quality of life of their citizens.     

On the impact of physical layer awareness on scheduling and resource allocation in broadband multicellular IEEE 802.16 systems [Radio Resource Management and Protocol Engineering for IEEE 802.16]

Multicellular networks based on the IEEE 802.16 standard appear to be very promising candidates to provide end users with broadband wireless access. However, they also pose interesting challenges in terms of radio resource management, where several design choices are not specified in the standard, intentionally left open to implementors. For this reason, we focus in this article on scheduling and resource allocation, and investigate how they could operate in a cross-layer fashion. In particular, we describe the principles of joint scheduling and resource allocation for IEEE 802.16 operating in AMC mode, and discuss the critical role played by physical layer considerations, especially intercell interference estimation and channel state awareness, in the obtained performance. This leads to identifying key open issues and possible general solutions     

Dihydroazulene Photoswitch Operating in Sequential Tunneling Regime: Synthesis and Single‐Molecule Junction Studies

Molecular switches play a central role for the development of molecular electronics. In this work it is demonstrated that the reproducibility and robustness of a single‐molecule dihydroazulene (DHA)/vinylheptafulvene (VHF) switch can be remarkably enhanced if the switching kernel is weakly coupled to electrodes so that the electron transport goes by sequential tunneling. To assure weak coupling, the DHA switching kernel is modified by incorporating p‐MeSC₆H₄ end‐groups. Molecules are prepared by Suzuki cross‐couplings on suitable halogenated derivatives of DHA. The synthesis presents an expansion of our previously reported bromination–elimination–cross‐coupling protocol for functionalization of the DHA core. For all new derivatives the kinetics of DHA/VHF transition has been thoroughly studied in solution. The kinetics reveals the effect of sulfur end‐groups on the thermal ring‐closure of VHF. One derivative, incorporating a p‐MeSC₆H₄ anchoring group in one end, has been placed in a silver nanogap. Conductance measurements justify that transport through both DHA (high resistivity) and VHF (low resistivity) forms goes by sequential tunneling. The switching is fairly reversible and reenterable; after more than 20 “ON‐OFF” switchings, both DHA and VHF forms are still recognizable, albeit noticeably different from the original states.     

Consistency,availability, and partition tolerance in blockchain: a survey on the consensus mechanism over peer-to-peer networking

Annals of Telecommunications - Blockchain is a disruptive technology that relies on the distributed nature of the peer-to-peer network while performing an agreement, or consensus, a mechanism to...