Fault diagnosis as an aid to process machine reliability

Identification of the reasons for failures of process plant machines is the first step in obtaining increased reliability. Weibull analysis of the service life obtained from maintenance records requires a minimum of only five incidents and provides an insight into the failure mechanism. Two examples are given where Weibull analysis of maintenance records helped identify the cause of failure and was instrumental in achieving enhanced reliability of process plant machines.     

Airflow in a slot-ventilated enclosure partially filled with porous boxes: Part I - Measurements and simulations in the clear region

A reduced-scale model and CFD predictions were used to investigate experimentally and numerically the airflow patterns within a ceiling slot-ventilated enclosure partially loaded with vented boxes filled by spherical objects. The experiments were carried out using laser Doppler velocimetry. Airflows around and inside porous boxes were predicted taking into account their aerodynamic interactions. This work is divided into two parts. This paper presents part I and concerns the air velocity characteristics within the jet above the boxes, while Part II deals with the air velocity characteristics inside the boxes. The results highlight the confinement effect due to the enclosure and the influence of load porosity on jet penetration, its development and hence the heterogeneity of ventilation within the enclosure. The numerical predictions obtained with the computational fluid dynamics Fluent package using the RSM turbulence model show reasonable agreement with experimental data. Predicted velocity profiles were generally within an error of 3-30% of the measured velocities.     

A DSS for integrated distribution of empty and full containers

A DSS integrating empty and full containers transshipment operations is presented, addressing the typically unbalanced export/import containers trading problem. The problem is modeled as a network, where nodes represent customers, leasing companies, harbors and warehouses, while arcs represent transportation routes. The underlying mathematical model operates in stages, first prioritizing and adjusting full containers demands considering available empty containers supplies, and then statically optimizing costs. Transportation routes are registered and dynamically controlled, cyclically, for a given time horizon. The DSS is flexible, allowing several parameters to be configured. Experimental examples using randomly generated parameters were conducted to evaluate the effectiveness of the system.     

Back and forth between continuous and discrete for the working computer scientist

This paper gives a perfect, ideal, discretization of continuous notions. This is a very convenient frame to treat continuous problems or theories with the help of a computer. This is illustrated by the conversion of algorithms using real numbers into algorithms using integers only and the founding of discrete geometry.     

B-spline explicit active surfaces: an efficient framework for real-time 3-D region-based segmentation

A new formulation of active contours based on explicit functions has been recently suggested. This novel framework allows real-time 3-D segmentation since it reduces the dimensionality of the segmentation problem. In this paper, we propose a B-spline formulation of this approach, which further improves the computational efficiency of the algorithm. We also show that this framework allows evolving the active contour using local region-based terms, thereby overcoming the limitations of the original method while preserving computational speed. The feasibility of real-time 3-D segmentation is demonstrated using simulated and medical data such as liver computer tomography and cardiac ultrasound images.     

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.     

Quantitative determination of Botrytis laccase in musts and wines by the syringaldazine test

The syringaldazine assay was adapted for quantitative determination of laccase (EC 1.10.3.2) activity from Botrytis cinerea Pers in musts and new wines. This colorimetric method is fast, specific and sensitive. It makes it possible to assess the level of contamination of crops by Botrytis cinerea. The assay can be performed in the presence of tyrosinase but the phenolic compounds of the grape must first be eliminated because of their inhibition of syringaldazine oxidation by laccase. When measured in botrytised grape, laccase activity is related to the stages of development of the fungus.     

A 1.4GS/s 9-bit 45 dB power control RFDAC for digital radio transmitters

This paper presents a high speed, 9-bit RF Digital-to-Analog Converter based on a new architecture implemented in a 0.13 μm BiCMOS process and able to adjust the output power by 45 dB to meet gain control requirements of the new communications standards with a SFDR >25 dBc. The maximum test-demonstrated frequency is 1.4 GHz and the chip dissipates <25 mW.     

Physics of Gate Modulated Resonant Tunneling (RT)-FETs: Multi-barrier MOSFET for steep slope and high on-current

A new concept of nanoscale MOSFET, the Gate Modulated Resonant Tunneling Transistor (RT-FET), is presented and modeled using 3D Non-Equilibrium Green’s Function simulations enlightening the main physical mechanisms. Owing to the additional tunnel barriers and the related longitudinal confinement present in the device, the density of state is reduced in its off-state, while remaining comparable in its on-state, to that of a MOS transistor without barriers. The RT-FET thus features both a lower RT-limited off-current and a faster increase of the current with V_G, i.e. an improved slope characteristic, and hence an improved I_on/I_off ratio. Such improvement of the slope can happen in subthreshold regime, and therefore lead to subthreshold slope below the kT/q limit. In addition, faster increase of current and improved slope occur above threshold and lead to high thermionic on-current and significant I_on/I_off ratio improvement, even with threshold voltage below 0.2 V and supply voltage V_dd of a few hundreds of mV as critically needed for future technology nodes. Finally RT-FETs are intrinsically immune to source-drain tunneling and are therefore promising candidate for extending the roadmap below 10 nm.     

Dirty RF: A New Paradigm

The implementation challenge for new low-cost low-power wireless modem transceivers has continuously been growing with increased modem performance, bandwidth, and carrier frequency. Up to now we have been designing transceivers in a way that we are able to keep the analog (RF) problem domain widely separated from the digital signal processing design. However, with today’s deep sub-micron technology, analog impairments – “dirt effects” – are reaching a new problem level which requires a paradigm shift in the design of transceivers. Examples of these impairments are phase noise, non-linearities, I/Q imbalance, ADC impairments, etc. In the world of “Dirty RF” we assume to design digital signal processing such that we can cope with a new level of impairments, allowing lee-way in the requirements set on future RF sub-systems. This paper gives an overview of the topic and presents analytical evaluations of the performance losses due to RF impairments as well as algorithms that allow to live with imperfect RF by compensating the resulting error effects using digital baseband processing.