A short-range, high-resolution millimeter-wave surface movement radar

Today’s Air (and Airport traffic) management needs an advanced surveillance function for the airport’s surface. Among the different sensors to be integrated for this function just the surface movement radar is able to detect the presence, and determine the position, of non co-operating targets. Present-day smr’s are considered aged and inadequate. In this paper we propose a novel short range radar, operating at frequencies around 95 GHz, to be used in a distributed surface surveillance system. Its main characteristics and the trade-off considerations involved in its design are discussed.     

Obtaining hydrocarbons from ethanol over iron-modified ZSM-5 zeolites

The search for new energy sources has impulsed hydrocarbon production from methanol and ethanol over ZSM-5 zeolites. Iron incorporation by different methods has led to a variety of chemical applications. Thus, hydrocarbon production from ethanol was studied over a ZSM-5 zeolite modified by ion exchange and impregnation with iron. XRD, FTIR, TPR, nitrogen adsorption, Mössbauer and photoacoustic spectroscopies were used for the samples characterization. The highest yield of liquid hydrocarbons was obtained with the low iron-exchanged zeolite, especially co-feeding hydrogen. The calcination procedure led to a migration of the iron species, probably forming iron oxide particles.     

On complete stability of linear and quadratic programming neural networks

The paper addresses complete stability (CS) of the important class of neural networks to solve linear and quadratic programming problems introduced by Kennedy and Chua (IEEE Trans. Circuits Syst., 1988; 35 : 554). By CS it is meant that each trajectory converges to a stationary state, i.e. an equilibrium point of the neural network. It is shown that the neural networks in (IEEE Trans. Circuits Syst., 1988; 35 : 554) enjoy the property of CS even in the most general case where there are infinite non‐isolated equilibrium points. This result, which is proved by exploiting a new method to analyse CS (Int. J. Bifurcation Chaos 2001; 11 : 655), extends the stability analysis by Kennedy and Chua (IEEE Trans. Circuits Syst., 1988; 35 : 554) to situations of interest where the optimization problems have infinite solutions. Copyright © 2002 John Wiley & Sons, Ltd.     

Executable specifications with data-flow diagrams

Specifications of information systems applications are often based on the use of entity-relationship (ER) and data-flow diagrams (DFD), which cover, respectively, the conceptual modelling of data and funtions. This paper introduces VLP: an executable visual language for formal specifications and prototyping which integrates ER and DFD diagrams in a semantically rigorous and clear way. Unlike existing commercial products (so-called CASE tools), which can support good-quality documentation, simple forms of consistency checking and bookkeeping, VLP also supports executable specifications, which provide a prototype of the desired application. After reviewing the principles of VLP, the paper outlines the structure of the ECASET environment in which VLP is embedded. In particular, it shows how the environment supports the stepwise derivation of specifications, from informal to formal, and how it supports specification-in-the-large.     

Analysis of a PLL System as Analog Processor in CW Doppler Flowmeters

In this paper a phase-locked loop (PLL) system is analyzed in order to evaluate its performance for estimating the average frequency of an input spectrum made up by Ndiscrete components allocated in a frequency interval B. The system was studied first in the simplified case that the phase comparator has a linear characteristic. Next, a computer-aided simulation of the PLL system was performed taking into account the nonlinear characteristic of the phase comparator, assuming that the input spectral components have mutual random phase in (-?, + ?) interval and amplitudes with a distribution either uniform or obtained from a particular parabolic velocity profiles.     

Lack of pharmacological effect of subcutaneous octreotide in an insulin-dependent diabetic patient: reversal after mixing with aprotinin

OBJECTIVE: To evaluate the outcome of late probing in a mixed Asian children population with congenital nasolacrimal duct obstruction (CNLDO) and whether probing was associated with an increased risk of infection. METHOD: A retrospective clinical study was conducted. A clinical diagnosis of CNLDO was defined in an infant who presented with a history of tearing and/or eye discharge up to 1 year of age with no other accompanying ocular pathology. All patients with a presumed diagnosis of CNLDO who had probing after 12 months of age were included in our study. Prior to probing, most patients had a trial of conservative treatment with massage and/or topical antibiotics. Intra-operative patency of probing was determined when metal to metal contact of the probe and forceps was achieved and/or when fluorescein dye was recovered from the nose after syringing. Successful probing was defined as a resolution of symptoms within 1 month after probing. RESULTS: Seventeen patients involving 19 eyes fulfilled our inclusion criteria for this study. Fourteen (82%) infants were Chinese, two Malays (12%) and the remaining one Indian (6%). There were 10 males (59%) and 7 females (41%) and the mean age at probing was 2.2 years (range, 14 months to 5 years 6 months). The subjects were followed-up post-operatively for a mean duration of 21.2 months (range, 2 months to 8 years). Successful probing in our series was 89.5% (17/19 eyes). Of the two eyes with persistent tearing, one resolved with massage about 9 months after the unsuccessful probing; the other was referred to the oculoplastic service for further management. CONCLUSION: Late probing after 13 months old appears to be an effective approach in the management of CNLDO in Asian infants.     

Tropical rainfall drop-size distribution

Based on disdrometer measurements carried out in Brazil, this paper discusses the problem of rainfall drop-size distribution in tropical areas and its effect on radiowave propagation at frequencies above 10 GHz. A comparison between Laws and Parsons and lognormal models is made. In spite of the best fit to the experimental data shown by the lognormal distribution, in the range from 10 to 20 GHz there is no significant difference between the two models. However, as the frequency increases this difference becomes larger and may be an important source of error in the design of both terrestrial and satellite links in low-latitude regions. Similar results from Nigeria (Africa) are also taken into account.     

Smile: a computer program for partitioning of programmed logic arrays

This paper presents a new approach to optimal topological design of PLAs (programmed logic arrays). In particular we address the array partitioning problem and the implementation of partitioned arrays as block folded or parallel connected PLAs. We present a graph theoretic interpretation of the problem and an efficient heuristic algorithm. A computer program, Smile, is described and experimental results are reported.