Testing from a stochastic timed system with a fault model

In this paper we present a method for testing a system against a non-deterministic stochastic finite state machine. As usual, we assume that the functional behaviour of the system under test (SUT) is deterministic but we allow the timing to be non-deterministic. We extend the state counting method of deriving tests, adapting it to the presence of temporal requirements represented by means of random variables. The notion of conformance is introduced using an implementation relation considering temporal aspects and the limitations imposed by a black-box framework. We propose a new group of implementation relations and an algorithm for generating a test suite that determines the conformance of a deterministic SUT with respect to a non-deterministic specification. We show how previous work on testing from stochastic systems can be encoded into the framework presented in this paper as an instantiation of our parameterized implementation relation. In this setting, we use a notion of conformance up to a given confidence level.     

Slips and falls in a cold climate: underfoot surface, footwear design and worker preferences for preventive measures

Slips and falls and associated outdoor injuries are prevalent in cold climates. The objectives of this field investigation were to describe the consequences of slips and falls on ice and snow and the associated injuries, to assess the risks of various icy and snowy surfaces, to identify design needs of footwear, and to ascertain preventive measure preferences of outdoor workers. The organizations investigated were a newspaper delivery service, a military regiment, mining and construction industries. The results showed that fall events occur most frequently on ice covered with snow. This is due to the difficulty of perceiving hidden risks in order to adjust gait strategies. The professional footwear provided does not provide enough protection against slips and falls. Slip resistant properties are ranked as one of the top requirements by the users. Their most preferred preventive measures are footwear with anti-slip properties and the application of anti-slip materials, such as sand or salt.     

Nonlinear vehicle side-slip estimation with friction adaptation

A nonlinear observer for estimation of the longitudinal velocity, lateral velocity, and yaw rate of a vehicle, designed for the purpose of vehicle side-slip estimation, is modified and extended in order to work for different road surface conditions. The observer relies on a road-tire friction model and is therefore sensitive to changes in the adhesion characteristics of the road surface. The friction model is parametrized with a single friction parameter, and an update law is designed. The adaptive observer is proven to be uniformly globally asymptotically stable and uniformly locally exponentially stable under a persistency-of-excitation condition and a set of technical assumptions, using results related to Matrosov's theorem. The observer is tested on recorded data from two test vehicles and shows good results on a range of road surfaces.     

Study on the electrical conductivity and morphology of porous polypyrrole layers prepared electrochemically in the presence of pyridinium chlorochromate

The electrical conductivity and morphology of thick (up to 3 mm) porous polypyrrole (PPy) layers produced electrochemically from pyrrole in acetonitrile (ACN) solutions have been studied. The electrical conductivity of pressed porous layers ranges from 1 to 10 Scm^–1, which is about one order of magnitude less than that in films which were prepared under similar conditions but without PnClCr. Analysis of the temperature dependence of conductivity has confirmed the major role of hopping in relation to tunnelling in charge transport inside the PPy layers even at lower temperatures. Scanning electron microscopy (SEM) showed a globular structure, which is different from the usual cauliflower-like structure of PPy films prepared without any oxidizing agent. Globular particles of about 1–3 m diameter have been found under a thin smooth crust on the electrode side of the sample. Globular particles form linked chain-like or larger round formations poorly filling the space. Closely packed fibrils of about 20 nm diameter and over 100 nm in length were found inside the aggregates.     

An assessment of simple referee methods for the prediction of lean in pig carcasses

A study was carried out in which carcass characteristics of 36 gilts were evaluated: 18 originated from the Hungarian 'Hungahyb' cross-breed, another 18, with undefined genetic background, from small private household plots. Two, rather simple substitute reference methods, called referee methods, were evaluated: measurement of carcass weight without skin and subcutaneous fat ('meat + bone'), and measurement of carcass weight without skin, subcutaneous fat and bone ('boneless meat'). Both methods gave a rather close relationship with the Kulmbach reference lean; however, removal of bone had presumably a beneficial effect on stability of prediction. The importance of preliminary information in quantitative form, giving a theoretical background for prediction equations, was presented as an example. Simple material balances could be formulated between reference lean and 'meat + bone' or 'boneless meat' content. Such material balances could not be set up with the indirect, rapid surrogate methods using mainly linear measurements (e.g. fat and muscle thickness, etc.) For this reason, as several other publications demonstrated, these latter methods seem to be more susceptible to bias than the referee methods. By determining the lipid content of the homogenised 'boneless meat' component, a 'lean' value adjusted to 3% fat content could be calculated from data which was compared to the dissected reference lean standardised also to contain 3% fat. These relationships, for several reasons discussed in this paper, were not as close as expected. So, further studies are needed to reveal these discrepancies.     

The δ-Al2O3 (Saffil) fibre degradation during infiltration with MgLi alloy

The chemical and phase transformations of -Al₂O₃ (Saffil) fibres during their infiltration with Mg-8 wt% Li were studied by scanning and transmission electron microscopy, Auger electron spectroscopy, secondary ion mass spectrometry and X-ray diffraction methods. The infiltration experiments were carried out in autoclave under argon pressure at temperatures of 883–908 K and contact times of 4–30 s as well as at 918 K/420 s. During the course of infiltration, lithium penetrates the Saffil fibres and this process is accompanied by the gradual transformation of the tetragonal -Al₂O₃ lattice towards the cubic spinel LiAl₅O₈ compound, where part of the Li⁺ ions is probably substituted by Mg²⁺ No remarkable interfacial zone at the fibre/matrix interface was observed; however, the Saffil fibres became brittle which had been manifested by the occurrence of fragmentation on the metallographically treated fibre cross-sections. The tensile strength (maximum 220 MPa) of the corresponding metal matrix composite clearly decreased with increased infiltration time.     

The necessity of conducting to the end the activities of vector control in the onchocerciasis control program in west Africa: recall of the stakes and proposal of a minimum budget for the period 1998-2002

After a brief presentation of the Onchocerciasis Control Programme in West Africa (OCP), the authors realize the health and socioeconomic consequences that could follow a cessation of larvicide treatment before 2002 in the south-eastern and western extensions of the Programme. Taking into account that OCP activities are theoretically supported until 1997, but aware of financial constraints that will probably increase from now to 2002, this paper proposes an a minima estimation of the residual vector control activities for a "phasing out" spread out for five years (1998-2002). These estimations essentially concern the larvicide coverage, the insecticides used, the entomological surveillance, the logistical support and their financial aspects. As far as 48 U.S. $ million amount for 5 years are concerned, the budget allocated for vector control activities should not exceed the third of the global amount allocated to OCP for the actual fourth financial phase of the Programme (1992-1997).     

Valence band density of states of small cobalt particles on Si(111) substrate

Small Co particles were prepared by sputter etching of a 4–5 nm thick island-like Co film deposited on Si(111) substrate. The density of states (DOS) of the valence band was measured by means of ultraviolet photoemission (UPS) during the sputter etching to monitor the formation of small Co particles. It was found that at a given thickness of the Co island the Fermi level was shifted by 1.8-1.9 eV toward higher binding energy and theDOS decreased or no states were detectable at the Fermi level. This effect was explained by the formation of small Co particles with electronic structure which is significantly different from that of the bulk Co.     

Comparison of some components of pigs kept in natural (free-range) and large-scale conditions

A new pig genotype of Hungarian Large White (75%) × Mangalica (pig with curly bristles, 25%) was used in the experiments. The experimental group was kept in a farming system under strictly natural circumstances until a body weight of 120 kg was attained. Neither antibiotics nor yield-increasing hormones were given to this group. The control group was kept in the usual large-scale farming conditions until body weight of 120 kg was attained. In most cases, protein, zinc, and copper levels and, in some cases, iron levels were significantly higher in some major cuts (neck-end (Boston-butt), loin, ham) of the 'free-range' pigs (n = 12) in comparison with the control animals kept in large-scale farming conditions. There was, on average, 15% less cholesterol in the muscles and 30% less cholesterol in the liver and less linoleic acid in all tissues of 'free-range' pigs than in the control group. There was less fat, but the amount of thiamin and riboflavin in the liver of the naturally kept pigs was twice that in the controls. In respect of TBA-reactive compounds, there were no significant differences between the two groups, but superoxide dismutase (SOD) showed significantly higher activities in all cuts from pigs kept in a large-scale farming system. This may be the effect of a higher level of linoleic acid in the fat.