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The current standards for evaluating corrosion during salt spray tests rely on the visual analysis of the specimens, and this may be a limitation when higher resolution quantitative outputs are desired. In this work, computational image analysis was used to measure the area affected by corrosion during salt spray tests with aluminum alloy, copper, carbon steel and galvanized steel plates. The software ImageJ was used to select and measure the corroded areas differentiating the corrosion products from the metals uncorroded surfaces according to their different colors. With ten measurements for each selected exposure time, a 95 % confidence interval was calculated for each material and time of exposure, giving an indication of the precision of the estimated corroded area. These data were compared with a visual inspection carried out by an experienced technician. The results indicate that computational image analysis may be a powerful tool to obtain higher resolution in the results interpretation in comparison with the standard visual analysis

In this investigation, a design of experiments analysis of distortion for a typical manufacturing process involving pre-straightening, cold drawing, and induction hardening of AISI 1045 cylindrical steel bars was carried out. A careful characterization of the material, including residual stress states and geometrical changes, was done for the different manufacturing steps. In order to identify effects and correlations on distortion behavior, the investigated variables included the batch influence, the combined drawing process itself with two different drawing angles and two different polishing and straightening (P.S.) angles, a stress relief treatment which was applied to a part of the samples, and finally induction hardening with two different surface hardening depths. Main and statistically significant effects on the distortion of the induction-hardened samples were found to be in this order: first, the interaction between the drawing angle and batch, then the interaction between drawing angles, and finally drawing angle and induction hardened layer. It was also found that the distortion potentials are transmitted from the drawing process to further manufacturing steps and, consequently, from one production site to the next.

This paper presents a low-cost analog test system with diagnosis capabilities. The tester is able to detect faults in any linear circuit by learning a reference circuit behavior in a first step, and comparing this behavior against the output of the circuit under test in a second step. For a faulty circuit, a third step takes place to locate the fault. The diagnosis method consists on injecting probable faults in a mathematical model of the circuit, and later comparing its output with the output of the real faulty circuit. This system has been successfully applied to a case study, a biquad filter. Soft, large, and hard deviations on components, as well as faults in operational amplifiers, were considered. Experimental results have proven the feasibility and efficiency of the proposed test and diagnosis system.

With the increasing power density in integrated systems resulting from scaling down, the occurrence of field failures due to overheating has considerably increased. Faulty operation can be prevented by on-line temperature monitoring. This paper deals with questions of on-line temperature monitoring in safety-critical systems. First the possible temperature sensors are reviewed and basic principles of self-checking systems including such sensors are detailed, then a new temperature sensor cell with extremely good parameters designed especially for DfTT applications is presented. The basic questions of integrating thermal sensors into self-checking systems are also discussed.

The properties of weakly bonded soil have been studied experimentally, mainly by an extension of recent work on artificial bonded sand. Higher stresses were used to fully examine yield of this soil when at denser states. Triaxial equipment applying confining pressures of 3.5 MPa and a belt for measuring radial strain on triaxial soil samples were developed. The influence of saturation procedures on test results was investigated. A new loading arrangement has been used and comparative studies carried out to evaluate its influence. The new arrangement improves the stress distribution in the sample and the quality of the conventional strain measurements taken platen to platen. It also reduces premature failure of tbe sample due to non-uniform stresses. Two natural materiais with some degree of cementation were also tested: the Corinth marl (a soft carbonaceous rock from Greece) and the Chemususu Dam soil (a red lateritic soil from Kenya). Both materiais have similar characteristics to the artificial soil when tested in triaxial compression. The bonded soils have shown a characteristic variation of stiffness with confining pressure. As the pressure is increased the secant initial stiffness increases initially but, at some treshold value of confining stress, show stabilization or even a drop on its absolute value, depending on the initial void ratio and the strength of the bonding. The bonded soils have a curved yield locus which is coincident with the failure envelope at low stresses. The failure envelope in the low stress region is dependent of the stress path, being lower for conventional drained compression tests.