Indirect test of M-S circuits using multiple specification band guarding

Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information that correlates with circuit performances. In this work, a multiple specification band guarding technique is proposed as a method to achieve a test target of misclassified circuits. The acceptance/rejection test regions are encoded using octrees in the measurement space, where the band guarding factors precisely tune the test decision boundary according to the required test yield targets. The generated octree data structure serves to cluster the forthcoming circuits in the production testing phase by solely relying on indirect measurements. The combined use of octree based encoding and multiple specification band guarding makes the testing procedure fast, efficient and highly tunable. The proposed band guarding methodology has been applied to test a band-pass Butterworth filter under parametric variations. Promising simulation results are reported showing remarkable improvements when the multiple specification band guarding criterion is used.     

Variation in electric resistivity in metastable alloys during thermomechanical loading: Effects of temperature,elasticity, plasticity and phase transformation

301L metastable stainless steel is a ductile material in which there is strong coupling between plasticity and phase transformation, leading to strongly non-linear thermomechanical behaviour. To determine phase transformation kinetics, isothermal tensile tests at different temperatures were carried out and in situ voltage (electric resistance) was measured. We then chose an appropriate post-processing method based on observed voltage using strain and temperature. It was thus possible to determine the effect of temperature, elasticity, plasticity and phase transformation on the electric resistivity of the studied material. After identifying the effect of each strain mechanism, a volume phase fraction determination method based on electric resistivity variation was developed and used to determine the kinetics of phase transformation. Finally, we compared our results with those of two classic methods: the neutron diffraction method and the magnetic method.     

Incipient Boiling on Exponentially Heated Surfaces

Calculations have been performed on the asymptotic angular neutron flux, critical thickness and extrapolation distance in the axial direction for a cylindrical system of finite length. Neutrons are assumed to be monoenergetic. Applying the finite Laplace transformation in the axial direction and buckling approximation in the radial, we find a solution of the transport equation that satisfies the boundary conditions of no incoming neutron and symmetry. This method is an extension of Kobayashi's Laplace transform method for slab problem, and may easily be applied to other geometries. For a rectangular prism system, numerical results based on our method are compared with results from P₃-approximation.     

Boundary detection of internal defect based on discontinuity of second-order gradient of out-of-plane displacement in phase-shifting digital speckle pattern interferometry

A new method for detecting the boundary of an internal defect is proposed in this paper. The proposed method can be used in phase-shifting digital speckle pattern interferometry to detect accurately the boundary of an internal defect based on discontinuity of the second-order gradient of out-of-plane displacement in the direction perpendicular to the defect boundary. Both theoretical analysis and experimental result are presented in this paper.     

Confined relaxation dynamics in long range ordered polyesters with comb-like architecture

The cooperative relaxation dynamics of methylene units in self-assembled amorphous alkyl nanodomains with typical dimensions in the range 5–20 Å is studied in a series of poly(1,4-phenylene-2,5-n-dialkyloxy terephthalate)s (PPAOTs) with C = 6–12 alkyl carbons per side chain. These comb-like polymers are long range ordered on the nanoscale since domains where main chains are stacked in a crystal-like manner alternate with alkyl nanodomains formed by aggregated side chains. Dynamic mechanical data for the investigated PPAOTs show polyethylene-like glass transitions α_PE which are similar to those for many other polymer series with comb-like architecture containing long alkyl side groups. Hence, self-assembled PPAOTs are excellent model systems for studies focusing on a detailed understanding of the influence of (i) alkyl nanodomain size, (ii) average volume per CH₂ unit and (iii) number of alkyl groups per interfacial area on the cooperative dynamics of methylene units seen as α_PE process. Structural parameters as obtained from X-ray diffraction experiments allow to deduce quantitative information about these influencing factors. The results are compared with those for regio-regular poly(3-alkyl thiophenes) with similar molecular architecture. The comparison shows that important features of the α_PE process within amorphous alkyl nanodomains are main chain independent even in case of long-range ordered polymers with quite different main chain packing. It is concluded that the alkyl nanodomain size is the most important factor determining the α_PE dynamics of the methylene units. Main chain dependent aspects like average volume per CH₂ unit and interfacial constraints do only weakly influence the relaxation behavior within the alkyl nanodomains.     

A model to estimate the path loss in areas with foliage of trees

This paper presents an empirical model to predict attenuation in forest environments considering parameters related to vegetation. Typically, environmental parameters are only included in theoretical models, but they are more difficult to apply. The developed model uses tree density, average tree canopy diameter and foliage density as input parameters. The foliage density is very difficult to determine since it depends on the characteristics of trees. A simple metric of this parameter was obtained by measuring the background light silhouetted by the canopy. The model was developed with measurements obtained in different forest environments for two frequencies within the UHF band (Ultra High Frequency). A procedure was also applied to extend the operating frequency range of the model.     

On monitoring the process mean of autocorrelated observations with measurement errors using the w-of-w runs-rules scheme

Runs-rules have been widely used since the 1950s in industrial and nonindustrial process monitoring applications to improve the performance of basic and other traditional monitoring schemes. However, none of the studies on runs-rules have accounted for a process with a combined effect of measurement errors and autocorrelation. Hence, in this paper, the use of the w-of-w runs-rules to improve the performance of the Shewhart $\overline{X}$ scheme using an additive model with a constant variance and a first-order autoregressive model is proposed. To reduce the combined negative effect of measurement errors and autocorrelation, we implement a sampling strategy based on rational subgroups in which (a) multiple measurements per item are taken (instead of a standard single measurement) and (b) non-neighboring observations are gathered. Moreover, the latter sampling strategy is incorporated into the values of probability elements of a Markov chain matrix which is used to derive some closed-form expressions for the zero- and steady-state run-length distribution. The main finding of this study is that, with respect to some overall performance measures, the proposed scheme outperforms the existing Shewhart $\overline{X}$ scheme by a significant margin. A real-life example is used to illustrate the practical implementation of the proposed scheme.     

Coastal trapped waves in the southern Caspian Sea

Previous studies reported coastal trapped waves (CTWs) in the Caspian Sea (CS). This study deals with the generation mechanisms, the temporal and spatial variability of CTWs in this area, and their transformations during propagation from the origin to the destination using recent measurements and high-resolution numerical simulations. CTWs are observed at all stations with periods of 2–6 days after northerly storms. The Absheron Peninsula, old Sefidrud delta, and Nur coasts were identified as the CTWs prone regions. The generation of CTWs in these locations was confirmed using numerical experiments. The propagation away from the generating location of CTWs was analyzed using a representative real wind storm. In the west part of the CS, the generation mechanism of CTWs is mainly similar to the barotropic Kelvin waves; in contrast, it is similar to the continental shelf waves in the southern shelves. The results can be used to study the contribution of generated CTWs to the transport of sediment and biological materials in all large lakes.     

Analysis of indoor particles and gases and their evolution with natural ventilation

The air composition and reactivity from outdoor and indoor mixing field campaign was conducted to investigate the impacts of natural ventilation (ie, window opening and closing) on indoor air quality. In this study, a thermal desorption aerosol gas chromatograph (TAG) obtained measurements of indoor particle‐ and gas‐phase semi‐ and intermediately volatile organic compounds both inside and outside a single‐family test home. Together with measurements from a suite of instruments, we use TAG data to evaluate changes in indoor particles and gases at three natural ventilation periods. Positive matrix factorization was performed on TAG and adsorbent tube data to explore five distinct chemical and physical processes occurring in the indoor environment. Outdoor‐to‐indoor transport is observed for sulfate, isoprene epoxydiols, polycyclic aromatic hydrocarbons, and heavy alkanes. Dilution of indoor species is observed for volatile, non‐reactive species including methylcyclohexane and decamethylcyclopentasiloxane. Window opening drives enhanced emissions of semi‐ and intermediately volatile species including TXIB, DEET, diethyl phthalate, and carvone from indoor surfaces. Formation via enhanced oxidation was observed for nonanal and 2‐decanone when outdoor oxidants entered the home. Finally, oxidative depletion of gas‐phase terpenes (eg, limonene and α‐pinene) was anticipated but not observed due to limited measurement resolution and dynamically changing conditions.