Alumina/NiCu Laminate under Thermal Shock up to 1000°C: I, Experimental

The mechanical behavior of an alumina/NiCu laminate under thermal shock loading was investigated. The maximum thermal shock temperature was 1000°C. The laminate architecture was the cause of a basic change in the cracking mechanisms, manifested in a dramatic increase in the mechanical residual strength over that of monolithic alumina. The laminated system was constructed by alternating alumina layers coated with copper films with nickel interlayers and joining them by a combination of liquid-state (brazing) and solid-state (diffusion) bonding. The material system was tested by water quenching square-shaped laminated specimens initially at temperatures of up to 1000°C. Three-point bending tests revealed the mechanical strength before and after thermal shock, and SEM analysis described the damage mechanisms and the extent of debonding at the alumina/NiCu interfaces.     

Failure Analysis of Modular-Block Reinforced-Soil Walls during Earthquakes

Several modular-block reinforced-soil retaining walls failed during the 1999 Ji-Ji (Chi-chi) earthquake of Taiwan. Similar walls showed distress during the 1994 Northridge, Calif., earthquake. The instability or failure of these walls offered an opportunity to validate the simplistic pseudostatic limit-equilibrium procedures. In this study, the Ta Kung Wall of the Ji-Ji earthquake is analyzed, and the Gould and Valencia Walls of the Northridge earthquake are revisited with an improved estimation of local site acceleration. The local acceleration was estimated by using simple attenuation relationships obtained through the earthquake records. The results of analysis indicate that these three walls had adequate internal stability under estimated site acceleration. The geosynthetic length was inadequate to resist compound modes of failure where the potential failure surface extends beyond the reinforced zone. The external stability was most critical in the presence of horizontal and vertical accelerations.     

Application of Differential Operator with Servo-Order Function in Model of Viscoelastic Deformation Process

The aim of the present paper is the application of a differential operator of variable order in constitutive relations for viscoelastic material. The dependence of the order function on the strain and strain rate is evaluated on the basis of known experimental results on deformation of polymeric materials. Established dependences are used for studying the vibrations of a 1-degree-of-freedom oscillator, in which the viscoelastic deformation is governed by a servo order function.     

Recursive fuzzy c-means clustering for recursive fuzzy identification of time-varying processes

In this paper we propose a new approach to on-line Takagi-Sugeno fuzzy model identification. It combines a recursive fuzzy c-means algorithm and recursive least squares. First the method is derived and than it is tested and compared on a benchmark problem of the Mackey-Glass time series with other established on-line identification methods. We showed that the developed algorithm gives a comparable degree of accuracy to other algorithms. The proposed algorithm can be used in a number of fields, including adaptive nonlinear control, model predictive control, fault detection, diagnostics and robotics. An example of identification based on a real data of the waste-water treatment process is also presented.     

Process data reconciliation in the presence of non-uniform measurement errors

The goal of flow rates reconciliation was to adjust measured values and estimate unmeasured streams so as to balance both measured and unmeasured values, identify gross errors and detect leaks and losses. Thus, data reconciliation plays a key role in the monitoring of industrial plants for the early detection of critical events which might cause environmental and economic damages, and it is,therefore, an essential component of any clean technology process. Consequently, any method that improves the accuracy of the reconstructed data by considering more realistic assumptions on the statistical nature of the data can add considerably to the overall reliability of the process. The reconciliation procedure is statistical in nature and requires adequate information on the structure of the random errors of the flow rates measured. A frequent assumption is the homoscedasticity and the independence of the errors affecting different streams. This assumption leads to efficient algorithms based on advanced linear algebra decompositions, such as QR or Singular Value Decomposition, but it frequently leads to biased estimates, especially when the values of flow rates vary over two or more orders of magnitude. The goal of this article was to show the importance of considering general heteroscedasticity when reconciling flow rates. Errors are supposed to be normally distributed according to \(\varepsilon_{\text{i}} \cong N(0,\,\sigma_{0} L_{\text{i}}^{ 2\eta } )\) , where \(L_{\text{i}}\) is the measurement of the ith flow rate and \(\theta\)  =  \(\left\{ {\theta |\sigma_{0} ,\eta } \right\}\) is a set of two parameters to be estimated along with the adjustments to the measured flow rates. Therefore, the overall variance–covariance is characterised by 3 parameters \(\sigma_{0} ,\eta\) and the correlation factor among measurement errors ρ. The algorithm here proposed is based on conditional optimality, and it carries out the whole optimisation in terms of the parameters \(\theta\) only, the unknown adjustments being expressed at each iteration as functions of \(\theta\) .     

Effects of a respite from work on burnout: Vacation relief and fade-out.

In a quasi-experiment designed to examine the relief from job stress and burnout afforded by a vacation respite, 76 clerks completed measures of job stress and burnout twice before a vacation, once during vacation, and twice after vacation. There was a decline in burnout during the vacation and a return to prevacation levels by the time of the second postvacation measure. Comparing the two prevacation measures indicated no anticipation effects. However the return to work showed gradual fade-out, as burnout returned part way toward its prevacation level by 3 days after the vacation and all the way by 3 weeks after the vacation. Women and those satisfied with their vacations experienced greater relief; however, both subsamples also experienced the quickest fade-out. The respite effect and its complete fade-out were detected among all subgroups analyzed. Burnout, relief, interpersonal stress crossover, and burnout climate at work are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personal efficacy, external locus of control, and perceived contingency of parental reinforcement among depressed, paranoid, and normal subjects.

Hypothesized that different combinations of personal efficacy and outcome expectancies (i.e., locus of control) would characterize the thought structures of normal Ss and of psychiatric patients suffering from distinctly different disorders. 26 normal (mean age 30.1 yrs), 15 depressed, and 22 paranoid Ss (mean age of patients 34.5 yrs) completed scales that measured beliefs in personal efficacy, beliefs that outcomes are controlled either by chance or by powerful others, and perceived contingency of parental reinforcement. Findings show that normals judged themselves to be more efficacious than did psychiatric Ss, depressives expected outcomes to be controlled by chance, and paranoids expected outcomes to be under the control of powerful others. Among the normals, outcome expectancies were strongly associated with personal efficacy, but among the patients, these beliefs were unrelated. Depressives and paranoids equally reported more noncontingent parental reinforcement than did normals. Perceived contingency of parental reinforcement was predictive of outcome expectancies but not of personal efficacy. Data suggest that low personal efficacy may be a distinguishing characteristic of all psychiatric patients, whereas outcome expectancies may determine the specific nature of the psychiatric disorder. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Finite-Element Simulations of Full-Scale Modular-Block Reinforced Soil Retaining Walls under Earthquake Loading

A finite-element procedure was used to simulate the dynamic behavior of four full-scale reinforced soil retaining walls subjected to earthquake loading. The experiments were conducted at a maximum horizontal acceleration of over 0.8 g, with two walls subjected to only horizontal accelerations and two other walls under simultaneous horizontal and vertical accelerations. The analyzes were conducted using advanced soil and geosynthetic models that were capable of simulating behavior under both monotonic and cyclic loadings. The soil behavior was modeled using a unified general plasticity model, which was developed based on the critical state concept and that considered the stress level effects over a wide range of densities using a single set of parameters. The geosynthetic model was based on the bounding surface concept and it considered the S-shape load-strain behavior of polymeric geogrids. In this paper, the calibrations of the models and details of finite-element analysis are presented. The time response of horizontal and vertical accelerations obtained from the analyses, as well as wall deformations and tensile force in geogrids, were compared with the experimental results. The comparisons showed that the finite-element results rendered satisfactory agreement with the shake table test results.     

Resultant Force of Lateral Earth Pressure in Unstable Slopes

Traditionally, resultant force of lateral earth pressure serves as the basis for design of nearly vertical walls. Conversely, slopes are designed to be internally stable using a factor of safety approach. However, with the availability of heavy facing elements such as gabions, steep slopes are increasingly being constructed. Steep slopes are considered to be unstable unless supported; that is, such slopes require facings to resist lateral earth pressure. Extending Coulomb’s formulation to such slopes may not be conservative as a planar slip surface may not be critical. Presented are the results of a formulation to find the resultant lateral force which utilizes a log spiral failure mechanism. Unlike Caquot and Kerisel or Coulomb, the soil-facing interface friction is assumed to act on segments of vertical surface only, thus replicating the geometry of stacked rectangular facing units. Given the batter, the backslope, the height, the interface friction, and the unit weight and design friction angle of the backfill, one can quickly determine the corresponding lateral earth pressure coefficient. Formulation assuming the interface friction is acting on an imaginary surface inclined at the batter angle, essentially equivalent to Coulomb and Caquot and Kerisel, is also presented. Its results show that for batters up to 20°, the common approach of using the Coulomb method, including the assumed interface friction direction to coincide with the batter, yields results that are quite close to those stemming from the log spiral analysis. Hence, use of Coulomb’s analysis for such small batters is reasonable as its formulation is simple. However, the lateral resultant is grossly underestimated for larger batters, especially when Coulomb analysis is used.     

Electronic structure and self-assembly of cross-linked semiconductor nanocrystal arrays

We studied the electronic level structure of assemblies of InAs quantum dots and CdSe nanorods cross-linked by 1,4-phenylenediamine molecules using scanning tunneling spectroscopy. We found that the bandgap in these arrays is reduced with respect to the corresponding ligand-capped nanocrystal arrays. In addition, a pronounced sub-gap spectral structure commonly appeared which can be attributed to unpassivated nanocrystal surface states or associated with linker-molecule-related levels. The exchange of the ligands by the linker molecules also affected the structural array properties. Most significantly, clusters of close-packed standing CdSe nanorods were formed.