Rogue components: their effect and control using logical analysis of data

There is a small subset of any repairable component population that can develop a failure mode outside the scope of the standard repair and overhaul procedures, which makes them “rogue”. When this happens, a Darwinian-like “natural selection” phenomenon ensures that they will be placed in the most disadvantageous position in the asset management program, negatively affecting multiple aspects of the operational and maintenance organizations. Rogue components have long plagued the airline industry and created havoc in their asset management programs. In this paper, we describe how these rogues develop, outline the natural selection process that leads to their hampering the asset management program, and examine some of the negative impacts that ensue. Then we propose a Condition based maintenance approach to control the development of these components. We explore the use of a supervised learning data mining technique called Logical analysis of data (LAD) in CBM for the purpose of detecting rogues within a population of repairable components. We apply the resulting LAD based decision model on an inventory of turbo compressors belonging to an airline fleet. Finally, we evaluate the applicability of LAD to the rogue component detection problem and review its efficiency as a decision model for this type of problem.     

Analytical solutions to a network of standard linear solids

Various viscoelastic models, such as the standard linear solid, Maxwell model, and Kelvin–Voigt model, are frequently used to describe the behavior of biological materials from single cells to tissues. These models are expressed mathematically as simple differential equations, called constitutive equations, which relate the applied force (stress) to the resulting deformation (strain) of the material. Networks of these models, representing materials with heterogeneous mechanical properties, are described by systems of constitutive equations. We prove that the eigenvalues associated with such systems are all nonpositive real numbers, find bounds for them, and indicate how they can be estimated quickly and accurately. We then give formulas for the analytical solutions of the system of equations.     

Synthesis of ‘ready-to-adsorb’ polymeric nanoshells for magnetic iron oxide nanoparticles via atom transfer radical polymerization

Polymer-magnetite nanoparticle complexes that respond to both magnetic fields and to temperature have been demonstrated. Novel alkyl halide-functional bis(diethylphosphonate) esters were prepared and utilized as initiators for polymerizing N-isopropylacrylamide by controlled atom transfer radical polymerization. The phosphonate esters were removed after polymerization to afford poly(N-isopropylacrylamide) with a bis(phosphonic acid) moiety precisely placed at one terminus. The bis(phosphonic acid) endgroups were adsorbed onto magnetite nanoparticles to yield nanoscale complexes that were stable against any polymer desorption and that were colloidally-stable in physiological media. Thus, the bis(phosphonate) endgroup provides a robust anchoring moiety onto the magnetite. Hydrodynamic sizes of the complexes were predicted with a density distribution model and using the measured sizes of the magnetite cores. Good agreement between the measured and predicted hydrodynamic sizes suggested that the complexes were primarily discrete, non-agglomerated nanoparticles. The complexes exhibited thermosensitive aggregation behavior near the lower critical solution temperature of the poly(N-isopropylacrylamide) component.     

Obesity as a risk factor for certain types of cancer

Summary and Conclusions In conclusion, obesity has been associated with increased risk for a number of different types of cancer. The evidence has been most consistent for endometrial cancer, breast cancer in postmenopausal women, and renal cell cancer. More variable results have been reported for colorectal, prostate and pancreatic cancer. Possible mechanisms by which obesity may influence cancer risk include alteration in hormonal patterns, including sex hormones and insulin, and factors such as the distribution of body fat and changes in adiposity at different ages. The increasing prevalence of obesity in many parts of the world emphasizes the importance of learning more about the relationship between obesity and cancer and the mechanisms involved in their interaction. This paper was prepared as one of the background documents for the WHO Consultation on Obesity (Geneva, Switzerland, 3–5 June 1997). For further details, please see the report of the Consultation, Obesity: preventing and managing the global epidemic (WHO/NUT/NCD/97.2).     

Therelations between cluster indexes of risk and promotion and the problem behaviors of 6- and 7- year old children from economically disadvantaged families.

This study examined the relations between alternative explanations of poverty cofactors and promotion processes and teacher reports of the problem behaviors of 6- and 7-yr old children from economically disadvantaged families (N?=?159). The results showed that single index representations of risk and promotion variables predicted child aggressive behaviors but not child anxious/depressed behaviors. An addictive model of individual risk indicators performed similarly. Similar indexes representing clusters of parent adjustment variables and family instability variables, however, differentially predicted aggressive and anxious/depressed behaviors, respectively. The results suggest the importance of promotion processes and representing environmental adversity at varying levels of specificity for children from economically disadvantaged families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Compact modeling of 0.35 μm SOI CMOS technology node for 4 K DC operation using Verilog-A

Compact modeling of MOSFETs from a 0.35 μm SOI technology node operating at 4 K is presented. The Verilog-A language is used to modify device equations for BSIM models and more accurately reproduce measured DC behavior, which is not possible with the standard BSIM model set. The model presented exhibits convergent behavior and is shown to be experimentally accurate at 4 K. No design tool currently in place exhibits convergence and/or accuracy over this range. The Verilog-A approach also allows the embedding of nonlinear length, width and bias effects into BSIM calculated curves beyond those that can be achieved by the use of different BSIM parameter sets. Nonlinear dependences are necessary to capture effects particular to 4 K behavior, such as current kinks. The 4 K DC behavior is reproduced well by the compact model and the model seamlessly evolves during simulation of circuits and systems as the simulator encounters SOI MOSFETs with different lengths and widths. The incorporation of various length/width and bias dependent effects into one Verilog-A/BSIM4 library, therefore, produces one model for all sets of devices called up in a given product design kit (PDK) for this technology node.