Fast, portable application mirroring

Previous implementations of an application mirror-a tool that lets two computers interactively share an application-have required hardware modifications, been restricted to one platform, and suffered from slow data throughput. The authors overcome these drawbacks by transmitting only those events that affect a shared application's status     

Oxidation characteristics of Ti-25Al-10Nb-3V-1Mo

Static oxidation kinetics of Ti-25Al-10Nb-3V-1Mo (atomic percent) were investigated in air over the temperature range of 650–1000°C using thermogravimetric analysis. The oxidation kinetics were complex at all exposure temperatures and displayed up to two distinct stages of parabolic oxidation. Breakaway oxidation occurred after long exposure times at high temperatures. Oxidation products were determined using x-ray diffraction techniques, electron microprobe analysis, and energy dispersive x-ray analysis. Oxide scale morphology was examined using scanning electron microscopy of the surfaces and cross-sections of oxidation specimens. The oxides during the parabolic stages were compact and multilayered, consisting primarily of TiO₂ doped with Nb, a top layer of Al₂O₃ and a thin bottom layer of TiN. The transition between the first and second parabolic stage is linked to the formation of a TiAl layer at the oxide-metal interface. Porosity also formed in the TiO₂ layer during the second stage, causing degradation of the oxide and breakaway oxidation.     

Accelerated Life Testing (ALT) Design Based on Computational Reliability Analysis

Accelerated life testing (ALT) design is usually performed based on assumptions of life distributions, stress–life relationship, and empirical reliability models. Time‐dependent reliability analysis on the other hand seeks to predict product and system life distribution based on physics‐informed simulation models. This paper proposes an ALT design framework that takes advantages of both types of analyses. For a given testing plan, the corresponding life distributions under different stress levels are estimated based on time‐dependent reliability analysis. Because both aleatory and epistemic uncertainty sources are involved in the reliability analysis, ALT data is used in this paper to update the epistemic uncertainty using Bayesian statistics. The variance of reliability estimation at the nominal stress level is then estimated based on the updated time‐dependent reliability analysis model. A design optimization model is formulated to minimize the overall expected testing cost with constraint on confidence of variance of the reliability estimate. Computational effort for solving the optimization model is minimized in three directions: (i) efficient time‐dependent reliability analysis method; (ii) a surrogate model is constructed for time‐dependent reliability under different stress levels; and (iii) the ALT design optimization model is decoupled into a deterministic design optimization model and a probabilistic analysis model. A cantilever beam and a helicopter rotor hub are used to demonstrate the proposed method. The results show the effectiveness of the proposed ALT design optimization model. Copyright © 2015 John Wiley & Sons, Ltd.     

Handling of Dependence in Dempster–Shafer Theory

Dempster's rule of combination can only be used when the bodies of evidence are assumed to be independent. However, such an assumption is often unrealistic. This paper proposes a systematic approach to handle dependence in evidence theory. It includes both the representation of dependence among information sources and the aggregation of the dependent evidence. For the representation of the dependence, the proposed methodology is able to capture both inner dependence (i.e., dependence among features of a system) and outer dependence (i.e., dependence among the evidence sources during the information propagating and evaluating process). We suggest dealing with the inner dependence by applying the analytic network process model, and modeling the outer dependence based on the intersection situations of the identified influencing factors. Then for the combination of dependent evidence, the strategy is to use discounting aggregation where the discounting coefficients are related to the degree of both outer and inner dependence. The discounting operator helps reduce the duplicate calculations in the fusion of dependent evidence and relax the assumption of independence when using Dempster's rule. A case study of transportation project evaluation is used to illustrate the proposed methodology.     

A surrogate modeling approach for reliability analysis of a multidisciplinary system with spatio-temporal output

Reliability analysis of a multidisciplinary system is computationally intensive due to the involvement of multiple disciplinary models and coupling between the individual models. When the system inputs and outputs are varying over time and space, the reliability analysis is even more challenging. This paper proposes a surrogate model-based method for the reliability analysis of a multidisciplinary system with spatio-temporal output. The transient characteristics of the multidisciplinary system output under time-dependent variability are analyzed first. Based on the transient analysis, surrogate models are built for individual disciplinary analyses instead of a single surrogate model for the fully coupled analysis. To address the challenge introduced by the high-dimensionality of spatially varying inter-disciplinary coupling variables, a data compression method is first employed to convert the high-dimensional coupling variables into low-dimensional latent space. Kriging surrogate modeling is then used to build surrogates for the individual disciplinary models in the latent space. Based on the individual disciplinary surrogate models, reliability analysis of the coupled multidisciplinary system under time-dependent uncertainty is investigated. Further, epistemic uncertainty sources, such as data uncertainty and model uncertainty, lead to uncertainty in the reliability estimate. Therefore, an auxiliary variable approach is used to efficiently include the epistemic uncertainty sources within the reliability analysis. An aircraft panel subjected to hypersonic flow conditions is used to demonstrate the proposed method. The analysis involves four interacting disciplinary models, namely, aerodynamics, aerothermal analysis, heat transfer, and structural analysis. The results show that the proposed method is able to effectively perform reliability analysis of a multidisciplinary system with spatio-temporal output.     

A survey of hybrid optical data center network architectures

This paper presents a survey of data center network architectures that use both optical and packet switching components. Various proposed architectures and their corresponding network operation details are discussed. Electronic processing-based packet switch architectures and hybrid optical–electronic-based switch architectures are presented. These hybrid optical switch architectures use optical switching elements in addition to traditional electronic processing entities. The choice of components used for realizing functionality including the network interfaces, buffers, lookup elements and the switching fabrics have been analyzed. These component choices are summarized for different architectures. A qualitative comparison of the various architectures is also presented.     

Glucoamylase immobilized on montmorillonite: influence of nature of binding on surface properties of clay-support and activity of enzyme

Glucoamylase was immobilized on acid activated montmorillonite clay via two different procedures namely adsorption and covalent binding. The immobilized enzymes were characterized by XRD, NMR and N₂ adsorption measurements and the activity of immobilized glucoamylase for starch hydrolysis was determined in a batch reactor. XRD shows intercalation of enzyme into the clay matrix during both immobilization procedures. Intercalation occurs via the side chains of the amino acid residues, the entire polypeptide backbone being situated at the periphery of the clay matrix. ²⁷Al NMR studies revealed the different nature of interaction of enzyme with the support for both immobilization techniques. N₂ adsorption measurements indicated a sharp drop in surface area and pore volume for the covalently bound glucoamylase that suggested severe pore blockage. Activity studies were performed in a batch reactor. The adsorbed and covalently bound glucoamylase retained 49% and 66% activity of the free enzyme respectively. They showed enhanced pH and thermal stabilities. The immobilized enzymes also followed Michaelis–Menten kinetics. K _m was greater than the free enzyme that was attributed to an effect of immobilization. The immobilized preparations demonstrated increased reusability as well as storage stability.     

Modulation of renal injury in pcy mice by dietary fat containing n−3 fatty acids depends on the level and type of fat

Low-fat diets and diets containing n−3 fatty acids (FA) slow the progression of renal injury in the male Han:Sprague-Dawley (SPRD)-cy rat model of polycystic kidney disease. To determine whether these dietary fat effects are similar in females and in another model of renal cystic disease, in this study we used both male and female pcy mice to examine the effects of fat level and type on disease progression. Adult pcy mice were fed 4, 10, or 20 g soybean oil/100 g diet for 130 d in study 1. In study 2, weanling pcy mice were fed high or low levels of fat rich in 18∶2n−6 (corn oil, CO) 18∶3n−3 (flaxseed oil/CO 4∶1 g/g, FO), or 22∶6n−3 (algal oil/CO 4∶1 g/g, DO) for 8 wk. In adult pcy mice, low-compared with high-fat diets lowered kidney weights (2.4±0.2 vs. 3.1±0.2 g/100 g body weight, P=0.006) and serum urea nitrogen (SUN) (9.6±0.6 vs. 11.9±0.6 mmol/L, P=0.009), whereas in young pcy mice it reduced renal fibrosis volumes (0.44±0.04 vs. 0.62±0.04 mL/kg body weight, P<0.0001). FO feeding in young pcy mice mitigated the detrimental effects of high fat on fibrosis while not altering kidney size, function, and oxidative damage when compared with the CO-fed mice. In contrast, DO-compared with CO-fed mice had higher kidney weights (2.64±0.07 vs. 2.24±0.08 g/100 g body weight, P=0.005), SUN (9.4±0.57 vs. 7.0±0.62 nmol/L, P<0.0001), and cyst volumes (7.9±0.28 vs. 6.2±0.30 mL/kg body weight, P<0.0001) and similar levels of oxidative damage and fibrosis. The FA compositions of the diets were reflected in the kidneys: 18∶2n−6, 18∶3n−3, and 22∶6n−3 were the highest in the CO, FO, and DO diets, respectively. Dietary effects on kidney disease progression were similar in males and females. A low-fat diet slows progression of renal injury in male and female pcy mice, consistent with findings in the male Han:SPRD-cy rat. Dietary fat type also influenced renal injury, with flaxseed oil diets rich in 18∶3n−3 slowing early fibrosis progression compared with diets rich in 18∶2n−6 or in 22∶6n−3.     

Polar and nonpolar lipids and their fatty acid composition of a fewFusarium species

A few species ofFusarium have been evaluated for their potential to produce lipids. The isolates under investigation exhibited wide variation with respect to the mycelial weight, total lipid content and percentage composition of polar and nonpolar lipids in which triglycerides were the major components (81–90%). Palmitic, stearic, oleic and linoleic acids were the major fatty acids in both the fractions. The polar lipids contained higher levels of linoleic acid, whereas nonpolar lipids contained oleic acid as the predominant acid. Nonpolar lipids were more saturated than polar lipids.     

OPTIMAL DISTRIBUTION OF MULTIFUNCTIONAL CATALYSTS IN A PACKED BED REACTOR

The problem of the optimal distribution of two multifunctional catalysts is analyzed. Two methods for obtaining optimal catalyst profiles, an analytic-numeric method and the method of steepest ascent, are compared. Though the analytic-numeric method yields a more accurate solution, the method of steepest ascent is usually easier to apply. Optimal catalyst loading profiles are determined for two cases of commercial interest: selective oxidation of butene and naphtha reforming with bimetallic catalysts- A sequential loading of the bismuth molybdate and the vanadium phosphate catalysis is recommended for low butene concentration levels, while at higher butene levels a mixed loading of the two catalysts may be desirable. For commonly encountered naphtha feedstocks a sequential loading of the Pt-Re and the Pt-Ir catalysts tends to be optimal. These compare well with experimental evidence in the literature.