Microstructure of the heat-affected zone in 17–4 PH stainless steel

The microstructure of the heat-affected zone (HAZ) in bead-on-plate welded 17–4 PH stainless steel was studied with special reference to the roles of prior heat treatment and heat input during welding. The HAZ in solution-annealed condition consists of three different microstructural zones containing: (i) retransformed martensite and reformed austenite; (ii) overaged martensite; and (iii) under-aged martensite. In aged condition the HAZ consists of zones (i) and (ii), while in overaged condition it consists almost entirely of zone (ii). The HAZ in solution-annealed and aged conditions is characterised by steep gradients in hardness, while in overaged condition it has uniform hardness throughout. A good correlation was obtained between the calculated temperature distribution in the HAZ and the observed microstructural features.     

Electrochemical Techniques for Corrosion Rate Determination in Ceramics

Standard electrochemical test procedures have been successfully applied to determine the corrosion rates of SiC-based ceramics in aqueous reagents. Direct-current polarization measurements in HCI solutions indicate that the corrosion rate of α-SiC is 0.0050 ± 0.0002 mil/yr and is fairly independent of HCI concentration. The corrosion rates of α-SiC are significantly lower than those for reaction-sintered SiC in all of the electrolytes used including HCI, HNO₃, H₃, H₃PO₄, and aqua regia. It is believed that the free Si contained in the reaction-sintered SiC is responsible for the higher corrosion rates. It has been shown that electrochemical techniques are reproducible and eminently suitable for determining very low corrosion rates encountered in ceramics.     

Serum high density lipoprotein and its relationship to cardiovascular disease risk factor variables in children—The bogalusa heart study

Serum high density lipoprotein is increasingly recognized as a negative risk for cardiovascular disease. The distribution and interrelationship of serum lipids, lipoproteins, anthropometric measurements and blood pressures were determined in some 5,000 children. Children had mean±S.D. α-lipoprotein cholesterol levels (mg/100 ml) of 36±15 at birth, 51±22 at 6 mo, 53±18 at 1 yr, 60±19 at preschool age (21/2−51/2 yr) and 68±22 at school age (5–14 yr), reflecting a sharp increase in α-lipoprotein between birth and school-age years, when these levels remained relatively stable through age 14. Although white children tended to have higher levels of total cholesterol and α-lipoprotein at birth than black children, during childhood this trend was reversed and the differences were pronounced in school-age children (p<0.0001). Unlike in adulthood, boys had slightly higher levels of α-lipoprotein than girls. The α-lipoprotein was negatively correlated with pre-β-lipoprotein and to a lesser extent with β-lipoprotein classes. There was an inverse relationship between α-lipoprotein and obesity with a consistently significant relationship (p<0.01) in older children (10–14 yr). Children with higher levels of α-lipoprotein have lower levels of blood pressure, β-lipoprotein and a lower obesity index.     

Robust numerical scheme for singularly perturbed convection–diffusion parabolic initial–boundary-value problems on equidistributed grids

In this article, we study the numerical solution of singularly perturbed parabolic convection–diffusion problems exhibiting regular boundary layers. To solve these problems, we use the classical upwind finite difference scheme on layer-adapted nonuniform meshes. The nonuniform meshes are obtained by equidistributing a positive monitor function, which depends on the second-order spatial derivative of the singular component of the solution. The truncation error and the stability analysis are obtained. Parameter-uniform error estimates are derived for the numerical solution. Semilinear IBVPs are also solved. Numerical experiments are carried out to support the theoretical results.     

A new continuous-time formulation for scheduling crude oil operations

In today's competitive business climate characterized by uncertain oil markets, responding effectively and speedily to market forces, while maintaining reliable operations, is crucial to a refinery's bottom line. Optimal crude oil scheduling enables cost reduction by using cheaper crudes intelligently, minimizing crude changeovers, and avoiding ship demurrage. So far, only discrete-time formulations have stood up to the challenge of this important, nonlinear problem. A continuous-time formulation would portend numerous advantages, however, existing work in this area has just begun to scratch the surface. In this paper, we present the first complete continuous-time mixed integer linear programming (MILP) formulation for the short-term scheduling of operations in a refinery that receives crude from very large crude carriers via a high-volume single buoy mooring pipeline. This novel formulation accounts for real-world operational practices. We use an iterative algorithm to eliminate the crude composition discrepancy that has proven to be the Achilles heel for existing formulations. While it does not guarantee global optimality, the algorithm needs only MILP solutions and obtains excellent maximum-profit schedules for industrial problems with up to 7 days of scheduling horizon. We also report the first comparison of discrete- vs. continuous-time formulations for this complex problem.     

Pricing and capacity planning for product-line expansion and reduction

We investigate optimal pricing and capacity planning decisions for product-line settings such as introducing a new product or dropping an existing one. We consider a two-product, two-period model with stochastic demands, where price and capacity decisions are made at the outset. Investment in capacity must be traded-off against the possibility of buying at higher spot market prices due to shortage in capacity or charging a higher price to manage the demand. Prior studies argue that introducing an additional product to the product-line strains capacity, resulting in an increase in the price of an existing product. In contrast, we find that introducing a new product can also result in a drop in price of an existing product, enabling strategic pricing by firms. The necessary condition for this to occur is that the demand uncertainties for the products are of similar magnitude and negatively correlated. Similar insights are obtained for the setting where an existing product is dropped from the product-line. Hence, product-market decisions and contextual factors play a role in capacity planning, capacity cost allocation and pricing.     

Correlation-based interferometric method of evaluating the beat length

A new, to our knowledge, interferometric method of measuring beatlengths in polarization-maintaining fibers that is based on correlationmeasurements is presented.     

Integrating Visual Analytics Support for Grounded Theory Practice in Qualitative Text Analysis

We present an argument for using visual analytics to aid Grounded Theory methodologies in qualitative data analysis. Grounded theory methods involve the inductive analysis of data to generate novel insights and theoretical constructs. Making sense of unstructured text data is uniquely suited for visual analytics. Using natural language processing techniques such as parts‐of‐speech tagging, retrieving information content, and topic modeling, different parts of the data can be structured and semantically associated, and interactively explored, thereby providing conceptual depth to the guided discovery process. We review grounded theory methods and identify processes that can be enhanced through visual analytic techniques. Next, we develop an interface for qualitative text analysis, and evaluate our design with qualitative research practitioners who analyze texts with and without visual analytics support. The results of our study suggest how visual analytics can be incorporated into qualitative data analysis tools, and the analytic and interpretive benefits that can result.     

Animation Setup Transfer for 3D Characters

We present a general method for transferring skeletons and skinning weights between characters with distinct mesh topologies. Our pipeline takes as inputs a source character rig (consisting of a mesh, a transformation hierarchy of joints, and skinning weights) and a target character mesh. From these inputs, we compute joint locations and orientations that embed the source skeleton in the target mesh, as well as skinning weights to bind the target geometry to the new skeleton. Our method consists of two key steps. We first compute the geometric correspondence between source and target meshes using a semi‐automatic method relying on a set of markers. The resulting geometric correspondence is then used to formulate attribute transfer as an energy minimization and filtering problem. We demonstrate our approach on a variety of source and target bipedal characters, varying in mesh topology and morphology. Several examples demonstrate that the target characters behave well when animated with either forward or inverse kinematics. Via these examples, we show that our method preserves subtle artistic variations; spatial relationships between geometry and joints, as well as skinning weight details, are accurately maintained. Our proposed pipeline opens up many exciting possibilities to quickly animate novel characters by reusing existing production assets.