Stress transmission through three-dimensional granular crystals with stacking faults

We explore the effect of stacking fault defects on the transmission of forces in three-dimensional face-centered-cubic granular crystals. An external force is applied to a small area at the top surface of a crystalline packing of granular beads containing one or two stacking faults at various depths. The response forces at the bottom surface are measured and found to correspond to predictions based on vector force balance within the geometry of the defects. We identify the elementary stacking fault as a boundary between two pure face-centered-cubic crystals with different stacking orders. Other stacking faults produce response force patterns that can be viewed as resulting from repetitions of this basic defect. As the number of stacking faults increases, the intensity pattern evolves toward that of an hexagonal-close-packed crystal. This leads to the conclusion that the force pattern of that crystal structure can be viewed as the extreme limit of a face-centered-cubic crystal with a stacking fault at every layer.This work was supported by NSF-CTS 0090490 and by the NSF MRSEC Program under DMR-0213745. MJS acknowledges support by the University of Chicago MRSEC Summer 2002 REU program.     

In-Situ Analyzing the Influence of Thermoelectromagnetic Convection on the Nucleation Ahead of the Advancing Interface During Directional Solidification

Sn-3wt%Pb alloy was directionally solidified without and with a 0.08T transverse magnetic field(TMF),and real-time recorded by in-situ synchrotron X-ray imaging.Results indicate that TMF shortened the distance from the location of nucleation to the advancing interface,and accelerated the growth rate of the equiaxed crystal,which caused the columnar-to-equiaxed transition(CET)finally.The thermoelectromagnetic convection(TEMC)in front of the interface and around the crystal’s dendritic branch should respond to changes of the distance and the growth rate.     

A case study on the object-oriented framework for modeling product families with the dominant variation of the topology in the one-of-a-kind production

Traditional configuration-based product family modeling techniques do not yield favorable solutions for modeling the product families with the dominant product topology variations. This paper presents the case study for the modeling of variations of the product configuration, parameters, and topologies in mass production of custom windows and doors in a one-of-a-kind production (OKP) company. The case study is based on the object-oriented product family modeling framework we developed for OKP which is characterized by the dominant product variation by topology. The problem of variation in topology in our framework is solved by the manual model transformation in the computer-aided design module which creates a new metamodel of products with the desired topology and which is the basis for a further, automatic model transformation. Usage of our framework has a positive effect on the level of the product customizations and shortening of the leading time which helps OKP companies in obtaining a better position at the market. Our software solution for the designing and manufacturing of custom windows and doors based on our framework is implemented in more than 300 mostly small- and medium-sized enterprises. It proves our concept which can be used for the realization of the information systems for computer-aided one-of-a-kind production in the companies with a different production plan.     

A Genomics-Based Model for Prediction of Severe Bioprosthetic Mitral Valve Calcification

Severe bioprosthetic mitral valve calcification is a significant problem in cardiovascular surgery. Unfortunately, clinical markers did not demonstrate efficacy in prediction of severe bioprosthetic mitral valve calcification. Here, we examined whether a genomics-based approach is efficient in predicting the risk of severe bioprosthetic mitral valve calcification. A total of 124 consecutive Russian patients who underwent mitral valve replacement surgery were recruited. We investigated the associations of the inherited variation in innate immunity, lipid metabolism and calcium metabolism genes with severe bioprosthetic mitral valve calcification. Genotyping was conducted utilizing the TaqMan assay. Eight gene polymorphisms were significantly associated with severe bioprosthetic mitral valve calcification and were therefore included into stepwise logistic regression which identified male gender, the T/T genotype of the rs3775073 polymorphism within the TLR6 gene, the C/T genotype of the rs2229238 polymorphism within the IL6R gene, and the A/A genotype of the rs10455872 polymorphism within the LPA gene as independent predictors of severe bioprosthetic mitral valve calcification. The developed genomics-based model had fair predictive value with area under the receiver operating characteristic (ROC) curve of 0.73. In conclusion, our genomics-based approach is efficient for the prediction of severe bioprosthetic mitral valve calcification.     

Increasing the Level of Automation in the Forestry Logging Process with Crane Trajectory Planning and Control

Working with forestry machines requires a great deal of training to be sufficiently skilled to operate forestry cranes. In view of this, it would be desirable within the forestry industry to introduce automated motions, such as those seen in robotic arms, to shorten the training time and make the work of the operator easier. Motivated by this fact, we have developed two experimental platforms for testing control systems and motion‐planning algorithms in real time. They correspond to a laboratory setup and a commercial version of a hydraulic manipulator used in forwarder machines. The aim of this article is to present the results of this development by providing an overview of our trajectory‐planning algorithm and motion‐control method, with a subsequent view of the experimental results. For motion control, we design feedback controllers that are able to track reference trajectories based on sensor measurements. Likewise, we provide arguments to design controllers in an open‐loop for machines that lack sensing devices. Relying on the tracking efficiency of these controllers, we design time‐efficient reference trajectories of motions that correspond to logging tasks. To demonstrate performance, we provide an overview of extensive testing done on these machines.