Scenario based distributed manufacturing simulation using HLA technologies

Simulating complex and distributed manufacturing systems is not easy using traditional simulation techniques. Manufacturing environment contains several systems that must interoperate and exchange information. A general software architecture is necessary to make manufacturing systems interrelated. This paper presents an overview of distributed manufacturing simulation as well as of information representation in distributed manufacturing simulation using high level architecture (HLA) and its object model template (OMT). The concept is explained with a scenario which is provided to better address the object class structure, interaction class structure, attribute, parameter and data type tables.     

HFE gene mutation is a risk factor for tissue iron accumulation in hemodialysis patients

Introduction: HFE gene mutations are responsible from iron overload in general population. Studies in hemodialysis patients investigated the effect of presence of HFE gene mutations on serum ferritin and transferrin saturation (TSAT) with conflicting results. However effect of HFE mutations on iron overload in hemodialysis patients was not previously extensively studied. Methods: 36 hemodialysis patients (age 51.3 ± 15.6, (18/18) male/female) and 44 healthy control subjects included in this cross sectional study. Hemoglobin, ferritin, TSAT in the preceding 2 years were recorded. Iron and erythropoietin (EPO) administered during this period were calculated. Iron accumulation in heart and liver was detected by MRI. Relationship between HFE gene mutation, hemoglobin, iron parameters and EPO doses, and tissue iron accumulation were determined. Findings: Iron overload was detected in nine (25%) patients. Hemoglobin, iron parameters, weekly EPO doses, and monthly iron doses of patients with and without iron overload were similar. There was no difference between control group and hemodialysis patients with respect to the prevalence of HFE gene mutations. Iron overload was detected in five of eight patients who had HFE gene mutations, but iron overload was present in 4 of 28 patients who had no mutations (P = 0.01). Hemoglobin, iron parameters, erythropoietin, and iron doses were similar in patients with and without gene mutations. HFE gene mutations remained the main determinant of iron overload after multivariate logistic regression analysis (P = 0.02; OR, 11.6). Discussion: Serum iron parameters were not adequate to detect iron overload and HFE gene mutation was found to be an important risk factor for iron accumulation.     

Development and Cyclic Behavior of U-Shaped Steel Dampers with Perforated and Nonparallel Arm Configurations

Metallic dampers are sacrificial devices (fuses) that dissipate significant energy during earthquakes while protecting other parts of structures from possible damage. In addition to numerous implementation opportunities of other base isolation systems, U-shaped dampers (UD) are one of the widely investigated and used devices in practice especially in Japan. The present study focuses on enhancing seismic performance of these types of dampers by changing their geometric properties. UDs with perforated (i.e. with holes) and/or nonparallel arms are developed for this purpose. For a better comparison, the criterion of equal material volume (or mass) has been utilized. Three dimensional finite element models of the new type of UDs are formed and investigated numerically under selected displacement histories. Based on the obtained hysteretic curves; dissipated energy intensities, effective stiffness ratios, reaction forces, effective damping ratios are evaluated in this parametric study. It is found that both damper types have merits in use of seismic applications and that the selection of the damper configuration is dependent on the design specific issues.     

Naturally nonanemic dialysis patients: Who are they?

Introduction Not only anemia, but also erythropoiesis stimulating agent (ESA)s for treating anemia may adversely affect prognosis of chronic hemodialysis patients. Various features of naturally (with no ESA usage) nonanemic patients may be useful for defining several factors in the pathogenesis of anemia. Methods Data, retrieved from the European Clinical Database (EuCliD)‐Turkey on naturally nonanemic prevalent chronic hemodialysis patients (n: 201) were compared with their anemic (those who required ESA treatment) counterparts (n: 3948). Findings Mean hemoglobin values were 13.5 ± 0.8 and 11.5 ± 0.9 g/dL in nonanemic and anemic patients, respectively (P < 0.001). Nonanemia status was associated with younger age, male gender, longer dialysis vintage, nondiabetic status, more frequent hepatitis‐C virus seropositivity and more frequent arteriovenous fistula usage. Serum ferritin and CRP levels and urea reduction ratio were higher in ESA‐requiring patients. One (99%) and two (95.3%) years survival rates of the “naturally nonanemic” patients were superior as compared to anemics (91.0% and 82.6%, respectively), (P < 0.001). Discussion “Naturally nonanemic” status is associated with better survival in prevalent chronic hemodialysis patients; underlying mechanisms in this favorable outcome should be investigated by randomized controlled trials including large number of patients.     

Calculation of Cross-sections and Astrophysical S-Factors for <Superscript>62</Superscript>Ni(α,n) and <Superscript>62</Superscript>Ni(α,γ) Reactions of Structural Fusion Material Nickel

Nickel is an important element in fusion reactor technologies and astrophysical applications. Therefore, the knowledge of astrophysical S-factors and cross-sections on nickel isotopes is needed. In this work, the cross sections of the ⁶²Ni(α,n) and ⁶²Ni(α,γ) reactions have been calculated. The alpha capture cross sections was calculated up to 10 MeV. In these theoretical calculations, the TALYS 1.6 and NON-SMOKER codes were used. Also for the ⁶²Ni(α,n) and ⁶²Ni(α,γ) reactions, we calculated the astrophysical S-factors that determine the probability of reaction in low energies. Results of our calculations were checked to the experimental data obtained from EXFOR database.     

Adaptive texture and color segmentation for tracking moving objects

Color segmentation is a very popular technique for real-time object tracking. However, even with adaptive color segmentation schemes, under varying environmental conditions in video sequences, the tracking tends to be unreliable. To overcome this problem, many multiple cue fusion techniques have been suggested. One of the cues that complements color nicely is texture. However, texture segmentation has not been used for object tracking mainly because of the computational complexity of texture segmentation. This paper presents a formulation for fusing texture and color in a manner that makes the segmentation reliable while keeping the computational cost low, with the goal of real-time target tracking. An autobinomial Gibbs Markov random field is used for modeling the texture and a 2D Gaussian distribution is used for modeling the color. This allows a probabilistic fusion of the texture and color cues and for adapting both the texture and color over time for target tracking. Experiments with both static images and dynamic image sequences establish the feasibility of the proposed approach.     

Theoretical Investigation of a Time-Suboptimal Control Method for Rotational Motions of Industrial Manipulators End-Effectors

A time suboptimal control method is developed for rotational motions of industrial manipulators end-effectors. A set of nonlinear equations is obtained and linearized at each time step of the motion. A method which yields the time suboptimal joint angular velocities as functions of time is developed by considering constraints on joint velocities as well as joint and tool center point frame accelerations. The method is demonstrated on a six-degree-of-freedom elbow-type manipulator.     

Numerical solutions of 2-D steady incompressible flow over a backward-facing step, Part I: High Reynolds number solutions

Numerical solutions of 2-D laminar flow over a backward-facing step at high Reynolds numbers are presented. The governing 2-D steady incompressible Navier-Stokes equations are solved with a very efficient finite difference numerical method which proved to be highly stable even at very high Reynolds numbers. Present solutions of the laminar flow over a backward-facing step are compared with experimental and numerical results found in the literature.