Numerical and experimental analysis of cold forming of titanium alloy sheets

Due to an increasing demand for the titanium drawn-parts, mainly from the aerospace and car industries, the demand for expertise in sheet-titanium forming grows. Although titanium combine many valuable features like lightweight with high strength and excellent corrosion resistance, its application is still limited because titanium processing, especially cold forming of titanium sheets poses many problems. In the paper technological problems with forming of titanium sheets is discussed. A special attention is paid to flexible forming. The experimental and numerical simulation results of semi-flexible forming are presented. The numerical analyses are carried out with the ADINA System v. 8.6 basing on the Finite Element Method (FEM). A spherical drawn-part made of Ti6Al4V titanium sheet is analysed. The material data, which are necessary for the numerical calculations, such as tensile strength Rm, yield point Re, R-value and hardening coefficient n were determined experimentally. The numerical calculations show good convergence with the experiment

Tameness of holomorphic closure dimension in a semialgebraic set

Given a semianalytic set S in a complex space and a point p in S, there is a unique smallest complex-analytic germ at p which contains the germ of S, called the holomorphic closure of S at p. We show that if S is semialgebraic then its holomorphic closure is a Nash germ, for every p, and S admits a semialgebraic filtration by the holomorphic closure dimension. As a consequence, every semialgebraic subset of a complex vector space admits a semialgebraic stratification into CR manifolds satisfying a strong version of the condition of the frontier.Comment: Published versio

Parton Branching in Color Mutation Model

The soft production problem in hadronic collisions as described in the eikonal color mutation branching model is improved in the way that the initial parton distribution is treated. Furry branching of the partons is considered as a means of describing the nonperturbative process of parton reproduction in soft interaction. The values of all the moments, and $C_q$, for q=2,...,5, as well as their energy dependences can be correctly determined by the use of only two parameters.Comment: 8 pages (LaTeX) + 2 figures (ps files), submitted to Phys. Rev.

Items on a Perceived Environment Tool are Grouped Differently in Low and High Income African American Women

Purpose: Prevalence of physical inactivity is greater in African American (AA) women than any other population sub group. The neighborhood environment is an important influence on physical activity, and accurate measurement of neighborhood perceptions is needed to determine the influence of neighborhood environment on physical activity. The purpose of this study was to investigate the stability of constructs represented by items from the International Prevalence Study (IPS) environmental module among high and low income AA women. Method: African American women (N=387) completed the IPS environmental module questionnaire which measured perception of neighborhood environment. A principle component analysis with varimax rotation was conducted using fifteen of seventeen items from the survey. Factor analysis was conducted separately for high and low income participants. Results: Four factors with eigenvalues ≥ 1.0 were extracted from the 15 item questionnaire for both groups. These four factors accounted for 56.6% of total variance in the high income group, and 53.1% of total variance in the low income group. The four factors for the high income group were Aesthetic Qualities and Social Environment, Neighborhood Safety, Neighborhood Infrastructure, and Destinations and Street Connectivity. The four factors for the low income group were Aesthetic Qualities and Social Environment, Neighborhood Safety, Opportunities to be active and Street Connectivity, and Public Transportation. Conclusion: The factors extracted for high and low income AA women may have been different due to dissimilarities in neighborhood infrastructure, design and quality. Inconsistent grouping of items into factors from the same instrument used to measure perceptions of neighborhood environment underscores the importance of accounting for differences in how high and low income residents perceive their neighborhood when considering physical activity interventions and policies

Fast Food and Supermarket Availability, Neighborhood Income and Health Outcomes in Public Housing Residents.

Purpose: The availability of fast food restaurants (FFRs) and supermarkets varies by neighborhood income level and may influence health outcomes such as body mass index (BMI) and blood pressure (BP). The purpose of this study was to determine whether neighborhood income moderates the association between fast food restaurant or supermarket availability and health outcomes in public housing residents. Method: Number of FFRs and supermarkets on every street segment in neighborhoods surrounding public housing developments (N=12) in Houston, Texas were counted, then aggregated at the neighborhood level. Residents (N=213) completed measures of BMI (kg/m2) and resting BP. Median household income at the census block level for each housing development was obtained from the 2006-2010 American Community Survey. Linear regression models determined whether availability of fast food restaurants and supermarkets predicts BMI or BP after controlling for age and gender, and if neighborhood income moderated these associations. Results: Participants were middle aged (M=43.5±17.1 years) females (n=138) and males (n=75). BP did not differ by gender (M=121.5/74.0±17.5/12.8 mmHg), females were on average obese (MBMI=33.0±8.7kg/ m2) and males were overweight (MBMI=33.0±8.7kg/ m2). Neighborhood income ranged from $9,226 to$57,618. There were (M=.003±.03) FFRs per neighborhood and (M=.001±.008) supermarkets per neighborhood. Bivariate correlations found that neighborhood income was associated with fast food restaurant (r=.205, p.05). Income did not moderate these associations (p\u3e.05). Conclusions: BP changes with age, and BMI varies by gender. After controlling for these variables, fast food restaurant and supermarket availability did not predict BMI or BP in public housing residents, and neighborhood income did not affect the direction of these associations. Actual consumption of the foods sold at these places may have a more direct relationship with health outcomes. Limited variability in the number of FFRs and supermarkets in each neighborhood may have diminished our ability to detect an effect of these neighborhood factors on BMI and BP

Numerical analysis of forming sheet panels with stiffening ribs

The transport industry, especially aviation, pays special attention to vehicle weight because lower weight means lower fuel consumption and in turn lower environmental pollution. Not only light metals like aluminium and magnesium alloys or titanium and its alloys are of interest in the transport industry but also new production technologies are taken into consideration as factors decreasing structure weight. Sheet metal forming offers light and strong components, therefore monolithic e.g. casting components are often replaced by drawn parts made of sheet metals. Forming large panels of thin sheets, especially hard-to-deform sheets with a high susceptibility to spring back, is a huge challenge. Forming both aluminium and titanium alloy sheets as well as nickel based steel sheets, which are the main structural materials in aviation, is difficult. Titanium, particularly titanium alloys, in comparison to steel and aluminium has a much more beneficial specific strength (strength-to-weight ratio) therefore it is used where high mechanical strength and low weight of the construction are especially essential. However, there are many technological problems, such as: poor drawability, high spring back and low tribological properties that have to be overcome in cold sheet-titanium forming. In the paper, numerical analysis of forming a part of a large sheet panel will be presented. The numerical simulation will be performed using the PamStamp program specially dedicated to sheet-metal forming. The program is based on the finite element method (FEM). The stress and strain distributions in the analysed part will be presented. The effect of the blank-holder force and frictional coefficient on the forming process will be studied. The quality of the obtained drawn part will be assessed based on the correctness of its shape and dimensions with reference ones, as well as on the thinning of the drawn part material

Chromatin association of the SMC5/6 complex is dependent on binding of its NSE3 subunit to DNA

SMC5/6 is a highly conserved protein complex related to cohesin and condensin, which are the key components of higher-order chromatin structures. The SMC5/6 complex is essential for proliferation in yeast and is involved in replication fork stability and processing. However, the precise mechanism of action of SMC5/6 is not known. Here we present evidence that the NSE1/NSE3/NSE4 sub-complex of SMC5/6 binds to double-stranded DNA without any preference for DNA-replication/recombination intermediates. Mutations of key basic residues within the NSE1/NSE3/NSE4 DNA-binding surface reduce binding to DNA in vitro. Their introduction into the Schizosaccharomyces pombe genome results in cell death or hypersensitivity to DNA damaging agents. Chromatin immunoprecipitation analysis of the hypomorphic nse3 DNA-binding mutant shows a reduced association of fission yeast SMC5/6 with chromatin. Based on our results, we propose a model for loading of the SMC5/6 complex onto the chromatin