An improved analytical model of the separation region on boattail nozzles at subsonic speeds

A practical engineering calculation was developed to model the viscous effects of a separated, reverse flow region on afterbody pressures and drag. This viscous calculation was iteratively coupled with an inviscid flow calculation by means of an aerodynamic interface. A standard boundary layer displacement thickness was used to modify the afterbody shape where the flow was attached. A discriminating streamline calculation was developed to account for displacement effects of the reverse flow in separated regions with and without a flowing jet. The viscous flow calculation was coupled with a potential flow calculation. The analysis accurately predicted afterbody pressures and drag with variations in Reynolds number, Mach number, and afterbody shape

Investigation of functions characterizing the flow curves of cast magnesium alloy MgAl9Zn1

The article presents the results of testing the flow curves of cast magnesium alloy MgAl9Zn1. Experimental tests were carried out on a deformation dilatometer in a compression test of cylindrical specimens heated to 380 °C, 400 oC, 420 °C at strain rates of 0,1 s-1, 1 s-1, 10 s-1. The experimental curves were described by functions used in programs for simulating metal forming processes based on the finite element method. The Generalized Reduced Gradient optimization method (GRDM) implemented in Microsoft Excel was used to determine the function coefficients. Based on the results obtained, the best functions characterizing the flow curves were selected for use in describing the material models used in numerical simulations of cast magnesium alloy MgAl9Zn1

Investigation of functions characterizing the flow curves of cast magnesium alloy MgAl9Zn1

The article presents the results of testing the flow curves of cast magnesium alloy MgAl9Zn1. Experimental tests were carried out on a deformation dilatometer in a compression test of cylindrical specimens heated to 380 °C, 400 oC, 420 °C at strain rates of 0,1 s-1, 1 s-1, 10 s-1. The experimental curves were described by functions used in programs for simulating metal forming processes based on the finite element method. The Generalized Reduced Gradient optimization method (GRDM) implemented in Microsoft Excel was used to determine the function coefficients. Based on the results obtained, the best functions characterizing the flow curves were selected for use in describing the material models used in numerical simulations of cast magnesium alloy MgAl9Zn1

Loss of expression of ATM is associated with worse prognosis in colorectal cancer and loss of Ku70 expression is associated with CIN

Repair of double strand DNA breaks (DSBs) is pivotal in maintaining normal cell division and disruption of this system has been shown to be a key factor in carcinogenesis. Loss of expression of the DSB repair proteins have previously been shown to be associated with poorer survival in colorectal cancer. We wished to ascertain the relationship of altered expression of the DSB repair proteins γ-H2AX (gamma-H2AX), ATM and Ku70 with biological and clinico-pathological features of colorectal cancer. 908 tumours from the VICTOR clinical trial of stage II/III colorectal cancer were analysed for expression of γ-H2AX, ATM and Ku70 using immunohistochemistry. Expression levels were correlated with CIN and with diseasefree survival, correcting for microsatellite instability, BRAF/KRAS mutation status, Dukes stage, chemo/radiotherapy, age, gender and tumour location. Down-regulated Ku70 expression was associated with chromosomal instability (p=0.029) in colorectal cancer. Reduced ATM expression was an independent marker of poor disease-free survival (HR=1.67, 95% CI 1.11-2.50, p=0.015). For Ku70, further studies are required to investigate the potential relationship of non-homologous end joining with chromosomal instability. Loss of ATM expression might serve as a biomarker of poor prognosis in colorectal cancer

Self-piercing riveting-a review

© The Author(s) 2017. This article is published with open access at Springerlink.com.Self-piercing riveting (SPR) is a cold mechanical joining process used to join two or more sheets of materials by driving a rivet piercing through the top sheet or the top and middle sheets and subsequently lock into the bottom sheet under the guidance of a suitable die. SPR is currently the main joining method for aluminium and mixed-material lightweight automotive structures. SPR was originated half century ago, but it only had significant progress in the last 25 years due to the requirement of joining lightweight materials, such as aluminium alloy structures, aluminium-steel structures and other mixed-material structures, from the automotive industry. Compared with other conventional joining methods, SPR has many advantages including no pre-drilled holes required, no fume, no spark and low noise, no surface treatment required, ability to join multi-layer materials and mixed materials and ability to produce joints with high static and fatigue strengths. In this paper, research investigations that have been conducted on self-piercing riveting will be extensively reviewed. The current state and development of SPR process is reviewed and the influence of the key process parameters on joint quality is discussed. The mechanical properties of SPR joints, the corrosion behaviour of SPR joints, the distortion of SPR joints and the simulation of SPR process and joint performance are reviewed. Developing reliable simulation methods for SPR process and joint performance to reduce the need of physical testing has been identified as one of the main challenges.Peer reviewe

Influence of Experimental Setup Parameters on Ultrasonic Assisted Micro-Upsetting

The progressive development of miniature systems increases the demand for miniature parts. Reducing the size of manufactured components on one hand is a serious challenge for traditional technologies, but on the other hand, mainly by removing the energy barrier opens the possibility of using other unconventional techniques. A good example is the ultrasonic excitation of the punch during the micro-upsetting process. The anti-barreling phenomenon and dependent on the amplitude of vibrations, intensive deformation of the surface layers in contact with the tools at both ends of the sample was noted. Based on the measured strains and stresses, an increase in temperature in the extreme layers to approx. 200°C was suggested. By adopting a simplified dynamic model of the test stand, the possibility of detaching the surface of the punch from the surface of the sample was demonstrated