Characterizations of friction welding joint interface for AISI 316

Because of heat amount is different from peripheral to central of friction welding interface, which is leaded to vary the characterizations along that interface. Current study, respectively, focused on the effect of different friction pressure on micro-structural and mechanical properties of that friction welding joint interface. Presently, these friction pressures are 110, 130, 150 and 170 MPa while kept all other conditions constant. The effects of different friction pressure on welding interface characterization were investigated by EDX, SEM, tensile, compression, impact and hardness tests. The tensile tests carried out on the standardized test piece with diameter 6 mm and 8 mm, thus, compression tests were extracted from the positions of 0°, 45° 90° with test specimen of 4 mm diameter and 6.5 mm length at weld center. Whereas, the impact test pieces were picked up in two positions, the first one is symmetrical, which it obtained to the respect of the rotation axis and the interface, on the other hand, the second one is non-symmetrical with the axis of rotation and symmetrical to the interface, for making the notch head coincide with the center of the welded joint, The obtained results showed that with reducing of friction pressure will present lack of bonding increasing from peripheral toward the welding center, which will responsible on reducing of the mechanical properties such as tensile, compression and impact strength.     

Synthesis of Benzophenones and in vitro Evaluation of Their Anticancer Potential in Breast and Prostate Cancer Cells

Breast and prostate cancers are frequently treated with chemotherapy. Several novel chemicals are being reported for this purpose, particularly synthetic and natural benzophenones. This work reports the synthesis of substituted 2-hydroxybenzophenones through 1,4-conjugate addition/intramolecular cycloaddition/dehydration of nitromethane on key intermediate chromones. Structures were extensively studied by means of 2D NMR spectroscopy and single-crystal XRD. Their cytotoxicity was evaluated in vitro in two breast cancer cell lines (MDA-MB-231 and T47-D) and one prostate cancer cell line (PC3). The most potent compound exhibited good cytotoxic effects against the three cancer cell lines (IC₅₀ values ranging from 12.09 to 26.49 μm ) and induced cell-cycle retardation only on prostate cancer cells, which suggested that it might exert cell-type-specific effects.     

A 3D unsplit-advection volume tracking algorithm with planarity-preserving interface reconstruction

A new volume tracking method is introduced for tracking interfaces in three-dimensional (3D) geometries partitioned with orthogonal hexahedra. The method approximates interface geometries as piecewise planar, and advects volumes in a single unsplit step using fully multidimensional fluxes that have their definition based in backward-trajectory remapping. By using multidimensional unsplit advection, the expense of high-order interface reconstruction is incurred only once per timestep. Simple departures from strict backward-trajectory remapping remove any need for consideration of volume computations involving shapes consisting of non-planar ruled surfaces. Second-order accuracy of the method is demonstrated even for vigorous 3D deformations.     

Bacteroides fragilis enterotoxin cleaves the zonula adherens protein, E-cadherin

Strains of Bacteroides fragilis associated with diarrheal disease (enterotoxigenic B. fragilis) produce a 20-kDa zinc-dependent metalloprotease toxin (B. fragilis enterotoxin; BFT) that reversibly stimulates chloride secretion and alters tight junctional function in polarized intestinal epithelial cells. BFT alters cellular morphology and physiology most potently and rapidly when placed on the basolateral membrane of epithelial cells, suggesting that the cellular substrate for BFT may be present on this membrane. Herein, we demonstrate that BFT specifically cleaves within 1 min the extracellular domain of the zonula adherens protein, E-cadherin. Cleavage of E-cadherin by BFT is ATP-independent and essential to the morphologic and physiologic activity of BFT. However, the morphologic changes occurring in response to BFT are dependent on target-cell ATP. E-cadherin is shown here to be a cellular substrate for a bacterial toxin and represents the identification of a mechanism of action, cell-surface proteolytic activity, for a bacterial toxin.     

Carbon segregation and inclusions effects on surface fracture morphology of a 12% chromium stainless steel

Martensitic 12% chromium stainless steel is generally used for the manufacture of water vapour turbine blades. This material, under these environmental conditions, develops fatigue corrosion with failure as a result of the segregation of certain constituent elements such as phosphorus (P) and sulphur (S),^[1–3] or the presence of some types of inclusions.^[2–4] To be able to understand and explain these phenomena, in situ characterization of the fractured surfaces were performed for two types of samples: steel 1 as manufactured turbine material whose fracture mode is intergranular and steel 2 issued from last stage turbine blades after 100 000 h service at 40 °C whose fracture mode is transgranular. The techniques used for characterization were scanning electron microscopy (SEM) coupled with the x-ray analysis by energy dispersive spectroscopy (EDS), and auger electron spectroscopy (AES). The Auger results enabled the understanding of the brittle to ductile transition for the material by showing the simultaneous diffusion of carbon from grain boundaries (GB) to grains (G) and chromium from G to GB. Furthermore, the heavy segregation of phosphorus at the GBs could explain the intergranular crack rupture traces observed in steel 2. SEM observations coupled with EDS analysis showed the presence of different types of non-metallic inclusions such as silicon-based complex inclusions and manganese sulfides (MnS). The presence of silicon-based complex inclusions at GB could explain the intergranular fracture mode previously reported. The characterization of the fracture appearance suggests also that MnS inclusions can act as nucleation sites for secondary microcracks at the GB level that were observed after service.     

Buoyancy effects on gaseous slip flow in a vertical rectangular microchannel

Consideration is given to the buoyancy effects on the fully developed gaseous slip flow in a vertical rectangular microduct. Two different cases of the thermal boundary conditions are considered, namely uniform temperature at two facing duct walls with different temperatures and adiabatic other walls (case A) and uniform heat flux at two walls and uniform temperature at other walls (case B). The rarefaction effects are treated using the first-order slip boundary conditions. By means of finite Fourier transform method, analytical solutions are obtained for the velocity and temperature distributions as well as the Poiseuille number. Furthermore, the threshold value of the mixed convection parameter to start the flow reversal is evaluated. The results show that the Poiseuille number of case A is an increasing function of the mixed convection parameter and a decreasing function of the channel aspect ratio, whereas its functionality on the Knudsen number is not monotonic. For case B, the Poiseuille number is decreased by increasing each of the mixed convection parameter, the Knudsen number, and the channel aspect ratio.     

Gripper Design for Radio Base Station Autonomous Maintenance System

For an autonomous system to perform maintenance tasks in a networking device or a radio base station (RBS), it has to deal with a series of technological challenges ranging from identifying hardware-related problems to manipulating connectors. This paper describes the development of a robot maintenance system dedicated to detect and resolve faulty links caused by unplugged or poorly connected cables. Although the maintenance system relies on four subsystems, we significantly focus on our low-cost and efficient custom gripper solution developed to handle RJ45 Ethernet connectors. To examine our gripper, we conducted three experiments. First, a qualitative questionnaire was submitted to 30 users in the case of the teleoperated scenario of the gripper attached to a robotic arm. Similarly, we also tested the automatic operation mode. The results showed that our system is reliable and delivers a highly efficient maintenance tool in both teleoperated and autonomous operation modes. The practical experiment containing the removal or unplugging of connectors demonstrated our gripper’s ability to adequately handle these, whereas the feedback from the questionnaire pointed to a positive user experience. The automatic test assessed the gripper’s robustness against the continuous operation.

     

Structural hidden Markov models for biometrics: Fusion of face and fingerprint

The goal of this paper is threefold: (i) propose a novel face and fingerprint feature modeling using the structural hidden Markov models (SHMMs) paradigm, (ii) explore the use of some feature extraction techniques such as ridgelet transform, discrete wavelet transform with various classifiers for biometric identification, and (iii) determine the best method for classifier combination. The experimental results reported in both fingerprint and face recognition reveal that the SHMMs concept is promising since it has outperformed several state-of-the-arts classifiers when combined with the discrete wavelet transform. Besides, this study has shown that the ridgelet transform without principal components analysis (PCA) dimension reduction fits better with the support vector machines (SVMs) classifier than it does with the SHMMs in the fingerprint recognition task. Finally, these results also reveal a small improvement of the bimodal biometric system over unimodal systems; which suggest that a most effective fusion scheme is necessary.     

SPIDER: An availability-aware framework for the service function chain placement in distributed scenarios

The network function virtualization (NFV) paradigm replaces hardware-dependent network functions by virtual network functions (VNFs) that can be deployed in commodity hardware, including legacy servers. Consequently, the use of NFV is expected to reduce operating and capital expenses, as well as improve service deployment operation and management flexibility. For many use cases, the VNFs must be visited and invoked following a specific order of execution in order to compose a complete network service, named service function chain (SFC). Nonetheless, despite the benefits from NFV and SFC virtualization technologies, their introduction must not harm network performance and service availability. On the one hand, redundancy is seen by network service planners as a mechanism well established to combat availability issues. At same time, there is a goal to optimize resource utilization in order to reduce operational expenditure. In this article, we share our experience in the design use of a framework, named SPIDER, focused on SFC placement that considers the network infrastructure condition and the required SFC availability to define the placement strategy. The SPIDER monitors the status of infrastructure nodes and links and defines which servers the VNFs should be placed on and the number of redundant replicas needed. We present a proof-of-concept of SPIDER using Kubernetes to launch the VNFs as containers. We also use Kubernetes to forward the traffic between the VNFs, composing the service chain. We perform experiments to evaluate the runtime of SPIDER and the SFC delay under different network conditions.     

Bending-stretching analysis of thick functionally graded micro-plates using higher-order shear and normal deformable plate theory

In the present article, higher-order shear and normal deformable plate theory together with modified couple stress theory are developed to study the bending analysis of thick functionally graded rectangular micro-plates. One material length scale parameter is used for capturing the size effects. Utilizing the variational approach and also a principle of virtual displacement, a new form of equilibrium equations and the corresponding boundary conditions are derived. It is assumed that material properties vary through the thickness according to the power law function. Finally, an analytical solution for the bending problem of a simply supported FG rectangular micro-plate is presented.