TCP HACK: TCP Header Checksum Option to Improve Performance Over Lossy Links

In recent years, wireless networks have become increasingly common and an increasing number of devices are communicating with each other over lossy links. Unfortunately, TCP performs poorly over lossy links as it is unable to differentiate the loss due to packet corruption from that due to congestion. In this paper, we present an extension to TCP which enables TCP to distinguish packet corruption from congestion in lossy environments resulting in improved performance. We refer to this extension as the HeAder ChecKsum option (HACK). We implemented our algorithm in the Linux kernel and performed various tests to determine its effectiveness. Our results have shown that HACK performs substantially better than both SACK and NewReno in cases where burst corruptions are frequent. We also found that HACK can co-exist very nicely with SACK and performs even better with SACK enabled

TCP-friendly traffic conditioning in DiffServ networks: A memory-based approach

10.1016/S1389-1286(01)00281-XComputer Networks386731-743CNET

Evaluation of tribological property and coating reliability of alumina and aluminum silicate-coated A356 aluminum alloy

Material loss due to relative motion between the contact surfaces causes surface degradation leading to premature failure of engineering systems. Of the several techniques to improve the wear resistance of rubbing components, the process of providing a hard protective surface coating has gained tremendous significance. Aluminum alloys used in engineering applications are exposed to rubbing, resulting in progressive wear. Sol-gel coating is a widely accepted surface coating technique for aluminum alloys, and this paper focuses on alumina and aluminum silicate coating applied to aluminum alloys. The tribological characteristics such as coefficient of friction (COF) and volumetric wear losses (VWL) are evaluated using a pin on disc (POD) tribometer. Finite-element analysis (FEA) plays a vital role in bringing an approximate solution to various engineering and non-engineering problems. The POD tribometer is modelled in the design modeller of the Ansys workbench based on the Archard wear model. The coating reliability is experimentally estimated based on its tribological properties. Surface hardness is measured by microhardness indentation test, and materials characterization is done using atomic force microscopy (AFM) and Fourier transform infrared radiation (FTIR) spectroscopy. It is observed that alumina coating exhibits better tribological properties than aluminum silicate-coated A356 aluminum alloy. </jats:p

Estimation of thermal stress at the interface of sliding in a pin on disc tribometer using finite element approach

Abstract Finite Element Method (FEM), introduced at the end of sixties, is used for solving engineering problems by mathematical formulations. The present study estimates the thermal stresses and temperature distribution induced at the contact surface during frictional sliding. The pin on disc tribometer is modelled as per ASTM G99 in ANSYS Workbench simulation software with the help of User Defined Function (UDF). Aluminium alloy 6061 coated with Yttrium stabilized zirconia is used for the analysis where the alloy is subjected to continuous sliding motion against aluminium oxide disc material. User Defined Results are employed in this analysis for the determination of thermal stress generated at the contact surface during frictional sliding. Temperature distribution is determined and is represented in contours.</jats:p

Numerical Analysis of Wear Characteristics of Zirconia Coated Aluminum 6061 Alloy

Abstract Any mechanical systems with moving parts encounter the problem of wear and industriesacross the world are trying to reduce its detrimental effects. In this paper, Finite Element Method (FEM) is used for analysis of wear characteristics of Yttrium stabilized Zirconia coating on Al6061 Aluminum alloy. Aluminum alloy 6061, having high strength to weight ratio, is used as the substrate material upon which Thermal Barrier Coating (TBC) is applied. Friction and wear coefficient obtained from Continuous Sliding Motion (CSM) of Yttrium stabilized Zirconia coating over Aluminum oxide disc material is used for the numerical analysis inputs. Tribological characteristics such as contact pressure, frictional stress and wear thickness are evaluated numerically using ANSYS Mechanical based on Archard wear model.</jats:p

Microstructure and mechanical properties of AlNbTaZr-Al2O3 refractory high entropy alloy reinforced Al6061 metal matrix composite

Traditional ceramic-reinforced Metal Matrix Composites (MMCs) often exhibit challenges such as weak interfacial bonding, ceramic particle fragmentation, and thermal expansion mismatch, which collectively compromise their plasticity and toughness. To overcome these limitations, the present study investigates a novel composite system by reinforcing Al6061 matrix with AlNbTaZr-Al2O3 Refractory High Entropy Alloy (RHEA) powders which were fabricated through mechanical alloying for 30 h. The research focuses on analyzing the structural evolution, mechanical properties, and wear behavior of the resulting Al6061–AlNbTaZr–Al2O3 composite. X-ray diffraction (XRD) confirms progressive nano structuring of RHEA powders with increased milling duration. Transmission Electron Microscopy (TEM) reveals an average grain size of 246.7 nm, with a maximum of 385.1 nm. Optical microscopy shows pronounced grain refinement in the composite, attributed to Dynamic Recrystallization (DRX) induced by RHEA particles. Mechanical testing demonstrates a 69.4 % increase in tensile strength for the composite (164.2 MPa) compared to pure Al6061 (96.9 MPa), and a substantial enhancement in ultimate compressive strength (326.6–335.3 MPa vs. 236.1 MPa). Tribological analysis reveals a lower and more stable coefficient of friction (0.45–0.55) than Al6061 (0.57 at 20 kN), reflecting improved wear resistance due to reduced material removal and the reinforcement effect of the RHEA phase. Based on the results, the Al6061–AlNbTaZr–Al2O3 composite exhibits significantly enhanced mechanical strength, refined microstructure, and superior wear resistance, making it a promising candidate for structural and tribological applications in aerospace, automotive, and defense industries where lightweight, high-strength, and wear-resistant materials are essential