No abstract

Real world MANET routing protocol implementations generally use layer three mechanisms for carrying out connectivity maintenance tasks. In many cases, such mechanisms are based on periodical transmission of Hello messages. When topology changes occur frequently, usage of higher Hello rates than default may lead to higher end-to-end connectivity and available bandwidth. However, in rather static conditions, low Hello rates are adequate to avoid unnecessary bandwidth and power consumption waste. In this paper we present Adaptive Hello Rate (AHR), a two-state adaptive mechanism for adjusting HELLO_INTERVAL parameter in AODV. We evaluate AHR by conducting a set of experiments in real ad-hoc testbeds. Results quantify the potential benefits and tradeoffs of the proposed solution.

Cr-Mo steel reactors being purchased for the oil refineries, gasification, and other industries have excellent standards for achieving fit for service designs, material specifications, and fabrication requirements. These standards include the ASME Pressure Vessel Code and API Recommended Practice (RP) 934-A for the 2¼Cr-1Mo alloy family and RP 934-C for 1¼Cr-½Mo. The RPs’ scopes indicate that they were developed for the most severe, high pressure refinery services, which typically require thick wall reactors. However, these standards are also widely used by industry as guidance for thinner Cr-Mo equipment. This paper aims to identify and present the appropriate requirements derived from the RPs that can be justified for less severe services and/or thin wall equipment falling outside the intended scope of API RP 934-A and 934-C.

Background: Laparoendoscopic single site surgery (LESS) is feasible for more complex procedure types, but the technical challenges and learning curve posed by LESS makes traditional multi-incision laparoscopy still the preferred technique. The aims of this study were to understand the restricted mobility and positional requirements of these more complex procedures and to generate innovative instrument designs to overcome these restrictions. Methods: A two-phase study was conducted where three lightly-embalmed (fresh tissue) cadavers were utilized to estimate in vivo mobility restriction and positional requirements. These data were combined to quantifying instrument force and positional requirements to develop a novel design for a LESS-specific grasper. Results: The LESS-specific has an ergonomic curved axial handle and locking mechanism that enables surgeons to relax their grip without the grasper releasing. Conclusion: Further design adaptations are needed to optimize the size, angles, and curvature of the tool, as well as to add two points of articulation for rapid intracorporeal adjustment.