Worcester Polytechnic Institute

About: Worcester Polytechnic Institute is a education organization based out in Worcester, Massachusetts, United States. It is known for research contribution in the topics: Population & Data envelopment analysis. The organization has 6270 authors who have published 12704 publications receiving 332081 citations. The organization is also known as: WPI.

Average age of information for status update systems with an energy harvesting server

Abstract: This paper investigates the age of information in a single-source status update system with energy constraints. Specifically, a source provides status updates to a destination through a server assumed to have a battery with finite capacity that is replenished by harvesting energy. Arrival times of the status updates at the source and energy units at the server are assumed to be random according to independent Poisson processes. Service times are also assumed to be exponentially distributed and independent of the status and energy arrivals. The server is assumed to always be able to harvest energy when no information packet from the source is in service and the battery is not full. With regards to harvesting energy while packets are in service, this paper analyzes the average age of information both for servers that are able or unable to perform simultaneous service and energy harvesting. Closed-form expressions for the average age in terms of the system parameters are derived. Simulation results confirm the analysis and numerically demonstrate the performance advantage of servers with simultaneous service and energy harvesting.

Effects of Warm-Mix Asphalt Additives on Workability and Mechanical Properties of Reclaimed Asphalt Pavement Material

Abstract: The soaring cost of liquid asphalt binder and anticipated stricter environmental regulations have driven highway agencies to maximize the amount of reclaimed asphalt pavement (RAP) used for pavement construction. However, because of already aged and stiffened asphalt binder in RAP, the use of high percentages of RAP in hot-mix asphalt (HMA) presents many challenges. Problems with workability and compactability during construction need to be resolved first. This study investigated the feasibility of using 100% RAP HMA as a base course with warm-mix asphalt (WMA) additives (Sasobit H8 or Advera zeolite) at a lower temperature (125°C). Mix samples (control set with 100% RAP; a set with 100% RAP plus Sasobit H8 at 1.5%, 2.0%, and 5.0%; and a set with 100% RAP plus Advera zeolite at 0.3%, 0.5%, and 0.7%) were compacted with 50 gyrations. Their workability, bulk specific gravity, indirect tensile strength at 0°C, and moduli at 0°C, 26.7°C, and 50°C were determined. The effects of different amounts of WMA additi...