The promotion of spatial skills is essential in chemistry education. However, the process of acquiring these skills can be monotonous if learning is limited to the memorization of Newman projections or 3D molecular kits. Existing approaches to learning using visualizing tools require physical models which limit learning activities to within the classroom. Augmented reality (AR) in chemistry education allows students to see actual compound representation in a 3D environment, inspect compounds from multiple viewpoints, and control compounds interaction in real-time in any location. This facilitates the understanding of the spatial relations between compounds. We developed a methodology to use and assess an AR program to teach chemistry to associate degree science students. Figures of small organic molecules together with customized AR cards were used to let students appreciate the complexity of a 3D compound structure by viewing and rotating the depicted compounds. The effectiveness of learning chemistry using AR technology was evaluated. Quantitative questionnaire feedback results from students showed that 87% found that using AR technology for chemistry subjects was an effective teaching method that enhanced their learning, and students were satisfied with the AR educational app and the AR materials used. In a pre- and post-test evaluation of a group activity, students learned better and remembered more information about functional groups and drawings of complicated compounds after using AR technology. On the basis of our results, we can conclude that using AR has a positive impact on enthusiasm and learning in higher education chemistry courses for subdegree students, and this technology should be broadly used as a digital tool to promote active learning during the COVID-19 pandemic.

In application-level high bandwidth multicast (HBM), physical links can be shared by multiple long-lived unicast flows. We identify several data transfer patterns which can cause suboptimal bandwidth usage of narrow links and which have not been clearly identified in previous solutions for application-level HBM.We propose a distributed solution to avoid these problematic patterns, with which end systems are coordinated and each is responsible to forward a bounded amount of data. Consequently, the outgoing traffic of each end system is balanced and limited. It avoids congestion due to merging unicast flows, which increases the utilization of the narrow links. Receivers that are close by topologically request their data in a disjoint and coordinated fashion, which leads to much reduced duplicated data at the narrow links. Simulation results show that our solution can achieve higher throughputs at the receivers, which is due to more efficient utilization of the narrow links' bandwidth, than meshbased or multiple-tree approaches.

No abstract

No abstract

Achieving IP handoff with a short latency and minimal packet loss is essential for mobile devices that roam across IP subnets. Many existing solutions require changes to be made to the network or transport layer, and they tend to suffer from long handoff latency in either soft or hard handoff scenario, or both; and some are difficult to deploy in practice. We propose a new protocol, called the adaptive multipath protocol, to achieve efficient IP handoff. Based on link-layer signal strength measurements, two different schemes are used to handle soft and hard handoff respectively. Seamless IP handoff is achieved by using multiple transport layer connections on top of persistent link-layer connectivity during soft handoff. To achieve low handoff latency during hard handoff, a set of distributed sessions repositories (SRs), which are independent of the end hosts, are employed. Simulation results clearly support our claims. In particular, the latency for hard handoff is found to be as low as 50% of that of Fast handoff.