Methane conversion to ethane in the presence of iron‐ and manganese‐promoted sulfated zirconia

Sulfated zirconia promoted with 1.0 wt% Fe and 0.5 wt% Mn converts methane into ethane with traces of ethylene and acetylene. The initial reaction rate at 723 K and a methane partial pressure of 20 kPa was found to be about 10^-9 mol(CH ₄) (g s)^-1, and deactivation was rapid, with the reaction rate declining to half the maximum rate within an hour. This revised version was published online in July 2006 with corrections to the Cover Date.     

About Deterministic and non‐Deterministic Vehicular Communications over DSRC/802.11p

In this work, we introduce a priority‐aware deterministic access protocol called Vehicular Deterministic Access (VDA). VDA is based on 802.11p/DSRC and allows vehicles to access the shared medium in collision‐free periods. Particularly, VDA supports two types of safety services (emergency and routine safety messages) with different priorities and strict requirements on delay. To avoid long delays and high packet collisions, VDA allows vehicles to access the wireless medium at selected times with a lower contention than would otherwise be possible within a two‐hop neighborhood by the classical 802.11p Enhanced Distributed Channel Access or Distributed Coordination Function schemes. A non‐VDA‐enabled vehicle, that is, a vehicle not configured with the optional VDA capability over 802.11p, may start transmitting on the shared channel just before or during the VDA opportunities reserved for vehicles with VDA capabilities. To avoid the aforementioned issues and prevent interfering transmissions from VDA‐enabled vehicles and non‐VDA‐enabled vehicles, we also proposed a novel scheme called extended VDA. We analyzed the impact of several design tradeoffs between the contention free period/contention period dwell time ratios on the performance of safety applications with different priorities for VDA and extended VDA. Simulations show that the proposed schemes clearly outperform the backoff‐based schemes currently used by 802.11p in high communication density conditions while bounding the transmission delay of safety messages and increasing the packet reception rate. Copyright © 2012 John Wiley & Sons, Ltd.     

Service-Oriented Sensor-Actuator Networks [Ad Hoc and Sensor Networks]

Most approaches developed to query sensor-actuator networks (SANETs) are either application-specific or generic. Application-specific SANETs provide limited reusability, are not cost effective, and may require extensive reprogramming efforts to make the network able to serve new applications. Generic SANETs usually require that a sizeable code be deployed on the nodes regardless of the specific requirements of the application at hand. More important, they may not be optimized to fully exploit the specific characteristics and query patterns of a given application. In this article we introduce service-oriented SANETs (SOSANETs) as a novel approach to building customizable SANETs. SOSANETs provide the benefits of both application-specific SANETs (e.g., energy efficiency, scalability) and generic SANETs (e.g., reusability) and avoid most of their limitations. We implemented our approach in TinySOA, a SOSANET developed on top of TinyOS. We conducted an evaluation of TinySOA that included a comparison with TinyDB, an established query processing system for sensor networks. The obtained empirical results show that TinySOA outperforms TinyDB in many aspects including energy consumption, scalability, and response time.     

A semantic service-oriented platform for energy efficient buildings

The construction industry is under pressure to increase the sustainability of its practices to meet UK commitments for reducing energy consumption and alleviating climate change. The research uses a mixed-method approach drawn from recent studies to explore the readiness, maturity and level of engagement of construction stakeholders in adopting the UK government sustainability agenda. Limited positive energy practices and sustainability regulatory awareness, combined with information provision deficiencies, form some of the key barriers to sustainable construction faced by industry. A service-oriented platform that provides integrated access to sustainability resources in the form of interactive, dynamic and user-oriented services that fully exploit latest advances in computing technologies is proposed to address these barriers. In this paper, we specifically elaborate on how a service-oriented system can be efficiently used for performing (near) real-time energy optimisation in buildings, greatly contributing to engaging construction stakeholders with sustainability practices. The solution disseminates energy efficient practices and provides support for building managers in implementing energy efficient optimisation plans. The solution is tested and validated through a number of energy efficiency scenarios developed as part of the EU FP7 SportE2 project.     

Deformation and damage upon stretching of degradable polymers (PLA and PCL)

Microstructure and plastic behavior of poly(lactic acid), PLA, and poly(ε-caprolactone), PCL, are investigated. The injected molded specimens are analyzed as received. Thermomechanical properties are characterized by DSC and DMA and crystalline structure by WAXS. The results show that PLA samples are weakly crystalline (14 wt%) and that amorphous phase is glassy at room temperature. The PCL samples exhibit higher crystallinity (53 wt%) and contain a rubber-like amorphous phase. Mechanical behavior is investigated by means of novel video-controlled materials testing system specially developed to assess true stress vs. true strain curves and to record the volume changes upon stretching. While tested at 50 °C, PLA undergoes extensive plastic deformation with a dramatic yield softening followed by a progressively increasing strain hardening. Volume strain, which characterizes deformation damage, increases steadily over the whole plastic stage until reaching 0.27 for an axial strain of 1, 4. For its part, PCL exhibits at 23 °C a much progressive plastic response with a soft yield point, no softening, and moderate strain hardening at large strain. Volume change is delayed until axial strain reaches 0.4. Subsequent damage grows very quickly, eventually reaching 0.2 for an ultimate strain of 1, 3. Results are discussed on the basis of microscopic damage mechanisms observed in the stretched state.     

Wettability determination of core samples through visual rock and fluid imaging during fluid injection

Reservoir rock wettability is a key factor in oil recovery, as it controls the location, flow, and distribution of reservoir fluids. However, proper assessment of wettability is not an easy task and provides a number of challenges. Wettability is in parts determined by the history of the oil reservoir through mechanisms such as aging and fouling. Hence direct measurements on freshly exposed rock surfaces (e.g. on core plugs) are critical and might not represent the true wettability within the sample. We present a new and fast method for wettability determination based on the optical observation of injected fluids, which allows for wettability determination independent from the surface wettability state of the sample. Fluid behavior within the boundaries of the capillary regime is driven by capillary forces and thus by wettability, which is exploited for our method. We show that a combined optical white-light and fluorescence imaging technique provides excellent contrast for reliable observations. Based on this imaging technique, we successfully distinguish core samples with different internal wettability, independent of their surface state.     

Value creating construction virtual teams: A case study in the construction sector

The research explores factors influencing knowledge value creation of virtual teams in the construction industry. Collectiveness and conscientiousness emerge as important socio-cultural enablers for value creation. Collectiveness represents the degree of cohesiveness and social relationships between virtual team members and conscientiousness represents an awareness of the situation and avoidance of uncertainty and risk by team members. Moreover, technology assets, human networks, social capital, intellectual capital, and change management are identified as essential ingredients that have the potential to ensure effective knowledge value creation.