For thermal natural ventilation, buoyancy plumes deriving from heating source make thermal stratification in room. The height difference between inlet and outlet is one of the important factors influencing thermal stratification. Taking a representative civil building with inside heating sources as the research object, using the technique of CFD, changing the height difference between inlet and outlet center, this paper gives simulation on the fluid field caused from thermal natural ventilation, analyzes the velocity field and temperature field under different simulation conditions, presents the influence rule of the height difference between inlet and outlet on thermal stratification in rooms. The results can provide a theory reference for natural ventilation system design in domestic buildings.

Considering the shortcoming of the traditional Greedy Perimeter Stateless Routing Protocol in the Vehicular Ad hoc Networks ,this paper focuses on an improved GPSR protocol based on the density of vehicle flow .This new scheme includes macro-directing algorithm , micro-forwarding strategy and the maintenance of the neighbor list.The simulation result shows that compared with the traditional GPSR protocol, the new GPSR protocol improves data packet delivery ratio, but its average end-to-end delay is slightly larger than before.

Relative humidity is an important micro-climate parameter in radiant cooling environment. Based on the human thermal comfort model, this paper studied the effect on PMV index of relative humidity, and studied the relationship of low mean radiant temperature and relative humidity, drew the appropriate design range of indoor relative humidity for radiant cooling systems.The results show that high relative humidity can compensate for the impact on thermal comfort of low mean radiant temperature, on the premise of achieving the same thermal comfort requirements. However, because of the limited compensation range of relative humidity, together with the constraints for it due to anti-condensation of radiant terminal devices, the design range of relative humidity should not be improved, and it can still use the traditional air-conditioning design standards.

Abstract. Ontology, which adds semantic information to services, is an effective tool to automatize service discovery and composition. Though service discovery systems have been developed extensively, most possible scenario would still be that all the services adhere to a single ontology. However, even in a same domain, different domain experts or users can conceptualize the same real world entities in different views which will lead to multiple domain ontologies. Therefore how to manage multi-ontology and then how to use them to annotate service are the key technologies in service discovery system. In this paper based on ISO SC32 19763-3: MFI-3 (Metamodel Framework for Interoperability: Metamodel for Ontology Registration) we discuss in detail the mechanism of multi-ontology management and annotation to enhance the service discovery. Finally a prototype of Ontology Management Platform (OMP) is realized to serves annotation.