RECYTRACK is a 3.5 year project granted by the European Commission through LIFE＋ 2010 program. The overall objective of the project is to demonstrate the environmental benefits and technical feasibility of the implem...RECYTRACK is a 3.5 year project granted by the European Commission through LIFE＋ 2010 program. The overall objective of the project is to demonstrate the environmental benefits and technical feasibility of the implementation of an elastomeric eco-friendly material made of end-of-life tires with resin for railway applications. Within the project, AV Ingenieros jointly with LEAM, carries out the study of the vibration behavior of the eco-friendly material, which will be applied as a mat for ballasted tracks as well as an isolated block system for slab tracks. Firstly, an analytical model capable to predict the efficiency of the eco-friendly material as a vibration mitigation measure has been developed. Subsequently, and after the implementation of the eco-friendly solutions in real railway infrastructures, its vibration behavior will be measured and validated through in situ measurements during regular service. In this paper the analytical model is defined, the elastomeric material dynamic experimental characterization is described and the under ballast mat Insertion Loss is calculated for two different soil stiffness.展开更多
In recent years, with the growing concerns on environmental protection and human health, new materials, such as lead-free piezoelectric materials, have received increasing attention. So far, three types of lead-free p...In recent years, with the growing concerns on environmental protection and human health, new materials, such as lead-free piezoelectric materials, have received increasing attention. So far, three types of lead-free piezoelectric systems have been widely researched, i.e., perovskites, bismuth layer-structured ferroelectrics, and tungsten-bronze type ferroelectrics. This article presents a new type of environmental friendly piezoelectric material with simple structure, the transition-metal（TM）-doped ZnO. Through substituting Zn2＋ site with small size ion, we obtained a series of TM-doped ZnO with giant piezoresponse, such as Zno.975Vo.o250 of 170 pC/N, Zn0.94Cr0.06O of 120 pC/N, Zn0.913Mn0.0870 of 86 pC/N and Zn0.988Fe0.0120 of 127 pC/N. The tremendous piezoresponses are ascribed to the introduction of switchable spontaneous polarization and high permittivity in TM-doped ZnO, The microscopic origin of giant piezoresponse is also discussed. Substitution of TM ion with small ionic size for Zn2＋ results in the easier rotation of noncollinear TM-O1 bonds along the c axis under the applied field, which produces large piezoelectric displacement and corresponding piezoresponse enhancement. Furthermore, it proposes a general rule to guide the design of new wurtzite semiconductors with enhanced piezoresponses. That is, TM-dopant with ionic size smaller than Zn2＋ substitutes for Zn2＋ site will increase the piezoresponse of ZnO significantly. Finally, we discuss the improved per- formances of some TM-doped ZnO based piezoelectric devices.展开更多
文摘RECYTRACK is a 3.5 year project granted by the European Commission through LIFE＋ 2010 program. The overall objective of the project is to demonstrate the environmental benefits and technical feasibility of the implementation of an elastomeric eco-friendly material made of end-of-life tires with resin for railway applications. Within the project, AV Ingenieros jointly with LEAM, carries out the study of the vibration behavior of the eco-friendly material, which will be applied as a mat for ballasted tracks as well as an isolated block system for slab tracks. Firstly, an analytical model capable to predict the efficiency of the eco-friendly material as a vibration mitigation measure has been developed. Subsequently, and after the implementation of the eco-friendly solutions in real railway infrastructures, its vibration behavior will be measured and validated through in situ measurements during regular service. In this paper the analytical model is defined, the elastomeric material dynamic experimental characterization is described and the under ballast mat Insertion Loss is calculated for two different soil stiffness.
基金supported by the National Hi-tech (R&D) Program of China (Grant Nos. 2007AA03Z426 and 2009AA034001)the National Natural Science Foundation of China (Grant Nos. 50871060 and 50772055)the National Basic Research Program of China (Grant No. 2010CB832905)
文摘In recent years, with the growing concerns on environmental protection and human health, new materials, such as lead-free piezoelectric materials, have received increasing attention. So far, three types of lead-free piezoelectric systems have been widely researched, i.e., perovskites, bismuth layer-structured ferroelectrics, and tungsten-bronze type ferroelectrics. This article presents a new type of environmental friendly piezoelectric material with simple structure, the transition-metal（TM）-doped ZnO. Through substituting Zn2＋ site with small size ion, we obtained a series of TM-doped ZnO with giant piezoresponse, such as Zno.975Vo.o250 of 170 pC/N, Zn0.94Cr0.06O of 120 pC/N, Zn0.913Mn0.0870 of 86 pC/N and Zn0.988Fe0.0120 of 127 pC/N. The tremendous piezoresponses are ascribed to the introduction of switchable spontaneous polarization and high permittivity in TM-doped ZnO, The microscopic origin of giant piezoresponse is also discussed. Substitution of TM ion with small ionic size for Zn2＋ results in the easier rotation of noncollinear TM-O1 bonds along the c axis under the applied field, which produces large piezoelectric displacement and corresponding piezoresponse enhancement. Furthermore, it proposes a general rule to guide the design of new wurtzite semiconductors with enhanced piezoresponses. That is, TM-dopant with ionic size smaller than Zn2＋ substitutes for Zn2＋ site will increase the piezoresponse of ZnO significantly. Finally, we discuss the improved per- formances of some TM-doped ZnO based piezoelectric devices.
