Fluctuation-induced tunneling conduction through RuO2_2 nanowire contacts

A good understanding of the electronic conduction processes through nanocontacts is a crucial step for the implementation of functional nanoelectronic devices. We have studied the current-voltage ($I$-$V$) characteristics of nanocontacts between single metallic RuO$_2$ nanowires (NWs) and contacting Au electrodes which were pre-patterned by simple photolithography. Both the temperature behavior of contact resistance in the low-bias voltage ohmic regime and the $I$-$V$ curves in the high-bias voltage non-ohmic regime have been investigated. We found that the electronic conduction processes in the wide temperature interval 1--300 K can be well described by the fluctuation-induced tunneling (FIT) conduction theory. Taken together with our previous work (Lin {\it et al.}, Nanotechnology {\bf 19}, 365201 (2008)) where the nanocontacts were fabricated by delicate electron-beam lithography, our study demonstrates the general validity of the FIT model in characterizing electronic nanocontacts.Comment: 6 pages, 5 figure

Partonic Effects in Heavy Ion Collisions at RHIC

Effects of partonic interactions in heavy ion collisions at RHIC are studied in a multiphase transport model (AMPT) that includes both initial partonic and final hadronic interactions.It is found that a large parton scattering cross section is needed to understand the measured elliptic flow of pions and two-pion correlation function.Comment: 10 pages, 5 figures, Workshop on Quark and Hadron Dynamics, Budapest, Hungary, March 3-7, 200

Effective hadronic Lagrangian for charm mesons

An effective hadronic Lagrangian including the charm mesons is introduced to study their interactions in hadronic matter. Using coupling constants that are determined either empirically or by the SU(4) symmetry, we have evaluated the absorption cross sections of $J/\psi$ and the scattering cross sections of $D$ and $D^*$ by $\pi$ and $\rho$ mesons.Comment: 5 pages, 4 eps figures, presented at Strangeness 2000, Berkeley. Uses iopart.cl

Indoor mould growth prediction using coupled computational fluid dynamics and mould growth model

This study investigates, using in-situ and numerical simulation experiments, airflow and hygrothermal distribution in a mechanically ventilated academic research facility with known cases of microbial proliferations. Microclimate parameters were obtained from in-situ experiments and used as boundary conditions and validation of the numerical experiments with a commercial computational fluid dynamics (CFD) analysis tool using the standard k–ε model. Good agreements were obtained with less than 10% deviations between the measured and simulated results. Subsequent upon successful validation, the model was used to investigate hygrothermal and airflow profile within the shelves holding stored components in the facility. The predicted in-shelf hygrothermal profile was superimposed on mould growth limiting curve earlier documented in the literature. Results revealed the growth of xerophilic species in most parts of the shelves. The mould growth prediction was found in correlation with the microbial investigation in the case-studied room reported by the authors elsewhere. Satisfactory prediction of mould growth in the room successfully proved that the CFD simulation can be used to investigate the conditions that lead to microbial growth in the indoor environment

Revisiting individual and group differences in thermal comfort based on ASHRAE database

Different thermal demands and preferences between individuals lead to a low occupant satisfaction rate, despite the high energy consumption by HVAC system. This study aims to quantify the difference in thermal demands, and to compare the influential factors which might lead to those differences. With the recently released ASHRAE Database, we quantitatively answered the following two research questions: which factors would lead to marked individual difference, and what the magnitude of this difference is. Linear regression has been applied to describe the macro-trend of how people feel thermally under different temperatures. Three types of factors which might lead to different thermal demands have been studied and compared in this study, i.e. individual factors, building characteristics and geographical factors. It was found that the local climate has the most marked impact on the neutral temperature, with an effect size of 3.5 °C; followed by country, HVAC operation mode and body built, which lead to a difference of more than 1 °C. In terms of the thermal sensitivity, building type and local climate are the most influential factors. Subjects in residential buildings or coming from Dry climate zone could accept 2.5 °C wider temperature range than those in office, education buildings or from Continental climate zone. The findings of this research could help thermal comfort researchers and designers to identify influential factors that might lead to individual difference, and could shed light on the feature selection for the development of personal comfort models

The effects of protected beams and their connections on the fire resistance of composite buildings

According to full-scale fire tests, it is noticed that tensile membrane action within the concrete floor slabs plays an important role in affecting the fire resistance of composite buildings. It is well known that the development of tensile membrane actions relies on the vertical support along the edges of the slab panel. However, there is at present a lack of research into the influence of vertical supports on the tensile membrane actions of the floor slabs. In this paper, the performances of a generic three dimensional 45m x 45m composite floor subjected to ISO834 Fire and Natural Fire are investigated. Different vertical support conditions and three steel meshes are applied in order to assess the impact of vertical supports on tensile membrane action of floor slabs. Unlike other existing large scale modelling which assumes the connections behave as pinned or rigid for simplicity, two robust 2-node connection element models developed by the authors are used to model the behaviour of end-plate and partial end-plate connections of composite structures under fire conditions. The impact of connections on the 3D behaviour of composite floor is taken into consideration. The load-transfer mechanisms of composite floor when connections fail due to axial tension, vertical shear and bending are investigated. Based on the results obtained, some design recommendations are proposed to enhance the fire resistance of composite buildings

Prospect of Making Ceramic Shell Mold by Ceramic Laser Fusion

Manufacturing prototypical castings by conventional investment casting not only takes several weeks, but also is prohibitively expensive. Z Corporation in USA, EOS GmbH and IPT in Germany employ the techniques of 3DP and SLS respectively to make directly ceramic shell molds for metal castings. Although those techniques dramatically reduce time expenditure and production cost, each layer cannot be thinner than 50 µm because of using powder to pave layers. The dimensional accuracy and roughness of the castings still cannot meet the specification of precision casting. Therefore, in this paper the ceramic laser fusion (CLF) was used to pave layers. Each layer can be thinner than 25 µm, so that the step effect can be diminished and the workpiece surface can be smoother; drying time will be shortened dramatically. Moreover, the inherent solid-state support formed by green portion has the capability of preventing upward and downward deformation of the scanned cross sections. In order to make shell mold which meets the roughness requirement (Rq=3.048µm) of the precision casting, following issues have to be further studied: (1) design a proper ceramic shell mold structure, (2) design a paving chamber for paving a complete green layer which can be easily collapsed, (3) cut down drying time, (4) optimize laser scanning process parameters with the smallest distortion, (5) eliminate sunken area, (6) reduce layer thickness to less than13µm, (7) control power to guarantee the energy uniformly absorbed by workpiece, and (8) develop a method which can directly clean green portion in cavity from gate.Mechanical Engineerin