Tribological behaviour of copper oxide nanoparticle suspension

This work presents and discusses the tribological behaviour of nanoparticle suspensions in a polyalphaolefin (PAO6). CuO nanoparticles were separately dispersed at 0.5, 1.0 and 2.0% wt. in PAO6 using an ultrasonic probe for 2 minutes. AW properties were obtained using a TE53SLIM tribometer with a block-on-ring configuration and EP properties were obtained using a Four-Ball machine according to ASTM D2783. Wear surfaces were analyzed by SEM and EDS after tests. The study led to the following conclusions: nanoparticle suspensions exhibited reductions in friction and wear compared to the base oil; CuO suspensions showed the highest friction coefficient and lowest wear per nanoparticle content of 2%; all concentrations of nanoparticles improved the EP properties of PAO6; CuO showed better results at 0.5% wt. of nanoparticles; and the antiwear mechanism of nanoparticulate additive was produced by tribo-sintering

OPTIMAL PRICING AND GRANT POLICIES FOR MUSEUMS

Considering two potential sources of income (public grants and ticket revenues),we have defined a theoretical model where the public agency is the principal and the manager of the museum is the agent. This model allows us to design the optimal contract between both sides and thus to establish the optimal values of grants, ticket prices, budget and effort applied by the manager. Furthermore, we have found a theoretical reason to explain the inelastic pricing strategy that has been found in some of the empirical research on cultural and sports economics. The main conclusion is that the optimal contract allows a Pareto optimum solution in prices that does not change if we introduce moral hazard into this relationship. This solution allows us to conclude that the public agency should regulate ticket prices in accordance with the social valuation. However, public grants and museum budgets would be affected by the existence of this problem, moving the equilibrium away from the Pareto optimum situation. In this case, even with a risk averse manager and a risk neutral public agency, grants and budgets will depend on results because higher budgets related to good results provide the main incentives to increase the manager’s level of effort. Although the focus of this paper is on museum administration, the model that we have developed can be easily generalized and applied to other institutions, such as schools, sport facilities or NGOs, which are able to raise funds directly from private (e. g. ticket revenues or membership fees) or public sources (e.g. public grants).cultural economics, grants, public prices, museums, principal- agent model

High–Speed Data Transmission Subsystem of the SEOSAR/PAZ Satellite

This paper analyzes a digital interface and bus system modeling and optimization of the SEOSAR/PAZ Earth Observation satellite. The important part of the satellite is an X–band Synthetic Aperture Radar instrument that integrates 384 Transmit/Receive Modules located in 12 antenna panels 7.5 m away from the central processor and controlled by a synchronous 10 Mbps bidirectional serial protocol. This type of mid–range point–to–multipoint transmission is affected by bit errors due to crosstalk, transmission line attenuation and impedance mismatches. The high–speed data communication network has been designed to optimize the transmission by using a simulation model of the data distribution system which takes into account the worst–case scenario and by developing a lab–scaled prototype which exhibits BER of 10-11 for an interfering signal of 10 Vpp. The result is a point–to–multipoint bidirectional transmission network optimized in both directions with optimal values of loads and equalization resistors. This high–speed data transmission subsystem provides a compact design through a simple solution

Entropy production in the early-cosmology pionic phase

We point out that in the early universe, for temperatures in the approximate interval 175-80 MeV (after the quark-gluon plasma), pions carried a large share of the entropy and supported the largest inhomogeneities. Thus, we examine the production of entropy in a pion gas, particularizing to inhomogeneities of the temperature, for which we benefit from the known thermal conductivity. We finally put that entropy produced in relaxing such thermal inhomogeneities in the broad context of this relatively unexplored phase of early-universe cosmology.Comment: 10 pages, 10 figures

Optimal assignment problem on record linkage

We present an application of the Hungarian Method, an optimal assignment graph theory algorithm, to record linkage in order to improve the disclosure risk assessment. We should note that Hungarian Method has O(n^3) complexity; three different methods are presented to reduce its computational cost