6,622 research outputs found
Polluting production â environmentally sound alternatives; A general model of production externalities
With the determination of principal parameters of producing and pollution abatement technologies, this paper quantifies abatement and external costs at the social optimum and analyses the dynamic relationship between technological development and the above-mentioned costs. With the partial analysis of parameters, the paper presents the impacts on the level of pollution and external costs of extensive and intensive environmental protection, market demand change and product fees, and not environmental protection oriented technological development. Parametrical cost calculation makes the drawing up of two useful rules of thumb possible in connection with the rate of government in-terventions. Also, the paradox of technological development aiming at intensive environmental protection will become apparent
Temperature-Induced Shape Memory Characteristics of Epoxy Resin-Based Fabric-Reinforced Composites
Shape memory characteristics of woven glass and carbon fiber fabric reinforced epoxy resin-based composites were assessed in bending mode using a dynamic mechanical analyzer. The reinforcement strongly improved the recovery stress but impaired the bending deformability. Composites with asymmetric fabric lay-up showed better performance when the reinforced section experienced local tension than compression during flexural loading
Microclimate simulation of climate change impacts in a maize canopy
Effects of possible climate modification on maize plant features have been evaluated by using the simulation model of Goudriaan for local climatic conditions and locally measured plant characteristics. Moderate climate modifications were hypothesized. According to the purpose of detecting local impacts of climate change, researches were made on the microclimate of maize canopies. In the energy transport of the plant stand, no shift has been experienced to the direction of the latent heat as it was expected because of the effect of warming up and decrease of precipitation. The changes of stomatal resistance and inside canopy air temperature suggested that the natural water supply will probably not cover the water demand of the plant, if the climate change is more intensive, therefore farmers must prepare to irrigated cultivation and to apply different agro-technical methods to save the water supplies of the ground
Resonant relaxation in globular clusters
Resonant relaxation has been discussed as an efficient process that changes
the angular momenta of stars orbiting around a central supermassive black hole
due to the fluctuating gravitational field of the stellar cluster. Other
spherical stellar systems, such as globular clusters, exhibit a restricted form
of this effect where enhanced relaxation rate only occurs in the directions of
the angular momentum vectors, but not in their magnitudes; this is called
vector resonant relaxation (VRR). To explore this effect, we performed a large
set of direct N-body simulations, with up to 512k particles and ~500 dynamical
times. Contrasting our simulations with Spitzer-style Monte Carlo simulations,
that by design only exhibit 2-body relaxation, we show that the temporal
behavior of the angular momentum vectors in -body simulations cannot be
explained by 2-body relaxation alone. VRR operates efficiently in globular
clusters with . The fact that VRR operates in globular clusters may
open way to use powerful tools in statistical physics for their description. In
particular, since the distribution of orbital planes relaxes much more rapidly
than the distribution of the magnitude of angular momentum and the radial
action, the relaxation process reaches an internal statistical equilibrium in
the corresponding part of phase space while the whole cluster is generally out
of equilibrium, in a state of quenched disorder. We point out the need to
include effects of VRR in Monte Carlo simulations of globular clusters.Comment: Submitted to Ap
Shape memory performance of asymmetrically reinforced epoxy/carbon fibre fabric composites in flexure
In this study asymmetrically reinforced epoxy (EP)/carbon fibre (CF) fabric composites were prepared and their shape memory properties were quantified in both unconstrained and fully constrained flexural tests performed in a dynamic mechanical analyser (DMA). Asymmetric layering was achieved by incorporating two and four CF fabric layers whereby setting a resin- and reinforcement-rich layer ratio of 1/4 and 1/2, respectively. The recovery stress was markedly increased with increasing CF content. The related stress was always higher when the CF-rich layer experienced tension load locally. Specimens with CF-rich layers on the tension side yielded better shape fixity ratio, than those with reinforcement layering on the compression side. Cyclic unconstrained shape memory tests were also run up to five cycles on specimens having the CF-rich layer under local tension. This resulted in marginal changes in the shape fixity and recovery ratios
- âŠ