Resonant second harmonics generation of the submillimeter surface wave in the semiconductor superlattice bounded by a metal

In this study, the process of the resonant second harmonics generation of the submillimeter (SM), which is of interest for design of the semiconductor frequency multipliers is evaluated. Particularly, the possibility to use the semiconductor superlattice-metal structures as an effective second harmonics generator is demonstrated.

Heating self-interaction mechanism of surface magnetoplasma waves in plasma-like medium bounded by metal

The influence of electron heating in the high-frequency surface magnetoplasma wave(SM) field on dispersion properties of the considered SM is investigated. High frequency SM propagate at the interface between a plasma like medium with a finite electrons pressure and a metal. The nonlinear dispersion relation for the SM is derived and investigated.

Two-channel waveguide modulator based on surface wave propagating in a semiconductor-metal thin-film structure

The results of theoretical investigations of two-channel waveguide modulator based on Surface Wave (SW) propagation are presented. The structure studied consists of two n-type semiconductor waveguide channels separated from each other by a dielectric gap and coated by a metal. The SW propagates at the semiconductor-metal interface across an external magnetic field which is parallel to the interface. An external dc voltage is applied to the metal surface of one channel to provide a small phase shift between two propagating modes. In a coupled mode approximation, two possible regimes of operation of the structure, namely as a directional coupler and as an electro-optical modulator, are considered. Our results suggest new applications in millimeter and submillimeter wave solid-state electronics and integrated optics.

Microwave gas discharge produced and sustained by a surface wave propagating along a cylindrical metal antenna with a dielectric coating

The structure of a microwave gas discharge produced and sustained by a surface wave (SW) propagating along a cylindrical metal antenna with a dielectric coating is studied. The SW that produces and sustains the microwave gas discharge propagates along an external magnetic field and has an eigenfrequency in the range between the electron cyclotron and electron plasma frequencies. The presence of a dielectric (vacuum) sheath region separating the antenna from the plasma is assumed. The spatial distributions of the produced plasma density, electromagnetic fields, energy flow density, phase velocity and reverse skin depth of the SW are obtained analytically and numerically.

Finite-SNR diversity-multiplexing trade-off of inter-vehicular cooperative diversity protocols

The finite-signal-to-noise ratio (SNR) diversity-multiplexing trade-off (DMT) of cooperative diversity protocols are investigated in vehicular networks based on cascaded Rayleigh fading. Lower bounds of DMT at finite SNR for orthogonal and non-orthogonal protocols are derived. The results showcase the first look into the achievable DMT trade-off of cooperative diversity in volatile vehicular environments. It is shown that the diversity gains are significantly suboptimal at realistic SNRs.

CFD simulations of flow and heat transfer through the porous interface of a metal foam heat exchanger

This paper offers numerical modelling of a waste heat recovery system. A thin layer of metal foam is attached to a cold plate to absorb heat from hot gases leaving the system. The heat transferred from the exhaust gas is then transferred to a cold liquid flowing in a secondary loop. Two different foam PPI (Pores Per Inch) values are examined over a range of fluid velocities. Numerical results are then compared to both experimental data and theoretical results available in the literature. Challenges in getting the simulation results to match those of the experiments are addressed and discussed in detail. In particular, interface boundary conditions specified between a porous layer and a fluid layer are investigated. While physically one expects much lower fluid velocity in the pores compared to that of free flow, capturing this sharp gradient at the interface can add to the difficulties of numerical simulation. The existing models in the literature are modified by considering the pressure gradient inside and outside the foam. Comparisons against the numerical modelling are presented. Finally, based on experimentally-validated numerical results, thermo-hydraulic performance of foam heat exchangers as waste heat recovery units is discussed with the main goal of reducing the excess pressure drop and maximising the amount of heat that can be recovered from the hot gas stream.

Regional trade-offs between mine water and energy use : a water treatment case study

The mining industry faces concurrent pressures of reducing water use, energy consumption and greenhouse gas (GHG) emissions in coming years. However, the interactions between water and energy use, as well as GHG e missions have largely been neglected in modelling studies to date. In addition, investigations tend to focus on the unit operation scale, with little consideration of whole-of-site or regional scale effects. This paper presents an application of a hierarchical systems model (HSM) developed to represent water, energy and GHG emissions fluxes at scales ranging from the unit operation, to the site level, to the regional level. The model allows for the linkages between water use, energy use and GHG emissions to be examined in a fl exible and intuitive way, so that mine sites can predict energy and emissions impacts of water use reduction schemes and vice versa. This paper examines whether this approach can also be applied to the regional scale with multiple mine sites. The model is used to conduct a case study of several coal mines in the Bowen Basin, Australia, to compare the utility of centralised and decentralised mine water treatment schemes. The case study takes into account geographical factors (such as water pumping distances and elevations), economic factors (such as capital and operating cost curves for desalination treatment plants) and regional factors (such as regionally varying climates and associated variance in mine water volumes and quality). The case study results indicate that treatment of saline mine water incurs a trade-off between water and energy use in all cases. However, significant cost differences between centralised and decentralised schemes can be observed in a simple economic analysis. Further research will examine the possibility for deriving model up-scaling algorithms to reduce computational requirements.

Hybrid polymer/metal nanoparticles with surface enhanced raman tracking for potential use in nanomedicine

This project was a preliminary step towards the development of novel methods for early stage cancer diagnosis and treatment. Diagnostic imaging agents with high Raman signal enhancement were developed based on tailored assemblies of gold nanoparticles, which demonstrated potential for non-invasive detection from deep under the skin surface. Specifically designed polymers were employed to assemble gold nanoparticles into controlled morphologies including dimers, nanochains, nanoplates, globular and core-satellite nanostructures. Our findings suggest that the Raman enhancement is strongly dependent on assembly morphology and can be tuned to adapt to the requirements of the diagnostic agent.

A study of the effects metal residues in poly(9,9-dioctylfluorene) have on field-effect transistor device characteristics

The amount of metal residues from organometallic reagents used in preparation of poly(9,9-dioctylfluorene) by palladium catalysed Suzuki and nickel-induced Yamamoto polycondensations have been determined, and their effect upon the behaviour of the polymer in field-effect transistors (FETs) has been measured. The metal levels from material polymerised by Suzuki method were found to be much higher than from that made by the Yamamoto procedure. Simple treatment of the polymers with suitable metal trapping reagents lowered the metal levels significantly, with EDTA giving best results for nickel and triphenylphosphine for palladium. Comparison of the behaviour of FETs using polyfluorenes with varying levels of metal contamination, showed that the metal residues have little effect upon the mobility values, but often affect the degree of hysteresis, possibly acting as charge traps. Satisfactory device performances were obtained from polymer with palladium levels of 2000 μg/g suggesting that complete removal of metal residues may not be necessary for satisfactory device performance.

The effect of trade openness on deforestation: empirical analysis for 142 countries

This study explores the effect of trade openness on deforestation. Previous studies do not find a clear effect of trade openness on deforestation. We use updated data on the annual rate of deforestation for 142 countries from 1990 to 2003, treat trade and income as endogenous, and take into consideration an adjustment process by applying a dynamic model. We find that an increase in trade openness increases deforestation for non-OECD countries while slowing down deforestation for OECD countries. There is a possibility that both capital-labor and environmental-regulation effects have a negative impact on deforestation in developing countries, whereas the opposite holds in developed countries. © 2012 Springer Japan.

Testing the international linkage in the platinum-group metal futures markets

This study tests whether an international market exists in the platinum-group metal (PGM) futures markets. For this purpose, we tested the law of one price (LOP) and the causality between the U.S. and Japanese platinum and palladium futures markets. We also performed the test when structural breaks are considered. Long-run price relationships were found in both platinum and palladium markets but the LOP only sustained in the palladium market. The causality test revealed that it is the U.S. market that leads the price to transmit information between the U.S. and Japanese markets. Structural breaks had large impacts on the test results, suggesting that incorporating breaks is important when investigating the international price linkage in the PGM futures markets.

The impacts of exchange rate volatility on vegetable trade flows

Trade flows of commodities are generally affected by the principles of comparative advantage in a free trade. However, trade flows might be enhanced or distorted not only by various government interventions, but also by exchange rate fluctuations among others. This study applies a commodity-specific gravity model to selected vegetable trade flows among Organization for Economic Co-operation and Development (OECD) countries to determine the effects of exchange rate uncertainty on the trade flows. Using the data from 1996 to 2002, the results show that, while the exchange rate uncertainty significantly reduces trade in the majority of commodity flows, there is evidence that both short- and long-term volatility have positive effect on trade flows of specific commodities. This study also tests the regional preferential trade agreements such as the North American Free Trade Agreement (NAFTA), the Asia-Pacific Economic Cooperation (APEC) and the EU, and their different effects on commodities.

Productivity measures and effects from subsidies and trade : an empirical analysis for Japan's forestry

Several techniques have been proposed in the literature to measure productivity. While allowing for inefficiency of the production unit, we provide a methodological comparison of alternative approaches to measure total factor productivity. This article evaluates the effects of unintended policy outcomes such as government subsidies and foreign trade. Empirically, we analyse the forest productivity of timber in Japan by using panel data on 46 regions. The results suggest substantial variation in productivity between these two techniques although average trends are similar. We find that subsidies impede competition since the government is ready to rescue a loss-making firm with subsidies rather than allow it to close. In contrast, trade is shown to have positive effects on productivity.

Does trade openness improve environmental quality?

The literature on trade openness, economic development, and the environment is largely inconclusive about the environmental consequences of trade. This study treats trade and income as endogenous and estimates the overall impact of trade openness on environmental quality using the instrumental variables technique. We find that whether or not trade has a beneficial effect on the environment varies depending on the pollutant and the country. Trade is found to benefit the environment in OECD countries. It has detrimental effects, however, on sulfur dioxide (SO2) and carbon dioxide (CO2) emissions in non-OECD countries, although it does lower biochemical oxygen demand (BOD) emissions in these countries. We also find the impact is large in the long term, after the dynamic adjustment process, although it is small in the short term.

Trade-induced technological change : analyzing economic and environmental outcomes

We analyze how changes in trade openness are related to induced technological innovations that are not only GDP increasing but also pollution saving. Our model includes by-products of carbon dioxide and sulfur dioxide emissions. We estimate a directional distance function for 76 countries over the period 1963-2000 to measure exogenous and trade-induced technological change. On average, we find substantial trade-induced technological progress, and its magnitude is about one third of the overall technological change. The trade-induced technological changes, however, are GDP reducing and pollution increasing. Empirically, we find that increased trade openness correlates to increased pollution.