Optical metamaterials are man-made composite materials constructed with nanometer-sized periodic structures containing both dielectric and metal materials. These structures can produce materials with negative index of refraction-a unique material property that does not occur naturally. The theoretical breakthroughs made in this new class of electromagnetic materials are closely linked with progress in developing physics-driven design, novel fabrication, and characterization methods. For the optical waveguiding, a perfect control of the interaction between light and matter has been brought closer by the advances in fabrication of optical metamaterials. The unusual electromagnetic properties of metamaterials are expected to enable a new generation of miniaturized passive and active optical devices based on novel optical waveguides. In developing design strategies and new concepts for such devices, it is paramount that anisotropic properties of metamaterials are considered along with their other material features. Moreover, even the ways in which common devices operate require revisions when ordinary materials in their design are replaced by anisotropic metamaterials. Therefore, these metamaterials provide a route to creating potential devices through artificially engineered structures with negative average relative permittivity and permeability. The electromagnetic response of a metamaterial can be designed to produce desired waveguide properties. One particularly interesting metamaterial device is planar metamaterial waveguide structure that has potentially exciting applications. Properties of metamaterial waveguides when the limitations arise from fabrication techniques and physical principles have been taken into account. A considerable amount of theoretical effort has also been devoted to the analysis of optical propagation through different types of metamaterial structures, including uniaxial dielectrics and indefinite media, metal-dielectric heterostructures and superlattices, as well as strongly anisotropic waveguides. This chapter will give a brief review about perspective and prospective of the metamaterial optical waveguides.

关键词：超材料光波导；光学超材料；纳米尺寸

查看摘要 索取原文[53页]

This chapter presents a low-cost, flexible lab test-bench wind farm for advanced research and education on wind turbine and wind farm design and control. The mechanical, electrical, electronic and control system design of the wind turbines, along with the dynamic models, parameters and classical pitch and torque controllers are introduced in detail. Furthermore, the study presents a variety of experiments that (a) quantifies the effect of the number of blades in the aerodynamic efficiency, (b) estimates the generator efficiency, (c) validates the rotor-speed pitch control system, (d) proves the concept of maximum power point tracking for individual wind turbines, (e) estimates the aerodynamic C_p/λ characteristics, (f) calculates the power curve, and (g) studies the effect of wind farm topology configurations on the individual and global power efficiency. The experimental results prove that the dynamics of the test-bench corresponds well with full-scale wind turbines. This fact makes the test-bench wind farm appropriate for advanced research and education in wind energy systems.

关键词：风力发电机组的设计；风力发电机组造型；涡轮参数辨识

查看摘要 索取原文[38页]

This project was an initial effort to investigate the feasibility of an instrument combining real-time atmospheric particle composition measurements using an ATOFMS (Atmospheric Time-Of-Flight Mass Spectrometer) such as those performed by Prathers group at the University of California, San Diego (UCSD) with multi-wavelength scattering measurements of the type investigated by Sorensen et al., of Kansas State University (KSU). In this Phase I effort we proposed to investigate near-angle scattering and the possibility of integration of a multi-wavelength scattering instrument into the UCSD ATOFMS. After an initial optical design and calculations, we discovered issues with the theory of measurement and with mechanical integration. Evidence emerged that the method of multi-wavelength scattering is only efficacious for spherical particles, while most atmospheric particles are non-spherical fractal aggregates. We also determined that the integration of the detector into existing ATOFMS instruments would be severely limited by volume constraints, and additional volume would require prohibitive additional pumping compared with the existing ATOFMS systems. Based on this evidence, we decided not to pursue a Phase II effort.

关键词：大气；空气治理；空气污染

查看摘要 索取原文[6页]

The objective of this project was to investigate the complex fracture of ice and understand its role within larger ice sheet simulations and global climate change. This objective was achieved by developing novel physics based models for ice, novel numerical tools to enable the modeling of the physics and by collaboration with the ice community experts. Fracture of ice is important in several fields of which the most visible and certainly the most significant is global warming. This has recently received international attention due to the collapse of some significant ice shelves. Ice fracture, however, is also important in other areas including oil and gas exploration and production within ice-infested waters, materials science research and length scales in ice, and microbiology. At the present time, ice fracture is not explicitly considered within ice sheet models due in part to large computational costs associated with the accurate modeling of this complex phenomena. However, fracture not only plays an extremely important role in regional behavior but also influences ice dynamics over much larger zones in ways that are currently not well understood. Dramatic illustrations of fracture-induced phenomena most notably include the recent collapse of ice shelves in Antarctica (e.g. partial collapse of the Wilkins shelf in March of 2008 and the diminishing extent of the Larsen B shelf from 1998 to 2002).

关键词：大气；气候变化；全球变暖

查看摘要 索取原文[31页]

Exposure assessments of open burn pits are often complicated by a lack of sampling equipment and resources. This research investigated the hypothesis of carbon dioxide (CO2) as a viable surrogate for particulate matter with diameter 8804; 2.5m (PM2.5). Large-scale solid waste combustion tests resulted in linear trends between mean PM2.5 and CO2 (R2 = 0.964 - 0.989). This pilot study demonstrates the feasibility of using CO2 as a surrogate of PM2.5 concentration as CO2 sensors potentially provide a cost-effective solution for monitoring in lieu of expensive PM instruments. It also indicates the potential reduction in particulate matter when using batch-feeding practices with burn boxes (versus open burning).

关键词：大气；空气污染；空气监控

查看摘要 索取原文[76页]

This paper presents overviews of a number of processes and applications associated with high-power, high-intensity lasers and their interactions. These processes and applications include: free electron lasers, backward Raman amplification, atmospheric propagation of laser pulses, laser driven acceleration, atmospheric N2 lasing, and remote detection of radioactivity. The interrelated physical mechanisms in the various processes are discussed.

关键词：大气；空气质量；空气治理

查看摘要 索取原文[40页]

In composites, two or more materials are combined in order to employ their individual virtues while minimizing their deficiencies. In general, these hybrid systems exhibit new chemico-physical characteristics that originate from the cooperative effect of the distinctive properties of the materials used. In its own particular way, the engineering of composite carbon-based materials through decoration with metal NanoParticles (NPs) has proved to be key for the improvement of the intrinsic properties of graphene and Carbon NanoTubes (CNTs). A plethora of methods have been employed for the controlled deposition and immobilization of metal NPs onto the CNT surface. To this end, both physical and chemical approaches have been recently developed; each offering its own strengths and weaknesses, which can then be tailored for specific applications. Here we start with an overview of the main methods used for the synthesis of these hybrid systems, with emphasis on the most meaningful examples described in the literature. Metal NP-CNT composites are highly suitable for a number of practical applications ranging from catalysis to optoelectronics to chemical and bio-sensing. The Chapter reports the main efforts carried out to date to integrate metal NP-CNT composites in high-performance nano-devices. The use of modified CNTs often proved more effective than that of pristine ones; however in some cases decoration with metal NPs leads to no improvement. This Chapter sets out to describe the mechanisms, which improve decorated CNTs or pristine CNTs according to the case involved. We conclude by considering metal filled-CNTs, a special class of metal modified-CNTs. The different approaches to filling CNTs with metal NPs are discussed; we then focus on their use as magnetic probes and microwave absorbing materials.

关键词：金属纳米粒子；碳纳米管复合材料；控制器

查看摘要 索取原文[22页]

The U.S. Geological Survey Branch of Quality Systems operates the Precipitation Chemistry Quality Assurance project (PCQA) to provide independent, external quality-assurance for the National Atmospheric Deposition Program (NADP). NADP is composed of five monitoring networks that measure the chemical composition of precipitation and ambient air. PCQA and the NADP Program Office completed five short-term studies to investigate the effects of equipment performance with respect to the National Trends Network (NTN) and Mercury Deposition Network (MDN) data quality: sample evaporation from NTN collectors; sample volume and mercury loss from MDN collectors; mercury adsorption to MDN collector glassware, grid-type precipitation sensors for precipitation collectors, and the effects of an NTN collector wind shield on sample catch efficiency.

关键词：大气；大气治理；空气健康

查看摘要 索取原文[62页]

Energy availability and long term operation are key challenges for wireless sensor networks and for all the applications where the devices are battery operated. For this reason energy harvesting is becoming very important for powering ubiquitously deployed sensor networks and mobile electronics. One of most important goal for the next generation of power supply units for standalone embedded systems is to power nearly perpetually the devices when the scavenger is exposed to reasonable environmental energy conditions. However, due to the unpredictable nature of the environmental sources, prolonged lacks of energy intake usually happen. The last frontiers of perpetual operating systems is combining different energy harvesters in a single unit and using green energy supply with high energy density as micro hydrogen fuel cells. In this paper we introduce a Smart Power Unit (SPU) for embedded system which incorporates energy harvesters from sun and wind and uses hydrogen fuel cell as alternative energy storage. The power unit can work as a long-term battery or providing serial communication to exchange power information and to perform power management. In fact the core of the SPU is an ultra low power micro controller which is in charge to do the power activities such as Maximum Power Point Tracking for the harvesters, fuel cell activation, energy prediction, adaptive power management on board, battery monitoring and communications with powered systems. Experimental results and simulations shows the high efficiency (up to 90 %) of the power conversion subsystem. Finally a real deployment in a structural health monitoring site in Switzerland shows as the energy neutral condition is achieved on field.

关键词：氢燃料电池；能源供应；永久操作系统

查看摘要 索取原文[10页]

In-cylinder blending of gasoline and diesel fuels to achieve low-temperature reactivity controlled compression ignition (RCCI) can reduce NOx and PM emissions while maintaining or improving brake thermal efficiency compared to conventional diesel combustion (CDC). Moreover, dual-fueling is able to achieve these benefits by tailoring combustion reactivity over a wider range of engine operation than is possible with a single fuel. However, the currently demonstrated range of stable RCCI combustion just covers a portion of the engine speed-load range required in several light-duty drive cycles. This means that engines must switch from RCCI to CDC when speed and load fall outside of the stable RCCI range. In this study we investigated the potential impact of RCCI on the engine-out exhaust temperature and emissions of a multimode RCCI-enabled vehicle operating over two urban and two highway driving cycles. To implement our simulations, we employed experimental RCCI/CDC engine maps combined with a standard mid-size, automatic transmission, passenger vehicle configuration details in the Autonomie vehicle simulation platform. Our results include both detailed transient and cycle-averaged engine exhaust temperature and emissions. We note the potential implications of the modified exhaust properties on catalytic emissions control and utilization of waste heat recovery on future RCCI-enabled vehicles.

关键词：大气；废气排放；空气污染

查看摘要 索取原文[11页]