Quantitative analysis of magnetic resonance radio-frequency coilsbased on method of moments

To investigate both spectral and spatial domain characteristics of radio-frequency coils in magnetic resonance experiments, we have developed a new approach based on the method of moments. Instead of the conventional point-matching scheme, the loop testing function is used. Such a testing function decreases the complexity of computation and elevates the efficiency of simulation. With the proposed testing function incorporated with a pulse basis function based on coil geometry topology, performance of both surface coil and volume coil can be predicted with consistent results compared with experimental data     

Evaluation of Non-point Source Loads in the Reservoir Watershed using the GIS/GPS/RS Information Technologies and Numerical Models

Abstract

One of the recent concerns of reservoir eutrophication issues focuses on a fast assessment of the non-point sources pollution impact. It frequently requires an initial evaluation of the land use pattern and the reservoir assimilative capacity. This information is useful for estimating the non-point source loads, assessing the proper uses of natural resources in the watershed, and generating the essential control strategies when required. To achieve this goal, the state-of-the-art 3S information technologies, which properly integrates the skills of geographic information system (GIS), global positioning system (GPS) and remote sensing (RS), is viewed as an integrated means for reservoir land use assessment and watershed management. Substantial efforts in this study are placed upon identifying seven types of land use patterns in the watershed of the Tseng-Wen Reservoir in Southern Taiwan, which would directly assist in the required estimation of non-point sources pollution impact. With the aid of SPOT satellite images, Erdas Imagine⁰ image processing system, and ArcView⁰ GIS, the numerical model based on the export coefficient method yields an estimation of non-point source loads on a yearly basis with respect to four target constituents. These constituents of interest consist of total phosphorus (TP), total nitrogen (TN), biochemical oxygen demand (BOD), and total suspended solid (TSS). The analysis of assimilative capacity of the Tseng-Wen Reservoir based on various types of numerical models is also included for the evaluation of the eutrophication issue. Advanced management strategies with regard to the proper use of assimilative capacity of the Tseng-Wen Reservoir and the land resources in the watershed are then discussed in terms of three classified impact levels of non-point sources in the watershed. The methodology is proved practical, promising, and effective for assessing the eutrophication issue in the reservoir watershed within a short period of time     

Microstructural and chemical variation of TiO2 electrodes in DSSCs after ethanol vapour treatment

TiO₂ based dye-sensitized solar cells (DSSCs) have great potential to solve many energy challenges, however, their low energy conversion rate is still a barrier for further applications. Ethanol vapour post-treatment can improve the DSSC's conversion efficiency without changing its architecture, and a stable 2–3% improvement was found in our experiments. Microstructural and chemical factors were investigated using scanning electron microscopy and analytical electron microscopy on treated and untreated electrodes. The vapour treatment improved the porosity and surface-to-volume ratio of the TiO₂ particles, decreased electron transport loss between TiO₂ and fluorine doped tin oxide, and increased hydroxyl sites on the TiO₂ particle's surface. The modification therefore enhanced the dye uptake and dye–TiO₂ coupling, and it reduced the energy loss during the carrier transfer.     

The situational reflection of reality in activity theory and the concept of situation awareness in cognitive psychology

This article presents new data from the implementation of Activity Theory and integrates it with some concepts of cognitive psychology. The main focus is on orienting activity, which is directed to comprehending and interpreting reality as well as predicting future events' significance for the performance of present events. The concept of orienting activity is directly related to what is known as Situation Awareness (SA) in the US. However, the concept of orienting activity is broader than that of SA. Orientation and comprehension of a situation includes not only conscious and verbally logical components, but also unconscious components. The imaginative elements of the activity and the non-verbalized meaning of the situation are important in the unconscious reflection of reality. This paper describes SA as one of the important function mechanisms involved in the dynamic reflection of the situation. Other important elements of this dynamic reflection are its emotional and motivational components.     

The use of a quasi-naturalistic riding method to investigate bicyclists’ behaviors when motorists pass

The present study aimed to investigate how motorized vehicle-related factors, road-related factors, and bicyclist-related factors influenced motorists’ decisions about initial passing distances and bicyclists’ behaviors after the motorists started to pass. A quasi-naturalistic riding method was used for thirty-four participating bicyclists riding an instrumented bicycle in real traffic. The study included 1380 incidents of left-side passing by motorists and revealed that the factors studied influenced both the motorists’ initial passing distance and the bicyclists’ position (lateral distance from the passing motorists), wheel angle, and speed control behaviors while the motorists passed. Some factors were related to the motorized vehicles; for example, the initial passing distance and the mean lateral distances were smaller when motorcycles passed than when cars and small trucks passed. The bicyclists demonstrated weaker lateral stability when they were passed by buses. In addition, a longer passing time caused the bicyclists to demonstrate cautious but less stable riding behaviors. For road-related factors, a clear and longitudinal solid line separation helped to maintain a greater lateral distance between motorists and bicyclists and assist the bicyclists in riding out of the motorists’ path, maintaining a low speed, and remaining stable. Moreover, when bicyclists avoided road surface hazards, they reduced the initial passing distances that the motorists had chosen. Considering bicyclist-related factors, the motorists selected a greater initial passing distance for female bicyclists. There were also gender differences related to the bicyclists’ lateral control, and differences in road use experience may explain this gender difference. Furthermore, the bicyclists’ wheel angle, speed, and speed variation affected the motorists’ initial passing distance. The present study demonstrated that the quasi-naturalistic riding method is capable of collecting rich data concerning bicyclists’ behaviors, which could potentially be utilized in various types of studies. However, this method requires a large sample and considerable time and effort for data processing.     

Mesoporous TiO2 thin films embedded with Au nanoparticles for the enhancement of the photocatalytic properties

Mesoporous TiO₂ thin films were prepared by hydrothermal-oxidation of titanium metal thin films, which were obtained by DC magnetron sputtering technique. Gold nanoparticles, which were prepared by reduction of HAuCl₄, were embedded into the holes of the mesoporous TiO₂ films by capillary method followed by annealing in air up to 400 °C. The size of pore of TiO₂ films is about 100 nm and that of Au nanoparticles is about 10 nm in average. The morphology of the films was analyzed by field emission scanning electron microscope (FE-SEM) and scanning probe microscopes (SPMs). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of methylene blue solution are discussed. The obtained results show that the dispersion of Au nanoparticles on the mesoporous TiO2 matrix will help enhancing the photocatalytic activity with respect to pure TiO₂ under visible light irradiation.     

Detection of DNA hybridization using the near-infrared band-gap fluorescence of single-walled carbon nanotubes

We demonstrate the optical detection of DNA hybridization on the surface of solution suspended single-walled carbon nanotubes (SWNTs) through a SWNT band gap fluorescence modulation. Hybridization of a 24-mer oligonucleotide sequence with its complement produces a hypsochromic shift of 2 meV, with a detection sensitivity of 6 nM. The energy shift is modeled by correlating the surface coverage of DNA on SWNT to the exciton binding energy, yielding an estimated initial fractional coverage of 0.25 and a final coverage of 0.5. Hybridization on the nanotube surface is confirmed using Forster resonance energy transfer of fluorophore-labeled DNA oligonucleotides. This detection is enabled through a new technique to suspend SWNTs using adsorption of single-stranded DNA and subsequent removal of free DNA from solution. While the kinetics of free DNA hybridization are relatively fast (<10 min), the kinetics of the process on SWNTs are slower under comparable conditions, reaching steady state after 13 h at 25 degrees C. A second-order kinetic model yields a rate constant of k = 4.33 x 10(5) (M h)(-1). This optical, selective detection of specific DNA sequences may have applications in the life sciences and medicine as in vitro or in vivo detectors of oligonucleotides.     

Heterodyne polariscope for sequential measurements of the complete optical parameters of a multiple-order wave plate

A new heterodyne polariscope for sequential measurements of the complete optical parameters of linearly birefringent materials is proposed. A multiple-order crystalline quartz quarter-wave plate used as a sample was tested in two sequential setups. In the first setup we used an electro-optic modulator to modulate the circular heterodyne polariscope and then applied a phase-locking technique to measure the principal axis angle precisely. In the second setup, removing the first quarter-wave plate, resulted in a linear heterodyne polariscope, and again we used the phase-locking technique to extract the apparent retardance. Furthermore, by tilting the sample and placing a material of known thickness into the second setup, we determined the order, thickness, and refractive indices (ne and no) of a multiple-order wave plate by using the new algorithm. The proposed method has average absolute errors of 0.2167 degrees and 0.15% with respect to the principal axis angle and the apparent retardance, respectively. The order, thickness, and refractive indices are also in good agreement with the known sample data. In contrast to the conventional measurement schemes that could not measure more than two parameters, the proposed heterodyne polariscope uniquely measures six parameters.