Stream detection for LiDAR digital elevation models from a forested area

Airborne Laser Swath Mapping instrument technology and subsequent algorithm advances have made it possible over the last few years to map the Earth's surface and land cover at unprecedented resolution. The ability of Airborne Laser Swath Mapping technology to densely sample ground elevations beneath forest canopies is particularly important because forested watersheds have traditionally been difficult to study with remote sensing techniques. The extraction of stream networks from digital elevation models (DEMs) plays a fundamental role in modelling local and spatially distributed hydrological processes. Our approach, based on an encoding of mathematical morphological operators, is shown to systematically and accurately extract stream channel locations, forms and incipient incisions in a forested watershed. The accuracy of the method is verified using a set of error measures over simulated terrain and also over real terrain where the site was manually surveyed.     

A vector-multiplication dominated parallel algorithm for the computation of real eigenvalue spectra

In order to exploit effectively the power of array and vector processors for the numerical solution of linear algebraic problems it is desirable to express algorithms principally in terms of vector and matrix operations. Algorithms which manipulate vectors and matrices at component level are best suited for execution on single processor hardware. Often, however, it is difficult, if not impossible, to construct efficient versions of such algorithms which are suitable foe execution on parallwl hardware. A method for computing the eigenvalues of real unsymmetric matrices with real eigenvalue spectra is presented. The method is an extension of the one described in ref. [1]. The algorithm makes heavy use of vector inner product evaluations. The manipulation of individual components of vectors and matrices is kept to a minimum. Essentially, the method involves the construction of a sequence of biorthogonal transformation matrices the combined effect of which is to diagonalise the matrix. The eigenvalues of the matrix are diagonal elements of the final diagonalised form. If the eigenvectors of the matrix are also required the algorithm may be extended in a straightforward way. The effectiveness of the algorithm is demonstrated by an application of sequential version to several small matrices and some comments are made about the time complexity of the parallel version.     

Increasing the maintenance of self-control treatments through faded counselor contact and high information feedback.

In many counseling studies, follow-up data indicate that clients have abandoned treatment procedures and their initial progress has deteriorated. The present experiment explored 2 procedures for enhancing treatment maintenance: fading counselor contact and increasing information feedback. 97 volunteer college students concerned about academic underachievement participated. A bibliocounseling system was employed involving 4 behavioral self-control groups, a study skills advice group, and a no-treatment control group. The design also included a no-contact control group of 21 nonvolunteers. Grade and questionnaire results showed faded contact was superior to steady contact for enhancing treatment maintenance. Increasing information feedback about treatment effectiveness did not affect maintenance. Self-control and study skills advice groups were superior to control groups. Results suggest that counselors should consider fading their contact with clients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructure and elastic properties of sintered hydroxyapatite

The paper focuses on the dependence of microstructure and elastic properties of sintered hydroxyapatite on the processing parameters. Several specimens were sintered in conventional furnace at various temperatures. Elastic moduli were measured ultrasonically and information about the microstructure was recovered from these data and then verified by analysis of microphotographs. It was obtained that the average shape of pores becomes more round as the sintering temperature increases. That leads, in particular, to higher fracture toughness of the material since the stress concentration near pores is reduced.     

Measuring the flow experience of gamers: An evaluation of the DFS-2

One element of growing interest in the video gaming literature is the flow state, which is a pleasing and engaging experience commonly reported by players of games. As such, there are many different measures and methods that seek to quantify the flow experience. The present work examined whether a common measure of flow, the Dispositional Flow Scale-2 (DFS-2), was valid to use in the gamer population. We initially collected data from 762 undergraduate students. Of these, 314 qualified as “gamers” and were included in our analysis. Participants completed the DFS-2 based on their personal gaming experiences and the data was subjected to factor analysis. We did not find the DFS-2 to be an adequate measure of flow for the game experience and that continued examination of the construct and measure refinement is necessary.     

Sourcing Organic Materials for Pit Lake Bioremediation in Remote Mining Regions

Pit lakes formed by open-cut mining may have poor water quality as a result of Acidic and Metalliferous Drainage (AMD). Water quality remediation treatments that enhance naturally occurring alkalinity-generating processes (bioremediation) can be used to remediate these water quality problems. Microbially-mediated sulfate reduction using carbon as an electron donor is one approach that shows promise. Carbon amendment can be bulk organic materials, which are often cheap or free. This study investigated a process for determining what organic materials were best for in situ pit lake AMD bioremediation in a remote mining region. Following a literature review identifying how different organic materials facilitated sulfate reduction in AMD waters, we evaluated availability and costs of acquiring and transporting these materials to a typical remote mine pit lake. We found that those sourcing organic materials should focus on a mixture of sewage sludge and green waste, which are commonly available from mining camps/service towns and from land clearing operations.     

Column breakthrough studies for the removal and recovery of phosphate by lime-iron sludge: Modeling and optimization using artificial neural network and adaptive neuro-fuzzy inference system

Increases in the treatment of water to meet the growing water demand ultimately result in unmanageable quantities of residuals, the handling, and disposal of which is a major environmental issue. Consequently, research into beneficial reuse of water treatment residuals continues unabated. This study investigated the applicability of lime-iron sludge for phosphate adsorption by fixed-bed column adsorption. Laboratory-scale experiments were conducted at varying flow rates and bed depths. Fundamental and empirical models(Thomas, Yan,Bohart-Adams, Yoon-Nelson, and Wolboroska) as well as artificial intelligence techniques(Artificial neural network(ANN) and Adaptive neuro-fuzzy inference system(ANFIS)) were used to simulate experimental breakthrough curves and predict column dynamics. Increase in flow rate resulted in reduced adsorption capacity.However, adsorption capacity was not affected by bed depth. ANN was superior in predicting breakthrough curves and predicted breakthrough times with high accuracy(R~20.9962). Na OH(0.5 mol·L~(-1)) was successfully used to regenerate the adsorption bed. After nine cyclic adsorption/desorption runs, only a marginal decrease in adsorption and desorption efficiencies of 10% and 8% respectively was observed. The same regenerate Na OH solution was reused for all desorption cycles. After nine cycles the eluent desorbed a total of 1550 mg phosphate exhibiting potential for further reuse.     

Experimental demonstration of meso-scale carbon nanotube self-assembled tube structures

In addition to numerous other properties of interest, carbon nanotubes (CNT) promise to form a basis for new materials of extraordinary strength owing mainly to the very high carbon–carbon bond energies and their unique tubular structure at the molecular scale. In the area of materials development, the guiding concept of bio-inspired hierarchical structures combined with controlled fabrication at multiple scales has the potential to result in substantially improved mechanical performance. Here we show examples of a multiple-scale self-assembled tube structure, which are themselves composed of multi-wall CNTs, while also demonstrating some important aspects of their nucleation and growth. These hierarchical and self-assembled objects strongly indicate the feasibility of controlled synthesis of macroscopic CNT structures and CNT-reinforced materials for use in various engineering applications. These applications could encompass the areas of structures, thermal transfer, electronics, fluid dynamics, and micro-fluidics.     

Point-of-need quantitative detection of trihalomethanes in environmental water samples using a highly sensitive and selective fiber-based preconcentration system

Drinking water—a vital part of our ecosystem—is often exposed to contamination through industrialization. Halogenated compounds, for example, trihalomethanes (THMs), are among the most common contaminants, being by-products of water chlorination/treatment. The carcinogenic and health effects of these compounds have motivated scientists to work on the accurate detection of THMs down to 80 ppb in treated water. Here, a superhydrophobic syndiotactic polypropylene (sPP) nanofiber mat is used to preconcentrate THMs in environmental water samples, and subsequently, detect them using a well-known colorimetric reaction chemistry. The reaction chemistry yields a visible red/pink chromophore under visible light absorption. This reaction occurs when the preconcentrated THM becomes trapped in the liquid phase of the reaction chemistry, on the surface of the sPP fibers. This fiber mat is electrospun in a way which results in a large water contact angle >150°—allowing the working sensitivity of the reaction chemistry to be heightened and lowering the detection limit. The resulting color change can be analyzed via a simple quantitative color intensity analysis utilizing widely-available software, measuring the THM content in water as low as 0.8 ppb. This cost-effective and selective method was incorporated into a portable device, enabling on-site users to evaluate the quality of drinking water.