An investigation of a viscous lithographic developer

The photographic and physical properties of viscous lith developers have been investigated. Developers thickened with hydroxyethylcellulose (Hercules Natrasol 250 HR) afforded the optimum characteristics of ease of mixing and pseudoplastic behavior. Photographically, viscous lith developers demonstrate performance in many ways similar to non-viscous formulas. Characteristically, the developers show great sensitivity to changes in pH, and changes in HQ, bromide, and sulfite concentrations. However, viscous lith developers are inherently 0.2 log H lower in photographic activity than comparable non-viscous developers. Furthermore, viscous developers are characterized by low contrast in highlight (negative) areas of halftone reproduction. Large dot area (90%) images show poor dot quality. The lower activity is easily compensated for by changes in time and/or temperature. Also, with adjustments in constituent concentrations, the dot quality may be improved. However, no method was found to regain halftone reproduction contrast. Changes in viscosity per se impart no photographic effects. The photographic dissimilarities between viscous and nonviscous lith formulas are caused by agitation differences. This is demonstrated using still development techniques with non-viscous developer

Geographical information systems and remote sensing methods in the estimation of potential dew volume and its utilization in the United Arab Emirates

In a fast growing region of Middle East and with rapid depletion of fossil groundwater, possibilities for dew utilization as a limited renewable water resource play an important role in the water management of the United Arab Emirates. Despite projected changes in air temperature and rainfall, geographical and topographical features of the UAE show some potential for dew harvesting, mostly at the altitudes higher than 1000 m and some isolated oasis areas. With the help of geographical information system (GIS), remote sensing, and numerical and theoretical methods, approximate volumes of dew were estimated. Meteorological data was inputted together with theoretical and numerical calculations into grids by using pixelization processes. Methods such as zonal statistics, kriging, semi-kriging, and interpolation were implemented through GIS software. Another method used in this research is supervised classification and normalized difference vegetation index (NDVI) which is being determined by means of software IDRISI terra set. After finishing all the proposed methods applied in this research, four belts of potential dew use were presented. The Arabian Desert in the territory of the United Arab Emirates has no potential for dew utilization. The zone close to the oases has very low possibility of dew use. The hilly-mountainous area between 500 and 800 m.a.s.l. has medium possibility for dew use. There is a high possibility for dew use on mountain Al Hajar, occupying the area higher than 800 m; 1.3% of the whole country’s territory has excellent potential for dew use. In this part of the country, theoretically, it is possible to use dew for farming and partial watering. Experimental study together with GIS, remote sensing, and numerical analysis may extend knowledge about dew properties. Although this research includes theoretical calculations of dew utilization and has some limitations, it still presents a new insight into climate cycles in this part of the Arabian Peninsula and a way to understand them better

3D Printed Carbon Fiber Electric Mountain Bike Frame

3D printing of carbon fiber composites has been a developing technology for about 5 years, and in this time, Arevo Labs has established itself as a leader in the field. Our team joined forces with Arevo, who sponsored our project as we showcased their new, innovative carbon fiber manufacturing process. To do so, we focused on the conceptual design, analysis, assembly, and material testing of an electric mountain-bike frame printed with Arevo’s continuous carbon fiber printing technology. Our bike consists of the main frame and a chain stay subsystem, which connects the rear wheel to the rest of the frame and interfaces with a suspension system. Understanding how the capabilities of the printer, the properties of the materials, and the typical loading scenarios experienced by mountain bikes all worked together was paramount in analysis, simulation, and design optimization and iteration. Thus, the focus of this project is to design a mountain bike capable of withstanding typical loading patterns with a high level of safety. Further, the team aimed to optimize a bike frame which used the minimal amount of material necessary to reduce weight and cost for the user

Modeling the Spatially Varying Water Balance Processes in a Semi- Arid Mountainous Watershed of Idaho

Mountainous watersheds in semi-arid regions are complex hydrologic systems. To critically evaluate the hydrological processes, high resolution spatio-temporal information is necessary. Also, calibrating and validating a watershed-scale model is necessary to enable our understanding of the water balance components in the gauged watersheds. The distributed Soil Water Assessment Tool (SWAT) hydrologic model was applied to a research watershed, the Dry Creek Experimental Watershed (DCEW), near Boise Idaho to investigate its water balance components both temporally and spatially. Daily streamflow data from four streamflow gauges were used for calibration and validation of the model. Monthly estimates of streamflow during the calibration phase by SWAT produced satisfactory results with a Nash Sutcliffe coefficient of model efficiency 0.79. Since it is a continuous simulation model, as opposed to an event-based model, it demonstrated the limited ability in capturing both streamflow and soil moisture for selected rain-on-snow events during the validation period between 2005-07. Our implementation of SWAT showed that seasonal and annual water balance partitioning of precipitation into evapotranspiration, streamflow, soil moisture and drainage was not only possible but closely followed the trends of a typical semiarid watershed in the intermountain west. This study highlights the necessity for better techniques to precisely identify and drive the model with commonly observed climatic inversion-related snowmelt or rain-on-snow weather events. Estimation of key parameters pertaining to soil (e.g., available water content and saturated hydraulic conductivity), snow (e.g., lapse rates, melting) and vegetation (e.g., leaf area index and maximum canopy index) using additional field observations in the watershed is critical for better prediction

''Novel Optical Detection Schemes for In-Situ Mapping of Volatile Organochlorides in the Vadose Zone''

Long-term objective is to develop a system for measuring and identifying a wide range of volatile organic hydrocarbons, including aromatics, carbon tetrachloride, TCE and other organochlorides, at ppb levels in-situ in the subsurface (''at-depth'') using a fiber-optic REMPI probe in a cone penetrometer. Specific focus of much of the proposed work is to identify and optimize those experimental parameters which effect the in-situ determination of organic molecules in the subsurface using resonance-enhanced multi-photon ionization (REMPI). Emphasis is placed on visible excitation so that the high transmission of fiber-optics at visible wavelengths can be fully utilized. A fiber-optic REMPI system is being designed and integrated into an existing cone penetrometer system at LLNL. The design will be compatible with existing Raman and fluorescence probes

Evaluating Ground-Penetrating Radar use for water infiltration monitoring

International audienceGround-Penetrating Radar (GPR) was tested to monitor water infiltration in sand. Water was injected down an 81 cm long tubed hole, with a piezometer recording the depth of water and a tap valve used to adjust it to 15 cm ± 2 cm above the bottom of the tube. During the 20 minutes of infiltration a GPR system recorded a trace every second with its transmitter and receiver antennae at a fixed offset position on the surface. The signal, enhanced by differential correction, allows for tracing the evolution of top and bottom limits of the water bulb in space and time. Comparison with hydrodynamic model of the infiltration process and simulated radargrams prove that the GPR reflections trace the wetting front and the saturation bulb. A quantified estimation of the evolution of the top border of the wetting zone is provided

Sharp thermal transition in the forearc mantle wedge as a consequence of nonlinear mantle wedge flow

Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 38 (2011): L13308, doi:10.1029/2011GL047705.In the forearc mantle wedge, the thermal field depends strongly on slab-driven mantle wedge flow. The flow is in turn affected by the thermal field via the temperature dependence of mantle rheology. Using thermal modeling, we show that the nonlinear feedback between the thermal and flow fields always leads to complete stagnation of the mantle wedge over a shallow, weakened part of the slab-mantle interface and an abrupt onset of mantle flow further down-dip. The abrupt increase in flow velocity leads to a sharp thermal transition from a cold stagnant to a hot flowing part of the wedge. This sharp thermal transition is inherent to all subduction zones, explaining a commonly observed sharp arc-ward increase in seismic attenuation.This research was partially supported by National Science Foundation through a MARGINS postdoctoral fellowship (NSF OCE‐0840800) and by Natural Environment Research Council

Giant thermal expansion in 2D and 3D cellular materials

When temperature increases, the volume of an object changes. This property was quantified as the coefficient of thermal expansion only a few hundred years ago. Part of the reason is that the change of volume due to the variation of temperature is in general extremely small and imperceptible. Here, abnormal giant linear thermal expansions in different types of two‐ingredient microstructured hierarchical and self‐similar cellular materials are reported. The cellular materials can be 2D or 3D, and isotropic or anisotropic, with a positive or negative thermal expansion due to the convex or/and concave shape in their representative volume elements respectively. The magnitude of the thermal expansion coefficient can be several times larger than the highest value reported in the literature. This study suggests an innovative approach to develop temperature‐sensitive functional materials and devices

Upper mantle temperature and the onset of extension and break-up in Afar, Africa

It is debated to what extent mantle plumes play a role in continental rifting and eventual break-up. Afar lies at the northern end of the largest and most active present-day continental rift, where the East African Rift forms a triple junction with the Red Sea and Gulf of Aden rifts. It has a history of plume activity yet recent studies have reached conflicting conclusions on whether a plume still contributes to current Afar tectonics. A geochemical study concluded that Afar is a mature hot rift with 80 km thick lithosphere, while seismic data have been interpreted to reflect the structure of a young, oceanic rift basin above mantle of normal temperature. We develop a self-consistent forward model of mantle flow that incorporates melt generation and retention to test whether predictions of melt chemistry, melt volume and lithosphere–asthenosphere seismic structure can be reconciled with observations. The rare- earth element composition of mafic samples at the Erta Ale, Dabbahu and Asal magmatic segments can be used as both a thermometer and chronometer of the rifting process. Low seismic velocities require a lithosphere thinned to 50 km or less. A strong positive impedance contrast at 50 to 70 km below the rift seems linked to the melt zone, but is not reproduced by isotropic seismic velocity alone. Combined, the simplest interpretation is that mantle temperature below Afar is still elevated at 1450◦C, rifting started around 22–23 Ma, and the lithosphere has thinned from 100 to 50 km to allow significant decompressional melting