2,191 research outputs found
Taking Shots at Private Military Firms: International Law Misses its Mark (Again)
Part I of this Article takes a brief tour through military history on the consistent use of mercenaries through the ages, which Peter Singer illuminates masterfully in Corporate Warriors. Next, a brief overview on the binding nature (or not) of international custom and treaty is explored in Part II and then the codifications of international law are taken up in Part III, beginning with the Hague and Geneva Conventions. Several United Nations (“U.N.”) instruments are analyzed for their efficacy in changing the long-standing customary international law on the use of mercenaries and whether or not each is applicable to PMF contractors. Part IV closes out the Article by discussing alternative bodies of domestic law that provide criminal accountability, including the recent case of Alaa Mohammad Ali, a civilian contractor working in Iraq who was convicted on June 23, 2008 by court martial under the recent changes to the Uniform Code of Military Justice (“UCMJ”)
Thoriated nickel bonded by solid-state diffusion method
Solid-state diffusion bonding in an inert-gas atmosphere forms high-strength joints between butting or overlapping surfaces of thoriated nickel. This method eliminates inert-phase agglomeration
Exposure of Tradescantia Microspores to Periodic Vibrations of 40-100 Hertz
Spherical chromosomal fragments determined in exposure of Tradescantia microspores to periodic vibration
Evaluation of Superplastic Forming and Weld-brazing for Fabrication of Titanium Compression Panels
The two titanium processing procedures, superplastic forming and weld brazing, are successfully combined to fabricate titanium skin stiffened structural panels. Stiffeners with complex shapes are superplastically formed using simple tooling. These stiffeners are formed to the desired configuration and required no additional sizing or shaping following removal from the mold. The weld brazing process by which the stiffeners are attached to the skins utilize spot welds to maintain alignment and no additional tooling is required for brazing. The superplastic formed/weld brazed panels having complex shaped stiffeners develop up to 60 percent higher buckling strengths than panels with conventional shaped stiffeners. The superplastic forming/weld brazing process is successfully scaled up to fabricate full size panels having multiple stiffeners. The superplastic forming/weld brazing process is also successfully refined to show its potential for fabricating multiple stiffener compression panels employing unique stiffener configurations for improved structural efficiency
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A method for supervision of rural schools in hill towns of Massachusetts
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Evapotranspiration Mapping for Forest Management in California's Sierra Nevada
We assessed the response of densely forested watersheds with little apparent annual water limitation to forest disturbance
and climate variability, by studying how past wildfires changed forest evapotranspiration, and what past evapotranspiration
patterns imply for the availability of subsurface water storage for drought resistance. We determined annual spatial patterns
of evapotranspiration using a top-down statistical model, correlating measured annual evapotranspiration from eddycovariance
towers across California with NDVI (Normalized Difference Vegetation Index) measured by satellite, and with
annual precipitation. The study area was the Yuba and American River watersheds, two densely forested watersheds in the
northern Sierra Nevada. Wildfires in the 1985-2015 period resulted in significant post-fire reductions in evapotranspiration
for at least 5 years, and in some cases for more than 20 years. The levels of biomass removed in medium-intensity fires (25-
75% basal area loss), similar to magnitudes expected from forest treatments for fuels reduction and forest health, reduced
evapotranspiration by as much 150-200 mm yr-1 for the first 5 years. Rates of recovery in post-wildfire evapotranspiration
confirm the need for follow-up forest treatments at intervals of 5-20 years to sustain lower evapotranspiration, depending
on local landscape attributes and interannual climate. Using the metric of cumulative precipitation minus evapotranspiration
(P-ET) during multi-year dry periods, we found that forests in the study area showed little evidence of moisture stress
during the 1985-2018 period of our analysis, owing to relatively small reliance on interannual subsurface water storage to
meet dry-year evapotranspiration needs of vegetation. However, more-severe or sustained drought periods will push some
lower-elevation forests in the area studied toward the cumulative P-ET thresholds previously associated with widespread
forest mortality in the southern Sierra Nevada
Surface chemical and physical behavior of chrysotile asbestos in natural waters and water treatment
Chrysotile asbestos fibers enter California waters from physical weathering of magnesium-silicate, serpentine rocks in mountains of the northern and central portions of the state. Chrysotile particles, initially positively charged below pH 8.9 because of their magnesium-hydroxide surface, become negatively charged due to dissolution and adsorption of organic matter.
Chrysotile suspended in 0.1 M inorganic electrolyte at pH 7-10 for up to five days dissolves with magnesium being released in excess of the 3:2 Mg:Si to silica molar ratio in the solid. The rate of magnesium release exhibits a fractional dependence on hydrogen-ion concentration:
r = k_1'[H^+]^(0.24)
The observed rate constant, k_l', depends on dissolution mechanism, specific surface area of the solid and charge-potential relation at the surface. Interpreted in terms of a site-binding model for adsorption and desorption of protons on the surface, the fractional dependence implies that dissolution is limited by a chemical reaction involving an average of less than one adsorbed proton per magnesium ion released into solution. Silica release from chrysotile shows no clear pH dependence.
The rate of magnesium release is independent of the anions NO^(3-), Cl^- , SO_4^(2-), HCO_3^-, oxalate or catechol. Oxalate inhibited and catechol slightly enhanced silica release over the pH range 7.5-8.5; other anions had no systematic effect. Chrysotile's dissolution rate (10^(-15.7) mol/cm^2·s at pH 8) is consistent with observations on other magnesium silicates and brucite.
Catechol adsorption onto chrysotile or aluminum oxide (pH 7.5-8.5) does not reach equilibrium but increases over five days. After one day the maximum adsorption density (Langmuir adsorption equation) on chrysotile is 0.7 x 10^(-9) mol/cm^2 (50 x 10^(-6) mg C/cm^2), approximately one-third of the estimated number of surface sites available for proton exchange. The maximum adsorption density for natural organic matter was near 30 x 10^(-6) mg C/cm^2 on both chrysotile and aluminum oxide.
Chrysotile adsorbs sufficient catechol, oxalate, phthalate or natural organic matter within one day to reverse its surface charge. The extent of reversal is larger than observed for adsorption of the same organics on aluminum oxide, because of selective dissolution of chrysoti1e's outer magnesium-hydroxide layer.
In reservoirs, submicron-sized chrysoti1e particles coagulate with larger (>2 μm), negatively-charged particles that subsequently settle out. The rate at which freshly-suspended, positively-charged chrysotile fibers coagulate is at least ten-fold greater than the rate for aged, negatively-charged fibers coagulate.
Removal of chrysotile particles in water treatment occurs by deposition of fibers onto sand grains in filtration. Capture efficiency for single fibers is low; removal is enhanced 10-fold or more by incorporating fibers into larger flocs. Removal of chrysotile fibers in water filtration to levels near detection limits (typically 10^5-10^6 fibers/L) is possible; consistent achievement of this level will require a higher removal efficiency than is routinely achieved in treatment plants receiving water from the California aqueduct
Analysis and test of superplastically formed titanium hat-stiffened panels under compression
Four hat-stiffened titanium panels with two different stiffener configurations were fabricated by superplastic forming/weld brazing and tested under a moderately heavy compressive load. The panels had the same overall dimensions but differed in the shape of the hat-stiffener webs; three panels had stiffeners with flat webs and the other panel had stiffeners with beaded webs. Analysis indicated that the local buckling strain of the flat stiffener web was considerably lower than the general panel buckling strain or cap buckling strain. The analysis also showed that beading the webs of the hat stiffeners removed them as the critical element for local buckling and improved the buckling strain of the panels. The analytical extensional stiffness and failure loads compared very well with experimental results
Curved cap corrugated sheet
The report describes a structure for a strong, lightweight corrugated sheet. The sheet is planar or curved and includes a plurality of corrugation segments, each segment being comprised of a generally U-shaped corrugation with a part-cylindrical crown and cap strip, and straight side walls and with secondary corrugations oriented at right angles to said side walls. The cap strip is bonded to the crown and the longitudinal edge of said cap strip extends beyond edge at the intersection between said crown and said side walls. The high strength relative to weight of the structure makes it desirable for use in aircraft or spacecraft
Glass bead shot peening retards stress corrosion failure of titanium tanks
Rigidly controlled shot peening retards the incompatibility between titanium alloys and nitrogen tetroxide in rocket-propellant storage tanks. This sets up a residual compressive stress in the surface of a material which reduces tensile stresses in the material fibers, alleviating stress corrosion
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