A military perspective on small unmanned aerial vehicles

In recent years, advancements in three technology areas, microelectronics, MEMS sensors, and GPS receivers, have allowed small UAVs to overcome critical deficiencies and become practical for insertion into the military mainstream. The maturation and commercialization of these technologies have resulted in readily available components that have decreased in both size and cost, to the point where truly low-cost, highly capable, small UAVs are possible. In particular, inertial devices such as MEMS accelerometers and angular rate sensors, pressure sensors, and magnetometers have reached the point where they are reliable, accurate, and affordable. These devices allow the determination of vehicle state with the precision required to enable autonomous flight. In addition, advanced microelectronic devices, such as digital signal processors, field programmable gate arrays, and microcontrollers have enabled sophisticated flight control functions, including fully autonomous flight using GPS waypoints. In combination, these advances have allowed small UAVs such as Pointer, Raven, and Dragon Eye to move into full-scale production and continue to allow the progression of UAVs into smaller and smaller packages. To address several of the deployment issues connected with small UAVs, a gun-launched version, along with the underpinning technologies, is under development. This device represents a clear departure from conventional UAVs with several clear advantages; however, it also contains severe design challenges, as well as test and evaluation dilemmas. An option of this type is envisioned not as a replacement for conventional small UAVs but rather as an augmenting capability.     

A Low-Power Wide-Dynamic-Range Analog VLSI Cochlea

Low-power wide-dynamic-range systems are extremely hard to build. The biological cochlea is one of the most awesome examples of such a system: It can sense sounds over 12 orders of magnitude in intensity, with an estimated power dissipation of only a few tens of microwatts. In this paper, we describe an analog electronic cochlea that processes sounds over 6 orders of magnitude in intensity, and that dissipates 0.5 mW. This 117-stage, 100 Hz to 10 KHz cochlea has the widest dynamic range of any artificial cochlea built to date. The wide dynamic range is attained through the use of a wide-linear-range transconductance amplifier, of a low-noise filter topology, of dynamic gain control (AGC) at each cochlear stage, and of an architecture that we refer to as overlapping cochlear cascades. The operation of the cochlea is made robust through the use of automatic offset-compensation circuitry. A BiCMOS circuit approach helps us to attain nearly scale-invariant behavior and good matching at all frequencies. The synthesis and analysis of our artificial cochlea yields insight into why the human cochlea uses an active traveling-wave mechanism to sense sounds, instead of using bandpass filters. The low power, wide dynamic range, and biological realism make our cochlea well suited as a front end for cochlear implants.     

In vivo analysis of murine serum sulfate metabolism and splenic glycosaminoglycan biosynthesis during acute inflammation and amyloidosis

OBJECTIVE: Highly sulfated glycosaminoglycans (GAG) have been demonstrated in every form of amyloid examined to date. Based on temporal studies in murine amyloidogenesis heparan sulfate is deposited coincidentally with the amyloid protein. Our purpose was to follow in vivo GAG synthesis by monitoring 35SO4 incorporation during amyloidogenesis. Several necessary previously unexamined nonamyloidogenic controls were also examined. METHODS: Murine splenic amyloid was induced with lipopolysaccharide (LPS) and amyloid enhancing factor (AEF). Splenic GAG synthesis was monitored by 35SO4 incorporation. Corrections were made for alterations in SO4 metabolism which occur during inflammation. RESULTS: All animals with an inflammatory reaction had a marked increase in GAG synthesis. Those animals receiving AEF, or AEF+LPS, had a significant increase in heparan sulfate synthesis. This was particularly profound in the group developing amyloid (i.e., AEF+LPS). CONCLUSION: Our results indicate that critical factors in amyloid deposition include quantitative as well as qualitative changes that take place in tissue GAG synthesis. A distinct metabolic effect of AEF is demonstrated for the first time.     

Critical issues in the instruction of the learning disabled.

This article addresses several issues and trends relevant to the instruction of the learning disabled (LD). Although the concept of LD has received some support as a diagnostic category, limited data exist that demonstrate the effect of different instructional methods on the academic deficits of LD students. In this review, attempts to remediate LD are examined according to the adequacy of the theoretical context that guides the instruction and the efficacy and validity of the remediation procedures. Selected studies representative of medical, psychoeducational, neuropsychological, behavioral, linguistic, and cognitive treatment approaches are reviewed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kinetic analysis of plasma VLDL-TG and VLDL-remnant-TG turnover in anesthetized rats

We have estimated the turnover and relative pool sizes of nascent-VLDL-TG and VLDL-remnants-TG in anesthetized rats. [1-¹⁴C]Palmitoyl- and [2-³H]glyceryl-labeled “VLDL”-TG (including nascent VLDL-TG and VLDL-remnants-TG) were prepared by injecting labeled palmitate and glycerol into donor rats. Labeled serum from these rats was then injected intravenously into nembutalized male rats and serial blood samples taken for 30 min. Special care was taken to define any early components in the labeled “VLDL”-TG disappearance curves. In other experiments, the donors were rendered functionally hepatectomized 30 min after injection of³H-glycerol and the endogenous labeled VLDL-TG was allowed to circulate 30–60 min before collection of the TG-labeled VLDL-remnants-containing serum. The latter was injected into 4 recipient nembutalized rats and the remnant-TG-turnover measured by serial sampling as above. In two cases,¹⁴C-“VLDL” and³H-VLDL-remnants were injected as a single bolus into ether-anesthetized rats. Despite its complex composition, “VLDL”-TG in most cases disappeared in a single exponential fashion for 30 min with an average half-life of 5.9 min in nembutalized and 2.8 in ether-anesthetized rats. VLDL-remnants-TG showed a more complex behavior, but contained a major rapid component with a mean t_1/2 of ca. 1.5 min in both groups. The data, analyzed by multicompartmental analysis, were fitted to a simple model in which turnover of a larger nascent VLDL-TG pool with formation of a more rapidly turning over smaller pool of VLDL-remnant-TG is the rate-limiting step in overall TG removal from the d<1.006 fraction of rat serum. The data are consistent with our theoretical prediction that under these conditions the kinetics of the VLDL-remnants cannot be resolved from analysis of the total composite “VLDL” (nascent plus remnant) pool.     

Oxide formation during etching of gallium arsenide

Characterisation of n-type GaAs, etched in a 5:1:1 mixture of H₂SO₄:H₂O₂:H₂O, was performed using X-ray photoelectron spectroscopy (XPS) and electrochemical AC impedance. Quantitative XPS analysis of GaAs indicated that the as-received wafers had a gallium-rich native oxide which was not affected by solvent degreasing treatments. Subsequent, oxidative etching formed a thinner arsenic-rich oxide. It is suggested that etching causes initial thinning of the native oxide; subsequently, transport of Ga and As ions occurs through the film by high-field ionic conduction. Arsenic enrichment in the resultant oxide film arises from the greater mobility of Ga³⁺ ions compared with As³⁺ ions as well as the relative solubility of Ga₂O₃ compared with As₂O₃. The as-received oxide film thickness, determined from the ratio of the oxide to substrate XPS peaks, was approximately 1.1 nm. After etching this was reduced to about 0.7 nm. This thickness is consistent with the driving voltage for oxide formation being provided by the electrochemical potential difference between hydrogen peroxide and the GaAs wafer (i.e. between 0.4 V, for As, and 1.2 V, for Ga, at a nm V⁻¹ ratio of 2). Capacitance measurements, derived from electrochemical impedance data, combined with film thickness data, gave a value of about 5 for the dielectric constant of As₂O₃.     

Interlocking, Ribbing and Folding: Explorations in Parametric Constructions

This paper presents three projects involving the design and fabrication of architectural structures through the use of different parametric software and digital manufacturing methods. The first project is a flexible partition composed of interlocking elements shaped using a laser-cutter. The second project is a university exhibition unit made with various wooden panels manufactured through a computer numerical controlled (CNC) system. The third project is a system of metal sheets folded by digital machines to create urban circulation spaces. The three works develop a parametric programming of geometry based on certain technical factors, enabling the recognition of patterns of interaction between formal and constructive issues involved in the definition of shapes through parametric controls. Differences in materials and processes are contrasted by similarities of function and conditions involved, creating a system of local, global, productive and environmental parameters that produces a repertoire of self-similar dimensions and variations as well as multiple possibilities of initial setups and final configurations. It suggests a specific field of design exploration focusing on the development of differentiated components and variable architectural configurations, in a kind of open parametric system.     

Inhibition of corrosion by a mixture of nonchromate pigments in organic coatings on galvanized steel

We consider several possible substitutes for toxic chromate pigments. Among the most promising compositions for the corrosion inhibition of galvanized steel with a protective organic coating, we should mention a mixture of phosphate- and calcium-containing pigments. As was shown earlier, such a mixture possesses a high efficiency under conditions of the corrosion of zinc and galvanized steel sheet; however, it is less efficient for the protection of carbon steels. This pigment mixture forms an adsorbed phosphate film on the metal and hinders the course of anodic and cathodic reactions. Zinc ions play an important role for obtaining a synergistic protective effect, increasing the coherence and decreasing the porosity of the deposited film. Traditional and local electrochemical methods (EIS and SVE) were used for studying the corrosion of galvanized steel with coatings in acid rain solution. The data obtained corroborated the high anticorrosive efficiency of a pigment mixture in an organic coating on galvanized steel. In addition, we established some specific features of its inhibiting action near defects in the coating.Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 3, pp. 74–80, May–June, 2004.     

Material properties and fire test results

Five material properties commonly used to describe the fire behavior of solids were evaluated as sole explanatory variables for four small‐scale fire tests with pass/fail outcomes by using a physically based probabilistic (phlogistic) burning model. The phlogistic model describes the likelihood of passing vertical Bunsen burner tests and a regulatory heat release rate test reasonably well over a wide range of material properties, as deduced from the correlation coefficient and mean deviation of the predicted and measured values. Of the thermal, combustion, and fire properties examined, the best predictors of the likelihood of passing the fire tests of this study were the heat of combustion of the sample, the heat release capacity, and the heat release parameter. The relative merits and drawbacks of qualitative (threshold) and quantitative (probabilistic) approaches to predicting fire test results using thermal and combustion properties are discussed. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.