A Low-cost Trajectory Estimation System for Drones and Rockets

Drone aircraft have become very popular during the last few years. These remote-controlled aircraft often rely on GPS receivers to track their position and velocity. However, it is often important for aircraft to measure other information that GPS cannot provide. Recent developments in single-board computers have facilitated the creation of cheap and effective embedded systems. This paper details the development and testing of a Raspberry Pi-based low-cost trajectory estimation system. Data acquired from a pitot probe, GPS receiver, altimeter, and accelerometer are fed into a Kalman filter to calculate a best-fit trajectory. The performance of the filter algorithm was evaluated using test case data. Further testing of the hardware and estimator performance will be performed during various future rocket test flights

Extinction Limits of Nonadiabatic, Catalyst-Assisted Flames in Stagnation-Point Flow

An idealized geometry corresponding to a premixed flame in stagnation-point flow is used to investigate the effects of catalysis on extending the extinction limits of on adiabatic stretched flames. Specifically, a surface catalytic reaction is assumed to occur on the stagnation plane, thereby augmenting combustion in the bulk gas with a exothermic surface reaction characterized by a reduced activation energy. Assuming the activation energies remain large, an asymptotic analysis of the resulting flame structure yields a formula for the extinction limit as a function of various parameters. In particular, it is demonstrated that the presence of a surface catalyst can extend the burning regime, thus counterbalancing the effects of heat loss and flame stretch that tend to shrink it. The analysis is relevant to small-volume combustors, where the increased surface-to-volume ratio can lead to extinction of the nonadiabatic flame in the absence of a catalyst

Surface Characterization of Red Maple Strands After Hot Water Extraction

The conversion of carbohydrates from wood to make biofuels such as ethanol is a topic of widespread interest. A promising approach is the removal of the hemicellulosic wood component by extraction with subsequent conversion to biofuels while continuing to produce forest products. The impact of extraction on wood strands for use in strand-based composites was investigated. One tree of red maple (Acer rubrum L.) was used to create strands 10.2 cm long with a thickness of 0.9 mm. Three hot water extraction procedures at 160°C, corresponding to severity factors (SF) of 2.71, 3.54, and 3.81, were used resulting in an average weight loss of 5.7, 16.9 and 18.1%, respectively. Scanning electron microscopic imaging of selected wood strands showed that pores in the cell wall increased as SF increased. The distribution and size of the cell-wall pore structure showed up to a 22.2% increase. The sessile drop method, using distilled water, diiodomethane, and ethylene glycol, indicated more pronounced liquid wetting and penetration as SF increased. Inverse gas chromatography led to the finding that dispersive surface-free energy and acid-base characteristics increase with SF. The extraction procedures should be kept below a SF of 3.54 to minimize changes in adhesion performance

Acquisition of Advanced Engineered Wood Composites Manufacturing and Science Laboratory

This action is in response to the Major Research Instrumentation Initiative MRI\u2798 (NSF-98-16). The purpose is to upgrade a Composite-Reinforced-Wood (CRW) Manufacturing Science Laboratory at the University of Maine. The laboratory is part of a new facility designed to develop the next generation of wood composites for construction. Recent research has shown that Composite Reinforced Wood (CRW) offers superior properties at reduced costs. As in the development of reinforced and prestressed concrete, basic research is needed to unlock the full potential of a wide variety of CRW structural members, e.g. joists, beams, columns, panel and connections. CRW hybrids are unique in that two very different classes of material, FRP and wood are used together; thus the principles governing the short and long-term structural behavior differ in many ways form those involving only one of the two materials. This project will focus on:Developing a new class of FRP reinforcing materials that are compatible with wood, particularly its hypoexpansion and visco-elastic properties.Developing and maintaining over time the interface (bond) between the two materials needed to ensure full composite action (this will require a basic understanding of the mechanisms of bond durability).Developing a basic understanding of the short and long-term behavior of CRW structural elements including performance over the full range of loading, ultimate strength, ductility, creep, fatigue, and moisture/temperature/UV cycling.The research is conducted at four different levels: micro, meso, macro and structural. A multi-disciplinary team will conduct the research composing ten engineers and scientists from three units at the University of Maine (civil/structural engineering, wood science and technology, and chemical engineering), the industry-supported SPI composites Institute, the Composites Materials Engineering Center (COMTEC) in Winona MN, and the USDA Forest Products laboratory in Madison

Fast spin exchange between two distant quantum dots

The Heisenberg exchange interaction between neighboring quantum dots allows precise voltage control over spin dynamics, due to the ability to precisely control the overlap of orbital wavefunctions by gate electrodes. This allows the study of fundamental electronic phenomena and finds applications in quantum information processing. Although spin-based quantum circuits based on short-range exchange interactions are possible, the development of scalable, longer-range coupling schemes constitutes a critical challenge within the spin-qubit community. Approaches based on capacitative coupling and cavity-mediated interactions effectively couple spin qubits to the charge degree of freedom, making them susceptible to electrically-induced decoherence. The alternative is to extend the range of the Heisenberg exchange interaction by means of a quantum mediator. Here, we show that a multielectron quantum dot with 50-100 electrons serves as an excellent mediator, preserving speed and coherence of the resulting spin-spin coupling while providing several functionalities that are of practical importance. These include speed (mediated two-qubit rates up to several gigahertz), distance (of order of a micrometer), voltage control, possibility of sweet spot operation (reducing susceptibility to charge noise), and reversal of the interaction sign (useful for dynamical decoupling from noise).Comment: 6 pages including 4 figures, plus 8 supplementary pages including 5 supplementary figure

TAMMiCol: Tool for analysis of the morphology of microbial colonies.

Many microbes are studied by examining colony morphology via two-dimensional top-down images. The quantification of such images typically requires each pixel to be labelled as belonging to either the colony or background, producing a binary image. While this may be achieved manually for a single colony, this process is infeasible for large datasets containing thousands of images. The software Tool for Analysis of the Morphology of Microbial Colonies (TAMMiCol) has been developed to efficiently and automatically convert colony images to binary. TAMMiCol exploits the structure of the images to choose a thresholding tolerance and produce a binary image of the colony. The images produced are shown to compare favourably with images processed manually, while TAMMiCol is shown to outperform standard segmentation methods. Multiple images may be imported together for batch processing, while the binary data may be exported as a CSV or MATLAB MAT file for quantification, or analysed using statistics built into the software. Using the in-built statistics, it is found that images produced by TAMMiCol yield values close to those computed from binary images processed manually. Analysis of a new large dataset using TAMMiCol shows that colonies of Saccharomyces cerevisiae reach a maximum level of filamentous growth once the concentration of ammonium sulfate is reduced to 200 μM. TAMMiCol is accessed through a graphical user interface, making it easy to use for those without specialist knowledge of image processing, statistical methods or coding

Evaluation of Load Transfer in the Cellulosic-Fiber/Polymer Interphase Using a Micro-Raman Tensile Test

The objectives of this research were (1) to use a Raman micro-spectroscopic technique to determine the tensile stress distributions of a cellulosic-fiber/polymer droplet interphase, and (2) to examine if the stress profile could be used to evaluate load transfer in fiber/polymer adhesion. Cellulosic fibers were treated with various silanes (amino, phenylamino, phenyl, and octadecyl functionalities) and a styrene-maleic anhydride copolymer to create different interphases upon bonding with polystyrene. A single fiber, bonded with a micro-droplet of polystyrene in the mid-span region of its gage length, was strained in tension. Raman spectra were collected at five-micrometer intervals along the embedded region of the fiber. The stress-dependent peak of cellulose (895 cm-1) was analyzed for frequency shift so that the local tensile stress in the interface region could be determined. Results showed that the local tensile stresses of the strained fiber were lower in the embedded region compared to the exposed region, suggesting a transfer of load from the fiber to the matrix polymer. A deeper and sharper decline of the stress profile was observed when the fiber/droplet interaction was enhanced. Further analyses, involving conversion of tensile stress profiles to shear stress distributions in the interphase, confirmed that the micro-Raman/tensile test can be employed to evaluate fiber/matrix interfacial bonding in composites. This success signifies the possibility of evaluating adhesion between cellulosic fibers and brittle polymers, which is difficult to study using common micromechanical tests. Use of the micro-Raman technique can improve our understanding of wood/polymer adhesion

An inverted-sandwich diuranium μ-η5:η5-cyclo-P5 complex supported by U-P5 δ-bonding

Reaction of [U(TrenTIPS)] [1, TrenTIPS=N(CH2CH2NSiiPr3)3] with 0.25 equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo-P5 complex [{U(TrenTIPS)}2(μ-η5:η5-cyclo-P5)] (2). All prior examples of cyclo-P5 are stabilized by d-block metals, so 2 shows that cyclo-P5 does not require d-block ions to be prepared. Although cyclo-P5 is isolobal to cyclopentadienyl, which usually bonds to metals via σ- and π-interactions with minimal δ-bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized δ-bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo-P5 unit to give a cyclo-P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo-P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium δ-symmetry 5f orbitals

Role of habit in treatment adherence among adults with cystic fibrosis

Among adults with cystic fibrosis (CF), medication adherence is low and reasons for low adherence are poorly understood. Our previous exploratory study showed that stronger 'habit' (ie, automatically experiencing an urge to use a nebuliser) was associated with higher nebuliser adherence. We performed a secondary analysis of pilot trial data (n=61) to replicate the earlier study and determine whether habit-adherence association exists in other cohorts of adults with CF. In this study, high adherers also reported stronger habit compared with low adherers. Habit may be a promising target for self-management interventions. ACtiF pilot, ISRCTN13076797. [Abstract copyright: © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.