779 research outputs found

    Soil resource evaluation using precision farming techniques for selected sites in Tennessee

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    Crop yields have been shown to vary both between and within fields. Current technology allows for an accurate measurement of yield variability using Global Positioning System (GPS) and yield monitoring equipment. However, determination of the source of this variability is complicated by spatial differences in soil fertility, soil series, slope, and past management practices. This statewide study was designed to test the effectiveness of conventional soil survey maps against an intensive soil map created for various sites in Tennessee. Field Specific soil maps were developed using intensive soil sampling, incorporated with GPS and Geographic Information System (GIS) software. Relationships between soybean yield and soil mapping units were then statistically compared using spatial correlation models and S AS proc mixed procedures. Intensive soil maps better explained soybean yield variation (α = 0.05) although neither mapping technique was strongly related to yield. The site-specific maps were also better at distinguishing distinct yield groups by individual soil mapping unit. Specific properties of the soil and crop landscape were also investigated to determine their affect on soybean yield. Properties that had a significant affect on yield included subsoil texture, slope, and pH. Slope and subsoil texture interactions and drainage and effective rooting depth (ERD) interactions also showed yield differences. Soil properties that did not affect yield included soil drainage class, ERD, available phosphorous, and available potassium. Interactions of ERD and subsoil texture, ERD and slope, drainage and subsoil texture, and drainage and slope also showed no yield differences. Results of this study indicate that conventional mapping methods may not provide the necessary detail for use in today\u27s precision farming applications. When investigating specific properties within soil units, a limit is set in explaining yield variation by the soil unit boundary and further variability related to the soil unit cannot be explained. Although site specific maps are better than conventional mapping methods at predicting yields, an investigation into specific soil properties within a field may be necessary in providing a useful tool for producers implementing precision farming crop management

    On deadlock detection in distributed computing systems

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    With the advent of distributed computing systems, the problem of deadlock, which has been essentially solved for centralized computing systems, has reappeared. Existing centralized deadlock detection techniques are either too expensive or they do not work correctly in distributed computing systems. Although several algorithms have been developed specifically for distributed systems, the majority of them have also been shown to be inefficient or incorrect. A new algorithm is proposed which is more efficient than any existing distributed deadlock detection algorithm. (Author)supported in part by the Foundation Research Program of the Naval Postgraduate School with funds provided the by Chief of Naval Researchhttp://archive.org/details/ondeadlockdetect00badaApproved for public release; distribution is unlimited

    Linking urban design to sustainability : formal indicators of social urban sustainability field research in Perth, Western Australia

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    The making of a livable urban community is a complex endeavor. For much of the 20th Century plannersand engineers believed that modern and rational decision-making would create successful cities. Today, political leaders across the globe are considering ways to promote sustainable development and the concepts of New Urbanism are making their way from the drawing board to the ground. While much has changed in the world, the creation of a successful street is as much of an art today as it was in the 1960s.Our work seeks to investigate 'street life' in cities as a crucial factor towards community success. What arethe components of the neighborhood and street form that contributes to the richness of street life? To answer this question we rely on the literature. The aim of the Formal Indicators of Social Urban Sustainability studyis to measure the formal components of a neighborhood and street that theorists have stated important in promoting sustainability. This paper will describe how this concept helps to bridge urban design and sustainability. It will describe the tool and show how this was applied in a comparative assessment of Joondalup and Fremantle, two urban centers in the Perth metropolitan area

    Characterization of 1D photonic crystal nanobeam cavities using curved microfiber

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    We investigate high-Q, small mode volume photonic crystal nanobeam cavities using a curved, tapered optical microfiber loop. The strength of the coupling between the cavity and the microfiber loop is shown to depend on the contact position on the nanobeam, angle between the nanobeam and the microfiber, and polarization of the light in the fiber. The results are compared to a resonant scattering measurement

    Product Service System Innovation in the Smart City

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    Product service systems (PSS) may usefully form part of the mix of innovations necessary to move society toward more sustainable futures. However, despite such potential, PSS implementation is highly uneven and limited. Drawing on an alternate socio-technical perspective of innovation, this paper provides fresh insights, on among other things the role of context in PSS innovation, to address this issue. Case study research is presented focusing on a use orientated PSS in an urban environment: the Copenhagen city bike scheme. The paper shows that PSS innovation is a situated complex process, shaped by actors and knowledge from other locales. It argues that further research is needed to investigate how actors interests shape PSS innovation. It recommends that institutional spaces should be provided in governance landscapes associated with urban environments to enable legitimate PSS concepts to co-evolve in light of locally articulated sustainability principles and priorities

    Fast Readout of Split-Ring Resonators Made Simple and Low-Cost for Application in HPLC

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    Split-ring resonators (SRR) are simple electrical circuits that show a significant shift in resonance frequency even with the smallest changes in split capacitance, and thus in permittivity, electric conductivity, and dielectric losses of the split capacitor’s dielectric. Usually, the resonance frequency is derived from the frequency response, but recording the frequency spectrum takes a certain amount of time. Here, we present a new capillary split-ring resonator CaSRR with fast readout for liquid chromatography (LC), which is capable of accurately detecting very fast changes in split capacity. The proposed method is based on the detection of the transmitted signal at a single frequency that is analyzed by demodulation. The demodulated signal changes its amplitude depending on the shift of the resonance frequency. Our simple low-cost electronics enables an average sampling rate of 42 Hz with 128 averages of the demodulated signal and has a frequency stability of 840 mHz. Thus, a minimum change in permittivity of ∆εr,min = 11.26 × 10−3 can be detected. Finally, a chromatogram of one sugar (glucose) and one sugar alcohol (xylitol) is recorded using the SRR and is compared to a standard refractive index detector. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

    Multi-site Integrated Optical Addressing of Trapped Ions

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    One of the most effective ways to advance the performance of quantum computers and quantum sensors is to increase the number of qubits or quantum resources used by the system. A major technical challenge that must be solved to realize this goal for trapped-ion systems is scaling the delivery of optical signals to many individual ions. In this paper we demonstrate an approach employing waveguides and multi-mode interferometer splitters to optically address multiple 171Yb+^{171}\textrm{Yb}^+ ions in a surface trap by delivering all wavelengths required for full qubit control. Measurements of hyperfine spectroscopy and Rabi flopping were performed on the E2 clock transition, using integrated waveguides for delivering the light needed for Doppler cooling, state preparation, coherent operations, and detection. We describe the use of splitters to address multiple ions using a single optical input per wavelength and use them to demonstrate simultaneous Rabi flopping on two different transitions occurring at distinct trap sites. This work represents an important step towards the realization of scalable integrated photonics for atomic clocks and trapped-ion quantum information systems.Comment: 7 pages, 4 figures (+2 supplementary figures

    Effect of atomic layer deposition on the quality factor of silicon nanobeam cavities

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    In this work we study the effect of thin-film deposition on the quality factor (Q) of silicon nanobeam cavities. We observe an average increase in the Q of 38±31% in one sample and investigate the dependence of this increase on the initial nanobeam hole sizes. We note that this process can be used to modify cavities that have larger than optimal hole sizes following fabrication. Additionally, the technique allows the tuning of the cavity mode wavelength and the incorporation of new materials, without significantly degrading Q
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