566 research outputs found

    Development of a photosynthesis model with an emphasis on ecological applications

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    A physiologically based steady-state model of whole leaf photosynthesis (WHOLEPHOT) is detailed which describes the functional dependence of net photosynthesis in C 3 leaves on [CO 2 ], [O 2 ], incident radiant flux (PhAR), and leaf temperature. The model simulates among other phenomena a) observed [CO 2 ], [O 2 ], and temperature effects on the initial slope of light response curves, b) a C 3 type temperature response curve of net photosynthesis, c) a shift of the optimum temperature of net photosynthesis to higher temperatures with increasing light intensity, and d) observed temperature and [O 2 ] effects on the CO 2 compensation point. Model parameters are derived from published response data of several C 3 species. Simulations also demonstrate that parameter changes based on literature data result in acclimation-like changes in net photosynthesis response with respect to light intensity and temperature. The advantages of this model are that the number of parameters is minimized in order to focus on environmental effects and that all parameters can be determined from measured net photosynthesis responses.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47727/1/442_2004_Article_BF00344999.pd

    Directly Printable Organic ASK Based Chipless RFID Tag for IoT Applications

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    A chipless RFID tag with unique ASK encoding technique is presented in this paper. The coding efficiency is enhanced regarding tag capacity. The amplitude variations of the backscattered RFID signal is used for encoding data instead of OOK Strips of different widths are used to have amplitude variations. The ASK technique is applied using three different substrates of Kapton (R) HN, PET, and paper. To incorporate ASK technique, dual polarized rhombic shaped resonators are designed. These tags operate in the frequency range of 3.1-10.6 GHz with size of 70 x 42 mm(2). The presented tags are flexible and offer easy printability. The paper-based decomposable organic tag appears as an ultra low-cost solution for wide scale tracking. This feature enables them to secure a prominent position in the emerging fields of IoT and green electronics

    Night vision obstacle detection and avoidance based on Bio-Inspired Vision Sensors

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    Moving towards autonomy, unmanned vehicles rely heavily on state-of-the-art collision avoidance systems (CAS). However, the detection of obstacles especially during night-time is still a challenging task since the lighting conditions are not sufficient for traditional cameras to function properly. Therefore, we exploit the powerful attributes of event-based cameras to perform obstacle detection in low lighting conditions. Event cameras trigger events asynchronously at high output temporal rate with high dynamic range of up to 120 dBdB. The algorithm filters background activity noise and extracts objects using robust Hough transform technique. The depth of each detected object is computed by triangulating 2D features extracted utilising LC-Harris. Finally, asynchronous adaptive collision avoidance (AACA) algorithm is applied for effective avoidance. Qualitative evaluation is compared using event-camera and traditional camera.Comment: Accepted to IEEE SENSORS 202

    Using the SWAT model to improve process descriptions and define hydrologic partitioning in South Korea

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    Watershed-scale modeling can be a valuable tool to aid in quantification of water quality and yield; however, several challenges remain. In many watersheds, it is difficult to adequately quantify hydrologic partitioning. Data scarcity is prevalent, accuracy of spatially distributed meteorology is difficult to quantify, forest encroachment and land use issues are common, and surface water and groundwater abstractions substantially modify watershed-based processes. Our objective is to assess the capability of the Soil and Water Assessment Tool (SWAT) model to capture event-based and long-term monsoonal rainfall–runoff processes in complex mountainous terrain. To accomplish this, we developed a unique quality-control, gap-filling algorithm for interpolation of high-frequency meteorological data. We used a novel multi-location, multi-optimization calibration technique to improve estimations of catchment-wide hydrologic partitioning. The interdisciplinary model was calibrated to a unique combination of statistical, hydrologic, and plant growth metrics. Our results indicate scale-dependent sensitivity of hydrologic partitioning and substantial influence of engineered features. The addition of hydrologic and plant growth objective functions identified the importance of culverts in catchment-wide flow distribution. While this study shows the challenges of applying the SWAT model to complex terrain and extreme environments; by incorporating anthropogenic features into modeling scenarios, we can enhance our understanding of the hydroecological impact

    The diurnal time course of net photosynthesis of soybean leaves: Analysis with a physiologically based steady-state photosynthesis model

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    A physiologically based steady-state model of whole leaf photosynthesis (WHOLEPHOT) is used to analyze observed net photosynthesis daily time courses of soybean, Glycine max (L.) Merr., leaves. Observations during two time periods of the 1978 growing season are analyzed and compared. After adjustment of the model for soybean, net photosynthesis rates are calculated with the model in response to measured incident light intensity, leaf temperature, air carbon dioxide concentration, and leaf diffusion resistance. The steady-state calculations closely approximate observed net photosynthesis. Results of the comparison reveal a decrease in photosynthetic capacity in leaves sampled during the second time period, which is associated with decreasing ability of leaves to respond to light intensity and internal air space carbon dioxide concentration, increasing mesophyll resistance, and increasing stomatal resistance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47732/1/442_2004_Article_BF00346258.pd

    Directly Printable Frequency Signature Chipless RFID Tag for IoT Applications

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    This Paper proposes a low-cost, compact, flexible passive chipless RFID tag that has been designed and analyzed. The tag is a bowtie-shaped resonator based structure with 36 slots; where each patch is loaded with 18 slots. The tag is set in a way that each slot in a patch corresponds to a metal gap in the other patch. Hence there is no mutual interference, and high data capacity of 36 bits is achieved in such compact size. Each slot corresponds to a resonance frequency in the RCS curve, and each resonance corresponds to a bit. The tag has been realized for Taconic TLX-0, PET, and Kapton®HN (DuPontTM) substrates with copper, aluminum, and silver nanoparticle-based ink (Cabot CCI-300) as conducting materials. The tag exhibits flexibility and well optimized while remaining in a compact size. The proposed tag yields 36 bits in a tag dimension of 24.5 x 25.5 mm^2. These 36 bits can tag 2^36 number of objects/items. The ultimate high capacity, compact size, flexible passive chipless RFID tag can be arrayed in various industrial and IoT-based applications

    A Compact Flexible and Frequency Reconfigurable Antenna for Quintuple Applications

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    A novel, compact coplanar waveguide fed flexible antenna is presented. The proposed design uses flexible Rogers RT/duroid 5880 (0.508mm thickness) as a substrate with small size of 30×28.4 mm^2. Two switches are integrated on the antenna surface to change the current distribution which consequently changes the resonance frequency under different conditions of switches, thereby making it a frequency reconfigurable antenna. The antenna design is simulated on CST®MWS®. The proposed antenna exhibits VSWR<2 and appreciable radiation patterns with positive gain over desired frequency bands. Good agreement exists between simulated and measured results. On the basis of results, the proposed antenna is envisioned to be deployed for the following applications; aeronautical radio navigation [4.3 GHz, AMT fixed services [4.5 GHz, WLAN [5.2 GHz, Unlicensed WiMAX [5.8 GHz and X-band [7.5 GHz
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