Applicability of time-of-flight-based ground and multispectral aerial imaging for grapevine canopy vigour monitoring under direct root-zone deficit irrigation

ABSTRACT

This study investigates the applicability of ground-based 3D time-of-flight (ToF) imaging and small unmanned aerial system (UAS) integrated multispectral imaging as a rapid grapevine canopy vigour mapping tool for decision support during crop production management. Direct root-zone deficit irrigation was applied to grapevines with continuous and pulse irrigation techniques at 15%, 30%, and 60% rates as that of standard irrigation rate (100%) established by the grower in a commercial production. The control block was irrigated continuously at 100% standard irrigation rate. Field plots were imaged using ground platform integrated with 3D ToF imaging sensor and small UAS-integrated multispectral camera at 128 and 65 days before the harvest to estimate the canopy vigour variability associated with irrigation treatments. Customized as well as standard methods (convex hull and voxel grid) were utilized to extract canopy attributes (e.g. volume) from the 3D ToF imaging sensor data. The multispectral images were processed to extract normalized and green normalized difference vegetation index images. Resulting data were used to estimate canopy area ratio i.e. the ratio between the grapevine canopy area with respect to the total area in selected region of interest. A significant correlation (r = 0.34) between canopy volume estimated by customized algorithm and aerial canopy area ratio was observed. Custom canopy volume estimates were also highly correlated (r = 0.79) with voxel grid derived canopy volume data. Overall, 60% continuous direct root zone deficit irrigation appeared to produce canopy volume/vigour comparable with those under control treatment. Results also suggest that grower can utilize either or both (ground and aerial) grapevine canopy mapping techniques for effective management.     

Practices,projects and portfolios: Current research trends and new directions

Project portfolio management (PPM) bridges strategy and project management. Traditional research in PPM has primarily investigated the rational, top-down and structural aspects of strategizing. By doing so, it has failed to focus on the underlying practices that are triggered by the strategy and how these practices frame strategy implementation. Practice-based research provides a methodological lens to explore the reality of strategic enactment through the project portfolio. Practice-based perspectives are under-represented in PPM research; therefore the aim of this paper is to provide an agenda for further practice-based research in PPM. Central to this agenda is a concern with various aspects of practice, including its discursivity, representation, dynamic capabilities, leadership and materiality.     

Fabrication of highly sensitive MnO2/F-MWCNT/Ta hybrid nanocomposite sensor with different MnO2 overlayer thickness for H2O2 detection

In this work, we report the development of MnO₂/F-MWCNT/Ta hybrid nanocomposite sensor with different MnO₂ overlayer thickness for the detection of H₂O₂ in real samples. A novel two-step process using e-beam evaporation and spray pyrolysis deposition was adopted for the synthesis of hybrid MnO₂/F-MWCNT/Ta electrodes. SE morphology revealed smaller-sized, compact grains of MnO₂ infiltrated on the outermost walls of MWCNTs. Raman analysis confirmed the existence of carbon nanotubes with abundant structural defects of MnO₂ in the composite. The cyclic voltammetry results displayed a high peak current and narrowed over potential towards the reduction of H₂O₂. The sensor displayed a fast response (<5?s), wide linear range (2–1510?μM) and a low limit of detection (0.04?μM) with significant anti-interfering properties, promising for the development of highly sensitive and reproducible biosensors. The three dimensional nanocomposite sensor also exhibited good recovery (> 98%), thus providing a favourable tool for analysis of H₂O₂ in milk samples.     

Transmission electron microscopy studies of thermomechanically control processed multiphase medium-carbon microalloyed steel: Forged, rolled, and low-cycle fatigued microstructures

A ferrite-bainite-martensite (F-B-M) microstructure was produced in a medium-carbon microalloyed (MA) steel through two routes, namely, low-temperature finish forging and rolling, followed by a two-step cooling (TSC) and annealing. Transmission electron microscopy (TEM) was employed to study the microstructural evolution in control forged and rolled material after TSC followed by annealing (TSCA). A TEM investigation was also carried out on samples low-cycle fatigue (LCF) tested at low and high total strain amplitudes of 0.4 and 0.7 pct in case of the forged steel (F-B-M(F)TSCA) and 0.55 and 0.8 pct for the rolled steel (F-B-M(R)TSCA), respectively. Microstructural changes accompanying the LCF testing were identified. The two-step cooled microstructure processed through forging (F-B-M(F)TSC) as well as rolling (F-B-M(R)TSC) revealed a complex multiphase microstructure, along with films and blocks of retained austenite. In both microstructural conditions, vanadium carbide precipitates were too fine to be identified after the TSC treatment. Annealing after TSC produced a stress-free microstructure. The F-B-M(F)TSCA microstructure predominantly consisted of granular/lower bainite, lath martensite, and polygonal ferrite with interlath films as well as blocks of retained austenite, while the F-B-M(R)TSCA microstructure predominantly consisted of lath martensite, granular/lower bainite, and polygonal ferrite with interlath strips/films of retained austenite. Lath martensite content was higher in the F-B-M(R)TSCA condition than in the F-B-M(R)TSCA condition. In both conditions, vanadium carbide precipitates could be seen after annealing. Fatigue-tested F-B-M(F)TSCA microstructure up to a total strain amplitude of 0.4 pct and F-B-M(F)TSCA microstructure up to a total strain amplitude of 0.55 pct were stable. Lath martensite did not undergo deformation and in both microstructural conditions dislocation cell structures were not observed in the ferrite or bainite regions. The interlath retained austenite strips/films played a significant role in preventing the softening during fatigue loading. First, it was stable up to a total strain amplitude of 0.4 and 0.55 pct in the respective microstructures. Second, it underwent heavy deformation during fatigue loading at high total strain amplitudes, thereby accommodating the strain. Fatigue-tested F-B-M(F)TSCA microstructure at a total strain amplitude of 0.7 pct and F-B-M(R)TSCA microstructure at a total strain amplitude of 0.8 pct revealed deformed bainite/martensite laths, dislocation cells, and slip bands in the ferrite regions, which are characteristic features of cyclic softening. The retained austenite transformed to martensite through a strain-induced transformation mechanism and, at that stage, the microstructure contained in addition dislocation-rich bainite and ferrite.     

An improved approach to application-specific power electronicseducation-switch characterization and modeling

An integrated power electronics curriculum has been implemented in the Department of Electrical and Computer Engineering at the University of Illinois, Chicago. This paper describes the development of a set of hands-on laboratory experiments to accompany classroom lectures. Content is based on switching converter topologies and commercial power semiconductor devices. Unlike most experiments, which focus on circuit- or control-level characteristics, our approach emphasizes the circuit-device-load interactions. The concept presented is innovative in that it creates a 3×3 matrix of experiment variation-devices, circuits-control, and machines-loads-with one set of hardware. The lab development is ongoing with future experiments to address three-phase converters and motor control applications. Experiment content is described, as well as the means by which the material has been integrated within the course sequence. Lab station construction and safety issues are also addressed. The experiments require hands-on measurement and circuit connection and complement the established course elements of theory and computer-based circuit modeling. Laboratory experiments and computer simulations collectively provide quantitative evidence of mixed circuit and device optimization     

Application of Sequential Learning Neural Networks to Civil Engineering Modeling Problems

A sequential orthogonal approach to the building and training of a single hidden layer neural network is presented in this paper. The Sequential Learning Neural Network (SLNN) model proposed by Zhang and Morris [1]is used in this paper to tackle the common problem encountered by the conventional Feed Forward Neural Network (FFNN) in determining the network structure in the number of hidden layers and the number of hidden neurons in each layer. The procedure starts with a single hidden neuron and sequentially increases in the number of hidden neurons until the model error is sufficiently small. The classical Gram–Schmidt orthogonalization method is used at each step to form a set of orthogonal bases for the space spanned by output vectors of the hidden neurons. In this approach it is possible to determine the necessary number of hidden neurons required. However, for the problems investigated in this paper, one hidden neuron itself is sufficient to achieve the desired accuracy. The neural network architecture has been trained and tested on two practical civil engineering problems – soil classification, and the prediction o strength and workability of high performance concrete.     

Polarization discrimination of coherently propagating light in turbid media

We describe the use of degree of polarization to discriminate unscattered and weakly scattered light from multiply scattered light in an optically turbid material. We use spatially resolved measurements of the degree of polarization to compare how well linearly and circularly polarized light survives in a sample. Experiments were performed on common tissue phantoms consisting of polystyrene and Intralipid microsphere suspensions and on adipose and arterial tissue. The results indicate that polarization is maintained even after unpolarized irradiance through each sample has been extinguished by several orders of magnitude. The results also show that polarized light propagation in common tissue phantoms is distinctly different from polarized light propagation in the two tissues investigated. Further, these experiments illustrate when polarization is an effective discrimination criterion and when it is not. The potential of a polarization-based discrimination scheme to image through the biological and nonbiological samples investigated here is also discussed.     

Native and oxidized low density lipoproteins modulate mesangial cell apoptosis

Hyperlipidemia has been demonstrated to contribute to hypercellularity of the mesangium in experimental animal models of glomerulosclerosis. We studied whether it also has the potential to convert a hypercellular mesangium into a hypocellular one by inducing mesangial cell (MC) apoptosis. Low density lipoprotein (LDL) enhanced (P < 0.001) mouse mesangial cell (MMC) proliferation at lower concentrations (control, 10.3 +/- 0.3 vs. LDL 100 micrograms/ml, 24.2 +/- 0.3 x 10(4) cells/ml) but augmented (P < 0.001) apoptosis at higher concentrations (control, 5.6 +/- 0.5% vs. LDL, 500 micrograms/ml 26.2 +/- 3.4% apoptotic cells/field). Oxidized (OX) LDL enhanced MMC apoptosis in concentrations of 50 to 200 micrograms/dl. There was a direct relationship between MMC apoptosis and oxidation of LDL as judged by measuring thiobarbituric acid reactive species (TBARS). Since superoxide dismutase (SOD) attenuated (P < 0.001) LDL-induced MMC apoptosis, it seems to be mediated through the generation of free radicals by mesangial cells (control, 4.3 +/- 1.5%; LDL, 200 micrograms/ml, 19.4 +/- 0.5%; LDL + SOD, 8.1 +/- 1.3% apoptotic cells/field). LDL also induced a similar effect on human mesangial cells. These studies were further confirmed by DNA fragment assays and ELISA for programmed cell death. LDL treated cells also showed enhanced mRNA expression for RSG-2, a marker for active cell death. These in vitro results provide a basis for the speculation that LDL has the potential to cause an initial hypercellular and subsequent hypocellular mesangium in the course of the development of glomerulosclerosis.     

Electronic error compensation of a current transformer

A scheme is presented employing two precision resistors and an electronic amplifier for reducing the ratio and phase-angle errors in a current transformer. The amplifier supplies only the error current. The proposed arrangement facilitates the adaptability of inexpensive low ampere-turn c.t.s for calibration work in the laboratory.     

On the various stages of spinodal decomposition in an Al-38 at % Zn alloy

Spinodal decomposition of an Al-38 at % Zn alloy in the temperature range 293 to 573 K has been studied by transmission electron microscopy. Microstructural evidences for the existence of various stages of spinodal decomposition, namely, the initial, the corsening and the particulate stages have been established. The morphological characteristics and the different diffusion regimes under which these stages are operative are explained.