A study to support agile methods more effectively through traceability

Traceability is recognized to be important for supporting agile development processes. However, after analyzing many of the existing traceability approaches it can be concluded that they strongly depend on traditional development process characteristics. Within this paper it is justified that this is a drawback to support adequately agile processes. As it is discussed, some concepts do not have the same semantics for traditional and agile methodologies. This paper proposes three features that traceability models should support to be less dependent on a specific development process: (1) user-definable traceability links, (2) roles, and (3) linkage rules. To present how these features can be applied, an emerging traceability metamodel (TmM) will be used within this paper. TmM supports the definition of traceability methodologies adapted to the needs of each project. As it is shown, after introducing these three features into traceability models, two main advantages are obtained: 1) the support they can provide to agile process stakeholders is significantly more extensive, and 2) it will be possible to achieve a higher degree of automation. In this sense it will be feasible to have a methodical trace acquisition and maintenance process adapted to agile processes.     

SPAWNING OF THE ENDANGERED AUSTRALIAN LUNGFISH (NEOCERATODUS FORSTERI) IN A HEAVILY REGULATED RIVER: A PULSE FOR LIFE

The Australian lungfish is an endangered native species currently protected under various state, federal and international agreements. Scarce information on their early life history is available due to the absence of juveniles collected in the wild. This has led to concerns about the sustainability of the species and become a driver for the conservation effort for Australian lungfish. This study aimed to consolidate knowledge on the critical hydraulic habitat requirements of this species within a water resource management context. In this study, spawning of Australian lungfish was found to be a seasonal strategy that is highly reliant on a variable low‐flow regime within riverine habitat. Suitable conditions for spawning were characterized by small flow events in early‐to‐mid spring when water temperatures are between 18 and 28 °C, leading to oviposition on short dense macrophytes in shallow water. Importantly, many of the key environmental factors driving the ecological response are manageable through existing water resource infrastructure. Specifically, releases from water storages within the current distribution of Australian lungfish should mimic the natural inflow and temperature regime within the spawning period, and also provide suitable riverine habitat within projected full supply limits. Copyright © 2012 John Wiley & Sons, Ltd.     

Primal-Dual Monotone Kernel Regression

This paper considers the estimation of monotone nonlinear regression functions based on Support Vector Machines (SVMs), Least Squares SVMs (LS-SVMs) and other kernel machines. It illustrates how to employ the primal-dual optimization framework characterizing LS-SVMs in order to derive a globally optimal one-stage estimator for monotone regression. As a practical application, this letter considers the smooth estimation of the cumulative distribution functions (cdf), which leads to a kernel regressor that incorporates a Kolmogorov–Smirnoff discrepancy measure, a Tikhonov based regularization scheme and a monotonicity constraint.     

Evolution of collaboration and optimization of impact: self-organization in multinational research

Scientometrics - The expanding presence of multinational research teams highlights the importance of characterizing the outcomes of international collaboration. Herein, we characterize the...     

Backstepping - Sliding Mode Controllers Applied to a Fixed-Wing UAV

This paper deals with the design of five controllers, based on Backstepping and Sliding Modes, which are applied to a fixed-wing unmanned aerial vehicle (UAV). We are interested to realize a comparative analysis of such methodologies in order to know what controller has a better performance when they are used to the autonomous flight (altitude, yaw and roll) of a fixed-wing UAV. The designed controllers are: Backstepping, Sliding Mode control (SMC), Backstepping with Sliding Mode control, Backstepping with two Sliding Mode control, and Backstepping with high order Sliding Mode (HOSM) control. Simulation results are obtained in order to analyze the controllers performance. We finally present an experimental result, in open-loop, with the purpose of validate the magnitude of the control signals obtained in the simulations.     

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.     

Performance Evaluation of a Multicell Topology Implemented With Single-Phase Nonregenerative Cells Under Unbalanced Supply Voltages

The analysis of a multicell topology that is implemented with single-phase nonregenerative cells under an unbalanced ac mains is presented. The study shows that the topology naturally compensates most of the voltage unbalance; for instance, for a 100% voltage unbalance in the ac mains, just 32% reaches the load. For critical applications, a feedforward control technique is proposed in order to compensate the remaining unbalance at the load side. The resulting topology, in combination with the proposed strategy, reduces near to zero the load fundamental voltage unbalance, while the input current unbalance and distortion are also improved. A theoretical analysis that is based on symmetrical components and the experimental results confirm the theoretical considerations.     

Selective Harmonic Elimination in Multimodule Three-Phase Current-Source Converters

Modular current-source converter (MCSC) structures can enhance the current capacity and improve the power quality of converters in medium-voltage pulsewidth-modulated applications. An MCSC uses individual three-phase modules in a shunt connection to share the total power in a symmetrical manner. The modulation of these units is normally done using optimized patterns such as selective harmonic elimination patterns. However, the optimization is usually performed at the module level. This paper proposes a modulation technique that optimizes the operation of a complete MCSC taking into account all $P$ modules. Thus, from the injected ac current, we remove $P$ times the number of harmonics as compared with the conventional approach using the same switching frequency. A complete mathematical formulation and experimental results validate the proposed approach.