Anclaje árbol-raíz: Estabilidad de árboles basado en la arquitectura real del sistema árbol-raíz.

Climate change impact on tree stability is often associated with higher risk of wind-throw due to higher frequency and magnitudes of the extremes of climate. Higher lateral loads due to increase in maximum wind and rainfall reduces tree anchorage due to a decrease in soil matric suction and consequently the overall strength in trunk-root-soil. This study made comparisons of the mechanical response of trees with different root architectures using static loading test conducted in the field and numerical analysis of laser-scanned root systems. For this case, Samanea saman, Khaya senegalensis and Syzygium grande were the tree species selected and analysed. The tree-root system models consisted of root system architectures obtained using 3D-laser scanning. A parametric analysis was conducted by varying the modulus of elasticity of the soil (Es) from 2.5 to 25 MPa and the results were compared with the static load tests to obtain the overall mechanical responses of the soil-tree root systems. The results showed important dependencies of the mechanical responses of the soil-tree root with the lateral load magnitudes with respect to the root architecture. The numerical models were also able to estimate the effective leeward and windward anchorage zones with different soil elastic modulus and rooting architectures to define the Tree Protection Zone (TPZ).Maestrí

Deconstructing the Art of Physical Weed Control

Farmers adjust physical weed control (PWC) tools to optimize efficacy based on observations of weeds, the crop, and soil conditions. These many variables make PWC research challenging. To study PWC tool settings more closely, we constructed a soil bin with a mobile tool carriage inside of a heated glasshouse. The soil bin was 2 m wide by 12 m long by 1 m high, with a tool carriage that can operate at 0.4 to 19.0 km h-1. Tool angle, spacing, depth, and speed can all be precisely adjusted from the tool carriage and control panel. The goal of this research was to take the art out of PWC and provide farmers with researched based recommendations, as well as provide researchers with new methods on how to test PWC tools. The aim of chapter one was to develop methods for a high-throughput system in a controlled environment with artificial weeds (AWs) to test PWC tools. Methods were developed using a simple tine weeder, wooden golf tees as AWs, and a soil bin. The tine weeder was chosen for methods development because it offers uniform soil disturbance and appears to have both uprooting and burial mode of action. Tine speed, angle, and depth were evaluated in both soil bin and field experiments. Tool efficacy from the soil bin were qualitatively compared to efficacy results using surrogate weeds in the field. Results suggest that the simplified conditions of the soil bin system may be useful to test and prioritize tool settings or adjustments for field studies. Chapter two is about determining whether testing PWC tools in a controlled environment using a soil bin system, reflects treatment effects found in the field. A finger weeder was used and settings of angle, spacing, and speed were tested. The three angles tested were hilling (68o), standard (90o), and scrubbing (108o) with three spacings of 0.6 cm overlap, 0.0 cm fingers touching, and 2.5 cm gap. These angles and spacings were tested in a full factorial design with artificial crops (ACs, 6 mm dia. by 152 mm-long wooden dowels) and AWs (70 mm-long wooden golf tees). Three speeds were tested to represent speeds typical for walking (4 km h-1), tractor cultivating (7 km h-1), and a tractor with a camera guidance system (9 km h-1). Experiments of angle, spacing and speed were replicated in the field. Hilling (68o) caused the greatest efficacy in the soil bin (78%) and in the field (62%). As spacing decreased, efficacy and AC mortality increased in the soil bin, but surprisingly, in the field, there was no difference. In the soil bin, higher speeds of 7 and 9 km h-1 increased efficacy by 77% when compared to 4 km h-1. In the field however, no significant effects were detected between speeds. We conclude that the soil bin is a promising research tool for testing PWC tools

Evaluation of a Low-Cost Photogrammetric System for the Retrieval of 3D Tree Architecture

\ua9 Author(s) 2023.Reconstruction of major branches of a tree is an important first step for the monitoring of tree sway and assessment of structural stability. Photogrammetric systems can provide a low-cost alternative for the acquisition of three-dimensional data, while also enabling long-term monitoring of a tree of interest. This study introduces a low-cost photogrammetric system based on two Raspberry Pi cameras, which is used to reconstruct the tree architecture for the purpose of stability monitoring. Images of five trees are taken at a range of distances and the resulting point clouds are evaluated in terms of point density and distribution with the reference to TLS. While the photogrammetric point clouds are sparse, it was found that they are capable of reconstructing the tree trunk and lower-order branches, which are most relevant for sway monitoring and tree stability assessment. The most optimal distance for the reconstruction of the relevant branches was found to be 9-10 m, with a baseline of 120 cm

Single-crystalline PbTe film growth through reorientation

Heteroepitaxy enables the engineering of novel properties, which do not exist in a single material. Two principle growth modes are identified for material combinations with large lattice mismatch, Volmer-Weber and Stranski-Krastanov. Both lead to the formation of three-dimensional islands, hampering the growth of flat defect-free thin films. This limits the number of viable material combinations. Here, we report a distinct growth mode found in molecular beam epitaxy of PbTe on InP initiated by pre-growth surface treatments. Early nucleation forms islands analogous to the Volmer-Weber growth mode, but film closure exhibits a flat surface with atomic terracing. Remarkably, despite multiple distinct crystal orientations found in the initial islands, the final film is single-crystalline. This is possible due to a reorientation process occurring during island coalescence, facilitating high quality heteroepitaxy despite the large lattice mismatch, difference in crystal structures and diverging thermal expansion coefficients of PbTe and InP. This growth mode offers a new strategy for the heteroepitaxy of dissimilar materials and expands the realm of possible material combinations

Are We Driving Strategic Results or Metric Mania? Evaluating Performance in the Public Sector

A strategy is irrelevant if you cannot implement it. That is the collective realization of public and private leaders after decades of obsession with strategy and strategic thinking. That realization has led to a voracious market for ideas on execution, alignment around strategy and predictable achievement of strategic results. Many performance management systems or tools, all meant to help organizational leaders implement their strategic goals and objectives, fail to provide results. We suggest a framework in which strategic and operational goals can be translated into a handful of meaningful metrics that we define as whole goals. Whole goals can then used to drive decision-making and to hold leadership accountable for achieving measurable results. We believe the ability of a public organization to measure and evaluate its performance is of critical importance if today’s leaders and managers are expected to promote successful execution of organizational strategic goals and objectives

An automated railway system : railway network automation for Bangladesh railway

This thesis report is submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Electrical and Electronic Engineering, 2014.While trains are convenient for travel and for transporting goods, they have become a riskier mode of transport over recent years. At present time, a large number of accidents have occurred due to railway mishaps in Bangladesh. Mismanaged railway crossings and faulty rail lines are the principle reasons behind the accidents. Moreover, Bangladesh Railway has attributed a huge sector of those losses to massive manpower and maintenance expenses it engulfs. Both the problems can be resolved by an intelligent unmanned railway introduced in this paper, which will not only reduce the risk of human lives but also a huge amount of public property. The total system is an integration of a few stand-alone sub-systems powered by micro-controllers which perform simultaneously by synchronizing the data to improve the safety and efficiency of the railway transport in different sectors. A part of the system is a completely unmanned crossing system, which ensures the safe crossing of a train in the busy city areas. Sensing the flaws in the railway tracks is also included in this system. This research depends on microcontroller based subsystems to reduce the complexity, uncertainty and cost. Total system is monitored and visualized in custom (Google maps) map which shows the train’s position, operation mode and safety status in the authority unit. The system uses modern communication (i.e. GSM, GPRS) and navigation techniques (i.e. GPS) to create a safer and financially efficient system

Superfast broadband: the future is in your hands

The National Broadband Network (NBN) will deliver a comprehensive upgrade to Australia’s national broadband infrastructure. This will be of profound importance to Australia’s long-term productivity agenda. This paper, commissioned by Vodafone Australia, assesses new opportunities for the NBN. In particular, we examine how the growth of mobile services has transformed the telecommunications industry and how NBN has the potential to dramatically improve mobile telecommunications. It makes the case that the NBN, far from becoming redundant due to the explosion in mobile internet access, is in fact crucial to delivering better mobile services to both regional and urban areas without any significant increases in cost. It argues that the recent development of small mobile base stations (able to be placed on lampposts for example), connected to the NBN, can significantly increase and improve mobile coverage in both urban and regional Australia. This has the potential to radically reshape Australia’s economic and social future