A Tabu Search Based Approach for Graph Layout

This paper describes an automated tabu search based method for drawing general graph layouts with straight lines. To our knowledge, this is the first time tabu methods have been applied to graph drawing. We formulated the task as a multi-criteria optimization problem with a number of metrics which are used in a weighted fitness function to measure the aesthetic quality of the graph layout. The main goal of this work is to speed up the graph layout process without sacrificing layout quality. To achieve this, we use a tabu search based method that goes through a predefined number of iterations to minimize the value of the fitness function. Tabu search always chooses the best solution in the neighbourhood. This may lead to cycling, so a tabu list is used to store moves that are not permitted, meaning that the algorithm does not choose previous solutions for a set period of time. We evaluate the method according to the time spent to draw a graph and the quality of the drawn graphs. We give experimental results applied on random graphs and we provide statistical evidence that our method outperforms a fast search-based drawing method (hill climbing) in execution time while it produces comparably good graph layouts.We also demonstrate the method on real world graph datasets to show that we can reproduce similar results in a real world setting

Algorithm for fuel conservative horizontal capture trajectories

A real time algorithm for computing constant altitude fuel-conservative approach trajectories for aircraft is described. The characteristics of the trajectory computed were chosen to approximate the extremal trajectories obtained from the optimal control solution to the problem and showed a fuel difference of only 0.5 to 2 percent for the real time algorithm in favor of the extremals. The trajectories may start at any initial position, heading, and speed and end at any other final position, heading, and speed. They consist of straight lines and a series of circular arcs of varying radius to approximate constant bank-angle decelerating turns. Throttle control is maximum thrust, nominal thrust, or zero thrust. Bank-angle control is either zero or aproximately 30 deg

Prediction of Search Targets From Fixations in Open-World Settings

Previous work on predicting the target of visual search from human fixations only considered closed-world settings in which training labels are available and predictions are performed for a known set of potential targets. In this work we go beyond the state of the art by studying search target prediction in an open-world setting in which we no longer assume that we have fixation data to train for the search targets. We present a dataset containing fixation data of 18 users searching for natural images from three image categories within synthesised image collages of about 80 images. In a closed-world baseline experiment we show that we can predict the correct target image out of a candidate set of five images. We then present a new problem formulation for search target prediction in the open-world setting that is based on learning compatibilities between fixations and potential targets

Automation of On-Board Flightpath Management

The status of concepts and techniques for the design of onboard flight path management systems is reviewed. Such systems are designed to increase flight efficiency and safety by automating the optimization of flight procedures onboard aircraft. After a brief review of the origins and functions of such systems, two complementary methods are described for attacking the key design problem, namely, the synthesis of efficient trajectories. One method optimizes en route, the other optimizes terminal area flight; both methods are rooted in optimal control theory. Simulation and flight test results are reviewed to illustrate the potential of these systems for fuel and cost savings

Simple models and concepts as tools for the study of sustained soil productivity in long-term experiments. II. Crop nutrient equivalents, balanced supplies of available nutrients, and NPK triangles

Two NPK factorial trials, one in Vietnam and one in The Netherlands were (re-)analyzed to find causes of success or failure with regard to sustained soil productivity, using the concept of crop nutrient equivalents (CNE). A (k)CNE is the quantity of a nutrient that, under conditions of balanced nutrition, has the same effect on yield as 1 (k)g of nitrogen. The percentages the nutrients take in the (k)CNE sum of N, P and K are plotted along the sides of a triangle. Soil, crop and input NPK are indicated in the triangle. Balanced crop NPK is found in the centre of the triangle, and required NPK inputs are on a straight line in the extension of the line trough the point of soil NPK and the centre. Experimental inputs were compared with inputs required for balanced NPK. In Vietnam, responses to P and soil available N:P:K pointed to severe shortage of P. Rice yields increased over time in dry but not in wet seasons. The lower yields in wet seasons were ascribed to insufficiently long periods between the dry and the next wet seasons for replenishment of labile soil P. In the Netherlands, four crops were grown in rotation on a former sea bottom. Only N had a strong effect on yield. Soil available N:P:K revealed low N, very high K and medium P. Recovery of fertilizer N was high because of capillary rise of groundwater and absence of leaching. In both trials, first-season chemical crop analysis would directly have detected disproportions of soil available N, P and K. This knowledge could have improved the experimental designs, optimized nutrient use efficiency and minimized losses of N and K to the environmen