Monitoring system for long-distance pipelines subject to destructive attack

In an era of terrorism, it is important to protect critical pipeline infrastructure, especially in countries where life is strongly dependent on water and the economy on oil and gas. Structural health monitoring (SHM) using acoustic waves is one of the common solutions. However, considerable prior work has shown that pipes are cylindrical acoustic waveguides that support many dispersive, lossy modes; only the torsional T(0, 1) mode has zero dispersion. Although suitable transducers have been developed, these typically excite several modes, and even if they do not, bends and supports induce mode conversion. Moreover, the high-power transducers that could in principle be used to overcome noise and attenuation in long distance pipes present an obvious safety hazard with volatile products, making it difficult to distinguish signals and extract pipeline status information. The problem worsens as the pipe diameter increases or as the frequency rises (due to the increasing number of modes), if the pipe is buried (due to rising attenuation), or if the pipe carries a flowing product (because of additional acoustic noise). Any system is therefore likely to be short-range. This research proposes the use of distributed active sensor network to monitor long-range pipelines, by verifying continuity and sensing small disturbances. A 4-element cuboid Electromagnetic Acoustic Transducer (EMAT) is used to excite the longitudinal L(0,1) mode. Although the EMAT also excites other slower modes, long distance propagation allows their effects to be separated. Correlation detection is exploited to enhance signal-to-noise ratio (SNR), and code division multiplexing access (CDMA) is used to distinguish between nodes in a multi-node system. An extensive numerical search for multiphase quasi-orthogonal codes for different user numbers is conducted. The results suggest that side lobes degrade performance even with the highest possible discrimination factor. Golay complementary pairs (which can eliminate the side lobes completely, albeit at the price of a considerable reduction in speed) are therefore investigated as an alternative. Pipeline systems are first reviewed. Acoustic wave propagation is described using standard theory and a freeware modeling package. EMAT modeling is carried out by numerical calculation of electromagnetic fields. Signal propagation is investigated theoretically using a full system simulator that allows frequency-domain description of transducers, dispersion, multi-mode propagation, mode conversion and multiple reflections. Known codes for multiplexing are constructed using standard algorithms, and novel codes are discovered by an efficient directed search. Propagation of these codes in a dispersive system is simulated. Experiments are carried out using small, unburied air-filled copper pipes in a frequency range where the number of modes is small, and the attenuation and noise are low. Excellent agreement is obtained between theory and experiment. The propagation of pulses and multiplexed codes over distances up to 200 m are successfully demonstrated, and status changes introduced by removable reflectors are detected.Open Acces

Optimisation of Car Park Designs

The problem presented by ARUP to the UK Study Group 2014 was to investigate methods for maximising the number of car parking spaces that can be placed within a car park. This is particularly important for basement car parks in residential apartment blocks or offices where parking spaces command a high value. Currently the job of allocating spaces is done manually and is very time intensive. The Study Group working on this problem split into teams examining different aspects of the car park design process There were three approaches taken. These approaches include a so-called "tile-and-trim" method in which an optimal layout of cars from an `infinite car park' are overlaid onto the actual car park domain; adjustments are then made to accommodate access from one lane to the next. A second approach seeks to develop an algorithm for optimising the road within a car park on the assumption that car parking spaces should fill the space and that any space needs to be adjacent to the network. A third similar approach focused on schemes for assessing the potential capacity of a small selection of specified road networks within the car park to assist the architect in selecting the optimal road network(s). The problem is a variant of the "bin packing" problem, well known in computer science. It is further complicated by the fact that two different classes of item need to be packed (roads and cars), with both local (immediate access to a road) and global (connectivity of the road network) constraints. Bin-packing is known to be NP-hard, and hence the problem at hand has at least this level of computational complexity. None of the approaches produced a complete solution to the problem posed. Indeed, it was quickly determined by the group that this was a very hard problem (a view reinforced by the many different possible approaches considered) requiring far longer than a week to really make significant progress. All approaches rely to differing degrees on optimisation algorithms which are inherently unreliable unless designed specifically for the intended purpose. It is also not clear whether a relatively simple automated computer algorithm will be able to "beat the eye of the architect"; additional sophistication may be required due to subtle constraints. Apart from determining that the problem is hard, positive outcomes have included: Determining that parking perpendicular to the road in long aisles provides the most efficient packing of cars. Provision of code which "tiles and trims" from an infinite car park onto the given car park with interactive feedback on the number of cars in the packing. Provision of code for optimal packing in a parallel-walled car park. Methods for optimising a road within a given domain based on developing cost functions ensuring that cars fill the car park and have access to the road. Provision of code for optimising a single road in a given (square) space. Description of methods for assessing the capacity of a car park for a set of given road network in order to select optimal road networks. Some ideas for developing possible solutions further

Planar Open Rectangle-of-Influence Drawings

A straight line drawing of a graph is an open weak rectangle-of-influence (RI) drawing, if there is no vertex in the relative interior of the axis parallel rectangle induced by the end points of each edge. Despite recent interest of the graph drawing community in rectangle-of-influence drawings, no algorithm is known to test whether a graph has a planar open weak RI-drawing, not even for inner triangulated graphs. In this thesis, we have two major contributions. First we study open weak RI-drawings of plane graphs that must have a non-aligned frame, i.e., the graph obtained from removing the interior of every filled triangle is drawn such that no two vertices have the same coordinate. We introduce a new way to assign labels to angles, i.e., instances of vertices on faces. Using this labeling, we provide necessary and sufficient conditions characterizing those plane graphs that have open weak RI-drawings with non-aligned frame. We also give a polynomial algorithm to construct such a drawing if one exists. Our second major result is a negative result: deciding if a planar graph (i.e., one where we can choose the planar embedding) has an open weak RI-drawing is NP-complete. NP-completeness holds even for open weak RI-drawings with non-aligned frames

Bus-driven floorplanning.

Law Hoi Ying.Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.Includes bibliographical references (leaves 101-106).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- VLSI Design Cycle --- p.2Chapter 1.2 --- Physical Design Cycle --- p.6Chapter 1.3 --- Floorplanning --- p.10Chapter 1.3.1 --- Floorplanning Objectives --- p.11Chapter 1.3.2 --- Common Approaches --- p.12Chapter 1.3.3 --- Interconnect-Driven Floorplanning --- p.14Chapter 1.4 --- Motivations and Contributions --- p.15Chapter 1.5 --- Organization of the Thesis --- p.17Chapter 2 --- Literature Review on 2D Floorplan Representations --- p.18Chapter 2.1 --- Types of Floorplans --- p.18Chapter 2.2 --- Floorplan Representations --- p.20Chapter 2.2.1 --- Slicing Floorplan --- p.21Chapter 2.2.2 --- Non-slicing Floorplan --- p.22Chapter 2.2.3 --- Mosaic Floorplan --- p.30Chapter 2.3 --- Summary --- p.35Chapter 3 --- Literature Review on 3D Floorplan Representations --- p.37Chapter 3.1 --- Introduction --- p.37Chapter 3.2 --- Problem Formulation --- p.38Chapter 3.3 --- Previous Work --- p.38Chapter 3.4 --- Summary --- p.42Chapter 4 --- Literature Review on Bus-Driven Floorplanning --- p.44Chapter 4.1 --- Problem Formulation --- p.44Chapter 4.2 --- Previous Work --- p.45Chapter 4.2.1 --- Abutment Constraint --- p.45Chapter 4.2.2 --- Alignment Constraint --- p.49Chapter 4.2.3 --- Bus-Driven Floorplanning --- p.52Chapter 4.3 --- Summary --- p.53Chapter 5 --- Multi-Bend Bus-Driven Floorplanning --- p.55Chapter 5.1 --- Introduction --- p.55Chapter 5.2 --- Problem Formulation --- p.56Chapter 5.3 --- Methodology --- p.57Chapter 5.3.1 --- Shape Validation --- p.58Chapter 5.3.2 --- Bus Ordering --- p.65Chapter 5.3.3 --- Floorplan Realization --- p.72Chapter 5.3.4 --- Simulated Annealing --- p.73Chapter 5.3.5 --- Soft Block Adjustment --- p.75Chapter 5.4 --- Experimental Results --- p.75Chapter 5.5 --- Summary --- p.77Chapter 6 --- Bus-Driven Floorplanning for 3D Chips --- p.80Chapter 6.1 --- Introduction --- p.80Chapter 6.2 --- Problem Formulation --- p.81Chapter 6.3 --- The Representation --- p.82Chapter 6.3.1 --- Overview --- p.82Chapter 6.3.2 --- Review of TCG --- p.83Chapter 6.3.3 --- Layered Transitive Closure Graph (LTCG) --- p.84Chapter 6.3.4 --- Aligning Blocks --- p.85Chapter 6.3.5 --- Solution Perturbation --- p.87Chapter 6.4 --- Simulated Annealing --- p.92Chapter 6.5 --- Soft Block Adjustment --- p.92Chapter 6.6 --- Experimental Results --- p.93Chapter 6.7 --- Summary --- p.94Chapter 6.8 --- Acknowledgement --- p.95Chapter 7 --- Conclusion --- p.99Bibliography --- p.10

Proceedings of the 9th Arab Society for Computer Aided Architectural Design (ASCAAD) international conference 2021 (ASCAAD 2021): architecture in the age of disruptive technologies: transformation and challenges.

The ASCAAD 2021 conference theme is Architecture in the age of disruptive technologies: transformation and challenges. The theme addresses the gradual shift in computational design from prototypical morphogenetic-centered associations in the architectural discourse. This imminent shift of focus is increasingly stirring a debate in the architectural community and is provoking a much needed critical questioning of the role of computation in architecture as a sole embodiment and enactment of technical dimensions, into one that rather deliberately pursues and embraces the humanities as an ultimate aspiration