Highway filter drains maintenance management

Across a large part of the UK highways network the carriageway and pavement foundations are drained by Highway Filter Drains (HFDs). A HFD is a linear trench constructed either at the pavement edge or central reserve, fitted with a porous carrier pipe at the base and backfilled with an initially highly porous aggregate material. This arrangement enables the swift removal of surface runoff and subsurface water from the pavement system minimising road user hazards and eliminating risk of structural damage to the pavement sub-base. The highly porous backfill filters throughout its operational life fines washed from the pavement wearing course or adjacent land. HFDs have been found to be prone to collecting near the basal sections (pipe) or surface layers contaminants or detritus that causes the filter media to gradually block. The process has been defined as HFD clogging and it has been found to lead to reduced drainage capacity and potentially severe drop of serviceability. O&M contractual agreements for DBFO projects usually propose in-service and handback requirements for all assets included in the concession portfolio. Different performance thresholds are thus prescribed for pavements, structures, ancillary assets or street lighting. Similar definitions can be retrieved for drainage assets in such agreements, and these include HFDs. Performance metrics are defined though in a generic language and residual life (a key indicator for major assets that usually drives long-term maintenance planning) is prescribed without indicative means to evaluate such a parameter. Most of pavement maintenance is carried out nowadays using proactive management thinking and engineered assessment of benefits and costs of alternative strategies (what-if scenarios). Such a proactive regime is founded upon data driven processes and asset specific ageing / renewal understanding. Within the spectrum of road management, maintenance Life Cycle Costs are usually generated and updated on an annual basis using inventory and condition data linked to a Decision Support Tool (DST). This enables the assessment and optimisation of investment requirements and projection of deterioration and of treatment impacts aligned to continuous monitoring of asset performance. Following this paradigm shift in infrastructure management, a similar structured methodology to optimise HFD maintenance planning is desired and is introduced in this thesis. The work presented enables the identification of proactive maintenance drivers and potential routes in applying a systemised HFD appraisal and monitoring system. An evaluation of Asset Management prerequisites is thus discussed linked to an overview of strategic requirements to establish such a proactive approach. The thesis identifies condition assessment protocols and focuses on developing the means to evaluate deteriorated characteristics of in service drains using destructive and non-destructive techniques. A probabilistic HFD ageing / renewal model is also proposed using Markov chains. This builds upon existing deterioration understanding and links back to current treatment options and impacts. A filter drain decision support toolkit is lastly developed to support maintenance planning and strategy generation

Innovative Methods and Materials in Structural Health Monitoring of Civil Infrastructures

In the past, when elements in sructures were composed of perishable materials, such as wood, the maintenance of houses, bridges, etc., was considered of vital importance for their safe use and to preserve their efficiency. With the advent of materials such as reinforced concrete and steel, given their relatively long useful life, periodic and constant maintenance has often been considered a secondary concern. When it was realized that even for structures fabricated with these materials that the useful life has an end and that it was being approached, planning maintenance became an important and non-negligible aspect. Thus, the concept of structural health monitoring (SHM) was introduced, designed, and implemented as a multidisciplinary method. Computational mechanics, static and dynamic analysis of structures, electronics, sensors, and, recently, the Internet of Things (IoT) and artificial intelligence (AI) are required, but it is also important to consider new materials, especially those with intrinsic self-diagnosis characteristics, and to use measurement and survey methods typical of modern geomatics, such as satellite surveys and highly sophisticated laser tools

DESIGN FOR TESTABILITY AND TEST GENERATION WITH TWO CLOCKS

We propose a novel design for testability method that enhances the controllability of storage elements by use of additional clock lines Our scheme is applicable to synchronous circuits but is otherwise transparent to the designer. The associated area and speed penalties are minimal compared to scan based methods, however, a sequential ATPG system is necessary for test generation. The basic idea Is to use independent clock lines to control disjoint groups of flip-flops. No cyclic path are permitted among the flip-flops of the same group. During testing, a selected group can be made to hold its state by disabling its clock lines In the normal mode, all clock lines carry the same system clock signal. With the appropriate partitioning of flip-flops, the length of the vector sequence produced by the test generator for a fault is drastically reduced. An n-stage binary counter is used for experimental verification of reduction in test length by the proposed technique

Ambiente de simulação para o sistema de exploração robótica subaquática UNEXMIN

Underwater mines exploration is a valued, complex, expensive and time-consuming task. The unstable nature of the underwater environment with lack of visibility and the existence of obstructions create the need for complex navigation software which requires numerous missions and hardware/software validations. When testing and verifying control algorithms for such an operation, a simulation environment can be a very helpful tool. This also includes tools for the development of unmanned vehicle software, algorithm benchmarking and system preliminary validation. The objective in this thesis was to start the development of a simulation platform that can be used when developing and testing control systems for AUV operations. The simulator will include a dynamic model of an AUV in addition to complex world and sensor models such as DVL, IMU, Multibeam, Mechanical Scanning Imaging Sonar (MSIS), cameras, SLS and others. The simulated world includes water graphics, mine meshes, underwater visibility, currents, and hydrodynamics. Control of the robot in simulation is performed by keyboard or joystick over thrusters. The platform must be universal, such that users can implement their own algorithms easily and get immediate simulation results without needing to implement a complete control system. There should also be an easy transition between testing the control system on the simulated AUV and applying it to the real AUV. Robot Operating System (ROS) and Gazebo were used in the development of the platform. The platform with sensors and navigation was validated with real-world tests comparison.A exploração de minas subaquáticas ´e uma tarefa valiosa, complexa, dispendiosa e demorada. A natureza instável do ambiente subaquático, com falta de visibilidade e a existência de obstruções, cria a necessidade de software de navegação complexo, qual requer inúmeras missões e validações de hardware/software. Ao testar e verificar os algoritmos de controle para tal operação, um ambiente de simulação pode ser uma ferramenta muito útil. Isto também inclui ferramentas para o desenvolvimento de software de veículos não tripulados, benchmarking de algoritmos e validação preliminar do sistema. O objetivo desta tese foi iniciar o desenvolvimento de uma plataforma de simulação que possa ser usada no desenvolvimento e teste de sistemas de controle para operações de AUV. O simulador incluirá um modelo dinâmico de um AUV, além de modelos complexos do mundo e sensores, como DVL, IMU, Multibeam, MSIS, câmaras, SLS e outros. O mundo simulado inclui gráficos de ´agua, malhas de minas, visibilidade subaquática, correntes e hidrodinâmica. O controle do robô ´e realizado por teclado ou joystick sob as dinâmicas de propulsão. O simulador deve ser universal, de modo que os usuários possam implementar seus próprios algoritmos facilmente e obter resultados imediatos de simulação sem a necessidade de implementar um sistema de controle completo. Também deve haver uma transição fácil entre testar o sistema de controle no AUV simulado e aplicá-lo ao AUV real. ROS e Gazebo foram usados no desenvolvimento da plataforma. A plataforma com sensores e navegação foi validada com comparação de testes reais

Automatic test pattern generation for asynchronous circuits

The testability of integrated circuits becomes worse with transistor dimensions reaching nanometer scales. Testing, the process of ensuring that circuits are fabricated without defects, becomes inevitably part of the design process; a technique called design for test (DFT). Asynchronous circuits have a number of desirable properties making them suitable for the challenges posed by modern technologies, but are severely limited by the unavailability of EDA tools for DFT and automatic test-pattern generation (ATPG). This thesis is motivated towards developing test generation methodologies for asynchronous circuits. In total four methods were developed which are aimed at two different fault models: stuck-at faults at the basic logic gate level and transistor-level faults. The methods were evaluated using a set of benchmark circuits and compared favorably to previously published work. First, ABALLAST is a partial-scan DFT method adapting the well-known BALLAST technique for asynchronous circuits where balanced structures are used to guide the selection of the state-holding elements that will be scanned. The test inputs are automatically provided by a novel test pattern generator, which uses time frame unrolling to deal with the remaining, non-scanned sequential C-elements. The second method, called AGLOB, uses algorithms from strongly-connected components in graph graph theory as a method for finding the optimal position of breaking the loops in the asynchronous circuit and adding scan registers. The corresponding ATPG method converts cyclic circuits into acyclic for which standard tools can provide test patterns. These patterns are then automatically converted for use in the original cyclic circuits. The third method, ASCP, employs a new cycle enumeration method to find the loops present in a circuit. Enumerated cycles are then processed using an efficient set covering heuristic to select the scan elements for the circuit to be tested.Applying these methods to the benchmark circuits shows an improvement in fault coverage compared to previous work, which, for some circuits, was substantial. As no single method consistently outperforms the others in all benchmarks, they are all valuable as a designer’s suite of tools for testing. Moreover, since they are all scan-based, they are compatible and thus can be simultaneously used in different parts of a larger circuit. In the final method, ATRANTE, the main motivation of developing ATPG is supplemented by transistor level test generation. It is developed for asynchronous circuits designed using a State Transition Graph (STG) as their specification. The transistor-level circuit faults are efficiently mapped onto faults that modify the original STG. For each potential STG fault, the ATPG tool provides a sequence of test vectors that expose the difference in behavior to the output ports. The fault coverage obtained was 52-72 % higher than the coverage obtained using the gate level tests. Overall, four different design for test (DFT) methods for automatic test pattern generation (ATPG) for asynchronous circuits at both gate and transistor level were introduced in this thesis. A circuit extraction method for representing the asynchronous circuits at a higher level of abstraction was also implemented. Developing new methods for the test generation of asynchronous circuits in this thesis facilitates the test generation for asynchronous designs using the CAD tools available for testing the synchronous designs. Lessons learned and the research questions raised due to this work will impact the future work to probe the possibilities of developing robust CAD tools for testing the future asynchronous designs

United States Coast Guard VIDA Job Aids

With the passage of new VIDA regulations, the United States Coast Guard is now tasked with inspecting for environmental compliance on commercial vessels. Our team was tasked with developing a series of job aids that the Coast Guard can use to make these inspections safer, faster, and more accurate than through normal training alone. We accomplished this through codifying the VIDA discharges, interviewing Coast Guard personnel, and gaining feedback on job aid drafts we created. Through our research, we determined a list of criteria that the Coast Guard can use when creating their job aids, both in their content and in their format. Using these criteria, we developed some recommendations on how the Coast Guard can create, implement, and adapt future job aids for environmental inspections

A Lean study to improve the efficiency and flexibility of the product realisation process

This thesis investigates the possible positive effects a Lean study of the, planning, production and development of products, may have on a company’s product realisation process. In an environment where a company needs to satisfy a customer demand for both standard and customised products will induce a wide product range. This can induce a lot of wasteful activities and puts pressure on the product realisation process to be efficient and flexible. The purpose of the thesis was to identify gaps which need to be improved in order to increase the efficiency and flexibility of the product realisation process. In order to study this phenomenon a company that practices both production and development of products, as well as offering both standard and customised products was chosen for a case study. The authors utilised value stream mapping, interviews and observations to establish a great understanding of the company’s activities within the product realisation process. From this, the authors identified gaps that needed to be improved in order to fulfil the standards of ISO 9001 and to increase the efficiency and flexibility within the product realisation process. The study resulted in 15 identified gaps concerning the production and product development departments. Several gaps where chosen for an in-depth study based on their feasibility and potential of improvement. The authors developed several in-depth proposals utilising the Lean philosophy as well as production and inventory control tools, and proven product design techniques. If implemented these proposals would increase the efficiency and flexibility within the product realisation process. The authors suggest that companies should conducting a Lean study of the product realisation process with the purpose to increase the efficiency and flexibility. This will enable a company to identify and improve the proper aspects in order to survive or gain market shares in an environment where the customer demand for standard and customised products needs to be satisfied

A unified method for assembling global test schedules

In order to make a register transfer structure testable, it is usually divided into functional blocks that can be tested independently by various test methods. The test patterns are shifted in or generated autonomously at the inputs of each block. The test responses of a block are compacted or observed at its output register. In this paper a unified method for assembling all the single tests to a global schedule is presented. It is compatible with a variety of different test methods. The described scheduling procedures reduce the overall test time and minimize the number of internal registers that have to be made directly observable

GENERATION OF MULTICOMPONENT POLYMER BLEND MICROPARTICLES USING DROPLET EVAPORATION TECHNIQUE AND MODELING EVAPORATION OF BINARY DROPLET CONTAINING NON-VOLATILE SOLUTE

Recently, considerable attention has been focused on the generation of nano- and micrometer scale multicomponent polymer particles with specifically tailored mechanical, electrical and optical properties. As only a few polymer-polymer pairs are miscible, the set of multicomponent polymer systems achievable by conventional methods, such as melt blending, is severely limited in property ranges. Therefore, researchers have been evaluating synthesis methods that can arbitrarily blend immiscible solvent pairs, thus expanding the range of properties that are practical. The generation of blended microparticles by evaporating a co-solvent from aerosol droplets containing two dissolved immiscible polymers in solution seems likely to exhibit a high degree of phase uniformity. A second important advantage of this technique is the formation of nano- and microscale particulates with very low impurities, which are not attainable through conventional solution techniques. When the timescale of solvent evaporation is lower than that of polymer diffusion and self-organization, phase separation is inhibited within the atto- to femto-liter volume of the droplet, and homogeneous blends of immiscible polymers can be produced. We have studied multicomponent polymer particles generated from highly monodisperse micrordroplets that were produced using a Vibrating Orifice Aerosol Generator (VOAG). The particles are characterized for both external and internal morphology along with homogeneity of the blends. Ultra-thin slices of polymer particles were characterized by a Scanning Electron Microscope (SEM), and the degree of uniformity was examined using an Electron Dispersive X-ray Analysis (EDAX). To further establish the homogeneity of the polymer blend microparticles, differential scanning calorimeter was used to measure the glass transition temperature of the microparticles obtained. A single glass transition temperature was obtained for these microparticles and hence the homogeneity of the blend was concluded. These results have its significance in the field of particulate encapsulation. Also, better control of the phase morphologies can be obtained by simply changing the solvent/solvents in the dilute solutions. Evaporation and drying of a binary droplet containing a solute and a solvent is a complicated phenomenon. Most of the present models do not consider convection in the droplet phase as solvent is usually water which is not very volatile. In considering highly volatile solvents the evaporation is very rapid. The surface of the droplet recedes inwards very fast and there is an inherent convective flow that is established inside the solution droplet. In this dissertation work, a model is developed that incorporates convection inside the droplet. The results obtained are compared to the size obtained from experimental results. The same model when used with an aqueous solution droplet predicted concentration profiles that are comparable to results obtained when convection was not taken into account. These results have significance for more rigorous modeling of binary and multicomponent droplet drying