Optimizing construction of scheduled data flow graph for on-line testability

The objective of this work is to develop a new methodology for behavioural synthesis using a flow of synthesis, better suited to the scheduling of independent calculations and non-concurrent online testing. The traditional behavioural synthesis process can be defined as the compilation of an algorithmic specification into an architecture composed of a data path and a controller. This stream of synthesis generally involves scheduling, resource allocation, generation of the data path and controller synthesis. Experiments showed that optimization started at the high level synthesis improves the performance of the result, yet the current tools do not offer synthesis optimizations that from the RTL level. This justifies the development of an optimization methodology which takes effect from the behavioural specification and accompanying the synthesis process in its various stages. In this paper we propose the use of algebraic properties (commutativity, associativity and distributivity) to transform readable mathematical formulas of algorithmic specifications into mathematical formulas evaluated efficiently. This will effectively reduce the execution time of scheduling calculations and increase the possibilities of testability

Development of an ontology supporting failure analysis of surface safety valves used in Oil & Gas applications

Treball desenvolupat dins el marc del programa 'European Project Semester'.The project describes how to apply Root Cause Analysis (RCA) in the form of a Failure Mode Effect and Criticality Analysis (FMECA) on hydraulically actuated Surface Safety Valves (SSVs) of Xmas trees in oil and gas applications, in order to be able to predict the occurrence of failures and implement preventive measures such as Condition and Performance Monitoring (CPM) to improve the life-span of a valve and decrease maintenance downtime. In the oil and gas industry, valves account for 52% of failures in the system. If these failures happen unexpectedly it can cause a lot of problems. Downtime of the oil well quickly becomes an expensive problem, unscheduled maintenance takes a lot of extra time and the lead-time for replacement parts can be up to 6 months. This is why being able to predict these failures beforehand is something that can bring a lot of benefits to a company. To determine the best course of action to take in order to be able to predict failures, a FMECA report is created. This is an analysis where all possible failures of all components are catalogued and given a Risk Priority Number (RPN), which has three variables: severity, detectability and occurrence. Each of these is given a rating between 0 and 10 and then the variables are multiplied with each other, resulting in the RPN. The components with an RPN above an acceptable risk level are then further investigated to see how to be able to detect them beforehand and how to mitigate the risk that they pose. Applying FMECA to the SSV mean breaking the system down into its components and determining the function, dependency and possible failures. To this end, the SSV is broken up into three sub-systems: the valve, the actuator and the hydraulic system. The hydraulic system is the sub-system of the SSV responsible for containing, transporting and pressurizing of the hydraulic fluid and in turn, the actuator. It also contains all the safety features, such as pressure pilots, and a trip system in case a problem is detected in the oil line. The actuator is, as the name implies, the sub-system which opens and closes the valve. It is made up of a number of parts such as a cylinder, a piston and a spring. These parts are interconnected in a number of ways to allow the actuator to successfully perform its function. The valve is the actual part of the system which interacts with the oil line by opening and closing. Like the actuator, this sub-system is broken down into a number of parts which work together to perform its function. After breaking down and defining each subsystem on a functional level, a model was created using a functional block diagram. Each component also allows for the defining of dependencies and interactions between the different components and a failure diagram for each component. This model integrates the three sub-systems back into one, creating a complete picture of the entire system which can then be used to determine the effects of different failures in components to the rest of the system. With this model completed we created a comprehensive FMECA report and test the different possible CPM solutions to mitigate the largest risks

Advanced gearbox technology

An advanced 13,000 HP, counterrotating (CR) gearbox was designed and successfully tested to provide a technology base for future designs of geared propfan propulsion systems for both commercial and military aircraft. The advanced technology CR gearbox was designed for high efficiency, low weight, long life, and improved maintainability. The differential planetary CR gearbox features double helical gears, double row cylindrical roller bearings integral with planet gears, tapered roller prop support bearings, and a flexible ring gear and diaphragm to provide load sharing. A new Allison propfan back-to-back gearbox test facility was constructed. Extensive rotating and stationary instrumentation was used to measure temperature, strain, vibration, deflection and efficiency under representative flight operating conditions. The tests verified smooth, efficient gearbox operation. The highly-instrumented advanced CR gearbox was successfully tested to design speed and power (13,000 HP), and to a 115 percent overspeed condition. Measured CR gearbox efficiency was 99.3 percent at the design point based on heat loss to the oil. Tests demonstrated low vibration characteristics of double helical gearing, proper gear tooth load sharing, low stress levels, and the high load capacity of the prop tapered roller bearings. Applied external prop loads did not significantly affect gearbox temperature, vibration, or stress levels. Gearbox hardware was in excellent condition after the tests with no indication of distress

SUPPORTING FUNCTIONALITY-BASED DESIGN IN COMPUTER-AIDED DESIGN SYSTEMS

Designs are conceptualized in terms of the functions they need to accomplish. The need for a new product design arises as a result of the identification of a new functionality to be accomplished by the product. That is, design is functionality driven. However, existing CAD tools are not equipped to capture functionality or reason in such a fashion to support design for product functionality. This research proposes a new design formalism to enable functionality-driven design of mechanically engineered products. This procedure provides a methodology that allows a designer to model product functionality and to carry out conceptual design with the aid of a computer. It also serves as a bridging tool between the conceptual design phase and detailed design phase of a product. Thus, the primary objective of this research is to develop a methodology that will support the following activities in CAD systems: functionality modeling, functionality data structuring, and form conceptualization.The functionality modeling methodology developed in this work includes the use of operands, operators, and coupling bonds to describe product functionality in CAD systems. The Universal Modeling Language (an object-oriented programming technique) is used to model product functionality in computer systems. The tools developed in this research provide a means of modeling and propagating product functionality information to downstream design activities. The propagation of functionality as a constraint is achieved using Extensible Markup Language (XML) data files. These tools also provide a mechanism for verifying and enforcing constraints on solid CAD models. The functionality definition interface is implemented with a customized Microsoft Visio graphics engine.The tools developed in this research provide a means of modeling and propagating product functionality information to downstream design activities. It also provides a mechanism for verifying and enforcing constraints on solid CAD models. The functionality definition interface is implemented with a customized Microsoft Visio graphics engine

Increasing System Test Coverage in Production Automation Systems

An approach is introduced, which supports a testing technician in the identification of possibly untested behavior of control software of fully integrated automated production systems (aPS). Based on an approach for guided semi-automatic system testing, execution traces are recorded during testing, allowing a subsequent coverage assessment. As the behavior of an aPS is highly dependent on the software, omitted system behavior can be identified and assessed for criticality. Through close cooperation with industry, this approach represents the first coverage assessment approach for system testing in production automation to be applied on real industrial objects and evaluated by industrial experts

Non-linear finite element analysis led design of a novel aircraft seat against certification specifications (CS 25.561)

Seeking to quench airliners’ unending thirst for lightweight, reliable and more comfortable seating solutions, designers are developing a new generation of slim economy – class seats. Challenge in front of the designers is to carve out additional “living space”, as well as to give a “lie – flat” experience to air travellers with strict adherence to safety regulations. Present research tries to address all these industry needs through an innovative and novel “Sleep Seat”. A generous angle of recline (40 degree), movement of “Seat Pan” along the gradient, fixed outer shell of backrest, and unique single “Forward Beam” design distinguishes “Sleep Seat” form current generation seats. It is an ultralightweight design weighing 8kg (typical seat weight is 11kg). It satisfies “Generic Requirements (GR2)” which ensures “Comfort in Air”. It will be a “16g” seat, means it can sustain the “Emergency landing” loads as specified by “Certification Specifications (CS 25.561 and CS 25.562)”. For present research, only CS 25.561 has been considered. Since, the design of “Sleep Seat” is still in its conceptual phase, it is not possible to build the prototypes and their physical testing, due to costs and time involved. “Finite Element Analysis (FEA)” is a useful tool to predict the response of the structure when subjected to real life loads. Hence, the aim of research being undertaken is to develop a detailed FE model of the complete seat structure, which will help designers to identify potential weak areas and to compare different design concepts virtually, thereby reducing the development cycle time. In order to avoid handling of large number of design variables; major load carrying members (called Primary Load Path) i.e. Forward beam and leg; are designed for the most critical “Forward 9g” loads; using FEA results as a basis. A robust framework to verify the FEA results is developed. “Sequential Model Development Approach”; which builds the final, detailed FE model starting from preliminary model (by continuously updating the FE model by addition of details that are backed up by pilot studies); resulted in a FE model which could predict the stress induced in each of the components for applied CS 25.561 loads along with “Seat Interface Loads”. The “Interface Load” is the force exerted by the seat design on the floor and is one of the main contributing factors in seat design. “Optistruct” is used as a solver for linear static FEA, whereas “Abaqus / Standard” is used for non-linear FEA. Stepwise methodologies for mesh sensitivity study, modelling of bolt-preload, representing bolted joint in FEA, preventing rigid body motion, and obtaining a converged solution for non-linear FEA are developed during this research. Free-Shape Optimisation is used to arrive at a final design of Seat-leg. All the findings and steps taken during this are well documented in this report. Finally, a detailed FE model (involving all the three non-linearities : Contact, material and geometric) of the complete seat structure was analysed for the loads taken from CS 25.561, and it was found that design of “Forward beam” and leg are safe against CS 25.561. Therefore, all the aims and objectives outlined for this research were accomplished. For future work, first area to look for, would be validation of present FEA results by experimental testing. FE model to simulate dynamic loads CS 25.562 can be developed followed by design improvements and optimisation

STUDIES ON GRANULATION, DRYING AND TRIBOCHARGING BEHAVIOUR OF PHARMACEUTICAL POWDERS IN A FLUIDIZED BED DRYER

Wet granulation and drying are two crucial unit operations in the pharmaceutical industry. The two operations can be conducted in one piece of equipment, namely a fluidized bed. Fluidized beds have the advantages of excellent mixing, large contact area, and superior heat and mass transfer. Drying is typically operated at bubbling and turbulent regions. Despite the wide applications of fluidized beds in wet granulation and drying, there still remain challenges. Observation and measuring the dynamic granulation process are challenging with conventional experimental methods due to the opaque nature of pharmaceutical powders and the complex interaction between powders and liquid taking place in a short period of time. In this study, the dynamic granulation process was, for the first time, captured with synchrotron-based X-ray imaging techniques. The dynamic interaction between the pharmaceutical powders and the liquid binder was captured by high-resolution X-ray images. Results show that pharmaceutical powder properties, including particle size, hydrophilicity, and morphology, have significant influences on the dynamic granulation process and the final granular product. After wet granulation, the presence of high moisture content within pharmaceutical granules results in considerable cohesiveness. Agglomeration, channeling, defluidization, caused by the strong inter-particle forces, pose significant challenges to fluidization and drying, particularly at the beginning of the drying process. In this work, the drying performance of pharmaceutical granules was investigated in a pulsation-assisted fluidized bed dryer. It was found that pulsed airflow is effective in eliminating channeling and enhancing the drying rate at higher superficial gas velocity. Lower pulsation frequency is more favoured to improve the drying rate. Two typical drying stages were observed during the drying process, the constant rate period and the falling rate period. During the constant rate period, energy efficiency is between 60% to 45% for the drying process. The energy efficiency falls to 10% during the falling rate period. Nine thin-layer drying models were examined to predict the drying curve of the pharmaceutical granules. It was found that the Midilli and Kucuk model provided the best agreement between the experimental results and the predicted values. The pharmaceutical granules can be easily charged because of repeated collision and separation between particles and between particles and wall. The tribocharging behaviour of the pharmaceutical granules in a conventional FBD and a PFBD was investigated by varying operating conditions such as superficial gas velocity, inlet air temperature, pulsation frequency, and pulsed air ratio. It was found that the specific charge of the pharmaceutical granules remained lower than 0.2 µC/kg during the constant rate period. When the moisture content was reduced to a critical moisture content, namely 10%, the specific charge increased sharply regardless of the superficial gas velocity and inlet air temperature. Then, the increase in the specific charge continued before it reached an equilibrium value during the falling rate period. The equilibrium specific charge is influenced by the superficial gas velocity and pulsation frequency. Higher superficial gas velocity and lower pulsed frequency resulted in a higher specific charge. When the superficial gas velocity is low, there is no noticeable difference between the conventional FBD and the PFBD at different pulsation frequencies. The inlet air temperature and pulsed air ratio did not show an impact on the equilibrium specific charge value

Low cost fencing material for a pre-school in Lavender Hill

This project has been proposed by the UCT Knowledge Partnership Project. This institution is aimed at providing assistance to under-privileged communities in the Western Cape. A pre-school fence material which is low cost is to be investigated. The following criterions were set to be met for the material: -The material is to have no fuel usage value such as wood, which can be burnt for space heating -The material is to have no scrap metal value such as steel and wire fencing material as this easily gets stolen. -The material is not to block visibility which harbors criminal activity in the area. Fences such as concrete slabs and brick block visibility. The materials considered in this project are: -Various plastic polymer materials -Plastic Lumber composite material -Recycled Plastic -Rubber reinforced concrete Plastic lumber and recycled plastic HDPE were considered for use in the fence material. After considering the available fence components and loading on the fence, 100 x 100 mm cross section plastic lumber and recycled plastic section were chosen to be used. The fence design was based on existing patents which were modified. A design showing the meter of the fence was designed and is shown in the document

Spacecraft systems analysis project

The research in spacecraft analysis is reported. The Skylab task is reviewed along with the ASTP, and the shuttle tasks. The current status, progress, problems, and the work to be performed are described