Investigation of chaotic mixing in laminar fluid systems by the use of computational fluid dynamics

This work presents significant development into chaotic mixing induced through periodic boundaries and twisting flows. Three-dimensional closed and throughput domains are shown to exhibit chaotic motion under both time periodic and time independent boundary motions, A property is developed originating from a signature of chaos, sensitive dependence to initial conditions, which successfully quantifies the degree of disorder withjn the mixing systems presented and enables comparisons of the disorder throughout ranges of operating parameters, This work omits physical experimental results but presents significant computational investigation into chaotic systems using commercial computational fluid dynamics techniques. Physical experiments with chaotic mixing systems are, by their very nature, difficult to extract information beyond the recognition that disorder does, does not of partially occurs. The initial aim of this work is to observe whether it is possible to accurately simulate previously published physical experimental results through using commercial CFD techniques. This is shown to be possible for simple two-dimensional systems with time periodic wall movements. From this, and subsequent macro and microscopic observations of flow regimes, a simple explanation is developed for how boundary operating parameters affect the system disorder. Consider the classic two-dimensional rectangular cavity with time periodic velocity of the upper and lower walls, causing two opposing streamline motions. The degree of disorder within the system is related to the magnitude of displacement of individual particles within these opposing streamlines. The rationale is then employed in this work to develop and investigate more complex three-dimensional mixing systems that exhibit throughputs and time independence and are therefore more realistic and a significant advance towards designing chaotic mixers for process industries. Domains inducing chaotic motion through twisting flows are also briefly considered. This work concludes by offering possible advancements to the property developed to quantify disorder and suggestions of domains and associated boundary conditions that are expected to produce chaotic mixing.

Nations and organizations:a comparative study of English and Indian work-related attitudes and values in matched manufacturing firms

This thesis reports a cross-national study carried out in England and India in an attempt to clarify the association of certain cultural and non-cultural characteristics with people's work-related attitudes and values, and with the structure of their work organizations. Three perspectives are considered to be relevant to the objectives of the study. The contingency perspective suggests that a 'fit' between an organization's context and its structural arrangements will be fundamentally necessary for achieving success and survival. The political economy perspective argues for the determining role of the social and economic structures within which the organization operates. The culturalist perspective looks to cultural attitudes and values of organizational members for an explanation for their organization's structure. The empirical investigation was carried out in three stages in each of the two countries involved by means of surveys of cultural attitudes, work-related attitudes and organizational structures and systems. The cultural surveys suggested that Indian and English people were different from one another with regard to fear of, and respect and obedience to, their seniors, ability to cope with ambiguity, honesty, independence, expression of emotions, fatalism, reserve, and care for others; they were similar with regard to tolerance, friendliness, attitude to change, attitude to law, self-control and self-confidence, and attitude to social differentiation. The second stage of the study, involving the employees of fourteen organizations, found that the English ones perceived themselves to have more power at work, expressed more tolerance for ambiguity, and had different expectations from their job than did the Indian equivalents. The two samples were similar with respect to commitment to their company and trust in their colleagues. The findings also suggested that employees' occupations, education and age had some influences on their work-related attitudes. The final stage of the research was a study of structures, control systems, and reward and punishment policies of the same fourteen organizations which were matched almost completely on their contextual factors across the two countries. English and Indian organizations were found to be similar in terms of centralization, specialization, chief executive's span of control, height and management control strategies. English organizations, however, were far more formalized, spent more time on consultation and their managers delegated authority lower down the hierarchy than Indian organizations. The major finding of the study was the multiple association that cultural, national and contingency factors had with the structural characteristics of the organizations and with the work-related attitudes of their members. On the basis of this finding, a multi-perspective model for understanding organizational structures and systems is proposed in which the contributions made by contingency, political economy and cultural perspectives are recognized and incorporated.

Simulation and Evaluation of High-Voltage Power Systems for Civil Aircraft

A status report of the modelling and simulation work that is being undertaken as part of the TIMES (Totally Integrated More Electric Systems) project is presented. Dynamic power quality simulations have been used to asses the performance of the electrical system of a EMA based actuation system for an Airbus A330 size aircraft, for both low voltage 115 V, and high voltage 230 V three-phase AC systems. The high voltage system is shown to have benefits in terms of power quality and reduced size and weight of equipment.

Advances in characterisation, calibration and data processing speed of optical coherence tomography systems

This thesis describes advances in the characterisation, calibration and data processing of optical coherence tomography (OCT) systems. Femtosecond (fs) laser inscription was used for producing OCT-phantoms. Transparent materials are generally inert to infra-red radiations, but with fs lasers material modification occurs via non-linear processes when the highly focused light source interacts with the materials. This modification is confined to the focal volume and is highly reproducible. In order to select the best inscription parameters, combination of different inscription parameters were tested, using three fs laser systems, with different operating properties, on a variety of materials. This facilitated the understanding of the key characteristics of the produced structures with the aim of producing viable OCT-phantoms. Finally, OCT-phantoms were successfully designed and fabricated in fused silica. The use of these phantoms to characterise many properties (resolution, distortion, sensitivity decay, scan linearity) of an OCT system was demonstrated. Quantitative methods were developed to support the characterisation of an OCT system collecting images from phantoms and also to improve the quality of the OCT images. Characterisation methods include the measurement of the spatially variant resolution (point spread function (PSF) and modulation transfer function (MTF)), sensitivity and distortion. Processing of OCT data is a computer intensive process. Standard central processing unit (CPU) based processing might take several minutes to a few hours to process acquired data, thus data processing is a significant bottleneck. An alternative choice is to use expensive hardware-based processing such as field programmable gate arrays (FPGAs). However, recently graphics processing unit (GPU) based data processing methods have been developed to minimize this data processing and rendering time. These processing techniques include standard-processing methods which includes a set of algorithms to process the raw data (interference) obtained by the detector and generate A-scans. The work presented here describes accelerated data processing and post processing techniques for OCT systems. The GPU based processing developed, during the PhD, was later implemented into a custom built Fourier domain optical coherence tomography (FD-OCT) system. This system currently processes and renders data in real time. Processing throughput of this system is currently limited by the camera capture rate. OCTphantoms have been heavily used for the qualitative characterization and adjustment/ fine tuning of the operating conditions of OCT system. Currently, investigations are under way to characterize OCT systems using our phantoms. The work presented in this thesis demonstrate several novel techniques of fabricating OCT-phantoms and accelerating OCT data processing using GPUs. In the process of developing phantoms and quantitative methods, a thorough understanding and practical knowledge of OCT and fs laser processing systems was developed. This understanding leads to several novel pieces of research that are not only relevant to OCT but have broader importance. For example, extensive understanding of the properties of fs inscribed structures will be useful in other photonic application such as making of phase mask, wave guides and microfluidic channels. Acceleration of data processing with GPUs is also useful in other fields.

Logical Models of Composite Dynamic Objects Control

The questions of designing multicriteria control systems on the basis of logic models of composite dynamic objects are considered.

Timed Transition Automata as Numerical Planning Domain

A general technique for transforming a timed finite state automaton into an equivalent automated planning domain based on a numerical parameter model is introduced. Timed transition automata have many applications in control systems and agents models; they are used to describe sequential processes, where actions are labelling by automaton transitions subject to temporal constraints. The language of timed words accepted by a timed automaton, the possible sequences of system or agent behaviour, can be described in term of an appropriate planning domain encapsulating the timed actions patterns and constraints. The time words recognition problem is then posed as a planning problem where the goal is to reach a final state by a sequence of actions, which corresponds to the timed symbols labeling the automaton transitions. The transformation is proved to be correct and complete and it is space/time linear on the automaton size. Experimental results shows that the performance of the planning domain obtained by transformation is scalable for real world applications. A major advantage of the planning based approach, beside of the solving the parsing problem, is to represent in a single automated reasoning framework problems of plan recognitions, plan synthesis and plan optimisation.

A mixture density network approach to modelling and exploiting uncertainty in nonlinear control problems

In nonlinear and stochastic control problems, learning an efficient feed-forward controller is not amenable to conventional neurocontrol methods. For these approaches, estimating and then incorporating uncertainty in the controller and feed-forward models can produce more robust control results. Here, we introduce a novel inversion-based neurocontroller for solving control problems involving uncertain nonlinear systems which could also compensate for multi-valued systems. The approach uses recent developments in neural networks, especially in the context of modelling statistical distributions, which are applied to forward and inverse plant models. Provided that certain conditions are met, an estimate of the intrinsic uncertainty for the outputs of neural networks can be obtained using the statistical properties of networks. More generally, multicomponent distributions can be modelled by the mixture density network. Based on importance sampling from these distributions a novel robust inverse control approach is obtained. This importance sampling provides a structured and principled approach to constrain the complexity of the search space for the ideal control law. The developed methodology circumvents the dynamic programming problem by using the predicted neural network uncertainty to localise the possible control solutions to consider. A nonlinear multi-variable system with different delays between the input-output pairs is used to demonstrate the successful application of the developed control algorithm. The proposed method is suitable for redundant control systems and allows us to model strongly non-Gaussian distributions of control signal as well as processes with hysteresis. © 2004 Elsevier Ltd. All rights reserved.

High-Order Control Variations and Small-Time Local Controllability

The importance of “control variations” for obtaining local approximations of the reachable set of nonlinear control systems is well known. Heuristically, if one can construct control variations in all possible directions, then the considered control system is small-time locally controllable (STLC). Two concepts of control variations of higher order are introduced for the case of smooth control systems. The relation between these variations and the small-time local controllability is studied and a new sufficient STLC condition is proved.

Understanding the dynamics of information technology implementation: The case of clinical information systems

The ultimate intent of this dissertation was to broaden and strengthen our understanding of IT implementation by emphasizing research efforts on the dynamic nature of the implementation process. More specifically, efforts were directed toward opening the "black box" and providing the story that explains how and why contextual conditions and implementation tactics interact to produce project outcomes. In pursuit of this objective, the dissertation was aimed at theory building and adopted a case study methodology combining qualitative and quantitative evidence. Precisely, it examined the implementation process, use and consequences of three clinical information systems at Jackson Memorial Hospital, a large tertiary care teaching hospital.^ As a preliminary step toward the development of a more realistic model of system implementation, the study proposes a new set of research propositions reflecting the dynamic nature of the implementation process.^ Findings clearly reveal that successful implementation projects are likely to be those where key actors envision end goals, anticipate challenges ahead, and recognize the presence of and seize opportunities. It was also found that IT implementation is characterized by the systems theory of equifinality, that is, there are likely several equally effective ways to achieve a given end goal. The selection of a particular implementation strategy appears to be a rational process where actions and decisions are largely influenced by the degree to which key actors recognize the mediating role of each tactic and are motivated to action. The nature of the implementation process is also characterized by the concept of "duality of structure," that is, context and actions mutually influence each other. Another key finding suggests that there is no underlying program that regulates the process of change and moves it form one given point toward a subsequent and already prefigured end. For this reason, the implementation process cannot be thought of as a series of activities performed in a sequential manner such as conceived in stage models. Finally, it was found that IT implementation is punctuated by a certain indeterminacy. Results suggest that only when substantial efforts are focused on what to look for and think about, it is less likely that unfavorable and undesirable consequences will occur. ^

Optimization of adaptive traffic signal control with transit signal priority at isolated intersections using parallel genetic algorithms

Optimization of adaptive traffic signal timing is one of the most complex problems in traffic control systems. This dissertation presents a new method that applies the parallel genetic algorithm (PGA) to optimize adaptive traffic signal control in the presence of transit signal priority (TSP). The method can optimize the phase plan, cycle length, and green splits at isolated intersections with consideration for the performance of both the transit and the general vehicles. Unlike the simple genetic algorithm (GA), PGA can provide better and faster solutions needed for real-time optimization of adaptive traffic signal control. ^ An important component in the proposed method involves the development of a microscopic delay estimation model that was designed specifically to optimize adaptive traffic signal with TSP. Macroscopic delay models such as the Highway Capacity Manual (HCM) delay model are unable to accurately consider the effect of phase combination and phase sequence in delay calculations. In addition, because the number of phases and the phase sequence of adaptive traffic signal may vary from cycle to cycle, the phase splits cannot be optimized when the phase sequence is also a decision variable. A "flex-phase" concept was introduced in the proposed microscopic delay estimation model to overcome these limitations. ^ The performance of PGA was first evaluated against the simple GA. The results show that PGA achieved both faster convergence and lower delay for both under- or over-saturated traffic conditions. A VISSIM simulation testbed was then developed to evaluate the performance of the proposed PGA-based adaptive traffic signal control with TSP. The simulation results show that the PGA-based optimizer for adaptive TSP outperformed the fully actuated NEMA control in all test cases. The results also show that the PGA-based optimizer was able to produce TSP timing plans that benefit the transit vehicles while minimizing the impact of TSP on the general vehicles. The VISSIM testbed developed in this research provides a powerful tool to design and evaluate different TSP strategies under both actuated and adaptive signal control. ^

Welke 'acteur' neemt de controllerrol als extraverte business partner?

Which 'actor' takes the management accountant role as an extravert business partner? Does a relation between the personal trait Extraversion and fulfilling a management accountant role as a business partner exist? Open Universiteit Nederland End thesis MSc Management, Accounting & Finance Support 1: Prof. dr. A.C.N. van de Ven RA Support 2: dr. P.C.M. Claes Examinator: dr. P. Kamminga Date of approval: September 3, 2014 student: P.R. van der Wal (studentnumber 839104017 email petervanderwal2003@yahoo.com The main question of this research is: Does a relation between the personal trait Extraversion and fulfilling a management accountant role as a business partner exist? This research is based on the dataset obtained by the controller survey 2013, executed in commission of the 'Open Universiteit' (Bork & van der Wal, 2014). From the literature review it is clear: among other management accountant roles we need business partners. And there is a relation between the personal trait Extraversion and fulfilling the role as business partner. At the same time a lack of necessary personal traits for this role has been noticed, among which is Extraversion. The factor- and cluster analyses reported by Bork & van der Wal (2014) resulted in the identification of two types of management accountant roles. In this extended research TYPE II is identified as a business partner because (s)he practices activity-combinations which are related to strategy, analyzing, supporting management in decision making, advisory, change-agency and representing the organization. 36% of the population of Dutch management accountants with a master degree (or similar) meet with the role of the business partner. Although the fulfillment of the role (TYPE II) is not purely business partnering. E.g. reporting and scorekeeping are still activities executed by TYPE II and it is not clear to what extent. Apart from that, role TYPE I executes change management and risk-management activities, which are (according to the definition) activities that belong to the business partner. The role as business partner is practiced but not that optimal as defined in theory. The logistic regression analyses on the survey-data show that Extraversion among three other triggers is significant for the prediction of the fulfillment of the management accountant role (Bork & van der Wal, 2014). A more extravert personal trait predicts a preference for TYPE II, which relates to the business partner. This 'in depth research' concentrated on the relation between the Big Five personal traits and the six activity-combinations (factors) instead of on the two clusters (I and II). The statistic analyses confirm the predicting influence of Extraversion on the business partner role. Although, except for one factor, no extra significance has been found in this additional research. The essential question can be confirmed positively: the management accountant role business partner exists in practice, some management accountants are more extravert then others, and there is a positive relation between extraversion and fulfilling the business partner role. Some formulated research limitations are related to the statistical weakness of some prediction outcomes and to interpretation differences that might occur. Further research can e.g. concentrate on the other personal traits and the significance for role-differentiation in education programs. The management accountant survey 2013 Management accountant roles in 2013 in the Netherlands Open Universiteit Nederland End thesis MSc Management, Accounting & Finance Support 1: Prof. dr. A.C.N. van de Ven RA Support 2: dr. P.C.M. Claes Examinator: dr. P. Kamminga Date of approval: September 3, 2014 student: P.R. van der Wal and H.J. Bork studentnumber: 839104017 and 838532340) email: petervanderwal2003@yahoo.com and hjbork@hotmail.com This paper describes the conceptual model and results of the 'management accountants survey 2013'. The survey is part of a longitudinal survey, earlier executed in 2004, 2007 and 2010 under responsibility of the 'Open Universiteit Nederland'. Secondly the dataset of this survey will be used by us to do our own analyses on the predicting value of the triggers 'personality factor: extraversion' and 'lever of control: interactive controls' on the management accounting role that comes close to a role defined as 'Business Partner'. Scientific research shows that there are different management accounting roles, and that these roles change and that preferences exist for certain roles (Verstegen B. , Loo, Mol, Slagter, & Geerkens, 2007). The main question that will be answered in this paper is which coherent combinations of activities are being executed by management accountants in 2013 in the Netherlands by master-graduates? And secondly which triggers of management accountants' activities predict to which cluster a management accountant belongs? The conceptual model of this research has been developed in 2004 (Verstegen B. , Loo, Mol, Slagter, & Geerkens, 2007). For this research the same 37 activities as in the former researches are included (appendix 1). In the trigger-set (appendix 1) some adaptations have been made for reasons of restricting the length of the survey and to pinpoint on particular research goals (e.g. personality and levers of control). The coherent combinations of activities were found by a factor-analysis and the groups of controllers by a cluster analysis. A regression analysis shows which trigger-items are most significant. The survey has been sent to 2.353 students that finished a controller-study on a Dutch University. There was a 9% (211) response with a completely filled survey. 137 of which indicated to work in a controller-function at the moment. These controllers have been included in the results. The factor-analysis results in six different coherent combinations of activities (factors). Shortly these factors are: advising top management on strategic level with result-effecting information (1), organizing internal reporting (2) organizing and representing the organization on external reporting (3), advising and managing changes by shortcomings in processes and control systems (4), maintaining and managing administrative organization- , information- and control systems (5) and organizing/executing risk management and internal audit (6). Factors 4, 5 and 6 are clustered in cluster TYPE I (125 controllers) and factors 1, 2 and 3 in cluster TYPE II (69 controllers). TYPE II can be associated with the management accountant role 'Business Partner', although the accountant keeps partly active in a scorekeeper role. The four most significant triggers for predicting being a TYPE II controller are 'Executing a risk-management task in order to meet compliance standards' (1), extraversion (2), company size in terms of fte (3) and gender (4).

Threat Analysis of BlackEnergy Malware for Synchrophasor based Real-time Control and Monitoring in Smart Grid

The BlackEnergy malware targeting critical infrastructures has a long history. It evolved over time from a simple DDoS platform to a quite sophisticated plug-in based malware. The plug-in architecture has a persistent malware core with easily installable attack specific modules for DDoS, spamming, info-stealing, remote access, boot-sector formatting etc. BlackEnergy has been involved in several high profile cyber physical attacks including the recent Ukraine power grid attack in December 2015. This paper investigates the evolution of BlackEnergy and its cyber attack capabilities. It presents a basic cyber attack model used by BlackEnergy for targeting industrial control systems. In particular, the paper analyzes cyber threats of BlackEnergy for synchrophasor based systems which are used for real-time control and monitoring functionalities in smart grid. Several BlackEnergy based attack scenarios have been investigated by exploiting the vulnerabilities in two widely used synchrophasor communication standards: (i) IEEE C37.118 and (ii) IEC 61850-90-5. Specifically, the paper addresses reconnaissance, DDoS, man-in-the-middle and replay/reflection attacks on IEEE C37.118 and IEC 61850-90-5. Further, the paper also investigates protection strategies for detection and prevention of BlackEnergy based cyber physical attacks.

Integrated Optimal Power Flow for Distribution Networks in Local and Urban Scales

This paper develops an integrated optimal power flow (OPF) tool for distribution networks in two spatial scales. In the local scale, the distribution network, the natural gas network, and the heat system are coordinated as a microgrid. In the urban scale, the impact of natural gas network is considered as constraints for the distribution network operation. The proposed approach incorporates unbalance three-phase electrical systems, natural gas systems, and combined cooling, heating, and power systems. The interactions among the above three energy systems are described by energy hub model combined with components capacity constraints. In order to efficiently accommodate the nonlinear constraint optimization problem, particle swarm optimization algorithm is employed to set the control variables in the OPF problem. Numerical studies indicate that by using the OPF method, the distribution network can be economically operated. Also, the tie-line power can be effectively managed.

Calibrated Polarisation Tilt Angle Recovery for Wireless Communications

In this paper, we show how the polarisation state of a linearly polarised antenna can be recovered through the use of a three-term error correction model. The approach adopted is shown to be robust in situations where some multipath exists and where the sampling channels are imperfect with regard to both their amplitude and phase tracking. In particular, it has been shown that error of the measured polarisation tilt angle can be improved from 33% to 3% and below by applying the proposed calibration method. It is described how one can use a rotating dipole antenna as both the calibration standard and as the polarisation encoder, thus simplifying the physical arrangement of the transmitter. Experimental results are provided in order to show the utility of the approach, which could have a variety of applications including bandwidth conservative polarisation sub-modulation in advanced wireless communications systems.

Residence Time Distribution (Rtd) Associated with Statistical Weighted Moments to Fit Mathematical Models Using In Industrial Systems Diagnosis

This work presents a computational, called MOMENTS, code developed to be used in process control to determine a characteristic transfer function to industrial units when radiotracer techniques were been applied to study the unit´s performance. The methodology is based on the measuring the residence time distribution function (RTD) and calculate the first and second temporal moments of the tracer data obtained by two scintillators detectors NaI positioned to register a complete tracer movement inside the unit. Non linear regression technique has been used to fit various mathematical models and a statistical test was used to select the best result to the transfer function. Using the code MOMENTS, twelve different models can be used to fit a curve and calculate technical parameters to the unit.