title: Design and analysis of an efficient distributed event notification service

authors: Bittner, Sven

subjects: computer science

abstract: Event Notification Services (ENS) use the publish/subscribe paradigm to continuously inform subscribers about events they are interested in. Subscribers define their interest in so-called profiles. The event information is provided by event publishers, filtered by the service against the profiles, and then send to the subscribers. In real-time systems such as facility management, an efficiency filter component is one of the most important design goals.
In this paper, we present our analysis and evaluation of efficient distributed filtering algorithms. Firstly, we propose a classification and first-cut analysis of distributed filtering algorithms. Secondly, based on the classification we describe our analysis of selected algorithms. Thirdly, we describe our ENS prototype DAS that includes three filtering algorithms. This prototype is tested with respect to efficiency, network traffic and memory consumption. In this paper, we discuss the results of our practical analysis in detail.

text: Design and analysis of an efficient distributed event notification service Event Notification Services (ENS) use the publish/subscribe paradigm to continuously inform subscribers about events they are interested in. Subscribers define their interest in so-called profiles. The event information is provided by event publishers, filtered by the service against the profiles, and then send to the subscribers. In real-time systems such as facility management, an efficiency filter component is one of the most important design goals.
In this paper, we present our analysis and evaluation of efficient distributed filtering algorithms. Firstly, we propose a classification and first-cut analysis of distributed filtering algorithms. Secondly, based on the classification we describe our analysis of selected algorithms. Thirdly, we describe our ENS prototype DAS that includes three filtering algorithms. This prototype is tested with respect to efficiency, network traffic and memory consumption. In this paper, we discuss the results of our practical analysis in detail.

year: 2004-01-01

title: Open-Source tools for practical heat integration and utility system evaluation

authors: Hall, Keegan

abstract: Industrial energy use is one of the most significant contributors to global greenhouse gas emissions. One of the most effective strategies for reducing heat demand is optimising the design of heat exchanger networks (HENs). While automated synthesis methods like mathematical programming have long promised optimal designs, their industrial adoption remains limited. Key barriers include expensive software licenses, complexity of models and a disconnect between proposed thermal savings and real-world cost savings, especially for non-continuous processes. This thesis addresses these challenges by developing two complementary open-source tools that bridge the gap between advanced process integration methods and practical industrial implementation.
The novel contributions in this thesis are delivered across two primary streams: (1) the development of OpenHENS, an entirely open-source tool for synthesising cost-optimal HENs using a robust multi-stage solution strategy, and (2) a machine learning-based surrogate modelling approach for predicting utility system performance under new heat recovery or plant configurations. Together these contributions allow engineers to investigate multiple heat recovery options and accurately evaluate the operational cost savings. 
OpenHENS combines a novel three step strategy to systematically reduce model complexity and generate a broad set of structurally diverse near-optimal heat HENs. Engineers then apply their judgement in selecting a design that aligns with real-world constraints such as spatial layout, capital budgets, and controllability, factors often too complex to model directly. OpenHENS is publicly available as a Python-based open-source tool and is designed to be accessible to engineers without prior experience in mathematical programming or coding. When validated on thirteen common benchmark problems, OpenHENS consistently returned solutions within 8% of the lowest known total annualised costs reported in the literature using commercial optimisation software.
To support credible evaluation of energy efficiency projects, this thesis also develops a surrogate modelling framework tailored for large, non-continuous industrial sites where utility system behaviour is influenced by variable production, operator decisions, and equipment constraints. Trained on high-resolution plant data, the model captures non-linear, time-dependent system behaviour and is used to predict fuel consumption, cogeneration, boiler steam generation, and equipment-level steam demand across full-year operational periods. The approach is demonstrated through the evaluation of a hot water network retrofit at a pulp and paper mill, where standard costing methods were found to overestimate annual savings by NZD $9.8 million. The surrogate model also enables fair cost allocation prior to the design phases by quantifying the marginal steam cost (MSC) at each plant. Results showed that the hot water network retrofit had a MSC of -$10 per tonne, whereas the pulp dryer and paper machine had the highest MSCs around $20 per tonne.
Beyond HEN evaluation, the surrogate model supports strategic scenario analysis for energy decision-making. The model was used to assess the implications of shutting down paper production on steam balances, asset utilisation, and site-wide fuel costs. The results revealed unintended consequences, including increased natural gas usage and instability due to low boiler turndown. Because the model reflects actual operational patterns embedded in historical data, these insights underscore the need for improved utility system operation. Additional ‘what-if’ scenarios demonstrated the potential for significant cost reductions by integrating new power generation technologies that recover surplus steam from biomass combustion.

text: Open-Source tools for practical heat integration and utility system evaluation Industrial energy use is one of the most significant contributors to global greenhouse gas emissions. One of the most effective strategies for reducing heat demand is optimising the design of heat exchanger networks (HENs). While automated synthesis methods like mathematical programming have long promised optimal designs, their industrial adoption remains limited. Key barriers include expensive software licenses, complexity of models and a disconnect between proposed thermal savings and real-world cost savings, especially for non-continuous processes. This thesis addresses these challenges by developing two complementary open-source tools that bridge the gap between advanced process integration methods and practical industrial implementation.
The novel contributions in this thesis are delivered across two primary streams: (1) the development of OpenHENS, an entirely open-source tool for synthesising cost-optimal HENs using a robust multi-stage solution strategy, and (2) a machine learning-based surrogate modelling approach for predicting utility system performance under new heat recovery or plant configurations. Together these contributions allow engineers to investigate multiple heat recovery options and accurately evaluate the operational cost savings. 
OpenHENS combines a novel three step strategy to systematically reduce model complexity and generate a broad set of structurally diverse near-optimal heat HENs. Engineers then apply their judgement in selecting a design that aligns with real-world constraints such as spatial layout, capital budgets, and controllability, factors often too complex to model directly. OpenHENS is publicly available as a Python-based open-source tool and is designed to be accessible to engineers without prior experience in mathematical programming or coding. When validated on thirteen common benchmark problems, OpenHENS consistently returned solutions within 8% of the lowest known total annualised costs reported in the literature using commercial optimisation software.
To support credible evaluation of energy efficiency projects, this thesis also develops a surrogate modelling framework tailored for large, non-continuous industrial sites where utility system behaviour is influenced by variable production, operator decisions, and equipment constraints. Trained on high-resolution plant data, the model captures non-linear, time-dependent system behaviour and is used to predict fuel consumption, cogeneration, boiler steam generation, and equipment-level steam demand across full-year operational periods. The approach is demonstrated through the evaluation of a hot water network retrofit at a pulp and paper mill, where standard costing methods were found to overestimate annual savings by NZD $9.8 million. The surrogate model also enables fair cost allocation prior to the design phases by quantifying the marginal steam cost (MSC) at each plant. Results showed that the hot water network retrofit had a MSC of -$10 per tonne, whereas the pulp dryer and paper machine had the highest MSCs around $20 per tonne.
Beyond HEN evaluation, the surrogate model supports strategic scenario analysis for energy decision-making. The model was used to assess the implications of shutting down paper production on steam balances, asset utilisation, and site-wide fuel costs. The results revealed unintended consequences, including increased natural gas usage and instability due to low boiler turndown. Because the model reflects actual operational patterns embedded in historical data, these insights underscore the need for improved utility system operation. Additional ‘what-if’ scenarios demonstrated the potential for significant cost reductions by integrating new power generation technologies that recover surplus steam from biomass combustion.

year: 2025

title: Kia rehe te matau, kia rehe te maui

authors: Winiata, Te Whatanui Huia

subjects: Taiaha, Maori business, maori development

abstract: The theory of applying successful military strategy to the world of business is not a new concept.  The connection between these two environments has often been explored, and works by Sun Tzu and others promote the connection between the battlefield and the boardroom.  The cut and thrust of the business realm is often likened to combat, and the guiding principles and beliefs that influence Generals and Field Commanders are in many ways identical to those of executives and Chief Executive Officers.

This thesis is interested in exploring the interconnectedness between battle and business from a Māori perspective.  In particular, this study explores the link between the Māori weapon known as the taiaha, and Māori business, in the belief that the lessons learnt from the various taiaha schools can be transferred to Māori business.  Likewise, the beliefs, principles and philosophies that are instilled within warriors while training with the taiaha have a valid place within Māori business, and when applied to the Māori business arena, have beneficial outcomes for those involved.

This study highlights fundamental taiaha principles that are applicable to the Māori business world.  These beliefs have been identified by a number of taiaha experts as well as successful Māori business operators.  The long term purpose of this thesis is to support Māori entering into business, by highlighting traditional values that are taught through the medium of taiaha, and showing how they can be applied to business.

text: Kia rehe te matau, kia rehe te maui The theory of applying successful military strategy to the world of business is not a new concept.  The connection between these two environments has often been explored, and works by Sun Tzu and others promote the connection between the battlefield and the boardroom.  The cut and thrust of the business realm is often likened to combat, and the guiding principles and beliefs that influence Generals and Field Commanders are in many ways identical to those of executives and Chief Executive Officers.

This thesis is interested in exploring the interconnectedness between battle and business from a Māori perspective.  In particular, this study explores the link between the Māori weapon known as the taiaha, and Māori business, in the belief that the lessons learnt from the various taiaha schools can be transferred to Māori business.  Likewise, the beliefs, principles and philosophies that are instilled within warriors while training with the taiaha have a valid place within Māori business, and when applied to the Māori business arena, have beneficial outcomes for those involved.

This study highlights fundamental taiaha principles that are applicable to the Māori business world.  These beliefs have been identified by a number of taiaha experts as well as successful Māori business operators.  The long term purpose of this thesis is to support Māori entering into business, by highlighting traditional values that are taught through the medium of taiaha, and showing how they can be applied to business.

year: 2013