A Modular Software Framework for Compression of Structured Climate Data

Through the introduction of next-generation models the climate sciences have experienced a breakthrough in high-resolution simulations. In the past, the bottleneck was the numerical complexity of the models, nowadays it is the required storage space for the model output. One way to tackle the data storage challenge is through data compression. In this article we introduce a modular framework for the compression of structured climate data. Our modular framework supports the creation of individual predictors, which can be customised and adjusted to the data at hand. We provide a framework for creating interfaces and customising components, which are building blocks of individualised compression modules that are optimised for particular applications. Furthermore, the framework provides additional features such as the execution of benchmarks and validity tests for sequential as well as parallel execution of compression algorithms

Compression Methods for Structured Floating-Point Data and their Application in Climate Research

The use of new technologies, such as GPU boosters, have led to a dramatic increase in the computing power of High-Performance Computing (HPC) centres. This development, coupled with new climate models that can better utilise this computing power thanks to software development and internal design, led to the bottleneck moving from solving the differential equations describing Earth’s atmospheric interactions to actually storing the variables. The current approach to solving the storage problem is inadequate: either the number of variables to be stored is limited or the temporal resolution of the output is reduced. If it is subsequently determined that another vari- able is required which has not been saved, the simulation must run again. This thesis deals with the development of novel compression algorithms for structured floating-point data such as climate data so that they can be stored in full resolution. Compression is performed by decorrelation and subsequent coding of the data. The decorrelation step eliminates redundant information in the data. During coding, the actual compression takes place and the data is written to disk. A lossy compression algorithm additionally has an approx- imation step to unify the data for better coding. The approximation step reduces the complexity of the data for the subsequent coding, e.g. by using quantification. This work makes a new scientific contribution to each of the three steps described above. This thesis presents a novel lossy compression method for time-series data using an Auto Regressive Integrated Moving Average (ARIMA) model to decorrelate the data. In addition, the concept of information spaces and contexts is presented to use information across dimensions for decorrela- tion. Furthermore, a new coding scheme is described which reduces the weaknesses of the eXclusive-OR (XOR) difference calculation and achieves a better compression factor than current lossless compression methods for floating-point numbers. Finally, a modular framework is introduced that allows the creation of user-defined compression algorithms. The experiments presented in this thesis show that it is possible to in- crease the information content of lossily compressed time-series data by applying an adaptive compression technique which preserves selected data with higher precision. An analysis for lossless compression of these time- series has shown no success. However, the lossy ARIMA compression model proposed here is able to capture all relevant information. The reconstructed data can reproduce the time-series to such an extent that statistically rele- vant information for the description of climate dynamics is preserved. Experiments indicate that there is a significant dependence of the com- pression factor on the selected traversal sequence and the underlying data model. The influence of these structural dependencies on prediction-based compression methods is investigated in this thesis. For this purpose, the concept of Information Spaces (IS) is introduced. IS contributes to improv- ing the predictions of the individual predictors by nearly 10% on average. Perhaps more importantly, the standard deviation of compression results is on average 20% lower. Using IS provides better predictions and consistent compression results. Furthermore, it is shown that shifting the prediction and true value leads to a better compression factor with minimal additional computational costs. This allows the use of more resource-efficient prediction algorithms to achieve the same or better compression factor or higher throughput during compression or decompression. The coding scheme proposed here achieves a better compression factor than current state-of-the-art methods. Finally, this paper presents a modular framework for the development of compression algorithms. The framework supports the creation of user- defined predictors and offers functionalities such as the execution of bench- marks, the random subdivision of n-dimensional data, the quality evalua- tion of predictors, the creation of ensemble predictors and the execution of validity tests for sequential and parallel compression algorithms. This research was initiated because of the needs of climate science, but the application of its contributions is not limited to it. The results of this the- sis are of major benefit to develop and improve any compression algorithm for structured floating-point data

Living Knowledge

Diversity, especially manifested in language and knowledge, is a function of local goals, needs, competences, beliefs, culture, opinions and personal experience. The Living Knowledge project considers diversity as an asset rather than a problem. With the project, foundational ideas emerged from the synergic contribution of different disciplines, methodologies (with which many partners were previously unfamiliar) and technologies flowed in concrete diversity-aware applications such as the Future Predictor and the Media Content Analyser providing users with better structured information while coping with Web scale complexities. The key notions of diversity, fact, opinion and bias have been defined in relation to three methodologies: Media Content Analysis (MCA) which operates from a social sciences perspective; Multimodal Genre Analysis (MGA) which operates from a semiotic perspective and Facet Analysis (FA) which operates from a knowledge representation and organization perspective. A conceptual architecture that pulls all of them together has become the core of the tools for automatic extraction and the way they interact. In particular, the conceptual architecture has been implemented with the Media Content Analyser application. The scientific and technological results obtained are described in the following

PACS for the Developing World

Digital imaging is now firmly ensconced in the developed world. Its widespread adoption has enabled instant access to images, remote viewing, remote consultation, and the end of lost or misplaced film. Unfortunately, the current paradigm of Picture Archiving and Communication System (PACS), with advanced technology inseparable from high complexity, high purchase costs, and high maintenance costs, is not suited for the low-income developing world. Like the simple, easy to repair, 1950’s American cars still running on the streets of Havana, the developing world requires a PACS (DW-PACS) that can perform basic functions and survive in a limited-resource environment. The purpose of this article is to more fully describe this concept and to present a blueprint for PACS tailored to the needs and resources of the developing world. This framework should assist both users looking for a vendor-supplied or open-source solutions and developers seeking to address the needs of this emerging market

AIMES: advanced computation and I/O methods for earth-system simulations

Dealing with extreme scale Earth-system models is challenging from the computer science perspective, as the required computing power and storage capacity are steadily increasing. Scientists perform runs with growing resolution or aggregate results from many similar smaller-scale runs with slightly different initial conditions (the so-called ensemble runs). In the fifth Coupled Model Intercomparison Project (CMIP5), the produced datasets require more than three Petabytes of storage and the compute and storage requirements are increasing significantly for CMIP6. Climate scientists across the globe are developing next-generation models based on improved numerical formulation leading to grids that are discretized in alternative forms such as an icosahedral (geodesic) grid. The developers of these models face similar problems in scaling, maintaining and optimizing code. Performance portability and the maintainability of code are key concerns of scientists as, compared to industry projects, model code is continuously revised and extended to incorporate further levels of detail. This leads to a rapidly growing code base that is rarely refactored. However, code modernization is important to maintain productivity of the scientist working with the code and for utilizing performance provided by modern and future architectures. The need for performance optimization is motivated by the evolution of the parallel architecture landscape from homogeneous flat machines to heterogeneous combinations of processors with deep memory hierarchy. Notably, the rise of many-core, throughput-oriented accelerators, such as GPUs, requires non-trivial code changes at minimum and, even worse, may necessitate a substantial rewrite of the existing codebase. At the same time, the code complexity increases the difficulty for computer scientists and vendors to understand and optimize the code for a given system. Storing the products of climate predictions requires a large storage and archival system which is expensive. Often, scientists restrict the number of scientific variables and write interval to keep the costs balanced. Compression algorithms can reduce the costs significantly but can also increase the scientific yield of simulation runs. In the AIMES project, we addressed the key issues of programmability, computational efficiency and I/O limitations that are common in next-generation icosahedral earth-system models. The project focused on the separation of concerns between domain scientist, computational scientists, and computer scientists

Innovation in China: Fragmentation, Structured Uncertainty, and Technology Standards

This Article discusses the history of China’s attempts to develop indigenous technology standards. A case study is presented on China’s attempts to develop digital optical storage media standards, the failure of which we attribute to fragmentation of production and structured uncertainty in China’s economy. Despite the market failures of China’s domestic standards development efforts, we conclude by highlighting some of the appurtenant benefits they produce for Chinese manufacturers

COOLFACADE

The thesis ‘COOLFACADE – Architectural integration of solar cooling strategies in the building envelope’ aims to shed light on the possibilities and constraints for architectural integration of solar cooling systems in façades, in order to support the design of climate responsive architectural products for office buildings as self-sufficient alternatives to conventional air-conditioning systems. Increasing cooling needs in the built environment present an important and complex challenge for the design of sustainable buildings and cities. Even though the first course of action should always aim to reduce energy consumption through saving measures and passive design, this is often not enough to avoid mechanical equipment altogether, particularly in the case of office buildings in warm climate contexts. Solar cooling technologies have been increasingly explored, as an environmentally friendly alternative to harmful refrigerants used within vapour compression systems; while also being driven by solar, thus, renewable energy. The principles behind some of these technologies have been researched for over a century, reaching mature solutions and components, and being recognised as promising alternatives to common  air-conditioning units. Nonetheless, building application remains mostly limited to demonstration projects and pilot experiences. Recently, façade integrated concepts have been explored, as a way to promote widespread application throughout the development of multifunctional building components. However, while these are regarded as relevant and promising standalone concepts, further research is still needed to assess the integration potential of diverse solar cooling technologies, and identify barriers to overcome, in order to promote the widespread application of solar cooling components in the built environment. The aim of this research project is to explore the possibilities and constraints for architectural integration of solar cooling strategies in façades, in order to support the design of climate responsive architectural products for office buildings, without compromising the thermal comfort of users. The underlying hypothesis then is that self-sufficient solar cooling integrated facades may be a promising alternative to conventional centralised air-conditioning systems widely used in office buildings in warm climates. Most research efforts on solar cooling currently deal with the optimisation of the systems in terms of their performance, testing new materials and simplifying their operation to increase reported efficiencies. However, there is a lack of knowledge on the requirements and current limits for widespread façade application. In order to achieve the research goal and comprehensively assess the façade integration potential of solar technologies and discuss current barriers, different aspects must be acknowledged. These distinct aspects are addressed through several research questions, which in turn define the different chapters of the dissertation. Introduction and conclusions aside, the research body is structured on three sequential parts, with 2-3 chapters each. The first part deals with the state-of-the-art in the field and the theoretical framework, laying the groundwork for the following sections. The second part explores different aspects required as input for façade integration; while the third part comprises the evaluation of solar cooling technologies in terms of current possibilities and constraints for the development of integrated façades, based on the inputs identified in the second part. Furthermore, all chapters were published or submitted for publication as scientific articles in peer review academic journals. The first part considers two chapters that lay the foundations for the research project, The first chapter after the introduction expands the background of the dissertation by identifying knowledge gaps and research trends while contributing to the generation of a reference database of research experiences, throughout a systematic literature review of cooling research in office buildings during the last 25 years. On the other hand, the following chapter delves specifically in the main themes addressed within the dissertation, proposing a framework for the understanding of solar cooling integrated façades. This considers the theoretical discussion of the concept of architectural façade integration; and the identification of the main working principles and technical components from most common solar cooling technologies, based on a state-of-the-art review. The second part explores different required inputs for façade integration. Design and construction requirements for façade integration are explored; while the response from façade design parameters to various climate conditions is assessed in parallel. The exploration of design and construction requirements is conducted through the identification of the main perceived problems for the façade integration of building services and solar technologies, by means of a survey addressed to façade professionals. On the other hand, a separate chapter explores the relation between climate conditions and cooling requirements in office buildings, evaluating the potential impact of several passive cooling strategies in various warm climates, as a first step before considering further technologies. This was conducted through the statistical analysis of reported research experiences, and dynamic energy simulations of a base scenario using specialised software. The third part of the dissertation consists of two chapters that incorporate previous outcomes for the evaluation of selected solar cooling technologies in terms of current possibilities and constraints for the development of integrated façades. The first of these chapters showcases a qualitative evaluation of the façade integration potential of several solar cooling technologies, based on a comprehensive review of key aspects of each technology and their prospects to overcome the identified barriers for façade integration. This is complemented by a feasibility assessment of integrated concepts in several climates, throughout numerical calculations based on climate data and building scenarios simulated with specialised software; showcased in the following and final chapter. The driving force of the research project is the intention to test the limits of solar cooling integration in façades, showcasing current possibilities while identifying technical constrains and barriers to overcome for the widespread application of integrated façade concepts. Although interesting prospects were identified in this dissertation, important technical constraints need to be solved to conceive a façade component fail-tested for application in buildings. Furthermore, several barriers related to the façade design and development process would need to be tackled in order to introduce architectural products such as these into the building market. The identification and discussion of these barriers, along with the definition of technology driven development paths and recommendations for the generation of distinct architectural products, are regarded as the main outcomes of this dissertation, serving as a compass to guide further explorations in the topic, under an overall environmentally conscious design approach. &nbsp

COOLFACADE: Architectural Integration of Solar Cooling Technologies in the Building Envelope

The thesis ‘COOLFACADE – Architectural integration of solar cooling strategies in the building envelope’ aims to shed light on the possibilities and constraints for architectural integration of solar cooling systems in façades, in order to support the design of climate responsive architectural products for office buildings as self-sufficient alternatives to conventional air-conditioning systems. Increasing cooling needs in the built environment present an important and complex challenge for the design of sustainable buildings and cities. Even though the first course of action should always aim to reduce energy consumption through saving measures and passive design, this is often not enough to avoid mechanical equipment altogether, particularly in the case of office buildings in warm climate contexts. Solar cooling technologies have been increasingly explored, as an environmentally friendly alternative to harmful refrigerants used within vapour compression systems; while also being driven by solar, thus, renewable energy. The principles behind some of these technologies have been researched for over a century, reaching mature solutions and components, and being recognised as promising alternatives to common air-conditioning units. Nonetheless, building application remains mostly limited to demonstration projects and pilot experiences. Recently, façade integrated concepts have been explored, as a way to promote widespread application throughout the development of multifunctional building components. However, while these are regarded as relevant and promising standalone concepts, further research is still needed to assess the integration potential of diverse solar cooling technologies, and identify barriers to overcome, in order to promote the widespread application of solar cooling components in the built environment. The aim of this research project is to explore the possibilities and constraints for architectural integration of solar cooling strategies in façades, in order to support the design of climate responsive architectural products for office buildings, without compromising the thermal comfort of users. The underlying hypothesis then is that self-sufficient solar cooling integrated facades may be a promising alternative to conventional centralised air-conditioning systems widely used in office buildings in warm climates. Most research efforts on solar cooling currently deal with the optimisation of the systems in terms of their performance, testing new materials and simplifying their operation to increase reported efficiencies. However, there is a lack of knowledge on the requirements and current limits for widespread façade application. In order to achieve the research goal and comprehensively assess the façade integration potential of solar technologies and discuss current barriers, different aspects must be acknowledged. These distinct aspects are addressed through several research questions, which in turn define the different chapters of the dissertation. Introduction and conclusions aside, the research body is structured on three sequential parts, with 2-3 chapters each. The first part deals with the state-of-the-art in the field and the theoretical framework, laying the groundwork for the following sections. The second part explores different aspects required as input for façade integration; while the third part comprises the evaluation of solar cooling technologies in terms of current possibilities and constraints for the development of integrated façades, based on the inputs identified in the second part. Furthermore, all chapters were published or submitted for publication as scientific articles in peer review academic journals. The first part considers two chapters that lay the foundations for the research project, The first chapter after the introduction expands the background of the dissertation by identifying knowledge gaps and research trends while contributing to the generation of a reference database of research experiences, throughout a systematic literature review of cooling research in office buildings during the last 25 years. On the other hand, the following chapter delves specifically in the main themes addressed within the dissertation, proposing a framework for the understanding of solar cooling integrated façades. This considers the theoretical discussion of the concept of architectural façade integration; and the identification of the main working principles and technical components from most common solar cooling technologies, based on a state-of-the-art review. The second part explores different required inputs for façade integration. Design and construction requirements for façade integration are explored; while the response from façade design parameters to various climate conditions is assessed in parallel. The exploration of design and construction requirements is conducted through the identification of the main perceived problems for the façade integration of building services and solar technologies, by means of a survey addressed to façade professionals. On the other hand, a separate chapter explores the relation between climate conditions and cooling requirements in office buildings, evaluating the potential impact of several passive cooling strategies in various warm climates, as a first step before considering further technologies. This was conducted through the statistical analysis of reported research experiences, and dynamic energy simulations of a base scenario using specialised software. The third part of the dissertation consists of two chapters that incorporate previous outcomes for the evaluation of selected solar cooling technologies in terms of current possibilities and constraints for the development of integrated façades. The first of these chapters showcases a qualitative evaluation of the façade integration potential of several solar cooling technologies, based on a comprehensive review of key aspects of each technology and their prospects to overcome the identified barriers for façade integration. This is complemented by a feasibility assessment of integrated concepts in several climates, throughout numerical calculations based on climate data and building scenarios simulated with specialised software; showcased in the following and final chapter. The driving force of the research project is the intention to test the limits of solar cooling integration in façades, showcasing current possibilities while identifying technical constrains and barriers to overcome for the widespread application of integrated façade concepts. Although interesting prospects were identified in this dissertation, important technical constraints need to be solved to conceive a façade component fail-tested for application in buildings. Furthermore, several barriers related to the façade design and development process would need to be tackled in order to introduce architectural products such as these into the building market. The identification and discussion of these barriers, along with the definition of technology driven development paths and recommendations for the generation of distinct architectural products, are regarded as the main outcomes of this dissertation, serving as a compass to guide further explorations in the topic, under an overall environmentally conscious design approach