Investigating Single Precision Floating General Matrix Multiply in Heterogeneous Hardware

The fundamental operation of matrix multiplication is ubiquitous across a myriad of disciplines. Yet, the identification of new optimizations for matrix multiplication remains relevant for emerging hardware architectures and heterogeneous systems. Frameworks such as OpenCL enable computation orchestration on existing systems, and its availability using the Intel High Level Synthesis compiler allows users to architect new designs for reconfigurable hardware using C/C++. Using the HARPv2 as a vehicle for exploration, we investigate the utility of several of the most notable matrix multiplication optimizations to better understand the performance portability of OpenCL and the implications for such optimizations on this and future heterogeneous architectures. Our results give targeted insights into the applicability of best practices that were for existing architectures when used on emerging heterogeneous systems

A robust modeling framework for energy analysis of data centers

Global digitalization has given birth to the explosion of digital services in approximately every sector of contemporary life. Applications of artificial intelligence, blockchain technologies, and internet of things are promising to accelerate digitalization further. As a consequence, the number of data centers, which provide the services of data processing, storage, and communication services, is also increasing rapidly. Because data centers are energy-intensive with significant and growing electricity demand, an energy model of data centers with temporal, spatial, and predictive analysis capability is critical for guiding industry and governmental authorities for making technology investment decisions. However, current models fail to provide consistent and high dimensional energy analysis for data centers due to severe data gaps. This can be further attributed to the lack of the modeling capabilities for energy analysis of data center components including IT equipment and data center cooling and power provisioning infrastructure in current energy models. In this research, a technology-based modeling framework, in hybrid with a data-driven approach, is proposed to address the knowledge gaps in current data center energy models. The research aims to provide policy makers and data center energy analysts with comprehensive understanding of data center energy use and efficiency opportunities and a better understanding of macro-level data center energy demand and energy saving potentials, in addition to the technological barriers for adopting energy efficiency measures

Development and application of a framework for model structure evaluation in environmental modelling

In a fast developing world with an ever rising population, the pressures on our natural environment are continuously increasing, causing problems such as floods, water- and air pollution, droughts,... Insight in the driving mechanisms causing these threats is essential in order to properly mitigate these problems. During the last decades, mathematical models became an essential part of scientific research to better understand and predict natural phenomena. Notwithstanding the diversity of currently existing models and modelling frameworks, the identification of the most appropriate model structure for a given problem remains a research challenge. The latter is the main focus of this dissertation, which aims to improve current practices of model structure comparison and evaluation. This is done by making individual model decisions more transparent and explicitly testable. A diagnostic framework, focusing on a flexible and open model structure definition and specifying the requirements for future model developments, is described. Methods for model structure evaluation are documented, implemented, extended and applied on both respirometric and hydrological models. For the specific case of lumped hydrological models, the unity between apparently different models is illustrated. A schematic representation of these model structures provides a more transparent communication tool, while meeting the requirements of the diagnostic approach

Dual adversarial deconfounding autoencoder for joint batch-effects removal from multi-center and multi-scanner radiomics data

Abstract Medical imaging represents the primary tool for investigating and monitoring several diseases, including cancer. The advances in quantitative image analysis have developed towards the extraction of biomarkers able to support clinical decisions. To produce robust results, multi-center studies are often set up. However, the imaging information must be denoised from confounding factors—known as batch-effect—like scanner-specific and center-specific influences. Moreover, in non-solid cancers, like lymphomas, effective biomarkers require an imaging-based representation of the disease that accounts for its multi-site spreading over the patient’s body. In this work, we address the dual-factor deconfusion problem and we propose a deconfusion algorithm to harmonize the imaging information of patients affected by Hodgkin Lymphoma in a multi-center setting. We show that the proposed model successfully denoises data from domain-specific variability (p-value < 0.001) while it coherently preserves the spatial relationship between imaging descriptions of peer lesions (p-value = 0), which is a strong prognostic biomarker for tumor heterogeneity assessment. This harmonization step allows to significantly improve the performance in prognostic models with respect to state-of-the-art methods, enabling building exhaustive patient representations and delivering more accurate analyses (p-values < 0.001 in training, p-values < 0.05 in testing). This work lays the groundwork for performing large-scale and reproducible analyses on multi-center data that are urgently needed to convey the translation of imaging-based biomarkers into the clinical practice as effective prognostic tools. The code is available on GitHub at this https://github.com/LaraCavinato/Dual-ADAE

High-Dimensional Spatio-Temporal Indexing

There exist numerous indexing methods which handle either spatio-temporal or high-dimensional data well. However, those indexing methods which handle spatio-temporal data well have certain drawbacks when confronted with high-dimensional data. As the most efficient spatio-temporal indexing methods are based on the R-tree and its variants, they face the well known problems in high-dimensional space. Furthermore, most high-dimensional indexing methods try to reduce the number of dimensions in the data being indexed and compress the information given by all dimensions into few dimensions but are not able to store now - relative data. One of the most efficient high-dimensional indexing methods, the Pyramid Technique, is able to handle high-dimensional point-data only. Nonetheless, we take this technique and extend it such that it is able to handle spatio-temporal data as well. We introduce a technique for querying in this structure with spatio-temporal queries. We compare our technique, the Spatio-Temporal Pyramid Adapter (STPA), to the RST-tree for in-memory and on-disk applications. We show that for high dimensions, the extra query-cost for reducing the dimensionality in the Pyramid Technique is clearly exceeded by the rising query-cost in the RST-tree. Concluding, we address the main drawbacks and advantages of our technique

How to Tailor My Process‐Based Hydrological Model? Dynamic Identifiability Analysis of Flexible Model Structures

In the field of hydrological modeling, many alternative representations of natural processes exist. Choosing specific process formulations when building a hydrological model is therefore associated with a high degree of ambiguity and subjectivity. In addition, the numerical integration of the underlying differential equations and parametrization of model structures influence model performance. Identifiability analysis may provide guidance by constraining the a priori range of alternatives based on observations. In this work, a flexible simulation environment is used to build an ensemble of semidistributed, process-based hydrological model configurations with alternative process representations, numerical integration schemes, and model parametrizations in an integrated manner. The flexible simulation environment is coupled with an approach for dynamic identifiability analysis. The objective is to investigate the applicability of the framework to identify the most adequate model. While an optimal model configuration could not be clearly distinguished, interesting results were obtained when relating model identifiability with hydro-meteorological boundary conditions. For instance, we tested the Penman-Monteith and Shuttleworth & Wallace evapotranspiration models and found that the former performs better under wet and the latter under dry conditions. Parametrization of model structures plays a dominant role as it can compensate for inadequate process representations and poor numerical solvers. Therefore, it was found that numerical solvers of high order of accuracy do often, though not necessarily, lead to better model performance. The proposed coupled framework proved to be a straightforward diagnostic tool for model building and hypotheses testing and shows potential for more in-depth analysis of process implementations and catchment functioning

Improving Country Conflict and Peace Modeling: Datasets, Imputations, and Hierarchical Clustering

Many disparate datasets exist that provide country attributes covering political, economic, and social aspects. Unfortunately, this data often does not include all countries nor is the data complete for those countries included, as measured by the dataset’s missingness. This research addresses these dataset shortfalls in predicting country instability by considering country attributes in all aspects as well as in greater thresholds of missingness. First, a structured summary of past research is presented framed by a developed casual taxonomy and functional ontology. Additionally, a novel imputation technique for very large datasets is presented to account for moderate missingness in the expanded dataset. This method is further extended to establish the MASS-impute algorithm, a multicollinearity applied stepwise stochastic imputation method that overcomes numerical problems present in preferred commercial packages. Finally, the imputed datasets with 932 variables are used to develop a hierarchical clustering approach that accounts for geographic and cultural influences that are desired in the practical use of modeling country conflict. These additional insights and tools provide a basis for improving future country conflict and peace research

Mass Customization Strategies And Their Relationship To Lean Production In The Homebuilding Industry

Current housing trends point to an increasing interest from homebuyers to demand houses that reflect their personal and unique styles, and which are individually configured according to these needs (NAHB, 2004). These homebuyers in turn are unwilling to settle for standard models that sacrifice what they really want in a home. At the same time this creates pressure on builders who are reluctant to sacrifice production efficiencies by deviating from standard models. Such customization desired by demanding customers can disrupt the entire estimating, production, delivery and management process, making it even more difficult to manage homebuilding efficiently and effectively. The question faced by homebuilders in this conditions is, how to manage this trade-off and deliver exactly what homebuyers want, at reasonable prices and lead times with minimal disruptions in efficiencies. Mass Customization (MC) is an emerging production paradigm that seeks to manage the trade-offs between product variety and mass efficiency, while fulfilling individual customer requirements. The general purpose of this research is to improve the effectiveness and efficiency of housing production through the implementation of mass customization strategies. More specifically, this research focuses on the study of the production system through the application of lean production principles, as an approach to enable mass customization. This study first characterizes how much product choice is currently being offered by U.S. homebuilders and what is the impact of customization on production efficiency; and then focuses on the evaluation of the relationships between mass customization and lean production principles. Results revealed that homebuilders offering increased product choice are likely to suffer poorer labor productivity, greater inventory, higher production costs, more quality issues, less satisfied homebuyers, and lower space efficiency. In general, operational performance deteriorated with an increase in product choice. Therefore, industrialized housing manufacturers have not reached the ideal of mass customization and are paying a price for offering more choices to their customers. Homebuilders could mitigate these challenges by using lean concepts. In general, case studies showed that product choice does not necessarily make the implementation of lean concepts more difficult. Some lean concepts, like workload balancing and standardizing tasks, clearly facilitated the handling of product choice. Other lean concepts, like creating a continuous process flow, can be made to work well, even with increased choice. Case study results suggested that good concepts for lean (e.g., efficient continuous flow, effective pull system, workload leveling, defect-free processes, standard tasks, good visual controls, and reliable technology) were also good concepts for (or easily accommodated) handling a range of product choice