Wicked problem | EPFL Graph Search

In planning and policy, a wicked problem is a problem that is difficult or impossible to solve because of incomplete, contradictory, and changing requirements that are often difficult to recognize. It refers to an idea or problem that cannot be fixed, where there is no single solution to the problem; and "wicked" denotes resistance to resolution, rather than evil. Another definition is "a problem whose social complexity means that it has no determinable stopping point". Moreover, because of complex interdependencies, the effort to solve one aspect of a wicked problem may reveal or create other problems. Due to their complexity, wicked problems are often characterized by organized irresponsibility. The phrase was originally used in social planning. Its modern sense was introduced in 1967 by C. West Churchman in a guest editorial Churchman wrote in the journal Management Science, either repeating his own coinage or responding to a previous use of the term by Horst Rittel—the origin is

Online Stream Mining for Condition Monitoring in Large Infrastructure Systems

Nils Robin Bouchardon

Supervisory Control and Data Acquisition (SCADA) systems are nowadays widely used in modern industry. Their utility has been proven over the past decades to supervise any automated processes. The scope of applications of such a system has been extended from industrial to infrastructure and facility processes. Classic SCADA systems offer tools to help monitoring and analyzing data from this type of systems, but the existing approaches are often limited to Data Warehousing and Reporting. The main problem of these solutions is that they are not designed to work on online mode and can be seen as batch processing on archived data. In this thesis we study how to link machine learning solutions to SCADA systems on large infrastructures. The solution we propose in this work is a complete framework with its architecture providing a ’toolkit’ with different modules to build online solutions on top of a SCADA system.

2015

Rethinking the house form in poor areas

Joana Rosa Ferreira Leite dos Santos Aleixo

Studying housing requires a multidisciplinary approach in order to come up with comprehensive solutions for physical, social and cultural needs. This thesis intends to bring those needs into the process of creating the house, by proposing a methodology to integrate construction-related, environment, cultural and everyday-life aspects into the definition of individual housing profiles. Furthermore, it intends to show how creating an expert system will allow an incremental construction, by taking into account complex constraints, such as cultural and technical ones, based on a pedagogical and interactive approach towards the inhabitant. This research arises from the low levels of habitability of self-build housing in Ondjiva, in southern Angola. In most cases, houses are not equipped with basic infrastructure and do not adequately respond to climatic demands, which leads to the development of unhealthy environments. Additionally, people live in self-build houses in the city in a contradictory way: on the one hand, by keeping deeply rooted cultural and traditional ways of life and, on the other, by wanting to cut with the traditional image, because it is associated with the opposite of âmodernâ, a term commonly associated to better living conditions. As a result, self-build houses in the city tend to follow Western or more contemporary models, which do not ensure culturally sensitive solutions for local inhabitants. It is urgent to find culturally and technically adequate solutions that will foster sustainable housing construction in these areas, which implies searching for multidisciplinary and holistic solutions, since merely technical solutions can be detrimental to the diversity of ways of life characteristic of contemporary cities; comfortable interior spaces will not be enough if they wonât allow the continuity of cultural specificities. Furthermore, this research was made with the conviction that we can neither change the current building actors nor impose our minimum standards on local peopleâs conception of a house. This could put at risk their specific ways of living and ideal of a house, leading almost certainly to more serious and complex social problems. The creation of an expert system is proposed as a tool to make knowledge available to those who most need it, making it possible for people who already build their own houses to start doing so in an improved and more sustainable way, in a context where experts are nearly almost absent from house building processes. This thesis is addressed to the Kwanyama people â the most predominant ethnic group in the Kwanyama region â and rests on the notion that, without a design oriented towards the inhabitantsâ specific needs, their specific ways of life wonât find the support to exist and develop.

EPFL2016

Smooth Scan: Robust Query Execution with a Statistics-oblivious Access Operator

Renata Borovica-Gajic

Query optimizers depend heavily on statistics representing column distributions to create efficient query plans. In many cases, though, statistics are outdated or non-existent, and the process of refreshing statistics is very expensive, especially for ad-hoc workloads on ever bigger data. This results in suboptimal plans that severely hurt performance. The main problem is that any decision, once made by the optimizer, is fixed throughout the execution of a query. In particular, each logical operator translates into a fixed choice of a physical operator at run-time. In this paper we advocate for continuous adaptation and morphing of physical operators throughout their lifetime, by adjusting their behavior in accordance with the statistical properties of the data. We demonstrate the benefits of the new paradigm by designing and implementing an adaptive access path operator called Smooth Scan, which morphs continuously within the space of traditional index access and full table scan. Smooth Scan behaves similarly to an index scan for low selectivity; if selectivity increases, however, Smooth Scan progressively morphs its behavior toward a sequential scan. As a result, a system with Smooth Scan requires no access path decisions up front nor does it need accurate statistics to provide good performance. We implement Smooth Scan in PostgreSQL and, using both synthetic benchmarks as well as TPC-H, we show that it achieves robust performance while at the same time being statistics-oblivious.

2014

Rethinking the house form in poor areas

Joana Rosa Ferreira Leite dos Santos Aleixo

EPFL2016