Vi utgår från observationer av universum och vår planet för att utveckla modeller och verktyg som möter globala utmaningar kring resurser, energiförsörjning och klimatpåverkan.
Vart är vi på väg? Var kommer vi ifrån? På vår institution söker vi svaren på de riktigt stora frågorna. I ett långt tidsperspektiv ger stjärnor och galaxers livscykler en inblick i universums, jordens och livets uppkomst – och framtid. Vi observerar också vår planet och samspelet mellan samhälle, teknik och natur för att kunna utveckla teknik, modeller och verktyg som kan möta globala utmaningar inom naturresurser, klimatpåverkan och energiförsörjning.
Observes the universe and our planet, to develop models and tools that meet global challenges regarding resources, energy supply and climate impact.
Where do we come from and where are we going? At our department we search for answers to the really big questions. In a long time perspective, the lifecycles of stars and galaxies provide an insight into the origin and future of the universe, earth and life. We also observe our planet and the interaction between society, technology and nature in order to develop technologies, models and tools that can meet global challenges regarding natural resources, climate impact and energy supply.
(2020) Ghalebani, Mehdi; Chalmers tekniska högskola / Institutionen för rymd-, geo- och miljövetenskap; Mellqvist, Johan
Over the recent decade, Emergence and commercialization of the new, low-cost, sensor
technologies have created the possibility of major paradigm shifts in air quality
monitoring. Their price of three orders of magnitude lower than standard/reference
instruments provides the opportunity for new applications such as higher geographical
and temporal resolutions of the measurements. There have been studies on the
performance of a network of these sensors, however, their individual reliability is
still questionable. This study aimed to evaluate the performance of one of the most
common low-end sensors available on the market, SDS011, as well as a middle-end
sensor, SDS019 under different circumstances such as temperature and humidity.
The main research questions were: how reliable are these sensors and what are the
causes of errors for these sensors and is it possible to find correction factors based on
meteorological data? To address the research questions, a range of experiments in
different environments, including field and laboratory, have been conducted under
several humidity and temperatures. The results of the experiments illustrated a
high linear correlation between the SDS011 and SDS019 sensors with the reference
sensor(Optical Particle Sizer) at laboratory experiments. The data were fitted to the
reference sensor using a linear regression model. additionally, a multiple linear regression
was applied to include the temperature and relative humidity as additional
input parameters to the regression model. The results of the multiple and normal
regression were compared and discussed under different circumstances for both
SDS011 and SDS019 sensors. The field experiments showed significant differences
between the SDS011 and reference instruments and these could not be explained
by humidity alone. They were not significantly reduced when applying laboratory
correction factors either. A three week comparison of the SDS011 against the golden
standard for PM in air quality monitoring (TEOM) showed periods with both decent
and poor agreement, illustrating that the SDS011 sensors respond to PM but
that they are rather unreliable when used as single devices. Further research work
is needed to understand this. Nevertheless the sensors are suitable for operation in
a network to obtain spatial air quality information , both as stationary and mobile.