TY  - CHAP
A1  - Dey, Thomas
A1  - Elsen, Ingo
A1  - Ferrein, Alexander
A1  - Frauenrath, Tobias
A1  - Reke, Michael
A1  - Schiffer, Stefan
ED  - Makedon, Fillia
T1  - CO2 Meter: a do-it-yourself carbon dioxide measuring device for the classroom
T2  - PETRA '21: Proceedings of the 14th Pervasive Technologies Related to Assistive Environments Conference
N2  - In this paper we report on CO2 Meter, a do-it-yourself carbon dioxide measuring device for the classroom. Part of the current measures for dealing with the SARS-CoV-2 pandemic is proper ventilation in indoor settings. This is especially important in schools with students coming back to the classroom even with high incidents rates. Static ventilation patterns do not consider the individual situation for a particular class. Influencing factors like the type of activity, the physical structure or the room occupancy are not incorporated. Also, existing devices are rather expensive and often provide only limited information and only locally without any networking. This leaves the potential of analysing the situation across different settings untapped. Carbon dioxide level can be used as an indicator of air quality, in general, and of aerosol load in particular. Since, according to the latest findings, SARS-CoV-2 can be transmitted primarily in the form of aerosols, carbon dioxide may be used as a proxy for the risk of a virus infection. Hence, schools could improve the indoor air quality and potentially reduce the infection risk if they actually had measuring devices available in the classroom. Our device supports schools in ventilation and it allows for collecting data over the Internet to enable a detailed data analysis and model generation. First deployments in schools at different levels were received very positively. A pilot installation with a larger data collection and analysis is underway.
KW  - embedded hardware
KW  - sensor networks
KW  - information systems
KW  - education
KW  - do-it-yourself
Y1  - 2021
SN  - 9781450387927
U6  - https://doi.org/10.1145/3453892.3462697
N1  - PETRA '21: The 14th PErvasive Technologies Related to Assistive Environments Conference Corfu Greece 29 June 2021- 2 July 2021
SP  - 292
EP  - 299
PB  - Association for Computing Machinery
CY  - New York
ER  - 
TY  - JOUR
A1  - Fiedler, Thomas M.
A1  - Orzada, Stephan
A1  - Flöser, Martina
A1  - Rietsch, Stefan H. G.
A1  - Quick, Harald H.
A1  - Ladd, Mark E.
A1  - Bitz, Andreas
T1  - Performance analysis of integrated RF microstrip transmit antenna arrays with high channel count for body imaging at 7 T
JF  - NMR in Biomedicine
N2  - The aim of the current study was to investigate the performance of integrated RF
transmit arrays with high channel count consisting of meander microstrip antennas
for body imaging at 7 T and to optimize the position and number of transmit ele-
ments. RF simulations using multiring antenna arrays placed behind the bore liner
were performed for realistic exposure conditions for body imaging. Simulations were
performed for arrays with as few as eight elements and for arrays with high channel
counts of up to 48 elements. The B1+ field was evaluated regarding the degrees of
freedom for RF shimming in the abdomen. Worst-case specific absorption rate
(SARwc ), SAR overestimation in the matrix compression, the number of virtual obser-
vation points (VOPs) and SAR efficiency were evaluated. Constrained RF shimming
was performed in differently oriented regions of interest in the body, and the devia-
tion from a target B1+ field was evaluated. Results show that integrated multiring
arrays are able to generate homogeneous B1+ field distributions for large FOVs, espe-
cially for coronal/sagittal slices, and thus enable body imaging at 7 T with a clinical
workflow; however, a low duty cycle or a high SAR is required to achieve homoge-
neous B1+ distributions and to exploit the full potential. In conclusion, integrated
arrays allow for high element counts that have high degrees of freedom for the pulse
optimization but also produce high SARwc , which reduces the SAR accuracy in the
VOP compression for low-SAR protocols, leading to a potential reduction in array
performance. Smaller SAR overestimations can increase SAR accuracy, but lead to a
high number of VOPs, which increases the computational cost for VOP evaluation
and makes online SAR monitoring or pulse optimization challenging. Arrays with
interleaved rings showed the best results in the study.
KW  - body imaging at UHF MRI
KW  - integrated transmit coil arrays
KW  - VOP compression
Y1  - 2021
U6  - https://doi.org/10.1002/nbm.4515
SN  - 0952-3480 (ISSN)
SN  - 1099-1492 (eISSN)
VL  - 34
IS  - 7
PB  - Wiley
CY  - Weinheim
ER  -