Reliability of urban microclimate simulations: spatio-temporal validation through intra-urban canyon transects for outdoor thermal comfort analysis.

Mitigating Urban Heat Island (UHI) intensity in cities through adaptative strategies has become an urgent need, as UHI are also exacerbated by climate change impacts imputable to anthropogenic actions. This study addresses the need for reliable simulation models to analyze outdoor thermal comfort (OTC) in future or alternative scenarios. The aim of the present study is to contribute to the validation of CFD urban microclimate simulations by employing intra-urban canyon transects as an alternative or a complementary approach to fixed stations. To accomplish this, we developed a cost-effective monitoring unit to carry out transects on a pre-defined route (1), devised the area of interest (2), elaborated a simulation model in ENVI-met (3), and proposed different validation methods for comparative analyses (4). Results indicate that temporal validated simulation tended to underestimate thermal indices in the morning and night and overestimate them in the afternoon, while spatio-temporal validation under a human-centric comfort approach via wearable sensing notably improved accuracy. Moderate to very strong agreement between simulation and measurement data in summer (Willmot's d ~ 0.70, d ~ 0.81) and very strong agreement in winter (d ~ 0.79, d ~ 0.96), with low error magnitudes in summer (RMSE ~ 0.91℃ and 9.59%, MBE ~ 0.23℃ and 9.10%) have been found. In winter, such figures were RMSE ~ 0.71℃ and 3.51%, MBE ~ 0.00℃ and 0.98%, for the spatio-temporal validated model. This research contributes to enhancing the reliability of relatively affordable CFD urban microclimate simulations, supporting its scale up for policymakers in implementing effective strategies for OTC.

Measuring Dynamic Signals with Direct Sensor-to-Microcontroller Interfaces Applied to a Magnetoresistive Sensor.

This paper evaluates the performance of direct interface circuits (DIC), where the sensor is directly connected to a microcontroller, when a resistive sensor subjected to dynamic changes is measured. The theoretical analysis provides guidelines for the selection of the components taking into account both the desired resolution and the bandwidth of the input signal. Such an analysis reveals that there is a trade-off between the sampling frequency and the resolution of the measurement, and this depends on the selected value of the capacitor that forms the RC circuit together with the sensor resistance. This performance is then experimentally proved with a DIC measuring a magnetoresistive sensor exposed to a magnetic field of different frequencies, amplitudes, and waveforms. A sinusoidal magnetic field up to 1 kHz can be monitored with a resolution of eight bits and a sampling frequency of around 10 kSa/s. If a higher resolution is desired, the sampling frequency has to be lower, thus limiting the bandwidth of the dynamic signal under measurement. The DIC is also applied to measure an electrocardiogram-type signal and its QRS complex is well identified, which enables the estimation, for instance, of the heart rate.