Development of cellphone integrated particulate matter pollution monitoring unit

In this thesis, a miniature particulate matter detector is developed. The design utilizing light scattering (Mie Theory) phenomenon as the working principle measures mass concentration of particles with preselected size. The selection is realized by a special designed virtual impactor which collects particles within a range of desired physical sizes (10 micrometers or less). Theories corresponding to physical phenomenon are explained in detail. Parameter of each equation and procedure of design are elaborated. The miniature PM monitoring unit achieves one-fifth of the size of the smallest commercial product in the market. All selected components (fan, laser, photodiode) are DC powered and lower wattage, which is made possible for phone battery as the power supply. Sensing range exceeds the worst PM10 reading in the history, and with sensitivity of 0.3μg/m3, the air quality level can be divided into ten or more levels. Special designed virtual impactor separates PM10 from other air laden particles with low particle loss.

Development of cellphone integrated particulate matter pollution monitoring unit

In this thesis, a miniature particulate matter detector is developed. The design utilizing light scattering (Mie Theory) phenomenon as the working principle measures mass concentration of particles with preselected size. The selection is realized by a special designed virtual impactor which collects particles within a range of desired physical sizes (10 micrometers or less). Theories corresponding to physical phenomenon are explained in detail. Parameter of each equation and procedure of design are elaborated. The miniature PM monitoring unit achieves one-fifth of the size of the smallest commercial product in the market. All selected components (fan, laser, photodiode) are DC powered and lower wattage, which is made possible for phone battery as the power supply. Sensing range exceeds the worst PM10 reading in the history, and with sensitivity of 0.3μg/m3, the air quality level can be divided into ten or more levels. Special designed virtual impactor separates PM10 from other air laden particles with low particle loss.

A Phase Separation Inlet for Droplets, Ice Residuals, and Interstitial Aerosol Particles

A new inlet for studying the aerosol particles and hydrometeor residuals that compose mixed-phase clouds – the phaSe seParation Inlet for Droplets icE residuals and inteRstitial aerosol particles (SPIDER) – is described here. SPIDER combines a Large-Pumped Counterflow Virtual Impactor (L-PCVI), a flow tube evaporation chamber, and a Pumped Counterflow Virtual Impactor (PCVI) to separate droplets, ice crystals, and interstitial aerosol particles for simultaneous sampling. Laboratory verification tests of each individual component and then the composite SPIDER system were conducted. SPIDER was then deployed at Storm Peak Laboratory (SPL), a mountain-top research facility at 3210 m a.s.l. in the Rocky Mountains. SPIDER performance as a field instrument is presented with data that demonstrates its capability of separating cloud elements and interstitial aerosol particle. Possible design improvements of SPIDER are also suggested.

Dozens of virtual impactor orbits eliminated by the EURONEAR VIMP DECam data mining project

Context. Massive data mining of image archives observed with large etendue facilities represents a great opportunity for orbital amelioration of poorly known virtual impactor asteroids (VIs). There are more than 1000 VIs known today; most of them have very short observed arcs and many are considered lost as they became extremely faint soon after discovery. Aims. We aim to improve the orbits of VIs and eliminate their status by data mining the existing image archives. Methods. Within the European Near Earth Asteroids Research (EURONEAR) project, we developed the Virtual Impactor search using Mega-Precovery (VIMP) software, which is endowed with a very effective (fast and accurate) algorithm to predict apparitions of candidate pairs for subsequent guided human search. Considering a simple geometric model, the VIMP algorithm searches for any possible intersection in space and time between the positional uncertainty of any VI and the bounding sky projection of any image archive. Results. We applied VIMP to mine the data of 451,914 Blanco/DECam images observed between 12 September 2012 and 11 July 2019, identifying 212 VIs that possibly fall into 1286 candidate images leading to either precovery or recovery events. Following a careful search of candidate images, we recovered and measured 54 VIs in 183 DECam images. About 4,000 impact orbits were eliminated from both lists, 27 VIs were removed from at least one list, while 14 objects were eliminated from both lists. The faintest detections were around V ∼ 24.0, while the majority fall between 21 < V < 23. The minimal orbital intersection distances remains constant for 67% detections, increasing for eight objects and decreasing for ten objects. Most eliminated VIs (70%) had short initial arcs of less than five days. Some unexpected photometric discovery has emerged regarding the rotation period of 2018 DB, based on the close inspection of longer trailed VIs and the measurement of their fluxes along the trails. Conclusions. Large etendue imaging archives represent great assets to search for serendipitous encounters of faint asteroids and VIs.