Abstract: The present disclosure provides, among other things, a method for generating a simulated aggregate based on one or more input parameters. A test aggregate is constructed and rotated. Stable orientations of the aggregate on a surface are determined. In specific examples, two-dimensional properties are calculated for stable orientations of the test aggregate and stored or displayed. In particular implementations of the method, the test aggregate is constructed through successive monomer addition.

Abstract: In various embodiments, the present disclosure provides, among other things, a system and method for influencing the morphology of aggregates. The present disclosure also provides for aggregates formed using the disclosed system and method. According to one disclosed method, a plurality of monomers are provided and an electric field is applied proximate the monomers. The applied fields helps influence the shape of an aggregate formed from the monomers.

Abstract: Photoacoustic instruments and their methods of use are disclosed. Certain disclosed photoacoustic instruments include a resonator cavity, an acoustic detector, a laser, an optical power detector, and a scattering detector. Further disclosed photoacoustic instruments include a resonator cavity, an acoustic detector, an optical power detector, a plurality of laser beams, each laser beam having a different wavelength, and, optionally, a scattering detector.

Abstract: The present disclosure provides, among other things, a method for generating a simulated aggregate based on one or more input parameters. A test aggregate is constructed and rotated. Stable orientations of the aggregate on a surface are determined. In specific examples, two-dimensional properties are calculated for stable orientations of the test aggregate and stored or displayed. In particular implementations of the method, the test aggregate is constructed through successive monomer addition.

Abstract: Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

Abstract: Values for one or more particle properties, such as an aerosol asymmetry parameter g, can be measured directly using a detector that measures scattered light. The detector can comprise two or more diffusers coupled to optical sensors responsive to scattered light that is incident on the surfaces of the diffusers. One or more weighing functions can be obtained based on diffuser geometry. In an example, the diffusers correspond to quadrants of a circular toroid.

Abstract: Photoacoustic instruments and their methods of use are disclosed. Certain disclosed photoacoustic instruments include a resonator cavity, an acoustic detector, a laser, an optical power detector, and a scattering detector. Further disclosed photoacoustic instruments include a resonator cavity, an acoustic detector, an optical power detector, a plurality of laser beams, each laser beam having a different wavelength, and, optionally, a scattering detector.

Abstract: A photoacoustic sensor that measures carbon black particles emitted in the exhaust gas of a vehicle traveling on a road or being tested on a dynamometer or engine stand. The sensor includes an acoustic waveguide and a pump mounted to an outlet of the waveguide. The pump pulls the gas through the waveguide. A critical orifice is mounted between the pump and the outlet. The critical orifice prevents noise generated by the pump from entering the waveguide. Optical windows are mounted at opposite ends of the waveguide. A modulated source of light is located adjacent one of the windows and irradiates the waveguide. A microphone is attached to the waveguide. The microphone detects an acoustic signal generated by absorption of the light by the particles in the gas. The acoustic signal is proportional to the mass concentration of particles in the gas. The microphone generates an electrical signal proportional to the acoustic signal.

Abstract: An apparatus for measuring particles in an exhaust gas of a vehicle. A transmitter is adapted to provide a source of ultraviolet radiation. The radiation travels through the gas and impinges upon the particles in the gas generating a backscattered radiation. The transmitter also generates a timing signal. A receiver is located in proximity of the transmitter. The receiver is adapted to receive the backscattered radiation and to generate a backscattered signal indicative of the quantity of particles entrained in the gas. A data system is connected to the receiver, the data system is adapted to receive the timing signal and the backscattered signal as an input and to calculate a quantity of particles in the gas at a location from the transmitter.

Abstract: A photoacoustic sensor that measures carbon black particles emitted in the exhaust gas of a vehicle traveling on a road or being tested on a dynamometer or engine stand. The sensor includes an acoustic waveguide and a pump mounted to an outlet of the waveguide. The pump pulls the gas through the waveguide. A critical orifice is mounted between the pump and the outlet. The critical orifice prevents noise generated by the pump from entering the waveguide. Optical windows are mounted at opposite ends of the waveguide. A modulated source of light is located adjacent one of the windows and irradiates the waveguide. A microphone is attached to the waveguide. The microphone detects an acoustic signal generated by absorption of the light by the particles in the gas. The acoustic signal is proportional to the mass concentration of particles in the gas. The microphone generates an electrical signal proportional to the acoustic signal.