Particle collection efficiency of a lens-liquid filtration system

Clinical and epidemiological studies have shown that indoor air quality has substantial impact on the health of building occupants [1]. Possible sources of indoor air contamination include hazardous gases as well as particulate matters (PMs) [2]. Experimental studies show that the size distribution of PMs in indoor air ranges from tens of nanometers to a few hundreds of micrometers [3]. Vacuum cleaners can be used as a major tool to collect PMs from floor/carpets, which are the main sources of indoor PMs. However, the particle collection efficiency of typical cyclonic filters in the vacuums drops significantly for particles of diameter below 10 μm. In this work, we propose a lens-liquid filtration system (see Figure 1), where the flow channel is formed by a liquid free surface and a planar plate with fin/lens structures. Computational fluid dynamics simulations are performed by using FLUENT to optimize the structure of the proposed system toward high particle collection efficiency and satisfactory pressure drop. Numerical simulations show that the system can collect 250 nm diameter particles with collection efficiency of 50%. © 2011 American Institute of Physics

Numerical Simulation on the Particle Collection Efficiency of a Lens-Liquid Filtration System

Clinical and epidemiological studies have shown that indoor air quality has substantial impact on the health of building occupants [1]. Possible sources of indoor air contamination include hazardous gases as well as particulate matters (PMs) [2]. Experimental studies show that the size distribution of PMs in indoor air ranges from tens of nanometers to a few hundreds of micrometers [3]. Vacuum cleaners can be used as a major tool to collect PMs from floor/carpets, which are the main sources of indoor PMs. However, the particle collection efficiency of typical cyclonic filters in the vacuums drops significantly for particles of diameter below 10 μm. In this work, we propose a lens-liquid filtration system (see Figure 1), where the flow channel is formed by a liquid free surface and a planar plate with fin/lens structures. Computational fluid dynamics simulations are performed by using FLUENT to optimize the structure of the proposed system toward high particle collection efficiency and satisfactory pressure drop. Numerical simulations show that the system can collect 250 nm diameter particles with collection efficiency of 50%. © 2011 American Institute of Physics

New digital watermarking for few-color images

In this paper, we propose a new digital watermarking algorithm named Spatial Unified Key Insertion (SUKI) for few-color images. By performing the adaptive threshold halftoning and contour shaping and modification, we can embed a binary logo into a digital image with superior JPEG compression resistance ability. The Bit Error Rate (BER) of JPEG attack is equal to zero for all testing images with Quality Factor ≥ 80. The BER is much lower than the traditional watermarking algorithms, such as Spread Spectrum Watermarking and Quantization Index Modulation Watermarking. The payload is considerably high and there are no "salt-and-peppers" artifacts in the watermarked images. No additional color is introduced and the palette keeps unchanged after watermark embedding. The proposed algorithm can be applied to natural images with distinct boundaries by segmenting the images into different parts. ©2006 IEEE