Characterization of fine particle emissions from incense burning

Incense burning is an important indoor source of airborne particles. In this study, the emission factors of PM_2.5 and its chemical constituents emitted from six different brands of incense sticks were determined. Controlled experiments were conducted to measure the mass concentration of PM_2.5 and to determine its chemical composition (elemental carbon (EC), organic carbon (OC), metals, and ions). Measurements showed that the emissions vary for different brands of incense sticks, with smokeless incense sticks emitting the least amount. PM_2.5 emission factors range from 0.4 (smokeless incense stick) to 44.5 mg/g. Results also show that the amount of metals emitted is highly dependent on the quantity of metals present in the incense sticks. In addition, the information obtained from the controlled experiments is used to predict the concentration of PM_2.5 at incense smoke-influenced microenvironments, such as temples and homes, in order to assess the potential indoor exposure during the course of incense burning. Comparison with indoor air quality guidelines suggests that inhalation of incense smoke can pose adverse health impacts.     

Rugged Soft Robots using Tough,Stretchable, and Self-Healable Adhesive Elastomers

Soft robots are susceptible to premature failure from physical damages incurred within dynamic environments. To address this, we report an elastomer with high toughness, room temperature self-healing, and strong adhesiveness, allowing both prevention of damages and recovery for soft robotics. By functionalizing polyurethane with hierarchical hydrogen bonds from ureido-4[1H]-pyrimidinone (UPy) and carboxyl groups, high toughness (74.85 MJ m⁻³), tensile strength (9.44 MPa), and strain (2340%) can be achieved. Furthermore, solvent-assisted self-healing at room temperature enables retention of high toughness (41.74 MJ m⁻³), tensile strength (5.57 MPa), and strain (1865%) within only 12 h. The elastomer possesses a high dielectric constant (≈9) that favors its utilization as a self-healing dielectric elastomer actuator (DEA) for soft robotics. Displaying high area strains of ≈31.4% and ≈19.3% after mechanical and electrical self-healing, respectively, the best performing self-healable DEA is achieved. With abundant hydrogen bonds, high adhesive strength without additional curing or heating is also realized. Having both actuation and adhesive properties, a “stick-on” strategy for the assembly of robust soft robots is realized, allowing soft robotic components to be easily reassembled or replaced upon severe damage. This study highlights the potential of soft robots with extreme ruggedness for different operating conditions.     

An image-rejection down-converter for low-IF receivers

Implemented in 4.1 mm² in 130-nm CMOS, a dual-conversion image-rejection down-converter applied to the wireless code-division multiple-access (WCDMA) standard draws 13 mA from a single 1.8-V power supply. Using an IF of 2.5 MHz, the WCDMA image-rejection band is widened from 0.58-4.42 MHz to 0.48-5.2 MHz-a bandwidth ratio of 10.8-to accommodate process, voltage, and temperature variations in high-volume production. Ten samples are measured and fully characterized: average image-rejection ratio (IRR) is 46.6 dBc, gain is 12 dB, and noise figure is 10.8 dB. Typical IRR is 44.8, 46.5, and 47.5 dBc at -20degC, 25degC, and 80degC, respectively     

Privacy-preserving e-payments using one-time payment details

The recent increase in data breaching incidents involving high profile e-commerce companies is alarming as such privacy threats can seriously thwart the healthy growth of electronic commerce. We propose a privacy-preserving e-payment scheme that guarantees authenticity while keeping the customer’s sensitive details secret from the respective parties involved in the online transaction. Using a non-reusable password-based authentication approach, the proposed protocol allows consumers to anonymously purchase goods from an online merchant, thus achieving the ideal privacy environment in which to shop. The protocol can be easily deployed in an e-commerce environment without requiring great changes to the current processes.     

Compact‐size linearly tapered slot antenna for portable ultra‐wideband imaging systems

A compact‐size asymmetrical linearly tapered slot antenna required for portable ultra‐wideband (UWB) imaging systems is presented. The total antenna size is reduced compared with the conventional linearly tapered slot antenna by using a triangular slot on the left‐hand side of the tapered‐shaped radiator, whereas introducing a corrugated pattern of cuts on the right side. The antenna operates over a wide bandwidth extending from 3.1 to 10.6 GHz with a maximum gain of 8.5 dBi. Stable radiation patterns are observed across the operational bandwidth, with cross‐polarization levels below ?20 dB. The realized antenna structure occupies a volume of 35 × 36 × 0.8 mm³, and possesses the essential time domain fidelity needed for UWB imaging applications. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.