value, because the loss of the up-leading sensors will make it difficult to measure the reflectivity of the FBGs in the rear positions. However, by utilizing the SDM, more than one optical fiber can be connected to the interrogator. The configuration is demonstrated in Figure 1. An additional merit of this technique is that FBG sensors can be incorporated into this system and interrogated at the same time with a resolution of 1 pm. The intensity-type sensors and FBG sensors can be hybrid-interrogated if only the wavelengths of FBGs on one fiber are different. This merit would be useful when the two kinds of sensors are necessary in one measurement system. CONCLUSIONIn conclusion, a novel multiplexing method for intensity-type fiber-optic sensors based on a hybrid WDM/SDM approach is proposed and demonstrated. The sensor head is composed of two FBGs with different wavelengths and one intensity-type sensor. The loss induced by the measurand is interrogated by measuring the reflectivity of the two FBGs and by calculating the ratio. The experimental results show that the sensor in the up-leading position has no influence on the sensor in the rear position. It is anticipated that such an intensity-type of sensor could be used for a wide range of applications, in particular, as a hydrogen sensor, evanescent sensor, and chemical sensor. [5,6]. In this article, an alternative novel design of small microstripline-fed slot antenna with dual-band operations is proposed. The size of the proposed antenna can be greatly reduced by implanting grounded crossed strips in the slot of a conventional printed square slot antenna (PSSA). Although the resulting antenna size is not as small as those presented in Refs. ACKNOWLEDGMENTS This work was supported by the Program for New Century Excellent Talents in the University (NCET) of China and Chinese 863 Project (2008AA04Z406[5] and [6], the design procedure presented here is relatively simple and systematic. The grounded strips can excite two resonant modes having different electric current distributions in the metal region (consisting of both the ground plane and the strips) so as to form two disjointed resonant bands. One resonant band is lower than that of the fundamental resonant mode of the corresponding conventional PSSA, and the other is higher. The center-frequency ratio of the two resonant bands can be easily adjusted by changing the dimensions of the strips. A large range of dual-frequency ratios (1.8 -2.6) can easily be obtained. An antenna prototype has been successfully designed and fabricated for 2.45/5.25 GHz dual-band (2400 -2484 MHz and 5150 -5350 MHz) WLAN applications. Figure 1 shows the geometry of the proposed microstripline-fed PSSA, where the square slot with a side length of L ϭ 22 mm is etched from the conductor of a grounded square substrate with a side length of 40 mm, a thickness of h ϭ 0.7 mm, a dielectric constant of r ϭ 4.2, and a loss tangent of tan ␦ ϭ 0.02. Connected to the two upper inner corners of the ground are two 1-mm-wide conducting strips tha...
Decades of air quality improvements have substantially reduced the motor vehicle emissions of volatile organic compounds (VOCs). Today, volatile chemical products (VCPs) are responsible for half of the petrochemical VOCs emitted in major urban areas. We show that VCP emissions are ubiquitous in US and European cities and scale with population density. We report significant VCP emissions for New York City (NYC), including a monoterpene flux of 14.7 to 24.4 kg ⋅ d−1 ⋅ km−2 from fragranced VCPs and other anthropogenic sources, which is comparable to that of a summertime forest. Photochemical modeling of an extreme heat event, with ozone well in excess of US standards, illustrates the significant impact of VCPs on air quality. In the most populated regions of NYC, ozone was sensitive to anthropogenic VOCs (AVOCs), even in the presence of biogenic sources. Within this VOC-sensitive regime, AVOCs contributed upwards of ∼20 ppb to maximum 8-h average ozone. VCPs accounted for more than 50% of this total AVOC contribution. Emissions from fragranced VCPs, including personal care and cleaning products, account for at least 50% of the ozone attributed to VCPs. We show that model simulations of ozone depend foremost on the magnitude of VCP emissions and that the addition of oxygenated VCP chemistry impacts simulations of key atmospheric oxidation products. NYC is a case study for developed megacities, and the impacts of VCPs on local ozone are likely similar for other major urban regions across North America or Europe.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.