Spatial Factors Affecting the Frequency of Pedestrian Traffic Crashes: A Systematic Review

Context: Considering the importance of pedestrian traffic crashes and the role of environmental factors in the frequency of crashes, this paper aimed to review the published evidence and synthesize the results of related studies for the associations between environmental factors and distribution of pedestrian-vehicular traffic crashes. Evidence Acquisition: We searched all epidemiological studies from 1966 to 2015 in electronic databases. We found 2,828 studies. Only 15 observational studies out of these studies met the inclusion criteria of the study. The quality of the included studies was assessed using the strengthening the reporting of observational studies in epidemiology (STROBE) checklist. Results: A review of the studies showed significant correlations between a large number of spatial variables including student population and the number of schools, population density, traffic volume, roadway density, socio-economic status, number of intersections, and the pedestrian volume and the dependent variable of the frequency of pedestrian traffic crashes. In the studies, some spatial factors that play an important role in determining the frequency of pedestrian traffic crashes, such as facilities for increasing the pedestrians’ safety were ignored. Conclusions: It is proposed that the needed research be conducted at national and regional levels in coordination and cooperation with international organizations active in the field of traffic crashes in various parts of the world, especially in Asian, African and Latin American developing countries, where a greater proportion of pedestrian traffic crashes occur

Front-end components design for IEEE 802.11B/G, Applications using an MMIC technology

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A Fully Integrated SiGe BiCMOS MMIC Front-end for Using in the ISM Bands

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A 2.4-GHz Front-end System Design for WLAN Applications using 0.35μm SiGe BiCMOS Technology

International audienceA 2.4GHz front-end system design for wide spectrum WLAN applications is presented in a 0.35 μm SiGe BiCMOS Technology. This transceiver front-end contains a receive (Rx) chain with a two-stage cascode low noise amplifier (LNA) and an active down-conversion Rx mixer, and a transmit (Tx) chain composed of a Gilbert-Cell core up-conversion Tx mixer and a high-gain Driver Amplifier (DA). The high linear LNA shows a gain of 15.5 dB, an noise figure (NF) of 2.28 dB and an input- referred third-order intercept point (IP3) of +2.4 dBm with 1-dB gain bandwidth (BW) of 1.5 GHz. The single-balanced Rx mixer exhibited a gain and 1-dB gain BW of +6.8 dB and 1.5 GHz. Also a double-balanced Tx mixer with a gain and input/output return loss of -1.3dB and below -35dB, respectively, and a DA with a gain and output-referred IP3 of +29.2dB and +21.2dBm, respectively, is developed. The NF, input-referred IP3 and DC power consumption of Rx string (from antenna to Rx mixer) were achieved 4.4 dB, -15.4 dBm and 30 mW respectively. The output-referred IP3 and power consumption of Tx chain were +20.5 dBm and 125 mW, respectively

A 3-Mode Switched-Gain Low Noise Amplifier for Wireless Bands Applications Using an MMIC Technology

International audienceThis paper describes a 2.4 GHz single-ended switched gain low noise amplifier (SG-LNA) in a 0.35 mum SiGe BiCMOS process. In the design, specific architecture decisions were made in consideration of system-on-chip implementation. The architecture profits from a two cascode stage topology with a shunt resistive feedback in the first cascade-topology stage. The SG-LNA achieved a maximum small signal gain of 34.3 dB within input 1-dB compression point (ICP1dB) of -22 dBm in high-gain mode (HGM), a gain of 25.4 dB within ICP1dB of -13.8 dBm in medium-gain mode (MGM) , and a minimum gain of 18.3 dB within ICP1dB of -6.8 dBm in low-gain mode (LGM). The noise figures (NF) are 2.9 dB, 5.5 dB and 5.9 dB in HGM, MGM and LGM, respectively. Because of using a Common-Gate topology as an active input matching, the SG-LNA presented a good input and output return losses in all modes. All biases applied are active. The SG-LNA consumes a maximum DC current of 42 mA from a 3.3 volt DC supply