Background. Most documented "superspreading events" of severe acute respiratory syndrome (SARS) occurred in hospitals, but the underlying causes remain unclear. We systematically analyzed risk factors for nosocomial outbreaks SARS among hospital wards Guangzhou and Hong Kong, China.

A novel hybrid time-frequency domain equalization scheme is proposed and experimentally demonstrated to mitigate the white light emitting diode (LED) nonlinearity in visible communication (VLC) systems based on orthogonal frequency division multiplexing (OFDM). We handle linear nonlinear distortion separately a OFDM system. The part equalized compensated by an adaptive time equalizer (N-TDE). experimental results show that with only small number of parameters can efficiently LED...

The Q-learning based geographic routing approaches suffer from problems of low converging speed and inefficient resources utilization in VANET due to the dynamic scale Q-value table. In addition, next hop selection on local information can not always be conducive global message forwarding. this letter, we propose an adaptive unmanned aerial vehicle (UAV) assisted with Q-Learning. scheme is divided into two components. component, path calculated by fuzzy-logic depth-first-search (DFS)...

Inherent multipath diffuse channel characteristics inhibit visible light communications (VLC) system to provide uniform and satisfactory communication performance within the room domain. An evolutionary algorithm based optimization scheme is proposed modify optical intensity of LED transmitters for reducing signal power fluctuation extent. Simulation results show that can efficiently reduce dynamic range up 26.5% while SNR still sufficient keeping BER<;10 <sup...

Free-space optics (FSO) and visible light communication (VLC) share the same optical wireless features, such as high data rate, license free, energy efficient, flexible access, degree of security. A hybrid network based on FSO/VLC heterogeneous interconnection is presented here for future space-air-ground-ocean-integrated architecture, especially in radio-frequency-sensitive (RF) or security-required environments. The functional modules coordinator are defined, along with implementation...

Non-orthogonal multiple access (NOMA) has recently attracted significant attention as a promising scheme for the 5th generation (5G) wireless communication due to its superior spectral efficiency, which also been studied and shown achieve performance in visible light (VLC) networks. However, error propagation (EP) problem successive interference cancellation (SIC) decoding not yet resolved, degrades system BER causes user unfairness. In this work, symmetric superposition coding (SSC) SIC...

Most existing studies on connected and automated vehicle (CAV) applications apply simulation to evaluate system effectiveness. Model accuracy, limited data for calibration, assumptions limit the validity of evaluation results. One alternative approach is use emerging hardware-in-the-loop (HIL) testing methods. HIL test environments enable physical vehicles interact with virtual from traffic models, providing an environment that can replicate deployment conditions at early stages CAV...

Abstract This study proposes a mixed traffic simulation framework that integrates vehicle car‐following (CF) and lane‐changing (LC) with connected automated vehicles (CAVs) of different cooperation behaviors. is centered at CAV LC model incorporated CF dynamics in traffic. The was calibrated validated using data collected from small‐scale field experiments previous study. To demonstrate large‐scale application this framework, PTV Vissim used to implement the on segment Interstate 75 highway....

We propose and experimentally demonstrate a novel modulation scheme called superposed pulse amplitude (SPAM) which is low-cost, insensitive to non-linearity of light emitting diode (LED). Multiple optical pulses transmit parallelly from different spatial position in the LED array overlap linearly free space realize SPAM. With arrangement, experimental results show that using we proposed data rate 120 Mbit/s with BER 1 × 10(-3) can be achieved an blue filter RC post-equalization.

The purpose of this study is to define an operational concept involving connected automated vehicle (CAV) operation on freeway managed lanes. Despite the low projected market penetration CAVs during next decade, use lane facilities has potential support realization increased mobility benefits by their very nature. proposed CAV involves platoons equipped vehicles governed integrated applications, including cooperative adaptive cruise control (CACC), merge, and speed harmonization. This...

Recently, a hybrid multiple access (MA) scheme, non-orthogonal MA (NOMA) combined with orthogonal frequency-division (OFDMA), has attracted significant attention in the fifth-generation (5G) wireless communication due to its superior spectrum efficiency. However, advantage of scheme cannot be fully realized visible light (VLC) networks, since current optical multiplexing (OFDM) technologies are unable provide high efficiency and power at same time. In this paper, hierarchical pre-distorted...

Cooperative adaptive cruise control (CACC) organizes connected and automated vehicles (CAVs) in platoons to improve traffic flow reduce fuel consumption. Platoon formation involves a very complex process, however, because lateral longitudinal misbehavior of CAVs results greater consumption risk collision. This study aims design optimal vehicle trajectories during CACC platoon formation. First, basic scenario destination-based protocol are described determine sequence the platoon. A...

Connected-and-automated vehicles (CAV) hold the potential for substantial improvements to traffic safety, travel time reliability, driver comfort, roadway capacity, environmental impacts, and users' overall experience. Numerous modeling simulation studies have been conducted evaluate these impacts. However, model accuracy assumptions limit validity of evaluation results. These factors resulted in wide range differences effectiveness among examining same CAV applications available literature....

Understanding the effect of ocean turbulence on optical beam propagation is critical to design and performance evaluation underwater wireless communication systems. In this Letter, we propose a unified Weibull-generalized gamma distribution characterize laser irradiance fluctuations turbulent thermocline channels. The proposed model shows an excellent agreement with measured data under various experimental emulated channel conditions that cover turbulences induced by temperature, salinity,...

Due to the presence of bad weather conditions, images captured in outdoor environments are usually degraded. In this paper, a novel single image dehazing method is proposed enhance visibility such degraded images. Since property haze widely spread, estimated transmission should be smoothly changed over scene. The fast wavelet transform (FWT) introduced estimate smooth our work. To preserve more details and correct color distortion, solution based on weighted fusion strategy provided....

Connected and automated vehicles (CAVs) are poised to transform how we manage control the existing traffic. CAVs can provide accurate distance sensing adaptive cruise which make shorter headway possible, will eventually increase roadway throughput or capacity. The vehicle-to-vehicle (V2V) communication technology equipment on allows exchange information form platoons more efficiently. This paper uses intelligent driver model (IDM) as behavior simulate in mixed traffic conditions with both...

Most existing studies on connected and automated vehicle (CAV) applications apply simulation to evaluate system effectiveness. Model accuracy, limited data for calibration, assumptions limit the validity of evaluation results. One alternative approach is use emerging hardware-in-the-loop (HIL) testing methods that allow physical test vehicles interact with virtual from traffic models. This provides an environment can replicate deployment conditions at early stages CAV implementation -...

In this paper, an evolutionary algorithm based optimization scheme is proposed to realize uniform received power and illumination distribution on the communication floor for fully diffuse indoor visible light communication. Simulation results show that in three distributed lighting configurations, by dynamically modifying relative optical intensity of transmitters dynamic range power, referenced against peak can be reduced about 40.0% while uniformity illuminance ratio improved up 0.70 with...