Investigation of Control Method for Connected-Automated Vehicle to Multiplex Dedicated Bus Lane

Dedicated bus lanes (DBLs) have been widely utilized to ensure public transport priority. To improve overall road efficiency, various control methods of multiplexing DBL are developed and discussed. In this study, we focus on the control method which is based on the connected-automated vehicle (CAV) technology, and the proposed method is validated by using microscopic traffic simulation. The simulation results show that two proposed control methods of multiplexing DBL can reduce the average delay and the average number of stops and increase the travel speed. In comparison, the real-time control method based on the CAV technology offers better effects than the improved signal light control method.

All-Optical Switching In A Medium of A Four-Level Vee-Cascade Atomic Medium

We proposed a model for all-optical switching in a medium consisting of four-level vee-cascade atomic systems excited by coupling, probe, and signal fields. It is shown that, by changing the intensity or the frequency of the signal field, the medium can be actively switched between either electromagnetically induced transparency (EIT) or electromagnetically induced absorption (EIA), which has behavior of all-optical switching. As a result, a cw probe field is switched into square pulses by modulating the intensity or the frequency of the signal light. Furthermore, width of the square probe pulses can be controlled by tuning the switching period of the signal field. Such a tuneable all-optical switching is useful for finding related applications in optic communications and optical storage devices.

A Portable, Cost-Effective and User-Friendly Instrument for Colorimetric Enzyme-Linked Immunosorbent Assay and Rapid Detection of Aflatoxin B1

Food analysis based on the enzyme-linked immunosorbent assay (ELISA) is simple, sensitive and rapid, but requires a costly colorimetric instrument. The aim of this work was to develop a portable, low-cost and user-friendly colorimetric instrument for colorimetric ELISA and aflatoxin B1 (AFB1) detection. The principle of the developed instrument was employing a light-emitting diode to generate the signal light and using a light-dependent resistor to measure the signal light absorbed by the oxidized 3,3′,5,5′-tetramethyl benzidine. The absorption spectra revealed that the solution absorbed signal light more strongly after reaction with H2SO4, and blue light would be favorably absorbed. Evaluations on the stability and accuracy of the instrument and interference from ambient light showed that the fabricated instrument was stable, accurate, capable of quantitative detection and insensitive to ambient light changes. In addition, this instrument is user-friendly since it could calculate and report the final amount of AFB1 to the operator. Measurements of maize and peanuts showed that the instrument provided as accurate results as the professional equipment. With the low fabrication cost (about RMB 129 or USD 20), portability, and user-friendliness, this instrument presents attractive potential in the rapid detection of AFB1.

All-optical modulation based on MoS2-Plasmonic nanoslit hybrid structures

Two-dimensional (2D) materials with excellent optical properties and complementary metal-oxide-semiconductor (CMOS) compatibility have promising application prospects for developing highly efficient, small-scale all-optical modulators. However, due to the weak nonlinear light-material interaction, high power density and large contact area are usually required, resulting in low light modulation efficiency. In addition, the use of such large-band-gap materials limits the modulation wavelength. In this study, we propose an all-optical modulator integrated Si waveguide and single-layer MoS2 with a plasmonic nanoslit, wherein modulation and signal light beams are converted into plasmon through nanoslit confinement and together are strongly coupled to 2D MoS2. This enables MoS2 to absorb signal light with photon energies less than the bandgap, thereby achieving high-efficiency amplitude modulation at 1550 nm. As a result, the modulation efficiency of the device is up to 0.41 dB μm−1, and the effective size is only 9.7 µm. Compared with other 2D material-based all-optical modulators, this fabricated device exhibits excellent light modulation efficiency with a micron-level size, which is potential in small-scale optical modulators and chip-integration applications. Moreover, the MoS2-plasmonic nanoslit modulator also provides an opportunity for TMDs in the application of infrared optoelectronics.

New modeling approach of laser communication in constellation and through atmospheric disturbances

Laser communication between satellites in the constellation and from the satellites to ground stations offers a gigantic data rate for the users. This principal advantage drives telecom companies to develop this technology to use it like a carrier signal, the most disadvantage of this technology is the need to very complicated pointing systems between the transmitter and the receiver due to a very small beam divergence, continually moving of satellites in orbits and the distance between the satellites (tens of thousands of kilometers). The laser beam suffers continuously from several factors like atmospheric turbulences, internal and external vibrations. All these factors lead to an increase in the bit errors rate and cause degradation in the communication quality. This paper deals with a new method of modelisation of external effects in transmission of signal light from a ground station to the satellite through atmospheric disturbances. Indeed, an in-depth investigation, of the influences of satellite vibrationsinlaser signal transmission between satellites constellation, has been conducted by studying the effect of the intensity of vibrations on the optical signal amplitude. Some solutions are proposed to improve the efficiency of optical satellites communications.

The Virtual Lock-in Amplifiers - Accuracy of Measurement Results in Light Transmission Experiments

This research focuses on the analysis of the measurement result of the virtual lock-in amplifier (virtual-LIA) in the light transmission experiment as the trial step of developing the virtual-LIA. The virtual-LIA used in this research is designed by using the Vernier sensor DAQ as the data acquisition and the LabVIEW as the programming media. The design of virtual-LIA is based on the mathematical operations of LIA. The type of virtual-LIA is a single phase with the capabilities to process the external reference signal. Light transmission experiments are carried out using formazin polymer suspension with turbidity level of 3000 NTU, 3500 NTU, and 4000 NTU as the medium in which light is passed. The accuracy of the measurement results is known by comparing the results of virtual-LIA with real-LIA SR510. The experiments are also carried out in bright and darkroom conditions to determine the ability of virtual-LIA in reducing noise signals. Based on the experiment, the results obtained that the measurement accuracy of the virtual-LIA developed is above 94% compared to the LIA SR510. Virtual-LIA could measure small signals with and without noise with the average percentage of differences measured between dark and bright conditions is 0.54%.