Flat OFC Generation Based on DPMZM Cascaded Dual-Parallel PolM with Frequency Multiplication Circuit

An innovative scheme to generate the high-quality OFC based on DPMZM cascaded dual-parallel PolM with frequency multiplication circuit is proposed and demonstrated. In the scheme, 5 comb lines are generated in the first-stage generator, and the comb line is expanded to 11 times in the second-stage generator. The theoretical model of the overall scheme is established and analyzed. In this scheme, 66-line OFC is generated and the flatness is 0.73 dB, the side mode suppression ratio (SMSR) is 14.19 dB, and the optical signal noise ratio (OSNR) is about 29 dB.

Flexible, scalable, and efficient thermoelectric touch detector based on PDMS and Graphite flakes

This paper presents freestanding thermoelectric touch detectors consisting of graphite conductive flakes into a polydimethylsiloxane matrix. An optimal concentration of graphite flakes (45 wt%) lead to robust and homogeneous detectors that exhibited signal-noise ratio values up to 170 with rise and falling times below 1 s and 7 s, respectively. The detectors performance was stable over continuous operation and did not reveal significant degradation while bended under different curvature radii (45, 25 and 15 mm) and consecutive bending cycles. Moreover, the twist of the thermal gradient direction between the electrodes of the detector enables a Yes or No response which opens new usage possibilities. Therefore, this work provides an efficient way to develop robust, low-cost, and scalable thermal detectors with potential use in wearable technologies.

A free-geometry geodynamic modelling of surface gravity changes using Growth-dg software

Globally there is abundant terrestrial surface gravity data used to study the time variation of gravity related to subsurface mass and density changes in different geological, geodynamical and geotechnical environments. We present here a tool for analysing existing and newly acquired, 4D gravity data, which creates new findings from its reuse. Our method calculates in an almost automatic way the possible sources of density change responsible for the observed gravity variations. The specifics of the new methodology are: use of a low number of observation points, relatively small source structures, low signal/noise ratio in the data, and a free 3D source geometry without initial hypothesis. The process is based on the non-linear adjustment of structures defined by aggregation of small cells corresponding to a 3D section of the sub-floor volume. This methodology is implemented in a software tool, named GROWTH-dg, which can be freely downloaded for immediate use, together with a user manual and application examples.

The influence of signal noise to measurements at bridge structure

Bridge weight-in-motion (BWIM) system is a method, that provides to identify axle weights. It is a non-destructive method, which allows not only to identify the axle weight, but it can show current shape of the structure, so it has a great potential. There are various methods to do measurements for this system. Mostly, accelerometers or strain gauge are used. Signal noise has significant effects to the results. It could be resonance of the bridge, wind, defect at the support system, defect at the roadway, etc. It is necessary to filter all this effects, to get clear data. There are many ways to do the filtering. Digital filters allow it. Sometimes, this type of filtering could remove important data about the crossing of the vehicle. It could generate inaccuracy of the whole system and create major errors to identified vehicles. It is necessary to find the optimal way, to keep important data and remove all dynamic noise. This paper will investigate the previously mentioned problems. Measurements will be accomplished on a small-scale model of the bridge. Vehicle will be crossing over the bridge, while the bridge will be awakened to the first vibration shape and other frequencies, that will have a great impact to the measurements.

System modeling and control system performance optimization of magnetic suspension and balance system

A magnetic suspension and balance system (MSBS) is a kind of aerodynamic test equipment for aircraft. It uses levitation control technology to replace the mechanical support and strain measurement technology in traditional wind tunnel balance. It has the advantage of no model support to interfere with the wind tunnel flow field and make the test environment more realistic, but the MSBS has technical difficulties to be solved. It is difficult to control and stabilize because it has a large suspension gap, nonlinear magnetic field, a long-acting distance of magnetic force, and uses a visual sensor to feedback the position of the controlled object that it has signal noise. At present, there are few studies on the suspension control method and suspension performance of MSBS. In this paper, in order to solve the above technical difficulties, the vertical control of the MSBS is taken as the research object, the electromagnetic field of the vertical coil is modeled and analyzed. A new control algorithm based on a fast-tracking differentiator (FTD) is proposed to solve the signal noise problem in MSBS. The influence of various factors in the control link on the suspension system is analyzed, and its optimization is carried out to improve the performance of the suspension system.

Small Object Signal Formation Model for Optical System with Matrix Photodetector When Processed by the Laplace Operator

The authors review the formation of a small object signal by an optical system with a matrix photodetector. They develop a mathematical model of signal formation and test it. The authors calculate the signal/noise proportion for various small object signal shapes and amplitudes processed by the Laplace operator.