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Polyvinylidene fluoride (PVDF) films have a great potential in soft flexible piezoelectric device development due to the organic nature and high piezoelectric response. To further improve PVDF’s piezoelectric properties, it is necessary to enrich the content of the electroactive phase. In this study, a method to achieve such goal is developed, which is composed of solvent casting, vacuum baking, and a homemade simplified corona poling platform. The experimental results show that the content of the electroactive phase of the PVDF film can be enriched up to 86.1% by optimizing the vacuum baking temperature and poling parameters. In addition, the piezoelectric coefficient (d 33) of the poled PVDF film with an absolute value of 16.4 pC·N–1 is achieved. Furthermore, the output piezoelectric voltage and current density of the PVDF film generator can reach ∼2.1 V and ∼240 nA·cm–2, respectively. To further enhance the output performance, 0.5 wt % TiO2 nanoparticles is doped into the PVDF solution, and the output voltage and current density of the generator based on a PVDF-TiO2 composite film are ∼3.5 V and ∼400 nA·cm–2, respectively, which can light up a red LED. Therefore, the method developed in this study made it possible to fabricate a PVDF-based generator in a large scale and has a potential application in a self-powered system.

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In this paper, numerical analysis of GaSb (E g = 0.72 eV)/Ga 0.84 In 0.16 As 0.14 Sb 0.86 (E g = 0.53 eV) tandem thermophotovoltaic (TPV) cells is carried out by using Silvaco/Atlas software. In the tandem cells, a GaSb p-n homojunction is used for the top cell and a GaInAsSb p-n homojunction for the bottom cell. A heavily doped GaSb tunnel junction connects the two sub-cells together. The simulations are carried out at a radiator temperature of 2000 K and a cell temperature of 300 K. The radiation photons are injected from the top of the tandem cells. Key properties of the single-and dual-junction TPV cells, including I-V characteristic, maximum output power (P max), open-circuit voltage (V oc), short-circuit current (I sc), etc. are presented. The effects of the sub-cell thickness and carrier concentration on the key properties of tandem cells are investigated. A comparison of the dual-TPV cells with GaSb and GaInAsSb single junction cells shows that the P max of tandem cells is almost twice as great as that of the single-junction cells.

The intelligent transportation system (ITS) is inseparable from people’s lives, and the development of artificial intelligence has made intelligent video surveillance systems more widely used. In practical traffic scenarios, the detection and tracking of vehicle targets is an important core aspect of intelligent surveillance systems and has become a hot topic of research today. However, in practical applications, there is a wide variety of targets and often interference factors such as occlusion, while a single sensor is unable to collect a wealth of information. In this paper, we propose an improved data matching method to fuse the video information obtained from the camera with the millimetre-wave radar information for the alignment and correlation of multi-target data in the spatial dimension, in order to address the problem of poor recognition alignment caused by mutual occlusion between vehicles and external environmental disturbances in intelligent transportation systems. The spatio-temporal alignment of the two sensors is first performed to determine the conversion relationship between the radar and pixel coordinate systems, and the calibration on the timeline is performed by Lagrangian interpolation. An improved Hausdorff distance matching algorithm is proposed for the data dimension to calculate the similarity between the data collected by the two sensors, to determine whether they are state descriptions of the same target, and to match the data with high similarity to delineate the region of interest (ROI) for target vehicle detection.

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