Three-Dimensional Printing Quality Inspection Based on Transfer Learning with Convolutional Neural Networks.

Fused deposition modeling (FDM) is a form of additive manufacturing where three-dimensional (3D) models are created by depositing melted thermoplastic polymer filaments in layers. Although FDM is a mature process, defects can occur during printing. Therefore, an image-based quality inspection method for 3D-printed objects of varying geometries was developed in this study. Transfer learning with pretrained models, which were used as feature extractors, was combined with ensemble learning, and the resulting model combinations were used to inspect the quality of FDM-printed objects. Model combinations with VGG16 and VGG19 had the highest accuracy in most situations. Furthermore, the classification accuracies of these model combinations were not significantly affected by differences in color. In summary, the combination of transfer learning with ensemble learning is an effective method for inspecting the quality of 3D-printed objects. It reduces time and material wastage and improves 3D printing quality.

Real-time adaptive ultrashort pulse compressor for dynamic group delay dispersion compensation.

The optical dispersion effect in ultrafast pulse laser systems broadens the laser pulse duration and reduces the theoretical peak power. The present study proposes an adaptive ultrashort pulse compressor for compensating the optical dispersion using a direct optical-dispersion estimation by spectrogram (DOES) method. The DOES has fast and accurate computation time which is suitable for real time controller design. In the proposed approach, the group delay dispersion (GDD) and its polarity are estimated directly from the delay marginal of the trace obtained from a single-shot frequency-resolved optical gating (FROG). The estimated GDD is then processed by a closed-loop controller, which generates a command signal to drive a linear deformable mirror as required to achieve the desired laser pulse compression. The dispersion analysis, control computation, and deformable mirror control processes are implemented on a single field programmable gate array (FPGA). It is shown that the DOES dispersion computation process requires just 0.5 ms to complete. Moreover, the proposed pulse compressor compensates for both static dispersion and dynamic dispersion within five time steps when closed-loop controller is performed at a frequency of 100 Hz. The experimental results show that the proposed pulse compressor yields an effective fluorescence intensity improvement in a multiphoton excited fluorescence microscope (MPEFM).

Importing Automated Management System to Improve the Process Efficiency of Dental Laboratories.

Dental laboratories require manpower resources for manufacturing prostheses and inventory management. In this paper, we developed an automated inventory management system for dental laboratories to improve the production efficiency. A sensing system was developed based on the framework of Internet of things to collect the information of cobalt-chromium disks both in the storage room and manufacturing area, and an expert system was developed to automatically conduct inventory management based on the established rules. The proposed system can reduce the time of recording data and also assist the manager in configuring and managing material orders. The experimental results showed that a large amount of working time is reduced, resulting in the benefits of saving money and improving efficiency in dental manufacturing.

Perspective of material evolution Induced by sinusoidal reflex charging in lithium-ion batteries.

Background: Lithium-ion batteries are globally prominent and extensively employed alternative energy sources with decisive applications. In depth understanding of influences of various charging and discharging cycles on electrode materials and life span of these batteries is critical as cycle-life and safety of lithium-ion batteries are closely related crystallinity of electrode materials. This study is a detailed investigation endeavor in observing the degree of damage to electrode materials under multiple charging and discharging cycles. Method: ology: A constant current-sinusoidal reflex charging method (CC-Sinusoidal) was implemented to charge commercial cathode Lithium cobalt oxide (LiCoO2) electrodes and anode graphite electrodes in comparison to the conventional charging method of constant current-constant voltage (CC-CV). After 100, 300, and 500 cycles of charging and discharging, EIS, SEM, XRD, and Raman spectroscopies were used to compare the degree of electrode damage caused by different charging methods. Significant outcomes: The structure of positive LiCoO2 electrode of the battery was observed to be stable, with no significant change in both the charging methods after 500 cycles. The use of CC-CV charging method had caused severe damages to graphite electrode with generation of solid electrolyte interface (SEI) films. The CC-Sinusoidal charging method had maintained the electrode material in a relatively ideal state.

Electrochemical polarization analysis for optimization of external operation parameters in zinc fuel cells.

Zinc-air flow fuel cells utilizing zinc particles as fuel possess the potential to evolve as efficient distributed grid generators. In this research study, electrochemical impedance analysis was employed to determine the optimum design and operational parameters for the feasible maneuver and enhanced energy generation from zinc fuel cells. Polarization resistance (R p), ohmic resistance (R s), and mass transfer resistance (R m) were used as the indicators for determination of the optimum parameters of fuel cell performance. Experimental conditions optimized from previous studies like potassium hydroxide electrolyte with temperature of 25 °C and concentration of 40 wt% zinc powder quantity of 20 g, electrode reaction surface area of 48 cm2 were followed in the fuel cells used in the present study. Parameters like collector plate material, air flow velocity and cell operating temperature were augmented and finally were all implemented in the fuel cell and operated. Plain nickel or nickel-plated copper were both advantageous as collector plate materials whereas an air flow velocity ranging from 1-3 m s-1 and a cell operating temperature of 25 °C to 45 °C were beneficial for the stability and performance of the zinc fuel cells. Finally, based on the optimized parameters obtained from the above experiments, performance tests of zinc fuel cells were investigated. The maximum power produced was 16.5 W, along with a corresponding voltage of 0.8 V, maximum current density of 430 mA cm-2 and peak power density of 364.6 mW cm-2. Thus it can be concluded that the fuel cells designed and operated in this study were capable for feasible and efficient future applications.