No abstract

tapping-mode fluid delivery, [11] etc. To date, most inductors fabricated using additive manufacturing methods have been of the planar-spiral geometry. [12][13][14][15][16][17] A very interesting variant of the problem was carried out by Jing et al., who reported a stretchable induction coil printed by liquid gallium-indium (Ga-In) alloy ink. [17,18] Recently, printed air core toroidal and solenoidal inductors have also been demonstrated. [10] While some approaches do ensure inductor operation at a high frequency range (tens of GHz), they are invariably limited in that the inductance values generally in the nanohenry (nH) range have been demonstrated. Another limitation related to most (to-date) printed inductors is associated to the inverse relationship between the operating frequency and the inductance. [19,20] Therefore, it is desirable to develop direct-write printing methods that can be used to fabricate small size (<20 mm 3 ), microhenry (µH) to millihenry (mH) inductors that can operate at high frequencies.Toward this end, in this paper, we describe a novel directwrite 3D printing method for fabricating solid-core (polymercore, iron-core, and ferrite-core) inductors that demonstrate inductance values ranging from µH to mH and operate at frequency ranges of several kHz to MHz. We employ aerosol jet 3D printing (AJP), with a precisely controlled aerosol ink-stream deposition rate [21] for the fabrication. AJP is used to print both the polymer core (using an ultraviolet curable polymer ink) and the conducting windings (using a Ag nanoparticle ink) of the solid-core inductors. On the other hand, for the iron-core and ferrite-core solenoids, where the conducting windings are aerosol jet 3D printed, the core materials were pick-and-placed as needed with the UV curable polymer printed as a surface layer for electrical isolation and to ensure continuous, well-formed windings. Of course, for all three types of cores, we employ our developed technique of 3D printed interconnects-overfillets [22] to achieve the needed seamless electrical interconnection required for the printed inductor windings. Through this approach, in addition to realizing printed inductors with commercially relevant inductances, we successfully achieve a solenoid-inductor that has substrate area coverage of 20-30 mm 2 , a cross-sectional area of 2 mm 2 and a winding pitch (center-tocenter distance of adjacent inductor trace windings) of 150 µm. The significance of achieving such 3D printed inductors with commercially relevant inductances is in the ability to a) design and print such inductors directly as a part of the circuitry and in any position that improves the functional density of the Additive manufacturing has the potential to fabricate passive components (e.g., capacitors, resistors, inductors, etc.) of a radio frequency (RF) circuit with minimized dimensions and controllable shapes in order to realize high-density RF electronics for applications such as high resolution radars, healthcare monitors, and wearable sensors that involve high ...

This paper proposes a self-calibration method that can be applied for multiple larger field-of-view (FOV) camera models on an advanced driver-assistance system (ADAS). Firstly, the proposed method performs a series of pre-processing steps such as edge detection, length thresholding, and edge grouping for the segregation of robust line candidates from the pool of initial distortion line segments. A novel straightness cost constraint with a cross-entropy loss was imposed on the selected line candidates, thereby exploiting that novel loss to optimize the lens-distortion parameters using the Levenberg–Marquardt (LM) optimization approach. The best-fit distortion parameters are used for the undistortion of an image frame, thereby employing various high-end vision-based tasks on the distortion-rectified frame. In this study, an investigation was carried out on experimental approaches such as parameter sharing between multiple camera systems and model-specific empirical γ -residual rectification factor. The quantitative comparisons were carried out between the proposed method and traditional OpenCV method as well as contemporary state-of-the-art self-calibration techniques on KITTI dataset with synthetically generated distortion ranges. Famous image consistency metrics such as peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), and position error in salient points estimation were employed for the performance evaluations. Finally, for a better performance validation of the proposed system on a real-time ADAS platform, a pragmatic approach of qualitative analysis has been conducted through streamlining high-end vision-based tasks such as object detection, localization, and mapping, and auto-parking on undistorted frames.

Design, wind tunnel test, computational fluid dynamics (CFD) analysis, and flight test data analysis are conducted for the propeller of EAV-3, which is a solar-powered high-altitude long-endurance unmanned aerial vehicle developed by Korea Aerospace Research Institute. The blade element momentum theory, in conjunction with minimum induced loss, is used as a basic design method. Airfoil data are obtained from CFD analysis, which takes into account the low Reynolds number effect. The response surface is evaluated for design variables by using design of experiment and kriging metamodel. The optimization is based on desirability function. A wind tunnel test is conducted on the designed propeller. Numerical analyses are performed by using a commercial CFD code, and results are compared with those obtained from the design code and wind tunnel test data. Flight test data are analyzed based on several approximations and assumptions. The propeller performance is in good agreement with the numerical and measurement data in terms of tendency and behavior. The comparison of data confirms that the design method, wind tunnel test, and CFD analysis used in this study are practically useful and valid for the development of a high-altitude propeller.

No abstract