Drying of Iron Chloride Solutions: Laser Heating of Levitated Single Particles

Iron chloride solutions are a waste product from the steel industry, which has to be recovered by the so‐called spray roasting process. As this process is a complex sequence of different steps, the drying process of the droplets was separated to get deeper insight into the particle formation process from aqueous iron chloride solutions. Experiments were carried out on single droplets in an acoustic levitator. A CO₂ laser was used as heat source for the drying process. Particles with different shapes were generated by various concentrations of FeCl₂ and laser power. The characteristic time scales and particle size evolution are compared with literature data.     

Multi-focus image fusion for different datasets with super-resolution using gradient-based new fusion rule

Multimedia Tools and Applications - Multi-focus image fusion methods combine two or more images which have blurred and defocused parts to create an all-in-focused image. All-in-focused image has...     

Additive manufacturing of PA12 carbon nanotube composites with a novel laser polymer deposition process

The facile manufacture of PA12 MWCNT/silica (50/50 by weight) nanocomposite powders through a high energy mixing process is presented, which are useful to generate 3D objects by a novel Laser Polymer Deposition (LPD) process. The mixing as well as the LPD process led to no discernible changes in the material properties (DSC, SEM, LD) of the core-shell nanocomposites, enabling the recycling of unconverted powder. The built parts yield ultimate tensile stresses and Young's modulus at 10%–20% of the bulk material. Partially unmolten particles and voids were identified as the main mechanical failure mechanism in the built parts. The mechanical properties are better with low additive content (Young's modulus: 89.8 ± 5.4 MPa; UTS: 12.9 ± 5.3 MPa with 0.25 wt% additives). Electronic conductivity up to the region of moderate conductivity could be achieved by multiwalled carbon nanotube (MWCNT) network formation (8 × 10⁻⁴ S cm⁻¹ at 1.25 wt% of additives). A variant of the processing strategy revealed that a higher mechanical strength can be achieved by a laser induced remelting of the traces following their initial construction.     

Measurement of high electrical current density effects in solder joints

Measuring mechanical implications of high current densities in microelectronic packaging interconnects has always been a challenging goal. Due to small interconnect size this task has typically been accomplished by measuring the change in electrical resistance of the joint. This measurement parameter is global and does not give local mechanical state information. Also, understanding strain evolution in the solder over time is an important step toward developing a damage mechanics model.The real-time, full-field, strain displacement in a eutectic Sn/Pb solder joint during electrical current stressing was measured with Moiré interferometry (Post et al., High sensitivity Moire, Springer, New York, 1994) under in situ conditions. A finite element model simulation for thermal stressing was performed and compared with measured strain. The initial results show that the measured strain was largely due to thermal stressing versus the current density of 1.8 × 10² A/cm². A second Moiré interferometry experiment with thermal control distinguishes deformation of solder joint due to pure current stressing above 5000 A/cm².     

New hybrid active power filter for harmonic current suppression and reactive power compensation

In the case of undistorted and balanced grid voltages, low ratio shunt active power filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt APF. A new method for alleviating the negative effects of a nonideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field-programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance result of the proposed HAPF system is tested and presented under nonideal supply voltage conditions.     

Experimental and Numerical Modal Characterization for Additively Manufactured Triply Periodic Minimal Surface Lattice Structures: Comparison between Free-Size and Homogenization-Based Optimization Methods

Homogenization-based topology optimization (HMTO) is one of the most extensively used grading methods to generate functionally graded lattice structures (FGLs). However, it requires a precharacterization of the lattices, which is time-consuming. As a remedy, free-size optimization-based graded lattice generation (FOGLG) is explored as an alternative method to generate the FGLs. This article builds on the authors’ previous work in which the HMTO and FOGLG approaches are studied to improve the dynamic characteristic of a design by using a single lattice type, namely, double gyroid (DG) structure. To show applicability of the proposed methods, different lattice types including diamond (D), gyroid (G), and I-WP are employed to create FGLs herein. The frequency response analysis is performed, and the results from HMTO and FOGLG are compared in terms of their accuracy and efficiency. The optimized designs are then reconstructed by relative density mapping (RDM) and enhanced relative density mapping (ERDM) methods. The fabricated test samples made of cobalt–chromium using the direct metal laser melting (DMLM) technique are then experimentally validated using a laser vibrometer. The results reveal that HMTO and FOGLG can be used on the lattice types with a variety of configurations and relative densities.     

Line crack subject to antiplane shear

Field equations of nonlocal elasticity are solved to determine the state of stress in a plate with a line crack subject to a constant anti-plane shear. Contrary to the classical elasticity solution, it is found that no stress singularity is present at the crack tip. By equating the maximum shear stress that occurs at the crack tip to the shear stress that is necessary to break the atomic bonds, the critical value of the applied shear is obtained for the initiation of fracture. If the concept of the surface tension is used, one is able to calculate the cohesive stress for brittle materials.     

Inactivation Kinetics of Polyphenol Oxidase in an Aqueous Model System under Stand-Alone and Combined Ultrasound and Ultraviolet Treatments

The objectives of this work were to study the ultrasound- and ultraviolet light-induced inactivation kinetics of polyphenol oxidase extracted from different sources in a model system. The polyphenol oxidase crude extract was obtained from bananas, apples, quince, eggplants, plums, dill, and cultured mushrooms, which exhibited high enzyme activity. The polyphenol oxidase crude extract was treated with ultrasound and ultraviolet light at 40°C temperature for 40 min. The study showed that the polyphenol oxidase enzyme was inactivated between 12 and 100% during ultrasound only treatment; between 4 and 29% during ultraviolet light only treatment; and between 80 and 100% during simultaneous ultrasound and ultraviolet light treatment. Based on the measurements, an exponential decay model for determining polyphenol oxidase inactivation kinetics was developed. The model provides high determination coefficients (R²): 0.968–0.999 with ultrasound only treatment, 0.881–0.990 with ultraviolet only treatment, and 0.975–1.000 with simultaneous ultrasound and ultraviolet treatment. The polyphenol oxidase kinetics evaluation showed that different treatments provided different inactivation times, or D-values. The D-values were 7.0–656.1 min for ultrasound only treatment (D_US), 251–1887 min for ultraviolet only treatment (D_UV), and 3.3–59.4 min for combined ultrasound and ultraviolet treatment (D_US+UV).