Microwave Heating of Cordierite Ceramic Substrate for After Treatment Systems

Selective catalyst reduction is one of the most affordable and successful technologies aimed at reducing NOx emissions from diesel engines. However, the reduction process can be achieved if a certain temperature is reached for the ceramic substrate of the catalytic core. The required temperatures for catalytic reaction vary from 2500 C to 4500 C depending on the technology applied in the catalytic processes. This paper aims at presenting preliminary research in microwave cordierite heating, which is a type of magnesium aluminium silicate used as ceramic honeycomb substrate (catalyst monolith) in the after treatment system in the automotive industry. The research focused on testing the Mg2Al4Si5O18 composite material (cordierite) for different microwave heating regimes in order to establish the level of microwave power required for fast heating. This application will be subject for the further development of new MW-SCR after treatment systems in order to reduce the NOx emissions at cold start engine or low operating regimes of non-road mobile machinery engines. The ceramic composite material was heated for 5 levels of microwave power, from 600 W to 1400 W, using a 6 kW microwave generator coupled with a matching load impedance tuner, and the temperatures were recorded using an IR pyrometer.

Nanoscale mechanical properties of 3D printed gypsum-powder-based rocks by nanoindentation and numerical modeling

Purpose Evaluating mechanical properties of simply made samples by 3D printing technology at nanoscale provides a clear path to better understand larger-scale responses of complex natural rocks. Therefore, to realize the similarity between synthetically manufactured materials and natural geomaterials, this study focused on nanoscale mechanical characterization of a 3D printed object with only two constituent components (gypsum powder and infiltrant). Design/methodology/approach The study method includes nanoindentation technique combined with numerical simulation via discrete element method (DEM). Findings Four typical load-displacement curves were identified from nanoindentation of total test points indicating a typical elastic-plastic behavior of the 3D printed gypsum rock sample. Mechanical parameters such as Young’s modulus and hardness were calculated by energy-based methods and a positive correlation was observed. The infiltrant was found to considerably be responsible for the majority of the sample nano-mechanical behavior rather than the gypsum particles, thus expected to control macroscale properties. This was decided from deconvolution and clustering of elastic modulus data. Particle flow modeling in DEM was used to simulate the nanoindentation process in a porous media yielding rock-alike mechanical behavior. Originality/value The results show a matching load-displacement response between experimental and simulation results, which verified the credibility of simulation modeling for mechanical behavior of 3D printed gypsum rock at nanoscale. Finally, differential effective medium theory was used to upscale the nanoindentation results to the macroscale mechanical properties, which provided an insight into the geomechanical modeling at multiscale.

High Efficiency Harmonic Harvester Rectenna for Energy Storage Application

This work presents harmonic harvester Rectenna integrated power management circuitry for improving RF-DC power conversion efficiency. The circuitry is developed for battery charging or energy storage application; resistance emulation method is used to realize a matching load resistance at output terminals. The proposed technique is useful for harvesting near maximum output power from the dual rectifiers (fundamental and harmonics) independently. Also, it delivers the combined maximal power to the energy storage cell. The power management module based on dual input buck-boost converter with simple open loop control is utilized.

Optimization of energy harvesting based on the uniform deformation of piezoelectric ceramic

Since the piezoelectric properties were used for energy harvesting, almost all forms of energy harvester needs to be bonded with a mass block to achieve pre-stress. In this article, disc type piezoelectric energy harvester is chosen as the research object and the relationship between mass bonding area and power output is studied. It is found that if the bonding area is changed as curved, which is usually complanate in previous studies, the deformation of the circular piezoelectric ceramic is more uniform and the power output is enhanced. In order to test the change of the deformation, we spray several homocentric annular electrodes on the surface of a piece of bare piezoelectric ceramic and the output of each electrode is tested. Through this optimization method, the power output is enhanced to more than 11[Formula: see text]mW for a matching load about 24[Formula: see text]k[Formula: see text] and a tip mass of 30[Formula: see text]g at its resonant frequency of 139[Formula: see text]Hz.

Thermoelectric Properties and Power Generation of p–Ca3Co4O9 and n–Sr0.87La0.13TiO3 Thermoelectric Modules

The Ca3Co4O9 (CCO) and Sr0.87La0.13TiO3 (SLTO) are good property of oxide thermoelectric (TE) materials. They synthesized by solid state reaction (SSR) method to study thermoelectric properties and fabrication of thermoelectric module. It was found that, synthesis of CCO shows that Seebeck coefficient, electrical resistivity, thermal conductivity and values are 130 μV K–1, 8.31 mΩ cm, 0.82 W m–1 K–1 and 0.08, respectively at 473 K. The Seebeck coefficient, electrical resistivity, thermal conductivity and ZT values of SLTO are –359 μV K–1, 2.9 mΩ m, 18.09 W m–1 K–1 and 1.13×10–3, respectively at 473 K. TE modules of CCO and SLTO were fabricated by ultra sonic soldering method. The power generation of TE modules were measured with temperature difference (ΔT) of 10–180 K. The 1 pair and 2 pairs TE modules for a maximum power generation of matching load are 19 k and 30 k, respectively. The maximum output power of 2 pairs TE module is larger than 1 pair TE module about two times.

A Broadband Single-Feed Circularly Polarized Patch Antenna with Wide Beamwidth

A broadband single-feed circularly polarized patch antenna with wide beamwidth is presented. The patch is coupled to four asymmetric cross slots via a microstrip ring with eight matching segments underneath the ground plane, traversing through the arms of the cross slots in a serial manner. And a coupling slice instead of a resistive load is used as matching load of the microstrip ring for higher gain. Furthermore, a metal side wall surrounding the antenna is used to improve the isolation between adjacent elements in an array. Through optimizing the four asymmetric cross slots and eight matching segments, excellent performances are achieved by the proposed antenna, especially for the broadband and wide beamwidth. Measurement results show that the antenna has −10 dB reflection coefficient bandwidth of 29.7%, 3-dB axial-ratio bandwidth of 21.6%, and beamwidth of more than 90°. It can be considered as a good candidate for the element of arrays.

Complex Impedance Matching for Power Improvement of a Circular Piezoelectric Energy Harvester

The impedance matching and the optimization of power from a circular piezoelectric energy harvester with a central-attached mass are studied. A finite element model is constructed to analyze the electrical equivalent impedance of the circular piezoelectric energy harvester. Furthermore, the complex conjugate matching load is used to extract the maximum output power of the energy harvester. The power output from complex conjugate matching load is compared with the power output from the resistive matching load and a constant resistance, separately. The results suggest that the complex conjugate matching can result in a significant increase of the output power for all frequencies. The effective bandwidth of the piezoelectric energy harvester is extended significantly.

Microwave Power Real-Time Soft-Measuring Based on Improved BP Neural Network

There are many faults in microwave power measurement in the working spots. In this paper, the novel technique of microwave power measurement and Schottky detector and the technique of soft-measuring based on improved BP neural network are presented. Making use of directional coupler, the part of power of microwave signal in transmission line was taken in the certain proportion. Then, the microwave power meter indicated the magnitude of power. The microwave power measurement system was composed of tuneable attenuator, directional coupler, matching load, peak-peak value detector, oscillograph, thermocouple, soft-measuring algorithm and so on. The low microwave power meter obtained the sample data of training BP neuron network. Then, the output of trained BP neural network may represent the result of high microwave power measurement. The experiments and applications in practice project prove that this new method has many advantages.

Micro-Rotational Generator

Energy harvesting is a relatively new research area that extracts energy from the surroundings to power autonomous systems. This project presents a generator that harnesses the motion of high speed rotational motors for machine health monitoring. Wireless accelerometer-based sensors for detecting crack initiation on rotating shafts are typically limited by the battery finite lifetime. Miniature generators attached to rotating shafts can scavenge small amounts of energy for powering such monitoring systems. Electromagnetic induction approaches (using coils and magnets) have been widely described in literature for larger machines but few at the micro-scale. This paper investigates a multiple-pole permanent magnet design with multiple-stacks of planar coils for energy generation without using Silicon-based processing at the micro-scale. Planar coils are manufactured from 18μm thick Copper-clad on 25μm thick polyimide. The 25mm diameter coils were stacked and bonded with cyanoacrylate for a stacked thickness of 360μm. The rotor was made of a 25mm in diameter (2mm thick) CNC machined PMMA disk with 20 slots (1mm×2mm×6mm) for placing commercial NdFeB permanent magnets. The entire generator had a volume smaller than 1.5cm3. Experimental results show that the generator is capable of producing an average voltage output of 15.5V and 727mW of power (with a matching load) at a constant rotational speed of 29,500rpm.