1,721,038 research outputs found
Solar thermal reactor model for pyrolysis of waste plastic
No full textThe ability to convert waste plastic into combustible liquids and gases using solar energy could help transform the problem of disposal of non-recyclable plastic into a valuable and environmentally responsible source of fuel. The purpose of this study is to propose a practical model for a compound parabolic trough solar thermal reactor for pyrolysis of waste plastic. The model integrates predictions of energy available from solar radiation (at a given location, time of day and time of year) with parabolic trough collector orientation and efficiency, a transient energy balance for an evacuated tube reactor and pyrolysis kinetics of waste plastic. The experimental setup used to test the model includes a pyranometer, a commercial solar collector consisting of a 60 cm long evacuated tube with a compound parabolic reflector and multi-channel data loggers to collect temperature, humidity and radiation data. The solar radiation sub-model was found to be in excellent agreement with clear-sky irradiance data collected using the pyranometer. Predictions of reactor temperature and reaction rate were found to be sensitive to the concentrator aperture area, solar irradiance, type of plastic (Arrhenius kinetics) and radiation properties of the evacuated tube reactor but relatively insensitive to humidity, wind velocity and terrestrial irradiance. The model shows that even on a small scale, favourable conditions for pyrolysis of waste plastic can be achieved within a solar reactor.Full Tex
A Single-Axis Vortex Gyroscope using built-in PZT Micropump
No full textThis paper presents the development of a single-axis gyroscope that uses vortex flows circulating in a confined space activated by a built-in PZT micropump. In this sensor, the deflection of the vortex flow is used as an inertial reference movement to find the angular rate by hotwire anemometry. The vortex gyroscope structure, composed of a pump chamber and rectifying nozzles, generates a net flow to the vortex chamber and then back towards the rectified nozzle for new circulation. After each vibration cycle of the PZT diaphragm, the circulating flow gets stronger to shape a vortex in the vortex flow chamber. Several hotwires are embedded in the vortex chamber for angular rate detection. The experimental result of the gyroscope on the turntable shows that the measured sensitivity for z-axis is about 13.6μV/°/s. Several parameters affect the sensor’s performance such as the driving voltage on the PZT diaphragm, the heating current of hotwire, and the effect of the linear acceleration are also analyzed and evaluated. Since the structure does not carry any solid-state displacement component nor use the external pump, the present gyroscope is robust.Full Tex
Piezo-pyro-phototronics: A propitious pathway for ultrasensitive sensing and self-power applications
No full textThe integration of piezo-phototronic and pyro-phototronic effects present a promising approach to enhance the performance of modern self-powered and ultrasensitive sensing systems. Thus, the multi-effect coupling of piezo-pyro-phototronics has emerged as a transformative platform, enabling significant advancements in ultrasensitive opto-electronic sensing, energy harvesting, and bio-inspired applications. These advancements are driven by distinctive facile and cost-effective manufacturing approaches, rapid response, reduced unwanted noises, and lower power consumption. In opto-electronic systems, the generation of piezoelectric charges and changes of electronic properties at the heterointerface under the piezo-phototronic effect modulate the generation, separation, drift, and recombination of the photogenerated charge carriers. Differently, the pyro-phototronic effect is a thermo-responsive phenomenon driven by the temperature fluctuations in a material under the action of pulsed irradiation, enhancing the innate pyroelectric polarization characteristics. Therefore, harnessing the potential of piezo-pyro-phototronics will significantly boost output photovoltage and photocurrent in semiconductor heterojunction devices. This review provides a comprehensive overview of the underlying physics of piezo-phototronic and pyro-phototronic effects, and their state-of-the-art advancements in sensing, energy harvesting, and bio-medical applications. Additionally, it highlights the challenges and offers insightful perspectives to guide the scientific community toward future innovations in self-powered optoelectronic and sensing devices.Full Tex
Numerical Study of Electrohydrodynamic Atomization
No full textElectrospray, or Electrohydrodynamic Atomization (EHDA), is a technique in which a high voltage is applied to a liquid to create aerosols. When a fluid is subjected to an adequately strong electric field induced by high voltage, its surface deforms into a cone from whose apex a jet is formed and disintegrates into microscale or nanoscale charged droplets. This multi-physics phenomenon can be applied in various areas, such as medicine delivery, 3-D printing, space thruster design, etc., owing to its low cost, high production rate and ease of control compared with other techniques. In electrospray, spraying regime can be controlled by varying parameters such as applied voltage, liquid flow rate, spraying distance, etc., and the most desirable spraying mode is the single cone-jet due to its stability, controllability, and relatively high yield rate. In this work, the authors introduce a simulation code to investigate the characteristics of electrospray operating in the cone-jet mode utilizing OpenFOAM. In our simulations, Gauss’s Law and Charge Conservation Equation are solved simultaneously with Navier-Stokes equations and VOF interface tracking method to numerically produce transient multiphase electrohydrodynamic mechanism. Computational results are validated by experimental data with close agreement.No Full Tex
Computational and experimental study on ion wind scheme based aerosol sampling for biomedical applications
No full textIn this paper, an efficient electrostatic particle sampling system is developed based on the neutralized ion wind. Compare with the conventional schemes where unipolar ion is used to charge the airborne sample and the sampling stage is fixed as a part of high voltage circuit, the new approach allows sampling stage to be electrically floated and adds insignificant charge to the bioaerosol, thus reduces damages to the microorganisms while provides design flexibility and good collecting efficiency. The approach is suitable for the combination with a microfluidic interface to develop complex aerosol-to-hydrosol bio-samplers.Full Tex
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Enhancing Lateral Photovoltage Through Light-Trapping 3C-SiC/Si Microstructures
No full textIn this paper, we reported for the first time a micro-structured 3C-SiC/Si for enhancing the lateral photovoltaic effect (LPE). The 3C-SiC/Si device with a 5-μm-diameter micro-holes array structure demonstrated an approximately 50% increase in position sensitivity compared to the conventional design. A position sensitivity up to 453.2 mV/mm was achieved in the 5-μm micro-holes array device under the illumination of 637 nm (2000 μW) light. This sensitivity is the highest reported for 3C-SiC/Si heterostructure at a working distance of 1000 μm and is among the highest sensitivity reported. Our findings further push the limit of the 3C-SiC/Si heterostructure for optoelectronic sensing applications and provide an excellent method for maximizing the LPE.No Full Tex
A study of ion wind generator using parallel arranged electrode configuration for centrifugal flow mixer
No full textIon wind is recently applied in various research areas such as the biomedical engineering, microfluidic mixing and particle manipulation. In this work, a bipolar ion wind generator configured by parallel arranged electrodes is used for centrifugal mixing applications. With the proposed configuration, negative and positive ion winds are simultaneously generated, mixed and then neutralized by each other while travelling toward liquid surface. The efficiency of the device was investigated both computationally and experimentally. The mixing of liquid occurred in different ways when the system is activated by either direct or alternating currents. Furthermore, the mixing is dependent on the dimension of electrode tip.No Full Tex
In Silico Analysis of Pulsatile Flow Veno-Arterial Extracorporeal Membrane Oxygenation on Human Aorta Model
No full textElectrocardiogram (ECG)—synchronized pulsatile veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is a recent development in extracorporeal therapy for patients with severe cardiogenic shock. Although preclinical studies have shown benefits of pulsatile flow relative to continuous ECMO flow, none have explored the effects of the timing of ECMO pulses with respect to the cardiac cycle and its possible implications on ECMO complications. This study aimed to develop a computational fluid dynamics (CFD) model of V-A ECMO in a patient-specific human aorta and evaluate the effect of ECMO timing on cardiac unloading, surplus hemodynamic energy delivery, and mixing zone position. Using direct flow measurements from cardiogenic shock patients and an ECMO device, the model revealed that maximal left ventricular (LV) unloading occurred when the ECMO pulse was in early diastole (35–40% from LV peak systolic flow). Maximum surplus hemodynamic energy transmission to aortic branches occurred at 20% from LV peak systolic flow. This indicates a trade-off between heart afterload and hemodynamic energy delivery in selecting ECMO pulse timing. The mixing zone was primarily located in the aortic arch across timing configurations. Therefore, selecting ECMO pulse timing is crucial to maximizing the benefits of pulsatile flow in V-A ECMO treatment.Full Tex
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