Photovoltaic (PV) technology is one of the key answers for a better sustainable future. An important layer in the structure of common PV cells is the transparent conductive oxide (TCO). A widely applied TCO is tin oxide. The advantage of using tin oxide comes from its high stability, and it is inexpensive in terms of raw materials and processing techniques. We discuss our study of depositing thinfilm tin oxide layer by utilizing magnetron RFsputtering technique while varying the Ar inert gas flow rate and oxygen content. Preliminary results showed that sheet resistance values obtained for the tin oxide films spanned across four orders of magnitude in their asdeposited amorphous conditions, and transmittance values extending from 47 to 90% within the visible light spectrum.
Unique properties such as high porosity, large surface area, inducible wettability, high mechanical strength, and high chemical activity are excellent reasons to make MWCNTs an interesting area of research as Vanadium Redox Flow Batteries (VRFBs) electrodes materials. In this experimental work, freestanding sheets of MWCNTs, known as buckypapers, were fabricated. A ball milling process was performed as a pretreatment to fabricate electrodes for VRFBs. The effects of various ball milling speeds on the electrodes performance was studied? Surface area, amount of debundling, and amount of defects increased as ball milling speeds increased, as proven by SEM Microscopy and Raman Spectroscopy. Electrochemical performance improved as ball milling speeds increased as evident by Voltammetry.
Crack propagation emanating from holes in specimens made of PMMA is studied. Fracture tests on several specimens are conducted to examine their fracture performance under ModeI and Mixed Mode (I and II) loading. Each specimen has central hole and initial symmetrical cracks of certain length and at specific angle. During testing, the load versus overhead displacement is determined. Results show that, after initiation, cracks will propagate almost along the surface perpendicular to the applied load. The maximum load needed for full specimen separation highly depends on the initial crack length and the angle at which the initial crack is created. The Jintegral value increases with the angle for the same crack length and decreases with crack length for the same angle.
Over the last decade, Nonlinear Energy Sinks (NESs) have experienced a significant development and gained rapidgrowing interest. One of the recent new types of NESs is the rotating NESs which has further been enhanced recently to incorporate an elastic arm and therefore another degree of freedom is added. This article presents the numerical simulations of attaching two rotating elastic NESs to the top and second top floors of a real life ninestory structure.
Current study presents an experimental work on the thermal augmentation and pressure penalty in a constant heatfluxed circular duct with vortex generators insert. The experiment was conducted in turbulent flow regime with a Reynolds number ranging from 6000 to 27000. The results suggested that by increasing the length of winglet, both heat transfer coefficient and friction factor will intensify. With lower pitch ratio, higher Nusselt number and friction factor are achieved. The maximum heat transfer efficiency is obtained for the length of 20 mm, pitch ratio of 1.6 and Reynolds number of 27000. However, the highest thermal enhancement factor of 1.59 is obtained for the length of 10 mm, pitch ratio of 4.8 and Reynolds number of 6000. The flow structure was also precisely portrayed.
This paper presents energy models of the variable refrigerant flow (VRF) technology. VRF is an advanced type of air conditioning systems proposed to be implemented in Masdar EcoVillas in Abu Dhabi. VRF units manufactured by Daikin and LG companies were both modeled and compared using engineering equation solver (EES) software. The models done on EES were repeated for validation on IPSEpro software, and the results were similar within 4% error. Finally, different refrigerants were modeled and the results showed that refrigerant R410a would be the second most efficient refrigerant for such systems. The model results have been validated with the Daikin system installed in Dubai.
Unipolar RRAM devices are of high interest due to their high resistance ratio and simple selector circuit. In this paper, we report on a measurements from nanothick memristor featuring a novel Pd/Hf/HfO2/Pd stack. The fabricated device exhibits a unipolar switching behavior, due to the asymmetric device structure and the existence of the Pd metal as a bottom electrode. The electrical characteristics of the memristor are studied for different device sizes that vary from 50 ?m to 1000 ?m. Although increasing the device size reduces the required switching voltage of the memristor, this reduction saturates at device size of 200 ?m for the same stack thicknesses. The findings presented in this work highlight the impact of device geometry on its electrical performance and power, which provide guidance to the design tradeoffs (size, power, resistance ratio) and fabrication process of memristor devices.
in this paper, nitration of germanium surface using a mixture of N2O, NH3 and N2 is performed using RFPECVD reactor. The electrical characteristics of Al/HfO2/GeON/pGe capacitors are investigated. Results show that the hysteresis of metaloxidesemiconductor (MOS) capacitors with nitrationbased passivation step is reduced to ~150 mV, compared with ~400mV of the untreated sample. The suppression of hysteresis is attributed to the reduction of electron traps and enhancement of dielectric/Ge interface quality. The improved interface quality of plasmabased nitration of Ge surface is a promising technique for high performance Ge MOSFET fabrication
In this paper, the design and simulation of a shortchannel (0.5 ?m) 4HSiC power DMOSFET is presented. The design aspects are associated with tradeoffs that are discussed in the paper. The structure is optimized for high blocking voltage of up to 1200 V at 27 ?C, and it exhibits offstate leakage currents of <1020 A in the forward state. Even though high blocking voltages are possible in DMOSFETs, they still suffer from low current densities due to low channel mobility at the surface. To address this issue, the use of alternate dielectrics is suggested.
In this paper, a digital programmable balanced OTA is proposed. The OTA employs three linearization techniques which are the source degeneration, double differential pair technique and the adaptive biasing. The digital programmability is achieved by using two current division networks (CDNs). The thirdorder harmonic distortion (HD3) remains below 60 dB for 0.6 V input voltage at 1.2 V supply voltage. The proposed OTA performance is validated by SPICE simulation using TSMC 90 nm technology.
