Impact behaviour of aluminum particles upon aluminum, magnesium, and titanium substrates using high pressure and low-pressure cold spray

This study is focused on the impact and residual stress behaviour of aluminum component repair using aluminum powder via two different types of cold spray processes; high pressure cold spray (HPCS) and low-pressure cold spray (LPCS). It has been carried out via smoothed particle hydrodynamics simulations, comparing aluminum substrate with other lightweight materials such as titanium and magnesium. The obtained results have shown that the impact behaviour is influenced by velocity, porosity, deformation behaviour, flattening ratio, total energy and maximum temperature. The aluminum particles impacting on aluminum substrates using LPCS is slightly deformed, with the smallest flattening ratio leading to less pore formation between the particles. This has subsequently resulted in good coating quality. Furthermore, HPCS has contributed greatly to the deposition of particles on the heavier and harder substrate, such as titanium substrate. Thus, the overall result indicates that LPCS is better for repairing aluminum component compared to HPCS

Evolution of digitally controlled oscillator

Suvremeni razvoj uporabe digitalnih ili potpuno digitalnih ciklusa s faznim podešavanjem (PLLs) u različitim uređajima za komunikaciju vodi ka primjeni digitalno kontroliranog oscilatora (DCO). U ovom se preglednom članku daje razvoj DCO-a u modernim elektroničkim uređajima kao i njihovo funkcioniranje u lokalnim oscilatorima. Iako se implementacija DCO preferira u odnosu na analogne, i dalje se radi na poboljšanjima u potrošnji energije, brzini, veličini čipa, raspona frekvencije, ulaznog napona, prenosivosti i rezolucije. U radu se uglavnom opisuje razvoj od oscilatora kontroliranih voltažom (voltage controlled oscillators- VCO) do digitalno kontroliranih oscilatora za "deep-submicrometer CMOS" postupak. Fokus je na analizi i praćenju unapređenja DCO-a na razini funkcionalnosti.Current trend of using digital or all-digital phase-locked loops (PLLs) in various communication devices introduces the usage of digitally controlled oscillator (DCO). This review paper discusses the evolution of DCOs in modern electronic devices as well as their performances in local oscillators. Even though the DCO implementation is preferable to its analog counterpart, improvements are still going on to get high performances in terms of power consumption, speed, chip area, frequency range, supply voltage, portability and resolution. This paper mainly describes the evolution of DCO, how it turns from a conventional VCO to DCO for deep-submicrometer CMOS process. The focus is to analyse and track the advances in DCO base on its performance level

Evolution of digitally controlled oscillator

Suvremeni razvoj uporabe digitalnih ili potpuno digitalnih ciklusa s faznim podešavanjem (PLLs) u različitim uređajima za komunikaciju vodi ka primjeni digitalno kontroliranog oscilatora (DCO). U ovom se preglednom članku daje razvoj DCO-a u modernim elektroničkim uređajima kao i njihovo funkcioniranje u lokalnim oscilatorima. Iako se implementacija DCO preferira u odnosu na analogne, i dalje se radi na poboljšanjima u potrošnji energije, brzini, veličini čipa, raspona frekvencije, ulaznog napona, prenosivosti i rezolucije. U radu se uglavnom opisuje razvoj od oscilatora kontroliranih voltažom (voltage controlled oscillators- VCO) do digitalno kontroliranih oscilatora za "deep-submicrometer CMOS" postupak. Fokus je na analizi i praćenju unapređenja DCO-a na razini funkcionalnosti.Current trend of using digital or all-digital phase-locked loops (PLLs) in various communication devices introduces the usage of digitally controlled oscillator (DCO). This review paper discusses the evolution of DCOs in modern electronic devices as well as their performances in local oscillators. Even though the DCO implementation is preferable to its analog counterpart, improvements are still going on to get high performances in terms of power consumption, speed, chip area, frequency range, supply voltage, portability and resolution. This paper mainly describes the evolution of DCO, how it turns from a conventional VCO to DCO for deep-submicrometer CMOS process. The focus is to analyse and track the advances in DCO base on its performance level

Thermal Stability of Rare Earth-PYSZ Thermal Barrier Coating with High-Resolution Transmission Electron Microscopy

Durability of a thermal barrier coating (TBC) depends strongly on the type of mixed oxide in the thermally grown oxide (TGO) of a TBC. This study aims on discovering the effect of thermal stability in the TGO area containing mixed oxides. Two different bondcoats were studied using high-resolution transmission electron microscopy: high-velocity oxygen fuel (HVOF) and air-plasma spray (APS), under isothermal and thermal cyclic tests at 1400 °C. The HVOF bondcoats were intact until 1079 cycles. In comparison, APS failed at the early stage of thermal cycling at 10 cycles. The phase transformation of topcoat from tetragonal to the undesired monoclinic was observed, leading to TBC failure. The results showed that the presence of transient aluminas found in HVOF bondcoat helps in the slow growth of α-Al2O3. In contrast, the APS bondcoat does not contain transient aluminas and transforms quickly to α-Al2O3 along with spinel and other oxides. This fast growth of mixed oxides causes stress at the interface (topcoat and TGO) and severely affects the TBC durability leading to early failure. Therefore, the mixed oxide with transient aluminas slows down the quick transformation into alpha-aluminas, which provides high thermal stability for a high TBC durability

Impedance analysis of charge transfer upon nickel doping in Tio2-based flexible dye-sensitized solar cell

Flexible dye-sensitized solar cells (FDSSCs) have promoted interest in plastic industries as they are lightweight, flexible, and mechanically robust to accelerate production and reduce cost. However, the plastic substrates have temperature limitations in producing the TiO2 photoanode and degrade the performance of FDSSC. The main reason for this degradation is the low charge transfer in the photoanode layer. Although there is plenty of research on low-temperature fabrication methods, they indirectly increase the operational cost. Therefore, a new approach is necessary for charge transfer improvement without affecting the temperature in a low-cost platform. In this study, we present a photoanode that improves the charge transfer by doping nickel (Ni) in the TiO2 layer. A low amount of Ni doping (15%) exhibited Rct >> Rt, indicating a high charge transport and low electron recombination rate (120.84 s−1). On the other hand, higher amount Ni doping (>> 45%) has Rct << Rt which deteriorates the performance of the cell by causing severe agglomeration issues, indicating a high electron recombination rate (369.75 s−1). Moreover, the high charge transfer in (TiO2)85-Ni15-based FDSSC facilitates the electron lifetime of the cell up to 8.28 ms. Therefore, an optimum doping of Ni in TiO2-based FDSSC is studied in this work

Current advancement of flexible dye sensitized solar cell: A review

In the last two decades, research on dye-sensitized solar cells (DSSCs) has shown tremendous improvement with promising findings. It has become one of the alternative options in replacing conventional silicon-based photovoltaics. Recently, a study towards the flexible form of solar cells has gained the attention of researchers. The features possess in DSSC such as high flexibility, light weight and environmentally friendly have made DSSC suitable for such purposes compared to rigid glass substrates. However, the biggest challenge faced by plastic-type substrates is temperature, where plastic substrates only withstand up to 150 ◦C before melting. In the DSSC fabrication process, temperatures as high as 400–500 ◦C are critically required for the purpose of material crystallization. With insufficient temperature during this process, poor interconnection between nanoparticles and increased electrode resistance will occur, thereby lowering the performance of plastic based DSSC. Here, we discuss the approaches that researchers have performed in solving the problem. Such approaches include the use of doctor blades, electrophoretic deposition, hydrothermal, peel and stick technique, and pulse laser deposition methods. In addition, this paper also discusses the most recent method which is additional procedure using Titanium (IV) tetraisopropoxide or UV-O3 treatment in the preparation of flexible DSSC. Several types of photoanode materials such as titanium dioxide, zinc oxide and graphene are also discussed in this paper

Characterization of polyaniline–Ag–rGO nanocomposites for saprophytic and pathogenic Leptospira bacteria detection in water

This research aims to develop polyaniline (PANI)–Ag–rGO nanocomposite thin films to detect Saprophytic and Pathogenic Leptospira bacterias in water. The sol–gel method followed by a spin-coating technique was conducted in this work to synthesize nanocomposite thin films of PANI–Ag(1−x) –rGOx (x = 0.025, 0.050, 0.075, 0.100). The results revealed that PANI–Ag0.975–rGO0.025 thin film exhibited the most robust sensitivity, with the highest Ag concentration. The x-ray diffraction and field-emission scanning electron microscope analysis confirmed the structure of the nanocomposites with Ag nanospheres. The atomic force microscope study showed greater surface roughness for the nanocomposites with high Ag concentrations. Furthermore, PANI–Ag0.975–rGO0.025 nanocomposite possessed the highest electrical conductivity (2.81 Scm−1), which resulted in the excellent detection of Leptospira bacteria in water