Recent developments in catalyst synthesis using DBD plasma for reforming applications

The catalyst has a significant role in gas processing applications such as reforming technologies for H₂ and syngas production. The stable catalyst is requisite for any industrial catalysis application to make it commercially viable. Several methods are employed to synthesize the catalysts. However, there is still a challenge to achieve a controlled morphology and pure catalyst which majorly influences the catalytic activity in reforming applications. The conventional methods are expansive, and the removal of the impurities are major challenges. Nevertheless, it is not straightforward to achieve the desired structure and stability. Therefore, significant interest has been developed on the advanced techniques to take control of the physicochemical properties of the catalyst through non-thermal plasma (NTP) techniques. In this review, the systematic evolution of the catalyst synthesis using NTP technique is elucidated. The emerging DBD plasma to synthesized and effective surface treatment is reviewed. DBD plasma synthesized catalyst performance in reforming application for H₂ and syngas production is summarised. Furthermore, the status of DBD plasma for catalyst synthesis and proposed future avenues to design environmentally suitable and cost-effective synthesis techniques are discussed.     

Design of Nonlinear Servo Systems by the Fuzzy Method

This paper presents the design of nonlinear servo systems using the fuzzy method. The idea behind this control method is to divide the operating region of a nonlinear system into a collection of local linear servo control systems and apply the fuzzy method for calculation of the control input. The control input of each local linear servo system is calculated using the Davison–Smith method and the Hikita pole assignment method. We can prove that all states of the fuzzy servo system are bounded and that the output errors converge to zero by the Lyapunov method. Simulations on a nonlinear mass‐spring‐damper system illustrate the effectiveness of the proposed method.     

Vibro-acoustic analysis of free piston engine structure using finite element and boundary element methods

This paper presents the results of vibro-acoustic modeling and simulation using the finite element and the boundary element methods for the free piston engine structure. A model of the engine was constructed through the use of finite element software to perform a normal mode analysis of the engine structure. The objective was to determine the mode shapes and the natural frequency that contribute to engine structure vibration. Theoretical development of the engine balance motion and frequency response was also conducted. From the simulation and finite element analysis, the force response pattern of the engine vibration was determined and then compared with its natural frequency. The vibration data were used as the input data for noise analysis using the boundary element method. The integration of the finite element and the boundary element determined the noise-frequency data of the engine structure toward the occurrence of engine noise. The information can be used by designers to analyze engine specifications and structure, especially at the preliminary design stage.     

Enhancing the Tribological Behavior of Lubricating Oil by Adding TiO2, Graphene,and TiO2/Graphene Nanoparticles

This article investigates the tribological behavior of nanoparticles (NPs) of titanium dioxide anatase TiO₂ (A), graphene, and TiO₂ (A) + graphene added to the pure base oil group ΙΙ (PBO-GΙΙ). The morphology of these two nanostructures of TiO₂ (A) and graphene was characterized by transmission electron microscopy (TEM). Oleic acid (OA) was blended as a surfactant into the formulation to help stabilize the NPs in the lubricant oil. A four-ball test rig was used to determine the tribological performance of six different samples, and an image acquisition system was used to examine and measure the wear scar diameter of the stationary balls. Field emission–scanning electron microscopy (FE-SEM) was used to examine the wear morphology. Energy-dispersive X-ray spectroscopy (EDX), element mapping, and Raman spectroscopy were employed to confirm the presence of (TiO₂ (A) + graphene) and the formation of a tribolayer/film on the mating surfaces. Moreover, a 3D optical surface texture analyzer was utilized to investigate the scar topography and tribological performance. The experiments proved that adding (0.4?wt% TiO₂ (A) + 0.2?wt% graphene) to the PBO-GΙΙ optimized its tribological behavior. These excellent results can be attributed to the dual additive effect and the formation of a tribofilm of NPs during sliding motion. Furthermore, the average reductions in the coefficient of friction (COF), wear scar diameter (WSD), and specific wear rate (SWR) were 38.83, 36.78, and 15.78%, respectively, for (0.4?wt% TiO₂ (A) + 0.2?wt% graphene) nanolubricant compared to plain PBO-GΙΙ lubricant.     

Clean hydrogen generation and storage strategies via CO2 utilization into chemicals and fuels: A review

Hydrogen becomes one of the most clean energy sources. The major issues on hydrogen are lack of practical clean and high‐temperature processes and possible practical storage of clean hydrogen. An energy intensive of clean hydrogen storage via chemical and liquid fuel production route is the current demand. This article reviewed the most recent research for hydrogen (H₂) production by using several methods, such as thermochemical process, thermal decomposition, biological approaches, electrolysis, and photocatalytic method. H₂ storage types, including physical and chemical approaches, were also reviewed. The produced H₂ was stored as valuable chemicals and fuels via CO₂ hydrogenation reaction. Reactor designs are the illustrated number of design ranging from the fixed bed to the continuous stirred tank reactor. Catalyst type, catalytic system, and the related mechanism of CO₂ hydrogenation reaction to form alcohol, alkanes, and carboxylic acid were also discussed in detail.     

Design and eco-technoeconomic analyses of SOFC/GT hybrid systems accounting for long-term degradation effects

This study compares two SOFC/GT (solid oxide fuel cell with gas turbine) hybrid systems to that of two standalone SOFC systems via eco-technoeconomic analyses that account for long-term degradation effects. Four cases were examined: 1) standalone SOFC plant without a steam bottoming cycle; 2) standalone SOFC plant with a steam bottoming cycle; 3) SOFC/GT hybrid plant without a steam bottoming cycle; and 4) SOFC/GT with a steam bottoming cycle. This study employed a real-time 1D SOFC model with an empirical degradation calculation integrated with steady-state balance-of-plant models. Simulations used Matlab Simulink R2017a, Aspen Plus V10, and Python 3.7.4 with a pseudo steady-state approach. The results showed that, with some trade-offs, the SOFC/GT hybrid plant with the steam bottoming cycle is the best option, with an overall efficiency of 44.6% _LHV, an LCOE (levelized cost of electricity) of $US 77/MWh, and a CCA (cost of CO₂ avoided) of -$US 49.3/tonneCO₂e. The sensitivity analysis also indicated that SOFC/GT hybrid plants were less sensitive to SOFC price compared to standalone SOFC plants. The sensitivity analysis indicated that using a larger gas turbine and replacing the SOFC stack less frequently was the better design choice for the SOFC/GT hybrid plant.     

Do personality problems improve during psychodynamic supportive–expressive psychotherapy? Secondary outcome results from a randomized controlled trial for psychiatric outpatients with personality disorders.

Studies involving patients with personality disorders (PDs) have not focused on improvement of core aspects of the PD. The authors examined changes in quality of object relations, interpersonal problems, psychological mindedness, and personality traits in a sample of 156 patients with Diagnostic and Statistical Manual of Mental Disorders (4th ed.) PD diagnoses being randomized to either manualized or nonmanualized dynamic psychotherapy. Effect sizes adjusted for symptomatic change and reliable change indices were calculated. The authors found that both treatments were equally effective at reducing personality pathology. Only in neuroticism did the nonmanualized group do better during the follow-up period. The largest improvement was found in quality of object relations. For the remaining variables, only small and clinically insignificant magnitudes of change were found. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Zero-current Switching Series Resonant High-voltage DC-DC Converter with Series-connected Primary Windings of Center-tapped Transformer

Abstract—This article proposes a novel zero-current switching series resonant inverter-fed voltage multiplier based high-voltage DC-DC converter. The series resonant inverter in the proposed topology has two power switches (insulated-gate bipolar transistors), two resonant capacitors, and only one high-voltage transformer with center-tapped primary windings. The power switches are connected in the form of a half-bridge network. The leakage inductances of the transformer's primary windings together with resonant capacitors form two series resonant circuits. The series resonant circuits are fed alternately by operating power switches with an interleaved half-switching cycle. The secondary winding of the high-voltage transformer is connected to a voltage multiplier circuit to rectify and boost the voltage. The converter operates in discontinuous conduction mode, and its output voltage is regulated by pulse-frequency modulation. Therefore, all the power switches turn ON and OFF at the zero-current switching condition. The main features of the proposed converter are lower power loss, less cost, and smaller size compared to previously proposed series resonant high-voltage DC-DC converters. The experimental results of a 130-W prototype of the proposed converter are presented both for dynamic and steady-state operation. The results confirm the excellent operation and performance of the converter.