Research progress in friction stir processing of magnesium alloys and their metal matrix surface composites: Evolution in the 21^(st )century

Rising concerns about climate change drive the demand for lightweight components.Magnesium(Mg)alloys are highly valued for their low weight,making them increasingly important in various industries.Researchers focusing on enhancing the characteristics of Mg alloys and developing their Metal Matrix Composites(MMCs)have gained significant attention worldwide over the past decade,driven by the global shift towards lightweight materials.Friction Stir Processing(FSP)has emerged as a promising technique to enhance the properties of Mg alloys and produce Mg-MMCs.Initially,FSP adapted to refine grain size from the micro to the nano level and accelerated the development of MMCs due to its solid-state nature and the synergistic effects of microstructure refinement and reinforcement,improving strength,hardness,ductility,wear resistance,corrosion resistance,and fatigue strength.However,producing defect-free and sound FSPed Mg and Mg-MMCs requires addressing several variables and their interdependencies,which opens up a broad range of practical applications.Despite existing reviews on individual FSP of Mg,its alloys,and MMCs,an attempt has been made to analyze the latest research on these three aspects collectively to enhance the understanding,application,and effectiveness of FSP for Mg and its derivatives.This review article discusses the literature,classifies the importance of Mg alloys,provides a historical background,and explores developments and potential applications of FSPed Mg alloys.It focuses on novel fabrication methods,reinforcement strategies,machine and tool design parameters,material characterization,and integration with other methods for enhanced properties.The influence of process parameters and the emergence of defects are examined,along with specific applications in mono and hybrid composites and their microstructure evolution.The study identifies promising reinforcement materials and highlights research gaps in FSP for Mg alloys and MMCs production.It concludes with significant recommendations for further exploration,reflecting ongoing advancements in this field.

Sustainable Furfural Biomass Feedstocks Electrooxidation toward Value-Added Furoic Acid with Energy-Saving H_(2) Fuel Production Using Pt-Decorated Co_(3)O_(4) Nanospheres

Here,furfural oxidation was performed to replace the kinetically sluggish O_(2)evolution reaction(OER).Pt-Co_(3)O_(4)nanospheres were developed via pulsed laser ablation in liquid(PLAL)in a single step for the paired electrocatalysis of an H_(2)evolution reaction(HER)and furfural oxidation reaction(FOR).The FOR afforded a high furfural conversion(44.2%)with a major product of 2-furoic acid after a 2-h electrolysis at 1.55 V versus reversible hydrogen electrode in a 1.0-M KOH/50-mM furfural electrolyte.The Pt-Co_(3)O_(4)electrode exhibited a small overpotential of 290 mV at 10 mA cm^(-2).As an anode and cathode in an electrolyzer system,the Pt-Co_(3)O_(4)electrocatalyst required only a small applied cell voltage of~1.83 V to deliver 10 mA cm^(-2),compared with that of the pure water electrolyzer(OER||HER,~1.99 V).This study simultaneously realized the integrated production of energy-saving H_(2)fuel at the cathode and 2-furoic acid at the anode.

Surface Morphology and Thermo-Electrical Energy Analysis of Polyaniline (PANI) Incorporated Cotton Fabric

With the exponential development in wearable electronics,a significant paradigm shift is observed from rigid electronics to flexible wearable devices.Polyaniline(PANI)is considered as a dominant material in this sector,as it is endowed with the optical properties of both metal and semiconductors.However,its widespread application got delineated because of its irregular rigid form,level of conductivity,and precise choice of solvents.Incorporating PANI in textile materials can generate promising functionality for wearable applications.This research work employed a straightforward in-situ chemical oxidative polymerization to synthesize PANI on Cotton fabric surfaces with varying dopant(HCl)concentrations.Pre-treatment using NaOH is implemented to improve the conductivity of the fabric surface by increasing the monomer absorption.This research explores the morphological and structural analysis employing SEM,FTIR and EDX.The surface resistivity was measured using a digital multimeter,and thermal stability is measured using TGA.Upon successful polymerization,a homogenous coating layer is observed.It is revealed that the simple pre-treatment technique significantly reduces the surface resistivity of Cotton fabric to 1.27 kΩ/cm with increasing acid concentration and thermal stability.The electro-thermal energy can also reach up to 38.2°C within 50 s with a deployed voltage of 15 V.The modified fabric is anticipated to be used in thermal regulation,supercapacitor,sensor,UV shielding,antimicrobial and other prospective functional applications.

Biochemical and physical investigations on detoxification of ginkgo kernel juice using probiotic fermentation with macroporous resin addition

The toxicity of ginkgo kernel is a global concern,restricting its consumption as a medicinal food.This study focuses on eliminating the toxic components,specifically ginkgolic acid,from ginkgo kernel juice.The approach used was probiotic fermentation with autochthonous lactic acid bacteria combined with macroporous resin.Compared to using lactic acid fermentation alone,adding macroporous resin during probiotic fermentation significantly enhanced the removal of toxic ginkgolic acid and 4'-O-methylpyridoxine from ginkgo kernel juice.After 48 h of fermentation with macroporous resin,the contents of ginkgolic acid and 4'-O-methylpyridoxine decreased by more than 69%and 61%,respectively.Interestingly,the adsorption of microbial growth inhibitors,such as ginkgolic acid,4'-O-methylpyridoxine,and phenolics,by the resin did not hinder the growth of lactic acid bacteria or their metabolic activities involving organic acids and monosaccharides.The study further confirmed that microbial adsorption was the primary reason for removing ginkgolic acid during probiotic fermentation.Also,the adsorption mechanism of ginkgolic acid during probiotic fermentation with macroporous resin was explored.From a mass transfer perspective,incorporating macroporous resin during the probiotic fermentation of ginkgo kernel juice reduced the mass transfer resistance for surface diffusion.Consequently,this lowered the contribution of surface diffusion to the overall diffusion process and facilitated the efficient removal of toxic ginkgolic acid.This work can help to understand the physical mechanism regarding detoxification of ginkgo kernel juice by probiotic fermentation,and offer potential strategies to enhance the safety of ginkgo kernel products.

Phylogenetic and morphometric relationships between two species of genus Auxis from the South China Sea and Java Sea

This study was aimed at examining the phylogenetic and morphometric relationship of frigate tuna（Auxis thazard） and bullet tuna（Auxis rochei） using mt DNA D-loop（control） region sequences and truss measurements,respectively. Maximum-likelihood（ML） tree and median-joining network showed that haplotypes from Auxis populations grouped separately. Discriminant function analyses and non-metric multidimensional scaling of morphometric data showed that bullet and frigate tuna were differed mainly with respect to truss measurements on the anterior region, suggesting adaptation to different diets available in different environments. Historic demographic analyses of sequence data showed that both bullet and frigate tuna had not undergone a significant sudden population expansion recently. Non-significant value of Tajimas＇ s D and Fu＇s F_S were indicated an effective large and stable population size for longer period of both species in South China Sea and Java Sea species. This study gives first report on the complementary relationship between morphometric and genetic analysis in stock discrimination of genus Auxis.

Technical and Vocational Education Training in Brunei Darussalam——Pathway to Higher Educations

In the 21stcentury educational landscape,higher educational institutions(HEI)play a crucial role in the shaping of social and economic strategies of a developing country.HEI’s main role is to develop and train the workforce for the middle to higher level employment.Technical and vocational education(TVE)on the other hand,plays the role in filling the major work force at the lower or blue collar level and at the same time,providing pathways and opportunities for them to pursue further educational needs.In Brunei Darussalam,HEI works closely with TVE to ensure there is a continuation pathway for TVE to HEI although there are fundamental differences in the philosophy,pedagogy and assessment measures.In Universiti Teknologi Brunei(UTB),the design of the curriculum has always been outcome based;heavily related to skills and practices of the job market,similar to TVE’s teaching and learning philosophy.In this study,we are looking at the brief development of TVE and HE across the world and Brunei,the qualification framework of Brunei and curriculum design of UTB.The study will highlight how UTB provides a smooth transition for TVE feeders to the university to support the value of practical learning in workplace settings,combined with conceptual learning in an academic setting.The primary role of UTB is to assist graduates in the transition to professional practice.

Power-to-gas technology in energy systems:current status and prospects of potential operation strategies

Regarded as a long-term, large capacity energy storage solution, commercialized power-to-gas(PtG) technology has attracted much research attention in recent years.PtG plants and natural gas-fired power plants can form a close loop between an electric power system and a natural gas network. An interconnected multi-energy system is believed to be a solution to the future efficient and environmental friendly energy systems. However, some crucial issues require in-depth analysis before PtG plants can be economically implemented. This paper discusses current development status and potential application of PtG plants in the future interconnected multi-energy systems, and further analyzes the costs and benefits of PtG plants in different application scenarios. In general, the PtG plants are not economical efficient based on current technologies and costs. But the situation is likely to change with the development of PtG technologies and interconnected operation of gas-electricity energy system.

Congestion management with demand response considering uncertainties of distributed generation outputs and market prices

In recent years,much attention has been devoted to the development and applications of smart grid technologies,with special emphasis on flexible resources such as distributed generations(DGs),energy storages,active loads,and electric vehicles(EVs).Demand response(DR) is expected to be an effective means for accommodating the integration of renewable energy generations and mitigating their power output fluctuations.Despite their potential contributions to power system secure and economic operation,uncoordinated operations of these flexible resources may result in unexpected congestions in the distribution system concerned.In addition,the behaviors and impacts of flexible resources are normally highly uncertain and complex in deregulated electricity market environments.In this context,this paper aims to propose a DR based congestion management strategy for smart distribution systems.The general framework and procedures for distribution congestion management is first presented.A bi-level optimization model for the day-ahead congestion management based on the proposed framework is established.Subsequently,the robust optimization approach is introduced to alleviate negative impacts introduced by the uncertainties of DG power outputs and market prices.The economic efficiency and robustness of the proposed congestion management strategy is demonstrated by an actual 0.4 kV distribution system in Denmark.

Controlled islanding schemes for interconnected power systems based on coherent generator group identification and wide-area measurements

A reasonable islanding strategy of a power system is the final resort for preventing a cascading failure and/or a large-area blackout from occurrence. In recent years, the applications of wide area measurement systems(WAMS) in emergency control of power systems are increasing. Therefore, a new WAMS-based controlled islanding scheme for interconnected power systems is proposed. First, four similarity indexes associated with the trajectories of generators are defined, and the weights of these four indexes are determined by using the well-developed entropy theory. Then, a coherency identification algorithm based on hierarchical clustering is presented to determine the coherent groups of generators.Secondly, an optimization model for determining controlled islanding schemes based on the coherent groups of generators is developed to seek the optimal cutset. Finally, a 16-generator68-bus power system and a reduced WECC 29-unit 179-bus power system are employed to demonstrate the proposed WAMS-based controlled islanding schemes, and comparisons with existing slow coherency based controlled islanding strategies are also carried out.

Aggregated impact of allowance allocation and power dispatching on emission reduction

Climate change has become one of the most important issues for the sustainable development of social well-being.China has made great efforts in reducing CO2 emissions and promoting clean energy.Pilot Emission Trading Systems(ETSs)have been launched in two provinces and five cities in China,and a national level ETS will be implemented in the third quarter of 2017,with preparations for China’s national ETS now well under way.In the meantime,a new round of China’s electric power system reform has entered the implementation stage.Policy variables from both electricity and emission markets willimpose potential risks on the operation of generation companies(Gen Cos).Under this situation,by selecting key variables in each domain,this paper analyzes the combined effects of different allowance allocation methods and power dispatching models on power system emission.Key parameters are set based on a provincial power system in China,and the case studies are conducted based on dynamic simulation platform for macro-energy systems(DSMES)software developed by the authors.The selected power dispatching models include planned dispatch,energy saving power generation dispatch and economic dispatch.The selected initial allowance allocation methods in the emission market include the grandfathering method based on historical emissions and the benchmarking method based on actual output.Based on the simulation results and discussions,several policy implications are highlighted to help to design an effective emission market in China.

Soil resistivity and ground resistance for dry and wet soil

In this paper, soil resistivity and ground resistance at two different sites near an electrical substation are measured using a grounding system grid with and without rods. With the Wenner four-pole equal-method, the soil resistivity is measured at both selected sites, one of which contains wet soil while the other contains dry soil. Cymgrd simulation software is then used to determine the acceptability of these measured resistivity values by finding out the root mean square error between the measured and calculated values for both wet and dry soil sites. These values for wet and dry soil sties were found to be only 0 %and 4.92 %, respectively, and deemed acceptable. The measured soil resistivity values were then used to evaluate the ground resistance values of a grounding grid ‘with rod’for the wet soil site and ‘without rods’ for the dry soil site,and then compared with the simulated ground resistance values. These comparisons were also found to be in good agreement. In addition, ground potential rise, maximum permissible step and touch potentials have also been estimated using the simulation software.

Modeling of a long sand-pack for heavy crude oil through depletion tests utilizing methane gas

With the enormous increase in the demand for crude oil,and decrease in the resources of conventional oil reservoirs,there is a great need to understand heavy or foamy oil-gas drive mechanism to maximize the oil and gas production.To analyze the real movement of non-viscous heavy oil flow,the characteristic features of the oil-gas mixture has to be estimated to forecast the future potential supply from a heavy oil reservoir.An important question in heavy oil flow under solution gas drive is whether the behaviour of depletion tests can be simulated to model the heavy oil flow behaviour.The main objective of this research is to develop a reliable numerical model for modelling heavy oil flow calibrated with controlled solution gas drive experiments,and that makes a novelty in this manuscript.In this paper,CMG-STARS model which is capable of simulating solution gas drive tests that matched the research experiments.This heavy oil recovery model can determine the relative permeability curves for oil and gas in the dualphase system using Corey’s relations.At a depletion rate of 0.0418 psi/min,the maximum cumulative oil and gas production was observed to be 13,000 cm^(3)and 8500 cm^(3),respectively.The results from the bottom hole pressure and the block pressure simulation runs indicate that the fluid properties such as surface tension plays a significant role in the gas bubble formation.These results are promising,and helps to understand the complex behaviour of heavy oil reservoirs and thus can improve heavy oil recovery.

Perturbation analysis for pulsatile flow of Carreau fluid through tapered stenotic arteries

The pulsatile flow of blood in a tapered narrow artery with overlapping time-dependent stenosis is mathematically analyzed, modeling blood as Caxreau fluid. Perturbation method is employed for solving the resulting nonlinear system of equations along with the appropriate boundary conditions. The analytic solutions to the pressure gradient, velocity distribution, flow rate, wall shear stress and longitudinal impedance to flow axe obtained in the asymptotic form. The variation of the aforesaid flow quantities with respect to various physical parameters such as maximum depth of the stenosis, angle of tapering of the artery, power law index, Reynolds number, pulsatile amplitude of the flow and Weissenberg number is investigated. It is found that the wall shear stress and longitudinal impedance to flow increase with the increase of the angle of tapering of the artery, the maximum depth of the stenosis and pulsatile Reynolds number and these decrease with the increase of the amplitude of the flow, power law index and Weis- senberg number. The mean velocity of blood decreases significantly with the increase of the artery radius, maximum depth of the stenosis, angle of tapering of the artery.