Hasil untuk "Mechanical industries"

Yichun Li, Shuyue Li, Yaru Luo et al.

Abstract Taking climate actions is of increasing importance. The agricultural sector is exploring its carbon neutrality transition pathway. Current relevant studies paid limited attention to agricultural products such as table grapes. This study takes table grapes cultivation in Shanghai as a case study, employing the life cycle assessment (LCA) to account for the carbon emissions and environmental impacts of five different conditions, including open field, simple greenhouse, continuous greenhouse, continuous greenhouse with photovoltaic power, and improved continuous greenhouse with photovoltaic power. Utilizing both observation and simulation data, the SimaPro software is applied to analyze the LCA carbon and environmental footprints of table grapes cultivation. The results show that simple greenhouse grapes exhibit the lowest level of carbon emissions (452 kgCO2-eq/mu-year), and meanwhile the most economical. Moreover, improved greenhouse utilizing photovoltaic power (1.26 × 103kgCO2-eq/mu-year) exhibits higher carbon emissions, however with lower levels of environmental toxicity due to utilizing grapevines for organic fertilizers. Thus, simple greenhouse grapes would score best if considering carbon emissions only, while the improved greenhouse model holds greater potential as a form of modernized facility-based agriculture. Furthermore, this study suggests that for the broader facility agriculture, using low carbon structure materials would serve as the level to reduce carbon footprints.

Cecil Felix, Iosif Vazirgiantzikis, Mphoma Matseke et al.

Slot-die coating is a promising method for mass-producing membrane electrode assemblies for polymer electrolyte membrane fuel cells. Precise control of slot-die coating parameters and catalyst ink variables is essential for achieving defect-free catalyst layers. This study investigated catalyst ink rheology and coating windows of typical ink formulations and extremes. The influence of the dispersing solvent ratio, ionomer-to-carbon ratio, and Pt weight percentage on catalyst ink rheology and coating behaviour was examined. Inks with a 75%-water/25%-n-propanol dispersing solvent ratio exhibited shear-thinning and good coatability, while those with high water content (90%-water/10%-n-propanol) displayed Newtonian flow, leading to poor substrate wetting and coating. Increasing the ionomer-to-carbon ratio reduced the ink's viscosity, while increasing the Pt weight percentage increased the ink’s viscosity. While appearing defect-free, x-ray fluorescence and optical microscopy analyses revealed that the coated catalyst layers often displayed nonuniform Pt loadings and cracks, especially with increasing catalyst layer thickness. The nonuniform Pt loadings were attributed to variations in gas diffusion layer roughness, catalyst layer cracks, and limitations of the slot-die coater. Initial membrane electrode assembly performance tests underscored the importance of material selection, the ionomer overlayer, and hot-pressing to enhance performance.

Rui Feng

In this recapitulation, China’s policies towards simultaneously achieving carbon neutrality and enhancing national energy security are reviewed. Without considering the vital energy safety, formulating climate policies toward carbon neutrality would be like a snow-covered Alp in a desolate desert. Because China's energy consumption has been greater than its domestic energy production in the recent decade, importing foreign energy safely and timely has become a top priority. Thereby, China has deepened its connection with Russian, Iran, Pakistan, Myanmar, and Central Asian countries for energy cooperation, thus reshaping its roadmap towards CO2 emission reductions. Meanwhile, adjusting to strategical necessities and understanding future trends, China has proactively participated in the Arctic affairs to explore new resource frontier and sphere of influence. Also, China has boosted the developments of renewable energy, inclusive of wind, solar, hydro, nuclear, geothermal, and wave/tidal to rationalize energy structure and increase the capacity of energy production. From 2009–2021, the cumulative installed electricity-generating capacity of renewable energy in China had increased from 874 to 2374 million kW and the yearly power generation from 3697 to 8537 billion kW·h. With the enforcement of constructions of energy infrastructure under the framework of the Belt and Road Initiative (BRI), China has steadily promoted the internationalization of its currency, Renminbi (RMB).

Zihni Onur Uygun, Savas Tasoglu

Summary: This study presents the design and implementation of an antimicrobial peptide-based electrochemical impedance spectroscopy (EIS) based biosensor system. The biosensor consists of a gold coated carbon electrode with MXene and silver nanoparticles (AgNPs) for the label-free detection of the human immunodeficiency virus (HIV) envelope protein gp120. Scanning electron microscopy was used to confirm the presence and distribution of MXene and AgNPs on the biosensor surface. The employment of the antimicrobial peptide on the electrode surface minimized the denaturation of the biorecognition receptor to ensure reliable and stable performance. The biosensor exhibited a linear range of 10–4000 pg mL-1 for gp120 detection, demonstrating good repeatability in real samples. The limit of detection (LOD) and limit of quantification (LOQ) were also calculated as 0.05 pg mL−1 and 0.14 pg mL−1, respectively. This biosensing platform has promising applications in the detection of HIV in clinical and point-of-care settings.

Yansong Gao, A. Lifu, Chenxu Zhao et al.

This paper presents an evaluation method for the entropy-weighting of wind power clusters that comprehensively evaluates the allocation problems of wind power clusters by considering the correlation between indicators and the dynamic performance of weight changes. A dynamic layered sorting allocation method is also proposed. The proposed evaluation method considers the power-limiting degree of the last cycle, the adjustment margin, and volatility. It uses the theory of weight variation to update the entropy weight coefficients of each indicator in real time, and then performs a fuzzy evaluation based on the membership function to obtain intuitive comprehensive evaluation results. A case study of a large-scale wind power base in Northwest China was conducted. The proposed evaluation method is compared with fixed-weight entropy and principal component analysis methods. The results show that the three scoring trends are the same, and that the proposed evaluation method is closer to the average level of the latter two, demonstrating higher accuracy. The proposed allocation method can reduce the number of adjustments made to wind farms, which is significant for the allocation and evaluation of wind power clusters.

Cristina Parente, Francisca Teixeira, Jorge Cerdeira

Abstract Background There is a race to innovate, develop or create hydrogen production technologies to accelerate energy transition and create a hydrogen economy. Acceptance has been used in social science literature as a lens through which to anticipate possible challenges surrounding hydrogen technologies. However, very few studies problematize perceptions and focus on the production of hydrogen. Hence, this study aims to bridge these theoretical and empirical gaps using a mixed-method approach based on semi-structured interviews (n = 7) and a questionnaire survey (n = 73) to understand stakeholders’ perceptions of hydrogen production sources through a social construction of technology lens. Results The findings suggest a tendency to favor hydrogen produced from renewable sources and to reject hydrogen produced from non-renewable sources. All the examined groups conform to this pattern. Their perceptions are based on prior knowledge of hydrogen technologies, with participants seeking information from specialized sources or from activities promoted by their organizations. Participants anticipate that hydrogen will be generated primarily through renewable energy sources and utilized where direct electrification is unfeasible. In addition, they envisage that the hydrogen economy will enhance energy democracy through representative participation in decision-making. Nevertheless, it is acknowledged that the topic is limited to certain social groups and kept away from the public eye. Furthermore, unlike the benefits, the perception of risk appears to have no impact on perceptions’ construction. High confidence in science appears to minimize the recognition of potential risks and bolster the recognition of potential benefits. There is, however, a lot of uncertainty about the possible real impacts of the hydrogen economy. Conclusions There appears to be a collective perspective on hydrogen production sources, indicating the existence of social representations. Nevertheless, group attitudes and backing towards hydrogen vary. The participants identify hydrogen as a matter that remained unnoticed for over a decade, despite its prominent position in the policies and economic approaches of numerous countries. The topic has been relegated to third parties. This exclusion of civil society from decision-making may justify the NGO group's critical stance towards hydrogen. Moreover, it suggests that energy democracy, which is based on information dissemination and participation, is not being achieved.

Alexandr Sedykh, Maninadh Podapaka, Asel Sagingalieva et al.

Finding the distribution of the velocities and pressures of a fluid by solving the Navier–Stokes equations is a principal task in the chemical, energy, and pharmaceutical industries, as well as in mechanical engineering and in design of pipeline systems. With existing solvers, such as OpenFOAM and Ansys, simulations of fluid dynamics in intricate geometries are computationally expensive and require re-simulation whenever the geometric parameters or the initial and boundary conditions are altered. Physics-informed neural networks (PINNs) are a promising tool for simulating fluid flows in complex geometries, as they can adapt to changes in the geometry and mesh definitions, allowing for generalization across fluid parameters and transfer learning across different shapes. We present a hybrid quantum PINN (HQPINN) that simulates laminar fluid flow in 3D Y -shaped mixers. Our approach combines the expressive power of a quantum model with the flexibility of a PINN, resulting in a 21% higher accuracy compared to a purely classical neural network. Our findings highlight the potential of machine learning approaches, and in particular HQPINN, for complex shape optimization tasks in computational fluid dynamics. By improving the accuracy of fluid simulations in complex geometries, our research using hybrid quantum models contributes to the development of more efficient and reliable fluid dynamics solvers.

Gaurav Sapkota, Ranjan Kumar Ghadai, Soham Das et al.

Abstract Aerospace and marine industries are constantly in search of materials that can provide good strength and durability while also being lightweight. Aluminium composites with adequate reinforcements have been proven to be effective in achieving incredible mechanical properties while also maintaining a good strength to weight ratio. Numerous studies have been done to study the various possibilities of matrix reinforcement combinations in aluminium composites. This work focuses on studying the effect of varying Cerium Oxide (CeO2) percentage in the aluminium composite on its tensile strength, hardness and corrosion resistance. CeO2 is used along with Silicon Carbide (SiC) and Multi-Walled Carbon Nanotubes (MWCNT) to develop four samples of hybrid aluminium composites with SiC and MWCNT constituting 1% and 0.1% of the composite and the weight percentage of CeO2 is varied between 1 and 2.5%. All the samples were fabricated using the modified stir casting process. The results show that the hardness and tensile strength of the composites peak when the CeO2% is at 2% while corrosion resistance only gets better with increasing reinforcement content. A significant enhancement in mechanical and physical properties of aluminium composite suggests that MWCNT is an effective hybridizing agent with SiC and CeO2 to develop aluminium composites.

E. M. Hodgson, J. McCalmont, R. Rowe et al.

Abstract The UK sixth carbon budget has recommended domestic biomass supply should increase to meet growing demand, planting a minimum of 30,000 hectares of perennial energy crops a year by 2035, with a view to establishing 700,000 hectares by 2050 to meet the requirements of the balanced net zero pathway. Miscanthus is a key biomass crop to scale up domestic biomass production in the United Kingdom. A cohesive land management strategy, based on robust evidence, will be required to ensure upscaling of miscanthus cultivation maximizes the environmental and economic benefits and minimizes undesirable consequences. This review examines research into available land areas, environmental impacts, barriers to uptake, and the challenges, benefits, and trade‐offs required to upscale miscanthus production on arable land and grassland in the United Kingdom. Expansion of perennial biomass crops has been considered best restricted to marginal land, less suited to food production. The review identifies a trade‐off between avoiding competition with food production and a risk of encroaching on areas containing high‐biodiversity or high‐carbon stocks, such as semi‐natural grasslands. If areas of land suitable for food production are needed to produce the biomass required for emission reduction, the review indicates there are multiple strategies for miscanthus to complement long‐term food security rather than compete with it. On arable land, a miscanthus rotation with a cycle length of 10–20 years can be employed as fallow period for fields experiencing yield decline, soil fatigue, or persistent weed problems. On improved grassland areas, miscanthus presents an option for diversification, flood mitigation, and water quality improvement. Strategies need to be developed to integrate miscanthus into farming systems in a way that is profitable, sensitive to local demand, climate, and geography, and complements rather than competes with food production by increasing overall farm profitability and resilience.

Dong-Wook Oh, Kwangu Kang, Jung-Hee Lee

Hydrogen has emerged as a promising carbon-neutral fuel source, spurring research and development efforts to facilitate its widespread adoption. However, the safe handling of hydrogen requires precise leak detection sensors due to its low activation energy and explosive potential. Various detection methods exist, with thermal conductivity measurement being a prominent technique for quantifying hydrogen concentrations. However, challenges remain in achieving high measurement sensitivity at low hydrogen concentrations below 1% for thermal-conductivity-based hydrogen sensors. Recent research explores the 3ω method’s application for measuring hydrogen concentrations in ambient air, offering high spatial and temporal resolutions. This study aims to enhance hydrogen leak detection sensitivity using the 3ω method by conducting thermal analyses on sensor design variables. Factors including substrate material, type, and sensor geometry significantly impact the measurement sensitivity. Comparative evaluations consider the minimum detectable hydrogen concentration while accounting for the uncertainty of the 3ω signal. The proposed suspended-type 3ω sensor is capable of detecting hydrogen leaks in ambient air and provides real-time measurements that are ideal for monitoring hydrogen diffusion. This research serves to bridge the gap between precision and real-time monitoring of hydrogen leak detection, promising significant advancements in the related safety applications.

Ruofan Wang, Ruofan Wang, Zenghui Wu et al.

Finite element analysis (FEA) is a widely used tool in a variety of industries and research endeavors. With its application to spine biomechanics, FEA has contributed to a better understanding of the spine, its components, and its behavior in physiological and pathological conditions, as well as assisting in the design and application of spinal instrumentation, particularly spinal interbody cages (ICs). IC is a highly effective instrumentation for achieving spinal fusion that has been used to treat a variety of spinal disorders, including degenerative disc disease, trauma, tumor reconstruction, and scoliosis. The application of FEA lets new designs be thoroughly “tested” before a cage is even manufactured, allowing bio-mechanical responses and spinal fusion processes that cannot easily be experimented upon in vivo to be examined and “diagnosis” to be performed, which is an important addition to clinical and in vitro experimental studies. This paper reviews the recent progress of FEA in spinal ICs over the last six years. It demonstrates how modeling can aid in evaluating the biomechanical response of cage materials, cage design, and fixation devices, understanding bone formation mechanisms, comparing the benefits of various fusion techniques, and investigating the impact of pathological structures. It also summarizes the various limitations brought about by modeling simplification and looks forward to the significant advancement of spine FEA research as computing efficiency and software capabilities increase. In conclusion, in such a fast-paced field, the FEA is critical for spinal IC studies. It helps in quantitatively and visually demonstrating the cage characteristics after implanting, lowering surgeons’ learning costs for new cage products, and probably assisting them in determining the best IC for patients.

Guangwei Liu, Wenbin Yu, Xiaodong Wang et al.

Due to the harsh actual operating environment of the permanent magnet wind turbine, it is easy to break down and difficult to monitor. Therefore, the electromagnetic characteristics identification of major fault types of large-scale permanent magnet wind turbines is studied in this paper. The typical faults of rotor eccentricity, stator winding short circuit and permanent magnet demagnetization of permanent magnet wind turbines are analyzed theoretically. The wavelet analysis algorithm is used to decompose and reconstruct the abnormal electromagnetic signal waveform band, and the characteristic frequency of the electromagnetic signal is obtained when the fault occurs. In order to verify the effectiveness of the proposed method, a 3.680MW permanent magnet wind turbine was taken as the research object. Its physical simulation model was established, and an external circuit was built to carry out field co-simulation. The results show that the motor fault type can be determined by detecting the change rule of fault characteristic frequency in the spectrum diagram, and the electromagnetic characteristic analysis can be applied to the early monitoring of the permanent magnet wind turbine fault.

Riyadh S. Almukhtar, Ali Amer Yahya, Omar S. Mahdy et al.

Due to the significant increase in heavy feedstocks being transported to refineries and the hydrocracking process, the significance of adopting an ebullated bed reactor has been reemphasized in recent years. The predictive modelling of gas hold-up in an ebullated two-phase reactor was performed using 10 machine learning methods based on support vector machine (SVM) and Gaussian process regression (GPR) in this study. In an ebullated bed reactor, the impacts of three features, namely liquid velocity, gas velocity, and recycling ratio, on the gas hold-up were examined. The liquid velocity has the most impact on the predicted gas hold-up, according to the feature significance analysis. The rotational-quadratic, squared-exponential, Matern 5/2, and exponential kernel functions integrated with the GPR models and the linear, quadratic, cubic, fine, medium, and coarse kernel functions integrated with the SVM model performed well during training and testing, with the exception of the fine SVM model, whose R² is very low. According to the R² > 0.9 and low RMSE and MAE values, the rotational-quadratic, squared-exponential, and Matern 5/2 GPR models performed the best.

Alec Passarelli, Timothy E. Rice, M. Arshad Zahangir Chowdhury et al.

Gas sensing for dimethyl sulfoxide (DMSO) based on rotational absorption spectroscopy is demonstrated in the 220–330 GHz frequency range using a robust electronic THz-wave spectrometer. DMSO is a flammable liquid commonly used as a solvent in the food and pharmaceutical industries, materials synthesis, and manufacturing. DMSO is a hazard to human health and the work environment; hence, remote gas sensing for DMSO environmental and process monitoring is desired. Absorption measurements were carried out for pure DMSO at 297 K and 0.4 Torr (53 Pa). DMSO was shown to have a unique rotational fingerprint with a series of repeating absorption bands. The frequencies of transitions observed in the present study were found to be in good agreement with spectral simulations carried out based on rotational parameters derived in prior work. Newly, intensities of the rotational absorption lines were experimentally observed and reported for DMSO in this study. Measured intensities for major absorption lines were found in very good agreement with relative line intensities estimated by quantum mechanical calculations. The sensor developed here exhibited a detection limit of 1.3 × 10¹⁵–2.6 × 10¹⁵ DMSO molecules/cm³ per meter of absorption path length, with the potential for greater sensitivity with signal-to-noise improvements. The study illustrates the potential of all electronic THz-wave systems for miniaturized remote gas sensors.

Maheswari Chinnapaiyan, Yashika Selvam, Fatma Bassyouni et al.

Nanomaterial is a rapidly growing area that is used to create a variety of new materials and nanotechnology applications from medical, pharmaceuticals, chemical, mechanical, electronics and several environmental industries including physical, chemical and biological nanoparticles are very important in our daily life. Nanoparticles with leaf extract from the healthy plant are important in the area of research using biosynthesis methods. Because of it’s used as an environmentally ecofriendly, other than traditional physical and chemical strategies. In particular, biologically synthesized nanoparticles have become a key branch of nanotechnology. The present work presents a synthesis of zinc oxide nanoparticles using an extract from the Argemone leaf Mexicana. Biosynthetic nanoparticles are characterized by X-ray diffraction (XRD), Ultraviolet visible (UV-vis) spectroscopy analysis, a Fourier Transform Infrared Spectroscopy analysis (FTIR) and a scanning electron microcopy (SEM), X-ray analysis with dispersive energy (EDAX). XRD is used to examine the crystalline size of zinc oxide nanoparticles. The FTIR test consists in providing evidence of the presence of targeted teams. UV is used for optical properties and calculates the energy of the bandwidth slot. The scanning microscope emission reveals the morphology of the surface and the energy dispersive X-ray analysis confirms the basic composition of zinc oxide nanoparticles. It is found that zinc nanoparticles are capable of achieving high anti-fungal efficacy and therefore have a high potential antimicrobial activity of ZnO NPs, like antibacterial and high antioxidant. Zinc Oxide nanoparticles from the Argemone Mexicana leaf extract have several antimicrobial applications, such as medical specialty, cosmetics, food, biotechnology, nano medicine and drug delivery system. ZnO nanoparticles are important because they provide many practical applications in industry. The most important use of nanoparticles of ZnO would be strong antibacterial and antioxidant activity with a simple and efficient biosynthesis method may be used for future work applications.

Yalin Chena, Yaqing Moua, Shilong Yeb et al.

Coal-fired electricity enterprises are caught in the dilemma of relative fixed prices and rising costs under the scenario of decarbonization. Meanwhile, soaring market-oriented coal pricing results in coal enterprises’ increasing defaults on thermal coal medium-and long-term contracts (MLC). To investigate the implementation of MLC at the micro- level, this study formalized the contractual behaviors of coal and coal-fired electricity enterprises based on the asymmetric evolutionary game. We formalized the evolving behaviors of both parties using replicator dynamics equations and proved that there were two evolutionary stabilization strategies (ESSs): compliance and coal enterprises’ unilateral default. A multi- agent-based simulation was applied to verify the evolving process of ESSs and determine the critical values of MLC design by sensitive analysis. From the simulation results, coal-fired electricity enterprises do not stop generation under the current carbon quota allocation mechanism, even if carbon emission trading increases electricity generation costs. Coal enterprises choose to “default” when the market price of coal is higher than the contracted price by 18%. However, if the original reparation is increased by 5%, the compliance rate of the coal enterprises improves. Dynamic reparations embedded in the MLC improved enforcement during the contracting period. Moreover, the proposed policy implications have practical significance for enhancing the coordinated operation of coal-electricity energy supply chains.

S. JEBAROSE JULIYANA, J. UDAYA PRAKASH

Aluminium alloy with high toughness, hardness, and impact resistance, is increasingly in demand in the aerospace and mechanical industries. Machine tools have seen rapid growth over the past two decades, but they are still not commonly used to their maximum potential. The inability to use machine tools at their peak output thresholds is at the core of the problem. Practicing engineers and researchers were intrigued by the difficulty of reaching a meticulous analysis of effective parameters. AMCs-LM5/3,6,9% ZrO2 fabricated by stir casting process are machined in Wire EDM to choose the optimum parameters by changing the Pulse on Time, Pulse off Time, Gap Voltage and Wire Feed. Achieving a good surface finish, as well as a better MRR and less kerf in the WEDM machining is of paramount importance. The experiments were conceded using the Taguchi’s L27 OA to obtain the desired effects. ANOVA determines the parameters that affect the Wire EDM, and also the relative contribution of machining parameters. The optimum levels of process parameters, for maximum MRR, minimum SR and minimum kerf were calculated. S/N ratio analysis determines the parameter that has the most impact on the response. A confirmation experiment was done for the best combination of parameters.

Hao Tian, Hongzheng Liu, Huan Ma et al.

Half-wavelength transmission can transmit large-scale renewable energy over very long distances. This paper proposes an improved steady-state voltage-control method for half-wavelength transmission systems considering large- scale wind-power transmission. First, the unique voltage characteristics of half-wavelength lines are deduced based on the distributed parameter model. In the secondary voltage-control level, reactive power-transmission limits of half-wavelength lines are introduced as another control objective except for tracing the pilot bus voltage reference. Considering the uncertainty and fluctuation of wind power, the overvoltage risk-assessment method of half-wavelength lines is presented to determine specific voltage-control strategies. Simulation results demonstrate that the proposed voltage-control method delivers superior tracking performance according to a voltage reference value and prevents the overvoltage risk of half- wavelength lines effectively in different wind-power penetrations.

Ravindra Kumar

Yaser Zarea, Saeed Parhoodeh, Leila Shahryari et al.

Zirconium oxide has found extensive applications in various industries becauseof its excellent properties such as high strength; high-temperature resistance;extraordinary wearing resistance; ionic conductivity; and corrosion resistance. Also, someProperties like high melting point, high mechanical and thermal strength, high dielectricconstant and low conductivity have introduced this material as a prominent candidate forengineering applications. In this study, zirconium oxide (ZrO2) Nano fibers wassynthesized by calcination of propoxide zirconium oxide/polyvinyl alcohol using sol-geland electrospinning methods. The morphology of the Nano fibers was verified byscanning electron microscopy (SEM) and its crystalline phase was investigated by x-raydiffraction and energy-dispersive x-ray spectroscopy (EDS). The mean diameter of theNano fibers varied in the range of 70-200 nm. XRD patterns also indicated the presenceof monoclinic and tetragonal phases in the Nano fibers calcined at 700 ℃. Results alsorevealed that this new precursor can be used in the electrospinning technique to obtainZrO2 Nano fibers with relatively high purity.