Hasil untuk "Mechanical industries"

I. B. Kantola, E. Blanc‐Betes, A. vonHaden et al.

ABSTRACT Six years after replacing a maize/soybean cropping system, perennial grasses miscanthus (Miscanthus × giganteus) and switchgrass (Panicum virgatum), and a 28‐species restored prairie increased particulate organic carbon in surface soils without increasing soil organic carbon (SOC). To resolve potential changes in the quantity and distribution of SOC, soils were resampled after seven to thirteen years to measure bulk density, carbon (C) content, and stable C isotopes to a depth of 1 m. SOC stocks increased between 1.75 and 2.5 Mg ha−1 year−1 in all perennial crops between 2008 and 2016 (nine growing seasons). Despite relatively low litter inputs and belowground biomass, the highest rate of SOC accrual was in restored prairie (2.5 Mg ha−1 year−1), followed by miscanthus (2.0 Mg ha−1 year−1) and switchgrass (1.75 Mg ha−1 year−1). The change in SOC in maize/soybean was not significant. After 2016, total SOC decreased in maize/soybean and miscanthus, resulting in slower overall rates of SOC accumulation over the full sampling period for miscanthus (0.8 Mg ha−1 year−1). The rate of SOC accumulation was greatest below 50 cm depth for restored prairie and switchgrass but in the top 10 cm for miscanthus. Stable isotope analysis showed 13C enrichment in all depths of switchgrass soils, an indication of new organic C accumulation, but mixed results in all other crops. Planting perennial crops on land formerly in an annual maize/soybean cropping system can slow or reverse soil carbon losses, with the greatest increases in SOC from species‐rich prairie.

Zhi Liu, Jinde Hao, Ronghua Yao et al.

Abstract The proton exchange membrane electrolysis cells (PEMECs) are electrochemical devices that efficiently produce high-purity hydrogen via electrical energy conversion, making them widely applicable in renewable energy storage and hydrogen infrastructure development. However, the external sodium ion (Na+) contamination can severely damage the catalyst layer and membrane in PEMEC, causing significant performance degradation. Therefore, a segmented diagnostic platform for PEMEC is developed to analyze the poisoning effects of Na+ contamination on a large scale PEMEC under various operating conditions. The results demonstrate that during the cycle test, the Na⁺ poisoning process is defined as three distinct stages of initial, sustained and stable contamination stages. An increased Na+ concentration enhances the occupations of active sites on the catalyst layer, resulting in significant voltage spike, dynamic voltage fluctuations, non-uniformity distributions of current density and temperature. Both the low water flow rate and high operating temperature improve the chemical reaction and PEMEC performance at high current density. The deionized water flushing will dissolve Na+ on the catalyst layer surface and realize 2.17% decrease in voltage at 2.0 A cm⁻2 after three cycles. This study is beneficial to consolidate the understanding of poisoning effects of sodium ion contamination in PEMEC under various operating conditions, thereby overcoming the obstacles for commercial application of green hydrogen production technology.

Gregor Papa, Rok Hribar, Gašper Petelin et al.

Abstract Background Achieving climate neutrality in cities is a major challenge, especially in light of rapid urbanization and the urgent need to combat climate change. This paper explores the role of advanced computational methods in the transition of cities to climate neutrality, with a focus on energy supply and transportation systems. Central to this are recent advances in artificial intelligence, particularly machine learning, which offer enhanced capabilities for analyzing and processing large, heterogeneous urban data. By integrating these computational tools, cities can develop and optimize complex models that enable real-time, data-driven decisions. Such strategies offer the potential to significantly reduce greenhouse gas emissions, improve energy efficiency in key infrastructures and strengthen the sustainability and resilience of cities. In addition, these approaches support predictive modeling and dynamic management of urban systems, enabling cities to address the multi-faceted challenges of climate change in a scalable and proactive way. Main text The methods, which go beyond traditional data processing, use state-of-the-art technologies such as deep learning and ensemble models to tackle the complexity of environmental parameters and resource management in urban systems. For example, recurrent neural networks have been trained to predict gas consumption in Ljubljana, enabling efficient allocation of energy resources up to 60 h in advance. Similarly, traffic flow predictions were made based on historical and weather-related data, providing insights for improved urban mobility. In the context of logistics and public transportation, computational optimization techniques have demonstrated their potential to reduce congestion, emissions and operating costs, underlining their central role in creating more sustainable and efficient urban environments. Conclusions The integration of cutting-edge technologies, advanced data analytics and real-time decision-making processes represents a transformative pathway to developing sustainable, climate-resilient urban environments. These advanced computational methods enable cities to optimize resource management, improve energy efficiency and significantly reduce greenhouse gas emissions, thus actively contributing to global climate and environmental protection.

Shreya Dave, Venkat Ram Reddy Minampati, Parth Prajapati

The abundant solar energy source provides an immense scope to create ample opportunities to produce affordable and clean energy. To utilise this energy optimally, the Ministry of New and Renewable Energy, Government of India, has launched the ‘Rooftop Solar Programme’ in 2014, aiming to achieve an installed capacity of 40 gigawatts by 2022, further extended till 2026. The present study identifies the interests and apprehensions of the respondents to install rooftop solar (RTS) panels; it analyses respondents’ perception of RTS panels and sustainable lifestyle and evaluates the government’s role in encouraging people to adopt sustainable lifestyle practices. The data are collected by applying the snowball sampling method through a structured questionnaire circulated in the 5 zones of Ahmedabad city. The citizens’ perception is collected through a 5-point Likert scale. It is found in the study that the main advantage of installing RTS panels is a reduction in electricity costs, and the main challenge is the regular maintenance of the panels. A total of 44.8% of respondents installed RTS panels as they felt that this would help them to contribute to preserving the environment. The study also reveals that the lengthy payback period of the panels (28.6% respondents) and lack of knowledge about net-metering (27% respondents) are the factors that prevent nonusers from installing the panels. The study concludes that adopting RTS panels results from awareness campaigns, government subsidies, and word of mouth. The study also concludes that both citizens and the government need each other’s cooperation to carry out a greater behaviour change programme.

Alireza Vahedi Nemani, Mahya Ghaffari, Kazem Sabet Bokati et al.

Copper-based materials have long been used for their outstanding thermal and electrical conductivities in various applications, such as heat exchangers, induction heat coils, cooling channels, radiators, and electronic connectors. The development of advanced copper alloys has broadened their utilization to include structural applications in harsh service conditions found in industries like oil and gas, marine, power plants, and water treatment, where good corrosion resistance and a combination of high strength, wear, and fatigue tolerance are critical. These advanced multi-component structures often have complex designs and intricate geometries, requiring extensive metallurgical processing routes and the joining of the individual components into a final structure. Additive manufacturing (AM) has revolutionized the way complex structures are designed and manufactured. It has reduced the processing steps, assemblies, and tooling while also eliminating the need for joining processes. However, the high thermal conductivity of copper and its high reflectivity to near-infrared radiation present challenges in the production of copper alloys using fusion-based AM processes, especially with Yb-fiber laser-based techniques. To overcome these difficulties, various solutions have been proposed, such as the use of high-power, low-wavelength laser sources, preheating the build chamber, employing low thermal conductivity building platforms, and adding alloying elements or composite particles to the feedstock material. This article systematically reviews different aspects of AM processing of common industrial copper alloys and composites, including copper-chrome, copper-nickel, tin-bronze, nickel-aluminum bronze, copper-carbon composites, copper-ceramic composites, and copper-metal composites. It focuses on the state-of-the-art AM techniques employed for processing different copper-based materials and the associated technological and metallurgical challenges, optimized processing variables, the impact of post-printing heat treatments, the resulting microstructural features, physical properties, mechanical performance, and corrosion response of the AM-fabricated parts. Where applicable, a comprehensive comparison of the results with those of their conventionally fabricated counterparts is provided.

Tamer Emre, Adnan Sözen

Abstract Energy poverty (EP), a pressing global concern, is uniquely manifested in regions like eastern Turkey due to intertwined socio-economic conditions and intricate energy consumption patterns. This study critically examines the electricity market dynamics, highlighting the direct impact on end-users, from households to entire communities facing challenges such as unauthorized consumption and waste. Our findings over 2 years period of 6 million customer invoices through 17 cities of 5 distribution companies underscore the limitations of traditional income-based measures in capturing the nuances of EP. In response, we introduce a novel metric—the power-cut index per consumer (PCPC)—spotlighting the prevalence of power interruptions due to non-payment as an actionable intervention metric. To address EP’s challenges, we present a mechanism encouraging consumers to reduce consumption, offering debt discounts as incentives. Our methodological approach, harnessing both the Monte Carlo simulation and optimization, promises flexible, actionable strategies tailored to diverse EP situations. Drawing parallels with the European Union’s energy transition efforts, this study proposes the adaptation of European frameworks to cater to Turkey’s unique landscape. By anchoring our insights in real stories of those affected by EP, we highlight the human dimension, emphasizing the urgency of stakeholder collaboration to ensure a future where energy facilitates prosperity rather than hindrance. The collective endeavors of infrastructure companies, governmental agencies, NGOs, and the public are pivotal in sculpting a brighter, equitable energy future.

Marcela Matus-Aguirre, Benoît Cosson, Christian Garnier et al.

Welding high-performance thermoplastics has gained popularity across various industries such as automotive, aerospace, and medical. Laser transmission welding (LTW) has emerged as an effective method for joining thermoplastic parts due to its precise control and high joint quality. PAEK (polyaryletherketone) are wide spreading over various industrial applications as a substitute to metals and thermosets when high durability and performance are required. Polyetherketoneketone (PEKK) is one of these PAEK and it has received less attention than PEEK until now. PEKK, being a semi-crystalline thermoplastic, requires additional care during processing due to its propensity to crystallize. This study presents both experimental and numerical investigations into LTW of PEKK molded parts, aiming to understand the influence of welding parameters and crystallinity on weld joint morphology and mechanical properties. PEKK plates, prepared in amorphous and semi-crystalline states, are subjected to LTW using a 975 nm diode laser. Material characterization confirms differences in crystallinity between the samples, which affect their thermal and optical properties, which are crucial for welding. Welding tests are conducted with varying laser power (between 75 and 95 W) and semi-transparent part thickness (2 and 4 mm). The morphology of joints is analysed. Assemblies undergo post-weld annealing treatment to examine its influence on weld crystallinity and consequent mechanical properties. Results reveal an anisotropic distribution of crystallinity within the heat-affected zone (HAZ). The depths of the molten layer (ML) and semi-crystalline layer (scL) vary with laser power and assembly type. A notable decrease in weld strength with laser power is highlighted, while annealing leads to enhanced crystallinity and improved weld strength. Despite variations, high weld strengths are achieved with annealing. Computational modelling elucidates the complex interplay between laser irradiation, temperature distribution, and crystallization kinetics observed experimentally. Overall, this comprehensive investigation provides valuable insights into optimizing LTW parameters for PEKK parts.

Eugenia Obidiegwu, Henry E. Mgbemere, Arhuere O. Akporehe

This study investigated the physical, mechanical and thermal characteristics of insulating refractory bricks produced from Nigerian clay blended with melon seed husk. The aim is to reduce the cost of production which arises from importation. This is due to lack of high-quality domestic insulating refractory bricks in most high temperature industries in Nigeria. The test samples were produced by mixing clay and melon seed husk having grain sizes of 212 - 300 μm. The samples were oven dried and fired at temperatures 950℃ to 1150℃ at 50℃ intervals. Physical, mechanical, thermal tests, chemical compositions, Mineralogical and Microstructural analysis were conducted. The results showed that, clay with 25 and 30 wt.% melon seed husks possessed the required refractory properties with cold crushing strength above the recommended ASTM Standard of 1000 kN/m2.

Efstathios E. Michaelides

Abstract The substitution of fossil fuels, especially coal, with renewable energy is a crucial step for the CO2 emissions reduction and the avoidance of Global Climate Change. The electric power generation industry is the first economic sector that will have to transition to renewable energy. However, wind and solar energy, the two most abundant renewable energy forms, are not dispatchable. The high penetration of these renewables in the energy market will create a demand–supply mismatch, which can only be alleviated with large-scale energy storage. This paper uses the case of Texas—a state that generates and consumes more electricity than several large, industrialized nations—to quantitatively examine the required infrastructure for the decarbonization of the electricity generation industry, while satisfying the current electric power demand in the State. Among the parameters that are examined are: the additional solar and wind capacity; the necessary energy storage infrastructure; the energy dissipation in the storage/regeneration process; and the effect of decarbonization on the cost of electricity and the welfare of the citizens. The computations show that the technology is available for the transition to a decarbonized electric power sector but requires significant investment in new wind and photovoltaic units as well as substantial energy storage. This would increase the electricity prices by a factor between 2.9 and 3.7 and, would have a disproportionate impact on the citizens in the lower income brackets.

Ahmad Khalf Alkhawaldeh, Ahmed Mahdi Rheima, Mustafa M. Kadhim et al.

With the rapid development of nanotechnology in the recent decade, novel DNA and RNA delivery systems for gene therapy have become available that can be used instead of viral vectors. These non-viral vectors can be made of a variety of materials, including inorganic nanoparticles, carbon nanotubes, liposomes, protein and peptide-based nanoparticles, as well as nanoscale polymeric materials. They have as advantages over viral vectors a decreased immune response, and additionally offer flexibility in design, allowing them to be functionalized and targeted to specific sites in a biological system with low cytotoxicity.gene therapy keeps hopes a life for the treatment of a wide range of diseases such as cancer, nano particles are now known as promising carriers for the effective and safe vectors of genes to specific cells or tissues. This could provide alternative therapies for conventional approaches that use viruses as gene carriers. The expression of genetic material such as DNA, RNA into cells and tissues has raised considerable hopes for therapeutic and diagnostic purposes. But getting nucleic acids into the cell also faces challenges. These challenges are less for non-virus carriers as a gene and drug vectors method than for viral or free vectors and are therefore considered less risky and more appropriate. of expanding nonverbal nano carriers, we will look at a few of these nano carriers, penicillin, PEI, PLGA, silica, block copolymer, Quantum dot, gold nano particles, and common carbon nano tubes. Problems include the use of nano particles such as polymer nano particles, liposomes, solid lipid particles, in targeted gene vectors will be investigated. Gene-based therapy is the intentional modulation of gene expression in specific cells to treat pathological conditions. This modulation is accomplished by introducing exogenous nucleic acids such as DNA, mRNA, small interfering RNA (siRNA), microRNA (miRNA) or antisense oligonucleotides. Given the large size and the negative charge of these macromolecules, their delivery is typically mediated by carriers or vectors. In this Review, we introduce the biological barriers to gene delivery in vivo and discuss recent advances in material sciences, nanotechnology and nucleic acid chemistry that have yielded promising non-viral delivery systems, some of which are currently undergoing testing in clinical trials. The diversity of these systems highlights the recent progress of gene-based therapy using non-viral approaches.

Katarzyna Świątek, Maciej P. Olszewski, Andrea Kruse

Abstract 5‐hydroxymethylfurfural (HMF) is the object of extensive research in recent times. The challenge in the industrial production of HMF is the choice of cheap, hexose feedstock. This study compares continuous HMF synthesis from hexoses—fructose and glucose, and biomass—Miscanthus × giganteus and chicory roots. The experiments were conducted in technical‐scale biorefinery (TRL 6/7). In the first stage, optimal conditions for the production of HMF from hexoses were selected using sulfuric acid as a catalyst in an aqueous medium. The following conditions were chosen for fructose: temperature of 200°C, the reaction time of 18 min, and pH = 2, and for glucose: 210°C, 18 min, and pH = 3. Under these conditions, the HMF yield was 56.5 mol% (39.6 wt.%) from fructose and 18.1 mol% (12.6 wt.%) from glucose. From the biomass, the HMF yields were 36.7 and 16.2 wt.% for miscanthus and chicory roots, respectively. Some results from the conversion of biomass solutions are unexpected and show a need for further investigations. This work has demonstrated the capacity to produce HMF from biomass as part of an environmentally friendly process in a biorefinery. Further research in this field and process optimization will be a step forward in the sustainable production of bioplastics.

Qiang Hu, Wenhui Liu, Changping Tang et al.

2519A aluminum alloy thick plate is a promising structural material in the field of military industries, owing to its low density, high tensile strength and excellent ballistic performance. However, the nonuniformly distributed microstructure along the thickness direction of this alloy leads to delamination cracks, which restrict its further application in light armor fields. In order to understand the mechanism of delamination cracking along the thickness direction, the effect of the microstructure on the mechanical properties of 2519A aluminum alloy in the thickness direction was investigated. The results show that the elongation and critical stress intensity factor values (Δ<i>K_cr</i>) of the alloy in the thickness direction are 45.8% and 44.1% lower than the values in the rolling direction, respectively. The low mechanical properties of the alloy may be due to the short distance between the second phase, the weak binding force of grain boundaries and the disharmonious deformation caused by the inhomogeneous distribution of the microstructure. This study provides a basis for improving the mechanical properties and delamination cracking of the alloy along the thickness direction.

MOHAMMED KHADRAWY, Aliaa Abdelfatah, Mahmoud Ahmadein et al.

The escalated concern in duplex stainless steels by industries is due to their best mechanical and corrosion resistance properties. In this work, the mechanical properties welding duplex stainless steel 2205 has studied. Joints were made using the GTAW process with different fillers: duplex ER 2209 and austenitic filler ER 312. There is a similarity in the microstructure which is obtained between with the duplex ER 2209 filler to the duplex 2205 base material, but the joints produced with the austenitic fillers cause a increase of the ferrite(δ) to austenite(γ) phase ratio. In order to evaluate the influence of the fillers on the weld, the mechanical properties by impact , tensile test and the hardness test. The phase imbalance produced for the different fillers causes variation of the mechanical properties. Without getting any detrimental changes in the mechanical properties, by using different filler metals, has addressed in this work .while, ER 312 had the advantage in hardness , tensile, impact test and ferrite percent.

D. Abboud, J. Antoni, S. Sieg-Zieba et al.

Dmytro Mishchuk, Yevhen Mishchuk, Ievgenii Gorbatyuk

Задачі оптимізації режимів руху механічних систем, зокрема роботів та маніпуляторів, є актуальною в контексті сучасного розвитку суспільства та машинобудування. Роботи і маніпулятори здатні автономно виконувати складні задачі по заданих програмах керування, що значно знижує вартість виконуваних ними робіт. Алгоритми оптимальних переміщень складових елементів роботів і маніпуляторів дозволяють реалізовувати складні траєкторії переміщень їхніх робочих органів з прогнозованими енерговитратами, точністю позиціювання, швидкодією. Пошук оптимальних режимів руху є складною і не однозначною задачею, що вимагає точного формулювання функції оптимізації, рівнянь обмежень та методів визначення оптимальних законів, які б задовольняли критерії поставленої оптимізаційної задачі. Одним із шляхів вирішення таких складних задач є евристичні методи перебору варіантів розв’язку на обмеженій площині, зокрема одним з таких є методів рою частинок.  В даному досліджені проаналізовано класичний метод рою частинок для пошуку оптимального режиму руху стріли маніпулятора за однієї з узагальнених координат. Цільовою функцією оптимізації вибрано «енергію» прискорень механічної системи, а пошук оптимального закону переміщення здійснюється із застосуванням полінома четвертого порядку. Проведене теоретичне дослідження показало, що метод рою частинок може бути застосований для пошуку оптимальних законів руху, проте при роботі з даним методом необхідно модернізувати алгоритм визначення його складових, зокрема швидкості переміщення частинок та їх корегувальних коефіцієнтів. При визначенні оптимальних законів руху маніпулятора методом рою в даному дослідженні застосовується підхід, де прийнято, що час є дискретним, а значення цільової функції визначалося лише в прийнятих точках дискретизації часу.

Zareef Askary, Ravinder Kumar

Erfan Hosseini, Zhongwei Chen, Mohammad Sarmadivaleh et al.

Abstract Seawater has been widely used as an injection fluid for maintaining pressure in sandstone and carbonate reservoirs. In the literature related to EOR research, it was noted that diluted seawater (low-salinity water) can highly improve recovery due to the specific ions (such as Ca2+, Mg2+, and SO4 2−). Such conclusions lead to the application of “Smart Water” in which changing the ion composition of injected water alters wettability and enhances recovery. Although many theories have been established to explain the mechanism of this phenomenon, almost all of them are limited to sandstone rocks, and the impact of smart water on carbonated reservoirs has rarely been explored. This study experimentally investigates the impact of the injection of high- and low-salinity and smart water on the change of wettability and recovery improvement in an Iranian South oil reservoir. Two different sets of experimental work were conducted. In the first set of experiments, the effect of formation water, diluted formation water (from 223,969 to 5000 ppm and 2000 ppm), seawater (initially 51,400 ppm), and diluted seawater on wettability alteration is investigated by monitoring the contact angle and relative permeability variation. The results showed that dilution of seawater to 2000 ppm has the most impact on wettability alteration. The relative permeability changed, and the contact angle decreased by a significant value of 100°, and recovery increased by about 71%. In the second set, the effect of ion change on the result was studied. For this purpose, the sulfate ion of diluted seawater (2000 ppm) is substituted by phosphate ion (H2PO4 −). The results show the wettability alteration similar to the sulfate one. This study sheds light on the possible mechanism of wettability alteration in the carbonate reservoir, and the result will help to design a better low-salinity injection scenario.

Francisco A. R. Lahr, Marta C. de J. A. Nogueira, Victor A. De Araujo et al.

ABSTRACT Over the years, the species of eucalyptus has become a multipurpose raw material. In addition, the most relevant aspect of the use for various purposes is related to the production of a high quality wood, coming from short duration plantations, which is fundamental to the current demand of the industries. However, its use in civil construction has not yet reached a level of importance, due to the low knowledge of many of its resistance properties and the consequent popular fear in the use of reforestation woods, in particular the Eucalyptus grandis. This research investigated its main mechanical properties, aiming to reinforce its constructive applications in wood structures. For this, two physical properties and fourteen mechanical properties, in two different moisture conditions of the samples were evaluated, according to the norm NBR 7190 (1997). In the first moisture content, the samples were stabilized at 30%, while the second level considered the content of 12%. It was obtained 3580 determinations for the sixteen properties. From the 14 mechanical properties, only 7 had significant increases with the moisture reduction (30% to 12%), consisting of the rupture modulus in the parallel and normal compressions, normal traction and static bending; modulus of elasticity in normal compression and static bending and in shear strength.

Yanling Lin, Zhaohong Bie, Aici Qiu

The world is witnessing increasing frequency of extreme events. The power system is the backbone critical infrastructure of our economy and is under treat of such events. The resilient power system is intended to cope with low probability, high risk extreme events including extreme natural disasters and man-made attacks. Realizing resilience in the power system has been an unprecedented mission. Equipped with today’s smart grid technologies, power system can be rendered more resilient by the strategies taken before, during and after a disruptive event erupts. Based on a thorough review of existing works, we present the most-investigated problems and solving measures according to their application stage. In the preparation stage, innovative planning frameworks considering disaster scenarios are discussed; after the event, the system can alter the topology and integrate resource allocation to alleviate load shedding. The characteristics of different disasters are investigated to facilitate enhancing resilience. The review provides a summary of resilience strategies in the power system and can shed light to future research and application. Keywords: Power system, Resilience, Critical infrastructure, Extreme event, Natural disaster

Bohács K., Faitli J., Bokányi L. et al.

Due to the special characteristics of zeolites, they can be applied in a very wide range of industries, i.e. agricultural, environmental or water treatment purposes. Generally, high added value zeolite products are manufactured by micro- or nanogrinding. However, these processes require high energy input and cause significant wearing of the mill parts. Therefore, the optimization of zeolite grinding, as well as the control of its properties are of a great importance. In the present paper a Hungarian natural zeolite was mechanically activated in stirred media mill for various residence times in distilled water, meanwhile the particle size distribution and the grinding energy were measured. Additionally, on-line tube rheometer was used to study the rheology of the suspension during the grinding process. The particle interaction and the suspension aggregation stability were detected by zeta-potential measurements. Structural changes due to the mechanical activation process were monitored by FTIR. It was found that the material structure of the zeolite, as well as the rheological behaviour of the zeolite suspension and its aggregation stability had been altered due to the mechanical activation in the stirred media mill. It can be concluded that the zeolite product properties can be modified by mechanical activation in order to produce a high added value tailored material.