Hasil untuk "Mechanical industries"

F. Meyer-Krahmer, U. Schmoch

N. Baddoo

K. Katnam, L.F.M. da Silva, T. M. Young

Hang Z. Yu, Mackenzie E. Jones, G. Brady et al.

Abstract Beam-based processes are popularly used for metal additive manufacturing, but there are significant gaps between their capabilities and the demand from industry and society. Examples include solidification issues, anisotropic mechanical properties, and restrictions on powder attributes. Non-beam-based additive processes are promising to bridge these gaps. In this viewpoint article, we introduce and discuss additive friction stir deposition, which is a fast, scalable, solid-state process that results in refined microstructures and has flexible options for feed materials. With comparisons to other additive processes, we discuss its benefits and limitations along with the pathways to widespread implementation of metal additive manufacturing.

Wenya Li, A. Vairis, M. Preuss et al.

Dalia Mahmoud, M. Elbestawi

A major advantage of additive manufacturing (AM) technologies is the ability to print customized products, which makes these technologies well suited for the orthopedic implants industry. Another advantage is the design freedom provided by AM technologies to enhance the performance of orthopedic implants. This paper presents a state-of-the-art overview of the use of AM technologies to produce orthopedic implants from lattice structures and functionally graded materials. It discusses how both techniques can improve the implants’ performance significantly, from a mechanical and biological point of view. The characterization of lattice structures and the most recent finite element analysis models are explored. Additionally, recent case studies that use functionally graded materials in biomedical implants are surveyed. Finally, this paper reviews the challenges faced by these two applications and suggests future research directions required to improve their use in orthopedic implants.

José A. Tamayo, Mateo Riascos, C. A. Vargas et al.

Additive Manufacturing (AM) or rapid prototyping technologies are presented as one of the best options to produce customized prostheses and implants with high-level requirements in terms of complex geometries, mechanical properties, and short production times. The AM method that has been more investigated to obtain metallic implants for medical and biomedical use is Electron Beam Melting (EBM), which is based on the powder bed fusion technique. One of the most common metals employed to manufacture medical implants is titanium. Although discovered in 1790, titanium and its alloys only started to be used as engineering materials for biomedical prostheses after the 1950s. In the biomedical field, these materials have been mainly employed to facilitate bone adhesion and fixation, as well as for joint replacement surgeries, thanks to their good chemical, mechanical, and biocompatibility properties. Therefore, this study aims to collect relevant and up-to-date information from an exhaustive literature review on EBM and its applications in the medical and biomedical fields. This AM method has become increasingly popular in the manufacturing sector due to its great versatility and geometry control.

K. Zia, S. Tabasum, Muhammad Faris Khan et al.

Nazila Oladzadabbasabadi, Abdorreza Mohammadi Nafchi, Fazilah Ariffin et al.

Current environmental concerns fostered a strong interest in extracting polymers from renewable feedstocks. Chitosan, a second most abundant polysaccharide after cellulose, may prove to be a promising green material owing to its renewability, inherent biodegradablity, natural availability, non-toxicity, and ease of modification. This review is intended to comprehensively overview the recent developments on the isolation of chitosan from chitin, its modification and applications as a reinforcing candidate for food packaging materials, emphasizing the scientific underpinnings arising from its physicochemical properties, antimicrobial, antioxidant, and antifungal activities. We review various chitosan-reinforced composites reported in the literature and comprehensively present intriguing mechanical and other functional properties. We highlight the contribution of these mechanically robust and responsive materials to extend the shelf-life and maintain the qualities of a wide range of food commodities. Finally, we assess critical challenges and highlight future opportunities towards understanding the versatile applications of chitosan nanocomposites.

Vlad Mihalca, Andreea Diana Kerezsi, A. Weber et al.

Food packaging is an area of interest not just for food producers or food marketing, but also for consumers who are more and more aware about the fact that food packaging has a great impact on food product quality and on the environment. The most used materials for the packaging of food are plastic, glass, metal, and paper. Still, over time edible films have become widely used for a variety of different products and different food categories such as meat products, vegetables, or dairy products. For example, proteins are excellent materials used for obtaining edible or non-edible coatings and films. The scope of this review is to overview the literature on protein utilization in food packages and edible packages, their functionalization, antioxidant, antimicrobial and antifungal activities, and economic perspectives. Different vegetable (corn, soy, mung bean, pea, grass pea, wild and Pasankalla quinoa, bitter vetch) and animal (whey, casein, keratin, collagen, gelatin, surimi, egg white) protein sources are discussed. Mechanical properties, thickness, moisture content, water vapor permeability, sensorial properties, and suitability for the environment also have a significant impact on protein-based packages utilization.

Damayanti Damayanti, Latasya Adelia Wulandari, Adhanto Bagaskoro et al.

The fashion industry contributes to a significant environmental issue due to the increasing production and needs of the industry. The proactive efforts toward developing a more sustainable process via textile recycling has become the preferable solution. This urgent and important need to develop cheap and efficient recycling methods for textile waste has led to the research community’s development of various recycling methods. The textile waste recycling process can be categorized into chemical and mechanical recycling methods. This paper provides an overview of the state of the art regarding different types of textile recycling technologies along with their current challenges and limitations. The critical parameters determining recycling performance are summarized and discussed and focus on the current challenges in mechanical and chemical recycling (pyrolysis, enzymatic hydrolysis, hydrothermal, ammonolysis, and glycolysis). Textile waste has been demonstrated to be re-spun into yarn (re-woven or knitted) by spinning carded yarn and mixed shoddy through mechanical recycling. On the other hand, it is difficult to recycle some textiles by means of enzymatic hydrolysis; high product yield has been shown under mild temperatures. Furthermore, the emergence of existing technology such as the internet of things (IoT) being implemented to enable efficient textile waste sorting and identification is also discussed. Moreover, we provide an outlook as to upcoming technological developments that will contribute to facilitating the circular economy, allowing for a more sustainable textile recycling process.

P. Postweiler, D. Rezo, M. Engelpracht et al.

Abstract Limiting anthropogenic climate change to below 2 °C requires substantial and rapid reductions in greenhouse gas emissions. Additionally, carbon dioxide removal technologies are essential to compensate for hard-to-abate emissions and counteract overshooting the earth’s carbon budget. One prospective technology is direct air carbon capture and storage (DACCS), but its energy intensity and costs limit large-scale deployment. Flexible DACCS operation seems promising for cost reduction but yet remains underexplored. This study explores the economic benefits of flexible operation of adsorption-based DACCS, considering fluctuations in both electricity prices and greenhouse gas emissions from the electricity supply. To increase the feasibility of flexible DACCS operation, the typical steam-assisted temperature vacuum swing adsorption cycle is enhanced by introducing two break phases and variable air and steam mass flows during adsorption and desorption. The benefits of flexible operation are comprehensively evaluated using a DACCS system model integrating a detailed dynamic process model with life-cycle greenhouse gas emissions and economic data. The flexible operation allows each cycle to be adjusted to optimally address the time-varying greenhouse gas emissions and costs from electricity supply. A rolling horizon algorithm combined with particle swarm optimization is used to optimize the DACCS cycles in flexible operation mode over one week. The case study focuses on the future German power grid and a DACCS system using amine-functionalized sorbents. Results indicate that flexible DACCS operation can significantly reduce net carbon removal costs by up to 20 % compared to a steady-state operation. These findings highlight the potential of flexible DACCS operation to support carbon neutrality efforts by enabling cost-effective carbon dioxide removal through integration with volatile renewable energy systems.

Rafaella Canessa, Rebecca Peer, Manuel Wetzel et al.

The transition to a decarbonised energy system presents a significant challenge for New Zealand, particularly as it strives to meet its net-zero emissions target by 2050. Existing peer-reviewed studies on New Zealand’s energy transition are scarce and lack the necessary spatial and temporal resolution to accurately model the integration of renewable energy, green hydrogen production, and storage needs. To address these gaps, this study introduces REMix-NZ, a high-resolution energy system optimisation model tailored to New Zealand. REMix-NZ captures hourly time steps, geographic specificity, and diverse energy technologies to analyse the country’s future energy pathways, including power system expansion and green hydrogen export scenarios. Through the use of REMix-NZ and scenario analysis, it is possible to evaluate future energy capacities, storage requirements, and the impact of hydrogen exports for the milestone years 2030 and 2050. Results show that New Zealand needs to increase its installed power generation capacity by up to 13 times by 2050, with solar photovoltaics providing over 65% of electricity. Additionally, approximately 650 GWh of new storage capacity, mostly batteries and hydrogen storage, will be required. Hydrogen exports to the Pacific Islands in the form of e-fuels are feasible with an additional capacity of around 11%, demonstrating an opportunity for international energy trade.

Paschalis Charalampous

This paper presents a numerical sketch-based methodology to achieve optimal product design solutions, bridging the gap between initial conceptual sketches and advanced engineering analyses. The proposed approach enables the transformation of simple hand-drawn sketches into digital models suitable for complex computational simulations and design optimization. Using computer vision algorithms, sketches are processed to generate digital design components that serve as inputs for Finite Element Analysis (FEA). In order to further enhance the overall design process, topology optimization (TO) is also performed, iteratively refining the geometry to achieve optimal material distribution for improved structural performance. Additionally, Adaptive Mesh Refinement (AMR) techniques are applied to ensure computational efficiency and accuracy by dynamically refining the mesh in regions of high complexity or stress concentration. The synergy of sketch-based modeling, FEA, TO, and AMR demonstrates significant potential in reducing design cycles while maintaining high-performance standards. Finally, it should be noted that the proposed pipeline consists of a fully automated procedure, hence it could reduce the learning curve for the designers, enabling companies to onboard employees faster and integrate advanced design techniques into their workflows without extensive training. The above-mentioned modules render the introduced approach particularly suitable for applications in product design development that can be utilized in several industries like mechanical, manufacturing, and furniture.

Si Xu, Wanli Cheng, Huanan Li et al.

ABSTRACT Metabolic engineering of Saccharomyces cerevisiae has enabled xylose‐fermenting yeast strains. However, the bioavailability dilemma of xylose has become the core bottleneck restricting the economy of lignocellulose. This study investigates the overexpression of the transketolase gene (TKL1) in the pentose phosphate pathway to enhance xylose utilization efficiency during mixed sugar fermentation. We initially characterized the effects of different carbon and nitrogen sources on xylose consumption and ethanol production. The recombinant yeast strain INVSc‐xylA‐Xltr1p‐TKL1 demonstrated significant improvements in xylose utilization. In a xylose‐only medium (SCX) with organic nitrogen, the strain consumed 1.54 g/L of xylose over 120 h, while in a mixed glucose and xylose medium, xylose consumption reached 3.01 g/L, reflecting increases of 52.4% and 16.2% compared with the control, respectively. With inorganic nitrogen, the strain consumed 1.3 g/L of xylose in a SCX medium and 2.69 g/L in a mixed glucose‐xylose medium, corresponding to increases of 13% and 24.5% compared with the control group, respectively. Under optimal conditions, the recombinant strain achieved a sugar‐to‐ethanol conversion rate of 0.43 g/g, yielding 84.3% and 93.5% of the theoretical ethanol production for glucose and xylose, respectively. Furthermore, qPCR analysis revealed that the expression level of the xylose isomerase (xylA) gene in INVSc‐xylA‐Xltr1p‐TKL1 was significantly upregulated, doubling that of the control. This enhanced expression correlated with reduced xylulose accumulation, suggesting alleviation of xylA repression. These findings demonstrate that transketolase overexpression enhances the co‐utilization of glucose and xylose, improving bioethanol production efficiency.

Z. Li, Yi Wang, Ke-sheng Wang

Zhuoya Tong, Xiaobo Zhu

Lithium-ion batteries (LIBs) is now a cornerstone technology to curb carbon emission by enabling electric vehicles and grid-scale energy storage. However, LIBs are highly materials-intensive, the cost and availability of the key materials, especially the lithium-containing cathode materials, are critical for the goal of decarbonization. High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cobalt-free cathode material to cater to the surging demand for low-cost and high-energy-density LIBs. In this paper, the advantages of LNMO are quantified in terms of performance and sustainability, then the growing interest in the research and development (R&D) of LNMO is assessed by analyzing 559 related patents registered across 22 authorities. The analysis paints a comprehensive picture, including geographical distribution of patenting activities, major developers, and influential patents. Furthermore, the patents are categorized into four key innovation directions. A gradual shift from materials engineering to electrolyte design indicates that the development of novel high-voltage compatible electrolytes is expected to unlock LNMO for next-generation, sustainable, and high-performance batteries.

Abdulrasheed Isah, Michael O. Dioha, Ramit Debnath et al.

Abstract Background Achieving climate targets will require a rapid transition to clean energy. However, renewable energy (RE) firms face financial, policy, and economic barriers to mobilizing sufficient investment in low-carbon technologies, especially in low- and middle-income countries. Here, we analyze the challenges and successes of financing the energy transition in Nigeria and Brazil using three empirically grounded levers: financing environments, channels, and instruments. Results While Brazil has leveraged innovative policy instruments to mobilize large-scale investment in RE, policy uncertainty and weak financing mechanisms have hindered RE investments in Nigeria. Specifically, Brazil’s energy transition has been driven by catalytic finance from the Brazilian Development Bank (BNDES). In contrast, bilateral agencies and multilateral development banks (MDBs) have been the largest financiers of renewables in Nigeria. Policy instruments and public–private partnerships need to be redesigned to attract finance and scale market opportunities for RE project developers in Nigeria. Conclusions We conclude that robust policy frameworks, a dynamic public bank, strategic deployment of blended finance, and diversification of financing instruments would be essential to accelerate RE investment in Nigeria. Considering the crucial role of donors and MDBs in Nigeria, we propose a multi-stakeholder model to consolidate climate finance and facilitate the country’s energy transition.

Ji Qi, Haoqi Qian

Abstract The failure of the USD 100-billion climate finance pledge under the United Nations Framework Convention on Climate Change (UNFCCC) could be attributed to a series of reasons: the inconsistent rules, the ambiguity of accountability issues, the political and economic motivations of donor countries, the weak governance capability of developing countries, etc. In addition to the predicament of climate finance commitments made by industrialized nations, South-South cooperation is becoming an important supplemental approach and is acknowledged by the Paris Agreement as an essential means of support. Through studying a broad set of literature on climate finance governance, the study aims to provide a clear picture of the current muddle in climate finance and China’s new role in the architecture. We do this by first looking into the disjointed system of reporting and accounting standards for climate finance as well as what causes the international climate finance gap. On the one hand, the self-interests and geopolitical concerns of donor countries led to considerable challenges to distributive justice in climate finance allocation. On the other hand, climate finance from rich countries has yet to make a substantial dent in enhancing developing countries’ resilience to climate change. Finally, we argue that China-led climate-related development assistance and South-South cooperation on climate change has a tremendous potential for vulnerable countries to realize their climate action priorities and address the climate injustice.

Abhishek Sadananda Madival, Deepak Doreswamy, Raviraj Shetty

The biodegradable characteristics and abundant availability of the fiber sources have gained the attention of various industries to produce natural fiber-based composites. As a sustainable alternative to the non-biodegradable fiber-based products, the natural composites provide a viable solution to reduce the environmental pollution caused by synthetic materials. This study developed rice straw particle (RSp) and Furcraea foetida (FF) fiber reinforced hybrid composite and investigated its physical and mechanical properties. The addition of 15 wt.% of RSp reduced the density of the test samples by 41.87% and its water absorption (WA) increased with the increase in fiber concentration. The composite with 5 wt.% and 15 wt.% of RSp showed maximum tensile strength (σt: 29.45 MPa) and modulus (σtm: 3.67 GPa), respectively. At 15 wt.% of RSp, the maximum flexural strength (σf: 43.12 MPa) and modulus (σfm: 2.09 GPa) was achieved and at 10 wt.% of RSp showed the highest impact strength (σi: 101.01 J/m). The σt (40.21%) and σf (7.76%) of the RSp reinforced composite were improved by the hybridization of FF (20 wt.%) fiber reinforcement.