Engine Components Research Articles

Impact of off-road engine electrification through EGR pumping on CO2, soot, and NOx emissions reductions during steady-state operating conditions

Off-road vehicles are emphasizing brake thermal efficiency improvements to meet upcoming diesel emission standards set by the California Air Resources Board (CARB), aiming for enhanced engine and vehicle component efficiency. CARB is implementing regulations demanding a 90% reduction in oxides of nitrogen (NOx) emissions compared to current EPA Tier 4 standards, extending to off-highway vehicles by 2031. The experimental study described in this paper investigated how high-efficiency turbocharging (HET) and electric 48 V EGR pumping (EGRP) enable improved fuel efficiency in a 13.6 L off-road Diesel engine during steady-state operation. The integration of a 48 V EGR Pump enables the complete use of the high-efficiency turbo, encompassing both fuel reduction and NOx mitigation, at reduced engine delta pressure (exhaust—intake manifold pressure). Fuel consumption reductions in excess of 8% at low-speed/high-loads, nearly 5% on the torque curve at 1200 rpm, and 1.6%–3.1% in high-speed/high-load scenarios were demonstrated. NOx levels were generally similar to or lower than the baseline. Soot emissions remained comparable to or lower than the baseline. Open cycle efficiency (OCE) was improved across all points studied. Closed cycle efficiency improved under specific conditions, particularly at low-speed/high-load scenarios for which advanced injection timing could be used as a result of improved EGR flow control with the EGR pump. The OCE improvements were driven by reduced pumping work, with primary attribution to the high-efficiency turbocharger. The EGR pump played a pivotal role in maintaining engine-out NOx levels, especially under conditions where the conventional high-pressure EGR system would have been limited due to reduced pressure differentials between the intake and exhaust manifold (as a result of the high-efficiency turbocharging).

Expanding the Capability of a Legacy Combustion Flame Tube to Test High-Temperature Engine Materials in Relevant Environments

Abstract New materials and component designs are needed to advance gas turbine engine technology and provide the performance and efficiency needs for future applications. In order to advance these materials, testing in combustion environments is a critical step prior to engine testing. In this work, we detail the design and the fabrication of a materials test sector in a flame tube combustor facility. The facility simulates a combustion environment similar to that experienced by components in gas turbine engines. The flow regime is characterized by a combination of high-temperature, high-heat flux, and high-velocity that components experience in gas turbine engines. Exposure of components in this facility allows for the study of combined environmental effects and the impact on both coating and substrate durability. The test facility may operate across a wide range of pressures from 275 to 400 psig (1896–2758 kPa) and an air flowrate of 5 lb/s (2.27 kg/s). While combustion gas temperature is expected in excess of 3000 °F (1649 °C), 900 °F (482 °C) cooling air may be supplied to the backside of components or test articles. The flame tube combustor was previously used to evaluate fuel injectors and combustion products, and the new test configuration will also allow for materials exposure to complex, engine-like conditions. The interior of the test section was additively manufactured from GRCop-84 and cryogenically fit and brazed to a stainless-steel 304 housing. The use of a copper liner minimizes welds and, with active cooling, is expected to provide better durability over traditional hardware using stainless-steel or Inconel with a ceramic liner. The test section has two opposing 9.5 in × 3.125 in (241 mm × 80 mm) removable windows that can accommodate articles up to 3.5 in (89 mm) tall. This modular design allows for custom platforms to hold coupons, panels, or airfoil shapes to be tested with minimal re-engineering or fabrication. The bolted joint and sealing remains consistent, so any new testing only needs to work within the existing design footprint. This paper will provide an overview of the facility capabilities, design considerations, as well as thermal and structural analysis of the hardware. Future testing of ceramic matrix composite (CMC) airfoils and advanced environmental barrier coatings (EBCs) will also be discussed.

Structure and mechanical properties of consolidated billets from recycled chip wastes of cast metal matrix composites of the Al-Si-SiC system

This study examines the structure and mechanical properties of billets produced via hot pressing from ball-milled chips of Al-Si-SiC metal matrix composites. The chips, derived from cast composites, were subjected to high-energy ball milling to obtain powder, which was then consolidated by hot pressing at 450 °C. The findings reveal that machining reduces the average size of SiC particles from 41.9 to 12.9 µm, and ball milling further reduces it to 5.9 µm. Powder-pressed billets exhibited a more homogeneous SiC distribution and showed ∼1.9 times higher hardness than the cast material, while chip-pressed billets showed only a ∼13 % increase. Compression tests indicated the highest yield strength of 333 ± 7 MPa in powder-pressed samples, compared to 225 ± 6 MPa in the cast state and 143 ± 26 MPa in chip-pressed samples. However, powder-pressed samples had lower ductility (∼3 %) than cast and chip-pressed samples. The influence of hot pressing temperature (350–500 °C) on the structure and mechanical properties was also explored, showing that higher temperatures improve silicon distribution but slightly reduce hardness and yield strength. Recycled composite materials from chip waste are promising for producing consolidated billets, especially for small-sized components in machinery and instrument engineering.

Hardfacing of GX40CrNiSi25-20 cast stainless steel with an austenitic manganese steel electrode

Abstract To enhance the wear and corrosion resistance of engineering components, various surface modification techniques have been devised. Among these, arc welding processes employing specialized electrodes offer relatively straightforward methods with low production costs for hardfacing applications. This paper focuses on the hardfacing process using pulsed current arc welding to reinforce cast austenitic steel structural components, aiming to prolong their lifespan. Typically, hardfacing coatings utilize Fe, Ni, and Co-based alloys. Among these, Fe-based alloys, such as manganese austenitic alloys employed in our experiments, are favored for their robust mechanical work hardening capacity, resulting in significant hardness enhancements (from 186–219 HV5 in the as-deposited layer to 468–492 HV5 after mechanical work hardening) under intense wear and impact conditions. The innovation of the hardfacing process developed in this study lies in utilizing a universal TIG source adapted for manual welding with a covered electrode in pulsed current mode. This hardfacing technique can be applied to both worn components in operation and new ones before being put into service, thereby ensuring long-term durability and reducing maintenance costs.

Impact of Blowing and Density Ratio on the Film Cooling and Heat Transfer in an Aggressive Turbine Center Frame

Abstract It was shown in the previous study that the aft purge flows from the last stage of the high-pressure turbine (HPT) have a significant film cooling potential in the downstream turbine center frame (TCF) (Jagerhofer et al., 2023, “Heat Transfer and Film Cooling in an Aggressive Turbine Center Frame,” ASME J. Turbomach., 145(12), p. 121012). The TCF is a stationary duct that guides the flow from the HPT outlet to the low-pressure turbine (LPT) inlet and is the third most thermally loaded engine component. This article investigates the impact of different purge-to-mainstream blowing and density ratios on the film cooling effectiveness and the heat transfer coefficient in the TCF. The experiments were conducted in a product-representative 1.5-stage HPT-TCF-LPT vane configuration under Mach-similarity in the Transonic Test Turbine Facility (TTTF) at TU Graz. The blowing ratio has been demonstrated to be the dominant parameter for purge film cooling in TCFs since HPT purge flows typically have very low momentum. Even at twice the nominal blowing ratio, no cooling film detachment was observed on the TCF hub or shroud surface. Varying the density ratio in the experimentally possible range delivered no significant differences in the results. With increasing purge blowing ratios, the film cooling effectiveness in the TCF increases as expected, but the heat transfer also intensifies due to the purge injection. The circumferentially averaged film cooling on the hub scales relatively well with an offset version of the well-known Hartnett correlation (Hartnett et al., 1961, “Velocity Distributions, Temperature Distributions, Effectiveness and Heat Transfer for Air Injected Through a Tangential Slot Into a Turbulent Boundary Layer,” ASME J. Heat Transfer, 83(3), pp. 293–305) that takes into account the ingress-induced premixing of the purge flow in the cavities.

FROM VEIN TO BRAIN: ENHANCING TRAffiCKING OF CAR T-CELLS IN DIFFUSE MIDLINE GLIOMA

Abstract AIMS H3K27M-altered diffuse midline glioma (DMG) is the deadliest childhood brain tumour, with treatment limited by anatomical location and chemoresistance; palliative radiotherapy remains the mainstay of treatment. Chimeric antigen receptor (CAR) T-cell therapy produces promising pre-clinical results in treating these tumours whilst leaving interspersed normal brain cells intact. Early clinical outcomes of GD2-CAR T-cell therapy for H3K27M-altered DMG demonstrate short-lived neurological and radiological improvement. Enhancing trafficking to and infiltration into the tumour core may enhance CAR T-cell efficacy. Here, advanced T-cell engineering modules are tested for their ability to improve CAR T-cell trafficking. METHOD A library of T-cell engineering modules was created each with a unique DNA barcode to allow identification of CAR T-cells expressing a given module. The library includes chemokine receptors (CCR) to improve tumour homing by chemotaxis towards tumour-secreted chemokines, adhesion molecules to increase extravasation across the blood-brain-barrier, and molecules to degrade upregulated tumour extracellular matrix (ECM) components to improve CAR T-cell motility through the tumour. Murine T-cells were co-transduced with a CAR and barcoded advanced T-cell engineering modules and administrated intravenously in syngeneic models of high-grade glioma (HGG)/DMG. Tumour, normal brain, bone marrow, spleen and liver tissue were collected at several time points post CAR T-cell administration to assess presence of CAR T-cells using genetic barcodes. RESULTS Co-expression of advanced T-cell engineering modules did not impair CAR T-cell function in vitro. CARs co-expressing selected CCRs were preferentially detected in tumour tissue in mice with GL261-EGFRvIII or H3.3K27Mp53LOFPDGFRAWT-engrafted tumours. Findings were further validated by flow cytometry detection of selected CCR-expressing CAR T-cells as compared to CAR T-cells without additional engineering components. Similar experiments for adhesion molecules and ECM modifiers are planned. CONCLUSION Results to date indicate that CAR T-cells co-expressing selected CCRs enhance their homing to HGG/DMG tumours, encouraging further in vivo research to assess impact on CAR T-cell efficacy.

One-pot microfluidic fabrication of micro ceramic particles

In the quest for miniaturization across technical disciplines, microscale ceramic blocks emerge as pivotal components, with performance critically dependent on precise scales and intricate shapes. Sharp-edged ceramic microparticles, applied from micromachining to microelectronics, require innovative fabrication techniques for high-throughput production while maintaining structural complexity and mechanical integrity. This study introduces a “one-pot microfluidic fabrication” system incorporating two device fabrication strategies, “groove & tongue” and sliding assembling, achieving an unprecedented array of microparticles with diverse, complex shapes and refined precision, outperforming traditional methods in production rate and quality. Optimally designed sintering profiles based on derivative thermogravimetry enhance microparticles’ shape retention and structural strength. Compression and scratch tests validate the superiority of microparticles, suggesting their practicability for diverse applications, such as precise micromachining, sophisticated microrobotics and delicate microsurgical tools. This advancement marks a shift in microscale manufacturing, offering a scalable solution to meet the demanding specifications of miniaturized technology components.

Digital RMB: Regulation of Central Bank Digital Currency (CBDC) in China

Introduction. “Digital RMB” is the digital currency of the People's Bank of China that has attracted the attention of researchers around the world. This project is not the first to be put into circulation, but it is the largest in terms of the volume of issued currency and the number of people using the CBDC as a means of payment.Materials and methods. The analysis of the practice of putting into effect, as well as the basics of regulating the CBDC of the PRC, can become a source of information that allows, when making a comparison, to develop a policy of action for the regulator in relation to the digital currencies of other countries.This article considers only the CBDC of the PRC, its features, technological and non-technological components. The main source of analysis is the Program Document or the Whitepaper of the CBDC of the PRC, which is currently the only official source of information on how the currency regulation is structured. This document is one of those establishing regulatory principles and is an example of a generally accepted method of regulating innovative financial technologies at the pilot stage.Results of the study. Based on the analysis, the article offers conclusions, current and final, about what the PRC CBDC is, what its structure is, what are the features and of the PRC CBDC.Discussion and conclusion. Areas of application of the PRC CBDC are being considered, the legal effect of its implementation.

A new empirical index to track the technological novelty of inventions: A sector-level analysis

We introduce the Knowledge Origin Re-Combination Index (KORCI) to measure the ex-ante technological novelty of inventions at the sectoral level. The index is developed through the intertemporal comparison of a sequence of networks, which represents the complex connections between the technological components listed in subsequent cohorts of patent applications. This allows us to quantify the intensity of the recombination of components and the introduction of new ones at the frontier of technological knowledge. Using patent data from three sectors – artificial intelligence, computer technology, and pharmaceuticals – we are the first to document the cyclical nature of the evolution of ex-ante technological novelty of inventions across all three sectors. These evolutionary cycles, however, are not synchronized, and therefore it is unlikely that they are driven by a common innovation engine. Further investigation into the correlation between KORCI and patent growth rates reveals other differences among the sectors in both direction and strength. We conjecture that the relation between the degree of ex-ante technological novelty and invention activities depends on the specific innovation environment of the sector – whether these are process-based or product-based. Our new tool opens opportunities for new empirical research into the evolution of innovation at the sectoral level.

Enhancing Student Engagement in Learning Management Systems through Exploration of Avatars in Virtual Classrooms: A Systematic Review

The rise of online education has highlighted the crucial need to comprehend student participation in virtual learning environments. With the evolution of online learning platforms, understanding the impact of technological components, especially interactive avatars, on student engagement has become imperative. This study aims to investigate the influence of avatars on student participation in virtual classrooms. Specifically, it seeks to understand the impact of avatars on student interactions, engagement, and involvement within online learning environments. Three primary research questions guide the inquiry: the impact of avatars on student participation, the extent of technology-mediated interaction's effect on engagement, and the nuanced ways in which avatars contribute to or hinder student involvement. The study conducts a comprehensive review of existing literature, delving into the design, integration, and influence of avatars in virtual learning environments. It critically assesses technological advancements, focusing on interactive avatars, and their implications for student engagement. The methodology involves an in-depth analysis of scholarly works, educational platforms, and user experiences to gather valuable insights. The study uncovers the multifaceted impact of avatars in virtual classrooms. Interactive avatars significantly enhance student engagement and participation, fostering interactions between students and teachers as well as among peers. The customization and interactivity of avatars create a more immersive learning experience, positively influencing student involvement. Future research endeavours could explore the integration of avatars with emerging technologies like augmented reality and artificial intelligence, enhancing the depth and scope of virtual classroom interactions. Continued research in this area is essential for refining virtual learning environments and ensuring optimal student participation in the digital educational landscape.

The effectiveness of psychological interventions on diabetes distress and glycemic level in adults with type 2 diabetes: a systematic review and meta-analysis

AimsThe treatment of diabetes distress plays an important role in diabetes care; however, no meta-analysis has been performed to synthesize the short- and long-term effects of psychological interventions tailored for diabetes distress in people with type 2 diabetes. We aim to evaluate the evidence on tailored psychological interventions for diabetes distress as the primary outcome, focusing on individuals with type 2 diabetes.MethodsTwo reviewers independently searched eight databases from their inception to September 2024. EndNote X9 was used to screen records. The Revised Cochrane risk-of-bias tool for randomized trials was used to assess the risk of bias. The GRADE system was used to assess the overall certainty of the evidence. A random effect model was used to determine the mean difference or standardized mean difference with 95% CIs. Subgroup analyses based on several intervention characteristics and sensitivity analyses were also conducted.ResultsTotally, 22,279 records were yielded, and we finally included 18 studies in our systematic review. The meta-analysis included data from 16 studies representing 1639 participants. Interventions types included mindfulness-based and cognitive behavioral therapy, among others. Duration of interventions ranged from 4 weeks to 6 months. We found that psychological interventions that measured diabetes distress significantly reduced diabetes distress in the short-term in people with type 2 diabetes (SMD= -0.56; 95% CI= -0.90, -0.22; p = 0.001). Subgroup analysis indicated that this effect could be enhanced when delivered in a group format, by psychologist, using a technology component, or including participants having elevated baseline diabetes distress. However, the short- and long-term effects on HbA1c were non-significant, with results showing (MD = 0.02; 95% CI = -0.23 to 0.26; p = 0.89) and (MD = -0.27; 95% CI = -0.64 to 0.10; p = 0.15), respectively. The long-term effect on diabetes distress was also non-significant (SMD = -0.45; 95% CI = -0.93 to 0.03; p = 0.07).ConclusionsPsychological interventions tailored for diabetes distress in people with type 2 diabetes are effective in reducing the level of diabetes distress immediately after the intervention. More trials are still needed to further enrich the evidence in this area.

Theoretical investigation of Rayleigh-type surface acoustic waves with high electromechanical coupling coefficient in c-axis-tilted ScAlN film/3C-SiC substrate structure

Surface acoustic wave (SAW) resonators are essential components of mobile communication technology. Advanced performance SAW resonators are needed to support beyond fifth-generation mobile communication technology, which aims to achieve unprecedentedly high data rates and low latency using wide frequency bands in the RF spectrum. This study theoretically investigates the propagation characteristics of a non-leaky Rayleigh-type SAW (RSAW) propagating in a c-axis-tilted ScAlN film/3C-SiC substrate structure. By appropriately selecting the c-axis tilt angle and the film thickness of the ScAlN film, a high electromechanical coupling coefficient (K2) value was obtained in the second-mode RSAW (Sezawa wave). The maximum K2 value for the Sezawa wave was 8.03%, with a phase velocity of 7456 m/s and a power flow angle of 0° under the structural conditions where the K2 value was maximized. These properties offer significant advantages for achieving wide frequency bands, high operating frequencies, and ease of design for SAW resonators. The structural conditions under which good propagation characteristics were obtained in the Sezawa waves were found to coincide with the conditions that maximize the electromechanical coupling coefficient of the quasi-longitudinal wave in the ScAlN film, and a significant increase in the shear vertical component of Sezawa wave particle displacement was observed. Additionally, ScAlN films with a 40% Sc concentration can be fabricated using sputtering and molecular beam epitaxy. Recent advancements have reported the production of high-quality 3C-SiC wafers and large 3C-SiC film/silicon wafers. Therefore, the c-axis-tilted ScAlN film/3C-SiC substrate structure shows great potential as a candidate for next-generation SAW resonators.

Disinformation, Fakes and Propaganda Identifying Methods in Online Messages Based on NLP and Machine Learning Methods

A new method of propaganda analysis is proposed to identify signs and change the dynamics of the behaviour of coordinated groups based on machine learning at the processing disinformation stages. In the course of the work, two models were implemented to recognise propaganda in textual data - at the message level and the phrase level. Within the framework of solving the problem of analysis and recognition of text data, in particular, fake news on the Internet, an important component of NLP technology (natural language processing) is the classification of words in text data. In this context, classification is the assignment or assignment of textual data to one or more predefined categories or classes. For this purpose, the task of binary text classification was solved. Both models are built based on logistic regression, and in the process of data preparation and feature extraction, such methods as vectorisation using TF-IDF vectorisation (Term Frequency – Inverse Document Frequency), the BOW model (Bag-of-Words), POS marking (Part-Of-Speech), word embedding using the Word2Vec two-layer neural network, as well as manual feature extraction methods aimed at identifying specific methods of political propaganda in texts are used. The analogues of the project under development are analysed the subject area (the propaganda used in the media and the basis of its production methods) is studied. The software implementation is carried out in Python, using the seaborn, matplotlib, genism, spacy, NLTK (Natural Language Toolkit), NumPy, pandas, scikit-learn libraries. The model's score for propaganda recognition at the phrase level was obtained: 0.74, and at the message level: 0.99. The implementation of the results will significantly reduce the time required to make the most appropriate decision on the implementation of counter-disinformation measures concerning the identified coordinated groups of disinformation generation, fake news and propaganda. Different classification algorithms for detecting fake news and non-fakes or fakes identification accuracy from Internet resources ana social mass media are used as the decision tree (for non-fakes identification accuracy 0.98 and fakes identification accuracy 0.9903), the k-nearest neighbours (0.83/0.999), the random forest (0.991/0.933), the multilayer perceptron (0.9979/0.9945), the logistic regression (0.9965/0.9988), and the Bayes classifier (0.998/0.913). The logistic regression (0.9965) the multilayer perceptron (0.9979) and the Bayesian classifier (0.998) are more optimal for non-fakes news identification. The logistic regression (0.9988), the multilayer perceptron (0.9945), and k-nearest neighbours (0.999) are more optimal for identifying fake news identification.

Data flow in clinical laboratories: could metadata and peridata bridge the gap to new AI-based applications?

In the last decades, clinical laboratories have significantly advanced their technological capabilities, through the use of interconnected systems and advanced software. Laboratory Information Systems (LIS), introduced in the 1970s, have transformed into sophisticated information technology (IT) components that integrate with various digital tools, enhancing data retrieval and exchange. However, the current capabilities of LIS are not sufficient to rapidly save the extensive data, generated during the total testing process (TTP), beyond just test results. This opinion paper discusses qualitative types of TTP data, proposing how to divide laboratory-generated information into two categories, namely metadata and peridata. Being both metadata and peridata information derived from the testing process, it is proposed that the first is useful to describe the characteristics of data, while the second is for interpretation of test results. Together with standardizing preanalytical coding, the subdivision of laboratory-generated information into metadata or peridata might enhance ML studies, also by facilitating the adherence of laboratory-derived data to the Findability, Accessibility, Interoperability, and Reusability (FAIR) principles. Finally, integrating metadata and peridata into LIS can improve data usability, support clinical utility, and advance AI model development in healthcare, emphasizing the need for standardized data management practices.

Analysis of single shaft turbojet engines structures and evaluation their safety with the use of FDM-A and FAM-C diagnostic methods

The article reviews the main stages of development of single-shaft turbojet engines. Selected construction of these engines are presented divided into three periods (before, during and after World War II) and two main jet engine schemes were discussed (with a centrifugal compressor and an axial compressor). The SO-3 jet engine installed on the TS-11 “Spark” aircraft was chosen to present the method of assessing the safety of structures. The FDM-A diagnostic methods developed in AFIT were used to experimentally verify the technical condition of the engine and FAM-C, based on the analysis of disturbances in the instantaneous rotational speed of the engine shaft. The results of tests related to the assessment of engine shaft misalignment, the assessment of the degree of wear of the engine shaft bearings and the assessment of the shaft clamping force in the bearings are presented. The summary lists the main advantages of single-shaft turbojet engines (simplicity of design for a solution with a centrifugal compressor and high thrust enabling breaking the sound barrier) and their disadvantages (complex design for a solution with an axial compressor and high failure rate of shaft bearing supports as the most loaded engine component).

0-D Dynamic Performance Simulation of Hydrogen-Fueled Turboshaft Engine

In the last few decades, the problem of pollution resulting from human activities has pushed research toward zero or net-zero carbon solutions for transportation. The main objective of this paper is to perform a preliminary performance assessment of the use of hydrogen in conventional turbine engines for aeronautical applications. A 0-D dynamic model of the Allison 250 C-18 turboshaft engine was designed and validated using conventional aviation fuel (kerosene Jet A-1). A dedicated, experimental campaign covering the whole engine operating range was conducted to obtain the thermodynamic data for the main engine components: the compressor, lateral ducts, combustion chamber, high- and low-pressure turbines, and exhaust nozzle. A theoretical chemical combustion model based on the NASA-CEA database was used to account for the energy conversion process in the combustor and to obtain quantitative feedback from the model in terms of fuel consumption. Once the engine and the turbomachinery of the engine were characterized, the work focused on designing a 0-D dynamic engine model based on the engine’s characteristics and the experimental data using the MATLAB/Simulink environment, which is capable of replicating the real engine behavior. Then, the 0-D dynamic model was validated by the acquired data and used to predict the engine’s performance with a different throttle profile (close to realistic request profiles during flight). Finally, the 0-D dynamic engine model was used to predict the performance of the engine using hydrogen as the input of the theoretical combustion model. The outputs of simulations running conventional kerosene Jet A-1 and hydrogen using different throttle profiles were compared, showing up to a 64% reduction in fuel mass flow rate and a 3% increase in thermal efficiency using hydrogen in flight-like conditions. The results confirm the potential of hydrogen as a suitable alternative fuel for small turbine engines and aircraft.

Histidine-based hybrid perovskites as promising materials for wide wavelength photodetection

Layered 2D hybrid organic-inorganic perovskites (2D-HOIPs) exhibit a distinctive array of properties, including remarkable structural flexibility, enhanced resistance to moisture, and optoelectronic characteristics valuable for practical applications. Consequently, these materials are now widely acknowledged as pivotal components in optical and optoelectronic technologies. However, a significant drawback of 2D-HOIPs is their wide band gaps that has hindered their widespread application in optoelectronic devices. In this work we address this limitation by offering a novel series of 2D mixed-halide tin-based HOIPs with general formula (L-HisH)2SnBrxI4−x (where L-His = L-histidine, x = 4, 3.37, 1.70, 0.56, 0.44, and 0) for which the band gap can reach record narrow values, which are not typical for 2D-HOIPs. These compounds can be easily obtained in wide compositional range by implementing halide substitution approach. Each hybrid perovskite features a chiral structure imparted by chiral L-histidinium(+) cations interleaved between corner-shared tin halide octahedra, organized into single-layer thin inorganic slabs. Crucially, these new materials provide a high degree of flexibility in tuning their band gaps throughout the entire visible light spectrum, encompassing a range between 1.82 and 3.05 eV. As a “proof-of-concept”, we created a prototype HOIPs photodetector in which this HOIP was used as an active layer. It is noteworthy that the band gap of pure iodide perovskite is surprisingly narrow for this class of materials. The production of semiconductor materials with a variable width of the optical bandgap is the key to more versatile and diverse applications of these materials in the active components of modern optoelectronic devices. For the obtained prototype, light detection is observed in the wide range covering UV, visible and near-IR regions, marking a record achievement for 2D-HOIPs. Beyond photodetectors, these new histidine-based perovskites hold promise for applications in various other optoelectronic devices, including solar cells, photodiodes, phototransistors, polarized light detectors, and more.

Crystal plasticity based investigation of the effects of additive manufactured voids on the strain localisation behaviour of Ti-6Al-4V

The presence of defects produced by additive manufactured (AM) processes in structural Ti alloys such as Ti-6Al-4V is known to have serious implications on the deformation and fatigue behaviour of engineering components. However, there is little understanding about the localised plastic deformation patterns that develop around AM defects, and the associated local conditions that could lead to the nucleation of micro-cracks under creep loading conditions. In this work, the effects of the morphology and volume fraction of AM defects and temperature on the strain localisation behaviour around such defects in Ti-6Al-4V will be addressed. To that purpose, a novel rate-dependent crystal plasticity formulation is proposed to describe the mechanical behaviour of the alloy’s predominant α′(HCP)-phase. Representative volume elements (RVEs) of the AM produced microstructures are digitally reconstructed from EBSD orientation maps obtained on planes perpendicular and transversal to the microstructure’s AM growth direction. Calibration of the single crystal model for the α′-phase is carried out from macroscopic uniaxial tensile data from polycrystalline AM specimens at different strain rates and temperatures and published creep data.Furthermore, RVEs containing AM defects of different morphologies and volume fractions are relied upon to investigate the strain localisation behaviour around the defects under uniaxial loading at ambient and high temperatures. It is found that the extent of the localised accumulated plastic strain around defects depends greatly on whether the voids surface are smooth or have sharp corners, with the latter being associated with more severe localisation patterns. Moreover, a numerical investigation into the crack initiation behaviour of AM Ti-6Al-4V under uniaxial creep loading at 450 ° C revealed that the development of the local conditions suitable for the nucleation of creep damage/micro-cracks is accelerated in the presence of typical AM defects, and the extent of that acceleration depends strongly on their morphology. An AM defect shape parameter is introduced to quantify the way their morphology affects the time for creep crack initiation/damage.

Analisis Pemeliharaan Menggunakan Metode Reliability pada Sistem Gas Turbine Engine untuk Mengetahui Kinerja Engine Turbofan CFM56-3 pada Pesawat Boeing 737-500

In carrying out structured maintenance, a method is needed to increase the durability of an aircraft component, one of the methods used is the reliability method. The reliability of aircraft components is very necessary to ensure that each aircraft component is serviceable and runs according to its function in the aircraft system, so to increase the reliability of an aircraft component, the reliability method is very important to do. This study aims to determine the critical life time limit of the asset or system or equipment function and identify the failure mode that occurs in the Gas Turbine Engine component of the Boeing 737-500 aircraft because if this engine fails, it can result in flight delays and if not handled immediately can cause the aircraft to experience Aircraft on Ground (AOG) conditions, because it has the potential to disrupt airworthiness and threaten safety. This study uses exploratory research which aims to simplify problems to make them easier to solve. This study uses the Pareto diagram method to determine the highest type of failure in components, then analyzes it using the failure mode effect analysis (FMEA) method. Based on FMECA and FTA analysis, there are 3 failure modes, the failure modes include mechanical system (Bleed Valve), pneumatic system (Butterfly Shaft), electrical system (actuator). The failure was due to the occurrence of the top event part consumable, namely the bleed valve part with an RPN value of 192, followed by the butterfly shaft part with an RPN value of 75 and the Actuator part with an RPN value of 72. The pneumatic system and electrical system categories are prioritized to carry out preventive maintenance, which means it is a solution from industry players in an effort to maximize maintenance of the turbofan engine system accompanied by technical or economic analysis to ensure a system in extending the service life of parts in the aircraft system.

Influence of randomly placed resonant aggregates on the attenuation properties of metaconcrete: A numerical study

Concrete is a key material for many structural components in engineering, but its acoustic performance remains under discussion. Hence, the potential of the so-called metaconcrete has gained attention in research, mainly due to its capability to control vibrations and sound transmission when resonant aggregates are embedded in the concrete. These resonant aggregates are designed to have resonant frequencies regarding frequency bands of interest, so the interaction with the incident sound waves is attenuated within those frequencies. While available research has focused on the characterization of metaconcrete with a periodic arrangement of resonant aggregates, there is a gap regarding how their random allocation affects the characterization of metaconcrete. This study focuses on the numerical analysis of metaconcrete and the influence of randomly placed resonant aggregates on its attenuation properties. The numerical approach concentrates on the aggregate's material composition, location and volume fraction within the concrete to identify configurations that exhibit great wave attenuation. The results have shown that the attenuation effect is substantially advantageous when using a multi-frequency configuration for aggregates within the metaconcrete. Additionally, the random embedding of resonant aggregates offers a practical solution for their application in concrete structures.