Assembly Configurations Research Articles

Design and optimization of a source (reflector/shielding) performance test system based on (241Am-Be)-paraffin thermal neutron irradiation device

Laboratory measurements and Monte Carlo simulations were conducted to investigate the feasibility of employing a (reflector/shield) to improve the efficiency of a thermal neutron irradiator utilizing a paraffin-moderated single 241Am-Be source with an activity of 1 Ci. A multi-parameter optimization was performed to evaluate the potential of natural lead (Pb) and 90 % enriched 208Pb lead (208Pb(90 %)) in terms of increasing the neutron production while minimizing the total dose equivalent rate. The laboratory-derived optimal configuration for the (reflector/shield) assembly demonstrated that Pb significantly increased the neutron flux by approximately 58 % and reduced the total dose equivalent rate to 0.00443 mSv/h, thereby allowing for a workload of 4500 h within the annual permissible dose limit of 20 mSv. The MCNP simulations validated the potentials of Pb and confirmed the superiority of 208Pb(90 %) in terms of increasing neutron flux to about 26 % compared to that measured for Pb, while also minimizing the total dose equivalent rate to 0.0037 mSv/h. Thus, enabling a workload of approximately 5400 h, which is higher by about 20 % compared to that permitted by Pb based on measurements. The geometrical configuration and results promoted the use of the proposed TNI device primarily for prompt gamma neutron activation analysis (PGNAA).

Identifying electrochemical processes by distribution of relaxation times in proton exchange membrane electrolyzers

Distribution of relaxation time (DRT) is used to interpret electrochemical impedance spectroscopy (EIS) for proton exchange membrane (PEM) water electrolyzers, with an attempt to separate overlapped relaxation processes in Nyquist plots. By varying operating conditions and catalyst loadings, four main relaxation peaks arising from EIS can be identified and successfully separated from low to high frequencies as (P1) mass transport, (P2) oxygen evolution reaction kinetics, (P3) reaction kinetics (with faster time constant than P2), and (P4) ionic transport. The shape, height, and frequency of the DRT peaks change with different membrane electrode assembly (MEA) configurations. Electron microscopy reveals distinct features from the cross-sectioned MEAs which verify critical DRT results in that increasing the iridium (Ir)-anode loading from 0.2 mgIr/cm2 to 1.5 mgIr/cm2 reduces kinetic losses due to higher site-access; a thick and compacted anode, however, also triggers higher ohmic resistances from membrane/catalyst layer hydration and increases transport losses due to longer ionomer pathways. DRT provides higher resolution to EIS for deconvoluting processes with different relaxation times and the quantification of DRT peaks improves the accounting of total losses from each process.

Tuning architectural organization of eukaryotic P450 system to boost bioproduction in Escherichia coli

Eukaryotic cytochrome P450 enzymes, generally colocalizing with their redox partner cytochrome P450 reductase (CPR) on the cytoplasmic surface of organelle membranes, often perform poorly in prokaryotic cells, whether expressed with CPR as a tandem chimera or free-floating individuals, causing a low titer of heterologous chemicals. To improve their biosynthetic performance in Escherichia coli, here, we architecturally design self-assembled alternatives of eukaryotic P450 system using reconstructed P450 and CPR, and create a set of N-termini-bridged P450-CPR heterodimers as the counterparts of eukaryotic P450 system with N-terminus-guided colocalization. The covalent counterparts show superior and robust biosynthetic performance, and the N-termini-bridged architecture is validated to improve the biosynthetic performance of both plant and human P450 systems. Furthermore, the architectural configuration of protein assemblies has an inherent effect on the biosynthetic performance of N-termini-bridged P450-CPR heterodimers. The results suggest that spatial architecture-guided protein assembly could serve as an efficient strategy for improving the biosynthetic performance of protein complexes, particularly those related to eukaryotic membranes, in prokaryotic and even eukaryotic hosts.

Movement Recognition and Injury Risk Assessment of Wushu Athletes Based on Computer Vision

This paper aims to study a method of movement recognition and injury risk assessment for Wushu athletes based on computer vision. Studying the optimization of Wushu athletes’ movement trajectory can effectively improve the athletes’ movement quality. Based on a hybrid real-time synchronization algorithm, the arm motion trajectory model of martial arts athletes is studied. A dynamic and static arm recognition algorithm is proposed, and the motion feature extraction method in Wushu movement is studied. Dynamic arm recognition typically relies on the collection of video or image sequences. These sequences contain the position, shape, and motion trajectory of the arm at different time points. Static arm recognition mainly relies on the acquisition of a single image or image frame. The dynamic arm recognition algorithm captures the motion trajectory and changes of the arm by processing video or image sequences, while the static arm recognition algorithm only processes individual images or image frames. On this basis, the design of the computer software architecture of the digital site system is completed. The real-time collection, analysis, display and storage of motion information and assembly configuration are realized. The simulation results show that the method has high accuracy and provides a powerful scientific basis for improving athletes’ movement injuries. To predict the risk of injury an athlete may suffer during training or competition.

Assessing the performance of three experimental methods to investigate air path inside wall assemblies

Air leakages in buildings’ envelopes can lead to an over-consumption of energy and to additional issues such as moisture damage and poor indoor environment. The leakage air flow rate is usually assessed at the building scale using a pressurization test and leakage locations are commonly detected by infrared thermography or smoke. However, little is known about the air paths within wall assemblies, despite the need for detailed experimental data to validate numerical models for the coupled heat, moisture and pollutants transfers. One of the reasons is the difficulty to find adapted and robust experimental methods.In this paper, three experimental laboratory approaches are tested on simple light-wall assembly configurations: the implementation of three-dimensional grids of thermocouples and relative humidity sensors within the wall, and the use of a micro-particle tracer. The results are compared with each other as well as with numerical simulations.It was found that thermocouple grid has limited intrusiveness, good accuracy and response time but results are subject to flow fluctuations. Moreover, heat capacity and conductive transfer within materials complicate the correlation between heat and air transfers. Humidity sensors grid avoids the latter issue but is intrusive, overestimating air dispersion. The micro-particle tracer has the advantage of being non-intrusive and less impacted by flow fluctuations but its ability to track the air flow is strongly linked with the insulation filtration properties and the flow velocity. Overall this method seems to provide the best results but it is also the most complex and time-consuming one.

Reference-Electrode Configuration in CO2 Electrolysis (CO2E) and Anion-Exchange Membrane Water Electrolysis (AEMWE) Cells for Degradation and Stability Evaluation

CO2 electrolysis (CO2E) and anion-exchange membrane water electrolysis (AEMWE) have both been identified as promising technologies for reducing emissions from the industrial and energy sectors in pursuit of achieving net-zero goals.1,2,3,4 Recent developments of electrocatalysts, membranes, and electrolyser cell design have resulted in rapid progress of CO2E and AEMWE, achieving high current densities and faradaic efficiencies at the laboratory scale.1,2 However, the long-term stability of these technologies requires improvement if they are to be deployed at commercially relevant scales.2,5 Unfortunately, degradation phenomena such as; cathode flooding6, 10, catalyst degradation7, membrane instability8,9, and salt precipitation10 are difficult to diagnose electrochemically, without the ability to decouple resistance contributions in-situ.We have therefore developed a 3-electrode technique and explored protocols that allow for the decoupling of cathode and anode overpotentials during long-term stability measurements.By using an edge-type reference electrode connected to the membrane through a liquid electrolyte bridge, we successfully demonstrate the ability to assess the performance of individual components within different membrane-electrode assembly (MEA) configurations. We highlight instabilities with using edge-type reference electrodes such as changes in the pH of the electrolyte bridge, and discuss efforts to mitigate these issues to permit long-term stability testing. We then demonstrate how this method can be used to provide more insights into degradation phenomena in both CO2 and AEM water electrolyser cells, showing early diagnosis - up to 7 hours before detection from a conventional 2-electrode set-up - of failure mechanisms during stability testing.The proposed 3-electrode technique is capable of separating anode and cathode overpotentials over the course of extended testing periods and provides a platform to study the electrochemical response of individual electrolyser components to various degradation phenomena, and the durability of CO2E and AEMWE materials. Critical gaps in knowledge surrounding these issues can be better understood, which will enable these technologies to advance to the next stages of development.

Analyzing (Th-233U-235U)O2 fuel performance in various assembly configurations: A comparative neutronic study

Analyzing (Th-233U-235U)O2 fuel performance in various assembly configurations: A comparative neutronic study

Assessing the performance of infrared thermography and PIV methods to identify and characterize the air inlets and outlets in wall assemblies

Building airtightness is crucial for reducing energy demand in the building sector and preventing moisture damage and indoor environment quality issues. Mandatory airtightness tests are now commonly performed in many countries to quantify the total envelope leakage rate of real buildings. For a more precise diagnosis, air leakages are usually identified by infrared thermography or visualized by smoke. However, a finer analysis is also needed to characterize precisely the air flow through specific leaks. Numerical models have been developed for this purpose but experimental data are necessary to validate them. In this paper, two experimental approaches are tested on simple light-wall assembly configurations to address this need: infrared thermography (IRT) and the innovative use of particle image velocimetry (PIV) with a specific experimental set-up and protocol developed. The results are compared with each other as well as with numerical simulations. Results showed that both techniques can be applied for the experimental characterization of the air inlet/outlet of a wall assembly with different advantages and drawbacks. IRT is easy to implement, non-intrusive, possible for in-situ investigations, but the correlation between the thermographs and the air dispersion at the outlet is not straight forward due to thermal inertia and heat conduction issues. PIV gives direct results on the velocity field and enables quantitative analysis of air flow rates for various configurations, with some limitations: a difficult implementation; restrictions on the possible infiltration velocity range and difficulties to visualize the flow exactly at the interface with the wall assembly.

Multi‐Array Tubular Microbial Fuel Cell‐Based Biosensor with Membrane Electrode Assembled Air‐Cathodes

ABSTRACTUsing microbial fuel cells (MFCs) as biosensors ensures a sustainable method for water quality detection. However, the research on MFC‐based biosensors with a tubular setup is still scarce. In this study, a tubular multi‐array MFC‐based biosensor setup with air‐cathodes was assembled under the membrane electrode assembly configuration. Three different materials, including carbon black (CB), Pt/C (PtC), and polyaniline (PANI), were synthesized and coated on the membrane‐facing side of the air‐cathode to demonstrate the effects of modified air‐cathodes on the overall performance of the MFC‐biosensors. Unmodified carbon cloths were used as anodes. Three days of startup period were required by the biosensors before producing an electrical signal output. The highest current density was obtained by the polytetrafluoroethylene (PTFE)/CB/PtC (0.31 A m−2) sample followed by PTFE/CB/PANI (0.09 A m−2), and lastly PTFE/CB (0.05 A m−2). The control (PTFE only) sample did not generate any noticeable electrical signal. The electrochemical impedance spectroscopy analysis showed that the incorporation of PtC on the PTFE/CB sample lowered the charge transfer resistance (Rct), whereas the addition of PANI increased the Rct. Despite the differences in Rct values, both PTFE/CB/PtC and PTFE/CB/PANI samples demonstrated a better current density production than the PTFE/CB sample. Thus, modified air‐cathodes further elevated the biosensor's performance.

Nacelle modeling considerations for wind turbines using large-eddy simulations

Two setups are used to investigate differences between modeling a wind turbine nacelle by means of an actuator-line model (ALM) and a wall-model (WM) using large-eddy simulations. One advantage of the ALM is that it requires a lower mesh refinement, making it less computationally costly. In the first setup, the nacelle is in standalone configuration and the ALM results show a much lower turbulence intensity and a significantly slower wake recovery when compared to the WM cases. In the second setup, the nacelle is in a rotor-nacelle assembly configuration and many variations of the ALM are tested in order to match the results from the experiment addressed in the OC6 task phase III. Contrary to previous findings that the nacelle might affect the turbine loads, this study shows that the improved match with the experiment stems from the increased mesh refinement in the nacelle region rather than the actual presence of the nacelle. Nevertheless, the wake profiles in the near-wake show a very good agreement between the ALM and WM, regardless of the refinement in the nacelle region. These cases also show a higher wake deficit than not using any nacelle at all.

Neutronic assessment and optimization of ACP-100 reactor core models to achieve unit multiplication and radial power peaking factor

This study focuses on the neutronic and burnup assessment of the PWR-based Chinese ACP-100 SMR core. Four different core models with varying fuel compositions and assembly configurations were analyzed using the Monte Carlo code SERPENT 2. Three of these models shared uniformly enriched fuel assemblies of 3 wt.%, 4 wt.%, and 4.45 wt.% 235U respectively, while the fourth model (the proposed design for the ACP-100 in this study) featured a mix of differently enriched fuel assemblies along with the inclusion of burnable absorbers. The burnup analysis of the cores spanned 1570 EFPDs, evaluating several neutronic parameters (beta effective, reactivity coefficients) as well as fuel cycle characteristics (cycle burnup, discharge burnup and cycle length). Changes in the isotopic concentration of fissile, fertile, and poison materials were observed and the assembly-wise linear power distribution, neutron flux spectra, and radial power peaking factors of the models were determined. In the mixed core, a combination of borated water, IFBAs and control rods were employed to achieve exact criticality (unit keff) and uniform power distribution (unit radial power peaking factor). Insertion of control rods into 41 of the 57 assemblies, in conjunction with IFBAs placed strategically, attained a near unit radial power peaking factor (PPF) of 1.0586. Finally, the combination of IFBAs, sol-bor of 936 ppm concentration, and CRs with rod worth of 414.33 pcm per assembly brought down the keff to 1.000, but increased the PPF to 1.117. While the achievement of uniform power distribution came at the cost of fuel burnup, the proposed mixed core successfully remained critical for over 1.5 years and reached a discharge burnup of 23.37 GWd/t for a two-batch refueling scheme.

Cu-optimized long-range interaction between Co nanoparticles and Co single atoms: Improved Fenton-like reaction activity

The interplay between multi-atom assembly configurations and single atoms (SAs) has been gaining attention in research. However, the effect of long-term range interactions between SAs and multi-atom assemblies on the orbital filling characteristics has yet to be investigated. In this context, we introduced copper (Cu) doping to strengthen the interaction between cobalt (Co) nanoparticles (NPs) and Co SAs by promoting the spontaneous formation of Co–Cu alloy NPs that tends toward aggregation owing to its negative cohesive energy (−0.06454), instead of forming Cu SAs. The incorporation of Cu within the Co–Cu alloy NPs, compared to the pure Co NPs, significantly expedites the kinetics of peroxymonosulfate (PMS) oxidation processes on Co SAs. Unlike Co NPs, Co–Cu NPs facilitate electron rearrangement in the d orbitals (especially dz2 and dxz) near the Fermi level in Co SAs, thereby optimizing the dz2–O (PMS) and dxz–O (SO5−) orbital interaction. Eventually, the Co–Cu alloy NPs embedded in nitrogen-doped carbon (CC@CNC) catalysts rapidly eliminated 80.67% of 20 mg L−1 carbamazepine (CBZ) within 5 min. This performance significantly surpasses that of catalysts consisting solely of Co NPs in a similar matrix (C@CNC), which achieved a 58.99% reduction in 5 min. The quasi in situ characterization suggested that PMS acts as an electron donor and will transfer electrons to Co SAs, generating 1O2 for contaminant abatement. This study offers valuable insights into the mechanisms by which composite active sites formed through multi-atom assembly interact at the atomic orbital level to achieve high-efficiency PMS-based advanced oxidation processes at the atomic orbital level.

Failure Analysis of Large-Size Drilling Tools in the Oil and Gas Industry

Abstract The safety problem of large-size drilling tools in large-size boreholes has become increasingly prominent with the exploration and development of deep and ultradeep wells. This study analyzes the causes of large-size drilling tool failures from the engineering point of view via statistical analysis, experimental material test, and vibration and bending analyses. Results show that the violent downhole vibration changes the drilling tool's mechanical properties. These changes result in an uneven distribution of hardness and reduced impact work, finally leading to the initiation of fatigue cracks at stress concentration points. Drilling tool bending is closely related to drilling parameters and bottom hole assembly (BHA) configuration. Unreasonable BHA configuration and drilling parameters increase BHA bending and accelerate fatigue failure. Once a crack is generated, the corrosive ions in water-based drilling fluids invade the microcrack, causing the corrosion of the drilling tool material. As a result, the strength is reduced, and the fracture is aggravated. Therefore, measures for preventing the failure of large-size drilling tools are proposed. We hope that the results of this work can provide useful guidance for drilling engineers.

Understanding the extent of detectability and heat transfer characteristics of hidden defects on metal-based envelopes

Metal hidden defects can either be due to corrosion or voids. The extent of their detectability and heat transfer characteristics, particularly with light-colored surface paints and assembly configurations, have been less explored. Observing surface thermal contrast and rate of temperature change (RTC) during “long-pulse” excitation can detect hidden defects regardless of the metal type, paint color, and assembly configuration. However, results from the active thermography approach only indicate their presence and not their location and type. Corroded layers have a lower surface temperature and RTC due to faster heat transfer, while pitted layers have a higher surface temperature and RTC.

Elucidating Structural Configuration of Lipid Assemblies for mRNA Delivery Systems.

The development of mRNA delivery systems utilizing lipid-based assemblies holds immense potential for precise control of gene expression and targeted therapeutic interventions. Despite advancements in lipid-based gene delivery systems, a critical knowledge gap remains in understanding how the biophysical characteristics of lipid assemblies and mRNA complexes influence these systems. Herein, we investigate the biophysical properties of cationic liposomes and their role in shaping mRNA lipoplexes by comparing various fabrication methods. Notably, an innovative fabrication technique called the liposome under cryo-assembly (LUCA) cycle, involving a precisely controlled freeze-thaw-vortex process, produces distinctive onion-like concentric multilamellar structures in cationic DOTAP/DOPE liposomes, in contrast to a conventional extrusion method that yields unilamellar liposomes. The inclusion of short-chain DHPC lipids further modulates the structure of cationic liposomes, transforming them from multilamellar to unilamellar structures during the LUCA cycle. Furthermore, the biophysical and biological evaluations of mRNA lipoplexes unveil that the optimal N/P charge ratio in the lipoplex can vary depending on the structure of initial cationic liposomes. Cryo-EM structural analysis demonstrates that multilamellar cationic liposomes induce two distinct interlamellar spacings in cationic lipoplexes, emphasizing the significant impact of the liposome structures on the final structure of mRNA lipoplexes. Taken together, our results provide an intriguing insight into the relationship between lipid assembly structures and the biophysical characteristics of the resulting lipoplexes. These relationships may open the door for advancing lipid-based mRNA delivery systems through more streamlined manufacturing processes.

DeepCraft: imitation learning method in a cointelligent design to production process to deliver architectural scenarios

The recent advancements in digital technologies and artificial intelligence in the architecture, engineering, construction, and operation sector (AECO) have induced high demands on the digital skills of human experts, builders, and workers. At the same time, to satisfy the standards of the production-efficient AECO sector by reducing costs, energy, health risk, material resources, and labor demand through efficient production and construction methods such as design for manufacture and assembly (DfMA), it is necessary to resolve efficiency-related problems in mutual human‒machine collaborations. In this article, a method utilizing artificial intelligence (AI), namely, generative adversarial imitation learning (GAIL), is presented then evaluated in two independent experiments related to the processes of DfMA as an efficient human‒machine collaboration. These experiments include a) training the digital twin of a robot to execute a robotic toolpath according to human gestures and b) the generation of a spatial configuration driven by a human's design intent provided in a demonstration. The framework encompasses human intelligence and creativity, which the AI agent in the learning process observes, understands, learns, and imitates. For both experimental cases, the human demonstration, the agent's training, the toolpath execution, and the assembly configuration process are conducted digitally. Following the scenario generated by an AI agent in a digital space, physical assembly is undertaken by human builders as the next step. The implemented workflow successfully delivers the learned toolpath and scalable spatial assemblies, articulating human intelligence, intuition, and creativity in the cocreative design.

Modeling and simulating axial vibrations on the crarkshaft of the large two-stroke marine diesel engine

The axial vibration is the strong vibrated phenomenon occurring on the main propulsion using a large two-stroke marine diesel engine. This article researches to build a mathematical model of the axial stiffness coefficient and force generated by the geometric configuration of the crank pin-crank web assemblies and the combustion gas force. The numerical simulation is performed by finite element method, using ANSYS software, applied to the main engine MAN B&W 6G70ME. Keywords: Axial stiffness; crank pin–crank web set; axial force; diesel crankshaft; large two-stroke marine diesel engine; Axial vibration simulation.

Reactor core design with practical gadolinia burnable absorbers for soluble boron-free operation in the innovative SMR

The development of soluble boron-free (SBF) operation in the innovative Small Modular Reactor (i-SMR) requires effective strategies for managing excess reactivity over extended operational cycles. This paper introduces a practical approach to reactor core design for SBF operation in i-SMR, emphasizing the use of gadolinia burnable absorbers (BA). The study investigates the feasibility of Highly Intensive and Discrete Gadolinia/Alumina Burnable Absorber (HIGA) rods for controlling excess reactivity sustainably. Through comprehensive analysis and simulations, the reactivity behavior with varying quantities of HIGA rods is examined, leading to the development of optimized fuel assembly designs. Furthermore, the integration of HIGA rods with integral gadolinia BA rods is discussed to enhance reactivity control and operational flexibility further. This approach utilizes the spatial self-shielding effect of gadolinia for extended reactivity management, crucial for stable and efficient reactor performance. The paper thoroughly addresses core design considerations, including fuel assembly configurations and control rod patterns, to ensure safety and performance in initial and reload cycles. This research advances the development of SBF operation in i-SMR by offering practical reactivity management solutions.

A Perspective of Bioinspired Interfaces Applied in Renewable Energy Storage and Conversion Devices.

The natural world renders a large number of opportunities to design intriguing structures and fascinating functions for innovations of advanced surfaces and interfaces. Currently, bioinspired interfaces have attracted much attention in practical applications of renewable energy storage and conversion devices including rechargeable batteries, fuel cells, dye-sensitized solar cells, and supercapacitors. By mimicking miscellaneous natural creatures, many novel bioinspired interfaces with various components, structures, morphology, and configurations are exerted on the devices' electrodes, electrolytes, additives, separators, and catalyst matrixes, resorting to their wonderful mechanical, optical, electrical, physical, chemical, and electrochemical features compared with the corresponding traditional modes. In this Perspective, the principles of designing bioinspired interfaces are discussed with respect to biomimetic chemical components, physical morphologies, biochemical reactions, and macrobiomimetic assembly configurations. A brief summary, subsequently, is mainly focused on the recent progress on bioinspired interfaces applied in key materials for rechargeable batteries. Ultimately, a critical comment is projected on significant opportunities and challenges existing in the future development course of bioinspired interfaces. It is expected that this Perspective is able to provide a profound perception into some underlying artificial intelligent energy storage and conversion device design as a promising candidate to resolve the global energy crisis and environmental pollution.

Investigation and Analysis of Influential Parameters in Bottomhole Stick–Slip Calculation during Vertical Drilling Operations

The critical factors that affect bottomhole stick–slip vibrations during vertical drilling operations are thoroughly investigated and analyzed in this research. Influential factors, such as rotation speed, weight on bit (WOB), bottom hole assembly (BHA) configuration, and formation properties, were studied in order to understand their part in the stick–slip phenomena. The analysis is based on a thorough review of previous research conducted on stick–slip drilling vibrations. A mathematical model was created that not only explains axial vibrations but also includes the torsional vibrations present in stick–slip occurrences, which helps with understanding the stick–slip phenomena better. This model can be used as an analytical tool to predict and evaluate the behavior of drilling systems under various operational circumstances. Furthermore, two drilling tests using a WellScan simulator were performed to validate the research findings and assess mitigation techniques’ viability. These test scenarios reflect the stick–slip vibration-producing situations, allowing us to test mitigation strategies. The finding of this study shows the effectiveness of two tactics for reducing stick–slip vibrations. First was the reduction of WOB, which successfully lowered the occurrence of stick–slip vibrations. The second was the increase in the rotation speed, which helped to control the stick–slip problem and increased the drilling speed. This study explains the complex dynamics of stick–slip vibrations during vertical drilling and offers practical, tried-and-true methods for reducing their adverse effects on drilling operations.