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Abstract Aiming to efficiently simulate the transient process of transpiration cooling with phase change and reveal the convection mechanism between fluid and porous media particles in a continuum scale, a new two-phase mixture model is developed by incorporating the local thermal non-equilibrium effect. Considering the low-pressure and high overload working conditions of hypersonic flying, the heat and mass transfer induced by capillary and inertial body forces are analyzed for sub-cooled, saturated and super-heated states of water coolant under varying saturation pressures. After the validation of the model, transient simulations for different external factors, including spatially-varied heat flux, coolant mass flux, time-dependent external pressure and aircraft acceleration are conducted. The results show that the vapor blockage patterns at the outlet are highly dependent on the injection mass flux value and the external pressure, and the reduced saturation temperature at low external pressure leads to early boiling off and vapor blockage. The motion of flying has a large influence on the cooling effect, as the inertial force could change the flow pattern of the fluid inside significantly. The comparison of the results from 2-D and 3-D simulations suggests that 3-D simulation shall be conducted for practical application of transpiration cooling, as the thermal protection efficiency may be overestimated by the 2-D results due to the assumption of an infinite width length of the porous plate.

Hot air anti-icing systems are essential in aviation engines, preventing ice formation on inlet components during high-altitude flights. A critical factor in enhancing these systems' effectiveness is the application of jet impingement technology. In order to further enhance the performance of jet impingement heat transfer in this application scenario, the research assesses the impact of nozzle type and surface protrusion type on the anti-icing system's performance by integrating experimental and numerical approaches. Findings reveal that circular nozzles outperform swirl and satellite nozzles in heat transfer efficiency in the application of aviation anti-icing system with high jet Reynolds number. The average Nusselt number, indicative of heat transfer rate, can be increased by up to 10.54 % with protrusions. For surface protrusions, sequentially-arranged cylinder protrusions are more effective at Reynolds numbers between 8000 and 48000. Cross-arranged circular truncated cone protrusions do better at higher Reynolds numbers, from 48000 to 80000 which is the range relevant to the hot air anti-icing system. Comparing concave and flat plates with the same type of protrusions, the former shows superior heat transfer performance. The study also establishes correlations for convective heat transfer coefficients and attenuation coefficients on the concave plate with sequentially-arranged cylinder protrusions. By applying the cross-arranged circular truncated cone protrusions, which proved to be the best in our experiments, to the engine nacelle's anti-icing section, the numerical results indicate a 6.21 % increase in anti-icing thermal efficiency and an 8.31 % decrease in air bleed capacity, all under the same heat transfer conditions. The use of protrusion structures in the anti-icing system of an engine nacelle boosts thermal efficiency, lowers air bleed capacity, and reduces the fuel penalty, thereby optimizing overall performance.

BackgroundIntrahepatic cholangiocarcinoma (iCCA) is a highly aggressive cancer with a dismal prognosis and few effective therapeutic approaches. This study aimed to investigate the efficacy, safety, and predictive biomarkers of hepatic arterial infusion chemotherapy (FOLFOX-HAIC) in combination with lenvatinib and PD-1 inhibitor for patients with advanced iCCA.MethodsLocally advanced or metastatic iCCA patients receiving the triple combination therapy of lenvatinib, PD-1 inhibitor, and FOLFOX-HAIC were included in this retrospective study. Primary endpoint was the progression-free survival, evaluated using the RECIST criterion. The secondary endpoints included overall survival, objective response rate, and safety. Whole exome and RNA sequencing of tumor biopsy tissues were performed for biomarker exploration.ResultsBetween May, 2019 and December 2022, a total of 46 patients were included in this study. The primary endpoint showed a median progression-free survival of 9.40 months (95% CI: 5.28-13.52), with a 6-month progression-free survival rate of 76.1%. The median overall survival was 16.77 months (95% CI, 14.20-19.33), with an objective response rate of 47.8% and disease control rate of 91.3% per RECIST. In addition, 4.3% and 8.7% of patients achieved complete response of all lesions and intrahepatic target lesions per mRECIST, respectively. The most common treatment-related adverse events were neutropenia, thrombocytopenia, elevated aspartate aminotransferase and alanine aminotransferase level. Furthermore, integrated analysis of genetic, transcriptomic, and immunohistochemistry data revealed that pre-existing immunity (high expression level of immune-related signatures and intra-tumoral CD8+ T cell density) in baseline tumor tissues was associated with superior clinical benefits. However, the evaluation of tumor mutation burden did not show potential predictive value in this triple combination.ConclusionFOLFOX-HAIC in combination with lenvatinib and PD-1 inhibitor demonstrated a promising antitumor activity with manageable safety profiles in patients with advanced iCCA. Moreover, our study also revealed new perspectives on potential biomarkers for clinical efficacy.

Background & Aims: The mechanism underlying resistance to immunotherapy involves engagement of immune checkpoint pathways. The transcriptional and epigenetic processes of checkpoint molecules, however, have not been well investigated. We thus studied whether the transcription factor myeloid zinc finger 1 (MZF1) may promote resistance to immunotherapy in hepatocellular carcinoma (HCC). Methods: Single-cell RNA-sequencing was performed to study the correlation between MZF1 and tumour microenvironment features in six patients with HCC. Combined immunohistochemistry and multi-immunofluorescence analyses were performed for verification. Ectopic expression of MZF1 was used in both orthotopic and genetically engineered hydrodynamic mouse HCC models for in vivo experiments. Proteome analysis, including protein degradation assays, ubiquitination assays, and co-immunoprecipitation assays, revealed the function of MZF1 in immune checkpoint pathways. Results: Single-cell RNA-sequencing suggested an immunosuppressive environment and a strong correlation with the immune checkpoint programmed death ligand 1 (PD-L1) in MZF1-overexpressing tumours. Analyses of 163 HCC samples demonstrated that MZF1 expression in HCC cells is associated with decreased T-cell infiltration. In vivo experiments showed that ectopic MZF1 expression in HCC cells impairs T-cell recruitment, resulting in resistance to immune checkpoint blockade. Mechanistically, MZF1 accelerated PD-L1 ubiquitination by binding to the cyclin-dependent kinase 4 (CDK4) activation site, while a direct bond between CDK4 and MZF1 led to increased MZF1 expression. Conclusions: MZF1 promotes PD-L1 ubiquitination via CDK4 and possibly MZF1. Inhibition of CDK4 can therefore restore PD-L1 expression and may be a potential strategy for combination with anti-PD-L1 antibodies. Impact and implications: Resistance to immune checkpoint blockade with anti-programmed death ligand 1 (PD-L1) antibody therapy is attributed to oncogenic alterations of tumour cells, however, effective countermeasures are yet to be established. Here, we report that the transcription factor myeloid zinc finger 1 (MZF1) can bind to the cyclin-dependent kinase 4 (CDK4) activation site and accelerate PD-L1 ubiquitination. A CDK4 inhibitor therefore enhances anti-PD-L1 antibody efficacy by blocking MZF1 signalling. This indicates a potential benefit of combining CDK4 inhibitors and anti-PD-L1 antibodies for the treatment of advanced HCC.

Regenerative cooling by endothermic hydrocarbon fuel (EHF) is one of the most promising techniques for thermal management of supersonic or hypersonic aircraft. How to maintain the fuel working in proper states is an important issue to maximize the cooling potential of EHT. This work proposes a novel working state map, including risking zone (RZ), thermal cracking zone (TCZ), supercritical zone (SupZ) and subcritical zone (SubZ), to differentiate possible working states of an EHF during regenerative cooling. Using n-decane flowing in a circular tube as an example, the boundaries of four zones are determined by numerical simulation covering different heat fluxes (0.2–4.0 MW·m−2) and mass flow rates (0.5–10.5 g·s−1) under two operating pressures (3.45 and 5.00 MPa). Empirical correlations for three boundary lines are obtained and the maximum cooling capacity is identified, as well as the identification of the pressure effect. The revelation of such new perspective of regenerative cooling is of great implication to the design and optimization of cooling system for future thermal management.

Abstract Fibrosis, a process caused by excessive deposition of extracellular matrix (ECM), is a common cause and outcome of organ failure and even death. Researchers have made many efforts to understand the mechanism of fibrogenesis and to develop therapeutic strategies; yet, the outcome remains unsatisfactory. In recent years, advances in epigenetics, including chromatin remodeling, histone modification, DNA methylation, and noncoding RNA (ncRNA), have provided more insights into the fibrotic process and have suggested the possibility of novel therapy for organ fibrosis. In this review, we summarize the current research on the epigenetic mechanisms involved in organ fibrosis and their possible clinical applications. Graphical Abstract

Abstract Skin fibrosis, a pathological process featured by fibroblast activation and extracellular matrix (ECM) deposition, makes a significant contribution to morbidity. Studies have identified biomechanics as the central element in the complex network of fibrogenesis that drives the profibrotic feedback loop. In this study, we found that the acetylation of α‐tubulin at lysine 40 (K40) was augmented in fibrotic skin tissues. Further analysis showed that α‐tubulin acetylation is required for fibroblast activation, including contraction, migration, and ECM deposition. More importantly, we revealed that biomechanics‐induced upregulation of K40 acetylation promotes fibrosis by mediating mechanosensitive Yes‐associated protein S127 dephosphorylation and its cytoplasm nucleus shuttle. Furthermore, we demonstrated that the knockdown of α‐tubulin acetyltransferase 1 could rescue the K40 acetylation upregulation caused by increased matrix rigidity and ameliorate skin fibrosis both in vivo and in vitro. Herein, we highlight the critical role of α‐tubulin acetylation in matrix stiffness‐induced skin fibrosis and clarify a possible molecular mechanism. Our research suggests α‐tubulin acetylation as a potential target for drug design and therapeutic intervention.

Abstract Background Hepatic arterial infusion chemotherapy (HAIC) with oxaliplatin and 5-fluorouracil was effective in unresectable hepatocellular carcinoma (HCC). The program of FOLFOX-HAIC in HCC was performed for 1 day (HAIC 1d) or 2 days (HAIC 2d). We hereby retrospectively compared the efficacy and safety between these two treatment regimens and explored the predictive power of thymidylate synthase (TYMS), an enzyme involved in the DNA synthesis process and metabolism of fluorouracil. Methods This study included patients with a primary diagnosis of unresectable HCC. These patients received HAIC for 1 day or 2 days. The overall survival (OS), progression-free survival (PFS), tumor response, and adverse events were compared. The propensity score matching (PSM) was used to reduce bias. Peripheral blood samples before the treatments were collected and used to measure the concentration of TYMS through enzyme-linked immunosorbent assay (ELISA). ELISA was performed according to the manufacturers’ guidelines. Results We included 368 patients for this study: 248 in the HAIC 1d group and 120 in the HAIC 2d group. There was no significant difference of OS between the two groups (14.5 for HAIC 1d vs 15.3 months for HAIC 2d, p=0.46). Compared with the HAIC 1d group, the HAIC 2d group did not prolong the PFS (7.3 vs 7.5 months, p=0.91) or elevate the tumor response (42.5% vs 39.1%, p=0.53) per RECIST 1.1. In the PSM cohort, the efficacy between the two groups was similar. The total frequencies of grade 3–4 events were higher with the HAIC 2d group than with the HAIC 1d group, especially in the PSM cohort (p=0.043). Additionally, patients with TYMS low level might benefit longer OS from the HAIC 2d group (18.7 vs 13.6 months, p=0.014). Conclusions There was not much of a difference in efficacy between the two groups, but the HAIC for 1 day might be safer, which needed further research. The level of TYMS might be the predictive biomarkers.

Hepatocellular carcinoma (HCC) is highly heterogeneous. Molecular subtyping for guiding immunotherapy is warranted. Previous studies have indicated that enhancer RNAs (eRNAs) are involved in tumor heterogeneity and immune infiltration. However, the eRNA landscape and its correlation with immune infiltration in HCC remain unknown. Here we first revealed the genome-wide eRNA landscape in two HCC cohorts. Then we divided individuals with HCC into three immune-related clusters (C1, C2, and C3) based on eRNA expression profiles. The prognosis, biological properties, immune infiltration, clinical features, genomic features, and drug response were analyzed. C1 was enriched in immune infiltration and potentially sensitive to immune checkpoint inhibitors (ICIs). C2 displayed features of immune depletion, high proliferation activity, malignant clinical features, and the worst prognosis. C2 may benefit from targeted therapy. C3 presented moderate immune infiltration, metabolism-related signatures, and the best prognosis. Transarterial chemoembolization (TACE) may be effective for C3. Finally, we constructed a 51-eRNA classifier for subtype prediction and validated its efficacy in The Cancer Genome Atlas (TCGA) cohort and Sun Yat-sen University Cancer Center (SYSUCC) cohort. Our results provide a novel method for immune classification of HCC, shed new light on tumor heterogeneity, and may aid in HCC immunotherapy.

Skin fibrosis is a physiopathological process featuring the excessive deposition of extracellular matrix (ECM), which is the main architecture that provides structural support and constitutes the microenvironment for various cellular behaviors. Recently, increasing interest has been drawn to the relationship between the mechanical properties of the ECM and the initiation and modulation of skin fibrosis, with the engagement of a complex network of signaling pathways, the activation of mechanosensitive proteins, and changes in immunoregulation and metabolism. Simultaneous with the progression of skin fibrosis, the stiffness of ECM increases, which in turn perturbs mechanical and humoral homeostasis to drive cell fate toward an outcome that maintains and enhances the fibrosis process, thus forming a pro-fibrotic “positive feedback loop”. In this review, we highlighted the central role of the ECM and its dynamic changes at both the molecular and cellular levels in skin fibrosis. We paid special attention to signaling pathways regulated by mechanical cues in ECM remodeling. We also systematically summarized antifibrotic interventions targeting the ECM, hopefully enlightening new strategies for fibrotic diseases.

Abstract Background Prognostic assessment is imperative for clinical management of patients with hepatocellular carcinoma (HCC). Most reported prognostic signatures are based on risk scores summarized from quantitative expression level of candidate genes, which are vulnerable against experimental batch effects and impractical for clinical application. We aimed to develop a robust qualitative signature to assess individual survival risk for HCC patients. Methods Long non-coding RNA (lncRNA) pairs correlated with overall survival (OS) were identified and an optimal combination of lncRNA pairs based on the majority voting rule was selected as a classification signature to predict the overall survival risk in the cancer genome atlas (TCGA). Then, the signature was further validated in two external datasets. Besides, biomolecular characteristics, immune infiltration status, and chemotherapeutics efficacy of different risk groups were further compared. Finally, we performed key lncRNA screening and validated it in vitro. Results A signature consisting of 50 lncRNA pairs (50-LPS) was identified in TCGA and successfully validated in external datasets. Patients in the high-risk group, when at least 25 of the 50-LPS voted for high risk, had significantly worse OS than the low-risk group. Multivariate Cox, receiver operating characteristic (ROC) curve and decision curve analyses (DCA) demonstrated that the 50-LPS was an independent prognostic factor and more powerful than other available clinical factors in OS prediction. Comparison analyses indicated that different risk groups had distinct biomolecular characteristics, immune infiltration status, and chemotherapeutics efficacy. TDRKH-AS1 was confirmed as a key lncRNA and associated with cell growth of HCC. Conclusions The 50-LPS could not only predict the prognosis of HCC patients robustly and individually, but also provide theoretical basis for therapy. Besides, TDRKH-AS1 was identified as a key lncRNA in the proliferation of HCC. The 50-LPS might guide personalized therapy for HCC patients in clinical practice.

Endurance is a critical factor for solar-powered unmanned aerial vehicles (SUAVs). Taking inspiration from birds, SUAVs have the ability to harvest extra energy from atmospheric thermal updrafts to extend their endurance. Though recent research has mainly focused on estimating the characteristics of thermal updrafts, there is a noticeable dearth of studies investigating the energy performance of SUAVs during soaring under different conditions. To begin with, this work establishes a thermal updraft and SUAV energy model. In addition, it introduces an integrated guidance and control process to achieve static soaring within thermal for SUAVs. Numerical simulations are implemented to analyze the electric energy performance at different solar irradiation levels, SUAV velocities and thermal strengths. Several remarkable conclusions are drawn from the simulations, which could provide significant insights for SUAVs to further exploit thermal energy.

Purpose: Sorafenib is recommended for patients with hepatocellular carcinoma refractory to transarterial chemoembolization but with unsatisfactory overall survival and tumor response rate. Previously published studies showed hepatic arterial infusion chemotherapy of oxaliplatin, fluorouracil, and leucovorin was an effective and safe treatment. The aims of this study were to compare the clinical efficacy and safety of oxaliplatin, fluorouracil, and leucovorin-based hepatic arterial infusion chemotherapy with sorafenib in patients with hepatocellular carcinoma refractory to transarterial chemoembolization. Methods: This was a retrospective subgroup analysis of 2 prospective clinical trials, including 114 patients with hepatocellular carcinoma who were confirmed to be transarterial chemoembolization refractoriness. Of these, 55 patients received hepatic arterial infusion chemotherapy of fluorouracil, and leucovorin (FOLFOX-HAIC group, oxaliplatin 85 or 130 mg/m 2 , leucovorin 400 mg/m 2 , fluorouracil bolus 400 mg/m 2 , and 2400 mg/m 2 for 23 or 46 h, every 3 weeks), and 59 patients were treated with sorafenib (sorafenib group, 400 mg sorafenib twice daily). Overall survival, progression-free survival, objective response rate, and treatment-related adverse events were compared between the 2 groups. Results: The FOLFOX-HAIC group showed a longer overall survival (17.1 months [95% confidence interval 13.4-20.8] vs 9.1 months [95% confidence interval 7.5-10.6]; hazard ratio 0.35 [95% confidence interval 0.23-0.53]; P

A novel Cr (VI) removal material was designed and produced comprising multi-walled carbon nanotubes (MWCNTs) as a support with a high specific surface area and the loaded Fe–Ni bimetallic particles as catalytic reducing agents. Such a design permits the composite particle to perform the adsorption, reduction, and immobilisation of Cr (VI) quickly and efficiently. Due to MWCNTs’ physical adsorption, Cr (VI) in solution aggregates in the vicinity of the composite, and Fe rapidly reduces Cr (VI) to Cr (III) catalysed by Ni. The results demonstrated that the Fe–Ni/MWCNTs exhibits an adsorption capacity of 207 mg/g at pH = 6.4 for Cr (VI) and 256 mg/g at pH 4.8, which is about twice those reported for other materials under similar conditions. The formed Cr (III) is solidified to the surface by MWCNTs and remains stable for several months without secondary contamination. The reusability of the composites was proven by retaining at least 90% of the adsorption capacity for five instances of reutilization. Considering the facile synthesis process, low cost of raw material, and reusability of the formed Fe–Ni/MWCNTs, this work shows great potential for industrialisation.

Fibrosis, a pathologic process featured by the excessive deposition of connective tissue components, can affect virtually every organ and has no satisfactory therapy yet. Fibrotic diseases are often associated with organ dysfunction which leads to high morbidity and mortality. Biomechanical stmuli and the corresponding cellular response havebeen identified in fibrogenesis, as the fibrotic remodeling could be seen as the incapacity to reestablish mechanical homeostasis: along with extracellular matrix accumulating, the physical property became more “stiff” and could in turn induce fibrosis. In this review, we provide a comprehensive overview of mechanoregulation in fibrosis, from initialing cellular mechanosensing to intracellular mechanotransduction and processing, and ends up in mechanoeffecting. Our contents are not limited to the cellular mechanism, but further expand to the disorders involved and current clinical trials, providing an insight into the disease and hopefully inspiring new approaches for the treatment of tissue fibrosis.

The occurrence of aircraft icing can significantly affect flight performance. One of the most important aspects in the study of anti-icing technology for aircraft is the distribution of overflow water. Owing to the external airflow pressure, shear stress, and surface tension, the water film breaks up to form steady rivulets. Experiments on NACA0012 airfoil surfaces were conducted based on an open straight-flow and low-speed wind tunnel. Simultaneously, an engineered three-dimensional rivulet model considering the surface roughness was established based on the energy-minimum principle. A comparison between the simulation and experimental results shows that the errors in the water film breakup location and the flow velocity of rivulets are less than 20%, and the errors in the spacing and width of rivulets are less than 40%. In addition, the effects of surface temperature and uniform roughness on water film breakup were investigated. Furthermore, the rivulet model was applied to the numerical calculation of the thermal performance of hot-air anti-icing systems. The simulations reveal that the uniform roughness of the wing surface causes the water film to break earlier. As the surface roughness increases, the thickness, spacing, and width of the rivulets increase, and the rivulet flow velocity decreases.

A deep understanding of surface catalysis recombination characteristics is significant for accurately predicting the aeroheating between hypersonic non-equilibrium flow and thermal protection materials, while a de-coupling sensitivity analysis of various influential factors is still lacking. A gas–solid interface (GSI) model with a hyperthermal flux boundary was established to investigate the surface catalysis recombination mechanisms on nanoscale silica surfaces. Using the reactive molecular dynamics (RMD) simulation method, the effects of solid surface temperature, gas incident angle, and translational energy on the silica surface catalysis recombination were qualified under hyperthermal atomic oxygen (AO), atomic nitrogen (AN), and various AN/AO gas mixtures’ influence. It can be found that, though the Eley–Rideal (E–R) recombination mechanism plays a dominant role over the Langmuir–Hinshelwood (L–H) mechanism for all the sensitivity analyses, a non-linear increasing pattern of AO recombination coefficient γO2 with the increase in incident angle θin and translational energy Ek is observed. Compared with the surface catalysis under hyperthermal AO impact, the AN surface adsorption fraction shows an inverse trend with the increase in surface temperature, which suggests the potential inadequacy of the traditional proportional relationship assumptions between the surface adsorption concentration and the surface catalysis recombination coefficient for other species’ impact instead of AOs. For the incoming bi-component AO/AN gas mixtures, the corresponding surface catalysis coefficient is not the simple superposition of the effects of individual gases but is affected by both the intramolecular bond energies (e.g., O2, N2) and intermolecular energies (e.g., Si/N, Si/O).

Abstract Over the past half century, a variety of computational fluid dynamics (CFD) methods and the direct simulation Monte Carlo (DSMC) method have been widely and successfully applied to the simulation of gas flows for the continuum and rarefied regime, respectively. However, they both encounter difficulties when dealing with multiscale gas flows in modern engineering problems, where the whole system is on the macroscopic scale but the nonequilibrium effects play an important role. In this paper, we review two particle-based strategies developed for the simulation of multiscale nonequilibrium gas flows, i.e., DSMC-CFD hybrid methods and multiscale particle methods. The principles, advantages, disadvantages, and applications for each method are described. The latest progress in the modelling of multiscale gas flows including the unified multiscale particle method proposed by the authors is presented.

With the development of the autopilot system, the main task of a pilot has changed from controlling the aircraft to supervising the autopilot system and making critical decisions. Therefore, the human–machine interaction system needs to be improved accordingly. A key step to improving the human–machine interaction system is to improve its understanding of the pilots’ status, including fatigue, stress, workload, etc. Monitoring pilots’ status can effectively prevent human error and achieve optimal human–machine collaboration. As such, there is a need to recognize pilots’ status and predict the behaviors responsible for changes of state. For this purpose, in this study, 14 Air Force cadets fly in an F-35 Lightning II Joint Strike Fighter simulator through a series of maneuvers involving takeoff, level flight, turn and hover, roll, somersault, and stall. Electro cardio (ECG), myoelectricity (EMG), galvanic skin response (GSR), respiration (RESP), and skin temperature (SKT) measurements are derived through wearable physiological data collection devices. Physiological indicators influenced by the pilot’s behavioral status are objectively analyzed. Multi-modality fusion technology (MTF) is adopted to fuse these data in the feature layer. Additionally, four classifiers are integrated to identify pilots’ behaviors in the strategy layer. The results indicate that MTF can help to recognize pilot behavior in a more comprehensive and precise way.

The accurate calculation of energy system parameters makes a great contribution to the long-term low-altitude flight of solar-powered aircraft. The purpose of this paper is to propose a design method for optimization and management of the low-altitude and long-endurance Unmanned Aerial Vehicles (UAV) energy system. In terms of optimization, the power input and output generated by solar panels and cruise thrust are calculated, and the energy balance of the UAV during flight is analyzed. In addition, in order to meet the energy consumption requirements of UAV during day and night flight, the influence of local environmental conditions (such as morning and evening clouds and night interference) on the aircraft is considered, and the remaining time indicator is designed to ensure long-term flight stability. Battery capacity is also estimated by the remaining time. This paper will describe extended criteria for optimization and extension methods to improve the stability and robustness of aircraft flight performance for multiple consecutive days. In addition, a design method for the UAV has been developed, which simulates and optimizes the parameters of the solar-powered UAV so that it has a wingspan of 5 m and a relative battery mass of 3 kg. The simulation in this paper describes in detail the aircraft taking off from 7 a.m. on the first day to verify the aircraft’s full day and night flight capability, and achieving the aircraft’s long flight on 22 June to meet the mission requirements of multi-day flights. It also analyzed and verified the performance at the edge of the 48 h flight time window on 21 April, which differs from the lighting in August. Finally, a flight experiment was completed on 9 August. The feasibility of the proposed method and process is verified in this paper along with the performance of the designed UAV, which will provide more guidance for future work.

The airfoil is the prime component of flying vehicles. For low-speed flights, low Reynolds number airfoils are used. The characteristic of low Reynolds number airfoils is a laminar separation bubble and an associated drag rise. This paper presents a framework for the design of a low Reynolds number airfoil. The contributions of the proposed research are twofold. First, a convolutional neural network (CNN) is designed for the aerodynamic coefficient prediction of low Reynolds number airfoils. Data generation is discussed in detail and XFOIL is selected to obtain aerodynamic coefficients. The performance of the CNN is evaluated using different learning rate schedulers and adaptive learning rate optimizers. The trained model can predict the aerodynamic coefficients with high accuracy. Second, the trained model is used with a non-dominated sorting genetic algorithm (NSGA-II) for multi-objective optimization of the low Reynolds number airfoil at a specific angle of attack. A similar optimization is performed using NSGA-II directly calling XFOIL, to obtain the aerodynamic coefficients. The Pareto fronts of both optimizations are compared, and it is concluded that the proposed CNN can replicate the actual Pareto in considerably less time.

Abstract Cuttings transportation from the drill bit, through the annulus, to the surface is one of the most important functions performed by drilling fluid. The prediction of drilling fluid's performance to transport cuttings in the annulus is very complex task due to the presence of numerous parameters. Nanoparticles (NPs) have been recently introduced into drilling fluid to engineer its properties and enhance its performance. Nevertheless, the lifting capacity has not been sufficiently investigated. The understanding of the influence and the mechanisms responsible for the improvement in cuttings transport process can further advance the application of NPs for drilling fluids. Computational fluid dynamics (CFD) is widely used as a numerical technique in handling complex multiphase flow problems in different operational conditions. The present work has taken the advantages of CFD to computationally analyze the influence of NPs and the effects of various parameters such as drilling fluids rheology, flow rate, pipe rotation, cuttings density, shape, concentration, and drilling fluids‐cuttings particle coupling regimes on the cuttings transport in a vertical wellbore. The CFD simulation is carried out by using transient solver of ANSYS‐FLUENT commercial code. The dense discrete phase model is used to overcome the main shortcomings of previous Eulerian based approaches. Good agreement has been achieved between the simulation and the published experimental results. It showed that the fluid viscosity and cuttings transport process can be significantly enhanced by adding nanomaterials to the fluid, and the process is highly influenced by cuttings characteristics such as in situ concentration, shape, and density.

Shale heterogeneity has a significant effect on drilling and completions, hydraulic fracturing, as well as hydrocarbon development performance. However, it lacks representation of rock damage/failure caused by the mechanical heterogeneity and “stress shadow” effect during the hydraulic fracturing process. In this paper, the Galerkin finite element method was adopted to numerically simulate the hydro-mechanical coupled interaction based on the solver in the COMSOL Multiphysics software and Matlab scripting development. The Weibull probability density function was used to represent the mechanical heterogeneity of gas shale. Under the condition of fully fluid-solid coupling during the fracking process, the effect of mechanical heterogeneity on von – Mises stress, strain energy density, damage factor, and fluid pressure was numerically simulated in the gas shale wells. The curves of von – Mises stress, strain energy density, and damage factor along a certain straight line showed the obvious decreasing distribution in a completely homogeneous formation. As the strata are heterogeneously enhanced, their distribution curves showed fluctuations. Moreover, von – Mises stress and strain energy density had a good relationship with damage factors. Accordingly, the method of rock damage/fracture and ''stress shadow'' effect caused by mechanic heterogeneity was put forward under the circumstance of two–dimensional plane strain. That was to use, the von – Mises stress or strain energy density at the single point or line to characterize the degree of local rupture or the shadow effect of stress, and the average strain energy density per unit area to characterize the degree of rupture of the rock or the intensity of the shadow effect. The study is of great significance to further improve the SRV(Stimulated Reservoir Volume) fracturing design and the productivity of gas shale wells.

This paper presents a novel framework for the design of a low altitude long endurance solar-powered UAV for multiple-day flight. The genetic algorithm is used to optimize wing airfoil using CST parameterization, along with wing, horizontal and vertical tail geometry. The mass estimation model presented in this paper is based on structural layout, design and available materials used in the fabrication of similar UAVs. This model also caters for additional weight due to the change in wing airfoil. The configuration is optimized for a user-defined static margin, thereby incorporating static stability in the optimization. Longitudinal and lateral control systems are developed for the optimized configuration using the inner–outer loop strategy with an LQR and PID controller, respectively. A six degree-of-freedom nonlinear simulation is performed for the validation of the proposed control scheme. The results of nonlinear simulations are in good agreement with static analysis, validating the complete design process.

Silica nanoparticles have been shown to exhibit many characteristics that allow for additional oil to be recovered during sand-pack flooding experiments. Additionally various imaging techniques have been employed in the past to visually compare flooding procedures including x-ray computed tomography and magnetic resonance imaging; however, these techniques require the sample to be destroyed or sliced after the flooding experiment finishes. Electrical resistance tomography (ERT) overcomes these limitations by offering a non-destructive visualization method allowing for online images to be taken during the flooding process by the determination of spatial distribution of electrical resistivity, thus making it suitable for sand-packs. During the scope of this research a new sand-pack system and methodology was created which utilized ERT as a monitoring tool. Two concentrations, 0.5 wt% and 1.0 wt%, of SiO2 nanoparticles were compared with runs using only brine to compare the recovery efficiency and explore the ability of ERT to monitor the flooding process. Electrical resistance tomography was found to be an effective tool in monitoring local recovery efficiency revealing 1.0 wt% SiO2 to be more effective than 0.5 wt% and brine only runs during the scope of this research. A new method involving the slope function in excel was used to compare the effects of nanofluids on resistivity trends also revealing information about the rate of recovery against time. SiO2 nanofluid recovery mechanisms such interfacial tension reduction and viscosity enhancement were then considered to explain why the nanofluids resulted in greater oil recovery.

HITEC salt (NaNO2-NaO3-KNO3) and solar salt (NaO3-KNO3) are typical molten salts used in concentrated solar power. Adding nanoparticles is an effective method to improve the thermo-physical properties of pure salt. It is indispensable to experimentally study the rheological behaviours of salt seeded with nanoparticles, which can increase the specific heat capacity of pure salt. In this work, the viscosities of HITEC salt were measured with different shear rates in the temperature range of 200 °C to 450 °C firstly, while those of solar salt were measured in the temperature range of 250 °C to 500 °C. The experimental data showed reasonable agreement with the literature correlations, which verify the Newtonian behaviours of pure salts. The evolutions of the viscosities of nanocomposites in the same temperature range were measured and analysed, where the nanocomposites were synthesized with 1 wt.% or 2 wt.% Al2O3 nanopowder and graphene, respectively. Results showed that the addition of Al2O3 nanopowder had relatively little effect on viscosity, and the variations were about −35.4%~8.1% for the HITEC salt nanocomposites and −9.2%~68.1% for the solar salt nanocomposites. While graphene would apparently increase the viscosities of HITEC salt and solar salt, HITEC salt with the addition of graphene showed slight non-Newtonian fluid behaviour.

In order to support the future thermal control and energy conservation design for the Mars rover, numerical studies on natural convection in CO2 enclosures on Mars’ surface were conducted for both horizontal and vertical enclosures. The parameters are as follows: the atmospheric pressure was 1000 Pa, the gravitational acceleration was 3.62 m/s2, and the Prandtl number was 0.77. The heat flux, temperature, and velocity fields of the CO2 enclosures were obtained with the aspect ratio ranging from 5.56 to 200 and the Grashof number ranging from 430 to 2.6 × 104. It was found that natural convection formed more easily in the horizontal enclosures than that in the vertical enclosures when the enclosures had same thickness. With the increasing thickness of the enclosures, Rayleigh–Bénard convections formed in the horizontal enclosures, while only single-cell convections formed in the vertical enclosures. The heat flux through the horizontal enclosures was greater than that through the vertical enclosures with the same thickness when natural convection formed. The maximum difference between them reached 35.26%, which was illustrated by the field synergy principle. A hysteresis phenomenon of the natural convection dominating the heat transfer was found in the vertical enclosure on Mars’ surface. New values for the critical Grashof number and correlations for the average Nusselt number for both the horizontal and vertical CO2 enclosures on Mars’ surface were also developed.

The author wishes to correct Figure 1b in this paper [1][...]

Carbon nanoparticles (CNPs) are becoming promising candidates for oil/gas applications due to their biocompatibility and size-dependent optical and electronic properties. Their applications, however, are always associated with the flow of nanoparticles inside a reservoir, i.e., a porous medium, where insufficient studies have been conducted. In this work, we synthesized CNPs with two different size categories in 200 nm carbon balls (CNP-200) and 5 nm carbon dots (CNP-5), via a hydrothermal carbonation process. Comprehensive experiments in packed glass bead columns, as well as mathematical simulations, were conducted to understand the transport and deposition of CNPs under various ionic strength, particle sizes and concentration conditions. Our results show that the retention of CNP-200 is highly sensitive to the salinity and particle concentrations, while both of them are unaffected in the transport of small CNP-5. Supplemented with Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the clean bed filtration theory with blocking effect can successfully fit the experimental breakthrough curves of CNP-200. However, the high breakthrough ability for CNP-5 regardless of ionic strength change is in conflict with the energy interactions predicted by traditional DLVO theory.

We propose some reflections, comments and suggestions about the measurement of similar and matched content in scientific papers and documents, and the need to develop appropriate tools and standards for an ethically fair and equitable treatment of authors.

Seeding nanoparticles in molten salts has been shown recently as a promising way to improve their thermo-physical properties. The prospect of such technology is of interest to both academic and industrial sectors in order to enhance the specific heat capacity of molten salt. The latter is used in concentrated solar power plants as both heat transfer fluid and sensible storage. This work explores the feasibility of producing and dispersing nanoparticles with a novel one pot synthesis method. Using such a method, CuO nanoparticles were produced in situ via the decomposition of copper sulphate pentahydrate in a KNO3-NaNO3 binary salt. Analyses of the results suggested preferential disposition of atoms around produced nanoparticles in the molten salt. Thermal characterization of the produced nano-salt suspension indicated the dependence of the specific heat enhancement on particle morphology and distribution within the salts.