Steady Phase Research Articles

Intermediate temperature of supercritical water enhances the dispersion of cohesive particles

Supercritical water gasification represents a promising technology for the clean conversion of coal to hydrogen, so that it is expected to replace the traditional use of coal by burning. However, the flocculation of cohesive coal particles significantly reduces the contact area between particles and supercritical water, which limits the chemical reaction that produces hydrogen. Based on Lifshitz theory, we propose a cellular flow model for numerically reproducing the flocculation of cohesive particles in supercritical fluid turbulence. Cohesion, lubrication, and direct contact forces between particles are fully accounted for, so that the model allows us to conduct a detailed analysis of the translation, rotation, growth, and breakage of flocs in supercritical fluid turbulence. The results show a transient flocculation phase of cohesive particles characterized by an increasing average floc size, followed by a statistically steady equilibrium phase. Increasing the density ratio between particles and supercritical water significantly accelerates the flocculation of dispersed cohesive particles. Higher temperature of the fluid yields faster flocculation and larger flocs when the temperature is below the critical value of 660 K. Upon raising the temperature above 660 K, the flocculation rate and floc size first decrease, and then increase again, yielding an optimal temperature around 750 K where the primary particles are most effectively dispersed by the supercritical water turbulence.

Investigation of individual strategies in the aerial phase in ski jumping

The purpose of this investigation was to examine the performance strategy of three ski jumpers during the steady glide phase and explain how different strategical solutions can lead to jumps of roughly the same length. In this study, a total of 24 jumps performed by two World Cup (WC) athletes and one Continental Cup (COC) athlete were measured with a differential Global Navigation Satellite System (dGNSS) on a large ski jumping hill. For each athlete, the continuous position data, velocity, aerodynamic forces and lift-to-drag ratio (LD-ratio) were averaged and compared for the steady glide phase to examine individual jump strategies. The dGNSS yielded accurate measurements of trajectory, velocity and aerodynamic forces, revealing clear differences between the athletes. The largest differences were found between the WC athletes and the COC athlete. The WC athletes focused on maximizing horizontal velocity while the COC athlete minimized vertical velocity. This difference may be explained by the different hill sizes the athletes normally compete on. One of the WC athletes consistently increased their horizontal velocity during the end of the steady glide phase by maintaining a high LD-ratio, which highlights the effect of aerodynamics on the resulting velocity, trajectory and jump length.

Spectral wear modelling of rubber friction on a hard substrate with large surface roughness

Soft-hard matter friction is a long-standing tribology problem that remains unclarified, requiring engineers to empirically predict the wear life. To clarify this issue, this study examines the transient running-in regime of rubber friction on a hard rough substrate and models the temporal wear progression using the spectrum curves of surface roughness for both materials. Performing a series of friction tests and three-dimensional surface-height measurements, the time-dependent behaviours of the power spectral densities (PSDs) are divided into two phases, namely the initial non-steady and long-term steady phases. The detailed spectral analyses of worn rubber surfaces in the initial phase lead to a blended PSD function between self-affine and K -correlation surface models, consisting of one variable (the Hurst exponent) that is saturated by the substrate self-affinity. Supported by the Greenwood–Williamson theory concerning rough contact mechanics, the volumetric estimate with the blended PSD function is used to assess the volume rate of wear debris in the steady phase, which is validated experimentally. These findings not only improve the wear predictions of soft materials from the initial measurements of worn surfaces but also help clarify the constrained multiscale mechanism of wear.

Assessment of Circulating Retinol Binding Protein-4 Levels in Patients with Compound Heterozygosity for Hb S and β-Thalassemia

Background: Retinol Binding Protein-4 (RBP-4) is a member of the lipocalin family of proteins and the major transport protein of the hydrophobic molecule retinol, also known as vitamin A, in the circulation. Expression of RBP4 is highest in the liver, where most of the body's vitamin A reserves are stored as retinyl esters. For the mobilization of vitamin A from the liver, retinyl esters are hydrolyzed to retinol, which then binds to RBP-4 in the hepatocyte. After associating with transthyretin (TTR), the retinol/RBP-4/TTR complex is released into the bloodstream and delivers retinol to tissues via binding to specific membrane receptors. While, after its dissociation from TTR and retinol release, retinol-free apo-RBP4 in the circulation is filtrated by the kidney. More than 99% of that is reabsorbed by the proximal renal tubule, which renders urinary RBP-4 a highly sensitive marker for tubular dysfunction. We and other have shown previously that the patients with Sickle Cell Disease (SCD) have deficiencies or suboptimal levels of vitamin A, while recently (Br J Haematol. 2023;doi:10.1111/bjh.18862) higher urine RBP-4 in patients with SCD especially in those with persistent albuminuria but without an association of urine RBP-4 levels with estimated glomerular filtration rate (eGFR). In this context, we aimed to investigate the potential clinical significance of circulating plasma RBP-4 levels and its association with disease features in Caucasian patients with compound heterozygosity for HbS and β-thalassemia (HbS/β thal). Patients and Methods: Ninety Caucasian adult patients with HbS/β thal at steady phase were included in the study, while 22 apparently healthy individuals of similar age and gender served as controls. None of the patients was diabetic and has received any transfusions at least 6-monthes before enrollment in the study. RBP-4 concentration was measured with an immunoturbidimetric assay applied in an automated chemistry analyzer, along with hematologic, and series of blood chemistry parameters reflecting renal, cardiac and endothelial dysfunction. eGFR values were calculated using the CKD-EPI (Cystatin C and/or Creatinine equations). Results: We found that: a) Plasma RBP-4 levels were significantly lower in patients with HbS/β thal compared to controls, 30.5±2.7mg/L (Confidence Intervals (CI): 28.8;32.2mg/mL) vs 36.3±3.6mg/L (CI: 32.7;39.9mg/mL), p<0.003. The patients with β + genotypehave higher RBP-4 levels than those with β 0 genotype (p<0.05), whereas patients treated with hydroxycarbamide(50/90) are more likely to express higher RBP-4 levels, p-trend=0.06; b) RBP-4 levels in patients with HbS/β thal correlated positively with their age, body mass index (BMI) and Hb levels (r=0.264, p=0.012; r=0.334, p=0.001 and r=0.209, p<0.05, respectively; c) RBP-4 levels in patients with HbS/β thal correlated with total bilirubin, total cholesterol, triglycerides and uric acid (r=-0.452, p<0.001; r=0.395, p=0.004; r=0.292, p=0.015 and r=0.435, p<0.001, respectively); d) RBP-4 levels in patients with HbS/β thal correlated negatively with eGFR values rho=-0.360, p=0.003 and hs-CRP concentrations r=-0.309, p=0.004 and e) No correlations were found between RBP-4 levels with markers of cardiac and endothelial dysfunction such as High Sensitivity Troponin T, Growth Differentiation Factor-15, von Willebrand factor antigen, Α Disintegrin and Metalloproteinase with Thrombospondin Type 1 Motif 13 antigen and P-Selectin, as well as with number of vaso-occlusive crisis and mean pulmonary arterial pressure in the patients. Conclusions: These findings demonstrate a multifactorial role of RBP-4 in patients with HbS/β thal as the circulating levels of the protein correlate significantly with markers of erythropoiesis, inflammation and renal function. It is unclear of this study if RBP-4 has any specific functions in patients with HbS/β thal. However, RBP-4 should be more investigated in order to determine its clinical significance and in the case of sickle cell nephropathy both plasma and urine measurements should be considered.

Nanoscale friction analysis using asperity cross-section and longitudinal section area

This study investigates the effect of nanoscale asperity geometry and indentation depth on friction behaviors. Diamond asperities of cone, cosine, and hemisphere sliding on the copper substrate are analyzed based on asperity cross-section and longitudinal section area. Results show that asperity cross-section area is linear to friction force as the key component. Moreover, wear volume is decided by and linear to asperity longitudinal section area. The simulated results of wear volume present a slope agreement with the classical wear model in the steady phase with a shift at the beginning.

Energy-based cold-start strategies for diesel engines at extreme low temperature

The cold start of diesel engines at extreme low temperatures is currently one of the most critical problems in the field of transportation. An experiment on the cold start was conducted in a controlled environment, and a one-dimensional simulation model was built to study diesel engine cold start performance based on energy analysis. The cyclic energy loss of cold start failure and success cases, ramp-up-speed period characteristic of diesel engine were studied by using special low temperature diesel and adopting two pilots and one main injection control strategy at −43 ℃. The numerical calculation and analysis results show that when the exhaust energy is high and the heat transfer loss energy is very low, there may be a misfire cycle in the cylinder. The increase in the pilot injection 1 mass, main injection mass, pilot injection 1 timing, and main injection timing within certain limits can significantly increase the fuel vapor fraction during the ramp-up-speed period (maximum of 66.67%). The speed of ramp-up-speed period and idle steady phase faster obviously, the maximum increase is 300 r/min (30%). The fuel vapor fraction increases as the pilot injection 2 mass increases during the ramp-up-speed period but slows down the speed of ramp-up and idle phase, with a maximum decrease of 300 r/min (23.07%).

Structures and compositions of biofilms in moving bed biofilm reactors pretreated by four drying methods

Research has so far paid little attention to the impact of the drying method on the structural and compositional analyses of biofilms from moving bed biofilm reactors (MBBRs). To ensure that the biofilm was derived from a steady operation phase of the MBBR, in this study, stable values of the chemical oxygen demand (COD), PO43-, total nitrogen (TN), ammonia–nitrogen (NH4-N), NO3-N and NO2-N concentration, and the biofilm dry weight were obtained after 22 d of operation. Four drying methods (supercritical CO2 drying, vacuum freeze-drying, heat drying, and natural drying) were used to pretreat the biofilms, and the changes in biofilm structures and compositions were investigated in detail. The supercritical CO2 drying and vacuum freeze-drying both maintained the biofilm compositions, while vacuum freeze-drying increased the average pore diameter of the biofilm more than five times that of the biofilm obtained by supercritical CO2 drying. In addition, heat drying and natural drying both damaged the structures and compositions of the biofilms, and heat drying in particular could cause structural collapse, surface charge declines of at least 20%, C and N elemental losses, and biomacromolecule (proteins, polysaccharides, and lipids) losses. The results from this investigation will aid in elucidating the appropriate drying methods for analyzing biofilm structures and compositions.

Interpreting phase shifts of basin-scale arrivals observed in the North Pacific

The 75 Hz Kauai Beacon is well situated for observing the North Pacific Ocean acoustically. Somewhat conveniently, three ocean observing networks, with acoustic receivers located within the deep sound channel: two observatories 4 mm to the East (RCO: Regional Cabled Observatory and MARS: Monterey Accelerated Research System), and the International Monitoring Station at Wake Island 3.5mm to the West. During April–June of 2023, the Beacon transmitted a 37.5 Hz bandwidth m-sequence signal several times a day every 4 days. Upon processing, a persistent arrival structure is identified, which for which each arrival exhibits a unique, yet relatively steady phase over the course of a 20-min transmission. Leveraging acoustic propagation models to better understand the effect of the fluctuating ocean environment, we address the stability of the arrivals over the 20-min transmissions, from hour to hour, and over the course of the 3-month study. This includes examination of potential causes for the slow-phase shifts observed at all of the stations, and how it relates to Doppler. This talk concludes with a discussion on the future utility and research topics of interest, including long-range geo-positioning (underwater GPS), communications, thermometry, and tomography.

Creep properties and constitutive model of salt rocks under a slow cyclic loading path

The construction of compressed-air energy storage (CAES) plants using the huge space created by salt rock mining is a key means of optimizing China's energy structure. The creep properties of salt rock are vital parameters for ensuring the long-term, stable operation of CAES plants. According to the operation mode of CAES plants, creep tests were conducted on salt rock under the influence of slow loading and unloading. The results indicated that the slow loading and unloading history locally changed the creep development process but did not affect the overall creep process. Additionally, the steady state creep rate of the salt rock depended mainly on the magnitude of external stress. Moreover, the creep test was monitored simultaneously using acoustic emission (AE) technology, and the distribution of the AE absolute energy during the initial loading phase and steady state creep phase satisfied the power law. To more accurately describe the creep characteristics of the salt rock under the influence of slow loading and unloading, a full-process creep constitutive model of salt rock was constructed using state variable, fracture expansion factor, and unloading factor.

Preliminary characterization and thermal evaluation of a direct contact cascaded immiscible inorganic salt/high-density polyethylene as moderate temperature heat storage material

The present work assesses the direct contact cascaded immiscible phase change material (PCM) for solar heat storage systems (SHSS) in water heating applications. The direct contact cascaded immiscible PCM uses ternary salt mixture (TSM) and high-density polyethylene (HDPE). Improvement on phase behavior and thermal properties are obtained for the direct contact cascaded immiscible TSM/HDPE. The plasticity effect of HDPE leads to a stable phase transition of the mixture with the lowest supercooling degree by 0.9 °C. The initial thermal decomposition temperature for TSM and HDPE is above 400 °C, which is suitable for moderate temperature operation of SHSS. The immiscibility between TSM and HDPE leads to a multistep phase transition between 110.2 and 139.6 °C. The phase behavior during the liquid-solid transition demonstrates the lowest temperature gradient of 13.9 °C, implying a steady phase transition. It allows the stored heat can be released effectively without causing significant volume expansion of the TSM. Moreover, the enthalpy of fusion for TSM/HDPE is increased, making it favorable as solar thermal energy for water heating applications in SHSS.

基于自适应模糊神经网络算法（ANFIS）的生物质原料颗粒密度预测

Coconut coir dust and corn stover powder were taken as raw biomass materials for pellet production, using four uni-axial compression set-ups, to explore the influence of the diameter of the inner hole diameter of the cylinder, the depth in compression , and the depth remained in compaction on the pellet density. Sample of pellets produced at the force steady phase, the maximum pellet density of the coconut coir dust material is 1.53 g/cm3 (1530 kg/m3), and 1.23 g/cm3 (1230 kg/m3) of the corn stalk powder pellets are obtained, At the same time, in the process of the test, Failure to compress the two biomass raw materials into pellets also occurred, indicating that the compression parameters studied in the experiment had a significant impact on the pellet quality. On the basis of the obtained pelleting test data, taking into account the nonlinear characteristics between pellet density and processing parameters involved, the adaptive neuro-fuzzy influence system(ANFIS) method was used to predict the pellet density of coconut coir dust and corn stover powder. The results show that the method is effective for predicting the density of biomass particles.

Effects of creep age forming time on microstructure and high cyclic fatigue of 7075 aluminum alloy

AbstractIn this paper, the hardness, ultimate tensile strength, yield strength, elongation E100, S−N curves, and fatigue performance of 7075 aluminum alloy were obtained after aged at 170 °C for different times (10 h, 15 h, and 20 h). Additionally, the microstructure and fatigue fracture of the alloy were observed. The investigation results show that as the forming time increased, the hardness, ultimate tensile strength, and yield strength decreased, the elongation first decreased, then increased, and the fatigue limit increased. As the forming time increased, the metastable phase gradually transformed into a steady phase and coarsened, the width of precipitate free zone increased, and the width of the fatigue strip decreased. After creep age forming for 20 h, the precipitate free zone was the widest, approximately 100 nm.

Experimental study of Gas-To-Liquid (GTL) and diesel fuel blends evaporation behaviour and droplet lifetime through Leidenfrost effect

Gas to Liquid (GTL) fuel is considered a clean alternative fuel and has been given much attention to replacing conventional fuel. Evaporation behaviour and droplet lifetime are critical aspects that need to be determined as these aspects can affect the fuel spray properties and improve the combustion process. In this study, a set of GTL–diesel fuel blends are prepared, which are G20, G50, G80, and G100 (the number represents the GTL percentage fuel ratio in the fuel blends). Subsequently, using a single droplet drop test on the hot plate (Leidenfrost effect), the GTL fuel blends droplet lifetime and evaporation behaviour are visualised using a high-speed camera connected to long-distance microscopy. An image processing system and a MatLab were used to measure and analyse the droplet evaporation data. Comparing the fuel characterisation of the GTL fuel and conventional diesel fuel, the GTL fuel shows a lower value in all properties tested except for the calorific value, cetane number, and vapour pressure. The qualitative results through the Leidenfrost effect have shown that increasing the GTL fuel ratio (20% to 100%) decreases the heating phase duration (37.3 % to 14.4 %) and evaporation rate (1.29 mm 2/s to 1.10 mm 2/s) while increasing their steady evaporation phase duration and droplet lifetime. The shorter period to achieve steady evaporation is beneficial as the spray inside the chamber has a limited time to evaporate for combustion.

Combustion behavior of electrically controlled solid propellant with tungsten additive

In recent times, there is a growing interest in utilizing the controllable solid propellant combustion that facilitates multiple start and stop bits of the electrically controlled solid propellant (ECSP) combustion at will. This paper is an attempt to understand the effect of tungsten metal additive in the ECSP. The tungsten metal powder (1 μm size) is blended with the lithium perchlorate (LP) and polyvinyl alcohol (PVA) along with other ingredients. LP and PVA form the baseline composition, and metal content is added between 5 and 15% by weight. Thermal analysis of the ECSP samples were conducted at 5 °C/min utilizing differential scanning calorimetry (DSC) and thermogravimetry (TGA) in the temperature range of 30 °C–600 °C, and the results showed that the dominant exothermic peaks occur around 260 °C. High speed imaging facilitates in understanding the combustion characteristics of the ECSP samples. The ignition is achieved by applying 300 V DC supply across the molybdenum electrodes. ECSP combustion can be divided into two distinct phases of burning that can be designated as the transient burning and the steady phase burning. It is found that the burning rate was 38.2% faster for 15%-metalized ECSP than 5%-metalized. In addition, multi-wavelength pyrometry was used to obtain the average flame temperature, and it was observed that the flame temperature was 9% lower for 15%-metalized than 5%-metalized. Hence, this study enunciates the burning characteristics of tungsten based ECSP and helps in realizing the potential use of tungsten as a metal additive in the ECSP for micro thrust generation.

Investigating toothbrushing behavior and its aerosol emissions from using electric toothbrushes

Respiratory infectious diseases (RIDs) are generally spread through person-to-person contact. The human oral cavity, in particular, is a significant source of particles that can cause RIDs. Electric toothbrushes, popular for oral cleaning in recent years, work via high-frequency vibration, which can theoretically spread droplets or small-size aerosols containing viruses. However, the particle emission rates and the potential to spread RIDs using electric toothbrushes are still unclear. In this paper, we investigated the particle emissions from using electric toothbrushes by designing a three-step approach, i.e., a preference survey on toothpaste and toothbrush selections, a behavior test on toothpaste usage, and a standardized particle emission test. The results showed that, first, the toothpaste would be rapidly decomposed into foams, and the emission rates quickly increased to a peak within approximately 10s. Then, the particle emissions decreased slightly and entered a steady phase until the 2-min brushing period stopped. Second, more than half of the detected particles were PM1, and almost all were PM5, which can be considered aerosols, and the emissions can reach up to 5433 counts/s. Third, the emissions heavily depended on toothbrush and toothpaste selections, the brushing post, i.e., the teeth. This study suggests that using electric toothbrushes can pose risks of spreading RIDs in enclosed indoor environments such as private homes or, more significantly, public washrooms in school dormitories, airports, train stations, etc. Limited usage of electric toothbrushes and better designs of public washrooms in the context of a global pandemic may be advised.

Characteristic enhancement of RV reducer under non-stationary condition based on WDT-IF-SS-VMD

Because the working conditions of the rotate vector (RV) reducer are often reciprocating at variable speeds and the working environment is relatively complex, so the vibration signals collected have non-stationary vibration and complex environmental noise. A fault diagnosis method for RV reducer (WDT-IF-SS-VMD) is proposed, which combines instantaneous frequency (IF) trend graph based on current signal and the parameter adaptive variational mode decomposition (VMD) algorithm. Firstly, the current signal and vibration signal are collected synchronously, and the steady-state phase of vibration signal is intercepted according to the IF trend diagram obtained by wavelet decomposition transform (WDT) of the current signal. Secondly, the intercepted vibration signals are transformed into scale space, and the parameters of VMD are selected adaptively based on fuzzy C-means clustering. Then, the maximum kurtosis criterion is used to complete the extraction of sensitive components. Finally, the envelope analysis is carried out to complete the fault diagnosis. The measured signal analysis results show that this method can effectively separate and extract fault features of the RV reducer.

Born this way: thin disc, thick disc, and isotropic spheroid formation in FIRE-2 Milky Way–mass galaxy simulations

ABSTRACT We investigate the formation of Milky Way–mass galaxies using FIRE-2 ΛCDM cosmological zoom-in simulations by studying the orbital evolution of stars formed in the main progenitor of the galaxy, from birth to the present day. We classify in situ stars as isotropic spheroid, thick-disc, and thin-disc according to their orbital circularities and show that these components are assembled in a time-ordered sequence from early to late times, respectively. All simulated galaxies experience an early phase of bursty star formation that transitions to a late-time steady phase. This transition coincides with the time that the inner CGM virializes. During the early bursty phase, galaxies have irregular morphologies and new stars are born on radial orbits; these stars evolve into an isotropic spheroidal population today. The bulk of thick-disc stars form at intermediate times, during a clumpy-disc ‘spin-up’ phase, slightly later than the peak of spheroid formation. At late times, once the CGM virializes and star formation ‘cools down,’ stars are born on circular orbits within a narrow plane. Those stars mostly inhabit thin discs today. Broadly speaking, stars with disc-like or spheroid-like orbits today were born that way. Mergers on to discs and secular processes do affect kinematics in our simulations, but play only secondary roles in populating thick-disc and in situ spheroid populations at z = 0. The age distributions of spheroid, thick disc, and thin disc populations scale self-similarly with the steady-phase transition time, which suggests that morphological age dating can be linked to the CGM virialization time in galaxies.

Influence of Nitrite on the Removal of Organic Matter and Manganese Using Pilot-Scale Biofilter: A Kinetic Study

Nitrite produced during ammonia oxidation can inhibit the activity of microorganisms. To provide guidance for the optimization and design of a biofilter, a pilot-scale biofilter was established to investigate the influence of nitrite on organic matter and manganese removal and on the kinetics. The results demonstrated that CODMn, ammonia, and manganese in effluent were 2.77, 0.034, and 0.026 mg/L in the steady phase, respectively. Organic matter and manganese removal were affected by nitrite during the start-up process, as well as in the ammonia increasing process. When ammonia increased from about 0.5 to 1 and 2 mg/L, organic matter, and manganese removal were affected at 4 and 3 days and 6 and 5 days, respectively. When organic matter, ammonia, and manganese in the influent were 6.27, 2.07, and 1.19 mg/L, respectively, organic matter, ammonia, and manganese oxidation all followed a first-order kinetic rate. The k-value was 0.0268, 0.268, and 0.216 min−1, and the half-life time was 24.236, 2.583, and 3.202 min, respectively. The influence of nitrite on the structure of microbial communities in the biofilter will be investigated in the future.

The Glasgow declaration on sustainability in Anaesthesiology and Intensive Care.

The Glasgow declaration on sustainability in Anaesthesiology and Intensive Care.

Bladder Cancer Cells Interaction with Lectin-Coated Surfaces under Static and Flow Conditions.

Aberrant expression of glycans, i.e., oligosaccharide moiety covalently attached to proteins or lipids, is characteristic of various cancers, including urothelial ones. The binding of lectins to glycans is classified as molecular recognition, which makes lectins a strong tool for understanding their role in developing diseases. Here, we present a quantitative approach to tracing glycan-lectin interactions in cells, from the initial to the steady phase of adhesion. The cell adhesion was measured between urothelial cell lines (non-malignant HCV29 and carcinoma HT1376 and T24 cells) and lectin-coated surfaces. Depending on the timescale, single-cell force spectroscopy, and adhesion assays conducted in static and flow conditions were applied. The obtained results reveal that the adhesion of urothelial cells to two specific lectins, i.e., phytohemagglutinin-L and wheat germ agglutinin, was specific and selective. Thus, these lectins can be applied to selectively capture, identify, and differentiate between cancer types in a label-free manner. These results open up the possibility of designing lectin-based biosensors for diagnostic or prognostic purposes and developing strategies for drug delivery that could target cancer-associated glycans.