Rise Height Research Articles

Study of deposition temperature effect on spray-deposited copper oxide thin films and its schottky diodes

Due to its ideal optical and electrical properties for upcoming electronic devices, Cu2O is commonly regarded as one of the most promising p-type oxides. Copper (Cu) rapidly deposits mixed phases of its oxides. This article describes the spray deposition method for developing copper oxide thin films at temperatures between 200 and 400 °C on glass substrates coated with ITO. Through optimization of the deposition temperature, Cu2O-rich phases were attained in the copper oxide films, typically around 300 °C. A Cu-rich phase was seen at 200 °C deposition temperature, and this phase progressively diminished at higher temperatures. At 400 °C, the CuO phase began to enrich the films in the meantime. Analysis using an x-ray diffraction (XRD) verified the existence of Cu2O phases (111), (200), and (220). The crystallites were discovered to be between 17.49 and 20.32 nm in size for the films deposited between 300 and 400 °C. The x-ray Photoelectron Spectroscopy (XPS) identifies Cu and oxygen as the main components. Furthermore, it is demonstrated that the deposition temperature significantly affects the copper’s oxidation state. The Atomic Force Microscopy (AFM) investigation showed that as the temperature increased, surface roughness decreased. As the deposition temperature increased, the energy band gap of the deposited films widened from 1.67 to 2.85 eV, as observed by the UV–vis-NIR spectrophotometer. Moreover, the fabrication of Schottky diodes with Cu metal contacts is also reported. These fabricated diodes showed a proportionate rise in barrier height with increasing deposition temperature.

Aging effect on surface chemistry and sorption properties of atmospheric pressure plasma treated lignocellulosic jute fibers

Jute fibers are characterized by a heterogeneous chemical composition (cellulose and non-cellulosic components) and a complex layered structure with a hydrophobic surface outer layer responsible for their low wettability. In this work, after the removal of water-soluble components, raw jute fibers were subjected to atmospheric pressure dielectric barrier discharge (DBD) under different conditions (at 150 or 300 Hz) to tailor jute fiber surface structure and wettability. The research was focused on the aging effect during natural aging in a standard atmosphere investigated up to three weeks after DBD treatment. Alterations in the surface morphology of DBD-treated jute fibers were investigated by FE-SEM and AFM, while ATR-FTIR, XPS, and electrokinetic measurements were used to assess the changes in the jute fiber surface chemistry. Sorption properties were monitored through wetting time and capillary rise measurements. The sorption properties of DBD-treated jute fibers were improved (about 100 times lower wetting time and 15 % higher capillary rise height in comparison to untreated) due to the changes in surface chemistry (decreased lignin and hemicellulose content in parallel with cellulose oxidation) and morphology (about 4.6 times higher average roughness). The electrokinetic and sorption properties measurement confirmed the significance of aging effects in lignocellulosic fibers' functionalization using plasma.

Research on Work Performance of Monolithic Precast Concrete Shear Walls with Post-Cast Epoxy Resin Concrete

Precast concrete structures are popular in the building industry because of their high efficiency and environmental friendliness. In this paper, the U-type reinforcement ferrule connection technique was applied to study the seismic performance of precast concrete shear walls. Five shear wall finite element models and four shear wall specimens were prepared. Both experiments and finite element analysis were conducted to explore the impact of parameters on the work performance of precast reinforced concrete shear walls, such as the variety of post-cast concrete, the form of horizontal joints, and the buckle length of U-type reinforcements. On this basis, the mechanism of failure as well as the characteristics of hysteresis, ductility, and energy dissipation capacity were analyzed. According to the analytical results, the cast in situ reinforced concrete shear wall is inferior to the precast shear wall with post-cast epoxy resin concrete in terms of seismic performance. In addition, the specimen with a keyway on the horizontal joint interface outperforms the specimen without a keyway. With an increase in the buckle length of the U-type reinforcement, there is a rise in the sectional height and stiffness of the hidden beam at the bottom of the wall, while the horizontal load-bearing capacity of the wall is improved. However, its ductility and energy dissipation capacity are decreased. As revealed by a thorough analysis, the construction scheme most suitable for precast shear wall horizontal joints adopts epoxy resin concrete as the post-cast material, the buckle length of U-type reinforcements is approximately one-third the height of the horizontal joint, and there is a keyway at the interface of the joint.

Spreading and Capillary Imbibition of Viscous Oil Lens into an Open-Cell Porous Structure.

Oil pollution in the ocean is becoming more and more of a serious issue, which increases interest in both ways for combating its cause and methods for observing and monitoring how oil spreads. A promising approach based on an optical method with empirical relations for selected viscous oil-water systems is presented. Based on a modified melamine sponge (MMS), the microscopic spreading and oil capillary penetration phenomenon of the porous structure were investigated. The objective of this study is 2-fold: (i) to present a more thorough experimental description of the spreading of viscous oil lens on the water surface and capillary action of oil lens into MMS porous structure; and (ii) to provide a theoretical description that helps to explain some of the observed behavior. With knowledge of , we can determine the spreading coefficient S. It needs to be pointed out that the oil lens floating on the water surface does satisfy Neumann's rule as the spreading coefficient of the air-oil-water system is negative (- 9.8 mN/m), indicating the ability to form a stable oil lens with thickness δO = 3.04 mm and radius RL = 38.64 mm after 60 min of spreading test. Furthermore, to better understand the capillary phenomena from a mechanical approach, an oil lens in contact with the surface of the MMS porous structure, by in-depth visualization, is properly defined as the balance of forces acting. Finally, as an illustration of this method, we utilized this approach to obtain the equilibrium height of the capillary rise and take it into account in terms of effective material thickness.

Justification of the Use of Container Technology in Dumping

The increase in the depth of the quarry is associated with an increase in the work of quarry transport in limited areas, requires a constant increase in the number of transport units, which increases the environmental burden on the environment. The rock mass extracted from the quarry is stored in external dumps, which occupy large areas and significantly worsen the ecology of the region. The operation of mining equipment on dumps with existing technologies causes a number of problems, the main of which is the movement of equipment near the prism of a possible rock collapse. It is proposed to use container technology for transporting the laying rocks in the dump, where the main element of the technology is a mobile lifting machine, which eliminates the need to build roads or railways on board and on the surface of the dump. Self-unloading of container equipment allows you to pour the rock mass directly to the place of laying on the dump. Containers with rock are installed in front of the front of the dump, and the lifting machine is placed on a special platform of the dump. The rock mass is delivered from the faces by dump trucks of any load capacity and unloaded into the hopper of a plate feeder, which fills the containers as they are fed by a quarry lifting machine. the rock is laid in horizontal layers within the step of moving the lifting machine. The weighted average height of the rock rise is equal to half the height of the dump tier. With the new technology, the entire amount of work will be performed by one lifting machine. Increasing the height of the dump to 80 meters with a new method of dumping, reduce the area occupied by dumps by 175 thousand m2 per year. The use of container technology in the formation of the dump allows, when unloading rock from containers into the dump, to reduce energy consumption during the formation of the dump, and increase the economically advantageous height of the dump. This reduces the area occupied by dumps and reduces the harmful effects of mining on the environment. The article discusses the technology of dumping during the formation of dumps using bulldozers in the conditions of Northern Kazakhstan. Traditional technology involves the involvement of a complex of equipment consisting of 8 dump trucks and 1 bulldozer. According to the new technology, the same amount of work can be done thanks to 1 lifting machine. Based on the calculations carried out, it was found that the intensity of dust emissions from internal sources decreases by 1,576 tons per year. A decrease in dust emissions is also observed with an increase in the height of the dump due to a decrease in area, while the difference was 75.57 tons per year. The total decrease from container technology is 1,651.57 tons per year.

Heel riser height influence on kinematics and muscle activity of ski mountaineering – A field based study

Introduction The ski binding plays an important role in ski mountaineering. When traveling uphill, the binding has an adjustable heel height known as the riser. Previous laboratory research reported joint kinematics and kinetics are influenced by riser height, however little is known about changes to muscle activity associated with differing joint motion. The purpose of this work was to assess riser height influence on kinematics and muscle activity at different slopes during on-snow skiing. Methods Three female and nine male recreational ski mountaineers (19-26 y) were tested on 5o and 16o gradients using no riser (0 cm) and riser (5.3 cm) at a submaximal 80% HRmax. Each subject used Backland 85 UL skis and Backland Bindings (Atomic Skis, Altenmarkt, Austria). Subjects skied for 6 min at each binding setting with the last 10 gait-cycles evaluating lower limb joint motion gathered from 2D-sagittal plane motion capture. Electromyography (EMG) collected unilaterally on the rectus femoris, biceps femoris, medial gastrocnemius and triceps brachii also. Results 5o slope: hip range of motion (ROM) decreased (p = .003), ankle ROM decreased (p = .005), stride length decreased (p = .004), rating of perceived exertion (RPE) increased (p = .02) for riser compared to no riser. At 16o slope: hip ROM decreased (p = .001), and RPE decreased (p = .004) for riser compared to no riser. HR, glide distance, velocity, EMG, and net mechanical efficiency were not different between riser heights on either slope. Discussion/Conclusion Lower body joint kinematics, step length and RPE varied significantly with riser height. Kinematic differences did not impact velocity or muscle activity when controlling pace. These results agree with previous findings showing minimal differences in EMG and HR while lower body kinematics and RPE changed with riser height.

Super absorbent polymer (SAP) on water‐salt transport in saline alkali soil: Effects of dosage, height and thickness

AbstractSoil salinisation is a pervasive form of land degradation posing a significant threat to the global environment. Saline soil, covering roughly 10% of the total land area, represents a crucial reserve of land resources. The use of super absorbent polymer (SAP) impacts capillary water movement through the soil because of its exceptional water absorption and retention capabilities. SAP is expected to influence the intricate water‐salt migration processes and their redistribution within soil. This study employed soil column experiments to investigate the impacts of varying SAP dosages (A), heights (B) and thicknesses (C) on soil water and salt transport in the Tianjin Binhai New Area, China. The main findings showed that: (1) average capillary water rise rate decreased with SAP dosage increase. The groundwater recharge trend in time was like that of capillary water rise height; (2) SAP usage increased water and salt content on the application layer and reduced surface soil salt accumulation; (3) the best SAP combination for application was 1.1% SAP at 17–18 cm from the groundwater level. This study provides basic effective SAP application strategies for preventing soil salinisation.

Short-term outcomes of all-inside endoscopic running locked stitch technique for acute achilles tendon ruptures

Objective: To evaluate the short-term outcomes of all-inside endoscopic running locked stitch technique for acute Achilles tendon ruptures. Methods: This is a retrospective case series study. Forty cases with acute Achilles tendon rupture were treated with the all-inside endoscopic running locked stitch technique from April 2020 to March 2022. There were 44 males and 4 females, aged (34.8±7.4) years (range: 24 to 50 years). Body mass index was (21.2±2.4)kg/m2 (range: 18 to 26 kg/m2); There were 29 cases (60.4%) on the left side and 19 cases (39.6%) on the right side. Under endoscopic control, the proximal tendon stumps were stitched with the running locked method using a semi-automatic flexible suture passer. The threads of the high-strength suture were grasped through the paratenon sub-space and then fixed into calcaneal insertion with a knotless anchor. MRI of Achilles tendon, surgical time and complications were assessed. Achilles tendon total rupture score (ATRS), Achilles tendon resting angle, and heel rise height scale were utilized to evaluate final clinical outcomes. The differences of bilateral limbs were compared using the paired t test. Results: The follow-up time was (24.1±3.5)months (range:18 to 32 months). Appropriate tendon regeneration was observed on MRI at post-operative 12 months. The median ATRS score (M(IQR)) was 95.0 (4.7) points. Furthermore, there was no significant difference between the injured and contralateral side in the Achilles tendon resting angle ((17.1±2.4)° vs. (17.4±2.6)°, t=1.92,P=0.062) and heel rise height ((14.2±1.7)cm vs. (14.4±1.5)cm, t=1.71,P=0.094). No nerve injuries, infection, deep vein thrombosis and re-ruptures were encountered. Sports activity resumed six months postoperative in 46 patients. One patient had a slight anchor cut-out, due to an addition injury, which was removed after 5 months. Conclusions: All-inside endoscopic running locked stitch technique for acute Achilles tendon ruptures shows promising results. It provides stable connection of the tendon stumps with a low risk of complications.

Fracture mechanical properties of sandstone with pre-fabricated cracks under freeze–thaw cycles

This paper evaluates the effect of freeze–thaw (F-T) cycles on the fracture mechanical properties of rocks with pre-fabricated cracks through experimental and numerical simulation. Three-point bending tests are conducted to determine the fracture characteristics of cyan sandstone with varying pre-fabricated crack heights. Subsequently, the failure characteristics of cyan sandstone with pre-fabricated cracks under F-T cycles are examined. A numerical model using parallel bond modeling (PBM) is established and validated against experimental results to further investigate the fracture behavior of sandstones with pre-fabricated cracks. Results demonstrate that both axial peak force and fracture toughness (KIC) linearly decrease with increasing freeze–thaw (F-T) cycles, and the axial peak force reduces with the rise in pre-fabricated crack height (Hc). The deformation damage process is categorized into four stages: compression-density, elastic deformation, pre-peak destabilization, and post-peak destabilization damage. Energy evolution is closely tied to microcrack initiation and propagation, with the majority of energy dissipating as microcrack surface energy. Both strain energy and dissipation energy decrease linearly with increased F-T cycles. These findings offer valuable insights for investigating the fracture mechanism of fractured rock mass in cold regions.

Thermo-fluidic behavior and entropy interpretation of ternary hybrid nanofluid inside an inclined domain having semi-circular heater and triangle-shaped corrugated walls

The present work deals with thermal aspect and entropy of ternary hybrid nanofluid (Graphene, Al2O3, and MWCNT as nanoparticles and water as base fluid) inside an inclined domain considering heat generation/absorption. The domain possesses triangle-shaped corrugated walls with variable height and a semi-circular heater located on its bottom wall. Finite element method (FEM) is employed to acquire a well-defined solution of the non-dimensional governing equations along with the boundary conditions. The influence of the pertinent parameters along with their ranges (0.2≤b≤0.3), (105≤Ra≤106), (0o≤η≤90o), (−1≤Hs≤1) has been studied. Some striking outcomes of the present investigation are that streamlines and entropy generation (EnT) peter out while local Nusselt number (Nuloc) and average Bejan number (Beave) ameliorate with rise in dimensionless height of the corrugated wall (b). The absolute maximum values of vertical and horizontal velocities of ternary hybrid nanofluid enhance by 96.47 % and 29.5 %, respectively, when inclination angle (η) increases from 45o to 90o. It is visualized that Nusselt number is maximum subject to heat sink while it attains a minimum value in response to heat source. Because of triangle shaped corrugated walls and ternary hybrid nanofluid, the present problem contributes superior cooling in thermal systems featured with such complex geometry in industries.

Study on effect of melt level on heat transfer characteristics and quality of continuously cast Al-Mg2Si composite sheet

Composite sheets fabricated by the Twin roll casting (TRC) process often suffer from quality issues, primarily microporosity resulting from solidification shrinkage. The presence of fabrication defects can be controlled by varying the casting parameters such as casting speed, superheat temperature, rolling force, and the height of the liquid metal in the melt pool. The present study developed a three-dimensional model to analyze the solidification and flow behavior of the melt with increasing melt pool height (4 cm, 6 cm, 8 cm) to see the quality of the fabricated Al-Mg2Si composite sheet. The developed model was validated using the optimized inlet temperature and interlamellar spacing. This model studies the effect of melt pool height on the solidification behavior, optimized inlet temperature, temperature gradient and heat flux. Results show that the increasing melt pool height shifts a solidification temperature above the roll exit and requires a higher inlet temperature for continuous sheet fabrication. Increased melt pool height decreases the heat flux from the roller surface and shows a lesser velocity fluctuation at the top and bottom of the melt pool. Experimental investigation demonstrates that a rise in melt pool height lowers the porosity in the casted sheet from 10.9% to 2.7% due to improved temperature gradient and pressure at the roller exit, enhancing sheet quality within the TRC process.

All-inside endoscopic semiautomatic running locked stitch technique shows favourable outcomes for acute Achilles tendon ruptures.

The safety and reliability of endoscopic Achilles tendon rupture repair are still concerning aspects. This study's aim is to evaluate an all-inside endoscopic semiautomatic running locked stitch (Endo-SARLS) technique. Forty cases with acute Achilles tendon rupture were treated with the all-inside Endo-SARLS technique between 2020 and 2021. Under endoscopic control, the proximal tendon stumps were stitched with the running locked method using a semiautomatic flexible suture passer. The threads of the high-strength suture were grasped through the paratenon subspace and then fixed into calcaneal insertion with a knotless anchor. Magnetic resonance imaging (MRI), surgical timeand complications were assessed. Achilles Tendon Total Rupture Score (ATRS), Achilles Tendon Resting Angle (ATRA)and Heel Rise Height Scale (HRHS) were utilised to evaluate final outcomes. The average follow-up time was 25.4 ± 0.4 (range: 24-32) months. Appropriate tendon regeneration was observed on MRI after 12 months. At the final follow-up, the median value of ATRS score was 95 (interquartile range: 94, 98). Furthermore, there is no significant difference between the injured and contralateral side in the average ATRA (18.2 ± 1.8 vs. 18.3 ± 1.9°, ns) and median value of HRHS [14.5 (13.3, 15.5) vs. 14.8 (13.5, 15.6) cm, ns]. No infection and nerve injuries were encountered. Thirty-ninepatients reported that they resumed casual sports activity after 6 months. One patient had a slight anchor cut-out, due to an addition injury, which was removed after 5 months. An all-inside Endo-SARLS technique showed promising clinical results for acute Achilles tendon ruptures. This procedure reduces the risk of sural nerve injuries while establishing a reliable connection between the tendon stumps. Level IV.

Construction and characteristic analysis of background error covariance coupled with land surface temperature

Land surface temperature (LST) is the key variable in land–atmosphere interaction, having an important impact on weather and climate forecasting. However, achieving consistent analysis of LST and the atmosphere in assimilation is quite challenging. This is because there is limited knowledge about the cross-component background error covariance (BEC) between LST and atmospheric state variables. This study aims to clarify whether there is a relationship between the error of LST and atmospheric variables, and whether this relationship varies spatially and temporally. To this end, the BEC coupled with atmospheric variables and LST was constructed (LST-BEC), and its characteristics were analyzed based on the 2023 mei-yu season. The general characteristics of LST-BEC show that the LST is mainly correlated with the atmospheric temperature and the correlation decreases gradually with a rise in atmospheric height, and the error standard deviation of the LST is noticeably larger than that of the low-level atmospheric temperature. The spatiotemporal characteristics of LST-BEC on the heavy-rain day and light-rain day show that the error correlation and error standard deviation of LST and low-level atmospheric temperature and humidity are closely related to the weather background, and also have obvious diurnal variations. These results provide valuable information for strongly coupled land–atmosphere assimilation.摘要地表温度 (LST) 是涉及陆气相互作用的关键变量, 对天气气候预报具有重要影响. 不过在同化中实现LST与大气的协调分析却并不容易. 这是因为目前对跨陆气圈层的背景误差协方差 (BEC) 的了解较少. 本文旨在探究LST与大气的背景误差是否存在联系, 以及这种联系是否存在时空变化. 为此, 本研究构建了耦合大气变量和LST的BEC, 并基于2023年梅雨季分析了其特征. 总体特征表明: LST误差主要与大气温度相关; 随着大气高度的上升, 误差相关性逐渐减小; LST误差的标准差明显大于低层大气温度. “多雨日”和“少雨日”的时空特征表明, LST与低层大气温湿度误差的相关性及标准差均与天气背景密切相关, 且具有明显的昼夜变化. 上述结果可为后续陆气强耦合同化提供参考.

Научно-технологические основы разработки месторождений подземных вод с принудительным самоизливом

Introduction. A two-well borehole system is proposed, providing for the extraction of groundwater by forced self-discharge. The essence is to create conditions for the emergence of a down hole energy source in the form of hydraulic shocks, alternating hydraulic impulses affecting aquifers and ensuring the rise of water to a height. Materials and methods of research. A block diagram of a two-well circulation system of wells consisting of an above-ground tank, an injection well with a ledge, a water-lifting well connected by an intermediate trunk. The objects of the study are the shape of the above–ground tank, its connection with the injection well, the location of the ledge and the conditions for conducting a water circulation channel from the ledge to the above-ground tank. Methods – calculation of the energy characteristics of a two-well system, experiments to study the mechanism of the origin of incomplete hydraulic shock, boundary values of the modes of water movement in the system and the coefficient of injection of rocks. They were carried out on the installation with the possibility of visual observation of the processes taking place in the system. Results. When an incomplete hydraulic shock occurs on the ledge of the injection well, the flow is divided into core and lateral components. The water flow from the tank into the well was in the range of 20–60 l/min. The origin of incomplete hydraulic shock occurred at a water flow rate of 20 l/min, with an increase in pressure up to 7.0 atmospheres. The boundary values of the laminar flow mode of water flow are 60 l/min. The height of the water rise (H) mainly depends on the depth of origin of incomplete hydraulic shock (H1). The ejection coefficient of rocks decreases with increasing flow rate of the working flow. Discussion. The results of the study are due to the design features of the elements of the two-well circulation system of wells. The operating conditions of the system are the type of communication ground tank – injection well – aquifer, the location of the ledge, the execution of the water circulation channel from the ledge to the entrance to the ground tank with one diameter, the preservation of the laminar flow regime of water, the exclusion of pressure loss and water leakage in the intermediate trunk. Conclusions. The conditions for the origin of a down hole energy source in the form of renewable hydraulic shocks, which have a hydro impulsive effect on aquifers, have been established. A block diagram of the injection and circulation system of wells for the extraction of groundwater by forced self-discharge has been formed. Resume. The validity of the idea of injection-forced self-discharge of groundwater is proved by the results of research. The results are applicable in the development of groundwater with low-pressure and non-pressure aquifers. The objects of future research are the optimal ratios of the diameter of the injection well and the passage section of the ledge, the expansion of the boundary values of the flow transition from laminar to turbulent motion, and an increase in the ejection coefficient.

Mapping the Vertical Gas Structure of the Planet-hosting PDS 70 Disk

PDS 70 hosts two massive, still-accreting planets and the inclined orientation of its protoplanetary disk presents a unique opportunity to directly probe the vertical gas structure of a planet-hosting disk. Here, we use high-spatial-resolution (≈0.″1; 10 au) observations in a set of CO isotopologue lines and HCO+ J = 4−3 to map the full 2D (r, z) disk structure from the disk atmosphere, as traced by 12CO, to closer to the midplane, as probed by less abundant isotopologues and HCO+. In the PDS 70 disk, 12CO traces a height of z/r ≈ 0.3, 13CO is found at z/r ≈ 0.1, and C18O originates at, or near, the midplane. The HCO+ surface arises from z/r ≈ 0.2 and is one of the few non-CO emission surfaces constrained with high-fidelity in disks to date. In the 12CO J = 3−2 line, we resolve a vertical dip and steep rise in height at the cavity wall, making PDS 70 the first transition disk where this effect is directly seen in line-emitting heights. In the outer disk, the CO emission heights of PDS 70 appear typical for its stellar mass and disk size and are not substantially altered by the two inner embedded planets. By combining CO isotopologue and HCO+ lines, we derive the 2D gas temperature structure and estimate a midplane CO snowline of ≈ 56–85 au. This implies that both PDS 70b and 70c are located interior to the CO snowline and are likely accreting gas with a high C/O ratio of ≈ 1.0, which provides context for future planetary atmospheric measurements from, e.g., JWST, and for properly modeling their formation histories.

Electroosmosis and electrophoresis in soft clay under direct current electric field

The demand for innovative and cost-effective in-situ consolidation technologies in soft clay stimulated the effort to employ electrokinetic phenomena in soils under an electric field. This work explains the principles of electrophoresis and electroosmosis in soft clay under an electric field and discusses the implacations of these results for field implementation of the technique. The experimental work reported here was carried out to shed light on the principles by considering various influencing factors. The results show that there is a threshold current (about 15 mA) for electroosmosis and electrophoresis in soft clay. Below the threshold current, electrophoresis plays a major role and is accompanied by weak electroosmosis. The particle size, dry density, and boundary rise height of electrophoretic soil in anode chamber are mainly affected by soil moisture content, electrode in electrolyte length, and bottom of electrode to soil surface distance. The closer the soil moisture content is to the average value of the liquid limit and plastic limit, the denser the electrophoretic soil will be. Above the threshold current, almost only electroosmosis occurs. The greater the current, the greater the electroosmosis. In practical engineering application, electrodes are usually directly inserted into the soft clay. This results in the current usually being much greater than the threshold current, meaning the electrophoretic phenomenon in the soil can be negligible.

CO2 capture and hydrogen generation from a solar-assisted and integrated fluid catalytic cracking process: Energy, exergy, and economic analysis

The fluid catalytic cracking (FCC) process transforms heavy wastes into lighter, more valuable (naphtha, light olefins and gases) products. However, the unit's byproducts contain a large quantity of CO2, which contributes to global warming. As a result, the purpose of this research was to increase the production of valuable products such as light olefins, naphtha, and hydrogen while reducing environmental impacts using the water gas shift reaction, with sensitivity analysis for three parameters (riser height, FCC feed temperature, and inlet naphtha mass flow). As a result of increasing the riser height, the output of light olefins (45%) and gases (32%) increased. Furthermore, the amount of hydrogen produced increases with a decrease in riser height (about 6%) and an increase in inlet naphtha mass flow (about 8%). Energy and exergy assessments were also carried out. It was determined that FCC had the lowest exergy destruction with a contribution of 23 MW when compared to its energy usage of 172 MW. The cooler, on the other hand, was one of the process's most energy-consuming (25%) and damaging (26%). As a result, this technique can lessen environmental effects by absorbing 125 tons of CO2 every hour and producing 3484 kg/h of hydrogen. Economic evaluations were also undertaken, and the results revealed that the cooler has the lowest exergoeconomic factor (1%) while the FCC unit contributes the most (95%). The fractionator column is also the most expensive device in the whole process.

O3 sensitivity and vertical distribution of summertime HCHO, NO2, and SO2 in Shihezi, China

Shihezi City has experienced severe ozone pollution. The vertical observation of ozone precursors (NO2 and HCHO) and SO2 in this area was conducted by multi-axis differential optical absorption spectroscopy in summer, 2023. During this experiment, ozone was measured at an average concentration of 94.89 ± 37.46 μg/m3, and it mainly increased when the northerly wind dominated, accompanied by the increasing of its precursors. In addition, SO2 had a relatively high concentration and elevated with the rising ozone concentration, remarkably different from other cities in China. The average vertical distribution of HCHO in the ozone pollution period was a Gaussian type, with the peak value at about 0.2 km. In contrast, the vertical distribution of NO2 and SO2 decreased exponentially with the rise of vertical height, and their concentrations dropped rapidly within 0–1 km. The RFN range of the transitional regime in Shihezi City was [1.26, 2.80]. Given that ozone pollution mostly occurred when RFN was 1–2, the chemical production of near-surface ozone in Shihezi City was controlled by a transition regime. The RFN vertical pattern was Gaussian type and reached a maximal value at 400–600 m. RFN increased at the middle altitude (0.4–1.2 km), and the ozone formation was controlled by the transitional regime. RFN decreased above 1.2 km, and the photochemical ozone formation was mainly controlled by a VOCs-limited regime. This study provides an improved understanding of O3 precursors vertical distribution and O3 formation sensitivity in Shihezi City.

Future changes in intense tropical cyclone hazards in the Pearl River Delta region: an air-wave-ocean coupled model study

The Pearl River Delta (PRD) region is highly vulnerable to tropical cyclone (TC)-caused coastal hazards due to its long and meandering shoreline and well-developed economy. With global warming expected to continue or worsen in the rest of the twenty-first century, this study examines the TC impact on the PRD coastal regions by reproducing three intense landfalling TCs, namely Vicente (2012), Hato (2017), Mangkhut (2018), using a sophisticated air-wave-ocean coupled model of high spatial resolution (1-km atmosphere and 500-m wave and ocean). The simulations are conducted using present-day reanalysis data and the same TCs occurring in a pseudo-global warming scenario projected for the 2090s. Results indicate that the coupled model accurately reproduces the air-wave-ocean status during the TC episodes. The 2090s thermodynamic status effectively increases the intensity of intense TCs, leading to more severe coastal hazards including gale, rainstorm, and storm surges and waves. On average, the maximum surface wind speed within 50–200 km to the right of the TC center can increase by 4.3 m/s (+22%). The 99th and the 99.9th percentile of accumulated rainfall will increase from 405 to 475 mm (+17.3%), and from 619 to 735 mm (+18.6%), respectively. The maximum significant wave height at the ocean is lifted by an average of 57 cm (+13.8%), and the coastline typically faces a 40–80 cm increase. The maximum storm surges are lifted by 30–80 cm over the open sea but aggravate much higher along the coastline, especially for narrowing estuaries. For Typhoon Vicente (2012), there is more than a 200 cm wave height increase observed both at open sea and along the coastline. In the 2090s context, a combination of mean sea level rise, storm surge, and wave height can reach more than 300 cm increase in total water level at certain hot-spot coastlines, without considering the superposition of spring tides.

Effects of riser height and pipeline length on the transition boundary and frequency of severe slugging in offshore pipelines

Investigating the transition boundary and frequency characteristics of severe slugging under different riser heights and pipeline lengths provides important support for the expansion of offshore oil and gas to deeper waters. The visualization research on air-water two-phase flow is carried out in a system with a horizontal pipeline length of 1687 m and riser heights of 16 m, 22 m, and 29 m, and flow pattern maps are plotted. Based on existing experimental data, the database of the flow pattern and slugging frequency in pipeline-riser systems with riser heights of 3–29 m, pipeline lengths of 10–1687 m, and pipe diameters of 25.4–50.8 mm is established. The long pipeline makes the gas pressure growth rate slower than that of the liquid pressure in the riser, which causes severe slugging occurring at higher superficial gas velocity. On the contrary, increasing the riser height causes the boundary of severe slugging to shift to a lower superficial gas velocity. The severe slugging length is greater in the higher riser and longer pipeline system, causing a smaller severe slugging frequency. A correlation for predicting severe slugging frequency at various riser heights, pipe lengths, and pipe diameters is established by employing gas and liquid Froude numbers.