Maximum Ratio Research Articles

Drought mitigation operation of water conservancy projects under severe droughts

ABSTRACT Severe droughts typically last for extended periods and result in substantial water shortages, posing challenges for water conservancy projects. This study proposed a framework for coordinating drought mitigation operations across projects of various scales. First, the regulation and drought mitigation capacities of each project were analyzed, and thus critical reservoirs was identified. Subsequently, a joint regulation model for water supply, prioritizing projects based on their regulatory capacity from weak to strong, was established. An optimization model is then developed to determine the drought-limited levels for critical reservoirs, aiming to minimize water shortages. This model facilitates temporal coordination of water resources to prevent severe water shortages with frequent mild water shortages. Results in the Chuxionglucheng District of Chuxiong, Yunnan Province, during the severe drought period from 2009 to 2013 demonstrate significant reductions in water shortage. Specifically, the maximum shortage ratio decreased from 59 to 45% for agriculture and from 52 to 8% for industry. Moreover, emergency measures for drought mitigation were compared and recommended for regions with weak projects regulation. Overall, this framework offers a systematic approach to enhancing drought resilience across diverse water conservancy projects in severe drought conditions.

Study on seismic performance of SRC frame-bent structures in CAP1400 nuclear power plants

With the conventional island turbine plant project of a CAP1400 nuclear power plant (NPP) as the research background, this paper proposed to apply steel reinforced concrete (SRC) frame-bent structure system to the main building of the NPP. Substructures comprising three frames and two spans from the prototype structure were identified for testing, and a test model was constructed at a scale ratio of 1/7 to test the dynamic and pseudo-dynamic characteristics of the substructures. On the basis of the test results, the structure was further verified using the finite element analysis method. The results showed that the first three modes of substructure were respectively lateral translation with torsion, longitudinal translation with torsion and torsion; The ratio between the third-order and first-order mode cycles was 0.72, indicating that the torsional stiffness of the structure was relatively small and the torsional effect was obvious. When the maximum acceleration peak was 2200 gal, the maximum inter-story drift ratio of the model structure reached 1/31. Ultimately, when the structure was finally destroyed, the concrete at the bottom of each SRC column was crushed and peeled off.

Investigation of mixing and heat transfer characteristics of long-hole SK direct contact heat exchanger

In this study, in order to improve the efficiency of direct contact heat exchanger (DCHE), SK static mixers with different perforation index (PI) were applied. Numerical simulation (volume of fluid model) were used to investigate the performance of the static mixer, which shape was designed as long-holes, under fixed aspect and helical ratios. The feasibility and accuracy of numerical simulation results were verified by self-established direct contact heat transfer (DCHT) experimental platform. Under six different PI values (0 %, 10 %, 18 %, 26 %, 32 %, and 38 %), the heat transfer performance of DCHE was evaluated by applying two heat transfer mediums (THERMINOL62 and R141b). The results indicated that the gaseous working medium outlet temperature, turbulence intensity, turbulence kinetic energy, and volumetric heat transfer coefficient (VHTC) of the system showed an increasing trend as PI increased from 0 % to 32 %, then a decreasing trend can be observed from 32 % to 38 %. The maximum turbulence intensity and turbulence kinetic energy of 17.56 % and 0.015 m2/s2 can be found in PI = 32 %, as well as a maximum enhancement ratio of 49 % in VHTC compared to PI = 0 % can be achieved. In addition, only a small pressure drop increase is observed in PI = 32 % compared to PI = 0 %.

Bat thermoregulation in the heat: seasonal variation in evaporative cooling capacities in four species of European bats

Phenotypic flexibility is an important source of physiological variation in endotherms and plays an integral role in species’ response to rapid environmental changes. Studies of phenotypic flexibility have focused on winter acclimatization and cold endurance, and there are fewer data on summer acclimatization and adjustments in heat dissipation capacity, especially in Temperate-Zone species. We used indirect calorimetry and thermometry to test if thermoregulation at high air temperatures (Ta) varies between spring and summer in four species of European vespertilionid bats: Nyctalus noctula, Pipistrellus nathusii, P. pygmaeus, and P. pipistrellus. We measured subcutaneous body temperature (Tsub), evaporative water loss, and resting metabolic rate while exposing bats to a stepped profile of increasing Ta, from 28 °C–48 °C. We predicted that during summer, bats increase heat tolerance and evaporative cooling capacity, to better tolerate hotter Tas. In contrast, we found lower maximum ratios of evaporative heat loss (EHL) to metabolic heat production (MHP) during summer, but no seasonal differences in maximum Ta tolerated or Tsub. The main cause of this seasonal difference in maximum EHL/MHP seems to be from bats increasing EWL more gradually with increasing Ta in summer than spring, particularly in the smaller Pipistrellus species. Therefore, this seasonal variation in heat-dissipation strategies may reflect enhanced water conservation during summer to avoid dehydration, as bats are confined to roosts for longer and hotter days compared to spring.

Characteristics of a hybrid radio frequency capacitively and inductively coupled plasma using hydrogen gas

A hybrid combination of a radio frequency (RF) capacitively coupled plasma (CCP) equipped with a ring-shaped hollow powered electrode and an inductively coupled plasma (ICP) with a helical antenna is investigated in hydrogen gas. Characteristics of the RF hybrid plasma are measured by a Langmuir probe at a fixed position in the center between the RF powered and grounded electrode for various CCP powers of 50–150 W. The voltage drop across the CCP is found to be almost independent of the ICP power. The RF hybrid plasma attains a high ion density of the order of 1010 cm−3 between the electrodes even at a low CCP input power of 50 W. The plasma density is strongly affected by the CCP generator power, while the floating potential is controlled by the ICP power, whereas the electron temperature is independent of the ICP power for various CCP powers. The negative ion production is enhanced by increasing the ICP power, resulting in a decrease in the ratio of the negative to the positive charge saturation current detected by the Langmuir probe. The maximum ratio of the negative ion density to the electron density is approximately 8 at a CCP power of 50 W and an ICP power of 250 W.

A Design of Economically Feasible Hybrid Energy System with Renewable Energy Ratio Priority

The reduction of fossil fuels which produce CO2 emission that damage the environment, can be done by implementing renewable energy-based power generations, such as solar and wind. This research designs a hybrid energy system by optimizing the use of existing diesel generators through the integration of renewable energy sources, such as solar photovoltaic and micro wind turbine, and is equipped with an energy storage system. This research uses HOMER Pro software to determine the optimal capacity of hybrid system components, and to calculate the cost of energy (CoE). Furthermore, the hybrid system configuration is analyzed by applying several objectives. The objectives of the hybrid system design are to prioritize a maximum renewable energy penetration ratio within permitted annual capacity shortage and with the CoE lower than the existing CoE. The research results show that the proposed hybrid energy system can provide a renewable energy penetration ratio of 57.1% with CoE of IDR 3,510/kWh.

Skirt piles in foundation: a structural rehabilitation solution for fixed offshore platforms

An analysis and structural design of strength and ductility level earthquake is presented in this paper. Numerical results show that structural failure under seismic loads is sensitive to the degree of deterioration of structural steel. The structural elements do not present any excess stress, that is, all stress ratios are less than unity. The maximum stress ratio is 0.942, in the superstructure of element 1586-1571, which corresponds to a main deck beam elevation (+) 15,850 m.

Vibration characteristics of dual-rotor system with staggered-type double elastic ring squeeze film dampers under maneuvering flight

The vibration of the rotor system is significantly intensified during maneuvering flight, rendering traditional elastic ring squeeze film dampers (ERSFDs) insufficient or unstable. To improve the applicability of dampers, a novel structure of staggered-type double elastic ring squeeze film dampers (SDERSFD) is proposed in this paper. Through the synergistic effect of double elastic rings, the damping effect is significantly enhanced, and the circumferential stiffness anisotropy of the damper is improved, which is more suitable for vibration reduction requirements under complex working conditions. Utilizing the Reynolds equation, the internal and external pressure field control equations of the double elastic rings are established. The finite difference method is then employed to solve the dynamic characteristics of the damper. Additionally, a finite element model of the dual-rotor system with SDERSFDs considering complex dynamic factors such as unbalanced force, oil film force, gravity, and additional inertial force caused by maneuvering flight is established for the study of nonlinear rotor dynamic characteristics and the analysis of SDERSFDs vibration reduction effect. Based on the model, the influence of various factors such as maneuvering speed, maneuvering radius, rotor speed and unbalance on the transient response of dive-pull up condition is analyzed. The results reveal that during dive-pull up, the vibration of the rotor system intensifies significantly. When compared with the ERSFDs, the SDERSFDs effectively reduce the vibration amplitudes of the rotor system under maneuvering flight condition, achieving the maximum vibration reduction ratio of 48.9%. Furthermore, the SDERSFD exhibits robustness against large maneuvering loads, enhancing the stability of the rotor system under extreme conditions.

Association between metabolic score of visceral fat and carotid atherosclerosis in Chinese health screening population: a cross-sectional study

BackgroundThe metabolic score for visceral fat (METS-VF) quantifies the cumulative burden of visceral and intra-abdominal adipose tissues. However, the relationship between the METS-VF and carotid atherosclerosis (CAS) has not been extensively explored. Therefore, this study aimed to investigate the association between the METS-VF and CAS.MethodsThis cross-sectional study enrolled 7089 Chinese adults who underwent physical examinations at the Zhenhai Lianhua Hospital, Zhejiang, China, in 2020. Multivariable logistic regression analysis was used to explore the linear relationship between METS-VF and CAS. Generalised additive models (GAM) were employed to evaluate potential nonlinear associations. The inflection points of METS-VF were determined using segmented logistic regression analysis optimised for maximum likelihood ratios and recursive algorithms.ResultsMultivariable logistic regression analysis revealed a positive correlation between METS-VF and CAS (odds ratio [OR]: 1.824, 95% confidence interval [CI]: 1.753–1.899; P < 0.001). The GAM analysis confirmed a nonlinear association between them [effective degrees of freedom: 4.803, χ2: 876.7, P < 0.001], with an inflection point at a METS-VF of 8.09 (P < 0.001 for log-likelihood ratio test). Below this inflection point, METS-VF exhibited a significant positive association with CAS risk (OR: 1.874, 95% CI: 1.796–1.954; P < 0.001). Conversely, no significant association was observed when METS-VF ≥ 8.09 (OR: 0.998, 95% CI: 0.786–1.268; P = 0.989).ConclusionsMETS-VF and CAS demonstrated a positive non-linear correlation, with the curve indicating a saturation effect at METS-VF = 8.09.

Nonswellable Hydrogel Patch with Tissue-Mimetic Mechanical Characteristics Remodeling In Vivo Microenvironment for Effective Adhesion Prevention.

Postoperative adhesion is a common complication after abdominal surgery, but current clinical products have unsatisfactory therapeutic effects. Here, we present a hydrogel patch formed in a single step through dialysis. The exchange of DMSO into water facilitates hydrophobic aggregate in situ formation and the formation of hydrogen bonds within the hydrogel. Thanks to the optimized component ratio and precise structural design. The hydrogel patch has soft-tissue-like mechanical characteristics, including high strength, high toughness, low modulus similar to the abdominal wall, good fatigue resistance, and fast self-recovery properties. The nonswellable hydrogel patch retains over 80% of its original mechanical properties after 7 days of immersion in physiological saline, with a maximum swelling ratio of 5.6%. Moreover, the hydrophobic biomultifunctionality of benzyl isothiocyanate can self-assemble onto the hydrogel patch during the sol-gel transition process, enabling it to remodel the inflammatory microenvironment through synergistic antibacterial, antioxidant, and anti-inflammatory effects. The hydrogel patch prevents postsurgical adhesion in a rat sidewall defect-cecum abrasion model and outperforms the leading commercial Interceed. It holds promising potential for clinical translation, considering that FDA-approved raw materials (PVA and gelatin) form the backbone of this effective hydrogel patch.

Assessment of pulmonary function in COPD patients using dynamic digital radiography: A novel approach utilizing lung signal intensity changes during forced breathing

ObjectivesTo investigate the association of lung signal intensity changes during forced breathing using dynamic digital radiography (DDR) with pulmonary function and disease severity in patients with chronic obstructive pulmonary disease (COPD). MethodsThis retrospective study included 46 healthy subjects and 33 COPD patients who underwent posteroanterior chest DDR examination. We collected raw signal intensity and gray-scale image data. The lung contour was extracted on the gray-scale images using our previously developed automated lung field tracking system and calculated the average of signal intensity values within the extracted lung contour on gray-scale images. Lung signal intensity changes were quantified as SImax/SImin, representing the maximum ratio of the average signal intensity in the inspiratory phase to that in the expiratory phase. We investigated the correlation between SImax/SImin and pulmonary function parameters, and differences in SImax/SImin by disease severity. ResultsSImax/SImin showed the highest correlation with VC (rs = 0.54, P < 0.0001), followed by FEV1 (rs = 0.44, P < 0.0001), both of which are key indicators of COPD pathophysiology. In a multivariate linear regression analysis adjusted for confounding factors, SImax/SImin was significantly lower in the severe COPD group compared to the normal group (P = 0.0004) and mild COPD group (P=0.0022), suggesting its potential usefulness in assessing COPD severity. ConclusionThis study suggests that the signal intensity changes of lung fields during forced breathing using DDR reflect the pathophysiology of COPD and can be a useful index in assessing pulmonary function in COPD patients, potentially improving COPD diagnosis and management.

Application of a newly constructed NGS panel with 45 X-linked microhaplotypes demonstrates the unique value of X-MH for kinship testing and mixture analysis

X-linked microhaplotypes (X-MHs) have the potential to be a valuable supplementary tool in complex kinship identification or the resolution of DNA mixtures, because they bring together the distinctive genetic pattern of X chromosomal markers and the benefits of microhaplotypes (MHs). In this study, we used the 1000 Genome database to screen and select 63 X-MHs; 18 MHs were filtered out though a batch sequencing assessment of the DNA samples collected from 112 unrelated Chinese Han individuals. The resulting 45-plex panel performed well in comprehensive assessments including repeatability, sensitivity, species specificity, resistance to PCR inhibitors or degradation, mutation rate, and accuracy in detecting DNA mixture samples. The minimum amount of DNA template that can be tested with this panel is 0.5 ng. Additionally, the alleles of the minor contributor can be accurately detected when the mixture rate is larger than 1:9 in female-male mixture or 1:19 in male-male mixture. Then, we calculated population parameters on each MH based on the allele frequency data obtained from the sequence results of the aforementioned 112 unrelated samples. Combining these parameters on each MH, it can be calculated that TDPm, TDPf, CPET, CPEDFM, CPEDFF and CNCEP3 of the 45-plex system were 1–8.99×10−13, 1–1.62×10−19, 0.9999999995, 0.9999981, 0.9955, 0.9999971 and 0.99940, respectively, indicating that the panel is capable in personal identification and parentage testing. To reveal the unique advantage of X-MHs in the analyses of complex kinship and male DNA mixture, further assessments were made. For complex kinship identification, 22 types of individual pairs with different second-degree kinship were simulated and different types of likelihood ratios (LR) were calculated for each. The results revealed that the panel can achieve accuracy of approximately 70 %∼80 % when dividing each of the three types of second-degree kinships into three or four groups. Theoretically, such sub-division cannot be done by using independent autosomal markers. For male DNA mixture analysis without suspects, the maximum likelihood ratio strategy was derived and employed in the estimation of the number of male contributors (NOMC). Simulations were conducted to verify the efficacy of the 45-plex panel in the field and to compare it with autosomal markers by assuming the 45 MHs as autosomal ones. The results showed that X-MHs can achieve higher accuracy in the estimation of NOMC than autosomal ones when the mixed males were unrelated. The results highlighted the unique value of X-linked MHs in complex kinship and male mixture analyses.

Bending Fatigue Properties of Ultra-High Toughness Cementitious Composite (UHTCC).

Ultra-High Toughness Cementitious Composite (UHTCC) represents a composite material meticulously engineered on the foundation of micromechanical principles. The multi-crack cracking and strain-hardening characteristics of UHTCC enable it to be applied to orthotropic steel decks to control the crack width. Different from most studies which only focus on hybrid fiber or fatigue characteristics, this paper studies the influence of hybrid fiber content on static mechanical properties, flexural toughness, and flexural fatigue characteristics of UHTCC under different stress levels. The compressive and flexural strength, bending toughness, and fatigue damage of UHTCC under different fiber ratios were compared, and the fatigue properties of hybrid fiber UHTCC were verified. The results reveal that hybrid fiber exerts a more pronounced effect on toughness, augmenting the maximum folding ratio by 23.7%. Single-doped steel fiber UHTCC exhibits a characteristic strain-softening phenomenon attributable to inadequate fiber content, whereas the bending toughness index of hybrid fiber UHTCC surpasses that of SF1.5P0 by 18.6%. Under low-stress conditions, UHTCC demonstrates a nearly threefold increase in bending fatigue life with a mere 1% steel fiber content, while the influence of polyvinyl alcohol (PVA) fiber on fatigue life is more significant: with an increase of only 1/5 volume content, the fatigue life increased by 29.8%, reaching a maximum increase of 43.2% at 1/4 volume content. Furthermore, the fatigue damage accumulation curve of UHTCC follows a three-stage inverted S-shaped trajectory. The inclusion of PVA fiber facilitates early initiation of stable cracking during the fatigue failure process, thereby advancing the entire strain stability development stage and mitigating external load forces through the proliferation of micro-cracks. Consequently, compared to SF1P0, the ε0 of SF1P5 experiences a significant increase, reaching 143.43%.

Multi-file dynamic compression method based on classification algorithm in DNA storage.

The exponential growth in data volume has necessitated the adoption of alternative storage solutions, and DNA storage stands out as the most promising solution. However, the exorbitant costs associated with synthesis and sequencing impeded its development. Pre-compressing the data is recognized as one of the most effective approaches for reducing storage costs. However, different compression methods yield varying compression ratios for the same file, and compressing a large number of files with a single method may not achieve the maximum compression ratio. This study proposes a multi-file dynamic compression method based on machine learning classification algorithms that selects the appropriate compression method for each file to minimize the amount of data stored into DNA as much as possible. Firstly, four different compression methods are applied to the collected files. Subsequently, the optimal compression method is selected as a label, as well as the file type and size are used as features, which are put into seven machine learning classification algorithms for training. The results demonstrate that k-nearest neighbor outperforms other machine learning algorithms on the validation set and test set most of the time, achieving an accuracy rate of over 85% and showing less volatility. Additionally, the compression rate of 30.85% can be achieved according to k-nearest neighbor model, more than 4.5% compared to the traditional single compression method, resulting in significant cost savings for DNA storage in the range of $0.48 to 3 billion/TB. In comparison to the traditional compression method, the multi-file dynamic compression method demonstrates a more significant compression effect when compressing multiple files. Therefore, it can considerably decrease the cost of DNA storage and facilitate the widespread implementation of DNA storage technology.

Evaluation of energy performance and environmental benefits for transcritical CO2 thermal system in high-speed trains

The conventional air conditioning system used in high-speed railways has limitations in heating performance and environmental impact, necessitating the exploration of alternative refrigerants. The transcritical CO2 system has gained popularity due to its exceptional heating efficiency and environmental benefits. This study aims to evaluate the energy and environmental potentials for transcritical CO2 systems in high-speed trains based on four-vertical-and-four-horizontal railway lines within different climatic regions of China. A high-fidelity transcritical CO2 system model was first developed and validated through experiments. Then, a comprehensive energy and environmental evaluation method was proposed and applied to the four-vertical-and-four-horizontal railway lines. The results indicated that the transcritical CO2 system had a superior heating performance and competitive cooling performance based on daily and annual operations. Furthermore, the transcritical CO2 system exhibited significant environmental advantages with lower total life cycle climate performance for all lines, with an average emissions reduction ratio of 17.6% and a maximum emissions reduction ratio of 26.98%. These findings highlight the competitive energy performance and outstanding environmental benefits offered by transcritical CO2 systems as promising alternatives to air conditioning systems in railway transportation.

Association of Prenatal Exposure to Antiseizure Medications With Creative and Executive Function at Age 4.5 Years.

Neurodevelopmental effects of fetal antiseizure medication (ASM) exposure on creativity and executive functions are poorly understood. We previously found fetal valproate exposure to adversely affect measures of creativity and executive functions. In this study, we examine fetal exposure of newer ASMs on these functions in children of women with epilepsy (WWE) compared with children of healthy women (HW). The Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs study is a multicenter NIH-funded prospective observational cohort study of WWE and HW enrolled in pregnancy and their offsprings. This report examines blindly assessed creativity and executive functions in 4.5-year-old children of WWE vs HW. In addition, exposure-dependent ASM effects during the third trimester were examined in children of WWE, using a ratio of maximum observed ASM concentrations and ratio of defined daily dose (ratio DDD). For polytherapy, ratios were summed across ASMs. Linear regression models adjusted for multiple potential confounding factors were conducted for all analyses. The primary outcome for 4.5-year-old children was the Torrance Test of Creative Thinking-Figural Creativity Index. Secondary outcomes included the Global Executive Composite Score from the Behavior Rating Inventory of Executive Function-Preschool Version and subscales and other indexes of both measures. The primary analysis included 251 children of WWE and 73 of HW. No differences in creativity or executive function were found between children of WWE vs HW. No ASM exposure-dependent effects were found for the creativity measures, but exposure-dependent effects for executive function were present for ratio ASM concentration and ratio DDD. Our findings at 4.5 years show no differences in creative thinking between children of WWE vs HW (-3.2 [-9.0 to 2.7], p = 0.286) or associations with fetal exposure to ASMs (-2.6 [-11.0 to 5.7], p = 0.530). Secondary analyses revealed fetal exposure-dependent effects for executive function in children of WWE (7.0 [2.9-11.2], p = 0.001), which are most marked for levetiracetam (12.9 [4.2-21.6], p = 0.004). Our findings suggest that even for relatively safe ASMs, dosing needs to be adjusted to concentrations that prevent seizures, but balance risks to the fetus that high concentrations may pose. The study is registered at ClinicalTrials.gov as NCT01730170.

Characterization of hydrophobic epoxy soybean oil-based rigid plastic reinforced with nano SiO2 particles

The study involved the production of rigid plastics by crosslinking vanillin-hexanediamine (VH) with epoxidized soybean oil (ESO) through an open ring reaction, resulting in the formation of VHE resin. Various proportions of nano SiO2 particles were added to the VHE resin in order to produce hydrophobic rigid plastics derived from renewable sources. This study evaluated the impact of different mass ratios of nanoparticles to VHE resin (1:10, 1:5, 3:10) on the performance of the resulting plastics. FTIR and 13C NMR analysis have verified that VH has effectively undergone crosslinking with ESO, leading to the formation of VHE with a uniformly smooth surface that is free from pores and cracks. The introduction of nano SiO2 particles enhances the surface roughness and surface energy of the VHES plastics, resulting in hydrophobic properties, as evidenced by their high water contact angles. The addition of nano SiO2 particles improved the resistance of the VHES plastics to degradation caused by light, heat, and electricity. Nevertheless, the improvement is constrained to a maximum ratio of 1.5 (VHES2) and diminishes as the ratio of SiO2 particles increases (3:10). Furthermore, VHES2 samples demonstrated commendable biodegradability in addition to their previously mentioned exceptional properties. The study's findings suggest that vanillin and vegetable oil can be used to create biodegradable, hydrophobic plastic.

Modal ordered shape factors as radar feature set

AbstractThe characteristic polarisation states form a second layer feature set by reflecting shape attributes about that target, enabling better identification performance of the resonance signature. These shape factors reflect a structure's curvature extent, dihedral degree between corners, and the axial ratio between principal axes by determining two characteristic angles associated with the null polarisation state and a ratio of the optimum maximum and minimum received powers, respectively. However, the accuracy of the shape factors degrades with a poorly estimated resonance signature caused by noise, missing resonance due to occlusion or ambiguity in late time onset. Thus, the authors aim to reduce the effect of these problems using an ensemble average to filter noise and enhance the signal strength, properly selecting a modal order to ensure modal consistency of the signature and decay sum (DS) to select the late time onset properly to avoid missing resonance within the polarisation matrix. Finally, a paradigm of two jetfighters validated the factors' discriminative potential across an azimuth plane of low depression angle. The results showed that a DS around 0.4 improves the estimated factors over most resonance modes and azimuth directions. At most target aspects, the first‐order shape factors consistently predicted a dominant parallel wedge‐shaped structure, while the second‐order shape factors consistently predicted a trough‐shaped structure; finally, the third‐order factors revealed wedge‐shape attributes at forward look aspects but trough‐shaped attributes at backward look aspects.

Collaborative design method for multi-impeller turbomachinery based on variable sectional-area distribution

By establishing the characterization model of variable sectional area distributions, a cascade design method of torque converter based on variable sectional area distribution is proposed. Additionally, the corresponding collaborative design method for multi-impeller turbomachinery is proposed and further studied. The design cases of the impellers with different sectional area distributions are constructed through the response surface method, and the corresponding hydrodynamic characteristics are further compared and explored. However, the design of different impeller sectional area distributions for the optimal performance of the whole turbomachinery requires the collaborative design of each component’s distribution results rather than a simple combination of such optimal impeller’s area distribution result. Thus a collaborative design strategy is proposed, which can improve the pump’s capacity performance by 8.83%, the maximum torque ratio performance can also increased by 6.33%, which proves that such a collaborative design method is an effective optimization design approach to improve the performance of the torque converter without altering the overall dimension. The experimental results of the optimal prototype show that the torque ratio reaches 5.33% higher than the original value, which indicates that such a collaborative optimization method for multi-impeller turbomachinery is effective and reliable.

Mineral trapping of carbon dioxide: Rapid hydrothermal synthesis experiments and carbon sequestration potential of dawsonite

Dawsonite, as a natural CO2 tracing mineral, is intimately associated with CO2 injection and serves as a crucial mineral for geological carbon sequestration. The massive and stable presence of dawsonite in the geological background is a key consideration for CO2 mineralization capture and plays a significant role in identifying CO2 geological burial sites. To investigate the optimal conditions for the rapid synthesis of dawsonite using CO2, we conducted comparative experiments to examine the three primary influencing factors: temperature (100 °C, 120 °C, 140 °C, 160 °C, 180 °C, and 200 °C), pH (8.5, 9, 9.5, 10, and 10.5), and reaction time (6 and 12 h). Through scanning electron microscopy and X-ray diffraction analysis, the optimal conditions for dawsonite synthesis were determined. The experiments revealed that within the pH range of 8.5–10.5 and at temperatures of 100–180 °C, the dawsonite products obtained are consistently pure, which indicates that CO2 can be effectively mineralized and sequestered as dawsonite within these temperature and pH ranges. The synthesis yield increased and then decreased with increasing pH and temperature. At 200 °C, the crystallinity of dawsonite decreased and the content of pseudo-boehmite increased. This suggests that higher temperature conditions are not conducive to the mineralization and sequestration of CO2. Extending the reaction time did not have a significant promoting effect on the quality of the product. The maximum amount of dawsonite synthesis, good dispersion and homogeneity of crystals, and maximum ratio of mineralization of CO2 by dawsonite were achieved at a temperature of 140 °C and a pH of 9.5, indicating that these are the optimal conditions for the hydrothermal synthesis of dawsonite using CO2. Moreover, these are the optimal geological conditions for the mineralization sequestration of CO2 in the form of dawsonite.