Shrinkage Ratio Research Articles

Factors Influencing on the Aneurysm Sac Shrinkage after Endovascular Abdominal Aortic Aneurysm Repair by the Analysis of the Patients with the Aneurysm Sac Shrinkage and Expansion.

Objectives: The aneurysmal sac shrinkage has been reported as the strong predictor of favorable long-term outcome after endovascular aneurysm repair (EVAR). We evaluated the effects of perioperative and intraoperative factors on the aneurysm sac shrinkage. Methods: EVAR was performed for 296 patients during August 2009-December 2021. Nine patients with type Ia, Ib, or III; 69 patients with the sac diameter change less than 5 mm; and five patients with sac re-expansion after shrunk more than 5 mm were excluded. Thus, patients with sac shrinkage 5 mm or more (79 patients, shrinkage group) and with sac expansion 5 mm or more (18 patients) were included in this study. Antifibrinolytic therapy with tranexamic acid (TXA) 1500 mg/day for 6 months after EVAR was introduced in March 2013 and patent aortic side branches were coil embolized during EVAR since July 2015. Patients' background and patent aortic side branches at the end of EVAR were evaluated. Results: Univariate analysis for comparison between patients with sac shrinkage and sac expansion revealed that males (82.3% vs. 55.6%, p = 0.021), without antiplatelet therapy (40.5% vs. 66.7%, p = 0.044) and TXA (79.8% vs. 38.9%, p <0.001), were significantly associated with sac shrinkage. By multivariate analysis, the odds ratio of sac shrinkage was 11.7 for males, 0.1 for the patients on antiplatelet therapy, and 6.5 for the patient who received TXA. The patients with patent inferior mesenteric artery (IMA) were less in the shrinkage group (20.3% vs. 77.8%, p <0.001) and with two or less patent lumbar arteries (LAs) were more in the shrinkage group (82.3% vs. 33.3%, p < 0.001). The odd ratio of sac shrinkage was 7.8 for occluded IMA and 3.9 for two or less patent LAs. Conclusion: The possibility of sac shrinkage would be high for the patient with occluded IMA and two or less patent LA at the end of EVAR, and that patient received TXA after EVAR. (This is a translation of Jpn J Vasc Surg 2022; 31: 291-297.).

Nanodiamond embedded polyaniline/polyvinylidene fluoride nanocomposites as microfiltration membranes for removal of industrial pollution.

Membrane fouling remains a challenge to the membrane technology. Herein, we report the fabrication of composite membranes of polyaniline/polyvinylidene fluoride (PANI/PVDF) blended with nanodiamond (ND) with improved antifouling properties. The designed membranes were characterized by XRD, FTIR and SEM techniques. Characterization analysis revealed that addition of ND has maintained the structural integrity and porosity of composite membranes. The membrane permeation and antifouling performances were tested for hydrophilicity, porosity, pure water flux, shrinkage ratio, salt rejection of zinc acetate and copper acetate, and their fouling recovery ratio (FRR) measurements. A high solvent content ratio of 0.55 and a low shrinkage ratio of <12% due to enhanced hydrophilicity and porosity of the composite membrane with fouling-recovery of membranes to 88% were achieved. Separation of copper and zinc ions from aqueous solution was achieved. These findings imply that ND-based PANI/PVDF composite membranes can effectively serve as microfiltration membranes in industrial and municipal wastewater treatment.

Effects of intraocular lens anterior edge design on anterior capsule morphology changes following femtosecond laser-assisted capsulotomy

PurposeTo compare morphological changes in the anterior capsule of two intraocular lenses (IOLs) with different anterior edge designs 6 months after femtosecond laser-assisted capsulotomy surgery (FLACs).MethodsThis study included 168 eyes from168 patients undergoing FLACs. Group A included 74 eyes from 74 patients who had an Acrysof IQ Restor SN6AD3 IOL implantation with a flat anterior edge and Group B included 94 eyes of 94 patients with a TECNIS Multifocal ZMB00 IOL implantation and a "peak-like" anterior edge. All patients were followed up for 6 months. We assessed anterior capsule morphological changes including variation of anterior opening diameters and lens epithelial cell (LEC) proliferation in four directions, variation of anterior opening area, and the level of anterior capsule opacification (ACO).ResultsVariation of anterior opening diameters in 4 directions were significantly lower in Group B (P < 0.05). Obvious shrinkage ratio of anterior opening diameters and contraction of anterior opening area (P < 0.05) appeared in Group A. LEC proliferation was along the "peak" in Group B, while it spread to the edge of anterior capsule in Group A. ACO grades 6 months after operation in Groups A and B were as follows: grade I in 28.38% and 82.98% of eyes, grade II in 51.35% and 17.02% of eyes, and grade III in 20.27% and 0% of eyes, respectively.ConclusionsThese findings suggest that a "peak-like" IOL anterior edge design played an important role in maintaining the morphology of anterior capsule in the early postoperative stage.

Artificial neural network and kinetic modeling of capers during dehydration and rehydration processes

AbstractThis study aimed to investigate the drying kinetics of capers at different temperatures and to examine the morphological changes of capers during the drying and rehydration processes. Computer‐aided image processing and Artificial Neural Network models (ANN) were used to analyze the shrinkage and moisture ratio of capers (drying) and the expansion of capers (rehydration). Lewis, Page, Fick's law, and logarithmic models were investigated to describe the conventional drying kinetics of capers at 50, 60, and 70°C; the logarithmic model was shown to be the best describing model (r2: 0.9996, 0.9996 and 0.9981, respectively). Effective diffusivities varied between 1.91 × 10−10 and 2.62 × 10−10 m2/s for the temperature range. The activation energy was 14.572 kJ/mol. Image processing revealed that diameter reduction rates were 1 × 10−4 mm/s for 50 and 70°C and 7 × 10−5 mm/s for 60°C. ANN was applied using multilayer perceptron models with three layers (input: ANN1, hidden: ANN2, and output: ANN3) which were sufficiently valid for predicting the experimental parameters (r2: 0.9992, 0.9915, and 0.8484, respectively). All morphological properties were reduced with drying, and shrinkage of capers was increased proportionally with the moisture content. The Global Sensitivity Analysis recognized treatment time as the most influential parameter affecting the moisture ratio and the caper diameter changes.Practical applicationsOne of the major problems for humans has been to improve food preservation techniques for long‐term storage. The major scope of industry is the drying of fruits and/or vegetables to produce dried foods with high quality and a long shelf life. To the best of our knowledge, drying of capers regarding the drying kinetics, modeling and quality changes has not been published to date. In this study, goal was to better understand drying kinetics and geometric changes that occur to capers during the dehydration and rehydration processes at various drying temperatures. Quantitative information regarding geometrical changes to capers was supplied by the image processing of the acquired pictures, which enabled rapid monitoring of physical changes during dehydration and rehydration. The remarked kinetic model, ANN model, and Quantitative information regarding geometrical changes are valuable information for researchers studying on drying of food and large‐scale dryer designers.

Combined Heat and Mass Transfer Associated with Kinetics Models for Analyzing Convective Stepwise Drying of Carrot Cubes.

Stepwise drying is an effective technique that promotes energy saving without additional capital cost. The stepwise drying mode was investigated for energy consumption and dried product qualities using a coupled heat and mass transfer model associated with kinetics equations of volume shrinkage and degradation of β-carotene in carrot cubes. Simulations were performed using a finite element method with extension of a chemical species transport. Validation experiments were carried out under constant drying modes at 60 °C, 70 °C and 80 °C using a lab-scale convective hot air dryer. The verified models were subsequently employed to investigate the effects of two step-up drying modes (60 to 70 °C and 60 to -80 °C). The optimal drying condition was determined using the synthetic evaluation index (SI) with criteria of high specific moisture evaporation rate (SMER), low shrinkage ratio and β-carotene degradation. Simulated results showed comparable agreement with experimental data of moisture content, shrinkage ratio and β-carotene ratio. Step-up drying of 60 to 70 °C gave the highest SMER of 0.50 × 10-3 kg of water evaporated per kWh, while the operation at constant temperature of 80 °C gave the lowest value of 0.19 × 10-3 kg of water evaporated per kWh. Model-predicted results showed less shrinkage of carrot cubes, but higher degradation of β-carotene under step-up drying compared to single-stage drying under temperature of 60 °C. Based on the highest SI value (0.36), carrot cubes were optimally dried under step-up mode of 60 to 70 °C.

The Effect of Initial Water Content and Density on the Swelling-Shrinkage and Cracking Characteristics of Compacted Clay

The swelling-shrinkage and cracking characteristics of compacted clay under the coupling effect of initial conditions are rarely studied. The dry-wet cycle test of compacted clay with varying initial water contents and densities was performed in this study; the size and cracking conditions were investigated. The results showed that when the initial moisture content was 21% and the dry density was 1.65 g/cm3, the longitudinal expansion amount of the compacted clay was relatively small. However, it was rather large when the initial water content was 17% and 19%. Under the same dry density, the final vertical shrinkage ratio of the sample with a water content of 21% was the smallest, while that of the samples with a water content of 23% and 25% was rather big. Under the same water content, the final vertical shrinkage ratio decreased with the increase in dry density. After three wetting-drying cycles, compacted clay with a dry density of 1.65 g/cm3 and an optimal initial water content of 21% produced the fewest cracks and had the lowest cracking factor (CF) (only 7.58%). The compacted clay specimens with the dry densities of 1.55 g/cm3 and 1.60 g/cm3 had rather significant cracking at the same initial moisture content of 21%. The mercury intrusion porosimetry (MIP) test demonstrated that in the first two dry and wet cycles, the distribution of large pores decreased and that of tiny pores increased. After the third cycle, the distribution of small and medium pores decreased slightly. The results of this study will provide theoretical guidance for selecting cover soils in landfills.

Effect of gum Arabic and ethanol pretreatments on drying kinetics and quality attributes of dried carrot slices

Carrot is an important root vegetable to the food industry and consumers due to its nutritional and health benefits. Given the high moisture content and low shelf life of fresh carrots, preserving this highly demanded vegetable is vital. This current research modelled the drying kinetics and evaluated the quality of ultrasonic-assisted gum Arabic and ethanol pretreated and oven-dried carrot slices. Fresh carrots were processed into thin slices and immersed in 3% gum Arabic (GA), ethanol (99.9%), and distilled water (control), followed by ultrasonication (frequency: 50 Hz, power: 500 W, temperature: 25 °C) for 10 min and drying in a hot air oven at 50 °C. The loss of moisture from the carrots was periodically recorded, converted to moisture ratio before fitted to eleven semi-theoretical thin layer drying mathematical models. The effects of the pretreatments on the retention of bioactive compounds and carrots' physical and chemical properties were also evaluated. From the tested models, the Diffusion, Modified Henderson and Pabis, and Two-term models showed the best fitting (R2 = 0.9944–0.9985; RSME = 0.0103–0.0227) to the experimental data from 3% GA and ethanol pretreated carrots, while control samples followed the Aghbasho model (R2 = 0.9999; RMSE = 0.0033). Overall, the 3% GA pretreated carrot slices exhibited better colour (yellowness: 25.82–34.50; total colour differences: 8.12–13.06), water activity (0.37–0.44), total phenolic content (1.34–2.99 mg GAE/100 g DM), β-carotene (7.63–13.07 mg/100 g DM), and DPPH radical scavenging activity (5.67–8.02 mM AAE/100 g DM) than ethanol pretreated carrot slices and control samples. At the same time, 3 % GA pretreatment did not affect the drying rate of the carrot slices. The total soluble solids/titratable acidity ratio, rehydration capacity, and shrinkage ratio did not significantly (p > 0.05) vary among the treatments. The findings of this study can be used to develop an optimal drying protocol for pretreated carrot slices and to produce shelf-stable carrot products that can be used dried, rehydrated, or in combination with other products.

Role of Intramuscular Connective Tissue in Water Holding Capacity of Porcine Muscles

This study evaluated the influence of intramuscular connective tissue (IMCT) on structural shrinkage and water loss during cooking. Longissimus thoracis (LT), semimembranosus (SM) and semitendinosus (ST) muscles were cut and boiled for 30 min in boiling water, followed by detection of water holding capacity (WHC), tenderness, fiber volume shrinkage and protein denaturation. Compared with LT and SM, ST had the best WHC and lowest WBSF and area shrinkage ratio. The mobility of immobilized water (T22) was key to holding the water of meat. ST contained the highest content of total and heat-soluble collagen. On the contrary, ST showed the lowest content of cross-links and decorin, which indicate the IMCT strength of ST is weaker than the other two. The heat-soluble collagen is positively correlated to T22. The shrinkage of heat-insoluble IMCT on WHC and WBSF may partly depend on the structural strength changes of IMCT components rather than solely caused by quantitative changes of IMCT.

Moisture-Related Shrinkage Behavior of Wood at Macroscale and Cellular Level.

Due to wood moisture sensitivity, shrinkage cracks tend to present wooden structures. These failures are caused by moisture-related shrinkage behavior. In order to avoid it, it is necessary to have a better understanding of shrinkage behavior. In this respect, studying the dimension changes in wood at different scales is of utmost significance for a better understanding of the shrinkage properties. Herein, the shrinkage behavior of Masson pines (Pinus massoniana) wood was investigated at macroscopic and cellular levels during moisture loss via digital image correlation using VIC-3D and digital microscopic systems, respectively. According to the full-field strain maps, shrinkage strain near the external face was higher than that at the internal face, which increased susceptibility to cracking at the external face of lumber. Additionally, the anisotropic shrinkage of wood was explored. The shrinkage ratio at the end of drying was about 5.5% in the tangential (T) direction and 3.5% in the radial (R) direction. However, at a cellular level, the shrinkage ratios in the T and R directions of earlywood tracheids were 7.13% and 2.46%, whereas the corresponding values for latewood tracheid were 9.27% and 5.52%, respectively. Furthermore, the maximum T/R shrinkage ratio at the macroscopic level (1.7) was found to be similar to the value of latewood tracheid (1.72). The earlywood showed high anisotropic, its T/R shrinkage ratio was 2.75. The macroscopic shrinkage was the result of the interaction of the tracheids of earlywood and latewood and was mainly dominated by latewood tracheids.

An experimental investigation on a locally fabricated dryer integrated with a novel solar air heater for the drying of potato slices

ABSTRACT Typical fuel-driven commercial dryers have excellent efficiency with homogeneous high-quality output, but they are beyond the access of farmers with limited agro land and financial resources. In this study, drying trials with potato slices were carried out utilizing a laboratory scale built drier coupled with an unique solar air heater. Assuming the set-up as mixed mode type solar dryer, performance of the dryer during the drying of potato slices was studied and the results were compared with that of open sun drying (OSD). The novel two pass solar air heater used in this project has aluminum turbulators arranged in staggered fashion. The absorber plate with aluminium turbulators present inside the double pass solar air heater reached a maximum temperature of 68°C. The average efficiency of the novel solar heater was about 72%. The moisture content of potato was reduced to 18.23% in 8 hours from 82.15%. The maximum thermal efficiency of the dryer was determined as 34%.The average specific energy requirement was estimated as 1.61 kWhkg−1 and the shrinkage ratio was found to be 0.2 at the end of 7 hours.

Application of blanching pretreatment in herbaceous peony (Paeonia lactiflora Pall.) flower processing: Improved drying efficiency, enriched volatile profile and increased phytochemical content

Although various techniques have been developed to dry herbaceous peony (Paeonia lactiflora Pall.) flowers, the dried products usually have a low retention level of bioactive compounds, which limits the valorization of peony-derived products. This work is the first to employ steam blanching (SB), high-humidity hot air impingement blanching (HHAIB), and vacuum-steam pulsed blanching (VSPB) before drying to improve the drying efficiency and quality of dried peony flowers. Results showed blanching pretreatment led to significant (p < 0.05) reductions in drying time by 7.02–40.35% and energy consumption by 6.86–39.96%, respectively. The final dried samples also exhibited reductions in browning degree by 30.93–62.89% and shrinkage ratio by 30.05–68.83%, respectively. Based on blanching pretreatment, the retention levels of bioactive compounds in dried samples were significantly (p < 0.05) improved. The dried samples blanched with VSPB possessed the highest contents of gallic acid (76.76 ± 1.75 mg/100 g DW), catechins (0.327 ± 0.010 mg/100 g DW), paeoniflorin (51.00 ± 1.41 mg/100 g DW), total phenolic (85.41 ± 1.81 mg GAE/100 g DW), flavonoid (11.00 ± 0.26 mg RE/100 g DW), and sugar (22.86 ± 0.13 g/100 g DW), thus causing superior antioxidant capacity. Furthermore, a total of 28 volatiles were identified, with alcohols (8.58–166.10 μg/g), alkanes (11.69–70.01 μg/g), and terpenes (5.89–47.93 μg/g) being the dominant contributors to the flavor of dried samples. This work provides insight for researchers to develop dried peony flowers with high added value using an energy-efficient strategy in the future.

Effect of vulcanization on deformation behavior of rubber seals: Thermal–mechanical–chemical coupling model, numerical studies, and experimental validation

Vulcanization molding has a significant impact on dimensional changes of rubber seals. Numerical analysis of this process can improve dimensional accuracy of molded sealing products. In this study, a stress–strain relationship model that considers thermal expansion, cold contraction, and shrinkage caused by a crosslinking reaction under the constraint of a mold boundary was established, a transient analysis method for thermal–mechanical–chemical coupling of the process from rubber seal vulcanization to mold opening was developed, and dimensional changes of the rubber seal in the mold and after cooling were predicted. Results calculated by the model were verified by the production of typical seals. The influences of vulcanization process parameters on changes in molded seal size were numerically analyzed. The numerical results showed that the dimensional shrinkage ratio increased nonlinearly from 3.2 % to 3.8 % when the vulcanization temperature increased from 165 to 185 °C, i.e., an increase of 0.206 % for every 1 % increase in shrinkage caused by the vulcanization reaction. These research results can be utilized in the design of vulcanization molds for high-precision rubber seals.

The formation mechanism of microcracks and fracture morphology of wood during drying

The surface checks or internal cracks from drying could significantly affect the processing and utilization of the wood. Therefore, it is of great significance to investigate the formation mechanism of cracks and reduce its occurrence. In this work, the development of cracking was quantified and its relationship with moisture content (MC) gradient and anisotropic shrinkage was analyzed. Results showed that the slight shrinkage occurred at the MC of 40%, and the shrinkage ratio at the end of drying was about 7.38% in the tangential (T) direction and 4.35% in the radial (R) direction. The shrinkage ratio of T/R in the MC range of 30%–15% was about 1.8, which was higher than that (1.65) in the MC range of 15%–5%. Cracks initiation was observed at average MC of 45%. The area and number of cracks reached a maximum at 15% MC. During the late stage of drying, the drying stress of the surface layer was reversed from tensile to compressive, which leads to the narrowing or closure of the cracks. Moreover, the fracture morphology of wood cells was observed at the microscopic level, indicating that the failure firstly occurred in the intercellular layer between the ray tissue and the tracheid in the latewood. The ray cells presented intact, and the lamellar structure between ray tissues and between the ray cells and the tracheids were the weak points of wood during drying. The results would contribute to keeping in minimum drying defects and improving the drying quality of wood.

Low-shrinkage biodegradable PBST/PBS foams fabricated by microcellular foaming using CO2 & N2 as co-blowing agents

Poly (butylene succinate-butylene terephthalate) (PBST) displays favorable foamability with the supercritical CO2 as the blowing agent, but the foams behave serious shrinkage behavior. In this work, a serious of fully biodegradable PBST/poly (butylene succinate) (PBS) microcellular foams with low volume shrinkage ratio were fabricated with the co-blowing agent of CO2 & N2. The presence of PBS can not only improve the rheological behavior, crystallization and mechanical properties to alleviate shrinkage process, but also play the role of nucleating agent to promote cell nucleation. With the increasing content of PBS, the cell size of the foam decreases from 25.0 μm to 7.03 μm, the cell density increases from 8.84×108 to 3.19×1010 cells/cm3 and the volume shrinkage ratio reduces from 62.10% to 47.81%. Furthermore, it is demonstrated that the introduction of N2 can inhabit the shrinkage behavior of PBST/PBS foams effectively. With the introduction of 12 MPa CO2 and 8 MPa N2, the volume expansion ratio of PBST/PBS10 microcellular foam can achieve 10.6-fold with good dimensional stability.

A Study on Dimensional Accuracy of a Vehicle Hood-Catch Considering Material Shrinkage of Polyamide 6 and Length-to-Volume Ratio Characteristic of a Shape

A hood-catch is a car part that fixes the vehicle’s hood to its body. This serves as a mechanism for opening and closing the engine bay of an automobile and prevents safety accidents in which the hood is opened while driving due to vibration generated from off-road conditions by firmly latching. Research regarding the overall improvement of products by injection molding, with analysis based on computer-aided engineering, is being actively conducted. However, research on the shrinkage rate considering the characteristics of parts’ shapes, such as length-to-volume ratio, is insufficient. Therefore, in this study, our research is concerned with (1) process improvement compared to the existing process using the design of an experimental method, (2) suggestion of a shrinkage-rate constant, considering both PA6 shrinkage ratio, which is a material characteristic, and length-to-volume ratio, which is a part shape characteristic, and (3) the effect of the proposed shrinkage rate on the accuracy of key dimensions of the hood-catch joint. The results of this study demonstrated that the shrinkage-rate constant needs to be considered simultaneously for both material characteristics and part shape characteristics. In particular, the shrinkage rates of the hood-catch’s pivot sub-assembly and open lever with reinforced PA6, with length-to-volume ratios of 1.24 × 10−3 and 3.10 × 10−3, respectively, are suggested as 0.2% and 0.5%.

Specific Surface Area Evolution and Shrinkage Control of Pre-Sintered Nickel Clusters

This study prepared pre-sintered clusters with fine nickel powders and proposed an effective method to predict and control the sintering shrinkage based on cluster size. Experiments were conducted to investigate the influence of the pre-sintering temperature and cluster size on the specific surface area and morphology of pre-sintered clusters as well as to validate the availability of the proposed shrinkage prediction method. The results show that the specific surface area decreases with an increasing pre-sintering temperature and slightly oscillates with an increasing cluster size. The linear shrinkage ratio is inversely proportional to the cluster size and decreases with an increasing pre-sintering temperature, which begins to drop rapidly at 500 °C and decreases from 19.05% to 3.18% at 800 °C. The experimental results are quite approximate to the predicted values, which strongly prove the availability of the proposed shrinkage prediction method.

A Metal Ion and Thermal-Responsive Bilayer Hydrogel Actuator Achieved by the Asymmetric Osmotic Flow of Water between Two Layers under Stimuli.

Shape-morphing hydrogels have drawn great attention due to their wide applications as soft actuators, while asymmetric responsive shape-morphing behavior upon encountering external stimuli is fundamental for the development of hydrogel actuators. Therefore, in this work, bilayer hydrogels were prepared and the shrinkage ratios (LA/LN) of the AAm/AAc layer to the NIPAM layer immersed in different metal ion solutions, leading to bending in different directions, were investigated. The difference in the shrinkage ratio was attributed to the synergistic effect of the osmolarity difference between the inside and outside of the hydrogels and the interaction difference between the ion and hydrogel polymer chains. Additionally, under thermal stimuli, the hydrogel actuator would bend toward the NIPAM layer due to the shrinkage of the hydrogel networks caused by the hydrophilic–hydrophobic phase transition of NIPAM blocks above the LCST. This indicates that metal ion and thermal-responsive shape-morphing hydrogel actuators with good mechanical properties could be used as metal ion or temperature-controllable switches or other smart devices.

Hydraulics of Wedge-shaped Flip Bucket to Investigate Flow Pattern with Retracted Bottom Plate

This study analyzed the flow pattern of a wedge-shaped flip bucket with a retracted bottom plate (WFB-R) that is quite different from conventional flip buckets. The flow pattern of the free jet release from WFB-R is determined by the relationship between water depth at the exit and wedge height. If the water depth is less than or equal to the wedge height, the free jet appears narrow and long, whereas if the water depth is greater, the free jet appears like a hammer. Hence, WFB-R offers the advantage of extending the free jet longitudinally, but its longitudinal length can be controlled, which allows it to avoid hitting the bank of the plunge pool. The experimental results indicate that, compared to constant-width flip buckets with retracted bottom plates (CFB-R), WFB-R reduces the maximum impact pressure on the plunge pool bottom to 70–86% of what it originally was. In addition, the flow structure of free jets issued from WFB-R was modeled using the k-ε turbulence model. The numerical results show that in the case of WFB-R, the shrinkage ratio should be less than or equal to a critical shrinkage ratio (0.63 for the present case) in order to stretch a free jet longitudinally. The length of the retracted bottom plate affects the longitudinal extension of the free jet. The longer the retracted bottom plate, the better the longitudinal stretching effect. The flow pattern is determined by the relationship between water depth at the exit of WFB-R and wedge height. Based on the projectile theory, a novel method was developed to predict the trajectory of free jets released from WFB-R by incorporating the average velocity, takeoff velocity coefficient, and takeoff angle coefficient. The Yangfanggou high dam project illustrates the application of WFB-R.

The behavior of the propagating velocity of rotating detonation waves and counter-rotating shock waves in a hollow combustor

The propagating velocity behavior, mathematical model and influencing factors of rotating detonation waves and counter-rotating shock waves in a hollow combustor with Laval nozzle are investigated. We use our in-house solver BYRFoam developed on OpenFOAM platform. The existence of the shock wave propagating in the opposite direction of the detonation wave in the combustor, called the counter-rotating shock wave, is observed for a wide range. The regular pattern of the propagation of the counter-rotating shock wave is studied and verified by experimental data. The propagating velocity behavior of rotating detonation waves and counter-rotating shock waves is discussed, and the mathematical model of the counter-rotating shock wave is proposed and verified. The results show that there is a clear quantitative relationship between the counter-rotating shock wave and the peak periodic undulation phenomenon of the pressure time curve, that is, the wave packet. This mathematical model connects the counter-rotating shock wave phenomenon in the experiment with the wave packet phenomenon in the experiment. The influencing factors of the counter-rotating shock wave are studied. The results show that increasing inlet total pressure and decreasing nozzle shrinkage ratio can significantly weaken the counter-rotating shock wave in a combustor. Based on this, the relevant parameters of rotating detonation engine (RDE) can be optimized to make the rotating detonation propagate more stable and therefore make the RDE operate more stable, which is of great significance to the practical application of RDE.

A Note on Procrustean Fittings of Noisy Configurations

When comparing two or more multidimensional scaling (MDS) configurations, one usually first eliminates meaningless differences by Procrustean transformations. Such fittings lead to a number of unresolved issues such as the typical shrinkage of the fitted configuration relative to the target or how to interpret major similarity measures under various conditions of noise in the data. We here prove that the shrinkage ratio is equivalent to the correlation of the coordinates of the target and the fitted configuration. Thus, in real-life applications, the fitted configuration is always smaller than the target configuration. Both coefficients approach 0 as the noise level goes up. The congruence coefficient of the configurations' distances, in contrast, remains at a high level even in case of pure noise, falsely suggesting that the configurations are somewhat similar. This is important information for the user of Procrustean analyses.