bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution and protection of avian specialization in Europe
Authors: Benedetti Yanina , Morelli Federico , Callaghan Corey T. , Fuller Richard
Published: October 2021

Aim

We assessed the spatial distribution of four different types of avian specialization throughout Europe, identifying landscape features associated with specialization and quantifying where the Natura 2000 network intersects with areas of high avian specialization.

Location

Europe.

Time period

Present day.

Taxa studied

European breeding birds.

Methods

We used the European Atlas of breeding birds and four avian specialization measures (diet, foraging behaviour, foraging substrate and habitat). We calculated specialization richness and identified geographical hotspots for each of these ecological traits. We tested whether elevational gradient, landscape heterogeneity or dominant land use predicted each type of specialization richness. We determined which types of European protected areas are most associated with higher specialization richness.

Results

Diet and foraging substrate specialists increased with elevation, whereas richness of foraging behavioural specialists decreased. There was a greater richness of dietary and habitat specialists in forests than in other environments. The Natura 2000 areas declared under Bird and both directives (Birds and Habitats) intersected with a high dietary, foraging substrate and habitat specialist richness. The richness of foraging behaviour specialists was high in Birds directive areas. Single and multiple hotspots of specialization were greater in protected than non‐protected areas. However, almost 30% of specialization hotspots did not intersect with protected areas.

Main conclusions

Our findings suggest that higher levels of avian specialization in Europe are positively associated with elevation and forested land cover. Importantly, we found that the Natura 2000 network supports all types of avian ecological specialization, albeit mainly in areas declared under both directives.
Accuracy of Flowmeters Measuring Horizontal Flow in Fractured‐Rock Simulators
Authors: Bayless E. Randall
Published: October 2021

Laboratory evaluations of flowmeter response to flow in fractured‐rock simulators are needed to improve understanding of data collected in field settings. The ability of flowmeters to accurately measure the velocity and direction of water flowing between parallel plates was used as a surrogate for instrument response in fractured‐rock aquifers. A colloidal borescope flowmeter and a heat‐pulse flowmeter were deployed in a fractured rock simulator with 4‐inch and 6‐inch inner‐diameter, uncased wells with 0.39‐ and 1.0‐inch fracture apertures and groundwater velocities from 35 to 975 ft/d. The colloidal borescope measurements and applied velocities were positively correlated in all wells and apertures (the coefficient of determination [r2] = 0.61–0.89) and most accurately measured direction at higher velocities. The mean directional error in colloidal borescope measurements was less than 17° in 6‐inch wells and 31° in the 4‐inch wells at velocities between 92 and 958 ft/d. Heat‐pulse flowmeter measurements were 0.001 to 0.004 times less than applied rates and may indicate that water was moving around rather than through the instrument's integrated packer. The mean directional error of heat‐pulse flowmeter measurements were about 18 and 42° in the 0.39‐ and 1.0‐inch fractures, respectively, for groundwater velocities within the manufacturer's suggested range of application (0.5–100 ft/d). Measurements made at vertical increments and fracture positions in the well using the colloidal borescope indicate that laminar flow occurs within the central 50% of the fracture but measurements above or below are likely affected by eddy currents.
Proximate, mineral, amino acid composition, phenolic profile, antioxidant and functional properties of oilseed cakes
Authors: Kaur Manpreet , Singh Balwinder , Kaur Amritpal , Singh Narpinder
Published: October 2021

Proximate, minerals, amino acids (AAs), phenolic composition, antioxidant and functional properties of flaxseed (FSC), sesame (SSC), mustard (MSC), nigella (NSC) and groundnut (GSC) seedcakes were studied. SSC exhibited higher ash and fat contents while GSC and FSC had more protein and mineral contents (P, Mg, Mn and Cu), respectively. The total flavonoids, phenolics and antioxidant activity were higher in NSC (18.60 mg QE g−1), MSC (5.12 mg GAE g−1) and FSC (12.28 µmol TE g−1), respectively. NSC exhibited the highest oil absorption capacity (2.10 g g−1) and emulsifying activity index (89.52 m2 g−1). Twenty‐one AAs including citrulline and ɣ‐aminobutyric acid were detected in oilseed cakes (OSC). MSC had more essential AAs (methionine, isoleucine, tryptophan, threonine and lysine) while GSC had more total hydrophobic, acidic and basic AAs. Syringic acid and rutin were identified as major phenolic compounds in GSC and MSC, respectively. The total free phenolic acids were more in GSC while FSC had high total bound phenolic acids and flavonoids. OSC can be utilised in food products as a supplement to improve nutritional properties.
Tuning stoichiometry of high‐entropy oxides for tailorable thermal expansion coefficients and low thermal conductivity
Authors: Xu Liang , Su Lei , Wang Hongjie , Gao Hongfei , Lu De , Peng Kang , Niu Min , Cai Zhixin
Published: October 2021

Thermal barrier coating materials with proper thermal expansion coefficient (TEC), low thermal conductivity, and good high‐temperature stability are of great significance for their applications in next‐generation turbine engines. Herein, we report a new class of high‐entropy (La0.2Sm0.2Er0.2Yb0.2Y0.2)2CexO3+2xwith different Ce4+contents synthesized by a solid‐state reaction method. They exhibit different crystal structures at different Ce4+content, including a bixbyite single phase without Ce4+doping (x = 0), bixbyite‐fluorite dual‐phase in the RE2O3‐rich region (0 < x < 2), and fluorite single phase in the stoichiometric (x = 2) and CeO2‐rich region (x> 2). The high‐entropy (La0.2Sm0.2Er0.2Yb0.2Y0.2)2CexO3+2xexhibit tailorable TECs at a large range of 9.04 × 10–6–13.12 × 10–6°C–1and engineered low thermal conductivity of 1.79–2.63 W·m–1·K–1. They also possess good sintering resistance and high‐temperature phase stability. These results reveal that the high‐entropy (La0.2Sm0.2Er0.2Yb0.2Y0.2)2CexO3+2xare promising candidates for thermal barrier coating materials as well as thermally insulating materials and refractories.
The evolution of material stock research: From exploring to rising to hot studies
Authors: Fu Chenling , Zhang Yan , Deng Tianjie , Daigo Ichiro
Published: October 2021

Material stocks in buildings, infrastructure, and durable products play multiple roles in environmental and socioeconomic systems throughout their life cycle. After half a century of exploration, the study of material stocks has led to the development of a knowledge system. However, an overall picture of the evolution of knowledge in this field is lacking. With the aid of CiteSpace, a science mapping tool, we review 395 publications and find that the study of material stock experienced three obvious stages: initial exploration (1973–2005); rising period (2006–2016); and a hot period (2017–2020). The evolution of material stock research shows a clear objective‐oriented mode. As research objectives evolved from macroscopic observation to refined management of materials, the main research content changed from observational accounting to exploring the application, role, and service functions of material stocks, especially from the perspective of systematic metabolism under the complex background of social transformation. Accounting items shifted from an initial focus on metallic materials to a broader set of materials and product stocks, and from accounting of a single category to multi‐category accounting. The scale of research correspondingly shifted from the national and global scale to the urban and community scale which can serve refined management. These changes also led to in‐depth and detailed study of the role and function of stocks. In the future, scholars should continue to explore and apply microscale models, “whiten” the black box in large scale research; focus on recycling of urban minerals and electronic wastes. Mapping the transformation of raw materials into products by combining material properties and product functions is crucial to concretely implement a circular economy. Differentiation, specialization, combination of approaches, and sub‐categorical and sub‐regional coefficients will be the key to future refined, lean, and precise accounting.
Medicaid Cost and Reimbursement for Low‐Risk Prenatal Care in the United States
Authors: Baker Mary V. , Butler‐Tobah Yvonne S. , Famuyide Abimbola O. , Theiler Regan N.
Published: October 2021

Introduction

We calculate the financial margins for delivery of routine antenatal care as reimbursed by Medicaid. Prenatal care cost varies with overhead, health care provider type, and number of office visits. Antenatal care is only one component of the global maternity bundle, which also includes intrapartum and postpartum care.

Methods

Time for provision of low‐risk antenatal care was determined prospectively from a study of 133 low‐risk pregnant patients. Health care provider time cost was estimated using mean wages for obstetricians and midwives. Margins were estimated by subtracting cost of provider services and overhead for the antenatal component of maternity care from total Medicaid reimbursement for the pregnancy global package (CPT 59400) using 2015 dollars. The maternity bundle elements of routine prenatal laboratory tests, ultrasounds, intrapartum care, and postpartum care were not included in our analysis of cost components.

Results

Patients received an average of 215 minutes of direct provider time per pregnancy. At the 50th percentile for physician payment and assuming overhead is 53.4% of revenue, practice margins varied by state from −$1067 to +$675, with a median of −$357. Median margins for midwifery care were +$15, with a range of −$579 to +$885. Margins were negative if overhead costs exceeded 33% of revenue for physician care and 55% of revenue for midwifery care.

Discussion

In many states, Medicaid reimbursement for the global maternity package is less than the actual cost of antenatal care alone. Improving reimbursement or decreasing costs is necessary to make maternity care more cost‐effective.
Traditional prenatal and postpartum food restrictions among women in northern Lao PDR
Authors: Smith Taryn J. , Tan Xiuping , Arnold Charles D. , Sitthideth Dalaphone , Kounnavong Sengchanh , Hess Sonja Y.
Published: October 2021

Culturally determined food restrictions are common among pregnant and postpartum women in Asia. This study aimed to describe perinatal dietary restrictions, factors associated with food avoidances and attainment of minimum dietary diversity (MDD‐W) among women in Lao PDR. Mother–child (aged 21 days to <18 months) dyads (n = 682) were enrolled into a cohort study in northern Lao PDR and interviewed at one time point postpartum. During pregnancy and postpartum, 1.6% and 97% of women reported following dietary restrictions, respectively. Cluster analysis identified four distinct postpartum dietary patterns: most restrictive (throughout first 2 months postpartum); least restrictive; 2 weeks highly restrictive and 1 month highly restrictive, followed by 19%, 15%, 5% and 62% of women, respectively. Greater maternal age, gravidity and higher household socioeconomic status were associated with allowing more diverse foods, while women from food insecure households followed more restrictive diets for longer. Women belonging to the Hmong ethnic group followed a highly restrictive diet of white rice and chicken for the first month postpartum. MDD‐W was achieved by 10% of women restricting their diet at the time of the interview compared with 17% of women who were consuming their normal diet (p = 0.04). Postpartum dietary restrictions are widespread among women in northern Lao PDR. These highly restrictive diets, low dietary diversity and food insecurity likely contribute to micronutrient deficiencies in women that may have important consequences for their breastfed infants through reduced breastmilk micronutrient content, which requires further exploration. Culturally appropriate strategies to increase micronutrient intakes among women should be considered.
“Burnt‐out” progressive multifocal leukoencephalopathy in idiopathic CD4+ lymphocytopenia
Authors: Fukumoto Tatsuya , Sakashita Yasuhiro , Katada Fumiaki , Takeuchi Ryoko , Miyamoto Ryosuke , Izumi Yuishin , Sato Susumu , Shibayama Hidehiro , Takahashi Kenta , Suzuki Tadaki , Nakamichi Kazuo , Murayama Shigeo , Fukutake Toshio
Published: October 2021

Progressive multifocal leukoencephalopathy (PML) is a fatal disease caused by John Cunningham virus (JCV) infection; however, a growing number of PML patients now survive longer and achieve remission, largely due to the advent of combination antiretroviral therapy. Several reports have suggested that the pathology in such patients presents only chronic demyelination without characteristic cellular changes, being referred to as “burnt‐out” PML. On the other hand, our knowledge of “burnt‐out” PML is still substantially limited, especially in patients with non‐human immunodeficiency virus infection. Here, we report a case of PML associated with idiopathic CD4+ lymphocytopenia (ICL) who presented with spontaneous remission and survived for 11 years after onset. Notably, postmortem examination revealed surprisingly broad “burnt‐out” lesions lacking the classic histopathological findings. However, pathogenic JCV‐specific DNA sequences was still present in the autopsied brain tissue. This case suggests that complete remission can be achieved with a persistent presence of JCV‐specific pathogenic sequences, even after a catastrophic infection. Considering that there have been a few reported cases of PML with ICL with long survival, the long‐term survival of our case may share a favorable immunological response that is unique to a subgroup of ICL.
ISSR genotyping of Phoenix theophrasti natural populations in Turkey and Crete (Greece) and P. dactylifera
Authors: Boydak Melih , Teker Tuğba , Gazdağli Aylin , Thanos Costas A. , Çalişkan Servet , Kaltsis Apostolis , Çalikoğlu Tozlu Emine , Fournaraki Christini , Albayrak Gülruh
Published: October 2021

Intraspecific and interspecific diversity between Phoenix theophrasti individuals (92 from Turkey and 70 from Crete, Greece) and P. dactylifera specimens (28 from Turkey) were investigated by inter‐simple sequence repeat (ISSR) analysis. A total of 45 polymorphic fragments, 360–3454 bps long, were produced. Intraspecific diversity for P. dactylifera was 26.63% and similarities ranged between 0.5 and 1. In the constructed dendrogram, P. dactylifera specimens clustered together in the first main group, outside branches consisting of P. theophrasti samples that generated the second main group. The intraspecific diversity for Turkish P. theophrasti populations was found to be 18.60% and for Cretan populations 13.45%. Antalya–Kumluca–Karaöz samples were grouped outside the branches of the remaining P. theophrasti samples. All three Cretan populations formed their own, separate branch. Datça–Eksera Stream samples together with two Datça–Hurmalıbük specimens constituted a group excluding Datça–Hurmalıbük and Bodrum–Gölköy specimens. Five Bodrum–Gölköy genotypes were clustered separately. Gene flow (Nm) values among populations were estimated from 0.157 to 59.615. AMOVA analysis revealed the percentages of variance among and within Phoenix populations: 73% and 27%, respectively. The first three principal coordinate components accounted for 37.60, 29.32 and 20.04%, respectively, thus the total variance obtained from the first three principal coordinate components was 86.96%. A positive correlation between geographic and genetic distances of populations was detected by Mantel tests (Rx,y = 0.44, p = 0.04). The populations were classified into four clusters by STRUCTURE analysis, supported the PCoA data. To conclude, ISSR results support that P. dactylifera and P. theophrasti are different species. Moreover, the findings not only revealed relationships between natural Phoenix theophrasti populations but also supported the identification of the P. theophrasti individuals that are phenotypically differentiated in the divided Bodrum–Gölköy population (P. theophrasti subsp. golkoyana).
The effects of slow deep breathing on microvascular and autonomic function and symptoms in adults with irritable bowel syndrome: A pilot study
Authors: Katherine Jurek Mary , Seavey Hannah , Guidry Meredith , Slomka Emily , Hunter Stacy D.
Published: October 2021

Background

Irritable bowel syndrome (IBS) is linked to disruptions in sympathovagal balance, which could impair vascular homeostasis and cause IBS symptoms. Studies have shown reductions in sympathetic activity following a single slow, deep breathing (SDB) bout in healthy adults; however, no studies have investigated its chronic effects in IBS. The purpose of this study was to evaluate the feasibility and impact of a SDB intervention on microvascular and autonomic function and symptoms in adults with IBS.

Methods

Fourteen participants (ages 18–65 years) with IBS were randomly assigned to 4‐week SDB or control conditions. The SDB group completed a 20‐min video 5 times weekly while the control group maintained their normal activities. Microvascular endothelial function was measured using laser Doppler in response to thermal provocation and expressed as cutaneous vascular conductance at 39°C relative to a maximum response at 43.5°C (%CVCmax). Heart rate variability (HRV) and post‐exercise heart rate recovery (HRR) were employed as surrogate measures of autonomic function. IBS symptoms were assessed using the IBS‐Severity Scale (IBS‐SS).

Key Results

Thirteen participants (6 controls and 7 SDB) completed the study. Age (p = 0.541) and body mass index (p = 0.157) were similar between groups. In the SDB group, %CVCmax increased from 45% to 59% (p < 0.00001) after the 4‐week intervention. HRV, HRR, and IBS‐SS scores were unaltered.

Conclusions

and Inferences.

These results demonstrate the feasibility of a SDB intervention in adults with IBS and suggest improvements in microvascular function in the absence of changes in symptoms or autonomic function in this population.
The Application of H‐Loop in Arthroscopic Knotless Double‐Row Rotator Cuff Repairs
Authors: Guo Jiang , Hou Jingyi , Yu Menglei , Alike Yamuhanmode , Long Yi , Tang Yiyong , Li Qingyue , Li Fangqi , Zhang Yuhao , Ali MaslahIdiris , Zheng Zhenze , Meng Ke , Wang Peng , Yang Rui
Published: October 2021

Objective

To determine the functional outcomes after a novel method of H‐loop knotless double‐row technique in patients with rotator cuff tears.

Method

From June 2020 to September 2020, a total of six patients (five women, one man) with arthroscopic rotator cuff repair using the H‐loop knotless double‐row technique were enrolled in our study. The average age is 54 years (range: 50–61 years). The preoperative and final follow‐up clinical outcome were evaluated using the American Shoulder and Elbow Surgeons (ASES) score, visual analog scale (VAS), University of California Los Angeles (UCLA) score, and Constant–Murley score. The active shoulder range of motion (ROM) was also collected preoperatively and postoperatively at the final follow‐up (forward flexion and abduction). Accordingly, intraoperative and postoperative complications were observed as well.

Result

There were six patients that underwent arthroscopic rotator cuff repair using the H‐loop knotless double‐row technique. The average follow‐up period was 7.52 ± 0.70 months. The VAS, UCLA, ASES, and Constant–Murley scores improved from 5 ± 2.45, 15.67 ± 3.44, 47.67 ± 17.41 and 49.17 ± 8.98 preoperatively, to 0.83 ± 0.75, 36.27 ± 3.83, 91.67 ± 10.76 and 85.83 ± 4.31 at the final follow‐up, with statistical significances of P = 0.009, P < 0.001, P = 0.006, and P = 0.001, respectively. Meanwhile, the active shoulder ROM (forward flexion and abduction) improved from 135.00 ± 46.80 and 125 ± 56.48 preoperatively, to 173.67 ± 4.13 and 172 ± 3.27 at final follow‐up, respectively (P = 0.082, P = 0.088). During the follow‐up, there were no postoperative complications such as wound‐site infection, nerve or vessel damage, subcutaneous hematoma, and suture anchor problems.

Conclusion

With the benefit of reducing the possibility of strangulation and blood supply affection for the rotator cuff, The H‐loop knotless double row technique may be an alternative method to significantly improve subjective functional outcomes and increase the healing rate of medium‐sized rotator cuff tears with degeneration issues and poor tissue quality.
ProteinCand comparative biochemical changes in dogs treated with percutaneous transvenous coil embolization of congenital intrahepatic portosystemic shunts
Authors: Sunlight Crystal , Weisse Chick , Berent Allyson , Tozier Eric
Published: October 2021

Objective

To evaluate protein C (PC) activity after intrahepatic portosystemic shunt (IHPSS) percutaneous transvenous coil embolization (PTCE) in dogs; to identify if PC is associated with clinical status after intervention, and to compare PC with standard biochemical values.

Study design

Retrospective case series.

Animals

Forty‐seven client‐owned dogs with IHPSS undergoing PTCE.

Methods

Records were reviewed for preoperative and postoperative PC, hematocrit (HCT), mean corpuscular volume (MCV), albumin (ALB), and blood urea nitrogen (BUN). Ultimate clinical status was classified as excellent, fair, or poor, based on ongoing medical management and the presence of clinical signs. Intrahepatic portosystemic shunt was considered to be completely or incompletely occluded intraoperatively based on angiography.

Results

Postoperative PC activity increased in 37/47 (78.7%) dogs with a mean increase of 38.7% ± 2.1%. Ultimate postoperative clinical status was excellent in 16/43 (37.2%), fair in 19/43 (44.2%), and poor in 8/43 dogs (18.6%). No association was detected between preoperative PC (46.8% ± 1.8%) and ultimate clinical status but mean postoperative PC (75.7% ± 1.4%), HCT, MCV, ALB, and BUN were higher in dogs with excellent clinical status. Postoperative PC activity was higher when shunts were completely occluded (96.3% ± 10.9%), which was a finding associated with excellent status.

Conclusion

Postoperative, but not preoperative, PC activity was higher in dogs with better ultimate clinical status. Similar trends were noted in standard hematological and biochemical values. Complete occlusion of shunts was associated with a higher postoperative PC and superior ultimate clinical status.

Clinical significance

Postoperative PC may provide valuable information about the success of PTCE for IHPSS as it relates to the ultimate status and the need for additional procedures.
Hybrid Multi-Objective Optimization Approach in Water Flooding
Authors: Al-Aghbari Mohammed , Gujarathi Ashish M. , Al-Wadhahi Majid , Chakraborti Nirupam
Published: October 2021

Non-dominated sorting genetic algorithm, second version (NSGA-II) is used as a stochastic optimization technique successfully in different engineering applications. In this study, a data-driven optimization strategy based upon evolutionary neural network (EvoNN) algorithm is developed for providing input into NSGA-II optimization. Evolutionary neural network data-driven model is built and trained using initial solutions generated by NSGA-II optimization coupled with the reservoir simulation model. Evolutionary optimization incorporated in the EvoNN strategy is applied in the trained data-driven model to generate the Pareto optimal solution, which is then used as a guiding input into NSGA-II optimization. The described method is applied in two case studies (i.e., Brugge field model and water injection pattern model). The Pareto optimal solutions obtained with data-driven model guided NSGA-II in both models show improvement in convergence and diversity of the solution. The convergence to the Pareto optimal solution has improved by 9% for case-1 (i.e., Brugge field) and by 43% for case-2 (i.e., water injection pattern model). In addition, the Pareto optimal solution obtained by the proposed hybridization has shown improvement in the water–oil ratio (WOR) up to 6% in the Brugge field and up to 97% in the water injection pattern model. This improvement can lead to wide applications in using evolutionary optimizations in real-field simulation models at acceptable computation time.
Corrugated Diaphragm Actuator for Soft Robotic Applications
Authors: Erel Veysel , Lindsay Alexandra R. , Singh Inderjeet , Wijesundara Muthu B. J.
Published: October 2021

Soft robotics is projected to have a significant impact on healthcare, industry, and the military to deliver assistance in rehabilitation, daily living activities, repetitive motion tasks, and human performance augmentation. Many attempts have been made for application-specific robotic joints, robots, and exoskeletons using various actuator types, materials, and designs. The progress of creating soft robotic systems can be accelerated if a set of actuators with defined characteristics were developed, similar to conventional robotic actuators, which can be assembled to create desired systems including exoskeletons and end effectors. This work presents the design methodology of such a modular actuator, created with a novel corrugated diaphragm that can apply linear displacement, angular displacement, and force. This modular actuator approach allows for creating various robotic joints by arranging them into different configurations. The modular corrugated diaphragm actuator concept was validated through numerical simulation, fabrication, and testing. Linear displacement, angular displacement, and force characteristics were shown for a single module and in multi-module assemblies. Actuator assemblies that are configured in a serial and parallel manner were investigated to demonstrate the applicability and versatility of the concept of the modular corrugated diaphragm actuator for creating single and multi-degree-of-freedom joints.
Influence of Surface Structure on Performance of Inkjet Printed Cathode Catalyst Layers for Polymer Electrolyte Fuel Cells
Authors: Park Kayoung , Wei Yuting , So Magnus , Noh Tae Hyoung , Kimura Naoki , Tsuge Yoshifumi , Inoue Gen
Published: October 2021

The structure of the cathode catalyst layer (CCL) is critically important for improving the performance, durability, and stability of polymer electrolyte fuel cells (PEFCs). In this study, we designed CCLs with a three-dimensional (3D) structure that could increase the surface area of the CCLs to decrease their oxygen transfer resistance. The CCLs were fabricated using an inkjet printing method, and the electrochemical performance of the CCLs in a membrane electrode assembly was evaluated using an actual cell. The results showed that at high Pt loadings, the performance of the CCL with the 3D structure was superior to that of the flat structure. In particular, at a high current density, which is related to mass transport resistance, the two structures exhibited a significant difference in performance. At a Pt loading of 0.3 mg/cm2, the CCL with the 3D structure showed the highest maximum power density among all the CCLs investigated in this study. This indicates that the 3D structure decreases the oxygen transfer resistance of the CCL. Overall, the 3D structure provided improved morphological and microstructural characteristics to the CCL for fuel cell applications.
Hydrodynamic Coefficients of a Floater Near a Partially Reflecting Seawall in the Presence of an Array of Caisson Blocks
Authors: Vijay K. G. , Koley S. , Trivedi K. , Nishad C. S.
Published: October 2021

In the present study, surface gravity wave scattering and radiation by a freely floating rectangular buoy placed near a partially reflecting seawall and in the presence of an array of caisson blocks are analyzed. Various hydrodynamic parameters related to the wave scattering and radiation, such as the added mass and radiation damping coefficients, correspond to sway, heave, and roll motions of the floating buoy, horizontal force, vertical force, and moment acting on the floating structure, and horizontal wave force acting on the partially reflecting seawall, are studied for a variety of wave and structural parameters. The study reveals that the resonating pattern in various hydrodynamic coefficients occurs for moderate values of the wavenumber. Furthermore, when the distance between the floater and the sidewall is an integral time of half wavelength, the resonating behavior in the sway, heave, and roll added masses, and associated damping coefficients appears, and the aforementioned hydrodynamic coefficients change rapidly around this zone. These resonance phenomena can be diminished significantly with appropriate positioning of the floater with respect to the sidewall and in the presence of partially reflecting seawall.
Passive Drag Reduction Technology Using Microfiber Coatings
Authors: Hasegawa Mitsugu , Sakaue Hirotaka
Published: October 2021

Engineered surfaces and coatings can passively manipulate flow over a bluff-body without significant retrofitting and are of great technological interest for a broad range of applications in the engineering field. A microfiber coating with a hair-like structure is developed and studied as a passive drag reduction method for flow over a cylinder that features both attached and separated flow. The impact of the microfiber coating on drag is experimentally investigated at a Reynolds number of 6.1 × 104 based on the cylinder diameter. Microfiber coatings of various lengths between 1.1% and 8.0% of the cylinder diameter are fabricated using flocking technology and applied to various positions on the cylinder surface between the leading and trailing edges. It is shown that the microfiber length and location are both influential parameters in drag reduction. Two types of drag reduction can be seen depending on the location of the microfiber coating: (1) Drag is reduced significantly if the microfiber coating is applied before flow separates over the cylinder (2) Drag is reduced moderately if the microfiber coating is applied after the point of flow separation on the cylinder. The former case’s best performance is achieved with a microfiber length of less than 1.8% of the cylinder diameter. The latter case shows better performance with relatively long fibers, where the microfiber’s length is greater than 3.3% of the cylinder diameter.
A High-Order Flux Reconstruction Method for 2-D Vorticity Transport
Authors: Gharakhani Adrin
Published: October 2021

A compact high-order finite difference method on unstructured meshes is developed for discretization of the unsteady vorticity transport equations (VTE) for 2-D incompressible flow. The algorithm is based on the Flux Reconstruction Method of Huynh [1, 2], extended to evaluate a Poisson equation for the streamfunction to enforce the kinematic relationship between the velocity and vorticity fields while satisfying the continuity equation. Unlike other finite difference methods for the VTE, where the wall vorticity is approximated by finite differencing the second wall-normal derivative of the streamfunction, the new method applies a Neumann boundary condition for the diffusion of vorticity such that it cancels the slip velocity resulting from the solution of the Poisson equation for the streamfunction. This yields a wall vorticity with order of accuracy consistent with that of the overall solution. In this paper, the high-order VTE solver is formulated and results presented to demonstrate the accuracy and convergence rate of the Poisson solution, as well as the VTE solver using benchmark problems of 2-D flow in lid-driven cavity and backward facing step channel at various Reynolds numbers.
Aeroacoustic Analysis of a UAV Propeller Operable at Various Altitudes
Authors: Song Ji-Hun , Jang Seungsoo , Kim Youn-Jea
Published: October 2021

With technological development and the wide application range of unmanned aerial vehicles (UAVs), the regulation of UAV altitude limits in many countries is further alleviated, and the problem of UAV noise pollution has emerged with the recent advent of urban air mobility (UAM) and personal air vehicle (PAV) markets. In this study, one typical propeller, the T-motor 15 × 5 propeller, was analyzed by use of the commercial CFD software, ANSYS FLUENT V19.3. The effects of gravity and convection were analyzed to determine the noise characteristics at altitude using the FW-H equation. A high-altitude drone, which operates at heights from 0 to 10 km with 1,000 to 5,000 revolutions per minute, was analyzed using the steady-state k-ω SST turbulence model. And using the steady-state data to initialize values, an unsteady analysis was performed with the LES turbulence model. The time step was divided based on the 1-degree rotational time, and the velocity residual on each axis was calculated until a value of 10−7 or less was achieved and there was no fluctuation of thrust, at which point it was considered converged. The CFD results were validated with the experimental results for thrust and their results show that the maximum error was 8.64%. The overall sound pressure level was calculated, and noise characteristics in the audible frequency range according to receiver points were also compared. Through this study, thrust and noise data according to altitude were provided. The aerodynamic and aeroacoustic characteristics at high-altitudes, which are generally difficult to measure by experiment, are also presented. Therefore, the appropriate operating altitudes and rotational speeds will be presented through the aeroacoustics analysis corresponding to operational altitude, and the basic research data can then be applied to upcoming unmanned aircraft system (UAS) market.
Impact of Flow Characteristics on the Pressure Distribution on Sluice Gates
Authors: Steppert Michael , Epple Philipp , Malcherek Andreas
Published: October 2021

The pressure distribution on sluice gate walls was investigated in this paper, based on CFD simulations. The flow characteristics impacting the pressure distribution were analyzed. Based on this analyzation, a new parametrization approach for the gate pressure distribution is derived for both, standard sluice gates and inclined sluice gates. Based on these investigations the impact of 3D flow characteristics on the pressure profile at the sluice gate wall is presented and discussed in detail.
Shock-Induced Multiphase Instability in a High Volume Fraction Finite-Thickness Particle Layer
Authors: Rollin Bertrand , Ouellet Frederick , Durant Bradford , Koneru Rahul Babu , Balachandar S.
Published: October 2021

We study the interaction of a planar air shock with a perturbed, monodispersed, particle curtain using point-particle simulations. In this Eulerian-Lagrangian approach, equations of motion are solved to track the position, momentum, and energy of the computational particles while the carrier fluid flow is computed in the Eulerian frame of reference. In contrast with many Shock-Driven Multiphase Instability (SDMI) studies, we investigate a configuration with an initially high particle volume fraction, which produces a strongly two-way coupled flow in the early moments following the shock-solid phase interaction. In the present study, the curtain is about 4 mm in thickness and has a peak volume fraction of about 26%. It is composed of spherical particles of d = 115μm in diameter and a density of 2500 kg.m−3, thus replicating glass particles commonly used in multiphase shock tube experiments or multiphase explosive experiments. We characterize both the evolution of the perturbed particle curtain and the gas initially trapped inside the particle curtain in our planar three-dimensional numerical shock tube. Control parameters such as the shock strength, the particle curtain perturbation wavelength and particle volume fraction peak-to-trough amplitude are varied to quantify their influence on the evolution of the particle cloud and the initially trapped gas. We also analyze the vortical motion in the flow field. Our results indicate that the shock strength is the primary contributor to the cloud particle width. Also, a classic Richtmyer-Meshkov instability mixes the gas initially trapped in the particle curtain and the surrounding gas. Finally, we observe that the particle cloud contribute to the formation of longitudinal vortices in the downstream flow.
PIV Visualization of Flow Around Airfoil Controlled by Synthetic Jet Actuators at Shear-Layer and Wake Instability Frequencies
Authors: Yang Eric , Sullivan Pierre E.
Published: October 2021

The response of a separated boundary layer to synthetic jet flow control at the global wake instability (F+ ≈ 𝒪(1)) and the shear-layer instability (F+ ≈ 𝒪(10)) measured by particle image velocimetry are presented. The visualization shows that in each of the control cases, coherent vorticity develops and breaks down into a turbulent wake. When the jets are actuated by burst-modulation at the wake instability frequency, they induce regular formation and detachment of large-scale vorticity to form a wide turbulent wake. Excitation at the shear-layer instability frequency, on the other hand, produces a train of alternating velocity fluctuations in the boundary layer which dissipate to a narrower wake. Proper orthogonal decomposition of the velocity fields show that the physical extent of the jet-induced coherent structures is decreased with increasing addition of momentum for both excitation frequencies.
Modeling of Cube Array Roughness: RANS, LES, and DNS
Authors: Altland Samuel , Xu Haosen H. A. , Yang Xiang I. A. , Kunz Robert
Published: October 2021

Flow over arrays of cubes is an extensively studied model problem for rough wall turbulent boundary layers. While considerable research has been performed in computationally investigating these topologies using DNS and LES, the ability of sublayer-resolved RANS to predict the bulk flow phenomena of these systems is relatively unexplored, especially at low and high packing densities. Here, RANS simulations are conducted on six different packing densities of cubes in aligned and staggered configurations. The packing densities investigated span from what would classically be defined as isolated, up to those in the d-type roughness regime, filling in the gap in the present literature. Three different sublayer-resolved turbulence closure models were tested for each case; a low Reynolds number k-ε model, the Menter k-ω SST model, and a full Reynolds stress model. Comparisons of the velocity fields, secondary flow features, and drag coefficients are made between the RANS results and existing LES and DNS results. There is a significant degree of variability in the performance of the various RANS models across all comparison metrics. However, the Reynolds stress model demonstrated the best accuracy in terms of the mean velocity profile as well as drag partition across the range of packing densities.
Flow Characterization of an Industrial Size Francis Turbine Operating at Ultra-Low Load – The Effect of Water Injection
Authors: Altimemy Muhannad , Caspar Justin , Watheq Saif , Oztekin Alparslan
Published: October 2021

Large Eddy Simulations (LES) are carried out for a Francis turbine operating at an ultra-low load with and without injection. The flow rate of the turbine is 40% of the design value. The injection aims to improve turbine operation for the already unstable base case away from the design flow rate. Tangential water injection was introduced through the draft tube wall in the same and opposite runner rotation direction. The injection angle was varied (15°, 30°, 45° and 60°). Two water injection rates were applied at 4% and 8 % of the optimal design flowrate. While injection with the 4% rate and 30° in the opposite runner rotation direction helped reduce pressure fluctuations downstream of the injection inlets; no injection configuration could completely mitigate the power and pressure fluctuations. The injection was found to increase the amplitude of pressure fluctuations close to the injection inlets by 2 to 20 times the magnitude of fluctuations without injection. There was a slight reduction in mean power production (4–10% loss) by injection. The high amplitude fluctuations were observed in power signals with and without the injection.
Detailed Analysis of Fiber Motion in Human Nasal Airways
Authors: Li Jiang , Ma J. W. , Tu J. Y. , Tian L. , Ahmadi G.
Published: October 2021

Information on the fiber particle transport and deposition in human nasal airways is of great importance in inhalation toxicology study. Due to the complex interactions between the inhaled aerosol particles and human respiratory airways, the particles’ toxicity varies with their chemical composition, size, and shape. In the earlier computational study of fiber particle motion in human nasal cavities, overall deposition efficiency curves were evaluated and compared with the available experimental data. The majority of investigations were on micron-scale fiber particles, and the observed deposition fraction is strongly affected by fiber inertial impaction and the geometry of the cavity. The fiber characterization by its equivalent spheres is still not entirely fully understood. Limited existing evidence indicated that, when benchmarked by the impaction parameter, spherical particles tend to have a higher deposition fraction than that of the elongated fiber particles in the nasal cavity. More data is needed to elaborate on these observations and reveal the underlying physics. A more profound understanding of fiber transport in human airways may be obtained by comparing the fibrous particle deposition to that of the spherical particles.

In this study, simulations of transport and deposition of elongated particles in a realistic human nasal cavity model for a steady laminar airflow rate were performed. FLUENT 19.2 was used to solve the airflow conditions. The elongated ellipsoidal particle transport and deposition were simulated using the coupled translational and rotational equations of motion. The hydrodynamic drag and torque, shear-induced lift, and gravitational force were included in the analysis. One-way coupling was assumed, and an in-house User Defined Function (UDF) was developed and was implemented into the ANSYS-FLUENT code for analyzing the fiber transport and deposition. The airflow field, the particle deposition efficiency, particle deposition pattern, and single-particle trajectories of fiber and sphere were analyzed and presented. The simulation results were compared with available experimental data and simulation results in the literature.
Impact of Urban Microclimate on Air Conditioning Energy Consumption Using Different Convective Heat Transfer Coefficient Correlations Available in Building Energy Simulation Tools
Authors: Kadam Sambhaji T. , Hassan Ibrahim , Wang Liangzhu (Leon) , Rahman Mohammad Azizur
Published: October 2021

Rapid urbanization resulted in the drastic expansion of the built infrastructure in urban areas. This eventually led to an increase in energy consumption in the residential and commercial sectors. An appropriate selection of the convective heat transfer coefficient correlation at the design stage is of vital importance as it directly affects the cooling load of the building and consequently buildings’ energy demand. In this context, the comparative analysis of existing convective heat transfer coefficient correlations (CHTCs) used in building simulation programs such as EnergyPlus, ESP-r, IES, IDA, and TAS, are assessed. These correlations are tested against the data of Liu et al.’s [1]. It is observed that some of CHTCs correlations show lower error and others exhibit a significant deviation. In the case of the CHTCs used EnergyPlus, it is observed that the TARP algorithm shows overall better prediction ability for windward, leeward, and roof surface. On the other hand, in the case of the ESP-r, different correlations show a good prediction ability for different surfaces. For windward surface: MoWiTT; for leeward surface: MoWiTT and McAdams; and for roof surface: Liu and Harris show closer prediction with an error of less than 30% among other correlations. The correlation used in IES, IDA, and TAS shows a large deviation for windward, leeward, and roof surfaces under considered input. Based on this analysis, it can be concluded that the choice of such CHTCs uses in the BES tool can lead to the significantly higher energy consumption of the building and hence need the expertise to make the appropriate selection.
Fluid Dynamics and Contact Stress on Hard Sealing Surface Analysis of LNG Cryogenic Ball Valve
Authors: Lin Zhen-Hao , Lu Jia-Jie , Li Jun-Ye , Qian Jin-Yuan
Published: October 2021

LNG (liquefied natural gas) cryogenic ball valve (CBV) is an important flow control device in LNG receiving stations. Its reliability directly affects the stability of the pipeline system, especially its damage or leak in the seat seal will seriously threaten the normal operation and the safety of LNG receiving stations. When LNG flows through the CBV, due to the interaction between fluid pressure and the valve structure, the hard sealing at the valve seat is not only subjected to the pre-tightening force of saucer spring, but also affected by the fluid pressure of the complex flow. Therefore, it is necessary to study the flow characteristics in the CBV and the hard sealing performance affected by the LNG. In this paper, the fluid dynamics and the contact stress on hard sealing performance in the CBV are analyzed. The pressure drop, pressure, and velocity distributions were analyzed, respectively. The contact stress on the hard sealing surfaces of the CBV with fluid pressure was analyzed by the fluid-structure coupling method. This work has a certain reference value for researching and mastering the hard sealing performance of cryogenic ball valves.