bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictive Value of Global Longitudinal Strain Imaging in Detecting Significant Coronary Artery Disease in Patients with Non-ST-segment Elevation Myocardial Infarction
Authors: Prasad Ravi Vishnu , Manikrao Gutte Rahul , Singh B. P. , Kumar Nirav , Kumar Goutam , Chandan Chandra Bhanu
Published: June 2023

Background:

Two-dimensional speckle-tracking echocardiography (2D-STE) is a newer method for assessing left ventricular (LV) systolic function. The aim of this study was to assess the predictive value of 2D global longitudinal strain (GLS) in the detection of longitudinal LV systolic dysfunction and the identification of significant coronary artery disease (CAD) in non-ST-segment elevation myocardial infarction (NSTEMI) patients without wall motion abnormalities.

Materials and Methods:

We enrolled 100 patients who were suspected cases of NSTEMI with echocardiography showing LV ejection fraction >50% and no regional wall motion abnormality. LV myocardial function was assessed using conventional echocardiographic measurements and myocardial deformation analysis with 2D-STE. The patients found to have significant CAD on coronary angiography were included in the cases group and those without significant CAD were considered as controls.

Results:

Mean age of the patients was 58.36 ± 11.21 years versus 56.54 ± 8.10 years in controls. Male preponderance was found in both case and control groups, with 66% (n = 33) and 56% (n = 28) males, respectively. The patients had significantly lower GLS as compared to the controls (-16.31 ± 1.34% vs -19.17 ± 1.63%, P < 0.001). The patients with positive troponin assay had a lower mean GLS −16.49 ± 1.5% as compared to those with negative troponin assay (−19.32 ± 1.54%, P < 0.001). Multivariate analyses indicated that GLS was an independent predictor of CAD in those with NSTEMI (GLS odds ratio = 0.024, P < 0.001).

Conclusions:

The present study demonstrates that 2D-STE is superior to conventional echocardiography in excluding significant CAD. It is a promising, easy to perform, bedside tool for diagnosis and prognostication in patients with NSTEMI. GLS has a potential to be used in conjugation with other risk stratification strategies to identify patients at high risk.
Left Ventricular Noncompaction Associated with Mitral Valve Prolapse and Severe Mitral Regurgitation
Authors: Sathyamurthy Immaneni , Subramanian Sasikala , Kirubakaran K. , Vijayashankar S.
Published: June 2023

Left ventricular non compaction (LVNC) cardiomyopathy is rare. Associated valvular lesions are still remote and they can complicate the underlying myocardial dysfunction. Echocardiographic diagnosis is well established. We are reporting a case of LVNC who presented with class III NYHA due to mitral valve prolapse with severe mitral regurgitation and severe LV dysfunction who was successfully operated and found asymptomatic with near normal LV function during 18 months follow up. This report is to stress that surgical management is feasible when indicated in cases of LVNC with acceptable outcomes.
Effects of Graded Doses of Sildenafil Citrate on Liver Microanatomy in Male Albino Rats
Authors: Bashir Sameena , Bhat Ghulam Mohammad , Khanday Shabir Ahmad , Wani Lateef Ahmad
Published: June 2023

Background:

Sildenafil citrate (SC) is a vasoerectile drug used to treat impotence caused by erectile dysfunction by inhibiting phosphodiesterase type 5 enzyme. The drug is widely used and may have adverse effects on the liver as it is metabolized mainly in the liver. Therefore, the present research aimed to study the effect of graded doses of SC on the histological structure of the liver in albino rats.

Methodology:

The present prospective interventional experimental study was conducted on 30 albino rats. The rats were given SC in different doses and for different periods. Rats were sacrificed, and the liver was extracted and processed for histopathological examination. The slides were stained with hematoxylin and eosin and observed under a compound light microscope.

Results:

SC administrated in graded doses in male albino rats caused central venous congestion, sinusoidal dilatation, and fatty infiltration in the liver. These changes were more pronounced in rats that received the drug in higher doses and for a longer duration. The effects of SC on the rat liver microanatomy were dose and time dependent.

Conclusion:

SC is relatively safe in low doses, but at higher doses and longer duration, there can be adverse effects on the liver.
Early Clinical Exposure – Effectiveness and Attitude among MBBS Students
Authors: Mathew Dini , Kantha B. M. Lakshmi , Dhanasekar P. Durai
Published: June 2023

Background:

In the traditional method, students learn theory without contacting patients in the initial part of MBBS. Early clinical exposure creates a scope for students to correlate basic science and clinical application. Hence, there is a need to study the effectiveness of different forms of early clinical exposure (ECE). The objectives of the study were to compare the knowledge acquired and attitude toward ECE by the students after different forms of ECE.

Methodology:

An observational study was done with 1st-year MBBS (n = 150) students. Based on the National Medical Council (Then Medical Council of India) II ECE document for undergraduate medical education programs, 10 topics were selected. The first six ECE sessions were conducted in the classroom, the next two at the hospital, and the last two virtually. Phase-validated structured multiple-choice questions (MCQs) and feedback were given to students before and after every ECE. The MCQ scores and feedback conducted in three forms were statistically analyzed.

Results:

There was a notable disparity in the mean between pre- and posttest. The mean scores of the virtual mode were better than the other two forms. As per the feedback analysis, most of the students observed ECE aid to clear conceptualization, critical thinking, and correlate anatomical basis in clinical cases. However, students also felt that it is too early to understand the topic in such detail in 1st year.

Conclusion:

This longitudinal study on ECE showed there is an increase in the knowledge and analytical skills of students. Hence, we recommend continuing ECE and to have a blended learning environment along with limited content to be included for a better outcome.
A study of antenatal, intranatal, and postnatal care of mothers in index pregnancy
Authors: Srivastava Shubhangi , Agarwal Monika , Nawaz Zaidi Syed Hasan , Agrawal Deepika
Published: June 2023

Background:

Most newborn deaths are preventable by improving quality of care during antenatal period and at delivery. Optimum maternal healthcare utilization, such as antenatal care (ANC) visits, skilled birth attendants or intranatal care, and postnatal care (PNC) services are associated with maternal health outcomes.

Objectives:

To study antenatal, intranatal, and PNC of mothers in index pregnancy.

Materials and Methods:

A descriptive cross sectional study was carried out among mothers of 360 neonates. Study was conducted in three government Sick newborn care units (SNCUs) of Lucknow district, which were randomly selected. The schedule was pretested on 10% of the total sample of mothers of neonates admitted to SNCU in Lok Bandhu Shri Raj Narayan Combined Hospital, Lucknow, to see for the accuracy of responses and to estimate the time needed. Three days a week were selected randomly for data collection. These 3 days were randomly allocated to collect data from three different SNCUs. One day was dedicated to collect data from one SNCU.

Results:

95.8% mothers had at least one ANC checkup during index pregnancy. Majority (62%) of the mothers had more than 4 ANC visits during index pregnancy. Majority (69%) of mothers had their first ANC checkup in 1st trimester, 25.8% in 2nd trimester, only 5.2% had their first ANC checkup in 3rd trimester. Only 28.3% mothers received counseling on newborn care during index pregnancy. Majority (92.5%) of the deliveries were attended by doctor. It was seen that 72.8% mothers got counseling on newborn care in postnatal period.

Conclusion: Extra efforts are needed to sensitize ASHA to counsel women regarding early registration, birth preparedness, adequate ANC, safe delivery, PNC, immunization of children etc and to mobilize the community and facilitate them in accessing these services.
Pica in various psychiatric disorders
Authors: Biswas Debalina , Brar Tabish , Beniwal Amit , Jamwal Aman Singh , Saran Brijesh , Seth Amoolya K.
Published: June 2023

Pica is the prolonged, compulsive consumption of inedible objects. Pica is sometimes attributed to an iron deficiency, and it gets better with iron supplements. Typical kind of pica is geophagy or eating clay. Apart from nutritional deficiencies, it is also seen in psychiatric disorders such as obsessive–compulsive disorder. Pica is thought to be a rare, autonomous, and separate habit in the context of schizophrenia, which is frequently ignored in the diagnosis and may lead to consequences such as intestinal obstruction, electrolyte imbalances, and heavy metal toxicity. Here, we are going to discuss a case of a 25-year-old female. She came with complaints of pain abdomen and undergone routine X-ray abdomen which showed ingested three nails. She was admitted under general surgery care. After the evacuation of nails, she undergone psychiatric evaluation. She has faint memory of nail ingestion but discussed stressful interpersonal relationship with her husband and managed on antidepressant medication. Her pica was probably due to interpersonal conflict with her husband few days ago. Her anxiety and sadness improved significantly with the tablet escitalopram and etizolam. In this case, we are trying to understand the psychopathology of pica, other than medical and known psychiatric causes.
Massive mediastinal lymphadenopathy in an adolescent male
Authors: Singh Prekshy , Mahendran C. S. , Sharma Manish Kumar
Published: June 2023

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), a burgeoning global health concern, is one of the top ten causes of mortality, affecting 10.6 million people; the vast majority of them were in South-East Asia and Sub-Saharan Africa. The etiology of mediastinal lymphadenopathy may be either benign or malignant. In adults, mediastinal lymphadenopathy due to TB may be a solitary finding or associated with pulmonary parenchymal lesions. Typical clinical manifestations such as fever, loss of appetite, and weight may not be present. Herein, we present a case of a 17-year-old male diagnosed with disseminated TB with a massive mediastinal lymph nodal.
Dietary pattern in brochial asthma control
Authors: Chandra Eshutosh , Mahendran C. S. , Das Pooja , Pandey Ankit , Saini Mukul
Published: June 2023

Background:

Asthma is a noncurable but preventable disease, responsible for higher morbidity worldwide. Approximately, in every fifth asthmatic patient, the possible role of food allergy should be taken into account.

Materials and Methods:

This was a descriptive study of dietary pattern in asthma control in 1 year, between 2021 and 2022 with 100 asthma and 100 healthy controls. Asthma was diagnosed as per Global Initiative for Asthma 2021. The control group had no respiratory ailments in their entire life span. Diabetes and hypertension were excluded from the study. Dietary habits were documented in both groups in a food diary, and five parameters were given thrust in order to simplify the study.

Results:

There is a positive correlation between consumption of fast food, packed chips, carbonated drinks and worsening of asthma in 36 patients. Low consumption of cereals has a positive correlation with asthma severity in 38 patients and greater than three times a week sugar intake associated with poor asthma control which is found in 26 patients.

Conclusion:

The correlation between asthma and the consumption of fast food, salted snacks, fried snacks, fats and oils nuts, dry fruits, and carbonated drinks has been observed in India. Consequently, it becomes crucial to lower the intake of these items and enhance public awareness regarding the impact of fast food on asthma through the implementation of effective public health policies.
Knowledge, attitudes, and practices in transport workers and gym-goers toward COVID-19
Authors: Das Pooja , Singh Prekshy , Dhandayuthapani Sivanesan , Tomo Sojit , Mahendran C. S.
Published: June 2023

Background:

Researchers in the field of public health frequently employ knowledge, attitude, and practice models to examine individuals' health-related behaviors. Hence, the primary objective of this study was to investigate the correlations between two groups with different sociodemographic status toward COVID-19 knowledge, affective attitudes, and preventive behaviors.

Method:

A cross-sectional comparative offline survey was conducted through questionnaire in a total of 166 population in and around Ghaziabad where 93 were active gym-goers and 73 were transport worker. Data collection was done from January to March 2022 that was included in statistical data analysis.

Results:

The difference of knowledge and practice was found when both groups were compared which was statically significant.

Conclusion:

The presence of sufficient COVID-19 knowledge demonstrates a direct association with increased engagement in precautionary behaviors. However, attitudes toward COVID-19 did not appear to have a significant role in motivating individuals to adopt preventive behaviors. Furthermore, COVID-appropriate behavior was associated with more educated and health-conscious groups.
Giant pedunculated angiomyofibroblastoma in young
Authors: Gulati Priyanka , Kumar Tyagi Mayurika Subodh , Singh Swati , Tomar Shilpa
Published: June 2023

Angiomyofibroblastoma (AMF) is an uncommon benign mesenchymal tumor that primarily affects women's vulvovaginal tissue but can sporadically affect male inguinoscrotal tissue. It is a well-circumscribed lesion that typically does not become a pedunculated hanging mass and is frequently believed clinically to be a Bartholin's gland cyst. A very few cases of vulvar AMF with pedunculated mass have been reported in the literature, and all cases involve the labia majora and middle-aged women. Here, we describe a case of a 22-year-old woman who experienced pedunculated mass in vulva involving the left labia majora. The differential diagnosis for the pedunculated vulvar mass in this young woman with a labial lesion was pedunculated AMF after excluding the most frequent illnesses.
Utility of bone turnover markers in metabolic bone diseases
Authors: Aggarwal Juhi , Modi Mansi , Gupta Raj Narayan , Pasha Eram Hussain
Published: June 2023

Bone turnover markers (BTMs) are biochemical indicators that provide information about the rate of bone remodeling, which involves the continuous process of bone formation and bone resorption. BTMs are measured in blood or urine samples and are used in the diagnosis, monitoring, and management of various metabolic bone diseases. They aid in the diagnosis of metabolic bone diseases by providing information about the bone turnover status. Abnormal levels of BTMs can indicate increased bone resorption or decreased bone formation, which are characteristic of certain conditions such as osteoporosis, osteomalacia, or Paget's disease. BTMs can provide insights into the severity of metabolic bone diseases. For example, in osteoporosis, elevated levels of bone resorption markers such as C-terminal telopeptide of type I collagen (CTX) or tartrate-resistant acid phosphatase 5b (TRACP-5b) indicate increased bone breakdown and higher fracture risk. Similarly, low levels of bone formation markers like procollagen type I N-terminal propeptide (PINP) or osteocalcin can indicate reduced bone formation and decreased bone strength. BTMs are valuable tools for assessing the response to treatment in metabolic bone diseases. Changes in BTM levels over time can indicate the effectiveness of interventions such as pharmacotherapy, lifestyle modifications, or surgical interventions. Decreased levels of bone resorption markers or increased levels of bone formation markers suggest a positive response to treatment, whereas persistent abnormal BTM levels may indicate the need for treatment adjustment. It's important to note that BTMs should be interpreted in conjunction with other clinical factors and imaging studies. They provide valuable information about bone turnover dynamics but should not be relied upon as standalone diagnostic or prognostic tools.
IMPACT: Numerical Study of Aerodynamics of an Iced Forward-Swept Tail with Leading Edge Extension
Authors: Page James , Ozcer Isik , Zanon Alessandro , De Gennaro Michele
Published: June 2023

In-flight icing significantly influences the design of large passenger aircraft. Relevant aspects include sizing of the main aerodynamic surfaces, provision of anti-icing systems, and setting of operational restrictions. Empennages of large passenger aircraft are particularly affected due to the small leading edge radius, and the requirement to generate considerable lift for round out and flare, following an extended period of descent often in icing conditions. This paper describes a CFD-based investigation of the effects of sweep on the aerodynamic performance of a novel forward-swept horizontal stabilizer concept in icing conditions. The concept features an unconventional forward sweep, combined with a high lift leading edge extension (LEX) located within a fuselage induced droplet shadow zone, providing passive protection from icing. In-flight ice accretion was calculated, using Ansys FENSAP-ICE, on 10°, 15° and 20° (low, intermediate, and high) sweep horizontal stabilizers, with the tail as attached to the full-scale aircraft, for a 45-minute holding pattern. The aerodynamic analyses of the iced tails were carried out using Ansys Fluent Aero with angle of attacks from 0° to -15°. All three sweeps show reduction in lifting performance under icing conditions, due to early separation. However, comparisons of lift coefficient versus angle of attack (CL-α) curves, spanwise lift distributions, and three-dimensional flow fields show that increasing sweep reduces the early separation tendency along the span, but also reduces LEX lifting performance. This leads overall to reduced icing associated lift degradation at higher sweep. This effort has been undertaken as part of the Cleansky 2 IMPACT project (GA no. 885052).
Snow Effects on the NGCTR Nacelle for Relevant Certification Conditions
Authors: Kool Nina , Van der Weide Edwin , Spek Ferdinand , van der Ven Harmen , van 't Hoff Stefan
Published: June 2023

This paper is focused on the numerical analysis of the impingement and water catch rate of snow particles on the engine air intake of the Next Generation Civil Tilt Rotor (NGCTR). This NGCTR is developed by Leonardo Helicopters. The collection efficiency and water catch rate for the intake geometry are obtained for the test cases that have been defined for the relevant snow conditions. These conditions are related to the flight envelope of the NGCTR, existing EASA/FAA certification specifications, and the snow characterization. The analyses have been performed for the baseline air intake geometry. A range of particle diameters has been simulated with a particle density equal to the density of ice and with a particle drag relation that disregards the particle shape. Based on the results for the water catch rate on the basic nacelle configuration in snow conditions it is concluded that the ‘cheeks’ of the duct are more susceptible to impingement of larger snow crystals (>75 μm), whereas the ‘chin’ of the duct is more susceptible to impingement of smaller droplets (<75 μm). Additionally, ground operations of the NGCTR are predicted not to be critical for icing by snow crystals primarily due to the perpendicular orientation of the intake plane to the rotor downwash. The assessment of the basic configuration of the NGCTR inlet in snow conditions has shown that the critical area of snow impact exists near the small passage inside the inlet where the duct transitions towards a circular shape.
UAV Icing: Icing Cases for Validation of Path Planning Method
Authors: Cheung Michael , Hann Richard , Johansen Tor
Published: June 2023

As part of the complete solution to deal with atmospheric in-flight icing on unmanned aerial vehicles (UAV), a path planner is a valuable tool for finding an optimal path for accomplishing UAV missions. When considering icing conditions, the planner manages areas with icing risk. Together with an electro-thermal ice protection system (IPS), the path planner can optimize energy consumption by comparing energy consumed flying through the cloud or around it, as the UAV can now more safely pass through the ice. The UAV’s aerodynamic stability is also considered by meeting lift requirements, producing enough thrust, and having battery capacity left. These are constraints in the planner to ensure that the UAV can complete its mission. Benchmark icing cases are constructed to validate that the path planner performs as intended. A particle swarm optimization (PSO) is used as a method in the planner due to its ability to handle highly nonlinear problems and to be able to explore the solution space effectively. Weather conditions are chosen following Federal Aviation Administration 14 CFR Part 25 Appendix C icing design envelopes required for certification. A cloud with ice is designed within a defined mission area. The constructed cloud will change size between simulations, where, by a specific cloud size, the PSO predicts that less energy is consumed flying through the iced area with an IPS than flying around it. With these icing cases, a baseline is set for future validation. The work performed in this paper will be used to validate the PSO algorithm. This paper can also benefit any UAV users that require a robust path planner by using the icing cases to identify any inconsistencies in their code. The results show that one version of the PSO handles most of these icing cases well. Inconsistencies were identified when using these icing cases, but this study makes an excellent example of how they can be used.
UAV Icing: 3D Simulations of Propeller Icing Effects and Anti-Icing Heat Loads
Authors: Müller Nicolas Carlo , Hann Richard
Published: June 2023

In-flight atmospheric icing is a significant threat to the use of unmanned aerial vehicles (UAVs) in adverse weather. The propeller of the UAV is especially sensitive to icing conditions, as it accumulates ice at a faster rate than the wings of the UAVs. Ice protection systems can be developed to counteract the danger of icing on the propeller of UAVs. In this study, the influence of different meteorological conditions on a propeller of a UAV is analyzed for a UAV with a wingspan of a few meters. The ice accretion and the performance degradation and the required anti-icing heat fluxes have been calculated using numerical methods with ANSYS FENSAP-ICE. This analysis has been used to evaluate the critical conditions for the operation of a UAV in icing conditions and the design of a thermal IPS system for a propeller. The highest ice mass has been found at a temperature of −10 °C and an MVD of 20 μm in intermittent maximum icing conditions. The performance degradation has been the highest at lower temperatures of −15 °C in intermittent and at −5 °C in continuous maximum icing conditions. For the design of an IPS, the conditions at the lowest design temperature and the smallest median volumetric diameter (MVD) have been identified as critical points. The most important driver for the required IPS loads on the propeller is the outside temperature, followed by the liquid water content of the cloud. The MVD is important for the distribution of the liquid water content. Here, the highest heat flux required for anti-icing has been computed. The second critical design point is the highest temperature, at an MVD of 40 μm. At this condition, the heat flux is the lowest. This analysis is the basis for the development of electro-thermal IPS for use in UAVs. This paper expands previous research to cover the effect of icing on a propeller of a UAV in a wide range of icing conditions and explains the influence of those conditions on an IPS design.
Electro-Mechanical Resonant Ice Protection Systems: Numerical Prediction and Experimental Verification of the De-icing of a NACA 0024 Airfoil
Authors: Palanque Valerian , Pothin Jason , Budinger Marc , Pommier-Budinger Valérie , Yaich Ahmed
Published: June 2023

This paper proposes an extension to curved surfaces of a design method of piezoelectric ice protection systems established for planar surfaces. The method is based on a finite element analysis which enables the fast computation of the resonant modes of interest to de-ice surfaces as leading edges. The performance of the modes of interest is assessed according to their deicing capacity estimated from the electro-mechanical coupling between the electric charge of the piezoelectric actuators and the strain energy in the structure. The method is illustrated on a NACA 0024 airfoil. Several experimental tests are conducted in an icing wind tunnel to verify the numerical predictions of the ice shedding and the operation of the system.
Comparison of Numerical Simulations with Experimental Data for an Electrothermal Ice Protection System in Appendix O Conditions
Authors: Breitfuß Wolfgang , Moser Richard , Hassler Wolfgang , Ferschitz Hermann , Neubauer Thomas , Puffing Reinhard , Diebald Stefan , Schweighart Simon
Published: June 2023

This paper provides information on the comparison of numerical simulations with experimental data for an electrothermal ice protection system with a focus on Appendix O [1] Freezing Drizzle (FZDZ) and Freezing Rain (FZRA) conditions. The experimental data is based on a test campaign with a 2D NACA23012 wing section in the RTA Icing Wind Tunnel in Vienna. 22 icing runs (all either unheated or in anti-ice mode) were performed in total and all residual ice shapes were documented by means of high-resolution 3D scanning. Unheated FZDZ and FZRA reference as well as heated cases with different heater configurations are presented. The experimental results are compared to numerical predictions from two different icing codes from AeroTex GmbH (ATX) and the University of Applied Sciences FH JOANNEUM (FHJ) in Graz. The current capabilities of the codes were assessed in detail and regions for improvement were identified. Overall, the codes were able to predict the ice shapes of both the unheated and heated cases with reasonable accuracy but both codes overestimated the thickness of the runback ice ridges throughout all cases. The biggest deviations in terms of the position of the ice accretions were seen on the lower surface; on the upper surface a better match was observed.
Development of a Robust Surface Ply for Pneumatic Deicers
Authors: Taylor Andrew , Slane Casey , Hu Jin , Botura Galdemir
Published: June 2023

The purpose of this paper to is to review the methodology applied by Collins Aerospace to develop, test and qualify a more robust surface ply rubber compound that has demonstrable improvements in durability and performance at sub-freezing temperatures. Using in-service products as a reference, pneumatic deicers in use on regional turboprop applications were selected as a basis for operational characteristics and observed failure modes. Custom test campaigns were developed by Collins to comparatively evaluate key characteristics of the surface ply material including low temperature elasticity, erosion durability, and fluid susceptibility. Collins’ proprietary engineered rubber formulations were individually evaluated and built into fully functional test deicers for component level testing to DO-160G environmental exposure, comparative ice shed performance in Collins’ Icing Wind Tunnel and erosion in Collins’ Rain Erosion Silo.
Passive Ice Protection Systems Lab Scale Testing Methodology
Authors: García Paloma , Mora Julio , Carreño Francisco , Redondo Francisco , Rodriguez Rafael , Rivero Pedro , Vicente Adrian , Acosta Carolina , Larumbe Silvia , Medrano Ángel , Lecumberri Cristina
Published: June 2023

Aircraft icing is a well-known problem that can have serious consequences for flight safety. To combat this problem, various ice protection systems (IPSs) have been developed and are currently used on most aircraft, including thermal ice protection systems. However, these systems can be costly, heavy and ineffective. Therefore, there is a need to improve the efficiency and response time of these systems. In recent years, research has focused on the development of hybrid systems that combine different ice protection technologies to achieve better performance.

In this sense, the use of an active element with a coating on its external part that improve its efficiency would be an important advance, but there is a wide range of active systems and even more of coatings and surface treatments. Therefore it would be helpful to have a test methodology that would allow a simple but thorough assessment of the performance of each passive system, and this is precisely what is proposed in this publication.

In order to decouple the behavior of the active system from the coating and to be able to evaluate the latter independently, a characterization sequence of passive systems has been developed considering different potential application areas and different icing conditions.

A novel aspect of this methodology is that the specimens were tested alongside an identical thermoelectric system used as reference that did not interfere with the coating. This allowed for the evaluation of the materials' properties with and without any application of energy.

The simple geometry of the specimens makes these tests feasible for coating techniques that do not accept complicated shapes. The aim of this methodology is to provide an accessible first evaluation of the materials in their use as IPSs. In addition, the test matrix allows the identification of the most appropriate applications for each of the passive system strategies studied.

Some results of the materials tested in the project in which this work was carried out are shown to illustrate the potential usefulness of the methodology.
Aluminum Sample Characterization on the NRC AIWT Ice Adhesion Spin Rig
Authors: Clark Catherine
Published: June 2023

This paper presents the adhesion strength of ice on sanded and machine-finished aluminum test coupons as measured using the National Research Council of Canada (NRC) Altitude Icing Wind Tunnel (AIWT) spin rig. This rig is used to evaluate commercial and internally-developed coatings for low-adhesion properties, and the performance of ice on aluminum is required as a baseline to compare the coatings against. The tests are performed over a range of aerodynamic and icing cloud conditions, including variations in static air temperature and exposure time (and therefore accumulated ice mass). The data analysis includes an evaluation of the uncertainty in the results based on the measured ice mass repeatability and the measured shear stress repeatability. The results show the adhesive shear stress of ice, generated with a 20 μm icing cloud at a true airspeed of 80 m/s and a static air temperature of -20°C to create rime ice conditions, is 682 kPa (±13%) for aluminum coupons with a sanded finish and 579 kPa (±16%) for aluminum coupons with a machined finish. The results are comparable to those found in literature for aluminum samples tested using centrifugal methods. There was no observed trend in the adhesive shear stress with variations in temperature or ice mass, within the range of conditions tested.
Development of an Icing Test Facility for Rotors and Propellers of Remotely Piloted Aircraft Systems (RPAS)
Authors: Orchard David
Published: June 2023

The development and calibration of a new facility to test medium size rotors for Remotely Piloted Aircraft Systems (RPAS) under in-flight icing conditions is described. This facility has made use of a 3 m x 6 m cold room available at the NRC which includes a spray system to provide the icing cloud as well as a dedicated rotor stand assembly that incorporates a load cell and dynamometer. Calibration data of the spray drop sizes and liquid water content are provided and compared to conditions of the natural environment as detailed in icing regulations for transport category airplanes, i.e., CFR 14 Part 25 Appendix C and O. Data to examine the sensitivity of rotor performance, under a constant liquid water content to various droplet sizes are provided for a medium sized rotor. Tests have also been performed that examine the ability of the rotor to maintain predefined thrust, torque and power performance throughout an icing encounter of fixed duration. For the purposes of this study, the rotor performance is determined by considering a hypothetical quadcopter RPAS concept with a baseline vehicle weight (15 kg), and a minimum operation time (122 seconds) during which rotor performance, and hence controlled flight, must be maintained.
High Resolution Cloud Particle Imaging Incorporating State-of-the-Art Digital Cameras with Pulsed LED Illumination
Authors: Bachalo William Don
Published: June 2023

Super-cooled large drops present serious threats to aviation safety and as a result, the problem has been addressed by the FAA with the additional icing certification requirement. SLD clouds often consist of bi-modal drop size spectra leading to great challenges when it comes to simulating and characterizing these conditions in situ and in icing wind tunnels. Legacy instrumentation for measuring drop size distributions and liquid water content has been challenged under these conditions. In this report, a high-resolution particle imaging instrument is described; this instrument addresses the need for measuring drop size distributions and liquid water content over a wide range of drop sizes (10 to 2500 μm or larger). A high-throughput megapixel digital camera is used to record shadow images of the particles. High-quality illumination of the particle field is provided with high-power LED illumination with driving electronics designed to provide pulse durations as short as 25ns with sufficient fluence. Image processing software has been developed to enable automated setup of the instrument, image acquisition and processing, and efficient storage of the particle images. Calibration methods regarding the dependence of the depth-of-field to drop size were developed to enable sampling statistics bias corrections due to variations in the sample volume. Measurements acquired in the NASA Icing Research Tunnel (IRT) are provided as an example of the measurement capabilities of the newly developed instruments.
Comparability of Hot-Wire Estimates of Liquid Water Content in SLD Conditions
Authors: Esposito Biagio M. , Orchard David , Lucke Johannes , Nichman Leonid , Bliankinshtein Natalia , Lilie Lyle , Catalano Pietro , D'Aniello Francesco , Strapp J. Walter
Published: June 2023

Future compliance to FAA 14 CFR Part 25 and EASA CS-25 Appendix O conditions has required icing wind tunnels to expand their cloud simulation envelope, and demonstrate accurate calibration of liquid water content and droplet particle size distributions under these conditions. This has led to a renewed community interest in the accuracy of these calibrations, and the potential inter-facility bias due to the choice of instrumentation and processing methods. This article provides a comparison of the response of various hot-wire liquid water content instruments under Appendix C and supercooled large droplet conditions, after an independent similar analysis at other wind tunnel facilities. The instruments are being used, or are under consideration for use, by facilities collaborating in the ICE GENESIS program. For droplet median volume diameters (MVDs) between about 15 and 250 μm, cylindrical hot wire LWC sensors were found to consistently and increasingly under-read measurements from conical and trough TWC sensors as MVD increased, and were not considered further. Of the remaining TWC sensors, the specific instruments investigated were found to agree within about ± 20% of their average test point response for the range of conditions tested, but systematic scale differences between instruments were found to reach about a factor of 1.4. Sensitivity to increasing droplet MVD was concluded to be similar amongst different instruments given the uncertainties, except for two that exhibited notable roll-off with MVD relative to the others.
Liquid Water Content Instrumentation Study at the NRC AIWT
Authors: Clark Catherine , Orchard David
Published: June 2023

The National Research Council Altitude Icing Wind Tunnel liquid water content calibrations have historically relied on a 2.4 mm diameter rotating cylinder for drop sizes up to 50 μm and a 6.2 mm diameter rotating cylinder for drop sizes from 50 μm to 200 μm. This study compares the facility calibration, derived from rotating cylinder measurements, to water content measurements from the Science Engineering Associates Multi-Element Probe and the National Research Council Compact Iso-Kinetic Probe over a range of airspeeds and drop sizes. The data show where the rotating cylinder measurements may start to underestimate the liquid water content (LWC), possibly due to splashing at higher airspeeds and drop sizes. The data also show that the LWC read by the Multi-Element Probe is higher than that provided by the rotating cylinders, and the Compact Iso-Kinetic Probe (CIKP) reads higher than both other methods. These trends are consistent with instrumentation comparison data from other icing wind tunnels. The study examines the effects of aerodynamic blockage on the probe measurements and the effects of placing the CIKP reference humidity sensor at different positions relative to the icing cloud. Overall, the data do not support changing the AIWT LWC calibration method from the rotating cylinder at this time.
Development of an Altitude Evaporation Model for Icing Tunnel Control
Authors: Davison Craig
Published: June 2023

In 2017 the National Research Council of Canada developed an evaporation model for controlling engine icing tunnels in real time. The model included simplifications to allow it to update the control system once per second, including the assumption of sea level pressure in some calculations. Recently the engine icing system was required in an altitude facility requiring operation down to static temperatures of -40°C, and up to an altitude of 9.1 km (30 kft) or 30 kPa. To accommodate the larger temperature and pressure range the model was modified by removing the assumption of sea level operation and expanding the temperature range. In addition, due to the higher concentration of water vapor that can be held by the atmosphere at lower pressures, the significance of the effect of humidity on the air properties and the effect on the model was investigated. The effect of humidity on the density, specific heat, viscosity, thermal conductivity and Prandtl number of air compared to assuming dry air was examined. The effect of humidity on the individual thermodynamic and transport properties could be significant but the overall effect on the liquid water content calculated by the model to be delivered to the engine was not. The error in using the property correlations from the original model over the expanded temperature range was found to be minimal. Finally, the numerical technique was modified to decrease the solution time under extreme operating conditions. This modification increased the solution time in some standard conditions but still kept it within the required time. The new model was compared to the previous model under sea level conditions and found to give practically the same results within the expected error allowed by the solver.
Optical Ice Detector: Measurement Comparison to Research Probes
Authors: Anderson Kaare , Ray Mark , Jackson Darren
Published: June 2023

The Collins Aerospace Optical Ice Detector is a short-range polarimetric cloud lidar designed to detect and discriminate among all types of icing conditions with the use of a single sensor. Recent flight tests of the Optical Ice Detector (OID) aboard a fully instrumented atmospheric research aircraft have allowed comparisons of measurements made by the OID with those of standard cloud research probes. The tests included some icing conditions appropriate to the most recent updates to the icing regulations. Cloud detection, discrimination of mixed phase, and quantification of cloud liquid water content for a cloud within the realm of Appendix C were all demonstrated. The duration of the tests (eight hours total) has allowed the compilation of data from the OID and cloud probes for a more comprehensive comparison. The OID measurements and those of the research probes agree favorably given the uncertainties inherent in these instruments.
Minimum Operational Performance Standards for Weather Radar Ice Crystal Detection Function
Authors: Lukas Jan , Zhang Rockee , Starzec Mariusz , Finley Jeff , Sishtla Venkata , Lakhi Divesh , Gidner Dawn , Berthier Jean-Baptiste
Published: June 2023

The RTCA SC-230 committee began working on minimum operational performance standards (MOPS) for ice crystal detection using weather radar in 2018. The resulting MOPS document will be released in 2023. This paper presents the rationale, summarizes key requirements, and discusses means of validation for an ice crystal detection function incorporated in an airborne weather radar system.
3 Inch Ice Shapes, AB Initio
Authors: Leopold Dave , Malone Adam , Bosetti Cris , Macomber John , Slim Rami
Published: June 2023

The term “3 inch ice shapes” has assumed numerous definitions throughout the years. At times it has been used to generally characterize large glaze ice accretions on the major aerodynamic surfaces (wing, horizontal stabilizer, vertical stabilizer) for evaluating aerodynamic performance and handling qualities after a prolonged icing encounter. It has also been used as a more direct criterion while determining or enforcing sectional ice shape characteristics such as the maximum pinnacle height. It is the authors’ observation that over the years, the interpretation and application of this term has evolved and is now broadly misunderstood. Compounding the situation is, at present, a seemingly contradictory set of guidance among (and even within) the various international regulatory agencies resulting in an ambiguous set of expectations for design and certification specialists. The focus of this paper is to provide a more complete and accurate historical accounting of “3 inch ice shapes” which is currently only speculative and incomplete within the public purview. It is the authors’ intent to provide a better collective understanding and appreciation for how the industry arrived at this current state.
An Analytical Method for Prediction of High Altitude Total Water Exposure for In-Service Long Range Aircraft
Authors: Sanford Jerome , Bravin Melissa , Clarkson Matthew , Natsui Edward
Published: June 2023

To support an industry wide response to an EASA proposed Special Condition regarding the threat of in-flight supercooled liquid water icing conditions at altitudes above FL300, Boeing 777 fleet data were used to estimate the frequency and severity of such icing occurrences. The data were from the calendar year 2019 and included ~ 950,000 airline revenue flights from around the world by multiple operators. The unique architecture of the Primary Ice Detection System (PIDS) on that model, in addition to robust meteorological data that was able to be correlated, afforded an opportunity to conservatively estimate the Total Water Exposure (TWE) and thus the Liquid Water Content (LWC) of the icing encounters captured at FL295 and above. This paper will outline the key methods used and present the findings.
Cold Soaked Fuel Frost Roughness Evolution on a Simulated Integrated Fuel Tank with Aluminum Skins
Authors: McClain Stephen , O'Neal Dennis , Forslund Nicholas , Ahmed Salah Uddin
Published: June 2023

Cold soaked fuel frost (CSFF) is frost that forms on aircraft wing surfaces following a flight because of cold excess fuel remaining in integrated fuel tanks. Previous investigations by Zhang et al. (2021a) and Zhang et al. (2021b) have focused on experimental measurements and correlation development for frost observed using a small frost wind tunnel employing a thermo-electric cooler to impose a surface temperature for a range of environmental conditions. To model the CSFF approach in more detail, an experimental facility was developed and described by McClain et al. (2020) using a thermal model of an integrated wing fuel tank placed inside of a climatic chamber. In this paper, experimental measurements of CSFF are presented using two aluminum wing skins. One of the skins was created using an aluminum rib structure, and the other skin was created without the rib. An automated, photogrammetric approach was used to characterize the roughness evolution on each surface when exposed to a set of environmental conditions. The measurements were then used to explore the correlation of Zhang et al. (2021b) when considering the convection through the surrogate fuel fluid and the conduction through the aluminum skin. The correlations of Zhang et al. (2021b) capture the trends of the root-mean-square (RMS) roughness and the relative magnitudes of the RMS roughness when comparing the effect of different air temperatures on frost evolution. However, the sand-grain roughness predictions using the correlation of Zhang et al. (2021b) indicate that the present model implementation is underestimating the frost surface temperature generally leading to predictions of excessive equivalent sand-grain roughness values.
Impact Ice Adhesion at NASA Glenn: Current Experimental Methods and Supporting Measurements
Authors: Giuffre Christopher , Chen Ru-Ching
Published: June 2023

When examining the literature on the adhesion strength of impact ice, there have been a wide range of methodologies tried to measure the required stresses to induce interfacial delamination. Utilizing the Icing Research Tunnel at the NASA Glenn Research Center to generate the impact ice required for this work, several different mechanical tests have been and are being developed to determine the stresses along the interface between ice and coupon. This set of tests includes the technical mature modified lap joint test which has been used to conduct ice adhesion studies through a wide sweep of icing conditions. To conduct in situ ice adhesion measurements inside of the Icing Research Tunnel, several new experiments are currently being developed to make ice adhesion measurements during and immediately after ice accretion. In addition to these experimental methods, several supporting measurement techniques have been developed to allow for a better understanding on the influence of icing cloud conditions on the mechanical behavior of impact ice. Digital image correlation has been successfully implemented to augment the data generated by the modified lap joint test with full field surface displacement and strain measurements which allow for insight into the deformation processes present during a test. Both optical microscopy of impact ice samples along with ice replication techniques have been used to study the grain structure of the impact ice. This has led to a deeper understanding of the results from the modified lap joint method and how the structure of impact ice changes as it is accreted during an icing spray. The freezing process of impact ice generated by supercooled liquid water is not a volume conserving process, which leads to the presence of residual strains along the interface between ice and substrate. These strains have been observed using both a simplified flat geometry and a representative airfoil. The data gathered by these experimental adhesion methods and supporting measurements allows for a comprehensive understanding on the behavior of impact ice which will be critical to the development of future ice shedding models.