bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid response of nonstructural carbohydrate allocation and photosynthesis to short photoperiod, low temperature, or elevated CO2 in Pinus strobus
Authors: Chang Christine Y. , Unda Faride , Mansfield Shawn D. , Ensminger Ingo
Published: November 2023

During autumn, decreasing photoperiod and temperature temporarily perturb the balance between carbon uptake and carbon demand in overwintering plants, requiring coordinated adjustments in photosynthesis and carbon allocation to re‐establish homeostasis. Here we examined adjustments of photosynthesis and allocation of nonstructural carbohydrates (NSCs) following a sudden shift to short photoperiod, low temperature, and/or elevated CO2 in Pinus strobus seedlings. Seedlings were initially acclimated to 14 h photoperiod (22/15°C day/night) and ambient CO2 (400 ppm) or elevated CO2 (800 ppm). Seedlings were then shifted to 8 h photoperiod for one of three treatments: no temperature change at ambient CO2 (22/15°C, 400 ppm), low temperature at ambient CO2 (12/5°C, 400 ppm), or no temperature change at elevated CO2 (22/15°C, 800 ppm). Short photoperiod caused all seedlings to exhibit partial nighttime depletion of starch. Short photoperiod alone did not affect photosynthesis. Short photoperiod combined with low temperature caused hexose accumulation and repression of photosynthesis within 24 h, followed by a transient increase in nonphotochemical quenching (NPQ). Under long photoperiod, plants grown under elevated CO2 exhibited significantly higher NSCs and photosynthesis compared to ambient CO2 plants, but carbon uptake exceeded sink capacity, leading to elevated NPQ; carbon sink capacity was restored and NPQ relaxed within 24 h after shift to short photoperiod. Our findings indicate that P. strobus rapidly adjusts NSC allocation, not photosynthesis, to accommodate short photoperiod. However, the combination of short photoperiod and low temperature, or long photoperiod and elevated CO2 disrupts the balance between photosynthesis and carbon sink capacity, resulting in increased NPQ to alleviate excess energy.
The forms of climate action
Authors: Almeida Paul , González Márquez Luis Rubén , Fonsah Eliana
Published: November 2023

Scientific research on the mechanisms to address global warming and its consequences continues to proliferate in the context of an accelerating climate emergency. The concept of climate action includes multiple meanings, and several types of actors employ its use to manage the crisis. The term has evolved to incorporate many of the suggested strategies to combat global warming offered by international bodies, states, nongovernmental organizations, the private sector, and social movements. The present work offers a classification scheme to build a shared understanding of climate action through a lens of environmental justice and just transitions developed by sociologists and others. The classification system includes major institutional and noninstitutional forms of climate action. By identifying the primary forms of climate action, analysts, scholars, policymakers, and activists can better determine levels of success and how different forms of climate action may or may not complement one another in the search for equitable solutions in turning back the rapid heating of the planet.
Beyond ‘heightism’ and ‘height premium’: An anthropology and sociology of human stature
Authors: Lasco Gideon
Published: November 2023

This review article examines the meanings and materialities of human stature, from serving as a marker of human difference to shaping the socio‐spatial experiences of individuals. I introduce existing perspectives on height from various disciplines, including biomedical discourses on the factors (e.g. nutrition, genetics) that determine height, economic discourses on how the average heights of populations have changed over time, sociobiological and psychological discourses that assume a pre‐cultural, evolutionary “height premium”, and popular discourses on heightism and height discrimination. Drawing from a diverse range of scholarship since Saul Feldman called for a “sociology of stature” in the 1970s, I then present ways in which height and height differences have figured in various domains of human experience, from employment and education to sports and social relationships. Finally, I survey people's attempts to become taller or shorter, and the implicit values that inform such height‐making practices. What these figurations and practices show, I argue, is that height intersects with notions of race, class, gender, and beauty – but is irreducible to any of them, and is thus best viewed as a distinct, embodied form of distinction, difference, and inequality. I conclude by proposing a research agenda for future work.
Pragmatic Ambiguity, Implicatures, and Translation1
Authors: Francesch Pau , Payrató Lluís
Published: November 2023

The goal of this work is to put forward a pragmatic and translational framework for analysing target texts (TT) and source texts (ST) containing conversational implicatures that lead to pragmatic ambiguity. Ambiguity, sensu lato, is deemed to be related to indeterminacy and vagueness. Nevertheless, in the strict sense, ambiguity is understood as ‘more than a single processing instruction for a given utterance’. More specifically, pragmatic ambiguity arises whenever differences in cultural conventions between SL speakers and TL speakers lead to differences in the existence, meaning and salience of implicatures among ST and TT. Using real translation cases selected from a purpose‐built corpus containing fiction written and oral texts, we show which pragmatic ambiguities translators come across, and how translation techniques are used, either to maintain ambiguity or to select one intended processing instruction.
Traction suture fixation technique using a capsular tension ring fragment for severe lens displacement during cataract surgery in dogs
Authors: Fukumoto Shinya , Minamoto Tomomi
Published: November 2023

Objectives

To describe the traction suture fixation technique for severely displaced lenses (≥180°) using a capsular tension ring (CTR) fragment during cataract surgery in dogs, and to retrospectively investigate its clinical outcomes.

Animals Studied

Eight dogs (nine eyes).

Procedures

The medical records of dogs with severe lens displacement (≥180°) due to cataracts that underwent traction suture fixation during cataract surgery using a CTR fragment at the Grand Animal Hospital (Hyogo, Japan) between November 2019 and September 2022 were retrospectively reviewed. The retrieved data included the signalment, type of CTR, and postoperative outcomes.

Results

A single CTR fragment was used to fix the capsular bag to the sclera in six eyes, and two CTR fragments were used at two sites in three eyes. The lengths of the CTR fragments used were 1 one‐fifth fragment, 3 one‐fourth fragments, and 8 one‐third fragments. Postoperative complications included uveitis (nine eyes), glaucoma (one eye), posterior iris adhesion (one eye), corneal ulcer (one eye), and intracorneal stromal hemorrhage (one eye). Vision was maintained in all dogs during the follow‐up period (2 months to 2 years and 8 months) without recurrent capsular bag displacement.

Conclusions

This technique can correct and stabilize capsular bag displacement relatively easily through a small incision during cataract surgery in dogs with severe lens displacement. Intraocular lens implantation was also possible.
THE BEHAVIOR, STABILITY PROPERTIES, AND POTENTIAL APPLICATIONS OF RHAMNOLIPID BIOSURFACTANTS IN OIL DEGRADATION
Authors: Zainal Abidin Muhamad Hissammuddin Shah , Sakaria Nor Dina , Azman Nur Raudhah , Asli Umi Aisah
Published: November 2023

Rhamnolipid biosurfactants are among the most investigated for various applications, owing not only to their much lower environmental impact compared to chemical surfactants but also because they have proven effective in reducing surface tension and critical micelle concentration (CMC). However, there is concern regarding their high cost. This work aims to determine important behavior and properties of rhamnolipids and verify their potential for oil degradation. They were characterized using FTIR, 1H NMR, and 13C NMR spectroscopy to determine the main functional groups and the chemical structure of rhamnolipids for oil degreasing. Then, the influence of thermodynamic properties on CMC stability was studied to establish the stability behavior. This investigation is essential as good oil degreasing products require low CMC values to minimize the amount used during the oil removal process, form micelles, and solubilize dirt and oil. The oil degradation ability of rhamnolipids in different concentrations was studied using an oil dispersion test and the method of oil removal from a glass surface. Overall, this investigation proves that the temperature of the solution and immersion time influenced the CMC and surface tension value for the rhamnolipids. The lowest CMC value was 35 mg/L at 55 °C after 48 h of stabilization. The minimum recommended amount of rhamnolipids for the oil degrease formulation was also found to be 0.1% w/v, which is very low. This study showed that the behavior and stability of rhamnolipids are suitable for oil degradation applications and can efficiently replace chemical surfactants in oil degradation products.
AN ADAPTIVE KALMAN FILTERING ALGORITHM WITHOUT USING KINEMATIC MODELS
Authors: Wah Hnin Lae , Thant Sin Aung Myo
Published: November 2023

The performance and accuracy of Kalman filter depends on its gain value related to the process noise covariance and the measurement noise variance which may vary according to experimental settings such as noise and sampling time. Thus, setting the appropriate values for the noise variances that fit for a wide range of experimental setting is a challenge for conventional Kalman filter. This paper proposes an adaptive Kalman filter with the adaptive noise variance for velocity estimation without using kinematic model. By applying only the quantized position measurement signal generated from the optical incremental encoder, an adaptive process noise variance is proposed. The experimental results show that the proposed method outperforms the conventional Kalman filter in achieving accurate and smooth velocity estimation without large time delay.
ACOUSTICAL ANALYSIS FOR THE LECTURE ROOMS IN UNIMAP
Authors: Tan W. H. , Hafiz N. Muhammad , Chan C. K. , Niresh J.
Published: November 2023

Acoustic analysis is a measurement used to analyse the behaviour of sound waves in enclosed spaces, which influences speech intelligibility. Another parameter that influences speech intelligibility is reverberation time. Reverberation time is the time for the sound source to decay by 60 dB. A high reverberation time causes sound to dissipate more slowly, resulting in continual reflection of sound waves, which disrupts student concentration in class. Furthermore, a poor acoustic environment could have an impact on health and lecture delivery. The objective of this study is to determine and analyse the acoustic performance for five selected lecture rooms in UniMAP. The reverberation time is the parameter of this study that was obtained from the Root Mean Square (RMS) of the sound pressure by using the impulsive sound source method from a burst balloon. In this study, the "balloon pop" sound pressure was consistently recorded at approximately 105dB across all cases. This measurement indicates the peak sound intensity of the stimulus. The influence of the location of receiver, design, and space volume for the lecture room on the reverberation time was investigated. At a location of 6 m from the sound source, at the back wall of a room with chairs, BKN 5 and BPU 5 measured longer reverberation times of 1.3 s and 1.2 s, respectively. The higher value of reverberation time is caused by where the sound receiver is. If it is close to a wall, the sound receiver will be exposed to numerous reflections of sound waves, causing the room to become reverberant. Compared to other lecture rooms, the length of BKN 5 and BPU 5 is shorter. Their lengths are 11.639 m and 11.689 m, so the sound receiver is closer to the wall and makes the reverberation time higher. BKN 5 room, which has a volume of 258.3 m3, had the highest reverberation time (1.2 s on average in a room with chairs). This is because it is larger than the other rooms. So, the reverberation times get longer as the room's volume increases. BPU 5 room had the longest reverberation time for a condition room without chairs (an average of 2.4 s), but it also had the smallest space volume (242.4 m3) compared to the other rooms. Thus, it takes longer for the sound waves in the room to fade away when there are no chairs there. If the smaller room didn't have enough sound-absorbing materials, the reverberation times would be longer.
DETECTION MODEL FOR FAKE NEWS ON COVID-19 IN INDONESIA
Authors: Rifai Achmad Pratama , Mulyani Yun Prihantina , Febrianto Rian , Arini Hilya Mudrika , Wijayanto Titis , Lathifah Nurul , Liu Xiao , Li Jianxin , Yin Hui , Wu Yutao , Mohawesh Rami
Published: November 2023

Today, fake information has become a significant problem, exacerbated by the acceleration of access to information. The spread of fake information has a dangerous impact, especially regarding global health issues, for example COVID-19. People can access various resources to obtain information, including online sites and social media. One of the methods to control the spread of false information is detecting hoaxes. Many methods have been developed to identify hoaxes; most previous studies have focused on developing hoax detection methods using data from a single source in English. The present study is carried out to detect fake news in Indonesian language using multiple data sources, including traditional and social media in the context of COVID-19. The study uses Long Short-Term Memory (LSTM) and the Robustly Optimised Bidirectional Encoder Representations from Transformers Pre-Training Approach (RoBERTa). The LSTM approach is used to develop four different architectures that varied based on: (1) the use of text-only versus the use of both title and text; (2) the number of LSTM and dense layers; and (3) the activation function. The LSTM model with text-only data, a single LSTM layer and two dense layers, outperformed other LSTM architectures, achieving the highest accuracy of 92.17%. The LSTM models require a considerably short training time of 23–27 minutes for 3,847 articles and has a detection time of 3.8–4.1 ms per article. The RoBERTa classifiers outperformed all LSTM models with an accuracy of over 97% and a significantly better training time, with a margin of more than 50% compared to LSTM classifiers, although it had a slightly longer test time. Both LSTM and RoBERTa models outperformed the Naïve Bayes and SVM benchmark methods in terms of accuracy, precision, and recall. Therefore, this study shows that both LSTM and RoBERTa methods are reliable and can be reasonably implemented for real-time fake news detection.
TECHNO-ECONOMIC ANALYSIS OF TRIANGULAR ROOFTOP SOLAR PV MODEL/PLN ON-GRID HOUSEHOLD SCALE IN INDONESIA
Authors: Ansori Aris , Arsana I Made , Siregar Indra Herlamba , Adiwibowo Priyo Heru , Haryuda Subuh Isnur
Published: November 2023

The use of solar PV as an alternative to fulfill household-scale electricity needs has begun to be widely developed. However, the problem of investment costs and the location of solar PV placement for household scale is still a challenge in its implementation. The construction model of rooftop solar PV can affect the investment cost and performance of solar PV. In this paper, the triangle model of rooftop solar PV on grid with PLN (PT. Perusahaan Listrik Negara) electricity network is studied in terms of technology and economics to determine the feasibility of implementing 900 VA household-scale power plants. Testing the application of solar PV technology under solar radiation conditions in the city of Surabaya, Indonesia as a case study. Calculation of electricity production, energy savings, energy sales, and energy purchases to determine technological feasibility as well Net Present Value (NPV), Benefit Cost Ratio (BCR), and Payback Period (PP) to determine the level of economic feasibility. The results of the research of 1,5 KWP (kilowatt peak) solar PV technology on a household scale are able to meet energy needs and reduce PLN electricity purchases to 0% and can sell electrical energy by 13.96% / year of the total electrical energy produced. In addition, the NPV, BCR with a value greater than zero, and PP of 8.6 is less than 15 years which is the service life of solar PV, so solar PV/ PLN on grid is feasible to be implemented for household scale power generation models.
Robust Logistic Regression for Graduate's Employability from Public Universities in Malaysia
Authors: Tengku Mohamed Tengku Salbiah , Lee Muhammad Hisyam
Published: November 2023

The graduate’s employability is studied to investigate its factors involving graduates from public universities in Malaysia for the year 2016. This topic has become a concerning topic in Malaysia as the number of graduates getting hired is lower than expected and does not commensurate with the total number of graduates produced every year. The investigation on graduate’s employability based on their profiles is done by utilizing a robust method due to the existence of outliers in the data set. The analysis shows that age, CGPA, discipline, educational stage, English grade, entry qualification, gender, state, sponsor and university types are factors that affect Malaysian public university graduates. Overall, robust logistic model fits the data with correctly classified 69.65% and produces area under the Receiver Operating Characteristics (ROC) curve with 0.6961 in separating the groups of employed and unemployed graduates.
Mathematical Modeling and Analysis of the Dynamics of Chikungunya in Bangladesh
Authors: Haque Md Aminul , Chakraborty Amit Kumar , Islam Md Anowarul
Published: November 2023

Chikungunya is one of the major public health problems in Bangladesh and the effect of the disease is more virulent over the country. In this paper, a compartmental mathematical model has been proposed that describes the transmission of chikungunya disease in Bangladesh. Nonlinear incidence rate is considered for disease transmission and the system of nonlinear differential equations is developed to represent the model. Furthermore, the treatment term has been introduced in the model. The basic reproduction number, which is a biological threshold parameter for this disease, has been computed for the model by the method of next generation matrix. Disease free and endemic equilibrium points are calculated and the stability of the model has been analyzed using the basic reproduction number. The global stability has been established using the Lyapunov function theory. In this study, we have calculated the numerical value of the basic reproduction number and performed numerical simulations based on the real data collected from several health institutes of Bangladesh. Both analytical and numerical results provide a pattern about the dynamics of the disease in Bangladesh. Based on the effects, some important policies and insights are provided that might help in reducing the number of infected cases of chikungunya.
Flood Frequency Analysis using L-Moment For Segamat River
Authors: Badyalina Basri , Mokhtar Nurkhairany Amyra , Mat Jan Nur Amalina , Hassim Nor Hidayah , Yusop Haslenda
Published: November 2023

Flood frequency analysis is critical in water system design and estimating flood recurrence. This study aims to conduct the flood frequency analysis on Segamat River streamflow site to find the optimum distribution that fits the flood frequency data. In terms of estimating parameters, the L-moment method is more robust and more efficient than the maximum likelihood method. Besides, the L-moment method is not affected by sampling variability. Therefore, in this study, we applied the technique of L-moment for parameter estimation on five candidate distributions, the generalised Pareto (GPA) distribution, generalised extreme value (GEV) distribution, generalised logistic (GLO) distribution, log-Pearson 3 (LP3) distribution, and log-normal (LN3) distribution. The rank score approach is implemented to determine the optimum distribution for the annual Segamat River peak flow. Probability distribution identification is essential and it is a fundamental step in statistical analysis. The goodness of fit test and efficiency assessment are employed to evaluate the distributions' performance. The results show that the LN3 distribution is selected as the optimum function for the yearly peak flow for the Segamat River streamflow site. The outcome of this study can be used to understand the flood frequency analysis for the Segamat River.
On the YOLOv4 Architecture for Fast and Real Time Congenital Heart Disease Detection Via Ultrasound Videos
Authors: Nasrudin Muhammad , Iriawan Nur , Fithriasari Kartika , Apriliyanti Pravitasari Anindya , Hidayat Taufiq
Published: November 2023

Congenital Heart Disease (CHD) is one of the most frequent cardiac defects in infants, and it is becoming more common. Various research studies have been conducted for CHD identification based on clinical and non-clinical data. This study conducts an artificial  intelligence system for real-time congenital heart disease (CHD) detection using ultrasound videos. The YOLOv4 (You Only Look Once) is employed for localizing the congenital defect through ultrasound videos. The performance is evaluated by mean Average Precision (mAP) which compares the classification results with the medical ground truth. The model has great performance in CHD detection with mAP values of training data of 98.36% for YOLOv4 and 87.24% for YOLOv4 tiny. This is useful for doctors and radiologists who require a simple, fast, yet accurate model for the detection of CHD.
Efficient Market Hypothesis for Malaysian Extreme Stock Return: Peaks Over A Threshold Method
Authors: Marsani Muhammad Fadhil , Shabri Ani , Basri Badyalina  , Mat Jan Nur Amalina , Mohd Kasihmuddin Mohd Shareduwan
Published: November 2023

This paper presents investigation on the efficient market hypothesis of extreme stock return based on peaks over threshold method, by application of 10% Value at risk (VaR) quantile threshold level. The efficient market hypothesis (EMH) in the stock market index is validated by utilising autocorrelation, Kwiatkowski Phillips Schmidt Shin (KPSS), and variance ratio tests. The tests constituted of daily, extreme maximum and minimum, and three sub-periods data reflecting different economic condition in the market. Results indicated the strong influences of the financial crisis in the series movement. Mixed evidences were acquired; nonetheless, the overall results show that the Malaysia extreme stock return does not follow a random walk, only the series during the crisis and recovery period are in weak-form market efficiency.
MAP ANALYSIS OF LAND USE IN KHILAU SUB-SUB WATERSHED, WAY BULOK SUB-WATERSHED, WAY SEKAMPUNG WATERSHED, LAMPUNG PROVINCE
Authors: Herison Ahmad , Romdania Yuda
Published: November 2023

An increase in population impacts conditions of forest, soil, and water resources in watersheds through land use change. One of the hydrological components in the watershed influenced by this change is the surface flow coefficient (C). This study aimed to analyze the land characteristics of the Khilau Sub-Sub Watershed, Bulok Sub-Watershed, Sekampung Watershed, Lampung Province. The research methods involved taking aerial photos and field observation with an application called ArcView GIS MAP as the research tool. The analysis results signify that the land use in the watershed was divided into 6 main types with a total area of 671.6776 Ha. The surface flow coefficient value (Ctotal) was 0.1412, which indicates that all rainwater falling into the watershed was well infiltrated into the soil so that the land use was categorized as good. It was found out that, with the use of the GIS application, the land use in the Khilau Sub-Sub Watershed comprises 6 main types, i.e. mixed gardens, forests, annuals, shrubs, settlements, and rice fields. The mixed garden type of land use has the highest coefficient (C) value of surface flow runoff, so it Therefore, the rainwater in the watershed area is well infiltrated into the soil so that it is safe to categorize the land use as good.
STUDY OF THE PERFORMANCE OF WASTE PLASTIC IN CLAY SOIL STABILIZATION
Authors: Sarkar Razesh Kanti , Mahi Raihad Farin , Akter Mst. Masuma , Al Hussain Hameem , Sarkar Himel Chandra
Published: November 2023

Every year, tons of plastic garbage is produced, damaging our environment. So, recycling these waste plastic has become a need of this time. Therefore, using such materials in technical applications like soil stabilization will be advantageous. Additionally, stabilization using waste plastic is a practical option that is also easily accessible around us. In this research, the soil was stabilized with Waste Plastic. Waste Plastic and Bottle Strips were collected and used as soil reinforcement in this study to improve the engineering performance of subgrade soil. The plastic strips were cut in two distinct aspect ratios (5 mm x 5 mm) and (5 mm x 10 mm) and were prepared to add at two different weight proportions (1% and 2%). Unconfined Compressive Strength testing was then carried out. The testing findings revealed that shear strength parameters improved significantly. The current analysis yielded the following Compressive Strength values: 27.68 psi and 32.73 psi when 1.0% and 2.0% of plastic bottle strips (5mm x 5mm) were used, and 17.32 psi and 21.99 psi when 1.0% and 2.0% of plastic bottle strips were used (5 mm x 10 mm). The results demonstrate that in the instance of bottle strips, mixing smaller strip sizes created an increase in shear strength on the soil. Any additional increase in strip size has resulted in a loss in compressive strength because increasing strip size generates un-compacted weak shear planes. So, this can be concluded that using waste plastic in clay soil for soil stabilization is recommended since it helps to both reduce the cost of stabilization and protects the environment.
Insights Into Frictional Brush Seal Hysteresis
Authors: Phan H. M. , Pekris M. J. , Chew J. W.
Published: November 2023

Brush seals offer a superior sealing effectiveness compared to labyrinth seals. However, widespread use of brush seals is constrained by deleterious behaviors such as pressure-stiffening and hysteresis. For the latter, the bristles bend during the shaft incursion process and do not fully recover during the shaft retraction process. An opening gap is created, which increases seal leakage unless the pressure load drops to a certain level. In this work, analytical and numerical models based on a single bristle are proposed to capture the seal's response to shaft displacement with and without pressure loading. The models are validated using static stiffness tests at an unpressurized condition from literature. The main results show that modeling of the backing ring friction is essential to capture the bristle hang-up behavior. Shaft friction dominates at unpressurized conditions, while backing ring friction dominates at high pressure loading. An expression for shaft hang-up displacement has been derived. A sensitivity study shows that seals with shallow lay angle, short bristle length, and large bristle diameter are less prone to hang-up problems. The models developed in the present framework have been shown to qualitatively capture the pressure stiffening, hysteresis, bristle hang-up, and shaft rotation effects.
Test Temperature Selection Procedures for Small Specimen Master Curve Tests Considering the Possibility of Inhomogeneous Materials
Authors: Yamamoto Masato , Kirk Mark
Published: November 2023

Test temperature selection can be challenging in Master Curve tests following JEAC4216[1] or ASTM E1921[2], especially in situations when the available number of specimens are limited. In PVP2022-82754[3], the authors proposed an easy and objective procedure for selection of the next test temperature during a series of Master Curve KJc tests assuming sampling of a homogeneous material and demonstrated that a valid To can be obtained with high assurance using only N = 12 specimens even with a low KJclimit associated with a small specimen size of 4mm thick. In the present study, a series of Monte-Carlo analyses sampling from ideal bimodal KJc data sets, which are defined as the summation of two different homogeneous KJc groups that follow the assumption of the Master Curve Weibull distribution, demonstrated that the proposed test temperature selection procedure also works for the material with bimodality for a wide variety of combinations of reference temperature, To, yield stress σYS(RT), and bimodality. In general, it took 12 to 14 specimens to obtain a valid To with ≥ 95% success rate. Even in exceptional cases with the combination of relatively higher To, lower σYS(RT), and higher bimodality, a valid To can be obtained with high success using 16 specimens. It was found that those extreme cases require a few more specimens not because of the temperature selection procedure but because the KJc values sampled in such extreme conditions from higher toughness population of bimodal distribution are not free of censoring due to the plastic deformation even within the test temperature range within T = To ±50°C as specified in E1921.
Validation of Deformation in Crystal Plasticity When Modelling 316H Stainless Steel for Use in Pressure Vessels
Authors: Horton Edward W. , Spadotto Julio C. , Smith Albert D. , Donoghue Jack M. , Knowles David , Connolly Brian , Pickering Ed J. , Mostafavi Mahmoud
Published: November 2023

The safety critical nature of high temperature/pressure power plants means that understanding the mechanical behaviour of materials used remains a priority. Current design and assessment codes are conservative due to the macroscale estimates used in their construction so to improve these standards the mesoscale should be taken into account. A commonly used method to simulate this lengthscale is crystal plasticity finite element (CPFE) which allows for efficient simulation of mesoscale phenomena.

This paper presents and validates key components of a crystal plasticity model used to predict the deformation seen within 316-H stainless steel at elevated temperature. This validation is done by capturing intra-granular (type-III) stress profiles obtained using cross correlation of high resolution electron backscatter diffraction patterns (HR-EBSD) at different stages during loading to 3% plastic strain. Two exercises were performed to investigate the model’s ability to predict the correct active slip systems and slip transmission across boundaries.

The model was found to be able to correctly predict the most active slip system seen experimentally in 90% of grains. In addition to this the stress gradients observed near boundaries showed larger magnitudes at higher grain boundary misorientations in both the model and the experiment. The stress distributions explored matched between model and experiment for some boundaries but not all types. This may be due to the over simplification of the simulation geometry.
Comparison of Fatigue Models in API 1183 for Predicting Fatigue Life of Pipeline Dents
Authors: Zhu Xian-Kui
Published: November 2023

Pipeline dents are mechanical damage caused by a third party in buried pipelines during construction or maintenance repair. Since 2008, the Pipeline Research Council International (PRCI) has sponsored a large pipeline dent program on experimental tests, integrity assessment, and inline inspection of pipeline dents with and without interfacing other anomalies. For more than ten years, many experimental data, numerical results and assessment models have been developed. On this basis, American Institute of Petroleum (API) recently published a recommended practice (RP) 1183 – Assessment and Management of Pipeline Dents. This API code provides the pipeline industry “standard methods” for evaluating severity and predicting fatigue life of pipeline dents with a single peak.

This paper discusses fatigue methods prescribed in API RP 1183 for predicting fatigue life of pipeline dents. This API standard provides two types of dent fatigue criteria. One is screening methods based on dent fatigue life in Sections 7.4.1, 7.4.2, and 7.4.3 of API 1183. The other is assessment methods for predicting fatigue life of dents in Section 8.3.4. Because of complexity of fatigue methods and math equations given in the content, Annexes A.1 to A.5 in API 1183 provide a set of standard examples for calculating fatigue life, determining restraint condition, and evaluating the screening and assessment methods for plain dents. However, after careful examination, it was found that many issues and errors exist in this new API standard. In particular, comparisons using these Annex examples in API 1183 showed self-inconsistence between the screening methods and the assessment method. This paper presents the detailed fatigue life calculations, comparisons, and self-inconsistent results of the dent screening and assessment methods given in API 1183. On this basis, recommendations are made on how operators should use API RP 1183, and what actions API should take to improve this code.
Pipeline Stacked Crack Interaction Burst Pressure Analysis Using 3-D Crack Meshes
Authors: Holloman Ryan , Thorwald Greg , Turnquist Michael , Neuert Mark
Published: November 2023

Accurate evaluation of the remaining strength of cracklike flaws identified via pipeline inline inspection (ILI) or in-ditch non-destructive examination (NDE) is critical to ensuring continued safe operation of liquid and gas transmission pipelines. Modern pipeline ILI tools have sufficient resolution to detect longitudinally overlapping crack-like flaws that exist in the same radial plane, referred to as stacked cracks. Depending upon the crack sizes and pressure loading, stacked cracks can interact to reduce burst pressure below that of any of the individual stacked cracks.

Closely located cracks are often evaluated using interaction criteria, such as those provided by API 579-1/ASME FFS-1 Part 9 (API 579) [1], which specify how and when multiple nearby cracks can be combined into a single crack for the purpose of an integrity assessment. When applied to stacked cracks, the interaction criteria can often lead to recategorizing stacked cracks as a through-wall crack, which requires urgent response from the pipeline operator.

Here, an improved interaction criterion was developed for stacked cracks based on the results of elastic-plastic finite element analysis (FEA) models of multiple combinations of stacked crack sizes and orientations, pipe material properties, and operating stress. These improved interaction criteria provide pipeline operators with an easy-to-apply methodology to analyze stacked cracks that reduces the excess conservatism associated with legacy methods.
Bending Moment in Flange Design, Capacity, Allowable Loads and FEA Methodology
Authors: Lutkiewicz Przemyslaw
Published: November 2023

There are many types of flange and clamp connectors in use and described by different standards. Most of them are based on the linear elastic methodology and allowable stress concept (ASME, API flanges). More modern designs (ISO 27509 and NORSOK L-005 Compact Flanges, NORSOK U-001 subsea flanges) are based on elastic plastic principles and plastic collapse capacities. For all of them defining the tensile structural and functional limits is relatively transparent and seamless process. Often the external allowable Bending Moment load at rated Pressure is one of the most critical characteristics for subsea use and High-Pressure connections. To predict capacity and allowable Bending Moment is more complicated especially for modern flange types. In this paper author will focus and explaining already existing design methods with relation to the FEA assessment and modern connections structural and functional capability. The topic will be discussed based on the Compact Flange (ISO 27509 and NORSOK L-005) connection example and in related structural FEA long term functionality check based on DNVGL-RP-F112 recommendations (Hydrogen Induced Stress Cracking for subsea Duplex and Super Duplex material). In the presented example the focus will be on the flange itself, but the attached pipe also be included in the evaluation. The topic discussed in the paper and the conclusions are included in the FEA recommendation in the newest national NORSOK L-005 flange design code release.
The Experimental Investigation of Flow Induced Pulsations in Corrugated Flexible Pipes in Service With Supercritical Carbon Dioxide
Authors: Belfroid Stefan , González Díez Néstor , Meijer Irma , van Beek Pieter
Published: November 2023

Internally corrugated flexible pipes and hoses are prone to generate high amplitude tonal pressure pulsations (singing, also called FLIP). This is a common experience in flexible risers and flowline used in the offshore oil & gas industry. Models to predict the onset conditions when this singing occurs have been developed for this market. Similar flexible lines are and will be used for CO2 transport, for instance in CCS projects. The transport conditions will be mainly in the supercritical region. To verify if singing occurs in the supercritical region and if the prediction models are still valid, small scale singing experiments have been done with a 1.37m long 6mm ID hose with pure CO2 at conditions ranging from 2 to 180 bara.

Clear singing was shown to occur at all pressures with similar characteristics (Strouhal number and amplitudes) between CO2 operations as low pressure air conditions. The onset velocity could be matched based on an energy balance method and on a feedback criterion. The current tools employed for natural gas transport do need adaptions to be valid for CO2 transport calculations.

The main conclusion is that flow induced pulsations in corrugated flexibles are generated in CO2 at supercritical conditions and that when these type of flexibles are used for CO2 transport, the same screening is advised as is common for the use of flexibles for natural gas transport.
Effect of Bolt-Up Stress Level on the Strength of ASME B16.5 and B16.47 Standard Flanges
Authors: Bouzid Abdel-Hakim , Bouzid Sofiane , Benfriha Khaled
Published: November 2023

ASME B16.5 and B16.47 flanges are extensively used in the pressure vessels and pipping industry. The origin of their class and size is not based on the amount of initial bolt load they can carry nor the level of tightness they can achieve. Their PV rating does not give an indication on the level of stress they are subject to and little is known on their ability to withstand the bolt stress level they are subjected to during initial bolt-up and under operation. The integrity and leak tightness of ASME B16.5 and B16.47 made of SA105 material needs to be analyzed individually in order to identify the flange classes and sizes that are more vulnerable to initial bolt-up stress level.

This paper proposes the use of an accurate analytical model to appropriately address the integrity and tightness of the complex statically indeterminate weld neck standard flange connections based on the flexibility and the elastic interaction between the different joint elements. As such, the most critical standard flanges in terms of class and size will be identified in order to avoid their structural and leakage failure. The model is first tested and validated using simulations using FEM on different sizes of class 900 flanges. The study will investigate the effect of the initial bolt preload on parameters such as flange rotation and stresses in the flange, gaskets and bolts. The most critical size and class flanges and their highly stressed locations will be revealed.
Visualization of the Decomposition and Relief Process in High-Pressure Systems
Authors: Röblitz Aaron , Busch Markus
Published: November 2023

The prevention of decomposition plays a crucial role in polymer chemistry. Since these cannot be completely avoided, e.g., due to the formation of hotspots, a sound knowledge of the decomposition characteristics and the resulting relief process is of enormous importance. Essential parameters are the flame front velocity, the maximum pressure, and the pressure change rate, but also factors such as the flame front geometry, which has a considerable influence on the burning velocity and the relief process. Within the scope of this work, the described parameters are investigated with the aid of a view cell as a function of various variables. The influence of the ignition and relief position, the composition, and the pressure and temperature conditions are considered. Here, the focus is mainly on the conditions in a high-pressure separator, for example in the LDPE production process. By using fast-response pressure and temperature sensors and a high-speed camera, time-resolved results can be obtained that provide information about the decomposition and relief process.
Semi-Empirical Modeling of Irradiation-Induced Dimensional Change in H-451 Nuclear Graphite
Authors: Johns Steve , Windes William E.
Published: November 2023

Nuclear graphite has been used as a moderator material in nuclear reactor designs dating back to the first reactor to reach criticality, Chicago Pile 1, in 1942. In addition, it is anticipated to be used in the conceptual Generation four (GenIV) Molten-salt reactors (MSRs) and the High-temperature gas-cooled reactors (HTRs). The macroscopic dimensional change observed in irradiated nuclear graphite is a property change of significant importance. Largely, volumetric change provides valuable insight into the in-service lifetime of graphite components used in nuclear reactors. The dimensional change behavior varies amongst each grade of nuclear graphite due to processing techniques and the resulting microstructure. In this work, historic data for nuclear graphite H-451 is revisited. A semi-empirical methodology is proposed to describe the dimensional change behavior as a function of temperature for nuclear graphite H-451. The turnaround dose, or when there is a reversal of the dimensional change from contraction to expansion, is proposed to be a thermally activated process and thus can be described by an Arrhenius model. On the atomic scale, H-451 is sp2-bonded carbon atoms with some degree of disorder regardless of orientation. Towards that end, the activation energy is assumed to be a constant irrespective of orientation.
Flow Induced Vibration of Piping Systems
Authors: Antaki George
Published: November 2023

This paper provides a logical, step-by-step approach to address flow-induced vibration in piping systems and pipelines. Starting with immediate actions when significant vibration is observed, followed by root-cause determination with a description of the various sources of vibratory excitation, proceeding to monitoring techniques to monitor the hydraulics or the vibratory motions, determining the degree of severity of the monitored parameters, and providing the full range of hydraulic and structural options to reduce or eliminate the vibration. The paper addresses the existing standards and criteria for flow-induced vibration in piping systems, across industries.
INCEFA-SCALE (Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment - Focusing on Gaps Between Laboratory Data and Component-Scale)
Authors: McLennan Alec , Cicero Román , Beswick Jack , Courtin Stéphan , Que Zaiqing , Cicero Sergio
Published: November 2023

INCEFA-SCALE is a five-year project supported by the European Commission HORIZON 2020 programme. INCEFA-SCALE kicked off in October 2020 and is the successor to the INCEFA-PLUS programme that ran from 2015 to 2020. The objective is to continue working towards advancing the ability to predict lifetimes of Nuclear Plant components when subjected to Environmentally Assisted Fatigue (EAF) loading.

Nuclear Plant operators have generally observed that the number of failure events attributable to EAF are fewer than predicted by current assessment methodologies. It is internationally recognised that a contributor to this discrepancy is the transferability of data from laboratory-scale tests to real nuclear components. This is the main knowledge gap addressed by INCEFA-SCALE. The project strategy will be (1) the development of mechanistic understanding developed through detailed examination of test specimens and data mining from large fatigue datasets, and (2) testing and analysis focussed on aspects and features of component-scale cyclic loading. The project has created tools to survey the fatigue data within JRC’s database and feed screened data into analyses. In parallel, a testing programme has been specified and is underway. The testing programme is focussed on studying the effect of variable amplitude loading, environment, surface condition, and specimen geometry on the fatigue life of stainless-steel specimens. A materials characterisation work package is investigating the effect of the test conditions on fracture surfaces and combining that analysis with a range of materials properties and test data to contribute towards an improved mechanistic understanding of EAF. An analysis work package is actively working on scientific and engineering models to inform predictions of specimen life and develop approaches to account for the conditions studied in EAF assessments. Finally, the project will deliver guidance on the use of laboratory-scale data for component-scale applications.

This paper will outline progress from the first two years of the project. Specific details relating to the testing, materials characterisation, and analysis work packages will be presented in additional papers and presentations during the INCEFA-SCALE session.
Models for Estimating the Autofrettage Pressure and Residual Stresses in Walls of Type 2 Pressure Vessels
Authors: Tang Tsz Ling “Elaine” , Sripragash Letchuman “Sri” , Narasimhachary Santosh B. , Saxena Ashok
Published: November 2023

Autofrettage is a manufacturing process used during fabrication of Type 2 pressure vessels designed for usage at high pressures to enhance the fatigue life. The process locks high compressive residual stresses in the vessel’s liner wall that reduce the maximum and the mean stress during service loading. To achieve a consistent residual stress profile across the wall of the vessel, the choice of autofrettage pressure is critical. Several finite element analyses runs were conducted to estimate the correct autofrettage pressure that is a function of the yield strength of the liner material, the wall thickness, and the outside diameter of the liner for a wrap thickness of 17.06 mm (48 wire layers). From the finite element analyses results, models were developed to estimate the correct autofrettage pressure and the residual stress distribution across the liner wall as a function of the yield strength of the liner material, the wall thickness, and the outside diameter of the liner.