bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigations of Groundwater and Soil Specification at AL-Warrar Canal Reach, Ramadi City-Iraq
Authors: Abbood Rea’am T , Mustafa Ayad S , Al-Somaydaii Jumaa A
Published: August 2023

The study area is located in Anbar Governorate, western Iraq, within the city of Ramadi, in the area adjacent to Al-Warrar Canal. The study area suffers from a lack of previous hydraulically studies, hydrological, the geological, and topographical characteristic and the soil characteristics, also suffers from a significant increasing in levels of groundwater. Three wells were drilled in area adjacent of the Al-Warrar canal with a diameter of 0.1524m, 10m in depth and 100 m the distance between each well, to observe water level of the groundwater with the change in the levels in Al-Warrar canal. The physical properties of soil, as well as their chemical properties, were studied in order to straighten. According to these tests, the soil of the study area was found to have a high concentration of sulfite, gypsum, salts and moisture content in the upper layers of clayey sand and clay, with low plasticity. As well as the increase of level in Al Warrar Canal water leading to an increase the hydraulic heads in the groundwater level in the area of study. Depending on the two possibilities were taken for the movement and transmission of groundwater, one of which is the movement of groundwater from the study area to Al Warrar Canal and the other is groundwater movement from the canal to the study area depending on the increase and decrease in the water level of Al Warrar Canal.
Morphological of the Euphrates River between Al-Qaim and Hit City Using Modern Technology
Authors: Jassim Saad M , Mohamed Fouad A , Abdullah Taha Y
Published: August 2023

The study aims to illustrate the River characteristics, river morphology and river processes in the study area Landscape. The river and morphological variables used in the study were derived from the satellite imageries available, digital elevation models, and relevant maps. River morphology is used to describe the shapes of river channels and how they change in shape and direction over time. River channel morphology is an indicator of a number of environmental processes and conditions. The river channel is the product of many geographical and geomorphological components that are determined by many factors, which are independent variables of the landscape (Geology, Climate, And Man) and reflect their influence in shaping the variables dependent on the landscape and the channel (sediment supply, stream discharge, and vegetation). Based on the aforementioned variables, the landscapes of the Euphrates River profile between the cities of Al-Qaim and Hit were chosen, which affect the formation and development of the channel. Where it leads to creating the shape of the planform and the active river area. The topography of the study area is characterized as a plateau crossed by the Euphrates River. It was affected by tectonic activity and this was reflected in the shape planform and geomorphic characteristics.The length of the river distance for the studied profile is 348 km, and it was divided into four reaches.It appeared that the index of this distance is characterized by sinuosity, as it reached 1.4, now the meanders are present in the second and fourth reach, while braiding prevailed in the first reach. The emergence of human settlements and increased until the present time, represented by the construction of a group of dams on its basin. It led to the occurrence of a series of hydrological and geomorphological changes, which necessitates the restoration of this basin and finding ways to ensure the stability and well-being of the inhabitants of its basin.
Water Management of Agricultural Lands in Diyala Governorate
Authors: Kazkoz Kamal S , Al-Azzawi Monem A
Published: August 2023

The existence of a large water deficit in Diyala Governorate, especially in July and August of the year 2020-2021 AD, and the reasons are due to the natural factors to which Iraq in general and the study area in particular were exposed, such as thermal inclusion and lack of precipitation, and human factors that are specific to the water policies of neighboring countries and events After 2003, a number of factors and field manifestations also combined to complicate the picture of the water deficit in the study area, represented in the pollution and lack of purification of waterways and the disruption of many water barriers and lifting stations. It was found from the results of analyzes of river water samples The drains have a quality within the second category (C 2). As for the drainage water, it was shown that it has a salinity of (2215-2230) micromoz / cm, and it falls within the third category (C3) and it is of high salinity. This water is used only in the presence of an effective drainage network and for crops High tolerance to salinity.
Effect of Surface, Subsurface Drip Irrigation and Nanotechnology Perfusion Methods on Irrigation Efficiency and Saved Water Ratio in Plowed and Unplowed Soils
Authors: Al-Shaabani Ehab M , Al-Obeid Abdilwahab K , Alrubaye Arkan A , Wissam A , Ahmed Yasser M , Al-maamri Haider A , Al-budeiri Muntdher H
Published: August 2023

A field experiment was conducted in Al-Habbaniyah district / Al- Khalidiya district / Al-Anbar governorate, western Iraq, in Silty loam soil during the fall season 2020, to study the effect of surface and subsurface drip irrigation and perfusion irrigation with nanotechnology on irrigation efficiency, the amount of added water and the percentage of water saving in plowed and non-plowed soils. Perfusion was done when 50% of the prepared water was depleted. The treatments were distributed according to the Nested-Factorial Experiments Design (NFED) with three replications. The yellow corn, cultivar Euphrates, was planted on 2020/15/7. The American evaporation basin, type A, was used in the timing of irrigation. According to the rate of water consumption in terms of the equivalent depth of the added water, the total yield and the efficiency of water use. The results of the study showed the uniqueness of the drip irrigation system by giving the highest irrigation efficiency of 100% for the two plowing modes, while the surface drip irrigation system gave an irrigation efficiency of 83% in the uncultivated soil, and the lowest amount of water was added during the season, which amounted to 5215 m3. ha-1 in the nano-technology perfusion irrigation method with a savings rate of 29.97 and 13.19% compared with the surface drip irrigation method, while it reached 15.23 and 8% compared with the subsurface drip irrigation method in the plowed and non-plowed soils sequentially, the highest average total production was 11.7 tons of grain per hectare for the tillage and no-till treatment, and it decreased significantly to 7.5 tons ha-1 in the surface drip irrigation method, while the tillage treatments did not record significant differences in the short-term grain yield.
Water Balance for the Euphrates Aquifer, South of Haditha District, Al-Anbar Governorate
Authors: Al-Dulaimi Ali M , Al- Shammaa Ayser M
Published: August 2023

Groundwater balance calculation was carried for the Euphrates aquifer extended in the southern parts of Haditha district within Al-Anbar Governorate, where the Euphrates aquifer in this area is considered as unconfined with a flow direction towards the Euphrates River. The yearly recharge quantity for the Western Desert catchment-basin (1664.19 ×106 m3/year); whilst the ground-water quantity that intervenes study area (1155926.53 m3/ year), as regenerated storativity. The quantity of consumed ground-water in the area through the present study (423567.36 m3/year) for both industrial and domestic uses. Therefore, the quantity of the ground-water storage change (ΔS) you will be (732359.17 m3/year). It is obviously that there is an increase in the continual storativity and the regenerated storage is sufficient to cover the water requirement.
Daily Evapotranspiration Prediction at Arid and Semiarid Regions by Using Multiple Linear Regression Technique at Ramadi City in Iraq Region
Authors: Mohammed Ahmed S , Al-Hadeethi Basheer , Almawla Atheer S
Published: August 2023

For many decades, because of the climate change, the interest in water resources management have been increased. The researchers curried out huge efforts to investigate the factors that influence the water resources quantities. Many of these efforts focused on studying the water losses by evapotranspiration. In the current study, a new mathematical model is introduced. It was built based on Multiple linear regression method (MLR). This model was utilized to estimate the daily evapotranspiration in Ramadi city which characterized with arid and semiarid environment and to investigate the influence of different parameters on the evapotranspiration process. The field data were collected from the digital meteorological station at the Upper Euphrates basin Developing Centre during the period from 23/11/2020 to 1/10/2022. These data include the evapotranspiration, maximum temperature, the minimum temperature, the average temperature, wind speed, relative humidity, and solar radiation. The model was calibrated using 80% of the data set, while 20% of the data set were used for validation. The solar radiation shows the highest impact on ET, while the lowest was recorded by relative humidity. High performance of the model was proved by testing it using Performance Indicators such as RMSE, NAE, MAPE, NSE, and R2.
Removal of the Minerals Salts from Water Wells by Using the Solar Distillation
Authors: Ahmed Rand R , Karaghool Haneen A. , Ismail Nizar N , Alabdraba Waleed M
Published: August 2023

Using groundwater optimally is a science in itself if this process is used or applied correctly. Distillation is a series of industrial processes carried out to remove all or part of excess salts and minerals dissolved in water so that such water can be used in practical life such as agriculture, drinking and industry. Desalination requires expensive and highly energy-consuming techniques that have adverse effects on the environment. The amount of energy consumed in the desalination is an important problem that needs to be overcome. In this study, we aim to investigate the solar desalination by using samples of wells water to determine the concentration of some of the most important physical and chemical properties and salts in these wells. A solar distillation device was manufactured locally for this purpose. Two samples were taken monthly from five wells for period of three months, and 6 of the physical and chemical tests were carried out. The results show the water obtained from this method suitable for domestic human use, such as cleaning and washing, but not suitable for drinking due to its high hardness and unless submit to sterilization. Solar distillation is a simplified system; materials are locally available and inexpensive. It does not require large capital upon installation and operation and maintenance.
Estimate Raw Water Salinity for the Tigris River for a Long Time Using a Mathematical Model
Authors: Kadhim A , khadhair Basim H , Jaafar Mahdi S
Published: August 2023

The measurement data of the raw water quality of Tigris River were statistically analyzed to measure the salinity value in relation to the selected raw water quality parameters. The analyzed data were collected from five water treatment plants (WTPs) assembled alongside of the Tigris River in Baghdad: Al-Karkh, Al-Karama, Al-Qadisiya, Al-Dora, and Al-Wihda for the period from 2015 to 2021. The selected parameters are total dissolved solid (TDS), electrical conductivity (EC), pH and temperature. The main objective of this research is to predicate a mathematical model using SPSS software to calculate the value of salinity along the river, in addition, the effect of electrical conductivity on the salinity value was estimated. Multiple linear regression (MLR) and artificial neural network (ANN) models were used to estimate the mathematical models for calculating water salinity value in Tigris River and to present the highest effective parameter that effect on water salinity. In general, the results showed an increase in the water salinity level downstream of the Tigris River towards the south of Baghdad and the EC is the most significant effect on water salinity, and MLR and ANN analyses present a good indication of the mathematical models with highest coefficient of correlation (R2) as (0.999 and 0.998), respectively. In addition, the regression equations proved good performance in predicting the salinity value with error percentage less than 10% for all WTPs.
Hydrochemical Study of Artesian wells in Babylon Governorate - Middle of Iraq
Authors: Al-Turaihi Ahmed S , Khawaja Ahmed M , Shaker Inas H , Al-Zubaydi Jaffar HA
Published: August 2023

This study tended to evaluate the quality of groundwater of three artesian wells (free ground water) distributed randomly in the province of Babylon in order to knowledge a better using of this water. Three water samples were chosen from each well to achieve this purpose. Groundwater samples were analyzed in the laboratory of the department of applied geology in terms of the following variables: total dissolved substances (TDS), electrical conductivity (EC), positive cations and negative ions, and the heavy elements. The results showed that the water of the artesian wells 1, and 3 have extreme salinity, whit high Electrical Conductivity ranging from 3200 to 8800 µS/cm. In addition, they are characterized by exceeding the critical limits for the percentage of magnesium and show more extent of the sodium element through a high percentage of soluble sodium (SSP%)and they were characterized by exceeding the permissible values for chloride ions. And also, the analysis result of heavy elements shows wells 1 and 3 have slight copper contamination and high cadmium contamination, so that my causing damage in plant growth. While the analysis results of water of well 1 confirm to be valid for the irrigation of sensitive plants. Our recommendation is good management of water resources is essential for preserving the region's soil and surface water and reducing underground pollution.
The Effect of Treated Sulfur Water on the Microbial Content of the Soil and the Extent of Resistance of These Bacteria to Antibiotics
Authors: Farhan Muthana B , Ali Hala A
Published: August 2023

The research began on March 7, 2021, as the regions of Ain Al-Wusta and Ain Jarura were chosen to take soil samples. The sulfuric water was treated using laboratory batch reactors. Locally manufactured glass tubes were used, with dimensions 17 * 17 * 55 in length, width and height, respectively, Subsequently, microbiological and chemical analyzes of the soil were performed. The results of the study showed success of the physical treatment process that was used to reduce the levels of sulfur in the water Depending on the source of water and the type of material used, the triple-magnetic treatment achieved the highest removal rate of 73% in Ain Al-Wusta soil, 40% in soil sample B1, and 27% in soil sample B2 of Ain Jarura. The results of bacterial culture showed that Gram-negative bacteria were dominant by 100% in soil samples from Ain Jarura region treated with untreated sulfuric water (WA1, WA2, WA3) (Table- 4), as well as for the same soil samples treated with sulfuric water treated with sand filter (GB1), charcoal filter (GB2) and magnetic field filter. (GB3) Soil samples treated with untreated sulfur water were dominated by Pseudomonas aeruginosa with a percentage of 66.7% and Acinetobacter lwoffii with a percentage of 33.3%.The results of the bacterial count of soil samples from the Ain Jarura region showed that there were significant differences between the bacterial number with sulfuric water treated with the three filters, As for soil samples from Ain Al-Wusta region, only soil samples added to sulfuric water treated with charcoal filter (WB2) gave significant differences with a significant decrease of number (84×102 CFU) for the species Aerococcus viridans. The results of the antibiotic sensitivity test showed that Elizabethkingia meningoseptica gave the highest rate of resistance to antibiotics about 66%. The results of the study showed that the resistance of bacterial isolates to antibiotics did not show significant differences between soil samples treated with treated and untreated sulfur water, except for the GB2 isolate.
Maritime Emergency Preparedness – Drifting Ships
Authors: Berg T E , Selvik Ø , Indergård R , Ringen E
Published: August 2023

The Norwegian Coastal Administration registers maritime incidents in Norwegian waters. Drifting ships and drifting objects may cause serious incidents and possible disasters. By analysing ship traffic in Norwegian waters, it is documented that the frequency of drifting ships has been approximately 0.15% of the registered ship transits, or 150–165 drifting cases annually. In addition to a possible grounding when a vessel reaches the coastline, the increased use of the ocean space for wind farms, floating solar installations, and fish farming structures (moving from sheltered coastal sites to exposed locations) increase the risk of collision with different types of ocean structures, including offshore oil and gas installations. The need for adequate emergency preparedness to prevent drifting ships from colliding with different types of ocean structures or a final grounding can be solved through different types of mitigating measures. One measure could be to have dedicated emergency towing vessels for handling vessels drifting towards ocean structures or on a course leading to a possible grounding. A reliable tool for predicting a drifting vessel’s path is important for planning an emergency towing operation. Systems to provide a fast and safe setup of an emergency towing connection under different environmental conditions are needed, while the competence of the crew on the emergency towing vessel and the ship to be towed is a critical factor for a successful emergency towing operation under adverse conditions.
Numerical PMM test in shallow water using CFD method
Authors: Zhu Zhang , Kim Yonghwan , Choi Jun-Hoi
Published: August 2023

This study aims to the estimation of the ship manoeuvrability in shallow water by using the numerical PMM approach, which analyses the hull hydrodynamic responses and manoeuvring performance from the viewpoint of coefficients. The test model is a scaled KVLCC2 tanker operating at a low Froude number of 0.0514. Static drift test and pure yaw test are considered, and the water depths vary from deep water to very shallow water of 20% under-keel clearance. The numerical tank is built based on an OpenFOAM+ package. The free surface is modelled by volume-of-fraction method, and the k-ω SST model associating with wall functions is applied for turbulence. After the convergence tests and validation works, the numerical tank is employed to investigate the wave-depth effect on hydrodynamic forces and manoeuvring coefficients. The present results show that the forces of static drift test, particularly sway force, can be significantly changed as the water depth decreases.
A numerical investigation on ship-ship overtaking interactions in confined waterways
Authors: Zheng Z Q , Zou L , Zou Z J
Published: August 2023

The whole process of a KCS container ship overtaking a low-speed Neo-Panamax container ship is numerically simulated by solving the unsteady Reynolds Averaged Navier-Stokes (URANS) equations. The dynamic overset mesh technique is adopted to simulate the relative motions between the two ships and the ship attitude variations. The free-surface elevations, ship attitudes, as well as hydrodynamic forces and moments on the two ships are predicted. In order to discuss the effects of different navigation parameters on the ship-ship interactions, a set of ship speeds, lateral distances and water depths are simulated. The results illustrate that the overtaken ship is more significantly impacted by the interaction than the overtaking ship, and the drawdown generated by the overtaking ship is the key factor during the overtaking process. The increase of ship speed, the decrease of lateral distance or water depth can lead to more intense drawdown, and hence even more significant ship-ship interaction effects.
Towards accurate stereo-video based free-surface reconstruction for wave tank experiments
Authors: Page Sacha Le , Tassin Alan , Caverne Julien , Gall Yves Le , Gomez Benoit , Ducrozet Guillaume
Published: August 2023

Measuring accurately the shape of the free surface in medium-scale hydrodynamic testing facilities is challenging with conventional wave gauges. To overcome this problem, it is necessary to go towards higher resolution measurement systems. For this purpose, we investigate the ability of stereo-video acquisition systems to reconstruct free surface waves in laboratory conditions. This technique has been proven to give satisfactory results in open sea conditions, although it is dependent on the environmental conditions (weather, solar incidence angle). At sea, the stereo-video reconstruction algorithm makes profit of the short waves generated by the wind in order to correlate the points from the left and right images. The main challenge of adapting this technique to laboratory conditions, i.e. in absence of sun and wind, is to overcome the absence of texture on the free surface. This paper presents recent work aiming at developing a stereo-vision measurement system for laboratory conditions. Our efforts have been devoted to finding an adapted lighting system and generating a texture suitable for the reconstruction algorithm. Different lighting configurations have been tested in order to understand its impact on the reconstructions. For the texture generation, we have investigated different means of generating short surface waves (water droplets, air blowing, circulation current, underwater acoustic emissions) in different experimental facilities. Our conclusions show that it is possible to reconstruct the shape of surface gravity waves in the presence of short surface waves and that the effects of lighting and texture on the quality of the reconstruction are strongly coupled.
Hydroelastic analysis of wave diffraction by multiple flexible porous plates
Authors: Sasmal Anjan , De Soumen
Published: August 2023

The study investigates the phenomenon of wave diffraction by multiple poroelastic plates in infinitely deep water using the two-dimensional linearized potential theory. The study focuses on numerically computing the reflection and transmission coefficients using Galerkin approximations specifically designed for two nonidentical vertical poroelastic plates. By varying the separation lengths, porosity, and flexural rigidity of the plates, the study explores the hydrodynamic quantities associated with the wave-plate interaction. These quantities are then represented graphically to visualize their behavior under different conditions. The results of the study show that the flexural rigidity of the porous plates has a significant effect on wave reflection and transmission. The correctness of the method used in the study is confirmed by comparing the results available in the literature. Overall, the study provides valuable insights into the behavior of waves interacting with multiple poroelastic plates and highlights the importance of considering the flexural rigidity of the plates in such systems. The numerical approach used in the study can also be applied to other similar problems and can provide a useful tool for predicting the behavior of waves in complex systems.
Coupled Lattice Boltzmann and Discrete Element Simulations of Ship-Ice Interactions
Authors: Watanabe Seiya , Hu Changhong , Aoki Takayuki
Published: August 2023

Evaluating ice loads acting on ships is essential for the safety of ships navigating in ice-covered seas. In this study, we develop a CFD method to handle ship, ice, and fluid interaction. The lattice Boltzmann method, capable of large-scale calculations, is applied to the simulation of free-surface fluids. The ice motion is computed by solving the equations of motion of a rigid body, and the discrete element method models the ice-ice and ice-ship contact interactions. A momentum exchange scheme couples the lattice Boltzmann method and particle-based rigid body simulation. We introduce tree-based adaptive mesh refinement and multiple GPU computing to improve grid resolution and computational time. The proposed method is applied to model scale simulations of ship navigation in a brash ice channel. Simulations were performed for various conditions with different ice concentrations and ship velocities, and we observed that ice resistance increased with the ice concentration and the ship velocity increased. The ice motions and resistances obtained from our simulations are reasonable compared to model equations of Finnish-Swedish ice class rules (FSICR) and numerical analyses of a previous study.
Ship motions and unsteady pressures on ship hull in oblique waves estimated by potential-based solvers
Authors: Suzuki K , Takeda K , Iida T , Yanagimoto F
Published: August 2023

The seakeeping performances in oblique wave conditions, such as ship motions and unsteady pressures on a ship hull, are getting more important, recently. These physical quantities are used for estimating loads induced by waves and evaluating the safety of a ship. Thanks to the evaluation of various incident wave angles, a rational ship design with sufficient safety and less construction cost can be realized. Therefore, the estimation by numerical schemes in those conditions is demanded for the ship design. However, schemes were usually validated through the comparison with experimental data in only heading wave conditions because few towing tanks can carry out the experiment for a ship advancing in oblique waves. The computed results in oblique waves should be validated well before the industrial usage of schemes. Although Computational Fluid Dynamics is useful to know the seakeeping performance in oblique waves thanks to the development of computer performance in these years, it takes much longer time than the schemes based on a potential theory. For this reason, three solvers based on the potential theory, the Salvesen-Tuck-Faltinsen method, the Green function method, and the Rankine panel method, are validated by comparing ship motions and unsteady pressure on the ship hull obtained from towing tank tests in oblique wave conditions.
Optimization of a coupled launching process considering hydrodynamic interaction effects
Authors: Altenbach L , Wermbter M , Marleaux P , Abdel-Maksoud M
Published: August 2023

Crane-assisted launching and recovering of small boats from a large vessel is common in a wide range of operational scenarios and may be required during research missions or in emergency situations for rescue boats. As the mothership moves in natural irregular seas, the resulting accelerations and motions of the small boat can lead to dangerous situations, such as a collision between the mothership and the small boat or a slamming of the small boat onto the free water surface can occur, posing a great danger to the people involved. In the paper, the development of a coupled simulation method for the motions of the mothership and the small boat during the launching in the time-domain is described. The developed simulation method is based on the impulse response function. The implementation of the suspension on a crane is realised by a holonomic constraint and a Lagrange’s equation. The parameter influencing the launching operation include the current sea state, the stationary wave field induced by the motherships forward speed, at which the small boat is launched and the initial position of the small boat relative to the water surface. By varying the above mentioned parameters, the process can be optimised for different sea states in terms of forces and accelerations. In considering the forward speed of the mother boat during the launching process, it can be observed that in many cases the small boat is operated at high Froude numbers of greater than 0.4. This leads to an exceedance of the operational limits of the programmes used in this paper.
An attempt to predict planing hull motions using machine learning methods
Authors: Shehata Ahmed , Dashtimanesh Abbas
Published: August 2023

Designing a high-speed craft for better seakeeping in waves can contribute significantly to higher safety and human comfort. Early in the design process, mathematical models such as the 2D+T method are commonly used, while high-fidelity computational fluid dynamics (CFD) and experimental models are used later in the process. Some of the limitations of such models are that they are not fast enough to be used in the ship’s system for real-time monitoring or to develop a digital twin. Recently, machine learning methods have demonstrated great promise in building surrogate models from data. These methods include deep learning and recurrent neural network (RNN). In this paper, a systematic investigation of the network architectures and the used optimizers to train the network is presented. Adam, Adagrad, RMSprob and SGD are investigated in training the network. To train the model almost 35000 data points were collected for Fridsma hull operating in 18 regular waves using a 2D+T model. The result showed that gated recurrent unit (GRU) outperformed long short-term memory (LSTM) and RNN in predicting the heave motion. Also, one hidden layer with 5 neurons was enough to achieve mean absolute error of 0.000298 and to predict unseen waves when trained with more than 24000 data points.
Numerical simulations of towing a jacket foundation with triple buckets
Authors: Tan Lei , Hu Changhong , Liu Yingyi
Published: August 2023

Offshore wind energy is developing fast as a promising renewable energy resource that can be helpful in achieving the global net-zero emissions goal. In recent years, offshore wind turbine projects have gradually moved towards far-offshore sea areas, where massive jacket foundations with suction buckets are suitable options. To reduce transportation costs, the wet-towing method is usually favourable since the required buoyancy of the foundation can be provided by the air cushions in the suction buckets. This engineering background brings us a research topic that involves towing and air cushions in waves. This study considers the towing problem of a jacket foundation with triple suction buckets. First, numerical analysis in the frequency domain is conducted using WAMIT®. In particular, the NEWMODES subroutine is extended to consider three separate motion modes in the buckets. Numerical predictions of the natural period show satisfactory agreement with the available experimental data in the literature. Moreover, a time-domain numerical model is developed to simulate towing of the jacket foundation in regular waves based on the potential flow theory. The time-domain model numerically solves the towing force in regular waves, the body motions and the air pressures in the buckets. The simulation results generally agree well with the published experimental data. Besides, the present simulation results suggest that the transit towing force and the forward speed of towed triple-bucket jacket may be considerable in the initial towing stage.
Experimental study on the hydrodynamic characteristics of a Bragg breakwater with triple vertical plates
Authors: Wu Jing-Ping , Luo Hong-Ye , Zou Zao-Jian , Chen Peng , Qi Jing-Jing , Xu Xing-Yu
Published: August 2023

The hydrodynamic characteristics of a Bragg breakwater with triple vertical plates in monochromatic regular waves are experimentally studied. The two spacings between the every two adjacent plates are denoted by S
1 and S
2 respectively which are both wide enough for the necessary of Bragg reflection, and S
2 is equal or unequal to S
1. A series of experiments are carried out in the wave flume equipped with a piston-type wave generator, and the hydrodynamic performance are analysed with the variation of the spacing S
2, the plate draft d
1 and freeboard d
2, the wavelength L and the wave steepness H/L (H is the wave height). Special attention is paid to the effects of nonuniform spacings on the hydrodynamic performance and the characteristics of Bragg reflection. In addition, the comparisons between the fixed and the unrestrained positioning are also presented. The results show that the transmission coefficients of the two unequal spacings mostly are smaller than the two equal spacings, and the intensity and bandwidth of Bragg reflection are increased by the non-uniform spacings. Under the unrestrained positioning, the movements have no serious effects on the wave attenuation performances of the breakwater. Moreover, the trough of transmission coefficient occurs at the left of the primary Bragg reflection condition due to both of Bragg resonance and wave energy dissipation not just Bragg resonance.
An experimental and numerical hydrodynamic study on the Argentinian fishing vessels
Authors: Oyuela S , Sosa R , Otero A D , Arribas F P , Diaz-Ojeda H R
Published: August 2023

The purpose of this work is the validation of the hydrodynamic resistance for a small fishing vessel providing more details about the ship’s hydrodynamics. The selected ship is a traditional vessel that has been sailing in Argentina for more than 20 years without a previous numerical resistance evaluation. Because of the absence of previous numerical optimization, the ship might be a non-efficient vessel from a consumption, operating and polluting point of view. For this reason, in order to bring a more detailed evaluation of the flow around this hull, numerical studies are carried out with the open source OpenFOAM code and validated with experimental results obtained at the University of Buenos Aires towing tank. Reynolds Averaged Navier Stokes (RANS) method together with volume of fluid (VOF) are used for the numerical procedure. Once the resistance results are validated, the total resistance coefficient is split into viscous and wave coefficients in order to provide insight into ship hydrodynamics. Pressure distributions on the hull and wave patterns will be also presented for different ship loading conditions, focusing on the flow around the hull that might give information for a future hull optimization.
Numerical study on wave-induced drift forces and motions of a DTC ship in head and oblique waves using functional decomposition model
Authors: Fang Xianjin , Yu Jiawei , Yao Chaobang , Zhang Zhiguo , Wang Xianzhou
Published: August 2023

It is imperative to investigate the adequacy of propulsion power and steering mechanisms in order to maintain the manoeuvrability of ships in adverse wave conditions, as the drift forces caused by wave can result in deviation from the desired course. The primary objective of this research is to develop a hybrid approach, combining potential and viscous flows, known as SWENSE (Spectral Wave Explicit Navier-Stokes Equations), to accurately assess the wave-induced drift forces and motions experienced by ships in waves. SWENSE is a hybrid approach based on the functional decomposition model, in which the total field is composed of the incident field and complementary field. In this study, the incident filed waves are calculated by the Airy wave theory and the complementary field is solved by the SWENSE model. The wave conditions are selected according to the benchmark cases of the European Union research project SHOPERA (Energy Efficient Safe Ship Operation). The wave-induced loads and motions of DTC in head and oblique waves are calculated. Results of CFD (Computational Fluid Dynamics) are compared with those of EFD (Experimental Fluid Dynamics) and other numerical methods. In addition, the wave-induced drift forces of the fixed/3DOF (Degrees of Freedom) ships are compared with each other (3DOF includes heave, roll and pitch). SWENSE model is proven to be reliable for the predictions of the wave-induced drift forces and motions of ships in waves.
Numerical simulations of water-air-bubble mixed flows around hydrofoil and propeller
Authors: Mao Tianyi , Li Xinyi , Wan Decheng
Published: August 2023

Water-air-bubble mixed flow is a complex multiphase flow usually generated due to the intense interaction between the sailing ship and the free surface[1]. A large number of bubbles scour down along the ship which gather around the propulsion system, making a significant effect on the hydrodynamic performance of propeller and hydrofoil. In this paper, the hydrodynamic performance of two-dimensional hydrofoil and three-dimensional propeller in uniformly mixed water-air-bubble incoming flow is studied by using the Computational Fluid Dynamics (CFD) method. Euler-Euler two-fluid model is used to simulate the uniformly mixed water-air-bubble incoming flow with the open-source CFD software OpenFOAM. The feasibility of numerical simulation is verified by comparing the numerical simulation results with experimental data. On this basis, the changes of physical fields around two-dimensional hydrofoil and three-dimensional propeller caused by water-air-bubble flow under multiple air fraction conditions are discussed. In addition, the differences in dimensionless coefficients are compared between single-phase flow conditions and two-phase flow. Furthermore, the Population Balance Model (PBM) is used in the simulation of two-dimensional hydrofoil to observe the coalescence and break of bubbles.
Propeller-Ice Contact modelling with Peridynamics
Authors: Han Kang , Wang Chao , Yang Zeyu , Guo Chunyu , Wang Chunhui
Published: August 2023

Ice loads pose a significant threat to ice-class propellers in frozen waters, making it crucial to analyse the magnitude of ice loads. However, the complex mechanical properties of ice and its failure process make it challenging to investigate the correlation between ice-propeller contact phenomena and ice loads. This paper uses a PC3 class propeller blade to study the propeller-ice contact process. This study involves developing ice failure and propeller blade models based on ordinary and non-ordinary state-based peridynamics theory and validating them using experimental. Convergence analysis was performed before blade ice loads evaluation. Additionally, we investigate the effect of the pitch angle on the ice-milling process.
Numerical Investigation of the Propulsive Efficiency of a Containership under Load Variation
Authors: Yeh T H , Chen S H , Lin T Y , Chau S W
Published: August 2023

The International Towing Tank Conference (ITTC) suggests that determining the variations of propulsion efficiency can be achieved by model tests that may be costly and inefficient. This is the reason why this paper investigates the variation of propulsion factors under various ship loading conditions by computational fluid dynamics (CFD). This study proposed a non-iterative method for load variation tests that reduced the computational time. The CFD software Star-CCM+ was used to solve the transient free-surface Reynolds-averaged Navier–Stokes equations. To further reduce the computational time, the propeller was modeled using the actuator disk method. The resistance augmentation, wake fraction, and propeller efficiency of a container ship model KCS with propeller KP505 were studied. These values were used to calculate the load variation coefficient of the shaft revolution speed ζN
and load variation coefficient of the delivered power ζP
at full scale. The results showed that as the resistance increased, the rotation rate correspondingly increased to maintain the service speed. As the ship resistance increased, the hull and open water efficiencies decreased, and when the actuator disk model assumed a relative rotative efficiency of 1.0, the quasi-propulsion efficiency also decreased.
Investigating capacitive force sensors with 3D printed flexible structures as dielectric layers
Authors: Lin Chien-Hung , Guo Bo-Yi
Published: August 2023

The utilization of a three dimension (3D) printing for the fabrication of micro-electromechanical system (MEMS) sensors presents various advantages including low cost, customization, simplicity, and speed. This study involved conducting mechanical and electrical analyses on three types of dielectric layer structures using the finite element method. Capacitive force sensors were produced through 3D printing using fused deposition modeling (FDM). The sensitivity and stiffness of the sensors were determined by measuring their capacitance and displacement changes under force using a self-made measurement system. The experimental results indicate that pre-heating the dielectric layer can reduce the hysteresis effects. In terms of more complex structures, stringing phenomena during the printing process can compromise the reliability of the sensor. A suitable dielectric layer structure can be designed based on the measurement range and sensitivity of the sensor. The results of this study demonstrate the potential for additive manufacturing to replace conventional MEMS processes in sensor production. With the advancement of FDM printing technology, it is increasingly feasible to apply 3D printing technology to sensor manufacturing in the future.
On the 𝑝-adic zeros of the Tribonacci sequence
Authors: Bilu Yuri , Luca Florian , Nieuwveld Joris , Ouaknine Joël , Worrell James
Published: August 2023

Let

(

T
n

)

n
∈

Z

(T_n)_{n\in {\mathbb Z}}

be the Tribonacci sequence and for a prime

p
p

and an integer

m
m

let

ν
p

(
m
)

\nu _p(m)

be the exponent of

p
p

in the factorization of

m
m

. For

p
=
2

p=2

Marques and Lengyel found some formulas relating

ν
p

(

T
n

)

\nu _p(T_n)

with

ν
p

(
f
(
n
)
)

\nu _p(f(n))

where

f
(
n
)

f(n)

is some linear function of

n
n

(which might be constant) according to the residue class of

n
n

modulo

32
32

and asked if similar formulas exist for other primes

p
p

. In this paper, we give an algorithm which tests whether for a given prime

p
p

such formulas exist or not. When they exist, our algorithm computes these formulas. Some numerical results are presented.
Modified-operator method for the calculation of band diagrams of crystalline materials
Authors: Cancès Eric , Hassan Muhammad , Vidal Laurent
Published: August 2023

In solid state physics, electronic properties of crystalline materials are often inferred from the spectrum of periodic Schrödinger operators. As a consequence of Bloch’s theorem, the numerical computation of electronic quantities of interest involves computing derivatives or integrals over the Brillouin zone of so-called energy bands, which are piecewise smooth, Lipschitz continuous periodic functions obtained by solving a parametrized elliptic eigenvalue problem on a Hilbert space of periodic functions. Classical discretization strategies for resolving these eigenvalue problems produce approximate energy bands that are either non-periodic or discontinuous, both of which cause difficulty when computing numerical derivatives or employing numerical quadrature. In this article, we study an alternative discretization strategy based on an ad hoc operator modification approach. While specific instances of this approach have been proposed in the physics literature, we introduce here a systematic formulation of this operator modification approach. We derive a priori error estimates for the resulting energy bands and we show that these bands are periodic and can be made arbitrarily smooth (away from band crossings) by adjusting suitable parameters in the operator modification approach. Numerical experiments involving a toy model in 1D, graphene in 2D, and silicon in 3D validate our theoretical results and showcase the efficiency of the operator modification approach.
The Friedrichs operator and circular domains
Authors: Ravisankar Sivaguru , Roy Samriddho
Published: August 2023

The Friedrichs operator of a domain (in

C

n

\mathbb {C}^n

) is closely related to its Bergman projection and encodes crucial information (geometric, quadrature, potential theoretic etc.) about the domain. We show that the Friedrichs operator of a domain has rank one if the domain can be covered by a circular domain via a proper holomorphic map of finite multiplicity whose Jacobian is a homogeneous polynomial. As an application, we show that the Friedrichs operator is of rank one on the tetrablock, pentablock, and the symmetrized polydisc – domains of significance in the study of

μ
\mu

-synthesis in control theory.
The special value 𝑢=1 of Artin-Ihara 𝐿-functions
Authors: Hammer Kyle , Mattman Thomas , Sands Jonathan , Vallières Daniel
Published: August 2023

We study the special value

u
=
1

u=1

of Artin-Ihara

L
L

-functions associated to characters of the automorphism group of abelian covers of multigraphs. In particular, we show an annihilation statement analogous to a classical conjecture of Brumer on annihilation of class groups for abelian extensions of number fields and we also calculate the index of an ideal analogous to the classical Stickelberger ideal in algebraic number theory. Along the way, we make some observations about the number of spanning trees in abelian multigraph coverings that may be of independent interest.
A dedicated cytoplasmic container collects extrachromosomal DNA away from the mammalian nucleus
Authors: Schenkel Laura , Wang Xuan , Le Nhung , Burger Michael , Kroschewski Ruth
Published: August 2023

Mammalian cells express transfected plasmid DNA transiently, but the underlying mechanisms are not well known. Plasmid DNA was found to be captured in the cytoplasmic, (ER)Endoplasmic reticulum-enwrapped exclusome, which clusters both endogenous and exogenous extrachromosomal DNA. Exclusome-envelope formation corresponded to early but not late steps of nuclear-envelope formation. This work suggests that a cell-autonomous genome protection system recognizes, collects, and maintains extrachromosomal DNA in somatic mammalian cells.
Helicobacter pylori–negative mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach: A clinicopathologic analysis
Authors: Gu Sean X , Siddon Alexa J , Huntington Scott F , Jain Dhanpat
Published: August 2023

Objectives

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is historically associated with Helicobacter pylori (HP) infections in more than 80% of patients. However, the incidence of HP-negative MALT lymphoma has been increasing. The clinicopathologic features have not been well studied, and optimal management strategies remain unclear.

Methods

The pathology database was searched for primary gastric MALT lymphomas diagnosed from 2000 to 2017. The clinical data and the slides were reviewed. The cases were divided for analysis into those with a background of chronic gastritis with HP, chronic gastritis without HP, and without either a background of chronic gastritis or HP.

Results

Of 70 gastric MALT lymphoma cases identified, 26 (37% of total) had chronic gastritis and were positive for HP histologically (n = 23) or were HP positive by additional laboratory testing (n = 3). The remaining 44 (63% of total) cases were HP negative by histology. Within the HP-negative cases, 5 (11% of HP-negative cases) showed histologic gastritis while 39 (89% of HP-negative cases) did not have sufficient evidence of gastritis through review of slides (n = 18) or based on available pathology reports (n = 21). The HP-negative cases without gastritis had higher propensities to show a mass lesion on endoscopy compared with HP-positive cases (37.5% vs 11.1%, P = .02) at the initial diagnosis. The immunophenotype and rate of positive B-cell gene rearrangement were not significantly different between the 2 groups. While all HP-positive patients received antibiotics for HP eradication, treatment in the HP-negative group varied among antibiotics, radiation, rituximab, or chemotherapy. Among HP-negative patients with available follow-up, 13 (39%) showed disease recurrence, similar to the recurrence rate in HP-positive patients; however, no individual from either group has died of the disease thus far.

Conclusions

The incidence of HP-negative MALT lymphoma is increasing, and in our practice, it is currently more common than HP-associated MALT lymphomas. The pathophysiology of HP-negative MALT lymphoma without chronic gastritis remains unclear. Follow-up data in our study suggest that the prognosis of these cases is excellent despite varied management modalities.