bluuebunny/crossref_metadata_2025_split huggingface dataset:
The performance of smallholder dairy farms in West Java
Authors: Purwantini T B , Saliem H P , Ariningsih E , Erwidodo  , Anugrah I S , Suryani E , Irawan A R , Hetherington J B 
Published: November 2021

Abstract
Small farmers dominate dairy farming in Indonesia, and the average productivity is low. An understanding of the performance of farmers and dairy farming businesses is needed to formulate policies for developing small-scale dairy farms. This study aims to provide information about the performance of dairy farms and recommend policies or measures to develop smallholder dairy farms in West Java. The data used in this paper is taken from the IndoDairy Smallholder Household Survey (ISHS) database, covering 600 dairy farm households selected randomly in Bandung, Garut, Cianjur, and Bogor Districts. Data collection took place between August and September 2017. A purposive and proportional random sampling method was utilized to select the samples. Data were analyzed by using descriptive statistical analysis. The results show that the main income activity of households (80%) was dairy farming. In addition to dairy farming, households received 10% of their income from off-farm activities, 8% from horticultural production, 2% from other livestock, and 1% from crop production. On average, dairy herd sizes were 5.6 cows per farm, of which the highest found in Bogor (7.7) and lowest in Garut (3.1). The results also show that milk production per cow ranged from 14.1 to 15.2 liters/day/lactating cows, with an average of 14.9 liters/day/lactating cows. Policies and efforts to increase milk production, productivity, and quality of fresh milk through improving feed technology and better dairy farming management are critically important to increasing smallholder dairy farmers’ income in Indonesia, especially in West Java.
Integrating tea and tourism: a potential sustainable livelihood approach for Indonesia tea producer central area
Authors: Sita K , Aji T M , Hanim W 
Published: November 2021

Abstract
The social changes within society with regard to tea are widespread in Indonesia and today are experienced as tourism, where a part of many tourist activities, whereby local tea traditions, cultures, services and attractions are experienced. Indonesia as both tea-producing and tea-consuming country has high potential to integrate with tourism to increase the sustainability of community livelihood. This study used a sustainable livelihood approach in a systematic framework to examine the relationships between tea and tourism, as well as enriched the interviews of tourist actors and 203 tourists with experiences of visiting the tea tourism destinations. This study finding that there has been an increase of diversity of livelihoods of the people around the tea plantations where have been developed into tourism. Corporate social responsibility provides a further opportunity in sustainable tea tourism development. Increasing services satisfaction of the tea tourists is one of the most important ways to increase the revisit intention. Creating a mutual partnership synergy can cover the lack of resources and competencies in tea and tourism integration development. For practical implications in the future are the important to enlarge integration between tea and tourism, build partnership, stimulate more local participation, and increase local benefits as their ways of life.
A compensation scheme applied on wind turbine blade pitch control for the reduction of non-torque main shaft loads
Authors: Balakrishna R , Xing Y 
Published: November 2021

Abstract
It has been well established that non-torque main shaft loads influence the internal drive train loads. This paper proposes a scheme that compensates for non-torque loads in the blade pitch controller. The compensation scheme is implemented on a dynamic model developed in FAST/Simulink. Three wind conditions of 8, 11.4 and 20 m/s are examined. The dynamic analysis of the bending moment in the low-speed shaft showed a reduction in bending moment by 3 % for the rated wind speed (11.4 m/s) and 1.8 % for the above-rated wind speed (20 m/s), highlighting the effectiveness of the proposed scheme. However, a reduction in bending moment also slightly decreased the shaft’s speed by 2.3 % and 0.5 %, respectively. Similarly, the turbine power was decreased by 9 % and 1 %, respectively. In comparison, further gain scheduling within the compensation scheme reduces the power loss to as low as 0.3 %. The 2 to 3 % reduction in the low-speed shaft bending moment can significantly influence the drive train loads and easily outweigh any loss resulting in the shaft rotational speed and turbine power. Thus, this paper shows that using bending moment error as feedback within the compensation scheme positively affects the low-speed shaft’s bending moment with the eventual potential of reducing drivetrain loads.
Aerodynamic study of a suspension bridge deck by CFD simulations, wind tunnel tests and full-scale observations
Authors: Kusano I. , Cheynet E. , Jakobsen J. B. , Snæbjörnsson J. 
Published: November 2021

Abstract
Assessing the aerodynamic characteristics of long-span bridges is fundamental for their design. Depending on the terrain complexity and local wind conditions, episodes of large angles of attack (AoA) of 15° may be observed. However, such large AoAs ( above 10°) are often overlooked in the design process. This paper studies the aerodynamics properties of a flow around a single-box girder for a wide range of AoAs, from –20° to 20°, using numerical simulations. The simulations are based on a 2D unsteady Reynolds-averaged Navier–Stokes (URANS) approach using the k − ω SST turbulence model with a Reynolds number of 1.6 × 105. Numerically obtained aerodynamic static coefficients were compared to wind tunnel test data. The CFD results were generally in good agreement with the wind tunnel tests, especially for small AoAs and positive AoAs. More discrepancies were observed for large negative AoA, likely due to the limitation of modelling 3D railings with 2D simulations. The simulated velocity deficit downstream of the deck was consistent with the one measured in full-scale using short-range Doppler wind lidar instruments. Finally, the Strouhal number from the CFD simulations were in agreement with the value obtained from the full-scale data.
Determining reservoir parameters with nonisothermal real gas flow
Authors: Aminev D A , Kravchenko M N 
Published: November 2021

Abstract
Creation and developing methods of determining gas reservoir properties are one of the most important gas hydrodynamics tasks as production project efficiency and reservoir exploitation depend upon layer properties knowledge. Nonstationary gas hydrodynamics investigations are one of the base well and layer researching methods. Results of these investigations are interpreted based on solving of linear isothermal gas flow equation. The current investigation describes the nonstationary gas hydrodynamic survey results interpretation algorithm, which is based on nonlinear equations system solving. The system consists of nonlinear nonisothermal real gas flow and energy equations accounting well influence, Joule-Thompson and adiabatic expansion effects. Integro-interpolation and iteration finite methods were used for creating their own numerical algorithm. Numerical programs allow solving as direct as inverse gas flow tasks in the cylindrical layer. For verification of inverse task solution, the survey interpretation results from the real gas field were paralleled with currently methods results and showed sufficient accuracy. The described method allows to interpret survey gas hydrodynamic results accounting real gas and porous matrix properties, and well influence to enhance integrity and precision reservoir properties estimation.
CFD investigation of internal elbow pipe flows in laminar regime
Authors: Taibi R , Yin G , Ong M C 
Published: November 2021

Abstract
Elbow pipes are crucial parts of many fluid transport systems in the oil and gas industry. The curved shape of such pipes induces centrifugal forces on the internal flow, ultimately affecting the flow velocity and creating pressure differences within the elbow. The present study aims to investigate the effects of the curvature ratio of an elbow pipe on the internal pipe flow using three-dimensional numerical simulations. For laminar flows, the simulations are based on four Reynolds numbers ranging from 200 to 2000 and three curvature ratios of Ro=5.6, 11.2 and 22.4. A mesh convergence study is carried out for 3 meshes with increasing resolution. The results based on the optimal mesh is then compared with the published experimental and numerical results for validation. Once the validation is confirmed, further simulation and analysis are performed for each combination of curvature ratio and Reynolds number. The results reveal that there is flow separation due to the centrifugal forces induced by the curved shape. It is also shown that secondary flows consisting of symmetrical helical vortices called Dean vortices are generated. The intensity of this secondary flow is shown to increase with the increasing Dean number.
Duplex steel welding in artic conditions – Correlation of welding parameters in relation to HISC
Authors: Czarnacki Z , Xing Y 
Published: November 2021

Abstract
Duplex steel is an austenitic-femtic steel alloy commonly used in the offshore and subsea oil and gas industry. Duplex steel provides a unique combination of good mechanical properties and corrosion resistance in sweet and sour hydrocarbon environment, as well as in seawater. However, the combination of tensile loading, post-weld residual stresses, cathodic protection and other factors related to subsea implementation significantly increase the probability of hydrogen induced stress cracking (HISC). This paper aims to find a relationship between the formation of residual stresses and the imperfection of the welding process carried out on Duplex steel in extremely cold conditions. Based on a finite element (FE) welding transient simulation from a thermal perspective, the correlation between the welding parameters and heat distribution is established and analysed when the welding takes place in the cold arctic conditions. Pearson parameter correlation analysis method will be used to investigate the impact of extreme ambient temperatures on the welding process. The results and conclusions provide a solid foundation for welding process optimization in connection with HISC.
Hydrodynamic model of an oil spill on the Earth’s surface and the use of expert technologies in its implementation to assess pollution methods
Authors: Lokhov A S , Gubaidullin M G , Korobov V B 
Published: November 2021

Abstract
A volumetric model of accidental oil spills on the land surface was developed, based on numerical methods for solving hydrodynamic equations, and taking into account the processes of oil spreading over the surface, its filtration into the soil and evaporation into the atmosphere. Based on the results of calculations using the hydrodynamic model for the most probable scenarios of oil spills, it is possible to obtain an estimate of the spatial-temporal scale of the spill, which, together with data on the terrain and the presence of water bodies, is the input data for the expert model. Based on the joint use of the hydrodynamic model of the oil spill and expert technologies, the territory of the Nenets Autonomous Okrug and the South Khylchuyu-Varandey oil pipeline were zoned in more detail. It makes it possible to predict the scale and areas most susceptible to negative impact in the event of an accidental oil spill, and to make the necessary decisions for the location of the spill response facilities, as well as the facilities themselves, already at the stage of selection and design of the pipeline route.
A practical design procedure for initial sizing of heaving point absorber wave energy converters
Authors: Jouybari M B , Xing Y 
Published: November 2021

Abstract
Designing a wave energy converter with the proper size has always been challenging since it is a trade-off between many factors including cost, practicality, and energy output. In this paper a practical design procedure for sizing of heaving point absorbers wave energy converters is presented. Size can be represented by the body volume. Budal power bounds are deployed to obtain the body volume and annual mean absorbed power of the wave energy converter. Budal power bounds are determined for each sea state. Aiming a specific power capture ratio, several sets of design sea states with related design volume and annual mean absorbed power are defined. With the design objective of maximizing the ratio of mean power to submerged volume, and considering suitable design constraints, the best size is obtained. The proposed procedure will be then deployed for a case study and the design will be compared with an existing similar point absorber. The results show that the mean absorbed power does not depend on the size but is a function of selected sea states. Furthermore, the comparison study reveals that the proposed design procedure yields reasonable power characteristics.
A 2D model for the study of equilibrium glide paths of UiS Subsea Freight-Glider
Authors: Ahmad U N , Xing Y 
Published: November 2021

Abstract
A planar mathematical model for the analysis of equilibrium glide paths of the UiS subsea freight-glider (USFG) is presented. The model is developed using Simscape Multibody in MATLAB/Simulink to study the ever-changing dynamics of the glider. Motion along the heave and pitch direction is regulated by two separate PID controllers. Controllers are tuned for the optimal bandwidth and phase margin to provide the system with ideal gains which satisfy the system requirements. A wide-ranging sensitivity investigation is carried out on the USFG by changing the two key variables, pump flow rate and ballast fraction. The results reflect the advantages of using higher flow capacity and ballast fraction, which should be preferred according to the application, provided if there are no space and weight restrictions. Finally, different glide paths were simulated to observe that, controller gains obtained from the linear model can be improved to acquire better performance in terms of robustness and stability of the system.
Global analysis of floating offshore wind turbines with shared mooring system
Authors: Munir H , Lee C F , Ong M C 
Published: November 2021

Abstract
Floating wind turbines (FWTs) with shared mooring systems can be one of the most cost- effective solutions in reducing mooring costs. First, the static configuration of a shared line is estimated using the elastic catenary equation. The present study investigates the global responses of two FWT with a shared mooring system. Two shared mooring configurations with different horizontal distances between the FWTs are considered. In the first configuration, the FWTs are placed 750m apart; and in the second configuration, they are placed 1000m apart. Two different environmental conditions (ECs) are used to simulate the global responses of the system in time domain. The shared mooring line results in higher extreme motions in surge and sway (degree of freedoms) DOFs due to the reduction of mooring restoring stiffness. The lower mooring restoring stiffness can be attributed to the reduction of one seabed anchoring point for each FWT as compared to a single FWT with three anchors installed. In the rotational DOFs, the shared mooring line configurations result in slight mean offset in each direction and significant increase in the motion standard deviations. This is caused by the reduced mooring stiffness associated with the change in platform orientation.
Safety related study of Expanding Pin systems application in lifting and drilling equipment within Construction, Offshore, and Marine sectors
Authors: Karlsen Ø , Lemu H G 
Published: November 2021

Abstract
A questionnaire-based survey has been performed among original equipment manufacturers (OEMs), sub-suppliers, engineering companies, end-users, service & maintenance, and “others”, as part of an investigation to clarify their relationship to expanding pin system, compared to standard, cylindrical pins. In addition, a short literature study on onshore cranes is conducted. The survey is based on 9 questions about safety for personnel and machine, breakage, and wear of pins and supports, and installation and retrieval easiness of pins. The analysis of the responses indicates that safety for personnel and machines/equipment is regarded mainly as either “Important” or “Crucial and decisive”, and that the expanding pin solution is regarded as “better” or “equal” compared to the standard, cylindrical pin, both for “safety level”, “risk for breakage of pin & support”, “tear & wear on pin & support” and “installation and retrieval time”.
Code for calculating wave technology of thermal-gas-chemical formation treatment for oil recovery enhancement
Authors: Kravchenko M N , Kroshilin V E , Dieva N N 
Published: November 2021

Abstract
Transition to the development of hard-to-recover hydrocarbons, including in regions the far north, is fraught with difficulties in using classical technologies development. This is due to the low porosity and permeability of the reservoirs, high viscosity of the formation fluid and the manifestation of abnormal (non-Newton) properties of hydrocarbon fluids. In this regard, for more than ten years, pilot field research (FPI) in terms of the selection and optimization of technologies for collectors of complex structures. Since 2011, at the departments of the underground hydromechanics of Gubkin Russian State University of Oil and Gas (NRU) and gas wave dynamics of the Lomonosov Moscow State University, research is underway on the use of thermogas-chemical method with an injection of a binary mixture to stimulate the inflow. Since 2011, several settlement codes of different levels were created, which allowed carrying out support (pilot) in various fields. Based software products managed to evaluate the characteristics in the chemical reaction zone decomposition of the working chemical composition, evaluate safe regimes, excluding damage to the wellbore and assess the prolongation of the effect. Published more than 20 works (including patents) with the participation of the authors. Since 2019 the mathematical model is significantly complicated: the multiphase and non-isothermality of the process, non-uniformity of the flow. Currently established generalizing code, in the mathematical model of which is additionally taken into account different compressibility of phases and rheological properties of fluids, which allows more fine-tune the computational code for the type of a specific field, taking into account its geological features and damage to the bottomhole zone in the previous stages of development.
Multi-objective optimization and analysis for laser beam cutting of stainless steel (SS304) using hybrid statistical tools GA-RSM
Authors: Tura A D , Mamo H B , Desisa D G 
Published: November 2021

Abstract
A laser beam machine is a non-traditional manufacturing technique that uses thermal energy to cut nearly all types of materials. The quality of laser cutting is significantly affected by process parameters. The purpose of this study is to use a genetic algorithm (GA) in conjunction with response surface approaches to improve surface roughness in laser beam cutting CO2 with a continuous wave of SS 304 stainless steel. The effects of the machining parameters, such as cutting speed, nitrogen gas pressure, and focal point location, were investigated quantitatively and optimized. The tests were carried out using the Taguchi L9 orthogonal mesh approach. Analysis of variance, main effect plots, and 3D surface plots were used to evaluate the impact of cutting settings on surface roughness. A multi-objective genetic algorithm in MATLAB was used to achieve a minimum surface roughness of 0.93746 μm, with the input parameters being 2028.712 mm/m cutting speed, 11.389 bar nitrogen pressure, and a focal point position of - 2.499 mm. The optimum results of each method were compared, as the results the response surface approach is less promising than the genetic algorithm method.
Characterization of acoustic emission signals under 3-point bending test
Authors: Nguyen N B G , Lemu H G , Gabrielsen O , El-Thalji I 
Published: November 2021

Abstract
This paper summarizes a master’s thesis project which explored whether the characteristics of Acoustic Emission Testing (AET) signals can be used to detect yielding in steel samples undergoing a three-point bending test. A subset of existing data from a three-point bending test was exported and used as input. Data was processed by utilizing and developing tools to visualize and analyse the signal characteristics, primarily through a parameter-based approach. Signals were visualized, and parameters were optimized to identify and classify signal types. According to the obtained results, some limitations on classification were experienced due to the length of the hit data recorded. Though the work reported in this article lead to a reliable method for detecting yielding, the developed algorithms were not successful in identifying characteristics that could be used to detect yielding.
Bending capacity of multi-layered FRP pipelines during offshore installation
Authors: Pavlou Dimitrios 
Published: November 2021

Abstract
The Fiber Reinforced Polymeric (FRP) pipelines have higher strength than steel, and excellent fatigue behavior and corrosion resistance. Because of their superior performance in mechanical loads and corrosive environment, they are a good choice for offshore applications. Since FRP materials are anisotropic and the pipelines are multilayered, the calculation of stresses is difficult. Stress analysis can be performed numerically with the aid of commercial software packages. However, the numerical solutions are approximate and the parametric study is problematic. In the present work, an analytical solution for bending stress calculation of multilayered FRP pipelines during offshore installation is presented. Typical examples are solved and bending capacity of multilayered FRP pipelines versus the fiber orientation angle and number of layers is provided and discussed.
Subsea FRP pipeline performance in external pressure: Failure and external pressure-induced buckling
Authors: Pavlou Dimitrios 
Published: November 2021

Abstract
The Subsea pipelines are subjected to high hoop stresses due to the hydrostatic pressure. When the internal pressure of the liquid has a higher value than the external hydrostatic one, there is a balance of the tensile and compressive stresses. However, during the offshore installation, the subsea pipelines are empty and the compression due to the hydrostatic pressure of the sea is predominant. High compressive stresses in FRP pipelines can cause failure or buckling. In the present work, an investigation of the external pressure-induced failure and buckling is carried out. Analytical formulae and results are provided and discussed.