Hasil untuk "Hydraulic engineering"

Wusheng Zhang, Xiang Zhang, Tian Liu et al.

Pseudoplastic fluids are non-Newtonian fluids and are widely used in chemical production processes. During agitation, a well-mixed cavern will form around the impeller. By contrast, the fluid outside this region is nearly stagnant, which severely limits mixing efficiency. In this study, the standard k-ε model is used to simulate the flow field in a xanthan gum solution agitated by a perturbed six-bent-bladed turbine, with the results validated against a particle image velocimetry experiment. The effects of rotational speed and rheological properties on the flow field are examined. The impeller performance is also studied. The results indicate that under laminar flow conditions, the power number is inversely proportional to the Reynolds number, while the pumping capacity and pumping efficiency increase with increasing Reynolds number and decrease with increasing viscosity. The fluid velocity peaks near the agitator blades. The shear rate displays distinct A-type and M-type distributions across different horizontal planes. Furthermore, when the rotational speed and the xanthan gum mass fraction in the solution reach 540 rpm and 1.25%, respectively, the flow field structure stabilizes with no significant change. Key findings indicate that increasing the rotational speed is more effective than increasing the xanthan gum mass fraction in enhancing global fluid motion and improving mixing efficiency. Under turbulent flow conditions, the formation of two distinct vortices near the top of the tank could reduce stagnant regions in that area. Turbulent kinetic energy is concentrated in the vicinity of the impeller, reaching its peak around the blade tips.

Mikio Nakano, Hironori Takeuchi, Sadahiro Yoshikawa et al.

This paper proposes to refer to the field of software engineering related to the life cycle of dialogue systems as Dialogue Systems Engineering, and surveys this field while also discussing its future directions. With the advancement of large language models, the core technologies underlying dialogue systems have significantly progressed. As a result, dialogue system technology is now expected to be applied to solving various societal issues and in business contexts. To achieve this, it is important to build, operate, and continuously improve dialogue systems correctly and efficiently. Accordingly, in addition to applying existing software engineering knowledge, it is becoming increasingly important to evolve software engineering tailored specifically to dialogue systems. In this paper, we enumerate the knowledge areas of dialogue systems engineering based on those of software engineering, as defined in the Software Engineering Body of Knowledge (SWEBOK) Version 4.0, and survey each area. Based on this survey, we identify unexplored topics in each area and discuss the future direction of dialogue systems engineering.

Mahdi Jaberzadeh Ansari, Ann Barcomb

Although it has been more than four decades that the first components-based software development (CBSD) studies were conducted, there is still no standard method or tool for component selection which is widely accepted by the industry. The gulf between industry and academia contributes to the lack of an accepted tool. We conducted a mixed methods survey of nearly 100 people engaged in component-based software engineering practice or research to better understand the problems facing industry, how these needs could be addressed, and current best practices employed in component selection. We also sought to identify and prioritize quality criteria for component selection from an industry perspective. In response to the call for CBSD component selection tools to incorporate recent technical advances, we also explored the perceptions of professionals about AI-driven tools, present and envisioned.

Kaicheng Huang, Fanyu Wang, Yutan Huang et al.

Advancements in large language models (LLMs) have led to a surge of prompt engineering (PE) techniques that can enhance various requirements engineering (RE) tasks. However, current LLMs are often characterized by significant uncertainty and a lack of controllability. This absence of clear guidance on how to effectively prompt LLMs acts as a barrier to their trustworthy implementation in the RE field. We present the first roadmap-oriented systematic literature review of Prompt Engineering for RE (PE4RE). Following Kitchenham's and Petersen's secondary-study protocol, we searched six digital libraries, screened 867 records, and analyzed 35 primary studies. To bring order to a fragmented landscape, we propose a hybrid taxonomy that links technique-oriented patterns (e.g., few-shot, Chain-of-Thought) to task-oriented RE roles (elicitation, validation, traceability). Two research questions, with five sub-questions, map the tasks addressed, LLM families used, and prompt types adopted, and expose current limitations and research gaps. Finally, we outline a step-by-step roadmap showing how today's ad-hoc PE prototypes can evolve into reproducible, practitioner-friendly workflows.

Yang Zhao, Rui Wang, Jian-Min Zhang

We present an assumed enhanced strain finite element framework for the simulation of tensile fracturing processes in transversely isotropic rocks. Fractures along the weak bedding planes and through the anisotropic rock matrix are treated with distinct enrichment, and a recently proposed dual-mechanism tensile failure criterion for transversely isotropic rocks is adopted to determine crack initiation for the two failure modes. The cohesive crack model is adopted to characterize the response of embedded cracks. As for the numerical implementation of the proposed framework, both algorithms for the update of local history variables at Gauss points and of the global finite element system are derived. Four boundary-value problem simulations are carried out with the proposed framework, including uniaxial tension tests of Argillite, pre-notched square loaded in tension, three-point bending tests on Longmaxi shale, and simulations of tensile cracks induced by a strip load around a tunnel in transversely isotropic rocks. Simulation results reveal that the proposed framework can properly capture the tensile strength anisotropy and the anisotropic evolution of tensile cracks in transversely isotropic rocks.

Cheng-Wei Wang, Shau-Shiun Jan

Precise point positioning (PPP), which is characterized by reliable positioning accuracy and flexibility, has been regarded as a highly promising technique. Precise ephemeris is essential for PPP; however, the conventionally used standard product 3 components have an almost biweekly latency. The multi-global navigation satellite system (GNSS) advanced demonstration tool for orbit and clock analysis (MADOCA), a novel next-generation service, aims to provide real-time correction messages for rapid-convergence PPP in regional areas. Additionally, to ensure seamless navigation during signal-interrupted conditions, an inertial measurement unit (IMU) can be tightly integrated with the motion constraint models. This paper presents a comprehensive analysis of standalone MADOCA-PPP and MADOCA-enhanced tightly coupled PPP/IMU. The approaches were evaluated under multiple scenarios. In suburban regions, the horizontal root mean square error (RMSE) was 0.4 m, with a 95th percentile horizontal error of 0.6 m. In GNSS-challenging environments, the horizontal RMSE was 0.92 m, with a 95th percentile horizontal error of 1.6 m.

YAN Yuliang, DING Hong, ZHANG Jiayue et al.

The Xiliu Songhua River Basin in northeast China was selected as the research object to quantitatively analyze the driving mechanism of climate change and human activities on runoff evolution under the background of global warming and reveal the evolution law of water cycle in cold regions and its eco-hydrological effects. A precipitation phase discrimination model was constructed based on the wet-bulb temperature threshold method, and the Budyko equation was improved by introducing the snowfall ratio. Combined with multi-source methods such as spatial interpolation of meteorological data, Pettitt mutation test, Mann-Kendall trend test, and land use transfer matrix, the synergistic effect of climate factors and underlying surface parameters was systematically evaluated. The annual runoff at Fuyu Station and Jilin Station increased significantly at a rate of 0.12 mm/a and 1.77 mm/a, respectively. The annual average precipitation and annual average snowfall ratio in the basin showed a continuous increasing trend, while the annual average potential evapotranspiration showed a continuous decreasing trend. In terms of spatial distribution, the annual average precipitation and annual average snowfall ratio in the basin showed a trend of less in the north and more in the south, while the annual average potential evapotranspiration showed a pattern of more in the north and less in the south. The contribution rate of precipitation humidification to runoff change reached 57.24%~66.89%, and the contribution rate of human activities was only 4.39%~7.52%. The proposed SR-Budyko coupling framework effectively solved the defects of traditional models in rain and snow phase identification and freeze-thaw energy and water exchange characterization and provided a new theoretical tool for the optimization of water resources systems in cold regions, spring flood disaster prevention and control, and the protection of ecological barriers in northeast China. It has important practical guiding value for water security decision-making in climate change-sensitive areas.

Renan Lima Baima, Tiago Miguel Barao Caetano, Ana Carolina Oliveira Lima et al.

The primary objective is to emphasize the merits of active methodologies and cross-disciplinary curricula in Requirement Engineering. This direction promises a holistic and applied trajectory for Computer Engineering education, supported by the outcomes of our case study, where artifact-centric learning proved effective, with 73% of students achieving the highest grade. Self-assessments further corroborated academic excellence, emphasizing students' engagement in skill enhancement and knowledge acquisition.

Chong Wei, Xiaohua Dong, Yaoming Ma et al.

Study regions: The Wangjiaba (WJB) watershed, located in the upper Huaihe River Basin in China. Study focus: An attributing framework has been proposed combining the Double Mass Curve (DMC) and the Soil and Water Assessment Tools (SWAT) model to identify the contributions of climate variability, Land use (LU) change, and Other Human Activities (OHA) to the variations in runoff-sediment processes within the WJB. New hydrological insights for the region: The studied period was able to be separated into three sub-periods (P1: 1981–1991, P2: 1992–2009, and P3: 2010–2019) using the DMC, and the SWAT model could simulate runoff and Sediment Yields Load (SYL) properly during different sub-periods after calibration. Generally, the runoff, SYL, and Suspended Sediment Concentration (SSC) within the WJB exhibited a decrease trend with a change rate of −1.3 mm a−1, −8.49×104 t a−1, and −0.01 kg m−3 a−1, respectively. Substantially, climate variability decreases runoff, SYL, and SSC from P1 to P3; LU change decreases runoff, SYL, and SSC from P2 to P3; OHA decreases SYL and SSC from P1 to P2, but increases SYL and SSC from P2 to P3. It should be noticed that the OHA has increased the SYL significantly especially over the downstream of WJB from P2 to P3. It is essential to enhance soil erosion prevention measures in the future under the background of global climate change.

Lin Song, Yang Yu, Jianxing Yu et al.

High-rise buildings are inherently vulnerable to substantial wind-induced forces. The increasing complexity of building designs has posed challenges in calculating wind loads, while traditional methods involving physical models have proven to be intricate and time-consuming. In order to overcome these obstacles, this paper investigates a theoretical methodology aimed at streamlining the computation of wind loads. In the initial theoretical exploration, a simplified mathematical model based on Green’s function is introduced to take into account the interaction between wind loads and building geometry, while the model is not user-friendly and difficult to solve for complex polygonal buildings. To overcome this challenge, the study incorporates numerical simulations to extend the ideas and refine the methodology. To simplify the problem from a three-dimensional to a two-dimensional context, a bold tangential field assumption is made, assuming the wind pressure distribution remains similar across horizontal sections at different heights. The Schwarz–Christoffel formulation is then employed to facilitate the transformation. By integrating Green’s functions and conformal mapping to solve potential flow problems beyond the boundary layer, a comprehensive mathematical derivation is established. The above broadens the applicability of the mathematical theory and provides a new direction for estimations of high-speed wind load on buildings.

Kazuki Sugiyama, Yoshihiro Kubota, Osamu Mochizuki

We investigated the wing vein network topology in fruit flies and observed that the posterior cross vein (PCV) disrupts the symmetry of the entire network. The fluidic engineering function of this vein's disposition remains unexplored although the wing vein network is known to transport blood. We examined the fluid mechanical effects of the PCV's disposition on this blood-transporting network through numerical simulations involving the removal and rearrangement of the vein, avoiding impractical physical manipulation. We characterised the geometry of each wing membrane cell, a portion of the wing membrane surrounded by a group of veins, by determining the ratio of its surface area to the contact area with the veins. We considered this ratio in association with the flow velocities of seeping water from the blood within the veins to the membrane and evaporating water from the membrane, based on the mass conservation law. We observed that the division of a membrane cell by the PCV maximises the ratio of the areas in the divided cell on the wing-tip side by virtually shifting this vein's connections in our geometric membrane model. We derived blood flow rate and pressure loss within the venous network from their geometry, using an analogy of the venous network with a circuit consisting of hydraulic resistors based on Kirchhoff and Ohm's laws. The overall pressure loss in the network decreased by 20% with the presence of the PCV functioning as a paralleled hydraulic resistor. By contrast, any other cross-vein computationally arranged on another membrane cell as the PCV's substitution did not exhibit a larger reduction in the pressure loss. Overall, our numerical analyses, leveraging geometry and a circuit analogy, highlighted the effects of the PCV's presence and position on the blood-transporting vein network.

Hanna Abi Akl

The "Information Retrieval in Software Engineering (IRSE)" at FIRE 2023 shared task introduces code comment classification, a challenging task that pairs a code snippet with a comment that should be evaluated as either useful or not useful to the understanding of the relevant code. We answer the code comment classification shared task challenge by providing a two-fold evaluation: from an algorithmic perspective, we compare the performance of classical machine learning systems and complement our evaluations from a data-driven perspective by generating additional data with the help of large language model (LLM) prompting to measure the potential increase in performance. Our best model, which took second place in the shared task, is a Neural Network with a Macro-F1 score of 88.401% on the provided seed data and a 1.5% overall increase in performance on the data generated by the LLM.

Alessio Dallabona, Mogens Blanke, Henrik C. Pedersen et al.

Wind energy is the leading non-hydro renewable technology. Increasing reliability is a key factor in reducing the downtime of high-power wind turbines installed in remote off-shore places, where maintenance is costly and less reactive. Defects in the pitch system are responsible for up to 20% of a wind turbine downtime.Thus, monitoring such defects is essential for avoiding it. This paper presents a generic assessment of the diagnosis capabilities in hydraulic pitch systems, which are used in high-power wind turbines. A mathematical model of the non-linear system dynamics is presented along with a description of the most frequent faults that occur. Structural analysis is used to assess which defects can be detected in the pitch system. The structural properties are furthermore explored to investigate the possibility of reducing the amount of sensors without compromising the fault diagnosis capabilities. Robustness to model uncertainty is finally addressed and generic principles for estimating the detectable magnitude of wear and tear are presented.

Brian S. Mitchell

Cloud compute adoption has been growing since its inception in the early 2000's with estimates that the size of this market in terms of worldwide spend will increase from \$700 billion in 2021 to \$1.3 trillion in 2025. While there is a significant research activity in many areas of cloud computing technologies, we see little attention being paid to advancing software engineering practices needed to support the current and next generation of cloud native applications. By cloud native, we mean software that is designed and built specifically for deployment to a modern cloud platform. This paper frames the landscape of Cloud Native Software Engineering from a practitioners standpoint, and identifies several software engineering research opportunities that should be investigated. We cover specific engineering challenges associated with software architectures commonly used in cloud applications along with incremental challenges that are expected with emerging IoT/Edge computing use cases.

Jocelyn Ahmed Mazari, Antoine Reverberi, Pierre Yser et al.

In this work, we propose a built-in Deep Learning Physics Optimization (DLPO) framework to set up a shape optimization study of the Duisburg Test Case (DTC) container vessel. We present two different applications: (1) sensitivity analysis to detect the most promising generic basis hull shapes, and (2) multi-objective optimization to quantify the trade-off between optimal hull forms. DLPO framework allows for the evaluation of design iterations automatically in an end-to-end manner. We achieved these results by coupling Extrality's Deep Learning Physics (DLP) model to a CAD engine and an optimizer. Our proposed DLP model is trained on full 3D volume data coming from RANS simulations, and it can provide accurate and high-quality 3D flow predictions in real-time, which makes it a good evaluator to perform optimization of new container vessel designs w.r.t the hydrodynamic efficiency. In particular, it is able to recover the forces acting on the vessel by integration on the hull surface with a mean relative error of 3.84\% \pm 2.179\% on the total resistance. Each iteration takes only 20 seconds, thus leading to a drastic saving of time and engineering efforts, while delivering valuable insight into the performance of the vessel, including RANS-like detailed flow information. We conclude that DLPO framework is a promising tool to accelerate the ship design process and lead to more efficient ships with better hydrodynamic performance.

Isnan Fauzan Akrom, Muhammad Fauzi

The 2020 drought led to a reduction in the water supply of the Citarum cascade reservoirs (Saguling, Cirata, and Juanda) due the lowering intensity of rainfall in the catchments of the three reservoirs. Rainfall in late 2020 through February 2021 was much lower than the predicted and historical averages. This caused the water level of the Citarum cascade reservoirs fell to be below normal at the end of December 2020. To meet the water demand, an increase in inflow enhancement is needed, hence the implementation of Weather Modification Technology (WMT) which was carried out on March 12th - April 21st, 2021 in the Citarum watershed, West Java Province. WMT is applied for increasing or decreasing the amount of rainfall by intervening in the cloud growth process, which is carried out by seeding NaCl powder on clouds using an airplane. The purpose of monitoring and evaluation (M&E) of WMT implementation is to collect data, analyze, and evaluate the hydrological conditions of the Citarum cascade reservoirs during WMT implementation. The purpose of M&E is to assess the success of additional reservoir volume due to rainfall during WMT implementation. The M&E is conducted by collecting daily data of the rainfall, water level, and hydrological data of the reservoirs. The data collected each day is used as the basis for the seeding strategy on that day. After the WMT implementation activities are completed, an evaluation of the overall WMT implementation results is continued, which includes analyzing rainfall data, river water level, as well as the inflow, volume, and water level of the reservoir. The results of this study show that WMT implementation could not raise the water level of the three reservoirs to the Normal Operating Limit, but it has succeeded in increasing the reservoir volume by approximately 270 million m3 for Saguling, 201 million m3 for Cirata, and 59 million m3 for Juanda.

LIAO Yu, ZHAO Lei

Miroslav Vořechovský

The paper presents a new efficient and robust method for rare event probability estimation for computational models of an engineering product or a process returning categorical information only, for example, either success or failure. For such models, most of the methods designed for the estimation of failure probability, which use the numerical value of the outcome to compute gradients or to estimate the proximity to the failure surface, cannot be applied. Even if the performance function provides more than just binary output, the state of the system may be a non-smooth or even a discontinuous function defined in the domain of continuous input variables. In these cases, the classical gradient-based methods usually fail. We propose a simple yet efficient algorithm, which performs a sequential adaptive selection of points from the input domain of random variables to extend and refine a simple distance-based surrogate model. Two different tasks can be accomplished at any stage of sequential sampling: (i) estimation of the failure probability, and (ii) selection of the best possible candidate for the subsequent model evaluation if further improvement is necessary. The proposed criterion for selecting the next point for model evaluation maximizes the expected probability classified by using the candidate. Therefore, the perfect balance between global exploration and local exploitation is maintained automatically. The method can estimate the probabilities of multiple failure types. Moreover, when the numerical value of model evaluation can be used to build a smooth surrogate, the algorithm can accommodate this information to increase the accuracy of the estimated probabilities. Lastly, we define a new simple yet general geometrical measure of the global sensitivity of the rare-event probability to individual variables, which is obtained as a by-product of the proposed algorithm.

WANG Kun, CHEN Lin, PANG Danbo et al.

【Objective】 Precipitation and evapotranspiration are two important parameters required in hydrological modelling and water resource management. In this paper, we analyzed their temporal variation in the arid area in central Ningxia province. 【Method】 The analysis was based on precipitation and monthly average temperature measured from 1969 to 2020 from six meteorological stations across the area. Spatiotemporal variation in the precipitation and net precipitation (the difference between precipitation and evapotranspiration) was calculated using the Koichiro Takahashi's evapotranspiration formula, climate trend method, Mann-Kendall mutation test and the wavelet cycle analysis. 【Result】 ① The precipitation in northwest and southeast of the area differed considerably, with the precipitation in the former and the latter being 188.0 mm and 304.1 mm, and their associated net precipitation being 17.8 mm and 58.9 mm, respectively. ② Rainfall in the area falls mainly in summer, accounting for 57% of the annual precipitation, while precipitation in the winter is the least, accounting for only 3% of annual precipitation. The net precipitation in spring and winter is lower than that in other seasons. ③ Interannual variation in net precipitation has been in a transition from fluctuations to continued drying in the studied period. The extreme rainfalls were mainly in the southeast, and the net precipitation in the northwest was more abundant before 2013 than after 2013. ④ Trend analysis shows that the annual precipitation and net precipitation in the southeast have increased significantly at 1.539 mm/a and 0.467 mm/a, respectively. In contrast, the precipitation in the northwest had increased at 0.647 mm/a, while the net precipitation had been decreasing at 0.073 mm/a though not at a significant level. Mutation analysis showed an abrupt precipitation change in 2010. ⑤ Precipitation and net precipitation in the studied area showed periodicities of 9, 12~13, 40 a, with their associated oscillating periods being 6, 9 and 25 a, respectively. The net precipitation varied largely, having a greater impact on agriculture and animal husbandry. 【Conclusion】 Precipitation and net precipitation in the southeast is more abundant than in the northwest of the studied area. The magnitude of seasonal annual precipitation and net precipitation are ranked in the order of summer>autumn>spring>winter. Precipitation and net precipitation in the studied area have been increasing over the studied period.

David I. Ketcheson, Manuel Quezada de Luna

We investigate the numerical artifact known as a carbuncle, in the solution of the shallow water equations. We propose a new Riemann solver that is based on a local measure of the entropy residual and aims to avoid carbuncles while maintaining high accuracy. We propose a new challenging test problem for shallow water codes, consisting of a steady circular hydraulic jump that can be physically unstable. We show that numerical methods are prone to either suppress the instability completely or form carbuncles. We test existing cures for the carbuncle. In our experiments, only the proposed method is able to avoid unphysical carbuncles without suppressing the physical instability.