Search Results (146)

This study presents a computational fluid dynamics (CFD) analysis of the performance of counter-rotating impeller systems in mixed-flow pumps. The analysis evaluates the impact of varying rotor velocity ratios and blade geometry on head rise, efficiency, and hydraulic losses. Through detailed CFD simulations, the counter-rotating system demonstrates significant improvements in head and efficiency at low flow rates, with model B achieving up to 20% higher efficiency near the best efficiency point (BEP). However, increased hydraulic losses offset efficiency gains at higher flow rates. While the findings provide valuable insights for optimizing the design of counter-rotating systems in mixed-flow pumps, experimental validation is needed to confirm the results and ensure real-world applicability. The study lays the groundwork for future work in refining counter-rotating pump designs to minimize hydraulic losses and slippage. Full article

Background and Objectives: Seminoma is the most common solid malignant tumour in young men. Clear-cell kidney carcinoma is the most common malignancy of the genitourinary tract. However, the synchronous occurrence of both of these tumours is rare. Case presentation: We present the case of a 36-year-old patient who presented to a medical facility at the end of 2019 with an enlarged right testicle. A unilateral orchofuniculectomy was performed, and a mass measuring 30 cm was removed. During histological examination, testicular seminoma pT2, R0, was diagnosed. An abdominal computed tomography (CT) scan showed a 6.4 cm × 6.8 cm × 6.7 cm tumour in the right kidney and a metastatic-like lesion in the right adrenal gland. A right nephrectomy and an adrenalectomy and paraaortic and paracaval lymphadenectomies were performed. A histological evaluation confirmed the presence of clear-cell renal carcinoma pT2aR0 G2, adrenal hyperplasia, and seminoma metastases in the removed lymph node. Chemotherapy with a Bleomycin, Etoposide, and Cisplatin (BEP) regimen was carried out. Three years after the last cycle of chemotherapy, a follow-up CT scan showed metastases in the left kidney, the right ischium, and the right lung. A well-differentiated clear-cell carcinoma G1 of the left kidney and metastasis of clear-cell carcinoma G2 in the right ischium were confirmed after the biopsy, and no tumour lesions were found in the lung tissue specimen. Treatment with targeted therapy with Sunitinib was started because the risk was favourable according to the Heng criteria. Genetic testing was performed, and the following genes were analysed: VHL, BAP1, CHEK2, FH, MET, MUTYH, APC, and STK11. The testing did not reveal any pathogenic or potentially pathogenic mutations or sequence changes of unknown clinical significance in the genes analysed. Conclusions: According to the authors, the occurrence of synchronous primary tumours is linked to one’s genetic predisposition. DNA sequencing of tumour tissue could provide more information on the corresponding aetiopathogenesis. Full article

This study addresses the critical need for standardizing building information modeling (BIM) execution plans (BEPs) in the architecture, engineering, construction, and operations (AECO) sector. Through the analysis of 36 BEP documents from international organizations, we have identified crucial components and put forth a comprehensive framework with the objective of improving digital transformation and collaboration in intricate construction projects. This study utilizes scientometric analysis to chart the development of BEP standards and incorporates empirical data from industry surveys to verify the suggested framework. The results of our research emphasize the advantages of using standardized building execution plans (BEPs) to decrease inefficiencies and enhance project outcomes. This makes a substantial contribution to the field of building information modeling (BIM) implementation. Full article

Although the maximum carboxylation rate (V_cmax) is an important parameter to calculate the photosynthesis rate for the terrestrial biosphere models (TBMs), current models could not satisfactorily estimate the V_cmax of a crop because the V_cmax is always changing during crop growth period. In this study, the Breathing Earth System Simulator (BESS) and light response curve (LRC) were combined to invert the time-continuous V_m25 (V_cmax normalized to 25 °C) using eddy covariance measurements and remote sensing data in five maize sites. Based on the inversion results, we propose a Two-stage linear model using leaf age to estimate crop V_m25. The leaf age can be readily calculated from the date of emergence, which is usually recorded or can be readily calculated from the leaf area index (LAI), which can be readily obtained from high spatiotemporal resolution remote sensing images. The V_m25 used to calibrate and validate our model was inversely solved by combining the BESS and LRC and using eddy covariance measurements and remote sensing data in five maize sites. Our Two-stage linear model (R² = 0.71–0.88, RMSE = 5.40–7.54 μmol m⁻² s⁻¹) performed better than the original BESS (R² = 0.01–0.67, RMSE = 13.25–18.93 μmol m⁻² s⁻¹) at capturing the seasonal variation in the V_m25 of all of the five maize sites. Our Two-stage linear model can also significantly improve the accuracy of maize gross primary productivity (GPP) at all of the five sites. The GPP estimated using our Two-stage linear model (underestimated by 0.85% on average) is significantly better than that estimated by the original BESS model (underestimated by 12.60% on average). Overall, our main contributions are as follows: (1) by using the BESS model instead of the BEPS model coupled with the LRC, the inversion of V_m25 took into account the photosynthesis process of C4 plants; (2) the maximum value of V_m25 (i.e., PeakV_m25) during the growth and development of maize was calibrated; and (3) by using leaf age as a predictor of V_m25, we proposed a Two-stage linear model to calculate V_m25, which improved the estimation accuracy of GPP. Full article

The issue of carbon emissions can be addressed through environmentally friendly technological innovations, which contribute to the journey towards achieving net-zero emissions (NZE). The electrification of transportation by converting internal combustion engine (ICE) motorcycles to converted electric motorcycles (CEM) directly reduces the number of pollution sources from fossil-powered motors. In Indonesia, numerous government regulations support the commercialization of the CEM system, including the requirement for conversion workshops to be formal entities in the CEM process. Every CEM must pass a test to ensure its safety and suitability. Currently, the CEM testing process is conducted at only one location, making it inefficient and inaccessible. Therefore, most conversion workshops in Indonesia need to take investment steps in procuring CEM-type test tools. This research aims to determine the best alternative from several investment alternatives for CEM-type test tools. In selecting the investment, three criteria are considered: costs, operations, and specifications. By using the investment decision-making model, a hierarchical decision-making model is obtained, which is then processed using the analytical hierarchy process (AHP) and the technique for order of preference by similarity to the ideal solution (TOPSIS). Criteria are weighted to establish a priority order. The final step involves ranking the alternatives and selecting Investment 2 (INV2) as the best investment tool with a relative closeness value of 0.6279. Investment 2 has the shortest time process (40 min), the lowest electricity requirement, and the smallest dimensions. This research aims to provide recommendations for the best investment alternatives that can be purchased by the conversion workshops. Full article

The article analyses the latest international tax law developments in dispute resolution settlement protocols and the need for effective multilateral solutions to prevent international double taxation. While several treaties currently minimise the risks of international double taxation, more must be achieved to provide judicial remedies in cases where two states want to tax the same income simultaneously. The OECD has developed a dispute resolution system based on arbitration clauses to be introduced in conventions signed by the state and a brand-new MLI (multilateral instrument) that should be applicable on a broader scale. These remedies have proven unsatisfactory as the taxpayer is not entitled to play any role in these (arbitration) procedures and cannot stand personally in front of any panel. The authors argue that such a scenario is inconsistent with the rule of law and the due process clauses and should be amended. Creating a supranational court with the entitlement to adjudicate the power to tax would be the optimal solution, but this would collide with the position of several states and their distrust of the international judiciary in tax matters. Full article

This paper investigates the influence of the volute geometry on the hydraulic performance of a low-specific-speed centrifugal pump using numerical simulations. The performance characteristics for the pump with the volute geometry designed using the constant velocity method show a significant discrepancy between the design point and the best efficiency point (BEP). This design methodology also results in a relatively flat head–capacity curve. These are both undesirable characteristics which can be mitigated by a reduction in the volute throat area. This design methodology also leads to a reduction in the power consumption and an increase in efficiency, especially at underload and design flow conditions. These impacts of the volute throat area on performance characteristics are investigated in terms of the change in internal flow characteristics due to the reduction in the volute throat area. Another aspect of the study is the impact of the width of the volute gap on performance characteristics. A reduction in the gap width results in a nearly vertical shift of the head–capacity curve, so that head delivered is higher across all the flow rates as the gap width is reduced. This is also accompanied by a slight improvement in efficiency under design flow and overload conditions. Numerical simulations are used to relate the change in performance characteristics with internal flow characteristics. Full article

A prerequisite for decreasing the intensification of energy in buildings is to evaluate and understand the influencing factors of building energy performance (BEP). These factors include building envelope features and outdoor climactic conditions, among others. Based on the importance of the influencing factors in the development of the building energy prediction model, various researchers are continuously employing different types of factors based on their popularity in academic literature, without a proper investigation of the most relevant factors, which, in some cases, potentially leads to poor model performance. However, this can be due to the absence of an adequate comprehensive analysis or review of all factors influencing BEP ubiquitously. Therefore, this paper conducts a holistic and comprehensive review of studies that have explored the various factors influencing energy use in residential and commercial buildings. In total, 74 research articles were systematically selected from the Scopus, ScienceDirect, and Institute of Electrical Electronics Engineers (IEEE) databases. Subsequently, by means of a systematic and bibliometric analysis, this paper comprehensively analyzed several important factors influencing BEP. The results reveals the important factors (such as windows and roofs) and engendered or shed light on the application of some energy-efficient strategies such as the utilization of a green roof and photovoltaic (PV) window, among others. Full article

Backward erosion piping, a soil erosion phenomenon induced by seepage, compromises the stability of water-retaining structures such as dikes. During floods, the seepage in the dike body increases due to high water levels, which directly affects the progression of the piping channel. The formation of the piping channel then impacts the stability of the dike. In this paper, an improved piping model that considers the impact of seepage in the dike body is proposed based on Wewer’s model. Specifically, we added a seepage field of the dike body to the original model to account for the impact of dike-body seepage on the evolution of piping. The seepage field of the dike body is solved using Darcy’s law and the continuity equation for unsaturated porous media. In addition, this approach also incorporates the coupling effect of seepage stress. The accuracy of the model was verified through comparing the calculated results with the IJkdijk experiment and Wewer’s results. The effects of BEP on dike stability were investigated using the proposed improved piping model. The two major conclusions of the study are that (1) the incorporation of unsaturated seepage enhanced the performance of the piping model, allowing it to more accurately simulate the development of pipe length and the changing of pore pressure; and (2) the formation of the pipe impacted dike stability, leading to a substantial reduction in the safety factor of the dike slope. Full article

Centrifugal pumps are essential in many industrial processes. An accurate operation diagnosis of centrifugal pumps is crucial to ensure their reliable operation and extend their useful life. In real industry applications, many centrifugal pumps lack flowmeters and accurate pressure sensors, and therefore, it is not possible to determine whether the pump is operating near its best efficiency point (BEP). This paper investigates the detection of off-design operation and cavitation for centrifugal pumps with accelerometers and current sensors. To this end, a centrifugal pump was tested under off-design conditions and various levels of cavitation. A three-axis accelerometer and three Hall-effect current sensors were used to collect vibration and stator current signals simultaneously under each state. Both kinds of signals were evaluated for their effectiveness in operation diagnosis. Signal processing methods, including wavelet threshold function, variational mode decomposition (VMD), Park vector modulus transformation, and a marginal spectrum were introduced for feature extraction. Seven families of machine learning-based classification algorithms were evaluated for their performance when used for off-design and cavitation identification. The obtained results, using both types of signals, prove the effectiveness of both approaches and the advantages of combining them in achieving the most reliable operation diagnosis results for centrifugal pumps. Full article

Ammonia (NH₃) is a critical chemical for fertilizer production and a potential future energy carrier within a sustainable hydrogen economy. The industrial Haber–Bosch process, though effective, operates under harsh conditions due to the high thermodynamic stability of the nitrogen molecule (N₂). This motivates the search for alternative catalysts that facilitate ammonia synthesis at milder temperatures and pressures. Theoretical and experimental studies suggest that circumventing the trade-off between N–N activation and subsequent NH_x hydrogenation, governed by the Brønsted–Evans–Polanyi (BEP) relationship, is key to achieving this goal. Recent studies indicate metal phosphides as promising catalyst materials. In this work, a comprehensive density functional theory (DFT) study comparing the mechanisms and potential reaction pathways for ammonia synthesis on Fe(110) and Fe₂P(001) is presented. The results reveal substantial differences in the adsorption strengths of NH_x intermediates, with Fe₂P(001) exhibiting weaker binding compared to Fe(110). For N–N bond cleavage, multiple competing pathways become viable on Fe₂P(001), including routes involving the pre-hydrogenation of adsorbed N₂ (e.g., through *NNH*). Analysis of DFT-derived turnover rates as a function of hydrogen pressure (H₂) highlights the increased importance of these hydrogenated intermediates on Fe₂P(001) compared to Fe(110) where direct N₂ dissociation dominates. These findings suggest that phosphorus incorporation modifies the ammonia synthesis mechanism, offering alternative pathways that may circumvent the limitations of traditional transition metal catalysts. This work provides theoretical insights for the rational design of Fe-based catalysts and motivates further exploration of phosphide-based materials for sustainable ammonia production. Full article

The growing adoption of Building Information Modeling (BIM) within the architectural, engineering, and construction (AEC) sector raises questions about the quality of BIM data deliverables for project owners. Therefore, assessment and evaluation of such BIM data against relevant documents such as the BIM Execution Plan (BEP), the Level of Definition (LOD)/Level of Information (LOI) matrix, and quality control customized checklists become critical, especially in large construction projects. This study primarily aims to create an automated system for assessing the quality of 3D BIM model data, utilizing a proposed project quality control checklist. The automated system consists of four key elements: a BIM-based model, a Data Extraction and Analysis Module, a Data Storage Module, and a Data Visualization Module. The Data Extraction and Analysis Module extracts relevant information and parameters from BIM models to evaluate their quality against predefined checklists. Then, it transfers the information and stores the results in a database. The database is connected to an engineering project collaboration tool, ProjectWise, to automatically update and store the data in the cloud. The database is then connected to an interactive data visualization platform, Power BI, to enable automatic visualization of the generated quality assessment results of the BIM models’ data. This system was applied to a Canadian infrastructure construction project by its BIM department during the preliminary and detailed design phases. It demonstrated an average quality score (AQS) of 87.6% for the BIM models and significantly reduced failing items by around 30%. This study concludes that the system offers a robust, practical solution for enhancing the quality control process in BIM model data management, thereby aiding engineers in timely model adjustments to meet project requirements. Full article

Uranium, a cornerstone for nuclear energy, facilitates a clean and efficient energy conversion. In the era of global clean energy initiatives, uranium resources have emerged as a vital component for achieving sustainability and clean power. To fulfill the escalating demand for clean energy, continual advancements in uranium mining technologies are imperative. Currently, established uranium mining methods encompass open-pit mining, underground mining, and in situ leaching (ISL). Notably, in situ leaching stands out due to its environmental friendliness, efficient extraction, and cost-effectiveness. Moreover, it unlocks the potential of extracting uranium from previously challenging low-grade sandstone-hosted deposits, presenting novel opportunities for uranium mining. This comprehensive review systematically classifies and analyzes various in situ leaching techniques, exploring their core principles, suitability, technological advancements, and practical implementations. Building on this foundation, it identifies the challenges faced by in situ leaching and proposes future improvement strategies. This study offers valuable insights into the sustainable advancement of in situ leaching technologies in uranium mining, propelling scientific research and practical applications in the field. Full article

Large discrepancies can occur between building energy performance simulation (BEPS) outputs and reference data. Uncertainty and sensitivity analyses are performed to discover the significant contributions of each input parameter to these discrepancies. Variance-based sensitivity analyses typically require many stochastic simulations, which is computationally demanding (especially in the case of the large number of input parameters involved in the analysis). To overcome these impediments, this study proposes a reliable meta-model-based sensitivity analysis, including validation, Morris’ method, multivariate adaptive regression splines (MARS) meta-modeling, and Sobol’ method, to identify the most influential input parameters on BEPS prediction (annual energy consumption) at the early building design process. A hypothetical building is used to analyze the proposed methodology. Six statistical metrics are applied to verify and quantify the accuracy of the model. It is concluded that the cooling set-point temperature and g-value of the window are the most influential input parameters for the analyzed case study. Full article

In order to reduce the impact of production changes on the performances of pumps as turbines (PATs) in the process industry, it is imperative to lessen head variations at different mass flow rates. This study established a relationship equation between theoretical head and geometric parameters for multistage PATs. The influence of these parameters on the flatness of the head-flow (H-Q) curve was determined through derivation methods. The original PAT was a two-stage pump, and 12 PAT models were designed by modifying the geometric parameters of the positive guide vanes. Fluent software was employed for numerical simulations. The study found that numerical calculations aligned well with theoretical derivations for the flat H-Q curve. Considering the geometric variations in the positive guide vane, increasing the outlet placement angle, blade number, and throat area or decreasing the base circle diameter was able to flatten the H-Q curve effectively; at the best efficiency point, the throat area had the most significant impact on a slope, followed by the outlet placement angle, blade number, and base circle diameter, respectively. The individual contributions to reducing the slope were 0.53, 0.24, 0.1, and 0.09. In terms of the best efficiency point (BEP) of PATs, increasing the throat area appropriately was able to improve the BEP of the PAT by around 1.65% and shifted its BEP towards higher flow rates. However, in other cases, the BEPs all decreased. Increasing the outlet placement angle of the positive guide vane by 3° led to the BEP being reduced by 0.79%. When the number of positive guide vane blades was increased from 8 to 10, the BEP decreased by 1.24%. When the diameter of the base circle of the positive guide vane was decreased, the BEP of the turbine decreased by 0.06%. This study provides theoretical support and can serve as a reference for the design of multistage hydraulic turbines with flatter H-Q curves. Full article