Search Results (208)

This study focuses on the optimization of valve assemblies in downhole rod pumping units (DRPUs), which remain the predominant artificial lift technology in oil production worldwide. The research addresses the critical issue of premature failures in DRPUs caused by leakage in valve pairs, i.e., a problem that accounts for approximately 15% of all failures, as identified in a statistical analysis of the 2022 operational data from the Uzen oilfield in Kazakhstan. The leakage is primarily attributed to the accumulation of mechanical impurities and paraffin deposits between the valve ball and seat, leading to concentrated surface wear and compromised sealing. To mitigate this issue, a novel valve assembly design was developed featuring a flow turbulizer positioned beneath the valve seat. The turbulizer generates controlled vortex motion in the fluid flow, which increases the rotational frequency of the valve ball during operation. This motion promotes more uniform wear across the contact surfaces and reduces the risk of localized degradation. The turbulizers were manufactured using additive FDM technology, and several design variants were tested in a full-scale laboratory setup simulating downhole conditions. Experimental results revealed that the most effective configuration was a spiral plate turbulizer with a 7.5 mm width, installed without axis deviation from the vertical, which achieved the highest ball rotation frequency and enhanced lapping effect between the ball and the seat. Subsequent field trials using valves with duralumin-based turbulizers demonstrated increased operational lifespans compared to standard valves, confirming the viability of the proposed solution. However, cases of abrasive wear were observed under conditions of high mechanical impurity concentration, indicating the need for more durable materials. To address this, the study recommends transitioning to 316 L stainless steel for turbulizer fabrication due to its superior tensile strength, corrosion resistance, and wear resistance. Implementing this design improvement can significantly reduce maintenance intervals, improve pump reliability, and lower operating costs in mature oilfields with high water cut and solid content. The findings of this research contribute to the broader efforts in petroleum engineering to enhance the longevity and performance of artificial lift systems through targeted mechanical design improvements and material innovation. Full article

Based on the engineering background of a new type of segmental-assembled steel temporary beam buttress, the fatigue strength evaluation method of the steel box girders with open longitudinal ribs was taken as the research objective. The fatigue stress calculation analysis and the full-scale fatigue loading test for the steel box girder local component were carried out. The accuracy of the finite-element model was verified by comparing it with the test results, and the rationality of the fatigue strength evaluation methods for welded joints was deeply explored. The results indicate that the maximum nominal stress occurs at the weld toe between the transverse diaphragm and the top plate at the edge of the loading area, which is the fatigue-vulnerable location for the steel box girder local components. The initial static-load stresses at each measuring point were in good agreement with the finite-element calculation results. However, the static-load stress at the measuring point in the fatigue-vulnerable position shows a certain decrease with the increase in the number of cyclic loads, while the stress at other measuring points remains basically unchanged. According to the finite-element model, the fatigue strengths obtained by the nominal stress method and the hot-spot stress method are 72.1 MPa and 93.8 MPa, respectively. It is reasonable to use the nominal stress S-N curve with a fatigue life of 2 million cycles at 70 MPa and the hot-spot stress S-N curve with a fatigue life of 2 million cycles at 90 MPa (FAT90) to evaluate the fatigue of the welded joints in steel box girders with open longitudinal ribs. According to the equivalent structural stress method, the fatigue strength corresponding to 2 million cycles is 94.1 MPa, which is slightly lower than the result corresponding to the main S-N curve but within the range of the standard deviation curve. The research results of this article can provide important guidance for the anti-fatigue design of welded joints in steel box girders with open longitudinal ribs. Full article

We propose Observer-Linked Branching (OLB), a mathematically rigorous extension of quantum theory in which an observer’s cognitive commitment actively modulates collapse dynamics at macroscopic scales. The OLB framework rests on four axioms, employing a norm-preserving nonlinear Schrödinger evolution and Lüders-type projection triggered by crossing a cognitive commitment threshold. Our expanded formalism provides five main contributions: (1) deriving Lie symmetries of the observer–environment interaction Hamiltonian; (2) embedding OLB into the Consistent Histories and path-integral formalisms; (3) multi-agent network simulations demonstrating intentional synchronisation toward shared macroscopic outcomes; (4) detailed statistical power analyses predicting measurable biases (up to ~5%) in practical experiments involving traffic delays, quantum random number generators, and financial market sentiment; and (5) examining the conceptual, ethical, and neuromorphic implications of intent-driven reality selection. Full reproducibility is ensured via the provided code notebooks and raw data tables in the appendices. While the theoretical predictions are precisely formulated, empirical validation is ongoing, and no definitive field results are claimed at this stage. OLB thus offers a rigorous, norm-preserving and falsifiable framework to empirically test whether cognitive engagement modulates macroscopic quantum outcomes in ways consistent with—but extending—standard quantum predictions. Full article

Type IV composite overwrapped pressure vessels (COPVs) store hydrogen at pressures up to 70 MPa and must meet stringent safety standards through physical testing. However, full-scale burst, plug torque, axial compression, impact, and drop tests are time-consuming and costly. This study proposes a unified finite element analysis (FEA) workflow that replicates these mandatory tests and predicts failure behavior without physical prototypes. Axisymmetric and three-dimensional solid models with reduced-integration elements were constructed for the polyamide liner, aluminum boss, and carbon/epoxy composite. Burst simulations showed that increasing the hoop-to-axial stiffness ratio shifts peak stress to the cylindrical region, promoting a longitudinal rupture—considered structurally safer. Plug torque and axial load simulations revealed critical stresses at the boss–composite interface, which can be reduced through neck boss shaping and layup optimization. A localized impact with a 25 mm sphere generated significantly higher stress than a larger 180 mm impactor under equal energy. Drop tests confirmed that 45° oblique drops cause the most severe dome stresses due to thin walls and the lack of hoop support. The proposed workflow enables early-stage structural validation, supports cost-effective design optimization, and accelerates the development of safe hydrogen storage systems for automotive and aerospace applications. Full article

This paper proposes a steel-ECC ordinary concrete composite continuous bridge deck structure to address the cracking problem of simply supported beam bridge deck continuity. Through theoretical and experimental research, a high-performance ECC material was developed. The ECC material has a compressive strength of 57.58 MPa, a tensile strain capacity of 4.44%, and significantly enhanced bending deformation ability. Bonding tests showed that the bond strength of the ECC-reinforcing bar interface reaches 22.84 MPa when the anchorage length is 5d, and the splitting strength of the ECC-concrete interface is 3.58 MPa after 4–5 mm chipping treatment, with clear water moistening being the optimal interface treatment method. Full-scale tests indicated that under 1.5 times the design load, the crack width of the ECC bridge deck continuity structure is ≤0.12 mm, the maximum deflection is only 5.345 mm, and the interface slip is reduced by 42%, achieving a unified control of multiple cracks and coordinated deformation. The research results provide a new material system and interface design standards for seamless bridge design. Full article

To meet the EU’s ambitious recycling targets, it is crucial to expand mechanical recycling to include currently underutilized waste streams, such as mixed commercial waste (MCW), which today achieves a recycling rate of only 3–5%. This study addresses the challenge of recovering polypropylene (PP) from MCW and demonstrates a viable process to do so. The goal was to develop and test industrial-scale process concepts to extract PP and transform it into high-quality recyclate. Two process concepts were developed and tested at industrial scale to extract PP as a pre-concentrate. The recovered material was further sorted, shredded, washed, and granulated, ultimately reaching End-of-Waste status. Material analysis confirmed that the resulting PP granulate meets all relevant quality standards. A total of 456.8 kg of this recyclate was processed into market-ready products. To the best of the authors’ knowledge, this is the first demonstration of plastic products made entirely from MCW. By covering the full value chain—from waste to final product—this study highlights a viable and scalable approach for integrating complex waste streams into high-quality material cycles, thereby contributing to circular economy strategies. Full article

The patch loading resistance of slender steel plate girders is a critical factor in the design of launched steel and composite steel–concrete bridges. Traditional design methods enhance patch loading resistance through various stiffening techniques, with contributions typically estimated via code expressions calibrated on experimental data that do not always reflect the complexities of full-scale bridge applications. Finite Element (FE) modeling offers a more realistic alternative, though its practical application is often hindered by modeling uncertainties and nonlinearities. To bridge this gap, this paper introduces an advanced FE modeling approach. It provides a comprehensive description of an FE model that accurately predicts both the load–displacement behavior and the patch loading resistance. The model is benchmarked against a broad set of experimental tests and systematically investigates the effects of key modeling parameters and their interactions—material stress–strain law, boundary condition representation, stiffness of the load introduction area, initial geometric imperfections, and solving algorithms. Key findings demonstrate that a bilinear elastoplastic material model with hardening is sufficient for estimating ultimate resistance, and kinematic constraints can effectively replace rigid transverse stiffeners. The stiffness of the load application zone significantly influences the response, especially in launched bridge scenarios. Initial imperfections notably affect both stiffness and strength, with standard fabrication tolerances offering suitable input values. The modified Riks algorithm is recommended for its efficiency and stability in nonlinear regimens. The proposed methodology advances the state of practice by providing a simple yet reliable FE modeling approach for predicting patch loading resistance in real-world bridge applications, leading to safer and more reliable structural designs. Full article

This paper presents a novel small-scale system for drinking water treatment from surface waters, designed to rely on gravity as the only source of energy driving the treatment process. The pilot-scale setup, designed for a flow rate of 0.5 L/s, was tested at the Cornell University Water Filtration Plant (CWFP) for a total period of 5 months of operation. The experiments evaluated the influence of selected process parameters on system performance. The identified best operation practices were used to complete a comparative study against CWFP’s full-scale treatment process and to conduct a performance assessment in the context of various legislative landscapes. The objective of the work was to determine both the advantages and disadvantages of the proposed technology over established solutions. Over the study period, the average turbidity of the produced water was equal to 0.54 NTU. The pilot complied with the United States Environmental Protection Agency (US EPA) turbidity standard of <0.3 NTU 47.1% of the time and <1 NTU for 89.9% of the time, thus falling short of the standard of <0.3 NTU 95% of the time and <1 NTU 100% of the time. For 99.5% of the time, it complied with the World Health Organization turbidity guideline of <5 NTU for chlorination treatment. The benchmark conventional system outperformed the tested prototype, complying with the US EPA standards for the entire duration of the study. The tested process also generated a waste stream, which accounted on average for more than 10% of the total raw water volume. Full article

Background/Objectives: The use of standardized assessment tools within the nursing care process is a globally established practice, widely recognized as a foundation for evidence-based evaluation. Accurate translation is essential to ensure their correct and consistent clinical use. While effective, traditional procedures are time-consuming and resource-intensive, leading to increasing interest in whether artificial intelligence can assist or streamline this process for nursing researchers. Therefore, this study aimed to assess the translation’s quality of nursing assessment scales performed by ChatGPT 4.0. Methods: A total of 31 nursing rating scales with 772 items were translated from English to Italian using two different prompts, and then underwent a deep lexicometric analysis. To assess the semantic accuracy of the translations the Sentence-BERT, Jaccard similarity, TF-IDF cosine similarity, and Overlap ratio were used. Sensitivity, specificity, AUC, and AUROC were calculated to assess the quality of the translation classification. Paired-sample t-tests were conducted to compare the similarity scores. Results: The Maastricht prompt produced translations that are marginally but consistently more semantically and lexically faithful to the original. While all differences were found to be statistically significant, the corresponding effect sizes indicate that the advantage of the Maastricht prompt is slight but consistent across all measures. The sensitivity of the prompts was 0.929 (92.9%) for York and 0.932 (93.2%) for Maastricht. Specificity and precision remained for both at 1.000. Conclusions: Findings highlight the potential of prompt engineering as a low-cost, effective method to enhance translation outcomes. Nonetheless, as translation represents only a preliminary step in the full validation process, further studies should investigate the integration of AI-assisted translation within the broader framework of instrument adaptation and validation. Full article

The construction sector faces growing pressure to adopt sustainable alternatives amid the global plastic-waste crisis. This study presents a novel use of mechanically recycled high-density polyethylene (HDPE) and polypropylene (PP) to manufacture full-scale plastic rebars for mortar-free, light-load construction applications. A total of 48 samples, plain and ribbed, across three diameters (12 mm, 19 mm, and 25 mm) were fabricated and tested. Due to the absence of standardized protocols for recycled plastic rebars, tensile testing was conducted in reference to ASTM A615. Characterization techniques such as X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM) confirmed the material’s structural features and polymer integrity. XRD confirmed the crystalline phases of HDPE and PP, while SEM revealed ductile fracture in HDPE and brittle failure in PP. The 25 mm ribbed PP rebars demonstrated superior performance, achieving a maximum load capacity of 12.2 ± 0.6 kN, a toughness index of 19.3 ± 1.0, and energy absorption of 101.6 ± 5.0 N-m × 10. These results affirm their suitability for lightweight structural components such as boundary walls, partition panels, and mortar-free interlocking systems. Unlike prior studies that confined recycled plastics to filler roles in composites, this work validates their direct application as full-section, load-bearing members. Additionally, a polynomial-based empirical model was formulated to predict the tensile behavior of the recycled rebars. The findings underscore the potential of mechanical extrusion as a low-emission, scalable solution to convert plastic waste into durable construction materials that support circular economic principles. Full article

As a key roadside safety feature, longitudinal guardrail steel barriers are purposefully designed to contain and redirect errant vehicles to prevent roadway departure, dissipate impact energy through plastic deformation, and reduce the severity of vehicle crashes. Nevertheless, these systems should be carefully designed and assessed, as localized rupturing, especially near splice or impact locations, can lead to catastrophic failures, compromising vehicle containment, violating crash safety standards, and ultimately jeopardizing the safety of occupants and other road users. Before conducting full-scale crash testing, finite element analysis (FEA) tools are widely employed to evaluate the design efficiency, optimize system configurations, and preemptively identify potential failure modes prior to expensive physical crash testing. To accurately assess system behavior, calibrated material models and precise failure criteria must be utilized in these simulations. Despite the existence of numerous failure criteria and material models, the material characteristics of AASHTO M-180 guardrail steel have not been fully investigated. This paper significantly advances the FE modeling of ductile fracture in guardrail steel, addressing a critical need within the roadside safety community. This study formulates stress-state-dependent failure criteria and proposes advanced material modeling techniques. Extensive experimental testing was conducted on steel specimens having various triaxiality and Lode parameter values to reproduce a wide spectrum of complex, three-dimensional stress-state loading conditions. The test results were then used to identify material properties and construct a failure surface. Subsequent FEA, which incorporated the Generalized Incremental Stress-State-Dependent Damage Model (GISSMO) in conjunction with two LS-DYNA material models, illustrates the capability of the developed surface and material input parameters to predict material behavior under various stress states accurately. A parametric study was completed to further validate the proposed models, highlighting their robustness and reliability. Full article

Ribbed slabs are a solution for increasing the bending capacity while reducing the total concrete consumption and the dead weight compared to conventional reinforced concrete slabs. The EN 1992-1.2 standard contains a tabulated method (TM) for the fire design of these structures, which suggests combinations of cross-sectional dimensions and concrete cover thickness to determine the fire resistance. Using a finite element (FE) model solved with Abaqus software, a transient thermal analysis of these slabs was performed, correlating the results with the standardized TM. Cross-sections with different concrete widths and concrete covers were numerically tested to define a new TM based on the same criteria proposed by the EN. To validate the FE models, the results were compared with the experimental data of two full-scale specimens of ribbed slabs. It was found that the current TM is not consistent in all cases, and the concrete cover needs to be improved by between 20 and 50%. A fire design of ribbed slabs based on EN 1992-1.2 shows that the reinforcement is heated beyond its critical temperature, but the flange thickness can be reduced. A new tabular procedure is proposed based on the critical temperature of the reinforcement, the concrete cross-section, and the thermal insulation criteria. Full article

Neonates with congenital heart disease (CHD) are at increased risk of growth failure and necrotizing enterocolitis (NEC), making nutritional management crucial for their outcomes. This study aimed to evaluate the impact of a standardized feeding protocol on growth and NEC incidence in CHD infants. A retrospective study was conducted at a tertiary care center, including neonates diagnosed with CHDs from January 2020 to March 2023. Patients were divided into two groups: those receiving the standardized feeding protocol (protocol group, n = 12) and those who did not (non-protocol group, n = 39). Key metrics such as growth velocity at discharge, anthropometric z score changes at discharge since birth, days to full enteral feeds, NEC incidence, and length of stay were analyzed. Statistical comparisons were made using two-tailed Mann-Whitney test and chi-squared tests. The NEC incidence was 10% in the non-protocol group and 0% in the protocol group (p = 0.25), with no significant difference. All anthropometric growth markers at the time of discharge differed between the groups, with the protocol group demonstrating favorable outcomes across all measured variables; however, these differences did not reach statistical significance. The time to reach full enteral feeds was shorter (8.5 days vs. 11 days; p = 0.22), and length of stay was shorter in the protocol group (17 days vs. 23 days; p = 0.14), although neither was statistically significant. Although the protocol group showed trends towards reduced NEC and improved growth, this was not statistically significant, which could have been because of the small sample size. Our findings suggest that a standardized feeding protocol may reduce the time to full enteral feeds and hospital stay, but further large-scale studies are needed to confirm these results. Full article

“Suero costeño”, a type of sour cream, is a traditional dairy product made mainly in the Colombian Caribbean region. In this study, we aim to characterize the physicochemical, microbiological, and rheological properties of suero costeño produced in Córdoba, Colombia. Samples of suero costeño were obtained from local producers, and physicochemical, microbiological, and rheologically (stationary tests) analyses were performed. A suero costeño was developed at a pilot scale and compared with that produced artisanally. The results showed great variability in the physicochemical characteristics of the suero costeño made by the different artisanal producers, with it being classified as either a full-fat sour cream or light sour cream, with values of protein (2–9%) and pH (3.5–5.8) similar to traditional dairy products from other countries. The Suero costeño samples showed an absence of Salmonella spp. and high counts of molds and yeasts, coliforms, Escherichia coli, and coagulase-positive Staphylococcus aureus, which is associated with the quality of the raw milk used and poor hygiene practices in the manufacturing process. Suero costeño can be classified as a pseudoplastic fluid, with some presenting thixotropy (19–93%), which may cause changes in the internal structure. Due to the great variability in its physicochemical, microbiological, and rheological characteristics, it is necessary to standardize the production process by applying good manufacturing practices to improve the marketing of this Colombian culinary product. Full article

Background and Objectives: Virtual reality (VR)-based interventions provide immersive and interactive environments that can enhance motor learning and deliver real-time feedback, offering potential advantages over conventional therapies. This systematic review evaluated the impact of non-immersive and immersive VR exergaming interventions versus conventional therapy on balance in Parkinson’s disease (PD) through a detailed analysis of randomized controlled trials (RCTs). Materials and Methods: A comprehensive search was conducted across the PubMed, Lilacs, IBECS, CENTRAL, Web of Science (WOS), EBSCOHost, and SciELO databases. Article selection and duplicate removal were managed using Rayyan QCRI. The quality of the evidence was assessed using the GRADE system. Results: From an initial screening of 100 studies, 58 underwent title and abstract screening. After full-text evaluation, 11 RCTs met the inclusion criteria, involving 518 participants with PD (average age: 67.3 years; 67.95% men). The balance outcomes were primarily measured using the Berg balance scale (BBS), employed in most studies (n = 9). The pooled analysis demonstrated a significant improvement in the balance scores for the experimental groups compared to the controls, with a standardized mean difference (SMD) of 0.58 [95% CI: 0.07, 1.09, p = 0.03]. However, the heterogeneity was substantial (I² = 77%). The analysis of the six-minute walking test (6 MWT), as another outcome of four articles, revealed a mean difference of 32.99 m [95% CI: −8.02, 74.00], but the effect was not statistically significant (p = 0.11). The heterogeneity for this outcome was moderate (I² = 41%), indicating some variability across studies. Alternative tools, such as the Tinetti Performance-Oriented Mobility Assessment (POMA) scale, the UPDRS III, and the sensory organization test (SOT), were also evaluated where possible. Conclusions: VR-based interventions offer promise for improving balance in Parkinson’s disease, enhancing rehabilitation engagement. Their integration into clinical practice could complement conventional therapy. However, further research is needed to optimize protocols, standardize parameters, and maximize their impact on mobility, independence, and quality of life. Full article