Explore the vast range of titles available.

The rupture of the contact wire (CW) of a railway overhead contact line (OCL or catenary) is expected to be a rare event. However, when it occurs, and a pantograph transits under the already broken section of the CW, this can have catastrophic consequences for the pantograph which in turn can cause a further extension of the damaged portion on the OCL with a consequent disruption in the service and cause there to be a long time before the operating condition can be restored. Therefore, the prevention of such events through effective catenary monitoring is gaining significant attention. The purpose of this work is to investigate the feasibility of a monitoring system that can be installed at each end of an OCL section which is able to detect the occurrence of a broken CW event, sending an alert to the management traffic system, so as to stop the train traffic before the damaged catenary is reached by other trains. A nonlinear dynamic analysis is employed to model the OCL’s response following a simulated CW rupture and identify a set of variables that can be measured at the line’s extremities related to the occurrence of breakage in the CW. Several locations of the rupture of a CW section along the line are simulated to investigate the influence on the time pattern of the measured variables and consequently on the extraction of a signature. Finally, a proposed measurement setup is presented, combining accelerometers and displacement transducers, instead of the direct measurement of the axial load of the OCL conductors.

Optimizing chiller load (OCL) distribution in multi-chiller HVAC systems is critical for energy efficiency, yet existing algorithms often struggle with accuracy and convergence. This challenge is compounded by the fact that existing research predominantly focuses on chiller-centric optimization, often neglecting the significant energy consumption of auxiliary components. To address this gap, this study proposes a novel method utilizing Modelica/Simulink co-simulation to accurately model the entire refrigeration system, including chillers, pumps and cooling towers, thereby eliminating complex mathematical derivations and enhancing real-world applicability. To solve this holistic optimization problem, an Improved Particle Swarm Optimization (IPSO) algorithm is developed, which integrates a Phased Adaptive Decreasing Inertia Weight (PADIW) strategy, adaptive learning factors, and a mutation operator to enhance its global search capability and robustness. A case study of a shopping mall demonstrates the approach’s efficacy: over a six-month period, the optimization method reduces total refrigeration system consumption by 25.5% compared to the strategy of distributing the load equally and 15.5% compared to the human experience strategy. Notably, this case revealed that the water pumps, while accounting for less than 20% of total consumption, held a disproportionately large energy-saving potential of over 25%. Comparative experiments and Monte Carlo simulations further confirm the proposed IPSO’s superior convergence and robustness over standard PSO and other common metaheuristics. This study demonstrates that the synergy of Modelica/Simulink co-simulation and the IPSO algorithm is crucial for realizing the full energy-saving potential of the entire system, particularly from previously overlooked components like the water pumps.

A new [Cu4OCl6L4] cluster [L = 1-(allyl)-1H-imidazole] has been isolated and its crystal structure and spectroscopic properties determined. The compound crystallizes as a yellow solid in the monoclinic system, space group P21, with cell constants a = 10.6937(7) Å, b = 13.1004(7) Å, c = 13.2452(9) Å, β = 93.537(6)°, and two formula units per cell. The title tetranuclear complex has a central µ4-oxide ion surrounded tetrahedrally by four CuII atoms. Each Cu atom is connected to three others via bridging Cl atoms. The fifth coordination position, located on the central Cu─O axis on the outside of the cluster, is occupied by an N atom of the monodentate imidazole ligand. The resulting coordination geometry of the metal ion is a slightly distorted trigonal bipyramid with the O and N atoms in the axial positions. The molecular structure and spectroscopic data were obtained using density functional theory (DFT/HSEH1PBE) method with the cc-pVDZ basis set for C, H, N, O and Cl atoms, and the LANL2DZ basis set for the Cu atoms, and compared with the experimental data. Consequently, the experimental data well coherences with the theoretical ones.

This scientific paper aims to increase the voltage source converter (VSC) control efficiency in a multi-terminal high voltage direct current (MTDC) network during dynamic operations. In the proposed study, the Mayfly algorithm (MA) is used to modify the control parameters of VSC stations. Traditional strategies that modify VSC control settings using approximate linear models fail to produce optimal results because VSCs are nonlinear characteristics of the MTDC system. Particle swarm optimization (PSO) may produce optimal outcomes, but it is prone to becoming stuck in a local optimum. To modify the proportional-integral (P.I.) control parameters of the VSC station, the Mayfly algorithm, a modified form of PSO, is used. The suggested algorithm’s objective function simultaneously optimizes both the outer and inner control layers. A four-terminal MTDC test system is developed in PSCAD/EMTDC to assess the benefits of the proposed algorithm. For VSCs, a comparison of classical, PSO, and proposed MA-based tuned parameters is carried out. The integral of time multiplied by absolute error (ITAE) criterion is used to compare the performance of classical, PSO, and a proposed algorithm for VSC controller parameters/gains. With an ITAE value of 6.8521 × 10−6, the MA-based proposed algorithm computes the optimal values and outperforms its predecessor to adjust the VSCs controller gains. For (i) wind farm power variation, (ii) AC grid load demand variation, and (iii) ultimate permanent VSC disconnection, steady-state and dynamic performances are evaluated. According to the results, the proposed algorithm based MTDC system performs well during transients.

The correct representation of the relevant properties of a system is an essential requirement for the effective use and wide adoption of model-based practices in industry. Uncertainty is one of the inherent properties of any measurement or estimation that is obtained in any physical setting; as such, it must be considered when modeling software systems deal with real data. Although a few modeling languages enable the representation of measurement uncertainty, these aspects are not normally incorporated into their type systems. Therefore, operating with uncertain values and propagating their uncertainty become cumbersome processes, which hinder their realization in real environments. This paper proposes an extension of OCL/UML primitive datatypes that enables the representation of the uncertainty that comes from physical measurements or user estimates into the models, together with an algebra of operations that are defined for the values of these types.

Purpose Osteochondral lesions (OCLs) of the talus are a challenging and increasingly recognized problem in chronic ankle pain. Many novel techniques exist to try and treat this challenging entity. Difficulties associated with treating OCLs include lesion location, size, chronicity, and problems associated with potential graft harvest sites. Matrix-associated stem cell transplantation (MAST) is one such treatment described for larger lesions > 15 mm 2 or failed alternative therapies. This cohort study describes a 3 year review of the outcomes of talar lesions treated with MAST. Methods A review of all patients treated with MAST by a single surgeon was conducted. Pre-operative radiographs, MRIs, and FAOS outcome questionnaire scores were reviewed. Intraoperative classification was undertaken to correlate with imaging. Post-operative outcomes included FAOS scores, return to sport, revision surgery/failure of treatment, and progression to ankle fusion. Results In this study, 38 OCLs in 32 patients were identified. Median patient age was 35 years of which (68.8%) were male. Median length of follow-up was 36.7 months (range 12–64 months). (83%) returned to playing sport. Twenty-three patients underwent MAST in the setting of a failed previous operative attempt, with just nine having MAST as a first option. Nine patients out of 32 had a further procedure. Improvements were seen in all domains of the FAOS ( p  < 0.05). Conclusion MAST has demonstrated encouraging results in lesions which prove challenging to treat, even in a “failed microfracture” cohort. Level of evidence IV.

The conventional TEMPO/NaBr/NaOCl system for oxidation of cellulose to prepare nanocellulose materials has some shortcomings in terms of controlling side reactions and clogging in washing/filtration process. A new TEMPO/CaBr2/Ca(OCl)2 system was then developed to oxidize a hardwood bleached kraft pulp (HBKP) in water at pH 10 (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxyl radical). An aqueous Ca(OH)2 solution was used to continuously control the reaction mixture at pH 10. After oxidation, the reaction mixture containing the oxidized products and chemicals was directly filtered on a 40-μm-mesh nylon filter and the water-insoluble oxidized products on the filter were washed with water without any clogging. The carboxy content increased to 1.5 mmol/g and the mass recovery ratio decreased to 87.7% as the amount of Ca(OCl)2 was increased to 10.0 mmol/g-HBKP. The oxidized products contained calcium ions but almost no chloride ions, indicating that they comprised almost pure –(COO)2Ca groups. The ready filtration and washing of the oxidized products was probably owing to the low degree of dissociation of the –(COO)2Ca groups in water. The X-ray powder diffraction (XRD) and solid-state carbon 13 nuclear magnetic resonance (13C-NMR) analyses revealed that the crystallinities and crystal widths of the original cellulose I structure were mostly retained in the oxidized products. However, size-exclusion chromatography and viscosity analyses revealed that substantial depolymerization occurred on the cellulose and oxidized cellulose molecules in the products, as in TEMPO/NaBr/NaOCl-oxidized products.

Li6PS5Cl is a highly wanted sulfide-solid-electrolyte (SSE) for developing all-solid-state lithium batteries, due to its high ionic conductivity, good processability and abundant compositional elements. However, its cyclability is poor because of harmful side reactions at the Li6PS5Cl/Li interface and growth of lithium dendrites inside Li6PS5Cl phase. Herein, we report a simple interface-engineering remedy to boost the electrochemical performance of Li6PS5Cl, by coating its surface with a Li-compatible electrolyte Li3OCl having low electronic conductivity. The obtained Li6PS5Cl@Li3OCl core@shell structure exhibits a synergistic effect. Consequently, compared with the bare Li6PS5Cl, this composite electrolyte exhibits great performance improvements: 1) In Li|electrolyte|Li symmetric cells, the critical current density at 30 °C gets increased from 0.6 mA cm−2 to 1.6 mA cm−2, and the lifetime gets prolonged from 320 h to 1400 h at the cycling current of 0.2 mA cm−2 or from 10 h to 900 h at the cycling current of 0.5 mA cm−2; 2) In Li|electrolyte|NCM721 full cells running at 30 °C, the cycling capacity at 0.2 C (or 0.5 C) gets enhanced by 20% (or from unfeasible to be feasible) for 100 cycles and the rate capability reaches up to 2 C from 0.2 C; and in full cells running at 60 °C, the cycling capacity is increased by 7% at 0.2 C and the rate capability is enhanced to 3.0 C from 0.5 C. The experimental studies and theoretical computations show that the performance enhancements are due to the confined electron penetration and suppressed lithium dendrites growth at the Li6PS5Cl@Li3OCl interface. Herein, a simple interface-engineering remedy to boost the electrochemical performance of Li6PS5Cl is reported, by coating its surface with a Li-compatible electrolyte Li3OCl having low electronic conductivity. Due to a synergistic effect, the obtained Li6PS5Cl@Li3OCl core@shell structure exhibits great performance improvements compared with the bare Li6PS5Cl. [Display omitted] •A synergistic effect on enhancing battery performance is achieved by coating Li6PS5Cl with a shell of Li3OCl.•The Li6PS5Cl@Li3OCl core@shell structure is produced by just manually grinding their powders for a few minutes.•In Li.|electrolyte|Li symmetric cells, the critical current density at 30 °C gets increased by 2.6 times•In Li|electrolyte|NCM721 full cells, the rate capability gets enhanced by 10 times running at 30 °C and by 6 times at 60 °C.•The performance enhancement is due to the confined electron penetration and suppressed lithium dendrites growth at the electrolytes interface.

Testing model transformations poses several challenges, one of which is how to automatically generate effective test suites. Existing approaches in the literature often focus on exploiting either structural aspects of models captured by a metamodel or restrictions as contracts within the specification of model transformation for a partition analysis to generate test suites. However, test cases for model transformation, i.e., test models, often need to be defined not only from one restriction source as within the current methods but also from many different sources. This paper introduces a method to facilitate defining test models on such multiple restriction domains. This method also allows the tester to flexibly select and combine constraints as a restriction on test models for different strategies and objectives of the model transformation testing. We develop a support tool based on the OCL tool USE and perform experiments on several different transformations to point out the effectiveness of our method.

Goal-oriented modeling languages have been proposed to elicit, analyze, and document high-level system requirements in the early stages of the requirements engineering (RE) process. Problems during this stage may disseminate to the subsequent stages in the software development process and artifacts. Therefore, improving the quality of goal models would improve the quality of the requirements and, consequently, the quality of the developed system. This paper proposes an approach to help modelers identify quality improvement opportunities in Goal-oriented Requirements Language (GRL) goal models. To this end, a list of GRL bad smells (i.e., bad quality symptoms) is introduced and evaluated by experts. Then, an automated rule-based technique is proposed to detect the instances of these smells. The proposed approach is evaluated using a dataset gathered from academic and real-world projects. The results show that the developed technique could successfully detect the instances of the proposed bad smells in the evaluation models. We also found that the instances of the proposed bad smells were prevalent in both academic and industrial settings. The proposed bad smells and the detection technique provide a tool to locate quality improvement opportunities in GRL goal models.