Search Results (1,732)

This study examines the impacts of key abrasive water jet machining (AWJM) parameters on the machinability of AA7175–15 wt.% ZrB₂ metal matrix composites produced via a two-step stir casting route. Jet pressure (100–300 MPa), traverse speed (70–130 mm/min), standoff distance (3–5 mm), and abrasive flow rate (250–450 g/min) were systematically varied to evaluate their effects on surface roughness (Ra), kerf taper angle (KA), and material removal rate (MRR). The experimental setup was designed using response surface methodology based on a central composite design (RSM–CCD), enabling both interaction and curvature effects to be assessed. Analysis of variance indicates that jet pressure exerts the strongest influence on MRR, which may be attributed to the increased kinetic energy and penetration capability of abrasive particles at higher pressures. In contrast, traverse speed was found to play a dominant role in controlling surface roughness and kerf geometry. As traverse speed increased, Ra and kerf taper angle tended to rise, likely due to reduced jet–material interaction time and incomplete erosion of the hard ZrB₂-reinforced matrix. Abrasive flow rate contributed positively to MRR up to higher levels, although its effect appeared secondary compared to jet pressure. Regression models developed for all machining responses showed strong predictive performance, with coefficients of determination exceeding 0.95 and statistically insignificant lack-of-fit, suggesting adequate representation of the underlying process behaviour within the investigated parameter range. Scanning electron microscopy of the machined surfaces revealed erosion features such as abrasive ploughing, particle pull-out, and striation formation. These surface morphologies are consistent with the observed variations in Ra and kerf characteristics and reflect the combined ductile–brittle erosion response of the composite. Overall, the study identifies optimised AWJM parameter combinations that can improve both surface quality and machining efficiency when processing AA7175–ZrB₂ composites. Full article

Surrogate-assisted optimization can reduce the number of repeated solid rocket motor (SRM) simulations, but a globally accurate surrogate is not necessarily reliable where design decisions are made: near active constraints. This study develops a low/medium-fidelity surrogate workflow for SRM performance prediction and constraint-robust screening. The low-fidelity response is obtained from a zero-dimensional internal-ballistics solver, and the medium-fidelity response is obtained from SrmStudio, an engineering-level SRM internal-ballistics design and simulation software. Residual correction and autoregressive Co-Kriging (AR1) models are assessed through global holdout accuracy, boundary-focused subsets, calibrated predictive intervals, same-budget enrichment comparisons, and SrmStudio consistency replay. Although the global coefficient of determination exceeds 0.99, the burn-time-boundary and pressure-exponent-sensitive subset MAPEs are approximately 28–47% higher than the final five-response global mean; the separation-boundary and high-pressure subsets do not exhibit the same increase. Calibrated 90% AR1 intervals achieve 90.8–96.7% coverage on the boundary test set and identify regions in which mean-only feasibility decisions are less reliable. A direct weight search further shows how sampling performance changes with the score composition after a boundary pool has been identified. Tolerance-boundary augmentation reduces the local thrust-window prediction error from 0.802 to 0.062 percentage points. Within the adopted simulation hierarchy, SrmStudio replay identifies a numerically promising candidate whose mean thrust increases from the SrmStudio baseline of 3866.67 N to 4000.67 N, a simulator-relative improvement of 3.47%, while satisfying the nominal constraints. Robustness analysis shows that the pressure exponent n is the limiting uncertainty, with an admissible calibration boundary of only ±0.191%. Full article

Switched reluctance motors (SRMs) are attractive for fault-tolerant drives because their rare-earth-free rotor and intrinsic phase isolation support continued operation after a converter fault. Realising this requires a post-fault control policy that preserves both torque tracking and per-phase thermal balance, with the latter being a safety-relevant design consideration motivated by—though not herein verified against—ISO 26262. This paper proposes and evaluates, by simulation, a three-layer fault-tolerant finite-control-set model predictive control (FCS-MPC) architecture for a four-phase 8/6 SRM under a single open-phase converter fault. The layers are (i) a vector-set reconfiguration from the eight healthy, active vectors to the twenty-six admissible post-fault vectors, which restores controllability of the reduced converter; (ii) soft commutation expressed as a position-dependent penalty inside the MPC cost; and (iii) asymmetry-aware balancing that evens out the accumulated thermal load across the three healthy phases. We additionally analyse an activated-on-demand max-penalty thermal limiter and show, both analytically and in simulation, that it shares its optimiser with the variance-based balancing term and therefore confers no measurable benefit over it; it is consequently retained only as an optional on-demand limiter rather than a separate layer. The architecture is benchmarked against a fault-blind baseline, a rule-based hard fault-tolerant reference (Hard-FT), and intermediate configurations through a deterministic ablation across three critical operating points, complemented by a robustness assessment under measurement noise and parameter mismatch. A six-criteria fault-tolerance scorecard is reported as a methodological observation on the transferability of healthy-mode SRM specifications to post-fault operation. Full article

The paper presents a simulation and experimental study of a three-phase 12/8 Switched Reluctance Motor (SRM) operating in motoring mode. The operation of the asymmetric bridge converter is analyzed, and the mathematical equations describing the phase-current change under various commutation states in soft-switching mode (modulation of the upper transistors) are derived. An analytical model is used to examine the energy exchange between the battery, the power switches, and the phase inductance. For the purposes of the study, a simulation model was developed in the MATLAB/Simulink R2025b environment, including models of the battery, the power converter, and the SRM. Simulation studies were conducted under various load conditions and phase current values, yielding time-domain waveforms of the phase currents and voltages, as well as the electromagnetic torque. Experimental waveforms of the phase current and voltage, measured under conditions corresponding to those in the simulation studies, are presented. A comparative analysis was performed between the simulation and experimental results, with tabular and graphical dependencies presented, and the relative error between them determined. The results obtained show good agreement between the simulation model and the actual system, which confirms the applicability of the developed approach for the analysis and optimization of SRM drives. Full article

Background/Objectives: The PRO-CTCAE Average Composite Score (ACS), calculated as the mean of PRO-CTCAE composite scores, summarizes overall symptom and side effect burden. This study evaluated the test–retest reliability, responsiveness to change, known-groups validity, and sensitivity to group differences in the ACS. Methods: Analyses used the original PRO-CTCAE validation dataset, including lung (n = 174), breast (n = 222), and head and neck (n = 139) cancer cohorts, and data from the COMET-2 randomized phase III trial comparing cabozantinib (n = 53) and mitoxantrone–prednisone (n = 54) in men with previously treated prostate cancer. Test–retest reliability was assessed using intraclass correlation coefficients (ICCs) from two-way mixed-effects models for agreement. Responsiveness was evaluated by relating ACS change scores (Visit 1 minus follow-up Visit 2) to patient-reported global ratings of change (GRC; worsened, unchanged, or improved) using standardized response means (SRMs) and Jonckheere–Terpstra trend tests. Known-groups validity was examined by comparing mean ACS values between ECOG performance status groups (0–1 vs. 2–4). Sensitivity to treatment group differences was assessed using model-based area-under-the-curve (AUC) comparisons of longitudinal ACS trajectories. Results: Test–retest reliability was acceptable, with ICCs among GRC-defined stable patients of 0.80 (95% CI: 0.70–0.87) in lung cancer, 0.84 (95% CI: 0.77–0.89) in breast cancer, and 0.77 (95% CI: 0.63–0.86) in head and neck cancer; ICCs based on assessments completed one day apart ranged from 0.88 to 0.90. The ACS demonstrated responsiveness, with SRMs of 0.30/0.15/−0.37 (lung), 0.29/0.14/−0.40 (breast), and −0.01/−0.20/−0.56 (head/neck) for improved/no-change/worsened groups, respectively, and significant monotonic trends across GRC categories (all p < 0.01). Known-groups validity was supported by conceptually expected differences in ACS values across distinct levels of self-reported patient-reported physical functioning and ECOG performance status categories. Mean ACS values were lower among patients with good versus limited physical functioning (0.71 vs. 1.23 in lung cancer, 0.52 vs. 1.19 in breast cancer, and 0.69 vs. 1.29 in head and neck cancer) and among patients with ECOG PS 0–1 versus 2–4 (0.93 vs. 1.31, 0.74 vs. 1.22, and 0.90 vs. 1.06, respectively). In COMET-2, higher symptom burden was detected in the cabozantinib arm compared with the mitoxantrone–prednisone arm (AUC difference = 1.5, 95% CI: 0.2–2.8, p = 0.02). Conclusions: The ACS demonstrated acceptable test–retest reliability, responsiveness, and known-groups validity across multiple cancer populations. These findings support its use as a complementary summary measure of overall symptomatic adverse event burden alongside individual symptom-level analyses. Full article

Knee osteoarthritis is a prevalent condition that affects pain, mobility, and quality of life. The TRAK^® platform incorporates both therapeutic interventions and outcome assessment tools, such as range of motion (ROM) assessment. The responsiveness of knee ROM measurements obtained through TRAK^® platform remains unclear. This study evaluated the responsiveness of TRAK^® in measuring knee ROM through a digital rehabilitation programme delivered through TRAK^® and examined its association with changes in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Thirty-six participants with knee osteoarthritis completed TRAK^® intervention. Knee ROM and WOMAC outcomes were assessed at baseline, 8 weeks, and 32 weeks. Responsiveness was evaluated using repeated-measures analyses, standardised response mean (SRM), Cohen’s d, and correlations between changes in ROM and WOMAC scores. Mean ROM increased from 120° at baseline to 128° at 32 weeks, although these changes were not statistically significant (p = 0.262). Responsiveness indices were small (SRM = 0.12–0.28; Cohen’s d = 0.12–0.28). A moderate inverse correlation was observed between changes in ROM and WOMAC pain at 8 weeks (ρ = −0.514, p = 0.010), whereas associations with other WOMAC domains were weak and non-significant. Knee ROM measured using TRAK^® showed limited responsiveness during the TRAK^® intervention. Full article

Deborah Rodriguez’s The Kabul Beauty School belongs to the body of Western humanitarian literature produced post-9/11 portraying the significant role of America in the reconstruction of Afghanistan. This study analyzes how the memoir embodies what is conceptualized as ‘autoethnographic orientalism’, a critical framework that identifies how the Western subject constructs knowledge of the Orient through personal narratives that prioritize self-discovery by using autoethnographic conventions of reflexivity, participant observation, personal disclosure and affective engagement. Integrating intersectional complicity into the framework reveals the reproduction of orientalist hierarchies while claiming feminist solidarity with Afghan women. The close reading and qualitative analysis of the memoir identifies five dimensions of representational politics—memoir as an orientalist form, the autoethnographic gaze, intersectional complicity, rescue narratives and agential empowerment, and narrative blind spots. The study demonstrates how Rodriguez’s observation and documentation of cultural practices reinforce colonial discourse of perceived differences and deficiencies rather than arriving at a deeper cultural understanding. The findings suggest that post-9/11 humanitarian memoirs need to employ a critical reading practice that will engage with both the empathetic dimensions of the text as well as the structural complicity embedded in them. Full article

We analyze the effect of microscopic heterogeneity on the Lorenz curve of macroscopic observables. The Lorenz curve of a response function, being a cumulative and bounded quantity; it is often a more stable function than the corresponding probability density. We show here that by doing an exponent spectrum analysis of the complementary Lorenz curve, it is possible to obtain a reflection of the underlying heterogeneity that causes the response function to depart from a power law behavior. We demonstrate this framework first by synthetic data and then by analyzing the avalanche statistics of a two dimensional, Random Field Ising Model (RFIM) at zero temperature. This method can lead to possible use in estimating the microscopic heterogeneity of a system from the analysis of an estimated Lorenz curve, particularly in socio-economic and physical contexts where the full probability distribution function is unavailable. Full article

At present, the organisational landscape, which aims to provide value through its product and service offerings, must have the necessary infrastructure to deliver at the expected service levels. This requires the appropriate adaptation of existing frameworks, methods, and models to their business models, thereby generating consistent deliverables across time and industries. This is also applicable to Romanian Information Technology (IT) organisations, which face increasing pressure to deliver within the expected quality, time, and budget parameters. This study aims to assess the quality of stakeholder relationship management (SRM) as a higher-order organisational capability in Romanian IT organisations through a stakeholder-oriented subset of the Malcolm Baldrige National Quality Award (MBNQA) excellence framework and to explore its contribution to organisational quality, business continuity, and organisational resilience. A pilot study was conducted, using a sample of 52 Romanian IT professionals, to examine the applicability of four stakeholder-oriented MBNQA dimensions—Leadership and Governance, Workforce, Customers and Markets, and Community Engagement—as components of SRM quality. The findings provide preliminary evidence that these dimensions represent relevant elements for assessing SRM quality within the Romanian IT sector. Among them, the Workforce dimension exhibited the strongest association with SRM quality, highlighting the potential importance of employee engagement, Workforce development, and organisational learning in stakeholder-oriented excellence. The results also support the conceptualisation of SRM quality as a multidimensional construct that emerges from the interaction of complementary organisational subsystems. Although limited by its exploratory nature, sample size, and geographical focus, this study provides an initial foundation for applying the stakeholder-oriented subset of the MBNQA framework to stakeholder relationship management in the Romanian IT sector. Future research should validate the proposed model using larger, more diverse samples and examine its applicability across organisational, industrial, and geographical contexts. Full article

This study investigates the synergistic therapeutic potential of Rivastigmine (RVG) and Epigallocatechin (EGC) in Alzheimer’s disease (AD), a multifactorial neurodegenerative disorder characterized by neuroinflammation, oxidative stress, and dysregulated signaling pathways. Conventional therapies primarily provide symptomatic relief and target limited pathways, highlighting the need for multi-target strategies with improved efficacy and safety. An integrated in silico approach combining pharmacokinetic evaluation, network pharmacology, molecular docking, and molecular dynamics simulations is used to determine the synergistic potential of RVG and EGC. Pharmacokinetic analysis indicates favorable drug-likeness and acceptable ADME/Tox profiles for both compounds. Network pharmacology identified 146 overlapping targets associated with AD, highlighting key hub genes including NFKB1, MAPK1, STAT1, PRKACA, GRB2, LYN, and PTPN11, which are involved in neuroinflammation, synaptic signaling, and neuronal survival. Functional enrichment analysis indicated significant involvement of MAPK/ERK signaling and immune-regulatory pathways. Importantly, the PD-1/PD-L1 signaling pathway is identified as a novel mechanism connecting neuroimmune modulation with intracellular kinase-driven neurodegeneration. Molecular docking studies showed strong binding affinities of RVG and EGC toward key AD-related targets, particularly MAPK1, supported by stable hydrogen bonding and interaction profiles. Molecular dynamics simulations confirmed stable protein-ligand interactions, with EGC contributing structural stability and RVG exhibiting adaptive flexibility within the binding pocket. These results suggest that the RVG-EGC combination exhibits synergistic potential by simultaneously modulating neuroinflammatory, oxidative stress, and kinase-mediated signaling pathways. The integration of PD-1/PD-L1 and MAPK/ERK signaling provides a novel mechanistic pathway for multi-target therapeutic intervention in AD. Full article

In this paper, we introduce and study Hermite–Kampé de Fériet Hahn–Appell polynomial sequences (HKdF Hahn–Appell sequences) within the unified framework of the Hahn difference operator. We establish three equivalent characterisations of these sequences: an operational definition via the Hahn difference condition, an explicit summation formula involving $\alpha$-binomial coefficients and the falling Hahn basis, and a generating-function criterion. A three-term recurrence relation, a second-order difference equation, and the determinantal representation are also derived for these polynomials. The d-orthogonality of the family is characterised via truncation conditions on the recurrence coefficients $\left\{{\sigma }_k\right\}$; the generating functions of d-orthogonal members are identified as products of $\alpha$-Pochhammer symbols, and the d-dimensional functional vector is expressed in closed form. As principal examples, the HKdF Hahn–Bernoulli, HKdF Hahn–Euler, and HKdF Hahn–Genocchi polynomial sequences are introduced, and for each family, four limiting cases are established. A unifying summary table is provided. Graphical and numerical analysis of the zero distribution for all three families confirms the analytical results and illustrates the convergence of zeros to the classical Hermite–Kampé de Fériet setting as the parameters approach their limiting values. Full article

This study investigates the tribological performance of gum arabic (GA)-reinforced epoxy (EP) overlays on EN8 steel. Four GA concentrations (0.25, 0.5, 1, and 3 wt.%) were incorporated into the epoxy matrix to prepare overlays designated as EPGA1–EPGA4. Tribological performance was evaluated using a reciprocating tribometer under varying loads (5–20 N), sliding frequencies (1–2.5 Hz), and temperatures (40–70 °C). An L16 orthogonal array based on the Taguchi method was used to design the experimental matrix, and multi-criteria decision-making using the TOPSIS technique was employed to identify the optimum tribological condition based on minimum coefficient of friction (COF) and specific wear rate (SPWR). The optimum condition was obtained for the EPGA3 overlay (1 wt.% GA) at 5 N, 2 Hz, and 60 °C, which exhibited the lowest COF of 0.0567 ± 0.0021 and negligible wear. In contrast, the pure epoxy overlay showed severe adhesive wear, catastrophic delamination, a high COF of 1.15 ± 0.0023, and a wear rate of 163 × 10⁻⁸ mm³/Nm. Thermal characterization showed that GA improved the thermal stability and thermal transition behaviour of the epoxy matrix. Thermogravimetric analysis revealed an increase in onset degradation temperature from 320 °C for pure EP to 342 °C for EPGA4, while differential scanning calorimetry showed that EPGA3 exhibited the highest glass transition temperature (~118 °C), indicating improved interfacial interactions and restricted polymer-chain mobility. Nanoindentation and pull-off adhesion tests further confirmed the improved mechanical integrity and interfacial adhesion of the GA-reinforced overlays, demonstrating its potential as a sustainable reinforcement for tribological coating applications. Full article

Effective solar receiver design is pivotal to improving the efficiency of concentrated solar collectors, thereby advancing sustainable energy development. This study investigates the impact of receiver configuration on the thermal and exergy performance of parabolic trough collectors and proposes adopting a commercially available copper-finned tube as the receiver. Notably, thermal efficiency improved when the flat corrugated fin was redesigned into an arc-shaped thin-profile configuration. Specifically, the arc-shaped fin receiver outperformed its flat-fin counterpart, achieving thermal efficiencies of 75.8% and 68.5% at a mass flow rate of 0.1 kg/s, respectively. At a lower flow rate of 0.033 kg/s, peak water temperatures of 80 °C and 72 °C were recorded for the arc-shaped and flat-fin receivers, respectively. Comparative analysis further revealed that the arc-shaped fin yielded an average heat transfer coefficient 19–33.9% higher than that of the flat-fin receiver. Furthermore, at 0.033 kg/s, the arc-shaped fin demonstrated superior exergy efficiency, with peak and average values of 7.2% and 4.2%, respectively, compared with 5.2% and 3.0% for the flat-fin receiver. These findings highlight the potential of arc-shaped copper-finned tube receivers to optimize parabolic trough collector performance, offering a promising avenue for advancing sustainable energy development. Full article

First-principles calculations were performed to predict the temperature-dependent elastic properties of fcc-disordered Pt–Rh alloys over a range of compositions. Special quasirandom structures (SQSs) were employed to represent the atomic disorder in the fcc solid-solution phase. The vibrational contribution to the free energy was evaluated using the phonon quasi-harmonic approximation, enabling the calculation of finite-temperature free energies and coefficients of thermal expansion for the fcc-disordered Pt–Rh alloys. The elastic stiffness constants at different compositions were determined using the energy–strain method. By combining the calculated thermal expansion coefficients with elastic stiffness data obtained at various volumes, the temperature-dependent elastic stiffness constants of the fcc-disordered Pt–Rh alloys were determined. Full article