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Research Article
The Neutron Lifetime Puzzle and a Tube Test for
Velocity-dependent and Geometry-dependent Contributions
Alexandar Balevsky*
,
Krasimira Ivanova
Issue:
Volume 15, Issue 3, June 2026
Pages:
71-76
Received:
9 April 2026
Accepted:
21 April 2026
Published:
29 April 2026
Abstract: This article presents a conservative phenomenological framework for discussing the free-neutron lifetime discrepancy in terms of possible geometry-dependent transport and storage contributions superposed on a common intrinsic time scale. The purpose is not to replace the standard weak-decay description, but to formulate an experimentally testable discriminator capable of separating predominantly velocity-dependent from configuration-dependent effects in the extraction of the neutron lifetime. As a starting point, a compact intrinsic-scale layer is used to introduce a working reference value τ₀ ≈ 877.77s. On top of this baseline, two effective correction channels are added. The first is a weak transport or alignment term for a straight tube geometry, suppressed in first approximation approximately as 1/v2. The second is a configuration-mixing term associated with storage or bottle setups, isotropization, and wall-induced scrambling. This leads to a direct and testable expectation: in one and the same straight decay-tube geometry, measurements across a broad speed interval should show either near constancy or only a weak residual speed dependence, whereas larger deviations would point more naturally to storage-specific mixing effects. The formulation is intentionally moderate. It is not presented as derived from QED, nor as a replacement for the standard theory of beta decay. Instead, it is proposed as an effective test framework written in notation-compatible form with respect to the standard operator language and directed toward a concrete straight-tube experiment.
Abstract: This article presents a conservative phenomenological framework for discussing the free-neutron lifetime discrepancy in terms of possible geometry-dependent transport and storage contributions superposed on a common intrinsic time scale. The purpose is not to replace the standard weak-decay description, but to formulate an experimentally testable d...
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Research Article
Numerical Simulation of Time Domain Thermoacoustic Wave Equation Using the FDTD Method with Comparison to the k-Space Pseudospectral Approach
Ujjal Mandal*
Issue:
Volume 15, Issue 3, June 2026
Pages:
77-85
Received:
26 March 2026
Accepted:
8 April 2026
Published:
7 May 2026
DOI:
10.11648/j.ajmp.20261503.12
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Abstract: This study presents a comprehensive numerical investigation of thermoacoustics (TA) wave propagation in the time domain using the Finite Difference Time Domain (FDTD) method, with a comparative analysis against the k-space pseudospectral approach. The TA wave equation is modeled under the assumptions of homogeneous, lossless, and isotropic medium, incorporating a physically realistic source term. A Gaussian initial pressure distribution is employed as the primary excitation, and the resulting acoustic signals are recorded using point and multi-sensor configurations. The study systematically the influence of spatial grid resolution and the Courant-Friedrichs-Lewy (CFL) number on numerical stability and accuracy. It is observed that maintaining a constant CFL number ensures consistent wave propagation behavior across different grid resolutions, whereas variations in CFL lead to significant discrepancies in amplitude and phase of the propagated signals. In addition to Gausian sources, various realistic source geometries, including circular disk, Chebyshev polynomial-based, and asymmetric (rock-like) distributions, are investigated to analyze their impact on wavefield characteristics. The numerical results demonstrate strong agreement between the FDTD and k-space method in both time and frequency domains under stable conditions. However, deviations are observed at higher frequencies due to numerical dispersion effects, particularly in the FDTD scheme. Furthermore, it is shown that sharp discontinuities in binary image based sources introduce non-physical high-frequency components, resulting in spurious oscillations. This study highlights the importance of numerical parameter selection, particularly the CFL condition, and provides a detailed comparision of two widely used computational methods for TA wave simulation. The findings offer valuable insights into the role of source geometry and numerical schemes in accurately modeling acoustic wave propagation.
Abstract: This study presents a comprehensive numerical investigation of thermoacoustics (TA) wave propagation in the time domain using the Finite Difference Time Domain (FDTD) method, with a comparative analysis against the k-space pseudospectral approach. The TA wave equation is modeled under the assumptions of homogeneous, lossless, and isotropic medium, ...
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Research Article
Modeling of Coupled Heat and Mass Transfer for the Optimization of Evaporative Cooling Using a Porous Clay Plate
Issue:
Volume 15, Issue 3, June 2026
Pages:
86-95
Received:
14 April 2026
Accepted:
27 April 2026
Published:
12 May 2026
DOI:
10.11648/j.ajmp.20261503.13
Downloads:
Views:
Abstract: This study investigates the complex mechanisms of coupled heat and mass transfer within a fired porous clay plate optimized for evaporative cooling in hot and dry climates. The primary objective was to model and experimentally validate the material's ability to lower air temperature through capillary evaporation. Local results highlight a pronounced leading-edge effect, where a maximum evaporation flux of 0.78 g/m² induces rapid cooling within the first few centimeters of the plate. Under nominal conditions of 40°C and 20% relative humidity (RH), the outlet air temperature drops significantly to 25.38°C, corresponding to a thermal gain of nearly 15°C. The theoretical validity of the model is confirmed by the perfect superposition of local Nusselt (Nux) and Sherwood (Shx) numbers, demonstrating the consistency of the Chilton-Colburn analogy. Parametric analysis reveals that system efficiency is highly dependent on residence time and hygrometric potential: a moderate air velocity of 1.5 m/s combined with low initial humidity (10%) optimizes the process, achieving a record cooling of 17.4°C. Despite some simplifying assumptions (adiabatic walls, uniform saturation), comparison with experimental data shows excellent agreement, with an average relative error of 6% to 7% and a root mean square error (RMSE) of approximately 2°C. The research demonstrates that fired clay, owing to its porous structure that promotes capillary transport, constitutes an efficient passive heat exchanger and a sustainable alternative to energy-intensive air conditioning systems.
Abstract: This study investigates the complex mechanisms of coupled heat and mass transfer within a fired porous clay plate optimized for evaporative cooling in hot and dry climates. The primary objective was to model and experimentally validate the material's ability to lower air temperature through capillary evaporation. Local results highlight a pronounce...
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