Asian Journal of Research and Reviews in Physics

The CRAL Model: A Theoretical Framework for Culturally-responsive, Inquiry-based Physics Instruction in Nigerian Secondary Schools

Emmanuel C. Hemba — 2026-09-24

Introduction: Physics instruction in Nigerian secondary schools often fails to connect abstract concepts to students’ lived realities, limiting genuine understanding and engagement.

Objectives: This paper introduces and theorises the Concrete-Representational-Abstract-Lived-Experience (CRAL) Model, a novel pedagogical framework that anchors physics instruction in community-level cultural specificity.

Methods: CRAL extends the established Concrete-Representational-Abstract progression from mathematics education with a fourth stage — Lived-Experience Localisation — in which students explain physics concepts through analogies drawn from their immediate instructional community. The framework is embedded within the 5E inquiry cycle and grounded in constructivist learning theory, conceptual change theory, culturally responsive pedagogy, and analogical reasoning. CRAL is operationalised through PhysicsMentor-NG, an AI-powered lesson generation system that structurally enforces community-level cultural specificity.

Results: As a theoretical paper, no empirical data were collected; the outcomes below are analytic, not measured. The framework yields lesson designs in which cultural grounding is a structural requirement rather than a pedagogical suggestion, and PhysicsMentor-NG enforces this requirement consistently in the lesson notes it generates.

Conclusions: CRAL represents a practical and deployable innovation for Nigerian secondary science education, with broader applicability across postcolonial, multilingual school systems.

Statistical Approaches to Environmental and Atmospheric Influences on Fifth-generation Mobile Signal Propagation in Tropical Regions: A Critical Review

Sirajo Abdullahi — 2026-09-02

Tropical and equatorial territories combine the most intense sustained rainfall on the planet with an accelerating rollout of fifth-generation mobile networks in the centimetre and millimetre wave bands. The statistical apparatus used to translate environmental and atmospheric measurements into propagation predictions, however, was assembled largely from temperate-latitude datasets and from fixed links considerably longer than the urban small cells that dominate contemporary deployment. This review critically evaluates how statistical methods have been applied to environmental and atmospheric parameters governing fifth-generation propagation in the tropics, and asks whether the resulting evidence supports the confidence routinely placed in it. Five method families are examined: the estimation of point rainfall rate distributions and the conversion of long integration-time records to the one-minute reference; the regression of specific attenuation on rainfall rate through power-law coefficients derived from drop size spectra; the spatial statistics embedded in path reduction factors, effective rainfall rate formulations and site diversity models; the correlational and regression treatment of water vapour, temperature, refractivity, wind and vegetation; and supervised learning applied to path loss and attenuation time series. Convergent evidence establishes that rainfall rates exceeded for one hundredth of one per cent of an average year in equatorial sites are roughly an order of magnitude above temperate values, and that standard international recommendations systematically misestimate attenuation on paths shorter than one kilometre. Beyond this, the evidence weakens sharply. Reported model rankings rest on single-year records from a small number of sites, are assessed with inconsistent error statistics and almost never carry uncertainty intervals, so apparent superiority is frequently indistinguishable from sampling variation. Studies of non-precipitation parameters report correlations that reverse sign between seasons and regression models that explain little of the observed variance, yet these are often interpreted causally. Machine learning results are constrained by small, spatially autocorrelated datasets, by evaluation protocols that permit optimistic bias, and in some cases by reliance on simulator output as ground truth. Progress requires coordinated multi-site campaigns, open data, formal uncertainty quantification and validation protocols that test transfer rather than fit.

Application of Artificial Intelligence in Satellite Orbit and Clock Correction: A Review

Azeez Ibraheem Abiodun — 2026-09-08

Aims: This review examines AI-assisted methods for satellite orbit determination and prediction, clock-bias forecasting, thermospheric-density calibration, atmospheric-delay modelling, and integrated GNSS correction. It identifies recurrently successful approaches, limitations in the current evidence, and priorities for future research.

Study Design: A structured narrative synthesis of foundational and recent literature published through early 2026 was undertaken. Targeted keyword searches and backward citation checking were used to identify studies of classical machine learning, recurrent and attention-based networks, ensembles, graph neural networks, and physics-informed neural networks. Evidence was organised by task, data regime, baseline, forecast horizon, metric, and reported limitation; no pooled meta-analysis was performed.

Results: Across the reviewed orbit studies, hybrid residual-learning schemes were the most recurrently successful design, although no pooled effect was estimated. In one thermospheric-density evaluation, AI calibration improved mean absolute percentage error by 61% against NRLMSISE-00 and 39% against JB-08. In one one-day GPS clock experiment, QP-assisted BPNN, WNN, LSTM, and GRU models improved on quadratic polynomial prediction by about 39%, 58%, 27%, and 29%, respectively. In a separate four-city dataset, a graph-based model reduced horizontal positioning error by 40-80% relative to the tested deep-learning baselines. These values are study-specific, not general effect estimates. Common barriers were limited cross-satellite generalisation, scarce precise LEO data, computational constraints, weak uncertainty calibration, and separate orbit and clock pipelines.

Conclusion: AI can improve specific parts of the orbit and clock correction chain when models are evaluated against suitable physical or statistical baselines. The evidence favours transferable, physics-informed, uncertainty-aware, and computationally efficient joint models, supported by common benchmarks and independent validation.

Analysis of Lamé's Parameters in Clastic Reservoirs of Differing Quality: A Case Study of Stacked Channel Sands in the Akau Field, Central Swamp, Niger Delta

Sonny Inichinbia — 2026-09-19

This study focuses on the analysis of Lamé’s parameters in clastic rocks of different reservoir quality in the Akau field of the Central Swamp, Niger Delta. Two channel-reservoir models filled with sands of different geological ages and located at different depths were considered to investigate reservoir heterogeneities. The channel sands are of different reservoir quality, differing in their shale content and porosity. Three Gassmann fluid-substitution cases (brine, oil, and gas) were analysed. In each case, compressional- and shear-wave impedances and Lamé parameters were calculated. Interpretation of well-log data was based on crossplots of elastic parameters, allowing differentiation of reservoir sands from shale intervals and other lithofacies. The porosity of the reservoirs ranges from 18–30%; µρ values range from 1.5e+13-2.5e+13 units, λρ values for the oil case range from 1.5e+13–2.0e+13 units, and µρ values for the gas case range from 1.5e+13–1.8e+13 units. The oil case shows µρ values of 1.6e+13 – 1.7e+13 units, which are less than λρ. Changes in porosity with respect to µρ occur at a much faster rate than changes in porosity with respect to λρ. It can be seen that µρ is a more sensitive parameter for fluid detection over a wide range of porosity despite a relatively small range of elastic parameters. As a result, µρ is a more reliable parameter for fluid detection in reservoirs with different sand properties. Combining well-log and 3D pre-stack seismic data collected in the study area enabled high-resolution lithology and fluid characterisation, allowing lithology classification, fluid detection, and separation of fluids in porous reservoir sands. The major lithologies were sand and shale, while the fluids included gas, oil, and brine.

Evaluation and Calibration of Downward Longwave Radiation Models under Clear Sky Condition across the Sahelian Region of Nigeria

Davidson Odafe Akpootu — 2026-09-01

Downward longwave radiation (DLR) is a major component of the surface energy budget, yet the transferability of empirical clear-sky DLR models across Nigeria’s Sahelian climatic zone remains uncertain. This study evaluated eleven existing empirical DLR models and five locally calibrated modifications for Kano and Sokoto. Monthly mean relative humidity, air temperature, and DLR data covering 1984–2023 were used, with 1984–2015 allocated to model development and 2016–2023 reserved for validation. Model performance was assessed using Mean Bias Error, Root Mean Square Error, Mean Percentage Error, t-test, Index of Agreement, correlation coefficient for the modified models, and an overall ranking procedure. Among the existing models, the Idso formulation ranked first at both locations. For Kano, the modified Guest model was the best-performing calibrated model and also ranked ahead of the existing Idso model in the direct comparison. For Sokoto, the modified Idso model ranked first among the calibrated models; however, the existing Idso model retained the better overall rank in the direct comparison. Seasonal analysis showed higher DLR during the rainy season and lower values during the dry Harmattan season, with relative humidity and atmospheric moisture varying concurrently with DLR. The results indicate that local calibration can improve empirical DLR estimation, although the benefit depends on location and model formulation.

Empirical Measurement of 5G Mobile Signal Path Loss in Southern and Northern Urban Metropolis of Nigeria

Sirajo Abdullahi — 2026-09-03

Accurate characterisation of large-scale radio attenuation is important for fifth-generation (5G) network planning, particularly in heterogeneous urban environments. This study reports a drive-test assessment conducted in Lagos and Ibadan in southern Nigeria and Abuja and Kano in northern Nigeria at 3.5-3.6 GHz. The reported measurement configuration used a receiver height of 1.5 m, a transmitting-antenna height of approximately 40-45 m, and transmitter-receiver separations of about 50-500 m. Reference Signal Received Power, Reference Signal Received Quality, signal-to-noise ratio, throughput, and Global Positioning System coordinates were logged using TEMS Investigation, a 5G signal analyser, and a vehicle-mounted measurement setup. A locally calibrated log-distance relation with city-specific intercept terms was graphically juxtaposed with Okumura-Hata, COST-231 Hata, Egli, and the ITU-R P.833-9 vegetation-attenuation formulation. The plots show substantial divergence among model families and among city/operator panels, demonstrating that model choice and local calibration assumptions materially affect predicted attenuation trends. The ITU-R P.833-9 series is interpreted only as a vegetation-attenuation benchmark rather than a complete urban path-loss model. The results do not support a universal north-south ranking of propagation loss; instead, they indicate site-, route-, and configuration-dependent behaviour. Because complete route-level residuals, uncertainty estimates, and all fitted model parameters are not available for every panel, the comparison is intentionally descriptive and does not claim statistical superiority of one model. The findings support cautious, measurement-informed calibration of 5G propagation models for Nigerian urban deployments.

Influence of Electron Beam Irradiation on the Structural, Optical, and Electrical Properties of Ag₂Se Thin Films

V. G. Kurundkar — 2026-09-04

The present work aims to investigate the effect of electron irradiation on the properties of silver selenide thin films. In this work, dendritic Ag₂Se thin films were synthesised via a facile, low-cost potentiostatic electrodeposition technique on fluorine-doped tin oxide (FTO) glass substrates. Silver nitrate (AgNO₃) and selenium dioxide (SeO₂) were employed as precursor sources, while ethylenediaminetetraacetic acid (EDTA) served as a complexing agent to regulate ion release and crystal growth (5 mM AgNO₃ + 2.5 mM SeO₂ + 0.05 M EDTA). The phase composition, crystallographic structure, surface morphology, and optical properties of the deposited films were systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical absorption spectroscopy. XRD analysis confirmed the formation of crystalline Ag₂Se without detectable secondary phases, whereas SEM revealed the evolution of highly branched dendritic architectures with well-defined fractal characteristics. Optical studies demonstrated the characteristic absorption behaviour of Ag₂Se, indicating its suitability for semiconductor-based applications. Furthermore, the growth mechanism of the dendritic structures was explained through a comparative investigation of the as-deposited films and those subjected to electron-beam irradiation, providing insights into the role of diffusion-limited growth and post-deposition structural evolution. The present electrodeposition strategy offers a scalable and energy-efficient route for fabricating Ag₂Se dendritic thin films with controlled morphology, opening new opportunities for their integration into advanced optoelectronic, thermoelectric, and energy-conversion devices.

Integrated Human Health and Radiological Risk Assessment of Heavy Metals and Naturally Occurring Radionuclides in Soil and Water from Oil

Sanda Yusuf Sadau — 2026-09-08

Oil and gas exploration can both introduce and redistribute potentially toxic metals and naturally occurring radioactive material across the soils and water bodies of surrounding communities, opening exposure pathways that reach well beyond the immediate production site. This study evaluated the human-health risk from heavy metals and the radiological risk from naturally occurring radionuclides in soil and water sampled from the Apkai and Umusedege oil-field communities in Ndokwa East and Ndokwa West Local Government Areas of Delta State, Nigeria. Sixty-three soil samples and eleven water samples were analysed using atomic absorption spectrophotometry, X-ray fluorescence spectroscopy, gross alpha/beta counting and gamma-ray spectrometry, covering Ni, Cr, Cu, Co, Pb, Cd, Fe, Mn, As and Zn. Human-health risk was modelled for children and adults using USEPA exposure equations across ingestion, inhalation and dermal-contact pathways; the pathway-level components were audited directly against their own reported totals by direct summation of their reported pathway contributions. Once audited, the combined soil-and-water hazard index came to 2.53 for children and 13.60 for adults, with ingestion the dominant soil pathway for both groups and an unusually large adult water-dermal contribution driving the adult total; both hazard indices exceed the HI = 1 screening threshold. Total excess lifetime cancer risk from heavy-metal exposure was 7.18×10⁻⁶ for children and 2.40×10⁻⁶ for adults, both remaining within the USEPA-adopted acceptable range. In water, gross alpha and beta activities averaged 1184 and 2164 mBq L⁻¹ respectively, peaking at 3160 and 6145 mBq L⁻¹, with corresponding mean annual effective doses of 2.154, 1.133 and 0.566 mSv y⁻¹ (alpha) and 4.087, 2.106 and 1.053 mSv y⁻¹ (beta) for adults, children and infants respectively. Gamma spectrometry of soil gave mean activity concentrations of 36.102 Bq kg⁻¹ for ²²⁶Ra, 50.237 Bq kg⁻¹ for ²³²Th and 251.903 Bq kg⁻¹ for ⁴⁰K, with a mean absorbed dose rate of 42.22 nGy h⁻¹, annual effective dose of 0.076 mSv y⁻¹ and radium equivalent activity of 91.627 Bq kg⁻¹. Mean external hazard, internal hazard, gamma representative-level and alpha indices were 0.247, 0.335, 0.376 and 0.162 respectively, and the calculated radiological cancer risks were 3.18×10⁻⁶ for adults and 4.32×10⁻⁶ for the whole population. Taken together, the audited results point to heavy-metal exposure with elevated hazard indices for both children and adults as the primary human-health concern, while soil NORM levels imply comparatively low external radiological hazard. Water, in contrast, showed elevated gross alpha/beta activity and associated doses alongside the dominant adult dermal hazard quotient, and therefore warrants continued radiological and chemical monitoring, more targeted radionuclide-specific follow-up, and independent verification of the adult water-dermal exposure calculation.

Radiological Characterization of Dredged Sediments from the Nun River, Nigeria, and their Implications for Building Material Use

Ugochukwu Nkajoe — 2026-09-11

This study assesses the radiological safety of sediments obtained from dredging activities along the Nun River, Bayelsa State, Nigeria, where such materials are commonly used in residential construction. Given the potential contribution of naturally occurring radionuclides in building materials to indoor radiation exposure, the study is guided by radiation protection principles aimed at minimising exposure to ionising radiation. Sediment samples from ten locations in two Local Government Areas were analysed using a NaI(Tl) gamma spectrometry system. This study is the first extensive radiological characterisation of dredged sediments from the Nun River, Nigeria, and provides a critical baseline for the Niger Delta region. The mean activity concentrations of ⁴⁰K (402.22 Bq/kg) and ²³⁸U (28.10 Bq/kg) were within the limits set by UNSCEAR, whereas ²³²Th (6.04 Bq/kg) was significantly below the corresponding limit, a pattern characteristic of the mineralogy of the Niger Delta. The radiological hazard indices, including Raeq (mean 67.71 Bq/kg), Hₑₓ (mean 0.18), Hᵢₙ (mean 0.24), and Iγ (mean 0.50), were all below the internationally recommended safety limits. The gamma index (Iγ) ranged from 0.24 to 0.91, indicating that most Nun River sediments meet the initial screening criterion for use in construction applications. Multiple linear regression revealed that ⁴⁰K contributed the most to the variability of Iγ (β=0.486), followed by ²³⁸U (β=0.386) and ²³²Th (β=0.262); the model fit was excellent. Shared mineralogical controls were further suggested by strong correlations among the radionuclides. The results, particularly the hazard indices and Iγ, were well below unity, indicating that the sediments pose negligible indoor exposure risks.

A Unified Framework of Digital Synthesis of Chebyshev and Elliptic Filter Using Frequency Domain and Bilinear Transform for 5G Applications

Aruekure Miracle Diebogheneruo — 2026-09-24

Digital filtering in 5G front ends requires a design procedure that permits direct comparison of filter families under identical specifications. This study presents a unified comparative workflow for synthesising Chebyshev Type I and Elliptic digital filters using frequency-domain transformations followed by the bilinear transform. The filters were designed from matching low-pass prototypes with a sampling frequency of 40 GHz, a 12 GHz passband edge, a 15 GHz stopband edge, a maximum passband ripple of 0.1 dB, a minimum stopband-attenuation target of 60 dB, and a matched order of 14. Each prototype was transformed into High-Pass, Band-Pass, and Band-Stop configurations and then converted into the digital domain. Frequency response, phase response, group delay, impulse response, transition bandwidth, and stopband attenuation were evaluated using Python, SciPy, and Matplotlib. The digital Elliptic designs produced stopband attenuations of 72.8, 76.8, and 74.3 dB for the High-Pass, Band-Pass, and Band-Stop configurations, respectively, whereas the corresponding Chebyshev values were 58.3, 59.4, and 59.8 dB. The Elliptic filters also exhibited narrower transition regions, while the Chebyshev filters showed comparatively more favourable phase behaviour and simpler implementation characteristics. These results indicate that the two filter families provide complementary performance under the stated design conditions, supporting application-specific selection according to rejection, transition-band, phase, and delay requirements in 5G digital front ends.

Comparative Reanalysis of 89.9 MHz Click FM Path Loss on the IBB University Campus Using Parabolic-equation and Empirical Models

B. Ndanusa — 2026-10-03

This study presents a comparative reanalysis of distance-indexed path-loss data for the 89.9 MHz Click FM signal within Ibrahim Badamasi Babangida University (IBBU), Lapai, Nigeria. The analysis evaluates a parabolic-equation (PE) prediction series against the Free Space Path Loss (FSPL), Ericsson, and Lee comparator series using the 12-measured path-loss values reported for transmitter-receiver separations from 50 to 600 m. To ensure internal consistency, all error statistics were recomputed directly from the values in Table 1 and the graphical results were regenerated from the same dataset. The full-dataset root means square errors (RMSEs) were 15.39 dB for the PE series, 30.55 dB for Ericsson, 35.31 dB for Lee, and 79.83 dB for FSPL. The corresponding mean absolute errors were 11.46, 26.27, 31.65, and 78.28 dB, respectively. Within this 12-point dataset, the PE series therefore shows the closest overall agreement with the measured path loss, while still smoothing several strong local fluctuations in the observations. A cumulative RMSE analysis is also reported as a descriptive measure of how prediction error evolves as progressively more distance points are included. Because the available data are a secondary distance-indexed series rather than the complete route-level measurement archive, the findings are interpreted as a within-dataset comparison rather than evidence of universal model superiority. The results support further independently documented VHF field validation of PE-based propagation prediction in campus environments.

Performance of International Reference Ionosphere-2016 and NeQuick-2 Models in Estimating Global Positioning System Total Electron Content Over a Nigerian Equatorial Station during Two Phases of Solar Cycle 24

Eugene O. Onori — 2026-10-05

Aim: This study examines the temporal behaviour of GPS-derived total electron content (GPS-TEC) and evaluates the capability of the International Reference Ionosphere-2016 (IRI-2016) and NeQuick-2 models to reproduce observed ionospheric conditions over Birnin Kebbi, Nigeria (12.64° N, 4.22° E; dip latitude 2.68° N).

Methods: The analysis considers 2011 and 2014, representing the ascending and maximum phases of Solar Cycle 24, respectively. Dual-frequency GNSS observations were processed to vertical TEC (VTEC), and corresponding model estimates were obtained from IRI-2016 and NeQuick-2. Monthly mean diurnal data were grouped into four seasons: March equinox, June solstice, September equinox and December solstice. Model disagreement was quantified using mean absolute error (MAE).

Results: GPS-TEC increased from pre-sunrise values to daytime maxima and decreased after sunset. Observed maxima generally occurred at 13:00–15:00 LT and had a dome-shaped profile, whereas the models frequently produced an earlier maximum and a noon-depression or double-peaked structure. June-solstice TEC was consistently lower than the other seasonal groupings. IRI-2016 had the lower MAE in most seasonal comparisons; NeQuick-2 showed a slightly lower MAE only during the December solstice of 2011.

Conclusion: IRI-2016 provided the closer climatological representation for most of the cases examined, but neither model reproduced all features of the observed local-time and seasonal behaviour. The findings support the need for regional validation of empirical ionospheric models over the Nigerian equatorial sector.

Breaking the Limit of Seismic Resolution to Enhance Channel Sand Delineation from Seismic Data for Deep Gas Development

Sonny Inichinbia — 2026-10-05

Characterising channel gas sands in the Chua field of the Central Swamp, Niger Delta, is constrained by the limited vertical resolution of seismic data and by overlapping P-impedance values between gas sands and gas shales. This study integrates long-cable anisotropic 3D seismic data with well-log information to improve subsurface layer resolution, delineate channel-sand reservoirs, and discriminate lithology and fluid content. Amplitude-versus-offset analysis of pre-stack seismic data was combined with layer-based inversion, rock-physics constraints, spectral decomposition, coherence, and curvature attributes. The results show that S-impedance inversion provided better separation of gas sands and gas shales than P-impedance inversion. The observed amplitude anomalies were associated with hard sands having higher Vp/Vs ratios than the fluid-line Vp/Vs ratio in intercept-gradient space. Shale interference caused seismic amplitudes to reflect gross reservoir thickness more strongly than direct net-pay thickness. Interpretation of the integrated data also delineated extensive braided fluvial channel systems, with interpreted sand thicknesses ranging from approximately 85 to 120 m. The combined workflow improved characterisation of channel geometry and reservoir distribution where conventional impedance interpretation alone was insufficient. The findings indicate that integrating pre-stack seismic analysis, elastic inversion, well information, and complementary seismic attributes can support more reliable delineation of deep gas channel sands in the Chua field.

Self-Reported Health Outcomes and Time Spent Near Telecommunication Base Stations in Ilesa East and Ilesa West Local Government Areas, Osun State, Nigeria: A Cross-Sectional Study

Olawale Sunday Asabi — 2026-10-14

Aims: To examine the association between time spent near telecommunication base stations and self-reported health outcomes among residents of Ilesa East and Ilesa West Local Government Areas, Osun State, Nigeria, and to describe health-worker observations from facilities serving the same communities.

Study Design: A Cross-sectional descriptive survey.

Place and Duration of Study: Thirteen telecommunication mast sites across seven wards and eight health facilities in Ilesa East and Ilesa West Local Government Areas, Osun State, Nigeria; fieldwork was conducted from July 2025 to March 2026.

Methodology: A 21-item questionnaire was administered to 261 community respondents selected through purposive and convenience sampling from clusters around 13 masts, and a 17-item questionnaire was administered to all 17 consenting health workers (total enumeration). Exposure was operationalised as self-reported time spent around the mast; no RF-EMF field-strength measurements were taken. Data were analysed in SPSS using frequencies and percentages and, for the association between time spent around the mast and reported fatigue, a chi-square test of independence at a significance level of 0.05.

Results: Female respondents constituted 59.00% of the community sample, and artisans were the largest occupational group (37.16%). Mast-associated noise was reported by 60.92% of respondents. Self-reported outcomes included regular headache (6.51%), cancer-related disease (22.61%), sensation of internal heat (3.45%), congenital malformation or behavioural problems in children (2.30%), childhood leukaemia (1.15%), miscarriage (4.98%), abnormal night sleep (24.14%), fatigue (30.27%), and eye problems (21.07%). Fatigue prevalence did not rise with time spent around the mast (26.88% in the 12–24 h group, 31.51% in the < 12 h group, and 32.63% in the occasional-exposure group), and the association was not statistically significant (χ²(2, N = 261) = 0.81, p = .667). Among the 17 health workers, 3 (17.65%) reported having encountered a cancer-related case and 1 (5.88%) a miscarriage case that they attributed to mast proximity, while 11 (64.71%) reported other health problems seen at their facilities. These are reports of cases encountered, not individually verified diagnoses and are not comparable with residents' reports of their own conditions. All 261 community respondents and all 17 health workers recommended against siting masts close to residential buildings.

Conclusion: Residents near telecommunication masts in the Ilesa area reported non-specific symptoms, particularly fatigue and sleep disturbance, and lower-frequency reports of cancer-related disease and miscarriage. Time spent around the mast was not significantly associated with reported fatigue. Health-worker observations are complementary and do not independently verify residents' conditions. The cross-sectional, self-reported design, without field-strength measurements cannot establish a causal RF-EMF relationship. The unanimous preference for siting masts away from residences supports enforcement of existing siting standards, objective RF-EMF monitoring, and community consultation before mast installation.

A Proof-of-Concept Study of Meat Broth Classification Using UV–Vis Spectroscopy and Explainable Decision Tree Analysis

Stanly Gabriel — 2026-10-15

Background: Rapid discrimination of animal-derived food products is relevant to food authenticity, consumer protection, and dietary compliance. UV–Vis spectroscopy provides a simple analytical approach for obtaining optical fingerprints of food matrices; however, spectral interpretation may benefit from transparent machine-learning methods.

Objective: This proof-of-concept study investigated the feasibility of combining UV–Vis spectrophotometry with an interpretable Decision Tree classifier to discriminate chicken, pork, and beef broths and to identify wavelength variables contributing to classification.

Methods: Broths prepared from chicken, pork, and beef were analyzed by UV–Vis spectrophotometry in the 244.5–249.0 nm spectral region, yielding 10 wavelength-specific absorbance variables. Two predesignated datasets were used: 15 training observations (five per class) and 15 test observations (five per class). Model development used only the training dataset. Because 10-fold stratification is not feasible with only five observations per class, shuffled 10-fold KFold cross-validation (random_state = 42) was applied to the training data. A Decision Tree classifier using Gini impurity was evaluated by accuracy, macro-precision, macro-recall, macro-F1, out-of-fold (OOF) confusion matrix, and multiclass one-vs-rest ROC-AUC. The final tree was then fitted to all training observations and evaluated once on the untouched test dataset. Feature importance and SHAP values were used for model interpretation. No feature scaling was applied to Decision Tree modeling.

Results: All 10 validation folds were classified correctly, producing mean cross-validation accuracy, macro-precision, macro-recall, and macro-F1 of 1.000 ± 0.000. Pooled OOF predictions also yielded accuracy, macro-precision, macro-recall, macro-F1, and multiclass OvR ROC-AUC of 1.000. The final Decision Tree had a depth of two and three terminal leaves. On the separately designated 15-observation test dataset, all observations were correctly classified (confusion matrix diagonal: 5, 5, and 5), with accuracy, macro-precision, macro-recall, macro-F1, and macro OvR ROC-AUC all equal to 1.000. Feature importance was concentrated at 245.5 and 248.5 nm (0.50 each), and SHAP analysis likewise identified these wavelengths as the dominant model contributors. These perfect metrics must be interpreted cautiously because the observations are technical replicates from a very limited number of broth preparations.

Conclusion: The findings demonstrate the feasibility of integrating UV–Vis spectroscopy with an interpretable Decision Tree for preliminary discrimination of chicken, pork, and beef broth spectra. Under the present proof-of-concept dataset, the model achieved perfect 10-fold OOF and separately designated test-set classification, with 245.5 and 248.5 nm driving the fitted decision rules. However, the technical-replicate structure and very small number of independent broth preparations preclude claims of biological generalization. Validation using larger numbers of independently prepared samples, multiple biological sources and batches, and genuinely external test sets is required before practical food-authentication use can be established.