Time-dependent Measurements Research Articles

Convergence of bi-spatial pullback random attractors and stochastic Liouville type equations for nonautonomous stochastic p-Laplacian lattice system

We consider convergence properties of the long-term behaviors with respect to the coefficient of the stochastic term for a nonautonomous stochastic p-Laplacian lattice equation with multiplicative noise. First, the upper semi-continuity of pullback random (ℓ2, ℓq)-attractor is proved for each q ∈ [1, +∞). Then, a convergence result of the time-dependent invariant sample Borel probability measures is obtained in ℓ2. Next, we show that the invariant sample measures satisfy a stochastic Liouville type equation and a termwise convergence of the stochastic Liouville type equations is verified. Furthermore, each family of the invariant sample measures is turned out to be a sample statistical solution, which hence also fulfills a convergence consequence.

Exploring the role of edges in surface functionalization and stability of plasma-modified carbon materials: Experimental and DFT insights

Effective surface functionalization of carbon nanomaterials plays a crucial role in various applications. We investigated the impact of edges on surface functionalization and stability of oxygen-modified carbon materials using a combination of experimental techniques and Density Functional Theory (DFT) insights. Graphenic paper, highly oriented pyrolytic graphite (HOPG), and graphenic flakes were employed as model systems, with oxygen plasma treatment (generator power 100 W, oxygen pressure 0.2 mbar, exposure time 6 – 300 s) serving as the modification method. Surface morphology and chemical composition were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The results revealed the introduction of oxygen functional groups on the investigated carbon surfaces (up to 20 at % by XPS) whereas; the structural integrity of the materials remained intact upon plasma modification (SEM, Raman). Work function was used as a sensitive parameter for monitoring the surface changes (increase by ∼1.4 eV, 1.3 eV, and 1 eV for graphenic paper, HOPG, and graphenic flakes, respectively) while time-dependent measurements revealed distinct kinetic processes governing the decay of functionalization, highlighting the role of surface defects in post-plasma processes. DFT calculations provided molecular-level insights into the surface processes, elucidating the mechanisms underlying the diffusion of hydroxyls, their recombination, and water desorption. Since the calculated activation barrier for recombination on basal graphenic planes (∼1.0 eV) and edges (∼5.5 eV) are distinctly different, it can be thus concluded that the persistent functionalization is due to the surface edges. Our findings contribute to a deeper understanding of surface modification processes of carbon materials and offer rationales for the design of advanced functional nanomaterials with tailored surface properties.

Engineering the plasmonic activities of copper nanostructures for SERS and photocatalysis

Nanoparticles of plasmonic metals such as gold (Au), silver (Ag) and copper (Cu) have numerous applications due to their localized surface plasmon resonance. Among these, nanoparticles of Cu remain underexplored when compared to Au and Ag, although the former is much cheaper. Here we report the surface enhanced Raman spectroscopy (SERS), interaction of molecule with a plasmonics and photocatalysis applications of Cu nanostructures. Hexagonal and cubic shaped Cu nanostructures were successfully synthesized by varying the reaction conditions in a polyol synthesis method. Rapid nucleation at an elevated temperature (140 °C) and subsequent slow growth at lower temperature (80 °C) in presence of PVP polymeric stabilizer resulted in the formation of uniform cube shaped Cu nanoparticles (Cucube). Whereas polyol synthesis at a low temperature (80 °C) resulted in hexagonal Cu nanoparticles (Cuhex). Cuhex exhibited higher SERS enhancement compared to Cucube. Specifically, Using 532, 633 and 785 nm lasers, Cuhex showed enhancement factor 9.0×105. The detection limit as low as 10-10 M for RhB using Cuhex. Moreover, based on emission and time-dependent measurements, strong molecular and plasmonic interactions reveal energy transfer from RhB molecules to the Cu nanostructures. Additionally, Cuhex showed very good catalytic and visible light plasmonic photocatalytic activities for the para-nitrophenol (p-NP) reduction reaction.

Three-Dimensional (3D) Surface-Enhanced Raman Spectroscopy (SERS) Substrates for Sensing Low-Concentration Molecules in Solution.

The use of surface-enhanced Raman spectroscopy (SERS) in liquid solutions has always been challenging due to signal fluctuations, inconsistent data, and difficulties in obtaining reliable results, especially at very low analyte concentrations. In our study, we introduce a new method using a three-dimensional (3D) SERS substrate made of silica microparticles (SMPs) with attached plasmonic nanoparticles (NPs). These SMPs were placed in low-concentration analyte solutions for SERS analysis. In the first approach to perform SERS in a 3D environment, glycerin was used to immobilize the particles, which enabled high-resolution SERS imaging. Additionally, we conducted time-dependent SERS measurements in an aqueous solution, where freely suspended SMPs passed through the laser focus. In both scenarios, EFs larger than 200 were achieved, which enabled the detection of low-abundance analytes. Our study demonstrates a reliable and reproducible method for performing SERS in liquid environments, offering significant advantages for the real-time analysis of dynamic processes, sensitive detection of low-concentration molecules, and potential applications in biomolecular interaction studies, environmental monitoring, and biomedical diagnostics.

A dynamical optimal control theory and cost-effectiveness analyses of the HBV and HIV/AIDS co-infection model.

Studies have shown that the co-infection of Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV) poses a major threat to the public health due to their combined negative impacts on health and increased risk of complications. Even though, some scholars formulated and analyzed the HBV and HIV co-infection model they did not consider the compartment that contains protected individuals against both HBV and HIV infections. They incorporated the optimal control theory and cost-effectiveness analysis simultaneously. With this in mind, we are motivated to formulate and analyze the HBV and HIV co-infection model, considering the protected group and incorporating optimal control theory and cost-effectiveness. In this study, we have theoretically computed all of the models disease-free equilibrium points, all the models effective reproduction numbers and unique endemic equilibrium points. The two sub-models disease-free equilibrium points are locally as well as globally asymptotically stable whenever their associated effective reproduction numbers are less than one. We reformulated the optimal control problem by incorporating five time-dependent control measures and conducted its theoretical analysis by utilizing the Pontryagin's maximum principle. Using the fourth order Runge-Kutta numerical method and MATLAB ODE45, we performed the numerical simulations with various combinations of control efforts to verify the theoretical results and investigate the impacts of the suggested protection and treatment control strategies for both the HBV and HIV diseases. Also, we carried out a cost-effectiveness analysis of the proposed control strategies. Eventually, we compared our model results with other researcher similar model results whenever cost-effectiveness analysis is not carried out the findings of this particular study suggest that implementing each of the proposed control strategies simultaneously has a high potential to reduce and control the spread of HBV and HIV co-infections in the community. According to the cost-effectiveness analysis, implementing the HBV treatment and the HIV and HBV co-infection treatment measures has a high potential effect on reducing and controlling the HBV and HIV co-infection transmission problem in the community.

Fault diagnosis of floating offshore wind turbine based on bidirectional long short-term memory networks with sliding window

Owing to its ability to harvest more power in deeper waters than other types of offshore wind turbines, the floating offshore wind turbine (FOWT) has attracted significant interest from both academics and industry. However, deterioration in system performance and unscheduled shutdowns will significantly increase operation and maintenance costs. To avoid system damage and ensure operation safety, there is a great demand for developing FOWT fault diagnosis to detect and identify faults as early as feasible. Due to the enormous complexity of FOWT including dynamics and nonlinearity, effective FOWT fault diagnosis poses a significant challenge. This paper develops a novel FOWT fault diagnosis method using bidirectional long short-term memory (BiLSTM) with sliding window. Firstly, the dynamics are embedded by stacking time-dependent measurements using the sliding window technique. Then, the augmented data is fed into a BiLSTM network to exploit the nonlinearity of FOWT. Consequently, a softmax classifier is used for fault diagnosis. A high-fidelity 10 MW spar FOWT benchmark based on the NREL Fatigue, Aerodynamics, Structures, and Turbulence (FAST) model is used to validate the capability and effectiveness of the proposed method. Experimental results show that the proposed method outperforms other related methods in diagnosing critical faults in FOWTs under various operating conditions.

Utilization of desilication products as efficient adsorbents for the removal of basic fuchsine

Desilication products (DSPs) are one of the main components of bauxite residue, which is currently discharged without further usage. The present study reports on the use of DSPs as adsorbents for basic fuchsine dye. Using artificial spent liquor, we synthesized not only neat DSP but also solids in the presence of various organics, to account for their likely occurrence during the Bayer process. The physico-chemical properties of all DSPs are similar, except for the specific surface area (SSA), which decreases as the organic content in the final product increases. Further, we compared the adsorption characteristics of DSP to those of Y-type faujasite (FAUY). Strikingly, both time-dependent adsorption measurements and adsorption isotherms showed that DSP, despite its 28-fold smaller SSA, binds 4–5 times more dye molecules. Computational modelling for sodalite (as a model for DSP) and FAUY indicates not only more favourable adsorbent-adsorbate interactions, but also more available free Si-OH sites for binding of fuchsine in the case of sodalite. Finally, we find that organic impurities present in the Bayer liquor do not alter the adsorption capacity of neat DSP to any significant degree; therefore, this adsorbent tolerates numerous organic contaminants without decreasing its affinity to the binding of fuchsine.

Nonuniversal Dynamics of Hyperbranched Metallo-Supramolecular Polymer Networks by the Spontaneous Formation of Nanoparticles.

Various transient and permanent bonds are commonly combined in increasingly complex hierarchical structures to achieve biomimetic functions, along with high mechanical properties. However, there is a traditional trade-off between mechanical strength and biological functions like self-healing. To fill this gap, we develop a metallo-supramolecular polymer hydrogel based on the hyperbranched poly(ethylene imine) (PEI) backbone and phenanthroline ligands, which have unexpectedly high plateau modulus at low concentrations. Rheological measurements demonstrate nonuniversal metal-ion-specific dynamics, with significantly larger plateau moduli, longer relaxation times, and stronger temperature dependencies, compared to equivalent networks based on model-type telechelic precursors, which cannot be explained by the theory of linear viscoelasticity. TEM images reveal the in situ mineralization of metal ions, which nucleate by the ligand complexation and grow thanks to the spontaneous reducing effect of the PEI backbone. Evidently, the complex lifetime works against Ostwald ripening, resulting in the formation of thermodynamically stable smaller particles. This trend is followed by time-dependent network buildup measurements and is confirmed by a kinetic model for particle formation and aggregation. The spontaneous formation of particles with complex lifetime-dependent sizes can explain the nonuniversal dynamics through the interaction of polymer segments and particles at the nanoscale. This work describes how the polymer backbone can affect the strength and stability of supramolecular bonds, promising for combining high mechanical properties and self-healing comparable to natural tissues.

Smoking and alcoholism dual addiction dissemination model analysis with optimal control theory and cost-effectiveness.

A mathematical model of the dual addiction dissemination dynamics of alcoholism and smoking was created and examined in this work, along with cost-effectiveness and optimal control techniques. The primary goal of the research is to determine which cost-efficient management techniques are most helpful in lowering the problem of dual addiction dispersion in the community. The smoking addiction sub-model, the alcohol addiction sub-model, and the dual addiction model between alcohol and smoking were all calculated, and their stability was examined in this study. The effective reproduction numbers of the models are computed using the next-generation operator technique. When the model's effective reproduction number is smaller than one, the backward bifurcation phenomenon is seen. Six time-dependent control measures are taken into consideration when formulating and analyzing the optimum control issue. Utilizing and applying the parameter values and using MATLAB ode45 solver we performed numerical simulations for both the dual addiction model and its optimal control problem. Furthermore, using the incremental cost-effectiveness ratio (ICER), we carried out the cost-effectiveness analyses. The cost-effectiveness analysis shows that implementing all the protection (education) control measures simultaneously (i.e., implementing Strategy A) is the most cost-effective strategy. Finally, we recommend that the public health stakeholders must put great effort into the implementation of Strategy A to reduce the smoking and alcoholism dual addiction dissemination problem in the community.

Synergistic corrosion inhibition of 4-hydroxypyridine and halogen ions: Insights from interfacial nonlinear spectroscopy.

4-Hydroxypiridine (4-HPy) is a green chemistry corrosion inhibitor for low-carbon steel, valued for its environmental compatibility and low toxicity. Despite lower initial effectiveness than 4-mercapto/4-aminopyridine, 4-HPy's performance is markedly enhanced by halogen ions. By employing second harmonic generation (SHG) spectroscopy combined with electrochemical methods, Raman spectroscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and in situ UV spectroscopy, this study elucidates the synergistic enhancement mechanism of 4-HPy with Cl-, Br-, and I- in 0.5 mol/L HCl solution. Time-dependent SHG measurements showed a two-step process of rapid adsorption and subsequent orientation change, with a proposed mechanism to interpret the temporal changes in SHG intensity. Deducing the adsorption kinetic equations and their application to the experimental data yields the adsorption rate (kad) and orientation change rate (Kre). Halogens reduce the orientation angle of 4-HPy, facilitating its adsorption on the substrate surface and effectively inhibiting corrosion via distinct mechanisms. Cl- and Br- ions primarily adsorb onto the metal surface, forming an adsorption film that not only enhances the subsequent adsorption of 4-HPy but also provides a protective effect for the metal surface. Conversely, I- forms mainly complexes with 4-HPy in solution, co-adsorbs onto the metal surface, and demonstrates a significant synergistic effect. This study revealed the synergistic efficacy hierarchy among halogen ions, with the order 4HPy + NaCl < 4HPy + NaBr < 4HPy + NaI. This study enhances our molecular-level understanding of the synergistic mechanism between halogen ions and corrosion inhibitors and provides valuable insights for designing and developing effective corrosion inhibitors.

Experimental investigation of equilibrium and temporal scour around the round head of the rubble mound breakwater in case of breaking and non-breaking waves

In this study, local sediment movements caused by regular wave effects around the head section of rubble mound breakwater were investigated experimentally. The experiments were performed in a wave channel with a length of 33 m, a width of 3.6 m and a depth of 1.2 m. A plunger-type wave generator was located at the offshore side, generating regular waves of varying heights and periods. Uniform sandbed material of three different grain sizes was used, alongside two distinct breakwater slopes and six different wave characteristics. Experiments were performed under both breaking and non-breaking wave conditions. Time-dependent scour depth and water level measurements were determined by using measuring equipment working with an ultrasonic method. In the paper, new empirical relations were derived for temporal relative scour depths and the non-dimensional time scale parameter and the non-dimensional time scale parameter. The determination coefficient and scatter index of these derived relations were calculated and evaluated statistically. It was observed that the relations are in good agreement with those obtained from experiments. Additionally, the findings indicate that wave breaking significantly reduces the equilibrium scour depth.

A comparison of machine learning methods for recovering noisy and missing 4D flow MRI data.

Experimental blood flow measurement techniques are invaluable for a better understanding of cardiovascular disease formation, progression, and treatment. One of the emerging methods is time-resolved three-dimensional phase-contrast magnetic resonance imaging (4D flow MRI), which enables noninvasive time-dependent velocity measurements within large vessels. However, several limitations hinder the usability of 4D flow MRI and other experimental methods for quantitative hemodynamics analysis. These mainly include measurement noise, corrupt or missing data, low spatiotemporal resolution, and other artifacts. Traditional filtering is routinely applied for denoising experimental blood flow data without any detailed discussion on why it is preferred over other methods. In this study, filtering is compared to different singular value decomposition (SVD)-based machine learning and autoencoder-type deep learning methods for denoising and filling in missing data (imputation). An artificially corrupted and voxelized computational fluid dynamics (CFD) simulation as well as in vitro 4D flow MRI data are used to test the methods. SVD-based algorithms achieve excellent results for the idealized case but severely struggle when applied to in vitro data. The autoencoders are shown to be versatile and applicable to all investigated cases. For denoising, the in vitro 4D flow MRI data, the denoising autoencoder (DAE), and the Noise2Noise (N2N) autoencoder produced better reconstructions than filtering both qualitatively and quantitatively. Deep learning methods such as N2N can result in noise-free velocity fields even though they did not use clean data during training. This work presents one of the first comprehensive assessments and comparisons of various classical and modern machine-learning methods for enhancing corrupt cardiovascular flow data in diseased arteries for both synthetic and experimental test cases.

Ligand-assisted reprecipitation synthesis of highly luminescent and stable CsPbBr3@SiO2 nanoparticles with formation kinetics analysis

Cesium lead bromide (CsPbBr3) perovskite nanocrystals are becoming a popular alternative to chalcogenide quantum dots because of their bright green fluorescence and high color purity. However, owing to the poor stability caused by their highly ionic nature and the dynamic binding of long-chain capping ligands, their practical applications are limited. Although (3-aminopropyl)triethoxysilane (APTES) is a frequently used insulating material for wrapping CsPbBr3nanocrystals, it often causes surface etching. To address this issue, we introduced oleic acid into the anti-solvent toluene to inhibit the etching effect of APTES using a modified room-temperature ligand-assisted reprecipitation process. We utilized in situ time-dependent photoluminescence measurements to study the formation kinetics of CsPbBr3nanocrystals and determine the optimal ligands ratio. This innovative approach enables precise control over CsPbBr3@SiO2nanoparticles synthesis, yielding uniformly shaped nanocrystals with a silica shell, a consistent size around 10.17 ± 1.6 nm, and enhanced photoluminescence quantum yields ranging from 90% and 100%. The photoluminescence lifetimes of our CsPbBr3@SiO2nanoparticles were significantly prolonged owing to a reduction in non-radiative recombination. This boosts their stability in thermal and polar solvent environments, making them superior candidates for use in photonic devices.

A nonparametric point-by-point method to measure time-dependent frequency in wavelength modulation spectroscopy

A nonparametric point-by-point (NPP) method is presented for high-accuracy measurement of the time-dependent frequency (laser frequency) in tunable laser absorption spectroscopy, crucial for ensuring ultimate measurement accuracy. In wavelength modulation spectroscopy in particular, the parametric methods in current use for time-dependent frequency measurement are insufficiently accurate and are difficult to apply to complex modulation scenarios. Based on a multi-scale viewpoint, point-by-point measurement of the frequency is realized by linear superposition of the frequency information mapped from the interferometric signal on a unit scale and on a local scale. Validation experiments indicate that the measurement accuracy of the proposed NPP method is three times that of the existing parametric methods, while effectively immunizing against non-ideal tuning effects. Additionally, the NPP method is suitable for use with arbitrarily complex modulations such as square wave modulation, for which parametric methods are inapplicable.

Design of blue-emitting adenosine monophosphate-copper nanocluster: Detection of Vitamin B2 in real samples

We demonstrate a simple preparation protocol for the synthesis of novel adenosine monophosphate-stabilized copper nanoclusters (AMP-Cu NCs). Synthesis parameters are optimized to reach the best fluorometric signal. The prepared Cu NCs show characteristic blue emission at 430 nm, which is related to the presence of Cu13 metal cores. Three distinct lifetime components are identified and the metallic feature of the NCs is proven by X-ray photoelectron spectroscopy. The stability and the long-term storage of the AMP-Cu NCs were investigated by pH- and time-dependent measurements. Besides the synthesis and characterization, a possible liquid fluorescent assay method is also developed for the detection of the biologically important Vitamin B2 in complex real samples by with 2.01 ± 0.31 μM detection limit. For the real samples, the yeast and dietary supplements were selected, where the detected concentration of Riboflavin was in good agreement with the expected amount in these complex chemical systems.

Emergence of the reproduction matrix in epidemic forecasting.

During the recent COVID-19 pandemic, the instantaneous reproduction number, R(t), has surged as a widely used measure to target public health interventions aiming at curbing the infection rate. In analogy with the basic reproduction number that arises from the linear stability analysis, R(t) is typically interpreted as a threshold parameter that separates exponential growth (R(t) > 1) from exponential decay (R(t) < 1). In real epidemics, however, the finite number of susceptibles, the stratification of the population (e.g. by age or vaccination state), and heterogeneous mixing lead to more complex epidemic courses. In the context of the multidimensional renewal equation, we generalize the scalar R(t) to a reproduction matrix, [Formula: see text], which details the epidemic state of the stratified population, and offers a concise epidemic forecasting scheme. First, the reproduction matrix is computed from the available incidence data (subject to some a priori assumptions), then it is projected into the future by a transfer functional to predict the epidemic course. We demonstrate that this simple scheme allows realistic and accurate epidemic trajectories both in synthetic test cases and with reported incidence data from the COVID-19 pandemic. Accounting for the full heterogeneity and nonlinearity of the infection process, the reproduction matrix improves the prediction of the infection peak. In contrast, the scalar reproduction number overestimates the possibility of sustaining the initial infection rate and leads to an overshoot in the incidence peak. Besides its simplicity, the devised forecasting scheme offers rich flexibility to be generalized to time-dependent mitigation measures, contact rate, infectivity and vaccine protection.

High-performance transparent AZO UV photodetectors

In this work, the fabrication of undoped ZnO (ZO) and 3 at.% aluminum (Al) doped ZnO (AZO) thin films (TFs) based transparent photodetectors (PDs) was reported. Both films were spin-coated on fluorine-doped tin oxide (FTO) substrates to investigate the influence of Al doping on the ultraviolet (UV) detection performance of the devices. The systematic characterizations reveal that Al doping positively affects the characteristics of ZO-TFs. The Al doping leads to slight shift in crystalline peaks and induces an enhancement in grain size. In addition, the surface roughness of ZO-TFs gets lower on Al doping. Further, the Al doping improved the transparency and widening of band gap of TFs. The PDs having metal–semiconductor-metal (MSM) configuration were achieved by screen-printing of Ag paste onto ZO and AZO-TFs. The current–voltage (I-V) profiles of the fabricated PDs were measured in the dark and under UV excitation of 365 nm. The AZO-TFs based MSM PD exhibits a spectral responsivity of 326.82 mA/W and an external quantum efficiency of 111.03%. The reproducibility of the fabricated PDs was tested by performing time-dependent photo-response measurements.

Vibrational energy relaxation in shock-heated CO/N2/Ar mixtures.

Experimental and numerical studies were performed on the vibrational energy relaxation in shock-heated CO/N2/Ar mixtures. A laser absorption technique was applied to the time-dependent rovibrational temperature time-history measurements. The vibrational relaxation data of reflected-shock-heated CO were summarized at 1720-3230K. In shock-tube experiments, the rotational temperature of CO quickly reached equilibrium, whereas a relaxation process was found in the time-dependent vibrational temperature. For the mixture with 1.0% CO and 10.0% N2, the vibrational excitation caused a decrease in the macroscopic thermodynamic temperature of the test gas. In the simulations, the state-to-state (StS) approach was employed, where the vibrational energy levels of CO and N2 are treated as pseudo-species. The vibrational state-specific inelastic rate coefficients of N2-Ar collisions were calculated using the mixed quantum-classical method based on a newly developed three-dimensional potential energy surface. The StS predictions agreed well with the measurements, whereas deviations were found between the Schwartz-Slawsky-Herzfeld formula predictions and the measurements. The Millikan-White vibrational relaxation data of the N2-Ar system were found to have the most significant impact on the model predictions via sensitivity analysis. The vibrational relaxation data of the N2-Ar system were then modified according to the experimental data and StS results, providing an indirect way to optimize the vibrational relaxation data of a specific system. Moreover, the vibrational distribution functions of CO and N2 and the effects of the vibration-vibration-translation energy transfer path on the thermal nonequilibrium behaviors were highlighted.

Optimal Control and Cost Effectiveness Analysis for the Transmission Dynamics of Yaws Infection

This work considered a neglected bacterial disease for which non-linear model of yaws infection with time dependent control measures was developed to study the effect of the control measures in tackling the disease transmission in the population. Optimal control strategy was developed in order to investigate and analyze the optimal cost for controlling the transmission of the diseases in the population. Pontryagin’s Maximum Principles (PMP) was applied to carry out economic evaluations in order to optimize the cost of the intervention in the models and also to optimize the objective functional so as to establish the most optimal control strategy in tackling the spread of the infections. Numerical simulations had been carried-out for the model using forward-backward Runge-Kutta of order four to study the effect of the control strategies and also to calculate the incremental cost effectiveness ratios (ICERs) for the implementation of various combinations of the control parameters for the yaws infection in order to determine the most cost effective strategy that could check the spread of the disease. The findings showed that the most cost-effective strategy to check the spread of yaws infection is the combination of personal hygiene and treatment for infection as a single control strategy

Uniqueness and numerical inversion in bioluminescence tomography with time-dependent boundary measurement

In the paper, an inverse source problem in bioluminescence tomography (BLT) is investigated. BLT is a method of light imaging and offers many advantages such as sensitivity, cost-effectiveness, high signal-to-noise ratio and non-destructivity. It thus has promising prospects for many applications such as cancer diagnosis, drug discovery and development as well as gene therapies. In the literature, BLT is extensively studied based on the (stationary) diffusion approximation (DA) equation, where the distribution of peak sources is reconstructed and no solution uniqueness is guaranteed without proper a priori information. In this work, motivated by solution uniqueness, a novel dynamic coupled DA model is proposed. Theoretical analysis including the well-posedness of the forward problem and the solution uniqueness of the inverse problem are given. Based on the new model, iterative inversion algorithms under the framework of regularizing schemes are introduced and applied to reconstruct the smooth and non-smooth sources. We discretize the regularization functional with the finite element method and give the convergence rate of numerical solutions. Several numerical examples are implemented to validate the effectiveness of the new model and the proposed algorithms.