Solution Method Research Articles

Electrochemical Detection of Nitrite on PANI-TiO2/Pt Nanocomposite-Modified Carbon Paste Electrodes Using TOPSIS and Taguchi Methods.

Platinum nanoparticles are widely used in electrocatalysis and sensors. In this work, a novel modified carbon paste electrode based on PANI-TiO2/Pt nanocomposites was developed electrochemically. To improve the performance of the PANI-TiO2/Pt composite-modified electrode, a Taguchi orthogonal array was used for experimental design, and the best values of factors affecting the performance were determined using the technique for order preference by similarity to ideal solution (TOPSIS) and Taguchi optimization methods. The electrochemical catalytic activities of the PANI-TiO2/Pt composite-modified electrode on the oxidation of nitrite was calculated by electrochemical analysis. The experimental results demonstrate that the PANI-TiO2/Pt electrode has pretty excellent electrocatalytic ability for the oxidation of nitrite. The sensing performances of the proposed electrode were evaluated, including linear detection range, sensitivity, LOD, selectivity, and stability for nitrite sensing.

Landslide detection based on deep learning and remote sensing imagery: A case study in Linzhi City

Landslides result in serious damage to economic and land resources. Automated landslide detection over a wide area for the study and prevention of geohazards is important. Linzhi is located in the southeastern part of the Tibetan Plateau, one of the most landslide-prone regions in China. In this paper, we utilize a deep learning approach in combination with remote sensing images to detect landslides in Linzhi City. SHAP-based interpretability analysis and exponential Weighted Method and Technique for Order Preference by Similarity to Ideal Solution (EWM-TOPSIS) method are employed to investigate the catastrophic factors that affect landslides and results of landslide detection in Linzhi City. The obtained results indicate that the model is basically accurate in landslide detection in the Linzhi area, and most of the evaluation indexes of the model training are above 80%. Moreover, vegetation cover and rainfall are important causal factors triggering landslides in Linzhi City. Our research will provide a reference for landslide detection in similar areas.

Transparent boundary condition and its effectively local approximation for the Schrödinger equation on a rectangular computational domain

The transparent boundary condition for the free Schrödinger equation on a rectangular computational domain requires implementation of an operator of the form ∂t−i△Γ where △Γ is the Laplace-Beltrami operator. It is known that this operator is nonlocal in time as well as space which poses a significant challenge in developing an efficient numerical method of solution. The computational complexity of the existing methods scale with the number of time-steps which can be attributed to the nonlocal nature of the boundary operator. In this work, we report an effectively local approximation for the boundary operator such that the resulting complexity remains independent of number of time-steps. At the heart of this algorithm is a Padé approximant based rational approximation of certain fractional operators that handles corners of the domain adequately. For the spatial discretization, we use a Legendre-Galerkin spectral method with a new boundary adapted basis which ensures that the resulting linear system is banded. A compatible boundary-lifting procedure is also presented which accommodates the segments as well as the corners on the boundary. The proposed novel scheme can be implemented within the framework of any one-step time marching schemes. In particular, we demonstrate these ideas for two one-step methods, namely, the backward-differentiation formula of order 1 (BDF1) and the trapezoidal rule (TR). For the sake of comparison, we also present a convolution quadrature based scheme conforming to the one-step methods which is computationally expensive but serves as a golden standard. Finally, several numerical tests are presented to demonstrate the effectiveness of our novel method as well as to verify the order of convergence empirically.

A method for calculating two-phase equilibrium: Constrained gray prediction evolutionary algorithm with a surrogate model based on quadratic interpolation

Traditional methods, including direct solution methods based on Newton's method and indirect solution methods based on thermodynamic principles, are the mainstream methods used to solve the volume-temperature flash calculation (called NVT-flash), even though they suffer from drawbacks such as sensitivity to initial value and complexity of derivative calculations. A constrained backtracking search algorithm (CBSA), proposed in 2024, was the first and only metaheuristic algorithm to successfully tackle the NVT-flash problem, which overcomes shortcomings of traditional methods. Considering the advantages of metaheuristic algorithms, a constrained gray prediction evolutionary algorithm with a surrogate model based on quadratic interpolation (CGPE-QI) is proposed in this paper to deal with the NVT-flash problem. CGPE-QI considers total Helmholtz free energy as the objective function, moles vector, and volume of a single phase as variables. Constraints to solve the NVT-flash problem are addressed by using a direct search method and an exterior point method. Numerical experiments on two-phase equilibrium of pure substance and mixtures are carried out employing CGPE-QI. Experimental results are the same as those obtained by traditional methods, which confirms that CGPE-QI can effectively tackle the NVT-flash problem and possesses energy decay property. In particular, the results demonstrate that CGPE-QI is more competitive than CBSA in terms of convergence speed, stability, and calculation cost. CGPE-QI proposed in this paper is the second metaheuristic algorithm to successfully solve the NVT-flash problem, illustrating that metaheuristic algorithms have great potential in solving phase equilibrium calculation problems.

Assessing hydropower capability for accommodating variable renewable energy considering peak shaving of multiple power grids

Hydropower can play a transformative role in supporting the substantial increase in variable renewable energy (VRE) via flexible regulation ability, but the capability of cascade hydropower to buffer VRE is indistinct. This study proposes a systematic framework to assess hydropower capability for integrating VRE considering the peak shaving demands of multiple power grids. A chance-constrained multi-time aggregate model for the integrated hydro-wind-solar operation is established to determine the optimal wind and solar capacity and coordinated operational strategies. An independent hydropower peak shaving operation model is proposed for comparison. The proposed models are recast as mixed integer linear programming formulations based on the proposed solution method. Comparative situation experiments divided by different influencing factors are implemented to analyze hydropower capability for integrating VRE. The results revealed the following: (1) Integrating VRE would reduce the peak shaving effectiveness of hydropower—the lowest load rate decreases to 0.899. (2) Hydropower capability for integrating wind and solar power is affected by hydrological conditions. Hydropower capability is limited under fixed hydrological conditions, and it prioritizes expanding wind power and restricting solar power. (3) Expanding the transmission capacity will increase hydropower capability from 13300 to 17000 MW and enhance peak shaving performance through the increased hydropower contribution.

Physical mechanism-driven extraction model for post-seismic deformation recorded by continuous GNSS observations

Post-seismic deformation caused by large earthquakes is one of the most effective parameters for investigating the frictional behavior of faults and the rheological characteristics of the lithosphere. This study introduces a modified functional model that accounts for both afterslip and viscoelastic relaxation effects, incorporates a physical mechanism, and effectively disentangles distinct mechanisms of post-seismic deformation captured by continuous GNSS observations.A parameter optimization solution method based on the Bayesian framework was adopted to obtain optimal estimates and corresponding confidence intervals. The effectiveness of proposed model was validated through simulation experiments. The proposed method was applied to study post-seismic deformations from the 2015 Nepal MW 7.8 earthquake, and the different characteristics of post-seismic deformations caused by different mechanisms were discovered at different stations. The afterslip effect has the duration of 2.67 years, whereas the viscoelastic relaxation effect will continue for 150.8 years. Moreover, the calculated equivalent viscosity coefficient in the southern Tibet region was 1.1 ± 0.3 × 1018 Pa·s. Our proposed model can more accurately and objectively separate different mechanisms from the post-seismic displacements observed by GNSS than previous one, and thus improve the accuracy of fault kinematics and regional lithosphere rheology investigations.

Lead-free Ce-doped perovskite scintillators with high figure of merit

Lead halide perovskite scintillators have recently received extensive research attention owing to their short fluorescence lifetimes, low detection limits, and ease of fabrication compared to traditional scintillators. The nontoxic cerium-doped lead-free perovskites with intrinsically efficient and short lifetime d–f transitions are a prospective replacement for the toxic Pb2+. Here, we demonstrated Ce-doped cesium lanthanide chloride perovskites (Cs3LnCl6, Ln=Gd, Y, Lu) synthesized through a facile solution method for the first time. These perovskites exhibit blue-violet emission, which arises from Ce 5d→4f transitions. Among three types of Cs3LnCl6 perovskites, Ce:Cs3LuCl6 exhibited high photoluminescence quantum yield (PLQY) of 82% and a short excited-state lifetime of approximately 34 ns. When utilized as X-ray scintillators, Ce:Cs3LuCl6 crystals display a high light yield of 8120 photons per MeV and a low detection limit of 36.8 nGy air s−1. Importantly, the figure of merit (FoM), representing the ratio of light yield to decay time, reaches 239, which is the highest reported value for lead-free perovskite scintillators up to now. Additionally, the fabrication of perovskite/PMMA films was undertaken for practical demonstrations in X-ray imaging, resulting in the attainment of a resolution of up to 8.38 lp/mm. We anticipate that this work will inspire the utilization of Ce-doped Cs3LnCl6 perovskites in ultrafast scintillation applications such as high-energy physics, nuclear reaction monitoring, and dynamic X-ray imaging.

Ultralight reduced graphene oxide based foam with excellent electromagnetic interference shielding and superior mechanical properties

Reduced graphene oxide/carboxymethyl cellulose (RGO/CMC) foams with ultra-lightweight, excellent EMI shielding and mechanical robustness are fabricated based on a facile solution method and regulation of thermal reduction conditions. Results indicate that the two-step heating mode is good to obtain better EMI shielding properties. By introducing only 10 wt% of CMC, high electrical conductivity up to 34.7 S/m and EMI shieling effectiveness (SE) up to 34.6 dB are obtained. In addition, due to the connection effect of CMC, superior compressive strength and modulus as high as 8.3 KPa and 29.2 KPa are achieved, corresponding to an increase of 388.2% and 378.7%, respectively, compared to that of the RGO foam without CMC. Moreover, due to the ultralow density (∼4.1 mg/cm3) and high EMI SE of RGO/CMC, excellent specific shielding efficiency as high as 42195 dB.cm2/g is obtained, way much superior to that of other metal-, graphene-, and CNT-based carbon foams. This work will have great significance for facile fabricating efficient EMI shielding materials towards electronics and aerospace applications.

A systematic problem analysis network for product conceptual design

Problem analysis is a starting point of product development. The effective problem analysis can narrow the scope of potential problems and improve design efficiency. Although different methods have been proposed for the design problem analysis, the existing tools of the problem analysis are not systematic and effective. This paper presents a product design problem analysis and solution method based on problem networks. The proposed method conducts the problem decomposition, derivation and solving by considering the problem generation, exploratory and hypotheticals. Computer-aided analysis tools are integrated to improve reproducibility of the analysis solution and reduce the workload of designers. The method is applied in developing a new type of the charging gun cable with a granted patent. Feasibility and effectiveness of the proposed method are proved.

Study of the effects of heating on the physical, optical, and electrical properties of NiO thin films synthesized using a low-cost sol-gel method

Developments in low-cost techniques for growing high-quality nickel oxide thin films (NiOTFs) are critical enablers for the fabrication of NiO-based devices, particularly solar cells, light-emitting diodes, lasers, and many other applications. In this study, it has been demonstrated that the optical, electrical, and structural characteristics of NiOTFs coated on glass substrate employing a low-cost solution method are strongly influenced by post-thermal annealing treatments in ambient air. A comprehensive study was carried out on the characteristics of the deposited NiOTFs. X-ray diffraction (XRD) measurements indicate the enhancement of the crystal quality of films after annealing. There is a noticeable change and improvement in coated NiOTFs with heat treatment at 300 and 600 ℃ due to clear shifts in density. During the heating temperature increment, the energy of the band gap was shifted from 3.63 to 3.44 eV, and the electrical resistance of the NiOTFs varied from 1020 to 700 Ω-cm. Furthermore, the results indicate that the low-cost sol-gel (SG) deposition technique has a greater potential for producing high-quality p-type NiOTFs with minimal defects for electronic device applications.

A constrained differential evolution algorithm for calculation of two-phase equilibria at given volume, temperature and moles

A variety of strategies including two types of direct solution methods based on Newton's method and indirect solution methods based on thermodynamic principles have been developed, which can find satisfactory solutions for the phase equilibrium calculation problem at given volume, temperature and moles (NVT-flash). However, these methods are sensitive to the initial values and depend on the objective function's derivative during calculation. To resolve these deficiencies, a constrained differential evolution algorithm (abbreviated as CDE) for calculating two-phase equilibria at given volume, temperature, and moles is presented in this paper. The total Helmholtz free energy is regarded as the objective function, and the moles vector and volume of a certain phase are taken as the decision variables. This paper deals with the constraints of the NVT-flash problem by using direct search method and exterior point method. The results of the investigations on pure substance, binary and ternary mixtures are in agreement with the published data, which proves the effectiveness in solving the NVT-flash problem and the energy attenuation characteristic of the algorithm. The proposed algorithm represents the first successful attempt to apply the meta-heuristic optimization algorithm to solve the phase equilibrium computation under NVT-flash, and it shows the promising application prospect of meta-heuristic optimization algorithms for solving the phase equilibrium calculation problems.

A 1+ Mechanism Model for Predicting the Mixed-Oil Concentration in Multiproduct Pipelines

Summary Petroleum products are frequently transported successively through the same multiproduct pipeline. Due to turbulent and convective diffusion mass transfer, two adjacent oils will mix with each other, forming a mixed-oil segment. Accurate and rapid prediction of mixed-oil concentration is crucial for the precise management of mixed-oil segments. Conventional 1D modeling methods exhibit shortcomings in accurately representing the asymmetric distribution characteristics of mixed-oil concentration curves, and high-dimensional models are not practically applied due to their prohibitive computational time costs. Building on the 1D model framework, this paper proposes a “1+” mechanism model by considering the convective mass transfer behavior between the turbulent core region and the laminar boundary layer, and new governing equations and corresponding numerical solution methods are also introduced. Simulation experiments affirm the ability of the new model to characterize the asymmetric distribution features of mixed-oil concentration curves, along with its high computational efficiency in engineering applications. This is demonstrated by the computational time of approximately 30 seconds for simulating a pipeline of 300 km in length (Δx = 10 m, Δt = 1 second, CPU: i5-12500H, RAM: 16 GB). When applied to pipelines in industrial scenarios, the new model is shown to accurately predict the distribution of mixed-oil concentration curves. The research findings are significantly beneficial in assisting field personnel to gain advanced insights into the mixed-oil concentration distribution at the station, enabling timely and well-informed strategies for handling mixed-oil segment, thereby enhancing the operational efficiency of multiproduct pipelines.

Talfīq as A Method for Legal Solutions in Contemporary Islamic Law

Talfīq, or the combination of various opinions of jurisprudence madhhab, is frequently used to arrive at solutions in Islamic law. It was used extensively in the tajdīd era, the early 20th century AD, namely through the Islamic law reforms in family and personal matters in most Muslim countries. The concept is controversial and not universally accepted by ulama. Most classical ulama opposed it, although most contemporary ulama believe that talfīq is acceptable as a method for legal solutions. This research investigated the reasons or factors for this disagreement by analyzing the related views of such ulama. The qualitative research used a literature review from classical and contemporary books about talfīq. This research concluded that although the classical ulama appeared to be grounded firmly in their opposition to the practice of talfīq, subsequent development of Islamic law showed practical consideration made inroads in accepting talfīq as a method for legal solution. This acceptance is made by putting conditions and controls on how and when talfīq can be used to solve modern Muslim legal problems. This modification ensures the traditionalists that the danger of talfīq, as previously envisaged, would be avoided. Abstrak: Talfīq atau gabungan berbagai pendapat mazhab fikih merupakan metode yang sering digunakan untuk mencari solusi dalam hukum Islam. Hal ini digunakan secara luas pada zaman tajdīd, yaitu awal abad XX Masehi, melalui reformasi hukum Islam dalam masalah hukum privat dan keluarga di sebagian besar negara Muslim. Konsepnya kontroversial dan tidak disetujui secara universal oleh para sarjana. Mayoritas ulama Islam klasik telah menentangnya meskipun sebagian besar ulama kontemporer berpandangan bahwa talfīq dapat diterima sebagai metode penyelesaian hukum. Penelitian ini bertujuan untuk menyelidiki alasan atau faktor ketidaksepakatan ini dengan melihat sampel dari pandangan terkait dari para ulama tersebut. Penelitian ini merupakan penelitian kualitatif dengan menggunakan tinjauan pustaka. Data diperoleh dari buku-buku klasik dan kontemporer yang menulis tentang talfīq. Penelitian ini menyimpulkan bahwa meskipun para ulama klasik pada mulanya tampak berpijak kuat pada penentangan mereka terhadap praktik talfīq, perkembangan hukum Islam selanjutnya menunjukkan pertimbangan praktis yang membuat terobosan dalam menerima talfīq sebagai metode penyelesaian hukum. Penerimaan ini dilakukan dengan meletakkan kondisi dan kontrol tentang bagaimana dan kapan talfīq dapat digunakan dalam memberikan solusi atas masalah hukum Islam modern. Modifikasi ini memastikan kaum tradisionalis menghindari bahaya talfīq seperti yang dibayangkan sebelumnya.

Existence of positive solutions for an elliptic system with sign-changing weights

Using the method of sub-super solutions and comparison principle, we study the existence of positive solutions for a class of quasilinear elliptic systems with sign-changing weights.

Decision-Making for The Selection of Vegetable Suppliers for Foods Distributors uses AHP and TOPSIS

The evaluation of supplier selection is an important aspect that needs to be considered in supply chain management. The best suppliers contribute to a more efficient supply chain system. Companies operating in the food distribution sector are particularly attentive to their suppliers. One of the products that receives significant attention is spinach, a perishable item, making supplier evaluation crucial. This research aims to evaluate the supplier selection of spinach products based on several criteria, such as delivery, quality, price, service, and location. Weighting is done using the Analytical Hierarchy Process (AHP). In this case, assessment or weighting is carried out by distributing questionnaires to three respondents in the field. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method is employed to determine the rankings of each alternative. The results of this study indicate that the price criterion has the highest weight with a weight of 0.39. The recommended selected alternative is alternative 4, with the highest average value (Vi) based on the assessments of three experts. This model proves capable of addressing the issues of supplier selection evaluation, leading to the selection of alternative or supplier 4 as the spinach supplier for the food distribution company.

Fifth-order A(α)-stable block hybrid adams-moulton method for solutions of predator-prey and Lorenz Systems

Problems associated with nonlinearity in predator-prey and chaotic nature embedded in Lorenz system place a significant challenge on numerical methods for their solutions. Some numerical methods may become unstable as step size increases. In this study, a fifth-order A(alpha )-stable (alpha = 89.90 ) k-step block hybrid Adams-Moulton method (BHAMM) was derived incorporating 16/9 as an off-step interpolation point using multistep collocation and matrix inversion technique. Choice of the off-step point of the BHAMM was in the upper part of interval of interpolation points. It was shown that the derived block method was consistent and zero-stable hence a convergent block method. Numerical simulations of predator-prey and Lorenz systems with the newly derived k=3 BHAMM indicated that it was adequate and compared well with Matlab ode23s.

Анализ частотных характеристик токовых датчиков цифрового трансформатора тока и напряжения

Digital measuring current and voltage transformers (DCVT), which incorporate various current and voltage sensors are the key sources of information about processes at modern digital substations. Classic small-sized current transformers, Rogowski coils, magnetotransistor sensors, Hall effect sensors, fiber-optic Faraday effect sensors, as well as shunts can be used as current sensors in DCVTs. For redundancy purposes, current channels are performed in several copies and on different sensors. Sensors that are different in nature have their own set of advantages, which together makes it possible to obtain the effect of eliminating the shortcomings of specific sensors. For example, they may not have a saturation effect or transmit the direct current component quite accurately, which is a significant advantage over classic current transformers. At the mains frequency, the behavior of these sensors is predictable, but their behavior is not well studied at higher and lower frequencies. Thus, it is decided to study the frequency response and phase response of these sensors in a wide frequency range. To solve the problems within the framework of this study, physical experiment, analytical and empirical solution methods have been used. As a result of the study, the frequency response and phase response of current sensors of DCVT in a wide frequency range have been obtained. Analog filter has been designed to correct the signal of the magnetotransistor sensor. The results obtained coincide with theoretical data and can be considered when developing digital relay protection and automation algorithms.

Evaluation of natech criteria in organized industrial zones: An application for Kırıkkale province

Natural disasters are unexpected natural events that cause severe property loss and moral damage. Türkiye has been exposed to many disasters due to its location. One of the disasters experienced is the Kahramanmaraş earthquake that occurred on February 6th, 2023, in the recent past. Two consecutive earthquakes caused significant loss of life and property. In addition, some technological accidents happened because of the earthquake. The biggest of these was the fire in the Iskenderun marina. After the earthquake, the big fire that started with the fire of the containers on the quay could be brought under control after a long effort and time. Although it is often overshadowed by natural disasters, technological accidents triggered by natural disasters (Natech) accidents can cause severe damage. Especially Organized Industrial Zones (OIZ) are in areas with high Natech risk. This study determined 10 criteria that will cause Natech accidents for OIZs by literature review. The Pythagorean Fuzzy Analytical Hierarchy Process (PFAHP) method is used to weight the criteria. Then, a ranking is made using The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method among the five sectors operating in Kırıkkale OIZ and which may have Natech risk.

Pell Collocation Approach for the Nonlinear Pantograph Differential Equations

Pantograph equations, which we encounter in the branches of pure and applied mathematics such as electrodynamics, control systems and quantum mechanics, are essentially a particular form of the functional differential equations characterized with proportional delays. This study focuses on exploring the approximate solution to the Pantograph differential equation. Since there is no analytic solutions for this equation class, only the approximate solutions can be obtain. For this purpose, Pell Collocation Method which is one of the numerical solution methods is chosen. As the result of applying the method to the equation, an algebraic equation system has been gained and then the approximate solution has been found by using MATHEMATICA via the given initial conditions. The method is applied to the some test examples and then the results are presented by both graphically and by table. The error estimations show that the method works accurately and efficiently.

Strategi Dekarbonisasi Untuk Industri Pertambangan Batu Bara di Indonesia Menggunakan Metode TOPSIS

The coal mining industry is one of the largest contributors to Indonesia’s economy and greenhouse gas emissions at the same time. Indonesian coal mining companies will inevitably expand their business to meet the demand and targets. But Indonesia already set its ambition to become a net-zero country by 2060 or earlier. Without a robust decarbonization strategy at the company level, Indonesia will face difficulties meeting the net-zero target. This study proposes to use one of the Multi-Criteria Decision Analysis, Technique for Order of Preference by Similarity to Ideal, Solution method within the Political, Economic, Social, Technology, Environmental, and Legal criteria to assess five prioritized decarbonization strategies, which are renewable energy, equipment electrification, business shifting, process efficiency, carbon offset. The analysis will evaluate essential sub-criteria such as regulation compliance, investment, social acceptance, technological readiness, and emissions reduction. The data was acquired from a survey of coal mining stakeholders, other journal reviews, and company disclosures. The final results show that process efficiency scores highest on the selected criteria due to high economic and technological value. Meanwhile, other criteria like carbon offset, renewable energy use, and equipment electrification receive lower scores.