Exchange Operations Research Articles

Studies on rheological properties and isobaric heat capacity of ZnO - [C4mim][BF4] nanoparticle enhanced ionic liquid

Nanotechnology is evolving every year and contributes significantly to energy savings in many heat exchange operations. This article provides some experimental insights into the area of ionic liquids and nanoparticle enhanced ionic liquids, while the tests were performed with [C4mim][BF4] and ZnO nanoparticles in mass concentrations up to 2.5 %wt.. Data were collected at different temperatures and successive heating – cooling cycles were applied to check the properties hysteresis as well as the new fluids behavior as heat transfer agents. Results indicated a normal fluidic behavior, while the increase in viscosity is moderate, as well as the decrease in isobaric heat capacity. A special behavior was noticed for the sample with 2.5 %wt. ZnO, that has non Newtonian flow and the isobaric heat capacity was higher than that of the low concentration suspensions. Further, results were discussed in terms of phenomenon and current knowledge and few correlations were proposed. Concluding, even if this research is a step forward to nanoparticle enhanced liquids state of the art, there is still enough room for research in order to get a full understanding of these fluids comportment at heat transfer.

Специальные инструменты выявления и противодействия недобросовестным практикам с цифровыми финансовыми активами

Purpose: The article discusses conceptually new approaches to resist using cryptocurrencies and electronic payment means in unfair practices. As a result, it was found that all of them are aimed at revealing suspicious transactions and deanonymized individuals involved in illegal activities. The conclusion is substantiated that information and analytical systems constitute promising special tools for effective control of cryptocurrency market and blockchain networks. The research theoretical basis comprises scientific publications of the experts specialized in the issues of involvement, blockchain technology, distributed registries and cryptocurrencies at the investigation of crimes as well as foreign software tools, applied in the field of blockchain networks security. Methods: In the research, the author relies on deduction, generalization, synthesis and system analysis methods. Results: Determination of the capabilities of foreign and domestic software special tools in the field of virtual wallet providers and exchange operators (such as “crypto-currency brokers’ board”, etc.). Practical significance: The mechanism of functioning of special software tools for deanonymization of transactions in order to resist the use of cryptocurrencies and payment electronic means in unfair practices is presented.

Josephson junction scheme for observing the non-Abelian statistical properties of Majorana fermions

Since Majorana zero mode (MZM) was proposed applicable for topological quantum computing, the past two decades have witnessed a growth of theoretical and experimental advances. Here we propose a Josephson junction setup consisting of intrinsic topological superconductors, and show that with the exchange operation of two MZMs, the single-electron tunneling current will reverse sign as a result of its non-Abelian statistics, which can be further utilized to read out the initial qubit of the system. This work offers a way to demonstrate the non-Abelian statistical properties of MZMs.

A perturbation based modified BAT algorithm for priority based covering salesman problem

In this study, Bat algorithm (BA) is modified along with K-opt operation and one newly proposed perturbation approach to solve the well known covering salesman problem (CSP). Here, along with the restriction of the radial distances of the unvisited cities from the visited cities another restriction is imposed where a priority is given to some cities for the inclusion in the tour, i.e., some clusters to be created where the prioritised cities must be the visiting cities and the corresponding CSP is named as Prioritised CSP (PCSP). In the algorithm, 3-opt and 4-opt operations are used for two different purposes. The 4-opt operation is applied for generating an initial solution set of CSP for the BA and the 3-opt operation generates some perturbed solutions of a solution. A new perturbation approach is proposed for generating neighbour solutions of a potential solution where the exchange of some cities in the tour is made and is named as K-bit exchange operation. The proposed solution approach for the CSP and PCSP is named as the modified BA embedded with K-bit exchange and K-opt operation (MBAKEKO). It is a two-stage algorithm where in the first stage of the algorithm the clustering of the cities is done with respect to a fixed visiting city of each cluster in such a manner that the distances of the other cities of the cluster must lie with in the fixed covering distance of the problem and in the second stage the BA is applied to find the minimum cost Hamiltonian circuit by passing through the visiting cities of the clusters. MBAKEKO is tested with a set of benchmark test problems with significantly large sizes from the TSPLIB. To measure the performance of MBAKEKO, its results are compared with the results of different well-known approaches for CSPs available in the literature. It is observed from the comparison studies that MBAKEKO searches the minimum cost tour for any of the considered instances compared to all other well-known algorithms in the literature. It can be concluded from the numerical studies that the performance of MBAKEKO is better with respect to the state-of-the-art algorithms available in the literature.

An optimization framework for analyzing dual‐donor organ exchange

We study an optimal matching problem in the context of dual‐donor organ exchange, where a portion of two living donors' organs are transplanted to a single patient. This dual‐donor transplant technique is becoming more widespread for lung and liver transplants. However, multiple medical compatibility criteria pose a serious challenge for matching a patient with two compatible donors. In the United States and many other countries, laws prohibit commercial (for‐profit) deals for human organs, so donor exchanges are run by nonprofit organizations connecting donors with people in need of organs, with the goal of increasing transplant matches. We propose a simple chain mechanism in dual‐donor organ exchange to increase the number of patient–dual‐donor matches, which would maximize the number of patients receiving transplants. Based on this objective, we propose a general simple chain optimization framework for finding the maximum patient matching, taking into account multiple compatibility criteria (e.g., blood type and weight), and determine the complexity status of the problem. We provide theoretical results on the structures of simple chains, as well as a polynomial time algorithm to obtain the maximum patient matching simple chain with blood type compatibility. Through a numerical study for multiple compatibility criteria, we show that in many scenarios, a simple chain substantially increases the number of patients matched with dual donors for transplants, as opposed to exchange cycles. We also address the problem of maximizing the number of patients matched for dual‐donor organ transplants via two‐way and three‐way exchange cycles, subject to donors' and recipients' medical compatibility criteria, along with a discussion of their computational complexity. Finally, we characterize the general configurations of large n‐way exchange cycles and provide theoretical insights for their structural properties. Our findings provide general optimization models for dual‐donor organ exchange operators to increase the number of patients matched for transplant, given multiple compatibility criteria. In addition, we show how exchange operators, using simple chains, can increase patient matches and reduce simultaneous surgical resource requirements over exchange cycles.

Low-rank approximations to accelerate hybrid functional enabled real-time time-dependent density functional theory within plane waves

Real-time time-dependent density functional theory (RT-TDDFT) is a powerful tool for predicting excited-state dynamics. Herein, we combine the adaptively compressed exchange (ACE) operator with interpolative separable density fitting (ISDF) algorithm to accelerate the hybrid functional calculations in RT-TDDFT (hybrid RT-TDDFT) dynamics simulations for molecular and periodic systems within plane waves. Under this low-rank representation, we demonstrate that the ACE-ISDF enabled hybrid RT-TDDFT can yield accurate excited-state dynamics, but much faster than conventional calculations. Furthermore, we describe a massively parallel implementation of ACE-ISDF enabled hybrid RT-TDDFT dynamics simulations containing thousands of atoms (1728 atoms), which can scale up to 3456 central processing unit cores on modern supercomputers.

Means in money exchange operations

Journal of Applied Mathematics and Computational Mechanics, Prace Naukowe Instytutu Matematyki i Informatyki, Politechnika Częstochowska, Scientific Research of the Institute of Mathematics and Computer Science, Czestochowa University of Technology

Recovery by discretization corrected particle strength exchange (DC PSE) operators

A new recovery technique based on discretization corrected particle strength exchange (DC PSE) operators is developed in this paper. DC PSE is an established collocation method that can be used to compute derivatives directly at nodal points, instead of by projection from Gauss points as is done in many finite element-based recovery techniques. The proposed recovery technique is truly meshless and does not require patches of elements to be defined, which makes it generally applicable to point clouds and arbitrary element topologies. Numerical examples show that the proposed method is accurate and robust.

Selective Photocatalytic Conversion of Methane Induced by Lewis Acid–Base Pair on the Surface of In2O3/TiO2 Heterojunction Photocatalyst

The efficient catalytic conversion of light-driven methane (CH4) is still very challenging. Here, the surface-reconstructed In2O3/TiO2 heterojunction photocatalyst is successfully prepared by a two-step operation of ion exchange and calcination, and the efficient selective photocatalytic conversion of CH4 is achieved. In the absence of O2, the formation rates of ethane (C2H6) and hydrogen (H2) are 68.9 and 78.6 μmol h–1 g–1, respectively, which corresponds to the stoichiometric ratio. However, in the presence of O2 or water (H2O) as the oxidant, CH4 is converted to CO, and the CO formation rates are 113.2 and 94.4 μmol h–1 g–1, respectively. Our results show that the In3–O2– Lewis acid–base pair on the In2O3/TiO2 surface can realize the adsorption and activation of CH4. Moreover, the photogenerated hole-induced reactive oxygen centers (Ti4+O·–Ti4+OH– and Ti4+O2–Ti4+O·–) on the surface of In2O3/TiO2 are identified as the active species for inducing the dissociation of CH4 into ·CH3 radicals, which in turn are coupled into C2H6 by ·CH3. In contrast, in the presence of O2, the surface superoxide anion (O2–), surface ·O– radicals, and O22– anions are identified as the active species for inducing the oxidation of CH4 into CO.

Thermal hydraulic characteristics of liquid sodium and supercritical CO2 in a diffusion bonded heat exchanger

Compact heat exchangers are being examined for use in advanced, high-temperature nuclear or concentrated solar power plants to improve thermal efficiencies and reduce capital costs. At the time of this work, no experimental investigation of liquid sodium in the popular diffusion-bonded heat exchanger design had been performed. This paper describes the thermal-hydraulic and overall operations performance observed during testing of a 316/L stainless steel “zig-zag” microchannel heat exchanger operating between a (0.5 kg/s) sodium loop and a (0.3 kg/s) recuperated supercritical CO2 system with outlet conditions up to 550 °C at 16 MPa. Observed pressure drop is presented in the form of an effective friction factor correlation which aligns closely with recent experimental data. The thermal performance of this heat exchanger, measured by its overall conductance under various flow conditions, was decomposed to examine the independent convection behaviors of both the CO2 and sodium streams. These results are presented in the form of Nusselt correlations fitted to the experimental data. The sodium heat transfer correlation aligns closely with the widely accepted Lubarsky-Kaufman correlation, while the CO2 heat transfer correlation lies between previous correlations developed by computational and experimental methods. This was the first long-duration use of sodium in a microchannels (∼ 1.8 mm hydraulic diameter) heat exchanger. The use of an oxide control system enabled trouble-free operation of the heat exchanger for over 150 h of high-temperature operation. This first-of-a-kind demonstration using liquid sodium and supercritical carbon dioxide shows great promise for further application of this technology in advanced nuclear or solar power plants.

Improved Performance of Latent Heat Energy Storage Systems in Response to Utilization of High Thermal Conductivity Fins

Analytical, computational and experimental investigations directed at improving the performance of latent heat thermal energy storage systems that utilize high thermal conductivity fins in direct contact with phase change materials are reviewed. Researchers have focused on waste heat recovery, thermal management of buildings/computing platforms/photovoltaics/satellites and energy storage for solar thermal applications. Aluminum (including various alloys), brass, bronze, copper, PVC, stainless steel and steel were the adopted fin materials. Capric-palmitic acid, chloride mixtures, dodecanoic acid, erythritol, fluorides, lauric acid, naphthalene, nitrite and nitrate mixtures, paraffins, potassium nitrate, salt hydrates, sodium hydrate, stearic acid, sulfur, water and xylitol have been the adopted fusible materials (melting or fusion temperature Tm range of −129.6 to 767 °C). Melting and solidification processes subject to different heat exchange operating conditions were investigated. Studies of thawing have highlighted the marked role of natural convection, exhibiting that realizing thermally unstable fluid layers promote mixing and expedited melting. Performance of the storage system in terms of the hastened charge/discharge time was strongly affected by the number of fins (or fin-pitch) and fin length, in comparison to fin thickness and fin orientation. Strength of natural convection, which is well-known to play an important role on thawing, is diminished by introduction of fins. Consequently, a designer must consider suppression of buoyancy and the extent of sacrificed PCM in selecting the optimum positions and orientation of the fins. Complex fin shapes featuring branching arrangements, crosses, Y-shapes, etc. are widely replacing simple planar fins, satisfying the challenge of forming short-distance conducting pathways linking the temperature extremes of the storage system.

Projected Hybrid Density Functionals: Method and Application to Core Electron Ionization.

This work introduces a new class of hybrid density functional theory (DFT) approximations, which incorporate different fractions of nonlocal exact exchange in predefined states such as core atomic orbitals (AOs). These projected hybrid density functionals are related to range-separated hybrid functionals, which incorporate different fractions of nonlocal exchange at different electron-electron separations. This work derives projected hybrids using the Adiabatic Projection formalism. One projects the electron-electron interaction operator onto the chosen predefined states, introduces the projected operator into the noninteracting Kohn-Sham reference system, and employs a formally exact density functional to model the remaining electron-electron interactions. Projected hybrids, like range-separated hybrids, approximate the partially interacting reference system's ground-state wave function as a single Slater determinant. Projected hybrids are readily implemented into existing density functional codes, requiring only a projection of the one-particle density matrices and exchange operators entering existing routines. This work also presents an application to core electron ionization. Projecting onto core atomic orbitals allows us to introduce additional nonlocal exchange into atomic core regions. This reduces the impact of self-interaction error on computed core electron properties. Benchmark studies are reported for PBE0c70, a core-projected variant of the Perdew-Burke-Ernzerhof global hybrid PBE0, in which the fraction of nonlocal exchange is increased from 25% to 70% in atomic core regions. PBE0c70-predicted core orbital energies accurately recover nonrelativistic core-electron binding energies of second-period elements Li-Ne and third-period elements Na-Ar, without degrading the good performance of PBE0 for atomization energies and valence ionization potentials.

Two quantum particles in one dimension involving the exchange operator

In this work, after introducing the main algebraic and representative properties of the quantum mechanics with Dunkl derivative, two-particle system with exchange symmetry is studied. In this framework, a new deformed derivative involving the exchange operator is proposed. With the help of such an operator, the new deformed quantum theory for systems with two quantum particles in one dimension is developed. As physical applications of the present construction, systems with two quantum particles interacting via the harmonic potential and the delta-function potential well are considered in detail. The wave functions and the energy spectra for these potentials are derived. Finally, possible implications of our results on other application areas of research such as in interacting theories of either bosons or fermions are concisely discussed.

On the modulation/energy competing of Tb(III)/Eu(III) emission in microporous MOF host for peroxide recognition

Being an important chemical reagent having moderate oxidizability, peracitic acid (PAA) has been applied in modern industries and processing, as well as public safety. These versatile applications make PAA an important analyte to be precisely and sensitively detected. The present work chose the combination of rare-earth-based probe and a microporous host bio-MOF-1 ([Zn8(ad)4(BPDC)6O·2(Me2NH2)+]·G, ad = adenine, BPDC = 4,4′-biphenyl dicarboxylic acid, G = N,N-dimetylformamide and water). Two β-diketone ligands, 1,3-di(pyridin-3-yl)propane-1,3-dione (DPY) and 1,3-diphenylpropane-1,3-dione (DPP), were coordinated to Tb(III) and Eu(III) ions to form probe [RE(DPY/DPP)2]Cl which was loaded into bio-MOF-1 micropores with different loading contents via an ionic exchange operation. The resulting composite samples were fully characterized, including synthesis, morphology, composition, sensing performance and mechanism. The protonation/oxidization of DPY and DPP ligands adjusted their triplet energy level (T1) and consequently affected their energy transfer (ET) efficiency to RE ions, resulting in the variation of RE emission relative intensity. A new pathway for PAA optical sensing was thus proposed. Linear fitting equations were observed for DPY-based samples, showing fluorescence intensity ratio value of 8.80, response time of 9 s, and LOD of 8.08 μM within working region of 0–140 μM.

Армия Российской империи как ретранслятор многовекторной мотивации в условиях Северного Кавказа первой половины XIX века

Introduction. The article is devoted to the peculiarities of the course of the Caucasian War at its initial stage of development and the roles of the Russian imperial army, which the military had to perform in the conditions of the realities of the North Caucasus in the first half of the 19th century. Materials and methods. Using published sources, the author turned to the method of historical reconstruction to achieve the research goal. Analysis. The author of the article draws attention to the fact that the Russian side actively influenced the developing situation in the region. Finding itself in climatic and geographical conditions that went beyond its previous experience, and meeting with peoples whose daily lifestyle was too different from those familiar to Russian habits, the army itself was forced to adapt to new challenges. Authorized military commanders have radically changed the strategic approaches and tactics of conducting combat operations in mountainous forest areas. The equipment, weapons and moral and psychological training of the troops participating in the expeditions against the highlanders have changed. At the same time, the imperial authorities, given the opportunities and means they had at that time, saw in the Caucasian troops not only a force capable and intended for crushing local Caucasian strongholds, but endowed the army with a peculiar mission to be a communicator of innovations brought by Russia to the Caucasus region. In this regard, the army was also instructed to be a conductor of various kinds of motivations, covering the socio-cultural and economic spheres of life of the conquered region, to strive in every possible way to involve the local population in them. Representatives of the mountain peoples were involved in the construction of roads, fortresses and bridges, participation in trade and exchange operations, which had the goal of overcoming distrust and hostility, as well as strengthening ties in everyday life. Often the headquarters of the army regiments became the centers providing innovations introduced by the Russians. Results. Based on the results of the study, it can be concluded that the Russian imperial army acted as the vanguard of the Russian world, with which it introduced the Caucasian peoples. Through the military St. Petersburg hoped to establish the type of communication with the local population (at first, at least part of it) that would allow achieving a tolerable mutual understanding in order to lay the foundation not only for peaceful coexistence but also for the transmission of imperial state-political messages to the Caucasus foundations.

Глобальная роль доллара и тенденции дедолларизации мировой экономики в новых условиях

The paper is devoted to the analysis of the role of the dollar in the world economy and its formation as a world reserve currency. Based on the methodology of the school of world-system analysis (J. Arrighi, S. Amin, I. Wallerstein, R.S. Dzarazov), the author reveals the mechanism for using the dollar as one of the instruments of unequal exchange between the center and the periphery of the economy within the American systemic capital accumulation cycle. Based on a comprehensive empirical analysis, an assessment is made of the trends in the de-dollarization of the world economy in the 21st century. It was found that despite the devastating consequences of the global crisis of 2007–2009. caused by the hypertrophied development of the financial sector of the US economy during the global crisis, the dollar retained a key role in the international reserves of states, in trade and exchange operations in the world economy. In particular, the Russian economy, despite the statements of the authorities about moving towards abandoning the dollar, nevertheless remained highly dependent on it, only partially replacing US dollars with the euro. Real de-dollarization 2022-2023 in Russia became a necessary measure for business, and was associated with the partial blocking of Russian correspondent accounts in Western banks.

A Two-dimensional Numerical Model of Heat Exchange in the Soil Massif During the Operation of a Shallow Horizontal Soil Heat Exchanger

The current article uses a two-dimensional numerical model to represent the results of theoretical studies of the heat exchange in the soil massif during the operation of a shallow horizontal soil heat exchanger. The analysis of literature sources showed that one of the important conditions for the effective operation of a shallow-soil heat exchange is its rational design parameters, such as the total length of the pipeline, the diameter of the pipe, the distance between the axis of the adjacent pipes, the depth of the heat exchanger placement, etc. A two-dimensional heat exchange model in the soil mass was developed, which made it possible to investigate the operation of a shallow horizontal soil heat exchanger. It was found that the step between the axis of the adjacent pipes of the multi-loop heat exchanger, which is 0.95 m, is optimal when creating a shallow horizontal soil heat exchanger in the soil conditions of Kyiv.

БАНКІВСЬКЕ ОБСЛУГОВУВАННЯ ЗОВНІШНЬОЕКОНОМІЧНОЇ ДІЯЛЬНОСТІ ПРОМИСЛОВИХ ПІДПРИЄМСТВ

Within the scope of banking services for the foreign economic activities of industrial enterprises, commercial banks keep funds in foreign currencies of such enterprises in current and deposit accounts, lend to the export and import activities of such enterprises, carry out international settlements, documentary, currency exchange operations, etc. The article examines the features of banking services for industrial enterprises at the current stage and defines its prospects and tools in the post-war period. It has been established that industrial enterprises try to keep cash balances in foreign currency in the most liquid form, so they either remain in current accounts or are converted into short-term deposits with a term of up to 1 year. Lending in foreign currency tends to decrease and is mostly short-term in nature. The main volume of loans in foreign currency is concentrated in the processing industry, in particular, half of them are in the food industry. As for long-term loans in foreign currency, they are concentrated on enterprises engaged in the supply of electricity, gas, steam and air conditioning, as well as enterprises of the metallurgical industry. Lending in US dollars is concentrated in the manufacturing industry, while lending in euros is predominant for enterprises engaged in the supply of electricity, gas, steam and air conditioning. There is practically no lending in other currencies. It is proposed to expand banking products of JSC "PUMB" for financing foreign economic activities of industrial enterprises through cooperation with international financial institutions, other domestic and foreign banks, leasing companies. Currently, servicing the foreign economic activities of industrial enterprises is not a priority area of activity, as JSC "PUMB" is reorienting itself to the retail segment and lending to agricultural producers, but in the conditions of post-war reconstruction, we believe that lending to industrial enterprises, in particular in a consortium with foreign banks and international financial organizations, should become one from strategic priorities.

A support vector machine training scheme based on quantum circuits

In order to improve the training efficiency of the support vector machine, a quantum circuit training scheme based on the inner product of the quantum state for the support vector machine is proposed in this work. Firstly, on the basis of the full analysis of the computational complexity of the classical support vector machine, the kernel function which is the main factor affecting the computational complexity of the algorithm is primarily analyzed. Based on quantum mechanics and quantum computing theory, the training sample elements in the kernel function are quantized to generate the corresponding quantum states. Secondly, according to the quantum states of the training sample elements, the types and quantities of the required quantum logic gates are derived and calculated, and the quantum circuit that can generate the corresponding quantum states of the training sample elements through the evolution of the quantum initial ground states and the quantum logic gates is designed. Then, in the light of the relationship between the inner product of the quantum state and the quantum logic gate SWAP, the quantum circuit is designed to complete the exchange operation of the corresponding quantum state amplitude. The inner product of the quantum state is realized by exchanging and evolving the amplitude of the quantum state in the quantum circuit. Finally, by measuring the quantum state of the controlling qubit, the inner product solution of the kernel function is obtained, and the acceleration effect of training support vector machine is realized. The verification results show that the scheme enables the support vector machine not only to complete the correct classification, but also to operate the quantum part of the scheme on the real quantum computer . Compared with the classical algorithm, the scheme reduces the time complexity of the algorithm for the polynomial degree, greatly shortens the training time of the model, and improves the efficiency of the algorithm. The scheme has certain feasibility, effectiveness and innovation, and expands the training idea of the support vector machine.

КРЕДИТНИЙ РИЗИК У СУЧАСНИХ УМОВАХ

The article carried out scientific research and investigated the problem of the correct interpretation of the concept of "credit risk". The norms of the current legislation of Ukraine regarding the definition of the concept of "credit risk (CR)", which is regulated as the amount of expected losses or damages (EL) for an asset as a result of the debtor’s (counterparty’s) default, have been analyzed. The concepts of "default" and "credit loss" are considered, the National Bank of Ukraine’s assessment of the credit portfolio due to the war is disclosed, the losses of which are estimated at the level of 30%, which poses a great threat to the banking sector. Changes to a number of regulatory documents regarding prudential credit risk assessment approaches have been analyzed: banks’ opportunities to apply simplified credit risk assessment procedures have been expanded; established temporary features of credit risk assessment to support banks in providing flexible conditions, socalled credit holidays, to borrowers in a period of uncertainty; an amendment was made to the Instruction on the Procedure for Regulating the Activities of Banks in Ukraine, which reduced the risk weight (RWA) from 150% to 100% for consumer unsecured loans. The restrictions on foreign currency exchange operations related to non-resident banks on the so-called "stop" conditions for the first group of the Foreign Currency Classifier to support the liquidity of banks have been substantiated. Innovations of the International Financial Reporting Standard IFRS (IFRS) were studied, which in the legal and economic context of the essence of credit risks provides for the concept of expected credit losses (which will always be greater than zero), which should reflect probable losses due to the ownership of financial assets. The means of reducing credit risks were analyzed, in particular, diversification: geographical and portfolio. Considering the specifics of credit risks, the specifics of credit transactions are substantiated. The criteria for assessing credit risks based on qualitative and quantitative analysis are revealed. It was concluded that the actual assessment of credit risks in financial terms is under the influence of credit risk on the financial results of business entities and banking institutions and the specifics of credit operations.