Theoretical Model Of System Research Articles

Combination of Concave and Convex Paraboloids: Theoretical Model of New-type Daylighting System

Combination of Concave and Convex Paraboloids: Theoretical Model of New-type Daylighting System

Impact of fiber dispersion on the performance of entanglement-based dispersive optics quantum key distribution

Dispersive optics quantum key distribution (DO-QKD) based on energy-time entangled photon pairs is an important QKD scheme. In DO-QKD, the arrival time of photons is used in key generation and security analysis, which would be greatly affected by fiber dispersion. In this work, we established a theoretical model of the entanglement-based DO-QKD system, considering the protocol, physical processes (such as fiber transmission and single-photon detection), and the analysis of security tests. Based on this theoretical model, we investigate the influence of chromatic dispersion introduced by transmission fibers on the performance of DO-QKD. By analyzing the benefits and costs of dispersion compensation, the system performance under G.652 and G.655 optical fibers are shown, respectively. The results show that dispersion compensation is unnecessary for DO-QKD systems in campus networks and even metro networks. Whereas, it is still required in DO-QKD systems with longer fiber transmission distances.

Enhancing efficiencies of solar thermophotovoltaic cells by downconversion of high-energy photons

To better suit the bandgap of solar cell, we proposed a novel theoretical model of solar thermophotovoltaic system, which consists of a concentrator, a surface-textured absorber, an emitter, a photovoltaic cell, and a downconversion layer. Two configurations of rear and front down converters are proposed to enhance the performance of the solar thermophotovoltaic system. The corresponding expressions of particle and heat fluxes are derived. Based on balance equations of particle and energy, the temperatures of emitter and solar cell, and the voltages of down converter are determined. In addition, the influences of solar concentration ratio, geometrical factor, and refractive indexes of emitter and solar cell are considered. Moreover, the operating voltage of solar cell, the areas of emitter and solar cell, and the bandgap of solar cell are optimized at the maximum efficiency condition. The results show that the existence of down converter can efficiently enhance the performance of the solar thermophotovoltaic system, and the proposed configurations can provide theoretical guidance for efficient solar energy harvesting.

Understanding the effect of the MFI framework on the mechanism and kinetics of direct CH3COOH formation from the Co-activation of CO2 and CH4

Nowadays, theoretical calculations are playing a pivotal role in understanding the underlying reaction mechanism and at the same time used for exploration of the zeolite-based catalysts. For such systems, an inconsistency is seen in formulating the active site and choosing the size of the zeolite framework. Herein, we have formulated the standard theoretical model for the MFI-based catalytic systems considering the most recent experimental findings.[1] The formulated model is used for the explanation of the mechanism of acetic acid formation by the co-activation of CO2 and CH4 over the MFI based catalyst, which excellently justifies the experimental results. The following conclusions are drawn from the work, a sufficiently large zeolite framework is critical to validate the experimental findings. The extended zeolite framework is crucial for accurate optimization of the active site, drawing the plausible mechanisms and predicting the correct rate-limiting step of the reaction. Moreover, the neighbor Al-Al atoms must be kept away from each other by at-least two Si-centers to be consistent with the experiment.

Aptamer Conformational Change Enables Serotonin Biosensing with Nanopipettes.

We report artificial nanopores in the form of quartz nanopipettes with ca. 10 nm orifices functionalized with molecular recognition elements termed aptamers that reversibly recognize serotonin with high specificity and selectivity. Nanoscale confinement of ion fluxes, analyte-specific aptamer conformational changes, and related surface charge variations enable serotonin sensing. We demonstrate detection of physiologically relevant serotonin amounts in complex environments such as neurobasal media, in which neurons are cultured in vitro. In addition to sensing in physiologically relevant matrices with high sensitivity (picomolar detection limits), we interrogate the detection mechanism via complementary techniques such as quartz crystal microbalance with dissipation monitoring and electrochemical impedance spectroscopy. Moreover, we provide a novel theoretical model for structure-switching aptamer-modified nanopipette systems that supports experimental findings. Validation of specific and selective small-molecule detection, in parallel with mechanistic investigations, demonstrates the potential of conformationally changing aptamer-modified nanopipettes as rapid, label-free, and translatable nanotools for diverse biological systems.

State leakage during fast decay and control of a superconducting transmon qubit

Superconducting Josephson junction qubits constitute the main current technology for many applications, including scalable quantum computers and thermal devices. Theoretical modeling of such systems is usually done within the two-level approximation. However, accurate theoretical modeling requires taking into account the influence of the higher excited states without limiting the system to the two-level qubit subspace. Here, we study the dynamics and control of a superconducting transmon using the numerically exact stochastic Liouville–von Neumann equation approach. We focus on the role of state leakage from the ideal two-level subspace for bath induced decay and single-qubit gate operations. We find significant short-time state leakage due to the strong coupling to the bath. We quantify the leakage errors in single-qubit gates and demonstrate their suppression with derivative removal adiabatic gates (DRAG) control for a five-level transmon in the presence of decoherence. Our results predict the limits of accuracy of the two-level approximation and possible intrinsic constraints in qubit dynamics and control for an experimentally relevant parameter set.

Mathematical Analysis of Criteria for Maintenance of Technical Systems in the Function of Achieving Sustainability

Achieving sustainable development requires strategic efforts involving the entire organization. Maintenance efforts also play an important role. Company management needs to understand and develop an appropriate strategy to achieve sustainable development by applying maintenance performance measurements. The aim of this paper is to present possible ways of analyzing and ranking the impact of certain criteria with respect to achieving sustainability. The paper uses the method of Structural Equation Modeling—SEM in order to determine the most influential variable on the sustainability of maintenance of technical systems. Based on the set theoretical system model, for all its variables in the model, statements were made that describe them, on which 136 respondents gave their views (from 1 to 5, Likert scale) in the territory of the Republic of Serbia. An intuitive F-DEMATEL method was also used to prioritize variables. A team of 10 experts in the field of maintenance of technical systems was compared the criteria A—Application of technical diagnostics, B—Management of maintenance resources, C—Maintenance process planning, and the dependent variable D—Sustainability of maintenance of technical systems. According to experts, the importance of the criteria coincides with the results obtained by a survey with 136 respondents.

A Parametric Study of Compliant Link Design for Safe Physical Human–Robot Interaction

SUMMARYRobots of next-generation physically interact with the world rather than be caged in a controlled area, and they need to make contact with the open-ended environment to perform their task. Compliant robot links offer intrinsic mechanical compliance for addressing the safety issue for physical human–robot interactions (pHRI). However, many important research questions are yet to be answered. For instance, how do system parameters, for example, mechanical compliance, motor torque, impact velocities, and so on, affect the impact force? how to formulate system impact dynamics of compliant robots, and how to size their geometric dimensions to maximize impact force reduction. In this paper, we present a parametric study of compliant link (CL) design for safe pHRI. We first present a theoretical model of the pHRI system that is comprised of robot dynamics, an impact contact model, and dummy head dynamics. After experimentally validating the theoretical model, we then systematically study the effects of CL parameters on the impact force in more detail. Specifically, we explore how the design and actuation parameters affect the impact force of pHRI system. Based on the parametric studies of the CL design, we propose a step-by-step process and a list of concrete guidelines for designing CL with safety constraints in pHRI. We further conduct a simulation case study to validate this design process and design guidelines.

A Linearized Analog Microwave Photonic Link With an Eliminated Even-Order Distortions

An improved linearized analog microwave photonic link (AMPL) with significant multioctave bandwidth performance is experimentally presented. The proposed AMPL configuration is based on a double dual-parallel Mach–Zehnder modulator and a differential balanced photodetector (BPD). Explicitly, a gallium arsenide (GaAs)-based modulators are used as opposed to the commonly known lithium niobate (LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) modulators, due to its robustness in the harsh environment. The system configuration is designed to process a carrier suppressed double-sideband signal through the link, and then at the receiver, a carrier suppressed double-sideband signal is combined with an unmodulated optical carrier, which is transmitted through a polarization maintained (PM) optical fiber. In our experiment, only PM-based optical components are used for better system stability. The developed theoretical model of the proposed system illustrates the elimination of even-order distortions and a high suppression to the third-order intermodulation distortions at the BPD. Consequently, the fundamental signal to interference ratio of 60 dB was experimentally achieved. Furthermore, experimental results, simultaneously, demonstrate a significant increase of second-order spurious-free dynamic range and third-order spurious-free dynamic range by 19.5 and 3.1 dB, respectively, compared to the previously reported AMPL performances based on polarization multiplexing dual-parallel Mach–Zehnder modulator. To the best of our knowledge, this is the highest dynamic range AMPL system performance deploying GaAs electro-optic modulator which has most significant capabilities in managing RF signals and exhibits excessive performance in harsh operating environment in terms of thermal stability, power-handling, radiation resistance and longevity for aerospace, defense, and satellite-to-ground downlink communication system applications.

Reducing Diffusion-Induced Stress of Bilayer Electrode System by Introducing Pre-Strain in Lithium-Ion Battery

AbstractLithium-ion battery (LIB), as energy storage devices, is widely used in portable electronic devices and have promising applications in electric vehicles. The volume change and large stress can lead to electrode pulverization and the resultant loss of electrical contact from the current collector, which is considered to be one of the main reasons for the capacity degradation of LIB. To reduce diffusion-induced stress of the electrode system during lithium-ion diffusion, a chemo-mechanical coupled theoretical model of bilayer electrode system of electrode layer bonded to the current collector is established. The theoretical results show that diffusion-induced stresses at the electrode–collector interface and maximum tensile stress at the top surface of the electrode layer are alleviated greatly by introducing pre-strain. The effects of pre-strain and lithium-ion concentration on chemo-mechanical coupled behavior of the bilayer electrode system are discussed. In particular, the lithium-ion concentration difference strongly depends on the diffusion thickness and time. The curvature when considering plastic deformation is smaller than that when not considering the plastic deformation. In addition, the effects of plastic deformation of the current collector and diffusion time on biaxial stress distribution are also discussed. The biaxial stress decreases with the increase of pre-strain and decrease of dimensionless time during galvanostatic charging. The biaxial stress when considering plastic deformation is smaller than that when not considering the plastic deformation. The results obtained from this investigation will provide a reference to reduce the diffusion-induced stress and improve the ion diffusion performance of LIB.

Model of a Sustainable Transport System on the Example of Olsztyn

The main aim of the article is to present a theoretical model of a sustainable urban transport system and to indicate the need for changes in the approach to it. The issues of sustainable development and functioning of the municipal transport system in Olsztyn discussed in the article evoke vivid social and political interests of the city's inhabitants. This is mainly due to the impact of transport operation on quality of life, the correlation of its development with the economic development of the city, and the strong impact of transport on the natural environment. Today, it is already known that a coherent and modern transport system is an indispensable element of a competitive city. Connecting the city into a functional system, it presents it as a system of interdependencies between its elements.

Research on hot air ice melt system for cable sheaths of Er’qi Yangtze River Bridge

To prevent the cable sheaths of Er’qi Yangtze River Bridge from freezing under bad weather in winter, which may lead to ice fall and bring traffic safety accidents, a theoretical model and technical scheme of hot air ice melt system for Er’qi Yangtze River Bridge has been proposed. Based on the established heat transfer model for cable sheaths, the characteristics of heat transfer between internal hot air and outdoor environment have been analyzed. Under the condition when the temperature of the end of cable sheath’s outwall is more than 3°C, the range of temperature and speed of input hot air were estimated, which provides a theoretical basis for hot air melt system for cable-stayed bridge sheaths.

ІННОВАЦІЙНО-ІНВЕСТИЦІЙНА СИСТЕМА АПК: КОНЦЕПТУАЛЬНІ ЗАСАДИ

The article substantiates the basic principles of the functioning of the innovation-investment system of the agro-industrial complex as a complex interaction of subjects, relevant institutions, objects of innovation and financial infrastruc-ture, which contribute to the development, dissemination and implementation of innovations in agro-industrial production. The purpose of the article is to form the conceptual foundations of the innovation-investment system of the agro-industrial complex in the crisis macroeconomic conditions of management. The importance is substantiated and the main aspects of the innovation-investment system of the agro-industrial complex based on a systemic approach have been highlighted.The spe-cifics of the formation of the innovation-investment system of the agro-industrial complex is related to the need to overcome negative factors that affect the development of innovative activities, the implementation of investment projects for the devel-opment of agribusiness enterprises and, at the same time, are related to the deepening of the crisis in the economy.The prior-ity tasks and conditions of operation of the innovation-investment system of the agro-industrial complex have been deter-minedsuch as: improvement of the institutional environment of innovation and investment development; implementation of direct and indirect support of agro-industrial complex enterprises in the creation and development of innovations; the devel-opment of effective forms of cooperation between the state and business based on long-term partnership; training of highly qualified personnel in the field of organization and implementation of innovative activities for agro-industrial complex at the micro, meso, and macro levels; promoting the development of the material and technical base of the agro-industrial complex; development of international cooperation in the field of innovation. A theoretical organizational model of the innovation-investment system of the agro-industrial complex in the context of the implementation of the state innovation policy is pro-posed.It is justified that the components of the system are the subsystem of formation of knowledge potential, the subsystem of education, the subsystem of innovative activity, the subsystem of technological infrastructure, the subsystem of financial infrastructure, and the subsystem of information infrastructure.

Proposal to Improve the Management System of Storage in a Virtual Learning Environment

This article introduces a theoretical model of a storage management system for big data-based virtual learning environments. The system uses artificial intelligence technologies such as machine learning and deep learning to explore strategies for optimizing how stored data is processed. To this end, the storage management requirements currently presented by these platforms, as well as big data techniques and tools, and their applications on those platforms were investigated. This model is designed to be distributed, scalable, fast, and fault tolerant. In addition, it is expected to work with any web application that needs to improve file downloads.

Modeling of supply processes for perishable foodstuffs

Contemporary experience has proved the necessity of ensuring unity in the transport and logistics systems of food supplies. This is particularly relevant for perishable goods, the acceleration of delivery dates directly impacts their safety and quality. The article considers the problem of creating an effective transport process for perishable food supply chains. The analysis of influencing the efficiency of perishable food supply chains and the main principles and approaches to improve the transport support of perishable food products have been substantiated. The constructed theoretical model of a technological transportation system for perishable food goods considers compatibility (adaptability) of transport machines with agricultural machinery; technological parameters of technical systems; adaptability of technical systems to environmental conditions and technological properties of perishable food cargoes; transport and technological cycles parameters.

ПРИНЦИПЫ ВЫБОРА КОНТЕЙНЕРОВ ДЛЯ СТЕГАНОГРАФИЧЕСКИХ СИСТЕМ

In this study, the general principles of choosing containers to create perfect steganographic systems, as well as the characteristics, types, volume, size, format, stability of containers against attacks are considered. The process of entering information into a container is described, and the stability of steganograms with respect to passive and active attacks is analyzed. The distinguishing aspects of the formats of modern graphic containers, the advantage and disadvantages of the Internet protocols TCP, IP, VoIP and SCTP which are used as containers are discussed. To determine the effect of containers on steganographic stability, a theoretical information model of steganographic system with a passive intruder has been suggested. The dependence of the stability of steganographic systems on the technology of introducing hidden messages into a container is explained and the probability distributions of containers and steganograms are analyzed. It was shown that the stability of steganographic systems depends on the probability distributions of containers and steganograms, and only in the case they are identically distributed, the steganographic system is completely stable.

�����Dz� �� �������Բ� �. �. ������� ������ֲ� � ������������: �����̲�Ͳ ������� � ��ֲ��������Ͳ� ����ֲ̲� (��²� : ���-�� ����, 2017. 574 �.)

This material is a review of the book by Bohdan Shevchyk �Tradition and economy: economic systems in socio-cultural dynamics� (2017), which presents author�s concept of undestending socio-cultural changes as the basis of economic development. The monograph substantiates the concept of economic orientalism, which is considered in such dimensions: firstly, as a new paradigmatic project of socio-economic development; secondly, as forms of sociocultural space. The ideational type of cultural mentality of Ukrainians acts as the leading one and determines the structure and institutional complementarity of the national economic system of Ukraine. The main results of the author�s research, which characterize the scientific novelty, include the following: theoretical substantiation of the concept of economic orientalism as a characteristic of a number of modern circumstances, which is associated with: the change of types of dominant culture in the processes of sociocultural dynamics and the transition from sensory to ideational type of cultural mentality; proving the socio-cultural context of the formation of economic orientalism. Business entities are considered as a multi-intellectual socio-cultural economic system of the ideational type of culture; interpretation of systems of economic thinking as structures of mentality, which is the basis of theoretical modeling of evolutionary and transitive economic systems in the quadratic: structure-function-processenvironment

Mechanism of Vibration Energy Action on Dynamic Instability of Shock-Type Rockburst Carrier System

In coal mining, the rockburst intensity triggered by the mine earthquake is often greater in the mining area, and the precursor information is more difficult to capture. In this paper, this kind of rockburst is called shock-type rockburst and studied as the research object. Based on the evolution process and the theoretical model of the carrier system, the energy criterion of the occurrence of shock-type rockburst was deduced based on the theories of mathematics and statistical physics. The results showed that the process of shock-type rockburst can go through four stages: inoculation stage, occurrence stage, development stage, and termination stage, and the secondary triggering phenomenon may occur in the occurrence stage. The theoretical model of the shock-type rockburst carrier system was constructed, and the key characteristic parameter of shock-type rockburst was put forward. Then, the energy of mine earthquake was quantitatively characterized in the form of kinetic energy of rock block. Through the combination of the two parameters, the energy criterion of shock-type rockburst was obtained as follows: once the energy of mine earthquake acting on the rockburst source area was 2%–9% of the static energy, shock-type rockburst can occur. Then, this criterion was verified by three typical cases. Finally, based on the distribution conditions of “red seam” overburden in the Yanzhou mining area of China, the secondary triggering principle of rockburst was expounded, that is, the secondary triggering principle of rockburst caused by the shear fracture and sliding settlement of “red seam” overburden. To sum up, a theoretical system for judging the instability of the shock-type rockburst carrier system was formed. This study provides a theoretical basis for earthquake prevention and disaster reduction in coal mining.

Study of dynamic performance of radiation collector and thermocline system under time-varying radiation environment

The dynamic processes of coworking between thermocline thermal storage single (TES) tank and solar collector is studied for their application in solar concentrated power (CSP) plant. The TES tank uses packed-bed ore as heat storage material. Both experimental and numeric methods are conducted to build its theoretical model, which is used in the simulation of the whole CSP system. The theoretical model of the CSP system mainly composes of three parts: solar radiation, solar collector, and TES tank. It is simulated in the location of city Nanjing, China, to study its dynamic performance in the corresponding solar radiation environment in 4 seasons. The result of simulation shows that the CSP system with TES has stable performance while the solar radiation input varies with hour and season. According to the local solar environmental parameters, (the solar radiation energy density within one day of about 28 MJ/m2, and daytime of about 12 h), the solar system with solar collector and thermocline TES tank of proper capacity is designed. In the absence of sunshine during night, the system could supply heat of 225 kW for 12 h continuously, with an efficiency around 51%. With the similar research methods, it is feasible to assess the performance of thermocline TES single tank in CSP system.

Development and initial psychometric testing of the Intrahospital Transport Safety Scale in intensive care

ObjectiveTo develop and evaluate the psychometric properties of a scale measuring patient safety during the intrahospital transport process for intensive care.DesignThe scale was developed based on a theoretical model of...