Key Operation Research Articles

Evaluation of a heat pump coupled two-stage humidification-dehumidification desalination system with waste heat recovery

Humidification and dehumidification (HDH) desalination technology has attracted wide attention in the field of small-scale dispersed fresh water demand, because of its advantages such as simple configuration, low investment, and utilization of low-grade renewable energy and waste heat. In this paper, a heat pump coupled two-stage humidification-dehumidification desalination system with waste heat recovery is proposed, where the waste heat is used to heat the feed seawater of the first-stage humidifier, and the brine leaving the bottom is further heated by the condenser of heat pump and then taken as the feed of the second-stage humidifier, while the evaporator of heat pump is used to recover the heat of humid air from the first-stage dehumidifier. Performance evaluation of the proposed system with various working fluids are conducted regarding the fresh water production mpw, gained output ratio (GOR), recovery ratio (RR), specific entropy generation stot, and unit cost of fresh water production Zpw, and parametric studies are performed to identify the key operating parameters. Results show that the largest entropy generation occurs in evaporator, followed by the first-stage humidifier and condenser. Taking R22 as the working fluids is corresponding to the largest mpw, while the lowest Zpw and stot, and the highest GOR are obtained by R600. Higher spraying temperature of the first humidifier T4 is conducive to improving the mpw and Zpw, but leading to a larger stot. The GOR increases first and then decreases with the rise of T4, and the peak value is 4.57 at T4 = 340.65 K. The mass flow rate ratio of the first stage MR1 has significant effects on the system performance. When MR1 is about 3.5, the mpw, GOR and RR reach the peak. However, the bottom value of Zpw is 8.74 $/m3 corresponding to the MR1 of 2.2–2.5. With the increase of compression ratio (CR) of heat pump subsystem, the mpw, GOR and RR climb up first and then decrease, while Zpw and stot get raised.

Towards a Provably Secure Authentication Protocol for Fog-Driven IoT-Based Systems

The emergence of fog-based Internet of Things (IoT) systems have played a significant role in enhancing the applicability of the IoT paradigm. In such systems, fog-nodes are proficient enough to retain, process and transmit the data coming from IoT devices. Nevertheless, as an extension of cloud computing, inheriting the security and privacy concerns of cloud computing is also inevitable in fog-based IoT systems. To deal with such challenges, a diverse range of security solutions are reported in the literature. However, most of them have several limitations (i.e., vulnerability to known security attacks and high computation overhead) that curtail their practical implementation applicability. Keeping these limitations in mind, this paper propose a privacy-preserving hash-based authenticated key agreement protocol using XOR and concatenation operations for fog-driven IoT systems. Using healthcare as a case study, the security of the novel protocol is evaluated by using informal and formal security analysis. In order to obtain the experimental results, the key cryptographic operations used at the user, fog node and cloud server-side are implemented on a mobile device, Arduino and cloud server, respectively. Findings from the performance evaluation results show that the proposed protocol has the least computation cost compared to several related competing protocols.

Bionic Design of Furrow Opener Based on Muskrat Claw-Toe Structure to Improve the Operating Performance of Deep Application of Liquid Fertilizer in Paddy Fields in Cold Region of China

The deep application of liquid fertilizer in paddy fields is a fertilization technique that applies liquid fertilizer deep near the root system of paddy field crops, which can effectively improve the absorption rate of the crops and reduce the amount of fertilizer applied. In the cold regions of China, the soil return rate of the furrowing operation of the deep application of liquid fertilizer in paddy fields is low, which can easily cause the excessive liquid leakage of fertilizer and affect crop growth. Therefore, it is difficult to popularize in large areas. According to the characteristics of paddy soil in the cold regions of China and the operating requirements of a high backfill rate and low disturbance rate of the soil of the deep application of liquid fertilizer, this paper designed a bionic liquid fertilizer deep application furrow opener based on the claw-toe structure of the muskrat. In this study, an indoor soil bin test was conducted by constructing a deep application environment for the liquid fertilizer in paddy fields. The results of the soil bin test showed the effects of the key operating parameters of the bionic design of the liquid fertilizer deep application furrow opener, spraying pressure of the liquid fertilizer and operating speed on the furrowing resistance, soil disturbance rate and the leakage amount of liquid fertilizer. The bionic design of the liquid fertilizer deep application furrow opener has a low soil disturbance rate and leakage amount of fertilizer when the operating speed is 0.8 m s−1, and the spraying pressure is 0.2 MPa. This furrow opener significantly improves the operating performance of the deep application of liquid fertilizer in the cold regions of China and is suitable for the deep application of liquid fertilizer in the paddy fields of this region.

Automated Library Generation and Serendipity Quantification Enables Diverse Discovery in Coordination Chemistry

Library generation experiments are a key part of the discovery of new materials, methods, and models in chemistry, but the question of how to generate high quality libraries to enable discovery is nontrivial. Herein, we use coordination chemistry to demonstrate the automation of many of the workflows used for library generation in automated hardware including the Chemputer. First, we explore the target-oriented synthesis of three influential coordination complexes, to validate key synthetic operations in our system; second, the generation of focused libraries in chemical and process space; and third, the development of a new workflow for prospecting library formation. This involved Bayesian optimization using a Gaussian process as surrogate model combined with a metric for novelty (or serendipity) quantification based on mass spectrometry data. In this way, we show directed exploration of a process space toward those areas with rarer observations and build a picture of the diversity in product distributions present across the space. We show that this effectively "engineers" serendipity into our search through the unexpected appearance of acetic anhydride, formed in situ, and solvent degradation products as ligands in an isolable series of three Co(III) anhydride complexes.

A Survey on Hyperdimensional Computing aka Vector Symbolic Architectures, Part II: Applications, Cognitive Models, and Challenges

This is Part II of the two-part comprehensive survey devoted to a computing framework most commonly known under the names Hyperdimensional Computing and Vector Symbolic Architectures (HDC/VSA). Both names refer to a family of computational models that use high-dimensional distributed representations and rely on the algebraic properties of their key operations to incorporate the advantages of structured symbolic representations and vector distributed representations. Holographic Reduced Representations [ 321 , 326 ] is an influential HDC/VSA model that is well known in the machine learning domain and often used to refer to the whole family. However, for the sake of consistency, we use HDC/VSA to refer to the field. Part I of this survey [ 222 ] covered foundational aspects of the field, such as the historical context leading to the development of HDC/VSA, key elements of any HDC/VSA model, known HDC/VSA models, and the transformation of input data of various types into high-dimensional vectors suitable for HDC/VSA. This second part surveys existing applications, the role of HDC/VSA in cognitive computing and architectures, as well as directions for future work. Most of the applications lie within the Machine Learning/Artificial Intelligence domain; however, we also cover other applications to provide a complete picture. The survey is written to be useful for both newcomers and practitioners.

Modelling of an integrated protonic ceramic electrolyzer cell (PCEC) for methanol synthesis

In this study, a novel reactor model is developed by combining protonic ceramic electrolyzer cell (PCEC) electrolysis for hydrogen production and CO2 recycling for methanol synthesis. The problem of temperature mismatch between PCEC and methanol synthesis is solved by supplying low-temperature gas intermediately, so as to realize the integrated direct synthesis of methanol. After model validation, a study of the effects of key operating parameters on the methanol production and temperature distribution of the system is conducted. It is found that increasing the operating voltage and electrolysis operating temperature, or decreasing the supplemental gas temperature enhances methanol production, while the carrier gas flow rate, supplemental gas flow rate and anode flow rate all have the optimal values (QN2 = 10–35 SCCM, QCO2 = 20–50 SCCM and Qan = 250–300 SCCM). Meanwhile, the temperature distribution of the system is also significantly affected by the above operating parameters, and it is possible to achieve a precise control of the operating conditions of the coupled system by adjusting the above operating parameters to ensure an efficient and long-term operation. This study provides an insight and a new approach for the recycling of CO2 and the green synthesis of methanol.

Physics-Based Reduced-Order Model for Liquid Ring Pumps

Abstract Liquid-ring vacuum pumps, by not having solid-solid contacts at interfaces where moving and stationary parts meet, are efficient and robust with considerable potential for further improvements on efficiency, performance, and range of operations. In this study, a physics-based reduced order model was developed for the preliminary design of liquid-ring pumps. The model developed accounts for the dominant physical processes created by the pump's key design and operating parameters: eccentricity, impeller-tip radius, impeller-hub radius, pressure at the pump's inlet and exit, and the impeller's rotational speed. The model developed can predict the shape of the liquid ring, the amount of air ingested and discharged by the pump, the power consumed by the pump as well as the pressure of the gas and liquid in the pump between the blades of the impeller as a function of those design and operating parameters. The predictions made by the model on the flow rates of the gas ingested by the pump and the power consumed by the pump were compared with experimental data, and good agreements were found.

Design, energy efficiency, and CO2 emissions analysis of a power generation process of coking dry gas reforming coupled with solid oxide fuel cell and organic Rankine cycle

Coking dry gas is a kind of refinery dry gas, which is rich in H2 and light hydrocarbon resources, but it’s often used as fuel, resulting in inefficient utilization of dry gas resources and a large amount of air pollutants emissions. Solid oxide fuel cell can efficiently convert the chemical energy of hydrogen into electricity. Therefore, this work establishes a model of a power generation process of coking dry gas reforming coupled with the solid oxide fuel cell and organic Rankine cycle. Process simulation is used to analyze the influence of key operating parameters on the system output performance. The obtained results indicate that the net electrical efficiency of the proposed system is increased from 45.45 % of the coking dry gas direct combustion for power generation system to 56.89 %. In terms of environmental impact, the CO2 emissions of the new system is 373.31 kg/MWh, 20.12 % lower than that of the direct combustion process. Besides, the effect of air excess ratio on system performance is evaluated and the net electrical efficiency of the proposed system increases to 63.73 % as the air excess ratio decreases from 2.0 to 1.1. The above results show that the proposed hybrid power system can provide an effective way for efficient and clean utilization of coking dry gas.

Standardized method for mechanistic modeling of multimodal anion exchange chromatography in flow through operation

Multimodal chromatography offers an increased selectivity compared to unimodal chromatographic methods and is often employed for challenging separation tasks in industrial downstream processing (DSP). Unfortunately, the implementation of multimodal polishing into a generic downstream platform can be hampered by non-robust platform conditions leading to a time and cost intensive process development. Mechanistic modeling can assist experimental process development but readily applicable and easy to calibrate multimodal chromatography models are lacking. In this work, we present a mechanistic modeling aided approach that paves the way for an accelerated development of anionic mixed-mode chromatography (MMC) for biopharmaceutical purification. A modified multimodal isotherm model was calibrated using only three chromatographic experiments and was employed in the retention prediction of four antibody formats including a Fab, a bispecific, as well as an IgG1 and IgG4 antibody subtype at pH 5.0 and 6.0. The chromatographic experiments were conducted using the anionic mixed-mode resin Capto adhere at industrial relevant process conditions to enable flow through purification. An existing multimodal isotherm model was reduced to hydrophobic interactions in the linear range of the adsorption isotherm and successfully employed in the simulation of six chromatographic experiments per molecule in concert with the transport dispersive model (TDM). The model reduction to only three parameters did prevent structural parameter non-identifiability and enabled an analytical isotherm parameter determination that was further refined by incorporation of size exclusion effects of the selected multimodal resin. During the model calibration, three linear salt gradient elution experiments were performed for each molecule followed by an isotherm parameter uncertainty assessment. Lastly, each model was validated with a set of step and isocratic elution experiments. This standardized modeling approach facilitates the implementation of multimodal chromatography as a key unit operation for the biopharmaceutical downstream platform, while increasing the mechanistic insight to the multimodal adsorption behavior of complex biologics.

A Fuzzy Modelling of a Hybrid MCDM Method for Supplier Selection

This article examines the significance of supplier selection in the procurement process, which has grown in prominence as a result of globalization and outsourcing. When selecting the best suppliers, supply chain managers must consider a variety of quantitative and qualitative aspects, as these have a substantial impact on supply chain performance. Multi-criteria decision-making (MCDM) approaches can help in this process by taking into account many competing considerations. However, due to uncertainties and ambiguity, supplier selection is a complex process, and fuzzy multi-criteria decisionmaking approaches can be used to determine the best supplier for the company's key operations. This research suggests a hybrid MCDM strategy that makes use of fuzzy modeling to help with complex decision-making processes. Organizations can improve their supply chain performance by selecting the best supplier based on numerous parameters such as cost, quality, delivery time, and supplier reputation.

ОРГАНИЗАЦИЯ АВТОМАТИЗИРОВАННОГО УЧЕТА НЕФТЕПРОДУКТОВ НА ОСНОВЕ МНОГОФУНКЦИОНАЛЬНОГО ПРОГРАММИРУЕМОГО КОНТРОЛЛЕРА ТОПЛИВНОГО СКЛАДА

The article is devoted to the actual problem of controlling the circulation of petroleum products in the warehouses of the service subsystem of an enterprise that supplies fuel to industrial vehicles. The processes of transportation of raw materials, materials, finished products, as well as the transportation of employees to remote work sites are important for the smooth functioning of the main production, and their cost reaches 25-30% of the cost of production. The purpose of the article is to study the problems of organizing automated accounting of petroleum products based on a multifunctional programmable controller of a fuel depot in service industries. The basis of the research methods was the dialectical and systematic approach, methods of formalization, modeling, methods of cause-and-effect relationships. To assess the pace of development of advanced production technologies, a statistical analysis of data dynamics was used, which makes it possible to determine priorities in the development of technologies, to identify the relationship between developments in a related direction. To visualize the technological processes in the fuel depot, which require the organization of automated control of petroleum products, the method of graphic descriptions of control processes was used, reflecting the route technology for performing managerial functions. The study of the organization of service industries of Russian enterprises showed the predominance of the use of manual control or the use of foreign information products for the purposes of accounting for petroleum products. Trends in the development of advanced production technologies have been identified that characterize the importance of creating equipment for automated transportation of materials, automated loading and unloading operations in the service subsystems of transportation and storage. The processes and operations at the transport fuel warehouse serving the transport subsystem of the main production are systematized. A schematic block diagram of technological processes at a fuel depot has been developed, requiring the organization of automated control and accounting of petroleum products. The functions of the control device are performed by the multifunctional controller of the fuel depot, for the operation of which it is necessary to provide connection of additional technological equipment. The duration of the technological cycle of operations at the fuel depot before and after process automation has been studied. For nine key operations, the time and cost of performing work are presented, the time and economic effect from the introduction of a multifunctional programmable controller is calculated, which is, respectively, 7.61% and 19.48 thousand rubles as a whole for the full technological cycle. The research materials have theoretical and practical significance, they can be used in the development of scientific investment projects for the creation and implementation of automated fuel storage systems based on a multifunctional programmable controller in the practice of organizing servicing production processes.

Th e montage film: from the document-image (of archive) to the actual audiovisual production

It is somewhat unusual that the montage fi lm (documentary) does not yet benefi t from a well-defi ned aesthetic status, starting from its name itself. In the few specialized works that refer to this kind of audiovisual production, especially of Russian expression, various defi ning features are used: “compilation fi lm”, “archive fi lm”, “cinematheque (mediatheque) fi lm”, “documentary-archival fi lm”, etc. We believe that the most appropriate name would be “montage fi lm”, because the given phrase encompasses a fundamental concept both for cinematographic art and, in terms of the theory and practice of the respective genre or format, namely, the montage (key operation in the edifi cation of the expected audiovisual reality). We also undertook a foray into the history of montage fi lm, bringing to the fore illustrious names and signifi cant examples from Soviet cinematography: Dziga Vertov, Esfi r Shub and Mikhail Romm. Other montage fi lms intended to complete our applicative analysis were taken from the Romanian audiovisual space, as well as from that of the Republic of Moldova.

Evaluation and Analysis of Flux-Regulated Permanent Magnet Linear Eddy Current Brakes

In this study, a novel permanent magnet linear eddy current brake based on the field regulation theory is presented, and the corresponding analytical model is developed. By shifting transversely the field-regulated plate, the real-time and easy control of the braking force can be achieved, which is the intent of the proposed topology. The key structure and operation principle are addressed. In addition, to avoid the excessive computation time and cost when using the numerical method, a practical analytical model for calculating the electromagnetic and force performance is established based on the magnetic equivalent circuit method with variable reluctance. The validity of the model is verified using the 3-D finite element analysis and equivalent prototype experiments. Moreover, further analysis is carried out to investigate the effects of the key geometrical parameters on the braking force-speed characteristic.

Lightweight Authentication Scheme for IoT Based E-Healthcare Service Communication.

Remote Patient Monitoring (RPM) using Electronic Healthcare (E-health) is a growing phenomenon enabling doctors predict patient health such as possible cardiac arrests from identified abnormal arrythmia. Remote Patient Monitoring enables healthcare staff to notify patients with preventive measures to avoid a medical emergency reducing patient stress. However weak authentication security protocols in IoT wearables such as pacemakers, enable cyberattacks to transmit corrupt data, preventing patients from receiving medical care. In this paper we focus on the security of wearable devices for reliable healthcare services and propose a Lightweight Key Agreement (LKA) based authentication scheme for securing Device-to-Device (D2D) communication. A Network Key Manager on the edge builds keys for each device for device validation. Device authentication requests are verified using certificates, reducing network communication costs. E-health empowered mobile devices are store authentication certificates for future seamless device validation. The LKA scheme is evaluated and compared with existing studies and exhibits reduced operation time for key generation operation costs and lower communication costs incurred during the execution of the device authentication protocol compared with other studies. The LKA scheme further exhibits reduced latency when compared with the three existing schemes due to reduced communication costs.

Deriving high value products from depolymerized lignin oil, aided by (bio)catalytic funneling strategies.

Lignin holds tremendous and versatile possibilities to produce value-added chemicals and high performing polymeric materials. Over the years, different cutting-edge lignin depolymerization methodologies have been developed, mainly focusing on achieving excellent yields of mono-phenolic products, some even approaching the theoretical maximum. However, due to lignin's inherent heterogeneity and recalcitrance, its depolymerization leads to relatively complex product streams, also containing dimers, and higher molecular weight fragments in substantial quantities. The subsequent chemo-catalytic valorization of these higher molecular weight streams, containing difficult-to-break, mainly C-C covalent bonds, is tremendously challenging, and has consequently received much less attention. In this minireview, we present an overview of recent advances on the development of sustainable biorefinery strategies aimed at the production of well-defined chemicals and polymeric materials, the prime focus being on depolymerized lignin oils, containing high molecular weight fractions. The key central unit operation to achieve this is (bio)catalytic funneling, which holds great potential to overcome separation and purification challenges.

Optimization of maritime transportation based on marketing technologies

The paper deals with actual questions, related to development of maritime transport communications based on marketing approach. Usage of marketing tools (formation and adjustment of key expectations and needs for the target audience) enables more integrated approach to maritime transport operation and realization of it’s potential more systematically. The article presents expectations and needs of the key shipping route operators based on three-dimensional matrix (consumers-feature of needs- technology ‘know-how’ to cover needs), the most important factors development are analyzed with reference to local specific features to cover needs and preferences of shippers in highly competitive maritime transport market. On this basis, the author’s point of view on future perspectives of maritime transport communications development and it’s competitive growth is proposed. In order to attract operators’ attention to maritime route activities and fully involve it’s transport potential in economic turnover it’s necessary to create and develop of coastal infrastructure, the functioning of monitoring systems, and measures implementation to ensure navigation safety. The intensification of shipping and freight traffic growth will create effective maritime transport direction and stimulate business activity.

ВПЛИВ ТРАНСНАЦІОНАЛЬНИХ КОРПОРАЦІЙ НА РЕАЛІЗАЦІЮ ЦІЛЕЙ СТАЛОГО РОЗВИТКУ

The role of public authorities in the process of implementing the SDGs is determined on the example of the analyzed group of foreign countries (USA, UK, Germany, France and Japan): an important function of state regulation is noted in terms of overcoming “market failures” and internalizing social and environmental costs. It has been established that the process of adapting state policies to the 2030 Agenda is currently underway; the political leadership of the countries under consideration initiates the formation of mechanisms for the interaction of various stakeholders in the interests of the implementation of the SDGs at the national and global levels. The factors that encourage transnational businesses to participate in the implementation of the SDGs are analyzed: the possible benefits acquired by the private sector as a result of this activity (creation of long-term qualitative "value" and short-term quantitative "value" are investigated and evaluated); specific business cases are described that prove in practice the commercial feasibility of companies' activities in the interests of the SDGs; shows the relationship between financial and non-financial indicators of the business. The main ways of participation of transnational business in the implementation of the SDGs at the present stage (FDI, the implementation of the SDGs through key business operations, social and green investments, the promotion of individual SDGs within corporate strategies, "mixed" financing) are identified and described. models of such participation (philanthropic, commercial, hybrid). Based on the author's analysis of the key areas of participation of transnational businesses in the implementation of the SDGs, content analysis of non-financial reporting and financial performance of the largest and most socially responsible TNCs in the world, as well as an analysis of the activity of the private sector in transactions of "mixed" financing, an assessment was made of the involvement of transnational businesses in the implementation of the SDGs at the present stage.

An experimental study of the effects of key operating parameters on the molten carbonate fuel cell performance

Proper selection of the operating conditions of molten carbonate fuel cells (MCFCs) can not only effectively improve the efficiency of power generation, but also reduce carbon emissions and help achieve the great goal of “carbon neutrality”.

Comparisons and Improvements of Key Operating Characteristics of Current Source Converter Applied in HVDC System

Comparisons and Improvements of Key Operating Characteristics of Current Source Converter Applied in HVDC System

Разработка метода весового непрерывного дозирования сыпучих материалов и анализ его реализации

Weight continuous dosing of bulk materials is one of the key operations in many technological processes. As a result of analyzing methods and devices of the weight continuous dosing used by the world’s leading manufacturers of dosing systems, it was found that the main reason of decrease in the accuracy of dosing was the dynamic effects on the weight sensor. The material motion in the process of weight measuring causes these effects. The lowest dynamic impacts on the load sensor were observed when using the two-stage dosing technology. The essence of this technology lies in the fact that at the first stage separate portions with fixed weight are formed, which are fed into a vibrating tray at regular intervals and are converted into a continuous flow at the second stage. The portion weight and the time interval values are selected from the condition of equality of the given dispenser productivity to the ratio of the individual portion weight to the time interval between the supply of portions to the device for their conversion into a continuous flow. Dynamic impacts on the sensor are reduced, but are not completely excluded, since the weight of a separate portion is determined during the material motion. To increase the dosing accuracy, a new strategy in implementing the two-stage dosing technology is proposed based on the fact that constancy of the quotient could be ensured not only with the constancy of the dividend and the divisor, but also with variable values of these quantities. The proposed dosing method was experimentally compared with the prototype, which confirmed advantages of the new dosing strategy over the traditional one.