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  • Open access
  • 23 Reads
Assessment of the decarbonization pathways of the cement industry in Uzbekistan

Cement production is one of the key industries responsible for emissions of greenhouse gases, especially carbon dioxide (CO2), which influence climate change. In order to reach zero carbon cement industry, various deep decarbonization pathways involving carbon capture, storage, and utilization (CCSU), using low-carbon material and fuel, optimal process control, and waste heat utilization techniques must be implemented. As for the example of Uzbekistan, approximately 30 facilities generate more than 17 Mt of cement annually and are responsible for 11.3% of the country's total CO2 emissions. In this study, decarbonization pathways for cement plants in Uzbekistan including CCSU, use of alternative fuels, electrification, and waste heat integration techniques are compared based on existing challenges and opportunities. The availability of alternative fuel and material resources suitable for the total production capacity, the comparison of post combustion, pre-combustion, and oxyfuel combustion CCSU methods for the cement plant, and the use of energy-efficient technologies are discussed.

  • Open access
  • 20 Reads
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The process of separation by crystallization of an industrial mixture of perfluorinated cycloalkanes, products of electrochemical fluorination of naphthalene, is considered. The content of the target products – cis- and trans-isomers of perfluorodecalin (PFD) in all initial fractions of the investigated samples of the reaction mixture was more than 70 wt %, the mixture itself was taken directly from industrial plant. In this work the distribution of components (target products, identified and unidentified impurities; the nomenclature of the latter is unknown because of the difficulties during their purifying that is required to identify their structure and, accordingly, the lack of relevant scientific studies) is shown by composition in solid and liquid phases. Based on experimental data the dependences of the crystallization (partition) coefficients between the solid and liquid phases (Ds/l) and recovery ratio on proportion between trans-PFD and cis-PFD contents, presence of low- and high-melting impurities and crystallization temperature in the range -50÷-10 ºС were obtained. According to the experimental data, the Ds/l value significantly depends on the presence of trans-PFD in the initial solution. Thus, with an increase in the ratio of trans-PFD/cis-PFD: the Ds/l value for the low-melting identified as perfluoro(butylcyclohexane) (BCH) impurity tends to 0 – BCH is completely absent in the solid phase; the majority of unidentified impurities are concentrated in the mother liquor (Ds/l< 1); the Ds/ltrans-PFD value has a linear dependence with the point of inversion at the ratio of trans-PFD/cis-PFD = 1; Ds/lcis-PFD≥ 1 for almost all trans-PFD/cis-PFD ratios and Ds/lcis-PFD ≫ 1 at trans-PFD/cis-PFD < 1. The latter is very interesting given that the melting point of cis-PFD is lower than that of trans-PFD. Thus, according to the experimental data the crystallization of the fractions with high trans-PFD content is less effective than that with high cis-PFD content.

  • Open access
  • 46 Reads
Combining COMSOL modelling with different Piezoelectric Materials to design MEMS cantilevers for marine sensing robotic

An advancement in underwater acoustic sensors has been made using MEMS cantilevers for marine sensing robotics. A directional hydrophone is formed by these MEMS cantilevers that detect the direction from which the incoming signal is coming. Due to their micrometre size and lightweight, these hydrophones can be mounted in autonomous underwater vehicles such as AUVs and ROVs. We can locate enemy submarines, underwater drones, and warships through this microsensor, thus improving our defence. Furthermore, this Vector Hydrophone will aid in developing submarine communication systems, sonobuoys, ROVs, SONARs, fish tracking, oceanographic surveys, and marine life surveys.
During the past two decades, microelectromechanical systems (MEMS) have attracted many researchers, especially microsensors and actuators. Among them, pressure sensors are essential. Different types of pressure sensors exist based on various physical properties, such as piezoresistive, piezoelectric, capacitive, magnetic, and electrostatic. This work presents a novel, highly sensitive, and directional piezoelectric cantilever-based micro-electro-mechanical system (MEMS) device realized by a biomimetic approach of the fish lateral line system for marine sensing robotics. The device will consist of ten cantilevers with different lengths in a cross-shape configuration made by a piezoelectric thin film (PZT, ZnO, BaTiO3 ) embedded between the top and bottom metals (Pt/Al) used as electrodes. This unique design of cantilevers in circular shape has the advantage of directional response in the frequency range of 300 Hz to 300 kHz. A comparative study of these piezoelectric materials was performed analytically through a finite element method to design, model, and simulate our device in COMSOL software. Solid mechanics, electrostatic and pressure acoustic are the physics used to study the behaviour of the microcantilevers. The simulations of cantilever microstructures with different lengths are performed from 100 μm to 1000 μm. The micro-cantilever consists of metal (Pt/Al) as electrodes and piezoelectric materials (PZT, ZnO, BaTiO3 ) on a silicon substrate. As a result of varying pressure, we studied displacement and voltage. An almost linear relationship exists between induced voltage and applied force. Simulation results show that PZT has demonstrated the best performance in these materials. Maximum potential voltage was shown 1.9 mV by PZT material cantilever with 29 µm displacement. Simulations can provide guidelines for designing and optimizing piezoelectric micro-cantilever pressure sensors based on comparative analysis.

  • Open access
  • 17 Reads
Hydrodynamics and gas hold-up of a gas-liquid coaxial mixing system at different scales containing a non-Newtonian fluid

The gas-liquid mixing in a mixing tank is an important process in many industrial applications, such as chemical and biochemical processing which mostly deal with the non-Newtonian fluids. The design and optimization of the aerated mixing tank with such characteristic is a challenging task. Most of these challenges are due to the non-Newtonian behavior of the fluid, which can lead to compartmentalization of the mixing tank, and formation of oxygen segregation zones. These issues become more pronounced at larger scales. These problems can be addressed by selecting the appropriate mixing equipment. The coaxial mixing systems consisting of the inner and outer impellers exhibited better performance in gas dispersion in the non-Newtonian fluids compared to that of the conventional mixing systems. Therefore, the primary objective of this study was to identify the mixing dead zones and determine their impact on the overall mixing process for the coaxial mixing system at two different scales. These dead zones are regions of low mixing intensity. Hence, this research focused on the evaluation of the hydrodynamics attained by a coaxial gas-liquid mixing tank through the numerical and experimental methods. The study was conducted using computational fluid dynamics (CFD) and electrical resistance tomography (ERT) methods. The effect of the aeration rate, inner impeller speed, and rotating mode on the creation of dead zones was investigated. The location and the size of dead zones were greatly dependent on the rotating mode and the size of the mixing vessel. Furthermore, the research outlined the relationship between the gas phase retention and the hydrodynamics of the coaxial mixing tank. This study highlights the importance of considering both the hydrodynamics and gas hold-up when designing the coaxial mixers containing a non-Newtonian fluid.

  • Open access
  • 23 Reads
Mass customized fashion in a smart, holistic wear-care business model

As the second largest consumer goods industry, the fashion industry shows high relevance in the social discourse about demand, global production routes, use and recycling of raw materials. Studies cite a shortened durability as one of the main reasons for the growing number of end-of-life garments. In order to extend the product life cycle, sustainability requires personal attachment to the fashion product, high quality of material and workmanship - In this environment, digitization can be an enabler for sustainable process design. Our research scenario uses radio frequency identification devices to digitize the service processes: With a personalized customer login the customer can get all information about the individual product development as well as possible washing and repair services. The interactive value creation results in a personal attachment. By comparing conventional life cycles with participatory service offering, we pursue the following research question: How does the life cycle of an apparel product change in a smart, holistic wear-care business model?
With mass customization users determine how their personal fashion product should be designed, which improves the fit to users' needs. In this context, digitalised participation processes (e-participation) can be used as steering instruments of sustainability dimensions. The laundry service process has already been established at the large consumer level. Textile service combines specific laundry care, repair, pick-up and delivery services. Compared to private laundry this model saves resources such as energy, water, chemicals and cares about each individual fashion item. The digital application scenario integrates these subprocesses into private use. The adaptation of established models of mass customization and laundry care in a smart, holistic wear-care business model results in eco-friendly processes of product development and use phase. Thereby material durability, awareness and emotional longevity through the strong integration of the user inside determine the new sustainable product life cycle. In this paper, we discuss a smart future scenario for the fashion industry which combines personalized product development and service-oriented laundry care through a smart, holistic process approach.

  • Open access
  • 38 Reads
Computational Approaches for Molecular Characterization and Functional Annotation of an Uncharacterized Protein of Vibrio cholerae Applying Bioinformatics Tools and Databases

When inadequate water purification and sewage disposal systems, cholera poses a significant health threat in developing nations, Vibrio cholerae (V. cholerae) is one of the mindful microscopic organisms associated with cholera illness. If cholera is not treated, renal failure, shock, hypokalemia, and pulmonary edema can occur, resulting in death in a matter of hours. The machinery of bacterial virulence factors is what causes this disease. Among the various V. cholerae strains, V. cholerae O1 is the most prevalent and pathogenic strain. The total genome succession of V. cholerae unravels the presence of different genes and uncharacterized proteins whose capabilities are not yet perceived. Therefore, it is essential to comprehend V. cholerae by analyzing the structure and annotating the function of uncharacterized proteins. The NCBI sequence of uncharacterized V. cholerae O1 EET91795.1 proteins has been annotated for this study. Domain family, protein solubility, ligand binding sites, and other parameters have all been determined using a variety of databases and computational tools. The protein's ligand-binding sites were found, and its three-dimensional structure was modeled. According to the analysis, the hotdog family protein may play metabolic roles like thioester hydrolysis in the metabolism of fatty acids and the breakdown of two products such as phenylacetic acid and the pollutant 4-chlorobenzoate. The structural prediction of this protein and detection of binding sites would suggest a potential target to uncover promising inhibitors against the protein to treat infection caused by the target strain.

  • Open access
  • 20 Reads
Identification of the process of formation of a nanocrystalline structure on the surface of Por-Si/ZnO by microscopy and electron paramagnetic resonance.
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One of the most promising processes for the formation of complex surface morphology is electrochemical anodic etching, which is used to obtain nanostructured silicon-based materials. During the process, the system of pores forms, and the material becomes heterophase, including nanocrystalline and amorphous Si, SiOx, and various functional groups that were adsorbed by the surface. Different effects and the variety of functions based on them are caused by different hierarchical levels of pores as shown by scanning electron microscopy (SEM).

The nucleation of paramagnetic centers (PMCs) on the sample surface and the formation of substance clusters from them proceeds from the initial stage of the pore formation process. While applying of an external voltage, the uniform etching of silicon and the accumulation of ions starts.

Making the surface morphology more complex by depositing thin layers of zinc oxide on porous silicon by spray pyrolysis, it was obtained a uniform distribution of ZnO nanocrystals over the surface of the sample.

The transition to the crystalline phase is associated with the formation of particles with stable bonds. With a gradual change in the power of ultrahigh-frequency radiation in the spectrum of electron paramagnetic resonance (EPR), PMCs of various structures were identified and the formation of ZnO nanocrystals based on them was shown.

According to SEM images, after deposition of ZnO layers on PorSi, the surface of the sample become more fine porous and the porosity is more homogeneous by size. The coating is localized at the pore boundaries, thus forming particles with dangling bonds.

Thus, a hierarchical surface structure, including macro and mesopores, was formed by the method of electrochemical etching. The formation of nanocrystalline structures was confirmed by the EPR method and the mechanism involving particles with uncompensated charge was proposed.

  • Open access
  • 19 Reads
Analysis of Local Shear Rate Distribution in a Double Coaxial Bioreactor containing Biopolymer Solutions using Computational Fluid Dynamics

Uniform gas dispersion and shear distribution in highly viscous non-Newtonian fluids is a challenging task due to intricate rheological behavior exhibited by this type of media. In addition, most of the large-scale bioreactors in biochemical processes such as wastewater treatment, fermentation, and pharmaceutical industries demand higher aspect ratios (i.e., fluid height to tank diameter ratio) compared to laboratory-scale bioreactors. This, in turn, underlines uneven gas and shear distribution throughout the bioreactor, especially those comprising yield-pseudoplastic fluids. For this type of fluid, there are two distinct zones within the bioreactor, a higher-shear zone with a lower apparent viscosity around the impeller and a lower-shear zone with a higher apparent viscosity away from the impeller. Due to the viscosity gradient, homogeneous gas dispersion within a single impeller aerated bioreactor with an aspect ratio more than one is hard to attain. It was established that a well-designed mixing configuration contributes to maintaining a uniform fluid viscosity, resulting in improved mixing performance and homogenous product quality. Recent studies have reported the superior performance of double coaxial bioreactors furnished with two central impellers and one anchor in terms of uniform shear distribution and gas dispersion for pseudoplastic fluids. Despite the widespread use of yield-pseudoplastic fluids in a variety of industries, however, a knowledge gap was identified for analyzing the shear distribution within the double coaxial mixers containing pseudoplastic fluids possessing yield stress. The objective of this study was to examine the effect of four coaxial mixing configurations including down-pumping and co-rotating mode, up-pumping and co-rotating mode, down-pumping and counter-rotating mode, and up-pumping and counter-rotating modes on the local shear rate distribution. In this regard, computational fluid dynamics (CFD) was employed for quantitative and qualitative evaluations of the local shear distribution within the coaxial bioreactor.

  • Open access
  • 30 Reads
Optimized Blockchain-Based Decentralized Framework for Electronic Health Records
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The medical system has been dealing with a number of difficult problems with the verification, synchronisation,sharing, and storage of electronic health information. Additionally, the random distribution of patient records offers a variety of risks to patient privacy. The problem then becomes how to distribute data safely while preserving customer privacy. Blockchain has recently been mentioned as a potential solution to enable data interchange with the protection of security and privacy because of its advantages of immutability. In this paper, a decentralised electronic medical records searchable system with performance-enhancing blockchain technology is proposed. We first perform a hash computation on the electronic medical data in order to ensure its validity and integrity, and then we store the result on the blockchain. In order to solve the scalability problem of the blockchain, the interplanetary file system, a distributed storage technology, is used to encrypt and store the encrypted electronic medical data. These steps not only address the problem of centralised data storage on the servers of multiple medical organizations, but they also assist in easing the burden of data storage and frequent access to blockchain.

This system was developed on a private blockchain network where scalability was the key bottleneck. Medical health systems currently produce a large number of records across all of their activities. All of the records are kept in this system as blockchain transactions. The data might be made accessible to all authorised users using a blockchain ledger, improving visibility and raising awareness of growth throughout the therapeutic process. To optimise the blockchain, performance bottlenecks are identified. We have performed, utilizing optimal endorsement policies and code level changes on the blockchain. The performance of the proposed network is compared with existing blockchain network with blockchain benchmarking tool. The network performance is observed to outperform by 13% and 8% when compared in terms of transaction throughput and latency, respectively, while addressing the security and trust concerns of stakeholders.

  • Open access
  • 31 Reads
Decarbonization challenges and opportunities of power sector in Uzbekistan: A simulation of Turakurgan natural gas-fired combined cycle power plant with exhaust gas recirculation

Natural gas dependency on power generation in Uzbekistan is high, with more than 85% of electricity production coming from natural gas. Hence, natural gas-fired power plants constitute the largest proportion of greenhouse gas emissions. Carbon capture, storage, and utilization (CCSU) plays an essential role in reaching Uzbekistan’s reduction targets for carbon dioxide (CO2) emissions. In this study, one (450 MW) of the two identical blocks of a 900 MW Turakurgan natural gas-fired combined cycle power plant (NGCCPP) located in the Fergana valley in Uzbekistan is simulated using Aspen Plus® commercial software and validated with its open access project data prior to the evaluation of end-of-pipe CCSU unit integration. An optimal value of exhaust gas recirculation (EGR) is identified in order to further increase the CO2 content in the flue gas while reducing the flue gas flow rate. In addition, according to the simulation results, around 2.4 Mt of annual CO2 emissions can be avoided when the capture plant is set at a 90% CO2 capture rate. Apart from that, the suitability of various CCSU integration methods such as absorption, adsorption, membrane separation, and CO2 bio-fixation is discussed considering the power plant's site-specific conditions and the obtained flue gas stream characteristics.