Journal articles on the topic 'Compressor stem'
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1
Klotz, U. E., C. Solenthaler, P. J. Uggowitzer, and M. O. Speidel. "Application of STEM-EDX Mapping for Characterizing Microstructural Instabilities En 9-12% Chromium Steels With Martensitic-Austenitic Microstructure." Microscopy and Microanalysis 6, S2 (August 2000): 354–55. http://dx.doi.org/10.1017/s1431927600034267.
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Materials for high-temperature application, e.g. in gas-turbine compressor discs or steam turbine rotors, are often susceptible to microstructural instabilities during long-term service. Such instabilities reduce the service life due to a deterioration of the mechanical properties. Therefore, it is most important to identify such instabilities, which often take place in sub-micrometer scale. A class of materials widely used in power generating industries are the martensitic 9-12% Cr steels. In the present work STEM-EDX mappings were used to reveal the distribution of alloying elements in 9-12% Cr steels with a martensitic-austenitic microstructure developed recently.The chemical composition of the material investigated was Fe-10.1Cr-6.2Co-5.2Mn-2.1Ni-1.2Mo-0.47V-0.1 IN (weight-percent). The material was subjected to a two step heat-treatment of normalizing at 1175°C for 1.5h with subsequent quenching and controlled tempering at 600°C for 20h. Due to the high amount of manganese and nickel a duplex microstructure of 30-40vol.% of austenite in a matrix of tempered martensite is formed during tempering.
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No, Albert, Mikel Hernaez, and Idoia Ochoa. "CROMqs: An infinitesimal successive refinement lossy compressor for the quality scores." Journal of Bioinformatics and Computational Biology 18, no. 06 (September 16, 2020): 2050031. http://dx.doi.org/10.1142/s0219720020500316.
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The amount of sequencing data is growing at a fast pace due to a rapid revolution in sequencing technologies. Quality scores, which indicate the reliability of each of the called nucleotides, take a significant portion of the sequencing data. In addition, quality scores are more challenging to compress than nucleotides, and they are often noisy. Hence, a natural solution to further decrease the size of the sequencing data is to apply lossy compression to the quality scores. Lossy compression may result in a loss in precision, however, it has been shown that when operating at some specific rates, lossy compression can achieve performance on variant calling similar to that achieved with the losslessly compressed data (i.e. the original data). We propose Coding with Random Orthogonal Matrices for quality scores (CROMqs), the first lossy compressor designed for the quality scores with the “infinitesimal successive refinability” property. With this property, the encoder needs to compress the data only once, at a high rate, while the decoder can decompress it iteratively. The decoder can reconstruct the set of quality scores at each step with reduced distortion each time. This characteristic is specifically useful in sequencing data compression, since the encoder does not generally know what the most appropriate rate of compression is, e.g. for not degrading variant calling accuracy. CROMqs avoids the need of having to compress the data at multiple rates, hence incurring time savings. In addition to this property, we show that CROMqs obtains a comparable rate-distortion performance to the state-of-the-art lossy compressors. Moreover, we also show that it achieves a comparable performance on variant calling to that of the lossless compressed data while achieving more than 50% reduction in size.
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Averyanov, A. V., A. G. Konoplyannikov, F. G. Zabozlaev, A. G. Sotnikova, O. V. Danilevskaya, M. A. Konoplyannikov, and A. R. Tatarsky. "Comparative study of the effects of mesenchymal stem cells with different delivery methods in an experimental model of lung fibrosis." Journal of Clinical Practice 9, no. 4 (December 15, 2018): 4–14. http://dx.doi.org/10.17816/clinpract944-14.
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Background: Transplantation of mesenchymal stem cells (MSCs) is one of the most promising directions in the treatment of idiopathic pulmonary fibrosis. In experimental small animal studies, intravenous and endobronchial (installation) techniques are used for the cell preparation delivery, while in humans inhalation of drugs is the simplest and most available method.
Aim: The aim of the study was to determine the optimal type of a nebulizer for viability of MSCs during nebulization, followed by a comparison of the effects of inhalation and intravenous delivery methods in a standard model of bleomycin pulmonary fibrosis in rabbits.
Methods: At the first stage, the survival of MSCs was assessed ex vivo after 10 minutes of compressor, ultrasound and mesh nebulization. Subsequently we used a nebulizer, which showed the best result in the cells, viability. At the next stage аfter bronchoscopic installation of bleomycin, 5 rabbits received intravenous transplantation of 2×106 allogeneic BMMSCs, other 5 rabbits — 2×107 MSCs inhaled via a compressor nebulizer; the control healthy and bleomycin groups included 5 animals each.
Results: The highest degree of viability of MSC was maintained after passing via the compressor nebulizer (72%), a significantly lower survival rate was observed in ultrasonic nebulization (20%) and no live cells were detected after mesh nebulization. Both groups treated with MSC had a significantly lower fibrosis index on the Ashcroft morphometric scale than the control group of bleomycin fibrosis. Collagen expression in the lung tissue was significantly higher in all the groups with bleomycin injury, but in animals which underwent MSC inhalation, it was significantly different (0.51 point) from the bleomycin group without treatment (2.1 points). The level of neutrophils in the BAL fluid was significantly lower in animals which received the intravenous MSC therapy. The levels of TNF-α and TGF-β1 in the BAL fluids tended to decrease in the treatment groups, but did not differ significantly from control.
Conclusions: The highest survival rate of MSCs is observed when using a compressor nebulizer, which apparently should be considered as the best way for delivering cells to the respiratory tract. Both inhalation and intravenous administration of MSCs cause similar effects of inhibiting the development of bleomycin-induced pulmonary fibrosis, which indicates the possibility of using both ways of cell delivery without loss of effectiveness.
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Kee, Benjamin L., David Curran, Huayang Zhu, Robert J. Braun, Steven C. DeCaluwe, Robert J. Kee, and Sandrine Ricote. "Thermodynamic Insights for Electrochemical Hydrogen Compression with Proton-Conducting Membranes." Membranes 9, no. 7 (July 1, 2019): 77. http://dx.doi.org/10.3390/membranes9070077.
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Membrane electrode assemblies (MEA) based on proton-conducting electrolyte membranes offer opportunities for the electrochemical compression of hydrogen. Mechanical hydrogen compression, which is more-mature technology, can suffer from low reliability, noise, and maintenance costs. Proton-conducting electrolyte membranes may be polymers (e.g., Nafion) or protonic-ceramics (e.g., yttrium-doped barium zirconates). Using a thermodynamics-based analysis, the paper explores technology implications for these two membrane types. The operating temperature has a dominant influence on the technology, with polymers needing low-temperature and protonic-ceramics needing elevated temperatures. Polymer membranes usually require pure hydrogen feed streams, but can compress H 2 efficiently. Reactors based on protonic-ceramics can effectively integrate steam reforming, hydrogen separation, and electrochemical compression. However, because of the high temperature (e.g., 600 ° C) needed to enable viable proton conductivity, the efficiency of protonic-ceramic compression is significantly lower than that of polymer-membrane compression. The thermodynamics analysis suggests significant benefits associated with systems that combine protonic-ceramic reactors to reform fuels and deliver lightly compressed H 2 (e.g., 5 bar) to an electrochemical compressor using a polymer electrolyte to compress to very high pressure.
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ARIFFIN, SITI HAJAR, KONSTANTINOS GKATZIONIS, and SERAFIM BAKALIS. "EFFECT OF COMPRESSION ON MECHANICAL PROPERTIES OF READY-TO-EAT (RTE) SPINACH VARIETIES." Malaysian Applied Biology 49, no. 3 (October 25, 2020): 107–15. http://dx.doi.org/10.55230/mabjournal.v49i3.1553.
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Compression-induced injury is frequently encountered during handling, packaging, transporting, and storage. In this study, compression test was performed using a mechanical tester, Universal Testing Machine Z030 (Zwick/Roell, Germany). Spinach varieties (Teen, Organic, Salad, and Baby) were used to study the response of spinach varieties towards stress. For single loading/unloading compression, maximum work (MaxW) and area under the curve (AUC) required to compress Organic spinach were found to be the highest followed by Teen and Salad spinach. The MaxW and AUC were found to be decreasing after storage which showed that the total work generated to compress the leaves was reduced due to texture degradation of the product after storage. For multiple loading/unloading compression, as the number of compressions increased, the MaxW decreased. Similar trend was observed at day 6. Apart from that, the MaxW for all the three spinach types were found to be similar at the 5th compression. This shows that regardless of the spinach types, they reached maximum resistance towards stress after the 5th consecutive compression. Under 200 N compression, leaves with stem required higher energy to compress compared to leaves without stem. However, for leaves compressed under 50 N and 100 N, the difference was only noticed on the 1st compression. The MaxW was found to be similar for leaves with stem and without stem starting from the 2nd compression till the 5th compression. The irregular and larger cell size of Organic spinach as compared to round-shaped and smaller cell size of Teen and Salad spinach may contribute to the ability of the Organic spinach tissue to have higher resistance towards mechanical stress during compression.
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Kalashnikov, Dmitriy, Yuriy Borisov, and Elizaveta Kalashnikova. "Natural gas intracyclic attachment for energy generating unit based on gas turbine plant." E3S Web of Conferences 114 (2019): 06004. http://dx.doi.org/10.1051/e3sconf/201911406004.
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In this article, problems of effectiveness increasing in complex power supply are considered. Disadvantages of centralized power engineering and advantages of power engineering capabilities organization in immediate consumer proximity are presented. Consumer needs satisfaction in electricity, heat supply and cold supply are offered to be realized by conversion of district and quarter boiler houses to trigeneration stations, which are based on gas turbine plants units. In this research, solutions of problem related to lack of fuel gas pressure for gas turbine engine power, which is included in gas turbine plant of trigeneration stations, are suggested. As a result, after considering possible variants of fuel gas pressure increasing, it was decided that there is a perspective of using fuel gas intracyclic compression attachment. Its operating principle involves organization of main steam extraction in heat cycle for booster compressor drive, which compresses fuel gas before its transfer to combustor of gas turbine plant. Results of gas compressor and drive steam turbine design are presented. These parts are included in fuel gas intracyclic compression attachment in specific unit of gas turbine plant. Also, general recommendations about new compressor and turbine stages design for any other units of gas turbine plant are pointed. Further, in the article, two variants of thermal circuit, based on gas turbine plant, are suggested. The first one is a circuit with hot water boiler, where exhaust gas recuperation after turbine is carried out for producing steam, related to fuel gas intracyclic compression attachment demands, and heat system water heating for consumer heat supply system. The second variant involves development of typical gas turbine plant unit in power station with exhaust boiler. There fuel gas intracyclic compression attachment is activated by steam work after exhaust boiler. Then, variants of diagram are compared between each other. Also advantages and disadvantages each of them are considered.
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Sukhomlinov, Igor, and Mihail Golovin. "Expedited method of testing and refinement of refrigeration centrifugal compressors." E3S Web of Conferences 140 (2019): 06004. http://dx.doi.org/10.1051/e3sconf/201914006004.
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Currently existing regulatory documents assume that refrigeration compressors are tested as part of test rigs with heat-exchange equipment. Given the high energy intensity of centrifugal compressors, the drive power of which in cooling mode with a cold capacity of up to 8.0 MW can be 2.0 or more MW, the creation of test rigs for preliminary and acceptance tests at the manufacturer’s factory requires a large investment. An alternative to the considered refrigeration centrifugal compressors test method is a test on a test rig in which the agent is partially condensed. In this case, an evaporator and a full-sized condenser are not required. The mathematical model of the refrigeration centrifugal compressors developed by JSC VNIIKHOLODMASH, allows testing of the refrigeration centrifugal compressors in model conditions, when the entire compressor operation cycle at the test rig is carried out in the area of superheated steam. Since the refrigeration centrifugal compressors mathematical model is based on physical simulation of compression processes in model stages at different values of conditional Mach numbers, dimensionless characteristics of model stages can be used to calculate the characteristic of the created compressor when operating under new conditions. The implementation of the model test method provides reduction of testing time due to absence of phase changes of the agent, improves the accuracy of the obtained results, reduces of power consumption, simplifies the test rig, and reduces consumption of the agent for filling the rig and water for cooling the agent.
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Vlăducă, Iulian, Ramona Stanciuc, Răzvan Bimbaşa, and Sorin Gabriel Tomescu. "Waste-Energy (Heat) Recovery System from the Gases Compressed by an Oil-Free Screw Compressor." E3S Web of Conferences 112 (2019): 01012. http://dx.doi.org/10.1051/e3sconf/201911201012.
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During compression, a gas heats up, almost in all cases this heat being wasted, either by cooling the gas because it is too hot for the application, or by storing the gas and letting the compressed gas cool naturally in the storage tank. This paper presents a waste-energy (heat) recovery system from the gases compressed by an oil-free screw compressor. The gases compressed by this compressor have a very high temperature compared to an oil injected screw compressor, due to the fact that the oil used to lubricate the rotors also acts as a heat sink, the oil free variant which is used when you want a very high purity of the gas, has higher tolerances and more friction between the rotors which result in a higher gas temperature. The recovery system uses a heat exchanger to extract the waste energy from the gas and at the same time it will cool it for immediate use. Depending on the requirements, the energy recovered may be used immediately to produce useful work or stored for a later use. It may be used for heating a building, to produce steam for a turbine driving electrical generator, or in other forms.
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Klimenko, A. V., V. S. Agababov, A. V. Koryagin, S. N. Petin, and P. N. Borisova. "USE OF EXPANDER-GENERATOR UNIT AT CHP OF METALLURGICAL PLANT FOR PRODUCING ELECTRIC POWER AND INCREASING EFFICIENCY OF COMPRESSOR." Izvestiya. Ferrous Metallurgy 62, no. 9 (October 23, 2019): 698–704. http://dx.doi.org/10.17073/0368-0797-2019-9-698-704.
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The ability of saving energy in the production of compressed air is one of the most energy-consuming production in which much of the used energy is lost. The proposed technical solution is based on the united use of two energy-saving technologies. The first of them is the use of technological pressure drop of transported natural gas which lost irrevocably when it is throttled at gas control stations. The second one is air cooling before the compressor sections to reduce compression work. A scheme of a combined steam blowing and heat power plant of a metal manufacturer is proposed. In addition to a power and heat generating turbine and a two-section air compressor with a steamturbine drive, a two-stage expander-generator unit (EGU) producing electricity and cold is used. The thermodynamics of gas expansion processes in the expander is considered, the choice of a two-stage scheme is founded. The cold produced in the EGU is used to lower the air temperature at the inlet to the first and second sections of the compressor, thus reducing fuel consumption for air compression. Using the proposed scheme allows to reduce fuel consumption to the compressor drive, to use the heat of compressed air to preheat the transported gas before the steps of the expander and to generate additional electric power. At the same time, fuel is not used to generate electricity, and the heat of the cooled air is not discharged into the environment, therefore the plant operation is characterized by high environmental performance. The procedure for calculating of fuel economy when using the proposed scheme is given. The assessment has shown that the use of this scheme allows, under given conditions of calculation, to reduce fuel consumption at the combined heat power and steam blowing plant by 11.2 thousand tons of fuel equivalent per year, which is 0.84 %. The generated electric power of the EGU will be 5.3 MW.
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Prokopov, M., S. Sharapov, Yu Merzlyakov, and D. Gusev. "The energy efficiency concept and implementation prospects of the jet thermocompression principle in small heat energy." Energy and automation, no. 2(54) (June 22, 2021): 39–51. http://dx.doi.org/10.31548/energiya2021.02.039.
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The expediency of the implementation of the principle of steam thermal compression to improve the energy efficiency of sources of electricity and heat supply of small heat power engineering is substantiated. The results of thermodynamic analysis and numerical optimization of the parameters of the compressor steam-turbine cycle of a small cogeneration power plant are presented. A jet step-down thermotransformer has been tested - as an alternative to traditional boiler heating. On the basis of the conducted thermodynamic analysis, a new combined cycle of a step-down thermotransformer has been developed, which ensures efficient conversion of the supplied energy (mainly in the form of fuel heat) into the heat carrier flow of the heat supply system with the required temperature level 50 ... 90 °C). The fundamental difference between the considered thermal transformer and steam compressor heat pumps is the replacement of a mechanical compressor with a steam thermocompressor module (STC-unit). The working process in the STK-module is realized by using the liquid phase of the refrigerant, which boils up during expiration, subcooled to saturation, as an active medium of a jet compressor. Injection of steam from the evaporator is provided due to the fine-dispersed vapor-droplet structure formed in the outlet section of the active flow nozzle. A program for the numerical study of the working process of a step-down thermal transformer was prepared and tested, on the basis of which multivariate calculations were carried out. On the basis of computational studies, the area of achievable indicators of the proposed heat supply system has been established; the area of initial operating parameters corresponding to the maximum values of the conversion coefficient and exergy efficiency was determined; comparative indicators of the main parameters of the investigated thermal transformer on various working substances in the range of operating modes as a heat pump or a refrigerating machine were obtained. Key words: workflow, steam thermocompressor, step-down thermotransformer, energy efficiency, heat pump mode
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Camp, T. R. "A Study of Acoustic Resonance in a Low-Speed Multistage Compressor." Journal of Turbomachinery 121, no. 1 (January 1, 1999): 36–43. http://dx.doi.org/10.1115/1.2841232.
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Measurements are presented of a resonant acoustic phenomenon occurring in a low-speed multistage compressor. The results show that this phenomenon shares many characteristics with acoustic resonance as measured in high-speed compressors. These similarities include a rotating pressure field, several acoustic frequencies corresponding to different circumferential modes, step changes in frequency as the flow rate is increased, and acoustic frequencies that are independent of flow coefficient, shaft speed, and the axial length of the compression system. The paper includes measurements of the helical structure of the rotating pressure field and of the variation in amplitude of the acoustic signal over a stator exit plane.
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Lucas, Radika, Andy Jones, Wesley Ford, and Matt Doyle. "The effective use of data analytics in an advanced compressor performance and degradation monitoring system." APPEA Journal 58, no. 2 (2018): 723. http://dx.doi.org/10.1071/aj17086.
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Origin is the upstream operator and joint venture partner in Australia Pacific LNG. Origin’s integrated gas operations require reliable, sustainable delivery of gas to the downstream LNG facility on Curtis Island. This scale of operation requires establishing a ‘single source of truth’ regarding compressor condition and performance while achieving maximum and reliable compression capacities. Therefore, capability of monitoring performance of centrifugal compressors across the fleet is considered an essential component of production surveillance. Xodus leveraged Origin’s OSIsoft PI AF (PI Historian Asset Framework) tool. This system was used to build a compressor performance and degradation monitoring tool to accurately identify early indications of degradation in a multi-stage centrifugal compression train. The tool utilises live data from the PI historian to calculate key performance indicators which define compressor and driver operation. Dimensionless parameter analysis allows Origin to accurately quantify performance degradation regardless of variations in plant inlet conditions at each gas processing facility. Deviation from baseline performance in dimensionless parameters such as polytropic efficiency, work input number and polytropic head coefficient is used to quantify capacity losses, additional power consumption and increase in suction pressure. The tool provided the ability to use performance indicators to confidently determine the mode and extent of compressor degradation and prevent accelerated fouling which can lead to premature bundle changes. Also, this information helps streamline and has led to a major step change for the decision-making process concerning maximum production from rotating equipment. Additionally, this allowed operations to be confident on the condition of the compressor bundle, continue operation with higher capacities during high demand periods and ensure compressor bundle changeout is optimised for availability and economic aspects.
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Parulekar, Prashant S., Richard Hudson, and Harrison Boyd. "Significant reliability improvements in reciprocating gas compressor packages at Arrow Energy." APPEA Journal 58, no. 1 (2018): 168. http://dx.doi.org/10.1071/aj17046.
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Arrow Energy operates a fleet of four-stage reciprocating compressors in the Surat Basin, boosting low-pressure coal-seam gas (at 60 kPag) to transmission pipeline pressure (in excess of 9000 kPag). Historically, the compressors and the gas engine drivers exhibited persistent problems associated with high vibrations, inadequate engine and process gas cooling, poor compressor valve reliability and premature engine component failures. Hot Queensland summer conditions further exacerbated these problems, which resulted in frequent unit trips during hot periods when gas and electricity prices demanded consistent gas production at nameplate capacity. Since 2014, Arrow Energy has carried out systematic analytical studies to establish the compressor package component limitations and develop technical solutions to address these. Stub shaft-driven air coolers, compressor valves, gas engine heads and valves, compressor frame and crosshead mounting arrangements were some of the key components studied in detail. Utilising systematically designed field tests with laboratory calibrated test instruments, scale model laboratory tests, advanced computer simulations, data analytics and new technology trials, several key design modifications were implemented. The outcome of these design changes has enabled Arrow Energy to achieve a step-change in reliability for the better, with each reciprocating compression package (including gas engine driver) operating in excess of 98% reliability. The implemented changes were executed at minimal cost and resulted in significant reduction in maintenance costs. The increased reliability and consistent production during the peak summer hours easily justified the modifications made to the packages. This paper describes the technical work undertaken, changes implemented and their outcomes.
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Arsenyev, Vyacheslav, Victor Kozin, Iurii Merzliakov, and Mikhail Protsenko. "Jet Thermal Compression of the Ammonia-Water Mixture for Heat Pumps and Refrigerating Systems." Applied Mechanics and Materials 630 (September 2014): 61–65. http://dx.doi.org/10.4028/www.scientific.net/amm.630.61.
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The potential and features of thermotransformer operation has been investigated with the employment of jet thermal compression in heat pump or refrigeration cycles. Jet thermal principle is realized by means of injection and compression of the low-pressure steam with the help of working steam jet. It is formed with the help of relaxation vaporization of the subcooled liquid inside motive flow duct of jet compressor instead of the conventional mechanical compressor. It is a part of the jet thermal compression module which includes a liquid-vapor jet compressor, a separator, a pump and a heater. Perspective of application the ammonia-water mixture as working substance is determined by its high thermodynamic and environmental properties, possibility to maintain higher condensation temperatures than when using CFC, HCFC and HFC chemicals.
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Betelmal, E. H., and S. A. Farhat. "Energy and Exergy Analysis of a Simple Gas Turbine Cycle with Wet Compression." Mechanical Engineering Research 8, no. 1 (April 3, 2018): 30. http://dx.doi.org/10.5539/mer.v8n1p30.
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A thermodynamic model of the wet compressor in a simple gas turbine cycle was investigated in this paper. A suitable quantity of water was injected into the compressor-stages where it evaporated. Subsequently, the steam and air were heated in the combustion chamber and expanded in the turbine. The wet compressor (WC) has become a reliable way to reduce gas emissions and increase gas turbine efficiency. In this study, the operational data of the simple gas turbine and the maximum amount of water that can be injected into the compressor were assessed, as well as a comparison between the dry compression, the wet compression and the isentropic compression. The performance variation due to water spray in the compressor and the effect of varying ambient temperature on the performance of gas turbine (thermal efficiency, power) was investigated, and the results are compared to the results of the same cycle with a dry compressor. The analytical formula of exergy destruction and results show that exergy destruction increases with water injection. The programming of the performance model for the gas turbine was developed utilizing the software IPSEpro. The results of the gas turbine with a wet compressor demonstrates a 12% reduction in the compressor exit temperature up to isentropic temperature. The compressor work decreased by 11% when using a wet compressor, this lead to an improvement in power output and efficiency However, the wet compressor increases the specific fuel consumption and heat rate of the gas turbine. There are limitations in the amount of steam that can be injected, 0.4 kg/s of water was the optimum amount injected into the compressor.
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Averyanov, A. V., A. G. Konoplyannikov, F. G. Zabozlaev, O. V. Danilevskaya, M. A. Konoplyannikov, A. V. Sorokina, I. A. Koroleva, et al. "Effects of inhalation and intravenous administration of allogeneic mesenchymal bone marrow stromal cells in a bleomycin-induced model of pulmonary fibrosis in rabbits." Russian Journal of Transplantology and Artificial Organs 19, no. 4 (January 30, 2018): 88–96. http://dx.doi.org/10.15825/1995-1191-2017-4-88-96.
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Aim:to perform a comparative analysis of the effi cacy of the inhaled and intravenous delivery of equivalent doses of bone marrow mesenchymal stem cells (BMMSCs) in rabbits according to the standard model of bleomycin pulmonary fi brosis.Materials and methods.After bronchoscopic instillation of bleomycin, 5 rabbits received intravenous transplantation of 2 × 106 allogeneic BMMSCs, other 5 rabbits – 2 × 107 MSCs inhaled via compressor nebulizer; control healthy and bleomycin group included 5 animals each.Results.Both groups treated with BMMSCs had a signifi cantly lower Ashcroft fi brosis index than the bleomycin control group. Expression of collagen in lung tissue in all groups with bleomycin injury was superior to healthy controls, but in animals underwent intravenous BMMSC transplantation collagen score was 0.74 points, and in inhaled treated group – 0.51 points, while in bleomycin controls – 2.1 point. Levels of TNF-α and TGF-β1 in BAL fl uids tended to decrease in treatment groups, but did not differ signifi cantly from control. A similar picture was observed in the cytological analysis of BAL.Conclusion.In general, both methods of delivering of BMMSCs to the lungs demonstrated similar therapeutic effects in inhibiting the development of experimental fi brosis, indicating that both intravenous and inhalational way of introduction can be used for subsequent clinical studies.
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La Grassa, Riccardo, Cristina Re, Gabriele Cremonese, and Ignazio Gallo. "Hyperspectral Data Compression Using Fully Convolutional Autoencoder." Remote Sensing 14, no. 10 (May 20, 2022): 2472. http://dx.doi.org/10.3390/rs14102472.
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In space science and satellite imagery, better resolution of the data information obtained makes images clearer and interpretation more accurate. However, the huge data volume gained by the complex on-board satellite instruments becomes a problem that needs to be managed carefully. To reduce the data volume to be stored and transmitted on-ground, the signals received should be compressed, allowing a good original source representation in the reconstruction step. Image compression covers a key role in space science and satellite imagery and, recently, deep learning models have achieved remarkable results in computer vision. In this paper, we propose a spectral signals compressor network based on deep convolutional autoencoder (SSCNet) and we conduct experiments over multi/hyperspectral and RGB datasets reporting improvements over all baselines used as benchmarks and than the JPEG family algorithm. Experimental results demonstrate the effectiveness in the compression ratio and spectral signal reconstruction and the robustness with a data type greater than 8 bits, clearly exhibiting better results using the PSNR, SSIM, and MS-SSIM evaluation criteria.
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Ritzberger, Daniel, Christoph Hametner, and Stefan Jakubek. "A Real-Time Dynamic Fuel Cell System Simulation for Model-Based Diagnostics and Control: Validation on Real Driving Data." Energies 13, no. 12 (June 17, 2020): 3148. http://dx.doi.org/10.3390/en13123148.
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Fuel cell systems are regarded as a promising candidate in replacing the internal combustion engine as a renewable and emission free alternative in automotive applications. However, the operation of a fuel cell stack fulfilling transient power-demands poses significant challenges. Efficiency is to be maximized while adhering to critical constraints, avoiding adverse operational conditions (fuel starvation, membrane flooding or drying, etc.) and mitigating degradation as to increase the life-time of the stack. Owing to this complexity, advanced model-based diagnostic and control methods are increasingly investigated. In this work, a real time stack model is presented and its experimental parameterization is discussed. Furthermore, the stack model is integrated in a system simulation, where the compressor dynamics, the feedback controls for the hydrogen injection and back-pressure valve actuation, and the purging strategy are considered. The resulting system simulation, driven by the set-point values of the operating strategy is evaluated and validated on experimental data obtained from a fuel cell vehicle during on-road operation. It will be shown how the internal states of the fuel cell simulation evolve during the transient operation of the fuel cell vehicle. The measurement data, for which this analysis is conducted, stem from a fuel cell research and demonstrator vehicle, developed by a consortium of several academic and industrial partners under the lead of AVL List GmbH.
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Kusbandono, Wibowo. "The Effect of Water Impact on the Refrigerant Pipeline between Compressor and Condensor on COP and Efficiency of Cooling Machine." International Journal of Applied Sciences and Smart Technologies 3, no. 2 (December 31, 2021): 203–14. http://dx.doi.org/10.24071/ijasst.v3i2.3822.
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The purpose of this research is (a) to design and assemble a steam compression cycle cooling machine using the main components on the market (b) to obtain the characteristics of the cooling engine, which includes the Coefficient of Performance (COP) and the efficiency of the cooling engine. The research was conducted experimentally in the laboratory. The refrigeration machine works by using a steam compression cycle, with the main components: a compressor, an evaporator, a capillary tube and a condenser. The compressor power is 1/6 PK, while the other main components are adjusted to the size of the compressor power. The refrigerant used is R134a. Variations of the research were carried out on the condition of the refrigerant pipe located between the compressor and condenser: (a) without being submerged in water (b) submerged in 0.50 liters of water and (c) submerged in 0.75 liters of water. The results of the study provide information that the water immersion in the refrigerant pipe which is located between the compressor and condenser affects the COP value and the efficiency of the refrigeration machine. Consecutively (1) without being submerged in water, the COP value is 2.45 and the efficiency is 0.64 (2) submerged in liter of water, the COP value is 2.41 and the efficiency is 0.62 (3) submerged in liter of water, the value COP is 2.34 and efficiency is 0.60.
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Sadvakasov, D. Kh, G. I. Chernov, and V. L. Yusha. "The analysis of uncertainty factors influence on mathematical modeling of ammonia compression in wet vapor area." Omsk Scientific Bulletin. Series Aviation-Rocket and Power Engineering 5, no. 3 (2021): 30–38. http://dx.doi.org/10.25206/2588-0373-2021-5-3-30-38.
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The paper presents the influence analysis of such uncertainty factors as the heat transfer coefficient calculation method and the working chamber wall temperature on the mathematical modeling of the ammonia compression in a reciprocating compressor stage during the condensation of ammonia vapors. The mathematical model is based on the equation of the first law of thermodynamics for bodies with variable mass, the equation of state for real gases, the Clausius–Clapeyron and Newton–Richman equations. When determining the heat transfer coefficient value, several well-known dependencies for calculating these coefficients for dropwise and filmwise condensation have been considered. The calculation data shows that the instantaneous values of the ammonia pressure and temperature, as well as of the dryness fraction during compression in the wet steam region, significantly depends on the chosen method for calculating the heat transfer coefficient. Moreover, the walls temperature value of the compressor working chamber, where the compression occurs, has a considerable impact on the process under discussion. They are the determining factors and require special attention when the ammonia compression process is mathematically modelled in a reciprocating compressor stage, taking into account its vapors condensation.
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Yoshihara, Hiroshi, and Kyohei Nobusue. "Mode I and Mode II fracture toughness of densified Sitka spruce fabricated in an airtight atmosphere with high-temperature steam." Holzforschung 62, no. 1 (January 1, 2008): 82–85. http://dx.doi.org/10.1515/hf.2008.012.
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Abstract Mode I and Mode II initiation fracture toughness was examined by DCB (double cantilever beam) and 3ENF (three-point bend end notched flexure) tests on specimens of compressed Sitka spruce. The compressed wood was fabricated by varying the compression ratio, and the effectiveness of the compression treatment was examined in view of improving the fracture mechanics properties. In both cases, the fracture toughness did not show a significant increase after the compression treatment. Thus, it would be necessary to develop a new compression treatment method to improve the fracture mechanics properties.
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HISHIKI, Tsubasa, Shuhei NAKAMURA, Toshiyuki HINO, and Yoshiharu AMANO. "B213 Experiment and analysis of two-phase compression in a steam compressor." Proceedings of the National Symposium on Power and Energy Systems 2013.18 (2013): 267–70. http://dx.doi.org/10.1299/jsmepes.2013.18.267.
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Kurauchi, S. K., and J. R. Barbosa. "DESIGN OF A CENTRIFUGAL COMPRESSOR FOR NATURAL GAS." Revista de Engenharia Térmica 12, no. 2 (December 31, 2013): 40. http://dx.doi.org/10.5380/reterm.v12i2.62043.
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This work presents the design of a centrifugal compressor for natural gas in three steps. The first step is the 1-D preliminary design heavily based on empirical data, only the design point was considered here. The second step is the flow analysis in the meridional plane. The last step is the CFD analysis to verify if the 1-D design methodology is adequate. The CFD simulations showed good agreement with the results obtained in the preliminary design, proving the importance of empirical data in the design of centrifugal compressors.
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Valenti, Gianluca, Stefano Murgia, Ida Costanzo, Matteo Scarnera, and Francesco Battistella. "Experimental Determination of the Performances during the Cold Start-Up of an Air Compressor Unit for Electric and Electrified Heavy-Duty Vehicles." Energies 14, no. 12 (June 19, 2021): 3664. http://dx.doi.org/10.3390/en14123664.
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Compressed air is crucial on an electric or electrified heavy-duty vehicle. The objective of this work was to experimentally determine the performance parameters of the first prototype of an electric-driven sliding-vane air compressor, specifically designed for electric and electrified heavy-duty vehicles, during the transient conditions of cold start-ups. The transient was analyzed for different thermostatic temperatures: 0 °C, −10 °C, −20 °C, and −30 °C. The air compressor unit was placed in a climatic chamber and connected to the electric grid, the water-cooling loop, and the compressed air measuring and controlling rig. The required start-up time was greater the lower the thermostatic temperature, ranging from 30 min at 0 °C to 221 min at −30 °C and depending largely on the volume of the lubricant oil filled initially. The volume flow rate of the compressed air was lower than nominal at the beginning, but it showed a step increase well beyond nominal when the oil reached 50 °C and then decreased gently towards nominal, while the input power kept steady at nominal after a short initial peak. These facts must be considered when estimating the time and the energy required by the air compressor unit to fill up the compressed air tanks of the vehicles.
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Khalaf, Walaa, Ahmad Saeed Mohammad, and Dhafer Zaghar. "Chimera: A New Efficient Transform for High Quality Lossy Image Compression." Symmetry 12, no. 3 (March 3, 2020): 378. http://dx.doi.org/10.3390/sym12030378.
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A novel scheme is presented for image compression using a compatible form called Chimera. This form represents a new transformation for the image pixels. The compression methods generally look for image division to obtain small parts of an image called blocks. These blocks contain limited predicted patterns such as flat area, simple slope, and single edge inside images. The block content of these images represent a special form of data which be reformed using simple masks to obtain a compressed representation. The compression representation is different according to the type of transform function which represents the preprocessing operation prior the coding step. The cost of any image transformation is represented by two main parameters which are the size of compressed block and the error in reconstructed block. Our proposed Chimera Transform (CT) shows a robustness against other transform such as Discrete Cosine Transform (DCT), Wavelet Transform (WT) and Karhunen-Loeve Transform (KLT). The suggested approach is designed to compress a specific data type which are the images, and this represents the first powerful characteristic of this transform. Additionally, the reconstructed image using Chimera transform has a small size with low error which could be considered as the second characteristic of the suggested approach. Our results show a Peak Signal to Noise Ratio (PSNR) enhancement of 2.0272 for DCT, 1.179 for WT and 4.301 for KLT. In addition, a Structural Similarity Index Measure (SSIM) enhancement of 0.1108 for DCT, 0.051 for WT and 0.175 for KLT.
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Hussien, Marwa Kamel, and Hameed Abdul-Kareem Younis. "DWT Based-Video Compression Using (4SS) Matching Algorithm." Journal of University of Human Development 1, no. 4 (September 30, 2015): 427. http://dx.doi.org/10.21928/juhd.v1n4y2015.pp427-432.
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Currently, multimedia technology is widely used. Using the video encoding compression technology can save storage space, and also can improve the transmission efficiency of network communications. In video compression methods, the first frame of video is independently compressed as a still image, this is called intra coded frame. The remaining successive frames are compressed by estimating the disparity between two adjacent frames, which is called inter coded frame. In this paper, Discrete Wavelet Transform (DWT) is used powerful tool in video compression. Our coder achieves a good trade-off between compression ratio and quality of the reconstructed video.
The motion estimation and compensation, which is an essential part in the compression, is based on segment movements. The disparity between each two frames was estimated by Four Step Search (4SS) Algorithm. The result of the Motion Vector (MV) was encoded into a bit stream by Huffman encoding while the remaining part is compressed like the compression was used in intra frame. Experimental results showed good results in terms of Peak Signal-to-Noise Ratio (PSNR), Compression Ratio (CR), and processing time.
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Chekh, O., S. Sharapov, and V. Arsenyev. "Adiabated flowing streams in nozzles: influence of regular characteristics on relaxation steam formation." Refrigeration Engineering and Technology 55, no. 1 (February 10, 2019): 10–14. http://dx.doi.org/10.15673/ret.v55i1.1347.
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Two-phase nozzles, in which the phase transition process takes place, can work in jet superchargers for various purposes, including jet thermal pumps (steam-water injectors) and thermal compressors. In such schemes of thermal transformers, the ejector performs the function of a preliminary compression stage in order to reduce the load on the compression of the working substance in the main compressor. The use of fluxes of boiling liquid as energy-efficient working fluids is inhibited due to the lack of a reliable description of the mechanism of their flow. Finding the dependence of the steam content on the pressure and temperature at the nozzle exit will make it possible to determine the variant of the initial parameters at which the overproduction of steam will be greatest. It is also worth determining the change in the velocity factor, as well as the change in the thrust of the nozzle in the studied range of parameters, in order to find out whether the pressure at the nozzle outlet is a determining factor when choosing the design parameters of the nozzles. The article proposes to investigate the boiling streams in such nozzles by the method of mathematical modeling using a model that takes into account the relaxation nature of vaporization. The study used a compressible two-phase medium model, a kinetic model of evaporation / condensation. The model also takes into account the dynamic and mechanical equilibrium of the process of evaporation-condensation. The calculations were performed using an Ansys CFX commercial CFD product. The value of the mean square relative error of pressure measurement does not exceed 0,119%. The average discrepancy between the obtained data between the mathematical model and the field experiment does not exceed 3%.
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CUI, HAO-LEI, and HUI-SHEN SHEN. "MODELING AND SIMULATION OF BUCKLING AND POSTBUCKLING OF PLANT STEMS UNDER COMBINED LOADING CONDITIONS." International Journal of Applied Mechanics 03, no. 01 (March 2011): 119–30. http://dx.doi.org/10.1142/s1758825111000907.
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Numerical simulations for local buckling and postbuckling behavior of plant stems are presented under two combined loading cases: (1) axial compression (caused by axial grains) combined with wind pressure; and (2) bending moment (caused by eccentric axial grains) combined with wind pressure. Based on its microstructure, a hollow plant stem is modeled as a stringer stiffened multiwalled shell. The material properties of the stem are assumed to be orthotropic. The nonlinear governing equations for buckling and postbuckling of plant stems are solved through arc-length method along with Newton–Raphson technique. The numerical calculations are carried out using the finite element package ABAQUS. The results show that the postbuckling equilibrium path is unstable for plant stems subjected to axial compression or bending combined with relatively low values of wind pressure. Large reduction in buckling load and in postbuckling strength can be found even if the applied wind pressure is relatively small, which results in the easy occurrence of stem lodging.
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M, Lakshminarayana, and Mrinal Sarvagya. "MICCS: A Novel Framework for Medical Image Compression Using Compressive Sensing." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 5 (October 1, 2018): 2818. http://dx.doi.org/10.11591/ijece.v8i5.pp2818-2828.
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The vision of some particular applications such as robot-guided remote surgery where the image of a patient body will need to be captured by the smart visual sensor and to be sent on a real-time basis through a network of high bandwidth but yet limited. The particular problem considered for the study is to develop a mechanism of a hybrid approach of compression where the Region-of-Interest (ROI) should be compressed with lossless compression techniques and Non-ROI should be compressed with Compressive Sensing (CS) techniques. So the challenge is gaining equal image quality for both ROI and Non-ROI while overcoming optimized dimension reduction by sparsity into Non-ROI. It is essential to retain acceptable visual quality to Non-ROI compressed region to obtain a better reconstructed image. This step could bridge the trade-off between image quality and traffic load. The study outcomes were compared with traditional hybrid compression methods to find that proposed method achieves better compression performance as compared to conventional hybrid compression techniques on the performances parameters e.g. PSNR, MSE, and Compression Ratio.
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SCHMIDT-SCHAUß, MANFRED. "Linear pattern matching of compressed terms and polynomial rewriting." Mathematical Structures in Computer Science 28, no. 8 (August 2, 2018): 1415–50. http://dx.doi.org/10.1017/s0960129518000208.
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We consider term rewriting under sharing in the form of compression by singleton tree grammars (STG), which is more general than the term dags. Algorithms for the subtasks of rewriting are analysed: finding a redex for rewriting by locating a position for a match, performing a rewrite step by constructing the compressed result and executing a sequence of rewrite steps. The first main result is that locating a match of a linear termsin another termtcan be performed in polynomial time ifs,tare both STG-compressed. This generalizes results on matching of STG-compressed terms, matching of straight-line-program-compressed strings with character-variables, where every variable occurs at most once, and on fully compressed matching of strings. Also, for the case wheresis directed-acyclic-graph (DAG)-compressed, it is shown that submatching can be performed in polynomial time. The general case of compressed submatching can be computed in non-deterministic polynomial time, and an algorithm is described that may be exponential in the worst case, its complexity isnO(k), wherekis the number of variables with double occurrences insandnis the size of the input. The second main result is that in case there is an oracle for the redex position, a sequence ofmparallel or single-step rewriting steps under STG-compression can be performed in polynomial time. This generalizes results on DAG-compressed rewriting sequences. Combining these results implies that for an STG-compressed term rewrite system with left-linear rules,mparallel or single-step term rewrite steps can be performed in polynomial time in the input sizenandm.
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Li, Xiangjun, Fuhao You, Qing Lu, Haoguang Zhang, and Wuli Chu. "The Investigation of a New End Wall Contouring Method for Axial Compressors." Applied Sciences 12, no. 10 (May 10, 2022): 4828. http://dx.doi.org/10.3390/app12104828.
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To further control corner separation in high-load axial compressors, this study proposes a new end wall contouring method. It defines multiple standard “surface units” with particular flow control effects and then applies a linear combination, finally forming the geometry of the end wall surface. Based on design experiences, three different end wall contouring cases are generated and calculated on a high-load compressor cascade in the first step. The results show that the new method achieves a clear and intuitive influence on the end wall geometry, with a proper number of design variables, and can effectively combine variables with the development of secondary flow. In the second step, the new method was applied to an axial compressor, with an improvement in the design variables. Although the end wall contouring only improved the efficiency of the compressor stage on the right part of its operating map, the experimental results of the flow field show that the corner separation and end wall loss are suppressed at multiple inflow conditions. The results thus verified the practical effect of the newly developed end wall contouring method.
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Patil, Sandesh. "Lifting of Water at Remote Places using Steam and Compressed Air." International Journal for Research in Applied Science and Engineering Technology 9, no. VI (June 20, 2021): 1924–34. http://dx.doi.org/10.22214/ijraset.2021.35384.
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Lifting of water at remote places using steam and compressed air .the objectives of this unit is to pump water at remote places. In this project we use turbocharger (turbine& compressor), furnace, water pump, IBR valves and mechanical hardware equipment’s. The main objective is pump water at places where the electricity is not available or available at high cost with the help of steam and compressed air which help to rotate turbine and pump. It can also use to generate electricity at remote places by assembling electrical generator. This thesis also takes into consideration the material used with minimum possible cost. The design of project is such that it can easily dissemble and assemble and easy to operate.
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Zhang, Hao, Ze Meng Zhao, Ahmet Palazoglu, and Wei Sun. "Ozone Prediction Performance of HMM Based on the Data Compressed by Different Wavelet Basis Functions." Advanced Materials Research 518-523 (May 2012): 1586–91. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.1586.
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Surface ozone in the air boundary layer is one of the most harmful air pollutants produced by photochemical reaction between nitrogen oxides and volatile hydrocarbons, which causes great damage to human beings and environment. The prediction of surface ozone levels plays an important role in the control and the reduction of air pollutants. As model-driven statistical prediction models, hidden Markov Models (HMMs) are rich in mathematical structure and work well in many important applications. Due to the complex structure of HMM, long observation sequences would increase computational load by geometric ratio. In order to reduce training time, wavelet decomposition is used to compress the original observations into shorter ones. During compression step, observation sequences compressed by different wavelet basis functions keep different information content. This may have impact on prediction results. In this paper, ozone prediction performance of HMM based on different wavelet basis functions are discussed. Shannon entropy is employed to measure how much information content is kept in the new sequence compared to the original one. Data from Houston Metropolitan Area, TX are used in this paper. Results show that wavelet basis functions used in data compression step can affect the HMM model performance significantly. The new sequence with the maximum Shannon entropy generates the best prediction result.
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Li, Fangfang, Vladimir Lukin, Oleg Ieremeiev, and Krzysztof Okarma. "Quality Control for the BPG Lossy Compression of Three-Channel Remote Sensing Images." Remote Sensing 14, no. 8 (April 10, 2022): 1824. http://dx.doi.org/10.3390/rs14081824.
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This paper deals with providing the desired quality in the Better Portable Graphics (BPG)-based lossy compression of color and three-channel remote sensing (RS) images. Quality is described by the Mean Deviation Similarity Index (MDSI), which is proven to be one of the best metrics for characterizing compressed image quality due to its high conventional and rank-order correlation with the Mean Opinion Score (MOS) values. The MDSI properties are studied and three main areas of interest are determined. It is shown that quite different quality and compression ratios (CR) can be observed for the same values of the quality parameter Q that controls compression, depending on the compressed image complexity. To provide the desired quality, a modified two-step procedure is proposed and tested. It has a preliminary stage carried out offline (in advance). At this stage, an average rate-distortion curve (MDSI on Q) is obtained and it is available until the moment when a given image has to be compressed. Then, in the first step, an image is compressed using the starting Q determined from the average rate-distortion curve for the desired MDSI. After this, the image is decompressed and the produced MDSI is calculated. In the second step, if necessary, the parameter Q is corrected using the average rate-distortion curve, and the image is compressed with the corrected Q. Such a procedure allows a decrease in the MDSI variance by around one order after two steps compared to variance after the first step. This is important for the MDSI of approximately 0.2–0.25 corresponding to the distortion invisibility threshold. The BPG performance comparison to some other coders is performed and examples of its application to real-life RS images are presented.
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HISHIKI, Tsubasa, Shuhei NAKAMURA, Yoshiharu AMANO, and Toshiyuki HINO. "Experiment and Analysis of Two-Phase Compression in a Rocking Type Steam Compressor." TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B 79, no. 808 (2013): 2826–35. http://dx.doi.org/10.1299/kikaib.79.2826.
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HUYNH, THANH NGOC, TOẢN QUỐC TRẦN, and QUYẾT THÀNH PHẠM. "Research on aerodynamic characteristics through airflow clearances in compressor blades of gas turbine engine." Science & Technology Development Journal - Engineering and Technology 3, SI3 (December 27, 2020): first. http://dx.doi.org/10.32508/stdjet.v3isi3.640.
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Reducing the loss in the airflow clearance among the compressor blades of the rotor disk and stationary blades (guide vanes) is an urgent issue. Furthermore, additional losses of airflow through the clearances among the blades and airfoil losses are the main cause of reducing the efficiency of an axial flow compressor, especially the blade height is small. With a view towards the efficiency improvement of a multistage axial compressor with a high-pressure ratio, it is necessary to manufacture a highly economical compressor with a variety of compression stages. Airflow in the circulation clearances alternating among compressor blades has viscosity, unstable compression, and quite complex flow structure. This needs to be researched into the design with the assistance of modern software (ANSYS CFX, FlowER, etc.). Although this is an important step in the current design orientation, it requires additional practical elements to perform, especially the problem of optimizing the outer rim, the level, and the number of compression stages in the whole compressor. In this paper, authors have used the method of creating three-dimensional (3D) models for blade profiles in a compressor based on analyzing the flow in three-dimensional form and studying their parameters. This paper deals with the geometry problems of the row of rotating blades (cascade) by proposing the structural arrangement of stacking blades in the circular direction and the blade profile formed the S-shape. Investigating and calculating the aerodynamic properties of the airflow through clearances of compressor blades by using ANSYS is one of the new methods. The researched result showed the dependence between the camber angle as the rotating blade formed an S-shape profile rotates regarding the stagger angle of the airfoil and the incident angle of airflow. Some characteristics of aerodynamic properties are distributed according to the blade height in conducting with different curved profiles of the rotating blades on the rotor disk and stationary blades.
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Fredericksen, T. S., R. L. Hedden, and S. A. Williams. "Effect of stem bending on hydraulic conductivity and wood strength of loblolly pine." Canadian Journal of Forest Research 24, no. 3 (March 1, 1994): 442–46. http://dx.doi.org/10.1139/x94-060.
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Stems of 30-year-old loblolly pine (Pinustaeda L.) trees were bent with a winch to determine the effect of bending, which might occur from severe wind stress, on the hydraulic conductivity and wood strength of tree stems. Stems were bent to a point of imminent stem failure and then released. After release, stems leaned an average of 6.25° from their original vertical position. Measurements of sapwood permeability and viable conducting area were made on stem sections cut from bent trees and were compared with sections taken from unstressed (control) trees. Dye was used to determine the percentage of functional conducting elements. An average loss of approximately 30% in conducting sapwood area was attributed to the bending treatment. Loss of functional conducting area was greater along the axis of bending than on the lateral sides of the stem perpendicular to the direction of bending. Damage was greatest on the compression side of the stem. Despite this damage, no difference was observed in sapwood permeability due to treatment. Modulus of elasticity and modulus of rupture were reduced by 19% and 34%, respectively, on the compression side of bent stems compared with control stems. Loblolly pine appears to be capable of sustaining significant damage to its water conducting system without compromising its hydraulic conductivity. However, reduced wood strength due to bending may result in increased susceptibility to wind breakage and (or) decreased commercial value.
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Rechter, H., W. Steinert, and K. Lehmann. "Comparison of Controlled Diffusion Airfoils With Conventional NACA 65 Airfoils Developed for Stator Blade Application in a Multistage Axial Compressor." Journal of Engineering for Gas Turbines and Power 107, no. 2 (April 1, 1985): 494–98. http://dx.doi.org/10.1115/1.3239758.
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In their transonic cascade wind tunnel, DFVLR has done measurements on a conventional NACA 65, as well as on a controlled diffusion airfoil, designed for the same velocity triangle at supercritical inlet condition. These tested cascades represent the first stator hub section of a three-stage axial/one-stage radial combined compressor developed by MTU with the financial aid of the German Ministry of Research and Technology. One aspect of this project was the verification of the controlled diffusion concept for axial compressor blade design, in order to demonstrate the capabilities of some recent research results which are now available for industrial application. The stator blades of the axial compressor section were first designed using NACA 65 airfoils. In the second step, the controlled diffusion technique was applied for building a new stator set. Both stator configurations were tested in the MTU compressor test facility. Cascade and compressor tests revealed the superiority of the controlled diffusion airfoils for axial compressors. In comparison to the conventional NACA blades, the new blades obtained a higher efficiency. Furthermore, a closer matching of the compressor performance data to the design requirements was possible due to a more precise prediction of the turning angle.
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Younis, Hameed, Abdulkareem Abdalla, and Turki Abdalla. "Partial Encryption of Compressed Image Using Threshold Quantization and AES Cipher." Iraqi Journal for Electrical and Electronic Engineering 8, no. 8 (June 1, 2012): 1–11. http://dx.doi.org/10.37917/ijeee.8.1.1.
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Cryptography is one of the technological means to provide security to data being transmitted on information and communication systems. When it is necessary to securely transmit data in limited bandwidth, both compression and encryption must be performed. Researchers have combined compression and encryption together to reduce the overall processing time. In this paper, new partial encryption schemes are proposed to encrypt only part of the compressed image. Soft and hard threshold compression methods are used in the compression step and the Advanced Encryption Standard (AES) cipher is used for the encryption step. The effect of different threshold values on the performance of the proposed schemes are studied. The proposed partial encryption schemes are fast, secure, and do not reduce the compression performance of the underlying selected compression methods.
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Amori, Dr Karima E., Dr Mohammad N. Hussain, Zainab T. Abdulwahab, and Wafa O. Ali. "Utilizing OF Thermal Energy OF Gas Turbines Exhaust Gases Working IN Petroleum Sector." Journal of Petroleum Research and Studies 7, no. 2 (May 6, 2021): 190–210. http://dx.doi.org/10.52716/jprs.v7i2.196.
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The gas turbine stations are used in petroleum sector for different application, such as compressing of gas, pumping of crude oil or water, and power generation. The main parts of these stations are compressor, combustion chamber, and gas turbine. The compressor provides a compressed air for combustion process, and for cooling process of different parts of the station. The fuel (liquid or gas fuel) is injected into the combustion chamber to perform the combustion process. The resulted hot flue gases are passed to the gas turbine to convert its' thermal energy into rotational mechanical energy to operate the air and gas compressors, crude oil or water pumps, and to generate electricity.This work concerns with the applicability of utilizing the thermal energy content in flue gases exit from the gas turbine by adopting a field data received from one of the operating stations in north Oil Company in Iraq. The flue gases mass flow rate, and its' available energy have been calculated. Different operational conditions have been selected to produce superheated steam such as operating pressure range of (0.36-1.4 MPa), with a range of superheated temperature differs than the corresponding saturation temperature by (10-60 oC) for each selected pressure. This work is also concerned with the possibility of producing of hot water for a pressure range of (0.36-1.4 MPa) with a temperature lower than the corresponding saturation temperature by (5 oC). The results show that the power produced reaches (1.4-3.3 MW). Also the hot water produced reaches 90000 kg/hr at operating pressure of 0.36MPa.
The obtained results in this work are interesting since an elimination of thermal pollution by exhaust gases is accomplished. The available energy in these gases has been utilized to produce either superheated steam or hot water without consuming a conventional fuel.ntroductionI -
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Worden, Natalie J., Kristian J. Ash, Nathaniel R. Ordway, Mark A. Miller, Kenneth A. Mann, Gretchen M. VanDeventer, Dominick M. Valenzano, Robert Hart, Mitsunori Kayano, and Kei Hayashi. "Radiographic and Biomechanical Assessment of Three Implant Designs for Canine Cementless Total Hip Replacement." Veterinary and Comparative Orthopaedics and Traumatology 33, no. 06 (September 24, 2020): 417–27. http://dx.doi.org/10.1055/s-0040-1715476.
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Abstract Objective The aim of this study was to evaluate the relationship between radiographic fit/fill measurements and biomechanical performance of three canine cementless total hip implant designs using an in vitro biomechanical testing protocol that replicates compression and torsion. Study Design Eighteen (six/group) canine cadaveric femurs were implanted with one of three cementless total hip implant designs: (1) collarless, (2) collared or (3) lateral bolt stems. Femoral length, canal flare index (CFI), canal fill, stem fit, stem level and stem angle were measured as independent variables. Biomechanical performance was tested using physiological, non-destructive gait loading (loading protocols) and destructive testing (failure protocols). Results During loading protocols, compressive stiffness was influenced by stem level (p < 0.05) and torsional stiffness was influenced by stem level and CFI for collarless stems (p < 0.05). During failure protocols, peak load was influenced by mediolateral (ML) stem angle (p < 0.05) and CFI (p < 0.01) for collarless stems and CFI for lateral bolt stems (p < 0.05). Peak torque was influenced by ML stem angle, craniocaudal stem angle and CFI for collarless stems (p < 0.05) and average ML fill for collared stems (p < 0.05). Conclusion Biomechanical performance of collarless stems in cementless hip arthroplasty is more impacted by radiographic fit/fill than lateral bolt and collared stems. As a result, collarless stems may be more dependent on preoperative fit and intraoperative precision.
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Berndsen, Rodrigo Strzelecki, Ricardo Jorge Klitzke, Djeison Cesar Batista, Eduardo Mauro do Nascimento, and Fabiano Ostapiv. "RESISTÊNCIA À FLEXÃO ESTÁTICA E À COMPRESSÃO PARALELA DO BAMBU-MOSSÔ (Phyllostachys pubescens)." FLORESTA 43, no. 3 (September 13, 2013): 485. http://dx.doi.org/10.5380/rf.v43i3.29319.
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O objetivo deste estudo foi analisar o efeito da posição do colmo e da idade nas propriedades mecânicas de flexão estática e compressão paralela às fibras do bambu-mossô (Phyllostachys pubescens), correlacionando a densidade aparente com as propriedades avaliadas. Os corpos de prova utilizados nos ensaios foram produzidos de material laminado colado, adaptados segundo a norma para madeira sólida ASTM D143-96, seguindo as proporções mantidas por Ahmad (2000). Os resultados apresentaram tendência crescente da resistência na flexão estática com a idade e com a posição do colmo em termos absolutos. Para os ensaios de compressão paralela às fibras, a resistência à compressão (fc) e o MOE tiveram a mesma tendência de aumento da resistência com a idade e com a posição. Os ensaios demonstraram estatisticamente que não houve efeito significativo da interação entre a idade e a posição do colmo. A densidade aparente apresentou uma correlação linear e positiva no teste de flexão estática quanto aos valores do MOR e do MOE, assim como no teste de compressão paralela às fibras para a resistência à compressão (fc) e para o MOE. Baixos coeficientes de correlação foram obtidos entre a densidade aparente e as propriedades mecânicas estudadas.AbstractCompressive strength and flexure of Moso bamboo (Phyllostachys pubescens). The aim of this study was to determine the mechanical properties of bending and compression parallel to grain of Moso bamboo (Phyllostachys pubescens) and analyze the effect of stem position and age on these properties. It was also studied the correlation between the bulk density and mechanical properties. The tests used specimens produced in glued laminated material, adapted according to ASTM D143 solid wood-96 norm, following proportions maintained by Ahmad (2000). The results revealed increasing trend of resistance in bending with age and stem position in absolute terms. In relation to compression tests parallel to grain, the compression strength (fc) and the MOE had the same tendency to increase resistance with age and with the position. The tests revealed that there was no statistically significant interaction between age and culm position. The apparent density of bamboo revealed a positive and linear correlation in bending test at MOR and MOE, as well as at parallel compression test to the fibers for the compression force (fc) and the MOE. Low correlation coefficients had been obtained between the focused apparent density and mechanical properties.Keywords: Mechanical properties; age; position of the culm.
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Kim, Kyoung Hoon, Dong Joo Kim, Kyoung Jin Kim, and Seong Wook Hong. "An Assessment of Wet Compression Process in Gas Turbine Systems with an Analytical Modeling." Applied Mechanics and Materials 234 (November 2012): 23–27. http://dx.doi.org/10.4028/www.scientific.net/amm.234.23.
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Recently humidified gas turbine systems in which water or steam is injected have attracted much attention, since they can offer a high efficiency and a high specific power with a relatively low cost compared to combined-cycle gas turbine systems, and therefore they have a potential for future power generation. In this study, performance analysis of the wet compression process is carried out with an analytical modeling which was developed from heat and mass transfer, and thermodynamic analyses based on droplet evaporation. Wet compression variables such as temperature-averaged polytropic coefficient, compressor outlet temperature, and compression work are estimated. Parametric studies show the effect of system parameters such as droplet size, water injection ratio or compression ratio on transient behavior.
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Hussien, Marwah K. "Encryption of Stereo Images after Compression by Advanced Encryption Standard (AES)." Al-Mustansiriyah Journal of Science 28, no. 2 (April 11, 2018): 156. http://dx.doi.org/10.23851/mjs.v28i2.511.
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New partial encryption schemes are proposed, in which a secure encryption algorithm is used to encrypt only part of the compressed data. Partial encryption applied after application of image compression algorithm. Only 0.0244%-25% of the original data isencrypted for two pairs of dif-ferent grayscale imageswiththe size (256 ´ 256) pixels. As a result, we see a significant reduction of time in the stage of encryption and decryption. In the compression step, the Orthogonal Search Algorithm (OSA) for motion estimation (the dif-ferent between stereo images) is used. The resulting disparity vector and the remaining image were compressed by Discrete Cosine Transform (DCT), Quantization and arithmetic encoding. The image compressed was encrypted by Advanced Encryption Standard (AES). The images were then decoded and were compared with the original images. Experimental results showed good results in terms of Peak Signal-to-Noise Ratio (PSNR), Com-pression Ratio (CR) and processing time. The proposed partial encryption schemes are fast, se-cure and do not reduce the compression performance of the underlying selected compression methods
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Selimefendigil, Fatih, and HakanF Oztop. "Exergetic performance of VCR system with TiO2-nano additive in the compressor oil." Thermal Science, no. 00 (2020): 58. http://dx.doi.org/10.2298/tsci190731058s.
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Exergy analysis of a vapor-compression refrigeration system with TiO2 nanoadditives in the compressor oil was performed. Two-step method was used for the preparation of nano-oil for various solid particle volume fractions between 0% and 1%. Irreversibilities were determined by using second law of thermodynamics. Reduction in total irreversibility is achieved with nanoparticle inclusion and it was significant for higher particle volume fraction.
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Dong, Yuhang, and W. David Pan. "Image Classification in JPEG Compression Domain for Malaria Infection Detection." Journal of Imaging 8, no. 5 (May 3, 2022): 129. http://dx.doi.org/10.3390/jimaging8050129.
Full textAbstract:
Digital images are usually stored in compressed format. However, image classification typically takes decompressed images as inputs rather than compressed images. Therefore, performing image classification directly in the compression domain will eliminate the need for decompression, thus increasing efficiency and decreasing costs. However, there has been very sparse work on image classification in the compression domain. In this paper, we studied the feasibility of classifying images in their JPEG compression domain. We analyzed the underlying mechanisms of JPEG as an example and conducted classification on data from different stages during the compression. The images we used were malaria-infected red blood cells and normal cells. The training data include multiple combinations of DCT coefficients, DC values in both decimal and binary forms, the “scan” segment in both binary and decimal form, and the variable length of the entire bitstream. The result shows that LSTM can successfully classify the image in its compressed form, with accuracies around 80%. If using only coded DC values, we can achieve accuracies higher than 90%. This indicates that images from different classes can still be well separated in their JPEG compressed format. Our simulations demonstrate that the proposed compression domain-processing method can reduce the input data, and eliminate the image decompression step, thereby achieving significant savings on memory and computation time.
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Lachenbruch, Barbara, Fernando Droppelmann, Claudio Balocchi, Miguel Peredo, and Erika Perez. "Stem form and compression wood formation in young Pinus radiata trees." Canadian Journal of Forest Research 40, no. 1 (January 2010): 26–36. http://dx.doi.org/10.1139/x09-169.
Full textAbstract:
The crooked stems of some individuals of radiata pine ( Pinus radiata D. Don) can hinder volume recovery and wood quality. To infer causes of crookedness and to learn how lean angle affects compression wood (CW) formation we studied 5-year-old trees in southern Chile. Eight initially straight and eight initially crooked trees were tethered initially to angles of 15° or 30° or were left untethered for 131 days (48 trees total). There were no significant differences between straight and crooked trees in the extent of CW in pretreatment wood or in the relationship between stem angle and CW extent. Crooked trees, however, righted themselves more quickly than did straight trees at angles <15°, a result that supports the overcompensation hypothesis for the development of crooked stems. Stem angle had a complex effect on CW extent. In 2- to 3-year-old wood there was no meaningful effect of angle on CW extent. One-year-old wood produced less CW at stem angles <10° than at stem angles >10°, but above or below that threshold, there was no meaningful effect of angle on CW extent. The intertree differences in CW extent, as well as the correlation of leader CW extent with bole CW in the best individuals, suggests that CW assays could be used for early screening for wood quality.
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Yamamoto, F., T. T. Kozlowski, and K. E. Wolter. "Effect of flooding on growth, stem anatomy, and ethylene production of Pinushalepensis seedlings." Canadian Journal of Forest Research 17, no. 1 (January 1, 1987): 69–79. http://dx.doi.org/10.1139/x87-013.
Full textAbstract:
Flooding of soil for 43 days greatly altered growth and stem anatomy and increased ethylene production by stems of 10-month-old Pinushalepensis seedlings. Flooding reduced the dry weight increment of seedlings primarily as a result of decay of roots and, to a lesser extent, inhibition of growth of roots and needles. Flooding did not influence height growth of seedlings but increased stem diameter, largely because of an increase in bark thickness at all stem heights and stem hypertrophy associated with proliferation of phloem parenchyma cells and an increased amount of intercellular space in the phloem. The effects of flooding on xylem increment varied appreciably with stem height. In the submerged portion of the stem, flooding greatly reduced the number of tracheids laid down per radial file. Flooding also slightly reduced the number of tracheids produced in the portion of the stem just above the water level. In the upper stem, however, flooding had little effect on xylem increment and on tracheid production for the first 29 days but increased both thereafter. Flooding also induced formation of short, thick-walled, rounded tracheids resembling those in compression wood. However, these tracheids developed an S3 wall layer, which is absent in well-developed compression wood. Flooding also increased the number of longitudinal resin ducts as well as the number and size of the xylem rays. The basic density of stem segments was lower in flooded than in unflooded seedlings, largely because of the high proportion of parenchyma cells and more intercellular spaces in the wood and bark of flooded seedlings. Flooding greatly increased production of 1-amino-cyclopropane-1-carboxylic acid by roots and ethylene by stems. The capacity for production of ethylene increased faster in stem segments just above the water line than in submerged portions of stems. However, the capacity for ethylene production as a flooding response declined progressively with increase in stem height above the basal whorl of branches. The data indicated an important regulatory role of ethylene in altering growth and stem anatomy of woody plants.
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Kravchenko, Volodymyr, Sergiy Surkov, and Hussam Ghanem. "Modelling and optimization of seawater desalination process using mechanical steam compression." Odes’kyi Politechnichnyi Universytet. Pratsi, no. 2 (August 20, 2016): 31–35. http://dx.doi.org/10.15276/opu.2.49.2016.08.
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Reichert, W. M., C. J. Bruckner, and Sui-Ren Wan. "Fiber Optic Sensing of Fluorescent Emission from Compressed Cyanine-Dye-Impregnated Fatty Acid Monolayers at the Air/Water Interface." Applied Spectroscopy 42, no. 4 (May 1988): 605–8. http://dx.doi.org/10.1366/0003702884429292.
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Fluorescence was collected from cyanine-dye-impregnated arachidic acid monolayers at the air/water interface with the use of a fiber optics configuration and a Langmuir film balance. Fatty-acid-to-dye molar ratios in the monolayers ranged from 99:1 to 1:1. The monolayers were compressed in a step-wise manner, with sampling of cyanine fluorescence after each compression step. A drop in fluorescence intensity ranging from 20 to 80% was observed between the uncompressed and compressed monolayers. The observed fluorescence decrease appeared to be a function of barrier pressure rather than molecular area and dye concentration.