Formation Of Mixture Research Articles

The effect of some vegetable origin oils used in different clove varieties against Meloidogyne incognita

Alternative control methods are needed against plant parasitic nematodes in Gerbera (Gerbera jamesonii L.) and Carnation (Dianthus caryophyllus L.) plants and one of these methods is the use of plant-based extracts against nematodes. Plant parasitic nematodes cause economic damage in cut flower production areas, so in order to reduce this damage, it is aimed to use different non-synthetic plant-based extracts as an alternative to chemical control methods within the scope of cultural control of nematodes. For this purpose, garlic, thyme, and terminator (70% thyme + 30% different plant mixture formation) were used to determine the resistance against M. incognita in two different clove cultivars, Turbo with standard flower type and Harnet with spray flower type. While the egg pack index was 1.40 ± 0.70 in the Harnet cultivar with garlic application, this rate was 16.00 ± 9.66 in the positive control. While the egg pack index was 1.20 ± 0.42 in the Turbo variety, in which garlic was applied, this value was 3.70 ± 0.48 in the control. When evaluated based on varieties, the egg package index was lower in the Turbo variety with garlic application compared to the Harnet variety.

MODELING OF MIXTURE FORMATION IN A TWO-STROKE DIESEL ENGINE

The Ukrainian engine industry played a significant role in the creation, production, and improvement of the efficiency of two-stroke diesel engines with opposed mooved pistons and providing them with the highest indicators of liter and overall power. The results of research carried out at the department of engines and hybrid power plants of NTU "KhPI" reveal existing reserves for further improvement, ensuring world-class indicators and forming promising characteristics of two-stroke diesel engines of the 6DN12/2x12 series. Further developments to ensure a new level of power cannot be implemented exclusively by updating auxiliary units and systems. To create a promising power plant, the problem must be considered in a complex with an understanding of the physical and chemical processes in the engine cylinder. The two-stroke cycle and design features limit the possibilities of conducting experimental studies of engines of this type, and make it necessary to determine reserves for increasing their efficiency. In this case, the dissemination of ideas about the course of mixture formation processes in a two-stroke engine with lateral fuel injection becomes an urgent scientific and practical task. Solving this problem makes it possible to determine the reserves of increasing combustion efficiency in engines with reciprocating movement of pistons. Based on the results of the research, a mathematical model is proposed that allows us to determine the most rational ways of organizing mixture formation, provided the conditions of uniform distribution of fuel in the volume of the combustion chamber are ensured. The obtained results of the calculated studies are the basis for the development of structural elements, further experimental studies and the implementation of measures to ensure the further improvement of the mixing efficiency of two-stroke diesel engines of the 6DN12/2x12 series and their modifications.

SELECTION OF GAS MIXER PARAMETERS FOR DIESEL CONVERSION GENERATOR MOTOR IN GAS DIESEL

According to literary sources, options for converting diesel engines into dual-fuel engines for operation on any fuel, in particular, natural gas (NG), were analyzed. The conversion method with external mixture formation and an ignition dose of liquid fuel involves the preparation of a gas-air mixture of the required composition in a special device. The methodology for choosing the design parameters of the gas mixer for the organization of the work process of a V-shaped diesel engine type 12Ch 15/17.5, converted into a gas diesel, which works as part of a motor-generator unit of backup power supply, is given. The basic design of the diesel motor-generator was analyzed. A comparative calculation of the working processes of diesel and gas-diesel variants of execution (with an ignition dose of diesel fuel of 10%) was carried out. The requirements for the design and location of the gas mixer have been formed. In the work, using 3D modeling technologies, the geometry of the gas mixer and its flow part were formed. Using the method of finite volumes, the calculation grid was synthesized and its adaptation near solid walls was carried out. Next, a series of numerical experiments was conducted in a three-dimensional setting to evaluate the throughput and quality of mixing network methane with air (when the robot is operating at typical operating modes). The distribution of flow velocities in the vertical and horizontal planes of the flow part of the gas mixer was evaluated, the change in pressure along the height of the gas mixer and the distribution of the mass fraction of methane in the flow part of the engine intake tract were analyzed, and scientific and practical recommendations were developed to ensure the efficient operation of gas diesel as part of a motor-generator installation. It is shown that the proposed design of the gas mixer allows effective mixing of methane with air when operating in the entire power range of the considered engine. The use of 3D modeling technologies, with the use of modern numerical methods, allows you to assess the operating conditions of the mixture by macro indicators and in local sub-regions, which allows, in the future, to develop recommendations for increasing the efficiency of the process of preparing the fuel-air mixture.

CRITERIA FOR ASSESSING THE EFFECTIVENESS OF TRANSPORT POWER PLANTS DECARBONISATION IN ACCORDANCE WITH IMPLEMENTATION OF THE SUSTAINABLE DEVELOPMENT CONCEPT

The directions of restoration and further development of the energy sector in Ukraine are considered in accordance with power plants with internal combustion engines, taking into account the widespread implementation of the Sustainable Development concept, which allows solving existing modern social, economic and environmental problems. For Ukraine, taking into account the economic opportunities and selected priorities for the chosen path of development, it is necessary at this time to choose gradual and specific directions to implement the Sustainable Development concept. The most priority areas of practical implementation of the concept are determined and it is indicated that the effectiveness of this implementation is associated with the development of the industry on the basis of the fourth and fifth industrial revolutions (Industry 4.0 and Industry 5.0). One of the main tasks in solving the problems of the concept is to ensure the environmental component. Notwithstanding the noted progress in improving the environmental efficiency of internal combustion engines, further attention needs to be paid to the task of spreading the introduction of “green energy”, i.e. decarbonisation – reducing greenhouse gas emissions into the environment (CO2). The issue of decarbonisation in the future should be given the greatest attention both in the development and in the manufacture and operation of engines. It is shown that the assessment of the impact of CO2 emitted with the exhaust gases of internal combustion engines into the environment is carried out taking into account the model of operation of engines and the justification of the introduced adjustments. A new criterion is proposed, which is called: “ICE criterion of environmental thermal pollution”, which is proposed for use in studies to assess the effectiveness of the implementation of decarbonisation strategies in all modes of transport at implementation of the Sustainable Development concept in global transport power plants. A method for determining the efficiency of physical and chemical processes of mixture formation and combustion in internal combustion engine cylinders is proposed when using hybrid fuel with “green hydrogen” as its component, which allows determining the dependence of hydrogen influence on the level of engines effective performance and formation of harmful emissions in exhaust gases.

Multiscale simulation of spray and mixture formation for a coaxial atomizer

Coaxial atomization is an established atomization strategy for many stationary combustion systems. While modeling spray formation in coaxial atomization is challenging due to the existence of a wide range of length and time scales, typical models introduce a substantial uncertainty for Euler–Lagrange simulations of the actual application, e.g., a spray flame. To reduce uncertainties, a recently proposed multiscale approach is adopted for simulations of realistic applications in this work. The multiscale approach uses three one-way coupled simulation domainss that cover the internal nozzle flow, the interfacial flow of the near-field, and the dispersed flow of the far-field. The capabilities of the approach are explored by applying it to a standardized non-reacting experiment from the flame spray pyrolysis research community. In order to assess the relevance for application simulations, results are discussed in the context of mixture formation. The results are compared against shadowgraphy images of the near-field and measured droplet statistics in the far-field. It is found that the multiscale approach is capable of providing similarly accurate droplet statistics as experiments or models derived from them. In addition, it is found that the breakup dynamics in the near-field introduce substantial mixture fraction fluctuations. These fluctuations are only included because of the deterministic coupling of the multiscale approach and are typically neglected in conventional approaches.

Insights into chemical aging of urban aerosols over Delhi, India

Atmospheric particles can undergo aging as they are transported over long distances and mix with particles from other sources. This can lead to the accumulation of pollutants and the formation of complex aerosol mixtures with diverse chemical and physical properties. To investigate the process of aging in ambient atmosphere, 24h sampling of PM2.5 aerosol particles on Quartz microfiber filter with a tin substrate was carried out from November 2020 to March 2021 at CSIR-National Physical Laboratory, New Delhi (28°38'10″ N and 77°10′17" E), using fine particle sampler. Based on the observations of weather and meteorological parameters, a few episodic cases have been selected, and samples were analyzed at bulk and individual particle level. The objective of the present study is to investigate the aging characteristics of aerosols, enabling us to understand the mixing of aerosols (at both bulk and individual particle levels) and the variation in fresh and deformed (aged with other species) graphitic content in the episodic cases. The Raman Spectroscopy technique employed measures the intensity of graphitic (G band; around 1580 cm−1) and disordered graphitic (D band; around 1320 cm−1) content of aerosols. Individual particle microscopic observations reveal the occurrence of open chain fractals of black carbon in variable monomer sizes, sometimes agglomerated with metals like Cu, Cr, Ca etc., along with the presence of S- rich and organic aerosols while the Raman Spectrum (bulk sample analysis) highlights graphitic and disordered (when graphite interacts with other chemical species) graphitic intensities. Comparing the intensities of heavy haze and moderate haze with non-haze days (for comparison purpose, March 23, 2021 with the lowest PM2.5 concentration ∼ 62 μg/m3, has been considered as a non-haze day), it was observed that the intensities recorded on haze days were 45 to 200 times higher for the G band and 43 to 93 times higher for the D band; while for moderate haze days, the intensities were 4 to 61 times higher for the G band and 2 to 29 times higher for the D band. These findings suggest chemical processing of BC during haze days.

Study of the diesel fuel drop vaporization and combustion at a hydrogen-diesel fuel dual fuelled diesel engine

Abstract The present paper shows the analysis of the results of the theoretical model developed by authors for diesel fuel drops vaporization study, air-diesel fuel-hydrogen mixture forming estimation and diesel fuel drops combustion in the presence of air-hydrogen mixtures set in the cylinder before the start of conventional fuel injection. The model is applied to a single cylinder diesel engine fuelled with diesel fuel and hydrogen, in dual mode by diesel gas method, at the engine speed of 900 rev/min. For a diesel fuel drop the vaporization speed, mixture formation speed, combustion speed, flame radius are presented and analysed. At hydrogen use, the cyclic amount of diesel fuel is reduced and the vaporization duration of the diesel fuel drop is reduced comparative to classic fuelling. At dual fuelling, the combustion of the burning of air-hydrogen mixtures in the vicinity of diesel droplets leads to reduced vaporization time, with 43%, an increased vaporization rate, with 26.9% and an accelerated formation of the mixture between diesel fuel and air-hydrogen mixture. Further, the combustion speed increase with 6.9%, the combustion time is decreased with 6% and the flame radius increase with 6.7%.

Applying the SeDeM Expert Diagram System for Characterization of Multiple Component Powder Mixtures for Fixed-dose Combination Matrix-type Tablet Formulations

Background: The SeDeM Expert Diagram System (SeDeM EDS) is an innovative formulation tool that provides an index of compressibility, which can be used to predict a pow-der’s suitability for direct compression to produce acceptable tablets. Objective: This study investigated the application of this tool to evaluate multiple component powder formulation mixtures for direct compression of tablets. The SeDeM EDS was specifically used to characterize powder mixtures for fixed-dose combination (FDC) matrix-type tablets that contained multiple active ingredients, which has not been done previously with SeDeM EDS. Methods: The FDC matrix-type tablets contained diclofenac sodium and vitamins B1, B6 and B12 in fixed ratios, intended for the management of peripheral neuropathy. The parameters of the SeDeM EDS were determined for the multiple-component powder mixtures and the indices were calculated to predict direct compressibility. The FDC tablets were subsequently manufactured uti-lizing direct compression and subjected to pharmacotechnical test evaluations to measure the ac-curacy of the SeDeM EDS’s predictions. Results: This study proved the versatility of the SeDeM EDS and its utility to adequately charac-terize FDC powder mixtures for matrix-type tablets manufactured by direct compression. Addi-tionally, a new calculation was suggested to determine the percentage of corrective excipients re-quired in the case when multiple incidence factor values are below the value of 5. Prediction of the correct quantity of corrective excipient to be added is important to obtain an acceptable direct compressible formulation. Conclusion: The results obtained confirmed that the SeDeM EDS correctly predicted the performance of all formulations.

Simulation study on preventing explosive mixture formation in PEM electrolysers’ water recovery tanks

Investigations of safety issues related to the design and operation of high-pressure proton exchange membrane (PEM) water electrolysers have until now mainly focused on the electrolyser stack. The present study focuses on the risk of explosive mixture formation in the water recovery system, which is part of the balance of plant in water electrolysers. After a major electrolyser company experienced an unexpected detonation in their system, we analysed their process design as a base case: a low-pressure buffer tank where anodic and cathodic water is mixed with make-up deionised water poses a safety risk because an explosive gas mixture is likely to form there, resulting in severe accidents. Several retrofit options are explored using dynamic and steady-state simulation models: these options are then evaluated based on their effects on safety, general economics and operation of the plant, in addition to ease of retrofit. The results show that preventing the formation of explosive gas mixtures in the water recovery system is achievable in several ways, such as avoiding recycling cathodic water altogether, stripping it of hydrogen, flushing buffer tanks with nitrogen or oxygen, rearranging the balance of plant appropriately, or changing the control algorithms of the system.

Evaluation of the ducted fuel injection concept for medium duty engines and multi-hole nozzles: An optical analysis

Ducted Fuel Injection (DFI) is a strategy still in development, which has proved to be effective in reducing soot emissions in compression ignition engines. It works by driving the spray, formed by a high-pressure fuel injection, through a small duct co-axial to the spray itself, which is expected to affect the mixture formation and combustion process, in turn leading to noticeable reduction in soot formation. This strategy has been mostly deployed in spray vessels or in some cases in heavy duty engines consisting of mostly 2-to-4-hole nozzle injectors. For this reason, the work here is aimed to study the potential of DFI in a medium-duty single-cylinder optical engine fueled with conventional diesel having an 8-hole nozzle injector. Two different optical techniques including OH* chemiluminescence and 2-color pyrometry have been utilized to perform the analysis regarding combustion evolution and soot formation. A parametric analysis regarding different geometrical parameters including stand-off distance, diameter and length of duct has been carried out regarding the DFI performance. Results indicate that DFI does decrease the soot emissions in the context of this study and the duct geometrical parameters influence combustion evolution and soot formation ultimately affecting the device's performance. However, the scale of soot reduction is not as high as reported in previous studies, which is limited by specific boundary conditions including combustion chamber design, piston geometry utilized in this study.

Correlations between sewage sludge composting physicochemical parameters and emissions of greenhouse gases and ammonia: A statistical analysis

Mitigating the environmental impact of composting by the reduction of greenhouse gases (N2O, CH4) and ammonia (NH3) emissions is a major challenge. To meet this challenge, the understanding of the relationships between composted substrates initial physicochemical parameters and gas emissions is essential. From a long-term perspective, it will allow to guide the recipe formulation of the initial mixture to be composted, with a view to reducing gas emissions during composting. This study gathered literature data targeting sewage sludge composting and performed statistical correlation analyses between cumulative gas emissions and the following parameters: sewage sludge, bulking agent and composted mixture initial physicochemical parameters (pH, dry matter, total carbon, total nitrogen, C/N), the dry mass ratio of sewage sludge to bulking agent and the duration of composting. The average values of cumulative emissions show a large variability: 1.37 ± 2.71 gC.kg initial mix DM−1, 0.13 ± 0.17 gN.kg initial mix DM−1 and 2.23 ± 2.79 gN.kg initial mix DM−1 for CH4, N2O and NH3 emissions respectively. Although the correlation analysis highlighted some significant interesting correlations between initial physicochemical parameters and gas emissions (p.value < 0.05), reliable multiparametric model could not fit the data, meaning that the actual literature data are not sufficient to explain most part of gas emissions. Among the most interesting relationships, the study showed that the dry matter of the composted mixture is negatively correlated to N2O emissions, while the ratio of sewage sludge to bulking agent and the duration of composting are positively correlated to N2O emissions. It was also shown that the pH of the bulking agent is positively correlated to NH3 emissions. Considering the large part of the emission variability that is not explained and the difficulty to link the correlation with their causality, it will be interesting to improve composting gas emissions knowledge in future research by analyzing free air space, bulking agent adsorption capacity and available and biodegradable organic matter. These parameters are of particular interest in solving the main problems associated with sewage sludge composting, namely porosity and nitrogen retention. This study also highlighted the necessity to extend the duration of the composting studies over 40 days in order to measure possible N2O late release and better identify parameters influencing N2O emissions.

Formulation of a Three-Component Essential Oil Mixture from Lavandula dentata, Rosmarinus officinalis, and Myrtus communis for Improved Antioxidant Activity.

The optimization of existing natural antioxidants that are highly effective is crucial for advancements in medicine and the food industry. Due to growing concerns regarding the safety of synthetic antioxidants, researchers are increasingly focusing on natural sources, particularly essential oils (EOs). Combining EOs might enhance antioxidant activity due to increased chemical diversity. This study investigates, for the first time, the antioxidant properties of EOs from Lavandula dentata, Rosmarinus officinalis, and Myrtus communis, both individually and in combination, using the augmented-simplex design methodology. The in vitro evaluation of the antioxidant activity was performed using DPPH and ABTS radical scavenging assays. Chromatography gas-mass spectrometry (CG-MS) revealed that 1,8-cineol (37.27%) and pinocarveol (12.67%) are the primary components of L. dentata; verbenone (16.90%), camphor (15.00%), and camphene (11.03%) are predominant in R. officinalis; while cineol (43.32%) is the main component of M. communis. The EOs showed varying scavenging activities against ABTS and DPPH radicals, with DPPH assay values ranging from 194.10 ± 3.01 to 541.19 ± 3.72 µg/mL and ABTS assay values ranging from 134.07 ± 1.70 to 663.42 ± 2.99 µg/mL. These activities were enhanced when the EOs were combined. The optimal antioxidant blend for DPPHIC50 consisted of 20% L. dentata, 50% R. officinalis, and 30% M. communis. For the highest ABTS radical scavenging activity, the best combination was 18% L. dentata, 43% R. officinalis, and 40% M. communis. These results highlight the potential of EO combinations as new natural formulations for use in cosmeceutical, food, and pharmaceutical sectors.

Sustainable and Scalable Synthesis of Acetal-Containing Polyols as a Platform for Circular Polyurethanes.

Polyurethanes (PUs) are highly versatile polymers widely utilized across industries. However, chemical recycling of PU poses significant challenges due to the harsh conditions required and the formation of complex mixtures of oligomers upon depolymerization. Addressing this inherent lack of recyclability, we developed closed-loop recyclable PU materials by integrating cleavable acetal groups. We present a sustainable and scalable synthesis method for acetal-containing polyols (APs) through aldehyde-diol polycondensation, utilizing reusable heterogeneous catalysts. Three APs with different hydrolytic stabilities depending on the structure of acetal groups were synthesized from formaldehyde, acetaldehyde, and propionaldehyde with 1,6-hexanediol (H16). These APs were employed alongside 4,4'-methylene diisocyanate (MDI) for preparation of PU materials. The resulting PUs exhibited mechanical properties comparable to or surpassing those of conventional PUs, while demonstrating excellent recyclability under acidic conditions. Notably, hydrolysis of PU materials based on acetaldehyde-derived APs yielded remarkable monomer recovery rates, with 89 % for H16 and 84 % for 4,4'-methylenedianiline, a precursor to MDI. Furthermore, we successfully demonstrated closed-loop recycling by synthesizing APs from recovered H16, resulting in PU materials with identical properties to the original PU. This achievement highlights the potential for establishing a closed-loop recycling system for acetal-containing PUs, contributing to the advancement of a sustainable and circular economy.

Effectiveness of Gas Recombination Catalyst Layers in Mitigating H2 Crossover in PEM Water Electrolyzers Operating at High Differential Pressure

Gigawatt-scale deployment of proton exchange membrane water electrolyzers (PEMWE) to produce green hydrogen at $1/kg of H2, the US department of energy’s (DOE) ultimate cost target, requires the use of thinner membranes to reduce ohmic losses at high current densities as well as differential pressure operation to improve the overall system efficiency.1 High differential pressure operation results in significant hydrogen crossover through PEMs leading to safety concerns due to the formation of a flammable gas mixtures at anode (> 4% H2 in O2).2 Therefore, the successful deployment of PEMWEs at scale relies on successful implementation strategies to reduce the hydrogen concentration at anode to enable safe operation at high efficiency. These strategies include incorporating gas recombination catalyst (GRC) in the membrane, PTL or downstream in the anode gas outlet. However, the impact of GRC layers on PEMWE performance and hydrogen crossover rates at high differential pressure is not well understood.In this work, we employ in-operando gas chromatography coupled with thermal conductivity detector along with PEMWEs operating at differential pressures (up to 30 bar) to quantify hydrogen crossover rates through PEM at differential pressure. Using this setup, we evaluate the effectiveness of gas recombination layers incorporated in PEMWE membrane electrode assemblies (MEA) in mitigating the risk of formation of the flammable gas mixture. Further, we will also discuss implications of high differential pressure operation on PEMWE performance, durability, and operational safety.

Phase behaviour and heat capacities of DBN and DBU based protic ionic liquids – Insights into the ionic character and nanostructuration

Herein, we report the thermal behavior and high-precision heat capacity values, at T = 298.15 K, and in the range from 283 to 363 K, for several protic ionic liquids (PILs), derived from the 1:1 liquid mixtures of the organic superbases 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with some carboxylic acids (propionic, butyric, hexanoic and octanoic). Glass transition, Tg, crystallization, Tc, cold-crystallization, Tcc, and melting, Tm, temperatures were determined for the PILs studied, showing marked differences with the base – Tg is lower for all DBN PILs, and no Tm, Tc, and Tcc could be obtained for the DBU PILs. The standard molar heat capacities, Cp,m0, were obtained with an uncertainty of less than ±0.3 % and their dependence on the base and on the acid’s chain length was studied in detail. The Cp,m0 of the DBU PILs were found to be significantly higher than those of the corresponding DBN PILs, which corroborates the greater ionic character of DBU PILs. The heat capacity data suggested the existence of a trend-shift with the chain length of the carboxylic acid. Similar to aprotic ionic liquids, the shift occurs around n = 5 (pentanoic acid) and suggests the existence of some degree of nanostructuration into polar and non-polar domains in PILs with larger acids. Moreover, PILs can display abnormally high excess heat capacities, resulting from the formation of an ionic mixture from neutral species. Analysis of the calculated excess heat capacities indicates that PILs tend to become less ionic as the temperature increases, which goes in accordance with the acid-base equilibrium shift.

Alternating Graft Copolymer Carrying PLA Graft Chains at Every Other Unit: Sequence Impacts on Crystallization Behaviors.

Alternating graft copolymers were precisely synthesized via selective cyclopolymerization of pendant-transformable divinyl monomer (1), post-polymerization modification via aminolysis with alkylamine, and ring-opening polymerization of l-lactide (LLA) from the hydroxy pendant group in alternating sequence. The poly(LLA) (PLLA) graft chain on the alternating copolymer gave a higher crystallization degree on the isothermal treatment than that on the random counterpart likely because of the periodic sequence. The comonomer pendant group from alkylamine in the aminolysis reaction in the alternating sequence affected the crystallization behaviors, and the oligoethylene glycol (OEG) group promoted the crystallization thanks to the larger free volume effect. As for the stereocomplex formation of the racemic mixture of enantiomeric PLLA and poly(d-lactide) (PDLA) chains, the alternating graft copolymer gave a higher degree of stereocomplex crystallization in the mixture with the enantiomer homopolymer than the random analogue.

Effect of intermediate processing treatment on the structure and mechanical properties of Al–4 wt%Cu–3 wt%Mn alloy manufactured by electromagnetic casting followed by high-pressure torsion (HPT)

In this work, a thermally stable model Al–4Cu–3Mn (wt%) alloy has been manufactured by electromagnetic casting (EMC), followed by compression, intermediate heat treatment and high-pressure torsion (HPT). Structural changes of the alloy during subsequent processing stages have been analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the X-ray diffraction (XRD). The results indicate that variations in the intermediate heat treatment temperature of the compressed samples lead to a significant difference in strain hardening and thermal stability after HPT. According to microstructure investigations the hardening of samples processed by HPT resulted from formation of mixture of grains and subgrains with high dislocation density as well as mechanical fragmentation of eutectic Al2Cu particles and precipitation of nanoscale Mn-rich dispersoids which are identified as Al6Mn. The intermediate heat treatment of the EMC rod at 350 ºC for 3 hours and heat treatment of HPT sample at 250 ºC for 5 hours exhibited the best mechanical properties in terms of ultimate tensile strength (UTS), yield strength (YS) and elongation (El), reaching 610 MPa, 560 MPa and 10 % respectively. At the same time intermediate annealing at 450 °C makes the HPT processing ineffective.

Effects of continuous variable valve timing and duration on fuel/air mixture formation

With increasing global regulations on particulate emissions, the particulate matter and number released under cold start and high-load conditions have become crucial. Under such conditions, the particulate emissions from port fuel injection engines can be significant and comparable to those from gasoline direct injection engines. In this case, fuel evaporation and mixture formation contribute to the reduction in particulate emissions. One method to improve these characteristics is to enhance the in-cylinder flow and turbulence kinetic energy. Therefore, in this study, we investigated the effect of in-cylinder flow enhancement on the particulate emissions reduction in port fuel injection engines. Simulations were conducted with various intake valve timings and durations under cold-start conditions. We then performed engine experiments to confirm the reduction in particulate number. The results showed that the relationship between the intake valve open timing and piston speed was crucial. Opening the intake valve to its maximum value slightly after the point of peak piston velocity resulted in a higher flow intensity and turbulence kinetic energy during the compression stroke. In addition, the experimental results indicated that improving the in-cylinder flow using continuous variable valve timing reduced the particulate number by 27.51 %.

Investigating agglomeration behavior of recycled asphalt mixtures in mixing stage using discrete element method

The inclusion of clusters in recycled asphalt pavement (RAP) materials has a substantial negative impact on the mechanical properties, particularly affecting the homogeneity formation in recycled asphalt mixtures. Hence, it is imperative to gain insight into the agglomeration and dispersion of RAP materials during the mixing stage. Due to experimental limitations, this study opted for the discrete element method (DEM) as an alternative approach to simulate the mixing process of hot recycled asphalt mixtures containing RAP clusters. The impact of RAP cluster sizes and aging degree was examined. Parameters for the parallel bond model were determined through static loading and stacking angle tests, while contact bond number and dispersion coefficients were calculated to assess the agglomeration and dispersion behaviors of hot recycled asphalt mixtures. The results indicated that an increase in total bond number and a decrease in RAP-RAP bonds demonstrated the formation of new clusters during the mixing process. A critical cluster size (7.1 mm in this study) was identified, requiring more mixing effort for dispersion. Although following the same principle, the influence of aging degree on RAP materials was found to be significant.

Acoustic frequency-based method for high-speed aircraft combustion analysis and hybrid artificial intelligence diagnostics

In the paper, a method of high-speed continuous combustion monitoring for jet aircrafts, based on acoustic data processing, is proposed. As part of the research, acoustic signals corresponding to the specific phases of the combustible mixture formation and its combustion were separated. They were assigned to the generated process energy value. In the result, parametric functions were obtained in multidimensional spaces of states and processes. Parameters and acoustic characteristics in the amplitude, frequency and JTFA domains constituted information about particular symptoms in the jet engine, thanks to which reference waveforms of signals and forms for specific malfunctions were mapped. The above graphic characteristics have been parameterized to determine their diagnostic reliability factors.The method is verified by empirical signals obtained from turbojet propulsion system in time and power dependent conditions. Appropriate exothermic combustion phases were assigned for the determined acoustic spectra, taking into account the obtained power. Then, representative diagnostic parameters transformed in the process values domain were calculated. Finally, monitoring functions and algorithms of combustion efficiency with determination of malfunctions sources (at dynamic conditions) are proposed.As a result, it is possible to identify first outbreaks of design and process failures during fuel injection and combustion in aircrafts, taking into account artificial intelligence methods. The obtained results indicate it is possible to adapt the acoustic characteristics of the spectra and their discrete representatives, for appropriate states and failures, to detect first dangerous symptoms in the aircraft during flight conditions (supporting OBD with the acoustic adaptive diagnostic procedures).