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Power characteristics are important indicators of fuel cell performance. In the actual operation of fuel cells, changes in operating conditions lead to variations in their power characteristics. Therefore, it is imperative to explore the impact of operating conditions on power characteristics. This paper analyzes the factors influencing fuel cell power and uses sensitivity analysis to investigate how different factors affect fuel cell performance. The operating parameters are optimized using a Bayesian-optimized Gaussian process regression model. The research results indicate that temperature has the greatest impact on fuel cell power, followed by stoichiometry and backpressure. The Bayesian-optimized Gaussian process regression model performs the best, reducing its RSME from 0.1 to 0.0556. Residual analysis and regression characteristic analysis verify the optimized model's improved fitting and regression characteristics. Based on the Bayesian–Gaussian process regression model, the optimized operating parameters are obtained for maximum power: a temperature of 80 °C, stoichiometry of 4, and backpressure of 1.7 bar. This paper provides theoretical support for improving fuel cell performance. [ABSTRACT FROM AUTHOR]

The power battery configuration of an extended-range electric vehicle directly affects the overall performance of the vehicle. Optimization of the output voltage of the power battery can improve the overall power and economy of the vehicle to ensure its safe operation. Factors affecting the output voltage of power batteries under different operating conditions, such as nominal voltage and the number of series and parallel connections of the battery cells, have been studied. This study uses AVL Cruise to establish an overall model of an extended-range electric vehicle to simulate the output voltage characteristics under the different operating conditions of the NEDC (New European Driving Cycle), WLTC (World Light Vehicle Test Cycle) and CLTC (China Light Duty Vehicle Test Cycle). The influence of the output voltage of the power battery under different operating conditions is studied to ensure that the power battery can output energy with high efficiency. The operating conditions have an impact on the output voltage with an idle voltage fluctuation of the operating conditions. The nominal voltage variation and the number of series and parallel connections of the battery cells affect the frequency and time of breakdown. [ABSTRACT FROM AUTHOR]

A computational model was developed to investigate the significance of system design and operating conditions on the rejection of neutral, low‐MW organics by reverse osmosis for potable reuse. The model demonstrated that the decrease in local rejection as net driving pressure decreases is substantially greater for moderately rejected compounds than for highly rejected compounds. At recovery values less than 70%, the local permeate concentration can exceed the pressure vessel feed concentration for moderately rejected compounds. System‐level rejection of moderately rejected compounds is likewise substantially more sensitive to operating conditions than highly rejected compounds. The findings highlight a drawback of relying on rejection results from bench‐scale testing that operates at low recovery, which invariably has higher rejection than full‐scale systems operating at similar pressure. The analysis demonstrates a trade‐off in which the low‐pressure, high‐recovery operation desired for potable reuse systems can be detrimental to the removal of low‐MW neutral organics. The removal of low‐MW neutral organics can be improved if organics rejection is explicitly evaluated during the design process. [ABSTRACT FROM AUTHOR]

A one-dimensional computational model has been developed that can be used to identify operating conditions for the cathode side of a proton exchange membrane fuel cell such that both the inlet and outlet relative humidity is equal to 100%. By balancing the calculated pressure drop along the cathode side flow channel with the change in molar composition, inlet conditions for the cathode side can be identified with the goal of avoiding channel flooding. The channel length, height, width and the land-to-channel width ratio are input parameters for the model so that it might be used to dimension the cathode flow field. The model can be used to calculate the limiting current density, and we are presenting unprecedented high values as a result of the high pressure drop along the flow channels. Such high current densities can ultimately result in a fuel cell power density beyond the typical value of 1.0–2.0 W/cm2 for automotive fuel cells. [ABSTRACT FROM AUTHOR]

The convective hot-air drying technology can cause physicochemical, nutritional, and organoleptic losses in the mango (Mangifera indica). The present Systematic Review was carried out with the objective of comparing mango dehydration technologies to identify the effects on the physicochemical, nutritional, and organoleptic properties of the fruit. Through a review of published scientific and conference papers in the Scopus database, adjusted to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) methodology, a total of 134 documents dated between 2000 and December 6 of 2022 were obtained; 76 of these documents were finally included in the bibliographic and theoretical analysis. Selection parameters emphasizing the relationship between the articles and the research topic, evidenced by including at least one of three dehydration technologies and the fruit of interest with an experimental or theoretical approach to the dehydration subject; review articles and surveys were excluded. Correlation graphs of bibliographic variables were made using the data mining software VantagePoint (version 15.1), which was graphically restructured in Microsoft Excel with the support of statistical analysis. Of the resulting articles, it was found that the countries with authors who participated most in scientific production like India, Brazil, Colombia, the United States, and Thailand, were those related to mango production or importation. Furthermore, the freeze-drying technology allows operating at lower temperatures than convective hot-air drying, contributing to the preservation of ascorbic acid, among other compounds. The refractance window has the shortest operation time to obtain moisture values between 10 and 20%. The dehydrated samples using the refractance window are smooth, homogeneous, non-porous, and comparable to the color obtained with freeze-drying, which is acceptable for industrial applications. [ABSTRACT FROM AUTHOR]

A one-dimensional computational model has been developed that can be used to identify operating conditions for the cathode side of a proton exchange membrane fuel cell such that both the inlet and outlet relative humidity is equal to 100%. By balancing the calculated pressure drop along the cathode side flow channel with the change in molar composition, inlet conditions for the cathode side can be identified with the goal of avoiding channel flooding. The channel length, height, width and the land-to-channel width ratio are input parameters for the model so that it might be used to dimension the cathode flow field. The model can be used to calculate the limiting current density, and we are presenting unprecedented high values as a result of the high pressure drop along the flow channels. Such high current densities can ultimately result in a fuel cell power density beyond the typical value of 1.0–2.0 W/cm2 for automotive fuel cells.

The convective hot-air drying technology can cause physicochemical, nutritional, and organoleptic losses in the mango (Mangifera indica). The present Systematic Review was carried out with the objective of comparing mango dehydration technologies to identify the effects on the physicochemical, nutritional, and organoleptic properties of the fruit. Through a review of published scientific and conference papers in the Scopus database, adjusted to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) methodology, a total of 134 documents dated between 2000 and December 6 of 2022 were obtained; 76 of these documents were finally included in the bibliographic and theoretical analysis. Selection parameters emphasizing the relationship between the articles and the research topic, evidenced by including at least one of three dehydration technologies and the fruit of interest with an experimental or theoretical approach to the dehydration subject; review articles and surveys were excluded. Correlation graphs of bibliographic variables were made using the data mining software VantagePoint (version 15.1), which was graphically restructured in Microsoft Excel with the support of statistical analysis. Of the resulting articles, it was found that the countries with authors who participated most in scientific production like India, Brazil, Colombia, the United States, and Thailand, were those related to mango production or importation. Furthermore, the freeze-drying technology allows operating at lower temperatures than convective hot-air drying, contributing to the preservation of ascorbic acid, among other compounds. The refractance window has the shortest operation time to obtain moisture values between 10 and 20%. The dehydrated samples using the refractance window are smooth, homogeneous, non-porous, and comparable to the color obtained with freeze-drying, which is acceptable for industrial applications.

Chemical recycling of Polyethylene Terephthalate (PET) has gotten great attention today. Aminolysis, one of the chemical recycling methods, is the degradation of polyesters using primary amines that attack its functional group. It is not much explored as a commercial recycling technique among the chemical recycling methods. This review aims to explain the aminolysis method of PET degradation in terms of reaction operating conditions such as PET to solvent ratio, temperature, degradation time, and catalyst dosage. The primary product of aminolysis of PET is also discussed and their most common application in the preparation of secondary products is presented. Thus, PET-derived primary products can be used to synthesize polymers such as polyurethane and develop enhanced products like paints and coatings. Additionally, nonconventional procedures of PET aminolysis techniques: such as microwave radiation, ultrasound, UV radiation, and sunlight were assessed by comparison. [ABSTRACT FROM AUTHOR]

Proton exchange membrane electrolytic cell (PEMEC) is considered a promising way to produce green hydrogen due to its advantages of high current density, rapid start and stop, and high purity of hydrogen production. However, the existing macroscopic modeling of the PEMEC lacks the consideration of MPLs and the comprehensive study of heat and mass transport. In this paper, a one-dimensional two-phase non-isothermal PEMEC model with microporous layers is established, which accounts for a complete description of mass, charge, and heat transport. The polarization curves of numerical simulation are in good agreement with the experimental data. Then, the model is used to parametric analyze the effects of operating conditions and component parameters on heat and mass transfer, voltage loss, and efficiency for the PEMEC. The results show that operating pressure has a significant influence on the electrolytic performance. Voltage loss reduced of 30.75 mV and maximum temperature of 1.74 K occur when operating pressure increases from 1atm to 3atm, respectively. The characteristics of PTL and MPL mainly affect mass transport, and when PTL thickness and MPL thickness reduce by 100 μm and 20 μm respectively, the oxygen molar fraction reduces by 4.96% and 0.94%, respectively. The application of higher porosity, permeability, and thinner PTL with a thinner microporous layer (MPL) can effectually improve the operation efficiency of PEMEC. The model results presented in this study provide a theoretical basis for the optimization and design of the PEMEC. • A 1D two-phase, non-isothermal macroscopic model of a PEMEC with MPLs is presented. • The model is validated against experimental data from literature. • A parametric analysis of operating condition and component parameter are performed. • Operating condition of High voltage, high temperature and high operating pressure are desirable. • Requiring thin PTL with high porosity and low permeability is coated with thin MPL. [ABSTRACT FROM AUTHOR]

The first focus of this study is to investigate the design and behavior of locally built solar dryer during processing henna leaves. This was performed through the determination of the most important parameters that effect drying process. Appropriately, it was found that solar radiation has a direct effect on the collector outlet air temperature and consequently the product moisture content. Accordingly, high radiations lead having high air temperature at the drying chamber and consequently, the moisture content will decrease rapidly. Similarly, lower radiations will still lead to decrease of the moisture content, however, the drying rate will be less important than at high radiations. On the other hand, air velocity has an inverse dissipative effect of the energy and its increase leads to the decrease of the outlet temperature of the solar collector. Indeed, the highest outlet temperature from the solar collector was around 32 °C at an air velocity of 2 m/s. At 5.5 m/s, this temperature dropped to around 27 °C. The second objective of this study is to present the effect of different drying methods (i.e. forced convective solar drying and open sun drying) of Lawsonia inermis on the content of secondary metabolites (phenolic and flavonoid compounds) and compare the results with fresh henna samples. The yield of phenolic compounds was determined, and the dry crude extracts were found to be richer than the fresh sample in all of the drying modes used. The best yields are obtained with convective solar dryer and open sun drying samples (28.6 and 13.93%), respectively. The total phenolic and flavonoid contents of convective solar dryer product were 25 and 10% higher than open sun dried samples. Antioxidant tests (DPPH, ABTS, and ferric reducing power) revealed the scavenging and reducing abilities of the extract dried with the solar dryer. The values of antioxidant capacities measured by the three different methods were all consistent, appropriate, and highly correlative for assessing total antioxidant capacities. The solar dryer allows the preservation or even the increase of the antioxidant activity of the tested extracts. [ABSTRACT FROM AUTHOR]

Metal-polymer composite materials were tested at ambient temperatures of 20 and 60 °C. The most modern composite wear-resistant materials used in mechanisms as sliding bearings were used. The relevance of the tests is determined by the application of worldwide trends to mechanisms without maintenance for the entire life cycle. The influence of temperature on the wear resistance of metal-polymer composite materials that can be used in aviation spherical plane bearings is determined. It was determined that heat generation caused by both the friction process and dynamic load as a result of reverse motion has the greatest influence on the wear intensity. Increasing the test temperature affects polymer composite materials to a greater extent than metal-polymer tape. At this stage, a significant role in wear resistance is played with the ability of the material to dissipate heat, which occurs in the contact zone from reversible sliding. It has also been established that the carbon fabric of the Fluroglide material can withstand higher temperatures than the babbitt of the metal-polymer tape. A key role in the durability of spherical plane bearings that work in non-standard temperatures will be played by the composite materials design selection and the polymer materials themselves for specific operating conditions [ABSTRACT FROM AUTHOR]

Operation at high current density of polymer electrolyte membrane electrolysis cell (PEMEC) can reduce its electrode area and capital expense. The high current density operation is limited by the limiting current density (LCD), where electrolysis voltage abruptly increases. Effects of operating temperature and pressure on the LCD were evaluated in a lab-scale PEMEC within a range from 70 to 90 °C and from 0.1 to 0.3 MPa. Also, a theoretical model was developed to predict the LCD, and to clarify what determines LCD and how the operating conditions influence the LCD. The theoretical analysis suggests that when current density is close to the LCD, water mass transport at anode reaches a limitation, which indicates that water saturation reaches almost zero at anodic catalyst layer. The analysis also finds that lower operating temperature and higher operating pressure can reduce oxygen gas saturation and raise the water saturation in porous transport layer at anode, and finally enlarge the LCD. • Limiting current density (LCD) is decided by mass transport limitation. • Oxygen gas saturation near catalyst layer is close to 1 at LCD. • Bubble overvoltage abruptly rises at LCD. • Lower temperature and higher pressure enlarge LCD. [ABSTRACT FROM AUTHOR]

Due to high greenhouse gas emissions, countries worldwide are stepping up their emission reduction efforts, and the global demand for new, carbon-free fuels is growing. Ammonia (NH3) fuels are popular due to their high production volume, high energy efficiency, ease of storage and transportation, and increased application in power equipment. However, their physical characteristics (e.g., unstable combustion, slow flame speed, and difficult ignition) limit their use in power equipment. Based on the structural properties of the power equipment, NH3 fuel application and emissions characteristics were analyzed in detail. Combustion of NH3 fuels and reduction measures for NOx emissions (spark plug ignition, compression ignition, and gas turbines) were analyzed from various aspects of operating conditions (e.g., mixed fuel, fuel-to-exhaust ratio, and equivalence ratio), structure and strategy (e.g., number of spark plugs, compression ratio (CR), fuel injection, and ignition mode), and auxiliary combustion techniques (e.g., preheating, humidification, exhaust gas recirculation, and secondary air supply). The performance of various NH3 fuel cell (FC) types was analyzed, with a focus on the maximum power achievable for different electrolyte systems. Additionally, the application and NOx emissions of indirect NH3 FCs were evaluated under flame and catalytic combustion conditions. The system efficiency of providing heat sources by burning pure NH3, anode tail gas, and NH3 decomposition gas was also compared. Based on a comprehensive literature review, the key factors influencing the performance and emissions of NH3-powered equipment were identified. The challenges and limitations of NH3-powered equipment were summarized, and potential strategies for improving efficiency and reducing emissions were proposed. These findings provide valuable insights for the future development and application of NH3 FCs. [ABSTRACT FROM AUTHOR]

High-voltage heat release from batteries can cause safety issues for electric vehicles. Relevant scientific research work is carried out in the laboratory. The battery safety of laboratory experiments should not be underestimated. In order to evaluate the safety performance of batteries in the laboratory testing of driving conditions of electric vehicles, this paper simulated and compared the discharge characteristics of two common batteries (lithium iron phosphate (LFP) battery and nickel–cobalt–manganese (NCM) ternary lithium battery) in three different operating conditions. The operating conditions are the NEDC (New European Driving Cycle), WLTP (World Light Vehicle Test Procedure) and CLTC-P (China light vehicle test cycle) for normal driving of electric vehicles. LFP batteries have a higher maximum voltage and lower minimum voltage under the same initial voltage conditions, with a maximum voltage difference variation of 11 V. The maximum current of WLTP is significantly higher than NEDC and CLTC-P operating conditions (>20 A). Low current discharge conditions should be emulated in teaching simulation and experiments for safety reasons. The simulation data showed that the LFP battery had good performance in maintaining the voltage plateau and discharge voltage stability, while the NCM battery had excellent energy density and long-term endurance. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) is an energy-efficient technology for wastewater nitrogen removal. However, the byproduct nitrate has hindered development and application of anammox process. Meanwhile, the knowledge of nitrate formation during anammox process is insufficient, which prohibits high nitrogen removal. This review firstly summaries and discusses valuable findings on nitrate formation, including molecular mechanism of nitrate production, microbial pathway of nitrate reduction and its net formation. Specially, influences of operating conditions on mechanisms and patterns of nitrate formation are analyzed. Then, based on nitrate formation mechanism, current strategies of nitrate removal from anammox process are reevaluated. Finally, the key knowledge gaps and further process development are presented. Overall, this review sheds light on the understanding of nitrate formation of anammox process, which would further facilitate and optimize the process design and operation for high performance nitrogen removal.

The article deals with the issues of the scope and sequence of fire-technical equipment tests. There is shown the difference in tests within product commissioning and during tests confirming the daily performance of products. There is considered the question about the need to develop GOST-type standards on the topic of product testing in conditions close to real operation.

Transient vehicle dynamics are deeply affected by the spatial distribution of tire temperature, heat generation, and heat dissipation capacity. However, the tire testing process involves numerous parameters, adding the complexity to monitoring the tire's thermal properties variation. To address this issue, this paper proposes a data-driven framework that combines the well-known Magic Formula with scaling factors and a long- and short-term memory (LSTM) neural network. The framework forecasts tire thermal properties and functionality under given conditions by learning from time-series data on tire operating conditions and mechanical characteristics. It predicts future spatially varying thermal properties of the tire, including temperatures, heat generation, and heat dissipation. This is achieved with a high degree of forecasting ability quantified by train size/test size ratios equaling 22 and 38% with an impressive Relative Root Mean Square Error (RRMSE) around 1−2%. Here, this framework is applied to quantify the impacts of various operating conditions, including vertical load, slip angle, and vehicle speed, on heat transfer for three crucial radial positions on the tire. Our results show that the vertical load is the primary influencing parameter among all operating conditions. The knowledge about transient tire dynamics will be advantageous to their performance optimization. [ABSTRACT FROM AUTHOR]

The operating conditions of the production process significantly influence the resulting dimensional and form accuracy of the workpiece. The operating conditions include the position of the workpiece location, with internal and external heat sources influenced not only by the machine location but also by its operation. In addition, there are the cutting conditions and the feed rate requirements of CNC machine tools. These changes, such as workpiece position, feed rates, and machine heat load, are further reflected in the ability of the machine to run at the position required and interpolate within the given tolerances of circularity. For the accuracy and repeatability of positioning, the machine was set up according to ISO 230-2 and for the circular interpolation tests according to ISO 230-4. The obtained results show the importance of attention to the appropriate setting of the operating conditions of the production process, where the knowledge of the geometric accuracy of the CNC machine tool in its working space can systematically increase the manufacturing accuracy itself or be another tool suitable for predicting the dimensional and form accuracy of workpieces. [ABSTRACT FROM AUTHOR]

The reliability of a car engine is ensured by the combination of oil properties that are laid in the oil production process. The properties of engine oil change with the mileage of the car compared to the initial state. When the rejection parameters of the oil reach the limit level, then it is necessary to replace the old oil with a new one. The rate of change intensity in the properties of particular oil depends on both the make of the vehicle and the operating its conditions. In difficult conditions of operation of the car, it is necessary to reduce the run period of between oil changes. But if the car is operated in light or gentle conditions, then the normative oil change may not realize its full potential. In this case, extending the oil change intervals beyond the norm leads to an increase in the efficiency of its use, which reduces the overall operating costs. It will be optimal when the service life of the oil will be determined by the actual state of the basic properties. The paper presents the results of experimental studies on changes in the concentration and rate of iron entry into motor oil. In addition, other indicators of oil in samples were determined: the viscosity, the flash point in an open crucible, the dielectric constant, the acidity and alkali numbers. The study involved motor oils of the same group, but from different manufacturers, for various brands of trucks and cars at different stages of the life cycle. The energy loading on the engine can be estimated by fuel consumption, which depends on the operating speed or operating conditions of the vehicle. An analysis of the results experiment was carried out, which established a relationship between the concentration of iron in oil and fuel consumption or car mileage. In conclusion, recommendations are given on the values of indicators at which further operation of oils is not recommended. [ABSTRACT FROM AUTHOR]

In order to solve the safe construction and high-quality performance of super-large caisson in long-period wave areas on the west coast of Africa, the wave monitoring data for 30 years in the construction area and the construction difficulties of the supporting project were investigated and analyzed. Based on the measured data of long-period waves in the sea area, the joint distribution and probability statistics of significant wave height and spectral peak period, as well as the conditions of continuous construction operation, were analyzed. The probability distribution law of significant wave height and spectral peak period and the most favorable working time of different projects were obtained, and the guiding opinions for construction operations in the sea area were given, which provides a basis for the research on the construction deployment of super large caisson in long-period wave areas. [ABSTRACT FROM AUTHOR]

Copyright of German International Journal of Modern Science / Deutsche Internationale Zeitschrift für Zeitgenössische Wissenschaft is the property of Artmedia24 and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current study is basically focused on investigating the possible ways to enhance the lubricating oil film performance and hence ship energy efficiency of marine journal bearings in general terms. For the intended purpose, a novel numerical Circumferential Grooved Bearing (CGB) model was developed to assess journal bearing operating conditions based on versatile simulation analyses. Prior to all conducted test trials, the model validation has been confirmed based on the conformity between numerical outcomes and those derived from experimental procedures depending on Universal Journal Bearing Test Rig. CGB performance was evaluated at slow speed variations from 25 rpm up to 125 rpm and different applied loads utilizing the two lubricant oil grades of 5W40 and 0W30. Reducing shaft rotational speed by 80% was found to incur a reduction in the maximum oil film pressure value by 1.17 bar and 0.97 bar for the two aforementioned lubricants respectively. Further, the increase of applied loads from 1079 N up to 1471 N at a constant speed of 75 rpm reduces the maximum oil film pressure ratio by 0.14 and 0.18 for the two oil grades subsequently.

Heat exchanger optimization is a very efficient thermal design inquiry. The goal of the research is to determine an optimal channel flow velocity as well as an optimal total plate number based on overall information on the effectiveness of employing chilled water to cool soybean milk. Heat transfer coefficient, Prandtl number, Reynolds number and pressure drop measurements were applied for milk and water. The rheological properties of soybean milk have been investigated at various temperatures (5, 10, 30, 50, 70 and 90 °C). The operational circumstances of PHE in soybean procedures were investigated at different numbers of plates, flow rates and flow velocities. Based on the present study, total substances showed non-Newtonian pseudoplastic conduct in any respect at any temperature and the power law model has a decent correlation. The cost estimation of the plate heat exchanger was observed at the lowest flow velocity of (2.25) m/s and number of plates is 17.

Increasing the net power density of proton exchange membrane fuel cell without extra cost is beneficial to its commercialization. To this end, a one-dimensional, two-phase, non-isothermal model was developed in this work. The influences of cathode catalyst layer compositions including the mass ratio of ionomer to carbon (Ri/c) and mass ratio of platinum to carbon (Rpt/c) and operating conditions including temperature, cathode relative humidity (RHc), anode relative humidity (RHa), and operating voltage (V) on the cost and performance of fuel cell were quantitatively investigated by range and variance analyses based on an orthogonal test. The results indicate that Ri/c is the most significant factor affecting net power and unit power price. In addition, the RHc and V are also sensitive parameters to the net power, while Rpt/c affects the unit power price. Finally, with the consideration of the interaction between the operating conditions and the cathode catalyst layer compositions, a multi-objective optimization was conducted to improve the aforementioned two indicators. Compared to the base case, the optimized fuel cell achieves a net power increase of 50.8% and a 24.7% reduction in unit power price, which allows the realization of a high-performance, low-cost fuel cell. [ABSTRACT FROM AUTHOR]

The current study is basically focused on investigating the possible ways to enhance the lubricating oil film performance and hence ship energy efficiency of marine journal bearings in general terms. For the intended purpose, a novel numerical Circumferential Grooved Bearing (CGB) model was developed to assess journal bearing operating conditions based on versatile simulation analyses. Prior to all conducted test trials, the model validation has been confirmed based on the conformity between numerical outcomes and those derived from experimental procedures depending on Universal Journal Bearing Test Rig. CGB performance was evaluated at slow speed variations from 25 rpm up to 125 rpm and different applied loads utilizing the two lubricant oil grades of 5W40 and 0W30. Reducing shaft rotational speed by 80% was found to incur a reduction in the maximum oil film pressure value by 1.17 bar and 0.97 bar for the two aforementioned lubricants respectively. Further, the increase of applied loads from 1079 N up to 1471 N at a constant speed of 75 rpm reduces the maximum oil film pressure ratio by 0.14 and 0.18 for the two oil grades subsequently. [ABSTRACT FROM AUTHOR]

A monopile is the most popular foundation type for wind turbines. However, the dynamic performance of monopile-supported wind turbines under different operating and ground conditions is not fully understood. In this study, an integrated monopile-supported wind turbine model in a wind tunnel was employed to jointly simulate the operating and ground conditions. A series of wind tunnel tests were designed and performed to investigate the dynamic performance of monopile-supported wind turbines. These tests included seven operating conditions (seven wind speeds and corresponding rotor speeds) and four ground conditions (one fixed ground condition and three deformable ground conditions with different soil relative densities). According to the test results, the structural responses and dynamic characteristics were analyzed and discussed. This shows that the assumption of fixed-base support significantly overestimates the natural frequency but underestimates the global damping ratio. With the increase in soil relative density, the natural frequency slightly increases, while the damping ratio decreases more significantly. With the increase in the wind speed and rotor speed, the increase in global damping is larger on softer ground. A regression analysis was performed to estimate the global damping ratio under different operating and ground conditions. [ABSTRACT FROM AUTHOR]

The fretting corrosion machine has been modernized for testing spherical bearings under vibration conditions. The method of research of anti-friction composite materials and coatings for low-frequency reversible movements has been developed. A method for laboratory resource tests of aviation spherical sliding bearings with metal-polymer composite materials in conditions close to real has been developed. [ABSTRACT FROM AUTHOR]

The amount of substation accident oil pool wastewater (SAOPW) generated has been increasing due to the successive addition and renovation of substations, and the discharge of untreated or incomplete treatment outside the station will cause serious environmental pollution problems. In this study, a polyethersulfone (PES) composite ultrafiltration membranes were fabricated using phase inversion method and evaluated them for oil removal from SAOPW. The morphology and functional groups of PES composite membranes before and after filtration were characterized and compared through scanning electron microscopy and Fourier-transform infrared spectroscopy. The effects of operating pressure, feed temperature, initial oil concentration and operating time were systematically investigated using flux recovery and oil removal rate as the indexes of investigation, and the process economy was studied and evaluated. The results showed that the PES composite membrane had a relatively high-water flux of 260.2 (L·m-2·h-1) and a high oil removal rate (≥90%), which could effectively remove oil from water. Besides, its high flux recovery ratio (≥90%) after four filtration and cleaning cycles indicated the excellent performance of this PES composite membrane in the separation of oil--water emulsions. This study confirms the applicability of PES composite membrane for oil removal from SAOPW, providing a promising treatment method for the SAOPW treatment. [ABSTRACT FROM AUTHOR]

In this paper, a tribo‐dynamic model of a helical gear is established. For the lubrication sub‐model, a finite line thermal elastohydrodynamic lubrication model of helical gear is adopted. The lateral vibration, axial vibration of gear and torsional vibration of the gear shaft are considered in the dynamic sub‐model. Results show that the tribological parameters of helical gear under the tribo‐dynamic model deviate significantly from that of the quasi‐static model, especially in the engaging‐in region of tooth pair. The friction excitation mainly affects the vibration along the off‐line‐of‐action direction of the gears. The influence of operating conditions on the tribological and dynamic properties of a helical gear pair is significant, especially in the case related to the characteristic frequency of gears. [ABSTRACT FROM AUTHOR]

Heat exchanger optimization is a very efficient thermal design inquiry. The goal of the research is to determine an optimal channel flow velocity as well as an optimal total plate number based on overall information on the effectiveness of employing chilled water to cool soybean milk. Heat transfer coefficient, Prandtl number, Reynolds number and pressure drop measurements were applied for milk and water. The rheological properties of soybean milk have been investigated at various temperatures (5, 10, 30, 50, 70 and 90 °C). The operational circumstances of PHE in soybean procedures were investigated at different numbers of plates, flow rates and flow velocities. Based on the present study, total substances showed non-Newtonian pseudoplastic conduct in any respect at any temperature and the power law model has a decent correlation. The cost estimation of the plate heat exchanger was observed at the lowest flow velocity of (2.25) m/s and number of plates is 17. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Studying the operating conditions and transportation organization plans of high-speed railway freight express stations has important practical significance for deepening the reform of railway freight and enhancing the market competitiveness of railway express. According to the characteristics of the existing high-speed railway freight express operation mode, this paper analyzes the facilities, equipment and operating conditions of the freight organization operation site. On this basis, six high-speed railway freight express transportation organization schemes are proposed, and the advantages and disadvantages of each organization scheme are compared. It is suggested that in the early stage of the development of high-speed railway express, the piggyback transportation mode should be adopted, using passenger trains or high-speed railway confirmation vehicles. The high-speed railway stations as the origin, destination, and loading and unloading operation sites. In the mid-to-long term, the passenger-freight linking mode can be adopted, using the variable formation train. The high-speed railway station as the loading and unloading operation site, and the train depot as the reorganization operation site of the variable formation train. Or use the passenger and freight collinear mode, running special freight trains at night, going online during the non-skylight period and going off line during the skylight period. The logistics base as the origin, destination, and loading and unloading operation sites. For lines with obvious flat peaks and peak hours, it may also be considered to adopt the driving mode of running on-line during off-peak hours and off-line during peak hours. In the long-term stage, the passenger and freight line mode can be adopted, and a full-day special train for freight trains can be operated. The high-speed railway freight station can be used as the starting point, the final destination, and the loading and unloading operation site. [ABSTRACT FROM AUTHOR]

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The article is devoted to the assessment of vapor permeability of composite membrane textile materials, which are widely used in the production of waterproof light industry products. These are clothes and shoes for active leisure and tourism, special clothes and shoes for workers, firefighters, medical workers, uniform for military personnel and many other products. The range of composite textile materials opens new possibilities for manufacturers of garments to provide protection from adverse weather conditions, improvement of microclimate in underwear space with significant weight reduction of package of materials. Vapor permeability index of composite membrane textile materials is the basic one for determining the level of their comfort. The indicator of water resistance is considered decisive in assessing their quality, since the purpose of composite membrane textile materials is to be waterproof. The authors propose a methodology for determining the vapor permeability of waterproof materials, allowing to simulate various operating conditions, and a device for its implementation. In contrast to the existing means of vapor permeability studies, the device used in the described method allows to create different air flow rate over the samples and to conduct tests at different water temperatures to simulate human sweating. With its help, it is possible to determine the vapor permeability of composite membrane textile materials under conditions close to operating ones and compare these materials with each other. With the help of the developed method and device, eight articles of composite membrane textile materials with different polymer layer structures were tested. According to the results of the study, it was found that the samples of materials with a hydrophilic membrane have the best ability to remove evaporation. Объектом исследования являются композиционные мембранные текстильные материалы, применяемые для изготовления водозащитной верхней одежды. Предметом исследования является уровень паропроницаемости композиционных мембранных текстильных материалов. Цель работы – определение уровня паропроницаемости композиционных мембранных тек- стильных материалов различной структуры. В процессе работы проанализированы условия эксплуатации водозащитной демисезонной одежды для моделирования их в процессе испытаний. Предложена новая методика определения паропроницаемости материалов легкой промышленности, позволяющая моделировать различные условия эксплуатации, и устройство для ее реализации. Проведена оценка водонепроницаемости и паропроницаемости композиционных мембранных текстильных материалов. В ходе исследования паропроницаемости при температуре наружного воздуха +10 °С, скорости обдува – 3 м/с и относительной влажности воздуха 89 % восьми артикулов композиционных мембранных текстильных материалов, различных по структуре и толщине полимерного слоя выявлено, что наилучшей способностью выводить испарения обладают образцы материалов с гидрофильной мембраной. Уровень паропроницаемости исследуемых образцов данной группы варьировался от 4609 г/(м2·24ч) до 6521 г/(м2·24ч). Микроклимат в пододёжном пространстве при эксплуатации водозащитной одежды из таких материалов будет более комфортным для носчика. Предложенный подход к оценке паропроницаемости композиционных мембранных текстильных материалов позволяет обеспечить рациональный подбор материалов в пакет изделий легкой промышленности в соответствии с заданными требованиями. Область применения результатов – текстильная и швейная промышленность.

High-voltage heat release from batteries can cause safety issues for electric vehicles. Relevant scientific research work is carried out in the laboratory. The battery safety of laboratory experiments should not be underestimated. In order to evaluate the safety performance of batteries in the laboratory testing of driving conditions of electric vehicles, this paper simulated and compared the discharge characteristics of two common batteries (lithium iron phosphate (LFP) battery and nickel–cobalt–manganese (NCM) ternary lithium battery) in three different operating conditions. The operating conditions are the NEDC (New European Driving Cycle), WLTP (World Light Vehicle Test Procedure) and CLTC-P (China light vehicle test cycle) for normal driving of electric vehicles. LFP batteries have a higher maximum voltage and lower minimum voltage under the same initial voltage conditions, with a maximum voltage difference variation of 11 V. The maximum current of WLTP is significantly higher than NEDC and CLTC-P operating conditions (>20 A). Low current discharge conditions should be emulated in teaching simulation and experiments for safety reasons. The simulation data showed that the LFP battery had good performance in maintaining the voltage plateau and discharge voltage stability, while the NCM battery had excellent energy density and long-term endurance.

Due to high greenhouse gas emissions, countries worldwide are stepping up their emission reduction efforts, and the global demand for new, carbon-free fuels is growing. Ammonia (NH3) fuels are popular due to their high production volume, high energy efficiency, ease of storage and transportation, and increased application in power equipment. However, their physical characteristics (e.g., unstable combustion, slow flame speed, and difficult ignition) limit their use in power equipment. Based on the structural properties of the power equipment, NH3 fuel application and emissions characteristics were analyzed in detail. Combustion of NH3 fuels and reduction measures for NOx emissions (spark plug ignition, compression ignition, and gas turbines) were analyzed from various aspects of operating conditions (e.g., mixed fuel, fuel-to-exhaust ratio, and equivalence ratio), structure and strategy (e.g., number of spark plugs, compression ratio (CR), fuel injection, and ignition mode), and auxiliary combustion techniques (e.g., preheating, humidification, exhaust gas recirculation, and secondary air supply). The performance of various NH3 fuel cell (FC) types was analyzed, with a focus on the maximum power achievable for different electrolyte systems. Additionally, the application and NOx emissions of indirect NH3 FCs were evaluated under flame and catalytic combustion conditions. The system efficiency of providing heat sources by burning pure NH3, anode tail gas, and NH3 decomposition gas was also compared. Based on a comprehensive literature review, the key factors influencing the performance and emissions of NH3-powered equipment were identified. The challenges and limitations of NH3-powered equipment were summarized, and potential strategies for improving efficiency and reducing emissions were proposed. These findings provide valuable insights for the future development and application of NH3 FCs.

An ammonia converter is a catalyzed reactor that facilitates the synthesis of NH3 (ammonia) from hydrogen (H2) and nitrogen (N2). Several studies have shown that the performance of this reactor significantly influences the operational efficiency and productivity of ammonia plants. Therefore, this study aims to evaluate the performance of an ammonia converter by assessing the effect of operating conditions on the reactant conversion and reaction products using design and actual data. The operating conditions examined included temperature, pressure, ratio of reactants, and inert mole utilized during the NH3 synthesis process. The results showed that the highest NH3 yield of 20.28% was achieved in actual data with 351.5oC temperature, 154.32 kg/cm2 pressure, 3.58 raw material ratio, and 3.57% inert mole (sixth dataset). The performance efficiency of an ammonia converter can be assessed using temperature, reactant ratio, and inert moles, while the pressure factor was insignificant due to dataset fluctuations. Based on the evaluation results, the converter experienced a decrease in performance due to a discrepancy in the existing operating conditions between the design and actual data.

Existing methods and equipment for determining the dynamic characteristics of devices and systems are considered. A new method for estimating the dynamic error of navigation devices is proposed. It makes it possible to simplify the experimental assessment of the dynamic error of serial products as well as to evaluate its value under conditions of real disturbing influences corresponding to operating conditions using test equipment. The method is based on the measurement by the device of pseudo-random test effects reproduced by the stand in a given frequency spectrum corresponding to the operating conditions of the instrument. In this case, the variance of the dynamic error of the device under study is determined as the area under the graph of its power spectral density. To implement the method, it is proposed to use a specialized stand that allows to reproduce oscillations in a given frequency spectrum. The results of the application of the developed method in solving the problems of estimating the dynamic errors of the electronic inclinometer are presented. The results of experimental studies are consistent with the results of field tests obtained earlier. The developed method makes it possible to reduce the time for estimating the dynamic error of sensors and devices to 15–20 minutes because it does not require measurements at each frequency separately, and also allows to evaluate the error of devices in real modes of its operation.

The polymer electrolyte membrane water electrolysis (PEMWE) performance is closely related to the Nafion® ionomer content in catalyst layers (CLs). This study experimentally investigates the impact of anode and cathode Nafion® ionomer contents on the PEMWE performance at high temperatures. The Nafion® ionomer content is 5–30 wt% on both anode and cathode sides, while the temperature and operating pressure change from 80°C to 120°C and 0.1 MPa to 0.3 MPa, respectively. Experimental results reveal that elevated temperature and operating pressure can remarkably promote the performance of PEMWE with a reasonable Nafion® ionomer content and without dehydrating the membrane at 120°C and 0.3 MPa. However, the PEMWE performance deteriorates as the Nafion® ionomer content is too low. The anode Nafion® ionomer content has a relatively great impact on ohmic resistance, concentration, and activation overpotential, especially the concentration overpotential. Nevertheless, the cathode Nafion® ionomer content only affects the ohmic resistance. Finally, under the operating conditions of 120°C and 0.3 MPa, employing a Nafion ionomer content of 10 wt% in the anode–cathode sides minimizes the electrolysis voltage to 2.18 V at 18 A/cm2.

Chlorphenamine (CPA) adsorption onto three activated carbons (ACs), namely, Megapol M (MM), Micro 10 (M10), and GAMA B (GB), was studied in this work. The textural properties, concentrations of active sites, surface charge and point of zero charge of the ACs were assessed. The surface areas (SBET) of MM, GB and M10 were 1107, 812 and 766 m2/g, respectively. The MM surface had an acidic character, while the surfaces of M10 and GB were basic. The adsorption capacity of MM, M10, and GB towards CPA was studied at pH 7 and 11, and the adsorption capacity decreased in the order MM > M10 ≈ GB, which was ascribed to the magnitude of SBET and the concentration of acidic sites. The solution pH significantly increased the adsorption capacity of MM towards CPA by raising the solution pH from 5 to 9, and this behavior was attributed to the electrostatic attraction between the negatively charged surface of MM and the cationic species of CPA. The maximum uptake of CPA adsorbed on MM was 574.6 mg/g at pH = 11 and T = 25 °C. The adsorption capacity of MM was slightly raised by incrementing the temperature. Lastly, the zeta potential measurements of pristine MM and MM saturated with CPA confirmed that the electrostatic attraction predominated in the pH range of 5–9, and the π-π stacking interactions were the principal mechanism of CPA adsorption on MM at pH 11. [ABSTRACT FROM AUTHOR]