Equivalence Ratio Research Articles

Combining solar panels with plants for sustainable energy and food production: state of the art

The need for alternative energy sources becomes extensive because of the escalating cost of fossil fuels. The goal of this paper is to examine the effectiveness of combining photovoltaics and agriculture for better yield. Photovoltaic (PV) solar plants will compete with farms for available land. In this study, the methodologies are discussed how it is possible to maximize land utilization by placing solar arrays and food crops on the same plot of land. The term is proposed "agrivoltaic system" to describe this setup. Conventional solutions (discrimination of agricultural and energy extracting) were compared to two agrivoltaic schemes with varying density of PV arrays using land equivalent ratios. We utilized a crop model to simulate the amount of sunlight reaching the crop from an array of solar panels and to speculate on the yield reduction that would result from the partial shading. These early findings suggest that agrivoltaic systems may be highly effective; the two densities of PV panels were anticipated to boost worldwide land production by 73%. One possible explanation for the success of these hybrid systems is the presence of facilitation mechanisms analogous to those seen in agroforestry. At the end it is suggested that in places where arable land is rare, new solar plants may find it beneficial to produce both power and food.

Control of sulfur number in sulfur-containing compounds: The effect of base type, equivalent of the base, and reaction solvent in synthesizing linear sulfur

Abstract Since the properties of sulfur-containing compounds depend on the sulfur number contained in the compound, it is desirable to develop a method to control the sulfur number. A common method for synthesizing sulfur-containing compounds is to mix sulfur with a base to form linear sulfur, which is then reacted with an organic compound to obtain a sulfur-containing compound. In this study, we systematically investigated the relationship between the type of base, equivalent amount of the base, and the reaction solvent and the sulfur number in the resulting sulfur-containing compound. The sulfur number of sulfur-containing compounds prepared in water was controlled by the equivalent ratio of elemental sulfur (S8) and base. Sulfur-containing compound with high sulfur values was obtained using solvents with low dielectric constants and with lower base equivalents compared to S8.

Robust damping improvement against the vortex-induced vibration in flexible bridges using multiple tuned mass damper inerters

The tuned mass damper inerter (TMDI) is considered as one of countermeasures to mitigate the very-low-frequency vertical bending vortex-induced vibration (VIV) in flexible bridges. However, the control robustness of the TMDI against the system uncertainty is a serious concern due to the limited inerter span capacity. In this paper, the multiple tuned mass damper inerter (MTMDI) is used instead of identical TMDIs to provide a robust equivalent damping ratio against the uncertain VIV within the entire lock-in wind speed range. A design framework of the MTMDI considering the inerter span length is proposed based on a universal VIV model suitable for the fully closed, centrally slotted, and semi-closed box decks. In the framework, the fluctuation of VIV characteristics with the wind speed, the probability of occurrence of the VIV, and the uncertainties in VIV characteristics and deck dynamics are considered, simultaneously. Two objection functions are defined to focus on the maximizing the equivalent damper ratio and reducing the VIV mitigation failure, respectively. Finally, numerical analysis of a flexible bridge-MTMDI system subjected to the VIV is performed. The results show that the wind speed probability distribution plays a role of weighting coefficient in the MTMDI optimization. The choice of the objective function depends on the mass ratio of the MTMDI and the level of the system uncertainty. The well-optimized MTMDI achieved a more robust control result than the TMDI within the entire lock-in wind speed range.

An Experimental Study on Premixed Methane-Air Flame Propagation with Intrinsic Instabilities in a Hele-Shaw Chamber at Various Inclined Angles

ABSTRACT Flame propagation in narrow gaps can manifest intrinsic instabilities with appearance of wrinkles/cells on the reaction front, which is attributed to various physical mechanisms. For instance, the buoyancy effect is believed to be able to either stabilize or destabilize the reaction front depending on the flame propagation direction. In this paper, an experimental study of propagation of premixed methane-air flames at a variety of mixture equivalence ratios (from fuel-lean to fuel-rich) in a narrow gap (12 mm) formed by two parallel plates (termed Hele-Shaw chamber) is conducted. The magnitude of the gravitational component along the direction of flame propagation is manipulated via altering the inclined angle of the rotatable combustion chamber. Evolution features of flame-surface shapes during the propagation process under various conditions are recorded using high-speed imaging. Results show that generations of the flame wrinkles/cells are mainly driven by the Darrieus-Landau (DL) and Rayleigh-Taylor (RT) instability. For slowly propagating flames at an extremely fuel-lean condition, the RT is a pronounced mechanism, showing a stabilizing effect for downward propagating flames and a destabilizing effect for upward propagating ones. For the fast burning system at higher equivalence ratios, the DL plays a predominant role in generating instabilities among all the chamber inclined angles while the RT’s effect is noticeably weakened.

Vigna mungo (L.) Hepper as Heterogeneous Catalyst for Generation of Biodiesel from a Mixture of Multiple Oil Feedstocks

A cost-effective catalyst is essential to reduce the expenses of producing biodiesel. This study is aimed at utilizing the waste of the black gram (Vigna mungo (L.) Hepper) plant as an efficient catalyst for producing biodiesel from a blend of different edible and inedible oils. The catalyst was developed by igniting the dried material and then subjecting it to calcination at 550°C for 2 h. The feedstock was prepared by mixing the oils in an equivalent ratio for the reaction. Various sophisticated techniques such as XRD, FT-IR, XPS, BET, FESEM-EDX, HRTEM, and SAED were employed to characterize the prepared catalyst. The catalyst’s catalytic activity was assessed by transesterification of the oil mixture. The optimized transesterification conditions were 10 wt% of catalyst loading, 9 : 1 of MTOR, 65°C of reaction temperature, and 1.6±0.14 h of reaction time producing 94.79±0.27% of biodiesel yield and 96.86% oil conversion. The calcined catalyst’s alkaline solubility was found to be 2.77 mmol/g, basicity as 0.13 mmol/g, and 14.57 per hour as the turnover frequency (TOF). Catalyst reusability was conducted and found that the catalyst could be reprocessed up to three successive cycles. The synthesized biodiesel’s physicochemical characteristics were assessed and found to conform to ASTM D6751 and EN 14214 requirements.

Performance analysis of pulse detonation ramjet

Abstract A Pulse Detonation Ramjet (PDR) performance evaluation model is established based on the component-based method. The influence law of working parameters of pulse detonation combustor (PDC), PDR geometry parameters, flight speed and altitude on the performance is analyzed. Results are as follows. (1) With the increase of the equivalent ratio, the PDR specific thrust first increases and then decreases, reaching a maximum value around 1.2, but the fuel specific impulse always decreases; (2) The change of inlet throat cross-sectional area has little effect on specific thrust and fuel specific impulse, but the increase of nozzle throat cross-sectional area will have a negative effect; (3) PDR specific thrust and fuel specific impulse increase first and then decrease with the increase of flight Mach number and altitude; (4) Compared with a ramjet engine, the advantage range of PDR can reach 18.04 %, but gradually decreases with the increase of Mach number.

Effect of Flowering Strips in Associated Broccoli and Lettuce Crops on Increasing Land Use Efficiency

Diversifying agroecosystems enhance the sustainability of agricultural production and reduce input dependency during agroecological transitions. To achieve this objective, a study was conducted to assess the impact of intercropping and the introduction of flowering plant strips on land use efficiency and crop damage in a lettuce and broccoli association. The results indicated that the introduction of flowering plant strips alone led to a significant increase in land use efficiency, while intercropping alone did not have any such effect. The efficiency was measured using the land use equivalent ratio (LER), which consistently showed values greater than 1, suggesting a significant increase in efficiency. It should be noted that the presence of flower strips in the crop fields were found to increase the incidence of molluscs and Plutella xyllostella. Additionally, the competitive ratio analysis revealed that broccoli was more competitive than lettuce in the intercropping system. Therefore, farmers can increase the efficiency of land use and profitability by incorporating flower strips in the intercropping systems of broccoli and lettuce.

Effects of inner cone length on continuous rotating detonation in a variable cross-section combustor

A variable cross-section combustion chamber with different inner cone length L is designed, composing of an annular part with divergent width and a cylinder part without inner cone. Ethylene-air and hydrogen-air continuous rotating detonation (CRD) experimental tests are conducted. The results show that the ethylene-air CRD wave can be achieved in the variable cross-section combustor with the short inner cone. The propagation velocity of ethylene-air CRD wave can be 1661.37 m/s with the equivalence ratio of 0.91 and L of 10 mm. With L increasing from 0 mm to 30 mm, the combustion mode varies in the single wave mode, the sawtooth wave mode, and the hybrid mode. The combustor width is not the main factor leading to the failure of detonation in this study. The acceleration of propellent mixture caused by the expansion of the annulus channel, and the downstream movement and reduction of recirculation zone around the inner cone both increase the difficulty in CRD realization. While the hydrogen-air CRD can self-sustain with the intensive reaction zone in the annular part in the critical configuration of ethylene-air CRD. This study will contribute to the understandings of self-sustaining mechanism of CRD in the divergent combustor and the combustor design of the hollow chamber.

SCAPV Creates the Possibility of Less Irrigation and Higher Productivity

In agrivoltaic (APV), photovoltaic (PV) panels are positioned above farmland to produce energy and food simultaneously. However, PV panels above farmland block most sunlight from reaching plants for photosynthesis. Plants require sunlight for photosynthesis. We proposed Spectrum-splitting and Concentrated APV (SCAPV) to address contradictions between photosynthesis and energy production simultaneously. This study examines the effect of SCAPV on the evapotranspiration and growth of peanuts and soybeans. Peanuts and soybeans were planted under SCAPV and open-air (CK) treatments, and a weather station was placed in each treatment. Results showed that evapotranspiration under SCAPV significantly decreased by 31% compared to CK. Thus, it improved physiological characterization, enhanced quality, and increased the yield of peanuts and soybeans. Peanuts' protein, fat, and linoleic acid increased by 5.54%, 0.28%, and 1.14% under SCAPV compared to CK. Fat, soluble sugar, linoleic acid, and alpha-linolenic acid of soybean were increased by 6.75%, 15.24%, 13.72%, and 15.14%, respectively, under SCAPV compared to CK. The average land equivalent ratio of SCAPV is 1.7. We trust that SCAPV could provide food and energy while reducing irritation on the same farmland.

Research on Evaluation Indicators of AgriVoltaics

In recent years, with the popularization of environmental protection concepts and the continuous development of new energy technologies, agrivoltaics has attracted increasing attention and become an important direction of new agricultural development as a new type of agricultural planting method and new energy utilization method. This article classifies ground-based agrivoltaic schemes into three categories according to different management and distributions of solar radiation: intensity management, spectrum management, and time management. The article also details the performance of high-quality schemes proposed by our research team for these three categories. In addition, the article proposes four evaluation indicators for agrivoltaic schemes: land equivalent ratio (LER), return on investment (ROI), water-saving performance, and crop-friendliness, and calculates the performance of different schemes proposed by our research team based on these indicators. Finally, we recommend using these four dimensions to evaluate the performance of agrivoltaic schemes.

Parametric Study of Flow and Combustion Characteristic in a Cavitied Scramjet with Multi-Position Injection

This study focuses on the three-dimensional flow and combustion characteristics of a cavitied scramjet engine with multi-position injection. A single-equation large eddy simulation (LES) turbulence model is employed, with a detailed reaction mechanism for hydrogen combustion, as described by Jachimowski. The combustion characteristics of hydrogen in the scramjet combustion chamber are analyzed. Based on the combustion chamber model, the influence of different equivalence ratios, injection timing, injection positions, and injection pressures on the flame formation and propagation process are compared. The results indicate that within a certain range, an increase in the equivalence ratio enhances the combustion intensity and chamber pressure. In the case of multi-position injection, the order of injection from different nozzles has little effect on the final flame stabilization mode and pressure distribution. The opposite-side distribution of nozzles can effectively improve the fuel efficiency and the internal pressure. Furthermore, when the nozzles are closely placed in the opposite-side distribution, the combustion efficiency increases, although this leads to a higher total pressure loss. In scenarios where the fuel injection duration is short, an increase in the injection pressure at the upstream nozzles of the cavity results in a higher local equivalence ratio, as well as reduced fuel mixing and ignition time.

Composite patch with negative Poisson's ratio mimicking cardiac mechanical properties: Design, experiment and simulation

Developing patches that effectively merge intrinsic deformation characteristics of cardiac with superior tunable mechanical properties remains a crucial biomedical pursuit. Currently used traditional block-shaped or mesh patches, typically incorporating a positive Poisson's ratio, often fall short of matching the deformation characteristics of cardiac tissue satisfactorily, thus often diminishing their repairing capability. By introducing auxeticity into the cardiac patches, this study is trying to present a beneficial approach to address these shortcomings of the traditional patches. The patches, featuring the auxetic effect, offer unparalleled conformity to the cardiac complex mechanical challenges. Initially, scaffolds demonstrating the auxetic effect were designed by merging chiral rotation and concave angle units, followed by integrating scaffolds with a composite hydrogel through thermally triggering, ensuring excellent biocompatibility closely mirroring heart tissue. Tensile tests revealed that auxetic patches possessed superior elasticity and strain capacity exceeding cardiac tissue's physiological activity. Notably, Model III showed an equivalent modulus ratio and Poisson's ratio closely toward cardiac tissue, underscoring its outstanding mechanical potential as cardiac patches. Cyclic tensile loading tests demonstrated that Model III withstood continuous heartbeats, showcasing outstanding cyclic loading and recovery capabilities. Numerical simulations further elucidated the deformation and failure mechanisms of these patches, leading to an exploration of influence on mechanical properties with alternative design parameters, which enabled the customization of mechanical strength and Poisson's ratio. Therefore, this research presents substantial potential for designing cardiac auxetic patches that can emulate the deformation properties of cardiac tissue and possess adjustable mechanical parameters.

Maize/soybean intercropping increases nutrient uptake, crop yield and modifies soil physio-chemical characteristics and enzymatic activities in the subtropical humid region based in Southwest China

Intercropping, a widely adopted agricultural practice worldwide, aims to increase crop yield, enhance plant nutrient uptake, and optimize the utilization of natural resources, contributing to sustainable farming practices on a global scale. However, the underlying changes in soil physio-chemical characteristics and enzymatic activities, which contribute to crop yield and nutrient uptake in the intercropping systems are largely unknown. Consequently, a two-year (2021–2022) field experiment was conducted on the maize/soybean intercropping practices with/without nitrogen (N) fertilization (i.e., N0; 0 N kg ha−1 and N1; 225 N kg ha−1 for maize and 100 N kg ha−1 for soybean ) to know whether such cropping system can improve the nutrients uptake and crop yields, soil physio-chemical characteristics, and soil enzymes, which ultimately results in enhanced crop yield. The results revealed that maize intercropping treatments (i.e., N0MI and N1MI) had higher crop yield, biomass dry matter, and 1000-grain weight of maize than mono-cropping treatments (i.e., N0MM, and N1MM). Nonetheless, these parameters were optimized in N1MI treatments in both years. For instance, N1MI produced the maximum grain yield (10,105 and 11,705 kg ha−1), biomass dry matter (13,893 and 14,093 kg ha−1), and 1000-grain weight (420 and 449 g) of maize in the year 2021 and 2022, respectively. Conversely, soybean intercropping treatments (i.e., N0SI and N1SI) reduced such yield parameters for soybean. Also, the land equivalent ratio (LER) and land equivalent ratio for N fertilization (LERN) values were always greater than 1, showing the intercropping system’s benefits in terms of yield and improved resource usage. Moreover, maize intercropping treatments (i.e., N0MI and N1MI) and soybean intercropping treatments (i.e., N0SI and N1SI) significantly (p < 0.05) enhanced the nutrient uptake (i.e., N, P, K, Ca, Fe, and Zn) of maize and soybean, however, these nutrients uptakes were more prominent in N1MI and N1SI treatments of maize and soybean, respectively in both years (2021 and 2022) compared with their mono-cropping treatments. Similarly, maize-soybean intercropping treatments (i.e., N0MSI and N1MSI) significantly (p < 0.05) improved the soil-based N, P, K, NH4, NO3, and soil organic matter, but, reduced the soil pH. Such maize-soybean intercropping treatments also improved the soil enzymatic activities such as protease (PT), sucrose (SC), acid phosphatase (AP), urease (UE), and catalase (CT) activities. This indicates that maize-soybean intercropping could potentially contribute to higher and better crop yield, enhanced plant nutrient uptake, improved soil nutrient pool, physio-chemical characteristics, and related soil enzymatic activities. Thus, preferring intercropping to mono-cropping could be a preferable choice for ecologically viable agricultural development.

Cellular instabilities of expanding hydrogen-propane-nitrous oxide spherical flames: experiment and theory

The cellular instabilities of expanding hydrogen-propane-nitrous oxide spherical flames were experimentally and theoretically investigated at various equivalence ratios (ϕ=0.4-1.6), hydrogen fractions (XH=0-0.8), and initial pressures (Pu=1.1-1.5 bar). The experiments were conducted in a constant volume combustion chamber (CVCC) using high-speed schlieren technology to record the flame morphology, while the theoretical analysis was based on linear stability theory. The controlling parameters, critical conditions for the onset of instability, flame front oscillation intensity, logarithmic growth rate of perturbation, etc. were studied. The results indicate that the instability of premixed hydrogen-propane-nitrous oxide flames is dominated by hydrodynamic instability at XH≤0.6, while the competitive mechanism between thermal-diffusion and hydrodynamic instabilities is considered at XH=0.8. The oscillation intensity in the horizontal direction of the flame profile is more prominent than those in other directions, and with the increasing hydrogen fraction, the equivalence ratio at which the highest oscillation strength occurs shifts from ϕ=1.0 to ϕ=0.6. The trends of the experimental critical radius and Peclet number with each initial condition are completely identical to that of the theoretical value, but the experimental value is somewhat underpredicted. The three main reasons are proposed in the paper.Novelty and Significance Statement: This work is the first study on the cellular instabilities of hydrogen-propane-nitrous oxide flames by experiment and theory. It is under a small scale and reduced initial pressure condition that the cellular destabilization of hydrogen-propane flames is realized in the nitrous oxide atmosphere, while in the air atmosphere, the initial condition at which flame cellular destabilization occurs is harsher. Flame front oscillation strength, growth rate of disturbance, etc. were used to characterize quantitatively the degree of wrinkles and instabilities. Some novel findings were presented in the study. The present work is of great significance for the combustion community to understand deeply the cellular instabilities characteristic of expanding spherical flames supported by nitrous oxide, as well as for the engineering community to optimize the engine, propulsion, and energy supply systems, etc.

Forage yield, competition, and economic indices of oat and common vetch intercrops in a semi-arid region

Intercropping of annual favorable legumes with grains to produce forage is utilized extensively worldwide to improve resource use efficiency. To identify the best intercropping system for a semi-arid region of China, intercrops of oat (Avena sativa L.) and common vetch (Vicia sativa L.) at five planting proportions and oat and common vetch monocrops were produced over the 2011 and 2012 growing seasons in Xifeng, northwest China. Several indices were used to evaluate yields, competitive interrelationships between the two crops, and economic returns. The oat mono-crop had the highest dry matter yield (6.51 t ha−1), while the oat–common vetch intercrop, with an 80: 20 planting ratio, produced the highest crude protein production (696 kg ha−1). The land equivalent ratio (1.167), relative crowding coefficient (2.445), and actual yield loss (0.750) were more favorable for the oat–common vetch intercrop at a seeding ratio of 20: 80. The oat–common vetch intercrop at a seeding ratio of 20: 80 showed the highest values for monetary advantage index (35.51). Overall, the autumn-sown 20: 80 oat–common vetch intercrop was more productive from resource utilization and economic perspectives.

Fatally impaired glucose digestion by propylene glycol in Aedes aegypti (Diptera: Culicidae) and co-formulation with terpenoids for enhancing attractive toxic sugar baits.

Propylene glycol (PG) demonstrates greater efficacy than other sugar polyols. However, the attributes it confers for toxicity and possible co-formulation with other ingredients are unknown. To evaluate this, α-glucosidase and glucose oxidase reactions were performed in Aedes aegypti (L.) (Diptera: Culicidae) to categorize if PG behaves similarly to prior studied sugar alcohols. A combination of no-choice and choice assays was used to determine effective ratios of PG and sucrose, competitiveness against a control of 10% sucrose, and whether mosquitoes recovered from PG consumption. The final trials included β-cyclodextrin encapsulated cinnamon leaf oil, clove stem oil, patchouli oil, garlic oil, cedarwood oil, and papaya seed oil formulated with 5% sucrose + 5% PG. PG functioned as a linear competitive inhibitor of α-glucosidase. The efficacy of PG was synergized by co-ingestion with equivalent ratios of sucrose. Unlike the high diuretic response to other sugar alcohols, PG resulted in diminished excretion regardless of being co-formulated with sucrose or terpenoids. PG is not especially competitive against unadulterated sugar meals but is likewise not clearly repellent. Although mosquitoes did not recover from ingestion of the glycol meals, there was no indication that mortality would continue to accumulate once the treatments were removed. Of the terpenoids tested, cinnamon and patchouli caused ~50% or less mortality; garlic, cedarwood, and clove caused 80-90% mortality; and papaya seed caused 100% mortality, exceeding all other test groups and the formulation blank. PG is a useful supporting ingredient in attractive toxic sugar bait formulations with flexibility in formulation.

Experimental Investigation of Solid Rocket Scramjet Based on Central Strut

Scramjet based on solid propellant has become a potential choice for the development of future hypersonic vehicles. In this paper, a boron-containing solid rocket scramjet based on the central strut injection was proposed, and the ground direct-connect experiment with the equivalence ratios of 0.43 to 2.4 under the flight condition of Mach 6, 25 km was carried out. The pressure and flow rate over time were measured in the experiment. The results show that the engine can realize stable supersonic mode or subsonic mode combustion by changing the gas flow rate. The engine can effectively increase the combustor pressure, reduce the unstable combustion time, and advance the strong combustion position by increasing the gas flow rate. The engine achieved high combustion efficiency when the equivalence ratio was about 1, with a maximum of 88.28%. A numerical simulation analysis was also carried out in this paper. Compared to the experimental results, the pressure error obtained by numerical simulation was less than 4%, and the typical position error was less than 3%, suggesting that the simulation model can be used to predict the behavior of scramjet.

On the Chemical Effect of Steam Addition to Premixed Hydrogen Flames with Respect to $$\text {NO}_\text {x}$$ Emissions and Flame Speed

AbstractThe present work analyses the effect of water vapour addition on $${\text {NO}_\text {x}}$$ NO x emissions of premixed hydrogen flames. In doing so, the adiabatic flame temperature is maintained by increasing the equivalence ratio, or alternatively increasing the unburned gas temperature, for increasing levels of water loading. Thus, it is possible to elucidate the changes in $${\text {NO}_\text {x}}$$ NO x production at constant-temperature conditions when the mixture is diluted with water. A consistent reduction of $${\text {NO}_\text {x}}$$ NO x emissions for increasing water dilution can be observed from 1-D premixed freely propagating flame simulations. Regarding the chemical kinetics effect of water vapour, the relative importance of different third-body reactions is examined by modifying the corresponding water collision efficiencies individually. For the chemical mechanism adopted, three reactions directly affect the nitrogen chemistry and the remaining relevant reactions are important for the flame structure and radicals concentration. The analysis stresses the importance of indirect effects like the formation and consumption of $$\text {O}$$ O and $$\text {H}$$ H radicals in the pre-heat zone, which enhance the subsequent formation of $${\text {NO}_\text {x}}$$ NO x within the flame. The presence of steam can lead to a reduction of approximately $$50\%$$ 50 % in $${\text {NO}_\text {x}}$$ NO x emissions under conditions close to stoichiometry and high water loading ($$10\%$$ 10 % by mass), compared to scenarios without water addition. Furthermore, the efficiency of water in third-body reactions significantly contributes to an emission reduction, and half of $$\text {NO}$$ NO emissions under the same water loading conditions at high equivalence ratio are observed when the third-body reaction efficiency is activated with respect to the case with zero efficiency. This reduction is primarily attributed to effects on radical concentrations. Finally, the chemical effect via the third-body efficiency of water is examined with respect to flame speed. It turns out that the adiabatic flame temperature plays a key role for the relative influence of the chemical kinetics effect of water dilution. A cross-over temperature is found, below which the chemical effect of water reduces the flame speed, whereas the flame speed is increased above it.

Effect of Ethanol and Iso-Octane Blends on Isolated Low-Temperature Heat Release in a Spark Ignition Engine

&lt;div&gt;Low-temperature heat release (LTHR) is of interest for its potential to help control autoignition in advanced compression ignition (ACI) engines and mitigate knock in spark ignition (SI) engines. Previous studies have identified and investigated LTHR in both ACI and SI engines before the main high-temperature heat release (HTHR) event and, more recently, LTHR in isolation has been demonstrated in SI engines by appropriately curating the in-cylinder thermal state during compression and disabling the spark discharge. Ethanol is an increasingly common component of market fuel blends, owing to its renewable sources. In this work, the effect of adding ethanol to iso-octane (2,2,4-trimethylpentane) blends on their LTHR behavior is demonstrated. Tests were run on a motored single-cylinder engine elevated inlet air temperatures and pressures were adjusted to realize LTHR from blends of iso-octane and ethanol without entering the HTHR regime. The blends were tested with inlet temperatures of 40°C–140°C at equivalence ratios of 0.5, 0.67, and 1.0 with boosted (1.5 barA) conditions. The measured LTHR decreased with increasing ethanol content for all conditions tested; iso-octane–ethanol blends with above 20% ethanol content (by volume) showed minimal LTHR under engine conditions. These net effects resulted from the combination of thermal effects (charge cooling) and chemical effects (reactivity changes at low temperatures). The effect of temperature, pressure, fuel composition, and equivalence ratio on ignition delay times calculated from chemical kinetic modeling are presented alongside pressure–temperature trajectories of the in-cylinder gases to explain the trends. The underlying cause of the trends is explained by using a sensitivity analysis to determine the contribution of each reaction within the chemical kinetic mechanism to first-stage ignition, revealing the effect of introducing ethanol on the OH radical pool and resulting LTHR intensity.&lt;/div&gt;

The Impacts of Planting Patterns Combined with Irrigation Management Practices on Watermelon Growth, Photosynthesis, and Yield.

(1) Background: Crop yields in China's arid and semi-arid regions are limited by water shortages. Exploring the interactions and resource utilization among agroforestry species is key to maintaining diversified agricultural production. (2) Objective: An apple-watermelon agroforestry system and watermelon sole-cropping system were compared to quantify how resource availability (light, water) and watermelon performance (leaf photosynthetic rate, growth, and yield) change with irrigation strategies. (3) Methods: A three-year apple and watermelon field experiment was conducted in a young apple orchard in the arid area of central Ningxia to test the effect of light competition and irrigation systems on light environment, leaf photosynthetic rate, plant growth, and yield in watermelon. The experiment encompassed two planting patterns: (i) apple-watermelon agroforestry (AF) and watermelon sole-cropping (SC) and (ii) three irrigation quotas (W1: 105 mm, W2: 210 mm, and W3: 315 mm). (4) Results: The results show that the agroforestry planting pattern extended the growth period of watermelon and increased the leaf area index. Mean daily shade intensity increased by 16.02% from 2020 to 2022. The land equivalent ratio (LER) was >1 in 2021 and 2022. The SWC, leaf photosynthetic rate, LAI, and yield of watermelon in an agroforestry planting pattern were lower than when in a sole-cropping planting pattern. However, under the W1 irrigation strategy, the total soluble solids of the agroforestry planting pattern were 2.27% higher than those of the sole-cropping pattern, and the yield of the agroforestry planting pattern was 2.59% higher than that of the sole-cropping pattern. Under the W3 irrigation strategy, the average watermelon weight in the agroforestry planting pattern was 2.85% higher than that of the sole-cropping pattern. A path analysis showed that the agroforestry planting pattern can increase the yield by increasing soil water content, which is different from the sole-cropping pattern. (5) Conclusions: The results confirm that the apple-watermelon agroforestry planting pattern reduced watermelon yields. However, the LER of the agroforestry system was greater than 1.0. It is reasonable to plant watermelons in young apple forests.