Energy Ratio Research Articles

Theory of Electron Transport in Two-Barrier Five-Layer Semiconductor Structures

The dependence of the transparency coefficient of a five-layer two-barrier structure on the electron energy and the ratio of the widths of two neighboring potential barriers is calculated. It is shown that the extremum of the transparency coefficient significantly depends on the geometric dimensions of the structure layers. In a symmetric five-layer two-barrier semiconductor structure, the condition for the occurrence of "resonant" electron transitions is defined. It is demonstrated that the mechanism of such (resonant) transitions is explained by the interference of de Broglie waves of electrons in the potential well, where the phases of de Broglie waves are determined by the geometric dimensions of the structure, and their amplitudes - by the ratio of the carrier energy to the height of the potential barrier. It has been established that with an increase in the effective mass of charge carriers, the number of intersections of the quantities fR (ξ) and ((1-2ξ))/(√(ξ-ξ2) increases. These intersections determine the dimensionally-quantized levels where electrons are localized.

Effect of fluid flow behavior on sustainability and exergy efficiency of solar heat collectors having multiple V‐ribs with gaps

AbstractIn the current numerical study, the viability and sustainability of a solar heat collector (SHC) have been rigorously analyzed through the lens of exergy analysis. The SHC with roughness in the form of symmetrical V‐rib gaps has been selected for detailed numerical investigation. The study focuses on deriving the dominant parameters affecting the performance of the SHC, including the relative gap width (), number of gaps () in the limbs of ribs, and fluid flow Reynolds number, which varied from 4000 to 18,000. The absorber plate with roughness was thoroughly examined to evaluate the losses and irreversibility that persist in the thermal system. The results of the numerical analysis revealed the maximum exergy efficiency to be 3.87%. Furthermore, the study examined the long‐term feasibility of the system, evaluating its sustainability index at a remarkable 1.0319 value, while the magnitude of the waste–energy ratio fetched an impressive score of 0.991. Additionally, the study found that the system has a significant improvement potential of 10.04. Overall, these findings provide critical insights into the performance and sustainability of SHCs, paving the way for future research and development in this crucial field.

444 The effects of increasing standardized ileal digestible lysine-to-net energy ratio during at 24-day lactation period on primiparous sow nitrogen utilization and lactation performance

444 The effects of increasing standardized ileal digestible lysine-to-net energy ratio during at 24-day lactation period on primiparous sow nitrogen utilization and lactation performance

Source-independent Q-compensated viscoacoustic least-squares reverse time migration

The strong viscosity of the subsurface introduces amplitude absorption and phase-velocity dispersion. Incorrect compensation of the inherent attenuation (the strength of the seismic attenuation can be quantified by the inverse of the quality factor Q, which is defined as [Formula: see text] times the ratio of the stored energy to the lost energy in a single cycle of deformation) can significantly affect imaging quality. Although Q-least-squares reverse time migration ( Q-LSRTM) allows for the compensation of attenuation effects during the iterations, the traditional [Formula: see text]-norm minimization, which is highly sensitive to the source wavelet, poses a challenge in accurately estimating the source wavelet from the field data. Thus, we develop a source-independent Q-LSRTM, in which a convolutional objective function is introduced to replace the [Formula: see text]-norm constraint to mitigate the source wavelet effect. According to the Born approximation, we first linearize the constant-order decoupled fractional Laplacian viscoacoustic wave equation to derive the demigration operator and then construct the corresponding adjoint equation and gradient based on the convolutional objective function, iteratively estimating the reflectivity images. Our method relaxes the sensitivity to the wavelet compared with the conventional [Formula: see text]-norm scheme due to the convolutional objective function, which has the ability to construct the same new source for simulated and observed data. Numerical tests on a layered model, the Marmousi model, and field data demonstrate that our source-independent Q-LSRTM enables us to obtain high-quality reflectivity images even when using incorrect source wavelets.

Modeling the melting temperature of semiconductor nanocrystals

Exploring the thermal stability of semiconductor crystals at the nanoscale is of great significance for the design, fabrication, and application of modern quantum devices. In this paper, we propose a thermodynamic model to predict the melting temperature of semiconductor nanocrystals, which is in good agreement with the experimental results of Si, Bi, CdS, and CdSe. In addition, when the size decreases, the drop of melting temperature curves tends to be synchronized with the size-dependent solid/liquid interface energy and surface stress ratio γsl(D)/f(D), which reveals the physical origin of the decrease in the melting temperature of the semiconductor nanocrystals.

Numerical study on the polarity change process during internal wave shoaling

Polarity change is an important mechanism for internal waves shoaling. In this study, a numerical model for simulating the real-scale internal wave passing over slope-shelf topography is established based on the Fourier pseudo-spectral method and weakly nonlinear theory. By numerical simulation, the effects of shelf height, initial wave amplitude, and inclination angle on the waveform characteristics and energy properties of the internal wave during its shoaling are investigated. In the polarity change process, the initial internal wave converts into a depression wave and a generated elevation wave behind it. The distance between the peak of the elevation wave and the trough of the depression wave is a key feature to describe the polarity change. In terms of energy properties, the energy ratio of depression and generated elevation waves compared with the initial wave as well as their relative magnitude is mainly determined by the shelf height. In addition, the initial wave amplitude also affects the generation of the elevation wave and the attenuation of the depression wave to a certain extent. The increase in the inclination angle hinders the formation of the elevation wave but has little effect on the depression wave energy.

Chemical kinetic study of methane blended with ammonia cracked gas at elevated temperature and pressure

Ammonia (NH3) on-line cracking to produce hydrogen (H2) can avoid direct ammonia combustion and is an important method to enhance combustion performance and control nitrogen oxide (NOx) emissions. This work aims to study the effects of various ammonia energy ratios (ENH3) and cracking ratios (CNH3) on the combustion and NO emission characteristics of methane (CH4) blended with ammonia cracked gas under lean-burn condition. The results showed that methane co-combustion and ammonia cracking significantly enhance the laminar burning velocity (LBV). The chemical effect plays a dominant role in the enhancement of LBV, but its relative contribution gradually decreases with increasing ENH3 and CNH3. A linear relationship between LBV and (O+H+OH+NH2 + CH3)max was observed, with both the slope and intercept being functions of CNH3. At an ENH3 of 20 %, NO emission decrease with increasing CNH3. At an ENH3 of 80 %, NO emission first increase and then decrease. The percentage of thermal NO is less than 1 % under ambient condition and could increase to as much as 22 % under elevated condition (500 K, 10 atm). Additionally, there was a quadratic polynomial relationship between (O+H+OH+NH2)max and the final NO mole fraction within an equivalence ratio range from 0.4 to 0.8. The second-order coefficient exhibits a linear correlation with CNH3, while the first-order and constant coefficient show a quadratic polynomial correlation with CNH3.

Optimal design and techno-economic analysis of a solar-wind hybrid power system for laayoune city electrification with hydrogen and batteries as a storage device

The pressing environmental concerns associated with fossil fuels have propelled renewable energy sources, particularly solar and wind energy, into a more prominent position. This article aims to explore an optimal configuration and conduct a technical and economic analysis of a hybrid solar-wind energy system tailored for electrifying Laayoune city. This system, equipped with hydrogen tank and batteries as storage devices, aims to meet the annual energy requirements of residential areas estimated at 310.87 GWh/year. In addition to addressing energy needs, the study tackles significant challenges such as reducing dependence on traditional energy sources, curbing greenhouse gas emissions, and bolstering energy security in the region. Utilizing HOMER Pro software, the research evaluates various combinations of renewable resources, including solar and wind, alongside storage solutions such as batteries, fuel cells, and hydrogen storage, to find the most viable solution in terms of electricity generation, cost, and environmental impact. The findings highlight a hybrid configuration comprising solar, wind, battery, grid, and converter components as the most cost-effective approach for Laayoune's renewable energy system. This integrated system not only yields an energy cost of 0.0477 $/kWh and a net present cost (NPC) of 336 M$ but also generates 627.69 GWh/year of energy. Furthermore, it achieves a 100% renewable energy ratio while completely eliminating CO2 emissions.

Optimization of energy efficiency in gas production from hydrates assisted by geothermal energy enriched in the deep gas

Scaled-up production from natural gas hydrates is still facing the significant issues of limited gas yield and unsustainable hydrate dissociation. In this work, the deep gas with huge reserves and abundant geothermal energy was used to enhance the hydrate production efficiency. Results showed that the geotherm-assisted gas production was significantly increased by 178.22 %. Surprisingly, the hydrate dissociation rate was slightly weakened by 3.66 % due to the hindered fugacity of the gas from hydrate decomposition as a result of the fast deep gas upwelling. Besides, the energy flow analysis showed that up to 40.67 % of the deep gas injection energy was dissipated to the surroundings, with only 8.28 % utilized for the hydrate decomposition. Consequently, the multi-well deployment was used to regulate the deep gas injection rate. It was found that the multiple wells weakened the sealing effect of hydrate on migration channels, preventing the violent gas upwelling while increasing the hydrate decomposition amount under geothermal stimulation. Then, prolonging crossflow distance of deep gas in the hydrate layer enabled the sediment to absorb more injected energy, resulting in the minimum wasted energy ratio. Not limited to this, the more stable gas production throughout the whole process effectively guaranteed the safety of exploitation. Finally, the hydrate decomposition rate in the depressurization and constant pressure stages was found to be positively correlated with the utilization ratio of the injected energy and the injected rate, respectively. The results could help guide the formulation of the multi-gas joint production scenarios in the field tests to balance production efficiency and cost.

Effects of ammonia energy ratio and PODE injection timing on combustion and emissions in a PODE/ammonia RCCI engine

The application of ammonia as an alternative carbon-free fuel has attracted increasing attention. In this paper, the effects and mechanisms of ammonia energy ratio (AER) and polyoxymethylene dimethyl ethers (PODE) injection timing on the combustion and emissions characteristics of a PODE/ammonia RCCI engine are investigated by both experimental and numerical methods. Results show that increasing AER from 10% to 40% leads to the delayed low temperature heat release (LTHR) due to reduced OH radical generated by PODE and the competition between PODE and ammonia for OH radical consumption. The larger AER increases the indicated thermal efficiency (ITE) by lowering combustion temperature and reducing heat transfer losses at the cost of higher hydrocarbon (HC), carbon monoxide (CO), and unburned NH3 emissions. The reduction of fuel-based nitrogen oxide (NOx) emissions with a larger AER is attributed to the enhanced in-cylinder thermal denitrification reactions. The delayed start of injection (SOI) from −60 °CA ATDC to −45 °CA ATDC leads to the higher peak in-cylinder pressure and temperature, resulting in the larger heat transfer losses and lower ITE. The impact of retarding SOI on NOx is insignificant under the combined effect of more thermal NO formation, less fuel-based NO generation, and weakened denitrification reactions. Additionally, nitrous oxide (N2O) shows dominant effects on the total greenhouse gas (GHG) emissions, and increasing AER or advancing injection timing produces more GHG. Under low loads and low AERs, although the introduction of ammonia helps to improve ITE, more researches are required to further reduce exhaust emissions.

Experimental study on ignition and flame propagation of premixed ammonia ignited by Direct-Injected diesel in an optical rapid compression Machine

Ammonia (NH3) is considered as one of the most promising zero-carbon fuels for internal combustion engines. Based on diesel engine modification, The ammonia/diesel dual-fuel mode with port injection of ammonia and in-cylinder direct injection of diesel has been proven to be the most feasible strategy. In this paper, the effects of ignition and flame propagation of premixed ammonia ignited by direct-injected diesel were studied based on an optical rapid compression machine (RCM). The results show that the spray and distribution of diesel play the key role in the ignition and flame propagation of NH3/diesel dual fuels combustion. For total excess air ratio (λT) of 1.0, the ignition delay of NH3/diesel with high energy ratio of ammonia (ER of 95 %) was much shorter than ER of 66 % which was mainly due to the low injection pressure of diesel. Under the same injection pressure, with the large nozzle diameter of diesel injector of 0.28 mm, the ignition delay of NH3/diesel will be shortened significantly. When the ER is low, the combustion process presents the characteristics similar to the multi-point compression combustion. When the ER rises to 83 %, the combustion process is mainly dominated by NH3 premixed combustion, and diesel mainly plays the role of ignition. Reducing the background pressure and temperature to 4 MPa and 887 K, respectively, NH3 is not able to be ignited by diesel.

An energy and information analysis method of logic gates based on stochastic thermodynamics.

To reduce the energy consumption of logic gates in digital circuits, the size of transistors approaches the mesoscopic scale, e.g. sub-7 nanometers. However, existing energy consumption analysis methods exhibit various deviation for logic gates when the nonequilibrium information processing of mesoscopic scale transistors with ultra-low voltages is analyzed. Based on the stochastic thermodynamics theory, an information energy ratio method is proposed for the energy consumption estimation of XOR gates composed of mesoscopic scale transistors. The proposed method provides a new insight to quantify the transformation between the information capacity and energy consumption for XOR gates and extending to other logic gates. Utilizing the proposed analysis method, the supply voltage of the parity check circuit can be optimized by numerical simulations without expensive and complex practical measurements. The information energy ratio is the first analytical method to quantify the energy and information transformation of logic gates at the mesoscopic scale.

Experimental study on combustion and emissions of an ammonia/diesel dual-fuel engine using split-injection strategy

Blending high-reactivity fuels is recognized as an effective way to improve poor combustion performance of ammonia (NH3). In this work, pressure trajectories, flame evolutions, and emission characteristics of ammonia/n-dodecane dual fuels were studied in an optical engine, addressing split-injection strategy. Synchronization measurement of in-cylinder pressure and high-speed photography was performed for combustion evolutions, and FT-IR spectroscopy was adopted for nitrogen-based emissions. Results demonstrate that pre-injection timing and its energy ratio play a significant role in improving engine thermal efficiency and pollution emissions. Specifically, compared to the single-injection strategy, split-injection strategy leads to a reduced peak in-cylinder pressure, optimized combustion phasing, and shortened combustion duration, achieving an increase in the indicated mean effective pressure by 15.8 %. An early pre-injection timing with an energy ratio of 40 %∼60 % yields superior thermal efficiency compared to single injection at the same injection timing. For the delayed pre-injection timing, increasing pre-injection energy ratio is required to achieve optimal engine performance. Combustion visualizations show that the improved flame development under split-injection conditions is attributed to high-reactivity fuel stratification and enhanced premixing processes. Regarding nitrogen-based emissions, unburned NH3 and N2O emissions are insignificantly reduced, and NOx emissions correlate with the sensitivity of flame development to in-cylinder temperature. On the premise of ensuring stable combustion, all nitrogen-based emissions are reduced at a pre-injection energy ratio of 40 %, and an energy ratio of 60 % reduces N2O and unburned NH3 emissions while increasing NO and NO2 emissions. The current work can provide useful insights into the optimization and control of ammonia/diesel dual-fuel engines in terms of combustion and emissions.

Simulation of biocrude production from P. tricornutum, S. platensis, and C. vulgaris using Aspenplus®

Hydrothermal liquefaction (HTL) of biomass is performed at elevated pressure and temperature to avoid the drying process. This process is also suitable for the low grade biomass with higher moisture content. In this article, simulation of three types of microalgae species, such as Phaeodactylum tricornutum, Spirulina platensis, and Chlorella vulgaris, are performed using Aspen Plus®. Simulation conditions, for instance, temperature, proximate and ultimate analyses, feed rate, water content, component names, etc., are taken from the literatures. The results of microalgae are then compared at two different temperature conditions. The values, however, are not the same for all the materials due to the data availability from the literature. The highest calorific value is obtained from C. vulgaris; it is 37.27 MJ/kg at 621K, and the highest energy recovery and energy ratio are obtained from P. tricornutum; they are 88.78 % and 1.86, both at 648K respectively. The difference between experimental and simulated calorific values of different biocrudes are ranging from 2.7 % to 3.62 % at higher temperatures and from 4.68 % to 10.72 % at lower temperatures. Finally, it is found that the simulation results corroborate with the experimental results with minimal errors.

Study of [formula omitted]/EC-decay properties of [formula omitted] shell nuclei using nuclear shell model

Our study employs the nuclear shell model to systematically compute the half-lives of β-decay for nuclei in the mass range of A=18−39, encompassing the majority of sd shell nuclei. This analysis utilizes the USDB and SDNN Hamiltonians. The theoretical outcomes contain calculations of various parameters such as Q-values, half-lives, excitation energy, logft values, and branching ratios. We explore these results with axial–vector coupling constant for weak interactions, denoted as gA(=1.27), and κ value (=6289). We perform calculations of Gamow Teller matrix elements for 116 decay processes to calculate the quenching factor; we found a quenching factor of q=0.794±0.05 for the USDB interaction and q=0.815±0.04 for the SDNN interaction. We have also calculated superallowed transitions 0+→0+ for seven nuclei. Further, we have also included the electron capture phase space factor for the required nuclei to calculate the half-lives. This inclusion leads to small contribution in results, particularly for nuclei where electron capture (EC) plays a significant role. The overall results are in agreement with the experimental data.

Effect of potassium persulphate-induced microwave pretreatment for cost-effective sludge solubilization and bioenergy recovery

The disintegration of municipal waste activated sludge (MWAS) by energy-intensive physical pretreatments is considered expensive. In the present study, an effort was undertaken to disintegrate the sludge by microwave assisted pretreatment (MAP) in an energy-efficient and economical way by combining the microwave with oxidant potassium persulphate. Besides, the sulphate radicals generated through activated persulfate can efficiently disintegrate and solubilize sludge. In this context, microwave pretreatment was combined with potassium persulfate to activate the generation of sulphate radicals for economically enhanced sludge solubilization. MAP was done by varying the microwave power levels (10 to 50 %) and pretreatment time (0 to 30 min). Microwave assisted potassium persulphate pretreatment (MAPPP) was done by varying the potassium per sulphate dosage (0.005 to 0.04 g/g Total solids (TS) and pretreatment time (0 to 14 min). Combining microwave with potassium persulfate brings about a synergistic effect, generating sulphate and hydroxyl radicals that can effectively disintegrate and solubilize biopolymers of sludge. A higher sludge lysis rate of 37.25 % was achieved by this microwave assisted potassium persulfate pretreatment (MAPPP) when compared to microwave assisted pretreatment (MAP) alone (26.27 % after thickening). A higher methane yield of 219.14 mL/g Volatile solids (VS) was obtained through MAPPP compared to MAP (154.22 mL/g VS). The detailed mass, energy, and economic assessment at a large-scale level for MAP and MAPPP revealed that MAPPP was energetically and economically feasible with an energy ratio of 1.22 and net profit of 42.03 USD/Ton compared to MAP. Thus, it can be confirmed that MAPPP was economically viable to implement on a large scale.

Anomalous hot electron generation from two-plasmon decay instability driven by broadband laser pulses with intensity modulations

We investigate the hot electrons generated from two-plasmon decay (TPD) instability driven by laser pulses with intensity modulated by a frequency Δω m using theoretical and numerical approaches. Our primary focus lies on scenarios where Δω m is on the same order of the TPD growth rate γ 0 ( Δωm∼γ0 ), corresponding to moderate laser frequency bandwidths for TPD mitigation. With Δω m conveniently modeled by a basic two-color scheme of the laser wave fields in fully-kinetic particle-in-cell simulations, we demonstrate that the energies of TPD modes and hot electrons exhibit intermittent evolution at the frequency Δω m , particularly when Δωm∼γ0 . With the dynamic TPD behavior, the overall ratio of hot electron energy to the incident laser energy, fhot , changes significantly with Δω m . While fhot drops notably with increasing Δω m at large Δω m limit as expected, it goes anomalously beyond the hot electron energy ratio for a single-frequency incident laser pulse with the same average intensity when Δω m falls below a specific threshold frequency Δω c . This anomaly arises from the pronounced sensitivity of fhot to variations in laser intensity. We find this threshold frequency Δω c primarily depends on γ 0 and the collisional damping rate of plasma waves, with relatively lower sensitivity to the density scale length. We develop a scaling model characterizing the relation of Δω c and laser plasma conditions, enabling the potential extention of our findings to more complex and realistic scenarios.

Integrated nutrient management on oat + grasspea intercropping system: an evaluation of system productivity, economics, energetics and carbon footprint

A field investigation took place at Central Research Farm of Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India during winter seasons of 2020–21 and 2021–22 with the aim to evaluate system productivity, economics, energetics and carbon footprint (CF) of oat + grasspea intercropping systems under different integrated nutrient managements (INM). The experiment was executed in split-plot design with 4 cropping systems in main plots and 4 levels of nutrient management in sub plots. The 3:3 intercropping system of oat + grasspea ensured highest system productivity, whereas sole grasspea stood best in terms of economics, energetics and environment safety by lowering CF. Notably, INM involving 75% N through urea + 25% N through vermicompost registered significantly higher system productivity in case of 3:3 oat + grasspea intercropping system (CS4N3) (18.77 q ha−1). Further, this intercropping system yielded high economic profitability (net return: US$ 430.4 ha−1, benefit–cost ratio: 1.71) as well as energy indices (energy output: 71179.1 MJ ha-1, net energy gain: 60352.0 MJ ha−1, energy ratio: 6.57 and energy profitability: 5.57). CF was also found relatively low under CS4N3 (Yield scaled CF: 62.2 kg CO2-e q−1). Furthermore, high carbon efficiency (7.92) and carbon sustainability index (6.92) were also exhibited by CS4N3 as it produced maximum carbon output (1801.2 kg ha−1). In conclusion, the 3:3 oat + grasspea intercropping system using INM can be viable option to ensure economic and energy viability and minimize greenhouse gas emissions without compromising system productivity. Particularly, this intercropping system combined with 75% N through urea + 25% N through vermicompost as INM option can be recommended for the cereal and legume growers of India, specifically under intensive cropping scenario.

Investigating corrosion-induced deterioration in bolted steel plate joints using guided wave ultrasonic inspection

AbstractBolted steel plate joints encounter challenges posed by joint corrosion, which impact the quality of interfacial contact among the bolted components. Unfortunately, no correlation between corrosion-induced joint damage and preload, nor an existing numerical model capable of capturing such effects, has been identified. This study aims to utilize guided wave ultrasonic investigation to examine the deterioration of interfacial contact caused by corrosion in bolted joints. Additionally, a contact modification-based numerical approach is presented to capture the effects of changing interfacial stress during joint corrosion. Guided wave mode selection was conducted with some preliminary experiments supplemented with the theory of wave mode dispersion, hence leading to the selection of S0 and A0 mode existing at 300 kHz. The joint was then corroded in a controlled manner using an electrochemical process while simultaneous ultrasonic measurements were taken. The experimental observations highlighted the progressive dispersion in the transmitted A0 mode across the bolted joint, potentially due to changing interfacial stress boundaries between the plates. A damage parameter, termed the dispersion index, was developed based on the energy ratio of different signal sections. A linear change in the dispersion index was observed with the increase in corrosion-induced mass loss. The insight was further established through a numerical investigation by studying the effect of changing bolt preload and the corresponding interfacial stress distribution. The findings revealed that monitoring the changes in the stress distribution at the bolted interface can provide insight into interfacial corrosion. Eventually, destructive tension test results confirmed the effect of joint corrosion on the load-bearing capacity of the joint. The change in failure mode of the pristine and corroded specimen is observed. The reported approach establishes the potential of ultrasonic inspection to investigate the interfacial health of a bolted joint in corroding conditions.

Probiotic‐rich bean sprouts alleviate oxidative stress and inflammation induced by a diet with an increased fat‐to‐carbohydrate energy ratio

SummaryThe rat's model evaluated the function of sprouted beans enriched with probiotic Lactiplantibacillus plantarum 299v in alleviating dyslipidaemia, inflammation and disturbed redox homeostasis caused by a high‐lard diet. Sprouted beans improved the total antioxidant capacity of serum and liver, regardless of whether the feeds had a higher content of low‐molecular antioxidants or were additionally enriched with probiotics. The reduction of inflammation (lowered level of C‐reactive protein) and restoration of triglycerides and total cholesterol to the levels recorded in the control group (AIN‐93M) were especially observed in the group supplemented with the control adzuki bean. Introducing sprouted legumes (both the control and probiotic‐rich) improved microbiota activity affected by a high‐lard diet. The highest, desirable reduction of urease (by 80%) and tryptophanase (by 78%) activity was found in the groups fed with probiotic‐rich adzuki and mung bean sprouts respectively. Sprouted beans improve the metabolism of individuals subjected to a diet with an increased fat‐to‐carbohydrate energy ratio, especially concerning oxidative stress injury and microbiota activity.