Maximum Energy Research Articles

Global Optimization and Quantitative Assessment of Large-Scale Renewables-Based Hydrogen System Considering Various Transportation Modes and Multi-Field Hydrogen Loads

In the past, hydrogen was mostly produced from fossil fuels, causing a certain degree of energy and environmental problems. With the development of low-carbon energy systems, renewable energy hydrogen production technology has developed rapidly and become one of the focuses of research in recent years. However, the existing work is still limited by small-scale hydrogen production systems, and there is a lack of comprehensive research on the whole production-storage-transportation-utilization hydrogen system (PSTUH2S), especially on the modeling of different hydrogen transportation modes and various hydrogen loads in different fields. To make up for these deficiencies, the specific physical and mathematical models of the PSTUH2S are firstly described in this paper, with a full account of large-scale water-electrolytic hydrogen production from renewable power curtailment and grid power, various hydrogen storage and transportation modes, and multi-field hydrogen consumption paths. Furthermore, to achieve the maximum economic, energy, and environmental benefits from the PSTUH2S, a multi-objective nonlinear optimization model is also presented herein and then solved by the hybrid method combining the nonlinear processing method, the CPLEX solver and the piecewise time series production simulation method. Lastly, case studies are conducted against the background of a region in northwest China, where hydrogen consumption capacity in various years is accurately assessed and the potential advantages of the PSTUH2S are demonstrated. As the simulation results show, the power curtailment of renewable energy generation can be reduced by 3.61/11.87/14.72 billion kW·h in 2025/2030/2035, respectively, thus contributing to a 4.98%~10.09% increase in the renewable energy consumption rate and millions of tons of carbon emission reduction in these years. In terms of the total equivalent economic benefits, the proposed method is able to bring about a cost saving of USD 190.44 million, USD 634.66 million, and USD 865.87 million for 2025, 2030, and 2035, respectively.

In-situ growth of novel iron oxide/iron organic framework composites as efficient electroactive materials of battery supercapacitor hybrids

Iron oxide (Fe2O3) with a high theoretical capacitance, wide potential ranges and easy availability has attracted much attentions as the electrode material of battery supercapacitor hybrids (BSH). Metal–organic framework (MOF) is one of the promising potential energy storage materials due to its large surface area and controllable pore structures. In this work, novel iron oxide/iron organic framework composites (Fe2O3/FeMOF) are in-situ grown on the Ni foam as efficient energy storage electrodes of BSH. By tuning the solvothermal durations, the morphology changes from random sizes of sheets, regular grown vertical sheets, to flower-like structures. The d-spacing also increases for the Fe2O3/FeMOF synthesized using longer solvothermal durations. The optimal Fe2O3/FeMOF electrode synthesized using 9 h shows a high areal capacitance of 10.97 F/cm2 along with an areal capacity of 5.49 F/cm2 at the current density of 35 mA/cm2, owing to the most regular growth of sheets, the large d-spacing, and the smallest charge-transfer resistances. A BSH composed of the Fe2O3/FeMOF positive electrode and a graphene negative electrode shows a maximum energy density of 0.76 mWh/cm2 at 22.5 mW/cm2. The excellent long-term cycling stability with the capacitance retention of 85% and Coulombic efficiency of 98% are also achieved after 10,000 charge/discharge cycles.

Cooperative interference to achieve interval many-objective evolutionary algorithm for association privacy secure computing migration

In this paper, we study secure computing migration scenarios in uncertain environments with the presence of multiple malicious eavesdroppers (MEs). Specifically, when edge servers (ESs) execute tasks delivered by smart devices (SDs), SDs may move beyond the coverage of ESs, and computing migration (CM) of unfinished tasks is required to ensure service continuity. There is a risk of privacy leakage during task migration, and MEs use colluding eavesdropping to eavesdrop on the migrated tasks, and we consider eavesdropping on the associated tasks through data sharing among MEs to improve the eavesdropping efficiency. For eavesdropping in MEs, we achieve eavesdropping strikes using cooperative interference by jammers, which benefit by providing jamming services. In addition, uncertain computational scenarios directly affect the efficiency of task execution, and we consider the uncertainty factor in the malicious eavesdropping environment. To this end, this paper proposes the secure computational migration of associative privacy in uncertain environments (SCMAPUE) model, which transforms uncertainties into interval parameters, and optimizes the five objectives of migration delay, maximum completion time, energy consumption, load balancing and migration reliability to achieve efficient task execution and reliable migration. Aiming at the model characteristics, this paper designs an interval many-objective evolutionary algorithm for reliable migration (IMaOEA-RM), which employs a condition-based interval confidence strategy and a multi-access secure migration selection strategy to improve the convergence of the algorithm, and utilizes a dual-migration crossover strategy in order to adjust the jammer partners and improve the population diversity. Simulation results show that our proposed IMaOEA-RM algorithm can provide a more reliable and efficient migration scheme than existing algorithms.

Study on the adsorption mechanism of fluorescent nano-tracer in sandstone core

Chemical tracer testing technology has increasingly become the preferred method for reservoir monitoring in oil fields due to its low cost and high efficiency. Understanding the migration behavior and adsorption mechanisms of chemical tracers in porous media is crucial for designing tracer injection processes and enhancing the accuracy of tracer test interpretation. This study employs an enhanced Stöber sol-gel method to synthesize fluorescent silica nanoparticles. After surface modification with the silane coupling agent γ-(methacryloyloxy) propyltrimethoxysilane (KH570) and doping with two fluorescent dyes, a multicolor fluorescent nano-tracer (PMFN) was synthesized. This study conducted dynamic and equilibrium adsorption experiments to investigate the adsorption behavior of PMFN on sandstone surfaces. To elucidate the adsorption mechanism of PMFN, we fitted the adsorption equilibrium experimental data using the Langmuir, Freundlich, and Temkin isothermal adsorption models. The adsorption kinetics were studied using the Lagergren, Elovich, and pseudo-first-order kinetic models. Additionally, we assessed the influence of ionic strength and particle size on the adsorption of PMFN by calculating the DLVO interaction forces between PMFN and the sandstone surface. The results showed that PMFN adsorption on sandstone primarily occurs in the pre-contact stage and is characterized by monolayer adsorption. When the ionic strength of the solution is 0.001 mol/L, the maximum repulsive energy barrier between PMFN and the sandstone surface hinders adsorption.

High-priority targets for transient gravitational waves from glitching pulsars

ABSTRACT Glitching pulsars are expected to be important sources of gravitational waves (GWs). In this paper, we explore six different models that propose the emission of transient continuous waves, lasting days to months, coincident with glitches. The maximal GW energy is calculated for each model, which is then used to determine whether associated GWs could be detectable with LIGO-Virgo-KAGRA’s O4 detectors. We provide an analytical approximation to calculate the signal-to-noise ratio (SNR) which includes information about the source’s sky position, improving on previous estimates that assume isotropic or sky and orientation averaged sensitivities. By analysing the entire glitching population, we find that certain models predict detectable signals in O4, whereas others do not. We also rank glitching pulsars by SNR, based on archival data, and we find that for all models, the Vela pulsar (PSR J0835$-$4510) would provide the strongest signal. Moreover, PSR J0537$-$6910 is not expected to yield a detectable signal in O4, but will start becoming relevant for next-generation detectors. Our analysis also extends to the entire pulsar population, regardless of whether they have glitched, and we provide a list of pulsars that would present a significant signal, if they were to glitch. Finally, we apply our analysis to the 2024 April Vela glitch and find that a signal should be detectable under certain models. The non-detection of a supposedly detectable signal would provide an efficiency factor that quantifies a model’s contribution to GW emission, eventually leading to a differentiation of models and independent constraints on physical parameters.

Emergence of information processing in biological systems and the origin of life

ABSTRACT As every life form is composed of cells, elements of consciousness, namely memory and sentience, must be grounded in mechanisms that are integral to unicellular organisms. Earlier studies indicated that cellular cytoskeletal structures consisting of excitable, flexible, and oscillating polymers such as microtubules, along with quantum events, are potentially responsible for information processing and thus consciousness. This work attempts to solve the unknown, that is, how, at the spark of life, the phenomenon of cellular information processing first appears. This study posits that the spatially distributed wave energy of the molecules of an incepting cell interacts with space and generates a rotating bioinformation field, forming a vortex. This vortex, the local energy maximum, whose inbound and outbound energy fluxes represent signal reception and dispersal, is a critical step in the spark of life responsible for information storage, and with incremental wave superpositions, exhibits information processing. The vorticity of the rotating field is computed, and the obtained field characteristics indicated the emergence of a prebiotic complex to initiate information processing. Furthermore, the developed system model explains how perturbations from the environment are converted into response signals for the emanation of sense, locomotion, nutrition, and asexual reproduction, the fundamental evolutionary building blocks of prokaryotes. Further research directions include explaining how the energy potential available in the bio-information field and the vortex leads to the first formation of genetic material, emergence of cytoskeleton, and extension of bio-information field to multi-cellular organisms.

Experimental investigation of inclined solar still through localized interfacial evaporation using nano enhanced Bio wick under disparate flow rate

Water treatment is essential for obtaining potable water, and passive solar desalination offers a renewable and sustainable approach. However, productivity remains a key challenge for commercialization. Scaling up solar desalination systems while maintaining efficiency and cost-effectiveness is a significant challenge. The current state of research in solar desalination is focused on developing scalable and sustainable solutions to address challenges faced in productivity. To address this issue, ongoing efforts focus on improving productivity under localized interfacial evaporation. The present study aims to enhance productivity, particularly at higher mass flow rates, through a series of experiments conducted in three sets. In the first set of experiments, a bare Integrated Solar Still (ISS) was utilized with various mass flow rates (0.29, 0.42, 0.75, and 1.3 kg/min). The highest hourly yield of potable water was observed during peak solar intensity, typically between 13:00 and 14:00 Hrs for all mass flow rates. However, as the mass flow rate increased, the hourly yield of potable water decreased. For instance, at 14:00 Hrs, the maximum yield was 0.235, 0.15, 0.12, and 0.06 kg/m2 for mass flow rates of 0.29, 0.42, 0.75, and 1.3 kg/min, respectively, in the ISS without wick material. The highest cumulative yield achieved was 1.6 kg/m2 during 0.29 kg/min mass flow rate, while the minimum clean water yield of 0.4 kg/m2 was obtained at 1.3 kg/min. In the second set of experiments, the goal was to improve productivity at higher mass flow rates. The use of Fe2O3-impregnated jute cloth in comparison to the bare ISS resulted in an average absorber temperature increase of 4∘C, 4.8∘C, 4.8∘C, and 4.9∘C for mass flow rates of 0.29, 0.42, 0.75, and 1.3 kg/min, respectively. Interestingly, the trend showed an increasing rate of reduction mitigation at higher mass flow rates. Simultaneously, the average water temperature increased by 4.2∘C, 4.5∘C, 6.4∘C, and 7.1∘C for the corresponding mass flow rates with Fe2O3-impregnated jute cloth. The introduction of jute cloth enhanced energy harvesting at all mass flow rates compared to the bare ISS. The maximum energy efficiency, at 48.02 %, was achieved with Fe2O3-impregnated jute cloth during the 0.29 kg/min mass flow rate, while the minimum energy efficiency, at 9.14 %, was recorded at the highest mass flow rate of 1.3 kg/min. Notably, the energy efficiency of the jute cloth-covered ISS surpassed that of the bare ISS by 12.44 %, 9.14 %, 7.15 %, and 3.14 % for mass flow rates of 0.29, 0.42, 0.75, and 1.3 kg/min, respectively. Furthermore, the addition of Fe2O3-impregnated jute cloth further improved energy efficiency, with enhancements of 8.19 %, 1.14 %, 6.36 %, and 9.57 % over the jute cloth-covered ISS for the respective mass flow rates. During the 0.75 kg/min mass flow rate, energy efficiency reached 26.12 %, closely matching the 27.3 % efficiency achieved at 0.29 kg/min in the bare ISS. The study also demonstrated a 2.29 % improvement in exergy with Fe2O3-impregnated jute cloth at a mass flow rate of 0.29 kg/min. In conclusion, the results suggest that the implementation of jute cloth over the ISS absorber basin can enhance overall efficiency and mitigate the negative impacts of increased mass flow rates via localized interfacial evaporation. The combination of a jute cloth wick and Fe2O3 nanoparticles holds promise for improving energy efficiency in solar still desalination.

Computer-Based Experiment for the Motion of Spring Oscillator on a Linear Air Track Using Ultrasonic Sensor.

In the present paper, an affordable innovative physical experimental equipment consisting of an upper computer, an ultrasonic sensor module, and an Arduino microcontroller has been designed. The relationship between the position of the slider fixed on two springs and time is measured by using the ultrasonic sensor module. A system for slider motion data and image acquisition is constructed by using the LabVIEW interface of Arduino UNO R3. The purpose of this experiment is to demonstrate and interpret the propagation of waves represented by harmonic motion. The spring oscillator system including a slider and two springs is measured and recorded, and the motion can be realized using curve fitting to the wave equation in Sigmaplot. The vibration periods obtained from experimental measurements and curve fitting of the wave equation are 1.130 s and 1.165 s, respectively. The experimental data are in good agreement with the theoretical model. The experimental measurement results show that the maximum kinetic energy is 0.0792 J, the maximum potential energy is 0.0795 J, and the total energy at the position of half the amplitude is 0.0791 J. The results verify the mechanical energy conservation of spring oscillator system in a short time. This self-made instrument has improved the visualization and the automation level of the corresponding experiments.

Molecular Docking and Molecular Dynamics Simulations of Synthesized Thiazole-Isatin-1,2,3-triazole Hybrids as Promising Inhibitors for DNA Gyrase and 14α-Sterol Demethylase.

In the present work, a new class of thiazole-isatin-1,2,3-triazole hybrids (5a-5p) and precursor alkyne hybrids (6a-6d) has been reported with their in-silico studies. After structural identifications using different spectroscopic technique such as FTIR, 1H and 13C NMR and HRMS, the synthesized hybrids were explored for their biological potential using molecular docking and molecular dynamics calculations. Molecular docking results revealed that compound 5j showed maximum binding energy i.e. -10.3 and -12.6 kcal/mol against antibacterial and antifungal enzymes; 1KZN (E. coli) and 5TZ1 (C. albicans), respectively.Top of FormBottom of Form Molecular dynamics simulations for the best molecule (100 ns) followed by PBSA calculations suggested a stable complex of 5j with 5TZ1 with binding energy of -118.760 kJ/mol as compared to 1KZN (-94.593 kJ/mol). The mean RMSD values for the 1KZN with 5j complex remained approximately 0.175 nm throughout all the time span of 100 ns in the production stages and is in the acceptable range. Whereas, 5TZ1 with 5j complex, RMSD values exhibited variability within the range of 0.15 to 0.25 nm.

Noise analysis and optical response of microwave kinetic inductance detectors with an optical stack

We report on the experimental investigation of optical coupling for superconducting microresonators known as microwave kinetic inductance detectors (MKIDs) in the visible and near-infrared bands. MKIDs are photon-counting, time and energy-resolving detectors that still suffer from a poor quantum efficiency. To improve this efficiency, we propose to add a superconducting reflective layer below the absorbing part of the detector separated by a transparent Al2O3 layer with a quarter-wavelength thickness optimized around a single wavelength λ = 405 nm. We have first fabricated samples patterned from stoichiometric TiN ( Tc∼4 K), one with the full optical stack, one without for reference and one with a partial optical stack in order to characterize the noise influence of each layer individually. We observe that the full optical stack geometry has the most impact on the resonator’s noise and quality factors. A second design was fabricated to characterize the optical response to short pulses of the optical stack and we show from both the frequential noise and optical response that a strong signature of TLS is still present in the optical stack sample. We have finally obtained single-photon response with the optical stack using a more sensitive tri-layer TiN/Ti/TiN absorber ( Tc∼1.3 K) for which a maximum energy resolving power of R=E/ΔE∼ 1.3 was achieved using 405 nm laser pulses at 225 mK. The quality factors of both the reference and optical stack samples are similar but the frequency noise is still a tenfold higher for the optical stack sample which degrades the energy-resolving power of the detector.

Low‐velocity impact characterization of polyurethane rubber/nano‐clay enriched sustainable sandwich composites: Synergy of experimentation and simulations

AbstractThis research proposes a novel sustainable composite using basalt (B), hemp (H) and polyurethane rubber (Pu) reinforced in nano clay functionalised epoxy matrix for sacrificial structural applications prone to low‐velocity impact (LVI). To this end, symmetric and asymmetric laminates such as HHHH, BBBB, BHHB, BHPuHB, BBPuHH and BPuBPuHPuH are fabricated using compression molding techniques and subjected to LVI at three different impact energies of 19.66, 39.39, and 59.05 J. The hemp fibers were treated with NaOH solution before fabrication. Material characterization such as X‐ray diffraction, Raman spectroscopy and morphological studies has been carried out. The impact and post‐impact properties of the proposed composites are experimentally evaluated and validated with the finite element (FE) results. The effect on the residual tensile strength degradation of laminates at different interlayers and energy levels is also investigated using the Caprino analytical model. The barely visible impact damages (BVID) are investigated through non‐destructive dye‐penetration tests, which facilitate easy identification of the prominent LVI damages like “Plateau” and “Cliff‐drop” impressions. Based on the impact energy absorption and residual tensile strength, proposed laminates followed BHPuHB > BBBB > BHHB > HHHH. The experimentation suggests that Polyurethane core laminates support maximum impact energy absorption by favoring a structural change in interlayers. Also, the residual tensile strength decreases as impact velocity increases.Highlights Low‐velocity impact behavior of sustainable composites is experimented. Basalt, hemp and polyurethane rubber are reinforced in nano clay epoxy matrix. A FE framework to validate the experimentation is proposed. Dye penetrant NDT is adopted to investigate the damages. Morphological studies are conducted to understand LVI responses.

Low-voltage ride-through strategy for an integrated permanent magnet synchronous generator in a flexible interconnected distribution network

For the permanent magnet synchronous generator (PMSG) integrated into the flexible interconnected distribution network (FIDN), its low-voltage ride-through (LVRT) strategy needs to be designed to enhance the transient operation capability of the FIDN. The design of the LVRT strategy also needs to take the fault location of the FIDN into consideration. To deal with faults occurring on the integrated feeder of the PMSG, the PMSG needs to realize successful LVRT using the hardware protection equipment. To deal with faults occurring on the feeder adjacent to the integrated feeder of the PMSG, the PMSG needs to release its stored energy to temporarily increase its active power output, which is then supplied to the loads on the faulted feeder that are isolated from the fault through the soft open point (SOP). In this paper, a novel LVRT strategy designed for the PMSG integrated into the FIDN is proposed, which includes dual operation modes that are separately applied to different fault locations. If PMSG is on the faulted feeder, the DC-link voltage of the PMSG is maintained with the controllable resistive fault current limiter (CRFCL), while the maximized stored kinetic energy is reserved to enhance the generation efficiency during the LVRT. If PMSG is on the feeder adjacent to the faulted feeder, the control strategy of the converters of the PMSG is adjusted in response to the power regulation goal at the SOP. Meanwhile, the maximum releasable kinetic energy of the PMSG is considered when increasing its active power output. The feasibility and effectiveness of the LVRT strategy for the PMSG are verified based on the numerical analysis.

Analysis of Energy Potential of Switchgrass Biomass

In this research, the energy potential of switchgrass (SG) was analyzed to find promising directions for producing bioenergy from this biomass. The first direction is determining the thermal energy of bioethanol extracted from SG biomass after its pretreatment, enzymatic hydrolysis (saccharification), and fermentation of the resulting glucose. It was established that after a two-stage pretreatment of 1 ton of SG with dilute solutions of nitric acid and alkali, the largest amount of bioethanol can be extracted with an energy potential of 4.9 GJ. It is also shown that by the utilization of solid and liquid waste, the production cost of bioethanol can be reduced. On the other hand, the direct combustion of 1 ton of the initial SG biomass used as a solid biofuel provides an increased amount of thermal energy of 18.3 GJ, which is 3.7 times higher than the energy potential of the resulting bioethanol extracted from 1 ton of this biomass. Thus, if the ultimate goal is to obtain the maximum energy amount, then another direction for obtaining bioenergy from biomass should be implemented, namely, direct combustion, preferably after pelletizing. Studies have shown that fuel characteristics of SG pellets such as the gross thermal energy and density of thermal energy are lower than those of wood pellets, but they can be improved if the SG biomass is densified into pellets together with binders made from polymer waste.

Nonlinear spatial evolution of degenerate quartets of water waves

In this manuscript we investigate the Benjamin–Feir (or modulation) instability for the spatial evolution of water waves from the perspective of the discrete, spatial Zakharov equation, which captures cubically nonlinear and resonant wave interactions in deep water without restrictions on spectral bandwidth. Spatial evolution, with measurements at discrete locations, is pertinent for laboratory hydrodynamic experiments, such as in wave flumes, which rely on time-series measurements at fixed gauges installed along the facility. This setting is likewise appropriate for experiments in electromagnetic and plasma waves. Through a reformulation of the problem for a degenerate quartet, we bring to bear techniques of phase-plane analysis which elucidate the full dynamics without recourse to linear stability analysis. In particular we find hitherto unexplored breather solutions and discuss the optimal transfer of energy from carrier to sidebands. We show that the maximal energy transfer consistently occurs for smaller side-band separation than the fastest linear growth rate. Finally, we discuss the observability of such discrete solutions in light of numerical simulations.

Coercivity of (Fe0.7Co0.3)2B Nanowire and Its Bonded Magnet

(Fe0.7Co0.3)2B are potential permanent magnets material due to its large saturation magnetization and high Curie temperature. However, it has moderate magnetocrystalline anisotropy (MCA) and low coercivity. One way to improve its coercivity is to combine the contributions from magnetocrystalline- and magnetic-shape anisotropy by preparing (Fe0.7Co0.3)2B nanowires. We study the effects of size, morphology, and surface defects on the hard magnetic properties of nanowires using micromagnetic simulation. The hard magnetic properties of (Fe0.7Co0.3)2B nanowire-bonded magnets are estimated, including the role of inter-wire magnetostatic interaction. By considering the existence of local reductions in MCA energy of up to 30% on the surface layer of nanowires, the anisotropic bonded magnet with a 65% vol. of (Fe0.7Co0.3)2B nanowires would have typical remanence, Br= 7.6–8.4 kG, coercivity, Hci= 9.6–9.9 kOe, and maximum energy product, (BH)m = 14–17.8 MGOe. Developing effective technology for synthesizing nanowires and fabricating corresponding bonded magnets is promising for manufacturing practical magnets based on the magnetic phase with a relatively low or moderate MCA, such as (Fe0.7Co0.3)2B.

The enhancement and impact of Se doping on the electrochemical properties of LiMn2O4 cathode material for aqueous Li-ion batteries

Spinel LiMn2O4 is a promising cathode material for lithium-ion batteries. However, due to the Jahn-Teller effect and Mn dissolution, its capacity decreases seriously in the cycle process, which hinders its wider application. In the course of our research, we discovered that a modest infusion of Se-doping is capable of significantly augmenting the oxygen vacancy within the material, improve the conductivity of the LiMn2O4 material and promotes superior battery performance. Moreover, due to Se-doped the average valence state of Mn is raised, which effectively mitigates the Jahn-Teller effect. The optimized sample exhibits high capacity, long cycle life, and superior rate capability, with an initial discharge specific capacity of 101.0 mAh·g−1 at 7 C and capacity retention of 87.3 % after 200 cycles. The maximum specific discharge capacity of the full battery during the cycle was 97.9 mAh·g−1, the capacity retention rate after 200 cycles was 78.2 %, and the maximum energy density during the cycle is 145.1 Wh·Kg−1, which was nearly twice that of the single lithium-ion battery in this paper. The effect of Se-doped on the properties of LiMn2O4 cathode materials provides a new idea for the development of high-performance spinel lithium manganese oxide cathode materials.

Improving building energy efficiency through ventilated hollow core slab systems

The increasing desire for comfort and healthy indoor environment, as well as improvements in energy standards in recent years, have stressed the need to make an active use of the building mass to achieve the maximum energy saving This is why the application of ventilated hollow-core slab systems (VHCS) can be considered as one of the innovative approaches. These systems have precast concrete slabs with tubular voids directing ventilation air on its length. In the present study Solving this system numerically using the ANSYS fluent program to study the temperature distribution and air flow in the 3-D test model of the present study to determine the feasibility of applying this system in an arid climate especially in Iraq by checking the inlet velocity and temperature and to predict the impact of these operating parameters on human comfort and energy savings. The study aimed to provide a numerical analysis of a conditioned zone's temperature distribution using VHCS. The investigation was carried out on a scale model room of size (1 m × 1.2 m × 1 m) with a scale factor of ¼. Four distinct scenarios were examined: the first two cases occurred during a no-load time in the night when there were no internal or external loads and examined the effects of changes in inlet temperatures and air velocities. The remaining two scenarios were conducted during an occupied period with internal heat gain of 630 W/m2 and external heat gain of 800 W/m2 based on the SHGC for the summer season of Iraq. As previously demonstrated, setting the inlet velocity to 1 m/s resulted in an optimal temperature and velocity distribution in the main flow, irrespective of changes in the external and internal loads and temperatures of the supply core. The findings shown that input air velocity and temperature affect heat remove efficiency. In addition, numerical outcomes have also illustrated that the Thermal Active VHCS System, while used in combination with ventilation strategies, could indeed regulate the space conditions by cooling down the building's ceiling, thus eradicating stored heat. All investigations found VHCS systems suitable for air conditioning in dry and hot locations. The systems are known for their ease of use, simplicity, high performance, comfort, and energy savings. They can also reduce peak loads to boost structural energy efficiency.

Excellent electrochemical performance of N and Mn doped NiCo2O4 functional nanostructures: an effective approach for symmetric supercapacitor application

In supercapacitors (SCs), cobaltite spinel is considered as an excellent electrode material because it is abundant on earth, cost-effective, and theoretically capable of achieving high capacitance values. However, there are number of factors that prevent spinel cobaltite from achieving its maximum theoretical specific capacitance, including low electrical conductivity, insufficient active sites, and slow charge transport. For these reasons, it is necessary to simplify the structural and compositional design to overcome these limitations. An efficient solvothermal method followed by pyrolysis was successfully used to shape NiCo2O4 nanoflowers doped with N (Nitrogen) and Mn (Manganese). In addition to increasing the ion diffusion resistance and charge transfer resistance, N and Mn-doped NiCo2O4 provides an electrical conductivity system. The optimized N, Co, and Mn4 (NCoMn4) nanoflowers (4 wt% Mn-doped NiCo2O4) exhibits maximum specific capacitance of 269Fg−1 at 1Ag−1 current density with an exceptional retention of capacitance 92% after 5,000 uninterrupted cycles in the Na2SO4 media. The electrokinetic analysis of NCoMn4 further indicates that overall charge is stored predominantly through capacitance, as compared with other electrodes. It is also worth noting that the as-fabricated symmetric supercapacitor delivers the maximum energy density of 36.11 Whkg−1 at a power density of 1.04 kWkg−1 at 1 Ag−1 current density. This work opens a new path to develop hybrid electrodes for enhanced supercapacitor applications and will specify an efficient method for improving the charge transfer capability.

The possibility of using the DKS-AT1123 dosimeter for radiation monitoring of medical electron accelerators with the energy of more than 10 MeV

In the Russian Federation, there is a constant increase in the number of radiation medical installations with electron accelerators. Over the past 4 years, their number has increased 2.5 times. These installations contain pulsed electron accelerators that generate pulsed bremsstrahlung radiation with a maximum energy from 6 to 21 MeV. Currently, there are no devices designed for dosimetry of the pulsed photon radiation with energy of more than 10 MeV in the state register of measuring instruments of the Russian Federation. The most widely used radiation monitoring device for pulsed electron accelerators is the DKS-AT1123 X-ray and gamma radiation dosimeter designed for dosimetry of pulsed bremsstrahlung radiation with an energy of up to 10 MeV. The purpose of this work is to evaluate the possibility of using this device for dosimetry of pulsed bremsstrahlung radiation with a maximum energy of up to 20 MeV. The authors calculated the energy spectra of bremsstrahlung radiation for a point source with a maximum energy of 20 MeV behind flat concrete screens with a thickness of 1 m, 2 m and 3 m by the Monte Carlo method using the GEANT4 calculation program. The energy dependence of the registration efficiency of the DKS-AT1123 dosimeter was extrapolated to the energy range of 10–50 MeV in the kerma-approximation without taking into account the energy transfer by secondary electrons. It was assumed that it corresponds to the energy dependence of the total mass attenuation coefficient for the absorbed energy of gamma quanta in water. Using conversion coefficients for converting the fluence of monoenergetic photons into the effective dose rate at an anterior-posterior radiation incidence on the human body, real dose rates were calculated, and using the energy dependence of the dosimeter readings, the predicted results of measuring the unit dose rate with the DKS-AT1123 dosimeter behind a concrete protection with a thickness of 1, 2 and 3 m were obtained. It is shown that the maximum expected underestimation of the measurement results will not exceed 40% and practically does not depend on the thickness of the concrete shield in the thickness range from 1 to 3 m. To account for this underestimation, it is necessary to use the value of additional measurement error due to the energy dependence of the sensitivity of this device for the photon radiation energy of more than 10 MeV, equal to 70%. This makes it possible to use the measurement results obtained using this dosimeter to adequately characterize the state of radiation safety during operation of pulsed electron accelerators with a maximum energy of up to 20 MeV. It is possible to use a correction factor to the measurement results equal to 1.63 ±0.04 to compensate for this underestimation. The proposed approach can be used to create a methodology for using this dosimeter for radiation monitoring of medical electron accelerators with the energy of up to 20 MeV, if there are correction factors for radiation protection configurations and radiation energies encountered in practice.

Probabilistic fatigue life prediction of notched specimens based on modified stress field intensity method under multiaxial loading

In practical engineering components, due to the existence of non-uniform stress and strain field near the notch, it brings severe challenges to fatigue life prediction when evaluating the integrity of notched components. In this study, a probabilistic fatigue life prediction model for notched specimens was established by coupling the stress field intensity (SFI) method and Weibull distribution. Firstly, the position of the dangerous point is determined by finite element calculation, and the maximum strain energy density plane through the dangerous point is defined as the critical plane. Secondly, from the perspective of 2D features, the traditional SFI method is modified based on the stress distribution on the critical plane, and a new concept of effective stress is proposed to predict the fatigue life of notched specimens by the experimental data of smooth specimens. Finally, a new non-proportional additional hardening factor is established to characterize the influence of material properties and loading path on fatigue life. The experimental data of Q345 low alloy steel and GH4169 nickel base alloy are used to compare and analyze the proposed model. The results show that the predicted life of the proposed model is in good agreement with the experimental life.