Maximum Increment Research Articles

Multi-wall carbon nanotubes tailored eutectic composites for solar energy harvesting

Carbonaceous thermal energy storage involving PCMs has gained an increasing research interest owing to their higher thermal conductivity and energy storage density. The current work analyses the thermophysical properties of a nano-enhanced eutectic phase change material (NeUPCM) laden with different concentrations (ranges from 0 wt% - 0.7 wt%) of multi-wall carbon nanotube (MWCNT). Paraffin wax-palmitic acid (PW-PA) binary eutectic was produced initially by facile melt blending, and then MWCNTs were doped via standard two-step nanocomposite synthesis protocol. Nanocomposites showed a slower decomposition rate, and the thermal resistance index improved. MWCNT enhance the thermal conductivity of the eutectic base (140 %), which reaches a maximum value of 0.619 W/(m·K) for 0.5 wt% loadings, and the maximum increment of 13.2 % of latent heat was noted for 0.7 wt% loading of MWCNT (which is having a melting temperature of 53 °C). The sample doped with 0.5 wt% MWCNT(C3) showed the highest thermal effusivity. The NeUPCMs also displayed improved photothermal performance and solar absorptivity. Corrosion analysis against copper revealed that the composite is suitable for long-term usage. The NeUPCMs maintained good reliability even after 500 melt-freeze cycles. In short, the proposed NeUPCMs hold significant potential to be employed for thermal energy storage purposes.

Analysis of solar water desalination using hybrid nanofluids: An experimental study

The performance characteristics of a novel solar water desalination system has been inves-tigated experimentally. The desalination unit consisted of a square basin-pyramid solar still coupled with a solar heater. Different DI water based mono and hybrid nanofluids were pre-pared using CuO and GO nanoparticles following the two-step method. DI water when em-ployed as the heat transfer fluid in the system, improved the distillate water yield by about 28.80% relative to the conventional solar still. Out of all the considered CuO mono-nano-fluids, the 1.0 wt.% concentration resulted in the maximum increment of about 78.80% in the distillate water yield followed by 1.5 wt.% (62.05%) and 0.5 wt.% (53.30%) respectively. Utilizing the CuO+GO hybrid nanofluid, resulted in maximum increment of about 127.46% at 25:75 nanoparticle proportion followed by, 50:50 (101.33%) and 75:25 (89.30%) respectively, while employing the 1.0 wt.% GO mono-nanofluid, resulted in an increment of about 54.93% in the distillate water yield. The pumping power of the prepared nanofluids was found to be the function of their concentration. Hence, the performance index was evaluated for all the tested heat transfer fluids followed by an economic analysis of all the considered cases. The pu-rity of the produced distilled water was also assessed by comparing with the Bureau of Indian Standards. Finally, the study proposed the best suitable heat transfer fluid for the investigated system and suggested the possible futuristic research objectives.

English

Potential of auxin and ACC-deaminase producing rhizobia and PGPR-strains was examined to improve soybean growth individually and in combination with L-tryptophan (L-TRP) in two different experiments conducted in a growth chamber. A consortium of selected PGPR and rhizobial strains was prepared by following the compatibility test. These bacteria were also evaluated for improving soybean growth along with different levels of L-TRP. Bacteria were isolated from the rhizosphere and nodules of soybean, and characterized in vitro for their production of ACC-deaminase and auxin. We observed that auxin production for rhizobia and rhizobacteria ranged from 14 to 39 and 2 to 48 µg IAA equivalents mL-1, respectively. Similarly, the ACC-deaminase production potential of rhizobia and rhizobacteria ranged between 0.024 to 3.252 and 0.178 to 3.188 μM α-ketobutyrate μg-1 protein h-1, respectively. In addition, among the different L-TRP levels, 10-3 M was found to be the most significant level. The soybean growth attributes such as shoot length (46 and 30%), root length (42 and 39%), fresh biomass (33 and 34%) and dry biomass (44 and 27%) were increase to the maximum by the inoculation of ‘IRS-13’ and ‘PS-2’ in the presence of 10-3 M L-TRP compared to the uninoculated control. Similarly, in the context of consortium application, the inoculation with bacterial consortium “IRS13-PS1” along with 10-4 M TRP led to maximum increment in shoot length (104%), root length (74%), shoot fresh and dry weights (179 and 138%), shoot and root dry weights (98 and 260%) and fresh weight as well as dry plant biomass (87.5 and 117%) compared to the control. We concluded that PGPR-rhizobial consortium in combination with L-TRP @ 10-4 M can effectively improve soybean growth under axenic conditions.

Fabrication and structural, physical, and nuclear radiation shielding properties for Oxide Dispersion-Strengthened (ODS) alloys through Erbium (III) oxide, Samarium (III) oxide, and Praseodymium (III) oxide into 316L matrix

We report a comprehensive investigation on customization process of Oxide Dispersion-Strengthened alloys through Sm2O3, Pr2O3, and Er2O3 incorporation into 316L stainless steel matrix in terms of a desired enhancement in structural, physical, and nuclear radiation shielding properties. Oxide powders are incorporated into 316L stainless steel powder all with the same purity of 99.5%. These were Erbium oxide (Er2O3), Praseodymium oxide (Pr2O3), and Samarium oxide (Sm2O3). First, X-Ray diffraction and Scanning Electron Microscope/Energy-dispersive X-ray spectroscopy analyses are conducted in order to investigate their physical and structural properties. Next, two different experimental setups are employed using a133Ba and 241Am/Be sources for the measurements of gamma-ray and neutron transmission properties of Oxide Dispersion-Strengthened alloys. The maximum density increment is achieved through Er2O3 compared to other reinforced oxides. The detector counting value reached its minimum level when a 5% Er2O3 oxide dispersion was introduced into the 316L SS matrix. Similarly, the most significant degree of photon absorption, the highest values of mass attenuation coefficient, lowest half value layer, and most effective atomic number, were all attained by the same sample. Based on the findings derived from the investigation, it can be concluded that incorporating Er2O3 oxide into 316L steel can be considered as a viable option in terms of enhancing the critical properties of Oxide Dispersion-Strengthened alloys for extreme conditions such as nuclear reactors and other similar fields, where the behavioral attributes of the utilized materials are at utmost importance.

Modeling market trading strategies of the intermediary entity for microgrids: A reinforcement learning-based approach

Participation of a large number of microgrids (MGs) in the energy markets faces several challenges. To address these challenges, MGs can be aggregated by an Intermediary entity (IE). In this paper, a new decision-making framework is proposed to solve the energy management problem of multiple MGs and their participation in the energy market through the IE. This framework has three main functions. First, energy price forecasting is conducted using the long short-term memory (LSTM) recurrent neural networks method. Then, the power exchange of the MGs with the main grid is optimized by solving their energy management problem. In this stage, the integrated power exchanges of the MGs with the grid are determined based on the predicted prices. In the final function, the Monte Carlo reinforcement learning technique is employed to optimize real-time pricing decisions and identify potential obstacles that may affect proposed bid prices. This approach addresses energy management challenges and enables profitable energy trading in multiple MGs within energy markets, with confirmation supported by simulation results. The results show a maximum increment of 4.55% in the profit of the IE when purchasing energy and a 3.79% maximum increment when selling energy in the real-time market compared to day-ahead decisions, respectively.

Effect of flame thickness on the temperature measurement error for bare-bead thermocouple in open pool fires with different fuels

Accurately obtaining the temperature distribution of the flame is crucial for a comprehensive understanding of the combustion behavior of the pool fire. The correction method is needed to compensate the measurement error when the temperature is measured by bare-bead thermocouple in the open pool experiment, but the effect of flame thickness is rarely considered in the current method. Thus, this work develops a coupled heat transfer model of bare-bead thermocouples in open pool fires and modifies the flame radiation characteristics based on the fuel type and flame thickness. The control mechanism of measurement error in the model is identified, and then the effects of main parameters such as flame thickness and flame temperature on measurement error are analyzed. The results show that the flame emissivity decreases exponentially with the decrease of flame thickness, the minimum emissivity of gasoline flame is 0.26 when flame thickness is 0.1 m. The decrease of flame thickness leads to a sharp increase of temperature measurement error. The maximum increment of error can reach 227.3 K. On this basis, the flame thickness limit value, considering the correction of temperature measurement error in different hydrocarbon pool fire experiments is proposed.

Experimental exploration of hydrogen fuelled dual fuelled CRDI equipped diesel engine coupled with exhaust gas recirculation using ANN approach

The usage of diesel engines in the automobile and agricultural industries is growing daily. Therefore, this study aims to reduce the rate of exhaust emissions from water-cooled 4-stroke-single cylinder CRDI-equipped diesel engines by using hydrogen along with the exhaust gas recirculation (EGR) technique. The results proved that the dual-fuelled diesel engine enriched with 6 ms of hydrogen flow rate and 10% EGR promotes excellent engine characteristics. However, the reduced NOX emission was observed from 10% EGR application. Compared to pure diesel, the proposed dual fuel combination promotes 56.3%, 33%, 15.38%, 40% and almost 50% reduction in HC, CO, NOX, CO2 and smoke emissions. Similarly, the engine performances, such as brake thermal efficiency (BTE) and brake specific energy consumption (BSEC), have also been improvised. The maximum increment achieved for BTE is 7.6%, and the maximum reduction achieved for BSEC is 8.12%. Besides, the ANN model predicts the engine performance and emissions with a correlation coefficient of 0.964, 0.945, 0.98, 0.807, 0.979, 0.900, and 0.90 for BTE, BSEC, CO, CO2, NOX, HC and smoke respectively. A root mean square error (RMSE) of less than 1 was observed for the ANN prediction model, indicating that both the actual and predicted results agree better.

Ferromagnetic Resonance Heating of Magnetic Nanoparticles Resovist for Biomedical Applications

Ferromagnetic resonance (FMR)-based magnetic energy dissipation potentially generates effective heating for cancer therapy in magnetic hyperthermia. We demonstrated the FMR characteristics of normal/customized Resovist® (particle sizes of 60 and 16 nm) for biomedical applications and revealed the bias magnetic field-dependent FMR spectrum in the range of 1–10 GHz under 0–2000 Oe. Moreover, an improvement in heating power was observed under the FMR condition. The maximum temperature increment rate was 2.5 °C/s, which is 10-fold greater than that of conventional magnetic hyperthermia with a frequency range of several hundred kHz. Our results indicate that magnetic hyperthermia by utilizing FMR enables the progressive study of cancer treatment.

Numerical investigation of model Francis turbine for performance enhancement with geometrical modification

Most of the hydropower plants in Nepal are run-of-river type and over 60% of them are operating with Francis turbines. There are huge fluctuations in flow during the dry and wet seasons, which force the power plant owner to operate the turbines at off-design conditions which can induce cavitation and fatigue loads on the turbines. This study focuses on numerical analysis of a model turbine designed for the Jhimruk hydropower plant in Nepal. A geometrical modification is made to the model turbine runner blades by attaching two pairs of vortex generators (VGs) to each blade surface on the pressure side at 0.5% span, at the leading edge. The flow on the blade breaks off and separates from the surface during the off-design conditions so VGs are introduced to mitigate swirls generated at the inlet of the turbine. VGs can help to reattach the flow and improve off-design performance of the turbine. The performance of model turbine is analyzed at different guide vane openings to simulate different operating conditions by keeping the operating head constant and varying the rotational speed of the turbine from 500 to 1500 rpm. Performance curves and hill diagrams of the turbine are generated for each case with and without VGs. The results show that VGs at off-design conditions show a maximum increment in efficiency by 12% and 1 to 5% on average. The power output is also boosted by 1 to 6 kW at off-design conditions. This objective has been achieved when compared to efficiency and power at low-discharge and high-speed regions. In conclusion, VGs are simple but effective tools to enhance the performance of hydraulic turbines as well.

Treatment measures for the creep–slip phase of landslides induced by twin tunnels

Tunnel excavation in geologically challenging areas can lead to slope instability and consequent landslides, which pose a serious threat to the integrity of the tunnel lining. To address this issue, a study was conducted to investigate the stability of the tunnel–landslide system using the finite-difference method (FDM) based on the Hanshankou tunnel of the Shaoguan–Xinfeng expressway in Guangdong province, China. A plane-strain model was used to examine the effect of various treatment measures on the system, and the strength reduction (incremental) method was employed to determine the range of initial slope safety factors applicable to different treatment measures, with the maximum shear strain increment serving as the criterion. The ‘anti-slip pile + anchor frame beam’ reinforcement system was found to be the most effective solution, reducing daily deformation by 60.1% after implementation. The results indicated that the pile–anchor reinforcement system can significantly mitigate landslide creep, and the corresponding treatment measures can be categorised based on the critical slope safety factor under different conditions.

Investigation of heat transfer augmentation and friction factor in twisted tape-based earth-to-air-heat exchanger: a CFD-based analysis

Earth air heat exchangers (EAHES) are an innovative way to heat and cool buildings by utilising the earth’s natural temperature. Utilizing twisted tape (TT) as an enhancement technique in the EAHE can significantly boost heat transfer passively. This study employs CFD simulations (Ansys Fluent 2022) with SST turbulence model for a fixed Reynolds number range (20,000–52,000). The Twist Ratio (y/w), representing the number of turns of TT inserts, is a critical roughness parameter. The ground temperature across whole soil domain is held constant at 26.7°C. Numerical results are validated against available data showing a close match, particularly at the outlet temperature. Maximum decrement in temperature at exit of EAHE for smaller twist ratio(y/w) is 19.53% as compare from conventional (plain pipe) EAHE for cooling mode. Nusselt number increment of the current design is 50.41% more than the previous design with TT inserts of Re = 51344, number of turns(y/w) = 15, respectively and for friction factor the maximum increment is 2.253 times without TT inserts EAHE at Re = 20573 for 15 turns, respectively. The maximum thermal performance factor improves by 1.19 times with TT inserts in EAHE, achieved at 15 turns and a Reynolds number of 51,344. Abbreviations: EAHE: earth to air heat exchanger; TT: twisted tape; LES: Large Eddy Simulation; RANS: Reynolds-Averaged Navier-Stokes.

Distribution and dynamics of antibiotic resistance genes in sludge under discharge plasma oxidation

Antibiotic resistance genes (ARGs), emerging environmental contaminants, have been largely accumulated in sludge during wastewater treatment. Discharge plasma oxidation, an advanced oxidation technology, has been demonstrated as an effective strategy in sludge pretreatment. However, the effect of plasma oxidation on the distribution and dynamics of ARGs in sludge is unknown. Herein, the variations of four typical ARGs (tetC, tetW, blaTEM-1, aac(3)-Ⅱ) and one integron (intI-1) in sludge during discharge plasma treatment were investigated. The results showed that under low discharge voltage or short treatment time, weak plasma oxidation enriched the contents of ARGs and intI-1 in sludge (with 1.14 log unit maximum increment) via proliferating biomass or promoting horizontal gene transfer. Further increasing discharge voltage or prolonging treatment time, strong plasma oxidation eliminated target genes due to the destroyed bacteria or inhibited horizontal transfer of ARGs. Especially, the homogeneous condition greatly promoted the reduction of ARGs in liquid phase (up to 1.52 log unit reduction). Furthermore, the correlation analysis between intI-1 and ARGs implied that tetC and tetW abundances might be significantly affected by intI-1 through horizontal transfer. At the same time, the microbial communities in sludge were investigated to help understand the effect of plasma oxidation on ARGs variation. Notably, the most predominant phylum Proteobacteria and genus Acinetobacter resisted the oxidative infringement from plasma to maintain high relative abundances (52.05 % in solid phase and 84.10 % in liquid phase for Proteobacteria, 13.82 % in solid phase and 78.00 % in liquid phase for Acinetobacter at 20 kV). Meanwhile, the co-occurrence analysis between genes and dominant genera further showed that Romboutsia sp. might be a potential host bacteria of ARGs and intI-1 in solid phase, and Acidovorax sp., Parachlamydia sp., and Armatimonadetes_gp5 sp. might be the potential hosts of tetW, tetC, and intI-1 in liquid phase.

Effects of particle size and storage length on the fermentation pattern and ruminal disappearance of rehydrated corn grain silage hammer mill processed

The aim of this study is to determine whether the particle size interacts with the storage length to affect the fermentation pattern and the ruminal disappearance of rehydrated corn grain silage (RCGS). It was also assessed whether particle size affects the minimum storage time in relation to the disappearance of ruminal dry matter (DMD). The treatments consisted of six mean particle sizes of RCGS ground in a hammer mill, resulting from different grinding degrees (0.97 mm, 1.11 mm, 1.35 mm, 1.51 mm, 1.69 mm, and 1.75 mm), which were stored for 15, 30, 60, 120, and 240 days. Data were analyzed as repeated measures using the MIXED procedure. When effects of interaction between factors were identified, data were analyzed as polynomial contrasts. Ruminal in situ DM disappearance was modeled across different storage lengths using a non-linear regression model. Prolamin was higher in 1.69 mm and 1.51 mm silages at 15 and 30 days of storage (P < 0.05). Also was observed a decrease in prolamin at 240 days of storage (P < 0.01). The pH of silages was lower after 60 days of storage (P < 0.01), a reduction which is linked to the smaller particle size in 1.11 mm and 1.75 mm silages (P < 0.01). No interaction effects were identified between storage length and DM loss. A greater loss occurred in 1.69 and 1.75 mm silages at 15, 30, and 240 days. At 15 and 60 days, a quadratic behavior was observed, varying according to the increase in particle size. Acetic acid, ethyl lactate, and 1,2 propanediol concentrations increased with storage length (P < 0.01). Lactic acid concentration was affected at 240 days, exhibiting a quadratic behavior according to particle size. The growth pattern of LAB exhibited a quadratic behavior as the mean RCGS particle size increased. The aerobic stability of silages increased after 60 days of storage (P < 0.01), and an interaction effect was found in relation to particle size. According to the Broken-line linear-linear model, maximum disappearance increments were observed at 36, 38, 39, 50, 54, and 46 days of storage for silages with particles measuring 0.97 mm, 1.11 mm, 1.35 mm, 1.51 mm, 1.69 mm, and 1.75 mm, respectively. All silages exhibited an adequate fermentation, and the minimum storage length depended on the particle size of RCGS ground in a hammer mill.

Effect of tri-ethylene glycol mono methyl ether and alumina additives on ignition delay in a hydrogen fuelled dual-fuel diesel engine

The diesel engine process including fuel injection, fuel spray, air and fuel mixing, ignition and combustion which influences its performance and emission characteristics. The fuel injection and fuel spray are important process as they are directly related to the quality of fuel which results into fluctuating the ignition and combustion characteristics. Ignition in a diesel engine occurs at the edge of the spray depending on the in-cylinder pressure and temperature. Experiments were conducted on a modified dual-fuel diesel engine (3.5 kW power) with fuel additives, diesel and hydrogen (gaseous fuel) at a stable speed of 1500 rpm. Spray behavior and ignition delay were analyzed to determine the impact of fuel additives in neat diesel combined with hydrogen. Additionally, for dual-fuel Cases, the ignition delay correlations provided for diesel engines have been modified as per the experimental results. The injection velocity was maximized with a 15–25% hydrogen substitution range because the fuel density was reduced to a minimum, but it was decreased with the addition of fuel additives. The SMD for hydrogen with neat diesel and diesel with fuel additives both increased up to 20% hydrogen substitution, whereas for higher hydrogen substitution, the Sauter mean diameter decreased. It was found that the addition of fuel additives in diesel resulted into an increased fuel injection velocity (3.3%) with reduced sauter mean diameter of 3.4% while with the lower substitution of H2 (15%), a maximum increment of 32% in the injection velocity was seen as compared with neat diesel operation. With 15% hydrogen substitution, the change in pressure and density of diesel along with fuel additives accommodated the optimum spray penetration equivalent to neat diesel. In all Cases of hydrogen substitution, the experimental and theoretical values obtained for the chemical ignition delay were found to be consistent with one another except for 35% H2 showing a maximum deviation of 0.2%.

Enhancement of heat transfer by flowing turbulent jet on a linearly decaying (LD) wavy wall

The influence of a partial linearly decaying (LD) wavy wall on different fluid flow and thermal parameters has been investigated for the turbulent jet. For the present study, a segment of wall from the leading edge is made with a constant amplitude 0.8a (a = nozzle height), followed by a segment of LD wavy wall. In the region of LD wavy wall, the amp (amplitude) of wavy wall is linearly reduced from 0.8a amplitude to 0a in the downstream direction. The LD wavy wall segment varies from 100% to 0%. For 100% LD wavy wall, the whole wall is made of linearly decaying amplitude, whereas for, 0% LD wavy wall, the whole wall is made wavy with a constant amplitude. The Reynolds number at the inlet is same for all the cases, i.e. 15,000 to maintain the fully turbulent condition at the exit of nozzle. The problem is solved numerically using k−ε RNG model. The results obtained from this study show that for 100% LD wavy wall the velocity decay is minimum and as the % of LD wavy wall decreases, the velocity decay increases. Whereas the thermal decay of jet is maximum in the case of 100% LD wavy wall. Similarly, Ymax, YTmax, and the velocity and thermal jet spread are found to be minimum for the 100% LD wavy wall and all these parameters increase as the % of LD wavy wall decreases. The maximum increment in the heat transfer rate is 27.9% for 100% LD wavy wall in regards to the baseline case (plane wall). However, the maximum increment in thermal hydraulic performance (THP) is noticed for the wavy wall with 50% LD wavy wall, which is equal to 6.7%. In a previous study (ArchanaKumari, 2021 [1]), the increment of 19.0% and 5.3% is observed for the heat transfer and THP respectively. In the present study by introducing LD wavy wall, the increment in the heat transfer and THP are quite significant.

Optimization of a novel drive mechanism approaching the ideal cycle for beta type Stirling engines

Stirling engines are capable in the renewable energy gain and the recovery of waste heat, both of which are important issues today. Existing studies revealed that the piston trajectories convergent to the Stirling cycle provide more power than traditional crank mechanism. In this study, a hypocycloid drive mechanism not used in the literature was optimized on the ideal piston trajectories for beta type Stirling engines. Optimization was realized to improve the isochoric heating and cooling processes as well as the isothermal compression and expansion. The cyclic work was treated as another objective succession. The optimal results taking into account these five objectives were obtained with the gear ratios of 5 and 4 for displacer piston and power piston, respectively. The piston dwells provided the enough objective succession not only for the both isochoric processes but also for the isothermal compression process, while failed in the isothermal expansion. In comparison with crank mechanism, a cyclic work increment of 10% was achieved in the near-ideal piston trajectories, but the maximum increment of 14% eventuated in some out of ideal.

Frequency control using electric vehicles with adaptive latency compensation and variable speed wind turbines using modified virtual inertia controller

In this paper, to reduce the effect of low inertia consequences, electric vehicle (EV) and variable speed wind turbine (VSWT) are adopted to collaborate in the power system frequency regulation. A virtual inertia controller based on the IEC 61851 standard is proposed to benefit from EV contribution in frequency regulation. In this controller, the rate-of-change-of-frequency (ROCOF) is measured and an appropriate EV current set point is obtained. Furthermore, to decrease the effect of frequency regulation on EVs owners, a stochastic allocation method of the regulation sequence among EVs parking lots is presented. One of the barriers of employing EV in the frequency regulation is the communication latency. To overcome this issue, according to the measured latency, a weighted combination of several compensators which is called adaptive latency compensator (ALC) is utilized. After compensating the delay, the output power of the EVs is calculated and collaborated in frequency regulation. In addition, an algorithm is proposed for collaborating VSWT in frequency control. In the proposed algorithm, according to the wind velocity, the output power of the VSWT increases to the maximum acceptable value and will be fixed. A method is developed to find the maximum acceptable increment power considering VSWT constraints. After a supportive part, a recovery part is started to return VSWT hub speed to a desired value. Two PID controllers are designed in this algorithm for support and recovery parts. During the recovery part, a second frequency dip emerges and a method is introduced which at first identifies the second frequency dip moment and EVs collaboration is applied to alleviate this unfavorable outcome. To evaluate the performance of the proposed algorithms and controllers, different simulation studies are conducted using the modified IEEE 39-bus test power system. Results confirm the effectiveness of the proposed methods in system frequency support.

Novelty three stages for humification of sewage sludge during hyperthermophilic aerobic fermentation

Compared with conventional aerobic fermentation (CAF), there is limited knowledge of how hyperthermophilic aerobic fermentation (HAF) enhances the humification of sewage sludge. This study compared three novel stages of organic degradation, precursors, functional groups, bacterial community, and humus synthesis mechanism in HAF with CAF. The results showed that organic matter (OM) degraded rapidly, and 68% of the degradation could be completed of stage I in HAF. Compared with the initial stage, ammonium nitrogen (NH4+-N), water-soluble organic carbon, and water-soluble total nitrogen increased by 2.83 times, 40.5 times, and 33.5 times, respectively. Cellulose and hemicellulose decreased by 29.22% and 21.85%, respectively. These results suggested that temperature (>80 °C) and Bacillus dominated accelerate the humification process by rapidly improving OM degradation. Compared with the initial value of HAF, the maximum increment of reducing sugar at stage II was 297%, and the degradation rate of cellulose was effectively increased by 21.03% compared with that of CAF. The precursors such as reducing sugars and amino acids formed humus at stage II. The content of Aryl C increased significantly during the HAF process, the degree of polymerization of humus and the aromatization degree of HA and FA increased significantly, and complex organic macromolecular material polymers were formed at stage III. The sugar-amine condensation was the mechanism of humification in the sludge HAF process. This investigation provided three new stages of insights into the synthesis of humification during the HAF process and extended the current mechanism of humification in the HAF process.

Active and passive safety enhancement for batteries from force perspective

Thermal runaway (TR) has become a critical issue for Li-ion battery applications in electric vehicles and energy storage stations. To address this issue, early warning and thermal runaway propagation (TRP) mitigation are significant for the active and passive safety of the battery system, respectively. This study proposes the expansion force as a reliable warning signal, which is proven to provide more interval (>500 s) for escape and rescue compared with voltage and temperature signals. Besides, the TR expansion force changing mechanism due to thermal expansion, gas generation/accumulation, and venting is investigated. Furthermore, the TRP expansion force and deformation changing mechanism is explained from the perspective of expansion, squeeze, and venting. The TRP debris deformation trend is verified through mechanical modeling. The maximum TR expansion force increment (ΔFmax)-capacity (Q) equalization and ΔFmax-cell index equations are proposed based on the TR/TRP tests of three types of prismatic batteries. Moreover, a TRP mitigation structure is proposed to amplify the TR expansion force, which is validated to effectively amplify the force, causing the mechanical destruction of the in-line module holder. A TRP mitigation test proves that the first TR cell capsizes the module holder to hinder the heat transfer between the front/back surfaces of the prismatic batteries when the TR expansion force exceeds the preload. Without enough heat transfer, the TR of the following battery cells cannot be triggered even under jet fire impact. This study guides the active and passive safety design for the prismatic battery system.

Experimental and numerical investigation into locally corroded circular concrete-filled steel tubular stub columns strengthened by CFRP

Concrete-filled steel tube (CFST) is vulnerable to corrosion in service, especially local corrosion. Nevertheless, limited work has been conducted on the behaviors and strengthening methods of locally corroded CFSTs. This paper presents experimental and numerical investigations into the behavior of locally corroded CFST stub columns and locally corroded CFST stub columns strengthened by carbon fiber reinforced polymer (CFRP). Tests were conducted on thirteen specimens with local corrosion of steel tubes simulated by means of artificial notches, and the notch length and number of CFRP layers were chosen as test parameters. The test results revealed that the performance of the specimens strengthened by CFRP was significantly improved, compared with that of the unstrengthened specimens. The maximum compression resistance increment of the CFRP-strengthened specimens was up to 58.8%. Subsequently, finite element (FE) models were developed and verified by the experimental results. Based on the FE models, parametric analyzes were conducted to investigate the axial behavior of locally corroded circular CFST stub columns strengthened by CFRP. The parametric analysis results indicated that CFRP can compensate for the loss of confinement effect of steel tube caused by local corrosion. In addition, when the hoop force provided by CFRP is equal to that provided by the yield stress of steel tube, the compression resistance of locally corroded CFST stub columns strengthened by CFRP is even slightly higher than that of CFST stub columns without corrosion.