Average Specific Energy Research Articles

Numerical investigation on the influence of cutting parameters on rock breakage using a conical pick

To comprehensively understand the effects of roadheader cutting parameters on rock breakage, this paper conducts a numerical investigation of rock vertical indentation tests using a conical pick, utilizing the discrete element method (DEM). Three crucial cutting parameters, including cone angle, attack angle, and cutting depth, are analyzed as independent variables to elucidate their impact on rock breakage characteristics, such as peak cutting force and specific energy. The research results indicate that the ultimate failure of rock is primarily caused by the accumulation of microcracks from each local fracture, predominantly governed by tensile failure. As the cone angle increases, both the peak cutting force and specific energy exhibit a monotonic upward trend, while the maximum stress at the tip of the conical pick shows a fluctuating pattern. To achieve a balance between cost effectiveness and efficient rock breakage, an optimal cone angle range of 55° to 100° is recommended. The peak cutting force and specific energy decease exponentially as the attack angle increases, with an optimal range of 70° to 90°. Under continuous cutting conditions with a fixed total length of 60 mm, the average peak cutting force increases with cutting depth, while the average specific energy initially decreases and then increases, identifying an optimal cutting depth of 20 mm. These findings have significant engineering implications for optimizing the cutting parameters of roadheader to enhance the efficiency of mechanized excavation.

Innovative solar-assisted direct contact membrane distillation system: Dynamic modeling and performance analysis

The study presents an innovative solar-assisted dual-tank direct contact membrane distillation (DCMD) system designed to enhance the operational stability and efficiency of solar-powered desalination. The proposed system integrates a dual thermal storage tank configuration, allowing for continuous operation by alternating between two tanks that store pre-heated water, thereby mitigating the impact of solar energy fluctuations. The dynamic modeling approach used in this study predicts the system's performance under varying solar conditions, focusing on key parameters such as permeate flux, evaporation efficiency, and specific thermal energy consumption. The simulation results show that the system achieves an average permeate flux of 14.4 L/h m² and a thermal efficiency of 53.3 % at a hot water temperature of 60 °C, with a corresponding average specific thermal energy consumption of 1567 kWh/m³. These findings highlight a substantial improvement in both thermal efficiency and water production compared to conventional single-tank systems.The dual-tank DCMD system is particularly suited for deployment in remote or arid regions where stable and efficient freshwater production is critical. This research provides a comprehensive analysis of a novel solar-assisted desalination technology, contributing to the advancement of sustainable water resources management by providing a reliable and scalable solution that can maintain high operational efficiency even in remote areas with variable solar conditions.

Simulation of a Tidal Current-Powered Freshwater and Energy Supply System for Sustainable Island Development

Sustainable development of islands cannot be achieved without the use of renewable energy to address energy and freshwater supply issues. Utilizing the widely distributed tidal current energy in island regions can enhance local energy and water supply security. To achieve economic and operational efficiency, it is crucial to fully account for the unique periodicity and intermittency of tidal current energy. In this study, a tidal current-powered freshwater and energy supply system is proposed. The marine current turbine adopts a direct-drive configuration and will be able to directly transfer the power of the turbine rotation to the seawater pump to improve the energy efficiency. Additionally, the system incorporates batteries for short-term energy storage, aimed at increasing the capacity factor of the electrolyzer. A simulation is conducted using measured inflow velocity data from a full 12 h tidal cycle. The results show that the turbine’s average power coefficient reaches 0.434, the electrolyzer’s average energy efficiency is 60.9%, the capacity factor is 70.1%, and the desalination system’s average specific energy consumption is 6.175 kWh/m3. The feasibility of the system design has been validated.

Two-stage microreactor with intensely swirling flows: Comparison of three methods of liquids feeding

A two-stage microreactor with intensely swirling flows (MRISF-2) allows to perform effectively two subsequent reactions in synthesis of nanosized particles. Micromixing quality plays crucial role in ultrafast co-precipitation reactions, and depends both on the specific energy dissipation rate and on the geometry of the reactor as well as the solutions feeding manner. Solutions in MRISF-2 could be supplied by different ways: through the upper and/or lower tangential inlet pipes and through the central (axial) inlet pipe. This paper is aimed to compare experimentally and numerically three ways of liquid solutions feeding in MRISF-2 with objective to find the conditions of the highest specific energy dissipation rate. The best method of solutions supplying was found experimentally and confirmed numerically: one solution is supplied tangentially, the other through the central inlet pipe. The average specific energy dissipation rate for this method is 1.7 and 6.0 times higher compared to supply through two upper tangential inlet pipes and upper + lower tangential inlet pipes, respectively. This advantage was confirmed by measurements of segregation index Xs by use of iodide-iodate reaction technique. Good agreement between experimental and numerical simulation results for energy dissipation rate was found for all studied cases.

Drilling performance of Al-Ni eutectic alloy with scandium addition

Al-Ni eutectic alloys are an alternative alloy for high-temperature applications because of their excellent thermal stability of the Al3Ni eutectic fibers. Since the matrix of eutectic Al-Ni is weak, adding Sc to the alloy (Al-6Ni-0.4Sc) is able to increase its strength and hardness. This study is to investigate the machinability of Al-6Ni-0.4Sc alloy compared to Al-6Ni alloy through a drilling process. The results revealed that the Al-6Ni-0.4Sc alloy required less power, torque, and thrust force in the drilling process than Al-6Ni, despite having higher strength and hardness. The average specific energy for the drilling of Al-6Ni-0.4Sc alloy was 1.011 W s/mm3. This was 12.77% less than the value for Al-6Ni alloy. The chip velocity in the drilling of the alloy with Sc addition was twice that of the alloy without Sc, implying low heat accumulation in the cutting tool, less tendency for built-up edge formation, and a low wear rate on the drill’s rake face when drilling Al-6Ni-0.4Sc alloy.

Facile synthesis and electrochemical investigation of graphitic carbon nitride/manganese dioxide incorporated polypyrrole nanocomposite for high-performance energy storage applications

Abstract Manganese dioxide (MnO2) nanoparticles were modified by graphitic carbon nitride (GCN) and polylpyrrole (Ppy) to enhance their electrochemical performance. The surface influence, crystalline structure, and electrochemical performance of the Ppy/GCN/MnO2 material were characterized and compared with those of pristine MnO2. It is found that surface modification can improve the structural stability of MnO2 without decreasing its available specific capacitance. The electrochemical properties of synthesized Ppy/GCN/MnO2 electrode were evaluated using cyclic voltammetry (CV) and AC impedance techniques in 5 M KOH electrolyte. Specific capacitances of 486, 815, 921, and 1377 F/g were obtained for MnO2, Ppy/MnO2, GCN/MnO2, and Ppy/GCN/MnO2, respectively, at 5 A/g. This improvement is attributed to the synergistic effect of GCN and Ppy in the Ppy/GCN/MnO2 electrode material. The Ppy/GCN/MnO2 electrode in KOH has average specific energy and specific power densities of 172 Wh kg−1 and 2065 W kg−1, respectively. Only 2 % of the capacitance’s initial value is lost after 10,000 cycles. The resulting Ppy/GCN/MnO2 nanocomposite had very stable and porous layered structures. This work demonstrates that Ppy/GCN/MnO2 nanomaterials exhibit good structural stability and electrochemical performance and are good materials for supercapacitor applications.

A novel bifunctional particle electrode with abundant Fe/Fe3C and Fe-N-C sites to enhance the performance of electro-Fenton in degrading organic pollutant

Electro-Fenton (EF) technology emerges as a promising approach to address the treatment of persistent organic pollutants. Nevertheless, its practical implementation often comes with certain drawbacks, like the low H2O2 activation efficiency, poor pH adaptability, and difficult recycling of the catalysts. To this end, we introduced highly active Fe-N-C sites onto the surface of nitrogen-doped graphene, improved the chemical environment of its central Fe atoms with Fe/Fe3C nanoparticles, effectively regulated the multi-electron oxygen reduction process of the catalyst in the electrochemical reaction, and realized the efficient production and activation of H2O2 in the electro-Fenton process. The synthesized Fe/Fe3C@FeNG-1000 achieved efficient removal of refractory organic pollutants in neutral conditions. The rate constant of degradation for tetracycline hydrochloride (TC) in the electro-Fenton reaction system at pH 7 was recorded as 0.1011 min−1. Additionally, a removal rate of 67.4% for total organic carbon (TOC) was achieved in just 120 min. The treatment of actual wastewater also showed excellent performance, with an average specific energy consumption of 6.16 kWh kg−1 COD−1. Fe/Fe3C@FeNG-1000 can still achieve more than 90% degradation efficiency after 5 consecutive cycles of the experiment, showing excellent stability, and the catalyst can be conveniently retrieved via magnetic methods following the reaction. The results show that the Fe/Fe3C@FeNG-1000-EF system has a wide range of pH applicability, long-term stability and good recyclability, has a good application value in practical wastewater treatment.

Multiscale Characterization and Biomimetic Design of Porcupine Quills for Enhanced Mechanical Performance.

The mechanical properties of porcupine quills have attracted the interest of researchers due to their unique structure and composition. However, there is still a knowledge gap in understanding how these properties can be utilized to design biomimetic structures with enhanced performance. This study delves into the nanomechanical and macro-mechanical properties of porcupine quills, unveiling varied elastic moduli across different regions and cross sections. The results indicated that the elastic moduli of the upper and lower epidermis were higher at 8.13 ± 0.05 GPa and 7.71 ± 0.14 GPa, respectively, compared to other regions. In contrast, the elastic modulus of the mid-dermis of the quill mid-section was measured to be 7.16 ± 0.10 GPa. Based on the micro- and macro-structural analysis of porcupine quills, which revealed distinct variations in elastic moduli across different regions and cross sections, various biomimetic porous structures (BPSs) were designed. These BPSs were inspired by the unique properties of the quills and aimed to replicate and enhance their mechanical characteristics in engineering applications. Compression, torsion, and impact tests illustrated the efficacy of structures with filled hexagons and circles in improving performance. This study showed enhancements in maximum torsional load and crashworthiness with an increase in filled structures. Particularly noteworthy was the biomimetic porous circular structure 3 (BPCS_3), which displayed exceptional achievements in average energy absorption (28.37 J) and specific energy absorption (919.82 J/kg). Finally, a response surface-based optimization method is proposed to enhance the design of the structure under combined compression-torsion loads, with the goal of reducing mass and deformation. This research contributes to the field of biomimetics by exploring the potential applications of porcupine quill-inspired structures in fields such as robotics, drive shafts, and aerospace engineering.

Electrochemical evaluation and structural characterization of polythiophene surfaces modified with PbO/PbS for energy storage applications

Polythiophene (PTh) was modified with nanoparticles of lead oxide (PbO) and lead sulfide (PbS) to enhance its electrochemical performance. The surface characteristics, crystalline structure, and electrochemical behavior of the PTh/PbO/PbS material were analyzed and compared with pristine PTh. Surface modification was found to enhance the structural stability of PTh without compromising its specific capacitance. The electrochemical properties of the synthesized PTh/PbO/PbS electrode were assessed using cyclic voltammetry (CV) and AC impedance techniques in a 3 M KOH electrolyte. Specific capacitances of 245, 620, 716, and 992 F/g were achieved for PTh, PTh/PbO, PTh/PbS, and PTh/PbO/PbS, respectively, at 5 A/g. This enhancement is attributed to the synergistic effect of Pb2+ ions in the PTh/PbO/PbS electrode material. The PTh/PbO/PbS electrode in KOH exhibited average specific energy and specific power densities of 972 Wh kg−1 and 6086 W/kg, respectively, with only a 4% decrease in capacitance after 10000 cycles. The resulting PTh/PbO/PbS nanocomposite displayed highly stable and porous layered structures. This study underscores the favorable structural stability and electrochemical performance of PTh/PbO/PbS nanomaterials, positioning them as promising materials for supercapacitor applications.

Studies on improved stability and electrochemical activity of metal oxides/sulfides‐based polymer nanocomposites for energy storage applications

AbstractPoly (3‐methylthiophene) (P3MT) was modified by nickel oxide (NiO) and nickel sulfide (NiS) nanoparticles to enhance its electrochemical performance. The surface influence, crystalline structure, and electrochemical performance of the P3MT/NiO/NiS material were characterized and compared with that of pristine P3MT. It is found that surface modification can improve the structural stability of P3MT without decreasing its available specific capacitance. The electrochemical properties of synthesized P3MT/NiO/NiS electrode were evaluated using cyclic voltammetry and alternating current impedance techniques in 3 M KOH electrolyte. Specific capacitances of 253, 764, 932, and 1434 F g−1 were obtained for P3MT, P3MT/NiO, P3MT/NiS, and P3MT/NiO/NiS, respectively at 5 A g−1. This improvement is attributed to the synergistic effect of Ni2+ ions in the P3MT/NiO/NiS electrode material. The P3MT/NiO/NiS electrode in KOH has average specific energy and specific power densities of 1032 Wh kg−1 and 6192 W/kg, respectively. Only 2% of the capacitance's initial value is lost after 10,000 cycles. The resulting P3MT/NiO/NiS nanocomposite had very stable and porous layered structures. This work demonstrates that P3MT/NiO/NiS nanomaterials exhibit good structural stability and electrochemical performance, and are good material for supercapacitor applications.Highlights The P3MT/NiO/NiS nanocomposite is fabricated and characterized as supercapacitor electrode. The incorporation of NiO/NiS in the poly (3‐methylthiophene) has improved the electrochemical performance. The P3MT/NiO/NiS electrodes retained 98% of their specific capacitance after 10,000 cycles. The P3MT/NiO/NiS nanocomposite electrode showed specific capacitance of 1434 F g−1 at 5 A g−1. The stability of the nanocomposite was enhanced without altering its morphology and chemical structure.

Exploring the effects of a warmer climate on power and energy demand in multi-family buildings in a Nordic climate

The need to understand how a warmer climate affects the power and energy demand in cold countries is important for urban planners and policymakers. By using data from utility bills that are commonly available today, together with outdoor temperatures, it is possible to analyze historical and future power and energy demand. The scientific value of this research includes the development of a methodology to explore effects on future heat demand in the Nordic region based on a combination of historical data, building properties, and predictions of future climate. This is achieved by using an energy signature model and regression analysis. Seventy multi-family buildings in Linköping, Sweden, are investigated from 1980 to 2050. The results show that the effects from historical variations in internal heat gains (average annual increase of 1 %) on the specific energy use for space heating (SPH) is minor for the district, i.e., less than 2 % when comparing 2020 and 1980. The opposite is found for variations in outdoor temperatures, where the average specific energy use is predicted to decrease by about 25 % in 2050 compared to 1980, with the used forecast of future climate. This corresponds to a decrease from 127 kWh/(m2·year) to 93–96 kWh/(m2·year). Additionally, the maximum heating power demand of the district is predicted to decrease by about 30 %, from 4,855 kW in 1980 to 3,468 kW in 2050. In conclusion, our results demonstrate a strong effect of decreased SPH and heating power demand in residential districts due to a warmer climate.

Long‐term outdoor study of an organic photovoltaic module for building integration

AbstractOrganic photovoltaics (OPV) has attracted tremendous attention as a promising alternative to silicon wafer‐based technologies for building integration. While significant progress has been achieved on the power conversion efficiency of OPV technologies, their field stability is rarely studied. This work investigates the field performance and reliability of a large‐area OPV module designed for building integration in tropical Singapore for 4.5 years. The device suffered more than 14% degradation in power at the standard testing conditions from the initial performance, largely due to losses in fill factor (−12% relative). During the monitoring period, it exhibited comparable performance to more conventional silicon PV technologies, with an average specific energy yield of about 4 kWh/kWp/day and an average performance ratio of 0.96. Excellent performance at low light conditions was also observed. However, its field performance was heavily impacted by soiling, which typically led to a 5 to 10% loss in the current output after several months. Further, the device's outdoor performance also showed a three‐stage degradation process, including (1) an initial slow degradation in the first 2 years (about −1%/year), (2) a stable period with negligible performance loss from Years 2 to 3.5, and (3) a rapid degradation in the last year (about −5%/year).

Synthesis and characterization of polypyrrole/graphitic carbon nitride/niobium pentoxide nanocomposite for high‐performance energy storage applications

AbstractGraphitic carbon nitride (GCN) has been employed as a supercapacitor electrode because of its high carbon‐to‐nitrogen ratio and flexible structure. However, its low surface area and poor conductivity continue to be obstacles for practical usage. GCN's electrochemical characteristics are enhanced by the hybrid structure it forms with polypyrrole and Nb2O5. The synthesized polypyrrole (Ppy)/GCN/niobium pentoxide (Nb2O5) (Ppy/GCN/Nb2O5) nanocomposite electrode was tested for supercapacitance by cyclic voltammetry (CV) and Alternating current impedance techniques in 6 M Potassium hydroxide(KOH) electrolyte. The Ppy/GCN/Nb2O5 is linked to a network of agglomerated GCN and Nb2O5 nanoparticles with additional spherical shapes. The specific capacitance of Ppy/GCN/Nb2O5 was determined to be 1177 Fg−1 at a current density of 5 Ag−1. The Ppy/GCN/Nb2O5 electrode in KOH has average specific energy and specific power densities of 33 Wh kg−1 and 2991 W kg−1, respectively. The electrode showed excellent capacitance‐retention ability of 97% after 10,000 cycles. The results demonstrate the high stability and efficient performance of the Ppy/GCN/Nb2O5 electrode employed in supercapacitors. The performance of the Ppy/GCN/Nb2O5 electrode was found to be superior to those reported for other carbon‐based materials.

A FINITE ELEMENT ANALYSES OF THE EFFECT OF HYDROSTATIC PRESSURE IN A THIN ADHESIVE LAYER ON ITS FRACTURE UNDER MIXED-MODE LOADING

The problem of deformation of a sample, which is a composition of orthotropic bodies bound by an adhesive layer, realizing a mixed loading mode I + II for the layer material in the vicinity of a crack-like defect, is considered. A crack-like defect in a composite was considered both in the form of a mathematical section and a physical section, the thickness of which was considered as a linear parameter. A finite element solution with an elastic description of materials in a state of plane deformation is used. To find critical states, the values of specific elastic energy in the tip of a crack-like defect were analyzed. So, for the mathematical section, the values of energy were associated with stress intensity factors and for the physical section with the energy product in the form of the product of a linear parameter and the average specific free energy on the face of a dead-end finite element of the adhesive layer. Finding the characteristics averaged over the layer thickness was determined within the framework of the Neuber – Novozhilov approach. For a small finite value of the linear parameter the convergence of the energy product to the critical value of the specific elastic energy found for the crack model in the form of a mathematical cut is shown for equivalent loading of the sample with a physical cut and the linear parameter tends to zero. For an adhesive layer of finite thickness an energy fracture criterion is considered which takes into account the loosening of the material due to hydrostatic pressure. The loosening of the material was taken into account by the parameter which was determined from the solution of the problem of normal tension of the adhesive layer by the cantilevers of the two-cantilever beam taking into account the critical values of the specific elastic energy. A comparison is made of the calculated critical external load for the formulation of the problem using a layer of finite thickness and the classical representation of a crack-like defect in the form of a mathematical section and a layer of zero thickness under the appropriate failure criteria.

Multiscale Monte Carlo simulations for dosimetry in x-ray breast imaging: Part II - Microscopic scales.

Although the benefits of breast screening and early diagnosis are known for reducing breast cancer mortality rates, the effects and risks of low radiation doses to the cells in the breast are still ongoing topics ofstudy. To study specific energy distributions ( ) in cytoplasm and nuclei of cells corresponding to glandular tissue for different x-ray breast imagingmodalities. A cubic lattice (500 μm length side) containing 4064 spherical cells was irradiated with photons loaded from phase space files with varying glandular voxel doses ( ). Specific energy distributions were scored for nucleus and cytoplasm compartments using the PENELOPE (v. 2018) + penEasy (v. 2020) Monte Carlo (MC) code. The phase space files, generated in part I of this work, were obtained from MC simulations in a voxelized anthropomorphic phantom corresponding to glandular voxels for different breast imaging modalities, including digital mammography (DM), digital breast tomosynthesis (DBT), contrast enhanced digital mammography (CEDM) and breast CT (BCT). In general, the average specific energy in nuclei is higher than the respective glandular dose scored in the same region, by up to 10%. The specific energy distributions for nucleus and cytoplasm are directly related to the magnitude of the glandular dose in the voxel ( ), with little dependence on the spatial location. For similar values, for nuclei is different between DM/DBT and CEDM/BCT, indicating that distinct x-ray spectra play significant roles in . In addition, this behavior is also present when the specific energy distribution ( ) is considered taking into account the GDD in thebreast. Microdosimetry studies are complementary to the traditional macroscopic breast dosimetry based on the mean glandular dose (MGD). For the same MGD, the specific energy distribution in glandular tissue varies between breast imaging modalities, indicating that this effect could be considered for studying the risks of exposing the breast to ionizingradiation.

ВПЛИВ ШВИДКОСТІ ТРАНСПОРТУВАННЯ ВАНТАЖУ СТРІЧКОВИМ КОНВЕЄРОМ НА ПИТОМЕ ЕНЕРГОСПОЖИВАННЯ НА КОНВЕЄРНОМУ ТРАНСПОРТІ

The method of work is significant to the nature and approximation of the empirical supply of feedstock energy consumption for the transport of dry waste by a string conveyor, which operates in the drains of the DolzhanskaKapitalna mine, due to the speed of transport of waste. Significant energy consumption for transporting goods is an unknown warehouse assessment of the technical level of the stitch conveyor, which is a current scientific and practical requirement. The article examines the non-linear nature of the dependence of weighted average specific energy consumption for the transportation of bulk cargo by a mine belt conveyor on the speed of cargo transportation. The function of the weighted average specific energy consumption for the transportation of bulk cargo by a belt conveyor is obtained in a theoretical way using the method of technological calculation of a mine belt conveyor. The influence of the unevenness of the cargo flow on the conveyor on the formation of weighted average specific energy consumption was carried out empirically using the results of studies of the cargo flow and the power consumption of the belt conveyor of the "Dolzhanska-Capitalna" mine, conducted in 2011 by the "Dongiprovuglemash" institute. Using the method of least squares, empirical coefficients of the approximated dependence of the weighted average specific energy consumption for the transportation of bulk cargo by a belt conveyor of a mining enterprise on the speed of cargo transportation, which has the form of a square trinomial, were obtained. The results of the work can be determined by designing the conveyor transport of mining enterprises, determining the energy intensity and technical level of the mine stitch conveyor, and clarifying the nature of the mechanical characteristics of the stitch conveyor

Fabrication of polythiophene/graphitic carbon nitride/V2O5 nanocomposite for high-performance supercapacitor electrode

In this study, an in-situ oxidation polymerization approach and a surface adsorption procedure were combined to create a polythiophene/graphitic carbon nitride (GCN)/vanadium pentoxide (V2O5) (PTh/GCN/V2O5) nanocomposite. Investigations were made on the nanomorphology and crystal structure of PTh, PTh/GCN, PTh/V2O5, and PTh/GCN/V2O5. The main objective of this investigation is to evaluate the electrochemical performance of the developed PTh/GCN/V2O5 electrode for supercapacitor application using cyclic voltammetry (CV) and AC impedance techniques in 3 M KOH electrolyte. The PTh/GCN/V2O5 nanocomposite's average crystallite size is 50 nm. The PTh/GCN/V2O5 has a network of agglomerated GCN and V2O5 nanoparticles with extra spherical forms that are associated to PTh. Their absorption intensities improve with the creation of the PTh/GCN/V2O5 nanocomposite. The specific capacitance of PTh/GCN/V2O5 in 3 M KOH was determined to be 720 F/g at a current density of 5 A/g. The PTh/GCN/V2O5 electrode in KOH has average specific energy and specific power densities of 32 Wh kg−1 and 3291 W kg−1, respectively. Only 4 % of the capacitance's initial value is lost after 5000 cycles. The results demonstrate the PTh/GCN/V2O5 electrode utilised in supercapacitors' exceptional stability and efficient functioning.

Employing low dissolved oxygen strategy to simultaneously improve nutrient removal, mitigate membrane fouling, and reduce energy consumption in an AAO-MBR system: Fine bubble or coarse bubble?

The high energy consumption associated with aeration, which is a widely used hydrodynamic method to mitigate membrane fouling in membrane bioreactors (MBR), poses a significant challenge to the widespread application of aerated MBR. In this study, low dissolved oxygen was applied to optimize the overall performance and reduce energy consumption in an anaerobic-anoxic-aerobic MBR (AAO-MBR) under fine and coarse bubble aeration conditions. Coarse bubble aeration exhibited better membrane fouling control, but induced releasing more proteins and polysaccharides in mixed liquor than that in fine bubble aeration. Coarse bubble aeration resulted in a decrease in the relative abundance of function bacteria, and there was a corresponding drop in enzymes involved in the nitrogen and phosphorus pathways. Furthermore, the average total specific energy demand (0.45 ± 0.02 kW·h/d) and total carbon emissions (0.32 ± 0.01 kg/d) of coarse bubble aeration was remarkably higher than that of fine bubble aeration (0.35 ± 0.01 kW·h/d and 0.25 ± 0.02 kg/d). Our results demonstrate that the fine bubble aeration in low dissolved oxygen-based AAO-MBR can optimize the overall performance and reduce energy consumption, thereby making it a more viable option for the wastewater treatment.

Flexural behaviors and failure mechanisms of CFRP sandwich structures with enhanced dual-phase lattice cores

Inspired by bionic/metallurgical microstructures, novel dual-phase lattice/ Carbon Fiber Reinforced Polymer (CFRP) composite sandwich structures are proposed to improve the energy absorption (EA). The composite sandwich structures for different dual-phase strengthening strategies are designed, where the topology optimization is used to yield efficient lattice distribution configurations. The experimental samples are fabricated by 3D-printing and three-point bending tests are conducted. The flexural failure process and failure modes are observed and analyzed to reveal the failure mechanisms. Results show that DPL-1-CFRP and DPL-2-CFRP have higher peak load (+24.8 % and 18.0 %), post-peak average load (42.6 % and 20.8 %) and specific energy absorption (+7.8 % and + 21.1 %) compared to SPL-1-CFRP. It is indicated that the interactive failure mechanism of dual-phase lattice is effective in improving the mechanical properties of sandwich structure. It represents the occurrence of synergistic deformation between struts rather than a single brittle fracture. Finally, several potential failure mechanisms for the separation of the core and end faces are revealed. This novel concept and structural design greatly contribute to improve mechanical properties of sandwich structure.

A novel method of fabricating aluminium honeycomb core by friction stir welding

Aluminium honeycomb structure has been recognized as an exceptional lightweight energy absorber in transportation, construction and aerospace industries. An innovative fabrication method based on friction stir welding is proposed to enhance the crashworthiness property of aluminium honeycomb and address the challenges with conventional fabrication methods. Moreover, a lab-scale fixture is designed to demonstrate the feasibility of the suggested method for industrial use. Various fabricated honeycombs with different core heights and cell counts are subjected to quasi-static flatwise compression tests to investigate their crushing characteristics. The crashworthiness parameters like yield stress, average plateau stress, specific energy absorption are analysed and compared with theoretically predicted crushing strength. The failure mode of the structure is also discussed, showing the influence of non-optimal welding parameters. Experimental results indicate that average crush force and specific energy absorption do not differ significantly with cell count and core height. The specimens under flatwise compression fold with plastic hinges symmetrically positioned without any rupture of the weld. Specific compression property of the fabricated honeycomb has been compared with other aluminium honeycombs fabricated using other methods, which favours the friction stir welded honeycomb over the other conventional counterparts.