Flux Stability Research Articles

Poly(aryl ether ketone) hollow fibers preparation with acid resistant spinnerets

Poly(ether ketone ketone) (PEKK) and poly(ether ether ketone) (PEEK) are high-performing thermoplastics applicable for solvent-resistant nanofiltration due to their outstanding resistance to harsh conditions. However, the polymers require strong acids for solubilization and use as dope solution for membrane preparation. This is the major limitation when targeting hollow fibers (HF) since the metallic spinning line and spinnerets could be prone to corrosion in long term. In this work, we propose the fabrication of an acid-resistant spinneret by 3D printing technology through stereolithography using acrylate and methacrylate-based resins. The hollow fibers are produced by interplaying spinneret designs and spinning conditions with an acid-resistant spinning line. The fabricated hollow fibers exhibited N,N-dimethylformamide (DMF) permeance of 1.4–2.7 L m−2 h−2 bar−1, with a molecular weight cut-off around 246 g mol−1 confirmed with more than 90% rejection of 1,3,5-tri-tert-butyl benzene (TTBB). Furthermore, the hollow fiber modules were tested at high-temperature filtration in DMF with confirmed membrane flux or structural dimension stability.

Synthesis, characterization, and application of gravity-driven ceramic microfiltration membranes for surface water treatment

Gravity-driven ceramic microfiltration (MF) disk-shaped membranes were synthesized using kaolin and different alumina contents (0 % wt, 25 % wt, and 50 % wt). The pure water flux, mean pore size, porosity and contact angle of membranes were measured. Their structure and composition were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of alumina content was evaluated for long-term river water filtration in terms of permeate flux, turbidity, dissolved organic carbon (DOC), UV254, pH, and alkalinity removal. The physical characteristics of the biofouling layer, such as thickness and roughness, were studied using optical coherence tomography (OCT) imaging and the concentration of active microorganisms in the biofilm. The results showed acceptable turbidity removal after the flux stabilization period and relatively high performance for DOC, UV, and alkalinity removal during the first three days of filtration. Flux stabilized at 2.5–3 LMH on day 24 of filtration, indicating that the alumina content does not considerably affect the stable flux. As the flux modeling data showed, prior to the flux stabilization time, the fouling was controlled by the pore blocking mechanism. This was confirmed by OCT imaging that showed a very outspread biofilm layer with a low relative roughness; the layer became more compact with a higher relative roughness over time, showing that the cake layer is dominant after the flux stabilization period. Increasing the alumina content of the membranes increased the number of active microorganisms in the biofilm layer; possibly because of an increased adsorption of nutrients in the biofouling layer.

Impacts of extreme climatic events on trophic network complexity and multidimensional stability.

Untangling the relationship between network complexity and ecological stability under climate change is an arduous challenge for theoretical and empirical ecology. Even more so, when considering extreme climatic events. Here, we studied the effects of extreme climatic events (heatwaves) on the complexity of realistic freshwater ecosystems using topological and quantitative trophic network metrics. Next, we linked changes in network complexity with the investigation of four stability components (temporal stability, resistance, resilience, and recovery) of community's functional, compositional, and energy flux stability. We found reduction in topological network complexity to be correlated with reduction of functional and compositional resistance. However, temperature-driven increase in link-weighted network complexity increased functional and energy flux recovery and resilience, but at the cost of increased compositional instability. Overall, we propose an overarching approach to elucidate the effects of climate change on multidimensional stability through the lens of network complexity, providing helpful insights for preserving ecosystems stability under climate change.

Structure preserving discontinuous Galerkin approximation of one-dimensional port-Hamiltonian systems

In this article, we present the structure preserving discretization of linear one-dimensional port-Hamiltonian (PH) systems of two conservation laws using discontinuous Galerkin (DG) methods. We recall the DG discretization procedure which is based on a subdivision of the computational domain, an elementwise weak formulation with up to two integrations by parts, and the interconnection of the elements using different numerical fluxes. We present the interconnection of the element models, which is power preserving in the case of conservative (unstabilized) numerical fluxes, and we set up the resulting global PH state space model. We discuss the properties of the obtained models, including the effect of the flux stabilization parameter on the spectrum. Finally, we show simulations with different parameters for a boundary controlled linear hyperbolic system.

Investigation of Thermophysical and Physicochemical Characteristics of Al2O3-SiO2- CaO - Na3AlF6 Flux for SMAW Electrode Coating

This study investigated the thermophysical, physicochemical, and electrical characteristics of electrode coatings developed for application in the weld joint of nuclear power plants (NPPs). The extreme vertices design technique has been used in this work to develop the Al2O3-SiO2-CaO-Na3AlF6-based Shielded metal arc welding (SMAW) electrodes. Twenty-six electrode coating compositions were formulated, and flux coatings were milled into a fine powder for further characterization. X-ray diffraction (XRD) technique was utilized to investigate the structure and phases of the coating composition, and the Fourier transform infrared (FTIR) analysis technique was employed to determine the nature of bonds. The coating's thermal characteristics, including conductivity, diffusivity, and specific heat, were evaluated using hot disk equipment. Enthalpy change and thermal stability of flux coating were determined using the Differential thermal analysis(DTA)/ differential scanning calorimetry (DSC) technique.. The precision inductance (L), capacitance (C), and resistance (R) (LCR) instrument was used further to examine the electrical characteristics of the flux coatings. In addition, a regression model has been developed for each coating property using statistical analysis and investigated a correlation between the properties and mineral interactions. Results reveal that the individual elements and their binary and tertiary interaction significantly influence the physicochemical, thermophysical, and electrical properties of the flux coatings.

Recovering and reuse of textile dyes from dyebath effluent using surfactant driven forward osmosis to achieve zero hazardous chemical discharge

This experimental study explores the feasibility of the reuse of dyes recovered from denim and polyester dyebath effluents using forward osmosis (FO) system to achieve zero hazardous material discharge. In batch experiments, the sodium dodecyl sulfate (SDS) at 0.5 M concentration generated an average flux of 3.5 L/m2/h (LMH) and reverse salt flux (RSF) of only 0.012 g/m2/h (GMH), while maintaining 100% dye rejection. This flux stability comes from the property of surfactants to form micelles and exert a stable osmotic pressure (π) above their critical micelle concentration (CMC). The low RSF is due to the greater micelle size. A colored fouling layer was formed on the membrane active layer (AL), which was easily removed using sodium hydroxide (NaOH) and citric acid. According to Fourier transform infrared spectra and atomic forces microscopy images of the AL, the interaction between foulants and membrane active groups did not significantly affect the physiochemical properties of the membrane. In the semi-continuous experiment, a very stable average flux of 7.3 LMH and RSF of 0.03 GMH was obtained using 0.75 M SDS as draw solution. The stacked 1D proton nuclear magnetic resonance analysis (1HNMR) spectra of both original and recovered disperse dyes showed 100% similarity, which validates the concept that the recovered dyes maintained their integrity during reconcentration and can be reused in the next batch dyeing process. Importantly, the diluted SDS concentration can be directly reused within the same textile industry in scouring and finishing processes. The processes of dye recovery and reuse developed in this study do not produce any waste or hazardous by-products and are suitable for scale-up and onsite industrial applications.

FEATURES OF THE FIELD WEAKENING MODE IN А SWITCHED RELUCTANCE MACHINE

The magnetic field weakening mode of electric machines is used in modern drives to extend the drive operational speed range when the power supply voltage is limited. In conventional electric drives, a real or fictitious flux control loop, established in a vector control system by using coordinate and phase transformations of corresponding variables, is used for attenuating the motor magnetic flux. Switched reluctance machines have certain design advantages over conventional electric machines; they feature high reliability and wide control possibilities. However, to realize these possibilities, appropriate control outputs should be generated, the choice of which depends on the operational speed range. Another peculiarity of these machines is that there is no separate magnetic flux stabilization or control circuit. The article considers the specific features pertinent to the switched reluctance machine operation in various speed ranges for adequately taking them into account in control algorithms. The studies were carried out using the electric drive simulation model in the MATLAB Simulink environment. It is shown that during the electric drive operation at its limit mechanical characteristic in the low-speed zone under the speed variation conditions, the phase flux linkage average value can be considered almost unchanged. However, control of the average torque carried out by changing the current limitation level is performed at the magnetic flux weakening background. It has been determined that during operation in a high-speed zone at invariable phase switching positions with the speed growing in a natural manner (i.e., without applying control actions), there is an excessive decrease in the flux linkage average value, which leads to a dramatic drop in the phase average torque. This drop can be compensated by progressively shifting the phase engagement position in the leading direction.

Antifouling forward osmosis membranes by ε-polylysine mediated molecular grafting for printing and dyeing wastewater: Preparation, characterization, and performance

Membrane fouling during forward osmosis (FO) seriously affects the service life of the membrane and increases the treatment cost. A facile strategy was developed to mitigate membrane surface fouling and simultaneously achieve high pollutants rejection. The amino group on ε-Polylysine (PL) reacted covalently with the active sites (acyl chloride and carboxyl group) on the polyamide (PA), thereby grafting the ε-PL onto the PA active layer of PAN/LiCl supported membrane. Effects of membrane orientation, concentration of draw solution (DS), and pH of feed solution (FS) on pollutants rejection were investigated. Results showed that rejection efficiencies of TOC, Ca, Mg, Sb, Cr, and aniline in wastewater by the 0.5 wt% PL-grafted PAN-1.5LiCl TFC-FO membrane (FO-0.5 PL) attained 93.3%, 96.7%, 99.3%, 98.3%, 99.9%, and 99.8%, respectively. The high rejection efficiencies were mainly attributed to the improvement of the surface hydrophilicity of the grafted membrane, the reduction of the roughness, and the improvement of membrane surface potential. The microbubble-assisted cleaning experiment showed that the flux recovery efficiency of the FO-0.5 PL membrane could reach 98.8%, which is 6% higher than that of the FO-P membrane. The PL-grafted FO membrane simultaneously improves the stability of permeation flux (15.2 L m−2 h−1) and fouling resistance performance of the membrane. This study revealed that the PL grafted method can improve the antifouling performance of the membrane and can be used as a feasible treatment method for printing and dyeing wastewater. The research results provided a new idea for facile preparation and application of FO membranes and had a certain reference value for the development of antifouling FO membrane.

Effects of electromagnetic compound field on the dendrite growth of laser cladding

A single steady magnetic field (SMF) and an electromagnetic compound field with downward Lorentz force (EDLF) were applied to laser cladding process. The influence of the electromagnetic compound field on the dendritic growth was investigated. The microstructure of the dendrites was characterized using optical microscopy (OM) and electron backscatter diffraction (EBSD). It is shown that both SMF and EDLF can result in the grains coarsening, and the effect of EDLF is greater than that of SMF. With 1.2 T EDLF, large angle grain boundary (>10°) frequency is depressed. The velocity distribution, heat flux distribution and solidification interface cooling rate were also studied with a 2D multi-physics model. The results show that the velocity of molten pool is suppressed by the magnetic field and the solidification interface becomes flat when EDLF is applied. The suppression flow of the molten pool decreases the dendrite nucleation rate and improves the heat flux stability of the solidification front, which results in the enlarged gain size and improved grain texture. Small-curvature solidification interface occurs with the application of the EDLF, which can reduce the competition for the growth dendrite, and the grains of the cladding layer become coarser than the case of the application of the SMF.

Stability of carbon pools and fluxes of a Technosol along a 7-year reclamation chronosequence at an asbestos mine in Canada

Improved land stewardship is necessary for climate change mitigation. As such, actions are needed to increase carbon (C) sinks and reduce C emissions from land use activities. Residual materials with fertilizing capacity can be used to reconstruct severely degraded soils and recreate a sustainable vegetation cover, leading to reductions in atmospheric CO2 levels. We studied the temporal dynamics of CO2 sequestration potential in soils reconstructed with 1200 Mg ha−1 biosolids along a young chronosequence ranging from 0 to 7 years after initiating reclamation of a decommissioned asbestos mine in southern Québec, Canada. We measured in situ soil CO2 fluxes, soil C pools and soil physicochemical properties. Since bacterial communities are highly responsive to soil physicochemical properties, we also analyzed both their diversity and community structure. The age since soil reclamation did not have a clear effect on soil properties, but it exerted greater control over soil C fluxes and soil bacterial community diversity and structure. Our results suggest large C fluxes to the atmosphere within the first year following soil reconstruction, but soils constitute a stable C pool thereafter.

MODERN METHODS OF FINISHING AND HARDENING PROCESSING OF CYCLOIDAL HELICAL SURFACES

The paper analyzes the results of comparative studies of the lighting characteristics of LED filament lamps of the A60 type form factor from various manufacturers: luminous flux, power consumption, luminous efficiency, pulsation coefficient during the lamp burning time up to 6000 hours.Gorenje The test results show that the stability of the luminous flux after 6000 h of gorenje all LED filament lamps ranged from 91.3 to 96.4 %, which corresponds to the luminous flux stability code 9 according to GOST IEC 62612–2019, except for the Feron LB-57 7W 2700K lamp – 89.3 % (luminous flux stability code 8).

Enhanced permeability and stability of PVDF hollow fiber membrane in DCMD via heat-stretching treatment

Membrane distillation (MD) demonstrates excellent desalination application potential for high salt concentration wastewater. However, keeping the membrane flux and rejection high during long-term operation remains one of the critical challenges. In this work, a heat-stretching treatment method was proposed to improve the structure of polyvinylidene fluoride (PVDF) hollow fiber membrane and enhance its stability in the MD process. The membrane's pore size decreased after a heat-stretching treatment in water at 120 °C for 1 h. However, the liquid entry pressure of water (LEPw) value and membrane strength increased significantly, making it less prone to pore deformation during the drying or MD process and thus improving the membrane flux and stability in the MD process. The heat-stretching treatment made the PVDF chain arrangement more compact and oriented, avoiding shrinkage in the length direction. Besides stretching, the shrinkage of hollow fiber can be constricted by the combinedeffects of pore filling and stretching due to water or glycerol filling in the membrane pores, thus eliminating the capillary stress caused by liquid evaporation during the air-drying. Consequently, the heat-stretching treatment broke the trade-off between high permeate flux and high stability in the MD process.

Asymmetric Ba0.5Sr0.5Co0.8Fe0.2O3-Δ Membrane for Oxygen Permeation: Synergetic Fabrication By Magnetron Sputtering Deposition and Selective Laser Annealing

The Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) mixed ionic electronic conductor (MIEC) is considered to be one of the most promising perovskite-based materials for oxygen transport exhibiting high oxygen permeability. Such oxygen-permeable perovskite membrane maybe applied to increase efficiency of combustion or reforming processes of new fuels such as green ammonia. An approach to elevate the oxygen permeability of BSCF membranes is reduction of membrane thickness, as the permeation process is mostly controlled by bulk diffusion. Since self-standing thin membranes are not sufficiently mechanically stable, asymmetric membranes consisting of a thin layer membrane deposited onto a porous bulk support are usually employed. . In this work, planar BSCF thin film membranes of 1 to 2 and 15 to 20 µm thickness were successfully synthesized by a combination of magnetron sputtering (MS) and thermal annealing (TA) and/or selective laser annealing (SLA) processes. Thin films appeared to be pinhole-free with a high crystallinity of a single perovskite phase and a microstructure that showed suitability for oxygen permeation applications. Correlations between thin film properties and MS process parameters (e.g. power, Ar/O2 ratio, pressure, etc.) and TA&/SLA parameters were established and optimised as key factors for producing thin film membrane exhibiting high oxygen flux and good stability. A variation of the oxygen flux through the BSCF asymmetric membrane as well as the porous substrate is presented as a function of temperature and also oxygen partial pressures applied to both sides of the membrane allowing for calculation of permeability of the deposited thin film. Figure 1

Effects of organics concentration on the gravity-driven membrane (GDM) filtration in treating iron- and manganese-containing surface water

Iron and manganese contamination in the surface water is posing great challenges to the drinking water treatment supply, especially in the complex cases of organics involvement. Gravity-driven membrane (GDM) filtration equipped with the dual functions of ultrafiltration and biocake layer, conferred promising potentials in the removals of iron and manganese. This study evaluated the effects of organics concentrations on the removal performance of iron and manganese, as well as on the flux stabilization during GDM long-term filtration. The results indicated that stable flux level and the removal efficiency of manganese initially increased with the increase of organics concentration in the feed water, and then decreased. The moderate concentration of organic compounds in the feed water would positively facilitate the microbial activities and benefit to engineering a heterogeneous and porous biocake layer on the membrane surface, contributing to the highest improvements of stable flux (6.3 L m−2 h−1), while high concentration of organic compounds in the feed water would result in the increase in the thickness and EPS concentration of the biocake layer, leading to a flux reduction. Furthermore, the moderate concentration of organic compounds in the feed water was also beneficial to the manganese removal (> 94.6%) due to the more accumulation of auto-catalytic oxidation manganese oxides (MnOx) within the biocake layer and the improved biological degradation, however, further increase of organics concentration would deliver a negative impact on the manganese removal owing to the wrapping of MnOx by the organic substances. Overall, these findings provide practical and acceptable strategies to the selections of pre-treatments prior to GDM and promote its extensive application in treating the iron- and manganese-containing surface water.

Advanced method for clean water recovery from batik wastewater via sequential adsorption, ozonation and photocatalytic membrane PVDF-TiO2/rGO processes

This study aimed to investigate the synthesis of TiO2/rGO nanocomposite particles and incorporate them into PVDF membrane for Batik wastewater treatment. Bentonite adsorption and ozonation were combined to mitigate fouling development during the filtration process. The results proved that the TiO2/rGO nanocomposite successfully narrowed the band gap energy ∼2.9 eV by which enhancing its photo sensitivity within the visible light region. Furthermore, the chemical compatibility of TiO2 with PVDF can be improved with the presence of rGO. PVA coating on PVDF-TiO2/rGO membrane has enhanced hydrophilicity and provided the best performance by giving permeate flux ∼19.3 L.m−2.h−1 and dyes rejection up to ∼90%, respectively. Obviously, pre-treatment using bentonite and followed by ozonation significantly enhanced the permeate flux up to 21 L.m−2.h−1 and overall rejection up to ∼95%. As expected, the addition of TiO2/rGO nanocomposites increased membrane’s photocatalytic activity by 30–100%. More importantly, wastewater treatment by combining bentonite adsorption, ozonation, and photocatalytic membrane filtration has successfully improved permeate flux and performance stability, reduced fouling growth, and produced clean water. Therefore, the results of this study offers a new promising advanced wastewater treatment for Batik wastewater treatment to produce clean water.

Effects of pre-treatments on the filtration performance of ultra-low pressure gravity-driven membrane in treating the secondary effluent: Flux stabilization and removal improvement

Gravity-driven membrane (GDM) filtration is a promising technology for decentralized water and wastewater treatment due to its negligible energy consumption and low maintenance. This study investigated the flux development and permeate quality of the GDM process in treating the secondary effluent, as well as the influences of two practical pre-treatments, including GAC filter and microfiltration (MF), on its filtration performance. The results indicated that the GAC filter could significantly enhance the removal of organic contaminants (i.e., DOC, UV254, and fluorescent substances), with an average removal of 70 % for DOC and 80 % for UV254, respectively. Meanwhile, GAC/GDM systems exhibited a superior removal performance of manganese and sulfamethoxazole (SMX) for more than 95 % and 80 %, respectively. Furthermore, the optimized mixing ratio between GAC permeates and secondary effluent was 7:3 (GAC7:3) to reach a flux level close to the GDM control and achieve a superior permeate water quality than the other processes. The flux of GDM control could stabilize at the level of 5.47 ± 0.71 L m−2h−1 during long-term filtration. Unexpectedly, limited flux improvements were observed with the pre-treatments, and the stable flux of GAC/GDM and MF/GDM was close to or slightly lower than the GDM control. In GDM control, a rough, heterogeneous, and porous biocake layer was observed on the membrane surface. By contrast, the cake layer structures in the GDM system coupled with pre-treatments appeared denser, compact, and homogeneous, resulting in relatively lower stable flux relative to the GDM control. The economic assessment indicated that the optimized process of GAC7:3 showed a significant cost advantage in the small and medium-scale water reuse scenarios. These findings were beneficial to develop new energy-saving membrane-based technology for the reclamation of wastewater.

Dissecting the role of membrane defects with low-energy barrier on fouling development through A collision Attachment-Monte Carlo approach

Membrane defects with low energy-barrier characteristics are unavoidable in membrane fabrication. However, their influences on fouling have not been fully understood. This work systematically investigates the critical role of membrane defects on fouling development and characteristics by adopting a collision attachment-Monte Carlo approach. Simulations show that membrane defects influencing on fouling is highly governed by foulant-clean-membrane interaction (F-M) and foulant-fouled-membrane interaction (F–F). When F–F energy barrier (Ef) is above a critical value (Ec), the long-term stability of water flux is not affected by the presence of defects, thanks to high F–F repulsion preventing further particles deposition. At low Ef (<Ec) but high F-M energy barrier Em (≥Ec), there appears an extended metastable flux for defect-free membrane. Since the local defects serve as hotspots to accelerate fouling, increased coverage or lowered energy barrier of defects shortens or even vanishes metastable period. For both low Ef (<Ec) and Em (<Ec), severe fouling occurs at the beginning of filtration with/without defects as a result of the rapid fouling transition from F-M to F–F. Furthermore, membrane defects have less remarkable influences at higher initial flux where permeate drag plays a primary role. Our simulation provides important implications to membrane design and fouling mitigation.

Holographic perspectives on models of moduli stabilization in M-theory

Recent holographic analyses on IIA and IIB models of moduli stabilization have led to many interesting results. Here we extend this approach to M-Theory. We consider both flux-stabilized models and non-perturbative stabilization methods. We perform a holographic analysis to determine the spectrum of the assumed dual CFT3 to see its AdS/CFT implication. For the flux stabilization, which relies on a large complex Chern-Simons invariant, moduli have integer dimensions similar to the DGKT flux-stabilized model in type IIA. For the non-perturbative stabilization, the results are similar to racetrack models in type IIB.

Linking the long-term variability in global wave energy to swell climate and redefining suitable coasts for energy exploitation

The sustainability of wave energy linked to the intra- and inter-annual variability in wave climate is crucial in wave resource assessment. In this study, we quantify the dependency of stability of wave energy flux (power) on long-term variability of wind and wave climate to detect a relationship between them. We used six decades of re-analysis wind and simulated wave climate in the entire globe and using two 30-yearly periods, we showed that not only the previously suggested minimum period of 10 years for wave energy assessment appears to be insufficient for detecting the influence of climate variability, but also the selection period for wave energy assessment can lead to an over/underestimation of about 25% for wave power. In addition, we quantified the dependency of rates of change of wave power, wind speed and wave parameters and showed that the change in wave power is mainly a function of change in swell wave climate globally. Finally, we redefined the suitability of global hotspots for wave energy extraction using intra-annual fluctuation, long-term change, and the available wave power for the period of six decades. The results highlight the importance of climate variability in resource assessment, sustainability, and prioritizing the hotspots for future development.

Photocatalytic polysulfone membrane incorporated by ZnO-MnO2@SiO2 composite under UV light irradiation for the reliable treatment of natural rubber-laden wastewater

The effects of adding zinc oxide-manganese oxide @ silicon dioxide (ZnO-MnO2@SiO2) photocatalyst composite to polysulfone (PSf) membrane that was performed for natural rubber-laden wastewater (NRW) treatment are presented in this study. The sol–gel method was adopted to synthesize the photocatalyst composites, and the non-solvent induced phase separation (NIPS) technique was applied to synthesize the membranes. The PSf/ZnO-MnO2@SiO2 membrane has a smooth surface with a well-constructed finger-like structure and a fairly uniform dispersion of photocatalyst elementals on its surface, according to SEM and EDX mapping data. From AFM results, the addition of ZnO-MnO2@SiO2 photocatalyst resulted in a rougher surface image. In the FTIR spectrum of PSf/ZnO-MnO2@SiO2 membrane, many new polar functional groups such as Zn-O, Mn-O, and Si-O-Si were identified. The MnO2 doping in the composite successfully increased the photo-sensitivity and photocatalytic activity of the composite, implying that the bandgap energy was reduced from 3.10 eV to 2.65 eV, promoting photocatalytic improvement. The membrane porosity, hydrophilicity, water absorption ability, and mechanical strength are all enhanced with the addition of the ZnO-MnO2@SiO2 photocatalyst. Performing the PSf/ZnO-MnO2@SiO2 membrane under UV light irradiation significantly improved the flux stability, membrane recyclability, and antifouling properties that prevented the fouling formation and prolonged the usability of the membrane. In conclusion, the PSf/ZnO-MnO2@SiO2 membrane is determined to be the most promising UV light-driven photocatalytic membrane for successful NRW treatment based on all attributes and performance.