Solution Curves Research Articles

INTERRELATION OF SERUM ALBUMIN CONFORMATIONAL AND PHASE STATES IN SALT SOLUTIONS AS STUDIED BY EPR SPIN LABELING

The use of serum albumins (SA) in model systems in the study of the biological activity of chemical compounds and nanomaterials, as well as the physicochemical properties, in particular, phase properties of biological fluids, including the nucleoplasm and cytoplasm of living cells, requires a deeper understanding of the relationship of conformational (structural-dynamic) states of protein molecules with phase states of protein dispersions in a wide range of temperatures and compositions. The joint plotting and analysis of the protein stability curve and phase diagrams of protein solutions commonly used in the study of this relationship are significantly complicated by this protein’s elevated tendency to aggregate. In this paper, an experimental-theoretical approach, based on the application of the electron spin resonance (ESR) of spin labels (maleimido-TEMPO and dichlortriasine-TEMPO spin labels) covalently bound to the protein and sensitive to changes in both the structural-dynamic state of protein molecules and the phase state of protein dispersions, is proposed for studying this relationship. Data on the mobility characteristics of the spin labels (correlation times, state functions, equilibrium constants), indicating the state of intra- and intermolecular interactions of SA molecules, are presented. Transitions in temperature dependences of these characteristics on the temperature and concentration of NaCl, CaCl2, (NH4)2SO4, sucrose, polyethylene glycol, and heavy water have been shown to reflect the interconversions of protein conformers and their aggregates as well as liquid-liquid phase transitions, including those of a reentrant type. Based on the results, a phase diagram of the SA dispersion describing liquid-liquid phase transitions in the temperature range of cold and thermal denaturation and taking into account the role of native protein conformers, their aggregates and transitions between them in the physiological interval has been proposed.

In-Vitro Degradation of Hollow Silica Reinforced Magnesium Syntactic Foams in Different Simulated Body Fluids for Biomedical Applications

This article reports the mechanical and biocorrosion behaviour of hollow silica nanosphere (SiO2) reinforced (0.5–2 vol.%) magnesium (Mg) syntactic foams. Room temperature tensile properties’ characterization suggests that the increased addition of hollow silica nanospheres resulted in a progressive increase in tensile yield strength (TYS) and ultimate tensile strength (UTS) with Mg-2 vol.% SiO2 exhibiting a maximum TYS of 167 MPa and a UTS of 217 MPa. The degradation behaviour of the developed Mg-SiO2 syntactic foams in four different simulated body fluids (SBFs): artificial blood plasma solution (ABPS), phosphate-buffered saline solution (PBS), artificial saliva solution (ASS) and Hanks’ balanced saline solution (HBSS) was investigated by using potentiodynamic polarization studies. Results indicate that corrosion resistance of the Mg-SiO2 syntactic foam decreases with increasing chloride ion concentration of the SBF. Mg-1.0 vol.% SiO2 displayed the best corrosion response and its corrosion susceptibility pertaining to corrosion rate and polarisation curves in different SBF solutions can be ranked in the following order: ABPS > PBS > HBSS > ASS. The surface microstructure demonstrated the presence of a better passivated layer on the syntactic foams compared to pure Mg. The observed increase in corrosion resistance is correlated with intrinsic changes in microstructure due to the presence of hollow silica nanospheres. Further, the effect of corrosive environment on the degradation behaviour of Mg has been elucidated.

1-Butyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquid As an Electrolyte for Electrochemical Reduction of Nitrous Oxide.

Nitrous oxide (N2O), of which global warming potential is 310 times of CO2, is a powerful greenhouse gas [1]. The concentration of N2O has increased steadily from various agricultural and industrial activities such as cultivating crops in low-pH soil and manufacturing semiconductor devices [2,3]. Therefore, the importance of studying N2O reduction is emphasized. Thermal decomposition methods focusing on thermal catalyst have been reported, but there are limits such as process temperature and low efficiency [4,5]. Electrochemical reduction of N2O can be an attractive method since it is conducted at low temperatures and has low energy consumption. However, in aqueous solutions, the electrochemical reduction of N2O inevitably accompanies hydrogen evolution reaction (HER), which is the main side reaction. There were many trials to reduce HER through metal and metal oxide catalysts, but they also had limits in terms of efficiency and high cost of noble metal materials [6-9]. Ionic liquids are promising electrolytes in gas reduction field replacing water because they can avoid hydrogen evolution and enhance the solubility of gaseous reactants. Some imidazolium-based ionic liquids were adopted to electrochemical reduction of CO2 because of their favorable properties such as wide electrochemical potential window and high CO2 dissolution capacity [10,11]. Cations of ionic liquids are known to accept oxygen from CO2, and then return to initial state at counter electrode emitting oxygen [12]. According to the same principle, ionic liquids may also be suitable for the electrochemical reduction of N2O.In this study, an ionic liquid/organic solvent mixture was adopted as an electrolyte for the electrochemical reduction of N2O. The ionic liquid and organic solvent used for electrolyte were 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and propylene carbonate (PC), respectively. The use of [BMIM][BF4] in place of aqueous solutions could improve the solubility of N2O and also avoid the hydrogen evolution reaction, which is the main side reaction in an aqueous solution.Herein we observed the difference of LSV curves in aqueous solution and [BMIM][BF4]. Hydrogen evolution reaction was excluded, but the low current density was obtained in [BMIM][BF4]. The low electrical conductivity and high viscosity of [BMIM][BF4], the main disadvantages in the context of electrochemical reactions, were compensated on introducing PC. We measured the viscosity and electrical conductivity in various [BMIM][BF4]/PC composition, and the composition of the [BMIM][BF4]/PC was optimized considering both the electrical conductivity and N2O stability in the solution. The current and faradaic efficiency could be evaluated during chronoamperometry in aqueous solution and [BMIM][BF4]/PC. For the optimized [BMIM][BF4]/PC, high current efficiency and faradaic efficiency (>90%) were achieved for N2O reduction to N2.Figure captionsFigure 1. LSV curves for Cu electrode in (a) 0.3 M K2SO4 aqueous solution and (b) [BMIM][BF4]. The scan rate was 50 mV s-1.Figure 2. (a) Viscosity (black line) and conductivity (blue line) changes for [BMIM][BF4]/PC according to [BMIM][BF4] content (b) Current efficiency–time curves recorded at –1.3 V vs. SCE in 0.3 M K2SO4 aqueous solution (blue line) and at –2.27 V vs. Fc/Fc+ in 75 vol% [BMIM][BF4] (red line).

Fractional modeling of temperature dynamics of a building with singular kernels

Abstract In the current study, the temperature dynamics of a building are proposed by means of some non-local singular fractional-order operators. In order to examine this model which has a crucial place in daily life, we utilize the Laplace transform. Accordingly, new analytical solutions including one, two, or three parameters are displayed to better control the non-renewable resources. One of the most remarkable features making the aforementioned model important is that it has different non-integer parameters α , ρ , and γ , which enable us to approach maximum energy efficiency for buildings. Moreover, simulation analysis is carried out to observe the mobility of the solution curve in line with our objective.

Morphological, Chemical, and Biological Investigation of Ionic Substituted, Pulse Current Deposited Calcium Phosphate Coatings.

Ionic substituted calcium phosphate coatings (iCP) have been prepared by the electrochemical pulse current deposition technique with an alternate pulse on and off time of 5 ms onto a titanium alloy substrate. The elemental distribution and morphology of the deposited layers have been extensively studied by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). The crystallinity and phase structure of iCPs have been investigated by X-ray diffraction (XRD). The corrosion characteristics and biodegradability of coatings have been determined by electrochemical measurements, recording potentiodynamic curves in a physiological solution over a long-term immersion period. The cell viability tests confirmed that the iCP coating was biocompatible, while the corrosion tests proved its biodegradable characteristic. In our paper, we compare the morphological, chemical, and biological characteristics of silver and zinc substituted calcium phosphate layers deposited by the electrochemical method.

Existence, uniqueness and an ODE approach to the L1-Karcher mean

We extend the domain of the Karcher mean Λ of positive operators on a Hilbert space to L1-Borel probability measures on the cone of positive operators equipped with the Thompson part metric. We establish existence and uniqueness of Λ as the solution of the Karcher equation and develop a nonlinear ODE theory for the relative operator entropy in the spirit of Crandall-Liggett, such that the solutions of the Karcher equation are stationary solutions of the ODE, and all generated solution curves enjoy the exponential contraction estimate. This is possible despite the facts that the Thompson metric is non-Euclidean, non-differentiable, non-commutative as a metric space as well as non-separable, and the positive cone is non-locally compact as a manifold. As further applications of the ODE approach, we prove the norm convergence conjecture of the power means of positive operators to the Karcher mean, and a Trotter-Kato product formula for the nonlinear semigroups explicitly expressed by compositions of two-variable geometric means. This can be regarded as a nonlinear continuous-time version of the law of large numbers.

Analytical calculation of deformations of a truss for a long span covering

Introduction. The method of induction based on the number of panels is employed to derive formulas designated for deflection of a square in plan hinged rod structure, which has supports on its sides and which consists of individual pyramidal rod elements. The truss is statically determinable and symmetrical. Some features of the solution are identified on the curves constructed according to derived formulas.
 Materials and methods. The analysis of forces arising in the rods of the covering is performed symbolically using the method of joint isolation and operators of the Maple symbolic math engine. The deflection in the centre of the covering is found by the Maxwell–Mohr’s formula. The rigidity of truss rods is assumed to be the same. The analysis of a sequence of analytical calculations of trusses, having different numbers of panels, is employed to identify coefficients, designated for deflection and reaction at the supports, in the final design formula. The induction method is employed for this purpose. Common members of sequences of coefficients are derived from the solution of linear recurrence equations made using Maple operators.
 Results. Solutions, obtained for three types of loads, are polynomial in terms of the number of panels. To illustrate the solutions and their qualitative analysis, curves describing the dependence of deflection on the number of panels are made. The author identified the quadratic asymptotics of the solution with respect to the number of panels. The quadratic asymptotics is linear in height.
 Conclusions. Formulas are obtained for calculating deflection and reactions of covering supports having an arbitrary number of panels and dimensions if exposed to three types of loads. The presence of extremum points on solution curves is shown. The dependences, identified by the author, are designated both for evaluating the accuracy of numerical solutions and for solving problems of structural optimization in terms of rigidity.

Multi-Objective Optimal Reactive Power Dispatch using Levy Interior Search Algorithm

In planning and operation processes of power systems, the most critical and outstanding problem is the optimal scheduling of reactive power resources. The current research study considered real power loss as well as the deviation of voltage magnitude as objective functions since these two play important roles in a power system’s operations and control. Due to the above-mentioned considerations, bi-objective optimization takes a form here. In the recent times, lot of meta-heuristic optimization techniques was implemented to elucidate ORPD problem. One such recently advanced algorithm named Interior Search Algorithm is utilized to find a solution for challenges in power system. It is observed that it is not producing accurate solution and convergence characteristic curve is also not smooth. In order to enhance the searching ability of ISA a new method called Levy Interior Search Algorithm (LISA) was proposed in this paper. In this two different strategies of LISA were proposed. In order to validate the proposed algorithm, LISA is implemented on five various standard test systems comprising IEEE 30-bus, IEEE 57-bus, IEEE 118-bus, IEEE 300-bus and IEEE 354-bus test systems. To conclude, application results of LISA are compared with the results of other optimization techniques reported in literature. The comparison reveals that the LISA Strategy-II outperformed all other optimization techniques in terms of robustness, accuracy and convergence speed.

Materials analysis applying thermodynamic (MAAT) software: A friendly and free tool to analyze the formation of solid solutions, amorphous phases and intermetallic compounds

Experimental thermodynamic measurements in multicomponent systems exhibit high complexity. Theoretical calculations by extrapolation of constitutive binary systems are an excellent tool to estimate the thermodynamic properties in ternary or quaternary systems. In this context, the Miedema and Bakker semi-empirical models are good to estimate the enthalpy of mixing or formation. This work presents a new software, MAAT (Materials Analysis Applying Thermodynamics), designed to calculate selected thermodynamic properties of binary and ternary systems. The MAAT is a free software that can be download from www.rpm.usm.cl. The MAAT software is a platform, written in MATLAB, which runs in 32/64 bits Windows systems. The main characteristics of the software are: i) calculation and plotting Gibbs free energy of mixing curves of random solid solutions, amorphous and intermetallic compounds, ii) calculation and plotting the activity of components in solid solutions, and iii) analysis of the effect of additional terms over the Gibbs free energy of mixing of random solid solutions, such as centrifugal field, grain size and dislocations. In this work, the thermodynamic calculations performed with MAAT are compared with experimental data in four cases: formation of solid solution (Cu-Mo-Cr system), formation of amorphous phase (Ti-Ta-Sn system), formation of intermetallic compound (Cu-Nb-Co system) and effect of centrifugal field on formation of solid solution (Cu-Cr system). For all systems analyzed, the calculations made using MAAT gave results that are comparable with experimental data. Program summaryProgram title: MAATCPC Library link to program files: https://doi.org/10.17632/56wydw5wf5.1Developer’s repository link: www.rpm.usm.clLicensing provisions: Creative Commons Zero (CC0)Programming language: MATLABNature of problem: Although there is a variety of codes and graphic interfaces to compute the Gibbs free energy of binary and ternary systems, most of them have strong restrictions, such as the knowledge of specific programming languages, complex routines of computation, closed source codes, or are paid softwares/databases.Solution method: MAAT is an user-friendly free software written in MATLAB that computes the Gibbs free energy of binary and ternary systems, applied to solid solutions, amorphous structures and intermetallic compounds, based on Miedema’s model for the calculation of the enthalpy of formation. The software integrates by default the required data of 58 elements to compute the thermodynamical terms.Additional comments including restrictions and unusual features: MAAT allows users to compute the effect of additional energy sources – grain size effect, dislocation effect and centrifugal field effect – in order to study how these affect the Gibbs free energy of a solid solution.All the parameters of the database have been calculated at 298 K and the input temperature is exclusively considered for the calculation of the entropic term. It is recommended to do calculations at or near this temperature.

Numerical Treatment of Time-Fractional Klein–Gordon Equation Using Redefined Extended Cubic B-Spline Functions

In this work, we have developed a numerical algorithm based on redefined extended cubic B-spline functions to explore the approximate solution for time fractional Klein--Gorden equation. The presented technique engages finite difference formulation for discretizing the Caputo time fractional derivative of order $\alpha \in (1,2]$ and redefined extended cubic B-spline functions to interpolate the solution curve along spatial grid. A stability analysis of the scheme is set up to affirm that the errors do not amplify during the execution of numerical procedure. The derivation of uniform convergence reveals that the scheme is $O(h^{2}+\Delta t^{2-\alpha})$ accurate. Some computational experiments are carried out to verify the theoretical considerations. Numerical results are compared with the existing techniques on the topic and it is concluded that the present scheme returns superior outcomes.

KCC Analysis of a One-Dimensional System During Catastrophic Shift of the Hill Function: Douglas Tensor in the Nonequilibrium Region

This paper considers the stability of a one-dimensional system during a catastrophic shift described by the Hill function. Because the shifting process goes through a nonequilibrium region, we applied the theory of Kosambi, Cartan, and Chern (KCC) to analyze the stability of this region based on the differential geometrical invariants of the system. Our results show that the Douglas tensor, one of the invariants in the KCC theory, affects the robustness of the trajectory during a catastrophic shift. In this analysis, the forward and backward shifts can have different Jacobi stability structures in the nonequilibrium region. Moreover, the bifurcation curve of the catastrophic shift can be interpreted geometrically, as the solution curve where the nonlinear connection and the deviation curvature become zero. KCC analysis also shows that even if the catastrophic pattern itself is similar, the stability structure in the nonequilibrium region is different in some cases, from the viewpoint of the Douglas tensor.

The Effect of Nickel on the Microstructure, Mechanical Properties and Corrosion Properties of Niobium-Vanadium Microalloyed Powder Metallurgy Steels.

In this study, the effects of adding Ni in different ratios to Fe-matrix material containing C-Nb-V produced by powder metallurgy on microstructure, tensile strength, hardness and corrosion behaviors were investigated. Fe-C and Fe-C-Nb-V powders containing 5%, 10%, 13%, 15%, 20%, 30% and 40% nickel were pressed at 700 MPa and then sintered in an Ar atmosphere at 1400 °C. Microstructures of the samples were characterized with optical microscope, scanning electron microscope (SEM) and XRD. Corrosion behaviors were investigated by obtaining Tafel curves in an aqueous solution containing 3.5% NaCl. Mechanical properties were determined by hardness and tensile testing. While Fe-C alloy and Fe-C-Nb-V microalloyed steel without Ni typically have a ferrite-pearlite microstructure, the austenite phase has been observed in the microstructures of the alloys with 10% nickel and further. Yield and tensile strength increased with nickel content and reached the highest strength values with 13% Ni content. The addition of more nickel led to decrease the strength. Analysis of Tafel curves showed that corrosion resistance of alloys increased with increasing nickel concentration.

Can Halophilic and Psychrophilic Microorganisms Modify the Freezing/Melting Curve of Cold Salty Solutions? Implications for Mars Habitability.

We present the hypothesis that microorganisms can change the freezing/melting curve of cold salty solutions by protein expression, as it is known that proteins can affect the liquid-to-ice transition, an ability that could be of ecological advantage for organisms on Earth and on Mars. We tested our hypothesis by identifying a suitable candidate, the well-known psycrophile and halotolerant bacteria Rhodococcus sp. JG3, and analyzing its response in culture conditions that included specific hygroscopic salts relevant to Mars—that is, highly concentrated magnesium perchlorate solutions of 20 wt % and 50 wt % Mg(ClO4)2 at both end members of the eutectic concentration (44 wt %)—and subfreezing temperatures (263 K and 253 K). Using a combination of techniques of molecular microbiology and aqueous geochemistry, we evaluated the potential roles of proteins over- or underexpressed as important players in different mechanisms for the adaptability of life to cold environments. We recorded the changes observed by micro-differential scanning calorimetry. Unfortunately, Rhodococcus sp. JG3 did not show our hypothesized effect on the melting characteristics of cold Mg-perchlorate solutions. However, the question remains as to whether our novel hypothesis that halophilic/psychrophilic bacteria or archaea can alter the freezing/melting curve of salt solutions could be validated. The null result obtained after analyzing just one case lays the foundation to continue the search for proteins produced by microorganisms that thrive in very cold, high-saline solutions, which would involve testing different microorganisms with different salt components. The immediate implications for the habitability of Mars are discussed.

The spectral curve method for the Kaup-Newell hierarchy

In nonlinear optics, ones often use models which associated with various variants of the nonlinear Schrödinger equation (NLSE): scalar NLSE, vector NLSE, derivative NLSE, etc. These equations are the first in their hierarchies: Ablowitz-Kaup-Newell-Segur, vector NLSE, Kaup-Newell, Gerdjikov-Ivanov, and Chen-Lie-Lui. A typical tool for analyzing the problem of propagation of electromagnetic nonlinear waves is the direct and inverse nonlinear Fourier transform. For recovering a periodic nonlinear signal one can use spectral curves. In this paper, we use the example of the Kaup-Newell hierarchy to show the possibilities of the spectral curve method. Using this method, one can find Lax pairs, integrable nonlinear equations, integrals, and spectral curves of solutions for any other hierarchies. The simplest examples of using this method are given.

(Solid + liquid) phase equilibria in the quaternary systems LiCl–Li2SO4–MgCl2–MgSO4–H2O and KCl–K2SO4–MgCl2–MgSO4–H2O at 288.15 K

The experimental solubility of LiCl–Li2SO4–MgCl2–MgSO4–H2O and KCl–K2SO4–MgCl2–MgSO4–H2O systems was measured at 288.15 K. The corresponding stable phase diagrams and water content diagrams were plotted by experimental results. Double salt was formed in both two systems. There are six phase fields, nine univariant solution curves and four invariant points in the phase diagram of LiCl–Li2SO4–MgCl2–MgSO4–H2O system. And the diagram of another system has seven invariant points and eight crystallization regions. By using multiple linear regression method, parameter ΨLi,Cl,SO4 and the solubility equilibrium constants of double salt KCl·MgSO4·3H2O were obtained by solubility data fitting at 288.15 K. The equilibrium solubility of salts in above systems at the same temperature was predicted with Pitzer's electrolyte solution model and mathematical calculation software. The results indicate that the predicted data are in correspondence with experiments.

Monolayer Quantum-Dot Based Light-Sensor by a Photo-Electrochemical Mechanism.

Monolayer nanocrystal-based light sensors with cadmium-selenium thin film electrodes have been investigated using electrochemical cyclic voltammetry tests. An indium tin oxide electrode system, with a monolayer of homogeneously deposited cadmium-selenium quantum dots was proven to work as a photo-sensor via an electrochemical cell mechanism; it was possible to tune current densities under light illumination. Electrochemical tests on a quantum dot capacitor, using different sized (red, yellow and green) cadmium-selenium quantum dots on indium tin oxide substrates, showed typical capacitive behavior of cyclic voltammetry curves in 2M H2SO4 aqueous solutions. This arrangement provides a beneficial effect in, both, charge separation and light sensory characteristics. Importantly, the photocurrent density depended on quantum yield rendering tunable photo-sensing properties.

Hydrogen reaction analysis in aqueous solutions containing H2S/CO2 at different pressures

The hydrogen evolution reaction (HER) in H2S and H2S/CO2 solutions at different pressures was studied using platinum and stainless steel as working electrodes, with polarization curves and electrohydrodynamic impedance. When Pt was the working electrode, the polarization curves in H2S solutions without CO2 presentedonly one current plateau, while two plateaus were seen when a mixture of H2S/CO2 was used. However, when steel was the working electrode, two plateaus always existed even in the presence of H2S without CO2. HER was interpreted by another source of H2 coming from the H2S reaction coupled to the classical direct reduction of H+.

The 4th Industrial Revolution and Business Education Reform

Based on recent research works, important concepts on the finite element analysis of shell structures and the relations among them are presented in this paper. We review the basic shell mathematical model, which is the underlying mathematical model of the continuum mechanics based shell finite elements. The asymptotic theory of shell structures then is reviewed and we present how to evaluate the asymptotic behavior in finite element solutions. S-norm is introduced as an error measure of finite element solutions and we show "locking" in the convergence curves of shell finite element solutions. We discuss the concept of "uniform optimal convergence" in finite element analysis of shells. We finally summarize requirements on ideal shell finite elements and propose how to perform benchmark tests of shell finite elements.

Hydrometallurgical recovery of zinc from industrial hot dipping top ash

Abstract Top ash from hot-dip galvanizing plant was investigated as a source of secondary zinc to be returned to galvanizing bath. The waste material contained 63% Zn as metallic, oxide and hydroxychloride phases. It was leached in H2SO4 solutions (20% and 25%) at various bath loadings (100−300 g/L). Leaching behaviors of zinc, manganese, iron and chloride ions were investigated. A few strategies of iron elimination from leaching liquors were examined. Flocculant addition was harmful for subsequent filtration of iron precipitates due to increased viscosity of solution, while a combination of zinc oxide and calcium carbonate for rising pH resulted in the formation of dense suspension unenforceable to separate from zinc sulphate solution. Zinc electrowinning was carried out at different pH (from −0.5 to 2.8) using a range of current densities (3−10 A/dm2). Optimal conditions for pure metal recovery were: leaching in 20% H2SO4 solution at zinc ash content 100−150 g/L, Fe2O3·xH2O precipitation using H2O2 and CaCO3, zinc electrowinning at pH of 0.1−1.0 at 3−6 A/dm2. Correlations between pH and free H2SO4 concentration in electrolyte solutions were also discussed. pH−acid concentration dependence for zinc electrolyte was between experimental and calculated curves for pure H2SO4 solutions, while the curve was shifted towards lower pH if ferric ions were in the solution.

Intelligent cloud workflow management and scheduling method for big data applications

With the application and comprehensive development of big data technology, the need for effective research on cloud workflow management and scheduling is becoming increasingly urgent. However, there are currently suitable methods for effective analysis. To determine how to effectively manage and schedule smart cloud workflows, this article studies big data from various aspects and draws the following conclusions: Compared with the original JStorm system, the response time is shortened by a maximum of 58.26% and an average of 23.18%, CPU resource utilization is increased by a maximum of 17.96% and an average of 11.39%, and memory utilization increased by a maximum of 88.7% and an average of 71.16%. In terms of optimizing the dynamic combination of web services, the overall performance of both the MOACO and CCA algorithms is better than that of the GA algorithm, and the average performance of the MOACO algorithm is better than that of the CCA algorithm. This paper also proposes a cloud workflow scheduling strategy based on an intelligent algorithm and realizes the two-tier scheduling of cloud workflow tasks by adjusting the combination strategy for cloud service resources. We have studied three representative intelligent algorithms (ACO, PSO and GA) and improved them for scheduling optimization. It can be clearly seen that in the same scenario, the optimal values of the different algorithms vary greatly for different test cases. However, the optimal solution curve is substantially consistent with the trend of the mean curve.