Unconfined compressive strength of loose sandy soils grouted with zeolite and cement

Cement production requires a lot of energy and is also one of the most important sources of carbon dioxide emissions. Consequently, the replacement of part of the cement with a more environmentally friendly material, such as zeolite, is of great importance. The present research involves the conducting of a series of laboratory tests on loose sand specimens ($D_r\approx 30\%$) grouted with cementitious materials (cement and zeolite) to investigate the effect of different parameters, such as the size of the sand particles, the ratio of water to cementitious materials (W/CM) and the replacement of a certain percentage of the cement in the grout with zeolite (Z), on the unconfined compressive strength (UCS) of the grouted sand specimens. The results indicate that for all the grout W/CM and sand grain sizes, when Z is increased from zero zeolite (Z₀), the UCS initially increases. Then, after reaching an optimal amount (Z₃₀), it decreases. Moreover, increasing both the size of the sand particles and the W/CM of the grout is seen to reduce the UCS of the grouted specimens. The UCS of the grouted sand specimens increases with the equilibrium of SiO₂ and Al₂O₃ with CaO elements in the grouting suspension. Finally, equations with a high performance are proposed to predict the UCS of sands grouted with zeolite-cement using a multiple regression model (MRM) and a group method of data handling (GMDH)-type neural network.     

Monitoring simple linear profiles in the presence of generalized autoregressive conditional heteroscedasticity

In this paper, monitoring of simple linear profiles is investigated in the presence of nonequality of variances or heteroscedasticity, ie, generalized autoregressive conditional heteroscedasticity. In this condition, using of the common methods regardless of the heteroscedasticity leads to the fault interpretations. We consider a simple linear profile and assume that there is a generalized autoregressive conditional heteroscedasticity (GARCH) (1,1) model within the profiles. Here, we particularly focus on Phase II monitoring of simple linear regression. We studied the generalized autoregressive conditional heteroscedasticity effect, briefly GARCH effect, on the average run length criterion. As the remedial measures, the weighted least squares method to estimate the regression parameters and the heteroscedasticity‐consistent approaches to estimate the covariance matrix of regression parameters, are used to extract the GARCH effect. Two control chart methods namely T² and exponentially weighted moving average 3 are discussed to monitor the simple linear profiles. Their performances are evaluated by using the average run length criterion. Finally, a real case from an industry field is studied.     

Crosstalk analysis of uniform and nonuniform lossy microstrip‐coupled transmission lines

In this article, an analytical method is presented to precisely estimate the crosstalk of uniform and nonuniform microstrip‐coupled transmission lines (TLs) in frequency domain using modified transmission matrix. The obtained expression is quantitatively related in terms of the geometrical parameters of the coupled lines. A straightforward procedure is presented to obtain a closed form formula to accurately determine the crosstalk of a microstrip‐coupled line. For a nonuniform structure, the TL is divided into a few series of uniform sections with a specific modified transmission matrix. The total modified transmission matrix is determined by multiplying the modified transmission matrix of different sections and then the crosstalk can be calculated using the total modified transmission matrix. Several structures are considered to confirm the validity of the presented method. It is shown that the obtained results are in a good agreement with those obtained by simulation and measurement.     

MHD natural convection in a nanofluid filled inclined enclosure with sinusoidal wall using CVFEM

Magnetohydrodynamic flow in a nanofluid filled inclined enclosure is investigated numerically using the Control Volume based Finite Element Method. The cold wall of cavity is assumed to mimic a sinusoidal profile with different dimensionless amplitude, and the fluid in the enclosure is a water-based nanofluid containing Cu nanoparticles. The effective thermal conductivity and viscosity of nanofluid are calculated using the Maxwell–Garnetts and Brinkman models, respectively. Numerical simulations were performed for different governing parameters namely the Hartmann number, Rayleigh number, nanoparticle volume fraction and inclination angle of enclosure. The results show that in presence of magnetic field, velocity field retarded, and hence, convection and Nusselt number decreases. At Ra = 10³, maximum value of enhancement for low Hartmann number is obtained at γ = 0°, but for higher values of Hartmann number, maximum values of E occurs at γ = 90°. Also, it can be found that for all values of Hartmann number, at Ra = 10⁴ and 10⁵, maximum value of E is obtained at γ = 60° and γ = 0°, respectively.     

Triaxial behavior of fiber-reinforced cemented sand

In this research, a series of laboratory tests have been performed to investigate the effects of cement and polypropylene (PP) fiber on the triaxial behavior of sand. The cement contents were 0 and 5% by weight of the dry sand. Fiber length and diameter were 18 and 0.023 mm, respectively, were added at 0 and 0.6% by weight of dry sand–cement. Triaxial compression tests were performed at confining pressures of 0.1, 0.25, 0.5, and 1 MPa. The results of the study indicate that the inclusion of PP fiber increases the shear strength and the peak axial strain. The elastic modulus of specimen decreased with increase in fiber content and increased with the increase in cement content. Moreover, the initial stiffness and peak strength increased by increasing cement content.     

Effect of a magnetic field on natural convection in an inclined half-annulus enclosure filled with Cu–water nanofluid using CVFEM

In this paper, the effect of a magnetic field on natural convection in a half-annulus enclosure with one wall under constant heat flux using control volume based finite element method. The fluid in the enclosure is a water-based nanofluid containing Cu nanoparticles. The effective thermal conductivity and viscosity of nanofluid are calculated using the Maxwell–Garnetts (MG) and Brinkman models, respectively. Numerical simulations were performed for different governing parameters namely the Hartmann number, Rayleigh number and inclination angle of enclosure. The results indicate that Hartmann number and the inclination angle of the enclosure can be control parameters at different Rayleigh number. In presence of magnetic field velocity field retarded and hence convection and Nusselt number decreases.     

Imaging conductive materials with high frequency electrical capacitance tomography

Electrical capacitance tomography (ECT) is known as an imaging technique for dielectric permittivity imaging. A novel ECT sensor model at a high excitation frequency is proposed to examine the capability of the ECT system to image both conductivity and permittivity contrasts. The proposed model uses a complex impedance forward model for the ECT system. This new model indicates that in higher excitation frequency both conductive and dielectric imaging may be feasible. Normally, capacitance tomography is designed for the measurements of imaginary part and resistance tomography is used to take the measurements of real part. The drawback of a typical capacitance tomography at a low excitation frequency, such as 200 kHz is that it cannot be used to measure the conductive phase of a conductive/dielectric mixed fluid, e.g. the gas/water flow. By increasing the excitation frequency, the capacitive impedance of the conductive material decreases and dielectric phenomena of the conductive fluid dominates so that it is possible to use capacitance tomography to characterise the dielectric/conductive flows. This paper presents a development of capacitance tomography with a high excitation frequency in measuring the gas/liquid mixture i.e. gas/water and gas/oil multiphase distributions. Both theoretical and experimental results are presented to verify this feasibility study.     

An integrated approach to determine the block layout,AGV flow path and the location of pick-up/delivery points in single-loop systems

Layout design and material handling system design are two of the major aspects of facility planning. Although both aspects directly influence each other, the classical approach to the layout design is carried out in two separate steps: in the first step the block layout, i.e. the location of the departments in the workshop, is constructed, and in the second step, the material handling system is designed. The separate optimisation of these two aspects of the problem leads to solutions that can be far from the global optimum. In this paper, we develop an integrated algorithm to design the facilities and material handling systems. We focus on single-loop AGV systems. The proposed algorithm determines the block layout, AGV single-loop flow path and pick-up delivery stations, simultaneously. The associated from–to chart and the area of departments are the principal inputs of the algorithm. The objective is minimising total material flow distance among all departments. The results of our computational experiments show the algorithm was coded using MATLAB 7.0, and that our integrated algorithm is more efficient in terms of both the objective function value and the runtime.     

Thermodynamic Analysis of Liquefied Natural Gas （LNG） Production Cycle in APCI Process

The appropriate production of liquefied natural gas(LNG)with least consuming energy and maximum efficiency is quite important.In this paper,LNG production cycle by means of APCI Process has been studied.Energy equilibrium equations and exergy equilibrium equations of each equipment in the APCI cycle were established.The equipments are described using rigorous thermodynamics and no significant simplification is assumed.Taken some operating parameters as key parameters,influences of these parameters on coefficient of performance(COP)and exergy efficiency of the cascading cycle were analyzed.The results indicate that COP and exergy efficiency will be improved with the increasing of the inlet pressure of MR(mixed refrigerant)compressors,the decreasing of the NG and MR after precooling process,outlet pressure of turbine,inlet temperature of MR compressor and NG temperature after cooling in main cryogenic heat exchanger(MCHE).The COP and exergy efficiency of the APCI cycle will be above 2% and 40%,respectively,after optimizing the key parameters.     

Improvement in the Cleaning Performance Towards Protein Soils in Laundry Detergents by Protease Immobilization on the Silica Nanoparticles

This work aimed to understand the effect of protease immobilization on silica nanoparticles and how such immobilization affects protease performance as catalysis for enhancing the removal of protein soils. Detergent products contain many components that may affect the free enzyme activity and stability. Various factors such as temperature, pH and humidity are know to affect enzyme activity and cleaning efficiency. Therefore, the effect of enzyme immobilization on the removal of protein based soil was investigated on cotton fabrics as the model soil. The effect of temperature and humidity on the stability of free and immobilized enzyme was compared. It was found that the immobilized enzyme increased cleaning efficiency toward protein soil removal on cotton fabrics, whereas the free enzyme imposed a small effect on the enzymatic activity towards the same soil substrates. In addition, the stability of the immobilized enzyme against temperature and humidity was much higher than its corresponding value by free enzyme.