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This study intends to determine the behavior of glass laminate aluminum-reinforced epoxy (GLARE) and glass fiber-reinforced polymer (GFRP) composites under a low-velocity impact test. Experimental tests and numerical simulations are considered for this investigation. All samples are made by the hand lay-up method. Moreover, specimens are produced with a 7075-T6 aluminium sheet with a 0.5 mm thickness, resin 3001, and E-glass fiber. The drop weight test performs the low-velocity impact at 6.7 J and 10 J impact energy levels and the heights of 1.0 m and 1.5 m. Numerical simulation is also conducted by ANSYS software to compare the results obtained by the experimental tests. Generally, results show that maximum deflections of the GLARE samples are significantly lower as compared to GFRP ones by 87% and 83.5% for 1.0 m and 1.5 m drop heights, respectively. Experimental results demonstrate that although aluminum sheets prevent damage to the fibers in GFRP, delamination and fractures between layers are observed in GFRP samples. An appropriate agreement is also obtained between the FE results and experimental data.

Although research has shown a considerable influence of the pre-cracking phenomenon on steel-congested concrete members, only normal concrete (NC) has been considered in the literature. The intention in this paper is thus to study the effect of the pre-cracking phenomenon on the bond response of pre-cracked NC with different slump flow values and self-consolidating concrete (SCC). Initial crack widths ranging from 0.0 to 0.5 mm are studied. Results show that initial crack widths larger than 0.10 mm have a significant influence on bond properties, such that reduction factors greater than 30% and 50% are obtained for the maximum bond strength of concrete specimens exposed to initial crack widths of 0.2 mm and 0.4 mm, respectively. Results show that concrete mixtures with higher workability are less sensitive to the pre-cracking phenomenon as compared to NC mixtures. The average bond stress of steel rebar in the pre-cracked SCC is found to be similar to that of the NC with a slump flow of 200 mm, which is considerably better than for NC with a slump flow of 97 mm. Moreover, results show that 65.8, 80.6, 88.5 and 93.1% fracture energy reductions are obtained for crack widths of 0.20, 0.30, 0.40 and 0.50 mm, respectively, as compared to the small crack width of 0.15 mm.

The negative environmental impacts of Portland cement as a binder in the construction industry have created a growing impetus to develop sustainable alternative binders. Various types of clay have been considered as potential cement replacements. The impact of clays as cement replacement depends on the dosage and treatment methods. This paper presents a comprehensive review to determine the effects of different types of clay on the fresh and hardened properties of concrete mixtures by analyzing the experimental database reported by the literature, including raw, calcined, modified, nano, and organo. This study intends to show the process of optimizing the use of clay in concrete, the reason behind converting raw clay to modified types, and research gaps through a comparison study between different types of clays. The present review study shows that clay-based concrete mixtures have higher thixotropy and yield stress values, improving shape stability. This results in lower early-age shrinkage of the concrete. However, the high floc strength of clay-based concrete causes a reduction in flowability. Treatment methods of raw clay, such as calcination and nano-sized clay particles, improve concrete compressive strength. General results of the previous studies highlight that all types of clay investigated positively affect the resistance of concrete to environmental attack.

The disposal of personal protective equipment (PPE) is a main concern of researchers. In recent years, the COVID-19 pandemic made this issue worse, so the production and use of large quantities of disposable gloves in recent years and the lack of a suitable solution for the disposal of these recycled materials are some of the consequences of this pandemic. To address this issue, the present study performed a comprehensive experimental program to determine the possibility of using recycled latex and vinyl gloves as recycled fibers within extrusion-based 3D printing concrete. Moreover, a graphene oxide (GO) nanomaterial was also used to compensate for some undesired properties of mixtures. Flow table, buildability, and mechanical tests were performed in this study. Results show that the synergic effect of recycled fibers and GO significantly improved the 3D printing characteristics of mortar. Although very promising results were obtained in this study, findings show that using a high content of recycled fibers reduces the concrete compressive strength. However, the addition of GO significantly compensates for this reduction.

The Savonius wind turbine is one of the most well-known vertical axis wind turbines with insensitivity to wind direction, flow turbulence, and high torque generation. These turbines can extract up to 20% of the energy from the wind. This study numerically analyzes the performance of a modified Savonius wind turbine equipped with secondary blades and slots. The k-ε standard method is used to simulate the turbulence flow around the turbine, and the simulation is performed using the ANSYS FLUENT 18.2 commercial code. The effects of distance between the main blade and the secondary blade, position of the secondary blade, the width of the main blade’s slot, and the profile of the secondary blade on the produced torque are studied and analyzed. The simulation is performed at four wind velocities: 3, 4, 5, and 6 m/s. The results showed that the output torque at the secondary blade angular position β = 130 is higher than other angles. Furthermore, by increasing the radius of the additional blade from R = 25 to 43 mm, the torque is improved, and the area below the output torque curve is increased. Moreover, the results showed that creating a slot on the main blade equipped with a secondary blade has a significant impact on the produced torque; however, the geometrical parameters of the proposed rotors should be adjusted accurately to find the best case in terms of the produced torque.

In this work, the performance of the Savonius vertical axis wind turbine with secondary blades was investigated numerically. The impacts of two geometric parameters of the secondary blades, including the height of secondary blades (h) and the distance between the main and the secondary blades (b) on the output torque were analyzed. Numerical simulations were performed by a commercial CFD code, ANSYS FLUENT 18.2. Numerical results show that employing secondary blades has a constructive impact on the output torque compared to the case without secondary blades. Moreover, the studied geometric parameters of the secondary blades have a significant impoact on the performance of the proposed turbine. It can be seen that by increasing the height of secondary blades, the angular position of the maximum torque is shifted. At b = 2.5 mm, the difference between the models is more comparable. Models h = 6 and 12 mm have the highest output torque, although with a slight difference between them. Model h = 12 mm has the highest output torque. At b = 7.5 mm, the difference between the models is more comparable than b = 2.5 mm. Model h = 12 mm has the highest output torque and models h = 3 and 6 mm are in the next levels. Obtained results in the second section demonstrate that by growing the distance between the secondary and the main blades, in the case of h = 3 mm, the produced torque declines. Furthermore, by increasing the distance between the secondary and the main blades from b = 0 mm to b = 2.5 mm and b = 7.5 mm, the amount of torque produced decreases by 17.33 and 26.66%, respectively. Moreover, by augmenting the distance between the secondary and main blades from b = 2.5 mm to b = 7.5 mm (200% growth), the produced torque decreases by 11.3%.

In this work, the impact of cone diameters on the flow field and separation efficiency in a cyclone separator is examined numerically employing Reynolds Stress Model for eight various geometries of cyclone separators. The motion of solid particle in the flow field is modelled utilizing the Eulerian-Lagrangian method. Three-dimensional simulation of the air flow with solid particles in the cyclone is carried out by a commercial computational fluid dynamics software, ANSYS Fluent 18.2. The outcomes depict that by augmenting the small cone diameter, the maximum tangential velocity, static pressure, and collection efficiency decrease, however, cut-off diameter rises. Moreover, the axial velocity has steady trend throughout the cyclone. In addition, according to the obtained results, increasing the large cone diameter causes an increase in the tangential velocity and static pressure and improves the collection efficiency. While, the higher large cone diameter, the lower cut-off diameter. Growing the cyclone’s cone small diameter leads to a decrease in the collection efficiency. At a constant particle diameter, four microns, as the cone small diameter ratio augments by 150%, collection efficiency declines by about 10.42%. Augmentation the cyclone’s cone small diameter causes an increase in the cutoff diameter. By increasing the cone small diameter by about 150%, the cut-off diameter value increases by about 75%. Furthermore, the collection efficiency rises by growing the cyclone’s cone large diameter. At a constant particle diameter, four microns, as the cone large diameter augments by 50%, the collection efficiency increases by about 18.75%. Also, in all considered cone large diameter, the collection efficiency increases as the particle diameter rises. The cut-off diameter decreases by growing the cyclone’s cone large diameter. By augmenting the cone large diameter by about 50%, the cut-off diameter value declines by about 57.69%.

Self-compacting concrete (SCC) is commonly used when compaction is challenging, requiring special attention towards curing. Conventional curing techniques often fail in practice. Water evaporation is often reduced even when precise control measures are taken, but surface water on vertical structure elements remains a problem. To address these challenges, this study intends to determine the possibility of achieving self-curing self-compacting concrete (SCSCC). As curing agent plays a significant role in producing SCSCC, this study concentrates on assessing the impact of polyethylene glycol (PEG) addition at different rates of 0.5%, 1%, 1.5%, and 2% on the fresh, hardened, durability characteristics. Moreover, to improve the sustainability properties of SCSCC, manufactured sand (M-sand) obtained from rock crushing operations is used as a replacement for river sand. Generally, results indicate that using superplasticizer and M-sand is sufficient for achieving the required flowability for SCC mixtures without using specific fillers, promptly controlling bleeding and segregation, and maintaining the necessary compressive strength at all ages. The hardened properties of SCSCC were improved by increasing PEG content up to 1.5% with an optimal range of 0.5% superplasticizer. Also, results show that self-cured specimen cured with PEG has greater acid resistance as compared to the conventionally cured one.

This study intends to determine the effect of fiber type and aggregate content on hardened and durability properties of self-consolidating concrete. Steel, glass, and steel/glass hybrid fibers are tested in the present experimental program. Additionally, the effect of aggregate content is considered by using different packing factors and sand-to-all aggregate ratios. Moreover, normal and high strength concrete grades are prepared. Compressive, splitting tensile, flexural, and impact tests are conducted for measuring hardened properties of concrete mixtures. Absorption, desorption, acid attack, resistivity, potential, and chloride diffusion are also durability tests carried out in the present study. Results show that 1.0% and 0.05% are the optimal dosage of steel and glass fibers respectively. Results show that packing factor plays a major role in mechanical characteristics of fiber-reinforced self-consolidating concretes so that an optimal value of 1.12 and 1.14 is obtained for mechanical properties. Also, experimental results reveal that for 1.12 packing factor, the sand-to-all aggregate ratio needs to be equal to the value of 0.50, while 0.57 is achieved as an optimum value for packing factor of 1.14. Overall, results show that hybrid-reinforced self-consolidating concrete is promising for mechanical and durability performance as compared to other mixtures.

This study intends to investigate the effect of copper slag (CS) on the hardened properties of thermally damaged steel fiber-reinforced concrete. Two water-to-cement ratios of 0.5 and 0.55 are considered for the concrete mixture. Different volume fractions of 0, 0.5, 1.0, and 1.5 are considered for steel fiber. Thermal cycles of 28 and 56 are considered in the experimental program. Ultrasonic pulse velocity technique is used to monitor internal damages due to the thermal cycles. Overall results show that concrete mixtures containing copper slag have considerable thermal resistance compared to the reference mixtures. However, results recommend the optimum content of 1% for steel fiber, while further addition causes lower thermal resistance of CS-modified concrete. Also, regression equations are proposed for residual compressive and tensile strengths of thermally damaged CS-modified concrete. Results show good agreement between the experimental database and the proposed regression equations.

Improved autogenous healing capacity of concrete using superabsorbent polymers (SAPs) was used as an efficient approach for mitigating damage between steel rebar and self-consolidating conc...

Geothermal heat exchangers, one of the main components of shallow geothermal systems, have been investigated by many researchers in recent years to exploit clean and renewable energies. Most of the previous studies have mostly concentrated on the common types of ground heat exchangers including U-tube and helical ground heat exchangers. In the case of helical type, only two types of heat exchanger, with an inner outlet or with an outer outlet, have been examined. In order to increase the surface interaction between heat exchanger and backfill to improve the heat transfer rate, this study intends to present a new generation of helical ground heat exchangers called triple helix. Three helical branches are considered for both inlet and outlet of triple helix ground heat exchanger. The influences of geometric parameters such as helix pitch, helix diameter, helical coil length, the distance between centers of inner and outer helical coil branches, and the distance between centers of inner/outer helical coil branches on the efficacy of the heat transfer process are investigated by a numerical study. The results indicate that the most effective geometric parameter on the performance of the triple helix ground heat exchanger is the length of the helical coil, while the two parameters of the distance between centers of inner/outer helical coil branches, as well as the distance between centers of inner and outer helical coil branches, have the least effect. Along with the numerical results, multiple regression method accompanies with the artificial neural network are used to propose effective formulations to predict thermal properties of a triple helix ground heat exchanger.

Although theories of plates are accurate enough to use for thin plates, the three-dimensional elasticity analysis is needed to study the thick plates, which increases the computational efforts. The...

Previous research on steel bar-concrete bond behaviour has been concentrated mostly on the intact concrete without considering initial cracks induced by transverse tensile loading called pre-cracking phenomenon. There is no accurate model for evaluating bond behaviour and development length of steel bar in pre-cracked concrete. This paper aims to characterise the bond-slip behaviour of steel bars in pre-cracked concrete by direct pull-out tests, and proposes a constitutive law as a function of the crack width. Results show that induced cracks, notably cracks wider than 0.15 mm, cause a significant reduction in maximum and residual bond strength. Also, results indicate that larger crack widths result in considerably lower dissipated energy by the bond mechanism. The results obtained from both the experimental tests and referenced database demonstrate that the pre-cracking phenomenon has a higher impact on the residual bond strength compared to the maximum bond strength. Unlike existing equations, the proposed model accurately considers cracking effects on the steel bar-concrete bond properties and shows a satisfactory fit with the experimental database. A predictive equation is also proposed for calculation of the development length in pre-cracked concrete, which is more conservative and prudent compared to existing regulations in design codes.

Although extensive bond models have been developed for use in the numerical simulation of uncracked reinforced concrete, no simplified method exists providing satisfactory accuracy and effi...

Minimum concrete cover for rebar, rebar diameter, concrete compressive strength, embedded length of rebar, and lateral reinforcement by stirrups are the crucial factors considered in existing predicting equations and regulations for predicting rebar–concrete interface (RCI) bond strength. However, considerable effects of concrete composition on RCI are ignored in design codes and investigations. This paper intends to comprehensively highlight the critical aspects of this research gap. Additionally, a practical experimental approach is described in the present study to efficiently consider the effect of the new generations of concrete on RCI bond strength. Finally, nano-concrete is considered as a case study to show the importance of nanoparticle types on RCI bond strength. Overall results show that studying the microstructure of the transition zone at RCI is essential to accompany with the RCI bond strength for considering new generations of concrete in reinforced concrete structures. Additionally, the current study emphasizes that more investigations are necessary to be conducted by future works to fill the existing research gaps in RCI.

The addition of nanomaterials affects the workability of cementitious composites by reducing the free water available within the mixtures. In order to address this issue, the present study intends to study the addition of ground granulated blast furnace slag (GGBS) in cementitious materials containing graphene (G) and graphene oxide (GO). An experimental program is considered to measure fresh properties, compressive strength, and service life of cementitious composites. Dosages of 0.03% and 0.06% (by weight of cement) of G and GO are tested in cement pastes and mortars. GGBS in three different dosages of 15%, 30%, and 45% is investigated. A constant water/cement ratio of 0.35 is used in all mixtures. Results show that GGBS improves the yield stress and plastic viscosity of G- and GO-modified cementitious composites. Moreover, GGBS dosages of 30% and 45% compensate the reduced fluidity of 0.03 wt% of G- and GO-modified cementitious composites, respectively. The thixotropy of the composite paste containing GO decreases with the addition of GGBS. Moreover, comparable and slightly improved compressive strengths are obtained for mixtures containing GGBS. The results from the nomogram show a promising trend for the service life of mixtures containing G, GO, and GGBS.

This work discusses the input parameters of discrete element method (DEM) for defining contact element between concrete and rebar. A comprehensive study is performed from a numerical database built in this study. A targeted method of discrete element model considering key parameters of bond strength between concrete and steel bar is developed for reinforced concrete structures so that DEM is customized for defining bond-slip effect between rebar and surrounding concrete. Accuracy of hypothesis is validated by an experimental program. Results show that the targeted method of discrete element model is more applicable and precise than embedded element method in which the perfect bond with no slip is dominant between the materials.

Transmission line parameters are indispensable prerequisites for power system studies such as power flow analysis, state estimation, congestion management, protective relaying, etc. Since the line parameters vary in time due to various reasons such as environmental condition changes, online estimation of line parameters is thus crucial to assure reliable outcome of system studies. Phasor measurement units (PMUs), as the basis of measurement infrastructure in a smart transmission grid, turn out the online estimation of transmission line parameters feasible. In this paper, a practical method for online estimation of series-compensated transmission lines parameters is devised in which PMU and supervisory control and data acquisition data are jointly used. To do so, the nonlinear weighted least square error algorithm is employed. Additionally, the proposed method is extended to set forth the parameter estimation of three-phase model of a transmission line needed for unbalanced system studies. Unlike the existing methods, which necessitate PMU installation at both sides of the lines, the proposed method works with few PMUs and has admirable practical merits in nowadays power systems. Case studies through software and hardware simulation efforts demonstrate validity of the modeling approach.

This paper presents a summary of an experimental investigation and the derivation of a bond-slip model for reinforcing steel embedded in moderately confined concrete under monotonic and cyclic loadings. Moderately confined concrete encompasses the domain between unconfined and well-confined concrete, the limits of which are defined in the paper. The proposed constitutive law adapts and extends the well-known Eligehausen-Filippou model for well-confined concrete to moderately confined concrete. It is described by an envelope curve and degradation rules. The former is obtained through a confinement index, defined in this study as a function of the amount of confining steel and concrete, distance between confining steel and the rebar, and concrete segregation effect. It is proposed to adopt the same degradation rules used for well-confined concrete. These rules are validated through statistical tests for moderately confined concrete. They are found to predict correctly the main features of reduced envelope response under increasing cycling amplitudes but to underestimate response degradation under constant cycling limits for the subsequent cycles to the first cycle. To demonstrate the validity and limitations of the proposed model, its predictions under monotonic loading are compared with experimental results and analytical predictions from other studies.

There are no specific models for evaluating bond strength and development length of steel bar in unconfined self-consolidating concrete (SCC). Existing equations for steel bar embedded in normal concrete are not efficient and applicable for SCC. So, it is essential to introduce more precise and efficient models. In this study, pull out tests of referenced literatures are used to present new predicting equations. Unlike existing equations, proposed models demonstrate acceptable fit with the database. Also, in order to evaluate the accuracy of the proposed models, direct pull out tests are performed in this study. The results of experimental test are in good agreement with those obtained by proposed new models.

This paper presents an effective approach for parameters estimation of a series transmission line and power transformer. As opposed to existing techniques requesting synchrophasors at both ends of a given line, the proposed method relies on phasor measurement unit (PMU) data at one end and remote terminal unit (RTU) data at the other. From a practical perspective, this feature is crucial for present power systems with limited PMUs. Having derived the equations relating measurements to unknown parameters, the nonlinear least square error (NLSE) technique is used for the sake of estimation. The proposed method is based on the positive-sequence line and transformer models and can track the change of parameters with the environmental factors and load conditions. Results obtained from simulation studies verify the effectiveness of the proposed method.

This paper intends to study the effect of air-entraining admixture (AE) on self-healing method at rebar-concrete interface using superabsorbent polymer (SAP). AE with a constant dosage of 0.83 kg/m3, and 0.25% and 1.0% SAP dosages are considered. Two types of superabsorbent polymer with different chemical compositions and particle sizes are considered for the experimental tests. Pull-out test results of mixtures containing AE admixture are compared with those in non-AE concrete. Scanning electron microscopy/energy dispersive X‐ray spectrometry (SEM/EDS) along with microscopic analysis is performed to study the healing products at crack surface and SAP macro voids around the rebar. Overall, results indicate that AE admixture has a considerable impact on the performance of the self-healing method at the rebar-concrete interface especially for higher dosage of SAP (1.0%). This can be attributed to the internal voids networks around the rebar generated by AE admixture, which can ease the water transfer between SAP macro voids to participate in healing cracks after wet-dry cycles. SEM analysis shows that stalactites, healing products at the external surface of crack, are composed of a large amount of calcium and oxygen.

Although there are different models for determining bond strength and development length of glass fiber-reinforced polymer bar in normal concrete, they cannot evaluate the interfacial behavior of glass fiber-reinforced polymer bar in self-consolidating concrete accurately. This study presents more precise and efficient models for bond strength and development length of glass fiber-reinforced polymer bar in self-consolidating concrete than existing equations. The performance of a model depends very much on test data. Previous researches do not have enough data of bond strength and development length of glass fiber-reinforced polymer bar in self-consolidating concrete. So, more extensive data are needed to investigate the efficiency and accuracy of a model. To solve this problem, direct pull-out tests are performed in this study. Unlike existing models for bond strength and development length, proposed models perform very well for predicting bond strength and development length of glass fiber-reinforced polymer bar in self-consolidating concrete. The new models considerably decrease the deviation of existing models.

This study intends to determine the effects of incorporating superabsorbent polymers (SAP) within concrete on the bond properties of steel reinforcing bars (rebar) embedded in uncracked and pre-cracked concrete. An experimental program is conducted to check the performance of SAP, as a healing agent inside the concrete, in mitigating internal damage at the rebar-concrete interface due to the pre-cracking phenomena. Two types of SAP with different particle sizes (0.15 and 0.50 mm) and chemistries are considered in the experimental program. Pull-out test results show improved bond properties of steel rebars embedded in uncracked and healed concrete containing lower dosages of SAP. However, concrete containing a high dosage of SAP shows lower bond strength, compared to normal concrete, due to the presence of macro voids. A considerable healing effect is observed for the initial bond-slip curve portion, the bond strength, and the energy absorbed by the bond mechanism, within the cracks of pre-cracked SAP-modified concrete subjected to wet-dry cycles. This study shows that SAP can significantly increase the autogenous healing performance of concrete at rebar-concrete interfacial damage sites.

Employing discrete elements for considering bond-slip effects in reinforced concrete structures is very time consuming. In this study, a new modified embedded element method is used to consider the bond-slip phenomenon in structural behavior of reinforced concrete structures. A comprehensive parametric study of RC slabs is performed to determine influence of different variables on structural behavior. The parametric study includes a set of simple models accompanied with complex models such as multi-storey buildings. The procedure includes the decrease in the effective stiffness of steel bar in the layered model. Validation of the proposed model with existing experimental results demonstrates that the model is capable of considering the bond-slip effects in embedded elements. Results demonstrate the significant effect of bond-slip on total behavior of structural members. Concrete characteristic strengths, steel yield stress, bar diameter, concrete coverage and reinforcement ratios are the parameters considered in the parametric study. Results revealed that the overall behavior of slab is significantly affected by bar diameter compared with other parameters. Variation of steel yield stress has insignificant impact in static response of RC slabs; however, its effect in cyclic behavior is important.

This paper focuses on the parameter estimation of transmission lines which is an essential prerequisite for system studies and relay settings. Synchrophasor measurements have shown promising potentials for the transmission line parameter estimation. Majority of existing techniques entail existence of phasor measurement units (PMUs) at both ends of a given transmission line; however, this assumption rarely holds true in nowadays power networks with few installed PMUs. In this paper, a practical technique is proposed for the estimation of transmission line parameters while the required data are phasor measurements at one end of a given line and conventional magnitude measurements at the other end. The proposed method is thus on the basis of joint PMU and supervisory control and data acquisition (SCADA) measurements. A non-linear weighted least-square error (NWLSE) algorithm is employed for the maximum-likelihood estimation of parameters. The approach is initially devised for simple transmission lines with two terminals; then, it is extended for three-terminal lines. Numerical studies encompassing two- and three-terminal lines are conducted through software and hardware simulations. The results demonstrate the effectiveness of new technique and verify its applicability in present power networks.

The interaction between the steel bar and concrete is one of the most important issues that control the efficiency of the composite behavior. Accurate evaluation of the interaction between the reinforcement and the surrounding concrete can lead to more reliable finite element models. The implementation of a modified steel bar model in embedded elements to consider the bond-slip phenomenon is presented in this study. The procedure includes the addition of equivalent bond strain to the strain of the steel bar. This leads to a decrease in the effective stiffness of steel bar in the layered model. Validation of the modified steel bar model with existing experimental results demonstrates that the model is capable to consider the bond effects in embedded elements for use in analysis of reinforced concrete structure. A comprehensive parametric study is accomplished to obtain the influence of parameters such as concrete and steel properties, bar diameter, reinforcement ratio and confinement conditions on modification factors. Results revealed the significant effect of bond-slip on total behavior of the member.

A new synchrophasor-based fault location algorithm for series-compensated transmission lines is presented in this paper. Both prefault and fault voltage and current phasors associated with either ends of a given line accessible through the phasor measurement units (PMUs) are taken as input data. The proposed algorithm initially estimates the line parameters using prefault data; thereafter, these parameters are used for estimating the fault location. This method is based on the positive-sequence equivalent π models of transmission lines, and since PMU can measure prefault and fault positivesequence data in both symmetrical and unsymmetrical conditions, the method is applicable to all types of faults. The nonlinear weighted least square error (NWLSE) as a powerful method for tackling nonlinear estimation problem is used for the estimation process. Numerical case studies using MATLAB program demonstrate effectiveness of the new method.

In nowadays power networks, transmission companies are faced with a drastic growth in the electrical energy demand. As a result, further utilization of existing transmission lines capacity is very essential. Dynamic thermal rating (DTR), which is based on the actual weather and pre-load conditions, has a potential to offer a significant increase in a given transmission line capacity. Two types of DTR calculation methods, namely on-line monitoring of line temperature and weather-based rating, are discussed in this paper. The first method is the main contribution of this work and the second one is only reviewed. In the first method, phasor measurement units (PMUs) data are used for estimation of transmission line parameters and its temperature. In this method, a non-linear weighted least-square (NWLS) based algorithm is adopted for the estimation process. The second method uses weather stations data such as wind speed, ambient air temperature, etc., for calculation of DTR. A typical transmission line is simulated in MATLAB Power System Toolbox to demonstrate the performance of the proposed method for on-line monitoring of line temperature.

The growing focus on the energy efficiency promotion, deployment of renewable energy resources, and serving the electricity in more reliable ways have recently resulted in a remarkable attention on microgrids. Among different electricity generation options available for a microgrid, the one compromising both technical and economical aspects is of a great desire. Taking into account the existing uncertainties associated with energy resources, this paper evaluates various distributed generation (DG) configuration plans for a microgrid using analytical hierarchical process (AHP) approach. A variety of DG resources including photovoltaic and wind generation are incorporated in the analysis. Meanwhile, the uncertainties associated with solar radiation, wind speed, and fuel prices are considered. For the sake of numerical analysis, DG configuration plans are generated with the HOMER software; thereafter, the plans are assessed with the Expert Choice software that supports the AHP approach.