Iran, due to its geographical location, has low rainfall and is considered a dry land. As a result, different regions of the country grapple with drought. The presence of water management systems, such as aqueducts and reservoirs, in most parts of the country, along with a variety of methods for conserving water for irrigation, may contribute to this claim. Considering that drought is an inherent phenomenon in Iran's climate, people have invented and used numerous methods to combat it and store water. The aim of this study is to monitor and evaluate drought in Iran. In order to realize this goal, precipitation data from synoptic, rain gauge, and climatology stations were extracted over a 51-year period, from 1970 to 2020. The results obtained from examining drought occurrences in five ten-year periods reveal that, with the exception of the third decade (1991 to 2000), drought has prevailed in the majority of Iran's regions compared to other decades. On the other hand, in the recent decades leading to 2020, the intensity of drought occurrences, especially in the Middle Zagros, has intensified, which has consistently been among the regions with the highest rainfall in Iran after the Caspian region. This situation can cause concern in Iran, a country where its agricultural production hub is established along the Zagros mountain range. Moreover, the fluctuating behavior of Iran's droughts, with return periods of 2 to 5 years, has complicated the management strategies for these types of hazards. These conditions appear to have created numerous issues in many areas of Iran, particularly in the agricultural sector of the western provinces, due to the lack of conformity with these types of occurrences.

A 55-year-old man presented with decreased urine output and altered sensorium of a week’s duration. On examination, asterixis was present. Examination of his hands revealed pinkish bands on the distal part of his nails with whitened proximal nails. Further evaluation revealed deranged kidney function tests (blood urea, 189 mg/dL and serum creatinine, 8.8 mg/dL) and bilaterally shrunken kidneys. A diagnosis of chronic kidney failure with renal encephalopathy was established and the patient initiated on haemodialysis, and later he was discharged. ...

The increasing number of reinforced concrete structures affected by corrosion makes the study of their protection an import parameter. Usage of different types of surface coatings on rebars for the corrosion protection has not proved to be a reliable system on account of many reasons like reduction in bond stress between the concrete & rebar and so on. The standard procedure of rehabilitation of corrosion affected structural elements. viz., chipping the cover concrete, exposing the rebar, cleaning rebars, applying corrosion protection coating to the rebar, providing formwork, pumping of micro concrete, etc becomes labour intensive and uneconomical in addition to a lot of disturbance caused to the occupants. Hence, sacrificial anodes are being increasingly used during the rehabilitation of corrosion affected Reinforced Concrete (RC) structures. The self regulating anodes comprise of zinc metal covered with porous matrix, which sacrifices itself and protects the corrosion of rebar. The paper presents the results of the study carried out on the performance of sacrificial galvanic anodes installed in RC structural elements with and without preconditioning methods.

Previous researches have shown that due to its good adhesion, alkali-activated materials can be used as a protective overlay for concrete structures. However, the mechanical properties and durability of alkali-activated materials are not fully investigated. In this paper, compressive strength, bond strength, water penetration and half-cell corrosion potential of alkali-activated slag and pumice mortars as concrete overlay are investigated. The results show that the performance of alkali-activated slag mortar is better than Portland cement one in above tests and the use of potassium hydroxide as activator and a mixture of 90% slag and 10% pumice as based material result in the highest compressive strength and bond strength and the lowest water permeability and half-cell corrosion potential. The initial half-cell potential reading of alkali-activated mortar specimens was an average of 1. 9 times more than Portland cement mortar specimens. This difference indicates that the ranges presented in ASTM C876 and their relationship with rebar corrosion risks are not applicable for alkaliactivated materials and it is necessary to provide other criteria for these materials. Also, due to different conductivity of alkali-activated and Portland cement mortars, applying potential difference to accelerate the penetration of chloride ions and comparing the performance of alkali-activated materials with Portland cement is not a correct method. However, this method is suitable for comparing mixes design of alkali-activated mortars and its results are in accordance with non-accelerated methods.

In this study, a three-dimensional model of a single fuel cell is considered. This modeling is done for a cathode half-fuel cell and consists of a parallel flow field, namely a cathode gas diffusion layer and a polymer membrane; it includes mass transfer at gas diffusion layer, electrochemical reaction at catalyst layer, and charge transfer in all the parts of fuel cell. Shoulder is considered in this model and thus concentration profile and charge distribution are more delicate. Governing equations are solved by FEMLAB software through the finite element method. This modeling could predict the behavior of fuel cell at different operation conditions by minimum cost. The performance of fuel cell is evaluated by different activation energies and, by comparing the results, the optimum operation condition is concluded.

In this paper a miniaturized diplexer for WLAN and WiMAX applications is presented, based on half-mode substrate integrated waveguide (HMSIW) technology by loading a novel metamaterial unit-cell. The proposed metamaterial unit-cells are called fractal open complementary split-ring resonators (FCSRRs). The proposed FCSRRs behave as electric dipoles if appropriately stimulated, and are able to generate a forward-wave passband region below the cutoff frequency of the waveguide structure. The electrical size of the proposed FCSRRs unit-cell is smaller than the conventional CSRRs unit-cell. Therefore, the FCSRR unit-cell is a good candidate to miniaturize the SIW structure. The proposed diplexer has been designed by cascading two bandpass filters with different center frequencies. The HMSIW bandpass filters are implemented by etching two FCSRR unit-cells with different sizes. The design procedure is based on the theory of evanescent mode propagation in which the FCSRR unit-cells behave as electric dipoles. A forward-wave passband below the intrinsic cutoff frequency of the HMSIW structure has been achieved by loading the FCSRR unit-cells on the metal surface of the HMSIW structure. This proposed diplexer displays high selectivity and compact size by using sub-wavelength resonators. The designed diplexer has been fabricated and experimental verifications have been provided. The measured results are in a good agreement with the simulated ones. The total size of the proposed diplexer is about 0. 30 λ g × 0. 09 λ g. The proposed diplexer shows significant advantages in terms of size reduction, low loss, high selectivity, high Q-factor, easy bandpass frequency shifting, easy fabrication and easy integration with other planar microwave circuits.

In this study, the effect of cement content on concrete performance in corrosive environments is investigated on concrete mixtures having the same water/cement (w/c) ratio. Three w/c ratios (0.40, 0.45 and 0.50) were used and for each w/c ratio three mixtures were prepared with cement contents 350, 400 and 450 kg/m3. The compressive strength, electrical resistivity and chloride diffusivity of the samples without steel reinforcement were determined. In addition, the half-cell potential of samples with steel reinforcement in 5% NaCl solution was measured to evaluate the rebar corrosion. It is found that although w/c ratio is kept constant, strength increases and corrosion probability of steel reinforcements decreases when cement content in the mixture decreases from 450 to 350 kg/m3.

The problem of propagation of plane wave including body and surface waves propagating in a transversely isotropic half-space with a depth-wise axis of material symmetry is investigated in details. Using the advantage of representation of displacement fields in terms of two complete scalar potential functions, the coupled equations of motion are uncoupled and reduced to two independent equations for potential functions. In this paper, the secular equations for determination of body and surface wave velocities are derived in terms of both elasticity coefficients and the direction of propagation. In particular, the longitudinal, transverse and Rayleigh wave velocities are determined in explicit forms. It is also shown that in transversely isotropic materials, a Rayleigh wave may propagate in different manner from that of isotropic materials. Some numerical results for synthetic transversely isotropic materials are also illustrated to show the behavior of wave motion due to anisotropic nature of the problem.