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Grade control structure (GCS) can be used to reduce erosion in river beds. They decrease the river bed scour by changing the flow regime and reducing its velocity. It is required to maintain the stability of these structures against the scour hole that generates downstream of them, so investigating the scour hole characteristics downstream of the GCS is inevitable. In the present research, the equilibrium scour holes downstream of GCS were investigated under three discharges (q=0.00467, 0.00583, 0.00700 m3/s.m) and two different sedimentation conditions (d50=0.082, 1.6 mm). The results show that in the constant GCS geometry and finer sediment, the maximum scour depth (ds) and maximum scour hole length (ls) increase. In the same sedimentary conditions and different geometry, when the slope of the GCS downstream face varied from 90° to 60°, ds increases, but ls decreases. Also, the hydraulic jump forms on the scour hole at high flow intensity, which has an essential influence on the geometry of the equilibrium scour hole. Comparison of ds/Hc between the present study and Ben Meftah and Mossa (2020) has R2=0.891 and RE=10.66%, which reveals acceptable compatibility between the present study results and previous ones.

Studying the influences of the debris settled by the flood upstream of the bridge pier on the scour is important. In the present study, experimental tests were performed as four models including the bridge pier, the bridge pier with buried debris, the bridge pier with the free debris, and the bridge pier with free debris and the bed sill with the downstream gap equal to 0, 1, 2, 3, and 4 times of pier diameter. The results showed that buried debris increased the maximum length of the scour hole (ls), and the maximum width of the scour hole (ws) by about 50, and 180% respectively in comparison with the alone pier. It resulted that buried debris has a more increased effect than free debris. Free debris at low submergence ratios reduces ls by up to 27%, and in high submergence ratios increases it by up to 37%. Also, free debris increases ws in all submergence ratios, which is by up to 127% for the critical case compared to the case without debris. At all distances, the bed sill reduces ls and ws, and the best performance for reducing ls and ws is when it is attached to the bridge pier. HIGHLIGHTS Predicting length and width of the scour hole.; Effect of debris blockage on pier scour was evaluated.; Utilizing bed sill for protecting pier with debris blockage.; Experimental approach was suggested for scour hole of bridge pier.;

Debris upstream of the bridge pier and through the flow variations, changes scour hole and river morphology. Dune forms downstream of the pier as a result of sediment movement in the pier scour phenomenon. The present study investigates the dune characteristics and geometrical parameters in experimental models. Experimental models are categorized into four cases including the pier, pier with buried debris, pier with free debris, and pier with free debris which was protected by bed sill at four various distances from the pier downstream face. It was concluded that debris submergence, densimetric particle Froude number, flow intensity, and bed sill affect dune geometrical parameters such as dune height (hd), dune crest position (xd), and dune length (ld). Results show dune height increases with debris accumulation up to almost 150% and its crest distance from the pier reduces up to approximately 100%. Also, in higher Fd, the dune height and its crest distance reduce with bed sill up to 50%, and in lower Fd, hd, and xd increase by up to 80% by using bed sill. Based on these effective parameters, three separate equations were proposed for hd, xd, and ld in pier scour with debris accumulation protected by bed sill.

Sluice gates are utilized in dams and irrigation channels as regulating structures in the channel have the role of regulating the water level for proper water intake of upstream intakes. As high velocity and energy of the flow issuing from these hydraulic structures scour occurred in erodible downstream beds. Occurrence of the hydraulic jump is very possible, and when it forms, therefore the necessity of investigating the flow condition increases. The scouring phenomenon is a time evolution and a long-time procedure. This research focused on time effects on experimental data received by a sediment bed profiler at different times from the experimental setup conducted in a laboratory. The maximum scour depth (dse), the maximum dune height (hd), the horizontal distance of the maximum scour depth from the beginning of the sedimentary bed (xse), and the horizontal distance of the maximum dune height from the beginning of the sedimentary bed (xd) were investigated. Laboratory observations show that the extension of the location of the maximum scour depth and the maximum height of the dune formed with time is evident. The laboratory data for the dimensionless conditions of 4 scour profiles characteristics including dse/b0, hd/b0, xse/b0, and xd/b0 were analyzed by the nonlinear regression method, and separate equations were proposed for each characteristic. RMSE=0.045, 0.0677, 0.358, and 2.146 respectively, and the R2 =0.996, 0.975, 0.974, and 0.977 respectively.

A low-profile broadband $2\times 2$ printed slot array with V-shaped slots by loading broadband artificial magnetic conductor (AMC) is demonstrated. A proposed wideband printed array with tapered V-shaped slots with the feeding of coplanar-waveguide (CPW) is measured in 8.24-11.13 GHz. Also, the proposed wideband planar AMC surface is embedded into the printed array to attain enhanced radiation properties. The printed slot array with the $7\times 7$ AMC surface covers -10 dB measured bandwidth from 4.47 to 13.32 GHz (100%). The design loaded by AMC compared to the design without AMC introduces a reduced size of 109.4%, a bandwidth improvement of 70%, and good impedance matching. Moreover, by adding an AMC surface into the printed array, an enhanced gain of 12.3 dBi with uni-directional radiation patterns is attained. The measured gain over the wide bandwidth shows acceptable stability with an average gain of almost 11 dBi. The proposed AMC unit cell is proposed to resonate at 10.10 GHz with a bandwidth of 7.85-12.24 GHz (43.7%) for X-band applications. In addition, the proposed equivalent transmission line model of the antenna with AMC is presented with acceptable output results. This model forecasts the input impedance of the printed array with AMC at the frequency band of 4.50-13.30 GHz as well.

Abstract A low‐profile printed dipole antenna (PDA) backed by a broadband Giuseppe Peano fractal artificial magnetic conductor (AMC) is introduced for wireless communications. A suggested PDA with a pair of microstrip dipoles excited by an E‐shaped microstrip feedline is used to expand the bandwidth range of 5.5–6.96 GHz (S11 ≤ −10 dB). Then, the suggested Giuseppe Peano fractal AMC surface as a reflector of the antenna is inserted into the PDA to improve radiation efficiency. The PDA with the 4 × 4 Giuseppe Peano AMC array exhibits −10 dB measured impedance bandwidth from 4.25 to 7.10 GHz (50.2%) for the wireless local area network and worldwide interoperability for microwave access (WiMAX) applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 50.5%, enhanced gain up to 8.2 dBi, and excellent impedance matching (at least −19 dB) with uni‐directional radiation patterns. The novel AMC unit cell is realized based on the Giuseppe Peano fractal patch to operate at 6.10 GHz with an AMC bandwidth of 5.15–7.10 GHz (32%). Besides, by loading a 4 × 8 AMC reflector into the two‐element array with diverse polarisations, a low profile wideband printed structure with enhanced radiation properties is achieved. The measured results show the broad bandwidths from 4.3 to 7.05 GHz for two elements with enhanced gains and good isolations between the elements (more than 28.5 dB) for multiple‐input multiple‐output (MIMO) systems.

In recent decades, brine discharge into the water bodies and desalination plants have increased dramatically all over the world. In this research, behavior of turbulent flow in submerged disposal of saline wastewater produced by coastal desalination with a nozzle oriented upwards at 45o to the horizontal was investigated by employing a three-dimensional laser-induced fluorescent (3DLIF) system. After obtaining experimental pictures and converting them to ASCI files, change of turbulent flow in jet-to-plume transition was analyzed through cross-sectional profiles of concentration, turbulent intensity and flow intermittency in different distances from the discharge nozzle with code development in MATLAB software. The results show that in this regime transition, agreement with Gaussian distribution in mean concentration profiles decreases for the inner side of discharged flow in the plume region, Concentration intensity increases and zero-intermittency zone decreases. Also, changes in slope of mean concentration, concentration fluctuation intensity and intermittency along the centerline increase dramatically.

Feedwater supply for coastal desalination plants, powerplants and other coastal industries using marine intakes has become a common approach during last years. Besides providing water with high quality, intake design should be economically and environmentally acceptable too. The intakes are generally divided into two groups i.e. direct and indirect intakes. The efficiency of direct intakes is a function of sea conditions such as the changes in seawater level and the hydrodynamic of the waves and tides. In deep intakes, the size of the cap, changes in seawater level, and consequently changes in water inflow are challenging design parameters. Seawater level changes due to tides, and the potential effects of climate change and global warming can disrupt the functionality of deep intake systems. In this study, the effect of sea-level changes on the performance of deep intakes has been investigated by studying the hydraulics of the velocity cap along the nearfield. So, an experimental and computational fluid dynamics model has been developed to investigate flow regimes at the location of the velocity cap, vicinity of the surface, and at the sea floor. Density stratification, wave effects, and ambient current have been ignored, so the simulations only developed for stagnant and non-stratifield conditions.

A low-profile printed dipole antenna (PDA) backed by broadband rhomboid artificial magnetic conductor (AMC) is introduced for vehicular wireless communications. Firstly, a suggested PDA with a pair of the microstrip E-shaped dipoles is fed by an E-shaped microstrip feedline to expand the bandwidth in the measured range of 5.5-6.96 GHz ( $\text{S}_{11}\le -10$ dB). Then, the suggested rhomboid AMC reflector is inserted into the PDA to gain improved radiation efficiency up to more than 90%. The PDA loaded by the $3\times 3$ rhomboid AMC array with the size of 48 mm $\times48$ mm $\times6.8$ mm exhibits −10 dB measured impedance bandwidth from 4.48 to 7 GHz (almost 44%) for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 42.3%, enhanced gain up to 8.4 dBi, and excellent impedance matching (at least −20 dB) with uni-directional radiation patterns. The novel AMC unit cell is realized based on the recognized method as rhomboid coupled parasitic patches. The rhomboid AMC design operates at 6.20 GHz with an AMC bandwidth of 5.10-7.18 GHz (34%). Also, by loading $3\times 4$ and $5\times 5$ AMC reflectors into the two-element and four-element array of PDA, low-profile wideband structures with enhanced radiation properties are achieved. The measured S-parameters show the broad bandwidth from 4.48 to 7.12 GHz in C-band with enhanced gains and efficiencies (more than 90%) of multiple elements. Besides, the suitable isolation between the array elements of more than 30 dB for multiple-input multiple-output (MIMO) systems is achieved by applying various polarized directions of PDAs and loading periodic AMC reflectors.

The purpose of this paper is to investigate the behavior of positive buoyancy jets of urban wastewater in stationary and non-stratified water bodies using the investigation of the laboratory data acquired by a 3D-LIF laser 3D scanning system and numerical modeling results from the simulation by FLOW-3D software. Laboratory simulation was performed for three discharge jets with Froude numbers 10, 15, and 20, and compared with the results of the numerical model and the previous numerical results. The trajectory of the jet, concentration variations, the position of the impact point, and the rate of dilution at the impact point was determined. In the numerical model, both K-Ɛ and RNG turbulence models were used to evaluate the accuracy of the numerical simulation where the K-Ɛ results were closer to laboratory results and are capable of accurately modeling the jet trajectory than the RNG model. By different Froud numbers, the results at Fr = 20 are almost the same for all experimental and numerical states and indicating that by increasing the discharge and Froud number, the accuracy of the results in the numerical model increases and present closer results to the experimental model.

This paper presents the effect of hydrodynamic parameters of the two-body converters of a point wave absorber on the amount of power output. This converter includes two submerged and floating bodies which are connected to the spring-damper system. The whole of the converter is connected to the sea bed by mooring catenary. The relative displacement of the floating body and the submerged body is the main factor in generating electrical energy. Since the calculation of hydrodynamic coefficients has a significant effect on the solution of dynamic equations, this study focused on the calculation of added mass and hydrodynamic damping by boundary element method using the ANSYS-AQWA software. Also, this paper investigates the effect of floating borehole geometry on the hydrodynamic parameters and the extracted power of the converter using complementary analysis on the domain of time and frequency. Comparison of numerical simulation outputs and the results from the laboratory work which had carried out by Sandiego researchers in 2011, shows the suitable accuracy of the simulation. According to the results, with the two meters increase in buoy diameter, the power output will increase by 20%, and the output power for the half- conical is 17% more than the hemisphere.

BACKGROUND Gastroesophageal reflux disease (GERD) is a common problem with annoying symptoms. It is associated with negative impact on quality of life. Prokinetic agents may be used in combination with acid suppression agents as an adjunctive in patients with GERD refractory to proton pump inhibitors (PPI) therapy, rather than as sole treatment. This study aimed to evaluate the efficacy of combination of PPI with domperidone (a prokinetic agent) compared with PPI alone in the treatment of patients with refractory GERD. METHODS This study was a double blind clinical trial on 29 patients with GERD refractory to PPI during the period of one month. By randomization, the patients were divided into two groups. Group A was treated by pantoprazole 40 mg twice daily and domperidone 10 mg three times a day for a month, while group B was treated by pantoprazole 40 mg twice daily and placebo three times a day. In this study endoscopy was performed to evaluate the prevalence of erosive esophagitis, nonerosive reflux, and hiatal hernia. Manometry was conducted to study the prevalence of dysmotility. GERD symptom questionnaires including the Gastrointestinal Symptom Rating Scale (GSRS), Carlson Dennett, and the Medical Outcomes Study Short Form-36 health survey (SF36) were used before and after treatment for screening GERD and assessing treatment response. RESULTS There were 17 (58.62%) women and 12 (41.37%) men. The prevalence of erosive esophagitis and non-erosive reflux, was 10.34% and 89.66%, respectively. There was a significant difference comparing reflux symptoms before and after treatment between the two groups according to reflux and Carlson Dennett questionnaires. At the end of the study, symptoms of reflux significantly improved by treatment. Although, the quality of life questionnaire scores improved by treatment, there was no statistically significant difference in response to treatment between the two groups. CONCLUSION In this research, we showed that adding domperidone to PPI could not make any improvement in patients with refractory reflux regarding the quality of life and improving the symptoms.

Abstract An unusual dust event over the Atacama Desert occurred in July 2016. Here, a synoptic study of the event is carried out using the NCEP FNL analysis data and WRF‐chem simulations. The “zonalization” of a mid‐tropospheric trough leads to the formation of a horizontal convergence band over the Northern Atacama and thus downward wind below it. As the descending air masses warm adiabatically, strong temperature contrasts to the colder air over the western Andes occur and intensify the down‐valley winds, thus leading to extraordinary strong easterly winds in the Atacama. Simulations with WRF‐chem indicate that these surface winds are sufficient for large‐scale dust emission, and simulated dust plumes traveling far over the eastern South Pacific agree well with the observations. As the integrated dust load is comparable with the load observed in major dust sources of the world, our findings highlight the importance of such unusual events.

In modern microwave telecommunication systems, especially in low phase noise oscillators, there is a need for resonators with low insertion losses and high Q-factor. More specifically, it is of high interest to design resonators with high group delay. In this paper, three novel dual-band complementary split-ring resonators (CSRRs) featuring high group delay etched on the waveguide surface by using substrate integrated waveguides are investigated and proposed. They are designed for a frequency range of 4.5–5.5 GHz. Group delay rates for the first, second, and third resonators were approximated as much as 23 ns, 293 ns, and 90 ns, respectively. We also proposed a new practical method to develop a wide tuning range SIW CSRR cavity resonator with a small tuning voltage in the second resonator, which leads to about 19% and 1% of tuning frequency band in the first and second bands, respectively. Finally, some of their applications in the design of filter, diplexer, and low phase noise oscillator will be investigated.