Introduction: Prediction of scour and characteristics of scour hole due to out flow from hydraulic structures is important in the hydraulic engineering. The dimensions of scour hole are influenced by different parameters including: flow discharge, drop height of flow, tailwater depth, sediment size, sediment load and time of scouring. Almost all the previous studies have focused on the scour hole characteristics downstream of free over fall clear water jets. Water jets are not always clear and may carry sediment, especially during flood condition, and the effect of sediment load on the scour characteristics are not well studied. Therefore, in this study, scour downstream of a free over fall clear and sediment-carrying water jets are studied experimentally. The main purposes of this study are to analyze the effects of important parameters including sediment load, sediment size and discharge of the free falling jet on the scour depth and the longitudinal scour length. The temporal variation of the sour depth and longitudinal scour length were also addressed. New dimensionless equations for scour depth and longitudinal scour length were obtained. Methodology: Experiments were conducted in a rectangular channel of 0. 6 m width, 12 m length. The water was pumped from a sump to the channel. A rectangular free-overfall jet of 0. 21 m width was established at the last 1 m length of the channel. Scour was simulated in a rectangular box of 1. 5 m width and 2. 51 m length, which is located downstream of channel. Measurement of discharge was done by using a calibrated sharp crested triangular weir with 90 degree apex angle. The depths of flow and longitudinal bed profiles were measured by using a digital point gauge with ± 0. 01 mm theoretical accuracy. Temporal measurement of longitudinal bed profiles were also done by using the same digital point gauge. The rectangular box was covered by uniform sand layer with 0. 45 mm thickness. Experiments were performed for four different discharges (4. 27, 7. 48, 11. 78 and 17. 3 L/s) and two sediment sizes (d50 = 0. 6 mm and 1. 2 mm). Experiments were conducted with clear water free falling water jet and sediment caring free falling water jet. In experiments with sediment caring free falling jet, the dry sediment with constant rate was added to the water jet by using a sediment fidder. Four values of sediment load: 0. 25, 0. 5, 1 and 2 kg/min were used. The added sediment to the jet was of the same size as the downstream bed material size (d50 = 0. 6 mm and 1. 2 mm). Time variations of the scour depth and length of scour hole were also studied. Results: Based on the result, by increasing the sediment load, the values of maximum depth of scour and length of scour hole decreased. The rate of scour reduction depends on the amount of sediment load in the water jet, water discharge and duration of scour. By increasing the duration of experiments, the increasing effects of densimetric Froude number and jet discharge in the longitudinal bed profiles reduces. The decreasing trend of sediment load on the maximum scour depth is more pronounced in experiments with lower duration. In higher discharges, the reducing effect of the sediment load on the maximum depth of scour reduces. The reducing effect of sediment load on the longitudinal scour length is reduced for higher water discharge. The reducing effect of sediment load on longitudinal scour length is enhanced in experiments with lower duration. Effects of dimensionless parameters on the scour depth and scour length were addressed. By increasing the densimetric Froude number, the relative depth of scour and relative longitudinal length of scour hole increases. The dimensionless equations for estimation of the longitudinal scour profile, scour depth and scour length are obtained. Conclusion: In this experimental study, the scour depths and the longitudinal scour lengths were compared in the clear water and sediment caring free falling water jets. It was found that by increasing the sediment load, the values of maximum depth of scour and length of scour hole decreases. The rate of scour reduction depends on the amount of sediment load in the water jet, water discharge and scouring time. New equations for estimation of the longitudinal scour profile, scour depth and scour length are also developed.

This article aims to carry out a critical study of certain deterministic approaches to the result of some of the neuroscience experiments, including the Libet experiment. In these experiments, the choices leading to action are investigated and demonstrated to originate from parts of the brain that are beyond our control and will. Following an explanation of the experiments, the paper offers a logical analysis of their results. Then, reasons are presented to criticize deterministic results based on Libet’s experiments. Among other things, it is shown that Libet's test and the results obtained from it are faced with the following problems: inappropriate generalization of the test and its results to all the conscious actions of people, non-spontaneity of the performance of the test subjects, lack of time accuracy, and unconscious intention. Finally, the paper shows that the results of neuroscience experiments are too ambiguous and cannot be used to reject free will.

This paper focuses on higher order modeling and design of the free-piston Stirling engine (FPSE) based on Ant Colony Optimization(ACO). First, the governing thermodynamics and dynamical equations of the engine have been derived. Then, thedesign parameters of the engine are selected taking into account the finite heat transfer coefficient (resulting in a fifth-ordermodel) and pressure drop (resulting in a sixth-order model) in the dynamical system and the corresponding differential equationsare derived in detail. In the following, the mentioned methods and their performance in modeling the FPSE dynamicsare investigated. The simulated results show that the effect of the pressure drop on the places of the closed-loop poles of thesystem is not significant, while the heat transfer coefficient has a considerable effect on the engine dynamics. Accordingly, a fifth-order model along with ACO algorithm is proposed to justify the FPSE behavior. To validate the presented modelingscheme, the prototype engine SUTECH-SR-1 was experimented. It is found that the values of parameters obtained from theproposed design method are close to those of the experiment. Besides, the presented higher order model predicts the enginebehavior with an acceptable accuracy through which the validity of the design technique is affirmed.

Introduction Most of the times, flow passing above, through or below hydraulic structures is in the form of jets, which can cause downstream soil material erosion. When the amount of clay in soil materials is more than 10%, they can be considered as cohesive soils. If the results of cohesionless sediment research are generalized to cohesive sediments, the scour values obtained will be more or less than the actual values. On the other hand, there are no specific conversion ratios to estimate the characteristics and temporal changes of the scouring of cohesive sediments from cohesionless sediments. The duration of reaching maximum scour depth in cohesive sediments has shown to be longer than that of cohesionless ones.Previous works on cohesive sediments are often performed on flumes or by using a submerged vertical jet device. However, the jets formed below the hydraulic structures are mostly horizontal or oblique which are examined in this paper.Based on dimensional analysis, it was determined that the parameters of nozzle diameter, jet drop height, jet angle, jet velocity, tailwater depth, fluid density, dynamic fluid viscosity, critical shear stress and gravity acceleration affect the scour of cohesive sediments caused by the jet which is studied here.Methodology Experiments were carried out at the Hydraulic Lab of Tarbiat Modares University in a rectangular flume 0.6 m wide and 0.6 m high. A 0.2 m deep hole is created on the floor to place cohesive sediments. The laboratory channel is equipped with a 2m3 inlet tank, from which water is pumped into the jet tube. Froude numbers 3, 5, 7, and 9 are established based on common hydraulic structures and previous works.The experiments were performed using horizontal, oblique and vertical jets using tubes with nozzle diameters of 10, 15, 20 and 25 mm and with 3 tailwater depths of 5, 10 and 15 cm and 3 jet drop heights of 20, 50 and 60 cm. The cohesive sediments used were produced from a combination of fine sand with clay (including kaolin and bentonite at a ratio of 3 to 1). The amount of clay was considered to be 20% by weight of the total soil based on natural soils and previous works.Prior to the start of tests, tailwater was established on the sediment layer in order to allow it to saturate. After reaching equilibrium in the experiments, water was completely drained from the channel and the scouring hole and bed profiles were extracted by a laser distance meter device.Results and Discussion Erosion of cohesive sediments has the greatest scouring potential in the initial stage and in the later stages, the sediment bed becomes rougher and its resistance to scouring increases until equilibrium establishes.A sedimentary ridge is formed at the end of the scouring hole by horizontal and oblique jets and around the scouring hole by vertical jets. In horizontal and oblique jets, the maximum scour depth does not necessarily form on the centerline. The growth of the length and width of scouring hole stops almost simultaneously, but deepening of it continues after that. This is in accordance with findings of Mazurek et al. (2001), Ansari et al. (2002), and Mazurek et al. (2003).As the jet height rises, the time it takes to reach equilibrium increases and leads to maximum scouring occur at a greater distance from the jet nozzle. In horizontal jets, the location of the maximum scouring depth shifts in the early stages of scouring but stabilizes after approximately 2 hours. Increased shear stress due to jet flow increases the scouring rate.Increasing the ratio of tailwater depth to jet drop height (Yt / H) has a dual effect on the maximum relative scour depth. So that the maximum relative scour depth first increases with increasing Yt / H to about 0.3 for horizontal jets and about 0.35 for vertical jets, then the trend reversed and with increasing Yt / H ratio the scour rate relatively reduced. Increasing the Froude number increases the amount of scouring. Also, the amount of scouring at two angles of 0 and 30 degrees relative to the horizon, are very close to each other. At larger angles, except for the 90 degree angle, the scour depth increases as the jet angle increases. The 45 degree angle jet creates the maximum scouring depth.Conclusion As the jet height rises, the time it takes for the scouring to reach equilibrium increases. It also leads to maximum scouring to occur at a greater distance from the jet nozzle. Increasing shear stress by jet flow, increases the scouring rate.At lower values of Yt/H, with increasing this ratio, the maximum scour depth increases until it reaches the maximum value and then. the trend reverses.By increasing Froude number, scour rate increases. By steepening jet angle, the scour depth almost increases but when the jet becomes vertical, lower scour depths are observed.

Introduction The olive fruit (Olea europaea L. ) is so sensitive to impact like many other crops that would lead to mechanical damage and bruising which reduce the quality of it. The olive fruit damage includes a brownish bruise at the bruised location. Most mechanical impact damage occurs during harvesting, handling and transportation. Bruise sensitivity of two common olive cultivars in Iran (cv. Roghani and cv. Conservolea) was studied by free fall method because of development of the area under olive cultivation in Iran, and necessity to mechanical harvest in near future. Materials and Methods Two cultivar of olive fruit named Conservolea and Roghani were collected from Research Orchard of Horticultural Department of Isfahan University of Technology. A free-fall device was designed and built to accomplish an impact experiment which included a load cell monitoring system to measure impact force. The effect of cultivar, height and mass were studied in a factorial experiment. The factors consisted of two cultivar, height at five levels, and mass at three levels with 10 replications. The experiments were performed according to completely randomized design. The effect of impact force and absorbed energy was also studied for the two cultivars. The dimensions of bruising was measured 24 hours after the tests by a caliper with an accuracy of 0. 01 mm. The bruising area and volume was calculated assuming the elliptical model for the bruised region. Experimental data were subjected to analysis of variance (ANOVA). Mean comparison was performed based on least significant difference (LSD) test with P<0. 05. Results and Discussion For both cultivars the bruising occurred under the skin and near to the stone. This could show the effect of stone at bruising. The shape of bruised region was elliptical in cv. Roghani and spherical in cv. Conservolea. The bigger stone index and the lower flesh width of cv. Roghani might be one of the reasons of more volume of bruising in this cultivar. This variety could be due to less sphericity in cv. Roghani than cv. Conservolea. The distribution of bruising was more in Roghani cultivar since it had more oil and less water content that might led to more bruising distributed under impact condition so the volume of bruising was more than Conservolea cultivar. The effects of cultivar, height and mass were significant on area and volume of bruising. Increasing height and mass significantly resulted to increase the area and volume of bruising for both cultivars. The bruise area and volume were significantly higher in cv. Roghani. This could be due to differences in physical properties of the cultivars. Roghani cultivar had a higher pit/flesh ratio in comparison with Conservolea cultivars that could contribute to more area of bruising in this cultivar. Increasing the force and energy led to increase in bruise volume for both cultivars. In cv. Roghani, despite the lower levels of force and energy, the bruise volume was more than cv. Conservolea. The reason of lower energy and force in cv. Roghani might be as a result of lower mass than cv. Conservolea. Conclusions The results showed that the effects of independent variables were significant on the volume and area of bruising so that, increasing height and mass increased the volume and area of bruising. The Roghani cv. was significantly more sensitive to bruising compared to Conservolea cv. The energy and force levels were higher in cv. Conservolea since it was heavier than cv. Roghani while the volume of the bruise was more in cv. Roghani. This might be due to the lower sphericity and flesh/pit ratio in cv. Roghani. The shape of mechanical damage which was appeared with a brownish bruising on olive tissue was related to the geometric shape of the fruit i. e. for cv. Roghani and cv. Conservolea the bruising was elliptical in and spherical just like the geometric shape of the cultivars.

Automated storage and retrieval systems (AS/RSs) are material handling systems that are frequently used in manufacturingand distribution centers. The modelling of the retrieval– travel time of an AS/RS (expected product delivery time) ispractically important, because it allows us to evaluate and improve the system throughput. The free-fall-flow-rack AS/RShas emerged as a new technology for drug distribution. This system is a new variation of flow-rack AS/RS that uses anoperator or a single machine for storage operations, and uses a combination between the free-fall movement and a transportconveyor for retrieval operations. The main contribution of this paper is to develop an analytical model of the expectedretrieval– travel time for the free-fall flow-rack under a dedicated storage assignment policy. The proposed model, which isbased on a continuous approach, is compared for accuracy, via simulation, with discrete model. The obtained results showthat the maximum deviation between the continuous model and the simulation is less than 5%, which shows the accuracyof our model to estimate the retrieval time. The analytical model is useful to optimise the dimensions of the rack, assess thesystem throughput, and evaluate different storage policies.

Steel sheets are used in various industries such as automotive, aerospace, and …, . The issue of impact and penetration in steel sheets has been the main focus of many studies. In this study, Laboratory and numerical studies of flat and reinforced steel sheets by steel reinforcement have been performed under the of impact caused by free fall of the weights. Steel sheets used are steel St12. The material and thickness of the pendentive used are similar to the sheet and have a width of 2 cm. The parameters have evaluated include the amount of impact acceleration on the sheet, the rate of permanent deformation, and the amount of energy absorption for simple and reinforcer flat sheets. The numerical modeling of Abaqus finite element software is used. The results show that the use of reinforcer causes a slight increase in the acceleration of the sheet and a significant reduction in its permanent deformation.

One of the possible solutions for the challenges caused by the use of private passenger cars, especially traffic, congestion, and air pollution in Tehran, avoiding huge economic costs and reducing the annual death rate, is to apply the approach of "city center without private passenger cars". The purpose of this study is to measure the stated preferences of Tehrani citizens to identify the non-market influencing components and the economic valuation of these components based on the discrete choice experiment approach and conditional logit models. The findings of the present study revealed that the "additional green and recreational space" is more significant compared to other components. The components of "parking facilities at the border of the area" and "abundance of public transportation" within the area of the city center without a car are the next priorities, and the heterogeneity in the preferences of Tehrani citizens is in addition due to these two components. Noteworthy that the source of this heterogeneity is also the demographic variables "income" and "age" of people. In the analysis and interpretation of the estimated values of "willingness to pay", noteworthy that Tehrani citizens attach relatively less significance to the components of designing a cycling path and reducing the average walking distance to the nearest station. On the other hand, they prefer components of "designing additional green and recreational space within the area", "designing parking facilities at the border of the area" and "more public transportation within the area"; In such a way that the willingness to pay them is 44,375, 30,000 and 28,125 rials, respectively, which is approximately one and a half to two times the current fares. Therefore, it is recommended that in the traffic policy for the city of Tehran, the two components "designing additional green and recreational spaces within the area" and "designing parking facilities on the border of the city center without cars" should be of higher priority than other components.

This paper numerically investigated the influence of falling height on the behavior of the skid-launching free-fall lifeboat (FFLB) in regular waves. The boat has been treated as a rigid body when the differential equations of motion for the four falling phases, i.e., sliding or ramp phase, rotation phase, free-fall phase and water entry phase of the lifeboat were solved in the time domain. The hydrodynamic characteristics of the lifeboat has been studied for different falling heights such as H=1.5m, 1.75m and 2.00m. Horizontal and vertical excursions and the rotation of the axis of the boat have been computed at different time along with its horizontal and vertical velocities.Hydrodynamic forces and accelerations at normal and axial directions have also been determined. At first the analysis has been done in still water and then in regular wave with amplitude of 0.5m and a period of 2.0 sec. In all of the cases, effects of regular wave are shown by comparing the results with those considering the falling of FFLB into calm water.