Combination of weir and gate as a hydraulic measuring structure has advantages such as passing the float and settling materials (ice, wood, sediments, etc) simultaneously in compression using weir and gate separately. The flow through combined devices may be submerged when the downstream water level affect on discharge coefficient. In this study, the authors describe new experiments of both submerged cylindrical and sharp edge weir-gate to investigate the effects of geometric and hydraulic parameters on flow discharge. The experiments have been done on rectangular and horizontal small laboratory flume with fore cylinder sizes and also same sharp edge sheet for several flow rates and downstream water level. The results demonstrate that the discharge coefficient are affected by ratio of upstream depth to gate opening H/a, the ratio of upstream depth to height of structure H/P and the ratio of downstream water depth to upstream depth. Also, two submergence limits can be defined for combinational model. The first one depends on gate and it occurs when HTW/H=0.55-0.65 and the second one belongs to weir in HTW/H=0.8-0.85. Moreover, in the both sharp- edged and cylindrical combination models with increasing the submergence ratio, the trend of discharge coefficient decreases similarly and in a constant submergence ratio, the relative discharge coefficients of both models are similar.

The paper deals with the notion of quasi bi-slant submersions from almost contact metric manifolds onto Riemannian manifolds. These submersions are generalization of hemi-slant submersions and semi-slant submersions. We study such submersions from Kenmotsu manifolds onto Riemannian manifolds and discuss some examples of it. In this paper, we also study the geometry of leaves of distributions which are involved in the definition of the submersion. Further, we obtain the conditions for such submersions to be integrable and totally geodesic.

Submersion and subsequent drowning in children and adolescents is a preventable unintentional accident which may result in death and neurological injuries due to hypoxia and ischemia. The aim of this study was to determine the epidemiologic pattern of drowning and near-drowning among children and adolescents admitted in Kashan Beheshti Hospital during 1993-2005. In this descriptive study the medical records of all drowned and near-drowned cases admitted in Beheshti Hospital during a 12 year period were studied. All data (e.g., sex, age, nationality, season of the event, location of the drowning, any drug usage, background disease and the fate of victims) were collected and analyzed carefully. Among all 47 victims, 6 (12.8%) were drowned and remaining 41 (87.2%) were near–drowned. Thirty-three (70.2%) of the cases were male and children (aged 1-4 years) with the highest rate of submersion. Male drowned victims at all ages were more than the females. The nationality of 40 and 7 of the cases were Iranian and Afghani, respectively. The most common sites of submersion were ponds (72.5%), swimming pools (8.5%), streams or rivers (8.5%), wells (4.2%) and others (6.3%). The most common seasons of drowning were spring and summer each one with a rate of 27.7%. There was no history of drug consumption or background diseases in drowned or near drowned victims. Thirty-nine (83%) out of the total (47) cases, completely recovery and 8 (17%) were expired. While all the drowned children were expired, near-drowned, except for 2, were survived. Mortality was more common in children (aged 1-4) male Iranian victims for submersion accidents taking place in ponds. As children (< 5 years, esp. 1-4 year age group) are among the high risk groups for drowning, these groups should be the focus of preventive programs. In addition, as a health priority, the control and prevention of accidents in children should be considered by health professionals.

The superminimality of the fibres of an almost contact metric submersion is used to study the integrability of the horizontal distribution and the structure of the total space.

Kinetic and potential energies available in water dissipating using structures like drops can be used for generating electricity on small scale. To this aim, the Archimedes screw turbine, as an emerging turbine, can be employed for converting kinetic and potential energies to mechanical energy in irrigation canals. However, there is no literature in this regard. In this research, the effect of tailwater on turbine performance was investigated. To this end, an Archimedes screw turbine was designed and validated using FLOW-3D, and the effect of different submersion ratios was investigated. The results showed that there needs 0.5 to 0.75 submersion ratio in the downstream canal to avoid extra power loss, resulting in maximum power and efficiency in the same conditions.

Weir is a structure that is made in the body or support of the dam to safe drain the excess volume of water in the tank. Weirs are mainly considered for free flow mode, but in some cases there is a possibility of immersion in them. Submersion in weirs occurs in two general and local ways. General submersion will occur if the downstream water level is higher than the weir crown level. This is more likely to occur for weirs in canals and rivers and if the weir acts as a diversion dam. Local submersion is observed in the downstream part of weir due to local flow conditions. Weirs are divided into linear and non-linear weirs based on the shape in the plan. Piano key weirs are the newest type of non-linear weirs which recently due to its advantages. Non-linear Piano Key Weirs enjoy not only a higher water passage but also a relatively simple and economic structure compared to linear weirs. All experiments of this research were performed in a channel with a long 10 m, wide 0.75 m and high 0.8 m in Tarbiat Modares University hydraulic laboratory. A view of the laboratory flume is shown in Figure (3). The required water was supplied through an underground reservoir. In this research, trapezoidal piano key weir types A, made of thermoplastic with a thickness 1.2 m, slope of the input and output keys 28 degrees and a height 0.2 m was used. The weir has 6 keys (3 input keys and 3 output keys) with the same slope in the input key and the output key. Uniform bed materials with an average diameter 2.2 mm were used. Flow discharge was measured with an ultrasonic flowmeter and flow depth and bed level were measured with a laser level gauge. According to the selected discharges, the flow depth upstream of the weir was considered to be more than 3 cm so that the effect of surface tension is not significant. In this study, experiments were performed with five discharges 30, 40, 50, 60 and 70 liters per second. Under submerged flow for each discharge, two percent submersion and under free flow for each discharge, the tailwater depth was considered to be 0.13 m. Flow characteristics are affected in case of weir submersion. During the test, after the flow hit from the input switch to the tailwater surface, due to the amount of tailwater depth, surface rotations (at low tailwater depth) and surface turbulence (at high tailwater depth) are observed. Part of the flow moves downwards and after hitting the bed surface, a weak rotational zone is created in the range of the input switches. The flow enters the downstream in the form of a submerged jet after the output switch and, due to the momentum to the upper fluid, causes a severe rotational zone in the range of the output switches. In the free flow, more turbulence is observed in the range of the output switches due to the intersection of the flow passing through the weir lateral wall and the falling current from the upstream and downstream crowns. Less tailwater depth in free flow limits the deep growth and development of the sedimentary hill in downstream of the scouring hole, and sedimentation occurs with longer length and lower elevation. However under the submerged flow, due to the greater tailwater depth and lower fall height, the flow strength is more depleted and the flow strikes the bed with less energy, and result in less scouring. In this case, the flow does not have the power to transfer all the sediments to the downstream and most of the sediments accumulate on top of each other and a sedimentary hill is created as a point. As a result, a sedimentary hill with a higher height and less length is visible under submerged current than free flow. Therefore, in the free flow than in the submerged flow, the length and depth of the scour hole occur more, and sedimentation occurs with less height and longer length. Under submerged flow, most of the sediment bed remains unchanged, while under free flow most of the sediment bed is affected by scouring and sedimentation. Of course, changes vary depending on the hydraulic conditions. In the early times, in both free and submerged currents, scouring occurs with greater intensity, but over time, its severity decreases and scouring reaches a stable state. In this case, sediments are rarely transported downstream. The surface of the sedimentary hill downstream of the scour hole in the open stream is almost smooth and in the submerged stream is sharp. The results showed that most of the scour hole changes occur in 20% of the initial time of the experiment and the changes in the free flow are faster than the submerged flow. The depth and length of the scour hole in free flow is greater than in submerged flow. Relative scour depth with increasing 77% in tailwater depth for Froude numbers of particle 0.029, 0.037, 0.045, 0.052 and 0.058, respectively 42, 45, 21, 28 and 27% and with increasing the tailwater depth 123% is reduced by 95%, 92%, 90%, 75% and 68%, respectively. With increasing 18% in the submersion ratio in the Froude number of particle 0.029 and increasing 96% in the submersion ratio in the Froude number of particle 0.058, the maximum relative scour depth decreases by 92 and 56%, respectively. The location of the maximum scouring is also a function of Froude number of particle and the tailwater depth. Maximum scour depth at the tailwater depth 0.13 m at a distance 0.18 to 0.30 m from the weir toe, at the tailwater depth 0.23 m at a distance 0.18 to 0.36 m from the weir toe and at a tailwater depth 0.29 m is at a distance 0.03 to 0.30 m from the weir toe.

To determine if there is a difference in the quantity of microbial flora of the conjunctiva in individuals practicing head submersion (“dunk”) versus no head submersion(“no-dunk”) during hot tub use.

In this double-blind randomized clinical trial, healthy volunteers aged ≥ 18 years were recruited. Participants were randomized to head submersion versus no head submersion during a 15-minute hot tub soak. Study personnel,masked to the dunkor no-dunk group assignment,obtained conjunctival cultures before and immediately after hot tub use. De-identified specimens were submitted to the clinical microbiology laboratory for culture and analysis. The main outcome measure was the difference in the quantity of organisms cultured from the conjunctiva beforeand after hot tub exposure, as determined usinga defined ordinal scale.A two-tailed Student’s t-test was performed to compare the total microbial colony counts between the two arms. Simpson’s diversity was used to measure the changes in organism diversity between the arms.

Of 36 enrolled subjects, 19 were randomly assigned to thedunkand 17 were assigned to the no-dunk groups. Water samples obtained from all hot tubs wereculture negative. Eleven of 19 eyes (58%) from the dunkgroup and eight of 17 eyes (47%) from the no-dunkgroup had negative conjunctivalbacterial cultures before and after hot tub exposure. However, six of 19 eyes (32%) and four of 17 eyes (24%) of the dunkand no-dunkgroups, respectively, were culture-positiveafter,but not beforehot tub exposure. The quantity of organisms before and after hot tub exposure was notsignificantlydifferentbetween the two arms (P=0.12). However, the dunk grouponly showed a small increase in the quantity of organisms afterascompared to beforehot tub use(P=0.03). None of the samples from subjects or hot tubs were culture-positive for Acanthamoeba.

Head submersion in a public hot tubsduring a 15-minute soak does not appear to change conjunctival flora,as determinedby culture plate yield, this does not eliminate the association between hot tub use and devastating and painful corneal blindness. Therefore, our recommendation is to remove contact lenses prior to hot tub use, avoid head submersion in a hot tub, and urgently seek ophthalmological help if any eye pain and/or decrease in vision is experienced after hot tub use.

Vehicle submersion is an important cause of death in road traffic injury in Iran. Based on the data of the Iran’s National Registry of Drowning (INRD), a high number of drownings are related to road traffic accidents. In the United States, 11% of overall drownings and about 5% of drowning deaths are related to vehicle submersion. In this review, we tried to find some information about vehicle submersion as an unknown cause of death.

A review was done using PubMed, Scopus, Web of Science, Google Scholar, SID, and IranMedex. Articles related to vehicle submersion were downloaded and related information was noted.

There are no guidelines on how to rescue from a floated car in Iranian databases. However, there are some guidelines in English which have been revised totally in recent years. However, there are rare pieces of evidence to test the efficacy of these guidelines. The car submersion survival message contains 4 phrases: unbuckle the seatbelts, open or break the car window, remove the children and get out from the floated car. The depth of water is an importan t issue in car floating and if it is near 40 centimeters, the car will be floated in the water and if the depth is more than 40 centimeters it may turn turtle.

The mechanism of trauma in road vehicle submersion is mixed and might contain both injuries related to the road accident and drowning. New evidencesareneeded for health policymakers to develop rescue guidelines for escaping submerged vehicles. Evidences can also be used by engineers to make safe cars.

Let A be a symmetric positive definite (n)×(n) real matrix for n ≥ 1 and S ∈ Rn be a hypersurface. We are supposed to determine the tangent space TpS in an arbitrary point p ∈ S in the case that the whole space Rn admits the inner product with matrix A. Among other things, some maximum and minimum properties for the vector fields perpendicular to tangent spaces of hypersurfaces, the compatibility of the image or inverse image of a hypersurface and its tangent space under an embedding, an isometry, and a submersion are also pointed out.

The aim of this paper is to consider horizontally weakly conformal maps which have been studied in [P. Baird and J. C. Wood, Harmonic morphisms between Riemannian manifolds, London Mathematical Society Monographs. New Series, 29, The Clarendon Press, Oxford University Press, Oxford, 2003]. We first generalize the results of this book for Euclidean space with arbitrary Riemannian metrics and then we study totally umbilic and totally geodesic integral manifolds of the projection map, when regarded as conformal submersion between Euclidean spaces with arbitrary Riemannian metrics.