Determining anti-plane responses induced by oblique-truncated semicircular canyon using systematic hybrid method with mapping function

This paper proposes a novel strategy for the investigation of displacement amplitude ($\left|u_y\right|$) near and along an oblique-truncated semicircular canyon subjected to shear horizontal (SH) waves. Transfinite interpolation (TFI) was used to obtain the coordinates of nodes and determine the sequence of node numbering in the inner finite region including the canyon. The hybrid method, comprising finite element method and a Lamb series, was applied in conjunction with TFI to study the effects of canyon geometry, incident angle of SH waves ($\theta$), and dimensionless frequency ($\eta$) on $\left|u_y\right|$. We detailed the amplification of $\left|u_y\right|$ in the illuminated zone and variations in $\left|u_y\right|$ due to canyon-decay-effect along the canyon surface as well as the decay of $\left|u_y\right|$ resulting from the shield effect in the shadow zone. Interestingly, oblique-effects play an important role in the magnification of $\left|u_y\right|$ along the inclined bottom of canyons, and variations in $\theta$ and $\eta$ dominate the patterns of $\left|u_y\right|$.     

The ratio of measured to total sediment discharge

It is important to examine the ratio of measured to total sediment discharge to determine the error in measured sediment transport rates from depth-integrated samplers. The ratio of measured to total sediment discharge as well as the ratio of suspended to total sediment discharge are examined based on the Modified Einstein Procedure. Both ratios reduce to a function of the ratio of shear velocity, $u_{*}$, to the fall velocity, $\omega$, of suspended material, $u_{*}/\omega$, and the ratio, $h/d_s$, of flow depth, h, to the median grain size of bed material, $d_{50}$. In rivers transporting fine material (such as silt or clay), the ratio of suspended to total load is a function of the ratio, $h/d_{50}$. In this study, it is found that the ratio of measured to total load becomes a simple function of flow depth. For fine sediment transport, with a Rouse number (Ro) $<0.3$, at least 80% of sediment load is in suspension when $h/d_{50}>15$, and at least 90% of sediment load is measured from depth integrating samples when $h>1\mathrm{m}$. Detailed measurements from 35 river stations in South Korea demonstrate that sand sizes and finer fractions predominantly are transported in suspension. Also, at least 90% of sand and finer fractions are transported in suspension in gravel and sand bed rivers when the discharge is larger than the mean annual discharge.     

The isotope composition of evaporating brines: Effect of the isotopic activity ratio in saline solutions

The ratio of the activity coefficients of deuterated and light water (Γ) is given in chloridic saline solutions as a function of the molality of the salt components by the expression: $\left(1?\frac{1}{\Gamma }\right)x{10}^3\equiv ?\Delta \delta =6.1M_{CaC{l}_2}+5.1M_{MgC{l}_2}+2.4M_{KCl}+0.4M_{NaCl}$Calculations based on the Craig-Gordon evaporation model show that in the case of evaporating brines, the salt effect on the activity coefficients of the isotopic water species results in deviation of the δ values from a constant slope “evaporation line”, when plotted on the conventional δ-diagram, of deuterium concentration versus ¹⁸O activity. Conversion of concentration data to activities eliminates these deviations to a large extent, indicating them to be an artifact of the scales employed for measuring the isotope abundance. The origin of Dead Sea waters and other natural brines is discussed in the light of these findings.     

Measurements of total carbon dioxide and alkalinity by potentiometric titration in the GEOSECS program

Approximately 6000 determinations of the alkalinity and total carbon dioxide content of seawater have now been made in the Atlantic, Pacific and Indian Oceans as part of the GEOSECS program by a computer-controlled potentiometric titration technique. The equations used to locate the equivalence points of the carbonic acid system on this titration curve were developed in 1971 but have not previously been published. These functions may be represented by:$\begin{array}{l}{F}_1=\frac{\left(V_2?V\right)}{V_0}N\left[H^{+}\right]/K_{1C}+\frac{\left(V_0+V\right)}{V_0}\left(\left[H^{+}\right]+\left[HS{O}_4^{?}\right]+\left[HF\right]?\left[B{\left(OH\right)}_4^{?}\right]\right)\\ \times \left(1+\left[H^{+}\right]/K_{1C}\right)\\ F_2=\frac{\left(V_0+V\right)}{V_0}\left(\left[H^{+}\right]+\left[HS{O}_4^{?}\right]+\left[HF\right]?\left[HC{O}_3^{?}\right]\right)\end{array}$Upon inspection, these functions are analogous to the modified Gran functions of Hansson and Jagner [25] with the omission of the contributions of [OH^?] and [CO₃^2?], and with the contribution of B(OH)₄^? being assessed at a chlorinity of 19‰ for all samples. Reprocessing the original titration e.m.f.-volume data with appropriate corrections and modified Gran functions reveals an error of about +12 μmol/kg in the GEOSECS total carbon dioxide data. In addition, the protonation of dissolved phosphate species during the titration results in a contribution to measured total carbon dioxide equal to the total phosphate concentration. Differences in the application of the GEOSECS functions between the Atlantic and the Pacific-Indian Oceans expeditions are also to be found so that the error deriving from this source for the Atlantic expedition was only +5 μmol/kg. The application of the correct functions increases precision enabling smaller differences, such as those attributable to fossil fuel carbon dioxide, potentially to be observed, and increases accuracy so that the error in titrator total carbon dioxide previously diagnosed by Takahashi [14] can be logically accounted for.     

Experimental study on the effect of bottomless structure in front of a bottom outlet on a sediment flushing cone

One of the main problems in reservoirs is sedimentation which reduces the operating life of dams if a proper plan and analysis method are not in place.The techniques to manage sediment in reservoirs include several sustainable management techniques that route sediment through or around the reservoir.One of the main economical methods in arid and semi-arid regions is pressurized flushing using moderate drawdown of the water level of the reservoir to evacuate sediment deposited behind dams.In the current study,the effect of a new structure called a dendritic bottomless extended(DBE)outlet structure at three angles of 30°,45°,and 60°
on pressurized flushing efficiency was investigated.Consequently,45 experiments were designed for three discharge rates (Qo),three sediment levels(Hs),four types of structure,and a no-structure condition(reference test).The results indicated that the DBE structure with a 30°angle between the branches,a sedimentary dimensionless index of Hs/Do=4.59,and a flow dimensionless index of Qo=/√gD05=1:43(where g is the acceleration of gravity and Do is the diameter of the bottom outlet)lead to 10-fold increase in the sediment flushing cone dimensions and sediment removal efficiency compared to the results of the reference test.Finally,according to a statistical analysis of the results,a dimensionless equation for calculating the sediment flushing cone dimensions was developed for the tested sediment characteristics.