Friction Parameters for Flows in Nearly Flat Tidal Channels

A numerical study of friction parameters associated with nearly flat tidal channels is reported. Such empirical parameters are often back-calculated using complex flow equations through a procedure referred to as “inverse problems.” However, estimates of friction parameters of tidal channels are liable to substantial uncertainties if water levels are used in their inverse problems. Even if the parameters are optimized by mathematically comparing gauged and simulated values, the inverse problem must satisfy the quality conditions of “uniqueness,” “identifiability,” and “stability.” To obtain an insight into the problem, this paper focuses on flows where these conditions may not hold. The study concludes that friction parameters can be unidentifiable if the inverse problem employs gauged high tide water levels, because the effect of storage on water level dominates over friction. Gauged discharge values render identifiable, stable, and unique estimates of friction parameters even at high tides, but this is not a practical proposition. Low tide levels should be used to determine friction parameters, as the use of high-tide water levels can make friction parameters, and subsequently simulated discharge values, anomalous.     

Comparison of component method with experimental tests for flush end-plate connections using hot-rolled perwaja steel sections

A component method has been introduced by Steel Construction Institute to predict the moment resistance of partial strength connection. The design philosophy is taken directly from Eurocode 3 with strength checks on bolts, welds, and steel which have been modified to comply with BS 5950-1:2000. The accuracy of the method however needs to be validated with the experimental tests especially for hot-rolled sections other than typical British Section (BS). Six experimental tests on beam-to-column connections have been carried out for Flush End-Plate (FEP) connections consisting of variable parameters such as thickness of end-plate, size and number of bolts, size of columns, and beams. The tests were set-up using local hot-rolled steel sections known as Perwaja Section (PS) for beams and columns instead of typical British Section (BS). The strength of materials for end-plate, column and beam sections were tested for tensile strength and used in predicting the moment resistance for component method. The moment versus rotation of the test results were plotted and compared with the moment resistance derived from component method. The study concluded that the moment resistance of the tested flush end-plate connections was higher than the predicted moment resistance from component method which showed good agreement between the two moments. The study also concluded that the tested FEP connections met the requirements and criteria of partial strength connections.     

Thermodynamic behaviour of an air-conditioning system employing combined evaporative-water and air coolers

The performance of an open absorption-system, energized by low-grade heat such as insolation and/or waste heat, has been investigated. This combined evaporative cooler (CEC) [i.e. an indirect evaporative cooler (IEC) together with a direct evaporative-cooler (DEC)] was used to cool the air. A computer simulation of the cooling cycle was devised, so that the performance characteristics of the system could be predicted for a range of operating conditions: the influences of various design-parameters on the coefficient of performance (COP) were also evaluated. The COP of the CEC system was at least 20% greater than those achieved when employing either the IEC or DEC systems alone.     

A Hybrid Model to Predict Monthly Streamflow Using Neighboring Rivers Annual Flows

Water Resources Management - The issue of predicting monthly streamflow data is an important issue in water resources engineering. In this paper, a hybrid model was proposed to generate monthly...     

Nitrogen-Doped Porous Nickel Molybdenum Phosphide Sheets for Efficient Seawater Splitting

Hydrogen is emerging as an alternative clean fuel; however, its dependency on freshwater will be a threat to a sustainable environment. Seawater, an unlimited source, can be an alternative, but its salt-rich nature causes corrosion and introduces several competing reactions, hindering its use. To overcome these, a unique catalyst composed of porous sheets of nitrogen-doped NiMo₃P (N-NiMo₃P) having a sheet size of several microns is designed. The presence of large homogenous pores in the basal plane of these sheets makes them catalytically more active and ensures faster mass transfer. The introduction of N and Ni into MoP significantly tunes the electronic density of Mo, surface chemistry, and metal-non-metal bond lengths, optimizing surface energies, creating new active sites, and increasing electrical conductivity. The presence of metal-nitrogen bonds and surface polyanions increases the stability and improves anti-corrosive properties against chlorine chemistry. Ultimately, the N-NiMo₃P sheets show remarkable performance as it only requires overpotentials of 23 and 35 mV for hydrogen evolution reaction, and it catalyzes full water splitting at 1.52 and 1.55 V to achieve 10 mA cm⁻² in 1 m KOH and seawater, respectively. Hence, structural and compositional control can make catalysts effective in realizing low-cost hydrogen directly from seawater.     

Comparison of Methods for Colorimetric Amylose Determination in Cereal Grains

Iodine‐based colorimetry remains the most widespread method for the determination of amylose content of starch. There are, however, many variants of this method, differing in solvent, temperature and method for converting absorbance to amylose content. Therefore, in thisstudy some of these methods were compared in order to identify which, if any, was most reliable. Australian commercial samples of wheat, rice, rye and oat were used. Flour was ground and starch was extracted. Half of the samples of flour and starch were defatted with n‐propanol. Defatted and full‐fat flours and starches were dissolved by six procedures: DMSO, urea‐DMSO, CaCl₂‐DMSO, hot NaOH, cold NaOH and HCl. The solutions were diluted, coloured with iodine and the absorbances determined at 535 and 620 nm. Amylose content was determined by reference to standards using 620 nm as the single wavelength or by two calculations based on the ratio between the two absorbances. Reliability was tested by repeating all tests on three non‐consecutive days with three replicates on each day. Defatted starch provided more consistent results than flour or non‐defatted starch. The most reliable dissolution procedure, with both the lowest standard error and least day‐to‐day variation, was cold NaOH. One of the ratio‐based calculations provided adequate correction for the non‐starch content of flour of wheat and rice, but not of the other two cereals, and the other ratio‐based calculation seldom provided realistic results. It is concluded that a cold NaOH dissolution procedure is suitable for reliable amylose determination on defatted starch of a range of cereals from a single wavelength and that it is also suitable for use on defatted flour of some species.     

Generalized linear model based monitoring methods for high-yield processes

Emerge in technology brought well-organized manufacturing systems to produce high-quality items. Therefore, monitoring and control of products have become a challenging task for quality inspectors. From these highly efficient processes, produced items are mostly zero-defect and modeled based on zero-inflated distributions. The zero-inflated Poisson (ZIP) and zero-inflated Negative Binomial (ZINB) distributions are the most common distributions, used to model the high-yield and rare health-related processes. Therefore, data-based control charts under ZIP and ZINB distributions (i.e., Y-ZIP and Y-ZINB) are proposed for the monitoring of high-quality processes. Usually, with the defect counts, few covariates are also measured in the process, and the generalized linear model based on the ZIP and ZINB distributions are used to estimate their parameters. In this study, we have designed monitoring structures (i.e., PR-ZIP and PR-ZINB) based on the ZIP and ZINB regression models which will provide the monitoring of defect counts by accounting the single covariate. Further, proposed model-based charts are compared with the existing data-based charts. The simulation study is designed to access the performance of monitoring methods in terms of run length properties and a case study on the number of flight delays between Atlanta and Orlando during 2012–2014 is also provided to highlight the importance of the stated research.     

A Novel Optical Technique Based on Image Processing for Determination of Tokamak Plasma Displacement

Plasma displacement is one of the main problems of tokamak plasma equilibrium. Control of plasma displacement has important role in plasma confinement and to achieve optimized tokamak plasma operation. In this contribution we presented a navel and simple optical technique for determination of tokamak plasma column displacement. For this purpose, an image processing technique used for the output signal of CCD camera and then plasma emission intensity profile and plasma position obtained.     

Application of the MOSFET device structure in characterizing imperfection centers in indium-doped silicon

C.T. Sah has published a review article demonstrating the application of high-frequency small signal capacitance and current transients of a space charge layer. Application of such transients is a powerful technique in characterizing deep level imperfection center concentrations, energy levels, thermal and optical emission rates and thermal capture cross sections. The MOSFET device structure is particularly convenient for low temperature measurements of shallow levels where deionization occurs and the substrate becomes highly resistive, seriously limiting capacitance transient techniques. Examples are given by results on indium-doped silicon, such as employed in extrinsic IR detectors. The emission time constant of holes from the neutral indium center has been found to depend on the indium doping. Measurements on lightly doped samples yield a value for the emission rate, $\text{1}\text{e}{}_{\mathrm{p}}$, of 6.0 msec at 77°K and a thermal activation energy of 0.15 eV. Measurements on heavily doped samples yield values of $\text{1}\text{e}{}_{\mathrm{p}}$ of 20 μsec at 77°K and an activation energy of 0.117 eV. These results are consistent with the Poole-Frenkel effect describing field enhanced thermal emission of holes from the indium center. Measurements of the hole capture coefficient at 77°K yield values for c_p of 3.7 × 10^?7 cm³/sec. These measurements have been made on heavily doped samples. The capture coefficient measured is the zero field or quasi-equilibrium value. The temperature dependence of the hole capture coefficient has been found to be T^?4. Small transients in the thermal emission rate measurements have been observed. These transients have thermal activation energies of around 0.08 eV and are associated with the 0.11 eV level as reported by Hughes Research Labs after accounting for barrier lowering by the Poole-Frenkel effect.     

Performance Parameters of ATM Networks with Bursts of Errors

In this paper we present the calculation of the error performance of a point-to-point ATM connection transported on an STS-3c SONET (SDH STM-1) interface. The ATM layer performance parameters calculated are Cell Loss Ratio (CLR), Cell Error Ratio (CER), and Severely Errored Cell Block Ratio (SECBR). Statistics of consecutive errored and lost cells are also calculated for each run of the simulation. The physical layer performance parameters such as Bit Error Ratio (BER), Errored Second Ratio (ESR), and Severely Errored Second Ratio (SESR) are compared with corresponding objective values in G.826. The bursty nature of errors in physical communication channels is described by the Hidden Markov Model (HMM) which is obtained from the experimental data. The importance of using this model is demonstrated by the simulation results. The ATM performance for channels with independent errors differs significantly from the ATM performance for channels with bursts of errors and equal bit error ratios.