Yield response and nitrogen utilization efficiency by drip-irrigated potato

Two field experiments were conducted in the Jordan Valley to evaluate potato response to N fertigation. Nitrogen as ammonium sulphate was supplied through irrigation water (fertigation) at rates of 0, 35, 70 and 105 mg N l^-1. Soil N application treatment equivalent to the fertigation treatment of 70 mg N l^-1 was included. ¹⁵N labelled ammonium sulphate was used to evaluate the N recovery and utilization efficiency. Yield increased by the N rate. The soil N application gave higher yield than the zero N and lower than the fertigated treatments. The increase in yield was due to the increase in the size of the tubers. The specific gravity was the highest with the zero N. The index ratios of potato tubers were similar with all treatments. The N derived from fertilizers by both tubers and shoots, increased with the N rate regardless of the method of application. The soil application treatments had fertilizer utilization as high as the fertigation treatments and produced total tuber yield not significantly different from that obtained by the fertigation treatment with similar rate. This might be attributed to the poor fertilizer distribution in the root zone in the fine textured soil. The low value of the fertilizer utilization of the plant receiving the ¹⁵N in the preceding season suggested possibilities of rapid transformation and immobilization by the soil microorganisms.     

Autoscan shift: A new core-rock data integration technique to overcome the shortcomings of conventional regression

For integrating rock mechanical data from cores and well logs, a new, two-stage technique is presented. The first stage consists of a less known criterion for filtering spurious data (outliers). It was developed and applied in astrophysics by Chauvenet [Chauvenet, W., 1863. Theory and Use of Astronomical Instruments: Method of Least Squares, pp. 558–566] but not applied in the E&P industry. The second stage is a new calibration method devised by us. The new calibration method has a unique characteristic: it preserves the shape of the depth vs. parameter profile of well logs.The conventional calibration technique uses the well-known Least Squares-based regression technique. This usually results in some distortion of the shape of the log-based data profile. The distortion is more serious whenever the coefficient of correlation is low, and can entirely mask the true variability of the measured parameter as obtained from the well log. In addition, the presence of any spurious data in the core data itself can render the calibration process meaningless.Calibrating the continuous log-based parameters (e.g., rock-mechanical elastic moduli) with the help of a limited number of core-based data is a routine job in designing mud-weight window for a stable borehole, ensuring sand-free hydrocarbon production, and productivity enhancement by hydraulic fracturing. The proposed technique will help make more accurate designs of these important exploration and production operations.The proposed technique can be commercialized as an independent package or by embedding it in an existing petroleum engineering software package. A preliminary version has already been delivered to Saudi Aramco to help design hydraulic fracturing that is currently being performed in the Hawiya/Haradh Gas Initiative.     

Optimisation study of large‐scale enzymatic synthesis of oleyl oleate,a liquid wax ester,by response surface methodology

An optimisation study of the large‐scale enzymatic synthesis of a liquid wax ester from oleic acid and oleyl alcohol using Novozym 435 was carried out. Investigations were performed in batch mode with a stirred tank reactor (STR) with one multi‐bladed impeller. Response surface methodology (RSM) based on a five‐level, three‐variable central composite rotatable design (CCRD) was used to evaluate the interactive effects of various parameters. The parameters are amount of enzyme (A) (90–120 g), impeller speed (B) (100–400 rpm) and temperature (C) (40–60 °C). The optimum conditions derived via RSM at a fixed reaction time of 1 h were successfully optimised as A = 104 g, B = 388.0 rpm and C = 49.7 °C. The actual experimental yield was 96.7% under the optimum conditions, which compared well with the maximum predicted value of 97.6%. Copyright © 2005 Society of Chemical Industry     

Ion-exchange kinetics and electrical conductivity studies of polyaniline Sn(IV) tungstoarsenate; (SnO2)(WO3)(As2O5)4(C6H5NH)2·nH2O: a new semi-crystalline ‘polymeric-inorganic’ composite cation-exchange material

A new and novel electrically conducting ‘polymeric-inorganic’ composite cation-exchange material; polyaniline Sn(IV) tungstoarsenate was prepared by incorporating polyaniline into inorganic ion-exchanger material. It possessed improved ion-exchange capacity, high chemical and thermal stabilities, reproducibility and selectivity for some specific metal ions. Kinetic study of exchange for some divalent metal ions of alkaline earths and transition metals was carried out under the conditions favoring a particle diffusion-controlled ion-exchange phenomenon and some physical parameters such as self diffusion coefficient D₀, energy of activation E_a and entropy of activation ΔS* were determined. The temperature dependence of electrical conductivity of this composite material with increasing temperatures was measured by using 4-in-line-probe DC electrical conductivity measuring-technique. The conductivity values lie in the semiconductor region, i.e. in the range of 10⁻³ S cm⁻¹ that follow the Arrhenius equation. The energy of activation of electrical conduction for the composite was also calculated.     

A non-stationary stochastic model for periodic excitation with random phase modulation

The paper presents a non-stationary stochastic model for periodic excitation with random phase modulation, where the phase modulation is modeled as a modulated stationary. Gaussian process. Applications of the model are demonstrated by analysis of response of a single-degree-of-freedom (SDOF) system under such an excitation. The response is, in general, non-Gaussian. Cases of step, rectangular, and exponential envelopes are considered in the present study. The nonstationary second and fourth order moments are calculated by numerically solving the transient moment equations. Non-Gaussianity of the response is studied in terms of the non-stationary excess factor. Some numerical results are presented. The influences of system parameters, build-up and decay rates as well as duration of random phase modulation on the moment response of the SDOF system are discussed.     

The Einstein relation for degenerate semiconductors with nonuniformband structures

Modification of the Einstein equation for semiconductors with nonparabolic energy bands and doped nonuniformly with impurity atoms is suggested. The suggestion is based on a new approximation of the Fermi-Dirac integral of order 1/2, namely, F_1/2(η_n), where η_n is the reduced Fermi level for electrons. The relation reduces to that for semiconductors with parabolic energy bands and doped uniformly with impurity atoms under appropriate boundary conditions. A comparison of the calculated and exact results for F_1/2(η) is found to be very encouraging     

Fractal model to predict the crack roughness effect on the local bending compliance of circular shafts

In this paper the local compliance due to a transverse fractal crack in a shaft under pure bending is investigated. In a fractal crack, the surface is considered irregular and it is characterized by the presence of nonuniformities at different scales. Therefore, the crack surface can be modeled as a fractal surface with fractal dimension D. An analytical model for the compliance coefficient is presented with and without the effect of the surface roughness. The results obtained shows that as the dimension of the fractal surface increases the compliance increases as well. It is shown that this behavior conforms well with existing experimental results.     

Grid computing: a STOPE view

Grid computing is emerging as the foundation upon which virtual organizations can be built. Such organizations are becoming of increasing importance for tackling various projects, both in academic and in business fields. This paper is concerned with presenting an integrated view of the grid to readers interested in understanding it, or perhaps in developing it further or making use of it in the future. The target view is based on the STOPE (strategy/technology/organization/people/environment) framework that has previously been used to integrate the issues of various information technology problems over its well‐defined domains. For strategy, the view considers the reasons associated with the need for the grid, including grid services and grid benefits. For technology, the technical components of the grid and their functions are taken into account. For organization, the organizations concerned with the development, technology production, service provisioning and use of the grid are considered. For people, those associated with the grid in the related organizations are taken into account. For the environment, rules, practices and support associated with the grid are discussed. Finally, the paper emphasizes questions that need to be answered in order to contribute to the future development of the grid. Copyright © 2006 John Wiley & Sons, Ltd.     

Tables of a Truncated Standard Normal Distribution: A Doubly Truncated Case

As an extension to the singly truncated case, this article further examines a doubly truncated normal distribution. In this article, we consider both symmetric and asymmetric cases with two truncation points on the left and the right, and develop the tables of a truncated mean, a truncated variance, and a cumulative probability.     

Novel Route to Propylene Carbonate: Selective Synthesis from Propylene Glycol and Carbon Dioxide

High surface area zirconium phosphate in an amorphous phase exhibits high activities for water-related reactions such as hydrolysis of ethyl acetate and esterification of acetic acid with ethanol. The zirconium phosphate is insoluble during the reaction, is recoverable by simple filtration, and can be reused at least five times without any treatment.