Optimizing Approach of Water Allocation to Off-Takes During Reduced Flows

Multi-objective optimization models with an index were developed based on farmers’ preferences, local requirements, supplies available at the head of the canal, system losses, crop demand about different growth stages, and field soil moisture balance. The models were applied using linear programming. The Model 1 determines the cropping pattern by maximizing net economic benefits using a monthly basis lumped volume available at the head of the canal and is set to the minimum and maximum area constraints along with the constraint of minimum main crop area. The areas for different crops given by the first model form input for the Model 2. The other inputs of Model 2 included periodic supply available at the head of the primary canal (7-day period in this study), root growth depth, demand, and soil moisture constants. The Model 2 optimizes the sum of relative yields of all the crops and provide the irrigation levels of various crops for specified periods. Finally, the distributed area and irrigation levels determined by Model 2 are used in conjunction with the losses to decide flow rates of off takes. The complete program was implemented in the West branch irrigated area of Mirpurkhas subdivision. The results showed that the resources were allocated to off-takes in a competitive and conflict-free manner.

     

Gamma-ray shielding properties of zinc oxide soda lime silica glasses

In the present work, the gamma ray shielding properties of zinc oxide soda lime silica, (ZnO)_x(SLS)_1?x glasses with 0 ≥ x ≥ 50 wt% have been investigated. By using WinXCom computer software, the mass attenuation coefficient (µ/ρ) and half value layer (HVL) for total photon interaction in the energy range of 1 keV–100 GeV were calculated. Furthermore and by Geometric Progression method exposure buildup factor values were calculated for incident photon energy 0.015–15 MeV up to penetration depths of 40 mfp (mean free path). The addition of zinc oxide (ZnO) into soda lime silica (SLS) glass resulted in an increase the mass attenuation coefficient and decreases both the half value layer and exposure buildup factor. The obtained results of the selected glass series have been compared, in terms of mass attenuation coefficient, half value layer and exposure buildup factor with some common shielding materials. The shielding effectiveness of the selected glasses is found comparable to that of common ones; which indicates that the SLS glasses with suitable ZnO content may be developed as gamma ray shielding materials.     

Oxidative dehydrogenation of isobutane over pyrophosphates catalytic systems

The catalytic effect of metal pyrophosphates (i.e., Mn₂P₂O₇, Ni₂P₂O₇, CeP₂O₇, Mg₂P₂O₇, ZrP₂O₇, Ba₂P₂O₇, V₄(P₂O₇)₃ and Cr₄(P₂O₇)₃) on the oxidative dehydrogenation of isobutane to isobutene in the reaction temperature range of 400–600 °C has been investigated. CeP₂O₇ gives the highest isobutene yield and selectivity (71%), however, V₄(P₂O₇)₃ is the most active catalyst with an isobutane conversion of 33.5% at 500 °C. Increasing the reaction temperature results in higher isobutane conversions and lower isobutene selectivity. Reaction by-products are propylene, CO, CO₂ and traces of methane and ethylene. No oxygenate products are formed under the used reaction conditions. The sum of selectivities of CO, CO₂ and methane is approximately equal to that of propylene, indicating their formation from total oxidation of C₁ species accompanying the isobutane crack reactions. Working at temperatures higher than 550 °C, the homogeneous gas phase reactions become significant and the oxygen conversion reaches 100%. This revised version was published online in July 2006 with corrections to the Cover Date.     

Multidimensional modeling of a microfibrous entrapped cobalt catalyst Fischer‐Tropsch reactor bed

Thermal management of highly exothermic Fischer‐Tropsch synthesis (FTS) has been a challenging bottleneck limiting the radial dimension of the packed‐bed (PB) reactor tube to 1.5 in. ID. A computational demonstration of a novel microfibrous entrapped cobalt catalyst (MFECC) in mitigating hot spot formation has been evaluated. Specifically, a two‐dimensional (2‐D) model was developed in COMSOL^®, validated with experimental data and subsequently employed to demonstrate scale‐up of the FTS bed from 0.59 to 4 in. ID. Significant hot spot of 102.39 K in PB was reduced to 9.4 K in MFECC bed under gas phase at 528.15 K and 2 MPa. Improvement in heat transfer within the MFECC bed facilitates higher productivities at low space velocities (≥1000 h^?1) corresponding to high CO conversion (≥90%). Additionally, the MFECC reactor provides an eightfold increase in the reactor ID at hot spots ≤ 30 K with CO% conversions ≥ 90%. This model was developed for a typical FTS cobalt‐based catalyst where CO₂ production is negligible. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1723–1731, 2018     

Simulation, integration, and economic analysis of gas-to-liquid processes

Gas-to-liquid (GTL) involves the chemical conversion of natural gas into synthetic crude that can be upgraded and separated into different useful hydrocarbon fractions including liquid transportation fuels. Such technology can also be used to convert other abundant natural resources such as coal and biomass to fuels and value added chemicals (referred to as coal-to-liquid (CTL) and biomass-to-liquid (BTL)). A leading GTL technology is the Fischer-Tropsch (FT) process. The objective of this work is to provide a techno-economic analysis of the GTL process and to identify optimization and integration opportunities for cost saving and reduction of energy usage while accounting for the environmental impact. First, a base-case flowsheet is synthesized to include the key processing steps of the plant. Then, a computer-aided process simulation is carried out to determine the key mass and energy flows, performance criteria, and equipment specifications. Next, energy and mass integration studies are performed to address the following items: (a) heating and cooling utilities, (b) combined heat and power (process cogeneration), (c) management of process water, (c) optimization of tail gas allocation, and (d) recovery of catalyst-supporting hydrocarbon solvents. Finally, these integration studies are conducted and the results are documented in terms of conserving energy and mass resources as well as providing economic impact. Finally, an economic analysis is undertaken to determine the plant capacity needed to achieve the break-even point and to estimate the return on investment for the base-case study.     

Innovative Hetero-Associative Memory Encoder (HAMTE) for Palmprint Template Protection

Many types of research focus on utilizing Palmprint recognition in user identification and authentication. The Palmprint is one of biometric authentication (something you are) invariable during a person’s life and needs careful protection during enrollment into different biometric authentication systems. Accuracy and irreversibility are critical requirements for securing the Palmprint template during enrollment and verification. This paper proposes an innovative HAMTE neural network model that contains Hetero-Associative Memory for Palmprint template translation and projection using matrix multiplication and dot product multiplication. A HAMTE-Siamese network is constructed, which accepts two Palmprint templates and predicts whether these two templates belong to the same user or different users. The HAMTE is generated for each user during the enrollment phase, which is responsible for generating a secure template for the enrolled user. The proposed network secures the person’s Palmprint template by translating it into an irreversible template (different features space). It can be stored safely in a trusted/untrusted third-party authentication system that protects the original person’s template from being stolen. Experimental results are conducted on the CASIA database, where the proposed network achieved accuracy close to the original accuracy for the unprotected Palmprint templates. The recognition accuracy deviated by around 3%, and the equal error rate (EER) by approximately 0.02 compared to the original data, with appropriate performance (approximately 13 ms) while preserving the irreversibility property of the secure template. Moreover, the brute-force attack has been analyzed under the new Palmprint protection scheme.     

A property-integration approach to solvent screening and conceptual design of solvent-extraction systems for recycling used lubricating oils

The significant quantities of used and discharged lubricating oils pose a major environmental problem around the world. Recently, there has been a growing interest in the sustainable usage of lubricating oils by adopting recovery, recycle, and reuse strategies. In this study, a property-integration framework is used in the optimization of solvent selection for re-refining of used lubricating oils. Property-integration tools are employed for the systematic screening of solvents and solvent blends. The proposed approach identifies the main physical properties that influence the performance of solvent(s) while extracting additives and contaminants from used lubricating oils (i.e., solubility parameter (δ), viscosity (v), and vapor pressure (p)). To identify a feasibility region for an effective solvent or solvent blend for this process, we construct a ternary diagram utilizing the property-clustering technique. The results of the theoretical approach are validated through comparison between experimental data for single solvents and for solvent blends.     

Expanded roles for the MutL family of DNA mismatch repair proteins

The MutL family of DNA mismatch repair proteins plays a critical role in excising and repairing misincorporation errors during DNA replication. In many eukaryotes, members of this family have evolved to modulate and resolve recombination intermediates into crossovers during meiosis. In these organisms, such functions promote the accurate segregation of chromosomes during the meiosis I division. What alterations occurred in MutL homolog (MLH) family members that enabled them to acquire these new roles? In this review, we present evidence that the yeast Mlh1–Mlh3 and Mlh1–Mlh2 complexes have evolved novel enzymatic and nonenzymatic activities and protein–protein interactions that are critical for their meiotic functions. Curiously, even with these changes, these complexes retain backup and accessory roles in DNA mismatch repair during vegetative growth.     

A Gas Chromatographic Method with Electron-Capture Detector (GC-ECD) for Simultaneous Determination of Fenpropathrin, λ-Cyhalothrin, and Deltamethrin Residues in Tomato and Its Applications to Kinetic Studies After Field Treatment

In this study, simultaneous determination of fenpropathrin, ??-cyhalothrin, and deltamethrin in tomato fruit (Lycopesicon esculentum) grown in Khartoum, Sudan, was carried out using gas chromatography with electron capture detector (GC-ECD).The method was linear in the range of 0.001?C0.01, 0.001?C0.01 and 0.001?C0.02?mg/ml for fenpropathrin, ??-cyhalothrin, and deltamethrin, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.0012 and 0.0041, 0.0013 and 0.0041 and 0.0026 and 0.0087?mg/ml for fenpropathrin, ??-cyhalothrin, and deltamethrin, respectively. The recoveries of fenpropathrin, ??-cyhalothrin, and deltamethrin at three concentration levels spiked to tomato were found to be in range 85.77?±?1.52?C95.61?±?3.65%, 91.77?±?4.34?C98.59?±?2.46% and 92.61?±?2.46?C98.04?±?2.93%, respectively. The kinetic study of the degradation of all pesticides was performed and the ultimate evaluation of the kinetic data revealed a pseudo first order kinetics pattern for fenpropathrin, ??-cyhalothrin, and deltamethrin.