Optimal actuation of nonlinear resonant systems

In this study, we examine a new approach for actuation of dynamical systems with minimum work and maximum amplitude while maintaining constraints on the actuation force. Two methodology issues are addressed in the paper: sensitivity analysis about the nonlinear transient response and exploration of the strongly nonlinear relationship between the two objectives and the actuation design variables. The optimization analysis is carried out on lightly damped Duffing systems. The formulation of the optimization problem is found ideally suited to resolve the difficulty of dependence of response on initial conditions. The tradeoff curve of work and amplitude is computed. The optimal actuation strove to compensate for the limited force amplitude by an abrupt change in the force in time. Finally the optimization procedure is demonstrated on the kinematic design of hovering insect flight. The optimal design gives 50% reduction in power consumption, with a larger cutback for an actuation with high acceleration.     

Pd-doped Co nanofibers immobilized on a chemically stable metallic bipolar plate as novel strategy for direct formic acid fuel cells

High contact resistance and corrosion are the main dilemma facing wide application of the metallic bipolar plates. In this study, deposition of thin film from Pd-decorated Co nanofibers on a silicon substrate is introduced as a novel strategy to produce functionalized metallic bipolar plate. The novel active metallic bipolar plate can be prepared by using simple, low cost, high yield and effective technique; electrospinning. The bimetallic nanofibrous film chemically bonds with the silicon substrate due to formation of silicon carbide which leads to merge the deeper nanofibers with the silicon surface. Accordingly, high current density (100 mA cm⁻¹) was obtained when the introduced covered silicon wafer was utilized as anode catalyst for formic acid electrooxidation. Because the bimetallic nanofibers are sheathed in a thin graphite shell, the introduced active bipolar plate reveals very good stability. Overall, the introduced study is opening a new avenue to prepare new class of functionalized metallic bipolar plates.     

Development and Use of Quantitative Competitive PCR Assay for Detection of Poultry DNA in Sausage

This study focused on the development and evaluation of a quantitative competitive polymerase chain reaction (QC-PCR) for detection and quantification of poultry DNA in sausage. PCR is well known to be quantitative if internal DNA standards are co-amplified together with the target DNA. A DNA competitor differing by 83 bp in length from the poultry target sequence was constructed and used for PCR together with the target DNA. Specificity of the new primers was evaluated with DNA from cattle and sheep. The results of QC-PCR showed that the percentage of contamination was in the range of 23.87–52.06%.     

Effect of roasting on colour and volatile composition of pistachios (Pistacia vera L.)

Pistachios have been roasted following the Iranian traditional method (soaking in salty water, drying and roasting at 135 °C). Three Iranian pistachio cultivars (Ahmad Aghaei, Akbari and Kaleghouchi) were compared for their volatile compositions, colour and odour intensity. Lightness decreased in the course of roasting, which resulted from Maillard reaction. Raw pistachios had lower concentrations of most volatiles than roasted. A total of twenty‐six compounds were detected in roasted pistachios; these included aldehydes, terpenes, alcohols and only two pyrazines and one furan. These mixtures of volatiles implied that the Iranian roasting system is very soft, and samples retained most of the vegetable notes from fresh pistachios and some roasted notes were generated as well (from 2‐ethyl‐5‐methylpyrazine and 2,6‐dimethyl‐3‐ethylpyrazine). Sample from cultivar Akbari presented higher odour intensity than those by the other two cultivars, due mainly to higher concentrations of pyrazines developed during the roasting step.     

Oil revenue shocks and government spending behavior in Iran

Oil revenues play an important role in the political economy of Iran. On average, 60% of the Iranian government revenues and 90% of export revenues originate from oil and gas resources. Current international sanctions on Iran have mainly targeted the oil production capacity of Iran and its exports to the global markets. In this study, we analyze the dynamic effects of oil shocks on different categories of the Iranian government expenditures from 1959 to 2007, using impulse response functions (IRF) and variance decomposition analysis (VDC) techniques. The main results show that Iran's military and security expenditures significantly respond to a shock in oil revenues (or oil prices), while social spending components do not show significant reactions to such shocks.     

The joint reaction of methanol and i-butane over the HZSM-5 zeolite

The effects of i-butane addition to methanol in MTP reaction were investigated over an in-house prepared HZSM-5 catalyst. It was observed that, propylene yield would be enhanced when i-butane fed to the reactor along with methanol. The rising growth of the propylene yield continued to peak on till the balance in thermal condition established. Similar trends have been observed when water was added to the mixture. The effect of WHSV with fixed water composition on product distribution was also studied. The optimum point where the highest amount of propylene yielded was shown to be high depended upon the temperature and residence time.     

Mathematical modeling of a multi-stage naphtha reforming process using novel thermally coupled recuperative reactors to enhance aromatic production

In this study, a novel thermally coupled reactor containing the naphtha reforming process in the endothermic side and the hydrogenation of nitrobenzene to aniline in the exothermic side has been investigated. Considering the higher thermal efficiency as well as the smaller size of the reactor, utilizing the recuperative coupled reactor is given priority. In this novel configuration, the first and the second reactor of the conventional naphtha reforming process have been substituted by the recuperative coupled reactors which contain the naphtha reforming reactions in the shell side, and the hydrogenation reaction in the tube side. The achieved results of this simulation have been compared with the results of the conventional fixed-bed naphtha reforming reactors. Acceptable enhancement can be noticed in the performance of the reactors. The production rate of the high octane aromatics and the consumption rate of the paraffins have improved 17% and 72%, respectively. The conversion of the nitrobenzene is acceptable and the effect of the number of the tubes also has been taken into account. However, the performance of the new configuration needs to be tested experimentally over a range of parameters under practical operating conditions.     

Differentiation of post harvest date fruit varieties non‐destructively using FT‐NIR spectroscopy

The world production of dates has more than doubled over the last two decades. Presently, the industrial sorting of dates is a difficult operation, affected by a high level of losses. As a consequence, the objective of this article is to study the variety discrimination capabilities of Fourier Transform‐Near Infrared (FT‐NIR) reflectance spectroscopy for post‐harvest sorting purposes. The same methodology was tested on six commercial date varieties named Estamaran, Kabkab, Mazafati, Piarom, Deglet nour and Zahedi. For each cultivar, 100 fruits were analysed using the FT‐NIR spectrometer, subsequently characterised by destructive measurements. A multivariate analysis of the FT‐NIR spectra appears a feasible tool for cultivar discrimination and even to estimate the soluble solid content (SSC) and dry matter (DM) of dates at their optimal harvesting conditions. FT‐NIR, as a non‐destructive techniques, could be a suitable way for on‐line screening of different dates varieties.     

Constructing a block layout by face area

Solving the facility layout problems by graph theory consists of two stages. In the first stage, a planar graph that specifies desired adjacencies is obtained and in the second stage, a block layout is achieved from the planar graph. In this paper, we introduce face area as a new concept for constructing a block layout. Based on this idea, we present a new algorithm for constructing block layout from a maximal planar graph (MPG). This MPG must be generated from deltahedron heuristic. Constructed block layout by this algorithm satisfies all of adjacency and area requirements.     

An improved time-adaptive self-organizing map for high-speed shape modeling

In this paper, an improved active contour model based on the time-adaptive self-organizing map with a high convergence speed and low computational complexity is proposed. For this purpose, the active contour model based on the original time-adaptive self-organizing map is modified in two ways: adaptation of the speed parameter and reduction of the number of neurons. By adapting the speed parameter, the neuron motion speed is determined based on the distance of each neuron from the shape boundary which results in an increase in the speed of convergence of the contour. Using a smaller number of neurons, the computational complexity is reduced. To achieve this, the number of neurons used in the contour is determined based on the boundary curvature. The proposed model is studied and compared with the original time-adaptive self-organizing map. Both models are used in several experiments including a tracking application. Results reveal the higher speed and very good performance of the proposed model for real-time applications.