Swing angle estimation for anti-sway overhead crane control using load cell

Overhead crane movement results in suspended load sway, which may cause dangers and damages. Common anti-sway methods are based on swing angle information. This paper presents a novel method that uses load cell sensors for swing angle estimation. According to our proposed method, a damping signal is generated and added to the speed reference in order to suppress the suspended load sway. Conventional methods of swing angle estimation are based on measurement by camera vision, acceleration, or some other type of sensor. Compared to conventional methods, the proposed method based on load cell is simpler to build and less sensitive to ambient conditions. The effectiveness of the method is verified by computer simulation.     

Integrating analytical network process and fuzzy logic to prioritize the strategies - A case study for tile manufacturing firm

SWOT analysis is the most important tool for decision makers in strategic management process, because it enables the managers to discover and collect the facts that resulted from internal and external analysis. This analysis can be a good base for strategy formulation, but it is not non-defect. It includes no means of analytically determining the importance of factors or assessing the fit between SWOTS factors and decision alternatives and is mainly based on the qualitative analysis. Many researchers develop different techniques to quantify the SWOT analysis, but these methods are not comprehensive. In this study, we develop a fuzzy method model for quantitative weighing of SWOT strategies. The decision maker’s imprecise information is regarded by fuzzy numbers in this model. To consider dependency among factors and sub-factors, we use ANP technique in our research. We demonstrate our model with a case study example and compare results of our research with prior research.     

Counterfeit Integrated Circuits: Detection,Avoidance, and the Challenges Ahead

The counterfeiting of electronic components has become a major challenge in the 21st century. The electronic component supply chain has been greatly affected by widespread counterfeit incidents. A specialized service of testing, detection, and avoidance must be created to tackle the worldwide outbreak of counterfeit integrated circuits (ICs). So far, there are standards and programs in place for outlining the testing, documenting, and reporting procedures. However, there is not yet enough research addressing the detection and avoidance of such counterfeit parts. In this paper we will present, in detail, all types of counterfeits, the defects present in them, and their detection methods. We will then describe the challenges to implementing these test methods and to their effectiveness. We will present several anti-counterfeit measures to prevent this widespread counterfeiting, and we also consider the effectiveness and limitations of these anti-counterfeiting techniques.     

A probabilistic model for assessing the reliability of wind farms in a power system

Modeling the generation of a wind farm and its effect on power system reliability is a challenging task, largely due to the random behavior of the output power. In this paper, we propose a new probabilistic model for assessing the reliability of wind farms in a power system at hierarchical level II (HLII), using a Monte Carlo simulation. The proposed model shows the effect of correlation between wind and load on reliability calculation. It can also be used for identifying the priority of various points of the network for installing new wind farms, to promote the reliability of the whole system. A simple grid at hierarchical level I (HLI) and a network in the north-eastern region of Iran are studied. Simulation results showed that the correlation between wind and load significantly affects the reliability.     

Dendrigraft with citric acid on acrylonitrile/acrylic acid copolymer electrospun fibres

Acrylonitrile/acrylic acid copolymers were synthesized with different mole fractions (1, 2, 5 and 10 mol%) of acrylic acid (AA) in the feed by aqueous suspension polymerization, and bead‐free fibres (295–375 nm in diameter) were made from the copolymers in dimethylformamide solutions by electrospinning. In a heterogeneous system containing electrospun fibre mats, dendritic molecules were grown by reaction between carboxylic acid of AA and –OH groups of citric acid activated by dicyclohexylcarbodiimide. The products were analysed using ¹H NMR, ¹³C NMR and Fourier transform infrared spectroscopies, density determination, scanning electron microscopy, optical microscopy, differential scanning calorimetry and pH response properties. With decreasing AA content, the isotacticity of the copolymers decreases with a more random distribution of the co‐monomers which leads to higher percentage conversions of dendrigraft due to reduced steric hindrance. On the formation of dendrigraft, the percentage conversion of the reactions decreases with an increase of generation number and AA content. A reduction of density for the first generation and then an increase with increasing generation are observed. During oxidation stabilization of fibres with a decrease of AA content and an increase in generation number, the amount of liberated heat increases. Fibres containing more carboxylic groups show significantly greater amounts of swelling/de‐swelling in basic and acidic media, respectively. To be used as nanocarbon fibre precursors, or as active particles for loading with guest molecules, or as pH actuators, the first generation of dendrigrafted fibres are expected to have the greatest potential among the various samples examined. © 2013 Society of Chemical Industry     

Delay causes in Iran gas pipeline projects

On the basis of Iran's strategic development plan, natural gas industry must develop the capacity of gas transmission up to 1300 million m³ per day until 2025. For this purpose, gas pipeline length should be doubled during the next 15 years; however, experience shows a remarkable delay in nearly all gas pipeline projects. The main goal of this paper is to identify and rank the causes of delay in these kinds of projects in Iran. In this regard, 24 executed gas pipeline projects were studied and then extracted delay factors were conferred with 10 experts from several disciplines. The result was a 43-item list of factors which then was ranked by means of a questionnaire survey. The result reveals that the 10 major delay factors are: “imported materials, unrealistic project duration, client-related materials, land expropriation, change orders, contractor selection methods, payment to contractor, obtaining permits, suppliers, and contractor's cash flow”.     

Dynamic modeling of gas phase propylene homopolymerization in fluidized bed reactors

A new model with comprehensive kinetics for propylene homopolymerization in fluidized bed reactors was developed to investigate the effect of mixing, operating conditions, kinetic and hydrodynamic parameters on the reactor performance as well as polymer properties. Presence of the particles in the bubbles and the excess gas in the emulsion phase was considered to improve the two-phase model, thus, considering the polymerization reaction to take place in both the bubble and emulsion phases. It was shown that in the practical range of superficial gas velocity and catalyst feed rate, the ratio of produced polymer in the bubble phase to the total production rate is roughly between 10% and 13%, which is a substantial amount and cannot be ignored. Simulation studies were carried out to compare the results of the improved two-phase, conventional well-mixed and constant bubble size models. The improved two-phase and well mixed models predicted a narrower and safer window at the same running conditions compared with the constant bubble size model. The improved two-phase model showed close dynamic behavior to the conventional models at the beginning of polymerization, but starts to diverge with the evolution of time.     

Theoretical and practical investigations of copper ion selective electrode with polymeric membrane based on N,N′-(2,2-dimethylpropane-1,3-diyl)-bis(dihydroxyacetophenone)

A novel ion-selective poly(vinyl chloride) (PVC) membrane sensor for Cu²⁺ ions based on N,N′-(2,2-dimethylpropane-1,3-diyl)-bis(dihydroxyacetophenone) (NDHA) as a new ionophore was prepared and studied. The best performance was observed for the membrane composition, including 30:65:1:4 (wt%) = PVC:DBP:KTpClPB:NDHA. The electrode showed a good Nernstian slope of 30.0 ± 0.5 mV/decade in a wide linear range activity of 3.0 × 10⁻⁷ to 1.0 × 10⁻² mol dm⁻³ Cu(NO₃)₂ with limit of detection 2.5 × 10⁻⁷. Sensor exhibited a fast response time (t_95% < 10 s) and could be used for about 4 months in the pH range of 3.0–7.4. The proposed potentiometric sensor was found to work satisfactorily in partially non-aqueous media up to 30 (vol%) content of methanol, ethanol and acetone. Applications of this electrode for the determination of copper in real samples, and as an indicator electrode for potentiometric titration of Cu²⁺ ion using EDTA, were reported. In order to predict the extraction ability of NDHA for different metallic ions, the complexes [M(NDHA)] and [M(H₂O)₆] (where M = Cu²⁺, Co²⁺, Hg²⁺, Pb²⁺, Ag⁺, Mg²⁺, Ca²⁺, Mn²⁺, Zn²⁺, Cd²⁺, K⁺ and Al³⁺) were investigated using ab initio theoretical calculations. The metal binding capability was evaluated using the binding energy. Results of our study could be useful for prediction of the extraction power of this Schiff base and could play a guiding role in planning experiments.     

Binding of externally supplied chlorides in micro silica concrete under field exposure conditions

Chloride binding has remarkable influence on the chloride penetration and hence, on the time to corrosion initiation in reinforced concrete structures. Previous studies have mainly looked at the chloride binding from internal sources in laboratory, which is not representative of practical situations. The current work focuses on the chloride binding characteristics of concrete samples exposed to an external source of chlorides from the sea water at Persian Gulf region. Some of the important parameters including w/c ratio, silica fume replacement and effect of chloride concentration on chloride binding were investigated in order to provide insight into the distribution of free and bound chloride ions after a long-term exposure.The results of the current study suggest that the chloride binding capacity increases with increasing the w/c ratio and chloride concentration but decreases by using silica fume. A general equation was also developed correlating the total and bound chloride in order to obtain more accurate service life prediction.