A Simplified Formula for Calculating the Critical Load of the Needles Used in the Needle-punching Machine

The needle-punching machine is used for producing nonwoven fabrics. The needle is considered to be a very important member in the machine. The failure of the needle (simple or compound) during punching under the effect of the compressive force causes fabric defects and delays in production.

In this paper, a theoretical approach is applied to calculating the load above which the needle loses its elastic stable equilibrium. It is shown that the coefficient of the elastic stable equilibrium, n is 1.4706 for the compound needle and 1.1116 for the simple needle. The calculations were made by the use of an mz 80K personal computer.     

Multi-objective Optimization Approach for Optimal Distributed Generation Sizing and Placement

Abstract—This article describes a multi-objective optimization method to solve the optimal distributed generation sizing and placement. The optimization problem considers two objectives: minimizing the total real power losses of the network and minimizing the overall distributed generation installation cost. The objectives are combined into a scalar objective optimization problem by using weighted sum method. Both objective functions and equality and inequality constraints are formulated as a non-linear program and solved by a sequential quadratic programming deterministic technique. The multi-objective optimization method gives several answers instead of a single (unique) one. These answers are optimal, and the designer (decision maker) can select the proper solution according to subjective preferences. These optimum results are known as the Pareto front. A fuzzy decision-making procedure for order preference is used for finding the best compromise solution from the set of Pareto solutions. The proposed method is tested using a 15-bus radial distribution system to show its applicability. A comparative study is performed to evaluate two cases—a single distributed generation unit installation and a multiple distributed generation installation—ending by a comparative study of the two cases.     

Optimal Parameter Estimation for Hydro-Plant Performance Models in Economic Operation Studies

Optimal Economic Operational schedules in hydro-thermal electric power systems are obtained on the basis of models of the various subsystems involved. In this paper we are concerned with models of hydro-plant performance characteristics. Due to the diversity of plant types and installations, a number of models have been proposed in developing optimal operational strategies over the years. Here we choose four commonly used models. The problem of finding optimal estimates of model parameters is investigated for the Glimn-Kirchmayer model, the Hildebrand model, the Hamilton-Lamont model and the Arvanitidis-Rosing model. We develop the optimal estimator equations for each model using the weighted-least-squares approach. The result for three of the models is a set of nonlinear equations in the unknown parameters. We adopt Newton's method for actually implementing the optimal estimators. Due to the sensitivity of the algorithm's convergence characteristics to the initial guess of the unknowns, we explore and present procedures for generating initial guess values to improve the procedure's performance. Computational experience with the techniques is given in the paper to confirm its feasibility using test data from existing hydro-plants. The paper proposes and examines some extensions to the classical models to improve the accuracy of the modeling process.     

Copolymerization of vinyl acetate with methyl N-(1-cyanopropene-2-yl)itaconamate

Summary Vinyl acetate copolymerized with methyl N-(1-cyanopropene-2-yl)itaconamate(I) forming low molecular weight copolymer containing about 8% of I. I was prepared by methylating potassium N-(1-cyanopropene-2-yl)itaconamate. The amic acid of the last salt as well as N-(1-cyanopropene-2-yl)maleamic and N-(10cyanopropene-2-yl)citraconamic acids could not be dehydrated to the corresponding imides using acetic anhydride-sodium acetate mixture. High melting, water-soluble polymeric products that could not be crystallized were always the products. These results confirm earlier related studies. Therefore, vinyl containing amic acids having allylic substituents on their nitrogen atoms may not be dehydrated to the corresponding imides by acetic anhydride-sodium acetate mixtures.     

Effect of Weather Conditions on Harmonic Performance of PV Inverters

Abstract

The effect of weather conditions on the generation of harmonics in PV systems is investigated. A PV model, including the inverting stage, is considered. The output of the equivalent PV model is fed to the load via an inverter and transformer. The analysis is conducted by using a dataset of weather conditions in a North American city. Two converter techniques, which form the basis for the majority of converters, are used to validate the proposed approach: a square-wave inverter with 60?Hz switching, and pulse width modulation (PWM). Probability density functions and probability distribution models with best fit are determined as aids for improving the quality of the power generated for different range of converter values and the best is selected in this article. The long-term effects of weather conditions on harmonics produced by PV inverters are considered. The results show the variability in amplitude of each harmonic component, the boundaries of each harmonic component, and which harmonic magnitudes occur more frequently. The classic PV DC-AC conversion system has been modeled using MATLAB. The work is validated by using different ranges of dataset for two different converters and the results improved the importance of the proposed work. Also, the results agree with previous studies that have been carried with a different method which could be considered as another way of validation for the proposed work. Based on the generated harmonic variation cases, the appropriate parameter values for dynamic adaptive circuit switching of the filtering system and determining the capacity of the storage system could be determined.     

Magnetic Susceptibility Study of Sub‐Pico‐emu Sample Using a Micromagnetometer: An Investigation through Bistable Spin‐Crossover Materials

A promising and original method to study the spin‐transition in bistable spin‐crossover (SCO) materials using a magnetoresistive multiring sensor and its self‐generated magnetic field is reported. Qualitative and quantitative studies are carried out combining theoretical and experimental approaches. The results show that only a small part of matter dropped on the sensor surface is probed by the device. At a low bias‐current range, the number of detected nanoparticles depends on the amplitude of the current. However, in agreement with the theoretical model, the stray voltage from the particles is proportional to the current squared. By changing both the bias current and the concentration of particle droplet, the thermal hysteresis of an ultrasmall volume, 1 × 10^?4 mm³, of SCO particles is measured. The local probe of the experimental setup allows a highest resolution of 4 × 10^?14 emu to be reached, which is never achieved by experimental methods at room temperature.     

Performance evaluation of modified fabricated cotton membrane for oil/water separation and heavy metal ions removal

Preparation of effective membrane with special surface treatment for oil/water separation having promising future and low manufacturing cost. The suggested membrane was fabricated by a simple treatment via increasing the hydrophilicity of the cotton fabric surface. The cotton fabric was impregnated in poly(acrylic acid-co-N-methylol acrylamide), poly(AA-co-NMA), where NMA acts as bonding agent. Sodium hypophosphite (SHP) was added to the modification solution to enhance the bonding between the cotton fabric and the PAA. The modified fabric was thermally dried and cured at different temperatures. It was found that, the presence of 3.5% NMA and addition of 5% SHP to the modification solution then curing at 190°C gave the highest amount of bonded PAA to the cotton fabric. The success of the modification process was confirmed by scanning electron microscope, Fourier transformer infrared and the increase in the contact angle of the cotton fabric after modification. Furthermore, the prepared membrane was evaluated for oil (n-hexane, toluene, and petroleum ether)/water separation and also for heavy metal ions removal (Cd²⁺ and Co²⁺). Neutralization of the produced membrane with ammonium hydroxide resulting in a higher contact angle and consequently higher separation efficiency for oil/water mixtures and higher performance for heavy metal ions removal compared to the unneutralized one.     

Fractional Laguerre spectral methods and their applications to fractional differential equations on unbounded domain

In this article, we first introduce a singular fractional Sturm–Liouville problem (SFSLP) on unbounded domain. The associated fractional differential operator is both Weyl and Caputo type. The properties of spectral data for fractional operator on unbounded domain have been investigated. Moreover, it has been shown that the eigenvalues of the singular problem are real-valued and the corresponding eigenfunctions are orthogonal. The analytical eigensolutions of SFSLP are obtained and defined as generalized Laguerre fractional-polynomials. The optimal approximation of such generalized Laguerre fractional-polynomials in suitably weighted Sobolev spaces involving fractional derivatives has been derived. We construct an efficient generalized Laguerre fractional-polynomials-Petrov–Galerkin methods for a class of fractional initial value problems and fractional boundary value problems. As a numerical example, we examine space fractional advection–diffusion equation. Our theoretical results are confirmed by associated numerical results.