Articles in This Issue
Abstract
In this research a simply supported beam is used as a master structure with unknown number of attachments (fuzzy substructure) which is modeled as a system of 1-DOF attachments. Two types of attachments models were studied, namely 1-DOF mass attachment model and 1-DOF mass-spring attachment model. It is shown that the effect of attachments on the master structure natural frequencies when modeled as (mass-spring substructure) is larger than that when modeled as (mass substructure) for the same attachment mass. Engineering Statistics and normal distribution were used to find the values of the attachments to be added to the simply supported beam to improve the dynamical properties of the master structure and to find the best distribution of the attachment. The results also show that the distribution of the additional substructure can produce a great change in the natural frequencies so that the proposed statistical approach can be used to find the best distribution of attachments and number, value and location of the additional substructure .
Abstract
This paper specifies a proposed improvement model of Data Encryption Standard (DES) which may be used to protect sensitive data. Protection of data during transmission may be necessary to maintain the confidentiality and integrity of the transformation represented by data. Instead of expansion step in each round which made by copying 16 bit from 32 bits data in each right side of the standard algorithm, the unused 8-bits as a key (sometimes it is used for error detection and correction purposes, or it is possible to generate an additional 8-bits with the 56-bits standard key) in the first starting round with the other 8-neglected bits from each of 16 round in the key algorithm will be used, and take the same locations of the expanded data. As a result, the complexity to cryptanalysis of the secured data has been increased. The proposed method was more active and reliable than standard conventional DES, where it can be switched to the system at any round for working with original DES algorithm, which means that an additional security has been added
Abstract
The feasibility of using an Artificial Neural Network (ANN) for controlling time- varying dynamical system is presented. The direct adjusting of neural controller by direct adaptive control (DAC) is available, by using the error between output of plant and desired input. The finite recurrent back propagation (FRBP) is used in the learning process, because the ability of this method to capture the nonlinearly and overcome the problem of time varying system. Hybrid controller structure used in this paper, where the parameters of classical controller are adjusted with time at specified freezing points for time varying dynamical system, and summed the outputs of two controllers and enter to the plant, identify of system by ANN to get the optimal initial condition for neuro controller. A single channel for Spacecraft model is used as an example in this paper, satisfactory results are obtained, which explain the ability of recurrent neural network (RNN) to identify time varying dynamical system and overcome for all its problem and explain the ability of this structure of hybrid neuro controller to use with time varying dynamical system.
Abstract
Minor component analysis (MCA) of lower dimensional data is related to many signal processing applications. MCA strives to extract the "minor" direction in the data space where the variance of the data is minimal, identify the way for dimension reduction and data compression. In this paper neural networks are used to estimate the minor component of signal. This component is used to determine the Direction of Arrival Estimation (DOA) of incident signals. These signals are considered to be emitted from their emission sources .The neural networks knowing “Hebbian-networks” are used to estimate the minor component directions from signal subspace. Narrow band signals are considered here and strike an array composed of M sensors. Simulation results are introduced to shown the performance of the adaptive neural networks to estimate signal components, a comparison of the results obtained from classical method and MCA method, is presented which shows the performance of MCA over classical methods, to estimate exact signal direction from noise subspace.
Abstract
Determinations of unsaturated soil parameters using experimental procedures are time consuming and difficult. In recent years, the soil–water characteristic curve (SWCC) has become an important tool in the interpretation of the engineering behavior of unsaturated soils. Difficulties associated with determining such parameters have justified the use of indirect determination. This paper presents the general nature of the SWCC for soils with different plasticity limits, index and gradation, in terms of gravimetric water content and degree of saturation versus soil matric suction from Anbar governorate. In order to investigate possible relationships between the plasticity limits, index, percent passing no.200 and SWCC, 7 type of soils were tested to find its SWCC experimentally and compared the result with the curves obtained from different model presented in the literature. The objectives of the paper were to check the validity of these models with the experimental results. The results shows a good agreement and to present a simple method for inferring the SWCC for soils, taking into account the liquid limit, plastic limit, plasticity index and percent of fines passing sieve no.200.
Abstract
Using statistical tools of quality help in identifying the daily production problems.Collecting data will enable the management to diagnose problems affecting the work and correcting the defects in the products and reduce its percentage; such defects cost the organization too much and influence its profits. Histograms were used in presenting the collected data from Amanat Baghdad. The data related to asphaltic concrete produced by its plants . Control charts were used to evaluate these tests. The research indicates differences in the results of mechanical analysis tests also in the asphalt percentage in the asphaltic concrete samples and air voids ratio as in Marshall samples. The results indicated that management of plants has no benefits gained from results tests carried out by the quality control department which indicate and diagnose the variances of the product and recommend the required corrections.
Abstract
In this research, the effect of adding fillings of steel resulting from factory of smithery was studied. The fiber was added with two different percentages to the ordinary and polymer concrete to study their effects on some of the properties of both type of concrete like compressive strength, flexural strength and density. Two different percentages of fiber by volume of concrete (0.5%, 1.0%) were added to concrete mixes. A reference mix was also made. The results showed that adding of fillings of steel with these percentages lead to improvements in both compressive strength and flexural strength of polymer concrete with the increase of its percentage while it's less effect on these properties of ordinary concrete. An improvement in flexural strength appeared more clearly in both type of concrete. Significant increase in density was noted in both types of concrete.