Double-layer micro-perforated panels (MPPs) have been studied extensively as sound absorption systems to increase the absorption performance of single-layer MPPs. However, existing proposed models indicate that there is still room for improvement regarding the frequency bands of absorption for the double-layer MPP. This study presents a double-layer MPP formed with two single MPPs with inhomogeneous perforation backed by multiple cavities of varying depths. The theoretical formulation is developed using the electrical equivalent circuit method to calculate the absorption coefficient under a normal incident sound. The simulation results show that the proposed model can produce absorption coefficient with wider absorption bandwidth compared with the conventional double- and even triple-layer MPPs. The bandwidth can be increased to higher frequency by decreasing the cavity depth behind a sub-MPP with small hole diameter and a high perforation ratio, and to lower frequency by increasing the cavity depth behind a sub-MPP with large hole diameter and a small perforation ratio. The experimental data, measured by impedance tube, are in good agreement with the predicted results.
In this paper, the error distribution function is estimated for the single index model by the empirical distribution function and the kernel distribution function. Refined minimum average variance estimation (RMAVE) method is used for estimating single index model. We use simulation experiments to compare the two estimation methods for error distribution function with different sample sizes, the results show that the kernel distribution function is better than the empirical distribution function.
The use of containers in transportation leads to the reduction in time and effort of the process of loading and unloading of goods as well as protecting the goods from damage and breakage and to reduce the financial costs.
. This development has led also to make changes in the sizes and capacity of ships, therefore changes in the ports must be taken place where they must be provided with an appropriate depth for such vessels, that means the increase in the depth of ports and the establishment of wide storage yards and to provide appropriate mechanisms for handling process.
In this study, the researcher has dealt with this type of transport business in Iraqi ports, namely:
1- Khur Al-Zubair port.
2- Um Qaser port.
In order
A frequently used approach for denoising is the shrinkage of coefficients of the noisy signal representation in a transform domain. This paper proposes an algorithm based on hybrid transform (stationary wavelet transform proceeding by slantlet transform); The slantlet transform is applied to the approximation subband of the stationary wavelet transform. BlockShrink thresholding technique is applied to the hybrid transform coefficients. This technique can decide the optimal block size and thresholding for every wavelet subband by risk estimate (SURE). The proposed algorithm was executed by using MATLAB R2010aminimizing Stein’s unbiased with natural images contaminated by white Gaussian noise. Numerical results show that our algorithm co
... Show MoreTuberculosis is caused by Mycobacterium tuberculosis; it is considered as one of the most common, infectious diseases and major causes of morbidity and mortality worldwide. A prospective study was conducted to obtain more clarification about the impact of causative agent and its treatment to enhance autoantibodies production such as ANCA and BPI which used as diagnostic markers for several diseases, and to provide further insight into the classical risk factors (age and sex).Seventy patients with tuberculosis involved in this study, 35 of them were untreated and 35 with treatment administration these patients were attending to directorate of general health national reference laboratory in Baghdad during the period between November/ 2012
... Show MoreOur goal in this work is to describe the structure of a class of bimodal self maps on the compact real interval I with zero topological entropy and transitive.
Recent accumulated evidences suggest that prolactin is an important immunomodulator and may have a role in the pathogenesis of systemic lupus erythematosus (SLE). The aim of this study was to assess the frequency of hyperprolactinemia in women with SLE and to evaluate its correlation with disease flares. Serum prolactin levels were measured in 62 women with SLE and 50 age- and sex-matched healthy controls. In patients and control groups prolactin levels were determined by immunoradiometric assay (IRMA). The prolactin level was found to be higher than normal rang in (40.3%) of SLE patients in active stage versus only (8.06%) of the same SLE patients but in the inactive stage and in (4%) of control group, the elevation was ranging between mi
... Show MoreSupport Vector Machine (SVM) is supervised machine learning technique which has become a popular technique for e-mail classifiers because its performance improves the accuracy of classification. The proposed method combines gain ratio (GR) which is feature selection method with one-class training SVM to increase the efficiency of the detection process and decrease the cost. The results show high accuracy up to 100% and less error rate with less number of feature to 5 features.
In this paper, a hybrid image compression technique is introduced that integrates discrete wavelet transform (DWT) and linear polynomial coding. In addition, the proposed technique improved the midtread quantizer scheme once by utilizing the block based and the selected factor value. The compression system performance showed the superiority in quality and compression ratio compared to traditional polynomial coding techniques.
We define a new concept, called " generalized right -derivation", in near-ring and obtain new essential results in this field. Moreover we improve this paper with examples that show that the assumptions used are necessary.