Ceramic to metal joining technique, which was used in this investigation includes the use of active filler alloy as a sandwich between the alumina and kovar alloy for brazing. High purity powdered metals of silver, copper, and additives of titanium were used to prepare the active filler alloy, through compacting the mixed powders and alloying in a furnace with argon atmosphere at the temperature of 800oC for 10 minutes. To use it as an active filler metal, it has been modified to a proper thickness. Two groups of alumina were prepared with different sintering temperatures (1450oC and 1650oC) and each group was tested under atmospheric pressure, vacuum furnace pressure of 2*10-4 torr and vacuum furnace pressure of 2*10-6 torr. All the process was at a same brazing temperature of 850C for 20 minutes. A reliable joint between the different types of alumina and kovar alloy was achieved by using vacuum furnace. On the other hand, weak bond was obtained by using atmospheric furnace. A maximum value of joint strength between alumina and kovar was obtained (130 MPa) under condition of 2*10-6 torr of vacuum furnace
The aim of this study is to compare the effects of three methods: problem-based learning (PBL), PBL with lecture method, and conventional teaching on self-directed learning skills among physics undergraduates. The actual sample size comprises of 122 students, who were selected randomly from the Physics Department, College of Education in Iraq. In this study, the pre- and post-test were done and the instruments were administered to the students for data collection. The data was analyzed and statistical results rejected null hypothesis of this study. This study revealed that there are no signifigant differences between PBL and PBL with lecture method, thus the PBL without or with lecture method enhances the self-directed learning skills bette
... Show MoreWe conducted an experiment in a greenhouse at the research station belonging to the Department of Plant Protection / Ministry of Agriculture, in Abu Ghraib area during the spring and autumn season 2022-2023, to study the population density of the whitefly on two varieties of sweet pepper plant (Charisma and Sierra Nevada). The experiment was laid out in a randomized complete block design “RCBD” with three replicates for each variety. The results showed that in spring season the population density of
The tunnel’s stability during construction is a very important matter. Some methods have been proposed for stability evaluation, but the hazard warning levels (HWLs) are more applicable among these methods. Despite monitoring and applying HWLs, several collapses in Shibli twin tunnels in Iran have cast doubts on the accuracy of this criterion in the presence of water. In this study, the critical strains under different water contents were measured through uniaxial compressive strength tests on 11 different shale and marl samples. A comparison of laboratory tests and numerical results shows that the influence of the moisture content on the critical strain is negligible. In addition, the results show that there is no dir
... Show MoreBackground: Breast cancer is the most common cancer in Iraq and the United Kingdom. While the disease is frequently diagnosed among middleaged Iraqi women at advanced stages accounting for the second cause of cancer-related deaths, breast cancer often affects elderly British women yielding the highest survival of all registered malignancies in the UK. Objective: To compare the clinical and pathological profiles of breast cancer among Iraqi and British women; correlating age at diagnosis with the tumor characteristics, receptor-defined biomarkers and phenotype patterns. Methods: This comparative retrospective study included the clinical and pathological characteristics of (1,940) consecutive female patients who were diagnosed with invasive b
... Show MoreDue to the great losses caused by weeds to the crop, it is necessary to continue testing new herbicides that may be more efficient than the herbicides used that can reduce competition between weeds and crops, Therefore, a field experiment was carried out in the experimental field of the Department of Field Crops, College of Agricultural Engineering Sciences, University of Baghdad (Al-Jadriya) during the winter season of 2021-22 in order to evaluate the efficiency of the herbicide H-199 and compare it with some herbicides used in controlling companion weed to three cultivars of wheat and its effect in the yield and its components. The experiment was applied according to the randomized complete block design with split-plot arrangement
... Show MoreThis paper proposes a new approach, of Clustering Ultrasound images using the Hybrid Filter (CUHF) to determine the gender of the fetus in the early stages. The possible advantage of CUHF, a better result can be achieved when fuzzy c-mean FCM returns incorrect clusters. The proposed approach is conducted in two steps. Firstly, a preprocessing step to decrease the noise presented in ultrasound images by applying the filters: Local Binary Pattern (LBP), median, median and discrete wavelet (DWT),(median, DWT & LBP) and (median & Laplacian) ML. Secondly, implementing Fuzzy C-Mean (FCM) for clustering the resulted images from the first step. Amongst those filters, Median & Laplace has recorded a better accuracy. Our experimental evaluation on re
... Show MoreSpent catalysts for sulfuric acid production have large amount of vanadium and due to environmental authority it is required to reduce the vanadium contain of the spent catalyst. Experimental investigation was conducted to study the vanadium recovery from spent catalyst via leaching process using sodium hydroxide to study the effect of process variables (temperatures, sodium hydroxide molarities, leaching time and particle size) on vanadium recovery. The effect of process variables (temperature, particle size,molarities of sodium hydroxide and leaching time) on the percentages of vanadium recovery were investigated and discussed .It was found that the percentage of vanadium recovery increased with increasing temperature up to 100 , incre
... Show MoreThat the structural changes in the environment, business and finance and the spread of business and the diversity of transactions between economic organizations and breadth of a commercial scale in the world have left their clear on the need to keep up with the accounting for these variables as one of the social sciences affect and are affected by the surrounding environment because of the various economic and social factors, technical, legal and others.
As a result of these variables emerged a new field of accounting called Forensic Accounting, which involves the use of expertise of multiple pour in the end to the accounting profession, where the Forensic Accounting cover a large area of disciplines including strengthening
... Show MoreBackground and Aim: due to the rapid growth of data communication and multimedia system applications, security becomes a critical issue in the communication and storage of images. This study aims to improve encryption and decryption for various types of images by decreasing time consumption and strengthening security. Methodology: An algorithm is proposed for encrypting images based on the Carlisle Adams and Stafford Tavares CAST block cipher algorithm with 3D and 2D logistic maps. A chaotic function that increases the randomness in the encrypted data and images, thereby breaking the relation sequence through the encryption procedure, is introduced. The time is decreased by using three secure and private S-Boxes rather than using si
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