Background: The aim of this study was to evaluate the effect of three types of light curing devices QTH, LED and Flashmax on the surface microhardness of three types of bulkfill composite resins; Filtek Bulkfill posterior composite ( 3M), Tetric Evo Ceram ( Ivoclar Vivadent) and Sonicfill composite ( Kerr) Materials and methods: Total number of 90 samples was prepared, 30 samples for each type of bulkfill composite, were divided into three main groups, group A: Filtek posterior bulkfil (3M), group B: Tetric Evo Ceram (Ivoclar Vivadent) and group C: contain Sonicfill composite (kerr). Which then divided into three subgroups (n= 10) (1) Samples cured by QTH system (2) Samples cured by LED system and (3) samples cured by Flashmax system then all samples were subjected for microhardness test (by Vickers hardness tester). The data were recorded and statistically analyzed, by the ANOVA and the Tukey test. Results: the data was subjected to statistical analysis using one way ANOVA and Tukey test, the result revealed that there was a high significant difference among the tested units with LED had high VHN values followed by QTH while Flashmax had lowest VHN values, also there was high significant difference among the tested materials in which Sonicfill composite had higher VHN value followed by Tetric EvoCeram while Filtek bulkfill posterior composite had the lowest VHN. Conclusions: microhardness of the composite resin materials depend upon energy of the curing device, time of exposure, composition of the composite material.
In this research a new system identification algorithm is presented for obtaining an optimal set of mathematical models for system with perturbed coefficients, then this algorithm is applied practically by an “On Line System Identification Circuit”, based on real time speed response data of a permanent magnet DC motor. Such set of mathematical models represents the physical plant against all variation which may exist in its parameters, and forms a strong mathematical foundation for stability and performance analysis in control theory problems.
The research deals with analyzing the influencing role of trade policies in the growth and development of productive economic sectors and their contribution to GDP and its reflection on workforce employment. Studies have proven the success of the Malaysian experience in stimulating the productive economic sectors to grow and their contribution to the gross domestic product with an increase in the growth of local markets and access to international markets for national products. The research also deals with the ineffectiveness of Iraqi trade policies after 2003 in stimulating the productive economic sectors (agricultural and industrial) on economic growth, as most of the increase in Iraqi GDP growth throughout the study period was
... Show MoreCurrent research targeted: Recognizing the impact of the differentiated education strategy on the achievement of the students of the Institute of Fine Arts / Diyala, for the academic year (2018-2019).
The researcher used the experimental approach designed by two groups (control - experimental) and with a post-test to achieve the goal of the research, and the research sample was chosen from students of the fourth stage for the academic year (2018-2019).
The sample was distributed randomly into two groups, the first experimental consisting of (30) students who studied using the differentiated education strategy, and the second control group consisting of (30) students who studied using the traditional method.
The researcher pre
Women's rights in social studies and national textbooks in the secondary stage in the light of the international charters of women's rights and the cultural specificity of the Saudi society Abstract The current study focuses on exploring women rights that required to be involved in social studies and national textbooks in the secondary stage in the light of international conventions on women's rights and cultural specificity of the Saudi society, as well as to reveal the teachers and educational supervisors' estimation about the degree of importance of those components included in the books, and then build a matrix of the range and sequence of women's rights in the books of social studies and national in the secondary stage. The study us
... Show MoreA particulate polymer composite material was prepared by reinforcing with the Aluminum Oxide (Al2O3) or Aluminum (Al) metallic particles with a particle size of (30) µm to an unsaturated Polyester Resin with a weight fraction of (5%, 10%, 15%, 20%).
Tensile test results showed the maximum value of elastic modulus reached (2400MPa.) in the case of reinforcing with (Al) particles with weight fraction (20%) and (1500 MPa.) in the case of reinforcing with (Al2O3) particles of the same weight fraction.
When the impact and the flexural strength tests were done, the results showed that flexural strength (F.S), maximum shear stress (τmax), impact strength
... Show MoreIn this current work, Purpose; to clearly the fundamental idea for constructing a design and
investigation of spur gear made of composite material its comes from the combination of (high
speeds, low noise, oil-les running, light weight, high strength, and more load capability)
encountered in modern engineering applications of the gear drives, when the usual metallic gear
cannot too overwhelming these combinations.
An analyzing of stresses and deformation under static and dynamic loading for spur gear tooth
by finite element method with isoparametric eight-nodded in total of 200 brick element with 340
nods in three degree of freedom per node was selected for this analysis. This is responsible for the
catastropic fa
Green areas are an essential component of city planning, as they serve as an outlet for them to spend their free time, in addition to the environmental role that these green areas play in improving the city’s climate by purifying the air and beautifying the city. The study’s problem is summarized in identifying the appropriateness of the current spatial distribution of green areas in the city of Najaf with the current population densities and the pattern in which green areas are distributed using GIS and knowing the per capita share of those green areas in the city, the research assumes that the inconsistency of spaces between regions Green and residential neighbourhoods need to c