Axial behavior of the steel reinforced lightweight aggregate concrete (SRLAC) short columns

Mostafa M. A. Mostafa,Tao Wu,Xi Liu,Bo Fu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.5

The composite steel reinforced concrete (SRC) columns have been widely used in Structural Engineering due to their good performances. Many studies have been done on the SRC columns' performances, but they focused on the ordinary types with conventional configurations and materials. In this study, nine new types of steel reinforced lightweight aggregate concrete (SRLAC) short columns with cross-shaped (+shaped and X-shaped) steel section were tested under monotonically axial compressive load; the studied parameters included steel section ratio, steel section configuration, ties spacing, lightweight aggregate concrete (LWAC) strength, and longitudinal bars ratio. From the results, it could be found that the specimens with larger ties ratio, concrete strength, longitudinal bars ratio, and steel section ratio achieved great strength and stiffness due to the excellent interaction between the concrete and steel. The well-confined concrete core could strengthen the steel section. The ductility and toughness of the specimens were influenced by the LWAC strength, steel section ratio, and longitudinal bars ratio; in addition, larger ties ratio with smaller LWAC strength led to better ductility and toughness. The load transfer between concrete and steel section largely depends on the LWAC strength, and the ultimate strength of the new types of SRLAC short columns could be approximately predicted, referring to the codes’ formulas of ordinary types of steel reinforced concrete (SRC) columns. Among the used codes, the BS-5400-05 led to the most conservative results.

Analysis and design of eccentrically loaded lightweight aggregate concrete-encased steel slender columns

Mostafa M.A. Mostafa 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.1

This paper presents a finite element (FE) simulation of eccentrically loaded lightweight aggregate concrete-encased steel (LACES) columns with H-shaped steel sections, analytical equations are also established to estimate the columns’ axial and bending moment interaction capacities. The validity of the proposed models is checked by comparing the results with experimental data. Good agreements between the test and proposed models’ results are found with acceptable agreements. Moreover, design parameters, including the lightweight aggregate concrete (LWAC) strength, eccentricity, column slenderness ratio, and confinement, are studied using the FE analysis, and their efficiency factors are discussed. The results show that the ultimate axial capacity of the LACES composite columns subjected to eccentric loading is negatively affected by the increase in the columns’ height, but it is positively affected by the increase of the confinement. Increasing the eccentricity and columns’ height reduced the columns’ stiffness. In addition, the ultimate capacity of the LACES column is significantly influenced by the LWAC strength and eccentricity, where the ultimate capacity of the LACES column is significantly increased by increasing LWAC strength, and it is remarkably decreased by increasing the eccentricity. When the eccentricity changed from zero to 70 mm, the ultimate axial capacity and stiffness decreased by 67.97% and 63.56%, respectively.

Rice Breeding in Iran, Current Status and Future Perspective

Mostafa Modarresi(Mostafa Modarresi ) 한국육종학회 2023 Plant Breeding and Biotechnology Vol.11 No.2

Rice is one of the most important sources of energy for Iranians. Currently, approximately four million tons of paddy are produced annually in 19 provinces of the country. More than 50 new rice cultivars have been introduced in Iran over the last 60 years. The average yield of rice in these years has increased from 2 t ha‒1 to nearly 5 t ha‒1 in farmers’ paddies, although some improved cultivars can produce up to 9 t ha‒1. The main strategy of rice breeding in Iran during the first 40 years was purifying local populations, introducing foreign lines, and producing high-yielding cultivars by cross-breeding and mutagenesis. Meanwhile, the production of high-quality cultivars from crosses between local varieties and high-yielding cultivars has been more emphasized recently. In this review, along with introducing improved varieties of Iranian rice and their characteristics, different improvement methods for creating these varieties are mentioned. Along with traditional breeding methods, it seems that Marker-assisted breeding and breeding by rational design can play important roles in the future of rice breeding in Iran.

Towards a new potential field theory of fractal objects

Mostafa E. Mostafa 한국지질과학협의회 2010 Geosciences Journal Vol.14 No.4

The Potential Field Anomaly (PFA) data of the self similar Fractal Objects (FOs) include gravity and magnetic fields and potentials along with the related derivatives. These elements are calculated on grids due to buried FOs at different fractal orders. The objects have variable physical property distributions; while in magnetic, the orientation and magnitude of polarization or earth magnetic field is arbitrary. Using the structural index as Universal Fractal Order Invariant Measure, one of the contributions of this work is expressing the elements of the PFA data at any measuring point on a grid as geometric sequences in terms of the fractal order. We found that the common ratio of the sequences is equal to the Fractal Mass Ratio (FMR), a physical quantity characterizing the object. Therefore, we can interpolate the PFA data backward or forward from one fractal order to the other. This in turn allows us to directly calculate PFA data of FOs from the zero order objects equivalent to the solid sources or initiators. We conclude that the patterns of PFA data due to a self similar FO are scale-invariant and reflect the nature of this object. We express the FMR of a FO in a new equation describing the difference between the topological and fractal dimensions in terms of a linear scale.

The Impact of Business Intelligence on the Relationship Between Big Data Analytics and Financial Performance: An Empirical Study in Egypt

Mostafa Zaki HUSSEIN(Mostafa Zaki HUSSEIN ),Samhi Abdelaty DIFALLA(Samhi Abdelaty DIFALLA ),Hussein Abdelaal SALEM(Hussein Abdelaal SALEM ) 한국유통과학회 2023 The Journal of Asian Finance, Economics and Busine Vol.10 No.2

The purpose of this research is to investigate the impact of Business Intelligence (BI) on the relation between Big Data Analytics (BDA) and Financial Performance (FP), at the beginning we reviewed the academic accounting and finance literature to develop the theoretical framework of business intelligence, big data and financial performance in terms of definition, motivations and theories, then we conduct an empirical analysis based on questionnaire-base survey data collected. The researchers identified the study population in the joint-stock companies listed on the Egyptian Stock Exchange and operating in the sectors and activities related to modern technologies in information systems, big data analytics, and business intelligence, in addition to the auditing offices that review the financial reports of these companies, and The sector closest to the research objective is the communications, media, and information technology sector, where the survey list was distributed among the sample companies with (15) lists for each company, and (15) lists for each audit office, so that the total sample becomes (120) individuals (with a response rate 83.3%), The results show, First, Big data analytics significantly affect organizations’ financial performance, second, Business intelligence mediates (partial) the relationship between big data analytics and financial performance.

Axial behavior of steel reinforced lightweight aggregate concrete columns: Analytical studies

Mostafa M. A. Mostafa,Tao Wu,Bo Fu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.2

This paper presents the analytical modeling and finite element (FE) analysis, using ABAQUS software, of the new types of steel reinforced lightweight aggregate concrete (SRLAC) columns with cross-shaped (+shaped and X-shaped) steel section, using proposed three analytical and two FE models in total. The stress-strain material models for different components in the columns, including the confined zones of the lightweight aggregate concrete (LWAC) using three and four concrete zones divisions approaches and with and without taking into account the stirrups reaction effect, are established first. The analytical models for determining the axial load-deformation behavior of the SRLAC columns are drawn based on the materials models. The analytical and FE models’ results are compared with previously reported test results of the axially loaded SRLAC columns. The proposed analytical and FE models accurately predict the axial behavior and capacities of the new types of SRLAC columns with acceptable agreements for the load-displacement curves. The LWAC strength, steel section ratio, and steel section configuration affect the contact stress between the concrete and steel sections. The average ratios of the ultimate test load to the three analytical models and FEA model loads, Put /Pa1, Put /Pa2, Put /Pa3, and Put /PFE1, for the tested specimens are 0.96, 1.004, 1.016, and 1.019, respectively. Finally, the analytical parametric studies are also studied, in terms of the effects of confinement, LWAC strength, steel section ratio, and the reinforcement ratio on the axial capacity of the SRLAC column. When concrete strength, confinements, area of steel sections, or reinforcement bars ratio increased, the axial capacities increased.

The Composite Steel Reinforced Concrete Column Under Axial and Seismic Loads: A Review

Mostafa M. A. Mostafa,Tao Wu,Xi Liu,Bo Fu 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.6

The composite steel reinforced concrete (SRC) columns with the form of partial or full encasement of the steel section in the reinforced concrete (RC) have attracted pervasive attention due to their advantages compared to the conventional RC columns. This paper aims to summarize the representative publications regarding the SRC columns. Firstly, the analytical studies of the SRC columns, including comparative studies between available codes to address the philosophy of design and the limits in the available codes of design, bond slip behavior, analytical confi nement material models, and fi nite element analysis, are addressed. In addition, the discussion and summary of the axial behavior of the SRC columns and the important parameters aff ecting the axial behavior of these types of columns were included. It also attempts to cover the parameters aff ecting the seismic behavior of the SRC columns. Important progress has been made by the previous studies in the SRC columns under the axial load and the combination of axial and seismic loads, but they fundamentally focused on the columns with the simple arrangement of steel section, and a few attention was paid to the new type of SRC columns with rotated cross-shaped steel section whose webs coincide with the diagonal lines of the columns’ section. Due to the lack of study and the brittle failure of the columns with lightweight and high strength concrete, more studies should still be made to know the behavior of the SRC columns. The paper concludes with suggestions for the future studies to enhance the eff ectiveness of the SRC columns.

Microbial colonization of sacral nerve stimulators pseudo-capsule: A single institution experience

Mostafa M. Mostafa,Mohamed Kamel,Ayman Mahdy 대한비뇨의학회 2023 Investigative and Clinical Urology Vol.64 No.5

Purpose: To evaluate the incidence and type of microbial colonization of the pseudo-capsule (PC) that forms around sacral nerve stimulators (SNS) and consequently the significance of surgical excision of this PC at time of SNS revision or removal. Materials and Methods: A cohort of 31 patients who underwent SNS revision or removal from January 2018 to June 2021 were retrospectively reviewed. The baseline demographics, rate and type of PC microbial colonization and development of SNS insertion site infection were reported. Results: A cohort of 31 patients who underwent “InterStim device (Medtronic)” revision or removal were included. The majority were females (93.5%). The most common indication for SNS insertion was refractory overactive bladder (67.7%). Nine patients (29.0%) underwent SNS revision due to malfunctional device, and 9 patients had SNS removal for the need of MRI procedures. Four patients (12.9%) had positive tissue culture growing Coryneform bacillus (50.0%), Cutibacterium acnes (25.0%) and Pseudomonas aeruginosa (25.0%). Conclusions: PC colonization was uncommon at the time of SNS explant. However, more research is needed to better understand the role of PC-positive culture in increasing the risk of SNS device infections if strict adherence to sterile techniques is adopted.

Numerical FE Modeling and Design Methods of CCES Columns with Normal-Weight Crushed Dolomite Coarse Aggregate Fully Embedded IPE Steel-Section

Mostafa M.A. Mostafa 한국콘크리트학회 2024 International Journal of Concrete Structures and M Vol.18 No.2

The composite concrete-encased steel (CCES) column member is made by the steel section embedded and covered in concrete from all sides. Due to the ability of the composite sections to bear heavy loads while using smaller sections, CCES columns have been widely used. Analytical studies on the CCES columns’ behavior using crushed dolomite coarse aggregate (CDCA) with different shear connectors (SCs) types/shapes and sizes under axial loads are described here. This study also aims to evaluate the current design methods to determine the ultimate capacity of the CCES with CDCA concrete columns using nine available codes. The results show that the finite element (FE) analysis could accurately predict the ultimate capacity of the CCES columns; the column’s capacity improved by about 41.75% as fcu increased by 60%. Increasing the IPE-shaped steel strength (fss) strategy is not very effective and gives brittle behavior even though enhancing the fss improves the capacity. The column's capacity increased as the tie stirrups and steel bars ratios increased. The column’s capacity increased by about 17.63%, as steel bars ratios increased by 155.49%. The efficiency factors increased slightly as tie stirrups were raised but slightly decreased as steel bar ratios increased. Using the SCs system increases the columns’ capacity by an average value of about 4.9% of the specimen without SCs. The computed capacities using the nine available codes are conservative and safe. The closest estimates made by the YB9082-06 code are 26% less on average than the test results; in contrast, the safest predictions made by the ECP-LRFD code are 68% less, on average, than test results.

Utilization Of Electrical Voltage For Improving Anaerobic Digestion Of Long Chain Fatty Acids: Will Connection Matter?!

Alsyed Mostafa(alsyed mostafa),Dong-Hoon Kim(김동훈),Seongwon Im(임성원),Young-Chae Song(송영채),Seoktae Kang(강석태) 대한환경공학회 2021 대한환경공학회 학술발표논문집 Vol.2021 No.11