A filter design approach to maximize ampacity of cables in nonsinusoidal power systems

This paper presents an optimal design of the C-type passive filters for the effective utilization of the power cables under nonsinusoidal conditions based on maximization of the harmonic derating factor (HDF) of a power cable, where maintaining the load true power factor at an acceptable range is desired. According to IEEE Standard 519, the total harmonic distortions of the voltage and current measured at the point of common coupling are taken into account as main constraints of the proposed approach. The presented numerical results show that the proposed approach provides higher current carrying capacity, or ampacity of the cables under nonsinusoidal conditions when compared to the traditional approaches based on minimization of the current total harmonic distortion and maximization of the true load power factor. A numerical case study is presented to demonstrate the proposed approach

Optimal multiple-steps single-tuned harmonic filters under time-varying conditions

Nowadays, considering the time-varying nature of harmonic sources is a significant trend in the power quality studies. In this research, the optimum sizing of multiple-steps passive LC compensator for maximum power factor and minimum transmission loss for non-linear loads under time varying conditions of background harmonic voltages, system impedance, and load impedance, is determined. The source harmonic voltages are varying in time independently of each other. The equivalent system impedance is given by varying the Thevenin impedance over a finite period. The functioning of the concerned LC filter is explained through a representative case study. Simulation results illustrate the viability of the suggested approach

Big data optimization in electric power systems: a review

There are different definitions of big data, and among them, the most common definition refers to three or five characteristics, called volume, velocity, variety, value, and veracity from (Laney (2001)). Volume could include Tera Byte, Peta Byte, Exa Byte, and Zetta Byte. Velocity describes how fast the data are retrieved and processed ‘‘Batch or streaming”. Variety describes structured, semi-structured, and unstructured data (Laney, 2001, Zikopoulos and Eaton, 2011). Veracity explains the integrity and disorderliness of data, while value refers to how good is the “value” we derive from analyzing data? (Zicari et al., 2016). Electrical power systems are networks of components arrayed to supply, transfer, and use electric power. In power system since models are used to predict and characterize operations. However, there is a necessity for powerful optimization algorithms for information processing to learn models as the size increase of data is becoming a global problem to solve large-scale optimization problems. Any optimization problem includes a real function to be maximized or minimized by systematically determination of input values from an allowed set of values. Richness and quantity of large data sets provide the potential to enhance statistical learning performance but require smart models that use the latent low-dimensional structure for effective 2 data separation. This chapter reviews the most recent scientific articles related to large and big data optimization in power systems. Optimization issues such as logistics in power systems and techniques including nonsmooth, nonconvex, and unconstrained large-scale optimization are presented. After a brief review of big data, scientometric analysis has been applied using keywords of “big data” and “power system.” Besides, keywords analysis, network visualization, journal map, and bibliographic coupling analysis have been done to draw a path on big data works in power system problems. Also, the most common useful techniques in large-scale optimization in power system have been reviewed. At the end of this chapter, metaheuristic techniques in big data optimization are reviewed to show that many efforts have been involved in big data optimization in power system and systematically highlight some perspectives on big data optimization

Clinical, anthropometric, radiological and molecular characteristics of Egyptian achondroplasia patients

Background: Achondroplasia is the most common form of non lethal skeletal dysplasia. It is a fully penetrant autosomal dominant disorder and the majority of cases are sporadic resulting from de novo mutations associated with advanced paternal age. The phenotype of achondroplasia is related to disturbance in endochondral bone formation due to mutations in the fi broblast growth factor receptor-3 (FGFR3) gene. Aim of the Work: Evaluation of the cardinal phenotypic features in achondroplasia, the body physique using anthropometric measurements, the characteristic radiological signs in the patients as a main tool for diagnosis and detection of the most common mutations in achondroplasia patients in the studied sample.Subjects and Methods: From 42 cases referred to us as achondroplasia, we selected 20 cases where clinical manifestations were consistent with achondroplasia. Cases were subjected to full clinical examination, detailed anthropometric measurements, whole body skeletal survey and molecular studies of the most common mutations of the FGFR3 gene using PCR amplifi cation technique. Results: Nineteen cases were sporadic (95%) and one case had an affected father (5%). A paternal age above 35 years at the time of child’s birth was present in 7 cases (35%). Paternal exposure to occupational heat was noted in 6 cases (30%) and parental exposure to chemicals in 3 cases (15%). All cases showed typical clinical and radiological manifestations of achondroplasia. Anthropometricmeasurements quantitatively confi rmed the body physique in thestudied cases. G380R common mutations of the FGFR3 gene were detected in 15/18 cases (83%) with the G to A transition at nucleotide 1138 in 14 cases (77%). Agenesis of corpus callosum, not previously reported in association with achondroplasia, was present in the only case with the G-C transversio nmutation at nucleotide 1138 (5%).Conclusions: Awareness of the cardinal features of achondroplasia, properanthropometric measurements and detailed skeletal survey are the key foraccurate diagnosis, genetic counseling and avoidance of over diagnosis. The majority of studied Egyptian achondroplasia patients have the same common mutation that has been most often defi ned in patients with achondroplasia from other countries.Keywords: Achondroplasia, fi broblast growth factor receptor3,skeletal dysplasia, paternal heat exposure

Combination of Human Amniotic Fluid Derived-Mesenchymal Stem Cells and Nano-hydroxyapatite Scaffold Enhances Bone Regeneration

BACKGROUND: Human amniotic fluid-derived stem cells (hAF-MSCs) have a high proliferative capacity and osteogenic differentiation potential in vitro. The combination of hAF-MSCs with three-dimensional (3D) scaffold has a promising therapeutic potential in bone tissue engineering and regenerative medicine. Selection of an appropriate scaffold material has a crucial role in a cell supporting and osteoinductivity to induce new bone formation in vivo. AIM: This study aimed to investigate and evaluate the osteogenic potential of the 2nd-trimester hAF-MSCs in combination with the 3D scaffold, 30% Nano-hydroxyapatite chitosan, as a therapeutic application for bone healing in the induced tibia defect in the rabbit. SUBJECT AND METHODS: hAF-MSCs proliferation and culture expansion was done in vitro, and osteogenic differentiation characterisation was performed by Alizarin Red staining after 14 & 28 days. Expression of the surface markers of hAF-MSCs was assessed using Flow Cytometer with the following fluorescein-labelled antibodies: CD34-PE, CD73-APC, CD90-FITC, and HLA-DR-FITC. Ten rabbits were used as an animal model with an induced defect in the tibia to evaluate the therapeutic potential of osteogenic differentiation of hAF-MSCs seeded on 3D scaffold, 30% Nano-hydroxyapatite chitosan. The osteogenic differentiated hAF-MSCs/scaffold composite system applied and fitted in the defect region and non-seeded scaffold was used as control. The histopathological investigation was performed at 2, 3, & 4 weak post-transplantation and scanning electron microscope (SEM) was assessed at 2 & 4 weeks post-transplantation to evaluate the bone healing potential in the rabbit tibia defect. RESULTS: Culture and expansion of 2nd-trimester hAF-MSCs presented high proliferative and osteogenic potential in vitro. Histopathological examination for the transplanted hAF-MSCs seeded on the 3D scaffold, 30% Nano-hydroxyapatite chitosan, demonstrated new bone formation in the defect site at 2 & 3 weeks post-transplantation as compared to the control (non-seeded scaffold). Interestingly, the scaffold accelerated the osteogenic differentiation of AF-MSCs and showed complete bone healing of the defect site as compared to the control (non-seeded scaffold) at 4 weeks post-transplantation. Furthermore, the SEM analysis confirmed these findings. CONCLUSION: The combination of the 2nd-trimester hAF-MSCs and 3D scaffold, 30% Nano-hydroxyapatite chitosan, have a therapeutic perspective for large bone defect and could be used effectively in bone tissue engineering and regenerative medicine

Osteogenic Differentiation Potential of Human Bone Marrow and Amniotic Fluid-Derived Mesenchymal Stem Cells in Vitro & in Vivo

BACKGROUND: Cell therapies offer a promising potential in promoting bone regeneration. Stem cell therapy presents attractive care modality in treating degenerative conditions or tissue injuries. The rationale behind this is both the expansion potential of stem cells into a large cell population size and its differentiation abilities into a wide variety of tissue types, when given the proper stimuli. A progenitor stem cell is a promising source of cell therapy in regenerative medicine and bone tissue engineering. AIM: This study aimed to compare the osteogenic differentiation and regenerative potentials of human mesenchymal stem cells derived from human bone marrow (hBM-MSCs) or amniotic fluid (hAF-MSCs), both in vitro and in vivo studies. SUBJECTS AND METHODS: Human MSCs, used in this study, were successfully isolated from two human sources; the bone marrow (BM) and amniotic fluid (AF) collected at the gestational ages of second or third trimesters. RESULTS: The stem cells derived from amniotic fluid seemed to be the most promising type of progenitor cells for clinical applications. In a pre-clinical experiment, attempting to explore the therapeutic application of MSCs in bone regeneration, Rat lumbar spines defects were surgically created and treated with undifferentiated and osteogenically differentiated MSCs, derived from BM and second trimester AF. Cells were loaded on gel-foam scaffolds, inserted and fixed in the area of the surgical defect. X-Ray radiography follows up, and histopathological analysis was done three-four months post- operation. The transplantation of AF-MSCs or BM-MSCs into induced bony defects showed promising results. The AF-MSCs are offering a better healing effect increasing the likelihood of achieving successful spinal fusion. Some bone changes were observed in rats transplanted with osteoblasts differentiated cells but not in rats transplanted with undifferentiated MSCs. Longer observational periods are required to evaluate a true bone formation. The findings of this study suggested that the different sources; hBM-MSCs or hAF-MSCs exhibited remarkably different signature regarding the cell morphology, proliferation capacity and osteogenic differentiation potential CONCLUSIONS: AF-MSCs have a better performance in vivo bone healing than that of BM-MSCs. Hence, AF derived MSCs is highly recommended as an alternative source to BM-MSCs in bone regeneration and spine fusion surgeries. Moreover, the usage of gel-foam as a scaffold proved as an efficient cell carrier that showed bio-compatibility with cells, bio-degradability and osteoinductivity in vivo