Reduced-order Models of Power Systems based on Controllability and Observability

Reduced-order models for dynamic control of power systems are formulated using a modal analysis technique, based on the notion of controllability and observability. In this technique, an input/ouutput index is used to identify and rank the strongly controllable and observable modes of the system given a particular input/output pair. The system state variables that are strongly related to the retained modes are then determined by analysis of a participation factor martrix. Davison's method of reducing linear systems is then applied to formulate the desired reduced order dynamic equivalent. This technique of forming dynamic equivalents is investigated on a single machine infinite bus system. Several reduced order model equivalents are formed and evaluated on their performance and accuracy

Hepcidin and iron status in chronic kidney disease

Hepcidin is a critical inhibitor of iron export frommacrophages, enterocytes, and hepatocytes. Given that itis filtered and degraded by the kidney, its elevated levelsin renal failure have been suggested to play a role in thedisordered iron metabolism of uremia. It is a smalldefensin-like peptide whose production by hepatocytes ismodulated in response to anemia, hypoxia, orinflammation. Hepcidin could also act as an indicator offunctional iron deficiency (FID) in chronic kidneydisease (CKD) patients. This study was performed toassess hepcidin and its correlations with renal function,iron status parameters {serum iron, serum ferritin,transferrin saturation (TSAT) and soluble transferrinreceptor (sTfR)}, inflammatory cytokines (IL-6&IFN-?)and inflammatory markers (CRP) in patients with CKDeither on conservative treatment or on maintenancehemodialysis (HD). Serum prohepcidin was higher inHD patients compared to controls and CKD patients. Inthe whole patient group, serum hepcidin correlatedsignificantly with hemoglobin (Hb), IL-6, creatinine,CRP, sTfR and urinary hepcidin. In HD groupprohepcidin correlated significantly with creatinine.Multiple regression analysis showed that prohepcidinwas most predicted by serum creatinine and CRP.Elevated prohepcidin levels in HD patients studied couldmainly be due to its accumulation in impaired renalfunction in addition to low-grade inflammation,frequently encountered in this population

Endogenous chemical exchange saturation transfer (CEST) MR imaging for the diagnosis and therapy response assessment of brain tumors: A systematic review

Purpose: To generate a narrative synthesis of published data on the use of endogenous chemical exchange saturation transfer (CEST) MR imaging in brain tumors. Materials and Methods: A systematic database search (PubMed, Ovid Embase, Cochrane Library) was used to collate eligible studies. Two researchers independently screened publications according to predefined exclusion and inclusion criteria, followed by comprehensive data extraction. All included studies were subjected to a bias risk assessment using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Results: The electronic database search identified 430 studies, of which 36 studies fulfilled the inclusion criteria. The final selection of included studies was categorized into 5 groups as follows: grading gliomas, 19 studies (areas under the curve (AUC) 0.500-1.000); predicting molecular subtypes of gliomas, 5 studies (AUC 0.610-0.920); distinction of different brain tumor types, 7 studies (AUC 0.707-0.905); therapy response assessment, 3 studies (AUC not given) and differentiating recurrence from treatment-related changes, 5 studies (AUC 0.880- 0.980). A high bias risk was observed in a substantial proportion of studies. Conclusion: Endogenous CEST imaging offers valuable, potentially unique information in brain tumors, but its diagnostic accuracy remains incompletely known. Further research is required to assess the method’s role in support of molecular genetic diagnosis, to investigate its use in the post treatment phase, and to compare techniques with a view to standardization

Determination of Hydrazlne Using Potassium Dichromate as Oxidizing Agent

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Synthesis And Characterization Of PVP Based Catalysts For Selected Application In Catalysis

This research aims to study the catalyst activity in specific reactions and the characteristics of the catalyst in order to optimize its performance. This research investigates PVP based catalysts and their properties and applications. PVP was prepared in combination with different metal oxides in order to be tested for different catalytic applications including dye removal. Methyl orange was used as a dye and different concentrations were tested against different metallic ions in order to optimize the catalyst for being used in dye removal applications. Spectrophotometer was used to calculate the concentration of the dye before and after catalyst exposure and investigate the relation between contact time and concentrations. Applying different contact time to the same weight percent of PVP based catalyst with metallic ions revealed that increasing the contact time with a good shaking lead to decrease in the concentration of the dye mixed with the sample. The tests showed that the mixture between PVP and Nickel has the best dye removal within the other metal ions (copper and ferric) as well it showed that ferric has the least effect on dye removal. Wide angle x-ray diffraction (WA-XRD) was applied to different sample copper with PVP and ferric with PVP

Performance Measure Of Industrial Robotics In Lean Enterprise: A Case Study In Semiconductor Industry

Industrial robotics replaced human workers in almost all fields due to their abilities to multitask, flexibility and configurability in any position they involved in. However, implementing industrial robotics is challenging due to their high cost, expert handling, and complexity. The object of this study is to determine the performance measurement using the QCDAC method or (quality, cost, delivery, accountability and continual improvement) then categorized according to lean principles and then identifying seven main areas that the industrial robotics contributes in the semi-conductor company. The performance identification and ranking is done by using Interpretive Structural Modelling (ISM) methodology to identify the most affected performance of the model and to clarify the industrial robotics performance in these areas in which the industrial robotics fit and compatible with the lean enterprise. Human- robot interaction considered to guarantee the workers' safety working alongside industrial robotics. The result of the ISM method shows the performance measure that affects the industrial robotics to support lean enterprise in terms of quality improvement, cost reduction and efficiency

Microwave Assisted Synthesis Of Binary Metallic Oxides For Catalysis Applications

Herein, versatile, and reproducible method to prepare binary metal oxides via microwave assisted synthesis. Catalysts are substances that basically speeds up chemical reactions. Ideally, bonds are formed between the catalysts and the reactants. Also, catalysts permit formation of products from the reactants. These formed products, splits off the catalyst without affecting or changing it. Catalytic kinetics studies the correlate chemical reaction rate with some properties of reactants and/or products for instance, temperature, concentration and pressure. The aim of the project is to prepare pure and bi-metal iron-based catalyst by co-precipitation method and to characterize the prepared sample using X-ray diffraction. Metal oxides nanoparticles is a field of interest in catalysis, such that these oxides are used to oxidize carbon monoxide. The samples were prepared through co-precipitation method in laboratory scale. The metals used was copper, iron and cobalt. After preparing pure sample of each metal a mix of two metals were introduced in different ratios. The samples were characterized via X-ray diffraction (XRD) and then the results were compared to exist data introduced from others research, the prepared samples XRD was having a great matching with the data retrieved from internet and we found that the metal could exist in two form of oxides and even could exist as pure metal. Each peak in the XRD figure could indicate one or more phase of the metal

Generating optical orbital angular momentum at visible wavelengths using a plasmonic metasurface

The authors acknowledge the support of the Canada Excellence Research Chairs Program.Light beams with a helical phase-front possess orbital angular momentum along their direction of propagation in addition to the spin angular momentum that describes their polarisation. Until recently, it was thought that these two ‘rotational’ motions of light were largely independent and could not be coupled during light–matter interactions. However, it is now known that interactions with carefully designed complex media can result in spin-to-orbit coupling, where a change of the spin angular momentum will modify the orbital angular momentum and vice versa. In this work, we propose and demonstrate that the birefringence of plasmonic nanostructures can be wielded to transform circularly polarised light into light carrying orbital angular momentum. A device operating at visible wavelengths is designed from a space-variant array of subwavelength plasmonic nano-antennas. Experiment confirms that circularly polarised light transmitted through the device is imbued with orbital angular momentum of ±2ħ (with conversion efficiency of at least 1%). This technology paves the way towards ultrathin orbital angular momentum generators that could be integrated into applications for spectroscopy, nanoscale sensing and classical or quantum communications using integrated photonic devices.Publisher PDFPeer reviewe