A New Symmetric/Asymmetric Multilevel Inverter Based on Cascaded Connection of Sub-Multilevel Units Aiming less Switching Components and Total Blocked Voltage

In this paper, a new multilevel inverter is designed to improve the power and voltage quality, which contains a lesser number of switches in the specified voltage levels. The proposed inverter includes power electronic devices such as switches and diode, and DC inputs. In the proposed structure the desired output voltage can be produced by considering a series connection of a novel sub-multilevel module. This structure can be designed in both the symmetric and asymmetric topologies. The proposed structure has superior condition in terms of semiconductor switches and drivers count as well as switching loss. Additionally, the Total Blocked Voltage (TBV) of the proposed converter is compared with the conventional and the novel converters. This topology is studied by symmetric as well as asymmetric topologies through simulations in Matlab/Simulink environment as well as experiments by a laboratory prototype

Three-Dimensional Simulation of Turbulent Hot-Jet Ignition for Air-CH4-H2 Deflagration in a Confined Volume

This work describes essential aspects of the ignition and deflagration process initiated by the injection of a hot transient gas jet into a narrowly confined volume containing air-CH4-H2 mixture. Driven by the pressure difference between a prechamber and a long narrow constant-volume-combustion (CVC) chamber, the developing jet or puff involves complex processes of turbulent jet penetration and evolution of multi-scale vortices in the shear layer, jet tip, and adjacent confined spaces. The CVC chamber contains stoichiometric mixtures of air with gaseous fuel initially at atmospheric conditions. Fuel reactivity is varied using two different CH4/H2 blends. Jet momentum is varied using different pre-chamber pressures at jet initiation. The jet initiation and the subsequent ignition events generate pressure waves that interact with the mixing region and the propagating flame, depositing baroclinic vorticity. Transient three-dimensional flow simulations with detailed chemical kinetics are used to model CVC mixture ignition. Pre-ignition gas properties are then examined to develop and verify criteria to predict ignition delay time using lower-cost non-reacting flow simulations for this particular case of study

Clinical Validation of a Dried Blood Spot Assay for 8 Antihypertensive Drugs and 4 Active Metabolites

BACKGROUND: Drug nonadherence is one of the major challenges faced by resistant hypertension patients, and identification of this problem is needed for optimizing pharmacotherapy. Dried blood spot (DBS) sampling is a minimally invasive method designed to detect and determine the degree of nonadherence. In this study, a DBS method for qualifying 8 antihypertensive drugs (AHDs) and 4 active metabolites was developed and validated using ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). METHOD: The DBS assay was validated analytically and clinically, in accordance with FDA requirements. Analytical validation was accomplished using UHPLC-MS/MS. For clinical validation, paired peak and trough levels of DBS and plasma samples were simultaneously collected and comparatively analyzed using Deming regression and Bland-Altman analyses. All concentrations below the set lower limit were excluded. Deming regression analysis was used to predict comparison bias between the collected plasma and DBS samples, with DBS concentrations corrected accordingly. RESULTS: The UHPLC-MS/MS method for simultaneously measuring 8 AHDs and their metabolites in DBS, was successfully validated. With Deming regression no bias was observed in N = 1; constant bias was seen in N = 6 and proportional bias in N = 11 of the AHDs and metabolites. After correction for bias, only one metabolite (canrenone) met the 20% acceptance limit for quantification, after Bland-Altman analyses. In addition, amlodipine, valsartan, and [enalaprilate] met the 25% acceptance limit. CONCLUSIONS: A novel DBS assay for simultaneously qualifying and quantifying 8 AHDs and their metabolites, has been successfully developed and validated. The DBS assay is therefore a suitable method to detect drug nonadherence. However, with the exception of canrenone, the interchangeable use of plasma and DBS sa

Flame Retardant Hybrid System of Triphenyl Phosphate/Nanoclay in Evaluation of Flammability and Mechanical Properties of PC/ABS Compound

Nanoclay/triphenyl phosphate hybrid system was employed to examine the fire retardancy and mechanical properties of PC/ABS blends. Each of the polymers and their blends are widely used in the automotive, electrical andelectronic industries. Because most thermoplastics are easily combustible they need to be flame retarded to reduce the burning rate especially in the initial phase of a fire incident. The effect of nanoclay on the fire resistance of nanocomposites has been the subject of many research works. Nanosize clay particles improve the fire performance of composites with no significant effect on the ignition ability and extinguishing time. The improvement in flame retardancy of composites has been observed only when nano size species are present with conventional flame retardant additives. Such combinations may result in either a desired level of flame retardancy lower than the normal conventional level with matrix property retention. In this study, the samples were prepared via a direct melt blending process in a twin-screw extruder, and the processing temperature was set at 200-250oC. The effects of nanoclay/triphenyl phosphate hybrid system on the fire retardancy of PC/ABS blend were assessed by cone calorimetry, LOI (Limited Oxygen Index) and UL94 (Underwriters Laboratories), and tensile and impact properties of the composites were determined. The synergistic effect of nanoclay on flame retardancy of TPP has been observed from the fire test and the mechanical properties were improved

Saponification then GC for determination of Irganox 1010 and Irganox 1076 in a polymer matrix

A gas chromatographic method has been established for determination of Irganox 10 10 and 1076 after saponification. The analytes were saponified with methanolic potassium hydroxide, acidified with hydrochloric acid, and the solvent was removed by rotary evaporation. The dry residue was dissolved in xylene and analyzed by GC with flame-ionization detector (FID). Compounds were separated on a polar (Carbowax 20 M) capillary column and nitrogen was used as carrier gas and make-up gas. This method has a relatively large linear dynamic range, 50-3,000 and 100-1,600 mg L-1 for Irganox 1010 and 1076, respectively, and limits of detection (LOD) were 20 and 40 mg L-1, respectively. The effect of conditions such as saponification temperature, and concentration and volume of potassium hydroxide were studied