Design procedure for reduced filter size in a buck converter using a 4th-order resonance filter

This article presents a novel design procedure for 4th order and 4th order resonance (4thRes) output filters, for given buck converter specifications, making components selection a straightforward process. An accurate filter analysis is provided to predict the filter component currents and voltages in both frequency and time domains. Application of the analysis in a design study of a 20 MHz, 5.4 W buck converter shows that the 4thRes filter has the potential to reduce the output passive components for a wide duty cycle range. As compared with a 2nd order filter at V IN = 6.6 V to V OUT = 1.8 V, total inductance, inductor energy, capacitance, and capacitor energy are 58%, 35%, 45%, and 31% lower, respectively. Air-core PCB integrated solenoid inductors are considered for implementation and testing within a prototype converter to show the impact of these filters on the converter performance. The 4thRes filter achieved 3.7% and 3.6% higher full-load efficiency than the 2nd and 4th order filters, respectively, and a better load transient performance

Analytical expressions for inductances of 3D air core inductors for integrated power supply

This work presents analytical expressions for the DC inductance of 3D air core inductors with circular cross section pillars (CCSP) and rectangular cross section pillars (RCSP). We consider the following four types of inductor structures: (1) a toroid with CCSP; (2) a toroid with RCSP; (3) a solenoid with RCSP; and (4) a solenoid with CCSP. For each type, a unique analytical model is developed for obtaining DC inductance. High frequency (1-100 MHz) effects on inductance are also discussed. The inductance values predicted by the proposed analytical models of the first three types of inductor structures are in an acceptable agreement with numerical Finite Element Analysis (FEA) solutions, where the maximum difference is 7.3%. Also, our analytical model for the fourth type inductor reduces the error, when correlated with FEA inductance value, up to 6× compared to previously published models. A comparison of results using proposed analytical expressions with published measured values as well as our measurement data demonstrates error ranging from 0.5 to 16.2%, while conventional formulae show errors of up to 143%. The results of the proposed models could serve as a good initial estimate for power supply on chip (PwrSoC) and power supply in package (PSiP) applications

Reactions of 5-Aroylmethylene-3-benzyl-4-oxo-2-thioxo-1,3-thiazolidines with Nitrile Oxides

E,Z-5-Aroylmethylene-3-benzyl-4-oxo-2-thioxo-1,3-thiazolidines (3a-c) react with 4-methoxy and 4-chlorophenylnitrile oxides (4a and b) in pyridine solution to afford one or more of the following compounds: Z-3, Z-2,4-dioxo analogues 5 and 3,6-diaryl-1,4,2,5-dioxadiazines (6a-b). The interconversion route is discussed and the structures of all of the synthesised compounds are proven by microanalytical and spectral data

The Mubarak Regime's Failed Youth Policies and the January Uprising

Throughout its 30 years in power, the regime of President Mubarak failed to meet the needs of the younger generation. During the last ten years in particular, the gap between actual reality and the political rhetoric about empowering the young and allowing them to better their lives grew steadily. The regime failed to embrace a public policy for the youth that would be binding on all state institutions. It could not come up with clear goals in education, employment and political initiation. The considerable funding that went into improving the output of the educational process and creating jobs for the youth did not change this reality. Meanwhile, the National Democratic Party (NDP) placed unrealistic hopes on the commitment and loyalty of its young members, whose failure to support the regime became clear during the January 25th uprising. The regime's focus was on activities aimed to fill the time of young people, rather than on political activities that were open to all young people, regardless of their political and intellectual affiliations

Synthesis and antitumor activity evaluation of some novel pyrazolotriazine derivatives

<p>6-Aminopyrazolo[1,2-<i>a</i>][1,2,4]triazine-4,8-dione derivative <b>3</b> was obtained upon the reaction of the acid hydrazide derivative <b>2a</b> with ethyl cyanoacetate. The reactions of <b>3</b> with several electrophiles such as aldehydes, isatin, acetic anhydride, phenyl isocyanate, benzoyl isothiocyanate, and <i>p</i>-toluenesulfonyl chloride were studied. The structures of the newly synthesized compounds were established on the basis of IR, ¹H NMR, mass spectra, and elemental analyses. The antitumor activities of some selective compounds were examined against two cell lines as liver carcinoma cell line (HEPG-2) and human breast cancer cell line (MCF7).</p