S-parameter based technique for simultaneous switching noiseanalysis in electronic packages

A method based on S-parameters is developed for the analysis of simultaneous switching noise (SSN) in electronic packages. A two-port Z matrix of the package pin/trace, and the coupling between the pins/traces are modeled by analytical equations. SSN is analyzed as a function of the number of switching drivers and switching time. Frequency domain measurements are performed to demonstrate the accuracy of the model. The modeling methodology is applied to both leaded and area array packages     

An improved prediction of series resistance in spiral inductormodeling with eddy-current effect

Based on an earlier study by Kuhn and Ibrahim (see IEEE J. Trans. Microwave Theory Tech., vol. 49, no. 1, p. 31-38, 2001) on current crowding, an improved expression incorporating the skin effect for the prediction of series resistance in spiral inductor modeling has been derived. A modified model for the spiral inductor, which accounts for the eddy-current effect, is thus proposed. Relatively good agreements between the measured data and the results generated from the model are obtained     

A dual-mode bandpass filter with enhanced capacitive perturbation

A dual-mode ring bandpass filter with two pairs of capacitors has been designed. The capacitors are used to control the location of the even- and odd-mode frequencies independently, allowing weak coupling for narrow-band filter design with realizable capacitance values. Theoretical expressions have been derived for these frequencies. A 4% bandwidth bandpass filter centered at 1.9 GHz was designed and tested with good agreement between theoretical and measured results.     

Unambiguously Enhanced Ultraviolet Luminescence of AlGaN Wavy Quantum Well Structures Grown on Large Misoriented Sapphire Substrate

High‐quality epitaxy consisting of Al_1?xGa_xN/Al_1?yGayN multiple quantum wells (MQWs) with sharp interfaces and emitting at ≈280 nm is successfully grown on sapphire with a misorientation angle as large as 4°. Wavy MQWs are observed due to step bunching formed at the step edges. A thicker QW width accompanied by a greater accumulation of gallium near the macrostep edge than that on the flat‐terrace is observed on 4° misoriented sapphire, leading to the generation of potential minima with respect to their neighboring QWs. Consequently, a significantly enhanced photoluminescence intensity (at least ten times higher), improved internal quantum efficiency (six times higher at low excitation laser power), and a much longer carrier lifetime are achieved. Importantly, the wafer‐level output‐power of the ultraviolet light emitting diodes on 4° misoriented substrate is nearly increased by 2–3 times. This gain is attributed to the introduction of compositional inhomogeneities in AlGaN alloys induced by gallium accumulation at the step‐bunched region thus forming a lateral potential well for carrier localization. The experimental results are further confirmed by a numerical modeling in which a 3D carrier confinement mechanism is proposed. Herein, the compositional modulation in active region arising from the substrate misorientation provides a promising approach in the pursuit of high‐efficient ultraviolet emitters.     

Unity PF current-source rectifier based on dynamic trilogic PWM

One remaining step in perfecting the stand-alone, unity power factor, regulated current-source pulse-width-modulated (PWM) rectifier is to reduce cost, by bringing the twelve-valve converter (consisting of three single-phase full bridges that operate with two-level or bilogic PWM) to the six-valve bridge. However, the six-valve topology requires a three-level or trilogic PWM strategy that can handle feedback signals. A general method of translating three-phase biologic PWM signals into three-phase trilogic PWM signals is presented. The method of translation retains the characteristics of the bilogic PWM, including the frequency bandwidth. Experiments show that the trilogic PWM signals produced by the method can handle not only stabilizing feedback signals but also signals for active filtering     

Exploiting the Plackett–Burman design to examine the formulation effect on curing characteristics of oil palm ash-filled acrylonitrile butadiene rubber compounds

The present paper is focused on exploiting Plackett–Burman design to examine the formulation effect of various chemical components content on the curing characteristics of oil palm ash (OPA)-filled acrylonitrile butadiene rubber (NBR) compound. The filled-NBR compound was prepared by conventional laboratory-sized two roll mill and cured using sulfuric system. Six independent variables such as content of zinc oxide, stearic acid, N-isopropyl-N′-phenyl-p-phenylenediamine, N-cyclohexyl-2-benzothiazole sulfenamide (CBS), sulfur, and even OPA filler were carried out to screen their significant effect on the curing characteristics of NBR compound. The scorch time, optimal cure time, minimum torque, and maximum torque were selected as a response. Results showed that the scorch time and the optimal cure time were significantly affected by CBS, whereas the minimum torque and maximum torque were significantly affected by OPA and sulfur, respectively, within the studied range. Among the chemical components under study, zinc oxide and stearic acid had the least effect on the curing properties of NBR compound. Analysis of variances for all factorial models demonstrated that the model was significant with P value <0.05 while the regularity (R ²) of all models was greater than 0.9. Lastly, the optimal chemical concentrations were predicted to acquire the optimal condition of the curing system for filled-NBR compound.     

Multiple-wavelength integration in InGaAs-InGaAsP structures using pulsed laser irradiation-induced quantum-well intermixing

In this paper, we present the characteristics of a quantum-well intermixing technique using pulsed-photoabsorption-induced disordering. Photoluminescence, micro-Raman spectroscopy, and transmission electron microscopy were used to characterize the process. Using this technique, a differential wavelength shift between the intermixed and nonintermixed regions of over 160 nm has been observed from InGaAs-InGaAsP heterostructures. It was found from the micro-Raman measurements that a spatial resolution of better than 2.5 /spl mu/m can be achieved. A theoretical model has been developed to estimate the spatial resolution limit. Theoretical analysis has also been performed to investigate the effect of laser irradiation on the degree of intermixing in InGaAs-InGaAsP structures. To verify the capability of this process in monolithic photonic integration, high-quality bandgap tuned lasers, two-section extended cavity lasers, and multiple-wavelength laser chips have been fabricated.     

Asymmetric organocatalysis of structurally well-defined chiral quaternary ammonium fluorides

Unique organocatalysis of both naturally occurring cinchona alkaloid-derived and purely synthetic chiral quaternary ammonium fluorides in synthetically useful stereoselective bond-forming reactions is overviewed. The development of this chemistry was initiated by the in situ generation of generally hygroscopic ammonium fluorides from the corresponding easy-to-handle ammonium salts in the presence of excess metal fluorides and their direct use for subsequent enantioselective reactions. On the other hand, chiral ammonium fluorides have been prepared by using ion-exchange resins and successfully applied as catalyst to various asymmetric bond formation reactions under homogeneous conditions. In addition, utilization of chiral quaternary ammonium bifluorides as organocatalysts in asymmetric synthesis is described, featuring their characteristic reactivity and selectivity.     

Planning of carbon capture and storage with pinch analysis techniques

Carbon capture and storage (CCS) is a means for reducing carbon dioxide (CO₂) emissions from fossil fuel combustion in power generation and industrial processes. It involves the capture of CO₂ for subsequent storage in various geological formations. The selection and matching of the power plants and storage sites are often an issue of optimisation due to various constraints, i.e., time of availability, injection rate, and storage capacity limits. In this work, a novel graphical targeting tool based on pinch analysis is proposed to address the planning problem of the storage of captured CO₂ from power generating plants into corresponding reservoirs. The main consideration for the problem is the time of availability of the latter, since reservoirs need to be developed prior to CO₂ storage. The time limitation is addressed by the graphical technique where time is taken as the governing element in solving the problem. Hypothetical examples are used to elucidate the proposed approach.