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This study applies algebraic polynomials to investigate the effects of independent dimensionless parameters on the shape of an isolated pore resulting from a bubble completely entrapped by a solidification front. The pore shape in solid is contemporarily challenging in controlling directional properties of natural or functional materials in MEMS, packaging, manufacturing and medical and micro-or nano-technologies. In this work, polynomials with different degrees are provided by extending previous work, accounting for conservation of total solute content in the pore and boundary layer on the bubble cap, on which solute transport in different directions, balance of pressures and physico-chemical equilibrium are satisfied. Dimensionless independent parameters include product of Bond number with initial liquid concentration, solidification rate, mass transfer coefficient, Henry’s law constant, atmospheric pressure, and initial contact angle. By comparison with numerical solutions of thermal fluid and concentration equations, it is found that Cases 1 and 2 referred to different mass transfer coefficients and directions of solute transport from the pore to surrounding liquid in the early stage are relevant, rather than available Cases 3 and 4 with different modeling of solute transfer rates. Polynomials with 4 and 5 degrees to predict shapes of the isolated pore are in good agreement with numerical solution of simultaneous first-order unsteady ordinary equations governing solute gas pressure and geometry of the pore and experimental data.

Fe-based amorphous metallic coatings (AMCs) were prepared by the activated combustion−high velocity air fuel (AC − HVAF) coating method. A micro/nanoscale hydrophobic surface based on the lotus effect was constructed on the AMCs by chemical etching and surface modification, and the controllable preparation of bionic hydrophobic structures was realized by optimizing the chemical etching time and etching concentration. The influence of surface treatment on the corrosion resistance of the coatings was analyzed by electrochemical testing, and the correlation between the hydrophobicity of the coating structure and its corrosion resistance was determined. Results showed that the surface of the hydrophobic AMCs is composed of micro/nanoscale hierarchical structures of synapses formed by unmelted particles and corrosion products. Several pores and pits were observed after chemical etching. As the chemical etching concentration and etching time increased, the solid−liquid contact fraction and surface energy of the hydrophobic AMCs first decreased and then increased. The water contact angle peaked at 142.52° when the coatings were chemically etched in 3 mol/L HCl solution for 60 min, thereby conforming to the Cassie−Baxter model. The passivation current density and pitting tendency of the hydrophobic AMCs in 3.5% NaCl solution were closely related to the chemical etching process. The prepared hydrophobic interface could form an effective air wall that isolates the coating surface from the corrosive medium and enhances its uniform corrosion resistance. However, chemical etching aggravated the pores and intensified the dissolution of inclusions, thereby increasing the pitting sensitivity of these concavities. The construction of robust and compact bionic hydrophobic interfaces is an effective approach to enhance the uniform corrosion resistance of AMCs.

The asymmetrical rolling (ASR) process with shear deformation is considered as a promising technology to adjust/improve through-thickness microstructure homogeneity and integrated properties of high-strength aluminium alloy plates. But the advantages may come with caveats that are the subject of our research. In this paper, the room-temperature low cycle fatigue properties and fracture behaviour of the ASR-ed AA7050 aluminium alloy plates are compared with the symmetrical rolling (SR) one. It is shown that after either type of rolling the plates exhibit similar low-cycle fatigue lives but the SR-ed one displays a better cyclic deformation ability and slightly higher fatigue lives at high strain amplitudes. It is demonstrated that the severe surface-localized deformation contributes to the formation of slip relief on the surface and subsequently initiates micro-cracks that are propagated via transgranular and/or intergranular fracture modes along with obvious fatigue striations. Recrystallised grains with coarse grain boundary precipitates and wide precipitate-free zones near the upper/bottom layers as well as numerous and larger secondary particles in the ASR-ed plates may cause early crack initiation for a short crack initiation life. However, the SR-ed plate with more frequent subgrains near surface layers, numerous fine subgrains and less indissoluble particles could possess better crack initiation/propagation resistance and cyclic loading behaviour. Fine subgrains with higher microhardness/strength can facilitate passing of dislocations or slip bands into adjacent grains so as to delay crack propagation such as via energy-intensified transgranular fracture for extending fatigue life. Properly balancing the through-thickness strain/deformation distribution and the formation of recrystallization/indissoluble particles via implementing a feasible ASR process becomes a critical issue to achieve fracture-resistant microstructures for high-strength aluminium alloy plates. The underlying causes/mechanisms regarding the differences of microstructures and mechanical behaviour are revealed and discussed based on modelling through-thickness temperature/strain distribution and detailed microstructure characterization.

TaNbSiZrCr high entropy alloy (HEA) coatings were deposited on WC substrates using a radio frequency (RF) unbalanced magnetron sputtering system. To explore the effects of nitrogen addition on the coating properties, the coatings were deposited with various nitrogen-to-argon ratios RNx (where x = N2/Ar and lies in the range of 0– 0.5). Furthermore, to examine the effects of heat treatment, half of the coatings were retained in an as-deposited condition, while the remainder were annealed at 750 °C for 60 min. The microstructures, mechanical properties and anti-sticking properties of the various coatings were evaluated and compared. The as-deposited coatings were all found to have an amorphous structure. By contrast, the annealed samples had a BCC structure at low RNx ratios (≤0.3), but a FCC structure at HRN0.5. All of the coatings showed excellent adhesion and mechanical properties in both the as-deposited condition and the annealed condition. The hardness of the as-deposited coatings increased with an increasing nitrogen content. However, the annealing process produced no significant change in the hardness. Moderate nitrogen addition (RNx ≤ 0.4) was found to be beneficial in preventing the adhesion of the HEA coating to the glass interface during simulated moulding tests. However, the RN0.5 coating showed a poor anti-glass-sticking performance due its columnar structure and high nitrogen content, which prompted a strong interfacial interaction. No significant change was observed in the surface energies of the coatings after the annealing process. Thus, it was inferred that all of the coatings had excellent thermal stability. Finally, the micro-drilling test results showed that the RN0.5 coating, with the highest hardness of all the coatings, improved the quality of the drilled holes and increased the micro-drill lifetime to more than 6000 holes; representing a three-fold improvement over that of an uncoated micro-drill.

This study shows that there exist the universal three phase diagrams to describe general development of the pore shape in solid, resulting from a bubble captured by a solidification front with different solidification rates. Pore formation and its shape strongly determine microstructural quality of materials, functional materials encountered in biology, chemistry, engineering, foods, and phenomena of geophysics and climate change, and so on. The solidification rate plays an important role in solute transport and gas pressure, contact angle of the bubble cap, and pore shape in solid. Three universal phase diagrams are under dimensionless coordinate systems of (1) solidification rate, temperature gradients in solid and liquid at the solidification front, (2) solidification rate, contact angle and growth rate of base radius of the cap, and (3) apex radius, contact angle and base radius of the cap. Solidification rate is determined by temperature gradients in liquid and solid at the solid-liquid interface governed by the Stefan boundary condition, whereas apex radius is determined by solute gas pressure in the pore governed by the Young-Laplace equation, equation of state, and different cases governing directions of mass transfer in the pore. Extending previous analysis, phase diagrams in this study confirm that the bubble cannot be completely entrapped in Case 2b, which represents a stronger effect of pore volume expansion on solute gas pressure than solute transport from the surrounding liquid to pore in the early stage. The computed and measured results of development of the pore shape are in good agreement.

In this study, the notched strengths of three kinds of braided composite plates with a center hole were investigated. Both point stress criterion (PSC) and average stress criterion (ASC) were first applied to find the characteristic length of each braided composite plate with different sizes of the hole. It was found that the characteristic lengths predicted by both criteria are not constants. Based on the concept of three-parameter criterion, the characteristic lengths obtained by both criteria were then proposed to be expressed as functions of hole size as well as width of the plate. The notched strength of braided composite plates was then predicted. Finally, it was shown that both modified PSC and modified ASC gave better predictions of the notched strength than traditional PSC and ASC for all the kinds of braided composite plates.

CHANG Y.H., LI H.-H., WU C.M. & WANG P.C. (2010) The influence of personality traits on nurses' job satisfaction in Taiwan. International Nursing Review Aim: The purpose of this study was to empirically investigate a set of personality traits based on core self-evaluations in relation to job satisfaction among nurses in Taiwan, and to identity important personality characteristics in contributing to nurses' satisfactory attitudes towards work. Method: A cross-sectional survey research was conducted with self-reported questionnaires. The participants were 314 nurses (89% response rate) in two regional hospitals in Taiwan. Among them, 99% were female (n = 311), 54.5% (n = 171) ranging between 21 and 30 years old, 37.9% (n = 119) ranging between 31 and 40 years old, 44.6% (n = 140) are registered nurse, 29.3% (n = 92) are licensed vocational nurse and 52.9% were married (n = 166). In addition, ethical research requirements for conducting research on human subjects were fulfilled for all of the participants in the study. Analysis: Data were analysed using SPSS version 14.0 software (SPSS Inc., Chicago, IL, USA). A number of data analysis procedures were conducted including descriptive statistics, Pearson product-moment correlation and multiple regression analysis. The selection of the predictor variables was performed with the level of significance P

In this work, proton induced X-ray emission (PIXE) method was applied for the analysis of ancient Chinese Changsha porcelain produced in the Tang dynasty (AD 618–907). A collection of glazed potsherds was obtained in the complex of the famous kiln site at Tongguan, Changsha city, Hunan province. Studies of elemental composition were carried out on ten selected Changsha potsherds. Minor and trace elements such as Ti, Mn, Fe, Co, Cu, Rb, Sr, and Zr in the material of the porcelain glaze were determined. Variation of these elements from sample to sample was investigated. Details of results are presented and discussed.

Reflection and transmission of the energy of a transient elastic extensional wave at a sharp or smooth bend of a bar are studied theoretically and experimentally, with the principal aim being to validate the model used by Wu and Lundberg in a parallel study of harmonic elastic waves. In this model effects of rotary inertia and shear deformation are neglected, and in the straight sections before and after the bend the motion is assumed to be governed by the one-dimensional wave equation for extensional waves and the Euler –Bernoulli equation for flexural waves. Interest is focused on extensional waves mainly because there is a simple way to evaluate the energy of such waves from measurements of strains. Good agreement is obtained between experimental and theoretical results for energy transmission and reflection coefficients as well as for wave forms when (i) the incident wave is long relative to the transverse dimensions of the bar and (ii) the radius of curvature is either large relative to the transverse dimensions of the bar or small relative of the length of the incident wave.

Harmonic elastic waves in a uniform bar with a semi-infinite straight input section, a bend with constant radius of curvature, and a semi-infinite straight output section are considered, with the e ...

Summary Wave propagation and efficiency in percussive rock drilling with a bent rod is studied theoretically using a combined approach of FFT and matrix method. The bent drill rod is represented by straight uniform elements. The extensional and flexural stress waves in the drill rod are described by the one-dimensional wave equation and by Euler-Bernoulli theory, respectively. The conditions at the bit and rock during loading are represented by a penetration resistance, a lateral stiffness and a rotational stiffness. Numerical results are given for two cases; the first involves a drill rod with a constant radius of curvature through a certain bend angle, and the second a drill rod with a sharp bend defined by the same bend angle. It is found that for slightly bent rods the efficiency is practically the same as for straight rods. Thus, slight bends, which are always present in real drill rods, do not appear to be significant from the point of view of efficiency. Furthermore, it is found that the efficiency can remain high even if the rod is significantly bent. Thus, percussive rock drilling systems with special designs for drilling in curved paths are feasible from the point of view of efficiency.

A high performance 22/20nm CMOS bulk FinFET achieves the best in-class N/P I on values of 1200/1100 µA/µm for I off =100nA/µm at 1V. Excellent device electrostatic control is demonstrated for gate length (L gate ) down to 20nm. Dual-Epitaxy and multiple stressors are essential to boost the device performance. Dual workfunction (WF) with an advanced High-K/Metal gate (HK/MG) stack is deployed in an integration-friendly CMOS process flow. This dual-WF approach provides excellent V th roll-off immunity in the short-channel regime that allows properly positioning the long-channel device V th . Enhanced 193nm immersion lithography has enabled the stringent requirements of the 22/20nm ground rules. Reliability of our advanced HK/MG stack is promising. Excellent SRAM static noise margin at 0.45V is reported.

A methodology based on Taguchi methods was implemented to determined/optimize robot process capability (RPC) for path following. The methodology consists of the characterization of the robot path data, the experimental design, the data analysis procedure, and the verification of the results. Four figures of merit (FOMs) for accuracy and four FOMs for repeatability were used to characterize a robot's controlled path capability. The experiment considered seven controllable factors (i.e. load, speed, shape, size, direction, orientation, and height) and used an L 27 (3 13 ) orthogonal array. From the results of the data analysis, the optimal factor-level combinations for the best path capability and minimum process variation were determined. The experimental runs were verified. The recommended methodology has the advantages of cost effectiveness, efficiency, data compression, and flexibility.

Preliminary results from a simulation of the electric and magnetic form factors of the proton and neutron are described. We work on a quenched 16 3 ×24 lattice at β =6.0 with Wilson fermions using a technique that treats the zero momentum nucleon field as a secondary source.

We use the variational cumulant expansion method to study the four-dimensional lattice Z(2) gauge theory coupled to a radially varied scalar field which is assumed to take discrete values. Its phase structure is given in different cases. The comparison with the results from other approaches is also presented.

In this work, the design criteria of ECP additives on Cu BEOL reliability are revealed. By varying the ECP additive structures and concentrations, we demonstrate how gap filling performance and impurity level of the bulk copper can influence the electromigration lifetime and stress induced void (SIV) formation. It was found that the impurity in the grain boundary could act as an effective vacancy diffusion barrier to inhibit SIV formation. However, ECP additive conditions that produce highly impure Cu was found to increase the gap filling pits on top of the sub-micron features that would reduce the electromigration (EM) lifetime performance. By proper design of ECP additives, high impurity incorporation in the wide metal line without gap filling pit formation can be achieved. The stress SIV formation was inhibited with excellent EM resistance.

A novel designed microwave plasma torch equipment has been setup for synthesizing the nano diamond powder (NDP). In this equipment microwave plasma can be maintained at rather high pressure with high flow rate of gas. The synthesis process has been performed using mixed gas of CH/sub 4/ and Ar or N/sub 2/ varied with gas flow rate and pressure. The size of synthesized NDP could be controlled from 20 to 50 nm and even bigger to micrometer. The structure and compositions of NDP have been analyzed by high resolution transmission electron microscopy (HRTEM) and transmission electron energy dispersion spectroscopy (TED). The electron diffraction patterns yield good quality of crystalline for big NDP and amorphous structure for smaller NDP. Correlated X-ray diffraction (XRD) and Raman spectroscopy analysis revealed diamond property of NDP.

Proton bombardment technology is integrated into the standard IC process as a post-backend process module to form local semi-insulating regions on mixed-signal/RF chips. With 10/sup 15/ cm/sup -2/, 100 /spl mu/m deep bombardment through mask windows, /spl rho//sub s/=20k/spl sim/50k /spl Omega/.cm regions are formed, which are thermally stable at 200/spl deg/C. High-Q inductors and reliable MOSFETs are made on same chip with no need of tuning the existing wafer process. Design rules are established.

We present the novel concept of "bi-layer metal salicidation" by using Co/Ni stacked films, which showed better film chemical and plasma resistance than pure NiSi. NFET device performance demonstrates 5% Idsat/Ioff (100 nA) improvement and no degradation in terms of sheet resistance, junction leakage and isolation than pure NiSi. We also prove the approach can be implemented easily to manufacturing with conventional post salicide process similar to CoSi/sub 2/ for 45 nm gate technology and below.

For the first time, foundry CMOS logic based RF technology is introduced for 10 Gb/s transceiver in which active and passive RF elements have been realized in a single chip. Superior RF CMOS of 115 GHz f/sub r/, 80 GHz f/sub MAX/, and 2.2 dB NF/sub min/ at 10 GHz has been fabricated by aggressive device scaling and layout optimization. High Q MiM capacitor and spiral Cu inductor have been successfully implemented in the same chip by 0.13 /spl mu/m low-K/Cu BEOL technology. Core 1.0 V MOS and/or junction varactors for VCO at 10 GHz are offerings free of extra cost but realized by elaborated layout. Triple well is introduced to provide superior substrate noise isolation by >10 dB suppression at 10 GHz and beyond.

A new control strategy for a five-level neutral-point-clamped (NPC) H-bridge PWM inverter is proposed. It is shown that a three-level class BD PWM output can be obtained from one leg of the inverter if the phases of both the modulating signal and carrier are appropriately chosen. This new control strategy is called three-level NPC PWM and is very simple. By combining the three-level outputs from both legs of the NPC H-bridge PWM inverter, a five-level PWM output is achieved. A theoretical harmonic analysis of the proposed inverter has been carried out. It is shown that the inverter exhibits superior harmonics suppression property and only multiples of the fourth-order families of the cross-modulated harmonics are present.

This paper presents a simple methodology to convert a hard-switched pulse-width-modulated (PWM) H-bridge converter used in classical digital audio amplifiers into a zero-voltage-switching (ZVS) converter. ZVS is simply achieved by connecting an L-C series branch across the converter output. ZVS occurs during the dead time interval of the PWM signals, giving an effective improvement in the conversion efficiency, output frequency spectrum, and total harmonic distortion (THD). Simplified design procedures are given for choosing the value of the components. A prototype having output power of 20 W and with switching frequency of 705.6 kHz has been built and the experimental results are presented.

Superior RF CMOS of 115 f/sub T/ and 80GHz f/sub MAX/ has been realized by 0.13/spl mu/m low voltage logic based RF CMOS technology by aggressive device scaling and optimized layout. NF/sub min/ of 2.2 dB at 10GHz is achieved even without deep N-well and ground-shielded signal pad. P/sub 1dB/ of near 10dBm can fit Bluetooth requirement and 55% PAE at 2.4GHz address the good potential of sub-100nm CMOS for low voltage RF power applications.

This paper presents an analytical method to calculate the output harmonic characteristics of PWM H-bridge converters with dead time. A three-dimensional (3-D) model derived for generating the pulse-width-modulated (PWM) pulse train is used to consider the effects of dead time. The harmonic characteristics are obtained by applying the double Fourier series to the output PWM waveform. The results obtained by this new technique are verified with simulations using PSpice.

As various robot manipulators and controllers are designed and built, an intelligent device-independent robot manipulator control scheme must be developed for an unmanned manufacturing cell. In this study, a neural-networks based approach has been adopted to control a robot's point-to-point positioning capability. This control scheme lets a robot learn and store the knowledge and adjust itself to maintain its process capability. The approach includes using a modified two-layer counterpropagation network (MTL-CPN) algorithm and efficient training method. Such an architecture can accommodate different robot systems, and is suitable for a variety of tasks and working envelopes.

A CMP-free process by electropolishing (EP) the planar contact plating (CP) Cu film and TaN dry etching which eliminate the stress induced peeling during CMP was demonstrated. Nanometer smoothness and a highly texture of Cu can be achieved by optimizing the EP process. A 4-level Cu/low-k interconnect with CMP-less process was demonstrated with excellent yield. This process improves the throughput on ECP and CMP by two and has less dishing.

This second Topical Report describes the work that was completed between January 1, 1989 and December 31, 1990 in a Cooperative Agreement between Texaco and the US Department of Energy that began on September 30, 1987. During the period that is covered in this report, the development and optimization of in-situ and external desulfurization processes were pursued. The research effort included bench scale testing, PDU scoping tests, process economic studies and advanced instrument testing. Two bench scale studies were performed at the Research Triangle Institute with zinc titanate sorbent to obtain data on its cycle life, sulfur capacity, durability and the effect of chlorides. These studies quantify sulfur capture during simulated air and oxygen-blown gasification for two zinc titanate formulations. Eight PDU runs for a total of 20 days of operation were conducted to evaluate the performance of candidate sorbents for both in-situ and external desulfurization. A total of 47 tests were completed with oxygen and air-blown gasification. Candidate sorbents included iron oxide for in-situ desulfurization and calcium based and mixed metal oxides for external desulfurization. Gasifier performance and sorbent sulfur capture are compared for both air-blown and oxygen-blown operation.

This second Topical Report describes the work that was completed between January 1, 1989 and December 31, 1990 in a Cooperative Agreement between Texaco and the US Department of Energy that began on September 30, 1987. During the period that is covered in this report, the development and optimization of in-situ and external desulfurization processes were pursued. The research effort included bench scale testing, PDU scoping tests, process economic studies and advanced instrument testing. Two bench scale studies were performed at the Research Triangle Institute with zinc titanate sorbent to obtain data on its cycle life, sulfur capacity, durability and the effect of chlorides. These studies quantify sulfur capture during simulated air and oxygen-blown gasification for two zinc titanate formulations. Eight PDU runs for a total of 20 days of operation were conducted to evaluate the performance of candidate sorbents for both in-situ and external desulfurization. A total of 47 tests were completed with oxygen and air-blown gasification. Candidate sorbents included iron oxide for in-situ desulfurization and calcium based and mixed metal oxides for external desulfurization. Gasifier performance and sorbent sulfur capture are compared for both air-blown and oxygen-blown operation.

This research utilized a biomechanical approach for the investigation of body weight effects in a manual-lifting activity. Following a 3-day training session, 10 male subjects performed 6 tasks in 12 trials. For each trial, the subject was directed to use a free style posture to lift a weighted box from the floor to a 0.762m high shelf. In order to evaluate the forces and torques generated by the external load and the body weight acting on the articulations and vertebra during the lifting task, the experimenter used a high-speed camera to record the lifting activity, a GP-8 Sonic Digitizer to translate the motion into coordinates, and a biomechanical program to calculate the forces acting on the L5/S1 disc, the maximum abdominal force,and the torque acting on the abdomen. After the statistical analysis, two regression models were developed, which provide a convenient and useful means to quantify the maximum compressive and shear forces acting on the low back area during a sagittal plane-lifting a...

A general theory of phonon-assisted transition of majority carriers across a grain boundary (GB) is formulated with the GB angle as a variable. It is found that the bulk relaxation time in the crystalline region and the transition time at the GB are the important parameters that determine the transmission coefficient of carriers across the GB. Using the proposed model, an n-type polycrystalline silicon is employed as an example in a numerical calculation.

We study the lattice φ 4 theory in the variational cumulant expansion approach. Its phase structure is given in three, four and five dimensions. The comparison with the results from the other approach is also presented.

The robot process capability problem is outlined and terms are defined. Recent efforts to measure robot capability are reviewed. Two methods were used to analyze robot process capability data: the randomized complete block design method and Taguchi statistical experimental design methods. The purpose of the study was to compare the results obtained by these two methods and determine which method was better for analyzing the data to be used in determining/optimizing a robot's process capability. Three-dimensional (3-D) coordinate data were obtained using a WATSMART vision system to determine a robot's process capability. Three levels of four independent variables—load, X -, Y - and Z - coordinates—were chosen for the study. Both analysis methods yielded similar results in determining a robot's process capability (within 10.4%). The Taguchi methods required significantly fewer data than the randomized complete block design used. Taguchi methods also optimized a robot's process capability.

We study the lattice Φ 4 theory in variational cumulant expansion approach. The phase structure of it is given in 3,4,5 dimensions. The comparision with other results is also presented.

It has been found that the avalanche breakdown voltage of MOSFET is independent of substrate bias and increases linearly with gate voltage in an operation regime. Applying this body-effect independency of breakdown, we obtain a maximum safety drain bias, below which avalanche breakdown is completely avoided. This safety drain voltage can be expressed in an empirical form of gL_{eff}^{\nu} where L eff is the effective channel length and g and ν are coefficients, dependent upon device architecture.

A Type III extended pilot plant evaluation of pelletized and ground Kerr McGee mineral ash residue, which was obtained from the liquefaction of Illinois No. 6 coal at the SRC-I coal liquefaction process pilot plant at Wilsonville, Alabama, was successfully completed at Texaco's Montebello Research Laboratory (MRL). A total of 60 tons of residue was gasified during three runs which were carried out at 950 psig in the MRL High Pressure Solids Gasification Unit II gasifier. The oxygen-to-residue ratio was varied to determine optimum operating conditions. The runs lasted from 6.9 hours to 56.3 hours and a total of 72.9 hours of on-stream time was accumulated. This work was authorized by DOE Delivery Order Number 9 under DOE contract DEAC-01-76ET-10137. It is part of a continuing project to evaluate residual materials from various DOE sponsored coal liquefaction projects to determine their suitability for conversion to hydrogen using one of the Texaco gasification processes. 5 figures, 5 tables.

About 6.7 tons of vacuum tower bottoms (residue) which were obtained during the liquefaction of Illinois No. 6 coal from the H-Coal liquefaction process pilot plant at Catlettsburg, Kentucky were successfully gasified at Texaco's Montebello Research Laboratory. The single 9.5-hour run with H-Coal liquefaction residue-water slurry was completed at 750 to 760 psig gasifier pressure. The run consisted of two test periods, each at a different gasifier temperature. Over 99.6 percent conversion of carbon in the feed to syngas was achieved yielding 32.9 to 33.7 standard cubic feet of dry syngas per pound of residue charged. The oxygen requirement was about 1.0 pound of oxygen per pound of residue. The dry syngas contained 78.5 to 79.7 (vol.) percent carbon monoxide plus hydrogen.

This paper presents the derivation of a generic analytical solution for calculating the harmonic characteristics of multilevel sinusoidal pulse width modulation (SPWM) inverter. This generic solution has advantages over previously published solution since the phase shifts of all the carriers can be made arbitrary. This feature gives a high degree of freedom for evaluating the harmonic structure of a multilevel SPWM inverter with different carrier phase combinations. A multilevel SPWM waveform is decomposed into a series of positive and negative DC biased PWM (DBPWM) waveforms. A 3-dimensional model for describing each individual DBPWM is first derived. After applying the double Fourier series to each waveform, the multilevel SPWM output is then obtained by summing all the DBPWM outputs. The validity of the solution is verified using Pspice simulations.