scholarly journals Design Tradeoffs for Improved Performance in MQCA-Based Systems

2008 ◽  
Author(s):  
Michael Niemier ◽  
Aaron Dingler ◽  
X. Sharon Hu
Keyword(s):  
Improved Performance ◽  
Design Tradeoffs

Design of Parallel Kinematic XY Flexure Mechanisms

2005 ◽  
Author(s):  
Shorya Awtar ◽  
Alexander H. Slocum
Keyword(s):  
Performance Measures ◽  
Significant Error ◽  
Nonlinear Analyses ◽  
Element Analysis ◽  
Flexure Mechanism ◽  
Nonlinear Force ◽  
Parallel Kinematic ◽  
Improved Performance ◽  
Design Tradeoffs ◽  
Force Displacement

This paper presents parallel kinematic XY mechanism designs that are based on a systematic constraint pattern. The constraint pattern, realized by means of double parallelogram flexure modules, is such that it allows large ranges of motion without over-constraining the mechanism or generating significant error motions. Nonlinear force-displacement characteristics of the double parallelogram flexure are used in analytically predicting the performance measures of the proposed XY mechanisms. Comparisons between closed-form linear and nonlinear analyses are presented to highlight the inadequacy of the former. Fundamental design tradeoffs in flexure mechanism performance are discussed qualitatively and quantitatively. It is shown that geometric symmetry in the constraint arrangement relaxes some of the design tradeoffs, resulting in improved performance. The nonlinear analytical predictions are validated by means of Finite Element Analysis and experimental measurements.

Constraint-Based Design of Parallel Kinematic XY Flexure Mechanisms

2006 ◽  
Vol 129 (8) ◽  
pp. 816-830 ◽  
Author(s):  
Shorya Awtar ◽  
Alexander H. Slocum
Keyword(s):  
Performance Characteristics ◽  
Element Analysis ◽  
Nonlinear Load ◽  
Flexure Mechanism ◽  
Nonlinear Force ◽  
Parallel Kinematic ◽  
Improved Performance ◽  
Design Tradeoffs ◽  
Cross Axis ◽  
Force Displacement

This paper presents parallel kinematic XY flexure mechanism designs based on systematic constraint patterns that allow large ranges of motion without causing over-constraint or significant error motions. Key performance characteristics of XY mechanisms such as mobility, cross-axis coupling, parasitic errors, actuator isolation, drive stiffness, lost motion, and geometric sensitivity, are discussed. The standard double parallelogram flexure module is used as a constraint building-block and its nonlinear force-displacement characteristics are employed in analytically predicting the performance characteristics of two proposed XY flexure mechanism designs. Fundamental performance tradeoffs, including those resulting from the nonlinear load-stiffening and elastokinematic effects, in flexure mechanisms are highlighted. Comparisons between closed-form linear and nonlinear analyses are presented to emphasize the inadequacy of the former. It is shown that geometric symmetry in the constraint arrangement relaxes some of the design tradeoffs, resulting in improved performance. The nonlinear analytical predictions are validated by means of computational finite element analysis and experimental measurements.

Toward The Simultaneous Correction of Spherical and Chromatic Aberration in Electron Optics by Means of an Electrostatic Electron Mirror

1990 ◽  
Vol 48 (1) ◽  
pp. 206-207
Author(s):  
Gertrude. F. Rempfer
Keyword(s):  
Chromatic Aberration ◽  
Transverse Magnetic ◽  
Objective Lens ◽  
Ion Imaging ◽  
Corrected Image ◽  
Electric And Magnetic Fields ◽  
Chromatic Aberrations ◽  
Improved Performance ◽  
Electron Microscopes ◽  
Image Planes

Optimum performance in electron and ion imaging instruments, such as electron microscopes and probe-forming instruments, in most cases depends on a compromise either between imaging errors due to spherical and chromatic aberrations and the diffraction error or between the imaging errors and the current in the image. These compromises result in the use of very small angular apertures. Reducing the spherical and chromatic aberration coefficients would permit the use of larger apertures with resulting improved performance, granted that other problems such as incorrect operation of the instrument or spurious disturbances do not interfere. One approach to correcting aberrations which has been investigated extensively is through the use of multipole electric and magnetic fields. Another approach involves the use of foil windows. However, a practical system for correcting spherical and chromatic aberration is not yet available.Our approach to correction of spherical and chromatic aberration makes use of an electrostatic electron mirror. Early studies of the properties of electron mirrors were done by Recknagel. More recently my colleagues and I have studied the properties of the hyperbolic electron mirror as a function of the ratio of accelerating voltage to mirror voltage. The spherical and chromatic aberration coefficients of the mirror are of opposite sign (overcorrected) from those of electron lenses (undercorrected). This important property invites one to find a way to incorporate a correcting mirror in an electron microscope. Unfortunately, the parts of the beam heading toward and away from the mirror must be separated. A transverse magnetic field can separate the beams, but in general the deflection aberrations degrade the image. The key to avoiding the detrimental effects of deflection aberrations is to have deflections take place at image planes. Our separating system is shown in Fig. 1. Deflections take place at the separating magnet and also at two additional magnetic deflectors. The uncorrected magnified image formed by the objective lens is focused in the first deflector, and relay lenses transfer the image to the separating magnet. The interface lens and the hyperbolic mirror acting in zoom fashion return the corrected image to the separating magnet, and the second set of relay lenses transfers the image to the final deflector, where the beam is deflected onto the projection axis.

Bleaching optimization at WestRock mill in Covington, Virginia

TAPPI Journal ◽  
2016 ◽  
Vol 15 (9) ◽  
pp. 581-586 ◽  
Author(s):  
RICARDO B. SANTOS ◽  
PETER W. HART ◽  
DOUGLAS C. PRYKE ◽  
JOHN VANDERHEIDE
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Hydroxide ◽  
Chlorine Dioxide ◽  
Capital Expenditures ◽  
Equipment Repair ◽  
Optimization Program ◽  
Hardwood Pulp ◽  
Improved Performance

The WestRock mill in Covington, VA, USA, initiated a long term diagnostic and optimization program for all three of its bleaching lines. Benchmarking studies were used to help identify optimization opportunities. Capital expenditures for mixing improvement, filtrate changes, equipment repair, other equipment changes, and species changes were outside the scope of this work. This focus of this paper is the B line, producing southern hardwood pulp in a D(EP)DD sequence at 88% GE brightness. The benchmarking study and optimization work identified the following opportunities for improved performance: nonoptimal addition of caustic and hydrogen peroxide to the (EP) stage, carryover of D0 filtrate to the (EP) stage, and carryover of (EP) filtrate to the D1 stage. As a result of actions the mill undertook to address these opportunities, D0 kappa factor decreased about 5%, sodium hydroxide consumption in the (EP) stage decreased about 35%, chlorine dioxide consumption in the D1 stage decreased about 25%, and overall bleaching cost decreased about 15%.

Single-Phase AC-AC Current Source Converter with Improved Performance

2015 ◽  
Vol 135 (12) ◽  
pp. 1237-1238
Author(s):  
Yasuhiko Neba ◽  
Hirokazu Matsumoto ◽  
Yuta Kawasaki
Keyword(s):  
Single Phase ◽  
Current Source ◽  
Current Source Converter ◽  
Ac Current ◽  
Improved Performance

Improved Performance with New Casing while Drilling Bit Design Elements - Development and Case Studies

2011 ◽  
Author(s):  
Chay Yoeng Chung ◽  
Ahmad Hakam Abdul Razak ◽  
Ming Zo Tan ◽  
Sharp Ugwuocha ◽  
Eric Twardowski ◽  
...  
Keyword(s):  
Case Studies ◽  
Design Elements ◽  
Improved Performance ◽  
Drilling Bit

Ru Passivated and Ru Doped e-TaN surfaces as Combined Barrier and Liner Material for Copper Interconnects: A First Principles Study

2018 ◽  
Author(s):  
Suresh Natarajan ◽  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
First Principles ◽  
Film Growth ◽  
Early Stage ◽  
Copper Interconnects ◽  
Liner Material ◽  
Critical Dimensions ◽  
Industry Standard ◽  
Cu Film ◽  
Improved Performance ◽  
And Diffusion

<div>As the critical dimensions of transistors continue to be scaled down to facilitate improved performance and device speeds, new ultrathin materials that combine diffusion barrier and seed/liner properties are needed for copper interconnects at these length scales. Ideally, to facilitate coating of high aspect ratio structures, this alternative barrier+liner material should only consist of one or as few layers as possible. We studied TaN, the current industry standard for Cu diffusion barriers, and Ru, which is a</div><div>suitable liner material for Cu electroplating, to explore how combining these two materials in a barrier+liner material influences the adsorption of Cu atoms in the early stage of Cu film growth. To this end, we carried out first-principles simulations of the adsorption and diffusion of Cu adatoms at Ru-passivated and Ru-doped e-TaN(1 1 0) surfaces. For comparison, we also studied the behaviour of Cu and Ru adatoms at the low index surfaces of e-TaN, as well as the interaction of Cu adatoms with the (0 0 1) surface of hexagonal Ru. Our results confirm the barrier and liner properties of TaN and Ru, respectively while also highlighting the weaknesses of both materials. Ru passivated TaN was found to have improved binding with Cu adatoms as compared to the bare TaN and Ru surfaces.</div><div>On the other hand, the energetic barrier for Cu diffusion at Ru passivated TaN surface was lower than at the bare TaN surface which can promote Cu agglomeration. For Ru-doped TaN however, a decrease in Cu binding energy was found in addition to favourable migration of the Cu adatoms toward the doped Ru atom and unfavourable migration away from it or into the bulk. This suggests that Ru doping sites in the TaN surface can act as nucleation points for Cu growth with high migration barrier preventing agglomeration and allow electroplating of Cu. Therefore Ru-doped TaN is proposed as a candidate for a combined barrier+liner material with reduced thickness.</div>

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