The placement optimization program: a practical solution to the disk file assignment problem

1989 ◽  
Vol 17 (1) ◽  
pp. 1-10 ◽  
Author(s):  
J. Wolf
Keyword(s):  
Assignment Problem ◽  
Disk File ◽  
Practical Solution ◽  
Optimization Program ◽  
Placement Optimization

Simultaneous Optimization Formulation of a Discrete–Continuous Transportation System

2003 ◽  
Vol 1857 (1) ◽  
pp. 11-20 ◽  
Author(s):  
S. C. Wong ◽  
Y. C. Du ◽  
H. W. Ho ◽  
L. J. Sun
Keyword(s):  
Assignment Problem ◽  
Travel Demand ◽  
Traffic Assignment ◽  
Travel Cost ◽  
Transportation System ◽  
Simultaneous Optimization ◽  
Sensitivity Analyses ◽  
Optimization Program ◽  
Traffic Assignment Problem ◽  
The Continuum

Consider a city with a highly compact central business district (CBD) in which commuters’ origins are continuously dispersed. The travel demand is dependent on the total travel cost to the CBD. The transportation system is divided into two layers: major freeways and dense surface streets. Whereas the major freeway network is modeled according to the conventional discrete network approach, the dense surface streets are approximated as a continuum. Travelers to the CBD either travel on the continuum (surface streets) and then exchange to the discrete network (freeways) at an interchange (ramp) before moving to the CBD on the discrete network, or they travel directly to the CBD on the continuum. Specific travel cost–flow relationships for the two layers of transportation facilities are considered. A traffic equilibrium model is developed for this discrete–continuous transportation system in which for a particular origin no traveler can reduce his or her individual travel cost to the CBD by unilaterally changing routes. The problem is formulated as a simultaneous optimization program with two subproblems. One subproblem is a traffic assignment problem from the interchanges to the CBD in the discrete network, and the other is a traffic assignment problem with multiple centers (i.e., the interchange points and the CBD) in the continuous system. A Newtonian algorithm based on the sensitivity analyses of the two subproblems is proposed to solve the resultant simultaneous optimization program. A numerical example is given to demonstrate the effectiveness of the proposed methodology.

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%.

Access to Highly Functionalized Cyclopentenones via Diastereoselective Pauson Khand Reaction of Siloxy-Tethered 1,7-Enynes

2019 ◽  
Author(s):  
Austin Gallagher ◽  
Huan Tian ◽  
Osmar A. Torres-Herrera ◽  
Shuai Yin ◽  
Anxin Xie ◽  
...  
Keyword(s):  
Functional Group ◽  
Practical Solution

A diastereoselective Co<sub>2</sub>(CO)<sub>8</sub>-mediated Pauson-Khand reaction (PKR) of siloxy-tethered 1,7-enynes for the synthesis of cyclopentaoxasilinones has been developed. This transformation can be performed on a multi-gram scale and is characterized by broad substrate scope, functional group compatibility, and high chemo- and diastereoselectivity. Oxidation of the resulting cyclopentaoxasilinones delivers stereoenriched β-alkylated cyclopentenones, which are inaccessible by intermolecular PKRs. This research provides a practical solution to the challenges associated with the classical intermolecular PKR.

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