Special investigation of the City of Mingo for the period September 1, 2002 through June 30, 2006

Special investigation of the City of Mingo for the period September 1, 2002 through June 30, 2006

On the throughput-WIP trade-off in queueing systems, diminishing returns and the threshold property: A linear programming approach

We present a new unifying framework for investigating throughput-WIP(Work-in-Process) optimal control problems in queueing systems,based on reformulating them as linear programming (LP) problems withspecial structure: We show that if a throughput-WIP performance pairin a stochastic system satisfies the Threshold Property we introducein this paper, then we can reformulate the problem of optimizing alinear objective of throughput-WIP performance as a (semi-infinite)LP problem over a polygon with special structure (a thresholdpolygon). The strong structural properties of such polygones explainthe optimality of threshold policies for optimizing linearperformance objectives: their vertices correspond to the performancepairs of threshold policies. We analyze in this framework theversatile input-output queueing intensity control model introduced byChen and Yao (1990), obtaining a variety of new results, including (a)an exact reformulation of the control problem as an LP problem over athreshold polygon; (b) an analytical characterization of the Min WIPfunction (giving the minimum WIP level required to attain a targetthroughput level); (c) an LP Value Decomposition Theorem that relatesthe objective value under an arbitrary policy with that of a giventhreshold policy (thus revealing the LP interpretation of Chen andYao's optimality conditions); (d) diminishing returns and invarianceproperties of throughput-WIP performance, which underlie thresholdoptimality; (e) a unified treatment of the time-discounted andtime-average cases.

Special investigation of the City of Center Point Library for the period January 1, 2006 through December 6, 2007

Special investigation of the City of Center Point Library for the period January 1, 2006 through December 6, 2007

Special investigation of the City of Schleswig for the period January 1, 2003 through January 31, 2007

Special investigation of the City of Schleswig for the period January 1, 2003 through January 31, 2007

Special report on the City of Norwalk for the period July 1, 2006 through April 9, 2008

Special report on the City of Norwalk for the period July 1, 2006 through April 9, 2008

Special report on the Woodbury County Sheriff’s Office for the period December 1, 2004 through December 31, 2007

Special report on the Woodbury County Sheriff’s Office for the period December 1, 2004 through December 31, 2007

Special investigation of the City of Searsboro for the period July 1, 2000 through October 9, 2006

Special investigation of the City of Searsboro for the period July 1, 2000 through October 9, 2006

Special investigation of the City of Vinton Parks and Recreation Department for the period July 19, 2001 through August 30, 2007

Special investigation of the City of Vinton Parks and Recreation Department for the period July 19, 2001 through August 30, 2007

Special investigation of selected transactions at Perry High School for the period July 1, 2005 through November 30, 2007

Special investigation of selected transactions at Perry High School for the period July 1, 2005 through November 30, 2007

Report on a special investigation of the West Marshall Community School District for the period January 1, 2001 through June 30, 2007

Report on a special investigation of the West Marshall Community School District for the period January 1, 2001 through June 30, 2007

Report on a special investigation of the City of Durant for the period July 1, 2000 through May 6, 2008

Report on a special investigation of the City of Durant for the period July 1, 2000 through May 6, 2008

Report on a special investigation of the City of Macedonia for the period June 26, 2006 through September 30, 2008

Report on a special investigation of the City of Macedonia for the period June 26, 2006 through September 30, 2008

Report on a special investigation of the City of Halbur for the period July 1, 1995 through June 30, 2008

Report on a special investigation of the City of Halbur for the period July 1, 1995 through June 30, 2008