{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/101428"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/101428","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"The effect of estimated processing times versus actual (standard) processing times on various performance measures in a pure job shop","abstract":"A comparative simulation study was performed to investigate the effect of uncertainty or unreliability in job processing times on designing schedules in a pure job shop environment. Five performance measures were employed in an effort to examine the effect of variations between estimated and actual processing times. These variations are common in job shop systems where estimations are used to set processing times. It was hypothesized that a variation has an effect on relative system performance. In addition, three priority rules, namely, FIFO, SOT and EDD, were studied to determine the best rule for controlling the shop in situations of unreliable processing times data. The percentage variation in processing times was clearly the dominant variable for most of the performance measures. A 60% variation in estimated processing times appeared to be the maximum level under which the mean flowtime, mean tardiness and percent of late jobs performance measures were insensitive. The simulation results indicated that the makespan and average shop utilization performance measures were insensitive to reliability of input information about processing times for up to a 100%. The performance of FIFO and EDD priority rules suffered drastically while SOT was the least sensitive to the reliability of processing times information.","abstract_html":"A comparative simulation study was performed to investigate the effect of uncertainty or unreliability in job processing times on designing schedules in a pure job shop environment. Five performance measures were employed in an effort to examine the effect of variations between estimated and actual processing times. These variations are common in job shop systems where estimations are used to set processing times. It was hypothesized that a variation has an effect on relative system performance. In addition, three priority rules, namely, FIFO, SOT and EDD, were studied to determine the best rule for controlling the shop in situations of unreliable processing times data. The percentage variation in processing times was clearly the dominant variable for most of the performance measures. A 60% variation in estimated processing times appeared to be the maximum level under which the mean flowtime, mean tardiness and percent of late jobs performance measures were insensitive. The simulation results indicated that the makespan and average shop utilization performance measures were insensitive to reliability of input information about processing times for up to a 100%. The performance of FIFO and EDD priority rules suffered drastically while SOT was the least sensitive to the reliability of processing times information.","abstract_has_math":false,"creators":["Emaminezhad, Farzad"],"institution":"Virginia Polytechnic Institute and State University","degree_name":"M.S.","degree_level":"masters","degree_discipline":"Industrial Engineering and Operations Research","degree_department":"Industrial Engineering and Operations Research","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1983,"date_issued":"1983","date_published":"1983","updated_at":"2026-07-22T22:19:41Z","subjects":[],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10919/101428","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Industrial Engineering and Operations Research"]},{"key":"dc:creator","label":"Author","values":["Emaminezhad, Farzad"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2020-12-15T19:11:33Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2020-12-15T19:11:33Z"]},{"key":"dc:date.issued","label":"Date","values":["1983"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Polytechnic Institute and State University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Industrial Engineering and Operations Research"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/101428"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["A comparative simulation study was performed to investigate the effect of uncertainty or unreliability in job processing times on designing schedules in a pure job shop environment. Five performance measures were employed in an effort to examine the effect of variations between estimated and actual processing times. These variations are common in job shop systems where estimations are used to set processing times. It was hypothesized that a variation has an effect on relative system performance. In addition, three priority rules, namely, FIFO, SOT and EDD, were studied to determine the best rule for controlling the shop in situations of unreliable processing times data. The percentage variation in processing times was clearly the dominant variable for most of the performance measures. A 60% variation in estimated processing times appeared to be the maximum level under which the mean flowtime, mean tardiness and percent of late jobs performance measures were insensitive. The simulation results indicated that the makespan and average shop utilization performance measures were insensitive to reliability of input information about processing times for up to a 100%. The performance of FIFO and EDD priority rules suffered drastically while SOT was the least sensitive to the reliability of processing times information."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["M.S."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The effect of estimated processing times versus actual (standard) processing times on various performance measures in a pure job shop"]}]}],"canonical_facts":{"dc:contributor.department":["Industrial Engineering and Operations Research"],"dc:creator":["Emaminezhad, Farzad"],"dc:date.accessioned":["2020-12-15T19:11:33Z"],"dc:date.available":["2020-12-15T19:11:33Z"],"dc:date.issued":["1983"],"dc:description.abstract":["A comparative simulation study was performed to investigate the effect of uncertainty or unreliability in job processing times on designing schedules in a pure job shop environment. Five performance measures were employed in an effort to examine the effect of variations between estimated and actual processing times. These variations are common in job shop systems where estimations are used to set processing times. It was hypothesized that a variation has an effect on relative system performance. In addition, three priority rules, namely, FIFO, SOT and EDD, were studied to determine the best rule for controlling the shop in situations of unreliable processing times data. The percentage variation in processing times was clearly the dominant variable for most of the performance measures. A 60% variation in estimated processing times appeared to be the maximum level under which the mean flowtime, mean tardiness and percent of late jobs performance measures were insensitive. The simulation results indicated that the makespan and average shop utilization performance measures were insensitive to reliability of input information about processing times for up to a 100%. 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