Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 8 of 8

Full-Text Articles in Systems Engineering

The Effect Of A Knee Support On The Biomechanical Response Of The Low Back, Yu Shu, Zongliang Jiang, Xu Xu, Gary A. Mirka Nov 2007

The Effect Of A Knee Support On The Biomechanical Response Of The Low Back, Yu Shu, Zongliang Jiang, Xu Xu, Gary A. Mirka

Gary A. Mirka

Stooping and squatting postures are seen in a number of industries (e.g., agriculture, construction) where workers must work near ground level for extended periods of time. The focus of the current research was to evaluate a knee support device designed to reduce the biomechanical loading of these postures. Ten participants performed a series of sudden loading tasks while in a semisquat posture under two conditions of knee support (no support and fully supported) and two conditions of torso flexion (45 and 60°). A weight was released into the hands of the participants who then came to steady state while maintaining …


Evaluation Of Surface Residual Stresses In Friction Stir Welds Due To Laser And Shot Peening, Omar Hatamleh, Iris V. Rivero, Jeds Lyons Oct 2007

Evaluation Of Surface Residual Stresses In Friction Stir Welds Due To Laser And Shot Peening, Omar Hatamleh, Iris V. Rivero, Jeds Lyons

Iris V. Rivero

The effects of laser, and shot peening on the residual stresses in friction stir welds (FSW) has been investigated. The surface residual stresses were measured at five different locations across the weld in order to produce an adequate residual stress profile. The residual stresses before and after sectioning the coupon from the welded plate were also measured, and the effect of coupon size on the residual stress relaxation was determined and characterized. Measurements indicate that residual stresses were not uniform along the welded plate, and large variation in stress magnitude could be exhibited at various locations along the FSW plate. …


Ranking Maintenance Strategies From The Point Of View Of Lean Thinking: Group Decision Making Model By Using Borda Method, Mehdi Jafarian, Kamran Shahanaghi, Aliakbar Faegh, Majid Samsami Jan 2007

Ranking Maintenance Strategies From The Point Of View Of Lean Thinking: Group Decision Making Model By Using Borda Method, Mehdi Jafarian, Kamran Shahanaghi, Aliakbar Faegh, Majid Samsami

Mehdi Jafarian

The selection of maintenance strategies is a typical multiple criteria decision-making (MCDM) problem. There have been taken different maintenance strategies in order to obtaining optimistic maintenance strategy. In this paper we aim to rank different maintenance strategies from the point of view of lean thinking. After obtaining information from experts whose expertness is in field of maintenance, in order to ranking these strategies we form a group decision making model and solve this model by using Borda method. Finally we analyze its results


An Introduction To Maintenance, Kamran Shahanaghi, Mehdi Jafarian Jan 2007

An Introduction To Maintenance, Kamran Shahanaghi, Mehdi Jafarian

Mehdi Jafarian

در فضای رقابتی امروز، بنگاه‏های اقتصادی در تلاشی مستمر برای دستیابی به کیفیت بالا، هزینه پایین، افزایش سرعت در ارائه کالا و خدمات و ... می‏باشند. بنابراین دستیابی به اهداف فوق را می‏توان در زمره مهمترین دغدغه‏های مدیران امروزی قلمداد نمود. نگهداری و تعمیرات نیز به عنوان یکی از مهمترین فرآیندهای یک بنگاه اقتصادی از این قاعده مستثنا نبوده و در زیر ذره بین مدیران و کارشناسان قرار گرفته است. در این مقاله سعی نویسندگان بر این بوده است تا برخی از مهمترین جنبه‏های پژوهشی مطرح در این حوزه را عنوان نمایند.


Optimization Models For The Single Machine Scheduling Problem With A Single Flexible Maintenance Activity And Stochastic Maintenance Activities Time, Kamran Shahanaghi, Azizolah Jafari, Mehdi Jafarian, Hamid Babaei, Hojat Mehrazmay, Majid Beikverdi, Ahmad Yazdian Jan 2007

Optimization Models For The Single Machine Scheduling Problem With A Single Flexible Maintenance Activity And Stochastic Maintenance Activities Time, Kamran Shahanaghi, Azizolah Jafari, Mehdi Jafarian, Hamid Babaei, Hojat Mehrazmay, Majid Beikverdi, Ahmad Yazdian

Mehdi Jafarian

In this paper, modeling and solving of a single machine scheduling problem with a single flexible maintenance activity and stochastic maintenance activities time was considered. Also it assumes that the all activities are resumable. Chen solved and investigate complexity of this problem without probabilistic condition by Mixed binary integer programming (BIP) so we solving this problem with considering stochastic programming concepts. An example has investigated at the end chapter to show actual consequences by Lingo.


The Optimization Of The Threshold For The Preventive Maintenance Actions In A Condition-Based Maintenance Program Via Dynamic Programming Approach, Mehdi Jafarian, Majid Beikverdi, Kamran Shahanaghi, Zeinab Nezhadbiglari Jan 2007

The Optimization Of The Threshold For The Preventive Maintenance Actions In A Condition-Based Maintenance Program Via Dynamic Programming Approach, Mehdi Jafarian, Majid Beikverdi, Kamran Shahanaghi, Zeinab Nezhadbiglari

Mehdi Jafarian

The last step of a condition based maintenance (CBM) program is maintenance decision-making. This step is the most important and the most critical stage of maintenance for executive personnel and management whom work on taking maintenance actions. This decision making would be done according to certain criteria such as risk, cost, reliability and availability. This paper considered a dynamic programming model to optimization of the threshold for the preventive maintenance actions in a condition-based maintenance program. The basis of this modeling is the average cost of maintenance actions, failures and exchanges. In this paper, we improved the memory of the …


Cbm With Economic Decision Making: A New Modelling By Markov Chain, Kamran Shahanaghi, Mehdi Jafarian Jan 2007

Cbm With Economic Decision Making: A New Modelling By Markov Chain, Kamran Shahanaghi, Mehdi Jafarian

Mehdi Jafarian

فعالیت های نگهداری و تعمیرات در هر بنگاه اقتصادی از یک سو سبب کاهش هزینه های ناشی از عدم فعالیت دستگاه ها، هزینه های تعمیرات و سود از دست رفته، شده و از سوی دیگر به عنوان فعالیتی هزینه بر، هزینه های گاها سنگینی را به سازمان وارد می¬سازد. از این رو توسعه سیاست های نگهداری و تعمیرات و بهینه سازی هر یک از این سیاست ها، عاملی مهم در کاهش هزینه های سازمان خواهد بود. در این میان فرآیند نگهداری و تعمیرات مبتنی بر شرایط، به عنوان یکی از کاراترین سیاست¬های نگهداری و تعمیرات، با حذف فعالیت های نگهداری …


An Evaluation Of Real-Time Cognitive State Classification In A Harsh Operational Environment, Michael C. Dorneich, Santosh Mathan, Patricia May Ververs, Stephen D. Whitlow Jan 2007

An Evaluation Of Real-Time Cognitive State Classification In A Harsh Operational Environment, Michael C. Dorneich, Santosh Mathan, Patricia May Ververs, Stephen D. Whitlow

Michael C. Dorneich

This paper describes an evaluation conducted with a full platoon of 32 Soldiers at Aberdeen Proving Grounds' MOUT site in Aberdeen, MD. The objective was to assess the cognitive workload classification techniques driven by neuro-physiological (EEG) and physiological (ECG) sensors. In a first ever evaluation of real-time cognitive monitoring in the harsh operational environment, the assessment culminated in a three phase, 24-hour mission consisting of a coordinated Route Reconnaissance, a Cordon and Search of a village, and a Hasty Defense operation. Task load levels were manipulated by introducing unexpected and unplanned events requiring re-planning and extensive coordination by the leadership …