Depending on the techniques employed, the due date assignment, release, and sequencing procedures in job shop scheduling may depend on one another. This research investigates the effects of these interactions with a simulation model of a dynamic five-machine job shop in which early shipments are prohibited. Performance of the system is measured primarily in terms of the total cost (work-in-process cost, finished goods holding cost, and late penalty) incurred by the shop, but a number of non-cost performance measures are also reported. The results support existence of a three-way interaction between the due date, release, and sequencing procedures as well as interaction between shop utilization and procedure combination. Statistical tests are used to identify those rules that perform best both overall and in combination with other ~1~s .Subject Areas: Scheduling and Simulation.

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Purpose -Managers encounter many decisions that require the simultaneous use of different types of data in their decision-making process. A critical decision area for managers is the performance evaluation of personnel, whether individually or as a member of a team. Performance evaluation is critically essential for the effective management of the human resource of an organization and evaluation of staff that help develop individuals, improve organizational performance, and feed into business planning. Design/methodology/approach -Performance evaluations require and often involve disparate types of information that are vague, incomplete, objective, and subjective. This paper proposes a performance evaluation system of employees considering various performance evaluation criteria using fuzzy logic. The main task in the proposed approach involves determining the performance indices of employees considering their respective performance in various qualitative and quantitative evaluation criteria and then selecting the best employee who holds highest performance index comparing all the indices. Findings -A model is developed for any kind of organization where performance evaluation is significantly important for staff motivation, attitude and behavior development, communicating and aligning individual and organizational aims, and fostering positive relationships between management and staff. Fuzzy control is used to determine the overall performance index by combining results of the performance in selected criteria and provided it in numerical values which will undoubtedly ensure convenience of the concerned human resource personnel during performance rating calculation. Originality/value -This is the first time, a performance evaluation model is developed using fuzzy approach for any kind of organization where performance evaluation is significantly important for staff motivation, attitude and behavior development, communicating and aligning individual and organizational aims, and fostering positive relationships between management and staff.

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Seismic surveys are often constrained by the time needed to activate all the required sources so the source signals do not interfere with each other. Simultaneous source seismic acquisition, also referred to as blended acquisition, is an effective method for reducing the cost and improving the quality of seismic surveys by eliminating the requirement that the sources do not interfere with each other. Independent simultaneous shooting is a unique form of blended acquisition in which sources operate independently of each other and the receiver recording is continuous. This acquisition method is particularly efficient and robust in obtaining high-density source grids for land and marine surveys. Processing the simultaneous source data depends on the randomness of the shot times to create a situation where the signal is coherent, and the interference is random in common-receiver gathers. Although the older and simpler method of separating interfering shots with random noise attenuation works well when the residual interference noise left by the random noise attenuation is acceptable, higher separation quality is possible using a shot separation process based on sparse inversion and compressive sensing methodology. We found that the resulting simultaneous source surveys produced images that were equivalent to or better than conventional seismic surveys, while requiring less acquisition effort, thus reducing costs.

Subsalt imaging has been a long-term challenge for the oil and gas industry. The substantial progress made in data acquisition and imaging since the late 1990s has made some subsalt imaging problems tractable, but building earth models that enable imaging under complex salt remains a challenge. Labor-intensive workflows remain industry standard practice. Not only are these costly and time consuming, they have also performed poorly in many areas of economic interest. Various automatic model-building tools have been proposed to overcome these disadvantages. One such tool, full-waveform inversion (FWI), has already revolutionized velocity-model building in areas with shallow gas. Prior to 2006, imaging in these areas had been considered challenging and labor intensive, just as imaging under complex salt remains today. Modeling indicates that low frequencies and wide offsets may be the key to success when building velocity models using FWI. Just how low and how wide that may be required for FWI success depends on the particular problem. At the Atlantis Field in the deepwater Gulf of Mexico we recently acquired wide-offset ocean-bottom-node data with conventional airguns. By taking care during the acquisition, we recorded usable signal down to a lower frequency than previously achieved. We then applied FWI to the resulting data set and used the resulting velocity model, unmodified, to reverse time migrate the seismic data. It produced some of the best subsalt images of the Atlantis reservoir structure ever seen. Furthermore, the FWI velocity model revealed several major interpretation errors in the legacy salt model; thus the FWI result also offered an excellent basis for updating the salt model with the conventional workflow. These results demonstrate that with appropriate seismic data to support it, and with due care taken during processing and inversion, FWI truly offers a paradigm shift in model building and imaging in areas of complex salt.

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