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[1] We develop a ray-tracing package for the calculation of path delays of microwave signals in the troposphere based on numerical weather models which we use for the determination of the delays of geodetic Very Long Baseline Interferometry (VLBI) observations. We show results for a two-week campaign of continuous VLBI sessions in 2008 (CONT08), where we apply those ray-traced delays and analyze the repeatability of baseline lengths in comparison to a standard approach with zenith delays and mapping functions. We find improvement in baseline length repeatabilities when no tropospheric gradients are estimated in the analysis. Furthermore, ray-traced delays are applied for Intensive sessions containing the stations Tsukuba (Japan) and Wettzell (Germany) for the determination of Universal Time (UT1). We perform an external validation using GPS-derived length-of-day values and find an improvement for UT1 with ray-traced delays by up to 4.5%.Citation: Nafisi, V., M. Madzak, J. Böhm, A. A. Ardalan, and H. Schuh (2012), Ray-traced tropospheric delays in VLBI analysis, Radio Sci., 47, RS2020,

A recent article reported the results of a study on the effects of two kanban policy variables-the length of withdrawal cycle and the type of priority rule-on average customer wait time and total inventory. This study extends that work by adding two kanban policy variables and two performance criteria. It reports the results of simulation experiments that were conducted to determine how four policy variableswithdrawal cycle, priority rule, status of waiting withdrawal kanbans, and number of kanbans influence four performance criteria-average customer wait-time, total inventory, and average number of full containers in the input and output stock points of stations. It was found that the information about waiting withdrawal kanbans in sequencing decisions results in the simultaneous improvement in two conflicting objectives-ustomer wait time and total inventory. Also, the effects of including the information regarding the status of waiting withdrawal kanbans on system performance are larger than the effects associated with the type of priority rule. The results provide insights into determining the level of each policy variable while fully considering the possible interactions among the variables and the levels of other policy variables to improve system performance. These insights allow for setting the levels of policy variables to make the improvement process smooth. Subject Areas: Flow Shops, Just-In-Time Systems, Kanban Policy, and Simulation. Analysis of Local Decision Ruleswait time, in a dual-kanban flow shop with one kanban. The main question motivating Berkley & Kiran's research was "given the promising results of [previous studies] and the long history of research with respect to SPT. why are station supervisors using FCFS?" (p. 565). Their interesting study addresses the question well and demonstrates how first-come, first-served (FCFS) results in higher performance. However, it provides no additional insights for improving the performance of the system. The purpose of this paper is to extend Berkley and Kiran's (1991) study by introducing a new policy variable-status of waiting withdrawal kanbans, and providing managerial insights for improving system performance. This study includes two more policy variables-status of waiting withdrawal kanbans and number of kanbans, and two more performance criteria-input and output stock point inventory. This paper analyzes the relationships between independent variables, such as the number of kanbans, withdrawal cycle, priority rule, and status of waiting withdrawal kanbans, and dependent variables, such as customer wait time, total inventory, input inventory, and output inventory levels. A detailed analysis of these relationships provides important insights into improving the performance of the system. These extensions are important for the following reasons.