Critical Path Method (CPM) Scheduling has proven to be an effective project management tool. However, teaching the topic has proven difficult to include all elements of CPM yet keep it simple enough for students to un...Critical Path Method (CPM) Scheduling has proven to be an effective project management tool. However, teaching the topic has proven difficult to include all elements of CPM yet keep it simple enough for students to understand. In an effort to simplify the teaching of critical path method scheduling, the issue of two total floats in an activity does not get the attention necessary to address its occurrence. The objective of this paper is to present a mathematical method to show multiple total floats are possible for an activity. Also presented are suggestions for schedule crashing when multiple total floats are found. Two totals floats can be found if constraints (Lag or Lead) or non-Finish-to-Start (FS) relationships, or both are used in a network diagram. Situations are possible where an activity may have a start total float (STF) of zero but have a finish total float (FTF) greater than zero, or vice versa. Because the critical path generally follows the zero total float, these situations, where either the STF or the FTF is critical while the other is not, determines how the critical path activity must be controlled and crashed. This paper will present approaches of how to crash the schedule when a portion of the activity, either start or finish, is critical. Also presented will be methods to teach the subject matter with or without the use of scheduling software. Critical Path Method was revisited to see what the minimal conditions are needed to have activities with two total float. Generalized crashing methods were studied to see if the methods can be used when two total floats exist.展开更多
目的制备龙胆总苷胃漂浮微丸,并探讨其体外释药特性。方法采用助漂剂十六醇-微晶纤维素(7∶3),以离心造粒法制备空白丸芯(40～60目);采用HPMC-K15M为骨架材料和龙胆总苷等量混合以粉末层积法滚丸(20～30目);采用Eudragit NE 30D进行流...目的制备龙胆总苷胃漂浮微丸,并探讨其体外释药特性。方法采用助漂剂十六醇-微晶纤维素(7∶3),以离心造粒法制备空白丸芯(40～60目);采用HPMC-K15M为骨架材料和龙胆总苷等量混合以粉末层积法滚丸(20～30目);采用Eudragit NE 30D进行流化床包衣,制得龙胆总苷胃漂浮微丸;以龙胆苦苷为指标,《中国药典》2010年版二部附录XC"转篮法"和HPLC法,测定胃漂浮微丸12 h释放度,并用Higuchi等数学模型对释放度数据进行拟合,探讨龙胆总苷胃漂浮微丸释药特性。结果在人工胃液(pH 1.2)中,龙胆总苷胃漂浮微丸具有良好的漂浮性能和良好的缓释效果。累积释放率数据用Ritger-Peppas模型拟合度最高,相关系数R2>0.97,且0.43<n<0.85,说明龙胆总苷胃漂浮微丸释药过程是溶蚀与扩散协同作用。结论龙胆总苷制备胃漂浮微丸工艺可行,且能够达到胃滞留缓释的效果。展开更多
文摘Critical Path Method (CPM) Scheduling has proven to be an effective project management tool. However, teaching the topic has proven difficult to include all elements of CPM yet keep it simple enough for students to understand. In an effort to simplify the teaching of critical path method scheduling, the issue of two total floats in an activity does not get the attention necessary to address its occurrence. The objective of this paper is to present a mathematical method to show multiple total floats are possible for an activity. Also presented are suggestions for schedule crashing when multiple total floats are found. Two totals floats can be found if constraints (Lag or Lead) or non-Finish-to-Start (FS) relationships, or both are used in a network diagram. Situations are possible where an activity may have a start total float (STF) of zero but have a finish total float (FTF) greater than zero, or vice versa. Because the critical path generally follows the zero total float, these situations, where either the STF or the FTF is critical while the other is not, determines how the critical path activity must be controlled and crashed. This paper will present approaches of how to crash the schedule when a portion of the activity, either start or finish, is critical. Also presented will be methods to teach the subject matter with or without the use of scheduling software. Critical Path Method was revisited to see what the minimal conditions are needed to have activities with two total float. Generalized crashing methods were studied to see if the methods can be used when two total floats exist.
文摘目的制备龙胆总苷胃漂浮微丸,并探讨其体外释药特性。方法采用助漂剂十六醇-微晶纤维素(7∶3),以离心造粒法制备空白丸芯(40～60目);采用HPMC-K15M为骨架材料和龙胆总苷等量混合以粉末层积法滚丸(20～30目);采用Eudragit NE 30D进行流化床包衣,制得龙胆总苷胃漂浮微丸;以龙胆苦苷为指标,《中国药典》2010年版二部附录XC"转篮法"和HPLC法,测定胃漂浮微丸12 h释放度,并用Higuchi等数学模型对释放度数据进行拟合,探讨龙胆总苷胃漂浮微丸释药特性。结果在人工胃液(pH 1.2)中,龙胆总苷胃漂浮微丸具有良好的漂浮性能和良好的缓释效果。累积释放率数据用Ritger-Peppas模型拟合度最高,相关系数R2>0.97,且0.43<n<0.85,说明龙胆总苷胃漂浮微丸释药过程是溶蚀与扩散协同作用。结论龙胆总苷制备胃漂浮微丸工艺可行,且能够达到胃滞留缓释的效果。
