The performance of a call center is sensitive to customer abandonment. In this survey paper, we focus on G/GI/n ＋ GI parallel-server queues that serve as a building block to model call center operations. Such a queue...The performance of a call center is sensitive to customer abandonment. In this survey paper, we focus on G/GI/n ＋ GI parallel-server queues that serve as a building block to model call center operations. Such a queue has a general arrival process （the G ）, independent and identically distributed （iid） service times with a general distribution （the first G1 ）, and iid patience times with a general distribution （the ＋GI）. Following the square-root safety staffing rule, this queue can be operated in the quality- and efficiency-driven （QED） regime, which is characterized by large customer volume, the waiting times being a fraction of the service times, only a small fraction of customers abandoning the system, and high server utilization. Operational efficiency is the central target in a system whose staffing costs dominate other expenses. If a moderate fraction of customer abandonment is allowed, such a system should be operated in an overloaded regime known as the efficiency-driven （ED） regime. We survey recent results on the many-server queues that are operated in the QED and ED regimes. These results include the performance insensitivity to patience time distributions and diffusion and fluid approximate models as practical tools for performance analysis.展开更多
China's economic growth has been declining continuously at a rapid rate since 2011. It dropped to 6.7% in 2016 by more than 3% from nearly 10% average growth rate during 1979-2010. As for its causes, there are dif...China's economic growth has been declining continuously at a rapid rate since 2011. It dropped to 6.7% in 2016 by more than 3% from nearly 10% average growth rate during 1979-2010. As for its causes, there are different interpretations among Chinese economists. One of the interpretations, which is held by some scholars including Justin Yifu Lin, is that external and cyclical factors are the main causes for the decline. The author disagrees with this viewpoint and holds that the root cause of economic deceleration is the delay in deep institutional reforms. An inclusive economy and state coercive capacity are two essential ingredients for sustaining economic prosperity. China must further enhance economic inclusiveness, and accelerate its transition into an efficienc y? driven and innovatio driven economy through deepened comprehensive marketization reforms. Meanwhile, it should further strengthen the rule of law to build a limited government that is capable, accountable, effective and caring.展开更多
基金supported in part by NSF grants CMMI-0825840 and CMMI-1030589
文摘The performance of a call center is sensitive to customer abandonment. In this survey paper, we focus on G/GI/n ＋ GI parallel-server queues that serve as a building block to model call center operations. Such a queue has a general arrival process （the G ）, independent and identically distributed （iid） service times with a general distribution （the first G1 ）, and iid patience times with a general distribution （the ＋GI）. Following the square-root safety staffing rule, this queue can be operated in the quality- and efficiency-driven （QED） regime, which is characterized by large customer volume, the waiting times being a fraction of the service times, only a small fraction of customers abandoning the system, and high server utilization. Operational efficiency is the central target in a system whose staffing costs dominate other expenses. If a moderate fraction of customer abandonment is allowed, such a system should be operated in an overloaded regime known as the efficiency-driven （ED） regime. We survey recent results on the many-server queues that are operated in the QED and ED regimes. These results include the performance insensitivity to patience time distributions and diffusion and fluid approximate models as practical tools for performance analysis.
文摘China's economic growth has been declining continuously at a rapid rate since 2011. It dropped to 6.7% in 2016 by more than 3% from nearly 10% average growth rate during 1979-2010. As for its causes, there are different interpretations among Chinese economists. One of the interpretations, which is held by some scholars including Justin Yifu Lin, is that external and cyclical factors are the main causes for the decline. The author disagrees with this viewpoint and holds that the root cause of economic deceleration is the delay in deep institutional reforms. An inclusive economy and state coercive capacity are two essential ingredients for sustaining economic prosperity. China must further enhance economic inclusiveness, and accelerate its transition into an efficienc y? driven and innovatio driven economy through deepened comprehensive marketization reforms. Meanwhile, it should further strengthen the rule of law to build a limited government that is capable, accountable, effective and caring.
