A branch and bound method in a permutation flow shop with blocking and setup times

In this paper it is presented an improvement of the branch and bound algorithm for the permutation flow shop problem with blocking-in-process and setup times with the objective of minimizing the total flow time and tardiness, which is known to be NP-Hard when there are two or more machines involved. With that objective in mind, a new machine-based lower bound that exploits some structural properties of the problem. A database with 27 classes of problems, varying in number of jobs (n) and number of machines (m) was used to perform the computational experiments. Results show that the algorithm can deal with most of the problems with less than 20 jobs in less than one hour. Thus, the method proposed in this work can solve the scheduling of many applications in manufacturing environments with limited buffers and separated setup times.

Nigeria

The Nigerian economy is at a critical juncture. A weak pre-crisis economy characterized by falling per capita income, double-digit inflation, significant governance vulnerabilities and limited buffers, is grappling with multiple shocks from the COVID-19 pandemic. Real output is projected to contract by 3.2 percent in 2020, with a weak recovery likely to keep per capita income stagnant and no higher than the 2010 level in the medium term. Policy adjustment and reforms are urgently needed to navigate this crisis and change the long-running lackluster course.

Mongolia

During the three-year EFF which expired at end-May, Mongolia experienced rapid economic growth and was able to make some progress in the reduction of key vulnerabilities. However, with the outbreak of the global pandemic, the outlook has now deteriorated sharply. There are few domestic cases of the virus, but real GDP is expected to contract by 1 percent in 2020 due to a collapse in external demand and the domestic impact of social distancing measures. With still high public debt, net international reserves near zero, and a difficult near-term amortization schedule, Mongolia has limited buffers to withstand a large and sustained external shock.

Gabon

The COVID-19 pandemic and concurrent collapse in oil prices are expected to put the economy under extreme stress, particularly in a context of limited buffers. Economic growth will slow, and the fiscal and external positions will weaken, creating significant additional financing needs in 2020.