Maximizing production rate and workload smoothing in assembly lines using particle swarm optimization

Particle swarm optimization (PSO) one of the latest developed population heuristics has rarely been applied in production and operations management (POM) optimization problems. A possible reason for this absence is that, PSO was introduced as global optimizer over continuous spaces, while a large set of POM problems are of combinatorial nature with discrete decision variables. PSO evolves floating-point vectors (called particles) and thus, its application to POM problems whose solutions are usually presented by permutations of integers is not straightforward. This paper presents a novel method based on PSO for the simple assembly line balancing problem (SALBP), a well-known NP-hard POM problem. Two criteria are simultaneously considered for optimization: to maximize the production rate of the line (equivalently to minimize the cycle time), and to maximize the workload smoothing (i.e. to distribute the workload evenly as possible to the workstations of the assembly line). Emphasis is given on seeking a set of diverse Pareto optimal solutions for the bi-criteria SALBP. Extensive experiments carried out on multiple test-beds problems taken from the open literature are reported and discussed. Comparisons between the proposed PSO algorithm and two existing multi-objective population heuristics show a quite promising higher performance for the proposed approach.Particle swarm optimization Assembly line balancing Multi-objective optimization Evolutionary algorithms Meta-heuristics

The contemporary use of electron microscopy in the diagnosis of ciliary disorders and sperm centriolar abnormalities

Cilia and flagella are hair-like structures which extend from the cell membrane and are involved in a variety of biological functions in eukaryotes. Cilia are found in a wide range of human tissues and cell types including: the epithelium of the upper and lower respiratory tracts, the epithelium of the kidney, bile and pancreatic ducts, the embryonic node, and the ependymal cells in the brain and in the oviduct epithelium

Clinical features of primary ciliary dyskinesia in Cyprus with emphasis on lobectomized patients

Background: Despite the manifestations of primary ciliary dyskinesia (PCD) in early life, the diagnosis is often much delayed. Since 1998 in Cyprus, we have established the only national diagnostic and clinical referral center for PCD. Objective: To review the phenotypic features at presentation of PCD patients in Cyprus in relation to age at diagnosis, with emphasis on previously lobectomised patients. Methods: The medical records of the diagnosed PCD patients were retrospectively reviewed to obtain clinical data on presentation. Results: Thirty patients, aged 13.9 years (range 0.1, 58.4 years), were diagnosed with PCD. Twelve of them presented after the age of 18. The most common manifestations were chronic cough (100%), chronic rhinorrhea (96.7%), sputum production (92.9%), laterality defects (63.3%), a history of pneumonia (53.3%) and neonatal respiratory distress (50%). A history of lobectomy in the past was recorded in 16.7% (5 patients). Patients who presented in adulthood had significantly higher frequency of lobectomy (41.7% vs 0%, p-value=0.006) and had more frequently low FEV1 (58.3% vs 0%, p-value=0.015) than those who presented before. Serial measurements of FEV1 and FVC indicated significantly lower intercepts in lobectomised compared to the adult non-lobectomised patients both in terms of FEV1 (-4.90 vs -1.80, p-value=0.022) and FVC (-5.43 vs -1.91, p-value=0.029) z-score levels. Change in FEV1 and FVC across time was not statistically significant in either group. Conclusions: PCD often remains undiagnosed up to adulthood accompanied by appearance of advanced lung disease. Performance of lobectomies seems to be a poor prognostic factor for PCD in adulthood