A note on ‘Single-machine scheduling for minimizing total cost with identical,asymmetrical earliness and tardiness penalties’

We point out a flaw present in a recent publication, and show how methodology can be modified to correct it.     

Hybridizing the harmony search algorithm with a spreadsheet ‘Solver’ for solving continuous engineering optimization problems

In this article, a hybrid global–local optimization algorithm is proposed to solve continuous engineering optimization problems. In the proposed algorithm, the harmony search (HS) algorithm is used as a global-search method and hybridized with a spreadsheet ‘Solver’ to improve the results of the HS algorithm. With this purpose, the hybrid HS–Solver algorithm has been proposed. In order to test the performance of the proposed hybrid HS–Solver algorithm, several unconstrained, constrained, and structural-engineering optimization problems have been solved and their results are compared with other deterministic and stochastic solution methods. Also, an empirical study has been carried out to test the performance of the proposed hybrid HS–Solver algorithm for different sets of HS solution parameters. Identified results showed that the hybrid HS–Solver algorithm requires fewer iterations and gives more effective results than other deterministic and stochastic solution algorithms.     

A note on the paper ‘Demonstrating Johnson’s algorithm via resource constrained scheduling’

In this paper, we demonstrate that the relation between two jobs defined by min{a_i, b_j} ≤ min{b_i, a_j}, used in Johnson’s theorem, is not transitive. However, both the theorem and Johnson’s algorithm are correct.     

On the ‘interior Helmholtz integral equation formulation’ in sound radiation problems

This paper discusses the accuracy of the sound radiation (Helmholtz equation) BEM analysis when the source points are located inside the vibrating surface. It is shown that when these points are arranged in such a way that they compose a fictitious internal boundary, geometrically similar to the vibrating surface, then fictitious eigenfrequencies appear at larger values than those corresponding to the eigenfrequencies of the internal boundary. In this way, the direct-BEM analysis becomes capable of treating the non-uniqueness problem in a simple and efficient practical manner, which makes the method applicable for industrial purposes. Results are presented for the spherical monopole and dipole, while discussion is extended to a similarly vibrating cube.     

Performance of carousel systems with ‘organ-pipe’ storage

It is well known that, for carousel systems, a dedicated storage, referred to as the ‘organ-pipe’ storage in the literature, is optimal with respect to the expected travel distance for processing successive requests. What remains unanswered is how to determine its performance, which is the motivation of this study. We consider bi-directional carousels under a ‘floating’ dwell point strategy. Two important performance measures considered are system capacity (maximum throughput) and job sojourn time. We also investigate the effect of activity skew on system performance.     

Mandel and Cryer problems of fluid-saturated foams with negative Poisson’s ratio

Summary. Professor Lakes created foams with negative Poissons ratios in 1987. Since then he has examined interesting and fantastic characteristics of such foams and proposed their realistic and future possible applications. The present study was motivated by our interest in how such a foam behaves for a sudden loading if it is saturated with fluid. To highlight mechanical interactions between elastic deformation of such a foam and diffusion of the saturating fluid, we solved four problems in a unified manner: 2D and 3D, Cryer and Mandel problems. It is found that for all these problems the pore fluid pressure near the sample center climbs up from its initial pressure and then declines and vanishes; its peak is much higher for negative Poissons ratios, that is, much more remarkable Mandel-Cryer effect. Stress components such as tangential stress also show similar behavior, and the tangential stress has tension near the sample surface in spite of compressive loading. It is also found that for the step-like axial compression the Mandel cylinder sample laterally expands immediately after the loading, then shrinks and finally becomes thinner than its original thickness; a possible application is proposed.     

Dynamic pricing with ‘BOGO’ promotion in revenue management

We consider a dynamic pricing problem when a seller, facing uncertain demands, sells a single product in a finite horizon. The seller actively adopts dynamic pricing and quantity discount schemes. The proposed model is based on the assumption that each customer has random reservation prices and the purchase size depends on the posted price and discount. We particularly focus on the widely adopted promotional schemes ‘buy one get one free’ and ‘50% off’ and study the optimal strategic choices of the seller. Analytical results together with numerical experiments are presented to help us obtain managerial insights. Additional numerical results for a generalised model are provided so as to examine the effectiveness of promotional schemes.     

Some comments on Chen et al. ‘Production scheduling optimization algorithm for the hot rolling processes’

Blades play an important role in aviation engine, gas turbine and jet engine. Inspecting the blade by optical method is a meaningful work in manufacturing industry. During optical inspecting process, one common problem encountered is that the scanned point cloud is large scale and noisy. In this paper, we present a systematic introduction of simplification, smoothing and parameter extraction with respect to point-sampled blades. First, the moving least square surface is applied to create a geometric deviation, which is used to subdivide and cluster the point cloud. Then, the information entropy in k-neighbourhood is defined to smooth point-sampled surface, meanwhile preserving high curvature feature. Furthermore, the computation method of single/multi section parameters is presented, and test experiments are performed in iCloud3D Blade V1.0. Experimental results demonstrate the feasibility and effectiveness of the proposed method.     

A note on ‘A multigoal heuristic for facilities desiǵn problems: MUGHAL’

We compare the performance of a set of rectangular layout heuristics on the basis of their packing densities and time performance, with a view to increase their applicability in manufacturing situations. Among the techniques is a class of heuristics introduced by the authors in an earlier work (Israni And Sanders, 1982). The experimental comparison is made over two attributes defined for the bill of materials; the area and the aspect ratio distributions of the pieces. In addition, some of the heuristics considered permit limited human intervention. Our study shows that the two attributes play a significant part in determining the performance of a heuristic. Length-sorted heuristics are found to perform differently as a class from height-sorted heuristics. The study shows that human intervention, even in limited amounts, usually improves the quality of a solution substantially. The heuristics' worst case time complexities are presented. For certain specific regions of the attributes, the best heuristic has been identified.     

Visible light-regulated BiVO4-based micromotor with biomimetic ‘predator-bait’ behavior

Journal of Materials Science - Inspired by the swarming behavior of various bacteria in nature, light-driven micromotor with collective behavior has attracted a great deal of attention, which will...     

A novel shortened electrospun nanofiber modified with a ‘concentrated’ polymer brush

Abstract

We report the fabrication of shortened electrospun polymer fibers with a well-defined concentrated polymer brush. We first prepared electrospun nanofibers from a random copolymer of styrene and 4-vinylbenzyl 2-bromopropionate, with number-average molecular weight M_n=105 200 and weight-average molecular weight M_w=296 700 (M_w/M_n=2.82). The fibers had a diameter of 593±74 nm and contained initiating sites for surface-initiated atom transfer radical polymerization (SI-ATRP). Then, SI-ATRP of hydrophilic styrene sodium sulfonate (SSNa) was carried out in the presence of a free initiator and the hydrophobic fibers. Gel permeation chromatography confirmed that M_n and M_w/M_n values were almost the same for free polymers and graft polymers. M_n agreed well with the theoretical prediction, and M_w/M_n was relatively low (<1.3) in all the examined cases, indicating that this polymerization proceeded in a living manner. Using the values of the graft amount measured by Fourier transform infrared spectroscopy, the surface area, and M_n, we calculated the graft density σ as 0.22 chains nm^?2. This value was nearly equal to the density obtained on silicon wafers (σ=0.24 chains nm^?2), which is categorized into the concentrated brush regime. Finally, we mechanically cut the fibers with a concentrated poly(SSNa) brush by a homogenizer. With increasing cutting time, the fiber length became shorter and more homogenous (11±17 μm after 3 h). The shortened fibers exhibited excellent water dispersibility owing to the hydrophilic poly(SSNa) brush layer.     

Experimental realization of ‘universal homodyne tomography’ with a single local oscillator

We report preliminary experimental measurement of the twin-beam quantum state via optical homodyne tomography using a single local oscillator. The experiment is a realization of the recently reported ‘universal homodyne tomography’ technique. The results agree well with theoretical predictions and reveal the non-classical photon-number correlation between the signal and idler photons of the twin-beam state.     

When a journal is both at the ‘top’ and the ‘bottom’: the illogicality of conflating citation-based metrics with quality

Scientometrics - The ‘quality’, ‘prestige’, and ‘impact’ of a scholarly journal is largely determined by the number of citations its articles receive....