Flexible job-shop scheduling problems with ‘AND’/‘OR’ precedence constraints

The purpose of this research is to solve flexible job-shop scheduling problems with ‘AND’/‘OR’ precedence constraints in the operations. We first formulate the problem as a Mixed-Integer Linear Program (MILP). The MILP can be used to compute optimal solutions for small-sized problems. We also developed a heuristic algorithm that can obtain a good solution for the problem regardless of its size. Moreover, we have developed a representation and schedule builder that always produces a legal and feasible solution for the problem, and developed genetic and tabu search algorithms based on the proposed schedule builder. The results of the computational experiments show that the developed meta-heuristics are very effective.     

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.     

The evaluation of energy–environmental efficiency of China’s industrial sector: based on Super-SBM model

Clean Technologies and Environmental Policy - With the process of urbanization and industrialization, a growing attention has been paid to the energy–environmental efficiency in China’s...     

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.     

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....     

Extending the product portfolio with ‘devolved manufacturing’: methodology and case studies

Current research by the developers of rapid prototyping systems is generally focused on improvements in cost, speed and materials to create truly economic and practical economic rapid manufacturing (RM) machines. In addition to being potentially smarter/faster/cheaper replacements for existing manufacturing technologies, the next generation of these machines will provide opportunities not only for the design and fabrication of products without traditional constraints but also for organizing manufacturing activities in new, innovative and previously undreamt of ways. This paper outlines a novel devolved manufacturing (DM) ‘factory-less’ approach to e-manufacturing, which integrates mass customization (MC) concepts, RM technologies and the communication opportunities of the Internet/World Wide Web, describes two case studies of different DM implementations and discusses the limitations and appropriateness of each, and, finally, draws some conclusions about the technical, manufacturing and business challenges involved.     

International collaboration of three ‘giants’ with the G7 countries in emerging nanobiopharmaceuticals

Nanobiopharmaceuticals is a hopeful research domain from recent scientific advances with massive marketable potential. Although some researchers have studied international collaboration from some aspects, few articles are as comprehensive as this article to consider international cooperation from so many different aspects. We lay more emphasis on international collaboration in the field of nanobiopharmaceuticals involving China. Incremental citation impact values show that in order to move forward and improve the overall competitiveness in the field, China requires to carry out more international collaboration in the field, especially with USA, Germany, and England. Startlingly, multinational collaboration does not sway Chinese citation impact as much as we anticipate in the field. China has reached the first rank in the world in terms of publication amount per year in the field in 2009. Few papers about international collaboration compare small world phenomenon. We use small world quotient to find that it is important for Chinese international co-authors to strengthen to cultivate a cooperation networks in which a node’s partners are also buddies to each other.     

A note on ‘A two-level supply chain with consignment stock agreement and stock-dependent demand’

This note points out that the cost functions within Zanoni and Jaber [Zanoni, S. and M. Y. Jaber. 2015. “A Two-level Supply Chain with Consignment Stock Agreement and Stock-dependent Demand.” International Journal of Production Research 53: 3561–3572] might be incorrect due to misuse of demand representation. By incorporating Braglia and Zavanella’s consignment stock model and relaxing the zero-inventory reordering constraint, Zanoni and Jaber made extensions of the integrated vendor–buyer supply chain with stock-dependent demand in Sajadieh, Thorstenson, and Akbari Jokar’s proposed model. However, Sajadieh, Thorstenson, and Akbari Jokar’s model has different scenarios than Braglia and Zavanella’s model, and these inconsistencies cause false formulation in Zanoni and Jaber’s paper. In this note, we first formulate the justified cost functions and then present characteristics of the corrected model.     

Extended depth of field with the optimal ‘0, π’ binary phase pupil mask

A ‘0, π’ phase pupil mask was developed to extend the depth of the field of a circularly symmetric optical imaging system. A global search algorithm was used to seek an optimal pupil mask which provides the largest spatial frequency band in a certain desired contrast value. The modulation transfer function curves and the normalized point spread function figures of the imaging system with the optimal mask were analyzed. The results show that the imaging system has a high resolution in a long frequency band and can obtain clear images without any post-processing. The experimental results also demonstrate that the depth of field of the imaging system is extended sixfold successfully.     

用创意玩公益!‘乐·色起义创意垃圾桶设计大赛’颁奖盛典在京举行

日前，由年轻时尚的公益组织——CNature（自然景象环境保护协会http：//www．cnature．org），携手国内最大的创意门户网站——视觉中国推出的“乐·色起义创意垃圾桶设计大赛”颁奖盛典，在位于东三环双井桥东北角的乐成购物中心30层阳光大厅正式举行。