4,391 research outputs found
Identifying and understanding the positive impact of defects for perovskites optoelectronic devices
Defects are generally regarded to have negative impact on carrier
recombination, charge-transport and ion migration in perovskite materials,
which thus lower the efficiency and stability of perovskite optoelectronic
devices. Meanwhile, lots of efforts which focused on minimizing defects have
greatly promoted the application of perovskite materials. Then, can defects be
positive in perovskite optoelectronic devices? Herein, relying on in-depth
understanding of defect-associated effects in semiconductors, trapping of
photo-generated carriers by defects is applied to enlarge photoconductive gain
in perovskite photodetector. The record photoconductive gain, gain-bandwidth
product and detection limit were achieved in the photodetector. Exceeding the
general concept that defects are harmful, we identify a new view that the
defects can be positive in perovskite optoelectronic devices.Comment: 6 pages, 3 figure
An improved multi-objective programming with augmented ε-constraint method for hazardous waste location-routing problem
Source at https://doi.org/10.3390/ijerph13060548. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
author and source are credited.Hazardous waste location-routing problems are of importance due to the potential risk for nearby residents and the environment. In this paper, an improved mathematical formulation is developed based upon a multi-objective mixed integer programming approach. The model aims at assisting decision makers in selecting locations for different facilities including treatment plants, recycling plants and disposal sites, providing appropriate technologies for hazardous waste treatment, and routing transportation. In the model, two critical factors are taken into account: system operating costs and risk imposed on local residents, and a compensation factor is introduced to the risk objective function in order to account for the fact that the risk level imposed by one type of hazardous waste or treatment technology may significantly vary from that of other types. Besides, the policy instruments for promoting waste recycling are considered, and their influence on the costs and risk of hazardous waste management is also discussed. The model is coded and calculated in Lingo optimization solver, and the augmented ε-constraint method is employed to generate the Pareto optimal curve of the multi-objective optimization problem. The trade-off between different objectives is illustrated in the numerical experiment
Enhancing the competitiveness of manufacturers through Small-scale Intelligent Manufacturing System (SIMS): A supply chain perspective
An electronic version of the final, peer-reviewed manuscript upon acceptance for publication made publicly after an IEEE embargo period of 24 months from the date of publication.
Link to publishers version:http://doi.org/10.1109/ICITM.2017.7917904In order to survive in this competitive and ever changing market, manufacturers have to improve and enhance the competitiveness, flexibility, responsiveness and sustainability with the application of the cutting-edge technologies and innovative management methods. New concepts, i.e., Intelligent manufacturing, flexible manufacturing, agile manufacturing, network manufacturing, green manufacturing and Industry 4.0, etc., have been proposed and developed in recent years based upon the newest and most advanced manufacturing technologies and Information and Communication technologies (ICT). This paper presents a new concept: Small-scale Intelligent Manufacturing System (SIMS), and the comparison with previous concepts and the benefits of SIMS are discussed in this paper. Different from the previous research works which mainly emphasize the technological integration for improving the flexibility and intelligence of an individual manufacturing system, this paper, however, focuses on and discusses the supply chain problems arisen from a holistic perspective. The features of the supply chain for realizing small-scale intelligent production and responsive distribution are discussed, and the limitation and future works are also discussed and suggested latter in this paper
A New Two-Stage Stochastic Model for Reverse Logistics Network Design under Government Subsidy and Low-Carbon Emission Requirement
Embargoed Access, etter IEEEs generelle retningslinjer (manuscript version for OA after 24 mnths embargo from publication date)
Link to publisher's version: http://doi.org/10.1109/IEEM.2017.8289857Nowadays, increasing number of companies incorporates the reverse logistics decisions into their supply chain design in order to cope with the enforced international and national legislation and improve the resource efficiency and public image. This paper investigates a new stochastic optimization model for designing a single-period multiproduct multi-level reverse logistics system under government subsidy and low-carbon emission requirement. In order to resolve the stochastic optimization problem, a modified multi-criteria scenario-based approach is proposed to maximize the profit generation while simultaneously improve the stability of the decision-making under uncertainty. The model and solution method are tested with several numerical experiments, and managerial insights are obtained with respect to the carbon emission requirement, governmental subsidy, economy of scale, and system flexibility
Model-Independent Constraints on Lorentz Invariance Violation via the Cosmographic Approach
Since Lorentz invariance plays an important role in modern physics, it is of
interest to test the possible Lorentz invariance violation (LIV). The time-lag
(the arrival time delay between light curves in different energy bands) of
Gamma-ray bursts (GRBs) has been extensively used to this end. However, to our
best knowledge, one or more particular cosmological models were assumed {\it a
priori} in (almost) all of the relevant works in the literature. So, this makes
the results on LIV in those works model-dependent and hence not so robust in
fact. In the present work, we try to avoid this problem by using a
model-independent approach. We calculate the time delay induced by LIV with the
cosmic expansion history given in terms of cosmography, without assuming any
particular cosmological model. Then, we constrain the possible LIV with the
observational data, and find weak hints for LIV.Comment: 15 pages, 4 figures, 3 tables, revtex4; v2: discussions added, Phys.
Lett. B in pres
A green supply chain network design model for enhancing competitiveness and sustainability of companies in high north arctic regions
To survive in today's competitive and ever-changing marketplace, companies need not only to engage in their products and/or services, but also to focus on the management of the whole supply chain. Effectively managing and balancing the profitability and interconnection of each player in the supply chain will improve the overall supply chain surplus as well as individual profit. However, it is extremely difficult to simultaneously optimize several objectives in design and planning of a supply chain, i.e., cost-minimization, risk-minimization, responsiveness-maximization, etc., which are somehow conflict with one another. Furthermore, the natural and infrastructural challenges in high north arctic regions make it become much more difficult and complicated to design and develop cost-efficient, highly responsive, environmentally friendly, and sustainable supply chain network. In order to provide companies in high north arctic regions with decision support tool for the design and planning of theirs supply chain networks, a green supply chain network design (GrSCND) model is formulated in this study based on multi-objective mixed integer programming (MIP). The optimal trade-off among several conflicting objectives is the focus of this GrSCND model aiming to enhance both competitive competence and sustainability of companies and supply chains operated in high north regions. In addition, a numerical experiment is also given to present a deep insight of the GrSCND model. Copyright © 2014 International Energy and Environment Foundation -All rights reserved
An introduction of small-scale intelligent manufacturing system
Embargoed OA, manuscript version after 24 months from publishing date. Link to publishers version: http://doi.org/10.1109/SIMS.2016.7802896Manufacturing companies in Northern Peripheral and Arctic region are predominately small and medium-sized and face considerable challenges like geographical isolation and a lack of benefits offered by industrial clusters. For the ultimate goal of enhancing their competitiveness in a global market, it is imperative for companies to innovate or adopt innovations in order to quickly response to changes in market, meet customer demands, reduce time-to-market and lower cost. A novel concept for small-scale intelligent manufacturing systems (SIMS) is introduced, in which diverse methods and innovative technologies can be applied and integrated. This paper gives an introduction of SIMS, defines its design objectives, and summarizes major relevant tools, techniques and paradigms for the development of SIMS, to generate a facilitative environment for small and medium-scale manufacturing enterprises to embrace new and innovative technologies
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