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排序方式: 共有2308条查询结果,搜索用时 187 毫秒
31.
Economic selection of process mean and lot‐sizing decisions for multi‐newsvendor supply chain 下载免费PDF全文
M. A. Darwish Majid M. Aldaihani 《International Transactions in Operational Research》2015,22(6):1055-1070
Two related problems are integrated in this paper, the first is the targeting problem and another is production/inventory decisions in a supply chain. The supply chain under consideration consists of a supplier of raw material, a single producer, and multiple newsvendors. The producer can adjust the process mean before starting the production run. Once set to a certain target value, the process mean is not changed until the production lot is completed. At the end of a production run, the producer screens the lot and uses specification limits to evaluate the quality of the item. Nonconforming items are scrapped with no salvage value; however, conforming items are delivered to newsvendors who are subjected to random demand. If demand on a newsvendor in a season is lower than anticipated, surplus items will be returned to the producer at a certain transportation cost. We first develop a mathematical model that maximizes the expected total profit of the supply chain. Then, a table for two special functions is devised to simplify the solution method and is used to find the optimal solution of the proposed model. We also study the significance of this integration by comparing the performance of the proposed model with an independent model where the process mean selection and lot‐sizing decisions are found separately. 相似文献
32.
Stability Margin Determination of Linear Discrete‐Time Systems Described By Fuzzy Convex Sets Uncertainty 下载免费PDF全文
This paper proposes a new method for determining the stability margin of uncertain linear discrete‐time systems with uncertainty described by fuzzy convex sets. Nonsymmetrical triangular membership functions describing the uncertainty of characteristic polynomial coefficients are considered. This method is based on transformation of the uncertain discrete systems to the continuous time area and generalization of Kharitonov theorem for determining the uncommon minimum confidence level that guarantees stability of the system. 相似文献
33.
This study describes the successful separation of acrylonitrile (ACN) from dilute aqueous streams using pervaporation process. The influences of ACN feed concentration, permeate pressure, operating temperature, feed flow rate and membrane thickness on the membrane separation performance were investigated. The results showed that with an increase in ACN concentration in the feed solution, the permeation flux of ACN increased while the enrichment factor decreased. It was also indicated that increasing the permeate pressure reduced the driving force for mass transfer and consequently the permeation flux dropped while the enrichment factor enhanced. Polydimethylsiloxane membranes used in this study showed very good properties in the separation process, leading to enrichment factors in the range of 70-140. Furthermore, the activation energy for pervaporation of both ACN and water calculated from Arrhenius plot indicated that the permeation of water through the membrane was more temperature dependant than ACN. 相似文献
34.
Snake robots are mostly designed based on single mode locomotion. However, single mode gait most likely could not work effectively when the robot is subject to an unstructured working environment with different measures of terrain complexity. As a solution, mixed mode locomotion is proposed in this paper by synchronizing two types of gaits known as serpentine and wriggler gaits used for non-constricted and narrow space environments, respectively, but for straight line locomotion only. A gait transition algorithm is developed to efficiently change the gait from one to another. This study includes the investigation on kinematics analysis followed by dynamics analysis while considering related structural constraints for both gaits. The approach utilizes the speed of the serpentine gait for open area locomotion and exploits the narrow space access capability of the wriggler gait. Hence, it can increase motion flexibility in view of the fact that the robot is able to change its mode of locomotion according to the working environment. 相似文献
35.
Steady and unsteady flow analysis in microdiffusers and micropumps: a critical review 总被引:3,自引:0,他引:3
Majid Nabavi 《Microfluidics and nanofluidics》2009,7(5):599-619
In recent research, there has been a growing interest in the analysis of flow through microdiffusers and micropumps in order
to characterize and optimize the performance of these devices. In this review, the recent advances in the numerical and experimental
analysis of the steady and pulsating flows through microdiffusers and valveless micropumps are surveyed. The differences between
the performance of microdiffusers and micropumps in steady and unsteady flow regimes are described. Qualitative and quantitative
discussions of the effects of different design parameters on the performance of microdiffusers and valveless micropumps in
both steady and unsteady flow regimes along with the contradictory results reported in the literature in this regard are provided.
In addition, a summary of the latest micropump technologies along with the advantages and disadvantages of each mechanism
with the emphasis on the innovative and less-reviewed micropumps are presented. Two important types of fixed microvalves,
as part of valveless micropumps are described in details. Experimental flow visualization of steady and pulsating flows through
microdiffusers and micropumps as a useful tool for better understanding the underlying micro-fluid dynamics is discussed.
The present review reveals that there are many possible areas of research in the field of steady and unsteady flows through
microdiffusers and micropumps in order to understand the effects of all important design parameters on the performance of
these devices. 相似文献
36.
Ali Eshaghi Mohammad Mashreghi Mahere Rezazade Bazaz Masoud HomayouniTabrizi Majid Darroudi 《IET nanobiotechnology / IET》2017,11(5):517
The aim of this study is to introduce natural‐based polymers, chitosan and starch, to design a remedial nanocomposite, comprising of cerium oxide nanoparticles and silver nanoparticles, to investigate their effects in accelerating wound healing and in wound microbial load. Cerium oxide nanoparticles synthesized in starch solution added to the colloidal dispersion of synthesized silver nanoparticles in chitosan to make a three‐component nanomaterial. Mice were anaesthetized and two parallel full‐thickness round wounds were excised under aseptic conditions with the help of sterile dermal biopsy punch. Furthermore, effects of silver‐chitosan and silver‐cerium‐chitosan nanocomposite had evaluated on rate of wound closure and collagen density and on microbial load of wound in full‐thickness model. Results showed that both silver chitosan and silver‐cerium‐chitosan had significant impact on acceleration of wound closure and collagen content and on reduction of wound microbial load in comparison with control group, which was, received no treatments. However, the silver‐cerium‐chitosan nanocomposite is more potent than silver‐chitosan group and control group in wound closure. The wound healing effects of silver‐cerium‐chitosan nanocomposite are due to unique features of its three components and this nanocomposite promises impressive remedies for clinical application.Inspec keywords: wounds, nanocomposites, nanomedicine, nanoparticles, proteins, cerium, silver, polymers, colloids, patient treatmentOther keywords: biopolymer‐based nanocomposite wound dressing, wound healing properties, wound microbial load, natural‐based polymers, chitosan, remedial nanocomposite, cerium oxide nanoparticles, nanoceria, silver nanoparticles, starch solution, three‐component nanomaterial, synthesised silver nanoparticles, ketamine intraperitoneal injection, silver‐cerium‐chitosan nanocomposite, wound closure, collagen density, wound healing effects, wound care, aseptic conditions, sterile dermal biopsy punch, Ag‐Ce 相似文献
37.
38.
Bioinspired Nacre‐Like Ceramic with Nickel Inclusions Fabricated by Electroless Plating and Spark Plasma Sintering 下载免费PDF全文
Zhe Xu Jiacheng Huang Cheng Zhang Soheil Daryadel Ali Behroozfar Brandon McWilliams Benjamin Boesl Arvind Agarwal Majid Minary‐Jolandan 《Advanced Engineering Materials》2018,20(5)
39.
On the Structure of Amorphous Mesoporous Silica Nanoparticles by Aberration‐Corrected STEM 下载免费PDF全文
Sebastian Calderon V Tânia Ribeiro José Paulo S. Farinha Carlos Baleizão Paulo J. Ferreira 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(40)
Mesoporous silica materials have demonstrated a vast spectrum of applications, stimulating an intensive field of study due to their potential use as nanocarriers. Nonetheless, when produced at the nanoscale, their structural characterization is hindered due to the re‐arrangement of the pores. To address this issue, this work combines molecular dynamics simulations with electron microscopy computer simulations and experimental results to provide an insight into the structure of amorphous mesoporous silica nanoparticles. The amorphous silica model is prepared using a simple melt‐quench molecular dynamics method, while the reconstruction of the mesoporous nanoparticles is carried out using a methodology to avoid false symmetry in the final model. Simulated scanning transmission electron microscopy images are compared with experimental images, revealing the existence of structural domains, created by the misalignment of the pores to compensate the surface tension of these spherical nanoparticles. 相似文献
40.
Multi-level (ML) quantum logic can potentially reduce the number of inputs/outputs or quantum cells in a quantum circuit which
is a limitation in current quantum technology. In this paper we propose theorems about ML-quantum and reversible logic circuits.
New efficient implementations for some basic controlled ML-quantum logic gates, such as three-qudit controlled NOT, Cycle,
and Self Shift gates are proposed. We also propose lemmas about r-level quantum arrays and the number of required gates for an arbitrary n-qudit ML gate. An equivalent definition of quantum cost (QC) of binary quantum gates for ML-quantum gates is introduced and
QC of controlled quantum gates is calculated. 相似文献