排序方式: 共有32条查询结果,搜索用时 9 毫秒
1.
S. Appel A. Volman L. Houben Y. Gelbstein M. Bar Sadan 《Journal of Materials Science》2014,49(21):7353-7359
Layered transition metal di-chalcogenide (TMD) materials exhibit a unique combination of structural anisotropy combined with rich chemistry that confers controllability over physical properties such as bandgap and magnetism. Most research in this area is focused on single layers that are technologically challenging to produce, especially when trying to dope and alloy the host lattice. In this work, we use MoS2 flakes as a model system for the production of deliberately oriented films for practical applications in which anisotropic materials are required. The proposed production method combines ball milling with exfoliation in solution of MoS2 flakes, followed by their arrangement on a large centimeter-scale substrate by a simple and non-expensive procedure. The results show that the level of orientation achieved using the proposed system is as good as that of materials that were pressed and subjected to thermal treatment. The ball milling and exfoliation processes maintain the original crystalline structure of the MoS2 flakes, and the XRD results show that additional crystallographic phases were not produced. Lattice parameters are preserved, which verifies that other species such as water molecules did not intercalate into the MoS2 molecules. The proposed method of producing oriented films is universal, and as such, it is useful both for pure materials and for mixtures of compounds, the latter of which can be used to produce films with specifically tailored physical properties. 相似文献
2.
The facility layout problem (FLP) with unequal area departments is a very hard problem to be optimally solved. In this article, a hybrid particle swarm optimization (PSO) and local search approach is proposed to solve the FLP with unequal area departments. The flexible bay structure (FBS), which is a very common layout in manufacturing and retail facilities, is used. Furthermore, the FBS is relaxed by allowing empty spaces in bays, which results in more flexibility while assigning departments in bays. The proposed PSO approach is used to solve the FLP instances from the literature with varying sizes. The comparative results show that the PSO approach is very promising and able to find the previously known-optimal solutions in very short CPU times. In addition, new best solutions have been found for some test problems. Improvements have been achieved by allowing partially filled bays. 相似文献
3.
A mutation operator is critical for the performance of a clonal selection algorithm (CSA) since it diversifies the search directions and avoids early convergence to local optima. This article introduces a CSA approach for the unequal area facility layout problem (UAFLP) with flexible bay structure. A new encoding, the use of mutation types with different combinations, and different static and dynamic mutation application strategies are also proposed. In addition, a guideline in parameter optimization of the CSA is provided. An experimental study is performed on five cases of the UAFLP. It is concluded that the hypermutation types studied in this article, especially the inverse mutation followed by pairwise mutation, can be used to obtain good results within short computation times. 相似文献
4.
Tuncay Simsek Mustafa Baris Arun K. Chattopadhyay Sadan Ozcan Adnan Akkurt 《Transactions of the Indian Institute of Metals》2018,71(8):1885-1896
To improve mechanical properties of S2355JR carbon steel, pre-synthesized ZrB2 nanocrystals were used to coat the metal surface by laser cladding using 2000 W CO2 laser. ZrB2 nanocrystals were synthesized by mechanochemical process. The effect of laser power on the coating layers was examined for optimizing the most effective coating conditions. Microstructural studies were carried out using optical microscope, scanning electron microscope and X-ray diffraction to analyze phase structures of the coated layers. Mechanical characteristics of the laser coated layers were evaluated by studying microhardness, wear and scratch resistance properties. Maximum hardness of the coated layers was observed while cladding with 75 and 125 W laser powers, when other processing parameters and conditions were kept at optimum levels. EDS analysis of these laser cladded layers indicated the formation of complex boro-nitrides, nitrides and carbides of Zr and Fe that contributed to vast increase in hardness of the laser-clad coating on S2355JR steel. Depending upon the laser powers used, the thickness of the coated layers was found to be in the range of 15–37 µm. The wear and micro-scratch tests results revealed significant improvement in wear properties. 相似文献
5.
Nanocrystalline manganese ferrites (MnFe2O4) have been synthesized by direct milling of metallic manganese (Mn) and iron (Fe) powders in distilled water (H2O). In order to overcome the limitation of wet milling, dry milling procedure has also been utilized to reduce crystallite size. The effects of milling time on the formation and crystallite size of wet milled MnFe2O4 nanoparticles have been investigated. It has been observed that single phase 18.4 nm nanocrystalline MnFe2O4 is obtained after 24 h milling at 400 rpm. Further milling caused deformation of the structure as well as increased crystallite size. With the aim of reducing the crystallite size of 18.4 nm, MnFe2O4 sample dry milling has been implemented for 2 and 4 h at 300 rpm. As a result, the crystallite size has been reduced to 12.4 and 8.7 nm, respectively. Effects of the crystalline sizes on magnetic properties were also investigated. Magnetization results clearly demonstrated that crystallite size has much more effect on the magnetic properties than average particle size. 相似文献
6.
Abdullah KonakSadan Kulturel-Konak Gregory Levitin 《Reliability Engineering & System Safety》2012,98(1):24-34
This paper considers the optimal element sequencing in a linear multi-state multiple sliding window system that consists of n linearly ordered multi-state elements. Each multi-state element can have different states: from complete failure up to perfect functioning. A performance rate is associated with each state. The failure of type i in the system occurs if for any i (1≤i≤I) the cumulative performance of any ri consecutive elements is lower than wi. The element sequence strongly affects the probability of any type of system failure. The sequence that minimizes the probability of certain type of failure can provide high probability of other types of failures. Therefore the optimization problem for the multiple sliding window system is essentially multi-objective. The paper formulates and solves the multi-objective optimization problem for the multiple sliding window systems. A multi-objective Genetic Algorithm is used as the optimization engine. Illustrative examples are presented. 相似文献
7.
This work presents an experimental methodology for the measurement of interfacial energy (γSP) and work of adhesion (W
ad) of a metal–ceramic interface. A thin Au film was dewetted on the basal surface of sapphire substrates to form submicron-sized
particles, which were analyzed using the Winterbottom method to determine the equilibrated particle–substrate solid–solid
interfacial energy. Electron microscopy showed that a large portion of the particles contained grain boundaries, while all
of the single crystalline particles had three distinct morphologies and orientations with the substrate. Two orientation relationships
were determined from transmission electron microscopy, for which the interfacial energy in air at 1000 °C was determined:
Au (111)–sapphire (0001): γSP = 2.15 ± 0.04 J/m2, W
ad = 0.49 ± 0.04 J/m2; Au (100)–sapphire (0001): 2.18 ± 0.06 J/m2, W
ad = 0.55 ± 0.07 J/m2. 相似文献
8.
Nese Kavasoglu Cem Tozlu Osman Pakma A. Sertap Kavasoglu Sadan Ozden Bengul Metin Ozcan Birgi Sener Oktik 《Synthetic Metals》2009,159(17-18):1880-1884
The Poly(4-vinyl phenol) insulator layer was grown by spin coating technique onto p-Si substrate. Diode ideality factor (n), insulator layer thickness (δ), space charge region width (WD), interface state density (Nss), series resistance (Rs), acceptor concentration (NA) of the Au/Poly(4-vinyl phenol)/p-Si structure have been extracted from the current–voltage (I–V), frequency dependent capacitance–voltage (C–V) and conductance–voltage (G–V) measurements. It is pointed out that the interface states lead to deviation of the ideality factor value from 1 and frequency dispersion of the C–V characteristics. Nss profiles as a function of (Ess−Ev) obtained using I–V and low frequency C–V measurements are in good agreement. Nss values varying between 1012 and 1013 eV−1 cm−2 mean that Poly(4-vinyl phenol) is a candidate for insulator layer forming on Si as powerful as SiN4, SnO2, TiO2. 相似文献
9.
The milled implant-supported prosthesis offers the benefits of fixed and removable restorations. Its infrastructure provides the same rigidity as the fixed restoration, due to the precise fit to the superstructure that is removable to promote adequate access for hygiene, yet provides lip support and maintains close contact with the soft tissues. These advantages enhance phonetics, aesthetics, correct lip support, and maintenance. The learning objective of this article is to discuss the indications for milled implant-supported restorations, review the scientific background of materials and techniques utilized, and describe the clinical and laboratory procedures involved. An uncomplicated and cost-effective impression technique is outlined, and the numerous steps of infra- and superstructure fabrication are presented. 相似文献
10.
Sadan Kulturel-Konak 《Journal of Intelligent Manufacturing》2007,18(2):273-284
Production uncertainty is one of the most challenging aspects in manufacturing environments in the 21st century. The next
generation of intelligent manufacturing is dynamically depending on the production requirements, and success in designing
agile facilities is closely related to what extent these requirements are satisfied. This paper presents the most recent advancements
in designing robust and flexible facilities under uncertainty. The focus is on exploring the way uncertainty is incorporated
in facility design, namely dynamic and stochastic facility layout problems. Recent approaches are explored and categorized
in detail, and previous approaches are briefly reviewed in the related categories. Furthermore, research avenues warranting
exploration in the emerging field of facility design are also discussed. 相似文献