421 research outputs found
An Interactive Approach Based on Alternative Achievement Scale and Alternative Comprehensive Scale for Multiple Attribute Decision Making under Linguistic Environment
The aim of this paper is to develop an interactive approach for multiple attribute decision making with incomplete
weight information under linguistic environment. Some of the concepts are defined, such as the distance between
two 2-tuple linguistic variables, the expectation level of alternative, the achievement scale, the alternative
comprehensive scale under linguistic environment. Based on these concepts, we establish some linear programming
models, through which the decision maker interacts with the analyst. Furthermore, we establish a practical
interactive approach for selecting the most desirable alternative(s). The interactive process can be realized by
giving and revising the achievement scale and comprehensive scale of alternatives till the achievement scale and
the comprehensive scale are achieved to the decision maker’s request. Finally, an illustrative example is also given.The author is very grateful to the associated editor and two anonymous referees for their insightful and constructive comments and suggestions that have led to an improved version of this paper. This work was partly supported by the National Natural Science Foundation of China (No. 90924027, No. 71101043), National Basic Research Program of China (973 Program, No. 2010C B951104), Key Program of National Social Science Foundation of China (No. 10AJY005), College Philosophy and Social Science Research Project of Jiangsu Province under Grant 2011SJD630007.Xu, Y.; Wang, H.; Palacios Marqués, D. (2013). An Interactive Approach Based on Alternative Achievement Scale and Alternative Comprehensive Scale for Multiple Attribute Decision Making under Linguistic Environment. International Journal of Computational Intelligence Systems. 6(1):87-95. https://doi.org/10.1080/18756891.2013.756226S87956
The Design and Numerical Study of a 2MWh Molten Salt Thermocline Tank
AbstractThe two tank molten salt thermal storage system is widely used in the commercialized solar thermal power plant. However, the thermocline storage system with a low-cost filler material is a more economically feasible option. In this study, a transient two-dimensional and two-temperature model is developed to investigate the heat transfer and fluid dynamics in a molten salt thermocline thermal storage system. After model validation, the effects of inlet flow boundary condition and storage medium properties including fluid and solid materials on the thermal performance of thermocline storage system are investigated. The results show that thermoclne thickness increases slowest with solar salt as heat transfer fluid (HTF) and Cofalit® as solid material in the thermocline tank. Any non-uniformity in the inlet velocity flow would only enhance mixing and widen the thermocline appreciably, which contributes to the loss of thermodynamic availability of stored energy. The thermocline thickness increases with the non-uniformity of the inlet velocity boundary condition. So smaller non-uniformity of inlet flow is better in non-uniform flow though it may causes larger fluctuations in average outlet temperature. Smaller inlet mass flow rate is better for the thermocline storage tank, while it also causes smaller discharging power. With the chosen basic design parameters such as fluid and solid materials, the size of a 2MWh thermocline tank is determined by a simple one-dimensional design method. Tank with larger H/D ratio has higher discharge efficiency. It helps to figure out the thermal stratification mechanism of a storage tank and thereby to determine optimum design and operating conditions
A novel layer-structured PtN₂: first-principles calculations
Platinum nitride as the first successfully synthesized noble metal nitride shows superior mechanical properties and exotic electronic structure that rival those of conventional transition metal nitrides. In the past diverse crystal structures have been proposed to understand its unusual properties. However, very few works pay attention to the dynamic stability of these phases. Here, we examine the potential structures of platinum nitride with a chemical composition of PtN₂ by utilizing a widely adopted evolutionary methodology for crystal structure prediction. Except reproducing the previously proposed phases, we also identify a Pmmm symmetric novel layer structure with a low formation enthalpy that is slightly lower than those of marcasite and CoSb₂ structures but slightly higher than that of pyrite structure. The elastic constants and the lattice dynamical calculations show that this layer-structured PtN₂ is mechanically and dynamically stable. The calculated band structures suggest this new phase together with the simple tetragonal phase are metallic, while other phases are insulators. In addition, it is found that the fluorite structure is dynamically unstable by the phonon spectrum calculations, although it is mechanically stable as suggested by calculated elastic constants.Розглянуто потенційні структури нітриду платини з хімічним складом PtN₂, використовуючи широко прийняту еволюційну методологію прогнозування кристалічних структур. Крім відтворення раніше запропонованих фаз, ідентифіковано нову симетричну шарувату структуру, просторова група Pmmm, з низькою ентальпією формування, яка трохи менша, ніж ентальпії структур марказиту і CoSb₂, але дещо більша, ніж ентальпія структури піриту. Постійні пружності і динамічні розрахунки решітки показують, що цей нітрид платини (PtN₂) з шаруватою структурою механічно і динамічно стабільний. Розраховані зонні структури дозволяють припустити, що ця нова фаза разом з простою тетрагональною фазою є металічною, тоді як інші фази є діелектричні. Розрахунками фононного спектру встановлено, що структура флюориту динамічно нестабільна, хоча механічно стабільна, як передбачається розрахованими константами пружності.Рассмотрены потенциальные структуры нитрида платины с химическим составом PtN₂, используя широко принятую эволюционную методологию прогнозирования кристаллических структур. Кроме воспроизведения ранее предложенных фаз, идентифировано новую симметричную слоистую структуру, пространственная группа Pmmm, с низкой энтальпией формирования, которая немного меньше, чем энтальпии структур марказита и CoSb₂, но немного больше, чем энтальпия структуры пирита. Постоянные упругости и динамические расчеты решетки показывают, что этот нитрид платины (PtN₂) со слоистой структурой механически и динамически стабилен. Рассчитанные зонные структуры позволяют предположить, что эта новая фаза вместе с простой тетрагональной фазой является металлической, тогда как другие фазы являются диэлектрическими. Расчетами фононного спектра установлено, что структура флюорита динамически нестабильна, хотя механически стабильна, как предполагается рассчитанными константами упругости
High-pressure behaviors of carbon nanotubes
In this paper, we have reviewed the experimental and theoretical studies on pressure-induced polygonization, ovalization, racetrack–shape deformation, and polymerization of carbon nanotubes (CNTs). The corresponding electronic, optical, and mechanical changes accompanying these behaviors have been discussed. The transformations of armchair (n, n) CNT bundles (n = 2, 3, 4, 6, and 8) under hydrostatic or nonhydrostatic pressure into new carbons, including recently proposed superhard bct-C₄, Cco-C₈, and B-B1AL2R2 carbon phases have also been demonstrated. Given the diversity of CNTs from various chiralities, diameters, and arrangements, pressure-induced CNT polymerization provides a promising approach to produce numerous novel metastable carbons exhibiting unique electronic, optical, and mechanical characteristics.Розглянуто експериментальні та теоретичні дослідження з індукованою тиском полігонізації, овалізації, деформації у формі бігової доріжки і полімеризації вуглецевих нанотрубок (ВНТ). Обговорено відповідні електронні, оптичні і механічні зміни, що супроводжують ці процеси. Також продемонстровано перетворення в ВНТ у формі крісла (n, n), зібраних в пучок (n = 2, 3, 4, 6 і 8) під гідростатичним або негідростатичним тиском в нові вуглецеві алотропи, в тому числі недавно запропоновані надтверді bct-C₄, Cco-C₈ і B-B1AL2R2-вуглецеві фази. Різноманітність ВНТ з різними хіральністю, діаметрами та упаковками, а також полімеризація ВНТ, викликана тиском, забезпечує перспективний підхід для отримання численних нових метастабільних вуглецевих фаз, що демонструють унікальні електронні, оптичні і механічні характеристики.Рассмотрены экспериментальные и теоретические исследования по индуцированной давлением полигонизации, овализации, деформации в форме беговой дорожки и полимеризации углеродных нанотрубок (УНТ). Обсуждены соответствующие электронные, оптические и механические изменения, сопровождающие эти процессы. Также продемонстрированы преобразования в УНТ в форме кресла (n, n), собранных в пучок (n = 2, 3, 4, 6 и 8) под гидростатическим или негидростатическим давлением в новые углеродные аллотропы, в том числе недавно предложенные сверхтвердые bct-C₄, Cco-C₈ и B-B1AL2R2-углеродные фазы. Разнообразие УНТ с различными хиральностью, диаметрами и упаковками, а также полимеризация УНТ, вызванная давлением, обеспечивает перспективный подход для получения многочисленных новых метастабильных углеродных фаз, демонстрирующих уникальные электронные, оптические и механические характеристики
Lambda collective flow in heavy ion reactions
Collective flow of Lambda hyperons in heavy ion reactions at SIS energies is
investigated. It is found that a mean field constructed on the basis
of the quark model leads to a good description of the experimental data of the
in-plane transverse flow of 's. The attractive mean field can also
give rise to an additional "virtual" radial flow directed inwards,
which is reflected by a "concave" structure of the transverse mass spectrum of
the hyperons emitted at midrapidity. The radial flow is
found to exhibit a strong mass dependence: The flow is visible in the Ni+Ni
system, but is strongly reduced in the system of Au on Au.Comment: 18 pages LeTex, using Elsevier style, 6 PS-figures, accepted for
publication in Nuclear Physics
Ultrastrong conductive in situ composite composed of nanodiamond incoherently embedded in disordered multilayer graphene
Traditional ceramics or metals cannot simultaneously achieve ultrahigh strength and high electrical conductivity. The elemental carbon can form a variety of allotropes with entirely different physical properties, providing versatility for tuning mechanical and electrical properties in a wide range. Here, by precisely controlling the extent of transformation of amorphous carbon into diamond within a narrow temperature–pressure range, we synthesize an in situ composite consisting of ultrafine nanodiamond homogeneously dispersed in disordered multilayer graphene with incoherent interfaces, which demonstrates a Knoop hardness of up to ~53 GPa, a compressive strength of up to ~54 GPa and an electrical conductivity of 670–1,240 S m(–1) at room temperature. With atomically resolving interface structures and molecular dynamics simulations, we reveal that amorphous carbon transforms into diamond through a nucleation process via a local rearrangement of carbon atoms and diffusion-driven growth, different from the transformation of graphite into diamond. The complex bonding between the diamond-like and graphite-like components greatly improves the mechanical properties of the composite. This superhard, ultrastrong, conductive elemental carbon composite has comprehensive properties that are superior to those of the known conductive ceramics and C/C composites. The intermediate hybridization state at the interfaces also provides insights into the amorphous-to-crystalline phase transition of carbon
Cosmological distance indicators
We review three distance measurement techniques beyond the local universe:
(1) gravitational lens time delays, (2) baryon acoustic oscillation (BAO), and
(3) HI intensity mapping. We describe the principles and theory behind each
method, the ingredients needed for measuring such distances, the current
observational results, and future prospects. Time delays from strongly lensed
quasars currently provide constraints on with < 4% uncertainty, and with
1% within reach from ongoing surveys and efforts. Recent exciting discoveries
of strongly lensed supernovae hold great promise for time-delay cosmography.
BAO features have been detected in redshift surveys up to z <~ 0.8 with
galaxies and z ~ 2 with Ly- forest, providing precise distance
measurements and with < 2% uncertainty in flat CDM. Future BAO
surveys will probe the distance scale with percent-level precision. HI
intensity mapping has great potential to map BAO distances at z ~ 0.8 and
beyond with precisions of a few percent. The next years ahead will be exciting
as various cosmological probes reach 1% uncertainty in determining , to
assess the current tension in measurements that could indicate new
physics.Comment: Review article accepted for publication in Space Science Reviews
(Springer), 45 pages, 10 figures. Chapter of a special collection resulting
from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in
the Space Ag
Toward an internally consistent astronomical distance scale
Accurate astronomical distance determination is crucial for all fields in
astrophysics, from Galactic to cosmological scales. Despite, or perhaps because
of, significant efforts to determine accurate distances, using a wide range of
methods, tracers, and techniques, an internally consistent astronomical
distance framework has not yet been established. We review current efforts to
homogenize the Local Group's distance framework, with particular emphasis on
the potential of RR Lyrae stars as distance indicators, and attempt to extend
this in an internally consistent manner to cosmological distances. Calibration
based on Type Ia supernovae and distance determinations based on gravitational
lensing represent particularly promising approaches. We provide a positive
outlook to improvements to the status quo expected from future surveys,
missions, and facilities. Astronomical distance determination has clearly
reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press
(chapter 8 of a special collection resulting from the May 2016 ISSI-BJ
workshop on Astronomical Distance Determination in the Space Age
Updates on radiotherapy-immunotherapy combinations: Proceedings of 6th annual ImmunoRad conference.
Focal radiation therapy (RT) has attracted considerable attention as a combinatorial partner for immunotherapy (IT), largely reflecting a well-defined, predictable safety profile and at least some potential for immunostimulation. However, only a few RT-IT combinations have been tested successfully in patients with cancer, highlighting the urgent need for an improved understanding of the interaction between RT and IT in both preclinical and clinical scenarios. Every year since 2016, ImmunoRad gathers experts working at the interface between RT and IT to provide a forum for education and discussion, with the ultimate goal of fostering progress in the field at both preclinical and clinical levels. Here, we summarize the key concepts and findings presented at the Sixth Annual ImmunoRad conference
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