2,097 research outputs found

    On Agarwal–Pang-type integral inequalities

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    We establish some new Agarwal–Pang-type inequalities including second-order partial derivatives. In special cases, our results yield some correlated results and provide new estimates for the inequalities of this type.Встановлено деякi новi нерiвностi типу Агарвала – Панга, що мiстять частиннi похiднi другого порядку. В окремих випадках iз одержаних результатiв випливають деякi пов’язанi результати та новi оцiнки для нерiвностей цього типу

    Transparent and Conducting Boron Doped ZnO Thin Films Grown By Aerosol Assisted Chemical Vapor Deposition

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    ZnO based transparent conducting oxides are important as they provide an alternative to the more expensive Sn:In2O3 that currently dominates the industry. Here, we investigate B-doped ZnO thin films grown via aerosol assisted chemical vapour deposition. B:ZnO films were produced from zinc acetate and triethylborane using either tetrahydrofuran or methanol (MeOH) as the solvent. The lowest resistivity of 5.1 x 10-3 .cm along with a visible light transmittance of ~75 - 80% was achieved when using MeOH as the solvent. XRD analysis only detected the wurtzite phase of ZnO suggesting successful solid solution formation with B3+ substituting Zn2+ sites in the lattice. Refinement of the XRD patterns showed minimal distortion to the ZnO unit cell upon doping when MeOH was the solvent due to the immiscibility of the [BEt3] solution (1.0M solution in hexane) in methanol that limited the amount of B going into the films, thus preventing excessive doping

    An E-Readiness Assesment Framework and Two Field Studies

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    Although e-business is increasingly important to companies competing in global markets, rushed and ineffective implementation of e-business in companies results in valuable resources being wasted without achieving significant tangible benefits. To minimize risks and maximize potential benefits in e-business implementation, a company needs to know to what degree it is ready for e-business and in what aspects it needs to improve itself before implementing e-business. Although a few e-readiness assessment models are used in practice, relatively little is published in academic research journals on this issue. Further, the current practical e-readiness assessment models are largely based on the experience of e-business implementation in developed countries. Given the key differences between developed and developing countries, e-business implementation in developing countries could be different from that in developed countries. This paper proposes an e-readiness assessment framework from the perspective of developing countries. The assessment framework contains five hierarchical levels, including 67 specific assessment indicators. Two field studies were conducted to illustrate and test the usability of the proposed e-readiness assessment framework in 21 retail companies of China

    Fueling recovery:The importance of energy coupling between angiogenesis and osteogenesis during fracture healing

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    Approximately half of bone fractures that do not heal properly (non-union) can be accounted to insufficient angiogenesis. The processes of angiogenesis and osteogenesis are spatiotemporally regulated in the complex process of fracture healing that requires a substantial amount of energy. It is thought that a metabolic coupling between angiogenesis and osteogenesis is essential for successful healing. However, how this coupling is achieved remains to be largely elucidated. Here, we will discuss the most recent evidence from literature pointing towards a metabolic coupling between angiogenesis and osteogenesis. We will describe the metabolic profiles of the cell types involved during fracture healing as well as secreted products in the bone microenvironment (such as lactate and nitric oxide) as possible key players in this metabolic crosstalk.</p

    Experimental method for biaxial tensile strength of fabrics and preliminary investigations

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    This paper presents a novel experimental approach to determine the biaxial strength of fabrics. A double-layer cruciform specimen was proposed based on the improvement of previous test specimen. The design and manufacture process of the novel specimen was described in detail. Uniaxial and biaxial tests of a specific material were performed subsequently. Based on numerical simulation, the biaxial strength of the fabrics was preliminary investigated. And the correlation between uniaxial and biaxial strength of the material was discussed. The proposed experiments could characterize the biaxial strength of fabrics, and the biaxial strength of the fabrics at 1:1 tension is higher than the weft strength and little lower than the warp strength

    Can surface flux transport account for the weak polar field in cycle 23?

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    To reproduce the weak magnetic field on the polar caps of the Sun observed during the declining phase of cycle 23 poses a challenge to surface flux transport models since this cycle has not been particularly weak. We use a well-calibrated model to evaluate the parameter changes required to obtain simulated polar fields and open flux that are consistent with the observations. We find that the low polar field of cycle 23 could be reproduced by an increase of the meridional flow by 55% in the last cycle. Alternatively, a decrease of the mean tilt angle of sunspot groups by 28% would also lead to a similarly low polar field, but cause a delay of the polar field reversals by 1.5 years in comparison to the observations.Comment: 9 pages, 8 figures, Space Science Reviews, accepte

    Development of a near-real-time global in situ daily precipitation dataset for 0000–0000 UTC

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    In this study, we have developed a global in situ daily precipitation dataset based on quasi-real-time sub-daily observations of precipitation totals for the 0000–0000 UTC (Co-ordinated Universal Time) day everywhere in the world. The sub-daily precipitation data from meteorological stations are obtained via the World Meteorological Organization's (WMO) Global Telecommunication System (GTS) and China Meteorological Administration Net (CMANet) archived by the National Meteorological Information Centre (NMIC) in China and the Integrated Surface Database (ISD) released by the National Centers for Environmental Information (NCEI) in the USA. We have combined these three sources into a global dataset, referred to as NMIC. Accumulated precipitation totals (depending on the country and the WMO region) are transmitted at a variety of times on the GTS. Of these, about 4,500 stations report daily for the 0000–0000 UTC day. Here, we significantly add to this, by developing two-way accumulation algorithms to decompose other reported sub-daily totals to shorter intervals, and then re-cumulate them where possible to the 0000–0000 UTC day. Using these algorithms, we increase by 51.1% of the number of stations during 2009–2016 to around 6,800 day−1. Additionally, date boundary adjustment (sliding between 1 and 6 hours either side of 0000 UTC) raises the data volume to between 7,800 and 8,700 day−1. We compare our NMIC product with the First Guess Daily (FGD) product from the Global Precipitation Climatology Centre (GPCC) and GHCN-Daily from NCEI (National Centers for Environmental Information). Root mean square differences between our NMIC and GPCC FGD products over the 2009–2016 period are around 3.4–3.7 mm·day−1 and the average consistency percentage is about 75.1–76.8%. Greater differences between NMIC and GHCN-daily are found which are probably due to the non-uniform date boundary in GHCN-Daily

    Network Cournot Competition

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    Cournot competition is a fundamental economic model that represents firms competing in a single market of a homogeneous good. Each firm tries to maximize its utility---a function of the production cost as well as market price of the product---by deciding on the amount of production. In today's dynamic and diverse economy, many firms often compete in more than one market simultaneously, i.e., each market might be shared among a subset of these firms. In this situation, a bipartite graph models the access restriction where firms are on one side, markets are on the other side, and edges demonstrate whether a firm has access to a market or not. We call this game \emph{Network Cournot Competition} (NCC). In this paper, we propose algorithms for finding pure Nash equilibria of NCC games in different situations. First, we carefully design a potential function for NCC, when the price functions for markets are linear functions of the production in that market. However, for nonlinear price functions, this approach is not feasible. We model the problem as a nonlinear complementarity problem in this case, and design a polynomial-time algorithm that finds an equilibrium of the game for strongly convex cost functions and strongly monotone revenue functions. We also explore the class of price functions that ensures strong monotonicity of the revenue function, and show it consists of a broad class of functions. Moreover, we discuss the uniqueness of equilibria in both of these cases which means our algorithms find the unique equilibria of the games. Last but not least, when the cost of production in one market is independent from the cost of production in other markets for all firms, the problem can be separated into several independent classical \emph{Cournot Oligopoly} problems. We give the first combinatorial algorithm for this widely studied problem

    Compatibility Issues With Irregular Current Injection Islanding Detection Methods in Multi-DG Units Equipped With Grid-Connected Transformers

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    Compatibility issues with irregular current injection islanding detection methods are actually the problem that some irregular currents at the same frequency injected into the same line may cancel each other out and then the islanding detection may be impaired, which have been discussed under direct couple conditions (i.e., conditions without grid-connected transformers) in the literature. This article analyzes the issues under the opposite conditions where distributed generation (DG) units are equipped with grid-connected transformers, and is aimed at finding a solution. The analysis derives the setting formulas of key parameters for both three-phase and single-phase DG units, and shows that considering fault tolerance and practicability, only specific frequencies can be used for irregular currents. The usable frequencies are different under different cases. These conclusions are different from those based on direct couple conditions. By summarizing the conclusions based on conditions with grid-connected transformers achieved in this article and those based on direct couple conditions in the literature, a complete solution to compatibility issues is obtained. The conclusions in this article have been verified by the experiments and simulations at the end of this article

    Probing theories of gravity with phase space-inferred potentials of galaxy clusters

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    Modified theories of gravity provide us with a unique opportunity to generate innovative tests of gravity. In Chameleon f(R) gravity, the gravitational potential differs from the weak-field limit of general relativity (GR) in a mass dependent way. We develop a probe of gravity which compares high mass clusters, where Chameleon effects are weak, to low mass clusters, where the effects can be strong. We utilize the escape velocity edges in the radius/velocity phase space to infer the gravitational potential profiles on scales of 0.3–1 virial radii. We show that the escape edges of low mass clusters are enhanced compared to GR, where the magnitude of the difference depends on the background field value |fR0¯¯¯¯¯|. We validate our probe using N-body simulations and simulated light cone galaxy data. For a Dark Energy Spectroscopic Instrument Bright Galaxy Sample, including observational systematics, projection effects, and cosmic variance, our test can differentiate between GR and Chameleon f(R) gravity models, |fR0¯¯¯¯¯|=4×10−6 (2×10−6) at >5σ (>2σ), more than an order of magnitude better than current cluster-scale constraints
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