检索结果-内蒙古大学图书馆

Elementary and combinatorial methods for counting prime numbers

Mathematische Semesterberichte 2017年第1期64卷 41-62页

作者： Stumpf, Pascal Institut für Mathematik Universität Würzburg Emil-Fischer-Straße 40 Würzburg 97074 Germany

Although prime numbers are elementary objects in number theory, the first non-trivial results about their distribution in history rely on analytical methods (see [10]). It was a big surprise when Erdős [5] and Selberg [12] discovered new proofs of the celebrated prime number theorem without the help of advanced tools from (complex) analysis. However, both approaches, which are not completely unrelated (see [8]), still make use of limits, in particular the real logarithm. In this article we shall introduce a rational logarithm without using any limit, and then derive classical results first due to Euler, Chebyshev and Mertens. Moreover, we revisit all necessary elementary results about prime numbers, sometimes proven in a more combinatorial fashion than usual.

关键词： Elementary combinatorial methods counting prime numbers

来源：评论

学校读者我要写书评

暂无评论

Degrobnerization: a political manifesto

引用

APPLICABLE ALGEBRA IN ENGINEERING COMMUNICATION AND COMPUTING 2022年第6期33卷 675-723页

作者： Ceria, Michela Lundqvist, Samuel Mora, Teo Politecn Bari Dipartimento Meccan Matemat & Management Via Orabona 4 I-70125 Bari Italy Stockholm Univ Dept Math S-10691 Stockholm Sweden Univ Genoa Dipartimento Matemat Via Dodecaneso 35 I-16146 Genoa Italy

Computer Algebra relies heavily on the computation of Grobner bases, and these computations are primarily performed by means of Buchberger's algorithm. In this overview paper, we focus on methods avoiding the computational intensity associated to Buchberger's algorithm and, in most cases, even avoiding the concept of Grobner bases, in favour of methods relying on linear algebra and combinatorics.

关键词： Degrobnerization Quotient algebra combinatorial methods

来源：评论

学校读者我要写书评

暂无评论

combinatorial Design of Low-Degradation Linear Arrays in Interferometric Aperture Synthesis Radiometers

引用

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2019年第12期67卷 7340-7347页

作者： Zhu, Dong Peng, Xiaohui Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China Huazhong Univ Sci & Technol Sch Elect Informat & Commun Wuhan 430074 Hubei Peoples R China Huawei Technol Co Ltd Shenzhen 518000 Guangdong Peoples R China

Radiometric sensitivity is a crucially important performance metric of interferometric aperture synthesis radiometers (IASRs). When synthesizing array geometries for optimum sensitivity performance, the minimum-degradation or low-degradation arrays (MDAs or LDAs) are employed to fulfill requirements of baseline coverage and redundancy distribution. This paper presents a study on combinatorial design of low-degradation linear arrays (LDLAs), based on a concept of multiple difference basis (MDB). Such a deterministic method can attain a satisfactory radiometric sensitivity performance in short computation time and can be easily applied in large array synthesis, compared with stochastic design methods (e.g., simulated annealing). Furthermore, the resultant LDLAs also have advantages of angular resolution and system reliability to element wreckage. Representative experiments are carried out to demonstrate the significance of the proposed MDB-based technique for designing LDLAs.

关键词： Sensitivity Geometry Redundancy Antenna arrays Radiometry Degradation combinatorial methods interferometric aperture synthesis radiometers (IASRs) low-degradation linear arrays (LDLAs) multiple difference bases (MDBs) radiometric sensitivity

来源：评论

学校读者我要写书评

暂无评论

combinatorial discovery of small molecule-doped afterglow polymer composites for anti-counterfeiting

FlexMat

引用

FlexMat 2024年

作者： Yeqing Lu Xue Chen Yung Doug Suh Xiaowang Liu Frontiers Science Center for Flexible Electronics (FSCFE) MIIT Key Laboratory of Flexible Electronics (KLoFE) Shaanxi Key Laboratory of Flexible Electronics Xi'an Key Laboratory of Flexible Electronics Xi'an Key Laboratory of Biomedical Materials & Engineering Xi'an Institute of Flexible Electronics Institute of Flexible Electronics (IFE) Xi'an Shaanxi China Northwestern Polytechnical University Xi'an Shaanxi China Department of Chemistry and School of Energy and Chemical Engineering UNIST Ulsan Republic of South Korea

The exploration of afterglow in small molecule-doped polymer composites, rooted in a nuanced understanding of structure-properties relationships, holds paramount importance for optoelectronics. However, conventional strategies face challenges in achieving high-throughput discovery of these polymers. This study introduces a novel combinatorial approach, employing photoinitiated solvent-free polymerization, to craft afterglow aromatic boronic acid-doped polymer composites. The afterglow activation results from stabilizing the triplet states of doped small molecules through a synergy of chemical and physical fixation effects. Aromatic boronic acids emerge as crucial dopants, exhibiting versatility in afterglow development across the visible spectrum. Notably, the influence of functional groups and the number of non-fused benzene rings on afterglow wavelengths is minimal, while significantly impacting afterglow lifetimes. Besides conjugation degrees, the optimal size and doping concentrations of dopants play a pivotal role in extending afterglow lifetimes. This strategy not only facilitates exploration of small molecule-based afterglow materials but also enables the feasible fabrication of intricate, multicolor afterglow polymeric objects via a step-polymerization strategy for anti-counterfeiting.

关键词： afterglow combinatorial methods doping step-polymerization triplet emission

来源：评论

学校读者我要写书评

暂无评论

Rapid Assessment of Sputtered Nanoparticle Ionic Liquid Combinations

引用

ACS combinatorial SCIENCE 2018年第4期20卷 243-250页

作者： Meyer, Hajo Meischein, Michael Ludwig, Alfred Ruhr Univ Bochum Inst Werkstoffe Werkstoffe Mikrotech Fak Maschinenbau Univ Str 150 D-44801 Bochum Germany

A high-throughput method is presented for the efficient assessment of the formation and stability of nanoparticle suspensions in ionic liquids which differ in their cations and anions. As a proof of principle, Ag was sputtered on a cavity array filled with 9 different ionic liquids. Not all nanopartide ionic liquid combinations form a stable suspension with separated nano particles. Directly after synthesis, the formation of nonagglomerated nanoparticle suspensions with sizes from 4 to 9 nm is observed by transmission electron microscopy as well as different time dependencies of the suspension stabilities. Only 3 out of the tested 9 nanopartide ionic liquid suspensions show longterm stability: Stable suspension of spherical nanopartides are formed in the ionic liquids 1-butyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide [Bmirn][(Pf)(2)N], 1-buty1-3-methylimidazoliurn bis(trifluoromethylsulfonypirnide [Binim][(Tf)(2)N], and 1-butyl-1-methylpyrrolidinum bis(trifluoromethylsulfonypimide [BinPyr][(Tf)(2)N].

关键词： silver nanoparticles ionic liquids sputter deposition combinatorial methods high-throughput characterization

来源：评论

学校读者我要写书评

暂无评论

Polyethylene glycol in spinal cord injury repair: A critical review

引用

Journal of Experimental Pharmacology 2018年 10卷 37-49页

作者： Lu, Xi Perera, T Hiran Aria, Alexander B. Callahan, Laura A Smith Department of Neurosurgery Center for Stem Cells and Regenerative Medicine University of Texas Health Science Center at Houston Houston TX United States

Polyethylene glycol (PEG) is a synthetic biocompatible polymer with many useful properties for developing therapeutics to treat spinal cord injury. Direct application of PEG as a fusogen to the injury site can repair cell membranes, mitigate oxidative stress, and promote axonal regeneration to restore motor function. PEG can be covalently or noncovalently conjugated to proteins, peptides, and nanoparticles to limit their clearance by the reticuloendothelial system, reduce their immunogenicity, and facilitate crossing the blood–brain barrier. Cross-linking PEG produces hydrogels that can act as delivery vehicles for bioactive molecules including growth factors and cells such as bone marrow stromal cells, which can modulate the inflammatory response and support neural tissue regeneration. PEG hydrogels can be cross-linked in vitro or delivered as an injectable formulation that can gel in situ at the site of injury. Chemical and mechanical properties of PEG hydrogels are tunable and must be optimized for creating the most favorable delivery environment. Peptides mimicking extracellular matrix protein such as laminin and n-cadherin can be incorporated into PEG hydrogels to promote neural differentiation and axonal extensions. Different hydrogel cross-linking densities and stiffness will also affect the differentiation process. PEG hydrogels with a gradient of peptide concentrations or Young’s modulus have been developed to systematically study these factors. This review will describe these and other recent advancements of PEG in the field of spinal cord injury in greater detail. © 2018 Lu et al.

关键词： combinatorial methods Drug delivery Fusogen Hydrogel Nanoparticles Regenerative medicine

来源：评论

学校读者我要写书评

暂无评论

Reduction in discrete optimization problem 13

Reduction in discrete optimization problem

引用

13th IEEE International Scientific and Technical Conference on Computer Sciences and Information Technologies (CSIT)

作者： Chernov, S. K. Chernova, L. S. Titov, S. D. Admiral Makarov Natl Univ Shipbldg Project Management Dept Mykolaiv Ukraine

ISBN: (纸本)9781538664650

Discrete optimization problems are used for description of models in project management. The need for solution of such problems stimulated the search for effective techniques of calculations. Currently, many combinatorial methods for solution of discrete optimization problems have been developed. Packages of computer application software have been developed for solution of standard discrete optimization problems. Yet the development of simplication algorithms for existing combinatorial techniques is appropriate since in the long run they are formally reduced to the straightforward enumeration of combinations. In case if a non-standard problem arises the method of simplication of its solution is relevant. The method of reduction for certain discrete optimization problems is suggested herein. Consideration of a model example is provided.

关键词： discrete optimization linear optimization(LO) combinatorial methods graphic method basic variables solved set objective function optimal solution

来源：评论

学校读者我要写书评

暂无评论

Reduction in discrete optimization problem

Reduction in discrete optimization problem

引用

International Scientific and Technical Conference on Computer Science and Information Technologies

作者： S. K. Chernov L. S. Chernova S. D. Titov Project Management Department Admiral Makarov National University of Shipbuilding Mykolaiv Ukraine

关键词： Discrete optimization Linear optimization(LO) combinatorial methods Graphic method Basic variables Solved set Objective function Optimal solution

来源：评论

学校读者我要写书评

暂无评论

A combinatorial lemma and its applications

引用

JOURNAL OF INEQUALITIES AND APPLICATIONS 2016年第1期2016卷 1页

作者： Mackowiak, Piotr Poznan Univ Econ Dept Math Econ Al Niepodleglosci 10 PL-61875 Poznan Poland

In this paper, we present a generalization of a combinatorial lemma we stated and proved in a recent work. Then we apply the generalized lemma to prove: (1) a theorem on the existence of a zero for an excess demand mapping, (2) the existence of a continuum of zeros for a parameterized excess demand mapping, (3) Sperner's lemma on labelings of triangulations. Proofs of these results are constructive: they contain algorithms (based on the combinatorial lemma) for the computation of objects of interest or, at least, of their approximations.

关键词： Browder fixed point theorem combinatorial methods continuum of zeros equilibrium fixed point Kakutani fixed point theorem Sperner lemma zero of a map

来源：评论

学校读者我要写书评

暂无评论

Surface chemistry gradients on silicone elastomers for high-throughput modulation of cell-adhesive interfaces

引用

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 2015年第6期103卷 2066-2076页

作者： Mohan, Greeshma Gallant, Nathan D. Univ S Florida Dept Chem & Biomed Engn Tampa FL 33620 USA Univ S Florida Dept Mech Engn Tampa FL 33620 USA

combinatorial and high-throughput approaches to screening cell responses to material properties accelerate the speed of discovery and facilitate the identification of cell instructive cues or trends that may be missed by discrete sampling. However, these technologies have not yet been widely applied to materials with tissue-like stiffness. The fabrication of monotonically varying surface chemistry gradients on polydimethylsiloxane, an elastic biomaterial, and the influence of these engineered surfaces on protein adsorption and adherent cell morphology were explored in this study. Crosslinked networks of polydimethylsiloxane were functionalized with a hydrophobic self-assembled monolayer and then modified by spatiotemporally regulated ultraviolet ozonolysis to obtain gradients of oxygenated species ranging from approximate to 10 degrees to approximate to 100 degrees in water contact angle. Automated microscopy and image analysis of fibroblast cell morphology revealed a strong correlation between cell spreading and hydrophobicity. However, structural and functional analysis of the fibronectin interface indicated a proportional increase in cell spreading with adsorption, but a biphasic relationship with fibronectin conformation, underscoring the complexity of the adhesive interface. This work demonstrates the development of an elastomer surface modification platform that can be extended to future combinatorial studies of biological responses to chemical and mechanical material properties. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2066-2076, 2015.

关键词： PDMS hydrophobicity fibronectin combinatorial methods mechanotransduction

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：