期刊文献+
共找到786篇文章
< 1 2 40 >
每页显示 20 50 100
Abstraction and Representation:Form and Meaning in the Philosophy of Images
1
作者 YUAN Zhen-wei 《Journal of Literature and Art Studies》 2023年第9期716-720,共5页
This article examines the complex interplay between abstraction and representation in the ontology of images.Images inhabit an in-between space as tangible artifacts that also convey intangible ideas and meanings.The ... This article examines the complex interplay between abstraction and representation in the ontology of images.Images inhabit an in-between space as tangible artifacts that also convey intangible ideas and meanings.The analysis synthesizes perspectives from across the history of philosophy to elucidate how images bridge abstraction and representation through their form and function.It engages with ongoing epistemological and aesthetic debates concerning the dual nature of images.Plato’s theory of ideal forms is outlined as an early attempt to define abstraction.Modern semiotic theories are discussed for their insights into how images create meaning through codes and signs.Phenomenology offers an alternative approach by prioritizing the sensorial,affective impact of images.Poststructuralism problematizes representation in the context of mechanical reproduction and simulacra.While diverse,these philosophical frameworks all grapple with the issues images pose between abstract essence and concrete appearance,conceptual ideas and sensory manifestations.The article reveals the richness of images as liminal constructs that collapse dualisms in their creative interfacing of material forms and immaterial meanings.It concludes that this ontological ambiguity empowers images as mediators between imagination and perception,subjectivity and reality. 展开更多
关键词 abstraction IMAGES SEMIOTICS DUALISM PLATO
下载PDF
Theoretical Study on the Excited-state Intramolecular Hydrogen Abstraction Reactions of Butanal 被引量:1
2
作者 吕玲玲 杨声 +2 位作者 袁琨 王小芳 王永成 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第10期1226-1235,共10页
The excited-state intramolecular hydrogen abstraction reactions of butanal have been investigated using the CAS-MP2/6-311+G^*//CASSCF/6-31G^* methods. Calculated results show that the hydrogen transfer induced fluo... The excited-state intramolecular hydrogen abstraction reactions of butanal have been investigated using the CAS-MP2/6-311+G^*//CASSCF/6-31G^* methods. Calculated results show that the hydrogen transfer induced fluorescence quenching of the n,π^*-excited state of covalent butanal with three paths: (1) The first path corresponds to direct S0-react reconstitution, which involves the first S1 decay by partial hydrogen atom transfer. (2) The second stepwise mechanism can be viewed as a full hydrogen atom transfer followed by a partial hydrogen atom back transfer, electron transfer (near S1/S0 or S0-TS) and finally a proton transfer to S0-react. (3) On the triplet surface, the surface crossing to the singlet state would be clearly much efficient at the T1/S0 region due to the large SOC value of 8.3 cm^-1. The S0-react decay route from T1/S0 was studied with an intrinsic reaction coordinate (IRC) calculation at the CASSCF level, resulting in the S0-React minimum. 展开更多
关键词 butanal valence bond theory (VB) state correlation diagram hydrogen abstraction mechanism
下载PDF
Topology Abstraction Service for IP VPNs: Core Network Partitioning for Resource Sharing 被引量:1
3
作者 Ravishankar Ravindran Changcheng Huang +1 位作者 Krishnaiyan Thulasiraman Tachun Lin 《American Journal of Operations Research》 2018年第3期167-202,共36页
VPN service providers (VSP) and IP-VPN customers have traditionally maintained service demarcation boundaries between their routing and signaling entities. This has resulted in the VPNs viewing the VSP network as an o... VPN service providers (VSP) and IP-VPN customers have traditionally maintained service demarcation boundaries between their routing and signaling entities. This has resulted in the VPNs viewing the VSP network as an opaque entity and therefore limiting any meaningful interaction between the VSP and the VPNs. A key challenge is to expose each VPN to information about available network resources through an abstraction (TA) [1] which is both accurate and fair. In [2] we proposed three decentralized schemes assuming that all the border nodes performing the abstraction have access to the entire core network topology. This assumption likely leads to over- or under-subscription. In this paper we develop centralized schemes to partition the core network capacities, and assign each partition to a specific VPN for applying the decentralized abstraction schemes presented in [2]. First, we present two schemes based on the maximum concurrent flow and the maximum multicommodity flow (MMCF) formulations. We then propose approaches to address the fairness concerns that arise when MMCF formulation is used. We present results based on extensive simulations on several topologies, and provide a comparative evaluation of the different schemes in terms of abstraction efficiency, fairness to VPNs and call performance characteristics achieved. 展开更多
关键词 IP-VPN SERVICE TOPOLOGY abstraction MAXIMUM Concurrent FLOW MAXIMUM MULTICOMMODITY FLOW
下载PDF
Vibration Feature Abstraction and Classification of Diesel Fault 被引量:1
4
作者 ZHANG Xi ning, WEN Guang rui, LI Xin yi College of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, P.R.China Abstract: The feature of a periodic cyclic nonstationary signal for a cyclic working machine such as a diesel engine is studied in the aspect of working procedure, force and vibration. On the basis of the study, a method of characteristic 《International Journal of Plant Engineering and Management》 2003年第1期35-40,共6页
ion and classification is put forward for periodic cyclic nonstationary vibration signal. The proposed method is applied to experimental data of an ISUZU C240 diesel engine. Experiment results show the effectiveness ... ion and classification is put forward for periodic cyclic nonstationary vibration signal. The proposed method is applied to experimental data of an ISUZU C240 diesel engine. Experiment results show the effectiveness of the proposed method in classification of engine faults. 展开更多
关键词 diesel engine periodic cyclic nonstationary signal feature abstraction principal component analysis
下载PDF
Abstraction from Constructors and Functional Constructors and Their Applications
5
作者 Kazuhiko Kakehi 1, Robert Gluck 2, Yoshihiko Futamura 3 1 JSPS Research Fellow Graduate School of Science and Engineering, Waseda University,Tokyo 169 8555, Japan 2 PRESTO, JST & Institute for Software Production Technology, Waseda Universi 《Wuhan University Journal of Natural Sciences》 CAS 2001年第Z1期368-374,共7页
Structures using constructors are of ordinary use in functional programming to represent data structures of unbound size. Lack of associativity of constructors, however, hinders program analyses or efficient execution... Structures using constructors are of ordinary use in functional programming to represent data structures of unbound size. Lack of associativity of constructors, however, hinders program analyses or efficient executions. This paper describes ideas of abstraction toward constructors, and similarly abstraction from constructing functions, which we call functional constructors. We demonstrate our ideas making program analyses easier and enable transformation to efficient execution. 展开更多
关键词 program transformation lambda abstraction CONSTRUCTORS recursion removal tupling
下载PDF
Automatic abstraction of interference fringes with image technique
6
作者 浦昭邦 陶卫 张敏 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2002年第2期166-169,共4页
ion technique of interference fringes used in phase modulation and phase scanning modulation interferometer is presented. For the measurement of amplitudes of interference fringes, fringes are fitted and their central... ion technique of interference fringes used in phase modulation and phase scanning modulation interferometer is presented. For the measurement of amplitudes of interference fringes, fringes are fitted and their central points are determined automatically according to their distribution rules. However, for the measurement of their phases, fringes should be recognized and processed with different calculating algorithms and least square optimization methods depending on the scanning modulation mode. When this technique is used for measurement of surface roughness, the measurement uncertainty is better than 5nm and the repeatability is less than 5%. 展开更多
关键词 INTERFERENCE FRINGES abstraction PHASE-MODULATION IMAGE detection
下载PDF
The CH_3OH+Cl Hydrogen Abstraction Reactions: An ab initio Study
7
作者 Bo Zhen CHEN Ming Bao HUANG 《Chinese Chemical Letters》 SCIE CAS CSCD 2001年第8期727-730,共4页
The two channels of the CH(3)OH+Cl hydrogen abstraction reaction, leading to the final products CH(2)OH+HCl (i) and CH(3)O+HCl (ii), have been studied by performing ab initio MP2 calculations with the triplet split-va... The two channels of the CH(3)OH+Cl hydrogen abstraction reaction, leading to the final products CH(2)OH+HCl (i) and CH(3)O+HCl (ii), have been studied by performing ab initio MP2 calculations with the triplet split-valence polarization basis sets. For each of the two channels the following simple reaction path is predicted: reactants --> transition state --> intermediate --> products. The previously reported complicated paths(2) calculated without using the IRC technique are criticized. Our calculations indicate that channel (i) is exothermic and has a negligible energy barrier while channel (ii) is endothermic and has a substantial energy barrier. These results imply that channel (i) is favorable, which is in line with experiment. 展开更多
关键词 abstraction reaction ab initio calculation IRC
下载PDF
Deadlock detection using abstraction refinement
8
作者 曾红卫 《Journal of Shanghai University(English Edition)》 2010年第1期1-5,共5页
This paper adopts counterexample guided abstraction refinement scheme to alleviate the state explosion problem of deadlock detection. We extend the classical labeled transition system models by qualifying transitions ... This paper adopts counterexample guided abstraction refinement scheme to alleviate the state explosion problem of deadlock detection. We extend the classical labeled transition system models by qualifying transitions as certain and uncertain to make deadlock-freedom conservative, i.e. if the abstraction of a system is deadlock-free, then the system is deadlock-free. An abstraction refinement approach to deadlock detection is proposed, and the correctness of the approach is proved. 展开更多
关键词 deadlock detection state explosion extended labeled transition system abstraction refinement COUNTEREXAMPLE
下载PDF
Modeling Abstraction Hierarchy Levels of the Cyber Attacks Using Random Process
9
作者 Gilles Durrieu Emmanuel Frenod +1 位作者 Thierry Morineau Thong Quoc Nguyen 《Open Journal of Statistics》 2017年第3期500-520,共21页
Aspects of human behavior in cyber security allow more natural security to the user. This research focuses the appearance of anticipating cyber threats and their abstraction hierarchy levels on the mental picture leve... Aspects of human behavior in cyber security allow more natural security to the user. This research focuses the appearance of anticipating cyber threats and their abstraction hierarchy levels on the mental picture levels of human. The study concerns the modeling of the behaviors of mental states of an individual under cyber attacks. The mental state of agents being not observable, we propose a non-stationary hidden Markov chain approach to model the agent mental behaviors. A renewal process based on a nonparametric estimation is also considered to investigate the spending time in a given mental state. In these approaches, the effects of the complexity of the cyber attacks are taken into account in the models. 展开更多
关键词 CYBER ATTACKS abstraction HIERARCHY Hidden Markov Chain NONPARAMETRIC Estimation RENEWAL Process
下载PDF
Density Functional Theory Studies on the Addition and Abstraction Reactions of OH Radical with Benzoate Anion
10
作者 Nobuaki Tanaka Shigeo Itoh 《Open Journal of Physical Chemistry》 2013年第1期7-13,共7页
The addition and abstraction reactions of OH radical with benzoate anion are investigated by density functional theory calculations that include solvent effects using UB3LYP, UCAM-B3LYP, UmPW1PW91 and UM06-2X function... The addition and abstraction reactions of OH radical with benzoate anion are investigated by density functional theory calculations that include solvent effects using UB3LYP, UCAM-B3LYP, UmPW1PW91 and UM06-2X functionals with the 6-311++G(2d,2p) basis set. Geometry optimizations of the reactants, products and transition state species are performed for the possible reaction paths. For the addition reactions, those targeting the ipso-, ortho-, meta- and para-carbons are predicted to be exoergic. The H-atom abstraction reactions from ortho, meta and para positions are also predicted to be exoergic. On the basis of the rate constants calculated by means of the transition state theory, the H-atom abstraction reaction from the ortho position is determined to be the favored path followed by the ortho OH addition reaction. 展开更多
关键词 DFT Calculation BENZOATE ANION H-ATOM abstraction OH ADDITION Transition State Theory
下载PDF
Real-time flow-based video abstraction using OpenCL
11
作者 Yong-jin PARK Jin-woo KIM +1 位作者 Jin-hong PARK Tack-don HAN 《Journal of Measurement Science and Instrumentation》 CAS 2012年第1期46-50,共5页
A non-photorealistic rendering technique is a method to show various effects different from those of realistic image generation.Of the various techniques,flow-based image abstraction displays the shape and color featu... A non-photorealistic rendering technique is a method to show various effects different from those of realistic image generation.Of the various techniques,flow-based image abstraction displays the shape and color features well and performs a stylistic visual abstraction.But real-time rendering is impossible when CPU is used because it applies various filtering and iteration methods.In this paper,we present real-time processing methods of video abstraction using open open computing language(OpenCL),technique of general-purpose computing on graphics processing units(GPGPU).Through the acceleration of general-purpose computing(GPU),16 frame-per-second(FPS)or greater is shown to process video abstraction. 展开更多
关键词 non-photorealistic rendering video abstraction general-purpose computing on graphics processing units(GPGPU) open computing language(OpenCL)
下载PDF
Multiple Levels of Abstraction in the Simulation of Microthreaded Many-Core Architectures
12
作者 Irfan Uddin 《Open Journal of Modelling and Simulation》 2015年第4期159-190,共32页
Simulators are generally used during the design of computer architectures. Typically, different simulators with different levels of complexity, speed and accuracy are used. However, for early design space exploration,... Simulators are generally used during the design of computer architectures. Typically, different simulators with different levels of complexity, speed and accuracy are used. However, for early design space exploration, simulators with less complexity, high simulation speed and reasonable accuracy are desired. It is also required that these simulators have a short development time and that changes in the design require less effort in the implementation in order to perform experiments and see the effects of changes in the design. These simulators are termed high-level simulators in the context of computer architecture. In this paper, we present multiple levels of abstractions in a high-level simulation of a general-purpose many-core system, where the objective of every level is to improve the accuracy in simulation without significantly affecting the complexity and simulation speed. 展开更多
关键词 HIGH-LEVEL Simulations MULTIPLE LEVELS of abstraction Design Space Exploration MANY-CORE Systems
下载PDF
Internal Water Flows and Particles Abstraction in Daphnia
13
作者 Moshe Gophen 《Open Journal of Ecology》 2022年第11期742-755,共14页
The operational function of the trunk limbs (thoracic appendages), of Daphnia, P3 and P4, is a long-term disputed definition between “solid walls”, sieving filters. Sieving is unlikely process for routine particle c... The operational function of the trunk limbs (thoracic appendages), of Daphnia, P3 and P4, is a long-term disputed definition between “solid walls”, sieving filters. Sieving is unlikely process for routine particle collection, particle capture is not a simple mechanical process and not by sieving alone. Analysis promotion supported by direct observational examination of the in-vivo cinematographic slow-motion film and magnified solid photos of tethered Daphnia by high-speed camera (250 frames per second) resulted in a definite interpretation presented in this paper. The Daphnia’s feeding mechanism achieves particles abstraction not by sieving. The existence of two internal alternate water flow routs was indicated: Lateral and Median. These micro flow structures are suggested as vulnerability reduction. 展开更多
关键词 DAPHNIA Particle abstraction Solid Walls Internal Flow Rout
下载PDF
Visual abstraction of dynamic network via improved multi-class blue noise sampling
14
作者 Yanni PENG Xiaoping FAN +5 位作者 Rong CHEN Ziyao YU Shi LIU Yunpeng CHEN Ying ZHAO Fangfang ZHOU 《Frontiers of Computer Science》 SCIE EI CSCD 2023年第1期171-185,共15页
Massive sequence view (MSV) is a classic timeline-based dynamic network visualization approach. However, it is vulnerable to visual clutter caused by overlapping edges, thereby leading to unexpected misunderstanding o... Massive sequence view (MSV) is a classic timeline-based dynamic network visualization approach. However, it is vulnerable to visual clutter caused by overlapping edges, thereby leading to unexpected misunderstanding of time-varying trends of network communications. This study presents a new edge sampling algorithm called edge-based multi-class blue noise (E-MCBN) to reduce visual clutter in MSV. Our main idea is inspired by the multi-class blue noise (MCBN) sampling algorithm, commonly used in multi-class scatterplot decluttering. First, we take a node pair as an edge class, which can be regarded as an analogy to classes in multi-class scatterplots. Second, we propose two indicators, namely, class overlap and inter-class conflict degrees, to measure the overlapping degree and mutual exclusion, respectively, between edge classes. These indicators help construct the foundation of migrating the MCBN sampling from multi-class scatterplots to dynamic network samplings. Finally, we propose three strategies to accelerate MCBN sampling and a partitioning strategy to preserve local high-density edges in the MSV. The result shows that our approach can effectively reduce visual clutters and improve the readability of MSV. Moreover, our approach can also overcome the disadvantages of the MCBN sampling (i.e., long-running and failure to preserve local high-density communication areas in MSV). This study is the first that introduces MCBN sampling into a dynamic network sampling. 展开更多
关键词 dynamic network visualization massive sequence view multi-class blue noise sampling visual abstraction
原文传递
Unified Enclave Abstraction and Secure Enclave Migration on Heterogeneous Security Architectures 被引量:2
15
作者 古金宇 李浩 +3 位作者 夏虞斌 陈海波 秦承刚 何征宇 《Journal of Computer Science & Technology》 SCIE EI CSCD 2022年第2期468-486,共19页
Nowadays,application migration becomes more and more attractive.For example,it can make computation closer to data sources or make service closer to end-users,which may significantly decrease latency in edge computing... Nowadays,application migration becomes more and more attractive.For example,it can make computation closer to data sources or make service closer to end-users,which may significantly decrease latency in edge computing.Yet,migrating applications among servers that are controlled by different platform owners raises security issues.We leverage hardware-secured trusted execution environment(TEE,aka.,enclave)technologies,such as Intel SGX,AMD SEV,and ARM TrustZone,for protecting critical computations on untrusted servers.However,these hardware TEEs propose non-uniform programming abstractions and are based on heterogeneous architectures,which not only forces programmers to develop secure applications targeting some specific abstraction but also hinders the migration of protected applications.Therefore,we propose UniTEE which gives a unified enclave programming abstraction across the above three hardware TEEs by using a microkernel-based design and enables the secure enclave migration by integrating heterogeneous migration techniques.We have implemented the prototype on real machines.The evaluation results show the migration support incurs nearly-zero runtime overhead and the migration procedure is also efficient. 展开更多
关键词 heterogeneous trusted execution environment(TEE) enclave abstraction enclave migration
原文传递
Quantum chemical study on insertion and abstraction reaction of dichlorocarbene with methyl alcohol and methyl mercaptan 被引量:1
16
作者 LI ZhiFeng ZHU YuanCheng +2 位作者 LI HuiXue LIU XinWen LU XiaoQuan 《Science China Chemistry》 SCIE EI CAS 2009年第3期304-312,共9页
The insertion and abstraction reaction mechanisms of singlet and triplet CCl2 with CH3MH (M=O, S) have been studied by using the DFT, NBO and AIM methods. The geometries of reactions, the transition state and products... The insertion and abstraction reaction mechanisms of singlet and triplet CCl2 with CH3MH (M=O, S) have been studied by using the DFT, NBO and AIM methods. The geometries of reactions, the transition state and products were completely optimized by B3LYP/6-311G(d, p). All the energy of the species was obtained at the CCSD(T)/6-311G(d, p) level. The calculated results indicated that the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CCl2 can not only trigger the insertion reaction with C-H and M-H in four pathways, by which the products P1 [CH3OCHCl2, reactionⅠ(1)], P3[Cl2HCCH2OH, reactionⅠ(2)], P5[CH3SCHCl2, reactionⅡ(1)] and P7[Cl2HCCH2SH, reac-tion Ⅱ(2)] are produced respectively, but also abstract M-H, resulting P4 [CH2O+CH2Cl2, reactionⅠ(3)] and P8[CH2S+CH2Cl2, reactionⅡ(3)]. In addition, the important geometries in domain pathways have been studied by AIM and NBO theories. 展开更多
关键词 CARBENE alcohol DFT NBO AIM INSERTION REACTION abstraction REACTION
原文传递
Combining search space partition and abstraction for LTL model checking 被引量:2
17
作者 PU Fei ZHANG WenHui 《Science in China(Series F)》 2007年第6期793-810,共18页
关键词 search space partition REFINEMENT abstraction LTL model checking
原文传递
Abstraction for model checking multi-agent systems 被引量:1
18
作者 Conghua Zhou (1) chzhou@ujs.edu.cn Bo Sun (1) Zhifeng Liu (1) 《Frontiers of Computer Science》 SCIE EI CSCD 2011年第1期14-25,共12页
Model checking multi-agent systems (MAS) always suffers from the state explosion problem. In this paper we focus on an abstraction technique which is one of the major methods for overcoming this problem. For a multi... Model checking multi-agent systems (MAS) always suffers from the state explosion problem. In this paper we focus on an abstraction technique which is one of the major methods for overcoming this problem. For a multi-agent system, we present a novel abstraction procedure which reduces the state space by collapsing the global states in the system. The abstraction is automatically computed according to the property to be verified. The resulting abstract system simulates the concrete system, while the universal temporal epistemic properties are preserved. Our abstraction is an over-approximation. If some universal temporal epistemic property is not satisfied, then we need to identify spurious counterexamples. We further show how to reduce complex counterexamples to simple structures, i.e., paths and loops, such that the counterexamples can be checked and the abstraction can be refined efficiently. Finally, we illustrate the abstraction technique with a card game. 展开更多
关键词 model checking abstraction refinement epistemic temporal logic
原文传递
欢迎订阅《食品工业》
19
《工业微生物》 CAS 2024年第2期175-175,共1页
《食品工业》杂志创刊于1979年,是一份专门从事研究食品科技的综合性科技期刊。是《中国学术期刊网络出版总库》和美国《CHEMICAL ABSTRACTS》收录期刊。《食品工业》在国内外公开发行,邮发代号:4-503,全国各地邮局均可订阅。国内统一... 《食品工业》杂志创刊于1979年,是一份专门从事研究食品科技的综合性科技期刊。是《中国学术期刊网络出版总库》和美国《CHEMICAL ABSTRACTS》收录期刊。《食品工业》在国内外公开发行,邮发代号:4-503,全国各地邮局均可订阅。国内统一连续出版物号:CN 31-1532/TS。 展开更多
关键词 综合性科技期刊 食品科技 邮发代号 中国学术期刊网络出版总库 杂志创刊 订阅 ABSTRACTS 食品工业
下载PDF
Reduction and Simplification of Explicit LTL Model Checking via an Abstraction Method
20
作者 孙军波 罗贵明 《Tsinghua Science and Technology》 SCIE EI CAS 2009年第1期90-94,共5页
An abstraction method developed for the explicit linear temporal logic model checking was geared towards reducing the useless part of the state space during the abstraction period. This reduces the cost during the abs... An abstraction method developed for the explicit linear temporal logic model checking was geared towards reducing the useless part of the state space during the abstraction period. This reduces the cost during the abstraction period relative to models requiring many useless states. A dining-philosophers example comparing this abstraction method with conventional methods indicates that a large proportion of the state space has been reduced by this abstraction method. Finally, the abstract method is shown to be correct and an analysis is given to show how such a large proportion of states can be reduced. 展开更多
关键词 linear temporal logic explicit model checking abstraction Buchi automaton
原文传递
上一页 1 2 40 下一页 到第
使用帮助 返回顶部