Search results for "clustered"

Hits ?▲	Authors	Title	Venue	Year	Link	Author keywords
13	Xi Shao, Changsheng Xu, Namunu Chinthaka Maddage, Qi Tian 0002, Mohan S. Kankanhalli, Jesse S. Jin	Automatic summarization of music videos.	ACM Trans. Multim. Comput. Commun. Appl.	2006	DBLP DOI BibTeX RDF	Music summarization, video summarization, music video
13	Wu Jigang, Thambipillai Srikanthan	Reconfiguration Algorithms for Power Efficient VLSI Subarrays with Four-Port Switches.	IEEE Trans. Computers	2006	DBLP DOI BibTeX RDF	Degradable VLSI array, fault tolerance, algorithms, routing, reconfiguration
13	Weiming Hu, Xuejuan Xiao, Zhouyu Fu, Dan Xie, Tieniu Tan, Stephen J. Maybank	A System for Learning Statistical Motion Patterns.	IEEE Trans. Pattern Anal. Mach. Intell.	2006	DBLP DOI BibTeX RDF	Tracking multiple objects, learning statistical motion patterns, behavior understanding, anomaly detection
13	Kien A. Hua, Ning Yu 0001, Danzhou Liu	Query Decomposition: A Multiple Neighborhood Approach to Relevance Feedback Processing in Content-based Image Retrieval.	ICDE	2006	DBLP DOI BibTeX RDF
13	Emma Hart, Hugues Bersini, Francisco C. Santos	Tolerance vs Intolerance: How Affinity Defines Topology in an Idiotypic Network.	ICARIS	2006	DBLP DOI BibTeX RDF
13	Qiankun Zhao, Tie-Yan Liu, Sourav S. Bhowmick, Wei-Ying Ma	Event detection from evolution of click-through data.	KDD	2006	DBLP DOI BibTeX RDF	dynamic web, evolution pattern, event detection, click-through data
13	Chansu Yu, Kang G. Shin, Ben Lee, Seung-Min Park 0001, Heung-Nam Kim	Node Clustering in Mobile Peer-to-Peer Multihop Networks.	PerCom Workshops	2006	DBLP DOI BibTeX RDF
13	Lin Wang 0006, Minghu Jiang, Yinghua Lu, Frank Noé, Jeremy C. Smith	Clustering Analysis of Competitive Learning Network for Molecular Data.	ISNN (1)	2006	DBLP DOI BibTeX RDF
13	Kyung-Bae Chang, Dong-Wha Kim, Gwi-Tae Park	Routing Algorithm Using GPSR and Fuzzy Membership for Wireless Sensor Networks.	ICIC (1)	2006	DBLP DOI BibTeX RDF
13	Tong Wang 0005, Daxin Liu 0001, Xuan-Zuo Lin	XML Document Clustering by Independent Component Analysis.	KDXD	2006	DBLP DOI BibTeX RDF
13	Hui Zhang 0028, Bin Pang, Ke Xie 0002, Hui Wu	An Efficient Algorithm for Clustering Search Engine Results.	CIS	2006	DBLP DOI BibTeX RDF
13	Jinlin Chen, Ping Zhong, Terry Cook	Compressing Inverted File Index Using Mixed Delta/Flat Binary Code.	ICDIM	2006	DBLP DOI BibTeX RDF
13	Jörg Sander 0001, Raymond T. Ng, Monica C. Sleumer, Man Saint Yuen, Steven J. M. Jones	A methodology for analyzing SAGE libraries for cancer profiling.	ACM Trans. Inf. Syst.	2005	DBLP DOI BibTeX RDF	cancer profiling, clustering, classification, Gene expression
13	Arnulfo P. Azcarraga, Ming-Huei Hsieh, Shan L. Pan, Rudy Setiono	Extracting salient dimensions for automatic SOM labeling.	IEEE Trans. Syst. Man Cybern. Part C	2005	DBLP DOI BibTeX RDF
13	Ozgur Turetken, Ramesh Sharda	Clustering-Based Visual Interfaces for Presentation of Web Search Results: An Empirical Investigation.	Inf. Syst. Frontiers	2005	DBLP DOI BibTeX RDF	human-computer interaction, information visualization, user study, web search, information overload
13	Pierre Salverda, Craig B. Zilles	A Criticality Analysis of Clustering in Superscalar Processors.	MICRO	2005	DBLP DOI BibTeX RDF
13	Tamer Nadeem, Ashok K. Agrawala	Performance of IEEE 802.11 based wireless sensor networks in noisy environments.	IPCCC	2005	DBLP DOI BibTeX RDF
13	Guang Jin, Silvia Nittel	UDC: A Self-adaptive Uneven Clustering Protocol for Dynamic Sensor Networks.	MSN	2005	DBLP DOI BibTeX RDF
13	DongSup Song, Sungho Kang	Increasing Embedding Probabilities of RPRPs in RIN Based BIST.	Asia-Pacific Computer Systems Architecture Conference	2005	DBLP DOI BibTeX RDF
13	Pier Francesco Cortese, Giuseppe Di Battista, Maurizio Patrignani, Maurizio Pizzonia	On Embedding a Cycle in a Plane Graph.	GD	2005	DBLP DOI BibTeX RDF
13	Stefan Bieschewski, Joan-Manuel Parcerisa, Antonio González 0001	Memory Bank Predictors.	ICCD	2005	DBLP DOI BibTeX RDF
13	François Boutin, Jérôme Thièvre, Mountaz Hascoët	Multilevel Compound Tree - Construction Visualization and Interaction.	INTERACT	2005	DBLP DOI BibTeX RDF
13	Carmelo Acosta, Ayose Falcón, Alex Ramírez, Mateo Valero	A Complexity-Effective Simultaneous Multithreading Architecture.	ICPP	2005	DBLP DOI BibTeX RDF	Complexity-Effective, Heterogeneity-Awareness, Mapping Policies, Clustering, CMP, SMT
13	Jinfeng Ni, Chinya V. Ravishankar	PA-Tree: A Parametric Indexing Scheme for Spatio-temporal Trajectories.	SSTD	2005	DBLP DOI BibTeX RDF
13	Behnam Malakooti, Ziyong Yang	Clustering and group selection of multiple criteria alternatives with application to space-based networks.	IEEE Trans. Syst. Man Cybern. Part B	2004	DBLP DOI BibTeX RDF
13	Krishna Kant 0001	A Preliminary Study of Scalability of TCP/IP Based Clusters under Database Workloads.	NETWORKING	2004	DBLP DOI BibTeX RDF
13	Alexandrin Popescul, Lyle H. Ungar	Cluster-based concept invention for statistical relational learning.	KDD	2004	DBLP DOI BibTeX RDF	clustering, relational learning, feature generation
13	Sarvesh H. Kulkarni, Ashish Srivastava, Dennis Sylvester	A new algorithm for improved VDD assignment in low power dual VDD systems.	ISLPED	2004	DBLP DOI BibTeX RDF	ECVS, dual VDD design, low power design algorithms, CVS, level converters
13	Jun Lai, Ben Soh	Using Element and Document Profile for Information Clustering.	EEE	2004	DBLP DOI BibTeX RDF	clustering, information retrieval, World Wide Web, search engine, information filtering, elements
13	Fidel Cacheda, Vassilis Plachouras, Iadh Ounis	Performance Analysis of Distributed Architectures to Index One Terabyte of Text.	ECIR	2004	DBLP DOI BibTeX RDF
13	Isabelle Corouge, Sylvain Gouttard, Guido Gerig	A Statistical Shape Model of Individual Fiber Tracts Extracted from Diffusion Tensor MRI.	MICCAI (2)	2004	DBLP DOI BibTeX RDF	statistical shape modelling, Diffusion Tensor Imaging
13	Manjunath Kudlur, Kevin Fan, Michael L. Chu, Scott A. Mahlke	Automatic Synthesis of Customized Local Memories for Multicluster Application Accelerators.	ASAP	2004	DBLP DOI BibTeX RDF
13	Amnon Shashua, Lior Wolf	Kernel Feature Selection with Side Data Using a Spectral Approach.	ECCV (3)	2004	DBLP DOI BibTeX RDF
13	Elizabeth M. Belding-Royer	Multi-Level Hierarchies for Scalable Ad hoc Routing.	Wirel. Networks	2003	DBLP DOI BibTeX RDF	hierarchial routing, ad hoc networks, scalability, mobile networking
13	Yuan Jiang 0001, Kejia Chen 0001, Zhi-Hua Zhou	SOM Based Image Segmentation.	RSFDGrC	2003	DBLP DOI BibTeX RDF
13	Michael L. Chu, Kevin Fan, Scott A. Mahlke	Region-based hierarchical operation partitioning for multicluster processors.	PLDI	2003	DBLP DOI BibTeX RDF	multicluster processor, operation partitioning, clustering, instruction-level parallelism, instruction scheduling, region-based compilation
13	Bennet Uk, Michela Taufer, Thomas Stricker, Giovanni Settanni, Andrea Cavalli, Amedeo Caflisch	Combining Task- and Data Parallelism to Speed up Protein Folding on a Desktop Grid Platform.	CCGRID	2003	DBLP DOI BibTeX RDF	data and task parallelism, CHARMM, United Devices MetaProcessor, computational grid, Protein folding, best-first search
13	Zhi-Hua Zhou, Min-Ling Zhang, Ke-Jia Chen 0001	A Novel Bag Generator for Image Database Retrieval With Multi-Instance Learning Techniques.	ICTAI	2003	DBLP DOI BibTeX RDF
13	Diego Puppin, Mark Stephenson, Saman P. Amarasinghe, Martin C. Martin, Una-May O'Reilly	Adapting Convergent Scheduling Using Machine-Learning.	LCPC	2003	DBLP DOI BibTeX RDF
13	Aurora Pons-Porrata, Rafael Berlanga Llavori, José Ruiz-Shulcloper	Building a Hierarchy of Events and Topics for Newspaper Digital Libraries.	ECIR	2003	DBLP DOI BibTeX RDF	Text Clustering, Topic Detection and Tracking
13	Kalyanmoy Deb, Manikanth Mohan, Shikhar Mishra	Towards a Quick Computation of Well-Spread Pareto-Optimal Solutions.	EMO	2003	DBLP DOI BibTeX RDF
13	Christoforos E. Kozyrakis, David A. Patterson 0001	Overcoming the Limitations of Conventional Vector Processors.	ISCA	2003	DBLP DOI BibTeX RDF
13	Hsun-Cheng Lee, Yao-Wen Chang, Jer-Ming Hsu, Hannah Honghua Yang	Multilevel floorplanning/placement for large-scale modules using B*-trees.	DAC	2003	DBLP DOI BibTeX RDF	multilevel framework, floorplanning, lagrangian relaxation
13	Guang-Ho Cha, Chin-Wan Chung	The GC-tree: a high-dimensional index structure for similarity search in image databases.	IEEE Trans. Multim.	2002	DBLP DOI BibTeX RDF
13	Walter Lee, Diego Puppin, Shane Swenson, Saman P. Amarasinghe	Convergent scheduling.	MICRO	2002	DBLP DOI BibTeX RDF
13	Dongsuk Yook	Decision Tree Based Clustering.	IDEAL	2002	DBLP DOI BibTeX RDF
13	Sung-In Jung, Hag-Young Kim, Cheolhoon Lee	Guaranteeing the Continuous Stream Service in Cluster Media Servers.	AISA	2002	DBLP DOI BibTeX RDF
13	Djordje Babic, Jussi Vesma, Tapio Saramäki, Markku Renfors	Implementation of the transposed Farrow structure.	ISCAS (4)	2002	DBLP DOI BibTeX RDF
13	Aurora Pons-Porrata, Rafael Berlanga Llavori, José Ruiz-Shulcloper	Detecting Events and Topics by Using Temporal References.	IBERAMIA	2002	DBLP DOI BibTeX RDF
13	Makan Pourzandi, Ibrahim Haddad, Charles Levert, Miroslaw Zakrzewski, Michel R. Dagenais	A New Architecture for Secure Carrier-Class Clusters.	CLUSTER	2002	DBLP DOI BibTeX RDF
13	Theodoros Evgeniou, Massimiliano Pontil	Support Vector Machines with Clustering for Training with Very Large Datasets.	SETN	2002	DBLP DOI BibTeX RDF
13	Nicolae Duta, Anil K. Jain 0001, Marie-Pierre Dubuisson-Jolly	Automatic Construction of 2D Shape Models.	IEEE Trans. Pattern Anal. Mach. Intell.	2001	DBLP DOI BibTeX RDF	flexible registration, automatic landmarks, shape clustering, Shape models, point correspondence
13	Juan C. Moure, R. B. García, Dolores Rexachs, Emilio Luque	Improving Single-Thread Fetch Performance on a Multithreaded Processor.	DSD	2001	DBLP DOI BibTeX RDF
13	Haifeng Jiang, Wenwu Lou, Wei Wang 0011	Three-Tier Clustering: An Online Citation Clustering System.	WAIM	2001	DBLP DOI BibTeX RDF
13	Sergio Luján-Mora, Manuel Palomar	Comparing String Similarity Measures for Reducing Inconsistency in Integrating Data from Different Sources.	WAIM	2001	DBLP DOI BibTeX RDF
13	Golan Yona, Michael Levitt	A unified sequence-structure classification of protein sequences: combining sequence and structure in a map of the protein space.	RECOMB	2000	DBLP DOI BibTeX RDF
13	Vladimir Y. Mariano, Rangachar Kasturi	Locating Uniform-Colored Text in Video Frames.	ICPR	2000	DBLP DOI BibTeX RDF
13	Raul Mata, Enrique Nava, Francisco Sendra	Microcalcifications Detection Using Multiresolution Methods.	ICPR	2000	DBLP DOI BibTeX RDF
13	Sung-Ho Woo, Sung-Bong Yang	An improved network clustering method for I/O-efficient query processing.	ACM-GIS	2000	DBLP DOI BibTeX RDF
13	Dimitris A. Karras, S. A. Karkanis, Dimitrios E. Maroulis	Efficient Image Compression of Medical Images Using the Wavelet Transform and Fuzzy c-means Clustering on Regions of Interest.	EUROMICRO	2000	DBLP DOI BibTeX RDF
13	Zhen He, Alonso Marquez, Stephen M. Blackburn	Opportunistic Prioritised Clustering Framework (OPCF).	Objects and Databases	2000	DBLP DOI BibTeX RDF
13	Peter R. Mattson, William J. Dally, Scott Rixner, Ujval J. Kapasi, John D. Owens	Communication Scheduling.	ASPLOS	2000	DBLP DOI BibTeX RDF
13	Yuping Yang, Mukesh Singhal	Accessing Data Cubes along Complex Dimensions.	DOLAP	1999	DBLP DOI BibTeX RDF
13	David Wai-Lok Cheung, Bo Zhou, Ben Kao, Kan Hu, Sau Dan Lee	DROLAP - A Dense-Region Based Approach to On-Line Analytical Processing.	DEXA	1999	DBLP DOI BibTeX RDF
13	Nicolas Anquetil, Timothy Lethbridge	Experiments with Clustering as a Software Remodularization Method.	WCRE	1999	DBLP DOI BibTeX RDF
13	Anssi Lensu, Pasi Koikkalainen	Similar document detection using self-organizing maps.	KES	1999	DBLP DOI BibTeX RDF
13	Silvia M. Figueira, Francine Berman	Modeling the Slowdown of Data-Parallel Applications in Homogeneous and Heterogeneous Clusters of Workstations.	Heterogeneous Computing Workshop	1998	DBLP DOI BibTeX RDF	Contention Effects, Application Slowdown, Aggregate Slowdown, Clusters of Workstations
13	Sudipto Guha, Rajeev Rastogi, Kyuseok Shim	CURE: An Efficient Clustering Algorithm for Large Databases.	SIGMOD Conference	1998	DBLP DOI BibTeX RDF
13	Bruce M. Maggs, Friedhelm Meyer auf der Heide, Berthold Vöcking, Matthias Westermann	Exploiting Locality for Data Management in Systems of Limited Bandwidth.	FOCS	1997	DBLP DOI BibTeX RDF
13	Garng M. Huang, Shan Zhu	A New HAD Algorithm for Optimal Routing of Hierarchically Structured Data Networks.	IEEE Trans. Parallel Distributed Syst.	1996	DBLP DOI BibTeX RDF	gradient projection method, hierarchically structured network, parallel processing, distributed computation, Optimal routing, data network
13	Erhard Rahm, Thomas Stöhr	Analysis of Parallel Scan Processing in Shared Disk Database Systems.	Euro-Par	1995	DBLP DOI BibTeX RDF	Disk Contention, Performance Analysis, Query Processing, Dynamic Load Balancing, Parallel Database Systems, Shared Disk
13	Takashi Matsumoto 0002, Kei Hiraki	Dynamic Switching of Coherent Cache Protocols and its Effects on Doacross Loops.	International Conference on Supercomputing	1993	DBLP DOI BibTeX RDF
13	Luiz Velho 0001, Jonas de Miranda Gomes	Digital halftoning with space filling curves.	SIGGRAPH	1991	DBLP DOI BibTeX RDF	bilevel display, quantization, space filling curves, digital halftoning, dithering
13	Chungti Liang, Wei-Tek Tsai	Multi-failure fault-tolerance of embedded loops on hypercubes: issues and performance study.	SPDP	1990	DBLP DOI BibTeX RDF
13	Hussam Y. Abujbara, Sami A. Al-Arian	Self-testing and self-reconfiguration architecture for 2-D WSI arrays.	SPDP	1990	DBLP DOI BibTeX RDF
13	Steven W. White, David C. Torney, Clive C. Whittaker	A parallel computational approach using a cluster of IBM ES/3090 600Js for physical mapping of chromosomes.	SC	1990	DBLP DOI BibTeX RDF	FORTRAN
13	T. H. Merrett	Why Sort-Merge Gives the Best Implementation of the Natural Join.	SIGMOD Rec.	1983	DBLP DOI BibTeX RDF	mutual clustering, page-pair graphs, clustering, sorting, relational algebra, merging, natural join
11	Yi Jin, Di He 0002, Shuang Wei, Wenxian Yu	Off-Grid DOA Estimation Method Based on Sparse Bayesian Learning With Clustered Structural-Aware Prior Information.	IEEE Trans. Veh. Technol.	2024	DBLP DOI BibTeX RDF
11	Kamakhya Bansal, Ashish Kumar Tripathi 0001, Avinash Chandra Pandey, Vivek Sharma	RfGanNet: An efficient rainfall prediction method for India and its clustered regions using RfGan and deep convolutional neural networks.	Expert Syst. Appl.	2024	DBLP DOI BibTeX RDF
11	Rui Zhang, Chenghui Zhang, Xiangyang Xing, Xi Liu, Frede Blaabjerg	Clustered Voltage Control and Modulation Scheme With Switching Loss Reduction for High Power Hybrid Cascaded Converter.	IEEE Trans. Ind. Electron.	2024	DBLP DOI BibTeX RDF
11	Takafumi Takatsuka, Jun Ogi, Yasuji Ikeda, Kazuki Hizu, Yutaka Inaoka, Shunsuke Sakama, Iori Watanabe, Tatsuya Ishikawa, Shohei Shimada, Junki Suzuki, Hidenori Maeda, Kenji Toshima, Yusuke Nonaka, Akifumi Yamamura, Hideki Ozawa, Fumihiko Koga, Yusuke Oike	A 3.36-μm-Pitch SPAD Photon-Counting Image Sensor Using a Clustered Multi-Cycle Clocked Recharging Technique With an Intermediate Most-Significant-Bit Readout.	IEEE J. Solid State Circuits	2024	DBLP DOI BibTeX RDF
11	Sihle Kubheka	Sampling and Forecasting Independent Data Via Clustered Bootstrap LSTM Models.	SN Comput. Sci.	2024	DBLP DOI BibTeX RDF
11	Chunhui Liang, Wenqing Ma	Heterogeneous analysis for clustered data using grouped finite mixture models.	Stat. Comput.	2024	DBLP DOI BibTeX RDF
11	Qigang Liang, Wei Wang, Xuejun Xu	A Two-Level Block Preconditioned Jacobi-Davidson Method for Multiple and Clustered Eigenvalues of Elliptic Operators.	SIAM J. Numer. Anal.	2024	DBLP DOI BibTeX RDF
11	Xianling Wang, Haijun Zhang 0001, Hongwen Yang, Yue Tian, Chen Zhu, Arumugam Nallanathan	A Non-Orthogonal Cross-Tier Joint Transmission Design for Clustered ABS-Assisted Networks.	IEEE Trans. Wirel. Commun.	2024	DBLP DOI BibTeX RDF
11	Ouyang Zhou, Junyuan Wang 0001, Fuqiang Liu, Jiangzhou Wang	Energy-Efficient Clustered Cell-Free Networking With Access Point Selection.	IEEE Open J. Commun. Soc.	2024	DBLP DOI BibTeX RDF
11	Nguyen Binh Long, Do Tuan Anh, Ha-Bang Ban, Huynh Thi Thanh Binh	A multipopulation multitasking evolutionary scheme with adaptive knowledge transfer to solve the clustered minimum routing cost tree problem.	Inf. Sci.	2024	DBLP DOI BibTeX RDF
11	Zhishang Wang, Masayuki Hisada, Abderazek Ben Abdallah	A Hybrid Clustered Approach for Enhanced Communication and Model Performance in Blockchain-Based Collaborative Learning.	IEEE Access	2024	DBLP DOI BibTeX RDF
11	Shiyi Jiang, Farshad Firouzi, Krishnendu Chakrabarty	Low-Overhead Clustered Federated Learning for Personalized Stress Monitoring.	IEEE Internet Things J.	2024	DBLP DOI BibTeX RDF
11	Zaobo He, Lintao Wang, Zhipeng Cai 0001	Clustered Federated Learning With Adaptive Local Differential Privacy on Heterogeneous IoT Data.	IEEE Internet Things J.	2024	DBLP DOI BibTeX RDF
11	Bo Xu 0020, Wenchao Xia, Haitao Zhao 0004, Yongxu Zhu, Xinghua Sun, Tony Q. S. Quek	Clustered Federated Learning in Internet of Things: Convergence Analysis and Resource Optimization.	IEEE Internet Things J.	2024	DBLP DOI BibTeX RDF
11	Yao Shan, Yu Yao, Xiaoming Zhou, Tong Zhao, Bo Hu, Lei Wang	CFL-IDS: An Effective Clustered Federated Learning Framework for Industrial Internet of Things Intrusion Detection.	IEEE Internet Things J.	2024	DBLP DOI BibTeX RDF
11	Eduardo dos Santos Teixeira, Silvio Alexandre de Araujo	Formulations for the clustered traveling salesman problem with d-relaxed priority rule.	Comput. Oper. Res.	2024	DBLP DOI BibTeX RDF
11	Thanveer Shaik 0001, Xiaohui Tao, Lin Li 0001, Niall Higgins, Raj Gururajan, Xujuan Zhou, Jianming Yong	Clustered FedStack: Intermediate Global Models with Bayesian Information Criterion.	Pattern Recognit. Lett.	2024	DBLP DOI BibTeX RDF
11	Fahad Razaque Mughal, Jingsha He, Nafei Zhu, Saqib Hussain, Zulfiqar Ali Zardari, Ghulam Ali Mallah, Md. Jalil Piran, Fayaz Ali Dharejo	Resource management in multi-heterogeneous cluster networks using intelligent intra-clustered federated learning.	Comput. Commun.	2024	DBLP DOI BibTeX RDF
11	Karl Johan Westrin, Warren Kretzschmar, Olof Emanuelsson	ClusTrast: a short read de novo transcript isoform assembler guided by clustered contigs.	BMC Bioinform.	2024	DBLP DOI BibTeX RDF
11	Tianjing Wang, ZhaoYang Dong	Blockchain-Based Clustered Federated Learning for Non-Intrusive Load Monitoring.	IEEE Trans. Smart Grid	2024	DBLP DOI BibTeX RDF
11	Haotian Sun, Shandong Wu, Xinjian Chen 0001, Ming Li, Lingji Kong, Xiaodong Yang 0005, You Meng, Shuangqing Chen, Jian Zheng 0001	SAH-NET: Structure-Aware Hierarchical Network for Clustered Microcalcification Classification in Digital Breast Tomosynthesis.	IEEE Trans. Cybern.	2024	DBLP DOI BibTeX RDF
11	Ruofei Du, Ye Jin Choi, Ji-Hyun Lee, Songthip T. Ounpraseuth, Zhuopei Hu	A weight Jackknife approach utilizing linear model based-estimators for clustered data.	Commun. Stat. Simul. Comput.	2024	DBLP DOI BibTeX RDF
11	Yuan-Hsin Lin, Li-Hsien Sun, Yi-Ju Tseng, Takeshi Emura	The Pareto type I joint frailty-copula model for clustered bivariate survival data.	Commun. Stat. Simul. Comput.	2024	DBLP DOI BibTeX RDF