Search results for "recoverable"

Hits ?▲	Authors	Title	Venue	Year	Link	Author keywords
92	Jörg Kienzle, Alfred Strohmeier	Shared Recoverable Objects.	Ada-Europe	1999	DBLP DOI BibTeX RDF	Recoverable Objects, Controlled Types, Abort Deferred Regions, Concurrency, Object-Oriented Programming, Transactions, Software Fault Tolerance, Ada 95
82	Serafino Cicerone, Gianlorenzo D'Angelo, Gabriele Di Stefano, Daniele Frigioni, Alfredo Navarra, Michael Schachtebeck, Anita Schöbel	Recoverable Robustness in Shunting and Timetabling.	Robust and Online Large-Scale Optimization	2009	DBLP DOI BibTeX RDF
66	Bing Su, Yinfeng Xu, Peng Xiao, Lei Tian	A Risk-Reward Competitive Analysis for the Recoverable Canadian Traveller Problem.	COCOA	2008	DBLP DOI BibTeX RDF	Recoverable-CTP, Comparison strategy, Risk-reward model, Competitive analysis
66	Adam L. Young, Moti Yung	Auto-Recoverable Cryptosystems with Faster Initialization and the Escrow Hierarchy.	Public Key Cryptography	1999	DBLP DOI BibTeX RDF	Auto-Recoverable Auto-Certifiable Cryptosystems, NIZK, software key escrow, escrow hierarchy, RSA, Public Key, Key Escrow, ElGamal
66	Célio Estevan Morón	Designing a real-time recoverable action.	RTCSA	1996	DBLP DOI BibTeX RDF	real-time recoverable action, reliability requirements, fault-tolerance requirements, reliable real-time systems, forward error recovery, real-time systems, real-time constraints, adaptable scheduler, backward error recovery
62	Peter Kalocsai	Biologically Inspired Recognition Model with Extension Fields.	ICIP (2)	1997	DBLP DOI BibTeX RDF	biologically inspired recognition model, shape similarity measure, multiorientation Gabor filter, multiscale Gabor filter, human object recognition, complementary feature-deleted images, nonrecoverable contour-deleted image, recoverable contour-deleted image, connectivity pattern, collinear units, curvilinear units, human psychophysical results, noisy input image processing, image recognition, recognition rate, primary visual cortex, recognition performance
56	Vladimir Nikolov, Rüdiger Kapitza, Franz J. Hauck	Recoverable Class Loaders for a Fast Restart of Java Applications.	Mob. Networks Appl.	2009	DBLP DOI BibTeX RDF	Java, OSGi, snapshot, overhead, start-up
56	Christian Liebchen, Marco E. Lübbecke, Rolf H. Möhring, Sebastian Stiller	The Concept of Recoverable Robustness, Linear Programming Recovery, and Railway Applications.	Robust and Online Large-Scale Optimization	2009	DBLP DOI BibTeX RDF
53	Joseph K. Liu, Patrick P. Tsang, Duncan S. Wong	Recoverable and Untraceable E-Cash.	EuroPKI	2005	DBLP DOI BibTeX RDF	Untraceable, E-Cash, Recoverable
53	Marcel-Catalin Rosu, Karsten Schwan	Support for Recoverable Memory in the Distributed Virtual Communication Machine.	IPDPS	2000	DBLP DOI BibTeX RDF	recoverable memory, virtual machine, extensibility, communication architecture
52	Youngsoo Choi, Sanguk Noh, Kyunghee Choi, Gihyun Jung	Autonomous and Dependable Recovery Scheme in UPnP Network Settings.	IDEAL	2005	DBLP DOI BibTeX RDF
49	Adam L. Young, Moti Yung	Finding Length-3 Positive Cunningham Chains.	ANTS	1998	DBLP DOI BibTeX RDF	Cunningham Chains, Auto-Recoverable and Auto-Certifiable Cryptosystem, ElGamal system, Public-Key Cryptosystems, Primality testing
49	Jeannette M. Wing	Using Larch to Specify Avalon/C++ Objects.	IEEE Trans. Software Eng.	1990	DBLP DOI BibTeX RDF	Avalon/C++ objects, subatomic, nonfunctional properties, complex properties, formal specification, formal specification, atomic, recoverable, Larch
43	Tomoaki Yoshikai, Marika Hayashi, Asuka Kadowaki, Takefumi Goto, Masayuki Inaba	Design and development of a humanoid with Soft 3D-deformable sensor flesh and automatic recoverable mechanical overload protection mechanism.	IROS	2009	DBLP DOI BibTeX RDF
43	Guangzhen Li, Yoshimichi Ito, Xiaoyi Yu, Naoko Nitta, Noboru Babaguchi	A discrete wavelet transform based recoverable image processing for privacy protection.	ICIP	2008	DBLP DOI BibTeX RDF
43	Vladimir Nikolov, Rüdiger Kapitza	Recoverable class loaders for a fast restart of Java applications.	MOBILWARE	2008	DBLP DOI BibTeX RDF
43	Kuo-Lung Hung, Chin-Chen Chang 0001	Recoverable Tamper Proofing Technique for Image Authentication Using Irregular Sampling Coding.	ATC	2007	DBLP DOI BibTeX RDF
43	Adam L. Young, Moti Yung	Auto-recoverable Auto-certifiable Cryptosystems (A Survey).	CQRE	1999	DBLP DOI BibTeX RDF
43	Mahadev Satyanarayanan, Henry H. Mashburn, Puneet Kumar 0001, David C. Steere, James J. Kistler	Lightweight Recoverable Virtual Memory.	ACM Trans. Comput. Syst.	1994	DBLP DOI BibTeX RDF	Camelot, RVM, scalability, throughput, Unix, persistence, paging, logging, truncation, Coda
43	Mahadev Satyanarayanan, Henry H. Mashburn, Puneet Kumar 0001, David C. Steere, James J. Kistler	Lightweight Recoverable Virtual Memory.	SOSP	1993	DBLP DOI BibTeX RDF	UNIX
43	C. V. Ramamoorthy, Yuh Yaw, R. Aggarwal, J. Song	Synthesis of two-party error-recoverable protocols.	SIGCOMM	1986	DBLP DOI BibTeX RDF
40	Peter Bodorik, Dawn N. Jutla, A. Agarwal	Recoverable Virtual Memory through the Multi-View Memory Computer System.	HICSS	1999	DBLP DOI BibTeX RDF	Recoverable Virtual Memory, Multi-view Virtual Memory, Protection Architecture, Architectural Support for Operating Systems, Access Control
39	Ailixier Aikebaier, Tomoya Enokido, Makoto Takizawa 0001	A Backward Algorithm in a Distributed Agreement Computing.	ICPADS	2008	DBLP DOI BibTeX RDF
39	David B. Lomet, Mark R. Tuttle	Logical Logging to Extend Recovery to New Domains.	SIGMOD Conference	1999	DBLP DOI BibTeX RDF
39	Peter Kalocsai	Recognition Model with Extension Fields.	IWANN	1997	DBLP DOI BibTeX RDF
36	Charles P. Wright, Richard P. Spillane, Gopalan Sivathanu, Erez Zadok	Extending ACID semantics to the file system.	ACM Trans. Storage	2007	DBLP DOI BibTeX RDF	File system transactions, ptrace monitors, recoverable memory, databases, file systems
36	Mohsen Sharifi, S. F. Noorani, F. Orooji	A New Technique for Participation of Non-CORBA Independent Persistent Objects in OTS Transactions.	EurAsia-ICT	2002	DBLP DOI BibTeX RDF	Object Transaction Service (OTS), Recoverable Object, Shadow Object, CORBA, Distributed Transaction, Persistent Object
36	Jung-Ho Ahn 0001, Kang-Woo Lee, Hyoung-Joo Kim 0001	Architectural Issues in Adopting Distributed Shared Memory for Distributed Object Management Systems.	FTDCS	1995	DBLP DOI BibTeX RDF	object management system, recoverable virtual memory, distributed shared memory, buffer management, false sharing
33	Balaji Srinivasan Babu, P. Vijay Kumar	On Partial Maximally-Recoverable and Maximally-Recoverable Codes.	CoRR	2015	DBLP BibTeX RDF
33	Balaji Srinivasan Babu, P. Vijay Kumar	On partial maximally-recoverable and maximally-recoverable codes.	ISIT	2015	DBLP DOI BibTeX RDF
33	Xu Wang 0005, Ali Saberi, Anton A. Stoorvogel, Sandip Roy 0002, Peddapullaiah Sannuti	Computation of the recoverable region and stabilisation problem in the recoverable region for discrete-time systems.	Int. J. Control	2009	DBLP DOI BibTeX RDF
33	Daniel Marco	Markov Random Processes are not Recoverable After Quantization and Mostly not Recoverable From Samples.	ISIT	2007	DBLP DOI BibTeX RDF
33	Anton A. Stoorvogel, Ali Saberi, Guoyong Shi	Properties of recoverable region and semi-global stabilization in recoverable region for linear systems subject to constraints.	Autom.	2004	DBLP DOI BibTeX RDF
33	Anton A. Stoorvogel, Ali Saberi, Guoyong Shi	Properties of recoverable region and semi-global stabilization in recoverable region for linear systems subject to constraints.	ACC	2003	DBLP DOI BibTeX RDF
30	Gianlorenzo D'Angelo, Gabriele Di Stefano, Alfredo Navarra, Maria Cristina Pinotti	Recoverable Robust Timetables on Trees.	COCOA	2009	DBLP DOI BibTeX RDF
30	Aleksandra Nenadic, Ning Zhang 0001, Qi Shi 0001, Carole A. Goble	DSA-Based Verifiable and Recoverable Encryption of Signatures and Its Application in Certified E-Goods Delivery.	EEE	2005	DBLP DOI BibTeX RDF
30	Ming Yao, Kun Peng, Matthew Henricksen, Ernest Foo, Ed Dawson	Using Recoverable Key Commitment to Defend Against Truncation Attacks in Mobile Agents.	EC-Web	2004	DBLP DOI BibTeX RDF
30	Misha Dmitriev 0001, Craig Hamilton	Towards Scalable and Recoverable Object Evolution for the PJama Persistent Platform.	Objects and Databases	2000	DBLP DOI BibTeX RDF
30	Douglas M. Blough, Fadi J. Kurdahi, Seong Yong Ohm	High-level synthesis of recoverable VLSI microarchitectures.	IEEE Trans. Very Large Scale Integr. Syst.	1999	DBLP DOI BibTeX RDF
30	Adam L. Young, Moti Yung	Auto-Recoverable Auto-Certifiable Cryptosystems.	EUROCRYPT	1998	DBLP DOI BibTeX RDF
30	Douglas M. Blough, Fadi J. Kurdahi, Seong Yong Ohm	Optimal algorithms for recovery point insertion in recoverable microarchitectures.	IEEE Trans. Comput. Aided Des. Integr. Circuits Syst.	1997	DBLP DOI BibTeX RDF
30	Philip A. Bernstein, Meichun Hsu, Bruce Mann	Implementing Recoverable Requests Using Queues.	SIGMOD Conference	1990	DBLP DOI BibTeX RDF
26	Frank McCown, Michael L. Nelson	Recovering a website's server components from the web infrastructure.	JCDL	2008	DBLP DOI BibTeX RDF	search engine caches, web server, digital preservation, web archiving, backup
26	Cheng Huang 0002, Minghua Chen 0001, Jin Li 0001	Pyramid Codes: Flexible Schemes to Trade Space for Access Efficiency in Reliable Data Storage Systems.	NCA	2007	DBLP DOI BibTeX RDF
26	Munehiro Fukuda, Koichi Kashiwagi, Shin-ya Kobayashi	AgentTeamwork: Coordinating grid-computing jobs with mobile agents.	Appl. Intell.	2006	DBLP DOI BibTeX RDF	Fault tolerance, Grid computing, Mobile agents, Process migration, Middleware design
26	Xinjian Chen 0001, Jie Tian 0001, Yangyang Zhang, Xin Yang 0001	A Robust Orientation Estimation Algorithm for Low Quality Fingerprints.	IWBRS	2005	DBLP DOI BibTeX RDF
26	Daniel R. L. Brown, Don B. Johnson	Formal Security Proofs for a Signature Scheme with Partial Message Recovery.	CT-RSA	2001	DBLP DOI BibTeX RDF
26	Carlos Pérez, Germán Fabregat, Rafael J. Martínez, Juan J. Villaplana	TREG: Transactional Services Based on Incremental Messages.	PRDC	2001	DBLP DOI BibTeX RDF	incremental messages, operating systems, checkpointing, Transactional systems, replicated data management
26	Amir A. Amini	A Scalar Function Formulation for Optical Flow.	ECCV (1)	1994	DBLP DOI BibTeX RDF
26	Srikanth Kambhatla, Jonathan Walpole	Recovery with limited replay: fault-tolerant processes in Linda.	SPDP	1990	DBLP DOI BibTeX RDF
26	Jeannette M. Wing	Specifying Avalon Objects in Larch.	TAPSOFT, Vol.2	1989	DBLP DOI BibTeX RDF
23	Baruch Awerbuch, David Peleg	Online Tracking of Mobile Users.	J. ACM	1995	DBLP DOI BibTeX RDF	bounded packet header, bounded protocol, ideal transmission cost, non-FIFO channels, receiver-driven protocol, recoverable protocol, recovery cost, sequence transmission problem, lookahead
23	Luis-Felipe Cabrera, John McPherson, Peter M. Schwarz, James C. Wyllie	Implementing Atomicity in Two Systems: Techniques, Tradeoffs, and Experience.	IEEE Trans. Software Eng.	1993	DBLP DOI BibTeX RDF	QuickSilver distributed file system, Starburst relational database manager, atomic properties, mutual consistency, client-server transactions, recoverable data structures, shadow copies, concurrency, relational databases, distributed databases, transaction processing, atomicity, network operating systems, stable storage, transaction systems
23	John J. Shedletsky	Error Correction by Alternate-Data Retry.	IEEE Trans. Computers	1978	DBLP DOI BibTeX RDF	Alternate-data retry (ADR), fault neutralization, morphic circuits, availability, error correction, self-checking, recoverable
17	María Chara, F. Galluccio, Edgar Martínez-Moro	Locally recoverable codes from towers of function fields.	Finite Fields Their Appl.	2024	DBLP DOI BibTeX RDF
17	Morris Ching-Hung Tsai, Scott C.-H. Huang, Hsiao-Chun Wu	Novel Recoverable Audio Mosaic Technique Using Segmental and Hierarchical Permutations.	IEEE Internet Things J.	2024	DBLP DOI BibTeX RDF
17	Yuxin Bai, Chen Xin, Xinjie Zhou, Yanan Yin, Ying Zhang	Double-Node-Upset Self-Recoverable Latch Design for Wide Voltage Range Application.	IEEE Trans. Circuits Syst. II Express Briefs	2024	DBLP DOI BibTeX RDF
17	Akram Baghban, Marc Newman, Anna-Lena Horlemann, Mehdi Ghiyasvand	q-ary Sequential Locally Recoverable Codes from the Product Construction.	CoRR	2024	DBLP DOI BibTeX RDF
17	Xuening Tang, Xianghui Cao, Wei-Xing Zheng 0001	A Control-Recoverable Added-Noise-based Privacy Scheme for LQ Control in Networked Control Systems.	CoRR	2024	DBLP DOI BibTeX RDF
17	Marcel Jackiewicz, Adam Kasperski, Pawel Zielinski 0001	Computational Complexity of the Recoverable Robust Shortest Path Problem with Discrete Recourse.	CoRR	2024	DBLP DOI BibTeX RDF
17	Sascha Kurz	Bounds on the minimum distance of locally recoverable codes.	CoRR	2024	DBLP DOI BibTeX RDF
17	Giulia Cavicchioni, Eleonora Guerrini, Alessio Meneghetti	A class of locally recoverable codes over finite chain rings.	CoRR	2024	DBLP DOI BibTeX RDF
17	Marcel Jackiewicz, Adam Kasperski, Pawel Zielinski 0001	Recoverable robust shortest path problem under interval uncertainty representations.	CoRR	2024	DBLP DOI BibTeX RDF
17	Yuqing Huang, Xin Li, Zikun Zhou, Yaowei Wang, Zhenyu He 0001, Ming-Hsuan Yang 0001	RTracker: Recoverable Tracking via PN Tree Structured Memory.	CoRR	2024	DBLP DOI BibTeX RDF
17	Dean Doron, S. Venkitesh	Random Reed-Solomon Codes are List Recoverable with Optimal List Size.	CoRR	2024	DBLP DOI BibTeX RDF
17	Mohammad Shadman Ishrak, Jannatun Noor Sameera, Olga Boric-Lubecke, Victor M. Lubecke	Parametric Classification of Recoverable Radar-Assessed Respiratory Rate Data.	RWS	2024	DBLP DOI BibTeX RDF
17	Christoph Grüne	The Complexity Classes of Hamming Distance Recoverable Robust Problems.	LATIN (1)	2024	DBLP DOI BibTeX RDF
17	Xiaoru Li, Ziling Heng	Constructions of near MDS codes which are optimal locally recoverable codes.	Finite Fields Their Appl.	2023	DBLP DOI BibTeX RDF
17	Shuo Cai, Caicai Xie, Yan Wen, Weizheng Wang, Fei Yu 0009, Lairong Yin	Four-input-C-element-based multiple-node-upset-self-recoverable latch designs.	Integr.	2023	DBLP DOI BibTeX RDF
17	Zhengfeng Huang, Dongxing Ma, Runwu Ji, Huaguo Liang, Aibin Yan, Tai Song, Tianming Ni	Overhead Optimized and Quadruple-Node-Upset Self-Recoverable Latch Design Based on Looped C-Element Matrix.	IEEE Trans. Aerosp. Electron. Syst.	2023	DBLP DOI BibTeX RDF
17	Aibin Yan, Zhixing Li, Jie Cui 0004, Zhengfeng Huang, Tianming Ni, Patrick Girard 0001, Xiaoqing Wen	Designs of Two Quadruple-Node-Upset Self-Recoverable Latches for Highly Robust Computing in Harsh Radiation Environments.	IEEE Trans. Aerosp. Electron. Syst.	2023	DBLP DOI BibTeX RDF
17	Soumitra Pal 0002, Gajendranath Chowdary, Wing-Hung Ki, Chi-Ying Tsui	Energy-Efficient Dual-Node-Upset-Recoverable 12T SRAM for Low-Power Aerospace Applications.	IEEE Access	2023	DBLP DOI BibTeX RDF
17	Seyedehsomayeh Hatefinasab, Alfredo Medina-Garcia, Diego Pedro Morales, Encarnación Castillo, Noel Rodriguez	Rule-Based Design for Low-Cost Double-Node Upset Tolerant Self-Recoverable D-Latch.	IEEE Access	2023	DBLP DOI BibTeX RDF
17	Xiaoxue Cao, Jiahao Lin, Shaoxiong Wu, Srikrishna Chanakya Bodepudi, Zongwen Li, Feng Tian, Zheng Li, Xinyu Liu 0016, Li Peng, Chao Gao, Yang Xu 0035	Recoverable Patterning of Macro-Assembled Graphene Nanofilms.	IEEE Access	2023	DBLP DOI BibTeX RDF
17	Fagang Li, Hao Chen 0029, Huimin Lao, Shanxiang Lyu	New upper bounds and constructions of multi-erasure locally recoverable codes.	Cryptogr. Commun.	2023	DBLP DOI BibTeX RDF
17	Xiaoru Li, Ziling Heng	A construction of optimal locally recoverable codes.	Cryptogr. Commun.	2023	DBLP DOI BibTeX RDF
17	María Chara, Sam Kottler, Beth Malmskog, Bianca Thompson, Mckenzie West	Minimum distance and parameter ranges of locally recoverable codes with availability from fiber products of curves.	Des. Codes Cryptogr.	2023	DBLP DOI BibTeX RDF
17	Li Xu, Zhengchun Zhou, Jun Zhang, Sihem Mesnager	Optimal quaternary (r,δ )-locally recoverable codes: their structures and complete classification.	Des. Codes Cryptogr.	2023	DBLP DOI BibTeX RDF
17	Jiawei Zhang, Jinwei Wang, Hao Wang 0060, Xiangyang Luo	Self-Recoverable Adversarial Examples: A New Effective Protection Mechanism in Social Networks.	IEEE Trans. Circuits Syst. Video Technol.	2023	DBLP DOI BibTeX RDF
17	Jin-Liang Wang, Lu Wang, Huai-Ning Wu	Synchronization for Complex Networks With Multiple State or Delayed State Couplings Under Recoverable Attacks.	IEEE Trans. Syst. Man Cybern. Syst.	2023	DBLP DOI BibTeX RDF
17	Arya Mazumdar	Capacity of Locally Recoverable Codes.	IEEE J. Sel. Areas Inf. Theory	2023	DBLP DOI BibTeX RDF
17	Louis Golowich, Venkatesan Guruswami	Quantum Locally Recoverable Codes.	Electron. Colloquium Comput. Complex.	2023	DBLP BibTeX RDF
17	D. Shivakrishna, Aaditya M. Nair, V. Lalitha 0001	Maximally Recoverable Codes With Hierarchical Locality: Constructions and Field-Size Bounds.	IEEE Trans. Inf. Theory	2023	DBLP DOI BibTeX RDF
17	Shu Liu 0004, Chaoping Xing	Maximally Recoverable Local Repairable Codes From Subspace Direct Sum Systems.	IEEE Trans. Inf. Theory	2023	DBLP DOI BibTeX RDF
17	Austin Dukes, Giacomo Micheli, Vincenzo Pallozzi Lavorante	Optimal Locally Recoverable Codes With Hierarchy From Nested F-Adic Expansions.	IEEE Trans. Inf. Theory	2023	DBLP DOI BibTeX RDF
17	Kathryn Haymaker, Beth Malmskog, Gretchen L. Matthews	Algebraic hierarchical locally recoverable codes with nested affine subspace recovery.	CoRR	2023	DBLP DOI BibTeX RDF
17	Mouxiang Chen, Chenghao Liu, Zemin Liu, Zhuo Li, Jianling Sun	Identifiability Matters: Revealing the Hidden Recoverable Condition in Unbiased Learning to Rank.	CoRR	2023	DBLP DOI BibTeX RDF
17	Tomer Lev Lehman, Hagit Attiya, Danny Hendler	Recoverable and Detectable Self-Implementations of Swap.	CoRR	2023	DBLP DOI BibTeX RDF
17	Andrea Ferraguti, Dorian Goldfeld, Giacomo Micheli	Number Theoretical Locally Recoverable Codes.	CoRR	2023	DBLP DOI BibTeX RDF
17	Prasad Jayanti, Siddhartha Jayanti, Anup Joshi	Constant RMR Recoverable Mutex under System-wide Crashes.	CoRR	2023	DBLP DOI BibTeX RDF
17	Rui Song	LinkDID: A Privacy-Preserving, Sybil-Resistant and Key-Recoverable Decentralized Identity Scheme.	CoRR	2023	DBLP DOI BibTeX RDF
17	Jun Liu 0071, Jiantao Zhou 0001, Jinyu Tian, Weiwei Sun 0009	Recoverable Privacy-Preserving Image Classification through Noise-like Adversarial Examples.	CoRR	2023	DBLP DOI BibTeX RDF
17	Carlos Galindo 0001, Fernando Hernando, Carlos Munuera, Diego Ruano	Locally recoverable codes from the matrix-product construction.	CoRR	2023	DBLP DOI BibTeX RDF
17	Felix Hommelsheim, Nicole Megow, Komal Muluk, Britta Peis	Recoverable Robust Optimization with Commitment.	CoRR	2023	DBLP DOI BibTeX RDF
17	Louis Golowich, Venkatesan Guruswami	Quantum Locally Recoverable Codes.	CoRR	2023	DBLP DOI BibTeX RDF
17	Alexander Barg, Ohad Elishco, Ryan Gabrys, Geyang Wang, Eitan Yaakobi	Storage codes and recoverable systems on lines and grids.	CoRR	2023	DBLP DOI BibTeX RDF
17	Kaili Wang, Qinchen Wang, Calvin Cai, Dan Boneh	R-Pool and Settlement Markets for Recoverable ERC-20R Tokens.	CoRR	2023	DBLP DOI BibTeX RDF
17	Yaozong Zhang, Dabin Zheng, Xiaoqiang Wang 0001	Three classes of new optimal cyclic (r, δ) locally recoverable codes.	CoRR	2023	DBLP DOI BibTeX RDF
17	Gaojun Luo, Bocong Chen, Martianus Frederic Ezerman, San Ling	Bounds and Constructions of Quantum Locally Recoverable Codes from Quantum CSS Codes.	CoRR	2023	DBLP DOI BibTeX RDF
17	Marcel Jackiewicz, Adam Kasperski, Pawel Zielinski 0001	Solving the recoverable robust shortest path problem in DAGs.	CoRR	2023	DBLP DOI BibTeX RDF