Jen‐Shiun Chiang, Hsin‐Ting Li, Chih‐Hsien Hsia et al. · 2013
Since the data storage capacity per unit area of a QR code is very limited, it is restricted in various QR code applications. In this work, we propose an approach based on visual skew to improve the data capacity of the QR code. Our method can enhance the capacity of the QR code per unit area by using different angle views to combine several QR codes together. The storage capacity of the proposed mechanism can be increased by 1.5 times per unit area more than that of the normal QR-code.
Cited by 5
Milan Simić · 2011
Design of a new Run Length Limited (RLL) code is presented. The new coding scheme has coding rate of R=2/5, with the minimum runlength between two successive transitions equal to 4. This RLL (4, ∞) code uses channel capacity extremely efficiently, 98.7% and consequently it achieves density rate of DR=2.0. It has better efficiency than many other currently used codes for high density optical recording, or transmission.
Cited by 4
Eardley, Jon · Zenodo (CERN European Organization for Nuclear Research) · 2025
Density
Cited by 0Open access
Digkas, George, Chatzigeorgiou, Alexander, Ampatzoglou, Apostolos et al. · arXiv (Cornell University) · 2020
While technical debt grows in absolute numbers as software systems evolve over time, the density of technical debt (technical debt divided by lines of code) is reduced in some cases. This can be explained by either the application of refactorings or the development of new artifacts with limited Technical Debt. In this paper we explore the second explanation, by investigating the relation between the amount of Technical Debt in new code and the evolution of Technical Debt in the system. To this end, we compare the Technical Debt Density of new code with existing code, and we investigate which of the three major types of code changes (additions, deletions and modifications) is primarily responsible for changes in the evolution of Technical Debt density. Furthermore, we study whether there is a relation between code quality practices and the 'cleanness' of new code. To obtain the required data, we have performed a large-scale case study on twenty-seven open-source software projects by the Apache Software Foundation, analyzing 66,661 classes and 56,890 commits. The results suggest that writing "clean" (or at least "cleaner") new code can be an efficient strategy for reducing Technical Debt Density, and thus preventing software decay over time. The findings also suggest that projects adopting an explicit policy for quality improvement, e.g. through discussions on code quality in board meetings, are associated with a higher frequency of cleaner new code commits. Therefore, we champion the establishment of processes that monitor the density of Technical Debt of new code to control the accumulation of Technical Debt in a software system.
Cited by 0Open access
Jen‐Shiun Chiang, Chih‐Hsien Hsia, Hsin‐Ting Li · Electronics Letters · 2013
Since the data storage capacity per unit area of a QR code is very limited, it is restricted in various QR code applications. An approach is proposed based on visual skew to improve the data capacity of the QR code. The proposed method can enhance the capacity of the QR code per unit area by using different angle views to combine several QR codes together. The storage capacity of the proposed mechanism can be increased 1.5 times per unit area more than that of the normal QR code.
Cited by 10Open access
江正雄; 夏至賢 · 2013
EI
Cited by 0
Cook, Chelsea N. · Figshare · 2025
Social animals exhibit complex, coordinated behaviors that can drive significant environmental change. Within groups, individuals sense their environment and share information to facilitate collective action. Direct physical contact is a key mechanism of communication in many social species, yet its role in organizing collective behaviors remains underexplored. Here, we investigate how tactile interactions influence thermoregulatory fanning behavior in honey bees (<i>Apis mellifera</i>), a critical collective response to environmental stress. By reducing the ability of bees to engage in physical contact, we demonstrated that direct tactile interactions are necessary to initiate and coordinate fanning. Increasing social density by modulating spatial constraints further enhanced the probability of fanning. Using video tracking, we confirmed that elevated social densities resulted in more frequent direct contacts, identifying tactile interactions—specifically head-to-head contacts—as a driver of fanning behavior. Our findings highlight tactile communication as a mechanism for information transfer in an ecologically relevant collective behavior. By elucidating how social interactions mediate environmental responses, this work contributes to our understanding of the resilience of social systems in a rapidly changing world.
Cited by 0Open access
A. M. Patel, S. J. Hong · IBM Journal of Research and Development · 1974
IBM's 6250 bpi 3420 series tape units require a powerful error-correcting code for the standard 9-track format. The optimal rectangular code (ORC), presented here, is designed to correct any single-track error or, given erasure pointers, any double-track error in the tape. The code achieves this by conforming to a rectangular codeword of which two orthogonal sides are check bits. The code is specially tailored from a general class of b-adjacent codes. The ORC can be implemented without a buffer for encoding and offers a simple error-correction mechanism. The code can be generalized to multiple-channel applications.
Cited by 44
Liu, Qiao · Zenodo (CERN European Organization for Nuclear Research) · 2021
The source code for implementing the Roundtrip model, which can be used for density estimation. One can also refer to Github repository: <strong>https://github.com/kimmo1019/Roundtrip</strong> for more details.
Cited by 0Open access
Humeniuk, Alexander · Zenodo (CERN European Organization for Nuclear Research) · 2024
This python package implements approximate multistate matrix functionals for the electron-electron repulsion and the kinetic energy to be used in multistate density functional theory (MSDFT). The code can be used to reproduce the calculations and figures from the preprint A. Humeniuk, "Approximate Functionals for Multistate Density functional Theory", ChemRxiv (2024).
Cited by 0Open access
Amico, Tommaso, Matthews, Pernille, Assent, Ira et al. · Zenodo (CERN European Organization for Nuclear Research) · 2025
This is the code for "DCFO: Density-Based Counterfactuals for Outliers", accepted at SIGKDD 2026
Cited by 0Open access
George Digkas, Alexander Chatzigeorgiou, Apostolos Ampatzoglou et al. · IEEE Transactions on Software Engineering · 2020
While technical debt grows in absolute numbers as software systems evolve over time, the density of technical debt (technical debt divided by lines of code) is reduced in some cases. This can be explained by either the application of refactorings or the development of new artifacts with limited Technical Debt. In this paper we explore the second explanation, by investigating the relation between the amount of Technical Debt in new code and the evolution of Technical Debt in the system. To this end, we compare the Technical Debt Density of new code with existing code, and we investigate which of the three major types of code changes (additions, deletions and modifications) is primarily responsible for changes in the evolution of Technical Debt density. Furthermore, we study whether there is a relation between code quality practices and the ‘cleanness’ of new code. To obtain the required data, we have performed a large-scale case study on twenty-seven open-source software projects by the Apache Software Foundation, analyzing 66,661 classes and 56,890 commits. The results suggest that writing “clean” (or at least “cleaner”) new code can be an efficient strategy for reducing Technical Debt Density, and thus preventing software decay over time. The findings also suggest that projects adopting an explicit policy for quality improvement, e.g., through discussions on code quality in board meetings, are associated with a higher frequency of cleaner new code commits. Therefore, we champion the establishment of processes that monitor the density of Technical Debt of new code to control the accumulation of Technical Debt in a software system.
Cited by 36Open access
Andrew C. Yuan, Alexander Cowtan, Zhiyang He et al. · arXiv (Cornell University) · 2026
Quantum code surgery offers a flexible, low-overhead framework for executing logical measurements within quantum error-correcting codes. It encompasses several fault-tolerant logical computation schemes, including parallel surgery, universal adapters and fast surgery, and serves as the key primitive in extractor architectures. The efficiency of these schemes crucially depends on constructing low-overhead ancilla systems for measuring arbitrary logical operators in general quantum Low-Density Parity-Check (qLDPC) codes. In this work, we introduce a method to construct an ancilla system of qubit size $O(W \log W)$ to measure an arbitrary logical Pauli operator of weight $W$ in any qLDPC stabilizer code. This new construction immediately reduces the asymptotic overhead across various quantum code surgery schemes.
Cited by 0Open access
Jayasooriya, Jayasooriya Arachchige Sachini Nisansala · NOVA (University of Newcastle, Australia) · 2017
The field of error correcting codes has been revolutionized by the introduction of graph-based codes, such as low-density parity-check (LDPC) codes and turbo codes. These codes exhibit dramatic performance improvement with significantly lower decoding complexity over previously developed coding schemes such as Hamming codes and BCH codes, which are overwhelmingly algebraic. Since then, understanding the performance of these codes, and using this understanding to design capacity-approaching codes, is one of the utmost subjects of interest among coding specialists. This thesis adds to this field, developing analytical tools and supporting theory for designing capacity-approaching codes using the concept of multi-edge parametrization. The benefit of multi-edge parametrization is greater flexibility in code structure, which enables the specification of graphs not possible in the standard LDPC framework. The first two parts of this thesis are dedicated to developing analytical tools for graph-based codes. In the first part, we consider the design of LDPC and multi-edge type LDPC (MET-LDPC) codes, and propose an algorithm to jointly optimize the node degree distribution and the code structure of a code ensemble for given values of the maximum number of edge-types and maximum node degrees. This joint optimization is particularly important for MET-LDPC codes, because it systematically finds good MET-LDPC code structures as opposed to trial and error or intuition in conventional approaches. In the second part, we consider density evolution (DE) for LDPC and MET-LDPC codes over the binary input additive white Gaussian noise (BI-AWGN) channel. We analyze several single-parameter Gaussian approximations for DE and show that the assumption of symmetric Gaussian distribution for the DE messages is not accurate in the early decoding iterations, particularly at low rates and with punctured variable nodes. Based on these observations, we introduce a new DE approximation algorithm for LDPC and MET-LDPC codes, which is a combination of full density evolution (full-DE) and a single-parameter Gaussian approximation, where we assume a symmetric Gaussian distribution only after DE messages closely follow a symmetric Gaussian distribution. The proposed method improves the accuracy of the code threshold estimation. In addition, it significantly reduces the computational time of evaluating the code threshold compared with full-DE, thereby making it more suitable for code design. In the final part of this thesis, we employ the analytical tools designed in the first part to the problem of code design for rateless coding, in particular for Raptor codes. The main focus of this part is to analyze and design Raptor codes over a BI-AWGN channel using a multi-edge framework. We first propose a new representation of Raptor codes as MET-LDPC codes and then apply analytical tools developed in the first part of this thesis to design them. The benefit of multi-edge representation of Raptor codes is that it enables us to perform a comprehensive analysis of the asymptotic performance of Raptor codes using MET density evolution. We consider two decoding schemes based on the belief propagation (BP) decoding, namely tandem decoding and joint decoding in the multi-edge framework, and analyze the convergence behavior of the BP decoder. Finally, we extend the analysis to design higher-order modulated Raptor codes using the multi-edge framework.
Cited by 0Open access
Richard Lahman, Hyuck M. Kwon · 2023
In wireless terrestrial or satellite communications systems, the communication system engineers use many factors and techniques to combat the channel degradation. For example, the digital video broadcasting – second generation (DVB-S2) satellite communication system includes the adaptive code modulation (ACM), i.e., various combinations of modulation types and forward error correction (FEC) code rates. The Bose-Chaudhuri-Hocquenghem (BCH) code and low-density parity-check (LDPC) with various code rates are used as FEC codes to reduce the channel degradation. On the other hand, the polar FEC code is a more recently developed technique than the LDPC FEC code and has been used in fifth-generation (5G), third-generation partnership project (3GPP) wireless terrestrial communications to improve the channel capacity. The 5G 3GPP terrestrial communications also use the orthogonal frequency-division multiplexing (OFDM) modulation in addition to the polar FEC code. The objective of this paper is to study how to replace the LDPC FEC code in the DVB-S2 satellite communication system with the 5G terrestrial polar FEC code and OFDM, and compare bit error rate (BER) performance under the multipath Rayleigh fading channel environment. All other components in the DVB-S2 system, such as code word length, interleaver size, modulation, etc., are unchanged. This paper investigates the performance of the DVB-S2 ACM scheme by replacing the LDPC FEC code with the polar FEC code, and presents the required symbol energy-to-noise power spectral density ratio to achieve a BER equal to 10<inf>−5</inf>. Then, this paper claims that performance over the current DVB-S2 communication system can be enhanced by using the polar FEC code and OFDM.
Cited by 0
Brian K. Butler, Paul H. Siegel · arXiv (Cornell University) · 2014
This short paper explores density evolution (DE) for low-density parity-check (LDPC) codes at signal-to-noise-ratios (SNRs) that are significantly above the decoding threshold. The focus is on the additive white Gaussian noise channel and LDPC codes in which the variable nodes have regular degree. Prior work, using DE, produced results in the error floor region which were asymptotic in the belief-propagation decoder's log-likelihood ratio (LLR) values. We develop expressions which closely approximate the LLR growth behavior at moderate LLR magnitudes. We then produce bounds on the mean extrinsic check-node LLR values required, as a function of SNR, such that the growth rate of the LLRs exceeds that of a particular trapping set's internal LLRs such that its error floor contribution may be eliminated. We find that our predictions for the mean LLRs to be accurate in the error floor region, but the predictions for the LLR variance to be lacking beyond several initial iterations.
Cited by 1Open access
Peter Steenkiste · 1989
The widespread use of reduced-instruction-set computers has generated a lot of interest in the tradeoff between the density of an instruction set and the size of the instruction cache. In this paper we present and justify a method that predicts the cache performance for a wide range of architectures, based on the miss rate for a single architecture. When we apply the method to a number of cache organizations we find that changes in code density can have a dramatic impact on memory traffic, but that modest improvements in code density do not reduce program execution time significantly in a well-balanced system.
Cited by 15Open access
Apr W L Oliver F--c, I Endc, W. L. Oliver · 1980
ivail and/or EL a Dist speclal Approved for public release; distribution unlimited. AG5 18 D LEXINGTON MASSACHUSETTS$J
Cited by 0
Hoffman, G. W., U.S. Atomic Energy Commission., Bettis Atomic Power Laboratory. · The Journal of the Abraham Lincoln Association
"Bettis Plant, Pittsburgh, Pa., operated for the U.S. Atomic Energy Commission by Westinghouse Electric Corporation."
Cited by 0Open access
Georgi Gaydadjiev, Stamatis Vassiliadis · Lecture notes in computer science · 2004
Cited by 1Open access