141 research outputs found

    An asymptotic existence result on compressed sensing matrices

    Get PDF
    For any rational number hh and all sufficiently large nn we give a deterministic construction for an n×hnn\times \lfloor hn\rfloor compressed sensing matrix with (1,t)(\ell_1,t)-recoverability where t=O(n)t=O(\sqrt{n}). Our method uses pairwise balanced designs and complex Hadamard matrices in the construction of ϵ\epsilon-equiangular frames, which we introduce as a generalisation of equiangular tight frames. The method is general and produces good compressed sensing matrices from any appropriately chosen pairwise balanced design. The (1,t)(\ell_1,t)-recoverability performance is specified as a simple function of the parameters of the design. To obtain our asymptotic existence result we prove new results on the existence of pairwise balanced designs in which the numbers of blocks of each size are specified.Comment: 15 pages, no figures. Minor improvements and updates in February 201

    Perfect Hash Families: The Generalization to Higher Indices

    Get PDF
    Perfect hash families are often represented as combinatorial arrays encoding partitions of kitems into v classes, so that every t or fewer of the items are completely separated by at least a specified number of chosen partitions. This specified number is the index of the hash family. The case when each t-set must be separated at least once has been extensively researched; they arise in diverse applications, both directly and as fundamental ingredients in a column replacement strategy for a variety of combinatorial arrays. In this paper, construction techniques and algorithmic methods for constructing perfect hash families are surveyed, in order to explore extensions to the situation when each t-set must be separated by more than one partition.https://digitalcommons.usmalibrary.org/books/1029/thumbnail.jp

    Research on the Internet of Things (IoT)

    Get PDF
    The Internet of things (IoT) has become a research hotspot in computer science. The fact it will lead to a new information revolution is considered by most researchers. The main idea of IoT is that all objects are connected to the Internet and thus to be managed and controlled remotely, even interact with each other by receiving and sending information as well as sense their surroundings and have a certain reaction through intelligent technologies. In this paper, we firstly introduce the definition and connotation of IoT briefly. Secondly, we present the enabling technologies of IoT such as RFID (Radio Frequency Identification) systems, WSN (wireless sensor networks), intelligent technologies, NT (nanotechnology), addressing schemes, data storage and analysis and visualization. Thirdly, we give a brief introduce of the applications of IoT. It includes individuals and families, enterprise, public utilities and mobile. Fourthly, some open issues and research directions are introduced. Finally, we give the conclusion

    Crowdfunding Non-fungible Tokens on the Blockchain

    Get PDF
    Non-fungible tokens (NFTs) have been used as a way of rewarding content creators. Artists publish their works on the blockchain as NFTs, which they can then sell. The buyer of an NFT then holds ownership of a unique digital asset, which can be resold in much the same way that real-world art collectors might trade paintings. However, while a deal of effort has been spent on selling works of art on the blockchain, very little attention has been paid to using the blockchain as a means of fundraising to help finance the artist’s work in the first place. Additionally, while blockchains like Ethereum are ideal for smaller works of art, additional support is needed when the artwork is larger than is feasible to store on the blockchain. In this paper, we propose a fundraising mechanism that will help artists to gain financial support for their initiatives, and where the backers can receive a share of the profits in exchange for their support. We discuss our prototype implementation using the SpartanGold framework. We then discuss how this system could be expanded to support large NFTs with the 0Chain blockchain, and describe how we could provide support for ongoing storage of these NFTs

    Fake Malware Generation Using HMM and GAN

    Get PDF
    In the past decade, the number of malware attacks have grown considerably and, more importantly, evolved. Many researchers have successfully integrated state-of-the-art machine learning techniques to combat this ever present and rising threat to information security. However, the lack of enough data to appropriately train these machine learning models is one big challenge that is still present. Generative modelling has proven to be very efficient at generating image-like synthesized data that can match the actual data distribution. In this paper, we aim to generate malware samples as opcode sequences and attempt to differentiate them from the real ones with the goal to build fake malware data that can be used to effectively train the machine learning models. We use and compare different Generative Adversarial Networks (GAN) algorithms and Hidden Markov Models (HMM) to generate such fake samples obtaining promising results

    Numerical investigation of fracture of polycrystalline ice under dynamic loading

    Get PDF
    Cohesive zone model is a promising technique for simulating fracture processes in brittle ice. In this work it is applied to investigate the fracture behavior of polycrystalline cylindrical samples under uniaxial loading conditions, four-point beam bending, and L-shaped beam bending. In each case, the simulation results are compared with the corresponding experimental data that was collected by other researchers. The model is based on the implicit finite element method combined with Park-Paulino-Roesler formulation for cohesive potential and includes an adaptive time stepping scheme, which takes into account the rate of damage and failure of cohesive zones. The benefit of the implicit scheme is that it allows larger time steps than explicit integration. Material properties and model parameters are calibrated using available experimental data for freshwater ice and sea ice samples. For polycrystalline ice, granular geometry is generated and cohesive zones are inserted between grains. Simulations are performed for samples with different grain sizes, and the resulting stress–strain and damage accumulation curves are recorded. Investigation of the dependency between the grain size and fracture strength shows a strengthening effect that is consistent with experimental results. The proposed framework is also applied to simulate the dynamic fracture processes in Lshaped beams of sea ice, in which case the cohesive zones are inserted between the elements of the mesh. Evolution of the stress distribution on the surface of the beam is modeled for the duration of the loading process, showing how it changes with progressive accumulation of damage in the material, as well as the development of cracks. An analytical formula is derived for estimating the breaking force based on the dimensions of the beam and the ice strength. Experimental data obtained from the 2014-2016 tests are re-evaluated with the aid of this new analysis. The computation is implemented efficiently with GPU acceleration, allowing to handle geometries with higher resolution than would be possible otherwise. Several technical contributions are described in detail including GPU-accelerated FEM implementation, an efficient way of creation of sparse matrix structure, and comparison of different unloading/reloading relations when using an implicit integration scheme. A mechanism for collision response allows modeling the interaction of fragmented material. To evaluate the collision forces, an algorithm for computing first and second point-triangle distance derivatives was developed. The source code is made available as open-source

    Instrumented Indentation for Characterization of Irradiated Metals at Room and High Temperatures

    Get PDF

    Pertanika Journal of Science & Technology

    Get PDF

    Pertanika Journal of Science & Technology

    Get PDF
    corecore