64 research outputs found
Construction of Optimal Locally Recoverable Codes and Connection with Hypergraph
No full textLocally recoverable codes are a class of block codes with an additional property called locality. A locally recoverable code with locality r can recover a symbol by reading at most r other symbols. Recently, it was discovered by several authors that a q-ary optimal locally recoverable code, i.e., a locally recoverable code achieving the Singleton-type bound, can have length much bigger than q+1. In this paper, we present both the upper bound and the lower bound on the length of optimal locally recoverable codes. Our lower bound improves the best known result in [Yuan Luo et al., 2018] for all distance d >= 7. This result is built on the observation of the parity-check matrix equipped with the Vandermonde structure. It turns out that a parity-check matrix with the Vandermonde structure produces an optimal locally recoverable code if it satisfies a certain expansion property for subsets of F_q. To our surprise, this expansion property is then shown to be equivalent to a well-studied problem in extremal graph theory. Our upper bound is derived by an refined analysis of the arguments of Theorem 3.3 in [Venkatesan Guruswami et al., 2018]
Epidemiology and Outcomes of Acute Kidney Injury in COVID-19 Patients with Acute Respiratory Distress Syndrome: A Multicenter Retrospective Study
No full textBackground: Acute kidney injury (AKI) is associated with increased mortality in patients with acute respiratory distress syndrome (ARDS). However, the epidemiological features and outcomes of AKI among COVID-19 patients with ARDS are unknown. Methods: We retrospectively recruited consecutive adult COVID-19 patients who were diagnosed with ARDS according to Berlin definition from 13 designated intensive care units in the city of Wuhan, China. Potential risk factors of AKI as well as the relation between AKI and in-hospital mortality were investigated. Results: A total of 275 COVID-19 patients with ARDS were included in the study, and 49.5% of them developed AKI during their hospital stay. In comparison with patients without AKI, patients who developed AKI were older, tended to have chronic kidney disease, had higher Sepsis-Related Organ Failure Assessment score on day 1, and were more likely to receive invasive ventilation and develop acute organ dysfunction. Multivariate analysis showe..
The Research on Exogenous Problems of Farmers’ Piritual and Cultural Education in China
No full textThe author studied and analyzed the exogenous problems of the farmers’ spiritual and cultural education, and found out: In today’s China, the exogenous problems of the farmers’ spiritual and cultural education mainly reflected in the separation of spiritual and cultural education is from social environment, political system, economic development, and cultural concepts etc. Then the author put forward to the countermeasures and suggestions aimed at optimizing the allocation of famers’ spiritual and cultural educations resources, environment and evaluation system construction and so on
Caracterización geológica de la formación Hollín al noreste del campo Yuralpa en la Cuenca Oriente
No full textEl área de estudio se encuentra ubicado en el sector noreste del campo Yuralpa, perteneciente al bloque 21 en la zona occidental de la cuenca Oriente de Ecuador. El yacimiento pertenece al flanco extendido del anticlinal asimétrico cuyo eje tiene una orientación preferencial NNE-SSO.
A través del procesamiento y análisis de la información proporcionada por la empresa Wayra Energy SA se caracterizó al reservorio Hollín de acuerdo a su litología y ambiente de depositación, siendo; el intervalo inferior de areniscas de grano grueso a medio depositados en un ambiente fluvial de ríos entrelazados; y el intervalo superior, caracterizado a la base de areniscas de grano medio - fino depositado en un ambiente dominado por mareas, y al tope una arenisca de grano fino bioturbada con presencia de glauconita depositada en un ambiente marino profundo.
De acuerdo con la caracterización petrofísica y geológica realizadas, el cálculo del petróleo original en sito (POES) por el método geoestadístico da un total de 24´581 289 Bls, siendo 22´932 802 en el intervalo superior y 1´654 845 en el intervalo inferior. Las mejores propiedades petrofísicas se encuentran a la base del intervalo Hollín superior con un promedio de 15% de porosidad efectiva y 23% de saturación de agua.The area that has studied is located in the northeast of the Yuralpa field, it belongs in the 21 part of the Oriente Basin of Ecuador. The deposit belongs in the extended flank of the asymmetric anticline whose axis has an NNE-SSO orientation.
Through the process and analysis of the information provided by the company Wayra Energy SA, the Hollín reservoir was characterized according to its lithology and deposition environment, being; the lower range of coarse-grained sandstones deposited in a river environment of braided rivers; and the upper range is characterized to the base of medium-grained sandstones deposited in a tidal environment, and to the top composed of a fine-grained, bioturbed sandstone with the presence of glauconite deposited in a deep marine environment.
According of the petrophysical and geological characterization, the calculation of the original oil on site (POES) by the geostatistical method gave a total of 24'581 289 Bls, being 22'932 802 in the upper interval and 1'654 845 in the lower interval. The best petrophysical properties are found in the base of the upper soot interval with an average of 15% effective porosity and 23% water saturation
Graph Encryption for Shortest Path Queries with k Unsorted Nodes
No full textShortest distance queries over large-scale graphs bring great benefits to various applications, i.e., save planning time and travelling expenses. To protect the sensitive nodes and edges in the graph, a user outsources an encrypted graph to an untrusted server without losing the query ability. However, no prior work has considered the user requirement of the shortest path with k unsorted nodes. In particular, we are concerned with how to securely find the shortest path by passing k nodes that do not have a fixed traverse order. To solve the problems, we propose Gespun (stands for Graph encryption for shortest path queries with k unordered nodes). It includes an oracle encryption scheme that is provably secure against the semi-honest server. Specifically, we compute the shortest paths and distances for all nodes locally to obtain path-distance oracles. We transform the shortest paths to a sequence of secure codes by using a pseudo-random permutation to protect the structure privacy. We encrypt the shortest distance by using additively homomorphic encryption. Second, we pack the oracles in link-list nodes and store them in an array-based dictionary after another permutation. Next, we construct a search graph to compute the shortest path while guaranteeing that the path passes the required k nodes. We formally prove that Gespun is adaptively semantically-secure in the random oracle. We implement a prototype of Gespun and evaluate its performance. Experiments results demonstrate that Gespun is efficient, e.g., a query over 6301 nodes, 20777 edges, and 5 unsorted nodes only needs 483 ms to get queried results. We believe that our research problem span new research that soon promotes a new line of graph encryption schemes.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Cyber Securit
Generalization of Steane’s enlargement construction of quantum codes and applications
No full textWe generalize Steane’s enlargement construction of binary quantum codes to q-ary quantum codes. We then apply this result to BCH codes and the study of asymptotic bounds, and obtain improvements to the quantum BCH codes constructed by Aly and Klappenecker and the quantum asymptotic bounds from algebraic geometry codes obtained by Feng, Ling and Xing.Accepted versio
Application of classical Hermitian self-orthogonal MDS codes to quantum MDS codes
No full textIn this paper, we first construct several classes of classical Hermitian self-orthogonal MDS codes. Through these classical codes, we are able to obtain various quantum MDS codes. It turns out that many of our quantum codes are new in the sense that the parameters of our quantum codes cannot be obtained from all previous constructions.Accepted versio
Optimal locally repairable codes of distance 3 and 4 via cyclic codes
No full textLike classical block codes, a locally repairable code also obeys the Singleton-type bound (we call a locally repairable code optimal if it achieves the Singleton-type bound). In the breakthrough work of [16], several classes of optimal locally repairable codes were constructed via subcodes of Reed-Solomon codes. Thus, the lengths of the codes given in [16] are upper bounded by the code alphabet size q. Recently, it was proved through extension of construction in [16] that length of q-ary optimal locally repairable codes can be q + 1 in [8]. Surprisingly, [2] presented a few examples of q-ary optimal locally repairable codes of small distance and locality with code length achieving roughly q2. Very recently, it was further shown in [10] that there exist q-ary optimal locally repairable codes with length bigger than q+1 and distance propotional to n. Thus, it becomes an interesting and challenging problem to construct new families of q-ary optimal locally repairable codes of length bigger than q + 1. In this paper, we construct a class of optimal locally repairable codes of distance 3 and 4 with unbounded length (i.e., length of the codes is independent of the code alphabet size). Our technique is through cyclic codes with particular generator and parity-check polynomials that are carefully chosen
A deep learning-based process monitoring system for toothbrush manufacturing defect characterization
No full textToothbrush manufacturing process is prone to a number of defects concerning the bristle stapling, affecting the amount of scrap parts and rework. State-of-the-art inspection techniques are characterized by low efficiency, unsustainable operator fatigue, resulting in a low detection performance with the consequence of an overall final product low quality and safety issue. To enable an automatic process monitoring this paper presents a machine vision-based inspection system endowed with a deep-learning YOLOv5s-based decision-making for toothbrush bristles defects identification and characterization. The proposed system is made of three modules, respectively the image acquisition module, the image processing module and the intelligent defect classification module. A laboratory scale experimental rig was designed in order to carry out trial aimed at validating the proposed monitoring method. The results of testing demonstrated a high classification accuracy capability and high performances in terms computation time, indicating an excellent suitability for industrial applications
Repairing Algebraic Geometry Codes
No full textMinimum storage regenerating codes have minimum storage of data in each node and therefore are maximal distance separable (for short) codes. Thus, the number of nodes is upper-bounded by 2 b , where ú is the bits of data stored in each node. From both theoretical and practical points of view (see the details in Section 1), it is natural to consider regenerating codes that nearly have minimum storage of data, and meanwhile, the number of nodes is unbounded. One of the candidates for such regenerating codes is an algebraic geometry code. In this paper, we generalize the repairing algorithm of Reed-Solomon codes given by Guruswami and Wotters to algebraic geometry codes and present a repairing algorithm for arbitrary one-point algebraic geometry codes. By applying our repairing algorithm to the one-point algebraic geometry codes based on the Garcia- Stichtenoth tower, one can repair a code of rate 1 - e and length n over F q with bandwidth (n - 1)(1 - τ) log q for any e = 2 (τ-1/2) logq with a real τ ∈ (0, 1/2). In addition, storage in each node for an algebraic geometry code is close to the minimum storage. Due to nice structures of Hermitian curves, repairing of Hermitian codes is also investigated. As a result, we are able to show that algebraic geometry codes are regenerating codes with good parameters
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