Journal articles on the topic 'Long-tail Problem'
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Sunitha, M., and T. Adilakshmi. "Addressing long tail problem in music recommendation systems." International Journal of Computational Systems Engineering 6, no. 5 (2021): 246. http://dx.doi.org/10.1504/ijcsyse.2021.10045577.
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Sunitha, M., and T. Adilakshmi. "Addressing long tail problem in music recommendation systems." International Journal of Computational Systems Engineering 6, no. 5 (2021): 246. http://dx.doi.org/10.1504/ijcsyse.2021.121367.
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Alshammari, Gharbi, Jose L. Jorro-Aragoneses, Nikolaos Polatidis, Stelios Kapetanakis, Elias Pimenidis, and Miltos Petridis. "A switching multi-level method for the long tail recommendation problem." Journal of Intelligent & Fuzzy Systems 37, no. 6 (December 23, 2019): 7189–98. http://dx.doi.org/10.3233/jifs-179331.
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Chavez, G., C. Proescholdt, and G. Lavy-Shahaf. "The Long Tail Problem: Novel Parametric Methods Still Underestimate Conditional Long-Term Survival In Glioblastoma." International Journal of Radiation Oncology*Biology*Physics 108, no. 3 (November 2020): e783-e784. http://dx.doi.org/10.1016/j.ijrobp.2020.07.247.
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Shiba, Hayato, and Nobuyasu Ito. "Long-Time Tail Problem and Anomalous Transport in Three-Dimensional Nonlinear Lattices." Progress of Theoretical Physics Supplement 178 (2009): 79–85. http://dx.doi.org/10.1143/ptps.178.79.
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Yoon-Joo Park. "The Adaptive Clustering Method for the Long Tail Problem of Recommender Systems." IEEE Transactions on Knowledge and Data Engineering 25, no. 8 (August 2013): 1904–15. http://dx.doi.org/10.1109/tkde.2012.119.
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Zhao, Yan, Weicong Chen, Xu Tan, Kai Huang, and Jihong Zhu. "Adaptive Logit Adjustment Loss for Long-Tailed Visual Recognition." Proceedings of the AAAI Conference on Artificial Intelligence 36, no. 3 (June 28, 2022): 3472–80. http://dx.doi.org/10.1609/aaai.v36i3.20258.
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Data in the real world tends to exhibit a long-tailed label distribution, which poses great challenges for the training of neural networks in visual recognition. Existing methods tackle this problem mainly from the perspective of data quantity, i.e., the number of samples in each class. To be specific, they pay more attention to tail classes, like applying larger adjustments to the logit. However, in the training process, the quantity and difficulty of data are two intertwined and equally crucial problems. For some tail classes, the features of their instances are distinct and discriminative, which can also bring satisfactory accuracy; for some head classes, although with sufficient samples, the high semantic similarity with other classes and lack of discriminative features will bring bad accuracy. Based on these observations, we propose Adaptive Logit Adjustment Loss (ALA Loss) to apply an adaptive adjusting term to the logit. The adaptive adjusting term is composed of two complementary factors: 1) quantity factor, which pays more attention to tail classes, and 2) difficulty factor, which adaptively pays more attention to hard instances in the training process. The difficulty factor can alleviate the over-optimization on tail yet easy instances and under-optimization on head yet hard instances. The synergy of the two factors can not only advance the performance on tail classes even further, but also promote the accuracy on head classes. Unlike previous logit adjusting methods that only concerned about data quantity, ALA Loss tackles the long-tailed problem from a more comprehensive, fine-grained and adaptive perspective. Extensive experimental results show that our method achieves the state-of-the-art performance on challenging recognition benchmarks, including ImageNet-LT, iNaturalist 2018, and Places-LT.
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Zhang, Ziqi, and Lei Luo. "Hate speech detection: A solved problem? The challenging case of long tail on Twitter." Semantic Web 10, no. 5 (September 26, 2019): 925–45. http://dx.doi.org/10.3233/sw-180338.
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Politi, A., and T. Schneider. "Corrections to the Lifshitz Tail and the Long-Time Behaviour of the Trapping Problem." Europhysics Letters (EPL) 5, no. 8 (April 15, 1988): 715–20. http://dx.doi.org/10.1209/0295-5075/5/8/009.
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Fan, Xinyue, Teng Liu, Hong Bao, Weiguo Pan, Tianjiao Liang, and Han Li. "Long-Tail Instance Segmentation Based on Memory Bank and Confidence Calibration." Applied Sciences 12, no. 18 (September 19, 2022): 9366. http://dx.doi.org/10.3390/app12189366.
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In the field of computer vision, training a well-performing model on a dataset with a long-tail distribution is a challenging task. To address this challenge, image resampling is usually introduced as a simple and effective solution. However, when performing instance segmentation tasks, there may be multiple classes in one image. Hence, image resampling alone is not enough to obtain a sufficiently balanced distribution at the level of target data volume. In this paper, we propose an improved instance segmentation method for long-tail datasets based on Mask R-CNN. Specifically, an object-centric memory bank is used to establish an object-centric storage strategy that can solve the imbalance problem with respect to categories. In the testing phase, a post-processing calibration is used to adjust each class logit to change the confidence score, which improves the prediction score of tail classes. A discrete cosine transform-based mask is used to obtain high-quality masks, which improves segmentation accuracy. The evaluation of the proposed method on the LVIS dataset demonstrates its effectiveness. The proposed method improves the AP performance of EQL by 2.2%.
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Oberst, P., D. A. Sandercock, P. Di Giminiani, S. A. Edwards, and P. J. Brunton. "The effect of tail docking in neonatal pigs on the central expression of genes involved in modulating anxiety-like behaviour." Scandinavian Journal of Pain 8, no. 1 (July 1, 2015): 53. http://dx.doi.org/10.1016/j.sjpain.2015.04.020.
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Abstract Background Adverse experiences in early life, such as exposure to stress, can have long term detrimental effects on the future physiology and behaviour of the animal. Typically animals exposed to such experiences are more anxious and more reactive to stress in later life. Tail biting is a major problem in modern pig production, both in terms of animal welfare and productivity. Tail docking in early postnatal life is common practice to reduce risk of this problem, but causes pain and may alter pain sensitivity. Aims To investigate whether a significant painful experience in early life (tail docking) alters the expression of genes in the amygdala that are linked to an anxiety-prone phenotype. Methods Eight female piglets (Landrace/Large White × synthetic sireline) were used. Four piglets were tail docked (amputation of approx. 2/3 of the tail) on post-natal day 3 using hot-iron cautery and four sham-docked piglets served as intact controls. On post-natal day 10, pigs were sedated and then euthanized by barbiturate overdose. Brains were removed, the amygdala grossly dissected and frozen on dry ice. 20 μm sections were cut and subsequently processed using in situ hybridisation with radiolabelled probes complementary to corticotropin-releasing hormone receptor-1 (Crhr1) and CRH receptor-2 (Crhr2) mRNA. Results Crhrl mRNA expression was significantly greater in the amygdala of tail-docked piglets compared with the sham-docked animals. There was no significant difference detected in Crhr2 expression in the amygdala between the groups. Conclusion Increased expression of Crhrl in the amygdala is associated with an anxiety-prone phenotype in rats and pigs, thus it is likely that tail docking in early life leads to enhanced anxiety which may have a negative impact on pig welfare. Ongoing experiments will determine whether these central changes in gene expression are long-lasting. [Support: BBSRC/DEFRA, part of ANIWHA ERA-NET initiative].
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Coutino, Aaron, and Marek Stastna. "The fully nonlinear stratified geostrophic adjustment problem." Nonlinear Processes in Geophysics 24, no. 1 (January 30, 2017): 61–75. http://dx.doi.org/10.5194/npg-24-61-2017.
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Abstract. The study of the adjustment to equilibrium by a stratified fluid in a rotating reference frame is a classical problem in geophysical fluid dynamics. We consider the fully nonlinear, stratified adjustment problem from a numerical point of view. We present results of smoothed dam break simulations based on experiments in the published literature, with a focus on both the wave trains that propagate away from the nascent geostrophic state and the geostrophic state itself. We demonstrate that for Rossby numbers in excess of roughly 2 the wave train cannot be interpreted in terms of linear theory. This wave train consists of a leading solitary-like packet and a trailing tail of dispersive waves. However, it is found that the leading wave packet never completely separates from the trailing tail. Somewhat surprisingly, the inertial oscillations associated with the geostrophic state exhibit evidence of nonlinearity even when the Rossby number falls below 1. We vary the width of the initial disturbance and the rotation rate so as to keep the Rossby number fixed, and find that while the qualitative response remains consistent, the Froude number varies, and these variations are manifested in the form of the emanating wave train. For wider initial disturbances we find clear evidence of a wave train that initially propagates toward the near wall, reflects, and propagates away from the geostrophic state behind the leading wave train. We compare kinetic energy inside and outside of the geostrophic state, finding that for long times a Rossby number of around one-quarter yields an equal split between the two, with lower (higher) Rossby numbers yielding more energy in the geostrophic state (wave train). Finally we compare the energetics of the geostrophic state as the Rossby number varies, finding long-lived inertial oscillations in the majority of the cases and a general agreement with the past literature that employed either hydrostatic, shallow-water equation-based theory or stratified Navier–Stokes equations with a linear stratification.
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Grosof, Isaac, Kunhe Yang, Ziv Scully, and Mor Harchol-Balter. "Nudge: Stochastically Improving upon FCFS." Proceedings of the ACM on Measurement and Analysis of Computing Systems 5, no. 2 (June 2021): 1–29. http://dx.doi.org/10.1145/3460088.
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The First-Come First-Served (FCFS) scheduling policy is the most popular scheduling algorithm used in practice. Furthermore, its usage is theoretically validated: for light-tailed job size distributions, FCFS has weakly optimal asymptotic tail of response time. But what if we don't just care about the asymptotic tail? What if we also care about the 99th percentile of response time, or the fraction of jobs that complete in under one second? Is FCFS still best? Outside of the asymptotic regime, only loose bounds on the tail of FCFS are known, and optimality is completely open. In this paper, we introduce a new policy, Nudge, which is the first policy to provably stochastically improve upon FCFS. We prove that Nudge simultaneously improves upon FCFS at every point along the tail, for light-tailed job size distributions. As a result, Nudge outperforms FCFS for every moment and every percentile of response time. Moreover, Nudge provides a multiplicative improvement over FCFS in the asymptotic tail. This resolves a long-standing open problem by showing that, counter to previous conjecture, FCFS is not strongly asymptotically optimal.
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Li, Ke Feng, and Tian Hui Xia. "The Application of Advanced Composite Material in Tail Driver Shaft of the Helicopter." Applied Mechanics and Materials 86 (August 2011): 365–69. http://dx.doi.org/10.4028/www.scientific.net/amm.86.365.
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The helicopter tail drive shafts are designed by using aluminum alloy conventionally. The composite materials have the advantages of high strength ratio, good fatigue and erosion resistance. It can reduce weight 10%~30% than metal, and improve the pneumatic elasticity characteristics and flight performances of helicopter. This cannot be realized by using other materials. The design of the tail driver shaft has used composite material, so the advantages of light weight, good dynamic performances, high reliability, long life, excellent survivability can be achieved, and critical speed are increased. Torsional vibration problem of helicopter is also solved.
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R, Jayashree. "Recommended System for Enhancing Tag Popularity in a Question Answering Community through Splay-net Techniques." International Journal of Engineering and Advanced Technology 10, no. 2 (December 30, 2020): 43–48. http://dx.doi.org/10.35940/ijeat.b2005.1210220.
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Collaborative filtering filters information by using the recommendations of peer participants. The long tail problem states users with higher points obtain a high reputation compared to less scored users. In popular community question answering websites, like stack exchange network sites, users with unanswered or ignored questions for a long time get a tumbleweed badge without considering their past history. This deteriorates their further contribution to the website. Mostly new or low-reputation people ask the tumbleweed questions. The popularity of the tags follows a long tail theory. The focus of this research work is to design a recommendation system that prevents participants from tumbleweed badge with tag suggestion method to add new or non-popular tags to the existing popular tag list. The splay-net has a self-balancing graph which brings the recently accessed item to the top of the tree. In this paper, we use the splay-net technique to represent users’ reputation along with their tags.
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Mokritskii, Boris Y., Dmitriy A. Pustovalov, A. Stupin, Alexey Anatolevich Vereschaka, A. G. Serebrennikova, and Victorya V. Altukhova. "Selection and Analysis of Parameters for Composite Carbide End Mills." Applied Mechanics and Materials 703 (December 2014): 131–36. http://dx.doi.org/10.4028/www.scientific.net/amm.703.131.
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Carbide end mills are quite expensive tools. Reduction of cost of such end mills while maintaining their key performance characteristics is an important and long-running task. One way for solution of this problem is to develop a composite end mill, which tail part is made of structural material and working part of carbide. Versions for positioning and connecting tail and working parts may differ, and this will influence the performance characteristics and, accordingly, the scope of application of a particular version of end mill. This work was supported by grants No2014 / 68 (Project 254) and No9.251.2014 / K (Project Code 251), Ministry of Education of the Russian Federation.
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Grosof, Isaac, Kunhe Yang, Ziv Scully, and Mor Harchol-Balter. "Nudge: Stochastically Improving upon FCFS." ACM SIGMETRICS Performance Evaluation Review 49, no. 1 (June 22, 2022): 11–12. http://dx.doi.org/10.1145/3543516.3460102.
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The First-Come First-Served (FCFS) scheduling policy is the most popular scheduling algorithm used in practice. Furthermore, its usage is theoretically validated: for light-tailed job size distributions, FCFS has weakly optimal asymptotic tail of response time. But what if we don't just care about the asymptotic tail? What if we also care about the 99th percentile of response time, or the fraction of jobs that complete in under one second? Is FCFS still best? Outside of the asymptotic regime, only loose bounds on the tail of FCFS are known, and optimality is completely open. In this paper, we introduce a new policy, Nudge, which is the first policy to provably stochastically improve upon FCFS. We prove that Nudge simultaneously improves upon FCFS at every point along the tail, for light-tailed job size distributions. As a result, Nudge outperforms FCFS for every moment and every percentile of response time. Moreover, Nudge provides a multiplicative improvement over FCFS in the asymptotic tail. This resolves a long-standing open problem by showing that, counter to previous conjecture, FCFS is not strongly asymptotically optimal. This paper represents an abridged version of [2].
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Chen, Kai, Twan van Laarhoven, and Elena Marchiori. "Gaussian processes with skewed Laplace spectral mixture kernels for long-term forecasting." Machine Learning 110, no. 8 (July 12, 2021): 2213–38. http://dx.doi.org/10.1007/s10994-021-06031-5.
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AbstractLong-term forecasting involves predicting a horizon that is far ahead of the last observation. It is a problem of high practical relevance, for instance for companies in order to decide upon expensive long-term investments. Despite the recent progress and success of Gaussian processes (GPs) based on spectral mixture kernels, long-term forecasting remains a challenging problem for these kernels because they decay exponentially at large horizons. This is mainly due to their use of a mixture of Gaussians to model spectral densities. Characteristics of the signal important for long-term forecasting can be unravelled by investigating the distribution of the Fourier coefficients of (the training part of) the signal, which is non-smooth, heavy-tailed, sparse, and skewed. The heavy tail and skewness characteristics of such distributions in the spectral domain allow to capture long-range covariance of the signal in the time domain. Motivated by these observations, we propose to model spectral densities using a skewed Laplace spectral mixture (SLSM) due to the skewness of its peaks, sparsity, non-smoothness, and heavy tail characteristics. By applying the inverse Fourier Transform to this spectral density we obtain a new GP kernel for long-term forecasting. In addition, we adapt the lottery ticket method, originally developed to prune weights of a neural network, to GPs in order to automatically select the number of kernel components. Results of extensive experiments, including a multivariate time series, show the beneficial effect of the proposed SLSM kernel for long-term extrapolation and robustness to the choice of the number of mixture components.
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Jacka, Saul. "Markov Chains Conditioned Never to Wait Too Long at the Origin." Journal of Applied Probability 46, no. 3 (September 2009): 812–26. http://dx.doi.org/10.1239/jap/1253279853.
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Motivated by Feller's coin-tossing problem, we consider the problem of conditioning an irreducible Markov chain never to wait too long at 0. Denoting by τ the first time that the chain, X, waits for at least one unit of time at the origin, we consider conditioning the chain on the event (τ›T). We show that there is a weak limit as T→∞ in the cases where either the state space is finite or X is transient. We give sufficient conditions for the existence of a weak limit in other cases and show that we have vague convergence to a defective limit if the time to hit zero has a lighter tail than τ and τ is subexponential.
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Jacka, Saul. "Markov Chains Conditioned Never to Wait Too Long at the Origin." Journal of Applied Probability 46, no. 03 (September 2009): 812–26. http://dx.doi.org/10.1017/s0021900200005891.
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Motivated by Feller's coin-tossing problem, we consider the problem of conditioning an irreducible Markov chain never to wait too long at 0. Denoting by τ the first time that the chain,X, waits for at least one unit of time at the origin, we consider conditioning the chain on the event (τ›T). We show that there is a weak limit asT→∞ in the cases where either the state space is finite orXis transient. We give sufficient conditions for the existence of a weak limit in other cases and show that we have vague convergence to a defective limit if the time to hit zero has a lighter tail than τ and τ is subexponential.
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Riegel, Ulrich. "A QUANTITATIVE STUDY OF CHAIN LADDER BASED PRICING APPROACHES FOR LONG-TAIL QUOTA SHARES." ASTIN Bulletin 45, no. 2 (March 24, 2015): 267–307. http://dx.doi.org/10.1017/asb.2015.2.
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AbstractPricing approaches for long-tail quota shares are often based on the chain ladder method. Apart from IBNR calculation, common pricing methods require volume measures for accident years in the observation period, and for the quotation period. In practice, in most cases restated premiums are used as the volume measures. The prediction error of the chain ladder method is an important part of the prediction uncertainty of these pricing approaches. There are, however, two sources of uncertainty that are not addressed by the chain ladder model: the stochastic volatility of the claims in the first development year; and the restatement uncertainty, the risk that the restated premium is not a good volume measure. We extend Mack's chain ladder model to cover these two sources of uncertainty, and calculate the mean-squared error of chain ladder pricing approaches with arbitrary weights for the accident years in the observation period. Then we focus on the problem of finding optimal weights for the accident years. First, we assume that the parameters for restatement uncertainty are given, and provide recursion formulas to calculate approximately-optimal weights. Second, we describe a maximum likelihood approach that can be used to estimate the restatement uncertainty.
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Heim, Steve W., Mostafa Ajallooeian, Peter Eckert, Massimo Vespignani, and Auke Jan Ijspeert. "On designing an active tail for legged robots: simplifying control via decoupling of control objectives." Industrial Robot: An International Journal 43, no. 3 (May 16, 2016): 338–46. http://dx.doi.org/10.1108/ir-10-2015-0190.
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Purpose The purpose of this paper is to explore the possible roles of active tails for steady-state legged locomotion, focusing on a design principle which simplifies control by decoupling different control objectives. Design/methodology/approach A series of simple models are proposed which capture the dynamics of an idealized running system with an active tail. These models suggest that the overall control problem can be simplified and effectively decoupled via a proper tail design. This design principle is further explored in simulation using trajectory optimization. The results are then validated in hardware using a one degree-of-freedom active tail mounted on the quadruped robot Cheetah-Cub. Findings The results of this paper show that an active tail can greatly improve both forward velocity and reduce body-pitch per stride while adding minimal complexity. Further, the results validate the design principle of using long, light tails compared to shorter heavier ones. Originality/value This paper builds on previous results, with a new focus on steady-state locomotion and in particular deals directly with stance phase dynamics. A novel design principle for tails is proposed and validated.
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Scollo, Annalisa, Mustansar Abbas, Barbara Contiero, and Flaviana Gottardo. "Undocked Tails, Mycoplasma-like Lesions and Gastric Ulcers in Slaughtering Pigs: What Connection?" Animals 13, no. 2 (January 15, 2023): 305. http://dx.doi.org/10.3390/ani13020305.
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Tail biting is an economical and behavioral problem in the pork production system worldwide and systematic tail docking has been applied for decades to decrease the risk of its onset. However, legal and market-driven requirements are leading pig producers to rear undocked animals. The aim of this work was to monitor tail, pluck (lungs, pleurae, and liver), stomach, carcass, and thigh lesions in slaughtering pigs belonging to either docked or undocked batches. A total of 525 batches were evaluated at slaughter: 442 docked and 83 undocked batches. The presence of tail lesions was only recorded in undocked batches (44.0 ± 0.402 vs. 0.2 ± 0.2% compared to docked ones, p < 0.001), with a prevalence of severe chronic lesions of 27.3% ± 0.032, suggesting that more and alternative wide efforts to manage long-tailed animals are needed. On the contrary, docked animals showed more frequent ear lesions (9.6% ± 0.037 vs. 4.6% ± 0.019; p = 0.0001). Severe lung lesions were found more frequently in undocked animals (9.2% ± 0.043 vs. 6.6% ± 0.011, p = 0.006), as well as gastric ulcers (26.1% ± 0.021 vs. 20.3% ± 0.37, p = 0.006). These lesions might share the same predisposing factors of tail lesions; the latter might be investigated as an iceberg indicator for other pathological conditions in undocked pigs and eventual causal association among lesions in these organs should be explored.
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Sun, HongGuang, Wen Chen, and K. Y. Sze. "A semi-discrete finite element method for a class of time-fractional diffusion equations." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 1990 (May 13, 2013): 20120268. http://dx.doi.org/10.1098/rsta.2012.0268.
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As fractional diffusion equations can describe the early breakthrough and the heavy-tail decay features observed in anomalous transport of contaminants in groundwater and porous soil, they have been commonly used in the related mathematical descriptions. These models usually involve long-time-range computation, which is a critical obstacle for their application; improvement of computational efficiency is of great significance. In this paper, a semi-discrete method is presented for solving a class of time-fractional diffusion equations that overcome the critical long-time-range computation problem. In the procedure, the spatial domain is discretized by the finite element method, which reduces the fractional diffusion equations to approximate fractional relaxation equations. As analytical solutions exist for the latter equations, the burden arising from long-time-range computation can effectively be minimized. To illustrate its efficiency and simplicity, four examples are presented. In addition, the method is used to solve the time-fractional advection–diffusion equation characterizing the bromide transport process in a fractured granite aquifer. The prediction closely agrees with the experimental data, and the heavy-tail decay of the anomalous transport process is well represented.
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Zemach, Tamar, and Marius Ungarish. "On axisymmetric intrusive gravity currents: the approach to self-similarity solutions of the shallow-water equations in a linearly stratified ambient." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 463, no. 2085 (June 26, 2007): 2165–83. http://dx.doi.org/10.1098/rspa.2007.1868.
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The axisymmetric intrusion of a fixed volume of fluid, which is released from rest and then propagates radially at the neutral buoyancy level in a deep linearly stratified ambient fluid, is investigated. Attention is focused on the development of self-similar propagation. The shallow-water equations representing the high-Reynolds-number motion are used. For the long-time motion, an analytical similarity solution indicates propagation with t 1/3 , but the shape is peculiar: the intrusion propagates like a ring with a fixed ratio of inner to outer radii; the inner domain contains clear ambient fluid. To verify the similarity analytical prediction, a long-time finite-difference solution with realistic initial conditions was performed. To avoid accumulation of numerical errors, the problem was reformulated in terms of new variables. It is shown that the numerical solution has a ‘tail-ring’ shape. The ‘tail’ decays like t −2 and the ‘ring’ tends to the analytical similarity prediction. The initial geometry of the lock does not influence this result. Comparison with the non-stratified case is also presented. It was found that for the non-stratified case, there is a stage of propagation in which the intrusion has a similar ‘tail-ring’ form; however, this stage is only a transient to a self-similar shape which is different from that obtained for the stratified ambient.
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Li, Xin, Lianting Hu, Peixin Lu, Tianhui Huang, Wei Yang, Quan Lu, Huiying Liang, and Long Lu. "A Novel Approach of Feature Space Reconstruction with Three-Way Decisions for Long-Tailed Text Classification." Computational Intelligence and Neuroscience 2022 (April 16, 2022): 1–11. http://dx.doi.org/10.1155/2022/3183469.
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Text classification is widely studied by researchers in the natural language processing field. However, real-world text data often follow a long-tailed distribution as the frequency of each class is typically different. The performance of current mainstream learning algorithms in text classification suffers when the training data are highly imbalanced. The problem can get worse when the categories with fewer data are severely undersampled to the extent that the variation within each category is not fully captured by the given data. At present, there are a few studies on long-tailed text classification which put forward effective solutions. Encouraged by the progress of handling long-tailed data in the field of image, we try to integrate effective ideas into the field of long-tailed text classification and prove the effectiveness. In this paper, we come up with a novel approach of feature space reconstruction with the help of three-way decisions (3WDs) for long-tailed text classification. In detail, we verify the rationality of using a 3WD model for feature selection in long-tailed text data classification, propose a new feature space reconstruction method for long-tailed text data for the first time, and demonstrate how to effectively generate new samples for tail classes in reconstructed feature space. By adding new samples, we enrich the representing information of tail classes, to improve the classification results of long-tailed text classification. After some comparative experiments, we have verified that our model is an effective strategy to improve the performance of long-tailed text classification.
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Abdulkareem, Ahmed B. "Transmission Control Protocol Analysis Using NS3." Ingénierie des systèmes d information 27, no. 1 (February 28, 2022): 135–41. http://dx.doi.org/10.18280/isi.270116.
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The NS-3 Test Framework provides a focus on multidisciplinary development and high-level design, and is now being used by various experts around the world. Surprisingly, its Data Collection Protocol (DCP) implementation is late and is not planned to be used as a reference point for Transmission Control Protocol (TCP), focused research, where the Herald has provided NS-3 to accept NS-2 submissions. The latest-best configuration consists of a number of PCs connected to each other by two sweets and switches. As a result of the overlapping character, being a significant number of PCs, channels can create a complex problem. If a case of sensitivity is sent to the TCP bundles, each word flow should be taken with the appropriate treatment when there is a deadline. Drop-tail is a common scheme for using the power of measurement, and with this provision, the feeling cannot be limited to the illumination of long lines, which increases the delay in these methods. As a result, the flow efficiency decreases. The Board Active Queue Management (AQM) is largely oblivious to the fact that conspiracy and sensitivity are not the basic mechanisms that must be considered in solving this major problem. Another area to look for is depression, and the range of serious problems. In this work, a framework was developed based on drop- tail and different active queue management schemes such as DLP, Drop-Tail delivers, Packet First in First Out (PFIFO), Random Early Detection (RED) and Code Exploration Introduction. The evaluation is performed using an open-framework framework (NS-3) assessment framework. In the end, the results of the review suggest that Code and RED, a unique line of management figures, have shown much needed performance.
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Rival, David E., Wenchao Yang, and Jean-Bernard Caron. "Fish without Tail Fins—Exploring the Function of Tail Morphology of the First Vertebrates." Integrative and Comparative Biology 61, no. 1 (February 26, 2021): 37–49. http://dx.doi.org/10.1093/icb/icab004.
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Synopsis We use a series of hydrodynamic experiments on abstracted models to explore whether primitive vertebrates may have swum under various conditions without a clearly-differentiated tail fin. Cambrian vertebrates had post-anal stubby tails, some had single dorsal and ventral fins, but none had yet evolved a clearly differentiated caudal fin typical of post-Cambrian fishes, and must have relied on their long and flexible laterally-compressed bodies for locomotion, i.e., by bending their bodies side-to-side in order to propagate waves from head to tail. We approach this problem experimentally based on an abstracted model of Metaspriggina walcotti from the 506-million-year old Burgess Shale by using oscillating thin flexible plates while varying the tail fin geometry from rectangular to uniform, and finally to a no tail–fin condition. Despite a missing tail fin, this study supports the observation that the abstracted Metaspriggina model can generate a strong propulsive force in cruise conditions, both away from, and near the sea bed (in ground effect). However, when the abstracted Metaspriggina model moves in ground effect, a weaker performance is observed, indicating that Metaspriggina may not necessarily have been optimized for swimming near the sea bed. When considering acceleration from rest, we find that the Metaspriggina model's performance is not significantly different from other morphological models (abstracted truncate tail and abstracted heterocercal tail). Statistical analysis shows that morphological parameters, swimming modes, and ground effect all play significant roles in thrust performance. While the exact relationships of Cambrian vertebrates are still debated, as agnathans, they share some general characteristics with modern cyclostomes, in particular an elongate body akin to lampreys. Lampreys, as anguilliform swimmers, are considered to be some of the most efficient swimmers using a particular type of suction thrust induced by the traveling body wave as it travels from head to tail. Our current experiments suggest that Metaspriggina’s ability in acceleration from rest, through possibly a similar type of suction thrust, which is defined as the ability to generate low pressure on upstream facing sections of the body, might have evolved early in response to increasing predator pressure during the Cambrian Explosion.
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Liu, Zhiqiang, Haifeng Jiang, and Minmin Yuan. "Study on Application of TiO2 Photocatalytic Materials in Purification of Highway Tunnel Tail Gas." E3S Web of Conferences 233 (2021): 01073. http://dx.doi.org/10.1051/e3sconf/202123301073.
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In recent years, with the continuous expansion of the scale of highway tunnels in China, the problem of tail gas pollution in highway tunnels has become increasingly prominent. The tunnel is a long and narrow space, which makes air pollutants easy to accumulate and difficult to diffuse. In this paper, the present situation and application scenarios of TiO2 photocatalytic materials in the purification technology of highway tunnel exhaust gas are studied and analyzed, and the nano TiO2 photocatalytic materials which can be applied to highway tunnels, corresponding highway stations and their affiliated facilities are put forward, so as to greatly degrade automobile exhaust gas, atmospheric chemical pollution and environmental biological pollution.
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Mackenzie, Joel M. "Managing tail latency in large scale information retrieval systems." ACM SIGIR Forum 54, no. 1 (June 2020): 1–2. http://dx.doi.org/10.1145/3451964.3451982.
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As both the availability of internet access and the prominence of smart devices continue to increase, data is being generated at a rate faster than ever before. This massive increase in data production comes with many challenges, including efficiency concerns for the storage and retrieval of such large-scale data. However, users have grown to expect the sub-second response times that are common in most modern search engines, creating a problem --- how can such large amounts of data continue to be served efficiently enough to satisfy end users? This dissertation investigates several issues regarding tail latency in large-scale information retrieval systems. Tail latency corresponds to the high percentile latency that is observed from a system --- in the case of search, this latency typically corresponds to how long it takes for a query to be processed. In particular, keeping tail latency as low as possible translates to a good experience for all users, as tail latency is directly related to the worst-case latency and hence, the worst possible user experience. The key idea in targeting tail latency is to move from questions such as "what is the median latency of our search engine?" to questions which more accurately capture user experience such as "how many queries take more than 200 ms to return answers?" or "what is the worst case latency that a user may be subject to, and how often might it occur?" While various strategies exist for efficiently processing queries over large textual corpora, prior research has focused almost entirely on improvements to the average processing time or cost of search systems. As a first contribution, we examine some state-of-the-art retrieval algorithms for two popular index organizations, and discuss the trade-offs between them, paying special attention to the notion of tail latency. This research uncovers a number of observations that are subsequently leveraged for improved search efficiency and effectiveness. We then propose and solve a new problem, which involves processing a number of related query variations together, known as multi-queries , to yield higher quality search results. We experiment with a number of algorithmic approaches to efficiently process these multi-queries, and report on the cost, efficiency, and effectiveness trade-offs present with each. Finally, we examine how predictive models can be used to improve the tail latency and end-to-end cost of a commonly used multi-stage retrieval architecture without impacting result effectiveness. By combining ideas from numerous areas of information retrieval, we propose a prediction framework which can be used for training and evaluating several efficiency/effectiveness trade-off parameters, resulting in improved trade-offs between cost, result quality, and tail latency.
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Högel, J., A. C. Rodloff, G. Büchele, and W. Gaus. "Randomized Observational Studies on the Economics of Therapies – Biometrical Experience of Two Trials." Methods of Information in Medicine 37, no. 01 (1998): 53–58. http://dx.doi.org/10.1055/s-0038-1634503.
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Abstract:Economic studies in medicine are intended to investigate costs, associated with a particular problem dealing with the indication, diagnosis or therapy, for instance, whether the high costs involved in a highly intensive or innovative therapy could be balanced by the eventual savings made, due to the shorter periods of treatment. In such situations a randomized controlled trial is necessary to find out which therapy or which therapeutical strategy is least expensive in the long run. Economic studies do, however, present some specific problems. Making a list of all the cost-relevant treatment items can be very laborious, but the use of flat rates and lump sums alone cannot lead to a complete cost analysis. Often, costs between hospitals vary more than between treatment regimens.Early and sudden deaths incur low costs and may bias the results. Furthermore, costs are distributed with a long and heavy upper tail incltJding extreme outliers. This does, in fact, complicate the estimation of the sample size. In this article, these problems are outlined and, with the help ofthe data obtained from two randomized economic trials in health care, solutions are proposed and discussed.
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Tilney, L. G., D. J. DeRosier, and M. S. Tilney. "How Listeria exploits host cell actin to form its own cytoskeleton. I. Formation of a tail and how that tail might be involved in movement." Journal of Cell Biology 118, no. 1 (July 1, 1992): 71–81. http://dx.doi.org/10.1083/jcb.118.1.71.
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After Listeria is phagocytosed by a macrophage, it dissolves the phagosomal membrane and enters the cytoplasm. The Listeria then nucleates actin filaments from its surface. These actin filaments rearrange to form a tail with which the Listeria moves to the macrophage surface as a prelude to spreading. Since individual actin filaments appear to remain in their same positions in the tail in vitro after extraction with detergent, the component filaments must be cross-bridged together. From careful examination of the distribution of actin filaments attached to the surface of Listeria and in the tail, and the fact that during and immediately after division filaments are not nucleated from the new wall formed during septation, we show how a cloud of actin filaments becomes rearranged into a tail simply by the mechanics of growth. From lineage studies we can relate the length of the tail to the age of the surface of Listeria and make predictions as to the ratio of Listeria with varying tail lengths at a particular time after the initial infection. Since we know that division occurs about every 50 min, after 4 h we would predict that if we started with one Listeria in a macrophage, 16 bacteria would be found, two with long tails, two with medium tails, four with tiny tails, and eight with no tails or a ratio of 1:1:2:4. We measured the lengths of the tails on Listeria 4 h after infection in serial sections and confirmed this prediction. By decorating the actin filaments that make up the tail of Listeria with subfragment 1 of myosin we find (a) that the filaments are indeed short (maximally 0.3 microns in length); (b) that the filament length is approximately the same at the tip and the base of the tail; and (c) that the polarity of these filaments is inappropriate for myosin to be responsible or to facilitate movement through the cytoplasm, but the polarity insures that the bacterium will be located at the tip of a pseudopod, a location that is essential for spreading to an adjacent cell. Putting all this information together we can begin to unravel the problem of how the Listeria forms the cytoskeleton and what is the biological purpose of this tail. Two functions are apparent: movement and pseudopod formation.
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YANG, YAN-HONG, MING-XIA LI, WEI-XING ZHOU, and H. EUGENE STANLEY. "NON-POISSON DONATION BEHAVIORS IN VIRTUAL WORLDS." Fractals 27, no. 04 (June 2019): 1950061. http://dx.doi.org/10.1142/s0218348x19500610.
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Similar to charitable giving in real world, donation behaviors play an important role in the complex interactions among individuals in virtual worlds. However, it is not clear if the donation process is random or not. We investigate this problem using detailed data from parallel virtual worlds adhered to a massively multiplayer online role-playing game. We find that the inter-donation durations follow power-law-tailed distributions distributed with an average tail exponent close to 1.91, have strong long-range correlations, and possess multifractal features. These findings indicate that the donation process is non-Poissonian, which has potential worth in modeling the complicated individual behaviors in virtual worlds.
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Zhang, Zhong Miao, Cun Gang Lin, and Shi Ming Wu. "Slurry Shield Tunnelling in Clayey Soils: Typical Problems and Countermeasures." Advanced Materials Research 243-249 (May 2011): 2944–47. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.2944.
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The distinguishing characteristics of clay are high cohesion and low permeability. For slurry shield tunnelling in clayey soils, favorable aspects are that slurry cake with low permeability can be established more easily and effectively at the excavation face thanks to clay’s high cohesion, which is advantageous for stability of excavation face, and long stand-up time of clay offers enough time for backfilling of the tail void before collapse of surrounding soils, thus lessening ground volume loss. However, some typical problems are encountered due to clay’s high cohesion and low permeability. One primary problem is the clogging of slurry pipeline, once in case of which, slurry pressure will fluctuate severely, thus inducing unstable condition at the excavation face. In extreme cases, the pipeline bursts and soils at the excavation face collapse towards the cutterhead for immediate drop of slurry pressure. Another common problem is clay’s adhesion to the cutterhead, which weakens the excavation efficiency of cutterhead and limits advance rate of the shield machine. Tunnelling will inevitably disturb surrounding soils and excess pore water pressure occurs. In clayey soils, due to clay’s low permeability, it usually takes quite a long time for the excess pore water pressure to disperse completely. The consolidation settlements associated with pore water dispersing account for a large percentage of the total settlements. Accumulated ground settlements threaten structures and pipelines nearby. For these problems encountered during slurry shield tunnelling in clayey soils, both preventive and counter measures are put forward in detail in this study. The proposed measures can be used as a reference to avoid, mitigate and deal with problems encountered during slurry shield tunnelling in clayey soils.
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Li, Liuqing. "Cross-Border E-Commerce Intelligent Information Recommendation System Based on Deep Learning." Computational Intelligence and Neuroscience 2022 (February 23, 2022): 1–11. http://dx.doi.org/10.1155/2022/6602471.
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In order to improve the effect of cross-border e-commerce intelligent information recommendation, this paper applies deep learning to the intelligent information processing and intelligent recommendation of e-commerce and proposes an improved version of the topic model to solve the problem of feature extraction of the text of the recommendation system. In order to deal with translation problems, this paper proposes an end-to-end sequence-to-sequence learning method. In addition, this study uses the long tail theory to excavate the mass commodities in the niche and recommends these products to users as suggestions. Finally, this paper proposes a niche product recommendation algorithm based on the graph search strategy based on the graph model. The experiment shows that the cross-border e-commerce intelligent information recommendation system based on deep learning proposed in this paper has a good recommendation effect and meets the recommendation needs of cross-border e-commerce.
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Sherman, Dov, and Ilan Be'ery. "Shape and energies of a dynamically propagating crack under bending." Journal of Materials Research 18, no. 10 (October 2003): 2379–86. http://dx.doi.org/10.1557/jmr.2003.0333.
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We report on the exact shape of a propagating crack in a plate with a high width/thickness ratio and subjected to bending deformation. Fracture tests were carried out with brittle solids—single crystal, polycrystalline, and amorphous. The shape of the propagating crack was determined from direct temporal crack length measurements and from the surface perturbations generated during rapid crack propagation. The shape of the crack profile was shown to be quarter-elliptical with a straight, long tail; the governing parameter of the ellipse axes is the specimen's thickness at most length of crack propagation. Universality of the crack front shape is demonstrated. The continuum mechanics approach applicable to two-dimensional problems was used in this three-dimensional problem to calculate the quasistatic strain energy release rate of the propagating crack using the formulations of the dynamic energy release rate along the crack loci. Knowledge of the crack front shape in the current geometry and loading configuration is important for practical and scientific aspects.
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YANG, TAO, QIANQIAN LI, XINGANG XIA, ERBO ZHAO, GUO LIU, and ZHANGANG HAN. "HOW LONG CAN YOU ENJOY BLACKJACK WITH 100 CHIPS?" International Journal of Modern Physics C 22, no. 10 (October 2011): 1161–71. http://dx.doi.org/10.1142/s0129183111016804.
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Gambling-related research has implications in financial area understandings and applications. Researches in this area usually focus on pathology, risk-taking, decision-making and addiction. Few works have been done to demonstrate the distribution of the playing time before players go bankrupt. One problem is that it is difficult to get statistics in real world gambling. In this paper, we do simulations in a Blackjack game with a selected strategy. We find the distribution of playing time before players lose a certain amount of money as a power law distribution, indicating the existence of very long playing time players. We also find that double is the most important factor that causes the fat tail. Comparison shows that when removing double, split and three to two payoff, Blackjack goes back to a random walk. The increase of the number of decks somewhat decreases the average playing time. Our results may have pathologic gambling intervention implications.
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Szűcs, Bernadett, Edit Nagy, Stefan Talev, Ildikó Garai, and László Galuska. "The role of FDG PET/CT discovering the cause of fever of unknown origin." Orvosi Hetilap 153, no. 6 (February 2012): 227–31. http://dx.doi.org/10.1556/oh.2012.29296.
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The fever of unknown origin from time to time constitutes a serious clinical problem and nearly all diagnostic methods are involved to discover urgently its cause. According to literature data 18F-fluoro-deoxyglucose PET/CT was successful in 25-70% of cases even in patients without any positive findings with conventional diagnostic techniques. The Hungarian National Health Fund does not include fever of unknown origin in the list of reimbursed 18F-fluoro-deoxyglucose PET/CT indications. The authors try to illustrate the clinical problem with this case report. Fever of unknown origin persisted in a patient for a year, but conventional diagnostic procedures were unsuccessful to find the cause of the fever. Finally, 18F-fluoro-deoxyglucose PET/CT indicated a metabolically active focus between the pancreas tail and the spleen. After a long-lasting antibiotic therapy the patient became symptomfree. Orv. Hetil., 2012, 153, 227–231.
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Garcimartín, Angel, Bruno V. Guerrero, Alexandre Nicolas, Rodrigo C. Barbosa da Silva, and Iker Zuriguel. "On the broad tails in breaking time distributions of vibrated clogging arches." EPJ Web of Conferences 249 (2021): 03009. http://dx.doi.org/10.1051/epjconf/202124903009.
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Flowing grains can clog an orifice by developing arches, an undesirable event in many cases. Several strategies have been put forward to avoid this. One of them is to vibrate the system in order to undo the clogging. Nevertheless, the time taken to break an arch under a constant vibration has a distribution displaying a heavy tail. This can lead to a situation where the average breaking time is not well defined. Moreover, it has been observed in some experiments that these tails tend to flatten for very long times, exacerbating the problem. Here we will review two conceptual frameworks that have been proposed to understand the phenomenon and discuss their physical implications.
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VLAD, MARCEL OVIDIU. "LINEAR VERSUS NONLINEAR AMPLIFICATION: A GENERALIZATION OF THE NOVIKOV-MONTROLL-SHLESINGER-WEST CASCADE." International Journal of Modern Physics B 06, no. 03n04 (February 1992): 417–35. http://dx.doi.org/10.1142/s0217979292000220.
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The framework of this paper is the theory of statistical fractals. A general approach for the scale-invariant stochastic amplification is derived. The model is based on the assumption that the amplification coefficients as well as the probability of an amplification event are random variables selected from a certain probability law. Both linear and nonlinear cases are considered. For linear processes a general solution is available. Like in the case of constant amplification factors the probability density of an amplified variable has a long tail. However, the analytical form of the tail is different: it can be expressed as a sum of inverse power laws modulated by oscillatory functions of the logarithm of the amplified variable, having different characteristic periods. In the nonlinear case no general analytic solutions are available. For a mapping with saturation and a single stable fixed point the probability density of the amplified varibale may have a singularity at a fixed point. A situation with amplification and diminution is also considered. In this case the solution has the features of a double statistical fractal. A generalized version of the linear model is applied to the problem of overdispersed molecular clocks.
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Wairagade, S. "COMPARATIVE CLINICAL STUDY OF AMSABASTI AND SNEHAN – SWEDAN THERAPY BY LAGHUVISHGARBHA TAIL ALONG WITH TRAYODASHANGGUGGULU IN AVABAHUKA (FROZEN SHOULDER)." Journal of Medical pharmaceutical and allied sciences 10, no. 3 (July 15, 2021): 3011–15. http://dx.doi.org/10.22270/jmpas.v10i3.1150.
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Avabahuka is caused mainly by vitiated vata. Avabahuka is not mentioned in nanatmajvatavyadhi but acharya sushruta and other acharyas considered avabahuka as vatavyadhi. Avabahuka is a disease that affects amsa sandhi. Avabahuka is correlated with frozen shoulder of modern science. It is also known as adhesive capsulitis, or stiff shoulder where joint pain and stiffness of shoulder joint both occur. Therefore as avabahuka causes major limitations in activities of daily living casting a negative influence on the quality of life as well as long-term or even permanent disability in a few of the patients, proper treatment is needed for the problem. In ayurveda basic principle of avabahuka treatment is vata shaman chikitsa. The general line of treatment for vatavyadhi issnehana, swedana, mrudusamshodhan, basti, nasya, and so on. Snehana – swedana for the treatment of avabahuka which is generally given in vatavyadhichikitsa has gained popularity for its efficacy. Evaluation of the utility, safety, and efficacy of laghuvishagarbha tail amsabasti by amsabasti yantra along with trayodashangguggulu as compare to laghuvishagarbha tail snehana – swedana along with trayodashangguggulu in the management of avbahuka (frozen shoulder). In this study, 140 patients will be divided randomly into 2 groups (70 in each). In group a (experimental) –amsabasti of laghuvishgarbha tail and oral drug trayodashangguggulu (500 mg thrice a day) after meals with plain water will be given for 21 days and group b (control) –snehana of laghuvishgarbha tail, swedana of by plain water and oral drug trayodashangguggulu (500 mg thrice a day) after meals with plain water will be given for 21 days. Assessment of avabahuka will be recorded on day 0, on 7th day, on 14th day and on 21st day. Changes will be observed in objective outcomes. Amsa basti will be more efficacious thansnehana -swedana in the management of avabahuka.
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Xin, Hongbo, Yujie Wang, Xianzhong Gao, Qingyang Chen, Bingjie Zhu, Jianfeng Wang, and Zhongxi Hou. "Modeling and control of a quadrotor tail-sitter unmanned aerial vehicles." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 236, no. 3 (October 6, 2021): 443–57. http://dx.doi.org/10.1177/09596518211050466.
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The tail-sitter unmanned aerial vehicles have the advantages of multi-rotors and fixed-wing aircrafts, such as vertical takeoff and landing, long endurance and high-speed cruise. These make the tail-sitter unmanned aerial vehicle capable for special tasks in complex environments. In this article, we present the modeling and the control system design for a quadrotor tail-sitter unmanned aerial vehicle whose main structure consists of a traditional quadrotor with four wings fixed on the four rotor arms. The key point of the control system is the transition process between hover flight mode and level flight mode. However, the normal Euler angle representation cannot tackle both of the hover and level flight modes because of the singularity when pitch angle tends to [Formula: see text]. The dual-Euler method using two Euler-angle representations in two body-fixed coordinate frames is presented to couple with this problem, which gives continuous attitude representation throughout the whole flight envelope. The control system is divided into hover and level controllers to adapt to the two different flight modes. The nonlinear dynamic inverse method is employed to realize fuselage rotation and attitude stabilization. In guidance control, the vector field method is used in level flight guidance logic, and the quadrotor guidance method is used in hover flight mode. The framework of the whole system is established by MATLAB and Simulink, and the effectiveness of the guidance and control algorithms are verified by simulation. Finally, the flight test of the prototype shows the feasibility of the whole system.
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Pijoh, Deyv, Dewi Apri Astuti, Sri Supraptini Mansjoer, Dondin Sajuthi, and Irma Herawati Suparto. "KAJIAN TINGKAH LAKU MONYET EKOR PANJANG (Macaca Fascicularis) OBES DALAM KANDANG INDIVIDU." ZOOTEC 40, no. 2 (July 31, 2020): 781. http://dx.doi.org/10.35792/zot.40.2.2020.30455.
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STUDY ON BEHAVIOUR OF THE LONG TAIL MONKEY (Macaca fascicularis) OBESE IN INDIVIDUAL CAGE. This study was designed to obtain information of development behaviour the obesity of long-tailed monkey (Macaca fascicularis) fed with high energy obes diet. The need of obese monkeys highly to model byomedis obesity. Obesity is now a universal problem that needs to be explored and studied. Therefore, the objective of this research was to develop obese adult male monkeys with high energy food for 12 months and monitoring their behaviour. Fifteen adult male monkeys 6-8 years old with the weight of between 4-5 kg were divided equally into three groups. The first group was body weight average 4.50 kg, the second group was body weight average 5.00 kg; and the third group was body weight average 4.75 kg. The results showed that body weight gave a significant effect (P <0.01) on daily behaviour and also gave a significant effect (P<0.01) on fed behaviour frequently,drink behaviour, agonistic behaviour, grooming behaviour, and locomotion behaviour .Keywords: Behaviour frequently, Long-tailed monkey (Macaca fascicularis), Obesity)
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Abildgren, Kim. "Tail events in the FX markets since 1740." Journal of Risk Finance 15, no. 3 (May 19, 2014): 294–311. http://dx.doi.org/10.1108/jrf-04-2014-0041.
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Purpose – The purpose of this paper is to explore the extent of the so-called “small-sample problem” within quantitative exchange-rate risk management. Design/methodology/approach – The authors take a closer look at the frequency distribution of nominal price changes in the European foreign exchange markets. Findings – The analysis clearly illustrates the risk of seriously underestimating the probability and magnitude of tail events when frequency distributions are derived from fairly short data samples. Practical implications – The authors suggest that financial institutions and regulators should have an eye for the long-term historical perspective when designing sensitivity tests or “worst case” scenarios in relation to risk assessments and stress tests. Originality/value – The authors add to the literature by analysing the distribution of nominal exchange-rate fluctuations on the basis of a unique quarterly data set for ten European exchange-rate pairs covering a time span of 273 years constructed by the authors. To the best of the authors' knowledge this is the first study on nominal exchange-rate changes for a large number of exchange-rate pairs based on quarterly data spanning almost three centuries.
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Chen, Yantong, Zhongling Zhang, Zekun Chen, Yanyan Zhang, and Junsheng Wang. "Fine-Grained Classification of Optical Remote Sensing Ship Images Based on Deep Convolution Neural Network." Remote Sensing 14, no. 18 (September 13, 2022): 4566. http://dx.doi.org/10.3390/rs14184566.
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Marine activities occupy an important position in human society. The accurate classification of ships is an effective monitoring method. However, traditional image classification has the problem of low classification accuracy, and the corresponding ship dataset also has the problem of long-tail distribution. Aimed at solving these problems, this paper proposes a fine-grained classification method of optical remote sensing ship images based on deep convolution neural network. We use three-level images to extract three-level features for classification. The first-level image is the original image as an auxiliary. The specific position of the ship in the original image is located by the gradient-weighted class activation mapping. The target-level image as the second-level image is obtained by threshold processing the class activation map. The third-level image is the midship position image extracted from the target image. Then we add self-calibrated convolutions to the feature extraction network to enrich the output features. Finally, the class imbalance is solved by reweighting the class-balanced loss function. Experimental results show that we can achieve accuracies of 92.81%, 93.54% and 93.97%, respectively, after applying the proposed method on different datasets. Compared with other classification methods, this method has a higher accuracy in optical aerospace remote sensing ship classification.
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Maharani, Septya, Swadika Ibnu Persyadha, Dedy Cahyadi, and Mufadhol Mufadhol. "Weighted Product Method for Selection of Superior Seeds Catfish in the Clarias Gariepinus Types (Sangkuriang)." E3S Web of Conferences 125 (2019): 23008. http://dx.doi.org/10.1051/e3sconf/201912523008.
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Sangkuriang catfish is a famous clarias clan fish form his slick and long body non-scaly, with dorsal fins and a long rear fin, which sometimes merges into the tail fin makes it look like a short eel. Catfish also have additional breathing apparatus in the form of modifications from gill arc. There is a pair of fins that are spines bone that is sharp, on the pectoral fin. Some things to consider in order to select superior seedlings of sangkuriang catfish such as size, weight, color, physical defect, even water conditions, which in reality not all catfish farmers know about it. This decision support system using the Weighted Product (WP) method is one of the methods that use the true value in determining the rating of each alternative on each criterion to determine the conclusion of a problem. Based on the results of testing the Selection Decision Support System of the Superior Broodstock Sangkuriang Catfish has an accuracy rate of 87.5%.
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XUE, B. X., and T. LIU. "INVESTMENT DECISION OF TOURISM LEISURE PROJECT BASED ON COLLABORATIVE FILTERING ALGORITHM." Latin American Applied Research - An international journal 48, no. 4 (October 31, 2018): 293–97. http://dx.doi.org/10.52292/j.laar.2018.243.
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In the era of the Big Bang, users have to spend a lot of time looking for the information they really need, and the search engine can't present information that is not described by the user. Based on the User based collaborative filtering recommendation algorithm and the collaborative filtering recommendation algorithm, this paper proposes User-CF algorithm, User-CF-1 algorithm, Item-CF algorithm, Item-CF-1 algorithm, and finally integrates four algorithms to obtain the cooperative strategy based on collaborative filtering is a hybrid recommendation algorithm, namely the Final algorithm. It has been verified that the Final algorithm can effectively solve the long tail problem in the travel strategy recommendation and greatly increase the coverage of the recommended strategy.
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Xu, Hui, Fengyang Cheng, Yuebao Wang, and Dongya Cheng. "A necessary and sufficient condition for the subexponentiality of the product convolution." Advances in Applied Probability 50, no. 01 (March 2018): 57–73. http://dx.doi.org/10.1017/apr.2018.4.
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Abstract Let X and Y be two independent and nonnegative random variables with corresponding distributions F and G. Denote by H the distribution of the product XY, called the product convolution of F and G. Cline and Samorodnitsky (1994) proposed sufficient conditions for H to be subexponential, given the subexponentiality of F. Relying on a related result of Tang (2008) on the long-tail of the product convolution, we obtain a necessary and sufficient condition for the subexponentiality of H, given that of F. We also study the reverse problem and obtain sufficient conditions for the subexponentiality of F, given that of H. Finally, we apply the obtained results to the asymptotic study of the ruin probability in a discrete-time insurance risk model with stochastic returns.
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Zeng, Wei, Ya Fan, Bao Zhuo Zhou, and Qing Xian Wang. "A Recommendation Algorithm from the Object Perspective." Applied Mechanics and Materials 687-691 (November 2014): 2664–67. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.2664.
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The purpose of designing recommender systems is to help individual users find relevant information. However, many recommender systems have been facing the challenges of finding niche objects, which users may like but difficult to find due to the lack of sufficient data. In this paper, we propose a recommendation algorithm which takes a niche object as input and outputs a list of users who may be interested it. By this approach, every niche object can be recommended at least one time. Further analysis indicates that those niche objects are usually collected by active users and the owners who are very similar to each other. Therefore, this work has outlined the significant relevance with the challenge, the Long Tail problem, and provided a different perspective to solve it in the field of information filtering.
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Yu, Huaidong, and Jian Yin. "Aging Residual Factorization Machines: A Multi-Layer Residual Network Based on Aging Mechanisms." Applied Sciences 12, no. 11 (May 24, 2022): 5318. http://dx.doi.org/10.3390/app12115318.
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With the rapid development of recommendation systems, models and algorithms supporting the core of recommendation systems have emerged one after another, and researchers have attempted to optimize them. However, the structure of these models is complex. Popular deep neural networks often achieve the highest utilization of data by increasing the number of hidden layers, ignoring the problems of exploding and vanishing gradients and even the entire degradation of the networks. However, researchers pay too much attention to algorithms and models and do not consider the dataset itself. Methods for processing data and finding possible connections between the data and models have become new explorable points. Cold start is also a problem that researchers have been trying to solve and optimize since the birth of the recommendation system. Recent studies also provide good ideas for solving cold start, but the problem is that researchers still do not focus on datasets. In order to fill the gap in the exploration and research of datasets, this paper takes the long tail distribution and cold start problems that are common in recommendation systems such as the starting point, combines the residual network in computer vision with deep learning, and proposes the aging mechanism of datasets. In this paper, a multi-layer residual network based on aging mechanisms called Aging Residual Factorization Machines (ARFM) is proposed. Parallel experiments with other model algorithms are carried out on three datasets of different sizes and categories. Experimental results show that ARFM achieve performance advantages under the premise of different recommendation tasks.