42,664 research outputs found
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Acquiring User Strategies and Preferences for Negotiating Agents: A Default Then Adjust Method
No full textA wide range of algorithms have been developed for various types of negotiating agents. In developing such algorithms the main focus has been on their efficiency and their effectiveness. However, this is only a part of the picture. Typically, agents negotiate on behalf of their owners and for this to be effective the agents must be able to adequately represent their owners’ strategies and preferences for negotiation. However, the process by which such knowledge is acquired is typically left unspecified. To address this problem, we undertook a study of how user information about negotiation tradeoff strategies and preferences can be captured. Specifically, we devised a novel default-then-adjust acquisition technique. In this, the system firstly does a structured interview with the user to suggest the attributes that the tradeoff could be made between, then it asks the user to adjust the suggested default tradeoff strategy by improving some attribute to see how much worse the attribute being traded off can be made while still being acceptable, and, finally, it asks the user to adjust the default preference on the tradeoff alternatives. This method is consistent with the principles of standard negotiation theory and to demonstrate its effectiveness we implemented a prototype system and performed an empirical evaluation in an accommodation renting scenario. The result of this evaluation indicates the proposed technique is helpful and efficient in accurately acquiring the users’ tradeoff strategies and preferences
Prioritised fuzzy constraint satisfaction problems: axioms, instantiation and validation
No full textThis paper identifies a generic axiom framework for prioritised fuzzy constraint satisfaction problems (PFCSPs), and proposes methods to instantiate it (i.e., to construct specific schemes which obey the generic axiom framework). In particular, we give five methods to construct the priority operators that are used for calculating the local satisfaction degree of a prioritised fuzzy constraint, and identify priority T-norm operators that can be used for calculating the global satisfaction degree of a prioritised fuzzy constraint problem. Moreover, a number of numerical examples and real examples are used to validate our system, and thus we further obtain some insights into our system. In addition, we explore the relationship between weight schemes and prioritised FCSP schemes, and reveal that the weighted FCSP schemes are the dual of prioritised FCSP schemes, which can, correspondingly, be called posterioritised FCSP schemes
Acquiring domain knowledge for negotiating agents: a case study
No full textIn this paper, we employ the fuzzy repertory table technique to acquire the necessary domain knowledge for software agents to act as sellers and buyers using a bilateral, multi-issue negotiation model that can achieve optimal results in semi-competitive environments. In this context, the seller's domain knowledge that need to be acquired is the rewards associated with the products and restrictions attached to their purchase. The buyer's domain knowledge that is acquired is the requirements and preferences on the desired products. The knowledge acquisition methods we develop involve constructing three fuzzy repertory tables and their associated distinctions matrixes. The first two are employed to acquire the seller agent's domain knowledge; and the third one is used, together with an inductive machine learning algorithm, to acquire the domain knowledge for the buyer agent
A spectrum of compromise aggregation operators for multi-attribute decision making.
No full textIn many decision making problems, a number of independent attributes or criteria are often used to individually rate an alternative from an agent’s local perspective and then these individual ratings are combined to produce an overall assessment. Now, in cases where these individual ratings are not in complete agreement, the overall rating should be somewhere in between the extremes that have been suggested. However, there are many possibilities for the aggregated value. Given this, this paper systematically explores the space of possible compromise operators for such multi-attribute decision making problems. Specifically, we axiomatically identify the complete spectrum of such operators in terms of the properties they should satisfy, and show the main ones that are widely used—namely averaging operators, uninorms and nullnorms—represent only three of the nine types we identify. For each type, we then go onto analyse their properties and discuss how specific instances can actually be developed. Finally, to illustrate the richness of our framework, we show how a wide range of operators are needed to model the various attitudes that a user may have for aggregation in a given scenario (bidding in multi-attribute auctions)
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M-estimator, and D-optimality model construction using orthogonal forward regression
No full textThis correspondence introduces a new orthogonal forward regression (OFR) model identification algorithm using D-optimality for model structure selection and is based on an M-estimators of parameter estimates. M-estimator is a classical robust parameter estimation technique to tackle bad data conditions such as outliers. Computationally, The M-estimator can be derived using an iterative reweighted least squares (IRLS) algorithm. D-optimality is a model structure robustness criterion in experimental design to tackle ill-conditioning in model Structure. The orthogonal forward regression (OFR), often based on the modified Gram-Schmidt procedure, is an efficient method incorporating structure selection and parameter estimation simultaneously. The basic idea of the proposed approach is to incorporate an IRLS inner loop into the modified Gram-Schmidt procedure. In this manner, the OFR algorithm for parsimonious model structure determination is extended to bad data conditions with improved performance via the derivation of parameter M-estimators with inherent robustness to outliers. Numerical examples are included to demonstrate the effectiveness of the proposed algorithm
Volutellonectria asiana J. Luo, X. M. Zhang & W. Y. Zhuang 2012, sp. nov.
No full textVolutellonectria asiana J. Luo, X.M. Zhang & W.Y. Zhuang, sp. nov. FIGS.2A− B, 3A− H MycoBank MB561607 Etymology. The specific epithet refers to the locality of the fungus. Ascomata on old sporodochia or thin basal stromata, perithecial, solitary or 2−5 in a group, superficial, obpyriform, 110−210 µm high, 85−190 µm diam, with a small and red papilla, not collapsing or laterally collapsing when dry, red-orange when fresh and orange to red-orange when dry, turning dark red in 3% KOH and orange-yellow in lactic acid, smooth. Ascomatal wall 7.5−12 µm thick, of two layers; outer layer 6−9.5 µm thick, cells angular, 4−7.5 × 2.5−5 µm, cell wall 0.5−1.5µm thick; inner layer 1.5−3.5 µm thick, cells flattened, 5−11 × 1−2 µm, cell wall 0.5−1 µm thick. Asci subcylindrical to clavate, 8-spored, with an apical ring, 35−47 × 4−6 µm (n = 50). Ascospores subfusoid, uniseptate, not constricted at the septum, hyaline, smooth, irregularly biseriate, 9.5−15 × 2−3 µm (n = 50). Sporodochia solitary or gregarious on substrate, usually stipitate, with a small basal stroma, 75−145 µm diam. Seta arising from sporodochial base and surrounding the conidiophores, 175−325 µm long, 3−5.5 µm wide at base, tapering to a round apex, 1−4-septate, smooth, hyaline, walls 0.5−1.5 µm thick. Conidiophores branched, 2540 µm long, 2−3 µm wide at base, closely aggregated. Conidiogenous cells in whorls of 2−4, adpressed, straight, cylindrical, slightly tapering towards the tip, 6.5−13 µm long, 1.5−2.5 µm wide at base, 0.5−1.5 µm near aperture (n = 50). Conidia rod-shaped, distally rounded, with a median displaced hilum, straight, 1-celled, hyaline, smooth, 4−8.5 × 1.5−2.5 µm (n = 50). Colonies on PDA 3 cm diam after 5 d in the dark at 24 C, pale pinkish cinnamon, surface velvety, aerial mycelium white to yellowish, reverse light pinkish cinnamon. Colonies on (CMD) reaching 2.5 cm diam after 5 d in the dark at 24 C, pale pinkish buff, surface felty, aerial mycelium absent to sparse, reverse light buff. Conidiophores simple, unbranched, erect, septate. Conidiogenous cells cylindrical, slightly tapering towards the tip, 15−52 µm long, 1−1.5 µm wide at base, 0.51 µm near aperture (n = 50). Conidia subellipsoid to subfusoid, distally rounded, with a median displaced hilum, straight, 1-celled, hyaline, smooth, 4−11.5 × 1.5− 2.5 µm (n = 50). Sporodochia not observed. Holotype. CHINA. HAINAN, Bawanling, 1100 m, on leaves of a palm, 6 July 2000, Zhuang W. Y., Wu W. P. and Zhang X. M., H17, HMAS 76861, ex type culture HMAS 188475. Paratype. Thailand. Saraburi, Khao Yai National Park, Phaedeodai, 1100 m, on Pandanus sp., 12 August 1997, Samuels G. J . and Chaverri P., 8410, BPI 745740. Notes. Volutellonectria asiana is most similar to V. consors in having red-orange and obpyriform perithecia with a red papilla, subcylindrical to clavate asci with an apical ring, hyaline ascospores with a smooth surface, smooth-walled sporodochial setae, 1-celled conidia, and light-colored colonies. V. consors, however, differs in having larger perithecia 210−270 µm high and 150−220 µm diam, a hairy perithecial surface, thicker perithecial walls 15−25 µm thick, somewhat longer asci 40−55 µm long, wider ascospores 3− 4 µm wide, ellipsoid conidia, and red sclerotia formed in culture (Samuels 1977). Our molecular data also support the establishment of V. asiana as a new species (FIG. 1). The two isolates are grouped together with high statistical support (1.00 BIPP; 100% BP) and separated from the morphologically similar species, V. consors.Published as part of Luo, Jing & Zhuang, Wen-Ying, 2012, Volutellonectria (Ascomycota, Fungi), a new genus with Volutella anamorphs, pp. 1-10 in Phytotaxa 44 on pages 5-6, DOI: 10.11646/phytotaxa.44.1.1, http://zenodo.org/record/489498
Rosa tomurensis L. Luo, C. Yu & Q. X. Zhang
No full textRosa tomurensis L. Luo, C. Yu & Q. X. Zhang (Figures 3, 4, 5) Type: — CHINA. Xinjiang Uygur autonomous region, Akesu Prefecture, Wensu County, Tuomuerfeng Natural Preservation Areas, in river valleys, ca. 1800m, 10 June 2017, L. Luo, C. Yu, Y. J. Sui, F. Yang & S. Zhao 171022 (holotype BJFC00107674!). Diagnosis: — R. tomurensis is different from R. laxa in the following characteristics: prickles are rare, single prickles are larger, and the tip of prickles is not curved significantly; leaf blade apex serrate only, subbase one-third entire; flowers often solitary, and single flowers are larger than R. laxa; receptacles purplish red, occasionally green; pedicels very long, purplish red or green; sepals are purplish red or green; hips are larger than R. laxa, often pendulous, hip apex without short neck; hip pedicels slightly inflated at base; sepals abaxially, receptacle and pedicel glandular or glandless together, the glands in the pedicel sometimes shed at anaphase. (Table 2). Description: —Shrubs, erect, 2.5–3 m tall, basal branching. Branchlets slender, brownish red; branchial spines are rare, scattered, rarely opposite, pale yellow and white, unequal in length, slender, broad at base, apex slightly downward curved. Leaflets 5–9, usually 7, elliptic, obovoid, ovoid or oblong, 0.6–2 × 0.5–1 cm, abaxially sparsely pilose, adaxially smooth; leaf margin simple serrate, often entire subbase one-third. Stipules usually wider, base mostly adnate to petiole, free portion ovate, triangulate, margin glandular spot. Flowers often solitary, sometimes 2–3 in corymbose cymes, (3) 3.5–6.5 (7) cm in diam; pedicel 1.5–3.5 cm, pedicel and calyx tube glabrous or tomentose and sparsely glandular hairs; bracts ovate, margin glandular teeth, abaxially with distinct midrib and lateral veins; sepals long lanceolate, margin entire, apex elongated widened into appendages, abaxially glandular and densely tomentose, adaxially densely pubescent, margin more densely; petals white, sparse pink,or pale pink, at bud stage, petal tips are often pink or pale pink. Hip subglobose or ovoid, red, shiny, 1–2.1cm in diam, 1.5–2 cm long, sepals persistent and spreading; fruit pedicel straight or bent. Distribution and habitat: —This species is produced in the Tuomuerfeng Natural Preservation Areas of Wensu County in Aksu Perfecture, the Pamir Plateau Mountain Area of Kizilsu Kirgiz Autonomous Prefecture, Tajik Autonomous County of Taxkorgan in Kashgar Prefecture and the south slope of Duku Highway, Xinjiang Uygur Autonomous Region. It borns in arid mountains, river valleys and riparian thickets, at elevations between 1700 m and 3000 m. The associated woody plants in this area are R. laxa, R. albertii, Berberis sp., Caragana sp., etc. Phenology: —Flowering from June to July, fruiting from August to October. Etymology: —The specific epithet refers to the distribution where the new species was first discovered. Paratypes: — CHINA. Xinjiang Uygur autonomous region, Akesu Prefecture, Wensu County, Tuomuerfeng Natural Preservation Areas, in river valleys, ca. 1800m, 24 September 2017, L. Luo, C. Yu, Y. J. Sui, F. Yang & S. Zhao 171023 (BJFC00107688!); the same locality, 8 June 2017, L. Luo, C. Yu, Y. J. Sui, F. Yang & S. Zhao 171024 (BJFC00107671!). Conservation status: —Based on currently available data, the species should be assigned to the ‘Data Deficient’ (DD) category of IUCN (2022). There is little human interference in this species’ distribution areas, so these populations are not easy to be destroyed.Published as part of Deng, Tong, Luo, Le, Yu, Chao, Zhang, Qi-Xiang, Liu, Xue-Sen & Deng, Ze-Yi, 2022, Rosa tomurensis, a new species of Rosa (Rosaceae) from China, pp. 169-177 in Phytotaxa 556 (2) on pages 174-175, DOI: 10.11646/phytotaxa.556.2.6, http://zenodo.org/record/696599
Relations between x-ray timing features and spectral parameters of galactic black hole x-ray binaries
No full textWe present a study of correlations between spectral and timing parameters for a sample of black hole X-ray binary candidates. Data are taken from GX
339-4, H 1743-322, and XTE J1650-500, as the Rossi X-ray Timing Explorer
(RXTE) observed complete outbursts of these sources. In our study we investigate outbursts that happened before the end of 2009 to make use of the high-energy coverage of the HEXTE detector and select observations that
show a certain type of quasi-periodic oscillations (type-C QPOs). The spectral parameters are derived using the empirical convolution model simpl to model the Comptonized component of the emission together with a disc blackbody for the emission of the accretion disc. Additional spectral features, namely a reflection component, a high-energy cut-off, and excess emission at 6.4 keV, are taken into account. Our investigations confirm the known positive
correlation between photon index and centroid frequency of the QPOs and reveal an anti-correlation between the fraction of up-scattered photons and the QPO frequency. We show that both correlations behave as expected in the “sombrero”
geometry. Furthermore, we find that during outburst decay the correlation between photon index and QPO frequency follow a general track, independent of individual outbursts
Land Cover Data Set
No full textThis data set is developed by the Institute of Geographical Sciences and Natural Resources Research (IGSNRR, http://www.igsnrr.ac.cn) of the Chinese Academy of Sciences (CAS). It includes land cover raster maps of China produced based on the digital images of AVHRR and the land use raster map of China with the Landsat TM/ETM digital images as the main data sources (see reference literature below). Access to the released data will be restricted to TAMU employees, as well as official visiting scholars on campus, using a computer with TAMU IP address only. This data can also be purchased directly from IGSNRR; those interested should contact: Professor Jiyuan LIU, Director General, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences Building 917, Datun Road, Anwai, Beijing 100101, P.R.China. Tel:+86 10 6488 9281 Fax:+86 10 6485 1844. Email: [email protected] Land Use and Land Cover Change data is accessible only from the campus network of Texas A&M University.Provider of LUCC dataset: Liu, J., Liu M., Deng X., Zhuang D., Zhang Z., and Luo D. 2002. The Land-use and land-cover change database and its relative studies in China. Journal of Geographical Sciences 12(3): 275-282.Provider of LUCC metadata: Liu, J., Liu M., Zhuang D., Zhang Z., and Deng X. 2003. Study on spatial pattern of land-use change in China during 1995-2000. Science in China (D) 46(4): 373-384.Provider of LUCC dataset: Liu, J., Zhuang D., Luo D., and Xiao, X. 2003. Land-cover Classification of China: Integrated Analysis of AVHRR Imagery and Geo-physical Data. International Journal of Remote Sensing 24(12): 2485-2500
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