Competition,cooperation, and performance: an empirical investigation of Chinese online sellers

This study examines the relationship between competition intensity, cooperation network, and performance in the context of electronic commerce. In particular, based on the framework of value net, we study both horizontal and vertical cooperation networks, and test the proposed model empirically. The empirical findings suggest that the more intense the competition, the more willing the sellers are to adopt the strategy of networking. Moreover, both the horizontal and vertical cooperation help to improve performance. The study has interesting theoretical and practical implications.     

An efficient quantum blind digital signature scheme

Recently, many quantum digital signature (QDS) schemes have been proposed to authenticate the integration of a message. However, these quantum signature schemes just consider the situation for bit messages, and the signing-verifying of one-bit modality. So, their signature efficiency is very low. In this paper, we propose a scheme based on an application of Fibonacci-, Lucas- and Fibonacci-Lucas matrix coding to quantum digital signatures based on a recently proposed quantum key distribution (QKD) system. Our scheme can sign a large number of digital messages every time. Moreover, these special matrices provide a method to verify the integration of information received by the participants, to authenticate the identity of the participants, and to improve the efficiency for signing-verifying. Therefore, our signature scheme is more practical than the existing schemes.     

Characterization of chicken antisera raised against Aspergillus spp. by enzyme linked immunosorbent assay

Enzyme linked immunosorbent assays of three Aspergillus species have been developed. Laying hens were immunized with the exoantigens from Asp. flavus, Asp. ochreaus and Asp. versicolor. All test chickens except for one produced antisera raised against the exoantigens. The antisera production process and ELISA titer were analysed. Fourteen days after the first injection, the antisera began to produce largely, on the 35th day reached to the peak, and maintained a stable level until the 42nd day. The maximum ELISA titer of the antisera to the exoantigens from Asp. flavus, Asp. ochreaus and Asp. versicolor was 1:8,000, 1:10,000 and 1:10,000, respectively. The cross-reactivities of antisera were determined with seventeen species of Aspergillus, ten species of fungi from other genera and the buffer-extracts of grain. The antisera did not cross-react with the exoantigens from other genera and the buffer-extracts of grain. The antiserum to exoantigen from Asp. ochreaus was species-specific, whereas the antisera against Asp. flavus and Asp. versicolor tended to cross-react with other Aspergillus species to varying degrees. The results suggest that exoantigens immunoassays can be developed to indentify and detect Aspergillus genus in grains.     

Preparation of vanadium dioxide powders by thermolysis of a precursor at low temperature

A kind of crystal precursor, (NH₄)₅[(VO)₆(CO₃)₄(OH)₉]·10H₂O, less than 12 × 40 m in dimensions was synthesized by reaction of vanadyl dichloride and ammonium hydrocarbonate in solution. The precursor microcrystals were fined to less than 10 m with mean size of about 4 m, by using organic solvents and surfactant in the process of the synthetical technique. Thermolysis of the precursor in a flow of nitrogen gas was investigated by TGA and DTA. The XRD powders patterns for the products from the thermolysis of the precursor show that the VO₂ powder obtained at 350, 365, 380 and 410°C for 30 min were a noncrystalline phase, a monoclinic one named as B phase, a mixed phase of the B and the usual monoclinic A phase, and the pure A phase, respectively. SEM micrographs of VO₂ powders from the fined precursor demonstrated that the particle sizes of these fine powders were less than 2 m. DSC curve of the VO₂ obtained at 450 °C for 30 min from the fined precursor showed that there was an endothermic phase transition at 71 °C.     

Effects of Precursors with Fine BaZrO3 Inclusions on the Growth and Microstructure of Textured YBCO

We prepared precursors with fine BaZrO₃ inclusions for melt-texture growth of high-temperature superconductors with nominal composition of Y_1.5Ba₂Cu₃O _y + x BaZrO₃ (x = 0, 0.04, 0.08, and 0.1), by the process of liquid-phase powder melt-texture growth (LPMG). We then investigated the effects of the precursors on the texture growth and the microstructure of composite YBa₂Cu₃O_7-/Y₂BaCuO₅ (YBCO). The BaZrO₃ particles were about 100 nm in size in the textured YBa₂Cu₃O_7- (Y123), observed by the scanning electron microscopy (SEM). Owing to the pushing effects of growing fronts, fine particles were pushed out of and thus gathered in front of the growing fronts or between Y123 grains. The gathered particles in turn blocked the further growth of the Y123 grains. However, BaZrO₃ particles seeded Y123 grains, giving rise to multigrain growths. These negative effects of BaZrO₃ fine particles exclude themselves as effective flux pinning centers in the textured YBCO.     

1-GHz optical communication system using chaos in erbium-dopedfiber lasers

We experimentally demonstrated an optical communication system based on synchronized chaos between the transmitter and receiver with a sinusoidal signal of 1 GHz. In addition, we also experimented with the modulation of the system by a random bit stream at 140 Mb/s. Both experiments showed that the messages could be recovered at the receiver with a reasonable signal-to-noise ratio. These messages are directly embedded into the chaos through an electrooptic modulator in the transmitter. At the receiver the message is successfully recovered by both the subtracting method and the dividing method     

尼龙片基型传动带接头用胶粘剂及粘接方法的研究

对尼龙片基型传动带接头龟裂的原因、胶粘剂的配制以及粘接方法的选择进行了分析     

Decentralized active control of a class of uncertain cable-stayed flexible structures

This paper addresses the problem of designing robust stabilizing controllers for a class of cable-stayed flexible structures. The dynamic behaviour of the structure is characterized by a beam decomposed into a finite number of concentrated masses. The mathematical model exhibits uncertainties in parameters, stay cable geometry and couplings, as well as in the unknown environmental excitation. The controller design is made based on the principle of sliding mode to reduce the magnitude of the transverse vibrations of the structure induced by the environmental excitation. A numerical simulation example is presented to illustrate the effectiveness of the proposed control scheme.     

Wireless sensor network minimum beacon set selection algorithm based on tree model

Wireless sensor networks (WSNs) are highly attractive both in academia and in practice as a wholly new platform for information transmission. Localization technology is a key technology of WSNs. The structure of the beacon node set is very important to the positioning of the nodes. A method for constructing a minimum beacon set is proposed in this thesis based on the tree model, in which unimportant nodes are identified as early as possible and then pruned. Thus, we avoid unnecessary calculations when establishing the minimum beacon set. This method can provide a reliable guarantee for the unknown node localization. According to our experiment, this algorithm is rapid and stable.