Photometric behaviour of the Be star EW Lacertae

The night-to-night and short-term variations inUBV light curves of EW Lac which were made during 1982–1984 at Yonsei University Observatory are discussed. The long-term variability in the photometric behaviour of the star is examined with our own data as well as those of Harmanecet al. (1980).Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.Yonsei University Observatory Contribution No. 23.     

The structure and evolution of trade relations between countries along the Belt and Road

Trade facilitation is one of the five main agendas of the Belt and Road Initiative (BRI). Social network analysis has helped understand the complexity of trade networks, but existing studies tend to overlook the fact that not all bilateral trade relations are equally important to a country. To fill this gap in the literature, this paper focuses on the top 2 trade relations networks to illuminate the structure and evolution of B&R trade relations, the relative positions of different countries, and changes in the composition of trade communities (e.g., the community leaders) and the changing patterns of trade between them. We find rich dynamics over time both inter- and intra-communities. The overall international trade networks of B&R countries experienced a leadership change from Russia to China on one hand, some temporary communities experienced emergence, disappearance (e.g. the Kuwait- and Thailand-led communities) or reemergence (e.g. Poland-led community), and a community membership was generally consistent on the other hand. Since the future impacts of China’s BRI will depend on the degree of integration of the connected regions, some countries with stable and high centrality indices (e.g. Russia, Singapore, Serbia, Greece, Turkey, Iran, Poland, Hungary and Romania) could be selected by China as strategic regional partners, and countries with a strategically important geographical position but weak trade links (e.g. Myanmar, Pakistan, and Belarus) should be prioritized.     

Uncoupled analysis of stabilizing piles in weathered slopes

This paper describes a simplified numerical approach for analyzing the slope/pile system subjected to lateral soil movements. The lateral one-row pile response above and below the critical surface is computed by using load transfer approach. The response of groups was analyzed by developing interaction factors obtained from a three-dimensional nonlinear finite element study. An uncoupled analysis was performed for stabilizing piles in slope in which the pile response and slope stability are considered separately. The non-linear characteristics of the soil–pile interaction in the stabilizing piles are modeled by hyperbolic load transfer curves. The Bishop's simplified method of slope stability analysis is extended to incorporate the soil-pile interaction and evaluate the safety factor of the reinforced slope. Numerical study is performed to illustrate the major influencing parameters on the pile-slope stability problem. Through comparative studies, it has been found that the factor of safety in slope is much more conservative for an uncoupled analysis than for a coupled analysis based on three-dimensional finite element analysis.     

Optimal design of added viscoelastic dampers and supporting braces

This paper presents a simultaneous optimization procedure for both viscoelastic dampers (VEDs) and supporting braces installed in a structure. The effect of supporting braces on the control efficiency of VEDs is also investigated. To apply a general gradient‐based optimization algorithm, closed‐form expressions for the gradients of objective function and constraints are derived. Also, the constraint on the dynamic behavior of a structure is embedded in the gradient computation procedure to reduce the number of variables in the optimization. From numerical analysis of an example structure, it was found that when sufficient stiffness cannot be provided for the supporting braces, the flexibility of the brace should be taken into account in the design of the VED to achieve the desired performance of the structure. It was also observed that, as a result of the proposed optimization process, the size of the supporting brace could be reduced while the additional VED size (to compensate for the loss of the control effect) was insignificant. Copyright © 2003 John Wiley & Sons, Ltd.     

Semi‐active fuzzy control for seismic response reduction using magnetorheological dampers

A semi‐active fuzzy control strategy for seismic response reduction using a magnetorheological (MR) damper is presented. When a control method based on fuzzy set theory for a structure with a MR damper is used for vibration reduction of a structure, it has an inherent robustness, and easiness to treat the uncertainties of input data from the ground motion and structural vibration sensors, and the ability to handle the non‐linear behavior of the structure because there is no longer the need for an exact mathematical model of the structure. For a clipped‐optimal control algorithm, the command voltage of a MR damper is set at either zero or the maximum level. However, a semi‐active fuzzy control system has benefit to produce the required voltage to be input to the damper so that a desirable damper force can be produced and thus decrease the control force to reduce the structural response. Moreover, the proposed control strategy is fail‐safe in that the bounded‐input, bounded‐output stability of the controlled structure is guaranteed. The results of the numerical simulations show that the proposed semi‐active control system consisting of a fuzzy controller and a MR damper can be beneficial in reducing seismic responses of structures. Copyright © 2004 John Wiley & Sons, Ltd.     

The geometrical factor of a marine resistivity probe with four ring electrodes

Electrical resistivity (or conductivity) is often a useful parameter for investigating the marine sedimentary environment. The resistivity of unconsolidated sediment is usually measured in the laboratory from sample cores. Since the resistivity of sediment is highly dependent upon the pore arrangement and water contents, the laboratory values may not represent those under undisturbed conditions. Because of many practical difficulties and the costs involved, however, in situ resistivity determination for marine sediments is still rare.     

Heterotrophic euglenids from marine sediments of cape tribulation, tropical australia

This paper presents new data on free-living heterotrophic euglenids (Euglenozoa, Protista) that occurred in the marine sediments at Cape Tribulation, Queensland, Australia. Twenty-nine species from 9 genera are described with uninterpreted records based on light microscopy, including one new taxon:Notosolenus capetribulationi n. sp. There was little evidence for endemism because the majority of heterotrophic euglenid species encountered here have been reported or were found from other habitats.     

Redescription of free-living marine nematode, dracograllus filipjevi allen and noffsinger, 1978 (nematoda: draconematidae) from korea

A draconematid nematode species,Dracograllus filipjevi Allen and Noffsinger, 1978, is described from the washings of shallow littoral coralline algae at Guryongpo in the eastern coast of Korea. This species is recognized by the following characteristics: larger body size, number of posterior sublateral adhesion tubes (9 in male and 12-13 in female) and subventral adhesion tubes (8-9 in male and 9-10 in female), the absence of cephalic acanthiform setae on rostrum, the presence of longitudinally areolated body cuticle with dot-like punctations, the presence of some cuticular collar in swollen pharyngeal region, the shape of amphidial fovea (large, elongate, and loop-shaped in both sexes), the absence of preanal corniform setae, and the absence of lateral differentiation on narrow body region. Morphological features of the species using differential interference contrast photomicrographs are described in detail in the present work. This is the first report ofD. filipjevi in Korea.