Hong Kong Baptist University

About: Hong Kong Baptist University is a education organization based out in Hong Kong, China. It is known for research contribution in the topics: China & Population. The organization has 7811 authors who have published 18919 publications receiving 555274 citations. The organization is also known as: Hong Kong Baptist College & HKBU.

Efficient Organic Light‐Emitting Diodes based on Sublimable Charged Iridium Phosphorescent Emitters

Abstract: The synthesis and characterization of two new phosphorescent cationic iridium(III) cyclometalated diimine complexes with formula [Ir(L) 2 (N-N)] + (PF 6 - ) (HL=(9,9-diethyl-7-pyridinylfluoren-2-yl)diphenylamine); N-N = 4,4'-dimethyl-2,2'-bipyridine (1), 4,7-dimethyl-1,10-phenanthroline (2)) are reported. Both complexes are coordinated by cyclometalated ligands consisting of hole-transporting diphenylamino (DPA)- and fluorene-based 2-phenylpyridine moieties. Structural information on these heteroleptic complexes has been obtained by using an X-ray diffraction study of complex 2. Complexes 1 and 2 are morphologically and thermally stable ionic solids and are good yellow phosphors at room temperature with relatively short lifetimes in both solution and solid phases. These robust iridium complexes can be thermally vacuum-sublimed and used as phosphorescent dyes for the fabrication of high-efficiency organic light-emitting diodes (OLEDs). These devices doped with 5 wt % 1 can produce efficient electrophosphorescence with a maximum brightness of up to 15 610 cd m -2 and a peak external quantum efficiency of ca. 7 % photons per electron that corresponds to a luminance efficiency of ca. 20 cd A -1 and a power efficiency of ca. 19 lm W -1 . These results show that charged iridium(III) materials are useful alternative electrophosphors for use in evaporated devices in order to realize highly efficient doped OLEDs.

Mapping the criterion space for expatriate success: task- and relationship-based performance, effort and adaptation

Abstract: The paper presents an explicit consideration of the criterion space for expatriate success. Expatriate performance is conceptualized in terms of task completion, relationship building and overall performance. These three dimensions are determined by various features of effort regulation: the amount and pattern of personal resources the expatriate spends on behaviours that constitute his or her position. Drawing upon work motivation and withdrawal literatures, we assess effort in terms of withdrawal cognitions, passive task neglect, active task avoidance, time to proficiency and leader-team exchanges. Effort regulation, in turn, is proposed to be a function of three forms of adjustment (cultural, interaction and work) – which have been the default criterion in past expatriate research. Our model is tested using multi-source data from expatriates, their spouses and their work colleagues. Support for the proposed mapping of successive linkages between adjustment, effort (including the often-studied assignmen...

Differentially private network data release via structural inference

Abstract: Information networks, such as social media and email networks, often contain sensitive information. Releasing such network data could seriously jeopardize individual privacy. Therefore, we need to sanitize network data before the release. In this paper, we present a novel data sanitization solution that infers a network's structure in a differentially private manner. We observe that, by estimating the connection probabilities between vertices instead of considering the observed edges directly, the noise scale enforced by differential privacy can be greatly reduced. Our proposed method infers the network structure by using a statistical hierarchical random graph (HRG) model. The guarantee of differential privacy is achieved by sampling possible HRG structures in the model space via Markov chain Monte Carlo (MCMC). We theoretically prove that the sensitivity of such inference is only O(log n), where n is the number of vertices in a network. This bound implies less noise to be injected than those of existing works. We experimentally evaluate our approach on four real-life network datasets and show that our solution effectively preserves essential network structural properties like degree distribution, shortest path length distribution and influential nodes.

Top-k Monitoring in Wireless Sensor Networks

Abstract: Top-k monitoring is important to many wireless sensor applications. This paper exploits the semantics of top-k query and proposes an energy-efficient monitoring approach called FILA. The basic idea is to install a filter at each sensor node to suppress unnecessary sensor updates. Filter setting and query reevaluation upon updates are two fundamental issues to the correctness and efficiency of the FILA approach. We develop a query reevaluation algorithm that is capable of handling concurrent sensor updates. In particular, we present optimization techniques to reduce the probing cost. We design a skewed filter setting scheme, which aims to balance energy consumption and prolong network lifetime. Moreover, two filter update strategies, namely, eager and lazy, are proposed to favor different application scenarios. We also extend the algorithms to several variants of top-k query, that is, order-insensitive, approximate, and value monitoring. The performance of the proposed FILA approach is extensively evaluated using real data traces. The results show that FILA substantially outperforms the existing TAG-based approach and range caching approach in terms of both network lifetime and energy consumption under various network configurations.