Four-dimensional dynamic flow measurement by holographic particle image velocimetry

The ultimate goal of holographic particle image velocimetry (HPIV) is to provide space- and time-resolved measurement of complex flows. Recent new understanding of holographic imaging of small particles, pertaining to intrinsic aberration and noise in particular, has enabled us to elucidate fundamental issues in HPIV and implement a new HPIV system. This system is based on our previously reported off-axis HPIV setup, but the design is optimized by incorporating our new insights of holographic particle imaging characteristics. Furthermore, the new system benefits from advanced data processing algorithms and distributed parallel computing technology. Because of its robustness and efficiency, for the first time to our knowledge, the goal of both temporally and spatially resolved flow measurements becomes tangible. We demonstrate its temporal measurement capability by a series of phase-locked dynamic measurements of instantaneous three-dimensional, three-component velocity fields in a highly three-dimensional vortical flow--the flow past a tab

Diversification in the international construction business

Economic globalization has created an interdependent market that allows companies to transcend traditional national boundaries to conduct business overseas. In the international construction market, companies often adopt diversification as a strategy for growth, for risk management or for both. However, the diversification patterns of international construction companies (ICCs) as a group are barely clear. The primary aim of this research is to cover this knowledge void by mapping ICCs’ diversification patterns in both business sectors and geographical dispersal. It starts from a literature review of diversification theories. Based on the review, a series of hypotheses relating to ICCs’ diversification are proposed. Data are gleaned from Engineering News-Record, i.e. Bloomberg and Capital IQ, ranging from 2001 to 2015. By testing the hypotheses, it is found that larger ICCs prefer to diversify than their smaller counterparts. Most of the ICCs tend to diversify to geographical markets with similar cultural or institutional environment. Market demands drive ICCs to diversify to different geographical markets while they are more prudential in venturing into new business sectors. The research provides not only valuable insights into diversification patterns of ICCs, but also a solid point of departure for future theoretical and empirical studies

Progenitor delay-time distribution of short gamma-ray bursts: Constraints from observations

Context. The progenitors of short gamma-ray bursts (SGRBs) have not yet been well identified. The most popular model is the merger of compact object binaries (NS-NS/NS-BH). However, other progenitor models cannot be ruled out. The delay-time distribution of SGRB progenitors, which is an important property to constrain progenitor models, is still poorly understood. Aims. We aim to better constrain the luminosity function of SGRBs and the delay-time distribution of their progenitors with newly discovered SGRBs. Methods. We present a low-contamination sample of 16 Swift SGRBs that is better defined by a duration shorter than 0.8 s. By using this robust sample and by combining a self-consistent star formation model with various models for the distribution of time delays, the redshift distribution of SGRBs is calculated and then compared to the observational data. Results. We find that the power-law delay distribution model is disfavored and that only the lognormal delay distribution model with the typical delay tau >= 3 Gyr is consistent with the data. Comparing Swift SGRBs with T90 > 0.8 s to our robust sample (T90 < 0.8 s), we find a significant difference in the time delays between these two samples. Conclusions. Our results show that the progenitors of SGRBs are dominated by relatively long-lived systems (tau >= 3 Gyr), which contrasts the results found for Type Ia supernovae. We therefore conclude that primordial NS-NS systems are not favored as the dominant SGRB progenitors. Alternatively, dynamically formed NS-NS/BH and primordial NS-BH systems with average delays longer than 5 Gyr may contribute a significant fraction to the overall SGRB progenitors.Comment: 8 pages, 6 figures, Astron. Astrophys. in pres

Efficiency of Internal Capital Allocation and the Success of Acquisitions

Does efficient internal investment generally translate into successful external investment activities? In this research we use the internal capital allocation efficiency as a proxy for the efficiency of internal investment, and study whether firms that are internally efficient also make efficient external investment decisions. Our sample consists of multi-segment acquirers that announce acquisitions between 1986 and 2003 (only completed deals are included). We estimate short-term and long-term abnormal performance, excess value and operating performance around mergers in order to measure the success of acquisitions (external investment decisions). Our results indicate that internal capital allocation efficiency is indeed a significant factor in the success of acquisition. Firms that are internally efficient also make efficient external investment decisions. Conversely, internally inefficient firms are also externally inefficient. Thus, our results indicate that internal efficiency can be used as a predictor of the success and efficiency of external investment decisions

Analysis of factors influencing China's accession to the GPA

China, with a huge market in government procurement, submitted an application to join the WTO GPA and formally began the negotiating process with the other signatories to the Agreement while the current parties were revising the 1994 GPA. International trade is not simply the outcome of market forces, of relative supply and demand. Rather, it is the result of a complex and interlocking network of bargains that are partly economic and partly political. This article discusses the main factors influencing China’s accession to the GPA from the perspective of trade negotiation, outlines the possible emerging problems and difficulties in the course of the accession and provides a brief recommendation to make the negotiations go on wheels