Showing papers by "Qiusheng Li published in 2014"

Electrowetting on liquid-infused film (EWOLF): Complete reversibility and controlled droplet oscillation suppression for fast optical imaging

Abstract: Electrowetting on dielectric (EWOD) has emerged as a powerful tool to electrically manipulate tiny individual droplets in a controlled manner. Despite tremendous progress over the past two decades, current EWOD operating in ambient conditions has limited functionalities posing challenges for its applications, including electronic display, energy generation, and microfluidic systems. Here, we demonstrate a new paradigm of electrowetting on liquid-infused film (EWOLF) that allows for complete reversibility and tunable transient response simultaneously. We determine that these functionalities in EWOLF are attributed to its novel configuration, which allows for the formation of viscous liquid-liquid interfaces as well as additional wetting ridges, thereby suppressing the contact line pinning and severe droplet oscillation encountered in the conventional EWOD. Finally, by harnessing these functionalities demonstrated in EWOLF, we also explore its application as liquid lens for fast optical focusing.

Monitoring of typhoon effects on a super-tall building in Hong Kong

Abstract: SUMMARY A super-tall building with height of 420 m and 88 floors is located in central Hong Kong. Field monitoring of wind effects on the high-rise structure was conducted during the passage of several typhoons on the basis of a wind and movement monitoring system installed in the building. Field data such as wind speed, wind direction, pressures on cladding, acceleration and displacement responses were simultaneously recorded during the typhoons and then analyzed. Typhoon wind parameters including turbulence intensity, gust factor, peak factor, turbulence integral length scale and power spectral density were presented and discussed. The dynamic properties of the high-rise structure were determined from the field measurements and compared with those calculated at the design stage. The damping ratios of the super-tall building were evaluated by a random decrement technique, which demonstrates amplitude-dependent characteristics. The relationships between the structural dynamic responses and the approaching wind speed were analyzed. Wind tunnel tests were conducted to investigate the wind effects on the super-tall building. The field-measured acceleration responses were found to be consistent with the model test results. Finally, the serviceability performance of the super-tall building during the typhoons was assessed on the basis of the field measurement results. The findings of the paper are expected to be of considerable interest and practical use to professionals and researchers involved in wind-resistant designs of super-tall buildings. Copyright © 2013 John Wiley & Sons, Ltd.

Experimental investigation of characteristics of torsional wind loads on rectangular tall buildings

Abstract: In order to investigate the characteristics of torsional wind loads on rectangular tall buildings, five models with different rectangular cross-sections were tested in a boundary wind tunnel. Based on the test results, the RMS force coefficients, power spectrum densities as well as vertical correlation functions of torsional wind loads were analyzed. Formulas that took the side ratio as parameters were proposed to fit the test results above. Comparisons between the results calculated by the formulas and the wind tunnel measurements were made to verify the reliability of the proposed formulas. An simplified expression to evaluate the dynamic torsional wind loads on rectangular tall buildings in urban terrain is presented on basis of the above formulas and has been proved by a practical project. The simplified expressions as well as the proposed formulas can be applied to estimate wind-induce torsional response on rectangular tall buildings in the frequency domain.

Static corrections methods in the processing of deep reflection seismic data

Abstract: Statics are big challenges for the processing of deep reflection seismic data. In this paper several different statics solutions have been implemented in the processing of deep reflection seismic data in South China and their corresponding results have been compared in order to find proper statics solutions. Either statics solutions based on tomographic principle or combining the low-frequency components of field statics with the high-frequency ones of refraction statics can provide reasonable statics solutions for deep reflection seismic data in South China with very rugged surface topography, and the two statics solutions can correct the statics anomalies of both long spatial wavelengths and short ones. The surface-consistent residual static corrections can serve as the good compensations to the several kinds of the first statics solutions. Proper statics solutions can improve both qualities and resolutions of seismic sections, especially for the reflections of Moho in the upmost mantle.

Monitoring of wind effects on a low-rise building during typhoon landfalls and comparison to wind tunnel test results

Abstract: SUMMARY A full-scale instrumented experimental low-rise building was built and implemented to monitor wind effects on the building during typhoons. Field measurements of the near-surface wind velocity field and wind-induced pressures on the low-rise building were carried out during the passages of 10 typhoons in 2008–2011. This paper presents a combined study of field measurements and wind tunnel testing. Detailed analysis of the measured data has been conducted to investigate the typhoon-generated wind characteristics and wind-induced pressures on the roof of the experimental building under extreme wind conditions during typhoon landfalls. On the other hand, wind tunnel experiments have been performed to study the wind loads on the low-rise building. The model test results were compared with the full-scale measurements to evaluate the accuracy of the model test results and the adequacy of the techniques used in the wind tunnel tests. It was found that the wind tunnel tests underestimated the real fluctuating and negative peak pressure coefficients on a roof corner zone for quartering winds. Copyright © 2014 John Wiley & Sons, Ltd.

Hermite Extreme Value Estimation of Non-Gaussian Wind Load Process on a Long-Span Roof Structure

Abstract: This paper presents a combined study of wind tunnel experiment and numerical simulation of the wind-induced pressures on the long-span roof of the Hangzhou East Railway Station Building. Wind tunnel tests were performed on a 1∶250-scale rigid model of the station building. Based on the measured pressure data, the third and fourth statistical moments of the pressure processes were evaluated to quantify the non-Gaussian nature of the wind-induced pressures on the station roof. Using the recently reported Hermite moment model, an analytical form of the non-Gaussian peak factor was proposed for a given hardening load process and was verified using numerical integration. The currently available simulation algorithm was revised to generate sample functions of skewed hardening load processes. The simulated pressure data samples provide a basis for the direct statistical analysis of extreme peaks. The peak factors for non-Gaussian wind load effects were estimated by employing various state-of-the-art meth...

Field measurements of wind characteristics over hilly terrain within surface layer

Abstract: This paper investigates the topographic effects on wind characteristics over hilly terrain, based on wind data recorded at a number of meteorological stations in or near complex terrain. The multiply data sources allow a more detailed investigation of the flow field than is normally possible. Vertical profiles of mean and turbulent wind components from a Sodar profiler were presented and then modeled as functions of height and wind speed. The correlations between longitudinal and vertical wind components were discussed. The phenomena of flow separation and generation of vortices were observed. The distance-dependence of the topographic effects on gust factors was revealed subsequently. Furthermore, the canyon effect was identified and discussed based on the observations of wind at a saddle point between two mountain peaks. This study aims to further understanding of the characteristics of surface wind over rugged terrain. The presented results are expected to be useful for structural design, prevention of pollutant dispersion, and validation of CFD (computational fluid dynamics) models or techniques over complex terrains.