The Wild, Wild Web

Hitchcock, Jayne 숙명여자대학교 아시아여성연구소 2002 Asian Women Vol.14 No.-

The effects of topography on local wind-induced pressures of a medium-rise building

Hitchcock, P.A.,Kwok, K.C.S.,Wong, K.S.,Shum, K.M. Techno-Press 2010 Wind and Structures, An International Journal (WAS Vol.13 No.5

Wind tunnel model tests were conducted for a residential apartment block located within the complex terrain of The Hong Kong University of Science and Technology (HKUST). The test building is typical of medium-rise residential buildings in Hong Kong. The model study was conducted using modelling techniques and assumptions that are commonly used to predict design wind loads and pressures for buildings sited in regions of significant topography. Results for the building model with and without the surrounding topography were compared to investigate the effects of far-field and near-field topography on wind characteristics at the test building site and wind-induced external pressure coefficients at key locations on the building facade. The study also compared the wind tunnel test results to topographic multipliers and external pressure coefficients determined from nine international design standards. Differences between the external pressure coefficients stipulated in the various standards will be exacerbated when they are combined with the respective topographic multipliers.

ELECTRICAL TRANSPORT PROPERTIES OF SINGLE-WALLED CARBON NANOTUBE BUNDLES TREATED WITH BORIC ACID

DALE HITCHCOCK,KEQIN YANG,JIAN HE,APPARAO M. RAO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.4

Electric-arc-synthesized single-walled carbon nanotube (SWNT) bundles were sonicated in boric acid, dried and sintered under vacuum at 1200°C using a spark plasma sintering process. The nominal boric acid concentrations were 0%, 2.5%, 5%, 7.5%, 12.5% and 15%. This resulted in a nonmonotonic variation of carrier concentration in the resulting samples. The 7.5% boric acid treated sample showed the least magnitude and weakest temperature-dependence for the thermopower with a distinct phonon-drag peak that was absent in the other samples. These results are discussed within the framework of the doping-induced shift of the Fermi level and changes in the electron–phonon coupling.

Needed: A Positive, Better Funded U.S. Foreign Policy

David HITCHCOCK 신아시아연구소(구 신아세아질서연구회) 2001 신아세아 Vol.8 No.1

The effects of topography on local wind-induced pressures of a medium-rise building

P.A. Hitchcock,K.C.S. Kwok,K.S. Wong,K.M. Shum 한국풍공학회 2010 Wind and Structures, An International Journal (WAS Vol.13 No.5

Wind tunnel model tests were conducted for a residential apartment block located within the complex terrain of The Hong Kong University of Science and Technology (HKUST). The test building is typical of medium-rise residential buildings in Hong Kong. The model study was conducted using modelling techniques and assumptions that are commonly used to predict design wind loads and pressures for buildings sited in regions of significant topography. Results for the building model with and without the surrounding topography were compared to investigate the effects of far-field and near-field topography on wind characteristics at the test building site and wind-induced external pressure coefficients at key locations on the building façade. The study also compared the wind tunnel test results to topographic multipliers and external pressure coefficients determined from nine international design standards. Differences between the external pressure coefficients stipulated in the various standards will be exacerbated when they are combined with the respective topographic multipliers.

Provably Secure Tripartite Password Protected Key Exchange Protocol Based on Elliptic Curves

Lee, S.,Hitchcock, Y.,Park, Y.,Moon, S. SPRINGER-VERLAG 2006 Lecture Notes in Computer Science Vol.3897 No.-

Password Authenticated One Round Tripartite Key Exchange Protocol based on Elliptic Curves

SangGon Lee(이상곤),Yvonne Hitchcock,YoungHo Park(박영호),SangJae Moon(문상재) 한국멀티미디어학회 2005 한국멀티미디어학회 학술발표논문집 Vol.2005 No.1

Evaluation of mode-shape linearization for HFBB analysis of real tall buildings

Tse, K.T.,Yu, X.J.,Hitchcock, P.A. Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.18 No.4

The high frequency base balance (HFBB) technique is a convenient and relatively fast wind tunnel testing technique for predicting wind-induced forces for tall building design. While modern tall building design has seen a number architecturally remarkable buildings constructed recently, the characteristics of those buildings are significantly different to those that were common when the HFBB technique was originally developed. In particular, the prediction of generalized forces for buildings with 3-dimensional mode shapes has a number of inherent uncertainties and challenges that need to be overcome to accurately predict building loads and responses. As an alternative to the more conventional application of general mode shape correction factors, an analysis methodology, referred to as the linear-mode-shape (LMS) method, has been recently developed to allow better estimates of the generalized forces by establishing a new set of centers at which the translational mode shapes are linear. The LMS method was initially evaluated and compared with the methods using mode shape correction factors for a rectangular building, which was wind tunnel tested in isolation in an open terrain for five incident wind angles at $22.5^{\circ}$ increments from $0^{\circ}$ to $90^{\circ}$. The results demonstrated that the LMS method provides more accurate predictions of the wind-induced loads and building responses than the application of mode shape correction factors. The LMS method was subsequently applied to a tall building project in Hong Kong. The building considered in the current study is located in a heavily developed business district and surrounded by tall buildings and mixed terrain. The HFBB results validated the versatility of the LMS method for the structural design of an actual tall building subjected to the varied wind characteristics caused by the surroundings. In comparison, the application of mode shape correction factors in the HFBB analysis did not directly take into account the influence of the site specific characteristics on the actual wind loads, hence their estimates of the building responses have a higher variability.

Large-eddy simulation and wind tunnel study of flow over an up-hill slope in a complex terrain

Tsang, C.F.,Kwok, Kenny C.S.,Hitchcock, Peter A.,Hui, Desmond K.K. Techno-Press 2009 Wind and Structures, An International Journal (WAS Vol.12 No.3

This study examines the accuracy of large-eddy simulation (LES) to simulate the flow around a large irregular sloping complex terrain. Typically, real built up environments are surrounded by complex terrain geometries with many features. The complex terrain surrounding The Hong Kong University of Science and Technology campus was modelled and the flow over an uphill slope was simulated. The simulated results, including mean velocity profiles and turbulence intensities, were compared with the flow characteristics measured in a wind tunnel model test. Given the size of the domain and the corresponding constraints on the resolution of the simulation, the mean velocity components within the boundary layer flow, especially in the stream-wise direction were found to be reasonably well replicated by the LES. The turbulence intensity values were found to differ from the wind tunnel results in the building recirculation zones, mostly due to the constraints placed on spatial and temporal resolutions. Based on the validated mean velocity profile results, the flow-structure interactions around these buildings and the surrounding terrain were examined.

Effect of low frequency motion on the performance of a dynamic manual tracking task

Burton, Melissa D.,Kwok, Kenny C.S.,Hitchcock, Peter A. Techno-Press 2011 Wind and Structures, An International Journal (WAS Vol.14 No.6

The assessment of wind-induced motion plays an important role in the development and design of the majority of today's structures that push the limits of engineering knowledge. A vital part of the design is the prediction of wind-induced tall building motion and the assessment of its effects on occupant comfort. Little of the research that has led to the development of the various international standards for occupant comfort criteria have considered the effects of the low-frequency motion on task performance and interference with building occupants' daily activities. It has only recently become more widely recognized that it is no longer reasonable to assume that the level of motion that a tall building undergoes in a windstorm will fall below an occupants' level of perception and little is known about how this motion perception could also impact on task performance. Experimental research was conducted to evaluate the performance of individuals engaged in a manual tracking task while subjected to low level vibration in the frequency range of 0.125 Hz-0.50 Hz. The investigations were carried out under narrow-band random vibration with accelerations ranging from 2 milli-g to 30 milli-g (where 1 milli-g = 0.0098 $m/s^2$) and included a control condition. The frequencies and accelerations simulated are representative of the level of motion expected to occur in a tall building (heights in the range of 100 m -350 m) once every few months to once every few years. Performance of the test subjects with and without vibration was determined for 15 separate test conditions and evaluated in terms of time taken to complete a task and accuracy per trial. Overall, the performance under the vibration conditions did not vary significantly from that of the control condition, nor was there a statistically significant degradation or improvement trend in performance ability as a function of increasing frequency or acceleration.