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Rowing Equipment Technology
Published in Franz Konstantin Fuss, Aleksandar Subic, Martin Strangwood, Rabindra Mehta, Routledge Handbook of Sports Technology and Engineering, 2013
Alastair Campbell Ritchie, John Dominy
The rowing oar remained basically unchanged in form from the seventeenth century to the mid-twentieth century, with a long, flat blade at the end of a narrow, wooden shaft, known today as a ‘pencil’ blade. The success of a new, shorter and broader blade design used by the West German team at the European rowing championships in 1959 led to its universal adoption, as the ‘macon’, or ‘spoon’ blade, after the venue for the championships. The next major advance in blade shape was the introduction of the ‘big blade’, also known as the cleaver or hatchet, invented by the Dreissigacker brothers (Concept2 2012) in late 1991 (Miller 2000). The cleaver blade offers a larger surface area, with a shorter blade length. This change in shape translates into a lower bending moment for a given propulsive force at the junction of shaft and blade. As the big-blade oar is normally used with a shorter shaft, the blade is both easier to handle and subject to a reduced bending moment, making the oar more efficient. The asymmetric big blade has a further advantage over the symmetrical macon blade, as the pressure of the water on the blade will exert a moment on the base of the blade face, making it less likely for the rower to ‘catch a crab’ if the blade is not perpendicular to the water as it enters. The macon and cleaver blades are shown in Figure 9.6, with typical dimensions for the blades of sweep oars.
Topoisomerase I inhibitory and photocleavage activity by ruthenium complexes containing a new polyaza ligand
Published in Inorganic and Nano-Metal Chemistry, 2019
Xue-Wen Liu, Jie Huang, Yu-Xuan Tang, Song-Bai Zhang, Ji-Lin Lu
In summary, two new ruthenium (II) complexes have been synthesized and characterized. The DNA-binding, photocleavage properties and Topoisomerase I inhibitory of the complexes have been investigated. The DNA-binding experimental results show that two complexes can act as DNA binder through intercalative mode. Photocleavage studies showed that ruthenium complexes are good photo-reduced DNA cleaver upon irradiation. Furthermore, mechanism studies revealed that singlet oxygen (1O2) is likely to be the reactive species responsible for the DNA photocleavage. And both complexes exhibited a fast singlet oxygen generation rate. This may be the cause of their high DNA photocleavage aibilites. Topo I inhibition studies indicated that complex 2 showed better topo I inhibitory activity than complex 1, and it is an efficient topo I catalytic inhibitor.
Optical fiber refractive index sensor based on the double cladding fiber
Published in Instrumentation Science & Technology, 2022
The optical fiber structure in Figure 2 was fabricated by a fiber cleaver and a fiber fusion splicer. To investigate the RI characteristics, the external RI was changed using glycerol solutions of various concentrations. When the external RI is approximately 1, which is close to the value of air, the transmission spectrum is obtained as shown in the inset in Figure 4. There are three dips in the spectrum from 1200 to 1700 nm named dip1, dip2, and dip3. The first corresponds to the coupling region of the outer cladding mode LP03 and LP05; the second to the resonance region of the core mode LP02 and the outer cladding mode LP05; and the third is likely formed by modal interference.
Predicting indoor deposited particle resuspension with a new probabilistic model based on Markov chain and turbulent burst
Published in Aerosol Science and Technology, 2022
Xiong Mei, Guangcai Gong, Chunwen Xu, Chenni Zeng
In Figure 2, most of the deposited particles in the green area marked as cleaned burst aera are assumed to be removed by turbulent burst. During particle phase simulation, however, deposited particles are initially stored in those additionally added subspaces (blue blocks at the bottom) depicted in Figure 1 instead of laying on the floor surface in the right part of Figure 2. The turbulent bursts occur with a random frequency and the mean time between two bursts Tburst (Cleaver and Yates 1973), which is crucial to the determination of the time step Δt between two consecutive state vectors (usually, Δt should be larger than Tburst in order to observe at least one burst physically), is defined as follows: where νf is the dynamic viscosity of air defined as 1.55 × 10−5 m2/s, and u* is the flow friction velocity. As depicted in Figure 2, the mean diameter D of the turbulent burst impingement area is defined as Equation (13) by Cleaver and Yates(Cleaver and Yates 1973). The axial and the lateral spacing of a single turbulent burst controlled area, which is the rectangle part marked as red shown in Figure 2, can be calculated by Equation (14) and Equation (15), respectively (Cleaver and Yates 1973): where u* is also the friction velocity of the flow previously depicted in Equation (12), and it is formally defined by the following equation: where u∞ is the average air speed in the axial direction (or the so-called mainstream velocity in the present study, which can be obtained from flow field data pre-solved by CFD methods) and f is the Fanning friction factor. ρf is the fluid density with the value of 1.18 kg/m3. In a fully developed turbulent duct flow, Fanning friction factor f can be calculated as (White 1986): where z0 is the mean microscale roughness height of the rough wall with the value of 5 × 10−3 m in the present study for grass material. Re is Reynolds number and Dh is hydraulic diameter, which is defined as the quotient of 4 times the cross-sectional area and the perimeter of the flow duct. Considering the fraction of a single turbulent burst in a single controlled area as constant, the total fraction of the burst areas on the particle laden surface is: