The femtosecond optical trapping capability and the effect of femtosecond laser pulses on cell viability were studied. The maximum lateral velocity at which the particles just failed to be trapped, together with the measured average trapping power, were used to calculate the lateral trapping force (Q-value). The viability of the cells after femtosecond laser trapping was ascertained by vital staining. Measurement of the Q-values shows that femtosecond optical tweezers are just as effective as continuous wave optical tweezers. The experiments demonstrate that there is a critical limit for exposure time at each corresponding laser power of femtosecond optical tweezers, and femtosecond laser tweezers are safe for optical trapping at low power with short exposure time.

Acutely isolated mouse hippocampal CA3 pyramidal neurons were exposed to 3 mT static magnetic field, and the characteristics of transient outward K⁺ channel were studied using the whole-cell patch-clamp technique. The experiment revealed that the amplitude of transient outward potassium channel current was reduced. The maximum activated current densities of control group and exposure group were 163.62±20.68 pA/pF and 98.74±16.57 pA/pF(n=12, P<0.01)respectively. The static magnetic field exposure affected the activation and inactivation process of transient outward potassium channel current. Due to the magnetic field exposure, the halfactivation voltage of the activation curves changed from 5.59±1.96 mV to 27.87±7.24 mV(n=12, P<0.05), and the slope factor changed from 19.43±2.11 mV to 25.87±4.22 mV(n=12, P<0.05). The half-inactivation voltage of the inactivation curves also changed from −56.09±0.89 mV to −57.16±1.10 mV(n=12, P>0.05)and the slope factor of the inactivation curves from 8.69±0.80 mV to 10.87±1.02 mV(n=12, P<0.05). The results show that the static magnetic field can change the characteristics of transient outward K⁺ channel, and affect the physiological functions of neurons.

A second-order mixing difference scheme with a limiting factor is deduced with the reconstruction gradient method and applied to discretizing the Navier-Stokes equation in an unstructured grid. The transform of nonorthogonal diffusion items generated by the scheme in discrete equations is provided. The Delaunay triangulation method is improved to generate the unstructured grid. The computing program based on the SIMPLE algorithm in an unstructured grid is compiled and used to solve the discrete equations of two types of incompressible viscous flow. The numerical simulation results of the laminar flow driven by lid in cavity and flow behind a cylinder are compared with the theoretical solution and experimental data respectively. In the former case, a good agreement is achieved in the main velocity and drag coefficient curve. In the latter case, the numerical structure and development of vortex under several Reynolds numbers match well with that of the experiment. It is indicated that the factor difference scheme is of higher accuracy, and feasible to be applied to Navier-Stokes equation.

This paper analyses the changing rule of indoor ozone concentration and its influencing factors. A formula of indoor-outdoor concentration ratio (I/O ratio) was deduced based on the indoor ozone mass-balance equation. The ozone I/O ratio in different kinds of buildings was studied. Results show that I/O ratio is much related to air-exchange rate, which is well compatible with the theoretical calculation results.

In this paper, the hydrodynamically generated noise by the flow over an open cavity is studied. First, aeroacoustic theories and computational aeroacoustic (CAA) methodologies are reviewed in light of hydrodynamic acoustics, based on which, a hybrid method is presented. In the coupling procedure, the unsteady cavity flow field is computed using large-eddy simulation (LES), while the radiated sound is calculated by the Ffowcs Williams-Hawkings (FW-H) acoustic analogy with acoustic source terms extracted from the time-dependent solutions of the unsteady flow. The hybrid LES-FW-H acoustic analogy method is tested with an open cavity flow at Mach number of 0.006 and Reynolds number of 10⁵. Following the reflection theorem of Powell, the contributions from different source terms are quantified, and the terms involving wall-pressure fluctuations are found to account for most of the radiated intensity. The radiation field is investigated in the frequency domain. For the longitudinal direction, the sound propagates with a dominant radiation downstream the cavity in the near-field and a flatter directivity in the far-field, while for the spanwise direction, the acoustic waves have a similar propagation along +z and −z directions, with no visible directivity.

Since most ad hoc mobile devices today operate on batteries, the power consumption becomes an important issue. This paper proposes a cross-layer design of energy-aware ad hoc on-demand distance vector (CEAODV) routing protocol which adopts cross-layer mechanism and energy-aware metric to improve AODV routing protocol to reduce the energy consumption and then prolong the life of the whole network. In CEAODV, the link layer and the routing layer work together to choose the optimized transmission power for nodes and the route for packets. The link layer provides the energy consumption information for the routing layer and the routing layer chooses route accordingly and conversely controls the link layer to adjust the transmission power. The simulation result shows that CEAODV can outperform AODV to save more energy. It can reduce the consumed energy by about 8% over traditional energy-aware algorithm. And the performance is better when the traffic load is higher in the network.

An accurate circuit of PWM/PFM mode converting and a circuit of auto-adaptively adjusting dimension of power transistor are described. The duty cycle of the signal when the control mode converts can be gained accurately by using ratios of currents and capacitances, and an optimal dimension of power transistor is derived with different loads. The converter is designed by 0.35 µm standard CMOS technology. Simulation results indicate that the converter starts work at 0.8 V input voltage. Combined with synchronized rectification, the transfer efficiency is higher than 90% with full load range, and achieves 97.5% at rating output.

Modification of poly(tetrafluoroethylene) (PTFE) films with 2-methacryloyloxyethyl phosphorylcholine (MPC) was performed by low-temperature plasma treatment and grafting polymerization. Surface properties of PTFE were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra, X-ray photoelectron spectroscopy (XPS), and static contact angle. The results show that MPC has been grafted onto PTFE film surface successfully. Contact angle for the modified PTFE films in the water decreased from 108° to 58.25°, while surface energy increased from 17.52 mN/m to 45.47 mN/m. The effects of plasma treatment time, monomer concentration and grafting time on degree of grafting were determined. In the meanwhile, blood compatibility of the PTFE films was studied by checking thrombogenic time of blood plasma.

In this paper, the wind load on an arc-shaped canopy roof was studied with numerical wind tunnel method (NWTM). Three-dimensional models were set up for the canopy roof with opened or closed skylights. The air flow around the roof under wind action from three directions was analysed respectively. Wind pressure coefficients on the canopy roof were determined by NWTM. The results of NWTM agreed well with those of wind tunnel test for the roof with opened skylights, which verified the applicability and rationality of NWTM. The effect of the closure of skylights was then investigated with NWTM. It was concluded that the closure of the skylights may increase the wind suction on the top surface of the roof greatly and should be considered in the structure design of the canopy roof.

The central composite design in the modeling and optimization of catalytic dehydration of ethanol to ethylene was performed to improve the ethylene yield. A total of 20 experiments at random were conducted to investigate the effect of reaction temperature, Si/Al ratios of H-ZSM-5 catalyst and liquid hourly space velocity (LHSV) on the ethylene yield. The results show that the relationship between ethylene yield and the three significant independent variables can be approximated by a nonlinear polynomial model, with R-squared of 99.9% and adjusted R-squared of 99.8%. The maximal response for ethylene yield is 93.4% under the optimal condition of 328 °C, Si/Al ratio 85, and LHSV 3.8 h⁻¹.

This paper focuses on the quantitative expression of bacterial regrowth in water distribution system. Considering public health risks of bacterial regrowth, the experiment was performed on a distribution system of selected area. Physical, chemical, and microbiological parameters such as turbidity, temperature, residual chlorine and pH were measured over a three-month period and correlation analysis was carried out. Combined with principal components analysis (PCA), a logistic regression model is developed to predict and diagnose bacterial regrowth and locate the zones with high risks of microbiology in the distribution system. The model gives the probability of bacterial regrowth with the number of heterotrophic plate counts as the binary response variable and three new principal components variables as the explanatory variables. The veracity of the logistic regression model was 90%, which meets the precision requirement of the model.

Mutual information (MI)-based image registration is effective in registering medical images, but it is computationally expensive. This paper accelerates MI-based image registration by dividing computation of mutual information into spatial transformation and histogram-based calculation, and performing 3D spatial transformation and trilinear interpolation on graphic processing unit (GPU). The 3D floating image is downloaded to GPU as flat 3D texture, and then fetched and interpolated for each new voxel location in fragment shader. The transformed results are rendered to textures by using frame buffer object (FBO) extension, and then read to the main memory used for the remaining computation on CPU. Experimental results show that GPU-accelerated method can achieve speedup about an order of magnitude with better registration result compared with the software implementation on a single-core CPU.

Cameras can reliably detect human motions in a normal environment, but they are usually affected by sudden illumination changes and complex conditions, which are the major obstacles to the reliability and robustness of the system. To solve this problem, a novel integration method was proposed to combine bi-static ultra-wideband radar and cameras. In this recognition system, two cameras are used to localize the object’s region, regions while a radar is used to obtain its 3D motion models on a mobile robot. The recognition results can be matched in the 3D motion library in order to recognize its motions. To confirm the effectiveness of the proposed method, the experimental results of recognition using vision sensors and those of recognition using the integration method were compared in different environments. Higher correct-recognition rate is achieved in the experiment.

In this paper, three different modeling ranges were selected in the structural analysis for a hydropower house. The analysis was carried out using ABAQUS 6.6. The modeling range has a remarkable effect on finite element method (FEM) calculation result at the middle position of typical cross-sections where the concrete is relatively thin, and at the region close to turbine floor. If the ventilation barrel, floor slabs and columns above turbine floor are excluded from FEM model, the maximum rise difference of pedestal structure increases by about 24% compared with that of the whole model. It is indicated that different modeling ranges indeed affect FEM calculation result, and the structure above turbine floor in the FEM model should be included.