Abstract:In steel frame-reinforced concrete corewall structures, concrete shrinkage and creep directly affect the shortening of corewalls and then influence the shortening of columns through beams, and have a significant impact on the vertical differential shortening. Controlled by time parameter, the displacement method recurrence equation, which takes into account the construction procedure and the concrete shrinkage and creep effect, was used to provide numerical computation for the above problem. The studies show that the long-term concrete shrinkage and creep have great effect on the vertical differential shortening, and that the decreased environment humidity enhances these effects. When considering the concrete shrinkage and creep up to 3 years after the completion of the main structure, the cumulative shortening of concrete corewalls exceeds that of steel columns in top storeys. The axial compressive forces of columns usually increase by more than 10%, and the axial compressive forces of corewalls in top storeys become tensional. The bending directions of some beams reverse to affect beam design.

Abstract:Numerical simulation was used to analyze the mechanical property of steel beam based on membrane effect. The stress distribution of the beam was given and compared with those of steel box-beam and steel H-beam. The results show that, with the same span and mass, the new beam has higher bearing capacity, and with the increase of the span, under rational design, the superiority of the bearing capacity is more evident.

Abstract:To accurately simulate the characteristics of continuously reinforced concrete approach pavement (CRCAP), a simplified concentrated spring model was proposed according to the force-deformation curve and the damage level of the CRCAP. Based on this, a dynamic finite element model of a semi-integral fully jointless bridge (SFJB) was established with SAP2000. The Modal analysis and Time History analysis were carried out on both the SFJB and the continuous girder bridge (CGB) for comparison. The sensitivity analysis of seismic performance was also investigated. The results indicate that the seismic response of the SFJB is only 24%~35% of the CGB in the low seismic fortification intensity zone, which can greatly enhance the seismic resistance of small and medium bridges.

Abstract:In order to solve the multi-objective optimization of structures with constrains, the immune clonal selection algorithm was applied. Based on the immunology theory, the non-dominated neighbor-based selection, proportional cloning and elitism strategy were introduced in the multi-objective immune clonal selection algorithm (MOICSA) to enhance the diversity, the uniformity and the convergence of the solution obtained. Penalty function method was used to deal with violated constraints. Several classical problems were solved to demonstrate the feasibility and effectiveness of the MOICSA algorithm, and the results were compared with other optimization methods. The simulation results show that the algorithm has advantages in convergence speed, time consuming and solution quality.

Abstract:A simplified life cycle cost (LCC) calculation model, which can be applied in project evaluation of open-loop surface water source heat pump system, was set up. Dest-c was used to do the annual energy consumption simulation for an engineering example, and the load demand was analyzed according to the model simulation results and combined with the performance curve of water source heat pump unit and variable frequency pump to calculate the LCC. The results show that water intake temperature, water drainage temperature and height difference between water intake and water drainage are the main factors which influence the LCC of open-loop surface water source heat pump system. By analyzing the above problems and through a further discussion on the measures of system optimization, a conclusion is drawn that, when the water intake temperature is 24 ℃，the best temperature difference between water intake and drainage is 7.7 ℃ under the operation condition of the constant temperature difference, while the minimum LCC is 441.80. In addition, taking into account the unit variant operation to improve the comprehensive energy efficiency of the system, a smaller LCC of 433.50 is obtained, demonstrating that the unit variant operation can further promote energy saving benefit.

Abstract:To deal with the problem of the serious fretting wear of a powertrain gear shaft shoulder in working process, the finite element model of the gear shaft was built with the finite element software ABAQUS. The required minimum interference was calculated through the calculation of interference fit between the gear shaft and the bearing. Simulation results were analyzed to study the effects of the interference fit on the fretting wear of the gear shaft shoulder. By analyzing the effects of the different interferences on the force and deformation of the gear shoulder, the conclusions are as follows: the force between the bearing inner ring and the shaft shoulder increases correspondingly to the increase of the interference, but on the contrary, the relative deformation (i.e. displacement amplitude) between the bearing and the shaft shoulder contact surface decreases correspondingly to the increase of the interference. Therefore, it not only guarantees that there is no gear shaft material plastic deformation in the stationary state, but also enables the gear shaft to have the sufficient contact pressure to transmit the effective torque when the interference between the gear shaft and the bearing increases to the appropriate value, which can effectively reduce the fretting wear of the gear shaft shoulder.

Abstract:The combustion processes of a diesel engine operating at low speeds and low loads with different EGR rates were investigated. The CHEMKIN-Ⅱ chemistry solver was integrated into the KIVA 3V Release 2 code and a reduced n-heptane kinetics mechanism was employed as the surrogate of the diesel oxidization mechanism to model diesel combustion. Combined with the experimental data, simulations and analysis were performed for EGR rates sweeping from 0% to 60% while the injection timing was unchanged. The results have shown that the combustion phase is retarded obviously with high EGR rates. The combustion temperature is decreased and the combustion path avoids the high NOx formation regions. The NOx emission of the case with EGR 60% is reduced by 93.5%. But combustion path with high EGR rate does not avoid the high level soot formation regions and the diluted air is unfavorable to the oxidization of the soot. So the soot emission is much higher.

Abstract:Traditional analysis of the leaf spring applied only a simplified mechanical model without considering the friction between the leaf springs. In order to do better in designing the leaf spring with variable cross sections, this paper firstly constructed a parameterized model of the taper leaf spring, and then applied the contact theory to add contact element to simulate the friction between the leaf springs in the FE analysis. After these steps, the assembly of the prestressed, the stiffness, and the damping ratio could be achieved. It shows that the analysis of the performance of taper leaf spring based on FE contact analysis can reflect the actual situation more comprehensively after comparing the results with those calculated in traditional ways and those recommended by industry.

Abstract:A dynamics model of passenger car with seven freedoms considering lateral-load transfer rate was set up to deal with roll stability. The constructed model proves to be rational through vehicle road tests. According to the model, the simulation of steering wheel angle step input with different speeds was conducted, and the factors of roll stability were analyzed by the construction parameters and speed. The simulation result of Matlab shows that the driving axle of the passenger car is the dangerous axle, and when the speed or steering angle exceeds the threshold value it lifts off firstly. The roll stability of the passenger car can be promoted by enlarging track, reducing the center height of sprung mass and enhancing suspension roll stiffness.

Abstract:Route guidance can effectively solve the increasingly crowded urban traffic problem. In this paper, a research on multi objective path guidance based on increment searching was presented. Firstly, the graph theory method was used to abstract complex road networks to weighted graph that consists of points and lines. Then, a road network model was established by introducing multi objective optimization variables. Secondly, a heuristic search algorithm based on incremental searching was proposed to achieve vehicle dynamic route guidance. This algorithm combines with the global planning and local dynamic re planning. Finally, simulation results show that this method can effectively solve the vehicle real time dynamic route guidance problem in complex road networks.

Abstract:When the existing fault diagnosis methods are applied to an aircraft with a large number of components associated with each other, there appear space explosion problems in those diagnosis methods based on fault tree analysis (FTA), and the difficulty in sorting the training samples in methods based on neural network. This paper proposed a scheme that integrates the fault tree with BAM neural networks, in which all the failure modes of a system are summarized with the fault tree, sorting out the necessary training samples for the BAM neural networks. On this basis, fast and accurate aircraft fault diagnosis can be achieved by applying BAM neural networks. The experiment evaluations show that the proposed method has better scalability, and the average fault-judging rate is improved by 20%.

Abstract:The calculation of the former 5 layers stratified media theoretical model of HBC (Human Body Communication) takes too much calculation resource and time. To improve this condition, a simplified theoretical model of HBC based on the theory of waveguide on stratified media was proposed. According to the calculation results of theoretical and numerical models, attenuation constants in 5, 4 and 3 layers are consistent with each other, which is far from the results of 2 layers model. In conclusion, the model of 3 layers has been proved to maintain a balance between precision and efficiency in both theoretical and numerical approaches and can be used as the simplified theoretical model of HBC. The calculation time of the simplified theoretical model is just 0.215 times of the former 5 layers model without losing accuracy, which improves the efficiency of calculation by nearly 5 times. The simplified theoretical model is useful for the fast evaluation of the propagation mechanism of HBC signal.

Abstract:Methylene blue (MB) doped silica nanoparticles (MB-SiNPs) were synthesized in the water-in-oil microemulsion. By optimizing the concentration of MB doped in the silica matrix, the near-infrared fluorescent MB-SiNPs with strong fluorescence were obtained. Then, the feasibility of MB-SiNPs for cell labeling and tracking in vivo was studied. The cell viability assay of Hela cells in the presence of MB-SiNPs was performed by using MTT assay, and the result indicated that, as the concentration of MB-SiNPs was 1 mg/mL in medium, the cell survival percentage was 80%. The distribution of MB-SiNPs in Hela cells was assessed by laser scanning confocal microscopy, and the result showed that MB-SiNPs entered cells easily and mainly located in lysosomes. In vivo fluorescence imaging of MB-SiNPs after tail vein intravenous injection showed that the whole body of the mice emitted NIR fluorescence and most of the MB-SiNPs were accumulated in some organs, such as liver and spleen. All the results demonstrated that MB-SiNPs could be used for cell labeling and in vivo imaging.

Abstract:With the increasing application of Fe3O4 nanoparticles, it is necessary to investigate their safety to human cells. It has been revealed in this study that the colony-forming ability of HeLa cells is not influenced by Fe3O4 nanoparticles, indicating that Fe3O4 nanoparticles do not exhibit cytotoxicity to those cells. However, Fe3O4 nanoparticles significantly inhibit the colony-forming ability of XPF cells, which contain mutated XPF gene and possess a deficient nucleotide excision repair (NER) pathway, with a concentration dependent pattern. Our data illustrate that Fe3O4 nanoparticles are cytotoxic to XPF cells. HeLa cells and XPF cells were incubated with Fe3O4 nanoparticles containing cell culture media. The mRNA level of several genes, which were involved in cell cycle regulation or the cellular response to stress, has been detected by RT-PCR assay. Only significant elevated mRNA level of CHEK1, RPA1, RPA2 and RPA3 has been observed in XPF cells. The results imply that Fe3O4 nanoparticles are not suitable for patients with any mutated NER gene.

Abstract:Microorganisms were obtained by means of separation and purification experiments from waxy oil production wells in Daqing Oilfield. The paraffin-degrading strain and the biosurfactant-producing strain were identified as Bacillus sp.. As the indicator of the paraffin degradation rate, the paraffin-degrading strain and biosurfactant-producing strain were added in different proportions. When the optimum proportion was 5∶3, the paraffin degradation rate could reach 59%, the paraffin prevention rate could reach 57.4%, the reduction rate of oil viscosity was 44.7%, the oil freezing point reduced by 3.4 ℃, and the reduction rate of culture surface tension was 46.5% after 7 days. Microbial paraffin-removal technology was used for paraffin removal in Wells 12-36, 13-39 and 14-43 in Yushulin Zone Daqing Oilfield. The results indicated that the daily crude oil increased by 41.2%, hot washing cycles prolonged from 40 d to 149d and washing numbers reduced by 4 times in Well 12-36, the daily crude oil increased by 33.3%, hot washing cycles prolonged from 45 d to 158 d and hot washing numbers reduced by 5 times in Well 13-39, the daily crude oil increased by 37.5%, hot washing cycles prolonged from 30d to 122 d and hot washing numbers reduced by 5 times in Well 14-43.

Abstract:HJ 1A/1B satellite data in 2010 were used to extract wetland vegetation of East Dongting Lake. Based on the same period's MODIS13 (Moderate Resolution Imaging Spectrometer) data production, the annual maximum value and average value of the EVI (Enhanced Vegetation Index) were synthesized. Vegetation spatial distribution and its biomass were discussed by combining the above indexes with the elevation figure of East Dongting Lake. Moreover, the most suitable growth area of vegetation was assessed from hydrological factors and vegetation growth characteristics, which will provide theoretical guidance for the protection of the vegetation diversity and the restoration and utilization of the vegetation resource in East Dongting Lake. All these proved that long water flooded time in the regions of low elevation was harmful to the growth of moss grasses. The results indicated that vegetation spatial distribution and its biomass had great correlation with the elevation and water environment in East Dongting. The shelter forests, whose water demand is not high, grow in the area more than 30m in height and away from the water, while reeds grow well in the area above 27m elevation and near waters, and moss grasses are suitable to grow in the regions ranging from 23m to 27 m.

Abstract:Commercially activated carbon was treated with 1mol/L nitric acid, 1mol/L sulfuric acid and 1mol/L hydrochloric acid respectively. The physicochemical properties of these modified activated carbons were described with Boehm titration, Fourier transformed infrared spectroscopy (FTIR) and BET surface area measurement. Fixed-bed adsorption experiments were conducted under the same experimental conditions at 283K, where toluene was activated as adsorbates. Adsorption capacity on modified activated carbons was conducted, combining the calculation of dynamics and adsorption energy. The results have shown that the total amount of acid groups increased after acid modification and the pore size distribution is different from the unmodified activated carbon. The adsorption capacity of toluene on acid modified activated carbon shows the following order: N-AC，S-AC，AC， Cl-AC. The pseudo-second-order kinetic equation is better than the pseudo-first-order kinetic equation to describe the adsorption process of toluene on the modified activated carbons. Acid modification can increase the percentage of micropore and enhance the rate of adsorption. With the increase of adsorption energy, it is hard for the modified activated carbons to join toluene.

Abstract:In order to overcome the slow convergence of the segmentation method based on the Chambolle's dual iterations to achieve high precision segmentation, we proposed an improved dual iteration of Chambolle to solve one of the sub-problems arising from the two-phase piecewise constant Mumford-Shah model. By using the LFA of the Chambolle's dual iterations and a modified dual iteration respectively, we have proved that the proposed algorithm is very reasonable. Experiment results have shown that, for the two-cell image and the dot256 image, when the accuracy of the termination criterion is higher, the number of iterations of the proposed algorithm is less, and it converges faster.

Abstract:To investigate the propagation characteristics of ultra-wideband (UWB) signal in forest land environment, a channel model for forest land (orchard) was proposed on the basis of frequency-domain measurements according to the UWB frequency regulation of China. The modified S-V model was exploited for the channel modeling. A quasi-Gaussian window with Gaussian transition band was used to extract the measurements that satisfy the UWB frequency regulation of China in the post-processing of channel modeling. Furthermore, a wavelet analysis based cluster identification algorithm was proposed for the time-domain measurements. The channel parameters were extracted on the basis of statistical approach. Simulation results have shown that the proposed forest land UWB channel model has similar delay spread characteristics and similar number of main paths with the measurement data.