Abstract:Perforated channels and upright stiffeners were employed in the diagonal unbonded steel plate brace encased in reinforced concrete panel, referred to as panel buckling restrained brace (panel BRB), to improve the punching shear capacity of panel. Quasi-static tests were carried out to investigate effects of constructional details on the hysteretic behavior of panel BRBs. Punching shear design methods for the panels were examined based on test results. Tests reveal that the perforated channels can avoid the punching shear failure of panel and greatly decrease the punching shear cracks, as compared with the additional steel bars used around the brace. Besides, compared with flat stiffeners, the upright stiffeners used in a brace can decrease the width of gap between the panel and the brace near the tips of stiffeners and therefore decrease the punching shear forces applied to the panel by the ends of brace. Punching shear failure of panel or tension fracture of brace occurred at the end of tests. All specimens exhibited stable hysteretic behavior before the failure of panel BRBs occurred. The punching shear design methods for the panels were proposed based on the possible failure modes of panels.

Abstract:Theoretical derivation and finite element method were developed in this paper to study the fire resistance performance of mobile house. First, based on the equivalent principle of the critical temperature,the structural deformation curve was simplified as elastic and vertical segments instead of the original elastic-plastic model. Then, deformation formula of the elastic segment was obtained by theoretical derivation, and the method of determining the dividing point was also provided. To this end, the critical temperature formula of frame under fire was obtained. Finally, the fire resistant performance of the entirety house structure and the single frame were analyzed and compared through finite element method. It shows that, the fire resistance performance of the entirety house structure is similar to single frame structure, the number of frame have little effect on the fire resistant performance of entirety house, and the most unfavorable fire location is the middle room.

Abstract:Full-scale experiments were carried out to investigate the static responses of light-gauge slotted steel stud walls with different web heights subjected to uniformly distributed transverse loading. The failure modes for the walls were depicted. The influence of the web height on the static behaviour of this new kind of light-gauge steel stud walls was analyzed. By means of ABAQUS, finite element model was built to numerically investigate the bending behaviour of the full-scale light-gauge slotted steel stud walls. The analysis results were benchmarked against the experimental ones. It was concluded that the gypsum board can prevent the studs from overall buckling. The stud wall with web height of 150 mm failed in shear mode at the support and buckled in both the local and distortional mode at the mid span, while the stud wall with web height of 100 mm only failed with local and distortional buckling at the mid span. When there is no window hole, the slotted steel stud wall with a web height of 100 mm can resist the wind loading in China for the building with the height lower than 50 m.

Abstract:In order to treat the small town sewage wastewater with high efficiency, energy saving and low power consumption, a combined coagulation cloth media filtration-anaerobic filter／trickling filter system was established at experimental condition. Via the experimental optimization of equipments and materials, the optimal operation parameters of each part, especially the nitrogen removal ability during the start-up of the trickling filter had been investigated. Experimental results showed that at 1 mL／L fly ash coagulant dosage, 54％ removal of COD_cr and 81％ of TP would be removed by the combined system. The optimal hydraulic loading was 15 L／d and the optimal reflux ratio was 150％, which would guarantee the effluent ammonia, COD_cr, TP reach A standard.

Abstract:To develop a shortcut nitrification process for treating anaerobic digested piggery wastewater with a high ammonia concentration, a sequencing batch reactor (SBR) was introduced, and the temperature, ammonia nitrogen loading rate (Rnl) and aeration time were investigated as the significant influence factors of the shortcut nitrification. The shortcut nitrification process could be established in the SBR at 28 ℃ or 15 ℃ with the identical dissolved oxygen (DO), ranged from 1 to 2 mg·L-1. But the ammonia removal and nitrite accumulation rate Rna were decreased from 71.1％ and 96.7％ to 52.8％ and 85.4％, respectively, when the temperature was dropped from 28 ℃ to 15 ℃. Though the ammonia removal rate was decreased to 48.6％ since the Rnl had been increased from 0.56 to 2.18 kg·m-3·d-1 at 28 ℃, a Rna as high as 96.8％ was obtained, indicating that an excellent shortcut nitrification occurred in the SBR. To obtain a superior ammonia oxidation with a higher Rnl, extension of aeration time would be supportive. But an excessive aeration could result in an increase in nitrate and a decrease in Rna, which was unfeasible for the shortcut nitrification process in the SBR.

Abstract:To better separate biological sulfur from denitrifying sulfide removal (DSR) process, we determined a new method by researching on the distribution characteristics of biological sulfur in this process system, Zeta potential, particle size distribution, scanning electron microscope and energy spectrum analysis. The results showed that the biological sulfur in the effluent and sludge accounted for 65％ and 35％ of the total sulfur production, respectively. S content of biological sulfur particles is no less than 60％. Zeta potential value is approximately -20 mV (between ±30 mV); Biological sulfur particles are spherical with rough surfaces, with many functional groups on the surface such as polysaccharide and proteins. The above biological properties indicate that it has characteristics of colloid. The biological sulfur flocculation rate is approximately 99％ when using cationic coagulant to separate biological sulfur. Coagulation is an effective method of separating biological sulfur form (DSR) process.

Abstract:According to the characters of HABS industrial wastewater of high pH, high COD and high concentration of sulfite, a pilot reactor with catalytic oxidation-Fenton combined treatment process was built, and the pilot scale experiments were employed to discuss the optional parameters. A pilot scale is 5 t／d. After optimized, the optimal optional parameters in catalytic oxidation stage were pH 8, aeration rate 50 m³／h, HRT 90 min. The optimal optional parameters in Fenton stage were dosage of H₂O₂(30％) 1.00 mL／L. The effluent quality can meet the first class requirements of Sewage Discharge Standard in GB8978—1996, which suggests the process is economical and feasible.

Abstract:Blockage in pressure pipelines has become a serious issue in the world. According to the basic principle of auto-oscillation theory, the simplified model is put forward for the numerical simulation of blockage detection. Based on the theory of transient flow, the governing equations of transients in a pipeline including blockage are established with the adoption of Dirac delta function. Non-dimensionalizing and linearizing the governing equation, the equations will be simplified. An analytical solution has been deduced under the fixed boundary conditions. By Fourier series analyzing, the amplitudes of each harmonic component in different periods are calculated, and the damping exponent of each harmonic component can be obtained. The results show that the blockage damping is direct ratio to the flow rate of pipe, and the location of damping has the cosine relation with damping parameters, so the location and magnitude of blockage can be fixed if two blockage damping parameters are known.

Abstract:Because of insufficient research on single well groundwater heat pump systems, a physical simulation experiment table has been set up to study the flow and heat transfer law in these systems. Experimental research on building load variations has been carried out. The results show that in the same experimental conditions the absorption quantities of standing column well (SCW) are only 50.3％ and 45.9％ of pumping and recharging well (PRW) and pumping and recharging well filled with gravel (PRWFG) respectively. In addition, the radial thermal influence scope of SCW is less than 186.5 mm. However, the heat absorption quantities of SCW, PRW and PRWFG reduce to 51.0％, 31.6％ and 19.5％ individually, when the flow rate of outlet water drop from 0.54 m³／h to 0.315 m³／h. Thereby the load capacity of SCW is the least one in these three systems. However, the variation of the flow rate of outlet water can impact on SCW more significantly. It is more obvious that increasing the flow rate of the outlet water can improve the load capacity and the thermal influence scope of the thermal source wells. Thus, the load capacity of thermal source wells can be increased.

Abstract:In order to study the evolution of the flow pattern in a phase-transition vapor-liquid two-phase flow in a horizontal pipe, numerical simulation based on volume-of-fluid (VOF) model and the Reynolds stress turbulence model (RSM) was performed. The characteristics of convective heat transfer, pressure drop and evolution of flow patterns in the simulated horizontally pipe-flow were analyzed. It was obtained that the VOF model and RSM model can be used to simulate bubble flow, stratified flow, wavy flow, slug flow and annular flow. The simulated two-phase flow patterns are in agreement with the Mandhane flow pattern map. Furthermore, the simulated heat transfer coefficient and pressure drop are also in good agreements with the existing correlations.

Abstract:A novel algorithm, which comprises with convex hull construction algorithm and robot controller is proposed for robot path planning based on complicated local data in robot’s autonomous navigation system. First the algorithm searches out the local optimal path from the robot’s current position to its target according to the local obstacle data. When the robot can not reach the final target directly, a temporary target point in the optimal path will be set to instruct the robot to avoid the obstacle and reach the final target. Next, a controller is design based on attractive force field and repulsive force field to control the robot’s motion, the combined effect of both attractive force field and repulsive force field drives the robot move toward the objective acquired from the optimal path and avoid obstacles at the same time. The experiment results show that this method can provide a better planning path compared with traditional path planning algorithms such as artificial potential field (APF), the wall-following (Bug) and the artificial moment method, and it has a fast reaction speed that is suitable for practical applications.

Abstract:To investigate the influence of the vertical component of impulse-type strong earthquakes on the dynamic responses of ultra high-rise buildings, spectral elements are applied to analyze the wave effect of a simplified computational model for the main structure of typical frame core-wall structural system excited by the vertical component of impulse-type strong earthquakes. Then, the dynamic time-history results from this method are compared with those from classical vibration mechanics. In the wave propagation analysis, the spectral element using the Timoshenko’s beam theory is developed to reflect shear deformation in mega horizontal transverse link members. The axial responses of vertical members are modeled by rod spectral element and the dynamic wave equilibrium is modified to account for the time delay as earthquake waves propagating through structures. The results from examples analysis indicate obvious fluctuation of axial force in vertical members and significant relative displacement between core walls and external mega columns. Hence, shear problem in transverse link elements cannot be ignored. Such shear-induced damage would be nonlinearily coupled with the subsequent horizontal component of impulse-type strong earthquakes, requiring special attention.

Abstract:Series of one-dimensional electro-osmotic laboratory tests were conducted in a self-made tank to investigate the impact of current intermittence on electro-osmotic effect. The tests were divided into two stages. In the first stage, time ratio of power on and off was fixed to study the effects of different power on periods, which were also compared with the result of continuous conduction. In the second stage, the power on period was fixed to study how different time ratios of power on and off affect electro-osmotic process. Currents and drainages were monitored every certain time during the test, while the distributions of shear strength, water content were measured after the test. The results suggest that the testing time possesses key influence on the effectiveness of current intermittence and the distinction of electro-osmotic effects obtained. With appropriate power on period and time ratio, current intermittence can result in lighter electrode corrosion and enhance electro-osmosis efficiency excessively. Finally, reasonable explanations of the different results in existing literature were given, and it is recommended to employ current intermittence for engineering application of the electro-osmosis technique, with the optimal power on period and time ratio of power on and off being 1-4 h and 2.0 respectively.

Abstract:To evaluate the rutting resistance differences of indoor samples and pavement cores, Rotary Loaded Wheel Tester (RLWT)was used to acquire rutting deformation, and rutting resistance of indoor samples and pavement cores was researched from the macro perspective. Industrial CT was utilized to obtain asphalt mixture sectional scanning images, the distribution along the depth direction of coarse aggregate particles and area porosity of indoor samples and pavement cores from the micro angle were explored. The results show that the air porosity of the two kinds of samples vary greatly due to the different manners of compaction, leading to the significant discrepancy in the capability of rutting resistance. The uniformity of the distribution along the depth of coarse aggregate particles and area porosity of pavement cores are poor, and the average area porosity and area porosity in the upper part of the pavement cores are obviously greater than those of indoor samples, which proves the accuracy of the macro research from the micro perspective.

Abstract:The effluent quality of combined process containing O₃-BAC treatment between sedimentation process and dissolved air flocculation(DAF) process for the treatment of East Taihu Lake raw water were compared. The results showed that the removal efficiency of turbidity by DAF was 10.1％ higher than that by sedimentation process, and the effluent turbidity was stabled at 1 NTU or less after the treatment of the O₃-BAC. Compared with the sedimentation process, the CODMnand DOC removal efficiencies of DAF were increased by 5.4％ and 1.6％, respectively. The CODMnand DOC were stabled at 0.5-2.1 mg／L and 0.3-2.0 mg／L after O₃-BAC process respectively, while the organic concentration could not reach to effluent standard after conventional treatment. O₃-BAC process played a dominant role in the decrease of fluorescence intensity, while conventional treatment process had only a slight or no effect on the removal of fluorescent material. The experimental results indicated that the DAF was slightly better for algae removal efficiency than sedimentation process. The concentration of diatom activity and chlorophyll decreased to 0 and cyanobacteria still retained part of the activity after advanced treatment.

Abstract:The pilot-and lab-scale reactor was constructed, respectively, to evaluate the influence of ammonia and nitrite on the performance of Fe and Mn removal. The results of pilot-scale filter indicated that the nitrite concentration of 0.1,0.2,0.3,0.7 mg／L, had no effects on Fe and Mn removal, as well the ammonia concentration of 1.2 and 2.2 mg／L. However, the ammonia concentration about 4.5 mg／L would inhibit the Mn removal, resulting in higher Mn in effluent than requirements; The lab-scale SBR experiments demonstrated that the activity of Mn oxidizing bacteria(MnOB) was enhanced by nitrite, but inhibited by ammonia, which showed the importance of nitrification in biological removal of Fe, Mn and ammonia process, especially in the period of start-up.

Abstract:To reduce the probability of aircraft cargo door opened accidently caused by abnormal stress, the dynamic characteristics of multi-linkage lock mechanisms with kinematic pairs clearance are studied in detail. The equivalent joint clearance link (the length is e) is used to describe the influence of kinematic pairs clearance. Meanwhile, the dynamic analysis model of multi-linkage lock mechanisms is built based on the Lagrange kinetic equation and the screw theory, and the procedures programmed by MATLAB are used to solve and analysis the model. Results indicate that the kinematic pairs clearance has a bigger influence on angular velocity of the rod, angular acceleration of the rod, driving moment and hinge binding kinematic, and the greatest influence appears near the singular configuration. While e is 10 μm, its impact on dynamics of the multi-linkage lock mechanisms is small, however while e is 100 μm, the impact is enhanced obviously.

Abstract:An adaptive unsharp masking filter is proposed to enhance the details blurred in the depth map filtered. Firstly, the color image is used as guided image in joint bilateral filter to recover the lost region and reduce the noise. Then a mask is extracted by subtracting a low-pass filtered depth map from the bilateral filtered depth map, which effectively overcomes the shortcoming of traditional method that amplifies high-frequency noise. Finally, according to degree of blur, the spatial importance is adaptively added to the depth map filtered. Experimental results show that the proposed method performs better in enhancing the details, reducing noise and recovering the lost region of depth map.

Abstract:To solve the problem of star extraction on the condition of strong interference, a star extraction method based on edge detection+selection for star pixels was proposed in this paper. An edge detection algorithm to segment the star image is first utilized, and then each pixel is marked. Finally, self-adaptive threshold to select the object pixels of each star is used. Also, the pixel labeling algorithm is improved, and before the pixel of target is labeled, the connectivity of its neighbors is examined so that all of the pixels of the same star only have one mark and the processing efficiency of star image is improved. Experimental results show that the method has better robustness to strange interference, higher speed and accuracy. The improved method can distinguish sensed stars more quickly, and may be more convenient for engineering applications.

Abstract:To recognize driving mental fatigue efficiently, this study constructs a recognition method based on ECG. The method proposes hierarchy partition of state of driving mental fatigue by using driving behavior performance as objective evaluation indexes. Meanwhile, taking 6 indexes of HRV as fatigue recognition characterization factors and BP artificial neural network model, this paper establishes the recognition model for state of driving mental fatigue. Finally, according to examples, the mental fatigue is divided into two classifications. Collecting 4 hours continual driving behavior performance and ECG data from 10 drivers to test the model, the result shows that the average recognition accuracy rate is between 71％ and 80％, and the average accuracy rate is 73％. The combination of BP neural network model and HRV indexes could recognize fatigue effectively.

Abstract:To solve the multicommodity flow problem in traffic network, this paper analyses the multicommodity flow traffic network with same cost, and builds the composite parameters and composite indicators on account of the successive shortest path algorithm and the Ford-Fulkerson algorithm. Based on the corresponding calculation rules of composite parameters and composite indicators, this paper builds a minimum cost flow algorithm for multicommodity flow traffic network and the feasibility of this algorithm is verified by an example. This algorithm provides the basis to solve the problem of multicommodity flow minimum cost flow with same cost which is quite widespread in the field of transportation.