Abstract:To know the function of protective measures for reticulated shell subjected to internal blast loading, a fine finite element model for Kiewitt8 single-layer reticulated shell which contained reticulated shell member, purlin hanger, purlin, rivet, roof boarding, wall and ground was established by using finite element software ANSYS/LS-DYNA. The effect of reinforcement for reticulated shell member, selection of roof boarding and openings in the wall was studied by using ALE (Arbitrary-Lagrange-Euler) algorithm. The results showed that by selecting the outer-loop members to reinforce, choosing light roof boarding or thin roof boarding, increasing the opening rates and the height of position, and reducing the opening spacing, the dynamic response of the reticulated shell under internal blast loading could be reduced effectively.

Abstract:To accurately determine the bearing capacity of reinforced concrete slabs, based on the yield hinge line theory and segment equilibrium method, this paper presents two failure criteria to determine the limit carrying capacity and displacement of the slabs, which consider the membrane effect. The calculated results were compared with the test results. The results show that the calculated limit carrying capacity of the slab is agreement with the test result, and the calculated limit displacement is relatively conservative compared with the experimental result. According to the mechanical analysis, the model explains the failure mechanism that the limit carrying capacity of the square slab is lower than that of the rectangular slab under the same deflection.

Abstract:This paper develops a cellular automata (CA) technique for predicting the failure modes of single-layer latticed cylindrical shells to address computing time cost and explore computing results’ further application. Firstly, finite element analysis gives out the failure modes of the single-layer latticed cylindrical shells under harmonic loads and TAFT seismic waves. Then, two CA numerical modes are established: the dynamic instability modes of shells under harmonic ground motion, described by the normalized finite element node displacements; the strength failure mode under TAFT seismic waves, described by the logarithmic strain energy density of node domain. Moreover, the concept of node domain similarity is proposed and the corresponding criterion is established to match the node domain similarity between shells. Finally, the CA technique is formed to predict the dynamic instability modes and the strength failure modes of objective shells, based on the failure modes of base shells. The predicted results validate the CA technique, which could be a new way for analyzing shell structures.

Abstract:To evaluate seismic risk and identify critical pipelines of water supply system, water supply index(S), pipeline update profit(U) and pipeline break consequence(B) are set up to describe system seismic performance, and the graphical iterative response analysis of flow following earthquakes (GIRAFFE) based on Monte Carlo simulation is applied to the hypothetical water supply system for peak ground velocity vG=50 cm/s. The simulation result shows that the distribution of S is related to nodes’ demand pattern in the system. Calculated by running single Monte Carlo simulation, U could be used as primary indicator to identify individual critical pipelines and maximum benefit portfolio, and it is the consequence of B and pipelines’ damage probability. Updating the group with largest individual critical pipelines is not the best strategy for the system,and the system seismic performance would be most improved by updating maximum benefit portfolio.

Abstract:To rapidly identify anaerobic ammonium-oxidizing (anammox) bacteria in environmental samples, a cloning-independent method based on Terminal Restriction Fragment Length Polymorphism (T-RFLP) was proposed. Based on SILVA (R108) SSU Ref database containing 400 16S rRNA gene sequences of anammox bacteria, defined lengths of terminal restriction fragments (T-RFs) were predicted by virtual PCR and restriction enzyme digestion using suitable PCR primers (Amx368f-Amx820r) and restriction enzyme (MspI ＆ RsaI). Then the genus of anammox bacteria was identified by comparative analysis of T-RFs. The repeatability and sensibility analysis results show that the anammox bacteria specific T-RFLP analysis is a reliable tool to rapidly assess the complexity of anammox bacteria in environmental samples.

Abstract:To investigate the relationship between microbial properties and membrane fouling, an anoxic-aerobic membrane bioreactor (A/O-MBR) was established and run at room temperature. The techniques of Terminal Restriction Fragment Length Polymorphism (T-RFLP) and Atomic Force Microscope (AFM) were used for analyzing the role of microorganisms for membrane fouling in different stages, and the three-stage model was applied to study the development process of membrane fouling in a whole cycle. The results showed that the process of MBR membrane fouling could be divided into three stages. The solid or dissolved materials attached to the membrane wire surface and the membrane pore were the main reason for the lower flux. The microbial community structures were different and changed with the deepening membrane fouling in the Aerobic mixture, the Cake layer and the membrane wire surface. With the increasing of the membrane pressure, the succession of dominant populations of the microbial in the Cake layer is: Rhizobiales Bacterium →Burkholderia sp.→Uncultured Nitrospira sp.→Thiothrix Eikelboomii →ZoogloeaRamigera→ Betaproteobacterium, and ZoogloeaRamigera is greatly related to the viscous material on the surface of membrane.

Abstract:To overcome the drawbacks of high bulk density and bad applicability, in this study, straw ash was used as an additive to make unburned ceramsite which could be applied to sewage treatment. This method not only broadened the application of the unburned ceramsite and promoted unburned process, but also provided an economical and rational way to dispose fly ash and straw ash from power plant. The activity-excitation mechanism of fly ash, the function of primary components and the phase composition of ceramsite were studied in this research. The optimum process parameters were:5％ NaOH solution pretreat fly ash, and the ratio of the components were fly ash of 58.11％, calcium oxide of 4.84％, cement of 29.05％ and straw ash of 8％; The main characteristics index of ceramsite were shown as follows: bulk density of 785 kg/m³, specific surface area of 11.1 m²/g, broken rate of 2.3％. The ceramsite was tested on leaching toxicity and basic properties, and the results indicated that it was a proper way to make functional ceramsite of good property used in sewage treatment with straw ash as an additive raw material, and it achieved the purpose of economic energy conservation and waste treating.

Abstract:In view of the aesthetic problem and potential threat to safe drinking water caused by invertebrates, a series different depth of sand beds were located under granular activated carbon (GAC) media in five pilot-GAC filtration (GACF) columns to restrict invertebrates’ penetration into the distribution system. During the study period of 10 months, 7 groups of invertebrates (rotifers and crustaceans as the predominant species) were detected in the filtrates of the five GACF columns. The experimental results indicated that invertebrates could be removed effectively with the added sand beds compared with the sand bed-free GACF column. The mean abundances of invertebrates decreased significantly with the increase of the depth of sand beds. The 46.6 ％ of rotifers and 85.5％ of larger invertebrates (size>200 μm) could be removed from the filtrate. Sand sizes had a greater impact on rotifers removal than larger invertebrates. Also increasing removal ratios of particle matter were detected with the sand beds added. Further data analysis showed that there was significant correlation between the mean values of particle counts and abundances of invertebrates in the filtrates.

Abstract:To improve the assembly precision of mobile phone camera, a small-sized parallel manipulator (SSPM) used for precise assembly was developed, and a calibration test and mechanical error analysis were conducted. First, an error model and the forward-inverse kenametic model were derived using numerical method, and the connection problem between the error model and the kenametic model was studied. Second, a calibration procedure was designed and a calibration test was conducted on coordinate measuring machine (CMM). Finally, an analysis on the error sources of SSPM was conducted from the mechanical view, the effect of SSPM’s structure on the gap error was analyzed, and a repeatability test of SSPM was conducted to represent the gap error. After calibration and mechanical error control, the maximum displacement error decreases from 0.345 9 mm to 0.012 1 mm, the maximum angular error decreases from 0.007 3 rad to 0.001 1 rad, and the repeatability of SSPM is 0.004 8 mm. Experimental results show that the calibration and mechanical error control method on SSPM can effectively improve the accuracy of SSPM.

Abstract:Aiming at the present situation that needs to develop a code review tool for assembly codes, this paper studies the procedure of manual code reviews and proposes a method to detect defects in assembly codes based on static analysis. After the control flow linearization, compiler patterns are used to solve indirect jumps, and node cloning is used to recover the control flow of the delayed branch. In the construction of inter-procedural control flow graph, the recursive function is in-lined by means of a call trace with limited depth. The prototyping tool for ADSP SHARC assembly codes is realized finally. Experimental results show that the tool can effectively detect defects in loops, registers, and memory accessing.

Abstract:A two-lane cellular automaton model was developed to analyze traffic flow considering influence of emergency vehicle. The affected areas of emergency vehicle and the give way probability of general vehicles was introduced to modify lane change rules. Space-time diagram of different densities and fundamental diagrams under different parametric conditions were given by numerical simulations. The simulation results indicate that the parameter settings for affected areas of emergency vehicle only improves traffic volume with density in the range of 0.08 to 0.18 but it makes the emergency vehicle speed increase significantly in larger density. And the give way probability has an important impact on lane change times with density greater than 0.8. The study found that appearance of emergency vehicles promoted traffic flow of lower density more balanced and the interference on traffic flow of higher density was limited.

Abstract:To research a fast and nondestructive testing method of compaction quality of gravel soil subgrade, to evaluate the uniformity of compaction and to improve the gravel soils roadbed compacted quality, differential settlement and deformation modulus were measured by adopting level measurement and PFWD on designated points of gravel soils roadbed. The relationship of differential settlement between deformation modulus Evd is established. The compaction test standards of Evd base on different request of differential settlement are put forward. The compaction quality was evaluated by compaction tracking detection, the roadbed top 3D model of deformation modulus was established by the high density detection of gravel soil subgrade deformation modulus and the roadbed compaction uniform index defined. The compaction uniformity and the weak area of compaction were evaluated. The results of the study show that, according to the relationship between the differential settlement and Evd, the PFWD nondestructive testing can quickly and effectively evaluate gravel soil subgrade compaction condition, the homogeneous degree index can be used to evaluate the roadbed compaction evenness, the gravel soil subgrade compaction uniformity can be improved by adding compaction to the weak area.

Abstract:This paper proposes an actuator fault diagnosis approach based on unknown input observers for the attitude control system of satellite. More specifically, by considering an actuator fault as the unknown input vector, an unknown input observer is designed so that the residual is sensitive to the other faults while insensitive to the appointed one. In this work, the design of unknown input observer is formulated as a set of linear matrix inequality (LMI), which can be solved by the LMI toolbox conveniently. Finally, the proposed approach is applied to the satellite attitude control system. Simulation examples illustrate the presented method is able to detect and isolate the actuator fault effectively.

Abstract:To shorten the research and development period and to lower the complex of design of cold spray system, a commercial software Star-CCM+(Version 6.04) is used to calculate the state of gas flow, the relationship between exit temperature and the structure of gas heater, flow rate and heat input. The results indicate that a steady temperature can be reached for the whole gas heater. The velocity of the gas changes little in the tube. There exists a large temperature difference between resistance tube and the gas. An optimized heater structure can increase the efficiency of heat exchanging. To ensure a high efficiency, the length of the resistance tube must be long enough; the larger the center pitch, the higher the exchange efficiency. The suitable diameter (8-12 mm) is also required for the resistance tube.

Abstract:In space attack-defense system, relative position and velocity estimation between intercepting satellite and target satellite is very important for orbit designing of intercepting satellite. In this paper, relative navigation is researched under the condition that orbit of target satellite is elliptical orbit and that the intercepting satellite has orbit maneuvering. Firstly, relative motion equations are derived with elliptical orbit of target satellite, and measurement equations are developed according to the geometric relation of measurement. Then the accelera-tion of intercepting satellite is introduced with its error, and the improved EKF algorithm is designed to increase navigation accuracy. Finally, the numerical simulation results verify the validity of this navigation method and show higher navigation accuracy.

Abstract:To explore the applicability of extreme value distribution models, known as type I, II and III extreme value distribution, to the extreme wind velocity evaluations of project site during the return period, and according to the wind speed distribution model commonly used in engineering fields, Monte Carlo simulation method is used to produce the pseudo wind speed samples, respectively fitting exponential distribution, normal distribution, Rayleigh distribution, Weibull distribution, lognormal distribution and the generalized extreme value (GEV) distribution. The maximum likelihood parameter estimation method and probability weighted moment method are used to estimate the parameters of the type I, II and III extreme value distributions. A comparative study of different parameter estimation methods for every extreme value distribution has been done by comparing with the theoretical extreme value distribution of the pseudo wind speed. The analysis shows that the maximum likelihood parameter estimation method is optimal for the type I, II and III extreme value distribution. The extreme value wind velocity evaluations of the pseudo wind speed samples during the return period are sensitive to the parent distribution of the pseudo wind speed samples, so different parent distributions of wind speed should be targeted to the selection of different type of extreme value distribution.

Abstract:The traditional faulting distress detection method is a manual detection method, which is inefficient, less reliable and dangerous to use. To overcome these shortcomings, a new automatic detection method based on statistics values of vertical acceleration was proposed. Firstly, noise reduction was applied to acceleration signals by 5 layers Daubechies wavelet, acceleration sequence was put forward from the acceleration-gray map and a new joint location method based on the joint periodicity in the acceleration sequence was obtained. Secondly, three statistic parameters were adopted to analyze the acceleration variation near the joint, which included the position distribution of peak acceleration values (gm) as well as the accumulative mean of acceleration values (ge) and the accumulative absolute mean of acceleration values(ga) at the same position on each slab from the acceleration-gray map. Test results show that the position distribution of peak acceleration values(gm) on slabs is similar to random distribution, peak acceleration values have no relation with faulting distress. The position of peak values and the amplitude near each joint on curves of ge and ga have weak relation with faulting distress. The increment near each joint on the curve of ga has fair relation with faulting distress. Based on the analysis, a new acceleration statistic parameter (af) was put forward to estimate the faulting value, which had good relation with faulting distress.

Abstract:Domestic wastewater was treated by using three parallel sequencing batch reactors (SBR) at the pH of 7.9-8.0 to optimize aeration duration of partial nitrification. The partial nitrification was achieved and maintained by controlling the aeration time of t/2, t/4, t/8 respectively (t was aeration time) before appearance of "ammonia valley". Nitrite accumulation ratios were improved by 50％, 65％, 90％ respectively in the three reactors which were operated in 145 days. FISH quantitative analysis showed that the percentage of ammonia oxidizing bacteria (AOB) in the reactors increased differently. AOB and nitrite oxidizing bacteria (NOB) was 3.89％ and 0.27％ of the total bacteria respectively in No.3 reactor, which showed that AOB is the dominant bacteria in nitrifying bacteria. It is concluded that synergistic effect between the optimal control of aeration duration and the inhibition of FA would be the key factors to rapid start-up and maintain the stable nitrification.

Abstract:To reduce the network leakage effectively and determine the position of the leakage point or region and leakage volume quickly and exactly, the inverse transient leakage location technology based on genetic algorithm is proposed to realize the real-time leakage diagnosis of water supply network. First of all, the microscopic model is established as the basic hydraulic model based on inverse problem analysis. By correlation analysis of the network leakage and pressure variation, the inverse transient leakage location model of water supply network based on genetic algorithm is established. The model takes the position of the leakage point and the corresponding volume as variables, takes the minimum difference between the monitoring value and simulation value of pressure monitoring points when leakage occurs as target. By simulating three leakage modes, the practicality and effectiveness of the inverse transient leakage location model of water supply network are verified. The research provides important basis for making program of leakage detection and location effectively.

Abstract:A precise assembly and measurement system was developed and fabricated for multi-peg-holes assemble based on interference fit, in which a compliant gripping mechanism was designed to avoid the assembly jam, the force/stiffness position compensation was proposed to eliminate the fabrication tolerance deflection of 10 μm, and the ring components were precisely positioned in the assembly mold. Borescope decouple vision measurement was proposed to measure the position of assembled components in narrow and dark environment. The position information of assembled components was measured combining the information of captured image and grating rule which assembled on the linear guide driving the borescope. The experimental results show that using the developed system, the position errors of assembly were from -9.4 to 6.1 μm and the measurement errors were from -1.7 to 8.2 μm, it could meet the requirement of the precise assembly and measurement.

Abstract:A novel method combining BEMD and receiver operating characteristics (ROC) curve is presented in this paper to solve the problem that the threshold is greatly affected by personal experience when underwater image edge detection is performed using a bi-dimensional empirical mode decomposition (BEMD) algorithm. Firstly, the BEMD algorithm is employed to decompose an underwater image into several intrinsic mode functions (IMFs) and a residual. Then several IMF images are computed using combinations of the Canny detector parameters, and the image binaryzation results are generated accordingly. The ideal BEMD edge feature extraction maps are estimated using correspondence threshold which is optimized by ROC analysis. The experimental results show that the proposed algorithm is able to avoid the operation error caused by manual setting of the detection threshold, and to adaptively set the image feature detection threshold. The proposed method has been proved to be accuracy and effectiveness by the underwater image processing examples.

Abstract:For the improvement of the effect of traffic multi-step forecasts using short-term data of loop in Sydney coordinated adaptive traffic system(SCATS), on the basis of data preprocessing, traffic data and time points at time t over a sampling period of n intervals were included in the traffic state feature vector, Euclidean distance was used to measure the closeness between current traffic state and historical traffic state, the number of nearest neighbors corresponding to the minimum error of travel multi-step forecasts was selected, and the weights of k-nearest neighbors were identified by normalizing the reciprocal of the distance between traffic states, a new bi-level method of multi-step forecasting using k Nearest Neighbor(k-NN) algorithm was designed, including a multi-step forecasting method and a predictable steps on-line estimation method. The validity of the proposed method was tested with data measured from a megacity. The results indicate that the proposed method can further improve the effect of short-term traffic multi-step forecasts.