Abstract:In this paper, experiments on three roof truss models made of thin-walled cold-formed steel channel sections with thickness less than 2mm and yield strength over 550Mpa were carried out, and the failure modes and load-carrying capacities of the roof truss structures were investigated. Furthermore, FEM analysis model considering geometry and material non-linearity was established, and non-linear stability analysis was performed on the tested model. It was shown that both failure modes and ultimate load-bearing capacity were consistent with test results. Based on the experiments and numerical analysis, reasonable calculation model for such roof trusses was studied, and the design method for structural members of the trusses were presented according to related national and foreign cold-formed steel structure design codes. Moreover, an improved construction details for strengthening rigidity of the ridge joint plate was also proposed.

Abstract:Low cyclic loading test is conducted on one comparative short column and five RC short columns strengthened with BFRP and CFRP. The tests shows that failure modes, shear strength, ductility and energy dissipation are improved and increased for specimens strengthened with BFRP. In the same condition, various short columns strengthened with BFRP and CFRP give similar seismic performance. But BFRP has a good perspective for its low cost and good comprehensive mechanical properties in seismic strengthening field.

Abstract:Based on the modal perturbation method and the mode superposition method, an approach is established for vertical seismic response analysis of the prestressed bridge. Several problems met in the vertical seismic response analysis of the prestressed bridge are discussed by analyzing two simply-support prestressed bridges. Some conclusions are obtained from the numerical results as follows: ① The natural frequencies increase when the preloading is applied on the bridge. The preloading effect is mainly on the lower natural frequencies and the effect is become smaller when the modal order is higher. The fundament frequency of the prestressed bridges with 20m and 32m span increases about 5.3% and 6.3% respectively and its fifth modal frequency only increases about 1%. ② The moment of middle-span section of the prestressed bridges decreases about 30% and 25% under the excitation of site ground wave. ③ The contributions of high-order modes can be neglected for the vertical seismic responses of the bridges. ④ The ratio factors of the vertical seismic response in the total response of the middle-span section moment of the prestressed bridges are 24.56% and 26.15% when earthquake fortification intensity 7 level and 38.93% and 41.46% when earthquake fortification intensity 8 level respectively. This means that the influence of the vertical responses should be considered in the seismic design of the prestressed bridges.

Abstract:Based on the force characteristics of structural system, comparative analysis between cable stayed bridge, suspension bridge and other two-tower three-span cable supported bridges is carried out. Compared with tunnel the reasonable selection of structural system within different spans is discussed. Finally the mechanics and economic performances of multi-span cable supported bridge are compared. For two-tower three-span cable supported bridges the analysis indicates that cable stayed bridge should be adopted within 1100m main span preferentially. When span exceeds 1100m, suspension bridge is facing the competition from all the other cable supported bridges and tunnel. Suspension bridge can be adopted when the water depth of anchor, foundation and other factor are appropriate.

Abstract:Subway tunnel is characteristic of large-scale investment, many risk factors, large social impact, etc., which determines the need of risk management during the construction. As the fuzziness of risk, it is difficult to use an accurate probability or a probability interval to describe risks. So this paper suggests that shield excavation risks be analyzed by multiple probability intervals. Based on the five probability intervals which divide risk probabilities into five ranks in the subway and underground engineering, risk factor questionnaire has been designed, and the probability distributions of probability ranks about shield construction risk factors could be figured out through expert survey method. According to the questionnaire, Bayesian Networks is applied to establish a multi-state system to analyze the probability distributions. The multi-state system is used in the risk assessment of a subway tunnel, the probability rank of the project is figured out and at the corresponding probability rank，such risk factors as poor seal in the portals, axis deviation which causes segment failure and the damage, destruction of sealing material are considered as the key control objects.

Abstract:Numerical simulation provides a new way for concrete carbonation research, both for mechanism and engineering application. In order to quantitatively evaluate effect of carbonation process of concrete section corner under stress state, a two-dimensional (2D) numerical model of carbonation process, which takes account of the effects of concrete composition and stress state, is presented in this paper. The process to develop the numerical program is also introduced, the effects of element size and time step are discussed. The numerical program is verified by comparing calculation results with some existing carbonation experiments results, which turned out a good coincide. Finally, an example is used to illustrate the effect of stress state on the carbonation process of concrete section corner. The results show that the carbonation rate in the corner of concrete section is faster than others due to acceleration effects of the two-dimensional diffusion of carbon dioxide into concrete and tension stress state, and attention should be paid to the durability of concrete section corner.

Abstract:The relations between the fatigue life of a asphalt pavement and its average temperature, temperature gradient were discussed, based on the equivalency principal of cumulative fatigue damage, a method for calculating the fatigue equivalent temperature for asphalt pavement was put forward, with reference to the pavement temperature field data collected at 95 areas in China over the years, the corresponding fatigue equivalent temperatures were calculated and analyzed, the correlation between the standard fatigue equivalent temperature and the altitude of asphalt pavement located, the characteristic asphalt pavement temperature (pavement surface average temperature over years and its standard deviation ) were summarized. Hence, the standard fatigue equivalent temperatures for asphalt pavement at 738 areas in China were calculated, for design purpose, a contour map of the standard fatigue equivalent temperatures was initially proposed. Moreover, the influences of various factors in the non-standard conditions on the fatigue equivalent temperature for asphalt pavement were analyzed, and a set of approximate formulas were given accordingly. At last, through comparative study, the reliability of the calculation method and corresponding results were validated.

Abstract:Road base materials plastic deformation, vibration acceleration and pressure power was acquisition by adpoting sensors in vibration molding process, through the output energy analysis of three parameters vibration compaction process, defined vibration compaction process compaction of ability evaluation parameters-vibration intensity E1; Through analysis of the materials vibration compaction plastic deformation curve, defined the compaction assessment index of road base materials- compaction coefficient L; Comparative study was carried out between different road base materials; The result shows that when the vibration intensity is greater than 3.5, the vibration compaction process just have strong compaction ability; There is a logarithmic relationship between vibration compaction plastic deformation and vibration time ,when vibration compaction after 50 seconds later, plastic deformation was in a stable state; In road materials can be compaction, asphalt mixture compacted ability is the worst, the fly ash and lime combining materials compacted ability is the best, the road base materials compacted ability are basicly at the same level. The results of the study show that, it is reasonable to evaluate the compaction ability of vibration compaction process and road materials compacted ability using vibration intensity E1 and compaction coefficient L.

Abstract:Based on a hypothesis superposition theory of nonlinear elastic restoring force (NEF) and nonlinear damping force (NDF), a non-linear dynamic mechanical model was proposed. The rubber absorber was tested according to the working condition and the experimental data was analyzed, found that the simulated result fit the tested result, accordingly verified the validity of this model. The influence law of the amplitude and frequency on the NEF, NDF and the dynamic stiffness was studied. The results show that：With the increase of amplitude, the NEF and the NDF increase rapidly, and the dynamic stiffness increases too. With the increase of frequency, the NEF decreases slightly, but the NDF increases, the dynamic stiffness has an increasing trend too.

Abstract:In order to more effectively assess track quality, a new assessment method of track quality energy index (TQEI) is presented in this paper, which based on Intrinsic Mode Function (IMF) and included the factor of track irregularity wavelength. The data of track irregularity is decomposed into finite IMFs by empirical mode decomposition (EMD). The frequency spectrum and the power of each IMF are calculated by using FFT. The energy coefficient of track irregularity IMF is chosen as the ratio of IMF signal energy to the original signal energy, and then track quality energy index is obtained with the corresponding calculation. Track quality index (TQI) is proved to be a special form of TQEI on certain basis. Finally, the track irregularity signal is studied by the new index, which collected by track recording vehicles from Beijing-Guangzhou Railway. The statistic and analysis result indicates that track quality energy index is the development and deepen of track quality index and to assess the track quality accurately and effectively.

Abstract:A two-stage approach was proposed to solve the problem of connecting suburban rail line to urban rail network based on the current model’s impracticability. Focusing on the first stage, the paper articulates how the set of connection design schemes is generated. A greedy search based heuristic algorithm was designed to solve the optimization problem of connecting suburban lines and urban rail network. And optimum connection scheme set was sorted out from the perspectives respectively regarding optimization searching process and different transfer coefficients that reveal the dominance of transfer in path length. High quality of connection design schemes can be ensured by these optional designs, which can also cover various connection modes of different station spacing, providing solid basis for evaluation and selection in the second stage. Finally, the aforementioned method was implemented in an example, generating an optimized connection design set, which proves the applicability of this novel design method in large scale rail network connection problem.

Abstract:Currently, wireless sync control technology depends mainly on imported and domestic research is not deep enough. In order to study the wireless sync control technology which fit for the domestic locomotive, the article analyzes the characteristics of wireless sync control technology and establishes the mathematical and simulation model of longitudinal force of heavy haul train. From the angle of longitudinal force, verifying the combined train of using wireless sync control technology is superior than traditional train, and calculating the longitudinal force which affected by different delay time between the main control locomotive and the driven control locomotive train to verify the advantages of wireless sync control technology, which provide a reference for further optimizing the wireless sync control system.

Abstract:Batch experiments of dynamic hydrolysis at different hydrolysate replacement frequencies in 96h were conducted to evaluate the effects on anaerobic hydrolysis of organic fraction of municipal solid waste (OFMSW) caused by homogenization pretreatment, overturn, methanogenic effluent and hydrolysate replacement frequency (12 h, 24 h, 48 h, 96 h ). It showed that the operation of overturn mixing improved the hydrolysis efficiency of OFMSW by 42.7% at the most which happened in the methanogenic-buffered scenario without homogenization, and the hydrolysis efficiency in the scenario without the operation of overturn mixing can only be 22.3%. Comparing with the distilled water, using methanogenic effluent as buffer increased the hydrolysis rate of un-homogenized OFMSW by 40.6%. However, the increment was only 3.6% in the hydrolysis of homogenized OFMSW, which indicated that the homogenization had not significantly improved the hydrolysis efficiency, but increased the energy consumption. Hydrolysate replacement to some extent eliminated the inhibition of organic acid. The increments of weight loss by 11.4% and 40.7% were accomplished in the scenarios with hydrolysate replacement frequencies of 24 h·run-1 and 48 h·run-1, comparing with that of 12 h·run-1. However, the energy consumptions increased by 100% and 300%, respectively, suggesting that the hydrolysate replacement frequency of 12 h·run-1 is optimal.

Abstract:Microbial flocculant (MBF) extraction from excess sludge by ultrasonic method was systematically studied. The MBF extracted from excess sludge showed higher flocculating activity under acidic conditions and 35-40 oC. The optimum ultrasonic time and the optimum ultrasonic power were 1-3 min and 210-270 W, respectively. The concentration of the extracted MBF from the sludge by ultrasonic method increased with the rising sludge concentration. To get the best flocculation efficiency, MBF dosage can be decreased with the rising sludge concentration. The main components of MBF consisted of proteins, polysaccharides, and nucleic acids. According to the results, ultrasonic method was feasible to extract MBF from excess sludge, which could not only save the cost of MBF production, but also realize the resource reuse of excess sludge.

Abstract:A batch test was made to evaluate the adsorption properties of Copper on humus soil. Several factors have been studied with regarding their effects on adsorption characteristics, such as adsorption time, initial concentration, humus dosage, initial pH and temperature. Furthermore the relevant mechanisms have been studied with assistance of adsorption kinetics, adsorption isotherm and FTIR. The results show that the amount of Cu2+ adsorbed on humus soil increases with adsorption time until it reaches equilibrium, and increases with the increase of initial Cu2+concentration and initial solution pH value, while decreases with the increase of humus dosage, and temperature almost does not affect the adsorption. The adsorption process follows the pseudo-second-order model and Freundlich adsorption isotherm equations, and the adsorption process mainly bases on chemical adsorption. The analysis of FTIR indicates that the main groups involved in adsorption are hydroxyl and aromatic.

Abstract:In many Chinese residential communities, reclaimed water reuse system meet the problem of long-term application for the poor water quality and sensory discomfort. Aimed to meet the “Standard of Urban Wastewater Reuse” for miscellaneous water consumption (GB/T 18920-2002) and scenic environment use (GB/T 18921-2002), a pilot-scale Anoxic/Oxic Membrane Bioreactor (AO-MBR) followed by activated carbon filter and ultraviolet combined chlorine disinfection devices were installed to treat the mixed domestic wastewater in a residential area in north China. The objectives of the research were to investigate the reclaimed water qualities and optimize the main operating parameters; furthermore, to analyze the technical and economic suitability for treatment of the mixed domestic wastewater with grey water only. The results showed that, when the mixed domestic wastewater (effluent of septic tank) was chosen for treatment, under the conditions of Hydraulic Retention Time (HRT) 8h, mixed liquor suspended solids (ρMLSS) 3500~7500 mg•L-1, the effluent was colorless and odorless, the chemical oxygen demand (ρCOD), Biochemical Oxygen Demand(ρBOD5) and ammonia nitrogen(ρNH3-N) was respectively below 30 mg•L-1, 3 mg•L-1 and 3.0 mg•L-1, which can stably meet the “GB/T 18920-2002”, however, the total nitrogen(ρTN) and total phosphorus(ρTP) concentration of effluent can’t meet the requirements of “GB/T 18921-2002”; While simulating the ρCOD: ρTN: ρTP ratio of the raw wastewater (influent of septic tank), under the conditions of HRT 10 h, SRT 50 d, the recycling ratio 200%, ρMLSS 5500~6000 mg•L-1, the dosage of poly-aluminum chloride(ρPAC) 4~5 mg•L-1, the effluent quality was better than the “GB/T 18920-2002” and the “GB/T 18921-2002”. To achieve the same reclaimed water quality, the mixed domestic wastewater treating process is more complicated than that of the grey water, at the same time, the operating cost is 0.32 Yuan•m-3 higher than the later. Therefore, from the views economic and technical feasibilities, it should be taken into account the demand and potential usage of the reclaimed water, the local climate conditions during selecting a suitable wastewater collecting and treating system in residential areas.

Abstract:To recover groundwater contaminant source’s release history according to the obtained monitoring data belongs to groundwater inverse problem. In this study, a hybrid simplex-simulated annealing method is adopted and incorporated with the analytical solutions of the contaminant transport equation to recover the history of groundwater contaminant. The hybrid SMSA algorithm incorporates the deterministic search pattern of simplex method and the global probabilistic search mechanism of simulated annealing algorithm, and has proved to be a robust hybrid optimization algorithm. Meanwhile, the analytical solution to contaminant transport equation proposed by Yeh is adopted and realized in this study, for the characteristics of this analytical solution are reliability, easy programming and scalability. As shown by the calculation results, the recovered release history obtained by hybrid SMSA method and Yeh’s analytical solution is well reproduce the real process of contaminant release. It is further concluded that hybrid SMSA method and its incorporation with Yeh’s analytical solutions can be widely used in reconstructing the release history of groundwater contaminant.

Abstract:With the feature of multi-production line, multi-order and multi-product, small lot in multi-item order enterprise, an order scheduling model was established. The objective of the model is to minimize the overall completion time of all orders and average flow time. A new integrated thought of multi-rule order assignment and job sequencing was proposed. And based on an improved non-dominated sorting genetic algorithm for this model. By searching the contour matrix, the algorithm speed was improved .Then, double recoding was used to reduce time and space complexity. A adopted hybrid mutation improves the algorithm’ premature properties Comparison of examples verified that the solution may acquire valid Pareto results.

Abstract:In this paper, a mathematic model for a 45kW proton exchange membrane fuel cell (PEMFC) engine system has been proposed. The model includes a fuel cell stack, reacting gases supply subsystem as well as water/thermal management subsystem. As for calculating the stack voltage, an error correction term is introduced in order to improve model accuracy. Subsequently, the model has been validated experimentally. The coolant temperature at stack inlet, air excess ratio and air pressure at cathode inlet have been chosen as the manipulating variables, meanwhile the corresponding sensitive analysis and systematic response have been made under the giving current densities. The simulation results show that, in order to obtain the higher performances of the PEMFC engine system, the coolant temperature at stack inlet should be reduced appropriately, while the air pressure at cathode inlet should be regulated as high as possible, in order to maintain rational stack temperature, the water/thermal management subsystem should be controlled effectively.

Abstract:Graph embedding discriminant analysis on manifold approach represents each image set as a subspace on manifold. It maps the manifold to a more discriminative one with geometrical structure and local information preserved. However, its accuracy critically depends on the number of local neighbours when constructing similarity graph. In this paper, we present a novel approach with fixed neighbour numbers to implement graph embedding Grassmannian discriminant analysis based on low-rank representation (LRR) for each image set. After recovering the low-rank components of each set, we find that preserving the nearest neighbour structure of nodes with same label and all the different label information during the manifold mapping can always achieve the best performance. Experiments on two image datasets (15-scenes categories and Caltech101) show that the proposed method greatly improves the classification accuracy of image sets.

Abstract:An extra matters recognition method was proposed to sift images with extra matters from amounts of power system images, aiming at improving the detection efficiency on the fault point in transmission line patrol for the potential extra matters danger in the transmission corridor．Firstly, the Otsu self-adaptation threshold segmentation algorithm was improved to segment the aerial images based on the mathematical morphology algorithm. Then a new filter algorithm to extract target image based on the geometrical characteristic of straight line was proposed to filter the rest of background. In addition, the transmission line edges were calculated via gradient. Then the local maxima in Hough transfer accumulator and the final line number were chosen as feature vectors to recognize extra matters. Finally, an interface was developed to verify the algorithm. The result shows that this method can sift all the images with extra matters, providing reliability for the power system.

Abstract:Singular spectrum analysis (SSA) was introduced to data processing of station coordinates, including treatment of missing values, identification and extraction of trends and cycles. Singular spectrum analysis，a statistical technique with reconstruction and empirical orthogonal function, can effectively extract trends and cycles from the limited scale of the time series with noise. Hence, SSA has been applied to various time series analysis. It took advantages of the singular spectrum analysis and applied SSA to the process of GPS time series. Coordinate time series from Crustal Movement Observation Network of China GPS data services was used by SSA for treatment of missing values (MSE of interpolation at every direction are in millimeter degree), reconstruction and extraction of trend (N:-11.688mm/a,E:29.585mm/a,U:2.557mm/a) and cycle components (N:0.5a、1a, E:1a, U:0.25a、0.5a、1a、1.5a). The results showed that obvious trend, significant cycles and noise do exist in each direction of BJFS.

Abstract:In this paper, the convergence of the Broyden algorithms without convexity and exact line search assumptions is discussed. It is proved that if the objective function is suitably smooth and the DFP algorithm produces a convergence point sequence, then the limit point of the sequence is a critical point of the objective function. We give mainly a proof for the DFP update, then point out that all the results are true for Broyden algorithms by a remark.

Abstract:SThe topic of the present paper is the spatiality of (α, β)-derivations of operator algebras. Suppose that X is a Banach space, A is a subalgebra of B(X) and α, β are automorphisms on B(X). It is shown that any reflexive transitive (α, β)-derivation is quasi-spatial. If the norm closure of A contains a nonzero minimal left ideal, then a bounded reflexive transitive (α, β)-derivation δ from A into B(X) is spatial and the implementation T of δ is unique only up to an additive constant.

Abstract:Two equivalent formulations for the effective density and the effective bulk modulus of fibrous materials were derived from the microscopic scattering process of the filaments according statistical consideration by Zhao Songling. Then there are some difference between its theoretical results and experimental data. This difference will increase with sound frequency increases. Its cause maybe lay in the glue effect. Considering glue effect and introducing definition of equivalent volume mass, the improvement equivalent formulations were proposed, and an experimental examination is discussed also. Theoretical results are in better agreement with the experimental data. The effects of glue, volume mass, fibrous radius and thickness on acoustic properties were discussed using the improvement equivalent formulations. The analytic results are perfectly agreement with the conclusion from a large number of measurement data on acoustic properties of fibrous absorbing materials.

Abstract:A real construction project contains lots of uncertain factors. Based on the fuzzy description of the interrelation among the three goal functions of time, cost and quality, a fuzzy trade-off model is established by using activity duration time as decisive variable. In addition, the immune genetic particle swarm optimization (IGPSO) is proposed to solve the model in the base of particle swarm optimization. In order to test the effectiveness of IGPSO, we use the Matlab simulation to test different benchmark functions and apply it to solve the fuzzy trade-off problem of real construction projects. As a result, the different fuzzy Pareto optimum solutions and their relevant three-dimensional scatter diagram illustrate the model’s feasibility and the effectiveness of IGPSO ,which can be used by decision makers to make a reasonable decision.

Abstract:Project Delivery System (PDS) is one of the crucial success factors for construction project. From the perspective of Project Production efficiency, this paper constructed a project production efficiency index system and built the corresponding project production frontier of PDSs for comparing Design-Bid-Build(DBB) and Design-Build(DB) delivery system by applying Production Frontier and Data Envelopment Analysis method. Basing on the comparison of DBB and DB’s efficiency, this paper draw a conclusion that DBB delivery method has advantage in duration, while DB has advantage in cost. On such results, the inner mechanism was further explored, thus to provide a scientific decision- making support for owner’s PDS selection practice.

Abstract:Driving force direction control strategy based on velocity signal for a linear engine/generator system was proposed and starting performance of this system was studied with Matlab/Simulink software. Results show that driving force direction needs be precisely controlled for starting successfully. With the control strategy based on velocity signal, system power loss is little and the driving force is optimized at 135N. Furthermore, the working frequency and distance of the moving part increases gradually for a few starting cycles until it reaches the steady state condition.