Search

Female receptivity in mating is crucial for successful copulation, but protocols for quantifying female behaviors reflecting receptivity are scarce compared to the analysis of male behaviors. Here, we present a protocol for assessing the sexual receptivity of female Drosophilathat considers behaviors from both sexes. We describe steps for preparing and loading flies into a courtship chamber, video recording the behaviors of the pairs, and analyzing their behavioral displays. This protocol includes behavior recognition criteria suitable for typical laboratory settings.

This article calculates the thermal fields and thermal stress fields of the subway tunnel concrete during construction using finite element software ABAQUS. With the calculating laws of distribution of the two fields mentioned above, this paper provides several suggestions for designing and constructing of subway tunnel.

n order to research torsional performance of prestressed steel-concrete composite box beam with different shear connection, this paper designed three prestressed steel-concrete composite box beams with different degree of shear connection, and studied the stress characteristics of prestressed composite beam under static torsion process load. The torsion behaviors of prestressed composite beam such as the steel strain, concrete flange strain, rebar strain, angle of torsion, deformation and failure patterns are analyzed on the base of the experimental results. It comes to a result that shear connectors have little impact on beams cracking torque, but ultimate torque of composite beams decreases along with the reduction of shear connection degree. When the shear connection degree is 0.5, the ultimate torque is reduced by about 15%.

Based on specimen size, which is the main reason of the shear fracture toughness of concrete, experimental research was carried out by 5 groups including 40 symmetrically loading specimens with different length and height. Through load and crack tip sliding displacement curve P-CTSD, load and strain curve P-ε and load and time curve P-t, the effects of length and height of specimens to shear fracture toughness were studied. Specimen stability is strengthened with increasing of length and weakened with increasing of height. Size effect of fracture toughness is weakened with increasing of length, is strengthened with the increasing of height. Fracture toughness increases with the increasing of length, decreases with the increasing of height. Research Background The size effect exists in parameters of concrete, such as concrete strength, modulus of elasticity, fracture toughness, fracture energy and so on [1-. In 1961, the theory of fracture mechanics was applied to concrete structure for the first time by Kaplan [. A vast majority of research work about concrete fracture mechanics was carried out by international scholars [6-. As the development of fracture theory of concrete, the size effect of fracture parameters became the focal point in theory study. Karihaloo [ pointed out that the size effect of concrete strength strengthens with the increasing of components size, however, the size effect weakens when crack length decreased relative to the size of specimens. Hu [3, 10, 11] accounted for the size effect by applying the theory of boundary effect and carried out the concept of local fracture energy which changes with width of fracture process zone. Based on the fictitious crack model, an analytical method [12, 13] for predicting the effective fracture toughness of concrete of three-point bending notched beams is proposed and the effects of initial seam height ratio and height on fracture parameters were carried out by Wu and Xu. At present, research on shear fracture toughness of concrete is immature and there are almost no papers about the size effect of shear fracture toughness of concrete. Aiming at the issue, this paper conducts a study on the size effect of shear fracture toughness of concrete by using symmetrically single-edge notched specimen.

Based on double-K fracture model, adopt three-point bending beam which has been recommended by RILEM, the fracture properties of three groups reinforced concrete beams were studied. Refer to the relevant literature, fracture parameters of reinforced concrete three-point bending beams are examined. Through the analysis of whole process of crack propagation of reinforced concrete three-point bending beams, the results show that the reinforcement ratios can't preventing the cracking effectively, but can increase the maximum loads, thus improving the relative toughness; the precritical crack propagation length relative values show a linearly increasing trend with the increase of reinforcement ratios; the initial fracture toughness is not affected by the reinforcement ratios, but the unstable toughness has little effects by the reinforcement ratios.

This paper focus on the model updating of civil structural systems. Traditional modal test method can identify the frequency of the civil structure accurate, but it is difficult to identify the mass-normalized mode shape. By adding a series of known masses to the structure, measuring the frequency of this mass-modified system, and only using this set of frequency data, the mass-normalized mode shape of the structure can be identified. And the model updating method was developed, which constructed an objective function through the frequency of the measurement and the FE model, corrected the FE model's parameters to minimize the objective function. The example was included to show the capabilities of the technique. The finite element model of the fixed-free beam was updated by the dynamic characteristics which was identified from the modal test, the results show that updated results coincided with the experience of the analyst.

In order to study the influence of the crack-depth ratio on reinforced concrete fracture parameters and the resistance of the reinforcing bar to crack propagation in concrete, the fracture tests were carried on by using four groups three-point bending specimens with initial crack-depth ratios of 0.2, 0.3, 0.4 and 0.5 in this paper. An analytical model was presented to calculate fracture toughness of reinforced concrete by analyzing crack propagation process of the three-point bending beams. The formula of calculating effective crack length of reinforced concrete was established. The research results show that the double-K criterion can be used for describing crack propagation process of reinforced concrete by introducing fracture toughness, which is suitable for reinforced concrete. Initiation fracture toughness and unstable fracture toughness of reinforced concrete slowly increase with the increase of crack-depth ratio, which is different from the properties of ordinary concrete. The reinforced can improve the ductility of concrete obviously and inhibit the rate of crack propagation well.

The mechanical performance of concrete structures closely relates to the propagation of cracks. Depth studying energy dissipation of concrete in fracture process zone not only contributes to comprehensive understanding fracture failure mechanism of concrete, but also has significant in detecting and forecasting the cracks in actual structure. In view of this, a general equation for calculating at any time’s mean energy dissipation per unit length was given. After that, we further simplified and deduced the general equation and got a simple, practical and high accuracy numerical solution, with which Gauss integration method was used. At last, the specific steps of calculating mean energy dissipation were given by taking 10 three-point bending beams of different crack-depth ratios for an example. Compared with test dates, we found that calculated results are in good agreement with the test dates. According to results, influence of crack-depth ratio on the fracture energy was also discussed.

A large number of Concrete Structures need be reinforced in china. So as new rehabilitation and reinforcing techniques, the SRAP approaches were introduced in this paper, and the SR strengthens materials and AP modified resin mortars were combined with pre-stressed method in SRAP approaches. First, nowadays structure distress characteristics were presented and lots of reinforcing techniques were compared and analyzed in this paper. Based on the SRAP advantages such as the concrete crack rehabilitation and its used material innocuity and so on, the analysis results show that the SRAP are feasible and reasonable to guide the design and operation of structure rehabilitation and reinforcement, The SRAP construction measures and expected reinforcing effects were given out in this paper. The results shows that SRAP approaches with numerical simulation is feasible to guide structure rehabilitation and reinforcement，and the proposed SRAP engineering measures are effective for preventing structure local fracturing and satisfaction of rehabilitation and reinforcement targets.

Rotating discs are used widely as important structural elements in mechanical engineering. In order to obtain an optimal structural design, it is necessary to estimate the angular velocity and the stress distribution of a rotating disc in fully plastic state. So J2 deformation Theory is used for large deformation analysis of axisymmetric rotating disk. The bursting speed of rotating disk, the stress distribution at instability and analysis on the elastic-plastic interface of rotating disk are studies in detail.

Based on the experiments, the parameters of acoustic emission signals were discussed about cracks, expansion and instability of concrete in this paper. The relationship between different acoustic emission signals of concrete were established on damage constitutive relation. A new method was provided by damage assessment for hydraulic structures.

In order to research that how the degree of shear connection influence the static properties of composite beams such as the relative slip on the interface、bearing capacity and failure mode, four prestressed composite beams with different the degree of shear connection were designed, and were loaded on the two symmetric position. The paper described and analyzed the bending behaviors of prestressed composite beam such as the strain distribution of sections、interface slip、deformation and failure patterns on the base of the experimental results. In addition, the paper revised the calculating formulas of the ultimate bending capacity of composite beams with partial shear connection in Eurocode 4 with the least square method combined with test results of domestic and overseas about seven composite beams. The results showed that the correction values were corresponding well with experimental data and the engineering accuracy.

In combination with a certain road tunnel instance Ningwu Highway，a working face rock ahead of forecast model is established. The prediction criterions include the Working face of rock radar images coefficient factor rock tunnel face conditions and the tunnel observation and analysis of geological factors are determined in the article. Their evaluation indexes are determined by the principle of which degree comes close and judged by experts. Finally the prediction results are came up through the fuzzy comprehensive evaluation and compared with the indexes of the degree of stability. Then it can make the prediction conclusion. The result shows that the model is convenient to use in practice very well. So it is proved that this prediction model is reliable.

As a modern nondestructive testing technology,acoustic emission which is the important research of fracture mechanics analysis method and the effective ways of evaluation, can convenient to discrimination of concrete structures, properties and internal defects of concrete material. Firstly this article expounded the research progress of the acoustic emission at home and abroad in the field of concrete, especially in the field of research progress of concrete dam.Through the improvement of testing equipment and testing system, concrete fracture parameters had been introduced into the acoustic emission experiments. Not only can they control the loading rate in the test accurately, but also can monitor the real-time of crack state.The specimens can be accurately judged for the specimen cracking and instability and failure of the moment and characteristics.According to the concrete fracture critical state of acoustic emission characteristics identification, fracture criterion of acoustic emission of concrete had been established.Experimental results showed that the acoustic emission characteristic parameters can be accurate judged on time and in good agreement with traditional strain measurements. This criterion is more intuitive and easier for operation. Thus acoustic emission provides a theoretical and technical support in the concrete application of the fracture parameters test.

This paper first elaborates the domestic and foreign study and applying current situation in terms of the concrete testing field regarding to acoustic emission technology, especially the study progress in the large dam concrete field. By improving the current test device and updating and reforming the measuring equipment, the task team introduces the acoustic emission testing system into the concrete double-K fracture parameter test. The new device can not only accurately control the loading velocity in the test, but also correctly judge the time and property of cracking, instability and damage of specimen. This paper establishes the acoustic emission criterion for concrete fracture according to the recognition features of acoustic emission of concrete in fracture critical state. The test result presents that the cracking time of specimen can be correctly judged by using feature parameters of acoustic emission, which properly matches the cracking time measured by the traditional strain method, and this judging is more direct and convenient for on-site operation, providing theoretical and technical support for application in the concrete fracture parameter test by acoustic emission technology.

Rotating discs are used widely as important structural elements in mechanical engineering. In order to obtain an optimal structural design, it is necessary to estimate the angular velocity and the stress distribution of a rotating disc in fully plastic state. So Large deformation and discontinuous yield analysis of rotating disks were analyzed by ABAQUS. Moreover, continuous yield, buckling and bifurcation analysis of rotating disk with discontinuous yield were studied. Then, Minidisk model is analyzed using ABAQUS.