桥梁隧道施工常见问题及控制对策探析

近年来,随着桥梁隧道事业的发展,我国交通网络日趋完善。在桥梁隧道工程建设中,桥梁隧道施工相对于其他工程来说更加危险,因此在施工中要考虑到工程的整体施工质量和效率,还要考虑到人员的安全。施工必须结合地形条件,做好防水和防腐处理,确保桥梁隧道工程运行的稳定性和安全性。然而许多工程建设由于技术应用不当、管理问题和材料使用问题,会导致各种问题的发生。基于此,本文分析了桥梁隧道施工中的普遍问题,提出了加强桥梁隧道施工技术和管理控制的相关建议。

Forced convection rheoforming process for preparation of 7075 aluminum alloy semisolid slurry and its numerical simulation

A self-developed forced convection rheoforming （FCR） machine for the preparation of light alloy semisolid slurry was introduced. The microstructure characteristics of 7075 aluminium alloy semisolid slurry at different stirring speeds prepared by the FCR process were analyzed. The experimental results suggest that with the increase of the stirring speed, the mean grain size of the semisolid decreases and the shape factor as well as the number of primary grains increase. Meanwhile, the preparation process of semisolid slurry was numerically simulated. The flow characteristics of the melt in the device and the effect of the stirring speed on temperature field and solid fraction of the melt were investigated. The simulated results show that during the preparation process of semisolid slurry, there is a complex convection within the FCR device that obviously changes the temperature field distribution and solid fraction of the melt. When the convection intensity increases, the scope of the undercooling gradient of the melt is reduced and temperature distribution is improved.

Studies on Benign Working Pairs for Adsorption Refrigeration

Water and ethanol were selected as refrigerants, 13x molecular sieve, silica gel, activated carbon and adsorbents NA and NB prepared by authors were selected as adsorbents, and the performance of adsorption working pairs in adsorption refrigeration system was studied. The adsorption isotherms of adsorbents (NA and NB) were obtained by high vacuum gravimetric method. Desorption properties of adsorbents were analyzed and compared by thermal analysis method. The performance parameters of adsorption refrigerat...

J2EE-BASED DISTRIBUTED AND INTEGRATABLE MANUFACTURING EXECUTION SYSTEM

Using the Java 2 enterprise edition (J2EE), the industry standard technique, a component and web-based manufacturing execution system (MES), is presented. It is considered to be open, modularized, distributed, configurable, interoperable and maintainable. After introducing some core techniques of J2EE as the basic foundations of the proposed MES, this paper briefly analyzes the MES domain in manufacturing systems and constructs the abstract object and component model, and then establishes the MES architecture. This MES can be facilely integrated with other manufacturing applications. Finally, an example of integration with the enterprise resource planning (ERP) system is given.

Supply chain coordination mechanisms under asymmetric information with retailer cost disruptions

A two-level supply chain model involving one supplier and one retailer with linear demand is developed, and supply chain coordination mechanisms under asymmetric information （the retailer＇ s cost structure is asymmetric information） are proposed by employing game theory in two scenarios： coordination mechanisms under asymmetric information in a regular scenario （without disruption）; and coordination mechanisms under asymmetric information in an irregular scenario （ with retailer cost disruptions）. It is optimal for the supply chain to maintain the original production plan and to guarantee a steadily running system if variations of retailer costs are sufficiently low and do not exceed an upper bound. This shows that the original production plan has certain robustness under disruptions. Decisions must be re-made if a retailer＇ s cost change is greater and exceeds an upper bound. Impacts of retailer cost disruptions on the order quantity, the retail price, the wholesale price and each party＇ s as well as the system＇ s expected profits are investigated through numerical analyses.

Combination Computing of Support Vector Machine, Support Vector Regression and Molecular Docking for Potential Cytochrome P450 1A2 Inhibitors

The computational approaches of support vector machine （SVM）, support vector regression （SVR） and molecular docking were widely utilized for the computation of active compounds. In this work, to improve the accuracy and reliability of prediction, the strategy of combining the above three computational approaches was applied to predict potential cytochrome P450 1A2 （CYP1A2） inhibitors. The accuracy of the optimal SVM qualitative model was 99.432%, 97.727%, and 91.667% for training set, internal test set and external test set, respectively, showing this model had high discrimination ability. The R2 and mean square error for the optimal SVR quantitative model were 0.763, 0.013 for training set, and 0.753, 0.056 for test set respectively, indicating that this SVR model has high predictive ability for the biolog-ical activities of compounds. According to the results of the SVM and SVR models, some types of descriptors were identi ed to be essential to bioactivity prediction of compounds, including the connectivity indices, constitutional descriptors and functional group counts. Moreover, molecular docking studies were used to reveal the binding poses and binding a n-ity of potential inhibitors interacting with CYP1A2. Wherein, the amino acids of THR124 and ASP320 could form key hydrogen bond interactions with active compounds. And the amino acids of ALA317 and GLY316 could form strong hydrophobic bond interactions with active compounds. The models obtained above were applied to discover potential CYP1A2 inhibitors from natural products, which could predict the CYPs-mediated drug-drug inter-actions and provide useful guidance and reference for rational drug combination therapy. A set of 20 potential CYP1A2 inhibitors were obtained. Part of the results was consistent with references, which further indicates the accuracy of these models and the reliability of this combinatorial computation strategy.

Study of Object Oriented Petri Net and Its Application in Flexible Manufacturing Cells

This paper presents an object oriented Petri net (OOPN) schema to model the dynamic behaviors of a flexible manufacturing cells (FMCs). The OOPN paradigm incorporates the characteristics of a Petri net and OOP. It increases the maintainability and reusability of objects in Petri net modeling, thus it has more powerful modeling and analysis abilities.

Effects of Salinity and Dietary Chinese Herbal Medicine on Survival and Growth of Juvenile Fenneropenaeus chinensis

[Objective] The aim of this study was to provide theoretical basis for the large-scale breeding of Fenneropenaeus chinensis as well as the promotion of Chinese herbal medicine.[Method] The experiment was conducted to determine the effects of salinity（12‰,20‰ and 28‰）and dietary Chinese herbal medicine（CHM：0%,1%,2% and 4%）on survival and growth of juvenile F.chinensis with the average initial wet body weight of 0.027±0.005 g.The experiment lasted for 5 weeks.[Result] The survival rate,specific growth rate,food consumption and apparent digestibility coefficient was increased with CHM level increasing;when attained the critical value,the survival rate,specific growth rate,food consumption and apparent digestibility coefficient decreased with CHM level increasing.Food conversion ratio decreased with CHM level increasing,and then it increased after attained the critical value.At each CHM level,the survival rate,specific growth rate,food consumption and apparent digestibility coefficient were highest at salinity of 20‰,while food conversion ratio was lowest at salinity 20‰.[Conclusion] Salinity and CHM had a significant effect on growth of F.chinensis,which should be paid more attention in the breeding.

浅谈存货审计中应注意的问题及对策

企业存货审计的主要目标是确定存货的真实性,合法性、正确性以及存货增减的变化是否正确。企业的库存存货是反映企业生产经营、流动资金运作情况的重要指标,通过存货的控制可以达到调节利润,偷逃国家税款的目的,所以存货审计历来是审计的重点,本文结合审计实际就库存审计应注意的问题谈些粗浅的认识。

OPTIMAL CONTRACTS IN TWO-ECHELON SUPPLY CHAIN UNDER ASYMMETRIC INFORMATION AND NONLINEAR DEMAND

The challenge for supply chain management is to create appropriate supply chain contracts so as to optimize the system performance. To examine the role of asymmetric information in a two-echelon supply chain system and derive supply chain contracts to deal with existing asymmetric information, a two level supply chain model including one Supplier and one retailer under the demand of price elasticity is developed. By using the principalagent principle and the optimal control theory, three types of supply chain contract, i. e. , a wholesale pricing contract, a two-parameter linear and a two-parameter nonlinear contracts are obtained. In these contracts, the Supplier has asymmetric information about the retailer cost structure. Simulation results show that the two-parameter contracts are more effective strategies to achieve supply chain coordination.

Present Situation and Promoting Strategies of Maca Industry in Yunnan

Maca is an important health-care product. Recently, maca industry devel- ops fast in Yunnan Province, but still falls behind of foreign industries, due to dis- advantages of being late starter and poor economy. In the research, maca industry development was analyzed in terms of production bases, processing enterprises, dis- tribution in dominant areas, planting and processing technology system, and eco- nomic benefits, and the restriction factors were explored. Finally, some measures were proposed, including reinforcement of organization and leading roles in a macroscopic way, giving supports to financial investment, broadening financing chan- nels, speeding up construction of raw material production bases, improving modern science and technology development, establishing technology support system, culti- vating leading enterprises, building marketing system, and supervision on product eualitv.

Phylogenetic Analysis of Cystatin

[Objective] The molecular weight,isoelectric point,signal peptide,domain and other properties of the encoding protein of the known cystatin genes were analyzed.[Method] Cystatin genes were searched in NCBI and the related amino acids sequences were downloaded.SMART software was used to predict the domain.SingalP program was used to search signal peptide.TMHMM program was used to search and predict the transmembrane domain.CLUSTAL W program was used to make multiple sequence alignment.Using MEGA3.1 software,...

Controlled Secure Quantum Dialogue Using a Pure Entangled GHZ States

We present a controlled secure quantum dialogue protocol using a non-maximally （pure） entangled Greenberger-Horne-Zeibinger （GHZ） states at first, and then discuss the requirements for a real quantum dialogue. We show that the authorized two users can exchange their secret messages after purifying the non-maximally entangled GHZ states quantum channel unconditionally securely and simultaneously under the control of a third party.

Amplitude modulation measurement of symmetrical microwave power sensor

In order to reduce the mismatch error, a direct current （DC） calibration method is introduced when the modulated microwave signal is measured. The microwave power is input to the left section of the power sensor, and the DC power is input to the right of the power sensor. Due to the existence of parasitic loss and electromagnetic coupling, the microwave power results in a mismatch error. However, the DC power does not have the mismatch error. So the DC power applied in the right section can calibrate the mismatch error of the microwave power in the left section. The calibration factor is measured at different modulation rates and modulation depths.The measurement results show that the carrier frequency is the major factor influencing the measurement results. After calibration, the carrier frequency and the modulation rate have little effect on the output voltage. The frequency response becomes relatively flat in the frequency range up to 20 GHz, and the sensitivity on average is enhanced by about 0.12 mV/dBm. Therefore, the DC calibration method has a certain reference value for the terminal-type microwave power sensor.

Experimental Study of Fouling on Heat Transfer Surface During Forced Convective Heat Transfer

An experimental study was conducted to investigate the fouling process of calcium carbonate on the heat transfer surface, during forced convective heat transfer. The dynamic monitoring apparatus of fouling resistance was set up for the present experiments. The fouling behavio（s were examined under different factors including fluid velocity, hardness,alkalinity, solution temperature, and wall temperature. Asymptotic fouling curves varying with time were obtained. The fouling rate and asymptotic fouling resistance increased and the induction periods were shortened with the fluid velocity decreasing, hardness andalkalinity increasing, and solution temperature and heat transfer surface temperature increasing. Thecomponents of fouling that formed on the heat transfer surface included crystallization fouling and particulate fouling. The thermal performance parameter of fouling,ρfhf, varied from 380 to 2600 kg·W·（m^4·K）^-1, increasing with growing velocity and decreasing solution temperature, hardness or alkalinity. Furthermore, the thermal conductivity of fouling, λf, varied from 1.7 to 2.2 W·（m·K）^-1 .

Dynamic performance of six-axle locomotive subjected to asymmetric brake shoe forces

To research the influence of asymmetric brake shoe forces(ABSF)induced by braking failure on the dynamic performance of six-axle locomotive,the static equilibrium model of three-axle bogie and dynamic model for locomotive are established.The coupling vibration equations of axle hung motor and wheelset are derived.For the air braking,the influence mechanism of ABSF on the wheel-rail asymmetric motion and force characteristics are discussed.It can be found that if the ABSF is applied in the front wheelset,all the wheelsets move laterally in the same direction.Once the ABSF occurs in the middle or rear one,other wheelsets may move laterally towards the opposite direction.The motion amplitude and direction of all wheelsets strictly depend on the resultant moment of suspension yawing moment and brake shoe asymmetric moment.For the asymmetric braking,the free lateral gap of axle-box could increase the wheelset motion amplitude,but could not change the moving direction.In both the straight line and curve,the ABSF may lead to wheelset misaligning motion,intensify the wheel-rail lateral dynamic interaction and deteriorate wheel-rail contact state.Especially for the steering wheelsets,the asymmetric braking increases the wheelset attack angle significantly,which forms the worst braking condition.

Application of Box-Behnken Design in Optimization of Allelopathic Effects of Potamogeton Pectinatus Against Microcystis Aeruginosa

Allelopathic effects of submerged macrophytes against algae are affected by many environmental factors which can only be measured one by one by traditional methods. Box-Behnken design of response surface methodology was used to optimize three environmental factors （temperature, light intensity and total dissolved solids） of allelopathic effects of Potarnogeton pectinatus against Microcystis aeruginosa at the same time. By solving the regression equation and analyzing the response surface contour plots, the optimal conditions of the relatively inhibitory rate of Microcystis aeruginosa were that the temperature was 23℃, the light intensity was 2 700 lx and the total dissolved solids were 4 415 mg/L. Under these conditions, the optimal value of relatively inhibitory rate of Microcystis aeruginosa was 81.9%. According to validation experiments, the results of analysis indicated that the experimental values fitted well with the predicted ones.

A Priori and A Posteriori Error Estimates of Streamline Diffusion Finite Element Method for Optimal Control Problem Governed by Convection Dominated Diffusion Equation

In this paper,we investigate a streamline diffusion finite element approxi- mation scheme for the constrained optimal control problem governed by linear con- vection dominated diffusion equations.We prove the existence and uniqueness of the discretized scheme.Then a priori and a posteriori error estimates are derived for the state,the co-state and the control.Three numerical examples are presented to illustrate our theoretical results.

Effect of flow rate on environmental variables and phytoplankton dynamics:results from field enclosures

To investigate the effects of flow rate on phytoplankton dynamics and related environment variables,a set of enclosure experiments with different fl ow rates were conducted in an artificial lake. We monitored nutrients,temperature,dissolved oxygen,p H,conductivity,turbidity,chlorophyll-a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s,which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light,resulting in a dramatic shift in phytoplankton composition,from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However,flow rate significantly enhanced the inter-relationships among environmental variables,in particular by inducing higher water turbidity and vegetative reproduction of periphyton( Spirogyra). These changes were accompanied by a decrease in underwater light intensity,which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist,because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.

Effect of asymmetric rolling under high friction coefficient on recrystallization texture and plastic anisotropy of AA1050 alloy

In asymmetric rolling(ASR) the circumferential velocities of the working rolls are different. This yields a complex deformation mode with shear, compression and rigid body rotation components. The main microstructural modification is on crystallographic texture, and, for aluminium alloys, this may improve the deformability after recrystallization. This work correlated the process variables, thickness reduction per pass(TRP) and velocity ratio between the upper and bottom rolls, with the texture development and the plastic properties after annealing. Finite element(FE) simulations were performed to quantify the influence of the strain components. Experimental data on texture, and plastic anisotropy were analyzed. In the sheet centre a crystallographic rotation of the compression components about the TD(transverse direction) axis was obtained, which yielded the development of {111}//ND(normal direction) texture components. On the surfaces the local variation of the velocity gradients caused an extra rotation component about ND. This yielded the increment of rotated cube components. After annealing the main texture components at the sheet centre were maintained and the texture intensity decreased. The planar anisotropy(△r) was reduced but the normal anisotropy and deep drawability obtained by the Erichsen test were similar for all conditions. The most favourable reduction of △r was obtained at a velocity ratio of 1.5 and TRP of 10%.