Applied Mechanics and Materials Vols. 249-250

Abstract: Amending the normal stress over the slip surface based on the stress field by numerical analysis, applying the three-dimensional global limit equilibrium method to the stability analysis of tension-slackened rock mass in the right bank of Yagen hydropower station. Stability analysis shows that if do not take any measures, the loose rock mass stability can cater to the Specification demand, but some small sliders is in the limit state under the water and earthquake condition, if use the cutting slope and unloading scheme, the whole loose rock mass and the all small sliders can meet the Specification standard stability requirements.

Abstract: The paper is focused on the problems of the mechanical properties of steel used for load-carrying structures of civil engineering constructions, especially from the viewpoint of properties of old steels used in historical constructions in comparison with current steels. Chemical composition and physical-mechanical properties of historical steels can be important, for example, in the case of reconstructions, when for the static assessment and evaluation of existing constructions subjected to new (higher) loading actions, material properties of load-carrying structure must be known. In the case of constructions aged about 100 years, usually no project documentation and no information about used material and its properties exist. Then, the properties must be determined using material tests carried-out on the test specimens taken from the real existing structure. But here the sampling of test specimens is limited by the possibilities of existing structural system and by the dimension of particular members from which the specimens are taken, so that the test specimen dimensions and number are limited. Thus, the evaluation of material properties for obtaining representative design values can be more difficult and less reliable than in the case of the large test number. But the main problem is to determine the usable design values of material properties (design yield and ultimate strength) to utilize them for the reliable static re-design of existing structure under actual loading actions. Some problems indicated above have been shown on the example of the material analysis of steel load-carrying structure of slaughterhouse aged more than 100 years. This analysis has been performed recently within the framework of the construction exploration in connection with the intended revitalization of historical “industrial zone” in the city of Brno, Czech Republic.

Abstract: The parameter of the undisturbed soil cannot be used simply in the engineering for the characteristics varied considerably. So the physics and mechanical characteristics of freeze-thaw soil are very important in the freezing method engineering. The physics and mechanical properties of freeze-thaw soil and undisturbed soil are compared by the experiment. And the data of test are shown that after the samples are frozen and thawed, density, dry density decrease and plastic limit decrease, void ratio increase a little, other physicals are similar. Permeability of mild clay greatly increased. Compressibility of mild clay decrease, but compressibility of fine sand increase. This can be used reference to model test, numerical analysis and project designing.

Abstract: Due to lack of knowledge or incomplete, inaccurate, unclear information in the modeling, simulation, measurement and reliability assessment and design optimization, there are limitations in using only one framework (probability theory) to quantify the uncertainty in a system because of the impreciseness of data or knowledge. In this paper, evidence theory is proposed as an alternative to the classical probability theory to handle the imprecise data situation. In order to alleviate the computational difficulties in the evidence theory based uncertainty quantification (UQ) analysis, a differential evolution based interval optimization for computing bounds method is developed. A typical truss structure with the aleatory and epistemic uncertainties is investigated to demonstrate accuracy and efficiency of the proposed method.

Abstract: In order to solve the conflict multi-objective optimization of truss structures between the structure minimum weight and safety redundancy, the immune clonal selection algorithm based on information entropy was adopted in this paper. Based on the immunology theory, the non-dominated neighbor-based selection, proportional cloning and elitism strategy were introduced in the multi-objective immune clonal selection algorithm (MOICSA) to enhance the diversity, the uniformity and the convergence of the obtained solution. Mathematical models for truss multi-objective optimization design are constructed, in which the information entropy value of bar stress is taken as one of objective functions, and penalty function method was used to deal with violated constraints. Several classical problems are solved using the MOICSA algorithm, and the results compared with other optimization methods. The simulation results show that the method can achieve the effect of multiple-objective optimization successfully.

Abstract: Hazardous Waste Management is a special course offered to students whose major is Environmental Engineering. It is offered to let students know basic knowledge and technologies of hazardous waste (HW) processing and disposal, so that they can solve problems on HW processing and disposal. With increasing development of processing and synthesis of substances, lots of hazardous waste is generated as side-products. As more importance was attached on environment, requirement on hazardous waste management is more stringent than ever before. In order to enhance the competitiveness of undergraduates in using English, it is necessary to develop this course as a bilingual course. This paper first analyzes the basic conditions of this course. Then it proposes a developing plan for the course from the following aspects: adjustment of the course, reorganization of the textbook, teaching method, teaching mode, test database and exercise database and ways to increase teaching quality of this course.

Abstract: In oil refinery there is a variety of physical parameters such as pressure, flow rate and level that need to be measured. A microcontroller system is built based on PIC 16F877A, piezoresistive differential pressure DP sensor (24PC series) and strain gauge DP sensor (IDP-10) with ranges from 0 to 15psi. The results of the microcontroller system showed that; the percentage error for piezoresistive sensor in pressure from 0.43808% to 8.613 %, in flow rate from 0.21929% to 20.340%, and in level from 0.43808% to 2.5789%. While the percentage error for strain gauge sensor from 0.846% to 1.946% for pressure measurement, from 0.1% to 0.4% for flow rate measurement and from 0% to 0.64% for level measurement. The percentage error of the piezoresistive sensor is more than the percentage error of the strain gauge sensor: for pressure measurement by about 6.667%, for flow rate measurement by about 19.94% and for level measurement by about 1.9389%. Fuzzy logic is used to predict the output surface of pressure, flow rate, and level measurements.

Abstract: This paper introduces ultrasonic ranging system which can be applied to avoid obstacle and navigate for mobile robot .This system is composed of AT89S51 single chip microcomputer ,ultrasonic transmitting circuit, ultrasonic receiving circuit, amplifying and filtering circuit , peak value time detecting circuit, environment temperature compensation circuit. The method of echo peak time detection point is used to eliminate the error. It is proved that The maximum range of the system is 10 meter and maximum measurement error can be controlled to± 2 cm or so. This system has such merits as rapid corresponding, high precision, high performance price rate.

Abstract: The report describes an original method of calibrating an autonomous unit of wireless accelerometers manufactured by Microdevices Laboratory, Ltd [1]. Without the use of precision rotary tables, centrifuges, and an independent basement (against vibrations), it is possible to reduce the error caused by the mismatch (not orthogonal)of sensor’s axes. Zero and scale factors of the sensor unit are calibrated with great precision. The calibration of the sensor unit with a measuring range of 2 g, produces the following results: the standard deviation of the vector g, measured in more than 100 different static positions is less than 0.001 g. Thus, the parameters of the initial three-axis accelerometer, used in the block of firm Microdevicelab, improved by more than 50 times.

Abstract: Automatic equipmenttransportation in the wild complex terrain circumstances is very important in rescue or military. In this paper, an accompanying system based on the identification and tracking of infrared LEDmarkers is proposed. This system avoidsthe defect that visible-light identification method has. In addition, this paper presents a Kalman filter to predict where infraredmarkers may appear in the nextframe imageto reduce the searchingarea of infrared markers, which remarkablyimproves the identificationspeed of infrared markers. The experimental results show that the algorithm proposed in this paper is effective and feasible.