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15 January 2005, Volume 26 Issue 1 Previous Issue    Next Issue
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Variable structure model-following control for a class of uncertain linear composite systems Liu, Hui-Ming (1); Jing, Yuan-Wei (1); Zhang, Si-Ying (1) 2005, 26 (1):  205-208.  DOI: - Abstract ( 200 )   HTML   PDF (161KB) ( 432 )   The model-following control problem is discussed for a class of uncertain linear composite systems with parametric perturbation and exterior disturbance. In view of the interconnected terms which play an indispensable role in composite systems, a new idea is put forward that the reference model is chosen according to the expected performance indices with the interactions among different sub-systems taken fully into account so as to add the interconnected terms to the reference model. Based on the assumption of the uncertainty satisfying the bounded and matched conditions, a new robust decentralized variable structure model-following controller is proposed to ensure the global asymptotic stability of the uncertain linear composite systems by means of Lyapunov method. The proposed control law is designed concisely and easy to realize. Simulation results show the effectiveness of the proposed method. References | Related Articles | Metrics

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Robust control for uncertain nonlinear composite systems based on neural networks Liu, En-Dong (1); Jing, Yuan-Wei (1); Zhang, Si-Ying (1) 2005, 26 (1):  209-212.  DOI: - Abstract ( 207 )   HTML   PDF (165KB) ( 378 )   Based on neural networks, a new robust control methodology is presented for nonlinear uncertain composite systems of which the nonlinearities are assumed unknown. The unknown disturbance and interconnected terms are approximated using neural networks. The nominal system is considered. to develop a nominal controller. Then, the unknown disturbance and interconnected terms are taken into account to design correction control signals and add them to the nominal controller, thus the actual system is guaranteed to be uniformly ultimately bounded. In this way the control signals are smooth without the requirement for knowing the upper bounds on the optimal weight values and modeling error in advance. Numerical simulation studies are used to illustrate and clarify the approach. References | Related Articles | Metrics

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Sufficient condition for stability with H∞ performance for linear discrete-time switched systems Song, Zheng-Yi (1); Zhao, Jun (1) 2005, 26 (1):  213-216.  DOI: - Abstract ( 262 )   HTML   PDF (185KB) ( 668 )   The problem of stability with H∞ performance for a class of linear discrete-time switched systems is discussed under the action of arbitrary switching. The system taken into consideration consists of several linear discrete-time subsystems of which each is stable with H∞ performance. It is well known that the switched system may be unstable under some switching actions between asymptotically stable subsystems, so it is not certainly stable with H∞ performance under the action of any switching. Based on the known bounded real lemma, a sufficient condition for the solvability of the problem is given in terms of linear matrix inequalities (LMIs) by using common Lyapunov function method. A simulation of a practical example is conducted to show the effectiveness of the result. References | Related Articles | Metrics

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Robust dynamic output feedback H∞ control of singular systems with varying-delays and nonlinear parameter uncertainty Yang, Fan (1); Zhang, Qing-Ling (1) 2005, 26 (1):  217-220.  DOI: - Abstract ( 244 )   HTML   PDF (310KB) ( 498 )   The design of robust dynamic output feedback robust H∞ controller for a class of singular systems with varying state-delay, input-delay and nonlinear parameter uncertainty is considered. The parameter uncertainties are assumed nonlinear and norm bounded. Combining the linear matrix inequality with Lyapunov function on suitable conditions, the design method and existent sufficient conditions are given to a robust dynamic output feedback controller by which the time-delay singular closed-loop system is admissible, i.e., regular, stable and impulse-free, and the transfer function from exogenous disturbance to output satisfies a prescribed H∞ performance index for the given parameter uncertainty. Furthermore, it is shown that the robust dynamic output feedback controller can be constructed in terms of the feasible solutions to a certain linear-matrix inequalities and extended to the cases involving multiple time-varying delays. An example is given to illustrate the effectiveness of the proposed method. References | Related Articles | Metrics

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Design of adaptive observer for fault estimation Wang, Zhan-Shan (1); Zhang, Hua-Guang (1) 2005, 26 (1):  221-224.  DOI: - Abstract ( 257 )   HTML   PDF (172KB) ( 1181 )   Fault estimation for linear systems based on a class of adaptive observers is investigated. The system states and faults can both be estimated by such adaptive observers. Utilizing the H∞ tracking performance, the design procedure and condition of stability of the adaptive observers are given. The fault estimation error is irrelevant to the magnitude of fault but relevant to the change rates of fault and H∞ tracking index. Therefore, the estimated fault can approximate to the real fault to any degree of accuracy. A simulation of sensor fault estimation is carried out for induction motor to verify the effectiveness of the proposed method. References | Related Articles | Metrics

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Application of quaternions in surgery navigation system Yang, Yi-Lu (1); Xu, Xin-He (1) 2005, 26 (1):  225-228.  DOI: - Abstract ( 219 )   HTML   PDF (183KB) ( 891 )   It was found that quaternions can play an alternative and compact role in surgery navigation system (SNS), to represent rotation. Locating something in different coordinate systems involves the mapping transformation between them. The application of quaternions in the mapping transformation between SNS coordinates and that of spatial registration in SNS are theoretically discussed in detail. The result of simulation shows that the application of quarternions to SNS can solve successfully the two difficult technological problems in SNS, i.e., spatial locating and registration. Both have been used successfully in the SNS model demonstration system NEU-IGSS which was designed and developed by ourselves. References | Related Articles | Metrics

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Food-chain algorithm and its application to supply-chain operation management problems Yu, Hai-Fei (1); Wang, Ding-Wei (1) 2005, 26 (1):  229-232.  DOI: - Abstract ( 285 )   HTML   PDF (181KB) ( 927 )   Based on artificial life principle of 'bottom to up model' and the food-chain phenomena in ecology, a new type of artificial life based algorithm is proposed and referred to as food-chain algorithm. Then, the algorithm is applied to solving the supply-chain operation management problems involving partner selection and relevant productive capacity in an enterprise alliance. Both how an enterprise alliance selects its partners to form the alliance and how a member enterprise adjusts its productive capacity to meet the future market demand can be simulated by the food-chain algorithm. The algorithm can effectively figure out the distributive problems as above. In addition to them, the algorithm can be applied to other problems of supply-chain management, such as the location-allocation problem. References | Related Articles | Metrics

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Robust RLS adaptive beamforming algorithm Wang, Jin-Kuan (1); Song, Xin (1); Wang, Han (1) 2005, 26 (1):  233-235.  DOI: - Abstract ( 316 )   HTML   PDF (108KB) ( 802 )   Under the circumstances of multipath propagation, the performances of existing adaptive array algorithms are known to degrade substantially in the presence of even slighter mismatches between the actual and presumed array responses to the desired signal. Similar types of degradation can take place when the signal array response is known precisely but the training sample size is small. The novel approach to robust adaptive beamforming is proposed in the presence of the signal steering vector mismatches. The robust RLS adaptive beamforming algorithm provides excellent robustness against the signal steering vector mismatches and small training sample size, offers faster convergence rate, makes the mean output array SINR consistently close to the optimal one and improves the unitary mismatch. Computer simulations demonstrate a visible performance gain of the proposed robust RLS algorithm. References | Related Articles | Metrics

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Study on architecture of internet access server for non-PC devices Xu, Feng (1); Chen, Yan (2); Zhao, Hai (1); Han, Guang-Jie (1) 2005, 26 (1):  236-239.  DOI: - Abstract ( 232 )   HTML   PDF (187KB) ( 579 )   The architecture of non-PC devices' Internet access server-Webit 2.0 is proposed and implemented to realize the networked and intellectualized management of non-PC devices in the embedded Internet environment. Webit 2.0 simplifies the conventional TCP/IP protocol stack based on embedded real-time operating system, and realizes the function of embedded Web server in non-PC devices. Furthermore, SNMP and SMTP protocols are added to Webit 2.0, thus implementing the network management in non-PC devices so as to enable remote users to access transparently the devices over Internet with Web browser and accomplish such operations as device monitoring, real-time management, emergency alarm and download the device driver. Webit 2.0 can therefore provide the possibility and technical assistance for the implementation of information management of industrial equipment and intelligent home systems. References | Related Articles | Metrics

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Network performance management model through mobile agent Zheng, Hong-Fang (1); Chen, Jiao-Rui (1); Wang, Guang-Xing (1) 2005, 26 (1):  240-242.  DOI: - Abstract ( 248 )   HTML   PDF (126KB) ( 434 )   To overcome the shortcomings of traditionally initial SNMP network management, the network performance management model through mobile agent was presented. The model paid attention to the popularity of SNMP and integrated the technology of mobile agent into one so as to resolve the problems of network resource occupation and poor dynamic extensibility, thus improving the efficiency of network management. Its construction and work procedure were illustrated and compared with those of the traditionally initial SNMP. A conclusion was drawn that this model has such advantages as shorter response time, less bandwidth consumption, better adaptability and more intelligent than the initial one, as proved via simulation and comparative analysis. References | Related Articles | Metrics

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Construction and analysis of quaternion fractal set in a simplex space Yu, Hai (1); Xu, Zhe (1); Zhu, Wei-Yong (1) 2005, 26 (1):  243-246.  DOI: - Abstract ( 257 )   HTML   PDF (179KB) ( 934 )   The paper uses the escape-time algorithm to construct a series of M-J sets and estimates the boundary of the M set of the quaternion, based on the characteristics of quaternion in higher dimensional dynamic space. The corresponding relationship between 4-D Bannach space and 3-D Euclid space is given through a projection transform in simplex coordinate system and, further, the relationship is used to get the mapping of the M-J set of quaternion in a 3-D space. A constructive exploration and trial pre thus provided for the research and development of fractal theory in multidimensional dynamic space. References | Related Articles | Metrics

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Approach to inferring relationship between different autonomous systems from routing table Wang, Da-Dong (1); Wang, Hong-Jun (2); Wang, Rui-Jun (1); Gao, Yuan (1) 2005, 26 (1):  247-250.  DOI: - Abstract ( 244 )   HTML   PDF (146KB) ( 540 )   An approach to inferring relationship between different autonomous systems (AS) from border gateway protocol (BGP) routing tables is proposed. Analyzing BGP input and output routing policies constrained by the AS relationships, an AS path structure is obtained in form of a sequence of AS relationships. The composing rules of AS paths are used to infer AS relationships from the context of the sequence of AS relationships. According to the characteristics of AS path structure as shown in BGP routing tables of different hierarchical ASs, different inference rules are used separately in the relevant BGP routing tables for top-tier ASs and other ASs. The effect due to misconfiguration is considered with several parameters used to infer AS relationships. The algorithm is tested on publicly available BGP routing tables, by which over 80% of the AS relationships could be inferred directly from routing tables for top-tier ASs. A comparison between the results of the ones and another similar algorithm verifies that the algorithm is effective. References | Related Articles | Metrics

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Effects of preparation conditions on TiO2 thin film's microstructure and photocatalytic characteristics Yang, Jia-Long (1); Wang, Fu (1); Zuo, Liang (1); Yi, Gu-Chul (2) 2005, 26 (1):  251-254.  DOI: - Abstract ( 256 )   HTML   PDF (203KB) ( 473 )   Uniform TiO2 films have been prepared on silicon substrates by MOCVD and sol-get processes separately. XRD, FE-SEM and AFM were employed to investigate the characteristics of the TiO2 films, including their crystallinities, microstructures and morphologies. In addition, the aqueous orange II was used to investigate their photo-catalytic degradation properties. Effects of different preparation conditions on their crystallinities and photo-catalytic activities were compared. The results showed that the effect of film preparation temperature on the crystallinities and microstructures is considerable, and the films deposited by MOCVD exhibit a higher efficiency in dye solution degradation than that of the films impregnated by sol-gel. References | Related Articles | Metrics

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Effect of low frequency electromagnetic field on the horizontal direct chill casting 7075 aluminum alloy Zhao, Zhi-Hao (1); Cui, Jian-Zhong (1); Zuo, Yu-Bo (1); Zhang, Hai-Tao (1) 2005, 26 (1):  255-258.  DOI: - Abstract ( 274 )   HTML   PDF (134KB) ( 761 )   The influence of low frequency electromagnetic field on ingot surface quality and as-cast microstructure in horizontal direct chill (HDC) casting process were investigated experimentally. The casting surfaces and as-cast microstructures of the ingots by conventional HDC and low frequency electromagnetic HDC casting were compared. The results show that low frequency electromagnetic field can significantly reduce the surface defects and refine the as-cast microstructures. Further more, increasing electromagnetic intensity and decreasing frequency are both beneficial to the improvement of ingot quality. The optimal number of ampere-turns and frequency available to the experiments are found to be 10000 and 30 Hz, respectively. References | Related Articles | Metrics

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Effect of heat treatment parameters on tertiary recrystallization of cross-shear rolled ultra-thin silicon steel strips Gao, Xiu-Hua (1); Qi, Ke-Min (1); Qiu, Chun-Lin (1); Ye, He-Zhou (1) 2005, 26 (1):  259-262.  DOI: - Abstract ( 360 )   HTML   PDF (734KB) ( 564 )   The 0.3 mm commercial grain-oriented silicon steel sheets were rolled further under 0.1 mm in gauge by conventional rolling (CR) and cross shear rolling (CSR) separately, then the finished strips were annealed in furnace in different atmospheres for tertiary recrystallization. Effects of heat treatment parameters, such as annealing temperature, atmosphere, holding time and heating rate, on the magnetic properties and tertiary recrystallization behavior of the ultra-thin grain-oriented silicon steel strips were investigated. The results show that the magnetic properties achieved in vacuum are better than those in hydrogen atmosphere with other technological parameters kept the same, and the magnetic properties become higher with improved structure after tertiary recrystallization under conditions of higher annealing temperature, longer holding time, and higher heating rate. References | Related Articles | Metrics

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Predicting the onset of austenite-ferrite transformation during hot deformation of low carbon and Nb-V microalloyed steels Xu, Yun-Bo (1); Yu, Yong-Mei (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2005, 26 (1):  263-266.  DOI: - Abstract ( 240 )   HTML   PDF (193KB) ( 982 )   The influence of hot deformation process on austenite-ferrite transformation was investigated to predict the starting temperature of ferrite precipitation of low carbon steels during deformation (Ar3d) and the starting transition temperature of Nb-V microalloyed steels during continuous cooling (Ar3). The results indicate that the lower the C or Mn content, the higher the Ar3d temperature under the same deformation conditions, and Ar3d increases with the increase of strain amount or the decrease of strain rate for the same steel grade. On the other hand, Ar3 decreases with the increase of cooling rate and increases due to deformation. The simulated results were found in agreement with experimental ones, which implied that such a theoretical approach can be used to model the transformation process above mentioned. References | Related Articles | Metrics

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Primary research on preparation of boron powder by self-propagating high-temperature synthesis with a stage of metallurgy Dou, Zhi-He (1); Zhang, Ting-An (1); Wang, Yan-Li (1) 2005, 26 (1):  267-270.  DOI: - Abstract ( 254 )   HTML   PDF (186KB) ( 926 )   A new technique named self-propagating high-temperature synthesis with a stage of metallurgy was proposed to prepare boron powder. The adiabatic temperature (Tad) in B2O3-Mg reaction system was calculated to be 2604 K, through which the thermodynamic data of correlative reactions were analyzed to determine the feasibility of the self-propagating high-temperature synthesis reaction consequently. The DTA results indicate that the apparent active energy of the exothermic peak of B2O3-Mg reaction system is 903.75 kJ·mol-1 with reaction order equal to 1, and the XRD results show that the combustion products are composed mainly of MgO, Mg3B2O6 and B2O3. Thus the three-step leaching conditions were confirmed. The purity of boron powder can be up to 92.43% as indicated by spectral and chemical analyses. Its mean grain size is 0.5-0.8 μm. References | Related Articles | Metrics

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Preparation of LaB6 micropowder by self-propagating high-temperature synthesis and characterization Zhang, Ting-An (1); Dou, Zhi-He (1); Yang, Huan (1) 2005, 26 (1):  271-273.  DOI: - Abstract ( 228 )   HTML   PDF (255KB) ( 781 )   LaB6 micropowder was prepared by self-propagating high-temperature synthesis (SHS). SHS process in which the thermally explosible and leachable products were checked by XRD, then a two-step leaching procedure was therefore confirmed. The LaB6 prepared was analyzed and characterized by TEM, spectral analysis, SEM and granularity analyzer. The results indicate that the thermally explosible products consist of LaB6, MgO and bits of Mg3B2O6 and LaOCl, and that the single pure phase LaB6 can be obtained using HC1 then H2SO4 in an interlacing way in leaching process. The crystal lattice constant of LaB6 was calculated as a = 0.4148 nm, with its purity lower than 99% and the mean grain size is 1.92 μm. References | Related Articles | Metrics

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Combustion synthesis of α-Fe2O3 nanoparticles and its characterization Chu, Gang (1); Zhai, Xiu-Jing (1); Fu, Yan (1); Bi, Shi-Wen (1) 2005, 26 (1):  274-276.  DOI: - Abstract ( 225 )   HTML   PDF (290KB) ( 856 )   The nanocrystalline α-Fe2O3 was prepared successfully by the reaction of polyvinyl alcohol (PVA) with ferric nitrate in combustion synthesis, where PVA is complexing agent. The effect of material proportioning on products and the nanocrystalline α-Fe2O3 were investigated experimentally by TEM, FT-IR and XRD. The results show that the product's particle edges are smooth and in uniform particle size distribution with full reaction of combustion when the mole ratio of ferric nitrate to PVA is 1 to 0.5, and the products present red granular substances. Thus, the products got from phenanthroline at 150°C are calcined at 450°C for 2 h so as to obtain nanocrystalline α-Fe2O3. The results of XRD and IR show that the organic fractions have completely been discomposed. By TEM and XRD for particle-size, the grain size is measured in the range from 25 nm to 40 nm. References | Related Articles | Metrics

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Application of modified genetic algorithms in the compressor optimization Tian, Fang (1); Xie, Li-Yang (1); Tao, Ke (2); Wang, Jie (2) 2005, 26 (1):  277-280.  DOI: - Abstract ( 208 )   HTML   PDF (1050KB) ( 453 )   Based on conventional genetic algorithms, a beneficial modification is done in some aspects to enable them to avoid inherent prematurity and getting bogged down in local optimization. Hybrid encoding method is introduced to make the algorithm more practical. Recombination and screening operators used in forming virgin population will make the distribution of initial solutions more reasonably so as to benefit the improvement of computation efficiency and convergence of the algorithm. In the implementation of the algorithm the mixed genetic operators are selected suitable for both binary coding and real value coding. The modified genetic algorithm has been used in parametric optimization of a sliding-vane compressor, by which the result shows that the modified genetic algorithms is reliable and efficient, as proved by the reasonable parameters. References | Related Articles | Metrics

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Fault diagnosis based on wavelet analysis for low-speed heavy-duty roller bearing Wang, Nan (1); Sun, Feng-Jiu (1); Chen, Chang-Zheng (2) 2005, 26 (1):  281-283.  DOI: - Abstract ( 221 )   HTML   PDF (110KB) ( 772 )   In view of engineering applications, the separation of signal from noise by wavelet analysis is studied for the fault diagnosis system of low-speed heavy-duty roller bearings. By virtue of the features of multi-level and multi-frequency band of wavelet decomposition and wavelet restructuring technique, a simple, accurate and practical fault diagnosis method is developed. The new method is available to find out some troubles, which cannot be found by other ways, such as the impact/wear between rollers, and inner and/or outer race. Its advantage and availability have been proved by actual disassembling of a low-speed high-duty bearing used for a ladle turntable, during which three damaged bearing rollers were found in outer ring with the raceway worn out. An impact/wear fault characterized by low frequency was thus diagnosed successfully. The result indicates that the wavelet analysis can extract effectively weak signals or separate them from noise and that it can make up for the deficiency of frequency spectrum analysis. References | Related Articles | Metrics

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Intelligent fault diagnosis model based on rough sets and decision tree theory Wang, Qing (1); Ba, De-Chun (1); Wang, Xiao-Dong (1) 2005, 26 (1):  284-287.  DOI: - Abstract ( 205 )   HTML   PDF (245KB) ( 537 )   Rough sets and decision tree theory are introduced in complicated intelligent fault diagnosis system (CIFDS). A rough-decision fault diagnosis model is thus developed to ensure diagnosis precision and speed up the implementation of CIFDS. The model can extract rules directly from reduced decision table. Rough sets theory as a new mathematical tool is used to deal with inexact and uncertain knowledge for pattern recognition. The target is mainly to remove redundant information and seek for reduced decision tables. As a quickly learning theory and classification tool, decision tree is used to extract rules directly from reduced decision table so as to acquire satisfactory result. An example is given to show how to apply the intelligent fault diagnosis to RH-KTB vacuum metallurgical system. The effectiveness of the algorithm is therefore proved through the exemplification. References | Related Articles | Metrics

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Biosorbility of Jilin-Changbai diatomite to beer saccharomycete biomass Zhu, Yi-Min (1); Shen, Yan-Bai (1); Wei, De-Zhou (1); Lang, Xian-Ming (2) 2005, 26 (1):  288-291.  DOI: - Abstract ( 241 )   HTML   PDF (209KB) ( 984 )   The biosorption of beer saccharomycete biomass by white diatomite from Changbai Mountain Area in Jilin Province was investigated experimentally. The results show that such a biosorbent has favorable adsorbing effect on beer saccharomycete biomass, and both the adsorbent and adsorbate come in equilibrium within 20 minutes. When the pH value is 7.5 the diatomite shows the best biosorbing effect, and when the amount of diatomite used is 20 g/L with the concentration of beer saccharomycete biomass up to 40 g/L the biosorbing rate is 64% at which the loading amount of the diatomite is 160 mg/g. The biosorption is affected not much by temperature, and it is available to perform biosorption at room temperature. According to the test results, the particles of Jilin-Changbai diatomite is fine with large specific surface area and a bit of impurities. The dominant kinds of algae of the diatomite are small ring and straight chain algae, which provide clear and intercommunicating surface porosity with even pore arrangement. So, the diatomite is naturally a good adsorbent. References | Related Articles | Metrics

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Experimental investigation on relation between electrical conductivity and strain of concrete Wu, Xian (1); Li, Xiu-Mei (2); Wang, Shu-Hong (1); Liu, Zhi-Yang (1) 2005, 26 (1):  292-295.  DOI: - Abstract ( 261 )   HTML   PDF (837KB) ( 674 )   Electrically conductible concrete formed by adding graphite into common concrete possesses good mechanical and electrical properties of which the specimens were tested for their conductivity and mechanical properties by direct-current measurement in the whole process under the actions of single and cyclic loading. The results show that the conductivity measured by DC is easy to do and stable, by which the stress-strain and conductivity-strain relationships are obviously correspondent with each other and the changes in conductivity and stress are almost synchronous, i.e., the conductivity changes a little when stress does. Furthermore, the peak values of conductivity occur near those of stress: 53% before those of stress, 27% at the same time and 20% after them. The curves of the process of conductivity-strain relationships shows small discretization, with the slope of curves' ascending portion in a range from 74.1° to 86.6°. The change of conductivity can represent how the concrete has been damaged intrinsically. References | Related Articles | Metrics

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Forecast based on BP network for P-Δ curves generated from joints of a steel reinforced high-strength concrete frame Xu, Ya-Feng (1); Jia, Lian-Guang (2); Wang, Lian-Guang (1); Liang, Li (1) 2005, 26 (1):  296-298.  DOI: - Abstract ( 186 )   HTML   PDF (713KB) ( 481 )   Based on the testing results of 5 joints at a steel reinforced high-strength concrete column/reinforced high-strength concrete girder frame, some P-▵ curves have been generated under the action of low-frequency cyclic load. Based on the principle of BP neural network, a model is developed by way of setting up the input, implicit and output layers with input and output cells and number of nodes or joints of implicit level all determined. Then, the network is trained up according to some given data to enable it to serve the functions of analysis and judgement so as to forecast the P-Δ curves generated from the joints of a steel reinforced high-strength concrete frame. The results show the feasibility of the method proposed. References | Related Articles | Metrics

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Bearing capacity study of cement-mixed soil pile under environmental erosion Ning, Bao-Kuan (1); Liu, Bin (1); Chen, Si-Li (2) 2005, 26 (1):  299-302.  DOI: - Abstract ( 201 )   HTML   PDF (155KB) ( 927 )   Some testings were done under different conditions of environmental erosion, including water and chemical solutions with different concentrations and pH values, to simulate the erosion effect on the cement-mixed soil of which the mixing ratio is specified and the specimens were sampled from the silty clay soil about 3 m deep under a roadbed. The test of unconfined compression strength of cement-mixed soil was carried out with the specimens cured for 90 days. A conclusion showed that the strength of cement-mixed soil decreased in acid and high strength solutions. On the contrary, strength increased evidently in alkaline environment. Therefore, the design formula of upright bearing capacity of cement-mixed soil pile is modified due to environmental erosion, and a coefficient named environmental effect factor is proposed with its range of value discussed. References | Related Articles | Metrics

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Tests and research on behaviour of reinforced bond in reinforced block masonry Liu, Ming (1); Liu, Bin (1); Huang, Cheng-Kui (2); Jiang, Shao-Fei (3) 2005, 26 (1):  303-306.  DOI: - Abstract ( 147 )   HTML   PDF (151KB) ( 471 )   Based on the results of 12 sets of pull-out tests of mortar specimens, the relationship between bond stress and slip is obtained to determine each and every phase of the failure process of anchoring bars, including microslip, crack-oriented slip, splitting, slip reducing and residual slip. The effects of mortar strength, anchorage length and bar diameter on the performance of the reinforced bond specially used in the tests are discussed. Testing results indicate that, under the condition the ratio l/d is given, the bond strength increases with mortar strength, and decreases with the increase of anchorage length/bar diameter. In view of the pull-out splitting strength of the mortar used and relative anchorage length, the least square method is used in combination with statistical regression to give a formula characterizing the bond strength. References | Related Articles | Metrics