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Enzymatic Synthesis of 2-Chloro-1-Phenylethanol with High Optical Purity Xia Xiao-le Wang Yong-hua Li Wen-cheng Yang Bo Wang Xiao-ning Journal of South China University of Technology (Natural Science Edition)    2009, 37 (12): 90-94.   Abstract （2191）      PDF（pc） （352KB）（95611）       Knowledge map    Save Two enantiomers of chiral 2-chloro-1-phenylethanol with high optical purity were synthesized using the enzymatic method, and the kinetic resolution of various lipases were investigated. Moreover, the effects of organic solvent, temperature and water activity on the lipase-catalyzed resolution of （R, S）-2-chloro-1-phenylethanol were analyzed, and the reuse of immobilized enzymes was investigated. The results indicate that a new immobilized lipase from Pseudomonas cepacia marked as Lipase PS IM shows high activity, by which two high-purity enantiomers （eep 99% and ees 99% , respectively） can be separated in n-hexane at 35℃with a water activity of 0. 69; and that the relative activity of Lipase PS IM after five repetitive reactions is still up to 85%. Related Articles | Metrics | Comments（0）

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Stability Analysis of Water-in-Oil Microemulsion System Zou Hua-sheng Chen Jiang-fan Chen Wen-biao Journal of South China University of Technology (Natural Science Edition)    2008, 36 (3): 32-36.   Abstract （1735）      PDF（pc） （273KB）（6013）       Knowledge map    Save In this paper, highly dispersed water-in-oil （W/O） microemulsion with uniform drop size was prepared by using the composite surfactant Tween80-Span80 and by taking cyclohexane as the oil phase. Then, for the purpose of obtaining the maximum solved water, the influences of such factors as the surfactant composition, four alcohol cosurfacants, the temperature and the salinity on the microemulsion stability were investigated by means of visual inspection and conductivity measurement. The optimum conditions for preparing the microemulsion were finally obtained. Experimental results show that, when the mass fraction of Tween80 in the composite surfactant is 60% and the mass ratio of the consurfactant ethanol to the composite surfactant （Km） is 1.0, the best W/O microemulsion system as an ideal microreactor can be prepared, and that, with the increase in temperature, the stable region of the microemulsion in phase diagram decreases and the influence of salinity on the region becomes slight. Related Articles | Metrics | Comments（0）

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Structure and Thermal Properties ofComposite Paraffin/ExpandedGraphite Phase-ChangeMaterial Zhang Zheng-guo Wang Xue-ze Fang Xiao-ming Journal of South China University of Technology (Natural Science Edition)    2006, 34 (3): 1-5.   Abstract （2165）      PDF（pc） （734KB）（5913）       Knowledge map    Save Composite paraffin /expanded graphite phase-change materials ( PCMs) respectively containing 50% (mass fraction, below the same), 60% , 70% and 80% of paraffin were prepared by using paraffin as a latent hea-tstorage material and expanded graphite as a supporting matrix. The structure and thermal properties of PCMs were then characterized by means of SEM and DSC. It is shown that paraffin can be uniformly absorbed into the pore network of expanded graphite, that expanded graphite remains its vermiform structure in PCMs, that the phasechange temperatures of composite PCMs are similar to that of paraffin, and that the latent heat of composite PCMs is equivalent to the calculated values based on themass fraction of paraffin in the composite materials. Moreover, tested results of heat storage and release indicate that the time o f thermal-energy storage and release of the composite PCM containing 80% of paraffin decreases respectively by 69. 7% and 80. 2% , as compared with that of paraffin. Related Articles | Metrics | Comments（0）

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Influence of EDC/NHS Crosslinking on Physicochemical Properties of Collagen Wang Ying-jun Yang Chun-rong Wang Ling-yun Journal of South China University of Technology (Natural Science Edition)    2007, 35 (12): 66-70,96.   Abstract （1522）      PDF（pc） （419KB）（5160）       Knowledge map    Save In order to improve the physicochemical properties of collagen , l-ethyl-3 -( 3 -dimethyl aminopropyl) carbodiimide (EDC) /N -hydroxysuccinimide (NHS) was used as a crosslinking agent for collagen matrices , and the effect of crosslinking agent dosage on the physicochemical properties of collagen was investigated. Then , the measurements of FT -IR , DSC and SEM were performed and the water absorption , the swelling ratio and the collagenase resistance were tested to characterize the physicochemical properties of the collagen before and after the crosslinking. The results demonstrate that , after the crosslinking , the thermal stability , the morphological stability and the enzymatic resistance all improve significantly , and that the disordered microstructure of collagen changes to a dense and ordered state. It is thus concluded that the EDC/NHS crosslinking greatly improves the physicochemical properties of collagen. Related Articles | Metrics | Comments（0）

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Somatic Operation Based on Sensor of Android Mobile Devices Han Di Pan Zhi-hong Journal of South China University of Technology(Natural Science Edition)    2012, 40 (9): 75-80.   Abstract （1338）      PDF（pc） （802KB）（4913）       Knowledge map    Save The context awareness based on the ubiquitous computing has been widely used in our life. In order to realize somatic operations by using a well-established sensing technology on Android mobile devices,this paper devises a new somatic operation system based on Android. In this system,the middleware technology is employed to achieve the communication between the server and the Android mobile devices,including the transmission of the effectively-identified data,the pattern recognition of the user operation and the quantization of the load motion data. Meanwhile,the analog data are acquired through the sensor and are then converted into executive digital commands,thus promoting the sensor development of the Android mobile phone. Experimental results show that the proposed system is of higher accuracy and lower energy consumption and is capable of being used in different situations.Key words: Related Articles | Metrics | Comments（0）

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Experimental Methods of Equiaxial Tension of Hyperelastic Membrane and Corresponding Simulations Luo Hua-an Wang Hua-ming You You-peng Journal of South China University of Technology (Natural Science Edition)    2011, 39 (4): 56-61.   DOI: 10.3969/j.issn.1000-565X.2011.04.010 Abstract （1702）      PDF（pc） （635KB）（4912）       Knowledge map    Save  In this paper,first,an equi-biaxial tensile test apparatus for hyperelastic membrane was developed,and the principle and method of the equiaxial tension test were illustrated.Then,the test conditions and the data processing are both investigated.Finally,three kinds of equiaxial tension methods,i.e.,the ideal tension test,the free-corner tension test and the fixed-corner tension test,were simulated with FEA software ABAQUS.It is found that the error of the fixed-corner tension test in a large tension range is small enough to satisfy the requirements of experiments. Related Articles | Metrics | Comments（0）

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Phase Difference Extraction Based on Four-Step Phase Shifting Cai Chang-qing He Ling-feng Journal of South China University of Technology (Natural Science Edition)    2011, 39 (9): 93-96.   DOI: 10.3969/j.issn.1000-565X.2011.09.016 Abstract （821）      PDF（pc） （795KB）（4767）       Knowledge map    Save Aiming at the phase difference extraction in speckle pattern interferometry,a novel method is proposed based on the four-step phase shifting. In this method,by collecting the four interferometric patterns respectively before and after the object deforming,a novel mathematical expression of the phase difference is theoretically derived,which avoids the high-frequency noise and the false wrapped phase difference of the general four-step phase-shifting method. The proposed method is then tested by using a circumferentially-fixed disk model with a point loading at the centre and is compared with the general four-step phase-shifting method. The results show that the proposed method is significantly superior to the general one in terms of high-frequency noise elimination and image quality improvement,and that it can not only suppress the noise but also maintain the stripe features. Related Articles | Metrics | Comments（0）

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Test and Simulation of Cushioning Composite- Laminated Energy-Absorbing Property of Cylindrical Shells Song Yi Wang Fan Journal of South China University of Technology (Natural Science Edition)    2009, 37 (12): 140-145.   Abstract （655）      PDF（pc） （424KB）（4741）       Knowledge map    Save :According to the kinetics of composite-laminated cylindrical shells subjected to axial impact loads, the cushioning energy-absorbing property of the standard and the petal-triggered GFRP （Glass Fiber-Reinforced Composite）-laminated cylindrical shells are investigated through the quasi-static compression test. Then, by setting up a material model which implements the Chang-Chang failure criterion, the dynamic response process of the shells under drop impact is simulated using ANSYS/LS-DYNA. The simulated results of the normal composite-laminated cylindrical shells accord well with the experimental ones in terms of some key characteristics, and the simulation errors of velocity, displacement, acceleration and peak acceleration are found to be 19.5%, 12. 0%, 6. 4% and 14. 6%, respectively. Moreover, the improvement of triggering mode of the petal-triggered composite-laminated cylindrical shells increases the specific energy-absorbing value, greatly decreases the initial peak load, and prolongs the compression displacement for the peak load. It is thus concluded that the model based on the Chang-Chang failure criterion helps to precisely predict the crushing process and the failure of the material. Related Articles | Metrics | Comments（0）

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High-Efficiency Text Clustering Algorithm Based on Semantic Distance Feng Shao-rong Xiao Wen-jun Journal of South China University of Technology (Natural Science Edition)    2008, 36 (5): 30-37.   Abstract （703）      PDF（pc） （467KB）（4575）       Knowledge map    Save As the existing text clustering algorithms overlook the semantic information between words and possess low calculation accuracy of text similarity,this paper proposes a new text clustering algorithm based on the semantic distance.In this method,the text is analyzed in terms of semantic,and the specific semantic of the text is used to calculate the similarity.Moreover,the nearest neighbor clustering algorithm is adopted,and a second clustering algorithm is presented to overcome the sensitivity of the nearest neighbor clustering algorithm to the input order of the text.According to the similarity weight,some feature words representing the cluster are chosen,which makes the remained feature words similar to the themes of the cluster.Experimental results indicate that the proposed algorithm is of higher clustering precision and recall rate,as compared with the k-Means algorithm based on the vector space model. Related Articles | Metrics | Comments（0）

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Authentication and Key Exchange Scheme Based on SRP-6 Protocol Li Dong Guo He-qing Han Tao Journal of South China University of Technology (Natural Science Edition)    2007, 35 (1): 94-98.   Abstract （392）      PDF（pc） （273KB）（4412）       Knowledge map    Save In order to solve the problem of authentication in Web services , the key exchange mechanism of Secure Rernote Password-6 (SRP- 6) is analyzed , and a new authentication and key exchange scheme named SRP-over-SOAP is proposed. The proposed scheme , which is based on the Simple Object Access Protocol (SOAP) and the SRP-6 , branches out SOAP message and assigns the label of < SRPAuth > to SOAP header. Thus , the SRP au thentication in the transportation of SOAP message can be implemented. Moreover , by applying the proposed scheme to Web services , a bi-directional authentication between the server and the client server can also be imple-mented. Related Articles | Metrics | Comments（0）

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Preparation and Properties of Resistant Starch from Mung Bean Starch Gao Qun-yu Li Su-ling Journal of South China University of Technology (Natural Science Edition)    2011, 39 (4): 88-93.   DOI: 10.3969/j.issn.1000-565X.2011.04.016 Abstract （607）      PDF（pc） （511KB）（4330）       Knowledge map    Save Resistant starches（RS） with high RS content were prepared from mung bean starch respectively via the autoclaving treatments with and without the addition of pullulanase.Then,the effects of the starch slurry content,the enzyme dosage,the debranching time,the retrogradation temperature and the retrogradation time on the formation of RS were analyzed,and the granule morphology,crystalline structure and thermal characteristics of the starch were investigated by means of SEM,XRD and DSC,respectively.The results show that（1） after an autoclaving treatment at 121℃ for 20min,debranching with 50ASPU/g pullulanase at 55℃ for 24h and a storage at 20℃ for 24h,the RS content of the sample was 56.9%;（2） after the debranching and recrystallization,the recrystallized starch granules display irregular shaped fragments,the XRD pattern changes from Type A to Type B,and the degree of crystallization greatly increases from 17.9% to 45.7% in the presence of enzymatic treatment;and（3） the melting temperature,the enthalpy and the thermal stability of RS all increase after debranching and recrystallization. Related Articles | Metrics | Comments（0）

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Gradient-Based Structural Similarity for Image Quality Assessmen Yang Chun-ling Kuang Kai-zhi Chen Guan-hao Xie Sheng-li Journal of South China University of Technology (Natural Science Edition)    2006, 34 (9): 22-25.   Abstract （421）      PDF（pc） （211KB）（4295）       Knowledge map    Save Although the SSIM (Structural Similarity)model,an assessment model of image quality based on the structural information,has been proved to be better than the PSNR(Peak Signal to Noise Ratio)or the MSE(Mean Square Error)model,there still remain some deficiencies in assessing badly blured images.In order to solve this prob-lem,this paper proposes a gradient-based structural similarity(GSSIM)model that takes the gradient as the main strut-tural information of an image.Experimental results show that the proposed GSSIM model is more consistent with human visual system and can assess the quality of blured images more precisely than the SSIM and PSNR (MSE)models. Related Articles | Metrics | Comments（0）

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Precision Analysis of Classical Bending Deflection Formulae of Simply-Supported Beams Yang Yi Liu Ji-ke Journal of South China University of Technology (Natural Science Edition)    2008, 36 (6): 30-34.   Abstract （659）      PDF（pc） （221KB）（4190）       Knowledge map    Save A new deformation mode of the simply-supported beam is presented, which considers not only the deflection and slope but also the plane transmutation in the cross section. Then, the plane bending of the simply-supported beam is analyzed by means of the U-transformation and the four-node rectangular element, and the analytical displacements on the upper and lower surfaces under a concentrated load of magnitude in a two-dimension finite element mode are obtained. The displacements are compared with the deflection calculated on the basis of the material mechanics. Moreover, the applicable field of the classical bending deflection formulae of the simply-supported beam is discussed, and the corresponding precision is quantitatively analyzed. Related Articles | Metrics | Comments（0）

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Matching of Motor and Powertrain Parameters of Electric Vehicle Ji Fen-zhu Gao Feng Journal of South China University of Technology (Natural Science Edition)    2006, 34 (4): 33-37.   Abstract （413）      PDF（pc） （292KB）（4023）       Knowledge map    Save The determining principles of the transmission ratio and the block number of electric vehicle are dis-cussed in this paper.It is discovered that the rated power/torque and the rotating speed of the motor must match the parameters of powertrain.With a type of electric vehicle as the research object,the charts describing the balance between the driving force and the obstruction force are presented and then analyzed by the calculations of the second and the third gearshifts of a manual five-gear transmission.Based on the charts,a single gearshift driving scheme with the heavier mechanical gear transmission being replaced by the constant-ratio one is proposed.Theoretically,the gross mass is lightened and the driving range is increased by the proposed scheme.The gross mass and the driv-ing range of the electric vehicle are finally simulated using the dynamic simulation software of Advanced Vehicle Simulator(ADVISOR).The correctness of the proposed principles and methods for determining powertrain parame-ters is thus verified. Related Articles | Metrics | Comments（0）

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Algorithm to Analyze Overlapping Community Structure of Intersection Networks Zhao Peng Cai Qing-sheng Wang Qing-yi Journal of South China University of Technology (Natural Science Edition)    2008, 36 (5): 19-23.   Abstract （756）      PDF（pc） （263KB）（3943）       Knowledge map    Save The existing algorithms to analyze the community structure are all based on the complex networks with non-intersection structure,and most of them can only analyze the separated community structures rather than to ana-lyze the overlapping and intersecting ones.In order solve this problem,a novel algorithm to analyze the overlapping community structure of intersection network is proposed.The proposed algorithm,IBCPM,is then adopted to analyze the community structure of the user＇s collection intersection network,and the results are further statistically analyzed.The effectiveness and efficiency of the proposed algorithm are finally verified by experiments. Related Articles | Metrics | Comments（0）

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Optimization Design of Filters Based on Parameter Extraction and Space Mapping Chen Jian-zhong Liang Chang-hong Chen Jia Deng Kun Journal of South China University of Technology (Natural Science Edition)    2011, 39 (10): 32-36,73.   DOI: 10.3969/j.issn.1000-565X.2011.10.006 Abstract （3411）      PDF（pc） （366KB）（3767）       Knowledge map    Save In order to improve the design efficiency of microwave bandpass filters,an optimization design method is proposed based on the parameter extraction and the space mapping. In this method,first,the Cauchy-TLS ( Total Least Squares) method is used to obtain the rational fraction models of the filters. Next,by using these models,a fast convergent objective function is constructed to extract the equivalent circuit parameters. Then,according to the principle of the space mapping,the problem of solving the optimal physical dimension of the filter is transformed into a quadratic constrained optimization model,and the corresponding solution is used to guide full-wave simulation of the filters. Finally,a dual-mode circular-waveguide filter is designed and machined,and its optimal physical dimension with ideal response is achieved after six iterations. It is found that the measured results accord well with the simulated ones. Related Articles | Metrics | Comments（0）

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Design of a Modular Robot Platform Zhou Xue-feng Jiang Li Zhu Hai-fei Cai Chuan-wu Guan Yi-sheng Zhang Xian-min Journal of South China University of Technology (Natural Science Edition)    2011, 39 (4): 50-55,61.   DOI: 10.3969/j.issn.1000-565X.2011.04.009 Abstract （529）      PDF（pc） （824KB）（3758）       Knowledge map    Save In order to overcome such shortcoming as low flexibility,poor fault tolerance,poor self-repairing ability as shown in bask-based design of traditional robots,and to reduce the use cost of robots,a modular robot platform is designed.In the investigation,first,the overall design of the modular platform is presented.Then,the design principles and implementations of the hardware and the software of the platform are introduced.Finally,five robots,namely a manipulator,a wheeled mobile robot,a biped walking robot,a wall-climbing robot and a tree-climbing robot,are built for the proposed platform,for which some simulations and experiments are performed.Experimental results show that the proposed modular design method is feasible with high performance. Related Articles | Metrics | Comments（0）

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Parameter Identification and SOC Estimation of Lithium-Ion Battery Pack Used in Electric Vehicles Luo Yu-tao Xie Bin He Xiao-chan Journal of South China University of Technology(Natural Science Edition)    2012, 40 (12): 79-85.   Abstract （452）      PDF（pc） （1209KB）（3524）       Knowledge map    Save Proposed in this paper is a SOC ( State of Charge) estimation method to correct the initial error of SOC of the lithium-ion battery pack used in electric vehicles. The new method employs an algorithm combining the extended Kalman filtering with the Ampere-hour integral method. In the investigation,first,the advantages and disadvantages of several equivalent battery circuit models were analyzed,and the improved PNGV model with double RC parallel networks was selected to perform the parameter identification of a lithium-ion battery. Then,a nonlinear dynamic model of the battery in the state-space form was constructed with the help of the improved PNGV model,and the relationship between the open circuit voltage and the corresponding SOC of the battery was analyzed based on the polynomial fitting. Finally,some experiments in the conditions of constant-current pulse discharge and ECE15 were carried out. The results indicate that the proposed algorithm effectively corrects the initial error of SOC and guarantees the estimation accuracy of SOC. Related Articles | Metrics | Comments（0）

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Design of Pilot Signals in OFDM Systems Yang Wei Sun Le Xu Chang-long Journal of South China University of Technology (Natural Science Edition)    2011, 39 (7): 63-69.   DOI: 10.3969/j.issn.1000-565X.2011.07.011 Abstract （530）      PDF（pc） （996KB）（3235）       Knowledge map    Save This paper deals with the channel estimation technology applied to orthogonal frequency division multiplexing ( OFDM) systems and proposes a novel method to design the optimal pilot pattern. In this method,first,the spacing in the time and the frequency domains between two pilot symbols are determined respectively according to the maximum multi-path delay and Doppler frequency shift. Then,all possible pilot patterns are listed by using the exhaustive method. Finally,the optimal pilot pattern is obtained according to the mean square error between the estimated and the actual channels. In addition,the proposed method is applied to a long-term evolution ( LTE) system to verify its correctness and effectiveness,and the superiority of the optimal pilot pattern is verified by simulation curves. From the simulated results,it is found that,as compared with the system using the original LTE pilot pattern,the system using the optimal pattern is of higher BER ( Bit Error Rate) performance under the Vehicular Test A channel. Related Articles | Metrics | Comments（0）

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Judgement Characteristics and Quantitative Index of Suitable Block Scale Huang Ye-qing Sun Yi-min Journal of South China University of Technology(Natural Science Edition)    2012, 40 (9): 131-138.   Abstract （452）      PDF（pc） （3600KB）（3119）       Knowledge map    Save By analyzing the connotation of blocks,the judgement characteristics of a suitable block scale are summed up and are used to perform a quantitative research on the suitable block scale. Then,according to the statistical data and the contrast analysis of the block scales of ninety urban central districts abroad,a quantitative index of suitable block scale is determined. The results show that,in urban design,the reasonable block scale should be controlled at less than 200m; and that,as the block scale in Chinese cities tends to become larger,a more suitable scale should be set within the range of 150 ～ 200m. The presented quantitative index can be used as a general criterion for the judgement of optimal block scale and it provides a reference for determining suitable block scale in urban design. Related Articles | Metrics | Comments（0）