By means of an abstract continuation theorem, the existence criteria are established for the positive periodic solutions of a neutral functional differential equation d N d t=N(t)[a(t)-β(t)N(t)-b(t)N(t-σ(t))-c(...By means of an abstract continuation theorem, the existence criteria are established for the positive periodic solutions of a neutral functional differential equation d N d t=N(t)[a(t)-β(t)N(t)-b(t)N(t-σ(t))-c(t)N′(t-τ(t))].展开更多
This paper summarizes several automatic text categorization algorithms in common use recently, analyzes and compares their advantages and disadvantages. It provides clues for making use of appropriate automatic classi...This paper summarizes several automatic text categorization algorithms in common use recently, analyzes and compares their advantages and disadvantages. It provides clues for making use of appropriate automatic classifying algorithms in different fields. Finally some evaluations and summaries of these algorithms are discussed, and directions to further research have been pointed out. Key words text categorization - naive bayes - KNN - SVM - neural network CLC number TP 391 Foundation item: Supported by the National Natural Science Foundation of China (70031010) and the Research Foundation of Beijing Institute of TechnologyBiography: SHI Yong-feng (1980-), male, Master candidate, research direction: web information mining.展开更多
Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW_ 11O_ 39Ni(H_2O) 6-(SiNiW_ 11) and {SiW_ 11O_ 39Mn(H_2O) 6-}(SiMnW_ 11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon...Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW_ 11O_ 39Ni(H_2O) 6-(SiNiW_ 11) and {SiW_ 11O_ 39Mn(H_2O) 6-}(SiMnW_ 11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-_3 and NO-_2 were comparatively studied.展开更多
An open-loop fiber optic gyro (FOG) testing system is designed. The noise characteristic of open-loop fiber optic gyro signals is analyzed. The wavelet eliminating noise method is discussed and compared with other met...An open-loop fiber optic gyro (FOG) testing system is designed. The noise characteristic of open-loop fiber optic gyro signals is analyzed. The wavelet eliminating noise method is discussed and compared with other methods, such as smoothing and low-pass filter methods. Results indicate that the wavelet eliminating noise method can satisfy the measuring demand of the FOG weak output signal with noise disturbing. The wavelet analysis method can efficiently eliminate the noise and reserve the information of the signal. The eliminating noise effect of using different wavelet base functions is compared. The effectiveness of multiresolution wavelet analyses of eliminating noise is proved by experimental results.展开更多
The explicit form of the evolution operator for the three-atom Tavis-Cummings model is given. The atoms can be entangled through their interaction with a thermal field. The degree of entanglement depends on the mean p...The explicit form of the evolution operator for the three-atom Tavis-Cummings model is given. The atoms can be entangled through their interaction with a thermal field. The degree of entanglement depends on the mean photon number of the thermal field and the initial state of the atoms.展开更多
An improved heuristic ant-clustering algorithm(HAC)is presented in this paper.A device of ’memory bank’ is proposed,which can bring forth heuristic knowledge guiding ant to move in the bi-dimension grid space.The de...An improved heuristic ant-clustering algorithm(HAC)is presented in this paper.A device of ’memory bank’ is proposed,which can bring forth heuristic knowledge guiding ant to move in the bi-dimension grid space.The device lowers the randomness of ants’ moving and avoids the producing of"un-assigned data object".We have made some experiments on real data sets and synthetic data sets.The results demonstrate that HAC has superiority in misclassification error rate and runtime over the classical algorithm.展开更多
Gas phase selective catalytic oxidation of toluene to benzatdehyde was studied on V_2O_5-Ag_2O/η-Al_2O_3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM, and FT-IR. The catalytic re...Gas phase selective catalytic oxidation of toluene to benzatdehyde was studied on V_2O_5-Ag_2O/η-Al_2O_3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM, and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V+Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No. 4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzaldehyde were higher than those on the undoped catalyst. This was attributed to the disordered structure of V_2O_5 lattice of the K-doped catalyst and a better interracial contact between the particles.展开更多
The compound of tetraacetyldibenzylhexaazaisowurtzitane (TADBIW) is an important precursor of synthesizing the high energetic dense compound of hexanitrohexaazaisowurtzitane (HNIW). We can obtain TADBIW by using hydro...The compound of tetraacetyldibenzylhexaazaisowurtzitane (TADBIW) is an important precursor of synthesizing the high energetic dense compound of hexanitrohexaazaisowurtzitane (HNIW). We can obtain TADBIW by using hydrogenolysis of hexabenzylhexaazaisowurtzitane (HBIW). In the process of hydrogenolysis of HBIW, it will generate a variety of intermediates, one of them is the compound of triacetyltribenzylhexaazaisowurtzitane (TATBIW). We have synthesized the title compound and prepared its single crystal. In the paper, the crystal and molecular structure of TATBIW·0.5H2O is described. Its crystal belongs to the triclinic and space group P-1. The cell is comprised of two TATBIW and one water molecules. The success of synthesizing TATBIW can help us to research the mechanism of the reduction of HBIW and produce high yields of the end products.展开更多
Safety incentive mechanism and corresponding motivation avenues are helpful and important for the scientific safety management in coal mine. With the help of modern systematic analysis method, the efficacy of safety i...Safety incentive mechanism and corresponding motivation avenues are helpful and important for the scientific safety management in coal mine. With the help of modern systematic analysis method, the efficacy of safety incentive mechanisms is discussed in detail. The research shows that more effective avenue to reduce accident is to differently use motivation measures in practice.展开更多
The control of single pneumatic muscle actuator is studied, as one basic partof research on the parallel-robot arthrosis actuated by pneumatic muscle actuators. Experimentsshow that a self-modified fuzzy-PID controlle...The control of single pneumatic muscle actuator is studied, as one basic partof research on the parallel-robot arthrosis actuated by pneumatic muscle actuators. Experimentsshow that a self-modified fuzzy-PID controller is obviously effective for its position servo and asimple PID controller is good for its force track.展开更多
We have investigated the use of flash evaporation, headspace solid-phase microextraction (HS-SPME) and steam distillation (SD) as sample concentration and preparation techniques for the analysis of volatile constituen...We have investigated the use of flash evaporation, headspace solid-phase microextraction (HS-SPME) and steam distillation (SD) as sample concentration and preparation techniques for the analysis of volatile constituents present in Houttuynia cordata Thunb. The samples were analyzed by gas chromatography (GC) and identified by mass spectrometry (MS). Comparison studies were performed. It was found that the results obtained between Headspace solid-phase microextraction HS-SPME and SD techniques were in good agreement. Seventy-nine compounds in Houttuynia cordata Thunb were identified by MS. In flash evaporation, thirty-nine compounds were identified. Discrimination in the response for many constituents studied was not observed, which can be clearly observed in SD and HS-SPME techniques. As a conclusion, HS-SPME is a powerful tool for determining the volatile constitutes present in the Houttuynia cordata.展开更多
Entropy maximization thresholding is a simple, effective image segmentation method. The relation between the histogram entropy and the gray level of an image is analyzed. An approach, which speeds the computation of o...Entropy maximization thresholding is a simple, effective image segmentation method. The relation between the histogram entropy and the gray level of an image is analyzed. An approach, which speeds the computation of optimal threshold based on entropy maximization, is proposed. The suggested method has been applied to the synthetic aperture radar (SAR) image targets segmentation. Mathematical morphology works well in reducing the residual noise.展开更多
The form invariance and the Lie symmetry of the generalized Hamiltonian system are studied. Firstly, de?nitions and criteria of the form invariance and the Lie symmetry of the system are given. Next, the r...The form invariance and the Lie symmetry of the generalized Hamiltonian system are studied. Firstly, de?nitions and criteria of the form invariance and the Lie symmetry of the system are given. Next, the relation between the form invariance and the Lie symmetry is studied. Finally, two examples are given to illustrate the application of the results.展开更多
By means of continuation theorem of the coincidence degree theory, sufficient conditions are obtained for the existence of periodic solutions of a kind of third-order neutral delay functional differential equation wit...By means of continuation theorem of the coincidence degree theory, sufficient conditions are obtained for the existence of periodic solutions of a kind of third-order neutral delay functional differential equation with deviating arguments.展开更多
The traditional clutter map constant false alarm rate (CM-CFAR) detector is affected by interference and self-masking[1] which will cause the low probability of detection. To solve these problems, a novel algorithm na...The traditional clutter map constant false alarm rate (CM-CFAR) detector is affected by interference and self-masking[1] which will cause the low probability of detection. To solve these problems, a novel algorithm named clutter map CFAR with amplitude limiter (ALCM-CFAR) is proposed, in which the amplitude of the input signal is limited by a filter. The simulation results prove the effectiveness of ALCM-CFAR algorithm.展开更多
For heavy atoms or ions, such as, Rb and Cs et al., relativistic effect must be considered in the calculation. In this paper, the relativistic many-body perturbation theory is used to solve the Dirac equation. And the...For heavy atoms or ions, such as, Rb and Cs et al., relativistic effect must be considered in the calculation. In this paper, the relativistic many-body perturbation theory is used to solve the Dirac equation. And the zeroth-order hyperfine constants are evaluated with Dirac-Fock wave function. The finite basis sets of dirac equation are constructed by B-splines. With the finite basis sets the core polarization and the correlation diagrams are calculated. The hyperfine structure constants of the 5S1/2 and 6S<sub>1/2 states of 85Rb as well as the 6S1/2 and 7S<sub>1/2 states of 133Cs are evaluated.展开更多
A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) -...A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) - 900 mmol/L butanol - 10 mmol/L borate at pH 9.4 and a pressure-driven flow of 0.020 mL/min under 1.3 MPa was employed to manipulate the separation. Explosives HMX (1, 3, 5, 7-tetranitro-l, 3, 5, 7-tetrazacyclooctane) and TATB (triamino-trinitrobenzene), which were felted on fluorine rubber F2311 (polytrifluorochlorethylene and polyvinylidene fluoride 1/1 co-polymerization) and F2314 (polytrifluorochlorethylene and polyvinylidene fluoride 4/1 co-polymerization) were well separated with very good peak shapes.展开更多
The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission d...The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission delay of photogenerated carriers is given.From analysis on the frequency domain of the circuit model the device has two poles.One has the relationship with junction capacitance and the DPD’s load,the other with the depth and the doping concentration of the N-well in the DPD.Different depth of the N-well and different area of the DPDs with bandwidth were compared.The analysis results are important to design the high speed DPDs.展开更多
基金National Natural Science Foundation of China( 198710 0 5 )
文摘By means of an abstract continuation theorem, the existence criteria are established for the positive periodic solutions of a neutral functional differential equation d N d t=N(t)[a(t)-β(t)N(t)-b(t)N(t-σ(t))-c(t)N′(t-τ(t))].
文摘This paper summarizes several automatic text categorization algorithms in common use recently, analyzes and compares their advantages and disadvantages. It provides clues for making use of appropriate automatic classifying algorithms in different fields. Finally some evaluations and summaries of these algorithms are discussed, and directions to further research have been pointed out. Key words text categorization - naive bayes - KNN - SVM - neural network CLC number TP 391 Foundation item: Supported by the National Natural Science Foundation of China (70031010) and the Research Foundation of Beijing Institute of TechnologyBiography: SHI Yong-feng (1980-), male, Master candidate, research direction: web information mining.
文摘Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW_ 11O_ 39Ni(H_2O) 6-(SiNiW_ 11) and {SiW_ 11O_ 39Mn(H_2O) 6-}(SiMnW_ 11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-_3 and NO-_2 were comparatively studied.
文摘An open-loop fiber optic gyro (FOG) testing system is designed. The noise characteristic of open-loop fiber optic gyro signals is analyzed. The wavelet eliminating noise method is discussed and compared with other methods, such as smoothing and low-pass filter methods. Results indicate that the wavelet eliminating noise method can satisfy the measuring demand of the FOG weak output signal with noise disturbing. The wavelet analysis method can efficiently eliminate the noise and reserve the information of the signal. The eliminating noise effect of using different wavelet base functions is compared. The effectiveness of multiresolution wavelet analyses of eliminating noise is proved by experimental results.
文摘The explicit form of the evolution operator for the three-atom Tavis-Cummings model is given. The atoms can be entangled through their interaction with a thermal field. The degree of entanglement depends on the mean photon number of the thermal field and the initial state of the atoms.
文摘An improved heuristic ant-clustering algorithm(HAC)is presented in this paper.A device of ’memory bank’ is proposed,which can bring forth heuristic knowledge guiding ant to move in the bi-dimension grid space.The device lowers the randomness of ants’ moving and avoids the producing of"un-assigned data object".We have made some experiments on real data sets and synthetic data sets.The results demonstrate that HAC has superiority in misclassification error rate and runtime over the classical algorithm.
文摘Gas phase selective catalytic oxidation of toluene to benzatdehyde was studied on V_2O_5-Ag_2O/η-Al_2O_3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM, and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V+Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No. 4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzaldehyde were higher than those on the undoped catalyst. This was attributed to the disordered structure of V_2O_5 lattice of the K-doped catalyst and a better interracial contact between the particles.
文摘The compound of tetraacetyldibenzylhexaazaisowurtzitane (TADBIW) is an important precursor of synthesizing the high energetic dense compound of hexanitrohexaazaisowurtzitane (HNIW). We can obtain TADBIW by using hydrogenolysis of hexabenzylhexaazaisowurtzitane (HBIW). In the process of hydrogenolysis of HBIW, it will generate a variety of intermediates, one of them is the compound of triacetyltribenzylhexaazaisowurtzitane (TATBIW). We have synthesized the title compound and prepared its single crystal. In the paper, the crystal and molecular structure of TATBIW·0.5H2O is described. Its crystal belongs to the triclinic and space group P-1. The cell is comprised of two TATBIW and one water molecules. The success of synthesizing TATBIW can help us to research the mechanism of the reduction of HBIW and produce high yields of the end products.
文摘Safety incentive mechanism and corresponding motivation avenues are helpful and important for the scientific safety management in coal mine. With the help of modern systematic analysis method, the efficacy of safety incentive mechanisms is discussed in detail. The research shows that more effective avenue to reduce accident is to differently use motivation measures in practice.
文摘The control of single pneumatic muscle actuator is studied, as one basic partof research on the parallel-robot arthrosis actuated by pneumatic muscle actuators. Experimentsshow that a self-modified fuzzy-PID controller is obviously effective for its position servo and asimple PID controller is good for its force track.
文摘We have investigated the use of flash evaporation, headspace solid-phase microextraction (HS-SPME) and steam distillation (SD) as sample concentration and preparation techniques for the analysis of volatile constituents present in Houttuynia cordata Thunb. The samples were analyzed by gas chromatography (GC) and identified by mass spectrometry (MS). Comparison studies were performed. It was found that the results obtained between Headspace solid-phase microextraction HS-SPME and SD techniques were in good agreement. Seventy-nine compounds in Houttuynia cordata Thunb were identified by MS. In flash evaporation, thirty-nine compounds were identified. Discrimination in the response for many constituents studied was not observed, which can be clearly observed in SD and HS-SPME techniques. As a conclusion, HS-SPME is a powerful tool for determining the volatile constitutes present in the Houttuynia cordata.
文摘Entropy maximization thresholding is a simple, effective image segmentation method. The relation between the histogram entropy and the gray level of an image is analyzed. An approach, which speeds the computation of optimal threshold based on entropy maximization, is proposed. The suggested method has been applied to the synthetic aperture radar (SAR) image targets segmentation. Mathematical morphology works well in reducing the residual noise.
基金Project supported by the National Natural Science Foundation of China (Nos.19972010 and 10272021).
文摘The form invariance and the Lie symmetry of the generalized Hamiltonian system are studied. Firstly, de?nitions and criteria of the form invariance and the Lie symmetry of the system are given. Next, the relation between the form invariance and the Lie symmetry is studied. Finally, two examples are given to illustrate the application of the results.
文摘By means of continuation theorem of the coincidence degree theory, sufficient conditions are obtained for the existence of periodic solutions of a kind of third-order neutral delay functional differential equation with deviating arguments.
基金This project was supported by the National Natural Science Foundation of China (60232010).
文摘The traditional clutter map constant false alarm rate (CM-CFAR) detector is affected by interference and self-masking[1] which will cause the low probability of detection. To solve these problems, a novel algorithm named clutter map CFAR with amplitude limiter (ALCM-CFAR) is proposed, in which the amplitude of the input signal is limited by a filter. The simulation results prove the effectiveness of ALCM-CFAR algorithm.
文摘For heavy atoms or ions, such as, Rb and Cs et al., relativistic effect must be considered in the calculation. In this paper, the relativistic many-body perturbation theory is used to solve the Dirac equation. And the zeroth-order hyperfine constants are evaluated with Dirac-Fock wave function. The finite basis sets of dirac equation are constructed by B-splines. With the finite basis sets the core polarization and the correlation diagrams are calculated. The hyperfine structure constants of the 5S1/2 and 6S<sub>1/2 states of 85Rb as well as the 6S1/2 and 7S<sub>1/2 states of 133Cs are evaluated.
文摘A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) - 900 mmol/L butanol - 10 mmol/L borate at pH 9.4 and a pressure-driven flow of 0.020 mL/min under 1.3 MPa was employed to manipulate the separation. Explosives HMX (1, 3, 5, 7-tetranitro-l, 3, 5, 7-tetrazacyclooctane) and TATB (triamino-trinitrobenzene), which were felted on fluorine rubber F2311 (polytrifluorochlorethylene and polyvinylidene fluoride 1/1 co-polymerization) and F2314 (polytrifluorochlorethylene and polyvinylidene fluoride 4/1 co-polymerization) were well separated with very good peak shapes.
文摘The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission delay of photogenerated carriers is given.From analysis on the frequency domain of the circuit model the device has two poles.One has the relationship with junction capacitance and the DPD’s load,the other with the depth and the doping concentration of the N-well in the DPD.Different depth of the N-well and different area of the DPDs with bandwidth were compared.The analysis results are important to design the high speed DPDs.
