Let n be a positive integer satisfying n >1; ω(n) denotes the number of distinct prime factors of n ; σ(n) denotes the sum of the positive divisors of n . If σ(n)=2n then n is said to be a perfect number and if ...Let n be a positive integer satisfying n >1; ω(n) denotes the number of distinct prime factors of n ; σ(n) denotes the sum of the positive divisors of n . If σ(n)=2n then n is said to be a perfect number and if σ(n)=kn(k≥3) then n is said to be a multiply perfect number. In this paper according to Euler theorem and Fermat theorem, we discuss the result of σ(n)=ω(n)n and prove that only n=2 3·3·5, 2 5·3·7, 2 5·3 3·5·7 satisfies σ(n)= ω(n) n(ω(n)≥3). ...展开更多
A new 18-lump kinetic model for naphtha catalytic reforming reactions is discussed. By developing this model as a user module, a whole industrial continuous catalytic reforming process is simulated on Aspen plus plat-...A new 18-lump kinetic model for naphtha catalytic reforming reactions is discussed. By developing this model as a user module, a whole industrial continuous catalytic reforming process is simulated on Aspen plus plat-form. The technique utilizes the strong databases, complete sets of modules, and flexible simulation tools of the Aspen plus system and retains the characteristics of the proposed kinetic model. The calculated results are in fair agreement with the actual operating data. Based on the model of the whole reforming process, the process is opti-mized and the optimization results are tested in the actual industrial unit for about two months. The test shows that the process profit increases about 1000yuan·h-1 averagely, which is close to the calculated result.展开更多
The conception of multilevel security (MLS) is commonly used in the study of data model for secure database. But there are some limitations in the basic MLS model, such as inference channels. The availability and data...The conception of multilevel security (MLS) is commonly used in the study of data model for secure database. But there are some limitations in the basic MLS model, such as inference channels. The availability and data integrity of the system are seriously constrained by it′s 'No Read Up, No Write Down' property in the basic MLS model. In order to eliminate the covert channels, the polyinstantiation and the cover story are used in the new data model. The read and write rules have been redefined for improving the agility and usability of the system based on the MLS model. All the methods in the improved data model make the system more secure, agile and usable.展开更多
This paper gives a new definition of the filled function for nonlinear integer programming problem. A filled function satisfying our definition is presented. This function contains only one parameter. The properties o...This paper gives a new definition of the filled function for nonlinear integer programming problem. A filled function satisfying our definition is presented. This function contains only one parameter. The properties of the proposed filled function and the method using this filled function to solve nonlinear integer programming problem are also discussed. Numerical results indicate the efficiency and reliability of the proposed filled function algorithm.展开更多
In order to reduce the computation in the part of motion search and transform in H.26L encoder, an all-zero macroblock decision method based on integer transform and motion search is proposed in this paper. According ...In order to reduce the computation in the part of motion search and transform in H.26L encoder, an all-zero macroblock decision method based on integer transform and motion search is proposed in this paper. According to the characteristics of integer transform and motion search in H.26L, all-zero macroblock decision is made in inter frame coding by comparing Sum of the Absolute Differences(SAD) with a value related with Quantization Parameter(QP)before integer transform. It avoids a large amount of computation in motion search, transform and quantization. This technology highly improves the efficiency of real time H.26L encoder by skipping all-zero macroblock before integer transform and shortening the code stream at the same time.展开更多
Panorama field geological image is an important form of displaying field geology information with high resolution.Taking an example for Xingcheng,the authors studied the use of panorama field geological images based o...Panorama field geological image is an important form of displaying field geology information with high resolution.Taking an example for Xingcheng,the authors studied the use of panorama field geological images based on the Flex for rich client display technology,application of Google maps API for Flash,and discussed construction method for field geological panoramic information system which created the rich client Internet application program.The results indicate that using Google maps API to mark position and route of panoramic image collection point can be fully integrated field geological information and map information.It can provide visual field geological information for users.This program is characterized by quick execution speed,strong interaction and rich function,which promotes the users'experience effectively.展开更多
Objective To evaluate the monitoring and diagnostic potential of MR in fetal lung development using lung signal intensity changes in the fetus. Methods The lung-to-liver intensity ratio was calculated by means of regi...Objective To evaluate the monitoring and diagnostic potential of MR in fetal lung development using lung signal intensity changes in the fetus. Methods The lung-to-liver intensity ratio was calculated by means of region-of-interest analysis in all 35 fetuses including 7 bilateral urinary anomalies, 9 unilateral urinary anomalies, 5 pulmonary anomalies, and 14 others. Results All fetuses with urinary anomalies and pulmonary anomalies showed low ratio of lung-to-liver signal intensity. Conclusion Low ratio of lung-to-liver signal intensity on MR imaging indicates pulmonary hypoplasia after 22 weeks’ gestation.展开更多
The method of integrated data processing for GPS and INS(inertial navigation system) field test over the Rocky Mountains using the adaptive Kalman filtering technique is presented. On the basis of the known GPS output...The method of integrated data processing for GPS and INS(inertial navigation system) field test over the Rocky Mountains using the adaptive Kalman filtering technique is presented. On the basis of the known GPS outputs and the offset of GPS and INS, state equations and observations are designed to perform the calculation and improve the navigation accuracy. An example shows that with the method the reliable navigation parameters have been obtained.展开更多
Outgrower Schemes have been implemented in different parts of the world to provide wood to forest and other companies and as income alternatives for farmers in rural areas. They have been considered by some researcher...Outgrower Schemes have been implemented in different parts of the world to provide wood to forest and other companies and as income alternatives for farmers in rural areas. They have been considered by some researchers and practitioners as important advances in the area of planted forest and promoted by governments and forest companies in partnership with rural farmers and communities. Considering the importance of subsistence crops and forest products to smallholders and consumers and the economic viability of agroforestry, attention is given in this paper to Outgrower Schemes that combine tree planting with agroforestry, to contribute to food security and environment preservation in developing countries. The issue of Outgrower Schemes through integrated crops-tree systems was raised in a previous study of Outgrower Schemes in Brazil, commissioned by the FAO1. This paper examines, based on the research done for that study, the views and perspectives of the companies＇ personnel, the tree growers that participate in the programs studied, and other stakeholders＇ related institutions involved in such schemes with regard to the promotion of Outgrower Schemes through integrated crops-tree systems, linking them with agroforestry, which is a way those Outgrower Schemes can contribute to food security and environment preservation goals.展开更多
By using the output inductors and body capacitances without adding any component compared with hard switching synchronous rectifier,the topology of a soft switched synchronous rectifier with phase-shifted full bridge ...By using the output inductors and body capacitances without adding any component compared with hard switching synchronous rectifier,the topology of a soft switched synchronous rectifier with phase-shifted full bridge zero voltage switching DC/DC converter is proposed. The converter efficiency is maximized due to soft switching of the full bridge MOSFETs and the synchronous MOSFETs, and also the low conduction loss of synchronous MOSFET. The operation principles of the circuit are analyzed in detail and the small-signal model is derived, also the converter dynamic characteristics are analyzed. Frequency responses of transfer functions under different values of transformer primary leakage inductance are discussed. The experimental results were obtained from a 400 V input and 100 A/12 V output DC/DC converter operating at 100 kHz. The results show that the converter efficiency is 2% higher in rated power than traditional diode rectifier.展开更多
This article analyzes the problem of computer network security, and design scheme of the network security system. The scheme uses advanced network security technologies, includes a complete set of physical isolation, ...This article analyzes the problem of computer network security, and design scheme of the network security system. The scheme uses advanced network security technologies, includes a complete set of physical isolation, desktop system security, virus protection, identity authentication, access control, information encryption, message integrity check, non-repudiation, security audit, intrusion detection, vulnerability scanning, electromagnetic leakage emission protection, security management and other security technology and management measures, the purpose is to establish a complete, multi-level three-dimensional, network security defense system.展开更多
An adaptive output feedback control was proposed to deal with a class of nonholonomic systems in chained form with strong nonlinear disturbances and drift terms. The objective was to design adaptive nonlinear output f...An adaptive output feedback control was proposed to deal with a class of nonholonomic systems in chained form with strong nonlinear disturbances and drift terms. The objective was to design adaptive nonlinear output feedback laws such that the closed-loop systems were globally asymptotically stable, while the estimated parameters remained bounded. The proposed systematic strategy combined input-state-scaling with backstepping technique. The adaptive output feedback controller was designed for a general case of uncertain chained system. Furthermore, one special case was considered. Simulation results demonstrate the effectiveness of the proposed controllers.展开更多
文摘Let n be a positive integer satisfying n >1; ω(n) denotes the number of distinct prime factors of n ; σ(n) denotes the sum of the positive divisors of n . If σ(n)=2n then n is said to be a perfect number and if σ(n)=kn(k≥3) then n is said to be a multiply perfect number. In this paper according to Euler theorem and Fermat theorem, we discuss the result of σ(n)=ω(n)n and prove that only n=2 3·3·5, 2 5·3·7, 2 5·3 3·5·7 satisfies σ(n)= ω(n) n(ω(n)≥3). ...
基金Supported by the National Natural Science Foundation of China (No.60421002).
文摘A new 18-lump kinetic model for naphtha catalytic reforming reactions is discussed. By developing this model as a user module, a whole industrial continuous catalytic reforming process is simulated on Aspen plus plat-form. The technique utilizes the strong databases, complete sets of modules, and flexible simulation tools of the Aspen plus system and retains the characteristics of the proposed kinetic model. The calculated results are in fair agreement with the actual operating data. Based on the model of the whole reforming process, the process is opti-mized and the optimization results are tested in the actual industrial unit for about two months. The test shows that the process profit increases about 1000yuan·h-1 averagely, which is close to the calculated result.
文摘The conception of multilevel security (MLS) is commonly used in the study of data model for secure database. But there are some limitations in the basic MLS model, such as inference channels. The availability and data integrity of the system are seriously constrained by it′s 'No Read Up, No Write Down' property in the basic MLS model. In order to eliminate the covert channels, the polyinstantiation and the cover story are used in the new data model. The read and write rules have been redefined for improving the agility and usability of the system based on the MLS model. All the methods in the improved data model make the system more secure, agile and usable.
文摘This paper gives a new definition of the filled function for nonlinear integer programming problem. A filled function satisfying our definition is presented. This function contains only one parameter. The properties of the proposed filled function and the method using this filled function to solve nonlinear integer programming problem are also discussed. Numerical results indicate the efficiency and reliability of the proposed filled function algorithm.
文摘In order to reduce the computation in the part of motion search and transform in H.26L encoder, an all-zero macroblock decision method based on integer transform and motion search is proposed in this paper. According to the characteristics of integer transform and motion search in H.26L, all-zero macroblock decision is made in inter frame coding by comparing Sum of the Absolute Differences(SAD) with a value related with Quantization Parameter(QP)before integer transform. It avoids a large amount of computation in motion search, transform and quantization. This technology highly improves the efficiency of real time H.26L encoder by skipping all-zero macroblock before integer transform and shortening the code stream at the same time.
文摘Panorama field geological image is an important form of displaying field geology information with high resolution.Taking an example for Xingcheng,the authors studied the use of panorama field geological images based on the Flex for rich client display technology,application of Google maps API for Flash,and discussed construction method for field geological panoramic information system which created the rich client Internet application program.The results indicate that using Google maps API to mark position and route of panoramic image collection point can be fully integrated field geological information and map information.It can provide visual field geological information for users.This program is characterized by quick execution speed,strong interaction and rich function,which promotes the users'experience effectively.
文摘Objective To evaluate the monitoring and diagnostic potential of MR in fetal lung development using lung signal intensity changes in the fetus. Methods The lung-to-liver intensity ratio was calculated by means of region-of-interest analysis in all 35 fetuses including 7 bilateral urinary anomalies, 9 unilateral urinary anomalies, 5 pulmonary anomalies, and 14 others. Results All fetuses with urinary anomalies and pulmonary anomalies showed low ratio of lung-to-liver signal intensity. Conclusion Low ratio of lung-to-liver signal intensity on MR imaging indicates pulmonary hypoplasia after 22 weeks’ gestation.
基金Supported by the Scientific Research Foundation for ROCS,SEMJiangxi Education Bureau Project(No.200525) .
文摘The method of integrated data processing for GPS and INS(inertial navigation system) field test over the Rocky Mountains using the adaptive Kalman filtering technique is presented. On the basis of the known GPS outputs and the offset of GPS and INS, state equations and observations are designed to perform the calculation and improve the navigation accuracy. An example shows that with the method the reliable navigation parameters have been obtained.
文摘Outgrower Schemes have been implemented in different parts of the world to provide wood to forest and other companies and as income alternatives for farmers in rural areas. They have been considered by some researchers and practitioners as important advances in the area of planted forest and promoted by governments and forest companies in partnership with rural farmers and communities. Considering the importance of subsistence crops and forest products to smallholders and consumers and the economic viability of agroforestry, attention is given in this paper to Outgrower Schemes that combine tree planting with agroforestry, to contribute to food security and environment preservation in developing countries. The issue of Outgrower Schemes through integrated crops-tree systems was raised in a previous study of Outgrower Schemes in Brazil, commissioned by the FAO1. This paper examines, based on the research done for that study, the views and perspectives of the companies＇ personnel, the tree growers that participate in the programs studied, and other stakeholders＇ related institutions involved in such schemes with regard to the promotion of Outgrower Schemes through integrated crops-tree systems, linking them with agroforestry, which is a way those Outgrower Schemes can contribute to food security and environment preservation goals.
文摘By using the output inductors and body capacitances without adding any component compared with hard switching synchronous rectifier,the topology of a soft switched synchronous rectifier with phase-shifted full bridge zero voltage switching DC/DC converter is proposed. The converter efficiency is maximized due to soft switching of the full bridge MOSFETs and the synchronous MOSFETs, and also the low conduction loss of synchronous MOSFET. The operation principles of the circuit are analyzed in detail and the small-signal model is derived, also the converter dynamic characteristics are analyzed. Frequency responses of transfer functions under different values of transformer primary leakage inductance are discussed. The experimental results were obtained from a 400 V input and 100 A/12 V output DC/DC converter operating at 100 kHz. The results show that the converter efficiency is 2% higher in rated power than traditional diode rectifier.
文摘This article analyzes the problem of computer network security, and design scheme of the network security system. The scheme uses advanced network security technologies, includes a complete set of physical isolation, desktop system security, virus protection, identity authentication, access control, information encryption, message integrity check, non-repudiation, security audit, intrusion detection, vulnerability scanning, electromagnetic leakage emission protection, security management and other security technology and management measures, the purpose is to establish a complete, multi-level three-dimensional, network security defense system.
基金Project(60704005) supported by the National Natural Science Foundation of China Project(07ZR14119) supported by Natural Science Foundation of Shanghai Science and Technology Commission Project(2009AA04Z213) supported by the National High-Tech Research and Development Program of China
文摘An adaptive output feedback control was proposed to deal with a class of nonholonomic systems in chained form with strong nonlinear disturbances and drift terms. The objective was to design adaptive nonlinear output feedback laws such that the closed-loop systems were globally asymptotically stable, while the estimated parameters remained bounded. The proposed systematic strategy combined input-state-scaling with backstepping technique. The adaptive output feedback controller was designed for a general case of uncertain chained system. Furthermore, one special case was considered. Simulation results demonstrate the effectiveness of the proposed controllers.
