期刊文献+
共找到39篇文章
< 1 2 >
每页显示 20 50 100
对《铁道线路维修规则》中曲线维修隐含技术标准的分析与维修 被引量:1
1
作者 李永生 张连发 《铁道技术监督》 2006年第5期10-11,共2页
“正矢”和“正矢递变率”都是反映曲线圆度的主要数据,《铁道线路维修规则》(以下简称“维规”)以及有关文件中仅规定了铁道线路曲线维修的“正矢”控制标准,没有明确规定“正矢递变率”的控制标准,本文对此进行了分析,并提出了在快速... “正矢”和“正矢递变率”都是反映曲线圆度的主要数据,《铁道线路维修规则》(以下简称“维规”)以及有关文件中仅规定了铁道线路曲线维修的“正矢”控制标准,没有明确规定“正矢递变率”的控制标准,本文对此进行了分析,并提出了在快速条件下应加强控制曲线“正矢递变率”的理念及维修措施。 展开更多
关键词 《维规》 曲线 隐含标准
下载PDF
Study on Development Rule of Muscle Fiber in Different Duck Breeds 被引量:14
2
作者 廖菁 常国斌 +4 位作者 徐琪 张依裕 张海波 周琼 陈国宏 《Agricultural Science & Technology》 CAS 2009年第5期107-109,共3页
[Objective] The aim of this study was to investigate the development rule of muscle fiber in different duck breeds during various developmental stages. [Method] Cherry valley duck, Jinding duck, White muscory duck and... [Objective] The aim of this study was to investigate the development rule of muscle fiber in different duck breeds during various developmental stages. [Method] Cherry valley duck, Jinding duck, White muscory duck and Suma duck ( Cherry valley duck ♂ × Jinding duck ♀ ) were fed for 10 weeks to observe the ultrastructure of muscle fiber by electron microscope, and the myofibril diameter and sarcomere length were also determined. [Result] The myofibril diameter increased with ages. Sarcomere length and myofibril diameter did not change significantly with the increasing ages (P〉0.05). The myofibril diameter of White muscory duck and Jinding duck were thicker, while that of Cherry valley cluck and Suma duck were thinner. Moreover, the sarcomere length of Suma duck and White muscory duck were longer, while that of Cherry valley duck and Jinding duck were shorter. Thus, the basic characteristics of ultrastructure of muscle fiber were consistent in these duck breeds.[Conclusion] The results have an important meaning for duck breeding. 展开更多
关键词 DUCK Muscle fiber ULTRASTRUCTURE Development rule
下载PDF
Application of the Sediment Mathematical Modelling on Planned Project of Lingdingyang Bay 被引量:6
3
作者 李大鸣 李冰绯 张红萍 《Transactions of Tianjin University》 EI CAS 2002年第4期285-290,共6页
Based on the combined hydraulic calculation for the eastern network region at the Pearl River estuary and several outlets to the Lingdingyang Bay, the sediment calculation modelling was introduced in the establishment... Based on the combined hydraulic calculation for the eastern network region at the Pearl River estuary and several outlets to the Lingdingyang Bay, the sediment calculation modelling was introduced in the establishment of the sediment mathematical model for Lingdingyang Bay and the eastern region with one and two dimensional flow calculation. Model adjustment and verification were performed in conjunction with field data. The simulated results coincide well with measured data.In addition the model is applied to predict the shore-line planning scheme of Lingdingyang Bay.The theoretical criterion is provided for the shore line plan in the model.And a new mathematical simulated method is put out to research the planning engineering concerned with one-dimensional net rivers and two-dimensional estuary. 展开更多
关键词 sediment mathematical model one and two-dimensional flow calculation Lingdingyang bay shore-line plan
下载PDF
Meta-analysis of potentially confounding effect of class size on associations between object-oriented metrics and maintainability
4
作者 卢红敏 周毓明 徐宝文 《Journal of Southeast University(English Edition)》 EI CAS 2008年第3期281-283,共3页
This paper uses three size metrics,which are collectable during the design phase,to analyze the potentially confounding effect of class size on the associations between object-oriented(OO)metrics and maintainability... This paper uses three size metrics,which are collectable during the design phase,to analyze the potentially confounding effect of class size on the associations between object-oriented(OO)metrics and maintainability.To draw as many general conclusions as possible,the confounding effect of class size is analyzed on 127 C++ systems and 113 Java systems.For each OO metric,the indirect effect that represents the distortion of the association caused by class size and its variance for individual systems is first computed.Then,a statistical meta-analysis technique is used to compute the average indirect effect over all the systems and to determine if it is significantly different from zero.The experimental results show that the confounding effects of class size on the associations between OO metrics and maintainability generally exist,regardless of whatever size metric is used.Therefore,empirical studies validating OO metrics on maintainability should consider class size as a confounding variable. 展开更多
关键词 OBJECT-ORIENTED metrics VALIDATION class size CONFOUNDING MAINTAINABILITY
下载PDF
Fractal features of size distribution of Chinese intercity bus hubs
5
作者 姚志刚 周伟 《Journal of Southeast University(English Edition)》 EI CAS 2007年第4期626-629,共4页
Size distribution characteristics of intercity bus hubs in China from 1997 to 2(104 were analyzed regarding highway passenger volume as a size index of intercity bus hubs. Yearly fractal dimensions of intercity bus h... Size distribution characteristics of intercity bus hubs in China from 1997 to 2(104 were analyzed regarding highway passenger volume as a size index of intercity bus hubs. Yearly fractal dimensions of intercity bus hub sizes were exactly calculated by a novel model. Fractal dimensions of the 200 biggest intercity bus hubs from 2000 to 2004 were 1. 486 2 to 1. 511 8, and that is consistent with fractal dimensions of Chinese urban system sizes. It showed that the size distribution of intercity bus hubs had fractal structure. Fractal dimensions from 1997 to 2004 indicated that intercity bus hub size distribution grew from bi-fractal to single fractal. It is concluded that the intercity bus hub system is in evolutionary progress, and the Central Government should support large intercity bus hubs more to optimize system structure. 展开更多
关键词 intercity bus hub FRACTAL size distribution fractal dimension
下载PDF
Analysis on the Production Advantages of USA Pima Extra Long Staple Cotton
6
作者 田立文 徐志武 +7 位作者 郑子漂 宁新民 崔建平 朱斌 徐海江 郭仁松 林涛 刘志清 《Agricultural Science & Technology》 CAS 2017年第5期892-903,共12页
This paper defines the following advantages of ELS (Extra Long Staple) also known as Pima cotton planted in the United States: first, the only variety which is concentrated in the planting area with good soil moist... This paper defines the following advantages of ELS (Extra Long Staple) also known as Pima cotton planted in the United States: first, the only variety which is concentrated in the planting area with good soil moisture and fertilizer retention performances and abundant light and heat resources; second; advanced and practi- cal material equipment and technology; third; high yield and good quality, significant planting scale benefit; fourth, feasible and reliable modernized intensive farm man- agement mode with large-scale agricultural machinery operation; fifth, high-efficient social services and policy support system, as well as reasonable planting layout, good brand influence, synchronization of high yield and good quality with large-scale benefits. Although the production capability of Pima cotton in the United States is considered to be the largest and most powerful country in the world, compared with the ELS production in China, both have their own advantages and characteristics. Therefore, it is suggested that by using the ELS production experience ol the Unit- ed Stages for reference, China should make use of the modern breeding technJques to accelerate the modification of synthetic genetic features of ELS variety, try its best to breed the ELS variety which is suitable for mechanical plucking as soon as possible, actively develop new technology to simplify the whole cost saving cultiva- tion, reform ELS production organization, vigorously develop the social service sys- tem, and adjust and optimize the ELS industry support policies, so as to fundamen- tally improve the competitiveness of China's ELS in international market. 展开更多
关键词 ELS (Extra Long Staple) or Pima cotton Natural Ecology Planting lay-out and scale Fiber quality Material equipment
下载PDF
GRAPH GRAMMAR METHOD FOR 3-D CORNER DETECTION
7
作者 关卓威 张晔 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2012年第3期289-293,共5页
Most of local feature descriptors assume that the scene is planar. In the real scene, the captured images come from the 3-D world. 3-D corner as a novel invariant feature is important for the image matching and the ob... Most of local feature descriptors assume that the scene is planar. In the real scene, the captured images come from the 3-D world. 3-D corner as a novel invariant feature is important for the image matching and the object detection, while automatically discriminating 3-D corners from ordinary corners is difficult. A novel method for 3-D corner detection is proposed based on the image graph grammar, and it can detect the 3-D features of corners to some extent. Experimental results show that the method is valid and the 3-D corner is useful for image matching. 展开更多
关键词 graph grammar 3-D corner detection production rule
下载PDF
Radial Based Probabilistic Roadmap Motion Planning Method in Sparse Environment
8
作者 高春晓 刘玉树 郑军 《Journal of Beijing Institute of Technology》 EI CAS 2002年第1期89-92,共4页
A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, ... A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, it uses straight lines as long as possible to construct a path graph, so the final path obtained from the graph is relatively shorter and straighter. Experimental results show the efficiency of the algorithm in finding shorter paths in sparse environment. 展开更多
关键词 path planning probabilistic roadmap method collision avoidance ROBOTICS virtual reality
下载PDF
Dynamical chiral symmetry breaking in QED_3
9
作者 周雨青 《Journal of Southeast University(English Edition)》 EI CAS 2014年第4期544-549,共6页
In order to examine how a propagator behaves in non-perturbative theories and how its behavior is influenced by the choice of a covariant gauge a truncated Dyson-Schwinger equation is used to numerically investigate t... In order to examine how a propagator behaves in non-perturbative theories and how its behavior is influenced by the choice of a covariant gauge a truncated Dyson-Schwinger equation is used to numerically investigate the properties of fermions and bosons in 3D quantum electrodynamics QED and a series of self-consistent solutions for the fermion propagator in the Nambu and Wigner phases are obtained. These numerical solutions show that the propagator behaves very differently in the Landau gauge domain and in the infrared energy region outside it.By using the propagators in the Nambu and Wigner phases under various gauges it is further investigated how the fermion equivalent pressure difference and fermion condensation change with the gauge parameters.These results indicate that the phase transition described by the CJT equivalent potential and the chiral phase transition described by the chiral condensation are not completely identical. 展开更多
关键词 PROPAGATOR covariant gauge 3D quantumelectrodynamics QED equivalent pressure difference fermion condensation chiral phase transition
下载PDF
New Multiple Soliton-like and Periodic Solutions for (2+l)-Dimensional Canonical Generalized KP Equation with Variable Coefficients 被引量:3
10
作者 ZHANG Li-Hua LIU Xi-Qiang BAI Cheng-Lin 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第5X期793-798,共6页
In this paper, the generalized ranch function method is extended to (2+1)-dimensianal canonical generalized KP (CGKP) equation with variable coetfficients. Taking advantage of the Riccati equation, many explicit ... In this paper, the generalized ranch function method is extended to (2+1)-dimensianal canonical generalized KP (CGKP) equation with variable coetfficients. Taking advantage of the Riccati equation, many explicit exact solutions, which contain multiple soliton-like and periodic solutions, are obtained for the (2+1)-dimensional OGKP equation with variable coetffcients. 展开更多
关键词 (2+1)-dimensional canonical generalized (CGKP) equation with variable coefficients tanh function method Riccati equation soliton-like and periodic solutions
下载PDF
Dimension-down iterative algorithm for the mixed transportation network design problem
11
作者 陈群 姚加林 《Journal of Southeast University(English Edition)》 EI CAS 2012年第2期236-239,共4页
An optimal dimension-down iterative algorithm (DDIA) is proposed for solving a mixed (continuous/ discrete) transportation network design problem (MNDP), which is generally expressed as a mathematical programmin... An optimal dimension-down iterative algorithm (DDIA) is proposed for solving a mixed (continuous/ discrete) transportation network design problem (MNDP), which is generally expressed as a mathematical programming with equilibrium constraints (MPEC). The upper level of the MNDP aims to optimize the network performance via both the expansion of existing links and the addition of new candidate links, whereas the lower level is a traditional Wardrop user equilibrium (UE) model. The idea of the proposed DDIA is to reduce the dimensions of the problem. A group of variables (discrete/continuous) are fixed to altemately optimize another group of variables (continuous/discrete). Some continuous network design problems (CNDPs) and discrete network design problems (DNDPs) are solved repeatedly until the optimal solution is obtained. A numerical example is given to demonstrate the efficiency of the proposed algorithm. 展开更多
关键词 mixed network design problem (MNDP) dimension-down iterative algorithm (DDIA) mathematical programming with equilibrium constraint (MPEC)
下载PDF
Temporal Floorplanning Using Solution Space Smoothing Based on 3D-BSSG Structure
12
作者 郑舒一 董社勤 洪先龙 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第10期1916-1924,共9页
We develop a 3D bounded slice-surface grid (3D-BSSG) structure for representation and introduce the solution space smoothing technique to search for the optimal solution. Experiment results demonstrate that a 3D-BSS... We develop a 3D bounded slice-surface grid (3D-BSSG) structure for representation and introduce the solution space smoothing technique to search for the optimal solution. Experiment results demonstrate that a 3D-BSSG structure based algorithm is very effective and efficient. 展开更多
关键词 temporal floorplanning~ FPGA 3D-BSSG solution space smoothing
下载PDF
Experimental study on energy storage and dissipation characteristics of granite under two-dimensional compression with constant confining pressure 被引量:17
13
作者 SU You-qiang GONG Feng-qiang +1 位作者 LUO Song LIU Zhi-xiang 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第3期848-865,共18页
To study the energy storage and dissipation characteristics of deep rock under two-dimensional compression with constant confining pressure,the single cyclic loading-unloading two-dimensional compression tests were pe... To study the energy storage and dissipation characteristics of deep rock under two-dimensional compression with constant confining pressure,the single cyclic loading-unloading two-dimensional compression tests were performed on granite specimens with two height-to-width(H/W)ratios under five confining pressures.Three energy density parameters(input energy density,elastic energy density and dissipated energy density)in the axial and lateral directions of granite specimens under different confining pressures were calculated using the area integral method.The experimental results show that,for the specimens with a specific H/W ratio,these three energy density parameters in the axial and lateral directions increase nonlinearly with the confining pressure as quadratic polynomial functions.Under constant confining pressure compression,the linear energy storage law of granite specimens in the axial and lateral directions was founded.Using the linear energy storage law in different directions,the elastic energy density in various directions(axial elastic energy density,lateral elastic energy density and total elastic energy density)of granite under any specific confining pressures can be calculated.When the H/W ratio varies from 1:1 to 2:1,the lateral compression energy storage coefficient increases and the corresponding axial compression energy storage coefficient decreases,while the total compression energy storage coefficient is almost independent of the H/W ratio. 展开更多
关键词 rock mechanics two-dimensional compression linear energy storage law single cyclic loading-unloading height-to-width ratio
下载PDF
Use of Wood Fibre Compost for the Cultivation of Trichoderma sp, (Isolate Td22)
14
作者 Yan Ramona Martin A. Line 《Journal of Life Sciences》 2013年第7期695-699,共5页
The main objective of this research was to investigate the ability of a Trichoderma sp. (Td22), inhibitory to Sclerotinia minor Jagger, to grow and survive in mature wood fibre waste (WFW) compost of paper mill or... The main objective of this research was to investigate the ability of a Trichoderma sp. (Td22), inhibitory to Sclerotinia minor Jagger, to grow and survive in mature wood fibre waste (WFW) compost of paper mill origin following nutrient amendment. The growth and survival of the fungus in the WFW compost was assessed by serial dilution plate count method followed by confirmation of the fungal identity using pectic enzyme analysis as described in Cruickshank and Pitt [1]. It was found in this study that the population densities of TdE2 achieved under non-sterile conditions in the WFW compost following nutrient amendment was approximately in the range of 7.0 lOgl0 CFU/g dw - 8.5 log10 CFU/g dw after 28 days, depending on pre-treatment. The efficacy of this WFW compost-grown TdE2 for protection of lettuce from attack by S. minor was also demonstrated in glasshouse trials. This study indicates that cellulosic paper mill waste compost could provide an abundant low-cost growth medium for the large-scale cultivation of fungal antagonists, improving prospects for cost-competitiveness with chemical treatments. 展开更多
关键词 COMPOST biological control Trichoderma sp. Sclerotinia minor.
下载PDF
Cultural study on trade disputes between China and the West
15
作者 陈肖 《Sino-US English Teaching》 2008年第7期57-60,共4页
In recent years, China's international trade has made great actuevements, However, when carefully reviewing its performance in the international market, we have to admit a fact that "Chinese businessmen" and "Made... In recent years, China's international trade has made great actuevements, However, when carefully reviewing its performance in the international market, we have to admit a fact that "Chinese businessmen" and "Made in China" are encountering great challenges, even aversion in many foreign markets. The so-called "Yellow peril theory" and "China threat theory" have caught on once again. Faced with such frequent trade conflicts, we fall into contemplation. Why did trade conflicts so frequently happen? Do these conflicts merely remain at the commercial level? Or, are there any deep-seated conflicts leading to trade conflicts? What are the root causes of these conflicts? How to overcome and avoid these conflicts in the future? With these questions, this paper is designed to inquire into the root cause of trade conflicts and the constructive suggestions to settle trade conflicts from a cultural perspective. 展开更多
关键词 trade conflict cultural conflict CONDUCT way of thinking cultural value
下载PDF
Modeling and Assessing a New Warship Maintenance System 被引量:1
16
作者 赵金超 齐欢 张勇明 《Journal of Marine Science and Application》 2010年第1期69-74,共6页
The authors developed a prototype of a warship maintenance system. The process started by defining the maintenance requirements of warship equipment. Next, a planning scheme was development for a maintenance network. ... The authors developed a prototype of a warship maintenance system. The process started by defining the maintenance requirements of warship equipment. Next, a planning scheme was development for a maintenance network. An optimization target for the plan and indexes for assessment were established. Based on the above work, a simulation model was proposed with two layers: a base and a workshop. Dispatching rules were then formulated for the simulation. Experimental results proved the validity of the model and the dispatching algorithm. It was found that the model can solve the capacity evaluation problem for maintenance systems and provides a scientific basis for decision-maker to make decisions regarding equipment maintenance. 展开更多
关键词 capability assessment planning optimization heuristic regulation warship maintenance system
下载PDF
Interactive Model Used in Maintenance Planning of Facades Based on Virtual Reality Technology
17
作者 Alcinia Zita Sampaio Augusto M. Gomes Ana Rita Gomes 《Journal of Civil Engineering and Architecture》 2012年第10期1292-1309,共18页
A virtual reality model was created in order to help in the maintenance of exterior closures and interior finishes of walls in a building. It allows the visual and interactive transmission of information related to th... A virtual reality model was created in order to help in the maintenance of exterior closures and interior finishes of walls in a building. It allows the visual and interactive transmission of information related to the physical behavior of the elements, defined as a function of the time variable. To this end, the basic knowledge of material most often used in walls, anomaly surveillance, techniques of rehabilitation, and inspection planning were studied. This information was included in a database that supports the periodic inspection needed in a program of preventive maintenance. The results are obtained interactively and visualized in the virtual environment itself. This work brings an innovative contribution to the field of maintenance supported by emergent technology. 展开更多
关键词 Construction maintenance cooperative visualization virtual reality decision-making.
下载PDF
Dialectical thinking in engineering management
18
作者 Yang Shanlin Huang Zhibin Ren Xueping 《Engineering Sciences》 EI 2012年第5期76-89,共14页
Modem engineering management activities have all become more complex, being far beyond the economic and technological areas, due to their growing grand scales, increasingly complex structures and integrated systems. T... Modem engineering management activities have all become more complex, being far beyond the economic and technological areas, due to their growing grand scales, increasingly complex structures and integrated systems. Therefore, we need focus our attention on engineering management activities by resorting to dialectical thinking and take full account of them based on the height of the new era. This paper described and analyzed engineering management activities from the following 5 aspects : the cyclic promotion between engineering management theory and engineering management practice, the in-depth integration of engineering management concepts with engineering management methods, the coordinated harmonization of engineering management system with engineering management details, the mutual promotion between engineering management standardization and engineering management innovation, the common enhancement between engineering management team and engineering management system. 展开更多
关键词 ENGINEERING engineering management dialectical thinking
下载PDF
RESEARCH ON SOME THEORETICAL PROBLEMS OF MAP DATA HANDLING USING FRACTAL APPROACH
19
作者 WANG Qiao 《Geo-Spatial Information Science》 2000年第1期34-38,共5页
Some theoretical problems of fractal geographical map data handling are dis- cussed and some new methods about fractal dimension introducing, developing, comparing and estimating are proposed in this paper.
关键词 fractals fractal dimension SELF-SIMILARITY scale interval
下载PDF
Contribution of Lake Victoria Small-scale Fisheries to Poverty Alleviation: A Case Study of Tanzania Small-scale Fisheries
20
作者 Odass Bilame 《Journal of Agricultural Science and Technology(B)》 2012年第12期1268-1278,共11页
This paper has attempted to show the contribution of Lake Victoria small-scale fisheries to poverty alleviation. Two districts in Mwanza region in the Lake Victoria Zone were identified for a field research. The two d... This paper has attempted to show the contribution of Lake Victoria small-scale fisheries to poverty alleviation. Two districts in Mwanza region in the Lake Victoria Zone were identified for a field research. The two districts are Sengerema and Ilemela. The results show that during high catch season both fishers and fishing gear owners generated high incomes, although gear owners were relatively far better than fishers. This was true for both Sardines and Nile perch fisheries. For instance, during high catch season, 39 sardine fishers each generated monthly income that ranged between $300 and $1,100, and 18 further fishers each generated income that was below $300. However, during low catch season, the incomes generated were very low for both fishers and gear owners to an extent of not even recovering the variable costs. The scenario was different with Nile perch fishers, out of 53 fishers that were sampled, 44 fishers each generated net monthly income that was below $400 during high catch season and during low catch season, 46 out of 53 fishers each generated net monthly income that was below $200. Fishers were the hardest hit during low catch season. 展开更多
关键词 FISHERIES small-scale fisheries fishers and gear owners poverty alleviation.
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部