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1.
This paper presents a new approximate method for computation of an equivalent diameter of step beam. The comparison between the approximate and exact results shows that the method of this paper is suitable.  相似文献   

2.
Many papers often use new metric on space,which isequivalent to old metric.This paper gives two methods to generatenew topological equivalent metric,and it is valuable to theories andapplications.  相似文献   

3.
In this paper ,the innovational research is based on widely absorbing patents and applied technique at home and abroad and pointing out the disadvantage and ameliorative method of heat/low meter. According to the principle of therrnopile, and the three - dimensional loop wire laying is substituted by new - style plane wire laying. The construction and manufacture of new - style heat flow meter is declared. The new method will facilitate the manufacture and reduce the cost and the high precision feeler is assured by consistent line length, capacitance, resistance and inductance and the cost of determination in present demarcation will be cheaper than traditional feeler of heat flow meter. The high precision energy saving detection instrument is provided for the field of heat energy.  相似文献   

4.
It is necessary to simplify the capacity spectrum into bilinear form so as to get characteristic point of hysteretic bone curve(especially the yield point and the yielded stiffness),ductility and equivalent damping of the structure.Three general methods of calculating yield point and yielded stiffness of equivalent SDOF are introduced and the yield point and the yielded stiffness of three frame structures are compared using above given methods in this paper.The hysteretic bone curves of equivalent SDOF are decided by the equivalent yield force and displacement,the maximum plastic displacements of equivalent SDOF under rare earthquake are calculated,and it is compared with the maximum plastic displacements of member structures using nonlinear dynamic analysis.Finally,the advice of simplifying capacity spectrum is advanced.  相似文献   

5.
Through the analysis of the equivalent resistance method, a limitation of the equivalent capacity method was presented. When the direction of power at the feeder source end was changing, the equivalent capacity method for handling small generations would produce a large power loss calculation error. An improved calculation method, one not based on a single equivalent resistance, was proposed. In this method, one day was divided into several periods (such as 24 h), so that the direction of power at the feeder source end for each period does not vary. The equivalent resistance and energy loss in each period were calculated. The sum of all energy losses provided the daily energy loss total. Numerical examples were used to verify the improved method.  相似文献   

6.
With interconnecting and developing of power system, the problem of power flow computation on dispersed data resource need to be solved. A new distributed computation method of power flow based on Ward equivalent is presented. According to master-slaver splitting principle, multi-area interconnected power system is divided into master-slaver areas. Boundary buses in different areas are defined as different bus-types. Neighborhood areas are equivalent by Ward equivalent principle, and the equivalent injection power and equivalent impedance are worked out. Power flows from master area to slaver areas are solved by Newton method, and the equivalent injection power and equivalent impedance on the boundary are modified by their solutions. The process above repeats until to convergence. The proposed distributed power flow method takes full advantage of the information of power, voltage, network configuration in neighborhood areas, so it is better on convergence and quality of solution. The proposed algorithm is testified by IEEE 14-bus system and a practical 181-bus system.  相似文献   

7.
In field trials on the Loess Plateau, China, in 2012–13, maize (Zea mays L.) and soybean (Glycine max L.) were sole cropped and intercropped at three densities and with three sowing proportions. Maize was generally more growth efficient for biomass accumulation than soybean during the entire growth interval, as assessed using the relative efficiency index (REIc). However, most of sowing proportion at each density displayed a trend of decreased growth with development. Throughout the growth period, the dry matter production and leaf area index (LAI) of maize increased as the plant density increased irrespective of whether it was grown as a sole crop or as an intercrop. However, the effect of increasing cropping density was less obvious for soybean. The LAI values of the sole crop treatment for both maize and soybean were greater than that of the intercropping system, indicating that the presence of maize and soybean together suppressed the respective growth of the two crops. At the final harvest, land equivalent ratios (LER) of 0.84–1.35 indicated resource complementarity in most of the studied intercrops. Complementarity was directly affected by changes in plant densities; the greatest LER were observed in 2 rows maize and 2 rows soybean intercrops at low density. The water equivalent ratio (WER), which characterized the efficiency of water resource use in intercropping, ranged from 0.84 to 1.68, indicating variability in the effect of intercropping on water-use efficiency (WUE).  相似文献   

8.
The paper presents a novel continuously adjustable Peterson coil. If it is used in the system of neutral point grounding through Peterson coil, not only the high price can be reduced and the complicated problems can be solved of which the high voltage inductance controlling systems, but also advantages of the system of neutral point grounding though Peterson coil can be shown. It is introduces that how adopts low voltage thyristors for continuing adjusting inductance of the Peterson coil of which the voltage level ranges from 6 kV to 66 kV. This paper discusses the formula of calculating the inductance variable ranges and the harmonic currents which presents stable harmonic current under the phase controlled mode also. The theory of the designing coil is verified by the Saber simulation and practicality experiment.  相似文献   

9.
Equivalent couple stresses and non-symmetric equivalent stresses are introducedto describe the equivalent constitutive equation of honeycomb materials within plane deformation.Itis necessary for the materials of macroscopic polarity induced by some mesostructures.  相似文献   

10.
Improves investment decision method NPV method by introducing risk. This paper CAPM and certainty equivalent wealthare applied because of NCF'S volatility of venture capital projects, on the basis of which, debt capital is introduced. the dissertation derives a levered risky project's NPV formula, which broadens applying range and lessens constrain conditions. For risky projects investment decision, the research provides a new theoretical basis.  相似文献   

11.
The secondary moment of prestressed concrete frame is different from that of continuous beam. In this paper,the principle and calculation method of equivalent load secondary moment and axial secondary moment are discussed,and the infection of secondary moment in moment modulation is analyzed,together with the suggestions of moment modulation for prestressed concrete frame with adopting the total control. The suggestions would be able to distinguish the advantageous and disadvantageous effect of secondary moment. Some helpful advises for moment modulation design are given in this paper.  相似文献   

12.
Equivalent linear system method is the main method of nonlinear structural system random response analysis. While it would generate big error when the results of equivalent linear system method are used to analyze the structural dynamic reliability. Through minimum mean square error principle, general nonlinear system was converted to equivalent Duffing nonlinear system, based on which the structural dynamic reliability was analyzed. The accurate steady state analytic solution of Duffing nonlinear system can be worked out by FPK equation, so it is not only convenient but also accurate to analyze structural dynamic reliability by using the equivalent nonlinear system method. It is also shown that the analysis results of equivalent nonlinear system method presented here is reliable and the calculation accuracy is higher than equivalent linear system method apparently through the example analysis.  相似文献   

13.
Fast modeling of the motor broadband equivalent circuit model   总被引:2,自引:0,他引:2  
This paper proposes a modeling method of the motor broadband equivalent circuit model. The impedance amplitude-frequency characteristics of the motor terminal through measuring are obtained. The impedance amplitude-frequency characteristics are devided into several regions based on its first resonant point information,and the motor broadband circuit topology is developed with each region equaling a resonance unit. The RLC parameters of resonance unit are extracted through frequency and corresponding impedance of the any non-resonant and resonant point in each unit. This proposed method is used to build DC and AC motor broadband equivalent circuit model. Their impedance amplitude-frequency characteristics are simulated by the Saber software. The measurement results and the simulation result of references are compared. The DC motor simulation results coincide with the measurement results in 0.1~50 MHz,and the AC motor is in 0.1~40 MHz. The results show that the motor broadband circuit model is reliable and feasible.  相似文献   

14.
Isolation technique was not only applied for middle or low buildings, but also recently it was applied to high rise buildings. For high rise buildings, multi order vibration should be considered for upper structure isolation and bend deformation should be taken into account in gross deformation because of large height to width ratio. On the basis of previous studies, calculation method of equivalent model for regular isolated structure with bend shear deformation characteristic was proposed according to equivalent criteria after the analysis for some model structures. With the proposed model, handwork calculation of earquake response for isolated structure can be simply completed and design efficiency of isolation structure was improved. Based on the case studies, the equivalency of proposed model was approved.  相似文献   

15.
An experiment was conducted during rainy season (April-August) of 1994 and 1995 to assess the performance of rice, maize, sesame, greengram and blackgram grown in sole and intercropping system on Gangetic alluvial upland (Entisol) in West Bengal. India. All intercropping systems except sesame + rice had higher total productivity in terms of rice equivalent yield and net returns than all the sole crops. However, maximum advantage was obtained from paired row planted maize blackgram system followed by maize + sesame, maize + blackgram and paired row planted rice + blackgram. Paired row planted maize + blackgram increased land use efficiency (42%), rice equivalent yield (2955 kg ha−1), monetary return (Rs. 7294 ha−1), income equivalent ratio (1.22), monetary advantage (Rs. 3701 ha−1) compared with other cropping systems, which proved to be the most efficient system. The same treatment also indicated a modest competitive ratio (4.65:0.21) and gave a good value for the product of crowding coefficient (8.28).  相似文献   

16.
基于等效原则、相似理论,考虑三维地震动作用下振动台试验中原型结构隔震层的简化,并对模型结构隔震层进行系统研究。针对不同高宽比隔震结构,提出完全等效简化方法和部分等效简化方法,包括隔震垫等效、模型支座参数及坐标确定、相似关系确定等。利用不同高宽比隔震结构振动台试验,结合有限元数值模拟,进行方法验证。理论推导与数值模拟证明简化方法具有良好的准确性,且在误差允许范围内,简化后的隔震层所获得的加速度、速度、位移等动力特性与简化前相同,可以用于振动台试验模型设计。  相似文献   

17.
Grounded on the theory of power equilibrium, a novel single phase series active power filter (APF) is proposed . By analyzing the power equilibrium character of series APF, the control algorithm and equation are deduced. In the proposed control strategy, instead of the fundamental current detection and complex computation, only the capacitance voltage and the source current on d.c. side are needed. The clear control loop has been realized with simple circuit and the series proposed APF can compensate both reactive and harmonic current simultaneously. The simulation results show the excellent compensation effect and confirm the validity of theoretical analysis.  相似文献   

18.
Influence of Transverse Flexural Crack on Chloride Penetration in Concrete   总被引:1,自引:0,他引:1  
The mechanism for chloride penetration in cracked concrete and its major impact factors were analyzed. As a result, a revised chloride diffusion model based on Fick's Law was built by dual porous medium model. Then several cracked reinforced concrete beams self-anchored with sustained flexural loads were immersed in the 5% NaCl solution with the condition of dry-wet cycles. After 15 times of dry-wet cycles, the rapid chloride testing (RCT) was used for the determination of chloride ion content of the powder at each cracked sections. The test results show that: 1) with the condition of dry-wet cycles, the chloride content will occur a peak in the surface 20mm concrete, so the depth for surface convection zone can be assumed to be 15~20 mm; 2) when the crack width is less than 0.3mm, the equivalent chloride diffusion coefficient increases steadily, which agrees well with model's prediction; when the crack width is larger than 0.3mm, the equivalent chloride diffusion coefficient augments rapidly and influence of convection on chloride penetration becomes more significant; 3) the deterioration factor for equivalent chloride diffusion coefficient in flexural cracked concrete is directly correlative with crack width, which can be expressed by second order power function or separate function.  相似文献   

19.
以国槐槐角培养出的愈伤组织为试材,以槐角苷为标准品,利用紫外可见光分光光度法研究乙醇浸提法提取国槐槐角愈伤组织中异黄酮的工艺条件。在单因素试验的基础上,设计了L9(34)(4因素3水平)的正交试验。研究结果表明:乙醇浸提法提取槐角异黄酮的最佳工艺条件为:提取温度75℃;提取时间9 h;提取乙醇浓度60%;提取的液料比70∶1,槐角异黄酮的最大提取量为:12.045 mg/g。  相似文献   

20.
It is very essential to extract representative frames in the process of generating video summary. A method is proposed which analyses the color features of the video frames, sets the connectivity threshold values automatically according to the contents, extracts the color coherence vectors (CCV) and then performs adaptive clustering based on equivalent relation. After global partition, local partition was revised with time sequential features. The whole process does not need to set any threshold values. The experiments with diverse videos yields effective results.  相似文献   

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