Temporal and Spatial Variations of ET 0 and Sensitivity Coefficients in Spring-summer in Eastern Agricultural Areas of Qinghai,China

Reference crop evapotranspiration(ET 0) is a key parameter to calculate crop water requirements.In the paper,ET 0 during 1960-2005 was calculated with FAO-56 PM in eastern agricultural areas of Qinghai,China.Then the sensitivity coefficients of ET 0 to meteorological variables were estimated through the nondimensional partial derivative in FAO-56 PM.Results show that the mean annual ET 0 of the whole area is 904 mm,and ET 0 portrays a very significant decrease during the 46 years.In spatial,ET 0 decreases from southeast to northwest,firstly increases then decreases from southwest to northeast.Through sensitivity analysis,in spring the most sensitive variable is relative humidity,while in summer is temperature.The temperature,sunshine duration and wind speed sensitivity coefficients(S(TA),S(n),S(u)) are higher in middle areas as opposed to surrounding areas,while the relative humidity sensitivity coefficient(S(RH)) has an opposite distribution rule.

Spatiotemporal Characteristics of Reference Evapotranspiration and Its Sensitivity Coefficients to Climate Factors in Huang-Huai-Hai Plain,China

Climate change will have important implications in water shore regions,such as Huang-Huai-Hai（3H） plain,where expected warmer and drier conditions might augment crop water demand.Sensitivity analysis is important in understanding the relative importance of climatic variables to the variation in reference evapotranspiration（ET 0）.In this study,the 51-yr ET 0 during winter wheat and summer maize growing season were calculated from a data set of daily climate variables in 40 meteorological stations.Sensitivity maps for key climate variables were estimated according to Kriging method and the spatial pattern of sensitivity coefficients for these key variables was plotted.In addition,the slopes of the linear regression lines for sensitivity coefficients were obtained.Results showed that ET 0 during winter wheat growing season accounted for the largest proportion of annual ET 0,due to its long phenological days,while ET 0 was detected to decrease significantly with the magnitude of 0.5 mm yr-1in summer maize growing season.Solar radiation is considered to be the most sensitive and primarily controlling variable for negative trend in ET 0 for summer maize season,and higher sensitive coefficient value of ET 0 to solar radiation and temperature were detected in east part and southwest part of 3H plain respectively.Relative humidity was demonstrated as the most sensitive factor for ET 0 in winter wheat growing season and declining relativity humidity also primarily controlled a negative trend in ET 0,furthermore the sensitivity coefficient to relative humidity increased from west to southeast.The eight sensitivity centrals were all found located in Shandong Province.These ET 0 along with its sensitivity maps under winter wheat-summer maize rotation system can be applied to predict the agricultural water demand and will assist water resources planning and management for this region.

SENSITIVITY COEFFICIENTS OF SINGLE-PHASE FLOW IN LOW-PERMEABILITY HETEROGENEOUS RESERVOIRS

Theoretical equations for computing sensitivity coefficients of wellbore pressures to estimate the reservoir parameters in low-permeability reservoirs conditioning to non-Darcy flow data at low velocity were obtained. It is shown by a lot of numerical calculations that the wellbore pressures are much more sensitive to permeability very near the well than to permeability a few gridblocks away from the well. When an initial pressure gradient existent sensitivity coefficients in the region are closer to the active well than to the observation well. Sensitivity coefficients of observation well at the line between the active well and the observation well are influenced greatly by the initial pressure gradient.

Sensitivity of Penman-Monteith Reference Crop Evapotranspiration in Tao'er River Basin of Northeastern China

A non-dimensional relative sensitivity coefficient was employed to predict the responses of reference crop evapotranspiration (ET0) to perturbation of four climate variables in Tao'er River Basin of the northeastern China. Mean monthly ET0 and yearly ET0 from 1961 to 2005 were estimated with the FAO-56 Penman-Monteith Equation. A 45-year historical dataset of average monthly maximum/minimum air temperature, mean air temperature, wind speed, sunshine hours and relative humidity from 15 meteorological stations was used in the analysis. Results show that: 1) Sensitivity coefficients of wind speed, air temperature and sunshine hours were positive except for those of air tem- perature of Arxan Meteorological Station, while those of relative humidity were all negative. Relative humidity was the most sensitive variable in general for the Tao'er River Basin, followed by sunshine hours, wind speed and air tem- perature. 2) Similar to climate variable, monthly sensitivity coefficients exhibit large annual fluctuations. 3) Sensitivity coefficients for four climate variables all showed significant trends in seasonal/yearly series. Also, sensitivity coefficients of air temperature, sunshine hours and wind speed all showed significant trends in spring. 4) Among all sensitiv- ity coefficients, the average yearly sensitivity coefficient of relative humidity was highest throughout the basin and showed largest spatial variability. Longitudinal distribution of sensitivity coefficients for air temperature, relative hu- midity and sunshine hours was also found, which was similar to the distribution of the three climate variables.

Irradiation effect on strain sensitivity coefficient of strain sensing fiber Bragg gratings

The effect of irradiation on the strain sensitivity coefficient of strain sensing fiber Bragg gratings （FBGs） has been investigated through experiments. FBGs were fabricated in single mode fibers with 3 tool% Ge-concentration in the core and with a H2-1oading treatment. In experiments, the FBGs were subjected to y-radiation exposures using a Co6~ source at a dose-rate of 25 Gy/min up to a total dose of 10.5 kGy. The GeO defect in fiber absorbs photons to form a GeE＇ defect; the interaction with H2 is a probable reason for the y-radiation sensitivity of gratings written in hydrogen loaded fibres, The effect mechanism of radiation on the strain sensitivity coefficient is similar to that of radiation on the temperature sensitivity coefficient. Radiation affects the effective index neff, which results in the change of the thermo-optic coefficient and the strain-optic coefficient. Irradiation can change the strain sensitivity coefficient of FBGs by 1.48%-2.71%, as well as changing the Bragg wavelength shift （BWS） by 22 pm-25 pm under a total dose of 10.5 kGy. Our research demonstrates that the effect of irradiation on the strain sensitivity coefficient of FBG is small and that strain sensing FBGs can work well in the radiation environment.

Optimal configuration strategy of energy storage system in high photovoltaic penetration micro-grid based on voltage sensitivity analysis

Energy storage is an effective measure to deal with internal power fluctuation of micro-grid and ensure stable operation, especially in the micro-grid with high photovoltaic(PV) penetration. Its capacity configuration is related to the steady, safety and economy of micro-grid.In order to improve the absorptive capacity of micro-grid on maximizing the use of distributed PV power in micro-grid, and improve the power quality, an optimal energy storage configuration strategy is proposed, which takes many factors into account, such as the topology of micro-grid, the change of irradiance, the load fluctuation and the cable. The strategy can optimize the energy storage allocation model to minimize the storage power capacity and optimize the node configuration.The key electrical nodes are identified by using the sensitivity coefficient of the voltage, and then the model is optimized to simplify calculation. Finally, an example of the European low-voltage micro-grid and a micro-grid system in the laboratory is used to verify the effectiveness of the proposed method.The results show that the proposed method can optimize the allocation of capacity and the node of the energy storage system.

Reliability Sensitivity-based Correlation Coefficient Calculation in Structural Reliability Analysis

The correlation coefficients of random variables of mechanical structures are generally chosen with experience or even ignored,which cannot actually reflect the effects of parameter uncertainties on reliability.To discuss the selection problem of the correlation coefficients from the reliability-based sensitivity point of view,the theory principle of the problem is established based on the results of the reliability sensitivity,and the criterion of correlation among random variables is shown.The values of the correlation coefficients are obtained according to the proposed principle and the reliability sensitivity problem is discussed.Numerical studies have shown the following results：（1） If the sensitivity value of correlation coefficient ρ is less than（at what magnitude 0.000 01）,then the correlation could be ignored,which could simplify the procedure without introducing additional error.（2） However,as the difference between ρs,that is the most sensitive to the reliability,and ρR,that is with the smallest reliability,is less than 0.001,ρs is suggested to model the dependency of random variables.This could ensure the robust quality of system without the loss of safety requirement.（3） In the case of ｜Eabs｜ρ0.001 and also ｜Erel｜ρ0.001,ρR should be employed to quantify the correlation among random variables in order to ensure the accuracy of reliability analysis.Application of the proposed approach could provide a practical routine for mechanical design and manufactory to study the reliability and reliability-based sensitivity of basic design variables in mechanical reliability analysis and design.

The Interstorey Drift Sensitivity Coefficient in Calculating Seismic Building Frames

In calculating the seismic response of a building, the Spanish Instructions NCSE-02 and CTE, paragraph 3.7.7 （also EUROCODE 8 paragraph 1.2 part 1-1）, establish that if for all storeys the interstorey drift sensitivity coefficient, ζ, is less than or equal to 0.1, then it will not be necessary to consider the effects of the 2nd order （ P-△ effects）. In this paper the authors review this claim, because even for ≤0.1, increases of the bending moment at the ends of the columns due to the inclusion of second order effects can account for between 15% and 34% of its value for static service loads. This is significant since most adverse effects are shown in the lower height buildings （up to 5 floors） which it is precisely the range in which most of the housing stock of Spain is located. Finally, the authors delimit the coefficient for buildings of lesser height （up to 5 floors）, proposing to lower it generally to ζ≤ 006.

Soil Pressure Mini-sensor Made of Monocrystalline Silicon and the Measurement of Its Sensitivity Coefficient

A calibration test was done in order to measure its sensitivity coefficient by an improved soil test device.The experimental result shows that the soil pressure min-sensor made of the monocrystalline silicon（SPMMS）is proved to be good linear,high precision and less that can fetch precise data in low pressure range even near by O point,which guarantees the reliability of the soil pressure test in geotechnical engineering.

Study on the Ecosystem Services Value of Fei County Based on RS and GIS

[Objective] With the background of dramatic changes in land use patterns,the aim was to explore the ecosystem services value of Fei County based on RS and GIS.[Method] Ecological changes in the environment can bring changes in economic value expressed quantitatively by ecosystem service value （ESV）.According to modified ESV equivalency factor tables and three periods of interpreted TM remote sensing images in 1990,2000 and 2009,this paper calculated the total ESV in Fei County,Shandong Province,China and analyzed the relationship between ESV and the land-use changes at last.[Result] The results showed that the total ESV of the study area decreased from 2.144×109 yuan in 1990,2.139×109 yuan in 2000,and at last to 2.098×109 yuan in 2009 as the overall study area land use pattern changed dramatically,in which the built-up land increased by 23％,while the cropland and forest were constantly on the decrease.[Conclusion] The research provides theoretical support for the construction of high efficient ecological economic zone and sustainable development of the region.

Sensitivity Analysis of the Hydrodynamic Coefficients in 4 Degrees of Freedom Ship Manoeuvring Mathematical Model

The S-type test is simulated based on a ship manoeuvring mathematical model of 4 degrees of freedom(4-DOF);simultaneously,sensitivity analysis of the hydrodynamic coefficients in the mathematical model is implemented by using an indirect method.The mathematical model is simplified by omitting the coefficients of smaller sensitivity according to the results of sensitivity analysis.The 10°/10° zigzag test and 35° turning circle manoeuvre are simulated with the original and the simplified mathematical models.The comparison of the simulation results shows the effectiveness of the sensitivity analysis and the validity of the simplified model.

Plastic equation of state determined by nano indentation

In order to characterize the plastic state of a deformed material, an indentation method to determine the plastic equation of state(PES) was developed. The work-hardening coefficient and the strain rate sensitivity coefficient of the plastic mechanic equation of state were determined by two kinds of indentation tests respectively. Therefore, the PES of materials under deformation can be obtained, and the plastic state of materials can be determined.

Determination of plastic equation of state by indentation method on 304 stainless steel

An indentation method for determining the plastic mechanical equation of state (PES) was studied. The constant loading rate and constant loading rate/load indentation tests were carried out. The method for determining the work-hardening coefficient and the strain rate sensitivity coefficient of PES were discussed in detail. 304 stainless steel hot-treated at 1100°C was used to verify the method. The work-hardening coefficient and strain rate sensitivity coefficient of 304 stainless steel were respectively determined as 0.30 and 0.015. These values are very close to those achieved by tensile tests. From the establishment of the PES of 304 stainless steel it is shown that the PES obtained by the indentation method is easier than that by the tensile test.

Is the Two-Color Method Superior to Empirical Equations in Refractive Index Compensation?

The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive index of air. However, it is not well known whether the two-color method is superior to empirical equations in refractive index compensation. We investigated the uncertainties of these approaches via numerical calculations of their sensitivity coefficients of environmental parameters. On the basis of a comparison of their uncertainties, we found that in a 0% humidity environment, the two-color method had potential to provide greater measurement accuracy than the empirical equations.

Ice-covered Environmental Adaptability Assessment for Overhead Contact System in High-speed Railways

High-speed trains rely on pantograph-catenary systems(PCSs)to collect electrical energy from power systems.However,the dynamic interaction between the pantograph and the catenary system may become mismatched once ice accumulates on the overhead conductors.More frequent arcing may occur within the PCS during train operation,posing an unpredictable threat to operational safety.Therefore,it is crucial to evaluate the ability of overhead contact system(OCS)to withstand ice-covered variability during line desgin.A new strategy is proposed to evaluate the adaptive performance of an OCS under various icing conditions.First,a dynamic model considering icing conditions is constructed to simulate the interaction within the PCS.Five different OCS structures with various icing thicknesses are studied.The parameters of the contact force within the PCS and proportion of high-possibility arcing moments are obtained.The dependence of the contact force on the icing thickness and pantograph displacement has been illustrated in the form of cloud maps.Finally,the OCS sensitivity coefficient is calculated,and ice-covered environmental adaptability assessments for the five different OCS structures are compared.

An efficient sensitivity analysis for energy performance of building envelope: A continuous derivative based approach

Within the framework of building energy assessment,this article proposes to use a derivative based sensitivity analysis of heat transfer models in a building envelope.Two,global and local,estimators are obtained at low computational cost,to evaluate the influence of the parameters on the model outputs.Ranking of these estimators values allows to reduce the number of model unknown parameters by excluding non-significant parameters.A comparison with variance and regression-based methods is carried out and the results highlight the satisfactory accuracy of the continuous-based approach.Moreover,for the carried investigations the approach is 100 times faster compared to the variance-based methods.A case study applies the method to a real-world building wall.The sensitivity of the thermal loads to local or global variations of the wall thermal properties is investigated.Additionally,a case study of wall with window is analyzed.

Impact of Climate Change on Maize Potential Productivity and the Potential Productivity Gap in Southwest China

The impact of climate change on maize potential productivity and the potential productivity gap in Southwest China（SWC） are investigated in this paper.We analyze the impact of climate change on the photosynthetic,light-temperature,and climatic potential productivity of maize and their gaps in SWC,by using a crop growth dynamics statistical method.During the maize growing season from 1961 to 2010,minimum temperature increased by 0.20℃ per decade（p 〈 0.01） across SWC.The largest increases in average and minimum temperatures were observed mostly in areas of Yunnan Province.Growing season average sunshine hours decreased by 0.2 h day^（-1） per decade（p 〈 0.01） and total precipitation showed an insignificant decreasing trend across SWC.Photosynthetic potential productivity decreased by 298 kg ha^（-1）per decade（p 〈 0.05）.Both light-temperature and climatic potential productivity decreased（p 〈 0.05） in the northeast of SWC,whereas they increased（p 〈 0.05） in the southwest of SWC.The gap between lighttemperature and climatic potential productivity varied from 12 to 2729 kg ha^（-1）,with the high value areas centered in northern and southwestern SWC.Climatic productivity of these areas reached only 10%-24%of the light-temperature potential productivity,suggesting that there is great potential to increase the maize potential yield by improving water management in these areas.In particular,the gap has become larger in the most recent 10 years.Sensitivity analysis shows that the climatic potential productivity of maize is most sensitive to changes in temperature in SWC.The findings of this study are helpful for quantification of irrigation water requirements so as to achieve maximum yield potentials in SWC.

Temperature characteristics research of SOI pressure sensor based on asymmetric base region transistor

Based on the asymmetric base region transistor, a pressure sensor with temperature compensation circuit is proposed in this paper. The pressure sensitive structure of the proposed sensor is constructed by a C-type silicon cup and a Wheatstone bridge with four piezoresistors（R_1, R_2, R_3 and R_4/locating on the edge of a square silicon membrane. The chip was designed and fabricated on a silicon on insulator（SOI） wafer by micro electromechanical system（MEMS） technology and bipolar transistor process. When the supply voltage is 5.0 V, the corresponding temperature coefficient of the sensitivity（TCS） for the sensor before and after temperature compensation are -1862 and -1067 ppm/℃, respectively. Through varying the ratio of the base region resistances r_1 and r_2, the TCS for the sensor with the compensation circuit is -127 ppm/℃. It is possible to use this compensation circuit to improve the temperature characteristics of the pressure sensor.