期刊文献+
共找到1,855篇文章
< 1 2 93 >
每页显示 20 50 100
Study on the Ecosystem Services Value of Fei County Based on RS and GIS 被引量:1
1
作者 崔敬涛 吴国平 +2 位作者 马庆申 范庆亚 汪佳莉 《Agricultural Science & Technology》 CAS 2013年第8期1171-1173,1177,共4页
[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 c... [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. 展开更多
关键词 Ecosystem services value coefficient of sensitivity RS and GIS Feicounty
下载PDF
中国人均CO_2排放水平地区差异的成因分析——基于GINI系数和回归的Shapley Value分解方法 被引量:1
2
作者 柳亚琴 赵国浩 《生态经济》 CSSCI 北大核心 2015年第4期47-50,106,共5页
根据2000-2011年中国省际面板数据,以GINI系数为衡量指标,测算了人均CO2排放水平的地区差异,分析了人均CO2排放水平随时间的演变趋势,在此基础上采用基于回归的Shapley Value分解方法,对中国人均CO2排放水平地区差异形成原因进行了考察... 根据2000-2011年中国省际面板数据,以GINI系数为衡量指标,测算了人均CO2排放水平的地区差异,分析了人均CO2排放水平随时间的演变趋势,在此基础上采用基于回归的Shapley Value分解方法,对中国人均CO2排放水平地区差异形成原因进行了考察,探究各影响因素对差异程度的影响水平,从而为有效缩小地区差异和制定CO2减排政策提供有益的参考。结果表明:人均能源消费量因素的影响程度最大,平均贡献率为72.80%,各省份的经济发展水平和产业结构是人均CO2排放水平省际差异的第二大贡献因素,其平均贡献率依次为8.01%与10.20%,且在不同的时间段其结果有所不同。排在第四位和第五位的因素分别是城镇化水平和对外开放水平,二者都是影响人均CO2排放水平省际差异的重要因素,平均贡献率分别达到5.17%与3.81%。 展开更多
关键词 人均CO2排放水平 GINI系数 差异分解 Shapley value方法
下载PDF
Importance of b value in diffusion weighted imaging for the diagnosis of pancreatic cancer 被引量:12
3
作者 Jin-Gang Hao Jia-Ping Wang +1 位作者 Ya-Lv Gu Ming-Liang Lu 《World Journal of Gastroenterology》 SCIE CAS 2013年第39期6651-6655,共5页
AIM:To investigate the use of multi-b-value diffusionweighted imaging in diagnosing pancreatic cancer.METHODS:We retrospectively analyzed 33 cases of pancreatic cancer and 12 cases of benign pancreatic tumors at the S... AIM:To investigate the use of multi-b-value diffusionweighted imaging in diagnosing pancreatic cancer.METHODS:We retrospectively analyzed 33 cases of pancreatic cancer and 12 cases of benign pancreatic tumors at the Second Affiliated Hospital of Kunming Medical University from December 2008 to January2011.The demographic characteristics,clinical presentation,routine magnetic resonance imaging and diffusion weighted imaging(DWI)features with different b values were reviewed.Continuous data were expressed as mean±SD.Comparisons between pancreatic cancer and benign pancreatic tumors were performed using the Student’s t test.A probability of P<0.05 was considered statistically significant.RESULTS:Thirty-three patients with pancreatic cancer were identified.The mean age at diagnosis was 60±5.6 years.The male:female ratio was 21:12.Twenty cases were confirmed by surgical resection and 13 by biopsy of metastases.T1 weighted images demonstrated a pancreatic head mass in 16 patients,a pancreatic body mass in 10 cases,and a pancreatic tail mass with pancreatic atrophy in 7 cases.Eight patients had hepatic metastases,13 had invasion or envelopment of mesenteric vessels,4 had bone metastases,and 8had lymph node metastases.DWI demonstrated an irregular intense mass with unclear margins.Necrotic tissue demonstrated an uneven low signal.A b of 1100s/mm2was associated with a high intensity signal with poor anatomical delineation.A b of 700 s/mm2was associated with apparent diffusion coefficients(ADCs)that were useful in distinguishing benign and malignant pancreatic tumors(P<0.05).b values of 50,350,400,450 and 1100 s/mm2were associated with ADCs that did not differentiate the two tumors.CONCLUSION:Low b value images demonstrated superior anatomical details when compared to high b value images.Tumor tissue definition was high and contrast with the surrounding tissues was good.DWI was useful in diagnosing pancreatic cancer. 展开更多
关键词 PANCREATIC cancer Magnetic resonance IMAGING b value APPARENT DIFFUSION coefficient DIFFUSION weighted IMAGING
下载PDF
Effect of Methylene Blue (MB)-value of Manufactured Sand on the Durability of Concretes 被引量:5
4
作者 王稷良 NIU Kaimin +1 位作者 TIAN Bo SUN liqun 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2012年第6期1160-1164,共5页
The relation between the methylene blue (MB) value of MS and its limestone powder content and clay content was investigated. The effects of MB values ranging from 0.35 to 2.5 on the workability of fresh concrete, th... The relation between the methylene blue (MB) value of MS and its limestone powder content and clay content was investigated. The effects of MB values ranging from 0.35 to 2.5 on the workability of fresh concrete, the mechanical properties, the resistance to freezing as well as the resistance to chlorine ion permeation of the hardened concrete were all investigated. The experimental results showed that the MB value had no correlation with the limestone powder content of MS, while it was directly related to the clay content. With an increase of MB value, concrete workability decreased, as did the flexural and 7-day compressive strengths, however, the 28-day compressive strength was not affected. Furthermore, influence of MB value on concretes of different strength levels was different. For low-strength concretes, an increase of MB value could improve its impermeability, but this was not the case for high-strength concretes. Instead, their resistance to chloride ion permeability decreased slightly. However, even a slight increase in MB value remarkably accelerated freeze-thaw damage of MS concrete. It was thus concluded that the critical MB value of 1.4 would not cause significant deterioration in the performance of MS concretes. 展开更多
关键词 manufactured sand methylene blue value clay content resistance to freezing chlorine ionpermeability coefficient
下载PDF
ON THE COEFFICIENTS OF DIFFERENTIATED EXPANSIONS AND DERIVATIVES OF CHEBYSHEV POLYNOMIALS OF THE THIRD AND FOURTH KINDS 被引量:3
5
作者 Eid H.DOHA Waleed M.ABD-ELHAMEED Mahmoud A.BASSUONY 《Acta Mathematica Scientia》 SCIE CSCD 2015年第2期326-338,共13页
Two new analytical formulae expressing explicitly the derivatives of Chebyshev polynomials of the third and fourth kinds of any degree and of any order in terms of Chebyshev polynomials of the third and fourth kinds t... Two new analytical formulae expressing explicitly the derivatives of Chebyshev polynomials of the third and fourth kinds of any degree and of any order in terms of Chebyshev polynomials of the third and fourth kinds themselves are proved. Two other explicit formulae which express the third and fourth kinds Chebyshev expansion coefficients of a general-order derivative of an infinitely differentiable function in terms of their original expansion coefficients are also given. Two new reduction formulae for summing some terminating hypergeometric functions of unit argument are deduced. As an application of how to use Chebyshev polynomials of the third and fourth kinds for solving high-order boundary value problems, two spectral Galerkin numerical solutions of a special linear twelfth-order boundary value problem are given. 展开更多
关键词 Chebyshev polynomials of the third and fourth kinds expansion coefficients generalized hypergeometric functions boundary value problems
下载PDF
Driving Force and Ecosystem Service Values Estimation in the Extreme Arid Region from 1975 to 2015:A Case Study of Alxa League,China 被引量:5
6
作者 XIE Jiali LU Zhixiang +1 位作者 XIAO Shengchun YAN Changzhen 《Chinese Geographical Science》 SCIE CSCD 2021年第6期1097-1107,共11页
The research on ecosystem service values(ESVs)estimation in arid region is weak.We took the Alxa League of China’s Inner Mongolia Autonomous Region,an extreme arid region,as an example and constructed an equivalent c... The research on ecosystem service values(ESVs)estimation in arid region is weak.We took the Alxa League of China’s Inner Mongolia Autonomous Region,an extreme arid region,as an example and constructed an equivalent coefficient method to assess its ESVs from 1975 to 2015,by determining the standard unit of ESVs and the basic equivalent of the value of different ecosystem services per unit area based on the regional characteristics,literature research,expert knowledge and land use data.The results show that the ESVs first decreased from 83170.4 million yuan(RMB)in 1975 to 82337.8 million yuan(RMB)in 2000 and then increased to84033.6 million yuan(RMB)in 2015,and the ESV of sparse grassland and desert account for about 33%and 29%of the total ESVs,respectively.Among the four service types,the regulating services,support services,supply services and cultural services account for66.5%,22.8%,6.0%and 4.7%,respectively.The changes of ESVs in Alxa League are determined by the socio-economic development and ecological changes.This study provides a new method to estimate the ESVs in arid region by integrating existing methods and regional characteristics,such as the cost of water for arid ecosystems. 展开更多
关键词 ecosystem service values equivalent coefficient method driving force arid region Alxa League China
下载PDF
Mathematical Proof of the Synthetic Running Correlation Coefficient and Its Ability to Reflect Temporal Variations in Correlation 被引量:2
7
作者 ZHAO Jinping CAO Yong +1 位作者 SHI Yanyue WANG Xin 《Journal of Ocean University of China》 SCIE CAS CSCD 2021年第3期562-572,共11页
The running correlation coefficient(RCC)is useful for capturing temporal variations in correlations between two time series.The local running correlation coefficient(LRCC)is a widely used algorithm that directly appli... The running correlation coefficient(RCC)is useful for capturing temporal variations in correlations between two time series.The local running correlation coefficient(LRCC)is a widely used algorithm that directly applies the Pearson correlation to a time window.A new algorithm called synthetic running correlation coefficient(SRCC)was proposed in 2018 and proven to be rea-sonable and usable;however,this algorithm lacks a theoretical demonstration.In this paper,SRCC is proven theoretically.RCC is only meaningful when its values at different times can be compared.First,the global means are proven to be the unique standard quantities for comparison.SRCC is the only RCC that satisfies the comparability criterion.The relationship between LRCC and SRCC is derived using statistical methods,and SRCC is obtained by adding a constraint condition to the LRCC algorithm.Dividing the temporal fluctuations into high-and low-frequency signals reveals that LRCC only reflects the correlation of high-frequency signals;by contrast,SRCC reflects the correlations of high-and low-frequency signals simultaneously.Therefore,SRCC is the ap-propriate method for calculating RCCs. 展开更多
关键词 running correlation coefficient synthetic running correlation coefficient time window comparability standard value
下载PDF
FREE BOUNDARY VALUE PROBLEM FOR THE CYLINDRICALLY SYMMETRIC COMPRESSIBLE NAVIER-STOKES EQUATIONS WITH DENSITY-DEPENDENT VISCOSITY 被引量:1
8
作者 连汝续 刘健 《Acta Mathematica Scientia》 SCIE CSCD 2016年第1期111-123,共13页
In this paper, we investigate the free boundary value problem (FBVP) for the cylindrically symmetric isentropic compressible Navier-Stokes equations (CNS) with density- dependent viscosity coefficients in the case... In this paper, we investigate the free boundary value problem (FBVP) for the cylindrically symmetric isentropic compressible Navier-Stokes equations (CNS) with density- dependent viscosity coefficients in the case that across the free surface stress tensor is balanced by a constant exterior pressure. Under certain assumptions imposed on the initial data, we prove that there exists a unique global strong solution which tends pointwise to a non-vacuum equilibrium state at an exponential time-rate as the time tends to infinity. 展开更多
关键词 cylindrically symmetric Navier-Stokes equations free boundary value problem density-dependent viscosity coefficients strong solution
下载PDF
ASYMPTOTIC BEHAVIOUR OF EIGENVALUES FOR THE DISCONTINUOUS BOUNDARY-VALUE PROBLEM WITH FUNCTIONAL-TRANSMISSION CONDITIONS 被引量:11
9
作者 O.Sh.Mukhtarov Department of Mathematics, Science and Arts Faculty, Gaziosmanpasa University, Tokat, TurkeyMustafa Kandemir Department of Mathematics, Faculty of A mas y a Education, Ondokuz Mayis University, Amasya, Turkey 《Acta Mathematica Scientia》 SCIE CSCD 2002年第3期335-345,共11页
In this study, the boundary-value problem with eigenvalue parameter generated by the differential equation with discontinuous coefficients and boundary conditions which contains not only endpoints of the considered in... In this study, the boundary-value problem with eigenvalue parameter generated by the differential equation with discontinuous coefficients and boundary conditions which contains not only endpoints of the considered interval, but also point of discontinuity and linear functionals is investigated. So, the problem is not pure boundary-value. The authors single out a class of linear functionals and find simple algebraic conditions on coefficients, which garantee the existence of infinit number eigenvalues. Also the asymptotic formulas for eigenvalues are found. 展开更多
关键词 Asymptotic behaviour of eigenvalues boundary-value problems functional-conditions discontinuous coefficients
下载PDF
Assessment of ecosystem services value in response to prevailing and future land use/cover changes in Lahore,Pakistan 被引量:2
10
作者 Mobeen Akhtar Yuanyuan Zhao +3 位作者 Guanglei Gao Qudsia Gulzar Azfar Hussain Abdus Samie 《Regional Sustainability》 2020年第1期37-47,共11页
Land use/cover changes(LUCCs)significantly affect ecosystem services(ESs)and their corresponding monetary value.ESs can be evaluated to analyze the ecological and environmental changes caused by LUCCs.This research ai... Land use/cover changes(LUCCs)significantly affect ecosystem services(ESs)and their corresponding monetary value.ESs can be evaluated to analyze the ecological and environmental changes caused by LUCCs.This research aims to estimate variations in the ecosystem services value(ESV)due to LUCCs in Lahore of Pakistan,and to offer information and recommendations to policy-makers concerned with the economic improvement of metropolis areas.We first investigated the historical LUCCs from 1990 to 2019,and then simulated the future land use/cover in 2030 and 2050 based on the CA-Markov model under three scenarios,including business-as-usual(BAU),rapid economic growth(REG),and coordinated environmental sustainability(CES).Subsequently,we evaluated the ESV from 1990 to 2050 and evaluated the historical and potential future ESV changes induced by LUCCs during 1990–2019 and 2019–2050,respectively.The results showed that,land use/cover exhibited an increase in built-up land and decreases in vegetation,water body,and unused land both in the past and future.The net ESV decreased from 58.26 million USD in 1990 to 50.31 million USD in 2019.In 2050,the decrease in ESV is most rapid under the REG scenario(decrease ESV of 7.13 million USD and decrease percentage of 14.18%),followed by the BAU(decrease ESV of 5.61 million USD and decrease percentage of 11.15%)and CES(decrease ESV of 5.18 million USD and decrease percentage of 10.30%)scenarios.For each ecosystem service type,the ESV of waste treatment decreased by 18.37%from 1990 to 2019,followed by soil formation and conservation(17.52%),biodiversity and maintenance(13.23%),climate regulation(11.80%),food production(11.69%),hydrological regulation(11.11%),and aesthetic value(3.07%).These outcomes indicate that continuous land use/cover planning should focus on regenerating aquatic areas and vegetation restoration. 展开更多
关键词 Ecosystem services Land use/cover changes Environmental sustainability CA Markov Urban expansion value coefficient
下载PDF
A new investigation on drift of base-line value in geomagnetic observation
11
作者 杨冬梅 高玉芬 +1 位作者 赵永芬 黄蔚北 《Acta Seismologica Sinica(English Edition)》 CSCD 1997年第4期80-85,共6页
A new explanation on drift of base line (BL) value in geomagnetic observation was presented by means of detailed analysis on BL value of H variometer at Tianshui Observatory from 1991 to 1995, in association with so... A new explanation on drift of base line (BL) value in geomagnetic observation was presented by means of detailed analysis on BL value of H variometer at Tianshui Observatory from 1991 to 1995, in association with some numerical simulation. It was confirmed that drift does not always exist. For variometers running normally for many years, drift appears to be zero. The temperature dependence of BL value is reversible below a certain temperature but irreversible above it. This irreversibility is the main reason that causes the BL value to show a monotonous declination with time, which has been mistaken for the drift in the past. As to the H variometer at Tianshui Observatory, no drift exists in BL value in these years. A new method was introduced to study the BL value variation with temperature by separating it into three parts. 展开更多
关键词 base line (BL) value DRIFT temperature coefficient
下载PDF
DIFFERENCE SCHEMES BASING ON COEFFICIENT APPROXIMATION
12
作者 牟宗泽 龙永兴 曲文孝 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2005年第4期539-546,共8页
In respect of variable coefficient differential equations, the equations of coefficient function approximation were more accurate than the coefficient to be frozen as a constant in every discrete subinterval. Usually,... In respect of variable coefficient differential equations, the equations of coefficient function approximation were more accurate than the coefficient to be frozen as a constant in every discrete subinterval. Usually, the difference schemes constructed based on Taylor expansion approximation of the solution do not suit the solution with sharp function. Introducing into local bases to be combined with coefficient function approximation, the difference can well depict more complex physical phenomena, for example, boundary layer as well as high oscillatory,with sharp behavior. The numerical test shows the method is more effective than the traditional one. 展开更多
关键词 boundary value problem EIGENvalue coefficient approximation local exact scheme
下载PDF
Diffusion-weighted Single-shot Echo Planar MR Imaging of Normal Human Prostate Using Different b Values
13
作者 石浩军 孔祥泉 +3 位作者 冯敢生 徐海波 刘定西 于群 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2008年第6期737-740,共4页
This study examined the effect of different b values on diffusion-weighted MR imaging (DWI) of human prostate by using single-shot spin echo echo planar imaging (SE-EPI) sequences, observed the normal appearances ... This study examined the effect of different b values on diffusion-weighted MR imaging (DWI) of human prostate by using single-shot spin echo echo planar imaging (SE-EPI) sequences, observed the normal appearances and measured apparent diffusion coefficient (ADC) values in anatomical regions of normal prostate. Twenty-four healthy volunteers (mean age: 32 y) were studied by using a 1.5T system with a phased array surface multicoil. Two kinds of single-shot SE-EPI sequence were used to perform DWI in the prostate in volunteers, with five b values being 0, 30, 300, 500 to 1000 s/mm2. The image quality with different imaging parameters was analyzed and the ADC values in anatomical regions of normal prostate were measured. DWI of prostate was successfully obtained in all volunteers. The images were of good quality, without artifacts containing pixels within the prostate. The contrast was good between the different anatomical regions of the prostatic gland, i.e., the peripheral zone (PZ), which exhibited higher signal intensity, and the central gland (CG). Signal intensity contrast was related to the magnitude of b values. The ADC values in PZ and CG were (1.27±0.22)×10-3 mm2/s and (1.01±0.17)×10-3 mm2/s,respectively. The ADC values were found to be significantly higher in PZ than in CG (P〈0.05, paired t-test). Significant differences were found between the slice-selecting component and both the read-out and phase-encoding components of the ADC values. It is concluded that SE-EPI is a suitable DWI sequence for human prostate. The contrast between PZ and CG is good when b values are low, while the diffusion and ADC values are accurate when b values are high. ADC values are higher in PZ than in CG in normal prostate. Diffusional anisotropy is present in normal prostatic tissue. 展开更多
关键词 PROSTATE magnetic resonance imaging diffusion-weighted imaging b value apparentdiffusion coefficient
下载PDF
Improving Numerical Weather Prediction in Low Latitudes by Optimizing Diffusion Coefficients
14
作者 刘金达 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1993年第3期345-352,共8页
The horizontal diffusion coefficients of the operational model (T42L9) in numerical weather prediction are optimized by the steepest descent search of multi-dimensional optimization. In order to improve prediction acc... The horizontal diffusion coefficients of the operational model (T42L9) in numerical weather prediction are optimized by the steepest descent search of multi-dimensional optimization. In order to improve prediction accuracy in low latitudes, the optimum horizontal diffusion coefficients are chosen, with changing variation of the basic diffusion coefficient with the passage of time, and later forecasts are also made better. In view of the averages of forecast verifications of 9 cases, the forecasts with optimum diffusion coefficients are an improvement on operational forecasts. It means that the forecasts are got much better with optimum values of some important parameters by optimization in numerical weather prediction. 展开更多
关键词 Multi-dimensional optimization Steepest descent search Optimum horizontal diffusion coefficients Optimum values of parameters
下载PDF
Estimates on the eigenvalues of complex nonlocal Sturm-Liouville problems
15
作者 SUN Fu LI Kun 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2023年第1期100-110,共11页
The present paper deals with the eigenvalues of complex nonlocal Sturm-Liouville boundary value problems.The bounds of the real and imaginary parts of eigenvalues for the nonlocal Sturm-Liouville differential equation... The present paper deals with the eigenvalues of complex nonlocal Sturm-Liouville boundary value problems.The bounds of the real and imaginary parts of eigenvalues for the nonlocal Sturm-Liouville differential equation involving complex nonlocal potential terms associated with nonlocal boundary conditions are obtained in terms of the integrable conditions of coefficients and the real part of the eigenvalues. 展开更多
关键词 Sturm-Liouville problem nonlocal potential complex valued coefficient non-real eigenvalue
下载PDF
A Method of Moment Approach in Solving Boundary Value Problems
16
作者 Hilal M. El Misilmani Karim Y. Kabalan +1 位作者 Mohamad Y. Abou-Shahine Mohammed Al-Husseini 《Journal of Electromagnetic Analysis and Applications》 2015年第3期61-65,共5页
Several available methods, known in literatures, are available for solving nth order differential equations and their complexities differ based on the accuracy of the solution. A successful method, known to researcher... Several available methods, known in literatures, are available for solving nth order differential equations and their complexities differ based on the accuracy of the solution. A successful method, known to researcher in the area of computational electromagnetic and called the Method of Moment (MoM) is found to have its way in this domain and can be used in solving boundary value problems where differential equations are resulting. A simplified version of this method is adopted in this paper to address this problem, and two differential equations examples are considered to clarify the approach and present the simplicity of the method. As illustrated in this paper, this approach can be introduced along with other methods, and can be considered as an attractive way to solve differential equations and other boundary value problems. 展开更多
关键词 Boundary value Problem Differential EQUATIONS METHOD of MOMENT GALERKIN METHOD WEIGHT coefficient
下载PDF
Speech Intelligibility Enhancement Algorithm Based on Multi-Resolution Power-Normalized Cepstral Coefficients(MRPNCC)for Digital Hearing Aids
17
作者 Xia Wang Xing Deng +2 位作者 Hongming Shen Guodong Zhang Shibing Zhang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第2期693-710,共18页
Speech intelligibility enhancement in noisy environments is still one of the major challenges for hearing impaired in everyday life.Recently,Machine-learning based approaches to speech enhancement have shown great pro... Speech intelligibility enhancement in noisy environments is still one of the major challenges for hearing impaired in everyday life.Recently,Machine-learning based approaches to speech enhancement have shown great promise for improving speech intelligibility.Two key issues of these approaches are acoustic features extracted from noisy signals and classifiers used for supervised learning.In this paper,features are focused.Multi-resolution power-normalized cepstral coefficients(MRPNCC)are proposed as a new feature to enhance the speech intelligibility for hearing impaired.The new feature is constructed by combining four cepstrum at different time–frequency(T–F)resolutions in order to capture both the local and contextual information.MRPNCC vectors and binary masking labels calculated by signals passed through gammatone filterbank are used to train support vector machine(SVM)classifier,which aim to identify the binary masking values of the T–F units in the enhancement stage.The enhanced speech is synthesized by using the estimated masking values and wiener filtered T–F unit.Objective experimental results demonstrate that the proposed feature is superior to other comparing features in terms of HIT-FA,STOI,HASPI and PESQ,and that the proposed algorithm not only improves speech intelligibility but also improves speech quality slightly.Subjective tests validate the effectiveness of the proposed algorithm for hearing impaired. 展开更多
关键词 Speech intelligibility enhancement multi-resolution power-normalized cepstral coefficients binary masking value hearing impaired
下载PDF
Evaluating agricultural water-use efficiency based on water footprint of crop values: a case study in Xinjiang of China
18
作者 HAI Yang LONG Aihua +3 位作者 ZHANG Pei DENG Xiaoya LI Junfeng DENG Mingjiang 《Journal of Arid Land》 SCIE CSCD 2020年第4期580-593,共14页
Efficient agricultural water use is crucial for food safety and water conservation on a global scale. To quantitatively investigate the agricultural water-use efficiency in regions exhibiting the complex agricultural ... Efficient agricultural water use is crucial for food safety and water conservation on a global scale. To quantitatively investigate the agricultural water-use efficiency in regions exhibiting the complex agricultural structure, this study developed an indicator named water footprint of crop values(WFV) that is based on the water footprint of crop production. Defined as the water volume used to produce a unit price of crop(m^3/CNY), the new indicator makes it feasible to directly compare the water footprint of different crops from an economic perspective, so as to comprehensively evaluate the water-use efficiency under the complex planting structure. On the basis of WFV, the study further proposed an indicator of structural water-use coefficient(SWUC), which is represented by the ratio of water-use efficiency for a given planting structure to the water efficiency for a reference crop and can quantitatively describe the impact of planting structure on agricultural water efficiency. Then, a case study was implemented in Xinjiang Uygur Autonomous Region of China. The temporal and spatial variations of WFV were assessed for the planting industries in 14 prefectures and cities of Xinjiang between 1991 and 2015. In addition, contribution rate analysis of WFV for different prefectures and cities was conducted to evaluate the variations of WFV caused by different influencing factors: agricultural input, climatic factors, and planting structure. Results from these analyses indicated first that the average WFV of planting industries in Xinjiang significantly decreased from 0.293 m^3/CNY in 1991 to 0.153 m^3/CNY in 2015, corresponding to an average annual change rate of –3.532%. WFV in 13 prefectures and cities(with the exception of Karamay) has declined significantly during the period of 1991–2015, indicating that agricultural water-use efficient has effectively improved. Second, the average SWUC in Xinjiang decreased from 1.17 to 1.08 m^3/CNY in the 1990 s, and then declined to 1.00 m^3/CNY in 2011–2015. The value of SWUC was highly consistent with the relative value of WFV in most prefectures and cities, showing that planting structure is one of the primary factors affecting regional agricultural water-use efficiency. Third, the contribution rate of WFV variations from human factors including agricultural input and planting structure was much more significant than that from climatic factors. However, the distribution of agricultural input and the adjustment of planting structure significantly differed among prefectures and cities, suggesting regional imbalances of agricultural development. This study indicated the feasibility and effectiveness of controlling agricultural water use through increasing technical input and rational selection of crops in the face of impending climate change. Specifically, we concluded that, the rational application of chemical fertilizers, the development of the fruit industry, and the strict restriction of the cotton industry should be implemented to improve the agricultural water-use efficiency in Xinjiang. 展开更多
关键词 agricultural input climatic factors contribution rate planting structure structural water-use coefficient water footprint of crop values
下载PDF
Audit Committee, Value Creation Efficiency and Capital Employed Efficiency
19
作者 Fanny Soewignyo Tonny Irianto Soewignyo 《Management Studies》 2018年第1期20-29,共10页
This study contributes a number of innovative and interesting empirical findings with a view of four audit committee characteristics to predict overall value creation efficiency and capital employed efficiency using v... This study contributes a number of innovative and interesting empirical findings with a view of four audit committee characteristics to predict overall value creation efficiency and capital employed efficiency using value added intellectual coefficient (VAICTM) method. Using purposive sampling, 34 property, real estate, and building construction firms listed on Indonesia Stock Exchange in 2011 were selected. Empirical findings could not provide a significant relationship between audit committee characteristics and the overall value creation efficiency as well as capital employed efficiency. This implies that currently, the number of members, number of meetings, number of independent commissioners, and accounting or finance expertise in audit committee cannot be expected as drivers of business value creation in Indonesian context, more specifically for property, real estate, and building construction industry. The overall lack of significant relationships may potentially result from limited human capacity, lack of financial expertise, and inadequate knowledge about the role of audit committee to add value to the business. 展开更多
关键词 audit committee capital employed efficiency VAICTM value added intellectual coefficient value creation efficiency
下载PDF
A VARIATIONAL METHOD FOR COMPUTING POTENTIAL COEFFICIENTS USING DIFFERENT TYPES OF GRAVIMETRIC DATA
20
作者 GUO Junyi 《Geo-Spatial Information Science》 1998年第1期60-62,共3页
In this paper,a variational method is presented for solving theclassical gravimetric,satellite gravimetric and satellite altimetric mixed typeboudary value problem to obtain the potential coefficients.According to thi... In this paper,a variational method is presented for solving theclassical gravimetric,satellite gravimetric and satellite altimetric mixed typeboudary value problem to obtain the potential coefficients.According to thisprinciple,classical gravimetric data(height measured by geometric levelling orheight triangulation),satellite gravimetric data(height measured by satellitegeodesy technique)and satellite altimetric data can be used jointly to calculate thepotential coefficients. 展开更多
关键词 BOUNDARY value problem potential coefficient VARIATIONAL method
全文增补中
上一页 1 2 93 下一页 到第
使用帮助 返回顶部