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61.
The study assessed the causal effects of NERICA adoption on rice yields and income, using country-wide data of 600 rice farmers
in The Gambia. To control for differences in socio-demographic and environmental characteristics of adopters and non-adopters
and enable a causal interpretation of NERICA adoption on the variables of interest, the study used the counterfactual outcome
framework to control for such differences. The results, based on observed sample estimates, showed significant differences
in rice yields and income between the NERICA adopters and non-adopters. Further, the results of the framework, based on the
Local Average Treatment Effect (LATE) estimates, which allowed a causal interpretation, showed that NERICA adoption significantly
increased average rice yields and annual income of small-scale rice farmers by 157 kg per hectare and $148, respectively. 相似文献
62.
Fred C. Leone 《技术计量学》2013,55(2):301-304
Eight-run two level factorial and fractional factorial designs are examined from two points of view: (1) the number of levels which must be changed in performing the design, (2) the effect of a first order time trend on the main effects. It is found that only a few run orders are desirable from these viewpoints and thus randomization of the runs is likely, in general, to lead to an unfavorable sequence. 相似文献
63.
Fred C. Leone 《技术计量学》2013,55(3):443-446
It is pointed out that the inferential theory of the segmented regression model depends strongly on whether or not continuity at the change-point is assumed. In particular, if it is not, the likelihood ratio test for the presence of two segments tends to infinity. 相似文献
64.
Fred C. Leone 《技术计量学》2013,55(1):145-149
Two objectives of much experimentation in science and engineering are (i) to establish the form of an adequate mathematical model for the system being investigated and (ii) to obtain precise estimates of the model parameters. In the past, statistical design procedures have been proposed for tackling either one of these problems separately. Investigators, however, frequently want to perform experiments which will shed light on both questions simultaneously. In this paper, therefore, we present a design criterion which takes both objectives into account. The basic design strategy is to emphasize model discrimination when there is considerable doubt as to which model is best and gradually shifting the emphasis to parameter estimation as experimentation progresses and discrimination is accomplished. It is assumed that experiments can be performed sequentially. The use of the design criterion is illustrated with an example. 相似文献
65.
Deepak K. Gupta Fred van Keulen Matthijs Langelaar 《International journal for numerical methods in engineering》2020,121(3):450-476
Multiresolution topology optimization (MTO) methods involve decoupling of the design and analysis discretizations, such that a high-resolution design can be obtained at relatively low analysis costs. Recent studies have shown that the MTO method can be approximately 3 and 30 times faster than the traditional topology optimization method for two-dimensional (2D) and three-dimensional (3D) problems, respectively. To further exploit the potential of decoupling analysis and design, we propose a dp-adaptive MTO method, which involves locally increasing/decreasing the polynomial degree of the shape functions (p) and the design resolution (d). The adaptive refinement/coarsening is performed using a composite refinement indicator that includes criteria based on analysis error, presence of intermediate densities, as well as the occurrence of design artifacts referred to as QR-patterns. While standard MTO must rely on filtering to suppress QR-patterns, the proposed adaptive method ensures efficiently that these artifacts are suppressed in the final design, without sacrificing the design resolution. The applicability of the dp-adaptive MTO method is demonstrated on several 2D mechanical design problems. For all the cases, significant speedups in computational time are obtained. In particular for design problems involving low material volume fractions, speedups of up to a factor of 10 can be obtained over the conventional MTO method. 相似文献
66.
Fred Gassner 《Geotextiles and Geomembranes》2017,45(6):702-706
The paper describes the authors experience with the formation of geomembrane liner hippos, which is the spherical deformation of the liner within a liquid or viscous medium. The paper presents a summary of six case histories, describing the key features of the hippo and how it formed. The paper also describes the management measures introduced to address the hippo feature. 相似文献
67.
The phenomenon of all-elements-sleeping-beauties in science is revealed by four special cases. The ??sleeping beauties?? prick their fingers on the ??spindles?? so that they fall into sleep then are awakened by their ??princes??. The authors speculate that the phenomenon could happen in scientific literatures with high quality. 相似文献
68.
Hugo Plácido da Silva André Lourenço Ana Fred Nuno Raposo Marta Aires-de-Sousa 《Computer methods and programs in biomedicine》2014
The Check Your Biosignals Here initiative (CYBHi) was developed as a way of creating a dataset and consistently repeatable acquisition framework, to further extend research in electrocardiographic (ECG) biometrics. In particular, our work targets the novel trend towards off-the-person data acquisition, which opens a broad new set of challenges and opportunities both for research and industry. While datasets with ECG signals collected using medical grade equipment at the chest can be easily found, for off-the-person ECG data the solution is generally for each team to collect their own corpus at considerable expense of resources. In this paper we describe the context, experimental considerations, methods, and preliminary findings of two public datasets created by our team, one for short-term and another for long-term assessment, with ECG data collected at the hand palms and fingers. 相似文献
69.
How does the analyst understand his or her patient’s lack of response to events precipitated by the analyst, especially absences? The author offers an explanation based on a unique form of caring. A. Green’s (1972) concept of the dead mother is crucial to this understanding, as is the distinction among hate, love, and care. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
70.