36,796 research outputs found
The Comparative Ethology and Evolution of the Sand Wasps. Howard E. Evans. Cambridge: Harvard University Press, 1966. xviii, 526 pp. $15.00.
Excerpt: In one sense, ethology is natural history. In a more restricted sense, it is the description and classification of behavior viewed as a necessary prerequisite to analysis. The analyses that follow become more and more physiological as the tangle of facts unravels so that the ethology of the field inevitably becomes the ethology of the laboratory
An applicational process for dynamic balancing of turbomachinery shafting
The NASA Lewis Research Center has developed and implemented a time-efficient methodology for dynamically balancing turbomachinery shafting. This methodology minimizes costly facility downtime by using a balancing arbor (mandrel) that simulates the turbomachinery (rig) shafting. The need for precision dynamic balancing of turbomachinery shafting and for a dynamic balancing methodology is discussed in detail. Additionally, the inherent problems (and their causes and effects) associated with unbalanced turbomachinery shafting as a function of increasing shaft rotational speeds are discussed. Included are the design criteria concerning rotor weight differentials for rotors made of different materials that have similar parameters and shafting. The balancing methodology for applications where rotor replaceability is a requirement is also covered. This report is intended for use as a reference when designing, fabricating, and troubleshooting turbomachinery shafting
Three-dimensional laser window formation
The NASA Lewis Research Center has developed and implemented a unique process for forming flawless three-dimensional laser windows. These windows represent a major part of specialized, nonintrusive laser data acquisition systems used in a variety of compressor and turbine research test facilities. This report discusses in detail the aspects of three-dimensional laser window formation. It focuses on the unique methodology and the peculiarities associated with the formation of these windows. Included in this discussion are the design criteria, bonding mediums, and evaluation testing for three-dimensional laser windows
A troubled relationship: corruption and reform of the public sector in development
Corruption is an issue of increasing visibility in the academic and policy literature on governance and public policy. Whilst it is often talked about, there appears to be some lack of clarity on both its nature and the nature of its determinants. This has led to some increase in the effort to combat it (in light of its significant costs for society) and it is questionable how effective these attempts have been to date. Corruption has a complex relationship with public sector reform. Reform is often executed which has as one of its objectives the control of corruption, but reform itself may be a cause of corruption according to some evidence from recent rounds of economic and public sector reform. The nature of the relationship is complicated by the fundamental nature of public sector reform. This is often âdualâ in nature, combining both destructive and constructive phases that redistribute the relative power of internal and external interest groups, create grievances, and present new opportunities for incumbents when compared to the pre-reform position. This paper presents an analysis of some of the data on corruption in relation to public sector reform, and attempts to clarify the nature of the corruption phenomenon in order to answer the question whether corruption can categorically be said to be a problem of public sector reform, or a consequence of it.Corruption; public administration; reform; transition; institutions
The signature of a splice
We study the behavior of the signature of colored links [Flo05, CF08] under
the splice operation. We extend the construction to colored links in integral
homology spheres and show that the signature is almost additive, with a
correction term independent of the links. We interpret this correction term as
the signature of a generalized Hopf link and give a simple closed formula to
compute it.Comment: Updated version. Sign corrected in Theorems 2.2 and 2.10 of the
previous version. Also Corollary 2.6 was corrected and an Example added. 24
pages, 5 figures. To appear in IMR
Slopes and signatures of links
We define the slope of a colored link in an integral homology sphere,
associated to admissible characters on the link group. Away from a certain
singular locus, the slope is a rational function which can be regarded as a
multivariate generalization of the Kojima--Yamasaki -function. It is the
ratio of two Conway potentials, provided that the latter makes sense;
otherwise, it is a new invariant. The slope is responsible for an extra
correction term in the signature formula for the splice of two links, in the
previously open exceptional case where both characters are admissible. Using a
similar construction for a special class of tangles, we formulate generalized
skein relations for the signature
redicting dynamic specifications of ADCs with a low-quality digital input signal
A new method is presented to test dynamic parameters of Analogue-to-Digital Converters (ADC). A noisy and nonlinear pulse is applied as the test stimulus, which is suitable for a multi-site test environment. The dynamic parameters are predicted using a machine-learning-based approach. A training step is required in order to build the mapping function using alternate signatures and the conventional test parameters, all measured on a set of converters. As a result, for industrial testing, only a simple signature-based test is performed on the Devices-Under-Test (DUTs). The signature measurements are provided to the mapping function that is used to predict the conventional dynamic parameters. The method is validated by simulation on a 12-bit 80 Ms/s pipelined ADC with a pulse wave input signal of 3 LSB noise and 7-bit nonlinear rising and falling edges. The final results show that the estimated mean error is less than 4% of the full range of the dynamic specifications
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