Convex Models of Vehicle Response to Unknown but Bounded Terrain

1991 ◽  
Vol 58 (2) ◽  
pp. 354-361 ◽  
Author(s):  
Yakov Ben-Haim ◽  
Isaac Elishakoff

This study presents a nonprobabilistic set theoretical approach to analyzing uncertainty in vehicle vibrations arising from motion along imperfectly known terrain. The uncertainty in the substrate is described by a set of allowed substrate profile functions. The analysis of the vehicle response consists in determining the range of variation of performance parameters, as the substrate profile varies over the set of allowed functions. This enables characterization of the uncertain but bounded motion of the vehicle as well as optimization of the vehicle design with respect to uncertainty in the substrate. Maximum acceleration during motion on an imperfectly known surface is determined and related to standard design guidelines for limiting exposure to vibrational acceleration. A method is developed for determining the greatest lower bound of the number of sign changes per second of the vibrational acceleration when moving over an irregular and incompletely specified substrate. Motion along uniformly bounded substrates is studied, as well as traversal of barriers.

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Prashanth Gopalan ◽  
Yunshan Wang ◽  
Berardi Sensale-Rodriguez

AbstractWhile terahertz spectroscopy can provide valuable information regarding the charge transport properties in semiconductors, its application for the characterization of low-conductive two-dimensional layers, i.e., σs <  < 1 mS, remains elusive. This is primarily due to the low sensitivity of direct transmission measurements to such small sheet conductivity levels. In this work, we discuss harnessing the extraordinary optical transmission through gratings consisting of metallic stripes to characterize such low-conductive two-dimensional layers. We analyze the geometric tradeoffs in these structures and provide physical insights, ultimately leading to general design guidelines for experiments enabling non-contact, non-destructive, highly sensitive characterization of such layers.


Weed Science ◽  
2004 ◽  
Vol 52 (4) ◽  
pp. 554-563 ◽  
Author(s):  
Giovanni Dinelli ◽  
Alessandra Bonetti ◽  
Ilaria Marotti ◽  
Maurizio Minelli ◽  
Pietro Catizone

Three ItalianLoliumweed populations, one susceptible and two resistant to diclofop, were characterized by the technique of inter simple sequence repeats (ISSR). The goal of this study was to taxonomically identify theseLoliumpopulations as well as to evaluate evidence for introgression of ISSR fragments fromFestucaand the potential role of this introgression in the diclofop response. ISSR analysis confirmed the genomic background of the weed populations to be consistent with that ofLolium. However, the great range of variation in ISSR banding patterns highlighted that the three ryegrass accessions are mixed populations made up of individuals resulting presumably from intrageneric and intergeneric hybridization in theLolium–Festucacomplex. TwoFestucagenus-discriminating and 20Festucaspecies-discriminating ISSR markers were screened among all the three ryegrass populations. The resistant Tuscania population carried the highest percentage ofFestucagenome (16.8%) followed by the resistant Roma (13.6%) and susceptible Vetralla (7.6%) populations. On the basis of these data some influence ofFestucagenome in diclofop resistance levels of studied ryegrass populations could be hypothesized.


1989 ◽  
Vol 12 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Ioana Cioranescu ◽  
Pedro Ubilla

2018 ◽  
Vol 7 (2) ◽  
pp. 89-98 ◽  
Author(s):  
Farzana Alam ◽  
Kazi Didarul Islam ◽  
SM Mahbubur Rahman

The research was conducted for the assessment of genetic diversity using both morphological and random amplified polymorphic DNA (RAPD) analysis of twelve guava (Psidium guajava L.) varieties growing in Bangladesh. Morphological characterization of guava varieties showed a wide range of variation. The highest variability was observed between Poly and Jelly varieties.Polymerase chain reaction with 5 arbitrary 10-mer and 3 arbitrary 12- mer RAPD primers produced a total of 50 bands of which 75.23 percent were polymorphic. The highest percentage of polymorphic loci (100%) was observed for primer A and the lowest (50%) for A03 primer. The UPGMA dendrogram revealed the segregation pattern and the difference of evolutionary changes. Guava varieties were separated into two main groups, one of them was made up of Chineese, Jelly, Kazi, Apple, L-49, Local-2 and Local-3. The other one was made up of Local-1, Poly, Kashi, Thai and Bombay. The highest genetic distance between Apple and Kazi peyara indicate that these varieties might be interesting in breeding programme for improving trait of interest. This scientific information could be used for further improvement of guava. Jahangirnagar University J. Biol. Sci. 7(2): 89-98, 2018 (December)


Author(s):  
Ali Roheim El-Ghalban ◽  
Qamar Iqbal ◽  
Shahab Khushnood ◽  
M. Arshad Qureshi ◽  
M. Shahid Khalil

Flow-induced vibration in heat exchangers has been a key source of concern in the process, power generation and nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported. Design of tube bundles with loosely supported tubes in baffles for process shell and tube heat exchanger and steam generator needs estimation of energy dissipation mechanisms or damping for a safer and long term operation. Damping has a major influence on the flow induced vibrations and is dependant on a variety of factors such as mechanical properties of the tube material, geometry and number of intermediate supports, the physical properties of shell-side fluid, type of tube motion, tube frequency, shell-side temperature etc. Various damping mechanisms have been identified and quantified such as Friction damping, Viscous damping, Squeeze film damping, Support damping and Two-Phase damping which affect the performance with respect to flow induced vibration design, including standard design guidelines. But generally the effects of the higher operating temperatures on the various damping mechanisms are neglected in the general design procedure. The operating temperatures play significant role on the contribution of various damping mechanisms. The current paper focuses on the thermal aspects of damping mechanisms subjected to single phase cross-flow in process heat exchangers and formulates the design guidelines for safer design based on experimental and empirical formulations. The research results show that he increase in the temperature results in the increase of the damping. Moreover it found that the natural frequency is higher for lower mass flow rate and lower working pressures and lower temperatures.


2021 ◽  
Author(s):  
Dylan Scott ◽  
Steven Graham ◽  
Bradford Songer ◽  
Brian Green ◽  
Michael Grotke ◽  
...  

This experimental effort is part of a larger program entitled Development of Ultra-High-Performance Concrete Tools and Design Guidelines. This program operates in accordance with an agreement concerning combating terrorism research and development between the United States of America Department of Defense and the Republic of Singapore Ministry of Defence. The objective of the program is to develop a better understanding of the potential benefits that may be achieved from the application of ultra-high-performance concrete (UHPC) materials for protective structures. The specific effort detailed in this report will provide insight into laboratory-scale mechanical properties of Cor-Tuf and a proprietary material termed UHPC-Singapore (UHPC-S).


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