The use of topology optimization in structural design under dynamic excitation is becoming more prevalent in the literature.While many such applications utilize frequency or time domain formulations,relatively few con...The use of topology optimization in structural design under dynamic excitation is becoming more prevalent in the literature.While many such applications utilize frequency or time domain formulations,relatively few consider stochastic dynamic excitations.This paper presents an efficient and compact code called TopSTO for structural topology optimization considering stationary stochastic dynamic loading using a method derived from random vibration theory.The theory,described in conjunction with the implementation in the provided code,is illustrated for a seismically excited building.This work demonstrates the efficiency of the approach in terms of both the computational resources and minimal amount of code required.This code is intended to serve as a baseline for understanding the theory and implementation of this topology optimization approach and as a foundation for additional applications and developments.展开更多
Anthropogenic pollutants have the potential to disrupt reproductive strategies. Little is known about how lead （Pb2＋） exposure disrupts individual-level responses in reproductive behaviors, which are important for ...Anthropogenic pollutants have the potential to disrupt reproductive strategies. Little is known about how lead （Pb2＋） exposure disrupts individual-level responses in reproductive behaviors, which are important for fitness. Drosophila melanogaster was used as a model system to deter- mine the effects of： 1） developmental lead exposure on pre-mating reproductive behaviors （i.e., mate preference）, and 2） lead exposure and mating preferences on fitness in the F0 parental generation and F1 un-exposed offspring. Wild-type strains of D. melanogaster were reared from egg stage to adulthood in control or leaded medium （250 μM PbAc） and tested for differences in： mate preference, male song performance, sex pheromone expression, fecundity, mortality, and body weight. F0 leaded females preferentially mated with leaded males （i.e., asymmetrical positive assortative mating） in 2-choice tests. This positive assortative mating was mediated by the females （and not the males） and was dependent upon context and developmental exposure to Pb. Neither the courtship song nor the sex pheromone profile expressed by control and leaded males medi- ated the positive assortative mating in leaded females. Leaded females did not incur a fitness cost in terms of reduced fecundity, increased mortality, or decreased body weight by mating with leaded males. These results suggest that sublethal exposure to lead during development can alter mate preferences in adults, but not fitness measures once lead exposure has been removed. We suggest that changes in mate preference may induce fitness costs, as well as long-term population and multi-generational implications, if pollution is persistent in the environment.展开更多
Now advertized in at least one locale as the ＇sexy ratio＇ with the caption, ＇Your hands give away your hotness＇ （http：//io9.com/ #!5794008; accessed 3 May 2011）, an online summary of a recent study linking faci...Now advertized in at least one locale as the ＇sexy ratio＇ with the caption, ＇Your hands give away your hotness＇ （http：//io9.com/ #!5794008; accessed 3 May 2011）, an online summary of a recent study linking facial attractiveness to the ratio of the index and ring fingers1 indicates that digit ratio （2D：4D） research has reached mainstream culture. Digit ratio, most commonly the ratio of the index to ring fingers in humans, is sexually dimorphic （males have lower values than females） with greater differences on their right hand.展开更多
Real-time hybrid simulation is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed i...Real-time hybrid simulation is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed in real time, thus allowing investigation of structural systems with rate-dependent components. Real-time hybrid simulation is challenging because it requires performance of all calculations, application of displacements, and acquisition of measured forces, within a very small increment of time. Furthermore, unless appropriate compensation for actuator dynamics is implemented, stability problems are likely to occur during the experiment. This paper presents an approach for real-time hybrid simulation in which compensation for actuator dynamics is implemented using a model-based feedforward compensator. The method is used to evaluate the response of a semi-active control of a structure employing an MR damper. Experimental results show good agreement with the predicted responses, demonstrating the effectiveness of the method for structural control performance assessment.展开更多
Publicly available building energy data are exploding--thirteen American cities and 14 states now require them by law. This emergence of data nudges building owners and tenants to reduce energy consumption by comparin...Publicly available building energy data are exploding--thirteen American cities and 14 states now require them by law. This emergence of data nudges building owners and tenants to reduce energy consumption by comparing their usage to that of similar buildings. However, vast untapped energy reductions and deeper physical understandings can still be extracted from these data. This paper extends the energy saving impact and provides key insight into building performance through publicly-disclosed data by describing three initiatives at a large design finn. An internal high performance design reporting program compares projects from around the world and across offices. A case study of 706 buildings in New York City illustrates the value of tracking large-scale patterns to a design firm. Per capita energy and carbon usage is correlated to life expectancy to better inform neighborhood and city design. As more data freely flow out into the public, engineers must strategically engage it.展开更多
In a recent publication appearing in the Asian Journal of Andrology, a team of researchers investigated the relationship of early hormone exposure to adult lung function. In the publication, ＇Second to fourth digit r...In a recent publication appearing in the Asian Journal of Andrology, a team of researchers investigated the relationship of early hormone exposure to adult lung function. In the publication, ＇Second to fourth digit ratio： a predictor of adult lung function＇, Park et al.,＇ described known sexual dimorphisms in lung function and a role for sex hormones in the development and regulation of lung function： the predominantly-male hormone, testosterone, enhances airway inflammation and the predominantly female hormone, estrogen, promotes lung development and protects against inflammation. Increasingly over the last decade and a half, digit ratio （the ratio of the lengths of the index to ring fingers） has served as a convenient biomarker for prenatal steroid exposure, and is thought to depend on exposure to testosterone relative to estrogen during development.展开更多
文摘The use of topology optimization in structural design under dynamic excitation is becoming more prevalent in the literature.While many such applications utilize frequency or time domain formulations,relatively few consider stochastic dynamic excitations.This paper presents an efficient and compact code called TopSTO for structural topology optimization considering stationary stochastic dynamic loading using a method derived from random vibration theory.The theory,described in conjunction with the implementation in the provided code,is illustrated for a seismically excited building.This work demonstrates the efficiency of the approach in terms of both the computational resources and minimal amount of code required.This code is intended to serve as a baseline for understanding the theory and implementation of this topology optimization approach and as a foundation for additional applications and developments.
文摘Anthropogenic pollutants have the potential to disrupt reproductive strategies. Little is known about how lead （Pb2＋） exposure disrupts individual-level responses in reproductive behaviors, which are important for fitness. Drosophila melanogaster was used as a model system to deter- mine the effects of： 1） developmental lead exposure on pre-mating reproductive behaviors （i.e., mate preference）, and 2） lead exposure and mating preferences on fitness in the F0 parental generation and F1 un-exposed offspring. Wild-type strains of D. melanogaster were reared from egg stage to adulthood in control or leaded medium （250 μM PbAc） and tested for differences in： mate preference, male song performance, sex pheromone expression, fecundity, mortality, and body weight. F0 leaded females preferentially mated with leaded males （i.e., asymmetrical positive assortative mating） in 2-choice tests. This positive assortative mating was mediated by the females （and not the males） and was dependent upon context and developmental exposure to Pb. Neither the courtship song nor the sex pheromone profile expressed by control and leaded males medi- ated the positive assortative mating in leaded females. Leaded females did not incur a fitness cost in terms of reduced fecundity, increased mortality, or decreased body weight by mating with leaded males. These results suggest that sublethal exposure to lead during development can alter mate preferences in adults, but not fitness measures once lead exposure has been removed. We suggest that changes in mate preference may induce fitness costs, as well as long-term population and multi-generational implications, if pollution is persistent in the environment.
文摘Now advertized in at least one locale as the ＇sexy ratio＇ with the caption, ＇Your hands give away your hotness＇ （http：//io9.com/ #!5794008; accessed 3 May 2011）, an online summary of a recent study linking facial attractiveness to the ratio of the index and ring fingers1 indicates that digit ratio （2D：4D） research has reached mainstream culture. Digit ratio, most commonly the ratio of the index to ring fingers in humans, is sexually dimorphic （males have lower values than females） with greater differences on their right hand.
基金National Science Foundation Graduate Research Fellowship
文摘Real-time hybrid simulation is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed in real time, thus allowing investigation of structural systems with rate-dependent components. Real-time hybrid simulation is challenging because it requires performance of all calculations, application of displacements, and acquisition of measured forces, within a very small increment of time. Furthermore, unless appropriate compensation for actuator dynamics is implemented, stability problems are likely to occur during the experiment. This paper presents an approach for real-time hybrid simulation in which compensation for actuator dynamics is implemented using a model-based feedforward compensator. The method is used to evaluate the response of a semi-active control of a structure employing an MR damper. Experimental results show good agreement with the predicted responses, demonstrating the effectiveness of the method for structural control performance assessment.
文摘Publicly available building energy data are exploding--thirteen American cities and 14 states now require them by law. This emergence of data nudges building owners and tenants to reduce energy consumption by comparing their usage to that of similar buildings. However, vast untapped energy reductions and deeper physical understandings can still be extracted from these data. This paper extends the energy saving impact and provides key insight into building performance through publicly-disclosed data by describing three initiatives at a large design finn. An internal high performance design reporting program compares projects from around the world and across offices. A case study of 706 buildings in New York City illustrates the value of tracking large-scale patterns to a design firm. Per capita energy and carbon usage is correlated to life expectancy to better inform neighborhood and city design. As more data freely flow out into the public, engineers must strategically engage it.
文摘In a recent publication appearing in the Asian Journal of Andrology, a team of researchers investigated the relationship of early hormone exposure to adult lung function. In the publication, ＇Second to fourth digit ratio： a predictor of adult lung function＇, Park et al.,＇ described known sexual dimorphisms in lung function and a role for sex hormones in the development and regulation of lung function： the predominantly-male hormone, testosterone, enhances airway inflammation and the predominantly female hormone, estrogen, promotes lung development and protects against inflammation. Increasingly over the last decade and a half, digit ratio （the ratio of the lengths of the index to ring fingers） has served as a convenient biomarker for prenatal steroid exposure, and is thought to depend on exposure to testosterone relative to estrogen during development.
